Configuring and managing networking

Red Hat Enterprise Linux 9

Managing network interfaces and advanced networking features

Red Hat Customer Content Services

Abstract

Using the networking capabilities of Red Hat Enterprise Linux (RHEL), you can configure your host to meet your organization's network and security requirements. For example:
  • You can configure bonds, VLANs, bridges, tunnels and other network types to connect the host to the network.
  • IPSec and WireGuard provide secure VPNs between hosts and networks.
  • RHEL also supports advanced networking features, such as policy-based routing and MultiPath TCP (MPTCP).

Making open source more inclusive

Red Hat is committed to replacing problematic language in our code, documentation, and web properties. We are beginning with these four terms: master, slave, blacklist, and whitelist. Because of the enormity of this endeavor, these changes will be implemented gradually over several upcoming releases. For more details, see our CTO Chris Wright’s message.

Providing feedback on Red Hat documentation

We appreciate your feedback on our documentation. Let us know how we can improve it.

Submitting feedback through Jira (account required)

  1. Log in to the Jira website.
  2. Click Create in the top navigation bar
  3. Enter a descriptive title in the Summary field.
  4. Enter your suggestion for improvement in the Description field. Include links to the relevant parts of the documentation.
  5. Click Create at the bottom of the dialogue.

Chapter 1. Implementing consistent network interface naming

The udev device manager implements consistent device naming in Red Hat Enterprise Linux. The device manager supports different naming schemes and, by default, assigns fixed names based on firmware, topology, and location information.

Without consistent device naming, the Linux kernel assigns names to network interfaces by combining a fixed prefix and an index. The index increases as the kernel initializes the network devices. For example, eth0 represents the first Ethernet device being probed on start-up. If you add another network interface controller to the system, the assignment of the kernel device names is no longer fixed because, after a reboot, the devices can initialize in a different order. In that case, the kernel can name the devices differently.

To solve this problem, udev assigns consistent device names. This has the following advantages:

  • Device names are stable across reboots.
  • Device names stay fixed even if you add or remove hardware.
  • Defective hardware can be seamlessly replaced.
  • The network naming is stateless and does not require explicit configuration files.
Warning

Generally, Red Hat does not support systems where consistent device naming is disabled. For exceptions, see the Is it safe to set net.ifnames=0 solution.

1.1. How the udev device manager renames network interfaces

To implement a consistent naming scheme for network interfaces, the udev device manager processes the following rule files in the listed order:

  1. Optional: /usr/lib/udev/rules.d/60-net.rules

    This file exists only if you install the initscripts-rename-device package. The /usr/lib/udev/rules.d/60-net.rules file defines that the deprecated /usr/lib/udev/rename_device helper utility searches for the HWADDR parameter in /etc/sysconfig/network-scripts/ifcfg-* files. If the value set in the variable matches the MAC address of an interface, the helper utility renames the interface to the name set in the DEVICE parameter of the ifcfg file.

    If the system uses only NetworkManager connection profiles in keyfile format, udev skips this step.

  2. Only on Dell systems: /usr/lib/udev/rules.d/71-biosdevname.rules

    This file exists only if the biosdevname package is installed, and the rules file defines that the biosdevname utility renames the interface according to its naming policy, if it was not renamed in the previous step.

    Note

    Install and use biosdevname only on Dell systems.

  3. /usr/lib/udev/rules.d/75-net-description.rules

    This file defines how udev examines the network interface and sets the properties in udev-internal variables. These variables are then processed in the next step by the /usr/lib/udev/rules.d/80-net-setup-link.rules file. Some of the properties can be undefined.

  4. /usr/lib/udev/rules.d/80-net-setup-link.rules

    This file calls the net_setup_link builtin of the udev service, and udev renames the interface based on the order of the policies in the NamePolicy parameter in the /usr/lib/systemd/network/99-default.link file. For further details, see Network interface naming policies.

    If none of the policies applies, udev does not rename the interface.

1.2. Network interface naming policies

By default, the udev device manager uses the /usr/lib/systemd/network/99-default.link file to determine which device naming policies to apply when it renames interfaces. The NamePolicy parameter in this file defines which policies udev uses and in which order:

NamePolicy=keep kernel database onboard slot path

The following table describes the different actions of udev based on which policy matches first as specified by the NamePolicy parameter:

PolicyDescriptionExample name

keep

If the device already has a name that was assigned in the user space, udev does not rename this device. For example, this is the case if the name was assigned during device creation or by a rename operation.

 

kernel

If the kernel indicates that a device name is predictable, udev does not rename this device.

lo

database

This policy assigns names based on mappings in the udev hardware database. For details, see the hwdb(7) man page.

idrac

onboard

Device names incorporate firmware or BIOS-provided index numbers for onboard devices.

eno1

slot

Device names incorporate firmware or BIOS-provided PCI Express (PCIe) hot-plug slot-index numbers.

ens1

path

Device names incorporate the physical location of the connector of the hardware.

enp1s0

mac

Device names incorporate the MAC address. By default, Red Hat Enterprise Linux does not use this policy, but administrators can enable it.

enx525400d5e0fb

Additional resources

1.3. Network interface naming schemes

The udev device manager uses certain stable interface attributes to generate consistent device names. For details about the naming schemes for different device types and platforms, see the systemd.net-naming-scheme(7) man page.

1.4. Customizing the prefix for Ethernet interfaces during installation

If you do not want to use the default device-naming policy for Ethernet interfaces, you can set a custom device prefix during the Red Hat Enterprise Linux (RHEL) installation.

Important

Red Hat supports systems with customized Ethernet prefixes only if you set the prefix during the RHEL installation. Using the prefixdevname utility on already deployed systems is not supported.

If you set a device prefix during the installation, the udev service uses the <prefix><index> format for Ethernet interfaces after the installation. For example, if you set the prefix net, the service assigns the names net0, net1, and so on to the Ethernet interfaces.

The udev service appends the index to the custom prefix, and preserves the index values of known Ethernet interfaces. If you add an interface, udev assigns an index value that is one greater than the previously-assigned index value to the new interface.

Prerequisites

  • The prefix consists of ASCII characters.
  • The prefix is an alphanumeric string.
  • The prefix is shorter than 16 characters.
  • The prefix does not conflict with any other well-known network interface prefix, such as eth, eno, ens, and em.

Procedure

  1. Boot the Red Hat Enterprise Linux installation media.
  2. In the boot manager, follow these steps:

    1. Select the Install Red Hat Enterprise Linux <version> entry.
    2. Press Tab to edit the entry.
    3. Append net.ifnames.prefix=<prefix> to the kernel options.
    4. Press Enter to start the installation program.
  3. Install Red Hat Enterprise Linux.

Verification

  • To verify the interface names, display the network interfaces:

    # ip link show
    ...
    2: net0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP mode DEFAULT group default qlen 1000
        link/ether 00:00:5e:00:53:1a brd ff:ff:ff:ff:ff:ff
    ...

1.5. Configuring user-defined network interface names by using udev rules

You can use udev rules to implement custom network interface names that reflect your organization’s requirements.

Procedure

  1. Identify the network interface that you want to rename:

    # ip link show
    ...
    enp1s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP mode DEFAULT group default qlen 1000
        link/ether 00:00:5e:00:53:1a brd ff:ff:ff:ff:ff:ff
    ...

    Record the MAC address of the interface.

  2. Display the device type ID of the interface:

    # cat /sys/class/net/enp1s0/type
    1
  3. Create the /etc/udev/rules.d/70-persistent-net.rules file, and add a rule for each interface that you want to rename:

    SUBSYSTEM=="net",ACTION=="add",ATTR{address}=="<MAC_address>",ATTR{type}=="<device_type_id>",NAME="<new_interface_name>"
    Important

    Use only 70-persistent-net.rules as a file name if you require consistent device names during the boot process. The dracut utility adds a file with this name to the initrd image if you regenerate the RAM disk image.

    For example, use the following rule to rename the interface with MAC address 00:00:5e:00:53:1a to provider0:

    SUBSYSTEM=="net",ACTION=="add",ATTR{address}=="00:00:5e:00:53:1a",ATTR{type}=="1",NAME="provider0"
  4. Optional: Regenerate the initrd RAM disk image:

    # dracut -f

    You require this step only if you need networking capabilities in the RAM disk. For example, this is the case if the root file system is stored on a network device, such as iSCSI.

  5. Identify which NetworkManager connection profile uses the interface that you want to rename:

    # nmcli -f device,name connection show
    DEVICE  NAME
    enp1s0  example_profile
    ...
  6. Unset the connection.interface-name property in the connection profile:

    # nmcli connection modify example_profile connection.interface-name ""
  7. Temporarily, configure the connection profile to match both the new and the previous interface name:

    # nmcli connection modify example_profile match.interface-name "provider0 enp1s0"
  8. Reboot the system:

    # reboot
  9. Verify that the device with the MAC address that you specified in the link file has been renamed to provider0:

    # ip link show
    provider0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq state UP mode DEFAULT group default qlen 1000
        link/ether 00:00:5e:00:53:1a brd ff:ff:ff:ff:ff:ff
    ...
  10. Configure the connection profile to match only the new interface name:

    # nmcli connection modify example_profile match.interface-name "provider0"

    You have now removed the old interface name from the connection profile.

  11. Reactivate the connection profile:

    # nmcli connection up example_profile

Additional resources

  • udev(7) man page

Chapter 2. Configuring an Ethernet connection

NetworkManager creates a connection profile for each Ethernet adapter that is installed in a host. By default, this profile uses DHCP for both IPv4 and IPv6 connections. Modify this automatically-created profile or add a new one in the following cases:

  • The network requires custom settings, such as a static IP address configuration.
  • You require multiple profiles because the host roams among different networks.

Red Hat Enterprise Linux provides administrators different options to configure Ethernet connections. For example:

  • Use nmcli to configure connections on the command line.
  • Use nmtui to configure connections in a text-based user interface.
  • Use the GNOME Settings menu or nm-connection-editor application to configure connections in a graphical interface.
  • Use nmstatectl to configure connections through the Nmstate API.
  • Use RHEL System Roles to automate the configuration of connections on one or multiple hosts.
Note

If you want to manually configure Ethernet connections on hosts running in the Microsoft Azure cloud, disable the cloud-init service or configure it to ignore the network settings retrieved from the cloud environment. Otherwise, cloud-init will override on the next reboot the network settings that you have manually configured.

2.1. Configuring an Ethernet connection by using nmcli

If you connect a host to the network over Ethernet, you can manage the connection’s settings on the command line by using the nmcli utility.

Prerequisites

  • A physical or virtual Ethernet Network Interface Controller (NIC) exists in the server’s configuration.

Procedure

  1. List the NetworkManager connection profiles:

    # nmcli connection show
    NAME                UUID                                  TYPE      DEVICE
    Wired connection 1  a5eb6490-cc20-3668-81f8-0314a27f3f75  ethernet  enp1s0

    By default, NetworkManager creates a profile for each NIC in the host. If you plan to connect this NIC only to a specific network, adapt the automatically-created profile. If you plan to connect this NIC to networks with different settings, create individual profiles for each network.

  2. If you want to create an additional connection profile, enter:

    # nmcli connection add con-name <connection-name> ifname <device-name> type ethernet

    Skip this step to modify an existing profile.

  3. Optional: Rename the connection profile:

    # nmcli connection modify "Wired connection 1" connection.id "Internal-LAN"

    On hosts with multiple profiles, a meaningful name makes it easier to identify the purpose of a profile.

  4. Display the current settings of the connection profile:

    # nmcli connection show Internal-LAN
    ...
    connection.interface-name:     enp1s0
    connection.autoconnect:        yes
    ipv4.method:                   auto
    ipv6.method:                   auto
    ...
  5. Configure the IPv4 settings:

    • To use DHCP, enter:

      # nmcli connection modify Internal-LAN ipv4.method auto

      Skip this step if ipv4.method is already set to auto (default).

    • To set a static IPv4 address, network mask, default gateway, DNS servers, and search domain, enter:

      # nmcli connection modify Internal-LAN ipv4.method manual ipv4.addresses 192.0.2.1/24 ipv4.gateway 192.0.2.254 ipv4.dns 192.0.2.200 ipv4.dns-search example.com
  6. Configure the IPv6 settings:

    • To use stateless address autoconfiguration (SLAAC), enter:

      # nmcli connection modify Internal-LAN ipv6.method auto

      Skip this step if ipv6.method is already set to auto (default).

    • To set a static IPv6 address, network mask, default gateway, DNS servers, and search domain, enter:

      # nmcli connection modify Internal-LAN ipv6.method manual ipv6.addresses 2001:db8:1::fffe/64 ipv6.gateway 2001:db8:1::fffe ipv6.dns 2001:db8:1::ffbb ipv6.dns-search example.com
  7. To customize other settings in the profile, use the following command:

    # nmcli connection modify <connection-name> <setting> <value>

    Enclose values with spaces or semicolons in quotes.

  8. Activate the profile:

    # nmcli connection up Internal-LAN

Verification

  1. Display the IP settings of the NIC:

    # ip address show enp1s0
    2: enp1s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP group default qlen 1000
        link/ether 52:54:00:17:b8:b6 brd ff:ff:ff:ff:ff:ff
        inet 192.0.2.1/24 brd 192.0.2.255 scope global noprefixroute enp1s0
           valid_lft forever preferred_lft forever
        inet6 2001:db8:1::fffe/64 scope global noprefixroute
           valid_lft forever preferred_lft forever
  2. Display the IPv4 default gateway:

    # ip route show default
    default via 192.0.2.254 dev enp1s0 proto static metric 102
  3. Display the IPv6 default gateway:

    # ip -6 route show default
    default via 2001:db8:1::ffee dev enp1s0 proto static metric 102 pref medium
  4. Display the DNS settings:

    # cat /etc/resolv.conf
    search example.com
    nameserver 192.0.2.200
    nameserver 2001:db8:1::ffbb

    If multiple connection profiles are active at the same time, the order of nameserver entries depend on the DNS priority values in these profile and the connection types.

  5. Use the ping utility to verify that this host can send packets to other hosts:

    # ping <host-name-or-IP-address>

Troubleshooting

  • Verify that the network cable is plugged-in to the host and a switch.
  • Check whether the link failure exists only on this host or also on other hosts connected to the same switch.
  • Verify that the network cable and the network interface are working as expected. Perform hardware diagnosis steps and replace defect cables and network interface cards.
  • If the configuration on the disk does not match the configuration on the device, starting or restarting NetworkManager creates an in-memory connection that reflects the configuration of the device. For further details and how to avoid this problem, see the NetworkManager duplicates a connection after restart of NetworkManager service solution.

2.2. Configuring an Ethernet connection by using the nmcli interactive editor

If you connect a host to the network over Ethernet, you can manage the connection’s settings on the command line by using the nmcli utility.

Prerequisites

  • A physical or virtual Ethernet Network Interface Controller (NIC) exists in the server’s configuration.

Procedure

  1. List the NetworkManager connection profiles:

    # nmcli connection show
    NAME                UUID                                  TYPE      DEVICE
    Wired connection 1  a5eb6490-cc20-3668-81f8-0314a27f3f75  ethernet  enp1s0

    By default, NetworkManager creates a profile for each NIC in the host. If you plan to connect this NIC only to a specific network, adapt the automatically-created profile. If you plan to connect this NIC to networks with different settings, create individual profiles for each network.

  2. Start nmcli in interactive mode:

    • To create an additional connection profile, enter:

      # nmcli connection edit type ethernet con-name "<connection-name>"
    • To modify an existing connection profile, enter:

      # nmcli connection edit con-name "<connection-name>"
  3. Optional: Rename the connection profile:

    nmcli> set connection.id Internal-LAN

    On hosts with multiple profiles, a meaningful name makes it easier to identify the purpose of a profile.

    Do not use quotes to set an ID that contains spaces to avoid that nmcli makes the quotes part of the name. For example, to set Example Connection as ID, enter set connection.id Example Connection.

  4. Display the current settings of the connection profile:

    nmcli> print
    ...
    connection.interface-name:     enp1s0
    connection.autoconnect:        yes
    ipv4.method:                   auto
    ipv6.method:                   auto
    ...
  5. If you create a new connection profile, set the network interface:

    nmcli> set connection.interface-name enp1s0
  6. Configure the IPv4 settings:

    • To use DHCP, enter:

      nmcli> set ipv4.method auto

      Skip this step if ipv4.method is already set to auto (default).

    • To set a static IPv4 address, network mask, default gateway, DNS servers, and search domain, enter:

      nmcli> ipv4.addresses 192.0.2.1/24
      Do you also want to set 'ipv4.method' to 'manual'? [yes]: yes
      nmcli> ipv4.gateway 192.0.2.254
      nmcli> ipv4.dns 192.0.2.200
      nmcli> ipv4.dns-search example.com
  7. Configure the IPv6 settings:

    • To use stateless address autoconfiguration (SLAAC), enter:

      nmcli> set ipv6.method auto

      Skip this step if ipv6.method is already set to auto (default).

    • To set a static IPv6 address, network mask, default gateway, DNS servers, and search domain, enter:

      nmcli> ipv6.addresses 2001:db8:1::fffe/64
      Do you also want to set 'ipv6.method' to 'manual'? [yes]: yes
      nmcli> ipv6.gateway 2001:db8:1::fffe
      nmcli> ipv6.dns 2001:db8:1::ffbb
      nmcli> ipv6.dns-search example.com
  8. Save and activate the connection:

    nmcli> save persistent
  9. Leave the interactive mode:

    nmcli> quit

Verification

  1. Display the IP settings of the NIC:

    # ip address show enp1s0
    2: enp1s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP group default qlen 1000
        link/ether 52:54:00:17:b8:b6 brd ff:ff:ff:ff:ff:ff
        inet 192.0.2.1/24 brd 192.0.2.255 scope global noprefixroute enp1s0
           valid_lft forever preferred_lft forever
        inet6 2001:db8:1::fffe/64 scope global noprefixroute
           valid_lft forever preferred_lft forever
  2. Display the IPv4 default gateway:

    # ip route show default
    default via 192.0.2.254 dev enp1s0 proto static metric 102
  3. Display the IPv6 default gateway:

    # ip -6 route show default
    default via 2001:db8:1::ffee dev enp1s0 proto static metric 102 pref medium
  4. Display the DNS settings:

    # cat /etc/resolv.conf
    search example.com
    nameserver 192.0.2.200
    nameserver 2001:db8:1::ffbb

    If multiple connection profiles are active at the same time, the order of nameserver entries depend on the DNS priority values in these profile and the connection types.

  5. Use the ping utility to verify that this host can send packets to other hosts:

    # ping <host-name-or-IP-address>

Troubleshooting

  • Verify that the network cable is plugged-in to the host and a switch.
  • Check whether the link failure exists only on this host or also on other hosts connected to the same switch.
  • Verify that the network cable and the network interface are working as expected. Perform hardware diagnosis steps and replace defect cables and network interface cards.
  • If the configuration on the disk does not match the configuration on the device, starting or restarting NetworkManager creates an in-memory connection that reflects the configuration of the device. For further details and how to avoid this problem, see the NetworkManager duplicates a connection after restart of NetworkManager service solution

2.3. Configuring an Ethernet connection by using nmtui

If you connect a host to the network over Ethernet, you can manage the connection’s settings in a text-based user interface by using the nmtui application. Use nmtui to create new profiles and to update existing ones on a host without a graphical interface.

Note

In nmtui:

  • Navigate by using the cursor keys.
  • Press a button by selecting it and hitting Enter.
  • Select and deselect checkboxes by using Space.

Prerequisites

  • A physical or virtual Ethernet Network Interface Controller (NIC) exists in the server’s configuration.

Procedure

  1. If you do not know the network device name you want to use in the connection, display the available devices:

    # nmcli device status
    DEVICE     TYPE      STATE                   CONNECTION
    enp1s0     ethernet  unavailable             --
    ...
  2. Start nmtui:

    # nmtui
  3. Select Edit a connection, and press Enter.
  4. Choose whether to add a new connection profile or to modify an existing one:

    • To create a new profile:

      1. Press the Add button.
      2. Select Ethernet from the list of network types, and press Enter.
    • To modify an existing profile, select the profile from the list, and press Enter.
  5. Optional: Update the name of the connection profile.

    On hosts with multiple profiles, a meaningful name makes it easier to identify the purpose of a profile.

  6. If you create a new connection profile, enter the network device name into the Device field.
  7. Depending on your environment, configure the IP address settings in the IPv4 configuration and IPv6 configuration areas accordingly. For this, press the button next to these areas, and select:

    • Disabled, if this connection does not require an IP address.
    • Automatic, if a DHCP server dynamically assigns an IP address to this NIC.
    • Manual, if the network requires static IP address settings. In this case, you must fill further fields:

      1. Press the Show button next to the protocol you want to configure to display additional fields.
      2. Press the Add button next to Addresses, and enter the IP address and the subnet mask in Classless Inter-Domain Routing (CIDR) format.

        If you do not specify a subnet mask, NetworkManager sets a /32 subnet mask for IPv4 addresses and /64 for IPv6 addresses.

      3. Enter the address of the default gateway.
      4. Press the Add button next to DNS servers, and enter the DNS server address.
      5. Press the Add button next to Search domains, and enter the DNS search domain.

    Figure 2.1. Example of an Ethernet connection with static IP address settings

    nmtui ethernet static IP
  8. Press the OK button to create and automatically activate the new connection.
  9. Press the Back button to return to the main menu.
  10. Select Quit, and press Enter to close the nmtui application.

Verification

  1. Display the IP settings of the NIC:

    # ip address show enp1s0
    2: enp1s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP group default qlen 1000
        link/ether 52:54:00:17:b8:b6 brd ff:ff:ff:ff:ff:ff
        inet 192.0.2.1/24 brd 192.0.2.255 scope global noprefixroute enp1s0
           valid_lft forever preferred_lft forever
        inet6 2001:db8:1::fffe/64 scope global noprefixroute
           valid_lft forever preferred_lft forever
  2. Display the IPv4 default gateway:

    # ip route show default
    default via 192.0.2.254 dev enp1s0 proto static metric 102
  3. Display the IPv6 default gateway:

    # ip -6 route show default
    default via 2001:db8:1::ffee dev enp1s0 proto static metric 102 pref medium
  4. Display the DNS settings:

    # cat /etc/resolv.conf
    search example.com
    nameserver 192.0.2.200
    nameserver 2001:db8:1::ffbb

    If multiple connection profiles are active at the same time, the order of nameserver entries depend on the DNS priority values in these profile and the connection types.

  5. Use the ping utility to verify that this host can send packets to other hosts:

    # ping <host-name-or-IP-address>

Troubleshooting

  • Verify that the network cable is plugged-in to the host and a switch.
  • Check whether the link failure exists only on this host or also on other hosts connected to the same switch.
  • Verify that the network cable and the network interface are working as expected. Perform hardware diagnosis steps and replace defect cables and network interface cards.
  • If the configuration on the disk does not match the configuration on the device, starting or restarting NetworkManager creates an in-memory connection that reflects the configuration of the device. For further details and how to avoid this problem, see the NetworkManager duplicates a connection after restart of NetworkManager service solution.

2.4. Configuring an Ethernet connection by using control-center

If you connect a host to the network over Ethernet, you can manage the connection’s settings with a graphical interface by using the GNOME Settings menu.

Note that control-center does not support as many configuration options as the nm-connection-editor application or the nmcli utility.

Prerequisites

  • A physical or virtual Ethernet Network Interface Controller (NIC) exists in the server’s configuration.
  • GNOME is installed.

Procedure

  1. Press the Super key, enter Settings, and press Enter.
  2. Select Network in the navigation on the left.
  3. Choose whether to add a new connection profile or to modify an existing one:

    • To create a new profile, click the + button next to the Ethernet entry.
    • To modify an existing profile, click the gear icon next to the profile entry.
  4. Optional: On the Identity tab, update the name of the connection profile.

    On hosts with multiple profiles, a meaningful name makes it easier to identify the purpose of a profile.

  5. Depending on your environment, configure the IP address settings on the IPv4 and IPv6 tabs accordingly:

    • To use DHCP or IPv6 stateless address autoconfiguration (SLAAC), select Automatic (DHCP) as method (default).
    • To set a static IP address, network mask, default gateway, DNS servers, and search domain, select Manual as method, and fill the fields on the tabs:

      IP settings gnome settings
  6. Depending on whether you add or modify a connection profile, click the Add or Apply button to save the connection.

    The GNOME control-center automatically activates the connection.

Verification

  1. Display the IP settings of the NIC:

    # ip address show enp1s0
    2: enp1s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP group default qlen 1000
        link/ether 52:54:00:17:b8:b6 brd ff:ff:ff:ff:ff:ff
        inet 192.0.2.1/24 brd 192.0.2.255 scope global noprefixroute enp1s0
           valid_lft forever preferred_lft forever
        inet6 2001:db8:1::fffe/64 scope global noprefixroute
           valid_lft forever preferred_lft forever
  2. Display the IPv4 default gateway:

    # ip route show default
    default via 192.0.2.254 dev enp1s0 proto static metric 102
  3. Display the IPv6 default gateway:

    # ip -6 route show default
    default via 2001:db8:1::ffee dev enp1s0 proto static metric 102 pref medium
  4. Display the DNS settings:

    # cat /etc/resolv.conf
    search example.com
    nameserver 192.0.2.200
    nameserver 2001:db8:1::ffbb

    If multiple connection profiles are active at the same time, the order of nameserver entries depend on the DNS priority values in these profile and the connection types.

  5. Use the ping utility to verify that this host can send packets to other hosts:

    # ping <host-name-or-IP-address>

Troubleshooting steps

  • Verify that the network cable is plugged-in to the host and a switch.
  • Check whether the link failure exists only on this host or also on other hosts connected to the same switch.
  • Verify that the network cable and the network interface are working as expected. Perform hardware diagnosis steps and replace defect cables and network interface cards.
  • If the configuration on the disk does not match the configuration on the device, starting or restarting NetworkManager creates an in-memory connection that reflects the configuration of the device. For further details and how to avoid this problem, see the NetworkManager duplicates a connection after restart of NetworkManager service solution.

2.5. Configuring an Ethernet connection by using nm-connection-editor

If you connect a host to the network over Ethernet, you can manage the connection’s settings with a graphical interface by using the nm-connection-editor application.

Prerequisites

  • A physical or virtual Ethernet Network Interface Controller (NIC) exists in the server’s configuration.
  • GNOME is installed.

Procedure

  1. Open a terminal, and enter:

    $ nm-connection-editor
  2. Choose whether to add a new connection profile or to modify an existing one:

    • To create a new profile:

      1. Click the + button
      2. Select Ethernet as connection type, and click Create.
    • To modify an existing profile, double-click the profile entry.
  3. Optional: Update the name of the profile in the Connection Name field.

    On hosts with multiple profiles, a meaningful name makes it easier to identify the purpose of a profile.

  4. If you create a new profile, select the device on the Ethernet tab:

    ethernet connection settings

  5. Depending on your environment, configure the IP address settings on the IPv4 Settings and IPv6 Settings tabs accordingly:

    • To use DHCP or IPv6 stateless address autoconfiguration (SLAAC), select Automatic (DHCP) as method (default).
    • To set a static IP address, network mask, default gateway, DNS servers, and search domain, select Manual as method, and fill the fields on the tabs:

      IP settings nm connection editor
  6. Click Save.
  7. Close nm-connection-editor.

Verification

  1. Display the IP settings of the NIC:

    # ip address show enp1s0
    2: enp1s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP group default qlen 1000
        link/ether 52:54:00:17:b8:b6 brd ff:ff:ff:ff:ff:ff
        inet 192.0.2.1/24 brd 192.0.2.255 scope global noprefixroute enp1s0
           valid_lft forever preferred_lft forever
        inet6 2001:db8:1::fffe/64 scope global noprefixroute
           valid_lft forever preferred_lft forever
  2. Display the IPv4 default gateway:

    # ip route show default
    default via 192.0.2.254 dev enp1s0 proto static metric 102
  3. Display the IPv6 default gateway:

    # ip -6 route show default
    default via 2001:db8:1::ffee dev enp1s0 proto static metric 102 pref medium
  4. Display the DNS settings:

    # cat /etc/resolv.conf
    search example.com
    nameserver 192.0.2.200
    nameserver 2001:db8:1::ffbb

    If multiple connection profiles are active at the same time, the order of nameserver entries depend on the DNS priority values in these profile and the connection types.

  5. Use the ping utility to verify that this host can send packets to other hosts:

    # ping <host-name-or-IP-address>

Troubleshooting steps

  • Verify that the network cable is plugged-in to the host and a switch.
  • Check whether the link failure exists only on this host or also on other hosts connected to the same switch.
  • Verify that the network cable and the network interface are working as expected. Perform hardware diagnosis steps and replace defect cables and network interface cards.
  • If the configuration on the disk does not match the configuration on the device, starting or restarting NetworkManager creates an in-memory connection that reflects the configuration of the device. For further details and how to avoid this problem, see the NetworkManager duplicates a connection after restart of NetworkManager service solution.

2.6. Configuring an Ethernet connection with a static IP address by using nmstatectl

Use the nmstatectl utility to configure an Ethernet connection through the Nmstate API. The Nmstate API ensures that, after setting the configuration, the result matches the configuration file. If anything fails, nmstatectl automatically rolls back the changes to avoid leaving the system in an incorrect state.

Prerequisites

  • A physical or virtual Ethernet Network Interface Controller (NIC) exists in the server’s configuration.
  • The nmstate package is installed.

Procedure

  1. Create a YAML file, for example ~/create-ethernet-profile.yml, with the following content:

    ---
    interfaces:
    - name: enp1s0
      type: ethernet
      state: up
      ipv4:
        enabled: true
        address:
        - ip: 192.0.2.1
          prefix-length: 24
        dhcp: false
      ipv6:
        enabled: true
        address:
        - ip: 2001:db8:1::1
          prefix-length: 64
        autoconf: false
        dhcp: false
    routes:
      config:
      - destination: 0.0.0.0/0
        next-hop-address: 192.0.2.254
        next-hop-interface: enp1s0
      - destination: ::/0
        next-hop-address: 2001:db8:1::fffe
        next-hop-interface: enp1s0
    dns-resolver:
      config:
        search:
        - example.com
        server:
        - 192.0.2.200
        - 2001:db8:1::ffbb

    These settings define an Ethernet connection profile for the enp1s0 device with the following settings:

    • A static IPv4 address - 192.0.2.1 with the /24 subnet mask
    • A static IPv6 address - 2001:db8:1::1 with the /64 subnet mask
    • An IPv4 default gateway - 192.0.2.254
    • An IPv6 default gateway - 2001:db8:1::fffe
    • An IPv4 DNS server - 192.0.2.200
    • An IPv6 DNS server - 2001:db8:1::ffbb
    • A DNS search domain - example.com
    Note

    You can define identifier: mac-address and mac-address: <ACTUAL-NIC-MACADDRESS> properties directly to the interfaces property to identify the network interface card by its MAC address instead of its name (such as enp1s0).

    For example:

    ---
    interfaces:
    - name: <profile-name>
      type: ethernet
      identifier: mac-address
      mac-address: <ACTUAL-NIC-MACADDRESS>
      state: up
      ipv4:
        enabled: true
        auto-dns: true
        auto-gateway: true
        auto-routes: true
        dhcp: true
        ...

    For more details, see the nmstate supports MAC address identifiable network interface release note.

  2. Apply the settings to the system:

    # nmstatectl apply ~/create-ethernet-profile.yml

Verification

  1. Display the current state in YAML format:

    # nmstatectl show enp1s0
  2. Display the IP settings of the NIC:

    # ip address show enp1s0
    2: enp1s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP group default qlen 1000
        link/ether 52:54:00:17:b8:b6 brd ff:ff:ff:ff:ff:ff
        inet 192.0.2.1/24 brd 192.0.2.255 scope global noprefixroute enp1s0
           valid_lft forever preferred_lft forever
        inet6 2001:db8:1::fffe/64 scope global noprefixroute
           valid_lft forever preferred_lft forever
  3. Display the IPv4 default gateway:

    # ip route show default
    default via 192.0.2.254 dev enp1s0 proto static metric 102
  4. Display the IPv6 default gateway:

    # ip -6 route show default
    default via 2001:db8:1::ffee dev enp1s0 proto static metric 102 pref medium
  5. Display the DNS settings:

    # cat /etc/resolv.conf
    search example.com
    nameserver 192.0.2.200
    nameserver 2001:db8:1::ffbb

    If multiple connection profiles are active at the same time, the order of nameserver entries depend on the DNS priority values in these profile and the connection types.

  6. Use the ping utility to verify that this host can send packets to other hosts:

    # ping <host-name-or-IP-address>

Additional resources

  • nmstatectl(8) man page
  • /usr/share/doc/nmstate/examples/ directory

2.7. Configuring an Ethernet connection with a static IP address by using the network RHEL System Role with an interface name

You can remotely configure an Ethernet connection by using the network RHEL System Role.

Perform this procedure on the Ansible control node.

Prerequisites

  • You have prepared the control node and the managed nodes
  • You are logged in to the control node as a user who can run playbooks on the managed nodes.
  • The account you use to connect to the managed nodes has sudo permissions on them.
  • The managed nodes or groups of managed nodes on which you want to run this playbook are listed in the Ansible inventory file.
  • A physical or virtual Ethernet device exists in the server’s configuration.
  • The managed nodes use NetworkManager to configure the network.

Procedure

  1. Create a playbook file, for example ~/ethernet-static-IP.yml, with the following content:

    ---
    - name: Configure the network
      hosts: managed-node-01.example.com
      tasks:
      - name: Configure an Ethernet connection with static IP
        include_role:
          name: rhel-system-roles.network
    
        vars:
          network_connections:
            - name: enp1s0
              interface_name: enp1s0
              type: ethernet
              autoconnect: yes
              ip:
                address:
                  - 192.0.2.1/24
                  - 2001:db8:1::1/64
                gateway4: 192.0.2.254
                gateway6: 2001:db8:1::fffe
                dns:
                  - 192.0.2.200
                  - 2001:db8:1::ffbb
                dns_search:
                  - example.com
              state: up

    These settings define an Ethernet connection profile for the enp1s0 device with the following settings:

    • A static IPv4 address - 192.0.2.1 with a /24 subnet mask
    • A static IPv6 address - 2001:db8:1::1 with a /64 subnet mask
    • An IPv4 default gateway - 192.0.2.254
    • An IPv6 default gateway - 2001:db8:1::fffe
    • An IPv4 DNS server - 192.0.2.200
    • An IPv6 DNS server - 2001:db8:1::ffbb
    • A DNS search domain - example.com
  2. Validate the playbook syntax:

    # ansible-playbook ~/ethernet-static-IP.yml --syntax-check

    Note that this command only validates the syntax and does not protect against a wrong but valid configuration.

  3. Run the playbook:

    # ansible-playbook ~/ethernet-static-IP.yml

Additional resources

  • /usr/share/ansible/roles/rhel-system-roles.network/README.md file

2.8. Configuring an Ethernet connection with a static IP address by using the network RHEL System Role with a device path

You can remotely configure an Ethernet connection using the network RHEL System Role.

You can identify the device path with the following command:

# udevadm info /sys/class/net/<device_name> | grep ID_PATH=

Perform this procedure on the Ansible control node.

Prerequisites

  • You have prepared the control node and the managed nodes
  • You are logged in to the control node as a user who can run playbooks on the managed nodes.
  • The account you use to connect to the managed nodes has sudo permissions on them.
  • The managed nodes or groups of managed nodes on which you want to run this playbook are listed in the Ansible inventory file.
  • A physical or virtual Ethernet device exists in the server’s configuration.
  • The managed nodes use NetworkManager to configure the network.

Procedure

  1. Create a playbook file, for example ~/ethernet-static-IP.yml, with the following content:

    ---
    - name: Configure the network
      hosts: managed-node-01.example.com
      tasks:
      - name: Configure an Ethernet connection with static IP
        include_role:
          name: rhel-system-roles.network
    
        vars:
          network_connections:
            - name: example
              match:
                path:
                  - pci-0000:00:0[1-3].0
                  - &!pci-0000:00:02.0
              type: ethernet
              autoconnect: yes
              ip:
                address:
                  - 192.0.2.1/24
                  - 2001:db8:1::1/64
                gateway4: 192.0.2.254
                gateway6: 2001:db8:1::fffe
                dns:
                  - 192.0.2.200
                  - 2001:db8:1::ffbb
                dns_search:
                  - example.com
              state: up

    These settings define an Ethernet connection profile with the following settings:

    • A static IPv4 address - 192.0.2.1 with a /24 subnet mask
    • A static IPv6 address - 2001:db8:1::1 with a /64 subnet mask
    • An IPv4 default gateway - 192.0.2.254
    • An IPv6 default gateway - 2001:db8:1::fffe
    • An IPv4 DNS server - 192.0.2.200
    • An IPv6 DNS server - 2001:db8:1::ffbb
    • A DNS search domain - example.com

    The match parameter in this example defines that Ansible applies the play to devices that match PCI ID 0000:00:0[1-3].0, but not 0000:00:02.0. For further details about special modifiers and wild cards you can use, see the match parameter description in the /usr/share/ansible/roles/rhel-system-roles.network/README.md file.

  2. Validate the playbook syntax:

    # ansible-playbook ~/ethernet-static-IP.yml --syntax-check

    Note that this command only validates the syntax and does not protect against a wrong but valid configuration.

  3. Run the playbook:

    # ansible-playbook ~/ethernet-static-IP.yml

Additional resources

  • /usr/share/ansible/roles/rhel-system-roles.network/README.md file

2.9. Configuring an Ethernet connection with a dynamic IP address by using nmstatectl

Use the nmstatectl utility to configure an Ethernet connection through the Nmstate API. The Nmstate API ensures that, after setting the configuration, the result matches the configuration file. If anything fails, nmstatectl automatically rolls back the changes to avoid leaving the system in an incorrect state.

Prerequisites

  • A physical or virtual Ethernet Network Interface Controller (NIC) exists in the server’s configuration.
  • A DHCP server is available in the network.
  • The nmstate package is installed.

Procedure

  1. Create a YAML file, for example ~/create-ethernet-profile.yml, with the following content:

    ---
    interfaces:
    - name: enp1s0
      type: ethernet
      state: up
      ipv4:
        enabled: true
        auto-dns: true
        auto-gateway: true
        auto-routes: true
        dhcp: true
      ipv6:
        enabled: true
        auto-dns: true
        auto-gateway: true
        auto-routes: true
        autoconf: true
        dhcp: true

    These settings define an Ethernet connection profile for the enp1s0 device. The connection retrieves IPv4 addresses, IPv6 addresses, default gateway, routes, DNS servers, and search domains from a DHCP server and IPv6 stateless address autoconfiguration (SLAAC).

    Note

    You can define identifier: mac-address and mac-address: <ACTUAL-NIC-MACADDRESS> properties directly to the interfaces property to identify the network interface card by its MAC address instead of its name (such as enp1s0).

    For example:

    ---
    interfaces:
    - name: <profile-name>
      type: ethernet
      identifier: mac-address
      mac-address: <ACTUAL-NIC-MACADDRESS>
      state: up
      ipv4:
        enabled: true
        auto-dns: true
        auto-gateway: true
        auto-routes: true
        dhcp: true
        ...
  2. Apply the settings to the system:

    # nmstatectl apply ~/create-ethernet-profile.yml

Verification

  1. Display the current state in YAML format:

    # nmstatectl show enp1s0
  2. Display the IP settings of the NIC:

    # ip address show enp1s0
    2: enp1s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP group default qlen 1000
        link/ether 52:54:00:17:b8:b6 brd ff:ff:ff:ff:ff:ff
        inet 192.0.2.1/24 brd 192.0.2.255 scope global noprefixroute enp1s0
           valid_lft forever preferred_lft forever
        inet6 2001:db8:1::fffe/64 scope global noprefixroute
           valid_lft forever preferred_lft forever
  3. Display the IPv4 default gateway:

    # ip route show default
    default via 192.0.2.254 dev enp1s0 proto static metric 102
  4. Display the IPv6 default gateway:

    # ip -6 route show default
    default via 2001:db8:1::ffee dev enp1s0 proto static metric 102 pref medium
  5. Display the DNS settings:

    # cat /etc/resolv.conf
    search example.com
    nameserver 192.0.2.200
    nameserver 2001:db8:1::ffbb

    If multiple connection profiles are active at the same time, the order of nameserver entries depend on the DNS priority values in these profile and the connection types.

  6. Use the ping utility to verify that this host can send packets to other hosts:

    # ping <host-name-or-IP-address>

Additional resources

  • nmstatectl(8) man page
  • /usr/share/doc/nmstate/examples/ directory

2.10. Configuring an Ethernet connection with a dynamic IP address by using the network RHEL System Role with an interface name

You can remotely configure an Ethernet connection using the network RHEL System Role. For connections with dynamic IP address settings, NetworkManager requests the IP settings for the connection from a DHCP server.

Perform this procedure on the Ansible control node.

Prerequisites

  • You have prepared the control node and the managed nodes
  • You are logged in to the control node as a user who can run playbooks on the managed nodes.
  • The account you use to connect to the managed nodes has sudo permissions on them.
  • The managed nodes or groups of managed nodes on which you want to run this playbook are listed in the Ansible inventory file.
  • A physical or virtual Ethernet device exists in the server’s configuration.
  • A DHCP server is available in the network
  • The managed nodes use NetworkManager to configure the network.

Procedure

  1. Create a playbook file, for example ~/ethernet-dynamic-IP.yml, with the following content:

    ---
    - name: Configure the network
      hosts: managed-node-01.example.com
      tasks:
      - name: Configure an Ethernet connection with dynamic IP
        include_role:
          name: rhel-system-roles.network
    
        vars:
          network_connections:
            - name: enp1s0
              interface_name: enp1s0
              type: ethernet
              autoconnect: yes
              ip:
                dhcp4: yes
                auto6: yes
              state: up

    These settings define an Ethernet connection profile for the enp1s0 device. The connection retrieves IPv4 addresses, IPv6 addresses, default gateway, routes, DNS servers, and search domains from a DHCP server and IPv6 stateless address autoconfiguration (SLAAC).

  2. Validate the playbook syntax:

    # ansible-playbook ~/ethernet-dynamic-IP.yml --syntax-check

    Note that this command only validates the syntax and does not protect against a wrong but valid configuration.

  3. Run the playbook:

    # ansible-playbook ~/ethernet-dynamic-IP.yml

Additional resources

  • /usr/share/ansible/roles/rhel-system-roles.network/README.md file

2.11. Configuring an Ethernet connection with a dynamic IP address by using the network RHEL System Role with a device path

You can remotely configure an Ethernet connection using the network RHEL System Role. For connections with dynamic IP address settings, NetworkManager requests the IP settings for the connection from a DHCP server.

You can identify the device path with the following command:

# udevadm info /sys/class/net/<device_name> | grep ID_PATH=

Perform this procedure on the Ansible control node.

Prerequisites

  • You have prepared the control node and the managed nodes
  • You are logged in to the control node as a user who can run playbooks on the managed nodes.
  • The account you use to connect to the managed nodes has sudo permissions on them.
  • The managed nodes or groups of managed nodes on which you want to run this playbook are listed in the Ansible inventory file.
  • A physical or virtual Ethernet device exists in the server’s configuration.
  • A DHCP server is available in the network.
  • The managed hosts use NetworkManager to configure the network.

Procedure

  1. Create a playbook file, for example ~/ethernet-dynamic-IP.yml, with the following content:

    ---
    - name: Configure the network
      hosts: managed-node-01.example.com
      tasks:
      - name: Configure an Ethernet connection with dynamic IP
        include_role:
          name: rhel-system-roles.network
    
        vars:
          network_connections:
            - name: example
              match:
                path:
                  - pci-0000:00:0[1-3].0
                  - &!pci-0000:00:02.0
              type: ethernet
              autoconnect: yes
              ip:
                dhcp4: yes
                auto6: yes
              state: up

    These settings define an Ethernet connection profile. The connection retrieves IPv4 addresses, IPv6 addresses, default gateway, routes, DNS servers, and search domains from a DHCP server and IPv6 stateless address autoconfiguration (SLAAC).

    The match parameter in this example defines that Ansible applies the play to devices that match PCI ID 0000:00:0[1-3].0, but not 0000:00:02.0. For further details about special modifiers and wild cards you can use, see the match parameter description in the /usr/share/ansible/roles/rhel-system-roles.network/README.md file.

  2. Validate the playbook syntax:

    # ansible-playbook ~/ethernet-dynamic-IP.yml --syntax-check

    Note that this command only validates the syntax and does not protect against a wrong but valid configuration.

  3. Run the playbook:

    # ansible-playbook ~/ethernet-dynamic-IP.yml

Additional resources

  • /usr/share/ansible/roles/rhel-system-roles.network/README.md file

2.12. Configuring multiple Ethernet interfaces by using a single connection profile by interface name

In most cases, one connection profile contains the settings of one network device. However, NetworkManager also supports wildcards when you set the interface name in connection profiles. If a host roams between Ethernet networks with dynamic IP address assignment, you can use this feature to create a single connection profile that you can use for multiple Ethernet interfaces.

Prerequisites

  • Multiple physical or virtual Ethernet devices exist in the server’s configuration.
  • A DHCP server is available in the network.
  • No connection profile exists on the host.

Procedure

  1. Add a connection profile that applies to all interface names starting with enp:

    # nmcli connection add con-name Example connection.multi-connect multiple match.interface-name enp* type ethernet

Verification

  1. Display all settings of the single connection profile:

    # nmcli connection show Example
    connection.id:                      Example
    ...
    connection.multi-connect:           3 (multiple)
    match.interface-name:               enp*
    ...

    3 indicates the number of interfaces active on the connection profile at the same time, and not the number of network interfaces in the connection profile. The connection profile uses all devices that match the pattern in the match.interface-name parameter and, therefore, the connection profiles have the same Universally Unique Identifier (UUID).

  2. Display the status of the connections:

    # nmcli connection show
    NAME                    UUID                    TYPE     DEVICE
    ...
    Example  6f22402e-c0cc-49cf-b702-eaf0cd5ea7d1  ethernet  enp7s0
    Example  6f22402e-c0cc-49cf-b702-eaf0cd5ea7d1  ethernet  enp8s0
    Example  6f22402e-c0cc-49cf-b702-eaf0cd5ea7d1  ethernet  enp9s0

Additional resources

  • nmcli(1) man page
  • nm-settings(5) man page

2.13. Configuring a single connection profile for multiple Ethernet interfaces using PCI IDs

The PCI ID is a unique identifier of the devices connected to the system. The connection profile adds multiple devices by matching interfaces based on a list of PCI IDs. You can use this procedure to connect multiple device PCI IDs to the single connection profile.

Prerequisites

  • Multiple physical or virtual Ethernet devices exist in the server’s configuration.
  • A DHCP server is available in the network.
  • No connection profile exists on the host.

Procedure

  1. Identify the device path. For example, to display the device paths of all interfaces starting with enp, enter :

    # udevadm info /sys/class/net/enp* | grep ID_PATH=
    ...
    E: ID_PATH=pci-0000:07:00.0
    E: ID_PATH=pci-0000:08:00.0
  2. Add a connection profile that applies to all PCI IDs matching the 0000:00:0[7-8].0 expression:

    # nmcli connection add type ethernet connection.multi-connect multiple match.path "pci-0000:07:00.0 pci-0000:08:00.0" con-name Example

Verification

  1. Display the status of the connection:

    # nmcli connection show
    NAME   UUID     TYPE        DEVICE
    Example      9cee0958-512f-4203-9d3d-b57af1d88466  ethernet  enp7s0
    Example      9cee0958-512f-4203-9d3d-b57af1d88466  ethernet  enp8s0
    ...
  2. To display all settings of the connection profile:

    # nmcli connection show Example
    connection.id:               Example
    ...
    connection.multi-connect:    3 (multiple)
    match.path:                  pci-0000:07:00.0,pci-0000:08:00.0
    ...

    This connection profile uses all devices with a PCI ID which match the pattern in the match.path parameter and, therefore, the connection profiles have the same Universally Unique Identifier (UUID).

Additional resources

  • nmcli(1) man page
  • nm-settings(5) man page

Chapter 3. Configuring network bonding

A network bond is a method to combine or aggregate physical and virtual network interfaces to provide a logical interface with higher throughput or redundancy. In a bond, the kernel handles all operations exclusively. You can create bonds on different types of devices, such as Ethernet devices or VLANs.

Red Hat Enterprise Linux provides administrators different options to configure team devices. For example:

  • Use nmcli to configure bond connections using the command line.
  • Use the RHEL web console to configure bond connections using a web browser.
  • Use nmtui to configure bond connections in a text-based user interface.
  • Use the nm-connection-editor application to configure bond connections in a graphical interface.
  • Use nmstatectl to configure bond connections through the Nmstate API.
  • Use RHEL System Roles to automate the bond configuration on one or multiple hosts.

3.1. Understanding the default behavior of controller and port interfaces

Consider the following default behavior when managing or troubleshooting team or bond port interfaces using the NetworkManager service:

  • Starting the controller interface does not automatically start the port interfaces.
  • Starting a port interface always starts the controller interface.
  • Stopping the controller interface also stops the port interface.
  • A controller without ports can start static IP connections.
  • A controller without ports waits for ports when starting DHCP connections.
  • A controller with a DHCP connection waiting for ports completes when you add a port with a carrier.
  • A controller with a DHCP connection waiting for ports continues waiting when you add a port without carrier.

3.2. Upstream switch configuration depending on the bonding modes

Depending on the bonding mode you want to use, you must configure the ports on the switch:

Bonding modeConfiguration on the switch

0 - balance-rr

Requires static EtherChannel enabled, not Link Aggregation Control Protocol (LACP)-negotiated.

1 - active-backup

No configuration required on the switch.

2 - balance-xor

Requires static EtherChannel enabled, not LACP-negotiated.

3 - broadcast

Requires static EtherChannel enabled, not LACP-negotiated.

4 - 802.3ad

Requires LACP-negotiated EtherChannel enabled.

5 - balance-tlb

No configuration required on the switch.

6 - balance-alb

No configuration required on the switch.

For details how to configure your switch, see the documentation of the switch.

Important

Certain network bonding features, such as the fail-over mechanism, do not support direct cable connections without a network switch. For further details, see the Is bonding supported with direct connection using crossover cables? KCS solution.

3.3. Configuring a network bond by using nmcli

To configure a network bond on the command line, use the nmcli utility.

Prerequisites

Procedure

  1. Create a bond interface:

    # nmcli connection add type bond con-name bond0 ifname bond0 bond.options "mode=active-backup"

    This command creates a bond named bond0 that uses the active-backup mode.

    To additionally set a Media Independent Interface (MII) monitoring interval, add the miimon=interval option to the bond.options property, for example:

    # nmcli connection add type bond con-name bond0 ifname bond0 bond.options "mode=active-backup,miimon=1000"
  2. Display the network interfaces, and note names of interfaces you plan to add to the bond:

    # nmcli device status
    DEVICE   TYPE      STATE         CONNECTION
    enp7s0   ethernet  disconnected  --
    enp8s0   ethernet  disconnected  --
    bridge0  bridge    connected     bridge0
    bridge1  bridge    connected     bridge1
    ...

    In this example:

    • enp7s0 and enp8s0 are not configured. To use these devices as ports, add connection profiles in the next step.
    • bridge0 and bridge1 have existing connection profiles. To use these devices as ports, modify their profiles in the next step.
  3. Assign interfaces to the bond:

    1. If the interfaces you want to assign to the bond are not configured, create new connection profiles for them:

      # nmcli connection add type ethernet slave-type bond con-name bond0-port1 ifname enp7s0 master bond0
      # nmcli connection add type ethernet slave-type bond con-name bond0-port2 ifname enp8s0 master bond0

      These commands create profiles for enp7s0 and enp8s0, and add them to the bond0 connection.

    2. To assign an existing connection profile to the bond:

      1. Set the master parameter of these connections to bond0:

        # nmcli connection modify bridge0 master bond0
        # nmcli connection modify bridge1 master bond0

        These commands assign the existing connection profiles named bridge0 and bridge1 to the bond0 connection.

      2. Reactivate the connections:

        # nmcli connection up bridge0
        # nmcli connection up bridge1
  4. Configure the IPv4 settings:

    • To use this bond device as a port of other devices, enter:

      # nmcli connection modify bond0 ipv4.method disabled
    • To use DHCP, no action is required.
    • To set a static IPv4 address, network mask, default gateway, and DNS server to the bond0 connection, enter:

      # nmcli connection modify bond0 ipv4.addresses '192.0.2.1/24' ipv4.gateway '192.0.2.254' ipv4.dns '192.0.2.253' ipv4.dns-search 'example.com' ipv4.method manual
  5. Configure the IPv6 settings:

    • To use this bond device as a port of other devices, enter:

      # nmcli connection modify bond0 ipv6.method disabled
    • To use DHCP, no action is required.
    • To set a static IPv6 address, network mask, default gateway, and DNS server to the bond0 connection, enter:

      # nmcli connection modify bond0 ipv6.addresses '2001:db8:1::1/64' ipv6.gateway '2001:db8:1::fffe' ipv6.dns '2001:db8:1::fffd' ipv6.dns-search 'example.com' ipv6.method manual
  6. Optional: If you want to set any parameters on the bond ports, use the following command:

    # nmcli connection modify bond0-port1 bond-port.<parameter> <value>
  7. Activate the connection:

    # nmcli connection up bond0
  8. Verify that the ports are connected, and the CONNECTION column displays the port’s connection name:

    # nmcli device
    DEVICE   TYPE      STATE      CONNECTION
    ...
    enp7s0   ethernet  connected  bond0-port1
    enp8s0   ethernet  connected  bond0-port2

    When you activate any port of the connection, NetworkManager also activates the bond, but not the other ports of it. You can configure that Red Hat Enterprise Linux enables all ports automatically when the bond is enabled:

    1. Enable the connection.autoconnect-slaves parameter of the bond’s connection:

      # nmcli connection modify bond0 connection.autoconnect-slaves 1
    2. Reactivate the bridge:

      # nmcli connection up bond0

Verification

  1. Temporarily remove the network cable from the host.

    Note that there is no method to properly test link failure events using software utilities. Tools that deactivate connections, such as nmcli, show only the bonding driver’s ability to handle port configuration changes and not actual link failure events.

  2. Display the status of the bond:

    # cat /proc/net/bonding/bond0

3.4. Configuring a network bond by using the RHEL web console

Use the RHEL web console to configure a network bond if you prefer to manage network settings using a web browser-based interface.

Prerequisites

Procedure

  1. Select the Networking tab in the navigation on the left side of the screen.
  2. Click Add bond in the Interfaces section.
  3. Enter the name of the bond device you want to create.
  4. Select the interfaces that should be members of the bond.
  5. Select the mode of the bond.

    If you select Active backup, the web console shows the additional field Primary in which you can select the preferred active device.

  6. Set the link monitoring mode. For example, when you use the Adaptive load balancing mode, set it to ARP.
  7. Optional: Adjust the monitoring interval, link up delay, and link down delay settings. Typically, you only change the defaults for troubleshooting purposes.

    bond settings
  8. Click Apply.
  9. By default, the bond uses a dynamic IP address. If you want to set a static IP address:

    1. Click the name of the bond in the Interfaces section.
    2. Click Edit next to the protocol you want to configure.
    3. Select Manual next to Addresses, and enter the IP address, prefix, and default gateway.
    4. In the DNS section, click the + button, and enter the IP address of the DNS server. Repeat this step to set multiple DNS servers.
    5. In the DNS search domains section, click the + button, and enter the search domain.
    6. If the interface requires static routes, configure them in the Routes section.

      bond team bridge vlan.ipv4
    7. Click Apply

Verification

  1. Select the Networking tab in the navigation on the left side of the screen, and check if there is incoming and outgoing traffic on the interface:

    bond verify
  2. Temporarily remove the network cable from the host.

    Note that there is no method to properly test link failure events using software utilities. Tools that deactivate connections, such as the web console, show only the bonding driver’s ability to handle member configuration changes and not actual link failure events.

  3. Display the status of the bond:

    # cat /proc/net/bonding/bond0

3.5. Configuring a network bond by using nmtui

The nmtui application provides a text-based user interface for NetworkManager. You can use nmtui to configure a network bond on a host without a graphical interface.

Note

In nmtui:

  • Navigate by using the cursor keys.
  • Press a button by selecting it and hitting Enter.
  • Select and deselect checkboxes by using Space.

Prerequisites

  • Two or more physical or virtual network devices are installed on the server.
  • To use Ethernet devices as ports of the bond, the physical or virtual Ethernet devices must be installed on the server.

Procedure

  1. If you do not know the network device names on which you want configure a network bond, display the available devices:

    # nmcli device status
    DEVICE     TYPE      STATE                   CONNECTION
    enp7s0     ethernet  unavailable             --
    enp8s0     ethernet  unavailable             --
    ...
  2. Start nmtui:

    # nmtui
  3. Select Edit a connection, and press Enter.
  4. Press the Add button.
  5. Select Bond from the list of network types, and press Enter.
  6. Optional: Enter a name for the NetworkManager profile to be created.

    On hosts with multiple profiles, a meaningful name makes it easier to identify the purpose of a profile.

  7. Enter the bond device name to be created into the Device field.
  8. Add ports to the bond to be created:

    1. Press the Add button next to the Slaves list.
    2. Select the type of the interface you want to add as port to the bond, for example, Ethernet.
    3. Optional: Enter a name for the NetworkManager profile to be created for this bond port.
    4. Enter the port’s device name into the Device field.
    5. Press the OK button to return to the window with the bond settings.

      Figure 3.1. Adding an Ethernet device as port to a bond

      nmtui bond add port
    6. Repeat these steps to add more ports to the bond.
  9. Set the bond mode. Depending on the value you set, nmtui displays additional fields for settings that are related to the selected mode.
  10. Depending on your environment, configure the IP address settings in the IPv4 configuration and IPv6 configuration areas accordingly. For this, press the button next to these areas, and select:

    • Disabled, if the bond does not require an IP address.
    • Automatic, if a DHCP server or stateless address autoconfiguration (SLAAC) dynamically assigns an IP address to the bond.
    • Manual, if the network requires static IP address settings. In this case, you must fill further fields:

      1. Press the Show button next to the protocol you want to configure to display additional fields.
      2. Press the Add button next to Addresses, and enter the IP address and the subnet mask in Classless Inter-Domain Routing (CIDR) format.

        If you do not specify a subnet mask, NetworkManager sets a /32 subnet mask for IPv4 addresses and /64 for IPv6 addresses.

      3. Enter the address of the default gateway.
      4. Press the Add button next to DNS servers, and enter the DNS server address.
      5. Press the Add button next to Search domains, and enter the DNS search domain.

    Figure 3.2. Example of a bond connection with static IP address settings

    nmtui bond static IP
  11. Press the OK button to create and automatically activate the new connection.
  12. Press the Back button to return to the main menu.
  13. Select Quit, and press Enter to close the nmtui application.

Verification

  1. Temporarily remove the network cable from the host.

    Note that there is no method to properly test link failure events using software utilities. Tools that deactivate connections, such as nmcli, show only the bonding driver’s ability to handle port configuration changes and not actual link failure events.

  2. Display the status of the bond:

    # cat /proc/net/bonding/bond0

3.6. Configuring a network bond by using nm-connection-editor

If you use Red Hat Enterprise Linux with a graphical interface, you can configure network bonds using the nm-connection-editor application.

Note that nm-connection-editor can add only new ports to a bond. To use an existing connection profile as a port, create the bond by using the nmcli utility as described in Configuring a network bond by using nmcli.

Prerequisites

  • Two or more physical or virtual network devices are installed on the server.
  • To use Ethernet devices as ports of the bond, the physical or virtual Ethernet devices must be installed on the server.
  • To use team, bond, or VLAN devices as ports of the bond, ensure that these devices are not already configured.

Procedure

  1. Open a terminal, and enter nm-connection-editor:

    $ nm-connection-editor
  2. Click the + button to add a new connection.
  3. Select the Bond connection type, and click Create.
  4. On the Bond tab:

    1. Optional: Set the name of the bond interface in the Interface name field.
    2. Click the Add button to add a network interface as a port to the bond.

      1. Select the connection type of the interface. For example, select Ethernet for a wired connection.
      2. Optional: Set a connection name for the port.
      3. If you create a connection profile for an Ethernet device, open the Ethernet tab, and select in the Device field the network interface you want to add as a port to the bond. If you selected a different device type, configure it accordingly. Note that you can only use Ethernet interfaces in a bond that are not configured.
      4. Click Save.
    3. Repeat the previous step for each interface you want to add to the bond:

      add nic to bond in nm connection editor

    4. Optional: Set other options, such as the Media Independent Interface (MII) monitoring interval.
  5. Configure the IP address settings on both the IPv4 Settings and IPv6 Settings tabs:

    • To use this bridge device as a port of other devices, set the Method field to Disabled.
    • To use DHCP, leave the Method field at its default, Automatic (DHCP).
    • To use static IP settings, set the Method field to Manual and fill the fields accordingly:

      bond IP settings nm connection editor

  6. Click Save.
  7. Close nm-connection-editor.

Verification

  1. Temporarily remove the network cable from the host.

    Note that there is no method to properly test link failure events using software utilities. Tools that deactivate connections, such as nmcli, show only the bonding driver’s ability to handle port configuration changes and not actual link failure events.

  2. Display the status of the bond:

    # cat /proc/net/bonding/bond0

3.7. Configuring a network bond by using nmstatectl

Use the nmstatectl utility to configure a network bond through the Nmstate API. The Nmstate API ensures that, after setting the configuration, the result matches the configuration file. If anything fails, nmstatectl automatically rolls back the changes to avoid leaving the system in an incorrect state.

Depending on your environment, adjust the YAML file accordingly. For example, to use different devices than Ethernet adapters in the bond, adapt the base-iface attribute and type attributes of the ports you use in the bond.

Prerequisites

  • Two or more physical or virtual network devices are installed on the server.
  • To use Ethernet devices as ports in the bond, the physical or virtual Ethernet devices must be installed on the server.
  • To use team, bridge, or VLAN devices as ports in the bond, set the interface name in the port list, and define the corresponding interfaces.
  • The nmstate package is installed.

Procedure

  1. Create a YAML file, for example ~/create-bond.yml, with the following content:

    ---
    interfaces:
    - name: bond0
      type: bond
      state: up
      ipv4:
        enabled: true
        address:
        - ip: 192.0.2.1
          prefix-length: 24
        dhcp: false
      ipv6:
        enabled: true
        address:
        - ip: 2001:db8:1::1
          prefix-length: 64
        autoconf: false
        dhcp: false
      link-aggregation:
        mode: active-backup
        port:
        - enp1s0
        - enp7s0
    - name: enp1s0
      type: ethernet
      state: up
    - name: enp7s0
      type: ethernet
      state: up
    
    routes:
      config:
      - destination: 0.0.0.0/0
        next-hop-address: 192.0.2.254
        next-hop-interface: bond0
      - destination: ::/0
        next-hop-address: 2001:db8:1::fffe
        next-hop-interface: bond0
    
    dns-resolver:
      config:
        search:
        - example.com
        server:
        - 192.0.2.200
        - 2001:db8:1::ffbb

    These settings define a network bond with the following settings:

    • Network interfaces in the bond: enp1s0 and enp7s0
    • Mode: active-backup
    • Static IPv4 address: 192.0.2.1 with a /24 subnet mask
    • Static IPv6 address: 2001:db8:1::1 with a /64 subnet mask
    • IPv4 default gateway: 192.0.2.254
    • IPv6 default gateway: 2001:db8:1::fffe
    • IPv4 DNS server: 192.0.2.200
    • IPv6 DNS server: 2001:db8:1::ffbb
    • DNS search domain: example.com
  2. Apply the settings to the system:

    # nmstatectl apply ~/create-bond.yml

Verification

  1. Display the status of the devices and connections:

    # nmcli device status
    DEVICE      TYPE      STATE      CONNECTION
    bond0       bond      connected  bond0
  2. Display all settings of the connection profile:

    # nmcli connection show bond0
    connection.id:              bond0
    connection.uuid:            79cbc3bd-302e-4b1f-ad89-f12533b818ee
    connection.stable-id:       --
    connection.type:            bond
    connection.interface-name:  bond0
    ...
  3. Display the connection settings in YAML format:

    # nmstatectl show bond0

Additional resources

  • nmstatectl(8) man page
  • /usr/share/doc/nmstate/examples/ directory

3.8. Configuring a network bond by using the network RHEL System Role

You can remotely configure a network bond by using the network RHEL System Role.

Perform this procedure on the Ansible control node.

Prerequisites

  • You have prepared the control node and the managed nodes
  • You are logged in to the control node as a user who can run playbooks on the managed nodes.
  • The account you use to connect to the managed nodes has sudo permissions on them.
  • The managed nodes or groups of managed nodes on which you want to run this playbook are listed in the Ansible inventory file.
  • Two or more physical or virtual network devices are installed on the server.

Procedure

  1. Create a playbook file, for example ~/bond-ethernet.yml, with the following content:

    ---
    - name: Configure the network
      hosts: managed-node-01.example.com
      tasks:
      - name: Configure a network bond that uses two Ethernet ports
        include_role:
          name: rhel-system-roles.network
    
        vars:
          network_connections:
            # Define the bond profile
            - name: bond0
              type: bond
              interface_name: bond0
              ip:
                address:
                  - "192.0.2.1/24"
                  - "2001:db8:1::1/64"
                gateway4: 192.0.2.254
                gateway6: 2001:db8:1::fffe
                dns:
                  - 192.0.2.200
                  - 2001:db8:1::ffbb
                dns_search:
                  - example.com
              bond:
                mode: active-backup
              state: up
    
            # Add an Ethernet profile to the bond
            - name: bond0-port1
              interface_name: enp7s0
              type: ethernet
              controller: bond0
              state: up
    
            # Add a second Ethernet profile to the bond
            - name: bond0-port2
              interface_name: enp8s0
              type: ethernet
              controller: bond0
              state: up

    These settings define a network bond with the following settings:

    • A static IPv4 address - 192.0.2.1 with a /24 subnet mask
    • A static IPv6 address - 2001:db8:1::1 with a /64 subnet mask
    • An IPv4 default gateway - 192.0.2.254
    • An IPv6 default gateway - 2001:db8:1::fffe
    • An IPv4 DNS server - 192.0.2.200
    • An IPv6 DNS server - 2001:db8:1::ffbb
    • A DNS search domain - example.com
    • Ports of the bond - enp7s0 and enp8s0
    • Bond mode - active-backup

      Note

      Set the IP configuration on the bond and not on the ports of the Linux bond.

  2. Validate the playbook syntax:

    # ansible-playbook ~/bond-ethernet.yml --syntax-check

    Note that this command only validates the syntax and does not protect against a wrong but valid configuration.

  3. Run the playbook:

    # ansible-playbook ~/bond-ethernet.yml

Additional resources

  • /usr/share/ansible/roles/rhel-system-roles.network/README.md file

3.9. Creating a network bond to enable switching between an Ethernet and wireless connection without interrupting the VPN

RHEL users who connect their workstation to their company’s network typically use a VPN to access remote resources. However, if the workstation switches between an Ethernet and Wi-Fi connection, for example, if you release a laptop from a docking station with an Ethernet connection, the VPN connection is interrupted. To avoid this problem, you can create a network bond that uses the Ethernet and Wi-Fi connection in active-backup mode.

Prerequisites

  • The host contains an Ethernet and a Wi-Fi device.
  • An Ethernet and Wi-Fi NetworkManager connection profile has been created and both connections work independently.

    This procedure uses the following connection profiles to create a network bond named bond0:

    • Docking_station associated with the enp11s0u1 Ethernet device
    • Wi-Fi associated with the wlp1s0 Wi-Fi device

Procedure

  1. Create a bond interface in active-backup mode:

    # nmcli connection add type bond con-name bond0 ifname bond0 bond.options "mode=active-backup"

    This command names both the interface and connection profile bond0.

  2. Configure the IPv4 settings of the bond:

    • If a DHCP server in your network assigns IPv4 addresses to hosts, no action is required.
    • If your local network requires static IPv4 addresses, set the address, network mask, default gateway, DNS server, and DNS search domain to the bond0 connection:

      # nmcli connection modify bond0 ipv4.addresses '192.0.2.1/24'
      # nmcli connection modify bond0 ipv4.gateway '192.0.2.254'
      # nmcli connection modify bond0 ipv4.dns '192.0.2.253'
      # nmcli connection modify bond0 ipv4.dns-search 'example.com'
      # nmcli connection modify bond0 ipv4.method manual
  3. Configure the IPv6 settings of the bond:

    • If your router or a DHCP server in your network assigns IPv6 addresses to hosts, no action is required.
    • If your local network requires static IPv6 addresses, set the address, network mask, default gateway, DNS server, and DNS search domain to the bond0 connection:

      # nmcli connection modify bond0 ipv6.addresses '2001:db8:1::1/64'
      # nmcli connection modify bond0 ipv6.gateway '2001:db8:1::fffe'
      # nmcli connection modify bond0 ipv6.dns '2001:db8:1::fffd'
      # nmcli connection modify bond0 ipv6.dns-search 'example.com'
      # nmcli connection modify bond0 ipv6.method manual
  4. Display the connection profiles:

    # nmcli connection show
    NAME             UUID                                  TYPE      DEVICE
    Docking_station  256dd073-fecc-339d-91ae-9834a00407f9  ethernet  enp11s0u1
    Wi-Fi            1f1531c7-8737-4c60-91af-2d21164417e8  wifi      wlp1s0
    ...

    You require the names of the connection profiles and the Ethernet device name in the next steps.

  5. Assign the connection profile of the Ethernet connection to the bond:

    # nmcli connection modify Docking_station master bond0
  6. Assign the connection profile of the Wi-Fi connection to the bond:

    # nmcli connection modify Wi-Fi master bond0
  7. If your Wi-Fi network uses MAC filtering to allow only MAC addresses on a allow list to access the network, configure that NetworkManager dynamically assigns the MAC address of the active port to the bond:

    # nmcli connection modify bond0 +bond.options fail_over_mac=1

    With this setting, you must set only the MAC address of the Wi-Fi device to the allow list instead of the MAC address of both the Ethernet and Wi-Fi device.

  8. Set the device associated with the Ethernet connection as primary device of the bond:

    # nmcli con modify bond0 +bond.options "primary=enp11s0u1"

    With this setting, the bond always uses the Ethernet connection if it is available.

  9. Configure that NetworkManager automatically activates ports when the bond0 device is activated:

    # nmcli connection modify bond0 connection.autoconnect-slaves 1
  10. Activate the bond0 connection:

    # nmcli connection up bond0

Verification

  • Display the currently active device, the status of the bond and its ports:

    # cat /proc/net/bonding/bond0
    Ethernet Channel Bonding Driver: v3.7.1 (April 27, 2011)
    
    Bonding Mode: fault-tolerance (active-backup) (fail_over_mac active)
    Primary Slave: enp11s0u1 (primary_reselect always)
    Currently Active Slave: enp11s0u1
    MII Status: up
    MII Polling Interval (ms): 1
    Up Delay (ms): 0
    Down Delay (ms): 0
    Peer Notification Delay (ms): 0
    
    Slave Interface: enp11s0u1
    MII Status: up
    Speed: 1000 Mbps
    Duplex: full
    Link Failure Count: 0
    Permanent HW addr: 00:53:00:59:da:b7
    Slave queue ID: 0
    
    Slave Interface: wlp1s0
    MII Status: up
    Speed: Unknown
    Duplex: Unknown
    Link Failure Count: 2
    Permanent HW addr: 00:53:00:b3:22:ba
    Slave queue ID: 0

3.10. The different network bonding modes

The Linux bonding driver provides link aggregation. Bonding is the process of aggregating multiple network interfaces in parallel to provide a single logical bonded interface. The actions of a bonded interface depend on the bonding policy that is also known as mode. The different modes provide either load-balancing or hot standby services.

The following modes exist:

Balance-rr (Mode 0)

Balance-rr uses the round-robin algorithm that sequentially transmits packets from the first available port to the last one. This mode provides load balancing and fault tolerance.

This mode requires switch configuration of a port aggregation group, also called EtherChannel or similar port grouping. An EtherChannel is a port link aggregation technology to group multiple physical Ethernet links to one logical Ethernet link.

The drawback of this mode is that it is not suitable for heavy workloads and if TCP throughput or ordered packet delivery is essential.

Active-backup (Mode 1)

Active-backup uses the policy that determines that only one port is active in the bond. This mode provides fault tolerance and does not require any switch configuration.

If the active port fails, an alternate port becomes active. The bond sends a gratuitous address resolution protocol (ARP) response to the network. The gratuitous ARP forces the receiver of the ARP frame to update their forwarding table. The Active-backup mode transmits a gratuitous ARP to announce the new path to maintain connectivity for the host.

The primary option defines the preferred port of the bonding interface.

Balance-xor (Mode 2)

Balance-xor uses the selected transmit hash policy to send the packets. This mode provides load balancing, fault tolerance, and requires switch configuration to set up an Etherchannel or similar port grouping.

To alter packet transmission and balance transmit, this mode uses the xmit_hash_policy option. Depending on the source or destination of traffic on the interface, the interface requires an additional load-balancing configuration. See description xmit_hash_policy bonding parameter.

Broadcast (Mode 3)

Broadcast uses a policy that transmits every packet on all interfaces. This mode provides fault tolerance and requires a switch configuration to set up an EtherChannel or similar port grouping.

The drawback of this mode is that it is not suitable for heavy workloads and if TCP throughput or ordered packet delivery is essential.

802.3ad (Mode 4)

802.3ad uses the same-named IEEE standard dynamic link aggregation policy. This mode provides fault tolerance. This mode requires switch configuration to set up a Link Aggregation Control Protocol (LACP) port grouping.

This mode creates aggregation groups that share the same speed and duplex settings and utilizes all ports in the active aggregator. Depending on the source or destination of traffic on the interface, this mode requires an additional load-balancing configuration.

By default, the port selection for outgoing traffic depends on the transmit hash policy. Use the xmit_hash_policy option of the transmit hash policy to change the port selection and balance transmit.

The difference between the 802.3ad and the Balance-xor is compliance. The 802.3ad policy negotiates LACP between the port aggregation groups. See description xmit_hash_policy bonding parameter

Balance-tlb (Mode 5)

Balance-tlb uses the transmit load balancing policy. This mode provides fault tolerance, load balancing, and establishes channel bonding that does not require any switch support.

The active port receives the incoming traffic. In case of failure of the active port, another one takes over the MAC address of the failed port. To decide which interface processes the outgoing traffic, use one of the following modes:

  • Value 0: Uses the hash distribution policy to distribute traffic without load balancing
  • Value 1: Distributes traffic to each port by using load balancing

    With the bonding option tlb_dynamic_lb=0, this bonding mode uses the xmit_hash_policy bonding option to balance transmit. The primary option defines the preferred port of the bonding interface.

See description xmit_hash_policy bonding parameter.

Balance-alb (Mode 6)

Balance-alb uses an adaptive load balancing policy. This mode provides fault tolerance, load balancing, and does not require any special switch support.

This mode Includes balance-transmit load balancing (balance-tlb) and receive-load balancing for IPv4 and IPv6 traffic. The bonding intercepts ARP replies sent by the local system and overwrites the source hardware address of one of the ports in the bond. ARP negotiation manages the receive-load balancing. Therefore, different ports use different hardware addresses for the server.

The primary option defines the preferred port of the bonding interface. With the bonding option tlb_dynamic_lb=0, this bonding mode uses the xmit_hash_policy bonding option to balance transmit. See description xmit_hash_policy bonding parameter.

Additional resources

3.11. The xmit_hash_policy bonding parameter

The xmit_hash_policy load balancing parameter selects the transmit hash policy for a node selection in the balance-xor, 802.3ad, balance-alb, and balance-tlb modes. It is only applicable to mode 5 and 6 if the tlb_dynamic_lb parameter is 0. The possible values of this parameter are layer2, layer2+3, layer3+4, encap2+3, encap3+4, and vlan+srcmac.

Refer the table for details:

Policy or Network layers

Layer2

Layer2+3

Layer3+4

encap2+3

encap3+4

VLAN+srcmac

Uses

XOR of source and destination MAC addresses and Ethernet protocol type

XOR of source and destination MAC addresses and IP addresses

XOR of source and destination ports and IP addresses

XOR of source and destination MAC addresses and IP addresses inside a supported tunnel, for example, Virtual Extensible LAN (VXLAN). This mode relies on skb_flow_dissect() function to obtain the header fields

XOR of source and destination ports and IP addresses inside a supported tunnel, for example, VXLAN. This mode relies on skb_flow_dissect() function to obtain the header fields

XOR of VLAN ID and source MAC vendor and source MAC device

Placement of traffic

All traffic to a particular network peer on the same underlying network interface

All traffic to a particular IP address on the same underlying network interface

All traffic to a particular IP address and port on the same underlying network interface

   

Primary choice

If network traffic is between this system and multiple other systems in the same broadcast domain

If network traffic between this system and multiple other systems goes through a default gateway

If network traffic between this system and another system uses the same IP addresses but goes through multiple ports

The encapsulated traffic is between the source system and multiple other systems using multiple IP addresses

The encapsulated traffic is between the source system and other systems using multiple port numbers

If the bond carries network traffic, from multiple containers or virtual machines (VM), that expose their MAC address directly to the external network such as the bridge network, and you can not configure a switch for Mode 2 or Mode 4

Secondary choice

If network traffic is mostly between this system and multiple other systems behind a default gateway

If network traffic is mostly between this system and another system

    

Compliant

802.3ad

802.3ad

Not 802.3ad

   

Default policy

This is the default policy if no configuration is provided

For non-IP traffic, the formula is the same as for the layer2 transmit policy

For non-IP traffic, the formula is the same as for the layer2 transmit policy

   

Chapter 4. Configuring network teaming

A network team is a method to combine or aggregate physical and virtual network interfaces to provide a logical interface with higher throughput or redundancy. Network teaming uses a small kernel module to implement fast handling of packet flows and a user-space service for other tasks. This way, network teaming is an easily extensible and scalable solution for load-balancing and redundancy requirements.

Red Hat Enterprise Linux provides administrators different options to configure team devices. For example:

  • Use nmcli to configure teams connections using the command line.
  • Use the RHEL web console to configure team connections using a web browser.
  • Use the nm-connection-editor application to configure team connections in a graphical interface.
Important

Network teaming is deprecated in Red Hat Enterprise Linux 9. Consider using the network bonding driver as an alternative. For details, see Configuring network bonding.

4.1. Migrating a network team configuration to network bond

Network teaming is deprecated in Red Hat Enterprise Linux 9. If you already have a working network team configured, for example because you upgraded from an earlier RHEL version, you can migrate the configuration to a network bond that is managed by NetworkManager.

Important

The team2bond utility only converts the network team configuration to a bond. Afterwards, you must manually configure further settings of the bond, such as IP addresses and DNS configuration.

Prerequisites

  • The team-team0 NetworkManager connection profile is configured and manages the team0 device.
  • The teamd package is installed.

Procedure

  1. Optional: Display the IP configuration of the team-team0 NetworkManager connection:

    # nmcli connection show team-team0 | egrep "^ip"
    ...
    ipv4.method:                            manual
    ipv4.dns:                               192.0.2.253
    ipv4.dns-search:                        example.com
    ipv4.addresses:                         192.0.2.1/24
    ipv4.gateway:                           192.0.2.254
    ...
    ipv6.method:                            manual
    ipv6.dns:                               2001:db8:1::fffd
    ipv6.dns-search:                        example.com
    ipv6.addresses:                         2001:db8:1::1/64
    ipv6.gateway:                           2001:db8:1::fffe
    ...
  2. Export the configuration of the team0 device to a JSON file:

    # teamdctl team0 config dump actual > /tmp/team0.json
  3. Remove the network team. For example, if you configured the team in NetworkManager, remove the team-team0 connection profile and the profiles of associated ports:

    # nmcli connection delete team-team0
    # nmcli connection delete team-team0-port1
    # nmcli connection delete team-team0-port2
  4. Run the team2bond utility in dry-run mode to display nmcli commands that set up a network bond with similar settings as the team device:

    # team2bond --config=/tmp/team0.json --rename=bond0
    nmcli con add type bond ifname bond0 bond.options "mode=active-backup,num_grat_arp=1,num_unsol_na=1,resend_igmp=1,miimon=100,miimon=100"
    nmcli con add type ethernet ifname enp7s0 master bond0
    nmcli con add type ethernet ifname enp8s0 master bond0

    The first command contains two miimon options because the team configuration file contained two link_watch entries. Note that this does not affect the creation of the bond.

    If you bound services to the device name of the team and want to avoid updating or breaking these services, omit the --rename=bond0 option. In this case, team2bond uses the same interface name for the bond as for the team.

  5. Verify that the options for the bond the team2bond utility suggested are correct.
  6. Create the bond. You can execute the suggested nmcli commands or re-run the team2bond command with the --exec-cmd option:

    # team2bond --config=/tmp/team0.json --rename=bond0 --exec-cmd
    Connection 'bond-bond0' (0241a531-0c72-4202-80df-73eadfc126b5) successfully added.
    Connection 'bond-slave-enp7s0' (38489729-b624-4606-a784-1ccf01e2f6d6) successfully added.
    Connection 'bond-slave-enp8s0' (de97ec06-7daa-4298-9a71-9d4c7909daa1) successfully added.

    You require the name of the bond connection profile (bond-bond0) in the next steps.

  7. Set the IPv4 settings that were previously configured on team-team0 to the bond-bond0 connection:

    # nmcli connection modify bond-bond0 ipv4.addresses '192.0.2.1/24'
    # nmcli connection modify bond-bond0 ipv4.gateway '192.0.2.254'
    # nmcli connection modify bond-bond0 ipv4.dns '192.0.2.253'
    # nmcli connection modify bond-bond0 ipv4.dns-search 'example.com'
    # nmcli connection modify bond-bond0 ipv4.method manual
  8. Set the IPv6 settings that were previously configured on team-team0 to the bond-bond0 connection:

    # nmcli connection modify bond-bond0 ipv6.addresses '2001:db8:1::1/64'
    # nmcli connection modify bond-bond0 ipv6.gateway '2001:db8:1::fffe'
    # nmcli connection modify bond-bond0 ipv6.dns '2001:db8:1::fffd'
    # nmcli connection modify bond-bond0 ipv6.dns-search 'example.com'
    # nmcli connection modify bond-bond0 ipv6.method manual
  9. Activate the connection:

    # nmcli connection up bond-bond0

Verification

  1. Display the IP configuration of the bond-bond0 NetworkManager connection:

    # nmcli connection show bond-bond0 | egrep "^ip"
    ...
    ipv4.method:                            manual
    ipv4.dns:                               192.0.2.253
    ipv4.dns-search:                        example.com
    ipv4.addresses:                         192.0.2.1/24
    ipv4.gateway:                           192.0.2.254
    ...
    ipv6.method:                            manual
    ipv6.dns:                               2001:db8:1::fffd
    ipv6.dns-search:                        example.com
    ipv6.addresses:                         2001:db8:1::1/64
    ipv6.gateway:                           2001:db8:1::fffe
    ...
  2. Display the status of the bond:

    # cat /proc/net/bonding/bond0
    Ethernet Channel Bonding Driver: v5.13.0-0.rc7.51.el9.x86_64
    
    Bonding Mode: fault-tolerance (active-backup)
    Primary Slave: None
    Currently Active Slave: enp7s0
    MII Status: up
    MII Polling Interval (ms): 100
    Up Delay (ms): 0
    Down Delay (ms): 0
    Peer Notification Delay (ms): 0
    
    Slave Interface: enp7s0
    MII Status: up
    Speed: Unknown
    Duplex: Unknown
    Link Failure Count: 0
    Permanent HW addr: 52:54:00:bf:b1:a9
    Slave queue ID: 0
    
    Slave Interface: enp8s0
    MII Status: up
    Speed: Unknown
    Duplex: Unknown
    Link Failure Count: 0
    Permanent HW addr: 52:54:00:04:36:0f
    Slave queue ID: 0

    In this example, both ports are up.

  3. To verify that bonding failover works:

    1. Temporarily remove the network cable from the host. Note that there is no method to properly test link failure events using the command line.
    2. Display the status of the bond:

      # cat /proc/net/bonding/bond0

4.2. Understanding the default behavior of controller and port interfaces

Consider the following default behavior when managing or troubleshooting team or bond port interfaces using the NetworkManager service:

  • Starting the controller interface does not automatically start the port interfaces.
  • Starting a port interface always starts the controller interface.
  • Stopping the controller interface also stops the port interface.
  • A controller without ports can start static IP connections.
  • A controller without ports waits for ports when starting DHCP connections.
  • A controller with a DHCP connection waiting for ports completes when you add a port with a carrier.
  • A controller with a DHCP connection waiting for ports continues waiting when you add a port without carrier.

4.4. Configuring a network team by using nmcli

To configure a network team on the command line, use the nmcli utility.

Important

Network teaming is deprecated in Red Hat Enterprise Linux 9. Consider using the network bonding driver as an alternative. For details, see Configuring network bonding.

Prerequisites

Procedure

  1. Create a team interface:

    # nmcli connection add type team con-name team0 ifname team0 team.runner activebackup

    This command creates a network team named team0 that uses the activebackup runner.

  2. Optionally, set a link watcher. For example, to set the ethtool link watcher in the team0 connection profile:

    # nmcli connection modify team0 team.link-watchers "name=ethtool"

    Link watchers support different parameters. To set parameters for a link watcher, specify them space-separated in the name property. Note that the name property must be surrounded by quotation marks. For example, to use the ethtool link watcher and set its delay-up parameter to 2500 milliseconds (2.5 seconds):

    # nmcli connection modify team0 team.link-watchers "name=ethtool delay-up=2500"

    To set multiple link watchers and each of them with specific parameters, the link watchers must be separated by a comma. The following example sets the ethtool link watcher with the delay-up parameter and the arp_ping link watcher with the source-host and target-host parameter:

    # nmcli connection modify team0 team.link-watchers "name=ethtool delay-up=2, name=arp_ping source-host=192.0.2.1 target-host=192.0.2.2"
  3. Display the network interfaces, and note the names of the interfaces you want to add to the team:

    # nmcli device status
    DEVICE  TYPE      STATE         CONNECTION
    enp7s0  ethernet  disconnected  --
    enp8s0  ethernet  disconnected  --
    bond0   bond      connected  bond0
    bond1   bond      connected  bond1
    ...

    In this example:

    • enp7s0 and enp8s0 are not configured. To use these devices as ports, add connection profiles in the next step. Note that you can only use Ethernet interfaces in a team that are not assigned to any connection.
    • bond0 and bond1 have existing connection profiles. To use these devices as ports, modify their profiles in the next step.
  4. Assign the port interfaces to the team:

    1. If the interfaces you want to assign to the team are not configured, create new connection profiles for them:

      # nmcli connection add type ethernet slave-type team con-name team0-port1 ifname enp7s0 master team0
      # nmcli connection add type ethernet slave-type team con-name team0-port2 ifname enp8s0 master team0

      These commands create profiles for enp7s0 and enp8s0, and add them to the team0 connection.

    2. To assign an existing connection profile to the team:

      1. Set the master parameter of these connections to team0:

        # nmcli connection modify bond0 master team0
        # nmcli connection modify bond1 master team0

        These commands assign the existing connection profiles named bond0 and bond1 to the team0 connection.

      2. Reactivate the connections:

        # nmcli connection up bond0
        # nmcli connection up bond1
  5. Configure the IPv4 settings:

    • To use this team device as a port of other devices, enter:

      # nmcli connection modify team0 ipv4.method disabled
    • To use DHCP, no action is required.
    • To set a static IPv4 address, network mask, default gateway, and DNS server to the team0 connection, enter:

      # nmcli connection modify team0 ipv4.addresses '192.0.2.1/24' ipv4.gateway '192.0.2.254' ipv4.dns '192.0.2.253' ipv4.dns-search 'example.com' ipv4.method manual
  6. Configure the IPv6 settings:

    • To use this team device as a port of other devices, enter:

      # nmcli connection modify team0 ipv6.method disabled
    • To use DHCP, no action is required.
    • To set a static IPv6 address, network mask, default gateway, and DNS server to the team0 connection, enter:

      # nmcli connection modify team0 ipv6.addresses '2001:db8:1::1/64' ipv6.gateway '2001:db8:1::fffe' ipv6.dns '2001:db8:1::fffd' ipv6.dns-search 'example.com' ipv6.method manual
  7. Activate the connection:

    # nmcli connection up team0

Verification

  • Display the status of the team:

    # teamdctl team0 state
    setup:
      runner: activebackup
    ports:
      enp7s0
        link watches:
          link summary: up
          instance[link_watch_0]:
            name: ethtool
            link: up
            down count: 0
      enp8s0
        link watches:
          link summary: up
          instance[link_watch_0]:
            name: ethtool
            link: up
            down count: 0
    runner:
      active port: enp7s0

    In this example, both ports are up.

4.5. Configuring a network team by using the RHEL web console

Use the RHEL web console to configure a network team if you prefer to manage network settings using a web browser-based interface.

Important

Network teaming is deprecated in Red Hat Enterprise Linux 9. Consider using the network bonding driver as an alternative. For details, see Configuring network bonding.

Prerequisites

Procedure

  1. Select the Networking tab in the navigation on the left side of the screen.
  2. Click Add team in the Interfaces section.
  3. Enter the name of the team device you want to create.
  4. Select the interfaces that should be ports of the team.
  5. Select the runner of the team.

    If you select Load balancing or 802.3ad LACP, the web console shows the additional field Balancer.

  6. Set the link watcher:

    • If you select Ethtool, additionally, set a link up and link down delay.
    • If you set ARP ping or NSNA ping, additionally, set a ping interval and ping target.
    team settings
  7. Click Apply.
  8. By default, the team uses a dynamic IP address. If you want to set a static IP address:

    1. Click the name of the team in the Interfaces section.
    2. Click Edit next to the protocol you want to configure.
    3. Select Manual next to Addresses, and enter the IP address, prefix, and default gateway.
    4. In the DNS section, click the + button, and enter the IP address of the DNS server. Repeat this step to set multiple DNS servers.
    5. In the DNS search domains section, click the + button, and enter the search domain.
    6. If the interface requires static routes, configure them in the Routes section.

      bond team bridge vlan.ipv4
    7. Click Apply

Verification

  1. Select the Networking tab in the navigation on the left side of the screen, and check if there is incoming and outgoing traffic on the interface.

    team verify
  2. Display the status of the team:

    # teamdctl team0 state
    setup:
      runner: activebackup
    ports:
      enp7s0
        link watches:
          link summary: up
          instance[link_watch_0]:
            name: ethtool
            link: up
            down count: 0
      enp8s0
        link watches:
          link summary: up
          instance[link_watch_0]:
            name: ethtool
            link: up
            down count: 0
    runner:
      active port: enp7s0

    In this example, both ports are up.

Additional resources

4.6. Configuring a network team by using nm-connection-editor

If you use Red Hat Enterprise Linux with a graphical interface, you can configure network teams using the nm-connection-editor application.

Note that nm-connection-editor can add only new ports to a team. To use an existing connection profile as a port, create the team using the nmcli utility as described in Configuring a network team by using nmcli.

Important

Network teaming is deprecated in Red Hat Enterprise Linux 9. Consider using the network bonding driver as an alternative. For details, see Configuring network bonding.

Prerequisites

  • The teamd and NetworkManager-team packages are installed.
  • Two or more physical or virtual network devices are installed on the server.
  • To use Ethernet devices as ports of the team, the physical or virtual Ethernet devices must be installed on the server.
  • To use team, bond, or VLAN devices as ports of the team, ensure that these devices are not already configured.

Procedure

  1. Open a terminal, and enter nm-connection-editor:

    $ nm-connection-editor
  2. Click the + button to add a new connection.
  3. Select the Team connection type, and click Create.
  4. On the Team tab:

    1. Optional: Set the name of the team interface in the Interface name field.
    2. Click the Add button to add a new connection profile for a network interface and adding the profile as a port to the team.

      1. Select the connection type of the interface. For example, select Ethernet for a wired connection.
      2. Optional: Set a connection name for the port.
      3. If you create a connection profile for an Ethernet device, open the Ethernet tab, and select in the Device field the network interface you want to add as a port to the team. If you selected a different device type, configure it accordingly. Note that you can only use Ethernet interfaces in a team that are not assigned to any connection.
      4. Click Save.
    3. Repeat the previous step for each interface you want to add to the team.

      add nic to team in nm connection editor

    4. Click the Advanced button to set advanced options to the team connection.

      1. On the Runner tab, select the runner.
      2. On the Link Watcher tab, set the link watcher and its optional settings.
      3. Click OK.
  5. Configure the IP address settings on both the IPv4 Settings and IPv6 Settings tabs:

    • To use this bridge device as a port of other devices, set the Method field to Disabled.
    • To use DHCP, leave the Method field at its default, Automatic (DHCP).
    • To use static IP settings, set the Method field to Manual and fill the fields accordingly:

      team IP settings nm connection editor

  6. Click Save.
  7. Close nm-connection-editor.

Verification

  • Display the status of the team:

    # teamdctl team0 state
    setup:
      runner: activebackup
    ports:
      enp7s0
        link watches:
          link summary: up
          instance[link_watch_0]:
            name: ethtool
            link: up
            down count: 0
      enp8s0
        link watches:
          link summary: up
          instance[link_watch_0]:
            name: ethtool
            link: up
            down count: 0
    runner:
      active port: enp7s0

Chapter 5. Configuring VLAN tagging

A Virtual Local Area Network (VLAN) is a logical network within a physical network. The VLAN interface tags packets with the VLAN ID as they pass through the interface, and removes tags of returning packets. You create VLAN interfaces on top of another interface, such as Ethernet, bond, team, or bridge devices. These interfaces are called the parent interface.

Red Hat Enterprise Linux provides administrators different options to configure VLAN devices. For example:

  • Use nmcli to configure VLAN tagging using the command line.
  • Use the RHEL web console to configure VLAN tagging using a web browser.
  • Use nmtui to configure VLAN tagging in a text-based user interface.
  • Use the nm-connection-editor application to configure connections in a graphical interface.
  • Use nmstatectl to configure connections through the Nmstate API.
  • Use RHEL System Roles to automate the VLAN configuration on one or multiple hosts.

5.1. Configuring VLAN tagging by using nmcli

You can configure Virtual Local Area Network (VLAN) tagging on the command line using the nmcli utility.

Prerequisites

  • The interface you plan to use as a parent to the virtual VLAN interface supports VLAN tags.
  • If you configure the VLAN on top of a bond interface:

    • The ports of the bond are up.
    • The bond is not configured with the fail_over_mac=follow option. A VLAN virtual device cannot change its MAC address to match the parent’s new MAC address. In such a case, the traffic would still be sent with the incorrect source MAC address.
    • The bond is usually not expected to get IP addresses from a DHCP server or IPv6 auto-configuration. Ensure it by setting the ipv4.method=disable and ipv6.method=ignore options while creating the bond. Otherwise, if DHCP or IPv6 auto-configuration fails after some time, the interface might be brought down.
  • The switch, the host is connected to, is configured to support VLAN tags. For details, see the documentation of your switch.

Procedure

  1. Display the network interfaces:

    # nmcli device status
    DEVICE   TYPE      STATE         CONNECTION
    enp1s0   ethernet  disconnected  enp1s0
    bridge0  bridge    connected     bridge0
    bond0    bond      connected     bond0
    ...
  2. Create the VLAN interface. For example, to create a VLAN interface named vlan10 that uses enp1s0 as its parent interface and that tags packets with VLAN ID 10, enter:

    # nmcli connection add type vlan con-name vlan10 ifname vlan10 vlan.parent enp1s0 vlan.id 10

    Note that the VLAN must be within the range from 0 to 4094.

  3. By default, the VLAN connection inherits the maximum transmission unit (MTU) from the parent interface. Optionally, set a different MTU value:

    # nmcli connection modify vlan10 ethernet.mtu 2000
  4. Configure the IPv4 settings:

    • To use this VLAN device as a port of other devices, enter:

      # nmcli connection modify vlan10 ipv4.method disabled
    • To use DHCP, no action is required.
    • To set a static IPv4 address, network mask, default gateway, and DNS server to the vlan10 connection, enter:

      # nmcli connection modify vlan10 ipv4.addresses '192.0.2.1/24' ipv4.gateway '192.0.2.254' ipv4.dns '192.0.2.253' ipv4.method manual
  5. Configure the IPv6 settings:

    • To use this VLAN device as a port of other devices, enter:

      # nmcli connection modify vlan10 ipv6.method disabled
    • To use DHCP, no action is required.
    • To set a static IPv6 address, network mask, default gateway, and DNS server to the vlan10 connection, enter:

      # nmcli connection modify vlan10 ipv6.addresses '2001:db8:1::1/32' ipv6.gateway '2001:db8:1::fffe' ipv6.dns '2001:db8:1::fffd' ipv6.method manual
  6. Activate the connection:

    # nmcli connection up vlan10

Verification

  • Verify the settings:

    # ip -d addr show vlan10
    4: vlan10@enp1s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP group default qlen 1000
        link/ether 52:54:00:72:2f:6e brd ff:ff:ff:ff:ff:ff promiscuity 0
        vlan protocol 802.1Q id 10 <REORDER_HDR> numtxqueues 1 numrxqueues 1 gso_max_size 65536 gso_max_segs 65535
        inet 192.0.2.1/24 brd 192.0.2.255 scope global noprefixroute vlan10
           valid_lft forever preferred_lft forever
        inet6 2001:db8:1::1/32 scope global noprefixroute
           valid_lft forever preferred_lft forever
        inet6 fe80::8dd7:9030:6f8e:89e6/64 scope link noprefixroute
           valid_lft forever preferred_lft forever

5.2. Configuring nested VLANs using nmcli commands

802.1ad is a protocol used for Virtual Local Area Network (VLAN) tagging. It is also known as Q-in-Q tagging. You can use this technology to create multiple VLAN tags within a single Ethernet frame to achieve the following benefits:

  • Increased network scalability by creating multiple isolated network segments within a VLAN. This enables you to segment and organize large networks into smaller, manageable units.
  • Improved traffic management by isolating and controlling different types of network traffic. This can improve the network performance and reduce network congestion.
  • Efficient resource utilization by enabling the creation of smaller, more targeted network segments.
  • Enhanced security by isolating network traffic and reducing the risk of unauthorized access to sensitive data.

Prerequisites

  • The interface you plan to use as a parent to the virtual VLAN interface supports VLAN tags.
  • If you configure the VLAN on top of a bond interface:

    • The ports of the bond are up.
    • The bond is not configured with the fail_over_mac=follow option. A VLAN virtual device cannot change its MAC address to match the parent’s new MAC address. In such a case, the traffic would still be sent with the incorrect source MAC address.
    • The bond is usually not expected to get IP addresses from a DHCP server or IPv6 auto-configuration. Ensure it by setting the ipv4.method=disable and ipv6.method=ignore options while creating the bond. Otherwise, if DHCP or IPv6 auto-configuration fails after some time, the interface might be brought down.
  • The switch, the host is connected to, is configured to support VLAN tags. For details, see the documentation of your switch.

Procedure

  1. Display the physical network devices:

    # nmcli device status
    DEVICE   TYPE      STATE         CONNECTION
    enp1s0  ethernet  connected      enp1s0
    ...
  2. Create the base VLAN interface. For example, to create a base VLAN interface named vlan10 that uses enp1s0 as its parent interface and that tags packets with VLAN ID 10, enter:

    # nmcli connection add type vlan con-name vlan10 dev enp1s0 vlan.id 10

    Note that the VLAN must be within the range from 0 to 4094.

  3. By default, the VLAN connection inherits the maximum transmission unit (MTU) from the parent interface. Optionally, set a different MTU value:

    # nmcli connection modify vlan10 ethernet.mtu 2000
  4. Create the nested VLAN interface on top of the base VLAN interface:

    # nmcli connection add type vlan con-name vlan10.20 dev enp1s0.10 id 20 vlan.protocol 802.1ad

    This command creates a new VLAN connection with a name of vlan10.20 and a VLAN ID of 20 on the parent VLAN connection vlan10. The dev option specifies the parent network device. In this case it is enp1s0.10. The vlan.protocol option specifies the VLAN encapsulation protocol. In this case it is 802.1ad (Q-in-Q).

  5. Configure the IP settings of the nested VLAN interface.

    1. Configure the IPv4 settings of the nested VLAN interface. For example, to set a static IPv4 address, network mask, default gateway, and DNS server, enter:

      # nmcli connection modify vlan10 ipv4.addresses '192.0.2.1/24'
      # nmcli connection modify vlan10 ipv4.gateway '192.0.2.254'
      # nmcli connection modify vlan10 ipv4.dns '192.0.2.253'
      # nmcli connection modify vlan10 ipv4.method manual
    2. Configure the IPv6 settings of the nested VLAN interface. For example, to set a static IPv6 address, network mask, default gateway, and DNS server, enter:

      # nmcli connection modify vlan10 ipv6.addresses '2001:db8:1::1/32'
      # nmcli connection modify vlan10 ipv6.gateway '2001:db8:1::fffe'
      # nmcli connection modify vlan10 ipv6.dns '2001:db8:1::fffd'
      # nmcli connection modify vlan10 ipv6.method manual

Verification

  1. Verify the configuration of the nested VLAN interface:

    # ip -d addr show enp1s0.10.20
    10: enp1s0.10.20@enp1s0.10: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP group default qlen 1000
        link/ether 52:54:00:d2:74:3e brd ff:ff:ff:ff:ff:ff promiscuity 0 minmtu 0 maxmtu 65535
        vlan protocol 802.1ad id 20 <REORDER_HDR> numtxqueues 1 numrxqueues 1 gso_max_size 65536 gso_max_segs 65535 tso_max_size 65536 tso_max_segs 65535 gro_max_size 65536
        inet 192.0.2.1/24 brd 192.0.2.255 scope global noprefixroute enp1s0.10.20
           valid_lft forever preferred_lft forever
        inet6 2001:db8:1::1/32 scope global noprefixroute
           valid_lft forever preferred_lft forever
        inet6 fe80::ce3b:84c5:9ef8:d0e6/64 scope link noprefixroute
           valid_lft forever preferred_lft forever

Additional resources

  • nm-settings(5) man page

5.3. Configuring VLAN tagging by using the RHEL web console

Use the RHEL web console to configure VLAN tagging if you prefer to manage network settings using a web browser-based interface.

Prerequisites

  • The interface you plan to use as a parent to the virtual VLAN interface supports VLAN tags.
  • If you configure the VLAN on top of a bond interface:

    • The ports of the bond are up.
    • The bond is not configured with the fail_over_mac=follow option. A VLAN virtual device cannot change its MAC address to match the parent’s new MAC address. In such a case, the traffic would still be sent with the incorrect source MAC address.
    • The bond is usually not expected to get IP addresses from a DHCP server or IPv6 auto-configuration. Ensure it by disabling the IPv4 and IPv6 protocol creating the bond. Otherwise, if DHCP or IPv6 auto-configuration fails after some time, the interface might be brought down.
  • The switch, the host is connected to, is configured to support VLAN tags. For details, see the documentation of your switch.

Procedure

  1. Select the Networking tab in the navigation on the left side of the screen.
  2. Click Add VLAN in the Interfaces section.
  3. Select the parent device.
  4. Enter the VLAN ID.
  5. Enter the name of the VLAN device or keep the automatically-generated name.

    vlan settings
  6. Click Apply.
  7. By default, the VLAN device uses a dynamic IP address. If you want to set a static IP address:

    1. Click the name of the VLAN device in the Interfaces section.
    2. Click Edit next to the protocol you want to configure.
    3. Select Manual next to Addresses, and enter the IP address, prefix, and default gateway.
    4. In the DNS section, click the + button, and enter the IP address of the DNS server. Repeat this step to set multiple DNS servers.
    5. In the DNS search domains section, click the + button, and enter the search domain.
    6. If the interface requires static routes, configure them in the Routes section.

      bond team bridge vlan.ipv4
    7. Click Apply

Verification

  • Select the Networking tab in the navigation on the left side of the screen, and check if there is incoming and outgoing traffic on the interface:

    vlan verify

5.4. Configuring VLAN tagging by using nmtui

The nmtui application provides a text-based user interface for NetworkManager. You can use nmtui to configure VLAN tagging on a host without a graphical interface.

Note

In nmtui:

  • Navigate by using the cursor keys.
  • Press a button by selecting it and hitting Enter.
  • Select and deselect checkboxes by using Space.

Prerequisites

  • The interface you plan to use as a parent to the virtual VLAN interface supports VLAN tags.
  • If you configure the VLAN on top of a bond interface:

    • The ports of the bond are up.
    • The bond is not configured with the fail_over_mac=follow option. A VLAN virtual device cannot change its MAC address to match the parent’s new MAC address. In such a case, the traffic would still be sent with the then incorrect source MAC address.
    • The bond is usually not expected to get IP addresses from a DHCP server or IPv6 auto-configuration. Ensure it by setting the ipv4.method=disable and ipv6.method=ignore options while creating the bond. Otherwise, if DHCP or IPv6 auto-configuration fails after some time, the interface might be brought down.
  • The switch the host is connected to is configured to support VLAN tags. For details, see the documentation of your switch.

Procedure

  1. If you do not know the network device name on which you want configure VLAN tagging, display the available devices:

    # nmcli device status
    DEVICE     TYPE      STATE                   CONNECTION
    enp1s0     ethernet  unavailable             --
    ...
  2. Start nmtui:

    # nmtui
  3. Select Edit a connection, and press Enter.
  4. Press the Add button.
  5. Select VLAN from the list of network types, and press Enter.
  6. Optional: Enter a name for the NetworkManager profile to be created.

    On hosts with multiple profiles, a meaningful name makes it easier to identify the purpose of a profile.

  7. Enter the VLAN device name to be created into the Device field.
  8. Enter the name of the device on which you want to configure VLAN tagging into the Parent field.
  9. Enter the VLAN ID. The ID must be within the range from 0 to 4094.
  10. Depending on your environment, configure the IP address settings in the IPv4 configuration and IPv6 configuration areas accordingly. For this, press the button next to these areas, and select:

    • Disabled, if this VLAN device does not require an IP address or you want to use it as a port of other devices.
    • Automatic, if a DHCP server or stateless address autoconfiguration (SLAAC) dynamically assigns an IP address to the VLAN device.
    • Manual, if the network requires static IP address settings. In this case, you must fill further fields:

      1. Press the Show button next to the protocol you want to configure to display additional fields.
      2. Press the Add button next to Addresses, and enter the IP address and the subnet mask in Classless Inter-Domain Routing (CIDR) format.

        If you do not specify a subnet mask, NetworkManager sets a /32 subnet mask for IPv4 addresses and /64 for IPv6 addresses.

      3. Enter the address of the default gateway.
      4. Press the Add button next to DNS servers, and enter the DNS server address.
      5. Press the Add button next to Search domains, and enter the DNS search domain.

    Figure 5.1. Example of a VLAN connection with static IP address settings

    nmtui vlan static IP
  11. Press the OK button to create and automatically activate the new connection.
  12. Press the Back button to return to the main menu.
  13. Select Quit, and press Enter to close the nmtui application.

Verification

  • Verify the settings:

    # ip -d addr show vlan10
    4: vlan10@enp1s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP group default qlen 1000
        link/ether 52:54:00:72:2f:6e brd ff:ff:ff:ff:ff:ff promiscuity 0
        vlan protocol 802.1Q id 10 <REORDER_HDR> numtxqueues 1 numrxqueues 1 gso_max_size 65536 gso_max_segs 65535
        inet 192.0.2.1/24 brd 192.0.2.255 scope global noprefixroute vlan10
           valid_lft forever preferred_lft forever
        inet6 2001:db8:1::1/32 scope global noprefixroute
           valid_lft forever preferred_lft forever
        inet6 fe80::8dd7:9030:6f8e:89e6/64 scope link noprefixroute
           valid_lft forever preferred_lft forever

5.5. Configuring VLAN tagging by using nm-connection-editor

You can configure Virtual Local Area Network (VLAN) tagging in a graphical interface using the nm-connection-editor application.

Prerequisites

  • The interface you plan to use as a parent to the virtual VLAN interface supports VLAN tags.
  • If you configure the VLAN on top of a bond interface:

    • The ports of the bond are up.
    • The bond is not configured with the fail_over_mac=follow option. A VLAN virtual device cannot change its MAC address to match the parent’s new MAC address. In such a case, the traffic would still be sent with the incorrect source MAC address.
  • The switch, the host is connected, to is configured to support VLAN tags. For details, see the documentation of your switch.

Procedure

  1. Open a terminal, and enter nm-connection-editor:

    $ nm-connection-editor
  2. Click the + button to add a new connection.
  3. Select the VLAN connection type, and click Create.
  4. On the VLAN tab:

    1. Select the parent interface.
    2. Select the VLAN id. Note that the VLAN must be within the range from 0 to 4094.
    3. By default, the VLAN connection inherits the maximum transmission unit (MTU) from the parent interface. Optionally, set a different MTU value.
    4. Optionally, set the name of the VLAN interface and further VLAN-specific options.

      vlan settings nm connection editor

  5. Configure the IP address settings on both the IPv4 Settings and IPv6 Settings tabs:

    • To use this bridge device as a port of other devices, set the Method field to Disabled.
    • To use DHCP, leave the Method field at its default, Automatic (DHCP).
    • To use static IP settings, set the Method field to Manual and fill the fields accordingly:

      vlan IP settings nm connection editor

  6. Click Save.
  7. Close nm-connection-editor.

Verification

  1. Verify the settings:

    # ip -d addr show vlan10
    4: vlan10@enp1s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP group default qlen 1000
        link/ether 52:54:00:d5:e0:fb brd ff:ff:ff:ff:ff:ff promiscuity 0
        vlan protocol 802.1Q id 10 <REORDER_HDR> numtxqueues 1 numrxqueues 1 gso_max_size 65536 gso_max_segs 65535
        inet 192.0.2.1/24 brd 192.0.2.255 scope global noprefixroute vlan10
           valid_lft forever preferred_lft forever
        inet6 2001:db8:1::1/32 scope global noprefixroute
           valid_lft forever preferred_lft forever
        inet6 fe80::8dd7:9030:6f8e:89e6/64 scope link noprefixroute
           valid_lft forever preferred_lft forever

5.6. Configuring VLAN tagging by using nmstatectl

Use the nmstatectl utility to configure Virtual Local Area Network VLAN through the Nmstate API. The Nmstate API ensures that, after setting the configuration, the result matches the configuration file. If anything fails, nmstatectl automatically rolls back the changes to avoid leaving the system in an incorrect state.

Depending on your environment, adjust the YAML file accordingly. For example, to use different devices than Ethernet adapters in the VLAN, adapt the base-iface attribute and type attributes of the ports you use in the VLAN.

Prerequisites

  • To use Ethernet devices as ports in the VLAN, the physical or virtual Ethernet devices must be installed on the server.
  • The nmstate package is installed.

Procedure

  1. Create a YAML file, for example ~/create-vlan.yml, with the following content:

    ---
    interfaces:
    - name: vlan10
      type: vlan
      state: up
      ipv4:
        enabled: true
        address:
        - ip: 192.0.2.1
          prefix-length: 24
        dhcp: false
      ipv6:
        enabled: true
        address:
        - ip: 2001:db8:1::1
          prefix-length: 64
        autoconf: false
        dhcp: false
      vlan:
        base-iface: enp1s0
        id: 10
    - name: enp1s0
      type: ethernet
      state: up
    
    routes:
      config:
      - destination: 0.0.0.0/0
        next-hop-address: 192.0.2.254
        next-hop-interface: vlan10
      - destination: ::/0
        next-hop-address: 2001:db8:1::fffe
        next-hop-interface: vlan10
    
    dns-resolver:
      config:
        search:
        - example.com
        server:
        - 192.0.2.200
        - 2001:db8:1::ffbb

    These settings define a VLAN with ID 10 that uses the enp1s0 device. As the child device, the VLAN connection has the following settings:

    • A static IPv4 address - 192.0.2.1 with the /24 subnet mask
    • A static IPv6 address - 2001:db8:1::1 with the /64 subnet mask
    • An IPv4 default gateway - 192.0.2.254
    • An IPv6 default gateway - 2001:db8:1::fffe
    • An IPv4 DNS server - 192.0.2.200
    • An IPv6 DNS server - 2001:db8:1::ffbb
    • A DNS search domain - example.com
  2. Apply the settings to the system:

    # nmstatectl apply ~/create-vlan.yml

Verification

  1. Display the status of the devices and connections:

    # nmcli device status
    DEVICE      TYPE      STATE      CONNECTION
    vlan10      vlan      connected  vlan10
  2. Display all settings of the connection profile:

    # nmcli connection show vlan10
    connection.id:              vlan10
    connection.uuid:            1722970f-788e-4f81-bd7d-a86bf21c9df5
    connection.stable-id:       --
    connection.type:            vlan
    connection.interface-name:  vlan10
    ...
  3. Display the connection settings in YAML format:

    # nmstatectl show vlan0

Additional resources

  • nmstatectl(8) man page
  • /usr/share/doc/nmstate/examples/ directory

5.7. Configuring VLAN tagging by using the network RHEL System Role

You can use the network RHEL System Role to configure VLAN tagging. This example adds an Ethernet connection and a VLAN with ID 10 on top of this Ethernet connection. As the child device, the VLAN connection contains the IP, default gateway, and DNS configurations.

Depending on your environment, adjust the play accordingly. For example:

  • To use the VLAN as a port in other connections, such as a bond, omit the ip attribute, and set the IP configuration in the child configuration.
  • To use team, bridge, or bond devices in the VLAN, adapt the interface_name and type attributes of the ports you use in the VLAN.

Perform this procedure on the Ansible control node.

Prerequisites

  • You have prepared the control node and the managed nodes
  • You are logged in to the control node as a user who can run playbooks on the managed nodes.
  • The account you use to connect to the managed nodes has sudo permissions on them.
  • The managed nodes or groups of managed nodes on which you want to run this playbook are listed in the Ansible inventory file.

Procedure

  1. Create a playbook file, for example ~/vlan-ethernet.yml, with the following content:

    ---
    - name: Configure the network
      hosts: managed-node-01.example.com
      tasks:
      - name: Configure a VLAN that uses an Ethernet connection
        include_role:
          name: rhel-system-roles.network
    
        vars:
          network_connections:
            # Add an Ethernet profile for the underlying device of the VLAN
            - name: enp1s0
              type: ethernet
              interface_name: enp1s0
              autoconnect: yes
              state: up
              ip:
                dhcp4: no
                auto6: no
    
            # Define the VLAN profile
            - name: enp1s0.10
              type: vlan
              ip:
                address:
                  - "192.0.2.1/24"
                  - "2001:db8:1::1/64"
                gateway4: 192.0.2.254
                gateway6: 2001:db8:1::fffe
                dns:
                  - 192.0.2.200
                  - 2001:db8:1::ffbb
                dns_search:
                  - example.com
              vlan_id: 10
              parent: enp1s0
              state: up

    These settings define a VLAN to operate on top of the enp1s0 device. The VLAN interface has the following settings:

    • A static IPv4 address - 192.0.2.1 with a /24 subnet mask
    • A static IPv6 address - 2001:db8:1::1 with a /64 subnet mask
    • An IPv4 default gateway - 192.0.2.254
    • An IPv6 default gateway - 2001:db8:1::fffe
    • An IPv4 DNS server - 192.0.2.200
    • An IPv6 DNS server - 2001:db8:1::ffbb
    • A DNS search domain - example.com
    • VLAN ID - 10

    The parent attribute in the VLAN profile configures the VLAN to operate on top of the enp1s0 device. As the child device, the VLAN connection contains the IP, default gateway, and DNS configurations.

  2. Validate the playbook syntax:

    # ansible-playbook ~/vlan-ethernet.yml --syntax-check

    Note that this command only validates the syntax and does not protect against a wrong but valid configuration.

  3. Run the playbook:

    # ansible-playbook ~/vlan-ethernet.yml

Additional resources

  • /usr/share/ansible/roles/rhel-system-roles.network/README.md file

5.8. Additional resources

Chapter 6. Configuring a network bridge

A network bridge is a link-layer device which forwards traffic between networks based on a table of MAC addresses. The bridge builds the MAC addresses table by listening to network traffic and thereby learning what hosts are connected to each network. For example, you can use a software bridge on a Red Hat Enterprise Linux host to emulate a hardware bridge or in virtualization environments, to integrate virtual machines (VM) to the same network as the host.

A bridge requires a network device in each network the bridge should connect. When you configure a bridge, the bridge is called controller and the devices it uses ports.

You can create bridges on different types of devices, such as:

  • Physical and virtual Ethernet devices
  • Network bonds
  • Network teams
  • VLAN devices

Due to the IEEE 802.11 standard which specifies the use of 3-address frames in Wi-Fi for the efficient use of airtime, you cannot configure a bridge over Wi-Fi networks operating in Ad-Hoc or Infrastructure modes.

6.1. Configuring a network bridge by using nmcli

To configure a network bridge on the command line, use the nmcli utility.

Prerequisites

Procedure

  1. Create a bridge interface:

    # nmcli connection add type bridge con-name bridge0 ifname bridge0

    This command creates a bridge named bridge0, enter:

  2. Display the network interfaces, and note the names of the interfaces you want to add to the bridge:

    # nmcli device status
    DEVICE  TYPE      STATE         CONNECTION
    enp7s0  ethernet  disconnected  --
    enp8s0  ethernet  disconnected  --
    bond0   bond      connected     bond0
    bond1   bond      connected     bond1
    ...

    In this example:

    • enp7s0 and enp8s0 are not configured. To use these devices as ports, add connection profiles in the next step.
    • bond0 and bond1 have existing connection profiles. To use these devices as ports, modify their profiles in the next step.
  3. Assign the interfaces to the bridge.

    1. If the interfaces you want to assign to the bridge are not configured, create new connection profiles for them:

      # nmcli connection add type ethernet slave-type bridge con-name bridge0-port1 ifname enp7s0 master bridge0
      # nmcli connection add type ethernet slave-type bridge con-name bridge0-port2 ifname enp8s0 master bridge0

      These commands create profiles for enp7s0 and enp8s0, and add them to the bridge0 connection.

    2. If you want to assign an existing connection profile to the bridge:

      1. Set the master parameter of these connections to bridge0:

        # nmcli connection modify bond0 master bridge0
        # nmcli connection modify bond1 master bridge0

        These commands assign the existing connection profiles named bond0 and bond1 to the bridge0 connection.

      2. Reactivate the connections:

        # nmcli connection up bond0
        # nmcli connection up bond1
  4. Configure the IPv4 settings:

    • To use this bridge device as a port of other devices, enter:

      # nmcli connection modify bridge0 ipv4.method disabled
    • To use DHCP, no action is required.
    • To set a static IPv4 address, network mask, default gateway, and DNS server to the bridge0 connection, enter:

      # nmcli connection modify bridge0 ipv4.addresses '192.0.2.1/24' ipv4.gateway '192.0.2.254' ipv4.dns '192.0.2.253' ipv4.dns-search 'example.com' ipv4.method manual
  5. Configure the IPv6 settings:

    • To use this bridge device as a port of other devices, enter:

      # nmcli connection modify bridge0 ipv6.method disabled
    • To use DHCP, no action is required.
    • To set a static IPv6 address, network mask, default gateway, and DNS server to the bridge0 connection, enter:

      # nmcli connection modify bridge0 ipv6.addresses '2001:db8:1::1/64' ipv6.gateway '2001:db8:1::fffe' ipv6.dns '2001:db8:1::fffd' ipv6.dns-search 'example.com' ipv6.method manual
  6. Optional: Configure further properties of the bridge. For example, to set the Spanning Tree Protocol (STP) priority of bridge0 to 16384, enter:

    # nmcli connection modify bridge0 bridge.priority '16384'

    By default, STP is enabled.

  7. Activate the connection:

    # nmcli connection up bridge0
  8. Verify that the ports are connected, and the CONNECTION column displays the port’s connection name:

    # nmcli device
    DEVICE   TYPE      STATE      CONNECTION
    ...
    enp7s0   ethernet  connected  bridge0-port1
    enp8s0   ethernet  connected  bridge0-port2

    When you activate any port of the connection, NetworkManager also activates the bridge, but not the other ports of it. You can configure that Red Hat Enterprise Linux enables all ports automatically when the bridge is enabled:

    1. Enable the connection.autoconnect-slaves parameter of the bridge connection:

      # nmcli connection modify bridge0 connection.autoconnect-slaves 1
    2. Reactivate the bridge:

      # nmcli connection up bridge0

Verification

  • Use the ip utility to display the link status of Ethernet devices that are ports of a specific bridge:

    # ip link show master bridge0
    3: enp7s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel master bridge0 state UP mode DEFAULT group default qlen 1000
        link/ether 52:54:00:62:61:0e brd ff:ff:ff:ff:ff:ff
    4: enp8s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel master bridge0 state UP mode DEFAULT group default qlen 1000
        link/ether 52:54:00:9e:f1:ce brd ff:ff:ff:ff:ff:ff
  • Use the bridge utility to display the status of Ethernet devices that are ports of any bridge device:

    # bridge link show
    3: enp7s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 master bridge0 state forwarding priority 32 cost 100
    4: enp8s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 master bridge0 state listening priority 32 cost 100
    5: enp9s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 master bridge1 state forwarding priority 32 cost 100
    6: enp11s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 master bridge1 state blocking priority 32 cost 100
    ...

    To display the status for a specific Ethernet device, use the bridge link show dev ethernet_device_name command.

6.2. Configuring a network bridge by using the RHEL web console

Use the RHEL web console to configure a network bridge if you prefer to manage network settings using a web browser-based interface.

Prerequisites

Procedure

  1. Select the Networking tab in the navigation on the left side of the screen.
  2. Click Add bridge in the Interfaces section.
  3. Enter the name of the bridge device you want to create.
  4. Select the interfaces that should be ports of the bridge.
  5. Optional: Enable the Spanning tree protocol (STP) feature to avoid bridge loops and broadcast radiation.

    bridge settings
  6. Click Apply.
  7. By default, the bridge uses a dynamic IP address. If you want to set a static IP address:

    1. Click the name of the bridge in the Interfaces section.
    2. Click Edit next to the protocol you want to configure.
    3. Select Manual next to Addresses, and enter the IP address, prefix, and default gateway.
    4. In the DNS section, click the + button, and enter the IP address of the DNS server. Repeat this step to set multiple DNS servers.
    5. In the DNS search domains section, click the + button, and enter the search domain.
    6. If the interface requires static routes, configure them in the Routes section.

      bond team bridge vlan.ipv4
    7. Click Apply

Verification

  1. Select the Networking tab in the navigation on the left side of the screen, and check if there is incoming and outgoing traffic on the interface:

    bridge verify

6.3. Configuring a network bridge by using nmtui

The nmtui application provides a text-based user interface for NetworkManager. You can use nmtui to configure a network bridge on a host without a graphical interface.

Note

In nmtui:

  • Navigate by using the cursor keys.
  • Press a button by selecting it and hitting Enter.
  • Select and deselect checkboxes by using Space.

Prerequisites

  • Two or more physical or virtual network devices are installed on the server.
  • To use Ethernet devices as ports of the bridge, the physical or virtual Ethernet devices must be installed on the server.

Procedure

  1. If you do not know the network device names on which you want configure a network bridge, display the available devices:

    # nmcli device status
    DEVICE     TYPE      STATE                   CONNECTION
    enp7s0     ethernet  unavailable             --
    enp8s0     ethernet  unavailable             --
    ...
  2. Start nmtui:

    # nmtui
  3. Select Edit a connection, and press Enter.
  4. Press the Add button.
  5. Select Bridge from the list of network types, and press Enter.
  6. Optional: Enter a name for the NetworkManager profile to be created.

    On hosts with multiple profiles, a meaningful name makes it easier to identify the purpose of a profile.

  7. Enter the bridge device name to be created into the Device field.
  8. Add ports to the bridge to be created:

    1. Press the Add button next to the Slaves list.
    2. Select the type of the interface you want to add as port to the bridge, for example, Ethernet.
    3. Optional: Enter a name for the NetworkManager profile to be created for this bridge port.
    4. Enter the port’s device name into the Device field.
    5. Press the OK button to return to the window with the bridge settings.

      Figure 6.1. Adding an Ethernet device as port to a bridge

      nmtui bridge add port
    6. Repeat these steps to add more ports to the bridge.
  9. Depending on your environment, configure the IP address settings in the IPv4 configuration and IPv6 configuration areas accordingly. For this, press the button next to these areas, and select:

    • Disabled, if the bridge does not require an IP address.
    • Automatic, if a DHCP server or stateless address autoconfiguration (SLAAC) dynamically assigns an IP address to the bridge.
    • Manual, if the network requires static IP address settings. In this case, you must fill further fields:

      1. Press the Show button next to the protocol you want to configure to display additional fields.
      2. Press the Add button next to Addresses, and enter the IP address and the subnet mask in Classless Inter-Domain Routing (CIDR) format.

        If you do not specify a subnet mask, NetworkManager sets a /32 subnet mask for IPv4 addresses and /64 for IPv6 addresses.

      3. Enter the address of the default gateway.
      4. Press the Add button next to DNS servers, and enter the DNS server address.
      5. Press the Add button next to Search domains, and enter the DNS search domain.

    Figure 6.2. Example of a bridge connection without IP address settings

    nmtui bridge no IP
  10. Press the OK button to create and automatically activate the new connection.
  11. Press the Back button to return to the main menu.
  12. Select Quit, and press Enter to close the nmtui application.

Verification

  1. Use the ip utility to display the link status of Ethernet devices that are ports of a specific bridge:

    # ip link show master bridge0
    3: enp7s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel master bridge0 state UP mode DEFAULT group default qlen 1000
        link/ether 52:54:00:62:61:0e brd ff:ff:ff:ff:ff:ff
    4: enp8s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel master bridge0 state UP mode DEFAULT group default qlen 1000
        link/ether 52:54:00:9e:f1:ce brd ff:ff:ff:ff:ff:ff
  2. Use the bridge utility to display the status of Ethernet devices that are ports of any bridge device:

    # bridge link show
    3: enp7s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 master bridge0 state forwarding priority 32 cost 100
    4: enp8s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 master bridge0 state listening priority 32 cost 100
    ...

    To display the status for a specific Ethernet device, use the bridge link show dev ethernet_device_name command.

6.4. Configuring a network bridge by using nm-connection-editor

If you use Red Hat Enterprise Linux with a graphical interface, you can configure network bridges using the nm-connection-editor application.

Note that nm-connection-editor can add only new ports to a bridge. To use an existing connection profile as a port, create the bridge using the nmcli utility as described in Configuring a network bridge by using nmcli.

Prerequisites

  • Two or more physical or virtual network devices are installed on the server.
  • To use Ethernet devices as ports of the bridge, the physical or virtual Ethernet devices must be installed on the server.
  • To use team, bond, or VLAN devices as ports of the bridge, ensure that these devices are not already configured.

Procedure

  1. Open a terminal, and enter nm-connection-editor:

    $ nm-connection-editor
  2. Click the + button to add a new connection.
  3. Select the Bridge connection type, and click Create.
  4. On the Bridge tab:

    1. Optional: Set the name of the bridge interface in the Interface name field.
    2. Click the Add button to create a new connection profile for a network interface and adding the profile as a port to the bridge.

      1. Select the connection type of the interface. For example, select Ethernet for a wired connection.
      2. Optionally, set a connection name for the port device.
      3. If you create a connection profile for an Ethernet device, open the Ethernet tab, and select in the Device field the network interface you want to add as a port to the bridge. If you selected a different device type, configure it accordingly.
      4. Click Save.
    3. Repeat the previous step for each interface you want to add to the bridge.

      add nic to bridge in nm connection editor

  5. Optional: Configure further bridge settings, such as Spanning Tree Protocol (STP) options.
  6. Configure the IP address settings on both the IPv4 Settings and IPv6 Settings tabs:

    • To use this bridge device as a port of other devices, set the Method field to Disabled.
    • To use DHCP, leave the Method field at its default, Automatic (DHCP).
    • To use static IP settings, set the Method field to Manual and fill the fields accordingly:

      bridge IP settings nm connection editor

  7. Click Save.
  8. Close nm-connection-editor.

Verification

  • Use the ip utility to display the link status of Ethernet devices that are ports of a specific bridge.

    # ip link show master bridge0
    3: enp7s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel master bridge0 state UP mode DEFAULT group default qlen 1000
        link/ether 52:54:00:62:61:0e brd ff:ff:ff:ff:ff:ff
    4: enp8s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel master bridge0 state UP mode DEFAULT group default qlen 1000
        link/ether 52:54:00:9e:f1:ce brd ff:ff:ff:ff:ff:ff
  • Use the bridge utility to display the status of Ethernet devices that are ports in any bridge device:

    # bridge link show
    3: enp7s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 master bridge0 state forwarding priority 32 cost 100
    4: enp8s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 master bridge0 state listening priority 32 cost 100
    5: enp9s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 master bridge1 state forwarding priority 32 cost 100
    6: enp11s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 master bridge1 state blocking priority 32 cost 100
    ...

    To display the status for a specific Ethernet device, use the bridge link show dev ethernet_device_name command.

6.5. Configuring a network bridge by using nmstatectl

Use the nmstatectl utility to configure a network bridge through the Nmstate API. The Nmstate API ensures that, after setting the configuration, the result matches the configuration file. If anything fails, nmstatectl automatically rolls back the changes to avoid leaving the system in an incorrect state.

Depending on your environment, adjust the YAML file accordingly. For example, to use different devices than Ethernet adapters in the bridge, adapt the base-iface attribute and type attributes of the ports you use in the bridge.

Prerequisites

  • Two or more physical or virtual network devices are installed on the server.
  • To use Ethernet devices as ports in the bridge, the physical or virtual Ethernet devices must be installed on the server.
  • To use team, bond, or VLAN devices as ports in the bridge, set the interface name in the port list, and define the corresponding interfaces.
  • The nmstate package is installed.

Procedure

  1. Create a YAML file, for example ~/create-bridge.yml, with the following content:

    ---
    interfaces:
    - name: bridge0
      type: linux-bridge
      state: up
      ipv4:
        enabled: true
        address:
        - ip: 192.0.2.1
          prefix-length: 24
        dhcp: false
      ipv6:
        enabled: true
        address:
        - ip: 2001:db8:1::1
          prefix-length: 64
        autoconf: false
        dhcp: false
      bridge:
        options:
          stp:
            enabled: true
        port:
          - name: enp1s0
          - name: enp7s0
    - name: enp1s0
      type: ethernet
      state: up
    - name: enp7s0
      type: ethernet
      state: up
    
    routes:
      config:
      - destination: 0.0.0.0/0
        next-hop-address: 192.0.2.254
        next-hop-interface: bridge0
      - destination: ::/0
        next-hop-address: 2001:db8:1::fffe
        next-hop-interface: bridge0
    dns-resolver:
      config:
        search:
        - example.com
        server:
        - 192.0.2.200
        - 2001:db8:1::ffbb

    These settings define a network bridge with the following settings:

    • Network interfaces in the bridge: enp1s0 and enp7s0
    • Spanning Tree Protocol (STP): Enabled
    • Static IPv4 address: 192.0.2.1 with the /24 subnet mask
    • Static IPv6 address: 2001:db8:1::1 with the /64 subnet mask
    • IPv4 default gateway: 192.0.2.254
    • IPv6 default gateway: 2001:db8:1::fffe
    • IPv4 DNS server: 192.0.2.200
    • IPv6 DNS server: 2001:db8:1::ffbb
    • DNS search domain: example.com
  2. Apply the settings to the system:

    # nmstatectl apply ~/create-bridge.yml

Verification

  1. Display the status of the devices and connections:

    # nmcli device status
    DEVICE      TYPE      STATE      CONNECTION
    bridge0     bridge    connected  bridge0
  2. Display all settings of the connection profile:

    # nmcli connection show bridge0
    connection.id:              bridge0
    connection.uuid:            e2cc9206-75a2-4622-89cf-1252926060a9
    connection.stable-id:       --
    connection.type:            bridge
    connection.interface-name:  bridge0
    ...
  3. Display the connection settings in YAML format:

    # nmstatectl show bridge0

Additional resources

6.6. Configuring a network bridge by using the network RHEL System Role

You can remotely configure a network bridge by using the network RHEL System Role.

Perform this procedure on the Ansible control node.

Prerequisites

  • You have prepared the control node and the managed nodes
  • You are logged in to the control node as a user who can run playbooks on the managed nodes.
  • The account you use to connect to the managed nodes has sudo permissions on them.
  • The managed nodes or groups of managed nodes on which you want to run this playbook are listed in the Ansible inventory file.
  • Two or more physical or virtual network devices are installed on the server.

Procedure

  1. Create a playbook file, for example ~/bridge-ethernet.yml, with the following content:

    ---
    - name: Configure the network
      hosts: managed-node-01.example.com
      tasks:
      - name: Configure a network bridge that uses two Ethernet ports
        include_role:
          name: rhel-system-roles.network
    
        vars:
          network_connections:
            # Define the bridge profile
            - name: bridge0
              type: bridge
              interface_name: bridge0
              ip:
                address:
                  - "192.0.2.1/24"
                  - "2001:db8:1::1/64"
                gateway4: 192.0.2.254
                gateway6: 2001:db8:1::fffe
                dns:
                  - 192.0.2.200
                  - 2001:db8:1::ffbb
                dns_search:
                  - example.com
              state: up
    
            # Add an Ethernet profile to the bridge
            - name: bridge0-port1
              interface_name: enp7s0
              type: ethernet
              controller: bridge0
              port_type: bridge
              state: up
    
            # Add a second Ethernet profile to the bridge
            - name: bridge0-port2
              interface_name: enp8s0
              type: ethernet
              controller: bridge0
              port_type: bridge
              state: up

    These settings define a network bridge with the following settings:

    • A static IPv4 address - 192.0.2.1 with a /24 subnet mask
    • A static IPv6 address - 2001:db8:1::1 with a /64 subnet mask
    • An IPv4 default gateway - 192.0.2.254
    • An IPv6 default gateway - 2001:db8:1::fffe
    • An IPv4 DNS server - 192.0.2.200
    • An IPv6 DNS server - 2001:db8:1::ffbb
    • A DNS search domain - example.com
    • Ports of the bridge - enp7s0 and enp8s0

      Note

      Set the IP configuration on the bridge and not on the ports of the Linux bridge.

  2. Validate the playbook syntax:

    # ansible-playbook ~/bridge-ethernet.yml --syntax-check

    Note that this command only validates the syntax and does not protect against a wrong but valid configuration.

  3. Run the playbook:

    # ansible-playbook ~/bridge-ethernet.yml

Additional resources

  • /usr/share/ansible/roles/rhel-system-roles.network/README.md file

Chapter 7. Configuring a VPN connection

A virtual private network (VPN) is a way of connecting to a local network over the internet. IPsec provided by Libreswan is the preferred method for creating a VPN. Libreswan is a user-space IPsec implementation for VPN. A VPN enables the communication between your LAN, and another, remote LAN by setting up a tunnel across an intermediate network such as the internet. For security reasons, a VPN tunnel always uses authentication and encryption. For cryptographic operations, Libreswan uses the NSS library.

7.1. Configuring a VPN connection with control-center

If you use Red Hat Enterprise Linux with a graphical interface, you can configure a VPN connection in the GNOME control-center.

Prerequisites

  • The NetworkManager-libreswan-gnome package is installed.

Procedure

  1. Press the Super key, type Settings, and press Enter to open the control-center application.
  2. Select the Network entry on the left.
  3. Click the + icon.
  4. Select VPN.
  5. Select the Identity menu entry to see the basic configuration options:

    General

    Gateway — The name or IP address of the remote VPN gateway.

    Authentication

    Type

    • IKEv2 (Certificate)- client is authenticated by certificate. It is more secure (default).
    • IKEv1 (XAUTH) - client is authenticated by user name and password, or a pre-shared key (PSK).

      The following configuration settings are available under the Advanced section:

      Figure 7.1. Advanced options of a VPN connection

      networking vpn advanced options
      Warning

      When configuring an IPsec-based VPN connection using the gnome-control-center application, the Advanced dialog displays the configuration, but it does not allow any changes. As a consequence, users cannot change any advanced IPsec options. Use the nm-connection-editor or nmcli tools instead to perform configuration of the advanced properties.

      Identification

    • Domain — If required, enter the Domain Name.

      Security

    • Phase1 Algorithms — corresponds to the ike Libreswan parameter — enter the algorithms to be used to authenticate and set up an encrypted channel.
    • Phase2 Algorithms — corresponds to the esp Libreswan parameter — enter the algorithms to be used for the IPsec negotiations.

      Check the Disable PFS field to turn off Perfect Forward Secrecy (PFS) to ensure compatibility with old servers that do not support PFS.

    • Phase1 Lifetime — corresponds to the ikelifetime Libreswan parameter — how long the key used to encrypt the traffic will be valid.
    • Phase2 Lifetime — corresponds to the salifetime Libreswan parameter — how long a particular instance of a connection should last before expiring.

      Note that the encryption key should be changed from time to time for security reasons.

    • Remote network — corresponds to the rightsubnet Libreswan parameter — the destination private remote network that should be reached through the VPN.

      Check the narrowing field to enable narrowing. Note that it is only effective in IKEv2 negotiation.

    • Enable fragmentation — corresponds to the fragmentation Libreswan parameter — whether or not to allow IKE fragmentation. Valid values are yes (default) or no.
    • Enable Mobike — corresponds to the mobike Libreswan parameter — whether to allow Mobility and Multihoming Protocol (MOBIKE, RFC 4555) to enable a connection to migrate its endpoint without needing to restart the connection from scratch. This is used on mobile devices that switch between wired, wireless, or mobile data connections. The values are no (default) or yes.
  6. Select the IPv4 menu entry:

    IPv4 Method

    • Automatic (DHCP) — Choose this option if the network you are connecting to uses a DHCP server to assign dynamic IP addresses.
    • Link-Local Only — Choose this option if the network you are connecting to does not have a DHCP server and you do not want to assign IP addresses manually. Random addresses will be assigned as per RFC 3927 with prefix 169.254/16.
    • Manual — Choose this option if you want to assign IP addresses manually.
    • DisableIPv4 is disabled for this connection.

      DNS

      In the DNS section, when Automatic is ON, switch it to OFF to enter the IP address of a DNS server you want to use separating the IPs by comma.

      Routes

      Note that in the Routes section, when Automatic is ON, routes from DHCP are used, but you can also add additional static routes. When OFF, only static routes are used.

    • Address — Enter the IP address of a remote network or host.
    • Netmask — The netmask or prefix length of the IP address entered above.
    • Gateway — The IP address of the gateway leading to the remote network or host entered above.
    • Metric — A network cost, a preference value to give to this route. Lower values will be preferred over higher values.

      Use this connection only for resources on its network

      Select this check box to prevent the connection from becoming the default route. Selecting this option means that only traffic specifically destined for routes learned automatically over the connection or entered here manually is routed over the connection.

  7. To configure IPv6 settings in a VPN connection, select the IPv6 menu entry:

    IPv6 Method

    • Automatic — Choose this option to use IPv6 Stateless Address AutoConfiguration (SLAAC) to create an automatic, stateless configuration based on the hardware address and Router Advertisements (RA).
    • Automatic, DHCP only — Choose this option to not use RA, but request information from DHCPv6 directly to create a stateful configuration.
    • Link-Local Only — Choose this option if the network you are connecting to does not have a DHCP server and you do not want to assign IP addresses manually. Random addresses will be assigned as per RFC 4862 with prefix FE80::0.
    • Manual — Choose this option if you want to assign IP addresses manually.
    • DisableIPv6 is disabled for this connection.

      Note that DNS, Routes, Use this connection only for resources on its network are common to IPv4 settings.

  8. Once you have finished editing the VPN connection, click the Add button to customize the configuration or the Apply button to save it for the existing one.
  9. Switch the profile to ON to active the VPN connection.

Additional resources

  • nm-settings-libreswan(5)

7.2. Configuring a VPN connection using nm-connection-editor

If you use Red Hat Enterprise Linux with a graphical interface, you can configure a VPN connection in the nm-connection-editor application.

Prerequisites

  • The NetworkManager-libreswan-gnome package is installed.
  • If you configure an Internet Key Exchange version 2 (IKEv2) connection:

    • The certificate is imported into the IPsec network security services (NSS) database.
    • The nickname of the certificate in the NSS database is known.

Procedure

  1. Open a terminal, and enter:

    $ nm-connection-editor
  2. Click the + button to add a new connection.
  3. Select the IPsec based VPN connection type, and click Create.
  4. On the VPN tab:

    1. Enter the host name or IP address of the VPN gateway into the Gateway field, and select an authentication type. Based on the authentication type, you must enter different additional information:

      • IKEv2 (Certifiate) authenticates the client by using a certificate, which is more secure. This setting requires the nickname of the certificate in the IPsec NSS database
      • IKEv1 (XAUTH) authenticates the user by using a user name and password (pre-shared key). This setting requires that you enter the following values:

        • User name
        • Password
        • Group name
        • Secret
    2. If the remote server specifies a local identifier for the IKE exchange, enter the exact string in the Remote ID field. In the remote server runs Libreswan, this value is set in the server’s leftid parameter.

      nm connection editor vpn tab

    3. Optionally, configure additional settings by clicking the Advanced button. You can configure the following settings:

      • Identification

        • Domain — If required, enter the domain name.
      • Security

        • Phase1 Algorithms corresponds to the ike Libreswan parameter. Enter the algorithms to be used to authenticate and set up an encrypted channel.
        • Phase2 Algorithms corresponds to the esp Libreswan parameter. Enter the algorithms to be used for the IPsec negotiations.

          Check the Disable PFS field to turn off Perfect Forward Secrecy (PFS) to ensure compatibility with old servers that do not support PFS.

        • Phase1 Lifetime corresponds to the ikelifetime Libreswan parameter. This parameter defines how long the key used to encrypt the traffic is valid.
        • Phase2 Lifetime corresponds to the salifetime Libreswan parameter. This parameter defines how long a security association is valid.
      • Connectivity

        • Remote network corresponds to the rightsubnet Libreswan parameter and defines the destination private remote network that should be reached through the VPN.

          Check the narrowing field to enable narrowing. Note that it is only effective in the IKEv2 negotiation.

        • Enable fragmentation corresponds to the fragmentation Libreswan parameter and defines whether or not to allow IKE fragmentation. Valid values are yes (default) or no.
        • Enable Mobike corresponds to the mobike Libreswan parameter. The parameter defines whether to allow Mobility and Multihoming Protocol (MOBIKE) (RFC 4555) to enable a connection to migrate its endpoint without needing to restart the connection from scratch. This is used on mobile devices that switch between wired, wireless or mobile data connections. The values are no (default) or yes.
  5. On the IPv4 Settings tab, select the IP assignment method and, optionally, set additional static addresses, DNS servers, search domains, and routes.

    IPsec IPv4 tab

  6. Save the connection.
  7. Close nm-connection-editor.
Note

When you add a new connection by clicking the + button, NetworkManager creates a new configuration file for that connection and then opens the same dialog that is used for editing an existing connection. The difference between these dialogs is that an existing connection profile has a Details menu entry.

Additional resources

  • nm-settings-libreswan(5) man page

7.3. Configuring automatic detection and usage of ESP hardware offload to accelerate an IPsec connection

Offloading Encapsulating Security Payload (ESP) to the hardware accelerates IPsec connections over Ethernet. By default, Libreswan detects if hardware supports this feature and, as a result, enables ESP hardware offload. In case that the feature was disabled or explicitly enabled, you can switch back to automatic detection.

Prerequisites

  • The network card supports ESP hardware offload.
  • The network driver supports ESP hardware offload.
  • The IPsec connection is configured and works.

Procedure

  1. Edit the Libreswan configuration file in the /etc/ipsec.d/ directory of the connection that should use automatic detection of ESP hardware offload support.
  2. Ensure the nic-offload parameter is not set in the connection’s settings.
  3. If you removed nic-offload, restart the ipsec service:

    # systemctl restart ipsec

Verification

If the network card supports ESP hardware offload support, following these steps to verify the result:

  1. Display the tx_ipsec and rx_ipsec counters of the Ethernet device the IPsec connection uses:

    # ethtool -S enp1s0 | egrep "_ipsec"
         tx_ipsec: 10
         rx_ipsec: 10
  2. Send traffic through the IPsec tunnel. For example, ping a remote IP address:

    # ping -c 5 remote_ip_address
  3. Display the tx_ipsec and rx_ipsec counters of the Ethernet device again:

    # ethtool -S enp1s0 | egrep "_ipsec"
         tx_ipsec: 15
         rx_ipsec: 15

    If the counter values have increased, ESP hardware offload works.

Additional resources

7.4. Configuring ESP hardware offload on a bond to accelerate an IPsec connection

Offloading Encapsulating Security Payload (ESP) to the hardware accelerates IPsec connections. If you use a network bond for fail-over reasons, the requirements and the procedure to configure ESP hardware offload are different from those using a regular Ethernet device. For example, in this scenario, you enable the offload support on the bond, and the kernel applies the settings to the ports of the bond.

Prerequisites

  • All network cards in the bond support ESP hardware offload.
  • The network driver supports ESP hardware offload on a bond device. In RHEL, only the ixgbe driver supports this feature.
  • The bond is configured and works.
  • The bond uses the active-backup mode. The bonding driver does not support any other modes for this feature.
  • The IPsec connection is configured and works.

Procedure

  1. Enable ESP hardware offload support on the network bond:

    # nmcli connection modify bond0 ethtool.feature-esp-hw-offload on

    This command enables ESP hardware offload support on the bond0 connection.

  2. Reactivate the bond0 connection:

    # nmcli connection up bond0
  3. Edit the Libreswan configuration file in the /etc/ipsec.d/ directory of the connection that should use ESP hardware offload, and append the nic-offload=yes statement to the connection entry:

    conn example
        ...
        nic-offload=yes
  4. Restart the ipsec service:

    # systemctl restart ipsec

Verification

  1. Display the active port of the bond:

    # grep "Currently Active Slave" /proc/net/bonding/bond0
    Currently Active Slave: enp1s0
  2. Display the tx_ipsec and rx_ipsec counters of the active port:

    # ethtool -S enp1s0 | egrep "_ipsec"
         tx_ipsec: 10
         rx_ipsec: 10
  3. Send traffic through the IPsec tunnel. For example, ping a remote IP address:

    # ping -c 5 remote_ip_address
  4. Display the tx_ipsec and rx_ipsec counters of the active port again:

    # ethtool -S enp1s0 | egrep "_ipsec"
         tx_ipsec: 15
         rx_ipsec: 15

    If the counter values have increased, ESP hardware offload works.

Additional resources

Chapter 8. Setting up a WireGuard VPN

WireGuard is a high-performance VPN solution that runs in the Linux kernel. It uses modern cryptography and is easier to configure than many other VPN solutions. Additionally, WireGuard’s small codebase reduces the surface for attacks and, therefore, improves security. For authentication and encryption, WireGuard uses keys similar to SSH.

Important

WireGuard is provided as a Technology Preview only. Technology Preview features are not supported with Red Hat production Service Level Agreements (SLAs), might not be functionally complete, and Red Hat does not recommend using them for production. These previews provide early access to upcoming product features, enabling customers to test functionality and provide feedback during the development process.

See Technology Preview Features Support Scope on the Red Hat Customer Portal for information about the support scope for Technology Preview features.

To set up a WireGuard VPN, you must complete the following steps. You can perform most steps by using different options:

  1. Create public and private keys for every host in the VPN.
  2. Configure the WireGuard server by using nmcli, nmtui, nm-connection-editor, or the wg-quick service.
  3. Configure firewalld on the WireGuard server by using the command line or graphical interface.
  4. Configure the WireGuard client by using nmcli, nm-connection-editor, or the wg-quick service.

WireGuard operates on the network layer (layer 3). Therefore, you cannot use DHCP and must assign static IP addresses or IPv6 link-local addresses to the tunnel devices on both the server and clients.

Important

You can use WireGuard only if the Federal Information Processing Standard (FIPS) mode in RHEL is disabled.

Note that all hosts that participate in a WireGuard VPN are peers. This documentation uses the terms client to describe hosts that establish a connection and server to describe the host with the fixed hostname or IP address that the clients connect to and optionally route all traffic through this server.

8.1. Protocols and primitives used by WireGuard

WireGuard uses the following protocols and primitives:

  • ChaCha20 for symmetric encryption, authenticated with Poly1305, using Authenticated Encryption with Associated Data (AEAD) construction as described in RFC7539
  • Curve25519 for Elliptic-curve Diffie–Hellman (ECDH) key exchange
  • BLAKE2s for hashing and keyed hashing, as described in RFC7693
  • SipHash24 for hash table keys
  • HKDF for key derivation, as described in RFC5869

8.2. How WireGuard uses tunnel IP addresses, public keys, and remote endpoints

When WireGuard sends a network packet to a peer:

  1. WireGuard reads the destination IP from the packet and compares it to the list of allowed IP addresses in the local configuration. If the peer is not found, WireGuard drops the packet.
  2. If the peer is valid, WireGuard encrypts the packet using the peer’s public key.
  3. The sending host looks up the most recent Internet IP address of the host and sends the encrypted packet to it.

When WireGuard receives a packet:

  1. WireGuard decrypts the packet using private key of the remote host.
  2. WireGuard reads the internal source address from the packet and looks up whether the IP is configured in the list of allowed IP addresses in the settings for the peer on the local host. If the source IP is on the allowlist, WireGuard accepts the packet. If the IP address is not on the list, WireGuard drops the packet.

The association of public keys and allowed IP addresses is called Cryptokey Routing Table. This means that the list of IP addresses behaves similar to a routing table when sending packets, and as a kind of access control list when receiving packets.

8.3. Using a WireGuard client behind NAT and firewalls

WireGuard uses the UDP protocol and transmits data only when a peer sends packets. Stateful firewalls and network address translation (NAT) on routers track connections to enable a peer behind NAT or a firewall to receive packets.

To keep the connection active, WireGuard supports persistent keepalives. This means you can set an interval at which WireGuard sends keepalive packets. By default, the persistent keep-alive feature is disabled to reduce network traffic. Enable this feature on the client if you use the client in a network with NAT or if a firewall closes the connection after some time of inactivity.

8.4. Creating private and public keys to be used in WireGuard connections

WireGuard uses base64-encoded private and public keys to authenticate hosts to each other. Therefore, you must create the keys on each host that participates in the WireGuard VPN.

Important

For secure connections, create different keys for each host, and ensure that you only share the public key with the remote WireGuard host. Do not use the example keys used in this documentation.

Procedure

  1. Install the wireguard-tools package:

    # dnf install wireguard-tools
  2. Create a private key and a corresponding public key for the host:

    # wg genkey | tee /etc/wireguard/$HOSTNAME.private.key | wg pubkey > /etc/wireguard/$HOSTNAME.public.key

    You will need the content of the key files, but not the files themselves. However, Red Hat recommends keeping the files in case that you need to remember the keys in future.

  3. Set secure permissions on the key files:

    # chmod 600 /etc/wireguard/$HOSTNAME.private.key /etc/wireguard/$HOSTNAME.public.key
  4. Display the private key:

    # cat /etc/wireguard/$HOSTNAME.private.key
    YFAnE0psgIdiAF7XR4abxiwVRnlMfeltxu10s/c4JXg=

    You will need the private key to configure the WireGuard connection on the local host. Do not share the private key.

  5. Display the public key:

    # cat /etc/wireguard/$HOSTNAME.public.key
    UtjqCJ57DeAscYKRfp7cFGiQqdONRn69u249Fa4O6BE=

    You will need the public key to configure the WireGuard connection on the remote host.

Additional resources

  • The wg(8) man page

8.5. Configuring a WireGuard server by using nmcli

You can configure the WireGuard server by creating a connection profile in NetworkManager. Use this method to let NetworkManager manage the WireGuard connection.

This procedure assumes the following settings:

  • Server:

    • Private key: YFAnE0psgIdiAF7XR4abxiwVRnlMfeltxu10s/c4JXg=
    • Tunnel IPv4 address: 192.0.2.1/24
    • Tunnel IPv6 address: 2001:db8:1::1/32
  • Client:

    • Public key: bnwfQcC8/g2i4vvEqcRUM2e6Hi3Nskk6G9t4r26nFVM=
    • Tunnel IPv4 address: 192.0.2.2/24
    • Tunnel IPv6 address: 2001:db8:1::2/32

Prerequisites

  • You have generated the public and private key for both the server and client.
  • You know the following information:

    • The private key of the server
    • The static tunnel IP addresses and subnet masks of the client
    • The public key of the client
    • The static tunnel IP addresses and subnet masks of the server

Procedure

  1. Add a NetworkManager WireGuard connection profile:

    # nmcli connection add type wireguard con-name server-wg0 ifname wg0 autoconnect no

    This command creates a profile named server-wg0 and assigns the virtual interface wg0 to it. To prevent the connection from starting automatically after you add it without finalizing the configuration, disable the autoconnect parameter.

  2. Set the tunnel IPv4 address and subnet mask of the server:

    # nmcli connection modify server-wg0 ipv4.method manual ipv4.addresses 192.0.2.1/24
  3. Set the tunnel IPv6 address and subnet mask of the server:

    # nmcli connection modify server-wg0 ipv6.method manual ipv6.addresses 2001:db8:1::1/32
  4. Add the server’s private key to the connection profile:

    # nmcli connection modify server-wg0 wireguard.private-key "YFAnE0psgIdiAF7XR4abxiwVRnlMfeltxu10s/c4JXg="
  5. Set the port for incoming WireGuard connections:

    # nmcli connection modify server-wg0 wireguard.listen-port 51820

    Always set a fixed port number on hosts that receive incoming WireGuard connections. If you do not set a port, WireGuard uses a random free port each time you activate the wg0 interface.

  6. Add peer configurations for each client that you want to allow to communicate with this server. You must add these settings manually, because the nmcli utility does not support setting the corresponding connection properties.

    1. Edit the /etc/NetworkManager/system-connections/server-wg0.nmconnection file, and append:

      [wireguard-peer.bnwfQcC8/g2i4vvEqcRUM2e6Hi3Nskk6G9t4r26nFVM=]
      allowed-ips=192.0.2.2;2001:db8:1::2;
      • The [wireguard-peer.<public_key_of_the_client>] entry defines the peer section of the client, and the section name contains the public key of the client.
      • The allowed-ips parameter sets the tunnel IP addresses of the client that are allowed to send data to this server.

        Add a section for each client.

    2. Reload the server-wg0 connection profile:

      # nmcli connection load /etc/NetworkManager/system-connections/server-wg0.nmconnection
  7. Optional: Configure the connection to start automatically, enter:

    # nmcli connection modify server-wg0 autoconnect yes
  8. Reactivate the server-wg0 connection:

    # nmcli connection up server-wg0

Verification

  1. Display the interface configuration of the wg0 device:

    # wg show wg0
    interface: wg0
      public key: UtjqCJ57DeAscYKRfp7cFGiQqdONRn69u249Fa4O6BE=
      private key: (hidden)
      listening port: 51820
    
    peer: bnwfQcC8/g2i4vvEqcRUM2e6Hi3Nskk6G9t4r26nFVM=
      allowed ips: 192.0.2.2/32, 2001:db8:1::2/128

    To display the private key in the output, use the WG_HIDE_KEYS=never wg show wg0 command.

  2. Display the IP configuration of the wg0 device:

    # ip address show wg0
    20: wg0: <POINTOPOINT,NOARP,UP,LOWER_UP> mtu 1420 qdisc noqueue state UNKNOWN group default qlen 1000
        link/none
        inet 192.0.2.1/24 brd 192.0.2.255 scope global noprefixroute wg0
           valid_lft forever preferred_lft forever
        inet6 2001:db8:1::1/32 scope global noprefixroute
           valid_lft forever preferred_lft forever
        inet6 fe80::3ef:8863:1ce2:844/64 scope link noprefixroute
           valid_lft forever preferred_lft forever

Additional resources

  • The wg(8) man page
  • The WireGuard setting section in the nm-settings(5) man page

8.6. Configuring a WireGuard server by using nmtui

You can configure the WireGuard server by creating a connection profile in NetworkManager. Use this method to let NetworkManager manage the WireGuard connection.

This procedure assumes the following settings:

  • Server:

    • Private key: YFAnE0psgIdiAF7XR4abxiwVRnlMfeltxu10s/c4JXg=
    • Tunnel IPv4 address: 192.0.2.1/24
    • Tunnel IPv6 address: 2001:db8:1::1/32
  • Client:

    • Public key: bnwfQcC8/g2i4vvEqcRUM2e6Hi3Nskk6G9t4r26nFVM=
    • Tunnel IPv4 address: 192.0.2.2/24
    • Tunnel IPv6 address: 2001:db8:1::2/32

Prerequisites

  • You have generated the public and private key for both the server and client.
  • You know the following information:

    • The private key of the server
    • The static tunnel IP addresses and subnet masks of the client
    • The public key of the client
    • The static tunnel IP addresses and subnet masks of the server
  • You installed the NetworkManager-tui package.

Procedure

  1. Start the nmtui application:

    # nmtui
  2. Select Edit a connection, and press Enter.
  3. Select Add, and press Enter.
  4. Select the WireGuard connection type in the list, and press Enter.
  5. In the Edit connection window:

    1. Enter the name of the connection and the virtual interface, such as wg0, that NetworkManager should assign to the connection.
    2. Enter the private key of the server.
    3. Set the listen port number, such as 51820, for incoming WireGuard connections.

      Always set a fixed port number on hosts that receive incoming WireGuard connections. If you do not set a port, WireGuard uses a random free port each time you activate the interface.

      nmtui WireGuard server general
    4. Click Add next to the Peers pane:

      1. Enter the public key of the client.
      2. Set the Allowed IPs field to the tunnel IP addresses of the client that are allowed to send data to this server.
      3. Select OK, and press Enter.

        nmtui WireGuard server peer config
    5. Select Show next to IPv4 Configuration, and press Enter.

      1. Select the IPv4 configuration method Manual.
      2. Enter the tunnel IPv4 address and the subnet mask. Leave the Gateway field empty.
    6. Select Show next to IPv6 Configuration, and press Enter.

      1. Select the IPv6 configuration method Manual.
      2. Enter the tunnel IPv6 address and the subnet mask. Leave the Gateway field empty.
    7. Select OK, and press Enter

      nmtui WireGuard server ip config
  6. In the window with the list of connections, select Back, and press Enter.
  7. In the NetworkManager TUI main window, select Quit, and press Enter.

Verification

  1. Display the interface configuration of the wg0 device:

    # wg show wg0
    interface: wg0
      public key: UtjqCJ57DeAscYKRfp7cFGiQqdONRn69u249Fa4O6BE=
      private key: (hidden)
      listening port: 51820
    
    peer: bnwfQcC8/g2i4vvEqcRUM2e6Hi3Nskk6G9t4r26nFVM=
      allowed ips: 192.0.2.2/32, 2001:db8:1::2/128

    To display the private key in the output, use the WG_HIDE_KEYS=never wg show wg0 command.

  2. Display the IP configuration of the wg0 device:

    # ip address show wg0
    20: wg0: <POINTOPOINT,NOARP,UP,LOWER_UP> mtu 1420 qdisc noqueue state UNKNOWN group default qlen 1000
        link/none
        inet 192.0.2.1/24 brd 192.0.2.255 scope global noprefixroute wg0
           valid_lft forever preferred_lft forever
        inet6 2001:db8:1::1/32 scope global noprefixroute
           valid_lft forever preferred_lft forever
        inet6 fe80::3ef:8863:1ce2:844/64 scope link noprefixroute
           valid_lft forever preferred_lft forever

Additional resources

  • The wg(8) man page

8.7. Configuring a WireGuard server by using nm-connection-editor

You can configure the WireGuard server by creating a connection profile in NetworkManager. Use this method to let NetworkManager manage the WireGuard connection.

Prerequisites

  • You have generated the public and private key for both the server and client.
  • You know the following information:

    • The private key of the server
    • The static tunnel IP addresses and subnet masks of the client
    • The public key of the client
    • The static tunnel IP addresses and subnet masks of the server

Procedure

  1. Open a terminal, and enter:

    # nm-connection-editor
  2. Add a new connection by clicking the + button.
  3. Select the WireGuard connection type, and click Create.
  4. Optional: Update the connection name.
  5. On the General tab, select Connect automatically with priority. Optionally, set a priority value.
  6. On the WireGuard tab:

    1. Enter the name of the virtual interface, such as wg0, that NetworkManager should assign to the connection.
    2. Enter the private key of the server.
    3. Set the listen port number, such as 51820, for incoming WireGuard connections.

      Always set a fixed port number on hosts that receive incoming WireGuard connections. If you do not set a port, WireGuard uses a random free port each time you activate the interface.

    4. Click Add to add peers:

      1. Enter the public key of the client.
      2. Set the Allowed IPs field to the tunnel IP addresses of the client that are allowed to send data to this server.
      3. Click Apply.
  7. On the IPv4 Settings tab:

    1. Select Manual in the Method list.
    2. Click Add to enter the tunnel IPv4 address and the subnet mask. Leave the Gateway field empty.
  8. On the IPv6 Settings tab:

    1. Select Manual in the Method list.
    2. Click Add to enter the tunnel IPv6 address and the subnet mask. Leave the Gateway field empty.
  9. Click Save to store the connection profile.

Verification

  1. Display the interface configuration of the wg0 device:

    # wg show wg0
    interface: wg0
      public key: UtjqCJ57DeAscYKRfp7cFGiQqdONRn69u249Fa4O6BE=
      private key: (hidden)
      listening port: 51820
    
    peer: bnwfQcC8/g2i4vvEqcRUM2e6Hi3Nskk6G9t4r26nFVM=
      allowed ips: 192.0.2.2/32, 2001:db8:1::2/128

    To display the private key in the output, use the WG_HIDE_KEYS=never wg show wg0 command.

  2. Display the IP configuration of the wg0 device:

    # ip address show wg0
    20: wg0: <POINTOPOINT,NOARP,UP,LOWER_UP> mtu 1420 qdisc noqueue state UNKNOWN group default qlen 1000
        link/none
        inet 192.0.2.1/24 brd 192.0.2.255 scope global noprefixroute wg0
           valid_lft forever preferred_lft forever
        inet6 2001:db8:1::1/32 scope global noprefixroute
           valid_lft forever preferred_lft forever
        inet6 fe80::3ef:8863:1ce2:844/64 scope link noprefixroute
           valid_lft forever preferred_lft forever

Additional resources

  • The wg(8) man page

8.8. Configuring a WireGuard server by using the wg-quick service

You can configure the WireGuard server by creating a configuration file in the /etc/wireguard/ directory. Use this method to configure the service independently from NetworkManager.

This procedure assumes the following settings:

  • Server:

    • Private key: YFAnE0psgIdiAF7XR4abxiwVRnlMfeltxu10s/c4JXg=
    • Tunnel IPv4 address: 192.0.2.1/24
    • Tunnel IPv6 address: 2001:db8:1::1/32
  • Client:

    • Public key: bnwfQcC8/g2i4vvEqcRUM2e6Hi3Nskk6G9t4r26nFVM=
    • Tunnel IPv4 address: 192.0.2.2/24
    • Tunnel IPv6 address: 2001:db8:1::2/32

Prerequisites

  • You have generated the public and private key for both the server and client.
  • You know the following information:

    • The private key of the server
    • The static tunnel IP addresses and subnet masks of the client
    • The public key of the client
    • The static tunnel IP addresses and subnet masks of the server

Procedure

  1. Install the wireguard-tools package:

    # dnf install wireguard-tools
  2. Create the /etc/wireguard/wg0.conf file with the following content:

    [Interface]
    Address = 192.0.2.1/24, 2001:db8:1::1/32
    ListenPort = 51820
    PrivateKey = YFAnE0psgIdiAF7XR4abxiwVRnlMfeltxu10s/c4JXg=
    
    [Peer]
    PublicKey = bnwfQcC8/g2i4vvEqcRUM2e6Hi3Nskk6G9t4r26nFVM=
    AllowedIPs = 192.0.2.2, 2001:db8:1::2
    • The [Interface] section describes the WireGuard settings of the interface on the server:

      • Address: A comma-separated list of the server’s tunnel IP addresses.
      • PrivateKey: The private key of the server.
      • ListenPort: The port on which WireGuard listens for incoming UDP connections.

        Always set a fixed port number on hosts that receive incoming WireGuard connections. If you do not set a port, WireGuard uses a random free port each time you activate the wg0 interface.

    • Each [Peer] section describes the settings of one client:

      • PublicKey: The public key of the client.
      • AllowedIPs: The tunnel IP addresses of the client that are allowed to send data to this server.
  3. Enable and start the WireGuard connection:

    # systemctl enable --now wg-quick@wg0

    The systemd instance name must match the name of the configuration file in the /etc/wireguard/ directory without the .conf suffix. The service also uses this name for the virtual network interface.

Verification

  1. Display the interface configuration of the wg0 device:

    # wg show wg0
    interface: wg0
      public key: UtjqCJ57DeAscYKRfp7cFGiQqdONRn69u249Fa4O6BE=
      private key: (hidden)
      listening port: 51820
    
    peer: bnwfQcC8/g2i4vvEqcRUM2e6Hi3Nskk6G9t4r26nFVM=
      allowed ips: 192.0.2.2/32, 2001:db8:1::2/128

    To display the private key in the output, use the WG_HIDE_KEYS=never wg show wg0 command.

  2. Display the IP configuration of the wg0 device:

    # ip address show wg0
    20: wg0: <POINTOPOINT,NOARP,UP,LOWER_UP> mtu 1420 qdisc noqueue state UNKNOWN group default qlen 1000
        link/none
        inet 192.0.2.1/24 scope global wg0
           valid_lft forever preferred_lft forever
        inet6 2001:db8:1::1/32 scope global
           valid_lft forever preferred_lft forever

Additional resources

  • The wg(8) man page
  • The wg-quick(8) man page

8.9. Configuring firewalld on a WireGuard server by using the command line

You must configure the firewalld service on the WireGuard server to allow incoming connections from clients. Additionally, if clients should be able to use the WireGuard server as the default gateway and route all traffic through the tunnel, you must enable masquerading.

Procedure

  1. Open the WireGuard port for incoming connections in the firewalld service:

    # firewall-cmd --permanent --add-port=51820/udp --zone=public
  2. If clients should route all traffic through the tunnel and use the WireGuard server as the default gateway, enable masquerading for the public zone:

    # firewall-cmd --permanent --zone=public --add-masquerade
  3. Reload the firewalld rules.

    # firewall-cmd --reload

Verification

  • Display the configuration of the public zone:

    # firewall-cmd --list-all
    public (active)
      ...
      ports: 51820/udp
      masquerade: yes
      ...

Additional resources

  • The firewall-cmd(1) man page

8.10. Configuring firewalld on a WireGuard server by using the graphical interface

You must configure the firewalld service on the WireGuard server to allow incoming connections from clients. Additionally, if clients should be able to use the WireGuard server as the default gateway and route all traffic through the tunnel, you must enable masquerading.

Procedure

  1. Press the Super key, enter firewall, and select the Firewall application from the results.
  2. Select Permanent in the Configuration list.
  3. Select the public zone.
  4. Allow incoming connections to the WireGuard port:

    1. On the Ports tab, click Add.
    2. Enter the port number you set for incoming WireGuard connections:
    3. Select udp from the Protocol list.
    4. Click OK.
  5. If clients should route all traffic through the tunnel and use the WireGuard server as the default gateway:

    1. Navigate to the Masquerading tab of the public zone.
    2. Select Masquerade zone.
  6. Select OptionsReload Firewalld.

Verification

  • Display the configuration of the public zone:

    # firewall-cmd --list-all
    public (active)
      ...
      ports: 51820/udp
      masquerade: yes
      ...

8.11. Configuring a WireGuard client by using nmcli

You can configure a WireGuard client by creating a connection profile in NetworkManager. Use this method to let NetworkManager manage the WireGuard connection.

This procedure assumes the following settings:

  • Client:

    • Private key: aPUcp5vHz8yMLrzk8SsDyYnV33IhE/k20e52iKJFV0A=
    • Tunnel IPv4 address: 192.0.2.2/24
    • Tunnel IPv6 address: 2001:db8:1::2/32
  • Server:

    • Public key: UtjqCJ57DeAscYKRfp7cFGiQqdONRn69u249Fa4O6BE=
    • Tunnel IPv4 address: 192.0.2.1/24
    • Tunnel IPv6 address: 2001:db8:1::1/32

Prerequisites

  • You have generated the public and private key for both the server and client.
  • You know the following information:

    • The private key of the client
    • The static tunnel IP addresses and subnet masks of the client
    • The public key of the server
    • The static tunnel IP addresses and subnet masks of the server

Procedure

  1. Add a NetworkManager WireGuard connection profile:

    # nmcli connection add type wireguard con-name client-wg0 ifname wg0 autoconnect no

    This command creates a profile named client-wg0 and assigns the virtual interface wg0 to it. To prevent the connection from starting automatically after you add it without finalizing the configuration, disable the autoconnect parameter.

  2. Optional: Configure NetworkManager so that it does not automatically start the client-wg connection:

    # nmcli connection modify client-wg0 autoconnect no
  3. Set the tunnel IPv4 address and subnet mask of the client:

    # nmcli connection modify client-wg0 ipv4.method manual ipv4.addresses 192.0.2.2/24
  4. Set the tunnel IPv6 address and subnet mask of the client:

    # nmcli connection modify client-wg0 ipv6.method manual ipv6.addresses 2001:db8:1::2/32
  5. If you want to route all traffic through the tunnel, set the tunnel IP addresses of the server as the default gateway:

    # nmcli connection modify client-wg0 ipv4.gateway 192.0.2.1 ipv6.gateway 2001:db8:1::1

    Routing all traffic through the tunnel requires that you set, in a later step, the allowed-ips on the this client to 0.0.0.0/0;::/0.

    Note that routing all traffic through the tunnel can impact the connectivity to other hosts based on the server routing and firewall configuration.

  6. Add the client’s private key to the connection profile:

    # nmcli connection modify client-wg0 wireguard.private-key "aPUcp5vHz8yMLrzk8SsDyYnV33IhE/k20e52iKJFV0A="
  7. Add peer configurations for each server that you want to allow to communicate with this client. You must add these settings manually, because the nmcli utility does not support setting the corresponding connection properties.

    1. Edit the /etc/NetworkManager/system-connections/client-wg0.nmconnection file, and append:

      [wireguard-peer.UtjqCJ57DeAscYKRfp7cFGiQqdONRn69u249Fa4O6BE=]
      endpoint=server.example.com:51820
      allowed-ips=192.0.2.1;2001:db8:1::1;
      persistent-keepalive=20
      • The [wireguard-peer.<public_key_of_the_server>] entry defines the peer section of the server, and the section name has the public key of the server.
      • The endpoint parameter sets the hostname or IP address and the port of the server. The client uses this information to establish the connection.
      • The allowed-ips parameter sets a list of IP addresses that can send data to this client. For example, set the parameter to:

        • The tunnel IP addresses of the server to allow only the server to communicate with this client. The value in the example above configures this scenario.
        • 0.0.0.0/0;::/0; to allow any remote IPv4 and IPv6 address to communicate with this client. Use this setting to route all traffic through the tunnel and use the WireGuard server as default gateway.
      • The optional persistent-keepalive parameter defines an interval in seconds in which WireGuard sends a keep alive packet to the server. Set this parameter if you use the client in a network with network address translation (NAT) or if a firewall closes the UDP connection after some time of inactivity.
    2. Reload the client-wg0 connection profile:

      # nmcli connection load /etc/NetworkManager/system-connections/client-wg0.nmconnection
  8. Reactivate the client-wg0 connection:

    # nmcli connection up client-wg0

Verification

  1. Ping the IP addresses of the server:

    # ping 192.0.2.1
    # ping6 2001:db8:1::1
  2. Display the interface configuration of the wg0 device:

    # wg show wg0
    interface: wg0
      public key: bnwfQcC8/g2i4vvEqcRUM2e6Hi3Nskk6G9t4r26nFVM=
      private key: (hidden)
      listening port: 51820
    
    peer: UtjqCJ57DeAscYKRfp7cFGiQqdONRn69u249Fa4O6BE=
      endpoint: server.example.com:51820
      allowed ips: 192.0.2.1/32, 2001:db8:1::1/128
      latest handshake: 1 minute, 41 seconds ago
      transfer: 824 B received, 1.01 KiB sent
      persistent keepalive: every 20 seconds

    To display the private key in the output, use the WG_HIDE_KEYS=never wg show wg0 command.

    Note that the output has only the latest handshake and transfer entries if you have already sent traffic through the VPN tunnel.

  3. Display the IP configuration of the wg0 device:

    # ip address show wg0
    10: wg0: <POINTOPOINT,NOARP,UP,LOWER_UP> mtu 1420 qdisc noqueue state UNKNOWN group default qlen 1000
        link/none
        inet 192.0.2.2/24 brd 192.0.2.255 scope global noprefixroute wg0
           valid_lft forever preferred_lft forever
        inet6 2001:db8:1::2/32 scope global noprefixroute
           valid_lft forever preferred_lft forever
        inet6 fe80::73d9:6f51:ea6f:863e/64 scope link noprefixroute
           valid_lft forever preferred_lft forever

Additional resources

  • The wg(8) man page
  • The WireGuard setting section in the nm-settings(5) man page

8.12. Configuring a WireGuard client by using nmtui

You can configure a WireGuard client by creating a connection profile in NetworkManager. Use this method to let NetworkManager manage the WireGuard connection.

This procedure assumes the following settings:

  • Client:

    • Private key: aPUcp5vHz8yMLrzk8SsDyYnV33IhE/k20e52iKJFV0A=
    • Tunnel IPv4 address: 192.0.2.2/24
    • Tunnel IPv6 address: 2001:db8:1::2/32
  • Server:

    • Public key: UtjqCJ57DeAscYKRfp7cFGiQqdONRn69u249Fa4O6BE=
    • Tunnel IPv4 address: 192.0.2.1/24
    • Tunnel IPv6 address: 2001:db8:1::1/32

Prerequisites

  • You have generated the public and private key for both the server and client.
  • You know the following information:

    • The private key of the client
    • The static tunnel IP addresses and subnet masks of the client
    • The public key of the server
    • The static tunnel IP addresses and subnet masks of the server
  • You installed the NetworkManager-tui package

Procedure

  1. Start the nmtui application:

    # nmtui
  2. Select Edit a connection, and press Enter.
  3. Select Add, and press Enter.
  4. Select the WireGuard connection type in the list, and press Enter.
  5. In the Edit connection window:

    1. Enter the name of the connection and the virtual interface, such as wg0, that NetworkManager should assign to the connection.
    2. Enter the private key of the client.

      nmtui WireGuard client general
    3. Click Add next to the Peers pane:

      1. Enter the public key of the server.
      2. Set the Allowed IPs field. For example, set it to:

        • The tunnel IP addresses of the server to allow only the server to communicate with this client.
        • 0.0.0.0/0,::/0 to allow any remote IPv4 and IPv6 address to communicate with this client. Use this setting to route all traffic through the tunnel and use the WireGuard server as default gateway.
      3. Enter the host name or IP address and port of the WireGuard server into the Endpoint field. Use the following format: hostname_or_IP:port_number
      4. Optional: If you use the client in a network with network address translation (NAT) or if a firewall closes the UDP connection after some time of inactivity, set a persistent keep alive interval in seconds. In this interval, the client sends a keepalive packet to the server.
      5. Select OK, and press Enter.

        nmtui WireGuard client peer config
    4. Select Show next to IPv4 Configuration, and press Enter.

      1. Select the IPv4 configuration method Manual.
      2. Enter the tunnel IPv4 address and the subnet mask. Leave the Gateway field empty.
    5. Select Show next to IPv6 Configuration, and press Enter.

      1. Select the IPv6 configuration method Manual.
      2. Enter the tunnel IPv6 address and the subnet mask. Leave the Gateway field empty.
    6. Optional: Select Automatically connect.
    7. Select OK, and press Enter

      nmtui WireGuard client ip config
  6. In the window with the list of connections, select Back, and press Enter.
  7. In the NetworkManager TUI main window, select Quit, and press Enter.

Verification

  1. Ping the IP addresses of the server:

    # ping 192.0.2.1
    # ping6 2001:db8:1::1
  2. Display the interface configuration of the wg0 device:

    # wg show wg0
    interface: wg0
      public key: bnwfQcC8/g2i4vvEqcRUM2e6Hi3Nskk6G9t4r26nFVM=
      private key: (hidden)
      listening port: 51820
    
    peer: UtjqCJ57DeAscYKRfp7cFGiQqdONRn69u249Fa4O6BE=
      endpoint: server.example.com:51820
      allowed ips: 192.0.2.1/32, 2001:db8:1::1/128
      latest handshake: 1 minute, 41 seconds ago
      transfer: 824 B received, 1.01 KiB sent
      persistent keepalive: every 20 seconds

    To display the private key in the output, use the WG_HIDE_KEYS=never wg show wg0 command.

    Note that the output contains only the latest handshake and transfer entries if you have already sent traffic through the VPN tunnel.

  3. Display the IP configuration of the wg0 device:

    # ip address show wg0
    10: wg0: <POINTOPOINT,NOARP,UP,LOWER_UP> mtu 1420 qdisc noqueue state UNKNOWN group default qlen 1000
        link/none
        inet 192.0.2.2/24 brd 192.0.2.255 scope global noprefixroute wg0
           valid_lft forever preferred_lft forever
        inet6 2001:db8:1::2/32 scope global noprefixroute
           valid_lft forever preferred_lft forever
        inet6 fe80::73d9:6f51:ea6f:863e/64 scope link noprefixroute
           valid_lft forever preferred_lft forever

Additional resources

  • The wg(8) man page

8.13. Configuring a WireGuard client by using nm-connection-editor

You can configure a WireGuard client by creating a connection profile in NetworkManager. Use this method to let NetworkManager manage the WireGuard connection.

Prerequisites

  • You have generated the public and private key for both the server and client.
  • You know the following information:

    • The private key of the client
    • The static tunnel IP addresses and subnet masks of the client
    • The public key of the server
    • The static tunnel IP addresses and subnet masks of the server

Procedure

  1. Open a terminal, and enter:

    # nm-connection-editor
  2. Add a new connection by clicking the + button.
  3. Select the WireGuard connection type, and click Create.
  4. Optional: Update the connection name.
  5. Optional: On the General tab, select Connect automatically with priority.
  6. On the WireGuard tab:

    1. Enter the name of the virtual interface, such as wg0, that NetworkManager should assign to the connection.
    2. Enter client’s private key.
    3. Click Add to add peers:

      1. Enter the public key of the server.
      2. Set the Allowed IPs field. For example, set it to:

        • The tunnel IP addresses of the server to allow only the server to communicate with this client.
        • 0.0.0.0/0;::/0; to allow any remote IPv4 and IPv6 address to communicate with this client. Use this setting to route all traffic through the tunnel and use the WireGuard server as default gateway.

          Note that routing all traffic through the tunnel can impact the connectivity to other hosts based on the server routing and firewall configuration.

      3. Enter the hostname or IP address and port of the WireGuard server into the Endpoint field. Use the following format: hostname_or_IP:port_number
      4. Optional: If you use the client in a network with network address translation (NAT) or if a firewall closes the UDP connection after some time of inactivity, set a persistent keep alive interval in seconds. In this interval, the client sends a keep alive packet to the server.
      5. Click Apply.
  7. On the IPv4 Settings tab:

    1. Select Manual in the Method list.
    2. Click Add to enter the tunnel IPv4 address and the subnet mask.
    3. If you want to route all traffic through the tunnel, set the tunnel IPv4 address of the server in the Gateway field. Otherwise, leave the field empty.

      Routing all IPv4 traffic through the tunnel requires that you included 0.0.0.0/0 in the Allowed IPs field on this client.

  8. On the IPv6 Settings tab:

    1. Select Manual in the Method list.
    2. Click Add to enter the tunnel IPv6 address and the subnet mask.
    3. If you want to route all traffic through the tunnel, set the tunnel IPv6 address of the server in the Gateway field. Otherwise, leave the field empty.

      Routing all IPv4 traffic through the tunnel requires that you included ::/0 in the Allowed IPs field on this client.

  9. Click Save to store the connection profile.

Verification

  1. Ping the IP addresses of the server:

    # ping 192.0.2.1
    # ping6 2001:db8:1::1
  2. Display the interface configuration of the wg0 device:

    # wg show wg0
    interface: wg0
      public key: bnwfQcC8/g2i4vvEqcRUM2e6Hi3Nskk6G9t4r26nFVM=
      private key: (hidden)
      listening port: 51820
    
    peer: UtjqCJ57DeAscYKRfp7cFGiQqdONRn69u249Fa4O6BE=
      endpoint: server.example.com:51820
      allowed ips: 192.0.2.1/32, 2001:db8:1::1/128
      latest handshake: 1 minute, 41 seconds ago
      transfer: 824 B received, 1.01 KiB sent
      persistent keepalive: every 20 seconds

    To display the private key in the output, use the WG_HIDE_KEYS=never wg show wg0 command.

    Note that the output only has the latest handshake and transfer entries if you have already sent traffic through the VPN tunnel.

  3. Display the IP configuration of the wg0 device:

    # ip address show wg0
    10: wg0: <POINTOPOINT,NOARP,UP,LOWER_UP> mtu 1420 qdisc noqueue state UNKNOWN group default qlen 1000
        link/none
        inet 192.0.2.2/24 brd 192.0.2.255 scope global noprefixroute wg0
           valid_lft forever preferred_lft forever
        inet6 2001:db8:1::2/32 scope global noprefixroute
           valid_lft forever preferred_lft forever
        inet6 fe80::73d9:6f51:ea6f:863e/64 scope link noprefixroute
           valid_lft forever preferred_lft forever

Additional resources

  • The wg(8) man page

8.14. Configuring a WireGuard client by using the wg-quick service

You can configure a WireGuard client by creating a configuration file in the /etc/wireguard/ directory. Use this method to configure the service independently from NetworkManager.

This procedure assumes the following settings:

  • Client:

    • Private key: aPUcp5vHz8yMLrzk8SsDyYnV33IhE/k20e52iKJFV0A=
    • Tunnel IPv4 address: 192.0.2.2/24
    • Tunnel IPv6 address: 2001:db8:1::2/32
  • Server:

    • Public key: UtjqCJ57DeAscYKRfp7cFGiQqdONRn69u249Fa4O6BE=
    • Tunnel IPv4 address: 192.0.2.1/24
    • Tunnel IPv6 address: 2001:db8:1::1/32

Prerequisites

  • You have generated the public and private key for both the server and client.
  • You know the following information:

    • The private key of the client
    • The static tunnel IP addresses and subnet masks of the client
    • The public key of the server
    • The static tunnel IP addresses and subnet masks of the server

Procedure

  1. Install the wireguard-tools package:

    # dnf install wireguard-tools
  2. Create the /etc/wireguard/wg0.conf file with the following content:

    [Interface]
    Address = 192.0.2.2/24, 2001:db8:1::2/32
    PrivateKey = aPUcp5vHz8yMLrzk8SsDyYnV33IhE/k20e52iKJFV0A=
    *
    [Peer]
    PublicKey = UtjqCJ57DeAscYKRfp7cFGiQqdONRn69u249Fa4O6BE=
    AllowedIPs = 192.0.2.1, 2001:db8:1::1
    Endpoint = server.example.com:51820
    PersistentKeepalive = 20
    • The [Interface] section describes the WireGuard settings of the interface on the client:

      • Address: A comma-separated list of the client’s tunnel IP addresses.
      • PrivateKey: The private key of the client.
    • The [Peer] section describes the settings of the server:

      • PublicKey: The public key of the server.
      • AllowedIPs: The IP addresses that are allowed to send data to this client. For example, set the parameter to:

        • The tunnel IP addresses of the server to allow only the server to communicate with this client. The value in the example above configures this scenario.
        • 0.0.0.0/0, ::/0 to allow any remote IPv4 and IPv6 address to communicate with this client. Use this setting to route all traffic through the tunnel and use the WireGuard server as default gateway.
      • Endpoint: Sets the hostname or IP address and the port of the server. The client uses this information to establish the connection.
      • The optional persistent-keepalive parameter defines an interval in seconds in which WireGuard sends a keepalive packet to the server. Set this parameter if you use the client in a network with network address translation (NAT) or if a firewall closes the UDP connection after some time of inactivity.
  3. Enable and start the WireGuard connection:

    # systemctl enable --now wg-quick@wg0

    The systemd instance name must match the name of the configuration file in the /etc/wireguard/ directory without the .conf suffix. The service also uses this name for the virtual network interface.

Verification

  1. Ping the IP addresses of the server:

    # ping 192.0.2.1
    # ping6 2001:db8:1::1
  2. Display the interface configuration of the wg0 device:

    # wg show wg0
    interface: wg0
      public key: bnwfQcC8/g2i4vvEqcRUM2e6Hi3Nskk6G9t4r26nFVM=
      private key: (hidden)
      listening port: 51820
    
    peer: UtjqCJ57DeAscYKRfp7cFGiQqdONRn69u249Fa4O6BE=
      endpoint: server.example.com:51820
      allowed ips: 192.0.2.1/32, 2001:db8:1::1/128
      latest handshake: 1 minute, 41 seconds ago
      transfer: 824 B received, 1.01 KiB sent
      persistent keepalive: every 20 seconds

    To display the private key in the output, use the WG_HIDE_KEYS=never wg show wg0 command.

    Note that the output contains only the latest handshake and transfer entries if you have already sent traffic through the VPN tunnel.

  3. Display the IP configuration of the wg0 device:

    # ip address show wg0
    10: wg0: <POINTOPOINT,NOARP,UP,LOWER_UP> mtu 1420 qdisc noqueue state UNKNOWN group default qlen 1000
        link/none
        inet 192.0.2.2/24 scope global wg0
           valid_lft forever preferred_lft forever
        inet6 2001:db8:1::2/32__ scope global
           valid_lft forever preferred_lft forever

Additional resources

  • The wg(8) man page
  • The wg-quick(8) man page

Chapter 9. Configuring IP tunnels

Similar to a VPN, an IP tunnel directly connects two networks over a third network, such as the internet. However, not all tunnel protocols support encryption.

The routers in both networks that establish the tunnel requires at least two interfaces:

  • One interface that is connected to the local network
  • One interface that is connected to the network through which the tunnel is established.

To establish the tunnel, you create a virtual interface on both routers with an IP address from the remote subnet.

NetworkManager supports the following IP tunnels:

  • Generic Routing Encapsulation (GRE)
  • Generic Routing Encapsulation over IPv6 (IP6GRE)
  • Generic Routing Encapsulation Terminal Access Point (GRETAP)
  • Generic Routing Encapsulation Terminal Access Point over IPv6 (IP6GRETAP)
  • IPv4 over IPv4 (IPIP)
  • IPv4 over IPv6 (IPIP6)
  • IPv6 over IPv6 (IP6IP6)
  • Simple Internet Transition (SIT)

Depending on the type, these tunnels act either on layer 2 or 3 of the Open Systems Interconnection (OSI) model.

9.1. Configuring an IPIP tunnel using nmcli to encapsulate IPv4 traffic in IPv4 packets

An IP over IP (IPIP) tunnel operates on OSI layer 3 and encapsulates IPv4 traffic in IPv4 packets as described in RFC 2003.

Important

Data sent through an IPIP tunnel is not encrypted. For security reasons, use the tunnel only for data that is already encrypted, for example, by other protocols, such as HTTPS.

Note that IPIP tunnels support only unicast packets. If you require an IPv4 tunnel that supports multicast, see Configuring a GRE tunnel using nmcli to encapsulate layer-3 traffic in IPv4 packets.

For example, you can create an IPIP tunnel between two RHEL routers to connect two internal subnets over the internet as shown in the following diagram:

IPIP tunnel

Prerequisites

  • Each RHEL router has a network interface that is connected to its local subnet.
  • Each RHEL router has a network interface that is connected to the internet.
  • The traffic you want to send through the tunnel is IPv4 unicast.

Procedure

  1. On the RHEL router in network A:

    1. Create an IPIP tunnel interface named tun0:

      # nmcli connection add type ip-tunnel ip-tunnel.mode ipip con-name tun0 ifname tun0 remote 198.51.100.5 local 203.0.113.10

      The remote and local parameters set the public IP addresses of the remote and the local routers.

    2. Set the IPv4 address to the tun0 device:

      # nmcli connection modify tun0 ipv4.addresses '10.0.1.1/30'

      Note that a /30 subnet with two usable IP addresses is sufficient for the tunnel.

    3. Configure the tun0 connection to use a manual IPv4 configuration:

      # nmcli connection modify tun0 ipv4.method manual
    4. Add a static route that routes traffic to the 172.16.0.0/24 network to the tunnel IP on router B:

      # nmcli connection modify tun0 +ipv4.routes "172.16.0.0/24 10.0.1.2"
    5. Enable the tun0 connection.

      # nmcli connection up tun0
    6. Enable packet forwarding:

      # echo "net.ipv4.ip_forward=1" > /etc/sysctl.d/95-IPv4-forwarding.conf
      # sysctl -p /etc/sysctl.d/95-IPv4-forwarding.conf
  2. On the RHEL router in network B:

    1. Create an IPIP tunnel interface named tun0:

      # nmcli connection add type ip-tunnel ip-tunnel.mode ipip con-name tun0 ifname tun0 remote 203.0.113.10 local 198.51.100.5

      The remote and local parameters set the public IP addresses of the remote and local routers.

    2. Set the IPv4 address to the tun0 device:

      # nmcli connection modify tun0 ipv4.addresses '10.0.1.2/30'
    3. Configure the tun0 connection to use a manual IPv4 configuration:

      # nmcli connection modify tun0 ipv4.method manual
    4. Add a static route that routes traffic to the 192.0.2.0/24 network to the tunnel IP on router A:

      # nmcli connection modify tun0 +ipv4.routes "192.0.2.0/24 10.0.1.1"
    5. Enable the tun0 connection.

      # nmcli connection up tun0
    6. Enable packet forwarding:

      # echo "net.ipv4.ip_forward=1" > /etc/sysctl.d/95-IPv4-forwarding.conf
      # sysctl -p /etc/sysctl.d/95-IPv4-forwarding.conf

Verification

  • From each RHEL router, ping the IP address of the internal interface of the other router:

    1. On Router A, ping 172.16.0.1:

      # ping 172.16.0.1
    2. On Router B, ping 192.0.2.1:

      # ping 192.0.2.1

Additional resources

  • nmcli(1) man page
  • nm-settings(5) man page

9.2. Configuring a GRE tunnel using nmcli to encapsulate layer-3 traffic in IPv4 packets

A Generic Routing Encapsulation (GRE) tunnel encapsulates layer-3 traffic in IPv4 packets as described in RFC 2784. A GRE tunnel can encapsulate any layer 3 protocol with a valid Ethernet type.

Important

Data sent through a GRE tunnel is not encrypted. For security reasons, use the tunnel only for data that is already encrypted, for example, by other protocols, such as HTTPS.

For example, you can create a GRE tunnel between two RHEL routers to connect two internal subnets over the internet as shown in the following diagram:

GRE tunnel
Note

The gre0 device name is reserved. Use gre1 or a different name for the device.

Prerequisites

  • Each RHEL router has a network interface that is connected to its local subnet.
  • Each RHEL router has a network interface that is connected to the internet.

Procedure

  1. On the RHEL router in network A:

    1. Create a GRE tunnel interface named gre1:

      # nmcli connection add type ip-tunnel ip-tunnel.mode gre con-name gre1 ifname gre1 remote 198.51.100.5 local 203.0.113.10

      The remote and local parameters set the public IP addresses of the remote and the local routers.

    2. Set the IPv4 address to the gre1 device:

      # nmcli connection modify gre1 ipv4.addresses '10.0.1.1/30'

      Note that a /30 subnet with two usable IP addresses is sufficient for the tunnel.

    3. Configure the gre1 connection to use a manual IPv4 configuration:

      # nmcli connection modify gre1 ipv4.method manual
    4. Add a static route that routes traffic to the 172.16.0.0/24 network to the tunnel IP on router B:

      # nmcli connection modify gre1 +ipv4.routes "172.16.0.0/24 10.0.1.2"
    5. Enable the gre1 connection.

      # nmcli connection up gre1
    6. Enable packet forwarding:

      # echo "net.ipv4.ip_forward=1" > /etc/sysctl.d/95-IPv4-forwarding.conf
      # sysctl -p /etc/sysctl.d/95-IPv4-forwarding.conf
  2. On the RHEL router in network B:

    1. Create a GRE tunnel interface named gre1:

      # nmcli connection add type ip-tunnel ip-tunnel.mode gre con-name gre1 ifname gre1 remote 203.0.113.10 local 198.51.100.5

      The remote and local parameters set the public IP addresses of the remote and the local routers.

    2. Set the IPv4 address to the gre1 device:

      # nmcli connection modify gre1 ipv4.addresses '10.0.1.2/30'
    3. Configure the gre1 connection to use a manual IPv4 configuration:

      # nmcli connection modify gre1 ipv4.method manual
    4. Add a static route that routes traffic to the 192.0.2.0/24 network to the tunnel IP on router A:

      # nmcli connection modify gre1 +ipv4.routes "192.0.2.0/24 10.0.1.1"
    5. Enable the gre1 connection.

      # nmcli connection up gre1
    6. Enable packet forwarding:

      # echo "net.ipv4.ip_forward=1" > /etc/sysctl.d/95-IPv4-forwarding.conf
      # sysctl -p /etc/sysctl.d/95-IPv4-forwarding.conf

Verification

  1. From each RHEL router, ping the IP address of the internal interface of the other router:

    1. On Router A, ping 172.16.0.1:

      # ping 172.16.0.1
    2. On Router B, ping 192.0.2.1:

      # ping 192.0.2.1

Additional resources

  • nmcli(1) man page
  • nm-settings(5) man page

9.3. Configuring a GRETAP tunnel to transfer Ethernet frames over IPv4

A Generic Routing Encapsulation Terminal Access Point (GRETAP) tunnel operates on OSI level 2 and encapsulates Ethernet traffic in IPv4 packets as described in RFC 2784.

Important

Data sent through a GRETAP tunnel is not encrypted. For security reasons, establish the tunnel over a VPN or a different encrypted connection.

For example, you can create a GRETAP tunnel between two RHEL routers to connect two networks using a bridge as shown in the following diagram:

GRETAP tunnel
Note

The gretap0 device name is reserved. Use gretap1 or a different name for the device.

Prerequisites

  • Each RHEL router has a network interface that is connected to its local network, and the interface has no IP configuration assigned.
  • Each RHEL router has a network interface that is connected to the internet.

Procedure

  1. On the RHEL router in network A:

    1. Create a bridge interface named bridge0:

      # nmcli connection add type bridge con-name bridge0 ifname bridge0
    2. Configure the IP settings of the bridge:

      # nmcli connection modify bridge0 ipv4.addresses '192.0.2.1/24'
      # nmcli connection modify bridge0 ipv4.method manual
    3. Add a new connection profile for the interface that is connected to local network to the bridge:

      # nmcli connection add type ethernet slave-type bridge con-name bridge0-port1 ifname enp1s0 master bridge0
    4. Add a new connection profile for the GRETAP tunnel interface to the bridge:

      # nmcli connection add type ip-tunnel ip-tunnel.mode gretap slave-type bridge con-name bridge0-port2 ifname gretap1 remote 198.51.100.5 local 203.0.113.10 master bridge0

      The remote and local parameters set the public IP addresses of the remote and the local routers.

    5. Optional: Disable the Spanning Tree Protocol (STP) if you do not need it:

      # nmcli connection modify bridge0 bridge.stp no

      By default, STP is enabled and causes a delay before you can use the connection.

    6. Configure that activating the bridge0 connection automatically activates the ports of the bridge:

      # nmcli connection modify bridge0 connection.autoconnect-slaves 1
    7. Active the bridge0 connection:

      # nmcli connection up bridge0
  2. On the RHEL router in network B:

    1. Create a bridge interface named bridge0:

      # nmcli connection add type bridge con-name bridge0 ifname bridge0
    2. Configure the IP settings of the bridge:

      # nmcli connection modify bridge0 ipv4.addresses '192.0.2.2/24'
      # nmcli connection modify bridge0 ipv4.method manual
    3. Add a new connection profile for the interface that is connected to local network to the bridge:

      # nmcli connection add type ethernet slave-type bridge con-name bridge0-port1 ifname enp1s0 master bridge0
    4. Add a new connection profile for the GRETAP tunnel interface to the bridge:

      # nmcli connection add type ip-tunnel ip-tunnel.mode gretap slave-type bridge con-name bridge0-port2 ifname gretap1 remote 203.0.113.10 local 198.51.100.5 master bridge0

      The remote and local parameters set the public IP addresses of the remote and the local routers.

    5. Optional: Disable the Spanning Tree Protocol (STP) if you do not need it:

      # nmcli connection modify bridge0 bridge.stp no
    6. Configure that activating the bridge0 connection automatically activates the ports of the bridge:

      # nmcli connection modify bridge0 connection.autoconnect-slaves 1
    7. Active the bridge0 connection:

      # nmcli connection up bridge0

Verification

  1. On both routers, verify that the enp1s0 and gretap1 connections are connected and that the CONNECTION column displays the connection name of the port:

    # nmcli device
    nmcli device
    DEVICE   TYPE      STATE      CONNECTION
    ...
    bridge0  bridge    connected  bridge0
    enp1s0   ethernet  connected  bridge0-port1
    gretap1  iptunnel  connected  bridge0-port2
  2. From each RHEL router, ping the IP address of the internal interface of the other router:

    1. On Router A, ping 192.0.2.2:

      # ping 192.0.2.2
    2. On Router B, ping 192.0.2.1:

      # ping 192.0.2.1

Additional resources

  • nmcli(1) man page
  • nm-settings(5) man page

9.4. Additional resources

  • ip-link(8) man page

Chapter 10. Using a VXLAN to create a virtual layer-2 domain for VMs

A virtual extensible LAN (VXLAN) is a networking protocol that tunnels layer-2 traffic over an IP network using the UDP protocol. For example, certain virtual machines (VMs), that are running on different hosts can communicate over a VXLAN tunnel. The hosts can be in different subnets or even in different data centers around the world. From the perspective of the VMs, other VMs in the same VXLAN are within the same layer-2 domain:

vxlan tunnel

In this example, RHEL-host-A and RHEL-host-B use a bridge, br0, to connect the virtual network of a VM on each host with a VXLAN named vxlan10. Due to this configuration, the VXLAN is invisible to the VMs, and the VMs do not require any special configuration. If you later connect more VMs to the same virtual network, the VMs are automatically members of the same virtual layer-2 domain.

Important

Just as normal layer-2 traffic, data in a VXLAN is not encrypted. For security reasons, use a VXLAN over a VPN or other types of encrypted connections.

10.1. Benefits of VXLANs

A virtual extensible LAN (VXLAN) provides the following major benefits:

  • VXLANs use a 24-bit ID. Therefore, you can create up to 16,777,216 isolated networks. For example, a virtual LAN (VLAN), supports only 4,096 isolated networks.
  • VXLANs use the IP protocol. This enables you to route the traffic and virtually run systems in different networks and locations within the same layer-2 domain.
  • Unlike most tunnel protocols, a VXLAN is not only a point-to-point network. A VXLAN can learn the IP addresses of the other endpoints either dynamically or use statically-configured forwarding entries.
  • Certain network cards support UDP tunnel-related offload features.

Additional resources

  • /usr/share/doc/kernel-doc-<kernel_version>/Documentation/networking/vxlan.rst provided by the kernel-doc package

10.2. Configuring the Ethernet interface on the hosts

To connect a RHEL VM host to the Ethernet, create a network connection profile, configure the IP settings, and activate the profile.

Run this procedure on both RHEL hosts, and adjust the IP address configuration accordingly.

Prerequisites

  • The host is connected to the Ethernet.

Procedure

  1. Add a new Ethernet connection profile to NetworkManager:

    # nmcli connection add con-name Example ifname enp1s0 type ethernet
  2. Configure the IPv4 settings:

    # nmcli connection modify Example ipv4.addresses 198.51.100.2/24 ipv4.method manual ipv4.gateway 198.51.100.254 ipv4.dns 198.51.100.200 ipv4.dns-search example.com

    Skip this step if the network uses DHCP.

  3. Activate the Example connection:

    # nmcli connection up Example

Verification

  1. Display the status of the devices and connections:

    # nmcli device status
    DEVICE      TYPE      STATE      CONNECTION
    enp1s0      ethernet  connected  Example
  2. Ping a host in a remote network to verify the IP settings:

    # ping RHEL-host-B.example.com

    Note that you cannot ping the other VM host before you have configured the network on that host as well.

Additional resources

  • nm-settings(5) man page

10.3. Creating a network bridge with a VXLAN attached

To make a virtual extensible LAN (VXLAN) invisible to virtual machines (VMs), create a bridge on a host, and attach the VXLAN to the bridge. Use NetworkManager to create both the bridge and the VXLAN. You do not add any traffic access point (TAP) devices of the VMs, typically named vnet* on the host, to the bridge. The libvirtd service adds them dynamically when the VMs start.

Run this procedure on both RHEL hosts, and adjust the IP addresses accordingly.

Procedure

  1. Create the bridge br0:

    # nmcli connection add type bridge con-name br0 ifname br0 ipv4.method disabled ipv6.method disabled

    This command sets no IPv4 and IPv6 addresses on the bridge device, because this bridge works on layer 2.

  2. Create the VXLAN interface and attach it to br0:

    # nmcli connection add type vxlan slave-type bridge con-name br0-vxlan10 ifname vxlan10 id 10 local 198.51.100.2 remote 203.0.113.1 master br0

    This command uses the following settings:

    • id 10: Sets the VXLAN identifier.
    • local 198.51.100.2: Sets the source IP address of outgoing packets.
    • remote 203.0.113.1: Sets the unicast or multicast IP address to use in outgoing packets when the destination link layer address is not known in the VXLAN device forwarding database.
    • master br0: Sets this VXLAN connection to be created as a port in the br0 connection.
    • ipv4.method disabled and ipv6.method disabled: Disables IPv4 and IPv6 on the bridge.

    By default, NetworkManager uses 8472 as the destination port. If the destination port is different, additionally, pass the destination-port <port_number> option to the command.

  3. Activate the br0 connection profile:

    # nmcli connection up br0
  4. Open port 8472 for incoming UDP connections in the local firewall:

    # firewall-cmd --permanent --add-port=8472/udp
    # firewall-cmd --reload

Verification

  • Display the forwarding table:

    # bridge fdb show dev vxlan10
    2a:53:bd:d5:b3:0a master br0 permanent
    00:00:00:00:00:00 dst 203.0.113.1 self permanent
    ...

Additional resources

  • nm-settings(5) man page

10.4. Creating a virtual network in libvirt with an existing bridge

To enable virtual machines (VM) to use the br0 bridge with the attached virtual extensible LAN (VXLAN), first add a virtual network to the libvirtd service that uses this bridge.

Prerequisites

  • You installed the libvirt package.
  • You started and enabled the libvirtd service.
  • You configured the br0 device with the VXLAN on RHEL.

Procedure

  1. Create the ~/vxlan10-bridge.xml file with the following content:

    <network>
     <name>vxlan10-bridge</name>
     <forward mode="bridge" />
     <bridge name="br0" />
    </network>
  2. Use the ~/vxlan10-bridge.xml file to create a new virtual network in libvirt:

    # virsh net-define ~/vxlan10-bridge.xml
  3. Remove the ~/vxlan10-bridge.xml file:

    # rm ~/vxlan10-bridge.xml
  4. Start the vxlan10-bridge virtual network:

    # virsh net-start vxlan10-bridge
  5. Configure the vxlan10-bridge virtual network to start automatically when the libvirtd service starts:

    # virsh net-autostart vxlan10-bridge

Verification

  • Display the list of virtual networks:

    # virsh net-list
     Name              State    Autostart   Persistent
    ----------------------------------------------------
     vxlan10-bridge    active   yes         yes
     ...

Additional resources

  • virsh(1) man page

10.5. Configuring virtual machines to use VXLAN

To configure a VM to use a bridge device with an attached virtual extensible LAN (VXLAN) on the host, create a new VM that uses the vxlan10-bridge virtual network or update the settings of existing VMs to use this network.

Perform this procedure on the RHEL hosts.

Prerequisites

  • You configured the vxlan10-bridge virtual network in libvirtd.

Procedure

  • To create a new VM and configure it to use the vxlan10-bridge network, pass the --network network:vxlan10-bridge option to the virt-install command when you create the VM:

    # virt-install ... --network network:vxlan10-bridge
  • To change the network settings of an existing VM:

    1. Connect the VM’s network interface to the vxlan10-bridge virtual network:

      # virt-xml VM_name --edit --network network=vxlan10-bridge
    2. Shut down the VM, and start it again:

      # virsh shutdown VM_name
      # virsh start VM_name

Verification

  1. Display the virtual network interfaces of the VM on the host:

    # virsh domiflist VM_name
     Interface   Type     Source           Model    MAC
    -------------------------------------------------------------------
     vnet1       bridge   vxlan10-bridge   virtio   52:54:00:c5:98:1c
  2. Display the interfaces attached to the vxlan10-bridge bridge:

    # ip link show master vxlan10-bridge
    18: vxlan10: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue master br0 state UNKNOWN mode DEFAULT group default qlen 1000
        link/ether 2a:53:bd:d5:b3:0a brd ff:ff:ff:ff:ff:ff
    19: vnet1: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue master br0 state UNKNOWN mode DEFAULT group default qlen 1000
        link/ether 52:54:00:c5:98:1c brd ff:ff:ff:ff:ff:ff

    Note that the libvirtd service dynamically updates the bridge’s configuration. When you start a VM which uses the vxlan10-bridge network, the corresponding vnet* device on the host appears as a port of the bridge.

  3. Use address resolution protocol (ARP) requests to verify whether VMs are in the same VXLAN:

    1. Start two or more VMs in the same VXLAN.
    2. Send an ARP request from one VM to the other one:

      # arping -c 1 192.0.2.2
      ARPING 192.0.2.2 from 192.0.2.1 enp1s0
      Unicast reply from 192.0.2.2 [52:54:00:c5:98:1c] 1.450ms
      Sent 1 probe(s) (0 broadcast(s))
      Received 1 response(s) (0 request(s), 0 broadcast(s))

      If the command shows a reply, the VM is in the same layer-2 domain and, in this case in the same VXLAN.

      Install the iputils package to use the arping utility.

Additional resources

  • virt-install(1) man page
  • virt-xml(1) man page
  • virsh(1) man page
  • arping(8) man page

Chapter 11. Managing wifi connections

RHEL provides multiple utilities and applications to configure and connect to wifi networks, for example:

  • Use the nmcli utility to configure connections by using the command line.
  • Use the nmtui application to configure connections in a text-based user interface.
  • Use the GNOME system menu to quickly connect to wifi networks that do not require any configuration.
  • Use the GNOME Settings application to configure connections by using the GNOME application.
  • Use the nm-connection-editor application to configure connections in a graphical user interface.
  • Use the network RHEL System Role to automate the configuration of connections on one or multiple hosts.

11.1. Supported wifi security types

Depending on the security type a wifi network supports, you can transmitted data more or less securely.

Warning

Do not connect to wifi networks that do not use encryption or which support only the insecure WEP or WPA standards.

Red Hat Enterprise Linux 9 supports the following wifi security types:

  • None: Encryption is disabled, and data is transferred in plain text over the network.
  • Enhanced Open: With opportunistic wireless encryption (OWE), devices negotiate unique pairwise master keys (PMK) to encrypt connections in wireless networks without authentication.
  • LEAP: The Lightweight Extensible Authentication Protocol, which was developed by Cisco, is a proprietary version of the extensible authentication protocol (EAP).
  • WPA & WPA2 Personal: In personal mode, the Wi-Fi Protected Access (WPA) and Wi-Fi Protected Access 2 (WPA2) authentication methods use a pre-shared key.
  • WPA & WPA2 Enterprise: In enterprise mode, WPA and WPA2 use the EAP framework and authenticate users to a remote authentication dial-in user service (RADIUS) server.
  • WPA3 Personal: Wi-Fi Protected Access 3 (WPA3) Personal uses simultaneous authentication of equals (SAE) instead of pre-shared keys (PSK) to prevent dictionary attacks. WPA3 uses perfect forward secrecy (PFS).

11.2. Connecting to a wifi network by using nmcli

You can use the nmcli utility to connect to a wifi network. When you attempt to connect to a network for the first time, the utility automatically creates a NetworkManager connection profile for it. If the network requires additional settings, such as static IP addresses, you can then modify the profile after it has been automatically created.

Prerequisites

  • A wifi device is installed on the host.
  • The wifi device is enabled, if it has a hardware switch.

Procedure

  1. If the wifi radio has been disabled in NetworkManager, enable this feature:

    # nmcli radio wifi on
  2. Optional: Display the available wifi networks:

    # nmcli device wifi list
    IN-USE  BSSID              SSID          MODE   CHAN  RATE        SIGNAL  BARS  SECURITY
            00:53:00:2F:3B:08  Office        Infra  44    270 Mbit/s  57      ▂▄▆_  WPA2 WPA3
            00:53:00:15:03:BF  --            Infra  1     130 Mbit/s  48      ▂▄__  WPA2 WPA3

    The service set identifier (SSID) column contains the names of the networks. If the column shows --, the access point of this network does not broadcast an SSID.

  3. Connect to the wifi network:

    # nmcli device wifi connect Office --ask
    Password: wifi-password

    If you prefer to set the password in the command instead of entering it interactively, use the password wifi-password option in the command instead of --ask:

    # nmcli device wifi connect Office wifi-password

    Note that, if the network requires static IP addresses, NetworkManager fails to activate the connection at this point. You can configure the IP addresses in later steps.

  4. If the network requires static IP addresses:

    1. Configure the IPv4 address settings, for example:

      # nmcli connection modify Office ipv4.method manual ipv4.addresses 192.0.2.1/24 ipv4.gateway 192.0.2.254 ipv4.dns 192.0.2.200 ipv4.dns-search example.com
    2. Configure the IPv6 address settings, for example:

      # nmcli connection modify Office ipv6.method manual ipv6.addresses 2001:db8:1::1/64 ipv6.gateway 2001:db8:1::fffe ipv6.dns 2001:db8:1::ffbb ipv6.dns-search example.com
  5. Re-activate the connection:

    # nmcli connection up Office

Verification

  1. Display the active connections:

    # nmcli connection show --active
    NAME    ID                                    TYPE  DEVICE
    Office  2501eb7e-7b16-4dc6-97ef-7cc460139a58  wifi  wlp0s20f3

    If the output lists the wifi connection you have created, the connection is active.

  2. Ping a hostname or IP address:

    # ping -c 3 example.com

Additional resources

  • nm-settings-nmcli(5) man page

11.3. Connecting to a wifi network by using the GNOME system menu

You can use the GNOME system menu to connect to a wifi network. When you connect to a network for the first time, GNOME creates a NetworkManager connection profile for it. If you configure the connection profile to not automatically connect, you can also use the GNOME system menu to manually connect to a wifi network with an existing NetworkManager connection profile.

Note

Using the GNOME system menu to establish a connection to a wifi network for the first time has certain limitations. For example, you can not configure IP address settings. In this case first configure the connections:

Prerequisites

  • A wifi device is installed on the host.
  • The wifi device is enabled, if it has a hardware switch.

Procedure

  1. Open the system menu on the right side of the top bar.
  2. Expand the Wi-Fi Not Connected entry.
  3. Click Select Network:

    gnome select wifi
  4. Select the wifi network you want to connect to.
  5. Click Connect.
  6. If this is the first time you connect to this network, enter the password for the network, and click Connect.

Verification

  1. Open the system menu on the right side of the top bar, and verify that the wifi network is connected:

    gnome wifi connected

    If the network appears in the list, it is connected.

  2. Ping a hostname or IP address:

    # ping -c 3 example.com

11.4. Connecting to a wifi network by using the GNOME settings application

You can use the GNOME settings application, also named gnome-control-center, to connect to a wifi network and configure the connection. When you connect to the network for the first time, GNOME creates a NetworkManager connection profile for it.

In GNOME settings, you can configure wifi connections for all wifi network security types that RHEL supports.

Prerequisites

  • A wifi device is installed on the host.
  • The wifi device is enabled, if it has a hardware switch.

Procedure

  1. Press the Super key, type Wi-Fi, and press Enter.
  2. Click on the name of the wifi network you want to connect to.
  3. Enter the password for the network, and click Connect.
  4. If the network requires additional settings, such as static IP addresses or a security type other than WPA2 Personal:

    1. Click the gear icon next to the network’s name.
    2. Optional: Configure the network profile on the Details tab to not automatically connect.

      If you deactivate this feature, you must always manually connect to the network, for example, by using GNOME settings or the GNOME system menu.

    3. Configure IPv4 settings on the IPv4 tab, and IPv6 settings on the IPv6 tab.
    4. On the Security tab, select the authentication of the network, such as WPA3 Personal, and enter the password.

      Depending on the selected security, the application shows additional fields. Fill them accordingly. For details, ask the administrator of the wifi network.

    5. Click Apply.

Verification

  1. Open the system menu on the right side of the top bar, and verify that the wifi network is connected:

    gnome wifi connected

    If the network appears in the list, it is connected.

  2. Ping a hostname or IP address:

    # ping -c 3 example.com

11.5. Configuring a wifi connection by using nmtui

The nmtui application provides a text-based user interface for NetworkManager. You can use nmtui to connect to a wifi network.

Note

In nmtui:

  • Navigate by using the cursor keys.
  • Press a button by selecting it and hitting Enter.
  • Select and deselect checkboxes by using Space.

Procedure

  1. If you do not know the network device name you want to use in the connection, display the available devices:

    # nmcli device status
    DEVICE     TYPE      STATE                   CONNECTION
    wlp2s0    wifi      unavailable             --
    ...
  2. Start nmtui:

    # nmtui
  3. Select Edit a connection, and press Enter.
  4. Press the Add button.
  5. Select Wi-Fi from the list of network types, and press Enter.
  6. Optional: Enter a name for the NetworkManager profile to be created.

    On hosts with multiple profiles, a meaningful name makes it easier to identify the purpose of a profile.

  7. Enter the network device name into the Device field.
  8. Enter the name of the Wi-Fi network, the Service Set Identifier (SSID), into the SSID field.
  9. Leave the Mode field set to its default, Client.
  10. Select the Security field, press Enter, and set the authentication type of the network from the list.

    Depending on the authentication type you have selected, nmtui displays different fields.

  11. Fill the authentication type-related fields.
  12. If the Wi-Fi network requires static IP addresses:

    1. Press the Automatic button next to the protocol, and select Manual from the displayed list.
    2. Press the Show button next to the protocol you want to configure to display additional fields, and fill them.
  13. Press the OK button to create and automatically activate the new connection.

    nmtui wi fi dynamic IP
  14. Press the Back button to return to the main menu.
  15. Select Quit, and press Enter to close the nmtui application.

Verification

  1. Display the active connections:

    # nmcli connection show --active
    NAME    ID                                    TYPE  DEVICE
    Office  2501eb7e-7b16-4dc6-97ef-7cc460139a58  wifi  wlp0s20f3

    If the output lists the wifi connection you have created, the connection is active.

  2. Ping a hostname or IP address:

    # ping -c 3 example.com

11.6. Configuring a wifi connection by using nm-connection-editor

You can use the nm-connection-editor application to create a connection profile for a wireless network. In this application you can configure all wifi network authentication types that RHEL supports.

By default, NetworkManager enables the auto-connect feature for connection profiles and automatically connects to a saved network if it is available.

Prerequisites

  • A wifi device is installed on the host.
  • The wifi device is enabled, if it has a hardware switch.

Procedure

  1. Open a terminal and enter:

    # nm-connection-editor
  2. Click the + button to add a new connection.
  3. Select the Wi-Fi connection type, and click Create.
  4. Optional: Set a name for the connection profile.
  5. Optional: Configure the network profile on the General tab to not automatically connect.

    If you deactivate this feature, you must always manually connect to the network, for example, by using GNOME settings or the GNOME system menu.

  6. On the Wi-Fi tab, enter the service set identifier (SSID) in the SSID field.
  7. On the Wi-Fi Security tab, select the authentication type for the network, such as WPA3 Personal, and enter the password.

    Depending on the selected security, the application shows additional fields. Fill them accordingly. For details, ask the administrator of the wifi network.

  8. Configure IPv4 settings on the IPv4 tab, and IPv6 settings on the IPv6 tab.
  9. Click Save.
  10. Close the Network Connections window.

Verification

  1. Open the system menu on the right side of the top bar, and verify that the wifi network is connected:

    gnome wifi connected

    If the network appears in the list, it is connected.

  2. Ping a hostname or IP address:

    # ping -c 3 example.com

11.7. Configuring a wifi connection with 802.1X network authentication by using the network RHEL System Role

Using RHEL System Roles, you can automate the creation of a wifi connection. For example, you can remotely add a wireless connection profile for the wlp1s0 interface using an Ansible Playbook. The created profile uses the 802.1X standard to authenticate the client to a wifi network. The playbook configures the connection profile to use DHCP. To configure static IP settings, adapt the parameters in the ip dictionary accordingly.

Perform this procedure on the Ansible control node.

Prerequisites

  • You have prepared the control node and the managed nodes
  • You are logged in to the control node as a user who can run playbooks on the managed nodes.
  • The account you use to connect to the managed nodes has sudo permissions on them.
  • The managed nodes or groups of managed nodes on which you want to run this playbook are listed in the Ansible inventory file.
  • The network supports 802.1X network authentication.
  • You installed the wpa_supplicant package on the managed node.
  • DHCP is available in the network of the managed node.
  • The following files required for TLS authentication exist on the control node:

    • The client key is stored in the /srv/data/client.key file.
    • The client certificate is stored in the /srv/data/client.crt file.
    • The CA certificate is stored in the /srv/data/ca.crt file.

Procedure

  1. Create a playbook file, for example ~/enable-802.1x.yml, with the following content:

    ---
    - name: Configure a wifi connection with 802.1X authentication
      hosts: managed-node-01.example.com
      tasks:
        - name: Copy client key for 802.1X authentication
          copy:
            src: "/srv/data/client.key"
            dest: "/etc/pki/tls/private/client.key"
            mode: 0400
    
        - name: Copy client certificate for 802.1X authentication
          copy:
            src: "/srv/data/client.crt"
            dest: "/etc/pki/tls/certs/client.crt"
    
        - name: Copy CA certificate for 802.1X authentication
          copy:
            src: "/srv/data/ca.crt"
            dest: "/etc/pki/ca-trust/source/anchors/ca.crt"
    
        - block:
            - import_role:
                name: linux-system-roles.network
              vars:
                network_connections:
                  - name: Configure the Example-wifi profile
                    interface_name: wlp1s0
                    state: up
                    type: wireless
                    autoconnect: yes
                    ip:
                      dhcp4: true
                      auto6: true
                    wireless:
                      ssid: "Example-wifi"
                      key_mgmt: "wpa-eap"
                    ieee802_1x:
                      identity: "user_name"
                      eap: tls
                      private_key: "/etc/pki/tls/client.key"
                      private_key_password: "password"
                      private_key_password_flags: none
                      client_cert: "/etc/pki/tls/client.pem"
                      ca_cert: "/etc/pki/tls/cacert.pem"
                      domain_suffix_match: "example.com"

    These settings define a wifi connection profile for the wlp1s0 interface. The profile uses 802.1X standard to authenticate the client to the wifi network. The connection retrieves IPv4 addresses, IPv6 addresses, default gateway, routes, DNS servers, and search domains from a DHCP server and IPv6 stateless address autoconfiguration (SLAAC).

  2. Validate the playbook syntax:

    # ansible-playbook ~/enable-802.1x.yml --syntax-check

    Note that this command only validates the syntax and does not protect against a wrong but valid configuration.

  3. Run the playbook:

    # ansible-playbook ~/enable-802.1x.yml

Additional resources

  • /usr/share/ansible/roles/rhel-system-roles.network/README.md file

11.8. Configuring a wifi connection with 802.1X network authentication in an existing profile by using nmcli

Using the nmcli utility, you can configure the client to authenticate itself to the network. For example, you can configure Protected Extensible Authentication Protocol (PEAP) authentication with the Microsoft Challenge-Handshake Authentication Protocol version 2 (MSCHAPv2) in an existing NetworkManager wifi connection profile named wlp1s0.

Prerequisites

  • The network must have 802.1X network authentication.
  • The wifi connection profile exists in NetworkManager and has a valid IP configuration.
  • If the client is required to verify the certificate of the authenticator, the Certificate Authority (CA) certificate must be stored in the /etc/pki/ca-trust/source/anchors/ directory.
  • The wpa_supplicant package is installed.

Procedure

  1. Set the wifi security mode to wpa-eap, the Extensible Authentication Protocol (EAP) to peap, the inner authentication protocol to mschapv2, and the user name:

    # nmcli connection modify wlp1s0 wireless-security.key-mgmt wpa-eap 802-1x.eap peap 802-1x.phase2-auth mschapv2 802-1x.identity user_name

    Note that you must set the wireless-security.key-mgmt, 802-1x.eap, 802-1x.phase2-auth, and 802-1x.identity parameters in a single command.

  2. Optionally, store the password in the configuration:

    # nmcli connection modify wlp1s0 802-1x.password password
    Important

    By default, NetworkManager stores the password in plain text in the /etc/sysconfig/network-scripts/keys-connection_name file, which is readable only by the root user. However, plain text passwords in a configuration file can be a security risk.

    To increase the security, set the 802-1x.password-flags parameter to 0x1. With this setting, on servers with the GNOME desktop environment or the nm-applet running, NetworkManager retrieves the password from these services. In other cases, NetworkManager prompts for the password.

  3. If the client needs to verify the certificate of the authenticator, set the 802-1x.ca-cert parameter in the connection profile to the path of the CA certificate:

    # nmcli connection modify wlp1s0 802-1x.ca-cert /etc/pki/ca-trust/source/anchors/ca.crt
    Note

    For security reasons, Red Hat recommends the certificate of the authenticator to enable clients to validate the identity of the authenticator.

  4. Activate the connection profile:

    # nmcli connection up wlp1s0

Verification

  • Access resources on the network that require network authentication.

Additional resources

11.9. Manually setting the wireless regulatory domain

On RHEL, a udev rule executes the setregdomain utility to set the wireless regulatory domain. The utility then provides this information to the kernel.

By default, setregdomain attempts to determine the country code automatically. If this fails, the wireless regulatory domain setting might be wrong. To work around this problem, you can manually set the country code.

Important

Manually setting the regulatory domain disables the automatic detection. Therefore, if you later use the computer in a different country, the previously configured setting might no longer be correct. In this case, remove the /etc/sysconfig/regdomain file to switch back to automatic detection or use this procedure to manually update the regulatory domain setting again.

Procedure

  1. Optional: Display the current regulatory domain settings:

    # iw reg get
    global
    country US: DFS-FCC
    ...
  2. Create the /etc/sysconfig/regdomain file with the following content:

    COUNTRY=<country_code>

    Set the COUNTRY variable to an ISO 3166-1 alpha2 country code, such as DE for Germany or US for the United States of America.

  3. Set the regulatory domain:

    # setregdomain

Verification

  • Display the regulatory domain settings:

    # iw reg get
    global
    country DE: DFS-ETSI
    ...

Additional resources

Chapter 12. Configuring RHEL as a wifi access point

On a host with a wifi device, you can use NetworkManager to configure this host as an access point. Wireless clients can then use the access point to connect to services on the RHEL host or in the network.

When you configure an access point, NetworkManager automatically:

  • Configures the dnsmasq service to provide DHCP and DNS services for clients
  • Enables IP forwarding
  • Adds nftables firewall rules to masquerade traffic from the wifi device and configures IP forwarding

12.1. Identifying whether a wifi device supports the access point mode

To use a wifi device as an access point, the device must support this feature. You can use the nmcli utility to identify if the hardware supports access point mode.

Prerequisites

  • A wifi device is installed on the host.

Procedure

  1. List the wifi devices to identify the one that should provide the access point:

    # nmcli device status | grep wifi
    wlp0s20f3    wifi   disconnected    --
  2. Verify that the device supports the access point mode:

    # nmcli -f WIFI-PROPERTIES.AP device show wlp0s20f3
    WIFI-PROPERTIES.AP:     yes

12.2. Configuring RHEL as a WPA2 or WPA3 Personal access point

Wi-Fi Protected Access 2 (WPA2) and Wi-Fi Protected Access 3 (WPA3) Personal provide secure authentication methods in wireless networks. Users can connect to the access point using a pre-shared key (PSK).

Prerequisites

  • The wifi device supports running in access point mode.
  • The wifi device is not in use.
  • The host has internet access.

Procedure

  1. Install the dnsmasq and NetworkManager-wifi packages:

    # dnf install dnsmasq NetworkManager-wifi

    NetworkManager uses the dnsmasq service to provide DHCP and DNS services to clients of the access point.

  2. Create the initial access point configuration:

    # nmcli device wifi hotspot ifname wlp0s20f3 con-name Example-Hotspot ssid Example-Hotspot password "password"

    This command creates a connection profile for an access point on the wlp0s20f3 device that provides WPA2 and WPA3 Personal authentication. The name of the wireless network, the Service Set Identifier (SSID), is Example-Hotspot and uses the pre-shared key password.

  3. Optional: Configure the access point to support only WPA3:

    # nmcli connection modify Example-Hotspot 802-11-wireless-security.key-mgmt sae
  4. By default, NetworkManager uses the IP address 10.42.0.1 for the wifi device and assigns IP addresses from the remaining 10.42.0.0/24 subnet to clients. To configure a different subnet and IP address, enter:

    # nmcli connection modify Example-Hotspot ipv4.addresses 192.0.2.254/24

    The IP address you set, in this case 192.0.2.254, is the one that NetworkManager assigns to the wifi device. Clients will use this IP address as default gateway and DNS server.

  5. Activate the connection profile:

    # nmcli connection up Example-Hotspot

Verification

  1. On the server:

    1. Verify that NetworkManager started the dnsmasq service and that the service listens on port 67 (DHCP) and 53 (DNS):

      # ss -tulpn | egrep ":53|:67"
      udp   UNCONN 0  0   10.42.0.1:53    0.0.0.0:*    users:(("dnsmasq",pid=55905,fd=6))
      udp   UNCONN 0  0     0.0.0.0:67    0.0.0.0:*    users:(("dnsmasq",pid=55905,fd=4))
      tcp   LISTEN 0  32  10.42.0.1:53    0.0.0.0:*    users:(("dnsmasq",pid=55905,fd=7))
    2. Display the nftables rule set to ensure that NetworkManager enabled forwarding and masquerading for traffic from the 10.42.0.0/24 subnet:

      # nft list ruleset
      table ip nm-shared-wlp0s20f3 {
          chain nat_postrouting {
              type nat hook postrouting priority srcnat; policy accept;
              ip saddr 10.42.0.0/24 ip daddr != 10.42.0.0/24 masquerade
          }
      
          chain filter_forward {
              type filter hook forward priority filter; policy accept;
              ip daddr 10.42.0.0/24 oifname "wlp0s20f3" ct state { established, related } accept
              ip saddr 10.42.0.0/24 iifname "wlp0s20f3" accept
              iifname "wlp0s20f3" oifname "wlp0s20f3" accept
              iifname "wlp0s20f3" reject
              oifname "wlp0s20f3" reject
          }
      }
  2. On a client with a wifi adapter:

    1. Display the list of available networks:

      # nmcli device wifi
      IN-USE  BSSID              SSID             MODE   CHAN  RATE      SIGNAL  BARS  SECURITY
              00:53:00:88:29:04  Example-Hotspot  Infra  11    130 Mbit/s  62      ▂▄▆_  WPA3
      ...
    2. Connect to the Example-Hotspot wireless network. See Managing Wi-Fi connections.
    3. Ping a host on the remote network or the internet to verify that the connection works:

      # ping -c 3 www.redhat.com

Additional resources

Chapter 13. Changing a hostname

The hostname of a system is the name on the system itself. You can set the name when you install RHEL, and you can change it afterwards.

13.1. Changing a hostname using nmcli

You can use the nmcli utility to update the system hostname. Note that other utilities might use a different term, such as static or persistent hostname.

Procedure

  1. Optional: Display the current hostname setting:

    # nmcli general hostname
    old-hostname.example.com
  2. Set the new hostname:

    # nmcli general hostname new-hostname.example.com
  3. NetworkManager automatically restarts the systemd-hostnamed to activate the new name. However, the following manual actions can be required if you do not want to reboot the host:

    1. Restart all services that only read the hostname when the service starts:

      # systemctl restart <service_name>
    2. Active shell users must re-login for the changes to take effect.

Verification

  • Display the hostname:

    # nmcli general hostname
    new-hostname.example.com

13.2. Changing a hostname using hostnamectl

You can use the hostnamectl utility to update the hostname. By default, this utility sets the following hostname types:

  • Static hostname: Stored in the /etc/hostname file. Typically, services use this name as the hostname.
  • Pretty hostname: A descriptive name, such as Proxy server in data center A.
  • Transient hostname: A fall-back value that is typically received from the network configuration.

Procedure

  1. Optional: Display the current hostname setting:

    # hostnamectl status --static
    old-hostname.example.com
  2. Set the new hostname:

    # hostnamectl set-hostname new-hostname.example.com

    This command sets the static, pretty, and transient hostname to the new value. To set only a specific type, pass the --static, --pretty, or --transient option to the command.

  3. The hostnamectl utility automatically restarts the systemd-hostnamed to activate the new name. However, the following manual actions can be required if you do not want to reboot the host:

    1. Restart all services that only read the hostname when the service starts:

      # systemctl restart <service_name>
    2. Active shell users must re-login for the changes to take effect.

Verification

  • Display the hostname:

    # hostnamectl status --static
    new-hostname.example.com

Additional resources

  • hostnamectl(1)
  • systemd-hostnamed.service(8)

Chapter 14. Mirroring a network interface by using nmcli

Network administrators can use port mirroring to replicate inbound and outbound network traffic being communicated from one network device to another. Mirroring traffic of an interface can be helpful in the following situations:

  • To debug networking issues and tune the network flow
  • To inspect and analyze the network traffic
  • To detect an intrusion

Prerequisites

  • A network interface to mirror the network traffic to.

Procedure

  1. Add a network connection profile that you want to mirror the network traffic from:

    # nmcli connection add type ethernet ifname enp1s0 con-name enp1s0 autoconnect no
  2. Attach a prio qdisc to enp1s0 for the egress (outgoing) traffic with the 10: handle:

    # nmcli connection modify enp1s0 +tc.qdisc "root prio handle 10:"

    The prio qdisc attached without children allows attaching filters.

  3. Add a qdisc for the ingress traffic, with the ffff: handle:

    # nmcli connection modify enp1s0 +tc.qdisc "ingress handle ffff:"
  4. Add the following filters to match packets on the ingress and egress qdiscs, and to mirror them to enp7s0:

    # nmcli connection modify enp1s0 +tc.tfilter "parent ffff: matchall action mirred egress mirror dev enp7s0"
    
    # nmcli connection modify enp1s0 +tc.tfilter "parent 10: matchall action mirred egress mirror dev enp7s0"

    The matchall filter matches all packets, and the mirred action redirects packets to destination.

  5. Activate the connection:

    # nmcli connection up enp1s0

Verification

  1. Install the tcpdump utility:

    # dnf install tcpdump
  2. Display the traffic mirrored on the target device (enp7s0):

    # tcpdump -i enp7s0

Chapter 15. Configuring NetworkManager to ignore certain devices

By default, NetworkManager manages all devices. To ignore certain devices, you can configure NetworkManager by setting as unmanaged.

15.1. Configuring the loopback interface by using nmcli

By default, NetworkManager does not manage the loopback (lo) interface. After creating a connection profile for the lo interface, you can configure this device by using NetworkManager. Some of the examples are as follows:

  • Assign additional IP addresses to the lo interface
  • Define DNS addresses
  • Change the Maximum Transmission Unit (MTU) size of the lo interface

Procedure

  1. Create a new connection of type loopback:

    # nmcli connection add con-name example-loopback type loopback
  2. Configure custom connection settings, for example:

    1. To assign an additional IP address to the interface, enter:

      # nmcli connection modify example-loopback +ipv4.addresses 192.0.2.1/24
      Note

      NetworkManager manages the lo interface by always assigning the IP addresses 127.0.0.1 and ::1 that are persistent across the reboots. You can not override 127.0.0.1 and ::1. However, you can assign additional IP addresses to the interface.

    2. To set a custom Maximum Transmission Unit (MTU), enter:

      # nmcli con mod example-loopback loopback.mtu 16384
    3. To set an IP address to your DNS server, enter:

      # nmcli connection modify example-loopback ipv4.dns 192.0.2.0

      If you set a DNS server in the loopback connection profile, this entry is always available in the /etc/resolv.conf file. The DNS server entry remains independent of whether or not the host roams between different networks.

  3. Activate the connection:

    # nmcli connection up example-loopback

Verification

  1. Display the settings of the lo interface:

    # ip address show lo
    
    1: lo: <LOOPBACK,UP,LOWER_UP> mtu 16384 qdisc noqueue state UNKNOWN group default qlen 1000
    
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00 inet 127.0.0.1/8 scope host lo valid_lft forever preferred_lft forever inet 192.0.2.1/24 brd 192.0.2.255 scope global lo valid_lft forever preferred_lft forever
    
    inet6 ::1/128 scope host
    valid_lft forever preferred_lft forever
  2. Verify the DNS address:

    # cat /etc/resolv.conf
    
    ...
    nameserver 192.0.2.0
    ...

15.2. Permanently configuring a device as unmanaged in NetworkManager

You can permanently configure devices as unmanaged based on several criteria, such as the interface name, MAC address, or device type.

To temporarily configure network devices as unmanaged, see Temporarily configuring a device as unmanaged in NetworkManager.

Procedure

  1. Optional: Display the list of devices to identify the device or MAC address you want to set as unmanaged:

    # ip link show
    ...
    2: enp1s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP mode DEFAULT group default qlen 1000
        link/ether 52:54:00:74:79:56 brd ff:ff:ff:ff:ff:ff
    ...
  2. Create the /etc/NetworkManager/conf.d/99-unmanaged-devices.conf file with the following content:

    • To configure a specific interface as unmanaged, add:

      [keyfile]
      unmanaged-devices=interface-name:enp1s0
    • To configure a device with a specific MAC address as unmanaged, add:

      [keyfile]
      unmanaged-devices=mac:52:54:00:74:79:56
    • To configure all devices of a specific type as unmanaged, add:

      [keyfile]
      unmanaged-devices=type:ethernet
    • To set multiple devices as unmanaged, separate the entries in the unmanaged-devices parameter with a semicolon, for example:

      [keyfile]
      unmanaged-devices=interface-name:enp1s0;interface-name:enp7s0
  3. Reload the NetworkManager service:

    # systemctl reload NetworkManager

Verification

  • Display the list of devices:

    # nmcli device status
    DEVICE  TYPE      STATE      CONNECTION
    enp1s0  ethernet  unmanaged  --
    ...

    The unmanaged state next to the enp1s0 device indicates that NetworkManager does not manage this device.

Troubleshooting

  • If the device is not shown as unmanaged, display the NetworkManager configuration:

    # NetworkManager --print-config
    ...
    [keyfile]
    unmanaged-devices=interface-name:enp1s0
    ...

    If the output does not match the settings that you configured, ensure that no configuration file with a higher priority overrides your settings. For details about how NetworkManager merges multiple configuration files, see the NetworkManager.conf(5) man page.

15.3. Temporarily configuring a device as unmanaged in NetworkManager

You can temporarily configure devices as unmanaged.

Use this method, for example, for testing purposes. To permanently configure network devices as unmanaged, see Permanently configuring a device as unmanaged in NetworkManager.

Procedure

  1. Optional: Display the list of devices to identify the device you want to set as unmanaged:

    # nmcli device status
    DEVICE  TYPE      STATE         CONNECTION
    enp1s0  ethernet  disconnected  --
    ...
  2. Set the enp1s0 device to the unmanaged state:

    # nmcli device set enp1s0 managed no

Verification

  • Display the list of devices:

    # nmcli device status
    DEVICE  TYPE      STATE      CONNECTION
    enp1s0  ethernet  unmanaged  --
    ...

    The unmanaged state next to the enp1s0 device indicates that NetworkManager does not manage this device.

Additional resources

  • NetworkManager.conf(5) man page

Chapter 16. Configuring network devices to accept traffic from all MAC addresses

Network devices usually intercept and read packets that their controller is programmed to receive. You can configure the network devices to accept traffic from all MAC addresses in a virtual switch or at the port group level.

You can use this network mode to:

  • Diagnose network connectivity issues
  • Monitor network activity for security reasons
  • Intercept private data-in-transit or intrusion in the network

You can enable this mode for any kind of network device, except InfiniBand.

16.1. Temporarily configuring a device to accept all traffic

You can use the ip utility to temporary configure a network device to accept all traffic regardless of the MAC addresses.

Procedure

  1. Optional: Display the network interfaces to identify the one for which you want to receive all traffic:

    # ip address show
    1: enp1s0: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc fq_codel state DOWN group default qlen 1000
        link/ether 98:fa:9b:a4:34:09 brd ff:ff:ff:ff:ff:ff
    ...
  2. Modify the device to enable or disable this property:

    • To enable the accept-all-mac-addresses mode for enp1s0:

      # ip link set enp1s0 promisc on
    • To disable the accept-all-mac-addresses mode for enp1s0:

      # ip link set enp1s0 promisc off

Verification

  • Verify that the accept-all-mac-addresses mode is enabled:

    # ip link show enp1s0
    1: enp1s0: <NO-CARRIER,BROADCAST,MULTICAST,PROMISC,UP> mtu 1500 qdisc fq_codel state DOWN mode DEFAULT group default qlen 1000
        link/ether 98:fa:9b:a4:34:09 brd ff:ff:ff:ff:ff:ff

    The PROMISC flag in the device description indicates that the mode is enabled.

16.2. Permanently configuring a network device to accept all traffic using nmcli

You can use the nmcli utility to permanently configure a network device to accept all traffic regardless of the MAC addresses.

Procedure

  1. Optional: Display the network interfaces to identify the one for which you want to receive all traffic:

    # ip address show
    1: enp1s0: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc fq_codel state DOWN group default qlen 1000
        link/ether 98:fa:9b:a4:34:09 brd ff:ff:ff:ff:ff:ff
    ...

    You can create a new connection, if you do not have any.

  2. Modify the network device to enable or disable this property.

    • To enable the ethernet.accept-all-mac-addresses mode for enp1s0:

      # nmcli connection modify enp1s0 ethernet.accept-all-mac-addresses yes
    • To disable the accept-all-mac-addresses mode for enp1s0:

      # nmcli connection modify enp1s0 ethernet.accept-all-mac-addresses no
  3. Apply the changes, reactivate the connection:

    # nmcli connection up enp1s0

Verification

  • Verify that the ethernet.accept-all-mac-addresses mode is enabled:

    # nmcli connection show enp1s0
    ...
    802-3-ethernet.accept-all-mac-addresses:1     (true)

    The 802-3-ethernet.accept-all-mac-addresses: true indicates that the mode is enabled.

16.3. Permanently configuring a network device to accept all traffic using nmstatectl

Use the nmstatectl utility to configure a device to accept all traffic regardless of the MAC addresses through the Nmstate API. The Nmstate API ensures that, after setting the configuration, the result matches the configuration file. If anything fails, nmstatectl automatically rolls back the changes to avoid leaving the system in an incorrect state.

Prerequisites

  • The nmstate package is installed.
  • The enp1s0.yml file that you used to configure the device is available.

Procedure

  1. Edit the existing enp1s0.yml file for the enp1s0 connection and add the following content to it:

    ---
    interfaces:
      - name: enp1s0
        type: ethernet
        state: up
        accept -all-mac-address: true

    These settings configure the enp1s0 device to accept all traffic.

  2. Apply the network settings:

    # nmstatectl apply ~/enp1s0.yml

Verification

  • Verify that the 802-3-ethernet.accept-all-mac-addresses mode is enabled:

    # nmstatectl show enp1s0
    interfaces:
      - name: enp1s0
        type: ethernet
        state: up
        accept-all-mac-addresses:     true
    ...

    The 802-3-ethernet.accept-all-mac-addresses: true indicates that the mode is enabled.

Additional resources

  • nmstatectl(8) man page
  • /usr/share/doc/nmstate/examples/ directory

Chapter 17. Setting up an 802.1x network authentication service for LAN clients by using hostapd with FreeRADIUS backend

The IEEE 802.1X standard defines secure authentication and authorization methods to protect networks from unauthorized clients. By using the hostapd service and FreeRADIUS, you can provide network access control (NAC) in your network.

In this documentation, the RHEL host acts as a bridge to connect different clients with an existing network. However, the RHEL host grants only authenticated clients access to the network.

rhel authenticator 802 1x

17.1. Prerequisites

  • A clean installation of FreeRADIUS.

    If the freeradius package is already installed, remove the /etc/raddb/ directory, uninstall and then install the package again. Do not reinstall the package by using the dnf reinstall command, because the permissions and symbolic links in the /etc/raddb/ directory are then different.

17.2. Setting up the bridge on the authenticator

A network bridge is a link-layer device which forwards traffic between hosts and networks based on a table of MAC addresses. If you set up RHEL as an 802.1X authenticator, add both the interfaces on which to perform authentication and the LAN interface to the bridge.

Prerequisites

  • The server has multiple Ethernet interfaces.

Procedure

  1. Create the bridge interface:

    # nmcli connection add type bridge con-name br0 ifname br0
  2. Assign the Ethernet interfaces to the bridge:

    # nmcli connection add type ethernet slave-type bridge con-name br0-port1 ifname enp1s0 master br0
    # nmcli connection add type ethernet slave-type bridge con-name br0-port2 ifname enp7s0 master br0
    # nmcli connection add type ethernet slave-type bridge con-name br0-port3 ifname enp8s0 master br0
    # nmcli connection add type ethernet slave-type bridge con-name br0-port4 ifname enp9s0 master br0
  3. Enable the bridge to forward extensible authentication protocol over LAN (EAPOL) packets:

    # nmcli connection modify br0 group-forward-mask 8
  4. Configure the connection to automatically activate the ports:

    # nmcli connection modify br0 connection.autoconnect-slaves 1
  5. Activate the connection:

    # nmcli connection up br0

Verification

  1. Display the link status of Ethernet devices that are ports of a specific bridge:

    # ip link show master br0
    3: enp1s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel master br0 state UP mode DEFAULT group default qlen 1000
        link/ether 52:54:00:62:61:0e brd ff:ff:ff:ff:ff:ff
    ...
  2. Verify if forwarding of EAPOL packets is enabled on the br0 device:

    # cat /sys/class/net/br0/bridge/group_fwd_mask
    0x8

    If the command returns 0x8, forwarding is enabled.

Additional resources

  • nm-settings(5) man page

17.3. Certificate requirements by FreeRADIUS

For a secure FreeRADIUS service, you require TLS certificates for different purposes:

  • A TLS server certificate for encrypted connections to the server. Use a trusted certificate authority (CA) to issue the certificate.

    The server certificate requires the extended key usage (EKU) field set to TLS Web Server Authentication.

  • Client certificates issued by the same CA for extended authentication protocol transport layer security (EAP-TLS). EAP-TLS provides certificate-based authentication and is enabled by default.

    The client certificates require their EKU field set to TLS Web Client Authentication.

Warning

To secure connection, use your company’s CA or create your own CA to issue certificates for FreeRADIUS. If you use a public CA, you allow it to authenticate users and issue client certificates for EAP-TLS.

17.4. Creating a set of certificates on a FreeRADIUS server for testing purposes

For testing purposes, the freeradius package installs scripts and configuration files in the /etc/raddb/certs/ directory to create your own certificate authority (CA) and issue certificates.

Important

If you use the default configuration, certificates generated by these scripts expire after 60 days and keys use an insecure password ("whatever"). However, you can customize the CA, server, and client configuration.

After you perform the procedure, the following files, which you require later in this documentation, are created:

  • /etc/raddb/certs/ca.pem: CA certificate
  • /etc/raddb/certs/server.key: Private key of the server certificate
  • /etc/raddb/certs/server.pem: Server certificate
  • /etc/raddb/certs/client.key: Private key of the client certificate
  • /etc/raddb/certs/client.pem: Client certificate

Prerequisites

  • You installed the freeradius package.

Procedure

  1. Change into the /etc/raddb/certs/ directory:

    # cd /etc/raddb/certs/
  2. Optional: Customize the CA configuration in the /etc/raddb/certs/ca.cnf file:

    ...
    [ req ]
    default_bits            = 2048
    input_password          = ca_password
    output_password         = ca_password
    ...
    [certificate_authority]
    countryName             = US
    stateOrProvinceName     = North Carolina
    localityName            = Raleigh
    organizationName        = Example Inc.
    emailAddress            = admin@example.org
    commonName              = "Example Certificate Authority"
    ...
  3. Optional: Customize the server configuration in the /etc/raddb/certs/server.cnf file::

    ...
    [ CA_default ]
    default_days            = 730
    ...
    [ req ]
    distinguished_name      = server
    default_bits            = 2048
    input_password          = key_password
    output_password         = key_password
    ...
    [server]
    countryName             = US
    stateOrProvinceName     = North Carolina
    localityName            = Raleigh
    organizationName        = Example Inc.
    emailAddress            = admin@example.org
    commonName              = "Example Server Certificate"
    ...
  4. Optional: Customize the client configuration in the /etc/raddb/certs/client.cnf file::

    ...
    [ CA_default ]
    default_days            = 365
    ...
    [ req ]
    distinguished_name      = client
    default_bits            = 2048
    input_password          = password_on_private_key
    output_password         = password_on_private_key
    ...
    [client]
    countryName             = US
    stateOrProvinceName     = North Carolina
    localityName            = Raleigh
    organizationName        = Example Inc.
    emailAddress            = user@example.org
    commonName              = user@example.org
    ...
  5. Create the certificates:

    # make all
  6. Change the group on the /etc/raddb/certs/server.pem file to radiusd:

    # chgrp radiusd /etc/raddb/certs/server.pem

Additional resources

  • /etc/raddb/certs/README.md

17.5. Configuring FreeRADIUS to authenticate network clients securely by using EAP

FreeRADIUS supports different methods of the Extensible authentication protocol (EAP). However, for a secure network, configure FreeRADIUS to support only the following secure EAP authentication methods:

  • EAP-TLS (transport layer security) uses a secure TLS connection to authenticate clients by using certificates. To use EAP-TLS, you need TLS client certificates for each network client and a server certificate for the server. Note that the same certificate authority (CA) must have issued the certificates. Always use your own CA to create certificates, because all client certificates issued by the CA you use can authenticate to your FreeRADIUS server.
  • EAP-TTLS (tunneled transport layer security) uses a secure TLS connection and authenticates clients by using mechanisms, such as password authentication protocol (PAP) or challenge handshake authentication protocol (CHAP). To use EAP-TTLS, you need a TLS server certificate.
  • EAP-PEAP (protected extensible authentication protocol) uses a secure TLS connection as the outer authentication protocol to set up the tunnel. The authenticator authenticates the certificate of the RADIUS server. Afterwards, the supplicant authenticates through the encrypted tunnel by using Microsoft challenge handshake authentication protocol version 2 (MS-CHAPv2) or other methods.
Note

The default FreeRADIUS configuration files serve as documentation and describe all parameters and directives. If you want to disable certain features, comment them out instead of removing the corresponding parts in the configuration files. This enables you to preserve the structure of the configuration files and the included documentation.

Prerequisites

  • You installed the freeradius package.
  • The configuration files in the /etc/raddb/ directory are unchanged and as provided by the freeradius package.
  • The following files exist on the server:

    • TLS private key of the FreeRADIUS host: /etc/raddb/certs/server.key
    • TLS server certificate of the FreeRADIUS host: /etc/raddb/certs/server.pem
    • TLS CA certificate: /etc/raddb/certs/ca.pem

    If you store the files in a different location or if they have different names, set the private_key_file, certificate_file, and ca_file parameters in the /etc/raddb/mods-available/eap file accordingly.

Procedure

  1. If the /etc/raddb/certs/dh with Diffie-Hellman (DH) parameters does not exist, create one. For example, to create a DH file with a 2048 bits prime, enter:

    # openssl dhparam -out /etc/raddb/certs/dh 2048

    For security reasons, do not use a DH file with less than a 2048 bits prime. Depending on the number of bits, the creation of the file can take several minutes.

  2. Set secure permissions on the TLS private key, server certificate, CA certificate, and the file with DH parameters:

    # chmod 640 /etc/raddb/certs/server.key /etc/raddb/certs/server.pem /etc/raddb/certs/ca.pem /etc/raddb/certs/dh
    # chown root:radiusd /etc/raddb/certs/server.key /etc/raddb/certs/server.pem /etc/raddb/certs/ca.pem /etc/raddb/certs/dh
  3. Edit the /etc/raddb/mods-available/eap file:

    1. Set the password of the private key in the private_key_password parameter:

      eap {
          ...
          tls-config tls-common {
              ...
              private_key_password = key_password
              ...
          }
      }
    2. Depending on your environment, set the default_eap_type parameter in the eap directive to your primary EAP type you use:

      eap {
          ...
          default_eap_type = ttls
          ...
      }

      For a secure environment, use only ttls, tls, or peap.

    3. Comment out the md5 directives to disable the insecure EAP-MD5 authentication method:

      eap {
          ...
          # md5 {
          # }
          ...
      }

      Note that, in the default configuration file, other insecure EAP authentication methods are commented out by default.

  4. Edit the /etc/raddb/sites-available/default file, and comment out all authentication methods other than eap:

    authenticate {
        ...
        # Auth-Type PAP {
        #     pap
        # }
    
        # Auth-Type CHAP {
        #     chap
        # }
    
        # Auth-Type MS-CHAP {
        #     mschap
        # }
    
        # mschap
    
        # digest
        ...
    }

    This leaves only EAP enabled and disables plain-text authentication methods.

  5. Edit the /etc/raddb/clients.conf file:

    1. Set a secure password in the localhost and localhost_ipv6 client directives:

      client localhost {
          ipaddr = 127.0.0.1
          ...
          secret = client_password
          ...
      }
      
      client localhost_ipv6 {
          ipv6addr = ::1
          secret = client_password
      }
    2. If RADIUS clients, such as network authenticators, on remote hosts should be able to access the FreeRADIUS service, add corresponding client directives for them:

      client hostapd.example.org {
          ipaddr = 192.0.2.2/32
          secret = client_password
      }

      The ipaddr parameter accepts IPv4 and IPv6 addresses, and you can use the optional classless inter-domain routing (CIDR) notation to specify ranges. However, you can set only one value in this parameter. For example, to grant access to an IPv4 and IPv6 address, add two client directives.

      Use a descriptive name for the client directive, such as a hostname or a word that describes where the IP range is used.

  6. If you want to use EAP-TTLS or EAP-PEAP, add the users to the /etc/raddb/users file:

    example_user        Cleartext-Password := "user_password"

    For users who should use certificate-based authentication (EAP-TLS), do not add any entry.

  7. Verify the configuration files:

    # radiusd -XC
    ...
    Configuration appears to be OK
  8. Enable and start the radiusd service:

    # systemctl enable --now radiusd

Troubleshooting

  1. Stop the radiusd service:

    # systemctl stop radiusd
  2. Start the service in debug mode:

    # radiusd -X
    ...
    Ready to process requests
  3. Perform authentication tests on the FreeRADIUS host, as referenced in the Verification section.

Next steps

  • Disable no longer required authentication methods and other features you do not use.

17.6. Configuring hostapd as an authenticator in a wired network

The host access point daemon (hostapd) service can act as an authenticator in a wired network to provide 802.1X authentication. For this, the hostapd service requires a RADIUS server that authenticates the clients.

The hostapd service provides an integrated RADIUS server. However, use the integrated RADIUS server only for testing purposes. For production environments, use FreeRADIUS server, which supports additional features, such as different authentication methods and access control.

Important

The hostapd service does not interact with the traffic plane. The service acts only as an authenticator. For example, use a script or service that uses the hostapd control interface to allow or deny traffic based on the result of authentication events.

Prerequisites

  • You installed the hostapd package.
  • The FreeRADIUS server has been configured, and it is ready to authenticate clients.

Procedure

  1. Create the /etc/hostapd/hostapd.conf file with the following content:

    # General settings of hostapd
    # ===========================
    
    # Control interface settings
    ctrl_interface=/var/run/hostapd
    ctrl_interface_group=wheel
    
    # Enable logging for all modules
    logger_syslog=-1
    logger_stdout=-1
    
    # Log level
    logger_syslog_level=2
    logger_stdout_level=2
    
    
    # Wired 802.1X authentication
    # ===========================
    
    # Driver interface type
    driver=wired
    
    # Enable IEEE 802.1X authorization
    ieee8021x=1
    
    # Use port access entry (PAE) group address
    # (01:80:c2:00:00:03) when sending EAPOL frames
    use_pae_group_addr=1
    
    
    # Network interface for authentication requests
    interface=br0
    
    
    # RADIUS client configuration
    # ===========================
    
    # Local IP address used as NAS-IP-Address
    own_ip_addr=192.0.2.2
    
    # Unique NAS-Identifier within scope of RADIUS server
    nas_identifier=hostapd.example.org
    
    # RADIUS authentication server
    auth_server_addr=192.0.2.1
    auth_server_port=1812
    auth_server_shared_secret=client_password
    
    # RADIUS accounting server
    acct_server_addr=192.0.2.1
    acct_server_port=1813
    acct_server_shared_secret=client_password

    For further details about the parameters used in this configuration, see their descriptions in the /usr/share/doc/hostapd/hostapd.conf example configuration file.

  2. Enable and start the hostapd service:

    # systemctl enable --now hostapd

Troubleshooting

  1. Stop the hostapd service:

    # systemctl stop hostapd
  2. Start the service in debug mode:

    # hostapd -d /etc/hostapd/hostapd.conf
  3. Perform authentication tests on the FreeRADIUS host, as referenced in the Verification section.

Additional resources

  • hostapd.conf(5) man page
  • /usr/share/doc/hostapd/hostapd.conf file

17.7. Testing EAP-TTLS authentication against a FreeRADIUS server or authenticator

To test if authentication by using extensible authentication protocol (EAP) over tunneled transport layer security (EAP-TTLS) works as expected, run this procedure:

  • After you set up the FreeRADIUS server
  • After you set up the hostapd service as an authenticator for 802.1X network authentication.

The output of the test utilities used in this procedure provide additional information about the EAP communication and help you to debug problems.

Prerequisites

  • When you want to authenticate to:

    • A FreeRADIUS server:

      • The eapol_test utility, provided by the hostapd package, is installed.
      • The client, on which you run this procedure, has been authorized in the FreeRADIUS server’s client databases.
    • An authenticator, the wpa_supplicant utility, provided by the same-named package, is installed.
  • You stored the certificate authority (CA) certificate in the /etc/pki/tls/certs/ca.pem file.

Procedure

  1. Create the /etc/wpa_supplicant/wpa_supplicant-TTLS.conf file with the following content:

    ap_scan=0
    
    network={
        eap=TTLS
        eapol_flags=0
        key_mgmt=IEEE8021X
    
        # Anonymous identity (sent in unencrypted phase 1)
        # Can be any string
        anonymous_identity="anonymous"
    
        # Inner authentication (sent in TLS-encrypted phase 2)
        phase2="auth=PAP"
        identity="example_user"
        password="user_password"
    
        # CA certificate to validate the RADIUS server's identity
        ca_cert="/etc/pki/tls/certs/ca.pem"
    }
  2. To authenticate to:

    • A FreeRADIUS server, enter:

      # eapol_test -c /etc/wpa_supplicant/wpa_supplicant-TTLS.conf -a 192.0.2.1 -s client_password
      ...
      EAP: Status notification: remote certificate verification (param=success)
      ...
      CTRL-EVENT-EAP-SUCCESS EAP authentication completed successfully
      ...
      SUCCESS

      The -a option defines the IP address of the FreeRADIUS server, and the -s option specifies the password for the host on which you run the command in the FreeRADIUS server’s client configuration.

    • An authenticator, enter:

      # wpa_supplicant -c /etc/wpa_supplicant/wpa_supplicant-TTLS.conf -D wired -i enp0s31f6
      ...
      enp0s31f6: CTRL-EVENT-EAP-SUCCESS EAP authentication completed successfully
      ...

      The -i option specifies the network interface name on which wpa_supplicant sends out extended authentication protocol over LAN (EAPOL) packets.

      For more debugging information, pass the -d option to the command.

Additional resources

  • /usr/share/doc/wpa_supplicant/wpa_supplicant.conf file

17.8. Testing EAP-TLS authentication against a FreeRADIUS server or authenticator

To test if authentication by using extensible authentication protocol (EAP) transport layer security (EAP-TLS) works as expected, run this procedure:

  • After you set up the FreeRADIUS server
  • After you set up the hostapd service as an authenticator for 802.1X network authentication.

The output of the test utilities used in this procedure provide additional information about the EAP communication and help you to debug problems.

Prerequisites

  • When you want to authenticate to:

    • A FreeRADIUS server:

      • The eapol_test utility, provided by the hostapd package, is installed.
      • The client, on which you run this procedure, has been authorized in the FreeRADIUS server’s client databases.
    • An authenticator, the wpa_supplicant utility, provided by the same-named package, is installed.
  • You stored the certificate authority (CA) certificate in the /etc/pki/tls/certs/ca.pem file.
  • The CA that issued the client certificate is the same that issued the server certificate of the FreeRADIUS server.
  • You stored the client certificate in the /etc/pki/tls/certs/client.pem file.
  • You stored the private key of the client in the /etc/pki/tls/private/client.key

Procedure

  1. Create the /etc/wpa_supplicant/wpa_supplicant-TLS.conf file with the following content:

    ap_scan=0
    
    network={
        eap=TLS
        eapol_flags=0
        key_mgmt=IEEE8021X
    
        identity="user@example.org"
        client_cert="/etc/pki/tls/certs/client.pem"
        private_key="/etc/pki/tls/private/client.key"
        private_key_passwd="password_on_private_key"
    
        # CA certificate to validate the RADIUS server's identity
        ca_cert="/etc/pki/tls/certs/ca.pem"
    }
  2. To authenticate to:

    • A FreeRADIUS server, enter:

      # eapol_test -c /etc/wpa_supplicant/wpa_supplicant-TLS.conf -a 192.0.2.1 -s client_password
      ...
      EAP: Status notification: remote certificate verification (param=success)
      ...
      CTRL-EVENT-EAP-SUCCESS EAP authentication completed successfully
      ...
      SUCCESS

      The -a option defines the IP address of the FreeRADIUS server, and the -s option specifies the password for the host on which you run the command in the FreeRADIUS server’s client configuration.

    • An authenticator, enter:

      # wpa_supplicant -c /etc/wpa_supplicant/wpa_supplicant-TLS.conf -D wired -i enp0s31f6
      ...
      enp0s31f6: CTRL-EVENT-EAP-SUCCESS EAP authentication completed successfully
      ...

      The -i option specifies the network interface name on which wpa_supplicant sends out extended authentication protocol over LAN (EAPOL) packets.

      For more debugging information, pass the -d option to the command.

Additional resources

  • /usr/share/doc/wpa_supplicant/wpa_supplicant.conf file

17.9. Blocking and allowing traffic based on hostapd authentication events

The hostapd service does not interact with the traffic plane. The service acts only as an authenticator. However, you can write a script to allow and deny traffic based on the result of authentication events.

Important

This procedure is not supported and is no enterprise-ready solution. It only demonstrates how to block or allow traffic by evaluating events retrieved by hostapd_cli.

When the 802-1x-tr-mgmt systemd service starts, RHEL blocks all traffic on the listen port of hostapd except extensible authentication protocol over LAN (EAPOL) packets and uses the hostapd_cli utility to connect to the hostapd control interface. The /usr/local/bin/802-1x-tr-mgmt script then evaluates events. Depending on the different events received by hostapd_cli, the script allows or blocks traffic for MAC addresses. Note that, when the 802-1x-tr-mgmt service stops, all traffic is automatically allowed again.

Perform this procedure on the hostapd server.

Prerequisites

  • The hostapd service has been configured, and the service is ready to authenticate clients.

Procedure

  1. Create the /usr/local/bin/802-1x-tr-mgmt file with the following content:

    #!/bin/sh
    
    if [ "x$1" == "xblock_all" ]
    then
    
        nft delete table bridge tr-mgmt-br0 2>/dev/null || true
        nft -f - << EOF
    table bridge tr-mgmt-br0 {
            set allowed_macs {
                    type ether_addr
            }
    
            chain accesscontrol {
                    ether saddr @allowed_macs accept
                    ether daddr @allowed_macs accept
                    drop
            }
    
            chain forward {
                    type filter hook forward priority 0; policy accept;
                    meta ibrname "br0" jump accesscontrol
            }
    }
    EOF
        echo "802-1x-tr-mgmt Blocking all traffic through br0. Traffic for given host will be allowed after 802.1x authentication"
    
    elif [ "x$1" == "xallow_all" ]
    then
    
        nft delete table bridge tr-mgmt-br0
        echo "802-1x-tr-mgmt Allowed all forwarding again"
    
    fi
    
    case ${2:-NOTANEVENT} in
    
        AP-STA-CONNECTED | CTRL-EVENT-EAP-SUCCESS | CTRL-EVENT-EAP-SUCCESS2)
            nft add element bridge tr-mgmt-br0 allowed_macs { $3 }
            echo "$1: Allowed traffic from $3"
            ;;
    
        AP-STA-DISCONNECTED | CTRL-EVENT-EAP-FAILURE)
            nft delete element bridge tr-mgmt-br0 allowed_macs { $3 }
            echo "802-1x-tr-mgmt $1: Denied traffic from $3"
            ;;
    
    esac
  2. Create the /etc/systemd/system/802-1x-tr-mgmt@.service systemd service file with the following content:

    [Unit]
    Description=Example 802.1x traffic management for hostapd
    After=hostapd.service
    After=sys-devices-virtual-net-%i.device
    
    [Service]
    Type=simple
    ExecStartPre=-/bin/sh -c '/usr/sbin/tc qdisc del dev %i ingress > /dev/null 2>&1'
    ExecStartPre=-/bin/sh -c '/usr/sbin/tc qdisc del dev %i clsact > /dev/null 2>&1'
    ExecStartPre=/usr/sbin/tc qdisc add dev %i clsact
    ExecStartPre=/usr/sbin/tc filter add dev %i ingress pref 10000 protocol 0x888e matchall action ok index 100
    ExecStartPre=/usr/sbin/tc filter add dev %i ingress pref 10001 protocol all matchall action drop index 101
    ExecStart=/usr/sbin/hostapd_cli -i %i -a /usr/local/bin/802-1x-tr-mgmt
    ExecStopPost=-/usr/sbin/tc qdisc del dev %i clsact
    
    [Install]
    WantedBy=multi-user.target
  3. Reload systemd:

    # systemctl daemon-reload
  4. Enable and start the 802-1x-tr-mgmt service with the interface name hostapd is listening on:

    # systemctl enable --now 802-1x-tr-mgmt@br0.service

Additional resources

  • systemd.service(5) man page

Chapter 18. Authenticating a RHEL client to the network by using the 802.1X standard with a certificate stored on the file system

Administrators frequently use port-based Network Access Control (NAC) based on the IEEE 802.1X standard to protect a network from unauthorized LAN and Wi-Fi clients. To enable a client to connect to such networks, you must configure 802.1X authentication on this clients.

18.1. Configuring 802.1X network authentication on an existing Ethernet connection by using nmcli

You can use the nmcli utility to configure an Ethernet connection with 802.1X network authentication on the command line.

Prerequisites

  • The network supports 802.1X network authentication.
  • The Ethernet connection profile exists in NetworkManager and has a valid IP configuration.
  • The following files required for TLS authentication exist on the client:

    • The client key stored is in the /etc/pki/tls/private/client.key file, and the file is owned and only readable by the root user.
    • The client certificate is stored in the /etc/pki/tls/certs/client.crt file.
    • The Certificate Authority (CA) certificate is stored in the /etc/pki/tls/certs/ca.crt file.
  • The wpa_supplicant package is installed.

Procedure

  1. Set the Extensible Authentication Protocol (EAP) to tls and the paths to the client certificate and key file:

    # nmcli connection modify enp1s0 802-1x.eap tls 802-1x.client-cert /etc/pki/tls/certs/client.crt 802-1x.private-key /etc/pki/tls/certs/certs/client.key

    Note that you must set the 802-1x.eap, 802-1x.client-cert, and 802-1x.private-key parameters in a single command.

  2. Set the path to the CA certificate:

    # nmcli connection modify enp1s0 802-1x.ca-cert /etc/pki/tls/certs/ca.crt
  3. Set the identity of the user used in the certificate:

    # nmcli connection modify enp1s0 802-1x.identity user@example.com
  4. Optionally, store the password in the configuration:

    # nmcli connection modify enp1s0 802-1x.private-key-password password
    Important

    By default, NetworkManager stores the password in clear text in the /etc/sysconfig/network-scripts/keys-connection_name file, that is readable only by the root user. However, clear text passwords in a configuration file can be a security risk.

    To increase the security, set the 802-1x.password-flags parameter to 0x1. With this setting, on servers with the GNOME desktop environment or the nm-applet running, NetworkManager retrieves the password from these services. In other cases, NetworkManager prompts for the password.

  5. Activate the connection profile:

    # nmcli connection up enp1s0

Verification

  • Access resources on the network that require network authentication.

Additional resources

18.2. Configuring a static Ethernet connection with 802.1X network authentication by using nmstatectl

Use the nmstatectl utility to configure an Ethernet connection with 802.1X network authentication through the Nmstate API. The Nmstate API ensures that, after setting the configuration, the result matches the configuration file. If anything fails, nmstatectl automatically rolls back the changes to avoid leaving the system in an incorrect state.

Note

The nmstate library only supports the TLS Extensible Authentication Protocol (EAP) method.

Prerequisites

  • The network supports 802.1X network authentication.
  • The managed node uses NetworkManager.
  • The following files required for TLS authentication exist on the client:

    • The client key stored is in the /etc/pki/tls/private/client.key file, and the file is owned and only readable by the root user.
    • The client certificate is stored in the /etc/pki/tls/certs/client.crt file.
    • The Certificate Authority (CA) certificate is stored in the /etc/pki/tls/certs/ca.crt file.

Procedure

  1. Create a YAML file, for example ~/create-ethernet-profile.yml, with the following content:

    ---
    interfaces:
    - name: enp1s0
      type: ethernet
      state: up
      ipv4:
        enabled: true
        address:
        - ip: 192.0.2.1
          prefix-length: 24
        dhcp: false
      ipv6:
        enabled: true
        address:
        - ip: 2001:db8:1::1
          prefix-length: 64
        autoconf: false
        dhcp: false
      802.1x:
        ca-cert: /etc/pki/tls/certs/ca.crt
        client-cert: /etc/pki/tls/certs/client.crt
        eap-methods:
          - tls
        identity: client.example.org
        private-key: /etc/pki/tls/private/client.key
        private-key-password: password
    routes:
      config:
      - destination: 0.0.0.0/0
        next-hop-address: 192.0.2.254
        next-hop-interface: enp1s0
      - destination: ::/0
        next-hop-address: 2001:db8:1::fffe
        next-hop-interface: enp1s0
    dns-resolver:
      config:
        search:
        - example.com
        server:
        - 192.0.2.200
        - 2001:db8:1::ffbb

    These settings define an Ethernet connection profile for the enp1s0 device with the following settings:

    • A static IPv4 address - 192.0.2.1 with a /24 subnet mask
    • A static IPv6 address - 2001:db8:1::1 with a /64 subnet mask
    • An IPv4 default gateway - 192.0.2.254
    • An IPv6 default gateway - 2001:db8:1::fffe
    • An IPv4 DNS server - 192.0.2.200
    • An IPv6 DNS server - 2001:db8:1::ffbb
    • A DNS search domain - example.com
    • 802.1X network authentication using the TLS EAP protocol
  2. Apply the settings to the system:

    # nmstatectl apply ~/create-ethernet-profile.yml

Verification

  • Access resources on the network that require network authentication.

18.3. Configuring a static Ethernet connection with 802.1X network authentication by using the network RHEL System Role

You can remotely configure an Ethernet connection with 802.1X network authentication by using the network RHEL System Role.

Perform this procedure on the Ansible control node.

Prerequisites

  • You have prepared the control node and the managed nodes
  • You are logged in to the control node as a user who can run playbooks on the managed nodes.
  • The account you use to connect to the managed nodes has sudo permissions on them.
  • The managed nodes or groups of managed nodes on which you want to run this playbook are listed in the Ansible inventory file
  • The network supports 802.1X network authentication.
  • The managed nodes uses NetworkManager.
  • The following files required for TLS authentication exist on the control node:

    • The client key is stored in the /srv/data/client.key file.
    • The client certificate is stored in the /srv/data/client.crt file.
    • The Certificate Authority (CA) certificate is stored in the /srv/data/ca.crt file.

Procedure

  1. Create a playbook file, for example ~/enable-802.1x.yml, with the following content:

    ---
    - name: Configure an Ethernet connection with 802.1X authentication
      hosts: managed-node-01.example.com
      tasks:
        - name: Copy client key for 802.1X authentication
          copy:
            src: "/srv/data/client.key"
            dest: "/etc/pki/tls/private/client.key"
            mode: 0600
    
        - name: Copy client certificate for 802.1X authentication
          copy:
            src: "/srv/data/client.crt"
            dest: "/etc/pki/tls/certs/client.crt"
    
        - name: Copy CA certificate for 802.1X authentication
          copy:
            src: "/srv/data/ca.crt"
            dest: "/etc/pki/ca-trust/source/anchors/ca.crt"
    
        - include_role:
            name: rhel-system-roles.network
    
          vars:
            network_connections:
              - name: enp1s0
                type: ethernet
                autoconnect: yes
                ip:
                  address:
                    - 192.0.2.1/24
                    - 2001:db8:1::1/64
                  gateway4: 192.0.2.254
                  gateway6: 2001:db8:1::fffe
                  dns:
                    - 192.0.2.200
                    - 2001:db8:1::ffbb
                  dns_search:
                    - example.com
                ieee802_1x:
                  identity: user_name
                  eap: tls
                  private_key: "/etc/pki/tls/private/client.key"
                  private_key_password: "password"
                  client_cert: "/etc/pki/tls/certs/client.crt"
                  ca_cert: "/etc/pki/ca-trust/source/anchors/ca.crt"
                  domain_suffix_match: example.com
                state: up

    These settings define an Ethernet connection profile for the enp1s0 device with the following settings:

    • A static IPv4 address - 192.0.2.1 with a /24 subnet mask
    • A static IPv6 address - 2001:db8:1::1 with a /64 subnet mask
    • An IPv4 default gateway - 192.0.2.254
    • An IPv6 default gateway - 2001:db8:1::fffe
    • An IPv4 DNS server - 192.0.2.200
    • An IPv6 DNS server - 2001:db8:1::ffbb
    • A DNS search domain - example.com
    • 802.1X network authentication using the TLS Extensible Authentication Protocol (EAP)
  2. Validate the playbook syntax:

    # ansible-playbook ~/enable-802.1x.yml --syntax-check

    Note that this command only validates the syntax and does not protect against a wrong but valid configuration.

  3. Run the playbook:

    # ansible-playbook ~/enable-802.1x.yml

Additional resources

  • /usr/share/ansible/roles/rhel-system-roles.network/README.md file

18.4. Configuring a wifi connection with 802.1X network authentication by using the network RHEL System Role

Using RHEL System Roles, you can automate the creation of a wifi connection. For example, you can remotely add a wireless connection profile for the wlp1s0 interface using an Ansible Playbook. The created profile uses the 802.1X standard to authenticate the client to a wifi network. The playbook configures the connection profile to use DHCP. To configure static IP settings, adapt the parameters in the ip dictionary accordingly.

Perform this procedure on the Ansible control node.

Prerequisites

  • You have prepared the control node and the managed nodes
  • You are logged in to the control node as a user who can run playbooks on the managed nodes.
  • The account you use to connect to the managed nodes has sudo permissions on them.
  • The managed nodes or groups of managed nodes on which you want to run this playbook are listed in the Ansible inventory file.
  • The network supports 802.1X network authentication.
  • You installed the wpa_supplicant package on the managed node.
  • DHCP is available in the network of the managed node.
  • The following files required for TLS authentication exist on the control node:

    • The client key is stored in the /srv/data/client.key file.
    • The client certificate is stored in the /srv/data/client.crt file.
    • The CA certificate is stored in the /srv/data/ca.crt file.

Procedure

  1. Create a playbook file, for example ~/enable-802.1x.yml, with the following content:

    ---
    - name: Configure a wifi connection with 802.1X authentication
      hosts: managed-node-01.example.com
      tasks:
        - name: Copy client key for 802.1X authentication
          copy:
            src: "/srv/data/client.key"
            dest: "/etc/pki/tls/private/client.key"
            mode: 0400
    
        - name: Copy client certificate for 802.1X authentication
          copy:
            src: "/srv/data/client.crt"
            dest: "/etc/pki/tls/certs/client.crt"
    
        - name: Copy CA certificate for 802.1X authentication
          copy:
            src: "/srv/data/ca.crt"
            dest: "/etc/pki/ca-trust/source/anchors/ca.crt"
    
        - block:
            - import_role:
                name: linux-system-roles.network
              vars:
                network_connections:
                  - name: Configure the Example-wifi profile
                    interface_name: wlp1s0
                    state: up
                    type: wireless
                    autoconnect: yes
                    ip:
                      dhcp4: true
                      auto6: true
                    wireless:
                      ssid: "Example-wifi"
                      key_mgmt: "wpa-eap"
                    ieee802_1x:
                      identity: "user_name"
                      eap: tls
                      private_key: "/etc/pki/tls/client.key"
                      private_key_password: "password"
                      private_key_password_flags: none
                      client_cert: "/etc/pki/tls/client.pem"
                      ca_cert: "/etc/pki/tls/cacert.pem"
                      domain_suffix_match: "example.com"

    These settings define a wifi connection profile for the wlp1s0 interface. The profile uses 802.1X standard to authenticate the client to the wifi network. The connection retrieves IPv4 addresses, IPv6 addresses, default gateway, routes, DNS servers, and search domains from a DHCP server and IPv6 stateless address autoconfiguration (SLAAC).

  2. Validate the playbook syntax:

    # ansible-playbook ~/enable-802.1x.yml --syntax-check

    Note that this command only validates the syntax and does not protect against a wrong but valid configuration.

  3. Run the playbook:

    # ansible-playbook ~/enable-802.1x.yml

Additional resources

  • /usr/share/ansible/roles/rhel-system-roles.network/README.md file

Chapter 19. Managing the default gateway setting

The default gateway is a router that forwards network packets when no other route matches the destination of a packet. In a local network, the default gateway is typically the host that is one hop closer to the internet.

19.1. Setting the default gateway on an existing connection by using nmcli

In most situations, administrators set the default gateway when they create a connection as explained in, for example, Configuring an Ethernet connection by using nmcli.

In most situations, administrators set the default gateway when they create a connection. However, you can also set or update the default gateway setting on a previously created connection using the nmcli utility.

Prerequisites

  • At least one static IP address must be configured on the connection on which the default gateway will be set.
  • If the user is logged in on a physical console, user permissions are sufficient. Otherwise, user must have root permissions.

Procedure

  1. Set the IP address of the default gateway.

    For example, to set the IPv4 address of the default gateway on the example connection to 192.0.2.1:

    # nmcli connection modify example ipv4.gateway "192.0.2.1"

    For example, to set the IPv6 address of the default gateway on the example connection to 2001:db8:1::1:

    # nmcli connection modify example ipv6.gateway "2001:db8:1::1"
  2. Restart the network connection for changes to take effect. For example, to restart the example connection using the command line:

    # nmcli connection up example
    Warning

    All connections currently using this network connection are temporarily interrupted during the restart.

  3. Optionally, verify that the route is active.

    To display the IPv4 default gateway:

    # ip -4 route
    default via 192.0.2.1 dev example proto static metric 100

    To display the IPv6 default gateway:

    # ip -6 route
    default via 2001:db8:1::1 dev example proto static metric 100 pref medium

19.2. Setting the default gateway on an existing connection by using the nmcli interactive mode

In most situations, administrators set the default gateway when they create a connection as explained in, for example, * Configuring an Ethernet connection by using the nmcli interactive editor

In most situations, administrators set the default gateway when they create a connection. However, you can also set or update the default gateway setting on a previously created connection using the interactive mode of the nmcli utility.

Prerequisites

  • At least one static IP address must be configured on the connection on which the default gateway will be set.
  • If the user is logged in on a physical console, user permissions are sufficient. Otherwise, the user must have root permissions.

Procedure

  1. Open the nmcli interactive mode for the required connection. For example, to open the nmcli interactive mode for the example connection:

    # nmcli connection edit example
  2. Set the default gateway.

    For example, to set the IPv4 address of the default gateway on the example connection to 192.0.2.1:

    nmcli> set ipv4.gateway 192.0.2.1

    For example, to set the IPv6 address of the default gateway on the example connection to 2001:db8:1::1:

    nmcli> set ipv6.gateway 2001:db8:1::1
  3. Optionally, verify that the default gateway was set correctly:

    nmcli> print
    ...
    ipv4.gateway:                           192.0.2.1
    ...
    ipv6.gateway:                           2001:db8:1::1
    ...
  4. Save the configuration:

    nmcli> save persistent
  5. Restart the network connection for changes to take effect:

    nmcli> activate example
    Warning

    All connections currently using this network connection are temporarily interrupted during the restart.

  6. Leave the nmcli interactive mode:

    nmcli> quit
  7. Optionally, verify that the route is active.

    To display the IPv4 default gateway:

    # ip -4 route
    default via 192.0.2.1 dev example proto static metric 100

    To display the IPv6 default gateway:

    # ip -6 route
    default via 2001:db8:1::1 dev example proto static metric 100 pref medium

19.3. Setting the default gateway on an existing connection by using nm-connection-editor

In most situations, administrators set the default gateway when they create a connection. However, you can also set or update the default gateway setting on a previously created connection using the nm-connection-editor application.

Prerequisites

  • At least one static IP address must be configured on the connection on which the default gateway will be set.

Procedure

  1. Open a terminal, and enter nm-connection-editor:

    # nm-connection-editor
  2. Select the connection to modify, and click the gear wheel icon to edit the existing connection.
  3. Set the IPv4 default gateway. For example, to set the IPv4 address of the default gateway on the connection to 192.0.2.1:

    1. Open the IPv4 Settings tab.
    2. Enter the address in the gateway field next to the IP range the gateway’s address is within:

      set default gw in nm connection editor ipv4

  4. Set the IPv6 default gateway. For example, to set the IPv6 address of the default gateway on the connection to 2001:db8:1::1:

    1. Open the IPv6 tab.
    2. Enter the address in the gateway field next to the IP range the gateway’s address is within:

      set default gw in nm connection editor ipv6

  5. Click OK.
  6. Click Save.
  7. Restart the network connection for changes to take effect. For example, to restart the example connection using the command line:

    # nmcli connection up example
    Warning

    All connections currently using this network connection are temporarily interrupted during the restart.

  8. Optionally, verify that the route is active.

    To display the IPv4 default gateway:

    # ip -4 route
    default via 192.0.2.1 dev example proto static metric 100

    To display the IPv6 default gateway:

    # ip -6 route
    default via 2001:db8:1::1 dev example proto static metric 100 pref medium

19.4. Setting the default gateway on an existing connection by using control-center

In most situations, administrators set the default gateway when they create a connection. However, you can also set or update the default gateway setting on a previously created connection using the control-center application.

Prerequisites

  • At least one static IP address must be configured on the connection on which the default gateway will be set.
  • The network configuration of the connection is open in the control-center application.

Procedure

  1. Set the IPv4 default gateway. For example, to set the IPv4 address of the default gateway on the connection to 192.0.2.1:

    1. Open the IPv4 tab.
    2. Enter the address in the gateway field next to the IP range the gateway’s address is within:

      set default gw in control center ipv4

  2. Set the IPv6 default gateway. For example, to set the IPv6 address of the default gateway on the connection to 2001:db8:1::1:

    1. Open the IPv6 tab.
    2. Enter the address in the gateway field next to the IP range the gateway’s address is within:

      set default gw in control center ipv6

  3. Click Apply.
  4. Back in the Network window, disable and re-enable the connection by switching the button for the connection to Off and back to On for changes to take effect.

    Warning

    All connections currently using this network connection are temporarily interrupted during the restart.

  5. Optionally, verify that the route is active.

    To display the IPv4 default gateway:

    $ ip -4 route
    default via 192.0.2.1 dev example proto static metric 100

    To display the IPv6 default gateway:

    $ ip -6 route
    default via 2001:db8:1::1 dev example proto static metric 100 pref medium

19.5. Setting the default gateway on an existing connection by using nmstatectl

Use the nmstatectl utility to set the default gateway through the Nmstate API. The Nmstate API ensures that, after setting the configuration, the result matches the configuration file. If anything fails, nmstatectl automatically rolls back the changes to avoid leaving the system in an incorrect state.

Prerequisites

  • At least one static IP address must be configured on the connection on which the default gateway will be set.
  • The enp1s0 interface is configured, and the IP address of the default gateway is within the subnet of the IP configuration of this interface.
  • The nmstate package is installed.

Procedure

  1. Create a YAML file, for example ~/set-default-gateway.yml, with the following content:

    ---
    routes:
      config:
      - destination: 0.0.0.0/0
        next-hop-address: 192.0.2.1
        next-hop-interface: enp1s0

    These settings define 192.0.2.1 as the default gateway, and the default gateway is reachable through the enp1s0 interface.

  2. Apply the settings to the system:

    # nmstatectl apply ~/set-default-gateway.yml

Additional resources

  • nmstatectl(8) man page
  • /usr/share/doc/nmstate/examples/ directory

19.6. Setting the default gateway on an existing connection by using the network RHEL System Role

You can use the network RHEL System Role to set the default gateway.

Important

When you run a play that uses the network RHEL System Role and if the setting values do not match the values specified in the play, the role overrides the existing connection profile with the same name. To prevent resetting these values to their defaults, always specify the whole configuration of the network connection profile in the play, even if the configuration, for example the IP configuration, already exists.

Depending on whether it already exists, the procedure creates or updates the enp1s0 connection profile with the following settings:

  • A static IPv4 address - 198.51.100.20 with a /24 subnet mask
  • A static IPv6 address - 2001:db8:1::1 with a /64 subnet mask
  • An IPv4 default gateway - 198.51.100.254
  • An IPv6 default gateway - 2001:db8:1::fffe
  • An IPv4 DNS server - 198.51.100.200
  • An IPv6 DNS server - 2001:db8:1::ffbb
  • A DNS search domain - example.com

Perform this procedure on the Ansible control node.

Prerequisites

  • You have prepared the control node and the managed nodes
  • You are logged in to the control node as a user who can run playbooks on the managed nodes.
  • The account you use to connect to the managed nodes has sudo permissions on them.
  • The managed nodes or groups of managed nodes on which you want to run this playbook are listed in the Ansible inventory file.

Procedure

  1. Create a playbook file, for example ~/ethernet-connection.yml, with the following content:

    ---
    - name: Configure the network
      hosts: managed-node-01.example.com
      tasks:
      - name: Configure an Ethernet connection with static IP and default gateway
        include_role:
          name: rhel-system-roles.network
    
        vars:
          network_connections:
            - name: enp1s0
              type: ethernet
              autoconnect: yes
              ip:
                address:
                  - 198.51.100.20/24
                  - 2001:db8:1::1/64
                gateway4: 198.51.100.254
                gateway6: 2001:db8:1::fffe
                dns:
                  - 198.51.100.200
                  - 2001:db8:1::ffbb
                dns_search:
                  - example.com
              state: up
  2. Validate the playbook syntax:

    # ansible-playbook ~/ethernet-connection.yml --syntax-check

    Note that this command only validates the syntax and does not protect against a wrong but valid configuration.

  3. Run the playbook:

    # ansible-playbook ~/ethernet-connection.yml

Additional resources

  • /usr/share/ansible/roles/rhel-system-roles.network/README.md file

19.7. How NetworkManager manages multiple default gateways

In certain situations, for example for fallback reasons, you set multiple default gateways on a host. However, to avoid asynchronous routing issues, each default gateway of the same protocol requires a separate metric value. Note that RHEL only uses the connection to the default gateway that has the lowest metric set.

You can set the metric for both the IPv4 and IPv6 gateway of a connection using the following command:

# nmcli connection modify connection-name ipv4.route-metric value ipv6.route-metric value
Important

Do not set the same metric value for the same protocol in multiple connection profiles to avoid routing issues.

If you set a default gateway without a metric value, NetworkManager automatically sets the metric value based on the interface type. For that, NetworkManager assigns the default value of this network type to the first connection that is activated, and sets an incremented value to each other connection of the same type in the order they are activated. For example, if two Ethernet connections with a default gateway exist, NetworkManager sets a metric of 100 on the route to the default gateway of the connection that you activate first. For the second connection, NetworkManager sets 101.

The following is an overview of frequently-used network types and their default metrics:

Connection typeDefault metric value

VPN

50

Ethernet

100

MACsec

125

InfiniBand

150

Bond

300

Team

350

VLAN

400

Bridge

425

TUN

450

Wi-Fi

600

IP tunnel

675

19.8. Configuring NetworkManager to avoid using a specific profile to provide a default gateway

You can configure that NetworkManager never uses a specific profile to provide the default gateway. Follow this procedure for connection profiles that are not connected to the default gateway.

Prerequisites

  • The NetworkManager connection profile for the connection that is not connected to the default gateway exists.

Procedure

  1. If the connection uses a dynamic IP configuration, configure that NetworkManager does not use the connection as the default route for IPv4 and IPv6 connections:

    # nmcli connection modify connection_name ipv4.never-default yes ipv6.never-default yes

    Note that setting ipv4.never-default and ipv6.never-default to yes, automatically removes the default gateway’s IP address for the corresponding protocol from the connection profile.

  2. Activate the connection:

    # nmcli connection up connection_name

Verification

  • Use the ip -4 route and ip -6 route commands to verify that RHEL does not use the network interface for the default route for the IPv4 and IPv6 protocol.

19.9. Fixing unexpected routing behavior due to multiple default gateways

There are only a few scenarios, such as when using multipath TCP, in which you require multiple default gateways on a host. In most cases, you configure only a single default gateway to avoid unexpected routing behavior or asynchronous routing issues.

Note

To route traffic to different internet providers, use policy-based routing instead of multiple default gateways.

Prerequisites

  • The host uses NetworkManager to manage network connections, which is the default.
  • The host has multiple network interfaces.
  • The host has multiple default gateways configured.

Procedure

  1. Display the routing table:

    • For IPv4, enter:

      # ip -4 route
      default via 192.0.2.1 dev enp1s0 proto static metric 101
      default via 198.51.100.1 dev enp7s0 proto static metric 102
      ...
    • For IPv6, enter:

      # ip -6 route
      default via 2001:db8:1::1 dev enp1s0 proto static metric 101 pref medium
      default via 2001:db8:2::1 dev enp7s0 proto static metric 102 pref medium
      ...

    Entries starting with default indicate a default route. Note the interface names of these entries displayed next to dev.

  2. Use the following commands to display the NetworkManager connections that use the interfaces you identified in the previous step:

    # nmcli -f GENERAL.CONNECTION,IP4.GATEWAY,IP6.GATEWAY device show enp1s0
    GENERAL.CONNECTION:      Corporate-LAN
    IP4.GATEWAY:             192.0.2.1
    IP6.GATEWAY:             2001:db8:1::1
    
    # nmcli -f GENERAL.CONNECTION,IP4.GATEWAY,IP6.GATEWAY device show enp7s0
    GENERAL.CONNECTION:      Internet-Provider
    IP4.GATEWAY:             198.51.100.1
    IP6.GATEWAY:             2001:db8:2::1

    In these examples, the profiles named Corporate-LAN and Internet-Provider have the default gateways set. Because, in a local network, the default gateway is typically the host that is one hop closer to the internet, the rest of this procedure assumes that the default gateways in the Corporate-LAN are incorrect.

  3. Configure that NetworkManager does not use the Corporate-LAN connection as the default route for IPv4 and IPv6 connections:

    # nmcli connection modify Corporate-LAN ipv4.never-default yes ipv6.never-default yes

    Note that setting ipv4.never-default and ipv6.never-default to yes, automatically removes the default gateway’s IP address for the corresponding protocol from the connection profile.

  4. Activate the Corporate-LAN connection:

    # nmcli connection up Corporate-LAN

Verification

  • Display the IPv4 and IPv6 routing tables and verify that only one default gateway is available for each protocol:

    • For IPv4, enter:

      # ip -4 route
      default via 192.0.2.1 dev enp1s0 proto static metric 101
      ...
    • For IPv6, enter:

      # ip -6 route
      default via 2001:db8:1::1 dev enp1s0 proto static metric 101 pref medium
      ...

Chapter 20. Configuring static routes

Routing ensures that you can send and receive traffic between mutually-connected networks. In larger environments, administrators typically configure services so that routers can dynamically learn about other routers. In smaller environments, administrators often configure static routes to ensure that traffic can reach from one network to the next.

You need static routes to achieve a functioning communication among multiple networks if all of these conditions apply:

  • The traffic has to pass multiple networks.
  • The exclusive traffic flow through the default gateways is not sufficient.

Section 20.1, “Example of a network that requires static routes” describes scenarios and how the traffic flows between different networks when you do not configure static routes.

20.1. Example of a network that requires static routes

You require static routes in this example because not all IP networks are directly connected through one router. Without the static routes, some networks cannot communicate with each other. Additionally, traffic from some networks flows only in one direction.

Note

The network topology in this example is artificial and only used to explain the concept of static routing. It is not a recommended topology in production environments.

For a functioning communication among all networks in this example, configure a static route to Raleigh (198.51.100.0/24) with next the hop Router 2 (203.0.113.10). The IP address of the next hop is the one of Router 2 in the data center network (203.0.113.0/24).

You can configure the static route as follows:

  • For a simplified configuration, set this static route only on Router 1. However, this increases the traffic on Router 1 because hosts from the data center (203.0.113.0/24) send traffic to Raleigh (198.51.100.0/24) always through Router 1 to Router 2.
  • For a more complex configuration, configure this static route on all hosts in the data center (203.0.113.0/24). All hosts in this subnet then send traffic directly to Router 2 (203.0.113.10) that is closer to Raleigh (198.51.100.0/24).

For more details between which networks traffic flows or not, see the explanations below the diagram.

routing example

In case that the required static routes are not configured, the following are the situations in which the communication works and when it does not:

  • Hosts in the Berlin network (192.0.2.0/24):

    • Can communicate with other hosts in the same subnet because they are directly connected.
    • Can communicate with the internet because Router 1 is in the Berlin network (192.0.2.0/24) and has a default gateway, which leads to the internet.
    • Can communicate with the data center network (203.0.113.0/24) because Router 1 has interfaces in both the Berlin (192.0.2.0/24) and the data center (203.0.113.0/24) networks.
    • Cannot communicate with the Raleigh network (198.51.100.0/24) because Router 1 has no interface in this network. Therefore, Router 1 sends the traffic to its own default gateway (internet).
  • Hosts in the data center network (203.0.113.0/24):

    • Can communicate with other hosts in the same subnet because they are directly connected.
    • Can communicate with the internet because they have their default gateway set to Router 1, and Router 1 has interfaces in both networks, the data center (203.0.113.0/24) and to the internet.
    • Can communicate with the Berlin network (192.0.2.0/24) because they have their default gateway set to Router 1, and Router 1 has interfaces in both the data center (203.0.113.0/24) and the Berlin (192.0.2.0/24) networks.
    • Cannot communicate with the Raleigh network (198.51.100.0/24) because the data center network has no interface in this network. Therefore, hosts in the data center (203.0.113.0/24) send traffic to their default gateway (Router 1). Router 1 also has no interface in the Raleigh network (198.51.100.0/24) and, as a result, Router 1 sends this traffic to its own default gateway (internet).
  • Hosts in the Raleigh network (198.51.100.0/24):

    • Can communicate with other hosts in the same subnet because they are directly connected.
    • Cannot communicate with hosts on the internet. Router 2 sends the traffic to Router 1 because of the default gateway settings. The actual behavior of Router 1 depends on the reverse path filter (rp_filter) system control (sysctl) setting. By default on RHEL, Router 1 drops the outgoing traffic instead of routing it to the internet. However, regardless of the configured behavior, communication is not possible without the static route.
    • Cannot communicate with the data center network (203.0.113.0/24). The outgoing traffic reaches the destination through Router 2 because of the default gateway setting. However, replies to packets do not reach the sender because hosts in the data center network (203.0.113.0/24) send replies to their default gateway (Router 1). Router 1 then sends the traffic to the internet.
    • Cannot communicate with the Berlin network (192.0.2.0/24). Router 2 sends the traffic to Router 1 because of the default gateway settings. The actual behavior of Router 1 depends on the rp_filter sysctl setting. By default on RHEL, Router 1 drops the outgoing traffic instead of sending it to the Berlin network (192.0.2.0/24). However, regardless of the configured behavior, communication is not possible without the static route.
Note

In addition to configuring the static routes, you must enable IP forwarding on both routers.

20.2. How to use the nmcli command to configure a static route

To configure a static route, use the nmcli utility with the following syntax:

$ nmcli connection modify connection_name ipv4.routes "ip[/prefix] [next_hop] [metric] [attribute=value] [attribute=value] ..."

The command supports the following route attributes:

  • cwnd=n: Sets the congestion window (CWND) size, defined in number of packets.
  • lock-cwnd=true|false: Defines whether or not the kernel can update the CWND value.
  • lock-mtu=true|false: Defines whether or not the kernel can update the MTU to path MTU discovery.
  • lock-window=true|false: Defines whether or not the kernel can update the maximum window size for TCP packets.
  • mtu=n: Sets the maximum transfer unit (MTU) to use along the path to the destination.
  • onlink=true|false: Defines whether the next hop is directly attached to this link even if it does not match any interface prefix.
  • scope=n: For an IPv4 route, this attribute sets the scope of the destinations covered by the route prefix. Set the value as an integer (0-255).
  • src=address: Sets the source address to prefer when sending traffic to the destinations covered by the route prefix.
  • table=table_id: Sets the ID of the table the route should be added to. If you omit this parameter, NetworkManager uses the main table.
  • tos=n: Sets the type of service (TOS) key. Set the value as an integer (0-255).
  • type=value: Sets the route type. NetworkManager supports the unicast, local, blackhole, unreachable, prohibit, and throw route types. The default is unicast.
  • window=n: Sets the maximal window size for TCP to advertise to these destinations, measured in bytes.

If you use the ipv4.routes sub-command, nmcli overrides all current settings of this parameter.

To add a route:

$ nmcli connection modify connection_name +ipv4.routes "<route>"

Similarly, to remove a specific route:

$ nmcli connection modify connection_name -ipv4.routes "<route>"

20.3. Configuring a static route by using nmcli

You can add a static route to an existing NetworkManager connection profile using the nmcli connection modify command.

The procedure below configures the following routes:

  • An IPv4 route to the remote 198.51.100.0/24 network. The corresponding gateway with the IP address 192.0.2.10 is reachable through the example connection.
  • An IPv6 route to the remote 2001:db8:2::/64 network. The corresponding gateway with the IP address 2001:db8:1::10 is reachable through the example connection.

Prerequisites

  • The example connection profile exists and it configures this host to be in the same IP subnet as the gateways.

Procedure

  1. Add the static IPv4 route to the example connection profile:

    # nmcli connection modify example +ipv4.routes "198.51.100.0/24 192.0.2.10"

    To set multiple routes in one step, pass the individual routes comma-separated to the command. For example, to add a route to the 198.51.100.0/24 and 203.0.113.0/24 networks, both routed through the 192.0.2.10 gateway, enter:

    # nmcli connection modify example +ipv4.routes "198.51.100.0/24 192.0.2.10, 203.0.113.0/24 192.0.2.10"
  2. Add the static IPv6 route to the example connection profile:

    # nmcli connection modify example +ipv6.routes "2001:db8:2::/64 2001:db8:1::10"
  3. Re-activate the connection:

    # nmcli connection up example

Verification

  1. Display the IPv4 routes:

    # ip -4 route
    ...
    198.51.100.0/24 via 192.0.2.10 dev enp1s0
  2. Display the IPv6 routes:

    # ip -6 route
    ...
    2001:db8:2::/64 via 2001:db8:1::10 dev enp1s0 metric 1024 pref medium

Additional resources

  • nmcli(1) man page
  • nm-settings-nmcli(5) man page

20.4. Configuring a static route by using nmtui

The nmtui application provides a text-based user interface for NetworkManager. You can use nmtui to configure static routes on a host without a graphical interface.

For example, the procedure below adds a route to the 192.0.2.0/24 network that uses the gateway running on 198.51.100.1, which is reachable through an existing connection profile.

Note

In nmtui:

  • Navigate by using the cursor keys.
  • Press a button by selecting it and hitting Enter.
  • Select and deselect checkboxes by using Space.

Prerequisites

  • The network is configured.
  • The gateway for the static route must be directly reachable on the interface.
  • If the user is logged in on a physical console, user permissions are sufficient. Otherwise, the command requires root permissions.

Procedure

  1. Start nmtui:

    # nmtui
  2. Select Edit a connection, and press Enter.
  3. Select the connection profile through which you can reach the next hop to the destination network, and press Enter.
  4. Depending on whether it is an IPv4 or IPv6 route, press the Show button next to the protocol’s configuration area.
  5. Press the Edit button next to Routing. This opens a new window where you configure static routes:

    1. Press the Add button and fill in:

      • The destination network, including the prefix in Classless Inter-Domain Routing (CIDR) format
      • The IP address of the next hop
      • A metric value, if you add multiple routes to the same network and want to prioritize the routes by efficiency
    2. Repeat the previous step for every route you want to add and that is reachable through this connection profile.
    3. Press the OK button to return to the window with the connection settings.

      Figure 20.1. Example of a static route without metric

      nmtui add static route
  6. Press the OK button to return to the nmtui main menu.
  7. Select Activate a connection and press Enter.
  8. Select the connection profile that you edited, and press Enter twice to deactivate and activate it again.

    Important

    Skip this step if you run nmtui over a remote connection, such as SSH, that uses the connection profile you want to reactivate. In this case, if you would deactivate it in nmtui, the connection is terminated and, consequently, you cannot activate it again. To avoid this problem, use the nmcli connection connection_profile_name up command to reactivate the connection in the mentioned scenario.

  9. Press the Back button to return to the main menu.
  10. Select Quit, and press Enter to close the nmtui application.

Verification

  • Verify that the route is active:

    $ ip route
    ...
    192.0.2.0/24 via 198.51.100.1 dev example proto static metric 100

20.5. Configuring a static route by using control-center

You can use control-center in GNOME to add a static route to the configuration of a network connection.

The procedure below configures the following routes:

  • An IPv4 route to the remote 198.51.100.0/24 network. The corresponding gateway has the IP address 192.0.2.10.
  • An IPv6 route to the remote 2001:db8:2::/64 network. The corresponding gateway has the IP address 2001:db8:1::10.

Prerequisites

Procedure

  1. On the IPv4 tab:

    1. Optional: Disable automatic routes by clicking the On button in the Routes section of the IPv4 tab to use only static routes. If automatic routes are enabled, Red Hat Enterprise Linux uses static routes and routes received from a DHCP server.
    2. Enter the address, netmask, gateway, and optionally a metric value of the IPv4 route:

      IPv4 static route in control center

  2. On the IPv6 tab:

    1. Optional: Disable automatic routes by clicking the On button i the Routes section of the IPv4 tab to use only static routes.
    2. Enter the address, netmask, gateway, and optionally a metric value of the IPv6 route:

      IPv6 static route in control center

  3. Click Apply.
  4. Back in the Network window, disable and re-enable the connection by switching the button for the connection to Off and back to On for changes to take effect.

    Warning

    Restarting the connection briefly disrupts connectivity on that interface.

Verification

  1. Display the IPv4 routes:

    # ip -4 route
    ...
    198.51.100.0/24 via 192.0.2.10 dev enp1s0
  2. Display the IPv6 routes:

    # ip -6 route
    ...
    2001:db8:2::/64 via 2001:db8:1::10 dev enp1s0 metric 1024 pref medium

20.6. Configuring a static route by using nm-connection-editor

You can use the nm-connection-editor application to add a static route to the configuration of a network connection.

The procedure below configures the following routes:

  • An IPv4 route to the remote 198.51.100.0/24 network. The corresponding gateway with the IP address 192.0.2.10 is reachable through the example connection.
  • An IPv6 route to the remote 2001:db8:2::/64 network. The corresponding gateway with the IP address 2001:db8:1::10 is reachable through the example connection.

Prerequisites

  • The network is configured.
  • This host is in the same IP subnet as the gateways.

Procedure

  1. Open a terminal, and enter nm-connection-editor:

    $ nm-connection-editor
  2. Select the example connection profile, and click the gear wheel icon to edit the existing connection.
  3. On the IPv4 Settings tab:

    1. Click the Routes button.
    2. Click the Add button and enter the address, netmask, gateway, and optionally a metric value.

      IPv4 static route in nm connection editor

    3. Click OK.
  4. On the IPv6 Settings tab:

    1. Click the Routes button.
    2. Click the Add button and enter the address, netmask, gateway, and optionally a metric value.

      IPv6 static route in nm connection editor

    3. Click OK.
  5. Click Save.
  6. Restart the network connection for changes to take effect. For example, to restart the example connection using the command line:

    # nmcli connection up example

Verification

  1. Display the IPv4 routes:

    # ip -4 route
    ...
    198.51.100.0/24 via 192.0.2.10 dev enp1s0
  2. Display the IPv6 routes:

    # ip -6 route
    ...
    2001:db8:2::/64 via 2001:db8:1::10 dev enp1s0 metric 1024 pref medium

20.7. Configuring a static route by using the nmcli interactive mode

You can use the interactive mode of the nmcli utility to add a static route to the configuration of a network connection.

The procedure below configures the following routes:

  • An IPv4 route to the remote 198.51.100.0/24 network. The corresponding gateway with the IP address 192.0.2.10 is reachable through the example connection.
  • An IPv6 route to the remote 2001:db8:2::/64 network. The corresponding gateway with the IP address 2001:db8:1::10 is reachable through the example connection.

Prerequisites

  • The example connection profile exists and it configures this host to be in the same IP subnet as the gateways.

Procedure

  1. Open the nmcli interactive mode for the example connection:

    # nmcli connection edit example
  2. Add the static IPv4 route:

    nmcli> set ipv4.routes 198.51.100.0/24 192.0.2.10
  3. Add the static IPv6 route:

    nmcli> set ipv6.routes 2001:db8:2::/64 2001:db8:1::10
  4. Optionally, verify that the routes were added correctly to the configuration:

    nmcli> print
    ...
    ipv4.routes:    { ip = 198.51.100.0/24, nh = 192.0.2.10 }
    ...
    ipv6.routes:    { ip = 2001:db8:2::/64, nh = 2001:db8:1::10 }
    ...

    The ip attribute displays the network to route and the nh attribute the gateway (next hop).

  5. Save the configuration:

    nmcli> save persistent
  6. Restart the network connection:

    nmcli> activate example
  7. Leave the nmcli interactive mode:

    nmcli> quit

Verification

  1. Display the IPv4 routes:

    # ip -4 route
    ...
    198.51.100.0/24 via 192.0.2.10 dev enp1s0
  2. Display the IPv6 routes:

    # ip -6 route
    ...
    2001:db8:2::/64 via 2001:db8:1::10 dev enp1s0 metric 1024 pref medium

Additional resources

  • nmcli(1) man page
  • nm-settings-nmcli(5) man page

20.8. Configuring a static route by using nmstatectl

Use the nmstatectl utility to configure a static route through the Nmstate API. The Nmstate API ensures that, after setting the configuration, the result matches the configuration file. If anything fails, nmstatectl automatically rolls back the changes to avoid leaving the system in an incorrect state.

Prerequisites

  • The enp1s0 network interface is configured and is in the same IP subnet as the gateways.
  • The nmstate package is installed.

Procedure

  1. Create a YAML file, for example ~/add-static-route-to-enp1s0.yml, with the following content:

    ---
    routes:
      config:
      - destination: 198.51.100.0/24
        next-hop-address: 192.0.2.10
        next-hop-interface: enp1s0
      - destination: 2001:db8:2::/64
        next-hop-address: 2001:db8:1::10
        next-hop-interface: enp1s0

    These settings define the following static routes:

    • An IPv4 route to the remote 198.51.100.0/24 network. The corresponding gateway with the IP address 192.0.2.10 is reachable through the enp1s0 interface.
    • An IPv6 route to the remote 2001:db8:2::/64 network. The corresponding gateway with the IP address 2001:db8:1::10 is reachable through the enp1s0 interface.
  2. Apply the settings to the system:

    # nmstatectl apply ~/add-static-route-to-enp1s0.yml

Verification

  1. Display the IPv4 routes:

    # ip -4 route
    ...
    198.51.100.0/24 via 192.0.2.10 dev enp1s0
  2. Display the IPv6 routes:

    # ip -6 route
    ...
    2001:db8:2::/64 via 2001:db8:1::10 dev enp1s0 metric 1024 pref medium

Additional resources

  • nmstatectl(8) man page
  • /usr/share/doc/nmstate/examples/ directory

20.9. Configuring a static route by using the network RHEL System Role

You can use the network RHEL System Role to configure static routes.

Important

When you run a play that uses the network RHEL System Role and if the setting values do not match the values specified in the play, the role overrides the existing connection profile with the same name. To prevent resetting these values to their defaults, always specify the whole configuration of the network connection profile in the play, even if the configuration, for example the IP configuration, already exists.

Perform this procedure on the Ansible control node.

Prerequisites

  • You have prepared the control node and the managed nodes
  • You are logged in to the control node as a user who can run playbooks on the managed nodes.
  • The account you use to connect to the managed nodes has sudo permissions on them.
  • The managed nodes or groups of managed nodes on which you want to run this playbook are listed in the Ansible inventory file.

Procedure

  1. Create a playbook file, for example ~/add-static-routes.yml, with the following content:

    ---
    - name: Configure the network
      hosts: managed-node-01.example.com
      tasks:
      - name: Configure an Ethernet connection with static IP and additional routes
        include_role:
          name: rhel-system-roles.network
    
        vars:
          network_connections:
            - name: enp7s0
              type: ethernet
              autoconnect: yes
              ip:
                address:
                  - 192.0.2.1/24
                  - 2001:db8:1::1/64
                gateway4: 192.0.2.254
                gateway6: 2001:db8:1::fffe
                dns:
                  - 192.0.2.200
                  - 2001:db8:1::ffbb
                dns_search:
                  - example.com
                route:
                  - network: 198.51.100.0
                    prefix: 24
                    gateway: 192.0.2.10
                  - network: 2001:db8:2::
                    prefix: 64
                    gateway: 2001:db8:1::10
              state: up

    Depending on whether it already exists, the procedure creates or updates the enp7s0 connection profile with the following settings:

    • A static IPv4 address - 192.0.2.1 with a /24 subnet mask
    • A static IPv6 address - 2001:db8:1::1 with a /64 subnet mask
    • An IPv4 default gateway - 192.0.2.254
    • An IPv6 default gateway - 2001:db8:1::fffe
    • An IPv4 DNS server - 192.0.2.200
    • An IPv6 DNS server - 2001:db8:1::ffbb
    • A DNS search domain - example.com
    • Static routes:

      • 198.51.100.0/24 with gateway 192.0.2.10
      • 2001:db8:2::/64 with gateway 2001:db8:1::10
  2. Validate the playbook syntax:

    # ansible-playbook ~/add-static-routes.yml --syntax-check

    Note that this command only validates the syntax and does not protect against a wrong but valid configuration.

  3. Run the playbook:

    # ansible-playbook ~/add-static-routes.yml

Verification

  1. On the managed nodes:

    1. Display the IPv4 routes:

      # ip -4 route
      ...
      198.51.100.0/24 via 192.0.2.10 dev enp7s0
    2. Display the IPv6 routes:

      # ip -6 route
      ...
      2001:db8:2::/64 via 2001:db8:1::10 dev enp7s0 metric 1024 pref medium

Additional resources

  • /usr/share/ansible/roles/rhel-system-roles.network/README.md file

Chapter 21. Configuring policy-based routing to define alternative routes

By default, the kernel in RHEL decides where to forward network packets based on the destination address using a routing table. Policy-based routing enables you to configure complex routing scenarios. For example, you can route packets based on various criteria, such as the source address, packet metadata, or protocol.

Note

On systems that use NetworkManager, only the nmcli utility supports setting routing rules and assigning routes to specific tables.

21.1. Routing traffic from a specific subnet to a different default gateway by using nmcli

You can use policy-based routing to configure a different default gateway for traffic from certain subnets. For example, you can configure RHEL as a router that, by default, routes all traffic to internet provider A using the default route. However, traffic received from the internal workstations subnet is routed to provider B.

The procedure assumes the following network topology:

policy based routing

Prerequisites

  • The system uses NetworkManager to configure the network, which is the default.
  • The RHEL router you want to set up in the procedure has four network interfaces:

    • The enp7s0 interface is connected to the network of provider A. The gateway IP in the provider’s network is 198.51.100.2, and the network uses a /30 network mask.
    • The enp1s0 interface is connected to the network of provider B. The gateway IP in the provider’s network is 192.0.2.2, and the network uses a /30 network mask.
    • The enp8s0 interface is connected to the 10.0.0.0/24 subnet with internal workstations.
    • The enp9s0 interface is connected to the 203.0.113.0/24 subnet with the company’s servers.
  • Hosts in the internal workstations subnet use 10.0.0.1 as the default gateway. In the procedure, you assign this IP address to the enp8s0 network interface of the router.
  • Hosts in the server subnet use 203.0.113.1 as the default gateway. In the procedure, you assign this IP address to the enp9s0 network interface of the router.
  • The firewalld service is enabled and active.

Procedure

  1. Configure the network interface to provider A:

    # nmcli connection add type ethernet con-name Provider-A ifname enp7s0 ipv4.method manual ipv4.addresses 198.51.100.1/30 ipv4.gateway 198.51.100.2 ipv4.dns 198.51.100.200 connection.zone external

    The nmcli connection add command creates a NetworkManager connection profile. The command uses the following options:

    • type ethernet: Defines that the connection type is Ethernet.
    • con-name connection_name: Sets the name of the profile. Use a meaningful name to avoid confusion.
    • ifname network_device: Sets the network interface.
    • ipv4.method manual: Enables to configure a static IP address.
    • ipv4.addresses IP_address/subnet_mask: Sets the IPv4 addresses and subnet mask.
    • ipv4.gateway IP_address: Sets the default gateway address.
    • ipv4.dns IP_of_DNS_server: Sets the IPv4 address of the DNS server.
    • connection.zone firewalld_zone: Assigns the network interface to the defined firewalld zone. Note that firewalld automatically enables masquerading for interfaces assigned to the external zone.
  2. Configure the network interface to provider B:

    # nmcli connection add type ethernet con-name Provider-B ifname enp1s0 ipv4.method manual ipv4.addresses 192.0.2.1/30 ipv4.routes "0.0.0.0/0 192.0.2.2 table=5000" connection.zone external

    This command uses the ipv4.routes parameter instead of ipv4.gateway to set the default gateway. This is required to assign the default gateway for this connection to a different routing table (5000) than the default. NetworkManager automatically creates this new routing table when the connection is activated.

  3. Configure the network interface to the internal workstations subnet:

    # nmcli connection add type ethernet con-name Internal-Workstations ifname enp8s0 ipv4.method manual ipv4.addresses 10.0.0.1/24 ipv4.routes "10.0.0.0/24 table=5000" ipv4.routing-rules "priority 5 from 10.0.0.0/24 table 5000" connection.zone trusted

    This command uses the ipv4.routes parameter to add a static route to the routing table with ID 5000. This static route for the 10.0.0.0/24 subnet uses the IP of the local network interface to provider B (192.0.2.1) as next hop.

    Additionally, the command uses the ipv4.routing-rules parameter to add a routing rule with priority 5 that routes traffic from the 10.0.0.0/24 subnet to table 5000. Low values have a high priority.

    Note that the syntax in the ipv4.routing-rules parameter is the same as in an ip rule add command, except that ipv4.routing-rules always requires specifying a priority.

  4. Configure the network interface to the server subnet:

    # nmcli connection add type ethernet con-name Servers ifname enp9s0 ipv4.method manual ipv4.addresses 203.0.113.1/24 connection.zone trusted

Verification

  1. On a RHEL host in the internal workstation subnet:

    1. Install the traceroute package:

      # dnf install traceroute
    2. Use the traceroute utility to display the route to a host on the internet:

      # traceroute redhat.com
      traceroute to redhat.com (209.132.183.105), 30 hops max, 60 byte packets
       1  10.0.0.1 (10.0.0.1)     0.337 ms  0.260 ms  0.223 ms
       2  192.0.2.1 (192.0.2.1)   0.884 ms  1.066 ms  1.248 ms
       ...

      The output of the command displays that the router sends packets over 192.0.2.1, which is the network of provider B.

  2. On a RHEL host in the server subnet:

    1. Install the traceroute package:

      # dnf install traceroute
    2. Use the traceroute utility to display the route to a host on the internet:

      # traceroute redhat.com
      traceroute to redhat.com (209.132.183.105), 30 hops max, 60 byte packets
       1  203.0.113.1 (203.0.113.1)    2.179 ms  2.073 ms  1.944 ms
       2  198.51.100.2 (198.51.100.2)  1.868 ms  1.798 ms  1.549 ms
       ...

      The output of the command displays that the router sends packets over 198.51.100.2, which is the network of provider A.

Troubleshooting steps

On the RHEL router:

  1. Display the rule list:

    # ip rule list
    0:	from all lookup local
    5:	from 10.0.0.0/24 lookup 5000
    32766:	from all lookup main
    32767:	from all lookup default

    By default, RHEL contains rules for the tables local, main, and default.

  2. Display the routes in table 5000:

    # ip route list table 5000
    0.0.0.0/0 via 192.0.2.2 dev enp1s0 proto static metric 100
    10.0.0.0/24 dev enp8s0 proto static scope link src 192.0.2.1 metric 102
  3. Display the interfaces and firewall zones:

    # firewall-cmd --get-active-zones
    external
      interfaces: enp1s0 enp7s0
    trusted
      interfaces: enp8s0 enp9s0
  4. Verify that the external zone has masquerading enabled:

    # firewall-cmd --info-zone=external
    external (active)
      target: default
      icmp-block-inversion: no
      interfaces: enp1s0 enp7s0
      sources:
      services: ssh
      ports:
      protocols:
      masquerade: yes
      ...

Additional resources

21.2. Routing traffic from a specific subnet to a different default gateway by using the network RHEL System Role

You can use policy-based routing to configure a different default gateway for traffic from certain subnets. For example, you can configure RHEL as a router that, by default, routes all traffic to internet provider A using the default route. However, traffic received from the internal workstations subnet is routed to provider B.

To configure policy-based routing remotely and on multiple nodes, you can use the RHEL network System Role. Perform this procedure on the Ansible control node.

This procedure assumes the following network topology:

policy based routing

Prerequisites

  • You have prepared the control node and the managed nodes
  • You are logged in to the control node as a user who can run playbooks on the managed nodes.
  • The account you use to connect to the managed nodes has sudo permissions on the them.
  • The managed nodes or groups of managed nodes on which you want to run this playbook are listed in the Ansible inventory file.
  • The managed nodes uses the NetworkManager and firewalld services.
  • The managed nodes you want to configure has four network interfaces:

    • The enp7s0 interface is connected to the network of provider A. The gateway IP in the provider’s network is 198.51.100.2, and the network uses a /30 network mask.
    • The enp1s0 interface is connected to the network of provider B. The gateway IP in the provider’s network is 192.0.2.2, and the network uses a /30 network mask.
    • The enp8s0 interface is connected to the 10.0.0.0/24 subnet with internal workstations.
    • The enp9s0 interface is connected to the 203.0.113.0/24 subnet with the company’s servers.
  • Hosts in the internal workstations subnet use 10.0.0.1 as the default gateway. In the procedure, you assign this IP address to the enp8s0 network interface of the router.
  • Hosts in the server subnet use 203.0.113.1 as the default gateway. In the procedure, you assign this IP address to the enp9s0 network interface of the router.

Procedure

  1. Create a playbook file, for example ~/pbr.yml, with the following content:

    ---
    - name: Configuring policy-based routing
      hosts: managed-node-01.example.com
      tasks:
      - name: Routing traffic from a specific subnet to a different default gateway
        include_role:
          name: rhel-system-roles.network
    
        vars:
          network_connections:
            - name: Provider-A
              interface_name: enp7s0
              type: ethernet
              autoconnect: True
              ip:
                address:
                  - 198.51.100.1/30
                gateway4: 198.51.100.2
                dns:
                  - 198.51.100.200
              state: up
              zone: external
    
            - name: Provider-B
              interface_name: enp1s0
              type: ethernet
              autoconnect: True
              ip:
                address:
                  - 192.0.2.1/30
                route:
                  - network: 0.0.0.0
                    prefix: 0
                    gateway: 192.0.2.2
                    table: 5000
              state: up
              zone: external
    
            - name: Internal-Workstations
              interface_name: enp8s0
              type: ethernet
              autoconnect: True
              ip:
                address:
                  - 10.0.0.1/24
                route:
                  - network: 10.0.0.0
                    prefix: 24
                    table: 5000
                routing_rule:
                  - priority: 5
                    from: 10.0.0.0/24
                    table: 5000
              state: up
              zone: trusted
    
            - name: Servers
              interface_name: enp9s0
              type: ethernet
              autoconnect: True
              ip:
                address:
                  - 203.0.113.1/24
              state: up
              zone: trusted
  2. Validate the playbook syntax:

    # ansible-playbook ~/pbr.yml --syntax-check

    Note that this command only validates the syntax and does not protect against a wrong but valid configuration.

  3. Run the playbook:

    # ansible-playbook ~/pbr.yml

Verification

  1. On a RHEL host in the internal workstation subnet:

    1. Install the traceroute package:

      # dnf install traceroute
    2. Use the traceroute utility to display the route to a host on the internet:

      # traceroute redhat.com
      traceroute to redhat.com (209.132.183.105), 30 hops max, 60 byte packets
       1  10.0.0.1 (10.0.0.1)     0.337 ms  0.260 ms  0.223 ms
       2  192.0.2.1 (192.0.2.1)   0.884 ms  1.066 ms  1.248 ms
       ...

      The output of the command displays that the router sends packets over 192.0.2.1, which is the network of provider B.

  2. On a RHEL host in the server subnet:

    1. Install the traceroute package:

      # dnf install traceroute
    2. Use the traceroute utility to display the route to a host on the internet:

      # traceroute redhat.com
      traceroute to redhat.com (209.132.183.105), 30 hops max, 60 byte packets
       1  203.0.113.1 (203.0.113.1)    2.179 ms  2.073 ms  1.944 ms
       2  198.51.100.2 (198.51.100.2)  1.868 ms  1.798 ms  1.549 ms
       ...

      The output of the command displays that the router sends packets over 198.51.100.2, which is the network of provider A.

  3. On the RHEL router that you configured using the RHEL System Role:

    1. Display the rule list:

      # ip rule list
      0:      from all lookup local
      5:    from 10.0.0.0/24 lookup 5000
      32766:  from all lookup main
      32767:  from all lookup default

      By default, RHEL contains rules for the tables local, main, and default.

    2. Display the routes in table 5000:

      # ip route list table 5000
      0.0.0.0/0 via 192.0.2.2 dev enp1s0 proto static metric 100
      10.0.0.0/24 dev enp8s0 proto static scope link src 192.0.2.1 metric 102
    3. Display the interfaces and firewall zones:

      # firewall-cmd --get-active-zones
      external
        interfaces: enp1s0 enp7s0
      trusted
        interfaces: enp8s0 enp9s0
    4. Verify that the external zone has masquerading enabled:

      # firewall-cmd --info-zone=external
      external (active)
        target: default
        icmp-block-inversion: no
        interfaces: enp1s0 enp7s0
        sources:
        services: ssh
        ports:
        protocols:
        masquerade: yes
        ...

Additional resources

  • /usr/share/ansible/roles/rhel-system-roles.network/README.md file

Chapter 22. Configuring NetworkManager DHCP settings

NetworkManager provides different configuration options related to DHCP. For example, you can configure NetworkManager to use the build-in DHCP client (default) or an external client, and you can influence DHCP settings of individual profiles.

22.1. Changing the DHCP client of NetworkManager

By default, NetworkManager uses its internal DHCP client. However, if you require a DHCP client with features that the built-in client does not provide, you can alternatively configure NetworkManager to use dhclient.

Note that RHEL does not provide dhcpcd and, therefore, NetworkManager can not use this client.

Procedure

  1. Create the /etc/NetworkManager/conf.d/dhcp-client.conf file with the following content:

    [main]
    dhcp=dhclient

    You can set the dhcp parameter to internal (default) or dhclient.

  2. If you set the dhcp parameter to dhclient, install the dhcp-client package:

    # dnf install dhcp-client
  3. Restart NetworkManager:

    # systemctl restart NetworkManager

    Note that the restart temporarily interrupts all network connections.

Verification

  • Search in the /var/log/messages log file for an entry similar to the following:

    Apr 26 09:54:19 server NetworkManager[27748]: <info>  [1650959659.8483] dhcp-init: Using DHCP client 'dhclient'

    This log entry confirms that NetworkManager uses dhclient as DHCP client.

Additional resources

  • NetworkManager.conf(5) man page

22.2. Configuring the DHCP behavior of a NetworkManager connection

A Dynamic Host Configuration Protocol (DHCP) client requests the dynamic IP address and corresponding configuration information from a DHCP server each time a client connects to the network.

When you configured a connection to retrieve an IP address from a DHCP server, the NetworkManager requests an IP address from a DHCP server. By default, the client waits 45 seconds for this request to be completed. When a DHCP connection is started, a dhcp client requests an IP address from a DHCP server.

Prerequisites

  • A connection that uses DHCP is configured on the host.

Procedure

  1. Set the ipv4.dhcp-timeout and ipv6.dhcp-timeout properties. For example, to set both options to 30 seconds, enter:

    # nmcli connection modify connection_name ipv4.dhcp-timeout 30 ipv6.dhcp-timeout 30

    Alternatively, set the parameters to infinity to configure that NetworkManager does not stop trying to request and renew an IP address until it is successful.

  2. Optional: Configure the behavior if NetworkManager does not receive an IPv4 address before the timeout:

    # nmcli connection modify connection_name ipv4.may-fail value

    If you set the ipv4.may-fail option to:

    • yes, the status of the connection depends on the IPv6 configuration:

      • If the IPv6 configuration is enabled and successful, NetworkManager activates the IPv6 connection and no longer tries to activate the IPv4 connection.
      • If the IPv6 configuration is disabled or not configured, the connection fails.
    • no, the connection is deactivated. In this case:

      • If the autoconnect property of the connection is enabled, NetworkManager retries to activate the connection as many times as set in the autoconnect-retries property. The default is 4.
      • If the connection still cannot acquire a DHCP address, auto-activation fails. Note that after 5 minutes, the auto-connection process starts again to acquire an IP address from the DHCP server.
  3. Optional: Configure the behavior if NetworkManager does not receive an IPv6 address before the timeout:

    # nmcli connection modify connection_name ipv6.may-fail value

Additional resources

  • nm-settings(5) man page

Chapter 23. Creating a dummy interface

As a Red Hat Enterprise Linux user, you can create and use dummy network interfaces for debugging and testing purposes. A dummy interface provides a device to route packets without actually transmitting them. It enables you to create additional loopback-like devices managed by NetworkManager and makes an inactive SLIP (Serial Line Internet Protocol) address look like a real address for local programs.

23.1. Creating a dummy interface with both an IPv4 and IPv6 address using nmcli

You can create a dummy interface with various settings, such as IPv4 and IPv6 addresses. After creating the interface, NetworkManager automatically assigns it to the default public firewalld zone.

Procedure

  • Create a dummy interface named dummy0 with static IPv4 and IPv6 addresses:

    # nmcli connection add type dummy ifname dummy0 ipv4.method manual ipv4.addresses 192.0.2.1/24 ipv6.method manual ipv6.addresses 2001:db8:2::1/64
    Note

    To configure a dummy interface without IPv4 and IPv6 addresses, set both the ipv4.method and ipv6.method parameters to disabled. Otherwise, IP auto-configuration fails, and NetworkManager deactivates the connection and removes the device.

Verification

  • List the connection profiles:

    # nmcli connection show
    NAME            UUID                                  TYPE     DEVICE
    dummy-dummy0    aaf6eb56-73e5-4746-9037-eed42caa8a65  dummy    dummy0

Additional resources

  • nm-settings(5) man page

Chapter 24. Using nmstate-autoconf to automatically configure the network state using LLDP

Network devices can use the Link Layer Discovery Protocol (LLDP) to advertise their identity, capabilities, and neighbors in a LAN. The nmstate-autoconf utility can use this information to automatically configure local network interfaces.

Important

The nmstate-autoconf utility is provided as a Technology Preview only. Technology Preview features are not supported with Red Hat production Service Level Agreements (SLAs), might not be functionally complete, and Red Hat does not recommend using them for production. These previews provide early access to upcoming product features, enabling customers to test functionality and provide feedback during the development process.

See Technology Preview Features Support Scope on the Red Hat Customer Portal for information about the support scope for Technology Preview features.

24.1. Using nmstate-autoconf to automatically configure network interfaces

The nmstate-autoconf utility uses LLDP to identify the VLAN settings of interfaces connected to a switch to configure local devices.

This procedure assumes the following scenario and that the switch broadcasts the VLAN settings using LLDP:

  • The enp1s0 and enp2s0 interfaces of the RHEL server are connected to switch ports that are configured with VLAN ID 100 and VLAN name prod-net.
  • The enp3s0 interface of the RHEL server is connected to a switch port that is configured with VLAN ID 200 and VLAN name mgmt-net.

The nmstate-autoconf utility then uses this information to create the following interfaces on the server:

  • bond100 - A bond interface with enp1s0 and enp2s0 as ports.
  • prod-net - A VLAN interface on top of bond100 with VLAN ID 100.
  • mgmt-net - A VLAN interface on top of enp3s0 with VLAN ID 200

If you connect multiple network interfaces to different switch ports for which LLDP broadcasts the same VLAN ID, nmstate-autoconf creates a bond with these interfaces and, additionally, configures the common VLAN ID on top of it.

Prerequisites

  • The nmstate package is installed.
  • LLDP is enabled on the network switch.
  • The Ethernet interfaces are up.

Procedure

  1. Enable LLDP on the Ethernet interfaces:

    1. Create a YAML file, for example ~/enable-lldp.yml, with the following content:

      interfaces:
        - name: enp1s0
          type: ethernet
          lldp:
            enabled: true
        - name: enp2s0
          type: ethernet
          lldp:
            enabled: true
        - name: enp3s0
          type: ethernet
          lldp:
            enabled: true
    2. Apply the settings to the system:

      # nmstatectl apply ~/enable-lldp.yml
  2. Configure the network interfaces using LLDP:

    1. Optional, start a dry-run to display and verify the YAML configuration that nmstate-autoconf generates:

      # nmstate-autoconf -d enp1s0,enp2s0,enp3s0
      ---
      interfaces:
      - name: prod-net
        type: vlan
        state: up
        vlan:
          base-iface: bond100
          id: 100
      - name: mgmt-net
        type: vlan
        state: up
        vlan:
          base-iface: enp3s0
          id: 200
      - name: bond100
        type: bond
        state: up
        link-aggregation:
          mode: balance-rr
          port:
          - enp1s0
          - enp2s0
    2. Use nmstate-autoconf to generate the configuration based on information received from LLDP, and apply the settings to the system:

      # nmstate-autoconf enp1s0,enp2s0,enp3s0

Next steps

Verification

  1. Display the settings of the individual interfaces:

    # nmstatectl show <interface_name>

Additional resources

  • nmstate-autoconf(8) man page

Chapter 25. Using LLDP to debug network configuration problems

You can use the Link Layer Discovery Protocol (LLDP) to debug network configuration problems in the topology. This means that, LLDP can report configuration inconsistencies with other hosts or routers and switches.

25.1. Debugging an incorrect VLAN configuration using LLDP information

If you configured a switch port to use a certain VLAN and a host does not receive these VLAN packets, you can use the Link Layer Discovery Protocol (LLDP) to debug the problem. Perform this procedure on the host that does not receive the packets.

Prerequisites

  • The nmstate package is installed.
  • The switch supports LLDP.
  • LLDP is enabled on neighbor devices.

Procedure

  1. Create the ~/enable-LLDP-enp1s0.yml file with the following content:

    interfaces:
      - name: enp1s0
        type: ethernet
        lldp:
          enabled: true
  2. Use the ~/enable-LLDP-enp1s0.yml file to enable LLDP on interface enp1s0:

    # nmstatectl apply ~/enable-LLDP-enp1s0.yml
  3. Display the LLDP information:

    # nmstatectl show enp1s0
    - name: enp1s0
      type: ethernet
      state: up
      ipv4:
        enabled: false
        dhcp: false
      ipv6:
        enabled: false
        autoconf: false
        dhcp: false
      lldp:
        enabled: true
        neighbors:
        - - type: 5
            system-name: Summit300-48
          - type: 6
            system-description: Summit300-48 - Version 7.4e.1 (Build 5)
              05/27/05 04:53:11
          - type: 7
            system-capabilities:
            - MAC Bridge component
            - Router
          - type: 1
            _description: MAC address
            chassis-id: 00:01:30:F9:AD:A0
            chassis-id-type: 4
          - type: 2
            _description: Interface name
            port-id: 1/1
            port-id-type: 5
          - type: 127
            ieee-802-1-vlans:
            - name: v2-0488-03-0505
              vid: 488
            oui: 00:80:c2
            subtype: 3
          - type: 127
            ieee-802-3-mac-phy-conf:
              autoneg: true
              operational-mau-type: 16
              pmd-autoneg-cap: 27648
            oui: 00:12:0f
            subtype: 1
          - type: 127
            ieee-802-1-ppvids:
            - 0
            oui: 00:80:c2
            subtype: 2
          - type: 8
            management-addresses:
            - address: 00:01:30:F9:AD:A0
              address-subtype: MAC
              interface-number: 1001
              interface-number-subtype: 2
          - type: 127
            ieee-802-3-max-frame-size: 1522
            oui: 00:12:0f
            subtype: 4
      mac-address: 82:75:BE:6F:8C:7A
      mtu: 1500
  4. Verify the output to ensure that the settings match your expected configuration. For example, the LLDP information of the interface connected to the switch shows that the switch port this host is connected to uses VLAN ID 448:

    - type: 127
            ieee-802-1-vlans:
            - name: v2-0488-03-0505
              vid: 488

    If the network configuration of the enp1s0 interface uses a different VLAN ID, change it accordingly.

Additional resources

Configuring VLAN tagging

Chapter 26. NetworkManager connection profiles in keyfile format

By default, NetworkManager in Red Hat Enterprise Linux 9 and later stores connection profiles in keyfile format. Unlike the deprecated ifcfg format, the keyfile format supports all connection settings that NetworkManager provides.

26.1. The keyfile format of NetworkManager profiles

The keyfile format is similar to the INI format. For example, the following is an Ethernet connection profile in keyfile format:

[connection]
id=example_connection
uuid=82c6272d-1ff7-4d56-9c7c-0eb27c300029
type=ethernet
autoconnect=true

[ipv4]
method=auto

[ipv6]
method=auto

[ethernet]
mac-address=00:53:00:8f:fa:66

Each section corresponds to a NetworkManager setting name as described in the nm-settings(5) and nm-settings-keyfile(5) man pages. Each key-value-pair in a section is one of the properties listed in the settings specification of the man page.

Most variables in NetworkManager keyfiles have a one-to-one mapping. This means that a NetworkManager property is stored in the keyfile as a variable of the same name and in the same format. However, there are exceptions, mainly to make the keyfile syntax easier to read. For a list of these exceptions, see the nm-settings-keyfile(5) man page.

Important

For security reasons, because connection profiles can contain sensitive information, such as private keys and passphrases, NetworkManager uses only configuration files owned by the root user and that are only readable and writable by root.

Depending on the purpose of the connection profile, save it in one of the following directories:

  • /etc/NetworkManager/system-connections/: The location of persistent profiles. If you modify a persistent profile by using the NetworkManager API, NetworkManager writes and overwrites files in this directory.
  • /run/NetworkManager/system-connections/: For temporary profiles that are automatically removed when you reboot the system.
  • /usr/lib/NetworkManager/system-connections/: For pre-deployed immutable profiles. When you edit such a profile using the NetworkManager API, NetworkManager copies this profile to either the persistent or temporary storage.

NetworkManager does not automatically reload profiles from disk. When you create or update a connection profile in keyfile format, use the nmcli connection reload command to inform NetworkManager about the changes.

26.2. Using nmcli to create keyfile connection profiles in offline mode

Red Hat recommends using NetworkManager utilities, such as nmcli, the network RHEL System Role, or the nmstate API to manage NetworkManager connections, to create and update configuration files. However, you can also create various connection profiles in the keyfile format in offline mode using the nmcli --offline connection add command.

The offline mode ensures that nmcli operates without the NetworkManager service to produce keyfile connection profiles through standard output. This feature can be useful if:

  • You want to create your connection profiles that need to be pre-deployed somewhere. For example in a container image, or as an RPM package.
  • You want to create your connection profiles in an environment where the NetworkManager service is not available. For example when you want to use the chroot utility. Alternatively, when you want to create or modify the network configuration of the RHEL system to be installed through the Kickstart %post script.

You can create the following connection profile types: