1. The /usr/lib/udev/rules.d/60-net.rules file defines that the /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 file.
2. The /usr/lib/udev/rules.d/71-biosdevname.rules file defines that the biosdevname utility renames the interface according to its naming policy, provided that it was not renamed in the previous step.
3. The /usr/lib/udev/rules.d/75-net-description.rules file defines that udev examines the network interface device and sets the properties in udev-internal variables, that will be processed in the next step. Note that some of these properties might be undefined.

4. The /usr/lib/udev/rules.d/80-net-setup-link.rules file calls the net_setup_link udev built-in which then applies the policy. The following is the default policy that is stored in the /usr/lib/systemd/network/99-default.link file:

   [Link]
   NamePolicy=kernel database onboard slot path
   MACAddressPolicy=persistent

   With this policy, if the kernel uses a persistent name, udev does not rename the interface. If the kernel does not use a persistent name, udev renames the interface to the name provided by the hardware database of udev. If this database is not available, Red Hat Enterprise Linux falls back to the mechanisms described above.

   Alternatively, set the NamePolicy parameter in this file to mac for media access control (MAC) address-based interface names.

5. The /usr/lib/udev/rules.d/80-net-setup-link.rules file defines that udev renames the interface based on the udev-internal parameters in the following order:

   1. ID_NET_NAME_ONBOARD
   2. ID_NET_NAME_SLOT
   3. ID_NET_NAME_PATH

   If one parameter is not set, udev uses the next one. If none of the parameters are set, the interface is not renamed.

Procedure

1. Boot the Red Hat Enterprise Linux 8 installation media.
2. In the boot manager, select Install Red Hat Enterprise Linux 8, and press the Tab key to edit the entry.

3. Append the net.ifnames=0 parameter to the kernel command line:

   vmlinuz... net.ifnames=0

4. Press Enter to start the installation.

Procedure

1. Edit the /etc/default/grub file and append the net.ifnames=0 parameter to the GRUB_CMDLINE_LINUX variable:

   GRUB_CMDLINE_LINUX="... *net.ifnames=0

2. Rebuild the grub.cfg file:

   • On a system with UEFI boot mode:

     # grub2-mkconfig -o /boot/efi/EFI/redhat/grub.cfg

   • On a system with legacy boot mode:

     # grub2-mkconfig -o /boot/grub2/grub.cfg

3. If you use interface names in configuration files or scripts, you must manually update them.

4. Reboot the host:

   # reboot

Procedure

1. Set the SYSLOGADDR to the IP address of the syslogd server in the /etc/sysconfig/netconsole file to match the IP address of the syslogd server. For example:

   SYSLOGADDR=192.168.0.1

2. Restart the netconsole.service.

    ~]# systemctl restart netconsole.service

3. Enable netconsole.service to run after rebooting the system.

    ~]# systemctl enable netconsole.service

4. View the netconsole messages from the client in the /var/log/messages file (default) or in the file specified in rsyslog.conf.

    ~]# cat /var/log/messages

Procedure

1. Start the nmtui tool:

   ~]$ nmtui

   The text user interface appears.

   Figure 6.1. The NetworkManager text user interface starting menu

   
2. To navigate, use the arrow keys or press Tab to step forwards and press Shift+Tab to step back through the options. Press Enter to select an option. The Space bar toggles the status of a check box.

1. managed - under the NetworkManager control. A managed device may be connected, meaning that it is activated and configured, or disconnected, meaning that it is not configured but ready to be activated again.
2. unmanaged - NetworkManager does not control it.

Procedure

1. To list the currently available network connections:

   ~]$ nmcli con show
   NAME              UUID                                  TYPE            DEVICE
   Auto Ethernet     9b7f2511-5432-40ae-b091-af2457dfd988  802-3-ethernet  --
   ens3              fb157a65-ad32-47ed-858c-102a48e064a2  802-3-ethernet  ens3
   MyWiFi            91451385-4eb8-4080-8b82-720aab8328dd  802-11-wireless wlan0

   Note that the NAME field in the output always denotes the connection ID (name). It is not the interface name even though it might look the same. In the second connection shown above, ens3 in the NAME field is the connection ID given by the user to the profile applied to the interface ens3. In the last connection shown, the user has assigned the connection ID MyWiFi to the interface wlan0.

   Adding an Ethernet connection means creating a configuration profile which is then assigned to a device. Before creating a new profile, review the available devices as follows:

   ~]$ nmcli device status
   DEVICE  TYPE      STATE         CONNECTION
   ens3    ethernet  disconnected  --
   ens9    ethernet  disconnected  --
   lo      loopback  unmanaged     --

2. To set the device unmanaged by the NetworkManager:

   ~]$ nmcli device set ifname managed no

1. where {COMMON_OPTIONS} are the aliases or property names, see Aliases and Property names.

2. where [IP_OPTIONS] are the IP addresses:

   • For IPv4 addresses: ip4
   • For IPv6 addresses: ip6
3. where [NETMASK] is the network mask width. For example, 255.255.255.0 is the network mask for the prefix 198.51.100.0/24.

4. where [GATEWAY] is the gateway information:

   • For IPv4 addresses: gw4
   • For IPv6 addresses: gw6

1. To create a connection profile with an IPv4 address:

   ~]$ nmcli c add type ethernet ifname enp1s0 con-name "My Connection" ip4 192.168.2.100/24 gw4 192.168.2.1
   Connection 'My Connection' (f0c23472-1aec-4e84-8f1b-be8a2ecbeade) successfully added.

2. To activate the created connection:

   ~]$ nmcli c up _"My Connection"

3. To view the created connection:

   ~]$ nmcli c show "My Connection"

Procedure

1. To modify one or more properties of a connection profile, use the following command:

   ~]$ nmcli c modify

   For example, to change the connection.id from "My Connection" to "My favorite connection" and the connection.interface-name to enp7s0:

   ~]$ nmcli c modify "My Connection" connection.id "My favorite connection" connection.interface-name enp7s0

2. To apply changes after a modified connection using nmcli, activate again the connection by entering:

   ~]$ nmcli con up "My favorite connection"
   Connection successfully activated (D-Bus active path: /org/freedesktop/NetworkManager/ActiveConnection/16)

3. To view the modified connection, enter the nmcli con show con-name command.

Procedure

1. Press the Super key to enter the Activities Overview, type Settings, and press Enter. Then, select the Network tab on the left-hand side, and the Network settings tool appears:

   Figure 8.2. Opening the network settings window

   

2. Click the plus button to add a new connection:

   • For Wired connections, click the plus button next to Wired entry and configure the connection.
   • For VPN connections, click the plus button next to VPN entry. If you want to add an IPsec VPN, click on IPsec based VPN and configure the connection.
   • For Wi-Fi connections, click the Wi-Fi entry on the left-hand side in the Settings menu and configure the connection.

Procedure

1. Add a new NetworkManager connection profile for the Ethernet connection:

   # nmcli connection add con-name Example-Connection ifname enp7s0 type ethernet ipv4.addresses 192.0.2.1/24

   The further steps modify the Example-Connection connection profile you created.

2. Set the IPv6 address:

   # nmcli connection modify Example-Connection ipv6.addresses 2001:db8::1/32

3. Set the IPv4 and IPv6 connection method to manual:

   # nmcli connection modify Example-Connection ipv4.method manual
   # nmcli connection modify Example-Connection ipv6.method manual

4. Set the IPv4 and IPv6 default gateways:

   # nmcli connection modify Example-Connection ipv4.gateway 192.0.2.254
   # nmcli connection modify Example-Connection ipv6.gateway 2001:db8::fffe

5. Set the IPv4 and IPv6 DNS server addresses:

   # nmcli connection modify Example-Connection ipv4.dns "192.0.2.200"
   # nmcli connection modify Example-Connection ipv6.dns "2001:db8::ffbb"

   To set multiple DNS servers, specify them space-separated and enclosed in quotes.

6. Set the DNS search domain for the IPv4 and IPv6 connection:

   # nmcli connection modify Example-Connection ipv4.dns-search example.com
   # nmcli connection modify Example-Connection ipv6.dns-search example.com

7. Active the connection profile:

   # nmcli connection up Example-Connection
   Connection successfully activated (D-Bus active path: /org/freedesktop/NetworkManager/ActiveConnection/13)

Verification steps

1. Display the status of the devices and connections:

   # nmcli device status
   DEVICE      TYPE      STATE      CONNECTION
   enp7s0      ethernet  connected  Example-Connection

2. To display all settings of the connection profile:

   # nmcli connection show Example-Connection
   connection.id:              Example-Connection
   connection.uuid:            b6cdfa1c-e4ad-46e5-af8b-a75f06b79f76
   connection.stable-id:       --
   connection.type:            802-3-ethernet
   connection.interface-name:  enp7s0
   ...

Procedure

1. To change the host name sent by a host to a DHCP server, modify the dhcp-hostname property:

   ~]$ nmcli con modify my-office my-office ipv4.dhcp-hostname host-name ipv6.dhcp-hostname host-name

2. To change the IPv4 client ID sent by a host to a DHCP server, modify the dhcp-client-id property:

   ~]$ nmcli con modify my-office my-office ipv4.dhcp-client-id client-ID-string

   There is no dhcp-client-id property for IPv6, dhclient to create an identifier for IPv6. See the dhclient(8) man page for details.

3. To ignore the DNS servers sent to a host by a DHCP server, modify the ignore-auto-dns property:

   ~]$ nmcli con modify my-office my-office ipv4.ignore-auto-dns yes ipv6.ignore-auto-dns yes

Procedure

1. Press the Super key to enter the Activities Overview, type Settings and press Enter. Then, select the Network menu entry on the left-hand side, and the Network settings tool appears, see Opening the Network Settings Window

2. Select the Wired network interface

   The system creates and configures a single wired connection profile called Wired by default. More than one profile can be created for an interface and applied as needed. The default profile cannot be deleted but its settings can be changed.

3. Edit the default Wired profile by clicking the gear wheel icon to edit an existing connection or click the plus button and then set the configuration options for a new connection.

Procedure

1. Open a terminal, and enter:

   $ nm-connection-editor

2. Click the + button to add a new connection.
3. Select the Ethernet connection type, and click Create.
4. On the Ethernet tab, select a device and, optionally, further Ethernet-related settings.
5. On the IPv4 Settings tab, configure the IPv4 settings. For example, set a static IPv4 address, network mask, default gateway, and DNS server:
6. On the IPv6 Settings tab, configure the IPv6 settings. For example, set a static IPv6 address, network mask, default gateway, and DNS server:
7. Save the connection.
8. Close nm-connection-editor.

Procedure

1. To create a Wi-Fi connection profile with static IP configuration:

   ~]$ nmcli con add con-name MyCafe ifname wlan0 type wifi ssid MyCafe ` `ip4 192.168.100.101/24 gw4 192.168.100.1

2. Set a DNS server. For example, to set 192.160.100.1 as the DNS server:

   ~]$ nmcli con modify con-name MyCafe ipv4.dns "192.160.100.1"

3. Optionally, set a DNS search domain. For example, to set the search domain to example.com:

   ~]$ nmcli con modify con-name MyCafe ipv4.dns-search "example.com"

4. To check a specific property, for example mtu:

   ~]$ nmcli connection show id MyCafe | grep mtu
   802-11-wireless.mtu:                     auto

5. To change the property of a setting:

   ~]$ nmcli connection modify id MyCafe 802-11-wireless.mtu 1350

6. To verify the change:

   ~]$ nmcli connection show id MyCafe | grep mtu
   802-11-wireless.mtu:                     1350

Procedure

1. Press the Super key to enter the Activities Overview, type Wi-Fi and press Enter. In the left-hand-side menu entry you see the list of available networks.

2. Select the gear wheel icon to the right of the Wi-Fi connection name that you want to edit, and the editing connection dialog appears. The Details menu window shows the connection details where you can make further configuration.

   Options

   1. If you select Connect automatically, NetworkManager auto-connects to this connection whenever NetworkManager detects that it is available. If you do not want NetworkManager to connect automatically, clear the check box. Note that when the check box is clear, you have to select that connection manually in the network connection icon’s menu to cause it to connect.
   2. To make a connection available to other users, select the Make available to other users check box.

   3. You can also control the background data usage. If you leave Restrict background data usage unspecified (default), then NetworkManager tries to download data that you are actively using. Otherwise, select the check box and NetworkManager sets the connection as metered, and applies restriction on the background data usage.

      Note

      To delete a Wi-Fi connection, click the Forget Connection red box.

3. Select the Identity menu entry to see the basic configuration options.

   SSID — The Service Set Identifier (SSID) of the access point (AP).

   BSSID — The Basic Service Set Identifier (BSSID) is the MAC address, also known as a hardware address, of the specific wireless access point you are connecting to when in Infrastructure mode. This field is blank by default, and you are able to connect to a wireless access point by SSID without having to specify its BSSID. If the BSSID is specified, it will force the system to associate to a specific access point only. For ad-hoc networks, the BSSID is generated randomly by the mac80211 subsystem when the ad-hoc network is created. It is not displayed by NetworkManager.

   MAC address — The MAC address allows you to associate a specific wireless adapter with a specific connection (or connections).

   Cloned Address — A cloned MAC address to use in place of the real hardware address. Leave blank unless required.

4. For further IP address configuration , select the IPv4 and IPv6 menu entries.

   By default, both IPv4 and IPv6 are set to automatic configuration depending on current network settings. This means that addresses such as the local IP address, DNS address, and other settings will be detected automatically when the interface connects to a network. If a DHCP server assigns the IP configuration in this network, this is sufficient, but you can also provide static configuration in the IPv4 and IPv6 Settings. In the IPv4 and IPv6 menu entries, you can see the following settings:

   • IPv4 Method

     • Automatic (DHCP) — Choose this option if the network you are connecting to uses Router Advertisements (RA) or a DHCP server to assign dynamic IP addresses. You can see the assigned IP address in the Details menu entry.
     • 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.
     • Disable — IPv4 is disabled for this connection.

   • DNS

     If Automatic is ON, and no DHCP server is available that assigns DNS servers to this connection, switch it to OFF to enter the IP address of a DNS server separating the IPs by comma.

   • Routes

     Note that in the Routes section, when Automatic is ON, routes from Router Advertisements (RA) or 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, sub-net, 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, sub-net, 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.

     Alternatively, to configure IPv6 settings in a Wi-Fi 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.
     • Disable — IPv6 is disabled for this connection.
   • The DNS, Routes, Use this connection only for resources on its network fields are common to IPv4 settings.

5. To configure Security settings in a Wi-Fi connection, select the Security menu entry. The following configuration options are available:

   • Security

     • None — Do not encrypt the Wi-Fi connection.
     • WEP 40/128-bit Key — Wired Equivalent Privacy (WEP), from the IEEE 802.11 standard. Uses a single pre-shared key (PSK).

     • WEP 128-bit Passphrase — An MD5 hash of the passphrase to derive a WEP key.

       Warning

       If the Wi-Fi use no encryption, WEP, or WPA, do not use the network because it is insecure and everyone can read the data you send over this network.

     • LEAP — Lightweight Extensible Authentication Protocol, from Cisco Systems.
     • Dynamic WEP (802.1X) — WEP keys are changed dynamically.
     • WPA & WPA2 Personal — Wi-Fi Protected Access (WPA), from the draft IEEE 802.11i standard. A replacement for WEP. Wi-Fi Protected Access II (WPA2), from the 802.11i-2004 standard. Personal mode uses a pre-shared key (WPA-PSK).
     • WPA & WPA2 Enterprise — WPA for use with a RADIUS authentication server to provide IEEE 802.1X network access control.
   • Password — Enter the password to be used in the authentication process.
6. Once you have finished the configuration, click the Apply button to save it.

Procedure

1. To refresh the available Wi-Fi connection list:

   ~]$ nmcli device wifi rescan

2. To view the available Wi-Fi access points:

   ~]$ nmcli dev wifi list
   
   IN-USE  SSID      MODE   CHAN  RATE        SIGNAL  BARS  SECURITY
   ...
           MyCafe    Infra  3     405 Mbit/s  85      ▂▄▆█  WPA1 WPA2

3. To connect to a Wi-Fi connection using nmcli:

   ~]$ nmcli dev wifi connect SSID-Name password wireless-password

   For example:

   ~]$ nmcli dev wifi connect MyCafe password wireless-password

   Note that if you want to disable the Wi-Fi state:

   ~]$ nmcli radio wifi off

Procedure

1. Open the GNOME Shell network connection icon menu from the top right-hand corner of the screen.
2. Select Wi-Fi Not Connected.
3. Click the Select Network option.

4. Click the name of the network to which you want to connect, and then click Connect.

   Note that if you do not see the network, the network might be hidden.

5. If the network is protected by a password or encryption keys are required, enter the password and click Connect.

   Note that if you do not know the password, contact the administrator of the Wi-Fi network.

6. If the connection is successful, the name of the network is visible in the connection icon menu and the wireless indicator is on the top right-hand corner of the screen.

Procedure

1. For a wireless connection, set the authenticated key-mgmt (key management) protocol. It configures the keying mechanism for a secure wifi connection.
2. Configure the 802-1x authentication settings.

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:

   $ sudo 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:

   $ sudo nmcli connection modify example ipv6.gateway "2001:db8::1"

2. Restart the network connection for changes to take effect. For example, to restart the example connection using the command line:

   $ sudo 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 dev example proto static metric 100 pref medium

Procedure

1. Open the nmcli interactive mode for the required connection. For example, to open the nmcli interactive mode for the example connection:

   $ sudo 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:

   nmcli> set ipv6.gateway 2001:db8::1

3. Optionally, verify that the default gateway was set correctly:

   nmcli> print
   ...
   ipv4.gateway:                           192.0.2.1
   ...
   ipv6.gateway:                           2001:db8::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 dev example proto static metric 100 pref medium

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:

      

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. Open the IPv6 tab.

   2. Enter the address in the gateway field next to the IP range the gateway’s address is within:

      

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:

   $ sudo 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 dev example proto static metric 100 pref medium

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:

      

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. Open the IPv6 tab.

   2. Enter the address in the gateway field next to the IP range the gateway’s address is within:

      

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 dev example proto static metric 100 pref medium

Procedure

1. Add the static route to the example connection:

   $ sudo nmcli connection modify example +ipv4.routes "192.0.2.0/24 198.51.100.1"

   To set multiple routes in one step, pass the individual routes comma-separated to the command. For example, to add a route to the 192.0.2.0/24 and 203.0.113.0/24 networks, both routed through the 198.51.100.1 gateway, enter:

   $ sudo nmcli connection modify example +ipv4.routes "192.0.2.0/24 198.51.100.1, 203.0.113.0/24 198.51.100.1"

2. Optionally, verify that the routes were added correctly to the configuration:

   $ nmcli connection show example
   ...
   ipv4.routes:        { ip = 192.0.2.1/24, nh = 198.51.100.1 }
   ...

3. Restart the network connection:

   $ sudo nmcli connection up example

   Warning

   Restarting the connection briefly disrupts connectivity on that interface.

4. Optionally, verify that the route is active:

   $ ip route
   ...
   192.0.2.0/24 via 198.51.100.1 dev example proto static metric 100

Procedure

1. Open the IPv4 tab.
2. Optionally, 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.

3. Enter the address, netmask, gateway, and optionally a metric value:

   

4. Click Apply.

5. 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.

6. Optionally, verify that the route is active:

   $ ip route
   ...
   192.0.2.0/24 via 198.51.100.1 dev example proto static metric 100

Procedure

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

   $ nm-connection-editor

2. Select the example connection and click the gear wheel icon to edit the existing connection.
3. Open the IPv4 tab.
4. Click the Routes button.

5. Click the Add button and enter the address, netmask, gateway, and optionally a metric value.

   

6. Click OK.
7. Click Save.

8. Restart the network connection for changes to take effect. For example, to restart the example connection using the command line:

   $ sudo nmcli connection up example

9. Optionally, verify that the route is active:

   $ ip route
   ...
   192.0.2.0/24 via 198.51.100.1 dev example proto static metric 100

Procedure

1. Open the nmcli interactive mode for the example connection:

   $ sudo nmcli connection edit example

2. Add the static route:

   nmcli> set ipv4.routes 192.0.2.0/24 198.51.100.1

3. Optionally, verify that the routes were added correctly to the configuration:

   nmcli> print
   ...
   ipv4.routes:        { ip = 192.0.2.1/24, nh = 198.51.100.1 }
   ...

   The ip attribute displays the network to route and the nh attribute the gateway (next hop).

4. Save the configuration:

   nmcli> save persistent

5. Restart the network connection:

   nmcli> activate example

   Warning

   When you restart the connection, all connections currently using this connection will be temporarily interrupted.

6. Leave the nmcli interactive mode:

   nmcli> quit

7. Optionally, verify that the route is active:

   $ ip route
   ...
   192.0.2.0/24 via 198.51.100.1 dev example proto static metric 100

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 following list describes the options of the command:

   • 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 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 "0.0.0.0/1 192.0.2.2 table=5000, 128.0.0.0/1 192.0.2.2 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.

   Note

   The nmcli utility does not support using 0.0.0.0/0 for the default gateway in ipv4.gateway. To work around this problem, the command creates separate routes for both the 0.0.0.0/1 and 128.0.0.0/1 subnets, which covers also the full IPv4 address space.

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 src=192.0.2.1 table=5000" ipv4.routing-rules "priority 5 from 10.0.0.0/24 table 5000" connection.zone internal

   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 route 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 internal

Verification steps

1. On a RHEL host in the internal workstation subnet:

   1. Install the traceroute package:

      # yum 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:

      # yum 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.

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
   0.0.0.0/1 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
   128.0.0.0/1 via 192.0.2.2 dev enp1s0 proto static metric 100

3. Display which interfaces are assigned to which firewall zones:

   # firewall-cmd --get-active-zones
   external
     interfaces: enp1s0 enp7s0
   internal
     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
     ...

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.

      

5. On the IPv4 Settings tab, configure the IPv4 settings. For example, set a static IPv4 address, network mask, default gateway, and DNS server:
6. On the IPv6 Settings tab, configure the IPv6 settings. For example, set a static IPv6 address, network mask, default gateway, and DNS server:
7. Click Save to save the VLAN connection.
8. Close nm-connection-editor.

9. Optionally, 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 fe80::8dd7:9030:6f8e:89e6/64 scope link noprefixroute
          valid_lft forever preferred_lft forever

Procedure

1. Optionally, display the available network interfaces:

   # ip address show
   1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 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
       inet6 ::1/128 scope host
          valid_lft forever preferred_lft forever
   2: enp1s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP group default qlen 1000
       link/ether 52:54:00:d5:e0:fb brd ff:ff:ff:ff:ff:ff

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 802-3-ethernet.mtu 2000

4. Configure the IPv4 settings. For example, 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'
   # 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

5. Configure the IPv6 settings. For example, 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::1/32'
   # nmcli connection modify vlan10 ipv6.gateway '2001:db8::fffe'
   # nmcli connection modify vlan10 ipv6.dns '2001:db8::fffd'
   # nmcli connection modify vlan10 ipv6.method manual

6. Optionally, 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 fe80::8dd7:9030:6f8e:89e6/64 scope link noprefixroute
          valid_lft forever preferred_lft forever

Procedure

1. Create a bridge interface. For example, to create the bridge interface named bridge0, enter:

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

2. Configure the IPv4 settings. For example, to set a static IPv4 address, network mask, default gateway, DNS server, and DNS search domain of the bridge0 connection, enter:

   # nmcli connection modify bridge0 ipv4.addresses '192.0.2.1/24'
   # nmcli connection modify bridge0 ipv4.gateway '192.0.2.254'
   # nmcli connection modify bridge0 ipv4.dns '192.0.2.253'
   # nmcli connection modify bridge0 ipv4.dns-search 'example.com'
   # nmcli connection modify bridge0 ipv4.method manual

3. Configure the IPv6 settings. For example, to set a static IPv6 address, network mask, default gateway, DNS server, and DNS search domain of the bridge0 connection, enter:

   # nmcli connection modify bridge0 ipv6.addresses '2001:db8::1/32'
   # nmcli connection modify bridge0 ipv6.gateway '2001:db8::fffe'
   # nmcli connection modify bridge0 ipv6.dns '2001:db8::fffd'
   # nmcli connection modify bridge0 ipv6.dns-search 'example.com'
   # nmcli connection modify bridge0 ipv6.method manual

4. Optionally, 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.

5. Optionally, display the network interfaces, and note the names of the interfaces you want to add to the bridge as a slave in the next step:

   # nmcli device
   DEVICE  TYPE      STATE         CONNECTION
   enp1s0  ethernet  connected     enp1s0
   enp7s0  ethernet  disconnected  --
   enp8s0  ethernet  disconnected  --
   lo      loopback  unmanaged     --

6. Assign the port interfaces to the bridge’s connection. For example, to add the interfaces named enp7s0 and enp8s0 to the bridge0 connection, enter:

   # 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

7. Activate the connection. For example, to activate the bridge0 connection, enter:

   # nmcli connection up bridge0

8. Verify that the slave devices are connected, and the CONNECTION column displays the slave’s connection name:

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

   Red Hat Enterprise Linux activates master and slave devices when the system boots. By activating any slave connection, the master is also activated. However, in this case, only one slave connection is activated. By default, activating the master does not automatically activate the slaves. However, you can enable this behavior by setting:

   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

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.

   1. Optionally, set the name of the bridge interface in the Interface name field.

   2. Click the Add button to add a network interface as a slave 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 slave device.
      3. In the Device field on the Ethernet tab, select the network interface you want to add as a slave to the bridge.
      4. Click Save.

   3. Repeat the previous step for each interface you want to add to the bridge.

      

   4. Optionally, configure further bridge settings, such as Spanning Tree Protocol (STP) options.
4. On the IPv4 Settings tab, configure the IPv4 settings. For example, set a static IPv4 address, network mask, default gateway, DNS server, and DNS search domain:
5. On the IPv6 Settings tab, configure the IPv6 settings. For example, set a static IPv6 address, network mask, default gateway, DNS server, and DNS search domain:
6. Save the bridge connection.
7. Close nm-connection-editor.

Procedure

1. Install the teamd and NetworkManager-team packages:

   # yum install teamd NetworkManager-team

Procedure

1. Create the team interface. For example, to create a team interface that uses the activebackup runner and both the interface and connection named team0, enter:

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

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

   # 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 quotes. 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. Configure the IPv4 settings. For example, to set a static IPv4 address, network mask, default gateway, DNS server, and DNS search domain the team0 connection, enter:

   # nmcli connection modify team0 ipv4.addresses '192.0.2.1/24'
   # nmcli connection modify team0 ipv4.gateway '192.0.2.254'
   # nmcli connection modify team0 ipv4.dns '192.0.2.253'
   # nmcli connection modify team0 ipv4.dns-search 'example.com'
   # nmcli connection modify team0 ipv4.method manual

4. Configure the IPv6 settings. For example, to set a static IPv6 address, network mask, default gateway, DNS server, and DNS search domain of the team0 connection, enter:

   # nmcli connection modify team0 ipv6.addresses '2001:db8::1/32'
   # nmcli connection modify team0 ipv6.gateway '2001:db8::fffe'
   # nmcli connection modify team0 ipv6.dns '2001:db8::fffd'
   # nmcli connection modify team0 ipv6.dns-search 'example.com'
   # nmcli connection modify team0 ipv6.method manual

5. Optionally, display the network interfaces, and note the names of the interfaces you want to add to the team in the next step:

   # nmcli device
   DEVICE  TYPE      STATE         CONNECTION
   enp1s0  ethernet  connected     enp1s0
   enp7s0  ethernet  disconnected  --
   enp8s0  ethernet  disconnected  --
   lo      loopback  unmanaged     --

   Important

   You can only use network interfaces in a team that are not assigned to any connection. In the above example, you can only use the enp7s0 and enp8s0 interfaces.

6. Assign the port interfaces to the team’s connection. For example, to add the interfaces named enp7s0 and enp8s0 to the team0 connection:

   # 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

7. Activate the connection. For example, to activate the team0 connection:

   # nmcli connection up team0

8. Optionally, 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 the example, both ports are up.

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. Optionally, set the name of the team interface in the Interface name field.

   2. Click the Add button to add a network interface as a slave to the team.

      1. Select the connection type of the interface. For example, select Ethernet for a wired connection.
      2. Optionally, set a connection name for the slave device.

      3. In the Device field on the Ethernet tab, select the network interface you want to add as a slave to the team.

         Important

         You can only use network interfaces in a team that are not configured.

      4. Click Save.

   3. Repeat the previous step for each interface you want to add to the team.

      

   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 link watcher and its optional settings.
      3. Click OK.
5. On the IPv4 Settings tab, configure the IPv4 settings. For example, set a static IPv4 address, network mask, default gateway, DNS server, and DNS search domain:
6. On the IPv6 Settings tab, configure the IPv6 settings. For example, set a static IPv6 address, network mask, default gateway, DNS server, and DNS search domain:
7. Click Save to save the team connection.
8. Close nm-connection-editor.

9. Optionally, 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

Procedure

1. Create a bond interface. For example, to create a bond interface that uses the active-backup mode and both the interface and the connection are named bond0, enter:

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

   To additionally set a Media Independent Interface (MII) monitoring interval, add the miimon=interval option to the bond.options property. For example, to use the same command but, additionally, set the MII monitoring interval to 1000 milliseconds (1 second), enter:

   # nmcli connection add type bond con-name bond0 ifname bond0 bond.options "mode=active-backup,miimon=1000"

2. Configure the IPv4 settings. For example, to set a static IPv4 address, network mask, default gateway, DNS server, and DNS search domain to the bond0 connection, enter:

   # 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. For example, to set a static IPv6 address, network mask, default gateway, DNS server, and DNS search domain to the bond0 connection, enter:

   # nmcli connection modify bond0 ipv6.addresses '2001:db8::1/32
   # nmcli connection modify bond0 ipv6.gateway '2001:db8::fffe'
   # nmcli connection modify bond0 ipv6.dns '2001:db8::fffd'
   # nmcli connection modify bond0 ipv6.dns-search 'example.com'
   # nmcli connection modify bond0 ipv6.method manual

4. Optionally, display the network interfaces, and note names of interfaces you plan to add to the bond:

   # # nmcli device
   DEVICE  TYPE      STATE         CONNECTION
   enp1s0  ethernet  connected     enp1s0
   enp7s0  ethernet  disconnected  --
   enp8s0  ethernet  disconnected  --
   lo      loopback  unmanaged     --

5. Assign port interfaces to the bond’s connection. For example, to add the interfaces named enp7s0 and enp8s0 to the bond0 connection:

   # 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

6. Activate the connection. For example, to activate the bond0 connection:

   # nmcli connection up bond0

7. Verify that the slave devices are connected, and the CONNECTION column displays the slave’s connection name:

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

   Red Hat Enterprise Linux activates master and slave devices when the system boots. By activating any slave connection, the master is also activated. However, in this case, only one slave connection is activated. By default, activating the master does not automatically activate the slaves. However, you can enable this behavior by setting:

   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

8. Optionally, display the status of the bond:

   # cat /proc/net/bonding/bond0
   Ethernet Channel Bonding Driver: v3.7.1 (April 27, 2011)
   
   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
   
   Slave Interface: enp7s0
   MII Status: up
   Speed: Unknown
   Duplex: Unknown
   Link Failure Count: 0
   Permanent HW addr: 52:54:00:d5:e0:fb
   Slave queue ID: 0
   
   Slave Interface: enp8s0
   MII Status: up
   Speed: Unknown
   Duplex: Unknown
   Link Failure Count: 0
   Permanent HW addr: 52:54:00:b2:e2:63
   Slave queue ID: 0

   In the example, both ports are up.

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. Optionally, set the name of the bond interface in the Interface name field.

   2. Click the Add button to add a network interface as a slave to the bond.

      1. Select the connection type of the interface. For example, select Ethernet for a wired connection.
      2. Optionally, set a connection name for the slave device.

      3. In the Device field on the Ethernet tab, select the network interface you want to add as a slave to the bond.

         Important

         You can only use network 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:

      

   4. Optionally, set other options, such as the Media Independent Interface (MII) monitoring interval.

5. On the IPv4 Settings tab, configure the IPv4 settings. For example, set a static IPv4 address, network mask, default gateway, DNS server, and DNS search domain:

   

6. On the IPv6 Settings tab, configure the IPv6 settings. For example, set a static IPv6 address, network mask, default gateway, DNS server, and DNS search domain:

   

7. Click Save to save the bond connection.
8. Close nm-connection-editor.

9. Optionally, display the status of the bond:

   $ cat /proc/net/bonding/_bond0_
   Ethernet Channel Bonding Driver: v3.7.1 (April 27, 2011)
   
   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
   
   Slave Interface: enp7s0
   MII Status: up
   Speed: Unknown
   Duplex: Unknown
   Link Failure Count: 0
   Permanent HW addr: 52:54:00:d5:e0:fb
   Slave queue ID: 0
   
   Slave Interface: enp8s0
   MII Status: up
   Speed: Unknown
   Duplex: Unknown
   Link Failure Count: 0
   Permanent HW addr: 52:54:00:b2:e2:63
   Slave queue ID: 0

   In the example, both ports are up.

Procedure

1. 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 username and password, or secret (PSK).

     The following configuration settings are available under the Advanced section:

     Figure 18.1. Advanced options of a VPN connection

     
     Warning

     When configuring an IPsec based VPN connection using the gnome-control-center application, the Advanced dialog will only display the configuration, but will not allow doing any change. 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 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 throught 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 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.

2. For further configuration, select the IPv4 menu entry:

   • IPv4 Method

     • Automatic (DHCP) — Choose this option if the network you are connecting to uses Router Advertisements (RA) or 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.
     • Disable — IPv4 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 Router Advertisements (RA) or 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, sub-net, 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, sub-net, 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 will be routed over the connection.

3. Alternatively, 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.

     • Disable — IPv6 is disabled for this connection.

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

4. 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.
5. Switch the profile to ON to active the VPN connection.

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.

      

   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.

   

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

Procedure

1. Edit the /etc/NetworkManager/NetworkManager.conf file:

   1. Add the [connection] section, if it does not exist:

      [connection]

   2. Add the custom default values to the [connection] section. For example, to set the new default for both IPv4 and IPv6 to 200, add:

      ipv4.dns-priority=200
      ipv6.dns-priority=200

      You can set the parameters to a value between -2147483647 and 2147483647. Note that setting the parameters to 0 enables the built-in defaults (50 for VPN connections and 100 for other connections).

2. Reload the NetworkManager service:

   # systemctl reload NetworkManager

Procedure

1. Optionally, display the available connections:

   # nmcli connection show
   NAME           UUID                                  TYPE      DEVICE
   Example_con_1  d17ee488-4665-4de2-b28a-48befab0cd43  ethernet  enp1s0
   Example_con_2  916e4f67-7145-3ffa-9f7b-e7cada8f6bf7  ethernet  enp7s0
   ...

2. Set the ipv4.dns-priority and ipv6.dns-priority parameters. For example, to set both parameters to 10 for the Example_con_1 connection:

   # nmcli connection modify Example_con_1 ipv4.dns-priority 10 ipv6.dns-priority 10

3. Optionally, repeat the previous step for other connections.

4. Re-activate the connection you updated:

   # nmcli connection up Example_con_1

Procedure

1. To configure an interface named em1 with dynamic network settings using ifcfg files, create a file with the name ifcfg-em1 in the /etc/sysconfig/network-scripts/ directory that contains:

   DEVICE=em1
   BOOTPROTO=dhcp
   ONBOOT=yes

2. To configure an interface to send a different host name to the DHCP server, add the following line to the ifcfg file:

   DHCP_HOSTNAME=hostname

3. To configure an interface to send a different fully qualified domain name (FQDN) to the DHCP server, add the following line to the ifcfg file:

   DHCP_FQDN=fully.qualified.domain.name

   Note

   Only one directive, either DHCP_HOSTNAME or DHCP_FQDN, should be used in a given ifcfg file. In case both DHCP_HOSTNAME and DHCP_FQDN are specified, only the latter is used.

4. To configure an interface to use particular DNS servers, add the following lines to the ifcfg file:

     PEERDNS=no
     DNS1=ip-address
     DNS2=ip-address

   where ip-address is the address of a DNS server. This will cause the network service to update /etc/resolv.conf with the specified DNS servers specified. Only one DNS server address is necessary, the other is optional.

1. As an example, modify the ifcfg file with the following row, which will make the connection available only to the users listed:

   USERS="joe bob alice"

Procedure

1. Optionally, display the list of network connections:

   # nmcli connection show
   NAME    UUID                                  TYPE      DEVICE
   Example 7a7e0151-9c18-4e6f-89ee-65bb2d64d365  ethernet  enp1s0
   ...

2. Set the ipv6.method parameter of the connection to disabled:

   # nmcli connection modify Example ipv6.method "disabled"

3. Restart the network connection:

   # nmcli connection up Example

Verification steps

1. Enter the ip address show command to display the IP settings of the device:

   # ip address show enp1s0
   2: enp1s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP group default qlen 1000
       link/ether 52:54:00:6b:74:be brd ff:ff:ff:ff:ff:ff
       inet 192.0.2.1/24 brd 192.10.2.255 scope global noprefixroute enp1s0
          valid_lft forever preferred_lft forever

   If no inet6 entry is displayed, IPv6 is disabled on the device.

2. Verify that the /proc/sys/net/ipv6/conf/enp1s0/disable_ipv6 file now contains the value 1:

   # cat /proc/sys/net/ipv6/conf/enp1s0/disable_ipv6
   1

   The value 1 means that IPv6 is disabled for the device.

Procedure

1. Create the /etc/NetworkManager/conf.d/90-dns-none.conf file with the following content:

   [main]
   dns=none

2. Reload the NetworkManager service:

   # systemctl reload NetworkManager

   Note

   After you reload the service, NetworkManager no longer updates the /etc/resolv.conf file. However, the last contents of the file are preserved.

3. Optionally, remove the Generated by NetworkManager comment from /etc/resolv.conf to avoid confusion.

Verification steps

1. Edit the /etc/resolv.conf file and manually update the configuration.

2. Reload the NetworkManager service:

   # systemctl reload NetworkManager

3. Display the /etc/resolv.conf file:

   # cat /etc/resolv.conf

   If you successfully disabled DNS processing, NetworkManager did not override the manually configured settings.

Procedure

1. Create a file, such as /etc/resolv.conf.manually-configured, and add the DNS configuration for your environment to it. Use the same parameters and syntax as in the original /etc/resolv.conf.

2. Remove the /etc/resolv.conf file:

   # rm /etc/resolv.conf

3. Create a symbolic link named /etc/resolv.conf that refers to /etc/resolv.conf.manually-configured:

   # ln -s /etc/resolv.conf.manually-configured /etc/resolv.conf

Procedure

1. To ignore link negotiation, set the following parameters:

   ~]# nmcli connection modify connection_name 802-3-ethernet.auto-negotiate no 802-3-ethernet.speed 0 802-3-ethernet.duplex ""

   Note, that the auto-negotiation parameter is not disabled even if the speed and duplex parameters are not set and the auto-negotiation parameter is set to no.

2. To enforce the auto-negotiation activation, enter the following command:

   ~]# nmcli connection modify connection_name 802-3-ethernet.auto-negotiate yes 802-3-ethernet.speed 0 802-3-ethernet.duplex ""

   That allows to negotiate all the available speed and duplex modes supported by the NIC.

   You can also enable auto-negotiation while advertising and allowing only one speed/duplex mode. This can be useful if you want to enforce 1000BASE-T and 10GBASE-T Ethernet link configuration, as these standards mandate auto-negotiation enabled. To enforce 1000BASE-T standard:

   ~]# nmcli connection modify connection_name 802-3-ethernet.auto-negotiate yes 802-3-ethernet.speed 1000 802-3-ethernet.duplex full

3. To manually set the speed and duplex link settings, enter the following command:

   ~]# nmcli connection modify connection_name 802-3-ethernet.auto-negotiate no 802-3-ethernet.speed [speed in Mbit/s] 802-3-ethernet.duplex [full|half]

Procedure

1. For example, to enable the RX offload feature and disable TX offload in the enp0s1 connection profile, enter:

   # nmcli con modify enp0s1 ethtool.feature-rx on ethtool.feature-tx off

   This command explicitly enables RX offload and disables TX offload.

2. To remove the setting of an offload feature that you previously enabled or disabled, set the feature’s parameter to ignore. For example, to remove the configuration for TX offload, enter:

   # nmcli con modify enp0s1 ethtool.feature-tx ignore

3. Reactivate the network profile:

   # nmcli connection up enp0s1

Verification steps

1. Use the ethtool -k command to display the current offload features of a network device:

   # ethtool -k network_device

Procedure

1. Create a CAK/CKN pair. For example, the following command generates a 16-byte key in hexadecimal notation:

   ~]$ dd if=/dev/urandom count=16 bs=1 2> /dev/null | hexdump -e '1/2 "%02x"'

2. Create the wpa_supplicant.conf configuration file and add the following lines to it:

   ctrl_interface=/var/run/wpa_supplicant
   eapol_version=3
   ap_scan=0
   fast_reauth=1
   
   network={
       key_mgmt=NONE
       eapol_flags=0
       macsec_policy=1
   
       mka_cak=0011... # 16 bytes hexadecimal
       mka_ckn=2233... # 32 bytes hexadecimal
   }

   Use the values from the previous step to complete the mka_cak and mka_ckn lines in the wpa_supplicant.conf configuration file.

   For more information, see the wpa_supplicant.conf(5) man page.

3. Assuming you are using wlp61s0 to connect to your network, start wpa_supplicant using the following command:

   ~]# wpa_supplicant -i wlp61s0 -Dmacsec_linux -c wpa_supplicant.conf

Procedure

1. Start and enable the systemd-resolved service:

   # systemctl --now enable systemd-resolved

2. Edit the /etc/NetworkManager/NetworkManager.conf file, and set the following entry in the [main] section:

   dns=systemd-resolved

3. Reload the NetworkManager service:

   # systemctl reload NetworkManager

Verification steps

1. Verify that the nameserver entry in the /etc/resolv.conf file refers to 127.0.0.53:

   # cat /etc/resolv.conf
   nameserver 127.0.0.53

2. Verify that the systemd-resolved service listens on port 53 on the local IP address 127.0.0.53:

   # netstat -tulpn | grep "127.0.0.53:53"
   tcp   0   0 127.0.0.53:53   0.0.0.0:*   LISTEN   1050/systemd-resolv
   udp   0   0 127.0.0.53:53   0.0.0.0:*            1050/systemd-resolv

1. The kernel must receive the data.
2. The kernel must determine that the data belongs to the application.
3. The kernel wakes up the application.
4. The kernel waits for the application to perform a system call into the kernel.
5. The application copies the data from the kernel’s own internal memory space into the buffer provided by the application.