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Chapter 6. Configuring an Ethernet connection

This section describes different ways how to configure an Ethernet connection with static and dynamic IP addresses.

6.1. Configuring a static Ethernet connection using nmcli

This procedure describes adding an Ethernet connection with the following settings using the nmcli utility:

  • 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

Procedure

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

    # nmcli connection add con-name Example-Connection ifname enp7s0 type ethernet

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

  2. Set the IPv4 address:

    # nmcli connection modify Example-Connection ipv4.addresses 192.0.2.1/24
  3. Set the IPv6 address:

    # nmcli connection modify Example-Connection ipv6.addresses 2001:db8:1::1/64
  4. 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
  5. 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:db8:1::fffe
  6. 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:db8:1::ffbb"

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

  7. 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
  8. Activate 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
    ...
  3. Use the ping utility to verify that this host can send packets to other hosts.

    • Ping an IP address in the same subnet.

      For IPv4:

      # ping 192.0.2.3

      For IPv6:

      # ping 2001:db8:1::2

      If the command fails, verify the IP and subnet settings.

    • Ping an IP address in a remote subnet.

      For IPv4:

      # ping 198.162.3.1

      For IPv6:

      # ping 2001:db8:2::1
      • If the command fails, ping the default gateway to verify settings.

        For IPv4:

        # ping 192.0.2.254

        For IPv6:

        # ping 2001:db8:1::fff3
  4. Use the host utility to verify that name resolution works. For example:

    # host client.example.com

    If the command returns any error, such as connection timed out or no servers could be reached, verify your DNS settings.

Troubleshooting steps

  1. If the connection fails or if the network interface switches between an up and down status:

    • Make sure 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 the server is connected to.
    • 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 NetworkManager duplicates a connection after restart of NetworkManager service

Additional resources

6.2. Configuring a static Ethernet connection using the nmcli interactive editor

This procedure describes adding an Ethernet connection with the following settings using the nmcli interactive mode:

  • 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

Procedure

  1. To add a new NetworkManager connection profile for the Ethernet connection, and starting the interactive mode, enter:

    # nmcli connection edit type ethernet con-name Example-Connection
  2. Set the network interface:

    nmcli> set connection.interface-name enp7s0
  3. Set the IPv4 address:

    nmcli> set ipv4.addresses 192.0.2.1/24
  4. Set the IPv6 address:

    nmcli> set ipv6.addresses 2001:db8:1::1/64
  5. Set the IPv4 and IPv6 connection method to manual:

    nmcli> set ipv4.method manual
    nmcli> set ipv6.method manual
  6. Set the IPv4 and IPv6 default gateways:

    nmcli> set ipv4.gateway 192.0.2.254
    nmcli> set ipv6.gateway 2001:db8:1::fffe
  7. Set the IPv4 and IPv6 DNS server addresses:

    nmcli> set ipv4.dns 192.0.2.200
    nmcli> set ipv6.dns 2001:db8:1::ffbb

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

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

    nmcli> set ipv4.dns-search example.com
    nmcli> set ipv6.dns-search example.com
  9. Save and activate the connection:

    nmcli> save persistent
    Saving the connection with 'autoconnect=yes'. That might result in an immediate activation of the connection.
    Do you still want to save? (yes/no) [yes] yes
  10. Leave the interactive mode:

    nmcli> quit

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

    • Ping an IP address in the same subnet.

      For IPv4:

      # ping 192.0.2.3

      For IPv6:

      # ping 2001:db8:1::2

      If the command fails, verify the IP and subnet settings.

    • Ping an IP address in a remote subnet.

      For IPv4:

      # ping 198.162.3.1

      For IPv6:

      # ping 2001:db8:2::1
      • If the command fails, ping the default gateway to verify settings.

        For IPv4:

        # ping 192.0.2.254

        For IPv6:

        # ping 2001:db8:1::fff3
  4. Use the host utility to verify that name resolution works. For example:

    # host client.example.com

    If the command returns any error, such as connection timed out or no servers could be reached, verify your DNS settings.

Troubleshooting steps

  1. If the connection fails or if the network interface switches between an up and down status:

    • Make sure 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 the server is connected to.
    • 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 NetworkManager duplicates a connection after restart of NetworkManager service

Additional resources

6.3. Configuring a static Ethernet connection using nmstatectl

This procedure describes how to configure an Ethernet connection for the enp7s0 device with the following settings using the nmstatectl utility:

  • 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

The nmstatectl utility 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.

The procedure defines the interface configuration in YAML format. Alternatively, you can also specify the configuration in JSON format.

Prerequisites

  • The nmstate package is installed.

Procedure

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

    ---
    interfaces:
    - name: enp7s0
      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: enp7s0
      - destination: ::/0
        next-hop-address: 2001:db8:1::fffe
        next-hop-interface: enp7s0
    dns-resolver:
      config:
        search:
        - example.com
        server:
        - 192.0.2.200
        - 2001:db8:1::ffbb
  2. Apply the settings to the system:

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

Verification steps

  1. Display the status of the devices and connections:

    # nmcli device status
    DEVICE      TYPE      STATE      CONNECTION
    enp7s0      ethernet  connected  enp7s0
  2. Display all settings of the connection profile:

    # nmcli connection show enp7s0
    connection.id:              enp7s0
    connection.uuid:            b6cdfa1c-e4ad-46e5-af8b-a75f06b79f76
    connection.stable-id:       --
    connection.type:            802-3-ethernet
    connection.interface-name:  enp7s0
    ...
  3. Display the connection settings in YAML format:

    # nmstatectl show enp7s0

Additional resources

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

6.4. Configuring a static Ethernet connection using RHEL System Roles with the interface name

This procedure describes how to use the Networking RHEL System Role to remotely add an Ethernet connection for the enp7s0 interface with the following settings by running an Ansible playbook:

  • 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

Run this procedure on the Ansible control node.

Prerequisites

  • The ansible-core and rhel-system-roles packages are installed on the control node.
  • If you use a different remote user than root when you run the playbook, this user has appropriate sudo permissions on the managed node.
  • The host uses NetworkManager to configure the network.

Procedure

  1. If the host on which you want to execute the instructions in the playbook is not yet inventoried, add the IP or name of this host to the /etc/ansible/hosts Ansible inventory file:

    node.example.com
  2. Create the ~/ethernet-static-IP.yml playbook with the following content:

    ---
    - name: Configure an Ethernet connection with static IP
      hosts: node.example.com
      become: true
      tasks:
      - include_role:
          name: rhel-system-roles.network
    
        vars:
          network_connections:
            - name: enp7s0
              interface_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
              state: up
  3. Run the playbook:

    • To connect as root user to the managed host, enter:

      # ansible-playbook -u root ~/ethernet-static-IP.yml
    • To connect as a user to the managed host, enter:

      # ansible-playbook -u user_name --ask-become-pass ~/ethernet-static-IP.yml

      The --ask-become-pass option makes sure that the ansible-playbook command prompts for the sudo password of the user defined in the -u user_name option.

    If you do not specify the -u user_name option, ansible-playbook connects to the managed host as the user that is currently logged in to the control node.

Additional resources

  • /usr/share/ansible/roles/rhel-system-roles.network/README.md
  • ansible-playbook(1) man page

6.5. Configuring a static Ethernet connection using RHEL System Roles with a device path

This procedure describes how to use RHEL System Roles to remotely add an Ethernet connection with static IP address for devices that match a specific device path by running an Ansible playbook.

You can identify the device path with the following command:

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

This procedure sets the following settings to the device that matches the PCI ID 0000:00:0[1-3].0 expression, but not 0000:00:02.0:

  • 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

Run this procedure on the Ansible control node.

Prerequisites

  • The ansible-core and rhel-system-roles packages are installed on the control node.
  • If you use a different remote user than root when you run the playbook, this user has appropriate sudo permissions on the managed node.
  • The host uses NetworkManager to configure the network.

Procedure

  1. If the host on which you want to execute the instructions in the playbook is not yet inventoried, add the IP or name of this host to the /etc/ansible/hosts Ansible inventory file:

    node.example.com
  2. Create the ~/ethernet-dynamic-IP.yml playbook with the following content:

    ---
    - name: Configure an Ethernet connection with dynamic IP
      hosts: node.example.com
      become: true
      tasks:
      - 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

    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.

  3. Run the playbook:

    • To connect as root user to the managed host, enter:

      # ansible-playbook -u root ~/ethernet-dynamic-IP.yml
    • To connect as a user to the managed host, enter:

      # ansible-playbook -u user_name --ask-become-pass ~/ethernet-dynamic-IP.yml

      The --ask-become-pass option makes sure that the ansible-playbook command prompts for the sudo password of the user defined in the -u user_name option.

    If you do not specify the -u user_name option, ansible-playbook connects to the managed host as the user that is currently logged in to the control node.

Additional resources

  • /usr/share/ansible/roles/rhel-system-roles.network/README.md file
  • ansible-playbook(1) man page

6.6. Configuring a dynamic Ethernet connection using nmcli

This procedure describes adding an dynamic Ethernet connection using the nmcli utility. With this setting, NetworkManager requests the IP settings for this connection from a DHCP server.

Prerequisites

  • A DHCP server is available in the network.

Procedure

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

    # nmcli connection add con-name Example-Connection ifname enp7s0 type ethernet
  2. Optionally, change the host name NetworkManager sends to the DHCP server when using the Example-Connection profile:

    # nmcli connection modify Example-Connection ipv4.dhcp-hostname Example ipv6.dhcp-hostname Example
  3. Optionally, change the client ID NetworkManager sends to an IPv4 DHCP server when using the Example-Connection profile:

    # nmcli connection modify Example-Connection ipv4.dhcp-client-id client-ID

    Note that there is no dhcp-client-id parameter for IPv6. To create an identifier for IPv6, configure the dhclient service.

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

    • Ping an IP address in the same subnet.

      For IPv4:

      # ping 192.0.2.3

      For IPv6:

      # ping 2001:db8:1::2

      If the command fails, verify the IP and subnet settings.

    • Ping an IP address in a remote subnet.

      For IPv4:

      # ping 198.162.3.1

      For IPv6:

      # ping 2001:db8:2::1
      • If the command fails, ping the default gateway to verify settings.

        For IPv4:

        # ping 192.0.2.254

        For IPv6:

        # ping 2001:db8:1::fff3
  4. Use the host utility to verify that name resolution works. For example:

    # host client.example.com

    If the command returns any error, such as connection timed out or no servers could be reached, verify your DNS settings.

Additional resources

6.7. Configuring a dynamic Ethernet connection using the nmcli interactive editor

This procedure describes adding an dynamic Ethernet connection using the interactive editor of the nmcli utility. With this setting, NetworkManager requests the IP settings for this connection from a DHCP server.

Prerequisites

  • A DHCP server is available in the network.

Procedure

  1. To add a new NetworkManager connection profile for the Ethernet connection, and starting the interactive mode, enter:

    # nmcli connection edit type ethernet con-name Example-Connection
  2. Set the network interface:

    nmcli> set connection.interface-name enp7s0
  3. Optionally, change the host name NetworkManager sends to the DHCP server when using the Example-Connection profile:

    nmcli> set ipv4.dhcp-hostname Example
    nmcli> set ipv6.dhcp-hostname Example
  4. Optionally, change the client ID NetworkManager sends to an IPv4 DHCP server when using the Example-Connection profile:

    nmcli> set ipv4.dhcp-client-id client-ID

    Note that there is no dhcp-client-id parameter for IPv6. To create an identifier for IPv6, configure the dhclient service.

  5. Save and activate the connection:

    nmcli> save persistent
    Saving the connection with 'autoconnect=yes'. That might result in an immediate activation of the connection.
    Do you still want to save? (yes/no) [yes] yes
  6. Leave the interactive mode:

    nmcli> quit

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

    • Ping an IP address in the same subnet.

      For IPv4:

      # ping 192.0.2.3

      For IPv6:

      # ping 2001:db8:1::2

      If the command fails, verify the IP and subnet settings.

    • Ping an IP address in a remote subnet.

      For IPv4:

      # ping 198.162.3.1

      For IPv6:

      # ping 2001:db8:2::1
      • If the command fails, ping the default gateway to verify settings.

        For IPv4:

        # ping 192.0.2.254

        For IPv6:

        # ping 2001:db8:1::fff3
  4. Use the host utility to verify that name resolution works. For example:

    # host client.example.com

    If the command returns any error, such as connection timed out or no servers could be reached, verify your DNS settings.

Additional resources

6.8. Configuring a dynamic Ethernet connection using nmstatectl

This procedure describes how to add an dynamic Ethernet for the enp7s0 device using the nmstatectl utility. With the settings in this procedure, NetworkManager requests the IP settings for this connection from a DHCP server.

The nmstatectl utility 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.

The procedure defines the interface configuration in YAML format. Alternatively, you can also specify the configuration in JSON format.

Prerequisites

  • The nmstate package is installed.

Procedure

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

    ---
    interfaces:
    - name: enp7s0
      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
  2. Apply the settings to the system:

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

Verification steps

  1. Display the status of the devices and connections:

    # nmcli device status
    DEVICE      TYPE      STATE      CONNECTION
    enp7s0      ethernet  connected  enp7s0
  2. Display all settings of the connection profile:

    # nmcli connection show enp7s0
    connection.id:              enp7s0_
    connection.uuid:            b6cdfa1c-e4ad-46e5-af8b-a75f06b79f76
    connection.stable-id:       --
    connection.type:            802-3-ethernet
    connection.interface-name:  enp7s0
    ...
  3. Display the connection settings in YAML format:

    # nmstatectl show enp7s0

Additional resources

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

6.9. Configuring a dynamic Ethernet connection using RHEL System Roles with the interface name

This procedure describes how to use RHEL System Roles to remotely add a dynamic Ethernet connection for the enp7s0 interface by running an Ansible playbook. With this setting, the network connection requests the IP settings for this connection from a DHCP server. Run this procedure on the Ansible control node.

Prerequisites

  • A DHCP server is available in the network.
  • The ansible-core and rhel-system-roles packages are installed on the control node.
  • If you use a different remote user than root when you run the playbook, this user has appropriate sudo permissions on the managed node.
  • The host uses NetworkManager to configure the network.

Procedure

  1. If the host on which you want to execute the instructions in the playbook is not yet inventoried, add the IP or name of this host to the /etc/ansible/hosts Ansible inventory file:

    node.example.com
  2. Create the ~/ethernet-dynamic-IP.yml playbook with the following content:

    ---
    - name: Configure an Ethernet connection with dynamic IP
      hosts: node.example.com
      become: true
      tasks:
      - include_role:
          name: rhel-system-roles.network
    
        vars:
          network_connections:
            - name: enp7s0
              interface_name: enp7s0
              type: ethernet
              autoconnect: yes
              ip:
                dhcp4: yes
                auto6: yes
              state: up
  3. Run the playbook:

    • To connect as root user to the managed host, enter:

      # ansible-playbook -u root ~/ethernet-dynamic-IP.yml
    • To connect as a user to the managed host, enter:

      # ansible-playbook -u user_name --ask-become-pass ~/ethernet-dynamic-IP.yml

      The --ask-become-pass option makes sure that the ansible-playbook command prompts for the sudo password of the user defined in the -u user_name option.

    If you do not specify the -u user_name option, ansible-playbook connects to the managed host as the user that is currently logged in to the control node.

Additional resources

  • /usr/share/ansible/roles/rhel-system-roles.network/README.md file
  • ansible-playbook(1) man page

6.10. Configuring a dynamic Ethernet connection using RHEL System Roles with a device path

This procedure describes how to use RHEL System Roles to remotely add a dynamic Ethernet connection for devices that match a specific device path by running an Ansible playbook. With dynamic IP settings, the network connection requests the IP settings for this connection from a DHCP server. Run this procedure on the Ansible control node.

You can identify the device path with the following command:

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

Prerequisites

  • A DHCP server is available in the network.
  • The ansible-core and rhel-system-roles packages are installed on the control node.
  • If you use a different remote user than root when you run the playbook, this user has appropriate sudo permissions on the managed node.
  • The host uses NetworkManager to configure the network.

Procedure

  1. If the host on which you want to execute the instructions in the playbook is not yet inventoried, add the IP or name of this host to the /etc/ansible/hosts Ansible inventory file:

    node.example.com
  2. Create the ~/ethernet-dynamic-IP.yml playbook with the following content:

    ---
    - name: Configure an Ethernet connection with dynamic IP
      hosts: node.example.com
      become: true
      tasks:
      - 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

    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.

  3. Run the playbook:

    • To connect as root user to the managed host, enter:

      # ansible-playbook -u root ~/ethernet-dynamic-IP.yml
    • To connect as a user to the managed host, enter:

      # ansible-playbook -u user_name --ask-become-pass ~/ethernet-dynamic-IP.yml

      The --ask-become-pass option makes sure that the ansible-playbook command prompts for the sudo password of the user defined in the -u user_name option.

    If you do not specify the -u user_name option, ansible-playbook connects to the managed host as the user that is currently logged in to the control node.

Additional resources

  • /usr/share/ansible/roles/rhel-system-roles.network/README.md file
  • ansible-playbook(1) man page

6.11. Configuring an Ethernet connection using control-center

Ethernet connections are the most frequently used connections types in physical or virtual machines. This section describes how to configure this connection type in the GNOME control-center:

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 device 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. Click the + button next to the Wired entry to create a new profile.
  4. Optional: Set a name for the connection on the Identity tab.
  5. On the IPv4 tab, configure the IPv4 settings. For example, select method Manual, set a static IPv4 address, network mask, default gateway, and DNS server:

    IPv4 settings control center RHEL9
  6. On the IPv6 tab, configure the IPv6 settings. For example, select method Manual, set a static IPv6 address, network mask, default gateway, and DNS server:

    IPv6 settings control center RHEL9
  7. Click the Add button to save the connection. The GNOME control-center automatically activates the connection.

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

    • Ping an IP address in the same subnet.

      For IPv4:

      # ping 192.0.2.3

      For IPv6:

      # ping 2001:db8:1::2

      If the command fails, verify the IP and subnet settings.

    • Ping an IP address in a remote subnet.

      For IPv4:

      # ping 198.162.3.1

      For IPv6:

      # ping 2001:db8:2::1
      • If the command fails, ping the default gateway to verify settings.

        For IPv4:

        # ping 192.0.2.254

        For IPv6:

        # ping 2001:db8:1::fffe
  4. Use the host utility to verify that name resolution works. For example:

    # host client.example.com

    If the command returns any error, such as connection timed out or no servers could be reached, verify your DNS settings.

Troubleshooting steps

  1. If the connection fails or if the network interface switches between an up and down status:

    • Make sure 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 the server is connected to.
    • 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.

Additional Resources

6.12. Configuring an Ethernet connection using nm-connection-editor

Ethernet connections are the most frequently used connection types in physical or virtual servers. This section describes how to configure this connection type using the nm-connection-editor application.

Prerequisites

  • A physical or virtual Ethernet device exists in the server’s configuration.
  • GNOME is installed.

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 General tab:

    1. To automatically enable this connection when the system boots or when you restart the NetworkManager service:

      1. Select Connect automatically with priority.
      2. Optional: Change the priority value next to Connect automatically with priority.

        If multiple connection profiles exist for the same device, NetworkManager enables only one profile. By default, NetworkManager activates the last-used profile that has auto-connect enabled. However, if you set priority values in the profiles, NetworkManager activates the profile with the highest priority.

    2. Clear the All users may connect to this network check box if the profile should be available only to the user that created the connection profile.

    ethernet connection general tab

  5. On the Ethernet tab, select a device and, optionally, further Ethernet-related settings. ethernet connection settings
  6. On the IPv4 Settings tab, configure the IPv4 settings. For example, set a static IPv4 address, network mask, default gateway, and DNS server: IPv4 settings nm connection editor
  7. On the IPv6 Settings tab, configure the IPv6 settings. For example, set a static IPv6 address, network mask, default gateway, and DNS server: IPv6 settings nm connection editor
  8. Save the connection.
  9. Close nm-connection-editor.

Verification steps

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

    • Ping an IP address in the same subnet.

      For IPv4:

      # ping 192.0.2.3

      For IPv6:

      # ping 2001:db8:1::2

      If the command fails, verify the IP and subnet settings.

    • Ping an IP address in a remote subnet.

      For IPv4:

      # ping 198.162.3.1

      For IPv6:

      # ping 2001:db8:2::1
      • If the command fails, ping the default gateway to verify settings.

        For IPv4:

        # ping 192.0.2.254

        For IPv6:

        # ping 2001:db8:1::fff3
    • Use the host utility to verify that name resolution works. For example:

      # host client.example.com

      If the command returns any error, such as connection timed out or no servers could be reached, verify your DNS settings.

Additional Resources

6.13. 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

6.14. 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

6.15. Configuring multiple Ethernet interfaces 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

  • DHCP is available in the network
  • The host has multiple Ethernet adapters
  • 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 steps

  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

6.16. 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

  • DHCP server is available in the network
  • The host has multiple Ethernet adapters
  • No connection profile exists on system

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 steps

  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