Inspecting the Status of Network Links with `networkctl`

The networkctl command displays information about network connections that helps you configure networking services and troubleshoot networking problems.

You can progressively add options and arguments to the networkctl command to move from general information about network connections to specific information about a network connection.

Running networkctl without options defaults to the list command:

networkctl
IDX LINK             TYPE               OPERATIONAL SETUP
  1 lo               loopback           carrier     unmanaged
  2 eth0             ether              routable    configured
  3 docker0          ether              routable    unmanaged
 11 vethb0aa7a6      ether              degraded    unmanaged
 4 links listed.

Run the networkctl with the status command to display active network links with IP addresses for not only the Ethernet connection, but also the Docker container.

root@photon-rc [ ~ ]# networkctl status
*      State: routable
     Address: 198.51.100.131 on eth0
              172.17.0.1 on docker0
              fe80::20c:29ff:fe55:3ca6 on eth0
              fe80::42:f0ff:fef7:bd81 on docker0
              fe80::4c84:caff:fe76:a23f on vethb0aa7a6
     Gateway: 198.51.100.2 on eth0
         DNS: 198.51.100.2

You can add a network link, such as the Ethernet connection, as the argument of the status command to show specific information about the link:

root@photon-rc [ ~ ]# networkctl status eth0
* 2: eth0
       Link File: /usr/lib/systemd/network/99-default.link
    Network File: /etc/systemd/network/10-dhcp-en.network
            Type: ether
           State: routable (configured)
            Path: pci-0000:02:01.0
          Driver: e1000
      HW Address: 00:0c:29:55:3c:a6 (VMware, Inc.)
             MTU: 1500
         Address: 198.51.100.131
                  fe80::20c:29ff:fe55:3ca6
         Gateway: 198.51.100.2
             DNS: 198.51.100.2
        CLIENTID: ffb6220feb00020000ab116724f520a0a77337

You can add a Docker container as follows:

networkctl status docker0
* 3: docker0
       Link File: /usr/lib/systemd/network/99-default.link
    Network File: n/a
            Type: ether
           State: routable (unmanaged)
          Driver: bridge
      HW Address: 02:42:f0:f7:bd:81
             MTU: 1500
         Address: 172.17.0.1
                  fe80::42:f0ff:fef7:bd81

In the example above, the output indicates that state of the Docker container is unmanaged. Docker uses the bridge drive to handle managing the networking for the containers and not systemd-resolved or systemd-networkd.

For more information about networkctl commands and options, see https://www.freedesktop.org/software/systemd/man/networkctl.html.