Chapter 15. Configuring the loopback interface by using nmcli

Procedure

1. Create a new connection of type loopback:

   # nmcli connection add con-name example-loopback type loopback

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2. Configure custom connection settings, for example:

   1. To assign an additional IP address to the interface, enter:

      # nmcli connection modify example-loopback +ipv4.addresses 192.0.2.1/24

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      Note

      NetworkManager manages the lo interface by always assigning the IP addresses 127.0.0.1 and ::1 that are persistent across the reboots. You cannot override 127.0.0.1 and ::1. However, you can assign additional IP addresses to the interface.

   2. To set a custom Maximum Transmission Unit (MTU), enter:

      # nmcli con mod example-loopback loopback.mtu 16384

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   3. To set an IP address to your DNS server, enter:

      # nmcli connection modify example-loopback ipv4.dns 192.0.2.0

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      If you set a DNS server in the loopback connection profile, this entry is always available in the /etc/resolv.conf file. The DNS server entry remains independent of whether or not the host roams between different networks.

3. Activate the connection:

   # nmcli connection up example-loopback

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Verification

1. Display the settings of the lo interface:

   # ip address show lo
   
   1: lo: <LOOPBACK,UP,LOWER_UP> mtu 16384 qdisc noqueue state UNKNOWN group default qlen 1000
   
   link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00 inet 127.0.0.1/8 scope host lo valid_lft forever preferred_lft forever inet 192.0.2.1/24 brd 192.0.2.255 scope global lo valid_lft forever preferred_lft forever
   
   inet6 ::1/128 scope host
   valid_lft forever preferred_lft forever

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2. Verify the DNS address:

   # cat /etc/resolv.conf
   ...
   nameserver 192.0.2.0
   ...

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