Add a static route with netplan in Ubuntu 18.04, 20.04, 22.04 and 24.04

In this post we see how to add a static route in Ubuntu using ip route and netplan.

The ip route command is useful for adding a temporary route. To keep the route configured persistently in Ubuntu 18.04, 20.04, 22.04 and 24.04, we will use netplan.

Temporary route with ip route

To add a temporary route to a specific network through an interface:

sudo ip route add 192.168.12.0/24 dev ens18

With this command we indicate that traffic to the 192.168.12.0/24 network must leave through the ens18 interface.

If the remote network is behind a specific gateway:

sudo ip route add 192.168.12.0/24 via 192.168.1.1

We can also specify both gateway and interface:

sudo ip route add 192.168.12.0/24 via 192.168.1.1 dev ens18

To review the routing table:

ip route show

To check which route the system would use to reach a specific IP address:

ip route get 192.168.12.10

Persistent route with netplan

Netplan stores network configuration in YAML files inside /etc/netplan/. First, check which file exists:

ls -l /etc/netplan/

Example with DHCP on the ens18 interface and a static route to 192.168.12.0/24 using the 192.168.1.1 gateway:

network:
  version: 2
  renderer: networkd
  ethernets:
    ens18:
      dhcp4: true
      routes:
        - to: 192.168.12.0/24
          via: 192.168.1.1

If we need to define a metric:

network:
  version: 2
  renderer: networkd
  ethernets:
    ens18:
      dhcp4: true
      routes:
        - to: 192.168.12.0/24
          via: 192.168.1.1
          metric: 100

Then validate the configuration:

sudo netplan generate

If there are no errors, test the change with automatic rollback:

sudo netplan try

If everything works, apply it permanently:

sudo netplan apply

Change the default route

To change the default route with netplan, use to: default:

network:
  version: 2
  renderer: networkd
  ethernets:
    ens18:
      addresses:
        - 192.168.1.20/24
      routes:
        - to: default
          via: 192.168.1.1
      nameservers:
        addresses:
          - 1.1.1.1
          - 8.8.8.8

On remote servers, it is best to always use netplan try before netplan apply. An incorrect gateway can leave the machine without SSH access.

Quick summary

• ip route add: adds temporary routes, useful for testing.
• netplan: common persistent configuration in Ubuntu 18.04, 20.04, 22.04 and 24.04.
• netplan generate: validates/generates the configuration.
• netplan try: tests the change with rollback.
• netplan apply: applies the change permanently.