Set a static IP for Ubuntu

First of all, we have to know which IP we will assign to our Ubuntu, and the IP of the default gateway. If we have DHCP we can check the current IP that has been assigned to us, the IP of the default gateway and the current DNS servers by running the following commands:

# Get IPv4
ip a s | grep 'inet '

# Get default gateway
ip r | grep 'default'

# Get the current DNS servers
resolvectl status | grep "DNS Server" -A2

For the sake of this example, I will assume that my IP is 192.168.128.100/24 and that my default gateway is 192.168.128.1 and that I want to assign that same IP that I got from DHCP as my static IP. Of course you have to replace these values with the ones you want to set.

Now that we have to edit the file /etc/netplan/00-installer-config.yaml. The name of the yaml can be different depending on your network configuration, the thing is that you have to edit the correct file for your network adapter. When we open we might see something like this:

# This is the network config written by 'subiquity'
network:
  ethernets:
    ens33:
      dhcp4: yes
  version: 2

Again, ens33 might have a different name depending on your Ubuntu installation, and there might even be more than one elements under ethernets. You have to modify the one that you want to set a static IP. Now we have to edit the file to look like the following, using the value that we want for the static IP:

# This is the network config written by 'subiquity'
network:
  ethernets:
    ens33:
      dhcp4: no
      addresses:
        - 192.168.128.100/24
      routes:
        - to: default
          via: 192.168.128.1
      nameservers:
        addresses: [192.168.128.1, 8.8.8.8, 8.8.4.4]
  version: 2

You can set the DNS servers that you want under nameservers: addresses. In this case I used the default gateway and the DNS from Google.

Finally, to apply the changes we run:

netplan apply

The changes should be applied immediately.