Set a static IP address: nmcli on RHEL vs netplan on Ubuntu

Servers usually need a fixed address. How you set it depends on the distribution: RHEL and its rebuilds manage interfaces with NetworkManager, controlled by nmcli. Ubuntu Server uses netplan: you describe the network in a YAML file and netplan hands it to a backend (systemd-networkd on servers, NetworkManager on desktops). Debian without netplan often still uses /etc/network/interfaces, which is not covered here.

The examples use interface enp1s0, address 192.0.2.10/24, gateway 192.0.2.1 and DNS server 192.0.2.53. Replace them with your values.

Warning: changing the address of the interface you are connected through will cut your SSH session if anything is wrong. Use the server console (hypervisor, IPMI, cloud serial console) when possible, or netplan’s try mode described below.

Step 0: find the interface name

ip -br address
ip route show default

RHEL, Rocky, AlmaLinux: nmcli

NetworkManager stores settings in connection profiles. First find the profile that belongs to the interface:

nmcli device status
nmcli connection show

Then switch that profile from DHCP to a static address (the profile is often named like the interface, but not always):

sudo nmcli connection modify enp1s0 \
  ipv4.method manual \
  ipv4.addresses 192.0.2.10/24 \
  ipv4.gateway 192.0.2.1 \
  ipv4.dns 192.0.2.53 \
  ipv4.dns-search example.com
sudo nmcli connection up enp1s0

modify only changes the saved profile; connection up applies it. The profile is stored on disk and survives reboots. To go back to DHCP: sudo nmcli connection modify enp1s0 ipv4.method auto ipv4.addresses '' ipv4.gateway '', then connection up again.

If you prefer a menu, nmtui offers the same settings in the terminal.

Ubuntu Server: netplan

Netplan reads YAML files from /etc/netplan/ (also /run/netplan/ and /lib/netplan/) in alphabetical order; later files override earlier ones. The installer or cloud-init usually creates one already. Look at what is there, back it up, and edit that file rather than adding a conflicting one:

ls /etc/netplan/
sudo cp /etc/netplan/50-cloud-init.yaml /root/netplan-backup.yaml   # use your file name
sudo nano /etc/netplan/50-cloud-init.yaml

network:
  version: 2
  renderer: networkd
  ethernets:
    enp1s0:
      dhcp4: false
      addresses:
        - 192.0.2.10/24
      routes:
        - to: default
          via: 192.0.2.1
      nameservers:
        addresses: [192.0.2.53]
        search: [example.com]

YAML is indentation-sensitive: use spaces, never tabs. Older guides use a gateway4: key; current netplan uses a routes: entry with to: default instead.

If a file was written by cloud-init, cloud-init may regenerate it on the next boot. Its header comment explains how to disable that; follow it, or your change may be overwritten.

Apply safely with netplan try. It applies the new config and rolls it back automatically after 120 seconds unless you confirm, so a mistake does not lock you out:

sudo netplan generate     # syntax check, writes backend config only
sudo netplan try          # apply, press Enter to keep it
sudo netplan apply        # apply without the safety net

Verify (both distributions)

ip address show enp1s0
ip route show default
resolvectl status enp1s0     # on systems using systemd-resolved
cat /etc/resolv.conf
ping -c 3 192.0.2.1

Then reboot once during a maintenance window to be sure the address comes back on its own.

Do not mix tools

Pick the tool your distribution uses and stick with it. Commands like ip address add change the running state only and are lost at reboot; editing files that NetworkManager or netplan generate is overwritten the next time those tools run.

Official documentation

• RHEL 9: Configuring an Ethernet connection
• Netplan configuration examples
• netplan try