Setting a manual static IP on Ubuntu Server ensures predictable networking, which is critical for servers, firewalls, DNS systems, and virtualization hosts.

This guide configures a permanent static IPv4 address using Netplan and disables cloud-init network management to prevent changes on reboot.

• Example Values Used
• 1 Identify Your Network Interface
• 2 Locate Your Netplan File
• 3 Backup the Existing Netplan File
• 4 Edit Netplan and Set the Static IP
• 5 Prevent cloud-init From Overwriting Networking
• 6 Apply the Configuration Safely
• 7 Verify the New Network Settings
• Troubleshooting
  • IP Conflict
  • Recover Quickly
• Final Thoughts

Example Values Used

• Interface: ens18
• Static IP: 192.168.9.112
• Netmask: 255.255.255.0 (CIDR: /24)
• Gateway: 192.168.9.1

• DNS servers:

  • 192.168.9.111
  • 192.168.9.113
  • 8.8.8.8

Adjust these values for your environment.

1 Identify Your Network Interface

Run:

ip -br link
ip -br addr

Locate the interface that currently has your IPv4 address. In this example, it is ens18.

2 Locate Your Netplan File

Run:

ls -lah /etc/netplan/

On many template or cloud-based installs, you will see a file named:

• 50-cloud-init.yaml

3 Backup the Existing Netplan File

Before modifying anything, create a backup:

sudo cp -a /etc/netplan/50-cloud-init.yaml /etc/netplan/50-cloud-init.yaml.bk

4 Edit Netplan and Set the Static IP

Open the file:

sudo nano /etc/netplan/50-cloud-init.yaml

Replace the contents with the following (update ens18 if needed):

network:
version: 2
renderer: networkd
ethernets:
ens18:
dhcp4: no
addresses:
- 192.168.9.112/24
routes:
- to: default
via: 192.168.9.1
nameservers:
addresses:
- 192.168.9.111
- 192.168.9.113
- 8.8.8.8

Notes:

• 192.168.9.112/24 corresponds to netmask 255.255.255.0.
• If you want to disable DHCPv6 as well, add: dhcp6: no under dhcp4: no.

5 Prevent cloud-init From Overwriting Networking

If your file is named 50-cloud-init.yaml, cloud-init may regenerate it on reboot unless networking is disabled.

Run:

sudo mkdir -p /etc/cloud/cloud.cfg.d
echo 'network: {config: disabled}' | sudo tee /etc/cloud/cloud.cfg.d/99-disable-network-config.cfg

This prevents cloud-init from managing network configuration.

6 Apply the Configuration Safely

If connected via SSH, use:

sudo netplan try

• If connectivity remains stable, press Enter to confirm.
• If connectivity breaks, the configuration automatically rolls back.

If you are on local console access, you may instead use:

sudo netplan apply

7 Verify the New Network Settings

Run:

ip -br addr show ens18
ip route
resolvectl status | sed -n '1,120p'

You should see:

• ens18 with 192.168.9.112/24
• Default route via 192.168.9.1
• DNS servers set correctly

Troubleshooting

IP Conflict

Ensure 192.168.9.112 is not already in use and not inside an active DHCP pool unless properly reserved.

Recover Quickly

If networking breaks and you have console access, restore the backup:

sudo cp -a /etc/netplan/50-cloud-init.yaml.bk /etc/netplan/50-cloud-init.yaml
sudo netplan apply

Final Thoughts

Using Netplan with cloud-init properly disabled ensures your Ubuntu Server retains its static IP configuration permanently. This approach is reliable, audit-friendly, and appropriate for production environments where predictable networking is required.