Version: Sep 30, 2025

Setting a Static IP Address on Ubuntu Server

1. Identify Network Interface Details

Use the command: bash ip addr
Identify the network interface name (e.g., eth0, ens33, wlan0) and current IP configuration.

2. Access Netplan Configuration

Ubuntu uses Netplan for network configuration. Locate the configuration file, typically in /etc/netplan/. Common filenames are 01-netcfg.yaml or 50-cloud-init.yaml.
Use: bash ls /etc/netplan/

3. Back Up the Original Configuration

Always back up the file before making changes: bash sudo cp /etc/netplan/01-netcfg.yaml /etc/netplan/01-netcfg.yaml.bak

4. Edit the Configuration File

Open the configuration file with a text editor:

bash sudo nano /etc/netplan/01-netcfg.yaml - Replace or add the following configuration, substituting with your desired IP, gateway, and DNS:

```yaml network: version: 2 ethernets: eth0: # Replace with your interface name dhcp4: false addresses: - 192.168.1.100/24 # Replace with your desired IP and subnet mask routes: - to: default via: 192.168.1.1 # Replace with your gateway nameservers: addresses: - 8.8.8.8 # Google DNS - 8.8.4.4

  eth1:
    dhcp4: false
    addresses:
    - 10.10.10.1/24       # second NIC, this example is a private network

```

5. Apply Configuration

Apply the changes using: bash sudo netplan generate sudo netplan apply

6. Verify Configuration

Confirm the changes using: bash ip addr
Test connectivity by pinging the gateway or an external IP: bash ping 8.8.8.8

7. Troubleshooting

If the network does not come up after applying the changes:
Revert to the backup file: bash sudo cp /etc/netplan/01-netcfg.yaml.bak /etc/netplan/01-netcfg.yaml sudo netplan apply
Check Netplan syntax before applying changes: bash sudo netplan try
Verify the correct interface name and ensure no conflicting DHCP settings.

8. Restart Network Services

If issues persist, restart the network service: bash sudo systemctl restart systemd-networkd

9. Optional: Enable forwarding

When you enable IP forwarding, Linux begins routing traffic between interfaces (e.g., from your 192.168.1.0/24 network to your 10.10.10.0/24 network). This is required if Node 1 is acting as a gateway or bridge between your LAN and your direct private network link.
For example, lets say node 1 is your webserver, and node 2 is a NAS, and you decide to private and direct connect node 1 and node 2 together. This private connection is 10.10.10.0 and your other network your workstation is on 192.168.1.0. How to get access 10.10.10.0? We can use node 1 to forward packets instead of an all out gateway, but your workstation needs to know this.

On node 1 bash echo "net.ipv4.ip_forward=1" | sudo tee -a /etc/sysctl.conf sudo sysctl -p

On MacOS workstation - temporary

node 1 ip address example is 192.168.1.50

sudo route -n add 10.10.10.0/24 192.168.1.50

On MacOS workstation - permanent

Create a file

sudo nano /Library/LaunchDaemons/com.local.staticroutes.plist

Add:

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN"
  "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
  <dict>
    <key>Label</key><string>com.local.staticroutes</string>
    <key>ProgramArguments</key>
    <array>
      <string>/sbin/route</string>
      <string>-n</string>
      <string>add</string>
      <string>10.10.10.0/24</string>
      <string>192.168.2.50</string>
    </array>
    <key>RunAtLoad</key><true/>
  </dict>
</plist>

Then load it:

sudo launchctl load /Library/LaunchDaemons/com.local.staticroutes.plist

Now it’ll reapply at every boot.

Test it

You should be able to ping the private network, assuming we made node 1 second NIC 10.10.10.1 and node 2 10.10.10.2

ping 10.10.10.2