Version: Dec 13, 2024

Setting a Static IP Address on Ubuntu Server

1. Identify Network Interface Details

Use the command:
```
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:
```
ls /etc/netplan/
```

3. Back Up the Original Configuration

Always back up the file before making changes:

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:
```
sudo nano /etc/netplan/01-netcfg.yaml
```

Replace or add the following configuration, substituting with your desired IP, gateway, and DNS:

network:
  version: 2
  ethernets:
    eth0:                   # Replace with your interface name
      addresses:
        - 192.168.1.100/24   # Replace with your desired IP and subnet mask
      routes:
        - to: 0.0.0.0/0
          via: 192.168.1.1   # Replace with your gateway
      nameservers:
        addresses:
          - 8.8.8.8          # Google DNS
          - 8.8.4.4

5. Apply Configuration

Apply the changes using:

sudo netplan generate
sudo netplan apply

6. Verify Configuration

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

7. Troubleshooting

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

8. Optional: Disable DHCP (if needed)

If your network was using DHCP and you're switching to a static IP, ensure that DHCP is disabled for the interface.
```
dhcp4: false
```

9. Restart Network Services

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