How To Assign IP Address To Remote Linux Systems Via SSH

This guide demonstrates how to assign an IP address to a remote Linux system using the nmcli command. This is useful for various reasons, including network policy compliance, troubleshooting, network migration, and enhanced security.

Several scenarios necessitate remote IP address changes:

• Network Policy Adherence: Many organizations mandate specific IP address ranges.
• Network Troubleshooting: Altering the IP address can sometimes resolve network issues.
• Network Migration: Moving a system to a new network requires an IP address change.
• Security Enhancement: A new IP address makes the system harder for attackers to identify.

Using nmcli via SSH provides a convenient solution.

Assigning an IP Address with nmcli

First, identify the remote system's network interface using:

ssh user@remote_ip 'nmcli con show'

Replace user and remote_ip with the appropriate credentials. The output will show the network interface name (e.g., Wired connection 1).

Next, modify the IP address using:

ssh -t user@remote_ip "sudo nmcli con modify 'Interface Name' ipv4.address new_ip/subnet_mask"

Replace Interface Name, new_ip, and subnet_mask with the correct values (e.g., "Wired connection 1", 192.168.1.50/24). The -t flag ensures proper password prompting. You'll be prompted for the remote user's password, and then for sudo on the remote machine.

Verify the change with:

ssh user@remote_ip "ip addr show interface_name"

Replace interface_name with the interface's name (e.g., ens18).

Alternative (Insecure) Method:

While less secure, you can use echo and piping to avoid repeated password entry:

echo 'password' | ssh -t user@remote_ip "sudo -S nmcli con modify 'Interface Name' ipv4.address new_ip/subnet_mask"

Caution: This method exposes your password and is strongly discouraged. Using SSH keys is the recommended secure approach.

Automated Script:

A Bash script, nmcli_remote_ip_changer.sh, simplifies this process. It prompts for remote credentials, identifies interfaces, and applies the new IP configuration, including gateway and DNS settings. The script can be found at [GitHub Link - Replace with actual GitHub link if available]. Remember to make it executable (chmod x nmcli_remote_ip_changer.sh) before running.

Conclusion:

nmcli offers a streamlined method for managing remote Linux system IP addresses. While direct command execution is efficient, using a script like nmcli_remote_ip_changer.sh enhances usability and security when coupled with SSH key-based authentication. Prioritize secure practices to protect your systems.

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