When managing a Linux-based system, network configuration is one of the key tasks for ensuring smooth communication and network management. NetworkManager, a popular tool used for managing network connections in Linux, offers a command-line interface (CLI) called NMCLI. It provides a powerful and flexible way to manage network settings, including the configuration of additional IP addresses. This is particularly useful when you need to assign multiple IP addresses to a single network interface for various purposes, such as hosting multiple services or balancing network traffic. This guide will walk you through the steps to configure Additional IPs NMCLI.

Step-by-Step Guide to Configuring Additional IPs Using NMCLI

1. View Existing Network Configuration

Before configuring additional IPs, it's important to review the current network settings. Open a terminal and run the following command to view the details of your active network connections:

 

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nmcli connection show

This will list all the active connections. Identify the connection you want to modify, usually named something like Wired connection 1 or eth0, depending on your system setup.

2. Add an Additional IP Address

Now that you know the name of the network connection, you can add an additional IP address to the interface. Use the nmcli command as shown below:

 

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nmcli connection modify <connection-name> +ipv4.addresses <new-ip-address>/24

Replace <connection-name> with the name of your network connection and <new-ip-address> with the additional IP address you want to assign. For example, if you want to add 192.168.1.101 as an additional IP address to eth0, the command would look like this:

 

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nmcli connection modify eth0 +ipv4.addresses 192.168.1.101/24

3. Configure the Routing Table (If Necessary)

If you're configuring additional IP addresses for routing purposes or to manage traffic between different subnets, you may also need to modify the routing table. This can be done by adding routes for specific IP addresses. Use the following command to add a static route:

 

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nmcli connection modify <connection-name> +ipv4.routes "<destination-network> <gateway>"

For example, to add a route for the 192.168.2.0/24 network through a specific gateway, the command would look like this:

 

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nmcli connection modify eth0 +ipv4.routes "192.168.2.0/24 192.168.1.1"

4. Activate the New Configuration

Once you’ve made the changes, you need to activate the new configuration. To apply the changes without restarting the system, run the following command:

 

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nmcli connection up <connection-name>

This will apply the changes and bring the connection back up with the new IP configuration.

5. Verify the Changes

After applying the new configuration, it’s important to verify that the additional IP address has been successfully assigned. You can do this by checking the network interface’s IP configuration with the following command:

 

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ip addr show <interface-name>

For example, if you’re working with eth0, you would run:

 

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ip addr show eth0

This will list all IP addresses associated with the interface, including the newly added ones.

Why Use NMCLI for Configuring Additional IPs?

Using NMCLI to configure additional IP addresses offers several benefits:

• Simplicity: It provides a straightforward command-line interface for network configuration.

• Automation: NMCLI commands can be scripted for automation, making it easy to apply configurations across multiple systems.

• Flexibility: You can configure IP addresses, routing, DNS, and more from the command line, making it ideal for servers or headless systems.

• Network Control: NMCLI integrates well with NetworkManager, giving you granular control over network settings and interfaces.

Conclusion

Configuring additional IP addresses using NMCLI is a straightforward process that allows system administrators to manage network configurations efficiently. Whether you're setting up multiple services or managing complex network setups, NMCLI provides a robust toolset for adding, removing, and modifying IP addresses without the need for a graphical interface. By following the steps outlined above, you can quickly and easily configure additional IPs on your system, streamlining your network management tasks.