IP address is a unique identifier assigned to every device connected to a network. IP addresses in Linux, is used to identify the system on the network and communicate with other devices. There are two main types of IP addresses: IPv4 and IPv6.

IP Address in Linux

In Linux, IP addresses can be assigned to a network interface either statically or dynamically using the Dynamic Host Configuration Protocol (DHCP). A static IP address is manually assigned to the network interface, while a dynamic IP address is assigned by a DHCP server.

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Why You Need Multiple IP Addresses

Multiple IP addresses are needed when a single system needs to communicate with multiple networks, or when multiple services need to run on a single system and each service requires a unique IP address. For example, a web server running multiple websites might require multiple IP addresses, each assigned to a different domain name.

Benefits of Multiple IP Addresses in Linux

There are several benefits to using multiple IP addresses in Linux, including:

1. Better network security: Each IP address can be assigned to a different network interface, allowing you to segment your network and increase security.
2. Improved service availability: With multiple IP addresses, you can assign each address to a different service, improving the availability of those services.
3. Increased network capacity: Multiple IP addresses allow you to host multiple services on a single system, increasing the capacity of your network.
4. Improved load balancing: By assigning multiple IP addresses to different network interfaces, you can balance the load between multiple services, improving performance and reliability.

How to Set Up Multiple IP Addresses in Linux

Setting up multiple temporary IP addresses in Linux is a simple process that can be accomplished using the ifconfig or ip command.

#ip addr add [IP ADDRESS/Subnet Mask] dev [interface]

The following command adds the IP address 192.168.1.2 to the interface enp0s3.

 #ip addr add 192.168.2.1 dev snp0s3

Here is an example using the ip command:

Note that in the above examples, enp0s3 is the network interface and 192.168.1.5 is the IP address being added. Replace these values with the appropriate values for your system.

Multiple IP addresses permanently

If you connect your computer with some different IP subnets regularly, you can configure multiple IP addresses permanently. Linux stores IP configuration and other network settings of an interface in a configuration file. For the naming convention, it uses the interface name with the ifcfg prefix. For example, if the interface name is enp0s3, then the file name will be ifcfg-enp0s3. Linux stores all configuration files in the /etc/sysconfig/network-scripts/ directory.

You can use any text editor to update this file. After updating this file, you need to restart the interface.

Use the following commands to restart the interface and its connections.

#nmcli connection down [interface]
#nmcli connection up [interface]
#nmcli connection reload

With the help of nmtui Tool

If you don’t want to edit configuration files directly, you can use the nmtui utility. The Linux ip address Command Usages and Examples utility allows you to add, remove, update, and manage multiple IP addresses.

Use the following steps to configure and manage multiple IP addresses.

• Use the nmtui command to start the utility
• Select the ‘Edit a connection’ option and press the Enter key
• Select the interface from the left pane and the ‘Edit’ option from the right pane and press the Enter key
• On the IPv4 configuration option, select the Manual method, select the Add option and press the Enter key
• Set the new IP address
• To remove an IP address, use the Remove option
• You can also update/change an existing IP address
• After making changes, select OK and press the Enter key
• On the previous screen, select the Back option and press the Enter key
• On the main screen, use the Quit option to quit the utility

In conclusion, having multiple IP addresses in Linux can greatly improve the security, availability, and performance of your network. By following the steps outlined above, you can easily set up multiple static IP addresses on your Linux system.