Configuring an IP address is a fundamental task for network management and connectivity. In a Linux environment, this process is crucial for setting up servers, workstations, and other networked devices. This article will guide you through the steps to configure an IP address on a Linux system using both command-line tools and graphical interfaces. Understanding how to manage IP addresses in Linux can help ensure your network operates smoothly and efficiently.

Examples:

1. Using ifconfig (deprecated but still widely used):

   sudo ifconfig eth0 192.168.1.100 netmask 255.255.255.0 up

This command assigns the IP address 192.168.1.100 with a subnet mask of 255.255.255.0 to the eth0 network interface and brings the interface up.

2. Using ip command (recommended):

   sudo ip addr add 192.168.1.100/24 dev eth0

   sudo ip link set dev eth0 up

Here, 192.168.1.100/24 specifies the IP address and the subnet mask, and eth0 is the network interface.

3. Configuring a static IP address via /etc/network/interfaces (Debian/Ubuntu):

Edit the file /etc/network/interfaces:

   sudo nano /etc/network/interfaces

Add the following lines:

   auto eth0

   iface eth0 inet static

       address 192.168.1.100

       netmask 255.255.255.0

       gateway 192.168.1.1

Save and close the file, then restart the networking service:

   sudo systemctl restart networking

4. Configuring a static IP address via netplan (Ubuntu 18.04 and later):

Edit the netplan configuration file, usually located at /etc/netplan/01-netcfg.yaml:

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

Add the following configuration:

   network:

     version: 2

     ethernets:

       eth0:

         dhcp4: no

         addresses: [192.168.1.100/24]

         gateway4: 192.168.1.1

         nameservers:

           addresses: [8.8.8.8, 8.8.4.4]

Apply the configuration:

   sudo netplan apply

5. Using nmcli (NetworkManager CLI):

   sudo nmcli con add type ethernet ifname eth0 con-name static-eth0 ip4 192.168.1.100/24 gw4 192.168.1.1

   sudo nmcli con up static-eth0

This creates a new connection named static-eth0 with the specified IP address and gateway, and then activates the connection.