IP addresses are fundamental to networking, serving as unique identifiers for devices on a network. In a Linux environment, managing and configuring IP addresses is crucial for network communication, troubleshooting, and administration. This article will guide you through the processes of viewing, configuring, and managing IP addresses using various Linux commands and tools.

Examples:

1. Viewing IP Addresses

To view the current IP addresses assigned to your network interfaces, you can use the ip command:

   ip addr show

This command will display detailed information about all network interfaces and their associated IP addresses.

Alternatively, you can use the ifconfig command, which is part of the net-tools package:

   ifconfig

2. Assigning a Static IP Address

To assign a static IP address to a network interface, you can use the ip command. For example, to assign the IP address 192.168.1.100 with a subnet mask of 255.255.255.0 to the eth0 interface, you would run:

   sudo ip addr add 192.168.1.100/24 dev eth0

To make this configuration persistent across reboots, you need to edit the network configuration file, typically found at /etc/network/interfaces or /etc/sysconfig/network-scripts/ifcfg-eth0 depending on your Linux distribution.

For Debian-based systems (e.g., Ubuntu):

   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

For Red Hat-based systems (e.g., CentOS, Fedora):

   sudo nano /etc/sysconfig/network-scripts/ifcfg-eth0

Add or modify the following lines:

   DEVICE=eth0

   BOOTPROTO=static

   IPADDR=192.168.1.100

   NETMASK=255.255.255.0

   GATEWAY=192.168.1.1

   ONBOOT=yes

3. Releasing and Renewing a DHCP Lease

If your network interface is configured to use DHCP, you might need to release and renew the IP address. This can be done using the dhclient command:

To release the current DHCP lease:

   sudo dhclient -r eth0

To renew the DHCP lease:

   sudo dhclient eth0

4. Checking Network Connectivity

To verify that your IP address configuration is correct and that you have network connectivity, you can use the ping command:

   ping -c 4 8.8.8.8

This command will send 4 ICMP echo requests to Google's public DNS server and display the results.