How to add a second IP address in Linux

These are the steps to add the second IP address in Linux.

1. Become root on your system, either by logging into that account or using the su command.
2. Change your current directory to the /etc/sysconfig/network-scripts directory with the command:
   

   cd /etc/sysconfig/network-scripts

3. Check for existing network adapters with the command:
   

   ls ifcfg-*

   In most instances, you will see the files ifcfg-eth0 and ifcfg-lo.

4. Edit /etc/hosts and add a line for your new address and name such as:
   

   10.0.0.10 new.domain.com

5. To create the new interface, you will copy ifcfg-eth0 to ifcfg-eth0:0 with the command:
   

   cp ifcfg-eth0 ifcfg-eth0:0

   Next, edit icfg-eth0:0 and change the DEVICE line to be similar to:

   DEVICE=eth0:0

   and change the IPADDR line to be similiar to:

   IPADDR=10.0.0.10

6. To activate the new IP address, issue a command similar to:
   

   ./ifup eth0:0

Thank you goes to Useful Utilities.

Reference:
Userful Utilities