How to add your additional IP address (CentOS )These are the steps to add the second IP address to your existing network adapter under CentOS or Redhat distributions of Linux.
1. Become root on your system, either by logging into that account or using the su command. Change your current directory to the /etc/sysconfig/network-scripts directory with the command:
# cd /etc/sysconfig/network-scripts
Check for existing network adapters with the command: ls ifcfg-* In most instances, you will see the files ifcfg-eth0 and ifcfg-lo.
2. 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:
and change the IPADDR line to be the new IP:
3.To activate the new IP address, issue a command similar to:
# ifup eth0:0