How do I assign additional IP addresses in RedHat/CentOS?

If you are using CPanel, you should add the IP addresses through WHM.  Do not follow these instructions if you are using CPanel.

If you want to assign the addresses 3.2.1.1 – 3.2.1.20 to your server, you will need to create a RANGE file.

cd /etc/sysconfig/network-scripts
ls ifcfg-eth1-range*

If you already have a range file, you will need to create a new one for the new range of IPs you are adding, eg ‘nano ifcfg-eth1-range1` .  If you have one named range1, name the next range2 and so on.

nano ifcfg-eth1-range1

Place the following text in the file:

IPADDR_START=192.168.0.10
IPADDR_END=192.168.0.110
CLONENUM_START=0

Note: CLONENUM_START defines where the alias will start.  If this is the second range file, you will need to set CLONENUM_START to a value higher than the number of IP addresses assigned.  To check what you currently have used, you can run ‘ifconfig –a | grep eth1’.  This will list devices such as eth1:0, eth1:1, eth1:2, and so on.  If you are currently using upto eth1:16, you will need to set CLONENUM_START to 17 to assign the IPs correctly.