To add another IP address to interface eth0, create a file /etc/sysconfig/network-scripts/ifcfg-eth0:1
and add the following:
and add the following:
DEVICE=eth0:1
ONBOOT=yes
BOOTPROTO=none
IPADDR=your.new.ip.address
NETMASK=enter.the.subnet.mask
Save the file and then, restart networking, i.e.
/etc/init.d/network restart