For a small number of additional addresses:

in /etc/sysconfig/network-scripts/ , copy ifcfg-eth0 (or whichever interface
you want) to, e.g., ifcfg-eth0:0 . Then in ifcfg-eth0:0 , just replace each
instance of "eth0" with "eth0:0", and set the IP address to the one you want
to add.

After saving ifcfg-eth0:0 , do either:

ifup eth0:0


service network restart

or reboot the machine, if you want to be sure it works after reboot.

For a large number of sequential IP addresses:

create /etc/sysconfig/network-scripts/ifcfg-eth0-range0 containing:


IPADDR_START is the address, from which your IP range is starting.

IPADDR_END is the address, by which your IP range is ending.

CLONENUM_START is the number of virtual device the first IP address will be
assigned to. In the above example, applying configuration changes will make IP
address to be mapped to eth0:3 virtual device, to
eth0:4, etc.

you can create several ranges for the same interface, so long as
CLONENUM START values do not overlap.