Command Center

If you are a Network Administrator some time you need to assign more than ONE ip address (second ipaddress) to your network card of Ubuntu machine. For this you need to edit the /etc/network/interfaces file by adding the following lines . See the example below and make change according to your ip address settings
#vi /etc/network/interfaces
auto eth0
iface eth0 inet static
address 192.168.0.5
netmask 255.255.255.0
network x.x.x.x
broadcast x.x.x.x
gateway x.x.x.x
auto eth0:1
iface eth0:1 inet static
address 192.168.0.50
netmask 255.255.255.0
network x.x.x.x
broadcast x.x.x.x
gateway x.x.x.x
after entering the values save this file and you need to restart networking services in ubuntu using the following command to take effect of our new ipaddress.
After entering all the details you need to restart networking services using the following command
#/etc/init.d/networking restart

REFERENCES
http://shibuvarkala.blogspot.com/2008/10/howto-setup-second-ip-address-or.html

http://www.debian-administration.org/articles/68
 http://www.debianhelp.co.uk/network.htm
http://library.linode.com/networking/configuring-static-ip-interfaces/