How to use more IP address for one netcard in Iptables?

[Bobo <boboaq@xxxxxxx>]

Hi

    While  use Iptables as the gateway of my LAN,I would like to use NAT.
 
   I have six   C class address,and I want to use it on one netcard eth0 for NAT.

   Must I bind the six IP address with eth0 step by step under linux ?

  Could I use the six IP address in the Shell scripts while only bind one Ip address 
   with netcard eth0 ?

  Thanks a lot.