Setting up firewall on 2 interface within same subnet?

["Jason Chan <MIS Dept.>" <jsonchan@ebhk.com.hk>]

Hi all,

I have a few things to clarify on configuring firewall on the same subnet. 

I have 2 interface on this Linux-Box. Which I am trying to configure the
same interface 
on the same subnet. Is it possible? Do i need to segment them on 2 diff
subnet? pls 
explain if there is no possibilities to install a firewall with 2 interfaces
on the 
same subnet(shown below).
                         
                    [gateway:201.10.10.1]
                   /
                 /
----------------------------------------------
                 |
                 |[interface 1: 201.10.10.10]
          ---------
         <LINUX-BOX>
          ---------
                 |[interface 2: 201.10.10.11]
-----------------------------------------------
                 |
         [client] {201.10.10.12-13}
                  {gateway:201.10.10.1}


regards