[LARTC] Snooping

[Jim Redman <jredman@xxxxxxxxxxxx>]

I'm try to insert a snooping/modifying application in a network without 
changing the network.  That is, I want to take a linux box with two 
ethernet ports and put it between two existing systems without changing 
the original IPs.  So, I want to change (for example) this:

host(192.168.253.1)
         |
         |
target(192.168.253.2)

to:

host(192.168.253.1)
         |
         |
     snooper
         |
         |
target(192.168.253.2)

The snooper needs an interface to listen on (socket) that looks to the 
host like 192.168.253.2 and it needs to talk to the real target on 
192.168.253.2.  It's not a bridge, packets do not go from the host to 
the target, the snooper is 
It seems that it should be possible to do this with some combination of 
proxyARP, iptables and routing, any suggestions appreciated.

Jim

--

Jim Redman
(505) 662 5156 x85
http://www.ergotech.com