[Bridge] transparent bridge and proxies

[Julian Lyndon-Smith <asterisk@dotr.com>]

I want to be able to install a box that is a transparent bridge, but 
that is also running a transparent proxy, but with a twist ..

i am a newbie in all things linux, so bear with me :)

So far I have managed to install centos 4.3, and following various 
guides on the net, created a bridge between eth1 (connected to lan) and 
eth0 (connected to router). That works great.

I also managed to install squid, get it running transparently and added 
a rule to iptables to make all that work just fine. So now, all my 
clients attached to the lan run through the squid proxy without them 
knowing.

Now, for the twist. For development and testing, I assigned an ip 
address and gateway to the bridge. I need to be able for a "non-it" 
person to install this box without having to set it up at all , so it 
cannot have an ip address assigned, as it *may* be in use somewhere else 
on the lan or router.

So, I changed the ip address to 0.0.0.0. Everything except squid still 
worked. I presume that's because it does not know how to route the data 
to get stuff.

Can I add a rule to iptables or something to say "anything that's come 
from eth1 into the local box, after processing send to eth0" and 
vice-versa ?

Julian.