[ale] Bridging + Firewall

[Christopher Fowler]

I want to put a machine between my firewall and my desktop.  This
machine will have a network interface and a USB network interface.  I
want to bridge those interfaces as br0 and do a firewall on it.  This is
for a proof of concept.  I'm used to using iptables and specifing the
individual interfaces but how would I do that for eth0 and eth1 if in
reality they become simply one interface as br0?