[TriLUG] iptables with more than 2 nics

[Ryan Leathers]

Im interested in setting up iptables on a host with several nics.  I
thought this would be a snap but its got me stumped.  Now I must admit
that I have a lot more experience with hardware firewalls (Cisco PIX)
than with IPTABLES, and part of my problem may be that Im trying to see
IPTABLES conform in some way to my tainted expectations.

In short, I want to assign rules on a per interface basis.  I want to
masq between eth0 and eth1 as well as between eth0 and eth2.  I want
eth1 to permit certain traffic and eth2 to permit a different set of
traffic.  Simply plugging in "-i eth1" isn't getting me where I thought
it would.

I have set up a number of IPTABLES instances where one or two nics were
used, but can't find any examples of multi-nic iptables.  Can anyone
point me to good examples?    
 

-- 
Ryan Leathers <ryan.leathers at globalknowledge.com>
Global Knowledge