NEWBIE: ipchains/route problem

["Nick Porter" <nickp@flyingpig.com>]

I think this is probably not the correct list to send this to but I can't
find one specifically for routing and it is sort of a firewall question.

I'm currently trying to learn how to configure a firewall/router and have
become confused about the way the routing table and the forwarding table
coexists.

This is what I have;

          Internet connection
                  |
                  |
            -------------
            |  router/   |
            | firewall   |
 WAN Link---|            |-------Private net
            -------------

IC 	= 192.168.0.1 eth0
WAN	= 192.168.1.1 eth1
PN	= 192.168.2.1 eth2

Now, if I wanted to route all traffic intended for the WAN link from the
private net do I need to add a route to that link in the routing table...

route add -net 192.168.1.0 dev eth1

...or do I just add statements to the ipchains forwarding table...

ipchains -A forward -i eth1 -d $WAN -j MASQ

...or do I need both?

What is the relationship between these two tables?

TIA
--
NP