Building a NAT router?

[Jason Montleon]

You could also use a program like firestarter to configure it.

The wizard will ask you some questions about which interface is internet
facing, whether it is statically/dynamically assigned, do you want to block
certain types of ICMP traffic, allow any services to be accessed from the
outside, do you want to enable NAT and so on.  When you're done it runs and
you have firewall and NAT.

If you are interested you can check it out here:
firestarter.sourceforge.net.  They have an RPM for RedHat 8 and 9 that also
works with Severn.

All it does is act as an easy to use graphical interface for configuring
iptables.  The firewall.sh can be edited after the fact.  I for example had
to create rules allowing traffic from any source port from one specific
address to destination port 49149 (this was to get Nortel Networks Contivity
VPN working such that I could use more than one IPSec tunnel through a NAT
device, and was a little out of the scope of what Firestarter was created to
handle.)

And if you don't like firestarter there is probably a list of similar
programs as long as your arm.  Such is the wonderful way of open source :)

Regards,
Jason