I have been at this for such a long time and I still can't figure out. (I'm a newbie.)

I have Slack installed and running. The machine has two NICs, one for cable, and the other to share the cable connection. I can already ping to the internet from the Slackware box and I can also access the Slackware box from within the network, but I can't seem to figure out how I can have Slack route data from one NIC to the other so I can share the internet connection. I've been playing around with route, but I'm not getting anywhere. Any help would be very much appreciated.

I have a very similar setup for one of my networks, and I use Jay's Firewall. It has a simple interface to configure NAT/IP Masquerading.

Thanks a lot! I got it to act as a firewall now ... but I'm having trouble following the instructions on how to get it to run automatically on boot. Any ideas? I don't have any idea what I'm supposed to be doing on /etc/inittab.

I remember running into that at first too.
It looks like the documentation assumes a System V init, whereas Slackware uses a BSD style init. (this is explained in the Slackware book [www.slackware.com/book] if you're interested)

The easy way to get it to run automatically at boot is to add an entry for it in your /etc/rc.d/rc.local. something like this:
hope that helps

It worked great! Thank you very much. You've been of great help.