I found a link to configure the firewall on RH 9 at http://linuxwww.epfl.ch/Doc/rh-9/rhl...llconfig.html.
As far as the cable modem goes, it may or may not be supported under Red Hat. Just because it's USB doesn't garantee it will work with Red Hat Linux (or any other Linux for that matter.) You need to check out Red Hat's Hardware Compatibility List (HCL as they call it) and see whether your make and model is supported. If it is, you'll have to do a little configuring to get it up and running. If it isn't, you may want to get an Ethernet-based cable modem and drop in a router. Linksys, D-Link, and SMC all make great cable modems and routers that are inexpensive and easy to set up. This will allow Internet sharing and still allow file/printer sharing (provided you have Samba up and running) between the two computers.

-Shad