Hi agent003, welcome to LQ.org!
If you are running iptables, then you can checkout
Jay's Firewall. It's a console-based GUI for setting up a firewall. It requires ncurses and Perl.
And as always, unSpawn gives some excellent advice: RH 7.3 is pretty darned old, and a lot of exploits/vulnerabilities have been found that you need to be aware of.
Enjoy!
--- Cerbere