Firestarter is a firewall tool for Linux, and uses GNOME. You can use the wizard to create a basic firewall, then streamline it further using the dynamic rules. You can open and close ports with a few clicks, or stealth your services giving access only to a select few. It features a real-time hit monitor which you can watch as attackers probe your machine for open ports.
The goal of FireStarter is to provide easy to use, yet powerful, graphical tools for setting up, administrating and monitoring firewalls for Linux machines.
Firestarter is a free and open source personal firewall tool that uses the Netfilter (iptables/ipchains) system built into the Linux kernel. Firestarter provides a graphical interface for configuring firewall rules and settings. It also provides real-time monitoring of all network traffic for the system.