gShield is an aggressive, modular, ipchains-based firewall script. Features include: easy configuration through a BSD-style configuration file, optional IPmasq support, TCP-wrapper-like funtionality for service access, and extremely restrictive defaults. It hopes to make administrating a comprehensive firewall easier, as well as offering robust protection while being easy to setup/maintain.
You can download it from the following link: https://packetstormsecurity.com/files/download/10421/gShield-1.5.1.tar.gz
Source: https://packetstormsecurity.com/files/10421/gShield-1.5.1.tar.gz.html