"This tutorial will walk you through setting up Shorewall (Shoreline) 4.0 firewall on CentOS 5.1; this can easily be adapted to any other Linux distribution out there.
"The Shoreline Firewall, more commonly known as 'Shorewall,' is a high-level tool for configuring Netfilter. You describe your firewall/gateway requirements using entries in a set of configuration files. Shorewall reads those configuration files and with the help of the iptables utility, Shorewall configures Netfilter to match your requirements. Shorewall can be used on a dedicated firewall system, a multi-function gateway/router/server or on a standalone GNU/Linux system. Shorewall does not use Netfilter's ipchains compatibility mode and can thus take advantage of Netfilter's connection state tracking capabilities..."
