How To Install And Configure Advanced Policy Firewall (APF) On CentOS 5.3

This tutorial explains how you can install and configure APF - an
interface to IPTables which lets you easily configure a full featured
firewall to secure servers and workstations connected to a network.
This guide describes an example installation on a server with cPanel
but it’s only a matter of port numbers which must be open for
everything to work. APF can be used on any system.

Source/Kaynak : http://www.howtoforge.com/how-to-install-and-configure-advanced-policy-firewall-apf-on-centos-5.3