Linux Firewall Software

A firewall on Linux does not need to be installed so much as it needs to be activated. Linux has a feature called IP Masquerading built in that can allow the operating system to act as a NAT firewall and router for your entire network. NAT allows all the computers on your LAN to access the internet through a single Internet registered IP address on your Linux computer.
Linux supports packet filtering. A packter filtering personal firewall can check the packet type, source address, destination address, and port information to ensure all data packets follow a rule set. This is a very powerful type of firewall that is very transparent to the users on your LAN.. Here are a list of resources to help you configure your Linux computer as a firewall.
Linux Firewall and Security Site
Firewall and Proxy Server HOWTO
Linux IP Masquerading Web Site
Linux IP Masquerade HOWTO
Internet Firewalls: Frequently Asked Questions
Micro Distributions
There is also a movement on the Internet that is creating ‘micro’ distributions of Linux with all the firewall protection capabilities built in. These micro-distributions can be run from a single 1.4Mb floppy disk and do not require a hard drive! A simple 486 with two NIC’s and a floppy drive is usually all that is required. Some of these firewalls can even be created and setup under Windows so no Linux knowledge is necessary & can place all of your computers behind a firewall
Smoothwall GPL - configure through browser!
Linux Router Project
Cyote Linux
For NetBSD Fans, The NetBSD/i386 Firewall Projects
 
 

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