The Firewall FAQ
Dartmouth College Institute for Security Technology Studies firewall FAQ and other information and research documents in related areas.
http://www.ists.dartmouth.edu/IRIA/knowledge_base/firewall_faq.htm

Firewalls and Internet Security: Repelling the Wily Hacker
Web site for the book Firewalls and Internet Security: Repelling the Wily Hacker Second Edition by William R. Cheswick, Steven M. Bellovin, and Aviel D. Rubin. Contains some sample sections and a link to the complete contents of the First Edition.
http://www.wilyhacker.com/

How Stuff Works: Internet Firewalls
An introductory explanation of how a firewall works and the various filtering methods used, with related links.
http://www.howstuffworks.com/firewall.htm

Interhack.net: Firewalls Frequently Asked Questions
Features a background, basics, design, implementation issues, port and protocol issues. By Matt Curtin and Marcus Ranum. Documents are also available in Postscript and PDF.
http://www.interhack.net/pubs/fwfaq/

Internet Protection and Security by Firewalls Paper
General overview of firewalls and their roles in mitigating various forms of network attacks. Includes case studies.
http://www.geocities.com/francis_abraham/tech_docs/firewall.html

Linux Firewall and Proxy Server HOWTO
White paper outlining the basics of firewall systems and giving details on setting up both, a filtering and proxy firewall on a Linux based system.
http://www.grennan.com/Firewall-HOWTO.html

Network Security, Filters and Firewalls
This article is a general introduction to network security issues and solutions in the Internet; emphasis is placed on route filters and firewalls. It is intended as an overview. Some knowledge of IP networking is assumed, although not crucial.
http://www.acm.org/crossroads/xrds2-1/security.html

Routing/Firewalls with Linux
A brief straightforward tutorial on creating a simple routing firewall using Linux and netfilter (iptables).
http://hnsg.net/tutorials/routing_firewall.html

Samba Authenticated Gateway
This documents intends to show how to build a Firewall/Gateway with rules set on user basis having the users authenticated by a Samba Primary Domain Controller
http://www.tldp.org/HOWTO/Samba-Authenticated-Gateway-HOWTO.html

SecurityDocs Firewall Reference
A collection of whitepapers and other documents on various aspects of firewalls such as what they are, how to choose one, and proper installation.
http://www.securitydocs.com/Firewall

Solaris 2.6 Firewall Example Installation and Configuration
Details the procedure to configure a secure firewall on the Sun Solaris platform.
http://www.roble.com/docs/secure_solaris.html

Vicomsoft Firewall Q&A
A whitepaper on relevant firewall questions and answers. The knowledge of this subject relates to firewalls in general use, and stems from NAT and proxy firewall technology experience. Welcomes feedback and comments from any readers on the usefulness or content.
http://www.vicomsoft.com/knowledge/reference/firewalls1.html

KnowPlace Firewalling
An overview of firewalls and security with particular reference to firewalling with Linux 2.4 and Netfilter/Iptables.
http://www.knowplace.org/netfilter/

Packet filter (pf) mailing list
Mailing list for the pf firewall provided as part of the OpenBSD kernel.
http://www.benzedrine.cx/mailinglist.html

Home PC Firewall Guide
Features information on security, personal firewall software and Internet security appliances for dial-up and broadband-connected (xDSL and cable modem) home and SOHO computers. Also offers reviews of anti-virus and anti-Trojan products and software.
http://www.firewallguide.com/

Outpost Firewall - The Webhiker's Guide
Includes guide to Outpost Firewall, with information for both inexperienced and expert users.
http://www.outpostfirewall.com/guide/

Personal Firewalls - what they can do and what they can't
One author's detailed, non-technical article explaining personal firewalls, their abilities, uses, and li
http://www.geocities.com/uzipaz/eng/pfnt.html

"Personal Firewalls" are Mostly Snake-oil
The author explains his opinion that a personal firewall "provides no real additional security over turning off the services that you don't use".
http://www.samspade.org/d/firewalls.html

Shields Up: Personal Firewalls
Features FAQs, reviews, ratings, white papers, and tools to test Internet security and firewall vulnerabilities by Steve Gibson.
http://grc.com/su-firewalls.htm

CPUG: The Check Point User Group
A group for Check Point Firewall-1 users and implementers. Contains the Check Point Wikipedia, discussion groups and other useful information.
http://www.cpug.org/

Firewall-net
Provides security and firewall comparisons, compare tools, configuration tips. Also includes a user forum.
http://www.firewall-net.com/

Lenny Zeltser Firewall Discussions
Explores the use of various firewall techniques for protecting resources according to business requirements of multi-tier applications.
http://www.zeltser.com/multi-firewall/

Lowth.com
Linux security and related software articles and tools.
http://www.lowth.com/

ISC Firewalls Mailing List
For discussions of Internet firewall security systems and related issues. Also features searchable archives and digests.
http://www.isc.org/ops/lists/firewalls/

Firewall Tutorial
A fairly concise (< 4000 words) document for readers who want to know more about what firewalls do. Comprehensively covers main firewall concepts and technologies.
http://www.ipcortex.co.uk/wp/fw.rhtm

InfoSysSec: Firewall Security and the Internet
A portal for professionals, features links, FAQs, tutorials, product information, magazine articles and downloads.
http://www.infosyssec.com/infosyssec/security/firew1.htm

Securepoint Firewall Archives
Searchable archives of the mailing list and forums on a range of different firewalls and related items.
http://securepoint.com/lists/html/

Korvan's Web
How to build an OpenBSD firewall for use with Australian broadband ISPs (Telstra and Optus, cable and ADSL).
http://lehman.id.au/obsd-fw

Attack Prevention
A web log style site consisting of articles, papers and news relating to security information.
http://www.attackprevention.com/

Firewall Software
A weblog dedicated to computer and firewall security. Contains definitions and explanations.
http://firewall_software.blogspot.com/

Workable passive FTP connections through a firewall
A general article on enabling passive FTP connections through a firewall. Examples used in the article discuss the APF firewall and Pure-FTPD ftp server.
http://www.theserverpages.com/articles/servers/cpanel/tweaks/Getting_passive_FTP_connections_to_work_through_a_firewall_properly.html

How-to setup an APF Firewall
A how-to that covers the basics and some advanced topics of installing and configuring the firewall, especially for CPanel users.
http://www.theserverpages.com/articles/servers/cpanel/security/How-to_setup_an_APF_Firewall.html

Sunshadowz Security Tips
Home computer security tips for firewalls, anti-virus, spyware removal, data encryption and intrusion detection, identity theft, debit and credit card scams and child safety online.
http://www.sunshadowz.com/

Halted Firewalls Article
An article from SysAdmin magazine discussion of technique and possible applications for halted firewalls.
http://www.samag.com/documents/s=1824/sam0201d/0201d.htm