AIDE - Advanced Intrusion Detection Environment - AIDE (Advanced Intrusion Detection Environment) is a free replacement for Tripwire. It does the same things as the semi-free Tripwire and more.
Bastille-linux - An initiative to build a secure Linux distribution.
The Bunker - Britain's ultimate safe house - The authors who wrote Apache SSL for free also run "The Bunker" real nuclear bunker, built to withstand a direct nuclear strike. It has been purchased from the Government by A. L. Digital Secure Hosting & Facilities Management, they protect servers against all known physical threats!
Crypto Law Survey - Bert-Jaap Koops homepage on several countries' cryptography export laws.
cryptoarchive.net - Here you will find a large repository of Open Source cryptographic software (over 3 GB).
Dejavo EasyChains - EasyChains is a very easy-to-use GUI for the console firewall script. It makes it easy to make a custom firewall using the script generator or you can add custom rules and remove rules from a numbered list.
The ECHELON System - About the NSA's system of eavesdropping on worldwide electronic messages.
Encryption solutions with Mandrake - MandrakeSoft has released a set of cryptographic packages that cannot be distributed or redistributed from the USA and from several European countries. All those packages have been uploaded to unrestricted servers.
Firewall over Web, Hali Tower Notices - As the name says: linux-firewall-tools, to be more clear this site allows you to configure your linux ipchains according to your needs over a web site based Q&A interface. Nice and easy.
Fresh Free FiSSH - Free SSH client for 95/NT4, currently in development.
Geheimnis - Geheimnis is a KDE application that "wraps" around encryption programs and their irksome command-line interface, making it easier for users to use these programs.
gfcc: GTK+ Firwall Control Center - gfcc (GTK+ Firewall Control Center) is a GTK+ application which can control Linux firewall policies and rules, based on ipchains package.
Gnome PG - Gnome Privacy Guard, is still under developement
ICSA - Independent association offering objective views and opinions on computer security issues. Improve computer security through knowledge sharing, information dissemination, and security products certification.
Insecure.org - Site highlighting the exploits available in unsafe systems. Fyodor's page of Computer Security and Hacking Tools Papers Exploits GNU Nmap Stealth Port Scanner Linux Freebsd and Solaris Information
mason - Mason is a tool that interactively builds a firewall using Linux' ipfwadm or ipchains firewalling. You leave mason running on the firewall machine while you are making all the kinds of connections that you want the firewall to support (and want it to block). Mason gives you a list of firewall rules that exactly allow and block those connections. It can either build a firewall from scratch for you or supplement an existing firewall.
mod_ssl: The Apache Web Server Interface to OpenSSL - The module provides strong cryptography for the Apache 1.3 webserver via SSL and TLS protocols, it was developed using OpenSSL, which is based on SSLeay. [Free / Open Source] (Ralf Engelschall, Ben Laurie)
Peter Gutmann's link farm - Want a lot of links to security and crypto related stuff? Try here - if you don't find what you want, it probably doesn't exist!
The PGP Forwarding Server - The PGP Forwarding Server is a server that receives e-mail on behalf of a user, encrypt it automatically and sent it off the users' real e-mail account.
Pseudonym Security - This is a good "Secure Sockets Layer" reading point for someone who is familiar with the Web, HTTP, and Web servers but is not a security expert.
PuTTY - PuTTY is a free implementation client of Telnet and SSH for Win32 platforms, written and maintained primarily by Simon Tatham.
Secure Rememberable Passwords - PassMaker is a free site that creates passwords which are easy to remember, pronounce and secure on-line. The passwords can easily be remembered because they are composed of two or more pronounceable words joined by special characters. They are secure because they are comprised of three or more components.
Security Focus - Online magazine providing news and editorials on security related topics, along with a comprehensive database of security knowledge. This site hosts the BUGTRAQ mailing list.
SecurityPortal.com - Web site developed and funded by AIS, dedicated to providing corporate security professionals with the information and resources needed to protect their networks.
TTSSH: An SSH Extension to Teraterm - A freely available method to create an ssh client for Windows 95 and Windows NT. It is based on extending the Teraterm terminal emulator.