Security.

• CERT Coordination Center
• Crypto-Gram : Bruce Schneier's monthly newsletter
• SecurityFocus : Bugtraq and other mailing lists
• Talisker's Intrusion Detection System List
: List of tools for professionals

Free Software and documentation.

• Apache webserver
• Debian GNU/Linux -- The Universal Operating System
• Exim Mail Transfer Agent
• FreeS/WAN project : VPN software for GNU/Linux
• Free Software Foundation
• OpenBSD : the best BSD UNIX qua security
• OpenLDAP Lightweight Directory Access Protocol
• ProFTP FTP server
• SuSE Linux : for mainframes, PPC, Sparc, Alpha and x86 cpu's
• T-DOSE : promotion event for use and development of Open Source Software in Eindhoven (NL)
• The TinyCOBOL Project Home Page , a nice tiny COBOL compiler

Anti-SPAM

• Anti-Spam Tools & Resources
• Spam Cop - File a spam report

Other links.

• Linux on the IBM 370/390 Architecture: as it started.
• Address and route map Mobach - Echteld and others.
• Systemhouse Mobach bv (Dutch)
• Safe Harbour for encumbered Free and Open Source software and links