SecurityFocus Intrusion detection focus area; designed to assist discussion on security related topics, and provides a comprehensive database of security knowledge and resources. It also hosts the BUGTRAQ mailing list. http://www.securityfocus.com/ids

Linux Security IDS An excellent source of IDS-related information, including security best practices, audit procedures, penetration testing, community information and more. http://www.Linux-Sec.net/IDS/

DShield Distributed Intrusion Detection System. Submit your own firewall log excerpts or browse through current activity reported to the system. Features a list of the "most wanted" abusive IP addresses. http://www.dshield.org/

Talisker Security Products and Services Large index of computer security resources, including a glossary of Intrusion Detection and Prevention systems. http://www.networkintrusion.co.uk

LinuxSecurity IDS Resources Comprehensive collection of IDS-related resources made available by the linuxsecurity.com community. http://www.linuxsecurity.com/resources/intrusion_detection-1.html

Security Resources for Windows Network Administrators Provides books, articles, software and other information on penetration testing and other security issues. Geared toward Windows NT/2000/XP Network Administrators. http://is-it-true.org/pt/

Intrusion Detection System Resources Comprehensive collection of tutorials, product reviews, general information and other resources dealing with Intrusion Detection and Prevention Systems. http://is-it-true.org/fw/fwtips6.shtml

Internet Storm Center Operated by the SANS Institute, the ISC provides a user-supported infrastructure for intrusion detection systems to share information about ongoing attacks that span countries, networks, and administrative boundaries. http://isc.incidents.org

Michael Sobirey's IDS Page An excellent index of most currently available IDS and IPS products, including vendor contact information. http://www.cse.sc.edu/research/isl/mirrorSobireys.shtml

COAST Intrusion Detection Hostlist Clearinghouse listing of many of the Internet resources associated with intrusion detection and prevention systems. Includes inventories of commercial products, research projects, and other IDS-centric material. http://www.cerias.purdue.edu/about/history/coast_resources/intrusion_detection/

Security Library Collection of detailed technical papers on focusing on TCP networks, Intrusion Detection Systems, firewall protection and more. http://www.seclib.com/seclib/

Privacyware Intrusion Prevention and Detection Extends the capabilities of conventional security systems to help manage threats more efficiently and effectively. Includes a wide array of intrusion detection and analysis tools for Windows servers. http://www.privacyware.com

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