General security:

Electronic Frontier Foundation; Security Corner; securityfocus; Hacker News Network; Security Bugware; NTSecurity; NTsecurity.nu; Packet Storm; Computer Security Institute; Yahoo Security/Encryption; Intrusion detection

Cryptography:

RSA, Rsa Labs, Security Dynamics, Counterpane, Cryptography FAQ

SPEKE, SRP-3

Hacking:

Firewalls:

Raptor "Eagle", Gauntlet, Cisco Pix, CyberGuard, Lucent, Check Point

Tools, exploits:

insecure.org (NMAP); cotse.com; greymagic; Shadow security scanner; ISS system scanner; Ethereal protocol analyzer; Foundstone tools collection

Advisories:

Computer Emergency Response Team (CERT); CERT advisories; Security Focus; NTBugtraq; CVE common vulnerabilites and exposures; Cisco advisories; @stake advisories; MS Security Notification Service; MS advisory mailing list; SANS institute newsbites; incidents.org

Certification:

Other info:

NSA security recommendations; Tempest, NEC Socks info, SSL v.3, Kerberos; Junkbusters (privacy info), IIS 4.0 security checklist (view using IE)