General network security
CERT
Dave Dittrich's Web page with lots of security related links
Cryptography resources
Distributed denial-of-service
Dave Dittrich's DDoS page
Worms
Wormblog.com - A blog about the worm problem, technology, detection and defenses
Networm.org - Worm Information Center
eEye Digital Security - Worm research and some disassembled worms
LSD research group - C code for some common exploits
Conferences and journals
IEEE Security and Privacy Magazine
IEEE Transactions on Dependable and Secure Computing
New Security Paradigms Workshop
INFOCOM
SIGCOMM
Network and Distributed System Security Symposium