1. CERT Coordination Center
2. Computer Security Resource Center (NIST's Computer Security Division)
3. Counterpane
4. Network Associates
5. RSA Lab
6. VeriSign

B. Other security courses in the world (sorry, this is incomplete)

1. Computer Security by David Aspinall, School of Informatics, University of Edinburgh.
2. Network Security Protocols by Radia Perlman, Harvard University.
3. Security Protocols by John Mitchell, Stanford University.
4. Computer Security by Matt Bishop, UC/Davis.
5. Network Security by Angelos Keromytis, Columbia University.
6. Internet Security by Engin Kirda and Christopher Kruegel, Technical University of Vienna
7. Advanced Internet Security by Engin Kirda and Christopher Kruegel, Technical University of Vienna

C. Software tools

General TCP/IP security

S. Bellovin, "Security Problems in the TCP/IP Protocol Suite," ACM CCR, vol. 19, no. 2, pp. 32-48, 1989.
S. Bellovin, "A Look back at 'Security Problems in the TCP/IP Protocol Suite'",

Public Key Infrastructure (PKI)

Main RFC for PKI:

1. R. Housley, W. Ford, W. Polk, D. Solo, "Internet X.509 Public Key Infrastructure Certificate and CRL Profile," RFC 2459,  January 1999.
2. A. Aresenault, and S. Turner, "Internet X.509 Public Key Infrastructure," Internet draft, draft-ietf-pkix-roadmap-06.txt, Nov. 2000.

1. The (US) NIST Public Key Infrastructure Program
2. RSA Security's Public-Key Cryptography Standards Homepage
3. Understanding PKI
4. C. Ellison and B. Schneier, "Ten Risks of PKI: What You're Not Being Told About Public Key Infrastructure," Computer Security Journal, v 16, n 1, 2000, pp. 1-7.
5. R. Perlman, "An Overview of PKI Trust Models," IEEE Network Magazine, pp. 38-43, Nov/Dec, 1999.
6. J. Linn, "Trust Models and Management in Public-Key Infrastructures," RSA report, Nov. 2000.
7. The PKI Page

IPSec

Main RFC documents for IPSec:

1. S. Kent, “Security Architecture for the Internet Protocol,” RFC2401, Nov. 1998.
2. S. Kent and R. Atkinson, “IP Authentication Header,” RFC2402, Nov. 1998.
3. S. Kent and R. Atkinson, “IP Encapsulation Security Payload (ESP),” RFC2406, Nov. 1998.
4. R. Thayer, N. Doraswamy, and R. Glenn, "IP Security Document Roadmap," RFC2411, Nov. 1998.

1. D. Maughan, M. Schertler, M. Schneider, and J. Turner, "Internet Security Association and Key Management Protocol
(ISAKMP)," RFC2408, Nov. 1998.
2. H. Orman, "The OAKLEY Key Determination Protocol. H. Orman," RFC 2412, Nov. 1998.
3. D. Harkins and D. Carrel, "The Internet Key Exchange (IKE)." RFC2409, Nov. 1998.
4. D. Piper, "The Internet IP Security Domain of Interpretation for ISAKMP," RFC2407, Nov. 1998.

1. C. Madson and R. Glenn, "The Use of HMAC-MD5-96 within ESP and AH," RFC2403, Nov. 1998.
2. C. Madson and R. Glenn, "The Use of HMAC-SHA-1-96 within ESP and AH," RFC2404, Nov. 1998.
3. C. Madson and N. Doraswamy, "The ESP DES-CBC Cipher Algorithm With Explicit IV," RFC2405, Nov. 1998
4. Advanced Encryption System (AES)

1. IPSec for FreeBSD
2. IPSec Tunneling Between FreeBSD Hosts
3. An IPSec Reference Implementation for Linux
4. IPSec FAQ

Main RFC and nonRFC documents for TLS or SSL:

1. T. Dierks, C. Allen, "The TLS Protocol Version 1.0," RFC 2246,  January 1999.
2. SSL 3.0 Specification

1. D. Wagner and B. Schneier, "Analysis of the SSL 3.0 Protocol," The Second USENIX Workshop on Electronic Commerce Proceedings, USENIX Press, November 1996, pp. 29-40.
2. G. Apostolopoulos, V. Peris, and D. Saha, "Transport Layer Security: How Much Does It Really Cost?" Proc. IEEE INFOCOM, 1999.
3. L. Paulson, "Imductive Analysis of the Internet Protocol TLS," ACM Trans. Information and System Security, vol. 2, no. 3, Aug, 1999, pp. 332-351.