Advanced reading and reference books for network security course, organized per topic:

Cryptography:

Cryptography: Theory and Practice
by Douglas Stinson, CRC Press, 2nd edition, Chapman-Hall, 2002

A Course in Number Theory and Cryptography
by Neal Koblitz, Springer-Verlag, 1987

Cryptanalysis of Number Theoretic Ciphers
by Samuel S., Jr. Wagstaff, Mikhail J. Atallah, Chapman-Hall, CRC, 1st edition, 2002

Reference Books:

Applied Cryptography: Protocols, Algorithms, and Source Code in C
by Bruce Schneier, Wiley; 2 edition, 1995

Handbook of Applied Cryptography
by Alfred J. Menezes, et al., CRC Press, 1996

General Network Security:

Network Security: Private Communication in a Public World
Prentice Hall PTR; 2 edition, 2002

Cryptography and Network Security: Principles and Practice
Prentice Hall, 3rd edition, 2002

Basics of Network Security: Network Security Essentials (2nd Edition)
Prentice Hall; 2 edition, 2002
Networking:

Computer Networking : A Top-Down Approach Featuring the Internet (3rd Edition)
by James F. Kurose, Keith W. Ross, Addison Wesley, 3 edition, 2004

Computer Networks: A Systems Approach, 3rd Edition
by Larry L. Peterson, Bruce S. Davie, Morgan Kaufmann, 3 edition, 2003
Counter Hacking:

Counter Hack: A Step-by-Step Guide to Computer Attacks and Effective Defenses
Prentice Hall PTR; 1st edition, 2001

Hacking Exposed: Network Security Secrets & Solutions
by Stuart McClure, Joel Scambray, George Kurtz, McGraw-Hill Osborne Media, 4 edition, 2003

Practical Intrusion Detection: Inside Network Perimeter Security: The Definitive Guide to Firewalls, Virtual Private Networks (VPNs), Routers, and Intrusion Detection Systems
by Stephen Northcutt, Lenny Zeltser, Scott Winters, Karen Fredrick, Ronald W. Ritchey, Sams; 1st edition, 2002
Advanced Cryptography Books:

Differential cryptanalysis of the data encryption standard
by Eli Biham, Springer-Verlag, 1993

Modern Cryptography, Probabilistic Proofs and Pseudorandomness
by Oded Goldreich, Springer-Verlag, 1st edition, 1999