Book Recommendations

General

O'Reilly System Administration Series

Essential System Administration

O'Reilly Security Series

Practical UNIX Security: An excellent introduction to UNIX security. Covers a wide range of topics. An excellent starting point for anyone interested in security and keeping themselves safe.

Computer Security Basics: Security handbook outlining trusted systems, cryptography, mandatory access control. Covers the orange book and government security requirements.

Network Security PRIVATE Communication in a PUBLIC World
Kaufman/Perlman/Spencer, Prentice Hall Publishing: A first-rate comprehensive introduction on public/private key cryptography, hashes, authentication mechanisms, kerberos V4/V5, email security (PEM, PGP.) Discusses details of the mechanisms
This is one of the best books on network security. A must for anyone with more than a casual interest in network security.

Computer Security Third Edition
John M Carrol, Butterworth/Heinmann Publishing: Good book on corporate and goverment EDP (Electronic Data Protection) Policies. Methods of Electronic and Physical security, staff screening, building layouts, etc. Gives a good feel for "real" security policies. Much of this book goes far beyond anything that will be needed at all but the higher levels of protection.

TCP/IP programming

Internetworking fwith TCP/IP Vol I - Principles, Protocols and Architecture
Douglas E. Comer, Prentice Hall Publishing: Excellent survey of TCP/IP components and principles. Less technical and easier to read than the Stevens series. An excellent first book for those who want to learn how TCP/IP works.

Internetworking fwith TCP/IP Vol II - Design, Implementation, and Internals
Douglas E. Comer, Prentice Hall Publishing: Continuation of Volume I with code examples. Covers much in-depth concepts than Volume I such as interaction of different algorithms.

Internetworking with TCP/IP Vol III - Client-Server Programming and Applications
Douglas E. Comer, Prentice Hall Publishing: Teaches how to write client-server applications. Covers RPC and other tools for program interaction. This is the building block for distributed systems programming.

TCP/IP Illustratred Vol 1 - The Protocols
W. Richard Stevens, Addison-Wesley Publishing: The authoritative guile for TCP/IP. Completely covers the protocols in-depth right down to exactly what bits are in the packets. Anyone who wants to understand TCP/IP internals needs to read this book.

TCP/IP Illustratred Vol 2 - Implementation
Gary R. Wright/W. Richard Stevens, Addison-Wesley Publishing: You've read volume 1 and know how everything works. This book teaches you how to code it from scratch. Real TCP/IP hackers own a copy and keep it nearby at all times.

TCP/IP Network Programming
W. Richard Stevens - Prentice Hall Publishing: Detailed tutorial on Berkeley sockets, file transfer, RPC, printing, time servers, etc. In-depth examples and soure code for many real TCP/IP appliations.

Cryptography

Applied Cryptography Second Edition
Bruce Schneider, Wiley and Sons Publishing: Second edition of the book the NSA never wanted published. The first, last and only book one will have to read on cryptography. Over 700 pages of cryptographic protocols, techniques, and algorithms. Complete with source code in C for just about every algorithm discussed.

The Codebreakers - The story of secret writing
David Kahn, Scribner Publishing: History of cryptography from the beginnings til the present day. Gives a fascinating look how the huge role cryptography played in history. Non-technical and very good reading.