Information Technology Security Reading is a subjective subject. Here are some recognised quality reading sources.

Counter Hack: A Step-by-Step Guide to Computer Attacks and Effective Defences by Ed Skoudis (Author)

Mastering Network Security by Chris Brenton, Cameron Hunt

Intrusion Signatures and Analysis by Mark Cooper, Stephen Northcutt, Matt Fearnow, Karen Frederick

Hackers Beware: The Ultimate Guide to Network Security by Eric Cole

SANS GIAC Certification: Security Essentials Toolkit (GSEC) by Eric Cole (Author),

The Protocols (TCP/IP Illustrated, Volume 1) by Richard Stevens

http://security.oreilly.com/

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