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Extrusion Detection: Security Monitoring for Internal IntrusionsExtrusion Detection: Security Monitoring for Internal Intrusions by Richard Bejtlich
Buy new: $34.64 / Used from: $23.10
Detecting the "Enemy at the Watercooler" - seeing what people on the inside wish to do...
The Tao of Network Security Monitoring: Beyond Intrusion DetectionThe Tao of Network Security Monitoring: Beyond Intrusion Detection by Richard Bejtlich
Buy new: $44.09 / Used from: $31.95
A very solid text on intrusion detection, albeit in favor a little too much to FreeBSD
Snort IDS and IPS Toolkit (Jay Beale's Open Source Security)Snort IDS and IPS Toolkit (Jay Beale's Open Source Security) by Brian Caswell
Buy new: $32.97 / Used from: $26.92
Great to learn about rules based IDS systems
Thinking Strategically: The Competitive Edge in Business, Politics, and Everyday LifeThinking Strategically: The Competitive Edge in Business, Politics, and Everyday Life by Avinash K. Dixit
Buy new: $12.89 / Used from: $6.60
Learning to see the big picture and effectively strategize
Network Analysis, Architecture and Design, Second Edition (The Morgan Kaufmann Series in Networking)Network Analysis, Architecture and Design, Second Edition (The Morgan Kaufmann Series in Networking) by James D. McCabe
Buy used from: $9.90
A fantastic text on the subject
Counter Hack Reloaded: A Step-by-Step Guide to Computer Attacks and Effective Defenses (2nd Edition)Counter Hack Reloaded: A Step-by-Step Guide to Computer Attacks and Effective Defenses (2nd Edition) by Edward Skoudis
Buy new: $40.94 / Used from: $33.99
I am not a big fan of most books with "hacking" in the title, but there are a few exceptions
Hacking Exposed 5th Edition: Network Security Secrets And SolutionsHacking Exposed 5th Edition: Network Security Secrets And Solutions by Stuart McClure
Buy new: $31.49 / Used from: $2.54
A bit dated at times, but still an excellent reference
Gray Hat Hacking : The Ethical Hacker's HandbookGray Hat Hacking : The Ethical Hacker's Handbook by Shon Harris
Buy used from: $4.99
One of my favorites on the subject
TCP/IP Illustrated, Volume 1: The ProtocolsTCP/IP Illustrated, Volume 1: The Protocols by W. Richard Stevens
Buy new: $51.60 / Used from: $11.39
You have to know the guts of what you are working with!
Wireless HacksWireless Hacks by Rob Flickenger
Buy new: $16.47 / Used from: $5.02
A fun and entertaining text
Google Hacks: Tips & Tools for Finding and Using the World's InformationGoogle Hacks: Tips & Tools for Finding and Using the World's Information by Rael Dornfest
Buy new: $16.49 / Used from: $8.00
Who wouldn't want to be able to wield a 10 pound sledge hammer?
The Art of Intrusion: The Real Stories Behind the Exploits of Hackers, Intruders and DeceiversThe Art of Intrusion: The Real Stories Behind the Exploits of Hackers, Intruders and Deceivers by Kevin D. Mitnick
Buy new: $22.00 / Used from: $4.49
Shows that someone with moderate technical skills but excellent social skills can rule the hacking world.... Kevin Mitnick was exceptional at the people hack, and then leveraged his technical skills to become one of the most famous hackers alive.
Reversing: Secrets of Reverse EngineeringReversing: Secrets of Reverse Engineering by Eldad Eilam
Buy new: $26.40 / Used from: $20.44
Learn to do it... seriously...
C Programming Language (2nd Edition)C Programming Language (2nd Edition) by Brian W. Kernighan
Buy new: $46.42 / Used from: $19.89
One of the few texts I still use frequently...
The C++ Standard Library: A Tutorial and ReferenceThe C++ Standard Library: A Tutorial and Reference by Nicolai M. Josuttis
Buy new: $67.72 / Used from: $19.88
Live it, and learn it! You can't hack if you can't program
The C++ Programming Language: Special EditionThe C++ Programming Language: Special Edition by Bjarne Stroustrup
Buy new: $52.15 / Used from: $18.99
A highly recommended, albeit complex, text on C++ programming
Programming Ruby: The Pragmatic Programmers' Guide, Second EditionProgramming Ruby: The Pragmatic Programmers' Guide, Second Edition by Dave Thomas
Buy new: $20.71 / Used from: $3.69
Learn a scripting language. PHP, PERL, and others are great, I am a big fan today of Ruby.
Security WarriorSecurity Warrior by Cyrus Peikari
Buy new: $29.67 / Used from: $10.50
An enlightening text on various security tools and their usage
Official (ISC)2 Guide to the CISSP CBK ((Isc)2 Press Series)Official (ISC)2 Guide to the CISSP CBK ((Isc)2 Press Series)
Buy new: $59.16 / Used from: $45.00
Might as well get certified before you end up certifiable!