Linux in a Nutshell
Arnold Robbins & Ellen Siever & Stephen Figgins & Robert Love
Metasploit Penetration Testing Cookbook
Abhinav Singh
Linux® Command Line and Shell Scripting Bible
Richard Blum
Beginning Linux Programming
Neil Matthew & Richard Stones
Unauthorised Access
Wil Allsopp
Cryptography Engineering
Niels Ferguson & Bruce Schneier & Tadayoshi Kohno