Bash Idioms: Write Powerful, Flexible, Readable Shell Scripts
Carl Albing & J P Vossen
Iptables Tutorial 1.2.2
Oskar Andreasson
Cross-Site Scripting Attacks: Classification, Attack, and Countermeasures
B. B. Gupta and Pooja Chaudhary
The Wireshark Field Guide
Robert Shimonski
Cyber Security and Network Security
Sabyasachi Pramanik & Debabrata Samanta & M. Vinay & Abhijit Guha
GitHub For Dummies
Sarah Guthals & Phil Haack
Linux Bible (10th edition)
Christopher Negus