SSH Mastery: OpenSSH, PuTTY, Tunnels and Keys
Michael W Lucas
C++ Crash Course
Josh Lospinoso
Cyber Security and Network Security
Sabyasachi Pramanik & Debabrata Samanta & M. Vinay & Abhijit Guha
Ethical Hacker’s Penetration Testing Guide
Samir Kumar Rakshit
Pluggable Authentication Modules
Kenneth Geisshirt