Wireless Hacking with Kali Linux
Hugo Hoffman
Mastering Linux Administration
Alexandru Calcatinge & Julian Balog
SSH Mastery: OpenSSH, PuTTY, Tunnels and Keys
Michael W Lucas
Nmap Network Scanning
Gordon Lyon
Linux Advanced Routing and Traffic Control HOWTO
Gregory Maxwell & Remco Mook & Martijn Oosterhout & Paul Schroeder & Jasper Spaans & Bert Hubert