Linux iptables Pocket Reference
Gregor N. Purdy
Quick Start Guide to Penetration Testing
Sagar Rahalkar
The Wireshark Field Guide
Robert Shimonski
Kubernetes: Up and Running
Kelsey Hightower & Brendan Burns & Joe Beda & Lachlan Evenson
Bash Idioms: Write Powerful, Flexible, Readable Shell Scripts
Carl Albing & J P Vossen