Designing and Implementing Linux Firewalls with QoS Using Netfilter, ...
Lucian Gheorghe
Learning Shell Scripting with Zsh
Gastón Festari
Quick Start Guide to Penetration Testing
Sagar Rahalkar
Mastering Linux Network Administration
Jay LaCroix
Linux Advanced Routing and Traffic Control HOWTO
Gregory Maxwell & Remco Mook & Martijn Oosterhout & Paul Schroeder & Jasper Spaans & Bert Hubert