The Cybersecurity Self-Help Guide
ARUN. SONI
Zabbix 5 IT Infrastructure Monitoring Cookbook
Nathan Liefting & Brian van Baekel
Iptables Tutorial 1.2.2
Oskar Andreasson
SSH Mastery: OpenSSH, PuTTY, Tunnels and Keys
Michael W Lucas
Linux Advanced Routing and Traffic Control HOWTO
Gregory Maxwell & Remco Mook & Martijn Oosterhout & Paul Schroeder & Jasper Spaans & Bert Hubert