Please share with us a link to a resource you have found helpful to learn more about penetration testing. Mine is the Cyber Plumbers Handbook: https://github.com/opsdisk/the_cyber_plumbers_handbook/

From the author: “This book is packed with practical and real world examples of SSH tunneling and port redirection in multiple realistic scenarios. It walks you through the basics of SSH tunneling (both local and remote port forwards), SOCKS proxies, port redirection, and how to utilize them with other tools like proxychains, nmap, Metasploit, and web browsers.

Advanced topics included SSHing through 4 jump boxes, throwing exploits through SSH tunnels, scanning assets using proxychains and Metasploit's Meterpreter, browsing the Internet through a SOCKS proxy, utilizing proxychains and nmap to scan targets, and leveraging Metasploit's Meterpreter portfwd command.”