Disclaimer: I am not a pen tester!
(but I did take a course on it)
Learning Resources
Cybrary Free with many many security courses, like Pen Test and Ethical Hacking
https://pentesterlab.com/
SANS Cheat Sheet blog post
PWNPi 'The Pen Test Drop Box Distro for the Raspberry Pi'
https://pentesting.site/ lots of tools, and cheat sheets
Tools
Last updated