Discover - Custom bash scripts used to automate various penetration testing tasks including recon, scanning, parsing, and creating malicious payloads and listeners with Metasploit.

Veil - Veil is a tool designed to generate metasploit payloads that bypass common anti-virus solutions.

Holistic Infosec - Lots of good pentesting tools available here.

GTFObins - The project collects legitimate functions of Unix binaries that can be abused to break out restricted shells, escalate or maintain elevated privileges, transfer files, spawn bind and reverse shells, and facilitate the other post-exploitation tasks.

Wordlists and passwords. Pretty important stuff.

A very detailed article on how and what attackers do on compromised linux boxes.

This is probably the best article on hacking