John the Ripper – A well know password-cracking utility for Linux, Mac OS X, and Windows.
Kali Linux – Kali Linux is a Debian-based Linux distribution that allows you to engage in digital forensics and penetration testing.
Web Security Dojo – A free open-source self-contained training environment for Web Application Security penetration testing.
Wireshark – Wireshark is a free and open-source packet analyzer. It is used for network troubleshooting, analysis, software and communications protocol development, and education.
Tor Browser – Tor is free and open-source software for enabling anonymous communication.
Burp Suite Community Edition – A set of manual tools for exploring web security. Proxy your HTTPS traffic, edit and repeat requests, decode data, and more.