Offensive Security is a great option. For pen testing specifically: https://www.offensive-security.com/information-security-training/penetration-testing-trainin

Offensive Security is a great option. For pen testing specifically: https://www.offensive-security.com/information-security-training/penetration-testing-training-kali-linux/ https://www.offensive-security.com/information-security-trai... You should know stuff like basic TCP/IP before you hop into any technical side of security.