I’ve decided to compile a list of fun and educational IT challenges out there.  Any challenge on this list I have either completed, or I’m still trying to complete in my spare time 🙂

CryptopalsSolve cryptography challenges derived from weaknesses in real-world systems and modern cryptographic constructions. Use any programming language you wish.https://cryptopals.com
BanditSolve Linux-related challenges as you try to find the location of the ssh key to get to the next level. Early levels are very easy, and beginner-friendly, but the difficulty ramps up as you get further into the game.https://overthewire.org/wargames/bandit/