OverTheWire
Free security wargames played over SSH in a real shell
OverTheWire hosts a set of free security wargames that you play in a real Linux shell. You connect to each game's server over SSH from your own terminal. At each level you find the password for the next level, so the games get harder step by step.
Free · No login · SSH · Intermediate
About OverTheWire
The games cover different topics. Bandit teaches Linux basics. Natas covers web security, Krypton covers cryptography, and games like Narnia and Behemoth move into reverse engineering and binary exploitation.
It suits beginners who start with Bandit, and goes up to advanced players. No account is needed. The rules ask you not to publish level passwords, and you should clean up any files you create on the servers.
On Breakpoint since 23 Oct 2026.