A very interesting challenge is Try2Hack. There are different levels and your goal is always to find out a password. It's getting harder from level to level and you learn a lot on the way.
I'm currently on level 6.
Solutions
WARNING: Do not click on the link above if you want to play the game yourself. The link is named "Solutions" because it really contains the detailed descriptions how I solved the levels. It really takes the fun out of it for you but I need this for my ego ;-)
Please do not send me detailed descriptions how to solve the level where I'm currently on. I want to find it out on my own. Thanks.
