Here are my links
- OtW’s easiest Wargame
I did 20 levels during the holiday, and they helped me understand basic unix commands.
- Cryptohack
This is where I learned cryptography. Mostly for my CtFs but kind of useful for OS anyway.
3.Regex Cheat Sheet
While not exactly the most readable, it does come in quite handy at times.
- Linux Cheat Sheet
Provide most essential linux commands. Comes in quite handy at times.
- Cryptography Checklist
A list of essential tools used in modern day cryptography. Kind of useful for ctfs.
- School of Rop
A learning based web for ctfs training.