Linux Essentials

This track is about driving a Linux system from the command line: moving around the file system, reading what is in it, and controlling who can do what to it. Seven lessons take you from the first prompt to the commands defenders reach for every day, such as grep for finding a needle in a log and chmod for locking down a file that should not be world-readable.

Every lesson is hands-on on your own machine. macOS and native Linux work directly, and Windows users can follow along inside WSL, so there is no VM to set up, and no admin rights are needed for the lessons themselves (Windows users need admin rights once, to install WSL). Type the commands yourself rather than just reading them, because the muscle memory is the point.

The skills here show up constantly in real security work: reading logs on a server, triaging a misbehaving process, and checking why a file or directory is accessible to someone it should not be. When a question goes beyond what the lessons cover, take it to the community Discord, where the longer conversations happen.