How this course works

The route

You can begin without Linux or cybersecurity experience. The course has three parts. Foundations introduces computers, the command line, code, networks and the web. Security core introduces security ideas, testing tools, web weaknesses, cryptography and file analysis, then a first capture-the-flag (CTF) event: a set of security puzzles. Going deeper teaches you to plan and interpret a complete lab test. Its optional Reversing and Pwn stages introduce reading compiled programs and reasoning about memory errors after First CTF.

Every lesson is open on the first visit. Nothing is locked, and a lesson lists the reading it recommends first. The course map shows the arcs, and the first stage begins at What this website is.

What a lesson looks like

A lesson introduces a situation and a skill to practice. Its setup card lists recommended reading, estimated reading and activity time, the working environment, and an alternative for learning without a lab. Read the worked example, then follow the activity using its own evidence. Text, code listings, diagrams and step-by-step visuals explain the idea. The lesson also includes checks, common mistakes, practice links and references.

How checks work

A check asks you to use what the lesson teaches. Depending on the lesson, you type an answer, choose one or more options, put steps in order, or match rows. Follow the question's answer format and select Check. For lessons with several checks, completion is recorded when every required check has a correct, saved answer. Optional checks do not count toward completion. An older saved completion remains valid when checks change.

An incorrect answer shows Not yet and opens the next hint. A blank answer, or a matching check with an unanswered row, does not use an attempt or open a hint. Ordering checks start with a filled list that you can rearrange before checking. After three incorrect attempts, Show the answer becomes available. Revealing the answer does not record completion; you can still submit an answer afterward. Checking happens in your browser and requires JavaScript over HTTPS or a local developer preview on localhost. These checks give practice feedback; they do not verify that you ran a tool or completed a lab.

Evidence labels

Read the captions and evidence labels before interpreting a listing or diagram. An owned fixture is an original file made for this course. A saved trace is recorded output that you can inspect without repeating the original run. A model illustrates an idea. A sketch resembles tool output but was written as an example. Expected or predicted results describe what an activity should produce; they are not proof of a fresh run.

Your progress

There is no account or automatic sync between devices. When browser storage is available, this browser saves your completed checks and the last lesson you opened. The dashboard offers a lesson to continue and lets you export progress to a file. Import that file in another browser to copy your progress there. Importing keeps existing completions and adds those from the file. Clearing this site's browser data removes the local save. If a correct answer cannot be saved, allow this site's browser storage and select Retry saving, or note where you stopped.

Where you may practice

Use the course's files, your own isolated labs, or targets that a practice platform explicitly assigns to you. Follow the allowed targets and actions for each activity. The Practice page lists external resources and recommended reading. Before testing any other system, obtain written permission that covers the target and the test you intend to run.