Lesson 6.2: Capture the flag, and taking notes like a professional
What capture-the-flag competitions are (jeopardy and attack-defence), how flags work, and why encoding is not encryption. Then the skill that every report, every exam and every investigation depends on: notes you can repeat from. In the lab you solve a small four-flag challenge with commands you already know (hidden files, base64, grep, sha256sum) and turn your shell history into the start of a write-up.
17 min
You will learn to
- Explain jeopardy and attack-defence CTFs
- Tell encoding, encryption and hashing apart
- Find flags with ls -a, base64, grep and sha256sum
- Keep notes that let someone repeat your work
- Know CTF etiquette
Key terms
- Capture the flag (CTF)
- A security competition where you solve challenges to find secret strings called flags.
- Flag
- The secret string that proves you solved a challenge, in a fixed format.
- Encoding
- Writing data in another form so it can be stored or sent; reversible by anyone, no key.
- Encryption
- Scrambling data so only someone with the key can read it.
- Write-up
- A step-by-step account of how a challenge was solved, written after it ends.
- Methodology
- A repeatable order of steps you follow on every target.
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