{
  "id": "linux-permissions-mcq",
  "title": "Choosing the Minimal Permission",
  "category": "Linux Fundamentals",
  "isolation_type": "shared_namespace",
  "difficulty": "Easy",
  "type": "mcq",
  "weight": 3,
  "description": "## Choosing the Minimal Permission\n\nA private SSH key file should be readable and writable by its owner only — nobody else should be able to read, write, or execute it. Which `chmod` octal value is correct?",
  "options": [
    { "id": "a", "text": "777" },
    { "id": "b", "text": "644" },
    { "id": "c", "text": "600" },
    { "id": "d", "text": "444" }
  ],
  "correct_option": "c",
  "explanation": "600 grants the owner read+write (4+2=6) and nothing at all to group or other (0, 0) — the minimum needed, and the actual permission SSH itself enforces for private key files. 644 incorrectly leaves the file readable by everyone; 777 grants full access to everyone, the opposite of least privilege.",
  "hints": [],
  "setup_commands": [],
  "default_namespace": "default",
  "teardown_commands": []
}