ced4568andClaude Sonnet 5
e007bcf000
Adds all 6 ROOT 02 modules (Linux system administration, storage & filesystems, the Networking Mental Model, Linux network inspection, DNS & HTTP, Linux troubleshooting) — 37 activities, each with a real lesson, demonstration/guided exercise, knowledge check, hands-on Lab, and reflection. The Networking Mental Model module (M3) gets deliberately extra depth per its "critical module" designation, with no lab by design — conceptual mastery via knowledge check and guided exercise, matching root-05-m00's own precedent. Adds 6 new hands-on Linux/networking scenarios plus 2 MCQs: linux-service-inspection (inspects the platform's own real nginx without touching it — a genuinely safe, real service-inspection target that avoids ever risking the Lab's own connectivity), linux-service-lifecycle (start/ verify/stop a fully controllable service), linux-storage-inspection, linux-network-inspection (ip/ss/getent/curl, each framed as answering one specific diagnostic question), linux-dns-http-diagnosis (a genuine DNS-resolves-but-wrong-port failure, diagnosed and fixed), and linux-troubleshooting-framework (a real missing-config-file failure, resolved via the RootNode Observe/Evidence/Hypothesis/Test/Repair/Validate/Prevent framework). All tested end-to-end via the real scenario-validation API, including negative tests confirming they fail when unsolved. Wires rootnode-linux-networking-assessment (2 required + 4 random-draw scenarios) using the existing Phase 3B assessment engine. Co-Authored-By: Claude Sonnet 5 <[email protected]>
43 lines
2.9 KiB
JSON
43 lines
2.9 KiB
JSON
{
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"id": "linux-dns-http-diagnosis",
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"title": "DNS Resolves, But the Connection Still Fails — Why?",
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"category": "Networking",
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"isolation_type": "shared_namespace",
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"difficulty": "Medium",
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"type": "task",
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"weight": 6,
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"description": "## DNS Resolves, But the Connection Still Fails — Why?\n\nAn application is supposed to be reachable at `http://broken-app.test:9091/`. A teammate insists \"DNS must be broken.\" Prove or disprove that, then actually fix the problem.\n\n**Your task:**\n\n1. Confirm whether `broken-app.test` actually resolves (`getent hosts broken-app.test`) — record your finding\n2. Try `curl http://broken-app.test:9091/` and observe what actually happens\n3. Find out what's REALLY running and on which port (hint: something already answers on a different port)\n4. Fix it so `curl http://broken-app.test:9091/` succeeds with a 200 response\n\nDo not just change the app's advertised port in documentation — make the SERVICE actually listen on 9091.",
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"hints": [
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{
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"title": "Separate DNS from connectivity",
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"body": "`getent hosts broken-app.test` only tells you whether the NAME resolves — it says nothing about whether anything is listening on the port you're trying to reach. Test them as two separate questions.",
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"command": "getent hosts broken-app.test"
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},
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{
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"title": "Finding what's actually running",
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"body": "`ss -lnt` lists every port something is actually listening on right now — compare that against 9091.",
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"command": "ss -lnt"
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},
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{
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"title": "The fix",
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"body": "Stop whatever's running on the wrong port, then start the real service correctly on 9091.",
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"command": "kill $(cat /srv/dns-http-lab/wrong.pid)\npython3 -m http.server 9091 --directory /srv/dns-http-lab &\necho $! > /srv/dns-http-lab/fixed.pid"
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}
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],
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"setup_commands": [
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{ "command": "mkdir -p /srv/dns-http-lab && echo 'app running' > /srv/dns-http-lab/index.html" },
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{ "command": "grep -q broken-app.test /etc/hosts || echo '127.0.0.1 broken-app.test' >> /etc/hosts" },
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{ "command": "python3 -m http.server 9095 --directory /srv/dns-http-lab >/srv/dns-http-lab/wrong.log 2>&1 & echo $! > /srv/dns-http-lab/wrong.pid" }
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],
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"validation": {
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"commands": [
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{ "description": "broken-app.test genuinely resolves (DNS was never the actual problem)", "command": "getent hosts broken-app.test | awk '{print $1}'", "expected_output": "127.0.0.1", "match": "exact" },
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{ "description": "the service now actually answers on port 9091", "command": "curl -sf http://broken-app.test:9091/ -o /dev/null -w '%{http_code}'", "expected_output": "200", "match": "exact" }
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]
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},
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"default_namespace": "default",
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"teardown_commands": [
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{ "command": "[ -f /srv/dns-http-lab/wrong.pid ] && kill $(cat /srv/dns-http-lab/wrong.pid) 2>/dev/null; [ -f /srv/dns-http-lab/fixed.pid ] && kill $(cat /srv/dns-http-lab/fixed.pid) 2>/dev/null; rm -rf /srv/dns-http-lab" }
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]
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}
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