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Lab 4#1207

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Dekart-hub wants to merge 3 commits into
inno-devops-labs:mainfrom
Dekart-hub:feature/lab4
Open

Lab 4#1207
Dekart-hub wants to merge 3 commits into
inno-devops-labs:mainfrom
Dekart-hub:feature/lab4

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Goal

Trace one POST /notes end-to-end with tcpdump/curl, debug a broken deploy outside-in, and decode the TLS handshake — done on macOS (the spec is Linux; adaptations are documented).

Changes

  • submissions/lab4.md — full write-up: Task 1 (annotated packet trace + 5 debug commands + 502 reflection), Task 2 (port-conflict reproduction, outside-in chain, blameless postmortem), Bonus (TLS 1.3 handshake decode), and a macOS↔Linux adaptation table.
  • submissions/lab4-trace.txt — the tcpdump -A capture of the traced request.

Testing

  • Packet capture: real TCP handshake → POST /notes201 Created → two-sided FIN, over the IPv6 ::1 loopback (lab4-trace.txt).
  • Broken deploy: listen tcp :8080: bind: address already in use reproduced; outside-in chain walked (lsof / curl / dig); repaired and re-verified (/health → 200).
  • Bonus: Caddy TLS proxy :8443 → :8080; openssl s_client -traceTLS 1.3 / TLS_AES_128_GCM_SHA256, self-signed cert chain decoded.
  • Note: a cross-fork PR doesn't run the fork's workflows; this lab is host-side tooling, not CI.

Checklist

  • Title is a clear sentence (≤ 70 chars)
  • Commits are signed (git log --show-signature)
  • submissions/lab4.md updated

…apture + Bonus pending

Signed-off-by: Aleksandr <55945487+Dekart-hub@users.noreply.github.com>
…rHello/cert chain via openssl -trace)

Signed-off-by: Aleksandr <55945487+Dekart-hub@users.noreply.github.com>
…ce.txt

Signed-off-by: Aleksandr <55945487+Dekart-hub@users.noreply.github.com>
@Dekart-hub Dekart-hub changed the title Lab 4: OS & Networking — trace, debug, and decode the substrate Lab 4 Jun 23, 2026
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