grceng.academy
YAML lab 40 bonus XP

Repair the upload evidence plan

Start labRead the room

Objectives

Halcyon's upload investigation has a draft claiming that link framing uses the TCP data allowance and that connection establishment proves record authorization. The lead asks you to turn it into a small, machine-checkable diagnostic plan, not to change production networking.

Use the fixture's explicit header assumptions. Complete the model mapping, PDU labels and payload budget, then select a source that records application authorization decisions and reject the handshake-only proof claim. Keep the YAML structure; all blank fields require values.

Upload path and control assertion

model: four-layer TCP/IP
path: client -> router -> service
ip_version: 4
ip_mtu_bytes: 1500
ipv4_header_bytes: 20
tcp_header_bytes: 20
options: none
tunnel: none
control: unauthorized record reads must be denied
available_sources:
  - application authorization logs (subject, resource, decision)
  - transport connection logs (ports, flags)
draft_claim: handshake success proves record authorization

Checks the server runs (6)

  • Map the routed layer between models
  • Distinguish all three protocol data units
  • Keep the IP MTU distinct from payload
  • Subtract the stated IP and TCP headers
  • Select evidence of the authorization decision
  • Limit the claim supported by a handshake

Check names are all you see here: the expectations that decide pass or fail, and the reference solution, stay on the server.

Step-by-step hints

The guided walkthrough, in full. It is free: no XP cost, and it does not touch the paid hint ladder or the reveal gate.

  1. Step 1

    Map the responsibility

    Locate routed addressing in each model and use the requested model's layer name, not the name from the other model.

    Map the routed layer between models

  2. Step 2

    Name nested units

    For each protocol, identify the unit it creates around the next protocol's content. Do not reuse one casual label for every nesting level.

    Distinguish all three protocol data units

  3. Step 3

    Separate budget from content

    Copy the size limit for the whole IP unit into the limit field. In the data allowance field, account for each stated header once and only once.

    Keep the IP MTU distinct from payloadSubtract the stated IP and TCP headers

  4. Step 4

    Test the assertion

    Choose the source whose recorded fields can establish a subject's access decision. Then decide whether connection establishment alone supports that same assertion; use a YAML boolean, not prose.

    Select evidence of the authorization decisionLimit the claim supported by a handshake

Rules summary

  • XP on pass

    40 bonus XP the first time every check goes green.

  • Paid hints

    2 available. Each costs 25% of the lab XP (about 10 XP).

  • Reveal solution

    Scores 0 XP and unlocks only after 3 check runs.

  • Attempt cap

    60 check runs per learner. The runner warns you in the last 10.

  • Drafts

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  • Walkthrough

    Always free and never penalised: use it before spending a hint.