competition-pcap-protocol

A CTF workflow for reconstructing network conversations from packet-capture files. A packet capture, or PCAP, records network traffic for later analysis.

In plain words
What is it for?
Use it to analyze TCP or UDP sessions, application protocols, HTTP traffic, DNS, WebSockets, beacon timing, and packet-to-process evidence.
Why use it?
It turns individual packets into complete sessions and transferred data, making protocol behavior and timing easier to prove.

Skill for Claude CodeCodex

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add skills/2233admin/reverse-skill-evolver/competition-pcap-protocol
Any agent
npx skills add 2233admin/reverse-skill-evolver --skill competition-pcap-protocol
Clone the repo
git clone --depth 1 https://github.com/2233admin/reverse-skill-evolver

Made for: Claude Code, Codex.

Per session 117 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 689 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin 100% copy Near-identical to another mod in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5 $0.00117 $0.00689
Opus 5 $0.00059 $0.00345
Sonnet 5 $0.00023 $0.00138
Haiku 4.5 $0.00012 $0.00069

Measured 2d ago against content hash 18285bb445a8, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

competition-pcap-protocol scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 2d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

Origin

This is a copy

100% identical to competition-pcap-protocol — 0 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.

CTF-Sandbox-Orchestrator/competition-pcap-protocol/SKILL.md · 53 lines

How it starts

The opening of the file, as written. The whole thing — 53 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Competition PCAP Protocol

Use this skill only as a downstream specialization after $ctf-sandbox-orchestrator is already active and has established sandbox assumptions, node ownership, and evidence priorities. If that has not happened yet, return to $ctf-sandbox-orchestrator first.

Use this skill when the decisive evidence sits inside packet order, protocol framing, or stream reconstruction rather than a single IOC or host log.

Reply in Simplified Chinese unless the user explicitly requests English.

Quick Start

  1. Establish the capture boundaries first: hosts, time span, interfaces, missing packets, retransmits, and stream count.
  2. Group traffic into sessions before decoding payload semantics.
  3. Record protocol framing, sequence, timing, and transferred artifacts together instead of as isolated packets.
  4. Correlate packet evidence with host, malware, or app behavior only after the session is reconstructed.
  5. Reproduce the smallest decoded stream or transferred artifact that proves the challenge path.

Workflow

1. Build The Session Map

  • Identify endpoints, protocols, ports, TLS handshakes, DNS lookups, websocket upgrades, and long-lived streams.
  • Note missing capture coverage, asymmetric routing, packet loss, or reassembly issues before drawing conclusions.
  • Separate control channels, bulk transfers, keepalives, and noise.

2. Decode The Protocol Boundary

  • Reassemble TCP streams or UDP conversations before interpreting fields.
  • Recover framing, message order, custom headers, binary fields, compression, encryption boundaries, and object transfers.
  • Keep payload direction, timing, and session state aligned with each decoded message.

3. Tie Packets To Behavior

  • Show which packet sequence maps to which host event, malware branch, login flow, upload, exfiltration step, or command channel.
  • Distinguish protocol recognition from artifact recovery: naming HTTP, DNS, or a custom C2 is not enough without decoded content or proven downstream effect.
  • If the task becomes mostly a host timeline problem after decode, switch to the tighter forensic timeline skill.

Read the full file on GitHub · 53 lines

Files

What ships with it

2 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 2d ago First seen · 53 lines · 117 tokens per session scan A 18285bb445a8

Subscribe to this mod's changes

competition-pcap-protocol is a skill published in the GitHub repository 2233admin/reverse-skill-evolver (13 stars, last pushed 22d ago), licensed MIT. It adds 117 tokens to every session and 689 once invoked, about $0.0006 per session on Opus 5. A static security scan graded it A with 0 findings. It is 100% identical to competition-pcap-protocol, differing in 0 lines, and is treated as a copy.

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