competition-pcap-protocol

Reconstructs PCAP sessions and decodes application protocols to tie packet sequences to host behavior.

7|4|Updated Jun 22, 2026
One-click install
npx skills add https://github.com/dbx0/skills --skill competition-pcap-protocol-dbx0
Or copy as Structured Prompt for Agent
Please help me install this Agent Skill.
Skill: competition-pcap-protocol
Source: https://github.com/dbx0/skills/tree/main/skills/forensics-dfir/collection/competition-pcap-protocol
Command: npx skills add https://github.com/dbx0/skills --skill competition-pcap-protocol-dbx0

SYSTEM DOCUMENTATION & REQUIREMENTS

💡 This Skill includes references (resource) components.

What problem does it solve? Analyzing packet captures in CTF and forensic scenarios often stalls when analysts reason from isolated packets instead of reconstructed sessions, missing the decoded content and behavioral links that prove the challenge path. ## Core Features & Use Cases - Session Mapping: Groups traffic into sessions by endpoints, ports, TLS handshakes, DNS lookups, and long-lived streams while flagging missing coverage, retransmits, and asymmetric routing. - Protocol Decoding: Reassembles TCP streams and UDP conversations, then recovers framing, message order, custom headers, compression, encryption boundaries, and transferred objects. - Behavior Correlation: Maps packet sequences to host events, malware branches, login flows, uploads, exfiltration steps, or command channels. - Use Case: Given a CTF capture with a suspected custom C2 channel, rebuild the stream, decode the framing and commands, extract the transferred artifact, and prove which packet sequence triggered the host behavior. ## Quick Start Analyze this PCAP file by reconstructing its sessions, decoding the application protocol, and showing which packet sequence proves the challenge behavior.

Frequently Asked Questions about competition-pcap-protocol

High-intent search queries and answers about installing and using this skill.

FAQPage Schema
How do I analyze a PCAP file in a CTF challenge?

Start by establishing capture boundaries: hosts, time span, interfaces, missing packets, and stream count. Then group traffic into sessions before decoding payload semantics, and reassemble streams before interpreting individual fields.

How to reconstruct TCP streams from packet captures?

Reassemble the full TCP stream or UDP conversation before interpreting fields, recovering framing, message order, custom headers, and transfer boundaries. Keep payload direction, timing, and session state aligned with each decoded message.

Can this decode custom C2 or binary protocols?

Yes, the workflow covers custom headers, binary fields, compression, and encryption boundaries after stream reassembly. For deterministic replay of custom handshakes or checksums, it defers to the custom protocol replay skill.

Why does single-packet analysis fail in PCAP forensics?

Reasoning from isolated packets misses stream reassembly requirements, session state, and message ordering. Protocol recognition alone is insufficient without decoded content or a proven downstream behavioral effect.

When should I use timeline forensics instead of PCAP analysis?

Switch to host timeline forensics when the decoded session shows the problem is primarily a host-side sequence of events rather than packet order, protocol framing, or stream reconstruction.