---
title: Protocol Reverse Engineering
category: product
entity_type: skill
price: $15
canonical: https://forgehouse.ai/skills/protocol-reverse-engineering/
lang: en
hreflang_alt: https://forgehouse.ai/tr/skiller/protocol-reverse-engineering/
last_updated: 2026-06-20
---

# Protocol Reverse Engineering

> Master network protocol reverse engineering including packet analysis, protocol dissection…

A complete methodology for capturing, dissecting, and documenting unknown or proprietary network protocols, from raw packet capture all the way to a publishable specification. It walks Claude through traffic capture (Wireshark, tcpdump, mitmproxy), binary structure decoding, encryption detection, and active validation, turning opaque byte streams into mapped, parseable message formats. The result is interoperability, security research, and debugging power over communication you don't have docs for.

## Use cases
- Reverse engineer a proprietary binary protocol
- Capture and analyze unknown network traffic
- Decode TLV and length-prefixed message formats
- Detect whether a payload is encrypted vs plaintext
- Write a Wireshark Lua dissector for a custom protocol
- Document a protocol spec for interoperability

## Benefits
- Turn unlabeled byte dumps into a documented, parseable message format
- Identify encryption layers fast using entropy thresholds before wasting time
- Isolate target packets from millions using layered display-filter chains
- Ship a validated parser and spec a teammate can build against

## What’s included
- Capture recipes for Wireshark, tshark, tcpdump, and mitmproxy (incl. ring-buffer and MITM)
- Python parsers for fixed-header, length-prefixed, and nested TLV structures with struct.unpack
- Entropy classifier (plaintext <6.0 / compressed 6.0-7.5 / encrypted >7.5) and hex-dump formatter
- TLS analysis: JA3/JA3S fingerprinting, certificate extraction, pre-master-secret decryption
- Ready-to-edit Wireshark Lua dissector and a protocol specification template
- Active testing with Boofuzz fuzzing and Scapy replay/modification

## Who it’s for
Security researchers, network engineers, and developers who need to understand, document, or debug protocols that have no public specification.

## How it runs
What is that device actually saying on the wire? From entropy checks to a working Wireshark dissector, an unknown protocol goes from raw capture to documented specification, then gets attacked at the edges.
1. Capture traffic across multiple sessions and scenarios with tshark/tcpdump (mitmproxy when TLS interception is needed), using ring buffer capture so long sessions are never lost.
2. Isolate the target with chained Wireshark display filters, then run a Shannon entropy check on payloads: below 6.0 means parse directly, above 7.5 means encryption, so the path switches to key recovery (SSLKEYLOGFILE decryption, JA3 fingerprinting) before any parsing.
3. Map message boundaries and structure across samples: magic number, version, type and length fields, then test the hypothesis with struct.unpack and TLV decomposition instead of guessing.
4. Draw the protocol state machine (INIT, HELLO, WAIT_ACK, CONNECTED, CLOSE) by following streams; transitions that should be impossible reveal either bugs or exploit paths.
5. Document the format as a real specification, header offset tables, message type catalog, state diagram, and write a Lua dissector so Wireshark decodes the protocol natively from then on.
6. Validate the understanding by building a parser/generator, then attack the edges: boofuzz fuzzing of every field and Scapy replay plus modified-replay tests against sequence and anti-replay handling.

## FAQ
### The traffic I need to analyze is TLS-encrypted, is that a dead end?
Not necessarily. The TLS analysis section covers JA3/JA3S fingerprinting, certificate extraction, and pre-master-secret decryption when you control an endpoint, and mitmproxy capture recipes handle the MITM case. Fully opaque third-party encryption you cannot key into stays opaque.

### How does it tell encrypted payloads from compressed or plaintext ones?
An entropy classifier scores the bytes: below 6.0 reads as plaintext, 6.0 to 7.5 as compressed, above 7.5 as likely encrypted. That check runs early so you do not waste hours trying to parse ciphertext as a message format.

### Will it reverse engineer a binary executable to extract the protocol logic?
No. The methodology works from the wire: packet capture, binary structure decoding with struct.unpack, active testing with Scapy replay and Boofuzz fuzzing. Disassembling the client binary itself is a different discipline outside this scope.

## Price
$15, one-time, no subscription. VAT included.

Related guide: [AI for application security](https://forgehouse.ai/guides/ai-application-security/)