01
The problem
An HTTP proxy does not cover every desktop protocol. I needed a way to inspect and intercept raw TCP traffic in Burp Suite, without treating each captured chunk as a complete application message.
Open-source tool · Rust + Java
Burp-TCP
A Rust TCP relay and Java extension that bring desktop traffic into Burp Suite for inspection and manual testing.
RustJava 21SOCKS5ProtobufBurp Montoya API
Open-source tool
Tool overview
The problem
How do I inspect desktop traffic outside an HTTP proxy?
Approach
I routed TCP connections through a Rust SOCKS5 relay, with controls provided by a Java extension in Burp Suite.
Result
Inspect captured bytes, pause traffic in either direction, and resend data from Burp Suite. Source code and automated tests are available on GitHub.
Source code / Built with Rust and Java
Architecture
The relay carries application traffic; the Burp extension controls capture and interception.
- 01Desktop application
- 02Rust SOCKS5 relay
- 03TCP target
Java Burp extension · WebSocket + Protobuf
02
How it works
An asynchronous Rust SOCKS5 relay captures traffic in both directions. The Java extension adds interception controls, traffic history and a repeater that sends data once each time you trigger it, all inside Burp Suite.
Implementation
Features
- 01SOCKS5 CONNECT relay bound only to loopback
- 02TCP capture in both directions, with timestamps and offsets
- 03Optional manual interception in either direction
- 04Traffic history, hex and text views, and a repeater
- 05WebSocket and Protobuf for communication between components
- 06Windows CI builds and automated tests
Scope
Limitations
- Does not decrypt TLS
- Does not support UDP
- Captures TCP chunks; does not reassemble complete protocol messages
- Holding a stream can cause application heartbeat timeouts