Evidence at a glance
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What was done
This project provides a clean-room reverse-engineered specification and implementation of Unity's legacy RPC networking stack, including Python and TypeScript clients and servers, and tools for PCAP analysis.
The open-legacy-rpc project documents and implements the undocumented framing layer used by Unity's legacy RPC networking stack, which includes NetworkView, [RPC], and OnSerializeNetworkView components. The project is a clean-room reverse-engineering effort independent of Unity Technologies. It provides a Python reference implementation and a TypeScript production implementation, both supporting client and server functionality. The project also includes tools for decoding PCAP captures into structured JSON, allowing analysis of the protocol stack from RakNet through to game-specific data. Development and documentation were supported by Claude Opus 5.5 and Claude Sonnet 4.6. The project maintains active research plans for protocol verification and safety. While the Python package supports installation on versions 3.8+, only 3.11+ is tested in CI. Similarly, the TypeScript implementation requires Node.js 22+, with older versions being unsupported and untested. See the Unity Legacy Networking Wire Format for technical details.
Sources: Source 1
Reproduce it
Use the provided Python or TypeScript implementations. For traffic analysis, use the included PCAP decoder: python3 tools/decode_pcap.py capture.pcap.
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