You are STUNning

A super simple multithreaded STUN server in Zig.

Always responds to a Binding Request with a Binding Success Response with an XOR-MAPPED-ADDRESS, which is sufficient for hole-punching in WebRTC, for example. Does not check for magic cookie to differentiate old (RFC 3489) clients.

Listens by default on UDP :: in dual-stack mode (IPv4 & IPv6) on default STUN port 3478 on all CPU cores.

STUN RFCs:

1. RFC 3489: First RFC, no XOR-MAPPED-ADDRESS. Only MAPPED-ADDRESS where some NATs rewrite unknown payloads.
2. RFC 5389: Defines XOR-MAPPED-ADDRESS.
3. RFC 8489: Current, adds more protocols and stuff.

Run

Linux

• Build: zig build-exe -fstrip -O ReleaseFast stun.zig
• Run: ./stun
• ./stun <host> <port> <threads>

Development

• Linux: zig run stun.zig
• Windows: zig run --library C .\stun.zig
  • Multithreading does not work on Windows.

Zig Version

Tested with 0.12.0-dev.3667+77abd3a96.