spt-nat

NAT traversal library -- STUN, TURN, UPnP, NAT-PMP, hole punching, and relay management

Overview

spt-nat provides a comprehensive NAT traversal toolkit for establishing peer-to-peer connections across network address translators. It orchestrates multiple traversal strategies (STUN, TURN, UPnP, NAT-PMP, UDP hole punching) through a unified NatTraversalManager that automatically detects NAT type and selects the best strategy. This is the connectivity foundation for spt-p2p.

Key Features

• STUN client/server -- NAT type detection and external address discovery
• TURN client/server -- relay allocation for symmetric NAT fallback
• UPnP -- automatic port mapping via UPnP gateway discovery
• NAT-PMP -- port mapping via NAT-PMP/PCP protocol
• Hole punching -- coordinated UDP hole punching with configurable timeout
• Relay management -- connection relay with configurable pool limits

Dependencies

No internal SPT crate dependencies. Uses tokio for async I/O, dashmap for concurrent port mapping storage, and parking_lot for low-contention locks.

Usage

use spt_nat::{NatTraversalManager, NatTraversalConfig};

let config = NatTraversalConfig::default();
let manager = NatTraversalManager::new(config);
// manager.initialize().await?; // runs detection + gateway discovery

API Reference

Core Types

Type	Description
NatTraversalManager	Main orchestrator for all traversal strategies
NatTraversalConfig	Configuration for enabled strategies and timeouts
StunClient	STUN binding request client
StunServer	STUN server implementation
TurnClient	TURN relay allocation client
TurnServer	TURN server implementation
TurnAllocation	Active TURN relay allocation
UpnpManager	UPnP IGD port mapping manager
NatPmpClient	NAT-PMP/PCP client
HolePunchCoordinator	Coordinated UDP hole punching
RelayManager	Connection relay pool manager
NatInfo	Detected NAT type and external address
NatType	NAT classification enum
NatError	Crate error type