NatTypeTester is a STUN client library that detects the NAT type of a network connection.
The tool solves the problem of determining how a network's NAT (Network Address Translation) behaves, which is essential for peer-to-peer applications, VoIP, and other services that need to understand connectivity constraints. It implements the STUN protocol across multiple RFC standards to classify NAT behavior by testing how the network handles address mapping and packet filtering. The approach works by sending probe packets to a STUN server from different endpoints and analyzing the responses to determine the NAT's characteristics.
Developers building peer-to-peer applications, real-time communication systems, or any service requiring NAT traversal should consider this tool. It suits projects that need programmatic NAT detection rather than one-off testing. The project is distributed as a NuGet package for .NET environments, making it straightforward to integrate into C# applications. The tool supports both IPv4 and IPv6, and handles multiple transport protocols including UDP, TCP, TLS-over-TCP, and DTLS-over-UDP, providing flexibility for different network scenarios.
The project maintains active engagement with its codebase, regularly incorporating updates and refinements. Development activity shows consistent attention to code quality and feature completeness across the supported RFC implementations.
