NatTypeTester/STUN/Enums/NatType.cs

namespace STUN.Enums
{
	/// <summary>
	/// https://tools.ietf.org/html/rfc3489#section-5
	/// https://tools.ietf.org/html/rfc3489#section-10.1
	/// </summary>
	public enum NatType
	{
		/// <summary>
		/// Unknown
		/// </summary>
		Unknown,

		/// <summary>
		/// Server is not unsupported for testing NAT type
		/// </summary>
		UnsupportedServer,

		/// <summary>
		/// UDP is always blocked.
		/// </summary>
		UdpBlocked,

		/// <summary>
		/// No NAT, public IP, no firewall.
		/// </summary>
		OpenInternet,

		/// <summary>
		/// No NAT, public IP, but symmetric UDP firewall.
		/// </summary>
		SymmetricUdpFirewall,

		/// <summary>
		/// A full cone NAT is one where all requests from the same internal IP address and port are 
		/// mapped to the same external IP address and port. Furthermore, any external host can send 
		/// a packet to the internal host, by sending a packet to the mapped external address.
		/// </summary>
		FullCone,

		/// <summary>
		/// A restricted cone NAT is one where all requests from the same internal IP address and 
		/// port are mapped to the same external IP address and port. Unlike a full cone NAT, an external
		/// host (with IP address X) can send a packet to the internal host only if the internal host 
		/// had previously sent a packet to IP address X.
		/// </summary>
		RestrictedCone,

		/// <summary>
		/// A port restricted cone NAT is like a restricted cone NAT, but the restriction 
		/// includes port numbers. Specifically, an external host can send a packet, with source IP
		/// address X and source port P, to the internal host only if the internal host had previously 
		/// sent a packet to IP address X and port P.
		/// </summary>
		PortRestrictedCone,

		/// <summary>
		/// A symmetric NAT is one where all requests from the same internal IP address and port, 
		/// to a specific destination IP address and port, are mapped to the same external IP address and
		/// port.  If the same host sends a packet with the same source address and port, but to 
		/// a different destination, a different mapping is used. Furthermore, only the external host that
		/// receives a packet can send a UDP packet back to the internal host.
		/// </summary>
		Symmetric
	}
}