skylark的总结

NAT的分类，比较早的有STUN(RFC3489)定义的四种类型： Full Cone: 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.

Determining NAT Mapping Behavior This will require at most three tests. In test I, the client performs the UDP connectivity test. The server will return its alternate address and port in