style="font-size: 9pt; color: green; font-family: tahoma">client b之间就可以直接通信，而无需s来牵线搭桥了。(这就是所谓的打洞技术)！
the udp hole punching technique has several useful properties. once a direct peer-to-peer udp connection has been established between two clients behind middleboxes, either party on that connection can in turn take over the role of "introducer" and help the other party establish peer-to-peer connections with additional peers, minimizing the load on the initial introduction server s. the application does not need to attempt to detect explicitly what kind of middlebox it is behind, if any [stun], since the procedure above will establish peer- to-peer communication channels equally well if either or both clients do not happen to be behind a middlebox.? the hole punching technique even works automatically with multiple nats, where one or both clients are removed from the public internet via two or more levels of address translation.
