Wide area network server mode connection (p2s): an original new TCP / IP communication mode. It can realize the information transmission and monitoring of equipment Wan. Its advantages are as follows: 1. Avoid the trouble of port mapping for each extension in WAN connection. 2. Avoid the leakage of private information in the process of P2P transmission. 3. It contains DNS service protocol, which can be accessed to the server by IP address or directly connected by web address. Easy to operate.