说明：  ser Datagram Protocol,简称UDP)是基于无连接的通信协议，不保证可靠数据的传输；"传输控制协议"（Transmission Cotrol Protocol，简称TCP）是基于连接的通信协议，可提供个两台计算机之间可靠无差错的数据传输。但是UDP能够向若干台目标计算机发送数据；接收发自若干个源计算机的数据。而在
(Ser datagram protocol (UDP) is based on connectionless communication protocol, which does not guarantee reliable data transmission; transmission control protocol (TCP) is based on connection, which can provide reliable and error free data transmission between two computers. But UDP can send data to several target computers and receive data from several source computers. While in)