1. In network technology, ports have two meanings: one is physical ports, such as interfaces used by ADSL modems, hubs, switches and routers to connect other network devices, such as RJ-45 ports and SC ports; The second is logical port, which generally refers to the port in TCP/IP protocol. Port numbers range from 0 to 65535, such as port 80 for browsing web services, port 2 1 for FTP services and so on.

2. Computer "port" is the literal translation of English port, which can be considered as the exit of computer communication with the outside world. Among them, the ports in the hardware field are also called interfaces, such as USB ports and serial ports. Ports in the software field generally refer to communication protocol ports in the network for connected services and connectionless services. They are abstract software structures, including some data structures and I/O buffers.

3. Connection-oriented service TCP protocol and connectionless service UDP protocol use 16bits port number to represent and distinguish different applications in the network, while network layer protocol IP uses specific protocol numbers (TCP 6, UDP 17) to represent and distinguish transport layer protocols.

4. The services provided by any TCP/IP implementation are port numbers between 1- 1023, which are allocated and managed by IANA. Among them, port numbers below 255 are reserved for public applications; Port numbers from 255 to 1023 are assigned to various companies for special applications; Port numbers higher than 1023 are called temporary port numbers, which are not specified by IANA.