For laymen, you can simply understand ports as the exit for communication between a computer and the outside world. However, in network technology, ports generally have two meanings:
(1) Ports in Hardware Devices
Such as interfaces in switches and routers used to connect other devices. (SC ports, etc.)
(2) Ports in TCP/IP Protocols
Such as port 21 for FTP services, port 80 for web browsing services, etc.
Why are there two meanings? There is a reason for that.
As the internet became more popular, the interfaces in hardware alone could no longer meet the needs of network communication, which is why new technologies were introduced in the TCP/IP protocol, forming what we call “software ports,” allowing computers to connect and communicate across spatial limitations.
Theoretically, there can be a maximum of 65535 ports, so to facilitate understanding of ports, network ports are divided into three categories based on this number:
(1) Well-Known Ports
Ranging from 0 to 1023, these ports are often referred to as