What is a port

A port is a potential communication channel, also an intrusion channel, open a port is a computer on the network opened a window, the hacker intrusion method is to use manual scanning or scanning software to find the server open to the port, according to its corresponding vulnerabilities to the server intrusion or attack, Therefore, the understanding of the port is very important.

There are probably three types of ports:

1: Recognized ports (well known ports): From 0-1023, they are bound to some services. Typically, the communication of these ports clearly indicates the protocol of some kind of service. For example, Port 21 is open to the FTP service.

2: Registration port (registrerd ports): From 1024-49151, they are loosely bound to some services that means there are many services bound to these ports, which are also used for many other purposes. For example, many systems handle dynamic ports starting at 1024.

3: Dynamic and/or Private ports: from 49512-65535, these ports should not theoretically be assigned to the service. In fact, the computer typically allocates dynamic ports starting with 1024. Of course, there are exceptions, Sun's RPC port starts at 32768.