Division of Network Port number

As we all know, at any time multiple processes may use either of the 3 transport layer Protocols of TCP,UDP,SCTP, these 3 protocols use a 16-bit integer port number to differentiate these processes.

When a customer wants to contact a server, it must identify the server that they want to communicate with. Tcp. UDP,SCTP defines a well-known set of port numbers to identify well-known services. Customers typically use ephemeral ports that are short lived, which are usually automatically assigned to customers by the Transport layer protocol. We usually don't care about the specific value of its ephemeral port, but just make sure that the port number is unique on the host.

Any TCP/IP implementation provides services that are port numbers between 1-1023, managed by the IANA distribution, where the port number below 255 is reserved for public applications, and the port number between 255-1023 is assigned to individual companies for special applications.

The common reserved TCP port numbers are:

HTTP, FTP 20/21,telnet 23,smtp 25,dns 53 and so on.

The commonly used reserved UDP port numbers are:

DNS 53,tftp 69,SNMP 161 and so on.

Each TCP header contains the source port number and destination port number to identify and differentiate the application process for the source-side device and destination-side device.

The port number can be divided into 3 categories:

1. It is well known that the port number is 0~1023. These port numbers are assigned and controlled by the IANA, they are bound to some services, and if possible, the same port number is assigned to the same given service as TCP,UDP and SCTP, for example, TCP or UDP port number 80 is given to the Web server.

2. The registered port number is 1024~49151. These port numbers are not controlled by the IANA, but are registered by the IANA and provide their list of usage to facilitate the entire population. If possible, the same port number is also assigned to TCP and UDP for the same given service. 49151 This limit is introduced to allow for a range of ephemeral ports.

3. Dynamic port or private port number 49152~65535.iana regardless of these ports, they are what we call the temporary port number.

Division of Network Port number