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Today, I would like to share with you the relevant knowledge about the concept of port in linux. The content is detailed and the logic is clear. I believe most people still know too much about this, so share this article for your reference. I hope you can get something after reading this article. Let's take a look at it.

In linux, the port is the outlet for the device to communicate with the outside world, which is often used to refer to the port in the "TCP/IP" protocol. According to the port number, the port can be divided into well-known port, registered port and dynamic port.

The operating environment of this tutorial: linux7.3 system, Dell G3 computer.

What is the meaning of port in linux

Definition of port:

The system program run by the computer is like a closed circle, and the system programmer cuts the circle into many segments, and these line interfaces are called ports (generally speaking, fracture, that is, interruptions). When the system runs to these ports, depending on whether the port is open or closed, if it is closed, the rope is connected, and the system runs down. if the port is open, the system gets the command. There is external data input, accept external data and execute.

Classification of ports:

The port occupies two bytes, or 16 bits, in the header. Port numbers are used to represent and distinguish different applications in the network.

Ports are divided into three main categories:

(1) well-known port (Well Known Ports): the port number between 0 and 1023. These ports are managed by the IANA assignment. IANA assigns these ports to some of the most important applications so that all users know that when a new application appears, IANA must assign a recognized port to it.

Commonly known ports are:

FTP: 21

TELNET: 23

SMTP: 25

DNS: 53

TFTP: 69

HTTP: 80

SNMP: 161

(2) Registration port (Registered Ports): from 1024 to 49151. These are the port numbers that companies and other users register with the Internet Corporation for assigned names and numbers (ICANN). These ports are required for applications that communicate using the Internet's Transmission Control Protocol (TCP) and user Datagram Protocol (UDP). In most cases, these applications, like ordinary programs, can be opened by unprivileged users.

(3) Port number used by the client: 49152 / 65535. This type of port number is dynamically selected only when the client process is running, so it is also called a short port number. Is reserved for temporary use by the client process. It can also be understood that when the client starts, the operating system randomly allocates a port to communicate with the server, and the client process shuts down and reassigns a new port the next time it is opened.

A port is like a door, and the outside can communicate through different ports and processes of different services on the machine. The IP address and port number identify the only process that accesses the Internet host

These are all the contents of the article "what is the concept of Port in linux". Thank you for reading! I believe you will gain a lot after reading this article. The editor will update different knowledge for you every day. If you want to learn more knowledge, please pay attention to the industry information channel.

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