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This article mainly introduces the relevant knowledge of "how to query the port in linux". The editor shows you the operation process through an actual case. The operation method is simple and fast, and it is practical. I hope this article "how to query the port in linux" can help you solve the problem.

Linux query port method: 1, use the netstat command, syntax "netstat [- acCeFghilMnNoprstuvVwx] [- A] [--ip]"; 2, use the ss command to display detailed TCP and connection status information; 3, use the lsof command.

The operating environment of this tutorial: linux5.9.8 system, Dell G3 computer.

Linux query port

Use netstat to check the port

Netstat is a command line tool that provides information about network connections.

To display all open ports, use the following command: netstat-anp

To list all TCP or UDP ports that are listening, including services that use port and socket status, use the following command: netstat-tunlp

The options used in this command have the following meanings:

-t-displays the TCP port. -u-displays the UDP port. -n-displays a numeric address instead of a hostname. -l-only the listening port is displayed. -p-displays the PID and name of the process. This information appears only if you run the command as root or sudo.

Query the specified port and filter through grep: netstat-tnlp | grep: 80

Show an example:

Note: Proto-the protocol used by the socket. Local Address-the IP address and port number on which the process listens. PID/Program name-PID and process name.

Use ss to check the port

Ss is the new netstat, with roughly the same command options. It lacks some netstat functionality, but exposes more TCP status, and is slightly faster.

Use example: ss-tunlp

Use lsof to check the port

Lsof is a powerful command-line utility that provides information about files opened by a process.

In Linux, everything is a file, and sockets can be thought of as files written to the network.

To use lsof to get a list of all listening TCP ports: lsof-nP-iTCP-sTCP:LISTEN

The options used are as follows:-n-do not convert the port number to the port name. -p-do not resolve the hostname, display the numeric address. -iTCP-sTCP:LISTEN-displays only network files with the TCP protocol status of LISTEN.

Examples of use:

To find a process that is listening on a specific port, such as 3306, use the following command: sudo lsof-nP-iTCP:3306-sTCP:LISTEN

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