How to check which ports are open in Linux

Linux can check the opened ports through the following methods: 1. Use the netstat command "netstat -tuln", which will display all currently listening TCP and UDP ports; 2. Use the ss command "ss -tuln" " is used to display the currently listening TCP and UDP ports; 3. Use the lsof command "lsof -i" to display the currently open network connections and listening ports.

The operating system of this tutorial: Linux5.18.14 system, Dell G3 computer.

In Linux, you can use the following command to check which ports are open on the system:

1. Use the netstat command:

  netstat -tuln

The The command will display all currently listening TCP and UDP ports. Among them,
-t means to display the TCP port,
-u means to display the UDP port,
-l means to display only the listening port, and
-n means to display the port number in numerical form.

2. Use the ss command:

ss -tuln

This command is similar to netstat and is used to display the currently listening TCP and UDP ports. Among them,
-t means to display the TCP port,
-u means to display the UDP port,
-l means to display only the listening port, and
-n means to display the port number in numerical form.

3. Use the lsof command:

 lsof -i

This command will display the currently opened network connections and listening ports. Among them,
-i means only display network-related information.

These commands will list the listening ports on the system along with details of their status and associated processes. Note that executing these commands may require root or a user with appropriate permissions to view all port information.

Hope these commands are helpful to you! If you have any further questions, please feel free to ask.

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