Find a Linux Process Listening on a Specific Port

This article shows how to find a process listening on a specific port in Linux.

Use the following command to find a process name listening on a specific port:

$ sudo lsof -i :8000

This example shows that the python3 process is listening on port 8000.

You can list the Linux processes that are listening on any TCP or UDP port:

$ sudo netstat -lntup| grep LISTEN

Here are the keys to use:

• -l – show listening ports only
• -n – display IP addresses and port numbers in numerical form and do not resolve them (check the /etc/services file to find the mappings between port numbers and service names)
• -t – show open TCP ports
• -u – show open UDP ports
• -p – show the ID of the process listening on the port

We have found the PID of the process using the port, and can now display detailed process information:

$ ps -aux | grep 72005

In this example, the process is started manually by the root user with the following command: python3 -m http.server (is used to run a simple HTTP server to share the current directory).

To kill the process listening on the busy port you want to free, run:

$ sudo kill -9 72005

You can check that the port is free now:

$ sudo lsof -i :8000