---
title: "What is Listening on a TCP Port?"
description: "To find what is listening on a TCP/IP port, open a terminal and go to a shell command-line, and use lsof, a command that LiSts Open Files (TCP ports are considered a type of file in UNIX)."
source: https://www.pico.net/kb/what-is-listening-on-a-tcp-port/
markdown_url: https://www.pico.net/kb/what-is-listening-on-a-tcp-port.md
---

# What is Listening on a TCP Port?
To find what is listening on a TCP/IP port, open a terminal and go to a shell command-line, and use lsof, a command that LiSts Open Files (TCP ports are considered a type of file in UNIX). This checks all listening ports: The following check is specific to port 5432: These commands work for most Linux flavors.