Check Open Ports on Linux Before It’s Too Late (ss command)
In this short tutorial, **Check Open Ports on Linux Before It’s Too Late (ss command)**, you’ll learn how to **quickly list open ports, identify listening services, and see which processes are using them with `ss -tulnp`**.
We’ll break down the command, explain the output, and show how to check if a port is in use, find the process behind it, and troubleshoot common issues like “port already in use.” This works on Ubuntu, CentOS, and most Linux distributions using the command line.
You’ll also see how this compares to older tools like netstat, and how to safely inspect TCP and UDP listening ports for basic security awareness and system troubleshooting.
Topics covered:
How to check open ports in Linux (command line)
Linux list open ports with process
Check if a port is in use or blocked by firewall
TCP and UDP listening ports explained
Netstat alternative using `ss`
Perfect for beginners in Linux, networking, and anyone who wants to understand what’s running on their system.
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