Fri 01 Nov 2019

How to locate and close an open port in Linux

So you're a network administrator and you have a number of Linux machines in your data center. You've found some odd traffic bouncing about your network and your curiosity is piqued. Is it possible that traffic is making use of an open port on a machine? If so, where's the port and how do you close it?

On those Linux machines, the task is actually pretty simple. I want to show you how to locate an open port and close it. I'll be demonstrating on Ubuntu Server 18.04, although the process will be similar on many distributions—the only difference being how you close the port.

Source: How to locate and close an open port in Linux, an article by Jack Wallen.

See also Use nmap to find machines and open ports and What's listening on port 8080.