


In the above picture, you can see all the open ports that are listening. On a Windows computer, you can run the command “netstat-an” to view what ports are open on the local computer. If the computer opens the outlook app to check email it would send a request to port 25, the server then knows to send that traffic to the mail server application. When the computer on the right makes a request to it will do so on port 443 this is how the server then knows to send that traffic to the web server application.

In the above example, the server on the left is running two applications: a web server on port 443 and a mail server on port 25. The port will identify specific applications in use on the remote system. When you use your phone, laptop, server, or anything that is connected to a network it makes connections to other networked devices on a port. What is a Port?Ī computer networking port is simply a communication channel that allows networked devices to connect and send data to each other. I also walk through a real-world example of running a port scan on a large network to find an insecure FTP server. In this tutorial, you will learn the basics of port scanning, what are ports, the most popular ports, and the different Nmap port scanning techniques.
