What are Ports in Networking?

Many are the times that we have heard about ports in networking. And when we have problems in our program, many times we realize that there is a problem with the port, either because it is not closed, or because it is not the correct one, etc. But what is a port really and what are they used for?

Briefly, we could say that a port is a virtual point where network connections start and end. Each port is associated with a specific process or service and they are software-based, as they are managed by a computer's operating system. 

A network protocol is an established set of rules that determine how data is transmitted between different devices in the same network. Essentially, it allows connected devices to communicate with each other, regardless of any differences in their internal processes, structure or design.

A port is a number used to uniquely identify a transaction over a network by specifying both the host and the service. They are necessary to differentiate between many different IP services, such as web service (HTTP), mail service (SMTP), and file transfer (FTP).

Now, in order to better understand the idea of what a port is in networking, let's make an example. Imagine that you are at the airport in Barcelona (Spain), and you have a meeting in Canada, so you have to go there. You will know what plane you have to take, right? What if you take a plane to Pekin (China)? What would happen, would be that you would not be able to have the meeting in Canada because obviously, you would not be there. Is it true? Somehow, this is how the ports work. since if you want to use a specific service, you have to go through a specific port.

In the table below, you can see the most commonly used ports in networking. Also, we have selected the most used ports in Industrial Shields as Node-RED port, MQTT port, Modbus TCP port, etc.

So, when a program on your computer sends or receives data over the Internet it sends that data to an IP address and a specific port on the remote computer. Also, it receives the data on a usually random port on its own computer.

Therefore, if it uses the SSH protocol to send and receive the data then it will connect and bind itself to a SSH port. The same will happen with the rest of the protocols and ports.

Finally, we hope to have helped you out with a better understanding of ports and how they work!