What is a port? Easily explained
When it comes to Internet connections, the term port is used again and again. But what is that exactly? Translated, the term stands for "port", connection or "opening". In this article we explain how to understand the whole thing in relation to the computer and the Internet.
Port - what is it actually?
The English word "port" can also be translated with the word "gate" or "passage". A port allows communication between your computer and other computers as well as the Internet. A firewall closes unused ports so that no viruses can get to your PC through them.
- With ports, data packets can always be assigned to a suitable application on the Internet. Your computer has a total of 65, 536 ports. If a data packet, for example an e-mail, arrives on your computer, it is always routed via the port reserved for e-mails.
- For example, if you open the website CHIP.de, your computer sends a request to the web server for the required data. This request is sent via port 80, which is always used for websites.
- Pictured, it becomes a little easier. Computers send data in small packages. The port is written to the packet as the recipient. The package will then be let through the door with the correct number and sent.
- The protocols TCP and UDP have surely already run into you. This enables, among other things, direct connections between two applications on two computers. This is an advantage for direct file sharing, for example.
The individual ports are required for this
- The possible port numbers range from 1 to 65535. The first 1-1023 ports were determined by the Internet Assigned Numbers Authority (IANA) for certain services and purposes. So port 80 is used for surfing (HTTP) and port 25 is always used for emailing (SMTP).
- The ports between 1024 and 49151 can be freely assigned by programs and applications. Similar to a website, a company can buy a port for its service so that the data packets are guaranteed to arrive at their destination.
- The remaining ports between 49152 and 65535 are dynamic. This means that these ports are not directly assigned to any application. These, as well as all ports over 1023, are considered a potential security risk since malware can get to your computer via the ports. The firewall tries to prevent this as much as possible.
In the next practical tip, we will explain what the terms TCP and IP address are all about.