TCP and UDP ports are unrelated. The TCP stack interprets TCP ports, while the UDP stack interprets UDP ports. Ports allow multiple devices to connect to a node by multiplexing the connection.
As a result, higher-level protocols may technically use the same or different TCP and UDP port numbers. One computer, on the other hand, can communicate with two different services at the same time using the same TCP and UDP port numbers.
Web servers, for example, bind to TCP port 80. To make it easier to remember, applications use the same port number for TCP and UDP. Although two applications connected to the same port number can perform the same function, TCP and UDP ports are not the same. They are independent of each other.
TCP/UDP Port Grouping
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Ports 0 – 1023:
This TCP/UDP port number is the most common and well-known port number. These ports are assigned to specific server services by the Internet Assigned Numbers Authority (IANA). For example, port 80 is used by a web server.
Ports 1024 – 49151:
These are ports that organizations, such as application developers, can register for use on certain services.
Ports 49152 to 65535:
The port number that can be used by client programs, such as web browsers. When you visit a website, your web browser will assign that session’s port number from within this range. As an application developer, you are free to use any of these ports.
Checking Applications Using TCP/UDP Ports in Windows 11
Windows 11 has provided a built-in utility to monitor port usage. Using this utility, you can monitor the process or application that is using the port in real-time.
- Open ” Resource Monitor “. Click the Start button on the Windows Taskbar, then in the search box type ” resource monitor “. And select the application in the search results.
- In the application window that opens, then click the “ Network ” tab. On the panel, click “ Listening Ports ” to expand.
From the picture, you can find out which application is using the port in the “Image” column and you can also get information from Address, Port, Protocol, and Firewall Status.