How to associate for every class in a system a port by composition in a class diagram?

Greetings to all UML experts.

I am working on creating a UML class diagram for a system I am currently working on. Within this context, I need to assign for every class of the system a single port. However, I am not sure how to represent this.

For example. Lets say I have a user class that access a service class with a service request class. And the service class outputs a service product class to a database class.

The user, service and database classes have to be assigned a port class by composition. What do i do in this case? Do I create one class called port and create a composition that connects with every other class or I create a port class associated again with composition for every different class (i.e. user, service, database)?

If then I have a system with 50 classes and each is composed of a port. Then in the class diagram I need to associate by composition all system classes with that single port?

Any help would be much appreciated.