What I mean is like servers on video games. You can run an application and it will set up a server on your computer with an IP and a port.

For example, how would you make an application where one host application sets up a thing where it has an IP and a port, and another computer that has access to the internet as well can type in the IP and port and it would be able to communicate with the host? I mean simple communication, like sending a boolean or String.

And would there be any security problems that would be needed to fix?