The following sample shows how you can host a TCP server and HTTP server in the same ASP.NET Core application. The TCP server runs on port 8007 and the HTTP server runs on ports 5000 and 5001.
Under the covers, it's the same server (Kestrel) running different protocols on different ports. The ConnectionHandler is a new primitive introduced in ASP.NET Core 2.1 to support non-HTTP protocols. ConnectionHandlers are activated by the dependency injection system in ASP.NET Core; this means you can access any registered service in the constructor of your ConnectionHandler.
ConnectionHandlers also provide access to the connected client via a ConnectionContext. The ConnectionContext provides information about the underlying connection (like the connection id) and it also exposes the raw data stream using an IDuplexPipe. The IDuplexPipe is a new primitive that represents a bi-directional stream using the new System.IO.Pipelines library.
This is part of a larger effort called Bedrock. You can read more about it here.