Pass Windows Auth to ASP .NET Core (Windows Service)

Hello:
This is how my "intranet" application works
1) JSON API developed using ASP .NET Core 1.1 and runs as a "Windows Service" - yes windows service.
2) The front end is a HTML5 application (angularJS) that makes calls to the Windows Service (running on port say 40001). The HTML5 application is hosted on IIS.
3) The ASP .NET Core service uses a static user name/pwd for SQL Server connection stored in the "appsettings.json".

Everything works well.
Now, instead of using a static username/pwd for the database connection, I would like to pass the Windows credentials from the IIS to the ASP .NET Core Windows Service.

Can you give me some pointers on how to get this accomplished. Basically, I would like the IIS to pass the credentials to my ASP .NET Core "Windows" Service..

Thanks!