asp.net core impersonate true

I´ve got a asp.net core application running on kestrel behind an IIS 7.5. I always use anonymous authentication configured in IIS to use one specific user from my active directory.

 I´m unable to get Access to the sql server because i cant Access with anonymous Access. It returns and error related to the session user when the program Access to the sql server:

SqlException: Error de inicio de sesión del usuario 'Domain\machine name$'.

This error means that he cant loging into the sql server.

Whith asp.net i get this configuring the web.config but in Core is my first time to configure this.

I have seen the same solution in different places that is not working for me:

In startup.cs i define a middleware to invoke impersonation:

public classImpersonate

        {

privatereadonlyRequestDelegate next;

public Impersonate(RequestDelegate next)

            {

this.next = next;

            }

publicasyncTask Invoke(HttpContext context)

            {

var winIdent = context.User.Identity asWindowsIdentity;

if (winIdent == null)

                {

await next.Invoke(context);

                }

else

                {

awaitWindowsIdentity.RunImpersonated(winIdent.AccessToken,async () => {await next.Invoke(context);

                    });

                }

            }

        }

Finally in Configure method i call to the middleware before i call to the mvc:

app.UseMiddleware<Impersonate>();

Aditionally in web.config i set

forwardWindowsAuthToken="true"

Any help?