The first part is done using the MVC Authorize tag on the method
Now I need a way to also let user on our AD domain access. So the first thing I have done is created a custom authorization.. The code below shows what I am trying to do.. How do I do it? Or is it a simple addition to my config perhaps?
  public class AuthorizeUserAttribute : AuthorizeAttribute
{
    public string AccessLevel { get; set; }
    protected override bool AuthorizeCore(HttpContextBase httpContext)
    {
        var isAuthorized = base.AuthorizeCore(httpContext);
        //act as normal
        if (isAuthorized)
        {
            return true;
        }
        //check in AD member
        else
        {
            //Some code to check if the user who put the URL in the browser is a AD user on our domain???? 
            //return true
            //else
            return false;
        }
    }
}