Windows Identy / Windows Principal

User identity is a common means of controlling access to a business application or limiting the options available within that application. The .NET Framework classes under the namespace System.Security.Principal are provided to assist in making such role-based security determinations.

*firstly you must add this dll :
System.Security.Principal;   System.Security.Policy;
then:
The Framework provides a WindowsIdentity class that represents an authenticated Windows user and a WindowsPrincipal class that encapsulates the WindowsIdentity and information about the user's role memberships. These objects representing the current user are accessible in one of two ways: using a static property on the Thread object or a static method on the WindowsIdentity object.
you can see example of windows identity and windows principal ;

namespace Example {     class Program     {         static void Main(string[] args)         {              WindowsIdentity kimlik = WindowsIdentity.GetCurrent();             Console.WriteLine(kimlik.Name.ToString());             Console.WriteLine(kimlik.Token.ToString());             Console.WriteLine(kimlik.AuthenticationType.ToString());             if (kimlik.IsAnonymous)                 Console.WriteLine("Genel kullanıcı");             if (kimlik.IsGuest)                 Console.WriteLine("Misafir kullancı");             kimlik = WindowsIdentity.GetCurrent();             WindowsPrincipal kimlik2 = new WindowsPrincipal(kimlik);             Console.WriteLine(WindowsBuiltInRole.Administrator);             kimlik2.IsInRole(WindowsBuiltInRole.Administrator);             Console.ReadLine();         }     } }

you will see like this when you run your code ….