Get current login user id from Active Directory in ASP.Net using C# and VB.Net

Use

string name = new System.Security.Principal.WindowsPrincipal(System.Security.Principal.WindowsIdentity.GetCurrent()).Identity.Name;

 or

string name = System.Environment.UserName

 or

string name = Environment.GetEnvironmentVariable("USERNAME");

 or

string name = System.Security.Principal.WindowsIdentity.GetCurrent().Name;