Question

 Response.Write("Request.LogonUserIdentity.Name:" +Request.LogonUserIdentity.Name);
 Response.Write("<br/>");            
 Response.Write("WindowsIdentity.GetCurrent().Name:" + WindowsIdentity.GetCurrent().Name);
 Response.Write("<br/>");

as above, if I use anonymous credential, it will be:

Request.LogonUserIdentity.Name:NT AUTHORITY\IUSR

WindowsIdentity.GetCurrent().Name:IIS APPPOOL\TestSite

But after impersonator, LoginUserIdentity will be the same

Request.LogonUserIdentity.Name:NT AUTHORITY\IUSR

WindowsIdentity.GetCurrent().Name:impersonator identity

MSDN said that

The LogonUserIdentity property exposes the properties and methods of
the WindowsIdentity object for the currently connected user to
Microsoft Internet Information Services (IIS).

Why loginUserIdentity is always the identity anonymous used??

Answer 1

You misunderstand authentication and impersonation,

Property Value

Type: System.Security.Principal.WindowsIdentity
A WindowsIdentity object for the current Microsoft Internet Information Services (IIS) authentication settings.

Whether you enable impersonation or not, the logon user remains the same, so Request.LogonUserIdentity should remain the same, which obviously is correct and meet expectation.

The change of WindowsIdentity.GetCurrent is also expected, as that’s just caused by impersonation.

Reference:

http://msdn.microsoft.com/en-us/library/system.web.httprequest.logonuseridentity.aspx

http://msdn.microsoft.com/en-us/library/ms998351.aspx