C＃asp.net - 在部署服务器上获取Windows用户登录帐户

I am using C# asp.net to get windows login account (domain\username) for login my web automatically. I can get the account correctly when run the statement "System.Security.Principal.WindowsIdentity.GetCurrent().Name.ToString()" locally on visual studio. However, after deploying the web page to deploy server, it returns "NT AUTHORITY\IUSR".I am using C# asp.net to get windows login acco