ASP.NET web application -- how to get Windows user?

Question

My legacy ASP.NET Framework 4.5 (Windows auth) web site running in IIS uses the following code to get the Windows user id (to assess permissions):

String Name = System.Environment.UserName;

Looking at a log of this string, the Windows user ID isn't obtained correctly; rather, the name corresponding to the application pool credentials is obtained.

Is this due to using impersonation in web.config:

<identity impersonate="true" userName="app_user" password="xxxx" />

Or can I change a setting in IIS to correct this?

The web site used to work correctly. Something was changed in IIS and now it doesn't...

In web.config, windows authentication is specified:

<system.web>
<compilation debug="true" defaultLanguage="c#" targetFramework="4.5" />
<authentication mode="Windows" />. . .

You should never again set userName and password in identity tag. To configure an identity for the whole web application you should use application pool identity. To query the log on user information in your legacy ASP.NET web apps, use Page.User or Controller.User please. Don't know how you get started with this web app, but there are tons of samples over the internet telling the right way to go. — Lex Li
You might read my blog post for more details, blog.lextudio.com/… — Lex Li

Mikhail Mikhail · Accepted Answer · 2021-12-18T19:38:30

uses the following code to get the Windows user id (to assess permissions):

String Name = System.Environment.UserName;

If you already implemented the Windows auth within your ASP.NET app (actually, the following code is enough):

<configuration>
  <system.web>
    ...
    <authentication mode="Windows"></authentication>
  </system.web>
</configuration>

Retrieve the necessary info via the System.Web.HttpContext.Current.User / System.Web.HttpContext.Current.User.Identity.Name property value (wherever you are - ASPX Page Code Behind, ASP.NET MVC Controller, any ASP.NET app module):

Check out some related threads to understand the differences: System.Web.HttpContext.Current.User.Identity.Name Vs System.Environment.UserName in ASP.NET

ASPX Page Code Behind:

protected void Page_Load(object sender, EventArgs e) {
    //Page.User
    ...
}

ASP.NET MVC Controller:

public class HomeController : Controller {
    public ActionResult SomeActionMethod() {
        //User
    }
}

any ASP.NET app module:

public class X {
    public void Y() {
        //System.Web.HttpContext.Current.User
    }
}

ASP.NET web application -- how to get Windows user?

1 Answers