How do I get the Windows Active Directory User ID inside a Blazor website?

Question

I have written a Blazor Server App and deployed it to IIS.

Inside the app I would like to access the database as the Windows Active Directory user using the site, not the IIS user.

This code works, but it always returns the IIS user:

System.Security.Principal.WindowsIdentity identity = 
    System.Security.Principal.WindowsIdentity.GetCurrent();

I have found and tried all the variants shown below, from my internet search, but none return the User ID from AD accessing the website. I am not an IIS admin - maybe the magic is in there? Appreciate any help.

// .name is always null
var httpUser = HttpContextAccessor.HttpContext.User.Identity;

// principal user is null
var principalUser = Thread.CurrentPrincipal; //.Identity.Name;

// Is this supposed to impersonate the AD User?
web.config
<system.web>
    <identity impersonate="true"/>
</system.web>

// This may only affect debugging??

• Project Properties
  • Debug/Launch Profiles
    • Disabled Anonymous Auth
    • Enabled Windows Auth

// Browsed through authState and see nothing resembling the AD User Id

var authState = await AuthenticationStateProvider
            .GetAuthenticationStateAsync();

Answer 1

The answer for me was to create a Blazor project and pick 'Authentication Type: Windows' during the project creation. (I had formerly left it defaulted to None since everyone already logged in to Windows I thought it would be redundant.) That resulted in the default Blazor app showing me the user's AD name (and not the IIS User name) in the upper right hand corner of index.

As a newcomer to asp.net I was probably asking for something that could never be accomplished with 'Authentication Type: None'. (As the first commenter suggested.)

Answer 2

Hope the following code helps.

private readonly AuthenticationStateProvider authStateProvider;

public async Task<string> GetADUserNameAsync()
{
    var authState = await authStateProvider.GetAuthenticationStateAsync();

    var userName = string.Empty;

if (authState != null)
{
    var user = authState.User;

       if (user.Identity.IsAuthenticated && user.Identity!= null && user!= null)
        {
        try
        {
            var adUserNameClaim = user.Claims.Where(x => x.Type == "preferred_username").First();

            if (adUserNameClaim != null)
            {
                var val = adUserNameClaim.Value;
                var mail = new MailAddress(val);
                userName = mail.User;
            }
        }
        catch(Exception ex) {}
    }
}

  return userName;
}