Sometimes you want to know the username of a user that's logged on to your domain. This specially the occasion for intranet applications. Let's assume we are building an intranet application because this is the only occasion where a NTLM username is valid I guess. There is no way we can get the NTLM Username directly from within Silverlight yet. So we have two options left: Client Side Javascript and Server Side scripting.

Client Side

Let's begin with the Client Side Javascript. At least we should start investigating it. The first piece of code I found makes use of ActiveX, see the following:

var wshshell=new ActiveXObject("wscript.shell");
var username=wshshell.ExpandEnvironmentStrings("%username%");

Sadly it throws an error, not a good start. Google again. Not many options left, most people just say it isn't possible. After a while I found the following:

var wshNetwork = new ActiveXObject("WScript.Network");
var username = WshNetwork.UserName;

But this also throws an error. So I guess we are left to the Server Side solution.

Server Side

So what we have left is Server Side scripting. We can again take different approaches like calling the server side through Ajax but I took the easy way, by just generating the NTLM Username into the HTML. We can make use of the InitParams to pass some startup parameters to the Silverlight control. The InitParams is a string that has comma-separated name-value pairs that are separated by the equals sign. So this could look like the following in HTML:

<param name="InitParams" value="name1=value1,name2=value2" />

What we do in the ASPX page where the Silverlight control is hosted, add the following code in the Page_Load:

1 if (User != null && User.Identity != null && User.Identity.IsAuthenticated)
2   Silverlight1.InitParameters = string.Format("User.Identity.Name={0}", User.Identity.Name);

In Silverlight we can read this value in the App.xaml.cs.

1 private void Application_Startup(object sender, StartupEventArgs e)
2 {
3   string userName = e.InitParams["User.Identity.Name"];
4   this.RootVisual = new Page();
5 }

The generated HTML looks like the following:

<param name="InitParams" value="User.Identity.Name=DOMAINNAME\Username"></param>