Authenticating another user when using Windows Authentication

Question

I have a .NET MVC 4 application that uses Windows authentication. Some users are administrators, and need to be able to enter data on behalf of other users.

I have a text box where the admin enters the name of another user. How can I check to verify that the text entered is an existing Windows username?

Answer 1

You could use the FindByIdentity method:

string username = "Some username you retrieved from the TextBox";

using (var ctx = new PrincipalContext(ContextType.Domain, "YOUR_DOMAIN"))
using (var user = UserPrincipal.FindByIdentity(ctx, IdentityType.SamAccountName, username))
{
    bool userExists = user != null;
    // here you know whether the user exists or not
}