Question

I have a .Net client WPF application using System.DirectoryServices and LDAP for authentication. On start of the app, I want to force users to re-authenticate using their domain account (which is how they logged into windows). I understand I can use the following to perform the authentication when a connection is available.

DirectoryEntry entry = new DirectoryEntry("LDAP://" + domain,
            userName, password);

The wrinkle is that the application is at times used by remote users who may not have a connection. Windows itself still allows domain users to sign on even when disconnected. Is there a similar means of authenticating users in a disconnected environment using the .Net Framework?

Answer 1

Believe I found a way to do this using the LogonUser function of advapi32.dll.

 Dim tokenHandle As New IntPtr(0)
 Const LOGON32_PROVIDER_DEFAULT As Integer = 0
 Const LOGON32_LOGON_INTERACTIVE As Integer = 2
 tokenHandle = IntPtr.Zero
 Dim returnValue As Boolean = LogonUser("<username>", "<domain>", "<password>", LOGON32_LOGON_INTERACTIVE, LOGON32_PROVIDER_DEFAULT, tokenHandle)

 Private Declare Auto Function LogonUser Lib "advapi32.dll" (ByVal lpszUsername As [String], _
                        ByVal lpszDomain As [String], ByVal lpszPassword As [String], _
                        ByVal dwLogonType As Integer, ByVal dwLogonProvider As Integer, _
                        ByRef phToken As IntPtr) As Boolean

When disconnected this appears to validate against the local cached version of the last log on.