Question

I have a Windows Service (running as the Local System user) that needs to validate a user based on username and password, in addition to checking if the user belongs to the group WSMA. My current code is like this:

var pc = new PrincipalContext(ContextType.Machine);
using (pc)
{
  try
  {
    if (pc.ValidateCredentials(username, password))
    {
      using (var groupEntry = new DirectoryEntry("WinNT://./WSMA,group"))
      {
        foreach (object member in (IEnumerable)groupEntry.Invoke("Members"))
        {
          using (var memberEntry = new DirectoryEntry(member))
          {
            if (memberEntry.Path.ToLower().EndsWith(username.ToLower()))
            {
              return new LoginResult{ success = true };
            }
          }
        }
      }
    }
    return new LoginResult{ success = false };
  }
  catch (PrincipalOperationException poe)
  {
    if (poe.ErrorCode == -2147023688)
    {
      return new LoginResult { Success = false, ErrorMessage = "Password expired" };
    }
    throw poe;
  }
}

This all works as it should, as long as I’m connected to the network, but if I plug out my network cable, then the ValidateCredentials call give me the following error message:

FileNotFoundException unhandeled by user code. The network path was not found.

I guess this has something to do with AD, but I only need to check the local users, and not domain users so a network access should not be required.

Any way to do this using the PrincipalContext, or some other way that will work in a disconnected scenario?

Answer 1

Here’s a way to logon the User (and thus check that it’s a valid user/pass): MSDN Link

I guess this should work disconnected, too, if you use a local account