Validate a users credentials on the local machine


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:

<em><strong>FileNotFoundException unhandeled by user code. The network path was not found.</strong></em>

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?


Here's a way to logon the User (and thus check that it's a valid user/pass): <a href="http://msdn.microsoft.com/en-us/library/system.security.principal.windowsimpersonationcontext.aspx" rel="nofollow">MSDN Link</a>

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


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