Disable Windows user's interactive login using C# service

Question

Is it possible to use a Windows service (C# - Local System priv.) to deny an interactive login?

What i want to achieve is when a user enters username and password, to be up to my service whether to allow him in or not.

Currently i do this by polling current interactive username every X seconds, and performing logout if needed. But i'd like to avoid this delay time because it allows user to login even for a few seconds. It would be more elegant to just deny logging in from the beginning.

Answer 1

As you're in a Windows Service, you can register yourself to handle the SERVICE_CONTROL_SESSIONCHANGE event. First, you must enable your service to handle this event :

public MyService()
{
    ...
    CanHandleSessionChangeEvent = true;
}

And then just override the OnSessionChange method :

protected override void OnSessionChange(SessionChangeDescription changeDescription)
{
    if (changeDescription.Reason == SessionChangeReason.SessionLogon)
    {
        // do work
    }
}

If you need more informations to do your work, I let you check the WTS API which will provide you dozens of informations (username is one of them) using the changeDescription.SessionId attribute (for example).