Question

I have a C# application that will use corporate Active Directory for authentication for half the users and a custom authentication method for the other half.

I already managed to authenticate users in AD using DirectoryEntry, DirectorySearcher, etc. and also have my custom authentication working.

However, I want to know if a user has already been logged in his computer using the corporate domain, then that user won’t be shown any Logon form and has to pass to the application.

I know I can use WindowsIdentity.GetCurrent().IsAuthenticated, but that returns “true” for both the locally logged users and the Domain logged users.

I want to know how can I tell apart the first from the latest.

(Note: this is a desktop application)

Answer 1

I also maintain a winforms desktop application that uses active-directory for in office users and supports non-office users as well.

This may be more then your asking for but since I have the same scenario as you I’m going to offer it anyway because it came together in a kind of a nice way, where I really didn’t write too much code and has been working well.

I’m sure others might have done this with a package as opposed to rolling their own – and to be honest I will probably go that route the next time I have this requirement…

Here it is:

Conceptually I took a cue from ASP.NET and broke security into two logical pieces:

Authentication – Who is this user?

Authorization – Can the user do this?

My implementation uses a simple database:

Here’s a snippett from the main form of my application:

    public EOMForm()
    {
        InitializeComponent();

        // Show the connection string when hovering over the database label (Test Mode Only)
        if(Properties.Settings.Default.TestMode)
            this.toolTip1.SetToolTip(this.databaseLabel, EomAppCommon.EomAppSettings.ConnStr);

        // Security
        DisableMenus();
    }

    private void DisableMenus()
    {
        // Disable individual menu items
        foreach (var menuItem in this.TaggedToolStripMenuItems())
            menuItem.Enabled = Security.User.Current.CanDoMenuItem((string)menuItem.Tag);

        // Apply disabled color to top level menus that have all their items disabled
        foreach (var menu in menuStrip1.DisabledMenus())
            menu.ForeColor = SystemColors.GrayText;
    }

And here’s the supporting utility code.

Finally, I administer it with with an ASP.NET scaffold site: