I just installed the AD provider on our Intranet and was having a pretty big problem with accessing web services within the desktop modules directory that were not going through the authentication.   The DNN system kept redirecting to the Windowssignin.aspx page.   My fix was actually a quick code addition to the ActiveDirectory module to keep it from doing the redirect if the file extension was .asmx. 

The file in question is the AuthenticationModule.vb, Line 63.   I changed it from :

                If Request.Url.LocalPath.ToLower.EndsWith("install.aspx") OrElse Request.Url.LocalPath.ToLower.EndsWith("installwizard.aspx") Then
                    Exit Sub
                End If

To this :

                If Request.Url.LocalPath.ToLower.EndsWith("install.aspx") OrElse Request.Url.LocalPath.ToLower.EndsWith("installwizard.aspx") OrElse _
                             Request.Url.LocalPath.ToLower.EndsWith(".asmx") Then
                    Exit Sub
                End If

Hope that this will help someone keep from going through the same thing that I went through with trying to figure out a solution for this.   It would also be nice if there was an option in the next version of the AD provider that you can keep from redirecting with certain filetypes or even just certain files, and that you could set that via the settings.

Chaitanya Marvici

I ended up having to modify the code to Request.Url.LocalPath.ToLower.Contains(".asmx").  Please notice that I used "Contains" instead of "EndsWith". When using the ajaxcontroltoolkit autocompleteextender and what seems an authentication time out, the url being called was http:.../mywebservice.asmx/mywebmethod.  Obviously, the url was not ending in .asmx.  I would get an http response code of 302 which eventually somewhere down the line was changed to an http response code of 401 (unauthorized).  I spun my wheels a couple of days checking security on the .asmx file, the directory the file.