Thank you very much! I think I understand it better now.

I think that a file authentication is sufficient for my uses. I only need the UsedID of the Log_on-Varible for some Database queries.

I checked the permissions and the Folder have read and read/execute permissions for the usergroup "everyone", so anybody should be able to load it (as it is in Intranet everyone is automatically logged on). I for myself have additionally write permission. IIS has also permission to modify. So for that part I should be able to view the pages, right?

The IIS is still configured to only Windows authentication (impersonation enabled, managed pipeline mode: integrated). But I can not view the page (still 404 Error page).

I tried some simple asp and aspx scripts and both worked and showed me the Uservariables i need. ( only the scripts on server, nothing else)

<% @ Page Language="C#" %>
<%
foreach (string var in Request.ServerVariables)
{
  Response.Write(var + " " + Request[var] + "<br>");
}
%>

After that, my Serveradmin turned on the Form Authentication again, so i can log on on dnn afterwards. Also she turned off the impersonation (i guess it was automatically turned off).

Now only the asp script is working and not the aspx scripts.

Now I put the dnn installation back on the server and try to run it, and still get the 404 error and no possibility to login.

Does this mean I can not access the files and something with the IIS is off? Or is it my configuration?

Im sorry, doing the third post in a row, but the whole day testing brought up some new results:

From Serverside I think everything is working fine. (impersonation is disabled by the serveradmin, Anonym, Basic and Windows Authentication enabled)

I wrote two Scripts: one .asp and one .aspx to read the servervariables.

When there is nothing but those scripts on the webspace the variables are empty --> as anonymuous Authentication is enabled

If I add a web.config file which restricts the Anonymous User from accessing then the Windows Authentication works....

        <authentication mode="Windows" />
        <authorization>
             <deny users = "?" /> <!-- This denies access to the Anonymous user -->
        </authorization>

... and the Servervariables will be populated in both scripts.

If I do a fresh install of DNN 7.1,switch Forms for Windows authentication in web.config add the two Scripts an run them, the asp-Script will return the User. The aspx-Script will return the empty String.

 <authentication mode="Windows"/>

If I now add the restriction of the anonymous User as above, the asp-Script still returns the User, but the aspx-Script will prompt me to insert User and Password.

So for me it seems like first the asp-File is not affected by the config-File. And second there is a Problem with the DNN web.config, as it works fine with the very small config file.

1) Do you know a reason why the DNN-web.config could cause such problems?

2) Is it possible to actually call the asp-Script from within a DNN-module to get the variable that way?What I think of is a small script that will read the servervariable and add it ad a response header. In c# i can then read that header.

Thank you for your help!