Office documents prompt for login in anonymous SharePoint site

Question

I have a MOSS 07 site that is configured for anonymous access. There is a document library within this site that also has anonymous access enabled. When an anonymous user clicks on a PDF file in this library, he or she can read or download it with no problem. When a user clicks on an Office document, he or she is prompted with a login box. The user can cancel out of this box without entering a log in, and will be taken to the document.

This happens in IE but not FireFox.

I see some references to this question on the web but no clear solutions: http://www.microsoft.com/communities/newsgroups/en-us/default.aspx?dg=microsoft.public.sharepoint.windowsservices.development&tid=5452e093-a0d7-45c5-8ed0-96551e854cec&cat=en_US_CC8402B4-DC5E-652D-7DB2-0119AFB7C906&lang=en&cr=US&sloc=&p=1

http://www.sharepointu.com/forums/t/5779.aspx

http://www.eggheadcafe.com/software/aspnet/30817418/anonymous-users-getting-p.aspx

Answer 1

To disable login prompt opening office documents from SharePoint 2010 do the following settings in web.config

<system.webServer>
  <security>
    <requestFiltering allowDoubleEscaping="true">
      <!-- here's where the magic happens -->
      <verbs allowUnlisted="true">
        <add verb="OPTIONS" allowed="false" />
        <add verb="PROPFIND" allowed="false" />
      </verbs>
    </requestFiltering>
  </security>
</system.webServer>