Anonyms user download Excel file without prompt for password

Last week I had a problem, that I have met a few times before. The problem is when an user clicks on an Excel file and open the file. Then the user gets a login box. Although that anonymous access is enabled. I also tested to give anonyms users full control but no luck. The solution is to change the web.config for the web application and remove the "verse" options and plug locate the system.webServer /security/requestFiltering

The web.config before:

1 <system.webServer>
2     <security>
3         <requestFiltering allowDoubleEscaping="true">
4             <requestLimits maxAllowedContentLength="2147483647" />
5         </requestFiltering>
6     </security>

The web.config after:

 1 <system.webServer>
 2     <security>
 3         <requestFiltering allowDoubleEscaping="true">
 4             <requestLimits maxAllowedContentLength="2147483647" />
 5                 <verbs allowUnlisted="true">
 6                     <add verb="OPTIONS" allowed="false" />
 7                     <add verb="PROPFIND" allowed="false" />
 8             </verbs>
 9         </requestFiltering>
10     </security>