Thursday, July 24, 2008

Login popup prompted to enter the credentials again and again when accessing FQDN through Windows Vista

Scenario:
Login popup is prompted recursively to enter the id pwd credentials again and again while opening a document located in the sharepoint area.

Reason:
This bug is nothing to do any thing with the 'Sharepoint'.
You will get prompted while accessing any office document.
By default, On a Windows Vista-based computer, you do not configure a proxy in Windows Internet Explorer and you use Web Distributed Authoring and Versioning (WebDav) to access a fully qualified domain names (FQDN) site.

In Windows Vista, Internet Explorer uses the Web Client service when you use Internet Explorer to access a WebDAV resource. The Web Client Service uses Windows HTTP Services (WinHTTP) to perform the network I/O to the remote host. WinHTTP sends user credentials only in response to requests that occur on a local intranet site.

WinHTTP does not check the security zone settings in Internet Explorer to determine whether a Web site is in a zone that lets credentials be sent automatically.If no proxy is configured, WinHTTP sends credentials only to local intranet sites.Note If the URL contains no period in the server’s name.

eg. the server is assumed to be on a local intranet site:
http://sharepoint/davshare.

If the URL contains periods, the server is assumed to be on the Internet. The periods indicate that you use an FQDN address. Therefore, no credentials are automatically sent to this server unless a proxy is configured and unless this server is indicated for proxy bypass.Note A server can be indicated for proxy bypass either through the bypass list or through the proxy configuration script.In this case, you are prompted to enter your credentials when the Web site asks for credentials. Even in this case, the security zone settings are ignored.

Fix:
  • Install Windows Vista Service Pack 1 or a later service pack.
  • Start -> Run -> regedit
  • Traverse to
    HKEY_LOCAL_MACHINE > SYSTEM > CurrentControlSet > Services > WebClient > Parameters
  • Right-click the 'Parameters' subkey, and choose New > Multi-String Value.
  • Type the name AuthForwardServerList.
  • Open the AuthForwardServerList value and type in the list of SharePoint server URL's that are trusted for your organization - one URL per line.
  • Start > Admin Tools> SERVICES -> Restart the WebClient service. Or reboot the PC.