WCF reliable sessions via proxy server - not sending authentication credentials on Windows XP

Question

Hello,

I have a full trust XBAP which connects using reliable sessions to a remote service using the endpoint configuration attached below. The catch is that when running the application behind a client's organizational proxy server, the WCF requests are blocked on Windows XP but pass through fine on Windows 7. My suspicion (pending further analysis by the client) is that the default proxy credentials are not attached to the HTTP or HTTPS requests on the XP machines, despite the useDefaultWebProxy=true setting.

Is this a known issue on XP, or am I missing something? Is there a way to bypass this issue?

Thanks in advance for any help

Binding configuration for the secure (production) version:

<customBinding>
    <binding name="Https_IOltpLogic">
        <reliableSession ordered="False" inactivityTimeout="00:20:00" />
        <httpsTransport />
    </binding>
</customBinding>

For the demo (unsecured) version:

<wsHttpBinding>
    <binding name="WSHttpBinding_IOltpLogic"
         allowCookies="false"
         bypassProxyOnLocal="false"
         hostNameComparisonMode="StrongWildcard"
         messageEncoding="Text"
         textEncoding="utf-8"
         useDefaultWebProxy="true">
        <reliableSession enabled="True" ordered="False" inactivityTimeout="00:20:00" />
        <security mode="None" />
    </binding>
</wsHttpBinding>

(Please note that neither of them work under the described conditions!)

Answer 1

Well, it worked itself out after the client's network admin fiddled with the proxy server settings... since I wasn't allowed to analyze the HTTP traffic I don't really know which headers were missing/modified that caused the WCF requests to be blocked and the normal browser requests to pass though.