Question

I’m currently developing an application that needs to communicate with a webservice on the internet. Internet explorer is until know the only application that is connecting to the internet through a proxy server.

The proxy settings are setup to “Use automatic configuration script”.

I have kept the default setting

<binding useDefaultWebProxy="true" />

And additionally set

<security mode="TransportCredentialOnly">
        <transport clientCredentialType="Windows" proxyCredentialType="Basic"
          realm="" />
        <message clientCredentialType="UserName" algorithmSuite="Default" />
</security>

But no luck. I keep getting “(407) Proxy Authentication Required.”

I have done some Google-ing, but the solutions do not seem to fit my situation.

Short update:
The application should run with the default user credentials, and use those credentials
through NTLM to authenticate with the proxy. But even when I set the client to do that it doesn’t seem to help.

Answer 1

Keep the <binding useDefaultWebProxy="true" /> setting, and make sure useDefaultCredentials is set to true in your app.config file (this setting is false by default):

<system.net>
    <defaultProxy useDefaultCredentials="true"/>
</system.net>

For more information, see my blog post “Using HTTP Proxy Servers“.