How to authenticate against a proxy when using the HttpClient class?

I have a console app built on .NET 4 that uses the HttpClient library (obtained via NuGet) to retrieve data from a public API over the internet. The console app sits behind a proxy. The Windows machine it sits on has the correct proxy settings in Internet Explorer. When the console application attempts to access the outside world it is given a 407 status - "proxy authentication required".

I've written no specific code to deal with a proxy yet. I'm assuming from the 407 error that the application is directing to the proxy no problem, but the proxy isn't authenticating the request.

My question is, is it possible to set the HttpClient to use the credentials of the logged in user to authenticate the proxy? If so, how?

var client = new HttpClient(webRequestHandler);
client.PostAsync(RequestUri, MyContent);

Solution

I managed to solve my problem very simply through proxy configuration in app.config.

<system.net>
    <defaultProxy enabled="true" useDefaultCredentials="true">
        <proxy usesystemdefault="True" />
    </defaultProxy>
</system.net>

http://msdn.microsoft.com/en-us/library/dkwyc043.aspx