Supplying dedicated credentials for firewall or proxy authentication

For WCF services over the HTTP transport protocol, it is possible that the server machine and client callers are located in different network environments and the client might need to pass some intermediate firewall or proxy to reach the server endpoint. If the proxy or firewall requires client authentication, the WCF client consumer also needs to supply credentials for the firewall or proxy server in addition to the authentication of the WCF service endpoint itself. If you're familiar with .NET HttpWebRequest programming, you will find it quite straightforward to handle this kind of web proxy authentication, since HttpWebRequest type provides a Proxy property (of System.Net.WebProxy type) that lets developers assign proxy information, including the authentication credentials (see the following code snippet):

HttpWebRequest req = 
(HttpWebRequest)WebRequest.Create("http://www.msn.com");

req.Proxy.Credentials = new System...