SergeChel Log

IWebProxy proxy = WebRequest.GetSystemWebProxy();
proxy.Credentials = System.Net.CredentialCache.DefaultCredentials;
request.Proxy = proxy;

WebProxy proxy = new WebProxy("_proxy_uri_here", true);
CredentialCache credentials = new CredentialCache();
credentials.Add("_proxy_uri_here_", "Basic", 
    new NetworkCredential("_username_", "_password_"));
proxy.Credentials = credentials;
request.Proxy = proxy;