由于目标机器主动拒绝连接，所以无法连接？

Question

由于目标机器主动拒绝连接，所以无法连接？有时，当我对WebService执行HttpWebRequest时，会收到以下错误。下面我也复制了我的代码。ServicePointManager.CertificatePolicy = new TrustAllCertificatePolicy();HttpWebRequest request = (HttpWebRequest)WebRequest.Create(url); request.PreAuthenticate = true;request.Credentials = networkCredential(sla);request.Method = WebRequestMethods.Http.Post; request.ContentType = "application/x-www-form-urlencoded";request.Timeout = v_Timeout * 1000; if (url.IndexOf("asmx") > 0 && parStartIndex > 0){     AppHelper.Logger.Append("#############" + sla.ServiceName);     using (StreamWriter reqWriter = new StreamWriter(request.GetRequestStream()))     {                                 while (true)         {             int index01 = parList.Length;             int index02 = parList.IndexOf("=");             if (parList.IndexOf("&") > 0)                 index01 = parList.IndexOf("&");             string parName = parList.Substring(0, index02);             string parValue = parList.Substring(index02 + 1, index01 - index02 - 1);             reqWriter.Write("{0}={1}", HttpUtility.UrlEncode(parName), HttpUtility.UrlEncode(parValue));              if (index01 == parList.Length)                  break;              reqWriter.Write("&");              parList = parList.Substring(index01 + 1);          }      }  }  else  {      request.ContentLength = 0;  }  response = (HttpWebResponse)request.GetResponse();