C#自動獲取本機外網ip

public static string GetIP()
        {
            using (var webClient = new WebClient())
            {
               try{
                    webClient.Credentials = CredentialCache.DefaultCredentials;
                    byte[] pageDate = webClient.DownloadData("http://pv.sohu.com/cityjson?ie=utf-8");
                    String ip = Encoding.UTF8.GetString(pageDate);
                    webClient.Dispose();

                    Match rebool = Regex.Match(ip, @"\d{2,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}");
                    return rebool.Value;
               }
               catch (Exception e)
               {
                   return "";
               }

            }
        }