C# 正则获取外网Ip

/// <summary>

        /// 获取外网Ip

        /// </summary>

        /// <returns></returns>

        public static string GetInternetIP()

        {

            try

            {

                string strUrl = "http://iframe.ip138.com/ic.asp";

                System.Uri uri = new System.Uri(strUrl);

                System.Net.WebRequest wr = System.Net.WebRequest.Create(uri);

                System.IO.Stream s = wr.GetResponse().GetResponseStream();

                System.IO.StreamReader sr = new System.IO.StreamReader(s, System.Text.Encoding.Default);

                string all = sr.ReadToEnd();   

                sr.Close();

                wr.Abort();




                System.Text.RegularExpressions.Match m = System.Text.RegularExpressions.Regex.Match(all, @"\b(([01]?\d?\d|2[0-4]\d|25[0-5])\.){3}([01]?\d?\d|2[0-4]\d|25[0-5])\b");

                if (m.Success)

                {

                    return m.Groups[0].Value;

                }

                else

                {

                    return string.Empty;

                }

            }

            catch

            {

                return string.Empty;

            }

        }