获取外网访问者的真实ip，在线等待
HttpWebRequest req = (HttpWebRequest)HttpWebRequest.Create("http://www.ip138.com/ip2city.asp");
req.Method = "POST";
req.ContentType = "application/x-www-form-urlencoded";
req.ContentLength = 0;
req.CookieContainer = new CookieContainer();
req.GetRequestStream().Write(new byte[0], 0, 0);
WebResponse res = req.GetResponse();
StreamReader rs = new StreamReader(res.GetResponseStream(), Encoding.GetEncoding("gb2312"));
string s = rs.ReadToEnd();
rs.Close();
req.Abort();
res.Close();
Match m = Regex.Match(s, @"(\d+)\.(\d+)\.(\d+)\.(\d+)");

string ipHost = string.Empty;



到这 WebResponse res = req.GetResponse();一步报远（程服务器返回错误: (403) 已禁止。）求解

[解决办法]
参考1：

C# code

string GetInternalIpAddress1()        {            try            {                string strUrl = "http://www.3322.org/dyndns/getip"; //获得IP的网址了                   Uri uri = new Uri(strUrl);                WebRequest wr = WebRequest.Create(uri);                Stream s = wr.GetResponse().GetResponseStream();                StreamReader sr = new StreamReader(s, Encoding.Default);                string all = sr.ReadToEnd(); //读取网站的数据                   all = all.Replace("\r\n", "");                return all;            }            catch (Exception ex)            {                return "";            }        }