通过外部网站返回得到内网外部IP

static string GetIP() { Uri uri = new Uri("http://www.ikaka.com/ip/index.asp";); System.Net.HttpWebRequest req = (System.Net.HttpWebRequest)System.Net.WebRequest.Create(uri); req.Method = "POST"; req.ContentType = "application/x-www-form-urlencoded"; req.ContentLength = 0; req.CookieContainer = new System.Net.CookieContainer(); req.GetRequestStream().Write(new byte [0], 0, 0); System.Net.HttpWebResponse res = (System.Net.HttpWebResponse)(req.GetResponse()); StreamReader rs = new StreamReader(res.GetResponseStream(), System.Text.Encoding.GetEncoding("GB18030")); string s = rs.ReadToEnd(); rs.Close(); req.Abort(); res.Close(); System.Text.RegularExpressions.Match m = System.Text.RegularExpressions.Regex.Match(s, @"IP：/[(?<IP>[0-9/.]*)/]"); if (m.Success) return m.Groups["IP"].Value; return string.Empty; }