public class IPAdress    {        public static bool isIP(string str1)        {            if (str1 == null || str1 == string.Empty || str1.Length < 7 || str1.Length > 15) return false;            string regformat = @"^\d{1,3}[\.]\d{1,3}[\.]\d{1,3}[\.]\d{1,3}$";            Regex regex = new Regex(regformat, RegexOptions.IgnoreCase);            return regex.IsMatch(str1);        }        /// 
        /// 取得客户端真实IP。如果有代理则取第一个非内网地址        /// 
        public static string fetch()        {            string result = String.Empty;            result = HttpContext.Current.Request.ServerVariables["HTTP_X_FORWARDED_FOR"];            if (result != null && result != String.Empty) {                if (result.IndexOf(".") == -1)                    result = null;                else {                    if (result.IndexOf(",") != -1) {                        result = result.Replace(" ", "").Replace("'", "");                        string[] temparyip = result.Split(",;".ToCharArray());                        for (int i = 0; i < temparyip.Length; i++) {                            if (isIP(temparyip[i])                                && temparyip[i].Substring(0, 3) != "10."                                && temparyip[i].Substring(0, 7) != "192.168"                                && temparyip[i].Substring(0, 7) != "172.16.") {                                return temparyip[i];                            }                        }                    } else if (isIP(result))                        return result;                    else                        result = null;                }            }            string IpAddress = (HttpContext.Current.Request.ServerVariables["HTTP_X_FORWARDED_FOR"] != null && HttpContext.Current.Request.ServerVariables["HTTP_X_FORWARDED_FOR"] != String.Empty) ? HttpContext.Current.Request.ServerVariables["HTTP_X_FORWARDED_FOR"] : HttpContext.Current.Request.ServerVariables["REMOTE_ADDR"];            if (null == result || result == String.Empty)                result = HttpContext.Current.Request.ServerVariables["REMOTE_ADDR"];            if (result == null || result == String.Empty)                result = HttpContext.Current.Request.UserHostAddress;            return result;        }    }