获取客户端真实ip地址(无视代理)

 /// <summary>
         /// 获取客户端IP地址（无视代理）
         /// </summary>
         /// <returns>若失败则返回回送地址</returns>
         public static string GetHostAddress()
         {
             string userHostAddress = HttpContext.Current.Request.ServerVariables["REMOTE_ADDR"];
             if (string.IsNullOrEmpty(userHostAddress))
             {
                 if (System.Web.HttpContext.Current.Request.ServerVariables["HTTP_VIA"] != null)
                     userHostAddress = HttpContext.Current.Request.ServerVariables["HTTP_X_FORWARDED_FOR"].ToString().Split(',')[].Trim();
             }
             if (string.IsNullOrEmpty(userHostAddress))
             {
                 userHostAddress = HttpContext.Current.Request.UserHostAddress;
             }

             //最后判断获取是否成功，并检查IP地址的格式（检查其格式非常重要）
             if (!string.IsNullOrEmpty(userHostAddress) && IsIP(userHostAddress))
             {
                 return userHostAddress;
             }
             return "127.0.0.1";
         }

         /// <summary>
         /// 检查IP地址格式
         /// </summary>
         /// <param name="ip"></param>
         /// <returns></returns>
         public static bool IsIP(string ip)
         {
             return System.Text.RegularExpressions.Regex.IsMatch(ip, @"^((2[0-4]\d|25[0-5]|[01]?\d\d?)\.){3}(2[0-4]\d|25[0-5]|[01]?\d\d?)$");
         }