/**//// <summary>
    /// RealIP 的摘要说明：
    /// 获得用户的真实ip，由于squidserver的原因直接取到的ip是内网ip
    /// </summary>
    abstract public class RealIP
    {
        const string HEADER_KEY_IP = "X-Forwarded-For";

        /**//// <summary>
        /// 真实ip
        /// </summary>
        public static string Value
        {
            get
            {
                System.Web.HttpRequest request = System.Web.HttpContext.Current.Request;
                string ip = string.Empty;
                string ipHeader = request.Headers[HEADER_KEY_IP];
    
                if(!string.IsNullOrEmpty(ipHeader))
                {
                    string[] IPs = ipHeader.Split(',');
                    foreach (string ipItem in IPs)
                    {
                        if ((!string.IsNullOrEmpty(ipItem)) && (!IsLocalIP(ipItem)))
                        {
                            ip = ipItem;
                            break;
                        }
                    }
                }
                if(ip == string.Empty)ip = request.UserHostAddress;
                return ip;
            }
        }

        static bool IsLocalIP(string ip)
        {
            return ip.StartsWith("192.168.") || ip.StartsWith("172.16.") || ip.StartsWith("10.");
        }
    }