WebHelper

 /// <summary>
        /// 获取web客户端ip
        /// </summary>
        /// <returns></returns>
        public static string GetWebClientIp()
        {
            try
            {
                if (HttpContext.Current == null
                    || HttpContext.Current.Request == null
                    || HttpContext.Current.Request.ServerVariables == null)
                    return "";

                string CustomerIP = "";

                //CDN加速后取到的IP
                CustomerIP = HttpContext.Current.Request.Headers["Cdn-Src-Ip"];
                if (!string.IsNullOrEmpty(CustomerIP))
                {
                    return CustomerIP;
                }

                if (HttpContext.Current.Request.ServerVariables["HTTP_VIA"] != null)
                {
                    CustomerIP = HttpContext.Current.Request.ServerVariables["HTTP_X_FORWARDED_FOR"];
                    if (CustomerIP == null)
                        CustomerIP = HttpContext.Current.Request.ServerVariables["REMOTE_ADDR"];
                }
                else
                {
                    CustomerIP = HttpContext.Current.Request.ServerVariables["REMOTE_ADDR"];

                }

                if (string.Compare(CustomerIP, "unknown", true) == 0)
                    return HttpContext.Current.Request.UserHostAddress;
                return CustomerIP;
                /** lcq
                关键就在HTTP_X_FORWARDED_FOR
                使用不同种类代理服务器，上面的信息会有所不同：

                一、没有使用代理服务器的情况：
                REMOTE_ADDR = 您的 IP
                HTTP_VIA = 没数值或不显示
                HTTP_X_FORWARDED_FOR = 没数值或不显示

                二、使用透明代理服务器的情况：Transparent Proxies
                REMOTE_ADDR = 代理服务器 IP 
                HTTP_VIA = 代理服务器 IP
                HTTP_X_FORWARDED_FOR = 您的真实 IP
                这类代理服务器还是将您的信息转发给您的访问对象，无法达到隐藏真实身份的目的。

                三、使用普通匿名代理服务器的情况：Anonymous Proxies
                REMOTE_ADDR = 代理服务器 IP 
                HTTP_VIA = 代理服务器 IP
                HTTP_X_FORWARDED_FOR = 代理服务器 IP
                隐藏了您的真实IP，但是向访问对象透露了您是使用代理服务器访问他们的。

                四、使用欺骗性代理服务器的情况：Distorting Proxies
                REMOTE_ADDR = 代理服务器 IP 
                HTTP_VIA = 代理服务器 IP 
                HTTP_X_FORWARDED_FOR = 随机的 IP
                告诉了访问对象您使用了代理服务器，但编造了一个虚假的随机IP代替您的真实IP欺骗它。

                五、使用高匿名代理服务器的情况：High Anonymity Proxies (Elite proxies)
                REMOTE_ADDR = 代理服务器 IP
                HTTP_VIA = 没数值或不显示
                HTTP_X_FORWARDED_FOR = 没数值或不显示 
                **/
            }
            catch (Exception)
            {
                return string.Empty;
            }
        }

        /// <summary>
        /// 获取服务器IP
        /// </summary>
        /// <returns></returns>
        public static string GetLocalIp()
        {
            try
            {
                var ipHostEntry = Dns.GetHostEntry(Dns.GetHostName());
                var address = ipHostEntry.AddressList.FirstOrDefault(i => i.AddressFamily == AddressFamily.InterNetwork);
                var localIpAddress = address == null ? string.Empty : address.ToString();
                return localIpAddress;
            }
            catch (Exception)
            {
                return string.Empty;
            }  
        }