asp.net MVC 发布的放于服务器网站无法获取客户端IP

[liusa1997]

当用户访问主页面会记录下用户的IP信息，但是我用了如下代码：（只能记录本机访问的IP，然而外网的无法记录）

/// <summary>
        /// 获取web客户端ip
        /// </summary>
        /// <returns></returns>
        public static string GetWebClientIp()
        {

            string userIP = "未获取用户IP";

            try
            {
                if (System.Web.HttpContext.Current == null
                 || System.Web.HttpContext.Current.Request == null
                 || System.Web.HttpContext.Current.Request.ServerVariables == null)
                {
                    return "";
                }

                string CustomerIP = "";

                //CDN加速后取到的IP simone 090805
                CustomerIP = System.Web.HttpContext.Current.Request.Headers["Cdn-Src-Ip"];
                if (!string.IsNullOrEmpty(CustomerIP))
                {
                    return CustomerIP;
                }

                CustomerIP = System.Web.HttpContext.Current.Request.ServerVariables["HTTP_X_FORWARDED_FOR"];

                if (!String.IsNullOrEmpty(CustomerIP))
                {
                    return CustomerIP;
                }

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

                if (string.Compare(CustomerIP, "unknown", true) == 0 || String.IsNullOrEmpty(CustomerIP))
                {
                    return System.Web.HttpContext.Current.Request.UserHostAddress;
                }
                return CustomerIP;
            }
            catch { }

            return userIP;

        }

由于服务器不好调试，所以不知道问题出在哪里，怎么解决这个问题？需要穿透吗？