Asp.net MVC获取访问系统的客户端计算机的主机名和IP地址

string HostName = string.Empty;
string ip = string.Empty;
string ipv4 = String.Empty;

if (!string.IsNullOrEmpty(System.Web.HttpContext.Current.Request.ServerVariables["HTTP_VIA"]))
     ip = Convert.ToString(System.Web.HttpContext.Current.Request.ServerVariables["HTTP_X_FORWARDED_FOR"]);
if (string.IsNullOrEmpty(ip))
     ip = Request.UserHostAddress;

 // 利用 Dns.GetHostEntry 方法，由获取的 IPv6 位址反查 DNS 纪录，
 // 再逐一判断何者为 IPv4 协议，即可转为 IPv4 位址。
foreach (IPAddress ipAddr in Dns.GetHostEntry(ip).AddressList)
{
    if (ipAddr.AddressFamily.ToString() == "InterNetwork")
    {
        ipv4 = ipAddr.ToString();
    }
}

HostName = "主机名: " + Dns.GetHostEntry(ip).HostName + " IP: " + ipv4;

　　在本机进行程序代码调试测试，其中字符串ip会显示为::1，是IPv6的IP地址格式，相当于127.0.0.1。最终处理成IPv4的显示地址。

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上述方法，代码调试没有问题，但是放在服务器上后，客户端访问就出问题了，有部分电脑能获取主机名，但是ipv4显示为空，另外一部分

Dns.GetHostEntry(ip)中的ip正常，但是执行Dns.GetHostEntry(ip)貌似为null，导致出现异常。最后选择的方法是只记录客户端的IPV4，

/// <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) ==  || String.IsNullOrEmpty(CustomerIP))
                {
                    return System.Web.HttpContext.Current.Request.UserHostAddress;
                }
                return CustomerIP;
            }
            catch { }

            return userIP;

        }