获取客户端Mac

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Runtime.InteropServices;

namespace WebApplication1
{
    public class test
    {
        [DllImport("Iphlpapi.dll")]
        private static extern int SendARP(Int32 dest, Int32 host, ref   Int64 mac, ref   Int32 length);
        [DllImport("Ws2_32.dll")]
        private static extern Int32 inet_addr(string ip);

        ///<summary>
        ///得到客户端ip
        ///</summary>
        ///<returns>ip</returns>
        private string GetClientIP()
        {
            string result = HttpContext.Current.Request.ServerVariables["HTTP_X_FORWARDED_FOR"];
            if (null == result || result == String.Empty)
            {
                result = HttpContext.Current.Request.ServerVariables["REMOTE_ADDR"];
            }
            if (null == result || result == String.Empty)
            {
                result = HttpContext.Current.Request.UserHostAddress;
            }
            return result;
        }

        ///<summary>
        /// 利用客户端ip得到客户端mac
        ///</summary>
        ///<param name="remoteip">客户端ip</param>
        ///<returns>int16类型的mac</returns>
        static private Int64 getremotemac(string remoteip)
        {
            Int32 ldest = inet_addr(remoteip);
            try
            {
                Int64 macinfo = new Int64();
                Int32 len = 6;
                int res = SendARP(ldest, 0, ref   macinfo, ref   len);
                return macinfo;
            }
            catch (Exception err)
            {
                Console.WriteLine("error:{0}", err.Message);
            }
            return 0;
        }

        ///<summary>
        /// int64类型的mac转换成正确的客户端mac
        ///</summary>
        ///<returns>mac</returns>
        public string GetClientMAC()
        {
            Int64 macid = getremotemac(GetClientIP());
            if (macid == 0)
                return "0";
            //string beforeMacAddr = Convert.ToString(macid, 16);
            string beforeMacAddr = macid.ToString("X");
            while (beforeMacAddr.Length < 12)
            {
                beforeMacAddr = beforeMacAddr.Insert(0, "0");
            }
           // string beforeMacAddr = macid.ToString("X");
            string endMacAddr = "";
            string[] macArray = new string[6];
            for (int i = 0; i < 6; i++)
            {
                    macArray[i] = beforeMacAddr.Substring(i * 2, 2);               
            }
            for (int i = 0; i < 6; i++)
            {
                endMacAddr += macArray[5 - i] + "-";
            }
            endMacAddr = endMacAddr.Substring(0, endMacAddr.Length - 1);
            endMacAddr = endMacAddr.ToUpper();
            return endMacAddr;
        }
    }
}