关于获取客户端Mac地址

private static string GetClientMAC()
        {
            string mac_dest = string.Empty;
            try
            {
                string strClientIP = HttpContext.Current.Request.UserHostAddress.ToString().Trim();
                Int32 ldest = inet_addr(strClientIP); //目的地的ip
                Int32 lhost = inet_addr("");   //本地服务器的ip
                Int64 macinfo = new Int64();
                Int32 len = ;
                int res = SendARP(ldest, , ref macinfo, ref len);
                string mac_src = macinfo.ToString("X");
                while (mac_src.Length < )
                {
                    mac_src = mac_src.Insert(, "");
                }
                for (int i = ; i < ; i++)
                {
                    if ( == (i % ))
                    {
                        if (i == )
                        {
                            mac_dest = mac_dest.Insert(, mac_src.Substring(i, ));
                        }
                        else
                        {
                            mac_dest = "-" + mac_dest.Insert(, mac_src.Substring(i, ));
                        }

                    }
                }
            }
            catch (Exception ex)
            {
                Log.Error("GetClientMAC", ex);
                //throw ex;
            }
            return mac_dest;
        }

上面的代码只能在局域网中使用，在广域网中是拿不到mac的（00-00-00-00-00-00），而且运行时间较长。