PHP获取访问用户机器码（物理地址）

<?php
//获取用户电脑MAC地址并生成唯一机器识别码
    class GetMacAddr
    {
        var $return_array = array(); // 返回带有MAC地址的字串数组
        var $mac_addr;
        function GetMacAddr($os_type)
        {
            switch ( strtolower($os_type) )
            {
                    case "linux":
                            $this->forLinux();
                            break;
                    case "solaris":
                            break;
                    case "unix":
                            break;
                    case "aix":
                            break;
                    default:
                            $this->forWindows();
                            break;
            }
            $temp_array = array();
            foreach ( $this->return_array as $value )
            {
                    if ( preg_match( "/[0-9a-f][0-9a-f][:-]"."[0-9a-f][0-9a-f][:-]"."[0-9a-f][0-9a-f][:-]"."[0-9a-f][0-9a-f][:-]"."[0-9a-f][0-9a-f][:-]"."[0-9a-f][0-9a-f]/i", $value, $temp_array ) )
                    {
                            $this->mac_addr = $temp_array[0];
                            break;
                    }
            }
            unset($temp_array);
            return $this->mac_addr;
        }
        function forWindows()
        {
            @exec("ipconfig /all", $this->return_array);
            if ( $this->return_array )
                    return $this->return_array;
            else{
                    $ipconfig = $_SERVER["WINDIR"]."\system32\ipconfig.exe";
                    if ( is_file($ipconfig) )
                            @exec($ipconfig." /all", $this->return_array);
                    else
                            @exec($_SERVER["WINDIR"]."\system\ipconfig.exe /all", $this->return_array);
                    return $this->return_array;
            }
        }
    }
    $mac = new GetMacAddr(PHP_OS);
    echo $mac->mac_addr;
?>