xmen

Hello, I am using <?php $ip = $_SERVER['REMOTE_ADDR']; $arp = "/usr/sbin/arp"; $mac = shell_exec("sudo $arp -an " . $ip); preg_match('/..:..:..:..:..:../',$mac , $matches); $mac = @$matches[0]; echo $mac ?> to see/verify in my browser if there will be a return for echo $mac, but there is nothing appearing on the webpage and using var_dump($mac) returns NULL on the webpage. Basically, I would want to get the client mac address on LAN. Hoping for your favorable response. Thank you.