- var_dump: documentation ( source)
- preg_match: documentation ( source)
<?php
$str = '00:18:71:EC:38:58/072b8d45-895d-4d9d-9adb-e1502d6821d9.xml';
preg_match('/^(([0-9A-F]{2}[:-]){5}[0-9A-F]{2})+[\/]+([0-9a-z-]+[.]+[a-z]{3})$/', $str, $match);
var_dump($match);
$mac = $match['1'];
$regkey = $match['3'];