$re = '/([0-9A-Fa-f]{2}[:]){5}([0-9A-Fa-f]{2})/mu';
$str = 'Devices:\\n\\thci1\\t00:50:B6:80:4D:5D\\n\\thci0\\t00:15:83:15:A2:CB\\n';
preg_match_all($re, $str, $matches, PREG_SET_ORDER, 0);
// Print the entire match result
var_dump($matches);
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for PHP, please visit: http://php.net/manual/en/ref.pcre.php