$re = '/^((?&byte))\.((?&byte))\.((?&byte))\.((?&byte))$(?(DEFINE)(?<byte>25[0-5]|2[0-4]\d|[01]?\d\d?))/m';
$str = '128.0.25.120
255.255.255.255
0.0.0.0
102.10.0i.10';
preg_match_all($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