$re = '/^((?=[0-9.]+$)((25[0-5]|(2[0-4]|1[0-9])[0-9]|[1-9]?[0-9])\.){3}(25[0-5]|(2[0-4]|1[0-9])[0-9]|[1-9]?[0-9])|(?=[0-9.]*[a-zA-Z])([a-zA-Z0-9]|[a-zA-Z0-9][a-zA-Z0-9-]{0,61}[a-zA-Z0-9])((\.([a-zA-Z0-9]|[a-zA-Z0-9][a-zA-Z0-9-]{0,61}[a-zA-Z0-9]))*(\.[a-zA-Z]{2,31}))+)$/m';
$str = '127.0.0.1
192.168.1.1
192.168.1.255
192.168.255.255
0.0.0.0
127.0.0.1
192.168.1.1a
192.068.1.255
30.168.1.255.1
127.1
192.168.1.256
-1.2.3.4
1.1.1.1.
3...3
toto.fr
truc-bidule.com
sub.truc-bidule.toto.com
toto
toto.f
toto.f6
-3.fr
toto.fr
truc_bidule.com
sub..truc-bidule.toto.com
';
preg_match_all($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