$re = '/^(ldap(s)?:\/\/)(((\d{1,3}.){3}\d{1,3}(:\d+)?)|(\w|\d|)+|((\[([a-f0-9]{1,4}:{1,2}){1,4}([a-f0-9]{1,4})\])(:\d+)?)).\w+$/m';
$str = 'ldap://127.0.0.1:389
ldap://127.0.0.1
ldap://mydomain.test
ldaps://[fe80:4049:92ff:fe44:4bd1]:5060
ldap://[fe80::4bd1]:5060';
preg_match_all($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