$re = '/(?<address>\d{1,3}(?:\.\d{1,3}){2}\.(?<FromSeg>\d{1,3}))(?:(?:\/|\s+\/\s+)(?<CIDR>\d{1,2})|(?:-|\s+to\s+)(?<ToSeg>\d{1,3}(?![\d\.]))|(?:-|\s*to\s+)(?<ToIP>\d{1,3}(?:\.\d{1,3}){3})|\s+(?<Mask>25\d(?:\.\d{1,3}){3})|\s*)?/';
$str = '56.1.2.3/24
56.1.2.4-7
56.1.2.4-255.0.0.0
56.1.2.4 to 7
56.1.2.4 to 56.1.2.7
56.1.2.3 / 24
56.1.2.3
';
preg_match_all($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