Вы можете использовать функцию;
$ ipStr = "192.168.1.0/255";
function getIpsArrayFromStrRange($ipStr) {
$ipsArray = array();
//validate ip and check range existing
$regexp = '/^(\d{1,3})\.(\d{1,3})\.(\d{1,3})\.(\d{1,3})(\/(\d{1,3}))?$/';
$matches = array();
if(preg_match($regexp,$ipStr,$matches)){
//if it is a range
if(isset($matches[6])){
$min_ip = min($matches[4],$matches[6]);
$max_ip = max($matches[4], $matches[6]);
for($i=$min_ip; $i<=$max_ip; $i++){
$ipsArray[] = "$matches[1].$matches[2].$matches[3].$i";
}
}else{
$ipsArray[] = $ipStr;
}
return $ipsArray;
}else{
return false;
}
}