cidr.php

#!/usr/bin/env php
<?php
if ($argc !== 2) {
	echo "Usage: ".$argv[0]." 127.0.0.1/8";
	exit;
}
list($ip, $net) = explode('/', $argv[1]);
if ($net > 32 || $net < 0) exit;
$long = ip2long($ip);
$size = $net;
$long = $long & ~((1 << (32 - $size)) - 1);

for ($start = $long; ($long & ~((1 << (32 - $size)) - 1)) == ($start & ~((1 << (32 - $size)) - 1)); $long++) {
	echo long2ip($long)."\n";
}