udp scan

<?php

$ip = '8.8.8.8';
$port = '53';
$timeout = 10; // seconds

$socket = socket_create(AF_INET, SOCK_RAW, getprotobyname('udp'));
if(!$socket) {
    die('Aborting');
}

require_once 'Hexdump.php';

$packet = pack (
 'nnnn', 0, $port, 8, 0
);

hexdump($packet);

socket_sendto($socket, $packet, strlen($packet), 0, $ip, $port);

while(TRUE){
    $read   = array($socket);
    $write  = NULL;
    $except = NULL;

    $select = socket_select($read, $write, $except, $timeout);
    if ($select === FALSE)
    {
        die(socket_strerror(socket_last_error($socket)));
    }

    if ($select === 0)
    {
        // timed out
        continue;
    }

    // we cannot receive the ICMP response in PHP, as the
    // PHP engine will handle this "for us" :|
    $ret = @socket_recvfrom($socket, $recv, 65535, 0, $host, $port);
    if(!$ret) {
        die(socket_strerror(socket_last_error($socket)));
    }

    echo "\n";
    hexdump($recv);

    // we got a response, the port is open
    die('port open');
}