How does worker open the port?

<?php
use Workerman\Worker;
require_once __DIR__ . &#39;/Workerman/Autoloader.php&#39;;
$flash_policy = new Worker(&#39;tcp://0.0.0.0:843&#39;);
$flash_policy->onMessage = function($connection, $message)
{
    $connection->send(&#39;<?xml version="1.0"?><cross-domain-policy><site-control permitted-cross-domain-policies="all"/><allow-access-from domain="*" to-ports="*"/></cross-domain-policy>&#39;."\0");
};
if(!defined(&#39;GLOBAL_START&#39;))
{
    Worker::runAll();
}