<?php
if(!isset($_SERVER['HTTP_USER_AGENT']))
{
    header("HTTP/1.0 404 Not Found");
}
?>

https://wordpress.org/plugins/bbpress/

https://developer.mozilla.org/en-US/docs/Web/API/Notifications_API/Using_the_Notifications_API

https://developers.google.com/web/fundamentals/codelabs/push-notifications/