How to block access to sites by link?

Question

Nginx

Hello. Please tell me, I have a site, for example site.ru, I am being attacked by a DDoS attack of the l7 level, how to prohibit access to the site using a link of this type site.ru/?GHBGFFUJN. Thanks in advance

Answer 1

at the nginx level

if ($arg_GHBGFFUJN) {
    return 444;
}

at the PHP level,
in the case of laravel, you can enter directly at the beginning of the filepublic/index.php

if(isset($_GET['GHBGFFUJN'])) {
    http_response_code(403);
    exit;
}

it is better to block requests at the nginx level so that they do not reach PHP and do not create additional. load.
also, if all requests have the same pattern, for example, they contain GHBGFFUJN, then you can get ip from access logs from which such requests arrive, and add ip to the block already at the firewall level, for 30 minutes.