Due to mutiple scans on the xmlrpc protocol, i chose to protect xmlrpc.php file with .htaccess.

<Files xmlrpc.php>
Order deny,allow
Deny from all
Allow from 188.24
Allow from 188.27
</Files>

The problem is that, if I want to update Jetpack, it shows the following message:

Your website needs to be publicly accessible to use Jetpack: site_inaccessible

Error Details: The Jetpack server was unable to communicate with your site [HTTP 403]. Ask your web host if they allow connections from WordPress.com. If you need further assistance, contact Jetpack Support: http://jetpack.me/support/

At first, i did not know why and the internet offers little support. After some digging, I found out the problems are connected. I removed the

Deny from all

line and I could activate Jetpack.