Ensuring directory contents can’t be seen

Open the /etc/apache2/apache2.conf file:

sudo nano /etc/apache2/apache2.conf

Find this section:

<Directory /var/www/>
        Options Indexes FollowSymLinks
        AllowOverride None
        Require all granted
</Directory>

Options Indexes FollowSymLinks to:

Options -Indexes +FollowSymLinks

So it now looks like this:

<Directory /var/www/>
        Options -Indexes +FollowSymLinks
        AllowOverride None
        Require all granted
</Directory>

Save and close the file. Then, restart the Apache webserver:

sudo systemctl restart apache2