apache2: Could not reliably determine the server's fully qualified domain name, using 127.0.1.1 for ServerName

echo ServerName $HOSTNAME > /etc/apache2/conf.d/fqdn

Apache: change default port 80 into 8080

Edit /etc/apache2/ports.conf and change:

Listen 80

into:

Listen 8080

And restart apache:

$ sudo service apache2 restart

Apache: enable/disable directory browsing (file listing)

disable file listing
assume we want to disable file listing in /var/www (i.e. all directories)

$ sudo cat /var/www/.htaccess
# disable directory listing
Options -Indexes