===== Debian firewalld =====
<code>
apt-get install firewalld
firewall-cmd --permanent --zone=drop --change-interface=eth0
firewall-cmd --permanent --add-port=10001/tcp --zone=drop
firewall-cmd --permanent --add-port=5000/tcp --zone=drop
firewall-cmd --reload
</code>

==== References ====
  * https://ec.europa.eu/digital-building-blocks/sites/display/CEKB/How+to+open+a+port+on+the+firewall
  * https://serverfault.com/questions/748946/firewalld-not-listing-any-active-zones