Block ping using iptables in Ubuntu
https://pupli.net/2019/08/block-ping-using-iptables-in-ubuntu/
Make iptables rules persistent after reboot on Ubuntu 18.04
https://pupli.net/2019/08/make-iptables-rules-persistent-after-reboot-on-ubuntu-18-04/
How To List and Delete Iptables Firewall Rules on Ubuntu 16.04
https://pupli.net/2018/01/how-to-list-and-delete-iptables-firewall-rules-on-ubuntu-16-04/