How to Make iptables Firewall Rules Persistent on Debian/Ubuntu
Here's how to keep iptables firewall rules persistent between reboots so you don’t lose them after the system is rebooted.
Firewalld 1.0 Firewall Management Tool is Here with Big Improvements
Ten years after its first release, Firewalld reached version 1.0. The biggest change is removing Python 2 support.