After having used a DIY firewall I put together in around 2007, circumstances (COVID-19 social-distancing) have provided an opportunity to rething my firewall.
This project will provide a much better environment for managing my firewall. If there is no other improvement, having the IPTables rules under source control will increase the safety of experimenting with different IPTables ideas.
I expect that the scripts will be BASH scripts, as it's the most direct way to interact with the CLI interface of IPTables.
The firewall will also be a DHCP server. I will include a link to a page that seems helpful now, and I may add additional pages if needed and they merit.
In an older NAT installation, one added a '1' to the ip_forward and ip_dynaddr files in /proc/sys/net/ipv4 directory. Newer instructions, found in these quick tips informed me that I have to make changes in the /etc/sysctl.conf file. Look in new_iptables for the sed script that makes the changes.