Customizing the firewall
The Linux firewall is extremely versatile. So much in fact that it is practically impossible to offer all of its features through a GUI. The Bubbagen GUI will allow you to create basic input, forward and NAT rules but for more complex rules you will need to enter the console.
To allow additional rules from those controlled by the GUI, Bubbagen does not alter the main INPUT, FORWARD, PREROUTING and POSTROUTING chains like the original Bubba OS used to do, but instead controls its own dedicated chains. Please make sure to not remove the jumps to the Bubba_* chains from these main chains or the GUI method will no longer function.
As of version 1.12 the default firewall in Bubbagen uses nftables. This was necessary at the time because iptables required a higher kernel version than we were able to run on the B3 back then. The issue with the kernel has since been fixed and so it is perfectly possible to run iptables again but I decided to keep nftables as the default for Bubbagen.
Should you wish to switch to iptables you can do this by deleting the file /etc/portage/package.use/nftables and then run @world updates (with --newuse)