Thanks for the great work! I've been waiting to get under the hood of this thing.
I waited for a few years with my KW4 (G0000 PP13), making my firmware rather obsolete but also avoiding the latest locked up firmware. I had to scrounge around looking for the firmware files. The only ones that finally worked were named with the format update_kindle_all_new_paperwhite_v2_5.14.1.bin and were a pain to guess around in the amazon url namespace. I yeeted all of it to
https://turrican.uraanikaivos.com/pub/kindlestuff just in case it helps anyone.
Firewall configuration is stored under /etc/sysconfig/iptables. Fixed to make my SSH port open to wireless for ease of use. I opted to redirect all communication from the kindle to ports 80 and 443 to the local firewall, making the kindle think that it's behind a paywalled wireless connection.