Thank you for pointing this out. I am aware of iptables and the blocking setup is among the top ones in my TODO list.
And I am OK to admit my "unreasonable paranioa"
But this way of connection with KUAL is just brilliant idea

and moves it to the next level.
My thinking about firewall was about a bit different setup, though.
Something like this
- ACCEPT all LAN IPs ranges
- ACCEPT white-listed IPs
- DROP all know evil addresses
- LOG into file system remaining attempts
- default policy: DROP
+ be able to see the log w/o connecting Kindle to PC. In KUAL (ideal, if possible) or as an eBook (less elegant)
But in first place I need to investigate if logging would be even possible. So this is where the fun part begins...