For people who are hacking away at the Raspberry Pi and are security minded, I just ran into this article on Bruce Schneier's blog: "Take These Steps to Secure Your Raspberry Pi Against Attackers," https://makezine.com/2017/09/07/secure-your-raspberry-pi-against-attackers/

Hardening the device may limit your ability to use a digital assistant and you are likely to need to create exceptions in the firewall.