Comment by RiverCrochet

> This is _gone_ with IPv6

Incorrect. There is the ULA range, fc00::/7, which is not routable and can be used in the same place you'd use 192.168.0.0/16 or similar.

You can even do something like fc00::192:168:0:0/120 if you really want.

> There is really no reason for most devices to be publicly reachable.

If you want things to work in one direction only, you really want television or radio. This is how most people really treat the Internet, unfortunately.