[johansch]

"IPs are just too ephemeral to trust for any form of location data"

That is just policy decision. It would, for example, be possible to declare that no single IP should be used for more than two customers during a single X hour block.

[falcolas]

A policy decision by whom? Specifically, how do you do this when IP spaces are controlled by various unfriendly countries around the world? Politics aside, the required technical coordination would be a nightmare. We can barely handle BGP without conflicts as-is.

IPv4 space is also quite limited, and new devices are popping onto networks all the time. I'm not even sure a IP time window is feasible without a full move to IPv6 - something that policy makers have been trying to push on for years without success.

[johansch]

>A policy decision by whom?

By your government?

> Specifically, how do you do this when IP spaces are controlled by various unfriendly countries around the world

You begin a "911-certified program" that requires your local ISPs to register their IP ranges with some central authority. The rest is a bunch of detailed but solvable details.

Your idealism when it comes to making this seem more complicatated that it really is seems misplaced.