[syncsynchalt]

A few things:

- several years ago your MAC address was used in the latter 64 bits of your network to create your public address (not just your link local).

- that naïveté/mistake has been addressed by OS makers since.

- your ISP gives you the first half of your 128-bit IP address, the second half is up to your device(s). This is baked in pretty deeply at this point, so the smallest allocation any user/router/LAN will get is 2^64 addresses. This is 4 billion times 4 billion. With that much address space we have a lot of room for competing schemes for address selection, up to and including generating random numbers. The early use of static addresses based on MAC addresses was largely convenience and holdover from v4 thinking.

[scott_karana]

Is the MAC addr behavior in Linux, at least, modifiable? Either through a kernel rebuild or a runtime variable?

[MrRadar]

Yes, see https://home.regit.org/2011/04/ipv6-privacy/