A bit off topic, but I'm nominating grawity for Top Answer of the Week:
How to avoid exposing my MAC address when using IPv6?
This is what IPv6 Privacy Addressing is for. When enabled, the system will generate a temporary address with a random suffix in addition to the EUI-64-based address.
[many, many, more details]
The key is:
Grawity answered my question before I asked it. Even more: before I knew I had that question!
The full story:
I'd always assumed that I could not stop exposing my MAC address in my IPv6 addresses, as I did not find any settings for that in my router. Kudos for the commenting system, as enters grawity on one of my answers, hinting that it's not a thing of a router to start with:
Re footnote #2 - see "privacy addressing". – grawity 22 hours ago
Yup, @grawity, I noticed that extension being mentioned in RFCs, but failed to find any related settings in my consumer grade modem/router to allow for that. :-( – Arjan 22 hours ago
@Arjan: If your network is using IPv6 Autoconfiguration, then the address suffix is chosen by your own PC and this is where you should look for Privacy Addressing too. On Linux,
sysctl net.ipv6.conf.eth0.use_tempaddr=1; on Windows it's
netsh inter ipv6 set privacy (on by default). – grawity 20 hours ago
On a Mac:
sudo sysctl -w net.inet6.ip6.use_tempaddr=1 (default value: 0). After that:
ifconfig shows two IPv6 addresses; test-ipv6.com and ipv6-test.com show the temporary address. – Arjan 18 hours ago
Next, I posted this as a question, as I needed some reference when re-editing some other posts in which earlier I boldly added that IPv6 addresses often included the computer's MAC address. Given the number of favorites, I guess there were more people oblivious about having this question. :-)