No they can't: the whole point of RFC4941/8981 is to prevent that. The source address for external connections is effectively randomized.
All that can be inferred is that it came from your network, but even with NAT you know that anyway.
It's still unique to one device right?, even if random my argument still holds.
Or do you mean to say multiple devices can use the same address?
note: I've read the RFCs and they just mean - initial address is random but unique to a device. Each day the address will likely change but new address is still unique to the device (otherwise how would routing work).
This is what I structured my inital argument on. Do you see any fallacy in logic?
Once identity is known for address X you know its traffic for the day, including past traffic for the day.
once address changes you do the whole identification again.
All these logs where address is identified goes to bucket X.
On addresses where you couldnt identify that day you put them in unknown bucket.
Once you have a profile of the network, you can do exclusion (Only 4 people in household, 3 active with known addresses, not X, one unknown address, you can assume its X)
The “I don’t care if they track my household but it’s critical that Daddy’s activity not get disambiguated from my dealing daughter” is just not a valid reason to abandon the benefits of IPv6.
Please stop with this line of argument.
If you’re really desperate to ensure that the ads shown to your daughter are based on your porn viewing habits, then just set up IPv6 NAT.
That's a broad assumption, and I can assure you they will due to lower costs (no need to pay data broker if you already know target, no need for extra traffic, load, etc). Also due to better targetting you get better prices per ads served.
> just not a valid reason to abandon the benefits of IPv6
What are the benefits to allow each device its own address if I'm going to firewall them anyway?
> Please stop with this line of argument.
Why?, my concern is valid, all you've said so far is nobody cares. I disagree.
> If you’re really desperate to ensure that the ads shown to your daughter are based on your porn viewing habits, then just set up IPv6 NAT
That says a lot about yourself if you resort to this sort of snarky comments, I have no wish to continue this conversation.
Note: I said in another comment I have set up IPv6 NAT and it works great.
If I told my security information officer "We don't protect against foreseeable threat X because we assume no one will bother to try X" she would not be very happy with me.
When a valid data concern has been expressed and described, putting your head in the sand is the incorrect response. I want IPv4 to die as much as the next person but at a minimum organizations such as hospitals and government installations will not accept that sort of outside visibility into their network.
I don’t quite feel convinced yet by this argument.
For example, one essential difference is that while it’s true that my web browser does have those leaks, I can be reasonably sure that it’s only leaking to specific hosts, i.e. the one I’m visiting and its embedded resources.
Tracking on the IP source address level, however, would be a whole other thing: that means that whoever happens to see the byte stream can now track who is visiting what. That includes, for example, my ISP, all large Internet exchanges, and anyone tapping into those.
If you set up your device to spin up a new IPv6 address every hour (or even every minute), how will they track you using IPs?
On macOS it's 24h, but it doesn't have to be:
$ sysctl -a | grep temppltime
net.inet6.ip6.temppltime: 86400Minutes or less I guess would defeat tracking, but then what's the point?, it's almost equivalent to NAT it still breaks reverse connectivity? and does it actually work?
It also feels like a workaround for an oversight.
But how would they know it is to the same node?
I have my DSL router-modem reboot every night, and I get all sorts of crazy results for ads: I'm in southern Ontario, as is my ISP, but they service folks in Quebec, and so sometimes I get Youtube ads in French since (per my IP) I'm "in" Quebec.
Similarly with the reboot I get a new /64 prefix delegation (actually /56), so I would hazard to guess if IPv6 starts getting tracked, I'd get the same crazy results.
No one cares about tracking by port. Folks are tracking by IP(v4) address.
I know this first hand because I have my DSL router-modem auto-reboot every night (built-in Asus functionality), and I get all sorts of crazy results for ads: I'm in southern Ontario, as is my ISP, but they service folks in Quebec, and so sometimes I get Youtube ads in French since (per my IP) I'm "in" Quebec.
And given that I have IPv6, most OSes generally use that as a first preference for connectivity, and so my IPv6 address/prefix is "in" Quebec.
And this is even with cookies enabled, which should make tracking by browsing easier (esp. since I get decently-accurate recommendations based on viewing history), but yet I still get French ads because my IPv4/IPv6 address is "in" Quebec.
So I have no idea what people are talking about when they say IPv6 will make tracking easier than IPv4. With RFC 4941 it's a solved problem IMHO and no worse under dual-stack than it is under single-stack.
With IPv6 chances are your ISP has a single large address block, and then they split out parts of that address space to users in ontario and quebec. Unless the ISP publishes details of where they've allocated those blocks, any external site is just guessing.
With legacy IP chances are they have multiple small fragmented blocks, some of which are routed to ontario and some of which are routed to quebec so they're a bit easier to keep track of unless the ISP decides to move them.
Also when you address changes, the legacy address space is probably quite close to full so your previous address is released and probably taken by another customer fairly quickly. The IPv6 space will be much larger, and so recycling occurs far more slowly.
Either way youtube is just guessing, it only knows that the address space belongs to a canadian isp and it has to use the behaviour of whoever used those addresses last. If the previous user set their browser language to french and searched for french sites, youtube will remember that and is more likely to serve you french ads.