In general, no. All operating systems default to using random host bits in SLAAC addresses, each bootup (or change of network interface) will instantiate a new address.
More than that though, IP addresses in both v4 and v6 varieties are unreliable sources for tracking and basically no actor you'd want to guard against depends on them anyway. With mobile phones being common, your public addresses are changing all the time anyway. On IPv4, CGNAT is becoming increasingly more common so that you might share a public IPv4 address with thousands of other people at the same time.
A counterpoint is that by cycling through IPv6 addresses no one can ever tell who is who by addresses alone. Okay, they could probably tell from the IPv6 prefix because the entire company/household shares it, but people used to ("use to" if you live in a Western country, probably) share the same public IPv4 address too so I find that point rather moot.
Another very strong counterpoint to this is that, you can't really build a truly-P2P network nor self-host a service on Internet, when everyone is behind CGNAT. At some point, as IPv4 resources get scarcer, only corporates will have the ability to host services on the Internet, and I don't think it is in their interests to host Tor nodes, for example...
> Which is an advantage from an anti-tracking perspective
Depends. It makes it harder for someone outside your ISP to track you, but it makes it easier for your ISP to track you, and harder for them to justify not keeping logs of where you've connected to (since that data is necessary for their CGNAT system to work).
You get a new IPv6 address very quickly (mostly every day or every week). That makes tracking difficult too. While the prefix is mostly stable, that is akin to the public CGNAT address.
I mean people are just going to log into their gmail account in their chrome browser and it doesn’t matter if you change IP’s every single minute, that identity isn’t changing as often and the relevant information Google wants will be tracked.
SLACC dynamic address are basically the same as IPv4 NAT from this perspective. Everyone who cares has tables of the prefix size assigned to customers in various providers' IP space.
> All operating systems default to using random host bits in SLAAC addresses, each bootup (or change of network interface) will instantiate a new address.
Great, so I can't connect my laptop to my desktop across reboots without setting up some internal dns?
On Windows, you will see a "temporary IPv6 address" and "IPv6 address" on your network configuration screen. On Linux, you will see an IPv6 address without a temporary tag, and an IPv6 address with one, when you run the command `ip address`:
inet6 2406:xxxx:xxxx:xxxx:xxxx:xxxx:xxxx:62c9/64 scope global temporary dynamic
inet6 2406:xxxx:xxxx:xxxx:xxxx:xxxx:xxxx:a31c/64 scope global dynamic mngtmpaddr noprefixroute
Temporary IPv6 address changes every now and then, but your stable IPv6 address will never change unless your ISP changes your prefix, you change your network, or your network card entirely.
When you are browsing the internet, the OS will use the temporary address for outgoing connections (unless the application forces stable addressing). But when you are hosting a service, you give your users (in this case, your laptop) the stable address.
No, IPv6 devices are typically assigned both a permanent IPv6 address and a temporary one. When using the internet, it uses the temporary address for privacy reasons.
If you want to hand configure your network, set up DHCP and disable SLACC. I wouldn't recommend it, because it just makes life harder, but you can do it.
Even better though, hostname resolution works just fine on link local addresses (fe80::/16), you needn't care about public addresses to communicate on a LAN. Or hell, you're on a LAN, keep configuring IPv4 they way you always have.
With limited IPv4, many places have dynamic IPv4 in a way or another, or have IPv4 behind some sort of NAT, so the actual IP of the accessing device may be hidden, or are private addresses. Anyway, that doesn't mean that i.e. your ISP couldn't be asked what person was using certain dynamic IP at some time.
With IPv6 it depends on implementation. Your device may have a public IPv6 address, persistent or not, and you don't need to be behind some sort of NAT (unless it is something to access ipv4 addresses), so if a lot of those conditions apply you might be tracked.
But there is a lot of conditionals in both sides, and the elephant in the room is that you are tracked for more things than just your IP address.
It can in the near term, as each endpoint has a unique public identifier instead of being mixed with multiple endpoints behind a NAT gateway, but less so over the long term, as privacy addresses are typically rotated at least daily.
Of course, all of this needs to be included in a broader discussion around myriad vectors of tracking and fingerprinting to arrive at a meaningful conclusion.
You can be tracked with either, but IPv6 is not functionally worse than IPv4 in that regard. You could argue that IPv6 is less anonymous than CGNAT, but CGNATs usually have to keep detailed logs, so that balances out.
All the tricks for anonymizing IPv4 (VPN, NAT, Tor, etc.) are equally feasible on IPv6.
