I have no real first hand knowledge of this, but I have wondered if part of the reluctance of ipv6 is the fact that many of the "powers that be" use ip addresses to identify and group traffic and other activity from multiple devices. They also use ip addresses to block scrapers (both Google and Amazon do this heavily).
With ipv6, an IP address can be completely disposable. You could scrape Google search results all day long and use a different address for each call.
Heck, you could completely proxy search results in real time and create your own search engine, secretly using Google as your backend while injecting your own ads.
If you try to do this at scale you'll find you won't get transit anywhere. Any AS will drop routes from you when Google looks their way. If you think you can ignore them, they'll just threaten upstream. You'll be cut off in hours.
Wouldn't you be bound to a specific subnet dedicated to you? Or how does it work? Can you really just propagate to the world at any time "I am now baba:fefe:..."? Don't backbone routing tables get crazy mad verbose that way?
It would be a random address from a given subnet, yes. Basically the privacy, tracking and banning implications of this are more or less the same as they are with v4+NAT, with the v4 public IP mapping to the v6 subnet.
Note that there's still no way to map a subnet to a person, just like there's no way to map a public v4 address to a person.
Huh, are you implying that with IPv6, the ISP can place multiple unrelated people in the same subnet but not coordinate with them regarding what address from the subnet they use? How does this work from a routing perspective? What if two people pick the same address?
On the other hand, if the ISP ultimately does hand out the address in the subnet (and the end user can merely ask it for a new one), the ISP can retain a record of this, which together with the server-side data can be used to unambiguously deduce who accessed what, whereas the equivalent information in v4+NAT is insufficient without also logging everyone's connection metadata. It would therefore be more appropriate to say the privacy, tracking and banning implications are the same as dynamic IPv4 without NAT, where you can likewise request a new address from your provider at any time.
Normally what happens is: you request a prefix from the ISP (call it a /56, which is 256 subnets of /64 size each), then you pick one /64 from the prefix and use it for your network. Your computers then assign themselves randomly-selected addresses from the /64.
The prefix might be 2001:db8:1:2300::/56, the first network 2001:db8:1:2301::/64, and the machines on that network 2001:db8:1:2301:random:numbers:go:here.
The ISP knows who has which prefix, because they handed them out, but the allocation of IPs inside that prefix is handled entirely by the end-user network. The ISP isn't involved in it, so they have no idea which IP is which computer.
With NAT the LAN-side IPs are hidden from the ISP. In v6 the ISP can see the LAN part of the address, but without any way to identify which machine is using which IP that doesn't give them any extra information. All they get is the prefix and a random number. Computers typically change the random number on a regular basis too so you can't even do any long-term analysis on it.
Oh, I see where the misunderstanding is. In cases like the one addressed in Belgium, the ISP actually assigns the same outward-facing IP address to multiple unrelated customers, and NAT is performed on the ISP side. Somebody who has merely recorded the IP address that made a request therefore has no legal way of determining that it came from you or someone close to you, rather than a number of complete strangers who were assigned the same address, unless the ISP maintains a record of what connections were mapped.
As far as I know, in the US this is mostly common for mobile providers. If we are just talking about a NAT in your home LAN, this won't help you for privacy/security: law enforcement and whoever else still know that the IP address is yours.
That would normally be called CGNAT. Yes, that does change things somewhat... except what's actually going to happen is that people will record the port number and the time as well as the IP, and the ISP is going to record every single connection you make in a big database, and then bill you for the privilege of doing it. Law enforcement will still be able to identify you, now your ISP has a record of everything you've done, and you're still dealing with the headaches of NAT all the time. Doesn't really seem worth it to me.
As far as I know, several court cases in Germany have confirmed[1] that the mapping of dynamically assigned IP to customer identity may only be stored for 7 days. I imagine the same upper bound, or an even tighter one, applies to the records you are talking about.
Around here I'd expect something more like a 7 year minimum to be more likely...
Limiting the timeframe does improve the costs and the privacy impact, but the ISP will still need to build and run all of the logging infrastructure, and the end result is that you'll still be identifiable.
With ipv6, an IP address can be completely disposable. You could scrape Google search results all day long and use a different address for each call.
Heck, you could completely proxy search results in real time and create your own search engine, secretly using Google as your backend while injecting your own ads.