> it's not about what I or you care about.
I'm asking whether you care so that I can determine whether it's worth it for me to be talking to you. If you don't care about the benefits of IPv6, then there is no point in me trying to convince you.
I asked again because you said you couldn't respond to something "that long". If you cared, I would expect you to respond to that "long" post. If you don't actually care, then there's no point talking to you about this, so if that's the case, please just say so, so that I can drop this conversation. If you do care about the topic, then please actually read the post and respond to the points if you feel that you have something to say about them.
> It's about what it's useful or not.
IPv6 is useful because it maintains the end-to-end principle in light of the fact that we have so many internet-connected devices. NAT is only useful in situations where address exhaustion would otherwise occur. NAT is not a privacy tool. NAT was not necessary in the dial-up era. NAT is is still not necessary in IPv4 environments with more addresses than devices, such as enterprise/university settings where they have had enough IPv4 addresses since the early days of the Internet that they still don't suffer address exhaustion and thus have no need to use NAT with IPv4.
> Laws require ISP to keep logs because NAT works as a privacy tool.
Those laws don't exist because of NAT. Laws require ISPs to keep equivalent logs even in contexts where NAT is not used at all.
NAT is not a privacy tool. It is not the thing giving you the privacy here. The privacy comes from two things:
1. the pseudonymous nature of the IP address, a property which is just as present without NAT; and
2. the fact that the ISP isn't giving up your identity to anyone and everyone that asks about your IP address. This is a consequence of data protection laws, not of NAT. I said this in the previous post that you said you couldn't respond to because it was "too long".
Let me provide concrete examples to hopefully make the point clear to you: the IP address that I'm sending this post from is 2a02:6b6f:fc22:4c01:211c:b02a:a4f1:266e. My ISP owns the prefix 2a02:6b6x, assigns 2a02:6b6f:fcxx to my neighbourhood, and assigns 2a02:6b6f:fc22:4cxx to my household. However, that household-level assignment is subject to change, and so e.g. tomorrow I may be given 2a02:6b6f:fc48:a9xx instead. As such, the ISP must log the fact that they assigned "22:4c" to me one day, and "48:a9" to me the next day, so that if they are served a warrant asking them to identify which household was the source of packets using address 2a02:6b6f:fc22:4c01:211c:b02a:a4f1:266e, they can actually answer that request.
This is absolutely no different from the case where the adversary's query is instead, "we saw packets coming from address 193.164.21.152 at time X. Which household did these originate from?" My ISP's use of CGNAT means that this address is used by the entire neighbourhood, just like the IPv6 prefix 2a02:6b6f:fc22:4cxx, but this doesn't affect the nature of the query, nor the nature of the information that the adversary has before making the query. The only difference is that with IPv6, the "22:4c" or "48:a9" data can also be seen publicly, but this isn't useful alone in identifying me; it doesn't compromise my privacy in any way.
The exact same is true if the ISP were not using CGNAT for IPv4, but just a single layer of NAT: the adversary can still see the pseudonym of the household in the address of packets that they received, e.g. if the ISP owns 192.0.2.16/28 and delegates 192.0.2.20 to my household, then the adversary sees packets coming from 192.0.2.20, but still doesn't know what household those packets came from until the ISP tells them. Their query to the ISP would also be identical: "we saw packets coming from address 192.0.2.20 at time X. Which household did these originate from?"
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So please, tell me: in your view, what is the actual *practical* difference, if any, when NAT is used vs. when it isn't used? What actual aspect of your privacy is compromised without NAT, but retained or gained with NAT? How is the actual set of possible effects on you any different in either circumstance? You keep saying NAT "works as a privacy tool because you share an address with other people", but *how* do you think that address-sharing actually aids in keeping you private/unidentified compared to no NAT?
Genuinely, I want to know your reasoning here, but you haven't provided any reasoning in light of what I've told you about the nature of networks without NAT, so currently there's literally nothing for me to argue against. You're just saying "but I share a address, therefore I have more privacy." I tell you, "no, that's wrong, and here's why," but then you just repeat, "no, address sharing gives me privacy." That's a completely unfounded statement on it's own. You need to tell me what the tangible privacy benefit that you see actually is, because I don't see any.
