[dunder_cat]

In theory, IPv6 Privacy Extensions (https://datatracker.ietf.org/doc/html/rfc4941) could mitigate this. In practice, I imagine when you bind to `[::]:port`, that also means that the randomized addresses would work for new inbound connections, too. Not sure how long they typically last, but you'd be fighting against the clock at least before a new randomized address.

That being said, on a slightly less common note: it is quite possible to have each individual service running on a /128. E.g. on IPv6 k8s clusters, each pod can have a publicly addressable /128, so activities like NTP would require the container to have an NTP client in it to expose in that way. That'd mitigate a good chunk of information exposure -- that being said, I agree with the larger point about security via obscurity being insufficient.

[aidenn0]

It's a pain in the ass to configure the /128 setup, particularly when your ISP can change your /64 at any point in time.

[jeroenhd]

If you have a shitty ISP that rotates prefixes like it's 2005, hosting anything public is a massive pain already. DDNS works just as well on IPv6, though.

Internally, a ULA will keep things reachable even if you move ISPs. You could even set up a NAT66 setup to translate your changing prefix to your stable ULA so you don't need to update any firewall rules, but that's a pretty terrible workaround for a problem that shouldn't be on you to fix in the first place.