[janosdebugs]

That may be true mathematically, but there are no guarantees that a small provider won't end up having only a single /64, which would likely be the default unit of range-based blocking. Yes, it "shouldn't" happen.

[dfox]

You cannot reasonably build an ISP network with single /64. RIPE assigns /32s to LIRs and LIRs are supposed to assign /48s downstream (which is somewhat wasteful for most of kinds of mass-market customers, so you get things like /56s and /60s).

[janosdebugs]

As I said, "should". In some places there will be enough people in the chain that won't be bothered to go to the LIR directly. Think small rural ISPs in small countries.

[hot_gril]

What if it uses NAT v6 :D

[hot_gril]

Right. It's analogous to how blocking an ipv4 is unfair to smaller providers using cgnat. But if someone wants to connect to your server, you might want them to have skin in the game.

[janosdebugs]

The provider doesn't care, the owner of the server who needs to log in from their home internet at 2AM in an emergency cares. Bad actors have access to botnets, the server admin doesn't.

[Sanzig]

Well, allocating anything smaller than a /64 to a customer breaks SLAAC, so even a really small provider wouldn't do that as it would completely bork their customers' networks. Yes, DHCPv6 technically exists as an alternative to SLAAC, but some operating systems (most notably Android) don't support it it all.

[tsimionescu]

There are plenty of ISPs that assign /64s and even smaller subnet to their customers. There are even ISPs that assign a single /128, IPv4 style.