Still, the idea that "nobody will scan a /64" reminds me of the days when 640K ought to be enough for anybody, ...
We really need to wrap our heads around the orders of magnitude involved here. If you could scan an address every nanosecond, which I think is a reasonable upper bound what with the speed of light and all, it would still take 500 years to scan a /64. Enumerating all the addresses will never be practical. But there's plenty of damage one can do with a much less than thorough enumeration.
And the "depth" of infrastructure at which you can decide the traffic is bogus is much greater with IPv6. Most will end up on the target network anyway, no?
I get the impression that we're just beginning to figure out all the ways that bad things can happen when friends or foes start using all those addresses. For example, over in the IRTF ASRG list we're arguing about what to do with IP based blacklists and whitelists, since spammers could easily use a unique IP address for every message they ever send. (Please don't argue about that particular issue here, but feel free to do so in the ASRG.) Regards, John Levine, johnl@iecc.com, Primary Perpetrator of "The Internet for Dummies", Please consider the environment before reading this e-mail. http://jl.ly