NIST IPv6 document

John Levine johnl at
Wed Jan 5 23:01:30 CST 2011

>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.)

John Levine, johnl at, Primary Perpetrator of "The Internet for Dummies",
Please consider the environment before reading this e-mail.

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