IPv6 black lists?

Benedikt Stockebrand me at benedikt-stockebrand.de
Wed Mar 10 11:53:06 CET 2010

Hello List,

Dave Taht <d at teklibre.org> writes:

> So this translates out to 2^16*5 = 327680 detected spams to get
> completely blocked for someone that gets a /48 allocation from some
> tunneling provider or another.

Dave is on the right track.  If you work the numbers some more, this
is what you get:

With legacy IPv4, one can maintain a full host-specific IPv4 address
blacklist in 512 MB of memory (using a bitmap with one bit per
address), so this is obviously possible with today's standard

Even if you filtered IPv6 by /48s, that would take 2^16 times as much
memory, or 32 TB.  Filtering at /64 we're at 2 EB (ExaBytes).

Now how long do you expect it for spammers to figure out that once
they take over a machine they should acquire a new address for every
single spam mail they send out?  Once they start to do this, any kind
of address-based blacklist will blow up in your face.

As soon as they hit a home router, they can use the entire /48 or
whatever allocated to the victim by their ISP.

We do have a problem here.



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