nanog mailing list archives

Re: misunderstanding scale


From: Owen DeLong <owen () delong com>
Date: Tue, 25 Mar 2014 22:31:25 -0700

IPv6 adds an entirely new aspect to it.

Well, if you mean the entirely new aspect is a list of hex addresses instead of dotted decimal addresses I guess so.  
I personally would rather have a list of actual end system addresses than a list of addresses that represent a mail 
server and several thousand other innocent devices behind a NAT.  Might be easier to tell the system owner which 
system is compromised than to call a large company and tell them one of their systems is compromised.  It would also 
be nice to be able to allow legitimate email to a business partner while blocking his compromised system only.  


I thin the new dimension is that a spammer today who manages to snag a /8 has 16.7 million addresses to play with. Even 
if he forces you to add each and every one to your list, that’s a few megabytes for a VERY large IPv4 block.

OTOH, a spammer with a single /64, pretty much the absolute minimum IPv6 block, has more than 18 quintillion addresses 
and there’s not a computer on the planet with enough memory (or probably not even enough disk space) to store that 
block list.

Sometimes scale is everything. host-based reputation lists scale easily to 3.2 billion host addresses. IPv6, not so 
easily.

Owen



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