spam and CIDR blocks

Jeremiah Kristal jeremiah at
Thu Sep 11 17:22:57 UTC 1997

I know everyone is tired of IP address issues, and even more tired of
spam, but I think this has some operational content.
I'm sure that a good number of network operators have set up null0 routes
for some of the more annoying spam sites, and I'm pretty sure that many
people are sending whole /24s and maybe even larger blocks to null0
because of lack of response by the spam sites.  What is going to happen
when the spammers find that they are unable to reach 30% of their mailing
list because of null0 routes?  The spam sites just renumber into another
network.  Eventually the spam sites, or their upstream provider, will have
to request more addresses from Arin, and this is where we might be able to
gain another tool to fight spam.
All address allocation requests have to be justified, I think that we can
use this to prevent additional allocations to spam sites.  The reasoning
is that spam sites are not using their previously allocated space
efficiently, and have poisoned their existing blocks enough so that even
if they were to give them back to Arin, Arin would be in a very perilous
legal position if they were to re-allocate these block.  Basically, once
an address is associated with spam, it is not going to be globally
reachable until all null0 routes for it are removed.
I'm open to any and all comments, suggestions, corrections, or flames on


More information about the NANOG mailing list