North American Network Operators Group
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Re: blocking unallocated subnets

  • From: Rob Thomas
  • Date: Fri Dec 02 15:07:00 2005 
Hi, John.

] I work for a large email provider and we've run into trouble
] delivering mail to certain sites after bringing up new servers in a
] recently allocated subnet of 72/8.  Apparently, some folks decided it
] would be a good policy to protect their nameservers from ddos attacks
] to silently drop requests from unallocated subnets.  So they obtained
] a list of subnets at some point in the past, deployed it and then
] never updated it.

This is why we recommend to those who filter unallocated and bogon
space to keep current with lists such as the sundry formats found
here:

   <http://www.cymru.com/Bogons/>

Another option is to automate the updates and leave the hard work
to us!  :)  Consider peering with the Bogon route-servers, located
throughout the globe thanks to the kind donation of hosting from
several folks.

   <http://www.cymru.com/BGP/bogon-rs.html>

Thanks,
Rob.
-- 
Rob Thomas
Team Cymru
http://www.cymru.com/
ASSERT(coffee != empty);