North American Network Operators Group
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Re: DNS requests from 209.67.50.203

  • From: Vern Paxson
  • Date: Tue Jan 09 22:00:35 2001 
> 	A good way to reduce this is to turn off recursion for
> people not on your network for your dns server.  This is fairly easy
> to do with bind8/bind9.

The attack isn't via recursive lookups (though recursion could help augment
the attack).  The reflection is in terms of the DNS reply to the purported
requestor (really the victim).  At lbl.gov, none of the requests result in
further lookups from our nameserver.  But the victim still receives the reply
stream, which from a combined large number of name servers is very large.

See my draft paper

	ftp://ftp.ee.lbl.gov/.vp-reflectors.txt

for a discussion of reflector attacks.

		Vern