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Message-ID: <53647EE2.2010305@bluerosetech.com>
Date: Fri, 02 May 2014 22:30:10 -0700
From: Darren Pilgrim <list_freebsd@bluerosetech.com>
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To: d@delphij.net, "Ronald F. Guilmette" <rfg@tristatelogic.com>, 
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Subject: Re: FreeBSD Security Advisory FreeBSD-SA-14:08.tcp
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On 5/2/2014 1:05 PM, Xin Li wrote:
> Blocking inbound IP fragments is generally a good safety measure, but
> keep in mind that doing so could break certain applications that do
> require it (e.g. don't be surprised if some user behind several layers
> of firewalls see blank pages from your website) and that needs to be
> taken into consideration.

They won't even get to the site in the first place.  With EDNS, a very 
large DNS response over UDP is possible.  On the wire, it's a single 
large UDP packet fragmented at the IP level.  If you block fragments, 
you'll only get the first part of the UDP packet.  Using a validating 
resolver pretty much guarantees you'll see such UDP packets regularly.