DNS hardening, was Re: Dan Kaminsky

Paul Vixie vixie at isc.org
Thu Aug 6 10:16:25 CDT 2009


note, i went off-topic in my previous note, and i'll be answering florian
on [email protected] since it's not operational.  chris's note was operational:

> Date: Thu, 6 Aug 2009 10:18:11 -0400
> From: Christopher Morrow <morrowc.lists at gmail.com>
> 
> awesome, how does that work with devices in the f-root-anycast design?
> (both local hosts in the rack and if I flip from rack to rack) If I send
> along a request to a host which I do not have an association created do I
> get a failure and then re-setup? (inducing further latency)

yes.  so, association setup cost will occur once per route-change event.
note that the f-root-anycast design already hashes by flow within a rack
to keep TCP from failing, so the only route-change events of interest to
this point are in wide area BGP.

> ...: "Do loadbalancers, or loadbalanced deployments, deal with this
> properly?" (loadbalancers like F5, citrix, radware, cisco, etc...)

as far as i know, no loadbalancer understands SCTP today.  if they can be
made to pass SCTP through unmodified and only do their enhanced L4 on UDP
and TCP as they do now, all will be well.  if not then a loadbalancer
upgrade or removal will be nec'y for anyone who wants to deploy SCTP.

it's interesting to me that existing deployments of L4-aware packet level
devices can form a barrier to new kinds of L4.  it's as if the internet is
really just the web, and our networks are TCP/UDP networks not IP networks.




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