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Re: DOS attack against DNS?
From: Joe Shen <joe_hznm () yahoo com sg>
Date: Wed, 18 Jan 2006 01:00:36 +0800 (CST)


Last saturday one of our Web server experienced a TCP
SYN attck which make the system down for four hours.
It seems there is not a good solution which could
detect & defend DoS traffic at any time.  

So, to the class ANY queries, should we only filtering
out class any queries on public cache servers ?  To my
understandings, the amplifying result could also be
reached by query type any.

Joe 


--- Alon Tirosh <j0keralpha () gmail com> wrote:

Admitted, i did not notice the type/class
difference. I responded as a knee
jerk reaction, and that is my mistake.

For the second part, the any query type is useful
(when targeted at either
your NS and/or public NS servers) to quickly alert
to issues such as the one
being discussed with GoDaddy and Nectartech right
now on this list.

Pick and/or set up an NS server that is TTL agnostic
(flameArmor: this
system is to be used for disparate up-to-date checks
only, and I know by
spec this is far from foolproof but its saved my ass
a couple times in the
past) and checks disparate roots and its useful for
finding or alerting to
major name system, registrar ,and provider issues
quickly.

Im diverging off-topic, im sure. gnight.

On 1/17/06, william(at)elan.net <william () elan net>
wrote:


Did you notice that it was class "ANY" and not
type "ANY" that Paul noted?
I've never ever heard of it being used
anywhere....

As for ANY query type, what do you think will
happen when you query with
"ANY" to a host in a domain that is not in your
local dns server cache?
And btw if it is in your dns cache, how
predictable do you think such
results are going to be???

On Tue, 17 Jan 2006, Alon Tirosh wrote:

Not true,. the ANY query has mutliple uses for
consolidating multiple
diagnostic queries into a single display, and
also for diversion
monitoring
systems on small domains or groups of same. Not
all of us have the
resources
(or time) of large ISPs behind us.

On 15 Jan 2006 17:27:40 +0000, Paul Vixie
<vixie () vix com> wrote:

client xx.xx.xx.xx#6704: query: z.tn.co.za ANY
ANY +E

class "ANY" has no purpose in the real world,
not even for
debugging.  if
you see it in a query, you can assume malicious
intent.  if you hear it
in
a query, you can safely ignore that query, or
at best, map it to class
"IN".
--
Paul Vixie





        
        
                
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