Re: DNS DoS ???

[Mark Andrews <marka () isc org>]

In message <AE105312-3108-4B0B-8445-7116B84EC428 () arbor net>, "Dobbins, Roland" 
writes:
> On Aug 1, 2011, at 7:42 AM, Mark Andrews wrote:
>
> > Named already takes proper precautions by default.  Recursive service is =
> limited to directly connected networks by default.  The default
> > was first changed in 9.4 (2007) which is about to go end-of-life once the=
>  final wrap up release is done.
>
> This alone isn't enough.  There are quite a few other things folks must do =
> from an architectural and operational standpoint which aren't found in name=
> d.conf.
>
> > The real problem is that many ISP's don't do effective ingress/egress fil=
> tering.
>
> Well, no.  The real problem is a protocol set/implementation which lends it=
> self so readily to spoofing in the first place, followed (as you say) by IS=
> P/endpoint network inattention to anti-spoofing, followed by protocols whic=
> h make use of the eminently-spoofable UDP for a critical service.

And even if DNS/TCP was use by default machines can still get DoS'd
because IP is spoofable.

This one looks like a direct attack on the machine as there are
multiple source addresses rather than a reflector attack unless they
are attempting to attack thousands of sites simultaniously.

> >  This prevents compromised machines impersonating other machines.
>
> Concur, but see above - spoofing is the symptom, not the disease.
>
> -----------------------------------------------------------------------
> Roland Dobbins <rdobbins () arbor net> // <http://www.arbornetworks.com>
>
>               The basis of optimism is sheer terror.
>
>                         -- Oscar Wilde
-- 
Mark Andrews, ISC
1 Seymour St., Dundas Valley, NSW 2117, Australia
PHONE: +61 2 9871 4742                 INTERNET: marka () isc org