D/DoS mitigation hardware/software needed.

Kevin Oberman oberman at es.net
Sun Jan 10 23:13:12 UTC 2010

> From: "Dobbins, Roland" <rdobbins at arbor.net>
> Date: Sun, 10 Jan 2010 21:56:38 +0000
> On Jan 10, 2010, at 11:55 PM, Roger Marquis wrote:
> > The only thing you've said that is being disputed is the the claim
> > that a firewall under a DDoS type of attack will fail before a
> > server under the same type > of attack.
> It's so obvious that well-crafted programmatically-generated attack
> traffic, if nothing else, will crowd out the good traffic that I'm
> just dumbfounded anyone thinks 'proof' of this is needed.  Same thing
> for the fact that horizontally-scaled Web farm (with or without
> reverse caching proxies) will of necessity handle a great deal more
> TCP state than the biggest, firewall made to date.
> >  * because it doesn't correlate with my 22 years of experience in systems
> >  administration and 14 years in netops (including Yahoo netsecops where I
> >  did use IXIAs to compile stats on FreeBSD and Linux packet filtering),
> It doesn't correlate with my 25 years in the industry, a good portion
> of the last 15 years spent handling DDoS after DDoS after DDoS, during
> which the biggest, baddest firewalls choked and died over and over
> again, through multiple generations of said firewalls.
> Again, I was able to take down a hardware-based (for whatever value of
> 'hardware-based' is possible) firewall rated at 2gb/sec with 80kpps of
> traffic.
> > * it doesn't correlate with experience in large networks with
> > multiple geographically disperse data centers where we did use Arbor,
> > Cisco and Juniper equipment,
> It correlates with my experience in large networks with
> geographically-dispersed IDCs with heterogeneous gear.
> > * it doesn't correlate with server and firewall hardware and
> > software designs, and last but not least,
> Which is a non-sequitur.
> > * because you have shown no objective evidence to support the claim.
> I've my own broad subjective experience, and that of several other
> people who've commented on this thread have similar experiences.
> Since you haven't yet acquired this subjective experience, you can
> cause it to happen in a controlled test environment, should you so
> choose.
> > Where then, can we find the results of your testing?
> The testing I did when I worked for the vendor in question is
> proprietary, as you can well surmise.  You're free to do your own
> testing and confirm these assertions for yourself.
> > Nobody has "hurled insults" in this thread other than yourself Roland.
> You accused me of acting in my own pecuniary interest, of trying to
> 'sell' things, *for no reason at all*.
> > We just need some actual statistics.
> If you actually care about the truth of the matter, you're free to
> generate your own.  If you read the RoK/USA DDoS preso to which I
> linked, you see the attack throughput and bandwidth metrics/host, and
> you also see where I noted multiple 'Web Application Firewalls',
> load-balancers, and so-called 'IPS' falling over as a result of those
> attacks.  That gives you a range right there, along with some attack
> traffic characteristics, including average packet size.
> It makes no sense to put a stateful inspection device in front of
> servers, where *every single packet* is unsolicited, and therefore no
> state tracking is even possible in the first place.  Stateless filters
> in hardware capable of mpps do a much better job, without the risk of
> falling over due to state-table exhaustion.

> > Folks who've been unlucky enough to be subjected to significant DDoS
> attacks have run into this issue again and again and again.  Perhaps
> you've simply been lucky; but one can't count on one's luck holding
> forever.

There is a culture that has developed a dogma that firewalls are THE
solution. Be it DDOS or most any other security threat. Like many
dogmas, it is ingrained into so many people that denial is essentially
heresy. People simply "know" that a firewall is essential, so any
contrary argument is obviously bogus or confused and must be denied.

I used to work at the place that probably invented the stateful firewall
and the folks who invented it became the priests of the firewall dogma
and went forth and preached its value. Note that this predates DDOS by
many years and that they did have some valid arguments. But the result
was an army of security "experts" who scowled and marked the audit as
"FAILED" if you did not front EVERYTHING with a firewall. 

I know of one case where an organization bought a firewall and
programmed it to pass everything, just to fix an automatic failure of a
security audit. Oddly, the auditor did not even look at who the firewall
was configured. Simple presence of the box made him happy.

I'm afraid that you are fighting a dogma that will only slowly be
beaten into recognizing reality, but I appreciate your fighting the good
R. Kevin Oberman, Network Engineer
Energy Sciences Network (ESnet)
Ernest O. Lawrence Berkeley National Laboratory (Berkeley Lab)
E-mail: oberman at es.net			Phone: +1 510 486-8634
Key fingerprint:059B 2DDF 031C 9BA3 14A4  EADA 927D EBB3 987B 3751

More information about the NANOG mailing list