North American Network Operators Group

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Re: register.com down sev0?

  • From: Patrick W. Gilmore
  • Date: Thu Oct 26 01:02:30 2006

On Oct 26, 2006, at 12:14 AM, [email protected] wrote:
On 26 Oct 2006, Paul Vixie wrote:

i wonder if that's due to the spam they've been sending out?
Paul, this isn't nanae. Let's not sling accusations like that wildly.
Accusations and objective facts are two separate things.


there is no zone anywhere, including COM, the root zone, or any other,
that is immune from worst-case DDoS. anycast all you want. diversify.
build a name service infrastructure larger than the earth's moon. none
of that will matter as long as OPNs (the scourge of internet robustness)
still exist.
This isn't 2001, and, I will argue that it *is*, in fact, possible to be
protected from a "worst case" ddos, and not at obscene price.
You are mistaken.


However,
even if you argue that point, there's no excuse for not being prepared at
all, and not following the BCP. While we all may be guilty of not having
topologically/geographically diverse DNS - for someone whose core business
is DNS, that's unexcusable.
We agree.


Given that register.com is/was public (I think?) - I wonder what are their
sarbox auditors saying about it now ;)
that's an easy but catty criticism, and baseless. i'm sure that some
way could be found to improve register.com's infrastructure, and i don't
just mean by stopping the spamming they've been doing. but it's not
trivial and in the face of well-tuned worst-case DDoS, nothing will
help.
Well, let's talk about "worst-case ddos". Let's say, 50mpps (I have not
heard of ddos larger that that number). Let's say, you can sink/filter
100kpps on each box (not unreasonable on higher-end box with nsd). That
means, you should be able to filter this attack with ~500 servers,
appropriately place. Say, because you don't know where the attack will
come in, you need 4 times more the estimated number of servers, that's
2000 servers. That's not entirely unreasonable number for a large enough
company.
Even assuming your numbers, which I do not grant, you are still mistaken.

There is no single "appropriately[sic] place" which can absorb 50Mpps. If you meant "appropriately placed" (as in topologically dispersed locations), a well crafted attack could still guarantee _at least_ a partial DoS from an end user PoV.

It is essentially impossible to distinguish end-user requests from (im)properly created DoS packets (especially until BCP38 is widely adopted - i.e. probably never). Since there is no single place - no 13 places - which can withstand a well crafted DoS, you are guaranteed that some users will not be able to reach any of your listed authorities.

This is not speculation, this is fact. All a good provider can do, even with 1000s of server, is minimize the impact of any DoS.

Oh, and putting 2K servers into the "right" places is not a trivial expense, even for a large company. Last time I checked, 10GE pipes were not handed out for free. And you can't just rack these things in mom-and-pop colo saying "well, it has a GigE on the motherboard" when the colo has an OC3 to the 'Net. The Cap- and Op-Ex involved in doing what you suggest properly is large enough to probably be prohibitively expensive for a company like register.com.


I know that the above was just rough back-of-the-envelope, and things are
far more complicated than that, but this discussion does not really belong
to nanog-l.
We disagree. Keeping large name servers running is _absolutely_ a network operations topic. Not only is the defense mostly network based (since the network is the most likely thing to break), network operators are the people who get the phone calls when DNS does break.

--
TTFN,
patrick