[ntp:questions] better rate limiting against amplification attacks?

A C agcarver+ntp at acarver.net
Thu Jan 9 03:26:37 UTC 2014

On 1/8/2014 18:31, William Unruh wrote:
> On 2014-01-09, A C <agcarver+ntp at acarver.net> wrote:
>> http://arstechnica.com/security/2014/01/dos-attacks-that-took-down-big-game-sites-abused-webs-time-synch-protocol/
>> Here's a live amplification attack at work.
> ....
>>> As I wrote in another post I believe the time is ripe for a sensible
>>> default builtin configuration, which can then be overridden with ntp.conf.
>>> You suggestion in your previous message is very similar to what I
>>> wanted, i.e. the default is to have a pure client using the pool.
>>> As soon as you start writing detailed ntp.conf options I want you to
>>> have the ability to shoot yourself in the foot, if that is your wish.
> But this sounds like it is shooting someone else in the foot. That is
> more serious. Ie, the default is that you should have to work quite hard
> to enable the system to run these amplification attacks (I assume that
> this is using the control system to send control/info packets, rather
> than ntp time protocol packets)

It is unclear (or, more correctly, not publicly documented yet) whether
the attack used the monlist function (outlined in a CERT advisory in
December) or some other method utilizing NTP protocols.  But it was
enough of an attack to cripple the gaming servers for some time.

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