[ntp:questions] Bounce attack via pool server

Steve Kostecke kostecke at ntp.org
Mon Dec 23 19:07:10 UTC 2013

On 2013-12-23, Jure Sah <dustwolfy at gmail.com> wrote:

> I am an administrator of a public NTP server joined to "pool.ntp.org".
> Our server has recently been an unwilling party to a NTP UDP based
> bounce attack and have received the report attached below.


> I am using ntpd version 4.2.6p3. I have searched trough the
> www.pool.ntp.org website on the subject and could not find any general
> recommendation for a secure setup, however I might not have been
> looking in the right places.

If you must continue to use NTP <= 4.2.7  add 'noquery' to your
default restrictions.

The current NTP development release includes some anti spoofing
technology and does not require the use of 'noquery'.


NTP Community Supported Documentation is located at

Steve Kostecke <kostecke at ntp.org>
NTP Public Services Project - http://support.ntp.org/

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