[ntp:questions] Reachable and rejected

Steve Kostecke kostecke at ntp.org
Thu Sep 11 01:50:21 UTC 2008

On 2008-09-11, Dave Close <dave at compata.com> wrote:

> Steve Kostecke <kostecke at ntp.org> writes:
>>This ntpd was 41.6 seconds away from the those servers at the time
>>this billboard was taken. That is a very large offset.
>>I would check in the syslog and see if ntpd is having to step the
>>clock. If that is the case you need to fix whatever is causing this
>>massive drift.
> I am having the same problem on SEVENTEEN machines, all of which are
> behind the NAT, and I am NOT having the problem on dozens more which
> are not behind it and are configured identically.

I've run ntpd behind NAT without any special configuration and not had a
problem. Is this NAT box overloaded?

> These are all Fedora machines which run ntpdate automatically as part
> of /etc/init.d/ntpd. The example above is from a machine behind the
> NAT which had been running for more than a week. The drift does not
> surprise me.

Are there any clock reset messages from ntpd in the syslog?

ntpd should be stepping the clock once the offset exceeds 128ms (unless
you've disabled stepping).

BTW: There's often someone awake on #ntp at irc.freenode.net

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

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