[ntp:questions] Ntpd and changing IP addresses

Juliusz Chroboczek Juliusz.Chroboczek at pps.jussieu.fr
Wed Oct 10 19:26:35 UTC 2007

>>> Is there a way to tickle the ntp daemon so that it notices that
>>> the set of IP addresses has changed?  Even better, is it possible
>>> to have ntpd daemon deal automatically with address changes?

>> What version of ntpd are you running?

4.2.4.  (It labels itself as ``4.2.4-1'', it's an OpenWRT package.)

>> The stable release 4.2.4 supports dynamic address changes of the
>> interfaces. I believe that the default check interval is currently
>> every 10 minutes but can be changed on the command line.

> It is 5 minutes.

Hmm, that doesn't fit what I've observed.  I guess I should look at it
again, but I had come to the conclusion that once a server is
discarded, it never comes back.

Still, none of this changes my initial query.  I can easily send
a signal to the NTP daemon when IPs change to speed things up; but
there's nothing in NTP's docs that indicates that such functionality
is supported.

> And it is 2 seconds after the change if the platform supports
> routing sockets.

Does that include Linux's rt_netlink?  (Which is roughly equivalent to
BSD routing sockets, but even more messy.)

> If you run 4.2.4(pX) you can add the keyword "dynamic" to the server and
> peer configuration lines.

Thanks, I'll look into that.


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