[ntp:questions] Re: Passive client?

Maarten Wiltink maarten at kittensandcats.net
Thu May 25 14:54:47 UTC 2006


"Richard B. Gilbert" <rgilbert88 at comcast.net> wrote in message
news:4_SdnUu8gIks7OnZnZ2dnUVZ_tmdnZ2d at comcast.com...
> Collins wrote:

>> Is it possible to configure a client so that it never attempts any
>> communication with a server but simply monitors a multicast group for
>> updates?  If so how?
>>
>> A possibly related question: what is the behavior of ntpd if it is
>> started with a configuration file which specifies no servers?

> I don't believe it's possible.  Ntpd needs to exchange packets even
> when acting as a broadcast or multicast client.  That is necessary
> to establish a value for the round trip packet delay.  Once the
> client determines the delay, it will shut up and listen.

As Terje said, 'novolley' disables that. Unfortunately, at least at
some point in the past, it only worked for broadcast associations.

I still don't know if and how you can configure a fixed value for the
latency.


> I've never tried starting ntpd without any servers.  It's just one
> of those things that never occurred to me as a sane or useful thing
> to do.  If the designers considered the case at all, they probably
> had the code exit; there is nothing useful that it could do without
> at least one server.  If, OTOH, ntpd loses contact with all its
> servers it should continue to discipline the local clock using the
> last available data.

The daemon can start without associations, in fact it does. And it
will read the drift file.

Groetjes,
Maarten Wiltink





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