[ntp:questions] Re: "Listen on" semantics

Danny Mayer mayer at ntp.isc.org
Sun Sep 24 03:49:25 UTC 2006

Luc Pardon wrote:
>    To make it [clearer|more confusing] : currently, the (x)ntpd "time
> client" uses a "socket server" (listening) to receive its time info,
> i.e. it operates in async mode. I would like to see it use a regular
> "socket client" in synchroneous mode instead.

That won't happen with ntpd. That means you are blocking sitting there
waiting for something to happen. Nothing else can be done. ntpd doesn't
just listen, it also sends out packets.

>     Exactly. I don't care too much how the client and server are
> implemented, in separate processes or in one single process, although
> personally I'd go for separate if possible (KISS and security). But if
> they are in a single process, I'd do want to be able to switch the
> logical components (client, server, peer) on or off in the config file
> to suit my needs.

We call those restrict statements. It's already in the code and does
exactly what you want.

>> The introduction of a 'client only' mode for NTP (not SNTP) would make
>> many people happy already. That could use ports in such a manner that
>> time service does not automatically become available from the machine,
>> and could try not to get in the way of a separate simple NTP time server.

You can do that today.

>     It certainly would make _me_ happy. What I miss in OpenNTPD is not
> so much the reduced precision as the lack of ntpq.
>    In any case, I believe that "my" setup, i.e an stratum 3 server for
> an internal network, is a typical setup. It's Not Good to force all
> these admins to choose between better time and better security if they
> can have both.

You get that today with ntpd. Nothing else out there provides both.


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