[ntp:questions] multiple instances of NTP on different interfaces

unruh unruh at invalid.ca
Wed Mar 6 00:25:30 UTC 2013


On 2013-03-05, Rob <nomail at example.com> wrote:
> unruh <unruh at invalid.ca> wrote:
>> On 2013-03-05, Rob <nomail at example.com> wrote:
>>> David Woolley <david at ex.djwhome.demon.invalid> wrote:
>>>> Abu Abdullah wrote:
>>>>
>>>>> 
>>>>> Does this mean ntpd is not supposed to be run in parallel? Is there any
>>>>
>>>> It is not seen as something anyone would want to do.
>>>
>>> I could understand why someone would want to run one instance that
>>> controls the clock, and another instance that only serves time to
>>> clients on the (inter)net and cannot control the clock.
>>
>> You could? I cannot. ntpd both controls the clock and serves time. Why
>> would you want to split those?
>
> Because the users of the clock service may be able to disturb that
> service, e.g. by overloading it, by making it crash sending it invalid
> requests, etc.  Some people may consider the service to keep their own
> clock correct to be more important than the service to tell time to
> others.
>
> Seeing the reply that the OP posted in the meantime, I was not too far
> off.  He wants a separation between the internal use of NTP to sync
> the local and other important systems, from the service to give time
> to others.
>
> I think it is a reasonable wish.  Certainly not something that nobody
> would want to do.

Well, I would just put the outside service onto some inconsequential
machine at a higher stratum and have it read time from an inside server. 
If you are worried about someone crashing it, you do not want it to be
on the same machine, since that crash is liable not to crash ntpd but
the whole machine anyway. 

Ie do not run them on the same machine if that is your worry.



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