[ntp:questions] running NTP as server only

David Woolley david at ex.djwhome.demon.invalid
Fri Aug 20 23:54:59 UTC 2010


folkert wrote:
> 
> Is it possible to run the NTP daemon only as a server and not as a
> local-clock maintainer?

I don't believe so.

> Reason: I have a virtual machine which gets its time via the vmware
> tooling from the hardware server it is running on. Now this virtual
> machine needs to distribute the time to clients.

But that's not what you mean!

You want the original use of the local clock driver, i.e. to distribute 
a time maintained by non-NTP means.  Please be aware that downstream 
systems will get no warning if that clock is wrong.  Also, the error 
band transmitted will be rather narrow, so, if there is another, more 
stable source of time, clients may reject your source as a false ticker, 
unless you modify the source code to increase the initial root dispersion.

(Incidentally, I don't think this is a sensible thing to do for your 
configuration, but others seem to disagree.

I'm also concerned that NTP might be used to discipline the host, in 
which case you are destroying all the time quality information that NTP 
has carefully calculated!)

Originally, I thought you wanted to have upstream servers without 
disciplining the local clock.  That would be less accurate than allowing 
the local clock to be disciplined, as ntpd would have to run a simulated 
user space clock discipline, rather than the kernel discipline that 
could otherwise be used.




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