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Re: NTP.conf pool vs server




On Thursday 08 June 2017 08:20:51 Darac Marjal wrote:

> On Wed, Jun 07, 2017 at 07:00:52PM -0400, Gene Heskett wrote:
> >On Wednesday 07 June 2017 10:54:26 Darac Marjal wrote:
> >> On Wed, Jun 07, 2017 at 10:35:23AM -0400, Gene Heskett wrote:
> >> >On Wednesday 07 June 2017 08:56:59 ray wrote:
> >> >> I would like to know the correct syntax for entering a server
> >> >> entry for stretch.
> >> >>
> >> >> All the documentation I find says to list the ntp servers in the
> >> >> file as: server 0.XX.pool.ntp.org
> >> >> server 1.XX.pool.ntp.org
> >> >>
> >> >> An example source from 2017 is https://wiki.debian.org/DateTime
> >> >>
> >> >> When I open /etc/ntp.conf on my new stretch installation, I find
> >> >> this format: pool 0.debian.pool.ntp.org iburst
> >> >> pool 1.debian.pool.ntp.org iburst
> >> >>
> >> >> The latest Debian doc says to start the line with 'server'.
> >> >> The latest Debian implementation starts the line with 'pool'.
> >> >>
> >> >> Are these interchangeable?
> >>
> >> As I understand it "server" will do name resolution once and pick
> >> an IP from the result. "pool" will periodically refresh the name
> >> and cycle to a different member of the pool.
> >>
> >> >> Additionally, there is a parameter 'iburst' which I did not find
> >> >> in the Debian docs but found at
> >> >> http://doc.ntp.org/4.1.1/confopt.htm
> >>
> >> Did you install ntp-doc? Did you check there?
> >
> >I haven't gotten around to checking that, its on a raspberry pi3b,
> > which has a fan on its heat sinks, but isn't terribly stable, I've
> > locked it up tight at least a dozen times so far today with my
> > horsing around.
> >
> >But I did appear to get ntp to do its job, by adding "server " in
> > front of the fqdn's in /etc/ntp.conf.
> >
> >[...]
> >
> >Now, if I could just make it use the routers broadcasts. Or could at
> >least prove it is broadcasting. Yes it is, I caught a broadcast at
> >xx.xx.xx.255:
>
> Apparently, the word "broadcastclient" in ntp.conf is what you want:
>
>   broadcastclient
> 	Enable reception of broadcast server messages to any local interface
> 	(type	b address). Ordinarily, upon receiving a broadcast message
> 	for the first time, the broadcast client measures the nominal server
> 	propagation delay using a brief client/server exchange, after which
> 	it continues in listen-only mode. If a nonzero value is specified in
> 	the broadcastdelay command, the value becomes the delay and the
> 	volley is not executed. Note: the novolley option has been
> 	deprecated for future enhancements. Note that, in order to avoid
> 	accidental or malicious disruption in this mode, both the server and
> 	client should operate using symmetric key or public key
> 	authentication as described in the Authentication Options page. Note
> 	that the volley is required with public key authentication in order
> 	to run the Autokey protocol.
>
> This information IS in the ntp.conf manpage, and fairly apparent if
> searching that for the work "broadcast".
>
> >14:16:14.760909 IP coyote.coyote.den.ntp > xx.xx.xx.255.ntp: NTPv4,
> >Broadcast, length 48
> >
> >So it is broadcasting. Now the trick is to make the rest of my
> > machines use it.  Hints & examnples welcomed.
> >
> >And I did install ntp-doc just now. A wee bit more verbose, but still
> > no examples.
> >
Ok, on my test machine I have reinstalled ntp, and edited its .conf file, 
commenting out the server pool, and enabled the noauth and 
broadcastclient options at the bottom of that file.  So we will see in 
due time if its actually using it.  That particular machine has a quite 
low drift clock.

I must say that I am impressed with timedatectl, a systemd clock manager, 
but its not available to a wheezy install.

Thank you.

Cheers, Gene Heskett
-- 
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
Genes Web page <http://geneslinuxbox.net:6309/gene>