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Re: NTP.conf pool vs server




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.

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>


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