Re: [chrony-users] NTP v4 header

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Am 2011-04-29 22:42, schrieb Harald Krammer:
> Am 2011-04-29 12:52, schrieb Miroslav Lichvar:
>> On Thu, Apr 28, 2011 at 10:41:54PM +0200, Harald Krammer wrote:
> [...]
>>> Right now I am fighting again with some NTP implementations. These
>>> returns with NTP v4 answers  instead of ntp v3 answers. Is there
>>> something to consider when I enable ntp v4 answerers in chrony. Any
>>> additional risks?
>> chrony makes a client v3 request and the server replies with a v4
>> packet? I'd say accepting the v4 reply should be safe and will work as
>> expected, but I still haven't found time to study the new RFC 5905 to
>> be sure.
> Exactly and I came to the same opinion.
> Simple ntp servers (also possible with v4) does not seem to work
> together with chrony.  For that I am looking for a solution too.
>>> BTW I merged my few patches to 1.25-pre2 and I did not see any side
>>> effects. Let me know, if I should test something.
>> Are the patches or your git repo publicly available? Maybe some of
>> them should be included?
> Sure, but before I will make my workarounds parameterizable via conf
> settings.

Done, it is public available via
'git clone'
I dropped my old workarounds from 1.23-tree and I will see what will
happen on my tests.

I am not sure if it usable or not. That are small fixes/workarounds to
support substation embedded devices.
BTW, the NTP server from one device is still broken and does not work
properly.  The reason is a failure of test6.

Source: ntp_core.c
  /* Test 6 checks that (i) the remote clock is synchronised (ii) the
     transmit timestamp is not before the time it was synchronized
     (clearly bogus if it is), and (iii) that it was not synchronised
     too long ago

Maybe a next hack is on the way.

I will keep you in touch for any new findings.
Nice greetings,


Harald Krammer

Mobil +43.(0) 664. 130 59 58
Mail: Harald.Krammer (at)

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