Re: [chrony-users] Interop with NTP version 1 and 4 clients

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On Tue, 19 Feb 2013, Benny Lyne Amorsen wrote:

Chrony is working very well as an NTP server (not a stratum 1 of

Chrony works perfectly well as a stratum 1-- just use refclock of say a gps
pps source. What version of chrony are you using?

course). However, certain client requests get no answer and others get a
surprising one.

Some clients use the SNTP protocol, which I believe is also known as NTP
version 1? Those clients do not receive an answer at all. This is
unfortunate since they are SIP phones and have no other way of acquiring

No idea about this. As far as I know sntp uses exactly the same packets as
does full ntpd. get a better app.

Here is the tcpdump of a client indicating NTPv4 but receiving an NTPv3
answer. The client then proceeds to ignore that answer and repeats the

What software is being used by the client?
ntp4 system should accept and ntp3 response, so something is wrong at the
client end.

15:03:55.712716 IP (tos 0x0, ttl 59, id 0, offset 0, flags [DF], proto UDP (17), length 76)
   x.x.x.x.1011 > y.y.y.y.ntp: NTPv4, length 48
	Client, Leap indicator:  (0), Stratum 0 (unspecified), poll 0s, precision 0
	Root Delay: 0.000000, Root dispersion: 0.000000, Reference-ID: (unspec)
	  Reference Timestamp:  0.000000000
	  Originator Timestamp: 0.000000000
	  Receive Timestamp:    0.000000000
	  Transmit Timestamp:   3570271435.694462001 (2013/02/19 15:03:55)
	    Originator - Receive Timestamp:  0.000000000
	    Originator - Transmit Timestamp: 3570271435.694462001 (2013/02/19 15:03:55)
15:03:55.712877 IP (tos 0x0, ttl 64, id 0, offset 0, flags [DF], proto UDP (17), length 76)
   y.y.y.y.ntp > x.x.x.x.1011: NTPv3, length 48
	Server, Leap indicator:  (0), Stratum 4 (secondary reference), poll 0s, precision -19
	Root Delay: 0.009262, Root dispersion: 0.019210, Reference-ID:
	  Reference Timestamp:  3570271416.234727978 (2013/02/19 15:03:36)
	  Originator Timestamp: 3570271435.694462001 (2013/02/19 15:03:55)
	  Receive Timestamp:    3570271435.712715923 (2013/02/19 15:03:55)
	  Transmit Timestamp:   3570271435.712865889 (2013/02/19 15:03:55)
	    Originator - Receive Timestamp:  +0.018253916
	    Originator - Transmit Timestamp: +0.018403917

By the way, what happened to the gmane mailing list subscription? The last mail on gmane is from 2009...

Thanks for a great piece of software!

Thank Richard Curnoe who invented and wrote chrony, and Miroslav Lichvar who
took over when life got too busy for Curnoe and has added a bunch of features
(including handling refclocks)
I agree it is a great piece of software.


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