RE: [chrony-users] issues syncing between chrony and ntp

["Bauer, Steven J." <Steve.Bauer@xxxxxxxxx>]

> -----Original Message-----
> From: Listengine [mailto:listengine@xxxxxxxxxxxxxxxxx] On Behalf Of
> Miroslav Lichvar
> Sent: Monday, May 09, 2011 12:23 PM
> To: chrony-users@xxxxxxxxxxxxxxxxxxxx
> Subject: Re: [chrony-users] issues syncing between chrony and ntp
> 
> On Mon, May 09, 2011 at 11:40:12AM -0600, Bauer, Steven J. wrote:
> > Software versions:
> > Chrony version 1.25
> > Ntp: 4.2.6p3
> >
> > silver ~ # ntpq -p
> >      remote           refid      st t when poll reach   delay   offset  jitter
> >
> ===================================================================
> ===========
> > ntp.sdsmt.edu   .INIT.          16 u    -   64    0    0.000    0.000   0.000
> > ip-173-201-38-8 198.153.152.52   2 u   18   64    3   66.030    2.070   0.089
> > mail.scottishtr 139.78.135.14    2 u   17   64    3   47.528   -7.556   0.129
> > name1.glorb.com 128.252.19.1     2 u   13   64    3   33.976   -0.975   0.243
> > smtp.envirahost 128.138.188.172  2 u   14   64    3   47.641    1.468   0.119
> >
> >
> > Now, the workaround that I found to get it to work was to add a
> > version 3 on the server line in the ntp.conf as well as specify the
> > ipv4 address of the host running chrony on the host running ntp.
> 
> Interesting, I see no problem with chrony-1.25 as NTP server at stratum 1
> and ntp-4.2.6p3 as a client here.
> 
> Can you see the replies from chrony in tcpdump output on the server and
> the client? My first guess would be a firewall between the two hosts which
> is dropping the NTPv3 packets as they don't match the version in the
> requests.

These hosts are on different segments of the same LAN.  The firewalls are turned off on both of the machines.

I think I have tracked the issue down.  Since the host that has the refclock on it has multiple ip address configured on it.  (two ipv4 address and two ipv6 addresses), the ntp on the remote host was not liking the fact that chrony was sending packs back with a different ip address then what was sent to it as you can see here:  (2607:f558:1000:12::30 and 2607:f558:1000:12::31 are the same machine)

ntp chrony-1.25 # tcpdump  -nns 1514 host 2607:f558:1000:b::30 or host 151.159.1.1  and dst port 123
tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
listening on eth0, link-type EN10MB (Ethernet), capture size 1514 bytes
13:27:40.914394 IP6 2607:f558:1000:b::30.123 > 2607:f558:1000:12::30.123: NTPv4, Client, length 48
13:27:40.914460 IP6 2607:f558:1000:12::31.123 > 2607:f558:1000:b::30.123: NTPv3, Server, length 48
13:28:02.044175 IP 151.159.90.1.123 > 151.159.1.1.123: NTPv3, Client, length 48
13:28:02.044304 IP 151.159.1.1.123 > 151.159.90.1.123: NTPv3, Server, length 48
13:28:47.913024 IP6 2607:f558:1000:b::30.123 > 2607:f558:1000:12::30.123: NTPv4, Client, length 48
13:28:47.913050 IP6 2607:f558:1000:12::31.123 > 2607:f558:1000:b::30.123: NTPv3, Server, length 48
13:29:07.001549 IP 151.159.90.1.123 > 151.159.1.1.123: NTPv3, Client, length 48
13:29:07.001679 IP 151.159.1.1.123 > 151.159.90.1.123: NTPv3, Server, length 48
13:29:51.912563 IP6 2607:f558:1000:b::30.123 > 2607:f558:1000:12::30.123: NTPv4, Client, length 48
13:29:51.912590 IP6 2607:f558:1000:12::31.123 > 2607:f558:1000:b::30.123: NTPv3, Server, length 48

I worked around the issue for now by using the bindaddress configuration to bind to only one ipv4 address and one ipv6 address.  The only thing that this breaks is running chronyc and having it connect to localhost.

Thanks for your help!

Steve


> 
> --
> Miroslav Lichvar
> 
> ---
> To unsubscribe email chrony-users-request@xxxxxxxxxxxxxxxxxxxx
> with "unsubscribe" in the subject.
> For help email chrony-users-request@xxxxxxxxxxxxxxxxxxxx
> with "help" in the subject.
> Trouble?  Email listmaster@xxxxxxxxxxxxxxxxxxxx.


---
To unsubscribe email chrony-users-request@xxxxxxxxxxxxxxxxxxxx
with "unsubscribe" in the subject.
For help email chrony-users-request@xxxxxxxxxxxxxxxxxxxx
with "help" in the subject.
Trouble?  Email listmaster@xxxxxxxxxxxxxxxxxxxx.