[Samba] Time sync not working with Windows 10

me at tdiehl.org me at tdiehl.org
Wed Nov 18 13:41:03 UTC 2020

On Wed, 18 Nov 2020, Mark Foley via samba wrote:

> After our office upgraded to Windows 10, time sync stopped working with the Windows
> workstations. This used to work fine with Windows 7 and still works with linux domain members
> (although that's not surprising).
> The Windows 10 workstations ended up operating off the CMOS clock. We didn't notice this for a long
> time since the CMOS clock drift is slow, but after several months users started noticing up to
> +/-6 minutes difference between their computers and the *real* time.
> Going to 'Date & Time settings > Sync Now' always gives "Time synchronization failed".
> For Windows 7 workstations, several years ago, I followed the advice in
> https://www.meinbergglobal.com/english/info/ntp-w32time.htm which was to do the following on
> the Windows 7 workstations:
> w32tm /config /manualpeerlist:mail,0x8 /syncfromflags:MANUAL
> w32tm /config /update
> Check the configuration:
> w32tm /query /source
> This worked and time was in-sync on the WIN7 computers for many years.  I did this after
> upgrading/installing each Windows 10 workstation during 2019 Q4 and 2020 Q1, but apparently
> that didn't work.
> For the Windows 10 workstations I create the "Time Source" group policy per the instructions in
> https://wiki.samba.org/index.php/Time_Synchronisation. That didn't help either.
> Is it possible that the version of Samba I am using (Version 4.8.2) is too old for Windows 10?
> I could upgrade to 4.13.2, but that is in the "experimental" release of Slackware and may or
> may not install properly.

I do not think 4.8.2 is too old for time sync to work with win 10. However
4.8.2 is EOL as far as samba is concerned.

A couple of weeks ago I was still running 4.8.x on 2 different Ad domains
and time sync was working fine on all of the clients, including the win 10.

I would suggest you have a look at https://wiki.samba.org/index.php/Time_Synchronisation
In particular make sure the symlink points to the correct place.

After we upgraded the DC's to 4.12.x the symlinks got b0rked and that killed time sync
for us. Fixing the symlinks and restarting chronyd and samba fixed the problem.

FWIW, there is no extra configuration required on windows domain members assuming
that the DC's are configured correctly. Just use w32tm /query /source to make sure
the clients are using one of the DC's to sync from. If they are not then there is
a problem with the DC configuration.


Tom			me at tdiehl.org

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