time sync with ntp not working correctly?

[John DeDourek]

Note the column called "reach".  On the server it has 377.
That's the octal (base 8) representation of an 8-bit quantity.
(377 = 11111111 binary).  Periodically a machine running ntp
sends a time query to its configured servers.  When it gets a
reply it shifts a 1 into the right of "reach"; no reply, it
shifts a 0.  Thus on the server, the last eight queries to
its servers got a reply: 11111111.  On the clients 00000000;
that's obviously bad.  So the clients are not getting responses
to their queries.

Two usual problems:
-- Either the queries or the responses to the clients are not
    getting through the network; most commonly firewall issues;
    occasionally network problems like routing; check the latter
    by ping.  The former requires an investigation of the firewall
    setup
-- Bad ntp configuration on the server (refusing to accept queries)
    or on the clients (refusing to accept responses).  You
    unfortunately didn't shows us the ntp configuration on the two
    machines.  Most common problem is that the meaning of "restrict
    notrust" changed between older and newer versions of ntp.  If
    you are reading old guidlines, or have upgraded to the newer
    ntp and used the configuration files from the old one, that
    could be the problem.  Have a quick look at /etc/ntp.conf;
    if the word "notrust" appears on any "restrict" lines, try
    editing it out (saving a copy of the old configuration first).
    If you just copied an old configuration file over the new one
    after upgrading (and happened to save the original installed
    configuration, which I highly recommend), a good procedure would
    be to go back to the ntp.conf installed by the upgrade and edit
    your own server lines in (making changes as appropriate).  In
    any case, we would need to see the configuration files to
    comment further.


Götz Reinicke wrote:
> Hi,
> 
> today I checked the time on some servers and found that they differ by a 
> couple off minutes. Without teh ntpd running a "ntpdate gaugin" syncs 
> the clock.
> 
> All servers are configured using one timeserver using ntp. The clients use
> 
> server 172.17.1.251
> 
> The Relay ntp server uses public servers.
> 
> I've reed the "http://www.tldp.org/HOWTO/TimePrecision-HOWTO/ntp.html" 
> and "ntpq -p" on two clints is:
> 
> remote           refid      st t when poll reach   delay   offset  jitter
> ============================================================================== 
> 
>  gaugin.filmakad .INIT.          16 u    -  128    0    0.000    0.000 
> 4000.00
> 
> on one client:
> 
> remote           refid      st t when poll reach   delay   offset  jitter
> ============================================================================== 
> 
>  gaugin.filmakad 0.0.0.0         16 u    - 1024    0    0.000    0.000 
> 4000.00
> 
> The server:
> 
> remote           refid      st t when poll reach   delay   offset  jitter
> ============================================================================== 
> 
>  LOCAL(0)        LOCAL(0)        10 l   55   64  377    0.000    0.000   
> 0.008
> +nic1.belwue.de  ntp1.belwue.de   2 u  697 1024  377    2.687    0.518 
>  0.343
> +news.belwue.de  nz11.rz.uni-kar  2 u  738 1024  377    2.374   -0.747 
>  0.188
> *dns4.belwue.de  hora.cs.tu-berl  2 u  697 1024  377    2.173   -0.530 
>  0.205
> 
> What could be wrong?
> 
> Regards
> 
> Götz Reinicke