[ntp:questions] Re: NTP Server not responding to clients

Rob MacGregor me at privacy.net
Thu Aug 7 17:37:04 UTC 2003


James wrote:
> Apologies for the verbosity, but it's sort of required for this one, I
> think.
> 
> I've got an NTP server that is not responding to client requests for
> timesync. Here's the scoop:
> 
<---SNIP--->
> As you can see here, this server is able to reach all of its servers
> and its peers just fine:
> -----
> [root at servermachine log]# ntpq -p
>      remote           refid      st t when poll reach   delay   offset
>  jitter
> ==============================================================================
>  LOCAL(0)        LOCAL(0)        10 l    4   64  377    0.000    0.000
>   0.000
>  foo.stratum1.co 0.0.0.0          1 u   16   64  377    0.000    0.000
> 4000.00
>  bar.stratum1.co 0.0.0.0          1 u   60   64  377    0.000    0.000
> 4000.00
>  foo.stratum2.co 0.0.0.0          2 u    1   64  377   71.070   -1.707
>   0.000
>  bar.stratum2.co 0.0.0.0          2 u   28   64  377    0.000    0.000
> 4000.00
>  baz.stratum2.co 0.0.0.0          2 u    -   64    0    0.000    0.000
> 4000.00
> -----

I don't think you're reading that right.  With no refid you've not 
reached it.  You should see at least one line starting with a * to 
indicate sync.

While you may have no firewall rules on that system, either you've 
picked a range of hosts that aren't responding, you've got a routing 
problem or something is filtering 123/UDP.

> *THE PROBLEM*
> Even though servermachine is able to sync with it's servers OK, none
> of our network clients are able to sync with servermachine. As you can
> see from the tcpdump below, the client NTP packets are arriving OK,
> but servermachine just IGNORES them completely. No response is sent to
> the client. No record is left in /var/log/messages.

Because it's not synchronised itself.  Until it's got a sync it won't 
serve time.

-- 
   Rob MacGregor (BOFH)        Oh my God! They killed init! You bastards!
       The light at the end of the tunnel is an oncoming dragon.




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