[CentOS] Re: ntpd stuck on stratum 16 = not synced

Wed Jan 16 17:32:32 UTC 2008
Tony Mountifield <tony at softins.clara.co.uk>

In article <478E3BC6.3000505 at gmail.com>,
Sean Carolan <scarolan at gmail.com> wrote:
> Maybe there's an ntp expert out there who can help me with this.  I have an NTP server
> serving our local network.  It is 
> set up to use pool.ntp.org servers for it's upstream sync.  ntpq -p reveals that the server
> is stuck on stratum 16, 
> which I understand means "not synced".  The clients are unable to sync with my local server
> because of this.  Here's the 
> output of ntpq -p along with my ntp.conf file:
> 
> [root at ntpserver /root]# ntpq -p
>       remote           refid      st t when poll reach   delay   offset    disp
> ==============================================================================
>   echo.sureproxy. 0.0.0.0         16 u   29   64    0     0.00    0.000 16000.0
>   nist.netservice 0.0.0.0         16 u   19   64    0     0.00    0.000 16000.0
>   ntp.your.org    0.0.0.0         16 u   19   64    0     0.00    0.000 16000.0
>   ntp.pbx.org     0.0.0.0         16 u   19   64    0     0.00    0.000 16000.0

The zeros in the "reach" column indicate that the server has been unable to
receive any packets from the upstream servers.

Is your server inside a firewall? If so, perhaps it is blocking NTP traffic.
You need to have it allow UDP port 123 in both directions. You don't need
port forwarding from outside to in, since all incoming packets will be replies
to outgoing packets.

If it is not inside a firewall, perhaps you have iptables on the server itself
blocking UDP port 123 traffic.

Cheers
Tony
-- 
Tony Mountifield
Work: tony at softins.co.uk - http://www.softins.co.uk
Play: tony at mountifield.org - http://tony.mountifield.org