[ntp:questions] NTP servers not accessible on some networks

David Lord snews at lordynet.org
Wed May 21 09:49:57 UTC 2014

Antonio Marcheselli wrote:
> On 21/05/2014 03:27, E-Mail Sent to this address will be added to the 
> BlackLists wrote:
>> Antonio Marcheselli wrote:
>>> Version is 4.2.4p (yes, I know. It's the same version I've been talking
>>> about and I cannot upgrade it unfortunately).
>>> When running ntpq -p I've got this
>>> xxxxxxx-2:/etc# ntpq -p
>>> remote       refid  st t when poll reach delay offset jitter
>>> ============================================================
>>> .INIT. 16 u    -   64   0   0.000  0.000  0.000
>>> xxxxxxx-2:/etc# ntpdate
>>> 20 May 23:30:11 ntpdate[16690]: no server suitable for 
>>> synchronization found
>>> The same works from other networks.
>> It appears your client quries are not making it to the server,
>>   or answers from the server are not making it back to your client.
>> Seems like an issue with your client PC, PC Firewall, ...,
>>   or client NTP .conf, or LAN Firewall / Router rules,
>>   or ISP  Firewall / Router rules.
>>> If I keep pinging different pools,
>>>   I can find another NTP server which replies.
>> Seems strange, that would imply that the server
>>   (or their ISP) is blocking your client?
> Hi,
> I had another NTP server setup, I stopped the NTP daemon, change the 
> configuration to and restarted it again. 16 is because the 
> server has never been reached. The server can be ping'd of course. And 
> it works as NTP from somewhere else.
> No issues with my side of the network, I end up on a router which I 
> manage and has no special firewall rules in it. And again, other NTP 
> servers do work. This has happened on a few sites around the UK.
> I'll post the ntp.conf later.
> in the meantime thanks for your help!

That has been in the conf of one of my pool servers for years
and it's not often that it's unreachable. I've changed isp
several times, demon, zen and now aaisp.

         remote  st t  poll reach  delay offset jitter
+dir.mcc.ac.uk   2 u   256   377 28.576  3.438  0.135

I might still have a contact at mcc, a member of our computer
club worked there, but I doubt that mcc are blocking you.


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