So how would I even begin to determine where that’s occurring if it’s not 
within our network? We have no control over that to get it removed in any case. 

It sounds like they are blocking remote side not this end(meaning Ask’s or 
others servers, etc. from reaching here) if I’m reading what you wrote 
correctly.

 

George

 

From: Steven Sommars [mailto:[email protected]] 
Sent: Tuesday, July 5, 2016 14:42
To: George R. Kasica <[email protected]>
Subject: Re: [Pool] NTP Status Pool Polling not reaching any of 5 NTP Servers 
but other users/Clients can reach

 

It is port-based blockage by an upstream ISP.

 

On Tue, Jul 5, 2016 at 2:14 PM, Steven Sommars <[email protected] 
<mailto:[email protected]> > wrote:

Assuming these are the servers at 108.76.168.x there may be a source port-based 
blockage.

 

Polling 108.76.168.145 from a client using UDP port=123 works.

Same client, same server, polling using other UDP ports fails.

 

 

 

On Tue, Jul 5, 2016 at 2:01 PM, Steven Sommars <[email protected] 
<mailto:[email protected]> > wrote:

What are the IP addresses?

 

On Tue, Jul 5, 2016 at 1:32 PM, George R. Kasica <[email protected] 
<mailto:[email protected]> > wrote:

Starting on about 6/14/16 at around 0400 local time (Central Daylight Time US 
UTC-6) all 5 of our time servers here can't be reached by the Status polling 
servers apparently. Yes if I put up tcpdump on the Linux hosts and do a packet 
capture on port 123 I can see traffic from many other hosts coming into all 5 
of the systems here and no one is reporting any outages (including where I'm 
employed that used them and monitors them - they were unreachable we'd have 
pages going off within 5-10 minutes).

There is no firewalling that would block by IP or port for port 123 and nothing 
has changed here for set up at that time to cause them to suddenly drop out.

Is there some way I can see what the Pool Status polling is looking like from 
the NTP Pool end to get more of a clue as to why this has suddenly started to 
fail? I've sent email to Ask but haven't yet received a reply.

George
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