[ntp:questions] ISP bloked port 123

Rob nomail at example.com
Wed Sep 18 08:20:36 UTC 2013

Bert Gøtterup Petersen <BUP at bang-olufsen.dk> wrote:
> David,
> I understand that a Raspberry-Pi would do the trick, and I am sure that would work  for everyone reading this.
> However, to our customers and installers this would be rather invasive. They are buying/installing a TV not an IT system..
> Our accuracy requirement are not impressive, merely to allow the product to talk to our cloud service (UTC +-5min).
> Our assumption is that some ISP block the port to prevent their customers from running a public NTP server.
> At the moment our best bet seem to be using 'ntpdate' on a different port at regular intervals. From a SW perspective, this is not nice nor elegant, but it would do the trick...
> Cheers
> Bert

Usually a TV gets the time from the DVB or Teletext data stream.
It does not always work correctly due to lazy TV station operators, but
at least it does not require internet.

When you are considering using NTP, please do not use the NTP pool
without througly reading and understanding everything that is written
on the website, including the requirement of registering your own
manufacturer subdomain, the use of a reasonable polling interval, and
the requirement of NOT polling at a fixed time like the top of the
hour or the top of the minute.

Of course, when you setup your own NTP server specificially for your
own customers those restrictions to not apply.

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