[ntp:questions] Abusive client, what to do?

Mike S mikes at flatsurface.com
Tue Jan 16 23:13:13 UTC 2018


I recently built a Nixie tube clock with a kit purchased from
http://www.pvelectronics.co.uk/ . They also have an "WiFi NTP Sync
Device" which can be configured on WiFi to get time from an ntp server
to keep the clock in sync. ("141 Units in Stock")

After setting it up, I immediately noticed it was polling the ntp server
EVERY 6 SECONDS. This, to keep a clock with a 1 second resolution in sync.

But, not only does the WiFi NTP Sync Device normally poll every 6
seconds, but it also does a DNS lookup each time it polls. While it's
good to do a fresh DNS lookup on occasion, it's bad to do so for every poll.

The canonical implementation of ntp, has a default setting for
restricting incoming polls to an average of 8 seconds
(https://www.eecis.udel.edu/~mills/ntp/html/accopt.html#discard). Many
ntp servers send a "Kiss-o'-Death" packet when they find a client
polling too often
(https://www.eecis.udel.edu/~mills/ntp/html/rate.html#kiss).

The PV electronics NTP thing does exactly the opposite of what it should
do - instead of slowing down, it immediately does another DNS lookup and
then does another NTP poll. So when it should be slowing down from its
abusive 6 second polls, it actually speeds up to several polls per
second, with a DNS lookup preceding each. Ouch!

6 second polls are, of course, abusive. They're also in direct violation
of the ToS for the ntp pool servers, which PV Electronics suggests using.

They were informed of these issues over 3 weeks ago (Pete Virica
<pete at pvelectronics.co.uk>), and nothing has been done to address the
issues. I don't know if anyone on the list has contact with Pete, or if
anyone is in a position to push them to fix their stuff, but at this
point I don't see any way to get them to react other than a good old
public shaming.

---
Mike


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