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

Steve Sullivan stevos at nwtime.org
Wed Jan 17 18:26:49 UTC 2018


Hi Mike,

I work for Network Time Foundation in client services. Thanks for bringing
this issue to our attention.

I contacted Pete this morning (his afternoon) and he said he has been in
contact with you on this since our last message. He said there are probably
at most 10 bad units out there flashed with the wrong version. Just to be
sure, I wanted to make sure he was referring to you and not one of the other
9 out there. If not, that unit is replaceable if it is faulty he informed
me. 

I also recommended he get on some our mailing lists and wikis for better
communication with the community.

Pretty cool clocks I must say. I want one :).  Please feel free to reach out
with any questions or concerns you might have.

Thanks,

Steve Sullivan | Client Support & Development
ph. 949-423-6901 | e. stevos at nwtime.org
Network Time Foundation - Home of the NTP Project
We Need Your Support - Please Donate or Join Network Time Foundation Today
www.nwtime.org/donate/   or   http://nwtime.org/membership/why-join/



-----Original Message-----
From: questions [mailto:questions-bounces+stenn=ntp.org at lists.ntp.org] On
Behalf Of Mike S
Sent: Tuesday, January 16, 2018 3:13 PM
To: questions at lists.ntp.org; pool at lists.ntp.org
Cc: Pete Virica
Subject: [ntp:questions] Abusive client, what to do?

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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