[ntp:questions] Problem with date since a few hours

David Woolley david at djwhome.demon.co.uk
Sat Dec 2 19:34:37 UTC 2006

In article <F5kch.10582$k74.4900 at text.news.blueyonder.co.uk>,
David J Taylor <david-taylor at blueyonder.co.not-this-bit.nor-this-part.uk> wrote:
> Fabrice wrote:
> >> Richard B. Gilbert wrote:
> []
> >>> FWIW NTP uses UDP rather than TCP!
> > According to netdate man page, both protocols can be used.

> Then the manual is wrong in at least one respect, and perhaps how many 
> others?

The man page is correct, but has nothing to do with NTP; it refers
to the protocol on port 37, whereas NTP is on port 123.  Being in
pool.ntp.org doesn't constitute permission to use the port 37 protocol.
(On some systems, the equivalent of netdate is called rdate.)

Almost certainly what happened is that the random selection of servers 
selected one that particularly disliked unauthorised accesses on port 37
and deliberately served an incorrect time to such clients to try and
dissuade them.  Subsequently it selected a server that wasn't so aggressive
in defending itself against port 37 attacks.

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