This bug was reported in our internal bug tracker and assigned to me.
 At first, I disagreed that it was a bug but surprisingly there exist users
who are running into this problem. We are making images for using in
Vmware, and we don't know beforehand what time zone uses the client who
installed image. So we are assuming that BIOS time is in UTC. But VMware
hypervisor sets BIOS time to the local time! It can't be changed judging by
googling results and reading several discussions on the subject.  The
operating system starts up in Moscow (UTC +3), then interfaces are being
brought up by usage of dhclient, then goes NTP synchronization - and time
goes back on three hours. With short leases, it leads to the bringing
ifaces down.

  I've made two solutions with gettimeofday() replacements: using
LD_PRELOAD and other solution using direct compile-in replacements. Both of
the solutions were quickly approved by our corporative code review. I've
even put the somewhat simpler LD_PRELOAD hack on public githup
<https://github.com/kunschikov/ld_preload_gettimeofday>.  So it is not a
problem for now, but it will be cool to know that someday it will be
properly fixed in some future version.

 Now I am going to nicely blame our support QA now by rephrasing your words
that from 1993 there wasn't any person except them who bumped into this
problem.

2017-07-11 18:49 GMT+03:00 Francis Dupont via RT <dhcp-confidential@isc.org>
:

> On Tue Jul 11 15:06:25 2017, kunschikov@gmail.com wrote:
> > Again can be easily checked by usage of `strace`.
>
> => hum, it seems your solution (change the gettimeofday
> clock for a monotonic one) is the only one which does not
> require some redesign/recode...
> Two notes:
>  - I have a tool for DNS which increases exponentially
>   the clock speed. It is used to check re-signing & co.
>   It is based on redirection of the gettimeofday system call
>   in a very similar way...
>  - unfortunately your solution won't work between reboots
>   so you have to remove the client lease file to reset the
>   state (this file is used at startup as an optimization and
>   is not critical at all, BTW many clients have no stable
>   storage so should not depend on it).
>
>