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To subscribe or unsubscribe via the World Wide Web, visit https://lists.isc.org/mailman/listinfo/dhcp-users or, via email, send a message with subject or body 'help' to dhcp-users-requ...@lists.isc.org You can reach the person managing the list at dhcp-users-ow...@lists.isc.org When replying, please edit your Subject line so it is more specific than "Re: Contents of dhcp-users digest..." Today's Topics: 1. Re: DHCP client protocol timing affected by NTP time change (Klemen Sladic) ---------------------------------------------------------------------- Message: 1 Date: Thu, 10 Aug 2017 10:21:51 +1200 From: Klemen Sladic <gostur...@gmail.com> To: Users of ISC DHCP <dhcp-users@lists.isc.org> Subject: Re: DHCP client protocol timing affected by NTP time change Message-ID: <CAN6eUaGV=cpdm+vbbsbl96m-9l_jf-x18wsuhlurf6xlz61...@mail.gmail.com> Content-Type: text/plain; charset="utf-8" Hi. Thank you all for your comments and suggestions. I will have to spend some more time to see which solution should I apply. For now, a temporary one is to restart the DHCP client on date/time change. This is far from how it should be done, I think, but will fix the problem at the moment. I have to find out how this NTP-related stuff works on "real" systems. RegK On Wed, Aug 9, 2017 at 1:52 AM, Bob Harold <rharo...@umich.edu> wrote: > > On Tue, Aug 8, 2017 at 9:48 AM, Mike <the.li...@mgm51.com> wrote: > >> On 8/8/2017 8:39 AM, Eugene Grosbein wrote: >> > 08.08.2017 19:29, Pavel Zhukov wrote: >> > >> >>>> I am experiencing an interesting problem with DHCP client timeouts. >> >>>> When the system boots up it set its date/time, starts DHCP client >> and NTP client. >> >>>> Only after the DHCP client interface is configured, the NTP client >> is able to access >> >>>> the NTP server. >> >>>> In my case, when NTP client adjusts the date/time it is set 12 hours >> back because >> >>>> of different time zone. >> >>> >> >>> That's plain wrong and that's a root of your problem. >> >>> In no way a time zone difference should affect NTP time and kernel >> >>> time. >> >> Unfortunately it's not. Some systems keep local time in RTC. >> > >> > They are asking for troubles. They should not do that. >> > dhcp code is not only one that would misbehave due to kernel time step >> back. >> > >> >> Besides of that there are systems without RTC at all >> > >> > Yes, and I have such system. They init kernel time with some constant >> in the past >> > at the boot time (like, 1 Jan 2000) and step time forward, not back. >> > So, they don't have this problem. >> >> >> Perhaps a workaround in the OP's instance would be to run the date >> command early in the boot cycle (before DHCP and NTP start) and set the >> system time to some early value. Then, when ntp finally starts up it >> will be a guaranteed jump forward. >> > > Good idea. As an alternative, add a "dhcp renew" after ntp updates the > time. I think that might be safer. Would that work? > > -- > Bob Harold > > > _______________________________________________ > dhcp-users mailing list > dhcp-users@lists.isc.org > https://lists.isc.org/mailman/listinfo/dhcp-users > -------------- next part -------------- An HTML attachment was scrubbed... URL: <https://lists.isc.org/pipermail/dhcp-users/attachments/20170810/02328e66/attachment-0001.html> ------------------------------ Subject: Digest Footer _______________________________________________ dhcp-users mailing list dhcp-users@lists.isc.org https://lists.isc.org/mailman/listinfo/dhcp-users ------------------------------ End of dhcp-users Digest, Vol 106, Issue 8 ******************************************