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Today's Topics:
1. Re: Regarding the dhcp lease time (Murali Krishna)
2. Re: Regarding the dhcp lease time (Niall O'Reilly)
3. Re: Regarding the dhcp lease time (Bruce Hudson)
4. Re: Regarding the dhcp lease time (Murali Krishna)
5. Re: Regarding the dhcp lease time (Simon Hobson)
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Message: 1
Date: Mon, 13 May 2019 20:46:46 +0530
From: Murali Krishna <muralikris...@gmail.com>
To: Users of ISC DHCP <dhcp-users@lists.isc.org>
Subject: Re: Regarding the dhcp lease time
Message-ID:
<cakhvxa3rqtacoo5rhvvvho04jzakzlqdoaow-fn5y+vmba9...@mail.gmail.com>
Content-Type: text/plain; charset="utf-8"
Hi,
I agree to your comments that rather than the usecase this is a testcase.
The same test case is working without any issues, when the below versions
are available on server and client respectively.
version available on server and client: 4.2.1-P1
But the same testcase is not working when we have the below versions.
version on server: 4.3.6
version on client: 4.2.1-P1
Apart from that, the other clarification which i would like to get
clarified from the experts is that how the server acts to the DHCP requests
from the clients in a situation where the time stamps are completely
different. From the conf file server should acknowledge the respective
seconds of the leasetime(as mentioned in conf file) irrespective of the
timestamps. This is not happening in this scenario where server is offering
a huge lease value.
In the current scenario client requested for the respective lease for the
time duration as mentioned in the conf file.
Here is the sequence of flow it happened:
1. Client initiates DHCP Request for 3600s(1hr)
2. Server acknowledges(DHCP Ack) with lease time:(158253440s) 1831 days, 15
hours, 17 minutes, 20 seconds
How the server is calculating the lease time which is not the one defined
as per the conf file.
Thanks & Regards,
Muralikrishna
On Fri, May 10, 2019 at 9:55 PM Simon Hobson <dh...@thehobsons.co.uk> wrote:
> Rob Janssen <r...@ision.nl.eu.org> wrote:
>
> > I have seen such postings many times on NTP lists and groups, where a
> "local team" wants to validate the operation of the NTP service and decides
> to write a testplan similar to this:
> >
> > - setup an isolated local network with a client and a server
> > ...
> > - manually change the clock of the client (or the server) by several
> years ...
> >
> > When that does not work out, they come and ask why.
>
> Or come here and ask why the DHCP service is "broken" !
>
>
> > Having a LAN address of 169.254.x.x is not that uncommon in such test
> environments.
>
> Which is still not valid for a DHCP server - common or not.
>
>
> We'll just have to wait for the OP to come back with an alternative
> narrative ;-)
>
> _______________________________________________
> dhcp-users mailing list
> dhcp-users@lists.isc.org
> https://lists.isc.org/mailman/listinfo/dhcp-users
>
--
Thanks & Regards,
Muralikrishna CH
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Message: 2
Date: Mon, 13 May 2019 17:38:36 +0100
From: "Niall O'Reilly" <niall.orei...@ucd.ie>
To: "Users of ISC DHCP" <dhcp-users@lists.isc.org>
Subject: Re: Regarding the dhcp lease time
Message-ID: <a7233f0e-4a1a-40b2-9669-73e6ae2f4...@ucd.ie>
Content-Type: text/plain; format=flowed; markup=markdown
On 13 May 2019, at 16:16, Murali Krishna wrote:
> How the server is calculating the lease time which is not the one
> defined as per the conf file.
What have you configured on the server for the 'default-lease-time'
parameter?
Niall O'Reilly
------------------------------
Message: 3
Date: Mon, 13 May 2019 13:54:40 -0300
From: Bruce Hudson <bruce.hud...@dal.ca>
To: Users of ISC DHCP <dhcp-users@lists.isc.org>
Subject: Re: Regarding the dhcp lease time
Message-ID: <20190513165440.ga31...@kil-bah-1.its.dal.ca>
Content-Type: text/plain; charset=us-ascii
On Mon, May 13, 2019 at 08:46:46PM +0530, Murali Krishna wrote:
> In the current scenario client requested for the respective lease for the
> time duration as mentioned in the conf file.
>
> Here is the sequence of flow it happened:
> 1. Client initiates DHCP Request for 3600s(1hr)
> 2. Server acknowledges(DHCP Ack) with lease time:(158253440s) 1831 days, 15
> hours, 17 minutes, 20 seconds
>
> How the server is calculating the lease time which is not the one defined
> as per the conf file.
I suspect your timeline is incomplete. Let me propose an alternative (for
which, I confess, I have no real evidence):
1. Client initiates DHCP Request for 3600s(1hr)
2. Server acknowledges this lease and records it in the lease file,
ending at an absolute time of "now+1 hour".
3. System admin sets the clock back 5 years.
4. Client initiates DHCP Request for 3600s(1hr)
5. Server acknowledges the existing, still valid lease, ending at an
absolute time the server sees as 5 years in the future.
When you change the clock, are you deleting the existing lease database?
--
Bruce A. Hudson | bruce.hud...@dal.ca
ITS, Networks and Systems |
Dalhousie University |
Halifax, Nova Scotia, Canada | (902) 494-3405
------------------------------
Message: 4
Date: Mon, 13 May 2019 23:50:43 +0530
From: Murali Krishna <muralikris...@gmail.com>
To: Users of ISC DHCP <dhcp-users@lists.isc.org>
Subject: Re: Regarding the dhcp lease time
Message-ID:
<cakhvxa3gfryozqjsvw5eoyps0nxuixyk-fjfrm36qhfzeod...@mail.gmail.com>
Content-Type: text/plain; charset="utf-8"
Hi,
>> What have you configured on the server for the 'default-lease-time'
parameter?
600s is configured in the conf file.
>>When you change the clock, are you deleting the existing lease database?
Nothing is modified w.r.t the lease database.
Thanks & Regards,
Muralikrishna
On Mon, May 13, 2019 at 10:24 PM Bruce Hudson <bruce.hud...@dal.ca> wrote:
> On Mon, May 13, 2019 at 08:46:46PM +0530, Murali Krishna wrote:
>
> > In the current scenario client requested for the respective lease for the
> > time duration as mentioned in the conf file.
> >
> > Here is the sequence of flow it happened:
> > 1. Client initiates DHCP Request for 3600s(1hr)
> > 2. Server acknowledges(DHCP Ack) with lease time:(158253440s) 1831 days,
> 15
> > hours, 17 minutes, 20 seconds
> >
> > How the server is calculating the lease time which is not the one defined
> > as per the conf file.
>
> I suspect your timeline is incomplete. Let me propose an alternative
> (for
> which, I confess, I have no real evidence):
>
> 1. Client initiates DHCP Request for 3600s(1hr)
> 2. Server acknowledges this lease and records it in the lease file,
> ending at an absolute time of "now+1 hour".
>
> 3. System admin sets the clock back 5 years.
>
> 4. Client initiates DHCP Request for 3600s(1hr)
> 5. Server acknowledges the existing, still valid lease, ending at an
> absolute time the server sees as 5 years in the future.
>
> When you change the clock, are you deleting the existing lease
> database?
> --
> Bruce A. Hudson | bruce.hud...@dal.ca
> ITS, Networks and Systems |
> Dalhousie University |
> Halifax, Nova Scotia, Canada | (902) 494-3405
> _______________________________________________
> dhcp-users mailing list
> dhcp-users@lists.isc.org
> https://lists.isc.org/mailman/listinfo/dhcp-users
>
--
Thanks & Regards,
Muralikrishna CH
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Message: 5
Date: Mon, 13 May 2019 20:26:35 +0100
From: Simon Hobson <dh...@thehobsons.co.uk>
To: Users of ISC DHCP <dhcp-users@lists.isc.org>
Subject: Re: Regarding the dhcp lease time
Message-ID: <9c0c4d63-a9c0-4ee3-8031-9cd3f0fe2...@thehobsons.co.uk>
Content-Type: text/plain; charset=us-ascii
Murali Krishna <muralikris...@gmail.com> wrote:
> I agree to your comments that rather than the usecase this is a testcase.
OK, basically you are breaking the system and the system responds in a
correspondingly broken fashion.
Neither the DHCP protocol nor the server & client are designed to handle "time
goes backwards by 5 years" - what happens if you do that is undefined.
If you go to a doctor and say something like "when I do X, it hurts", the
doctor is likely to suggest that you don't do X.
In the same manner, my advice would be to stop breaking things by altering the
clock. Or if you really must alter the clock, stop the DHCP server beforehand
and keep it stopped until you've reset the clock back to the correct time.
And don't expect correct DHCP operations with the server using a self-assigned
link-local address.
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