Dhcpd randomly returns the IP address or the backup IP

Wed Mar 31 12:07:50 UTC 2021

I made a mistake and that file has all the mysql and dhcp in it. Oops. Oh
well.

I have no doubt it wil lhappen again because this happens on all the hosts
I test on.

<https://connect-mobile.co.za/mobile_marketing_solutions/>

On Wed, 31 Mar 2021 at 13:51, Sten Carlsen <stenc at s-carlsen.dk> wrote:

>
>
> On 31 Mar 2021, at 13.42, Wayne Gemmell | Connect <
> wayne at connect-mobile.co.za> wrote:
>
> Hi
>
> I've posted a pcap file of the process. There is nothing hitting at
> exactly the same moment but I'm digging into how to trigger this
> differently.
>
>
> https://drive.google.com/file/d/1mYIIlhq7JPdszT1zeasREIYcP4Fnj1lj/view?usp=sharing
>
>
> I will take a look, but as Glenn mentioned this will likely be down to the
> process the code uses to select a suitable and available address.
>
> One thing you may want to try:
>
> Stop the servers, edit the leases file to remove any mention of the
> undesired address and restart the servers. They will initialise using the
> information in the leases file and then the host has only one address that
> it has ever used.
>
> This should work until for some reason it gets a different address once -
> then this will start again.
>
>
>
>
> <https://connect-mobile.co.za/mobile_marketing_solutions/>
>
>
> On Mon, 29 Mar 2021 at 18:27, Sten Carlsen <stenc at s-carlsen.dk> wrote:
>
>> Hi
>>
>> These two addresses are both in the same pool, so nothing illegal is
>> happening. It is still odd that it sometimes gets one address and then the
>> other, this should not happen.
>>
>> Consider the leases file as a historical document, each time something
>> happens, the leases file gets added to. Once in a while it gets regenerated
>> with just the current status of all leases.
>>
>> So for this sequence of events you should be able to reconstruct what
>> happened by looking into this file.
>>
>> One thing that comes to mind is timing. The release and the discover
>> happens in the same second, so what if the server could not write to the
>> leases file before being asked about a new lease - this is not extending an
>> existing lease as the discover indicates that the device does not have an
>> address at this moment.
>>
>> Would it be possible to add a pause of a few seconds between the release
>> and the discover? at least for an experiment. If that works, some timing is
>> at the bottom of this.
>>
>> Possibly a wireshark trace could reveal the exact timing of these two
>> messages.
>>
>> The leases file snippet did also not have both addresses as active, which
>> could uncover other interesting things.
>>
>> --
>> Best regards
>> Sten Carlsen
>>
>> A pessimist is a person that can find a problem for every solution.
>>
>>
>> On 29 Mar 2021, at 12.05, Wayne Gemmell | Connect <
>> wayne at connect-mobile.co.za> wrote:
>>
>> Hi Sten
>>
>> One of the host I've been testing with in the kannel pool alternates
>> between the following
>>
>>     inet 10.3.2.36/16
>>     inet 10.3.2.60/16
>>
>> Leases look as follows. I don't really understand why each would be both
>> free and active.
>>
>> Here's the log file of the responsible peer:
>> https://pastebin.com/UP6M1Lic
>>
>> DHCP Lease list on responsible peer. The other one has similar data but
>> no host names. https://pastebin.com/WX3NwkM2
>>
>> Here's snippet of the lease file https://pastebin.com/fKFiZpQ0
>>
>> <https://connect-mobile.co.za/mobile_marketing_solutions/>
>>
>>
>> On Fri, 26 Mar 2021 at 19:32, Sten Carlsen <stenc at s-carlsen.dk> wrote:
>>
>>>
>>> Thanks
>>>
>>> Sten
>>>
>>> On 26 Mar 2021, at 08.43, Wayne Gemmell | Connect <
>>> wayne at connect-mobile.co.za> wrote:
>>>
>>> Thanks Sten
>>>
>>> I've moved my class out of the subnet  and the issue still persists.
>>>
>>>
>>> Well, that is one can of worms out of the picture.
>>>
>>> What are the two addresses?
>>>
>>>
>>>
>>>
>>> <https://connect-mobile.co.za/mobile_marketing_solutions/>
>>>
>>>
>>> On Thu, 25 Mar 2021 at 17:51, Sten Carlsen <stenc at s-carlsen.dk> wrote:
>>>
>>>> You define the class kannel inside the subnet, so if there are any
>>>> other subnets, it will be defined there as well. Class definitions are
>>>> global always, defining them inside a subnet may have some "interesting"
>>>> side effects as some options are taken from that subnet even if the host
>>>> gets an address in a different subnet - routers is one of them.
>>>>
>>>> So one thought is, if the backup address is not in this subnet, the
>>>> host will be given incorrect information.
>>>>
>>>> --
>>>> Best regards
>>>> Sten Carlsen
>>>>
>>>> --------------------------------------------------
>>>> Aoccdrnig to rseerach at Cmabrigde Uinervtisy,
>>>> it deosn't mttaer in waht oredr the ltteers in a
>>>> wrod are, the olny iprmoatnt tihng is taht the
>>>> frist and lsat lteter be at the rghit pclae.
>>>> The rset can be a ttoal mses and you can slitl
>>>> raed it wotihut porbelm. Tihs is bcuseae the
>>>> hmuan mnid deos not raed ervey lteter by istlef,
>>>> but the wrod as a wlohe. Amzanig, huh?
>>>> --------------------------------------------------
>>>>
>>>> On 25 Mar 2021, at 13.01, Wayne Gemmell | Connect <
>>>> wayne at connect-mobile.co.za> wrote:
>>>>
>>>> I tried it. No change. The issue still persists.
>>>>
>>>>
>>>> <https://connect-mobile.co.za/mobile_marketing_solutions/>
>>>>
>>>>
>>>> On Tue, 23 Mar 2021 at 16:19, Wayne Gemmell | Connect <
>>>> wayne at connect-mobile.co.za> wrote:
>>>>
>>>>> I'll give it a try, thanks.
>>>>>
>>>>>
>>>>> <https://connect-mobile.co.za/mobile_marketing_solutions/>
>>>>>
>>>>>
>>>>> On Tue, 23 Mar 2021 at 01:32, Bill Shirley <
>>>>> bill at c3po.polymerindustries.biz> wrote:
>>>>>
>>>>>> Try:
>>>>>> update-optimization             off;
>>>>>>
>>>>>> Bill
>>>>>> On 3/19/2021 2:22 AM, Wayne Gemmell | Connect wrote:
>>>>>>
>>>>>> Hi
>>>>>>
>>>>>> When my dhcp server gets a DHCPRELEASE followed by a DHCPDISCOVER
>>>>>> then it randomly allocates the IP address or the backup IP address that are
>>>>>> assigned to the host in the lease file to the host. The assignments always
>>>>>> got to the correct host and the mac address doesn't change.
>>>>>>
>>>>>> When this backup IP address is allocated then dynamic DNS isn't
>>>>>> updated and my container is unreachable.
>>>>>>
>>>>>> I've put all the relevant details in the link below but am more than
>>>>>> happy enough to furnish anything that is missing. Can anyone help please?
>>>>>>
>>>>>> https://gitlab.isc.org/isc-projects/dhcp/-/issues/172
>>>>>>
>>>>>> <https://connect-mobile.co.za/mobile_marketing_solutions/>
>>>>>>
>>>>>> _______________________________________________
>>>>>> ISC funds the development of this software with paid support subscriptions. Contact us at https://www.isc.org/contact/ for more information.
>>>>>>
>>>>>> dhcp-users mailing listdhcp-users at lists.isc.orghttps://lists.isc.org/mailman/listinfo/dhcp-users
>>>>>>
>>>>>> _______________________________________________
>>>>>> ISC funds the development of this software with paid support
>>>>>> subscriptions. Contact us at https://www.isc.org/contact/ for more
>>>>>> information.
>>>>>>
>>>>>> dhcp-users mailing list
>>>>>> dhcp-users at lists.isc.org
>>>>>> https://lists.isc.org/mailman/listinfo/dhcp-users
>>>>>>
>>>>> _______________________________________________
>>>> ISC funds the development of this software with paid support
>>>> subscriptions. Contact us at https://www.isc.org/contact/ for more
>>>> information.
>>>>
>>>> dhcp-users mailing list
>>>> dhcp-users at lists.isc.org
>>>> https://lists.isc.org/mailman/listinfo/dhcp-users
>>>>
>>>>
>>>> _______________________________________________
>>>> ISC funds the development of this software with paid support
>>>> subscriptions. Contact us at https://www.isc.org/contact/ for more
>>>> information.
>>>>
>>>> dhcp-users mailing list
>>>> dhcp-users at lists.isc.org
>>>> https://lists.isc.org/mailman/listinfo/dhcp-users
>>>>
>>> _______________________________________________
>>> ISC funds the development of this software with paid support
>>> subscriptions. Contact us at https://www.isc.org/contact/ for more
>>> information.
>>>
>>> dhcp-users mailing list
>>> dhcp-users at lists.isc.org
>>> https://lists.isc.org/mailman/listinfo/dhcp-users
>>>
>>>
>>> _______________________________________________
>>> ISC funds the development of this software with paid support
>>> subscriptions. Contact us at https://www.isc.org/contact/ for more
>>> information.
>>>
>>> dhcp-users mailing list
>>> dhcp-users at lists.isc.org
>>> https://lists.isc.org/mailman/listinfo/dhcp-users
>>>
>> _______________________________________________
>> ISC funds the development of this software with paid support
>> subscriptions. Contact us at https://www.isc.org/contact/ for more
>> information.
>>
>> dhcp-users mailing list
>> dhcp-users at lists.isc.org
>> https://lists.isc.org/mailman/listinfo/dhcp-users
>>
>>
>> _______________________________________________
>> ISC funds the development of this software with paid support
>> subscriptions. Contact us at https://www.isc.org/contact/ for more
>> information.
>>
>> dhcp-users mailing list
>> dhcp-users at lists.isc.org
>> https://lists.isc.org/mailman/listinfo/dhcp-users
>>
> _______________________________________________
> ISC funds the development of this software with paid support
> subscriptions. Contact us at https://www.isc.org/contact/ for more
> information.
>
> dhcp-users mailing list
> dhcp-users at lists.isc.org
> https://lists.isc.org/mailman/listinfo/dhcp-users
>
>
> _______________________________________________
> ISC funds the development of this software with paid support
> subscriptions. Contact us at https://www.isc.org/contact/ for more
> information.
>
> dhcp-users mailing list
> dhcp-users at lists.isc.org
> https://lists.isc.org/mailman/listinfo/dhcp-users
>
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