Script to run on DHCPNAK

Thu Jul 20 18:28:29 UTC 2017

No, the 192 is a cable modem so not much control there. Any control I apply
to it is lost until it boots...per cable labs spec.

On Thu, Jul 20, 2017 at 2:27 PM perl-list <perl-list at network1.net> wrote:

> Mark,
>
> Is it the ISC server that is also handing out the 192.168.100.20 address
> or a different DHCP server?  If its all the same server, I'm thinking class
> {} statements and allow members of "class"; would be the appropriate fix
> right inside the DHCP config...
>
> If it is a different DHCP server that is ALSO ISC that you could modify,
> you could use class {} statements in there to cause it to ignore booting
> from clients it shouldn't serve.
>
> ------------------------------
>
> *From: *"Mark Spring" <mspring at nktelco.com>
> *To: *"Users of ISC DHCP" <dhcp-users at lists.isc.org>
>
> *Sent: *Thursday, July 20, 2017 8:53:11 AM
>
>
> *Subject: *Re: Script to run on DHCPNAK
>
> The trouble is that the end device boots too quick and grabs the 192
> address from the modem(cable labs spec) then moments later it halts and
> asks for all the information that would normally be in the DHCP options.
> The lease from the modem expires, it requests...server NAK's it. It then
> gets all the proper info but the client doesn't read in all of the options.
> In a perfect world I have advised the vendor to read in the options and
> continue with the client. In the real world, I am trying to setup things so
> when I see a NAK, I execute a script...if it matches an OUI then I lookup
> the IP that it received, SSH into the client and reboot it. The modem is
> online and everything starts up normal. We are essentially building a
> reboot script into the client where it reboots if it fails to receive
> options the first time around.
> Hope this helps, thanks for replying!
>
>
> Mark Spring
> Information Systems Manager
>
> On Thu, Jul 20, 2017 at 8:45 AM, perl-list <perl-list at network1.net> wrote:
>
>> Mark,
>>
>> That is completely normal.  The device 00:03:e6:6f:42:14 previously had
>> an address of 192.168.100.20 and attempted to renew such address.
>> Apparently that address is not valid on the network your DHCP server is
>> on.  So, a NAK was sent followed by a discover from the client.  The client
>> and server then negotiated a 10.4.2.191 address.
>>
>> What is the actual problem that you are having as I am not sure this has
>> anything to do with it...
>>
>> ------------------------------
>>
>> *From: *"Mark Spring" <mspring at nktelco.com>
>> *To: *"Users of ISC DHCP" <dhcp-users at lists.isc.org>
>> *Sent: *Thursday, July 20, 2017 8:31:30 AM
>> *Subject: *Re: Script to run on DHCPNAK
>>
>> isc, just one server  here is an example
>> *Jul 19 10:04:36 dhcp dhcpd: DHCPREQUEST for 192.168.100.20 from
>> 00:03:e6:6f:42:14 via 10.4.0.1 <http://10.4.0.1>: wrong net*
>> *Jul 19 10:04:36 dhcp dhcpd: DHCPNAK on 192.168.100.20 to
>> 00:03:e6:6f:42:14 via 10.4.0.1*
>> *Jul 19 10:04:39 dhcp dhcpd: DHCPDISCOVER from 00:03:e6:6f:42:14 via
>> 10.4.0.1*
>> *Jul 19 10:04:40 dhcp dhcpd: DHCPOFFER on 10.4.2.191 to 00:03:e6:6f:42:14
>> via 10.4.0.1*
>> *Jul 19 10:04:40 dhcp dhcpd: DHCPREQUEST for 10.4.2.191 (192.168.100.3)
>> from 00:03:e6:6f:42:14 via 10.4.0.*
>> *Jul 19 10:04:40 dhcp dhcpd: DHCPACK on 10.4.2.191 to 00:03:e6:6f:42:14
>> via 10.4.0.1*
>>
>>
>>
>> Mark Spring
>> Information Systems Manager
>>
>> On Thu, Jul 20, 2017 at 8:22 AM, perl-list <perl-list at network1.net>
>> wrote:
>>
>>>
>>> Are the NAK and ACK coming from the same server?  Can you post example
>>> log messages of the NAK and ACK and related communication?  I assume this
>>> is ISC DHCP that we are speaking of and not some proprietary DHCP server?
>>>
>>> ------------------------------
>>>
>>>
>>> I am having some issues with network gear, and while arguing with
>>> vendors about who's problem it really is..I noticed that my device receives
>>> a NAK before it receives the proper IP address from our server(when the
>>> gear comes back online). If I can track this down in the logs then I can
>>> look for the ACK that follows, login to the device and reboot it properly.
>>>
>>> ___
>>>
>>>
>>>
>>> _______________________________________________
>>> dhcp-users mailing list
>>> dhcp-users at lists.isc.org
>>> https://lists.isc.org/mailman/listinfo/dhcp-users
>>>
>>
>>
>> NKTelco
>> 301 W. South St.
>> New Knoxville, OH 45871
>>
>> Phone: 1-888-NKTELCO
>> Fax: 419-753-2950 <(419)%20753-2950>
>>
>> This message and the file(s) attached are confidential and proprietary
>> information of NKTelco for the sole use of the intended recipient. Any
>> unauthorized review, distribution, disclosure, copying, use, or
>> dissemination, either whole or in part, is strictly prohibited. Do not
>> transmit these documents, in any form, to any third party without the
>> expressed written permission of NKTelco.
>>
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>> https://lists.isc.org/mailman/listinfo/dhcp-users
>>
>>
>>
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>
>
> NKTelco
> 301 W. South St.
> New Knoxville, OH 45871
>
> Phone: 1-888-NKTELCO
> Fax: 419-753-2950
>
> This message and the file(s) attached are confidential and proprietary
> information of NKTelco for the sole use of the intended recipient. Any
> unauthorized review, distribution, disclosure, copying, use, or
> dissemination, either whole or in part, is strictly prohibited. Do not
> transmit these documents, in any form, to any third party without the
> expressed written permission of NKTelco.
>
> _______________________________________________
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> dhcp-users at lists.isc.org
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>
> _______________________________________________
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-- 

Mark Spring
Information Systems Manager

-- 
NKTelco
301 W. South St.
New Knoxville, OH 45871

Phone: 1-888-NKTELCO
Fax: 419-753-2950

This message and the file(s) attached are confidential and proprietary
information of NKTelco for the sole use of the intended recipient. Any 
unauthorized review, distribution, disclosure, copying, use, or 
dissemination, either whole or in part, is strictly prohibited. Do not 
transmit these documents, in any form, to any third party without the 
expressed written permission of NKTelco.
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