Option negation

[Patrick Trapp]

The only reason I am replying at this hour is because I should be working on something else, but there's an idea I can't quite fully express that a single device should be doable here.

Hopefully I have time when the thought fully forms to share it. Heck, maybe I can test it even!

PS to your PS: I'm not sure where a person enters feature requests, but I believe what attention you will get from ISC-affiliated individuals on this list is on their own time, so an official response might require a more official route. Enough people making the request should see it move up in importance. Just my opinion, though.

On May 4, 2016, at 7:20 AM, John Hascall <john at iastate.edu<mailto:john at iastate.edu>> wrote:

Unfortunately, I can't think of any way to do that.

We have many thousands of IP phones.  I don't even have a list of them,
all I have is the MAC prefix that I use to assign them to a group.
The group sets their options, now I have a request that this one specific
phone not get the options.

Thanks though!

John

On Wed, May 4, 2016 at 7:10 AM, Patrick Trapp <ptrapp at nex-tech.com<mailto:ptrapp at nex-tech.com>> wrote:
I had not realized that a host entry would inherit from more general configuration entries. It's not something I've really looked at despite many active host entries on my system.

Can you reverse the order so that the configuration without an option is what the larger group qualifies for first and your devices requiring the specific option are the ones that are the special cases.

Alternatively, can you disqualify the devices requiring no option so they do not receive the configuration with the unwanted option at all? Same idea, potentially very different execution.

Patrick

________________________________________
From: dhcp-users-bounces at lists.isc.org<mailto:dhcp-users-bounces at lists.isc.org> [dhcp-users-bounces at lists.isc.org<mailto:dhcp-users-bounces at lists.isc.org>] on behalf of Glenn Satchell [glenn.satchell at uniq.com.au<mailto:glenn.satchell at uniq.com.au>]
Sent: Wednesday, May 04, 2016 1:20 AM
To: Users of ISC DHCP
Subject: Re: Option negation

This topic comes up from time to time. Unfortunately there is no way to
remove an option. The best you can currently do is set it to a null or
empty string, but this is not the same as not sending the option.

regards,
-glenn

On Wed, May 4, 2016 6:11 am, John Hascall wrote:
> I know that options set in more specific scopes override those set in less
> specific scopes, but can I "undo" an option setting?  That is, lets
> imagine
> I have this:
>
> option option-66 code 66 = text;
>
>
> and then in a class scope, I have:
>
> class "someclass" {
> ​​
> ​        ​
> match substring(hardware, 1, 3);
> ​        ​
>
> *option option-66 "blah blah blah";*}
> subclass "
> ​someclass
> " 00:0
> ​1​
> :
> ​02​
> ;
>
>
> I know that, given that host whatever falls in that class scope, that:
>
> host whatever {
>
> ​        hardware ethernet 00:01:02:03:04:05;​
>
> ​
> *option option-66 "fe fi fo fum";*
> }
>
>
> works
> ​ to change its option​
> , but what if
> ​I ​
> want *host whatever* not to get
> ​ that option at all?  How do I do that???
>
> host whatever {
> ​        ​
> hardware ethernet 00:01:02:03:04:05;​
>
>         *no option​ option-66;       <== just making this up*
> }
>
>
> ​Many Thanks!
> John​
> _______________________________________________
> dhcp-users mailing list
> dhcp-users at lists.isc.org<mailto:dhcp-users at lists.isc.org>
> https://lists.isc.org/mailman/listinfo/dhcp-users


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