Option negation

[Patrick Trapp]

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 [dhcp-users-bounces at lists.isc.org] on behalf of Glenn Satchell [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
> https://lists.isc.org/mailman/listinfo/dhcp-users


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