Option negation

John Hascall john at iastate.edu
Wed May 4 12:20:02 UTC 2016


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> 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 [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
>
>
> _______________________________________________
> dhcp-users mailing list
> dhcp-users at lists.isc.org
> https://lists.isc.org/mailman/listinfo/dhcp-users
> _______________________________________________
> dhcp-users mailing list
> dhcp-users at lists.isc.org
> https://lists.isc.org/mailman/listinfo/dhcp-users
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://lists.isc.org/pipermail/dhcp-users/attachments/20160504/7d072f5c/attachment-0001.html>


More information about the dhcp-users mailing list