Issues with dhcpv6 and ddns updates

[Thomas Markwalder]

On 12/2/16 11:11 AM, perl-list wrote:
>
>
> ------------------------------------------------------------------------
>
>     *From: *"Thomas Markwalder" <tmark at isc.org>
>     *To: *dhcp-users at lists.isc.org
>     *Sent: *Friday, December 2, 2016 11:02:32 AM
>     *Subject: *Re: Issues with dhcpv6 and ddns updates
>
>     On 12/2/16 10:07 AM, perl-list wrote:
>
>         Robert,
>
>         I don't know anything about DDNS updates as I have never used
>         them, but I can confirm that on release {} in DHCPv6 does not
>         seem to have access to any of the option data.  I had the same
>         problem and asked the list about it more than a week ago.  I
>         was met with silence.  If a developer could comment on this
>         being a bug or simply not implemented yet, that would be
>         great.  Target for inclusion of option data in on release {}
>         statements?
>
>         ------------------------------------------------------------------------
>
>             Hello Robert:
>
>     Sorry for the belated reply, ISC is a small non-profit with
>     limited resources and we do what we can.  Contributions are always
>     welcome.   In order to make options available during releases,
>     regardless of whether we're discussing v4 of v6, the server would
>     have to execute all of the configuration statements down to
>     appropriate scope as is done when granting or renewing leases.  
>     The same applies to lease expiration processing.
>
>     As to why this has never been added I cannot say, however adding
>     it might have unintended consequences.  It is something we we
>     would have to examine closely and if we were to add, it would be
>     disabled by default, enabled with a run time option.  If you
>     submit a feature request by emailing  dhcp-suggest at isc.org, I will
>     add it to the list of items under consideration for inclusion in
>     4.4.0 release, due sometime in 2017 (date is TBD).
>
>
>     Sincerely,
>
>     Thomas Markwalder
>
>     ISC Software Engineering
>
>
>
> I don't think that could be right that options are not available in on
> release {} in DHCPv4 as a statement like this:
>
> on release {
>
>         log( error, 
>
> concat( "RELEASED,",
>
>                         "ip,", binary-to-ascii (10, 8, ".",
> leased-address),",",
>
>                        
> "hardware,",binary-to-ascii(16,8,":",substring(hardware,1,7))
>
>                 )
>
>         );
>
> }
>
>
>
> produces a line like this:
>
> RELEASED,ip,192.168.0.1,hardware,01:02:03:02:01:00
>
> in the logs.
>
>
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>
>
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Let me clarify.  Some options are going to available, such as
leased-address, but not all options will be.  Any option value which has
been configured in the server configuration to be the result of
expression which must be evaluated, potentially at scopes down to the
pool level is not going to have a value, as the statements are simply
not executed during release processing.

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