GSS-TSIG update policy identity field

[Jan-Piet Mens]

> So I look for a way that I can say that all clients from EXAMPLE.TEST are
> allowed to update their own record (or whatever).

Sounds like a task for update-policy external [1], but note that that
requires updates to be sent via TCP and not UDP. [2]

        -JP

[1]: https://lists.isc.org/pipermail/bind-workers/2011-March/002975.html
[2]: https://lists.isc.org/pipermail/bind-workers/2011-March/002976.html