Thanks for the clarification.

In terms of config options, I assume we are talking about the following:
dnssec-loadkeys-interval (with a default of 60 minutes)
sig-validity-interval (with a default of 30 days)

So…

A new key should be published for at least [sig-validity-interval] before 
deletion of the old key to allow for sufficient time for the signatures to roll 
over to the newer key. Presumably anything less may cause a potential extended 
use of the old key (beyond expiration and possibly even deletion times).

As far as removing the underlying key file, it sounds like the best practice 
would be to wait until the key has been removed from DNS (after deletion time, 
but possibly later if other configs are not sane) - plus waiting an additional 
dnssec-loadkeys-interval before finally removing the underlying file.

With both of the above in place, auto-dnssec maintain should do its thing and 
not hang onto zombie keys anymore.

Does all of that sound right?

Thanks again,

-Mathew Eis

From: Tony Finch <d...@dotat.at>
Date: Tuesday, July 5, 2016 at 10:48 AM
To: Mathew Eis <mathew....@nau.edu>, "bind-users@lists.isc.org" 
<bind-users@lists.isc.org>
Subject: Re: auto-dnssec maintain and DNSKEY removal

Mathew Ian Eis <mathew....@nau.edu> wrote:
>
> > Are you allowing enough time for named to go through a zone key maintenance 
> > cycle? (which is hourly if I remember correctly)
>
> I’m not sure, it sounds like perhaps not always? You’ve mentioned a “zone
> key maintenance cycle” of an hour, and the docs also casually mention
> that “by default, this [key] rollover completes in 30 days” [1].

These are two separate things.

The zone key maintenance timer controls when named re-examines a zone's keys 
(checks for changes to the files, loads new keys, etc.) I haven't checked this 
myself in detail, but named can get confused and upset if a key file disappears 
while named thinks the key is still in use, so I suspect it might go wrong if 
the file is deleted after the key deletion time but before the zone key timer 
triggers.

The rollover time is related to the signature lifetime - you have to stop 
signing with a key, allow a month for the signatures to be replaced, then 
delete the key, and you specify all this with dnssec-settimes, and check it is 
sane with dnssec-coverage. (Which I am sure you know but I wanted to avoid 
confusion.)

> How long after deletion time is it safe to actually remove the underlying
> key files, if it isn’t the deletion time itself?

You should probably augment your key file deletion script to verify that the 
key has in fact gone from the zone - if you add suitable warning diagnostics it 
will probably reveal what is actually going wrong, more reliably than my 
guesses!

Tony.
--
f.anthony.n.finch  <d...@dotat.at>  http://dotat.at/  -  I xn--zr8h punycode


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