VS: Change DNSSEC algorithm and switch to use KASP

[Jukka Pakkanen]

I just did the same operation in our BIND servers, converted all DNSSEC enabled zones with different algorithms to KASP/dnssec-policy and ecdsa256/13.

All I did was replaced the two lines in named.conf:

    inline-signing yes;
    auto-dnssec maintain;

to 

   dnssec-policy "ecdsa256";

And of course created the policy there too.

If the algorithm in the zone was changed (previously something else than "13"), updated the DS record at the registrar as well.

Worked out smoothly, ok there was a brief moment before the new DS was published and zone secured again, but did this at night time, at the morning everything was perfect, and now all zones using that policy.

Jukka


-----Alkuperäinen viesti-----
Lähettäjä: bind-users <bind-users-bounces at lists.isc.org> Puolesta Matthias Fechner
Lähetetty: 25. huhtikuuta 2020 10:08
Vastaanottaja: bind-users at lists.isc.org
Aihe: Change DNSSEC algorithm and switch to use KASP

Dear all,

I followed now the series here (again, thanks a lot to make this public!):
https://www.youtube.com/watch?v=MheHMWCOTvE&list=PLUwyH0o3uuICgnbQj_lQajRI_CzewZr7q

Just now I only sign one domain which is using the "auto-dnssec maintain;".
What I understood from the series is that KASP does not support switching from "auto-dnssec maintain" to KASP, yet.

As my single domain is using RSASHA256 and I want to use one algorithm
(ECDSA256)  for each domain I maintain in my DNS servers (to would like to have a clean start with KASP).
I just wanted to make sure I do not break this single domain
(fechner.net) which is already signed.
I cannot remove DNSSEC before the DS has disappeared on the parent.

What I understood so far is using the following procedure (to disable DNSSEC for this single specific domain):
- ask the parent zone to remove the DS (as long as the DS exists in the parent zone I must not remove DNSSEC as that would break the zone)
- after the DS disappeared in the parent zone, wait for at least the TTL of the DS (86400) + maybe one day (safety)
- now my zone does not require to have DNSSEC and I can remove DNSSEC
- instruct bind to delete the key using dnssec-settime to remove the key (dnssec-settime -I +1d -D +2d keyfile)
- wait 2 days
- check no RRSIGS are existing for the domain
- wait for one day (TTL) + 1 say (safety) = at least 2 days
- now start to use KASP and let it create keys and sign your zone using
ecdsa256 (is this a recommended algo for using DNSSEC?)
- wait till CDS and CDNSKEY appears in the zone (bind ensures here the TTLs match, so it will not add the CDS before required time is passed)
- ask parent to add the DS to their zone
- the moment the DS is added on parent, DNSSEC is enforced

If I do not ask the parent to add the DS key, I can keep DNSSEC for the zones, but it will not be enforced or?
(this does not work if the registra would import the DS because CDS and CDNSKEY keys are existing, so be carefull here)

I'm talking here about zone fechner.net.

The TTL on the parent seems to be 86400:
dig +dnssec +multi -t DS fechner.net. @A.GTLD-SERVERS.NET ...
fechner.net.            86400 IN DS 64539 10 2 (
                                12860767104BEE7B250F03B5D03425BC978F65CB426E
                                EDC9C9B541AFB5D52D8D ) fechner.net.            86400 IN DS 64539 10 1 (
                                81EF72A9B9D92A9FD4F50856D1371DA05F5ACC27 ) ...

The TTL in my zone is also 86400, so I used this for all waiting times.

Thanks a lot for any comments!

Gruß
Matthias

-- 

"Programming today is a race between software engineers striving to build bigger and better idiot-proof programs, and the universe trying to produce bigger and better idiots. So far, the universe is winning." -- Rich Cook


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