DNSSEC - many doubts
warren at kumari.net
Thu Apr 2 15:58:38 UTC 2020
On Thu, Apr 2, 2020 at 11:14 AM David Alexandre M. de Carvalho
<david at di.ubi.pt> wrote:
> Hello, good afternoon.
> My first post in this list :)
> I'm running BIND Chroot for many years (currently version 9.8.2) on some old hardware running Oracle Linux 6.
> I believe it was last year when I was reading about implementing DNSSEC, and I think I've even tried to generate a
> keypair in the slowest server, which after more than a day, wasn't ready yet. Maybe I was doing something wrong, I
> honestly don't know.
You almost definitely were -- even a really really slow machine should
be able to generate keys in a small number of seconds -- you didn't
list what commands you used, but I'm going to assume you were trying
to generate an rsa key - you should be able to get a feel for how long
this takes by running:
time openssl genrsa -out private.key 2048
time openssl genrsa -out private.key 4096
(note that this is very different to running 'openssl speed rsa2048
rsa4096', which benchmarks RSA operations, not key generations).
I'm fairly sure that your issue was a lack of entropy -- in order to
generate crypograohically good keys, you need good a good source of
randomness. If you are running an older machine and older kernel, the
/dev/random source is blocking, and if you try and read too much from
it it will just hang until it has enough entropy to give "safe"
output. Newer kernels do a better job of mixing in external event
noise, but there are a number of modules which help with this -
haveged being the best known (http://www.issihosts.com/haveged/ ).
You could also test if this is the issue by using /dev/urandom, which
doesn't block, or 'while true; do cat
/proc/sys/kernel/random/entropy_avail; sleep 2; done' and see if the
available entropy drops to zero during key generation...
> So now I had some time and reading about this again.
> If I query either of my servers about my domain:
> dig @dns di.ubi.pt DNSKEY
> I do get the DNSKEY, but I have no records when querying about +dnssec. My topdomain (ubi.pt) doesn't have DNSSEC yet
> my named.conf already has the following:
> dnssec-enable yes;
> dnssec-validation auto;
> dnssec-lookaside auto;
> bindkeys-file "/etc/named.iscdlv.key";
> managed-keys-directory "/var/named/dynamic";
> Outside the configuration file I also have a /etc/named.root.key
> My questions:
> 1) Will my old servers (1GB RAM) become much slower with DNSSEC? Is it worth it?
> 2) I have one global "hosts" file and 3 reverse zone files, each for the respective IP network. Can I use the same
> Keypair in all of them?
> 3) Are the files /etc/named.root.key file and /etc/named.iscdlv.key already being used? I compared them to the result
> of the DNSKEY dig query but they are different.
> Thank you so much for your time!
> Best regards
> Os melhores cumprimentos
> David Alexandre M. de Carvalho
> Especialista de Informática
> Departamento de Informática
> Universidade da Beira Interior
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I don't think the execution is relevant when it was obviously a bad
idea in the first place.
This is like putting rabid weasels in your pants, and later expressing
regret at having chosen those particular rabid weasels and that pair
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