Re: [dane] An AD bit discussion

Tony Finch <dot@dotat.at> Wed, 26 February 2014 18:14 UTC

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Date: Wed, 26 Feb 2014 18:14:09 +0000
From: Tony Finch <dot@dotat.at>
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Subject: Re: [dane] An AD bit discussion
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Viktor Dukhovni <viktor1dane@dukhovni.org>; wrote:
>
> It is in fact problematic if both 127.0.0.1 and another nameserver
> are listed.  The correct semantics of that are hard to define.  It
> makes more sense to define a boolean primitive that marks all the
> nameservers collectively as either trusted or not.

Yes.

> The RES_USE_DNSSEC flag turns on the "DO" bit.  I would be surprised
> if RES_USE_EDNS0 enabled "DO".

Er yes, you are right. I was confused by the way ssh uses the resolver: it
sets RES_USE_DNSSEC only if RES_USE_EDNS0 is set, so putting "options
edns0" in /etc/resolv.conf turns on ssh's trust-AD behaviour. There
is not a separate resolv.conf option for DNSSEC. Grotty.

(Note that when I make statements about resolver behaviour I am checking
boh FreeBSD and glibc - they are pretty consistent in all this.)

> As for setting the "AD" bit in the request automatically, it probably
> should still require an explicit indication of interest from the
> application or be set via a default option value /etc/resolv.conf.

Perhaps, though I think the AD flag is pretty benign.

Tony.
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