nanog mailing list archives

Re: Should host/domain names travel over the internet with a trailing dot?


From: Jay Ashworth <jra () baylink com>
Date: Mon, 25 Feb 2013 11:26:47 -0500 (EST)

----- Original Message -----
From: "Brian Reichert" <reichert () numachi com>

My understanding is this:

Unless you're doing client certificate verification (wherein the
server is making decisions about which clients attempting a
connection), all validation/verification is done by the client.

Right; my apologies; I know better than to post Before Coffee.  :-)

The SSL client retrieves the server's certificate, and the set of
values in the Subject and the Subject Alternative Name is compared
against the hostname/IP address used to initiate the process. This
comparison is (to my understanding) straight-forward (modulo UTF8
encodings, etc.).

The upshot (assuming I'm not totally off base here), is that other
than getaddrinfo(), nothing is acting on the semantics of the
supplied hostname (or IP address). They are 'just strings', and
are (essentially) compared as such.

Right.  And I'm asserting that that's wrong: the client side libraries
Really Ought To normalize that name before trying to compare it against
the retrieved certificate to see if it matches, which would relieve you
of having to have the altName with the trailing dot in such a cert.

The controlling standard *appears* to be RFC 2246, TLS v1.0.  I'm doing
some work this morning, but that's up in a tab for coffee breaks; I'll 
try to figure out what I think Dierks and Allen thought about this topic,
if anything, during the day.

Cheers,
-- jra
-- 
Jay R. Ashworth                  Baylink                       jra () baylink com
Designer                     The Things I Think                       RFC 2100
Ashworth & Associates     http://baylink.pitas.com         2000 Land Rover DII
St Petersburg FL USA               #natog                      +1 727 647 1274


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