Re: [TLS] RFC-4366-bis and the unrecognized_name(112) alert

"Joseph Salowey (jsalowey)" <jsalowey@cisco.com> Thu, 03 June 2010 14:03 UTC

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Date: Thu, 3 Jun 2010 07:02:43 -0700
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Thread-Topic: [TLS] RFC-4366-bis and the unrecognized_name(112) alert
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From: "Joseph Salowey (jsalowey)" <jsalowey@cisco.com>
To: "Nikos Mavrogiannopoulos" <nmav@gnutls.org>
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Subject: Re: [TLS] RFC-4366-bis and the unrecognized_name(112) alert
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If we are going to make a change then we need some suggested text. 

Joe

> -----Original Message-----
> From: n.mavrogiannopoulos@gmail.com
> [mailto:n.mavrogiannopoulos@gmail.com] On Behalf Of Nikos
> Mavrogiannopoulos
> Sent: Thursday, June 03, 2010 12:24 AM
> To: Joseph Salowey (jsalowey)
> Cc: Michael D'Errico; mrex@sap.com; tls@ietf.org
> Subject: Re: [TLS] RFC-4366-bis and the unrecognized_name(112) alert
> 
> I believe that it is quite bad practice to delegate to application
> protocol. This is protocol stack signalling and shouldn't be
> application specific. Otherwise interoperability problems occur. A
> protocol spec should be clear on what it does.
> 
> regards,
> Nikos
> 
> On Thu, Jun 3, 2010 at 7:22 AM, Joseph Salowey (jsalowey)
> <jsalowey@cisco.com> wrote:
> > It seems that the behavior is dependent upon the application.  I'm
> not
> > sure we would come up with useful text here.  In the interest of
> getting
> > this document published I suggest we leave it as is.
> >
> > Joe
> >
> >> -----Original Message-----
> >> From: tls-bounces@ietf.org [mailto:tls-bounces@ietf.org] On Behalf
> Of
> >> Michael D'Errico
> >> Sent: Tuesday, May 25, 2010 10:58 AM
> >> To: mrex@sap.com
> >> Cc: tls@ietf.org
> >> Subject: Re: [TLS] RFC-4366-bis and the unrecognized_name(112) alert
> >>
> >> Martin Rex wrote:
> >> > Michael D'Errico wrote:
> >> >> In my server code, the SNI is checked to see if there is a
> matching
> >> >> virtual host with that domain name.  If there is, then no alert
> is
> >> >> sent.  If there is no matching virtual host, then it checks
> whether
> >> >> there is a default virtual host set up.  If there is a default,
> > then
> >> >> an unrecognized_name alert is sent with the warning level.  When
> no
> >> >> default is configured, the alert sent is fatal since the
> handshake
> >> >> can not continue.
> >> >>
> >> >> The warning lets the client know that there was not a match, but
> >> that
> >> >> the server can still continue using its default.
> >> >
> >> >
> >> > While this behaviour appears quite sensible/plausible, it will
> lead
> >> > to the behaviour in the wild that Yngve is reporting.
> >> >
> >> > An application which
> >> > does not configure any SNI characteristics, is not using SNI, and
> >> > for these, the server TLS implementation should _NOT_ be sending
> >> > SNI mismatch TLS alerts unless the application explicitly requests
> >> so.
> >>
> >> My server code will not send an alert unless the client (a) sent an
> >> SNI and (b) that SNI did not map to a virtual host.
> >>
> >> So that should not cause a problem.
> >>
> >> It might be a good idea to clarify when sending an unrecognized_name
> >> alert would be appropriate and clarify that it can be just a warning
> >> and what that means.
> >>
> >> Mike
> >> _______________________________________________
> >> TLS mailing list
> >> TLS@ietf.org
> >> https://www.ietf.org/mailman/listinfo/tls
> > _______________________________________________
> > TLS mailing list
> > TLS@ietf.org
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> >