Order of protocols in MinProtocol

Klaus Umbach klaus+ml.openssl-users at uxix.de
Wed Jul 8 16:48:24 UTC 2020

On 08.07.20 12:21, Viktor Dukhovni wrote:
> On Wed, Jul 08, 2020 at 04:36:55PM +0100, Matt Caswell wrote:
> > On 08/07/2020 16:28, Viktor Dukhovni wrote:
> > >> How could I set the a System default "MinProtocol" for DTLS and TLS to 1.2?
> > > 
> > > AFAIK, that's not presently possible.  You can specify application
> > > profiles, for applications that specify an application name when
> > > initializing OpenSSL.  Or use the OPENSSL_CONF environment variable to
> > > select an alternative configuration file for DTLS applications.
> > 
> > Arguably, that is a bug. You *should* be able to do that - perhaps based
> > on some sensible mapping between TLS protocol versions based on whether
> > we have a DTLS or TLS based SSL_METHOD.

Should I open an issue at https://github.com/openssl/openssl/issues?

> I agree that the situation with MinProtocol in openssl.cnf is
> unfortunate.  But instead of mappings, I would propose a different
> solution:
>     * Restrict MinProtocol/MaxProtocol to just TLS protocols,
>       i.e. SSL_CTX objects with a TLS-based method.
>     * Introduct new controls: DTLSMinProtocolDTLS, DTLSMaxProtocol,
>       that are similarly restricted to SSL_CTX objects with a DTLS-based
>       method.
>     * Since SSL_CTX_new() takes a required method argument, we are in
>       never in doubt as to which pair of controls to apply to a given
>       context.
> Thoughts?

To me this sounds sane.

But for my personal problem right now (openconnect uses TLS and DTLS, so
even if it would set an application name I couldn't set a "proper"
setting), until this bug is fixed, I use this now:

   # MinProtocol = TLSv1.2
   Protocol = -TLSv1, -TLSv1.1, TLSv1.2, TLSv1.3, DTLSv1.2

(with a big comment for future-me, why I did something, that i shouldn't)

To my understanding, this will do exaclty what I want, up to that point in
time, when there are newer versions of DTLS and/or TLS supported and I want
to use them. (SSL3 is not supported in my build)

Am I right?


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