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Re: OpenSSL disables TLS 1.0 and 1.1




On Fri, Aug 11, 2017 at 08:41:10AM -0400, Wouter Verhelst wrote:
> On Mon, Aug 07, 2017 at 08:35:52PM +0200, Kurt Roeckx wrote:
> > On Mon, Aug 07, 2017 at 05:22:51PM +0200, Joerg Jaspert wrote:
> > > I wonder if there is a middle way that ensures that all new stuff does
> > > go TLS1.2 (or later, whenever), but does allow older stuff still to
> > > work. Which isnt the case if they are just disabled.
> > 
> > I could change the default settings to set the minimum supported
> > version as TLS 1.2. That is, act like
> > SSL_CTX_set_min_proto_version() was called with TLS1_2_VERSION.
> > That would allow applications to override this this by calling
> > SSL_CTX_set_min_proto_version(). But then those are new
> > functions in 1.1.0 and they probably aren't supported by many
> > applications.
> > 
> > An other alternative is to use the deprecated SSL_CTX_set_options
> > options (SSL_OP_NO_TLSv1 | SSL_OP_NO_TLSv1_1) by default, but then
> > there is probably no software that has support for clearing those
> > with SSL_CTX_clear_options()
> 
> Would it instead be possible to create an item in the openssl.conf file
> to disable TLS1.2 by default? That way, users can re-enable TLS1.{0,1}
> in cases where that's required, and you can drop TLS1.0 and 1.1 (and
> possibly 1.2 even, if 1.3 has enough traction) in bullseye.

I prefer this to be enabled on application basis, which is why I
suggested the above ways.

OpenSSL has support for setting such a mimimum in a config file,
I'm just not sure if it reads any section related to it by
default, I think it doesn't.


Kurt