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Date:      Sun, 14 Jul 2002 09:36:00 +0200
From:      Bernd Walter <ticso@cicely5.cicely.de>
To:        Terry Lambert <tlambert2@mindspring.com>
Cc:        Gregory Neil Shapiro <gshapiro@FreeBSD.ORG>, freebsd-arch@FreeBSD.ORG
Subject:   Re: Mail subsystem defaults, adding authentication.
Message-ID:  <20020714073559.GY63545@cicely5.cicely.de>
In-Reply-To: <3D30C4DA.22A255A8@mindspring.com>
References:  <20020713034725.GB47677@ussenterprise.ufp.org> <3D2FAFB2.E2E9CF36@mindspring.com> <20020713045704.GA49379@ussenterprise.ufp.org> <3D300FD4.7479A8E5@mindspring.com> <15664.47827.844708.151118@monkeyboy.gshapiro.net> <3D30C4DA.22A255A8@mindspring.com>

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On Sat, Jul 13, 2002 at 05:24:59PM -0700, Terry Lambert wrote:
> > You can (and should) use STARTTLS with SMTP AUTH PLAIN/LOGIN and do not
> > (and should not) use SMTP over SSL as it is non-standard.
> 
> IMO, this is broken.  Here's why:  Implementation of SSL in the
> kernel is a foregone conclusion.  It is a matter of "when", not
> "if", due to work like that of Sam Leffler's recent porting of
> the OpenBSD crypto hardware interface framework to FreeBSD.
> 
> Basically, asking for conversion of a socket from one type to
> another is not something that will necessarily be supportable.

With SSL you still do a normal socket connect anyway and than
call SSL_connect/accept on the already existing connection.
What's the matter with exchanging packets before doing that?
Does that mean that the SSL API changes?

> The whole "STARTTLS" thing was introduced to kludge around the
> lack of IPSEC support in IPv4.  Even if you argue that it's an
> issue for IPv4 because IPSEC bloats the hell out of IPv4 even
> when it's not being used, IPv6 requires implementation of IPSEC
> for it to be called an IPv6 implementation.
> 
> This means that the days of transport crypto decisions like
> this one, and the code to implement it, living in user space
> are numbered, no matter what.

I'm not a cryptographic expert, but I wouldn't prefer a packet
encryption over a stream encryption.

> I know the sendmail folks don't like SMTP over SSL, but...
> there is an IANA assigned number in /etc/services for it,
> which makes it about as standard as it can be; I don't think
> SSL RFC policy requires a per protocol SSL usage RFC for SSL
> to be used (that wouldn't make sense, in terms of promoting
> the adoption of SSL).

With STARTTLS you can probe for SSL in MTA - MTA comunications.
MTAs connect foreign SMTP servers and want to prefer SSL.
It's unpractical to try a connect to smpts port first with all those
blackhole firewalls out there.
The only downside with STARTTLS is that it makes it allmost impossible
to use external SSL boxes.

-- 
B.Walter              COSMO-Project         http://www.cosmo-project.de
ticso@cicely.de         Usergroup           info@cosmo-project.de


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