[Pkg-openssl-devel] Bug#221689: Checking the existence of the bug.

[Artur R. Czechowski]

On Tue, Aug 01, 2006 at 06:03:30PM +0200, Kurt Roeckx wrote:
> But it does support 2 protocols, smtp and pop3.  It just doesn't
> support them very well.  I'm not not familiar with the smtp
> protocol enough to know what you can send STARTTLS.  exim4 above
> claims it wasn't advertised.  So I wonder when it gets
> advertised, and wether it supports it or not.
RFC 2821 contains a detailed ESMTP specification.
Summary about the case follows.

2821, Section 4.1.1.1:
    In any event, a client MUST issue HELO or EHLO before starting a mail
    transaction.

2821, Section 4.3.1:
    The communication between the sender and receiver is an alternating
    dialogue, controlled by the sender.  As such, the sender issues
    a command and the receiver responds with a reply.  Unless other
    arrangements are negotiated through service extensions, the sender MUST
    wait for this response before sending further commands.

    One important reply is the connection greeting.  Normally, a receiver
    will send a 220 "Service ready" reply when the connection is completed.
    The sender SHOULD wait for this greeting message before sending any
    commands.

So, it is sufficient to say, that EHLO/HELO must be issued before any other
command and the client must wait for answer before next command.

If you would dig more in 2821 you could find that any extension is available
only if advertised in greeting reply. So, client connects, greets with
EHLO and receives answer like:
250-blabluga.hell.pl 
250-SIZE 50331648
250-8BITMIME
250-PIPELINING
250-STARTTLS
250 HELP

The first line is greeting answer, next ones are extensions' advertisements.
More about it in 2821, Section 2.2: The Extension Model.

Additionaly, if you are curious :), in RFC 3207 you can find a STARTTLS
description.
    
Regards
	Artur
-- 
"Wyrzynarka jest lepsza od wibratora"
				/Socjonetka/