Re: STARTTLS & EHLO
John C Klensin <john+smtp@jck.com> Thu, 29 January 2009 15:54 UTC
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Date: Thu, 29 Jan 2009 10:53:49 -0500
From: John C Klensin <john+smtp@jck.com>
To: Tony Hansen <tony@att.com>, ietf-smtp@imc.org
Subject: Re: STARTTLS & EHLO
Message-ID: <37F39FF37390694B69567838@PST.JCK.COM>
In-Reply-To: <4981C6BD.2040900@att.com>
References: <497DE492.4080506@pscs.co.uk> <497DED29.70402@att.com> <497ED420.30708@pscs.co.uk> <alpine.LSU.2.00.0901271403220.4546@hermes-2.csi.cam.ac.uk> <497F86CB.60904@att.com> <alpine.LSU.2.00.0901281434440.4546@hermes-2.csi.cam.ac.uk> <498088B8.9040404@pscs.co.uk> <alpine.LSU.2.00.0901291310080.4546@hermes-2.csi.cam.ac.uk> <4981C0D5.1010401@pscs.co.uk> <4981C6BD.2040900@att.com>
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--On Thursday, January 29, 2009 10:09 -0500 Tony Hansen <tony@att.com> wrote: > If this is the interpretation that we gain consensus on, that > it means "start over from scratch", it might as well also say > that it > > SHOULD only be executed immediately after the initial EHLO. > > The only possible exceptions to this rule would be for verbs > that don't affect the state machine, such as VRFY, EXPN, HELP, > NOOP. RSET is also harmless immediately after EHLO. Changing the state from "session open (EHLO issued), no mail transaction state" to "session open (EHLO issued), no mail transaction state" is a no-op. And the first paragraph of 4.1.1.5 of 5321 says that. Out of context, I'm not sure exactly what you are suggesting above, but I believe that it would mean: S: 220 ... C: EHLO ... S: 250-... S: 250-STARTTLS S: 250-... S: 250 OK C: STARTTLS ... (TLS session starts) and the next command must be either EHLO or as many instances of any of VRFY, EXPN, HELP, NOOP, RSET as desired, followed by EHLO Also, the "what the server MUST (or SHOULD) discard and the client MUST (or SHOULD) not depend on" sentences and example might reasonably be modified to explicitly include any information gained from VRFY or EXPN issued between the 220 greeting and the initial EHLO. While one might not trust VRFY or EXPN queries or results issued under TLS either, it would be pointless and silly to send them before the initial EHLO if one knew that one was going to issue STARTTLS if the server permitted it. Indeed the only reason for doing so would be if one intended to make a decision about whether to continue with a mail transaction at all based on the results of VRFY or EXPN... and that would be very rare today except in special circumstances. john
- Re: STARTTLS & EHLO: Errata text? Hector Santos
- Re: STARTTLS & EHLO: Errata text? Tony Finch
- Re: STARTTLS & EHLO: Errata text? Hector Santos
- Re: STARTTLS & EHLO: Errata text? ned+ietf-smtp
- Re: STARTTLS & EHLO: Errata text? Tony Finch
- Re: STARTTLS & EHLO: Errata text? Tony Finch
- Re: STARTTLS & EHLO: Errata text? Tony Finch
- Re: STARTTLS & EHLO: Errata text? Russ Allbery
- Re: STARTTLS & EHLO: Errata text? ned+ietf-smtp
- Re: STARTTLS & EHLO: Errata text? SM
- Re: STARTTLS & EHLO: Errata text? Hector Santos
- Re: STARTTLS & EHLO: Errata text? John C Klensin
- Re: STARTTLS & EHLO: Errata text? Paul Smith
- Re: STARTTLS & EHLO: Errata text? Paul Smith
- Re: STARTTLS & EHLO Tony Hansen
- Re: STARTTLS & EHLO: Errata text? Russ Allbery
- Re: STARTTLS & EHLO: Errata text? Hector Santos
- Re: STARTTLS & EHLO: Errata text? ned+ietf-smtp
- Re: STARTTLS & EHLO: Errata text? John C Klensin
- Re: STARTTLS & EHLO: Errata text? Hector Santos
- Re: STARTTLS & EHLO: Errata text? ned+ietf-smtp
- Re: STARTTLS & EHLO: Errata text? Alexey Melnikov
- Re: STARTTLS & EHLO: Errata text? Alexey Melnikov
- Re: STARTTLS & EHLO: Errata text? SM
- Re: STARTTLS & EHLO: Errata text? ned+ietf-smtp
- Re: STARTTLS & EHLO: Errata text? Hector Santos
- Re: STARTTLS & EHLO: Errata text? Bill McQuillan
- Re: STARTTLS & EHLO: Errata text? John C Klensin
- Re: STARTTLS & EHLO: Errata text? SM
- Re: STARTTLS & EHLO: Errata text? Alexey Melnikov
- Re: STARTTLS & EHLO: Errata text? Tony Hansen
- Re: STARTTLS & EHLO John C Klensin
- Re: STARTTLS & EHLO Tony Hansen
- Re: STARTTLS & EHLO Paul Smith
- Re: STARTTLS & EHLO Tony Finch
- Re: STARTTLS & EHLO Hector Santos
- Re: STARTTLS & EHLO SM
- Re: STARTTLS & EHLO John C Klensin
- Re: STARTTLS & EHLO Tony Hansen
- Re: STARTTLS & EHLO Peter Bowyer
- Re: STARTTLS & EHLO Hector Santos
- Re: STARTTLS & EHLO Paul Smith
- Re: STARTTLS & EHLO Tony Finch
- Re: STARTTLS & EHLO Paul Smith
- Re: STARTTLS & EHLO John C Klensin
- Re: STARTTLS & EHLO Tony Hansen
- Re: STARTTLS & EHLO Tony Finch
- Re: STARTTLS & EHLO Alessandro Vesely
- Re: STARTTLS & EHLO Paul Smith
- Re: STARTTLS & EHLO Alexey Melnikov
- Re: STARTTLS & EHLO Tony Finch
- Re: STARTTLS & EHLO John C Klensin
- Re: STARTTLS & EHLO Tony Hansen
- STARTTLS & EHLO Paul Smith
- Re: STARTTLS & EHLO: Errata text? SM
- Re: STARTTLS & EHLO: Errata text? Hector Santos
- Re: STARTTLS & EHLO: Errata text? SM
- Re: STARTTLS & EHLO: Errata text? Hector Santos
- Re: STARTTLS & EHLO: Errata text? John C Klensin
- Re: STARTTLS & EHLO: Errata text? Tony Finch
- RFC 1123bis? Hector Santos
- Re: STARTTLS & EHLO: Errata text? John C Klensin
- Re: STARTTLS & EHLO: Errata text? Hector Santos
- Re: STARTTLS & EHLO: Errata text? John C Klensin
- Re: STARTTLS & EHLO: Errata text? Tony Finch
- Re: STARTTLS & EHLO: Errata text? SM