Subject: RE: [lemonade] Comments on PUSH and PULL drafts

From: "Vaudreuil, Greg M (Greg)" <[email-masked]>
Date: Wed, 3 Mar 2004 16:43:36 -0600

Thanks to all who have responded on this point... call me more fully educated and now convinced that submission authentication is moving towards being the norm.

I have also been convinced that my concern about authenticating the Submit path without granting access to the credential database to the submission server in the DMZ can be securely addressed in a number of ways, so I withdrawal that objection as well.

On to the next issues.

Greg V.

-----Original Message-----
From: Steve Hole [mailto:[email-masked]]
Sent: Thursday, March 04, 2004 7:01 AM
To: Vaudreuil, Greg M (Greg)
Cc: Mark Crispin; Rob Siemborski; Marcus D. Leech; [email-masked]
Subject: RE: [lemonade] Comments on PUSH and PULL drafts

On Tue, 2 Mar 2004 15:21:40 -0600  "Vaudreuil, Greg M (Greg)" 
<[email-masked]> wrote:

> 
> While submission servers can and should authenticate using per-user 
> credentials, this still seems to be an operational exception rather than 
> the rule.  The Pull proposal counts upon operational behavior change 
> here, and I am not yet convinced that it is reasonable.

The whole thing is an operational change Greg.  Beside, Sendmail has had 
SASL support for a long time now with all of the appropriate semantics for
doing relay forwarding in authenticated state.   Lot's of people use it 
that way for that purpose alone.

This generalization that few people are doing this way is debatable at the
very least. 

---
Steve Hole
Chief Technology Officer - Billing and Payment Systems
ACI Worldwide
<mailto:[email-masked]>
Phone: 780-424-4922

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---

From: Randall Gellens <[email-masked]>
Date: Tue, 2 Mar 2004 15:51:17 -0800

At 4:20 PM -0600 3/2/04, Greg M (Greg) Vaudreuil wrote:

>  Again, it may be possible to support this with an SMTP-level 
> protocol proxy, but if I already have an IMAP-level proxy, then I'd 
> rather re-use it.  And of course, Ned loves to tell stories about 
> how brain-dead SMTP proxies have made the world a better place :-( 
> I'm sure you can tell stories of why IMAP proxies are equally 
> nasty.  Maybe we can agree that one of these things is better than 
> two?

I think that basing an important technical decision on the issue of 
one versus two proxies (in the rather special case of those who 
deploy proxies) would be a mistake.
-- 
Randall Gellens
Opinions are personal;    facts are suspect;    I speak for myself only
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Man is a rational animal who always loses his temper when he is
called upon to act in accordance with the dictates of reason.
                                                  --Oscar Wilde

---

From: Randall Gellens <[email-masked]>
Date: Tue, 2 Mar 2004 15:48:41 -0800

At 3:21 PM -0600 3/2/04, Greg M (Greg) Vaudreuil wrote:

> credentials, this still seems to be an operational exception rather 
> than the rule.  The Pull proposal counts upon operational behavior 
> change here, and I am not yet convinced that it is reasonable.

Not every organization or ISP will update to what we produce, 
regardless of push versus pull.  However, I do see increasing use of 
authenticated submission, especially from ISPs, because it solves the 
mobile user problem.

>  One possible example:
>
>   - For ISP's and the like, the submit server lives in a DMZ-like 
> environment where there are requirements to limit access to 
> sensitive data like user credentials. It is more "secure" from some 
> perspectives to authorize based on source IP address (is it on my 
> network) than to expose and use per-user authentication. Here 
> anti-spam and authentication database protection are somewhat at 
> odds.

The submit server can authenticate users without risking exposure of 
the credentials.  For example, the submit server can use 
challenge/response, and pass the data to a AAA or LDAP server for 
validation.

But the issue is even worse for pull, because then the entire IMAP 
server must be in the DMZ, and hence can compromise all user data. 
(If you want to argue proxies in the DMZ, that applies to IMAP and to 
submission servers.)

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