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Re: [ietf-smtp] SMTP Over TLS on Port 26 - Implicit TLS Proposal

2019-01-08 20:10:05

Oh? In what way is it "pretty good"?  Yes, SMTPS would hide the initial 220
message, the EHLO and the response - but there's no info in those two that
aren't already known after the 3-packet handshake and a few DNS PTR queries
or obtained by other means - you're going to have  a really hard time
claiming
that things like 8bitmime being advertised in the EHLO reply constitute
sensitive info.


Not every PTR queries resolves to the correct domain.

74.125.129.26 => jm-in-f26.1e100.net (A google IP address, but point to a
different domain owned by google)

I would be ok with indirectly someone getting the info rather than directly
providing it.


On Wed, Jan 9, 2019 at 7:27 AM Mark Andrews <marka(_at_)isc(_dot_)org> wrote:



On 9 Jan 2019, at 12:42 pm, Viruthagiri Thirumavalavan 
<giri(_at_)dombox(_dot_)org>
wrote:

You just invalidated all my arguments even though I provided sources.

So let me try in a different way.

If you think DNSSEC is so simple and not controversial, why do we need
MTA-STS?

The simple answer is WE DO NOT *NEED* MTA-STS.  Additionally it can be
spoofed
without DNSSEC.  The only thing it does is reduce the number of players
involved
if you are not self hosting.

On Wed, Jan 9, 2019, 7:02 AM Mark Andrews <marka(_at_)isc(_dot_)org wrote:


On 9 Jan 2019, at 11:30 am, Viruthagiri Thirumavalavan <
giri(_at_)dombox(_dot_)org> wrote:

@Mark Andrews

First, When I mentioned "The former requires a HTTPS server and the
latter requires DNSSEC.", I didn't mean DNSSEC is HARD to implement. I
meant DNSSEC is CONTROVERSIAL

Read some of these articles.

https://sockpuppet.org/blog/2015/01/15/against-dnssec/

A whole heap of half truths and poor analysis.  If that was presented as
a peer reviewed article it would not be published.  You have been had if
you believe that blog post.


https://www.theregister.co.uk/2016/02/23/dnssec_more_problem_than_solution/

“Oh Dear, Big Responses, The World is Going To End!!!!!”.  This is click
bait journalism.  We have standard track RFCs which provide the equivalent
of TCP’s three way handshake for DNS/UDP.  This has been deployed for 4+
years now along with other measures for clients that don’t implement the
RFC.  8% of the TLD servers currently implement that RFC.  It is on by
default in all current implementations of BIND (both client and server
side) and with the exception of a handful of (non RFC compliant) servers it
causes no issues.

Second, unless top domains like Google, Facebook etc. start to use
DNSSEC, you are gonna see questions like this.


https://security.stackexchange.com/questions/21121/if-dnssec-is-so-useful-why-is-its-deployment-non-existent-for-top-domains

28171 of 895949 zones which gave good answers from the alexa to 1M are
signed based on the run I started 2018-12-23T00:00:05Z.  The EDNS
compliance testing I do also reports whether the returned result is signed
(ok,yes) or not (ok).

% awk '$13 ~ /signed=ok,yes/ {yes[$1] = 1} $13 ~ /signed=ok/ { ok[$1] =
1} END { print length ( yes ) , length ( ok ) } '
reports/alexa1m.2018-12-23T00:00:05Z
28171 895949
%

So if you wanna convince others to use DNSSEC, you should start with
big brothers like Google.

Third, Yes DNSSEC is HARD. Maybe not for you. [You seem like a person
who knows your stuff]

No it isn’t.  In Unbound it is a checkbox where the server generates the
DNSKEYs and choosing the algorithm.  Are you saying ticking a checkbox is
HARD?  There TLD’s with +70% of the delegated zones signed.  You don’t get
to that level with “DNSSEC is HARD”.  The only reason DNSSEC is not
deployed more is COMPLACENCY and FEAR OF SOMETHING NEW.

Neither if these reasons == HARD.

We are talking about mail servers here. Many of these users are
non-tech savvy users who depends on third-party mail hosting services like
G-Suite.

Which almost certainly are using STARTTLS today and maybe using DANE
today as well on the outbound side.

As an engineer you can do those stuffs easily. But a doctor can't do
that. Just because he can't configure DNSSEC doesn't mean he don't deserve
security

And he can get DNSSEC today.  There are DNS hosting providers that will
do DNSSEC.  Almost all the
TLDs support DNSSEC.  There are DNS hosting providers that turn DNSSEC
ON BY DEFAULT.  Arguing that you can’t deploy a DNSSEC signed zone today
even as a lay person doesn’t bear up to scrutiny.

Mark
--
Mark Andrews, ISC
1 Seymour St., Dundas Valley, NSW 2117, Australia
PHONE: +61 2 9871 4742              INTERNET: marka(_at_)isc(_dot_)org


--
Mark Andrews, ISC
1 Seymour St., Dundas Valley, NSW 2117, Australia
PHONE: +61 2 9871 4742              INTERNET: marka(_at_)isc(_dot_)org



-- 
Best Regards,

Viruthagiri Thirumavalavan
Dombox, Inc.
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