Re: IETF mail server and SSLv3

[Phillip Hallam-Baker <[e-mail]>]

On Fri, Feb 5, 2016 at 4:10 PM, John Levine <[e-mail]> wrote:
>>The issue at hand is whether or not to disable the use of old ciphersuites in
>>the IETF's use of STARTTLS in SMTP. Irrespective of the reasons we have for
>>doing that, John's point was and is that it can adverse effect on our ability
>>to reach everyone who wants to participate.
>
> Has anyone looked at the logs to see how much SSL3 there actually is?
> In my logs, which are doubtless not representative of anyone but
> they're what I've got, here's what I see for the past six weeks of
> starttls on my IPv4 server:
>
> 22617 TLS1.2/X.509/AEAD
> 16791 TLS1.0/X.509/SHA1
> 2526 TLS1.2/X.509/SHA256
> 2069 TLS1.2/X.509/SHA384
> 1058 TLS1.2/X.509/SHA1
>  339 TLS1.1/X.509/SHA1
>  232 SSL3.0/X.509/SHA1
>  147 TLS1.0/X.509/MD5
>    8 TLS1.0/X.509/SHA256
>
> And here's the past year on my lower volume IPv6 server:
>
> 130886 TLS1.2/X.509/AEAD
> 44172 TLS1.0/X.509/SHA1
> 6610 TLS1.2/X.509/SHA1
> 1485 TLS1.1/X.509/SHA1
>  259 TLS1.2/X.509/SHA384
>
> (The much higher numbers are mostly because gmail sends all their mail
> to me over IPv6 with TLS.)
>
> I was surprised to see 237 SSL3 connections, so I looked at the ones
> in the past day, all of which are from two servers on a network in
> Turkey running ancient versions of Merak, and trying to send me spam.
> One is sending spam from the bogus domain globalconferences.org (no A,
> AAAA, or MX record) presumably for fake conferences.  So at least
> here, rejecting SSL3 would only block a little spam.

I would be surprised by any legitimate SSL3 mail because the STARTTLS
spec came long after TLS 1.0 was settled.

There might be a mail server out there that cannot legitimately do TLS
but I would be very surprised. And any server that can't accept
TLS/1.0 inbound isn't compliant with the spec anyway.