Full Disclosure mailing list archives

Re:Proposal: how to notify owners of compromised PC's


From: Thomas Zangl - Mobil <mobil () tzis net>
Date: Wed, 28 Jan 2004 21:20:24 +0100

 
Am Wed, 28 Jan 2004 18:36:34 +0000, schrieb petard <petard () freeshell org>:

Hi,

I left my ISP about 9 months ago because they implemented this very
policy. It entirely destroyed my ability to send email from my preferred
address. Our SMTP setup at example.com relays mail from people
claiming to be @example.com if and only if they have been authenticated
using a client X.509 certificate issued by the example.com root
certificate authority. The mechanism for achieving this is to connect to
smtp.example.com, port 25, and use the STARTTLS command after the EHLO,
as described in RFC 3207. The policy you describe broke this, and
therefore prevented me from sending mail to my cohorts at example.com.
The ISP would not make an exception, so I left. I was not the only one.

As I said before, the ISP _HAS_ to provide an alternative mail relay, open
for every FROM address the user whishes to use. (If it´s legal or not thats
another point). If you really need access to YOUR smtp server, it should
be possible to configure your MTA to listen to an alternative port than
25 too. I use this kind of setup for myself as I´m "smtp firewalled" the
way I´ve described above.

The benefit (in my opinion) would be greater, in my enviroment, then the
loss of freedom individual users will suffer. In case of static IP´s ISPs might
be able to offer exceptions.

--
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,yours Thomas Zangl -thomas () tzi dhs org- -TZ1-6BONE-
-http://tzi.dhs.org - http://www.borg-kindberg.ac.at
Use YAMC! now! Get it at http://www.borg-kindberg.ac.at/yamc/

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