[olug] SPAM, Viruses, and forged mail headers

[David Walker]

The dns lookups based on reverse dns only work when the domain admin is also 
the reverse dns admin.  This isn't always possible, especially for accounts 
on dsl, or dialup.

I'm not as concerned with spammers that own their own domain name.  If they 
own the domain name we have a contact point for them without having to do a 
lot of investigation.  We might actually have a chance of keeping some 
measure of control over them if they are forced to only use domains they own.

My proposal would limit the effectiveness of open relays.  If yahoo.com and I 
both adopt the system then I can automatically deny mail claiming to be from 
yahoo.com unless yahoo.com itself has the open relay.

Actually, since we can virtually guarantee that the system would be unlikely 
to reach 100% adoption, this is most effective at forcing spammers into using 
their own domains or domains that don't support this system and keeping 
people from injecting email into my system forged to appear as if it 
originated there.
(i.e.
From: The Boss <bossman at grax.com>
To: David Walker<olug_member at grax.com>
Subject: Termination

You are fired.
)

If we convinced yahoo, hotmail, and mail.com to use this system we could start 
reading mail from their domains again instead of dropping it in the spam bin.

On Wednesday 08 May 2002 03:00 pm, Nick Walter wrote:
> Hmm, interesting enough idea.  Some mail servers already can test for
> impersonation using DNS checks on the connecting address (both forward and
> reverse lookups) to make sure it's from the domain the e-mail claims to be
> from.  Unforunately, such restrictions are easily worked around by simply
> owning your own domain name and using something like dyndns to bounce
> around your DNS records quickly.  And a nice juicy open relay lets a
> spammer dodge all sorts of restrictions.
>
> Nick Walter
>
> -----Original Message-----
> From: David Walker [mailto:linux_user at grax.com]
> Sent: Wednesday, May 08, 2002 2:51 PM
> To: olug at olug.org
> Subject: [olug] SPAM, Viruses, and forged mail headers
>
>
> I came up with an idea, or at least the beginning of an idea, on how to
> stop header forgery in email.  If this works it could keep spammers from
> using domain names they do not have control of in their return addresses.
> (and some
> viruses that forge email headers would be stopped as well.)
>
> I would appreciate some feedback on my ideas at
> http://www.vorteon.com/papers/spam_reduction_through_dns.html
>
>
>
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For help contact olug-help at olug.org - run by ezmlm
to unsubscribe, send mail to olug-unsubscribe at olug.org
or `mail olug-unsubscribe at olug.org < /dev/null`
(c)1998-2002 OLUG http://www.olug.org

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