Subject: RE: [Asrg] Re: Asrg digest, Vol 1 #133 - 14 msgs

From: "Sauer, Damon" <[email-masked]>
Date: Fri, 28 Mar 2003 11:30:34 -0500

>> The problem such a facility solves is to make spam forgery more
difficult,
>
>No, not really.
>What is the probability to fake <name>@hotmail.com or <[email-masked]>
>and get a hit? I'd say if you do it halfway intelligent it's about 98%.
>So you get mail from
>    [email-masked]
>it gets verified by hotmail.com as existant.
>What exactly help in this situation to eliminate spam?

 ----- It makes the sending server legitimate. This is the number one thing
that needs to be addressed.

	There are some very smart people participating, but like most smart
people, we are trying to over design it.

 	I submit to you that there will never ever be a way to stop someone
from sending spam if they really wanted to. What needs to happen is making
this process as difficult as possible and making the true source
*accountable* for the email that they send. 

	Let's break spam and not SMTP. The more difficult it is for a
spammer to send spam successfully to valid addresses, the lower the return
for the spammer. Eventually the economic model for UCE will be broken and
you will only get two types. Spam from people with deep pockets and
*legitimate* offerings.

	After you legitimize the source of the email, everything else is an
administration issue.

How do we do this?
 
 A reverse DNS (rDNS) lookup.

 eg.

<< HELO 90.67.80.1
>> Sending server has a valid A or MX record.
<< mail from: [email-masked]
>> rDNS lookup of YAHOO.com RMX record shows that the IP address 90.67.80.1
is not a member of any of its mail servers' SUBNETS.
<< 550 Spam-B-Gone 

 The RMX record will either be a subnet in the case of multiple mta's,
multiple subnets in the case of multiple MTA's on different subnets or a
single IP address for domains with only one MTA. Listing all the specific IP
addresses for all MTA's that a host owns is cumbersome and unnecessary.

What does this mean for the following example:

<< HELO 90.67.80.1
>> Sending server has a valid A or MX record
<< mail from: [email-masked]
>> rDNS lookup of pornspam.com RMX record shows that the IP address of
90.67.80.1 IS a member of its mail servers' subnets.
>> Ok- Send your email.

Yes.. that is right, the spam is coming. The HUGE difference here is that I
can block the RMX record of the domain, that will block ALL of the spammers
subnets or single MTA, whatever the case may be. I can now block the IP,
hostname, domain name, etc without fear of it being forged. I realize that
DNS can be forged, but this runs into 2 problems for a spammer... he is now
subject to federal criminal laws and faces potential long prison sentences
and huge fines and he must do many technical things first before he can
start spamming, which breaks the economic model or spam. It also removes
Joe-the-plumber as a spammer because he is no longer able to just let it fly
when he is at work. Right now, spamming requires no real special skills. How
many spammers and how much spam did I just kill?

	Now that I have killed all the untechnical spammers and the spoofing
spammers, I can now concentrate on what is left.
	How do I deal with those- RBLS, pressure on the ISP (because we now
know it is *really* coming from them), new or improved laws (I realize that
this does not scare a relay owner in Japan, but when was the last time you
received a spam asking you to pay up in YEN?!). My point is that even though
they are relays, the money is here. Since the amount of spam has been
drastically reduced, this leaves investigators free to concentrate on the
big guys.

 Ok.. What did I just say-

 You do not need to over design anything. Legitimize email and make it
difficult to spam. Destroy the economic model. Resolve other issues through
administration and tools. Send the big guys to court... Whether it be
criminal court or bankruptcy court, the outcome is the same. Force ISP's to
mend their ways. Spam *problem* resolved.

Regards,
Damon

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---

From: "Sauer, Damon" <[email-masked]>
Date: Fri, 28 Mar 2003 14:49:11 -0600

>> It wouldn't even reduce the amount of spam.
>> Is it just me or why do I get the impression that a lot of 
>> people think
>> that spammers are dumb idiots and that telling them "nanana, you can't
>> do this anymore" will change a thing?

>Lightweight authentication by IP address will reduce the amount
>of spam in the short term. In most part the same way that car
>alarms reduce the chance that YOUR car is the one stolen.

--- I can tell you that when we added LDAP to our 821 process, the volume of
spammers actually trying to make connections dropped by over 1/2 and has
stayed down since Sept of last year. Real world example of just saying
"nanana" actually reduces over-all spam connection load.

Regards,
Damon

*****

---

From: "Hallam-Baker, Phillip" <[email-masked]>
Date: Fri, 28 Mar 2003 14:28:27 -0800

OK run a DNS server on a dynamic address.

i don't think dynamic DNS is quite THAT dynamic yet.

	Phill
> -----Original Message-----
> From: [email-masked] [mailto:[email-masked]]
> Sent: Friday, March 28, 2003 5:12 PM
> To: Hallam-Baker, Phillip
> Cc: [email-masked]
> Subject: Re: [Asrg] Re: Asrg digest, Vol 1 #133 - 14 msgs 
> 
> 
> On Fri, 28 Mar 2003 12:45:29 PST, "Hallam-Baker, Phillip" said:
> 
> > The only Internet protocol that requires a static IP 
> > address is DNS.
> 
> Even that isn't totally true.
> 
> 2136 Dynamic Updates in the Domain Name System (DNS UPDATE). P. Vixie,
>      Ed., S. Thomson, Y. Rekhter, J. Bound. April 1997. 
> (Format: TXT=56354
>      bytes) (Updates RFC1035) (Updated by RFC3007) (Status: PROPOSED
>      STANDARD)
> 
> Even the NS RR can point at a dunamic address if you play 
> games with the TTL ;)
>