On 6/14/02 6:23 AM, Pam Lefkowitz deftly typed out:

> Return-Path: <[EMAIL PROTECTED]>
> Received: from $domain ([63.87.117.9])
>   by thrush (EarthLink SMTP Server) with SMTP id 17iKsbCO3NZFoB0
>   for <[EMAIL PROTECTED]>; Thu, 13 Jun 2002 23:20:57 -0700 (PDT)
> From: [EMAIL PROTECTED]
> X-Encoding: MIME
> Received: from corecomputing.com by 22499U.corecomputing.com with SMTP for
> [EMAIL PROTECTED]; Fri, 14 Jun 2002 02:25:52 -0500

This is how I read the above headers (bottom up).

A message is received from a machine calling itself "corecomputing.com"
(it's not) by a host calling itself "22499U.corecomputing.com" (it's not)
and the receiving host stamps the first Received header on the message. The
host that calls itself 22499U.corecomputing.com passes the message on to
your mail server, an Earthlink server (I'm assuming they are hosting your
domain). Earthlink's mail server then stamps the second Received header
indicating the IP of the host it received the message from (63.87.117.9)
which is the machine that actually sent the spam.

Most likely corecomputing.com and 22499U.corecomputing.com are the same host
which is running some software to spoof the hostname in the first Received
header by using a hostname that is equal to the domain part of your email
address ([EMAIL PROTECTED] produces a host corecomputing.com). My theory
is further reinforced by the fact that the software seems misconfigured and
that the host in question identified itself as "$domain" (a variable name,
not a hostname). 

You can further track the bugger down by typing:

whois -h whois.arin.net 63.87.117.9

At the command line (Since you're using OS X). This will query the ARIN
database for the organization that the IP address is assigned to. If the
result indicates that the IP space in question has been reassigned or if it
is outside of ARIN's control (Managed by APNIC, RIPE, etc.) you may have to
replace whois.arin.net with the appropriately listed whois or rwhois server.
If it is an rwhois server, there's a web interface to rwhois at
<http://www.rwhois.net/rwhois/prwhois.html>. Eventually you can drill down
to the ISP that is responsible for that IP address and either the
whois/rwhois answer or the ISP's website will indicate an email address to
report network abuse to.

I manage a couple of mail servers and this little exercise has become my
favorite idle time activity. If I track the IP space to a company selling
marketing services I just block their whole IP space at the mail server.

-Remo Del Bello

-- 
Do not meddle in the affairs of sysadmins, for they are subtle and quick to
anger.


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