FW: [EXIM] Spam relay fighting, help!

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Autor: Ring, John C
Data:  
A: Exim User's List (E-mail)
Assumpte: FW: [EXIM] Spam relay fighting, help!
>On Mon, 15 Dec 1997, Ring, John C wrote:
>
>> I'm having a bit of trouble stamping out relaying. I'm using Exim
>> version 1.73 #1 built 12-Dec-1997 09:13:38.
>
>Note that 1.80 was released on December 9th.


I was at 1.61 before upgrading :) If it ain't broke...

>> When I first tested my configuration, all appeared well with my

tests.
>> However, it appears someone's found a trick for Exim, at least with

my
>> current config, to relay email. Apparently, simply putting
>>
>> TO: --.--@switch.com
>>
>> after the DATA statement is causing Exim to actually send messages

with
>> non-local RCPT TO addresses.
>
>That seems odd, since it checks out (and responds to) the incoming RCPT
>TO before it ever sees the DATA statement. Consequently, I think

there's
>>something else going on here.


I thought it was rather odd myself, but that's what appears to be going
on.

>> The relevant lines, I think, from our Exim
>> configure file is:
>>
>> LOCAL_NETS = <list of local networks, firewall network excluded>
>> relay_domains = *switch.com
>> sender_net_accept_relay = LOCAL_NETS
>>
>> Note that the Exim machine sits behind a firewall with will accept

any
>> message, but will simply forward it to the Exim machine for actual
>> sending.
>
>What addresses are getting through? Have you got copies of the headers
>of any of these messages?


Yes, here's a message forwarded to me.

Return-Path: <aP6LQU3vV@???>
Received: from bulwark.switch.com (bulwark.switch.com [206.181.77.34])
    by camel9.mindspring.com (8.8.5/8.8.5) with ESMTP id DAA26132
    for <eguy@???>; Mon, 15 Dec 1997 03:16:34 -0500 (EST)
From: aP6LQU3vV@???
Received: by bulwark.switch.com; id DAA26334; Mon, 15 Dec 1997 03:13:04
-0500 (EST)
Received: from hdn94-005.hil.compuserve.com(206.175.101.5) by
bulwark.switch.com via smap (3.2)
    id xmamf5431; Mon, 15 Dec 97 03:12:50 -0500
DATE: 15 Dec 97 3:15:52 AM
Reply-to: Style2000@???
Message-ID: <MV5Yl>
Received: From mailhost.aol.com(alt1.aol.com(151.5.18.21)) by
aol.com;Mon, 15 Dec 1997 3:15:52 -400 (EDT)
TO: --.--@switch.com
SUBJECT: Are You In Need Of A Lifestyle Change...?


In my testing, before I wrote this message, I tried to send a message to
this list manually from our firewall. From my logs, Exim did block it.
However, after I send this message, I'll do the same thing, but add the
TO: --.--@switch.com in the DATA section, and see if it reaches the
list.

> telnet mail1 25
> Trying 192.65.179.9...
> Connected to proxy2.switch.com.
> Escape character is '^]'.
> 220 mail-smtp.switch.com ESMTP Exim 1.73 #1 Mon, 15 Dec 1997 11:06:53
> -0500
> mail from: <jcring@???>
> 250 <jcring@???> is syntactically correct
> rcpt to: <exim-users@???>
> 550 relaying to <exim-users@???> prohibited by
> administrator
> data
> 354 Enter message, ending with "." on a line by itself
>
> Will this make it to the list? I wonder!


--
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