From mboxrd@z Thu Jan  1 00:00:00 1970
From: Georgi Alexandrov <tehlists@hotpop.com>
Subject: Re: Detecting/Defeating Spambots
Date: Tue, 07 Jun 2005 14:31:52 +0300
Message-ID: <42A585A8.3060001@hotpop.com>
References: <Pine.LNX.4.61.0506061244340.1874@UniXpress93.unixpress.com>
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Lucky Leavell wrote:

>OS: SuSE 9.3 Pro
>
>I work with a small ISP and we are encountering with increasing frequency 
>Windows machines which have been compromised and apparently being used as 
>spambots based on their attempted connection to port 25 of foreign hosts 
>instead on using our mail server for outgoing mail.
>
>With allowance for legitimate exceptions, could we simply disallow port 25 
>connections from within our networks to any but our mail servers? 
>
Yes, something like that:
iptables -A FORWARD -p tcp -s $our_networks -d ! 
$our_mail_server_ip_addr --dport 25 -j DROP

>(We run 
>all outgoing -as well as incoming- mail thru amavis/clamav/spamassassin.)
>
>Any other thoughts or links to resources?
>
>Thank you,
>Lucky
>
>
>  
>