From: Georgi Alexandrov <tehlists@hotpop.com>
To: netfilter@lists.netfilter.org
Subject: Re: Detecting/Defeating Spambots
Date: Tue, 07 Jun 2005 14:31:52 +0300 [thread overview]
Message-ID: <42A585A8.3060001@hotpop.com> (raw)
In-Reply-To: <Pine.LNX.4.61.0506061244340.1874@UniXpress93.unixpress.com>
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
>
>
>
>
next prev parent reply other threads:[~2005-06-07 11:31 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-06-06 16:49 Detecting/Defeating Spambots Lucky Leavell
2005-06-07 11:31 ` Georgi Alexandrov [this message]
2005-06-07 11:36 ` Georgi Alexandrov
2005-06-07 11:51 ` Georgi Alexandrov
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