[CentOS] Sendmail SMTP Brute-Force Attack

[Ross Walker]

If you have disabled open relaying then I would look at grey listing and throttling to reduce the number of spam per hour that comes in.

Since your routing others emails there is no point in spam analysis cause your customers are probably doing it already. Just need to dissuade spammers from full throttling your edge severs.

-Ross


On Jun 14, 2012, at 8:58 PM, Gustavo Lacoste <gustavo at lacosox.org> wrote:

> The problem with my server is: I use it to offer webhosting services. Some
> customers using Outlook are blocked because they use black listed ips (ips
> simply are dynamic).
> 
> 
> 
> With Kind Regards,
> 
>     Gustavo A. Lacoste Z.
>     Curacautín - Chile
>     Skype: knxroot
>     Msn & Gtalk: knx.root [at] gmail.com
>     Home page: http://www.lacosox.org
> - -
> *Por favor, evite enviarme documentos adjuntos en formato Word o PowerPoint.
> Lea http://www.gnu.org/philosophy/no-word-attachments.es.html*
> 
> 
> 2012/6/14 John R Pierce <pierce at hogranch.com>
> 
>> On 06/14/12 4:33 PM, Gustavo Lacoste wrote:
>>> I need help for STOP this spamers right now.
>>> 
>>> Thanks in advance to anyone who can guide me
>> 
>> 2 of the three relay IPs listed in your log fragment are listed on
>> spamhaus' Zen combined list, http://www.spamhaus.org/zen/
>> 
>> this is free for use by low volume non-commercial email servers. see the
>> terms linked on the above URL.
>> adding the following line to your sendmail.mc file, then rebuilding the
>> .cf and restarting sendmail would reject all mail connections from
>> servers listed via Spamhaus.
>> 
>> FEATURE(dnsbl,`zen.spamhaus.org',`Message from $&{client_addr} rejected
>> - see http://www.spamhaus.org/SBL/sbl-rationale.html') dnl
>> 
>> 
>> (note this file is in M4 syntax, and has to use 'funny' quoting, with a
>> ` as the opening quote).
>> 
>> 
>> 
>> 
>> 
>> --
>> john r pierce                            N 37, W 122
>> santa cruz ca                         mid-left coast
>> 
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