sendmail greet_pause feature

[Roger Jochem]

To late...

I'm allready upgraded to 8.13 using the sources from Centos 4. But thanks 
anyway...

----- Original Message ----- 
From: "Oliver Falk" <oliver at linux-kernel.at>
To: "MailScanner discussion" <mailscanner at lists.mailscanner.info>
Sent: Wednesday, February 01, 2006 9:50 AM
Subject: Re: sendmail greet_pause feature


> On 02/01/2006 11:49 AM, Randal, Phil wrote:
>> You could always try grabbing the Centos 4.2 sendmail 8.13 source RPM
>> and rebuilding:
>>
>>   rpm --rebuild
>> http://anorien.csc.warwick.ac.uk/mirrors/centos/4.2/os/SRPMS/sendmail-8.
>> 13.1-2.src.rpm
>>
>> for example, and then installing (and reconfiguring as necessary).
>
> Go to http://rpms.linux-kernel.at/ and search for sendmail. You'll find 
> srpms that will work fine with CentOS and you'll also find rpms for CentOS 
> 3 and 4.1.
>
> Best,
>  Oliver
>
>> Cheers,
>>
>> Phil
>>
>> ----
>> Phil Randal
>> Network Engineer
>> Herefordshire Council
>> Hereford, UK
>>> -----Original Message-----
>>> From: mailscanner-bounces at lists.mailscanner.info 
>>> [mailto:mailscanner-bounces at lists.mailscanner.info] On Behalf Of Roger 
>>> Jochem
>>> Sent: 01 February 2006 10:26
>>> To: MailScanner discussion
>>> Subject: Re: sendmail greet_pause feature
>>>
>>> I'm using the rpm version of sendmail in my centos-3 box (sendmail 8.12) 
>>> and I would like to upgrade to sendmail 8.13 to use this feature, that 
>>> seems really great. Is there some problem I should be aware, or the 
>>> tar.gz version found at sendmail.org would work fine on my machine? 
>>> Anyone using 8.13 at
>>> centos-3 or some similar OS?
>>>
>>> Regards
>>>
>>> Roger Jochem
>>>
>>> ----- Original Message -----
>>> From: "Anders Andersson, IT" <anders.andersson at ltkalmar.se>
>>> To: "MailScanner discussion" <mailscanner at lists.mailscanner.info>
>>> Sent: Wednesday, February 01, 2006 8:01 AM
>>> Subject: RE: sendmail greet_pause feature
>>>
>>>
>>>>> -----Original Message-----
>>>>> From: mailscanner-bounces at lists.mailscanner.info
>>>>> [mailto:mailscanner-bounces at lists.mailscanner.info] On Behalf
>>>>> Of Jim Holland
>>>>> Sent: Wednesday, February 01, 2006 9:12 AM
>>>>> To: MailScanner mailing list
>>>>> Subject: OT: sendmail greet_pause feature
>>>>>
>>>>> Perhaps other sendmail users know all about this, but I have
>>>>> only looked at it for the first time.
>>>>>
>>>>> I run sendmail 8.13.1 and have decided to implement the
>>>>> greet_pause feature for the first time (after seeing that it
>>>>> is a default option in Debian installations).  This requires
>>>>> a specified delay after connection, which can be network
>>>>> specific, before a client system is allowed to send any SMTP
>>>>> commands.  Any client that breaks normal SMTP protocols by
>>>>> trying to force commands before receiving the go-ahead is
>>>>> immediately disconnected.  This seems to distinguish very
>>>>> successfully between genuine mailers and spammers/viruses
>>>>> that are not RFC-compliant.
>>>>>
>>>>> Using a 5 second delay I have found that the system has
>>>>> blocked over 3200 connections in the first 24 hours I used
>>>>> it.  The client systems were all typical of spammers, with
>>>>> adsl/ppp/dhcp/dialup/cable/cpe type hostnames or no PTR
>>>>> record at all.  I found only four systems in the blocked
>>>>> group that looked as if they were genuine.  On further
>>>>> investigation I found that earlier log records for some of
>>>>> those sites indicated behaviour typical of virus infections
>>>>> in any case.
>>>> I second that, thoguh I raised mine to 25 sec just for the
>>> fun of it. I
>>>> started low but raised it by 5 sec eeverytime and its been running
>>>> smooth. So far no one complained and the ones we have a great
>>>> mailexchange with been added to acces list
>>>>
>>>> /Anders
>>>>
>>>>> To implement the feature:
>>>>>
>>>>> Add the following to the sendmail.mc file:
>>>>>
>>>>> FEATURE(`greet_pause', `5000')dnl 5 seconds
>>>>>
>>>>> Rebuild sendmail and restart MailScanner:
>>>>>
>>>>> m4 < sendmail.mc > sendmail.cf
>>>>> service MailScanner restart
>>>>>
>>>>> Then specific entries for client hostname, domain, IP address
>>>>> or subnet can be put in the access file:
>>>>>
>>>>> GreetPause:my.domain    0
>>>>> GreetPause:example.com  5000
>>>>> GreetPause:10.1.2       2000
>>>>> GreetPause:127.0.0.1    0
>>>>>
>>>>> Definitely worth a look I would say, as it blocks large
>>>>> numbers of spammers before they are allowed to send any data,
>>>>> with very low risk of blocking genuine systems.  It even
>>>>> seems to allow genuine mail from infected systems to be
>>>>> accepted while blocking viruses from those same systems
>>>>> before the DATA phase - as many viruses seem to behave rather
>>>>> impolitely :-)
>>>>>
>>>>> Regards
>>>>>
>>>>> Jim Holland
>>>>> System Administrator
>>>>> MANGO - Zimbabwe's non-profit e-mail service
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