Re: how to block connections at TCP level?

man, 09.02.2004 kl. 14.28 skrev Igor Lidin:

> Is there any possibility to block incoming SMTP connections to port 25 controlled by postfix at TCP level (e.g. refuse connection or at least disconnect immediately) using filtering rules already supported by postfix - cidr maps, tcp maps, dnsbl checks and so on?

Postfix can not refuse at TCP level (OSI level 3). Your firewall can. An
alternative might be Wietse's tcp wrappers.

> It is needed because of huge traffic amount that eated by useless spam connections (e.g. from *.ipt.aol.com) that are filtered anyway at "client" stage.
>
> It may be implemented as something like smtpd_tcp_restrictions configuration variable.

Don't see how. I block via Postfix using smtpd_recipient_restrictions.
That works fine for me (at the moment I'm blocking up to 40% of all MAIL
FROM:/RCPT TO: offerings), but YMMV. BTW, this has risen from around
10-15% within the last week.

--Tonni

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