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Groups > comp.os.linux.networking > #2014

Re: Dropping connection attempts to port 25

From David Hough <noone$$@llondel.org>
Organization the bus stop
Date 2013-03-12 07:29 +0000
Subject Re: Dropping connection attempts to port 25
Newsgroups comp.os.linux.networking
References <khkqrs$msg$1@news.albasani.net>
Message-ID <i4231a-1m6.ln1@llondel.org> (permalink)

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Clark Smith wrote:

> Somebody keeps trying to connect to my sendmail server, without
> success, but filling my logs in the process. Since, according to the
> sendmail logs, the connection seems to be coming from a specific IP
> address <ip>, I added the following IPTables rules:
> 
> iptables -A INPUT -s <ip> -j DROP
> iptables -A OUTPUT -d <ip> -j DROP
> 
> However, I can still see further connection attempts in the sendmail logs.
> 
> Any ideas on how to get IPTables to drop such attempts before
> they get to sendmail?

Is this a border firewall that is forwarding stuff to other machines on the 
inside, or is it the same machine that's running sendmail? If it's a 
forwarding firewall then you need to be adding the rules to the FORWARD 
table, not the INPUT table.

Dave

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Thread

Dropping connection attempts to port 25 Clark Smith <noaddress@nowhere.net> - 2013-03-11 14:48 +0000
  Re: Dropping connection attempts to port 25 Richard Kettlewell <rjk@greenend.org.uk> - 2013-03-11 14:58 +0000
    Re: Dropping connection attempts to port 25 Clark Smith <noaddress@nowhere.net> - 2013-03-11 15:12 +0000
      Re: Dropping connection attempts to port 25 Richard Kettlewell <rjk@greenend.org.uk> - 2013-03-11 16:24 +0000
      Re: Dropping connection attempts to port 25 Octothorpe <Octothorpe@invalid.com> - 2013-03-11 16:38 -0400
        Re: Dropping connection attempts to port 25 Richard Kettlewell <rjk@greenend.org.uk> - 2013-03-12 10:16 +0000
  Re: Dropping connection attempts to port 25 Dale Dellutri <ddelQQQlutr@panQQQix.com> - 2013-03-11 14:58 +0000
    Re: Dropping connection attempts to port 25 Clark Smith <noaddress@nowhere.net> - 2013-03-11 15:15 +0000
  Re: Dropping connection attempts to port 25 David Hough <noone$$@llondel.org> - 2013-03-12 07:29 +0000
  Re: Dropping connection attempts to port 25 Joe Beanfish <joebeanfish@nospam.duh> - 2013-03-12 13:21 +0000

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