How iptables directs to localhost in this series of iptable rules Post: 302570585

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Top Forums UNIX for Advanced & Expert Users How iptables directs to localhost in this series of iptable rules Post 302570585 by Corona688 on Thursday 3rd of November 2011 04:57:23 PM

11-03-2011

Registered User

Quote:

Originally Posted by Narnie

#4 is dropping broadcast packets, but I'm not exactly sure where those would come from. #4 and #5 I have found on other sites that on networks with Windows systems on them, there will be a lot of broadcast and multicast packets on them that will hog the logs, so it just drops them. Does this make since? If not, other explainations are welcome. Not sure what Windows is doing here, but it seems to be in some of the "best practices" info on firewall building.

Older versions of MS Messenger spam broadcast messages continuously.

I don't see why the firewall needs to care about this either.

Quote:

#6 I understand the difference, but wonder why sometimes things are just dropped (and therefore silent) and if everything makes it through the rules to this point, it might be chosen to use are REJECT and thus send back a TCP RST packet alerting them that they got a "live" system. Just curious on this one.

That's often why things are DROPped instead of REJECTed, yes.

Some firewalls even have a 'tarpit' sort of thing to dump known-hostile connections into. Tarpitted hosts get just enough response from the server to think they've connected, but they haven't. Tarpitted connections still take the usual ten minutes timeout before dying. I think it's a strategy against DDOS.

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LEARN ABOUT DEBIAN

arno-iptables-firewall

ARNO-IPTABLES-FIREWALL(8)												 ARNO-IPTABLES-FIREWALL(8)

NAME

       arno-iptables-firewall - Single- & multi-homed firewall script with DSL/ADSL support.

SYNOPSIS

       /etc/init.d/arno-iptables-firewall [start|stop|status|force-reload|restart]

DESCRIPTION

       arno-iptables-firewall  is  an  iptables configuration script with support for both IPv4 & IPv6.  While it is extremely easy to use one can
       nevertheless use it in quite complicated environments.

       All available options are explained in the extensively documented configuration file.

       The external interface of the system needs to be set up properly in the firewalls configuration file (EXT_IF).  The default behavior of the
       firewall is to deny all incoming connections.

       For  additional	requirements not covered by the configuration file custom iptables rules can be placed in /etc/arno-iptables-firewall/cus-
       tom-rules.  This file is automatically parsed by the service script.

       See the README file (eg. in /usr/(local/)share/doc/arno-iptables-firewall) for an example how to manage logging of firewall events  through
       syslogd.

       The arno-fwfilter script can be used to make the firewall logs more readable for humans (see manpage).

       Several plugins for the firewall script are available online. Plugins can be downloaded from http://rocky.eld.leidenuniv.nl/ Please see the
       README file for more information.

FILES

       /etc/init.d/arno-iptables-firewall	       system service script
       /etc/arno-iptables-firewall/firewall.conf       firewall configuration
       /etc/arno-iptables-firewall/conf.d/	       firewall configuration directory
       /etc/arno-iptables-firewall/custom-rules        custom iptables rules
       /etc/arno-iptables-firewall/blocked-hosts       host blacklist
       /etc/arno-iptables-firewall/mac-addresses       mac filter list

       Please note, that the last two files do exist in the initial configuration and their use is disabled  in  /etc/arno-iptables-firewall/fire-
       wall.conf

SEE ALSO

       iptables(8), arno-fwfilter(1), syslog.conf(5)

       The http://rocky.eld.leidenuniv.nl/ web site.

AUTHOR

       arno-iptables-firewall was written by Arno van Amersfoort <arnova@rocky.eld.leidenuniv.nl>.

       This manual page was written by Michael Hanke <michael.hanke@gmail.com>, for the Debian project (but may be used by others).

Michael Hanke							  March 14, 2012					 ARNO-IPTABLES-FIREWALL(8)