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BFD (Brute Force Detection) 1.5-2 [bfdr-fx.org]
 Copyright (C) 1999-2008, R-fx Networks <[email protected]>
 Copyright (C) 2008, Ryan MacDonald <[email protected]>

    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation; either version 2 of the License, or
    (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program; if not, write to the Free Software
    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

1) Introduction:
BFD is a modular shell script for parsing application logs and checking for
authentication failures. It does this using a rules system where application
specific options are stored including regular expressions for each unique auth
format. The regular expressions are parsed against logs using the 'sed' tool
(stream editor) which allows for vastly superior performance as opposed to
perl based regular expressions or using other tools such as grep/egrep.

Although some will argue that perl based stream processing is far more flexible
than unix tools, I argue that perl is a bloated framework to depend upon and unix
tools such as sed are universal across *nix. Further, perl is only more flexible
with regular expression based stream 'editing', such as in place editing etc..,
if you are only processing a data stream (as bfd does) then sed wins hands down.

In addition to the benefits of parsing logs in a single stream, BFD also uses a
log tracking system so logs are only parsed from the point which they were last
read. This greatly assists in extending the performance of BFD even further as
we are not constantly reading the same log data. The log tracking system is
compatible with syslog/logrotate style log rotations which allows it to detect
when rotations have happened and grab log tails from both the new log file and
the rotated log file.

You can also leverage BFD to block attackers using any number of tools such as
APF, Shorewall, raw iptables, ip route or execute any custom command. There is 
also a fully customizable e-mail alerting system with an e-mail template that
is well suited for every day use or you can open it up and modify it.

The attacker tracking in BFD is handled using simple flat text files that are
size-controlled to prevent space constraints over time, ideal for disk less
devices. There is also an attack pool where trending data is stored on all hosts
hat have been blocked including which rule the block was triggered by.

In the execution process, there is simply a cron job that executes BFD once
every 3 minutes by default. An embedded lock file system makes sure that no
two instances ever run at the same time, preventing messy and potentially load
heavy results. The cronjob can be run more frequently for those that desire it
and doing so will not cause any performance issues (no less than once a minute).

2) Installation:
The included install.sh script does as it says, it will install bfd to the
'/usr/local/bfd' path and place a 3-minute cronjob in '/etc/cron.d/bfd'. The
setup script will also execute an included 'importconf' script if you have a
previous version of bfd installed, which will import your previous settings.

Although it is supported to customize the default installation layout of BFD,
it is not something I recommend or have done much testing with so do so as
you see fit :-)

3) Configuration:
The configuration file for BFD is located at '/usr/local/bfd/conf.bfd', it is
very straight forward and the comments explain themself as to what each option
is for. The most important option is the TRIG="" value in conf.bfd as this
controls how many failed logins before an address is blocked. You should also
make sure to configure an email address and to turn on email alerting to stay
informed on any bans that are placed.

An ignore file is present at '/usr/loca/bfd/ignore.hosts', this is a line
spaced file to place IP Addr's into that you would like to be ignored for
authentication failures. An internal function will attempt to fetch all local
IP's bound on the installed system and ignore any events appearing to source
from those local addresses (but still send an alert).

The application rule files are located under '/usr/local/bfd/rules/' and
they use a simple check feature to auto-enable them self based on the existence
of specific application files. As an example, if the file '/usr/sbin/exim' is
found to exist then the exim rule will be enabled for processing.

You may wish to set unique trigger values for each application and this can be
done by opening the rule in question (i.e: /usr/local/bfd/rules/exim) and set
the TRIG="" value to whatever amount of failed authentications you would like a
ban to be issued at.

If you would like to have BFD place bans via a facility other than the default
configured APF ban command, you can do so by editing the BAN_COMMAND option in
conf.bfd. As an example you can use a generic system route reject to drop hosts
like so:

BAN_COMMAND="route add -host $ATTACK_HOST reject"

4) License:
BFD is developed and supported on a volunteer basis by Ryan MacDonald
[[email protected]]

BFD (Brute Force Detection) is distributed under the GNU General Public
License (GPL) without restrictions on usage or redistribution. The BFD
copyright statement, and GNU GPL, "COPYING.GPL" are included in the top-level
directory of the distribution. Credit must be given for derivative works as
required under GNU GPL.

5) Support:
If you require any assistance with BFD you may refer to the R-fx Networks
community forums located at http://forums.rfxnetworks.com. You may also send
an e-mail to [email protected].

The offical home page for BFD is located at:
http://www.rfxnetworks.com/bfd.php

All bugs or feature requests should be sent to [email protected] and please be sure
to include as much information as possible or conceptual ideas of how you think
a new feature should work.