BFD is a shell script which parses security logs and detects authentication failures. It is a brute force implementation without much complexity, and it works in conjunction with a APF (Advanced Policy-based Firewall).

## Get the latest source and untar.
# cd /usr/src/utils
# wget http://rfxnetworks.com/downloads/bfd-current.tar.gz
# tar xfz bfd-current.tar.gz
# cd bfd-*
# ./install.sh

Read the README file, and edit the configuration file located in /usr/local/bfd/conf.bfd.
Find ALERT=”0″ and replace it with ALERT=”1″
Find EMAIL_USR=”root” and replace it with EMAIL_USR=”username@yourdomain.com”

Edit /usr/local/bfd/ignore.hosts file, and add your own trusted IPs. BFD uses APF and hence it orverrides allow_hosts.rules, so it is important that you add trusted IP addresses to prevent yourself from being locked out.

## Start the program.
# /usr/local/sbin/bfd -s

What is APF (Advanced Policy Firewall)? APF Firewall
APF is a policy based iptables firewall system designed for ease of use and configuration. It employs a subset of features to satisfy the veteran Linux user and the novice alike. Packaged in tar.gz format and RPM formats, make APF ideal for deployment in many server environments based on Linux. APF is developed and maintained by R-fx Networks: http://www.rfxnetworks.com/apf.php

This guide will show you how to install and configure APF firewall, one of the better known Linux firewalls available.

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