Fail2Ban

Fail2Ban is a limited intrusion detection/prevention system. It works by scanning log files and then banning IPs based on the entries in those logs. Note that Digium is moving away from writing security information to log files, and is now using AMI events. Consider fail2ban a short-term solution only.

You can get Fail2Ban, as well as more documentation, at www.fail2ban.org. At the time this is being written, the current release is 0.8.4.

Fail2Ban With Asterisk

The following describes how to setup Fail2Ban to protect an Asterisk PBX from SIP brute force attempts and scans utilizing the iptables firewall.

SECURITY NOTE: fail2ban is rather limited in its ability to detect attacks against asterisk.
More info http://forums.asterisk.org/viewtopic.php?p=159984
Consider a more comprehensive product like the free edition of SecAst www.generationd.com

Easy Install Script for Fail2ban version 0.8.4 / Red Hat

This script was written by Cédric Brohée in order to simplify and accelerate the integration of the solution in a basic Asterisk configuration on Red Hat.
Do not hesitate to read the bash script and make changes to match your own configuration.

Before running it, you will have to do chmod 755.

Download script with new dedicated sources :

Installing

Log into the system and su - root, or sudo -i to get a root shell on Ubuntu.

CentOS/Red Hat (this method may install an older version of fail2ban):

Install rpmforge or optionally fetch the fail2ban rpm directly from rpmforge. ...