Command Center

(D)DoS Deflate is a lightweight bash shell script designed to assist in the process of blocking a denial of service attack. It utilizes the command below to create a list of IP addresses connected to the server, along with their total number of connections. It is one of the simplest and easiest to install solutions at the software level.

netstat -ntu | awk '{print $5}' | cut -d: -f1 | sort | uniq -c | sort -n

IP addresses with over a pre-configured number of connections are automatically blocked in the server's firewall, which can be direct iptables or Advanced Policy Firewall (APF). (We highly recommend that you use APF on your server in general, but deflate will work without it.)
Notable Features

It is possible to whitelist IP addresses, via /usr/local/ddos/ignore.ip.list.
Simple configuration file: /usr/local/ddos/ddos.conf
IP addresses are automatically unblocked after a preconfigured time limit (default: 600 seconds)
The script can run at a chosen frequency via the configuration file (default: 1 minute)
You can receive email alerts when IP addresses are blocked.

Installation

wget http://www.inetbase.com/scripts/ddos/install.sh
chmod 0700 install.sh
./install.sh

#!/bin/sh
if [ -d '/usr/local/ddos' ]; then
 echo; echo; echo "Please un-install the previous version first"
 exit 0
else
 mkdir /usr/local/ddos
fi
clear
echo; echo 'Installing DOS-Deflate 0.6'; echo
echo; echo -n 'Downloading source files...'
wget -q -O /usr/local/ddos/ddos.conf http://www.inetbase.com/scripts/ddos/ddos.conf
echo -n '.'
wget -q -O /usr/local/ddos/LICENSE http://www.inetbase.com/scripts/ddos/LICENSE
echo -n '.'
wget -q -O /usr/local/ddos/ignore.ip.list http://www.inetbase.com/scripts/ddos/ignore.ip.list
echo -n '.'
wget -q -O /usr/local/ddos/ddos.sh http://www.inetbase.com/scripts/ddos/ddos.sh
chmod 0755 /usr/local/ddos/ddos.sh
cp -s /usr/local/ddos/ddos.sh /usr/local/sbin/ddos
echo '...done'

echo; echo -n 'Creating cron to run script every minute.....(Default setting)'
/usr/local/ddos/ddos.sh --cron > /dev/null 2>&1
echo '.....done'
echo; echo 'Installation has completed.'
echo 'Config file is at /usr/local/ddos/ddos.conf'
echo 'Please send in your comments and/or suggestions to zaf@vsnl.com'
echo
cat /usr/local/ddos/LICENSE | less

Uninstallation

wget http://www.inetbase.com/scripts/ddos/uninstall.ddos
chmod 0700 uninstall.ddos
./uninstall.ddos


REFERENCES
http://deflate.medialayer.com/