Simply block DDOS attack

ddosdeny.sh

#!/bin/bash
##
## Simply block DDOS attack
##

ARGV1=$1
if [ $ARGV1 ]; then
  DEFINE=$ARGV1
else
  DEFINE="100"
fi

netstat -an | grep :80 | grep -v 127.0.0.1 | awk '{ print $5 }' | sort | awk -F: '{ print $1, $4 }' | uniq -c | awk ' $1 > 100 { print $1, $2 }' > /tmp/blackname.txt

for i in `awk '{ print $2 }' /tmp/blackname.txt`
do
     COUNT=`grep $i /tmp/blackname.txt | awk '{ print $1 }'`
     ZERO="0"
     if [ $COUNT -gt $DEFINE ]; then
         grep -F $i /opt/whitename.txt > /dev/null
         if [ $? -gt $ZERO ]; then
             echo "Drop $i"
             iptables -I INPUT -p tcp -s $i -j DROP
         fi
     fi
done