Denyhosts shell script

#!/bin/sh
#Denyhosts shell script

cat /var/log/secure | awk '/Failed/{print $(NF-3)}' | sort | uniq -c | awk '{print $2"="$1;}' > /root/blacklist.txt

DEFINE="5"

for i in `cat /root/blacklist.txt`
do
IP=`echo $i | awk -F= '{print $1}'`
NUM=`echo $i | awk -F= '{print $2}'`

if [ $NUM -gt $DEFINE ];
then grep $IP /etc/hosts.deny > /dev/null

if [ $? -gt 0 ];
then echo "sshd:$IP" >> /etc/hosts.deny
fi
fi
done

* */1 * * * sh /root/shell/deny-ssh.sh