通过shell脚本来防止暴力破解ssh

#!/bin//bash
cat /var/log/secure | awk 'Failed/{print $(NF-3)}' | sort | uniq -c | awk '{print $2"="$1;}' > /root/satools/blacklists.info

BAN="20"
for i in `cat /root/satools/blacklists.info`
        do
                IP=`echo $i |awk -F= '{print $1}'`
                NUM=`echo $i |awk -F= '{print $2}'`

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

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