linux vps 自动拒绝弱口令ssh扫描

vi block.sh

#! /bin/bash
cat /var/log/secure | awk ‘/Failed/{print $(NF-3)}‘| sort | uniq -c|awk ‘{print $2"="$1;}‘ > /root/black.txt
DEFINE="5"
for i in `cat /root/black.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

vi /etc/crontab

*/10 * * * * root /bin/sh /root/block.sh >/dev/null 2>&1