查看當天登陸未成功的IP

一條命令把這些IP全部封掉：

for i in `grep "$(date +"%b %d")" /var/log/secure | grep "Failed password" | awk "{print $(NF-3)}" | sort | uniq -c | sort -nr| awk "{print $2}"` ;do iptables -A INPUT -s $i -j DROP; done

效果：