grep "Failed password for root" /var/log/auth.log | awk '{print $11}' | sort | uniq -c | sort -nr | more
centos查看尝试登录服务器的ip，一般用来查看攻击ip来源：
cat /var/log/secure | awk '/Failed/{print $(NF-3)}'| sort| uniq -c| awk '{print $2"="$1;}'
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