1.添加epel的YUM源
cd /etc/yum.repos.d/
rpm --import http://mirrors.ustc.edu.cn/fedora/epel/RPM-GPG-KEY-EPEL-6

wget https://lug.ustc.edu.cn/wiki/_export/code/mirrors/help/epel?codeblock=0 && mv epel?codeblock=0 epel.repo
wget https://lug.ustc.edu.cn/wiki/_export/code/mirrors/help/epel?codeblock=1 && mv epel?codeblock=1 epel-testing.repo

2、安装： yum install fail2ban