1.添加epel的YUM源

1.  cd /etc/yum.repos.d/

2.  rpm --import http://mirrors.ustc.edu.cn/fedora/epel/RPM-GPG-KEY-EPEL-6

3.   

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

5.  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