First we need to add the repository:

rpm -Uvh http://dl.fedoraproject.org/pub/epel/6/x86_64/epel-release-6-8.noarch.rpm

Then we can install fail2ban with

yum install fail2ban

The default configuration file is jail.conf however we should avoid making changes to this and instead make changes to jail.local. Use the following command to make jail.local

cp /etc/fail2ban/jail.conf /etc/fail2ban/jail.local