Just follow this:http://www.haiyun.me/archives/centos-freeradius-daloradius-ros.html, and I will list something different in CentOS7
#1:CentOS7 replaces mysql with mariaDB, try this
yum install mariadb-server mariadb
or if you insist on installing mysql, follow this:http://www.server180.com/2014/09/how-to-install-mysql-on-centos-7-step.html
#2:As mariaDB is a drop-in replacement for MySQL, we use follow commands:
mysqladmin
mysql
#3:In CentOS7, try these commands to install freeradius
//To see what is able to install yum list|grep freeradius //I use these commands to intall it yum install freeradius freeradius-mysql freeradius-utils
#4:Try these to start service:
service httpd start
service mysql start
service radiusd start