1. edit /etc/mysql/my.cnf
2. locate line that read as [mysqld]
3. make sure line skip-networking is commented and add line bind-address=YOUR-SERVER-IP
4. restart mysql service to take change in effect /etc/init.d/mysql restart
5. grant privileges in MySQL, GRANT ALL ON *.* TO 'username'@'%' IDENTIFIED BY 'PASSWORD';
6. update iptables, iptables -A INPUT -i eth0 -p tcp --destination-port 3306 -j ACCEPT