Port 3306 mysql probe

I found a large number of failed connection attempts to port 3306 of my FC7 server. This port is for external hosts connect to mysqld. Since I do not open mysqld for connection by other hosts, leaving this port opens is a bad vulnerability otherwise bad guys can proble mysqld root password.

Closing port 3306 can be done by amending the mysql config file. This is too complicated. I just use iptables to get this job easily done.