there is a other way to secure the server easy , but its harder to let your server works
use the mysql socked methode and get only acces from localhost
then even when they get a remote conection to your localhost then they cant conect becosue the socked that is needed ( its for linux :P )
i dont know mutch about it but i know that even then wildcards refuse to work (got trouble whit it whit my other host )
for the rest , you can get acces from remote to localhost , first you make a conection to your server ip and from there you make a link to the db (kind of hacking isnt it ^^ )
so its not 100% safe , how safer you want to make it how harder it is to get your server running , but when it runs then it is safe ^^
Greets From The crasher