not work: iptables -I INPUT 5 -m state --state NEW -m tcp -p tcp --dport 3306 -j DROP
 

This IP tables command is still letting connections through other than myip:
iptables -I INPUT 1 -m state --state NEW -m tcp -p tcp -s myip/32 --dport 3306 -j ACCEPT
iptables -I INPUT 5 -m state --state NEW -m tcp -p tcp --dport 3306 -j DROP

Why isnt that working?

hi,

what policy you have for the INPUT? DROP or ACCEPT?
and, pls set your blocked interface and turn on logging - easier to troubleshoot.
in your rule - even your loopback address cant connect to your sql.

HTH.