How to block mysql port 3306 for everybody, but allow it for a specific IP? This is what I currently do:
iptables -I INPUT 1 -p tcp --dport 3306 -j ACCEPT
You need multiple rules to do that. In most cases, what will happen with a connection depends on the first rule, which it matches. So, first we accept our friends connection, second, we drop anybody other. Voila!
iptables -I INPUT 1 -p tcp -s 18.104.22.168 --dport 3306 -j ACCEPT iptables -I INPUT 2 -p tcp --dport 3306 -j DROP