Iptable Rules to secure microk8s


how do i secure my microk8s instance instance to only open ports that i want?
for example, i want to deny all but open a specific port for a service.
I tried the following for opening port 32001 only without success:

iptables -A INPUT -j drop
iptables -A INPUT --protocol tcp --dport 32001 -j ACCEPT

There are still all other ports open.
I also searched in the documentation of micrk8s, but couldnt find anything.

thanks for help :wink: