blok data traffic between public and privat network

RouterOS Beginner Basics
1

Eth1 = wan nat activated Eth2 = public ip-range 192.168.1.0/24 Eth3 = privat ip-range 192.168.2.0/24
How do I block data traffic between public and privat network
How do I block the users who use the public network of the private network

2 
/ip firewall filter
add action=drop chain=forward in-interface=ether2 out-interface=ether3
add action=drop chain=forward in-interface=ether3 out-interface=ether2
3

tnx for you anser, but i can still ping the interfaces
why?

4

That is because you are pinging the router itself if you are pinging an interface. Therefore the traffics destination is the router and doesn’t need to be forwarded, and that is on the input chain, not the forward.