NO communication between Lan1 and Lan2

Hi every one
Please i have two local Lans with both connecting to the internet through the same Wan. But i dont want Lan1 and Lan2 to be able to ping each other. Please how do i achieve this
Thanks

Festus

I have done this with IP firewall.

Set up an input chain for each network. (Two total chains.)

Source address one network. Destination address the other network.

The action is to reject with icmp network unreachable.

Tom

Thanks Tom, it worked, you realy saved my day.