Firewall Rule to prevent DNS rebinding attack

[Valkeram]

I've just watched a very interesting Youtube video demonstrating Router attacks by DNS rebinding. It seems that the BiPAK 7800N is vulnerable and it is suggested that a firewall rule preventing any access to the routers public IP address from any local address be created.
Has anyone created such a rule? I am not confident that I understand the creation of firewall rules enough to leap in unaided.
Any help please?