What is a successful method for protecting a router from potential smurf attacks?

Placing a router in broadcast mode would amplify the attack by increasing the number of hosts that respond to broadcast pings, worsening the impact.

Port forwarding redirects specific TCP/UDP traffic to internal hosts and has no effect on ICMP broadcast amplification used in smurf attacks.

Installing the router outside the firewall increases its exposure to attack rather than protecting it from smurf-style broadcast flooding.

A smurf attack works by sending spoofed ICMP echo requests to a network broadcast address, causing all hosts to reply to the victim. Disabling the router from accepting or forwarding directed broadcast ping messages eliminates the amplification mechanism entirely, preventing the attack from succeeding.