The router must be configured to drop all fragmented Internet Control Message Protocol (ICMP) packets destined to itself.

Fragmented ICMP packets can be generated by hackers for DoS attacks such as Ping O' Death and Teardrop. It is imperative that all fragmented ICMP packets are dropped.

Review the access control list (ACL) or filter for the router receive path.

Verify that it will drop all fragmented ICMP packets destined to itself.

If the router is not configured with a receive-path filter to drop all fragmented ICMP packets, this is a finding.

Note: If the platform does not support the receive path filter, verify that all Layer 3 interfaces have an ingress ACL to control what packets are allowed to be destined to the router for processing.

Ensure all routers have their receive path filter configured to drop all fragmented ICMP packets.