NET-IPV6-010 - Inbound ICMPv6 messages are not blocked - 'deny icmp any any fragments log'


The network element can permit inbound ICMPv6 messages Packet-too-big (type 2), Time Exceeded (type 3), Parameter Problem (type 4), Echo Reply (type 129), and Neighbor Discovery (type 135-136). Remaining ICMPv6 messages must be blocked inbound.

Scanning will usually be the major stage of an information gathering process a malicious computer attacker will launch against a targeted network. With this stage the malicious computer attacker will try to determine what the characteristics of the targeted network are. Techniques, such as host detection, service detection, network topology mapping, and operating system fingerprinting are often used. The data collected will be used to identify those Hosts (if any) that are running a network service, which may have a known vulnerability. This vulnerability may allow the malicious computer attacker to execute a remote exploit in order to gain unauthorized access to those systems. This unauthorized access may become the focal point to the whole targeted network.

NOTE: Change 'IPV6_INGRESS_ACL' to the access control list for IPv6 inbound connection filtering.


The network element must be configured to include controls to block inbound exploitable ICMP traffic message types.

Supportive Information

The following resource is also helpful.

This security hardening control applies to the following category of controls within NIST 800-53: System and Communications Protection.This control applies to the following type of system Cisco.