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Configuring ND attack defense
Overview
Neighbor Discovery (ND) attack defense is able to identify forged ND messages to prevent ND
attacks.
The IPv6 ND protocol does not provide any security mechanisms and is vulnerable to network
attacks. An attacker can send the following forged ICMPv6 messages to perform ND attacks:
•
Forged NS/NA/RS messages with an IPv6 address of a victim host. The gateway and other
hosts update the ND entry for the victim with incorrect address information. As a result, all
packets intended for the victim are sent to the attacking host.
•
Forged RA messages with the IPv6 address of a victim gateway. As a result, all hosts attached
to the victim gateway maintain incorrect IPv6 configuration parameters and ND entries.
For information about the IPv6 ND protocol, see
Layer 3
–
IP Services Configuration Guide
.
Table 22 ND attack defense features at a glance
ND attack defense
feature
Configured on
To block
Source MAC consistency
check
Gateways
ND messages in which the Ethernet frame header
and the source link-layer address option of the ND
message contain different source MAC addresses.
ND attack detection
Access devices
ND messages in which the mapping between the
source IPv6 address and the source MAC address is
invalid.
RA guard
Layer 2 access
devices
RA messages incompliant with the RA guard policy
or identified to be sent from hosts.
Configuration restrictions and guidelines
Do not configure ND attack detection or RA guard on the following interfaces or VLANs:
•
Layer 2 Ethernet or aggregate interfaces where QinQ or VLAN mapping is configured.
•
VLANs to which these interfaces belong.
For more information about QinQ or VLAN mapping, see
Layer 2
–
LAN Switching Configuration
guide
.
Configuring source MAC consistency check for
ND messages
The source MAC consistency check feature is typically configured on gateways to prevent ND
attacks.
This feature checks the source MAC address and the source link-layer address for consistency for
each arriving ND message.
•
If the source MAC address and the source link-layer address are not the same, the device
drops the packet.
•
If the addresses are the same, the device continues learning ND entries.
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