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• Neighbor reachability detection

• Duplicate address detection (DAD)

• Router/prefix discovery and address autoconfiguration

• Redirection

Five types of the ICMPv6 messages are listed below:

ICMPv6 Message Function

Neighbor Solicitation (NS)

• Acquires the neighbor’s link-layer address.

• Verifies whether a neighbor is reachable.

• Detects duplicate address.

Neighbor Advertisement

(NA)

• Responses to an NS message.

• Notifies the neighbor nodes of link layer changes

Router Solicitation (RS)

•

Requests for an address prefix and other

configuration parameters for autoconfiguration.

Router Advertisement (RA)

• Responses to an RS message.

•

Advertises information such as the prefix

information options and flag bits.

Redirect (RR)

• Informs the source host of another next hop to a

particular destination when certain conditions

are met.

 ND Attack

Because of the absence of security mechanism, ND protocol is easy to be exploited by

attackers. Attackers can exploit the ND protocols as follows:

• The attackers send forged NS/NA/RS packets with the IPv6 address of a victim host. The

gateway or the other hosts who have received these NS/NA/RS packets will update their ND

entry with the wrong address information. AS a result, all packets intended for the victim will

be sent to the attacking host rather than the victim host.

• The attackers send forged RA packets with the IPv6 address of a victim gateway. All the

hosts attached to the victim gateway may receive incorrect IPv6 configuration parameters

and maintain false ND entries.

A forged ND packet has the following two features:

• The source MAC address in the Ethernet frame header is inconsistent with that carried in

the source link layer address option of the ND packet.

• The mapping between the source IPv6 address and the source MAC address in the Ethernet

frame header is invalid.

 ND Detection Process

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