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V-230039

CAT III (Low)

The Cisco router must be configured to advertise a hop limit of at least 32 in Router Advertisement messages for IPv6 stateless auto-configuration deployments.

Rule ID

SV-230039r647454_rule

STIG

Cisco IOS XE Router RTR Security Technical Implementation Guide

Version

V3R5

CCIs

CCI-000366

Discussion

The Neighbor Discovery protocol allows a hop limit value to be advertised by routers in a Router Advertisement message being used by hosts instead of the standardized default value. If a very small value was configured and advertised to hosts on the LAN segment, communications would fail due to the hop limit reaching zero before the packets sent by a host reached its destination.

Check Content

Review the router configuration to determine if the hop limit has been configured for Router Advertisement messages as shown in the example.

ipv6 hop-limit 128

If it has been configured and has not been set to at least 32, it is a finding.

Fix Text

Configure the router to advertise a hop limit of at least 32 in Router Advertisement messages.

R1(config)#ipv6 hop-limit 128