3.2.9 Ensure IPv6 router advertisements are not accepted - sysctl net.ipv6.conf.all.accept_ra

Information

This setting disables the system's ability to accept IPv6 router advertisements.

Rationale:

It is recommended that systems do not accept router advertisements as they could be
tricked into routing traffic to compromised machines. Setting hard routes within the
system (usually a single default route to a trusted router) protects the system from bad
routes.

Solution

Set the following parameters in /etc/sysctl.conf or a /etc/sysctl.d/* file:

net.ipv6.conf.all.accept_ra = 0
net.ipv6.conf.default.accept_ra = 0

Run the following commands to set the active kernel parameters:

# sysctl -w net.ipv6.conf.all.accept_ra=0
# sysctl -w net.ipv6.conf.default.accept_ra=0
# sysctl -w net.ipv6.route.flush=1

See Also

https://workbench.cisecurity.org/files/2420