3.3.9 Ensure IPv6 router advertisements are not accepted

Information

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

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

IF IPv6 is enabled:

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/3682