3.3.2 Ensure IPv6 redirects are not accepted - /etc/sysctl ipv6 default accept

Information

This setting prevents the system from accepting ICMP redirects. ICMP redirects tell the system about alternate routes for sending traffic.

Rationale:

It is recommended that systems not accept ICMP redirects 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_redirects = 0
net.ipv6.conf.default.accept_redirects = 0

Run the following commands to set the active kernel parameters:

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

See Also

https://workbench.cisecurity.org/files/3738

Item Details

Category: SYSTEM AND COMMUNICATIONS PROTECTION

References: 800-53|SC-7(12)

Plugin: Unix

Control ID: dc5814b2dc5cfebb7654d0afc1df44e6b0518884ad0c49af0f9b5f81222d6a5f