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 net.ipv6.conf.all.accept_redirects and net.ipv6.conf.default.accept_redirects parameters to 0 in /etc/sysctl.conf:
net.ipv6.conf.all.accept_redirects=0
net.ipv6.conf.default.accept_redirects=0
Run the following commands to set the active kernel parameters:
# /sbin/sysctl -w net.ipv6.conf.all.accept_redirects=0
# /sbin/sysctl -w net.ipv6.conf.default.accept_redirects=0
# /sbin/sysctl -w net.ipv6.route.flush=1