Level 1 - Server Level 1 - Workstation
This setting prevents the system from accepting ICMP redirects. ICMP redirects tell the system about alternate routes for sending traffic.
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.
Run the following command and verify output matches:
# sysctl net.ipv6.conf.all.accept_redirects net.ipv6.conf.all.accept_redirect = 0 # sysctl net.ipv6.conf.default.accept_redirects net.ipv6.conf.default.accept_redirect = 0
Set the following parameter in the /etc/sysctl.conf 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