4.4.1.2 Disable IPv6 Redirect Acceptance - net.ipv6.conf.default.accept_redirect = 0

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

See Also

https://workbench.cisecurity.org/files/3096

Item Details

Category: CONFIGURATION MANAGEMENT

References: 800-53|CM-7b., CSCv7|9.2

Plugin: Unix

Control ID: bc7c73c2f484649bf648a8100aa609b384a2e385453dc933dcacd13adb4bad9a