Source-routed packets allow the source of the packet to suggest that routers forward the packet along a different path than configured on the router, which can be used to bypass network security measures. This requirement applies only to the forwarding of source-routed traffic, such as when IPv6 forwarding is enabled and the system is functioning as a router.
Check
If IPv6 is not enabled, the key will not exist, and this is Not Applicable.
Verify the system does not accept IPv6 source-routed packets.
If "net.ipv6.conf.all.accept_source_route" is not configured in the /etc/sysctl.conf file or in the /etc/sysctl.d/ directory, is commented out or does not have a value of "0", this is a finding.
Check that the operating system implements the accept source route variable with the following command:
# /sbin/sysctl -a | grep net.ipv6.conf.all.accept_source_route net.ipv6.conf.all.accept_source_route = 0
If the returned lines do not have a value of "0", this is a finding.
Fix
Set the system to the required kernel parameter, if IPv6 is enabled, by adding the following line to "/etc/sysctl.conf" or a configuration file in the /etc/sysctl.d/ directory (or modify the line to have the required value):
net.ipv6.conf.all.accept_source_route = 0
Issue the following command to make the changes take effect: