Source-routed packets allow the source of the packet to suggest 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-routerd traffic, such as when IPv4 forwarding is enabled and the system is functioning as a router.
Accepting source-routed packets in the IPv4 protocol has few legitimate uses. It must be disabled unless it is absolutely required.
Check
Verify RHEL 9 will not accept IPv4 source-routed packets.
Check the value of the all "accept_source_route" variables with the following command:
$ sysctl net.ipv4.conf.all.accept_source_route
net.ipv4.conf.all.accept_source_route = 0
If the returned line does not have a value of "0", a line is not returned, or the line is commented out, this is a finding.
Check that the configuration files are present to enable this network parameter.