The presence of "martian" packets (which have impossible addresses) as well as spoofed packets, source-routed packets, and redirects could be a sign of nefarious network activity. Logging these packets enables this activity to be detected.
Check
Verify RHEL 9 logs IPv4 martian packets by default.
Check the value of the accept source route variable with the following command:
$ sudo sysctl net.ipv4.conf.default.log_martians
net.ipv4.conf.default.log_martians = 1
If the returned line does not have a value of "1", 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.