Information
RHEL 9 must log IPv4 packets with impossible addresses.
GROUP ID: V-257960
RULE ID: SV-257960r991589
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.
Solution
Configure RHEL 9 to log martian packets on IPv4 interfaces.
Add or edit the following line in a single system configuration file, in the "/etc/sysctl.d/" directory:
net.ipv4.conf.all.log_martians=1
Load settings from all system configuration files with the following command:
$ sudo sysctl --system