Title

The system must log Martian packets. (Cat III impact)

Discussion

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 Content

The status of the "net.ipv4.conf.all.log_martians" kernel parameter can be queried by running the following command: $ sysctl net.ipv4.conf.all.log_martians net.ipv4.conf.all.log_martians = 1 $ grep net.ipv4.conf.all.log_martians /etc/sysctl.conf /etc/sysctl.d/* net.ipv4.conf.all.log_martians = 1 If "net.ipv4.conf.all.log_martians" 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 "1", this is a finding.

Fix Text

To set the runtime status of the "net.ipv4.conf.all.log_martians" kernel parameter, run the following command: # sysctl -w net.ipv4.conf.all.log_martians=1 Set the system to the required kernel parameter by adding the following line to "/etc/sysctl.conf" or a config file in the /etc/sysctl.d/ directory (or modify the line to have the required value): net.ipv4.conf.all.log_martians = 1 Issue the following command to make the changes take effect: # sysctl --system

Additional Identifiers

Rule ID: SV-217917r603264_rule

Vulnerability ID: V-217917

Group Title: SRG-OS-000480

Expert Comments

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