Detections
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ALMA-09-019380 - AlmaLinux OS 9 must log packets with impossible addresses.

Information

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 AlmaLinux OS 9 to log martian packets.

Create a numbered *.conf file in /etc/sysctl.d/ with the following content:

net.ipv4.conf.all.log_martians = 1
net.ipv4.conf.default.log_martians = 1
net.ipv4.conf.lo.log_martians = 1

The system configuration files need to be reloaded for the changes to take effect. To reload the contents of the files, run the following command:

$ sysctl --system

See Also

https://dl.dod.cyber.mil/wp-content/uploads/stigs/zip/U_CL_AlmaLinux_OS_9_V1R6_STIG.zip

Item Details

Category: CONFIGURATION MANAGEMENT

References: 800-53|CM-6b., CAT|II, CCI|CCI-000366, Rule-ID|SV-269251r1050133_rule, STIG-ID|ALMA-09-019380, Vuln-ID|V-269251

Plugin: Unix

Control ID: 0d8b9f1f8105283e1959244fa1787d0c803587e5901bc7610e6666033123d7bd