AlmaLinux OS 9 must log packets with impossible addresses.
Severity | Group ID | Group Title | Version | Rule ID | Date | STIG Version |
|---|---|---|---|---|---|---|
| medium | V-269251 | SRG-OS-000480-GPOS-00227 | ALMA-09-019380 | SV-269251r1050133_rule | 2025-02-20 | 1 |
| Description |
|---|
| 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. |
| ℹ️ Check |
|---|
| Verify AlmaLinux OS 9 logs martian packets. Check the value of the "log_martians" variables with the following command: $ sysctl -a | grep log_martians net.ipv4.conf.all.log_martians = 1 net.ipv4.conf.default.log_martians = 1 net.ipv4.conf.enp1s0.log_martians = 1 net.ipv4.conf.lo.log_martians = 1 If the returned lines do not all have a value of "1", this is a finding. |
| ✔️ Fix |
|---|
| 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 |