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ALMA-09-019160 - AlmaLinux OS 9 must not enable IP packet forwarding unless the system is a router.

Information

Routing protocol daemons are typically used on routers to exchange network topology information with other routers. If this capability is used when not required, system network information may be unnecessarily transmitted across the network.

Solution

Configure AlmaLinux OS 9 to not allow IP packet forwarding, unless the system is a router.

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

net.ipv4.conf.all.forwarding = 0
net.ipv4.conf.default.forwarding = 0
net.ipv4.conf.lo.forwarding = 0
net.ipv6.conf.all.forwarding = 0
net.ipv6.conf.default.forwarding = 0
net.ipv6.conf.lo.forwarding = 0

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-269249r1050131_rule, STIG-ID|ALMA-09-019160, Vuln-ID|V-269249

Plugin: Unix

Control ID: 0f5739fa48e7d79eba7d0919f25785f328ee3cf951baa4fa238ccb2f7b351623