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ALMA-09-018500 - AlmaLinux OS 9 must not accept router advertisements on all IPv6 interfaces.

Information

An illicit router advertisement message could result in a man-in-the-middle attack.

Solution

Configure AlmaLinux OS 9 to not accept router advertisements on all IPv6 interfaces unless the system is a router.

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

net.ipv6.conf.all.accept_ra = 0
net.ipv6.conf.default.accept_ra = 0
net.ipv6.conf.lo.accept_ra = 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-269243r1050125_rule, STIG-ID|ALMA-09-018500, Vuln-ID|V-269243

Plugin: Unix

Control ID: 60a16e1d633b96996b8386ba84e05fbc3acb3ebd743e02aea3476b9901d16c1a