STIGQter: STIG Summary: Cloud Linux AlmaLinux OS 9 Security Technical Implementation Guide Version: 1 Release: 7 Benchmark Date: 01 Jul 2026:

AlmaLinux OS 9 must not accept router advertisements on all IPv6 interfaces.

DISA Rule

SV-269243r1050125_rule

Vulnerability Number

V-269243

Group Title

SRG-OS-000480-GPOS-00227

Rule Version

ALMA-09-018500

Severity

CAT II

CCI(s)

CCI-000366 - Implement the security configuration settings.

Weight

Fix Recommendation

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

Check Contents

Note: If IPv6 is disabled on the system, this requirement is Not Applicable.

Verify AlmaLinux OS 9 does not accept router advertisements on any IPv6 interfaces, unless the system is a router.

Determine if router advertisements are not accepted by using the following command:

$ sysctl -a | grep 'accept_ra '

net.ipv6.conf.all.accept_ra = 1
net.ipv6.conf.default.accept_ra = 1
net.ipv6.conf.enp1s0.accept_ra = 0
net.ipv6.conf.lo.accept_ra = 1

If any of the returned lines are not set to "0" and it is not documented with the information system security officer (ISSO) as an operational requirement, this is a finding.

Vulnerability Number

V-269243

Documentable

False

Rule Version

ALMA-09-018500

Severity Override Guidance

Check Content Reference

Target Key

5664