OL 9 must not accept router advertisements on all IPv6 interfaces.
Overview
| Finding ID | Version | Rule ID | IA Controls | Severity |
| V-271877 | OL09-00-006040 | SV-271877r1092343_rule | CCI-000366 | medium |
| Description | ||||
| An illicit router advertisement message could result in a man-in-the-middle attack. | ||||
| STIG | Date | |||
| Oracle Linux 9 Security Technical Implementation Guide | 2025-05-08 | |||
Details
Check Text (C-271877r1092343_chk)
Note: If IPv6 is disabled on the system, this requirement is Not Applicable.
Verify that OL 9 does not accept router advertisements on all IPv6 interfaces, unless the system is a router.
Determine if router advertisements are not accepted by using the following command:
$ sysctl net.ipv6.conf.all.accept_ra
net.ipv6.conf.all.accept_ra = 0
If the "accept_ra" value is not "0" and is not documented with the information system security officer (ISSO) as an operational requirement, this is a finding.
Fix Text (F-75834r1092342_fix)
Configure OL 9 to not accept router advertisements on all IPv6 interfaces unless the system is a router.
Add or edit the following line in a single system configuration file in the "/etc/sysctl.d/" directory:
net.ipv6.conf.all.accept_ra = 0
Load settings from all system configuration files with the following command:
$ sudo sysctl --system