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 | 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-75927r1092341_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 |