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V-271877

CAT II (Medium)

OL 9 must not accept router advertisements on all IPv6 interfaces.

Rule ID

SV-271877r1092343_rule

STIG

Oracle Linux 9 Security Technical Implementation Guide

Version

V1R5

CCIs

CCI-000366

Discussion

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

Check Content

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

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