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RHEL 8 must not accept router advertisements on all IPv6 interfaces.


Overview

Finding ID Version Rule ID IA Controls Severity
V-230541 RHEL-08-040261 SV-230541r599732_rule Medium
Description
Routing protocol daemons are typically used on routers to exchange network topology information with other routers. If this software is used when not required, system network information may be unnecessarily transmitted across the network. An illicit router advertisement message could result in a man-in-the-middle attack.
STIG Date
Red Hat Enterprise Linux 8 Security Technical Implementation Guide 2020-11-25

Details

Check Text ( C-33210r568369_chk )
Verify RHEL 8 does not accept router advertisements on all IPv6 interfaces, unless the system is a router.

Note: If IPv6 is disabled on the system, this requirement is not applicable.

Check to see if router advertisements are not accepted by using the following command:

$ sudo 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-33185r568370_fix)
Configure RHEL 8 to not accept router advertisements on all IPv6 interfaces unless the system is a router with the following commands:

$ sudo sysctl -w net.ipv6.conf.all.accept_ra=0

If "0" is not the system's default value then add or update the following lines in the appropriate file under "/etc/sysctl.d":

net.ipv6.conf.all.accept_ra=0