RHEL 9 must prevent IPv6 Internet Control Message Protocol (ICMP) redirect messages from being accepted.
An XCCDF Rule
Description
ICMP redirect messages are used by routers to inform hosts that a more direct route exists for a particular destination. These messages modify the host's route table and are unauthenticated. An illicit ICMP redirect message could result in a man-in-the-middle attack.
- ID
- SV-257976r991589_rule
- Version
- RHEL-09-254035
- Severity
- Medium
- References
- Updated
Remediation Templates
A Manual Procedure
Configure RHEL 9 to prevent IPv6 ICMP redirect messages from being accepted.
Add or edit the following line in a single system configuration file, in the "/etc/sysctl.d/" directory:
net.ipv6.conf.default.accept_redirects = 0