RHEL 9 must not enable IPv6 packet forwarding unless the system is a router.
Severity | Group ID | Group Title | Version | Rule ID | Date | STIG Version |
|---|---|---|---|---|---|---|
| medium | V-257974 | SRG-OS-000480-GPOS-00227 | RHEL-09-254025 | SV-257974r991589_rule | 2025-02-27 | 2 |
| Description |
|---|
| IP forwarding permits the kernel to forward packets from one network interface to another. The ability to forward packets between two networks is only appropriate for systems acting as routers. |
| ℹ️ Check |
|---|
| Verify RHEL 9 is not performing IPv6 packet forwarding, unless the system is a router. Note: If IPv6 is disabled on the system, this requirement is Not Applicable. Check that IPv6 forwarding is disabled using the following commands: $ sudo sysctl net.ipv6.conf.all.forwarding net.ipv6.conf.all.forwarding = 0 If the IPv6 forwarding value is not "0" and is not documented with the information system security officer (ISSO) as an operational requirement, this is a finding. Check that the configuration files are present to enable this network parameter. $ sudo /usr/lib/systemd/systemd-sysctl --cat-config | egrep -v '^(#|;)' | grep -F net.ipv6.conf.all.forwarding | tail -1 net.ipv6.conf.all.forwarding = 0 If "net.ipv6.conf.all.forwarding" is not set to "0" or is missing, this is a finding. |
| ✔️ Fix |
|---|
| Configure RHEL 9 to not allow IPv6 packet forwarding, 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.forwarding = 0 Load settings from all system configuration files with the following command: $ sudo sysctl --system |