RHEL 10 must not enable Internet Protocol version 6 (IPv6) packet forwarding unless the system is a router.

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.

Satisfies: SRG-OS-000420-GPOS-00186, SRG-OS-000142-GPOS-00088

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

Verify RHEL 10 is not performing IPv6 packet forwarding unless the system is a router.

Check the value of the "net.ipv6.conf.all.forwarding" variable with the following command:

$ sudo sysctl net.ipv6.conf.all.forwarding net.ipv6.conf.all.forwarding = 0

If "net.ipv6.conf.all.forwarding" is not set to "0" or is missing, this is a finding.

Configure RHEL 10 to not allow IPv6 packet forwarding unless the system is a router.

Create a configuration file if it does not already exist:

$ sudo vi /etc/sysctl.d/ipv6_forwarding.conf

Add the following line to the file:

net.ipv6.conf.all.forwarding = 0

Reload settings from all system configuration files with the following command:

$ sudo sysctl --system