TOSS 5 must not enable Internet Protocol version 4 (IPv4) packet forwarding unless the system is a router.

Routing protocol daemons are typically used on routers to exchange network topology information with other routers. If this capability is used when not required, system network information may be unnecessarily transmitted across the network.

Verify TOSS 5 is not performing IPv4 packet forwarding unless the system is a router using the following command:

$ sudo sysctl net.ipv4.conf.all.forwarding

net.ipv4.conf.all.forwarding = 0

If the IPv4 forwarding value is not "0" and is not documented with the information system security officer (ISSO) as an operational requirement is missing, this is a finding.

Configure TOSS 5 to not allow IPv4 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.ipv4.conf.all.forwarding = 0

Load settings from all system configuration files using the following command:

$ sudo sysctl --system