3.1.1 Ensure IP forwarding is disabled - ipv6 sysctl

Information

The net.ipv4.ip_forward and net.ipv6.conf.all.forwarding flags are used to tell the system whether it can forward packets or not.
Rationale:
Setting the flags to 0 ensures that a system with multiple interfaces (for example, a hard proxy), will never be able to forward packets, and therefore, never serve as a router.

Solution

Set the following parameter in /etc/sysctl.conf or a /etc/sysctl.d/* file:
net.ipv4.ip_forward = 0
net.ipv6.conf.all.forwarding = 0
Run the following commands to set the active kernel parameters:
# sysctl -w net.ipv4.ip_forward=0
# sysctl -w net.ipv6.conf.all.forwarding=0
# sysctl -w net.ipv4.route.flush=1
# sysctl -w net.ipv6.route.flush=1

See Also

https://workbench.cisecurity.org/files/2429

Item Details

Category: SYSTEM AND COMMUNICATIONS PROTECTION

References: 800-53|SC-7(12), CSCv6|3, CSCv6|11, CSCv7|5.1

Plugin: Unix

Control ID: c9f48e5682bc25de2a82f78a513219cc4bbde9843187083971c4367d8a4c3e48