3.1.1 Ensure IP forwarding is disabled - sysctl

Information

The net.ipv4.ip_forward flag is used to tell the system whether it can forward packets or not.

Rationale:

Setting the flag 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

Run the following commands to set the active kernel parameters:

# sysctl -w net.ipv4.ip_forward=0
# sysctl -w net.ipv4.route.flush=1

See Also

https://workbench.cisecurity.org/files/3738

Item Details

Category: SYSTEM AND COMMUNICATIONS PROTECTION

References: 800-53|SC-7(12)

Plugin: Unix

Control ID: 63dfff3ca6436424837ee5997583a1f3be5cd2ec9cf5366d9183e50a9a9623fb