3.1.1 Ensure IP forwarding is disabled - ipv6 /etc/sysctl.conf /etc/sysctl.d/*

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/3399

Item Details

Category: CONFIGURATION MANAGEMENT, SYSTEM AND SERVICES ACQUISITION

References: 800-53|CM-2, 800-53|CM-6, 800-53|CM-7, 800-53|CM-7(1), 800-53|CM-9, 800-53|SA-3, 800-53|SA-8, 800-53|SA-10, CSCv6|3, CSCv6|11, CSCv7|5.1

Plugin: Unix

Control ID: 165cfd00d5ccd0d731e0baead8797dd4ad46e58a81e20b369bf4017e36c2d816