Ensure IP forwarding is disabled - /etc/sysctl

Information

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 the /etc/sysctl.conf 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://www.cisco.com/c/en/us/td/docs/security/firepower/623/configuration/guide/fpmc-config-guide-v623.html

Item Details

Category: SYSTEM AND COMMUNICATIONS PROTECTION

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

Plugin: Unix

Control ID: eaa9ebbeb91b8b97e7ab5e560cc02004c47016ae3f72f32a57acc31f1a9f66d9