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