Don't do that, unless you want to cause an outage.
On a regular Linux server, turning off IP Forwarding in the IP driver is a perfectly valid recommendation in most cases. It is not appropriate to manually manipulate this value on a Check Point firewall. The Check Point code controls the state of IP forwarding, switching it from the default of 0 to 1 when Check Point services have started, and changing it from 1 to 0 when Check Point services are stopped or policy is unloaded.
If you manually set it to zero, all traffic attempting to transit the firewall will stop working and be dropped by the IP driver just after inspection point I and just before inspection point o. Traffic to and from the firewall itself (i.e. SSH connections to clish/expert mode), HTTPS connections to the Gaia web interface, and firewall management operations will still work, but little else will.
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