Prevent uninvited traffic from receiving a response from the local computer.
Enabling this group policy is the same as clicking the System Preferences > Security > Firewall then clicking Enable Stealth Mode in the Advanced firewall settings.
If you enable this group policy, the local computer will not respond to any network requests, including
ping requests. Because the computer will not reply to ping requests, using this policy may prevent you from using network diagnostic tools that require a response from the local computer.
On Mac OS X Servers, enabling this policy has no effect.
This policy takes effect dynamically at the next group policy refresh interval without rebooting the computer.