Stealth mode on the firewall minimizes the threat of system discovery tools while connected to a network or the Internet.
Solution
Perform the following to implement the prescribed state: 1. Open System Preferences 2. Select Security & Privacy 3. Select Firewall Options 4. Select Enable stealth mode Alternatively: 1. Run the following command in Terminal: sudo /usr/libexec/ApplicationFirewall/socketfilterfw --setstealthmode on