Information
While in Stealth mode the computer will not respond to unsolicited probes, dropping that traffic. http://support.apple.com/en-us/HT201642 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: Open System Preferences Select Security & Privacy Select Firewall Options Select Enable stealth mode Alternatively: Run the following command in Terminal: sudo /usr/libexec/ApplicationFirewall/socketfilterfw --setstealthmode on Impact: Traditional network discovery tools like ping will not succeed. Other network tools that measure activity and approved applications will work as expected.