Details
A firewall is a piece of software that blocks unwanted incoming connections to a system. Apple has posted general documentation about the application firewall. http://support.apple.com/en-us/HT201642 A computer should have a limited number of applications open to incoming connectivity. This rule will check for whether there are more than 10 rules for inbound connections. A firewall minimizes the threat of unauthorized users from gaining access to your system while connected to a network or the Internet. Which applications are allowed access to accept incoming connections through the firewall is important to understand.
Solution
Perform the following to implement the prescribed state: Open System Preferences Select Security & Privacy Select Firewall Select Turn On Firewall Alternatively: Run the following command in Terminal: defaults write /Library/Preferences/com.apple.alf globalstate – int <value> Where <value> is: 1 = on for specific services 2 = on for essential services Impact: The firewall may block legitimate traffic. Applications that are unsigned will require special handling.
Supportive Information
The following resource is also helpful.
This security hardening control applies to the following category of controls within NIST 800-53: System and Communications Protection.This control applies to the following type of system Unix.