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.
Rationale:
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 Options
Select unneeded rules
Select the minus sign below to delete them
Alternatively:
Edit and run the following command in Terminal to remove specific applications:
/usr/libexec/ApplicationFirewall/socketfilterfw –remove
Where is the one to be removed
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.