Information
The socketfilter firewall is what is used when the firewall is turned on in the Security Preference Pane. In order to appropriately monitor what access is allowed and denied logging must be enabled.
Rationale:
In order to troubleshoot the successes and failures of a firewall, logging should be enabled.
Impact:
Detailed logging may result in excessive storage.
Solution
Run the following command to enable logging of the firewall:
$ sudo /usr/libexec/ApplicationFirewall/socketfilterfw --setloggingmode on
Turning on log mode
Additional Information:
More info http://krypted.com/tag/socketfilterfw/