According to the vendor website LittleSnitch is “a firewall that intercepts unwanted connection attempts, and lets you decide how to proceed”.
It is really common, and a best practice, to replace Mac OS X default firewall with a more advanced firewall like Little Snitch.
This chapter is dedicated to configuring Little Snitch 3.
It is suggested to enable an advanced mode to all event’s details. Start Little Snitch. Go to:
Preferences ⇒ Alert
Set “Detail Level” to “Show Full Details”.
By default automatic update check is disabled, it is suggested to enable it. Start Little Snitch. Go to:
Preferences ⇒ Update
Check “Automatic check for updates” and set it to “Daily”.
Scripting access is a security risk because a malicious software could be able to add rules to LittleSnitch and/or modify its behavior. It is suggested to disable it, it is usually disabled by default. Start Little Snitch. Go to:
Preferences ⇒ Security
Un-check “Allow GUI Scripting access to Little Snitch”. Un-check “Allow Scripting Additions”.