Download the current release of the Who's There? Firewall Advisor

Open Door Networks 
View, understand and react to access attempts detected by your firewall
Provides advice and helps you take action to combat access attempts
Enhances our DoorStop X Firewall and others
Available standalone or as part of our integrated Security Suite
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You can download an evaluation version of Who's There? below. The current version of Who's There? is 2.3 and requires Mac OS X 10.4.11 or later (10.5 or later recommended). The evaluation version of Who's There? is fully functional and will run for 30 days before expiring.

Who's There? icon
Download the Who's There? Firewall Advisor

You can download other products from the DoorStop X Security Suite, or the whole Suite, here.