Make Windows Firewall tell you when it is blocking something

Depending on how Windows Firewall is configured, it may or may not tell you that it blocked something. If you want to configure it to notify you when it blocks something, just do one of the following.

netsh firewall set notifications ENABLE ALL

or

Use regedit and set the value to zero

HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\WindowsFirewall\DomainProfile\DisableNotifications = 0

You have to stop and start the Windows Firewall service for these settings to take effect. A reboot would also do the trick. :)