We already know that Mac OS is one of the most secure operating systems that exist. However, perhaps you want us be sure that we really have an impenetrable shield. For that, there are some programs, firewalls, anti-virus, etc. which, although they are not usually necessary, under certain conditions can be useful.
One of those programs is GlowWorm. It works by restricting internet access of those programs that we indicate, or by configuring your browser to only permit access to certain urls. Different rules to every mac user account, can be applied so that we can be useful to control our children access to the network, for example.
“Another interesting thing can be avoided is that some applications”call home”. When it detects a connection that has not been previously authorized GlowWorm display a notification with the options of blocking or permission.
It seems a little to LittleSnitch, but with many more configuration options and more information for the user.
The Lite version It is free but you need to register, while the full costs $29.95.