Mac OS firewall Problem

When you go to the Fire option and unselect "block all incoming connections" and select and application such as "Safari" as an example then select "block incoming" Safari will still continue to communication with the Internet. This has also been placed on Apple support forum called "Firewall Problem" in April-2015. See enclosed.

G'day and welcome to the forums.

Not being familiar with the forum you mentioned, was it suggested you turn on the firewall? Apple's default is to leave the firewall off as your router has the firewall protection. Of course if you use Public WiFi hotspots by all means activte.

What are you trying to accomplish here? If you're looking to simply prevent Safari from working, an easy solution would be to set Safari to use a proxy that points to an invalid URL. With that, Safari will try to connect, ultimately fail, and simply refuse to connect to anything.

Firewall not working

The problem is this is a Firewall fault which should block not only Safari but any other application I choose to set "Block incoming" and it continues in Yosemite.

If you choose any application it will not block incoming data. See youtube "Mac OS Firewall failure"

But ... but ... prevailing wisdom around here is that double firewalls are doubleplus good!

Maybe ... just maybe ... that's not true? Maybe having a software firewall AND a hardware firewall causes conflicts and issues?! :O

Who said anything about a second Firewall?

This post is about a fault with Apple's Firewall not functioning. This occurs not only on Mountain Lion but also Yosemite, I don't know about Maverick as it is not available any more to be downloaded.

when you choose "block incoming" no incoming data should be received.

I don't know how a second firewall play into forcing the acceptance of data to a M.L or Yosemite OS.

Firewalls don't block ALL incoming data, just incoming data that you don't ask for. What you have set up in your image is that Safari is not to respond to unsolicited inputs from outside the firewall. When you fire up Safari, it initiates the communication with the URLs you have chosen as home page, or any other URL you select, so that traffic is seen by the firewall as acceptable (you asked for it, after all). If you want to invoke Safari and NOT connect to the network at all, then do what vansmith suggested and use a proxy and point the default to a nonexistent URL. Here is more reading on how firewalls work:

How Firewalls Work - HowStuffWorks