Do I even need a firewall?
I have a Retina 5K iMac that’s eight months old. Since I turned on the firewall a few weeks ago, there is a warning message after log-on: “Application ccpd wishes to have access, accept or deny”. I always deny permission but I’d like to know what this application is and whether access should be granted. Secondly, is it best to have the firewall on? Clifford Moisey I’m pretty sure ccpd is a Canon printer driver and it is probably trying to open a network connection so it can check for updates. Allowing it is safe (it was already doing this behind your back anyway, before you enabled the firewall) but you shouldn’t normally need the OS X firewall enabled either. Your home broadband router has its own firewall built in and this will almost certainly be more than adequate. You can test this for yourself at grc.com/shieldsup. Run the online diagnostics there, in particular the ‘All Service Ports’ test. If all your ports show green in this test without the OS X firewall turned on then your iMac is invisible to the rest of the internet anyway, and there is nothing to be gained by turning the firewall on.
You really only need an extra firewall on your Mac if you’re running something that specifically expects additional incoming connections (like a web server) or you are concerned about hacking attacks from within your own home network. If you just want to keep out hackers from the wider internet, the router’s firewall is plenty.
If all ports show green in this test then your router’s firewall has a clean bill of health.