Silent running on Mac OS X

Occasionally I find myself connected to a public network, like a coffee shop or something, and I don’t want my Mac announcing its file shares, and Bonjouring to every other schmuck on the wifi hotspot. In fact, I don’t even want it to be visible so that it invites port scans and other shenanigans. Of course, in this kind of environment I should be using a VPN, but I digress.

First up, head into System Preferences > Firewall > and block all incoming connections. Make sure you enable stealth mode at the bottom.

Mac OS X firewall configuration

Those paying attention will notice that the firewall won’t automatically block Bonjour as Apple considers it a core service. I don’t. You can disable it using my method (below), or the cludgy Apple support method.

And when you want to enable it again, just use…

Restarting Bonjour to use the new, quieter setting is simple – just restart the mDNSResponder like so…