Scott's Weblog The weblog of an IT pro focusing on cloud computing, Kubernetes, Linux, containers, and networking

Stupid Tricks With The Mac OS X Firewall

Here’s an interesting way to block access to your Mac OS X system. Simply modify your ipfw script to block traffic to or from the network. When you do this, your Mac will simply fail to log you in, instead presenting you with an endless spinning disk.

The only workaround is to hold down the Shift key while booting (to initiate a Safe Boot), then disable the StartupItem that launches and configures the firewall.

Of course, I speak from personal experience, having added the aforementioned rules in an effort to block spoofed traffic from accessing the loopback interface. Apparently, Mac OS X is different enough from FreeBSD that this advice (advocated on a couple of FreeBSD-related sites I found while searching for ipfw information) is not recommended.

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