Sever a Mac’s Ethernet Access for Nighttime Security

If you leave your Mac powered up 24x7, one way to ensure the security of your Mac while you sleep is to sever the Ethernet connection with a simple click. Here’s how to do it.

In the Mac OS X System Preferences, there is a setting for “Network.” That’s where we create various network configurations, for example, a wired Ethernet or a wireless AirPort/Wi-Fi connection. Here’s what mine looks like when I’m on a wired connection to my router:

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Normal Setting

Once various settings are created and named, there’s a shortcut to access each one under the Apple menu: Locations. Here’s a list of locations that I have defined and can easily select:

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Location Popup

What I do to ensure additional security while I’m sleeping is to create a new location that completely severs my Internet connection. I did that with the Location Popup at the top of the Network panel, in the item: Edit Locations…

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Edit Locations: Add new with “+” button

Click on the “+” button in the popup to create a new location entry. I’ve created a location called “Off the Air.” The trick is to look at “Configure IPv4:” and use the “Off” setting. Here’s how it looks when done:

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Ethernet is Inactive

Before I go to bed, I simply select this Location, and my Mac can continue to manage its logs at night, do Time Machine updates, but no one can touch it from the Internet. This is especially helpful if you have the Energy Saver setting set to wake for a network connection during the daytime if, say, you’re using screen sharing from another room. This “Off The Air” setting will override the “Wake for network access” setting once activated.

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“Wake for network access” can help or undo your intentions


This procedure may seem a bit paranoid, but it makes me feel better knowing that, while I’m asleep, my Internet connection is completely severed at the lowest hardware level. OF course, I could turn off the iMac when I’m done in the evening, but it’s a pain to reboot every morning. Anyway, UNIX boxes like to stay on. Or I could put the Mac to sleep, but for personal reasons, I like letting the UNIX-based Mac run 24x7 (with screensaver!) but having the finality of severing the Ethernet connection while I snooze myself.

This technique may be of technical interest to some for other reasons, and it’s not for everyone. But it is nice to have lots of security options, and this is just one trick you may want to be aware of for future use.