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Changing your MAC address

Why change your MAC address?

If you are interested in keeping your online identity anonymous, then changing the unique MAC address of your computer each time you connect to a network is one way to aid in this process. This is particularly useful if you tend to move around to different locations with your computer, such as to cafes, libraries, and airports.

What is a MAC address?

First of all, a MAC address is not to be confused with macOS, the current operating system for Apple computers.

MAC stands for media access control. Your computer usually has two MAC addresses, each of which are unique to your device. One address is used when you plug in an Ethernet cable and the other is visible when it connects to a WiFi network. If you sit down at a cafe with your laptop and you have WiFi enabled, the laptop will broadcast its MAC address as it searches for a WiFi network to connect to.

How your MAC address can reveal your identity

Computer manufacturers keep lists of the MAC addresses corresponding to all the devices they've built. Buying a computer with a credit card (which is tied to your identity) makes it possible to link your purchase to a unique MAC address.

If someone decides to track your MAC address, it would be easy to trace your physical movements. Remember, every time your computer communicates with a WiFi connection, your computer is revealing its location.

But even if directly linking you to a MAC address is not likely, it is still possible for someone to collect a series of locations and times at which your computer has connected to various WiFi networks and, in the end, connect them to you.

Changing your computer's MAC address

MAC Changer is a utility program that will automatically change your MAC address each time your computer connects to a network.

To install this program, you will need to run the following command in your terminal.

Installing on Linux or Debian
apt-get install macchanger

Installing on macOS [this app has been removed from brew - we are looking for a new version 2018-09-12]
brew install macchanger
(if you do not have brew installed, install here)

During installation, you will be prompted with the following screen asking if you'd like to automatically change your MAC address every time your network interface goes online. Choose Yes and you're set!

You can leave MAC Changer to do the work for you. But if you ever want to manually change your MAC address whenever you'd like, keep reading.

Manually changing your MAC address

First, you need to figure out what your Ethernet or wireless network is named. To do this, open a terminal and run the command ifconfig.

In the example below, we have found the computer's Ethernet which is named eth0 (first red circle). The corresponding MAC address is 00:16:3e:5e:6c:1a (next to the second red circle).

Once you have this information, run the following terminal command to show your current MAC address (if necessary, change "eth0" to reflect your setup):
macchanger eth0 -s

To assign a new and random MAC address, run this command (again, change "eth0" if needed):
sudo macchanger eth0 -r