Commit 7e23309f authored by Tails developers's avatar Tails developers
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Add user docs for MAC spoofing feature.

parent d19828dd
[[!meta title="Enable MAC Changer"]]
[[!meta title="MAC address spoofing"]]
<div class="bug">
# Background
<p>Macchanger is shipped in Tails but there is currently no documented method of
using it.</p>
Every network device (wired, Wi-Fi/wireless, 3G/mobile) has a so
called [[!wikipedia MAC address]], which is a unique identifier used
to address them on the local network. Broadcasting a unique identifier
in this manner introduce a couple of potential privacy issues for
Tails users of which the main one is geographical location tracking;
observing a MAC address at a particular location and time ties the
corresponding device to the same location and time. If the real
identity of the device is known, his or her movements can be
determined. To prevent this one can temporarily change the MAC address
to something random at each boot, which is referred to as "MAC address
spoofing".
<p>[[!tails_todo macchanger desc="See the corresponding ticket."]]</p>
As mentioned above, MAC addresses are normally only used on the
*local* network, and are not supposed to ever reach the Internet.
However, [[!wikipedia captive portals]] may send MAC addresses of
users accessing its services to authentication servers. In any case it
should be noted that the location tracking issue we are talking about
here ha no effect on Internet anonymity, like Tails' web-browser.
</div>
# When to keep MAC address spoofing enabled
First of all, you should know that all network cards, both wired and
wireless, have a unique identifier stored in them called their MAC
address. This address is actually used to address your computer on the
_local_ network. It will usually not go out on the Internet but some
public Wi-Fi connections transmit that MAC address to a central
authentication server, for example when logging into their service.
It is never
useful enabling this option if you are using a public computer – only
use this if you are using a computer that can be linked to you on a
public network.
Tails spoofs the MAC addresses of all network devices **by default**.
It can be disabled by unchecking the corresponding option in Tails
Greeter but in general it is beneficial (or of little or no
consequence) to keep it enabled even if one doesn't care about hiding
one's geographical location.
The reason why this is not always enabled is that is might cause
problems on some networks, so if you experience network problems while
it is enabled you might want try disabling it.
Here are a few examples of when you may want to leave this option
enabled in order to hide you geographical movement while using Tails:
* **Running Tails on your computer on an *open* public network**. With
an "open" public network we mean a network that doesn't require any
kind of registration (with you real identity) in order to access.
* **Running Tails on your computer at a friend's place**. This rule
also applies to "workplace", "school/university" or other locations
you have a strong relationship with. The relationship ties you to
the location any way but sometimes one may want to not be associated
to the place at a *particular* *time*, which makes keeping this
option enabled worthwhile.
# When to disable MAC address spoofing
In some situations MAC address spoofing won't add any benefits but
instead only cause suspicious network activity or connection
issues. Therefore, in the following situations we recommend disabling
this option:
* **Running Tails at home**. The deep association to the location
makes this essentially meaningless, and may cause connection issues
(some ISP-provided modems or routers restrict access based on MAC
addresses).
* **Running Tails on a public computer**, like a library
computer. Since it's not your device, it's not associated to you
directly, so spoofing its MAC address is pointless. Not only that,
it can cause connection issues, or worse, attract suspicion from the
network administrators, so it should really be avoided.
* **Running Tails on your computer using a *restricted* public
network**. As opposed to an "open" public network, with "restricted"
we mean that real identity registration is required.
* **When you experience network issues** due to MAC address
restrictions on the network, or problems with your network devices
(or its driver). In this case MAC address spoofing simply isn't
available, so disabling it is the only way to get a working network
connect. However, disabling it brings back location tracking, so if
that is of importance the only option may be to either use a
different network device, or move to a location without MAC address
restrictions, depending on which of them that caused the issue.
# Other considerations
* We urge users to disable [[!wikipedia Intel AMT]] since it may leak
the *real* MAC address before Tails starts and is able to do
anything about it.
* If you have MAC address spoofing enabled and then reboot your
computer to another operating system (like Windows or Mac OS X) you
will give away your geographical location any way.
* Otherwise "open" public networks should perhaps be considered as
"restricted" in case heavy video surveillance (or similar) is
employed. Note that you may want to consider the memory of employees
or other regulars at the place as surveillance.
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