[pt-br] Update translation bits.

[tails-test.git] / wiki / src / support / faq.mdwn

[[!meta title="Frequently asked questions"]]

[[!toc levels=2]]

<a id="project"></a>

Other useful resources
======================

  - [The Tor Project: FAQ](https://www.torproject.org/docs/faq.html.en)
  - [The Tor Project: Stack Exchange, question & answer site](https://tor.stackexchange.com/)

Tails project
=============

<a id="relationship_with_tor"></a>

What is the relationship between Tor and Tails?
-----------------------------------------------

See our explanation about [[why does Tails use Tor|doc/about/tor#relationship]].

<a id="debian"></a>

Why is Tails based on Debian and not on another distribution?
-------------------------------------------------------------

We are deeply rooted and involved in Debian. The friendships, relationships, and
technical expertise we have in Debian have many benefits for Tails, and we are
not ready to build the same relationship with Ubuntu, OpenBSD, or any other
distribution. See our statement about our
[[contribute/relationship_with_upstream]] for details.

See also the article [Why there are so many Debian
derivatives](http://upsilon.cc/~zack/blog/posts/2011/09/why_there_are_so_many_debian_derivatives/)
by Stefano Zacchiroli.

<a id="ubuntu"></a>

Why isn't Tails based on Ubuntu?
--------------------------------

First, see the answer to the [[previous question|faq#debian]].

0. The rapid development cycle of Ubuntu would be too fast for Tails.
0. Ubuntu adds features in ways that we find dangerous for privacy. For example
   Ubuntu One
   ([partly discontinued](http://blog.canonical.com/2014/04/02/shutting-down-ubuntu-one-file-services/))
   and the [Amazon ads and data leaks](https://www.eff.org/deeplinks/2012/10/privacy-ubuntu-1210-amazon-ads-and-data-leaks).
0. Ubuntu is led by a company that takes most of the important decisions and has
   the power to make them happen.
0. We usually ship kernels and video drivers from [Debian
   backports](http://backports.debian.org/). The result
   is comparable to Ubuntu in terms of support for recent hardware.
0. We think that the general quality of the maintenance work being done on
   packages matters from a security perspective. Debian maintainers generally are
   experts in the fields their packages deal with; while it is generally not
   the case outside of the limited number of packages Ubuntu officially supports.
0. We are actively working on adding
   [[AppArmor|blueprint/Mandatory_Access_Control]] support to Tails; a security
   framework that is already used in a few Ubuntu applications.
0. We are also working on adding compiler hardening options to more Debian
   packages included in Tails; another security feature that Ubuntu already
   provides.

<a id="website"></a>

Tails website
=============

<a id="ssl_certificate"></a>

Why does tails.boum.org rely on a commercial SSL certificate?
-------------------------------------------------------------

HTTPS provides encryption and authentication on the web. The standard
authentication mechanism through SSL certificates is centralized and based on
commercial or institutional certificate authorities. This mechanism has proven
to be susceptible to various methods of compromise. See our [[warning about
man-in-the-middle attacks|doc/about/warning#man-in-the-middle]].

Still, we use HTTPS on our website and rely on a commercial certificate even if
we acknowledge those security problems.

1. Providing no HTTPS and no kind of encryption would be a worse option.

2. Providing a self-signed certificate or another marginally supported
authentication mechanism would not work for the majority of users. Modern
browsers display very strong warnings when facing a self-signed certificate, and
many people would think the website is broken while it is not.

We prefer to provide weak security, using a commercial certificate, that still
works for most people. At the same time, we make clear this security is limited
and encourage stronger ways of verifying the authenticity of Tails once
downloaded.  See our documentation on [[verifying the ISO|download#verify]].

<a id="hardware"></a>

Hardware compatibility
======================

<a id="64-bit"></a>

Does Tails work with 64-bit processors?
---------------------------------------

Yes. Tails automatically detects the type of processor of the computer and loads
a 32-bit or a 64-bit kernel accordingly.

<a id="arm"></a>

Does Tails work on ARM architecture, Raspberry Pi, or tablets?
--------------------------------------------------------------

For the moment, Tails is only available on the x86 and x86_64 architectures.
The Raspberry Pi and many tablets are based on the ARM architecture. Tails does
not work on the ARM architecture so far.

Look for a tablet with an AMD or Intel processor. Try to verify its
compatibility with Debian beforehand, for example make sure that the Wi-Fi
interface is supported.

<a id="installation"></a>

Installation
============

<a id="install_permanently"></a>

Can I install Tails permanently onto my hard disk?
--------------------------------------------------

This is not possible using the recommended installation methods. Tails is
designed to be a live system running from a removable media: DVD, USB stick or
SD card.

This is a conscious decision as this mode of operation is better for what we
want to provide to Tails users: amnesia, the fact that Tails leaves no traces on
the computer after a session is closed.

<a id="browser"></a>

Web browser
===========

<a id="javascript"></a>

Why is JavaScript enabled by default in the Tor browser?
--------------------------------------------------------

Many websites today require JavaScript to work correctly. As a consequence
JavaScript is enabled by default in Tails to avoid confusing many users. But
the [[Torbutton|doc/anonymous_internet/Tor_browser#torbutton]] extension,
included in Tails, takes care of blocking dangerous JavaScript functionalities.

Tails also includes the [[NoScript|doc/anonymous_internet/Tor_browser#noscript]]
extension to optionally disable more JavaScript. This might improve
security in some cases. However, if you disable JavaScript, then the
[[fingerprint|doc/about/fingerprint]] of your browser will
differ from most Tor users. This might break your anonymity.

We think that having JavaScript enabled by default is the best possible
compromise between usability and security in this case.

<a id="add-ons"></a>

Can I install other add-ons in the browser?
-------------------------------------------

Installing add-ons in the browser might break the security built in Tails.

Add-ons can do many things within the browser, and even if all the networking goes
through Tor, some add-ons might interact badly with the rest of the
configuration or leak private information.

1. They can track and reveal information about your browsing behaviour, browsing
history, or system information, either on purpose or by mistake.

2. They can have bugs and security holes that can be remotely exploited by an
attacker.

4. They can have bugs breaking the security offered by other add-ons, for example
Torbutton, and break your anonymity.

5. They can break your anonymity by making your browsing behaviour
distinguishable amongst other Tails users.

Unless proven otherwise, no add-on, apart from the ones already
included in Tails, have been seriously audited and should be
considered safe to use in this context.

<div class="next">
  <ul>
    <li>[[Warnings about persistence|doc/first_steps/persistence/warnings#index3h1]]</li>
    <li>[[Browsing the web with Iceweasel|doc/anonymous_internet/Tor_browser]]</li>
    <li>[[Can I hide the fact that I am using Tails?|doc/about/fingerprint/]]</li>
  </ul>
</div>

<!--
XXX: Push that information to the browser documentation?
XXX: Check https://www.torproject.org/torbutton/torbutton-faq.html.en#recommendedextensions
-->

<a id="flash"></a>

Can I view websites using Adobe Flash with Tails?
-------------------------------------------------

Adobe Flash Player is not included in Tails for several reasons:

  - It is proprietary software which prevents us from legally including it in
    Tails.
  - It is closed source and so we have no idea of what it really does.
  - It has a very long history of serious security vulnerabilities.
  - It is known to favor privacy invasive technologies such as [[!wikipedia Local_shared_object]].
  - Adobe only maintains their GNU/Linux Flash plugin for Google Chrome.

We have considered including open-source alternative software to Adobe
Flash, such as [Gnash](http://www.gnu.org/software/gnash/), but it is
not the case yet, see [[!tails_ticket 5363]].

But you can already watch HTML5 videos with the Tor browser.

<a id="anonymity_test"></a>

How to analyse the results of online anonymity tests?
-----------------------------------------------------

Fingerprinting websites such as <https://panopticlick.eff.org/> or
<https://ip-check.info/> try to retrieve as much information as possible from
your browser to see if it can be used to identify you.

As explained in our documentation about
[[fingerprinting|doc/about/fingerprint]], Tails provides anonymity on the web by
making it difficult to distinguish a particular user amongst all the users of
Tails and the Tor Browser Bundle (TBB).

So, the information retrieved by such fingerprinting websites is not harmful for
anonymity in itself, as long as it is the same for all Tor users.

For example, the user-agent property of the browser was set to `Mozilla/5.0
(Windows; U; Windows NT 6.1; en-US; rv:1.9.2.3) Gecko/20100401 Firefox/3.6.3`,
as of Tails 0.21 and TBB 2.3.25-13. This value preserves your anonymity even if
the operating system installed on the computer is Windows NT and you usually run
Firefox. On the other hand, changing this value makes you distinguishable from
others Tor users and breaks your anonymity.

Furthermore, we verify the result of those websites before each release, see our
[[test suite|contribute/release_process/test]].

<a id="java"></a>

Is Java installed in the Tor browser?
---------------------------------------

Tails does not include a Java plugin in its browser because it could break your anonymity.

<a id="unsafe_browser"></a>

Can I use the Unsafe Browser to browse the web or download files?
-----------------------------------------------------------------

No. The Unsafe Browser is only included in Tails as a tool to log into [[captive
portals|doc/anonymous_internet/unsafe_browser]]. It is not meant to be used as a
regular web browser. As a consequence, the files that you might download using
the Unsafe Browser are not accessible by your user.

<a id="persistence"></a>

Persistence
===========

<a id="persistent_features"></a>

Can I save my custom settings?
------------------------------

<em>&hellip; like language, keyboard layout, background image, toolbar position,
browser settings, touchpad preferences, etc.</em>

By default Tails does not save anything from one working session to another.
Only the persistent volume allows you to reuse data across different working
sessions. See the list of existing [[persistent
features|doc/first_steps/persistence/configure#features]].

We are frequently requested to add new persistent features but we are usually
busy working on other priorities. See our [open
tickets](https://labs.riseup.net/code/projects/tails/issues?query_id=122)
about persistence. Any bit of help [[is welcome|contribute/how/code]].

<a id="luks"></a>

How strong is the encryption of the persistent volume and LUKS?
---------------------------------------------------------------

Tails uses LUKS to encrypt the persistent volume. This is the same technique as
the one we recommend for [[creating and using encrypted
volumes|doc/encryption_and_privacy/encrypted_volumes]] in general.

LUKS is a very popular standard for disk encryption in Linux. LUKS is the
default technique for full-disk encryption proposed by many distribution,
including Debian and Ubuntu, when installing a regular system.

Currently the default cipher is `aes-cbc-essiv:sha256` with a key size of 256
bits.

To understand better how persistence work, see our [[design
document|contribute/design/persistence]].

<a id="recover_passphrase"></a>

Is it possible to recover the passphrase of the persistent volume?
------------------------------------------------------------------

No. The encryption of the persistent volume is very strong and it is not
possible to recover the passphrase of the persistent volume. If the passphrase
is weak enough, an attacker, using a brute force attack, could try many
possible passphrases and end up guessing your passphrase.

<a id="networking"></a>

Networking
==========

<a id="vpn"></a>

Can I use Tails with a VPN?
---------------------------

Three possible scenarios need to be distinguished:

  - Using a VPN instead of Tor
  - Using a VPN to connect to Tor (VPN before Tor)
  - Connecting to a VPN using Tor (VPN after Tor)

For more information, see our [[blueprint on VPN
support|blueprint/vpn_support/]].

### Using a VPN instead of Tor

It is a very [[fundamental assumption of Tails|about#tor]] to force all outgoing
traffic to anonymity networks such as Tor or I2P. VPN are not anonymity
networks, because the administrators of the VPN can know both where you are
connecting from and where you are connecting to. Tor provides anonymity by
making it impossible for a single point in the network to know both the origin
and the destination of a connection.

### Using a VPN to connect to Tor (VPN before Tor)

In some situations, you might be forced to use a VPN to connect to the Internet,
for example by your ISP. This is currenlty not possible using Tails. See
[[!tails_ticket 5858]].

[[Tor bridges|doc/first_steps/startup_options/bridge_mode]] can also be useful
to bypass the limitations imposed by your ISP.

### Connecting to a VPN using Tor (VPN after Tor)

In some situtations, it can be useful to connect to a VPN through Tor:

  - To access services that block connections coming from Tor.
  - To access ressources only available inside a VPN, for example at your
    company or University.

This is currenlty not possible easily using Tails.

<a id="mac_address"></a>

Does Tails change the MAC address of my network interfaces?
-----------------------------------------------------------

Starting from Tails 0.23, [[MAC
spoofing|doc/first_steps/startup_options/mac_spoofing]] is enabled by default
on all interfaces.

<a id="dns"></a>

How does the DNS resolution work in Tails?
------------------------------------------

See our [[design document|contribute/design/Tor_enforcement/DNS]] on this topic.

<a id="htp"></a>

Why does Tails automatically connect to several websites when starting?
-----------------------------------------------------------------------

Tor and I2P require the system clock to be well synchronized in order to work
properly. When starting Tails, a notification is displayed while the clock is
being synchronized.

This synchronization is made by sending HTTPS queries through Tor to severals
websites and deducing a correct time from their answers. The list of websites
that could be queried in this process can be found in `/etc/default/htpdate`.

See also our [[design document|contribute/design/Time_syncing]] on this topic.

<a id="software"></a>

Software not included in Tails
==============================

<a id="new_software"></a>

Can my favourite software be included in Tails?
-----------------------------------------------

First of all, make sure that this software is already available in Debian, as
this is a requirement to be included in Tails. Adding to Tails software which is
not in Debian imply an additional workload that could compromise the
sustainability of the project. On top of that, being in Debian brings many
advantages:

  - It is included in the Debian process for security updates and new versions.
  - It is authenticated using OpenPGP signatures.
  - It is under the scrutiny of the Debian community and its many users and
    derivatives, including Ubuntu.

To check whether a software is in Debian, search for it on
<https://packages.debian.org/>. If it is not yet available in Debian, you should
ask its developers why it is not the case yet.

Second, this software might not be useful to accomplish our design goals. Refer
to our [[design documents|contribute/design]] to understand which are
the intended use cases, and the assumptions on which Tails is based.

We also try to limit the amount of software included in Tails, and we only add
new software with a very good reason to do so:

  - We try to limit the growth of the ISO image and automatic upgrades.
  - More software implies more security issues.
  - We avoid proposing several options to accomplish the same task.
  - If a package needs to be removed after its inclusion, for example because of
    security problems, then this might be problematic as users might rely on it.

After considering all this, if you still think that this software is a good
candidate to be included in Tails, please [[explain us|/contribute/talk]] your
proposal.

<div class="tip">

If a software is not included in Tails, but is included in Debian, you can use
the [[additional
software|doc/first_steps/persistence/configure#additional_software]] feature of
the persistent volume to install it automatically at the beginning of each
working session.

</div>

Here is some of the software we are often asked to include in Tails:

  - **bitmessage**: not in Debian
  - **torchat**: see [[!tails_ticket 5554]]
  - **bitcoin**, **electrum**: see [[!tails_ticket 6739]]

<a id="bittorrent"></a>

Can I download using BitTorrent with Tails?
-------------------------------------------

Tails does not ship any BitTorrent software and is unlikely to do so in the
future.

The problem with using BitTorrent over Tor is double:

  - It is technically hard to do it properly, see:
    <https://blog.torproject.org/blog/bittorrent-over-tor-isnt-good-idea>.
  - It harms the network, see:
    <https://blog.torproject.org/blog/why-tor-is-slow>.

We have relatively vague [[!tails_ticket 5991 desc="plans to improve
on this situation"]].

<a id="desktop"></a>

Desktop environment
===================

<a id="timezone"></a>

Why is the time set wrong?
--------------------------

When Tails starts, the system timezone is set to UTC (Greenwich time). So, this time
might be a few hours in the future if you are West from the United
Kingdom, or in the past if you are East from the UK. The minutes
should be accurate.

We do this for anonymity reasons: if some application reveals your actual
timezone, it might help identifying who you are.

Having all Tails users set to the same timezone, makes it more difficult to
distinguish you amongst all the other Tails users.

<div class="note">

We are working on a custom clock applet with configurable timezone. See
[[!tails_ticket 6284]].

</div>

<a id="misc"></a>

Other security issues
=====================

<a id="compromised_system"></a>

Is it safe to use Tails on a compromised system?
------------------------------------------------

Tails runs independently from the operating system installed on the computer.
So, if the computer has only been compromised by software, running from inside
your regular operating system (virus, trojan, etc.), then it is safe
to use Tails. This is true as long as Tails itself has been installed
using a trusted system.

If the computer has been compromised by someone having physical access to it and
who installed untrusted pieces of hardware, then it might not be safe to use
Tails.

<a id="integrity"></a>

Can I verify the integrity of a Tails device?
---------------------------------------------

It is not possible to verify the integrity of a Tails device when running Tails
from this same device. This would be like asking to someone whether she is a
liar; the answer of a true liar would always be "no".

- To verify the integrity of a DVD from a separate trusted system, you can
  verify the signature of the ISO image as documented in [[verify the ISO image
  using the command line|doc/get/verify_the_iso_image_using_the_command_line]]
  against the DVD itself.

- There is no documented method of verifying the integrity of a USB stick or SD
  card installed using <span class="application">Tails
  Installer</span>. However, if you have another trusted Tails device,
  you can [[clone it onto the untrusted device|doc/first_steps/upgrade]] to
  reset it to a trusted state.

<a id="reuse_memory_wipe"></a>

Can I use the memory wipe feature of Tails on another operating system?
-----------------------------------------------------------------------

The memory wipe mechanism that Tails uses on shutdown to [[protect against cold
boot attacks|doc/advanced_topics/cold_boot_attacks]] is not yet available in
other Linux distributions. In the future, we would like to package it for
Debian.

If you want to implement this feature outside of Tails, have a look at the
corresponding [[design documentation|contribute/design/memory_erasure]].

<a id="new_identity"></a>

Is it safe to use the new identity feature of Vidalia?
------------------------------------------------------

In our [[warning page|doc/about/warning#identities]] we advice to restart Tails
every time that you want to use a different contextual identity. The <span
class="guilabel">New Identity</span> feature of <span
class="application">Vidalia</span> forces Tor to use new circuits but only for
new connections. The two main drawbacks of this technique are:

- The circuits used by connections that remain open might not be changed: for
example, a circuit used to connect to an open webpage or to an instant
messaging server.

- Each application might contain information that can identify you,
independently of the Tor circuit that are used. For example, the browser might
contain cookies from previous websites, <span
class="application">[[Pidgin|doc/anonymous_internet/pidgin]]</span> will reuse the
same nickname by default, etc.

Tails is a full operating system, so a *new identity* should be thought on a
broader level than only switching Tor circuits.

<a id="truecrypt"></a>

Can I use TrueCrypt with Tails?
-------------------------------

Yes, but TrueCrypt needs to be activated when starting Tails, see our
[[documentation|doc/encryption_and_privacy/truecrypt]]. Tails includes TrueCrypt
only for backward compatibility and we are working on [[choosing a free software
as replacement|blueprint/replace_truecrypt]] to open TrueCrypt volumes.

Furthermore, [TrueCrypt is now discontinued](http://truecrypt.sourceforge.net/)
and its development team recommends against using it. We recommend using other
[[encryption tools|doc/encryption_and_privacy/encrypted_volumes]] such as
[[LUKS|faq#luks]].

<a id="boot_statistics"></a>

Does Tails collect information about its users?
-----------------------------------------------

When Tails starts, two HTTPS requests are made automatically to our website
through Tor:

- A security check is performed to know if security issues have been announced
  for this version of Tails. The language of the working session is passed along
  with this request to display the notification in the preferred language of the
  user.
- [[<span class="application">Tails Upgrader</span>|doc/first_steps/upgrade]]
  checks for newer versions. The version of the running Tails is passed along
  with this request.

We believe it is important to notify the user of known security issues and newer
versions. We calculate statistics based on the security check to know how many times
Tails has been started and connected to Tor. Those statistics are published in
our [[monthly reports|news]].

<!--
<rawmaterial>

Proxy
-----

How_do_you_chain_a_proxy_after_TOR___63__
Next_Tails_version_should_have_proxychains_for_socks_after_exit_node
alternative_way_to_connect_to_web
featurerequest:_proxychains

easy way to chain a SOCKS5 proxy after the hop off the exit node of TOR.

I need to  hide the fact that I'm coming from TOR, because many websites block tor.

I have found some websites that explain how to create an SSH tunnel, but using the terminal is above my level of skills :)

It should be possible to use a program like Proxify to chain a proxy, but I
don't know if this creates conflicts, and I don't know how to install a program
that can run of the persistent volume.

Surely there is someone who can simply give us a paragraph of text to enter into
the polipo config file ( where i add the ip address and port for the SOCKS5 i
bought ) or give some other instructions.

 * Use something like `ssh -D 1081`. See `DynamicFoward` in `ssh_config(5)`.                                        * Use `iptables` to allow connections to 1081 on localhost.
 * For websites, modify FoxyProxy settings to add a new proxy, before rules
   for Tor, that contains the addresses that needs to be reached, and
   which directs connections to 1081.
 * For other programs, draft a dedicated `tsocks.conf`. Use
   `TSOCKS_CONF_FILE=tsocks-specific.conf tsocks ssh one.example.org`.

`proxychains` is in Debian, the package is called by the same name. This means
it is straightforword to install it in Tails. There is no way in can be
preconfigured for every Tails users, so it's hard to see why it should be
included in the default package set.

</rawmaterial>

Other topics
------------

- XXX_NICK_XXX in Pidgin might be caused by a lack of RAM
-->