Installing add-ons in the browser<span class="application">Tor Browser</span> might break the security built in Tails.

Installing add-ons in <span class="application">Tor Browser</span> might break the security built in Tails.

As explained in our documentation about
[[the fingerprinting|doc/about/ of *Tor Browser* in Tails|doc/anonymous_internet/Tor_Browser#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
<span class="application">Tor Browser</span> (either in Tails or on other operating systems).

As explained in our documentation about
[[the fingerprint of *Tor Browser* in Tails|doc/anonymous_internet/Tor_Browser#fingerprint]], Tails provides anonymity by
making it difficult to distinguish a particular user amongst all the users of
<span class="application">Tor Browser</span> (either in Tails or on other operating systems).

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.users of <span class="application">Tor Browser</span>.

So, the information retrieved by such fingerprinting websites is not harmful for
anonymity in itself, as long as it is the same for all users of <span class="application">Tor Browser</span>.

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 Firefoxstring of <span class="application">Tor Browser</span> includes
<em>Windows NT</em> but this value preserves your anonymity even if
you run Windows NT. On the other hand, changing this value makes you distinguishable from
others Tor users and br users of <span class="application">Tor Browser</span> and, as a
consequence, weakens your anonymity.

For example, the user-agent string of <span class="application">Tor Browser</span> includes
<em>Windows NT</em> but this value preserves your anonymity even if
you run Windows NT. On the other hand, changing this value makes you distinguishable from
other users of <span class="application">Tor Browser</span> and, as a
consequence, weakens your anonymity.

This second synchronization is made by sending HTTPS queries through Tor to severals
websites and deducing a correct time from their answers. TheYou can see the
list of websites that could be queried in this process can be found in `Tails can connect to in *[[!tails_gitweb config/chroot_local-includes/etc/default/htpdate.pools desc="/etc/default/htpdate`.pools"]]*.

This second synchronization is made by sending HTTPS queries through Tor to several
websites and deducing a correct time from their answers. You can see the
list of websites that Tails can connect to in *[[!tails_gitweb config/chroot_local-includes/etc/default/htpdate.pools desc="/etc/default/htpdate.pools"]]*.

This is currently not possible easily using Tails.<h2 id="relay">Can I help the Tor network by running a relay or a bridge in Tails?</h2>

<h2 id="relay">Can I help the Tor network by running a relay or a bridge in Tails?</h2>

<p>If a software is not included in Tails, but is included in Debian, you can use
the [[aAdditional s
Software|doc/first_steps/persistenct_storage/configure#additional_software]] feature of
the pPersistent volumStorage to install it automatically at the beginning of each working session.every time you start Tails.</p>

<p>If a software is not included in Tails, but is included in Debian, you can use
the [[Additional
Software|doc/persistent_storage/configure#additional_software]] feature of
the Persistent Storage to install it automatically every time you start Tails.</p>