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     <h2>Torbutton FAQ</h2>
     <li><a href="<page torbutton/torbutton-faq>#nojavascript">When I toggle Tor, my sites that use javascript stop working. Why?</a></li>
     <li><a href="<page torbutton/torbutton-faq>#noreloads">I can't click on links or hit reload after I toggle Tor! Why?</a></li>
     <li><a href="<page torbutton/torbutton-faq>#noflash">I can't view videos on YouTube and other flash-based sites. Why?</a></li>
     <li><a href="<page torbutton/torbutton-faq>#oldtorbutton">Torbutton sure seems to do a lot of things, some of which I find annoying. Can't I just use the old version?</a></li>
     <li><a href="<page torbutton/torbutton-faq>#weirdstate">My browser is in some weird state where nothing works right!</a></li>
     <li><a href="<page torbutton/torbutton-faq>#noautocomplete">When I use Tor, Firefox is no longer filling in logins/search boxes for me. Why?</a></li>
     <li><a href="<page torbutton/torbutton-faq>#thunderbird">What about Thunderbird support? I see a page, but it is the wrong version?</a></li>
     <li><a href="<page torbutton/torbutton-faq>#extensionconflicts">Which Firefox extensions should I avoid using?</a></li>
     <li><a href="<page torbutton/torbutton-faq>#recommendedextensions">Which Firefox extensions do you recommend?</a></li>
     <li><a href="<page torbutton/torbutton-faq>#securityissues">Are there any other issues I should be concerned about?</a></li>
     <a id="nojavascript"></a>
     <strong><a class="anchor" href="#nojavascript">When I toggle Tor, my sites that use javascript stop working. Why?</a></strong>
     Javascript can do things like wait until you have disabled Tor before trying
     to contact its source site, thus revealing your IP address. As such, Torbutton
     must disable Javascript, Meta-Refresh tags, and certain CSS behavior when Tor
     state changes from the state that was used to load a given page. These features
     are re-enabled when Torbutton goes back into the state that was used to load
     the page, but in some cases (particularly with Javascript and CSS) it is
     sometimes not possible to fully recover from the resulting errors, and the
     page is broken. Unfortunately, the only thing you can do (and still remain
     safe from having your IP address leak) is to reload the page when you toggle
     Tor, or just ensure you do all your work in a page before switching tor state.
     <a id="noreloads"></a>
     <strong><a class="anchor" href="#noreloads">I can't click on links or hit reload after I toggle Tor! Why?</a></strong>
     Due to <a href="">Firefox
     Bug 409737</a>, pages can still open popups and perform Javascript redirects
     and history access after Tor has been toggled. These popups and redirects can
     be blocked, but unfortunately they are indistinguishable from normal user
     interactions with the page (such as clicking on links, opening them in new
     tabs/windows, or using the history buttons), and so those are blocked as a
     side effect. Once that Firefox bug is fixed, this degree of isolation will
     become optional (for people who do not want to accidentally click on links and
     give away information via referrers). A workaround is to right click on the
     link, and open it in a new tab or window. The tab or window won't load
     automatically, but you can hit enter in the URL bar, and it will begin
     loading. Hitting enter in the URL bar will also reload the page without
     clicking the reload button.
     <a id="noflash"></a>
     <strong><a class="anchor" href="#noflash">I can't view videos on YouTube and
     other Flash-based sites. Why?</a></strong>
     YouTube and similar sites require third party browser plugins such as Flash.
     Plugins operate independently from Firefox and can perform
     activity on your computer that ruins your anonymity. This includes
     but is not limited to: <a href="">completely disregarding
     proxy settings</a>, querying your <a
     IP address</a>, and <a
     href="">storing their own
     cookies</a>. It is possible to use a LiveCD solution such as
     or <a href="">The Amnesic Incognito Live System</a> that creates a
     secure, transparent proxy to protect you from proxy bypass, however issues
     with local IP address discovery and Flash cookies still remain.  </p>
     If you are not concerned about being tracked by these sites (and sites that
     try to unmask you by pretending to be them), and are unconcerned about your
     local censors potentially noticing you visit them, you can enable plugins by
     going into the Torbutton Preferences-&gt;Security Settings-&gt;Dynamic Content
     tab and unchecking "Disable plugins during Tor usage" box. If you do this
     without The Amnesic Incognito Live System or appropriate firewall
     rules, we strongly suggest you at least use <a
     href="">NoScript</a> to <a
     href="">block plugins</a>. You do
     not need to use the NoScript per-domain permissions if you check the <b>Apply
     these restrictions to trusted sites too</b> option under the NoScript Plugins
     preference tab. In fact, with this setting you can even have NoScript allow
     Javascript globally, but still block all plugins until you click on their
     placeholders in a page. We also recommend <a
     href="">Better Privacy</a>
     in this case to help you clear your Flash cookies.
     <p><em>The Tor Browser Bundle does not work with Flash or other plugins
     by design.  If you wish to run these plugins over Tor, you need to
     install Tor and configure your own instance of Firefox.</em></p>
     <a id="oldtorbutton"></a>
     <strong><a class="anchor" href="#oldtorbutton">Torbutton sure seems to do a lot of things, some of which I find
     annoying. Can't I just use the old version?</a></strong>
     <b>No.</b> Use of the old version, or any other vanilla proxy changer
     (including FoxyProxy -- see below) without Torbutton is actively discouraged.
     Seriously. Using a vanilla proxy switcher by itself is so insecure that you are
     not only just wasting your time, you are also actually endangering yourself.
     <b>Simply do not use Tor</b> and you will have the same (and in some cases,
     better) security.  For more information on the types of attacks you are exposed
     to with a "homegrown" solution, please see <a
     href="design/index.html.en#adversary">The Torbutton
     Adversary Model</a>, in particular the <a
     Capabilities - Attacks</a> subsection. If there are any specific Torbutton
     behaviors that you do not like, please file a bug on <a
     bug tracker.</a> Most of Torbutton's security features can also be disabled via
     its preferences, if you think you have your own protection for those specific
     <a id="weirdstate"></a>
     <strong><a class="anchor" href="#weirdstate">My browser is in some weird state where nothing works right!</a></strong>
     Try to disable Tor by clicking on the button, and then open a new window. If
     that doesn't fix the issue, go to the preferences page and hit 'Restore
     Defaults'. This should reset the extension and Firefox to a known good
     configuration.  If you can manage to reproduce whatever issue gets your
     Firefox wedged, please file details at <a
     href="">the bug tracker</a>.
     <a id="noautocomplete"></a>
     <strong><a class="anchor" href="#noautocomplete">When I use Tor, Firefox is no longer filling in logins/search boxes
     for me. Why?</a></strong>
     Currently, this is tied to the "<b>Block history writes during Tor</b>"
     setting. If you have enabled that setting, all formfill functionality (both
     saving and reading) is disabled. If this bothers you, you can uncheck that
     option, but both history and forms will be saved. To prevent history
     disclosure attacks via Non-Tor usage, it is recommended you disable Non-Tor
     history reads if you allow history writing during Tor.
     <a id="thunderbird"></a>
     <strong><a class="anchor" href="#thunderbird">What about Thunderbird support? I see a page, but it is the wrong
     Torbutton used to support basic proxy switching on Thunderbird back in the 1.0
     days, but that support has been removed because it has not been analyzed for
     security. My developer tools page on clearly lists Firefox
     support only, so I don't know why they didn't delete that Thunderbird listing.
     I am not a Thunderbird user and unfortunately, I don't have time to analyze
     the security issues involved with toggling proxy settings in that app. It
     likely suffers from similar (but not identical) state and proxy leak issues
     with html mail, embedded images, javascript, plugins and automatic network
     access. My recommendation is to create a completely separate Thunderbird
     profile for your Tor accounts and use that instead of trying to toggle proxy
     settings. But if you really like to roll fast and loose with your IP, you
     could try another proxy switcher like ProxyButton, SwitchProxy or FoxyProxy
     (if any of those happen to support thunderbird).
     <a id="extensionconflicts"></a>
     <strong><a class="anchor" href="#extensionconflicts">Which Firefox extensions should I avoid using?</a></strong>
     This is a tough one. There are thousands of Firefox extensions: making a
     complete list of ones that are bad for anonymity is near impossible. However,
     here are a few examples that should get you started as to what sorts of
     behavior are dangerous.
      <li>StumbleUpon, et al
      These extensions will send all sorts of information about the websites you
      visit to the stumbleupon servers, and correlate this information with a
      unique identifier. This is obviously terrible for your anonymity.
      More generally, any sort of extension that requires registration, or even
      extensions that provide information about websites you visit should be
     While FoxyProxy is a nice idea in theory, in practice it is impossible to
     configure securely for Tor usage without Torbutton. Like all vanilla third
     party proxy plugins, the main risks are <a
     href="">plugin leakage</a>
     and <a href="">history
     disclosure</a>, followed closely by cookie theft by exit nodes and tracking by
     adservers (see the <a href="design/index.html.en#adversary">Torbutton Adversary
     Model</a> for more information). However, with Torbutton installed in tandem
     and always enabled, it is possible to configure FoxyProxy securely (though it
     is tricky). Since FoxyProxy's 'Patterns' mode only applies to specific urls,
     and not to an entire tab, setting FoxyProxy to only send specific sites
     through Tor will still allow adservers (whose hosts don't match your filters) to learn your real IP. Worse, when
     sites use offsite logging services such as Google Analytics, you will
     still end up in their logs with your real IP. Malicious exit nodes can also
     cooperate with sites to inject images into pages that bypass your filters.
     Setting FoxyProxy to only send certain URLs via Non-Tor is much more secure in
     this regard, but be very careful with the filters you allow. For example,
     something as simple as allowing *google* to go via Non-Tor will still cause you to end up
     in all the logs of all websites that use Google Analytics!  See
     <a href="">this question</a> on
     the FoxyProxy FAQ for more information.
     <a id="recommendedextensions"></a>
     <strong><a class="anchor" href="#recommendedextensions">Which Firefox extensions do you recommend?</a></strong>
      <li><a href="">RefControl</a>
     Mentioned above, this extension allows more fine-grained referrer spoofing
     than Torbutton currently provides. It should break less sites than Torbutton's
     referrer spoofing option.</p></li>
      <li><a href="">SafeCache</a>
     If you use Tor excessively, and rarely disable it, you probably want to
     install this extension to minimize the ability of sites to store long term
     identifiers in your cache. This extension applies same origin policy to the
     cache, so that elements are retrieved from the cache only if they are fetched
     from a document in the same origin domain as the cached element.
      <li><a href="">Better
     Better Privacy is an excellent extension that protects you from cookies used
     by Flash applications, which often persist forever and are not clearable via
     normal Firefox "Private Data" clearing. Flash and all other plugins are
     disabled by Torbutton by default, but if you are interested in privacy, you
     may want this extension to allow you to inspect and automatically clear your
     Flash cookies for your Non-Tor usage.
      <li><a href="">AdBlock Plus</a>
     AdBlock Plus is an excellent addon for removing annoying, privacy-invading,
     and <a
     advertisements from the web. It provides
     <a href="">subscriptions</a> that are
     continually updated to catch the latest efforts of ad networks to circumvent
     these filters. I recommend the EasyPrivacy+EasyList combination filter
     subscription in the Miscellaneous section of the subscriptions page.
     <li><a href="">Cookie Culler</a>
     Cookie Culler is a handy extension to give quick access to the cookie manager
     in Firefox. It also provides the ability to protect certain cookies from
     deletion, but unfortunately, this behavior does not integrate well with Torbutton. Kory Kirk is working on addressing this for this Google Summer of Code project for 2009.
      <li><a href="">NoScript</a>
      Torbutton currently mitigates all known anonymity issues with Javascript.
      However, if you are concerned about Javascript exploits against your browser
      or against websites you are logged in to, you may want to use NoScript. It
      provides the ability to allow Javascript only for particular websites
      and also provides mechanisms to force HTTPS urls for sites with
     <a href="">insecure
      It can be difficult to configure such that the most sites will work
      properly though. In particular, you want to make sure you do not remove
      the Javascript whitelist for, as extensions are downloaded via http and verified by
      javascript from the https page.
      <li><a href="">Request
     Request Policy is similar to NoScript in that it requires that you configure
     which sites are allowed to load content from other domains. It can be very
     difficult for novice users to configure properly, but it does provide a good
     deal of protection against ads, injected content, and cross-site request
     forgery attacks.
     <a id="securityissues"></a>
     <strong><a class="anchor" href="#securityissues">Are there any other issues I should be concerned about?</a></strong>
     There are a few known security issues with Torbutton (all of which are due to
     <a href="design/index.html.en#FirefoxBugs">unfixed
     Firefox security bugs</a>). The most important for anonymity is that it is
     possible to unmask the javascript hooks that wrap the Date object to conceal
     your timezone in Firefox 2, and the timezone masking code does not work at all
     on Firefox 3. We are working with the Firefox team to fix one of <a
     href="">Bug 399274</a> or
     <a href="">Bug 419598</a>
     to address this. In the meantime, it is possible to set the <b>TZ</b>
     environment variable to <b>UTC</b> to cause the browser to use UTC as your
     timezone. Under Linux, you can add an <b>export TZ=UTC</b> to the
     /usr/bin/firefox script, or edit your system bashrc to do the same. Under
     Windows, you can set either a <a
     href="">User or System Environment
     Variable</a> for TZ via My Computer's properties. In MacOS, the situation is
     lot more complicated</a>, unfortunately.
     In addition, RSS readers such as Firefox Livemarks can perform
     periodic fetches. Due to <a
     href="">Firefox Bug
     436250</a>, there is no way to disable Livemark fetches during Tor. This can
     be a problem if you have a lot of custom Livemark urls that can give away
     information about your identity.
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