[privoxy.git] / doc / source / faq.sgml

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<!entity p-version "3.0.29">
<!entity p-status "stable">
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]>
<!--
 File        :  doc/source/faq.sgml

 Purpose     :  FAQ

 Copyright (C) 2001-2020 Privoxy Developers https://www.privoxy.org/
 See LICENSE.

 Based partially on the Internet Junkbuster FAQ originally written by and
 Copyright (C) 1997 Anonymous Coders and Junkbusters Corporation.
 http://www.junkbusters.com/

 <Qandaset defaultlabel='qanda'>
  <QandAEntry>
   <question>
    <para>
     How are you?
    </para>
   </question>
   <answer>
    <para>
     Fine.
    </para>
   </answer>
  </QandAEntry>
 </QandASet>

 ========================================================================
 NOTE: Please read developer-manual/documentation.html before touching
 this file!

 Please we keep the info in this file as version independent as possible
 so we only have to maintain one FAQ. Where significant changes are
 made to Privoxy configuration, please note the change in such a way that
 it makes sense to both users of older and newer versions.
 ========================================================================


-->


<article id="index" class="faq">
<artheader>
<title>Privoxy Frequently Asked Questions</title>

<pubdate>
 <subscript>
<!-- Completely the wrong markup, but very little is allowed  -->
<!-- in this part of an article. FIXME -->
 <link linkend="copyright">Copyright</link> &my-copy; 2001-2020 by
 <ulink url="https://www.privoxy.org/">Privoxy Developers</ulink>
 </subscript>
</pubdate>

<!--

Note: this should generate a separate page, and a live link to it.
But it doesn't for some mysterious reason. Please leave commented
unless it can be fixed proper. For the time being, the copyright
statement will be in copyright.smgl.

Hal.

<legalnotice id="legalnotice">
 <para>
  text goes here ........
 </para>
</legalnotice>

-->

<!--
<authorgroup>
 <author>
  <affiliation>
   <orgname>By: Privoxy Developers</orgname>
   </affiliation>
 </author>
</authorgroup>
-->
<abstract>
<![%dummy;[
<para>
 <comment>
  This is here to keep vim syntax file from breaking :/
  If I knew enough to fix it, I would.
  PLEASE DO NOT REMOVE! HB: hal@foobox.net
 </comment>
</para>
]]>
 <para>
 This FAQ gives quick answers to frequently asked questions about
 <ulink url="https://www.privoxy.org/">Privoxy</ulink>.
 It is not a substitute for the
 <ulink url="../user-manual/index.html"><citetitle>Privoxy User Manual</citetitle></ulink>.
 </para>

<!-- Include privoxy.sgml boilerplate: -->
 <para>What is Privoxy?</para> &p-intro;
<!-- end boilerplate -->

 <para>
  Please note that this document is a work in progress. This copy represents
  the state at the release of version &p-version;.
  You can find the latest version of the document at <ulink
  url="https://www.privoxy.org/faq/">https://www.privoxy.org/faq/</ulink>.
  Please see the <link linkend="contact">Contact section</link> if you want to
  contact the developers.
 </para>

</abstract>
</artheader>


<!--   ~~~~~       New section      ~~~~~     -->

<sect1 id="general"><title>General Information</title>
<sect2 renderas="sect3" id="who-uses"><title>Who should give &my-app; a try?</title>
 <para>
  Anyone who is interested in security, privacy, or in
  finer-grained control over their web and Internet experience.
 </para>
</sect2>

<sect2 renderas="sect3" id="bestchoice"><title>Is Privoxy the best choice for
me?</title>
 <para>
  &my-app; is certainly a good choice, especially for those who want more
  control and security. Those with the willingness to read the documentation
  and the ability to fine-tune their installation will benefit the most.
 </para>
 <para>
  One of <application>Privoxy's</application>
  strengths is that it is highly configurable giving you the ability to
  completely personalize your installation. Being familiar with, or at least
  having an interest in learning about <ulink
  url="http://en.wikipedia.org/wiki/Http">HTTP</ulink> and other networking
  protocols, <ulink url="http://en.wikipedia.org/wiki/Html">HTML</ulink>, and
  <ulink url="http://en.wikipedia.org/wiki/Regular_expressions"><quote>Regular
  Expressions</quote></ulink>
  will be a big plus and will help you get the most out of &my-app;.
  A new installation just includes a very basic configuration. The user
  should take this as a starting point only, and enhance it as he or she
  sees fit. In fact, the user is encouraged, and expected to, fine-tune the
  configuration.
 </para>
 <para>
  Much of <application>Privoxy's</application> configuration can be done
  with a <ulink url="http://en.wikipedia.org/wiki/Web_browser">Web browser</ulink>.
  But there are areas where configuration is done using a
  <ulink url="http://en.wikipedia.org/wiki/Text_editors">text editor</ulink>
  to edit configuration files. Also note that the web-based action editor
  doesn't use authentication and should only be enabled in environments
  where all clients with access to &my-app; listening port can be trusted.
  </para>
</sect2>

<sect2 renderas="sect3" id="proxymoron"><title>What is a <quote>proxy</quote>? How does
Privoxy work? </title>
 <para>
  A <ulink url="http://en.wikipedia.org/wiki/Proxy_server">web proxy</ulink>
  is a service, based on a software such as &my-app;, that clients
  (i.e. browsers) can use instead of connecting to web servers directly.
  The clients then ask the proxy to request objects (web pages, images, movies etc)
  on their behalf and to forward the data to the clients.
  It is a <quote>go-between</quote>. For details, see
  <ulink url="http://en.wikipedia.org/wiki/Proxy_server">Wikipedia's proxy definition</ulink>.
 </para>
 <para>
  There are many reasons to use web proxies, such as security (firewalling),
  efficiency (caching) and others, and there are any number of proxies
  to accommodate those needs.
 </para>
 <para>
  &my-app; is a proxy that is primarily focused on
  privacy enhancement, ad and junk elimination and freeing the user from
  restrictions placed on his activities. Sitting between your browser(s) and the Internet,
  it is in a perfect position to filter outbound personal information that your
  browser is leaking, as well as inbound junk. It uses a variety of techniques to do
  this, all of which are under your complete control via the various configuration
  files and options. Being a proxy also makes it easier to share
  configurations among multiple browsers and/or users.
 </para>
</sect2>

<sect2 renderas="sect3" id="otherstuff">
<title>Does Privoxy do anything more than ad blocking?</title>
 <para>
  Yes, ad blocking is but one possible use. There are many, many ways &my-app;
  can be used to sanitize and customize web browsing.
</para>
</sect2>

<sect2 renderas="sect3" id="newjb"><title>What is this new version of
<quote><citetitle>Junkbuster</citetitle></quote>?</title>

<!-- Include history.sgml -->
 &history;
<!-- end -->

</sect2>


<sect2 renderas="sect3" id="whyprivoxy">
<title>Why <quote>Privoxy</quote>? Why change the name from
Junkbuster at all?</title>
<para>
 Though outdated, Junkbusters Corporation continued to offer their original
 version of the <application>Internet Junkbuster</application> for a while,
 so publishing our <application> Junkbuster</application>-derived software
 under the same name would have led to confusion.
</para>
<para>
 There were also potential legal reasons not to use the
 <application>Junkbuster</application> name, as it was (and maybe still is)
 a registered trademark of Junkbusters Corporation.
 There were, however, no objections from Junkbusters Corporation to the
 <application>Privoxy</application> project itself, and they, in fact,
 shared our ideals and goals.
</para>
<para>
 The Privoxy developers also believed that there were so many improvements
 over the original code, that it was time to make a clean break from the past
 and make a name in their own right.
</para>
<para>
 <application>Privoxy</application> is the
 <quote><emphasis>Privacy Enhancing Proxy</emphasis></quote>. Also, its content
 modification and junk suppression gives <emphasis>you</emphasis>, the user, more
 control, more freedom, and allows you to browse your personal and
 <quote><emphasis>private</emphasis> edition</quote> of the web.
</para>
</sect2>

<sect2 renderas="sect3" id="differs"><title>How does Privoxy differ
from the old Junkbuster?</title>
<para>
 <application>Privoxy</application> picks up where
 <application>Junkbuster</application> left off.
 <application>Privoxy</application> still blocks ads and banners,
 still manages <ulink
 url="http://en.wikipedia.org/wiki/Browser_cookie">cookies</ulink>, and still
 helps protect your privacy. But, most of these features have been enhanced,
 and many new ones have been added, all in the same vein.
 </para>
<para>
 <application>Privoxy</application>'s new features include:
</para>

<!-- Include newfeatures.sgml: -->
 &newfeatures;
<!-- end include -->

</sect2>

<sect2 renderas="sect3" id="whatsanad">
<title>How does Privoxy know what is an ad, and what is not?</title>
<para>
 <application>Privoxy</application>'s approach to blocking ads is twofold:
</para>
<para>
 First, there are certain patterns in the <emphasis>locations</emphasis> (URLs)
 of banner images. This applies to both the path (you wouldn't guess how many
 web sites serve their banners from a directory called <quote>banners</quote>!)
 and the host (blocking the big banner hosting services like doublecklick.net
 already helps a lot). <application>Privoxy</application> takes advantage of this
 fact by using <ulink url="../user-manual/actions-file.html#AF-PATTERNS">URL
 patterns</ulink> to sort out and block the requests for things that sound
 like they would be ads or banners.
</para>
<para>
 Second, banners tend to come in certain <emphasis>sizes</emphasis>. But you
 can't tell the size of an image by its URL without downloading it, and if you
 do, it's too late to save bandwidth. Therefore, <application>Privoxy</application>
 also inspects the HTML sources of web pages while they are loaded, and replaces
 references to images with standard banner sizes by dummy references, so that
 your browser doesn't request them anymore in the first place.
</para>
<para>
 Both of this involves a certain amount of guesswork and is, of course, freely
 and readily configurable.
</para>
</sect2>

<sect2 renderas="sect3" id="mistakes">
<title>Can Privoxy make mistakes?
This does not sound very scientific.</title>
<para>
 Actually, it's a black art ;-) And yes, it is always possible to have a broad
 rule accidentally block or change something by mistake. You will almost surely
 run into such situations at some point. It is tricky writing rules to
 cover every conceivable possibility, and not occasionally get false positives.
</para>

<para>
 But this should not be a big concern since the
 <application>Privoxy</application> configuration is very flexible, and
 includes tools to help identify these types of situations so they can be
 addressed as needed, allowing you to customize your installation.
 (<link linkend="badsite">See the Troubleshooting section below</link>.)
</para>

</sect2>

<sect2 renderas="sect3" id="configornot">
<title>Will I have to configure Privoxy
 before I can use it?</title>
<para>
 That depends on your expectations.
 The default installation should give you a good starting
 point, and block <emphasis>most</emphasis> ads and unwanted content,
 but many of the more advanced features are off by default, and require
 you to activate them.
</para>
<para>
 You do have to set up your browser to use
 <application>Privoxy</application> (see the <link
 linkend="firststep">Installation section below</link>).
</para>
<para>
 And you will certainly run into situations where there are false positives,
 or ads not being blocked that you may not want to see. In these cases, you
 would certainly benefit by customizing <application>Privoxy's</application>
 configuration to more closely match your individual situation. And we
 encourage you to do this. This is where the real power of
 <application>Privoxy</application> lies!
</para>

</sect2>

<sect2 renderas="sect3" id="lan">
<title>Can Privoxy run as a server on a network?</title>
 <para>
  Yes, &my-app; runs as a server already, and can easily be configured to
  <quote>serve</quote> more than one client. See <link linkend="lanconfig">
  How can I set up Privoxy to act as a proxy for my LAN</link> below.
</para>
</sect2>

<sect2 renderas="sect3" id="browsers2"><title>My browser does the same things as
Privoxy. Why should I use Privoxy at all?</title>
 <para>
  Modern browsers do indeed have <emphasis>some</emphasis> of the same
  functionality as <application>Privoxy</application>. Maybe this is
  adequate for you. But <application>Privoxy</application> is very
  versatile and powerful, and can probably do a number of things
  your browser just can't.
 </para>
 <para>
  In addition, a proxy is good choice if you use multiple browsers, or
  have a LAN with multiple computers since &my-app; can run as a server
  application. This way all the configuration is in one place, and you don't
  have to maintain a similar configuration for possibly many browsers or
  users.
 </para>
 <para>
  Note, however, that it's recommended to leverage both your browser's
  and <application>Privoxy's</application> privacy enhancing features
  at the same time. While your browser probably lacks some features
  &my-app; offers, it should also be able to do some things more
  reliably, for example restricting and suppressing JavaScript.
 </para>
</sect2>

<sect2 renderas="sect3" id="whytrust"><title>Why should I trust Privoxy?</title>
 <para>
  The most important reason is because you have access to
  <emphasis>everything</emphasis>, and you can control everything. You can
  check every line of every configuration file yourself. You can check every
  last bit of source code should you desire. And even if you can't read code,
  there should be some comfort in knowing that <!-- thousands of -->other people can,
  and do read it. You can build the software from scratch, if you want,
  so that you know the executable is clean, and that it is
  <emphasis>yours</emphasis>. In fact, we encourage this level of scrutiny. It
  is one reason we use &my-app; ourselves.
 </para>
</sect2>

<sect2 renderas="sect3" id="license"><title>Is there is a license or fee? What about a
warranty? Registration?</title>
 <para>
  <application>Privoxy</application> is free software and licensed under the <ulink
  url="https://www.gnu.org/licenses/old-licenses/gpl-2.0.html">GNU General Public License (GPL) version 2</ulink>.
  It is free to use, copy, modify or distribute as you wish under the terms of this
  license.  Please see the <link linkend="copyright">Copyright</link> section for more
  information on the license and copyright. Or the <filename>LICENSE</filename> file
  that should be included.
 </para>
 <para>
  There is <emphasis>no warranty</emphasis> of any kind, expressed, implied or otherwise.
  That is something that would cost real money ;-) There is no registration either.
 </para>

</sect2>

<sect2 renderas="sect3" id="spyware">
<title>Can Privoxy remove spyware? Adware? Viruses?</title>
<para>
 No, at least not reliably enough to trust it. &my-app; is not designed to be
 a malware removal tool and the default configuration doesn't even try to
 filter out any malware.
</para>
<para>
 &my-app; could help prevent contact from (known) sites that use such
 tactics with appropriate configuration rules, and thus could conceivably
 prevent contamination from such sites. However, keeping such a configuration
 up to date would require a lot of time and effort that would be better spend
 on keeping your software itself up to date so it doesn't have known
 vulnerabilities.
</para>
</sect2>


<sect2 renderas="sect3" id="otherads">
<title>Can I use Privoxy with other ad-blocking software?</title>
<para>
 &my-app; should work fine with other proxies and other software in general.
</para>
<para>
 But it is probably not necessary to use &my-app; in conjunction with other
 ad-blocking products, and this could conceivably cause undesirable results.
 It might be better to choose one software or the other and work a little to
 tweak its configuration to your liking.
</para>
<para>
 Note that this is an advice specific to ad blocking.
</para>
</sect2>

<sect2 renderas="sect3" id="help-the-developers"><title>I would like to help you, what can I do?</title>

<sect3 renderas="sect4" id="participate"><title>Would you like to participate?</title>
<para>
   Well, we <emphasis>always</emphasis> need help. There is something for
   everybody who wants to help us. We welcome new developers, packagers,
   testers, documentation writers or really anyone with a desire to help in
   any way. You <emphasis>DO NOT</emphasis> need to be a
   <quote>programmer</quote>. There are many other tasks available. In fact,
   the programmers often can't spend as much time programming because of some
   of the other, more mundane things that need to be done, like checking the
   Tracker feedback sections or responding to user questions on the mailing
   lists.
 </para>
 <para>
  So first thing, subscribe to the <ulink
   url="https://lists.privoxy.org/mailman/listinfo/privoxy-users">Privoxy Users</ulink>
  or the <ulink url="https://lists.privoxy.org/mailman/listinfo/privoxy-devel">Privoxy
  Developers</ulink> mailing list, join the discussion, help out other users, provide general
  feedback or report problems you noticed.
 </para>
 <para>
  If you intend to help out with the trackers, you also might want to <ulink
   url="https://sourceforge.net/user/registration">get an account on SourceForge.net</ulink>
   so we don't confuse you with the other name-less users.
 </para>
 <para>
   We also have a <ulink
   url="../developer-manual/index.html">Developer's Manual</ulink>.
   While it is partly out of date, it's still worth reading.
</para>
<para>
   Our <ulink url="https://www.privoxy.org/gitweb/?p=privoxy.git;a=blob_plain;f=TODO;hb=HEAD">TODO list</ulink>
   may be of interest to you as well.
   Please let us know if you want to work on one of the items listed.
</para>
</sect3>

<sect3 renderas="sect4" id="donate"><title>Would you like to donate?</title>
<para>
 Donations are welcome. Our
 <ulink url="https://www.privoxy.org/gitweb/?p=privoxy.git;a=blob_plain;f=TODO;hb=HEAD">TODO list</ulink>
 is rather long and being able to pay one (or more) developers to work on Privoxy
 would make a huge difference, even if it was only for a couple of weeks. Donations may
 also be used for Privoxy-related travel expenses (for example to attend conferences),
 for hardware used for Privoxy development and for hosting expenses etc.
</para>

<para>
 <application>Privoxy</application> is an associated
 project of <ulink url="https://www.spi-inc.org/">Software
 in the Public Interest (SPI)</ulink>, which allows us to receive
 tax-deductible donations in the United States.
 You can <ulink url="https://www.spi-inc.org/projects/privoxy/">donate via Paypal</ulink>
 and <ulink url="https://co.clickandpledge.com/advanced/default.aspx?wid=34115">Click & Pledge</ulink>.
 For details, please have a look at
 <ulink url="https://www.spi-inc.org/donations">SPI's general donation page</ulink>.
</para>

<para>
 If you have any questions regarding donations please mail to either the
 public user mailing list or, if it's a private matter, to
 <ulink url="mailto:fk@fabiankeil.de">Fabian Keil</ulink> (Privoxy's SPI liaison)
 directly.
</para>
</sect3>
</sect2>
<sect2 id="sponsor"><title>How can I become a sponsor and get my logo or link on privoxy.org?</title>
<para>
 We are currently offering the following sponsor levels as an experiment:
</para>
<variablelist>
 <varlistentry>
  <term>Gold (12000 USD/year)</term>
  <listitem>
   <para>
    Logo or text link shown at the bottom of the
    <ulink url="https://www.privoxy.org/">Privoxy homepage</ulink>.
    Logo, link and self description on the
    <ulink url="https://www.privoxy.org/sponsors/">sponsor page</ulink>.
   </para>
  </listitem>
 </varlistentry>
 <varlistentry>
  <term>Silver (1200 USD/year)</term>
  <listitem>
   <para>
    Logo or text link shown at the bottom of the
    <ulink url="https://www.privoxy.org/">Privoxy homepage</ulink>.
    Logo, link and self description on the
    <ulink url="https://www.privoxy.org/sponsors/">sponsor page</ulink>.
   </para>
  </listitem>
 </varlistentry>
 <varlistentry>
  <term>Bronze (600 USD/year)</term>
  <listitem>
   <para>
    Logo and link on the <ulink url="https://www.privoxy.org/sponsors/">sponsor page</ulink>.
   </para>
  </listitem>
 </varlistentry>
</variablelist>
<para>
 The logo sizes depend on the sponsor level. Logos are served from
 our server, no requests are made to the sponsor website unless
 the links are being used.
</para>
<para>
 Link targets are without path (<quote>https://www.example.org/</quote>
 not <quote>https://www.example.org/seo/keyword/spam/</quote>).
</para>
<para>
 The details may change over time but changes will only affect new sponsors
 (or existing sponsors that explicitly agreed to the changes).
</para>
<para>
 If you want to become a sponsor, please contact
 <ulink url="mailto:fk@fabiankeil.de">Fabian Keil</ulink>
 and include the link target in the mail.
 New sponsors are only accepted if no developer objects.
</para>

</sect2>

</sect1>


<!--   ~~~~~       New section      ~~~~~     -->

<sect1  id="installation"><title>Installation</title>

<sect2 renderas="sect3" id="whichbrowsers">
<title>Which browsers are supported by Privoxy?</title>
<para>
 Any browser that can be configured to use a proxy, which
 should be virtually all browsers, including
 <application>Firefox</application>, <application>Internet
 Explorer</application>, <application>Opera</application>, and
 <application>Safari</application> among others.
 Direct browser support is not an absolute requirement since
 <application>Privoxy</application> runs as a separate application and talks
 to the browser in the standardized HTTP protocol, just like a web server
 does.
</para>
</sect2>

<sect2 renderas="sect3" id="whichos">
<title>Which operating systems are supported?</title>
<!--
Include supported.sgml here:
-->
&supported;
</sect2>

<sect2 renderas="sect3" id="email-client">
<title>Can I use Privoxy with my email client?</title>
<para>
 As long as there is some way to set a HTTP proxy for the client, then yes,
 any application can be used, whether it is strictly speaking a
 <quote>browser</quote> or not. Though this may not be the best approach for
 dealing with some of the common abuses of HTML in email. See <link
 linkend="outlook">How can I configure <application>Privoxy</application>
 with <application>Outlook</application>?</link> below for more on
 this.
</para>
<para>
 Be aware that HTML email presents a number of unique security and privacy
 related issues, that can require advanced skills to overcome. The developers
 recommend using email clients that can be configured to convert HTML to plain
 text for these reasons.
</para>
</sect2>

<!-- Nobody is going to still be doing this!
<sect2 renderas="sect3" id="newinstall"><title>Can I install
 Privoxy over Junkbuster?</title>
 <para>
   We recommend you un-install <application>Junkbuster</application>
   first to minimize conflicts and confusion. You may want to
   save your old configuration files for future reference. The configuration
   files and syntax have substantially changed, so you will need to manually
   port your old patterns. See the <ulink url="../user-manual/upgradersnote.html">note
   to upgraders</ulink> and <ulink url="../user-manual/installation.html">installation
   chapter</ulink> in the <ulink url="../user-manual/index.html">User Manual</ulink>
   for details.
 </para>
 <para>
  Note: Some installers may automatically un-install
  <application>Junkbuster</application>, if present!
 </para>

</sect2>
-->

<sect2 renderas="sect3" id="firststep">
<title>I just installed Privoxy. Is there anything
special I have to do now?</title>

<para>
 All browsers should be told to use <application>Privoxy</application>
 as a proxy by specifying the correct proxy address and port number
 in the appropriate configuration area for the browser. It's possible
 to combine &my-app; with a packet filter to intercept HTTP requests
 even if the client isn't explicitly configured to use &my-app;,
 but where possible, configuring the client is recommended. See
 <ulink url="../user-manual/startup.html">the User Manual for more
 details</ulink>. You should also flush your browser's memory and disk
 cache to get rid of any cached junk items, and remove any stored
 <ulink url="http://en.wikipedia.org/wiki/Browser_cookie">cookies</ulink>.
</para>

</sect2>

<sect2 renderas="sect3" id="localhost"><title>What is the proxy address of Privoxy?</title>
 <para>
  If you set up the <application>Privoxy</application> to run on
  the computer you browse from (rather than your ISP's server or some
  networked computer on a LAN), the proxy will be on <literal>127.0.0.1</literal>
  (sometimes referred to as <quote>localhost</quote>,
  which is the special name used by every computer on the Internet to refer
  to itself) and the port will be 8118 (unless you used the <ulink
  url="../user-manual/config.html#LISTEN-ADDRESS">listen-address</ulink>
  config option to tell <application>Privoxy</application> to run on
  a different port).
 </para>
 <para>
  When configuring your browser's proxy settings you typically enter
  the word <quote>localhost</quote> or the IP address <quote>127.0.0.1</quote>
  in the boxes next to <quote>HTTP</quote> and <quote>Secure</quote> (HTTPS) and
  then the number <quote>8118</quote> for <quote>port</quote>.
  This tells your browser to send all web requests to <application>Privoxy</application>
  instead of directly to the Internet.
 </para>
 <para>
  <application>Privoxy</application> can also be used to proxy for
  a Local Area Network. In this case, your would enter either the IP
  address of the LAN host where <application>Privoxy</application>
  is running, or the equivalent hostname, e.g. <literal>192.168.1.1</literal>.
  Port assignment would be same as above. Note that
  <application>Privoxy</application> doesn't listen on any LAN interfaces by
  default.
 </para>
 <para>
  <application>Privoxy</application> does not currently handle
  any other protocols such as FTP, SMTP, IM, IRC, ICQ, etc.
 </para>
</sect2>

<sect2 renderas="sect3" id="nothing">
<title>I just installed Privoxy, and nothing is happening.
All the ads are there. What's wrong?</title>

<para>
 Did you configure your browser to use <application>Privoxy</application>
 as a proxy? It does not sound like it. See above. You might also try flushing
 the browser's caches to force a full re-reading of pages. You can verify
 that <application>Privoxy</application> is running, and your browser
 is correctly configured by entering the special URL:
 <ulink url="http://p.p/">http://p.p/</ulink>.
 <!-- Use http://p.p/ instead of http://config.privoxy.org/ here because
      of potential redirect caching problem (see next Q). -->
 This should take you to a page titled <quote>This is Privoxy..</quote> with
 access to <application>Privoxy's</application> internal configuration.
 If you see this, then you are good to go. If you receive a page saying
 <quote>Privoxy is not running</quote>, then the browser is not set up to use
 your <application>Privoxy</application> installation.
 If you receive anything else (probably nothing at all), it could either
 be that the browser is not set up correctly, or that
 <application>Privoxy</application> is not running at all. Check the <ulink
 url="../user-manual/config.html#LOGFILE">log file</ulink>. For instructions
 on starting <application>Privoxy</application> and browser configuration,
 see the <ulink url="https://www.privoxy.org/user-manual/startup.html">chapter
 on starting <application>Privoxy</application></ulink> in the
 <ulink url="https://www.privoxy.org/user-manual/">User Manual</ulink>.
</para>

</sect2>

<sect2 renderas="sect3" id="notused">
<title>I get a <quote>Privoxy is not being used</quote> dummy page although
Privoxy is running and being used.</title>

<para>
 First, make sure that Privoxy is <emphasis>really</emphasis> running and
 being used by visiting <ulink url="http://p.p/">http://p.p/</ulink>. You
 should see the <application>Privoxy</application> main page. If not, see
 the <ulink url="https://www.privoxy.org/user-manual/startup.html">chapter
 on starting <application>Privoxy</application></ulink> in the
 <ulink url="https://www.privoxy.org/user-manual/">User Manual</ulink>.
</para>

<para>
 Now if <ulink url="http://p.p/">http://p.p/</ulink> works for you, but
 other parts of <application>Privoxy</application>'s web interface show
 the dummy page, your browser has cached a redirection it encountered before
 <application>Privoxy</application> was being used. You need to clear your
 browser's cache. Note that shift-reloading the dummy page won't help, since
 that'll only refresh the dummy page, not the redirection that lead you there.
</para>

<para>
 The procedure for clearing the cache varies from browser to browser. For
 example, <application>Mozilla/Netscape</application> users would click
 <guibutton>Edit</guibutton> --> <guibutton>Preferences</guibutton> -->
 <guibutton>Advanced</guibutton> --> <guibutton>Cache</guibutton> and
 then click both <quote><guibutton>Clear Memory Cache</guibutton></quote>
 and <quote><guibutton>Clear Disk Cache</guibutton></quote>.
 In some <application>Firefox</application> versions it's
 <guibutton>Tools</guibutton> --> <guibutton>Options</guibutton> -->
 <guibutton>Privacy</guibutton> --> <guibutton>Cache</guibutton> and
 then click <quote><guibutton>Clear Cache Now</guibutton></quote>.
 <!-- In my Firefox versions it's the Netscape way. fk 2007-11-19-->
</para>
</sect2>

</sect1>


<!--   ~~~~~       New section      ~~~~~     -->

<sect1 id="configuration"><title>Configuration</title>
<sect2 renderas="sect3" id="actionsfile">
<title>What exactly is an <quote>actions</quote> file?</title>

<para>
 &my-app; utilizes the concept of <quote>
 <ulink url="../user-manual/actions-file.html#ACTIONS">actions</ulink></quote>
 that are used to manipulate and control web page data.
 <ulink url="../user-manual/actions-file.html">Actions files</ulink>
 are where these <ulink url="../user-manual/actions-file.html#ACTIONS">actions</ulink>
 that <application>Privoxy</application> could take while processing a certain
 request, are configured. Typically, you would define a set of default actions
 that apply globally to all URLs, then add exceptions to these defaults where needed.
 There is a wide array of actions available that give the user a high degree
 of control and flexibility on how to process each and every web page.
</para>

<para>
 Actions can be defined on a <ulink
 url="../user-manual/actions-file.html#AF-PATTERNS">URL pattern</ulink> basis, i.e.
 for single URLs, whole web sites, groups or parts thereof etc. Actions can also be
 grouped together and then applied to requests matching one or more patterns.
 There are many possible actions that might apply to any given site. As an example,
 if you are blocking <ulink url="http://en.wikipedia.org/wiki/Browser_cookie">cookies</ulink>
 as one of your default actions, but need to accept cookies from a given site,
 you would need to define an exception for this site in one of your actions
 files, preferably in <filename>user.action</filename>.
</para>

</sect2>

<sect2 renderas="sect3" id="actionss">
<title>The <quote>actions</quote> concept confuses me. Please list
some of these <quote>actions</quote>.</title>
<para>
 For a comprehensive discussion of the actions concept, please refer
 to the <ulink url="../user-manual/actions-file.html">actions file
 chapter</ulink> in the <ulink url="../user-manual/index.html">User
 Manual</ulink>. It includes a <ulink
 url="../user-manual/actions-file.html#ACTIONS">list of all actions</ulink>
 and an <ulink url="../user-manual/actions-file.html#ACT-EXAMPLES">actions
 file tutorial</ulink> to get you started.
</para>
</sect2>


<sect2 renderas="sect3" id="actconfig">
<title>How are actions files configured? What is the easiest
way to do this?</title>

<para>
 Actions files are just text files in a special syntax and can be edited
 with a text editor. But probably the easiest way is to access
 <application>Privoxy</application>'s user interface with your web browser
 at <ulink url="http://config.privoxy.org/">http://config.privoxy.org/</ulink>
 (Shortcut: <ulink url="http://p.p/">http://p.p/</ulink>) and then select
 <quote><ulink url="http://config.privoxy.org/show-status">View &
 change the current configuration</ulink></quote> from the menu. Note
 that this feature must be explicitly enabled in the main config file
 (see <ulink
 url="../user-manual/config.html#ENABLE-EDIT-ACTIONS">enable-edit-actions</ulink>).
</para>
</sect2>


<sect2 renderas="sect3" id="actionfile-differences">
<title>There are several different <quote>actions</quote> files. What are
the differences?</title>
<para>
 Please have a look at the <ulink url="../user-manual/actions-file.html">the actions chapter</ulink>
 in the <ulink url="../user-manual/index.html">User Manual</ulink> for a detailed explanation.
</para>

</sect2>

<sect2 renderas="sect3" id="getupdates"><title>Where can I get updated Actions Files?</title>
 <para>
  Based on your feedback and the continuing development, updates of
  <filename>default.action</filename> are available from
  <ulink
  url="https://www.privoxy.org/gitweb/?p=privoxy.git;a=blob_plain;f=default.action.master;hb=HEAD">git</ulink>.
 </para>

 <para>
  If you wish to receive an email notification whenever we release updates of
  <application>Privoxy</application> or the actions file, <ulink
  url="https://lists.privoxy.org/mailman/listinfo/privoxy-announce">subscribe
  to our announce mailing list</ulink>, privoxy-announce@lists.privoxy.org.
 </para>

</sect2>

<sect2 renderas="sect3" id="newconfig"><title>Can I use my old config files?</title>
 <para>
  The syntax and purpose of configuration files has remained roughly the
  same throughout the 3.x series, but backwards compatibility is not guaranteed.
  Also each release contains updated, <quote>improved</quote> versions and it is
  therefore strongly recommended to install the newer configuration files
  and merge back your modifications.
 </para>
</sect2>

<sect2 renderas="sect3" id="difficult">
<title>Why is the configuration so complicated?</title>
 <para>
  <quote>Complicated</quote> is in the eye of the beholder.
 </para>
 <para>
  Privoxy is currently mainly written by and for people who are already
  familiar with the underlying concepts like regular expressions, HTTP and HTML,
  or are willing to become familiar with them to be able to get the most
  out of a powerful and flexible tool such as Privoxy.
 </para>
 <para>
  While everybody is expected to be able to get a Privoxy default installation
  up and running, fine-tuning requires a certain amount of background
  information and Privoxy's documentation mainly concentrates on the
  Privoxy-specific parts while only providing references to the rest.
 </para>
 <para>
  If you or anyone you know has the skills, time and energy to
  reduce the barrier of entry, please <link linkend="participate">get involved</link>.
 </para>
</sect2>

<sect2 renderas="sect3" id="yahoo"><title>How can I make my Yahoo/Hotmail/Gmail account work?</title>
 <para>
  The default configuration shouldn't impact the usability of any of these services.
  It may, however, make all <ulink
 url="http://en.wikipedia.org/wiki/Browser_cookie">cookies</ulink>
  temporary, so that your browser will forget your
  login credentials in between browser sessions. If you would like not to have to log
  in manually each time you access those websites, simply turn off all cookie handling
  for them in the <filename>user.action</filename> file. An example for yahoo might
  look like:
 </para>
  <screen># Allow all cookies for Yahoo login:
#
{ -<ulink url="../user-manual/actions-file.html#CRUNCH-INCOMING-COOKIES">crunch-incoming-cookies</ulink> -<ulink url="../user-manual/actions-file.html#CRUNCH-OUTGOING-COOKIES">crunch-outgoing-cookies</ulink> -<ulink url="../user-manual/actions-file.html#SESSION-COOKIES-ONLY">session-cookies-only</ulink> }
.login.yahoo.com</screen>
 <para>
  These kinds of sites are often quite complex and heavy with
  <ulink url="http://en.wikipedia.org/wiki/Javascript">Javascript</ulink> and
  thus <quote>fragile</quote>. So if <emphasis>still</emphasis> a problem,
  we have an <ulink
  url="../user-manual/actions-file.html#ALIASES">alias</ulink> just for such
  sticky situations:
 </para>
  <screen># Gmail is a _fragile_ site:
#
{ <literal>fragile</literal> }
 # Gmail is ...
 mail.google.com</screen>
 <para>
  Be sure to flush your browser's caches whenever making these kinds of
  changes, just to make sure the changes <quote>take</quote>.
 </para>
 <para>
  Make sure the domain, host and path are appropriate as well. Your browser can
  tell you where you are specifically and you should use that information for
  your configuration settings. Note that above it is not referenced as
  <literal>gmail.com</literal>, which is a valid domain name.
 </para>

</sect2>

<sect2 renderas="sect3" id="configfiles"> <title>What's the difference between the
<quote>Cautious</quote>, <quote>Medium</quote> and <quote>Advanced</quote> defaults?</title>
 <para>
  Configuring <application>Privoxy</application> is not entirely trivial. To
  help you get started, we provide you with three different default action
  <quote>profiles</quote> in the web based actions file editor at <ulink
  url="http://config.privoxy.org/show-status">http://config.privoxy.org/show-status</ulink>.
  See the <ulink url="../user-manual/actions-file.html"><citetitle>User
  Manual</citetitle></ulink> for a list of actions, and how the default
  profiles are set.
 </para>

<para>
 Where the defaults are likely to break some sites, exceptions for
 known popular <quote>problem</quote> sites are included, but in
 general, the more aggressive your default settings are, the more exceptions
 you will have to make later. New users are best to start off in
 <quote>Cautious</quote> setting. This is safest and will have the fewest
 problems. See the <ulink
 url="../user-manual/index.html"><citetitle>User Manual</citetitle></ulink>
 for a more detailed discussion.
</para>

<para>
 It should be noted that the <quote>Advanced</quote> profile (formerly known
 as the <quote>Adventuresome</quote> profile) is more
 aggressive, and will make use of some of
 <application>Privoxy's</application> advanced features. Use at your own risk!
</para>

</sect2>

<sect2 renderas="sect3" id="browseconfig"> <title>Why can I change the configuration
with a browser? Does that not raise security issues?</title>
 <para>
  It may seem strange that regular users can edit the config files with their
  browsers, although the whole <filename>/etc/privoxy</filename> hierarchy
  belongs to the user <quote>privoxy</quote>, with only 644 permissions.
 </para>
 <para>
  When you use the browser-based editor, <application>Privoxy</application>
  itself is writing to the config files.  Because
  <application>Privoxy</application> is running as the user <quote>privoxy</quote>,
  it can update its own config files.
 </para>
 <para>
  If you run <application>Privoxy</application> for multiple untrusted users (e.g. in
  a LAN) or aren't entirely in control of your own browser, you will probably want
  to make sure that the web-based editor and remote toggle features are
  <quote>off</quote> by setting <quote><literal><ulink
  url="../user-manual/config.html#ENABLE-EDIT-ACTIONS">enable-edit-actions</ulink>
  0</literal></quote> and <quote><literal><ulink
  url="../user-manual/config.html#ENABLE-REMOTE-TOGGLE">enable-remote-toggle</ulink>
  0</literal></quote> in the <ulink url="../user-manual/config.html">main configuration file</ulink>.
 </para>
 <para>
  As of &my-app; 3.0.7 these options are disabled by default.
 </para>
</sect2>


<sect2 renderas="sect3" id="filterfile">
<title>What is the <filename>default.filter</filename> file? What is a <quote>filter</quote>?</title>
<para>
 The <ulink url="../user-manual/filter-file.html"><filename>default.filter</filename></ulink>
 file is where <emphasis>filters</emphasis> as supplied by the developers are defined.
 Filters are a special subset of actions that can be used to modify or
 remove web page content or headers on the fly. Content filters can
 be applied to <emphasis>anything</emphasis> in the page source,
 header filters can be applied to either server or client headers.
 Regular expressions are used to accomplish this.
</para>
<para>
 There are a number of pre-defined filters to deal with common annoyances. The
 filters are only defined here, to invoke them, you need to use the
 <ulink
 url="../user-manual/actions-file.html#FILTER"><literal>filter</literal>
 action</ulink> in one of the actions files. Content filtering is automatically
 disabled for inappropriate MIME types, but if you know better than Privoxy
 what should or should not be filtered you can filter any content you like.
</para>
<para>
 Filters should
 <emphasis>not</emphasis> be confused with <ulink
 url="../user-manual/actions-file.html#BLOCK"><literal>blocks</literal></ulink>, which
 is a completely different action, and is more typically used to block ads and
 unwanted sites.
</para>

<para>
 If you are familiar with regular expressions, and HTML, you can look at
 the provided <filename>default.filter</filename> with a text editor and define
 your own filters.  This is potentially a very powerful feature, but
 requires some expertise in both regular expressions and HTML/HTTP.
 <![%p-newstuff;[ You should
 place any modifications to the default filters, or any new ones you create
 in a separate file, such as <filename>user.filter</filename>, so they won't
 be overwritten during upgrades.
 The ability to define multiple filter files
 in <filename>config</filename> is a new feature as of v. 3.0.5.]]>
</para>

<para>
 There is no GUI editor option for this part of the configuration,
 but you can disable/enable the various pre-defined filters of the included
 <filename>default.filter</filename> file with the <ulink
 url="http://config.privoxy.org/show-status">web-based actions file editor</ulink>.
 Note that the custom actions editor must be explicitly enabled in
 the main config file (see <ulink
 url="../user-manual/config.html#ENABLE-EDIT-ACTIONS">enable-edit-actions</ulink>).
</para>

<para>
 If you intend to develop your own filters, you might want to have a look at
 <ulink
 url="https://www.fabiankeil.de/sourcecode/pft/">Privoxy-Filter-Test</ulink>.
</para>

</sect2>

<sect2 renderas="sect3" id="lanconfig">
<title>How can I set up Privoxy to act as a proxy for my
 LAN?</title>
<para>
 By default, <application>Privoxy</application> only responds to requests
 from <literal>127.0.0.1</literal> (localhost). To have it act as a server for
 a network, this needs to be changed in the <ulink
 url="../user-manual/config.html">main configuration file</ulink>. Look for
 the <literal><ulink
 url="../user-manual/config.html#LISTEN-ADDRESS">listen-address</ulink></literal>
 option, which may be commented out with a <quote>#</quote> symbol. Make sure
 it is uncommented, and assign it the address of the LAN gateway interface,
 and port number to use. Assuming your LAN address is 192.168.1.1 and you
 wish to run <application>Privoxy</application> on port 8118, this line
 should look like:
</para>

 <screen>
  listen-address  192.168.1.1:8118</screen>

<para>
 Save the file, and restart <application>Privoxy</application>. Configure
 all browsers on the network then to use this address and port number.
</para>

<para>
 Alternately, you can have <application>Privoxy</application> listen on
 all available interfaces:
</para>

 <screen>
  listen-address    :8118</screen>

<para>
 And then use <application>Privoxy's</application>
 <ulink
 url="../user-manual/config.html#PERMIT-ACCESS">permit-access</ulink>
 feature to limit connections. A firewall in this situation is recommended
 as well.
</para>

<para>
 The above steps should be the same for any TCP network, regardless of
 operating system.
</para>

<para>
 If you run <application>Privoxy</application> on a LAN with untrusted users,
 we recommend that you double-check the <ulink
 url="../user-manual/config.html#ACCESS-CONTROL">access control and security</ulink>
 options!
</para>

</sect2>


<sect2 renderas="sect3" id="noseeum">
<title>Instead of ads, now I get a checkerboard pattern. I don't want to see anything.</title>
<para>
 The replacement for blocked images can be controlled with the <ulink
 url="../user-manual/actions-file.html#SET-IMAGE-BLOCKER"><literal>set-image-blocker</literal>
 action</ulink>. You have the choice of a checkerboard pattern, a transparent 1x1 GIF
 image (aka <quote>blank</quote>), or a redirect to a custom image of your choice.
 Note that this choice only has effect for images which are blocked as images, i.e.
 whose URLs match both a <literal><ulink
 url="../user-manual/actions-file.html#HANDLE-AS-IMAGE">handle-as-image</ulink></literal>
 <emphasis>and</emphasis> <literal><ulink
 url="../user-manual/actions-file.html#BLOCK">block</ulink></literal> action.
</para>
<para>
 If you want to see nothing, then change the <ulink
 url="../user-manual/actions-file.html#SET-IMAGE-BLOCKER"><literal>set-image-blocker</literal>
 action</ulink> to <quote>blank</quote>. This can be done by editing the
 <filename>user.action</filename> file, or through the <ulink
 url="http://config.privoxy.org/show-status">web-based actions file editor</ulink>.
</para>

</sect2>

<sect2 renderas="sect3" id="whyseeum">
<title>Why would anybody want to see a checkerboard pattern?</title>
<para>
 Remember that <link linkend="whatsanad">telling which image is an ad and which
 isn't</link>, is an educated guess. While we hope that the standard configuration
 is rather smart, it will make occasional mistakes. The checkerboard image is visually
 decent, and it shows you where images have been blocked, which can be very
 helpful in case some navigation aid or otherwise innocent image was
 erroneously blocked. It is recommended for new users so they can
 <quote>see</quote> what is happening. Some people might also enjoy seeing how
 many banners they <emphasis>don't</emphasis> have to see.
</para>

</sect2>

<sect2 renderas="sect3" id="blockedbytext">
<title>I see some images being replaced with text
instead of the checkerboard image. Why and how do I get rid of this?</title>
<para>
 This happens when the banners are not embedded in the HTML code of the
 page itself, but in separate HTML (sub)documents that are loaded into (i)frames
 or (i)layers, and these external HTML documents are blocked. Being non-images
 they get replaced by a substitute HTML page rather than a substitute image,
 which wouldn't work out technically, since the browser expects and accepts
 only HTML when it has requested an HTML document.
</para>
<para>
 The substitute page adapts to the available space and shows itself as a
 miniature two-liner if loaded into small frames, or full-blown with a
 large red "BLOCKED" banner if space allows.
</para>
<para>
 If you prefer the banners to be blocked by images, you must see to it that
 the HTML documents in which they are embedded are not blocked. Clicking
 the <quote>See why</quote> link offered in the substitute page will show
 you which rule blocked the page. After changing the rule and un-blocking
 the HTML documents, the browser will try to load the actual banner images
 and the usual image blocking will (hopefully!) kick in.
</para>
</sect2>


<sect2 renderas="sect3" id="srvany">
<title>Can Privoxy run as a service
on Win2K/NT/XP?</title>
<para>
 Yes. Full <application>Windows</application> service
 functionality was introduced in <application>Privoxy</application> 3.0.5.
 See <ulink url="../user-manual/installation.html#INSTALLATION-PACK-WIN">
 the <citetitle>User Manual</citetitle></ulink> for details on how to install and configure
 <application>Privoxy</application> as a service.
</para>
</sect2>


<sect2 renderas="sect3" id="otherproxy">
<title>How can I make Privoxy work with other proxies?</title>
<para>
 This can be done and is often useful to combine the benefits of
 <application>Privoxy</application> with those of a another proxy,
 for example to cache content.
 See the <ulink
 url="../user-manual/config.html#FORWARDING">forwarding chapter</ulink>
 in the <ulink url="../user-manual/index.html">User Manual</ulink> which
 describes how to do this. If you intend to use Privoxy with Tor,
 please also have a look at
 <link linkend="TOR">How do I use Privoxy together with Tor</link>.
</para>
</sect2>

<sect2 renderas="sect3" id="port-80">
<title>Can I just set Privoxy to use port 80
and thus avoid individual browser configuration?</title>

<para>
 No, its more complicated than that. This only works with special kinds
 of proxies known as <quote>intercepting</quote> proxies
 (<link linkend="INTERCEPTING">see below</link>).
</para>

</sect2>

<sect2 renderas="sect3" id="transparent">
<title>Can Privoxy run as a <quote>transparent
</quote> proxy?</title>
<para>
 The whole idea of Privoxy is to modify client requests
 and server responses in all sorts of ways and therefore
 it's not a transparent proxy as described in
 <ulink url="http://tools.ietf.org/html/rfc2616">RFC 2616</ulink>.
</para>
<para>
 However, some people say <quote>transparent proxy</quote> when they
 mean <quote>intercepting proxy</quote>. If you are one of them,
 please read the <link linkend="INTERCEPTING">next entry</link>.
</para>

</sect2>

<sect2 renderas="sect3" id="intercepting">
<title>Can Privoxy run as a <quote>intercepting</quote> proxy?</title>
<para>
 <application>Privoxy</application> can't intercept traffic itself,
  but it can handle requests that where intercepted and redirected
  with a packet filter (like <application>PF</application> or
  <application>iptables</application>), as long as the <literal>Host</literal>
  header is present.
  </para>
<para>
  As the <literal>Host</literal> header is required by HTTP/1.1 and as most
  web sites rely on it anyway, this limitation shouldn't be a problem.
</para>
<para>
  Please refer to your packet filter's documentation to learn how to
  intercept and redirect traffic into <application>Privoxy</application>.
  Afterward you just have to configure <application>Privoxy</application> to
  <ulink url="../user-manual/config.html#ACCEPT-INTERCEPTED-REQUESTS">accept
  intercepted requests</ulink>.
</para>

</sect2>

<sect2 renderas="sect3" id="outlook">
<title>How can I configure Privoxy for use with Outlook?</title>
<para>
 Versions of <application>Outlook</application> prior to Office 2007, use
 <application>Internet Explorer</application> components to both render HTML,
 and fetch any HTTP requests that may be embedded in an HTML email. So however
 you have <application>Privoxy</application> configured to work with IE, this
 configuration should automatically be shared, at least with older version of
 Internet Explorer.
</para>
<para>
 Starting with Office 2007, Microsoft is instead using the MS-Word rendering
 engine with Outlook. It is unknown whether this can be configured to use a
 proxy.
 <!-- FIXME HB 2009-02-15 -->
</para>
</sect2>

<sect2 renderas="sect3" id="outlook-more">
<title>How can I have separate rules just for HTML mail?</title>
<para>
 The short answer is, you can't. <application>Privoxy</application> has no way
 of knowing which particular application makes a request, so there is no way to
 distinguish between web pages and HTML mail.
 <application>Privoxy</application> just blindly proxies all requests. In the
 case of <application>Outlook Express</application> (see above), OE uses
 IE anyway, and there is no way for <application>Privoxy</application> to ever
 be able to distinguish between them (nor could any other proxy type application for
 that matter).
</para>
<para>
 For a good discussion of some of the issues involved (including privacy and
 security issues), see
 <ulink url="https://sourceforge.net/p/ijbswa/support-requests/107/"
  >https://sourceforge.net/p/ijbswa/support-requests/107/</ulink>.
</para>
</sect2>

<sect2 renderas="sect3" id="sneaky-cookies">
<title>I sometimes notice cookies sneaking through. How?</title>
<para>
 <ulink
 url="http://en.wikipedia.org/wiki/Browser_cookie">Cookies</ulink> can be
 set in several ways. The classic method is via the
 <literal>Set-Cookie</literal> HTTP header. This is straightforward, and an
 easy one to manipulate, such as the &my-app; concept of
 <ulink url="../user-manual/actions-file.html#SESSION-COOKIES-ONLY">session-cookies-only</ulink>.
 There is also the possibility of using
  <ulink url="http://en.wikipedia.org/wiki/Javascript">Javascript</ulink> to
 set cookies (&my-app; calls these <literal>content-cookies</literal>). This
 is trickier because the syntax can vary widely, and thus requires a certain
 amount of guesswork. It is not realistic to catch all of these short of
 disabling Javascript, which would break many sites. And lastly, if the
 cookies are embedded in a HTTPS/SSL secure session via Javascript, they are beyond
 <application>Privoxy's</application> reach unless you enable
 <ulink url="../user-manual/actions-file.html#HTTPS-INSPECTION">https-inspection</ulink>.
</para>
<para>
 All in all, &my-app; can help manage cookies in general, can help minimize
 the loss of privacy posed by cookies, but can't realistically stop all
 cookies.
</para>
</sect2>

<sect2 renderas="sect3" id="evil-cookies">
<title>Are all cookies bad? Why?</title>
<para>
 No, in fact there are many beneficial uses of
 <ulink
 url="http://en.wikipedia.org/wiki/Browser_cookie">cookies</ulink>. Cookies are just a
 method that browsers can use to store data between pages, or between browser
 sessions. Sometimes there is a good reason for this, and the user's life is a
 bit easier as a result. But there is a long history of some websites taking
 advantage of this layer of trust, and using the data they glean from you and
 your browsing habits for their own purposes, and maybe to your potential
 detriment. Such sites are using you and storing their data on your system.
 That is why the privacy conscious watch from whom those cookies come, and why
 they really <emphasis>need</emphasis> to be there.
</para>
<para>
  See the
   <ulink url="http://en.wikipedia.org/wiki/Browser_cookie">Wikipedia cookie
  definition</ulink> for more.
</para>
</sect2>

<sect2 renderas="sect3" id="allow-cookies">
<title>How can I allow permanent cookies for my trusted sites?</title>

<para>
  There are several actions that relate to cookies. The default behavior is to
  allow only <quote>session cookies</quote>, which means the cookies only last
  for the current browser session. This eliminates most kinds of abuse related
  to cookies. But there may be cases where you want cookies to last.
</para>
<para>
  To disable all cookie actions, so that cookies are allowed unrestricted,
  both in and out, for <literal>example.com</literal>:
</para>
 <screen>
 { -crunch-incoming-cookies -crunch-outgoing-cookies -session-cookies-only -filter{content-cookies} }
  .example.com</screen>
<para>
 Place the above in <filename>user.action</filename>. Note that some of these may
 be off by default anyway, so this might be redundant, but there is no harm
 being explicit in what you want to happen. <filename>user.action</filename>
 includes an alias for this situation, called
 <literal>allow-all-cookies</literal>.
</para>
</sect2>

<sect2 renderas="sect3" id="multiples">
<title>Can I have separate configurations for different users?</title>
<para>
 Each instance of <application>Privoxy</application> has its own
 configuration, including such attributes as the TCP port that it listens on.
 What you can do is run multiple instances of <application>Privoxy</application>, each with
 a unique
 <ulink url="../user-manual/config.html#LISTEN-ADDRESS">listen-address</ulink>
 configuration setting, and configuration path, and then
 each of these can have their own configurations. Think of it as per-port
 configuration.
</para>
<para>
 Simple enough for a few users, but for large installations, consider having
 groups of users that might share like configurations.
</para>
</sect2>

<sect2 renderas="sect3" id="whitelists">
<title>Can I set-up Privoxy as a whitelist of
<quote>good</quote> sites?</title>
<para>
 Sure. There are a couple of things you can do for simple white-listing.
 Here's one real easy one:
</para>
 <screen>
 ############################################################
 # Blacklist
 ############################################################
 { <ulink url="../user-manual/actions-file.html#BLOCK">+block</ulink> }
 / # Block *all* URLs

 ############################################################
 # Whitelist
 ############################################################
 { <ulink url="../user-manual/actions-file.html#BLOCK">-block</ulink> }
  kids.example.com
  toys.example.com
  games.example.com</screen>
<para>
 This allows access to only those three sites by first blocking all URLs, and
 then subsequently allowing three specific exceptions.
</para>
<para>
 Another approach is <application>Privoxy's</application>
 <literal>trustfile</literal> concept, which incorporates the notion of
 <quote>trusted referrers</quote>. See the <ulink
 url="../user-manual/config.html#TRUSTFILE">Trust documentation</ulink>
 for details.
</para>
<para>
 These are fairly simple approaches and are not completely foolproof. There
 are various other configuration options that should be disabled (described
 elsewhere here and in <ulink url="../user-manual/">the User Manual</ulink>)
 so that users can't modify their own configuration and easily circumvent the
 whitelist.
</para>
</sect2>

<sect2 renderas="sect3" id="no-adblock">
<title>How can I turn off ad-blocking?</title>
<para>
 Ad blocking is achieved through a complex application of various &my-app;
 <ulink url="../user-manual/actions-file.html">actions</ulink>. These
 actions are deployed against simple images, banners, flash animations,
 text pages, JavaScript, pop-ups and pop-unders, etc., so its not as simple as
 just turning one or two actions off. The various actions that make up
 &my-app; ad blocking are hard-coded into the default configuration files. It
 has been assumed that everyone using &my-app; is interested in this
 particular feature.
 </para>
 <para>
 If you want to do without this, there are several approaches you can take:
 You can manually undo the many block rules in
 <filename>default.action</filename>. Or even easier, just create your own
 <filename>default.action</filename> file from scratch without the many ad
 blocking rules, and corresponding exceptions. Or lastly, if you are not
 concerned about the additional blocks that are done for privacy reasons, you
 can very easily over-ride <emphasis>all</emphasis> blocking with the
 following very simple rule in your <filename>user.action</filename>:
 </para>
 <screen>
 # Unblock everybody, everywhere
 { <ulink url="../user-manual/actions-file.html#BLOCK">-block</ulink> }
 / # UN-Block *all* URLs</screen>
<para>
 Or even a more comprehensive reversing of various ad related actions:
</para>
 <screen>
 # Unblock everybody, everywhere, and turn off appropriate filtering, etc
 { <ulink url="../user-manual/actions-file.html#BLOCK">-block</ulink> \
  <ulink url="../user-manual/actions-file.html#FILTER-BANNERS-BY-SIZE">-filter{banners-by-size}</ulink> \
  <ulink url="../user-manual/actions-file.html#FILTER-BANNERS-BY-LINK">-filter{banners-by-link}</ulink> \
  <literal>allow-popups</literal> \
 }
 / # UN-Block *all* URLs and allow ads</screen>
<para>
 This last <quote>action</quote> in this compound statement,
 <literal>allow-popups</literal>, is an <ulink
 url="../user-manual/actions-file.html#ALIASES">alias</ulink> that disables
 various pop-up blocking features.
</para>
</sect2>

<sect2 renderas="sect3" id="templates">
<title>How can I have custom template pages, like the
<emphasis>BLOCKED</emphasis> page?</title>
<para>
 &my-app; <quote>templates</quote> are specialized text files utilized by
 &my-app; for various purposes and can easily be modified using any text
 editor. All the template pages are installed in a sub-directory appropriately
 named: <filename>templates</filename>.  Knowing something about HTML syntax
 will of course be helpful.
</para>
<para>
 Be forewarned that the default templates are subject to being overwritten
 during upgrades. You can, however, create completely new templates,
 place them in another directory and specify the alternate path in the main
 <filename>config</filename>. For details, have a look at the <ulink
 url="../user-manual/config.html#TEMPLDIR">templdir</ulink> option.
</para>
</sect2>

<sect2 renderas="sect3" id="blockall">
<title>How can I remove the <quote>Go There Anyway</quote> link from
the <emphasis>BLOCKED</emphasis> page?</title>
<para>
 There is more than one way to do it (although Perl is not involved).
</para>
<para>
 Editing the BLOCKED template page (see above) may dissuade some users, but
 this method is easily circumvented. Where you need this level of control, you
 might want to build &my-app; from source, and disable various features that are
 available as compile-time options. You should
 <command>configure</command> the sources as follows:
</para>
 <screen>
 ./configure  --disable-toggle  --disable-editor  --disable-force</screen>
<para>
 This will create an executable with hard-coded security features so that
 &my-app; does not allow easy bypassing of blocked sites, or changing the
 current configuration via any connected user's web browser.
</para>
<para>
 Finally, all of these features can also be toggled on/off via options in
 <application>Privoxy's</application> main  <ulink
 url="../user-manual/config.html#ACCESS-CONTROL">config</ulink> file which
 means you don't have to recompile anything.
</para>
</sect2>

</sect1>

<!--  ~  End section  ~  -->


<!--   ~~~~~       New section      ~~~~~     -->

<sect1 id="misc"><title>Miscellaneous</title>

<sect2 renderas="sect3" id="slowsme">
<title>How much does Privoxy slow my browsing down? This
has to add extra time to browsing.</title>
<para>
 How much of an impact depends on many things, including the CPU of the host
 system, how aggressive the configuration is, which specific actions are being triggered,
 the size of the page, the bandwidth of the connection, etc.
</para>
<para>
 Overall, it should not slow you down any in real terms, and may actually help
 speed things up since ads, banners and other junk are not typically being
 retrieved and displayed. The actual processing time required by
 <application>Privoxy</application> itself for each page, is relatively small
 in the overall scheme of things, and happens very quickly. This is typically
 more than offset by time saved not downloading and rendering ad images and
 other junk content (if ad blocking is being used).
</para>

<para>
 <quote>Filtering</quote> content via the <literal><ulink
 url="../user-manual/actions-file.html#FILTER">filter</ulink></literal> or
 <literal><ulink
 url="../user-manual/actions-file.html#DEANIMATE-GIFS">deanimate-gifs</ulink></literal>
 actions may cause a perceived slowdown, since the entire document
 needs to be buffered before displaying. And on very large documents,
 filtering may have some measurable impact. How much depends on the page size,
 the actual definition of the filter(s), etc. See below. Most other actions
 have little to no impact on speed.
</para>
<para>
 Also, when filtering is enabled but zlib support isn't available, compression
 is often disabled (see <ulink
 url="../user-manual/actions-file.html#PREVENT-COMPRESSION">prevent-compression</ulink>).
 This can have an impact on speed as well, although it's probably smaller than
 you might think. Again, the page size, etc. will determine how much of an impact.
</para>

</sect2>


<sect2 renderas="sect3" id="loadingtimes"><title>I notice considerable
delays in page requests. What's wrong?</title>
<para>
 If you use any <literal><ulink
 url="../user-manual/actions-file.html#FILTER">filter</ulink></literal> action,
 such as filtering banners by size, web-bugs etc, or the <literal><ulink
 url="../user-manual/actions-file.html#DEANIMATE-GIFS">deanimate-gifs</ulink></literal>
 action, the entire document must be loaded into memory in order for the filtering
 mechanism to work, and nothing is sent to the browser during this time.
</para>
<para>
 The loading time typically does not really change much in real numbers, but
 the feeling is different, because most browsers are able to start rendering
 incomplete content, giving the user a feeling of "it works". This effect is
 more noticeable on slower dialup connections. Extremely large documents
 may have some impact on the time to load the page where there is filtering
 being done. But overall, the difference should be very minimal. If there is a
 big impact, then probably some other situation is contributing (like
 anti-virus software).
 </para>
<para>
 Filtering is automatically disabled for inappropriate MIME types. But note
 that if the web server mis-reports the MIME type, then content that should
 not be filtered, could be. <application>Privoxy</application> only knows how
 to differentiate filterable content because of the MIME type as reported by
 the server, or because of some configuration setting that enables/disables
 filtering.
</para>
</sect2>

<sect2 renderas="sect3" id="configurl"><title>What are "http://config.privoxy.org/" and
"http://p.p/"?</title>
<para>
 <ulink url="http://config.privoxy.org/">http://config.privoxy.org/</ulink> is the
 address of <application>Privoxy</application>'s built-in user interface, and
 <ulink url="http://p.p/">http://p.p/</ulink> is a shortcut for it.
</para>
<para>
 Since <application>Privoxy</application> sits between your web browser and the Internet,
 it can simply intercept requests for these addresses and answer them with its built-in
 <quote>web server</quote>.
</para>
<para>
 This also makes for a good test for your browser configuration: If entering the
 URL <ulink url="http://config.privoxy.org/">http://config.privoxy.org/</ulink>
 takes you to a page saying <quote>This is Privoxy ...</quote>, everything is OK.
 If you get a page saying <quote>Privoxy is not working</quote> instead, then
 your browser didn't use <application>Privoxy</application> for the request,
 hence it could not be intercepted, and you have accessed the <emphasis>real</emphasis>
 web site at config.privoxy.org.
</para>
<para>
 Note that config.privoxy.org resolves to a public IP address.
 If you use config.privoxy.org as ping or traceroute target you will
 reach the system on the Internet (Privoxy can't intercept ICMP requests).
 If you want to ping the system Privoxy runs on,
 you should use its IP address or local DNS name (if it has got one).
</para>

</sect2>

<!--
 out of date 09/02/06 HB
<sect2 renderas="sect3" id="blocklist"><title>Do you still maintain the blocklists?</title>
 <para>
  No. The patterns for blocking now reside (among other things) in the <ulink
  url="../user-manual/actions-file.html">actions files</ulink>, which are
  actively maintained instead. See next question ...
</para>
</sect2>
-->
<sect2 renderas="sect3" id="newads"><title>How can I submit new ads, or report
problems?</title>
<para>
Please see the <link linkend="contact">Contact section</link> for
various ways to interact with the developers.
</para>

</sect2>

<sect2 renderas="sect3" id="newads2"><title>If I do submit missed ads, will
they be included in future updates?</title>
<para>
 Whether such submissions are eventually included in the
 <filename>default.action</filename> configuration file depends on how
 significant the issue is. We of course want to address any potential
 problem with major, high-profile sites such as <citetitle>Google</citetitle>,
 <citetitle>Yahoo</citetitle>, etc. Any site with global or regional reach,
 has a good chance of being a candidate. But at the other end of the spectrum
 are any number of smaller, low-profile sites such as for local clubs or
 schools. Since their reach and impact are much less, they are best handled by
 inclusion in the user's <filename>user.action</filename>, and thus would be
 unlikely to be included.
</para>

</sect2>


<sect2 renderas="sect3" id="noonecares"><title>Why doesn't anyone answer my support
request?</title>
<para>
Rest assured that it has been read and considered. Why it is not answered,
could be for various reasons, including no one has a good answer for it, no
one has had time to yet investigate it thoroughly, it has been reported
numerous times already, or because not enough information was provided to help
us help you. Your efforts are not wasted, and we do appreciate them.
</para>

</sect2>


<sect2 renderas="sect3" id="ip"><title>How can I hide my IP address?</title>
<para>
 If you run both the browser and &my-app; locally, you cannot hide your IP
 address with <application>Privoxy</application> or ultimately any other
 software alone. The server needs to know your IP address so that it knows
 where to send the responses back.
</para>
<para>
 There are many publicly usable "anonymous" proxies out there, which
 provide a further level of indirection between you and the web server.
</para>
<para>
 However, these proxies are called "anonymous" because you don't need
 to authenticate, not because they would offer any real anonymity.
 Most of them will log your IP address and make it available to the
 authorities in case you violate the law of the country they run in. In fact
 you can't even rule out that some of them only exist to *collect* information
 on (those suspicious) people with a more than average preference for privacy.
</para>
<para>
 If you want to hide your IP address from most adversaries,
 you should consider chaining <application>Privoxy</application>
 with <ulink url="https://www.torproject.org/">Tor</ulink>.
 The configuration details can be found in
 <ulink url="#TOR">How do I use <application>Privoxy</application> together
 with <application>Tor</application> section</ulink>
 just below.
</para>
</sect2>

<sect2 renderas="sect3" id="anonforsure">
<title>Can Privoxy guarantee I am anonymous?</title>
<para>
 No. Your chances of remaining anonymous are improved, but unless you
 <ulink url="#TOR">chain <application>Privoxy</application> with <application>Tor</application></ulink>
 or a similar proxy and know what you're doing when it comes to configuring
 the rest of your system, you should assume that everything you do
 on the Web can be traced back to you.
</para>
<para>
 <application>Privoxy</application> can remove various information about you,
 and allows <emphasis>you</emphasis> more freedom to decide which sites
 you can trust, and what details you want to reveal. But it neither
 hides your IP address, nor can it guarantee that the rest of the system
 behaves correctly. There are several possibilities how a web sites can find
 out who you are, even if you are using a strict <application>Privoxy</application>
 configuration and chained it with <application>Tor</application>.
</para>
<para>
 Most of <application>Privoxy's</application> privacy-enhancing features can be easily subverted
 by an insecure browser configuration, therefore you should use a browser that can
 be configured to only execute code from trusted sites, and be careful which sites you trust.
 For example there is no point in having <application>Privoxy</application>
 modify the User-Agent header, if websites can get all the information they want
 through JavaScript, ActiveX, Flash, Java etc.
</para>
<para>
 A few browsers disclose the user's email address in certain situations, such
 as when transferring a file by FTP. <application>Privoxy</application>
 does not filter FTP. If you need this feature, or are concerned about the
 mail handler of your browser disclosing your email address, you might
 consider products such as <application>NSClean</application>.
</para>
<para>
 Browsers available only as binaries could use non-standard headers to give
 out any information they can have access to: see the manufacturer's license
 agreement. It's impossible to anticipate and prevent every breach of privacy
 that might occur. The professionally paranoid prefer browsers available as
 source code, because anticipating their behavior is easier. Trust the source,
 Luke!
</para>

</sect2>

<sect2 renderas="sect3" id="proxytest">
<title>A test site says I am not using a Proxy.</title>
<para>
 Good! Actually, they are probably testing for some other kinds of proxies.
 Hiding yourself completely would require additional steps.
</para>
</sect2>

<sect2 renderas="sect3" id="tor"><title>How do I use Privoxy
 together with Tor?</title>
<para>
 Before you configure <application>Privoxy</application> to use
 <ulink url="https://www.torproject.org/">Tor</ulink>,
 please follow the <citetitle>User Manual</citetitle> chapters
 <ulink url="../user-manual/installation.html">2. Installation</ulink> and
 <ulink url="../user-manual/startup.html">5. Startup</ulink> to make sure
 <application>Privoxy</application> itself is setup correctly.
</para>
<para>
 If it is, refer to <ulink url="https://www.torproject.org/documentation.html">Tor's
 extensive documentation</ulink> to learn how to install <application>Tor</application>,
 and make sure <application>Tor</application>'s logfile says that
 <quote>Tor has successfully opened a circuit</quote> and it
 <quote>looks like client functionality is working</quote>.
</para>
<para>
 If either <application>Tor</application> or <application>Privoxy</application>
 isn't working, their combination most likely will neither. Testing them on their
 own will also help you to direct problem reports to the right audience.
 If <application>Privoxy</application> isn't working, don't bother the
 <application>Tor</application> developers. If <application>Tor</application>
 isn't working, don't send bug reports to the <application>Privoxy</application> Team.
</para>
<para>
 If you verified that <application>Privoxy</application> and <application>Tor</application>
 are working, it is time to connect them. As far as <application>Privoxy</application>
 is concerned, <application>Tor</application> is just another proxy that can be reached
 by socks4, socks4a and socks5. Most likely you are interested in <application>Tor</application>
 to increase your anonymity level, therefore you should use socks5, to make sure DNS
 requests are done through <application>Tor</application> and thus invisible to your
 local network. Using socks4a would work too, but with socks5 you get more precise error
 messages.
</para>

<para>
 <application>Privoxy's</application>
 <ulink url="../user-manual/config.html">main configuration file</ulink>
 is already prepared for <application>Tor</application>, if you are using a
 default <application>Tor</application> configuration and run it on the same
 system as &my-app;, you just have to edit the
 <ulink url="../user-manual/config.html#FORWARDING">forwarding section</ulink>
 and uncomment the line:
</para>
 <screen>
#        forward-socks5t             /     127.0.0.1:9050 .
</screen>
<para>
 Note that if you got Tor through one of the bundles, you may
 have to change the port from 9050 to 9150 (or even another one).
 For details, please check the documentation on the
 <ulink url="https://torproject.org/">Tor website</ulink>.
</para>

<para>
 This is enough to reach the Internet, but additionally you might want to
 uncomment the following forward rules, to make sure your local network is still
 reachable through Privoxy:
</para>
 <screen>
#        forward         192.168.*.*/     .
#        forward            10.*.*.*/     .
#        forward           127.*.*.*/     .
</screen>
<para>
 Unencrypted connections to systems in these address ranges will
 be as (un)secure as the local network is, but the alternative is
 that your browser can't reach the network at all. Then again,
 that may actually be desired and if you don't know for sure
 that your browser has to be able to reach the local network,
 there's no reason to allow it.
</para>
<para>
 If you want your browser to be able to reach servers in your local
 network by using their names, you will need additional exceptions
 that look like this:
</para>
 <screen>
#        forward           localhost/     .
</screen>
<para>
 Save the modified configuration file and open
 <ulink url="http://config.privoxy.org/show-status">http://config.privoxy.org/show-status</ulink>
 in your browser, confirm that <application>Privoxy</application> has reloaded its configuration
 and that there are no other forward lines, unless you know that you need them. If everything looks good,
 refer to
 <ulink url="https://wiki.torproject.org/noreply/TheOnionRouter/TorFAQ#IsMyConnectionPrivate">Tor
 Faq 4.2</ulink> to learn how to verify that you are really using <application>Tor</application>.
</para>
<para>
 Afterward, please take the time to at least skim through the rest
 of <application>Tor's</application> documentation. Make sure you understand
 what <application>Tor</application> does, why it is no replacement for
 application level security, and why you probably don't want to
 use it for unencrypted logins.
</para>
</sect2>

<sect2 renderas="sect3" id="sitebreak">
<title>Might some things break because header information or
content is being altered?</title>

<para>
 Definitely. It is common for sites to use browser type, browser version,
 HTTP header content, and various other techniques in order to dynamically
 decide what to display and how to display it. What you see, and what I see,
 might be very different. There are many, many ways that this can be handled,
 so having hard and fast rules, is tricky.
</para>

<para>
 The <quote>User-Agent</quote> is sometimes used in this way to identify
 the browser, and adjust content accordingly.
</para>

<para>
 Also, different browsers use different encodings of non-English
 characters, certain web servers convert pages on-the-fly according to the
 User Agent header. Giving a <quote>User Agent</quote> with the wrong
 operating system or browser manufacturer causes some sites in these languages
 to be garbled; Surfers to Eastern European sites should change it to
 something closer. And then some page access counters work by looking at the
 <quote>Referer</quote> header; they may fail or break if unavailable. The
 weather maps of Intellicast have been blocked by their server when no
 <quote>Referer</quote> or cookie is provided, is another example. (But you
 can forge both headers without giving information away). There are
 many other ways things can go wrong when trying to fool a web server. The
 results of which could inadvertently cause pages to load incorrectly,
 partially, or even not at all. And there may be no obvious clues as to just
 what went wrong, or why. Nowhere will there be a message that says
 <quote><emphasis>Turn off <literal>fast-redirects</literal> or else!</emphasis>
 </quote>
</para>

<para>
 Similar thoughts apply to modifying JavaScript, and, to a lesser degree,
 HTML elements.
</para>

<para>
 If you have problems with a site, you will have to adjust your configuration
 accordingly. Cookies are probably the most likely adjustment that may
 be required, but by no means the only one.
</para>

</sect2>


<sect2 renderas="sect3" id="caching">
<title>Can Privoxy act as a <quote>caching</quote> proxy to
speed up web browsing?</title>
<para>
 No, it does not have this ability at all. You want something like
 <ulink url="http://www.squid-cache.org/">Squid</ulink> or
 <ulink url="http://www.pps.jussieu.fr/~jch/software/polipo/">Polipo</ulink> for this.
 And, yes, before you ask, <application>Privoxy</application> can co-exist
 with other kinds of proxies like <application>Squid</application>.
 See the <ulink url="../user-manual/config.html#FORWARDING">forwarding
 chapter</ulink> in the <ulink url="../user-manual/index.html">user
 manual</ulink> for details.
</para>
</sect2>

<sect2 renderas="sect3" id="firewall">
<title>What about as a firewall? Can Privoxy protect me?</title>
<para>
 Not in the way you mean, or in the way some firewall vendors claim they can.
 <application>Privoxy</application> can help protect your privacy, but can't
 protect your system from intrusion attempts. It is, of course, perfectly possible
 to use <emphasis>both</emphasis>.
</para>
</sect2>

<sect2 renderas="sect3" id="wasted">
<title>I have large empty spaces / a checkerboard pattern now where
ads used to be. Why?</title>
<para>
 It is technically possible to eliminate banners and ads in a way that frees
 their allocated page space. This could easily be done by blocking with
 <application>Privoxy's</application> filters,
 and eliminating the <emphasis>entire</emphasis> image references from the
 HTML page source.
</para>
<para>
 But, this would consume considerably more CPU resources (IOW, slow things
 down), would likely destroy the layout of some web pages which rely on the
 banners utilizing a certain amount of page space, and might fail in other
 cases, where the screen space is reserved (e.g. by HTML tables for instance).
 Also, making ads and banners disappear without any trace complicates
 troubleshooting, and would sooner or later be problematic.
</para>
<para>
 The better alternative is to instead let them stay, and block the resulting
 requests for the banners themselves as is now the case. This leaves either
 empty space, or the familiar checkerboard pattern.
</para>
<para>
 So the developers won't support this in the default configuration, but you
 can of course define appropriate filters yourself to achieve this.
</para>
</sect2>

<sect2 renderas="sect3" id="ssl">
<title>How can Privoxy filter Secure (HTTPS) URLs?</title>
<para>
 If you enable
 <ulink url="../user-manual/actions-file.html#HTTPS-INSPECTION">https-inspection</ulink>
 <application>Privoxy</application> will impersonate the destination
 server and can thus filter encrypted requests and responses as well.
</para>
<para>
 Without
 <ulink url="../user-manual/actions-file.html#HTTPS-INSPECTION">https-inspection</ulink>
 secure HTTP connections are encrypted SSL sessions between your
 browser and the secure site, and there is little
 that <application>Privoxy</application> can do but hand the raw
 gibberish data though from one end to the other unprocessed.
</para>
<para>
 The only exception to this is blocking by host patterns, as the client needs
 to tell <application>Privoxy</application> the name of the remote server,
 so that <application>Privoxy</application> can establish the connection.
 If that name matches a host-only pattern, the connection will be blocked.
</para>
<para>
 As far as ad blocking is concerned, this is less of a restriction than it may
 seem, since ad sources are often identifiable by the host name, and often
 the banners to be placed in an encrypted page come unencrypted nonetheless
 for efficiency reasons, which exposes them to the full power of
 <application>Privoxy</application>'s ad blocking.
</para>
<para>
 <quote>Content cookies</quote> (those that are embedded in the actual HTML or
 JS page content, see <literal><ulink
 url="../user-manual/actions-file.html#FILTER-CONTENT-COOKIES">filter{content-cookies}</ulink></literal>),
 in an SSL transaction will be impossible to block under these conditions.
 Fortunately, this does not seem to be a very common scenario since most
 cookies come by traditional means.
</para>

</sect2>

<sect2 renderas="sect3" id="http2">
<title>Does Privoxy support HTTP/2?</title>
<para>
  Privoxy currently doesn't parse HTTP/2 but applications
  can tunnel HTTP/2 through Privoxy if Privoxy is configured
  to allow CONNECT requests (default) which are also used
  for HTTPS.
</para>
<para>
  Adding HTTP/2 support is on the
  <ulink url="https://www.privoxy.org/gitweb/?p=privoxy.git;a=blob_plain;f=TODO;hb=HEAD">TODO</ulink>
  list but currently nobody is known to work on it.
</para>
</sect2>

<sect2 renderas="sect3" id="secure">
<title>Privoxy runs as a <quote>server</quote>. How
secure is it? Do I need to take any special precautions?</title>
<para>
 On Unix-like systems, <application>Privoxy</application> can run as a non-privileged
 user, which is how we recommend it be run. Also, by default
 <application>Privoxy</application> listens to requests from <quote>localhost</quote>
 only.
</para>
<para>
 The server aspect of <application>Privoxy</application> is not itself directly
 exposed to the Internet in this configuration. If you want to have
 <application>Privoxy</application> serve as a LAN proxy, this will have to
 be opened up to allow for LAN requests. In this case, we'd recommend
 you specify only the LAN gateway address, e.g. 192.168.1.1, in the main
 <application>Privoxy</application> configuration file and check all <ulink
 url="../user-manual/config.html#ACCESS-CONTROL">access control and security
 options</ulink>. All LAN hosts can then use this as their proxy address
 in the browser proxy configuration, but <application>Privoxy</application>
 will not listen on any external interfaces. ACLs can be defined in addition,
 and using a firewall is always good too. Better safe than sorry.
</para>

</sect2>

<sect2 renderas="sect3" id="turnoff">
<title>Can I temporarily disable Privoxy?</title>
<para>
 &my-app; doesn't have a transparent proxy mode,
 but you can toggle off blocking and content filtering.
</para>
<para>
 The easiest way to do that is to point your browser
 to the remote toggle URL: <ulink
 url="http://config.privoxy.org/toggle">http://config.privoxy.org/toggle</ulink>.
</para>
<para>
 See the <ulink url="../user-manual/appendix.html#BOOKMARKLETS">Bookmarklets section</ulink>
 of the <citetitle>User Manual</citetitle> for an easy way to access this
 feature. Note that this is a feature that may need to be enabled in the main
 <filename>config</filename> file.
</para>
</sect2>


<sect2 renderas="sect3" id="reallyoff">
<title>When <quote>disabled</quote> is Privoxy totally
out of the picture?</title>
<para>
 No, this just means all optional filtering and actions are disabled.
 <application>Privoxy</application> is still acting as a proxy, but just
 doing less of the things that <application>Privoxy</application> would
 normally be expected to do. It is still a <quote>middle-man</quote> in
 the interaction between your browser and web sites. See below to bypass
 the proxy.
</para>
</sect2>

<sect2 renderas="sect3" id="turnoff2">
<title>How can I tell Privoxy to totally ignore certain sites?</title>
<para>
 Bypassing a proxy, or proxying based on arbitrary criteria, is purely a browser
 configuration issue, not a &my-app; issue. Modern browsers typically do have
 settings for not proxying certain sites. Check your browser's help files.
</para>
</sect2>


<sect2 renderas="sect3" id="crunch">
<title>My logs show Privoxy <quote>crunches</quote>
ads, but also its own internal CGI pages. What is a <quote>crunch</quote>?</title>
<para>
 A <quote>crunch</quote> means <application>Privoxy</application> intercepted
 <emphasis>something</emphasis>, nothing more. Often this is indeed ads or
 banners, but <application>Privoxy</application> uses the same mechanism for
 trapping requests for its own internal pages. For instance, a request for
 <application>Privoxy's</application> configuration page at: <ulink
 url="http://config.privoxy.org">http://config.privoxy.org</ulink>, is
 intercepted (i.e. it does not go out to the 'net), and the familiar CGI
 configuration is returned to the browser, and the log consequently will show
 a <quote>crunch</quote>.
</para>
<para>
 Since version 3.0.7, Privoxy will also log the crunch reason.
 If you are using an older version you might want to upgrade.
</para>
</sect2>

<sect2 renderas="sect3" id="downloads">
<title>Can Privoxy affect files that I download
from a webserver? FTP server?</title>
<para>
 From the webserver's perspective, there is no difference between
 viewing a document (i.e. a page), and downloading a file. The same is true of
 <application>Privoxy</application>. If there is a match for a <literal><ulink
 url="../user-manual/actions-file.html#BLOCK">block</ulink></literal> pattern,
 it will still be blocked, and of course this is obvious.
 </para>
 <para>
 Filtering is potentially more of a concern since the results are not always
 so obvious, and the effects of filtering are there whether the file is simply
 viewed, or downloaded. And potentially whether the content is some obnoxious
 advertisement, or Mr. Jimmy's latest/greatest source code jewel. Of course,
 one of these presumably is <quote>bad</quote> content that we don't want, and
 the other is <quote>good</quote> content that we do want.
 <application>Privoxy</application> is blind to the differences, and can only
 distinguish <quote>good from bad</quote> by the configuration parameters
 <emphasis>we</emphasis> give it.
</para>
<para>
 <application>Privoxy</application> knows the differences in files according
 to the <quote>Content Type</quote> as reported by the webserver. If this is
 reported accurately (e.g. <quote>application/zip</quote> for a zip archive),
 then <application>Privoxy</application> knows to ignore these where
 appropriate. <application>Privoxy</application> potentially can filter HTML
 as well as plain text documents, subject to configuration parameters of
 course. Also, documents that are of an unknown type (generally assumed to be
 <quote>text/plain</quote>) can be filtered, as will those that might be
 incorrectly reported by the webserver. If such a file is a downloaded file
 that is intended to be saved to disk, then any content that might have been
 altered by filtering, will be saved too, for these (probably rare) cases.
</para>
<para>
 Note that versions later than 3.0.2 do NOT filter document types reported as
 <quote>text/plain</quote>. Prior to this, <application>Privoxy</application>
 did filter this document type.
</para>
<para>
 In short, filtering is <quote>ON</quote> if a) the content type as reported
 by the webserver is appropriate <emphasis>and</emphasis> b) the configuration
 allows it (or at least does not disallow it). That's it. There is no magic
 cookie anywhere to say this is <quote>good</quote> and this is
 <quote>bad</quote>. It's the configuration that lets it all happen or not.
</para>
<para>
 If you download text files, you probably do not want these to be filtered,
 particularly if the content is source code, or other critical content. Source
 code sometimes might be mistaken for Javascript (i.e. the kind that might
 open a pop-up window). It is recommended to turn off filtering for download
 sites (particularly if the content may be plain text files and you are using
 version 3.0.2 or earlier) in your <filename>user.action</filename> file. And
 also, for any site or page where making <emphasis>any</emphasis> changes at
 all to the content is to be avoided.
</para>
<para>
 <application>Privoxy</application> does not do FTP at all, only HTTP
 and HTTPS (SSL) protocols.
</para>
</sect2>

<sect2 renderas="sect3" id="downloads2">
<title>I just downloaded a Perl script, and Privoxy
altered it! Yikes, what is wrong!</title>
<para>
 Please read above.
</para>
</sect2>

<sect2 renderas="sect3" id="hostsfile">
<title>Should I continue to use a <quote>HOSTS</quote> file for ad-blocking?</title>
<para>
 One time-tested technique to defeat common ads is to trick the local DNS
 system by giving a phony IP address for the ad generator in the local
 <filename>HOSTS</filename> file, typically using <literal>127.0.0.1</literal>, aka
 <literal>localhost</literal>. This effectively blocks the ad.
</para>
<para>
 There is no reason to use this technique in conjunction with
 <application>Privoxy</application>. <application>Privoxy</application>
 does essentially the same thing, much more elegantly and with much more
 flexibility. A large <filename>HOSTS</filename> file, in fact, not only
 duplicates effort, but may get in the way and seriously slow down your system.
 It is recommended to remove such entries from your <filename>HOSTS</filename> file. If you think
 your hosts list is neglected by <application>Privoxy's </application>
 configuration, consider adding your list to your <filename>user.action</filename> file:
</para>
 <screen>
  { +block }
   www.ad.example1.com
   ad.example2.com
   ads.galore.example.com
   etc.example.com</screen>
</sect2>

<sect2 renderas="sect3" id="seealso">
<title>Where can I find more information about Privoxy
and related issues?</title>
<!-- Include seealso.sgml boilerplate: -->
 &seealso;
<!-- end boilerplate -->

<!--
<para>
 Please see the
 <ulink url="../user-manual/seealso.html">user-manual</ulink> for
 others references.
</para>
-->
</sect2>

<sect2 renderas="sect3" id="microsuck">
<title>I've noticed that Privoxy changes <quote>Microsoft</quote> to
<quote>MicroSuck</quote>! Why are you manipulating my browsing?</title>

<para>
 We're not. The text substitutions that you are seeing are disabled
 in the default configuration as shipped. You have either manually
 activated the <quote><literal>fun</literal></quote> filter which
 is clearly labeled <quote>Text replacements for subversive browsing
 fun!</quote> or you are using an older Privoxy version and have implicitly
 activated it by choosing the <quote>Advanced</quote> profile in the
 web-based editor. Please upgrade.
</para>
</sect2>

<sect2 renderas="sect3" id="valid">
<title>Does Privoxy produce <quote>valid</quote> HTML (or XHTML)?</title>

<para>
 Privoxy generates HTML in both its own <quote>templates</quote>, and possibly
 whenever there are text substitutions via a &my-app; filter. While this
 should always conform to the HTML 4.01 specifications, it has not been
 validated against this or any other standard.
</para>
</sect2>

<sect2 renderas="sect3" id="surprise-privoxy">
<title>How did you manage to get Privoxy on my computer without my consent?</title>

<para>
 We didn't. We make Privoxy available for download, but we don't go
 around installing it on other people's systems behind their back.
 If you discover Privoxy running on your system and are sure you didn't
 install it yourself, somebody else did. You may not even be running
 the real Privoxy, but maybe something else that only pretends to be
 Privoxy, or maybe something that is based on the real Privoxy,
 but has been modified.
</para>
<para>
 Lately there have been reports of problems with some kind of
 "parental control" software based on Privoxy that came preinstalled on
 certain <ulink url="https://sourceforge.net/p/ijbswa/bugs/813/">ASUS Netbooks</ulink>.
 The problems described are inconsistent with the behaviour of official
 Privoxy versions, which suggests that the preinstalled software may
 contain vendor modifications that we don't know about and thus can't debug.
</para>
<para>
 Privoxy's <link linkend="copyright">license</link> allows vendor
 modifications, but the vendor has to comply with the license,
 which involves informing the user about the changes and to make
 the changes available under the same license as Privoxy itself.
</para>
<para>
 If you are having trouble with a modified Privoxy version,
 please try to talk to whoever made the modifications before
 reporting the problem to us. Please also try to convince
 whoever made the modifications to talk to us.  If you think
 somebody gave you a modified Privoxy version without complying
 to the license, please let us know.
</para>
</sect2>


</sect1>


<!--   ~~~~~       New section      ~~~~~     -->

<sect1 id="trouble">
<title>Troubleshooting</title>

<sect2 renderas="sect3" id="refused">
<title>I cannot connect to any websites. Or, I am getting
<quote>connection refused</quote> message with every web page. Why?</title>
<para>
 There are several possibilities:
</para>
<itemizedlist>
<listitem><para>
<application>Privoxy</application> is not running. Solution: verify
 that &my-app; is installed correctly, has not crashed, and is indeed running.
 Turn on <application>Privoxy's</application> logging, and look at the logs to see what they say.
</para></listitem>
 <listitem><para>Or your browser is configured for a different port than what
 <application>Privoxy</application> is using. Solution: verify that &my-app;
 and your browser are set to the same port (<literal>listen-address</literal>).
</para></listitem>
 <listitem><para>Or if using a forwarding rule, you have a configuration problem or a
 problem with a host in the forwarding chain. Solution: temporarily alter your
 configuration and take the forwarders out of the equation.
</para></listitem>
 <listitem><para>
  Or you have a firewall that is interfering and blocking you. Solution:
  try disabling or removing the firewall as a simple test.
 </para></listitem>
</itemizedlist>

</sect2>

<!--   ~~~~~       New section      ~~~~~     -->
<sect2 renderas="sect3" id="error503">
<title>Why am I getting a 503 Error (WSAECONNREFUSED) on every page?</title>
 <para>
  More than likely this is a problem with your TCP/IP networking. ZoneAlarm has
  been reported to cause this symptom -- even if not running! The solution is
  to either fight the ZA configuration, or uninstall ZoneAlarm, and then find
  something better behaved in its place. Other personal firewall type products
  may cause similar type problems if not configured correctly.
 </para>
</sect2>

<sect2 renderas="sect3" id="flushit">
<title>I just added a new rule, but the steenkin ad is
still getting through. How?</title>
<para>
 If the ad had been displayed before you added its URL, it will probably be
 held in the browser's cache for some time, so it will be displayed without
 the need for any request to the server, and <application>Privoxy</application>
 will not be involved. Flush the browser's caches, and then try again.
</para>

<para>
 If this doesn't help, you probably have an error in the rule you
 applied. Try pasting the full URL of the offending ad into <ulink
 url="http://config.privoxy.org/show-url-info">http://config.privoxy.org/show-url-info</ulink>
 and see if it really matches your new rule. Blocking ads is like blocking
 spam: a lot of tinkering is required to stay ahead of the game. And
 remember you need to block the URL of the ad in question, which may be
 entirely different from the site URL itself. Most ads are hosted on different
 servers than the main site itself. If you right-click on the ad, you should
 be able to get all the relevant information you need. Alternately, you can
 find the correct URL by looking at <application>Privoxy's</application> logs
 (you may need to enable logging in the main config file if its disabled).
</para>
<para>
 Below is a slightly modified real-life log snippet that originates with one
 requested URL: <literal>www.example.com</literal> (name of site was changed
 for this example, the number of requests is real). You can see in this the
 complexity of what goes into making up this one <quote>page</quote>. There
 are eight different domains involved here, with thirty two separate URLs
 requested in all, making up all manner of images, Shockwave Flash,
 JavaScript, CSS stylesheets, scripts, and other related content. Some of this
 content is obviously <quote>good</quote> or <quote>bad</quote>, but not all.
 Many of the more questionable looking requests, are going to outside domains
 that seem to be identifying themselves with suspicious looking names, making
 our job a little easier. &my-app; has <quote>crunched</quote> (meaning caught
 and BLOCKED) quite a few items in this example, but perhaps missed a few as well.
</para>
<screen>
<![CDATA[
Request: www.example.com/
Request: www.example.com/favicon.ico
Request: img.example.com/main.css
Request: img.example.com/sr.js
Request: example.betamarker.com/example.html
Request: www.lik-sang.com/Banners/bestsellers/skyscraper.php?likref=BSellers
Request: img.example.com/pb.png
Request: www.google-analytics.com/urchin.js crunch! (Blocked)
Request: www.advertising-department.com/ats/switch.ps.php?26856 crunch! (Blocked)
Request: img.example.com/p.gif
Request: www.popuptraffic.com/assign.php?l=example&mode=behind crunch! (Blocked)
Request: www.popuptraffic.com/scripts/popup.php?hid=5c3cf&tmpl=PBa.tmpl crunch! (Blocked)
Request: www.popuptraffic.com/assign.php?l=example crunch! (Blocked)
Request: www.lik-sang.com/Banners/best_sellers/best_sellers.css
Request: www.adtrak.net/adx.js crunch! (Blocked)
Request: img.example.com/hbg.gif
Request: img.example.com/example.jpg
Request: img.example.com/mt.png
Request: img.example.com/mm.png
Request: img.example.com/mb.png
Request: www.popuptraffic.com/scripts/popup.php?hid=a71b91fa5&tmpl=Ua.tmp crunch! (Blocked)
Request: www.example.com/tracker.js
Request: www.lik-sang.com/Banners/best_sellers/lsi_head.gif
Request: www.adtrak.net/adjs.php?n=020548130&what=zone:61 crunch! (Blocked)
Request: www.adtrak.net/adjs.php?n=463594413&what=zone:58&source=Ua crunch! (Blocked)
Request: www.lik-sang.com/Banners/best_sellers/bottomani.swf
Request: mmm.elitemediagroup.net/install.php?allowpop=no&popupmincook=0&allowsp2=1 crunch! (Blocked)
Request: www.example.com/tracker.js?screen=1400x1050&win=962x693
Request: www.adtrak.net/adlog.php?bannerid=1309&clientid=439&zoneid=61 crunch! (Blocked)
Request: 66.70.21.80/scripts/click.php?hid=5c3cf599a9efd0320d26&si
Request: 66.70.21.80/img/pixel.gif
Request: www.adtrak.net/adlog.php?bannerid=1309&clientid=439&zoneid=58&source=Ua&block=86400 crunch! (Blocked)
Request: 66.70.21.80/scripts/click.php?hid=a71b9f6504b0c5681fa5&si=Ua
]]>
</screen>
<para>
 Despite 12 out of 32 requests being blocked, the page looked, and seemed to
 behave perfectly <quote>normal</quote> (minus some ads, of course).
</para>

</sect2>

<sect2 renderas="sect3" id="badsite">
<title>One of my favorite sites does not work with Privoxy.
What can I do?</title>

<para>
 First verify that it is indeed a <application>Privoxy</application> problem,
 by toggling off <application>Privoxy</application> through <ulink
 url="http://config.privoxy.org/toggle">http://config.privoxy.org/toggle</ulink>
 (the toggle feature may need to be enabled in the main
 <filename>config</filename>),
 and then shift-reloading the problem page (i.e. holding down the shift key
 while clicking reload. Alternatively, flush your browser's disk and memory
 caches).
</para>

<para>
 If the problem went away, we know we have a configuration related problem.
 Now go to <ulink
 url="http://config.privoxy.org/show-url-info">http://config.privoxy.org/show-url-info</ulink>
 and paste the full URL of the page in question into the prompt. See which
 actions are being applied to the URL, and which matches in which actions
 files are responsible for that. It might be helpful also to look at your logs
 for this site too, to see what else might be happening (note: logging may need
 to be enabled in the main config file). Many sites are
 complex and require a number of related pages to help present their content.
 Look at what else might be used by the page in question, and what of that
 might be <emphasis>required</emphasis>.
 Now, armed with this information, go to
 <ulink
 url="http://config.privoxy.org/show-status">http://config.privoxy.org/show-status</ulink>
 and select the appropriate actions files for editing. </para>
<para>
 You can now either look for a section which disables the actions that
 you suspect to cause the problem and add a pattern for your site there,
 or make up a completely new section for your site. In any case, the recommended
 way is to disable only the prime suspect, reload the problem page, and only
 if the problem persists, disable more and more actions until you have
 identified the culprit. You may or may not want to turn the other actions
 on again. Remember to flush your browser's caches in between any such changes!
</para>
<para>
 Alternately, if you are comfortable with a text editor, you can accomplish
 the same thing by editing the appropriate actions file. Probably the easiest
 way to deal with such problems when editing by hand is to add your
 site to a <literal>{ fragile }</literal> section in <filename>user.action</filename>,
 which is an alias that turns off most <quote>dangerous</quote>
 actions, but is also likely to turn off more actions then needed, and thus lower
 your privacy and protection more than necessary,
</para>
<para>
 Troubleshooting actions is discussed in more detail in the <ulink
 url="../user-manual/appendix.html#ACTIONSANAT">User Manual appendix,
 Troubleshooting: the Anatomy of an Action</ulink>.
 There is also an <ulink
 url="../user-manual/actions-file.html#ACT-EXAMPLES">actions tutorial</ulink>
 with general configuration information and examples.
</para>
<para>
 As a last resort, you can always see if your browser has a setting that will
 bypass the proxy setting for selective sites. Modern browsers can do this.
</para>

</sect2>


<!--   ~~~~~       New section      ~~~~~     -->
<sect2 id="dun" renderas="sect3">
<title>After installing Privoxy, I have to log in
every time I start IE. What gives?</title>

<para>
 This is a quirk that affects the installation of
 <application>Privoxy</application>, in conjunction with Internet Explorer and
 Internet Connection Sharing on Windows 2000 and Windows XP. The symptoms may
 appear to be corrupted or invalid DUN settings, or passwords.
</para>

<para>
 When setting up an NT based Windows system with
 <application>Privoxy</application> you may find that things do not seem to be
 doing what you expect. When you set your system up you will probably have set
 up Internet Connection Sharing (ICS) with Dial up Networking (DUN) when
 logged in with administrator privileges. You will probably have made this DUN
 connection available to other accounts that you may have set-up on your
 system. E.g. Mum or Dad sets up the system and makes accounts suitably
 configured for the kids.
</para>

<para>
 When setting up <application>Privoxy</application> in this environment you
 will have to alter the proxy set-up of Internet Explorer (IE) for the
 specific DUN connection on which you wish to use
 <application>Privoxy</application>. When you do this the ICS DUN set-up
 becomes user specific. In this instance you will see no difference if you
 change the DUN connection under the account used to set-up the connection.
 However when you do this from another user you will notice that the DUN
 connection changes to make available to "Me only". You will also find that
 you have to store the password under each different user!
</para>

<para>
 The reason for this is that each user's set-up for IE is user specific. Each
 set-up DUN connection and each LAN connection in IE store the settings for
 each user individually. As such this enforces individual configurations
 rather than common ones. Hence the first time you use a DUN connection after
 re-booting your system it may not perform as you expect, and prompt you for
 the password. Just set and save the password again and all should be OK.
</para>

<para>
[Thanks to Ray Griffith for this submission.]
</para>
</sect2>


<!--   ~~~~~       New section      ~~~~~     -->
<sect2 id="ftp" renderas="sect3">
<title>I cannot connect to any FTP sites. Privoxy
 is blocking me.</title>
 <para>
  <application>Privoxy</application> cannot act as a proxy for FTP traffic,
  so do not configure your browser to use <application>Privoxy</application>
  as an FTP proxy. The same is true for <emphasis>any protocol other than HTTP
  or HTTPS (SSL)</emphasis>.
 </para>
 <para>
  Most browsers understand FTP as well as HTTP. If you connect to a site, with
  a URL like <literal>ftp://ftp.example.com</literal>, your browser is making
  an FTP connection, and not a HTTP connection. So while your browser may
  speak FTP, <application>Privoxy</application> does not, and cannot proxy
  such traffic.
 </para>
 <para>
  To complicate matters, some systems may have a generic <quote>proxy</quote>
  setting, which will enable various protocols, including
  <emphasis>both</emphasis> HTTP and FTP proxying! So it is possible to
  accidentally enable FTP proxying in these cases. And of course, if this
  happens, <application>Privoxy</application> will indeed cause problems since
  it does not know FTP. <![%p-newstuff;[Newer version will give a sane error
  message if a FTP connection is attempted.]]> Just disable the FTP setting
  and all will be well again.
 </para>
 <para>
  Will <application>Privoxy</application> ever proxy FTP traffic? Unlikely.
  There just is not much reason, and the work to make this happen is more than
  it may seem.
 </para>
</sect2>

<!--   ~~~~~       New section      ~~~~~     -->
<sect2 id="macosxie" renderas="sect3">
<title>In Mac OS X, I can't configure Microsoft Internet Explorer to use
 Privoxy as the HTTP proxy.</title>
 <para>
  Microsoft Internet Explorer (in versions like 5.1) respects system-wide
  network settings.  In order to change the HTTP proxy, open System
  Preferences, and click on the Network icon.  In the settings pane that
  comes up, click on the Proxies tab.  Ensure the "Web Proxy (HTTP)" checkbox
  is checked and enter <literal>127.0.0.1</literal> in the entry field.
  Enter <literal>8118</literal> in the Port field.  The next time you start
  IE, it should reflect these values.
 </para>
</sect2>

<!--   ~~~~~       New section      ~~~~~     -->
<sect2 renderas="sect3" id="macosxuninstall">
<title>In Mac OS X, I dragged the Privoxy folder to the trash in order to
 uninstall it. Now the finder tells me I don't have sufficient privileges to
 empty the trash.</title>
 <para>
 Note: This ONLY applies to privoxy 3.0.6 and earlier.
 </para>
 <para>
  Just dragging the <application>Privoxy</application> folder to the trash is
  not enough to delete it. <application>Privoxy</application> supplies an
  <application>uninstall.command</application> file that takes care of
  these details. Open the trash, drag the <application>uninstall.command</application>
  file out of the trash and double-click on it. You will be prompted for
  confirmation and the administration password.
 </para>
 <para>
  The trash may still appear full after this command; emptying the trash
  from the desktop should make it appear empty again.
 </para>
</sect2>

<!--   ~~~~~       New section      ~~~~~     -->
<sect2 renderas="sect3" id="macosximages">
<title>In Mac OS X Panther (10.3), images often fail to load and/or I
 experience random delays in page loading. I'm using
 <literal>localhost</literal> as my browser's proxy setting.</title>
 <para>
  We believe this is due to an IPv6-related bug in Mac OS X, but don't fully
  understand the issue yet. In any case, changing the proxy setting to
  <literal>127.0.0.1</literal> instead of <literal>localhost</literal>
  works around the problem.
 </para>
</sect2>

<!--   ~~~~~       New section      ~~~~~     -->
<sect2 renderas="sect3" id="macosxaccountdeletion">
<title>I just upgraded to Mac OS X 10.9 (Mavericks) and now &my-app; has stopped
 working.</title>
 <para>
  The upgrade process to Mac OS X Mavericks (10.9) from an earlier version of OS
  X deletes all user accounts that are either not part of OS X itself or are
  not interactive user accounts (ones you log in with). Since, for the sake of
  security, &my-app; runs as a non-privileged user that is created by its
  installer (_privoxy), it can no longer start up once that account gets deleted.
  The solution is to perform a complete uninstall using the supplied
  <application>uninstall.command</application> script (either back up your
  configuration files or select to not have the uninstaller remove them when it
  prompts you) and then reinstall &my-app; using the installer package and merge
  in your configuration.
 </para>
</sect2>

<sect2 renderas="sect3" id="nohostname">
<title>My logs show many <quote>Unable to get my own hostname</quote> lines.
Why?</title>
<para>
 <application>Privoxy</application> tries to get the hostname of the system
 its running on from the IP address of the system interface it is bound to
 (from the <filename>config</filename> file
 <emphasis>listen-address</emphasis> setting). If the system cannot supply
 this information, <application>Privoxy</application> logs this condition.
</para>
<para>
 Typically, this would be considered a minor system configuration error. It is
 not a fatal error to <application>Privoxy</application> however, but may
 result in a much slower response from <application>Privoxy</application> on
 some platforms due to DNS timeouts.
</para>
<para>
 This can be caused by a problem with the local <filename>hosts</filename>
 file. If this file has been changed from the original, try reverting it to
 see if that helps. Make sure whatever name(s) are used for the local system,
 that they resolve both ways.
</para>
<para>
 You should also be able to work around the problem with the
 <ulink url="../user-manual/config.html#HOSTNAME">hostname option</ulink>.
</para>
</sect2>

<sect2 renderas="sect3" id="inuse">
<title>When I try to launch Privoxy, I get an
error message <quote>port 8118 is already in use</quote> (or similar wording).
Why?</title>
<para>
 Port 8118 is <application>Privoxy's</application> default TCP
 <quote>listening</quote> port. Typically this message would mean that there
 is already one instance of <application>Privoxy</application> running, and
 your system is actually trying to start a second
 <application>Privoxy</application> on the same port, which will not work.
 (You can have multiple instances but they must be assigned different ports.)
 How and why this might happen varies from platform to platform, but you need
 to check your installation and start-up procedures.
</para>
</sect2>

<sect2 renderas="sect3" id="demoronizer">
<title>
 Pages with UTF-8 fonts are garbled.
</title>
<para>
 This may be the result of an overly aggressive filter. The filters that
 are enabled in the default configuration aren't expected to cause problems
 like this. If you enabled the <quote>demoronizer</quote> filter, please
 try temporarily disabling it.
</para>
<para>
 If that doesn't help, temporarily disable all filters to see if another
 filter could be the culprit. If the problem disappears, enable the filters
 one by one, until the problem reappears and the offending filter is found.
</para>
<para>
 Once the problem-causing filter is known, it can be fixed or disabled.
</para>
<para>
 Upgrading <application>Privoxy</application>, or going to the most recent
 <filename>default.action</filename> file available from <ulink
 url="https://www.privoxy.org/gitweb/?p=privoxy.git;a=blob_plain;f=default.action.master;hb=HEAD">git</ulink>
 might be worth a try, too.
</para>
</sect2>

<sect2 renderas="sect3" id="demoronizer2">
<title>
 Why are binary files (such as images) corrupted when Privoxy
 is used?
</title>
<para>
 This may also be caused by an (<link linkend="DEMORONIZER">overly aggressive
 filter</link> in conjunction with a web server that is misreporting the content
 type. By default binary files are exempted from
 <application>Privoxy's</application> filtering
 (unless the web server by mistake says the file is something else).
</para>
</sect2>

<sect2 renderas="sect3" id="demoronizer3">
<title>
 What is the <quote>demoronizer</quote> and why is it there?
</title>
<para>
 The original demoronizer was a Perl script that cleaned up HTML pages which
 were created with certain Microsoft products. MS has used proprietary extensions
 to standardized font encodings (ISO 8859-1), which has caused problems for pages
 that are viewed with non-Microsoft products (and are expecting to see a
 standard set of fonts). The demoronizer corrected these errors so the pages
 displayed correctly. <application>Privoxy</application> borrowed from this
 script, introducing a filter based on the original demoronizer, which in turn could
 correct these errors on the fly.
</para>
<para>
 But this is only needed in some situations, and will cause serious problems in some
 other situations.
</para>
<para>
 If you are using Microsoft products, you do not need it. If you need to view
 pages with UTF-8 characters (such as Cyrillic or Chinese), then it will
 cause corruption of the fonts, and thus <emphasis>should not be on</emphasis>.
</para>
<para>
 On the other hand, if you use non-Microsoft products, and you occasionally
 notice weird characters on pages, you might want to try it.
</para>
</sect2>

<sect2 renderas="sect3" id="windowopen">
<title>
 Why do I keep seeing <quote>PrivoxyWindowOpen()</quote> in raw source code?
</title>
<para>
 <application>Privoxy</application> is attempting to disable malicious
  <ulink url="http://en.wikipedia.org/wiki/Javascript">Javascript</ulink>
  in this case, with the <literal>unsolicited-popups</literal>
 filter. <application>Privoxy</application> cannot tell very well
 <quote>good</quote> code snippets from <quote>bad</quote> code snippets.
</para>
<para>
 If you see this in HTML source, and the page displays without problems, then
 this is good, and likely some pop-up window was disabled. If you see this
 where it is causing a problem, such as a downloaded program source code file,
 then you should set an exception for this site or page such that the
 integrity of the page stays in tact by disabling all filtering.
</para>
</sect2>

<sect2 renderas="sect3" id="dnserrors">
<title>
 I am getting too many DNS errors like <quote>404 No Such Domain</quote>. Why
 can't Privoxy do this better?
</title>
<para>
 There are potentially several factors here. First of all, the DNS resolution
 is done by the underlying operating system -- not
 <application>Privoxy</application> itself. <application>Privoxy</application>
 merely initiates the process and hands it off, and then later reports
 whatever the outcome was and tries to give a coherent message if there seems
 to be a problem. In some cases, this might otherwise be mitigated by the
 browser itself which might try some work-arounds and alternate approaches (e.g
 adding <quote>www.</quote> to the URL).
</para>
<para>
 In other cases, if <application>Privoxy</application> is being chained
 with another proxy, this could complicate the issue, and cause undue
 delays and timeouts. In the case of a <quote>socks4a</quote> proxy, the socks
 server handles all the DNS.  <application>Privoxy</application> would just be
 the <quote>messenger</quote> which is reporting whatever problem occurred
 downstream, and not the root cause of the error.
</para>
<![%p-newstuff;[
<para>
 In any case, versions newer than 3.0.3 include various improvements to help
 <application>Privoxy</application> better handle these cases.
</para>]]>
</sect2>

<sect2 renderas="sect3" id="allcpu">
<title>
 At one site Privoxy just hangs, and starts taking
 all CPU. Why is this?
</title>
<para>
 This is probably a manifestation of the <quote>100% cpu</quote> problem that
 occurs on pages containing many (thousands upon thousands) of blank lines. The blank lines
 are in the raw HTML source of the page, and the browser just ignores them. But the
 pattern matching in <application>Privoxy's</application> page filtering
 mechanism is trying to match against absurdly long strings and this becomes
 very CPU-intensive, taking a long, long time to complete.
</para>
<para>
 Until a better solution comes along, disable filtering on these pages,
 particularly the <literal>js-annoyances</literal> and
 <literal>unsolicited-popups</literal> filters. If you run into this problem
 with a recent &my-app; version, please send a problem report.
</para>
</sect2>

<sect2 renderas="sect3" id="slowcrawl">
<title>I just installed Privoxy, and all my
browsing has slowed to a crawl. What gives? </title>
<para>
 This should not happen, and for the overwhelming number of users world-wide,
 it does not happen. I would suspect some inadvertent interaction of software
 components such as anti-virus software, spyware protectors, personal
 firewalls or similar components. Try disabling (or uninstalling) these one
 at a time and see if that helps. Either way, if you are using a
 recent &my-app; version, please report the problem.
</para>
</sect2>

<sect2 renderas="sect3" id="preventcomp">
<title>Why do my filters work on some sites but not on others? </title>
<para>
 It's probably due to compression. It is a common practice for web servers to
 send their content <quote>compressed</quote> in order to speed things up, and
 then let the browser <quote>uncompress</quote> them. When compiled with zlib support
 &my-app; can decompress content before filtering, otherwise you may want to enable
<ulink
 url="../user-manual/actions-file.html#PREVENT-COMPRESSION">prevent-compression</ulink>.
</para>
<para>
 As of &my-app; 3.0.9, zlib support is enabled in the default builds.
</para>
</sect2>


<sect2 renderas="sect3" id="ssl-warnings">
<title>On some HTTPS sites my browser warns me about unauthenticated content,
 the URL bar doesn't get highlighted and the lock symbol appears to be broken.
 What's going on?</title>
<para>
 Probably the browser is requesting ads through HTTPS and &my-app;
 is blocking the requests. Privoxy's error messages are delivered
 unencrypted and while it's obvious for the browser that the HTTPS
 request is already blocked by the proxy, some warn about unauthenticated
 content anyway.
</para>
<para>
 To work around the problem you can redirect those requests to an invalid
 local address instead of blocking them. While the redirects aren't
 encrypted either, many browsers don't care. They simply follow the
 redirect, fail to reach a server and display an error message instead
 of the ad.
</para>
<para>
 To do that, enable logging to figure out which requests get blocked by
 &my-app; and add the hosts (no path patterns) to a section like this:
</para>
<screen>
<![CDATA[
{+redirect{http://127.0.0.1:0/} -block -limit-connect}
.ivwbox.de:443/
]]>
</screen>
<para>
 Additionally you have to configure your browser to contact
 <quote>127.0.0.1:0</quote> directly (instead of through &my-app;).
</para>
<para>
 To add a proxy exception in <application>Mozilla Firefox</application>
 open the <quote>Preferences</quote>, click the <quote>Settings</quote>
 button located on the <quote>Network</quote> tab in the <quote>Advanced</quote>
 section, and add <quote>127.0.0.1:0</quote> in the <quote>No Proxy for:</quote>
 field.
</para>
</sect2>


<sect2 renderas="sect3" id="se-linux">
<title>I get selinux error messages. How can I fix this?</title>
<para>
 Please report the problem to the creator of your selinux policies.
</para>
<para>
 The problem is that some selinux policy writers aren't familiar
 with the application they are trying to <quote>secure</quote> and
 thus create policies that make no sense.
</para>
<para>
 In <application>Privoxy's</application> case the problem usually
 is that the policy only allows outgoing connections for certain
 destination ports (e.g. 80 and 443). While this may cover the
 standard ports, websites occasionally use other ports as well.
 This isn't a security problem and therefore <application>Privoxy's</application>
 default configuration doesn't block these requests.
</para>
<para>
 If you really want to block these ports (and don't be able
 to load websites that don't use standard ports), you should
 configure Privoxy to block these ports as well, so it doesn't
 trigger the selinux warnings.
</para>
</sect2>


<sect2 renderas="sect3" id="gentoo-ricers">
<title>I compiled &my-app; with Gentoo's portage and it appears to be very slow. Why?</title>
<para>
 Probably you unintentionally compiled &my-app; without threading support
 in which case requests have to be serialized and only one can be served
 at the same time.
</para>
<para>
 Check your <quote>USE</quote> flags and make sure they include
 <quote>threads</quote>. If they don't, add the flag and rebuild &my-app;.
</para>
<para>
 If you compiled &my-app; with threading support (on POSIX-based systems),
 the <quote>Conditional #defines</quote> section on <ulink
 url="http://config.privoxy.org/show-status">http://config.privoxy.org/show-status</ulink>
 will list <quote>FEATURE_PTHREAD</quote> as <quote>enabled</quote>.
</para>
</sect2>

<sect2 renderas="sect3" id="tainted-sockets">
<title>What are tainted sockets and how do I prevent them?</title>
<para>
 &my-app; marks sockets as tainted when it can't use them to
 serve additional requests.
 This does not necessarily mean that something went wrong and
 information about tainted sockets is only logged if connection
 debugging is enabled (debug 2).
</para>
<para>
 For example server sockets that were used for CONNECT requests
 (which are used to tunnel https:// requests) are considered tainted
 once the client closed its connection to &my-app;.
 Technically &my-app; could keep the connection to the server open,
 but the server would not accept requests that do not belong to the
 previous TLS/SSL session (and the client may even have terminated
 the session).
</para>
<para>
 Server sockets are also marked tainted when a client requests a
 resource, but closes the connection before &my-app; has completely
 received (and forwarded) the resource to the client.
 In this case the server would (probably) accept additional requests,
 but &my-app; could not get the response without completely reading
 the leftovers from the previous response.
</para>
<para>
 These are just two examples, there are currently a bit more than
 25 scenarios in which a socket is considered tainted.
</para>
<para>
 While sockets can also be marked tainted as a result of a technical
 problem that may be worth fixing, the problem will be explicitly
 logged as error.
</para>
</sect2>

<sect2 renderas="sect3" id="pcre-stack-limit">
<title>After adding my custom filters, &my-app; crashes when visitting certain websites</title>
<para>
 This can happen if your custom filters require more memory than &my-app;
 is allowed to use.
 Usually the problem is that the operating system enforces a stack size limit
 that isn't sufficient.
</para>
<para>
 Unless the problem occurs with the filters available in the default configuration,
 this is not considered a Privoxy bug.
</para>
<para>
 To prevent the crashes you can rewrite your filter to use less resources,
 increase the relevant memory limit or recompile pcre to use less stack space.
 For details please see the
 <ulink url="http://pcre.org/original/doc/html/pcrestack.html">pcrestack man page</ulink>
 and the documentation of your operating system.
</para>
</sect2>

<sect2 renderas="sect3" id="file-permissions">
<title>What to do if editing the config file of privoxy is access denied?</title>
<para>
 Your userid probably isn't allowed to edit the file.
 <!--  show how to check permissions? -->
 On Windows you can use the windows equivalent of sudo:
</para>
 <screen>runas /user:administrator "notepad \privoxy\config.txt"</screen>

<para>
 or fix the file permissions:
</para>
<screen>C:\Privoxy>icacls config.txt
config.txt BUILTIN\Administrators:(I)(F)
           NT AUTHORITY\SYSTEM:(I)(F)
           BUILTIN\Users:(I)(RX)
           NT AUTHORITY\Authenticated Users:(I)(M)

Successfully processed 1 files; Failed processing 0 files

C:\Privoxy>icacls config.txt /grant Lee:F
processed file: config.txt
Successfully processed 1 files; Failed processing 0 files

C:\Privoxy>icacls config.txt
config.txt I3668\Lee:(F)
           BUILTIN\Administrators:(I)(F)
           NT AUTHORITY\SYSTEM:(I)(F)
           BUILTIN\Users:(I)(RX)
           NT AUTHORITY\Authenticated Users:(I)(M)

Successfully processed 1 files; Failed processing 0 files

C:\Privoxy></screen>

<para>
 or try to point-n-click your way through adjusting the file
 permissions in windows explorer.
</para>
</sect2>

</sect1>

  <!--   ~~~~~       New section      ~~~~~     -->
  <sect1 id="contact"><title>Contacting the developers, Bug Reporting and Feature Requests</title>
<!-- Include contacting.sgml  -->
 &contacting;
<!-- end contacting -->
  </sect1>

<!--   ~~~~~       New section      ~~~~~     -->
<sect1 id="copyright"><title>Privoxy Copyright, License and History</title>

 <!-- Include copyright.sgml -->
  &copyright;
 <!-- end -->


  <para>
   Portions of this document are <quote>borrowed</quote> from the original
   <application>Junkbuster</application> (tm) FAQ, and modified as
   appropriate for <application>Privoxy</application>.
  </para>

 <!--   ~~~~~       New section      ~~~~~     -->
 <sect2 id="privoxy-license"><title>License</title>
 <!-- Include copyright.sgml: -->
  &license;
 <!-- end copyright -->
 </sect2>
 <!--  ~  End section  ~  -->

 <!--   ~~~~~       New section      ~~~~~     -->
 <sect2 id="history"><title>History</title>
 <!-- Include history.sgml -->
  &history;
 <!-- end -->
 </sect2>

 </sect1>
 <!--  ~  End section  ~  -->


<!--   ~~~~~       New section      ~~~~~     -->
<!--
<sect1 id="seealso"><title>See also</title>
-->
<!-- Include seealso.sgml -->
<!--
 &see;
-->
<!-- end  -->
<!--
</sect1>
-->

 <!--
 This program is free software; you can redistribute it
 and/or modify it under the terms of the GNU General
 Public License as published by the Free Software
 Foundation; either version 2 of the License, or (at
 your option) any later version.

 This program is distributed in the hope that it will
 be useful, but WITHOUT ANY WARRANTY; without even the
 implied warranty of MERCHANTABILITY or FITNESS FOR A
 PARTICULAR PURPOSE.  See the GNU General Public
 License for more details.

 The GNU General Public License should be included with
 this file.  If not, you can view it at
 http://www.gnu.org/copyleft/gpl.html
 or write to the Free Software Foundation, Inc.,
 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA
-->

</article>