Several new Q/A's and other touch ups.

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

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 Written by and Copyright (C) 2001 the SourceForge
 Privoxy team. http://www.privoxy.org/

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

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

<pubdate>$Id: faq.sgml,v 1.32 2002/03/27 00:57:03 hal9 Exp $</pubdate>

<authorgroup>
 <author>
  <affiliation>
   <orgname>By: Privoxy Developers</orgname>
   </affiliation>
 </author>
</authorgroup>

<abstract>
 <para>
 This FAQ gives users and developers alike answers to frequently asked
 questions about <application>Privoxy</application>. 
 </para>
 <para>
 <application>Privoxy</application> is a web proxy with advanced filtering
 capabilities for protecting privacy, filtering web page content, managing
 cookies, controlling access, and removing ads, banners, pop-ups and other
 obnoxious Internet junk. <application>Privoxy</application> has a very
 flexible configuration and can be customized to suit individual needs and
 tastes. <application>Privoxy</application> has application for both
 stand-alone systems and multi-user networks.
</para>
<para>
 <application>Privoxy</application> is based on the code of the 
 <application>Internet Junkbuster</application>.
 <application>Junkbuster</application> was originally written by JunkBusters
 Corporation, and was released as free open-source software under the GNU GPL.
 Stefan Waldherr made many improvements, and started the SourceForge project
 to continue development.
</para>


 <para>
You can find the latest version of the document at <ulink url="http://www.privoxy.org/faq/">http://www.privoxy.org/faq/</ulink>.
Please see the Contact section in the 
<ulink url="http://www.privoxy.org/user-manual/contact.html">user-manual</ulink> if you want to contact the developers.
 </para>

<!--   <para> -->
<!--    Feel free to send a note to the developers at <email>ijbswa-developers@lists.sourceforge.net</email>. -->
<!--   </para> -->
</abstract>
</artheader>


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

<!--
<sect1 id="introduction"><title>Introduction</title>
<para>
   Fillme.
</para>
</sect1>
-->
<!--   ~~~~~       New section      ~~~~~     -->

<sect1 id="questions"><title>Frequently Asked Questions</title>

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

<sect2 id="general"><title>General Information</title>

<sect3 id="newjb"><title>What is this new version of <application>Privoxy</application>?</title>
 <para>
  The original <application>Internet Junkbuster</application> (tm) is a 
  copyrighted product of <ulink url="http://www.junkbusters.com">Junkbusters
  Corporation</ulink>. Development of this effort stopped some time ago as of
  version 2.0.2. Stefan Waldherr started the ijbswa project on <ulink
  url="http://sourceforge.net/projects/ijbswa/">Sourceforge</ulink> to rekindle
  development. Other developers subsequently joined with Stefan, and have
  since added many new features, refinements and enhancements. The result 
  of this effort is <application>Privoxy</application>.
 </para>
 <para>
  <application>Privoxy</application> started with the same
  <application>Junkbuster 2.0.2</application> code base, but has advanced
  significantly at this point. 
 </para>

</sect3>


<sect3>
<title id="whyprivoxy">Why <quote>Privoxy</quote>? Why a name change at all?</title>
<para>
 <application>Privoxy</application> is the 
 <quote><emphasis>Privacy Enhancing Proxy</emphasis></quote>.
</para>
<para>
 There are possible legal complications from the continued use of the 
 <application>Junkbuster</application> name, which is a trademark of 
 <ulink url="http://junkbusters.com">Junkbusters Corporation</ulink>.
 (There are, however, no objections from Junkbusters Corporation to the 
 <application>Privoxy</application> project itself, and they, in fact, still
 share our ideals and goals.)
</para>

<para>
 The developers also believed that there so many changes from the original 
 code, that it was time to make a clean break from the past and make 
 a name in their own right, especially now with the pending release of 
 version 3.0.

</para>
</sect3>


<sect3 id="differs"><title>How does <application>Privoxy</application> differ
from the old <application>Junkbuster?</application></title> 
<para>
  <application>Privoxy</application> picks up where
  <application>Junkbuster</application> left off. All the old features remain.
  The new <application>Privoxy</application> still blocks ads and banners,
  still manages cookies, and still helps protect your privacy. But, these are
  all enhanced, and many new features have been added, all in the same vein.
 </para>
 <para>
  The configuration has changed significantly as well. This is something that
  users will notice right off the bat. The <quote>blocklist</quote> file does
  not exist any more. This is replaced by <quote>actions</quote> files, such
  as <filename>default.actions</filename>. This is where most of the per site
  configuration is now.

 </para>
</sect3>

<sect3 id="features"><title>What are some of the new features?</title>
<!--
 This section is in both user-manual and faq. Please keep in sync!!!
-->
<para>
 <itemizedlist>

 <listitem>
  <para>
   Integrated browser based configuration and control utility (<ulink
   url="http://p.p">http://p.p</ulink>). Browser-based tracing of rule
   and filter effects.
  </para>
 </listitem> 
<!--
 <listitem>
  <para>
   Modularized configuration that will allow for system wide settings, and
   individual user settings. (not implemented yet, probably a 3.1 feature)
  </para>
 </listitem> 
-->
 <listitem>
  <para>
    Blocking of annoying pop-up browser windows.
  </para>
 </listitem> 

 <listitem>
  <para>
   HTTP/1.1 compliant (most, but not all 1.1 features are supported).
  </para>
 </listitem> 

 <listitem>
  <para>
   Support for Perl Compatible Regular Expressions in the configuration files, and 
   generally a more sophisticated and flexible configuration syntax over
   previous versions. 
  </para>
 </listitem> 

 <listitem>
  <para>
   GIF de-animation. 
  </para>
 </listitem> 
 
 <listitem>
  <para>
   Web page content filtering (removes banners based on size,
   invisible <quote>web-bugs</quote>, JavaScript, pop-ups, status bar abuse,
   etc.)
  </para>
 </listitem> 
 
 <listitem>
  <para>
   Bypass many click-tracking scripts (avoids script redirection).
 
  </para>
 </listitem> 
 
 <listitem>
  <para>
   Multi-threaded (POSIX and native threads).
  </para>
 </listitem> 

 <listitem>
  <para>
   Auto-detection and re-reading of config file changes.
  </para>
 </listitem> 

 <listitem>
  <para>
   User-customizable HTML templates (e.g. 404 error page).
  </para>
 </listitem> 

 <listitem>
  <para>
   Improved cookie management features (e.g. session based cookies).
  </para>
</listitem> 

 <listitem>
  <para>
   Builds from source on most UNIX-like systems. Packages available for: Linux
   (RedHat, SuSE, or Debian), Windows, Sun Solaris, Mac OSX, OS/2, HP-UX 11 and AmigaOS.
 
  </para>
 </listitem> 

 <listitem>
  <para>
   In addition, the configuration is much more powerful and versatile over-all.
  </para>
</listitem> 

 </itemizedlist>
</para>

</sect3>

<sect3 id="proxymoron"><title>What is a <quote>proxy</quote>? How does
<application>Privoxy</application> work? </title>
 <para>
  When you connect to a web site with <application>Privoxy</application>, 
  you are really connecting to your locally running version of 
  <application>Privoxy</application>. <application>Privoxy</application>
  intercepts your requests for the web page, and relays that to the 
  <quote>real</quote> web site. The web site sends the HTTP data stream 
  back to <application>Privoxy</application>, where
  <application>Privoxy</application> can work its magic before it 
  relays this data back to your web browser.
 </para>

 <para>
  Since <application>Privoxy</application> sits between you and the 
  WWW, it is in a position to intercept and completely manage all web traffic and 
  HTTP content before it gets to your browser.
  <application>Privoxy</application> uses various programming methods to do
  this, all of which is under your control via the various configuration
  files and options.
 </para>

 <para>
  There are many kinds of proxies. <application>Privoxy</application> best 
  fits the <quote>filtering proxy</quote> category.
 </para>

</sect3>


<sect3>
<title id="knows">How does <application>Privoxy</application> know what is
an ad, and what is not?</title>
<para>
 <application>Privoxy</application> processes all the raw content of every 
 web page. So it reads everything on each page. It then compares this to the
 rules as set up in the configuration files, and looks for any matches to
 these rules. <application>Privoxy</application> makes heavy use of
 <quote>regular expressions</quote>. (If you are not familiar with regular
 expressions, it is explained briefly in <ulink
 url="../user-manual/appendix.html">the user manual</ulink>.) Regular
 expressions facilitate matching of one text string against another, using
 wildcards to build complex patterns. So <application>Privoxy</application>
 will typically look for URLs and other content that match certain key words
 and expressions as defined in the configuration files. For instance a URL
 that contains <quote>/banners</quote>, has a high probability of containing
 ad banners, and thus would be a prime candidate to have a matching rule.
</para>
<para>
 So <application>Privoxy</application> will look for these kinds of obvious 
 looking culprits. And also, will use lists of known organizations that
 specialize in ads. Again, using complex patterns to match as many potential 
 combinations as possible since there tend to be many, many variations used by 
 advertisers, and new ones are being introduced all the time.
</para>
</sect3>

<sect3>
<title id="mistakes">Can <application>Privoxy</application> 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 something by mistake. There is a good chance you may run 
 into such a situation 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 appendix below</link>.)
</para>

</sect3>


<sect3 id="browsers2"><title>My browser does the same things as
<application>Privoxy</application>. Why should I use
<application>Privoxy</application> 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 much more
  versatile and powerful, and can do a number of things that browsers just can't.
 </para>
 <para>
  In addition, a proxy is good choice if you use multiple browsers, or 
  have a LAN with multiple computers. This way all the configuration 
  is in one place, and you don't have to maintain a similar configuration 
  for possibly many browsers.

 </para>
</sect3>



<sect3 id="license"><title>Is there is a license or fee? What about a 
warranty? Registration?</title>
 <para>
  <application>Privoxy</application> is licensed under the 
  GNU General Public License (GPL). It is free to use, copy, 
  modify or distribute as you wish under the terms of this license.
  See <ulink
  url="http://www.gnu.org/copyleft/gpl.html">http://www.gnu.org/copyleft/gpl.html</ulink>
  for specifics.
  </para>
 <para>
  There is no warranty of any kind, expressed, implied or otherwise. That is
  something that would cost real money ;-) There is no registration either.
  <application>Privoxy</application> really is <emphasis>free</emphasis>
  in every respect!

 </para>
</sect3>

<sect3 id="jointeam"><title>I would like to help you, what do I do?</title>

<sect4 id="jointeam-money"><title>Money Money Money</title>
<para>
 We, of course, welcome donations and use the money for domain registering,
 regular world-wide get-togethers (hahaha). Anyway, we'll soon describe the
 process how to donate money to the team.
</para>
</sect4>

<sect4 id="jointeam-work"><title>You want to work with us?</title>
<para>
   Well, helping the team is always a good idea. We welcome new developers,
   RPM gurus or documentation makers. Simply get an account on sourceforge.net
   and mail your id to the developer mailing list. Then read the
   section Quickstart in the <ulink url="http://privoxy.org/developer-manual/quickstart.html">
   Developer's Manual</ulink>.
</para>
<para>
 Once we have added you to the team, you'll have write access to the CVS
 repository, and together we'll find a suitable task for you.
</para>
</sect4>

</sect3>

</sect2>


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

<sect2 id="installation"><title>Installation</title>

<sect3 id="whichbrowsers">
<title>Which browsers are supported by <application>Privoxy</application>?</title>
<para>
 Any browser that can be configured to use a <quote>proxy</quote>, which 
 should be virtually all browsers. Direct browser support is not necessary
 since <application>Privoxy</application> runs as a separate application and
 just exchanges standard HTML data with your browser.
</para>
</sect3>

<sect3 id="whichos">
<title>Which operating systems are supported?</title>
<para>
 Right now Win32, Mac OSX, OS/2, AmigaOS, Linux, and many 
 flavors of Unix.
</para>

<para>
 Source code is available, so porting to other operating systems, 
 is always a possibility.

</para>
</sect3>

<sect3 id="newinstall"><title>Can I install  
 <application>Privoxy</application> over <application>Junkbuster</application>?</title>
 <para>
   We recommend you uninstall <application>Junkbuster</application>
   first to minimize conflicts and confusion. You may want to 
   save your old configuration files for future reference. The configuration
   is substantially changed.
 </para>
 <para>
  See the <ulink
  url="../user-manual/index.html">user-manual</ulink> for
  platform specific installation instructions. [FIXME: This is meant for after
  the name change for 3.0!]
 </para>
 <para>
  Note: Some installers may automatically uninstall
  <application>Junkbuster</application>, if present!
 </para>
 
</sect3>

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

<para>
 All browsers must 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. See below.
 Also, you should flush your browser's memory and disk cache to get rid of any
 cached items.

</para>

</sect3>


<sect3 id="localhost"><title>What is the proxy address of <application>Privoxy</application>?</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 <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 have <application>Privoxy</application> to run on a different port with the
  <emphasis>listen-address</emphasis> config option). 
 </para>
 <para>
  When configuring your browser's proxy settings you typically enter
  the word <quote>localhost</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. Port assignment would be 
  same as above.
 </para>
 <para>
  <application>Privoxy</application> does not currently handle
  protocols such as FTP, SMTP, IM, IRC, ICQ, or other Internet
  protocols. 
 </para>
</sect3>

<sect3>
<title id="nothing">I just installed <application>Privoxy</application>, 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>. This should give you 
 a banner that says <quote>This is Privoxy</quote> and 
 access to <application>Privoxy's</application> internal configuration. 
 If you see this, then you are good to go. If not, the browser or 
 <application>Privoxy</application> are not set up correctly.

</para>

</sect3>

</sect2>


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

<sect2 id="configuration"><title>Configuration</title>

<sect3 id="newconfig"><title>Can I use my old config files?</title>
 <para>
   There are major changes to <application>Junkbuster</application> 
   configuration from version 2.0.x to 2.9.x and later. The older files will
   not work at all. If this is the case, you will need to re-enter your old
   data into the new configuration structure. This is probably also a good 
   recommendation even if upgrading from 2.9.x to 3.x since there were 
   many minor changes along the way.
 </para>
</sect3>

<sect3>
<title id="actionsfile">What is an <quote>actions</quote> file?</title>

<para>
 <quote>actions</quote> files are where various actions that
 <application>Privoxy</application> might take, are configured. 
 Typically, you would define a set of default actions that apply 
 to all URLs, then add exceptions to these defaults.
</para>
 
<para>
 Actions can be defined on a per site basis, or for groups of sites. Actions
 can also be grouped together and then applied to one or more sites. There
 are many possible actions that might apply to any given site. As an example,
 if we are blocking cookies as one of our default
 <application>actions</application>, but need to accept cookies from a given
 site, we would define this in our <quote>actions</quote> file.

</para>

<para>
 <application>Privoxy</application> comes with several default
 <application>actions</application> files, with varying degrees 
 of filtering and blocking, as starting points for your own 
 configuration (see below).
</para>

</sect3>

<sect3 id="actionss">
<title>The <quote>actions</quote>concept confuses me. Please list 
some of these <quote>actions</quote>.</title>
<para>
 These are all explained in the 
 <ulink url="../user-manual/configuration.html#ACTIONSFILE">user-manual</ulink>.
 Please refer to that.
</para>
</sect3>


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

<para>
 The easiest way to do this, is to access <application>Privoxy</application>
 with your web browser at <ulink url="http://p.p/">http://p.p/</ulink>, 
 and then select 
 "<ulink url="http://www.privoxy.org/config/edit-actions">Edit the actions list</ulink>"
 from the selection list. You can also do this by editing the appropriate 
 file with a text editor.
</para>

<para>
 Please see the 
 <ulink
 url="../user-manual/configuration.html#ACTIONSFILE">user-manual</ulink> for a
 detailed explanation of these and other configuration files, and their
 various options and syntax.
</para>
</sect3>


<!--
FIXME: Commenting these out until we have some data there. HB 03/17/02.

<sect3 id="yahoo"><title>How can I make my Yahoo account work?</title>
 <para>
   Fillme.
 </para>
</sect3>

<sect3 id="hotmail"> <title>How can I make my Hotmail account work?</title>
  <para>
   Fillme.
  </para>
</sect3>

<sect3 id="gmx"> <title>How can I make my GMX account work?</title>
 <para>
   Fillme.
 </para>
</sect3>
-->

<sect3 id="configfiles"> <title>What are the differences between
intermediate.action, basic.action, etc.?</title>
 <para>
Configuring <application>Privoxy</application> is not easy. To help you get
started, we provide you with three different default configurations. The
following table shows you, which features are enabled in each configuration.
 </para>
 <para>
<table frame=all><title>Default Configurations</title>
<tgroup cols=5 align=left colsep=1 rowsep=1>
<colspec colname=c1>
<colspec colname=c2>
<colspec colname=c3>
<colspec colname=c4>
<colspec colname=c5>
<thead>
<row>
  <entry>Feature</entry>
  <entry>default.action</entry>
  <entry>basic.action</entry>
  <entry>intermediate.action</entry>
  <entry>advanced.action</entry>
</row>
</thead>

<!--  <tfoot> -->
<!--  <row> -->
<!--    <entry>f1</entry> -->
<!--    <entry>f2</entry> -->
<!--    <entry>f3</entry> -->
<!--    <entry>f4</entry> -->
<!--    <entry>f5</entry> -->
<!--  </row> -->
<!--  </tfoot> -->

<tbody>
<!-- new row -->
<row>
  <entry>ad-filtering</entry>
  <entry>?</entry>
  <entry>x</entry>
  <entry>x</entry>
  <entry>x</entry>
</row>
<!-- new row -->
<row>
  <entry>blank image</entry>
  <entry>?</entry>
  <entry>x</entry>
  <entry>x</entry>
  <entry>x</entry>
</row>
<!-- new row -->
<row>
  <entry>de-animate GIFs</entry>
  <entry>?</entry>
  <entry>x</entry>
  <entry>x</entry>
  <entry>x</entry>
</row>
<!-- new row -->
<row>
  <entry>referer forging</entry>
  <entry>?</entry>
  <entry>x</entry>
  <entry>x</entry>
  <entry>x</entry>
</row>
<!-- new row -->
<row>
  <entry>jon's +no-cookies-keep (i.e. session cookies only)</entry>
  <entry>?</entry>
  <entry>x</entry>
  <entry>x</entry>
  <entry>x</entry>
</row>
<!-- new row -->
<row>
  <entry>no-popup windows</entry>
  <entry>?</entry>
  <entry></entry>
  <entry>x</entry>
  <entry>x</entry>
</row>
<!-- new row -->
<row>
  <entry>fast redirects</entry>
  <entry>?</entry>
  <entry></entry>
  <entry>x</entry>
  <entry>x</entry>
</row>
<!-- new row -->
<row>
  <entry>hide-referrer</entry>
  <entry>?</entry>
  <entry></entry>
  <entry>x</entry>
  <entry>x</entry>
</row>
<!-- new row -->
<row>
  <entry>hide-useragent</entry>
  <entry>?</entry>
  <entry></entry>
  <entry>x</entry>
  <entry>x</entry>
</row>
<!-- new row -->
<row>
  <entry>content-modification</entry>
  <entry>?</entry>
  <entry></entry>
  <entry></entry>
  <entry>x</entry>
</row>
<!-- new row -->
<row>
  <entry>feature-x</entry>
  <entry>?</entry>
  <entry></entry>
  <entry></entry>
  <entry></entry>
</row>
<!-- new row -->
<row>
  <entry>feature-y</entry>
  <entry>?</entry>
  <entry></entry>
  <entry></entry>
  <entry></entry>
</row>
<!-- new row -->
<row>
  <entry>feature-z</entry>
  <entry>?</entry>
  <entry></entry>
  <entry></entry>
  <entry></entry>
</row>
<!-- finish -->
</tbody>
</tgroup>
</table>
</para>
</sect3>

<sect3 id="browseconfig"> <title>Why can I change the configuration with a
browser? Does that not raise security issues?</title>
 <para>
What I don't understand, is how I can browser edit the config file as a
regular user, while the whole /etc/privoxy hierarchy belongs to the user
"privoxy", with only 644 perms.
 </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 "privoxy", it can
update the config files.
 </para>
 <para>
If you don't like this, setting "enable-edit-actions 0" in the config file
will disable the browser-based editor.  If you're that paranoid, you should
also consider setting "enable-remote-toggle 0" to prevent browser-based
enabling/disabling of <application>Privoxy</application>.
 </para>
 <para>
Note that normally only local users can connect to <application>Privoxy</application>, so this is not
(normally) a security problem.
 </para>
</sect3>


<sect3>
<title id="filterfile">What is <quote>default.filter</quote>?</title>
<para>
 The <quote>default.filter</quote> file is used to <quote>filter</quote> any
 web page content. By <quote>filtering</quote> we mean it can modify, remove, 
 or change <emphasis>anything</emphasis> on the page, including HTML tags, and
 JavaScript. Regular expressions are used to accomplish this, and operate 
 on a line by line basis. This is potentially a very powerful feature, but
 requires some expertise. 
</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 see
 some of things it can be used for.
</para>

<para>
 Presently, there is no GUI editor option for this part of the configuration, 
 but you can disable/enable various sections of the included default 
 file with the <quote>Actions List Editor</quote> from your browser.
</para>

</sect3>

<sect3>
<title id="lanconfig">How can I set up <application>Privoxy</application> to act as a proxy for my 
 LAN?</title>
<para>
 By default, <application>Privoxy</application> only responds to requests 
 from localhost. To have it act as a server for a network, this needs to be 
 changed in the main config file where the <application>Privoxy</application>
 configuration is located. In that file is a <quote>listen-address</quote> 
 option. It 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:
</para>

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

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

</sect3>


<sect3>
<title id="noseeum">Instead of ads, now I get a checkerboard pattern. I don't want to see anything.</title>
<para>
 This is a configuration option for images that
 <application>Privoxy</application> is stopping. You have the choice <!-- of
 the --> <!-- <application>Privoxy</application> logo, --> of a checkerboard
 pattern, a transparent 1x1 GIF image (aka <quote>blank</quote>), or a custom
 URL of your choice. Note that to fit this category, the URL must match both 
 the <quote>+image</quote> and <quote>+block</quote> actions.
</para>

<para>
 If you want to see nothing, then change the <quote>+image-blocker</quote> 
 action to <quote>+image-blocker{blank}</quote>. This can be done from the 
 <quote>Edit Actions List</quote> selection at <ulink
 url="http://p.p/">http://p.p/</ulink>. Or by hand editing the appropriate 
 actions file. This will only effect what is defined as <quote>images</quote>
 though. Also, any URLs that generate the bright red <quote>Blocked</quote>
 banner, can be moved to the <quote>+image-blocker</quote> section for the
 same reason.

</para>

</sect3>


<sect3>
<title id="whyseeum">Why would anybody want to see a checkerboard pattern?</title>
<para>
 This can be helpful for troubleshooting problems. It might also be good 
 for anyone new to <application>Privoxy</application> so that they can 
 see if their favorite pages are displaying correctly, and
 <application>Privoxy</application> is not inadvertently removing something 
 important.
</para>

</sect3>

<sect3>
<title id="blockedisugly">I see large red banners on some pages that say 
<quote>Blocked</quote>. Why and how do I get rid of this?</title>
<para>
 These are URLs that match something in one of 
 <application>Privoxy's</application> block actions (+block). It is meant
 to be a warning so that you know something has been blocked and an easy way
 for you to see why. These are handled differently than what has been defined
 explicitly as <quote>images</quote> (e.g. ad banners). Depending on the 
 URL itself, it is sometimes hard for <application>Privoxy</application> to 
 really know whether it is indeed an ad image or not.
</para>

<para>
 If you want them to be treated as if they were images, so that they can be
 made invisible, then move the offending URL from the <quote>+block</quote>
 section to the <quote>+imageblock</quote> section of your actions file. Just
 be forewarned, if make any URL is made <quote>invisible</quote>, you may not
 have any inkling that something has been removed from that page.
</para>
<para>
 Alternately, you could modify the <quote><filename>block</filename></quote>
 HTML template that is used by <application>Privoxy</application> to display
 this, and make it something more to your liking.
</para>

</sect3>

<sect3 id="alliseeisred">
<title>I cannot see all of the <quote>Blocked</quote> page banner. All I
see is a bright red square.</title>
<para>
 There is not enough space to fit the entire page. Try right clicking on the
 visible, red portion, and select <quote>Show Frame</quote>, or equivalent.
 This will usually allow you to see the entire Privoxy <quote>Blocked</quote>
 page, and from there you can see just what is being blocked, and why.
</para>
</sect3>

<sect3 id="otherproxy">
<title>How can I make <application>Privoxy</application> work with other 
proxies like <application>Squid</application>?</title>
<para>
 This can be done. See the <ulink
 url="../user-manual/configuration.html#FORWARDING">user manual</ulink>, 
 which describes how to do this.

</para>

</sect3>

</sect2>

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

<sect2 id="misc"><title>Miscellaneous</title>

<sect3>
<title id="slowsme">How much does <application>Privoxy</application> slow my browsing down? This 
has to add extra time to browsing.</title>
<para>
 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 being 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.
</para>

<para>
 <quote>Filtering</quote> via the <filename>filterfile</filename> 
 mechanism may cause a perceived slowdown, since the entire page is buffered
 before displaying. See below.
</para>

</sect3>



<sect3 id="loadingtimes"><title>I noticed considerable
delays in page requests compared to the old Junkbuster. What's wrong?</title>
<para>
Using the default filtering configuration, I noticed considerable delays in
page requests compared to the old Junkbuster. Loading pages with large contents
seemed to take forever, then suddenly delivering all the content at once.
 </para>
<para>
The whole content must be loaded in order to filter, and nothing is is
sent to the browser during this time. The loading time does not really
change 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". 
 </para>
<para>
To modify the content of a page (i.e. make frames resizeable again, etc.) and
not just replace ads, <application>Privoxy</application> needs to download the
entire page first, do its content magic and then send the page to the browser.
</para>
</sect3>


<sect3 id="configurl"><title>What is the "http://p.p/"?</title>
<para>
Since <application>Privoxy</application> sits between your web browser and the Internet, it can be
programmed to handle certain pages specially.
</para>

<para>
With recent versions of <application>Privoxy</application> (version 2.9.x), you can get some
information about <application>Privoxy</application> and change some settings by going to
http://p.p/ or, equivalently, http://www.privoxy.org/config/
(Note that p.p is far easier to type but may not work in some
configurations).
</para>

<para>
These pages are *not* forwarded to a server on the Internet - instead they are
handled by a special web server which is built in to <application>Privoxy</application>.
</para>

<para>
If you are not running <application>Privoxy</application>, then http://p.p/ will fail, and
http://www.privoxy.org/config/ will return a web page telling you
you're not running <application>Privoxy</application>.
</para>

<para>
If you have version 2.0.2, then the equivalent is
http://example.com/show-proxy-args (but you get far less information, and you
should really consider upgrading to 2.9.x).
</para>
</sect3>

<!--
FIXME: commented out until we have data. HB 03/18/02.

<sect3 id="badfiledesc"><title>I get the message 'Bad File Descriptor', why?</title>
<para>
   Fillme.
</para>
</sect3>

<sect3 id="proxy-chaining"><title>How do I chain <application>Privoxy</application> with other proxies
(e.g. squid)?</title>
<para>
   Fillme.
</para>
</sect3>
-->

<sect3 id="blocklist"><title>Do you still maintain the blocklists?</title>
<para>
    No. The format of the blocklists has changed significantly in the versions
    2.9.x. Once we have released the new version, there will again be
    blocklists that you can update automatically.
</para>
</sect3>

<sect3 id="newads"><title>How can I submit new ads?</title>
<para>
    As of now, please discontinue to submit new ad blocking infos. Once we
    have released the new version, there will again be a form on the website,
    which you can use to contribute new ads.
</para>
</sect3>

<sect3 id="ip"><title>How can I hide my IP address?</title>
<para>
 You cannot hide your IP address with <application>Privoxy</application> or any other software, since
the server needs to know your IP address to send the answer to you.
</para>
<para>
Fortunately there are many publicly usable anonymous proxies out there, which
solve the problem by providing a further level of indirection between you and
the web server, shared by many people and thus letting your requests "drown"
in white noise of unrelated requests as far as user tracking is concerned.
</para>
<para>
Most of them will, however, log your IP address and make it available to the
authorities in case you abuse that anonymity for criminal purposes. 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>
You can find a list of anonymous public proxies at <ulink
url="http://www.multiproxy.org/anon_list.htm">multiproxy.org</ulink> and many
more through Google.
</para>
</sect3>

<!--  <sect3 id="image"><title>What is the imagefile (simage.ini, etc.) for?</title> -->
<!--  <para> -->
<!--   Anytime <application>Privoxy</application> determines (with the help of the blocklist) that a URL -->
<!--   contains an advertisement, it has to decide whether this advertisement is an -->
<!--   image or not. <application>Privoxy</application> uses the imagefile for that purpose. -->
<!--  </para> -->
<!--  </sect3> -->

<sect3>
<title id="anonforsure">Can <application>Privoxy</application> guarantee I am anonymous?</title>
<para>
 No. Your chances of remaining anonymous are greatly improved, but unless you
 are an expert on Internet security it would be safest to 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. But it's still possible that web sites can find out who you
 are. Here's one way this can happen.
</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>

</sect3>

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

<para>
 Definitely. More and more sites use HTTP header content to decide what to
 display and how to display it. There is many ways that this can be handled, 
 so having hard and fast rules, is tricky.
</para>

<para>
 <quote>USER AGENT</quote> in particular is often used in this way to identify
 the browser, and adjust content accordingly. Changing this now is not
 recommended, since so many sites do look for this. You may get undesirable 
 results by changing this.
</para>

<para>
 For instance, different browsers use different encodings of Russian and Czech
 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. There are
 many, many other ways things can go wrong when trying to fool a web server.
</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>

</sect3>


<sect3>
<title id="caching">Can <application>Privoxy</application> 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> for this. And, yes, 
 before you ask, <application>Privoxy</application> can co-exist 
 with other kinds of proxies like <application>Squid</application>.
</para>
</sect3>

<sect3>
<title id="firewall">What about as a firewall? Can <application>Privoxy</application> protect me?</title>
<para>
 Not in the way you mean, or in the way a true firewall can, or a proxy that
 has this specific capability. <application>Privoxy</application> can help
 protect your privacy, but not really protect you from intrusion attempts.
</para>
</sect3>


<sect3>
<title id="logo">The <application>Privoxy</application> logo that replaces ads is very blocky 
and ugly looking. Can't a better font be used?</title>

<para>
 This is not a font problem. The logo is an image that is created by 
 <application>Privoxy</application> on the fly. So as to not waste 
 memory, the image is rather small. The blockiness comes when the 
 image is scaled to fill a largish area. There is not much to be done 
 about this, other than to use one of the other
 <quote>imageblock</quote> directives: <emphasis>pattern</emphasis>, 
 <emphasis>blank</emphasis>, or a URL of your choosing.
</para>
<para>
Given the above problem, we have decided to remove the logo option entirely 
[as of v2.9.13].
</para>
</sect3>


<sect3>
<title id="wasted">I have large empty spaces now where ads used to be. 
Why?</title>
<para>
 It would be easy enough to just eliminate this space altogether, rather than
 fill it with blank space. But, this would create problems with many pages
 that use the overall size of the ad to help organize the page layout and
 position the various components of the page where they were intended to be.
 It is best left this way.
</para>

</sect3>

<sect3>
<title id="ssl">How can <application>Privoxy</application> filter Secure (HTTPS) URLs?</title>
<para>
 This is a limitation since HTTPS transactions are encrypted SSL sessions
 between your browser and the secure site, and are meant to be reliably 
 <emphasis>secure</emphasis> and private. This means that all cookies and HTTP
 header information are also encrypted from the time they leave your browser,
 to the site, and vice versa. <application>Privoxy</application> does not
 try to unencrypt this information, so it just passes through as is.
 <application>Privoxy</application> can still catch images and ads that
 are embedded in the SSL stream though.
</para>

</sect3>


<sect3>
<title id="secure"><application>Privoxy</application> runs as a <quote>server</quote>. How 
secure is it? Do I need to take any special precautions?</title>
<para>
 There are no known exploits that might effect
 <application>Privoxy</application>. 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> only listens to requests 
 from <quote>localhost</quote>. 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> config file. All LAN hosts can then use 
 this as their proxy address in the browser proxy configuration. In this way, 
 <application>Privoxy</application> will not listen on any external ports.
 Of course, a firewall is always good too. Better safe than sorry.
</para>

</sect3>

<sect3 id="turnoff">
<title>How can I temporarily disable <application>Privoxy</application>?</title>
<para>
 The easiest way is to access <application>Privoxy</application> with your 
 browser by using the special URL: <ulink url="http://p.p/">http://p.p/</ulink>
 and select "Toggle Privoxy on or off" from that page.

</para>
</sect3>

</sect2>


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

<sect2>
<title id="trouble">Troubleshooting</title>

<sect3>
<title id="refused">I just upgraded and am getting <quote>connection refused</quote>
with every web page?</title>
<para>
 Either <application>Privoxy</application> is not running, or your 
 browser is configured for a different port than what
 <application>Privoxy</application> is using.
</para>

<para>
 The old <application>Privoxy</application> (and also
 <application>Junkbuster</application>) used port 8000 by 
 default. This has been changed to port 8118 now, due to a conflict 
 with NAS (Network Audio Service), which uses port 8000. If you haven't, 
 you need to change your browser to the new port number, or alternately 
 change <application>Privoxy's</application> <quote>listen-address</quote>
 setting in the <filename>config</filename> file used to start 
 <application>Privoxy</application>.
</para>

</sect3>

<sect3>
<title id="flushit">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 in the picture. The best thing to do is try flushing 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://www.privoxy.org/config/show-url-info">http://www.privoxy.org/config/show-url-info</ulink>
 and see if any actions match your new rule.
</para>

</sect3>

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

<para>
 First verify that it is indeed a <application>Privoxy</application> problem, 
 by disabling <application>Privoxy</application> filtering and blocking. 
 Go to <ulink url="http://p.p/">http://p.p/</ulink> and click on 
 <quote>Toggle Privoxy On or Off</quote>, then disable it. Now try that 
 page again.
</para>

<para>
 If still a problem, go to <quote>Show which actions apply to a URL and
 why</quote> from <ulink url="http://p.p/">http://p.p/</ulink> and paste
 the full URL of the page in question into the prompt. See which actions are
 being applied to the URL. Now, armed with this information, go to <quote>Edit
 the actions list</quote>. Here you should see various sections that have
 various <application>Privoxy</application> features disabled for specific
 sites. Disabled <quote>actions</quote> will have a <quote>-</quote> (minus
 sign) in front of them. Add your problem page URL to one of these sections
 that looks like it is disabling the feature that is causing the
 problem. Re-try the page. There might be some trial and error involved. This
 is discussed in a little more detail in the 
 <ulink url="../user-manual/appendix.html#ACTIONSANAT">user-manual
 appendix</ulink>.

</para>

<para>
 Alternately, if you are comfortable with a text editor, you can accomplish 
 the same thing by editing the appropriate <quote>actions</quote> file.
</para>

</sect3>

<sect3 id="bugs">
<title>Where and how do I submit bug reports? Feature Requests? Etc?</title>
<para>
 Feedback is encouraged, whether good, bad or ugly. Please see the contact
 page in the <ulink url="../user-manual/contact.html">user-manual</ulink> for
 details.

</para>

</sect3>

<sect3>
<title id="time">What time is it?</title>
<para>
 Time for you to go!
</para>
</sect3>

</sect2>

</sect1>


<!--   ~~~~~       New section      ~~~~~     -->
<!--
FIXME: Commented out until we have something to put here. HB 03/18/02.
<sect1 id="knownissues"><title>Known Issues</title>
<para>
   Fillme.
</para>
</sect1>
-->

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

This is referenced in the doc header already. HB 03/25/02

<sect1 id="contact"><title>Contact the developers</title>
<para>Please see the user manual for information on how to contact the developers.
</para>
</sect1>
-->
<!--   ~~~~~       New section      ~~~~~     -->
<sect1 id="copyright"><title>Copyright and History</title>
<para>
 Please see the 
<ulink url="../user-manual/copyright.html#HISTORY">user-manual</ulink> for 
 information on Copyright and History.
</para>
</sect1>

<!--   ~~~~~       New section      ~~~~~     -->
<sect1 id="seealso"><title>See also</title>
<para>
 Please see the 
 <ulink url="../user-manual/seealso.html">user-manual</ulink> for 
 others references.
</para>
</sect1>

<!-- hhmts end -->
 <!--
 Tue 09/11/01 06:38:14 PM EST: Test SGML doc by Hal Burgiss.
 
 Last modified: Mon Sep 10 19:22:09 CEST 2001
 
 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., 59
 Temple Place - Suite 330, Boston, MA  02111-1307, USA.

$Log: faq.sgml,v $
Revision 1.32  2002/03/27 00:57:03  hal9
Touch ups for name change.

Revision 1.31  2002/03/26 22:29:55  swa
we have a new homepage!

Revision 1.30  2002/03/25 16:39:22  hal9
A few new sections. Made all links relative to user-manual.

Revision 1.29  2002/03/25 05:23:57  hal9
Moved section, and touch ups.

Revision 1.28  2002/03/25 04:27:33  hal9
New section related to name change.

Revision 1.25  2002/03/24 16:08:08  swa
we are too lazy to make a block-built
privoxy logo. hence removed the option.

Revision 1.24  2002/03/24 15:46:20  swa
name change related issue.

Revision 1.23  2002/03/24 12:33:01  swa
more additions.

Revision 1.22  2002/03/24 11:51:00  swa
name change. changed filenames.

Revision 1.21  2002/03/24 11:01:06  swa
name change

Revision 1.20  2002/03/23 15:13:11  swa
renamed every reference to the old name with foobar.
fixed "application foobar application" tag, fixed
"the foobar" with "foobar". left junkbustser in cvs
comments and remarks to history untouched.

Revision 1.19  2002/03/21 17:01:54  hal9
Some touch ups.

Revision 1.18  2002/03/18 16:40:31  hal9
More additions.

Revision 1.17  2002/03/18 03:53:53  hal9
Some new additions.

Revision 1.16  2002/03/17 21:32:56  hal9
A few more additions.

Revision 1.15  2002/03/17 07:25:59  hal9
Correcting some of my typos, and some additions.

Revision 1.14  2002/03/17 02:39:13  hal9
A little more added ...

Revision 1.13  2002/03/17 00:22:20  hal9
Adding new stuff, and trying to incorporate stuff from old faq.

Revision 1.12  2002/03/11 20:13:21  swa
typo

Revision 1.11  2002/03/11 18:42:27  swa
new section

Revision 1.10  2002/03/11 13:13:27  swa
correct feedback channels

Revision 1.9  2002/03/10 23:34:04  swa
more info on not hiding ip address

Revision 1.8  2002/03/09 15:55:48  swa
added default config section

Revision 1.7  2002/03/07 18:16:55  swa
looks better

Revision 1.6  2002/03/07 13:16:31  oes
Committing changes by Stefan

Revision 1.5  2002/03/02 15:50:04  swa
2.9.11 version. more input for docs.

Revision 1.4  2002/02/24 14:34:24  jongfoster
Formatting changes.  Now changing the doctype to DocBook XML 4.1
will work - no other changes are needed.

Revision 1.3  2001/09/23 10:13:48  swa
upload process established. run make webserver and
the documentation is moved to the webserver. documents
are now linked correctly.

Revision 1.2  2001/09/13 15:20:17  swa
merged standards into developer manual

Revision 1.1  2001/09/12 15:36:41  swa
source files for junkbuster documentation

Revision 1.3  2001/09/10 17:43:59  swa
first proposal of a structure.

Revision 1.2  2001/06/13 14:28:31  swa
docs should have an author.

Revision 1.1  2001/06/13 14:20:37  swa
first import of project's documentation for the webserver.

-->

</article>