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updated privoxy to 3.0.19-stable
2012-06-28 03:17:49 +00:00
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<meta name="generator" content=
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<title>General Information</title>
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<body class="SECT1">
<div class="NAVHEADER">
<table summary="Header navigation table" width="100%" border="0"
cellpadding="0" cellspacing="0">
<tr>
<th colspan="3" align="center">Privoxy Frequently Asked
Questions</th>
</tr>
<tr>
<td width="10%" align="left" valign="bottom"><a href="index.html"
accesskey="P">Prev</a></td>
<td width="80%" align="center" valign="bottom"></td>
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<div class="SECT1">
<h1 class="SECT1"><a name="GENERAL" id="GENERAL">1. General
Information</a></h1>
<div class="SECT2">
<h3 class="SECT2"><a name="WHO-USES" id="WHO-USES">1.1. Who should give
<span class="APPLICATION">Privoxy</span> a try?</a></h3>
<p>Anyone who is interested in security, privacy, or in finer-grained
control over their web and Internet experience.</p>
</div>
<div class="SECT2">
<h3 class="SECT2"><a name="BESTCHOICE" id="BESTCHOICE">1.2. Is Privoxy
the best choice for me?</a></h3>
<p><span class="APPLICATION">Privoxy</span> 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.</p>
<p>One of <span class="APPLICATION">Privoxy's</span> 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 <a href=
"http://en.wikipedia.org/wiki/Http" target="_top">HTTP</a> and other
networking protocols, <a href="http://en.wikipedia.org/wiki/Html"
target="_top">HTML</a>, and <a href=
"http://en.wikipedia.org/wiki/Regular_expressions" target=
"_top"><span class="QUOTE">"Regular Expressions"</span></a> will be a
big plus and will help you get the most out of <span class=
"APPLICATION">Privoxy</span>. 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.</p>
<p>Much of <span class="APPLICATION">Privoxy's</span> configuration can
be done with a <a href="http://en.wikipedia.org/wiki/Web_browser"
target="_top">Web browser</a>. But there are areas where configuration
is done using a <a href="http://en.wikipedia.org/wiki/Text_editors"
target="_top">text editor</a> 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
<span class="APPLICATION">Privoxy</span> listening port can be
trusted.</p>
</div>
<div class="SECT2">
<h3 class="SECT2"><a name="PROXYMORON" id="PROXYMORON">1.3. What is a
<span class="QUOTE">"proxy"</span>? How does Privoxy work?</a></h3>
<p>A <a href="http://en.wikipedia.org/wiki/Proxy_server" target=
"_top">web proxy</a> is a service, based on a software such as
<span class="APPLICATION">Privoxy</span>, 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
<span class="QUOTE">"go-between"</span>. For details, see <a href=
"http://en.wikipedia.org/wiki/Proxy_server" target="_top">Wikipedia's
proxy definition</a>.</p>
<p>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.</p>
<p><span class="APPLICATION">Privoxy</span> 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.</p>
</div>
<div class="SECT2">
<h3 class="SECT2"><a name="OTHERSTUFF" id="OTHERSTUFF">1.4. Does
Privoxy do anything more than ad blocking?</a></h3>
<p>Yes, ad blocking is but one possible use. There are many, many ways
<span class="APPLICATION">Privoxy</span> can be used to sanitize and
customize web browsing.</p>
</div>
<div class="SECT2">
<h3 class="SECT2"><a name="NEWJB" id="NEWJB">1.5. What is this new
version of <span class="QUOTE">"Junkbuster"</span>?</a></h3>
<p>A long time ago, there was the <a href=
"http://www.junkbusters.com/ijb.html" target="_top"><span class=
"APPLICATION">Internet Junkbuster</span></a>, by Anonymous Coders and
<a href="http://www.junkbusters.com/" target="_top">Junkbusters
Corporation</a>. This saved many users a lot of pain in the early days
of web advertising and user tracking.</p>
<p>But the web, its protocols and standards, and with it, the
techniques for forcing ads on users, give up autonomy over their
browsing, and for tracking them, keeps evolving. Unfortunately, the
<span class="APPLICATION">Internet Junkbuster</span> did not. Version
2.0.2, published in 1998, was (and is) the last official <a href=
"http://www.junkbusters.com/ijbdist.html#release" target=
"_top">release</a> available from <a href="http://www.junkbusters.com"
target="_top">Junkbusters Corporation</a>. Fortunately, it had been
released under the GNU <a href=
"http://www.gnu.org/licenses/old-licenses/gpl-2.0.html" target=
"_top">GPL</a>, which allowed further development by others.</p>
<p>So Stefan Waldherr started maintaining an improved version of the
software, to which eventually a number of people contributed patches.
It could already replace banners with a transparent image, and had a
first version of pop-up killing, but it was still very closely based on
the original, with all its limitations, such as the lack of HTTP/1.1
support, flexible per-site configuration, or content modification. The
last release from this effort was version 2.0.2-10, published in
2000.</p>
<p>Then, some <a href=
"http://www.privoxy.org/user-manual/copyright.html#AUTHORS" target=
"_top">developers</a> picked up the thread, and started turning the
software inside out, upside down, and then reassembled it, adding many
<a href="http://www.privoxy.org/user-manual/introduction.html#FEATURES"
target="_top">new features</a> along the way.</p>
<p>The result of this is <span class="APPLICATION">Privoxy</span>,
whose first stable version, 3.0, was released August, 2002.</p>
</div>
<div class="SECT2">
<h3 class="SECT2"><a name="AEN85" id="AEN85">1.6. Why <span class=
"QUOTE">"Privoxy"</span>? Why change the name from Junkbuster at
all?</a></h3>
<p>Though outdated, <a href="http://junkbusters.com/" target=
"_top">Junkbusters Corporation</a> continues to offer their original
version of the <span class="APPLICATION">Internet Junkbuster</span>, so
publishing our <span class="APPLICATION">Junkbuster</span>-derived
software under the same name led to confusion.</p>
<p>There are also potential legal complications from our use of the
<span class="APPLICATION">Junkbuster</span> name, which is a registered
trademark of <a href="http://junkbusters.com/" target=
"_top">Junkbusters Corporation</a>. There are, however, no objections
from Junkbusters Corporation to the <span class=
"APPLICATION">Privoxy</span> project itself, and they, in fact, still
share our ideals and goals.</p>
<p>The developers also believed that there are 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.</p>
<p><span class="APPLICATION">Privoxy</span> is the <span class=
"QUOTE">"<span class="emphasis EMPHASIS c2">Privacy Enhancing
Proxy</span>"</span>. Also, its content modification and junk
suppression gives <span class="emphasis EMPHASIS c2">you</span>, the
user, more control, more freedom, and allows you to browse your
personal and <span class="QUOTE">"<span class=
"emphasis EMPHASIS c2">private</span> edition"</span> of the web.</p>
</div>
<div class="SECT2">
<h3 class="SECT2"><a name="DIFFERS" id="DIFFERS">1.7. How does Privoxy
differ from the old Junkbuster?</a></h3>
<p><span class="APPLICATION">Privoxy</span> picks up where <span class=
"APPLICATION">Junkbuster</span> left off. The new <span class=
"APPLICATION">Privoxy</span> still blocks ads and banners, still
manages <a href="http://en.wikipedia.org/wiki/Browser_cookie" target=
"_top">cookies</a>, 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.</p>
<p><span class="APPLICATION">Privoxy</span>'s new features include:</p>
<ul>
<li>
<p>Supports "Connection: keep-alive". Outgoing connections can be
kept alive independently from the client.</p>
</li>
<li>
<p>Supports IPv6, provided the operating system does so too, and
the configure script detects it.</p>
</li>
<li>
<p>Supports tagging which allows to change the behaviour based on
client and server headers.</p>
</li>
<li>
<p>Can be run as an "intercepting" proxy, which obviates the need
to configure browsers individually.</p>
</li>
<li>
<p>Sophisticated actions and filters for manipulating both server
and client headers.</p>
</li>
<li>
<p>Can be chained with other proxies.</p>
</li>
<li>
<p>Integrated browser-based configuration and control utility at
<a href="http://config.privoxy.org/" target=
"_top">http://config.privoxy.org/</a> (shortcut: <a href=
"http://p.p/" target="_top">http://p.p/</a>). Browser-based tracing
of rule and filter effects. Remote toggling.</p>
</li>
<li>
<p>Web page filtering (text replacements, removes banners based on
size, invisible <span class="QUOTE">"web-bugs"</span> and HTML
annoyances, etc.)</p>
</li>
<li>
<p>Modularized configuration that allows for standard settings and
user settings to reside in separate files, so that installing
updated actions files won't overwrite individual user settings.</p>
</li>
<li>
<p>Support for Perl Compatible Regular Expressions in the
configuration files, and a more sophisticated and flexible
configuration syntax.</p>
</li>
<li>
<p>GIF de-animation.</p>
</li>
<li>
<p>Bypass many click-tracking scripts (avoids script
redirection).</p>
</li>
<li>
<p>User-customizable HTML templates for most proxy-generated pages
(e.g. "blocked" page).</p>
</li>
<li>
<p>Auto-detection and re-reading of config file changes.</p>
</li>
<li>
<p>Most features are controllable on a per-site or per-location
basis.</p>
</li>
<li>
<p>Many smaller new features added, limitations and bugs
removed.</p>
</li>
</ul>
</div>
<div class="SECT2">
<h3 class="SECT2"><a name="WHATSANAD" id="WHATSANAD">1.8. How does
Privoxy know what is an ad, and what is not?</a></h3>
<p><span class="APPLICATION">Privoxy</span>'s approach to blocking ads
is twofold:</p>
<p>First, there are certain patterns in the <span class=
"emphasis EMPHASIS c2">locations</span> (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 <span class=
"QUOTE">"banners"</span>!) and the host (blocking the big banner
hosting services like doublecklick.net already helps a lot).
<span class="APPLICATION">Privoxy</span> takes advantage of this fact
by using <a href="../user-manual/actions-file.html#AF-PATTERNS" target=
"_top">URL patterns</a> to sort out and block the requests for things
that sound like they would be ads or banners.</p>
<p>Second, banners tend to come in certain <span class=
"emphasis EMPHASIS c2">sizes</span>. 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, <span class="APPLICATION">Privoxy</span>
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.</p>
<p>Both of this involves a certain amount of guesswork and is, of
course, freely and readily configurable.</p>
</div>
<div class="SECT2">
<h3 class="SECT2"><a name="AEN163" id="AEN163">1.9. Can Privoxy make
mistakes? This does not sound very scientific.</a></h3>
<p>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.</p>
<p>But this should not be a big concern since the <span class=
"APPLICATION">Privoxy</span> 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.
(<a href="trouble.html#BADSITE">See the Troubleshooting section
below</a>.)</p>
</div>
<div class="SECT2">
<h3 class="SECT2"><a name="AEN169" id="AEN169">1.10. Will I have to
configure Privoxy before I can use it?</a></h3>
<p>That depends on your expectations. The default installation should
give you a good starting point, and block <span class=
"emphasis EMPHASIS c2">most</span> ads and unwanted content, but many
of the more advanced features are off by default, and require you to
activate them.</p>
<p>You do have to set up your browser to use <span class=
"APPLICATION">Privoxy</span> (see the <a href=
"installation.html#FIRSTSTEP">Installation section below</a>).</p>
<p>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 <span class=
"APPLICATION">Privoxy's</span> configuration to more closely match your
individual situation. And we encourage you to do this. This is where
the real power of <span class="APPLICATION">Privoxy</span> lies!</p>
</div>
<div class="SECT2">
<h3 class="SECT2"><a name="LAN" id="LAN">1.11. Can Privoxy run as a
server on a network?</a></h3>
<p>Yes, <span class="APPLICATION">Privoxy</span> runs as a server
already, and can easily be configured to <span class=
"QUOTE">"serve"</span> more than one client. See <a href=
"configuration.html#LANCONFIG">How can I set up Privoxy to act as a
proxy for my LAN</a> below.</p>
</div>
<div class="SECT2">
<h3 class="SECT2"><a name="BROWSERS2" id="BROWSERS2">1.12. My browser
does the same things as Privoxy. Why should I use Privoxy at
all?</a></h3>
<p>Modern browsers do indeed have <span class=
"emphasis EMPHASIS c2">some</span> of the same functionality as
<span class="APPLICATION">Privoxy</span>. Maybe this is adequate for
you. But <span class="APPLICATION">Privoxy</span> is very versatile and
powerful, and can probably do a number of things your browser just
can't.</p>
<p>In addition, a proxy is good choice if you use multiple browsers, or
have a LAN with multiple computers since <span class=
"APPLICATION">Privoxy</span> 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.</p>
<p>Note, however, that it's recommended to leverage both your browser's
and <span class="APPLICATION">Privoxy's</span> privacy enhancing
features at the same time. While your browser probably lacks some
features <span class="APPLICATION">Privoxy</span> offers, it should
also be able to do some things more reliable, for example restricting
and suppressing JavaScript.</p>
</div>
<div class="SECT2">
<h3 class="SECT2"><a name="WHYTRUST" id="WHYTRUST">1.13. Why should I
trust Privoxy?</a></h3>
<p>The most important reason is because you have access to <span class=
"emphasis EMPHASIS c2">everything</span>, 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 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 <span class="emphasis EMPHASIS c2">yours</span>.
In fact, we encourage this level of scrutiny. It is one reason we use
<span class="APPLICATION">Privoxy</span> ourselves.</p>
</div>
<div class="SECT2">
<h3 class="SECT2"><a name="LICENSE" id="LICENSE">1.14. Is there is a
license or fee? What about a warranty? Registration?</a></h3>
<p><span class="APPLICATION">Privoxy</span> is free software and
licensed under the <a href=
"http://www.gnu.org/licenses/old-licenses/gpl-2.0.html" target=
"_top">GNU General Public License (GPL) version 2</a>. It is free to
use, copy, modify or distribute as you wish under the terms of this
license. Please see the <a href="copyright.html">Copyright</a> section
for more information on the license and copyright. Or the <tt class=
"FILENAME">LICENSE</tt> file that should be included.</p>
<p>There is <span class="emphasis EMPHASIS c2">no warranty</span> of
any kind, expressed, implied or otherwise. That is something that would
cost real money ;-) There is no registration either.</p>
</div>
<div class="SECT2">
<h3 class="SECT2"><a name="SPYWARE" id="SPYWARE">1.15. Can Privoxy
remove spyware? Adware? Viruses?</a></h3>
<p>No, at least not reliably enough to trust it. <span class=
"APPLICATION">Privoxy</span> is not designed to be a malware removal
tool and the default configuration doesn't even try to filter out any
malware.</p>
<p><span class="APPLICATION">Privoxy</span> 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.</p>
</div>
<div class="SECT2">
<h3 class="SECT2"><a name="OTHERADS" id="OTHERADS">1.16. Can I use
Privoxy with other ad-blocking software?</a></h3>
<p><span class="APPLICATION">Privoxy</span> should work fine with other
proxies and other software in general.</p>
<p>But it is probably not necessary to use <span class=
"APPLICATION">Privoxy</span> 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.</p>
<p>Note that this is an advice specific to ad blocking.</p>
</div>
<div class="SECT2">
<h3 class="SECT2"><a name="HELP-THE-DEVELOPERS" id=
"HELP-THE-DEVELOPERS">1.17. I would like to help you, what can I
do?</a></h3>
<div class="SECT3">
<h4 class="SECT3"><a name="PARTICIPATE" id="PARTICIPATE">1.17.1.
Would you like to participate?</a></h4>
<p>Well, we <span class="emphasis EMPHASIS c2">always</span> 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 <span class=
"emphasis EMPHASIS c2">DO NOT</span> need to be a <span class=
"QUOTE">"programmer"</span>. 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.</p>
<p>So first thing, subscribe to the <a href=
"https://lists.sourceforge.net/lists/listinfo/ijbswa-users" target=
"_top">Privoxy Users</a> or the <a href=
"https://lists.sourceforge.net/lists/listinfo/ijbswa-developers"
target="_top">Privoxy Developers</a> mailing list, join the
discussion, help out other users, provide general feedback or report
problems you noticed.</p>
<p>If you intend to help out with the trackers, you also might want
to <a href="https://sourceforge.net/account/register.php" target=
"_top">get an account on SourceForge.net</a> so we don't confuse you
with the other name-less users.</p>
<p>We also have a <a href="../developer-manual/index.html" target=
"_top">Developer's Manual</a>. While it is partly out of date, it's
still worth reading.</p>
<p>Our <a href=
"http://ijbswa.cvs.sourceforge.net/viewvc/ijbswa/current/TODO?view=markup"
target="_top">TODO list</a> may be of interest to you as well. Please
let us know if you want to work on one of the items listed.</p>
</div>
<div class="SECT3">
<h4 class="SECT3"><a name="DONATE" id="DONATE">1.17.2. Would you like
to donate?</a></h4>
<p><span class="APPLICATION">Privoxy</span> is developed by unpaid
volunteers and thus our current running costs are pretty low.
Nevertheless, we have plans that will cost money in the future. They
include, but aren't limited to spending money on:</p>
<ul>
<li>
<p>Hardware to help make sure <span class=
"APPLICATION">Privoxy</span> keeps running on platforms the
developers currently can't test on and can be ported to
others.</p>
</li>
<li>
<p>Technical books to educate our developers about said platforms
or to improve their knowledge in general.</p>
</li>
<li>
<p>More reliable hosting,</p>
</li>
</ul>
<p>We would like to get this money through donations made by our
users.</p>
<p><span class="APPLICATION">Privoxy</span> has therefore become an
associated project of <a href=
"http://www.spi-inc.org/about-spi/about-spi" target="_top">Software
in the Public Interest (SPI)</a>, which allows us to receive
donations. In the United States they are tax-deductible, in a few
other western countries they might be tax-deductible in the
future.</p>
<p>If you read this section before you may notice that paying for the
project domain privoxy.org is no longer on the list. It has been
transferred to SPI is sponsored by Mythic Beasts Ltd.</p>
<p>If you enjoy our software and feel like helping out with a
donation, please have a look at <a href=
"http://www.spi-inc.org/donations" target="_top">SPI's donation
page</a> to see what the options are. If you have any questions
regarding donations please mail to either the public user mailing
list or, if it's a private matter, to <a href=
"mailto:fk@fabiankeil.de" target="_top">Fabian Keil</a> (Privoxy's
SPI liason) directly.</p>
</div>
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