1 <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"
2 "http://www.w3.org/TR/html4/loose.dtd">
6 <meta name="generator" content=
7 "HTML Tidy for Linux/x86 (vers 7 December 2008), see www.w3.org">
9 <title>General Information</title>
10 <meta name="GENERATOR" content=
11 "Modular DocBook HTML Stylesheet Version 1.79">
12 <link rel="HOME" title="Privoxy Frequently Asked Questions" href=
14 <link rel="PREVIOUS" title="Privoxy Frequently Asked Questions" href=
16 <link rel="NEXT" title="Installation" href="installation.html">
17 <link rel="STYLESHEET" type="text/css" href="../p_doc.css">
18 <meta http-equiv="Content-Type" content="text/html; charset=us-ascii">
19 <style type="text/css">
21 background-color: #EEEEEE;
24 :link { color: #0000FF }
25 :visited { color: #840084 }
26 :active { color: #0000FF }
27 span.c2 {font-style: italic}
28 hr.c1 {text-align: left}
33 <div class="NAVHEADER">
34 <table summary="Header navigation table" width="100%" border="0"
35 cellpadding="0" cellspacing="0">
37 <th colspan="3" align="center">Privoxy Frequently Asked
42 <td width="10%" align="left" valign="bottom"><a href="index.html"
43 accesskey="P">Prev</a></td>
45 <td width="80%" align="center" valign="bottom"></td>
47 <td width="10%" align="right" valign="bottom"><a href=
48 "installation.html" accesskey="N">Next</a></td>
51 <hr class="c1" width="100%">
55 <h1 class="SECT1"><a name="GENERAL" id="GENERAL">1. General
59 <h3 class="SECT2"><a name="WHO-USES" id="WHO-USES">1.1. Who should give
60 <span class="APPLICATION">Privoxy</span> a try?</a></h3>
62 <p>Anyone who is interested in security, privacy, or in finer-grained
63 control over their web and Internet experience.</p>
67 <h3 class="SECT2"><a name="BESTCHOICE" id="BESTCHOICE">1.2. Is Privoxy
68 the best choice for me?</a></h3>
70 <p><span class="APPLICATION">Privoxy</span> is certainly a good choice,
71 especially for those who want more control and security. Those with the
72 willingness to read the documentation and the ability to fine-tune
73 their installation will benefit the most.</p>
75 <p>One of <span class="APPLICATION">Privoxy's</span> strengths is that
76 it is highly configurable giving you the ability to completely
77 personalize your installation. Being familiar with, or at least having
78 an interest in learning about <a href=
79 "http://en.wikipedia.org/wiki/Http" target="_top">HTTP</a> and other
80 networking protocols, <a href="http://en.wikipedia.org/wiki/Html"
81 target="_top">HTML</a>, and <a href=
82 "http://en.wikipedia.org/wiki/Regular_expressions" target=
83 "_top"><span class="QUOTE">"Regular Expressions"</span></a> will be a
84 big plus and will help you get the most out of <span class=
85 "APPLICATION">Privoxy</span>. A new installation just includes a very
86 basic configuration. The user should take this as a starting point
87 only, and enhance it as he or she sees fit. In fact, the user is
88 encouraged, and expected to, fine-tune the configuration.</p>
90 <p>Much of <span class="APPLICATION">Privoxy's</span> configuration can
91 be done with a <a href="http://en.wikipedia.org/wiki/Web_browser"
92 target="_top">Web browser</a>. But there are areas where configuration
93 is done using a <a href="http://en.wikipedia.org/wiki/Text_editors"
94 target="_top">text editor</a> to edit configuration files. Also note
95 that the web-based action editor doesn't use authentication and should
96 only be enabled in environments where all clients with access to
97 <span class="APPLICATION">Privoxy</span> listening port can be
102 <h3 class="SECT2"><a name="PROXYMORON" id="PROXYMORON">1.3. What is a
103 <span class="QUOTE">"proxy"</span>? How does Privoxy work?</a></h3>
105 <p>A <a href="http://en.wikipedia.org/wiki/Proxy_server" target=
106 "_top">web proxy</a> is a service, based on a software such as
107 <span class="APPLICATION">Privoxy</span>, that clients (i.e. browsers)
108 can use instead of connecting to web servers directly. The clients then
109 ask the proxy to request objects (web pages, images, movies etc) on
110 their behalf and to forward the data to the clients. It is a
111 <span class="QUOTE">"go-between"</span>. For details, see <a href=
112 "http://en.wikipedia.org/wiki/Proxy_server" target="_top">Wikipedia's
113 proxy definition</a>.</p>
115 <p>There are many reasons to use web proxies, such as security
116 (firewalling), efficiency (caching) and others, and there are any
117 number of proxies to accommodate those needs.</p>
119 <p><span class="APPLICATION">Privoxy</span> is a proxy that is
120 primarily focused on privacy enhancement, ad and junk elimination and
121 freeing the user from restrictions placed on his activities. Sitting
122 between your browser(s) and the Internet, it is in a perfect position
123 to filter outbound personal information that your browser is leaking,
124 as well as inbound junk. It uses a variety of techniques to do this,
125 all of which are under your complete control via the various
126 configuration files and options. Being a proxy also makes it easier to
127 share configurations among multiple browsers and/or users.</p>
131 <h3 class="SECT2"><a name="OTHERSTUFF" id="OTHERSTUFF">1.4. Does
132 Privoxy do anything more than ad blocking?</a></h3>
134 <p>Yes, ad blocking is but one possible use. There are many, many ways
135 <span class="APPLICATION">Privoxy</span> can be used to sanitize and
136 customize web browsing.</p>
140 <h3 class="SECT2"><a name="NEWJB" id="NEWJB">1.5. What is this new
141 version of <span class="QUOTE">"Junkbuster"</span>?</a></h3>
143 <p>A long time ago, there was the <a href=
144 "http://www.junkbusters.com/ijb.html" target="_top"><span class=
145 "APPLICATION">Internet Junkbuster</span></a>, by Anonymous Coders and
146 <a href="http://www.junkbusters.com/" target="_top">Junkbusters
147 Corporation</a>. This saved many users a lot of pain in the early days
148 of web advertising and user tracking.</p>
150 <p>But the web, its protocols and standards, and with it, the
151 techniques for forcing ads on users, give up autonomy over their
152 browsing, and for tracking them, keeps evolving. Unfortunately, the
153 <span class="APPLICATION">Internet Junkbuster</span> did not. Version
154 2.0.2, published in 1998, was (and is) the last official <a href=
155 "http://www.junkbusters.com/ijbdist.html#release" target=
156 "_top">release</a> available from <a href="http://www.junkbusters.com"
157 target="_top">Junkbusters Corporation</a>. Fortunately, it had been
158 released under the GNU <a href=
159 "http://www.gnu.org/licenses/old-licenses/gpl-2.0.html" target=
160 "_top">GPL</a>, which allowed further development by others.</p>
162 <p>So Stefan Waldherr started maintaining an improved version of the
163 software, to which eventually a number of people contributed patches.
164 It could already replace banners with a transparent image, and had a
165 first version of pop-up killing, but it was still very closely based on
166 the original, with all its limitations, such as the lack of HTTP/1.1
167 support, flexible per-site configuration, or content modification. The
168 last release from this effort was version 2.0.2-10, published in
171 <p>Then, some <a href=
172 "http://www.privoxy.org/user-manual/copyright.html#AUTHORS" target=
173 "_top">developers</a> picked up the thread, and started turning the
174 software inside out, upside down, and then reassembled it, adding many
175 <a href="http://www.privoxy.org/user-manual/introduction.html#FEATURES"
176 target="_top">new features</a> along the way.</p>
178 <p>The result of this is <span class="APPLICATION">Privoxy</span>,
179 whose first stable version, 3.0, was released August, 2002.</p>
183 <h3 class="SECT2"><a name="AEN85" id="AEN85">1.6. Why <span class=
184 "QUOTE">"Privoxy"</span>? Why change the name from Junkbuster at
187 <p>Though outdated, <a href="http://junkbusters.com/" target=
188 "_top">Junkbusters Corporation</a> continues to offer their original
189 version of the <span class="APPLICATION">Internet Junkbuster</span>, so
190 publishing our <span class="APPLICATION">Junkbuster</span>-derived
191 software under the same name led to confusion.</p>
193 <p>There are also potential legal complications from our use of the
194 <span class="APPLICATION">Junkbuster</span> name, which is a registered
195 trademark of <a href="http://junkbusters.com/" target=
196 "_top">Junkbusters Corporation</a>. There are, however, no objections
197 from Junkbusters Corporation to the <span class=
198 "APPLICATION">Privoxy</span> project itself, and they, in fact, still
199 share our ideals and goals.</p>
201 <p>The developers also believed that there are so many improvements
202 over the original code, that it was time to make a clean break from the
203 past and make a name in their own right.</p>
205 <p><span class="APPLICATION">Privoxy</span> is the <span class=
206 "QUOTE">"<span class="emphasis EMPHASIS c2">Privacy Enhancing
207 Proxy</span>"</span>. Also, its content modification and junk
208 suppression gives <span class="emphasis EMPHASIS c2">you</span>, the
209 user, more control, more freedom, and allows you to browse your
210 personal and <span class="QUOTE">"<span class=
211 "emphasis EMPHASIS c2">private</span> edition"</span> of the web.</p>
215 <h3 class="SECT2"><a name="DIFFERS" id="DIFFERS">1.7. How does Privoxy
216 differ from the old Junkbuster?</a></h3>
218 <p><span class="APPLICATION">Privoxy</span> picks up where <span class=
219 "APPLICATION">Junkbuster</span> left off. The new <span class=
220 "APPLICATION">Privoxy</span> still blocks ads and banners, still
221 manages <a href="http://en.wikipedia.org/wiki/Browser_cookie" target=
222 "_top">cookies</a>, and still helps protect your privacy. But, most of
223 these features have been enhanced, and many new ones have been added,
224 all in the same vein.</p>
226 <p><span class="APPLICATION">Privoxy</span>'s new features include:</p>
230 <p>Supports "Connection: keep-alive". Outgoing connections can be
231 kept alive independently from the client.</p>
235 <p>Supports IPv6, provided the operating system does so too, and
236 the configure script detects it.</p>
240 <p>Supports tagging which allows to change the behaviour based on
241 client and server headers.</p>
245 <p>Can be run as an "intercepting" proxy, which obviates the need
246 to configure browsers individually.</p>
250 <p>Sophisticated actions and filters for manipulating both server
251 and client headers.</p>
255 <p>Can be chained with other proxies.</p>
259 <p>Integrated browser-based configuration and control utility at
260 <a href="http://config.privoxy.org/" target=
261 "_top">http://config.privoxy.org/</a> (shortcut: <a href=
262 "http://p.p/" target="_top">http://p.p/</a>). Browser-based tracing
263 of rule and filter effects. Remote toggling.</p>
267 <p>Web page filtering (text replacements, removes banners based on
268 size, invisible <span class="QUOTE">"web-bugs"</span> and HTML
269 annoyances, etc.)</p>
273 <p>Modularized configuration that allows for standard settings and
274 user settings to reside in separate files, so that installing
275 updated actions files won't overwrite individual user settings.</p>
279 <p>Support for Perl Compatible Regular Expressions in the
280 configuration files, and a more sophisticated and flexible
281 configuration syntax.</p>
285 <p>GIF de-animation.</p>
289 <p>Bypass many click-tracking scripts (avoids script
294 <p>User-customizable HTML templates for most proxy-generated pages
295 (e.g. "blocked" page).</p>
299 <p>Auto-detection and re-reading of config file changes.</p>
303 <p>Most features are controllable on a per-site or per-location
308 <p>Many smaller new features added, limitations and bugs
315 <h3 class="SECT2"><a name="WHATSANAD" id="WHATSANAD">1.8. How does
316 Privoxy know what is an ad, and what is not?</a></h3>
318 <p><span class="APPLICATION">Privoxy</span>'s approach to blocking ads
321 <p>First, there are certain patterns in the <span class=
322 "emphasis EMPHASIS c2">locations</span> (URLs) of banner images. This
323 applies to both the path (you wouldn't guess how many web sites serve
324 their banners from a directory called <span class=
325 "QUOTE">"banners"</span>!) and the host (blocking the big banner
326 hosting services like doublecklick.net already helps a lot).
327 <span class="APPLICATION">Privoxy</span> takes advantage of this fact
328 by using <a href="../user-manual/actions-file.html#AF-PATTERNS" target=
329 "_top">URL patterns</a> to sort out and block the requests for things
330 that sound like they would be ads or banners.</p>
332 <p>Second, banners tend to come in certain <span class=
333 "emphasis EMPHASIS c2">sizes</span>. But you can't tell the size of an
334 image by its URL without downloading it, and if you do, it's too late
335 to save bandwidth. Therefore, <span class="APPLICATION">Privoxy</span>
336 also inspects the HTML sources of web pages while they are loaded, and
337 replaces references to images with standard banner sizes by dummy
338 references, so that your browser doesn't request them anymore in the
341 <p>Both of this involves a certain amount of guesswork and is, of
342 course, freely and readily configurable.</p>
346 <h3 class="SECT2"><a name="AEN163" id="AEN163">1.9. Can Privoxy make
347 mistakes? This does not sound very scientific.</a></h3>
349 <p>Actually, it's a black art ;-) And yes, it is always possible to
350 have a broad rule accidentally block or change something by mistake.
351 You will almost surely run into such situations at some point. It is
352 tricky writing rules to cover every conceivable possibility, and not
353 occasionally get false positives.</p>
355 <p>But this should not be a big concern since the <span class=
356 "APPLICATION">Privoxy</span> configuration is very flexible, and
357 includes tools to help identify these types of situations so they can
358 be addressed as needed, allowing you to customize your installation.
359 (<a href="trouble.html#BADSITE">See the Troubleshooting section
364 <h3 class="SECT2"><a name="AEN169" id="AEN169">1.10. Will I have to
365 configure Privoxy before I can use it?</a></h3>
367 <p>That depends on your expectations. The default installation should
368 give you a good starting point, and block <span class=
369 "emphasis EMPHASIS c2">most</span> ads and unwanted content, but many
370 of the more advanced features are off by default, and require you to
373 <p>You do have to set up your browser to use <span class=
374 "APPLICATION">Privoxy</span> (see the <a href=
375 "installation.html#FIRSTSTEP">Installation section below</a>).</p>
377 <p>And you will certainly run into situations where there are false
378 positives, or ads not being blocked that you may not want to see. In
379 these cases, you would certainly benefit by customizing <span class=
380 "APPLICATION">Privoxy's</span> configuration to more closely match your
381 individual situation. And we encourage you to do this. This is where
382 the real power of <span class="APPLICATION">Privoxy</span> lies!</p>
386 <h3 class="SECT2"><a name="LAN" id="LAN">1.11. Can Privoxy run as a
387 server on a network?</a></h3>
389 <p>Yes, <span class="APPLICATION">Privoxy</span> runs as a server
390 already, and can easily be configured to <span class=
391 "QUOTE">"serve"</span> more than one client. See <a href=
392 "configuration.html#LANCONFIG">How can I set up Privoxy to act as a
393 proxy for my LAN</a> below.</p>
397 <h3 class="SECT2"><a name="BROWSERS2" id="BROWSERS2">1.12. My browser
398 does the same things as Privoxy. Why should I use Privoxy at
401 <p>Modern browsers do indeed have <span class=
402 "emphasis EMPHASIS c2">some</span> of the same functionality as
403 <span class="APPLICATION">Privoxy</span>. Maybe this is adequate for
404 you. But <span class="APPLICATION">Privoxy</span> is very versatile and
405 powerful, and can probably do a number of things your browser just
408 <p>In addition, a proxy is good choice if you use multiple browsers, or
409 have a LAN with multiple computers since <span class=
410 "APPLICATION">Privoxy</span> can run as a server application. This way
411 all the configuration is in one place, and you don't have to maintain a
412 similar configuration for possibly many browsers or users.</p>
414 <p>Note, however, that it's recommended to leverage both your browser's
415 and <span class="APPLICATION">Privoxy's</span> privacy enhancing
416 features at the same time. While your browser probably lacks some
417 features <span class="APPLICATION">Privoxy</span> offers, it should
418 also be able to do some things more reliable, for example restricting
419 and suppressing JavaScript.</p>
423 <h3 class="SECT2"><a name="WHYTRUST" id="WHYTRUST">1.13. Why should I
424 trust Privoxy?</a></h3>
426 <p>The most important reason is because you have access to <span class=
427 "emphasis EMPHASIS c2">everything</span>, and you can control
428 everything. You can check every line of every configuration file
429 yourself. You can check every last bit of source code should you
430 desire. And even if you can't read code, there should be some comfort
431 in knowing that other people can, and do read it. You can build the
432 software from scratch, if you want, so that you know the executable is
433 clean, and that it is <span class="emphasis EMPHASIS c2">yours</span>.
434 In fact, we encourage this level of scrutiny. It is one reason we use
435 <span class="APPLICATION">Privoxy</span> ourselves.</p>
439 <h3 class="SECT2"><a name="LICENSE" id="LICENSE">1.14. Is there is a
440 license or fee? What about a warranty? Registration?</a></h3>
442 <p><span class="APPLICATION">Privoxy</span> is free software and
443 licensed under the <a href=
444 "http://www.gnu.org/licenses/old-licenses/gpl-2.0.html" target=
445 "_top">GNU General Public License (GPL) version 2</a>. It is free to
446 use, copy, modify or distribute as you wish under the terms of this
447 license. Please see the <a href="copyright.html">Copyright</a> section
448 for more information on the license and copyright. Or the <tt class=
449 "FILENAME">LICENSE</tt> file that should be included.</p>
451 <p>There is <span class="emphasis EMPHASIS c2">no warranty</span> of
452 any kind, expressed, implied or otherwise. That is something that would
453 cost real money ;-) There is no registration either.</p>
457 <h3 class="SECT2"><a name="SPYWARE" id="SPYWARE">1.15. Can Privoxy
458 remove spyware? Adware? Viruses?</a></h3>
460 <p>No, at least not reliably enough to trust it. <span class=
461 "APPLICATION">Privoxy</span> is not designed to be a malware removal
462 tool and the default configuration doesn't even try to filter out any
465 <p><span class="APPLICATION">Privoxy</span> could help prevent contact
466 from (known) sites that use such tactics with appropriate configuration
467 rules, and thus could conceivably prevent contamination from such
468 sites. However, keeping such a configuration up to date would require a
469 lot of time and effort that would be better spend on keeping your
470 software itself up to date so it doesn't have known
475 <h3 class="SECT2"><a name="OTHERADS" id="OTHERADS">1.16. Can I use
476 Privoxy with other ad-blocking software?</a></h3>
478 <p><span class="APPLICATION">Privoxy</span> should work fine with other
479 proxies and other software in general.</p>
481 <p>But it is probably not necessary to use <span class=
482 "APPLICATION">Privoxy</span> in conjunction with other ad-blocking
483 products, and this could conceivably cause undesirable results. It
484 might be better to choose one software or the other and work a little
485 to tweak its configuration to your liking.</p>
487 <p>Note that this is an advice specific to ad blocking.</p>
491 <h3 class="SECT2"><a name="HELP-THE-DEVELOPERS" id=
492 "HELP-THE-DEVELOPERS">1.17. I would like to help you, what can I
496 <h4 class="SECT3"><a name="PARTICIPATE" id="PARTICIPATE">1.17.1.
497 Would you like to participate?</a></h4>
499 <p>Well, we <span class="emphasis EMPHASIS c2">always</span> need
500 help. There is something for everybody who wants to help us. We
501 welcome new developers, packagers, testers, documentation writers or
502 really anyone with a desire to help in any way. You <span class=
503 "emphasis EMPHASIS c2">DO NOT</span> need to be a <span class=
504 "QUOTE">"programmer"</span>. There are many other tasks available. In
505 fact, the programmers often can't spend as much time programming
506 because of some of the other, more mundane things that need to be
507 done, like checking the Tracker feedback sections or responding to
508 user questions on the mailing lists.</p>
510 <p>So first thing, subscribe to the <a href=
511 "https://lists.sourceforge.net/lists/listinfo/ijbswa-users" target=
512 "_top">Privoxy Users</a> or the <a href=
513 "https://lists.sourceforge.net/lists/listinfo/ijbswa-developers"
514 target="_top">Privoxy Developers</a> mailing list, join the
515 discussion, help out other users, provide general feedback or report
516 problems you noticed.</p>
518 <p>If you intend to help out with the trackers, you also might want
519 to <a href="https://sourceforge.net/account/register.php" target=
520 "_top">get an account on SourceForge.net</a> so we don't confuse you
521 with the other name-less users.</p>
523 <p>We also have a <a href="../developer-manual/index.html" target=
524 "_top">Developer's Manual</a>. While it is partly out of date, it's
525 still worth reading.</p>
528 "http://ijbswa.cvs.sourceforge.net/viewvc/ijbswa/current/TODO?view=markup"
529 target="_top">TODO list</a> may be of interest to you as well. Please
530 let us know if you want to work on one of the items listed.</p>
534 <h4 class="SECT3"><a name="DONATE" id="DONATE">1.17.2. Would you like
537 <p><span class="APPLICATION">Privoxy</span> is developed by unpaid
538 volunteers and thus our current running costs are pretty low.
539 Nevertheless, we have plans that will cost money in the future. They
540 include, but aren't limited to spending money on:</p>
544 <p>Hardware to help make sure <span class=
545 "APPLICATION">Privoxy</span> keeps running on platforms the
546 developers currently can't test on and can be ported to
551 <p>Technical books to educate our developers about said platforms
552 or to improve their knowledge in general.</p>
556 <p>More reliable hosting,</p>
560 <p>We would like to get this money through donations made by our
563 <p><span class="APPLICATION">Privoxy</span> has therefore become an
564 associated project of <a href=
565 "http://www.spi-inc.org/about-spi/about-spi" target="_top">Software
566 in the Public Interest (SPI)</a>, which allows us to receive
567 donations. In the United States they are tax-deductible, in a few
568 other western countries they might be tax-deductible in the
571 <p>If you read this section before you may notice that paying for the
572 project domain privoxy.org is no longer on the list. It has been
573 transferred to SPI is sponsored by Mythic Beasts Ltd.</p>
575 <p>If you enjoy our software and feel like helping out with a
576 donation, please have a look at <a href=
577 "http://www.spi-inc.org/donations" target="_top">SPI's donation
578 page</a> to see what the options are. If you have any questions
579 regarding donations please mail to either the public user mailing
580 list or, if it's a private matter, to <a href=
581 "mailto:fk@fabiankeil.de" target="_top">Fabian Keil</a> (Privoxy's
582 SPI liason) directly.</p>
587 <div class="NAVFOOTER">
588 <hr class="c1" width="100%">
590 <table summary="Footer navigation table" width="100%" border="0"
591 cellpadding="0" cellspacing="0">
593 <td width="33%" align="left" valign="top"><a href="index.html"
594 accesskey="P">Prev</a></td>
596 <td width="34%" align="center" valign="top"><a href="index.html"
597 accesskey="H">Home</a></td>
599 <td width="33%" align="right" valign="top"><a href=
600 "installation.html" accesskey="N">Next</a></td>
604 <td width="33%" align="left" valign="top">Privoxy Frequently Asked
607 <td width="34%" align="center" valign="top"> </td>
609 <td width="33%" align="right" valign="top">Installation</td>