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43 >Privoxy Frequently Asked Questions</TH
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80 >1. General Information</A
88 >1.1. Who should give <SPAN
94 > Anyone who is interested in security, privacy, or in
95 finer-grained control over their web and Internet experience.
104 >1.2. Is Privoxy the best choice for
111 > is certainly a good choice, especially for those who want more
112 control and security. Those with the willingness to read the documentation
113 and the ability to fine-tune their installation will benefit the most.
120 strengths is that it is highly configurable giving you the ability to
121 completely personalize your installation. Being familiar with, or at least
122 having an interest in learning about <A
123 HREF="http://en.wikipedia.org/wiki/Http"
126 > and other networking
128 HREF="http://en.wikipedia.org/wiki/Html"
133 HREF="http://en.wikipedia.org/wiki/Regular_expressions"
141 will be a big plus and will help you get the most out of <SPAN
145 A new installation just includes a very basic configuration. The user
146 should take this as a starting point only, and enhance it as he or she
147 sees fit. In fact, the user is encouraged, and expected to, fine-tune the
154 > configuration can be done
156 HREF="http://en.wikipedia.org/wiki/Web_browser"
160 But there are areas where configuration is done using a
162 HREF="http://en.wikipedia.org/wiki/Text_editors"
166 to edit configuration files. Also note that the web-based action editor
167 doesn't use authentication and should only be enabled in environments
168 where all clients with access to <SPAN
171 > listening port can be trusted.
180 >1.3. What is a <SPAN
188 HREF="http://en.wikipedia.org/wiki/Proxy_server"
192 is a service, based on a software such as <SPAN
196 (i.e. browsers) can use instead of connecting to web servers directly.
197 The clients then ask the proxy to request objects (web pages, images, movies etc)
198 on their behalf and to forward the data to the clients.
204 HREF="http://en.wikipedia.org/wiki/Proxy_server"
206 >Wikipedia's proxy definition</A
210 > There are many reasons to use web proxies, such as security (firewalling),
211 efficiency (caching) and others, and there are any number of proxies
212 to accommodate those needs.
218 > is a proxy that is primarily focused on
219 privacy enhancement, ad and junk elimination and freeing the user from
220 restrictions placed on his activities. Sitting between your browser(s) and the Internet,
221 it is in a perfect position to filter outbound personal information that your
222 browser is leaking, as well as inbound junk. It uses a variety of techniques to do
223 this, all of which are under your complete control via the various configuration
224 files and options. Being a proxy also makes it easier to share
225 configurations among multiple browsers and/or users.
234 >1.4. Does Privoxy do anything more than ad blocking?</A
237 > Yes, ad blocking is but one possible use. There are many, many ways <SPAN
241 can be used to sanitize and customize web browsing.</P
249 >1.5. What is this new version of
256 > A long time ago, there was the <SPAN
258 >Internet Junkbuster</SPAN
260 by Anonymous Coders and Junkbusters Corporation. This saved many users a lot of
261 pain in the early days of web advertising and user tracking.</P
263 > But the web, its protocols and standards, and with it, the techniques for
264 forcing ads on users, give up autonomy over their browsing, and
265 for tracking them, keeps evolving. Unfortunately, the <SPAN
269 > did not. Version 2.0.2, published in 1998, was
270 the last official release, available from Junkbusters Corporation.
271 Fortunately, it had been released under the GNU
273 HREF="http://www.gnu.org/licenses/old-licenses/gpl-2.0.html"
277 which allowed further development by others.</P
279 > So Stefan Waldherr started maintaining an improved version of the
280 software, to which eventually a number of people contributed patches.
281 It could already replace banners with a transparent image, and had a first
282 version of pop-up killing, but it was still very closely based on the
283 original, with all its limitations, such as the lack of HTTP/1.1 support,
284 flexible per-site configuration, or content modification. The last release
285 from this effort was version 2.0.2-10, published in 2000.</P
289 HREF="https://www.privoxy.org/user-manual/copyright.html#AUTHORS"
293 picked up the thread, and started turning the software inside out, upside down,
294 and then reassembled it, adding many
296 HREF="https://www.privoxy.org/user-manual/introduction.html#FEATURES"
302 > The result of this is <SPAN
306 stable version, 3.0, was released August, 2002.
309 > As of 2012 the Junkbusters Corporation's website (http://www.junkbusters.com/)
310 has been shut down, but Privoxy is still actively maintained.</P
321 >? Why change the name from
322 Junkbuster at all?</A
325 > Though outdated, Junkbusters Corporation continued to offer their original
328 >Internet Junkbuster</SPAN
330 so publishing our <SPAN
334 under the same name would have led to confusion.</P
336 > There were also potential legal reasons not to use the
340 > name, as it was (and maybe still is)
341 a registered trademark of Junkbusters Corporation.
342 There were, however, no objections from Junkbusters Corporation to the
346 > project itself, and they, in fact,
347 shared our ideals and goals.</P
349 > The Privoxy developers also believed that there were so many improvements
350 over the original code, that it was time to make a clean break from the past
351 and make a name in their own right.</P
363 >Privacy Enhancing Proxy</I
367 modification and junk suppression gives <SPAN
374 control, more freedom, and allows you to browse your personal and
392 >1.7. How does Privoxy differ
393 from the old Junkbuster?</A
407 > still blocks ads and banners,
409 HREF="http://en.wikipedia.org/wiki/Browser_cookie"
413 helps protect your privacy. But, most of these features have been enhanced,
414 and many new ones have been added, all in the same vein.
420 >'s new features include:</P
426 > Supports "Connection: keep-alive". Outgoing connections can
427 be kept alive independently from the client.
432 > Supports IPv6, provided the operating system does so too,
433 and the configure script detects it.
438 > Supports tagging which allows to change the behaviour
439 based on client and server headers.
444 > Can be run as an "intercepting" proxy, which obviates the need to
445 configure browsers individually.
450 > Sophisticated actions and filters for manipulating both server and client
456 > Can be chained with other proxies.
461 > Integrated browser-based configuration and control utility at <A
462 HREF="http://config.privoxy.org/"
464 >http://config.privoxy.org/</A
471 tracing of rule and filter effects. Remote toggling.
476 > Web page filtering (text replacements, removes banners based on size,
480 > and HTML annoyances, etc.)
485 > Modularized configuration that allows for standard settings and
486 user settings to reside in separate files, so that installing updated
487 actions files won't overwrite individual user settings.
492 > Support for Perl Compatible Regular Expressions in the configuration files, and
493 a more sophisticated and flexible configuration syntax.
503 > Bypass many click-tracking scripts (avoids script redirection).
508 > User-customizable HTML templates for most proxy-generated pages (e.g. "blocked" page).
513 > Auto-detection and re-reading of config file changes.
518 > Most features are controllable on a per-site or per-location basis.
523 > Many smaller new features added, limitations and bugs removed.
534 >1.8. How does Privoxy know what is an ad, and what is not?</A
540 >'s approach to blocking ads is twofold:</P
542 > First, there are certain patterns in the <SPAN
549 of banner images. This applies to both the path (you wouldn't guess how many
550 web sites serve their banners from a directory called <SPAN
554 and the host (blocking the big banner hosting services like doublecklick.net
555 already helps a lot). <SPAN
558 > takes advantage of this
560 HREF="../user-manual/actions-file.html#AF-PATTERNS"
564 > to sort out and block the requests for things that sound
565 like they would be ads or banners.</P
567 > Second, banners tend to come in certain <SPAN
574 can't tell the size of an image by its URL without downloading it, and if you
575 do, it's too late to save bandwidth. Therefore, <SPAN
579 also inspects the HTML sources of web pages while they are loaded, and replaces
580 references to images with standard banner sizes by dummy references, so that
581 your browser doesn't request them anymore in the first place.</P
583 > Both of this involves a certain amount of guesswork and is, of course, freely
584 and readily configurable.</P
592 >1.9. Can Privoxy make mistakes?
593 This does not sound very scientific.</A
596 > Actually, it's a black art ;-) And yes, it is always possible to have a broad
597 rule accidentally block or change something by mistake. You will almost surely
598 run into such situations at some point. It is tricky writing rules to
599 cover every conceivable possibility, and not occasionally get false positives.</P
601 > But this should not be a big concern since the
605 > configuration is very flexible, and
606 includes tools to help identify these types of situations so they can be
607 addressed as needed, allowing you to customize your installation.
609 HREF="trouble.html#BADSITE"
610 >See the Troubleshooting section below</A
619 >1.10. Will I have to configure Privoxy
620 before I can use it?</A
623 > That depends on your expectations.
624 The default installation should give you a good starting
625 point, and block <SPAN
631 > ads and unwanted content,
632 but many of the more advanced features are off by default, and require
633 you to activate them.</P
635 > You do have to set up your browser to use
640 HREF="installation.html#FIRSTSTEP"
641 >Installation section below</A
644 > And you will certainly run into situations where there are false positives,
645 or ads not being blocked that you may not want to see. In these cases, you
646 would certainly benefit by customizing <SPAN
650 configuration to more closely match your individual situation. And we
651 encourage you to do this. This is where the real power of
663 >1.11. Can Privoxy run as a server on a network?</A
669 > runs as a server already, and can easily be configured to
673 > more than one client. See <A
674 HREF="configuration.html#LANCONFIG"
675 > How can I set up Privoxy to act as a proxy for my LAN</A
684 >1.12. My browser does the same things as
685 Privoxy. Why should I use Privoxy at all?</A
688 > Modern browsers do indeed have <SPAN
695 functionality as <SPAN
699 adequate for you. But <SPAN
703 versatile and powerful, and can probably do a number of things
704 your browser just can't.
707 > In addition, a proxy is good choice if you use multiple browsers, or
708 have a LAN with multiple computers since <SPAN
711 > can run as a server
712 application. This way all the configuration is in one place, and you don't
713 have to maintain a similar configuration for possibly many browsers or
717 > Note, however, that it's recommended to leverage both your browser's
721 > privacy enhancing features
722 at the same time. While your browser probably lacks some features
726 > offers, it should also be able to do some things more
727 reliably, for example restricting and suppressing JavaScript.
736 >1.13. Why should I trust Privoxy?</A
739 > The most important reason is because you have access to
746 >, and you can control everything. You can
747 check every line of every configuration file yourself. You can check every
748 last bit of source code should you desire. And even if you can't read code,
749 there should be some comfort in knowing that other people can,
750 and do read it. You can build the software from scratch, if you want,
751 so that you know the executable is clean, and that it is
758 >. In fact, we encourage this level of scrutiny. It
759 is one reason we use <SPAN
771 >1.14. Is there is a license or fee? What about a
772 warranty? Registration?</A
778 > is free software and licensed under the <A
779 HREF="http://www.gnu.org/licenses/old-licenses/gpl-2.0.html"
781 >GNU General Public License (GPL) version 2</A
783 It is free to use, copy, modify or distribute as you wish under the terms of this
784 license. Please see the <A
785 HREF="copyright.html"
788 information on the license and copyright. Or the <TT
792 that should be included.
801 > of any kind, expressed, implied or otherwise.
802 That is something that would cost real money ;-) There is no registration either.
811 >1.15. Can Privoxy remove spyware? Adware? Viruses?</A
814 > No, at least not reliably enough to trust it. <SPAN
817 > is not designed to be
818 a malware removal tool and the default configuration doesn't even try to
819 filter out any malware.</P
824 > could help prevent contact from (known) sites that use such
825 tactics with appropriate configuration rules, and thus could conceivably
826 prevent contamination from such sites. However, keeping such a configuration
827 up to date would require a lot of time and effort that would be better spend
828 on keeping your software itself up to date so it doesn't have known
837 >1.16. Can I use Privoxy with other ad-blocking software?</A
843 > should work fine with other proxies and other software in general.</P
845 > But it is probably not necessary to use <SPAN
848 > in conjunction with other
849 ad-blocking products, and this could conceivably cause undesirable results.
850 It might be better to choose one software or the other and work a little to
851 tweak its configuration to your liking.</P
853 > Note that this is an advice specific to ad blocking.</P
860 NAME="HELP-THE-DEVELOPERS"
861 >1.17. I would like to help you, what can I do?</A
869 >1.17.1. Would you like to participate?</A
878 > need help. There is something for
879 everybody who wants to help us. We welcome new developers, packagers,
880 testers, documentation writers or really anyone with a desire to help in
891 >. There are many other tasks available. In fact,
892 the programmers often can't spend as much time programming because of some
893 of the other, more mundane things that need to be done, like checking the
894 Tracker feedback sections or responding to user questions on the mailing
898 > So first thing, subscribe to the <A
899 HREF="https://lists.privoxy.org/mailman/listinfo/privoxy-users"
904 HREF="https://lists.privoxy.org/mailman/listinfo/privoxy-devel"
908 > mailing list, join the discussion, help out other users, provide general
909 feedback or report problems you noticed.
912 > If you intend to help out with the trackers, you also might want to <A
913 HREF="https://sourceforge.net/user/registration"
915 >get an account on SourceForge.net</A
917 so we don't confuse you with the other name-less users.
921 HREF="../developer-manual/index.html"
923 >Developer's Manual</A
925 While it is partly out of date, it's still worth reading.</P
928 HREF="https://www.privoxy.org/gitweb/?p=privoxy.git;a=blob_plain;f=TODO;hb=HEAD"
932 may be of interest to you as well.
933 Please let us know if you want to work on one of the items listed.</P
941 >1.17.2. Would you like to donate?</A
944 > Donations are welcome. Our
946 HREF="https://www.privoxy.org/gitweb/?p=privoxy.git;a=blob_plain;f=TODO;hb=HEAD"
950 is rather long and being able to pay one (or more) developers to work on Privoxy
951 would make a huge difference, even if it was only for a couple of weeks. Donations may
952 also be used for Privoxy-related travel expenses (for example to attend conferences),
953 for hardware used for Privoxy development and for hosting expenses etc.</P
960 HREF="https://www.spi-inc.org/"
963 in the Public Interest (SPI)</A
964 >, which allows us to receive
965 tax-deductible donations in the United States.
967 HREF="https://www.spi-inc.org/projects/privoxy/"
969 >donate via Paypal</A
972 HREF="https://co.clickandpledge.com/advanced/default.aspx?wid=34115"
974 >Click & Pledge</A
976 For details, please have a look at
978 HREF="https://www.spi-inc.org/donations"
980 >SPI's general donation page</A
983 > You can also donate to Privoxy using a bank account or a "Paypal" address:</P
985 CLASS="LITERALLAYOUT"
986 > Name on account: <A
987 HREF="https://www.zwiebelfreunde.de/"
989 >Zwiebelfreunde e.V.</A
991 IBAN: DE95430609671126825604<br>
992 BIC: GENODEM1GLS<br>
993 Bank: GLS Bank</P
995 CLASS="LITERALLAYOUT"
996 > "Paypal" address: privoxy@zwiebelfreunde.de</P
998 > Donations made through Zwiebelfreunde e.V. are tax-deductible in Germany
999 and other countries that recognize German charitable clubs. Feel free to
1000 use the Subject field to provide a name to be credited and a list of TODO
1001 list items you are interested in the most. For example: Max Mustermann: #16, #1, #14.</P
1003 > Note that donations made through Zwiebelfreunde e.V. currently can't be checked
1004 automatically so you may not get credited right away. The credits currently
1005 reflect donations received before 2016-01-14.</P
1007 > If you have any questions regarding donations please mail to either the
1008 public user mailing list or, if it's a private matter, to
1010 HREF="mailto:fk@fabiankeil.de"
1013 > (Privoxy's SPI liaison)
1023 >1.18. How can I become a sponsor and get my logo or link on privoxy.org?</A
1026 > We are currently offering the following sponsor levels as an experiment:</P
1030 CLASS="VARIABLELIST"
1033 >Gold (10000 EUR/year)</DT
1036 > Logo shown at the bottom of the
1038 HREF="https://www.privoxy.org/"
1040 >Privoxy homepage</A
1042 Logo, link and self description on the
1044 HREF="https://www.privoxy.org/sponsors/"
1051 >Silver (1000 EUR/year)</DT
1054 > Logo shown randomly at the bottom of the
1056 HREF="https://www.privoxy.org/"
1058 >Privoxy homepage</A
1060 Logo, link and self description on the
1062 HREF="https://www.privoxy.org/sponsors/"
1069 >Bronze (500 EUR/year)</DT
1072 > Logo and link on the <A
1073 HREF="https://www.privoxy.org/sponsors/"
1082 > The logo sizes depend on the sponsor level. Logos are served from
1083 our server, no requests are made to the sponsor website unless
1084 the links are being used.</P
1086 > The details may change over time but changes will only affect new sponsors
1087 (or existing sponsors that explicitly agreed to the changes).</P
1089 > If you want to become a sponsor, please contact
1091 HREF="mailto:fk@fabiankeil.de"
1095 New sponsors are only accepted if no developer objects.</P
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