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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
238 Yes, ad blocking is but one possible use. There are many, many ways <SPAN
242 can be used to sanitize and customize web browsing. </P
250 >1.5. What is this new version of
257 > A long time ago, there was the
259 HREF="http://www.junkbusters.com/ijb.html"
263 >Internet Junkbuster</SPAN
266 by Anonymous Coders and <A
267 HREF="http://www.junkbusters.com/"
271 >. This saved many users a lot of pain in the early days of
272 web advertising and user tracking.</P
274 > But the web, its protocols and standards, and with it, the techniques for
275 forcing ads on users, give up autonomy over their browsing, and
276 for tracking them, keeps evolving. Unfortunately, the <SPAN
280 > did not. Version 2.0.2, published in 1998, was
281 (and is) the last official
283 HREF="http://www.junkbusters.com/ijbdist.html#release"
288 HREF="http://www.junkbusters.com"
290 >Junkbusters Corporation</A
292 Fortunately, it had been released under the GNU
294 HREF="http://www.gnu.org/licenses/old-licenses/gpl-2.0.html"
298 which allowed further development by others.</P
300 > So Stefan Waldherr started maintaining an improved version of the
301 software, to which eventually a number of people contributed patches.
302 It could already replace banners with a transparent image, and had a first
303 version of pop-up killing, but it was still very closely based on the
304 original, with all its limitations, such as the lack of HTTP/1.1 support,
305 flexible per-site configuration, or content modification. The last release
306 from this effort was version 2.0.2-10, published in 2000.</P
310 HREF="http://www.privoxy.org/user-manual/copyright.html#AUTHORS"
314 picked up the thread, and started turning the software inside out, upside down,
315 and then reassembled it, adding many
317 HREF="http://www.privoxy.org/user-manual/introduction.html#FEATURES"
323 > The result of this is <SPAN
327 stable version, 3.0, was released August, 2002.
339 >? Why change the name from
340 Junkbuster at all?</A
343 > Though outdated, <A
344 HREF="http://junkbusters.com/"
346 >Junkbusters Corporation</A
348 continues to offer their original version of the <SPAN
356 >-derived software under the same name
359 > There are also potential legal complications from our use of the
363 > name, which is a registered trademark of
365 HREF="http://junkbusters.com/"
367 >Junkbusters Corporation</A
369 There are, however, no objections from Junkbusters Corporation to the
373 > project itself, and they, in fact, still
374 share our ideals and goals.</P
376 > The developers also believed that there are so many improvements over the original
377 code, that it was time to make a clean break from the past and make
378 a name in their own right.</P
390 >Privacy Enhancing Proxy</I
394 modification and junk suppression gives <SPAN
401 control, more freedom, and allows you to browse your personal and
419 >1.7. How does Privoxy differ
420 from the old Junkbuster?</A
434 > still blocks ads and banners,
436 HREF="http://en.wikipedia.org/wiki/Browser_cookie"
440 helps protect your privacy. But, most of these features have been enhanced,
441 and many new ones have been added, all in the same vein.
447 >'s new features include:</P
454 > Supports "Connection: keep-alive". Outgoing connections can
455 be kept alive independently from the client. Currently not
456 available on all platforms.
461 > Supports IPv6, provided the operating system does so too,
462 and the configure script detects it.
467 > Supports tagging which allows to change the behaviour
468 based on client and server headers.
473 > Can be run as an "intercepting" proxy, which obviates the need to
474 configure browsers individually.
479 > Sophisticated actions and filters for manipulating both server and client
485 > Can be chained with other proxies.
490 > Integrated browser-based configuration and control utility at <A
491 HREF="http://config.privoxy.org/"
493 >http://config.privoxy.org/</A
500 tracing of rule and filter effects. Remote toggling.
505 > Web page filtering (text replacements, removes banners based on size,
509 > and HTML annoyances, etc.)
514 > Modularized configuration that allows for standard settings and
515 user settings to reside in separate files, so that installing updated
516 actions files won't overwrite individual user settings.
521 > Support for Perl Compatible Regular Expressions in the configuration files, and
522 a more sophisticated and flexible configuration syntax.
532 > Bypass many click-tracking scripts (avoids script redirection).
537 > User-customizable HTML templates for most proxy-generated pages (e.g. "blocked" page).
542 > Auto-detection and re-reading of config file changes.
547 > Most features are controllable on a per-site or per-location basis.
552 > Many smaller new features added, limitations and bugs removed.
564 >1.8. How does Privoxy know what is
565 an ad, and what is not?</A
571 >'s approach to blocking ads is twofold:</P
573 > First, there are certain patterns in the <SPAN
580 of banner images. This applies to both the path (you wouldn't guess how many
581 web sites serve their banners from a directory called <SPAN
585 and the host (blocking the big banner hosting services like doublecklick.net
586 already helps a lot). <SPAN
589 > takes advantage of this
591 HREF="../user-manual/actions-file.html#AF-PATTERNS"
595 > to sort out and block the requests for things that sound
596 like they would be ads or banners.</P
598 > Second, banners tend to come in certain <SPAN
605 can't tell the size of an image by its URL without downloading it, and if you
606 do, it's too late to save bandwidth. Therefore, <SPAN
610 also inspects the HTML sources of web pages while they are loaded, and replaces
611 references to images with standard banner sizes by dummy references, so that
612 your browser doesn't request them anymore in the first place.</P
614 > Both of this involves a certain amount of guesswork and is, of course, freely
615 and readily configurable.</P
623 >1.9. Can Privoxy make mistakes?
624 This does not sound very scientific.</A
627 > Actually, it's a black art ;-) And yes, it is always possible to have a broad
628 rule accidentally block or change something by mistake. You will almost surely
629 run into such situations at some point. It is tricky writing rules to
630 cover every conceivable possibility, and not occasionally get false positives.</P
632 > But this should not be a big concern since the
636 > configuration is very flexible, and
637 includes tools to help identify these types of situations so they can be
638 addressed as needed, allowing you to customize your installation.
640 HREF="trouble.html#BADSITE"
641 >See the Troubleshooting section below</A
650 >1.10. Will I have to configure Privoxy
651 before I can use it?</A
654 > That depends on your expectations.
655 The default installation should give you a good starting
656 point, and block <SPAN
662 > ads and unwanted content,
663 but many of the more advanced features are off by default, and require
664 you to activate them. </P
666 > You do have to set up your browser to use
671 HREF="installation.html#FIRSTSTEP"
672 >Installation section below</A
675 > And you will certainly run into situations where there are false positives,
676 or ads not being blocked that you may not want to see. In these cases, you
677 would certainly benefit by customizing <SPAN
681 configuration to more closely match your individual situation. And we
682 encourage you to do this. This is where the real power of
694 >1.11. Can Privoxy run as a server on a network?</A
701 > runs as a server already, and can easily be configured to
705 > more than one client. See <A
706 HREF="configuration.html#LANCONFIG"
707 > How can I set up Privoxy to act as a proxy for my LAN</A
716 >1.12. My browser does the same things as
717 Privoxy. Why should I use Privoxy at all?</A
720 > Modern browsers do indeed have <SPAN
727 functionality as <SPAN
731 adequate for you. But <SPAN
735 versatile and powerful, and can probably do a number of things
736 your browser just can't.
739 > In addition, a proxy is good choice if you use multiple browsers, or
740 have a LAN with multiple computers since <SPAN
743 > can run as a server
744 application. This way all the configuration is in one place, and you don't
745 have to maintain a similar configuration for possibly many browsers or
749 > Note, however, that it's recommended to leverage both your browser's
753 > privacy enhancing features
754 at the same time. While your browser probably lacks some features
758 > offers, it should also be able to do some things more
759 reliable, for example restricting and suppressing JavaScript.
768 >1.13. Why should I trust Privoxy?</A
771 > The most important reason is because you have access to
778 >, and you can control everything. You can
779 check every line of every configuration file yourself. You can check every
780 last bit of source code should you desire. And even if you can't read code,
781 there should be some comfort in knowing that other people can,
782 and do read it. You can build the software from scratch, if you want,
783 so that you know the executable is clean, and that it is
790 >. In fact, we encourage this level of scrutiny. It
791 is one reason we use <SPAN
803 >1.14. Is there is a license or fee? What about a
804 warranty? Registration?</A
810 > is free software and licensed under the <A
811 HREF="http://www.gnu.org/licenses/old-licenses/gpl-2.0.html"
813 >GNU General Public License (GPL) version 2</A
815 It is free to use, copy, modify or distribute as you wish under the terms of this
816 license. Please see the <A
817 HREF="copyright.html"
820 information on the license and copyright. Or the <TT
824 that should be included.
833 > of any kind, expressed, implied or otherwise.
834 That is something that would cost real money ;-) There is no registration either.
843 >1.15. Can Privoxy remove spyware? Adware? Viruses?</A
846 > No, at least not reliably enough to trust it. <SPAN
849 > is not designed to be
850 a malware removal tool and the default configuration doesn't even try to
851 filter out any malware.</P
856 > could help prevent contact from (known) sites that use such
857 tactics with appropriate configuration rules, and thus could conceivably
858 prevent contamination from such sites. However, keeping such a configuration
859 up to date would require a lot of time and effort that would be better spend
860 on keeping your software itself up to date so it doesn't have known
869 >1.16. Can I use Privoxy with other ad-blocking software?</A
875 > should work fine with other proxies and other software in general.</P
877 > But it is probably not necessary to use <SPAN
880 > in conjunction with other
881 ad-blocking products, and this could conceivably cause undesirable results.
882 It might be better to choose one software or the other and work a little to
883 tweak its configuration to your liking.</P
885 > Note that this is an advice specific to ad blocking.</P
892 NAME="HELP-THE-DEVELOPERS"
893 >1.17. I would like to help you, what can I do?</A
901 >1.17.1. Would you like to participate?</A
910 > need help. There is something for
911 everybody who wants to help us. We welcome new developers, packagers,
912 testers, documentation writers or really anyone with a desire to help in
923 >. There are many other tasks available. In fact,
924 the programmers often can't spend as much time programming because of some
925 of the other, more mundane things that need to be done, like checking the
926 Tracker feedback sections or responding to user questions on the mailing
930 > So first thing, subscribe to the <A
931 HREF="https://lists.sourceforge.net/lists/listinfo/ijbswa-users"
936 HREF="https://lists.sourceforge.net/lists/listinfo/ijbswa-developers"
940 > mailing list, join the discussion, help out other users, provide general
941 feedback or report problems you noticed.
944 > If you intend to help out with the trackers, you also might want to <A
945 HREF="https://sourceforge.net/account/register.php"
947 >get an account on SourceForge.net</A
949 so we don't confuse you with the other name-less users.
953 HREF="../developer-manual/index.html"
955 >Developer's Manual</A
957 While it is partly out of date, it's still worth reading.</P
960 HREF="http://ijbswa.cvs.sourceforge.net/viewvc/ijbswa/current/TODO?view=markup"
964 may be of interest to you as well.
965 Please let us know if you want to work on one of the items listed.</P
973 >1.17.2. Would you like to donate?</A
979 > is developed by unpaid volunteers
980 and thus our current running costs are pretty low. Nevertheless, we
981 have plans that will cost money in the future. We would like to get
982 this money through donations made by our users.</P
987 > has therefore become an associated
989 HREF="http://www.spi-inc.org/about-spi/about-spi"
992 in the Public Interest (SPI)</A
993 >, which allows us to receive tax-deductible
994 donations in most western countries.</P
996 > We intend to use the donations to pay for our domain after transfering
997 it to SPI. Our goal is to make sure there's no single point of failure
998 and the bill gets paid and the site keeps running even if a some of
999 the currently active developers were to suddenly disappear for a while.</P
1001 > We would also like to spend some money on more reliable hosting,
1002 on hardware to help make sure <SPAN
1006 keeps running on platforms the developers currently can't test on,
1007 and on technical books to educate our developers about said platforms
1008 or to improve their knowledge in general.</P
1010 > If you enjoy our software and feel like helping out with a donation,
1011 please have a look at
1013 HREF="http://www.spi-inc.org/donations"
1015 >SPI's donation page</A
1017 to see what the options are.</P
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