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40 >Privoxy Frequently Asked Questions</TH
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77 >1. General Information</A
85 >1.1. Who should use Privoxy?</A
88 > Anyone that is interested in security, privacy, or in
89 finer-grained control over their web and Internet experience.
90 Everyone is encouraged to try <SPAN
102 >1.2. Is Privoxy the best choice for
109 > is certainly a good choice, especially for those who want more
110 control and security. Those that have the ability to fine-tune their installation
111 will benefit the most. One of <SPAN
115 strength's is that it is highly configurable giving you the ability to
116 completely personalize your installation. Being familiar with, or at least
117 having an interest in learning about <A
118 HREF="http://en.wikipedia.org/wiki/Http"
121 > and other networking
123 HREF="http://en.wikipedia.org/wiki/Html"
128 HREF="http://en.wikipedia.org/wiki/Internet_Protocol"
134 HREF="http://en.wikipedia.org/wiki/Regular_expressions"
142 will be a big plus and will help you get the most out of <SPAN
146 A new installation just includes a very basic configuration. The user
147 should take this as a starting point only, and enhance it as he or she
148 sees fit. In fact, the user is encouraged, and expected to, fine-tune the
155 > configuration can be done
157 HREF="http://en.wikipedia.org/wiki/Web_browser"
161 But there are areas where configuration is done using a
163 HREF="http://en.wikipedia.org/wiki/Text_editors"
167 to edit configuration files.
176 >1.3. What is a <SPAN
184 HREF="http://en.wikipedia.org/wiki/Proxy_server"
188 is a service, based on a software such as
192 >, that clients (i.e. browsers) can use
193 instead of connecting directly to web servers on the Internet. The
194 clients then ask the proxy to fetch the objects they need (web pages,
195 images, movies etc) on their behalf, and when the proxy has done so, it
196 hands the results back to the client. It is a <SPAN
201 HREF="http://en.wikipedia.org/wiki/Proxy_server"
208 > There are many reasons to use web proxies, such as security (firewalling),
209 efficiency (caching) and others, and there are any number of proxies
210 to accommodate those needs.
216 > is a proxy that is primarily focused on privacy
217 protection, ad and junk elimination and freeing the user from restrictions placed on his
218 activities. Sitting between your browser(s) and the Internet,
219 it is in a perfect position to filter outbound personal information that your
220 browser is leaking, as well as inbound junk. It uses a variety of techniques to do
221 this, all of which are under your complete control via the various configuration
222 files and options. Being a proxy also makes it easier to share
223 configurations among multiple browsers and/or users.
232 >1.4. Does Privoxy do anything more than ad blocking?</A
236 Yes, ad blocking is but one possible use. There are many, many ways <SPAN
240 can be used to sanitize and customize web browsing. </P
248 >1.5. What is this new version of
255 > A long time ago, there was the
257 HREF="http://www.junkbusters.com/ijb.html"
261 >Internet Junkbuster</SPAN
264 by Anonymous Coders and <A
265 HREF="http://www.junkbusters.com/"
269 >. This saved many users a lot of pain in the early days of
270 web advertising and user tracking.</P
272 > But the web, its protocols and standards, and with it, the techniques for
273 forcing ads on users, give up autonomy over their browsing, and
274 for tracking them, keeps evolving. Unfortunately, the <SPAN
278 > did not. Version 2.0.2, published in 1998, was
279 (and is) the last official
281 HREF="http://www.junkbusters.com/ijbdist.html#release"
286 HREF="http://www.junkbusters.com"
288 >Junkbusters Corporation</A
290 Fortunately, it had been released under the GNU
292 HREF="http://www.gnu.org/licenses/gpl.html"
295 >, which allowed further
296 development by others.</P
298 > So Stefan Waldherr started maintaining an
300 HREF="http://www.waldherr.org/junkbuster/"
302 >improved version of the
304 >, to which eventually a number of people contributed patches.
305 It could already replace banners with a transparent image, and had a first
306 version of pop-up killing, but it was still very closely based on the
307 original, with all its limitations, such as the lack of HTTP/1.1 support,
308 flexible per-site configuration, or content modification. The last release
309 from this effort was version 2.0.2-10, published in 2000.</P
313 HREF="http://www.privoxy.org/user-manual/copyright.html#AUTHORS"
317 picked up the thread, and started turning the software inside out, upside down,
318 and then reassembled it, adding many
320 HREF="http://www.privoxy.org/user-manual/introduction.html#FEATURES"
326 > The result of this is <SPAN
330 stable version, 3.0, was released August, 2002.
342 >? Why change the name from
343 Junkbuster at all?</A
346 > Though outdated, <A
347 HREF="http://junkbusters.com/"
349 >Junkbusters Corporation</A
351 continues to offer their original version of the <SPAN
359 >-derived software under the same name
362 > There are also potential legal complications from our use of the
366 > name, which is a registered trademark of
368 HREF="http://junkbusters.com/"
370 >Junkbusters Corporation</A
372 There are, however, no objections from Junkbusters Corporation to the
376 > project itself, and they, in fact, still
377 share our ideals and goals.</P
379 > The developers also believed that there are so many improvements over the original
380 code, that it was time to make a clean break from the past and make
381 a name in their own right.</P
393 >Privacy Enhancing Proxy</I
397 modification and junk suppression gives <SPAN
404 control, more freedom, and allows you to browse your personal and
422 >1.7. How does Privoxy differ
423 from the old Junkbuster?</A
433 > left off. All the old features remain.
437 > still blocks ads and banners,
439 HREF="http://en.wikipedia.org/wiki/Browser_cookie"
443 helps protect your privacy. But, these have all been greatly enhanced, and many,
444 many new features have been added, all in the same vein.
450 >'s new features include:</P
457 > Integrated browser based configuration and control utility at <A
458 HREF="http://config.privoxy.org/"
460 >http://config.privoxy.org/</A
467 tracing of rule and filter effects. Remote toggling.
472 > Web page filtering (text replacements, removes banners based on size,
476 >, JavaScript and HTML annoyances,
477 pop-up windows, header manipulation, etc.)
482 > Modularized configuration that allows for standard settings and
483 user settings to reside in separate files, so that installing updated
484 actions files won't overwrite individual user settings.
489 > Support for Perl Compatible Regular Expressions in the configuration files, and
490 generally a more sophisticated and flexible configuration syntax over
496 > Improved cookie management features (e.g. session based cookies).
506 > Bypass many click-tracking scripts (avoids script redirection).
511 > Multi-threaded (POSIX and native threads).
516 > User-customizable HTML templates for all proxy-generated pages (e.g. "blocked" page).
521 > Auto-detection and re-reading of config file changes.
526 > Improved signal handling, and a true daemon mode (Unix).
531 > Every feature now controllable on a per-site or per-location basis, configuration
532 more powerful and versatile over-all.
537 > Many smaller new features added, limitations and bugs removed, and security holes fixed.
549 >1.8. How does Privoxy know what is
550 an ad, and what is not?</A
556 >'s approach to blocking ads is twofold:</P
558 > First, there are certain patterns in the <SPAN
565 of banner images. This applies to both the path (you wouldn't guess how many
566 web sites serve their banners from a directory called <SPAN
570 and the host (blocking the big banner hosting services like doublecklick.net
571 already helps a lot). <SPAN
574 > takes advantage of this
576 HREF="../user-manual/actions-file.html#AF-PATTERNS"
580 > to sort out and block the requests for things that sound
581 like they would be ads or banners.</P
583 > Second, banners tend to come in certain <SPAN
590 can't tell the size of an image by its URL without downloading it, and if you
591 do, it's too late to save bandwidth. Therefore, <SPAN
595 also inspects the HTML sources of web pages while they are loaded, and replaces
596 references to images with standard banner sizes by dummy references, so that
597 your browser doesn't request them anymore in the first place.</P
599 > Both of this involves a certain amount of guesswork and is, of course, freely
600 and readily configurable.</P
608 >1.9. Can Privoxy make mistakes?
609 This does not sound very scientific.</A
612 > Actually, it's a black art ;-) And yes, it is always possible to have a broad
613 rule accidentally block or change something by mistake. You will almost surely
614 run into such situations at some point. It is tricky writing rules to
615 cover every conceivable possibility, and not occasionally get false positives.</P
617 > But this should not be a big concern since the
621 > configuration is very flexible, and
622 includes tools to help identify these types of situations so they can be
623 addressed as needed, allowing you to customize your installation.
625 HREF="trouble.html#BADSITE"
626 >See the Troubleshooting section below</A
635 >1.10. Will I have to configure Privoxy
636 before I can use it?</A
639 > No, not really. The default installation should give you a good starting
640 point, and block <SPAN
646 > ads and unwanted content. Many of
647 the more advanced features are off by default, and would require you to
650 > You do have to set up your browser to use
655 HREF="installation.html#FIRSTSTEP"
656 >Installation section below</A
659 > And you will certainly run into situations where there are false positives,
660 or ads not being blocked that you may not want to see. In these cases, you
661 would certainly benefit by customizing <SPAN
665 configuration to more closely match your individual situation. And we would
666 encourage you to do this. This is where the real power of
678 >1.11. Can Privoxy run as a server on a network?</A
685 > runs as a server already, and can easily be configured to
689 > more than one client. See <A
690 HREF="configuration.html#LANCONFIG"
691 > How can I set up Privoxy to act as a proxy for my LAN</A
700 >1.12. My browser does the same things as
701 Privoxy. Why should I use Privoxy at all?</A
704 > Modern browsers do indeed have <SPAN
711 functionality as <SPAN
715 adequate for you. But <SPAN
719 versatile and powerful, and can do a number of things that browsers just can't.
722 > In addition, a proxy is good choice if you use multiple browsers, or
723 have a LAN with multiple computers since <SPAN
726 > can run as a server
727 application. This way all the configuration is in one place, and you don't
728 have to maintain a similar configuration for possibly many browsers or
738 >1.13. Why should I trust Privoxy?</A
741 > The most important reason is because you have access to
748 >, and you can control everything. You can
749 check every line of every configuration file yourself. You can check every
750 last bit of source code should you desire. And even if you can't read code,
751 there should be some comfort in knowing that other people can,
752 and do read it. You can build the software from scratch, if you want,
753 so that you know the executable is clean, and that it is
760 >. In fact, we encourage this level of scrutiny. It
761 is one reason we use <SPAN
773 >1.14. Is there is a license or fee? What about a
774 warranty? Registration?</A
780 > is licensed under the <A
781 HREF="http://www.gnu.org/licenses/old-licenses/gpl-2.0.html"
783 >GNU General Public License (GPL) version 2</A
785 It is free to use, copy, modify or distribute as you wish under the terms of this
786 license. Please see the <A
787 HREF="copyright.html"
790 information on the license and copyright. Or the <TT
794 that should be included.
803 > of any kind, expressed, implied or otherwise.
804 That is something that would cost real money ;-) There is no registration either.
824 >1.15. Can Privoxy remove spyware? Adware? Viruses?</A
827 > No, at least not reliably enough to trust it. <SPAN
830 > is not designed to be
831 a malware removal tool and the default configuration doesn't even try to
832 filter out any malware.</P
837 > could help prevent contact from (known) sites that use such
838 tactics with appropriate configuration rules, and thus could conceivably
839 prevent contamination from such sites.</P
847 >1.16. Can I use Privoxy with other ad-blocking software?</A
853 > should work fine with other proxies and other software in general.</P
855 > But it is probably not necessary to use <SPAN
858 > in conjunction with other
859 ad-blocking products, and this could conceivably cause undesirable results.
860 It would be better to choose one software or the other and work a little to
861 tweak its configuration to your liking.</P
869 >1.17. I would like to help you, what can I do?</A
877 >1.17.1. Would you like to participate?</A
886 > need help. There is something for
887 everybody who wants to help us. We welcome new developers, packagers,
888 testers, documentation writers or really anyone with a desire to help in
899 >. There are many other tasks available. In fact,
900 the programmers often can't spend as much time programming because of some
901 of the other, more mundane things that need to be done, like checking the
902 Tracker feedback sections.
906 HREF="https://sourceforge.net/account/register.php"
908 >get an account on SourceForge.net</A
910 and mail your id to the <A
911 HREF="mailto:ijbswa-developers@lists.sourceforge.net"
915 >. Then, please read the <A
916 HREF="../developer-manual/index.html"
918 >Developer's Manual</A
920 the pertinent sections.</P
927 NAME="JOINTEAM-MONEY"
928 >1.17.2. Contribute!</A
931 > We, of course, welcome donations and could use money for domain registering,
932 buying software to test <SPAN
935 > with, and, of course,
936 for regular world-wide get-togethers (hahaha). If you enjoy the software and feel
937 like helping us with a donation, just <A
938 HREF="mailto: ijbswa-developers@lists.sourceforge.net"
948 NAME="JOINTEAM-SOFTWARE"
952 > If you are a vendor of a web-related software like a browser, web server
953 or proxy, and would like us to ensure that <SPAN
957 runs smoothly with your product, you might consider supplying us with a
958 copy or license. We can't, however, guarantee that we will fix all potential
959 compatibility issues as a result.</P
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