4 >General Information</TITLE
7 CONTENT="Modular DocBook HTML Stylesheet Version 1.76b+
10 TITLE="Privoxy Frequently Asked Questions"
11 HREF="index.html"><LINK
13 TITLE="Privoxy Frequently Asked Questions"
14 HREF="index.html"><LINK
17 HREF="installation.html"><LINK
20 HREF="../p_doc.css"></HEAD
31 SUMMARY="Header navigation table"
40 >Privoxy Frequently Asked Questions</TH
62 HREF="installation.html"
78 >1. General Information</H1
86 >1.1. Who should use Privoxy?</H3
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
103 >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
152 > configuration can be done
154 HREF="http://en.wikipedia.org/wiki/Web_browser"
158 But there are areas where configuration is done using a
160 HREF="http://en.wikipedia.org/wiki/Text_editors"
164 to edit configuration files.
174 >1.3. What is a <SPAN
181 HREF="http://en.wikipedia.org/wiki/Proxy_server"
185 is a service, based on a software such as
189 >, that clients (i.e. browsers) can use
190 instead of connecting directly to web servers on the Internet. The
191 clients then ask the proxy to fetch the objects they need (web pages,
192 images, movies etc) on their behalf, and when the proxy has done so, it
193 hands the results back to the client. It is a <SPAN
198 HREF="http://en.wikipedia.org/wiki/Proxy_server"
205 > There are many reasons to use web proxies, such as security (firewalling),
206 efficiency (caching) and others, and there are any number of proxies
207 to accommodate those needs.
213 > is a proxy that is primarily focused on privacy
214 protection, ad and junk elimination and freeing the user from restrictions placed on his
215 activities. Sitting between your browser(s) and the Internet,
216 it is in a perfect position to filter outbound personal information that your
217 browser is leaking, as well as inbound junk. It uses a variety of techniques to do
218 this, all of which are under your complete control via the various configuration
229 >1.4. What is this new version of
235 > Along time ago, there was the
237 HREF="http://www.junkbusters.com/ijb.html"
241 >Internet Junkbuster</SPAN
244 by Anonymous Coders and <A
245 HREF="http://www.junkbusters.com/"
249 >. This saved many users a lot of pain in the early days of
250 web advertising and user tracking.</P
252 > But the web, its protocols and standards, and with it, the techniques for
253 forcing ads on users, give up autonomy over their browsing, and
254 for tracking them, keeps evolving. Unfortunately, the <SPAN
258 > did not. Version 2.0.2, published in 1998, was
259 (and is) the last official
261 HREF="http://www.junkbusters.com/ijbdist.html#release"
266 HREF="http://www.junkbusters.com"
268 >Junkbusters Corporation</A
270 Fortunately, it had been released under the GNU
272 HREF="http://www.gnu.org/licenses/gpl.html"
275 >, which allowed further
276 development by others.</P
278 > So Stefan Waldherr started maintaining an
280 HREF="http://www.waldherr.org/junkbuster/"
282 >improved version of the
284 >, to which eventually a number of people contributed patches.
285 It could already replace banners with a transparent image, and had a first
286 version of pop-up killing, but it was still very closely based on the
287 original, with all its limitations, such as the lack of HTTP/1.1 support,
288 flexible per-site configuration, or content modification. The last release
289 from this effort was version 2.0.2-10, published in 2000.</P
293 HREF="http://www.privoxy.org/user-manual/copyright.html#AUTHORS"
297 picked up the thread, and started turning the software inside out, upside down,
298 and then reassembled it, adding many
300 HREF="http://www.privoxy.org/user-manual/introduction.html#FEATURES"
306 > The result of this is <SPAN
310 stable version, 3.0, was released August, 2002.
323 >? Why change the name from
324 Junkbuster at all?</H3
327 HREF="http://junkbusters.com/"
329 >Junkbusters Corporation</A
331 continues to offer their original version of the <SPAN
339 >-derived software under the same name
342 > There are also potential legal complications from the continued use of the
346 > name, which is a registered trademark of
348 HREF="http://junkbusters.com/"
350 >Junkbusters Corporation</A
352 There are, however, no objections from Junkbusters Corporation to the
356 > project itself, and they, in fact, still
357 share our ideals and goals.</P
359 > The developers also believed that there are so many improvements over the original
360 code, that it was time to make a clean break from the past and make
361 a name in their own right.</P
373 >Privacy Enhancing Proxy</I
377 modification and junk suppression gives <SPAN
384 control, more freedom, and allows you to browse your personal and
403 >1.6. How does Privoxy differ
404 from the old Junkbuster?</H3
413 > left off. All the old features remain.
417 > still blocks ads and banners,
419 HREF="http://en.wikipedia.org/wiki/Browser_cookie"
423 helps protect your privacy. But, these are all greatly enhanced, and many,
424 many new features have been added, all in the same vein.
427 > The configuration has changed significantly as well. This is something that
428 users will notice right off the bat if upgrading from
442 > and much more has been
443 combined into the <SPAN
446 > files, with a completely different
448 HREF="../user-manual/whatsnew.html"
452 page for the latest updates.</P
457 >'s new features include:</P
464 > Integrated browser based configuration and control utility at <A
465 HREF="http://config.privoxy.org/"
467 >http://config.privoxy.org/</A
474 tracing of rule and filter effects. Remote toggling.
479 > Web page content filtering (removes banners based on size,
483 >, JavaScript and HTML annoyances, pop-up windows, etc.)
488 > Modularized configuration that allows for standard settings and
489 user settings to reside in separate files, so that installing updated
490 actions files won't overwrite individual user settings.
495 > HTTP/1.1 compliant (but not all optional 1.1 features are supported).
500 > Support for Perl Compatible Regular Expressions in the configuration files, and
501 generally a more sophisticated and flexible configuration syntax over
507 > Improved cookie management features (e.g. session based cookies).
517 > Bypass many click-tracking scripts (avoids script redirection).
522 > Multi-threaded (POSIX and native threads).
527 > User-customizable HTML templates for all proxy-generated pages (e.g. "blocked" page).
532 > Auto-detection and re-reading of config file changes.
537 > Improved signal handling, and a true daemon mode (Unix).
542 > Every feature now controllable on a per-site or per-location basis, configuration
543 more powerful and versatile over-all.
548 > Many smaller new features added, limitations and bugs removed, and security holes fixed.
561 >1.7. How does Privoxy know what is
562 an ad, and what is not?</H3
567 >'s approach to blocking ads is twofold:</P
569 > First, there are certain patterns in the <SPAN
576 of banner images. This applies to both the path (you wouldn't guess how many
577 web sites serve their banners from a directory called <SPAN
581 and the host (blocking the big banner hosting services like doublecklick.net
582 already helps a lot). <SPAN
585 > takes advantage of this
587 HREF="../user-manual/actions-file.html#AF-PATTERNS"
591 > to sort out and block the requests for things that sound
592 like they would be ads or banners.</P
594 > Second, banners tend to come in certain <SPAN
601 can't tell the size of an image by its URL without downloading it, and if you
602 do, it's too late to save bandwidth. Therefore, <SPAN
606 also inspects the HTML sources of web pages while they are loaded, and replaces
607 references to images with standard banner sizes by dummy references, so that
608 your browser doesn't request them anymore in the first place.</P
610 > Both of this involves a certain amount of guesswork and is, of course, freely
611 and readily configurable.</P
620 >1.8. Can Privoxy make mistakes?
621 This does not sound very scientific.</H3
623 > Actually, it's a black art ;-) And yes, it is always possible to have a broad
624 rule accidentally block or change something by mistake. You will almost surely
625 run into such situations at some point. It is tricky writing rules to
626 cover every conceivable possibility, and not occasionally get false positives.</P
628 > But this should not be a big concern since the
632 > configuration is very flexible, and
633 includes tools to help identify these types of situations so they can be
634 addressed as needed, allowing you to customize your installation.
636 HREF="trouble.html#BADSITE"
637 >See the Troubleshooting section below</A
647 >1.9. Will I have to configure Privoxy
648 before I can use it?</H3
650 > No, not really. The default installation should give you a good starting
651 point, and block <SPAN
657 > unwanted content.</P
659 > But 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
672 > You will have to tell your browser about <SPAN
676 (see the Installation section below).</P
685 >1.10. My browser does the same things as
686 Privoxy. Why should I use
689 > Modern browsers do indeed have <SPAN
696 functionality as <SPAN
700 adequate for you. But <SPAN
704 versatile and powerful, and can do a number of things that browsers just can't.
707 > In addition, a proxy is good choice if you use multiple browsers, or
708 have a LAN with multiple computers. This way all the configuration
709 is in one place, and you don't have to maintain a similar configuration
710 for possibly many browsers.
720 >1.11. Why should I trust Privoxy?</H3
722 > The most important reason is because you have access to
729 >, and you can control everything. You can
730 check every line of every configuration file yourself. You can check every
731 last bit of source code should you desire. And even if you can't read code,
732 there should be some comfort in knowing that thousands of other people can,
733 and do read it. You can build the software from scratch, if you want, so
734 that you know the executable is clean, and that it is
741 >. In fact, we encourage this level of scrutiny. It
742 is one reason we use <SPAN
755 >1.12. Is there is a license or fee? What about a
756 warranty? Registration?</H3
761 > is licensed under the <A
762 HREF="http://www.gnu.org/copyleft/gpl.html"
764 >GNU General Public License (GPL)</A
766 It is free to use, copy, modify or distribute as you wish under the terms of this
767 license. Please see the <A
768 HREF="copyright.html"
771 information on the license and copyright. Or the <TT
775 that should be included.
784 > of any kind, expressed, implied or otherwise.
785 That is something that would cost real money ;-) There is no registration either.
806 >1.13. Can Privoxy remove spyware? Adware? Viruses?</H3
811 > cannot remove anything. It is not a removal tool. It is a
815 > can help prevent contact from sites
816 that use such tactics with approriate configuration rules, and thus could
817 conceivably prevent contamination from such sites.</P
826 >1.14. Can I use Privoxy with other ad-blocking software?</H3
831 > should work fine with other proxies and other software in general.</P
833 > But it is probably not necessary to use <SPAN
836 > in conjunction with other
837 ad-blocking products, and this could conceivably cause undesirable results.
838 It would be better to choose one software or the other and work a little to
839 tweak its configuration to your liking.</P
848 >1.15. I would like to help you, what can I do?</H3
856 >1.15.1. Would you like to participate?</H4
864 > need help. There is something for
865 everybody who wants to help us. We welcome new developers, packagers,
866 testers, documentation writers or really anyone with a desire to help in
877 >. There are many other tasks available. In fact,
878 the programmers often can't spend as much time programming because of some
879 of the other, more mundane things that need to be done, like checking the
880 Tracker feedback sections.
884 HREF="https://sourceforge.net/account/register.php"
886 >get an account on SourceForge.net</A
888 and mail your id to the <A
889 HREF="mailto:ijbswa-developers@lists.sourceforge.net"
893 >. Then, please read the <A
894 HREF="../developer-manual/index.html"
896 >Developer's Manual</A
898 the pertinent sections.</P
900 > Once we have added you to the team, you'll have access to the <A
901 HREF="http://sourceforge.net/cvs/?group_id=11118"
905 together we'll find a suitable task for you.</P
912 NAME="JOINTEAM-MONEY"
914 >1.15.2. Contribute!</H4
916 > We, of course, welcome donations and could use money for domain registering,
917 buying software to test <SPAN
920 > with, and, of course,
921 for regular world-wide get-togethers (hahaha). If you enjoy the software and feel
922 like helping us with a donation, just <A
923 HREF="mailto: ijbswa-developers@lists.sourceforge.net"
933 NAME="JOINTEAM-SOFTWARE"
935 >1.15.3. Software</H4
937 > If you are a vendor of a web-related software like a browser, web server
938 or proxy, and would like us to ensure that <SPAN
942 runs smoothly with your product, you might consider supplying us with a
943 copy or license. We can't, however, guarantee that we will fix all potential
944 compatibility issues as a result.</P
953 SUMMARY="Footer navigation table"
982 HREF="installation.html"
992 >Privoxy Frequently Asked Questions</TD