1 Privoxy Frequently Asked Questions
3 Copyright © 2001, 2002 by Privoxy Developers
5 $Id: faq.sgml,v 1.61.2.5 2002/07/26 15:22:58 oes Exp $
8 This FAQ gives quick answers to frequently asked questions about Privoxy . It
9 can't and doesn't replace the User Manual.
11 Privoxy is a web proxy with advanced filtering capabilities for protecting
12 privacy, filtering web page content, managing cookies, controlling access, and
13 removing ads, banners, pop-ups and other obnoxious Internet junk. Privoxy has a
14 very flexible configuration and can be customized to suit individual needs and
15 tastes. Privoxy has application for both stand-alone systems and multi-user
18 Privoxy is based on Internet Junkbuster (tm).
20 You can find the latest version of the document at http://www.privoxy.org/faq/.
21 Please see the Contact section if you want to contact the developers.
23 -------------------------------------------------------------------------------
25 1. General Information
26 1.1. What is this new version of Privoxy?
27 1.2. Why "Privoxy"? Why a name change at all?
28 1.3. How does Privoxy differ from the old Junkbuster?
29 1.4. What is a "proxy"? How does Privoxy work?
30 1.5. How does Privoxy know what is an ad, and what is not?
31 1.6. Can Privoxy make mistakes? This does not sound very scientific.
32 1.7. My browser does the same things as Privoxy. Why should I use Privoxy
34 1.8. Is there is a license or fee? What about a warranty? Registration?
35 1.9. I would like to help you, what do I do?
36 1.9.1. Money Money Money
38 1.9.3. You want to work with us?
44 2.1. Which browsers are supported by Privoxy?
45 2.2. Which operating systems are supported?
46 2.3. Can I install Privoxy over Junkbuster?
47 2.4. I just installed Privoxy. Is there anything special I have to do now?
48 2.5. What is the proxy address of Privoxy?
49 2.6. I just installed Privoxy, and nothing is happening. All the ads are
54 3.1. Where can I get updated Actions Files?
55 3.2. Can I use my old config files?
56 3.3. What is an "actions" file?
57 3.4. The "actions" concept confuses me. Please list some of these "actions"
59 3.5. How are actions files configured? What is the easiest way to do this?
60 3.6. There are several different "actions" files. What are the differences?
61 3.7. How can I make my Yahoo/Hotmail/GMX account work?
62 3.8. What's the difference between the "Cautious", "Medium" and "Advanced"
64 3.9. Why can I change the configuration with a browser? Does that not raise
66 3.10. What is the default.filter file? What is a "filter"?
67 3.11. How can I set up Privoxy to act as a proxy for my LAN?
68 3.12. Instead of ads, now I get a checkerboard pattern. I don't want to see
70 3.13. Why would anybody want to see a checkerboard pattern?
71 3.14. I see some images being replaced by a text instead of the
72 checkerboard image. Why and how do I get rid of this?
73 3.15. Can Privoxy run as a service on Win2K/NT?
74 3.16. How can I make Privoxy work with other proxies like Squid?
75 3.17. Can Privoxy run as a "transparent" proxy?
79 4.1. How much does Privoxy slow my browsing down? This has to add extra
81 4.2. I noticed considerable delays in page requests compared to the old
82 Junkbuster. What's wrong?
83 4.3. What are "http://config.privoxy.org/" and "http://p.p/"?
84 4.4. Do you still maintain the blocklists?
85 4.5. How can I submit new ads?
86 4.6. How can I hide my IP address?
87 4.7. Can Privoxy guarantee I am anonymous?
88 4.8. Might some things break because header information or content is being
90 4.9. Can Privoxy act as a "caching" proxy to speed up web browsing?
91 4.10. What about as a firewall? Can Privoxy protect me?
92 4.11. I have large empty spaces / a checkerboard pattern now where ads used
94 4.12. How can Privoxy filter Secure (HTTPS) URLs?
95 4.13. Privoxy runs as a "server". How secure is it? Do I need to take any
97 4.14. How can I temporarily disable Privoxy?
98 4.15. When "disabled" is Privoxy totally out of the picture?
99 4.16. Where can I find more information about Privoxy and related issues?
103 5.1. I just upgraded and am getting "connection refused" with every web
105 5.2. I just added a new rule, but the steenkin ad is still getting through.
107 5.3. One of my favorite sites does not work with Privoxy. What can I do?
108 5.4. After installing Privoxy, I have to log in every time I start IE. What
110 5.5. I cannot connect to any FTP sites. Privoxy seems to be blocking me.
113 6. Contacting the developers, Bug Reporting and Feature Requests
116 6.3. Request New Features
117 6.4. Report Ads or Other Actions-Related Problems
121 7. Privoxy Copyright, License and History
127 1. General Information
129 1.1. What is this new version of Privoxy?
131 In the beginning, there was the Internet Junkbuster, by Anonymous Coders and
132 Junkbusters Corporation. It saved many users a lot of pain in the early days of
133 web advertising and user tracking.
135 But the web, its protocols and standards, and with it, the techniques for
136 forcing users to consume ads, give up autonomy over their browsing, and for
137 spying on them, kept evolving. Unfortunately, the Internet Junkbuster did not.
138 Version 2.0.2, published in 1998, was (and is) the last official release
139 available from Junkbusters Corporation. Fortunately, it had been released under
140 the GNU GPL, which allowed further development by others.
142 So Stefan Waldherr started maintaining an improved version of the software, to
143 which eventually a number of people contributed patches. It could already
144 replace banners with a transparent image, and had a first version of pop-up
145 killing, but it was still very closely based on the original, with all its
146 limitations, such as the lack of HTTP/1.1 support, flexible per-site
147 configuration, or content modification. The last release from this effort was
148 version 2.0.2-10, published in 2000.
150 Then, some developers picked up the thread, and started turning the software
151 inside out, upside down, and then reassembled it, adding many new features
154 The result of this is Privoxy, whose first stable release, 3.0, is due in June
156 -------------------------------------------------------------------------------
158 1.2. Why "Privoxy"? Why a name change at all?
160 Privoxy is the "Privacy Enhancing Proxy". Also, its content modification and
161 junk suppression allow you to browse your "private edition" of the web.
163 Junkbusters Corporation continues to offer their original version of the
164 Internet Junkbuster, so publishing our Junkbuster-derived software under the
165 same name led to confusion.
167 There are also potential legal complications from the continued use of the
168 Junkbuster name, which is a registered trademark of Junkbusters Corporation.
169 There are, however, no objections from Junkbusters Corporation to the Privoxy
170 project itself, and they, in fact, still share our ideals and goals.
172 The developers also believed that there are so many changes from the original
173 code, that it was time to make a clean break from the past and make a name in
174 their own right, especially now with the pending release of version 3.0.
175 -------------------------------------------------------------------------------
177 1.3. How does Privoxy differ from the old Junkbuster?
179 Privoxy picks up where Junkbuster left off. All the old features remain. The
180 new Privoxy still blocks ads and banners, still manages cookies, and still
181 helps protect your privacy. But, these are all enhanced, and many new features
182 have been added, all in the same vein.
184 The configuration has changed significantly as well. This is something that
185 users will notice right off the bat if upgrading from Junkbuster 2.0.x. The
186 "blocklist" "cookielist", "imagelist" and much more has been combined into the
187 "actions" files, with a completely different syntax. See the note to upgraders
190 Privoxy's new features include:
192 * Integrated browser based configuration and control utility at http://
193 config.privoxy.org/ (shortcut: http://p.p/). Browser-based tracing of rule
194 and filter effects. Remote toggling.
196 * Web page content filtering (removes banners based on size, invisible
197 "web-bugs", JavaScript and HTML annoyances, pop-up windows, etc.)
199 * Modularized configuration that allows for standard settings and user
200 settings to reside in separate files, so that installing updated actions
201 files won't overwrite individual user settings.
203 * HTTP/1.1 compliant (but not all optional 1.1 features are supported).
205 * Support for Perl Compatible Regular Expressions in the configuration files,
206 and generally a more sophisticated and flexible configuration syntax over
209 * Improved cookie management features (e.g. session based cookies).
213 * Bypass many click-tracking scripts (avoids script redirection).
215 * Multi-threaded (POSIX and native threads).
217 * User-customizable HTML templates for all proxy-generated pages (e.g.
220 * Auto-detection and re-reading of config file changes.
222 * Improved signal handling, and a true daemon mode (Unix).
224 * Every feature now controllable on a per-site or per-location basis,
225 configuration more powerful and versatile over-all.
227 * Many smaller new features added, limitations and bugs removed, and security
231 -------------------------------------------------------------------------------
232 1.4. What is a "proxy"? How does Privoxy work?
234 A web proxy is a service, based on a software such as Privoxy, that clients
235 (i.e. browsers) can use instead of connecting directly to the web servers on
236 the Internet. The clients then ask the proxy to fetch the objects they need
237 (web pages, images, movies etc) on their behalf, and when the proxy has done
238 so, it hands the results back to the client.
240 There are many reasons to use web proxies, such as security (firewalling),
241 efficiency (caching) and others, and there are just as many different proxies
242 to accommodate those needs.
244 Privoxy is a proxy that is solely focused on privacy protection and junk
245 elimination. Sitting between your browser(s) and the Internet, it is in a
246 perfect position to filter outbound personal information that your browser is
247 leaking, as well as inbound junk. It uses a variety of techniques to do this,
248 all of which are under your control via the various configuration files and
250 -------------------------------------------------------------------------------
252 1.5. How does Privoxy know what is an ad, and what is not?
254 Privoxy's approach to blocking ads is twofold:
256 First, there are certain patterns in the locations (URLs) of banner images.
257 This applies to both the path (you wouldn't guess how many web sites serve
258 their banners from a directory called "banners"!) and the host (blocking the
259 big banner hosting services like doublecklick.net already helps a lot). Privoxy
260 takes advantage of this fact by using URL patterns to sort out and block the
261 requests for banners.
263 Second, banners tend to come in certain sizes. But you can't tell the size of
264 an image by its URL without downloading it, and if you do, it's too late to
265 save bandwidth. Therefore, Privoxy also inspects the HTML sources of web pages
266 while they are loaded, and replaces references to images with standard banner
267 sizes by dummy references, so that your browser doesn't request them anymore in
270 Both of this involves a certain amount of guesswork and is, of course, freely
272 -------------------------------------------------------------------------------
274 1.6. Can Privoxy make mistakes? This does not sound very scientific.
276 Actually, it's a black art ;-) And yes, it is always possible to have a broad
277 rule accidentally block or change something by mistake. There is a good chance
278 you may run into such a situation at some point. It is tricky writing rules to
279 cover every conceivable possibility, and not occasionally get false positives.
281 But this should not be a big concern since the Privoxy configuration is very
282 flexible, and includes tools to help identify these types of situations so they
283 can be addressed as needed, allowing you to customize your installation. (See
284 the Troubleshooting section below.)
285 -------------------------------------------------------------------------------
287 1.7. My browser does the same things as Privoxy. Why should I use Privoxy at
290 Modern browsers do indeed have some of the same functionality as Privoxy. Maybe
291 this is adequate for you. But Privoxy is much more versatile and powerful, and
292 can do a number of things that browsers just can't.
294 In addition, a proxy is good choice if you use multiple browsers, or have a LAN
295 with multiple computers. This way all the configuration is in one place, and
296 you don't have to maintain a similar configuration for possibly many browsers.
297 -------------------------------------------------------------------------------
299 1.8. Is there is a license or fee? What about a warranty? Registration?
301 Privoxy is licensed under the GNU General Public License (GPL). It is free to
302 use, copy, modify or distribute as you wish under the terms of this license.
303 Please see the Copyright section for more information on the license and
304 copyright. Or the LICENSE file that should be included.
306 There is no warranty of any kind, expressed, implied or otherwise. That is
307 something that would cost real money ;-) There is no registration either.
308 Privoxy really is free in every respect!
309 -------------------------------------------------------------------------------
311 1.9. I would like to help you, what do I do?
313 1.9.1. Money Money Money
315 We, of course, welcome donations and could use money for domain registering,
316 buying software to test Privoxy with, and, of course, for regular world-wide
317 get-togethers (hahaha). If you enjoy the software and feel like helping us with
318 a donation, just drop us a note.
319 -------------------------------------------------------------------------------
323 If you are a vendor of a web-related software like a browser, web server or
324 proxy, and would like us to ensure that Privoxy runs smoothly with your
325 product, you might consider supplying us with a copy or license. We can't,
326 however, guarantee that we will fix all potential compatibility issues as a
328 -------------------------------------------------------------------------------
330 1.9.3. You want to work with us?
332 Well, helping the team is always a good idea. We welcome new developers,
333 packaging gurus or documentation writers. Simply get an account on
334 SourceForge.net and mail your id to the developers mailing list. Then read the
337 Once we have added you to the team, you'll have write access to the CVS
338 repository, and together we'll find a suitable task for you.
339 -------------------------------------------------------------------------------
343 2.1. Which browsers are supported by Privoxy?
345 Any browser that can be configured to use a proxy, which should be virtually
346 all browsers. Direct browser support is not necessary since Privoxy runs as a
347 separate application and talks to the browser in the standardized HTTP
348 protocol, just like a web server does.
349 -------------------------------------------------------------------------------
351 2.2. Which operating systems are supported?
353 At present, Privoxy is known to run on Windows(95, 98, ME, 2000, XP), Linux
354 (RedHat, SuSE, Debian, Conectiva), Mac OSX, OS/2, AmigaOS, BeOS, FreeBSD,
355 NetBSD, Solaris, and many more flavors of Unix.
357 But any operating system that runs TCP/IP, can conceivably take advantage of
358 Privoxy in a networked situation where Privoxy would run as a server on a LAN
359 gateway. Then only the "gateway" needs to be running one of the above operating
362 Source code is freely available, so porting to other operating systems is
363 always a possibility.
364 -------------------------------------------------------------------------------
366 2.3. Can I install Privoxy over Junkbuster?
368 We recommend you un-install Junkbuster first to minimize conflicts and
369 confusion. You may want to save your old configuration files for future
370 reference. The configuration files and syntax have substantially changed, so
371 you will need to manually port your old patterns. See the note to upgraders and
372 installation chapter in the user manual for details.
374 Note: Some installers may automatically un-install Junkbuster, if present!
375 -------------------------------------------------------------------------------
377 2.4. I just installed Privoxy. Is there anything special I have to do now?
379 All browsers must be told to use Privoxy as a proxy by specifying the correct
380 proxy address and port number in the appropriate configuration area for the
381 browser. See below. You should also flush your browser's memory and disk cache
382 to get rid of any cached junk items.
383 -------------------------------------------------------------------------------
385 2.5. What is the proxy address of Privoxy?
387 If you set up the Privoxy to run on the computer you browse from (rather than
388 your ISP's server or some networked computer on a LAN), the proxy will be on
389 127.0.0.1 (sometimes referred to as "localhost", which is the special name used
390 by every computer on the Internet to refer to itself) and the port will be 8118
391 (unless you have Privoxy to run on a different port with the listen-address
394 When configuring your browser's proxy settings you typically enter the word
395 "localhost" or the IP address "127.0.0.1" in the boxes next to "HTTP" and
396 "Secure" (HTTPS) and then the number "8118" for "port". This tells your browser
397 to send all web requests to Privoxy instead of directly to the Internet.
399 Privoxy can also be used to proxy for a Local Area Network. In this case, your
400 would enter either the IP address of the LAN host where Privoxy is running, or
401 the equivalent hostname. Port assignment would be same as above. Note that
402 Privoxy doesn't listen on any LAN interfaces by default.
404 Privoxy does not currently handle protocols such as FTP, SMTP, IM, IRC, ICQ, or
405 other Internet protocols.
406 -------------------------------------------------------------------------------
408 2.6. I just installed Privoxy, and nothing is happening. All the ads are there.
411 Did you configure your browser to use Privoxy as a proxy? It does not sound
412 like it. See above. You might also try flushing the browser's caches to force a
413 full re-reading of pages. You can verify that Privoxy is running, and your
414 browser is correctly configured by entering the special URL: http://
415 config.privoxy.org/. This should take you to a page titled "This is Privoxy.."
416 with access to Privoxy's internal configuration. If you see this, then you are
417 good to go. If you receive a page saying "Privoxy is not running", then the
418 browser is not set up to use your Privoxy installation. If you receive anything
419 else (probably nothing at all), it could either be that the browser is not set
420 up correctly, or that Privoxy is not running at all. Check the log file.
421 -------------------------------------------------------------------------------
425 3.1. Where can I get updated Actions Files?
427 Based on your feedback and the continuing development, updated actions files
428 will be made available on the files section of our project page.
430 If you wish to receive an email notification whenever we release updates of
431 Privoxy or the actions file, subscribe to our announce mailing list,
432 ijbswa-announce@lists.sourceforge.net.
433 -------------------------------------------------------------------------------
435 3.2. Can I use my old config files?
437 The syntax, number, and purpose of configuration files has substantially
438 changed from Junkbuster and earlier versions of Privoxy. The old files, like
439 blocklist will not work at all. If you are upgrading from a 2.0.x version, you
440 will need to port your configuration data to the new format. Note that even the
441 pattern syntax has changed! Even configuration files from the 2.9.x versions
442 will need to be adapted, as configuration syntax has been very much in flow in
444 -------------------------------------------------------------------------------
446 3.3. What is an "actions" file?
448 Actions files are where various actions that Privoxy might take while
449 processing a certain request, are configured. Typically, you would define a set
450 of default actions that apply to all URLs, then add exceptions to these
451 defaults where needed.
453 Actions can be defined on a URL pattern basis, i.e. for single URLs, whole web
454 sites, groups or parts thereof etc. Actions can also be grouped together and
455 then applied to requests matching one or more patterns. There are many possible
456 actions that might apply to any given site. As an example, if you are blocking
457 cookies as one of your default actions, but need to accept cookies from a given
458 site, you would need to define an exception for this site in one of your
459 actions files, preferably in user.action
460 -------------------------------------------------------------------------------
462 3.4. The "actions" concept confuses me. Please list some of these "actions".
464 For a comprehensive discussion of the actions concept, please refer to the
465 actions file chapter in the user manual. It includes a list of all actions and
466 an actions file tutorial to get you started.
467 -------------------------------------------------------------------------------
469 3.5. How are actions files configured? What is the easiest way to do this?
471 Actions files are just text files in a special syntax and can be edited with a
472 text editor. The probably easiest way is to access Privoxy's user interface
473 with your web browser at http://config.privoxy.org/ (Shortcut: http://p.p/) and
474 then select "View & change the current configuration" from the menu.
475 -------------------------------------------------------------------------------
477 3.6. There are several different "actions" files. What are the differences?
479 As of Privoxy v2.9.15, three actions files are being included, to be used for
480 different purposes: These are default.action, the "main" actions file which is
481 actively maintained by the Privoxy developers, user.action, where users are
482 encouraged to make their private customizations, and standard.action, which is
483 for internal Privoxy use only. Please see the actions chapter in the user
484 manual for a more detailed explanation.
486 Earlier versions included three different versions of the default.action file.
487 The new scheme allows for greater flexibility of local configuration, and for
488 browser based selection of pre-defined "aggressiveness" levels.
489 -------------------------------------------------------------------------------
491 3.7. How can I make my Yahoo/Hotmail/GMX account work?
493 The default configuration shouldn't impact the usability of any of these
494 services. It will, however, make all cookies temporary, so that your browser
495 will forget your login credentials in between browser sessions. If you would
496 like not to have to log in manually each time you access those websites, simply
497 turn off all cookie handling for them in the user.action file. An example for
498 yahoo might look like:
500 # Allow all cookies for Yahoo login:
502 { -crunch-incoming-cookies -crunch-outgoing-cookies -session-cookies-only }
504 -------------------------------------------------------------------------------
506 3.8. What's the difference between the "Cautious", "Medium" and "Advanced"
509 Configuring Privoxy is not entirely trivial. To help you get started, we
510 provide you with three different default action "packages" in the web based
511 actions file editor at http://config.privoxy.org/show-status. The following
512 table shows you, which of the most important features are enabled in each
515 Table 1. Default Configurations
516 +-------------------+------------------+-------------------+------------------+
517 |Feature |Cautious |Intermadiate |Advanced |
518 +-------------------+------------------+-------------------+------------------+
519 |Ad-blocking by URL |yes |yes |yes |
520 +-------------------+------------------+-------------------+------------------+
521 |Ad-filtering by |yes |yes |yes |
523 +-------------------+------------------+-------------------+------------------+
524 |GIF de-animation |no |yes |yes |
525 +-------------------+------------------+-------------------+------------------+
526 |Referer forging |no |yes |yes |
527 +-------------------+------------------+-------------------+------------------+
528 |Cookie handling |none |session-only |kill |
529 +-------------------+------------------+-------------------+------------------+
530 |Pop-up killing |no |yes |yes |
531 +-------------------+------------------+-------------------+------------------+
532 |Fast redirects |no |no |yes |
533 +-------------------+------------------+-------------------+------------------+
534 |HTML taming |yes |yes |yes |
535 +-------------------+------------------+-------------------+------------------+
536 |JavaScript taming |yes |yes |yes |
537 +-------------------+------------------+-------------------+------------------+
538 |Web-bug killing |yes |yes |yes |
539 +-------------------+------------------+-------------------+------------------+
540 |Fun text |no |no |yes |
541 |replacements | | | |
542 +-------------------+------------------+-------------------+------------------+
543 |Image tag |no |no |yes |
545 +-------------------+------------------+-------------------+------------------+
546 |Ad-filtering by |no |no |yes |
548 +-------------------+------------------+-------------------+------------------+
550 Where the defaults are likely to break some sites, exceptions for known popular
551 "problem" sites are included, but in general, the more aggressive your default
552 settings are, the more exceptions you will have to make later. See the user
553 manual for a more deatiled discussion.
554 -------------------------------------------------------------------------------
556 3.9. Why can I change the configuration with a browser? Does that not raise
559 It may seem strange that regular users can edit the config files with their
560 browsers, although the whole /etc/privoxy hierarchy belongs to the user
561 "privoxy", with only 644 permissions.
563 When you use the browser-based editor, Privoxy itself is writing to the config
564 files. Because Privoxy is running as the user "privoxy", it can update the
567 If you run Privoxy for multiple untrusted users (e.g. in a LAN), you will
568 probably want to turn the web-based editor and remote toggle features off by
569 setting "enable-edit-actions 0" and "enable-remote-toggle 0" in the main
572 Note that in the default configuration, only local users (i.e. those on
573 "localhost") can connect to Privoxy, so this is not (normally) a security
575 -------------------------------------------------------------------------------
577 3.10. What is the default.filter file? What is a "filter"?
579 The default.filter file is where filters are defined, which can be used to
580 modify or remove, web page content on the fly. Filters apply to anything in the
581 page source, including HTML tags, and JavaScript. Regular expressions are used
582 to accomplish this. There are a number of pre-defined filters to deal with
583 common annoyances. The filters are only defined here, to invoke them, you need
584 to use the filter action in one of the actions files. Filtering is
585 automatically disabled for inappropriate MIME types.
587 If you are familiar with regular expressions, and HTML, you can look at the
588 provided default.filter with a text editor and define your own filters. This is
589 potentially a very powerful feature, but requires some expertise in both
590 regular expressions and HTML/HTTP.
592 Presently, there is no GUI editor option for this part of the configuration,
593 but you can disable/enable the various pre-defined filters of the included
594 default.filter file with the web-based actions file editor.
595 -------------------------------------------------------------------------------
597 3.11. How can I set up Privoxy to act as a proxy for my LAN?
599 By default, Privoxy only responds to requests from 127.0.0.1 (localhost). To
600 have it act as a server for a network, this needs to be changed in the main
601 configuration file. Look for the listen-address option, which may be commented
602 out with a "#" symbol. Make sure it is uncommented, and assign it the address
603 of the LAN gateway interface, and port number to use. Assuming your LAN address
604 is 192.168.1.1 and you wish to run Privoxy on port 8118, this line schould look
607 listen-address 192.168.1.1:8118
609 Save the file, and restart Privoxy. Configure all browsers on the network then
610 to use this address and port number.
612 If you run Privoxy on a LAN with untrusted users, we recommend that you
613 double-check the access control and security options!
614 -------------------------------------------------------------------------------
616 3.12. Instead of ads, now I get a checkerboard pattern. I don't want to see
619 The replacement for blocked images can be controlled with the set-image-blocker
620 action. You have the choice of a checkerboard pattern, a transparent 1x1 GIF
621 image (aka "blank"), or a redirect to a custom image of your choice. Note that
622 this choice only has effect for images which are blocked as images, i.e. whose
623 URLs match both a handle-as-image and block action.
625 If you want to see nothing, then change the set-image-blocker action to "blank"
626 . This can be done by editing the default.action file, or trough the web-based
628 -------------------------------------------------------------------------------
630 3.13. Why would anybody want to see a checkerboard pattern?
632 Remember that telling which image is an ad and which isn't, is mostly
633 guesswork. While we hope that the standard configuration is rather smart, it
634 can and will make errors. The checkerboard image is visually decent, but it
635 shows you that and where images were blocked, which can be very helpful in case
636 some navigation aid or otherwise innocent image was erraneously blocked. Some
637 people might also enjoy seeing how many banners they don't have to see..
638 -------------------------------------------------------------------------------
640 3.14. I see some images being replaced by a text instead of the checkerboard
641 image. Why and how do I get rid of this?
643 This happens when the banners are not embedded in the HTML code of the page
644 itself, but in separate HTML (sub)documents that are loaded into (i)frames or
645 (i)layers, and these external HTML documents are blocked. Being non-images they
646 get replaced by a substitute HTML page rather than a substitute image, which
647 wouldn't work out technically, since the browser expects and accepts only HTML
648 when it has requested an HTML document.
650 The substitute page adapts to the available space and shows itself as a
651 miniature two-liner if loaded into small frames, or full-blown with a large red
652 "BLOCKED" banner if space allows.
654 If you prefer the banners to be blocked by images, you must see to it that the
655 HTML documents in which they are embedded are not blocked. Clicking the "See
656 why" link offered in the substitute page will show you which rule blocked the
657 page. After changing the rule and un-blocking the HTML documents, the browser
658 will try to load the actual banner images and the usual image blocking will
659 (hopefully!) kick in.
660 -------------------------------------------------------------------------------
662 3.15. Can Privoxy run as a service on Win2K/NT?
664 Yes, it can run as a system service using srvany.exe. The only catch is that
665 this will effectively disable the Privoxy icon (and its menu!) in the taskbar.
666 You can have one or the other, but not both at this time :(
668 There is a pending feature request for this functionality. See the discussion
669 at http://sourceforge.net/tracker/?func=detail&atid=361118&aid=485617&group_id=
670 11118, for details, and a sample configuration.
671 -------------------------------------------------------------------------------
673 3.16. How can I make Privoxy work with other proxies like Squid?
675 This can be done and is often useful to combine the benefits of Privoxy with
676 those of a caching proxy. See the forwarding chapter in the user manual which
677 describes how to do this.
678 -------------------------------------------------------------------------------
680 3.17. Can Privoxy run as a "transparent" proxy?
682 No, Privoxy currently does not have this ability, though it is planned for a
683 future release. Transparent proxies require special handling of the request
684 headers beyond what Privoxy is now capable of.
686 Chaining Privoxy behind another proxy that has this ability should work though.
687 See the forwarding chapter in the user manual. As a transparent proxy to be
688 used for chaining we recommend Transproxy (http://www.transproxy.nlc.net.au/).
689 -------------------------------------------------------------------------------
693 4.1. How much does Privoxy slow my browsing down? This has to add extra time to
696 It should not slow you down any in real terms, and may actually help speed
697 things up since ads, banners and other junk are not being displayed. The actual
698 processing time required by Privoxy itself for each page, is relatively small
699 in the overall scheme of things, and happens very quickly. This is typically
700 more than offset by time saved not downloading and rendering ad images.
702 "Filtering" content via the filter or deanimate-gifs actions may cause a
703 perceived slowdown, since the entire document needs to be buffered before
704 displaying. See below.
705 -------------------------------------------------------------------------------
707 4.2. I noticed considerable delays in page requests compared to the old
708 Junkbuster. What's wrong?
710 If you use any filter action, such as filtering banners by size, web-bugs etc,
711 or the deanimate-gifs action, the entire document must be loaded into memory in
712 order for the filtering mechanism to work, and nothing is sent to the browser
715 The loading time does not really change in real numbers, but the feeling is
716 different, because most browsers are able to start rendering incomplete
717 content, giving the user a feeling of "it works". This effect is especially
718 noticeable on slow dialup connections.
720 Filtering is automatically disabled for inappropriate MIME types.
721 -------------------------------------------------------------------------------
723 4.3. What are "http://config.privoxy.org/" and "http://p.p/"?
725 http://config.privoxy.org/ is the address of Privoxy's built-in user interface,
726 and http://p.p/ is a shortcut for it.
728 Since Privoxy sits between your web browser and the Internet, it can simply
729 intercept requests for these addresses and answer them with its built-in "web
732 This also makes for a good test for your browser configuration: If entering the
733 URL http://config.privoxy.org/ takes you to a page saying "This is Privoxy..",
734 everything is OK. If you get a page saying "Privoxy is not working" instead,
735 then your browser didn't use Privoxy for the request, hence it could not be
736 intercepted, and you have accessed the real web site at config.privoxy.org.
738 With recent versions of Privoxy (version 2.9.x and later), the user interface
739 features information on the run time status, the configuration, and even a
740 built-in editor for the actions files.
742 Note that the built-in URLs from earlier versions of Junkbuster / Privoxy,
743 http://example.com/show-proxy-args and http://i.j.b/, are no longer supported.
744 If you still use such an old version, you should really consider upgrading to
746 -------------------------------------------------------------------------------
748 4.4. Do you still maintain the blocklists?
750 No. The patterns for blocking now reside (among other things) in the actions
751 files, which are actively maintained instead. See next question ...
752 -------------------------------------------------------------------------------
754 4.5. How can I submit new ads?
756 Yes, absolutely! Please see the Contact section for how to do that. Please note
757 that you (technically) need the latest Privoxy version for this to work.
758 -------------------------------------------------------------------------------
760 4.6. How can I hide my IP address?
762 If you run both the browser and the proxy locally, you cannot hide your IP
763 address with Privoxy or any other software. The server needs to know your IP
764 address to send the answers back to you.
766 Fortunately there are many publicly usable anonymous proxies out there, which
767 solve the problem by providing a further level of indirection between you and
768 the web server, shared by many people, and thus letting your requests "drown"
769 in white noise of unrelated requests as far as user tracking is concerned.
771 Most of them will, however, log your IP address and make it available to the
772 authorities in case you abuse that anonymity for criminal purposes. In fact you
773 can't even rule out that some of them only exist to *collect* information on
774 (those suspicious) people with a more than average preference for privacy.
776 You can find a list of anonymous public proxies at multiproxy.org and many more
777 through Google. A particularly interesting project is the JAP service offered
778 by the Technical University of Dresden (http://anon.inf.tu-dresden.de/
781 There is, however, even in the single-machine case the possibility to make the
782 server believe that your machine is in fact a shared proxy serving a whole big
783 LAN, and we are looking into that.
784 -------------------------------------------------------------------------------
786 4.7. Can Privoxy guarantee I am anonymous?
788 No. Your chances of remaining anonymous are greatly improved, but unless you
789 are an expert on Internet security it would be safest to assume that everything
790 you do on the Web can be traced back to you.
792 Privoxy can remove various information about you, and allows you more freedom
793 to decide which sites you can trust, and what details you want to reveal. But
794 it's still possible that web sites can find out who you are. Here's one way
797 A few browsers disclose the user's email address in certain situations, such as
798 when transferring a file by FTP. Privoxy does not filter FTP. If you need this
799 feature, or are concerned about the mail handler of your browser disclosing
800 your email address, you might consider products such as NSClean.
802 Browsers available only as binaries could use non-standard headers to give out
803 any information they can have access to: see the manufacturer's license
804 agreement. It's impossible to anticipate and prevent every breach of privacy
805 that might occur. The professionally paranoid prefer browsers available as
806 source code, because anticipating their behavior is easier. Trust the source,
808 -------------------------------------------------------------------------------
810 4.8. Might some things break because header information or content is being
813 Definitely. More and more sites use HTTP header content to decide what to
814 display and how to display it. There is many ways that this can be handled, so
815 having hard and fast rules, is tricky.
817 "User-Agent" in particular is often used in this way to identify the browser,
818 and adjust content accordingly. Changing this now (at least not further than
819 removing the OS information) is not recommended, since so many sites do look
820 for it. You may get undesirable results by changing this.
822 For instance, different browsers use different encodings of Russian and Czech
823 characters, certain web servers convert pages on-the-fly according to the User
824 Agent header. Giving a "User Agent" with the wrong operating system or browser
825 manufacturer causes some sites in these languages to be garbled; Surfers to
826 Eastern European sites should change it to something closer. And then some page
827 access counters work by looking at the "Referer" header; they may fail or break
828 if unavailable. The weather maps of Intellicast have been blocked by their
829 server when no "Referer" or cookie is provided, is another example. (But you
830 can forge both headers without giving information away). There are many other
831 ways things can go wrong when trying to fool a web server.
833 Similar thoughts apply to modifying JavaScript, and, to a lesser degree, HTML
836 If you have problems with a site, you will have to adjust your configuration
837 accordingly. Cookies are probably the most likely adjustment that may be
838 required, but by no means the only one.
839 -------------------------------------------------------------------------------
841 4.9. Can Privoxy act as a "caching" proxy to speed up web browsing?
843 No, it does not have this ability at all. You want something like Squid for
844 this. And, yes, before you ask, Privoxy can co-exist with other kinds of
845 proxies like Squid. See the forwarding chapter in the user manual for details.
846 -------------------------------------------------------------------------------
848 4.10. What about as a firewall? Can Privoxy protect me?
850 Not in the way you mean, or in the way a true firewall can. Privoxy can help
851 protect your privacy, but not protect you from intrusion attempts. It is, of
852 course, perfectly possible and recommended to use both.
853 -------------------------------------------------------------------------------
855 4.11. I have large empty spaces / a checkerboard pattern now where ads used to
858 It would be technically possible eliminate the banners in a way that frees
859 their screen estate in many cases, by doing all banner blocking with filters,
860 i.e. eliminating the whole image references from the HTML pages instead of
861 letting them stay in, and blocking the resulting requests for the banners
864 But this would consume considerable CPU resources, would likely destroy the
865 layout of many web pages which rely on the banners consuming a certain amount
866 of screen space, and would fail in other cases, where the screen space is
867 reserved e.g. by tables anyway. Also, making the banners disappear without a
868 visual trace complicates troubleshooting.
870 So we won't support this in the default configuration, but you can of course
871 define appropriate filters yourself.
872 -------------------------------------------------------------------------------
874 4.12. How can Privoxy filter Secure (HTTPS) URLs?
876 Since secure HTTP connections are encrypted SSL sessions between your browser
877 and the secure site, and are meant to be reliably secure, there is little that
878 Privoxy can do but hand the raw gibberish data though from one end to the other
881 The only exception to this is blocking by host patterns, as the client needs to
882 tell Privoxy the name of the remote server, so that Privoxy can establish the
883 connection. If that name matches a host-only pattern, the connection will be
886 As far as ad blocking is concerned, this is less of a restriction than it may
887 seem, since ad sources are often identifiable by the host name, and often the
888 banners to be placed in an encrypted page come unencrypted nonetheless for
889 efficiency reasons, which exposes them to the full power of Privoxy's ad
891 -------------------------------------------------------------------------------
893 4.13. Privoxy runs as a "server". How secure is it? Do I need to take any
896 There are no known exploits that might affect Privoxy. On Unix-like systems,
897 Privoxy can run as a non-privileged user, which is how we recommend it be run.
898 Also, by default Privoxy only listens to requests from "localhost" only. The
899 server aspect of Privoxy is not itself directly exposed to the Internet in this
900 configuration. If you want to have Privoxy serve as a LAN proxy, this will have
901 to be opened up to allow for LAN requests. In this case, we'd recommend you
902 specify only the LAN gateway address, e.g. 192.168.1.1, in the main Privoxy
903 configuration file and check all access control and security options. All LAN
904 hosts can then use this as their proxy address in the browser proxy
905 configuration, but Privoxy will not listen on any external interfaces. ACLs can
906 be defined in addition, and using a firewall is always good too. Better safe
908 -------------------------------------------------------------------------------
910 4.14. How can I temporarily disable Privoxy?
912 The easiest way is to access Privoxy with your browser by using the remote
913 toggle URL: http://config.privoxy.org/toggle. See the Bookmarklets section of
914 the User Manual for an easy way to access this feature.
915 -------------------------------------------------------------------------------
917 4.15. When "disabled" is Privoxy totally out of the picture?
919 No, this just means all filtering and actions are disabled. Privoxy is still
920 acting as a proxy, but just not doing any of the things that Privoxy would
921 normally be expected to do. It is still a "middle-man" in the interaction
922 between your browser and web sites.
923 -------------------------------------------------------------------------------
925 4.16. Where can I find more information about Privoxy and related issues?
927 Other references and sites of interest to Privoxy users:
929 http://www.privoxy.org/, the Privoxy Home page.
931 http://www.privoxy.org/faq/, the Privoxy FAQ.
933 http://sourceforge.net/projects/ijbswa/, the Project Page for Privoxy on
936 http://config.privoxy.org/, the web-based user interface. Privoxy must be
937 running for this to work. Shortcut: http://p.p/
939 http://www.privoxy.org/actions/, to submit "misses" to the developers.
941 http://www.junkbusters.com/ht/en/cookies.html, an explanation how cookies are
942 used to track web users.
944 http://www.junkbusters.com/ijb.html, the original Internet Junkbuster.
946 http://www.waldherr.org/junkbuster/, Stefan Waldherr's version of Junkbuster,
947 from which Privoxy was derived.
949 http://privacy.net/analyze/, a useful site to check what information about you
950 is leaked while you browse the web.
952 http://www.squid-cache.org/, a very popular caching proxy, which is often used
953 together with Privoxy.
955 http://www.privoxy.org/developer-manual/, the Privoxy developer manual.
957 -------------------------------------------------------------------------------
960 5.1. I just upgraded and am getting "connection refused" with every web page?
962 Either Privoxy is not running, or your browser is configured for a different
963 port than what Privoxy is using.
965 The old Privoxy (and also Junkbuster) used port 8000 by default. This has been
966 changed to port 8118 now, due to a conflict with NAS (Network Audio Service),
967 which uses port 8000. If you haven't, you need to change your browser to the
968 new port number, or alternately change the listen-address option in Privoxy's
969 main configuration file.
970 -------------------------------------------------------------------------------
972 5.2. I just added a new rule, but the steenkin ad is still getting through.
975 If the ad had been displayed before you added its URL, it will probably be held
976 in the browser's cache for some time, so it will be displayed without the need
977 for any request to the server, and Privoxy will not be in the picture. The best
978 thing to do is try flushing the browser's caches. And then try again.
980 If this doesn't help, you probably have an error in the rule you applied. Try
981 pasting the full URL of the offending ad into http://config.privoxy.org/
982 show-url-info and see if it really matches your new rule.
983 -------------------------------------------------------------------------------
985 5.3. One of my favorite sites does not work with Privoxy. What can I do?
987 First verify that it is indeed a Privoxy problem, by toggling off Privoxy
988 through http://config.privoxy.org/toggle, and then shift-reloading the problem
989 page (i.e. holding down the shift key while clicking reload. Alternatively,
990 flush your browser's disk and memory caches).
992 If still a problem, go to http://config.privoxy.org/show-url-info and paste the
993 full URL of the page in question into the prompt. See which actions are being
994 applied to the URL, and which matches in which actions files are responsible
995 for that. Now, armed with this information, go to http://config.privoxy.org/
996 show-status and select the appropriate actions files for editing.
998 You can now either look for a section which disables the actions that you
999 suspect to cause the problem and add a pattern for your site there, or make up
1000 a completely new section for your site. In any case, the recommended way is to
1001 disable only the prime suspect, reload the problem page, and only if the
1002 problem persists, disable more and more actions until you have identified the
1003 culprit. You may or may not want to turn the other actions on again. Remember
1004 to flush your browser's caches in between any such changes!
1006 Alternately, if you are comfortable with a text editor, you can accomplish the
1007 same thing by editing the appropriate actions file. Probably the easiest way to
1008 deal with such problems when editing by hand is to add your site to a { fragile
1009 } section in user.action, which is an alias that turns off most "dangerous"
1010 actions, but is also likely to turn off more actions then needed, and thus
1011 lower your privacy and protection more than necessary,
1013 Troubleshooting actions is discussed in more detail in the user-manual appendix
1014 . There is also an actions tutorial.
1015 -------------------------------------------------------------------------------
1017 5.4. After installing Privoxy, I have to log in every time I start IE. What
1020 This is a quirk that effects the installation of Privoxy, in conjunction with
1021 Internet Explorer and Internet Connection Sharing on Windows 2000 and Windows
1022 XP. The symptoms may appear to be corrupted or invalid DUN settings, or
1025 When setting up an NT based Windows system with Privoxy you may find that
1026 things do not seem to be doing what you expect. When you set your system up you
1027 will probably have set up Internet Connection Sharing (ICS) with Dial up
1028 Networking (DUN) when logged in with administrator privileges. You will
1029 probably have made this DUN connection available to other accounts that you may
1030 have set-up on your system. E.g. Mum or Dad sets up the system and makes
1031 accounts suitably configured for the kids.
1033 When setting up Privoxy in this environment you will have to alter the proxy
1034 set-up of Internet Explorer (IE) for the specific DUN connection on which you
1035 wish to use Privoxy. When you do this the ICS DUN set-up becomes user specific.
1036 In this instance you will see no difference if you change the DUN connection
1037 under the account used to set-up the connection. However when you do this from
1038 another user you will notice that the DUN connection changes to make available
1039 to "Me only". You will also find that you have to store the password under each
1042 The reason for this is that each user's set-up for IE is user specific. Each
1043 set-up DUN connection and each LAN connection in IE store the settings for each
1044 user individually. As such this enforces individual configurations rather than
1045 common ones. Hence the first time you use a DUN connection after re-booting
1046 your system it may not perform as you expect, and prompt you for the password.
1047 Just set and save the password again and all should be OK.
1049 [Thanks to Ray Griffith for this submission.]
1050 -------------------------------------------------------------------------------
1052 5.5. I cannot connect to any FTP sites. Privoxy seems to be blocking me.
1054 Privoxy cannot act as a proxy for FTP traffic, so do not configure your browser
1055 to use Privoxy as an FTP proxy. The same is true for any protocol other than
1057 -------------------------------------------------------------------------------
1059 6. Contacting the developers, Bug Reporting and Feature Requests
1061 We value your feedback. In fact, we rely on it to improve Privoxy and its
1062 configuration. However, please note the following hints, so we can provide you
1063 with the best support:
1064 -------------------------------------------------------------------------------
1068 For casual users, our support forum at SourceForge is probably best suited:
1069 http://sourceforge.net/tracker/?group_id=11118&atid=211118
1071 All users are of course welcome to discuss their issues on the users mailing
1072 list, where the developers also hang around.
1073 -------------------------------------------------------------------------------
1077 Please report all bugs only through our bug tracker: http://sourceforge.net/
1078 tracker/?group_id=11118&atid=111118.
1080 Before doing so, please make sure that the bug has not already been submitted
1081 and observe the additional hints at the top of the submit form.
1083 Please try to verify that it is a Privoxy bug, and not a browser or site bug
1084 first. If unsure, try toggling off Privoxy, and see if the problem persists.
1085 The appendix of the user manual also has helpful information on action
1086 debugging. If you are using your own custom configuration, please try the stock
1087 configs to see if the problem is configuration related.
1089 If not using the latest version, chances are that the bug has been found and
1090 fixed in the meantime. We would appreciate if you could take the time to
1091 upgrade to the latest version (or even the latest CVS snapshot) and verify your
1092 bug, but this is not required for reporting.
1093 -------------------------------------------------------------------------------
1095 6.3. Request New Features
1097 You are welcome to submit ideas on new features or other proposals for
1098 improvement through our feature request tracker at http://sourceforge.net/
1099 tracker/?atid=361118&group_id=11118.
1100 -------------------------------------------------------------------------------
1102 6.4. Report Ads or Other Actions-Related Problems
1104 Please send feedback on ads that slipped through, innocent images that were
1105 blocked, and any other problems relating to the default.action file through our
1106 actions feedback mechanism located at http://www.privoxy.org/actions/. On this
1107 page, you will also find a bookmark which will take you back there from any
1108 troubled site and even pre-fill the form!
1110 New, improved default.action files will occasionally be made available based on
1111 your feedback. These will be announced on the ijbswa-announce list and
1112 available from our the files section of our project page.
1113 -------------------------------------------------------------------------------
1117 For any other issues, feel free to use the mailing lists. Technically
1118 interested users and people who wish to contribute to the project are also
1119 welcome on the developers list! You can find an overview of all Privoxy-related
1120 mailing lists, including list archives, at: http://sourceforge.net/mail/?
1122 -------------------------------------------------------------------------------
1124 7. Privoxy Copyright, License and History
1126 Copyright © 2001, 2002 by Privoxy Developers <developers@privoxy.org>
1128 Some source code is based on code Copyright © 1997 by Anonymous Coders and
1129 Junkbusters, Inc. and licensed under the GNU General Public License.
1131 Portions of this document are "borrowed" from the original Junkbuster (tm) FAQ,
1132 and modified as appropriate for Privoxy.
1133 -------------------------------------------------------------------------------
1137 Privoxy is free software; you can redistribute it and/or modify it under the
1138 terms of the GNU General Public License, version 2, as published by the Free
1139 Software Foundation.
1141 This program is distributed in the hope that it will be useful, but WITHOUT ANY
1142 WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A
1143 PARTICULAR PURPOSE. See the GNU General Public License for more details, which
1144 is available from the Free Software Foundation, Inc, 59 Temple Place - Suite
1145 330, Boston, MA 02111-1307, USA.
1147 You should have received a copy of the GNU General Public License along with
1148 this program; if not, write to the
1151 Foundation, Inc. 59 Temple Place - Suite 330
1152 Boston, MA 02111-1307
1154 -------------------------------------------------------------------------------
1158 In the beginning, there was the Internet Junkbuster, by Anonymous Coders and
1159 Junkbusters Corporation. It saved many users a lot of pain in the early days of
1160 web advertising and user tracking.
1162 But the web, its protocols and standards, and with it, the techniques for
1163 forcing users to consume ads, give up autonomy over their browsing, and for
1164 spying on them, kept evolving. Unfortunately, the Internet Junkbuster did not.
1165 Version 2.0.2, published in 1998, was (and is) the last official release
1166 available from Junkbusters Corporation. Fortunately, it had been released under
1167 the GNU GPL, which allowed further development by others.
1169 So Stefan Waldherr started maintaining an improved version of the software, to
1170 which eventually a number of people contributed patches. It could already
1171 replace banners with a transparent image, and had a first version of pop-up
1172 killing, but it was still very closely based on the original, with all its
1173 limitations, such as the lack of HTTP/1.1 support, flexible per-site
1174 configuration, or content modification. The last release from this effort was
1175 version 2.0.2-10, published in 2000.
1177 Then, some developers picked up the thread, and started turning the software
1178 inside out, upside down, and then reassembled it, adding many new features
1181 The result of this is Privoxy, whose first stable release, 3.0, is due in June