1 Privoxy Frequently Asked Questions
3 Copyright © 2001, 2002 by Privoxy Developers
5 $Id: faq.sgml,v 1.61.2.11 2002/08/06 08:54:03 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
51 2.7. In Mac OSX, I dragged the Privoxy folder to the trash in order to
52 uninstall it. Now the finder tells me I don't have sufficient
53 privileges to empty the trash.
57 3.1. Where can I get updated Actions Files?
58 3.2. Can I use my old config files?
59 3.3. What is an "actions" file?
60 3.4. The "actions" concept confuses me. Please list some of these "actions"
62 3.5. How are actions files configured? What is the easiest way to do this?
63 3.6. There are several different "actions" files. What are the differences?
64 3.7. How can I make my Yahoo/Hotmail/GMX account work?
65 3.8. What's the difference between the "Cautious", "Medium" and "Advanced"
67 3.9. Why can I change the configuration with a browser? Does that not raise
69 3.10. What is the default.filter file? What is a "filter"?
70 3.11. How can I set up Privoxy to act as a proxy for my LAN?
71 3.12. Instead of ads, now I get a checkerboard pattern. I don't want to see
73 3.13. Why would anybody want to see a checkerboard pattern?
74 3.14. I see some images being replaced by a text instead of the
75 checkerboard image. Why and how do I get rid of this?
76 3.15. Can Privoxy run as a service on Win2K/NT?
77 3.16. How can I make Privoxy work with other proxies like Squid?
78 3.17. Can Privoxy run as a "transparent" proxy?
82 4.1. How much does Privoxy slow my browsing down? This has to add extra
84 4.2. I noticed considerable delays in page requests compared to the old
85 Junkbuster. What's wrong?
86 4.3. What are "http://config.privoxy.org/" and "http://p.p/"?
87 4.4. Do you still maintain the blocklists?
88 4.5. How can I submit new ads?
89 4.6. How can I hide my IP address?
90 4.7. Can Privoxy guarantee I am anonymous?
91 4.8. Might some things break because header information or content is being
93 4.9. Can Privoxy act as a "caching" proxy to speed up web browsing?
94 4.10. What about as a firewall? Can Privoxy protect me?
95 4.11. I have large empty spaces / a checkerboard pattern now where ads used
97 4.12. How can Privoxy filter Secure (HTTPS) URLs?
98 4.13. Privoxy runs as a "server". How secure is it? Do I need to take any
100 4.14. How can I temporarily disable Privoxy?
101 4.15. When "disabled" is Privoxy totally out of the picture?
102 4.16. Where can I find more information about Privoxy and related issues?
106 5.1. I just upgraded and am getting "connection refused" with every web
108 5.2. I just added a new rule, but the steenkin ad is still getting through.
110 5.3. One of my favorite sites does not work with Privoxy. What can I do?
111 5.4. After installing Privoxy, I have to log in every time I start IE. What
113 5.5. I cannot connect to any FTP sites. Privoxy seems to be blocking me.
114 5.6. In Mac OSX, I can't configure Microsoft Internet Explorer to use
115 Privoxy as the HTTP proxy.
118 6. Contacting the developers, Bug Reporting and Feature Requests
121 6.3. Request New Features
122 6.4. Report Ads or Other Actions-Related Problems
126 7. Privoxy Copyright, License and History
132 1. General Information
134 1.1. What is this new version of Privoxy?
136 In the beginning, there was the Internet Junkbuster, by Anonymous Coders and
137 Junkbusters Corporation. It saved many users a lot of pain in the early days of
138 web advertising and user tracking.
140 But the web, its protocols and standards, and with it, the techniques for
141 forcing users to consume ads, give up autonomy over their browsing, and for
142 spying on them, kept evolving. Unfortunately, the Internet Junkbuster did not.
143 Version 2.0.2, published in 1998, was (and is) the last official release
144 available from Junkbusters Corporation. Fortunately, it had been released under
145 the GNU GPL, which allowed further development by others.
147 So Stefan Waldherr started maintaining an improved version of the software, to
148 which eventually a number of people contributed patches. It could already
149 replace banners with a transparent image, and had a first version of pop-up
150 killing, but it was still very closely based on the original, with all its
151 limitations, such as the lack of HTTP/1.1 support, flexible per-site
152 configuration, or content modification. The last release from this effort was
153 version 2.0.2-10, published in 2000.
155 Then, some developers picked up the thread, and started turning the software
156 inside out, upside down, and then reassembled it, adding many new features
159 The result of this is Privoxy, whose first stable release, 3.0, is due late
160 summer or early fall 2002.
161 -------------------------------------------------------------------------------
163 1.2. Why "Privoxy"? Why a name change at all?
165 Privoxy is the "Privacy Enhancing Proxy". Also, its content modification and
166 junk suppression allow you to browse your "private edition" of the web.
168 Junkbusters Corporation continues to offer their original version of the
169 Internet Junkbuster, so publishing our Junkbuster-derived software under the
170 same name led to confusion.
172 There are also potential legal complications from the continued use of the
173 Junkbuster name, which is a registered trademark of Junkbusters Corporation.
174 There are, however, no objections from Junkbusters Corporation to the Privoxy
175 project itself, and they, in fact, still share our ideals and goals.
177 The developers also believed that there are so many changes from the original
178 code, that it was time to make a clean break from the past and make a name in
179 their own right, especially now with the pending release of version 3.0.
180 -------------------------------------------------------------------------------
182 1.3. How does Privoxy differ from the old Junkbuster?
184 Privoxy picks up where Junkbuster left off. All the old features remain. The
185 new Privoxy still blocks ads and banners, still manages cookies, and still
186 helps protect your privacy. But, these are all enhanced, and many new features
187 have been added, all in the same vein.
189 The configuration has changed significantly as well. This is something that
190 users will notice right off the bat if upgrading from Junkbuster 2.0.x. The
191 "blocklist" "cookielist", "imagelist" and much more has been combined into the
192 "actions" files, with a completely different syntax. See the note to upgraders
195 Privoxy's new features include:
197 * Integrated browser based configuration and control utility at http://
198 config.privoxy.org/ (shortcut: http://p.p/). Browser-based tracing of rule
199 and filter effects. Remote toggling.
201 * Web page content filtering (removes banners based on size, invisible
202 "web-bugs", JavaScript and HTML annoyances, pop-up windows, etc.)
204 * Modularized configuration that allows for standard settings and user
205 settings to reside in separate files, so that installing updated actions
206 files won't overwrite individual user settings.
208 * HTTP/1.1 compliant (but not all optional 1.1 features are supported).
210 * Support for Perl Compatible Regular Expressions in the configuration files,
211 and generally a more sophisticated and flexible configuration syntax over
214 * Improved cookie management features (e.g. session based cookies).
218 * Bypass many click-tracking scripts (avoids script redirection).
220 * Multi-threaded (POSIX and native threads).
222 * User-customizable HTML templates for all proxy-generated pages (e.g.
225 * Auto-detection and re-reading of config file changes.
227 * Improved signal handling, and a true daemon mode (Unix).
229 * Every feature now controllable on a per-site or per-location basis,
230 configuration more powerful and versatile over-all.
232 * Many smaller new features added, limitations and bugs removed, and security
236 -------------------------------------------------------------------------------
237 1.4. What is a "proxy"? How does Privoxy work?
239 A web proxy is a service, based on a software such as Privoxy, that clients
240 (i.e. browsers) can use instead of connecting directly to the web servers on
241 the Internet. The clients then ask the proxy to fetch the objects they need
242 (web pages, images, movies etc) on their behalf, and when the proxy has done
243 so, it hands the results back to the client.
245 There are many reasons to use web proxies, such as security (firewalling),
246 efficiency (caching) and others, and there are just as many different proxies
247 to accommodate those needs.
249 Privoxy is a proxy that is solely focused on privacy protection and junk
250 elimination. Sitting between your browser(s) and the Internet, it is in a
251 perfect position to filter outbound personal information that your browser is
252 leaking, as well as inbound junk. It uses a variety of techniques to do this,
253 all of which are under your control via the various configuration files and
255 -------------------------------------------------------------------------------
257 1.5. How does Privoxy know what is an ad, and what is not?
259 Privoxy's approach to blocking ads is twofold:
261 First, there are certain patterns in the locations (URLs) of banner images.
262 This applies to both the path (you wouldn't guess how many web sites serve
263 their banners from a directory called "banners"!) and the host (blocking the
264 big banner hosting services like doublecklick.net already helps a lot). Privoxy
265 takes advantage of this fact by using URL patterns to sort out and block the
266 requests for banners.
268 Second, banners tend to come in certain sizes. But you can't tell the size of
269 an image by its URL without downloading it, and if you do, it's too late to
270 save bandwidth. Therefore, Privoxy also inspects the HTML sources of web pages
271 while they are loaded, and replaces references to images with standard banner
272 sizes by dummy references, so that your browser doesn't request them anymore in
275 Both of this involves a certain amount of guesswork and is, of course, freely
277 -------------------------------------------------------------------------------
279 1.6. Can Privoxy make mistakes? This does not sound very scientific.
281 Actually, it's a black art ;-) And yes, it is always possible to have a broad
282 rule accidentally block or change something by mistake. There is a good chance
283 you may run into such a situation at some point. It is tricky writing rules to
284 cover every conceivable possibility, and not occasionally get false positives.
286 But this should not be a big concern since the Privoxy configuration is very
287 flexible, and includes tools to help identify these types of situations so they
288 can be addressed as needed, allowing you to customize your installation. (See
289 the Troubleshooting section below.)
290 -------------------------------------------------------------------------------
292 1.7. My browser does the same things as Privoxy. Why should I use Privoxy at
295 Modern browsers do indeed have some of the same functionality as Privoxy. Maybe
296 this is adequate for you. But Privoxy is much more versatile and powerful, and
297 can do a number of things that browsers just can't.
299 In addition, a proxy is good choice if you use multiple browsers, or have a LAN
300 with multiple computers. This way all the configuration is in one place, and
301 you don't have to maintain a similar configuration for possibly many browsers.
302 -------------------------------------------------------------------------------
304 1.8. Is there is a license or fee? What about a warranty? Registration?
306 Privoxy is licensed under the GNU General Public License (GPL). It is free to
307 use, copy, modify or distribute as you wish under the terms of this license.
308 Please see the Copyright section for more information on the license and
309 copyright. Or the LICENSE file that should be included.
311 There is no warranty of any kind, expressed, implied or otherwise. That is
312 something that would cost real money ;-) There is no registration either.
313 Privoxy really is free in every respect!
314 -------------------------------------------------------------------------------
316 1.9. I would like to help you, what do I do?
318 1.9.1. Money Money Money
320 We, of course, welcome donations and could use money for domain registering,
321 buying software to test Privoxy with, and, of course, for regular world-wide
322 get-togethers (hahaha). If you enjoy the software and feel like helping us with
323 a donation, just drop us a note.
324 -------------------------------------------------------------------------------
328 If you are a vendor of a web-related software like a browser, web server or
329 proxy, and would like us to ensure that Privoxy runs smoothly with your
330 product, you might consider supplying us with a copy or license. We can't,
331 however, guarantee that we will fix all potential compatibility issues as a
333 -------------------------------------------------------------------------------
335 1.9.3. You want to work with us?
337 Well, helping the team is always a good idea. We welcome new developers,
338 packaging gurus or documentation writers. Simply get an account on
339 SourceForge.net and mail your id to the developers mailing list. Then read the
342 Once we have added you to the team, you'll have write access to the CVS
343 repository, and together we'll find a suitable task for you.
344 -------------------------------------------------------------------------------
348 2.1. Which browsers are supported by Privoxy?
350 Any browser that can be configured to use a proxy, which should be virtually
351 all browsers. Direct browser support is not necessary since Privoxy runs as a
352 separate application and talks to the browser in the standardized HTTP
353 protocol, just like a web server does.
354 -------------------------------------------------------------------------------
356 2.2. Which operating systems are supported?
358 At present, Privoxy is known to run on Windows(95, 98, ME, 2000, XP), Linux
359 (RedHat, SuSE, Debian, Conectiva, Gentoo), Mac OSX, OS/2, AmigaOS, BeOS,
360 FreeBSD, NetBSD, Solaris, and many more flavors of Unix.
362 But any operating system that runs TCP/IP, can conceivably take advantage of
363 Privoxy in a networked situation where Privoxy would run as a server on a LAN
364 gateway. Then only the "gateway" needs to be running one of the above operating
367 Source code is freely available, so porting to other operating systems is
368 always a possibility.
369 -------------------------------------------------------------------------------
371 2.3. Can I install Privoxy over Junkbuster?
373 We recommend you un-install Junkbuster first to minimize conflicts and
374 confusion. You may want to save your old configuration files for future
375 reference. The configuration files and syntax have substantially changed, so
376 you will need to manually port your old patterns. See the note to upgraders and
377 installation chapter in the user manual for details.
379 Note: Some installers may automatically un-install Junkbuster, if present!
380 -------------------------------------------------------------------------------
382 2.4. I just installed Privoxy. Is there anything special I have to do now?
384 All browsers must be told to use Privoxy as a proxy by specifying the correct
385 proxy address and port number in the appropriate configuration area for the
386 browser. See below. You should also flush your browser's memory and disk cache
387 to get rid of any cached junk items.
388 -------------------------------------------------------------------------------
390 2.5. What is the proxy address of Privoxy?
392 If you set up the Privoxy to run on the computer you browse from (rather than
393 your ISP's server or some networked computer on a LAN), the proxy will be on
394 127.0.0.1 (sometimes referred to as "localhost", which is the special name used
395 by every computer on the Internet to refer to itself) and the port will be 8118
396 (unless you have Privoxy to run on a different port with the listen-address
399 When configuring your browser's proxy settings you typically enter the word
400 "localhost" or the IP address "127.0.0.1" in the boxes next to "HTTP" and
401 "Secure" (HTTPS) and then the number "8118" for "port". This tells your browser
402 to send all web requests to Privoxy instead of directly to the Internet.
404 Privoxy can also be used to proxy for a Local Area Network. In this case, your
405 would enter either the IP address of the LAN host where Privoxy is running, or
406 the equivalent hostname. Port assignment would be same as above. Note that
407 Privoxy doesn't listen on any LAN interfaces by default.
409 Privoxy does not currently handle protocols such as FTP, SMTP, IM, IRC, ICQ, or
410 other Internet protocols.
411 -------------------------------------------------------------------------------
413 2.6. I just installed Privoxy, and nothing is happening. All the ads are there.
416 Did you configure your browser to use Privoxy as a proxy? It does not sound
417 like it. See above. You might also try flushing the browser's caches to force a
418 full re-reading of pages. You can verify that Privoxy is running, and your
419 browser is correctly configured by entering the special URL: http://
420 config.privoxy.org/. This should take you to a page titled "This is Privoxy.."
421 with access to Privoxy's internal configuration. If you see this, then you are
422 good to go. If you receive a page saying "Privoxy is not running", then the
423 browser is not set up to use your Privoxy installation. If you receive anything
424 else (probably nothing at all), it could either be that the browser is not set
425 up correctly, or that Privoxy is not running at all. Check the log file.
426 -------------------------------------------------------------------------------
428 2.7. In Mac OSX, I dragged the Privoxy folder to the trash in order to
429 uninstall it. Now the finder tells me I don't have sufficient privileges to
432 Privoxy is installed with root permissions. When you drag the Privoxy folder to
433 the trash, the general user does not have (as the Finder says) sufficient
434 privileges to delete it. Unfortunately, the finder does not offer a way to
435 enter the administrator password in order to prove you do in fact own this
436 computer. To fix this situation, open the Terminal application and carefully
437 enter the following commands:
443 The trash may still appear full after this command; emptying the trash from the
444 desktop should make it appear empty again.
446 +-----------------------------------------------------------------------------+
448 +-----------------------------------------------------------------------------+
449 |Be extra-sure to enter the commands EXACTLY as shown above. Removing files |
450 |recusively with administrator priviledges (as happens with sudo rm -rf is |
451 |serious business and even small typos can have devasting effects! |
452 +-----------------------------------------------------------------------------+
453 -------------------------------------------------------------------------------
457 3.1. Where can I get updated Actions Files?
459 Based on your feedback and the continuing development, updated actions files
460 will be made available on the files section of our project page.
462 If you wish to receive an email notification whenever we release updates of
463 Privoxy or the actions file, subscribe to our announce mailing list,
464 ijbswa-announce@lists.sourceforge.net.
465 -------------------------------------------------------------------------------
467 3.2. Can I use my old config files?
469 The syntax, number, and purpose of configuration files has substantially
470 changed from Junkbuster and earlier versions of Privoxy. The old files, like
471 blocklist will not work at all. If you are upgrading from a 2.0.x version, you
472 will need to port your configuration data to the new format. Note that even the
473 pattern syntax has changed! Even configuration files from the 2.9.x versions
474 will need to be adapted, as configuration syntax has been very much in flow in
476 -------------------------------------------------------------------------------
478 3.3. What is an "actions" file?
480 Actions files are where various actions that Privoxy might take while
481 processing a certain request, are configured. Typically, you would define a set
482 of default actions that apply to all URLs, then add exceptions to these
483 defaults where needed.
485 Actions can be defined on a URL pattern basis, i.e. for single URLs, whole web
486 sites, groups or parts thereof etc. Actions can also be grouped together and
487 then applied to requests matching one or more patterns. There are many possible
488 actions that might apply to any given site. As an example, if you are blocking
489 cookies as one of your default actions, but need to accept cookies from a given
490 site, you would need to define an exception for this site in one of your
491 actions files, preferably in user.action
492 -------------------------------------------------------------------------------
494 3.4. The "actions" concept confuses me. Please list some of these "actions".
496 For a comprehensive discussion of the actions concept, please refer to the
497 actions file chapter in the user manual. It includes a list of all actions and
498 an actions file tutorial to get you started.
499 -------------------------------------------------------------------------------
501 3.5. How are actions files configured? What is the easiest way to do this?
503 Actions files are just text files in a special syntax and can be edited with a
504 text editor. The probably easiest way is to access Privoxy's user interface
505 with your web browser at http://config.privoxy.org/ (Shortcut: http://p.p/) and
506 then select "View & change the current configuration" from the menu.
507 -------------------------------------------------------------------------------
509 3.6. There are several different "actions" files. What are the differences?
511 As of Privoxy v2.9.15, three actions files are being included, to be used for
512 different purposes: These are default.action, the "main" actions file which is
513 actively maintained by the Privoxy developers, user.action, where users are
514 encouraged to make their private customizations, and standard.action, which is
515 for internal Privoxy use only. Please see the actions chapter in the user
516 manual for a more detailed explanation.
518 Earlier versions included three different versions of the default.action file.
519 The new scheme allows for greater flexibility of local configuration, and for
520 browser based selection of pre-defined "aggressiveness" levels.
521 -------------------------------------------------------------------------------
523 3.7. How can I make my Yahoo/Hotmail/GMX account work?
525 The default configuration shouldn't impact the usability of any of these
526 services. It will, however, make all cookies temporary, so that your browser
527 will forget your login credentials in between browser sessions. If you would
528 like not to have to log in manually each time you access those websites, simply
529 turn off all cookie handling for them in the user.action file. An example for
530 yahoo might look like:
532 # Allow all cookies for Yahoo login:
534 { -crunch-incoming-cookies -crunch-outgoing-cookies -session-cookies-only }
536 -------------------------------------------------------------------------------
538 3.8. What's the difference between the "Cautious", "Medium" and "Advanced"
541 Configuring Privoxy is not entirely trivial. To help you get started, we
542 provide you with three different default action "packages" in the web based
543 actions file editor at http://config.privoxy.org/show-status. The following
544 table shows you, which of the most important features are enabled in each
547 Table 1. Default Configurations
548 +-------------------+------------------+-------------------+------------------+
549 |Feature |Cautious |Intermadiate |Advanced |
550 +-------------------+------------------+-------------------+------------------+
551 |Ad-blocking by URL |yes |yes |yes |
552 +-------------------+------------------+-------------------+------------------+
553 |Ad-filtering by |yes |yes |yes |
555 +-------------------+------------------+-------------------+------------------+
556 |GIF de-animation |no |yes |yes |
557 +-------------------+------------------+-------------------+------------------+
558 |Referer forging |no |yes |yes |
559 +-------------------+------------------+-------------------+------------------+
560 |Cookie handling |none |session-only |kill |
561 +-------------------+------------------+-------------------+------------------+
562 |Pop-up killing |no |yes |yes |
563 +-------------------+------------------+-------------------+------------------+
564 |Fast redirects |no |no |yes |
565 +-------------------+------------------+-------------------+------------------+
566 |HTML taming |yes |yes |yes |
567 +-------------------+------------------+-------------------+------------------+
568 |JavaScript taming |yes |yes |yes |
569 +-------------------+------------------+-------------------+------------------+
570 |Web-bug killing |yes |yes |yes |
571 +-------------------+------------------+-------------------+------------------+
572 |Fun text |no |no |yes |
573 |replacements | | | |
574 +-------------------+------------------+-------------------+------------------+
575 |Image tag |no |no |yes |
577 +-------------------+------------------+-------------------+------------------+
578 |Ad-filtering by |no |no |yes |
580 +-------------------+------------------+-------------------+------------------+
582 Where the defaults are likely to break some sites, exceptions for known popular
583 "problem" sites are included, but in general, the more aggressive your default
584 settings are, the more exceptions you will have to make later. See the user
585 manual for a more deatiled discussion.
586 -------------------------------------------------------------------------------
588 3.9. Why can I change the configuration with a browser? Does that not raise
591 It may seem strange that regular users can edit the config files with their
592 browsers, although the whole /etc/privoxy hierarchy belongs to the user
593 "privoxy", with only 644 permissions.
595 When you use the browser-based editor, Privoxy itself is writing to the config
596 files. Because Privoxy is running as the user "privoxy", it can update the
599 If you run Privoxy for multiple untrusted users (e.g. in a LAN), you will
600 probably want to turn the web-based editor and remote toggle features off by
601 setting "enable-edit-actions 0" and "enable-remote-toggle 0" in the main
604 Note that in the default configuration, only local users (i.e. those on
605 "localhost") can connect to Privoxy, so this is not (normally) a security
607 -------------------------------------------------------------------------------
609 3.10. What is the default.filter file? What is a "filter"?
611 The default.filter file is where filters are defined, which can be used to
612 modify or remove, web page content on the fly. Filters apply to anything in the
613 page source, including HTML tags, and JavaScript. Regular expressions are used
614 to accomplish this. There are a number of pre-defined filters to deal with
615 common annoyances. The filters are only defined here, to invoke them, you need
616 to use the filter action in one of the actions files. Filtering is
617 automatically disabled for inappropriate MIME types.
619 If you are familiar with regular expressions, and HTML, you can look at the
620 provided default.filter with a text editor and define your own filters. This is
621 potentially a very powerful feature, but requires some expertise in both
622 regular expressions and HTML/HTTP.
624 Presently, there is no GUI editor option for this part of the configuration,
625 but you can disable/enable the various pre-defined filters of the included
626 default.filter file with the web-based actions file editor.
627 -------------------------------------------------------------------------------
629 3.11. How can I set up Privoxy to act as a proxy for my LAN?
631 By default, Privoxy only responds to requests from 127.0.0.1 (localhost). To
632 have it act as a server for a network, this needs to be changed in the main
633 configuration file. Look for the listen-address option, which may be commented
634 out with a "#" symbol. Make sure it is uncommented, and assign it the address
635 of the LAN gateway interface, and port number to use. Assuming your LAN address
636 is 192.168.1.1 and you wish to run Privoxy on port 8118, this line should look
639 listen-address 192.168.1.1:8118
641 Save the file, and restart Privoxy. Configure all browsers on the network then
642 to use this address and port number.
644 If you run Privoxy on a LAN with untrusted users, we recommend that you
645 double-check the access control and security options!
646 -------------------------------------------------------------------------------
648 3.12. Instead of ads, now I get a checkerboard pattern. I don't want to see
651 The replacement for blocked images can be controlled with the set-image-blocker
652 action. You have the choice of a checkerboard pattern, a transparent 1x1 GIF
653 image (aka "blank"), or a redirect to a custom image of your choice. Note that
654 this choice only has effect for images which are blocked as images, i.e. whose
655 URLs match both a handle-as-image and block action.
657 If you want to see nothing, then change the set-image-blocker action to "blank"
658 . This can be done by editing the default.action file, or trough the web-based
660 -------------------------------------------------------------------------------
662 3.13. Why would anybody want to see a checkerboard pattern?
664 Remember that telling which image is an ad and which isn't, is mostly
665 guesswork. While we hope that the standard configuration is rather smart, it
666 can and will make errors. The checkerboard image is visually decent, but it
667 shows you that and where images were blocked, which can be very helpful in case
668 some navigation aid or otherwise innocent image was erraneously blocked. Some
669 people might also enjoy seeing how many banners they don't have to see..
670 -------------------------------------------------------------------------------
672 3.14. I see some images being replaced by a text instead of the checkerboard
673 image. Why and how do I get rid of this?
675 This happens when the banners are not embedded in the HTML code of the page
676 itself, but in separate HTML (sub)documents that are loaded into (i)frames or
677 (i)layers, and these external HTML documents are blocked. Being non-images they
678 get replaced by a substitute HTML page rather than a substitute image, which
679 wouldn't work out technically, since the browser expects and accepts only HTML
680 when it has requested an HTML document.
682 The substitute page adapts to the available space and shows itself as a
683 miniature two-liner if loaded into small frames, or full-blown with a large red
684 "BLOCKED" banner if space allows.
686 If you prefer the banners to be blocked by images, you must see to it that the
687 HTML documents in which they are embedded are not blocked. Clicking the "See
688 why" link offered in the substitute page will show you which rule blocked the
689 page. After changing the rule and un-blocking the HTML documents, the browser
690 will try to load the actual banner images and the usual image blocking will
691 (hopefully!) kick in.
692 -------------------------------------------------------------------------------
694 3.15. Can Privoxy run as a service on Win2K/NT?
696 Yes, it can run as a system service using srvany.exe. The only catch is that
697 this will effectively disable the Privoxy icon (and its menu!) in the taskbar.
698 You can have one or the other, but not both at this time :(
700 There is a pending feature request for this functionality. See the discussion
701 at http://sourceforge.net/tracker/?func=detail&atid=361118&aid=485617&group_id=
702 11118, for details, and a sample configuration.
703 -------------------------------------------------------------------------------
705 3.16. How can I make Privoxy work with other proxies like Squid?
707 This can be done and is often useful to combine the benefits of Privoxy with
708 those of a caching proxy. See the forwarding chapter in the user manual which
709 describes how to do this.
710 -------------------------------------------------------------------------------
712 3.17. Can Privoxy run as a "transparent" proxy?
714 No, Privoxy currently does not have this ability, though it is planned for a
715 future release. Transparent proxies require special handling of the request
716 headers beyond what Privoxy is now capable of.
718 Chaining Privoxy behind another proxy that has this ability should work though.
719 See the forwarding chapter in the user manual. As a transparent proxy to be
720 used for chaining we recommend Transproxy (http://www.transproxy.nlc.net.au/).
721 -------------------------------------------------------------------------------
725 4.1. How much does Privoxy slow my browsing down? This has to add extra time to
728 It should not slow you down any in real terms, and may actually help speed
729 things up since ads, banners and other junk are not being displayed. The actual
730 processing time required by Privoxy itself for each page, is relatively small
731 in the overall scheme of things, and happens very quickly. This is typically
732 more than offset by time saved not downloading and rendering ad images.
734 "Filtering" content via the filter or deanimate-gifs actions may cause a
735 perceived slowdown, since the entire document needs to be buffered before
736 displaying. See below.
737 -------------------------------------------------------------------------------
739 4.2. I noticed considerable delays in page requests compared to the old
740 Junkbuster. What's wrong?
742 If you use any filter action, such as filtering banners by size, web-bugs etc,
743 or the deanimate-gifs action, the entire document must be loaded into memory in
744 order for the filtering mechanism to work, and nothing is sent to the browser
747 The loading time does not really change in real numbers, but the feeling is
748 different, because most browsers are able to start rendering incomplete
749 content, giving the user a feeling of "it works". This effect is especially
750 noticeable on slow dialup connections.
752 Filtering is automatically disabled for inappropriate MIME types.
753 -------------------------------------------------------------------------------
755 4.3. What are "http://config.privoxy.org/" and "http://p.p/"?
757 http://config.privoxy.org/ is the address of Privoxy's built-in user interface,
758 and http://p.p/ is a shortcut for it.
760 Since Privoxy sits between your web browser and the Internet, it can simply
761 intercept requests for these addresses and answer them with its built-in "web
764 This also makes for a good test for your browser configuration: If entering the
765 URL http://config.privoxy.org/ takes you to a page saying "This is Privoxy..",
766 everything is OK. If you get a page saying "Privoxy is not working" instead,
767 then your browser didn't use Privoxy for the request, hence it could not be
768 intercepted, and you have accessed the real web site at config.privoxy.org.
770 With recent versions of Privoxy (version 2.9.x and later), the user interface
771 features information on the run time status, the configuration, and even a
772 built-in editor for the actions files.
774 Note that the built-in URLs from earlier versions of Junkbuster / Privoxy,
775 http://example.com/show-proxy-args and http://i.j.b/, are no longer supported.
776 If you still use such an old version, you should really consider upgrading to
778 -------------------------------------------------------------------------------
780 4.4. Do you still maintain the blocklists?
782 No. The patterns for blocking now reside (among other things) in the actions
783 files, which are actively maintained instead. See next question ...
784 -------------------------------------------------------------------------------
786 4.5. How can I submit new ads?
788 Yes, absolutely! Please see the Contact section for how to do that. Please note
789 that you (technically) need the latest Privoxy version for this to work.
790 -------------------------------------------------------------------------------
792 4.6. How can I hide my IP address?
794 If you run both the browser and the proxy locally, you cannot hide your IP
795 address with Privoxy or any other software. The server needs to know your IP
796 address to send the answers back to you.
798 Fortunately there are many publicly usable anonymous proxies out there, which
799 solve the problem by providing a further level of indirection between you and
800 the web server, shared by many people, and thus letting your requests "drown"
801 in white noise of unrelated requests as far as user tracking is concerned.
803 Most of them will, however, log your IP address and make it available to the
804 authorities in case you abuse that anonymity for criminal purposes. In fact you
805 can't even rule out that some of them only exist to *collect* information on
806 (those suspicious) people with a more than average preference for privacy.
808 You can find a list of anonymous public proxies at multiproxy.org and many more
809 through Google. A particularly interesting project is the JAP service offered
810 by the Technical University of Dresden (http://anon.inf.tu-dresden.de/
813 There is, however, even in the single-machine case the possibility to make the
814 server believe that your machine is in fact a shared proxy serving a whole big
815 LAN, and we are looking into that.
816 -------------------------------------------------------------------------------
818 4.7. Can Privoxy guarantee I am anonymous?
820 No. Your chances of remaining anonymous are greatly improved, but unless you
821 are an expert on Internet security it would be safest to assume that everything
822 you do on the Web can be traced back to you.
824 Privoxy can remove various information about you, and allows you more freedom
825 to decide which sites you can trust, and what details you want to reveal. But
826 it's still possible that web sites can find out who you are. Here's one way
829 A few browsers disclose the user's email address in certain situations, such as
830 when transferring a file by FTP. Privoxy does not filter FTP. If you need this
831 feature, or are concerned about the mail handler of your browser disclosing
832 your email address, you might consider products such as NSClean.
834 Browsers available only as binaries could use non-standard headers to give out
835 any information they can have access to: see the manufacturer's license
836 agreement. It's impossible to anticipate and prevent every breach of privacy
837 that might occur. The professionally paranoid prefer browsers available as
838 source code, because anticipating their behavior is easier. Trust the source,
840 -------------------------------------------------------------------------------
842 4.8. Might some things break because header information or content is being
845 Definitely. More and more sites use HTTP header content to decide what to
846 display and how to display it. There is many ways that this can be handled, so
847 having hard and fast rules, is tricky.
849 "User-Agent" in particular is often used in this way to identify the browser,
850 and adjust content accordingly. Changing this now (at least not further than
851 removing the OS information) is not recommended, since so many sites do look
852 for it. You may get undesirable results by changing this.
854 For instance, different browsers use different encodings of Russian and Czech
855 characters, certain web servers convert pages on-the-fly according to the User
856 Agent header. Giving a "User Agent" with the wrong operating system or browser
857 manufacturer causes some sites in these languages to be garbled; Surfers to
858 Eastern European sites should change it to something closer. And then some page
859 access counters work by looking at the "Referer" header; they may fail or break
860 if unavailable. The weather maps of Intellicast have been blocked by their
861 server when no "Referer" or cookie is provided, is another example. (But you
862 can forge both headers without giving information away). There are many other
863 ways things can go wrong when trying to fool a web server.
865 Similar thoughts apply to modifying JavaScript, and, to a lesser degree, HTML
868 If you have problems with a site, you will have to adjust your configuration
869 accordingly. Cookies are probably the most likely adjustment that may be
870 required, but by no means the only one.
871 -------------------------------------------------------------------------------
873 4.9. Can Privoxy act as a "caching" proxy to speed up web browsing?
875 No, it does not have this ability at all. You want something like Squid for
876 this. And, yes, before you ask, Privoxy can co-exist with other kinds of
877 proxies like Squid. See the forwarding chapter in the user manual for details.
878 -------------------------------------------------------------------------------
880 4.10. What about as a firewall? Can Privoxy protect me?
882 Not in the way you mean, or in the way a true firewall can. Privoxy can help
883 protect your privacy, but not protect you from intrusion attempts. It is, of
884 course, perfectly possible and recommended to use both.
885 -------------------------------------------------------------------------------
887 4.11. I have large empty spaces / a checkerboard pattern now where ads used to
890 It would be technically possible eliminate the banners in a way that frees
891 their screen estate in many cases, by doing all banner blocking with filters,
892 i.e. eliminating the whole image references from the HTML pages instead of
893 letting them stay in, and blocking the resulting requests for the banners
896 But this would consume considerable CPU resources, would likely destroy the
897 layout of many web pages which rely on the banners consuming a certain amount
898 of screen space, and would fail in other cases, where the screen space is
899 reserved e.g. by tables anyway. Also, making the banners disappear without a
900 visual trace complicates troubleshooting.
902 So we won't support this in the default configuration, but you can of course
903 define appropriate filters yourself.
904 -------------------------------------------------------------------------------
906 4.12. How can Privoxy filter Secure (HTTPS) URLs?
908 Since secure HTTP connections are encrypted SSL sessions between your browser
909 and the secure site, and are meant to be reliably secure, there is little that
910 Privoxy can do but hand the raw gibberish data though from one end to the other
913 The only exception to this is blocking by host patterns, as the client needs to
914 tell Privoxy the name of the remote server, so that Privoxy can establish the
915 connection. If that name matches a host-only pattern, the connection will be
918 As far as ad blocking is concerned, this is less of a restriction than it may
919 seem, since ad sources are often identifiable by the host name, and often the
920 banners to be placed in an encrypted page come unencrypted nonetheless for
921 efficiency reasons, which exposes them to the full power of Privoxy's ad
923 -------------------------------------------------------------------------------
925 4.13. Privoxy runs as a "server". How secure is it? Do I need to take any
928 There are no known exploits that might affect Privoxy. On Unix-like systems,
929 Privoxy can run as a non-privileged user, which is how we recommend it be run.
930 Also, by default Privoxy only listens to requests from "localhost" only. The
931 server aspect of Privoxy is not itself directly exposed to the Internet in this
932 configuration. If you want to have Privoxy serve as a LAN proxy, this will have
933 to be opened up to allow for LAN requests. In this case, we'd recommend you
934 specify only the LAN gateway address, e.g. 192.168.1.1, in the main Privoxy
935 configuration file and check all access control and security options. All LAN
936 hosts can then use this as their proxy address in the browser proxy
937 configuration, but Privoxy will not listen on any external interfaces. ACLs can
938 be defined in addition, and using a firewall is always good too. Better safe
940 -------------------------------------------------------------------------------
942 4.14. How can I temporarily disable Privoxy?
944 The easiest way is to access Privoxy with your browser by using the remote
945 toggle URL: http://config.privoxy.org/toggle. See the Bookmarklets section of
946 the User Manual for an easy way to access this feature.
947 -------------------------------------------------------------------------------
949 4.15. When "disabled" is Privoxy totally out of the picture?
951 No, this just means all filtering and actions are disabled. Privoxy is still
952 acting as a proxy, but just not doing any of the things that Privoxy would
953 normally be expected to do. It is still a "middle-man" in the interaction
954 between your browser and web sites.
955 -------------------------------------------------------------------------------
957 4.16. Where can I find more information about Privoxy and related issues?
959 Other references and sites of interest to Privoxy users:
961 http://www.privoxy.org/, the Privoxy Home page.
963 http://www.privoxy.org/faq/, the Privoxy FAQ.
965 http://sourceforge.net/projects/ijbswa/, the Project Page for Privoxy on
968 http://config.privoxy.org/, the web-based user interface. Privoxy must be
969 running for this to work. Shortcut: http://p.p/
971 http://www.privoxy.org/actions/, to submit "misses" to the developers.
973 http://www.junkbusters.com/ht/en/cookies.html, an explanation how cookies are
974 used to track web users.
976 http://www.junkbusters.com/ijb.html, the original Internet Junkbuster.
978 http://www.waldherr.org/junkbuster/, Stefan Waldherr's version of Junkbuster,
979 from which Privoxy was derived.
981 http://privacy.net/analyze/, a useful site to check what information about you
982 is leaked while you browse the web.
984 http://www.squid-cache.org/, a very popular caching proxy, which is often used
985 together with Privoxy.
987 http://www.privoxy.org/developer-manual/, the Privoxy developer manual.
989 -------------------------------------------------------------------------------
992 5.1. I just upgraded and am getting "connection refused" with every web page?
994 Either Privoxy is not running, or your browser is configured for a different
995 port than what Privoxy is using.
997 The old Privoxy (and also Junkbuster) used port 8000 by default. This has been
998 changed to port 8118 now, due to a conflict with NAS (Network Audio Service),
999 which uses port 8000. If you haven't, you need to change your browser to the
1000 new port number, or alternately change the listen-address option in Privoxy's
1001 main configuration file.
1002 -------------------------------------------------------------------------------
1004 5.2. I just added a new rule, but the steenkin ad is still getting through.
1007 If the ad had been displayed before you added its URL, it will probably be held
1008 in the browser's cache for some time, so it will be displayed without the need
1009 for any request to the server, and Privoxy will not be in the picture. The best
1010 thing to do is try flushing the browser's caches. And then try again.
1012 If this doesn't help, you probably have an error in the rule you applied. Try
1013 pasting the full URL of the offending ad into http://config.privoxy.org/
1014 show-url-info and see if it really matches your new rule.
1015 -------------------------------------------------------------------------------
1017 5.3. One of my favorite sites does not work with Privoxy. What can I do?
1019 First verify that it is indeed a Privoxy problem, by toggling off Privoxy
1020 through http://config.privoxy.org/toggle, and then shift-reloading the problem
1021 page (i.e. holding down the shift key while clicking reload. Alternatively,
1022 flush your browser's disk and memory caches).
1024 If still a problem, go to http://config.privoxy.org/show-url-info and paste the
1025 full URL of the page in question into the prompt. See which actions are being
1026 applied to the URL, and which matches in which actions files are responsible
1027 for that. Now, armed with this information, go to http://config.privoxy.org/
1028 show-status and select the appropriate actions files for editing.
1030 You can now either look for a section which disables the actions that you
1031 suspect to cause the problem and add a pattern for your site there, or make up
1032 a completely new section for your site. In any case, the recommended way is to
1033 disable only the prime suspect, reload the problem page, and only if the
1034 problem persists, disable more and more actions until you have identified the
1035 culprit. You may or may not want to turn the other actions on again. Remember
1036 to flush your browser's caches in between any such changes!
1038 Alternately, if you are comfortable with a text editor, you can accomplish the
1039 same thing by editing the appropriate actions file. Probably the easiest way to
1040 deal with such problems when editing by hand is to add your site to a { fragile
1041 } section in user.action, which is an alias that turns off most "dangerous"
1042 actions, but is also likely to turn off more actions then needed, and thus
1043 lower your privacy and protection more than necessary,
1045 Troubleshooting actions is discussed in more detail in the user-manual appendix
1046 . There is also an actions tutorial.
1047 -------------------------------------------------------------------------------
1049 5.4. After installing Privoxy, I have to log in every time I start IE. What
1052 This is a quirk that effects the installation of Privoxy, in conjunction with
1053 Internet Explorer and Internet Connection Sharing on Windows 2000 and Windows
1054 XP. The symptoms may appear to be corrupted or invalid DUN settings, or
1057 When setting up an NT based Windows system with Privoxy you may find that
1058 things do not seem to be doing what you expect. When you set your system up you
1059 will probably have set up Internet Connection Sharing (ICS) with Dial up
1060 Networking (DUN) when logged in with administrator privileges. You will
1061 probably have made this DUN connection available to other accounts that you may
1062 have set-up on your system. E.g. Mum or Dad sets up the system and makes
1063 accounts suitably configured for the kids.
1065 When setting up Privoxy in this environment you will have to alter the proxy
1066 set-up of Internet Explorer (IE) for the specific DUN connection on which you
1067 wish to use Privoxy. When you do this the ICS DUN set-up becomes user specific.
1068 In this instance you will see no difference if you change the DUN connection
1069 under the account used to set-up the connection. However when you do this from
1070 another user you will notice that the DUN connection changes to make available
1071 to "Me only". You will also find that you have to store the password under each
1074 The reason for this is that each user's set-up for IE is user specific. Each
1075 set-up DUN connection and each LAN connection in IE store the settings for each
1076 user individually. As such this enforces individual configurations rather than
1077 common ones. Hence the first time you use a DUN connection after re-booting
1078 your system it may not perform as you expect, and prompt you for the password.
1079 Just set and save the password again and all should be OK.
1081 [Thanks to Ray Griffith for this submission.]
1082 -------------------------------------------------------------------------------
1084 5.5. I cannot connect to any FTP sites. Privoxy seems to be blocking me.
1086 Privoxy cannot act as a proxy for FTP traffic, so do not configure your browser
1087 to use Privoxy as an FTP proxy. The same is true for any protocol other than
1089 -------------------------------------------------------------------------------
1091 5.6. In Mac OSX, I can't configure Microsoft Internet Explorer to use Privoxy
1094 Microsoft Internet Explorer (in versions like 5.1) respects system-wide network
1095 settings. In order to change the HTTP proxy, open System Preferences, and click
1096 on the Network icon. In the settings pane that comes up, click on the Proxies
1097 tab. Ensure the "Web Proxy (HTTP)" checkbox is checked and enter 127.0.0.1 in
1098 the entry field. Enter 8118 in the Port field. The next time you start IE, it
1099 should reflect these values.
1100 -------------------------------------------------------------------------------
1102 6. Contacting the developers, Bug Reporting and Feature Requests
1104 We value your feedback. In fact, we rely on it to improve Privoxy and its
1105 configuration. However, please note the following hints, so we can provide you
1106 with the best support:
1107 -------------------------------------------------------------------------------
1111 For casual users, our support forum at SourceForge is probably best suited:
1112 http://sourceforge.net/tracker/?group_id=11118&atid=211118
1114 All users are of course welcome to discuss their issues on the users mailing
1115 list, where the developers also hang around.
1116 -------------------------------------------------------------------------------
1120 Please report all bugs only through our bug tracker: http://sourceforge.net/
1121 tracker/?group_id=11118&atid=111118.
1123 Before doing so, please make sure that the bug has not already been submitted
1124 and observe the additional hints at the top of the submit form.
1126 Please try to verify that it is a Privoxy bug, and not a browser or site bug
1127 first. If unsure, try toggling off Privoxy, and see if the problem persists.
1128 The appendix of the user manual also has helpful information on action
1129 debugging. If you are using your own custom configuration, please try the stock
1130 configs to see if the problem is configuration related.
1132 If not using the latest version, chances are that the bug has been found and
1133 fixed in the meantime. We would appreciate if you could take the time to
1134 upgrade to the latest version (or even the latest CVS snapshot) and verify your
1135 bug, but this is not required for reporting.
1136 -------------------------------------------------------------------------------
1138 6.3. Request New Features
1140 You are welcome to submit ideas on new features or other proposals for
1141 improvement through our feature request tracker at http://sourceforge.net/
1142 tracker/?atid=361118&group_id=11118.
1143 -------------------------------------------------------------------------------
1145 6.4. Report Ads or Other Actions-Related Problems
1147 Please send feedback on ads that slipped through, innocent images that were
1148 blocked, and any other problems relating to the default.action file through our
1149 actions feedback mechanism located at http://www.privoxy.org/actions/. On this
1150 page, you will also find a bookmark which will take you back there from any
1151 troubled site and even pre-fill the form!
1153 New, improved default.action files will occasionally be made available based on
1154 your feedback. These will be announced on the ijbswa-announce list and
1155 available from our the files section of our project page.
1156 -------------------------------------------------------------------------------
1160 For any other issues, feel free to use the mailing lists. Technically
1161 interested users and people who wish to contribute to the project are also
1162 welcome on the developers list! You can find an overview of all Privoxy-related
1163 mailing lists, including list archives, at: http://sourceforge.net/mail/?
1165 -------------------------------------------------------------------------------
1167 7. Privoxy Copyright, License and History
1169 Copyright © 2001, 2002 by Privoxy Developers <developers@privoxy.org>
1171 Some source code is based on code Copyright © 1997 by Anonymous Coders and
1172 Junkbusters, Inc. and licensed under the GNU General Public License.
1174 Portions of this document are "borrowed" from the original Junkbuster (tm) FAQ,
1175 and modified as appropriate for Privoxy.
1176 -------------------------------------------------------------------------------
1180 Privoxy is free software; you can redistribute it and/or modify it under the
1181 terms of the GNU General Public License, version 2, as published by the Free
1182 Software Foundation.
1184 This program is distributed in the hope that it will be useful, but WITHOUT ANY
1185 WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A
1186 PARTICULAR PURPOSE. See the GNU General Public License for more details, which
1187 is available from the Free Software Foundation, Inc, 59 Temple Place - Suite
1188 330, Boston, MA 02111-1307, USA.
1190 You should have received a copy of the GNU General Public License along with
1191 this program; if not, write to the
1194 Foundation, Inc. 59 Temple Place - Suite 330
1195 Boston, MA 02111-1307
1197 -------------------------------------------------------------------------------
1201 In the beginning, there was the Internet Junkbuster, by Anonymous Coders and
1202 Junkbusters Corporation. It saved many users a lot of pain in the early days of
1203 web advertising and user tracking.
1205 But the web, its protocols and standards, and with it, the techniques for
1206 forcing users to consume ads, give up autonomy over their browsing, and for
1207 spying on them, kept evolving. Unfortunately, the Internet Junkbuster did not.
1208 Version 2.0.2, published in 1998, was (and is) the last official release
1209 available from Junkbusters Corporation. Fortunately, it had been released under
1210 the GNU GPL, which allowed further development by others.
1212 So Stefan Waldherr started maintaining an improved version of the software, to
1213 which eventually a number of people contributed patches. It could already
1214 replace banners with a transparent image, and had a first version of pop-up
1215 killing, but it was still very closely based on the original, with all its
1216 limitations, such as the lack of HTTP/1.1 support, flexible per-site
1217 configuration, or content modification. The last release from this effort was
1218 version 2.0.2-10, published in 2000.
1220 Then, some developers picked up the thread, and started turning the software
1221 inside out, upside down, and then reassembled it, adding many new features
1224 The result of this is Privoxy, whose first stable release, 3.0, is due late
1225 summer or early fall 2002.