1 Privoxy Frequently Asked Questions
5 $Id: faq.sgml,v 1.32 2002/03/27 00:57:03 hal9 Exp $
7 This FAQ gives users and developers alike answers to frequently asked questions
10 Privoxy is a web proxy with advanced filtering capabilities for protecting
11 privacy, filtering web page content, managing cookies, controlling access, and
12 removing ads, banners, pop-ups and other obnoxious Internet junk. Privoxy has a
13 very flexible configuration and can be customized to suit individual needs and
14 tastes. Privoxy has application for both stand-alone systems and multi-user
17 Privoxy is based on the code of the Internet Junkbuster. Junkbuster was
18 originally written by JunkBusters Corporation, and was released as free
19 open-source software under the GNU GPL. Stefan Waldherr made many improvements,
20 and started the SourceForge project to continue development.
22 You can find the latest version of the document at http://www.privoxy.org/faq/.
23 Please see the Contact section in the user-manual if you want to contact the
26 -------------------------------------------------------------------------------
29 1. Frequently Asked Questions
31 1.1. General Information
33 1.1.1. What is this new version of Privoxy?
34 1.1.2. Why "Privoxy"? Why a name change at all?
35 1.1.3. How does Privoxy differ from the old Junkbuster?
36 1.1.4. What are some of the new features?
37 1.1.5. What is a "proxy"? How does Privoxy work?
38 1.1.6. How does Privoxy know what is an ad, and what is not?
39 1.1.7. Can Privoxy make mistakes? This does not sound very scientific.
40 1.1.8. My browser does the same things as Privoxy. Why should I use
42 1.1.9. Is there is a license or fee? What about a warranty?
44 1.1.10. I would like to help you, what do I do?
48 1.2.1. Which browsers are supported by Privoxy?
49 1.2.2. Which operating systems are supported?
50 1.2.3. Can I install Privoxy over Junkbuster?
51 1.2.4. I just installed Privoxy. Is there anything special I have to do
53 1.2.5. What is the proxy address of Privoxy?
54 1.2.6. I just installed Privoxy, and nothing is happening. All the ads
55 are there. What's wrong?
59 1.3.1. Can I use my old config files?
60 1.3.2. What is an "actions" file?
61 1.3.3. The "actions"concept confuses me. Please list some of these
63 1.3.4. How are actions files configured? What is the easiest way to do
65 1.3.5. What are the differences between intermediate.action,
67 1.3.6. Why can I change the configuration with a browser? Does that not
68 raise security issues?
69 1.3.7. What is "default.filter"?
70 1.3.8. How can I set up Privoxy to act as a proxy for my LAN?
71 1.3.9. Instead of ads, now I get a checkerboard pattern. I don't want
73 1.3.10. Why would anybody want to see a checkerboard pattern?
74 1.3.11. I see large red banners on some pages that say "Blocked". Why
75 and how do I get rid of this?
76 1.3.12. I cannot see all of the "Blocked" page banner. All I see is a
78 1.3.13. How can I make Privoxy work with other proxies like Squid?
82 1.4.1. How much does Privoxy slow my browsing down? This has to add
83 extra time to browsing.
84 1.4.2. I noticed considerable delays in page requests compared to the
85 old Junkbuster. What's wrong?
86 1.4.3. What is the "http://p.p/"?
87 1.4.4. Do you still maintain the blocklists?
88 1.4.5. How can I submit new ads?
89 1.4.6. How can I hide my IP address?
90 1.4.7. Can Privoxy guarantee I am anonymous?
91 1.4.8. Might some things break because header information is being
93 1.4.9. Can Privoxy act as a "caching" proxy to speed up web browsing?
94 1.4.10. What about as a firewall? Can Privoxy protect me?
95 1.4.11. The Privoxy logo that replaces ads is very blocky and ugly
96 looking. Can't a better font be used?
97 1.4.12. I have large empty spaces now where ads used to be. Why?
98 1.4.13. How can Privoxy filter Secure (HTTPS) URLs?
99 1.4.14. Privoxy runs as a "server". How secure is it? Do I need to take
100 any special precautions?
101 1.4.15. How can I temporarily disable Privoxy?
105 1.5.1. I just upgraded and am getting "connection refused" with every
107 1.5.2. I just added a new rule, but the steenkin ad is still getting
109 1.5.3. One of my favorite sites does not work with Privoxy. What can I
111 1.5.4. Where and how do I submit bug reports? Feature Requests? Etc?
112 1.5.5. What time is it?
114 2. Copyright and History
117 1. Frequently Asked Questions
119 1.1. General Information
121 1.1.1. What is this new version of Privoxy?
123 The original Internet Junkbuster (tm) is a copyrighted product of Junkbusters
124 Corporation. Development of this effort stopped some time ago as of version
125 2.0.2. Stefan Waldherr started the ijbswa project on Sourceforge to rekindle
126 development. Other developers subsequently joined with Stefan, and have since
127 added many new features, refinements and enhancements. The result of this
130 Privoxy started with the same Junkbuster 2.0.2 code base, but has advanced
131 significantly at this point.
133 -------------------------------------------------------------------------------
135 1.1.2. Why "Privoxy"? Why a name change at all?
137 Privoxy is the "Privacy Enhancing Proxy".
139 There are possible legal complications from the continued use of the Junkbuster
140 name, which is a trademark of Junkbusters Corporation. (There are, however, no
141 objections from Junkbusters Corporation to the Privoxy project itself, and
142 they, in fact, still share our ideals and goals.)
144 The developers also believed that there so many changes from the original code,
145 that it was time to make a clean break from the past and make a name in their
146 own right, especially now with the pending release of version 3.0.
148 -------------------------------------------------------------------------------
150 1.1.3. How does Privoxy differ from the old Junkbuster?
152 Privoxy picks up where Junkbuster left off. All the old features remain. The
153 new Privoxy still blocks ads and banners, still manages cookies, and still
154 helps protect your privacy. But, these are all enhanced, and many new features
155 have been added, all in the same vein.
157 The configuration has changed significantly as well. This is something that
158 users will notice right off the bat. The "blocklist" file does not exist any
159 more. This is replaced by "actions" files, such as default.actions. This is
160 where most of the per site configuration is now.
162 -------------------------------------------------------------------------------
164 1.1.4. What are some of the new features?
166 * Integrated browser based configuration and control utility (http://p.p).
167 Browser-based tracing of rule and filter effects.
169 * Blocking of annoying pop-up browser windows.
171 * HTTP/1.1 compliant (most, but not all 1.1 features are supported).
173 * Support for Perl Compatible Regular Expressions in the configuration files,
174 and generally a more sophisticated and flexible configuration syntax over
179 * Web page content filtering (removes banners based on size, invisible
180 "web-bugs", JavaScript, pop-ups, status bar abuse, etc.)
182 * Bypass many click-tracking scripts (avoids script redirection).
184 * Multi-threaded (POSIX and native threads).
186 * Auto-detection and re-reading of config file changes.
188 * User-customizable HTML templates (e.g. 404 error page).
190 * Improved cookie management features (e.g. session based cookies).
192 * Builds from source on most UNIX-like systems. Packages available for: Linux
193 (RedHat, SuSE, or Debian), Windows, Sun Solaris, Mac OSX, OS/2, HP-UX 11
196 * In addition, the configuration is much more powerful and versatile
199 -------------------------------------------------------------------------------
201 1.1.5. What is a "proxy"? How does Privoxy work?
203 When you connect to a web site with Privoxy, you are really connecting to your
204 locally running version of Privoxy. Privoxy intercepts your requests for the
205 web page, and relays that to the "real" web site. The web site sends the HTTP
206 data stream back to Privoxy, where Privoxy can work its magic before it relays
207 this data back to your web browser.
209 Since Privoxy sits between you and the WWW, it is in a position to intercept
210 and completely manage all web traffic and HTTP content before it gets to your
211 browser. Privoxy uses various programming methods to do this, all of which is
212 under your control via the various configuration files and options.
214 There are many kinds of proxies. Privoxy best fits the "filtering proxy"
217 -------------------------------------------------------------------------------
219 1.1.6. How does Privoxy know what is an ad, and what is not?
221 Privoxy processes all the raw content of every web page. So it reads everything
222 on each page. It then compares this to the rules as set up in the configuration
223 files, and looks for any matches to these rules. Privoxy makes heavy use of
224 "regular expressions". (If you are not familiar with regular expressions, it is
225 explained briefly in the user manual.) Regular expressions facilitate matching
226 of one text string against another, using wildcards to build complex patterns.
227 So Privoxy will typically look for URLs and other content that match certain
228 key words and expressions as defined in the configuration files. For instance a
229 URL that contains "/banners", has a high probability of containing ad banners,
230 and thus would be a prime candidate to have a matching rule.
232 So Privoxy will look for these kinds of obvious looking culprits. And also,
233 will use lists of known organizations that specialize in ads. Again, using
234 complex patterns to match as many potential combinations as possible since
235 there tend to be many, many variations used by advertisers, and new ones are
236 being introduced all the time.
238 -------------------------------------------------------------------------------
240 1.1.7. Can Privoxy make mistakes? This does not sound very scientific.
242 Actually, it's a black art ;-) And yes, it is always possible to have a broad
243 rule accidentally block something by mistake. There is a good chance you may
244 run into such a situation at some point. It is tricky writing rules to cover
245 every conceivable possibility, and not occasionally get false positives.
247 But this should not be a big concern since the Privoxy configuration is very
248 flexible, and includes tools to help identify these types of situations so they
249 can be addressed as needed, allowing you to customize your installation. (See
252 -------------------------------------------------------------------------------
254 1.1.8. My browser does the same things as Privoxy. Why should I use Privoxy at
257 Modern browsers do indeed have some of the same functionality as Privoxy. Maybe
258 this is adequate for you. But Privoxy is much more versatile and powerful, and
259 can do a number of things that browsers just can't.
261 In addition, a proxy is good choice if you use multiple browsers, or have a LAN
262 with multiple computers. This way all the configuration is in one place, and
263 you don't have to maintain a similar configuration for possibly many browsers.
265 -------------------------------------------------------------------------------
267 1.1.9. Is there is a license or fee? What about a warranty? Registration?
269 Privoxy is licensed under the GNU General Public License (GPL). It is free to
270 use, copy, modify or distribute as you wish under the terms of this license.
271 See http://www.gnu.org/copyleft/gpl.html for specifics.
273 There is no warranty of any kind, expressed, implied or otherwise. That is
274 something that would cost real money ;-) There is no registration either.
275 Privoxy really is free in every respect!
277 -------------------------------------------------------------------------------
279 1.1.10. I would like to help you, what do I do?
281 1.1.10.1. Money Money Money
283 We, of course, welcome donations and use the money for domain registering,
284 regular world-wide get-togethers (hahaha). Anyway, we'll soon describe the
285 process how to donate money to the team.
287 -------------------------------------------------------------------------------
289 1.1.10.2. You want to work with us?
291 Well, helping the team is always a good idea. We welcome new developers, RPM
292 gurus or documentation makers. Simply get an account on sourceforge.net and
293 mail your id to the developer mailing list. Then read the section Quickstart in
294 the Developer's Manual.
296 Once we have added you to the team, you'll have write access to the CVS
297 repository, and together we'll find a suitable task for you.
299 -------------------------------------------------------------------------------
303 1.2.1. Which browsers are supported by Privoxy?
305 Any browser that can be configured to use a "proxy", which should be virtually
306 all browsers. Direct browser support is not necessary since Privoxy runs as a
307 separate application and just exchanges standard HTML data with your browser.
309 -------------------------------------------------------------------------------
311 1.2.2. Which operating systems are supported?
313 Right now Win32, Mac OSX, OS/2, AmigaOS, Linux, and many flavors of Unix.
315 Source code is available, so porting to other operating systems, is always a
318 -------------------------------------------------------------------------------
320 1.2.3. Can I install Privoxy over Junkbuster?
322 We recommend you uninstall Junkbuster first to minimize conflicts and
323 confusion. You may want to save your old configuration files for future
324 reference. The configuration is substantially changed.
326 See the user-manual for platform specific installation instructions. [FIXME:
327 This is meant for after the name change for 3.0!]
329 Note: Some installers may automatically uninstall Junkbuster, if present!
331 -------------------------------------------------------------------------------
333 1.2.4. I just installed Privoxy. Is there anything special I have to do now?
335 All browsers must be told to use Privoxy as a proxy by specifying the correct
336 proxy address and port number in the appropriate configuration area for the
337 browser. See below. Also, you should flush your browser's memory and disk cache
338 to get rid of any cached items.
340 -------------------------------------------------------------------------------
342 1.2.5. What is the proxy address of Privoxy?
344 If you set up the Privoxy to run on the computer you browse from (rather than
345 your ISP's server or some networked computer on a LAN), the proxy will be on
346 "localhost" (which is the special name used by every computer on the Internet
347 to refer to itself) and the port will be 8118 (unless you have Privoxy to run
348 on a different port with the listen-address config option).
350 When configuring your browser's proxy settings you typically enter the word
351 "localhost" in the boxes next to "HTTP" and "Secure" (HTTPS) and then the
352 number "8118" for "port". This tells your browser to send all web requests to
353 Privoxy instead of directly to the Internet.
355 Privoxy can also be used to proxy for a Local Area Network. In this case, your
356 would enter either the IP address of the LAN host where Privoxy is running, or
357 the equivalent hostname. Port assignment would be same as above.
359 Privoxy does not currently handle protocols such as FTP, SMTP, IM, IRC, ICQ, or
360 other Internet protocols.
362 -------------------------------------------------------------------------------
364 1.2.6. I just installed Privoxy, and nothing is happening. All the ads are
367 Did you configure your browser to use Privoxy as a proxy? It does not sound
368 like it. See above. You might also try flushing the browser's caches to force a
369 full re-reading of pages. You can verify that Privoxy is running, and your
370 browser is correctly configured by entering the special URL: http://p.p/. This
371 should give you a banner that says "This is Privoxy" and access to Privoxy's
372 internal configuration. If you see this, then you are good to go. If not, the
373 browser or Privoxy are not set up correctly.
375 -------------------------------------------------------------------------------
379 1.3.1. Can I use my old config files?
381 There are major changes to Junkbuster configuration from version 2.0.x to 2.9.x
382 and later. The older files will not work at all. If this is the case, you will
383 need to re-enter your old data into the new configuration structure. This is
384 probably also a good recommendation even if upgrading from 2.9.x to 3.x since
385 there were many minor changes along the way.
387 -------------------------------------------------------------------------------
389 1.3.2. What is an "actions" file?
391 "actions" files are where various actions that Privoxy might take, are
392 configured. Typically, you would define a set of default actions that apply to
393 all URLs, then add exceptions to these defaults.
395 Actions can be defined on a per site basis, or for groups of sites. Actions can
396 also be grouped together and then applied to one or more sites. There are many
397 possible actions that might apply to any given site. As an example, if we are
398 blocking cookies as one of our default actions, but need to accept cookies from
399 a given site, we would define this in our "actions" file.
401 Privoxy comes with several default actions files, with varying degrees of
402 filtering and blocking, as starting points for your own configuration (see
405 -------------------------------------------------------------------------------
407 1.3.3. The "actions"concept confuses me. Please list some of these "actions".
409 These are all explained in the user-manual. Please refer to that.
411 -------------------------------------------------------------------------------
413 1.3.4. How are actions files configured? What is the easiest way to do this?
415 The easiest way to do this, is to access Privoxy with your web browser at http:
416 //p.p/, and then select "Edit the actions list" from the selection list. You
417 can also do this by editing the appropriate file with a text editor.
419 Please see the user-manual for a detailed explanation of these and other
420 configuration files, and their various options and syntax.
422 -------------------------------------------------------------------------------
424 1.3.5. What are the differences between intermediate.action, basic.action,
427 Configuring Privoxy is not easy. To help you get started, we provide you with
428 three different default configurations. The following table shows you, which
429 features are enabled in each configuration.
431 Table 1. Default Configurations
433 +--------------------------------------------------------------------------------------+
434 |Feature |default.action|basic.action |intermediate.action|advanced.action|
435 |--------------------+--------------+--------------+-------------------+---------------|
436 |ad-filtering |? |x |x |x |
437 |--------------------+--------------+--------------+-------------------+---------------|
438 |blank image |? |x |x |x |
439 |--------------------+--------------+--------------+-------------------+---------------|
440 |de-animate GIFs |? |x |x |x |
441 |--------------------+--------------+--------------+-------------------+---------------|
442 |referer forging |? |x |x |x |
443 |--------------------+--------------+--------------+-------------------+---------------|
445 |+no-cookies-keep | | | | |
446 |(i.e. session | | | | |
447 |cookies only) | | | | |
448 |--------------------+--------------+--------------+-------------------+---------------|
449 |no-popup windows |? | |x |x |
450 |--------------------+--------------+--------------+-------------------+---------------|
451 |fast redirects |? | |x |x |
452 |--------------------+--------------+--------------+-------------------+---------------|
453 |hide-referrer |? | |x |x |
454 |--------------------+--------------+--------------+-------------------+---------------|
455 |hide-useragent |? | |x |x |
456 |--------------------+--------------+--------------+-------------------+---------------|
457 |content-modification|? | | |x |
458 |--------------------+--------------+--------------+-------------------+---------------|
459 |feature-x |? | | | |
460 |--------------------+--------------+--------------+-------------------+---------------|
461 |feature-y |? | | | |
462 |--------------------+--------------+--------------+-------------------+---------------|
463 |feature-z |? | | | |
464 +--------------------------------------------------------------------------------------+
466 -------------------------------------------------------------------------------
468 1.3.6. Why can I change the configuration with a browser? Does that not raise
471 What I don't understand, is how I can browser edit the config file as a regular
472 user, while the whole /etc/privoxy hierarchy belongs to the user "privoxy",
475 When you use the browser-based editor, Privoxy itself is writing to the config
476 files. Because Privoxy is running as the user "privoxy", it can update the
479 If you don't like this, setting "enable-edit-actions 0" in the config file will
480 disable the browser-based editor. If you're that paranoid, you should also
481 consider setting "enable-remote-toggle 0" to prevent browser-based enabling/
482 disabling of Privoxy.
484 Note that normally only local users can connect to Privoxy, so this is not
485 (normally) a security problem.
487 -------------------------------------------------------------------------------
489 1.3.7. What is "default.filter"?
491 The "default.filter" file is used to "filter" any web page content. By
492 "filtering" we mean it can modify, remove, or change anything on the page,
493 including HTML tags, and JavaScript. Regular expressions are used to accomplish
494 this, and operate on a line by line basis. This is potentially a very powerful
495 feature, but requires some expertise.
497 If you are familiar with regular expressions, and HTML, you can look at the
498 provided default.filter with a text editor and see some of things it can be
501 Presently, there is no GUI editor option for this part of the configuration,
502 but you can disable/enable various sections of the included default file with
503 the "Actions List Editor" from your browser.
505 -------------------------------------------------------------------------------
507 1.3.8. How can I set up Privoxy to act as a proxy for my LAN?
509 By default, Privoxy only responds to requests from localhost. To have it act as
510 a server for a network, this needs to be changed in the main config file where
511 the Privoxy configuration is located. In that file is a "listen-address"
512 option. It may be commented out with a "#" symbol. Make sure it is uncommented,
513 and assign it the address of the LAN gateway interface, and port number to use:
515 listen-address 192.168.1.1:8118
518 Save the file, and restart Privoxy. Configure all browsers on the network then
519 to use this address and port number.
521 -------------------------------------------------------------------------------
523 1.3.9. Instead of ads, now I get a checkerboard pattern. I don't want to see
526 This is a configuration option for images that Privoxy is stopping. You have
527 the choice of a checkerboard pattern, a transparent 1x1 GIF image (aka
528 "blank"), or a custom URL of your choice. Note that to fit this category, the
529 URL must match both the "+image" and "+block" actions.
531 If you want to see nothing, then change the "+image-blocker" action to
532 "+image-blocker{blank}". This can be done from the "Edit Actions List"
533 selection at http://p.p/. Or by hand editing the appropriate actions file. This
534 will only effect what is defined as "images" though. Also, any URLs that
535 generate the bright red "Blocked" banner, can be moved to the "+image-blocker"
536 section for the same reason.
538 -------------------------------------------------------------------------------
540 1.3.10. Why would anybody want to see a checkerboard pattern?
542 This can be helpful for troubleshooting problems. It might also be good for
543 anyone new to Privoxy so that they can see if their favorite pages are
544 displaying correctly, and Privoxy is not inadvertently removing something
547 -------------------------------------------------------------------------------
549 1.3.11. I see large red banners on some pages that say "Blocked". Why and how
550 do I get rid of this?
552 These are URLs that match something in one of Privoxy's block actions (+block).
553 It is meant to be a warning so that you know something has been blocked and an
554 easy way for you to see why. These are handled differently than what has been
555 defined explicitly as "images" (e.g. ad banners). Depending on the URL itself,
556 it is sometimes hard for Privoxy to really know whether it is indeed an ad
559 If you want them to be treated as if they were images, so that they can be made
560 invisible, then move the offending URL from the "+block" section to the
561 "+imageblock" section of your actions file. Just be forewarned, if make any URL
562 is made "invisible", you may not have any inkling that something has been
563 removed from that page.
565 Alternately, you could modify the "block" HTML template that is used by Privoxy
566 to display this, and make it something more to your liking.
568 -------------------------------------------------------------------------------
570 1.3.12. I cannot see all of the "Blocked" page banner. All I see is a bright
573 There is not enough space to fit the entire page. Try right clicking on the
574 visible, red portion, and select "Show Frame", or equivalent. This will usually
575 allow you to see the entire Privoxy "Blocked" page, and from there you can see
576 just what is being blocked, and why.
578 -------------------------------------------------------------------------------
580 1.3.13. How can I make Privoxy work with other proxies like Squid?
582 This can be done. See the user manual, which describes how to do this.
584 -------------------------------------------------------------------------------
588 1.4.1. How much does Privoxy slow my browsing down? This has to add extra time
591 It should not slow you down any in real terms, and may actually help speed
592 things up since ads, banners and other junk are not being displayed. The actual
593 processing time required by Privoxy itself for each page, is relatively small
594 in the overall scheme of things, and happens very quickly. This is typically
595 more than offset by time saved not downloading and rendering ad images.
597 "Filtering" via the filterfile mechanism may cause a perceived slowdown, since
598 the entire page is buffered before displaying. See below.
600 -------------------------------------------------------------------------------
602 1.4.2. I noticed considerable delays in page requests compared to the old
603 Junkbuster. What's wrong?
605 Using the default filtering configuration, I noticed considerable delays in
606 page requests compared to the old Junkbuster. Loading pages with large contents
607 seemed to take forever, then suddenly delivering all the content at once.
609 The whole content must be loaded in order to filter, and nothing is is sent to
610 the browser during this time. The loading time does not really change in real
611 numbers, but the feeling is different, because most browsers are able to start
612 rendering incomplete content, giving the user a feeling of "it works".
614 To modify the content of a page (i.e. make frames resizeable again, etc.) and
615 not just replace ads, Privoxy needs to download the entire page first, do its
616 content magic and then send the page to the browser.
618 -------------------------------------------------------------------------------
620 1.4.3. What is the "http://p.p/"?
622 Since Privoxy sits between your web browser and the Internet, it can be
623 programmed to handle certain pages specially.
625 With recent versions of Privoxy (version 2.9.x), you can get some information
626 about Privoxy and change some settings by going to http://p.p/ or,
627 equivalently, http://www.privoxy.org/config/ (Note that p.p is far easier to
628 type but may not work in some configurations).
630 These pages are *not* forwarded to a server on the Internet - instead they are
631 handled by a special web server which is built in to Privoxy.
633 If you are not running Privoxy, then http://p.p/ will fail, and http://
634 www.privoxy.org/config/ will return a web page telling you you're not running
637 If you have version 2.0.2, then the equivalent is http://example.com/
638 show-proxy-args (but you get far less information, and you should really
639 consider upgrading to 2.9.x).
641 -------------------------------------------------------------------------------
643 1.4.4. Do you still maintain the blocklists?
645 No. The format of the blocklists has changed significantly in the versions
646 2.9.x. Once we have released the new version, there will again be blocklists
647 that you can update automatically.
649 -------------------------------------------------------------------------------
651 1.4.5. How can I submit new ads?
653 As of now, please discontinue to submit new ad blocking infos. Once we have
654 released the new version, there will again be a form on the website, which you
655 can use to contribute new ads.
657 -------------------------------------------------------------------------------
659 1.4.6. How can I hide my IP address?
661 You cannot hide your IP address with Privoxy or any other software, since the
662 server needs to know your IP address to send the answer to you.
664 Fortunately there are many publicly usable anonymous proxies out there, which
665 solve the problem by providing a further level of indirection between you and
666 the web server, shared by many people and thus letting your requests "drown" in
667 white noise of unrelated requests as far as user tracking is concerned.
669 Most of them will, however, log your IP address and make it available to the
670 authorities in case you abuse that anonymity for criminal purposes. In fact you
671 can't even rule out that some of them only exist to *collect* information on
672 (those suspicious) people with a more than average preference for privacy.
674 You can find a list of anonymous public proxies at multiproxy.org and many more
677 -------------------------------------------------------------------------------
679 1.4.7. Can Privoxy guarantee I am anonymous?
681 No. Your chances of remaining anonymous are greatly improved, but unless you
682 are an expert on Internet security it would be safest to assume that everything
683 you do on the Web can be traced back to you.
685 Privoxy can remove various information about you, and allows you more freedom
686 to decide which sites you can trust. But it's still possible that web sites can
687 find out who you are. Here's one way this can happen.
689 A few browsers disclose the user's email address in certain situations, such as
690 when transferring a file by FTP. Privoxy does not filter FTP. If you need this
691 feature, or are concerned about the mail handler of your browser disclosing
692 your email address, you might consider products such as NSClean.
694 Browsers available only as binaries could use non-standard headers to give out
695 any information they can have access to: see the manufacturer's license
696 agreement. It's impossible to anticipate and prevent every breach of privacy
697 that might occur. The professionally paranoid prefer browsers available as
698 source code, because anticipating their behavior is easier. Trust the source,
701 -------------------------------------------------------------------------------
703 1.4.8. Might some things break because header information is being altered?
705 Definitely. More and more sites use HTTP header content to decide what to
706 display and how to display it. There is many ways that this can be handled, so
707 having hard and fast rules, is tricky.
709 "USER AGENT" in particular is often used in this way to identify the browser,
710 and adjust content accordingly. Changing this now is not recommended, since so
711 many sites do look for this. You may get undesirable results by changing this.
713 For instance, different browsers use different encodings of Russian and Czech
714 characters, certain web servers convert pages on-the-fly according to the User
715 Agent header. Giving a "User Agent" with the wrong operating system or browser
716 manufacturer causes some sites in these languages to be garbled; Surfers to
717 Eastern European sites should change it to something closer. And then some page
718 access counters work by looking at the "REFERER" header; they may fail or break
719 if unavailable. The weather maps of Intellicast have been blocked by their
720 server when no "REFERER" or cookie is provided, is another example. There are
721 many, many other ways things can go wrong when trying to fool a web server.
723 If you have problems with a site, you will have to adjust your configuration
724 accordingly. Cookies are probably the most likely adjustment that may be
725 required, but by no means the only one.
727 -------------------------------------------------------------------------------
729 1.4.9. Can Privoxy act as a "caching" proxy to speed up web browsing?
731 No, it does not have this ability at all. You want something like Squid for
732 this. And, yes, before you ask, Privoxy can co-exist with other kinds of
735 -------------------------------------------------------------------------------
737 1.4.10. What about as a firewall? Can Privoxy protect me?
739 Not in the way you mean, or in the way a true firewall can, or a proxy that has
740 this specific capability. Privoxy can help protect your privacy, but not really
741 protect you from intrusion attempts.
743 -------------------------------------------------------------------------------
745 1.4.11. The Privoxy logo that replaces ads is very blocky and ugly looking.
746 Can't a better font be used?
748 This is not a font problem. The logo is an image that is created by Privoxy on
749 the fly. So as to not waste memory, the image is rather small. The blockiness
750 comes when the image is scaled to fill a largish area. There is not much to be
751 done about this, other than to use one of the other "imageblock" directives:
752 pattern, blank, or a URL of your choosing.
754 Given the above problem, we have decided to remove the logo option entirely [as
757 -------------------------------------------------------------------------------
759 1.4.12. I have large empty spaces now where ads used to be. Why?
761 It would be easy enough to just eliminate this space altogether, rather than
762 fill it with blank space. But, this would create problems with many pages that
763 use the overall size of the ad to help organize the page layout and position
764 the various components of the page where they were intended to be. It is best
767 -------------------------------------------------------------------------------
769 1.4.13. How can Privoxy filter Secure (HTTPS) URLs?
771 This is a limitation since HTTPS transactions are encrypted SSL sessions
772 between your browser and the secure site, and are meant to be reliably secure
773 and private. This means that all cookies and HTTP header information are also
774 encrypted from the time they leave your browser, to the site, and vice versa.
775 Privoxy does not try to unencrypt this information, so it just passes through
776 as is. Privoxy can still catch images and ads that are embedded in the SSL
779 -------------------------------------------------------------------------------
781 1.4.14. Privoxy runs as a "server". How secure is it? Do I need to take any
784 There are no known exploits that might effect Privoxy. On Unix-like systems,
785 Privoxy can run as a non-privileged user, which is how we recommend it be run.
786 Also, by default Privoxy only listens to requests from "localhost". The server
787 aspect of Privoxy is not itself directly exposed to the Internet in this
788 configuration. If you want to have Privoxy serve as a LAN proxy, this will have
789 to be opened up to allow for LAN requests. In this case, we'd recommend you
790 specify only the LAN gateway address, e.g. 192.168.1.1, in the main Privoxy
791 config file. All LAN hosts can then use this as their proxy address in the
792 browser proxy configuration. In this way, Privoxy will not listen on any
793 external ports. Of course, a firewall is always good too. Better safe than
796 -------------------------------------------------------------------------------
798 1.4.15. How can I temporarily disable Privoxy?
800 The easiest way is to access Privoxy with your browser by using the special
801 URL: http://p.p/ and select "Toggle Privoxy on or off" from that page.
803 -------------------------------------------------------------------------------
807 1.5.1. I just upgraded and am getting "connection refused" with every web page?
809 Either Privoxy is not running, or your browser is configured for a different
810 port than what Privoxy is using.
812 The old Privoxy (and also Junkbuster) used port 8000 by default. This has been
813 changed to port 8118 now, due to a conflict with NAS (Network Audio Service),
814 which uses port 8000. If you haven't, you need to change your browser to the
815 new port number, or alternately change Privoxy's "listen-address" setting in
816 the config file used to start Privoxy.
818 -------------------------------------------------------------------------------
820 1.5.2. I just added a new rule, but the steenkin ad is still getting through.
823 If the ad had been displayed before you added its URL, it will probably be held
824 in the browser's cache for some time, so it will be displayed without the need
825 for any request to the server, and Privoxy will not be in the picture. The best
826 thing to do is try flushing the browser's caches. And then try again.
828 If this doesn't help, you probably have an error in the rule you applied. Try
829 pasting the full URL of the offending ad into http://www.privoxy.org/config/
830 show-url-info and see if any actions match your new rule.
832 -------------------------------------------------------------------------------
834 1.5.3. One of my favorite sites does not work with Privoxy. What can I do?
836 First verify that it is indeed a Privoxy problem, by disabling Privoxy
837 filtering and blocking. Go to http://p.p/ and click on "Toggle Privoxy On or
838 Off", then disable it. Now try that page again.
840 If still a problem, go to "Show which actions apply to a URL and why" from
841 http://p.p/ and paste the full URL of the page in question into the prompt. See
842 which actions are being applied to the URL. Now, armed with this information,
843 go to "Edit the actions list". Here you should see various sections that have
844 various Privoxy features disabled for specific sites. Disabled "actions" will
845 have a "-" (minus sign) in front of them. Add your problem page URL to one of
846 these sections that looks like it is disabling the feature that is causing the
847 problem. Re-try the page. There might be some trial and error involved. This is
848 discussed in a little more detail in the user-manual appendix.
850 Alternately, if you are comfortable with a text editor, you can accomplish the
851 same thing by editing the appropriate "actions" file.
853 -------------------------------------------------------------------------------
855 1.5.4. Where and how do I submit bug reports? Feature Requests? Etc?
857 Feedback is encouraged, whether good, bad or ugly. Please see the contact page
858 in the user-manual for details.
860 -------------------------------------------------------------------------------
862 1.5.5. What time is it?
866 -------------------------------------------------------------------------------
868 2. Copyright and History
870 Please see the user-manual for information on Copyright and History.
872 -------------------------------------------------------------------------------
876 Please see the user-manual for others references.