1 <!DOCTYPE article PUBLIC "-//OASIS//DTD DocBook V3.1//EN" [
2 <!entity % dummy "IGNORE">
3 <!entity supported SYSTEM "supported.sgml">
4 <!entity newfeatures SYSTEM "newfeatures.sgml">
5 <!entity p-intro SYSTEM "privoxy.sgml">
6 <!entity seealso SYSTEM "seealso.sgml">
7 <!entity buildsource SYSTEM "buildsource.sgml">
8 <!entity contacting SYSTEM "contacting.sgml">
9 <!entity history SYSTEM "history.sgml">
10 <!entity copyright SYSTEM "copyright.sgml">
11 <!entity license SYSTEM "license.sgml">
12 <!entity GPLv2 SYSTEM "../../LICENSE">
13 <!entity p-authors SYSTEM "p-authors.sgml">
14 <!entity config SYSTEM "p-config.sgml">
15 <!entity changelog SYSTEM "changelog.sgml">
16 <!entity p-version "3.0.27">
17 <!entity p-status "UNRELEASED">
18 <!entity % p-authors-formal "INCLUDE"> <!-- include additional text, etc -->
19 <!entity % p-not-stable "INCLUDE">
20 <!entity % p-stable "IGNORE">
21 <!entity % p-text "IGNORE"> <!-- define we are not a text only doc -->
22 <!entity % p-doc "INCLUDE"> <!-- and we are a formal doc -->
23 <!entity % p-readme "IGNORE">
24 <!entity % user-man "IGNORE">
25 <!entity % config-file "IGNORE">
26 <!entity % p-supp-userman "IGNORE"> <!-- Omit some from supported.sgml -->
27 <!entity my-copy "©"> <!-- kludge for docbook2man -->
28 <!entity % draft "IGNORE"> <!-- WIP stuff -->
29 <!entity % seealso-extra "INCLUDE"> <!-- extra stuff from seealso.sgml -->
30 <!entity my-app "<application>Privoxy</application>">
33 File : $Source: /cvsroot/ijbswa/current/doc/source/user-manual.sgml,v $
36 This file belongs into
37 ijbswa.sourceforge.net:/home/groups/i/ij/ijbswa/htdocs/
39 Copyright (C) 2001-2017 Privoxy Developers https://www.privoxy.org/
42 ========================================================================
43 NOTE: Please read developer-manual/documentation.html before touching
44 anything in this, or other Privoxy documentation.
45 ========================================================================
52 <title>Privoxy &p-version; User Manual</title>
56 <!-- Completely the wrong markup, but very little is allowed -->
57 <!-- in this part of an article. FIXME -->
58 <link linkend="copyright">Copyright</link> &my-copy; 2001-2017 by
59 <ulink url="https://www.privoxy.org/">Privoxy Developers</ulink>
63 <pubdate>$Id: user-manual.sgml,v 2.221 2017/05/20 09:27:54 fabiankeil Exp $</pubdate>
67 Note: the following should generate a separate page, and a live link to it,
68 all nicely done. But it doesn't for some mysterious reason. Please leave
69 commented unless it can be fixed proper. For the time being, the
70 copyright/license declarations will be in their own sgml.
83 This is here to keep vim syntax file from breaking :/
84 If I knew enough to fix it, I would.
85 PLEASE DO NOT REMOVE! HB: hal@foobox.net
91 The <citetitle>Privoxy User Manual</citetitle> gives users information on how to
92 install, configure and use <ulink
93 url="https://www.privoxy.org/">Privoxy</ulink>.
96 <!-- Include privoxy.sgml boilerplate: -->
98 <!-- end privoxy.sgml -->
101 You can find the latest version of the <citetitle>Privoxy User Manual</citetitle> at <ulink
102 url="https://www.privoxy.org/user-manual/">https://www.privoxy.org/user-manual/</ulink>.
103 Please see the <link linkend="contact">Contact section</link> on how to
104 contact the developers.
111 <!-- ~~~~~ New section ~~~~~ -->
112 <sect1 label="1" id="introduction"><title>Introduction</title>
114 This documentation is included with the current &p-status; version of
115 <application>Privoxy</application>, &p-version;<![%p-not-stable;[,
116 and is mostly complete at this point. The most up to date reference for the
117 time being is still the comments in the source files and in the individual
118 configuration files. Development of a new version is currently nearing
119 completion, and includes significant changes and enhancements over
123 <!-- include only in non-stable versions -->
126 Since this is a &p-status; version, not all new features are well tested. This
127 documentation may be slightly out of sync as a result (especially with
128 CVS sources). And there <emphasis>may be</emphasis> bugs, though hopefully
133 <!-- ~~~~~ New section ~~~~~ -->
134 <sect2 id="features"><title>Features</title>
136 In addition to the core
137 features of ad blocking and
138 <ulink url="http://en.wikipedia.org/wiki/Browser_cookie">cookie</ulink> management,
139 <application>Privoxy</application> provides many supplemental
140 features<![%p-not-stable;[, some of them currently under development]]>,
141 that give the end-user more control, more privacy and more freedom:
143 <!-- Include newfeatures.sgml boilerplate here: -->
145 <!-- end boilerplate -->
150 <!-- ~ End section ~ -->
153 <!-- ~~~~~ New section ~~~~~ -->
154 <sect1 id="installation"><title>Installation</title>
157 <application>Privoxy</application> is available both in convenient pre-compiled
158 packages for a wide range of operating systems, and as raw source code.
159 For most users, we recommend using the packages, which can be downloaded from our
160 <ulink url="https://sourceforge.net/projects/ijbswa/">Privoxy Project
166 On some platforms, the installer may remove previously installed versions, if
167 found. (See below for your platform). In any case <emphasis>be sure to backup
168 your old configuration if it is valuable to you.</emphasis> See the <link
169 linkend="upgradersnote">note to upgraders</link> section below.
172 <!-- ~~~~~ New section ~~~~~ -->
173 <sect2 id="installation-packages"><title>Binary Packages</title>
175 How to install the binary packages depends on your operating system:
178 <!-- XXX: The installation sections should be sorted -->
180 <!-- ~~~~~ New section ~~~~~ -->
181 <sect3 id="installation-deb"><title>Debian and Ubuntu</title>
183 DEBs can be installed with <literal>apt-get install privoxy</literal>,
184 and will use <filename>/etc/privoxy</filename> for the location of
189 <!-- ~~~~~ New section ~~~~~ -->
190 <sect3 id="installation-pack-win"><title>Windows</title>
193 Just double-click the installer, which will guide you through
194 the installation process. You will find the configuration files
195 in the same directory as you installed <application>Privoxy</application> in.
198 Version 3.0.5 beta introduced full <application>Windows</application> service
199 functionality. On Windows only, the <application>Privoxy</application>
200 program has two new command line arguments to install and uninstall
201 <application>Privoxy</application> as a <emphasis>service</emphasis>.
205 <term>Arguments:</term>
208 <replaceable class="parameter">--install</replaceable>[:<replaceable class="parameter">service_name</replaceable>]
211 <replaceable class="parameter">--uninstall</replaceable>[:<replaceable class="parameter">service_name</replaceable>]
217 After invoking <application>Privoxy</application> with
218 <command>--install</command>, you will need to bring up the
219 <application>Windows</application> service console to assign the user you
220 want <application>Privoxy</application> to run under, and whether or not you
221 want it to run whenever the system starts. You can start the
222 <application>Windows</application> services console with the following
223 command: <command>services.msc</command>. If you do not take the manual step
224 of modifying <application>Privoxy's</application> service settings, it will
225 not start. Note too that you will need to give Privoxy a user account that
226 actually exists, or it will not be permitted to
227 write to its log and configuration files.
232 <!-- ~~~~~ New section ~~~~~ -->
233 <sect3 id="installation-os2"><title>OS/2</title>
236 First, make sure that no previous installations of
237 <application>Junkbuster</application> and / or
238 <application>Privoxy</application> are left on your
239 system. Check that no <application>Junkbuster</application>
240 or <application>Privoxy</application> objects are in
246 Then, just double-click the WarpIN self-installing archive, which will
247 guide you through the installation process. A shadow of the
248 <application>Privoxy</application> executable will be placed in your
249 startup folder so it will start automatically whenever OS/2 starts.
253 The directory you choose to install <application>Privoxy</application>
254 into will contain all of the configuration files.
258 <!-- ~~~~~ New section ~~~~~ -->
259 <sect3 id="installation-mac"><title>Mac OS X</title>
261 Installation instructions for the OS X platform depend upon whether
262 you downloaded a ready-built installation package (.pkg or .mpkg) or have
263 downloaded the source code.
266 <sect3 renderas="sect4" id="OS-X-install-from-package">
267 <title>Installation from ready-built package</title>
269 The downloaded file will either be a .pkg (for OS X 10.5 upwards) or a bzipped
270 .mpkg file (for OS X 10.4). The former can be double-clicked as is and the
271 installation will start; double-clicking the latter will unzip the .mpkg file
272 which can then be double-clicked to commence the installation.
275 The privoxy service will automatically start after a successful installation
276 (and thereafter every time your computer starts up) however you will need to
277 configure your web browser(s) to use it. To do so, configure them to use a
278 proxy for HTTP and HTTPS at the address 127.0.0.1:8118.
281 To prevent the privoxy service from automatically starting when your computer
282 starts up, remove or rename the file <literal>/Library/LaunchDaemons/org.ijbswa.privoxy.plist</literal>
283 (on OS X 10.5 and higher) or the folder named
284 <literal>/Library/StartupItems/Privoxy</literal> (on OS X 10.4 'Tiger').
287 To manually start or stop the privoxy service, use the scripts startPrivoxy.sh
288 and stopPrivoxy.sh supplied in /Applications/Privoxy. They must be run from an
289 administrator account, using sudo.
292 To uninstall, run /Applications/Privoxy/uninstall.command as sudo from an
293 administrator account.
296 <sect3 renderas="sect4" id="OS-X-install-from-source">
297 <title>Installation from source</title>
299 To build and install the Privoxy source code on OS X you will need to obtain
300 the macsetup module from the Privoxy Sourceforge CVS repository (refer to
301 Sourceforge help for details of how to set up a CVS client to have read-only
302 access to the repository). This module contains scripts that leverage the usual
303 open-source tools (available as part of Apple's free of charge Xcode
304 distribution or via the usual open-source software package managers for OS X
305 (MacPorts, Homebrew, Fink etc.) to build and then install the privoxy binary
306 and associated files. The macsetup module's README file contains complete
307 instructions for its use.
310 The privoxy service will automatically start after a successful installation
311 (and thereafter every time your computer starts up) however you will need to
312 configure your web browser(s) to use it. To do so, configure them to use a
313 proxy for HTTP and HTTPS at the address 127.0.0.1:8118.
316 To prevent the privoxy service from automatically starting when your computer
317 starts up, remove or rename the file <literal>/Library/LaunchDaemons/org.ijbswa.privoxy.plist</literal>
318 (on OS X 10.5 and higher) or the folder named
319 <literal>/Library/StartupItems/Privoxy</literal> (on OS X 10.4 'Tiger').
322 To manually start or stop the privoxy service, use the Privoxy Utility
323 for Mac OS X (also part of the macsetup module). This application can start
324 and stop the privoxy service and display its log and configuration files.
327 To uninstall, run the macsetup module's uninstall.sh as sudo from an
328 administrator account.
332 <!-- ~~~~~ New section ~~~~~ -->
333 <sect3 id="installation-freebsd"><title>FreeBSD</title>
336 Privoxy is part of FreeBSD's Ports Collection, you can build and install
337 it with <literal>cd /usr/ports/www/privoxy; make install clean</literal>.
343 <!-- ~~~~~ New section ~~~~~ -->
344 <sect2 id="installation-source"><title>Building from Source</title>
347 The most convenient way to obtain the <application>Privoxy</application> sources
348 is to download the source tarball from our
349 <ulink url="https://sourceforge.net/projects/ijbswa/files/Sources/">project download
354 If you like to live on the bleeding edge and are not afraid of using
355 possibly unstable development versions, you can check out the up-to-the-minute
356 version directly from <ulink url="https://sourceforge.net/p/ijbswa/code/?source=navbar">the
357 CVS repository</ulink>.
359 deprecated...out of business.
360 or simply download <ulink
361 url="http://cvs.sourceforge.net/cvstarballs/ijbswa-cvsroot.tar.bz2">the nightly CVS
366 <!-- include buildsource.sgml boilerplate: -->
368 <!-- end boilerplate -->
371 <!-- ~~~~~ New section ~~~~~ -->
372 <sect2 id="installation-keepupdated"><title>Keeping your Installation Up-to-Date</title>
375 If you wish to receive an email notification whenever we release updates of
376 <application>Privoxy</application> or the actions file, <ulink
377 url="https://lists.privoxy.org/mailman/listinfo/privoxy-announce">subscribe
378 to our announce mailing list</ulink>, privoxy-announce@lists.privoxy.org.
382 In order not to lose your personal changes and adjustments when updating
383 to the latest <literal>default.action</literal> file we <emphasis>strongly
384 recommend</emphasis> that you use <literal>user.action</literal> and
385 <literal>user.filter</literal> for your local
386 customizations of <application>Privoxy</application>. See the <link
387 linkend="actions-file">Chapter on actions files</link> for details.
395 <!-- ~ End section ~ -->
397 <!-- ~~~~~ New section ~~~~~ -->
398 <sect1 id="whatsnew">
399 <title>What's New in this Release</title>
403 <!-- ~~~~~ New section ~~~~~ -->
405 <sect2 id="upgradersnote">
406 <title>Note to Upgraders</title>
409 A quick list of things to be aware of before upgrading from earlier
410 versions of <application>Privoxy</application>:
418 The recommended way to upgrade &my-app; is to backup your old
419 configuration files, install the new ones, verify that &my-app;
420 is working correctly and finally merge back your changes using
421 <application>diff</application> and maybe <application>patch</application>.
424 There are a number of new features in each &my-app; release and
425 most of them have to be explicitly enabled in the configuration
426 files. Old configuration files obviously don't do that and due
427 to syntax changes using old configuration files with a new
428 &my-app; isn't always possible anyway.
433 Note that some installers remove earlier versions completely,
434 including configuration files, therefore you should really save
435 any important configuration files!
440 On the other hand, other installers don't overwrite existing configuration
441 files, thinking you will want to do that yourself.
446 In the default configuration only fatal errors are logged now.
447 You can change that in the <link linkend="DEBUG">debug section</link>
448 of the configuration file. You may also want to enable more verbose
449 logging until you verified that the new &my-app; version is working
456 Three other config file settings are now off by default:
457 <link linkend="enable-remote-toggle">enable-remote-toggle</link>,
458 <link linkend="enable-remote-http-toggle">enable-remote-http-toggle</link>,
459 and <link linkend="enable-edit-actions">enable-edit-actions</link>.
460 If you use or want these, you will need to explicitly enable them, and
461 be aware of the security issues involved.
468 What constitutes a <quote>default</quote> configuration has changed,
469 and you may want to review which actions are <quote>on</quote> by
470 default. This is primarily a matter of emphasis, but some features
471 you may have been used to, may now be <quote>off</quote> by default.
472 There are also a number of new actions and filters you may want to
473 consider, most of which are not fully incorporated into the default
474 settings as yet (see above).
481 The default actions setting is now <literal>Cautious</literal>. Previous
482 releases had a default setting of <literal>Medium</literal>. Experienced
483 users may want to adjust this, as it is fairly conservative by &my-app;
484 standards and past practices. See <ulink
485 url="http://config.privoxy.org/edit-actions-list?f=default">
486 http://config.privoxy.org/edit-actions-list?f=default</ulink>. New users
487 should try the default settings for a while before turning up the volume.
493 The default setting has filtering turned <emphasis>off</emphasis>, which
494 subsequently means that compression is <emphasis>on</emphasis>. Remember
495 that filtering does not work on compressed pages, so if you use, or want to
496 use, filtering, you will need to force compression off. Example:
500 { +<link linkend="filter">filter</link>{google} +<link linkend="prevent-compression">prevent-compression</link> }
504 Or if you use a number of filters, or filter many sites, you may just want
505 to turn off compression for all sites in
506 <filename>default.action</filename> (or
507 <filename>user.action</filename>).
514 Also, <link linkend="SESSION-COOKIES-ONLY">session-cookies-only</link> is
515 off by default now. If you've liked this feature in the past, you may want
516 to turn it back on in <filename>user.action</filename> now.
523 Some installers may not automatically start
524 <application>Privoxy</application> after installation.
535 <!-- ~~~~~ New section ~~~~~ -->
536 <sect1 id="quickstart"><title>Quickstart to Using Privoxy</title>
542 Install <application>Privoxy</application>. See the <link
543 linkend="installation">Installation Section</link> below for platform specific
550 Advanced users and those who want to offer <application>Privoxy</application>
551 service to more than just their local machine should check the <link
552 linkend="config">main config file</link>, especially the <link
553 linkend="access-control">security-relevant</link> options. These are
560 Start <application>Privoxy</application>, if the installation program has
561 not done this already (may vary according to platform). See the section
562 <link linkend="startup">Starting <application>Privoxy</application></link>.
568 Set your browser to use <application>Privoxy</application> as HTTP and
569 HTTPS (SSL) <ulink url="http://en.wikipedia.org/wiki/Proxy_server">proxy</ulink>
570 by setting the proxy configuration for address of
571 <literal>127.0.0.1</literal> and port <literal>8118</literal>.
572 <emphasis>DO NOT</emphasis> activate proxying for <literal>FTP</literal> or
573 any protocols besides HTTP and HTTPS (SSL) unless you intend to prevent your
574 browser from using these protocols.
580 Flush your browser's disk and memory caches, to remove any cached ad images.
581 If using <application>Privoxy</application> to manage
582 <ulink url="http://en.wikipedia.org/wiki/Browser_cookie">cookies</ulink>,
583 you should remove any currently stored cookies too.
589 A default installation should provide a reasonable starting point for
590 most. There will undoubtedly be occasions where you will want to adjust the
591 configuration, but that can be dealt with as the need arises. Little
592 to no initial configuration is required in most cases, you may want
594 <ulink url="config.html#ENABLE-EDIT-ACTIONS">web-based action editor</ulink> though.
595 Be sure to read the warnings first.
598 See the <link linkend="configuration">Configuration section</link> for more
599 configuration options, and how to customize your installation.
600 You might also want to look at the <link
601 linkend="quickstart-ad-blocking">next section</link> for a quick
602 introduction to how <application>Privoxy</application> blocks ads and
609 If you experience ads that slip through, innocent images that are
610 blocked, or otherwise feel the need to fine-tune
611 <application>Privoxy's</application> behavior, take a look at the <link
612 linkend="actions-file">actions files</link>. As a quick start, you might
613 find the <link linkend="act-examples">richly commented examples</link>
614 helpful. You can also view and edit the actions files through the <ulink
615 url="http://config.privoxy.org">web-based user interface</ulink>. The
616 Appendix <quote><link linkend="actionsanat">Troubleshooting: Anatomy of an
617 Action</link></quote> has hints on how to understand and debug actions that
618 <quote>misbehave</quote>.
624 Please see the section <link linkend="contact">Contacting the
625 Developers</link> on how to report bugs, problems with websites or to get
632 Now enjoy surfing with enhanced control, comfort and privacy!
640 <!-- ~~~~~ New section ~~~~~ -->
642 <sect2 id="quickstart-ad-blocking">
643 <title>Quickstart to Ad Blocking</title>
645 NOTE: This section is deliberately redundant for those that don't
646 want to read the whole thing (which is getting lengthy).
649 Ad blocking is but one of <application>Privoxy's</application>
650 array of features. Many of these features are for the technically minded advanced
651 user. But, ad and banner blocking is surely common ground for everybody.
654 This section will provide a quick summary of ad blocking so
655 you can get up to speed quickly without having to read the more extensive
656 information provided below, though this is highly recommended.
659 First a bit of a warning ... blocking ads is much like blocking SPAM: the
660 more aggressive you are about it, the more likely you are to block
661 things that were not intended. And the more likely that some things
662 may not work as intended. So there is a trade off here. If you want
663 extreme ad free browsing, be prepared to deal with more
664 <quote>problem</quote> sites, and to spend more time adjusting the
665 configuration to solve these unintended consequences. In short, there is
666 not an easy way to eliminate <emphasis>all</emphasis> ads. Either take
667 the easy way and settle for <emphasis>most</emphasis> ads blocked with the
668 default configuration, or jump in and tweak it for your personal surfing
669 habits and preferences.
672 Secondly, a brief explanation of <application>Privoxy's </application>
673 <quote>actions</quote>. <quote>Actions</quote> in this context, are
674 the directives we use to tell <application>Privoxy</application> to perform
675 some task relating to HTTP transactions (i.e. web browsing). We tell
676 <application>Privoxy</application> to take some <quote>action</quote>. Each
677 action has a unique name and function. While there are many potential
678 <application>actions</application> in <application>Privoxy's</application>
679 arsenal, only a few are used for ad blocking. <link
680 linkend="actions">Actions</link>, and <link linkend="actions-file">action
681 configuration files</link>, are explained in depth below.
684 Actions are specified in <application>Privoxy's</application> configuration,
685 followed by one or more URLs to which the action should apply. URLs
686 can actually be URL type <link linkend="af-patterns">patterns</link> that use
687 wildcards so they can apply potentially to a range of similar URLs. The
688 actions, together with the URL patterns are called a section.
691 When you connect to a website, the full URL will either match one or more
692 of the sections as defined in <application>Privoxy's</application> configuration,
693 or not. If so, then <application>Privoxy</application> will perform the
694 respective actions. If not, then nothing special happens. Furthermore, web
695 pages may contain embedded, secondary URLs that your web browser will
696 use to load additional components of the page, as it parses the
697 original page's HTML content. An ad image for instance, is just an URL
698 embedded in the page somewhere. The image itself may be on the same server,
699 or a server somewhere else on the Internet. Complex web pages will have many
700 such embedded URLs. &my-app; can deal with each URL individually, so, for
701 instance, the main page text is not touched, but images from such-and-such
706 The most important actions for basic ad blocking are: <literal><link
707 linkend="block">block</link></literal>, <literal><link
708 linkend="handle-as-image">handle-as-image</link></literal>,
710 linkend="handle-as-empty-document">handle-as-empty-document</link></literal>,and
711 <literal><link linkend="set-image-blocker">set-image-blocker</link></literal>:
719 <literal><link linkend="block">block</link></literal> - this is perhaps
720 the single most used action, and is particularly important for ad blocking.
721 This action stops any contact between your browser and any URL patterns
722 that match this action's configuration. It can be used for blocking ads,
723 but also anything that is determined to be unwanted. By itself, it simply
724 stops any communication with the remote server and sends
725 <application>Privoxy</application>'s own built-in BLOCKED page instead to
726 let you now what has happened (with some exceptions, see below).
732 <literal><link linkend="handle-as-image">handle-as-image</link></literal> -
733 tells <application>Privoxy</application> to treat this URL as an image.
734 <application>Privoxy</application>'s default configuration already does this
735 for all common image types (e.g. GIF), but there are many situations where this
736 is not so easy to determine. So we'll force it in these cases. This is particularly
737 important for ad blocking, since only if we know that it's an image of
738 some kind, can we replace it with an image of our choosing, instead of the
739 <application>Privoxy</application> BLOCKED page (which would only result in
740 a <quote>broken image</quote> icon). There are some limitations to this
741 though. For instance, you can't just brute-force an image substitution for
742 an entire HTML page in most situations.
748 <literal><link linkend="handle-as-empty-document">handle-as-empty-document</link></literal> -
749 sends an empty document instead of <application>Privoxy's</application>
750 normal BLOCKED HTML page. This is useful for file types that are neither
751 HTML nor images, such as blocking JavaScript files.
758 linkend="set-image-blocker">set-image-blocker</link></literal> - tells
759 <application>Privoxy</application> what to display in place of an ad image that
760 has hit a block rule. For this to come into play, the URL must match a
761 <literal><link linkend="block">block</link></literal> action somewhere in the
762 configuration, <emphasis>and</emphasis>, it must also match an
763 <literal><link linkend="handle-as-image">handle-as-image</link></literal> action.
766 The configuration options on what to display instead of the ad are:
770 <emphasis>pattern</emphasis> - a checkerboard pattern, so that an ad
771 replacement is obvious. This is the default.
776 <emphasis>blank</emphasis> - A very small empty GIF image is displayed.
777 This is the so-called <quote>invisible</quote> configuration option.
782 <emphasis>http://<URL></emphasis> - A redirect to any image anywhere
783 of the user's choosing (advanced usage).
792 Advanced users will eventually want to explore &my-app;
793 <literal><link linkend="filter">filters</link></literal> as well. Filters
794 are very different from <literal><link
795 linkend="block">blocks</link></literal>.
796 A <quote>block</quote> blocks a site, page, or unwanted contented. Filters
797 are a way of filtering or modifying what is actually on the page. An example
798 filter usage: a text replacement of <quote>no-no</quote> for
799 <quote>nasty-word</quote>. That is a very simple example. This process can be
800 used for ad blocking, but it is more in the realm of advanced usage and has
801 some pitfalls to be wary off.
805 The quickest way to adjust any of these settings is with your browser through
806 the special <application>Privoxy</application> editor at <ulink
807 url="http://config.privoxy.org/show-status">http://config.privoxy.org/show-status</ulink>
808 (shortcut: <ulink url="http://p.p/">http://p.p/show-status</ulink>). This
809 is an internal page, and does not require Internet access.
813 Note that as of <application>Privoxy</application> 3.0.7 beta the
814 action editor is disabled by default. Check the
815 <ulink url="config.html#ENABLE-EDIT-ACTIONS">enable-edit-actions
816 section in the configuration file</ulink> to learn why and in which
817 cases it's safe to enable again.
821 If you decided to enable the action editor, select the appropriate
822 <quote>actions</quote> file, and click
823 <quote><guibutton>Edit</guibutton></quote>. It is best to put personal or
824 local preferences in <filename>user.action</filename> since this is not
825 meant to be overwritten during upgrades, and will over-ride the settings in
826 other files. Here you can insert new <quote>actions</quote>, and URLs for ad
827 blocking or other purposes, and make other adjustments to the configuration.
828 <application>Privoxy</application> will detect these changes automatically.
832 A quick and simple step by step example:
840 Right click on the ad image to be blocked, then select
841 <quote><guimenuitem>Copy Link Location</guimenuitem></quote> from the
849 url="http://config.privoxy.org/show-status">http://config.privoxy.org/show-status</ulink>
854 Find <filename>user.action</filename> in the top section, and click
855 on <quote><guibutton>Edit</guibutton></quote>:
858 <!-- image of editor and actions files selections -->
860 <figure pgwide="0" float="0"><title>Actions Files in Use</title>
863 <imagedata fileref="files-in-use.jpg" format="jpg">
866 <phrase>[ Screenshot of Actions Files in Use ]</phrase>
875 You should have a section with only
876 <literal><link linkend="block">block</link></literal> listed under
877 <quote>Actions:</quote>.
878 If not, click a <quote><guibutton>Insert new section below</guibutton></quote>
879 button, and in the new section that just appeared, click the
880 <guibutton>Edit</guibutton> button right under the word <quote>Actions:</quote>.
881 This will bring up a list of all actions. Find
882 <literal><link linkend="block">block</link></literal> near the top, and click
883 in the <quote>Enabled</quote> column, then <quote><guibutton>Submit</guibutton></quote>
889 Now, in the <literal><link linkend="block">block</link></literal> actions section,
890 click the <quote><guibutton>Add</guibutton></quote> button, and paste the URL the
891 browser got from <quote><guimenuitem>Copy Link Location</guimenuitem></quote>.
892 Remove the <literal>http://</literal> at the beginning of the URL. Then, click
893 <quote><guibutton>Submit</guibutton></quote> (or
894 <quote><guibutton>OK</guibutton></quote> if in a pop-up window).
899 Now go back to the original page, and press <keycap>SHIFT-Reload</keycap>
900 (or flush all browser caches). The image should be gone now.
908 This is a very crude and simple example. There might be good reasons to use a
909 wildcard pattern match to include potentially similar images from the same
910 site. For a more extensive explanation of <quote>patterns</quote>, and
911 the entire actions concept, see <link linkend="actions-file">the Actions
916 For advanced users who want to hand edit their config files, you might want
917 to now go to the <link linkend="act-examples">Actions Files Tutorial</link>.
918 The ideas explained therein also apply to the web-based editor.
921 There are also various
922 <link linkend="filter">filters</link> that can be used for ad blocking
923 (filters are a special subset of actions). These
924 fall into the <quote>advanced</quote> usage category, and are explained in
925 depth in later sections.
932 <!-- ~ End section ~ -->
935 <!-- ~~~~~ New section ~~~~~ -->
937 <title>Starting Privoxy</title>
939 Before launching <application>Privoxy</application> for the first time, you
940 will want to configure your browser(s) to use
941 <application>Privoxy</application> as a HTTP and HTTPS (SSL)
942 <ulink url="http://en.wikipedia.org/wiki/Proxy_server">proxy</ulink>. The default is
943 127.0.0.1 (or localhost) for the proxy address, and port 8118 (earlier versions
944 used port 8000). This is the one configuration step <emphasis>that must be done
948 Please note that <application>Privoxy</application> can only proxy HTTP and
949 HTTPS traffic. It will not work with FTP or other protocols.
952 <!-- image of Mozilla Proxy configuration -->
954 <figure pgwide="0" float="0"><title>Proxy Configuration Showing
955 Mozilla/Netscape HTTP and HTTPS (SSL) Settings</title>
958 <imagedata fileref="proxy_setup.jpg" format="jpg">
961 <phrase>[ Screenshot of Mozilla Proxy Configuration ]</phrase>
969 With <application>Firefox</application>, this is typically set under:
973 <guibutton>Tools</guibutton> -> <guibutton>Options</guibutton> -> <guibutton>Advanced</guibutton> -> <guibutton>Network</guibutton> -><guibutton>Connection</guibutton> -> <guibutton>Settings</guibutton>
978 Or optionally on some platforms:
982 <guibutton>Edit</guibutton> -> <guibutton>Preferences</guibutton> -> <guibutton>General</guibutton> -> <guibutton>Connection Settings</guibutton> -> <guibutton>Manual Proxy Configuration</guibutton>
988 With <application>Netscape</application> (and
989 <application>Mozilla</application>), this can be set under:
994 <!-- Mix ascii and gui art, something for everybody -->
995 <!-- spacing on this is tricky -->
996 <guibutton>Edit</guibutton> -> <guibutton>Preferences</guibutton> -> <guibutton>Advanced</guibutton> -> <guibutton>Proxies</guibutton> -> <guibutton>HTTP Proxy</guibutton>
1001 For <application>Internet Explorer v.5-7</application>:
1005 <guibutton>Tools</guibutton> -> <guibutton>Internet Options</guibutton> -> <guibutton>Connections</guibutton> -> <guibutton>LAN Settings</guibutton>
1009 Then, check <quote>Use Proxy</quote> and fill in the appropriate info
1010 (Address: 127.0.0.1, Port: 8118). Include HTTPS (SSL), if you want HTTPS
1011 proxy support too (sometimes labeled <quote>Secure</quote>). Make sure any
1012 checkboxes like <quote>Use the same proxy server for all protocols</quote> is
1013 <emphasis>UNCHECKED</emphasis>. You want only HTTP and HTTPS (SSL)!
1016 <!-- image of IE Proxy configuration -->
1018 <figure pgwide="0" float="0"><title>Proxy Configuration Showing
1019 Internet Explorer HTTP and HTTPS (Secure) Settings</title>
1022 <imagedata fileref="proxy2.jpg" format="jpg">
1025 <phrase>[ Screenshot of IE Proxy Configuration ]</phrase>
1033 After doing this, flush your browser's disk and memory caches to force a
1034 re-reading of all pages and to get rid of any ads that may be cached. Remove
1035 any <ulink url="http://en.wikipedia.org/wiki/Browser_cookie">cookies</ulink>,
1036 if you want <application>Privoxy</application> to manage that. You are now
1037 ready to start enjoying the benefits of using
1038 <application>Privoxy</application>!
1042 <application>Privoxy</application> itself is typically started by specifying the
1043 main configuration file to be used on the command line. If no configuration
1044 file is specified on the command line, <application>Privoxy</application>
1045 will look for a file named <filename>config</filename> in the current
1046 directory. Except on Win32 where it will try <filename>config.txt</filename>.
1049 <sect2 id="start-debian">
1050 <title>Debian</title>
1052 We use a script. Note that Debian typically starts &my-app; upon booting per
1053 default. It will use the file
1054 <filename>/etc/privoxy/config</filename> as its main configuration
1059 # /etc/init.d/privoxy start
1064 <sect2 id="start-freebsd">
1065 <title>FreeBSD and ElectroBSD</title>
1067 To start <application>Privoxy</application> upon booting, add
1068 "privoxy_enable='YES'" to <filename>/etc/rc.conf</filename>.
1069 <application>Privoxy</application> will use
1070 <filename>/usr/local/etc/privoxy/config</filename> as its main
1074 If you installed <application>Privoxy</application> into a jail, the
1075 paths above are relative to the jail root.
1078 To start <application>Privoxy</application> manually, run:
1082 # service privoxy onestart
1087 <sect2 id="start-windows">
1088 <title>Windows</title>
1090 Click on the &my-app; Icon to start <application>Privoxy</application>. If no configuration file is
1091 specified on the command line, <application>Privoxy</application> will look
1092 for a file named <filename>config.txt</filename>. Note that Windows will
1093 automatically start &my-app; when the system starts if you chose that option
1097 <application>Privoxy</application> can run with full Windows service functionality.
1098 On Windows only, the &my-app; program has two new command line arguments
1099 to install and uninstall &my-app; as a service. See the
1100 <link linkend="installation-pack-win">Windows Installation
1101 instructions</link> for details.
1105 <sect2 id="start-unices">
1106 <title>Generic instructions for Unix derivates (Solaris, NetBSD, HP-UX etc.)</title>
1108 Example Unix startup command:
1112 # /usr/sbin/privoxy --user privoxy /etc/privoxy/config
1116 Note that if you installed <application>Privoxy</application> through
1117 a package manager, the package will probably contain a platform-specific
1118 script or configuration file to start <application>Privoxy</application>
1123 <sect2 id="start-os2">
1126 During installation, <application>Privoxy</application> is configured to
1127 start automatically when the system restarts. You can start it manually by
1128 double-clicking on the <application>Privoxy</application> icon in the
1129 <application>Privoxy</application> folder.
1133 <sect2 id="start-macosx">
1134 <title>Mac OS X</title>
1136 The privoxy service will automatically start after a successful installation
1137 (and thereafter every time your computer starts up) however you will need to
1138 configure your web browser(s) to use it. To do so, configure them to use a
1139 proxy for HTTP and HTTPS at the address 127.0.0.1:8118.
1142 To prevent the privoxy service from automatically starting when your computer
1143 starts up, remove or rename the file <literal>/Library/LaunchDaemons/org.ijbswa.privoxy.plist</literal>
1144 (on OS X 10.5 and higher) or the folder named
1145 <literal>/Library/StartupItems/Privoxy</literal> (on OS X 10.4 'Tiger').
1148 To manually start or stop the privoxy service, use the scripts startPrivoxy.sh
1149 and stopPrivoxy.sh supplied in /Applications/Privoxy. They must be run from an
1150 administrator account, using sudo.
1158 See the section <link linkend="cmdoptions">Command line options</link> for
1162 must find a better place for this paragraph
1165 The included default configuration files should give a reasonable starting
1166 point. Most of the per site configuration is done in the
1167 <ulink url="actions-file.html"><quote>actions</quote></ulink> files. These are
1168 where various cookie actions are defined, ad and banner blocking, and other
1169 aspects of <application>Privoxy</application> configuration. There are several
1170 such files included, with varying levels of aggressiveness.
1174 You will probably want to keep an eye out for sites for which you may prefer
1175 persistent cookies, and add these to your actions configuration as needed. By
1176 default, most of these will be accepted only during the current browser
1177 session (aka <quote>session cookies</quote>), unless you add them to the
1178 configuration. If you want the browser to handle this instead, you will need
1179 to edit <filename>user.action</filename> (or through the web based interface)
1180 and disable this feature. If you use more than one browser, it would make
1181 more sense to let <application>Privoxy</application> handle this. In which
1182 case, the browser(s) should be set to accept all cookies.
1186 Another feature where you will probably want to define exceptions for trusted
1187 sites is the popup-killing (through <ulink
1188 url="actions-file.html#FILTER-POPUPS"><quote>+filter{popups}</quote></ulink>),
1189 because your favorite shopping, banking, or leisure site may need
1190 popups (explained below).
1194 <application>Privoxy</application> does not support all of the optional HTTP/1.1
1195 features yet. In the unlikely event that you experience inexplicable problems
1196 with browsers that use HTTP/1.1 per default
1197 (like <application>Mozilla</application> or recent versions of I.E.), you might
1198 try to force HTTP/1.0 compatibility. For Mozilla, look under <literal>Edit ->
1199 Preferences -> Debug -> Networking</literal>.
1200 Alternatively, set the <quote>+downgrade-http-version</quote> config option in
1201 <filename>default.action</filename> which will downgrade your browser's HTTP
1202 requests from HTTP/1.1 to HTTP/1.0 before processing them.
1206 After running <application>Privoxy</application> for a while, you can
1207 start to fine tune the configuration to suit your personal, or site,
1208 preferences and requirements. There are many, many aspects that can
1209 be customized. <quote>Actions</quote>
1210 can be adjusted by pointing your browser to
1211 <ulink url="http://config.privoxy.org/">http://config.privoxy.org/</ulink>
1212 (shortcut: <ulink url="http://p.p/">http://p.p/</ulink>),
1213 and then follow the link to <quote>View & Change the Current Configuration</quote>.
1214 (This is an internal page and does not require Internet access.)
1218 In fact, various aspects of <application>Privoxy</application>
1219 configuration can be viewed from this page, including
1220 current configuration parameters, source code version numbers,
1221 the browser's request headers, and <quote>actions</quote> that apply
1222 to a given URL. In addition to the actions file
1223 editor mentioned above, <application>Privoxy</application> can also
1224 be turned <quote>on</quote> and <quote>off</quote> (toggled) from this page.
1228 If you encounter problems, try loading the page without
1229 <application>Privoxy</application>. If that helps, enter the URL where
1230 you have the problems into <ulink url="http://p.p/show-url-info">the browser
1231 based rule tracing utility</ulink>. See which rules apply and why, and
1232 then try turning them off for that site one after the other, until the problem
1233 is gone. When you have found the culprit, you might want to turn the rest on
1238 If the above paragraph sounds gibberish to you, you might want to <link
1239 linkend="actions-file">read more about the actions concept</link>
1240 or even dive deep into the <link linkend="actionsanat">Appendix
1245 If you can't get rid of the problem at all, think you've found a bug in
1246 Privoxy, want to propose a new feature or smarter rules, please see the
1247 section <link linkend="contact"><quote>Contacting the
1248 Developers</quote></link> below.
1253 <!-- ~~~~~ New section ~~~~~ -->
1254 <sect2 id="cmdoptions">
1255 <title>Command Line Options</title>
1257 <application>Privoxy</application> may be invoked with the following
1258 command-line options:
1266 <emphasis>--config-test</emphasis>
1269 Exit after loading the configuration files before binding to
1270 the listen address. The exit code signals whether or not the
1271 configuration files have been successfully loaded.
1274 If the exit code is 1, at least one of the configuration files
1275 is invalid, if it is 0, all the configuration files have been
1276 successfully loaded (but may still contain errors that can
1277 currently only be detected at run time).
1280 This option doesn't affect the log setting, combination with
1281 <emphasis>--no-daemon</emphasis> is recommended if a configured
1282 log file shouldn't be used.
1287 <emphasis>--version</emphasis>
1290 Print version info and exit. Unix only.
1295 <emphasis>--help</emphasis>
1298 Print short usage info and exit. Unix only.
1303 <emphasis>--no-daemon</emphasis>
1306 Don't become a daemon, i.e. don't fork and become process group
1307 leader, and don't detach from controlling tty. Unix only.
1312 <emphasis>--pidfile FILE</emphasis>
1315 On startup, write the process ID to <emphasis>FILE</emphasis>. Delete the
1316 <emphasis>FILE</emphasis> on exit. Failure to create or delete the
1317 <emphasis>FILE</emphasis> is non-fatal. If no <emphasis>FILE</emphasis>
1318 option is given, no PID file will be used. Unix only.
1323 <emphasis>--user USER[.GROUP]</emphasis>
1326 After (optionally) writing the PID file, assume the user ID of
1327 <emphasis>USER</emphasis>, and if included the GID of GROUP. Exit if the
1328 privileges are not sufficient to do so. Unix only.
1333 <emphasis>--chroot</emphasis>
1336 Before changing to the user ID given in the <emphasis>--user</emphasis> option,
1337 chroot to that user's home directory, i.e. make the kernel pretend to the &my-app;
1338 process that the directory tree starts there. If set up carefully, this can limit
1339 the impact of possible vulnerabilities in &my-app; to the files contained in that hierarchy.
1345 <emphasis>--pre-chroot-nslookup hostname</emphasis>
1348 Specifies a hostname (for example www.privoxy.org) to look up before doing a chroot.
1349 On some systems, initializing the resolver library involves reading config files from
1350 /etc and/or loading additional shared libraries from /lib.
1351 On these systems, doing a hostname lookup before the chroot reduces
1352 the number of files that must be copied into the chroot tree.
1355 For fastest startup speed, a good value is a hostname that is not in /etc/hosts but that
1356 your local name server (listed in /etc/resolv.conf) can resolve without recursion
1357 (that is, without having to ask any other name servers). The hostname need not exist,
1358 but if it doesn't, an error message (which can be ignored) will be output.
1364 <emphasis>configfile</emphasis>
1367 If no <emphasis>configfile</emphasis> is included on the command line,
1368 <application>Privoxy</application> will look for a file named
1369 <quote>config</quote> in the current directory (except on Win32
1370 where it will look for <quote>config.txt</quote> instead). Specify
1371 full path to avoid confusion. If no config file is found,
1372 <application>Privoxy</application> will fail to start.
1380 On <application>MS Windows</application> only there are two additional
1381 command-line options to allow <application>Privoxy</application> to install and
1382 run as a <emphasis>service</emphasis>. See the
1383 <link linkend="installation-pack-win">Window Installation section</link>
1391 <!-- ~ End section ~ -->
1394 <!-- ~~~~~ New section ~~~~~ -->
1395 <sect1 id="configuration"><title>Privoxy Configuration</title>
1397 All <application>Privoxy</application> configuration is stored
1398 in text files. These files can be edited with a text editor.
1399 Many important aspects of <application>Privoxy</application> can
1400 also be controlled easily with a web browser.
1404 <!-- ~~~~~ New section ~~~~~ -->
1406 <sect2 id="control-with-webbrowser">
1407 <title>Controlling Privoxy with Your Web Browser</title>
1409 <application>Privoxy</application>'s user interface can be reached through the special
1410 URL <ulink url="http://config.privoxy.org/">http://config.privoxy.org/</ulink>
1411 (shortcut: <ulink url="http://p.p/">http://p.p/</ulink>),
1412 which is a built-in page and works without Internet access.
1413 You will see the following section:
1417 <!-- Needs to be put in a table and colorized -->
1420 <bridgehead renderas="sect2"> Privoxy Menu</bridgehead>
1424 ▪ <ulink url="http://config.privoxy.org/show-status">View & change the current configuration</ulink>
1427 ▪ <ulink url="http://config.privoxy.org/show-version">View the source code version numbers</ulink>
1430 ▪ <ulink url="http://config.privoxy.org/show-request">View the request headers.</ulink>
1433 ▪ <ulink url="http://config.privoxy.org/show-url-info">Look up which actions apply to a URL and why</ulink>
1436 ▪ <ulink url="http://config.privoxy.org/toggle">Toggle Privoxy on or off</ulink>
1439 ▪ <ulink
1440 url="https://www.privoxy.org/&p-version;/user-manual/">Documentation</ulink>
1448 This should be self-explanatory. Note the first item leads to an editor for the
1449 <link linkend="actions-file">actions files</link>, which is where the ad, banner,
1450 cookie, and URL blocking magic is configured as well as other advanced features of
1451 <application>Privoxy</application>. This is an easy way to adjust various
1452 aspects of <application>Privoxy</application> configuration. The actions
1453 file, and other configuration files, are explained in detail below.
1457 <quote>Toggle Privoxy On or Off</quote> is handy for sites that might
1458 have problems with your current actions and filters. You can in fact use
1459 it as a test to see whether it is <application>Privoxy</application>
1460 causing the problem or not. <application>Privoxy</application> continues
1461 to run as a proxy in this case, but all manipulation is disabled, i.e.
1462 <application>Privoxy</application> acts like a normal forwarding proxy.
1466 Note that several of the features described above are disabled by default
1467 in <application>Privoxy</application> 3.0.7 beta and later.
1469 <ulink url="config.html">configuration file</ulink> to learn why
1470 and in which cases it's safe to enable them again.
1475 <!-- ~ End section ~ -->
1480 <!-- ~~~~~ New section ~~~~~ -->
1482 <sect2 id="confoverview">
1483 <title>Configuration Files Overview</title>
1485 For Unix, *BSD and Linux, all configuration files are located in
1486 <filename>/etc/privoxy/</filename> by default. For MS Windows, OS/2, and
1487 AmigaOS these are all in the same directory as the
1488 <application>Privoxy</application> executable. <![%p-not-stable;[ The name
1489 and number of configuration files has changed from previous versions, and is
1490 subject to change as development progresses.]]>
1494 The installed defaults provide a reasonable starting point, though
1495 some settings may be aggressive by some standards. For the time being, the
1496 principle configuration files are:
1504 The <link linkend="config">main configuration file</link> is named <filename>config</filename>
1505 on Linux, Unix, BSD, OS/2, and AmigaOS and <filename>config.txt</filename>
1506 on Windows. This is a required file.
1512 <filename>match-all.action</filename> is used to define which <quote>actions</quote>
1513 relating to banner-blocking, images, pop-ups, content modification, cookie handling
1514 etc should be applied by default. It should be the first actions file loaded.
1517 <filename>default.action</filename> defines many exceptions (both positive and negative)
1518 from the default set of actions that's configured in <filename>match-all.action</filename>.
1519 It should be the second actions file loaded and shouldn't be edited by the user.
1522 Multiple actions files may be defined in <filename>config</filename>. These
1523 are processed in the order they are defined. Local customizations and locally
1524 preferred exceptions to the default policies as defined in
1525 <filename>match-all.action</filename> (which you will most probably want
1526 to define sooner or later) are best applied in <filename>user.action</filename>,
1527 where you can preserve them across upgrades. The file isn't installed by all
1528 installers, but you can easily create it yourself with a text editor.
1531 There is also a web based editor that can be accessed from
1533 url="http://config.privoxy.org/show-status">http://config.privoxy.org/show-status</ulink>
1535 url="http://p.p/show-status">http://p.p/show-status</ulink>) for the
1536 various actions files.
1542 <quote>Filter files</quote> (the <link linkend="filter-file">filter
1543 file</link>) can be used to re-write the raw page content, including
1544 viewable text as well as embedded HTML and JavaScript, and whatever else
1545 lurks on any given web page. The filtering jobs are only pre-defined here;
1546 whether to apply them or not is up to the actions files.
1547 <filename>default.filter</filename> includes various filters made
1548 available for use by the developers. Some are much more intrusive than
1549 others, and all should be used with caution. You may define additional
1550 filter files in <filename>config</filename> as you can with
1551 actions files. We suggest <filename>user.filter</filename> for any
1552 locally defined filters or customizations.
1560 The syntax of the configuration and filter files may change between different
1561 Privoxy versions, unfortunately some enhancements cost backwards compatibility.
1562 <!-- Add link to documentation-->
1566 All files use the <quote><literal>#</literal></quote> character to denote a
1567 comment (the rest of the line will be ignored) and understand line continuation
1568 through placing a backslash ("<literal>\</literal>") as the very last character
1569 in a line. If the <literal>#</literal> is preceded by a backslash, it looses
1570 its special function. Placing a <literal>#</literal> in front of an otherwise
1571 valid configuration line to prevent it from being interpreted is called "commenting
1572 out" that line. Blank lines are ignored.
1576 The actions files and filter files
1577 can use Perl style <link linkend="regex">regular expressions</link> for
1578 maximum flexibility.
1582 After making any changes, there is no need to restart
1583 <application>Privoxy</application> in order for the changes to take
1584 effect. <application>Privoxy</application> detects such changes
1585 automatically. Note, however, that it may take one or two additional
1586 requests for the change to take effect. When changing the listening address
1587 of <application>Privoxy</application>, these <quote>wake up</quote> requests
1588 must obviously be sent to the <emphasis>old</emphasis> listening address.
1593 While under development, the configuration content is subject to change.
1594 The below documentation may not be accurate by the time you read this.
1595 Also, what constitutes a <quote>default</quote> setting, may change, so
1596 please check all your configuration files on important issues.
1602 <!-- ~ End section ~ -->
1605 <!-- ~~~~~~~~ New section Header ~~~~~~~~~ -->
1607 <!-- **************************************************** -->
1608 <!-- Include config.sgml here -->
1609 <!-- This is where the entire config file is detailed. -->
1611 <!-- end include -->
1614 <!-- ~ End section ~ -->
1618 <!-- ~~~~~~~~ New section Header ~~~~~~~~~ -->
1620 <sect1 id="actions-file"><title>Actions Files</title>
1624 XXX: similar descriptions are in the Configuration Files sections.
1625 We should only describe them at one place.
1628 The actions files are used to define what <emphasis>actions</emphasis>
1629 <application>Privoxy</application> takes for which URLs, and thus determines
1630 how ad images, cookies and various other aspects of HTTP content and
1631 transactions are handled, and on which sites (or even parts thereof).
1632 There are a number of such actions, with a wide range of functionality.
1633 Each action does something a little different.
1634 These actions give us a veritable arsenal of tools with which to exert
1635 our control, preferences and independence. Actions can be combined so that
1636 their effects are aggregated when applied against a given set of URLs.
1640 are three action files included with <application>Privoxy</application> with
1647 <filename>match-all.action</filename> - is used to define which
1648 <quote>actions</quote> relating to banner-blocking, images, pop-ups,
1649 content modification, cookie handling etc should be applied by default.
1650 It should be the first actions file loaded
1655 <filename>default.action</filename> - defines many exceptions (both
1656 positive and negative) from the default set of actions that's configured
1657 in <filename>match-all.action</filename>. It is a set of rules that should
1658 work reasonably well as-is for most users. This file is only supposed to
1659 be edited by the developers. It should be the second actions file loaded.
1664 <filename>user.action</filename> - is intended to be for local site
1665 preferences and exceptions. As an example, if your ISP or your bank
1666 has specific requirements, and need special handling, this kind of
1667 thing should go here. This file will not be upgraded.
1672 <guibutton>Edit</guibutton> <guibutton>Set to Cautious</guibutton> <guibutton>Set to Medium</guibutton> <guibutton>Set to Advanced</guibutton>
1675 These have increasing levels of aggressiveness <emphasis>and have no
1676 influence on your browsing unless you select them explicitly in the
1677 editor</emphasis>. A default installation should be pre-set to
1678 <literal>Cautious</literal>. New users should try this for a while before
1679 adjusting the settings to more aggressive levels. The more aggressive
1680 the settings, then the more likelihood there is of problems such as sites
1681 not working as they should.
1684 The <guibutton>Edit</guibutton> button allows you to turn each
1685 action on/off individually for fine-tuning. The <guibutton>Cautious</guibutton>
1686 button changes the actions list to low/safe settings which will activate
1687 ad blocking and a minimal set of &my-app;'s features, and subsequently
1688 there will be less of a chance for accidental problems. The
1689 <guibutton>Medium</guibutton> button sets the list to a medium level of
1690 other features and a low level set of privacy features. The
1691 <guibutton>Advanced</guibutton> button sets the list to a high level of
1692 ad blocking and medium level of privacy. See the chart below. The latter
1693 three buttons over-ride any changes via with the
1694 <guibutton>Edit</guibutton> button. More fine-tuning can be done in the
1695 lower sections of this internal page.
1698 While the actions file editor allows to enable these settings in all
1699 actions files, they are only supposed to be enabled in the first one
1700 to make sure you don't unintentionally overrule earlier rules.
1703 The default profiles, and their associated actions, as pre-defined in
1704 <filename>default.action</filename> are:
1707 <table frame=all><title>Default Configurations</title>
1708 <tgroup cols=4 align=left colsep=1 rowsep=1>
1709 <colspec colname=c1>
1710 <colspec colname=c2>
1711 <colspec colname=c3>
1712 <colspec colname=c4>
1715 <entry>Feature</entry>
1716 <entry>Cautious</entry>
1717 <entry>Medium</entry>
1718 <entry>Advanced</entry>
1723 <!-- <entry>f1</entry> -->
1724 <!-- <entry>f2</entry> -->
1725 <!-- <entry>f3</entry> -->
1726 <!-- <entry>f4</entry> -->
1732 <entry>Ad-blocking Aggressiveness</entry>
1733 <entry>medium</entry>
1739 <entry>Ad-filtering by size</entry>
1746 <entry>Ad-filtering by link</entry>
1752 <entry>Pop-up killing</entry>
1753 <entry>blocks only</entry>
1754 <entry>blocks only</entry>
1755 <entry>blocks only</entry>
1759 <entry>Privacy Features</entry>
1761 <entry>medium</entry>
1762 <entry>medium/high</entry>
1766 <entry>Cookie handling</entry>
1768 <entry>session-only</entry>
1773 <entry>Referer forging</entry>
1780 <entry>GIF de-animation</entry>
1787 <entry>Fast redirects</entry>
1794 <entry>HTML taming</entry>
1801 <entry>JavaScript taming</entry>
1808 <entry>Web-bug killing</entry>
1815 <entry>Image tag reordering</entry>
1831 The list of actions files to be used are defined in the main configuration
1832 file, and are processed in the order they are defined (e.g.
1833 <filename>default.action</filename> is typically processed before
1834 <filename>user.action</filename>). The content of these can all be viewed and
1836 url="http://config.privoxy.org/show-status">http://config.privoxy.org/show-status</ulink>.
1837 The over-riding principle when applying actions, is that the last action that
1838 matches a given URL wins. The broadest, most general rules go first
1839 (defined in <filename>default.action</filename>),
1840 followed by any exceptions (typically also in
1841 <filename>default.action</filename>), which are then followed lastly by any
1842 local preferences (typically in <emphasis>user</emphasis><filename>.action</filename>).
1843 Generally, <filename>user.action</filename> has the last word.
1847 An actions file typically has multiple sections. If you want to use
1848 <quote>aliases</quote> in an actions file, you have to place the (optional)
1849 <link linkend="aliases">alias section</link> at the top of that file.
1850 Then comes the default set of rules which will apply universally to all
1851 sites and pages (be <emphasis>very careful</emphasis> with using such a
1852 universal set in <filename>user.action</filename> or any other actions file after
1853 <filename>default.action</filename>, because it will override the result
1854 from consulting any previous file). And then below that,
1855 exceptions to the defined universal policies. You can regard
1856 <filename>user.action</filename> as an appendix to <filename>default.action</filename>,
1857 with the advantage that it is a separate file, which makes preserving your
1858 personal settings across <application>Privoxy</application> upgrades easier.
1862 Actions can be used to block anything you want, including ads, banners, or
1863 just some obnoxious URL whose content you would rather not see. Cookies can be accepted
1864 or rejected, or accepted only during the current browser session (i.e. not
1865 written to disk), content can be modified, some JavaScripts tamed, user-tracking
1866 fooled, and much more. See below for a <link linkend="actions">complete list
1870 <!-- ~~~~~ New section ~~~~~ -->
1871 <sect2 id="right-mix">
1872 <title>Finding the Right Mix</title>
1874 Note that some <link linkend="actions">actions</link>, like cookie suppression
1875 or script disabling, may render some sites unusable that rely on these
1876 techniques to work properly. Finding the right mix of actions is not always easy and
1877 certainly a matter of personal taste. And, things can always change, requiring
1878 refinements in the configuration. In general, it can be said that the more
1879 <quote>aggressive</quote> your default settings (in the top section of the
1880 actions file) are, the more exceptions for <quote>trusted</quote> sites you
1881 will have to make later. If, for example, you want to crunch all cookies per
1882 default, you'll have to make exceptions from that rule for sites that you
1883 regularly use and that require cookies for actually useful purposes, like maybe
1884 your bank, favorite shop, or newspaper.
1888 We have tried to provide you with reasonable rules to start from in the
1889 distribution actions files. But there is no general rule of thumb on these
1890 things. There just are too many variables, and sites are constantly changing.
1891 Sooner or later you will want to change the rules (and read this chapter again :).
1895 <!-- ~~~~~ New section ~~~~~ -->
1896 <sect2 id="how-to-edit">
1897 <title>How to Edit</title>
1899 The easiest way to edit the actions files is with a browser by
1900 using our browser-based editor, which can be reached from <ulink
1901 url="http://config.privoxy.org/show-status">http://config.privoxy.org/show-status</ulink>.
1902 Note: the config file option <link
1903 linkend="enable-edit-actions">enable-edit-actions</link> must be enabled for
1904 this to work. The editor allows both fine-grained control over every single
1905 feature on a per-URL basis, and easy choosing from wholesale sets of defaults
1906 like <quote>Cautious</quote>, <quote>Medium</quote> or
1907 <quote>Advanced</quote>. Warning: the <quote>Advanced</quote> setting is more
1908 aggressive, and will be more likely to cause problems for some sites.
1909 Experienced users only!
1913 If you prefer plain text editing to GUIs, you can of course also directly edit the
1914 the actions files with your favorite text editor. Look at
1915 <filename>default.action</filename> which is richly commented with many
1921 <sect2 id="actions-apply">
1922 <title>How Actions are Applied to Requests</title>
1924 Actions files are divided into sections. There are special sections,
1925 like the <quote><link linkend="aliases">alias</link></quote> sections which will
1926 be discussed later. For now let's concentrate on regular sections: They have a
1927 heading line (often split up to multiple lines for readability) which consist
1928 of a list of actions, separated by whitespace and enclosed in curly braces.
1929 Below that, there is a list of URL and tag patterns, each on a separate line.
1933 To determine which actions apply to a request, the URL of the request is
1934 compared to all URL patterns in each <quote>action file</quote>.
1935 Every time it matches, the list of applicable actions for the request is
1936 incrementally updated, using the heading of the section in which the
1937 pattern is located. The same is done again for tags and tag patterns later on.
1941 If multiple applying sections set the same action differently,
1942 the last match wins. If not, the effects are aggregated.
1943 E.g. a URL might match a regular section with a heading line of <literal>{
1944 +<link linkend="handle-as-image">handle-as-image</link> }</literal>,
1945 then later another one with just <literal>{
1946 +<link linkend="block">block</link> }</literal>, resulting
1947 in <emphasis>both</emphasis> actions to apply. And there may well be
1948 cases where you will want to combine actions together. Such a section then
1954 { +<literal>handle-as-image</literal> +<literal>block{Banner ads.}</literal> }
1955 # Block these as if they were images. Send no block page.
1957 media.example.com/.*banners
1958 .example.com/images/ads/</screen>
1962 You can trace this process for URL patterns and any given URL by visiting <ulink
1963 url="http://config.privoxy.org/show-url-info">http://config.privoxy.org/show-url-info</ulink>.
1967 Examples and more detail on this is provided in the Appendix, <link linkend="ACTIONSANAT">
1968 Troubleshooting: Anatomy of an Action</link> section.
1972 <!-- ~~~~~ New section ~~~~~ -->
1973 <sect2 id="af-patterns">
1974 <title>Patterns</title>
1976 As mentioned, <application>Privoxy</application> uses <quote>patterns</quote>
1977 to determine what <emphasis>actions</emphasis> might apply to which sites and
1978 pages your browser attempts to access. These <quote>patterns</quote> use wild
1979 card type <emphasis>pattern</emphasis> matching to achieve a high degree of
1980 flexibility. This allows one expression to be expanded and potentially match
1981 against many similar patterns.
1985 Generally, an URL pattern has the form
1986 <literal><host><port>/<path></literal>, where the
1987 <literal><host></literal>, the <literal><port></literal>
1988 and the <literal><path></literal> are optional. (This is why the special
1989 <literal>/</literal> pattern matches all URLs). Note that the protocol
1990 portion of the URL pattern (e.g. <literal>http://</literal>) should
1991 <emphasis>not</emphasis> be included in the pattern. This is assumed already!
1994 The pattern matching syntax is different for the host and path parts of
1995 the URL. The host part uses a simple globbing type matching technique,
1996 while the path part uses more flexible
1997 <ulink url="http://en.wikipedia.org/wiki/Regular_expressions"><quote>Regular
1998 Expressions</quote></ulink> (POSIX 1003.2).
2001 The port part of a pattern is a decimal port number preceded by a colon
2002 (<literal>:</literal>). If the host part contains a numerical IPv6 address,
2003 it has to be put into angle brackets
2004 (<literal><</literal>, <literal>></literal>).
2009 <term><literal>www.example.com/</literal></term>
2012 is a host-only pattern and will match any request to <literal>www.example.com</literal>,
2013 regardless of which document on that server is requested. So ALL pages in
2014 this domain would be covered by the scope of this action. Note that a
2015 simple <literal>example.com</literal> is different and would NOT match.
2020 <term><literal>www.example.com</literal></term>
2023 means exactly the same. For host-only patterns, the trailing <literal>/</literal> may
2029 <term><literal>www.example.com/index.html</literal></term>
2032 matches all the documents on <literal>www.example.com</literal>
2033 whose name starts with <literal>/index.html</literal>.
2038 <term><literal>www.example.com/index.html$</literal></term>
2041 matches only the single document <literal>/index.html</literal>
2042 on <literal>www.example.com</literal>.
2047 <term><literal>/index.html$</literal></term>
2050 matches the document <literal>/index.html</literal>, regardless of the domain,
2051 i.e. on <emphasis>any</emphasis> web server anywhere.
2056 <term><literal>/</literal></term>
2059 Matches any URL because there's no requirement for either the
2060 domain or the path to match anything.
2065 <term><literal>:8000/</literal></term>
2068 Matches any URL pointing to TCP port 8000.
2073 <term><literal>10.0.0.1/</literal></term>
2076 Matches any URL with the host address <literal>10.0.0.1</literal>.
2077 (Note that the real URL uses plain brackets, not angle brackets.)
2082 <term><literal><2001:db8::1>/</literal></term>
2085 Matches any URL with the host address <literal>2001:db8::1</literal>.
2086 (Note that the real URL uses plain brackets, not angle brackets.)
2091 <term><literal>index.html</literal></term>
2094 matches nothing, since it would be interpreted as a domain name and
2095 there is no top-level domain called <literal>.html</literal>. So its
2103 <!-- ~~~~~ New section ~~~~~ -->
2104 <sect3 id="host-pattern"><title>The Host Pattern</title>
2107 The matching of the host part offers some flexible options: if the
2108 host pattern starts or ends with a dot, it becomes unanchored at that end.
2109 The host pattern is often referred to as domain pattern as it is usually
2110 used to match domain names and not IP addresses.
2116 <term><literal>.example.com</literal></term>
2119 matches any domain with first-level domain <literal>com</literal>
2120 and second-level domain <literal>example</literal>.
2121 For example <literal>www.example.com</literal>,
2122 <literal>example.com</literal> and <literal>foo.bar.baz.example.com</literal>.
2123 Note that it wouldn't match if the second-level domain was <literal>another-example</literal>.
2128 <term><literal>www.</literal></term>
2131 matches any domain that <emphasis>STARTS</emphasis> with
2132 <literal>www.</literal> (It also matches the domain
2133 <literal>www</literal> but most of the time that doesn't matter.)
2138 <term><literal>.example.</literal></term>
2141 matches any domain that <emphasis>CONTAINS</emphasis> <literal>.example.</literal>.
2142 And, by the way, also included would be any files or documents that exist
2143 within that domain since no path limitations are specified. (Correctly
2144 speaking: It matches any FQDN that contains <literal>example</literal> as
2145 a domain.) This might be <literal>www.example.com</literal>,
2146 <literal>news.example.de</literal>, or
2147 <literal>www.example.net/cgi/testing.pl</literal> for instance. All these
2155 Additionally, there are wild-cards that you can use in the domain names
2156 themselves. These work similarly to shell globbing type wild-cards:
2157 <quote>*</quote> represents zero or more arbitrary characters (this is
2159 <ulink url="http://en.wikipedia.org/wiki/Regular_expressions"><quote>Regular
2160 Expression</quote></ulink> based syntax of <quote>.*</quote>),
2161 <quote>?</quote> represents any single character (this is equivalent to the
2162 regular expression syntax of a simple <quote>.</quote>), and you can define
2163 <quote>character classes</quote> in square brackets which is similar to
2164 the same regular expression technique. All of this can be freely mixed:
2169 <term><literal>ad*.example.com</literal></term>
2172 matches <quote>adserver.example.com</quote>,
2173 <quote>ads.example.com</quote>, etc but not <quote>sfads.example.com</quote>
2178 <term><literal>*ad*.example.com</literal></term>
2181 matches all of the above, and then some.
2186 <term><literal>.?pix.com</literal></term>
2189 matches <literal>www.ipix.com</literal>,
2190 <literal>pictures.epix.com</literal>, <literal>a.b.c.d.e.upix.com</literal> etc.
2195 <term><literal>www[1-9a-ez].example.c*</literal></term>
2198 matches <literal>www1.example.com</literal>,
2199 <literal>www4.example.cc</literal>, <literal>wwwd.example.cy</literal>,
2200 <literal>wwwz.example.com</literal> etc., but <emphasis>not</emphasis>
2201 <literal>wwww.example.com</literal>.
2208 While flexible, this is not the sophistication of full regular expression based syntax.
2213 <!-- ~ End section ~ -->
2216 <!-- ~~~~~ New section ~~~~~ -->
2217 <sect3 id="path-pattern"><title>The Path Pattern</title>
2220 <application>Privoxy</application> uses <quote>modern</quote> POSIX 1003.2
2221 <ulink url="http://en.wikipedia.org/wiki/Regular_expressions"><quote>Regular
2222 Expressions</quote></ulink> for matching the path portion (after the slash),
2223 and is thus more flexible.
2227 There is an <link linkend="regex">Appendix</link> with a brief quick-start into regular
2228 expressions, you also might want to have a look at your operating system's documentation
2229 on regular expressions (try <literal>man re_format</literal>).
2233 Note that the path pattern is automatically left-anchored at the <quote>/</quote>,
2234 i.e. it matches as if it would start with a <quote>^</quote> (regular expression speak
2235 for the beginning of a line).
2239 Please also note that matching in the path is <emphasis>CASE INSENSITIVE</emphasis>
2240 by default, but you can switch to case sensitive at any point in the pattern by using the
2241 <quote>(?-i)</quote> switch: <literal>www.example.com/(?-i)PaTtErN.*</literal> will match
2242 only documents whose path starts with <literal>PaTtErN</literal> in
2243 <emphasis>exactly</emphasis> this capitalization.
2248 <term><literal>.example.com/.*</literal></term>
2251 Is equivalent to just <quote>.example.com</quote>, since any documents
2252 within that domain are matched with or without the <quote>.*</quote>
2253 regular expression. This is redundant
2258 <term><literal>.example.com/.*/index.html$</literal></term>
2261 Will match any page in the domain of <quote>example.com</quote> that is
2262 named <quote>index.html</quote>, and that is part of some path. For
2263 example, it matches <quote>www.example.com/testing/index.html</quote> but
2264 NOT <quote>www.example.com/index.html</quote> because the regular
2265 expression called for at least two <quote>/'s</quote>, thus the path
2266 requirement. It also would match
2267 <quote>www.example.com/testing/index_html</quote>, because of the
2268 special meta-character <quote>.</quote>.
2273 <term><literal>.example.com/(.*/)?index\.html$</literal></term>
2276 This regular expression is conditional so it will match any page
2277 named <quote>index.html</quote> regardless of path which in this case can
2278 have one or more <quote>/'s</quote>. And this one must contain exactly
2279 <quote>.html</quote> (and end with that!).
2284 <term><literal>.example.com/(.*/)(ads|banners?|junk)</literal></term>
2287 This regular expression will match any path of <quote>example.com</quote>
2288 that contains any of the words <quote>ads</quote>, <quote>banner</quote>,
2289 <quote>banners</quote> (because of the <quote>?</quote>) or <quote>junk</quote>.
2290 The path does not have to end in these words, just contain them.
2291 The path has to contain at least two slashes (including the one at the beginning).
2296 <term><literal>.example.com/(.*/)(ads|banners?|junk)/.*\.(jpe?g|gif|png)$</literal></term>
2299 This is very much the same as above, except now it must end in either
2300 <quote>.jpg</quote>, <quote>.jpeg</quote>, <quote>.gif</quote> or <quote>.png</quote>. So this
2301 one is limited to common image formats.
2308 There are many, many good examples to be found in <filename>default.action</filename>,
2309 and more tutorials below in <link linkend="regex">Appendix on regular expressions</link>.
2314 <!-- ~ End section ~ -->
2317 <!-- ~~~~~ New section ~~~~~ -->
2318 <sect3 id="tag-pattern"><title>The Request Tag Pattern</title>
2321 Request tag patterns are used to change the applying actions based on the
2322 request's tags. Tags can be created based on HTTP headers with either
2323 the <link linkend="CLIENT-HEADER-TAGGER">client-header-tagger</link>
2324 or the <link linkend="SERVER-HEADER-TAGGER">server-header-tagger</link> action.
2328 Request tag patterns have to start with <quote>TAG:</quote>, so &my-app;
2329 can tell them apart from other patterns. Everything after the colon
2330 including white space, is interpreted as a regular expression with
2331 path pattern syntax, except that tag patterns aren't left-anchored
2332 automatically (&my-app; doesn't silently add a <quote>^</quote>,
2333 you have to do it yourself if you need it).
2337 To match all requests that are tagged with <quote>foo</quote>
2338 your pattern line should be <quote>TAG:^foo$</quote>,
2339 <quote>TAG:foo</quote> would work as well, but it would also
2340 match requests whose tags contain <quote>foo</quote> somewhere.
2341 <quote>TAG: foo</quote> wouldn't work as it requires white space.
2345 Sections can contain URL and request tag patterns at the same time,
2346 but request tag patterns are checked after the URL patterns and thus
2347 always overrule them, even if they are located before the URL patterns.
2351 Once a new request tag is added, Privoxy checks right away if it's matched by one
2352 of the request tag patterns and updates the action settings accordingly. As a result
2353 request tags can be used to activate other tagger actions, as long as these other
2354 taggers look for headers that haven't already be parsed.
2358 For example you could tag client requests which use the
2359 <literal>POST</literal> method,
2360 then use this tag to activate another tagger that adds a tag if cookies
2361 are sent, and then use a block action based on the cookie tag. This allows
2362 the outcome of one action, to be input into a subsequent action. However if
2363 you'd reverse the position of the described taggers, and activated the
2364 method tagger based on the cookie tagger, no method tags would be created.
2365 The method tagger would look for the request line, but at the time
2366 the cookie tag is created, the request line has already been parsed.
2370 While this is a limitation you should be aware of, this kind of
2371 indirection is seldom needed anyway and even the example doesn't
2372 make too much sense.
2377 <!-- ~~~~~ New section ~~~~~ -->
2378 <sect3 id="negative-tag-patterns"><title>The Negative Request Tag Patterns</title>
2381 To match requests that do not have a certain request tag, specify a negative tag pattern
2382 by prefixing the tag pattern line with either <quote>NO-REQUEST-TAG:</quote>
2383 or <quote>NO-RESPONSE-TAG:</quote> instead of <quote>TAG:</quote>.
2387 Negative request tag patterns created with <quote>NO-REQUEST-TAG:</quote> are checked
2388 after all client headers are scanned, the ones created with <quote>NO-RESPONSE-TAG:</quote>
2389 are checked after all server headers are scanned. In both cases all the created
2390 tags are considered.
2394 <!-- ~~~~~ New section ~~~~~ -->
2395 <sect3 id="client-tag-pattern"><title>The Client Tag Pattern</title>
2397 <!-- XXX: This section contains duplicates content from the
2398 client-specific-tag documentation. -->
2402 This is an experimental feature. The syntax is likely to change in future versions.
2407 Client tag patterns are not set based on HTTP headers but based on
2408 the client's IP address. Users can enable them themselves, but the
2409 Privoxy admin controls which tags are available and what their effect
2414 After a client-specific tag has been defined with the
2415 <link linkend="client-specific-tag">client-specific-tag</link>,
2416 directive, action sections can be activated based on the tag by using a
2417 CLIENT-TAG pattern. The CLIENT-TAG pattern is evaluated at the same priority
2418 as URL patterns, as a result the last matching pattern wins. Tags that
2419 are created based on client or server headers are evaluated later on
2420 and can overrule CLIENT-TAG and URL patterns!
2423 The tag is set for all requests that come from clients that requested
2424 it to be set. Note that "clients" are differentiated by IP address,
2425 if the IP address changes the tag has to be requested again.
2428 Clients can request tags to be set by using the CGI interface <ulink
2429 url="http://config.privoxy.org/client-tags">http://config.privoxy.org/client-tags</ulink>.
2438 # If the admin defined the client-specific-tag circumvent-blocks,
2439 # and the request comes from a client that previously requested
2440 # the tag to be set, overrule all previous +block actions that
2441 # are enabled based on URL to CLIENT-TAG patterns.
2443 CLIENT-TAG:^circumvent-blocks$
2445 # This section is not overruled because it's located after
2447 {+block{Nobody is supposed to request this.}}
2448 example.org/blocked-example-page</screen>
2455 <!-- ~ End section ~ -->
2458 <!-- ~~~~~ New section ~~~~~ -->
2460 <sect2 id="actions">
2461 <title>Actions</title>
2463 All actions are disabled by default, until they are explicitly enabled
2464 somewhere in an actions file. Actions are turned on if preceded with a
2465 <quote>+</quote>, and turned off if preceded with a <quote>-</quote>. So a
2466 <literal>+action</literal> means <quote>do that action</quote>, e.g.
2467 <literal>+block</literal> means <quote>please block URLs that match the
2468 following patterns</quote>, and <literal>-block</literal> means <quote>don't
2469 block URLs that match the following patterns, even if <literal>+block</literal>
2470 previously applied.</quote>
2475 Again, actions are invoked by placing them on a line, enclosed in curly braces and
2476 separated by whitespace, like in
2477 <literal>{+some-action -some-other-action{some-parameter}}</literal>,
2478 followed by a list of URL patterns, one per line, to which they apply.
2479 Together, the actions line and the following pattern lines make up a section
2480 of the actions file.
2484 Actions fall into three categories:
2491 Boolean, i.e the action can only be <quote>enabled</quote> or
2492 <quote>disabled</quote>. Syntax:
2496 +<replaceable class="function">name</replaceable> # enable action <replaceable class="parameter">name</replaceable>
2497 -<replaceable class="function">name</replaceable> # disable action <replaceable class="parameter">name</replaceable></screen>
2500 Example: <literal>+handle-as-image</literal>
2507 Parameterized, where some value is required in order to enable this type of action.
2512 +<replaceable class="function">name</replaceable>{<replaceable class="parameter">param</replaceable>} # enable action and set parameter to <replaceable class="parameter">param</replaceable>,
2513 # overwriting parameter from previous match if necessary
2514 -<replaceable class="function">name</replaceable> # disable action. The parameter can be omitted</screen>
2517 Note that if the URL matches multiple positive forms of a parameterized action,
2518 the last match wins, i.e. the params from earlier matches are simply ignored.
2521 Example: <literal>+hide-user-agent{Mozilla/5.0 (X11; U; FreeBSD i386; en-US; rv:1.8.1.4) Gecko/20070602 Firefox/2.0.0.4}</literal>
2527 Multi-value. These look exactly like parameterized actions,
2528 but they behave differently: If the action applies multiple times to the
2529 same URL, but with different parameters, <emphasis>all</emphasis> the parameters
2530 from <emphasis>all</emphasis> matches are remembered. This is used for actions
2531 that can be executed for the same request repeatedly, like adding multiple
2532 headers, or filtering through multiple filters. Syntax:
2536 +<replaceable class="function">name</replaceable>{<replaceable class="parameter">param</replaceable>} # enable action and add <replaceable class="parameter">param</replaceable> to the list of parameters
2537 -<replaceable class="function">name</replaceable>{<replaceable class="parameter">param</replaceable>} # remove the parameter <replaceable class="parameter">param</replaceable> from the list of parameters
2538 # If it was the last one left, disable the action.
2539 <replaceable class="parameter">-name</replaceable> # disable this action completely and remove all parameters from the list</screen>
2542 Examples: <literal>+add-header{X-Fun-Header: Some text}</literal> and
2543 <literal>+filter{html-annoyances}</literal>
2551 If nothing is specified in any actions file, no <quote>actions</quote> are
2552 taken. So in this case <application>Privoxy</application> would just be a
2553 normal, non-blocking, non-filtering proxy. You must specifically enable the
2554 privacy and blocking features you need (although the provided default actions
2555 files will give a good starting point).
2559 Later defined action sections always over-ride earlier ones of the same type.
2560 So exceptions to any rules you make, should come in the latter part of the file (or
2561 in a file that is processed later when using multiple actions files such
2562 as <filename>user.action</filename>). For multi-valued actions, the actions
2563 are applied in the order they are specified. Actions files are processed in
2564 the order they are defined in <filename>config</filename> (the default
2565 installation has three actions files). It also quite possible for any given
2566 URL to match more than one <quote>pattern</quote> (because of wildcards and
2567 regular expressions), and thus to trigger more than one set of actions! Last
2571 <!-- start actions listing -->
2573 The list of valid <application>Privoxy</application> actions are:
2577 <!-- ********************************************************** -->
2578 <!-- Please note the below defined actions use id's that are -->
2579 <!-- probably linked from other places, so please don't change. -->
2581 <!-- ********************************************************** -->
2584 <!-- ~~~~~ New section ~~~~~ -->
2586 <sect3 renderas="sect4" id="add-header">
2587 <title>add-header</title>
2591 <term>Typical use:</term>
2593 <para>Confuse log analysis, custom applications</para>
2598 <term>Effect:</term>
2601 Sends a user defined HTTP header to the web server.
2608 <!-- boolean, parameterized, Multi-value -->
2610 <para>Multi-value.</para>
2615 <term>Parameter:</term>
2618 Any string value is possible. Validity of the defined HTTP headers is not checked.
2619 It is recommended that you use the <quote><literal>X-</literal></quote> prefix
2629 This action may be specified multiple times, in order to define multiple
2630 headers. This is rarely needed for the typical user. If you don't know what
2631 <quote>HTTP headers</quote> are, you definitely don't need to worry about this
2635 Headers added by this action are not modified by other actions.
2641 <term>Example usage:</term>
2644 <screen># Add a DNT ("Do not track") header to all requests,
2645 # event to those that already have one.
2647 # This is just an example, not a recommendation.
2649 # There is no reason to believe that user-tracking websites care
2650 # about the DNT header and depending on the User-Agent, adding the
2651 # header may make user-tracking easier.
2652 {+add-header{DNT: 1}}
2661 <!-- ~~~~~ New section ~~~~~ -->
2662 <sect3 renderas="sect4" id="block">
2663 <title>block</title>
2667 <term>Typical use:</term>
2669 <para>Block ads or other unwanted content</para>
2674 <term>Effect:</term>
2677 Requests for URLs to which this action applies are blocked, i.e. the
2678 requests are trapped by &my-app; and the requested URL is never retrieved,
2679 but is answered locally with a substitute page or image, as determined by
2681 linkend="handle-as-image">handle-as-image</link></literal>,
2683 linkend="set-image-blocker">set-image-blocker</link></literal>, and
2685 linkend="handle-as-empty-document">handle-as-empty-document</link></literal> actions.
2693 <!-- boolean, parameterized, Multi-value -->
2695 <para>Parameterized.</para>
2700 <term>Parameter:</term>
2702 <para>A block reason that should be given to the user.</para>
2710 <application>Privoxy</application> sends a special <quote>BLOCKED</quote> page
2711 for requests to blocked pages. This page contains the block reason given as
2712 parameter, a link to find out why the block action applies, and a click-through
2713 to the blocked content (the latter only if the force feature is available and
2717 A very important exception occurs if <emphasis>both</emphasis>
2718 <literal>block</literal> and <literal><link linkend="handle-as-image">handle-as-image</link></literal>,
2719 apply to the same request: it will then be replaced by an image. If
2720 <literal><link linkend="set-image-blocker">set-image-blocker</link></literal>
2721 (see below) also applies, the type of image will be determined by its parameter,
2722 if not, the standard checkerboard pattern is sent.
2725 It is important to understand this process, in order
2726 to understand how <application>Privoxy</application> deals with
2727 ads and other unwanted content. Blocking is a core feature, and one
2728 upon which various other features depend.
2731 The <literal><link linkend="filter">filter</link></literal>
2732 action can perform a very similar task, by <quote>blocking</quote>
2733 banner images and other content through rewriting the relevant URLs in the
2734 document's HTML source, so they don't get requested in the first place.
2735 Note that this is a totally different technique, and it's easy to confuse the two.
2741 <term>Example usage (section):</term>
2744 <screen>{+block{No nasty stuff for you.}}
2745 # Block and replace with "blocked" page
2746 .nasty-stuff.example.com
2748 {+block{Doubleclick banners.} +handle-as-image}
2749 # Block and replace with image
2753 {+block{Layered ads.} +handle-as-empty-document}
2754 # Block and then ignore
2755 adserver.example.net/.*\.js$</screen>
2765 <!-- ~~~~~ New section ~~~~~ -->
2766 <sect3 renderas="sect4" id="change-x-forwarded-for">
2767 <title>change-x-forwarded-for</title>
2771 <term>Typical use:</term>
2773 <para>Improve privacy by not forwarding the source of the request in the HTTP headers.</para>
2778 <term>Effect:</term>
2781 Deletes the <quote>X-Forwarded-For:</quote> HTTP header from the client request,
2789 <!-- Boolean, Parameterized, Multi-value -->
2791 <para>Parameterized.</para>
2796 <term>Parameter:</term>
2800 <para><quote>block</quote> to delete the header.</para>
2804 <quote>add</quote> to create the header (or append
2805 the client's IP address to an already existing one).
2816 It is safe and recommended to use <literal>block</literal>.
2819 Forwarding the source address of the request may make
2820 sense in some multi-user setups but is also a privacy risk.
2825 <term>Example usage:</term>
2828 <screen>+change-x-forwarded-for{block}</screen>
2835 <!-- ~~~~~ New section ~~~~~ -->
2836 <sect3 renderas="sect4" id="client-header-filter">
2837 <title>client-header-filter</title>
2841 <term>Typical use:</term>
2844 Rewrite or remove single client headers.
2850 <term>Effect:</term>
2853 All client headers to which this action applies are filtered on-the-fly through
2854 the specified regular expression based substitutions.
2861 <!-- boolean, parameterized, Multi-value -->
2863 <para>Multi-value.</para>
2868 <term>Parameter:</term>
2871 The name of a client-header filter, as defined in one of the
2872 <link linkend="filter-file">filter files</link>.
2881 Client-header filters are applied to each header on its own, not to
2882 all at once. This makes it easier to diagnose problems, but on the downside
2883 you can't write filters that only change header x if header y's value is z.
2884 You can do that by using tags though.
2887 Client-header filters are executed after the other header actions have finished
2888 and use their output as input.
2891 If the request URI gets changed, &my-app; will detect that and use the new
2892 one. This can be used to rewrite the request destination behind the client's
2893 back, for example to specify a Tor exit relay for certain requests.
2896 Please refer to the <link linkend="filter-file">filter file chapter</link>
2897 to learn which client-header filters are available by default, and how to
2905 <term>Example usage (section):</term>
2909 # Hide Tor exit notation in Host and Referer Headers
2910 {+client-header-filter{hide-tor-exit-notation}}
2921 <!-- ~~~~~ New section ~~~~~ -->
2922 <sect3 renderas="sect4" id="client-header-tagger">
2923 <title>client-header-tagger</title>
2927 <term>Typical use:</term>
2930 Block requests based on their headers.
2936 <term>Effect:</term>
2939 Client headers to which this action applies are filtered on-the-fly through
2940 the specified regular expression based substitutions, the result is used as
2948 <!-- boolean, parameterized, Multi-value -->
2950 <para>Multi-value.</para>
2955 <term>Parameter:</term>
2958 The name of a client-header tagger, as defined in one of the
2959 <link linkend="filter-file">filter files</link>.
2968 Client-header taggers are applied to each header on its own,
2969 and as the header isn't modified, each tagger <quote>sees</quote>
2973 Client-header taggers are the first actions that are executed
2974 and their tags can be used to control every other action.
2980 <term>Example usage (section):</term>
2984 # Tag every request with the User-Agent header
2985 {+client-header-tagger{user-agent}}
2988 # Tagging itself doesn't change the action
2989 # settings, sections with TAG patterns do:
2991 # If it's a download agent, use a different forwarding proxy,
2992 # show the real User-Agent and make sure resume works.
2993 {+forward-override{forward-socks5 10.0.0.2:2222 .} \
2994 -hide-if-modified-since \
2995 -overwrite-last-modified \
3000 TAG:^User-Agent: NetBSD-ftp/
3001 TAG:^User-Agent: Novell ZYPP Installer
3002 TAG:^User-Agent: RPM APT-HTTP/
3003 TAG:^User-Agent: fetch libfetch/
3004 TAG:^User-Agent: Ubuntu APT-HTTP/
3005 TAG:^User-Agent: MPlayer/
3010 # Tag all requests with the Range header set
3011 {+client-header-tagger{range-requests}}
3014 # Disable filtering for the tagged requests.
3016 # With filtering enabled Privoxy would remove the Range headers
3017 # to be able to filter the whole response. The downside is that
3018 # it prevents clients from resuming downloads or skipping over
3019 # parts of multimedia files.
3020 {-filter -deanimate-gifs}
3026 # Tag all requests with the client IP address
3028 # (Technically the client IP address isn't included in the
3029 # client headers but client-header taggers can set it anyway.
3030 # For details see the tagger in default.filter)
3031 {+client-header-tagger{client-ip-address}}
3034 # Change forwarding settings for requests coming from address 10.0.0.1
3035 {+forward-override{forward-socks5 127.0.1.2:2222 .}}
3036 TAG:^IP-ADDRESS: 10\.0\.0\.1$
3046 <!-- ~~~~~ New section ~~~~~ -->
3047 <sect3 renderas="sect4" id="content-type-overwrite">
3048 <title>content-type-overwrite</title>
3052 <term>Typical use:</term>
3054 <para>Stop useless download menus from popping up, or change the browser's rendering mode</para>
3059 <term>Effect:</term>
3062 Replaces the <quote>Content-Type:</quote> HTTP server header.
3069 <!-- Boolean, Parameterized, Multi-value -->
3071 <para>Parameterized.</para>
3076 <term>Parameter:</term>
3088 The <quote>Content-Type:</quote> HTTP server header is used by the
3089 browser to decide what to do with the document. The value of this
3090 header can cause the browser to open a download menu instead of
3091 displaying the document by itself, even if the document's format is
3092 supported by the browser.
3095 The declared content type can also affect which rendering mode
3096 the browser chooses. If XHTML is delivered as <quote>text/html</quote>,
3097 many browsers treat it as yet another broken HTML document.
3098 If it is send as <quote>application/xml</quote>, browsers with
3099 XHTML support will only display it, if the syntax is correct.
3102 If you see a web site that proudly uses XHTML buttons, but sets
3103 <quote>Content-Type: text/html</quote>, you can use &my-app;
3104 to overwrite it with <quote>application/xml</quote> and validate
3105 the web master's claim inside your XHTML-supporting browser.
3106 If the syntax is incorrect, the browser will complain loudly.
3109 You can also go the opposite direction: if your browser prints
3110 error messages instead of rendering a document falsely declared
3111 as XHTML, you can overwrite the content type with
3112 <quote>text/html</quote> and have it rendered as broken HTML document.
3115 By default <literal>content-type-overwrite</literal> only replaces
3116 <quote>Content-Type:</quote> headers that look like some kind of text.
3117 If you want to overwrite it unconditionally, you have to combine it with
3118 <literal><link linkend="force-text-mode">force-text-mode</link></literal>.
3119 This limitation exists for a reason, think twice before circumventing it.
3122 Most of the time it's easier to replace this action with a custom
3123 <literal><link linkend="server-header-filter">server-header filter</link></literal>.
3124 It allows you to activate it for every document of a certain site and it will still
3125 only replace the content types you aimed at.
3128 Of course you can apply <literal>content-type-overwrite</literal>
3129 to a whole site and then make URL based exceptions, but it's a lot
3130 more work to get the same precision.
3136 <term>Example usage (sections):</term>
3139 <screen># Check if www.example.net/ really uses valid XHTML
3140 { +content-type-overwrite{application/xml} }
3143 # but leave the content type unmodified if the URL looks like a style sheet
3144 {-content-type-overwrite}
3145 www.example.net/.*\.css$
3146 www.example.net/.*style
3155 <!-- ~~~~~ New section ~~~~~ -->
3156 <sect3 renderas="sect4" id="crunch-client-header">
3160 <title>crunch-client-header</title>
3164 <term>Typical use:</term>
3166 <para>Remove a client header <application>Privoxy</application> has no dedicated action for.</para>
3171 <term>Effect:</term>
3174 Deletes every header sent by the client that contains the string the user supplied as parameter.
3181 <!-- Boolean, Parameterized, Multi-value -->
3183 <para>Parameterized.</para>
3188 <term>Parameter:</term>
3200 This action allows you to block client headers for which no dedicated
3201 <application>Privoxy</application> action exists.
3202 <application>Privoxy</application> will remove every client header that
3203 contains the string you supplied as parameter.
3206 Regular expressions are <emphasis>not supported</emphasis> and you can't
3207 use this action to block different headers in the same request, unless
3208 they contain the same string.
3211 <literal>crunch-client-header</literal> is only meant for quick tests.
3212 If you have to block several different headers, or only want to modify
3213 parts of them, you should use a
3214 <literal><link linkend="client-header-filter">client-header filter</link></literal>.
3218 Don't block any header without understanding the consequences.
3225 <term>Example usage (section):</term>
3228 <screen># Block the non-existent "Privacy-Violation:" client header
3229 { +crunch-client-header{Privacy-Violation:} }
3239 <!-- ~~~~~ New section ~~~~~ -->
3240 <sect3 renderas="sect4" id="crunch-if-none-match">
3241 <title>crunch-if-none-match</title>
3247 <term>Typical use:</term>
3249 <para>Prevent yet another way to track the user's steps between sessions.</para>
3254 <term>Effect:</term>
3257 Deletes the <quote>If-None-Match:</quote> HTTP client header.
3264 <!-- Boolean, Parameterized, Multi-value -->
3266 <para>Boolean.</para>
3271 <term>Parameter:</term>
3283 Removing the <quote>If-None-Match:</quote> HTTP client header
3284 is useful for filter testing, where you want to force a real
3285 reload instead of getting status code <quote>304</quote> which
3286 would cause the browser to use a cached copy of the page.
3289 It is also useful to make sure the header isn't used as a cookie
3290 replacement (unlikely but possible).
3293 Blocking the <quote>If-None-Match:</quote> header shouldn't cause any
3294 caching problems, as long as the <quote>If-Modified-Since:</quote> header
3295 isn't blocked or missing as well.
3298 It is recommended to use this action together with
3299 <literal><link linkend="hide-if-modified-since">hide-if-modified-since</link></literal>
3301 <literal><link linkend="overwrite-last-modified">overwrite-last-modified</link></literal>.
3307 <term>Example usage (section):</term>
3310 <screen># Let the browser revalidate cached documents but don't
3311 # allow the server to use the revalidation headers for user tracking.
3312 {+hide-if-modified-since{-60} \
3313 +overwrite-last-modified{randomize} \
3314 +crunch-if-none-match}
3323 <!-- ~~~~~ New section ~~~~~ -->
3324 <sect3 renderas="sect4" id="crunch-incoming-cookies">
3325 <title>crunch-incoming-cookies</title>
3329 <term>Typical use:</term>
3332 Prevent the web server from setting HTTP cookies on your system
3338 <term>Effect:</term>
3341 Deletes any <quote>Set-Cookie:</quote> HTTP headers from server replies.
3348 <!-- Boolean, Parameterized, Multi-value -->
3350 <para>Boolean.</para>
3355 <term>Parameter:</term>
3367 This action is only concerned with <emphasis>incoming</emphasis> HTTP cookies. For
3368 <emphasis>outgoing</emphasis> HTTP cookies, use
3369 <literal><link linkend="crunch-outgoing-cookies">crunch-outgoing-cookies</link></literal>.
3370 Use <emphasis>both</emphasis> to disable HTTP cookies completely.
3373 It makes <emphasis>no sense at all</emphasis> to use this action in conjunction
3374 with the <literal><link linkend="session-cookies-only">session-cookies-only</link></literal> action,
3375 since it would prevent the session cookies from being set. See also
3376 <literal><link linkend="filter-content-cookies">filter-content-cookies</link></literal>.
3382 <term>Example usage:</term>
3385 <screen>+crunch-incoming-cookies</screen>
3393 <!-- ~~~~~ New section ~~~~~ -->
3394 <sect3 renderas="sect4" id="crunch-server-header">
3395 <title>crunch-server-header</title>
3401 <term>Typical use:</term>
3403 <para>Remove a server header <application>Privoxy</application> has no dedicated action for.</para>
3408 <term>Effect:</term>
3411 Deletes every header sent by the server that contains the string the user supplied as parameter.
3418 <!-- Boolean, Parameterized, Multi-value -->
3420 <para>Parameterized.</para>
3425 <term>Parameter:</term>
3437 This action allows you to block server headers for which no dedicated
3438 <application>Privoxy</application> action exists. <application>Privoxy</application>
3439 will remove every server header that contains the string you supplied as parameter.
3442 Regular expressions are <emphasis>not supported</emphasis> and you can't
3443 use this action to block different headers in the same request, unless
3444 they contain the same string.
3447 <literal>crunch-server-header</literal> is only meant for quick tests.
3448 If you have to block several different headers, or only want to modify
3449 parts of them, you should use a custom
3450 <literal><link linkend="server-header-filter">server-header filter</link></literal>.
3454 Don't block any header without understanding the consequences.
3461 <term>Example usage (section):</term>
3464 <screen># Crunch server headers that try to prevent caching
3465 { +crunch-server-header{no-cache} }
3474 <!-- ~~~~~ New section ~~~~~ -->
3475 <sect3 renderas="sect4" id="crunch-outgoing-cookies">
3476 <title>crunch-outgoing-cookies</title>
3480 <term>Typical use:</term>
3483 Prevent the web server from reading any HTTP cookies from your system
3489 <term>Effect:</term>
3492 Deletes any <quote>Cookie:</quote> HTTP headers from client requests.
3499 <!-- Boolean, Parameterized, Multi-value -->
3501 <para>Boolean.</para>
3506 <term>Parameter:</term>
3518 This action is only concerned with <emphasis>outgoing</emphasis> HTTP cookies. For
3519 <emphasis>incoming</emphasis> HTTP cookies, use
3520 <literal><link linkend="crunch-incoming-cookies">crunch-incoming-cookies</link></literal>.
3521 Use <emphasis>both</emphasis> to disable HTTP cookies completely.
3524 It makes <emphasis>no sense at all</emphasis> to use this action in conjunction
3525 with the <literal><link linkend="session-cookies-only">session-cookies-only</link></literal> action,
3526 since it would prevent the session cookies from being read.
3532 <term>Example usage:</term>
3535 <screen>+crunch-outgoing-cookies</screen>
3544 <!-- ~~~~~ New section ~~~~~ -->
3545 <sect3 renderas="sect4" id="deanimate-gifs">
3546 <title>deanimate-gifs</title>
3550 <term>Typical use:</term>
3552 <para>Stop those annoying, distracting animated GIF images.</para>
3557 <term>Effect:</term>
3560 De-animate GIF animations, i.e. reduce them to their first or last image.
3567 <!-- boolean, parameterized, Multi-value -->
3569 <para>Parameterized.</para>
3574 <term>Parameter:</term>
3577 <quote>last</quote> or <quote>first</quote>
3586 This will also shrink the images considerably (in bytes, not pixels!). If
3587 the option <quote>first</quote> is given, the first frame of the animation
3588 is used as the replacement. If <quote>last</quote> is given, the last
3589 frame of the animation is used instead, which probably makes more sense for
3590 most banner animations, but also has the risk of not showing the entire
3591 last frame (if it is only a delta to an earlier frame).
3594 You can safely use this action with patterns that will also match non-GIF
3595 objects, because no attempt will be made at anything that doesn't look like
3602 <term>Example usage:</term>
3605 <screen>+deanimate-gifs{last}</screen>
3612 <!-- ~~~~~ New section ~~~~~ -->
3613 <sect3 renderas="sect4" id="downgrade-http-version">
3614 <title>downgrade-http-version</title>
3618 <term>Typical use:</term>
3620 <para>Work around (very rare) problems with HTTP/1.1</para>
3625 <term>Effect:</term>
3628 Downgrades HTTP/1.1 client requests and server replies to HTTP/1.0.
3635 <!-- boolean, parameterized, Multi-value -->
3637 <para>Boolean.</para>
3642 <term>Parameter:</term>
3654 This is a left-over from the time when <application>Privoxy</application>
3655 didn't support important HTTP/1.1 features well. It is left here for the
3656 unlikely case that you experience HTTP/1.1-related problems with some server
3660 Note that enabling this action is only a workaround. It should not
3661 be enabled for sites that work without it. While it shouldn't break
3662 any pages, it has an (usually negative) performance impact.
3665 If you come across a site where enabling this action helps, please report it,
3666 so the cause of the problem can be analyzed. If the problem turns out to be
3667 caused by a bug in <application>Privoxy</application> it should be
3668 fixed so the following release works without the work around.
3674 <term>Example usage (section):</term>
3677 <screen>{+downgrade-http-version}
3678 problem-host.example.com</screen>
3686 <!-- ~~~~~ New section ~~~~~ -->
3687 <sect3 renderas="sect4" id="external-filter">
3688 <title>external-filter</title>
3692 <term>Typical use:</term>
3694 <para>Modify content using a programming language of your choice.</para>
3699 <term>Effect:</term>
3702 All instances of text-based type, most notably HTML and JavaScript, to which
3703 this action applies, can be filtered on-the-fly through the specified external
3705 By default plain text documents are exempted from filtering, because web
3706 servers often use the <literal>text/plain</literal> MIME type for all files
3707 whose type they don't know.)
3714 <!-- boolean, parameterized, Multi-value -->
3716 <para>Multi-value.</para>
3721 <term>Parameter:</term>
3724 The name of an external content filter, as defined in the
3725 <link linkend="filter-file">filter file</link>.
3726 External filters can be defined in one or more files as defined by the
3727 <literal><link linkend="filterfile">filterfile</link></literal>
3728 option in the <link linkend="config">config file</link>.
3731 When used in its negative form,
3732 and without parameters, <emphasis>all</emphasis> filtering with external
3733 filters is completely disabled.
3742 External filters are scripts or programs that can modify the content in
3743 case common <literal><link linkend="filter">filters</link></literal>
3744 aren't powerful enough. With the exception that this action doesn't
3745 use pcrs-based filters, the notes in the
3746 <literal><link linkend="filter">filter</link></literal> section apply.
3750 Currently external filters are executed with &my-app;'s privileges.
3751 Only use external filters you understand and trust.
3755 This feature is experimental, the <literal><link
3756 linkend="external-filter-syntax">syntax</link></literal>
3757 may change in the future.
3764 <term>Example usage:</term>
3767 <screen>+external-filter{fancy-filter}</screen>
3774 <!-- ~~~~~ New section ~~~~~ -->
3775 <sect3 renderas="sect4" id="fast-redirects">
3776 <title>fast-redirects</title>
3780 <term>Typical use:</term>
3782 <para>Fool some click-tracking scripts and speed up indirect links.</para>
3787 <term>Effect:</term>
3790 Detects redirection URLs and redirects the browser without contacting
3791 the redirection server first.
3798 <!-- boolean, parameterized, Multi-value -->
3800 <para>Parameterized.</para>
3805 <term>Parameter:</term>
3810 <quote>simple-check</quote> to just search for the string <quote>http://</quote>
3811 to detect redirection URLs.
3816 <quote>check-decoded-url</quote> to decode URLs (if necessary) before searching
3817 for redirection URLs.
3828 Many sites, like yahoo.com, don't just link to other sites. Instead, they
3829 will link to some script on their own servers, giving the destination as a
3830 parameter, which will then redirect you to the final target. URLs
3831 resulting from this scheme typically look like:
3832 <quote>http://www.example.org/click-tracker.cgi?target=http%3a//www.example.net/</quote>.
3835 Sometimes, there are even multiple consecutive redirects encoded in the
3836 URL. These redirections via scripts make your web browsing more traceable,
3837 since the server from which you follow such a link can see where you go
3838 to. Apart from that, valuable bandwidth and time is wasted, while your
3839 browser asks the server for one redirect after the other. Plus, it feeds
3843 This feature is currently not very smart and is scheduled for improvement.
3844 If it is enabled by default, you will have to create some exceptions to
3845 this action. It can lead to failures in several ways:
3848 Not every URLs with other URLs as parameters is evil.
3849 Some sites offer a real service that requires this information to work.
3850 For example a validation service needs to know, which document to validate.
3851 <literal>fast-redirects</literal> assumes that every URL parameter that
3852 looks like another URL is a redirection target, and will always redirect to
3853 the last one. Most of the time the assumption is correct, but if it isn't,
3854 the user gets redirected anyway.
3857 Another failure occurs if the URL contains other parameters after the URL parameter.
3859 <quote>http://www.example.org/?redirect=http%3a//www.example.net/&foo=bar</quote>.
3860 contains the redirection URL <quote>http://www.example.net/</quote>,
3861 followed by another parameter. <literal>fast-redirects</literal> doesn't know that
3862 and will cause a redirect to <quote>http://www.example.net/&foo=bar</quote>.
3863 Depending on the target server configuration, the parameter will be silently ignored
3864 or lead to a <quote>page not found</quote> error. You can prevent this problem by
3865 first using the <literal><link linkend="redirect">redirect</link></literal> action
3866 to remove the last part of the URL, but it requires a little effort.
3869 To detect a redirection URL, <literal>fast-redirects</literal> only
3870 looks for the string <quote>http://</quote>, either in plain text
3871 (invalid but often used) or encoded as <quote>http%3a//</quote>.
3872 Some sites use their own URL encoding scheme, encrypt the address
3873 of the target server or replace it with a database id. In theses cases
3874 <literal>fast-redirects</literal> is fooled and the request reaches the
3875 redirection server where it probably gets logged.
3881 <term>Example usage:</term>
3885 { +fast-redirects{simple-check} }
3888 { +fast-redirects{check-decoded-url} }
3889 another.example.com/testing</screen>
3898 <!-- ~~~~~ New section ~~~~~ -->
3899 <sect3 renderas="sect4" id="filter">
3900 <title>filter</title>
3904 <term>Typical use:</term>
3906 <para>Get rid of HTML and JavaScript annoyances, banner advertisements (by size),
3907 do fun text replacements, add personalized effects, etc.</para>
3912 <term>Effect:</term>
3915 All instances of text-based type, most notably HTML and JavaScript, to which
3916 this action applies, can be filtered on-the-fly through the specified regular
3917 expression based substitutions. (Note: as of version 3.0.3 plain text documents
3918 are exempted from filtering, because web servers often use the
3919 <literal>text/plain</literal> MIME type for all files whose type they don't know.)
3926 <!-- boolean, parameterized, Multi-value -->
3928 <para>Multi-value.</para>
3933 <term>Parameter:</term>
3936 The name of a content filter, as defined in the <link linkend="filter-file">filter file</link>.
3937 Filters can be defined in one or more files as defined by the
3938 <literal><link linkend="filterfile">filterfile</link></literal>
3939 option in the <link linkend="config">config file</link>.
3940 <filename>default.filter</filename> is the collection of filters
3941 supplied by the developers. Locally defined filters should go
3942 in their own file, such as <filename>user.filter</filename>.
3945 When used in its negative form,
3946 and without parameters, <emphasis>all</emphasis> filtering is completely disabled.
3955 For your convenience, there are a number of pre-defined filters available
3956 in the distribution filter file that you can use. See the examples below for
3960 Filtering requires buffering the page content, which may appear to
3961 slow down page rendering since nothing is displayed until all content has
3962 passed the filters. (The total time until the page is completely rendered
3963 doesn't change much, but it may be perceived as slower since the page is
3964 not incrementally displayed.)
3965 This effect will be more noticeable on slower connections.
3968 <quote>Rolling your own</quote>
3969 filters requires a knowledge of
3970 <ulink url="http://en.wikipedia.org/wiki/Regular_expressions"><quote>Regular
3971 Expressions</quote></ulink> and
3972 <ulink url="http://en.wikipedia.org/wiki/Html"><quote>HTML</quote></ulink>.
3973 This is very powerful feature, and potentially very intrusive.
3974 Filters should be used with caution, and where an equivalent
3975 <quote>action</quote> is not available.
3978 The amount of data that can be filtered is limited to the
3979 <literal><link linkend="buffer-limit">buffer-limit</link></literal>
3980 option in the main <link linkend="config">config file</link>. The
3981 default is 4096 KB (4 Megs). Once this limit is exceeded, the buffered
3982 data, and all pending data, is passed through unfiltered.
3985 Inappropriate MIME types, such as zipped files, are not filtered at all.
3986 (Again, only text-based types except plain text). Encrypted SSL data
3987 (from HTTPS servers) cannot be filtered either, since this would violate
3988 the integrity of the secure transaction. In some situations it might
3989 be necessary to protect certain text, like source code, from filtering
3990 by defining appropriate <literal>-filter</literal> exceptions.
3993 Compressed content can't be filtered either, but if &my-app;
3994 is compiled with zlib support and a supported compression algorithm
3995 is used (gzip or deflate), &my-app; can first decompress the content
3999 If you use a &my-app; version without zlib support, but want filtering to work on
4000 as much documents as possible, even those that would normally be sent compressed,
4001 you must use the <literal><link linkend="prevent-compression">prevent-compression</link></literal>
4002 action in conjunction with <literal>filter</literal>.
4005 Content filtering can achieve some of the same effects as the
4006 <literal><link linkend="block">block</link></literal>
4007 action, i.e. it can be used to block ads and banners. But the mechanism
4008 works quite differently. One effective use, is to block ad banners
4009 based on their size (see below), since many of these seem to be somewhat
4013 <link linkend="contact">Feedback</link> with suggestions for new or
4014 improved filters is particularly welcome!
4017 The below list has only the names and a one-line description of each
4018 predefined filter. There are <link linkend="predefined-filters">more
4019 verbose explanations</link> of what these filters do in the <link
4020 linkend="filter-file">filter file chapter</link>.
4026 <term>Example usage (with filters from the distribution <filename>default.filter</filename> file).
4027 See <link linkend="PREDEFINED-FILTERS">the Predefined Filters section</link> for
4028 more explanation on each:</term>
4031 <anchor id="filter-js-annoyances">
4032 <screen>+filter{js-annoyances} # Get rid of particularly annoying JavaScript abuse.</screen>
4035 <anchor id="filter-js-events">
4036 <screen>+filter{js-events} # Kill JavaScript event bindings and timers (Radically destructive! Only for extra nasty sites).</screen>
4039 <anchor id="filter-html-annoyances">
4040 <screen>+filter{html-annoyances} # Get rid of particularly annoying HTML abuse.</screen>
4043 <anchor id="filter-content-cookies">
4044 <screen>+filter{content-cookies} # Kill cookies that come in the HTML or JS content.</screen>
4047 <anchor id="filter-refresh-tags">
4048 <screen>+filter{refresh-tags} # Kill automatic refresh tags if refresh time is larger than 9 seconds.</screen>
4051 <anchor id="filter-unsolicited-popups">
4052 <screen>+filter{unsolicited-popups} # Disable only unsolicited pop-up windows.</screen>
4055 <anchor id="filter-all-popups">
4056 <screen>+filter{all-popups} # Kill all popups in JavaScript and HTML.</screen>
4059 <anchor id="filter-img-reorder">
4060 <screen>+filter{img-reorder} # Reorder attributes in <img> tags to make the banners-by-* filters more effective.</screen>
4063 <anchor id="filter-banners-by-size">
4064 <screen>+filter{banners-by-size} # Kill banners by size.</screen>
4067 <anchor id="filter-banners-by-link">
4068 <screen>+filter{banners-by-link} # Kill banners by their links to known clicktrackers.</screen>
4071 <anchor id="filter-webbugs">
4072 <screen>+filter{webbugs} # Squish WebBugs (1x1 invisible GIFs used for user tracking).</screen>
4075 <anchor id="filter-tiny-textforms">
4076 <screen>+filter{tiny-textforms} # Extend those tiny textareas up to 40x80 and kill the hard wrap.</screen>
4079 <anchor id="filter-jumping-windows">
4080 <screen>+filter{jumping-windows} # Prevent windows from resizing and moving themselves.</screen>
4083 <anchor id="filter-frameset-borders">
4084 <screen>+filter{frameset-borders} # Give frames a border and make them resizable.</screen>
4087 <anchor id="filter-iframes">
4088 <screen>+filter{iframes} # Removes all detected iframes. Should only be enabled for individual sites.</screen>
4091 <anchor id="filter-demoronizer">
4092 <screen>+filter{demoronizer} # Fix MS's non-standard use of standard charsets.</screen>
4095 <anchor id="filter-shockwave-flash">
4096 <screen>+filter{shockwave-flash} # Kill embedded Shockwave Flash objects.</screen>
4099 <anchor id="filter-quicktime-kioskmode">
4100 <screen>+filter{quicktime-kioskmode} # Make Quicktime movies saveable.</screen>
4103 <anchor id="filter-fun">
4104 <screen>+filter{fun} # Text replacements for subversive browsing fun!</screen>
4107 <anchor id="filter-crude-parental">
4108 <screen>+filter{crude-parental} # Crude parental filtering. Note that this filter doesn't work reliably.</screen>
4111 <anchor id="filter-ie-exploits">
4112 <screen>+filter{ie-exploits} # Disable some known Internet Explorer bug exploits.</screen>
4115 <anchor id="filter-site-specifics">
4116 <screen>+filter{site-specifics} # Cure for site-specific problems. Don't apply generally!</screen>
4119 <anchor id="filter-no-ping">
4120 <screen>+filter{no-ping} # Removes non-standard ping attributes in <a> and <area> tags.</screen>
4123 <anchor id="filter-google">
4124 <screen>+filter{google} # CSS-based block for Google text ads. Also removes a width limitation and the toolbar advertisement.</screen>
4127 <anchor id="filter-yahoo">
4128 <screen>+filter{yahoo} # CSS-based block for Yahoo text ads. Also removes a width limitation.</screen>
4131 <anchor id="filter-msn">
4132 <screen>+filter{msn} # CSS-based block for MSN text ads. Also removes tracking URLs and a width limitation.</screen>
4135 <anchor id="filter-blogspot">
4136 <screen>+filter{blogspot} # Cleans up some Blogspot blogs. Read the fine print before using this.</screen>
4144 <!-- ~~~~~ New section ~~~~~ -->
4145 <sect3 renderas="sect4" id="force-text-mode">
4146 <title>force-text-mode</title>
4152 <term>Typical use:</term>
4154 <para>Force <application>Privoxy</application> to treat a document as if it was in some kind of <emphasis>text</emphasis> format. </para>
4159 <term>Effect:</term>
4162 Declares a document as text, even if the <quote>Content-Type:</quote> isn't detected as such.
4169 <!-- Boolean, Parameterized, Multi-value -->
4171 <para>Boolean.</para>
4176 <term>Parameter:</term>
4188 As explained <literal><link linkend="filter">above</link></literal>,
4189 <application>Privoxy</application> tries to only filter files that are
4190 in some kind of text format. The same restrictions apply to
4191 <literal><link linkend="content-type-overwrite">content-type-overwrite</link></literal>.
4192 <literal>force-text-mode</literal> declares a document as text,
4193 without looking at the <quote>Content-Type:</quote> first.
4197 Think twice before activating this action. Filtering binary data
4198 with regular expressions can cause file damage.
4205 <term>Example usage:</term>
4218 <!-- ~~~~~ New section ~~~~~ -->
4219 <sect3 renderas="sect4" id="forward-override">
4220 <title>forward-override</title>
4226 <term>Typical use:</term>
4228 <para>Change the forwarding settings based on User-Agent or request origin</para>
4233 <term>Effect:</term>
4236 Overrules the forward directives in the configuration file.
4243 <!-- Boolean, Parameterized, Multi-value -->
4245 <para>Parameterized.</para>
4250 <term>Parameter:</term>
4254 <para><quote>forward .</quote> to use a direct connection without any additional proxies.</para>
4258 <quote>forward 127.0.0.1:8123</quote> to use the HTTP proxy listening at 127.0.0.1 port 8123.
4263 <quote>forward-socks4a 127.0.0.1:9050 .</quote> to use the socks4a proxy listening at
4264 127.0.0.1 port 9050. Replace <quote>forward-socks4a</quote> with <quote>forward-socks4</quote>
4265 to use a socks4 connection (with local DNS resolution) instead, use <quote>forward-socks5</quote>
4266 for socks5 connections (with remote DNS resolution).
4271 <quote>forward-socks4a 127.0.0.1:9050 proxy.example.org:8000</quote> to use the socks4a proxy
4272 listening at 127.0.0.1 port 9050 to reach the HTTP proxy listening at proxy.example.org port 8000.
4273 Replace <quote>forward-socks4a</quote> with <quote>forward-socks4</quote> to use a socks4 connection
4274 (with local DNS resolution) instead, use <quote>forward-socks5</quote>
4275 for socks5 connections (with remote DNS resolution).
4280 <quote>forward-webserver 127.0.0.1:80</quote> to use the HTTP
4281 server listening at 127.0.0.1 port 80 without adjusting the
4285 This makes it more convenient to use Privoxy to make
4286 existing websites available as onion services as well.
4289 Many websites serve content with hardcoded URLs and
4290 can't be easily adjusted to change the domain based
4291 on the one used by the client.
4294 Putting Privoxy between Tor and the webserver (or an stunnel
4295 that forwards to the webserver) allows to rewrite headers and
4296 content to make client and server happy at the same time.
4299 Using Privoxy for webservers that are only reachable through
4300 onion addresses and whose location is supposed to be secret
4301 is not recommended and should not be necessary anyway.
4312 This action takes parameters similar to the
4313 <link linkend="forwarding">forward</link> directives in the configuration
4314 file, but without the URL pattern. It can be used as replacement, but normally it's only
4315 used in cases where matching based on the request URL isn't sufficient.
4319 Please read the description for the <link linkend="forwarding">forward</link> directives before
4320 using this action. Forwarding to the wrong people will reduce your privacy and increase the
4321 chances of man-in-the-middle attacks.
4324 If the ports are missing or invalid, default values will be used. This might change
4325 in the future and you shouldn't rely on it. Otherwise incorrect syntax causes Privoxy
4326 to exit. Due to design limitations, invalid parameter syntax isn't detected until the
4327 action is used the first time.
4330 Use the <ulink url="http://config.privoxy.org/show-url-info">show-url-info CGI page</ulink>
4331 to verify that your forward settings do what you thought the do.
4338 <term>Example usage:</term>
4342 # Use an ssh tunnel for requests previously tagged as
4343 # <quote>User-Agent: fetch libfetch/2.0</quote> and make sure
4344 # resuming downloads continues to work.
4346 # This way you can continue to use Tor for your normal browsing,
4347 # without overloading the Tor network with your FreeBSD ports updates
4348 # or downloads of bigger files like ISOs.
4350 # Note that HTTP headers are easy to fake and therefore their
4351 # values are as (un)trustworthy as your clients and users.
4352 {+forward-override{forward-socks5 10.0.0.2:2222 .} \
4353 -hide-if-modified-since \
4354 -overwrite-last-modified \
4356 TAG:^User-Agent: fetch libfetch/2\.0$
4365 <!-- ~~~~~ New section ~~~~~ -->
4366 <sect3 renderas="sect4" id="handle-as-empty-document">
4367 <title>handle-as-empty-document</title>
4373 <term>Typical use:</term>
4375 <para>Mark URLs that should be replaced by empty documents <emphasis>if they get blocked</emphasis></para>
4380 <term>Effect:</term>
4383 This action alone doesn't do anything noticeable. It just marks URLs.
4384 If the <literal><link linkend="block">block</link></literal> action <emphasis>also applies</emphasis>,
4385 the presence or absence of this mark decides whether an HTML <quote>BLOCKED</quote>
4386 page, or an empty document will be sent to the client as a substitute for the blocked content.
4387 The <emphasis>empty</emphasis> document isn't literally empty, but actually contains a single space.
4394 <!-- Boolean, Parameterized, Multi-value -->
4396 <para>Boolean.</para>
4401 <term>Parameter:</term>
4413 Some browsers complain about syntax errors if JavaScript documents
4414 are blocked with <application>Privoxy's</application>
4415 default HTML page; this option can be used to silence them.
4416 And of course this action can also be used to eliminate the &my-app;
4417 BLOCKED message in frames.
4420 The content type for the empty document can be specified with
4421 <literal><link linkend="content-type-overwrite">content-type-overwrite{}</link></literal>,
4422 but usually this isn't necessary.
4428 <term>Example usage:</term>
4431 <screen># Block all documents on example.org that end with ".js",
4432 # but send an empty document instead of the usual HTML message.
4433 {+block{Blocked JavaScript} +handle-as-empty-document}
4443 <!-- ~~~~~ New section ~~~~~ -->
4444 <sect3 renderas="sect4" id="handle-as-image">
4445 <title>handle-as-image</title>
4449 <term>Typical use:</term>
4451 <para>Mark URLs as belonging to images (so they'll be replaced by images <emphasis>if they do get blocked</emphasis>, rather than HTML pages)</para>
4456 <term>Effect:</term>
4459 This action alone doesn't do anything noticeable. It just marks URLs as images.
4460 If the <literal><link linkend="block">block</link></literal> action <emphasis>also applies</emphasis>,
4461 the presence or absence of this mark decides whether an HTML <quote>blocked</quote>
4462 page, or a replacement image (as determined by the <literal><link
4463 linkend="set-image-blocker">set-image-blocker</link></literal> action) will be sent to the
4464 client as a substitute for the blocked content.
4471 <!-- Boolean, Parameterized, Multi-value -->
4473 <para>Boolean.</para>
4478 <term>Parameter:</term>
4490 The below generic example section is actually part of <filename>default.action</filename>.
4491 It marks all URLs with well-known image file name extensions as images and should
4495 Users will probably only want to use the handle-as-image action in conjunction with
4496 <literal><link linkend="block">block</link></literal>, to block sources of banners, whose URLs don't
4497 reflect the file type, like in the second example section.
4500 Note that you cannot treat HTML pages as images in most cases. For instance, (in-line) ad
4501 frames require an HTML page to be sent, or they won't display properly.
4502 Forcing <literal>handle-as-image</literal> in this situation will not replace the
4503 ad frame with an image, but lead to error messages.
4509 <term>Example usage (sections):</term>
4512 <screen># Generic image extensions:
4515 /.*\.(gif|jpg|jpeg|png|bmp|ico)$
4517 # These don't look like images, but they're banners and should be
4518 # blocked as images:
4520 {+block{Nasty banners.} +handle-as-image}
4521 nasty-banner-server.example.com/junk.cgi\?output=trash
4530 <!-- ~~~~~ New section ~~~~~ -->
4531 <sect3 renderas="sect4" id="hide-accept-language">
4532 <title>hide-accept-language</title>
4538 <term>Typical use:</term>
4540 <para>Pretend to use different language settings.</para>
4545 <term>Effect:</term>
4548 Deletes or replaces the <quote>Accept-Language:</quote> HTTP header in client requests.
4555 <!-- Boolean, Parameterized, Multi-value -->
4557 <para>Parameterized.</para>
4562 <term>Parameter:</term>
4565 Keyword: <quote>block</quote>, or any user defined value.
4574 Faking the browser's language settings can be useful to make a
4575 foreign User-Agent set with
4576 <literal><link linkend="hide-user-agent">hide-user-agent</link></literal>
4580 However some sites with content in different languages check the
4581 <quote>Accept-Language:</quote> to decide which one to take by default.
4582 Sometimes it isn't possible to later switch to another language without
4583 changing the <quote>Accept-Language:</quote> header first.
4586 Therefore it's a good idea to either only change the
4587 <quote>Accept-Language:</quote> header to languages you understand,
4588 or to languages that aren't wide spread.
4591 Before setting the <quote>Accept-Language:</quote> header
4592 to a rare language, you should consider that it helps to
4593 make your requests unique and thus easier to trace.
4594 If you don't plan to change this header frequently,
4595 you should stick to a common language.
4601 <term>Example usage (section):</term>
4604 <screen># Pretend to use Canadian language settings.
4605 {+hide-accept-language{en-ca} \
4606 +hide-user-agent{Mozilla/5.0 (X11; U; OpenBSD i386; en-CA; rv:1.8.0.4) Gecko/20060628 Firefox/1.5.0.4} \
4616 <!-- ~~~~~ New section ~~~~~ -->
4617 <sect3 renderas="sect4" id="hide-content-disposition">
4618 <title>hide-content-disposition</title>
4624 <term>Typical use:</term>
4626 <para>Prevent download menus for content you prefer to view inside the browser.</para>
4631 <term>Effect:</term>
4634 Deletes or replaces the <quote>Content-Disposition:</quote> HTTP header set by some servers.
4641 <!-- Boolean, Parameterized, Multi-value -->
4643 <para>Parameterized.</para>
4648 <term>Parameter:</term>
4651 Keyword: <quote>block</quote>, or any user defined value.
4660 Some servers set the <quote>Content-Disposition:</quote> HTTP header for
4661 documents they assume you want to save locally before viewing them.
4662 The <quote>Content-Disposition:</quote> header contains the file name
4663 the browser is supposed to use by default.
4666 In most browsers that understand this header, it makes it impossible to
4667 <emphasis>just view</emphasis> the document, without downloading it first,
4668 even if it's just a simple text file or an image.
4671 Removing the <quote>Content-Disposition:</quote> header helps
4672 to prevent this annoyance, but some browsers additionally check the
4673 <quote>Content-Type:</quote> header, before they decide if they can
4674 display a document without saving it first. In these cases, you have
4675 to change this header as well, before the browser stops displaying
4679 It is also possible to change the server's file name suggestion
4680 to another one, but in most cases it isn't worth the time to set
4684 This action will probably be removed in the future,
4685 use server-header filters instead.
4691 <term>Example usage:</term>
4694 <screen># Disarm the download link in Sourceforge's patch tracker
4696 +content-type-overwrite{text/plain}\
4697 +hide-content-disposition{block} }
4698 .sourceforge.net/tracker/download\.php</screen>
4706 <!-- ~~~~~ New section ~~~~~ -->
4707 <sect3 renderas="sect4" id="hide-if-modified-since">
4708 <title>hide-if-modified-since</title>
4714 <term>Typical use:</term>
4716 <para>Prevent yet another way to track the user's steps between sessions.</para>
4721 <term>Effect:</term>
4724 Deletes the <quote>If-Modified-Since:</quote> HTTP client header or modifies its value.
4731 <!-- Boolean, Parameterized, Multi-value -->
4733 <para>Parameterized.</para>
4738 <term>Parameter:</term>
4741 Keyword: <quote>block</quote>, or a user defined value that specifies a range of hours.
4750 Removing this header is useful for filter testing, where you want to force a real
4751 reload instead of getting status code <quote>304</quote>, which would cause the
4752 browser to use a cached copy of the page.
4755 Instead of removing the header, <literal>hide-if-modified-since</literal> can
4756 also add or subtract a random amount of time to/from the header's value.
4757 You specify a range of minutes where the random factor should be chosen from and
4758 <application>Privoxy</application> does the rest. A negative value means
4759 subtracting, a positive value adding.
4762 Randomizing the value of the <quote>If-Modified-Since:</quote> makes
4763 it less likely that the server can use the time as a cookie replacement,
4764 but you will run into caching problems if the random range is too high.
4767 It is a good idea to only use a small negative value and let
4768 <literal><link linkend="overwrite-last-modified">overwrite-last-modified</link></literal>
4769 handle the greater changes.
4772 It is also recommended to use this action together with
4773 <literal><link linkend="crunch-if-none-match">crunch-if-none-match</link></literal>,
4774 otherwise it's more or less pointless.
4780 <term>Example usage (section):</term>
4783 <screen># Let the browser revalidate but make tracking based on the time less likely.
4784 {+hide-if-modified-since{-60} \
4785 +overwrite-last-modified{randomize} \
4786 +crunch-if-none-match}
4795 <!-- ~~~~~ New section ~~~~~ -->
4796 <sect3 renderas="sect4" id="hide-from-header">
4797 <title>hide-from-header</title>
4801 <term>Typical use:</term>
4803 <para>Keep your (old and ill) browser from telling web servers your email address</para>
4808 <term>Effect:</term>
4811 Deletes any existing <quote>From:</quote> HTTP header, or replaces it with the
4819 <!-- Boolean, Parameterized, Multi-value -->
4821 <para>Parameterized.</para>
4826 <term>Parameter:</term>
4829 Keyword: <quote>block</quote>, or any user defined value.
4838 The keyword <quote>block</quote> will completely remove the header
4839 (not to be confused with the <literal><link linkend="block">block</link></literal>
4843 Alternately, you can specify any value you prefer to be sent to the web
4844 server. If you do, it is a matter of fairness not to use any address that
4845 is actually used by a real person.
4848 This action is rarely needed, as modern web browsers don't send
4849 <quote>From:</quote> headers anymore.
4855 <term>Example usage:</term>
4858 <screen>+hide-from-header{block}</screen> or
4859 <screen>+hide-from-header{spam-me-senseless@sittingduck.example.com}</screen>
4867 <!-- ~~~~~ New section ~~~~~ -->
4868 <sect3 renderas="sect4" id="hide-referrer">
4869 <title>hide-referrer</title>
4870 <anchor id="hide-referer">
4873 <term>Typical use:</term>
4875 <para>Conceal which link you followed to get to a particular site</para>
4880 <term>Effect:</term>
4883 Deletes the <quote>Referer:</quote> (sic) HTTP header from the client request,
4884 or replaces it with a forged one.
4891 <!-- Boolean, Parameterized, Multi-value -->
4893 <para>Parameterized.</para>
4898 <term>Parameter:</term>
4902 <para><quote>conditional-block</quote> to delete the header completely if the host has changed.</para>
4905 <para><quote>conditional-forge</quote> to forge the header if the host has changed.</para>
4908 <para><quote>block</quote> to delete the header unconditionally.</para>
4911 <para><quote>forge</quote> to pretend to be coming from the homepage of the server we are talking to.</para>
4914 <para>Any other string to set a user defined referrer.</para>
4924 <literal>conditional-block</literal> is the only parameter,
4925 that isn't easily detected in the server's log file. If it blocks the
4926 referrer, the request will look like the visitor used a bookmark or
4927 typed in the address directly.
4930 Leaving the referrer unmodified for requests on the same host
4931 allows the server owner to see the visitor's <quote>click path</quote>,
4932 but in most cases she could also get that information by comparing
4933 other parts of the log file: for example the User-Agent if it isn't
4934 a very common one, or the user's IP address if it doesn't change between
4938 Always blocking the referrer, or using a custom one, can lead to
4939 failures on servers that check the referrer before they answer any
4940 requests, in an attempt to prevent their content from being
4941 embedded or linked to elsewhere.
4944 Both <literal>conditional-block</literal> and <literal>forge</literal>
4945 will work with referrer checks, as long as content and valid referring page
4946 are on the same host. Most of the time that's the case.
4949 <literal>hide-referer</literal> is an alternate spelling of
4950 <literal>hide-referrer</literal> and the two can be can be freely
4951 substituted with each other. (<quote>referrer</quote> is the
4952 correct English spelling, however the HTTP specification has a bug - it
4953 requires it to be spelled as <quote>referer</quote>.)
4959 <term>Example usage:</term>
4962 <screen>+hide-referrer{forge}</screen> or
4963 <screen>+hide-referrer{http://www.yahoo.com/}</screen>
4971 <!-- ~~~~~ New section ~~~~~ -->
4972 <sect3 renderas="sect4" id="hide-user-agent">
4973 <title>hide-user-agent</title>
4977 <term>Typical use:</term>
4979 <para>Try to conceal your type of browser and client operating system</para>
4984 <term>Effect:</term>
4987 Replaces the value of the <quote>User-Agent:</quote> HTTP header
4988 in client requests with the specified value.
4995 <!-- Boolean, Parameterized, Multi-value -->
4997 <para>Parameterized.</para>
5002 <term>Parameter:</term>
5005 Any user-defined string.
5015 This can lead to problems on web sites that depend on looking at this header in
5016 order to customize their content for different browsers (which, by the
5017 way, is <emphasis>NOT</emphasis> the right thing to do: good web sites
5018 work browser-independently).
5022 Using this action in multi-user setups or wherever different types of
5023 browsers will access the same <application>Privoxy</application> is
5024 <emphasis>not recommended</emphasis>. In single-user, single-browser
5025 setups, you might use it to delete your OS version information from
5026 the headers, because it is an invitation to exploit known bugs for your
5027 OS. It is also occasionally useful to forge this in order to access
5028 sites that won't let you in otherwise (though there may be a good
5029 reason in some cases).
5032 More information on known user-agent strings can be found at
5033 <ulink url="http://www.user-agents.org/">http://www.user-agents.org/</ulink>
5035 <ulink url="http://en.wikipedia.org/wiki/User_agent">http://en.wikipedia.org/wiki/User_agent</ulink>.
5041 <term>Example usage:</term>
5044 <screen>+hide-user-agent{Netscape 6.1 (X11; I; Linux 2.4.18 i686)}</screen>
5052 <!-- ~~~~~ New section ~~~~~ -->
5053 <sect3 renderas="sect4" id="limit-connect">
5054 <title>limit-connect</title>
5058 <term>Typical use:</term>
5060 <para>Prevent abuse of <application>Privoxy</application> as a TCP proxy relay or disable SSL for untrusted sites</para>
5065 <term>Effect:</term>
5068 Specifies to which ports HTTP CONNECT requests are allowable.
5075 <!-- Boolean, Parameterized, Multi-value -->
5077 <para>Parameterized.</para>
5082 <term>Parameter:</term>
5085 A comma-separated list of ports or port ranges (the latter using dashes, with the minimum
5086 defaulting to 0 and the maximum to 65K).
5095 By default, i.e. if no <literal>limit-connect</literal> action applies,
5096 <application>Privoxy</application> allows HTTP CONNECT requests to all
5097 ports. Use <literal>limit-connect</literal> if fine-grained control
5098 is desired for some or all destinations.
5101 The CONNECT methods exists in HTTP to allow access to secure websites
5102 (<quote>https://</quote> URLs) through proxies. It works very simply:
5103 the proxy connects to the server on the specified port, and then
5104 short-circuits its connections to the client and to the remote server.
5105 This means CONNECT-enabled proxies can be used as TCP relays very easily.
5108 <application>Privoxy</application> relays HTTPS traffic without seeing
5109 the decoded content. Websites can leverage this limitation to circumvent &my-app;'s
5110 filters. By specifying an invalid port range you can disable HTTPS entirely.
5116 <term>Example usages:</term>
5118 <!-- I had trouble getting the spacing to look right in my browser -->
5119 <!-- I probably have the wrong font setup, bollocks. -->
5120 <!-- Apparently the emphasis tag uses a proportional font no matter what -->
5122 <screen>+limit-connect{443} # Port 443 is OK.
5123 +limit-connect{80,443} # Ports 80 and 443 are OK.
5124 +limit-connect{-3, 7, 20-100, 500-} # Ports less than 3, 7, 20 to 100 and above 500 are OK.
5125 +limit-connect{-} # All ports are OK
5126 +limit-connect{,} # No HTTPS/SSL traffic is allowed</screen>
5134 <!-- ~~~~~ New section ~~~~~ -->
5135 <sect3 renderas="sect4" id="limit-cookie-lifetime">
5136 <title>limit-cookie-lifetime</title>
5140 <term>Typical use:</term>
5142 <para>Limit the lifetime of HTTP cookies to a couple of minutes or hours.</para>
5147 <term>Effect:</term>
5150 Overwrites the expires field in Set-Cookie server headers if it's above the specified limit.
5157 <!-- Boolean, Parameterized, Multi-value -->
5159 <para>Parameterized.</para>
5164 <term>Parameter:</term>
5167 The lifetime limit in minutes, or 0.
5176 This action reduces the lifetime of HTTP cookies coming from the
5177 server to the specified number of minutes, starting from the time
5178 the cookie passes Privoxy.
5181 Cookies with a lifetime below the limit are not modified.
5182 The lifetime of session cookies is set to the specified limit.
5185 The effect of this action depends on the server.
5188 In case of servers which refresh their cookies with each response
5189 (or at least frequently), the lifetime limit set by this action
5191 Thus, a session associated with the cookie continues to work with
5192 this action enabled, as long as a new request is made before the
5193 last limit set is reached.
5196 However, some servers send their cookies once, with a lifetime of several
5197 years (the year 2037 is a popular choice), and do not refresh them
5198 until a certain event in the future, for example the user logging out.
5199 In this case this action may limit the absolute lifetime of the session,
5200 even if requests are made frequently.
5203 If the parameter is <quote>0</quote>, this action behaves like
5204 <literal><link linkend="session-cookies-only">session-cookies-only</link></literal>.
5210 <term>Example usages:</term>
5213 <screen>+limit-cookie-lifetime{60}
5221 <!-- ~~~~~ New section ~~~~~ -->
5222 <sect3 renderas="sect4" id="prevent-compression">
5223 <title>prevent-compression</title>
5227 <term>Typical use:</term>
5230 Ensure that servers send the content uncompressed, so it can be
5231 passed through <literal><link linkend="filter">filter</link></literal>s.
5237 <term>Effect:</term>
5240 Removes the Accept-Encoding header which can be used to ask for compressed transfer.
5247 <!-- Boolean, Parameterized, Multi-value -->
5249 <para>Boolean.</para>
5254 <term>Parameter:</term>
5266 More and more websites send their content compressed by default, which
5267 is generally a good idea and saves bandwidth. But the <literal><link
5268 linkend="filter">filter</link></literal> and
5269 <literal><link linkend="deanimate-gifs">deanimate-gifs</link></literal>
5270 actions need access to the uncompressed data.
5273 When compiled with zlib support (available since &my-app; 3.0.7), content that should be
5274 filtered is decompressed on-the-fly and you don't have to worry about this action.
5275 If you are using an older &my-app; version, or one that hasn't been compiled with zlib
5276 support, this action can be used to convince the server to send the content uncompressed.
5279 Most text-based instances compress very well, the size is seldom decreased by less than 50%,
5280 for markup-heavy instances like news feeds saving more than 90% of the original size isn't
5284 Not using compression will therefore slow down the transfer, and you should only
5285 enable this action if you really need it. As of &my-app; 3.0.7 it's disabled in all
5286 predefined action settings.
5289 Note that some (rare) ill-configured sites don't handle requests for uncompressed
5290 documents correctly. Broken PHP applications tend to send an empty document body,
5291 some IIS versions only send the beginning of the content. If you enable
5292 <literal>prevent-compression</literal> per default, you might want to add
5293 exceptions for those sites. See the example for how to do that.
5299 <term>Example usage (sections):</term>
5303 # Selectively turn off compression, and enable a filter
5305 { +filter{tiny-textforms} +prevent-compression }
5306 # Match only these sites
5311 # Or instead, we could set a universal default:
5313 { +prevent-compression }
5316 # Then maybe make exceptions for broken sites:
5318 { -prevent-compression }
5319 .compusa.com/</screen>
5328 <!-- ~~~~~ New section ~~~~~ -->
5329 <sect3 renderas="sect4" id="overwrite-last-modified">
5330 <title>overwrite-last-modified</title>
5336 <term>Typical use:</term>
5338 <para>Prevent yet another way to track the user's steps between sessions.</para>
5343 <term>Effect:</term>
5346 Deletes the <quote>Last-Modified:</quote> HTTP server header or modifies its value.
5353 <!-- Boolean, Parameterized, Multi-value -->
5355 <para>Parameterized.</para>
5360 <term>Parameter:</term>
5363 One of the keywords: <quote>block</quote>, <quote>reset-to-request-time</quote>
5364 and <quote>randomize</quote>
5373 Removing the <quote>Last-Modified:</quote> header is useful for filter
5374 testing, where you want to force a real reload instead of getting status
5375 code <quote>304</quote>, which would cause the browser to reuse the old
5376 version of the page.
5379 The <quote>randomize</quote> option overwrites the value of the
5380 <quote>Last-Modified:</quote> header with a randomly chosen time
5381 between the original value and the current time. In theory the server
5382 could send each document with a different <quote>Last-Modified:</quote>
5383 header to track visits without using cookies. <quote>Randomize</quote>
5384 makes it impossible and the browser can still revalidate cached documents.
5387 <quote>reset-to-request-time</quote> overwrites the value of the
5388 <quote>Last-Modified:</quote> header with the current time. You could use
5389 this option together with
5390 <literal><link linkend="hide-if-modified-since">hide-if-modified-since</link></literal>
5391 to further customize your random range.
5394 The preferred parameter here is <quote>randomize</quote>. It is safe
5395 to use, as long as the time settings are more or less correct.
5396 If the server sets the <quote>Last-Modified:</quote> header to the time
5397 of the request, the random range becomes zero and the value stays the same.
5398 Therefore you should later randomize it a second time with
5399 <literal><link linkend="hide-if-modified-since">hided-if-modified-since</link></literal>,
5403 It is also recommended to use this action together with
5404 <literal><link linkend="crunch-if-none-match">crunch-if-none-match</link></literal>.
5410 <term>Example usage:</term>
5413 <screen># Let the browser revalidate without being tracked across sessions
5414 { +hide-if-modified-since{-60} \
5415 +overwrite-last-modified{randomize} \
5416 +crunch-if-none-match}
5425 <!-- ~~~~~ New section ~~~~~ -->
5426 <sect3 renderas="sect4" id="redirect">
5427 <title>redirect</title>
5433 <term>Typical use:</term>
5436 Redirect requests to other sites.
5442 <term>Effect:</term>
5445 Convinces the browser that the requested document has been moved
5446 to another location and the browser should get it from there.
5453 <!-- Boolean, Parameterized, Multi-value -->
5455 <para>Parameterized</para>
5460 <term>Parameter:</term>
5463 An absolute URL or a single pcrs command.
5472 Requests to which this action applies are answered with a
5473 HTTP redirect to URLs of your choosing. The new URL is
5474 either provided as parameter, or derived by applying a
5475 single pcrs command to the original URL.
5478 The syntax for pcrs commands is documented in the
5479 <link linkend="filter-file">filter file</link> section.
5482 Requests can't be blocked and redirected at the same time,
5483 applying this action together with
5484 <literal><link linkend="block">block</link></literal>
5485 is a configuration error. Currently the request is blocked
5486 and an error message logged, the behavior may change in the
5487 future and result in Privoxy rejecting the action file.
5490 This action can be combined with
5491 <literal><link linkend="fast-redirects">fast-redirects{check-decoded-url}</link></literal>
5492 to redirect to a decoded version of a rewritten URL.
5495 Use this action carefully, make sure not to create redirection loops
5496 and be aware that using your own redirects might make it
5497 possible to fingerprint your requests.
5500 In case of problems with your redirects, or simply to watch
5501 them working, enable <link linkend="DEBUG">debug 128</link>.
5507 <term>Example usages:</term>
5510 <screen># Replace example.com's style sheet with another one
5511 { +redirect{http://localhost/css-replacements/example.com.css} }
5512 example.com/stylesheet\.css
5514 # Create a short, easy to remember nickname for a favorite site
5515 # (relies on the browser to accept and forward invalid URLs to &my-app;)
5516 { +redirect{https://www.privoxy.org/user-manual/actions-file.html} }
5519 # Always use the expanded view for Undeadly.org articles
5520 # (Note the $ at the end of the URL pattern to make sure
5521 # the request for the rewritten URL isn't redirected as well)
5522 {+redirect{s@$@&mode=expanded@}}
5523 undeadly.org/cgi\?action=article&sid=\d*$
5525 # Redirect Google search requests to MSN
5526 {+redirect{s@^http://[^/]*/search\?q=([^&]*).*@http://search.msn.com/results.aspx?q=$1@}}
5529 # Redirect MSN search requests to Yahoo
5530 {+redirect{s@^http://[^/]*/results\.aspx\?q=([^&]*).*@http://search.yahoo.com/search?p=$1@}}
5531 search.msn.com//results\.aspx\?q=
5533 # Redirect http://example.com/&bla=fasel&toChange=foo (and any other value but "bar")
5534 # to http://example.com/&bla=fasel&toChange=bar
5536 # The URL pattern makes sure that the following request isn't redirected again.
5537 {+redirect{s@toChange=[^&]+@toChange=bar@}}
5538 example.com/.*toChange=(?!bar)
5540 # Add a shortcut to look up illumos bugs
5541 {+redirect{s@^http://i([0-9]+)/.*@https://www.illumos.org/issues/$1@}}
5542 # Redirected URL = http://i4974/
5543 # Redirect Destination = https://www.illumos.org/issues/4974
5544 i[0-9][0-9][0-9][0-9]*/
5546 # Redirect remote requests for this manual
5547 # to the local version delivered by Privoxy
5548 {+redirect{s@^http://www@http://config@}}
5549 www.privoxy.org/user-manual/</screen>
5558 <!-- ~~~~~ New section ~~~~~ -->
5559 <sect3 renderas="sect4" id="server-header-filter">
5560 <title>server-header-filter</title>
5564 <term>Typical use:</term>
5567 Rewrite or remove single server headers.
5573 <term>Effect:</term>
5576 All server headers to which this action applies are filtered on-the-fly
5577 through the specified regular expression based substitutions.
5584 <!-- boolean, parameterized, Multi-value -->
5586 <para>Multi-value.</para>
5591 <term>Parameter:</term>
5594 The name of a server-header filter, as defined in one of the
5595 <link linkend="filter-file">filter files</link>.
5604 Server-header filters are applied to each header on its own, not to
5605 all at once. This makes it easier to diagnose problems, but on the downside
5606 you can't write filters that only change header x if header y's value is z.
5607 You can do that by using tags though.
5610 Server-header filters are executed after the other header actions have finished
5611 and use their output as input.
5614 Please refer to the <link linkend="filter-file">filter file chapter</link>
5615 to learn which server-header filters are available by default, and how to
5622 <term>Example usage (section):</term>
5626 {+server-header-filter{html-to-xml}}
5627 example.org/xml-instance-that-is-delivered-as-html
5629 {+server-header-filter{xml-to-html}}
5630 example.org/instance-that-is-delivered-as-xml-but-is-not
5640 <!-- ~~~~~ New section ~~~~~ -->
5641 <sect3 renderas="sect4" id="server-header-tagger">
5642 <title>server-header-tagger</title>
5646 <term>Typical use:</term>
5649 Enable or disable filters based on the Content-Type header.
5655 <term>Effect:</term>
5658 Server headers to which this action applies are filtered on-the-fly through
5659 the specified regular expression based substitutions, the result is used as
5667 <!-- boolean, parameterized, Multi-value -->
5669 <para>Multi-value.</para>
5674 <term>Parameter:</term>
5677 The name of a server-header tagger, as defined in one of the
5678 <link linkend="filter-file">filter files</link>.
5687 Server-header taggers are applied to each header on its own,
5688 and as the header isn't modified, each tagger <quote>sees</quote>
5692 Server-header taggers are executed before all other header actions
5693 that modify server headers. Their tags can be used to control
5694 all of the other server-header actions, the content filters
5695 and the crunch actions (<link linkend="redirect">redirect</link>
5696 and <link linkend="block">block</link>).
5699 Obviously crunching based on tags created by server-header taggers
5700 doesn't prevent the request from showing up in the server's log file.
5707 <term>Example usage (section):</term>
5711 # Tag every request with the content type declared by the server
5712 {+server-header-tagger{content-type}}
5715 # If the response has a tag starting with 'image/' enable an external
5716 # filter that only applies to images.
5718 # Note that the filter is not available by default, it's just a
5719 # <literal><link linkend="external-filter-syntax">silly example</link></literal>.
5720 {+external-filter{rotate-image} +force-text-mode}
5731 <!-- ~~~~~ New section ~~~~~ -->
5732 <sect3 renderas="sect4" id="session-cookies-only">
5733 <title>session-cookies-only</title>
5737 <term>Typical use:</term>
5740 Allow only temporary <quote>session</quote> cookies (for the current
5741 browser session <emphasis>only</emphasis>).
5747 <term>Effect:</term>
5750 Deletes the <quote>expires</quote> field from <quote>Set-Cookie:</quote>
5751 server headers. Most browsers will not store such cookies permanently and
5752 forget them in between sessions.
5759 <!-- Boolean, Parameterized, Multi-value -->
5761 <para>Boolean.</para>
5766 <term>Parameter:</term>
5778 This is less strict than <literal><link linkend="crunch-incoming-cookies">crunch-incoming-cookies</link></literal> /
5779 <literal><link linkend="crunch-outgoing-cookies">crunch-outgoing-cookies</link></literal> and allows you to browse
5780 websites that insist or rely on setting cookies, without compromising your privacy too badly.
5783 Most browsers will not permanently store cookies that have been processed by
5784 <literal>session-cookies-only</literal> and will forget about them between sessions.
5785 This makes profiling cookies useless, but won't break sites which require cookies so
5786 that you can log in for transactions. This is generally turned on for all
5787 sites, and is the recommended setting.
5790 It makes <emphasis>no sense at all</emphasis> to use <literal>session-cookies-only</literal>
5791 together with <literal><link linkend="crunch-incoming-cookies">crunch-incoming-cookies</link></literal> or
5792 <literal><link linkend="crunch-outgoing-cookies">crunch-outgoing-cookies</link></literal>. If you do, cookies
5793 will be plainly killed.
5796 Note that it is up to the browser how it handles such cookies without an <quote>expires</quote>
5797 field. If you use an exotic browser, you might want to try it out to be sure.
5800 This setting also has no effect on cookies that may have been stored
5801 previously by the browser before starting <application>Privoxy</application>.
5802 These would have to be removed manually.
5805 <application>Privoxy</application> also uses
5806 the <link linkend="filter-content-cookies">content-cookies filter</link>
5807 to block some types of cookies. Content cookies are not effected by
5808 <literal>session-cookies-only</literal>.
5814 <term>Example usage:</term>
5817 <screen>+session-cookies-only</screen>
5825 <!-- ~~~~~ New section ~~~~~ -->
5826 <sect3 renderas="sect4" id="set-image-blocker">
5827 <title>set-image-blocker</title>
5831 <term>Typical use:</term>
5833 <para>Choose the replacement for blocked images</para>
5838 <term>Effect:</term>
5841 This action alone doesn't do anything noticeable. If <emphasis>both</emphasis>
5842 <literal><link linkend="block">block</link></literal> <emphasis>and</emphasis> <literal><link
5843 linkend="handle-as-image">handle-as-image</link></literal> <emphasis>also</emphasis>
5844 apply, i.e. if the request is to be blocked as an image,
5845 <emphasis>then</emphasis> the parameter of this action decides what will be
5846 sent as a replacement.
5853 <!-- Boolean, Parameterized, Multi-value -->
5855 <para>Parameterized.</para>
5860 <term>Parameter:</term>
5865 <quote>pattern</quote> to send a built-in checkerboard pattern image. The image is visually
5866 decent, scales very well, and makes it obvious where banners were busted.
5871 <quote>blank</quote> to send a built-in transparent image. This makes banners disappear
5872 completely, but makes it hard to detect where <application>Privoxy</application> has blocked
5873 images on a given page and complicates troubleshooting if <application>Privoxy</application>
5874 has blocked innocent images, like navigation icons.
5879 <quote><replaceable class="parameter">target-url</replaceable></quote> to
5880 send a redirect to <replaceable class="parameter">target-url</replaceable>. You can redirect
5881 to any image anywhere, even in your local filesystem via <quote>file:///</quote> URL.
5882 (But note that not all browsers support redirecting to a local file system).
5885 A good application of redirects is to use special <application>Privoxy</application>-built-in
5886 URLs, which send the built-in images, as <replaceable class="parameter">target-url</replaceable>.
5887 This has the same visual effect as specifying <quote>blank</quote> or <quote>pattern</quote> in
5888 the first place, but enables your browser to cache the replacement image, instead of requesting
5889 it over and over again.
5900 The URLs for the built-in images are <quote>http://config.privoxy.org/send-banner?type=<replaceable
5901 class="parameter">type</replaceable></quote>, where <replaceable class="parameter">type</replaceable> is
5902 either <quote>blank</quote> or <quote>pattern</quote>.
5905 There is a third (advanced) type, called <quote>auto</quote>. It is <emphasis>NOT</emphasis> to be
5906 used in <literal>set-image-blocker</literal>, but meant for use from <link linkend="filter-file">filters</link>.
5907 Auto will select the type of image that would have applied to the referring page, had it been an image.
5913 <term>Example usage:</term>
5919 <screen>+set-image-blocker{pattern}</screen>
5922 Redirect to the BSD daemon:
5925 <screen>+set-image-blocker{http://www.freebsd.org/gifs/dae_up3.gif}</screen>
5928 Redirect to the built-in pattern for better caching:
5931 <screen>+set-image-blocker{http://config.privoxy.org/send-banner?type=pattern}</screen>
5939 <!-- ~~~~~ New section ~~~~~ -->
5940 <sect3 id="summary">
5941 <title>Summary</title>
5943 Note that many of these actions have the potential to cause a page to
5944 misbehave, possibly even not to display at all. There are many ways
5945 a site designer may choose to design his site, and what HTTP header
5946 content, and other criteria, he may depend on. There is no way to have hard
5947 and fast rules for all sites. See the <link
5948 linkend="ACTIONSANAT">Appendix</link> for a brief example on troubleshooting
5954 <!-- ~~~~~ New section ~~~~~ -->
5955 <sect2 id="aliases">
5956 <title>Aliases</title>
5958 Custom <quote>actions</quote>, known to <application>Privoxy</application>
5959 as <quote>aliases</quote>, can be defined by combining other actions.
5960 These can in turn be invoked just like the built-in actions.
5961 Currently, an alias name can contain any character except space, tab,
5963 <quote>{</quote> and <quote>}</quote>, but we <emphasis>strongly
5964 recommend</emphasis> that you only use <quote>a</quote> to <quote>z</quote>,
5965 <quote>0</quote> to <quote>9</quote>, <quote>+</quote>, and <quote>-</quote>.
5966 Alias names are not case sensitive, and are not required to start with a
5967 <quote>+</quote> or <quote>-</quote> sign, since they are merely textually
5971 Aliases can be used throughout the actions file, but they <emphasis>must be
5972 defined in a special section at the top of the file!</emphasis>
5973 And there can only be one such section per actions file. Each actions file may
5974 have its own alias section, and the aliases defined in it are only visible
5978 There are two main reasons to use aliases: One is to save typing for frequently
5979 used combinations of actions, the other one is a gain in flexibility: If you
5980 decide once how you want to handle shops by defining an alias called
5981 <quote>shop</quote>, you can later change your policy on shops in
5982 <emphasis>one</emphasis> place, and your changes will take effect everywhere
5983 in the actions file where the <quote>shop</quote> alias is used. Calling aliases
5984 by their purpose also makes your actions files more readable.
5987 Currently, there is one big drawback to using aliases, though:
5988 <application>Privoxy</application>'s built-in web-based action file
5989 editor honors aliases when reading the actions files, but it expands
5990 them before writing. So the effects of your aliases are of course preserved,
5991 but the aliases themselves are lost when you edit sections that use aliases
5996 Now let's define some aliases...
6001 # Useful custom aliases we can use later.
6003 # Note the (required!) section header line and that this section
6004 # must be at the top of the actions file!
6008 # These aliases just save typing later:
6009 # (Note that some already use other aliases!)
6011 +crunch-all-cookies = +<link linkend="CRUNCH-INCOMING-COOKIES">crunch-incoming-cookies</link> +<link linkend="CRUNCH-OUTGOING-COOKIES">crunch-outgoing-cookies</link>
6012 -crunch-all-cookies = -<link linkend="CRUNCH-INCOMING-COOKIES">crunch-incoming-cookies</link> -<link linkend="CRUNCH-OUTGOING-COOKIES">crunch-outgoing-cookies</link>
6013 +block-as-image = +block{Blocked image.} +handle-as-image
6014 allow-all-cookies = -crunch-all-cookies -<link linkend="SESSION-COOKIES-ONLY">session-cookies-only</link> -<link linkend="FILTER-CONTENT-COOKIES">filter{content-cookies}</link>
6016 # These aliases define combinations of actions
6017 # that are useful for certain types of sites:
6019 fragile = -<link linkend="BLOCK">block</link> -<link linkend="FILTER">filter</link> -crunch-all-cookies -<link linkend="FAST-REDIRECTS">fast-redirects</link> -<link linkend="HIDE-REFERER">hide-referrer</link> -<link linkend="PREVENT-COMPRESSION">prevent-compression</link>
6021 shop = -crunch-all-cookies -<link linkend="FILTER-ALL-POPUPS">filter{all-popups}</link>
6023 # Short names for other aliases, for really lazy people ;-)
6025 c0 = +crunch-all-cookies
6026 c1 = -crunch-all-cookies</screen>
6030 ...and put them to use. These sections would appear in the lower part of an
6031 actions file and define exceptions to the default actions (as specified further
6032 up for the <quote>/</quote> pattern):
6037 # These sites are either very complex or very keen on
6038 # user data and require minimal interference to work:
6041 .office.microsoft.com
6042 .windowsupdate.microsoft.com
6043 # Gmail is really mail.google.com, not gmail.com
6047 # Allow cookies (for setting and retrieving your customer data)
6051 .worldpay.com # for quietpc.com
6054 # These shops require pop-ups:
6056 {-filter{all-popups} -filter{unsolicited-popups}}
6058 .overclockers.co.uk</screen>
6062 Aliases like <quote>shop</quote> and <quote>fragile</quote> are typically used for
6063 <quote>problem</quote> sites that require more than one action to be disabled
6064 in order to function properly.
6070 <!-- ~~~~~ New section ~~~~~ -->
6071 <sect2 id="act-examples">
6072 <title>Actions Files Tutorial</title>
6074 The above chapters have shown <link linkend="actions-file">which actions files
6075 there are and how they are organized</link>, how actions are <link
6076 linkend="actions">specified</link> and <link linkend="actions-apply">applied
6077 to URLs</link>, how <link linkend="af-patterns">patterns</link> work, and how to
6078 define and use <link linkend="aliases">aliases</link>. Now, let's look at an
6079 example <filename>match-all.action</filename>, <filename>default.action</filename>
6080 and <filename>user.action</filename> file and see how all these pieces come together:
6083 <sect3 id="match-all">
6084 <title>match-all.action</title>
6086 Remember <emphasis>all actions are disabled when matching starts</emphasis>,
6087 so we have to explicitly enable the ones we want.
6091 While the <filename>match-all.action</filename> file only contains a
6092 single section, it is probably the most important one. It has only one
6093 pattern, <quote><literal>/</literal></quote>, but this pattern
6094 <link linkend="af-patterns">matches all URLs</link>. Therefore, the set of
6095 actions used in this <quote>default</quote> section <emphasis>will
6096 be applied to all requests as a start</emphasis>. It can be partly or
6097 wholly overridden by other actions files like <filename>default.action</filename>
6098 and <filename>user.action</filename>, but it will still be largely responsible
6099 for your overall browsing experience.
6103 Again, at the start of matching, all actions are disabled, so there is
6104 no need to disable any actions here. (Remember: a <quote>+</quote>
6105 preceding the action name enables the action, a <quote>-</quote> disables!).
6106 Also note how this long line has been made more readable by splitting it into
6107 multiple lines with line continuation.
6113 +<link linkend="CHANGE-X-FORWARDED-FOR">change-x-forwarded-for{block}</link> \
6114 +<link linkend="HIDE-FROM-HEADER">hide-from-header{block}</link> \
6115 +<link linkend="SET-IMAGE-BLOCKER">set-image-blocker{pattern}</link> \
6122 The default behavior is now set.
6126 <sect3 id="default-action">
6127 <title>default.action</title>
6130 If you aren't a developer, there's no need for you to edit the
6131 <filename>default.action</filename> file. It is maintained by
6132 the &my-app; developers and if you disagree with some of the
6133 sections, you should overrule them in your <filename>user.action</filename>.
6137 Understanding the <filename>default.action</filename> file can
6138 help you with your <filename>user.action</filename>, though.
6142 The first section in this file is a special section for internal use
6143 that prevents older &my-app; versions from reading the file:
6148 ##########################################################################
6149 # Settings -- Don't change! For internal Privoxy use ONLY.
6150 ##########################################################################
6152 for-privoxy-version=3.0.11</screen>
6156 After that comes the (optional) alias section. We'll use the example
6157 section from the above <link linkend="aliases">chapter on aliases</link>,
6158 that also explains why and how aliases are used:
6163 ##########################################################################
6165 ##########################################################################
6168 # These aliases just save typing later:
6169 # (Note that some already use other aliases!)
6171 +crunch-all-cookies = +<link linkend="CRUNCH-INCOMING-COOKIES">crunch-incoming-cookies</link> +<link linkend="CRUNCH-OUTGOING-COOKIES">crunch-outgoing-cookies</link>
6172 -crunch-all-cookies = -<link linkend="CRUNCH-INCOMING-COOKIES">crunch-incoming-cookies</link> -<link linkend="CRUNCH-OUTGOING-COOKIES">crunch-outgoing-cookies</link>
6173 +block-as-image = +block{Blocked image.} +handle-as-image
6174 mercy-for-cookies = -crunch-all-cookies -<link linkend="SESSION-COOKIES-ONLY">session-cookies-only</link> -<link linkend="FILTER-CONTENT-COOKIES">filter{content-cookies}</link>
6176 # These aliases define combinations of actions
6177 # that are useful for certain types of sites:
6179 fragile = -<link linkend="BLOCK">block</link> -<link linkend="FILTER">filter</link> -crunch-all-cookies -<link linkend="FAST-REDIRECTS">fast-redirects</link> -<link linkend="HIDE-REFERER">hide-referrer</link>
6180 shop = -crunch-all-cookies -<link linkend="FILTER-ALL-POPUPS">filter{all-popups}</link></screen>
6184 The first of our specialized sections is concerned with <quote>fragile</quote>
6185 sites, i.e. sites that require minimum interference, because they are either
6186 very complex or very keen on tracking you (and have mechanisms in place that
6187 make them unusable for people who avoid being tracked). We will use
6188 our pre-defined <literal>fragile</literal> alias instead of stating the list
6189 of actions explicitly:
6194 ##########################################################################
6195 # Exceptions for sites that'll break under the default action set:
6196 ##########################################################################
6198 # "Fragile" Use a minimum set of actions for these sites (see alias above):
6201 .office.microsoft.com # surprise, surprise!
6202 .windowsupdate.microsoft.com
6203 mail.google.com</screen>
6207 Shopping sites are not as fragile, but they typically
6208 require cookies to log in, and pop-up windows for shopping
6209 carts or item details. Again, we'll use a pre-defined alias:
6218 .worldpay.com # for quietpc.com
6220 .scan.co.uk</screen>
6224 The <literal><link linkend="FAST-REDIRECTS">fast-redirects</link></literal>
6225 action, which may have been enabled in <filename>match-all.action</filename>,
6226 breaks some sites. So disable it for popular sites where we know it misbehaves:
6231 { -<link linkend="FAST-REDIRECTS">fast-redirects</link> }
6235 .altavista.com/.*(like|url|link):http
6236 .altavista.com/trans.*urltext=http
6237 .nytimes.com</screen>
6241 It is important that <application>Privoxy</application> knows which
6242 URLs belong to images, so that <emphasis>if</emphasis> they are to
6243 be blocked, a substitute image can be sent, rather than an HTML page.
6244 Contacting the remote site to find out is not an option, since it
6245 would destroy the loading time advantage of banner blocking, and it
6246 would feed the advertisers information about you. We can mark any
6247 URL as an image with the <literal><link
6248 linkend="handle-as-image">handle-as-image</link></literal> action,
6249 and marking all URLs that end in a known image file extension is a
6255 ##########################################################################
6257 ##########################################################################
6259 # Define which file types will be treated as images, in case they get
6260 # blocked further down this file:
6262 { +<link linkend="HANDLE-AS-IMAGE">handle-as-image</link> }
6263 /.*\.(gif|jpe?g|png|bmp|ico)$</screen>
6267 And then there are known banner sources. They often use scripts to
6268 generate the banners, so it won't be visible from the URL that the
6269 request is for an image. Hence we block them <emphasis>and</emphasis>
6270 mark them as images in one go, with the help of our
6271 <literal>+block-as-image</literal> alias defined above. (We could of
6272 course just as well use <literal>+<link linkend="block">block</link>
6273 +<link linkend="handle-as-image">handle-as-image</link></literal> here.)
6274 Remember that the type of the replacement image is chosen by the
6275 <literal><link linkend="set-image-blocker">set-image-blocker</link></literal>
6276 action. Since all URLs have matched the default section with its
6277 <literal>+<link linkend="set-image-blocker">set-image-blocker</link>{pattern}</literal>
6278 action before, it still applies and needn't be repeated:
6283 # Known ad generators:
6288 .ad.*.doubleclick.net
6289 .a.yimg.com/(?:(?!/i/).)*$
6290 .a[0-9].yimg.com/(?:(?!/i/).)*$
6296 One of the most important jobs of <application>Privoxy</application>
6297 is to block banners. Many of these can be <quote>blocked</quote>
6298 by the <literal><link linkend="filter">filter</link>{banners-by-size}</literal>
6299 action, which we enabled above, and which deletes the references to banner
6300 images from the pages while they are loaded, so the browser doesn't request
6301 them anymore, and hence they don't need to be blocked here. But this naturally
6302 doesn't catch all banners, and some people choose not to use filters, so we
6303 need a comprehensive list of patterns for banner URLs here, and apply the
6304 <literal><link linkend="block">block</link></literal> action to them.
6307 First comes many generic patterns, which do most of the work, by
6308 matching typical domain and path name components of banners. Then comes
6309 a list of individual patterns for specific sites, which is omitted here
6310 to keep the example short:
6315 ##########################################################################
6316 # Block these fine banners:
6317 ##########################################################################
6318 { <link linkend="BLOCK">+block{Banner ads.}</link> }
6326 /.*count(er)?\.(pl|cgi|exe|dll|asp|php[34]?)
6327 /(?:.*/)?(publicite|werbung|rekla(ma|me|am)|annonse|maino(kset|nta|s)?)/
6329 # Site-specific patterns (abbreviated):
6331 .hitbox.com</screen>
6335 It's quite remarkable how many advertisers actually call their banner
6336 servers ads.<replaceable>company</replaceable>.com, or call the directory
6337 in which the banners are stored literally <quote>banners</quote>. So the above
6338 generic patterns are surprisingly effective.
6341 But being very generic, they necessarily also catch URLs that we don't want
6342 to block. The pattern <literal>.*ads.</literal> e.g. catches
6343 <quote>nasty-<emphasis>ads</emphasis>.nasty-corp.com</quote> as intended,
6344 but also <quote>downlo<emphasis>ads</emphasis>.sourcefroge.net</quote> or
6345 <quote><emphasis>ads</emphasis>l.some-provider.net.</quote> So here come some
6346 well-known exceptions to the <literal>+<link linkend="BLOCK">block</link></literal>
6350 Note that these are exceptions to exceptions from the default! Consider the URL
6351 <quote>downloads.sourcefroge.net</quote>: Initially, all actions are deactivated,
6352 so it wouldn't get blocked. Then comes the defaults section, which matches the
6353 URL, but just deactivates the <literal><link linkend="BLOCK">block</link></literal>
6354 action once again. Then it matches <literal>.*ads.</literal>, an exception to the
6355 general non-blocking policy, and suddenly
6356 <literal><link linkend="BLOCK">+block</link></literal> applies. And now, it'll match
6357 <literal>.*loads.</literal>, where <literal><link linkend="BLOCK">-block</link></literal>
6358 applies, so (unless it matches <emphasis>again</emphasis> further down) it ends up
6359 with no <literal><link linkend="BLOCK">block</link></literal> action applying.
6364 ##########################################################################
6365 # Save some innocent victims of the above generic block patterns:
6366 ##########################################################################
6370 { -<link linkend="BLOCK">block</link> }
6371 adv[io]*. # (for advogato.org and advice.*)
6372 adsl. # (has nothing to do with ads)
6373 adobe. # (has nothing to do with ads either)
6374 ad[ud]*. # (adult.* and add.*)
6375 .edu # (universities don't host banners (yet!))
6376 .*loads. # (downloads, uploads etc)
6384 www.globalintersec.com/adv # (adv = advanced)
6385 www.ugu.com/sui/ugu/adv</screen>
6389 Filtering source code can have nasty side effects,
6390 so make an exception for our friends at sourceforge.net,
6391 and all paths with <quote>cvs</quote> in them. Note that
6392 <literal>-<link linkend="FILTER">filter</link></literal>
6393 disables <emphasis>all</emphasis> filters in one fell swoop!
6398 # Don't filter code!
6400 { -<link linkend="FILTER">filter</link> }
6405 .sourceforge.net</screen>
6409 The actual <filename>default.action</filename> is of course much more
6410 comprehensive, but we hope this example made clear how it works.
6415 <sect3 id="user-action"><title>user.action</title>
6418 So far we are painting with a broad brush by setting general policies,
6419 which would be a reasonable starting point for many people. Now,
6420 you might want to be more specific and have customized rules that
6421 are more suitable to your personal habits and preferences. These would
6422 be for narrowly defined situations like your ISP or your bank, and should
6423 be placed in <filename>user.action</filename>, which is parsed after all other
6424 actions files and hence has the last word, over-riding any previously
6425 defined actions. <filename>user.action</filename> is also a
6426 <emphasis>safe</emphasis> place for your personal settings, since
6427 <filename>default.action</filename> is actively maintained by the
6428 <application>Privoxy</application> developers and you'll probably want
6429 to install updated versions from time to time.
6433 So let's look at a few examples of things that one might typically do in
6434 <filename>user.action</filename>:
6438 <!-- brief sample user.action here -->
6442 # My user.action file. <fred@example.com></screen>
6446 As <link linkend="aliases">aliases</link> are local to the actions
6447 file that they are defined in, you can't use the ones from
6448 <filename>default.action</filename>, unless you repeat them here:
6453 # Aliases are local to the file they are defined in.
6454 # (Re-)define aliases for this file:
6458 # These aliases just save typing later, and the alias names should
6459 # be self explanatory.
6461 +crunch-all-cookies = +crunch-incoming-cookies +crunch-outgoing-cookies
6462 -crunch-all-cookies = -crunch-incoming-cookies -crunch-outgoing-cookies
6463 allow-all-cookies = -crunch-all-cookies -session-cookies-only
6464 allow-popups = -filter{all-popups}
6465 +block-as-image = +block{Blocked as image.} +handle-as-image
6466 -block-as-image = -block
6468 # These aliases define combinations of actions that are useful for
6469 # certain types of sites:
6471 fragile = -block -crunch-all-cookies -filter -fast-redirects -hide-referrer
6472 shop = -crunch-all-cookies allow-popups
6474 # Allow ads for selected useful free sites:
6476 allow-ads = -block -filter{banners-by-size} -filter{banners-by-link}
6478 # Alias for specific file types that are text, but might have conflicting
6479 # MIME types. We want the browser to force these to be text documents.
6480 handle-as-text = -<link linkend="FILTER">filter</link> +-<link linkend="content-type-overwrite">content-type-overwrite{text/plain}</link> +-<link linkend="FORCE-TEXT-MODE">force-text-mode</link> -<link linkend="HIDE-CONTENT-DISPOSITION">hide-content-disposition</link></screen>
6485 Say you have accounts on some sites that you visit regularly, and
6486 you don't want to have to log in manually each time. So you'd like
6487 to allow persistent cookies for these sites. The
6488 <literal>allow-all-cookies</literal> alias defined above does exactly
6489 that, i.e. it disables crunching of cookies in any direction, and the
6490 processing of cookies to make them only temporary.
6495 { allow-all-cookies }
6499 .redhat.com</screen>
6503 Your bank is allergic to some filter, but you don't know which, so you disable them all:
6508 { -<link linkend="FILTER">filter</link> }
6509 .your-home-banking-site.com</screen>
6513 Some file types you may not want to filter for various reasons:
6518 # Technical documentation is likely to contain strings that might
6519 # erroneously get altered by the JavaScript-oriented filters:
6524 # And this stupid host sends streaming video with a wrong MIME type,
6525 # so that Privoxy thinks it is getting HTML and starts filtering:
6527 stupid-server.example.com/</screen>
6531 Example of a simple <link linkend="BLOCK">block</link> action. Say you've
6532 seen an ad on your favourite page on example.com that you want to get rid of.
6533 You have right-clicked the image, selected <quote>copy image location</quote>
6534 and pasted the URL below while removing the leading http://, into a
6535 <literal>{ +block{} }</literal> section. Note that <literal>{ +handle-as-image
6536 }</literal> need not be specified, since all URLs ending in
6537 <literal>.gif</literal> will be tagged as images by the general rules as set
6538 in default.action anyway:
6543 { +<link linkend="BLOCK">block</link>{Nasty ads.} }
6544 www.example.com/nasty-ads/sponsor\.gif
6545 another.example.net/more/junk/here/</screen>
6549 The URLs of dynamically generated banners, especially from large banner
6550 farms, often don't use the well-known image file name extensions, which
6551 makes it impossible for <application>Privoxy</application> to guess
6552 the file type just by looking at the URL.
6553 You can use the <literal>+block-as-image</literal> alias defined above for
6555 Note that objects which match this rule but then turn out NOT to be an
6556 image are typically rendered as a <quote>broken image</quote> icon by the
6557 browser. Use cautiously.
6566 ar.atwola.com/</screen>
6570 Now you noticed that the default configuration breaks Forbes Magazine,
6571 but you were too lazy to find out which action is the culprit, and you
6572 were again too lazy to give <link linkend="contact">feedback</link>, so
6573 you just used the <literal>fragile</literal> alias on the site, and
6574 -- <emphasis>whoa!</emphasis> -- it worked. The <literal>fragile</literal>
6575 aliases disables those actions that are most likely to break a site. Also,
6576 good for testing purposes to see if it is <application>Privoxy</application>
6577 that is causing the problem or not. We later find other regular sites
6578 that misbehave, and add those to our personalized list of troublemakers:
6586 .mybank.com</screen>
6590 You like the <quote>fun</quote> text replacements in <filename>default.filter</filename>,
6591 but it is disabled in the distributed actions file.
6592 So you'd like to turn it on in your private,
6593 update-safe config, once and for all:
6598 { +<link linkend="filter-fun">filter{fun}</link> }
6599 / # For ALL sites!</screen>
6603 Note that the above is not really a good idea: There are exceptions
6604 to the filters in <filename>default.action</filename> for things that
6605 really shouldn't be filtered, like code on CVS->Web interfaces. Since
6606 <filename>user.action</filename> has the last word, these exceptions
6607 won't be valid for the <quote>fun</quote> filtering specified here.
6611 You might also worry about how your favourite free websites are
6612 funded, and find that they rely on displaying banner advertisements
6613 to survive. So you might want to specifically allow banners for those
6614 sites that you feel provide value to you:
6626 Note that <literal>allow-ads</literal> has been aliased to
6627 <literal>-<link linkend="block">block</link></literal>,
6628 <literal>-<link linkend="filter-banners-by-size">filter{banners-by-size}</link></literal>, and
6629 <literal>-<link linkend="filter-banners-by-link">filter{banners-by-link}</link></literal> above.
6633 Invoke another alias here to force an over-ride of the MIME type <literal>
6634 application/x-sh</literal> which typically would open a download type
6635 dialog. In my case, I want to look at the shell script, and then I can save
6636 it should I choose to.
6646 <filename>user.action</filename> is generally the best place to define
6647 exceptions and additions to the default policies of
6648 <filename>default.action</filename>. Some actions are safe to have their
6649 default policies set here though. So let's set a default policy to have a
6650 <quote>blank</quote> image as opposed to the checkerboard pattern for
6651 <emphasis>ALL</emphasis> sites. <quote>/</quote> of course matches all URL
6657 { +<link linkend="set-image-blocker">set-image-blocker{blank}</link> }
6658 / # ALL sites</screen>
6664 <!-- ~ End section ~ -->
6668 <!-- ~ End section ~ -->
6670 <!-- ~~~~~~~~ New section Header ~~~~~~~~~ -->
6672 <sect1 id="filter-file">
6673 <title>Filter Files</title>
6676 On-the-fly text substitutions need
6677 to be defined in a <quote>filter file</quote>. Once defined, they
6678 can then be invoked as an <quote>action</quote>.
6682 &my-app; supports three different pcrs-based filter actions:
6683 <literal><link linkend="filter">filter</link></literal> to
6684 rewrite the content that is send to the client,
6685 <literal><link linkend="client-header-filter">client-header-filter</link></literal>
6686 to rewrite headers that are send by the client, and
6687 <literal><link linkend="server-header-filter">server-header-filter</link></literal>
6688 to rewrite headers that are send by the server.
6692 &my-app; also supports two tagger actions:
6693 <literal><link linkend="client-header-tagger">client-header-tagger</link></literal>
6695 <literal><link linkend="server-header-tagger">server-header-tagger</link></literal>.
6696 Taggers and filters use the same syntax in the filter files, the difference
6697 is that taggers don't modify the text they are filtering, but use a rewritten
6698 version of the filtered text as tag. The tags can then be used to change the
6699 applying actions through sections with <link linkend="tag-pattern">tag-patterns</link>.
6703 Finally &my-app; supports the
6704 <literal><link linkend="external-filter">external-filter</link></literal> action
6705 to enable <literal><link linkend="external-filter-syntax">external filters</link></literal>
6706 written in proper programming languages.
6711 Multiple filter files can be defined through the <literal> <link
6712 linkend="filterfile">filterfile</link></literal> config directive. The filters
6713 as supplied by the developers are located in
6714 <filename>default.filter</filename>. It is recommended that any locally
6715 defined or modified filters go in a separately defined file such as
6716 <filename>user.filter</filename>.
6720 Common tasks for content filters are to eliminate common annoyances in
6721 HTML and JavaScript, such as pop-up windows,
6722 exit consoles, crippled windows without navigation tools, the
6723 infamous <BLINK> tag etc, to suppress images with certain
6724 width and height attributes (standard banner sizes or web-bugs),
6725 or just to have fun.
6729 Enabled content filters are applied to any content whose
6730 <quote>Content Type</quote> header is recognised as a sign
6731 of text-based content, with the exception of <literal>text/plain</literal>.
6732 Use the <link linkend="FORCE-TEXT-MODE">force-text-mode</link> action
6733 to also filter other content.
6737 Substitutions are made at the source level, so if you want to <quote>roll
6738 your own</quote> filters, you should first be familiar with HTML syntax,
6739 and, of course, regular expressions.
6743 Just like the <link linkend="actions-file">actions files</link>, the
6744 filter file is organized in sections, which are called <emphasis>filters</emphasis>
6745 here. Each filter consists of a heading line, that starts with one of the
6746 <emphasis>keywords</emphasis> <literal>FILTER:</literal>,
6747 <literal>CLIENT-HEADER-FILTER:</literal> or <literal>SERVER-HEADER-FILTER:</literal>
6748 followed by the filter's <emphasis>name</emphasis>, and a short (one line)
6749 <emphasis>description</emphasis> of what it does. Below that line
6750 come the <emphasis>jobs</emphasis>, i.e. lines that define the actual
6751 text substitutions. By convention, the name of a filter
6752 should describe what the filter <emphasis>eliminates</emphasis>. The
6753 comment is used in the <ulink url="http://config.privoxy.org/">web-based
6754 user interface</ulink>.
6758 Once a filter called <replaceable>name</replaceable> has been defined
6759 in the filter file, it can be invoked by using an action of the form
6760 +<literal><link linkend="filter">filter</link>{<replaceable>name</replaceable>}</literal>
6761 in any <link linkend="actions-file">actions file</link>.
6765 Filter definitions start with a header line that contains the filter
6766 type, the filter name and the filter description.
6767 A content filter header line for a filter called <quote>foo</quote> could look
6772 <screen>FILTER: foo Replace all "foo" with "bar"</screen>
6776 Below that line, and up to the next header line, come the jobs that
6777 define what text replacements the filter executes. They are specified
6778 in a syntax that imitates <ulink url="http://www.perl.org/">Perl</ulink>'s
6779 <literal>s///</literal> operator. If you are familiar with Perl, you
6780 will find this to be quite intuitive, and may want to look at the
6781 PCRS documentation for the subtle differences to Perl behaviour.
6785 Most notably, the non-standard option letter <literal>U</literal> is supported,
6786 which turns the default to ungreedy matching (add <literal>?</literal> to
6787 quantifiers to turn them greedy again).
6791 The non-standard option letter <literal>D</literal> (dynamic) allows
6792 to use the variables $host, $origin (the IP address the request came from),
6793 $path, $url and $listen-address (the address on which Privoxy accepted the
6794 client request. Example: 127.0.0.1:8118).
6795 They will be replaced with the value they refer to before the filter
6800 Note that '$' is a bad choice for a delimiter in a dynamic filter as you
6801 might end up with unintended variables if you use a variable name
6802 directly after the delimiter. Variables will be resolved without
6803 escaping anything, therefore you also have to be careful not to chose
6804 delimiters that appear in the replacement text. For example '<' should
6805 be save, while '?' will sooner or later cause conflicts with $url.
6809 The non-standard option letter <literal>T</literal> (trivial) prevents
6810 parsing for backreferences in the substitute. Use it if you want to include
6811 text like '$&' in your substitute without quoting.
6816 <ulink url="http://en.wikipedia.org/wiki/Regular_expressions"><quote>Regular
6817 Expressions</quote></ulink>, you might want to take a look at
6818 the <link linkend="regex">Appendix on regular expressions</link>, and
6819 see the <ulink url="http://perldoc.perl.org/perlre.html">Perl
6821 <ulink url="http://perldoc.perl.org/perlop.html">the
6822 <literal>s///</literal> operator's syntax</ulink> and <ulink
6823 url="http://perldoc.perl.org/perlre.html">Perl-style regular
6824 expressions</ulink> in general.
6825 The below examples might also help to get you started.
6829 <!-- ~~~~~~~~ New section Header ~~~~~~~~~ -->
6831 <sect2 id="filter-file-tut"><title>Filter File Tutorial</title>
6833 Now, let's complete our <quote>foo</quote> content filter. We have already defined
6834 the heading, but the jobs are still missing. Since all it does is to replace
6835 <quote>foo</quote> with <quote>bar</quote>, there is only one (trivial) job
6840 <screen>s/foo/bar/</screen>
6844 But wait! Didn't the comment say that <emphasis>all</emphasis> occurrences
6845 of <quote>foo</quote> should be replaced? Our current job will only take
6846 care of the first <quote>foo</quote> on each page. For global substitution,
6847 we'll need to add the <literal>g</literal> option:
6851 <screen>s/foo/bar/g</screen>
6855 Our complete filter now looks like this:
6858 <screen>FILTER: foo Replace all "foo" with "bar"
6859 s/foo/bar/g</screen>
6863 Let's look at some real filters for more interesting examples. Here you see
6864 a filter that protects against some common annoyances that arise from JavaScript
6865 abuse. Let's look at its jobs one after the other:
6871 FILTER: js-annoyances Get rid of particularly annoying JavaScript abuse
6873 # Get rid of JavaScript referrer tracking. Test page: http://www.randomoddness.com/untitled.htm
6875 s|(<script.*)document\.referrer(.*</script>)|$1"Not Your Business!"$2|Usg</screen>
6879 Following the header line and a comment, you see the job. Note that it uses
6880 <literal>|</literal> as the delimiter instead of <literal>/</literal>, because
6881 the pattern contains a forward slash, which would otherwise have to be escaped
6882 by a backslash (<literal>\</literal>).
6886 Now, let's examine the pattern: it starts with the text <literal><script.*</literal>
6887 enclosed in parentheses. Since the dot matches any character, and <literal>*</literal>
6888 means: <quote>Match an arbitrary number of the element left of myself</quote>, this
6889 matches <quote><script</quote>, followed by <emphasis>any</emphasis> text, i.e.
6890 it matches the whole page, from the start of the first <script> tag.
6894 That's more than we want, but the pattern continues: <literal>document\.referrer</literal>
6895 matches only the exact string <quote>document.referrer</quote>. The dot needed to
6896 be <emphasis>escaped</emphasis>, i.e. preceded by a backslash, to take away its
6897 special meaning as a joker, and make it just a regular dot. So far, the meaning is:
6898 Match from the start of the first <script> tag in a the page, up to, and including,
6899 the text <quote>document.referrer</quote>, if <emphasis>both</emphasis> are present
6900 in the page (and appear in that order).
6904 But there's still more pattern to go. The next element, again enclosed in parentheses,
6905 is <literal>.*</script></literal>. You already know what <literal>.*</literal>
6906 means, so the whole pattern translates to: Match from the start of the first <script>
6907 tag in a page to the end of the last <script> tag, provided that the text
6908 <quote>document.referrer</quote> appears somewhere in between.
6912 This is still not the whole story, since we have ignored the options and the parentheses:
6913 The portions of the page matched by sub-patterns that are enclosed in parentheses, will be
6914 remembered and be available through the variables <literal>$1, $2, ...</literal> in
6915 the substitute. The <literal>U</literal> option switches to ungreedy matching, which means
6916 that the first <literal>.*</literal> in the pattern will only <quote>eat up</quote> all
6917 text in between <quote><script</quote> and the <emphasis>first</emphasis> occurrence
6918 of <quote>document.referrer</quote>, and that the second <literal>.*</literal> will
6919 only span the text up to the <emphasis>first</emphasis> <quote></script></quote>
6920 tag. Furthermore, the <literal>s</literal> option says that the match may span
6921 multiple lines in the page, and the <literal>g</literal> option again means that the
6922 substitution is global.
6926 So, to summarize, the pattern means: Match all scripts that contain the text
6927 <quote>document.referrer</quote>. Remember the parts of the script from
6928 (and including) the start tag up to (and excluding) the string
6929 <quote>document.referrer</quote> as <literal>$1</literal>, and the part following
6930 that string, up to and including the closing tag, as <literal>$2</literal>.
6934 Now the pattern is deciphered, but wasn't this about substituting things? So
6935 lets look at the substitute: <literal>$1"Not Your Business!"$2</literal> is
6936 easy to read: The text remembered as <literal>$1</literal>, followed by
6937 <literal>"Not Your Business!"</literal> (<emphasis>including</emphasis>
6938 the quotation marks!), followed by the text remembered as <literal>$2</literal>.
6939 This produces an exact copy of the original string, with the middle part
6940 (the <quote>document.referrer</quote>) replaced by <literal>"Not Your
6941 Business!"</literal>.
6945 The whole job now reads: Replace <quote>document.referrer</quote> by
6946 <literal>"Not Your Business!"</literal> wherever it appears inside a
6947 <script> tag. Note that this job won't break JavaScript syntax,
6948 since both the original and the replacement are syntactically valid
6949 string objects. The script just won't have access to the referrer
6950 information anymore.
6954 We'll show you two other jobs from the JavaScript taming department, but
6955 this time only point out the constructs of special interest:
6960 # The status bar is for displaying link targets, not pointless blahblah
6962 s/window\.status\s*=\s*(['"]).*?\1/dUmMy=1/ig</screen>
6966 <literal>\s</literal> stands for whitespace characters (space, tab, newline,
6967 carriage return, form feed), so that <literal>\s*</literal> means: <quote>zero
6968 or more whitespace</quote>. The <literal>?</literal> in <literal>.*?</literal>
6969 makes this matching of arbitrary text ungreedy. (Note that the <literal>U</literal>
6970 option is not set). The <literal>['"]</literal> construct means: <quote>a single
6971 <emphasis>or</emphasis> a double quote</quote>. Finally, <literal>\1</literal> is
6972 a back-reference to the first parenthesis just like <literal>$1</literal> above,
6973 with the difference that in the <emphasis>pattern</emphasis>, a backslash indicates
6974 a back-reference, whereas in the <emphasis>substitute</emphasis>, it's the dollar.
6978 So what does this job do? It replaces assignments of single- or double-quoted
6979 strings to the <quote>window.status</quote> object with a dummy assignment
6980 (using a variable name that is hopefully odd enough not to conflict with
6981 real variables in scripts). Thus, it catches many cases where e.g. pointless
6982 descriptions are displayed in the status bar instead of the link target when
6983 you move your mouse over links.
6988 # Kill OnUnload popups. Yummy. Test: http://www.zdnet.com/zdsubs/yahoo/tree/yfs.html
6990 s/(<body [^>]*)onunload(.*>)/$1never$2/iU</screen>
6995 <ulink url="http://www.w3.org/TR/2000/REC-DOM-Level-2-Events-20001113/events.html#Events-eventgroupings-htmlevents">OnUnload
6996 event binding</ulink> in the HTML DOM was a <emphasis>CRIME</emphasis>.
6997 When I close a browser window, I want it to close and die. Basta.
6998 This job replaces the <quote>onunload</quote> attribute in
6999 <quote><body></quote> tags with the dummy word <literal>never</literal>.
7000 Note that the <literal>i</literal> option makes the pattern matching
7001 case-insensitive. Also note that ungreedy matching alone doesn't always guarantee
7002 a minimal match: In the first parenthesis, we had to use <literal>[^>]*</literal>
7003 instead of <literal>.*</literal> to prevent the match from exceeding the
7004 <body> tag if it doesn't contain <quote>OnUnload</quote>, but the page's
7009 The last example is from the fun department:
7014 FILTER: fun Fun text replacements
7016 # Spice the daily news:
7018 s/microsoft(?!\.com)/MicroSuck/ig</screen>
7022 Note the <literal>(?!\.com)</literal> part (a so-called negative lookahead)
7023 in the job's pattern, which means: Don't match, if the string
7024 <quote>.com</quote> appears directly following <quote>microsoft</quote>
7025 in the page. This prevents links to microsoft.com from being trashed, while
7026 still replacing the word everywhere else.
7031 # Buzzword Bingo (example for extended regex syntax)
7033 s* industry[ -]leading \
7035 | customer[ -]focused \
7036 | market[ -]driven \
7037 | award[ -]winning # Comments are OK, too! \
7038 | high[ -]performance \
7039 | solutions[ -]based \
7043 *<font color="red"><b>BINGO!</b></font> \
7048 The <literal>x</literal> option in this job turns on extended syntax, and allows for
7049 e.g. the liberal use of (non-interpreted!) whitespace for nicer formatting.
7057 <!-- ~~~~~~~~ New section Header ~~~~~~~~~ -->
7059 <sect2 id="predefined-filters"><title>The Pre-defined Filters</title>
7063 Note each filter is also listed in the +filter action section above. Please
7064 keep these listings in sync.
7069 The distribution <filename>default.filter</filename> file contains a selection of
7070 pre-defined filters for your convenience:
7075 <term><emphasis>js-annoyances</emphasis></term>
7078 The purpose of this filter is to get rid of particularly annoying JavaScript abuse.
7083 replaces JavaScript references to the browser's referrer information
7084 with the string "Not Your Business!". This compliments the <literal><link
7085 linkend="hide-referrer">hide-referrer</link></literal> action on the content level.
7090 removes the bindings to the DOM's
7091 <ulink url="http://www.w3.org/TR/2000/REC-DOM-Level-2-Events-20001113/events.html#Events-eventgroupings-htmlevents">unload
7092 event</ulink> which we feel has no right to exist and is responsible for most <quote>exit consoles</quote>, i.e.
7093 nasty windows that pop up when you close another one.
7098 removes code that causes new windows to be opened with undesired properties, such as being
7099 full-screen, non-resizeable, without location, status or menu bar etc.
7105 Use with caution. This is an aggressive filter, and can break sites that
7106 rely heavily on JavaScript.
7112 <term><emphasis>js-events</emphasis></term>
7115 This is a very radical measure. It removes virtually all JavaScript event bindings, which
7116 means that scripts can not react to user actions such as mouse movements or clicks, window
7117 resizing etc, anymore. Use with caution!
7120 We <emphasis>strongly discourage</emphasis> using this filter as a default since it breaks
7121 many legitimate scripts. It is meant for use only on extra-nasty sites (should you really
7128 <term><emphasis>html-annoyances</emphasis></term>
7131 This filter will undo many common instances of HTML based abuse.
7134 The <literal>BLINK</literal> and <literal>MARQUEE</literal> tags
7135 are neutralized (yeah baby!), and browser windows will be created as
7136 resizeable (as of course they should be!), and will have location,
7137 scroll and menu bars -- even if specified otherwise.
7143 <term><emphasis>content-cookies</emphasis></term>
7146 Most cookies are set in the HTTP dialog, where they can be intercepted
7148 <literal><link linkend="crunch-incoming-cookies">crunch-incoming-cookies</link></literal>
7149 and <literal><link linkend="crunch-outgoing-cookies">crunch-outgoing-cookies</link></literal>
7150 actions. But web sites increasingly make use of HTML meta tags and JavaScript
7151 to sneak cookies to the browser on the content level.
7154 This filter disables most HTML and JavaScript code that reads or sets
7155 cookies. It cannot detect all clever uses of these types of code, so it
7156 should not be relied on as an absolute fix. Use it wherever you would also
7157 use the cookie crunch actions.
7163 <term><emphasis>refresh-tags</emphasis></term>
7166 Disable any refresh tags if the interval is greater than nine seconds (so
7167 that redirections done via refresh tags are not destroyed). This is useful
7168 for dial-on-demand setups, or for those who find this HTML feature
7175 <term><emphasis>unsolicited-popups</emphasis></term>
7178 This filter attempts to prevent only <quote>unsolicited</quote> pop-up
7179 windows from opening, yet still allow pop-up windows that the user
7180 has explicitly chosen to open. It was added in version 3.0.1,
7181 as an improvement over earlier such filters.
7184 Technical note: The filter works by redefining the window.open JavaScript
7185 function to a dummy function, <literal>PrivoxyWindowOpen()</literal>,
7186 during the loading and rendering phase of each HTML page access, and
7187 restoring the function afterward.
7190 This is recommended only for browsers that cannot perform this function
7191 reliably themselves. And be aware that some sites require such windows
7192 in order to function normally. Use with caution.
7198 <term><emphasis>all-popups</emphasis></term>
7201 Attempt to prevent <emphasis>all</emphasis> pop-up windows from opening.
7202 Note this should be used with even more discretion than the above, since
7203 it is more likely to break some sites that require pop-ups for normal
7204 usage. Use with caution.
7210 <term><emphasis>img-reorder</emphasis></term>
7213 This is a helper filter that has no value if used alone. It makes the
7214 <literal>banners-by-size</literal> and <literal>banners-by-link</literal>
7215 (see below) filters more effective and should be enabled together with them.
7221 <term><emphasis>banners-by-size</emphasis></term>
7224 This filter removes image tags purely based on what size they are. Fortunately
7225 for us, many ads and banner images tend to conform to certain standardized
7226 sizes, which makes this filter quite effective for ad stripping purposes.
7229 Occasionally this filter will cause false positives on images that are not ads,
7230 but just happen to be of one of the standard banner sizes.
7233 Recommended only for those who require extreme ad blocking. The default
7234 block rules should catch 95+% of all ads <emphasis>without</emphasis> this filter enabled.
7240 <term><emphasis>banners-by-link</emphasis></term>
7243 This is an experimental filter that attempts to kill any banners if
7244 their URLs seem to point to known or suspected click trackers. It is currently
7245 not of much value and is not recommended for use by default.
7251 <term><emphasis>webbugs</emphasis></term>
7254 Webbugs are small, invisible images (technically 1X1 GIF images), that
7255 are used to track users across websites, and collect information on them.
7256 As an HTML page is loaded by the browser, an embedded image tag causes the
7257 browser to contact a third-party site, disclosing the tracking information
7258 through the requested URL and/or cookies for that third-party domain, without
7259 the user ever becoming aware of the interaction with the third-party site.
7260 HTML-ized spam also uses a similar technique to verify email addresses.
7263 This filter removes the HTML code that loads such <quote>webbugs</quote>.
7269 <term><emphasis>tiny-textforms</emphasis></term>
7272 A rather special-purpose filter that can be used to enlarge textareas (those
7273 multi-line text boxes in web forms) and turn off hard word wrap in them.
7274 It was written for the sourceforge.net tracker system where such boxes are
7275 a nuisance, but it can be handy on other sites, too.
7278 It is not recommended to use this filter as a default.
7284 <term><emphasis>jumping-windows</emphasis></term>
7287 Many consider windows that move, or resize themselves to be abusive. This filter
7288 neutralizes the related JavaScript code. Note that some sites might not display
7289 or behave as intended when using this filter. Use with caution.
7295 <term><emphasis>frameset-borders</emphasis></term>
7298 Some web designers seem to assume that everyone in the world will view their
7299 web sites using the same browser brand and version, screen resolution etc,
7300 because only that assumption could explain why they'd use static frame sizes,
7301 yet prevent their frames from being resized by the user, should they be too
7302 small to show their whole content.
7305 This filter removes the related HTML code. It should only be applied to sites
7312 <term><emphasis>demoronizer</emphasis></term>
7315 Many Microsoft products that generate HTML use non-standard extensions (read:
7316 violations) of the ISO 8859-1 aka Latin-1 character set. This can cause those
7317 HTML documents to display with errors on standard-compliant platforms.
7320 This filter translates the MS-only characters into Latin-1 equivalents.
7321 It is not necessary when using MS products, and will cause corruption of
7322 all documents that use 8-bit character sets other than Latin-1. It's mostly
7323 worthwhile for Europeans on non-MS platforms, if weird garbage characters
7324 sometimes appear on some pages, or user agents that don't correct for this on
7327 My version of Mozilla (ancient) shows litte square boxes for quote
7328 characters, and apostrophes on moronized pages. So many pages have this, I
7329 can read them fine now. HB 08/27/06
7336 <term><emphasis>shockwave-flash</emphasis></term>
7339 A filter for shockwave haters. As the name suggests, this filter strips code
7340 out of web pages that is used to embed shockwave flash objects.
7348 <term><emphasis>quicktime-kioskmode</emphasis></term>
7351 Change HTML code that embeds Quicktime objects so that kioskmode, which
7352 prevents saving, is disabled.
7358 <term><emphasis>fun</emphasis></term>
7361 Text replacements for subversive browsing fun. Make fun of your favorite
7362 Monopolist or play buzzword bingo.
7368 <term><emphasis>crude-parental</emphasis></term>
7371 A demonstration-only filter that shows how <application>Privoxy</application>
7372 can be used to delete web content on a keyword basis.
7378 <term><emphasis>ie-exploits</emphasis></term>
7381 An experimental collection of text replacements to disable malicious HTML and JavaScript
7382 code that exploits known security holes in Internet Explorer.
7385 Presently, it only protects against Nimda and a cross-site scripting bug, and
7386 would need active maintenance to provide more substantial protection.
7392 <term><emphasis>site-specifics</emphasis></term>
7395 Some web sites have very specific problems, the cure for which doesn't apply
7396 anywhere else, or could even cause damage on other sites.
7399 This is a collection of such site-specific cures which should only be applied
7400 to the sites they were intended for, which is what the supplied
7401 <filename>default.action</filename> file does. Users shouldn't need to change
7402 anything regarding this filter.
7408 <term><emphasis>google</emphasis></term>
7411 A CSS based block for Google text ads. Also removes a width limitation
7412 and the toolbar advertisement.
7418 <term><emphasis>yahoo</emphasis></term>
7421 Another CSS based block, this time for Yahoo text ads. And removes
7422 a width limitation as well.
7428 <term><emphasis>msn</emphasis></term>
7431 Another CSS based block, this time for MSN text ads. And removes
7432 tracking URLs, as well as a width limitation.
7438 <term><emphasis>blogspot</emphasis></term>
7441 Cleans up some Blogspot blogs. Read the fine print before using this one!
7444 This filter also intentionally removes some navigation stuff and sets the
7445 page width to 100%. As a result, some rounded <quote>corners</quote> would
7446 appear to early or not at all and as fixing this would require a browser
7447 that understands background-size (CSS3), they are removed instead.
7453 <term><emphasis>xml-to-html</emphasis></term>
7456 Server-header filter to change the Content-Type from xml to html.
7462 <term><emphasis>html-to-xml</emphasis></term>
7465 Server-header filter to change the Content-Type from html to xml.
7471 <term><emphasis>no-ping</emphasis></term>
7474 Removes the non-standard <literal>ping</literal> attribute from
7475 anchor and area HTML tags.
7481 <term><emphasis>hide-tor-exit-notation</emphasis></term>
7484 Client-header filter to remove the <command>Tor</command> exit node notation
7485 found in Host and Referer headers.
7488 If &my-app; and <command>Tor</command> are chained and &my-app;
7489 is configured to use socks4a, one can use <quote>http://www.example.org.foobar.exit/</quote>
7490 to access the host <quote>www.example.org</quote> through the
7491 <command>Tor</command> exit node <quote>foobar</quote>.
7494 As the HTTP client isn't aware of this notation, it treats the
7495 whole string <quote>www.example.org.foobar.exit</quote> as host and uses it
7496 for the <quote>Host</quote> and <quote>Referer</quote> headers. From the
7497 server's point of view the resulting headers are invalid and can cause problems.
7500 An invalid <quote>Referer</quote> header can trigger <quote>hot-linking</quote>
7501 protections, an invalid <quote>Host</quote> header will make it impossible for
7502 the server to find the right vhost (several domains hosted on the same IP address).
7505 This client-header filter removes the <quote>foo.exit</quote> part in those headers
7506 to prevent the mentioned problems. Note that it only modifies
7507 the HTTP headers, it doesn't make it impossible for the server
7508 to detect your <command>Tor</command> exit node based on the IP address
7509 the request is coming from.
7516 <term><emphasis> </emphasis></term>
7529 <!-- ~~~~~~~~ New section Header ~~~~~~~~~ -->
7530 <sect2 id="external-filter-syntax"><title>External filter syntax</title>
7532 External filters are scripts or programs that can modify the content in
7533 case common <literal><link linkend="filter">filters</link></literal>
7534 aren't powerful enough.
7537 External filters can be written in any language the platform &my-app; runs
7541 They are controlled with the
7542 <literal><link linkend="external-filter">external-filter</link></literal> action
7543 and have to be defined in the <literal><link linkend="filterfile">filterfile</link></literal>
7547 The header looks like any other filter, but instead of pcrs jobs, external
7548 filters contain a single job which can be a program or a shell script (which
7549 may call other scripts or programs).
7552 External filters read the content from STDIN and write the rewritten
7554 The environment variables PRIVOXY_URL, PRIVOXY_PATH, PRIVOXY_HOST,
7555 PRIVOXY_ORIGIN, PRIVOXY_LISTEN_ADDRESS can be used to get some details
7556 about the client request.
7559 &my-app; will temporary store the content to filter in the
7560 <literal><link linkend="temporary-directory">temporary-directory</link></literal>.
7564 EXTERNAL-FILTER: cat Pointless example filter that doesn't actually modify the content
7567 # Incorrect reimplementation of the filter above in POSIX shell.
7569 # Note that it's a single job that spans multiple lines, the line
7570 # breaks are not passed to the shell, thus the semicolons are required.
7572 # If the script isn't trivial, it is recommended to put it into an external file.
7574 # In general, writing external filters entirely in POSIX shell is not
7575 # considered a good idea.
7576 EXTERNAL-FILTER: cat2 Pointless example filter that despite its name may actually modify the content
7582 EXTERNAL-FILTER: rotate-image Rotate an image by 180 degree. Test filter with limited value.
7583 /usr/local/bin/convert - -rotate 180 -
7585 EXTERNAL-FILTER: citation-needed Adds a "[citation needed]" tag to an image. The coordinates may need adjustment.
7586 /usr/local/bin/convert - -pointsize 16 -fill white -annotate +17+418 "[citation needed]" -
7592 Currently external filters are executed with &my-app;'s privileges!
7593 Only use external filters you understand and trust.
7597 External filters are experimental and the syntax may change in the future.
7603 <!-- ~ End section ~ -->
7607 <!-- ~~~~~ New section ~~~~~ -->
7609 <sect1 id="templates">
7610 <title>Privoxy's Template Files</title>
7612 All <application>Privoxy</application> built-in pages, i.e. error pages such as the
7613 <ulink url="http://show-the-404-error.page"><quote>404 - No Such Domain</quote>
7614 error page</ulink>, the <ulink
7615 url="http://ads.bannerserver.example.com/nasty-ads/sponsor.html"><quote>BLOCKED</quote>
7617 and all pages of its <ulink url="http://config.privoxy.org/">web-based
7618 user interface</ulink>, are generated from <emphasis>templates</emphasis>.
7619 (<application>Privoxy</application> must be running for the above links to work as
7624 These templates are stored in a subdirectory of the <link linkend="confdir">configuration
7625 directory</link> called <filename>templates</filename>. On Unixish platforms,
7627 <ulink url="file:///etc/privoxy/templates/"><filename>/etc/privoxy/templates/</filename></ulink>.
7631 The templates are basically normal HTML files, but with place-holders (called symbols
7632 or exports), which <application>Privoxy</application> fills at run time. It
7633 is possible to edit the templates with a normal text editor, should you want
7634 to customize them. (<emphasis>Not recommended for the casual
7635 user</emphasis>). Should you create your own custom templates, you should use
7636 the <filename>config</filename> setting <link linkend="templdir">templdir</link>
7637 to specify an alternate location, so your templates do not get overwritten
7641 Note that just like in configuration files, lines starting
7642 with <literal>#</literal> are ignored when the templates are filled in.
7646 The place-holders are of the form <literal>@name@</literal>, and you will
7647 find a list of available symbols, which vary from template to template,
7648 in the comments at the start of each file. Note that these comments are not
7649 always accurate, and that it's probably best to look at the existing HTML
7650 code to find out which symbols are supported and what they are filled in with.
7654 A special application of this substitution mechanism is to make whole
7655 blocks of HTML code disappear when a specific symbol is set. We use this
7656 for many purposes, one of them being to include the beta warning in all
7657 our user interface (CGI) pages when <application>Privoxy</application>
7658 is in an alpha or beta development stage:
7663 <!-- @if-unstable-start -->
7665 ... beta warning HTML code goes here ...
7667 <!-- if-unstable-end@ --></screen>
7671 If the "unstable" symbol is set, everything in between and including
7672 <literal>@if-unstable-start</literal> and <literal>if-unstable-end@</literal>
7673 will disappear, leaving nothing but an empty comment:
7677 <screen><!-- --></screen>
7681 There's also an if-then-else construct and an <literal>#include</literal>
7682 mechanism, but you'll sure find out if you are inclined to edit the
7687 All templates refer to a style located at
7688 <ulink url="http://config.privoxy.org/send-stylesheet"><literal>http://config.privoxy.org/send-stylesheet</literal></ulink>.
7689 This is, of course, locally served by <application>Privoxy</application>
7690 and the source for it can be found and edited in the
7691 <filename>cgi-style.css</filename> template.
7696 <!-- ~ End section ~ -->
7700 <!-- ~~~~~ New section ~~~~~ -->
7702 <sect1 id="contact"><title>Contacting the Developers, Bug Reporting and Feature
7705 <!-- Include contacting.sgml boilerplate: -->
7707 <!-- end boilerplate -->
7711 <!-- ~ End section ~ -->
7714 <!-- ~~~~~ New section ~~~~~ -->
7715 <sect1 id="copyright"><title>Privoxy Copyright, License and History</title>
7717 <!-- Include copyright.sgml: -->
7719 <!-- end copyright -->
7722 <application>Privoxy</application> is free software; you can
7723 redistribute it and/or modify it under the terms of the
7724 <citetitle>GNU General Public License</citetitle>, version 2,
7725 as published by the Free Software Foundation and included in
7729 <!-- ~~~~~ New section ~~~~~ -->
7730 <sect2 id="license"><title>License</title>
7732 <screen><![ RCDATA [ &GPLv2; ]]></screen>
7736 <!-- ~ End section ~ -->
7739 <!-- ~~~~~ New section ~~~~~ -->
7741 <sect2 id="history"><title>History</title>
7742 <!-- Include history.sgml: -->
7744 <!-- end history -->
7747 <sect2 id="authors"><title>Authors</title>
7748 <!-- Include p-authors.sgml: -->
7750 <!-- end authors -->
7755 <!-- ~ End section ~ -->
7758 <!-- ~~~~~ New section ~~~~~ -->
7759 <sect1 id="seealso"><title>See Also</title>
7760 <!-- Include seealso.sgml: -->
7762 <!-- end seealso -->
7767 <!-- ~~~~~ New section ~~~~~ -->
7768 <sect1 id="appendix"><title>Appendix</title>
7771 <!-- ~~~~~ New section ~~~~~ -->
7773 <title>Regular Expressions</title>
7775 <application>Privoxy</application> uses Perl-style <quote>regular
7776 expressions</quote> in its <link linkend="actions-file">actions
7777 files</link> and <link linkend="filter-file">filter file</link>,
7778 through the <ulink url="http://www.pcre.org/">PCRE</ulink> and
7781 <ulink url="http://www.oesterhelt.org/pcrs/">PCRS</ulink> libraries.
7783 <application>PCRS</application> libraries.
7787 If you are reading this, you probably don't understand what <quote>regular
7788 expressions</quote> are, or what they can do. So this will be a very brief
7789 introduction only. A full explanation would require a <ulink
7790 url="http://www.oreilly.com/catalog/regex/">book</ulink> ;-)
7794 Regular expressions provide a language to describe patterns that can be
7795 run against strings of characters (letter, numbers, etc), to see if they
7796 match the string or not. The patterns are themselves (sometimes complex)
7797 strings of literal characters, combined with wild-cards, and other special
7798 characters, called meta-characters. The <quote>meta-characters</quote> have
7799 special meanings and are used to build complex patterns to be matched against.
7800 Perl Compatible Regular Expressions are an especially convenient
7801 <quote>dialect</quote> of the regular expression language.
7805 To make a simple analogy, we do something similar when we use wild-card
7806 characters when listing files with the <command>dir</command> command in DOS.
7807 <literal>*.*</literal> matches all filenames. The <quote>special</quote>
7808 character here is the asterisk which matches any and all characters. We can be
7809 more specific and use <literal>?</literal> to match just individual
7810 characters. So <quote>dir file?.text</quote> would match
7811 <quote>file1.txt</quote>, <quote>file2.txt</quote>, etc. We are pattern
7812 matching, using a similar technique to <quote>regular expressions</quote>!
7816 Regular expressions do essentially the same thing, but are much, much more
7817 powerful. There are many more <quote>special characters</quote> and ways of
7818 building complex patterns however. Let's look at a few of the common ones,
7819 and then some examples:
7824 <emphasis>.</emphasis> - Matches any single character, e.g. <quote>a</quote>,
7825 <quote>A</quote>, <quote>4</quote>, <quote>:</quote>, or <quote>@</quote>.
7827 </simplelist></para>
7831 <emphasis>?</emphasis> - The preceding character or expression is matched ZERO or ONE
7834 </simplelist></para>
7838 <emphasis>+</emphasis> - The preceding character or expression is matched ONE or MORE
7841 </simplelist></para>
7845 <emphasis>*</emphasis> - The preceding character or expression is matched ZERO or MORE
7848 </simplelist></para>
7852 <emphasis>\</emphasis> - The <quote>escape</quote> character denotes that
7853 the following character should be taken literally. This is used where one of the
7854 special characters (e.g. <quote>.</quote>) needs to be taken literally and
7855 not as a special meta-character. Example: <quote>example\.com</quote>, makes
7856 sure the period is recognized only as a period (and not expanded to its
7857 meta-character meaning of any single character).
7859 </simplelist></para>
7863 <emphasis>[ ]</emphasis> - Characters enclosed in brackets will be matched if
7864 any of the enclosed characters are encountered. For instance, <quote>[0-9]</quote>
7865 matches any numeric digit (zero through nine). As an example, we can combine
7866 this with <quote>+</quote> to match any digit one of more times: <quote>[0-9]+</quote>.
7868 </simplelist></para>
7872 <emphasis>( )</emphasis> - parentheses are used to group a sub-expression,
7873 or multiple sub-expressions.
7875 </simplelist></para>
7879 <emphasis>|</emphasis> - The <quote>bar</quote> character works like an
7880 <quote>or</quote> conditional statement. A match is successful if the
7881 sub-expression on either side of <quote>|</quote> matches. As an example:
7882 <quote>/(this|that) example/</quote> uses grouping and the bar character
7883 and would match either <quote>this example</quote> or <quote>that
7884 example</quote>, and nothing else.
7886 </simplelist></para>
7889 These are just some of the ones you are likely to use when matching URLs with
7890 <application>Privoxy</application>, and is a long way from a definitive
7891 list. This is enough to get us started with a few simple examples which may
7892 be more illuminating:
7896 <emphasis><literal>/.*/banners/.*</literal></emphasis> - A simple example
7897 that uses the common combination of <quote>.</quote> and <quote>*</quote> to
7898 denote any character, zero or more times. In other words, any string at all.
7899 So we start with a literal forward slash, then our regular expression pattern
7900 (<quote>.*</quote>) another literal forward slash, the string
7901 <quote>banners</quote>, another forward slash, and lastly another
7902 <quote>.*</quote>. We are building
7903 a directory path here. This will match any file with the path that has a
7904 directory named <quote>banners</quote> in it. The <quote>.*</quote> matches
7905 any characters, and this could conceivably be more forward slashes, so it
7906 might expand into a much longer looking path. For example, this could match:
7907 <quote>/eye/hate/spammers/banners/annoy_me_please.gif</quote>, or just
7908 <quote>/banners/annoying.html</quote>, or almost an infinite number of other
7909 possible combinations, just so it has <quote>banners</quote> in the path
7914 And now something a little more complex:
7918 <emphasis><literal>/.*/adv((er)?ts?|ertis(ing|ements?))?/</literal></emphasis> -
7919 We have several literal forward slashes again (<quote>/</quote>), so we are
7920 building another expression that is a file path statement. We have another
7921 <quote>.*</quote>, so we are matching against any conceivable sub-path, just so
7922 it matches our expression. The only true literal that <emphasis>must
7923 match</emphasis> our pattern is <application>adv</application>, together with
7924 the forward slashes. What comes after the <quote>adv</quote> string is the
7929 Remember the <quote>?</quote> means the preceding expression (either a
7930 literal character or anything grouped with <quote>(...)</quote> in this case)
7931 can exist or not, since this means either zero or one match. So
7932 <quote>((er)?ts?|ertis(ing|ements?))</quote> is optional, as are the
7933 individual sub-expressions: <quote>(er)</quote>,
7934 <quote>(ing|ements?)</quote>, and the <quote>s</quote>. The <quote>|</quote>
7935 means <quote>or</quote>. We have two of those. For instance,
7936 <quote>(ing|ements?)</quote>, can expand to match either <quote>ing</quote>
7937 <emphasis>OR</emphasis> <quote>ements?</quote>. What is being done here, is an
7938 attempt at matching as many variations of <quote>advertisement</quote>, and
7939 similar, as possible. So this would expand to match just <quote>adv</quote>,
7940 or <quote>advert</quote>, or <quote>adverts</quote>, or
7941 <quote>advertising</quote>, or <quote>advertisement</quote>, or
7942 <quote>advertisements</quote>. You get the idea. But it would not match
7943 <quote>advertizements</quote> (with a <quote>z</quote>). We could fix that by
7944 changing our regular expression to:
7945 <quote>/.*/adv((er)?ts?|erti(s|z)(ing|ements?))?/</quote>, which would then match
7950 <emphasis><literal>/.*/advert[0-9]+\.(gif|jpe?g)</literal></emphasis> - Again
7951 another path statement with forward slashes. Anything in the square brackets
7952 <quote>[ ]</quote> can be matched. This is using <quote>0-9</quote> as a
7953 shorthand expression to mean any digit one through nine. It is the same as
7954 saying <quote>0123456789</quote>. So any digit matches. The <quote>+</quote>
7955 means one or more of the preceding expression must be included. The preceding
7956 expression here is what is in the square brackets -- in this case, any digit
7957 one through nine. Then, at the end, we have a grouping: <quote>(gif|jpe?g)</quote>.
7958 This includes a <quote>|</quote>, so this needs to match the expression on
7959 either side of that bar character also. A simple <quote>gif</quote> on one side, and the other
7960 side will in turn match either <quote>jpeg</quote> or <quote>jpg</quote>,
7961 since the <quote>?</quote> means the letter <quote>e</quote> is optional and
7962 can be matched once or not at all. So we are building an expression here to
7963 match image GIF or JPEG type image file. It must include the literal
7964 string <quote>advert</quote>, then one or more digits, and a <quote>.</quote>
7965 (which is now a literal, and not a special character, since it is escaped
7966 with <quote>\</quote>), and lastly either <quote>gif</quote>, or
7967 <quote>jpeg</quote>, or <quote>jpg</quote>. Some possible matches would
7968 include: <quote>//advert1.jpg</quote>,
7969 <quote>/nasty/ads/advert1234.gif</quote>,
7970 <quote>/banners/from/hell/advert99.jpg</quote>. It would not match
7971 <quote>advert1.gif</quote> (no leading slash), or
7972 <quote>/adverts232.jpg</quote> (the expression does not include an
7973 <quote>s</quote>), or <quote>/advert1.jsp</quote> (<quote>jsp</quote> is not
7974 in the expression anywhere).
7978 We are barely scratching the surface of regular expressions here so that you
7979 can understand the default <application>Privoxy</application>
7980 configuration files, and maybe use this knowledge to customize your own
7981 installation. There is much, much more that can be done with regular
7982 expressions. Now that you know enough to get started, you can learn more on
7987 More reading on Perl Compatible Regular expressions:
7988 <ulink url="http://perldoc.perl.org/perlre.html">http://perldoc.perl.org/perlre.html</ulink>
7992 For information on regular expression based substitutions and their applications
7993 in filters, please see the <link linkend="filter-file">filter file tutorial</link>
7998 <!-- ~ End section ~ -->
8001 <!-- ~~~~~ New section ~~~~~ -->
8002 <sect2 id="internal-pages">
8003 <title>Privoxy's Internal Pages</title>
8006 Since <application>Privoxy</application> proxies each requested
8007 web page, it is easy for <application>Privoxy</application> to
8008 trap certain special URLs. In this way, we can talk directly to
8009 <application>Privoxy</application>, and see how it is
8010 configured, see how our rules are being applied, change these
8011 rules and other configuration options, and even turn
8012 <application>Privoxy's</application> filtering off, all with
8018 The URLs listed below are the special ones that allow direct access
8019 to <application>Privoxy</application>. Of course,
8020 <application>Privoxy</application> must be running to access these. If
8021 not, you will get a friendly error message. Internet access is not
8034 <ulink url="http://config.privoxy.org/">http://config.privoxy.org/</ulink>
8038 There is a shortcut: <ulink url="http://p.p/">http://p.p/</ulink> (But it
8039 doesn't provide a fall-back to a real page, in case the request is not
8040 sent through <application>Privoxy</application>)
8046 Show information about the current configuration, including viewing and
8047 editing of actions files:
8051 <ulink url="http://config.privoxy.org/show-status">http://config.privoxy.org/show-status</ulink>
8058 Show the source code version numbers:
8062 <ulink url="http://config.privoxy.org/show-version">http://config.privoxy.org/show-version</ulink>
8069 Show the browser's request headers:
8073 <ulink url="http://config.privoxy.org/show-request">http://config.privoxy.org/show-request</ulink>
8080 Show which actions apply to a URL and why:
8084 <ulink url="http://config.privoxy.org/show-url-info">http://config.privoxy.org/show-url-info</ulink>
8091 Toggle Privoxy on or off. This feature can be turned off/on in the main
8092 <filename>config</filename> file. When toggled <quote>off</quote>, <quote>Privoxy</quote>
8093 continues to run, but only as a pass-through proxy, with no actions taking
8098 <ulink url="http://config.privoxy.org/toggle">http://config.privoxy.org/toggle</ulink>
8102 Short cuts. Turn off, then on:
8106 <ulink url="http://config.privoxy.org/toggle?set=disable">http://config.privoxy.org/toggle?set=disable</ulink>
8111 <ulink url="http://config.privoxy.org/toggle?set=enable">http://config.privoxy.org/toggle?set=enable</ulink>
8122 <!-- ~~~~~ New section ~~~~~ -->
8124 <title>Chain of Events</title>
8126 Let's take a quick look at how some of <application>Privoxy's</application>
8127 core features are triggered, and the ensuing sequence of events when a web
8128 page is requested by your browser:
8135 First, your web browser requests a web page. The browser knows to send
8136 the request to <application>Privoxy</application>, which will in turn,
8137 relay the request to the remote web server after passing the following
8143 <application>Privoxy</application> traps any request for its own internal CGI
8144 pages (e.g <ulink url="http://p.p/">http://p.p/</ulink>) and sends the CGI page back to the browser.
8149 Next, <application>Privoxy</application> checks to see if the URL
8151 linkend="BLOCK"><quote>+block</quote></link> patterns. If
8152 so, the URL is then blocked, and the remote web server will not be contacted.
8153 <link linkend="HANDLE-AS-IMAGE"><quote>+handle-as-image</quote></link>
8155 <link linkend="HANDLE-AS-EMPTY-DOCUMENT"><quote>+handle-as-empty-document</quote></link>
8156 are then checked, and if there is no match, an
8157 HTML <quote>BLOCKED</quote> page is sent back to the browser. Otherwise, if
8158 it does match, an image is returned for the former, and an empty text
8159 document for the latter. The type of image would depend on the setting of
8160 <link linkend="SET-IMAGE-BLOCKER"><quote>+set-image-blocker</quote></link>
8161 (blank, checkerboard pattern, or an HTTP redirect to an image elsewhere).
8166 Untrusted URLs are blocked. If URLs are being added to the
8167 <filename>trust</filename> file, then that is done.
8172 If the URL pattern matches the <link
8173 linkend="FAST-REDIRECTS"><quote>+fast-redirects</quote></link> action,
8174 it is then processed. Unwanted parts of the requested URL are stripped.
8179 Now the rest of the client browser's request headers are processed. If any
8180 of these match any of the relevant actions (e.g. <link
8181 linkend="HIDE-USER-AGENT"><quote>+hide-user-agent</quote></link>,
8182 etc.), headers are suppressed or forged as determined by these actions and
8188 Now the web server starts sending its response back (i.e. typically a web
8194 First, the server headers are read and processed to determine, among other
8195 things, the MIME type (document type) and encoding. The headers are then
8196 filtered as determined by the
8197 <link linkend="CRUNCH-INCOMING-COOKIES"><quote>+crunch-incoming-cookies</quote></link>,
8198 <link linkend="SESSION-COOKIES-ONLY"><quote>+session-cookies-only</quote></link>,
8199 and <link linkend="DOWNGRADE-HTTP-VERSION"><quote>+downgrade-http-version</quote></link>
8205 If any <link linkend="FILTER"><quote>+filter</quote></link> action
8207 linkend="DEANIMATE-GIFS"><quote>+deanimate-gifs</quote></link>
8208 action applies (and the document type fits the action), the rest of the page is
8209 read into memory (up to a configurable limit). Then the filter rules (from
8210 <filename>default.filter</filename> and any other filter files) are
8211 processed against the buffered content. Filters are applied in the order
8212 they are specified in one of the filter files. Animated GIFs, if present,
8213 are reduced to either the first or last frame, depending on the action
8214 setting.The entire page, which is now filtered, is then sent by
8215 <application>Privoxy</application> back to your browser.
8218 If neither a <link linkend="FILTER"><quote>+filter</quote></link> action
8220 linkend="DEANIMATE-GIFS"><quote>+deanimate-gifs</quote></link>
8221 matches, then <application>Privoxy</application> passes the raw data through
8222 to the client browser as it becomes available.
8227 As the browser receives the now (possibly filtered) page content, it
8228 reads and then requests any URLs that may be embedded within the page
8229 source, e.g. ad images, stylesheets, JavaScript, other HTML documents (e.g.
8230 frames), sounds, etc. For each of these objects, the browser issues a
8231 separate request (this is easily viewable in <application>Privoxy's</application>
8232 logs). And each such request is in turn processed just as above. Note that a
8233 complex web page will have many, many such embedded URLs. If these
8234 secondary requests are to a different server, then quite possibly a very
8235 differing set of actions is triggered.
8242 NOTE: This is somewhat of a simplistic overview of what happens with each URL
8243 request. For the sake of brevity and simplicity, we have focused on
8244 <application>Privoxy's</application> core features only.
8250 <!-- ~~~~~ New section ~~~~~ -->
8251 <sect2 id="actionsanat">
8252 <title>Troubleshooting: Anatomy of an Action</title>
8255 The way <application>Privoxy</application> applies
8256 <link linkend="ACTIONS">actions</link> and <link linkend="FILTER">filters</link>
8257 to any given URL can be complex, and not always so
8258 easy to understand what is happening. And sometimes we need to be able to
8259 <emphasis>see</emphasis> just what <application>Privoxy</application> is
8260 doing. Especially, if something <application>Privoxy</application> is doing
8261 is causing us a problem inadvertently. It can be a little daunting to look at
8262 the actions and filters files themselves, since they tend to be filled with
8263 <link linkend="regex">regular expressions</link> whose consequences are not
8268 One quick test to see if <application>Privoxy</application> is causing a problem
8269 or not, is to disable it temporarily. This should be the first troubleshooting
8270 step (be sure to flush caches afterward!). Looking at the
8271 logs is a good idea too. (Note that both the toggle feature and logging are
8272 enabled via <filename>config</filename> file settings, and may need to be
8273 turned <quote>on</quote>.)
8276 Another easy troubleshooting step to try is if you have done any
8277 customization of your installation, revert back to the installed
8278 defaults and see if that helps. There are times the developers get complaints
8279 about one thing or another, and the problem is more related to a customized
8280 configuration issue.
8284 <application>Privoxy</application> also provides the
8285 <ulink url="http://config.privoxy.org/show-url-info">http://config.privoxy.org/show-url-info</ulink>
8286 page that can show us very specifically how <application>actions</application>
8287 are being applied to any given URL. This is a big help for troubleshooting.
8291 First, enter one URL (or partial URL) at the prompt, and then
8292 <application>Privoxy</application> will tell us
8293 how the current configuration will handle it. This will not
8294 help with filtering effects (i.e. the <link
8295 linkend="FILTER"><quote>+filter</quote></link> action) from
8296 one of the filter files since this is handled very
8297 differently and not so easy to trap! It also will not tell you about any other
8298 URLs that may be embedded within the URL you are testing. For instance, images
8299 such as ads are expressed as URLs within the raw page source of HTML pages. So
8300 you will only get info for the actual URL that is pasted into the prompt area
8301 -- not any sub-URLs. If you want to know about embedded URLs like ads, you
8302 will have to dig those out of the HTML source. Use your browser's <quote>View
8303 Page Source</quote> option for this. Or right click on the ad, and grab the
8308 Let's try an example, <ulink url="http://google.com">google.com</ulink>,
8309 and look at it one section at a time in a sample configuration (your real
8310 configuration may vary):
8315 Matches for http://www.google.com:
8317 In file: default.action <guibutton>[ View ]</guibutton> <guibutton>[ Edit ]</guibutton>
8319 {+change-x-forwarded-for{block}
8320 +deanimate-gifs {last}
8321 +fast-redirects {check-decoded-url}
8322 +filter {refresh-tags}
8323 +filter {img-reorder}
8324 +filter {banners-by-size}
8326 +filter {jumping-windows}
8327 +filter {ie-exploits}
8328 +hide-from-header {block}
8329 +hide-referrer {forge}
8330 +session-cookies-only
8331 +set-image-blocker {pattern}
8334 { -session-cookies-only }
8340 In file: user.action <guibutton>[ View ]</guibutton> <guibutton>[ Edit ]</guibutton>
8341 (no matches in this file)
8346 This is telling us how we have defined our
8347 <link linkend="ACTIONS"><quote>actions</quote></link>, and
8348 which ones match for our test case, <quote>google.com</quote>.
8349 Displayed is all the actions that are available to us. Remember,
8350 the <literal>+</literal> sign denotes <quote>on</quote>. <literal>-</literal>
8351 denotes <quote>off</quote>. So some are <quote>on</quote> here, but many
8352 are <quote>off</quote>. Each example we try may provide a slightly different
8353 end result, depending on our configuration directives.
8357 is for our <filename>default.action</filename> file. The large, multi-line
8358 listing, is how the actions are set to match for all URLs, i.e. our default
8359 settings. If you look at your <quote>actions</quote> file, this would be the
8360 section just below the <quote>aliases</quote> section near the top. This
8361 will apply to all URLs as signified by the single forward slash at the end
8362 of the listing -- <quote> / </quote>.
8366 But we have defined additional actions that would be exceptions to these general
8367 rules, and then we list specific URLs (or patterns) that these exceptions
8368 would apply to. Last match wins. Just below this then are two explicit
8369 matches for <quote>.google.com</quote>. The first is negating our previous
8370 cookie setting, which was for <link
8371 linkend="SESSION-COOKIES-ONLY"><quote>+session-cookies-only</quote></link>
8372 (i.e. not persistent). So we will allow persistent cookies for google, at
8373 least that is how it is in this example. The second turns
8374 <emphasis>off</emphasis> any <link
8375 linkend="FAST-REDIRECTS"><quote>+fast-redirects</quote></link>
8376 action, allowing this to take place unmolested. Note that there is a leading
8377 dot here -- <quote>.google.com</quote>. This will match any hosts and
8378 sub-domains, in the google.com domain also, such as
8379 <quote>www.google.com</quote> or <quote>mail.google.com</quote>. But it would not
8380 match <quote>www.google.de</quote>! So, apparently, we have these two actions
8381 defined as exceptions to the general rules at the top somewhere in the lower
8382 part of our <filename>default.action</filename> file, and
8383 <quote>google.com</quote> is referenced somewhere in these latter sections.
8387 Then, for our <filename>user.action</filename> file, we again have no hits.
8388 So there is nothing google-specific that we might have added to our own, local
8389 configuration. If there was, those actions would over-rule any actions from
8390 previously processed files, such as <filename>default.action</filename>.
8391 <filename>user.action</filename> typically has the last word. This is the
8392 best place to put hard and fast exceptions,
8396 And finally we pull it all together in the bottom section and summarize how
8397 <application>Privoxy</application> is applying all its <quote>actions</quote>
8398 to <quote>google.com</quote>:
8409 +change-x-forwarded-for{block}
8410 -client-header-filter{hide-tor-exit-notation}
8411 -content-type-overwrite
8412 -crunch-client-header
8413 -crunch-if-none-match
8414 -crunch-incoming-cookies
8415 -crunch-outgoing-cookies
8416 -crunch-server-header
8417 +deanimate-gifs {last}
8418 -downgrade-http-version
8421 -filter {content-cookies}
8422 -filter {all-popups}
8423 -filter {banners-by-link}
8424 -filter {tiny-textforms}
8425 -filter {frameset-borders}
8426 -filter {demoronizer}
8427 -filter {shockwave-flash}
8428 -filter {quicktime-kioskmode}
8430 -filter {crude-parental}
8431 -filter {site-specifics}
8432 -filter {js-annoyances}
8433 -filter {html-annoyances}
8434 +filter {refresh-tags}
8435 -filter {unsolicited-popups}
8436 +filter {img-reorder}
8437 +filter {banners-by-size}
8439 +filter {jumping-windows}
8440 +filter {ie-exploits}
8447 -handle-as-empty-document
8449 -hide-accept-language
8450 -hide-content-disposition
8451 +hide-from-header {block}
8452 -hide-if-modified-since
8453 +hide-referrer {forge}
8456 -overwrite-last-modified
8457 -prevent-compression
8459 -server-header-filter{xml-to-html}
8460 -server-header-filter{html-to-xml}
8461 -session-cookies-only
8462 +set-image-blocker {pattern} </screen>
8466 Notice the only difference here to the previous listing, is to
8467 <quote>fast-redirects</quote> and <quote>session-cookies-only</quote>,
8468 which are activated specifically for this site in our configuration,
8469 and thus show in the <quote>Final Results</quote>.
8473 Now another example, <quote>ad.doubleclick.net</quote>:
8479 { +block{Domains starts with "ad"} }
8482 { +block{Domain contains "ad"} }
8485 { +block{Doubleclick banner server} +handle-as-image }
8486 .[a-vx-z]*.doubleclick.net
8491 We'll just show the interesting part here - the explicit matches. It is
8492 matched three different times. Two <quote>+block{}</quote> sections,
8493 and a <quote>+block{} +handle-as-image</quote>,
8494 which is the expanded form of one of our aliases that had been defined as:
8495 <quote>+block-as-image</quote>. (<link
8496 linkend="ALIASES"><quote>Aliases</quote></link> are defined in
8497 the first section of the actions file and typically used to combine more
8502 Any one of these would have done the trick and blocked this as an unwanted
8503 image. This is unnecessarily redundant since the last case effectively
8504 would also cover the first. No point in taking chances with these guys
8505 though ;-) Note that if you want an ad or obnoxious
8506 URL to be invisible, it should be defined as <quote>ad.doubleclick.net</quote>
8507 is done here -- as both a <link
8508 linkend="BLOCK"><quote>+block{}</quote></link>
8509 <emphasis>and</emphasis> an
8510 <link linkend="HANDLE-AS-IMAGE"><quote>+handle-as-image</quote></link>.
8511 The custom alias <quote><literal>+block-as-image</literal></quote> just
8512 simplifies the process and make it more readable.
8516 One last example. Let's try <quote>http://www.example.net/adsl/HOWTO/</quote>.
8517 This one is giving us problems. We are getting a blank page. Hmmm ...
8523 Matches for http://www.example.net/adsl/HOWTO/:
8525 In file: default.action <guibutton>[ View ]</guibutton> <guibutton>[ Edit ]</guibutton>
8529 +change-x-forwarded-for{block}
8530 -client-header-filter{hide-tor-exit-notation}
8531 -content-type-overwrite
8532 -crunch-client-header
8533 -crunch-if-none-match
8534 -crunch-incoming-cookies
8535 -crunch-outgoing-cookies
8536 -crunch-server-header
8538 -downgrade-http-version
8539 +fast-redirects {check-decoded-url}
8541 -filter {content-cookies}
8542 -filter {all-popups}
8543 -filter {banners-by-link}
8544 -filter {tiny-textforms}
8545 -filter {frameset-borders}
8546 -filter {demoronizer}
8547 -filter {shockwave-flash}
8548 -filter {quicktime-kioskmode}
8550 -filter {crude-parental}
8551 -filter {site-specifics}
8552 -filter {js-annoyances}
8553 -filter {html-annoyances}
8554 +filter {refresh-tags}
8555 -filter {unsolicited-popups}
8556 +filter {img-reorder}
8557 +filter {banners-by-size}
8559 +filter {jumping-windows}
8560 +filter {ie-exploits}
8567 -handle-as-empty-document
8569 -hide-accept-language
8570 -hide-content-disposition
8571 +hide-from-header{block}
8572 +hide-referer{forge}
8574 -overwrite-last-modified
8575 +prevent-compression
8577 -server-header-filter{xml-to-html}
8578 -server-header-filter{html-to-xml}
8579 +session-cookies-only
8580 +set-image-blocker{blank} }
8583 { +block{Path contains "ads".} +handle-as-image }
8589 Ooops, the <quote>/adsl/</quote> is matching <quote>/ads</quote> in our
8590 configuration! But we did not want this at all! Now we see why we get the
8591 blank page. It is actually triggering two different actions here, and
8592 the effects are aggregated so that the URL is blocked, and &my-app; is told
8593 to treat the block as if it were an image. But this is, of course, all wrong.
8594 We could now add a new action below this (or better in our own
8595 <filename>user.action</filename> file) that explicitly
8596 <emphasis>un</emphasis> blocks (
8597 <link linkend="BLOCK"><quote>{-block}</quote></link>) paths with
8598 <quote>adsl</quote> in them (remember, last match in the configuration
8599 wins). There are various ways to handle such exceptions. Example:
8611 Now the page displays ;-)
8612 Remember to flush your browser's caches when making these kinds of changes to
8613 your configuration to insure that you get a freshly delivered page! Or, try
8614 using <literal>Shift+Reload</literal>.
8618 But now what about a situation where we get no explicit matches like
8625 { +block{Path starts with "ads".} +handle-as-image }
8631 That actually was very helpful and pointed us quickly to where the problem
8632 was. If you don't get this kind of match, then it means one of the default
8633 rules in the first section of <filename>default.action</filename> is causing
8634 the problem. This would require some guesswork, and maybe a little trial and
8635 error to isolate the offending rule. One likely cause would be one of the
8636 <link linkend="FILTER"><quote>+filter</quote></link> actions.
8637 These tend to be harder to troubleshoot.
8638 Try adding the URL for the site to one of aliases that turn off
8639 <link linkend="FILTER"><quote>+filter</quote></link>:
8647 .worldpay.com # for quietpc.com
8655 <quote><literal>{ shop }</literal></quote> is an <quote>alias</quote> that expands to
8656 <quote><literal>{ -filter -session-cookies-only }</literal></quote>.
8657 Or you could do your own exception to negate filtering:
8665 # Disable ALL filter actions for sites in this section
8673 This would turn off all filtering for these sites. This is best
8674 put in <filename>user.action</filename>, for local site
8675 exceptions. Note that when a simple domain pattern is used by itself (without
8676 the subsequent path portion), all sub-pages within that domain are included
8677 automatically in the scope of the action.
8681 Images that are inexplicably being blocked, may well be hitting the
8682 <link linkend="FILTER-BANNERS-BY-SIZE"><quote>+filter{banners-by-size}</quote></link>
8684 that images of certain sizes are ad banners (works well
8685 <emphasis>most of the time</emphasis> since these tend to be standardized).
8689 <quote><literal>{ fragile }</literal></quote> is an alias that disables most
8690 actions that are the most likely to cause trouble. This can be used as a
8691 last resort for problem sites.
8697 # Handle with care: easy to break
8699 mybank.example.com</screen>
8704 <emphasis>Remember to flush caches!</emphasis> Note that the
8705 <literal>mail.google</literal> reference lacks the TLD portion (e.g.
8706 <quote>.com</quote>). This will effectively match any TLD with
8707 <literal>google</literal> in it, such as <literal>mail.google.de.</literal>,
8711 If this still does not work, you will have to go through the remaining
8712 actions one by one to find which one(s) is causing the problem.
8721 This program is free software; you can redistribute it
8722 and/or modify it under the terms of the GNU General
8723 Public License as published by the Free Software
8724 Foundation; either version 2 of the License, or (at
8725 your option) any later version.
8727 This program is distributed in the hope that it will
8728 be useful, but WITHOUT ANY WARRANTY; without even the
8729 implied warranty of MERCHANTABILITY or FITNESS FOR A
8730 PARTICULAR PURPOSE. See the GNU General Public
8731 License for more details.
8733 The GNU General Public License should be included with
8734 this file. If not, you can view it at
8735 http://www.gnu.org/copyleft/gpl.html
8736 or write to the Free Software Foundation, Inc.,
8737 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
projects / privoxy.git / blob