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">
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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 "3.0.25">
17 <!entity p-status "UNRELEASED">
18 <!entity % p-authors-formal "INCLUDE"> <!-- include additional text, etc -->
19 <!entity % p-not-stable "INCLUDE">
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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 -->
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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 $Id: user-manual.sgml,v 2.210 2016/05/03 13:20:20 fabiankeil Exp $
41 Copyright (C) 2001-2016 Privoxy Developers https://www.privoxy.org/
44 ========================================================================
45 NOTE: Please read developer-manual/documentation.html before touching
46 anything in this, or other Privoxy documentation.
47 ========================================================================
54 <title>Privoxy &p-version; User Manual</title>
58 <!-- Completely the wrong markup, but very little is allowed -->
59 <!-- in this part of an article. FIXME -->
60 <link linkend="copyright">Copyright</link> &my-copy; 2001-2016 by
61 <ulink url="https://www.privoxy.org/">Privoxy Developers</ulink>
65 <pubdate>$Id: user-manual.sgml,v 2.210 2016/05/03 13:20:20 fabiankeil Exp $</pubdate>
69 Note: the following should generate a separate page, and a live link to it,
70 all nicely done. But it doesn't for some mysterious reason. Please leave
71 commented unless it can be fixed proper. For the time being, the
72 copyright/license declarations will be in their own sgml.
85 This is here to keep vim syntax file from breaking :/
86 If I knew enough to fix it, I would.
87 PLEASE DO NOT REMOVE! HB: hal@foobox.net
93 The <citetitle>Privoxy User Manual</citetitle> gives users information on how to
94 install, configure and use <ulink
95 url="https://www.privoxy.org/">Privoxy</ulink>.
98 <!-- Include privoxy.sgml boilerplate: -->
100 <!-- end privoxy.sgml -->
103 You can find the latest version of the <citetitle>Privoxy User Manual</citetitle> at <ulink
104 url="https://www.privoxy.org/user-manual/">https://www.privoxy.org/user-manual/</ulink>.
105 Please see the <link linkend="contact">Contact section</link> on how to
106 contact the developers.
113 <!-- ~~~~~ New section ~~~~~ -->
114 <sect1 label="1" id="introduction"><title>Introduction</title>
116 This documentation is included with the current &p-status; version of
117 <application>Privoxy</application>, &p-version;<![%p-not-stable;[,
118 and is mostly complete at this point. The most up to date reference for the
119 time being is still the comments in the source files and in the individual
120 configuration files. Development of a new version is currently nearing
121 completion, and includes significant changes and enhancements over
125 <!-- include only in non-stable versions -->
128 Since this is a &p-status; version, not all new features are well tested. This
129 documentation may be slightly out of sync as a result (especially with
130 CVS sources). And there <emphasis>may be</emphasis> bugs, though hopefully
135 <!-- ~~~~~ New section ~~~~~ -->
136 <sect2 id="features"><title>Features</title>
138 In addition to the core
139 features of ad blocking and
140 <ulink url="http://en.wikipedia.org/wiki/Browser_cookie">cookie</ulink> management,
141 <application>Privoxy</application> provides many supplemental
142 features<![%p-not-stable;[, some of them currently under development]]>,
143 that give the end-user more control, more privacy and more freedom:
145 <!-- Include newfeatures.sgml boilerplate here: -->
147 <!-- end boilerplate -->
152 <!-- ~ End section ~ -->
155 <!-- ~~~~~ New section ~~~~~ -->
156 <sect1 id="installation"><title>Installation</title>
159 <application>Privoxy</application> is available both in convenient pre-compiled
160 packages for a wide range of operating systems, and as raw source code.
161 For most users, we recommend using the packages, which can be downloaded from our
162 <ulink url="https://sourceforge.net/projects/ijbswa/">Privoxy Project
168 On some platforms, the installer may remove previously installed versions, if
169 found. (See below for your platform). In any case <emphasis>be sure to backup
170 your old configuration if it is valuable to you.</emphasis> See the <link
171 linkend="upgradersnote">note to upgraders</link> section below.
174 <!-- ~~~~~ New section ~~~~~ -->
175 <sect2 id="installation-packages"><title>Binary Packages</title>
177 How to install the binary packages depends on your operating system:
180 <!-- XXX: The installation sections should be sorted -->
182 <!-- ~~~~~ New section ~~~~~ -->
183 <sect3 id="installation-deb"><title>Debian and Ubuntu</title>
185 DEBs can be installed with <literal>apt-get install privoxy</literal>,
186 and will use <filename>/etc/privoxy</filename> for the location of
191 <!-- ~~~~~ New section ~~~~~ -->
192 <sect3 id="installation-pack-win"><title>Windows</title>
195 Just double-click the installer, which will guide you through
196 the installation process. You will find the configuration files
197 in the same directory as you installed <application>Privoxy</application> in.
200 Version 3.0.5 beta introduced full <application>Windows</application> service
201 functionality. On Windows only, the <application>Privoxy</application>
202 program has two new command line arguments to install and uninstall
203 <application>Privoxy</application> as a <emphasis>service</emphasis>.
207 <term>Arguments:</term>
210 <replaceable class="parameter">--install</replaceable>[:<replaceable class="parameter">service_name</replaceable>]
213 <replaceable class="parameter">--uninstall</replaceable>[:<replaceable class="parameter">service_name</replaceable>]
219 After invoking <application>Privoxy</application> with
220 <command>--install</command>, you will need to bring up the
221 <application>Windows</application> service console to assign the user you
222 want <application>Privoxy</application> to run under, and whether or not you
223 want it to run whenever the system starts. You can start the
224 <application>Windows</application> services console with the following
225 command: <command>services.msc</command>. If you do not take the manual step
226 of modifying <application>Privoxy's</application> service settings, it will
227 not start. Note too that you will need to give Privoxy a user account that
228 actually exists, or it will not be permitted to
229 write to its log and configuration files.
234 <!-- ~~~~~ New section ~~~~~ -->
235 <sect3 id="installation-os2"><title>OS/2</title>
238 First, make sure that no previous installations of
239 <application>Junkbuster</application> and / or
240 <application>Privoxy</application> are left on your
241 system. Check that no <application>Junkbuster</application>
242 or <application>Privoxy</application> objects are in
248 Then, just double-click the WarpIN self-installing archive, which will
249 guide you through the installation process. A shadow of the
250 <application>Privoxy</application> executable will be placed in your
251 startup folder so it will start automatically whenever OS/2 starts.
255 The directory you choose to install <application>Privoxy</application>
256 into will contain all of the configuration files.
260 <!-- ~~~~~ New section ~~~~~ -->
261 <sect3 id="installation-mac"><title>Mac OS X</title>
263 Installation instructions for the OS X platform depend upon whether
264 you downloaded a ready-built installation package (.pkg or .mpkg) or have
265 downloaded the source code.
268 <sect3 renderas="sect4" id="OS-X-install-from-package">
269 <title>Installation from ready-built package</title>
271 The downloaded file will either be a .pkg (for OS X 10.5 upwards) or a bzipped
272 .mpkg file (for OS X 10.4). The former can be double-clicked as is and the
273 installation will start; double-clicking the latter will unzip the .mpkg file
274 which can then be double-clicked to commence the installation.
277 The privoxy service will automatically start after a successful installation
278 (and thereafter every time your computer starts up) however you will need to
279 configure your web browser(s) to use it. To do so, configure them to use a
280 proxy for HTTP and HTTPS at the address 127.0.0.1:8118.
283 To prevent the privoxy service from automatically starting when your computer
284 starts up, remove or rename the file <literal>/Library/LaunchDaemons/org.ijbswa.privoxy.plist</literal>
285 (on OS X 10.5 and higher) or the folder named
286 <literal>/Library/StartupItems/Privoxy</literal> (on OS X 10.4 'Tiger').
289 To manually start or stop the privoxy service, use the scripts startPrivoxy.sh
290 and stopPrivoxy.sh supplied in /Applications/Privoxy. They must be run from an
291 administrator account, using sudo.
294 To uninstall, run /Applications/Privoxy/uninstall.command as sudo from an
295 administrator account.
298 <sect3 renderas="sect4" id="OS-X-install-from-source">
299 <title>Installation from source</title>
301 To build and install the Privoxy source code on OS X you will need to obtain
302 the macsetup module from the Privoxy Sourceforge CVS repository (refer to
303 Sourceforge help for details of how to set up a CVS client to have read-only
304 access to the repository). This module contains scripts that leverage the usual
305 open-source tools (available as part of Apple's free of charge Xcode
306 distribution or via the usual open-source software package managers for OS X
307 (MacPorts, Homebrew, Fink etc.) to build and then install the privoxy binary
308 and associated files. The macsetup module's README file contains complete
309 instructions for its use.
312 The privoxy service will automatically start after a successful installation
313 (and thereafter every time your computer starts up) however you will need to
314 configure your web browser(s) to use it. To do so, configure them to use a
315 proxy for HTTP and HTTPS at the address 127.0.0.1:8118.
318 To prevent the privoxy service from automatically starting when your computer
319 starts up, remove or rename the file <literal>/Library/LaunchDaemons/org.ijbswa.privoxy.plist</literal>
320 (on OS X 10.5 and higher) or the folder named
321 <literal>/Library/StartupItems/Privoxy</literal> (on OS X 10.4 'Tiger').
324 To manually start or stop the privoxy service, use the Privoxy Utility
325 for Mac OS X (also part of the macsetup module). This application can start
326 and stop the privoxy service and display its log and configuration files.
329 To uninstall, run the macsetup module's uninstall.sh as sudo from an
330 administrator account.
334 <!-- ~~~~~ New section ~~~~~ -->
335 <sect3 id="installation-freebsd"><title>FreeBSD</title>
338 Privoxy is part of FreeBSD's Ports Collection, you can build and install
339 it with <literal>cd /usr/ports/www/privoxy; make install clean</literal>.
345 <!-- ~~~~~ New section ~~~~~ -->
346 <sect2 id="installation-source"><title>Building from Source</title>
349 The most convenient way to obtain the <application>Privoxy</application> sources
350 is to download the source tarball from our
351 <ulink url="https://sourceforge.net/projects/ijbswa/files/Sources/">project download
356 If you like to live on the bleeding edge and are not afraid of using
357 possibly unstable development versions, you can check out the up-to-the-minute
358 version directly from <ulink url="https://sourceforge.net/p/ijbswa/code/?source=navbar">the
359 CVS repository</ulink>.
361 deprecated...out of business.
362 or simply download <ulink
363 url="http://cvs.sourceforge.net/cvstarballs/ijbswa-cvsroot.tar.bz2">the nightly CVS
368 <!-- include buildsource.sgml boilerplate: -->
370 <!-- end boilerplate -->
373 <!-- ~~~~~ New section ~~~~~ -->
374 <sect2 id="installation-keepupdated"><title>Keeping your Installation Up-to-Date</title>
377 If you wish to receive an email notification whenever we release updates of
378 <application>Privoxy</application> or the actions file, <ulink
379 url="https://lists.privoxy.org/mailman/listinfo/privoxy-announce">subscribe
380 to our announce mailing list</ulink>, privoxy-announce@lists.privoxy.org.
384 In order not to lose your personal changes and adjustments when updating
385 to the latest <literal>default.action</literal> file we <emphasis>strongly
386 recommend</emphasis> that you use <literal>user.action</literal> and
387 <literal>user.filter</literal> for your local
388 customizations of <application>Privoxy</application>. See the <link
389 linkend="actions-file">Chapter on actions files</link> for details.
397 <!-- ~ End section ~ -->
399 <!-- ~~~~~ New section ~~~~~ -->
400 <sect1 id="whatsnew">
401 <title>What's New in this Release</title>
405 <!-- ~~~~~ New section ~~~~~ -->
407 <sect2 id="upgradersnote">
408 <title>Note to Upgraders</title>
411 A quick list of things to be aware of before upgrading from earlier
412 versions of <application>Privoxy</application>:
420 The recommended way to upgrade &my-app; is to backup your old
421 configuration files, install the new ones, verify that &my-app;
422 is working correctly and finally merge back your changes using
423 <application>diff</application> and maybe <application>patch</application>.
426 There are a number of new features in each &my-app; release and
427 most of them have to be explicitly enabled in the configuration
428 files. Old configuration files obviously don't do that and due
429 to syntax changes using old configuration files with a new
430 &my-app; isn't always possible anyway.
435 Note that some installers remove earlier versions completely,
436 including configuration files, therefore you should really save
437 any important configuration files!
442 On the other hand, other installers don't overwrite existing configuration
443 files, thinking you will want to do that yourself.
448 In the default configuration only fatal errors are logged now.
449 You can change that in the <link linkend="DEBUG">debug section</link>
450 of the configuration file. You may also want to enable more verbose
451 logging until you verified that the new &my-app; version is working
458 Three other config file settings are now off by default:
459 <link linkend="enable-remote-toggle">enable-remote-toggle</link>,
460 <link linkend="enable-remote-http-toggle">enable-remote-http-toggle</link>,
461 and <link linkend="enable-edit-actions">enable-edit-actions</link>.
462 If you use or want these, you will need to explicitly enable them, and
463 be aware of the security issues involved.
470 What constitutes a <quote>default</quote> configuration has changed,
471 and you may want to review which actions are <quote>on</quote> by
472 default. This is primarily a matter of emphasis, but some features
473 you may have been used to, may now be <quote>off</quote> by default.
474 There are also a number of new actions and filters you may want to
475 consider, most of which are not fully incorporated into the default
476 settings as yet (see above).
483 The default actions setting is now <literal>Cautious</literal>. Previous
484 releases had a default setting of <literal>Medium</literal>. Experienced
485 users may want to adjust this, as it is fairly conservative by &my-app;
486 standards and past practices. See <ulink
487 url="http://config.privoxy.org/edit-actions-list?f=default">
488 http://config.privoxy.org/edit-actions-list?f=default</ulink>. New users
489 should try the default settings for a while before turning up the volume.
495 The default setting has filtering turned <emphasis>off</emphasis>, which
496 subsequently means that compression is <emphasis>on</emphasis>. Remember
497 that filtering does not work on compressed pages, so if you use, or want to
498 use, filtering, you will need to force compression off. Example:
502 { +<link linkend="filter">filter</link>{google} +<link linkend="prevent-compression">prevent-compression</link> }
506 Or if you use a number of filters, or filter many sites, you may just want
507 to turn off compression for all sites in
508 <filename>default.action</filename> (or
509 <filename>user.action</filename>).
516 Also, <link linkend="SESSION-COOKIES-ONLY">session-cookies-only</link> is
517 off by default now. If you've liked this feature in the past, you may want
518 to turn it back on in <filename>user.action</filename> now.
525 Some installers may not automatically start
526 <application>Privoxy</application> after installation.
537 <!-- ~~~~~ New section ~~~~~ -->
538 <sect1 id="quickstart"><title>Quickstart to Using Privoxy</title>
544 Install <application>Privoxy</application>. See the <link
545 linkend="installation">Installation Section</link> below for platform specific
552 Advanced users and those who want to offer <application>Privoxy</application>
553 service to more than just their local machine should check the <link
554 linkend="config">main config file</link>, especially the <link
555 linkend="access-control">security-relevant</link> options. These are
562 Start <application>Privoxy</application>, if the installation program has
563 not done this already (may vary according to platform). See the section
564 <link linkend="startup">Starting <application>Privoxy</application></link>.
570 Set your browser to use <application>Privoxy</application> as HTTP and
571 HTTPS (SSL) <ulink url="http://en.wikipedia.org/wiki/Proxy_server">proxy</ulink>
572 by setting the proxy configuration for address of
573 <literal>127.0.0.1</literal> and port <literal>8118</literal>.
574 <emphasis>DO NOT</emphasis> activate proxying for <literal>FTP</literal> or
575 any protocols besides HTTP and HTTPS (SSL) unless you intend to prevent your
576 browser from using these protocols.
582 Flush your browser's disk and memory caches, to remove any cached ad images.
583 If using <application>Privoxy</application> to manage
584 <ulink url="http://en.wikipedia.org/wiki/Browser_cookie">cookies</ulink>,
585 you should remove any currently stored cookies too.
591 A default installation should provide a reasonable starting point for
592 most. There will undoubtedly be occasions where you will want to adjust the
593 configuration, but that can be dealt with as the need arises. Little
594 to no initial configuration is required in most cases, you may want
596 <ulink url="config.html#ENABLE-EDIT-ACTIONS">web-based action editor</ulink> though.
597 Be sure to read the warnings first.
600 See the <link linkend="configuration">Configuration section</link> for more
601 configuration options, and how to customize your installation.
602 You might also want to look at the <link
603 linkend="quickstart-ad-blocking">next section</link> for a quick
604 introduction to how <application>Privoxy</application> blocks ads and
611 If you experience ads that slip through, innocent images that are
612 blocked, or otherwise feel the need to fine-tune
613 <application>Privoxy's</application> behavior, take a look at the <link
614 linkend="actions-file">actions files</link>. As a quick start, you might
615 find the <link linkend="act-examples">richly commented examples</link>
616 helpful. You can also view and edit the actions files through the <ulink
617 url="http://config.privoxy.org">web-based user interface</ulink>. The
618 Appendix <quote><link linkend="actionsanat">Troubleshooting: Anatomy of an
619 Action</link></quote> has hints on how to understand and debug actions that
620 <quote>misbehave</quote>.
626 Please see the section <link linkend="contact">Contacting the
627 Developers</link> on how to report bugs, problems with websites or to get
634 Now enjoy surfing with enhanced control, comfort and privacy!
642 <!-- ~~~~~ New section ~~~~~ -->
644 <sect2 id="quickstart-ad-blocking">
645 <title>Quickstart to Ad Blocking</title>
647 NOTE: This section is deliberately redundant for those that don't
648 want to read the whole thing (which is getting lengthy).
651 Ad blocking is but one of <application>Privoxy's</application>
652 array of features. Many of these features are for the technically minded advanced
653 user. But, ad and banner blocking is surely common ground for everybody.
656 This section will provide a quick summary of ad blocking so
657 you can get up to speed quickly without having to read the more extensive
658 information provided below, though this is highly recommended.
661 First a bit of a warning ... blocking ads is much like blocking SPAM: the
662 more aggressive you are about it, the more likely you are to block
663 things that were not intended. And the more likely that some things
664 may not work as intended. So there is a trade off here. If you want
665 extreme ad free browsing, be prepared to deal with more
666 <quote>problem</quote> sites, and to spend more time adjusting the
667 configuration to solve these unintended consequences. In short, there is
668 not an easy way to eliminate <emphasis>all</emphasis> ads. Either take
669 the easy way and settle for <emphasis>most</emphasis> ads blocked with the
670 default configuration, or jump in and tweak it for your personal surfing
671 habits and preferences.
674 Secondly, a brief explanation of <application>Privoxy's </application>
675 <quote>actions</quote>. <quote>Actions</quote> in this context, are
676 the directives we use to tell <application>Privoxy</application> to perform
677 some task relating to HTTP transactions (i.e. web browsing). We tell
678 <application>Privoxy</application> to take some <quote>action</quote>. Each
679 action has a unique name and function. While there are many potential
680 <application>actions</application> in <application>Privoxy's</application>
681 arsenal, only a few are used for ad blocking. <link
682 linkend="actions">Actions</link>, and <link linkend="actions-file">action
683 configuration files</link>, are explained in depth below.
686 Actions are specified in <application>Privoxy's</application> configuration,
687 followed by one or more URLs to which the action should apply. URLs
688 can actually be URL type <link linkend="af-patterns">patterns</link> that use
689 wildcards so they can apply potentially to a range of similar URLs. The
690 actions, together with the URL patterns are called a section.
693 When you connect to a website, the full URL will either match one or more
694 of the sections as defined in <application>Privoxy's</application> configuration,
695 or not. If so, then <application>Privoxy</application> will perform the
696 respective actions. If not, then nothing special happens. Furthermore, web
697 pages may contain embedded, secondary URLs that your web browser will
698 use to load additional components of the page, as it parses the
699 original page's HTML content. An ad image for instance, is just an URL
700 embedded in the page somewhere. The image itself may be on the same server,
701 or a server somewhere else on the Internet. Complex web pages will have many
702 such embedded URLs. &my-app; can deal with each URL individually, so, for
703 instance, the main page text is not touched, but images from such-and-such
708 The most important actions for basic ad blocking are: <literal><link
709 linkend="block">block</link></literal>, <literal><link
710 linkend="handle-as-image">handle-as-image</link></literal>,
712 linkend="handle-as-empty-document">handle-as-empty-document</link></literal>,and
713 <literal><link linkend="set-image-blocker">set-image-blocker</link></literal>:
721 <literal><link linkend="block">block</link></literal> - this is perhaps
722 the single most used action, and is particularly important for ad blocking.
723 This action stops any contact between your browser and any URL patterns
724 that match this action's configuration. It can be used for blocking ads,
725 but also anything that is determined to be unwanted. By itself, it simply
726 stops any communication with the remote server and sends
727 <application>Privoxy</application>'s own built-in BLOCKED page instead to
728 let you now what has happened (with some exceptions, see below).
734 <literal><link linkend="handle-as-image">handle-as-image</link></literal> -
735 tells <application>Privoxy</application> to treat this URL as an image.
736 <application>Privoxy</application>'s default configuration already does this
737 for all common image types (e.g. GIF), but there are many situations where this
738 is not so easy to determine. So we'll force it in these cases. This is particularly
739 important for ad blocking, since only if we know that it's an image of
740 some kind, can we replace it with an image of our choosing, instead of the
741 <application>Privoxy</application> BLOCKED page (which would only result in
742 a <quote>broken image</quote> icon). There are some limitations to this
743 though. For instance, you can't just brute-force an image substitution for
744 an entire HTML page in most situations.
750 <literal><link linkend="handle-as-empty-document">handle-as-empty-document</link></literal> -
751 sends an empty document instead of <application>Privoxy's</application>
752 normal BLOCKED HTML page. This is useful for file types that are neither
753 HTML nor images, such as blocking JavaScript files.
760 linkend="set-image-blocker">set-image-blocker</link></literal> - tells
761 <application>Privoxy</application> what to display in place of an ad image that
762 has hit a block rule. For this to come into play, the URL must match a
763 <literal><link linkend="block">block</link></literal> action somewhere in the
764 configuration, <emphasis>and</emphasis>, it must also match an
765 <literal><link linkend="handle-as-image">handle-as-image</link></literal> action.
768 The configuration options on what to display instead of the ad are:
772 <emphasis>pattern</emphasis> - a checkerboard pattern, so that an ad
773 replacement is obvious. This is the default.
778 <emphasis>blank</emphasis> - A very small empty GIF image is displayed.
779 This is the so-called <quote>invisible</quote> configuration option.
784 <emphasis>http://<URL></emphasis> - A redirect to any image anywhere
785 of the user's choosing (advanced usage).
794 Advanced users will eventually want to explore &my-app;
795 <literal><link linkend="filter">filters</link></literal> as well. Filters
796 are very different from <literal><link
797 linkend="block">blocks</link></literal>.
798 A <quote>block</quote> blocks a site, page, or unwanted contented. Filters
799 are a way of filtering or modifying what is actually on the page. An example
800 filter usage: a text replacement of <quote>no-no</quote> for
801 <quote>nasty-word</quote>. That is a very simple example. This process can be
802 used for ad blocking, but it is more in the realm of advanced usage and has
803 some pitfalls to be wary off.
807 The quickest way to adjust any of these settings is with your browser through
808 the special <application>Privoxy</application> editor at <ulink
809 url="http://config.privoxy.org/show-status">http://config.privoxy.org/show-status</ulink>
810 (shortcut: <ulink url="http://p.p/">http://p.p/show-status</ulink>). This
811 is an internal page, and does not require Internet access.
815 Note that as of <application>Privoxy</application> 3.0.7 beta the
816 action editor is disabled by default. Check the
817 <ulink url="config.html#ENABLE-EDIT-ACTIONS">enable-edit-actions
818 section in the configuration file</ulink> to learn why and in which
819 cases it's safe to enable again.
823 If you decided to enable the action editor, select the appropriate
824 <quote>actions</quote> file, and click
825 <quote><guibutton>Edit</guibutton></quote>. It is best to put personal or
826 local preferences in <filename>user.action</filename> since this is not
827 meant to be overwritten during upgrades, and will over-ride the settings in
828 other files. Here you can insert new <quote>actions</quote>, and URLs for ad
829 blocking or other purposes, and make other adjustments to the configuration.
830 <application>Privoxy</application> will detect these changes automatically.
834 A quick and simple step by step example:
842 Right click on the ad image to be blocked, then select
843 <quote><guimenuitem>Copy Link Location</guimenuitem></quote> from the
851 url="http://config.privoxy.org/show-status">http://config.privoxy.org/show-status</ulink>
856 Find <filename>user.action</filename> in the top section, and click
857 on <quote><guibutton>Edit</guibutton></quote>:
860 <!-- image of editor and actions files selections -->
862 <figure pgwide="0" float="0"><title>Actions Files in Use</title>
865 <imagedata fileref="files-in-use.jpg" format="jpg">
868 <phrase>[ Screenshot of Actions Files in Use ]</phrase>
877 You should have a section with only
878 <literal><link linkend="block">block</link></literal> listed under
879 <quote>Actions:</quote>.
880 If not, click a <quote><guibutton>Insert new section below</guibutton></quote>
881 button, and in the new section that just appeared, click the
882 <guibutton>Edit</guibutton> button right under the word <quote>Actions:</quote>.
883 This will bring up a list of all actions. Find
884 <literal><link linkend="block">block</link></literal> near the top, and click
885 in the <quote>Enabled</quote> column, then <quote><guibutton>Submit</guibutton></quote>
891 Now, in the <literal><link linkend="block">block</link></literal> actions section,
892 click the <quote><guibutton>Add</guibutton></quote> button, and paste the URL the
893 browser got from <quote><guimenuitem>Copy Link Location</guimenuitem></quote>.
894 Remove the <literal>http://</literal> at the beginning of the URL. Then, click
895 <quote><guibutton>Submit</guibutton></quote> (or
896 <quote><guibutton>OK</guibutton></quote> if in a pop-up window).
901 Now go back to the original page, and press <keycap>SHIFT-Reload</keycap>
902 (or flush all browser caches). The image should be gone now.
910 This is a very crude and simple example. There might be good reasons to use a
911 wildcard pattern match to include potentially similar images from the same
912 site. For a more extensive explanation of <quote>patterns</quote>, and
913 the entire actions concept, see <link linkend="actions-file">the Actions
918 For advanced users who want to hand edit their config files, you might want
919 to now go to the <link linkend="act-examples">Actions Files Tutorial</link>.
920 The ideas explained therein also apply to the web-based editor.
923 There are also various
924 <link linkend="filter">filters</link> that can be used for ad blocking
925 (filters are a special subset of actions). These
926 fall into the <quote>advanced</quote> usage category, and are explained in
927 depth in later sections.
934 <!-- ~ End section ~ -->
937 <!-- ~~~~~ New section ~~~~~ -->
939 <title>Starting Privoxy</title>
941 Before launching <application>Privoxy</application> for the first time, you
942 will want to configure your browser(s) to use
943 <application>Privoxy</application> as a HTTP and HTTPS (SSL)
944 <ulink url="http://en.wikipedia.org/wiki/Proxy_server">proxy</ulink>. The default is
945 127.0.0.1 (or localhost) for the proxy address, and port 8118 (earlier versions
946 used port 8000). This is the one configuration step <emphasis>that must be done
950 Please note that <application>Privoxy</application> can only proxy HTTP and
951 HTTPS traffic. It will not work with FTP or other protocols.
954 <!-- image of Mozilla Proxy configuration -->
956 <figure pgwide="0" float="0"><title>Proxy Configuration Showing
957 Mozilla/Netscape HTTP and HTTPS (SSL) Settings</title>
960 <imagedata fileref="proxy_setup.jpg" format="jpg">
963 <phrase>[ Screenshot of Mozilla Proxy Configuration ]</phrase>
971 With <application>Firefox</application>, this is typically set under:
975 <guibutton>Tools</guibutton> -> <guibutton>Options</guibutton> -> <guibutton>Advanced</guibutton> -> <guibutton>Network</guibutton> -><guibutton>Connection</guibutton> -> <guibutton>Settings</guibutton>
980 Or optionally on some platforms:
984 <guibutton>Edit</guibutton> -> <guibutton>Preferences</guibutton> -> <guibutton>General</guibutton> -> <guibutton>Connection Settings</guibutton> -> <guibutton>Manual Proxy Configuration</guibutton>
990 With <application>Netscape</application> (and
991 <application>Mozilla</application>), this can be set under:
996 <!-- Mix ascii and gui art, something for everybody -->
997 <!-- spacing on this is tricky -->
998 <guibutton>Edit</guibutton> -> <guibutton>Preferences</guibutton> -> <guibutton>Advanced</guibutton> -> <guibutton>Proxies</guibutton> -> <guibutton>HTTP Proxy</guibutton>
1003 For <application>Internet Explorer v.5-7</application>:
1007 <guibutton>Tools</guibutton> -> <guibutton>Internet Options</guibutton> -> <guibutton>Connections</guibutton> -> <guibutton>LAN Settings</guibutton>
1011 Then, check <quote>Use Proxy</quote> and fill in the appropriate info
1012 (Address: 127.0.0.1, Port: 8118). Include HTTPS (SSL), if you want HTTPS
1013 proxy support too (sometimes labeled <quote>Secure</quote>). Make sure any
1014 checkboxes like <quote>Use the same proxy server for all protocols</quote> is
1015 <emphasis>UNCHECKED</emphasis>. You want only HTTP and HTTPS (SSL)!
1018 <!-- image of IE Proxy configuration -->
1020 <figure pgwide="0" float="0"><title>Proxy Configuration Showing
1021 Internet Explorer HTTP and HTTPS (Secure) Settings</title>
1024 <imagedata fileref="proxy2.jpg" format="jpg">
1027 <phrase>[ Screenshot of IE Proxy Configuration ]</phrase>
1035 After doing this, flush your browser's disk and memory caches to force a
1036 re-reading of all pages and to get rid of any ads that may be cached. Remove
1037 any <ulink url="http://en.wikipedia.org/wiki/Browser_cookie">cookies</ulink>,
1038 if you want <application>Privoxy</application> to manage that. You are now
1039 ready to start enjoying the benefits of using
1040 <application>Privoxy</application>!
1044 <application>Privoxy</application> itself is typically started by specifying the
1045 main configuration file to be used on the command line. If no configuration
1046 file is specified on the command line, <application>Privoxy</application>
1047 will look for a file named <filename>config</filename> in the current
1048 directory. Except on Win32 where it will try <filename>config.txt</filename>.
1051 <sect2 id="start-debian">
1052 <title>Debian</title>
1054 We use a script. Note that Debian typically starts &my-app; upon booting per
1055 default. It will use the file
1056 <filename>/etc/privoxy/config</filename> as its main configuration
1061 # /etc/init.d/privoxy start
1066 <sect2 id="start-freebsd">
1067 <title>FreeBSD and ElectroBSD</title>
1069 To start <application>Privoxy</application> upon booting, add
1070 "privoxy_enable='YES'" to <filename>/etc/rc.conf</filename>.
1071 <application>Privoxy</application> will use
1072 <filename>/usr/local/etc/privoxy/config</filename> as its main
1076 If you installed <application>Privoxy</application> into a jail, the
1077 paths above are relative to the jail root.
1080 To start <application>Privoxy</application> manually, run:
1084 # service privoxy onestart
1089 <sect2 id="start-windows">
1090 <title>Windows</title>
1092 Click on the &my-app; Icon to start <application>Privoxy</application>. If no configuration file is
1093 specified on the command line, <application>Privoxy</application> will look
1094 for a file named <filename>config.txt</filename>. Note that Windows will
1095 automatically start &my-app; when the system starts if you chose that option
1099 <application>Privoxy</application> can run with full Windows service functionality.
1100 On Windows only, the &my-app; program has two new command line arguments
1101 to install and uninstall &my-app; as a service. See the
1102 <link linkend="installation-pack-win">Windows Installation
1103 instructions</link> for details.
1107 <sect2 id="start-unices">
1108 <title>Generic instructions for Unix derivates (Solaris, NetBSD, HP-UX etc.)</title>
1110 Example Unix startup command:
1114 # /usr/sbin/privoxy --user privoxy /etc/privoxy/config
1118 Note that if you installed <application>Privoxy</application> through
1119 a package manager, the package will probably contain a platform-specific
1120 script or configuration file to start <application>Privoxy</application>
1125 <sect2 id="start-os2">
1128 During installation, <application>Privoxy</application> is configured to
1129 start automatically when the system restarts. You can start it manually by
1130 double-clicking on the <application>Privoxy</application> icon in the
1131 <application>Privoxy</application> folder.
1135 <sect2 id="start-macosx">
1136 <title>Mac OS X</title>
1138 The privoxy service will automatically start after a successful installation
1139 (and thereafter every time your computer starts up) however you will need to
1140 configure your web browser(s) to use it. To do so, configure them to use a
1141 proxy for HTTP and HTTPS at the address 127.0.0.1:8118.
1144 To prevent the privoxy service from automatically starting when your computer
1145 starts up, remove or rename the file <literal>/Library/LaunchDaemons/org.ijbswa.privoxy.plist</literal>
1146 (on OS X 10.5 and higher) or the folder named
1147 <literal>/Library/StartupItems/Privoxy</literal> (on OS X 10.4 'Tiger').
1150 To manually start or stop the privoxy service, use the scripts startPrivoxy.sh
1151 and stopPrivoxy.sh supplied in /Applications/Privoxy. They must be run from an
1152 administrator account, using sudo.
1160 See the section <link linkend="cmdoptions">Command line options</link> for
1164 must find a better place for this paragraph
1167 The included default configuration files should give a reasonable starting
1168 point. Most of the per site configuration is done in the
1169 <ulink url="actions-file.html"><quote>actions</quote></ulink> files. These are
1170 where various cookie actions are defined, ad and banner blocking, and other
1171 aspects of <application>Privoxy</application> configuration. There are several
1172 such files included, with varying levels of aggressiveness.
1176 You will probably want to keep an eye out for sites for which you may prefer
1177 persistent cookies, and add these to your actions configuration as needed. By
1178 default, most of these will be accepted only during the current browser
1179 session (aka <quote>session cookies</quote>), unless you add them to the
1180 configuration. If you want the browser to handle this instead, you will need
1181 to edit <filename>user.action</filename> (or through the web based interface)
1182 and disable this feature. If you use more than one browser, it would make
1183 more sense to let <application>Privoxy</application> handle this. In which
1184 case, the browser(s) should be set to accept all cookies.
1188 Another feature where you will probably want to define exceptions for trusted
1189 sites is the popup-killing (through <ulink
1190 url="actions-file.html#FILTER-POPUPS"><quote>+filter{popups}</quote></ulink>),
1191 because your favorite shopping, banking, or leisure site may need
1192 popups (explained below).
1196 <application>Privoxy</application> does not support all of the optional HTTP/1.1
1197 features yet. In the unlikely event that you experience inexplicable problems
1198 with browsers that use HTTP/1.1 per default
1199 (like <application>Mozilla</application> or recent versions of I.E.), you might
1200 try to force HTTP/1.0 compatibility. For Mozilla, look under <literal>Edit ->
1201 Preferences -> Debug -> Networking</literal>.
1202 Alternatively, set the <quote>+downgrade-http-version</quote> config option in
1203 <filename>default.action</filename> which will downgrade your browser's HTTP
1204 requests from HTTP/1.1 to HTTP/1.0 before processing them.
1208 After running <application>Privoxy</application> for a while, you can
1209 start to fine tune the configuration to suit your personal, or site,
1210 preferences and requirements. There are many, many aspects that can
1211 be customized. <quote>Actions</quote>
1212 can be adjusted by pointing your browser to
1213 <ulink url="http://config.privoxy.org/">http://config.privoxy.org/</ulink>
1214 (shortcut: <ulink url="http://p.p/">http://p.p/</ulink>),
1215 and then follow the link to <quote>View & Change the Current Configuration</quote>.
1216 (This is an internal page and does not require Internet access.)
1220 In fact, various aspects of <application>Privoxy</application>
1221 configuration can be viewed from this page, including
1222 current configuration parameters, source code version numbers,
1223 the browser's request headers, and <quote>actions</quote> that apply
1224 to a given URL. In addition to the actions file
1225 editor mentioned above, <application>Privoxy</application> can also
1226 be turned <quote>on</quote> and <quote>off</quote> (toggled) from this page.
1230 If you encounter problems, try loading the page without
1231 <application>Privoxy</application>. If that helps, enter the URL where
1232 you have the problems into <ulink url="http://p.p/show-url-info">the browser
1233 based rule tracing utility</ulink>. See which rules apply and why, and
1234 then try turning them off for that site one after the other, until the problem
1235 is gone. When you have found the culprit, you might want to turn the rest on
1240 If the above paragraph sounds gibberish to you, you might want to <link
1241 linkend="actions-file">read more about the actions concept</link>
1242 or even dive deep into the <link linkend="actionsanat">Appendix
1247 If you can't get rid of the problem at all, think you've found a bug in
1248 Privoxy, want to propose a new feature or smarter rules, please see the
1249 section <link linkend="contact"><quote>Contacting the
1250 Developers</quote></link> below.
1255 <!-- ~~~~~ New section ~~~~~ -->
1256 <sect2 id="cmdoptions">
1257 <title>Command Line Options</title>
1259 <application>Privoxy</application> may be invoked with the following
1260 command-line options:
1268 <emphasis>--config-test</emphasis>
1271 Exit after loading the configuration files before binding to
1272 the listen address. The exit code signals whether or not the
1273 configuration files have been successfully loaded.
1276 If the exit code is 1, at least one of the configuration files
1277 is invalid, if it is 0, all the configuration files have been
1278 successfully loaded (but may still contain errors that can
1279 currently only be detected at run time).
1282 This option doesn't affect the log setting, combination with
1283 <emphasis>--no-daemon</emphasis> is recommended if a configured
1284 log file shouldn't be used.
1289 <emphasis>--version</emphasis>
1292 Print version info and exit. Unix only.
1297 <emphasis>--help</emphasis>
1300 Print short usage info and exit. Unix only.
1305 <emphasis>--no-daemon</emphasis>
1308 Don't become a daemon, i.e. don't fork and become process group
1309 leader, and don't detach from controlling tty. Unix only.
1314 <emphasis>--pidfile FILE</emphasis>
1317 On startup, write the process ID to <emphasis>FILE</emphasis>. Delete the
1318 <emphasis>FILE</emphasis> on exit. Failure to create or delete the
1319 <emphasis>FILE</emphasis> is non-fatal. If no <emphasis>FILE</emphasis>
1320 option is given, no PID file will be used. Unix only.
1325 <emphasis>--user USER[.GROUP]</emphasis>
1328 After (optionally) writing the PID file, assume the user ID of
1329 <emphasis>USER</emphasis>, and if included the GID of GROUP. Exit if the
1330 privileges are not sufficient to do so. Unix only.
1335 <emphasis>--chroot</emphasis>
1338 Before changing to the user ID given in the <emphasis>--user</emphasis> option,
1339 chroot to that user's home directory, i.e. make the kernel pretend to the &my-app;
1340 process that the directory tree starts there. If set up carefully, this can limit
1341 the impact of possible vulnerabilities in &my-app; to the files contained in that hierarchy.
1347 <emphasis>--pre-chroot-nslookup hostname</emphasis>
1350 Specifies a hostname (for example www.privoxy.org) to look up before doing a chroot.
1351 On some systems, initializing the resolver library involves reading config files from
1352 /etc and/or loading additional shared libraries from /lib.
1353 On these systems, doing a hostname lookup before the chroot reduces
1354 the number of files that must be copied into the chroot tree.
1357 For fastest startup speed, a good value is a hostname that is not in /etc/hosts but that
1358 your local name server (listed in /etc/resolv.conf) can resolve without recursion
1359 (that is, without having to ask any other name servers). The hostname need not exist,
1360 but if it doesn't, an error message (which can be ignored) will be output.
1366 <emphasis>configfile</emphasis>
1369 If no <emphasis>configfile</emphasis> is included on the command line,
1370 <application>Privoxy</application> will look for a file named
1371 <quote>config</quote> in the current directory (except on Win32
1372 where it will look for <quote>config.txt</quote> instead). Specify
1373 full path to avoid confusion. If no config file is found,
1374 <application>Privoxy</application> will fail to start.
1382 On <application>MS Windows</application> only there are two additional
1383 command-line options to allow <application>Privoxy</application> to install and
1384 run as a <emphasis>service</emphasis>. See the
1385 <link linkend="installation-pack-win">Window Installation section</link>
1393 <!-- ~ End section ~ -->
1396 <!-- ~~~~~ New section ~~~~~ -->
1397 <sect1 id="configuration"><title>Privoxy Configuration</title>
1399 All <application>Privoxy</application> configuration is stored
1400 in text files. These files can be edited with a text editor.
1401 Many important aspects of <application>Privoxy</application> can
1402 also be controlled easily with a web browser.
1406 <!-- ~~~~~ New section ~~~~~ -->
1408 <sect2 id="control-with-webbrowser">
1409 <title>Controlling Privoxy with Your Web Browser</title>
1411 <application>Privoxy</application>'s user interface can be reached through the special
1412 URL <ulink url="http://config.privoxy.org/">http://config.privoxy.org/</ulink>
1413 (shortcut: <ulink url="http://p.p/">http://p.p/</ulink>),
1414 which is a built-in page and works without Internet access.
1415 You will see the following section:
1419 <!-- Needs to be put in a table and colorized -->
1422 <bridgehead renderas="sect2"> Privoxy Menu</bridgehead>
1426 ▪ <ulink url="http://config.privoxy.org/show-status">View & change the current configuration</ulink>
1429 ▪ <ulink url="http://config.privoxy.org/show-version">View the source code version numbers</ulink>
1432 ▪ <ulink url="http://config.privoxy.org/show-request">View the request headers.</ulink>
1435 ▪ <ulink url="http://config.privoxy.org/show-url-info">Look up which actions apply to a URL and why</ulink>
1438 ▪ <ulink url="http://config.privoxy.org/toggle">Toggle Privoxy on or off</ulink>
1441 ▪ <ulink
1442 url="https://www.privoxy.org/&p-version;/user-manual/">Documentation</ulink>
1450 This should be self-explanatory. Note the first item leads to an editor for the
1451 <link linkend="actions-file">actions files</link>, which is where the ad, banner,
1452 cookie, and URL blocking magic is configured as well as other advanced features of
1453 <application>Privoxy</application>. This is an easy way to adjust various
1454 aspects of <application>Privoxy</application> configuration. The actions
1455 file, and other configuration files, are explained in detail below.
1459 <quote>Toggle Privoxy On or Off</quote> is handy for sites that might
1460 have problems with your current actions and filters. You can in fact use
1461 it as a test to see whether it is <application>Privoxy</application>
1462 causing the problem or not. <application>Privoxy</application> continues
1463 to run as a proxy in this case, but all manipulation is disabled, i.e.
1464 <application>Privoxy</application> acts like a normal forwarding proxy.
1468 Note that several of the features described above are disabled by default
1469 in <application>Privoxy</application> 3.0.7 beta and later.
1471 <ulink url="config.html">configuration file</ulink> to learn why
1472 and in which cases it's safe to enable them again.
1477 <!-- ~ End section ~ -->
1482 <!-- ~~~~~ New section ~~~~~ -->
1484 <sect2 id="confoverview">
1485 <title>Configuration Files Overview</title>
1487 For Unix, *BSD and Linux, all configuration files are located in
1488 <filename>/etc/privoxy/</filename> by default. For MS Windows, OS/2, and
1489 AmigaOS these are all in the same directory as the
1490 <application>Privoxy</application> executable. <![%p-not-stable;[ The name
1491 and number of configuration files has changed from previous versions, and is
1492 subject to change as development progresses.]]>
1496 The installed defaults provide a reasonable starting point, though
1497 some settings may be aggressive by some standards. For the time being, the
1498 principle configuration files are:
1506 The <link linkend="config">main configuration file</link> is named <filename>config</filename>
1507 on Linux, Unix, BSD, OS/2, and AmigaOS and <filename>config.txt</filename>
1508 on Windows. This is a required file.
1514 <filename>match-all.action</filename> is used to define which <quote>actions</quote>
1515 relating to banner-blocking, images, pop-ups, content modification, cookie handling
1516 etc should be applied by default. It should be the first actions file loaded.
1519 <filename>default.action</filename> defines many exceptions (both positive and negative)
1520 from the default set of actions that's configured in <filename>match-all.action</filename>.
1521 It should be the second actions file loaded and shouldn't be edited by the user.
1524 Multiple actions files may be defined in <filename>config</filename>. These
1525 are processed in the order they are defined. Local customizations and locally
1526 preferred exceptions to the default policies as defined in
1527 <filename>match-all.action</filename> (which you will most probably want
1528 to define sooner or later) are best applied in <filename>user.action</filename>,
1529 where you can preserve them across upgrades. The file isn't installed by all
1530 installers, but you can easily create it yourself with a text editor.
1533 There is also a web based editor that can be accessed from
1535 url="http://config.privoxy.org/show-status">http://config.privoxy.org/show-status</ulink>
1537 url="http://p.p/show-status">http://p.p/show-status</ulink>) for the
1538 various actions files.
1544 <quote>Filter files</quote> (the <link linkend="filter-file">filter
1545 file</link>) can be used to re-write the raw page content, including
1546 viewable text as well as embedded HTML and JavaScript, and whatever else
1547 lurks on any given web page. The filtering jobs are only pre-defined here;
1548 whether to apply them or not is up to the actions files.
1549 <filename>default.filter</filename> includes various filters made
1550 available for use by the developers. Some are much more intrusive than
1551 others, and all should be used with caution. You may define additional
1552 filter files in <filename>config</filename> as you can with
1553 actions files. We suggest <filename>user.filter</filename> for any
1554 locally defined filters or customizations.
1562 The syntax of the configuration and filter files may change between different
1563 Privoxy versions, unfortunately some enhancements cost backwards compatibility.
1564 <!-- Add link to documentation-->
1568 All files use the <quote><literal>#</literal></quote> character to denote a
1569 comment (the rest of the line will be ignored) and understand line continuation
1570 through placing a backslash ("<literal>\</literal>") as the very last character
1571 in a line. If the <literal>#</literal> is preceded by a backslash, it looses
1572 its special function. Placing a <literal>#</literal> in front of an otherwise
1573 valid configuration line to prevent it from being interpreted is called "commenting
1574 out" that line. Blank lines are ignored.
1578 The actions files and filter files
1579 can use Perl style <link linkend="regex">regular expressions</link> for
1580 maximum flexibility.
1584 After making any changes, there is no need to restart
1585 <application>Privoxy</application> in order for the changes to take
1586 effect. <application>Privoxy</application> detects such changes
1587 automatically. Note, however, that it may take one or two additional
1588 requests for the change to take effect. When changing the listening address
1589 of <application>Privoxy</application>, these <quote>wake up</quote> requests
1590 must obviously be sent to the <emphasis>old</emphasis> listening address.
1595 While under development, the configuration content is subject to change.
1596 The below documentation may not be accurate by the time you read this.
1597 Also, what constitutes a <quote>default</quote> setting, may change, so
1598 please check all your configuration files on important issues.
1604 <!-- ~ End section ~ -->
1607 <!-- ~~~~~~~~ New section Header ~~~~~~~~~ -->
1609 <!-- **************************************************** -->
1610 <!-- Include config.sgml here -->
1611 <!-- This is where the entire config file is detailed. -->
1613 <!-- end include -->
1616 <!-- ~ End section ~ -->
1620 <!-- ~~~~~~~~ New section Header ~~~~~~~~~ -->
1622 <sect1 id="actions-file"><title>Actions Files</title>
1626 XXX: similar descriptions are in the Configuration Files sections.
1627 We should only describe them at one place.
1630 The actions files are used to define what <emphasis>actions</emphasis>
1631 <application>Privoxy</application> takes for which URLs, and thus determines
1632 how ad images, cookies and various other aspects of HTTP content and
1633 transactions are handled, and on which sites (or even parts thereof).
1634 There are a number of such actions, with a wide range of functionality.
1635 Each action does something a little different.
1636 These actions give us a veritable arsenal of tools with which to exert
1637 our control, preferences and independence. Actions can be combined so that
1638 their effects are aggregated when applied against a given set of URLs.
1642 are three action files included with <application>Privoxy</application> with
1649 <filename>match-all.action</filename> - is used to define which
1650 <quote>actions</quote> relating to banner-blocking, images, pop-ups,
1651 content modification, cookie handling etc should be applied by default.
1652 It should be the first actions file loaded
1657 <filename>default.action</filename> - defines many exceptions (both
1658 positive and negative) from the default set of actions that's configured
1659 in <filename>match-all.action</filename>. It is a set of rules that should
1660 work reasonably well as-is for most users. This file is only supposed to
1661 be edited by the developers. It should be the second actions file loaded.
1666 <filename>user.action</filename> - is intended to be for local site
1667 preferences and exceptions. As an example, if your ISP or your bank
1668 has specific requirements, and need special handling, this kind of
1669 thing should go here. This file will not be upgraded.
1674 <guibutton>Edit</guibutton> <guibutton>Set to Cautious</guibutton> <guibutton>Set to Medium</guibutton> <guibutton>Set to Advanced</guibutton>
1677 These have increasing levels of aggressiveness <emphasis>and have no
1678 influence on your browsing unless you select them explicitly in the
1679 editor</emphasis>. A default installation should be pre-set to
1680 <literal>Cautious</literal>. New users should try this for a while before
1681 adjusting the settings to more aggressive levels. The more aggressive
1682 the settings, then the more likelihood there is of problems such as sites
1683 not working as they should.
1686 The <guibutton>Edit</guibutton> button allows you to turn each
1687 action on/off individually for fine-tuning. The <guibutton>Cautious</guibutton>
1688 button changes the actions list to low/safe settings which will activate
1689 ad blocking and a minimal set of &my-app;'s features, and subsequently
1690 there will be less of a chance for accidental problems. The
1691 <guibutton>Medium</guibutton> button sets the list to a medium level of
1692 other features and a low level set of privacy features. The
1693 <guibutton>Advanced</guibutton> button sets the list to a high level of
1694 ad blocking and medium level of privacy. See the chart below. The latter
1695 three buttons over-ride any changes via with the
1696 <guibutton>Edit</guibutton> button. More fine-tuning can be done in the
1697 lower sections of this internal page.
1700 While the actions file editor allows to enable these settings in all
1701 actions files, they are only supposed to be enabled in the first one
1702 to make sure you don't unintentionally overrule earlier rules.
1705 The default profiles, and their associated actions, as pre-defined in
1706 <filename>default.action</filename> are:
1709 <table frame=all><title>Default Configurations</title>
1710 <tgroup cols=4 align=left colsep=1 rowsep=1>
1711 <colspec colname=c1>
1712 <colspec colname=c2>
1713 <colspec colname=c3>
1714 <colspec colname=c4>
1717 <entry>Feature</entry>
1718 <entry>Cautious</entry>
1719 <entry>Medium</entry>
1720 <entry>Advanced</entry>
1725 <!-- <entry>f1</entry> -->
1726 <!-- <entry>f2</entry> -->
1727 <!-- <entry>f3</entry> -->
1728 <!-- <entry>f4</entry> -->
1734 <entry>Ad-blocking Aggressiveness</entry>
1735 <entry>medium</entry>
1741 <entry>Ad-filtering by size</entry>
1748 <entry>Ad-filtering by link</entry>
1754 <entry>Pop-up killing</entry>
1755 <entry>blocks only</entry>
1756 <entry>blocks only</entry>
1757 <entry>blocks only</entry>
1761 <entry>Privacy Features</entry>
1763 <entry>medium</entry>
1764 <entry>medium/high</entry>
1768 <entry>Cookie handling</entry>
1770 <entry>session-only</entry>
1775 <entry>Referer forging</entry>
1782 <entry>GIF de-animation</entry>
1789 <entry>Fast redirects</entry>
1796 <entry>HTML taming</entry>
1803 <entry>JavaScript taming</entry>
1810 <entry>Web-bug killing</entry>
1817 <entry>Image tag reordering</entry>
1833 The list of actions files to be used are defined in the main configuration
1834 file, and are processed in the order they are defined (e.g.
1835 <filename>default.action</filename> is typically processed before
1836 <filename>user.action</filename>). The content of these can all be viewed and
1838 url="http://config.privoxy.org/show-status">http://config.privoxy.org/show-status</ulink>.
1839 The over-riding principle when applying actions, is that the last action that
1840 matches a given URL wins. The broadest, most general rules go first
1841 (defined in <filename>default.action</filename>),
1842 followed by any exceptions (typically also in
1843 <filename>default.action</filename>), which are then followed lastly by any
1844 local preferences (typically in <emphasis>user</emphasis><filename>.action</filename>).
1845 Generally, <filename>user.action</filename> has the last word.
1849 An actions file typically has multiple sections. If you want to use
1850 <quote>aliases</quote> in an actions file, you have to place the (optional)
1851 <link linkend="aliases">alias section</link> at the top of that file.
1852 Then comes the default set of rules which will apply universally to all
1853 sites and pages (be <emphasis>very careful</emphasis> with using such a
1854 universal set in <filename>user.action</filename> or any other actions file after
1855 <filename>default.action</filename>, because it will override the result
1856 from consulting any previous file). And then below that,
1857 exceptions to the defined universal policies. You can regard
1858 <filename>user.action</filename> as an appendix to <filename>default.action</filename>,
1859 with the advantage that it is a separate file, which makes preserving your
1860 personal settings across <application>Privoxy</application> upgrades easier.
1864 Actions can be used to block anything you want, including ads, banners, or
1865 just some obnoxious URL whose content you would rather not see. Cookies can be accepted
1866 or rejected, or accepted only during the current browser session (i.e. not
1867 written to disk), content can be modified, some JavaScripts tamed, user-tracking
1868 fooled, and much more. See below for a <link linkend="actions">complete list
1872 <!-- ~~~~~ New section ~~~~~ -->
1873 <sect2 id="right-mix">
1874 <title>Finding the Right Mix</title>
1876 Note that some <link linkend="actions">actions</link>, like cookie suppression
1877 or script disabling, may render some sites unusable that rely on these
1878 techniques to work properly. Finding the right mix of actions is not always easy and
1879 certainly a matter of personal taste. And, things can always change, requiring
1880 refinements in the configuration. In general, it can be said that the more
1881 <quote>aggressive</quote> your default settings (in the top section of the
1882 actions file) are, the more exceptions for <quote>trusted</quote> sites you
1883 will have to make later. If, for example, you want to crunch all cookies per
1884 default, you'll have to make exceptions from that rule for sites that you
1885 regularly use and that require cookies for actually useful purposes, like maybe
1886 your bank, favorite shop, or newspaper.
1890 We have tried to provide you with reasonable rules to start from in the
1891 distribution actions files. But there is no general rule of thumb on these
1892 things. There just are too many variables, and sites are constantly changing.
1893 Sooner or later you will want to change the rules (and read this chapter again :).
1897 <!-- ~~~~~ New section ~~~~~ -->
1898 <sect2 id="how-to-edit">
1899 <title>How to Edit</title>
1901 The easiest way to edit the actions files is with a browser by
1902 using our browser-based editor, which can be reached from <ulink
1903 url="http://config.privoxy.org/show-status">http://config.privoxy.org/show-status</ulink>.
1904 Note: the config file option <link
1905 linkend="enable-edit-actions">enable-edit-actions</link> must be enabled for
1906 this to work. The editor allows both fine-grained control over every single
1907 feature on a per-URL basis, and easy choosing from wholesale sets of defaults
1908 like <quote>Cautious</quote>, <quote>Medium</quote> or
1909 <quote>Advanced</quote>. Warning: the <quote>Advanced</quote> setting is more
1910 aggressive, and will be more likely to cause problems for some sites.
1911 Experienced users only!
1915 If you prefer plain text editing to GUIs, you can of course also directly edit the
1916 the actions files with your favorite text editor. Look at
1917 <filename>default.action</filename> which is richly commented with many
1923 <sect2 id="actions-apply">
1924 <title>How Actions are Applied to Requests</title>
1926 Actions files are divided into sections. There are special sections,
1927 like the <quote><link linkend="aliases">alias</link></quote> sections which will
1928 be discussed later. For now let's concentrate on regular sections: They have a
1929 heading line (often split up to multiple lines for readability) which consist
1930 of a list of actions, separated by whitespace and enclosed in curly braces.
1931 Below that, there is a list of URL and tag patterns, each on a separate line.
1935 To determine which actions apply to a request, the URL of the request is
1936 compared to all URL patterns in each <quote>action file</quote>.
1937 Every time it matches, the list of applicable actions for the request is
1938 incrementally updated, using the heading of the section in which the
1939 pattern is located. The same is done again for tags and tag patterns later on.
1943 If multiple applying sections set the same action differently,
1944 the last match wins. If not, the effects are aggregated.
1945 E.g. a URL might match a regular section with a heading line of <literal>{
1946 +<link linkend="handle-as-image">handle-as-image</link> }</literal>,
1947 then later another one with just <literal>{
1948 +<link linkend="block">block</link> }</literal>, resulting
1949 in <emphasis>both</emphasis> actions to apply. And there may well be
1950 cases where you will want to combine actions together. Such a section then
1956 { +<literal>handle-as-image</literal> +<literal>block{Banner ads.}</literal> }
1957 # Block these as if they were images. Send no block page.
1959 media.example.com/.*banners
1960 .example.com/images/ads/</screen>
1964 You can trace this process for URL patterns and any given URL by visiting <ulink
1965 url="http://config.privoxy.org/show-url-info">http://config.privoxy.org/show-url-info</ulink>.
1969 Examples and more detail on this is provided in the Appendix, <link linkend="ACTIONSANAT">
1970 Troubleshooting: Anatomy of an Action</link> section.
1974 <!-- ~~~~~ New section ~~~~~ -->
1975 <sect2 id="af-patterns">
1976 <title>Patterns</title>
1978 As mentioned, <application>Privoxy</application> uses <quote>patterns</quote>
1979 to determine what <emphasis>actions</emphasis> might apply to which sites and
1980 pages your browser attempts to access. These <quote>patterns</quote> use wild
1981 card type <emphasis>pattern</emphasis> matching to achieve a high degree of
1982 flexibility. This allows one expression to be expanded and potentially match
1983 against many similar patterns.
1987 Generally, an URL pattern has the form
1988 <literal><host><port>/<path></literal>, where the
1989 <literal><host></literal>, the <literal><port></literal>
1990 and the <literal><path></literal> are optional. (This is why the special
1991 <literal>/</literal> pattern matches all URLs). Note that the protocol
1992 portion of the URL pattern (e.g. <literal>http://</literal>) should
1993 <emphasis>not</emphasis> be included in the pattern. This is assumed already!
1996 The pattern matching syntax is different for the host and path parts of
1997 the URL. The host part uses a simple globbing type matching technique,
1998 while the path part uses more flexible
1999 <ulink url="http://en.wikipedia.org/wiki/Regular_expressions"><quote>Regular
2000 Expressions</quote></ulink> (POSIX 1003.2).
2003 The port part of a pattern is a decimal port number preceded by a colon
2004 (<literal>:</literal>). If the host part contains a numerical IPv6 address,
2005 it has to be put into angle brackets
2006 (<literal><</literal>, <literal>></literal>).
2011 <term><literal>www.example.com/</literal></term>
2014 is a host-only pattern and will match any request to <literal>www.example.com</literal>,
2015 regardless of which document on that server is requested. So ALL pages in
2016 this domain would be covered by the scope of this action. Note that a
2017 simple <literal>example.com</literal> is different and would NOT match.
2022 <term><literal>www.example.com</literal></term>
2025 means exactly the same. For host-only patterns, the trailing <literal>/</literal> may
2031 <term><literal>www.example.com/index.html</literal></term>
2034 matches all the documents on <literal>www.example.com</literal>
2035 whose name starts with <literal>/index.html</literal>.
2040 <term><literal>www.example.com/index.html$</literal></term>
2043 matches only the single document <literal>/index.html</literal>
2044 on <literal>www.example.com</literal>.
2049 <term><literal>/index.html$</literal></term>
2052 matches the document <literal>/index.html</literal>, regardless of the domain,
2053 i.e. on <emphasis>any</emphasis> web server anywhere.
2058 <term><literal>/</literal></term>
2061 Matches any URL because there's no requirement for either the
2062 domain or the path to match anything.
2067 <term><literal>:8000/</literal></term>
2070 Matches any URL pointing to TCP port 8000.
2075 <term><literal>10.0.0.1/</literal></term>
2078 Matches any URL with the host address <literal>10.0.0.1</literal>.
2079 (Note that the real URL uses plain brackets, not angle brackets.)
2084 <term><literal><2001:db8::1>/</literal></term>
2087 Matches any URL with the host address <literal>2001:db8::1</literal>.
2088 (Note that the real URL uses plain brackets, not angle brackets.)
2093 <term><literal>index.html</literal></term>
2096 matches nothing, since it would be interpreted as a domain name and
2097 there is no top-level domain called <literal>.html</literal>. So its
2105 <!-- ~~~~~ New section ~~~~~ -->
2106 <sect3 id="host-pattern"><title>The Host Pattern</title>
2109 The matching of the host part offers some flexible options: if the
2110 host pattern starts or ends with a dot, it becomes unanchored at that end.
2111 The host pattern is often referred to as domain pattern as it is usually
2112 used to match domain names and not IP addresses.
2118 <term><literal>.example.com</literal></term>
2121 matches any domain with first-level domain <literal>com</literal>
2122 and second-level domain <literal>example</literal>.
2123 For example <literal>www.example.com</literal>,
2124 <literal>example.com</literal> and <literal>foo.bar.baz.example.com</literal>.
2125 Note that it wouldn't match if the second-level domain was <literal>another-example</literal>.
2130 <term><literal>www.</literal></term>
2133 matches any domain that <emphasis>STARTS</emphasis> with
2134 <literal>www.</literal> (It also matches the domain
2135 <literal>www</literal> but most of the time that doesn't matter.)
2140 <term><literal>.example.</literal></term>
2143 matches any domain that <emphasis>CONTAINS</emphasis> <literal>.example.</literal>.
2144 And, by the way, also included would be any files or documents that exist
2145 within that domain since no path limitations are specified. (Correctly
2146 speaking: It matches any FQDN that contains <literal>example</literal> as
2147 a domain.) This might be <literal>www.example.com</literal>,
2148 <literal>news.example.de</literal>, or
2149 <literal>www.example.net/cgi/testing.pl</literal> for instance. All these
2157 Additionally, there are wild-cards that you can use in the domain names
2158 themselves. These work similarly to shell globbing type wild-cards:
2159 <quote>*</quote> represents zero or more arbitrary characters (this is
2161 <ulink url="http://en.wikipedia.org/wiki/Regular_expressions"><quote>Regular
2162 Expression</quote></ulink> based syntax of <quote>.*</quote>),
2163 <quote>?</quote> represents any single character (this is equivalent to the
2164 regular expression syntax of a simple <quote>.</quote>), and you can define
2165 <quote>character classes</quote> in square brackets which is similar to
2166 the same regular expression technique. All of this can be freely mixed:
2171 <term><literal>ad*.example.com</literal></term>
2174 matches <quote>adserver.example.com</quote>,
2175 <quote>ads.example.com</quote>, etc but not <quote>sfads.example.com</quote>
2180 <term><literal>*ad*.example.com</literal></term>
2183 matches all of the above, and then some.
2188 <term><literal>.?pix.com</literal></term>
2191 matches <literal>www.ipix.com</literal>,
2192 <literal>pictures.epix.com</literal>, <literal>a.b.c.d.e.upix.com</literal> etc.
2197 <term><literal>www[1-9a-ez].example.c*</literal></term>
2200 matches <literal>www1.example.com</literal>,
2201 <literal>www4.example.cc</literal>, <literal>wwwd.example.cy</literal>,
2202 <literal>wwwz.example.com</literal> etc., but <emphasis>not</emphasis>
2203 <literal>wwww.example.com</literal>.
2210 While flexible, this is not the sophistication of full regular expression based syntax.
2215 <!-- ~ End section ~ -->
2218 <!-- ~~~~~ New section ~~~~~ -->
2219 <sect3 id="path-pattern"><title>The Path Pattern</title>
2222 <application>Privoxy</application> uses <quote>modern</quote> POSIX 1003.2
2223 <ulink url="http://en.wikipedia.org/wiki/Regular_expressions"><quote>Regular
2224 Expressions</quote></ulink> for matching the path portion (after the slash),
2225 and is thus more flexible.
2229 There is an <link linkend="regex">Appendix</link> with a brief quick-start into regular
2230 expressions, you also might want to have a look at your operating system's documentation
2231 on regular expressions (try <literal>man re_format</literal>).
2235 Note that the path pattern is automatically left-anchored at the <quote>/</quote>,
2236 i.e. it matches as if it would start with a <quote>^</quote> (regular expression speak
2237 for the beginning of a line).
2241 Please also note that matching in the path is <emphasis>CASE INSENSITIVE</emphasis>
2242 by default, but you can switch to case sensitive at any point in the pattern by using the
2243 <quote>(?-i)</quote> switch: <literal>www.example.com/(?-i)PaTtErN.*</literal> will match
2244 only documents whose path starts with <literal>PaTtErN</literal> in
2245 <emphasis>exactly</emphasis> this capitalization.
2250 <term><literal>.example.com/.*</literal></term>
2253 Is equivalent to just <quote>.example.com</quote>, since any documents
2254 within that domain are matched with or without the <quote>.*</quote>
2255 regular expression. This is redundant
2260 <term><literal>.example.com/.*/index.html$</literal></term>
2263 Will match any page in the domain of <quote>example.com</quote> that is
2264 named <quote>index.html</quote>, and that is part of some path. For
2265 example, it matches <quote>www.example.com/testing/index.html</quote> but
2266 NOT <quote>www.example.com/index.html</quote> because the regular
2267 expression called for at least two <quote>/'s</quote>, thus the path
2268 requirement. It also would match
2269 <quote>www.example.com/testing/index_html</quote>, because of the
2270 special meta-character <quote>.</quote>.
2275 <term><literal>.example.com/(.*/)?index\.html$</literal></term>
2278 This regular expression is conditional so it will match any page
2279 named <quote>index.html</quote> regardless of path which in this case can
2280 have one or more <quote>/'s</quote>. And this one must contain exactly
2281 <quote>.html</quote> (but does not have to end with that!).
2286 <term><literal>.example.com/(.*/)(ads|banners?|junk)</literal></term>
2289 This regular expression will match any path of <quote>example.com</quote>
2290 that contains any of the words <quote>ads</quote>, <quote>banner</quote>,
2291 <quote>banners</quote> (because of the <quote>?</quote>) or <quote>junk</quote>.
2292 The path does not have to end in these words, just contain them.
2297 <term><literal>.example.com/(.*/)(ads|banners?|junk)/.*\.(jpe?g|gif|png)$</literal></term>
2300 This is very much the same as above, except now it must end in either
2301 <quote>.jpg</quote>, <quote>.jpeg</quote>, <quote>.gif</quote> or <quote>.png</quote>. So this
2302 one is limited to common image formats.
2309 There are many, many good examples to be found in <filename>default.action</filename>,
2310 and more tutorials below in <link linkend="regex">Appendix on regular expressions</link>.
2315 <!-- ~ End section ~ -->
2318 <!-- ~~~~~ New section ~~~~~ -->
2319 <sect3 id="tag-pattern"><title>The Request Tag Pattern</title>
2322 Request tag patterns are used to change the applying actions based on the
2323 request's tags. Tags can be created based on HTTP headers with either
2324 the <link linkend="CLIENT-HEADER-TAGGER">client-header-tagger</link>
2325 or the <link linkend="SERVER-HEADER-TAGGER">server-header-tagger</link> action.
2329 Request tag patterns have to start with <quote>TAG:</quote>, so &my-app;
2330 can tell them apart from other patterns. Everything after the colon
2331 including white space, is interpreted as a regular expression with
2332 path pattern syntax, except that tag patterns aren't left-anchored
2333 automatically (&my-app; doesn't silently add a <quote>^</quote>,
2334 you have to do it yourself if you need it).
2338 To match all requests that are tagged with <quote>foo</quote>
2339 your pattern line should be <quote>TAG:^foo$</quote>,
2340 <quote>TAG:foo</quote> would work as well, but it would also
2341 match requests whose tags contain <quote>foo</quote> somewhere.
2342 <quote>TAG: foo</quote> wouldn't work as it requires white space.
2346 Sections can contain URL and request tag patterns at the same time,
2347 but request tag patterns are checked after the URL patterns and thus
2348 always overrule them, even if they are located before the URL patterns.
2352 Once a new request tag is added, Privoxy checks right away if it's matched by one
2353 of the request tag patterns and updates the action settings accordingly. As a result
2354 request tags can be used to activate other tagger actions, as long as these other
2355 taggers look for headers that haven't already be parsed.
2359 For example you could tag client requests which use the
2360 <literal>POST</literal> method,
2361 then use this tag to activate another tagger that adds a tag if cookies
2362 are sent, and then use a block action based on the cookie tag. This allows
2363 the outcome of one action, to be input into a subsequent action. However if
2364 you'd reverse the position of the described taggers, and activated the
2365 method tagger based on the cookie tagger, no method tags would be created.
2366 The method tagger would look for the request line, but at the time
2367 the cookie tag is created, the request line has already been parsed.
2371 While this is a limitation you should be aware of, this kind of
2372 indirection is seldom needed anyway and even the example doesn't
2373 make too much sense.
2378 <!-- ~~~~~ New section ~~~~~ -->
2379 <sect3 id="negative-tag-patterns"><title>The Negative Request Tag Patterns</title>
2382 To match requests that do not have a certain request tag, specify a negative tag pattern
2383 by prefixing the tag pattern line with either <quote>NO-REQUEST-TAG:</quote>
2384 or <quote>NO-RESPONSE-TAG:</quote> instead of <quote>TAG:</quote>.
2388 Negative request tag patterns created with <quote>NO-REQUEST-TAG:</quote> are checked
2389 after all client headers are scanned, the ones created with <quote>NO-RESPONSE-TAG:</quote>
2390 are checked after all server headers are scanned. In both cases all the created
2391 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>
2453 <!-- ~ End section ~ -->
2456 <!-- ~~~~~ New section ~~~~~ -->
2458 <sect2 id="actions">
2459 <title>Actions</title>
2461 All actions are disabled by default, until they are explicitly enabled
2462 somewhere in an actions file. Actions are turned on if preceded with a
2463 <quote>+</quote>, and turned off if preceded with a <quote>-</quote>. So a
2464 <literal>+action</literal> means <quote>do that action</quote>, e.g.
2465 <literal>+block</literal> means <quote>please block URLs that match the
2466 following patterns</quote>, and <literal>-block</literal> means <quote>don't
2467 block URLs that match the following patterns, even if <literal>+block</literal>
2468 previously applied.</quote>
2473 Again, actions are invoked by placing them on a line, enclosed in curly braces and
2474 separated by whitespace, like in
2475 <literal>{+some-action -some-other-action{some-parameter}}</literal>,
2476 followed by a list of URL patterns, one per line, to which they apply.
2477 Together, the actions line and the following pattern lines make up a section
2478 of the actions file.
2482 Actions fall into three categories:
2489 Boolean, i.e the action can only be <quote>enabled</quote> or
2490 <quote>disabled</quote>. Syntax:
2494 +<replaceable class="function">name</replaceable> # enable action <replaceable class="parameter">name</replaceable>
2495 -<replaceable class="function">name</replaceable> # disable action <replaceable class="parameter">name</replaceable></screen>
2498 Example: <literal>+handle-as-image</literal>
2505 Parameterized, where some value is required in order to enable this type of action.
2510 +<replaceable class="function">name</replaceable>{<replaceable class="parameter">param</replaceable>} # enable action and set parameter to <replaceable class="parameter">param</replaceable>,
2511 # overwriting parameter from previous match if necessary
2512 -<replaceable class="function">name</replaceable> # disable action. The parameter can be omitted</screen>
2515 Note that if the URL matches multiple positive forms of a parameterized action,
2516 the last match wins, i.e. the params from earlier matches are simply ignored.
2519 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>
2525 Multi-value. These look exactly like parameterized actions,
2526 but they behave differently: If the action applies multiple times to the
2527 same URL, but with different parameters, <emphasis>all</emphasis> the parameters
2528 from <emphasis>all</emphasis> matches are remembered. This is used for actions
2529 that can be executed for the same request repeatedly, like adding multiple
2530 headers, or filtering through multiple filters. Syntax:
2534 +<replaceable class="function">name</replaceable>{<replaceable class="parameter">param</replaceable>} # enable action and add <replaceable class="parameter">param</replaceable> to the list of parameters
2535 -<replaceable class="function">name</replaceable>{<replaceable class="parameter">param</replaceable>} # remove the parameter <replaceable class="parameter">param</replaceable> from the list of parameters
2536 # If it was the last one left, disable the action.
2537 <replaceable class="parameter">-name</replaceable> # disable this action completely and remove all parameters from the list</screen>
2540 Examples: <literal>+add-header{X-Fun-Header: Some text}</literal> and
2541 <literal>+filter{html-annoyances}</literal>
2549 If nothing is specified in any actions file, no <quote>actions</quote> are
2550 taken. So in this case <application>Privoxy</application> would just be a
2551 normal, non-blocking, non-filtering proxy. You must specifically enable the
2552 privacy and blocking features you need (although the provided default actions
2553 files will give a good starting point).
2557 Later defined action sections always over-ride earlier ones of the same type.
2558 So exceptions to any rules you make, should come in the latter part of the file (or
2559 in a file that is processed later when using multiple actions files such
2560 as <filename>user.action</filename>). For multi-valued actions, the actions
2561 are applied in the order they are specified. Actions files are processed in
2562 the order they are defined in <filename>config</filename> (the default
2563 installation has three actions files). It also quite possible for any given
2564 URL to match more than one <quote>pattern</quote> (because of wildcards and
2565 regular expressions), and thus to trigger more than one set of actions! Last
2569 <!-- start actions listing -->
2571 The list of valid <application>Privoxy</application> actions are:
2575 <!-- ********************************************************** -->
2576 <!-- Please note the below defined actions use id's that are -->
2577 <!-- probably linked from other places, so please don't change. -->
2579 <!-- ********************************************************** -->
2582 <!-- ~~~~~ New section ~~~~~ -->
2584 <sect3 renderas="sect4" id="add-header">
2585 <title>add-header</title>
2589 <term>Typical use:</term>
2591 <para>Confuse log analysis, custom applications</para>
2596 <term>Effect:</term>
2599 Sends a user defined HTTP header to the web server.
2606 <!-- boolean, parameterized, Multi-value -->
2608 <para>Multi-value.</para>
2613 <term>Parameter:</term>
2616 Any string value is possible. Validity of the defined HTTP headers is not checked.
2617 It is recommended that you use the <quote><literal>X-</literal></quote> prefix
2627 This action may be specified multiple times, in order to define multiple
2628 headers. This is rarely needed for the typical user. If you don't know what
2629 <quote>HTTP headers</quote> are, you definitely don't need to worry about this
2633 Headers added by this action are not modified by other actions.
2639 <term>Example usage:</term>
2642 <screen># Add a DNT ("Do not track") header to all requests,
2643 # event to those that already have one.
2645 # This is just an example, not a recommendation.
2647 # There is no reason to believe that user-tracking websites care
2648 # about the DNT header and depending on the User-Agent, adding the
2649 # header may make user-tracking easier.
2650 {+add-header{DNT: 1}}
2659 <!-- ~~~~~ New section ~~~~~ -->
2660 <sect3 renderas="sect4" id="block">
2661 <title>block</title>
2665 <term>Typical use:</term>
2667 <para>Block ads or other unwanted content</para>
2672 <term>Effect:</term>
2675 Requests for URLs to which this action applies are blocked, i.e. the
2676 requests are trapped by &my-app; and the requested URL is never retrieved,
2677 but is answered locally with a substitute page or image, as determined by
2679 linkend="handle-as-image">handle-as-image</link></literal>,
2681 linkend="set-image-blocker">set-image-blocker</link></literal>, and
2683 linkend="handle-as-empty-document">handle-as-empty-document</link></literal> actions.
2691 <!-- boolean, parameterized, Multi-value -->
2693 <para>Parameterized.</para>
2698 <term>Parameter:</term>
2700 <para>A block reason that should be given to the user.</para>
2708 <application>Privoxy</application> sends a special <quote>BLOCKED</quote> page
2709 for requests to blocked pages. This page contains the block reason given as
2710 parameter, a link to find out why the block action applies, and a click-through
2711 to the blocked content (the latter only if the force feature is available and
2715 A very important exception occurs if <emphasis>both</emphasis>
2716 <literal>block</literal> and <literal><link linkend="handle-as-image">handle-as-image</link></literal>,
2717 apply to the same request: it will then be replaced by an image. If
2718 <literal><link linkend="set-image-blocker">set-image-blocker</link></literal>
2719 (see below) also applies, the type of image will be determined by its parameter,
2720 if not, the standard checkerboard pattern is sent.
2723 It is important to understand this process, in order
2724 to understand how <application>Privoxy</application> deals with
2725 ads and other unwanted content. Blocking is a core feature, and one
2726 upon which various other features depend.
2729 The <literal><link linkend="filter">filter</link></literal>
2730 action can perform a very similar task, by <quote>blocking</quote>
2731 banner images and other content through rewriting the relevant URLs in the
2732 document's HTML source, so they don't get requested in the first place.
2733 Note that this is a totally different technique, and it's easy to confuse the two.
2739 <term>Example usage (section):</term>
2742 <screen>{+block{No nasty stuff for you.}}
2743 # Block and replace with "blocked" page
2744 .nasty-stuff.example.com
2746 {+block{Doubleclick banners.} +handle-as-image}
2747 # Block and replace with image
2751 {+block{Layered ads.} +handle-as-empty-document}
2752 # Block and then ignore
2753 adserver.example.net/.*\.js$</screen>
2763 <!-- ~~~~~ New section ~~~~~ -->
2764 <sect3 renderas="sect4" id="change-x-forwarded-for">
2765 <title>change-x-forwarded-for</title>
2769 <term>Typical use:</term>
2771 <para>Improve privacy by not forwarding the source of the request in the HTTP headers.</para>
2776 <term>Effect:</term>
2779 Deletes the <quote>X-Forwarded-For:</quote> HTTP header from the client request,
2787 <!-- Boolean, Parameterized, Multi-value -->
2789 <para>Parameterized.</para>
2794 <term>Parameter:</term>
2798 <para><quote>block</quote> to delete the header.</para>
2802 <quote>add</quote> to create the header (or append
2803 the client's IP address to an already existing one).
2814 It is safe and recommended to use <literal>block</literal>.
2817 Forwarding the source address of the request may make
2818 sense in some multi-user setups but is also a privacy risk.
2823 <term>Example usage:</term>
2826 <screen>+change-x-forwarded-for{block}</screen>
2833 <!-- ~~~~~ New section ~~~~~ -->
2834 <sect3 renderas="sect4" id="client-header-filter">
2835 <title>client-header-filter</title>
2839 <term>Typical use:</term>
2842 Rewrite or remove single client headers.
2848 <term>Effect:</term>
2851 All client headers to which this action applies are filtered on-the-fly through
2852 the specified regular expression based substitutions.
2859 <!-- boolean, parameterized, Multi-value -->
2861 <para>Multi-value.</para>
2866 <term>Parameter:</term>
2869 The name of a client-header filter, as defined in one of the
2870 <link linkend="filter-file">filter files</link>.
2879 Client-header filters are applied to each header on its own, not to
2880 all at once. This makes it easier to diagnose problems, but on the downside
2881 you can't write filters that only change header x if header y's value is z.
2882 You can do that by using tags though.
2885 Client-header filters are executed after the other header actions have finished
2886 and use their output as input.
2889 If the request URI gets changed, &my-app; will detect that and use the new
2890 one. This can be used to rewrite the request destination behind the client's
2891 back, for example to specify a Tor exit relay for certain requests.
2894 Please refer to the <link linkend="filter-file">filter file chapter</link>
2895 to learn which client-header filters are available by default, and how to
2903 <term>Example usage (section):</term>
2907 # Hide Tor exit notation in Host and Referer Headers
2908 {+client-header-filter{hide-tor-exit-notation}}
2919 <!-- ~~~~~ New section ~~~~~ -->
2920 <sect3 renderas="sect4" id="client-header-tagger">
2921 <title>client-header-tagger</title>
2925 <term>Typical use:</term>
2928 Block requests based on their headers.
2934 <term>Effect:</term>
2937 Client headers to which this action applies are filtered on-the-fly through
2938 the specified regular expression based substitutions, the result is used as
2946 <!-- boolean, parameterized, Multi-value -->
2948 <para>Multi-value.</para>
2953 <term>Parameter:</term>
2956 The name of a client-header tagger, as defined in one of the
2957 <link linkend="filter-file">filter files</link>.
2966 Client-header taggers are applied to each header on its own,
2967 and as the header isn't modified, each tagger <quote>sees</quote>
2971 Client-header taggers are the first actions that are executed
2972 and their tags can be used to control every other action.
2978 <term>Example usage (section):</term>
2982 # Tag every request with the User-Agent header
2983 {+client-header-tagger{user-agent}}
2986 # Tagging itself doesn't change the action
2987 # settings, sections with TAG patterns do:
2989 # If it's a download agent, use a different forwarding proxy,
2990 # show the real User-Agent and make sure resume works.
2991 {+forward-override{forward-socks5 10.0.0.2:2222 .} \
2992 -hide-if-modified-since \
2993 -overwrite-last-modified \
2998 TAG:^User-Agent: NetBSD-ftp/
2999 TAG:^User-Agent: Novell ZYPP Installer
3000 TAG:^User-Agent: RPM APT-HTTP/
3001 TAG:^User-Agent: fetch libfetch/
3002 TAG:^User-Agent: Ubuntu APT-HTTP/
3003 TAG:^User-Agent: MPlayer/
3008 # Tag all requests with the Range header set
3009 {+client-header-tagger{range-requests}}
3012 # Disable filtering for the tagged requests.
3014 # With filtering enabled Privoxy would remove the Range headers
3015 # to be able to filter the whole response. The downside is that
3016 # it prevents clients from resuming downloads or skipping over
3017 # parts of multimedia files.
3018 {-filter -deanimate-gifs}
3029 <!-- ~~~~~ New section ~~~~~ -->
3030 <sect3 renderas="sect4" id="content-type-overwrite">
3031 <title>content-type-overwrite</title>
3035 <term>Typical use:</term>
3037 <para>Stop useless download menus from popping up, or change the browser's rendering mode</para>
3042 <term>Effect:</term>
3045 Replaces the <quote>Content-Type:</quote> HTTP server header.
3052 <!-- Boolean, Parameterized, Multi-value -->
3054 <para>Parameterized.</para>
3059 <term>Parameter:</term>
3071 The <quote>Content-Type:</quote> HTTP server header is used by the
3072 browser to decide what to do with the document. The value of this
3073 header can cause the browser to open a download menu instead of
3074 displaying the document by itself, even if the document's format is
3075 supported by the browser.
3078 The declared content type can also affect which rendering mode
3079 the browser chooses. If XHTML is delivered as <quote>text/html</quote>,
3080 many browsers treat it as yet another broken HTML document.
3081 If it is send as <quote>application/xml</quote>, browsers with
3082 XHTML support will only display it, if the syntax is correct.
3085 If you see a web site that proudly uses XHTML buttons, but sets
3086 <quote>Content-Type: text/html</quote>, you can use &my-app;
3087 to overwrite it with <quote>application/xml</quote> and validate
3088 the web master's claim inside your XHTML-supporting browser.
3089 If the syntax is incorrect, the browser will complain loudly.
3092 You can also go the opposite direction: if your browser prints
3093 error messages instead of rendering a document falsely declared
3094 as XHTML, you can overwrite the content type with
3095 <quote>text/html</quote> and have it rendered as broken HTML document.
3098 By default <literal>content-type-overwrite</literal> only replaces
3099 <quote>Content-Type:</quote> headers that look like some kind of text.
3100 If you want to overwrite it unconditionally, you have to combine it with
3101 <literal><link linkend="force-text-mode">force-text-mode</link></literal>.
3102 This limitation exists for a reason, think twice before circumventing it.
3105 Most of the time it's easier to replace this action with a custom
3106 <literal><link linkend="server-header-filter">server-header filter</link></literal>.
3107 It allows you to activate it for every document of a certain site and it will still
3108 only replace the content types you aimed at.
3111 Of course you can apply <literal>content-type-overwrite</literal>
3112 to a whole site and then make URL based exceptions, but it's a lot
3113 more work to get the same precision.
3119 <term>Example usage (sections):</term>
3122 <screen># Check if www.example.net/ really uses valid XHTML
3123 { +content-type-overwrite{application/xml} }
3126 # but leave the content type unmodified if the URL looks like a style sheet
3127 {-content-type-overwrite}
3128 www.example.net/.*\.css$
3129 www.example.net/.*style
3138 <!-- ~~~~~ New section ~~~~~ -->
3139 <sect3 renderas="sect4" id="crunch-client-header">
3143 <title>crunch-client-header</title>
3147 <term>Typical use:</term>
3149 <para>Remove a client header <application>Privoxy</application> has no dedicated action for.</para>
3154 <term>Effect:</term>
3157 Deletes every header sent by the client that contains the string the user supplied as parameter.
3164 <!-- Boolean, Parameterized, Multi-value -->
3166 <para>Parameterized.</para>
3171 <term>Parameter:</term>
3183 This action allows you to block client headers for which no dedicated
3184 <application>Privoxy</application> action exists.
3185 <application>Privoxy</application> will remove every client header that
3186 contains the string you supplied as parameter.
3189 Regular expressions are <emphasis>not supported</emphasis> and you can't
3190 use this action to block different headers in the same request, unless
3191 they contain the same string.
3194 <literal>crunch-client-header</literal> is only meant for quick tests.
3195 If you have to block several different headers, or only want to modify
3196 parts of them, you should use a
3197 <literal><link linkend="client-header-filter">client-header filter</link></literal>.
3201 Don't block any header without understanding the consequences.
3208 <term>Example usage (section):</term>
3211 <screen># Block the non-existent "Privacy-Violation:" client header
3212 { +crunch-client-header{Privacy-Violation:} }
3222 <!-- ~~~~~ New section ~~~~~ -->
3223 <sect3 renderas="sect4" id="crunch-if-none-match">
3224 <title>crunch-if-none-match</title>
3230 <term>Typical use:</term>
3232 <para>Prevent yet another way to track the user's steps between sessions.</para>
3237 <term>Effect:</term>
3240 Deletes the <quote>If-None-Match:</quote> HTTP client header.
3247 <!-- Boolean, Parameterized, Multi-value -->
3249 <para>Boolean.</para>
3254 <term>Parameter:</term>
3266 Removing the <quote>If-None-Match:</quote> HTTP client header
3267 is useful for filter testing, where you want to force a real
3268 reload instead of getting status code <quote>304</quote> which
3269 would cause the browser to use a cached copy of the page.
3272 It is also useful to make sure the header isn't used as a cookie
3273 replacement (unlikely but possible).
3276 Blocking the <quote>If-None-Match:</quote> header shouldn't cause any
3277 caching problems, as long as the <quote>If-Modified-Since:</quote> header
3278 isn't blocked or missing as well.
3281 It is recommended to use this action together with
3282 <literal><link linkend="hide-if-modified-since">hide-if-modified-since</link></literal>
3284 <literal><link linkend="overwrite-last-modified">overwrite-last-modified</link></literal>.
3290 <term>Example usage (section):</term>
3293 <screen># Let the browser revalidate cached documents but don't
3294 # allow the server to use the revalidation headers for user tracking.
3295 {+hide-if-modified-since{-60} \
3296 +overwrite-last-modified{randomize} \
3297 +crunch-if-none-match}
3306 <!-- ~~~~~ New section ~~~~~ -->
3307 <sect3 renderas="sect4" id="crunch-incoming-cookies">
3308 <title>crunch-incoming-cookies</title>
3312 <term>Typical use:</term>
3315 Prevent the web server from setting HTTP cookies on your system
3321 <term>Effect:</term>
3324 Deletes any <quote>Set-Cookie:</quote> HTTP headers from server replies.
3331 <!-- Boolean, Parameterized, Multi-value -->
3333 <para>Boolean.</para>
3338 <term>Parameter:</term>
3350 This action is only concerned with <emphasis>incoming</emphasis> HTTP cookies. For
3351 <emphasis>outgoing</emphasis> HTTP cookies, use
3352 <literal><link linkend="crunch-outgoing-cookies">crunch-outgoing-cookies</link></literal>.
3353 Use <emphasis>both</emphasis> to disable HTTP cookies completely.
3356 It makes <emphasis>no sense at all</emphasis> to use this action in conjunction
3357 with the <literal><link linkend="session-cookies-only">session-cookies-only</link></literal> action,
3358 since it would prevent the session cookies from being set. See also
3359 <literal><link linkend="filter-content-cookies">filter-content-cookies</link></literal>.
3365 <term>Example usage:</term>
3368 <screen>+crunch-incoming-cookies</screen>
3376 <!-- ~~~~~ New section ~~~~~ -->
3377 <sect3 renderas="sect4" id="crunch-server-header">
3378 <title>crunch-server-header</title>
3384 <term>Typical use:</term>
3386 <para>Remove a server header <application>Privoxy</application> has no dedicated action for.</para>
3391 <term>Effect:</term>
3394 Deletes every header sent by the server that contains the string the user supplied as parameter.
3401 <!-- Boolean, Parameterized, Multi-value -->
3403 <para>Parameterized.</para>
3408 <term>Parameter:</term>
3420 This action allows you to block server headers for which no dedicated
3421 <application>Privoxy</application> action exists. <application>Privoxy</application>
3422 will remove every server header that contains the string you supplied as parameter.
3425 Regular expressions are <emphasis>not supported</emphasis> and you can't
3426 use this action to block different headers in the same request, unless
3427 they contain the same string.
3430 <literal>crunch-server-header</literal> is only meant for quick tests.
3431 If you have to block several different headers, or only want to modify
3432 parts of them, you should use a custom
3433 <literal><link linkend="server-header-filter">server-header filter</link></literal>.
3437 Don't block any header without understanding the consequences.
3444 <term>Example usage (section):</term>
3447 <screen># Crunch server headers that try to prevent caching
3448 { +crunch-server-header{no-cache} }
3457 <!-- ~~~~~ New section ~~~~~ -->
3458 <sect3 renderas="sect4" id="crunch-outgoing-cookies">
3459 <title>crunch-outgoing-cookies</title>
3463 <term>Typical use:</term>
3466 Prevent the web server from reading any HTTP cookies from your system
3472 <term>Effect:</term>
3475 Deletes any <quote>Cookie:</quote> HTTP headers from client requests.
3482 <!-- Boolean, Parameterized, Multi-value -->
3484 <para>Boolean.</para>
3489 <term>Parameter:</term>
3501 This action is only concerned with <emphasis>outgoing</emphasis> HTTP cookies. For
3502 <emphasis>incoming</emphasis> HTTP cookies, use
3503 <literal><link linkend="crunch-incoming-cookies">crunch-incoming-cookies</link></literal>.
3504 Use <emphasis>both</emphasis> to disable HTTP cookies completely.
3507 It makes <emphasis>no sense at all</emphasis> to use this action in conjunction
3508 with the <literal><link linkend="session-cookies-only">session-cookies-only</link></literal> action,
3509 since it would prevent the session cookies from being read.
3515 <term>Example usage:</term>
3518 <screen>+crunch-outgoing-cookies</screen>
3527 <!-- ~~~~~ New section ~~~~~ -->
3528 <sect3 renderas="sect4" id="deanimate-gifs">
3529 <title>deanimate-gifs</title>
3533 <term>Typical use:</term>
3535 <para>Stop those annoying, distracting animated GIF images.</para>
3540 <term>Effect:</term>
3543 De-animate GIF animations, i.e. reduce them to their first or last image.
3550 <!-- boolean, parameterized, Multi-value -->
3552 <para>Parameterized.</para>
3557 <term>Parameter:</term>
3560 <quote>last</quote> or <quote>first</quote>
3569 This will also shrink the images considerably (in bytes, not pixels!). If
3570 the option <quote>first</quote> is given, the first frame of the animation
3571 is used as the replacement. If <quote>last</quote> is given, the last
3572 frame of the animation is used instead, which probably makes more sense for
3573 most banner animations, but also has the risk of not showing the entire
3574 last frame (if it is only a delta to an earlier frame).
3577 You can safely use this action with patterns that will also match non-GIF
3578 objects, because no attempt will be made at anything that doesn't look like
3585 <term>Example usage:</term>
3588 <screen>+deanimate-gifs{last}</screen>
3595 <!-- ~~~~~ New section ~~~~~ -->
3596 <sect3 renderas="sect4" id="downgrade-http-version">
3597 <title>downgrade-http-version</title>
3601 <term>Typical use:</term>
3603 <para>Work around (very rare) problems with HTTP/1.1</para>
3608 <term>Effect:</term>
3611 Downgrades HTTP/1.1 client requests and server replies to HTTP/1.0.
3618 <!-- boolean, parameterized, Multi-value -->
3620 <para>Boolean.</para>
3625 <term>Parameter:</term>
3637 This is a left-over from the time when <application>Privoxy</application>
3638 didn't support important HTTP/1.1 features well. It is left here for the
3639 unlikely case that you experience HTTP/1.1-related problems with some server
3643 Note that enabling this action is only a workaround. It should not
3644 be enabled for sites that work without it. While it shouldn't break
3645 any pages, it has an (usually negative) performance impact.
3648 If you come across a site where enabling this action helps, please report it,
3649 so the cause of the problem can be analyzed. If the problem turns out to be
3650 caused by a bug in <application>Privoxy</application> it should be
3651 fixed so the following release works without the work around.
3657 <term>Example usage (section):</term>
3660 <screen>{+downgrade-http-version}
3661 problem-host.example.com</screen>
3669 <!-- ~~~~~ New section ~~~~~ -->
3670 <sect3 renderas="sect4" id="external-filter">
3671 <title>external-filter</title>
3675 <term>Typical use:</term>
3677 <para>Modify content using a programming language of your choice.</para>
3682 <term>Effect:</term>
3685 All instances of text-based type, most notably HTML and JavaScript, to which
3686 this action applies, can be filtered on-the-fly through the specified external
3688 By default plain text documents are exempted from filtering, because web
3689 servers often use the <literal>text/plain</literal> MIME type for all files
3690 whose type they don't know.)
3697 <!-- boolean, parameterized, Multi-value -->
3699 <para>Multi-value.</para>
3704 <term>Parameter:</term>
3707 The name of an external content filter, as defined in the
3708 <link linkend="filter-file">filter file</link>.
3709 External filters can be defined in one or more files as defined by the
3710 <literal><link linkend="filterfile">filterfile</link></literal>
3711 option in the <link linkend="config">config file</link>.
3714 When used in its negative form,
3715 and without parameters, <emphasis>all</emphasis> filtering with external
3716 filters is completely disabled.
3725 External filters are scripts or programs that can modify the content in
3726 case common <literal><link linkend="filter">filters</link></literal>
3727 aren't powerful enough. With the exception that this action doesn't
3728 use pcrs-based filters, the notes in the
3729 <literal><link linkend="filter">filter</link></literal> section apply.
3733 Currently external filters are executed with &my-app;'s privileges.
3734 Only use external filters you understand and trust.
3738 This feature is experimental, the <literal><link
3739 linkend="external-filter-syntax">syntax</link></literal>
3740 may change in the future.
3747 <term>Example usage:</term>
3750 <screen>+external-filter{fancy-filter}</screen>
3757 <!-- ~~~~~ New section ~~~~~ -->
3758 <sect3 renderas="sect4" id="fast-redirects">
3759 <title>fast-redirects</title>
3763 <term>Typical use:</term>
3765 <para>Fool some click-tracking scripts and speed up indirect links.</para>
3770 <term>Effect:</term>
3773 Detects redirection URLs and redirects the browser without contacting
3774 the redirection server first.
3781 <!-- boolean, parameterized, Multi-value -->
3783 <para>Parameterized.</para>
3788 <term>Parameter:</term>
3793 <quote>simple-check</quote> to just search for the string <quote>http://</quote>
3794 to detect redirection URLs.
3799 <quote>check-decoded-url</quote> to decode URLs (if necessary) before searching
3800 for redirection URLs.
3811 Many sites, like yahoo.com, don't just link to other sites. Instead, they
3812 will link to some script on their own servers, giving the destination as a
3813 parameter, which will then redirect you to the final target. URLs
3814 resulting from this scheme typically look like:
3815 <quote>http://www.example.org/click-tracker.cgi?target=http%3a//www.example.net/</quote>.
3818 Sometimes, there are even multiple consecutive redirects encoded in the
3819 URL. These redirections via scripts make your web browsing more traceable,
3820 since the server from which you follow such a link can see where you go
3821 to. Apart from that, valuable bandwidth and time is wasted, while your
3822 browser asks the server for one redirect after the other. Plus, it feeds
3826 This feature is currently not very smart and is scheduled for improvement.
3827 If it is enabled by default, you will have to create some exceptions to
3828 this action. It can lead to failures in several ways:
3831 Not every URLs with other URLs as parameters is evil.
3832 Some sites offer a real service that requires this information to work.
3833 For example a validation service needs to know, which document to validate.
3834 <literal>fast-redirects</literal> assumes that every URL parameter that
3835 looks like another URL is a redirection target, and will always redirect to
3836 the last one. Most of the time the assumption is correct, but if it isn't,
3837 the user gets redirected anyway.
3840 Another failure occurs if the URL contains other parameters after the URL parameter.
3842 <quote>http://www.example.org/?redirect=http%3a//www.example.net/&foo=bar</quote>.
3843 contains the redirection URL <quote>http://www.example.net/</quote>,
3844 followed by another parameter. <literal>fast-redirects</literal> doesn't know that
3845 and will cause a redirect to <quote>http://www.example.net/&foo=bar</quote>.
3846 Depending on the target server configuration, the parameter will be silently ignored
3847 or lead to a <quote>page not found</quote> error. You can prevent this problem by
3848 first using the <literal><link linkend="redirect">redirect</link></literal> action
3849 to remove the last part of the URL, but it requires a little effort.
3852 To detect a redirection URL, <literal>fast-redirects</literal> only
3853 looks for the string <quote>http://</quote>, either in plain text
3854 (invalid but often used) or encoded as <quote>http%3a//</quote>.
3855 Some sites use their own URL encoding scheme, encrypt the address
3856 of the target server or replace it with a database id. In theses cases
3857 <literal>fast-redirects</literal> is fooled and the request reaches the
3858 redirection server where it probably gets logged.
3864 <term>Example usage:</term>
3868 { +fast-redirects{simple-check} }
3871 { +fast-redirects{check-decoded-url} }
3872 another.example.com/testing</screen>
3881 <!-- ~~~~~ New section ~~~~~ -->
3882 <sect3 renderas="sect4" id="filter">
3883 <title>filter</title>
3887 <term>Typical use:</term>
3889 <para>Get rid of HTML and JavaScript annoyances, banner advertisements (by size),
3890 do fun text replacements, add personalized effects, etc.</para>
3895 <term>Effect:</term>
3898 All instances of text-based type, most notably HTML and JavaScript, to which
3899 this action applies, can be filtered on-the-fly through the specified regular
3900 expression based substitutions. (Note: as of version 3.0.3 plain text documents
3901 are exempted from filtering, because web servers often use the
3902 <literal>text/plain</literal> MIME type for all files whose type they don't know.)
3909 <!-- boolean, parameterized, Multi-value -->
3911 <para>Multi-value.</para>
3916 <term>Parameter:</term>
3919 The name of a content filter, as defined in the <link linkend="filter-file">filter file</link>.
3920 Filters can be defined in one or more files as defined by the
3921 <literal><link linkend="filterfile">filterfile</link></literal>
3922 option in the <link linkend="config">config file</link>.
3923 <filename>default.filter</filename> is the collection of filters
3924 supplied by the developers. Locally defined filters should go
3925 in their own file, such as <filename>user.filter</filename>.
3928 When used in its negative form,
3929 and without parameters, <emphasis>all</emphasis> filtering is completely disabled.
3938 For your convenience, there are a number of pre-defined filters available
3939 in the distribution filter file that you can use. See the examples below for
3943 Filtering requires buffering the page content, which may appear to
3944 slow down page rendering since nothing is displayed until all content has
3945 passed the filters. (The total time until the page is completely rendered
3946 doesn't change much, but it may be perceived as slower since the page is
3947 not incrementally displayed.)
3948 This effect will be more noticeable on slower connections.
3951 <quote>Rolling your own</quote>
3952 filters requires a knowledge of
3953 <ulink url="http://en.wikipedia.org/wiki/Regular_expressions"><quote>Regular
3954 Expressions</quote></ulink> and
3955 <ulink url="http://en.wikipedia.org/wiki/Html"><quote>HTML</quote></ulink>.
3956 This is very powerful feature, and potentially very intrusive.
3957 Filters should be used with caution, and where an equivalent
3958 <quote>action</quote> is not available.
3961 The amount of data that can be filtered is limited to the
3962 <literal><link linkend="buffer-limit">buffer-limit</link></literal>
3963 option in the main <link linkend="config">config file</link>. The
3964 default is 4096 KB (4 Megs). Once this limit is exceeded, the buffered
3965 data, and all pending data, is passed through unfiltered.
3968 Inappropriate MIME types, such as zipped files, are not filtered at all.
3969 (Again, only text-based types except plain text). Encrypted SSL data
3970 (from HTTPS servers) cannot be filtered either, since this would violate
3971 the integrity of the secure transaction. In some situations it might
3972 be necessary to protect certain text, like source code, from filtering
3973 by defining appropriate <literal>-filter</literal> exceptions.
3976 Compressed content can't be filtered either, but if &my-app;
3977 is compiled with zlib support and a supported compression algorithm
3978 is used (gzip or deflate), &my-app; can first decompress the content
3982 If you use a &my-app; version without zlib support, but want filtering to work on
3983 as much documents as possible, even those that would normally be sent compressed,
3984 you must use the <literal><link linkend="prevent-compression">prevent-compression</link></literal>
3985 action in conjunction with <literal>filter</literal>.
3988 Content filtering can achieve some of the same effects as the
3989 <literal><link linkend="block">block</link></literal>
3990 action, i.e. it can be used to block ads and banners. But the mechanism
3991 works quite differently. One effective use, is to block ad banners
3992 based on their size (see below), since many of these seem to be somewhat
3996 <link linkend="contact">Feedback</link> with suggestions for new or
3997 improved filters is particularly welcome!
4000 The below list has only the names and a one-line description of each
4001 predefined filter. There are <link linkend="predefined-filters">more
4002 verbose explanations</link> of what these filters do in the <link
4003 linkend="filter-file">filter file chapter</link>.
4009 <term>Example usage (with filters from the distribution <filename>default.filter</filename> file).
4010 See <link linkend="PREDEFINED-FILTERS">the Predefined Filters section</link> for
4011 more explanation on each:</term>
4014 <anchor id="filter-js-annoyances">
4015 <screen>+filter{js-annoyances} # Get rid of particularly annoying JavaScript abuse.</screen>
4018 <anchor id="filter-js-events">
4019 <screen>+filter{js-events} # Kill JavaScript event bindings and timers (Radically destructive! Only for extra nasty sites).</screen>
4022 <anchor id="filter-html-annoyances">
4023 <screen>+filter{html-annoyances} # Get rid of particularly annoying HTML abuse.</screen>
4026 <anchor id="filter-content-cookies">
4027 <screen>+filter{content-cookies} # Kill cookies that come in the HTML or JS content.</screen>
4030 <anchor id="filter-refresh-tags">
4031 <screen>+filter{refresh-tags} # Kill automatic refresh tags if refresh time is larger than 9 seconds.</screen>
4034 <anchor id="filter-unsolicited-popups">
4035 <screen>+filter{unsolicited-popups} # Disable only unsolicited pop-up windows.</screen>
4038 <anchor id="filter-all-popups">
4039 <screen>+filter{all-popups} # Kill all popups in JavaScript and HTML.</screen>
4042 <anchor id="filter-img-reorder">
4043 <screen>+filter{img-reorder} # Reorder attributes in <img> tags to make the banners-by-* filters more effective.</screen>
4046 <anchor id="filter-banners-by-size">
4047 <screen>+filter{banners-by-size} # Kill banners by size.</screen>
4050 <anchor id="filter-banners-by-link">
4051 <screen>+filter{banners-by-link} # Kill banners by their links to known clicktrackers.</screen>
4054 <anchor id="filter-webbugs">
4055 <screen>+filter{webbugs} # Squish WebBugs (1x1 invisible GIFs used for user tracking).</screen>
4058 <anchor id="filter-tiny-textforms">
4059 <screen>+filter{tiny-textforms} # Extend those tiny textareas up to 40x80 and kill the hard wrap.</screen>
4062 <anchor id="filter-jumping-windows">
4063 <screen>+filter{jumping-windows} # Prevent windows from resizing and moving themselves.</screen>
4066 <anchor id="filter-frameset-borders">
4067 <screen>+filter{frameset-borders} # Give frames a border and make them resizable.</screen>
4070 <anchor id="filter-iframes">
4071 <screen>+filter{iframes} # Removes all detected iframes. Should only be enabled for individual sites.</screen>
4074 <anchor id="filter-demoronizer">
4075 <screen>+filter{demoronizer} # Fix MS's non-standard use of standard charsets.</screen>
4078 <anchor id="filter-shockwave-flash">
4079 <screen>+filter{shockwave-flash} # Kill embedded Shockwave Flash objects.</screen>
4082 <anchor id="filter-quicktime-kioskmode">
4083 <screen>+filter{quicktime-kioskmode} # Make Quicktime movies saveable.</screen>
4086 <anchor id="filter-fun">
4087 <screen>+filter{fun} # Text replacements for subversive browsing fun!</screen>
4090 <anchor id="filter-crude-parental">
4091 <screen>+filter{crude-parental} # Crude parental filtering. Note that this filter doesn't work reliably.</screen>
4094 <anchor id="filter-ie-exploits">
4095 <screen>+filter{ie-exploits} # Disable some known Internet Explorer bug exploits.</screen>
4098 <anchor id="filter-site-specifics">
4099 <screen>+filter{site-specifics} # Cure for site-specific problems. Don't apply generally!</screen>
4102 <anchor id="filter-no-ping">
4103 <screen>+filter{no-ping} # Removes non-standard ping attributes in <a> and <area> tags.</screen>
4106 <anchor id="filter-google">
4107 <screen>+filter{google} # CSS-based block for Google text ads. Also removes a width limitation and the toolbar advertisement.</screen>
4110 <anchor id="filter-yahoo">
4111 <screen>+filter{yahoo} # CSS-based block for Yahoo text ads. Also removes a width limitation.</screen>
4114 <anchor id="filter-msn">
4115 <screen>+filter{msn} # CSS-based block for MSN text ads. Also removes tracking URLs and a width limitation.</screen>
4118 <anchor id="filter-blogspot">
4119 <screen>+filter{blogspot} # Cleans up some Blogspot blogs. Read the fine print before using this.</screen>
4127 <!-- ~~~~~ New section ~~~~~ -->
4128 <sect3 renderas="sect4" id="force-text-mode">
4129 <title>force-text-mode</title>
4135 <term>Typical use:</term>
4137 <para>Force <application>Privoxy</application> to treat a document as if it was in some kind of <emphasis>text</emphasis> format. </para>
4142 <term>Effect:</term>
4145 Declares a document as text, even if the <quote>Content-Type:</quote> isn't detected as such.
4152 <!-- Boolean, Parameterized, Multi-value -->
4154 <para>Boolean.</para>
4159 <term>Parameter:</term>
4171 As explained <literal><link linkend="filter">above</link></literal>,
4172 <application>Privoxy</application> tries to only filter files that are
4173 in some kind of text format. The same restrictions apply to
4174 <literal><link linkend="content-type-overwrite">content-type-overwrite</link></literal>.
4175 <literal>force-text-mode</literal> declares a document as text,
4176 without looking at the <quote>Content-Type:</quote> first.
4180 Think twice before activating this action. Filtering binary data
4181 with regular expressions can cause file damage.
4188 <term>Example usage:</term>
4201 <!-- ~~~~~ New section ~~~~~ -->
4202 <sect3 renderas="sect4" id="forward-override">
4203 <title>forward-override</title>
4209 <term>Typical use:</term>
4211 <para>Change the forwarding settings based on User-Agent or request origin</para>
4216 <term>Effect:</term>
4219 Overrules the forward directives in the configuration file.
4226 <!-- Boolean, Parameterized, Multi-value -->
4228 <para>Parameterized.</para>
4233 <term>Parameter:</term>
4237 <para><quote>forward .</quote> to use a direct connection without any additional proxies.</para>
4241 <quote>forward 127.0.0.1:8123</quote> to use the HTTP proxy listening at 127.0.0.1 port 8123.
4246 <quote>forward-socks4a 127.0.0.1:9050 .</quote> to use the socks4a proxy listening at
4247 127.0.0.1 port 9050. Replace <quote>forward-socks4a</quote> with <quote>forward-socks4</quote>
4248 to use a socks4 connection (with local DNS resolution) instead, use <quote>forward-socks5</quote>
4249 for socks5 connections (with remote DNS resolution).
4254 <quote>forward-socks4a 127.0.0.1:9050 proxy.example.org:8000</quote> to use the socks4a proxy
4255 listening at 127.0.0.1 port 9050 to reach the HTTP proxy listening at proxy.example.org port 8000.
4256 Replace <quote>forward-socks4a</quote> with <quote>forward-socks4</quote> to use a socks4 connection
4257 (with local DNS resolution) instead, use <quote>forward-socks5</quote>
4258 for socks5 connections (with remote DNS resolution).
4263 <quote>forward-webserver 127.0.0.1:80</quote> to use the HTTP
4264 server listening at 127.0.0.1 port 80 without adjusting the
4268 This makes it more convenient to use Privoxy to make
4269 existing websites available as onion services as well.
4272 Many websites serve content with hardcoded URLs and
4273 can't be easily adjusted to change the domain based
4274 on the one used by the client.
4277 Putting Privoxy between Tor and the webserver (or an stunnel
4278 that forwards to the webserver) allows to rewrite headers and
4279 content to make client and server happy at the same time.
4282 Using Privoxy for webservers that are only reachable through
4283 onion addresses and whose location is supposed to be secret
4284 is not recommended and should not be necessary anyway.
4295 This action takes parameters similar to the
4296 <link linkend="forwarding">forward</link> directives in the configuration
4297 file, but without the URL pattern. It can be used as replacement, but normally it's only
4298 used in cases where matching based on the request URL isn't sufficient.
4302 Please read the description for the <link linkend="forwarding">forward</link> directives before
4303 using this action. Forwarding to the wrong people will reduce your privacy and increase the
4304 chances of man-in-the-middle attacks.
4307 If the ports are missing or invalid, default values will be used. This might change
4308 in the future and you shouldn't rely on it. Otherwise incorrect syntax causes Privoxy
4309 to exit. Due to design limitations, invalid parameter syntax isn't detected until the
4310 action is used the first time.
4313 Use the <ulink url="http://config.privoxy.org/show-url-info">show-url-info CGI page</ulink>
4314 to verify that your forward settings do what you thought the do.
4321 <term>Example usage:</term>
4325 # Use an ssh tunnel for requests previously tagged as
4326 # <quote>User-Agent: fetch libfetch/2.0</quote> and make sure
4327 # resuming downloads continues to work.
4329 # This way you can continue to use Tor for your normal browsing,
4330 # without overloading the Tor network with your FreeBSD ports updates
4331 # or downloads of bigger files like ISOs.
4333 # Note that HTTP headers are easy to fake and therefore their
4334 # values are as (un)trustworthy as your clients and users.
4335 {+forward-override{forward-socks5 10.0.0.2:2222 .} \
4336 -hide-if-modified-since \
4337 -overwrite-last-modified \
4339 TAG:^User-Agent: fetch libfetch/2\.0$
4348 <!-- ~~~~~ New section ~~~~~ -->
4349 <sect3 renderas="sect4" id="handle-as-empty-document">
4350 <title>handle-as-empty-document</title>
4356 <term>Typical use:</term>
4358 <para>Mark URLs that should be replaced by empty documents <emphasis>if they get blocked</emphasis></para>
4363 <term>Effect:</term>
4366 This action alone doesn't do anything noticeable. It just marks URLs.
4367 If the <literal><link linkend="block">block</link></literal> action <emphasis>also applies</emphasis>,
4368 the presence or absence of this mark decides whether an HTML <quote>BLOCKED</quote>
4369 page, or an empty document will be sent to the client as a substitute for the blocked content.
4370 The <emphasis>empty</emphasis> document isn't literally empty, but actually contains a single space.
4377 <!-- Boolean, Parameterized, Multi-value -->
4379 <para>Boolean.</para>
4384 <term>Parameter:</term>
4396 Some browsers complain about syntax errors if JavaScript documents
4397 are blocked with <application>Privoxy's</application>
4398 default HTML page; this option can be used to silence them.
4399 And of course this action can also be used to eliminate the &my-app;
4400 BLOCKED message in frames.
4403 The content type for the empty document can be specified with
4404 <literal><link linkend="content-type-overwrite">content-type-overwrite{}</link></literal>,
4405 but usually this isn't necessary.
4411 <term>Example usage:</term>
4414 <screen># Block all documents on example.org that end with ".js",
4415 # but send an empty document instead of the usual HTML message.
4416 {+block{Blocked JavaScript} +handle-as-empty-document}
4426 <!-- ~~~~~ New section ~~~~~ -->
4427 <sect3 renderas="sect4" id="handle-as-image">
4428 <title>handle-as-image</title>
4432 <term>Typical use:</term>
4434 <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>
4439 <term>Effect:</term>
4442 This action alone doesn't do anything noticeable. It just marks URLs as images.
4443 If the <literal><link linkend="block">block</link></literal> action <emphasis>also applies</emphasis>,
4444 the presence or absence of this mark decides whether an HTML <quote>blocked</quote>
4445 page, or a replacement image (as determined by the <literal><link
4446 linkend="set-image-blocker">set-image-blocker</link></literal> action) will be sent to the
4447 client as a substitute for the blocked content.
4454 <!-- Boolean, Parameterized, Multi-value -->
4456 <para>Boolean.</para>
4461 <term>Parameter:</term>
4473 The below generic example section is actually part of <filename>default.action</filename>.
4474 It marks all URLs with well-known image file name extensions as images and should
4478 Users will probably only want to use the handle-as-image action in conjunction with
4479 <literal><link linkend="block">block</link></literal>, to block sources of banners, whose URLs don't
4480 reflect the file type, like in the second example section.
4483 Note that you cannot treat HTML pages as images in most cases. For instance, (in-line) ad
4484 frames require an HTML page to be sent, or they won't display properly.
4485 Forcing <literal>handle-as-image</literal> in this situation will not replace the
4486 ad frame with an image, but lead to error messages.
4492 <term>Example usage (sections):</term>
4495 <screen># Generic image extensions:
4498 /.*\.(gif|jpg|jpeg|png|bmp|ico)$
4500 # These don't look like images, but they're banners and should be
4501 # blocked as images:
4503 {+block{Nasty banners.} +handle-as-image}
4504 nasty-banner-server.example.com/junk.cgi\?output=trash
4513 <!-- ~~~~~ New section ~~~~~ -->
4514 <sect3 renderas="sect4" id="hide-accept-language">
4515 <title>hide-accept-language</title>
4521 <term>Typical use:</term>
4523 <para>Pretend to use different language settings.</para>
4528 <term>Effect:</term>
4531 Deletes or replaces the <quote>Accept-Language:</quote> HTTP header in client requests.
4538 <!-- Boolean, Parameterized, Multi-value -->
4540 <para>Parameterized.</para>
4545 <term>Parameter:</term>
4548 Keyword: <quote>block</quote>, or any user defined value.
4557 Faking the browser's language settings can be useful to make a
4558 foreign User-Agent set with
4559 <literal><link linkend="hide-user-agent">hide-user-agent</link></literal>
4563 However some sites with content in different languages check the
4564 <quote>Accept-Language:</quote> to decide which one to take by default.
4565 Sometimes it isn't possible to later switch to another language without
4566 changing the <quote>Accept-Language:</quote> header first.
4569 Therefore it's a good idea to either only change the
4570 <quote>Accept-Language:</quote> header to languages you understand,
4571 or to languages that aren't wide spread.
4574 Before setting the <quote>Accept-Language:</quote> header
4575 to a rare language, you should consider that it helps to
4576 make your requests unique and thus easier to trace.
4577 If you don't plan to change this header frequently,
4578 you should stick to a common language.
4584 <term>Example usage (section):</term>
4587 <screen># Pretend to use Canadian language settings.
4588 {+hide-accept-language{en-ca} \
4589 +hide-user-agent{Mozilla/5.0 (X11; U; OpenBSD i386; en-CA; rv:1.8.0.4) Gecko/20060628 Firefox/1.5.0.4} \
4599 <!-- ~~~~~ New section ~~~~~ -->
4600 <sect3 renderas="sect4" id="hide-content-disposition">
4601 <title>hide-content-disposition</title>
4607 <term>Typical use:</term>
4609 <para>Prevent download menus for content you prefer to view inside the browser.</para>
4614 <term>Effect:</term>
4617 Deletes or replaces the <quote>Content-Disposition:</quote> HTTP header set by some servers.
4624 <!-- Boolean, Parameterized, Multi-value -->
4626 <para>Parameterized.</para>
4631 <term>Parameter:</term>
4634 Keyword: <quote>block</quote>, or any user defined value.
4643 Some servers set the <quote>Content-Disposition:</quote> HTTP header for
4644 documents they assume you want to save locally before viewing them.
4645 The <quote>Content-Disposition:</quote> header contains the file name
4646 the browser is supposed to use by default.
4649 In most browsers that understand this header, it makes it impossible to
4650 <emphasis>just view</emphasis> the document, without downloading it first,
4651 even if it's just a simple text file or an image.
4654 Removing the <quote>Content-Disposition:</quote> header helps
4655 to prevent this annoyance, but some browsers additionally check the
4656 <quote>Content-Type:</quote> header, before they decide if they can
4657 display a document without saving it first. In these cases, you have
4658 to change this header as well, before the browser stops displaying
4662 It is also possible to change the server's file name suggestion
4663 to another one, but in most cases it isn't worth the time to set
4667 This action will probably be removed in the future,
4668 use server-header filters instead.
4674 <term>Example usage:</term>
4677 <screen># Disarm the download link in Sourceforge's patch tracker
4679 +content-type-overwrite{text/plain}\
4680 +hide-content-disposition{block} }
4681 .sourceforge.net/tracker/download\.php</screen>
4689 <!-- ~~~~~ New section ~~~~~ -->
4690 <sect3 renderas="sect4" id="hide-if-modified-since">
4691 <title>hide-if-modified-since</title>
4697 <term>Typical use:</term>
4699 <para>Prevent yet another way to track the user's steps between sessions.</para>
4704 <term>Effect:</term>
4707 Deletes the <quote>If-Modified-Since:</quote> HTTP client header or modifies its value.
4714 <!-- Boolean, Parameterized, Multi-value -->
4716 <para>Parameterized.</para>
4721 <term>Parameter:</term>
4724 Keyword: <quote>block</quote>, or a user defined value that specifies a range of hours.
4733 Removing this header is useful for filter testing, where you want to force a real
4734 reload instead of getting status code <quote>304</quote>, which would cause the
4735 browser to use a cached copy of the page.
4738 Instead of removing the header, <literal>hide-if-modified-since</literal> can
4739 also add or subtract a random amount of time to/from the header's value.
4740 You specify a range of minutes where the random factor should be chosen from and
4741 <application>Privoxy</application> does the rest. A negative value means
4742 subtracting, a positive value adding.
4745 Randomizing the value of the <quote>If-Modified-Since:</quote> makes
4746 it less likely that the server can use the time as a cookie replacement,
4747 but you will run into caching problems if the random range is too high.
4750 It is a good idea to only use a small negative value and let
4751 <literal><link linkend="overwrite-last-modified">overwrite-last-modified</link></literal>
4752 handle the greater changes.
4755 It is also recommended to use this action together with
4756 <literal><link linkend="crunch-if-none-match">crunch-if-none-match</link></literal>,
4757 otherwise it's more or less pointless.
4763 <term>Example usage (section):</term>
4766 <screen># Let the browser revalidate but make tracking based on the time less likely.
4767 {+hide-if-modified-since{-60} \
4768 +overwrite-last-modified{randomize} \
4769 +crunch-if-none-match}
4778 <!-- ~~~~~ New section ~~~~~ -->
4779 <sect3 renderas="sect4" id="hide-from-header">
4780 <title>hide-from-header</title>
4784 <term>Typical use:</term>
4786 <para>Keep your (old and ill) browser from telling web servers your email address</para>
4791 <term>Effect:</term>
4794 Deletes any existing <quote>From:</quote> HTTP header, or replaces it with the
4802 <!-- Boolean, Parameterized, Multi-value -->
4804 <para>Parameterized.</para>
4809 <term>Parameter:</term>
4812 Keyword: <quote>block</quote>, or any user defined value.
4821 The keyword <quote>block</quote> will completely remove the header
4822 (not to be confused with the <literal><link linkend="block">block</link></literal>
4826 Alternately, you can specify any value you prefer to be sent to the web
4827 server. If you do, it is a matter of fairness not to use any address that
4828 is actually used by a real person.
4831 This action is rarely needed, as modern web browsers don't send
4832 <quote>From:</quote> headers anymore.
4838 <term>Example usage:</term>
4841 <screen>+hide-from-header{block}</screen> or
4842 <screen>+hide-from-header{spam-me-senseless@sittingduck.example.com}</screen>
4850 <!-- ~~~~~ New section ~~~~~ -->
4851 <sect3 renderas="sect4" id="hide-referrer">
4852 <title>hide-referrer</title>
4853 <anchor id="hide-referer">
4856 <term>Typical use:</term>
4858 <para>Conceal which link you followed to get to a particular site</para>
4863 <term>Effect:</term>
4866 Deletes the <quote>Referer:</quote> (sic) HTTP header from the client request,
4867 or replaces it with a forged one.
4874 <!-- Boolean, Parameterized, Multi-value -->
4876 <para>Parameterized.</para>
4881 <term>Parameter:</term>
4885 <para><quote>conditional-block</quote> to delete the header completely if the host has changed.</para>
4888 <para><quote>conditional-forge</quote> to forge the header if the host has changed.</para>
4891 <para><quote>block</quote> to delete the header unconditionally.</para>
4894 <para><quote>forge</quote> to pretend to be coming from the homepage of the server we are talking to.</para>
4897 <para>Any other string to set a user defined referrer.</para>
4907 <literal>conditional-block</literal> is the only parameter,
4908 that isn't easily detected in the server's log file. If it blocks the
4909 referrer, the request will look like the visitor used a bookmark or
4910 typed in the address directly.
4913 Leaving the referrer unmodified for requests on the same host
4914 allows the server owner to see the visitor's <quote>click path</quote>,
4915 but in most cases she could also get that information by comparing
4916 other parts of the log file: for example the User-Agent if it isn't
4917 a very common one, or the user's IP address if it doesn't change between
4921 Always blocking the referrer, or using a custom one, can lead to
4922 failures on servers that check the referrer before they answer any
4923 requests, in an attempt to prevent their content from being
4924 embedded or linked to elsewhere.
4927 Both <literal>conditional-block</literal> and <literal>forge</literal>
4928 will work with referrer checks, as long as content and valid referring page
4929 are on the same host. Most of the time that's the case.
4932 <literal>hide-referer</literal> is an alternate spelling of
4933 <literal>hide-referrer</literal> and the two can be can be freely
4934 substituted with each other. (<quote>referrer</quote> is the
4935 correct English spelling, however the HTTP specification has a bug - it
4936 requires it to be spelled as <quote>referer</quote>.)
4942 <term>Example usage:</term>
4945 <screen>+hide-referrer{forge}</screen> or
4946 <screen>+hide-referrer{http://www.yahoo.com/}</screen>
4954 <!-- ~~~~~ New section ~~~~~ -->
4955 <sect3 renderas="sect4" id="hide-user-agent">
4956 <title>hide-user-agent</title>
4960 <term>Typical use:</term>
4962 <para>Try to conceal your type of browser and client operating system</para>
4967 <term>Effect:</term>
4970 Replaces the value of the <quote>User-Agent:</quote> HTTP header
4971 in client requests with the specified value.
4978 <!-- Boolean, Parameterized, Multi-value -->
4980 <para>Parameterized.</para>
4985 <term>Parameter:</term>
4988 Any user-defined string.
4998 This can lead to problems on web sites that depend on looking at this header in
4999 order to customize their content for different browsers (which, by the
5000 way, is <emphasis>NOT</emphasis> the right thing to do: good web sites
5001 work browser-independently).
5005 Using this action in multi-user setups or wherever different types of
5006 browsers will access the same <application>Privoxy</application> is
5007 <emphasis>not recommended</emphasis>. In single-user, single-browser
5008 setups, you might use it to delete your OS version information from
5009 the headers, because it is an invitation to exploit known bugs for your
5010 OS. It is also occasionally useful to forge this in order to access
5011 sites that won't let you in otherwise (though there may be a good
5012 reason in some cases).
5015 More information on known user-agent strings can be found at
5016 <ulink url="http://www.user-agents.org/">http://www.user-agents.org/</ulink>
5018 <ulink url="http://en.wikipedia.org/wiki/User_agent">http://en.wikipedia.org/wiki/User_agent</ulink>.
5024 <term>Example usage:</term>
5027 <screen>+hide-user-agent{Netscape 6.1 (X11; I; Linux 2.4.18 i686)}</screen>
5035 <!-- ~~~~~ New section ~~~~~ -->
5036 <sect3 renderas="sect4" id="limit-connect">
5037 <title>limit-connect</title>
5041 <term>Typical use:</term>
5043 <para>Prevent abuse of <application>Privoxy</application> as a TCP proxy relay or disable SSL for untrusted sites</para>
5048 <term>Effect:</term>
5051 Specifies to which ports HTTP CONNECT requests are allowable.
5058 <!-- Boolean, Parameterized, Multi-value -->
5060 <para>Parameterized.</para>
5065 <term>Parameter:</term>
5068 A comma-separated list of ports or port ranges (the latter using dashes, with the minimum
5069 defaulting to 0 and the maximum to 65K).
5078 By default, i.e. if no <literal>limit-connect</literal> action applies,
5079 <application>Privoxy</application> allows HTTP CONNECT requests to all
5080 ports. Use <literal>limit-connect</literal> if fine-grained control
5081 is desired for some or all destinations.
5084 The CONNECT methods exists in HTTP to allow access to secure websites
5085 (<quote>https://</quote> URLs) through proxies. It works very simply:
5086 the proxy connects to the server on the specified port, and then
5087 short-circuits its connections to the client and to the remote server.
5088 This means CONNECT-enabled proxies can be used as TCP relays very easily.
5091 <application>Privoxy</application> relays HTTPS traffic without seeing
5092 the decoded content. Websites can leverage this limitation to circumvent &my-app;'s
5093 filters. By specifying an invalid port range you can disable HTTPS entirely.
5099 <term>Example usages:</term>
5101 <!-- I had trouble getting the spacing to look right in my browser -->
5102 <!-- I probably have the wrong font setup, bollocks. -->
5103 <!-- Apparently the emphasis tag uses a proportional font no matter what -->
5105 <screen>+limit-connect{443} # Port 443 is OK.
5106 +limit-connect{80,443} # Ports 80 and 443 are OK.
5107 +limit-connect{-3, 7, 20-100, 500-} # Ports less than 3, 7, 20 to 100 and above 500 are OK.
5108 +limit-connect{-} # All ports are OK
5109 +limit-connect{,} # No HTTPS/SSL traffic is allowed</screen>
5117 <!-- ~~~~~ New section ~~~~~ -->
5118 <sect3 renderas="sect4" id="limit-cookie-lifetime">
5119 <title>limit-cookie-lifetime</title>
5123 <term>Typical use:</term>
5125 <para>Limit the lifetime of HTTP cookies to a couple of minutes or hours.</para>
5130 <term>Effect:</term>
5133 Overwrites the expires field in Set-Cookie server headers if it's above the specified limit.
5140 <!-- Boolean, Parameterized, Multi-value -->
5142 <para>Parameterized.</para>
5147 <term>Parameter:</term>
5150 The lifetime limit in minutes, or 0.
5159 This action reduces the lifetime of HTTP cookies coming from the
5160 server to the specified number of minutes, starting from the time
5161 the cookie passes Privoxy.
5164 Cookies with a lifetime below the limit are not modified.
5165 The lifetime of session cookies is set to the specified limit.
5168 The effect of this action depends on the server.
5171 In case of servers which refresh their cookies with each response
5172 (or at least frequently), the lifetime limit set by this action
5174 Thus, a session associated with the cookie continues to work with
5175 this action enabled, as long as a new request is made before the
5176 last limit set is reached.
5179 However, some servers send their cookies once, with a lifetime of several
5180 years (the year 2037 is a popular choice), and do not refresh them
5181 until a certain event in the future, for example the user logging out.
5182 In this case this action may limit the absolute lifetime of the session,
5183 even if requests are made frequently.
5186 If the parameter is <quote>0</quote>, this action behaves like
5187 <literal><link linkend="session-cookies-only">session-cookies-only</link></literal>.
5193 <term>Example usages:</term>
5196 <screen>+limit-cookie-lifetime{60}
5204 <!-- ~~~~~ New section ~~~~~ -->
5205 <sect3 renderas="sect4" id="prevent-compression">
5206 <title>prevent-compression</title>
5210 <term>Typical use:</term>
5213 Ensure that servers send the content uncompressed, so it can be
5214 passed through <literal><link linkend="filter">filter</link></literal>s.
5220 <term>Effect:</term>
5223 Removes the Accept-Encoding header which can be used to ask for compressed transfer.
5230 <!-- Boolean, Parameterized, Multi-value -->
5232 <para>Boolean.</para>
5237 <term>Parameter:</term>
5249 More and more websites send their content compressed by default, which
5250 is generally a good idea and saves bandwidth. But the <literal><link
5251 linkend="filter">filter</link></literal> and
5252 <literal><link linkend="deanimate-gifs">deanimate-gifs</link></literal>
5253 actions need access to the uncompressed data.
5256 When compiled with zlib support (available since &my-app; 3.0.7), content that should be
5257 filtered is decompressed on-the-fly and you don't have to worry about this action.
5258 If you are using an older &my-app; version, or one that hasn't been compiled with zlib
5259 support, this action can be used to convince the server to send the content uncompressed.
5262 Most text-based instances compress very well, the size is seldom decreased by less than 50%,
5263 for markup-heavy instances like news feeds saving more than 90% of the original size isn't
5267 Not using compression will therefore slow down the transfer, and you should only
5268 enable this action if you really need it. As of &my-app; 3.0.7 it's disabled in all
5269 predefined action settings.
5272 Note that some (rare) ill-configured sites don't handle requests for uncompressed
5273 documents correctly. Broken PHP applications tend to send an empty document body,
5274 some IIS versions only send the beginning of the content. If you enable
5275 <literal>prevent-compression</literal> per default, you might want to add
5276 exceptions for those sites. See the example for how to do that.
5282 <term>Example usage (sections):</term>
5286 # Selectively turn off compression, and enable a filter
5288 { +filter{tiny-textforms} +prevent-compression }
5289 # Match only these sites
5294 # Or instead, we could set a universal default:
5296 { +prevent-compression }
5299 # Then maybe make exceptions for broken sites:
5301 { -prevent-compression }
5302 .compusa.com/</screen>
5311 <!-- ~~~~~ New section ~~~~~ -->
5312 <sect3 renderas="sect4" id="overwrite-last-modified">
5313 <title>overwrite-last-modified</title>
5319 <term>Typical use:</term>
5321 <para>Prevent yet another way to track the user's steps between sessions.</para>
5326 <term>Effect:</term>
5329 Deletes the <quote>Last-Modified:</quote> HTTP server header or modifies its value.
5336 <!-- Boolean, Parameterized, Multi-value -->
5338 <para>Parameterized.</para>
5343 <term>Parameter:</term>
5346 One of the keywords: <quote>block</quote>, <quote>reset-to-request-time</quote>
5347 and <quote>randomize</quote>
5356 Removing the <quote>Last-Modified:</quote> header is useful for filter
5357 testing, where you want to force a real reload instead of getting status
5358 code <quote>304</quote>, which would cause the browser to reuse the old
5359 version of the page.
5362 The <quote>randomize</quote> option overwrites the value of the
5363 <quote>Last-Modified:</quote> header with a randomly chosen time
5364 between the original value and the current time. In theory the server
5365 could send each document with a different <quote>Last-Modified:</quote>
5366 header to track visits without using cookies. <quote>Randomize</quote>
5367 makes it impossible and the browser can still revalidate cached documents.
5370 <quote>reset-to-request-time</quote> overwrites the value of the
5371 <quote>Last-Modified:</quote> header with the current time. You could use
5372 this option together with
5373 <literal><link linkend="hide-if-modified-since">hide-if-modified-since</link></literal>
5374 to further customize your random range.
5377 The preferred parameter here is <quote>randomize</quote>. It is safe
5378 to use, as long as the time settings are more or less correct.
5379 If the server sets the <quote>Last-Modified:</quote> header to the time
5380 of the request, the random range becomes zero and the value stays the same.
5381 Therefore you should later randomize it a second time with
5382 <literal><link linkend="hide-if-modified-since">hided-if-modified-since</link></literal>,
5386 It is also recommended to use this action together with
5387 <literal><link linkend="crunch-if-none-match">crunch-if-none-match</link></literal>.
5393 <term>Example usage:</term>
5396 <screen># Let the browser revalidate without being tracked across sessions
5397 { +hide-if-modified-since{-60} \
5398 +overwrite-last-modified{randomize} \
5399 +crunch-if-none-match}
5408 <!-- ~~~~~ New section ~~~~~ -->
5409 <sect3 renderas="sect4" id="redirect">
5410 <title>redirect</title>
5416 <term>Typical use:</term>
5419 Redirect requests to other sites.
5425 <term>Effect:</term>
5428 Convinces the browser that the requested document has been moved
5429 to another location and the browser should get it from there.
5436 <!-- Boolean, Parameterized, Multi-value -->
5438 <para>Parameterized</para>
5443 <term>Parameter:</term>
5446 An absolute URL or a single pcrs command.
5455 Requests to which this action applies are answered with a
5456 HTTP redirect to URLs of your choosing. The new URL is
5457 either provided as parameter, or derived by applying a
5458 single pcrs command to the original URL.
5461 The syntax for pcrs commands is documented in the
5462 <link linkend="filter-file">filter file</link> section.
5465 Requests can't be blocked and redirected at the same time,
5466 applying this action together with
5467 <literal><link linkend="block">block</link></literal>
5468 is a configuration error. Currently the request is blocked
5469 and an error message logged, the behavior may change in the
5470 future and result in Privoxy rejecting the action file.
5473 This action can be combined with
5474 <literal><link linkend="fast-redirects">fast-redirects{check-decoded-url}</link></literal>
5475 to redirect to a decoded version of a rewritten URL.
5478 Use this action carefully, make sure not to create redirection loops
5479 and be aware that using your own redirects might make it
5480 possible to fingerprint your requests.
5483 In case of problems with your redirects, or simply to watch
5484 them working, enable <link linkend="DEBUG">debug 128</link>.
5490 <term>Example usages:</term>
5493 <screen># Replace example.com's style sheet with another one
5494 { +redirect{http://localhost/css-replacements/example.com.css} }
5495 example.com/stylesheet\.css
5497 # Create a short, easy to remember nickname for a favorite site
5498 # (relies on the browser to accept and forward invalid URLs to &my-app;)
5499 { +redirect{https://www.privoxy.org/user-manual/actions-file.html} }
5502 # Always use the expanded view for Undeadly.org articles
5503 # (Note the $ at the end of the URL pattern to make sure
5504 # the request for the rewritten URL isn't redirected as well)
5505 {+redirect{s@$@&mode=expanded@}}
5506 undeadly.org/cgi\?action=article&sid=\d*$
5508 # Redirect Google search requests to MSN
5509 {+redirect{s@^http://[^/]*/search\?q=([^&]*).*@http://search.msn.com/results.aspx?q=$1@}}
5512 # Redirect MSN search requests to Yahoo
5513 {+redirect{s@^http://[^/]*/results\.aspx\?q=([^&]*).*@http://search.yahoo.com/search?p=$1@}}
5514 search.msn.com//results\.aspx\?q=
5516 # Redirect http://example.com/&bla=fasel&toChange=foo (and any other value but "bar")
5517 # to http://example.com/&bla=fasel&toChange=bar
5519 # The URL pattern makes sure that the following request isn't redirected again.
5520 {+redirect{s@toChange=[^&]+@toChange=bar@}}
5521 example.com/.*toChange=(?!bar)
5523 # Add a shortcut to look up illumos bugs
5524 {+redirect{s@^http://i([0-9]+)/.*@https://www.illumos.org/issues/$1@}}
5525 # Redirected URL = http://i4974/
5526 # Redirect Destination = https://www.illumos.org/issues/4974
5527 i[0-9][0-9][0-9][0-9]*/
5529 # Redirect remote requests for this manual
5530 # to the local version delivered by Privoxy
5531 {+redirect{s@^http://www@http://config@}}
5532 www.privoxy.org/user-manual/</screen>
5541 <!-- ~~~~~ New section ~~~~~ -->
5542 <sect3 renderas="sect4" id="server-header-filter">
5543 <title>server-header-filter</title>
5547 <term>Typical use:</term>
5550 Rewrite or remove single server headers.
5556 <term>Effect:</term>
5559 All server headers to which this action applies are filtered on-the-fly
5560 through the specified regular expression based substitutions.
5567 <!-- boolean, parameterized, Multi-value -->
5569 <para>Multi-value.</para>
5574 <term>Parameter:</term>
5577 The name of a server-header filter, as defined in one of the
5578 <link linkend="filter-file">filter files</link>.
5587 Server-header filters are applied to each header on its own, not to
5588 all at once. This makes it easier to diagnose problems, but on the downside
5589 you can't write filters that only change header x if header y's value is z.
5590 You can do that by using tags though.
5593 Server-header filters are executed after the other header actions have finished
5594 and use their output as input.
5597 Please refer to the <link linkend="filter-file">filter file chapter</link>
5598 to learn which server-header filters are available by default, and how to
5605 <term>Example usage (section):</term>
5609 {+server-header-filter{html-to-xml}}
5610 example.org/xml-instance-that-is-delivered-as-html
5612 {+server-header-filter{xml-to-html}}
5613 example.org/instance-that-is-delivered-as-xml-but-is-not
5623 <!-- ~~~~~ New section ~~~~~ -->
5624 <sect3 renderas="sect4" id="server-header-tagger">
5625 <title>server-header-tagger</title>
5629 <term>Typical use:</term>
5632 Enable or disable filters based on the Content-Type header.
5638 <term>Effect:</term>
5641 Server headers to which this action applies are filtered on-the-fly through
5642 the specified regular expression based substitutions, the result is used as
5650 <!-- boolean, parameterized, Multi-value -->
5652 <para>Multi-value.</para>
5657 <term>Parameter:</term>
5660 The name of a server-header tagger, as defined in one of the
5661 <link linkend="filter-file">filter files</link>.
5670 Server-header taggers are applied to each header on its own,
5671 and as the header isn't modified, each tagger <quote>sees</quote>
5675 Server-header taggers are executed before all other header actions
5676 that modify server headers. Their tags can be used to control
5677 all of the other server-header actions, the content filters
5678 and the crunch actions (<link linkend="redirect">redirect</link>
5679 and <link linkend="block">block</link>).
5682 Obviously crunching based on tags created by server-header taggers
5683 doesn't prevent the request from showing up in the server's log file.
5690 <term>Example usage (section):</term>
5694 # Tag every request with the content type declared by the server
5695 {+server-header-tagger{content-type}}
5698 # If the response has a tag starting with 'image/' enable an external
5699 # filter that only applies to images.
5701 # Note that the filter is not available by default, it's just a
5702 # <literal><link linkend="external-filter-syntax">silly example</link></literal>.
5703 {+external-filter{rotate-image} +force-text-mode}
5714 <!-- ~~~~~ New section ~~~~~ -->
5715 <sect3 renderas="sect4" id="session-cookies-only">
5716 <title>session-cookies-only</title>
5720 <term>Typical use:</term>
5723 Allow only temporary <quote>session</quote> cookies (for the current
5724 browser session <emphasis>only</emphasis>).
5730 <term>Effect:</term>
5733 Deletes the <quote>expires</quote> field from <quote>Set-Cookie:</quote>
5734 server headers. Most browsers will not store such cookies permanently and
5735 forget them in between sessions.
5742 <!-- Boolean, Parameterized, Multi-value -->
5744 <para>Boolean.</para>
5749 <term>Parameter:</term>
5761 This is less strict than <literal><link linkend="crunch-incoming-cookies">crunch-incoming-cookies</link></literal> /
5762 <literal><link linkend="crunch-outgoing-cookies">crunch-outgoing-cookies</link></literal> and allows you to browse
5763 websites that insist or rely on setting cookies, without compromising your privacy too badly.
5766 Most browsers will not permanently store cookies that have been processed by
5767 <literal>session-cookies-only</literal> and will forget about them between sessions.
5768 This makes profiling cookies useless, but won't break sites which require cookies so
5769 that you can log in for transactions. This is generally turned on for all
5770 sites, and is the recommended setting.
5773 It makes <emphasis>no sense at all</emphasis> to use <literal>session-cookies-only</literal>
5774 together with <literal><link linkend="crunch-incoming-cookies">crunch-incoming-cookies</link></literal> or
5775 <literal><link linkend="crunch-outgoing-cookies">crunch-outgoing-cookies</link></literal>. If you do, cookies
5776 will be plainly killed.
5779 Note that it is up to the browser how it handles such cookies without an <quote>expires</quote>
5780 field. If you use an exotic browser, you might want to try it out to be sure.
5783 This setting also has no effect on cookies that may have been stored
5784 previously by the browser before starting <application>Privoxy</application>.
5785 These would have to be removed manually.
5788 <application>Privoxy</application> also uses
5789 the <link linkend="filter-content-cookies">content-cookies filter</link>
5790 to block some types of cookies. Content cookies are not effected by
5791 <literal>session-cookies-only</literal>.
5797 <term>Example usage:</term>
5800 <screen>+session-cookies-only</screen>
5808 <!-- ~~~~~ New section ~~~~~ -->
5809 <sect3 renderas="sect4" id="set-image-blocker">
5810 <title>set-image-blocker</title>
5814 <term>Typical use:</term>
5816 <para>Choose the replacement for blocked images</para>
5821 <term>Effect:</term>
5824 This action alone doesn't do anything noticeable. If <emphasis>both</emphasis>
5825 <literal><link linkend="block">block</link></literal> <emphasis>and</emphasis> <literal><link
5826 linkend="handle-as-image">handle-as-image</link></literal> <emphasis>also</emphasis>
5827 apply, i.e. if the request is to be blocked as an image,
5828 <emphasis>then</emphasis> the parameter of this action decides what will be
5829 sent as a replacement.
5836 <!-- Boolean, Parameterized, Multi-value -->
5838 <para>Parameterized.</para>
5843 <term>Parameter:</term>
5848 <quote>pattern</quote> to send a built-in checkerboard pattern image. The image is visually
5849 decent, scales very well, and makes it obvious where banners were busted.
5854 <quote>blank</quote> to send a built-in transparent image. This makes banners disappear
5855 completely, but makes it hard to detect where <application>Privoxy</application> has blocked
5856 images on a given page and complicates troubleshooting if <application>Privoxy</application>
5857 has blocked innocent images, like navigation icons.
5862 <quote><replaceable class="parameter">target-url</replaceable></quote> to
5863 send a redirect to <replaceable class="parameter">target-url</replaceable>. You can redirect
5864 to any image anywhere, even in your local filesystem via <quote>file:///</quote> URL.
5865 (But note that not all browsers support redirecting to a local file system).
5868 A good application of redirects is to use special <application>Privoxy</application>-built-in
5869 URLs, which send the built-in images, as <replaceable class="parameter">target-url</replaceable>.
5870 This has the same visual effect as specifying <quote>blank</quote> or <quote>pattern</quote> in
5871 the first place, but enables your browser to cache the replacement image, instead of requesting
5872 it over and over again.
5883 The URLs for the built-in images are <quote>http://config.privoxy.org/send-banner?type=<replaceable
5884 class="parameter">type</replaceable></quote>, where <replaceable class="parameter">type</replaceable> is
5885 either <quote>blank</quote> or <quote>pattern</quote>.
5888 There is a third (advanced) type, called <quote>auto</quote>. It is <emphasis>NOT</emphasis> to be
5889 used in <literal>set-image-blocker</literal>, but meant for use from <link linkend="filter-file">filters</link>.
5890 Auto will select the type of image that would have applied to the referring page, had it been an image.
5896 <term>Example usage:</term>
5902 <screen>+set-image-blocker{pattern}</screen>
5905 Redirect to the BSD daemon:
5908 <screen>+set-image-blocker{http://www.freebsd.org/gifs/dae_up3.gif}</screen>
5911 Redirect to the built-in pattern for better caching:
5914 <screen>+set-image-blocker{http://config.privoxy.org/send-banner?type=pattern}</screen>
5922 <!-- ~~~~~ New section ~~~~~ -->
5923 <sect3 id="summary">
5924 <title>Summary</title>
5926 Note that many of these actions have the potential to cause a page to
5927 misbehave, possibly even not to display at all. There are many ways
5928 a site designer may choose to design his site, and what HTTP header
5929 content, and other criteria, he may depend on. There is no way to have hard
5930 and fast rules for all sites. See the <link
5931 linkend="ACTIONSANAT">Appendix</link> for a brief example on troubleshooting
5937 <!-- ~~~~~ New section ~~~~~ -->
5938 <sect2 id="aliases">
5939 <title>Aliases</title>
5941 Custom <quote>actions</quote>, known to <application>Privoxy</application>
5942 as <quote>aliases</quote>, can be defined by combining other actions.
5943 These can in turn be invoked just like the built-in actions.
5944 Currently, an alias name can contain any character except space, tab,
5946 <quote>{</quote> and <quote>}</quote>, but we <emphasis>strongly
5947 recommend</emphasis> that you only use <quote>a</quote> to <quote>z</quote>,
5948 <quote>0</quote> to <quote>9</quote>, <quote>+</quote>, and <quote>-</quote>.
5949 Alias names are not case sensitive, and are not required to start with a
5950 <quote>+</quote> or <quote>-</quote> sign, since they are merely textually
5954 Aliases can be used throughout the actions file, but they <emphasis>must be
5955 defined in a special section at the top of the file!</emphasis>
5956 And there can only be one such section per actions file. Each actions file may
5957 have its own alias section, and the aliases defined in it are only visible
5961 There are two main reasons to use aliases: One is to save typing for frequently
5962 used combinations of actions, the other one is a gain in flexibility: If you
5963 decide once how you want to handle shops by defining an alias called
5964 <quote>shop</quote>, you can later change your policy on shops in
5965 <emphasis>one</emphasis> place, and your changes will take effect everywhere
5966 in the actions file where the <quote>shop</quote> alias is used. Calling aliases
5967 by their purpose also makes your actions files more readable.
5970 Currently, there is one big drawback to using aliases, though:
5971 <application>Privoxy</application>'s built-in web-based action file
5972 editor honors aliases when reading the actions files, but it expands
5973 them before writing. So the effects of your aliases are of course preserved,
5974 but the aliases themselves are lost when you edit sections that use aliases
5979 Now let's define some aliases...
5984 # Useful custom aliases we can use later.
5986 # Note the (required!) section header line and that this section
5987 # must be at the top of the actions file!
5991 # These aliases just save typing later:
5992 # (Note that some already use other aliases!)
5994 +crunch-all-cookies = +<link linkend="CRUNCH-INCOMING-COOKIES">crunch-incoming-cookies</link> +<link linkend="CRUNCH-OUTGOING-COOKIES">crunch-outgoing-cookies</link>
5995 -crunch-all-cookies = -<link linkend="CRUNCH-INCOMING-COOKIES">crunch-incoming-cookies</link> -<link linkend="CRUNCH-OUTGOING-COOKIES">crunch-outgoing-cookies</link>
5996 +block-as-image = +block{Blocked image.} +handle-as-image
5997 allow-all-cookies = -crunch-all-cookies -<link linkend="SESSION-COOKIES-ONLY">session-cookies-only</link> -<link linkend="FILTER-CONTENT-COOKIES">filter{content-cookies}</link>
5999 # These aliases define combinations of actions
6000 # that are useful for certain types of sites:
6002 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>
6004 shop = -crunch-all-cookies -<link linkend="FILTER-ALL-POPUPS">filter{all-popups}</link>
6006 # Short names for other aliases, for really lazy people ;-)
6008 c0 = +crunch-all-cookies
6009 c1 = -crunch-all-cookies</screen>
6013 ...and put them to use. These sections would appear in the lower part of an
6014 actions file and define exceptions to the default actions (as specified further
6015 up for the <quote>/</quote> pattern):
6020 # These sites are either very complex or very keen on
6021 # user data and require minimal interference to work:
6024 .office.microsoft.com
6025 .windowsupdate.microsoft.com
6026 # Gmail is really mail.google.com, not gmail.com
6030 # Allow cookies (for setting and retrieving your customer data)
6034 .worldpay.com # for quietpc.com
6037 # These shops require pop-ups:
6039 {-filter{all-popups} -filter{unsolicited-popups}}
6041 .overclockers.co.uk</screen>
6045 Aliases like <quote>shop</quote> and <quote>fragile</quote> are typically used for
6046 <quote>problem</quote> sites that require more than one action to be disabled
6047 in order to function properly.
6053 <!-- ~~~~~ New section ~~~~~ -->
6054 <sect2 id="act-examples">
6055 <title>Actions Files Tutorial</title>
6057 The above chapters have shown <link linkend="actions-file">which actions files
6058 there are and how they are organized</link>, how actions are <link
6059 linkend="actions">specified</link> and <link linkend="actions-apply">applied
6060 to URLs</link>, how <link linkend="af-patterns">patterns</link> work, and how to
6061 define and use <link linkend="aliases">aliases</link>. Now, let's look at an
6062 example <filename>match-all.action</filename>, <filename>default.action</filename>
6063 and <filename>user.action</filename> file and see how all these pieces come together:
6066 <sect3 id="match-all">
6067 <title>match-all.action</title>
6069 Remember <emphasis>all actions are disabled when matching starts</emphasis>,
6070 so we have to explicitly enable the ones we want.
6074 While the <filename>match-all.action</filename> file only contains a
6075 single section, it is probably the most important one. It has only one
6076 pattern, <quote><literal>/</literal></quote>, but this pattern
6077 <link linkend="af-patterns">matches all URLs</link>. Therefore, the set of
6078 actions used in this <quote>default</quote> section <emphasis>will
6079 be applied to all requests as a start</emphasis>. It can be partly or
6080 wholly overridden by other actions files like <filename>default.action</filename>
6081 and <filename>user.action</filename>, but it will still be largely responsible
6082 for your overall browsing experience.
6086 Again, at the start of matching, all actions are disabled, so there is
6087 no need to disable any actions here. (Remember: a <quote>+</quote>
6088 preceding the action name enables the action, a <quote>-</quote> disables!).
6089 Also note how this long line has been made more readable by splitting it into
6090 multiple lines with line continuation.
6096 +<link linkend="CHANGE-X-FORWARDED-FOR">change-x-forwarded-for{block}</link> \
6097 +<link linkend="HIDE-FROM-HEADER">hide-from-header{block}</link> \
6098 +<link linkend="SET-IMAGE-BLOCKER">set-image-blocker{pattern}</link> \
6105 The default behavior is now set.
6109 <sect3 id="default-action">
6110 <title>default.action</title>
6113 If you aren't a developer, there's no need for you to edit the
6114 <filename>default.action</filename> file. It is maintained by
6115 the &my-app; developers and if you disagree with some of the
6116 sections, you should overrule them in your <filename>user.action</filename>.
6120 Understanding the <filename>default.action</filename> file can
6121 help you with your <filename>user.action</filename>, though.
6125 The first section in this file is a special section for internal use
6126 that prevents older &my-app; versions from reading the file:
6131 ##########################################################################
6132 # Settings -- Don't change! For internal Privoxy use ONLY.
6133 ##########################################################################
6135 for-privoxy-version=3.0.11</screen>
6139 After that comes the (optional) alias section. We'll use the example
6140 section from the above <link linkend="aliases">chapter on aliases</link>,
6141 that also explains why and how aliases are used:
6146 ##########################################################################
6148 ##########################################################################
6151 # These aliases just save typing later:
6152 # (Note that some already use other aliases!)
6154 +crunch-all-cookies = +<link linkend="CRUNCH-INCOMING-COOKIES">crunch-incoming-cookies</link> +<link linkend="CRUNCH-OUTGOING-COOKIES">crunch-outgoing-cookies</link>
6155 -crunch-all-cookies = -<link linkend="CRUNCH-INCOMING-COOKIES">crunch-incoming-cookies</link> -<link linkend="CRUNCH-OUTGOING-COOKIES">crunch-outgoing-cookies</link>
6156 +block-as-image = +block{Blocked image.} +handle-as-image
6157 mercy-for-cookies = -crunch-all-cookies -<link linkend="SESSION-COOKIES-ONLY">session-cookies-only</link> -<link linkend="FILTER-CONTENT-COOKIES">filter{content-cookies}</link>
6159 # These aliases define combinations of actions
6160 # that are useful for certain types of sites:
6162 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>
6163 shop = -crunch-all-cookies -<link linkend="FILTER-ALL-POPUPS">filter{all-popups}</link></screen>
6167 The first of our specialized sections is concerned with <quote>fragile</quote>
6168 sites, i.e. sites that require minimum interference, because they are either
6169 very complex or very keen on tracking you (and have mechanisms in place that
6170 make them unusable for people who avoid being tracked). We will simply use
6171 our pre-defined <literal>fragile</literal> alias instead of stating the list
6172 of actions explicitly:
6177 ##########################################################################
6178 # Exceptions for sites that'll break under the default action set:
6179 ##########################################################################
6181 # "Fragile" Use a minimum set of actions for these sites (see alias above):
6184 .office.microsoft.com # surprise, surprise!
6185 .windowsupdate.microsoft.com
6186 mail.google.com</screen>
6190 Shopping sites are not as fragile, but they typically
6191 require cookies to log in, and pop-up windows for shopping
6192 carts or item details. Again, we'll use a pre-defined alias:
6201 .worldpay.com # for quietpc.com
6203 .scan.co.uk</screen>
6207 The <literal><link linkend="FAST-REDIRECTS">fast-redirects</link></literal>
6208 action, which may have been enabled in <filename>match-all.action</filename>,
6209 breaks some sites. So disable it for popular sites where we know it misbehaves:
6214 { -<link linkend="FAST-REDIRECTS">fast-redirects</link> }
6218 .altavista.com/.*(like|url|link):http
6219 .altavista.com/trans.*urltext=http
6220 .nytimes.com</screen>
6224 It is important that <application>Privoxy</application> knows which
6225 URLs belong to images, so that <emphasis>if</emphasis> they are to
6226 be blocked, a substitute image can be sent, rather than an HTML page.
6227 Contacting the remote site to find out is not an option, since it
6228 would destroy the loading time advantage of banner blocking, and it
6229 would feed the advertisers information about you. We can mark any
6230 URL as an image with the <literal><link
6231 linkend="handle-as-image">handle-as-image</link></literal> action,
6232 and marking all URLs that end in a known image file extension is a
6238 ##########################################################################
6240 ##########################################################################
6242 # Define which file types will be treated as images, in case they get
6243 # blocked further down this file:
6245 { +<link linkend="HANDLE-AS-IMAGE">handle-as-image</link> }
6246 /.*\.(gif|jpe?g|png|bmp|ico)$</screen>
6250 And then there are known banner sources. They often use scripts to
6251 generate the banners, so it won't be visible from the URL that the
6252 request is for an image. Hence we block them <emphasis>and</emphasis>
6253 mark them as images in one go, with the help of our
6254 <literal>+block-as-image</literal> alias defined above. (We could of
6255 course just as well use <literal>+<link linkend="block">block</link>
6256 +<link linkend="handle-as-image">handle-as-image</link></literal> here.)
6257 Remember that the type of the replacement image is chosen by the
6258 <literal><link linkend="set-image-blocker">set-image-blocker</link></literal>
6259 action. Since all URLs have matched the default section with its
6260 <literal>+<link linkend="set-image-blocker">set-image-blocker</link>{pattern}</literal>
6261 action before, it still applies and needn't be repeated:
6266 # Known ad generators:
6271 .ad.*.doubleclick.net
6272 .a.yimg.com/(?:(?!/i/).)*$
6273 .a[0-9].yimg.com/(?:(?!/i/).)*$
6279 One of the most important jobs of <application>Privoxy</application>
6280 is to block banners. Many of these can be <quote>blocked</quote>
6281 by the <literal><link linkend="filter">filter</link>{banners-by-size}</literal>
6282 action, which we enabled above, and which deletes the references to banner
6283 images from the pages while they are loaded, so the browser doesn't request
6284 them anymore, and hence they don't need to be blocked here. But this naturally
6285 doesn't catch all banners, and some people choose not to use filters, so we
6286 need a comprehensive list of patterns for banner URLs here, and apply the
6287 <literal><link linkend="block">block</link></literal> action to them.
6290 First comes many generic patterns, which do most of the work, by
6291 matching typical domain and path name components of banners. Then comes
6292 a list of individual patterns for specific sites, which is omitted here
6293 to keep the example short:
6298 ##########################################################################
6299 # Block these fine banners:
6300 ##########################################################################
6301 { <link linkend="BLOCK">+block{Banner ads.}</link> }
6309 /.*count(er)?\.(pl|cgi|exe|dll|asp|php[34]?)
6310 /(?:.*/)?(publicite|werbung|rekla(ma|me|am)|annonse|maino(kset|nta|s)?)/
6312 # Site-specific patterns (abbreviated):
6314 .hitbox.com</screen>
6318 It's quite remarkable how many advertisers actually call their banner
6319 servers ads.<replaceable>company</replaceable>.com, or call the directory
6320 in which the banners are stored simply <quote>banners</quote>. So the above
6321 generic patterns are surprisingly effective.
6324 But being very generic, they necessarily also catch URLs that we don't want
6325 to block. The pattern <literal>.*ads.</literal> e.g. catches
6326 <quote>nasty-<emphasis>ads</emphasis>.nasty-corp.com</quote> as intended,
6327 but also <quote>downlo<emphasis>ads</emphasis>.sourcefroge.net</quote> or
6328 <quote><emphasis>ads</emphasis>l.some-provider.net.</quote> So here come some
6329 well-known exceptions to the <literal>+<link linkend="BLOCK">block</link></literal>
6333 Note that these are exceptions to exceptions from the default! Consider the URL
6334 <quote>downloads.sourcefroge.net</quote>: Initially, all actions are deactivated,
6335 so it wouldn't get blocked. Then comes the defaults section, which matches the
6336 URL, but just deactivates the <literal><link linkend="BLOCK">block</link></literal>
6337 action once again. Then it matches <literal>.*ads.</literal>, an exception to the
6338 general non-blocking policy, and suddenly
6339 <literal><link linkend="BLOCK">+block</link></literal> applies. And now, it'll match
6340 <literal>.*loads.</literal>, where <literal><link linkend="BLOCK">-block</link></literal>
6341 applies, so (unless it matches <emphasis>again</emphasis> further down) it ends up
6342 with no <literal><link linkend="BLOCK">block</link></literal> action applying.
6347 ##########################################################################
6348 # Save some innocent victims of the above generic block patterns:
6349 ##########################################################################
6353 { -<link linkend="BLOCK">block</link> }
6354 adv[io]*. # (for advogato.org and advice.*)
6355 adsl. # (has nothing to do with ads)
6356 adobe. # (has nothing to do with ads either)
6357 ad[ud]*. # (adult.* and add.*)
6358 .edu # (universities don't host banners (yet!))
6359 .*loads. # (downloads, uploads etc)
6367 www.globalintersec.com/adv # (adv = advanced)
6368 www.ugu.com/sui/ugu/adv</screen>
6372 Filtering source code can have nasty side effects,
6373 so make an exception for our friends at sourceforge.net,
6374 and all paths with <quote>cvs</quote> in them. Note that
6375 <literal>-<link linkend="FILTER">filter</link></literal>
6376 disables <emphasis>all</emphasis> filters in one fell swoop!
6381 # Don't filter code!
6383 { -<link linkend="FILTER">filter</link> }
6388 .sourceforge.net</screen>
6392 The actual <filename>default.action</filename> is of course much more
6393 comprehensive, but we hope this example made clear how it works.
6398 <sect3 id="user-action"><title>user.action</title>
6401 So far we are painting with a broad brush by setting general policies,
6402 which would be a reasonable starting point for many people. Now,
6403 you might want to be more specific and have customized rules that
6404 are more suitable to your personal habits and preferences. These would
6405 be for narrowly defined situations like your ISP or your bank, and should
6406 be placed in <filename>user.action</filename>, which is parsed after all other
6407 actions files and hence has the last word, over-riding any previously
6408 defined actions. <filename>user.action</filename> is also a
6409 <emphasis>safe</emphasis> place for your personal settings, since
6410 <filename>default.action</filename> is actively maintained by the
6411 <application>Privoxy</application> developers and you'll probably want
6412 to install updated versions from time to time.
6416 So let's look at a few examples of things that one might typically do in
6417 <filename>user.action</filename>:
6421 <!-- brief sample user.action here -->
6425 # My user.action file. <fred@example.com></screen>
6429 As <link linkend="aliases">aliases</link> are local to the actions
6430 file that they are defined in, you can't use the ones from
6431 <filename>default.action</filename>, unless you repeat them here:
6436 # Aliases are local to the file they are defined in.
6437 # (Re-)define aliases for this file:
6441 # These aliases just save typing later, and the alias names should
6442 # be self explanatory.
6444 +crunch-all-cookies = +crunch-incoming-cookies +crunch-outgoing-cookies
6445 -crunch-all-cookies = -crunch-incoming-cookies -crunch-outgoing-cookies
6446 allow-all-cookies = -crunch-all-cookies -session-cookies-only
6447 allow-popups = -filter{all-popups}
6448 +block-as-image = +block{Blocked as image.} +handle-as-image
6449 -block-as-image = -block
6451 # These aliases define combinations of actions that are useful for
6452 # certain types of sites:
6454 fragile = -block -crunch-all-cookies -filter -fast-redirects -hide-referrer
6455 shop = -crunch-all-cookies allow-popups
6457 # Allow ads for selected useful free sites:
6459 allow-ads = -block -filter{banners-by-size} -filter{banners-by-link}
6461 # Alias for specific file types that are text, but might have conflicting
6462 # MIME types. We want the browser to force these to be text documents.
6463 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>
6468 Say you have accounts on some sites that you visit regularly, and
6469 you don't want to have to log in manually each time. So you'd like
6470 to allow persistent cookies for these sites. The
6471 <literal>allow-all-cookies</literal> alias defined above does exactly
6472 that, i.e. it disables crunching of cookies in any direction, and the
6473 processing of cookies to make them only temporary.
6478 { allow-all-cookies }
6482 .redhat.com</screen>
6486 Your bank is allergic to some filter, but you don't know which, so you disable them all:
6491 { -<link linkend="FILTER">filter</link> }
6492 .your-home-banking-site.com</screen>
6496 Some file types you may not want to filter for various reasons:
6501 # Technical documentation is likely to contain strings that might
6502 # erroneously get altered by the JavaScript-oriented filters:
6507 # And this stupid host sends streaming video with a wrong MIME type,
6508 # so that Privoxy thinks it is getting HTML and starts filtering:
6510 stupid-server.example.com/</screen>
6514 Example of a simple <link linkend="BLOCK">block</link> action. Say you've
6515 seen an ad on your favourite page on example.com that you want to get rid of.
6516 You have right-clicked the image, selected <quote>copy image location</quote>
6517 and pasted the URL below while removing the leading http://, into a
6518 <literal>{ +block{} }</literal> section. Note that <literal>{ +handle-as-image
6519 }</literal> need not be specified, since all URLs ending in
6520 <literal>.gif</literal> will be tagged as images by the general rules as set
6521 in default.action anyway:
6526 { +<link linkend="BLOCK">block</link>{Nasty ads.} }
6527 www.example.com/nasty-ads/sponsor\.gif
6528 another.example.net/more/junk/here/</screen>
6532 The URLs of dynamically generated banners, especially from large banner
6533 farms, often don't use the well-known image file name extensions, which
6534 makes it impossible for <application>Privoxy</application> to guess
6535 the file type just by looking at the URL.
6536 You can use the <literal>+block-as-image</literal> alias defined above for
6538 Note that objects which match this rule but then turn out NOT to be an
6539 image are typically rendered as a <quote>broken image</quote> icon by the
6540 browser. Use cautiously.
6549 ar.atwola.com/</screen>
6553 Now you noticed that the default configuration breaks Forbes Magazine,
6554 but you were too lazy to find out which action is the culprit, and you
6555 were again too lazy to give <link linkend="contact">feedback</link>, so
6556 you just used the <literal>fragile</literal> alias on the site, and
6557 -- <emphasis>whoa!</emphasis> -- it worked. The <literal>fragile</literal>
6558 aliases disables those actions that are most likely to break a site. Also,
6559 good for testing purposes to see if it is <application>Privoxy</application>
6560 that is causing the problem or not. We later find other regular sites
6561 that misbehave, and add those to our personalized list of troublemakers:
6569 .mybank.com</screen>
6573 You like the <quote>fun</quote> text replacements in <filename>default.filter</filename>,
6574 but it is disabled in the distributed actions file.
6575 So you'd like to turn it on in your private,
6576 update-safe config, once and for all:
6581 { +<link linkend="filter-fun">filter{fun}</link> }
6582 / # For ALL sites!</screen>
6586 Note that the above is not really a good idea: There are exceptions
6587 to the filters in <filename>default.action</filename> for things that
6588 really shouldn't be filtered, like code on CVS->Web interfaces. Since
6589 <filename>user.action</filename> has the last word, these exceptions
6590 won't be valid for the <quote>fun</quote> filtering specified here.
6594 You might also worry about how your favourite free websites are
6595 funded, and find that they rely on displaying banner advertisements
6596 to survive. So you might want to specifically allow banners for those
6597 sites that you feel provide value to you:
6609 Note that <literal>allow-ads</literal> has been aliased to
6610 <literal>-<link linkend="block">block</link></literal>,
6611 <literal>-<link linkend="filter-banners-by-size">filter{banners-by-size}</link></literal>, and
6612 <literal>-<link linkend="filter-banners-by-link">filter{banners-by-link}</link></literal> above.
6616 Invoke another alias here to force an over-ride of the MIME type <literal>
6617 application/x-sh</literal> which typically would open a download type
6618 dialog. In my case, I want to look at the shell script, and then I can save
6619 it should I choose to.
6629 <filename>user.action</filename> is generally the best place to define
6630 exceptions and additions to the default policies of
6631 <filename>default.action</filename>. Some actions are safe to have their
6632 default policies set here though. So let's set a default policy to have a
6633 <quote>blank</quote> image as opposed to the checkerboard pattern for
6634 <emphasis>ALL</emphasis> sites. <quote>/</quote> of course matches all URL
6640 { +<link linkend="set-image-blocker">set-image-blocker{blank}</link> }
6641 / # ALL sites</screen>
6647 <!-- ~ End section ~ -->
6651 <!-- ~ End section ~ -->
6653 <!-- ~~~~~~~~ New section Header ~~~~~~~~~ -->
6655 <sect1 id="filter-file">
6656 <title>Filter Files</title>
6659 On-the-fly text substitutions need
6660 to be defined in a <quote>filter file</quote>. Once defined, they
6661 can then be invoked as an <quote>action</quote>.
6665 &my-app; supports three different pcrs-based filter actions:
6666 <literal><link linkend="filter">filter</link></literal> to
6667 rewrite the content that is send to the client,
6668 <literal><link linkend="client-header-filter">client-header-filter</link></literal>
6669 to rewrite headers that are send by the client, and
6670 <literal><link linkend="server-header-filter">server-header-filter</link></literal>
6671 to rewrite headers that are send by the server.
6675 &my-app; also supports two tagger actions:
6676 <literal><link linkend="client-header-tagger">client-header-tagger</link></literal>
6678 <literal><link linkend="server-header-tagger">server-header-tagger</link></literal>.
6679 Taggers and filters use the same syntax in the filter files, the difference
6680 is that taggers don't modify the text they are filtering, but use a rewritten
6681 version of the filtered text as tag. The tags can then be used to change the
6682 applying actions through sections with <link linkend="tag-pattern">tag-patterns</link>.
6686 Finally &my-app; supports the
6687 <literal><link linkend="external-filter">external-filter</link></literal> action
6688 to enable <literal><link linkend="external-filter-syntax">external filters</link></literal>
6689 written in proper programming languages.
6694 Multiple filter files can be defined through the <literal> <link
6695 linkend="filterfile">filterfile</link></literal> config directive. The filters
6696 as supplied by the developers are located in
6697 <filename>default.filter</filename>. It is recommended that any locally
6698 defined or modified filters go in a separately defined file such as
6699 <filename>user.filter</filename>.
6703 Common tasks for content filters are to eliminate common annoyances in
6704 HTML and JavaScript, such as pop-up windows,
6705 exit consoles, crippled windows without navigation tools, the
6706 infamous <BLINK> tag etc, to suppress images with certain
6707 width and height attributes (standard banner sizes or web-bugs),
6708 or just to have fun.
6712 Enabled content filters are applied to any content whose
6713 <quote>Content Type</quote> header is recognised as a sign
6714 of text-based content, with the exception of <literal>text/plain</literal>.
6715 Use the <link linkend="FORCE-TEXT-MODE">force-text-mode</link> action
6716 to also filter other content.
6720 Substitutions are made at the source level, so if you want to <quote>roll
6721 your own</quote> filters, you should first be familiar with HTML syntax,
6722 and, of course, regular expressions.
6726 Just like the <link linkend="actions-file">actions files</link>, the
6727 filter file is organized in sections, which are called <emphasis>filters</emphasis>
6728 here. Each filter consists of a heading line, that starts with one of the
6729 <emphasis>keywords</emphasis> <literal>FILTER:</literal>,
6730 <literal>CLIENT-HEADER-FILTER:</literal> or <literal>SERVER-HEADER-FILTER:</literal>
6731 followed by the filter's <emphasis>name</emphasis>, and a short (one line)
6732 <emphasis>description</emphasis> of what it does. Below that line
6733 come the <emphasis>jobs</emphasis>, i.e. lines that define the actual
6734 text substitutions. By convention, the name of a filter
6735 should describe what the filter <emphasis>eliminates</emphasis>. The
6736 comment is used in the <ulink url="http://config.privoxy.org/">web-based
6737 user interface</ulink>.
6741 Once a filter called <replaceable>name</replaceable> has been defined
6742 in the filter file, it can be invoked by using an action of the form
6743 +<literal><link linkend="filter">filter</link>{<replaceable>name</replaceable>}</literal>
6744 in any <link linkend="actions-file">actions file</link>.
6748 Filter definitions start with a header line that contains the filter
6749 type, the filter name and the filter description.
6750 A content filter header line for a filter called <quote>foo</quote> could look
6755 <screen>FILTER: foo Replace all "foo" with "bar"</screen>
6759 Below that line, and up to the next header line, come the jobs that
6760 define what text replacements the filter executes. They are specified
6761 in a syntax that imitates <ulink url="http://www.perl.org/">Perl</ulink>'s
6762 <literal>s///</literal> operator. If you are familiar with Perl, you
6763 will find this to be quite intuitive, and may want to look at the
6764 PCRS documentation for the subtle differences to Perl behaviour.
6768 Most notably, the non-standard option letter <literal>U</literal> is supported,
6769 which turns the default to ungreedy matching (add <literal>?</literal> to
6770 quantifiers to turn them greedy again).
6774 The non-standard option letter <literal>D</literal> (dynamic) allows
6775 to use the variables $host, $origin (the IP address the request came from),
6776 $path and $url. They will be replaced with the value they refer to before
6777 the filter is executed.
6781 Note that '$' is a bad choice for a delimiter in a dynamic filter as you
6782 might end up with unintended variables if you use a variable name
6783 directly after the delimiter. Variables will be resolved without
6784 escaping anything, therefore you also have to be careful not to chose
6785 delimiters that appear in the replacement text. For example '<' should
6786 be save, while '?' will sooner or later cause conflicts with $url.
6790 The non-standard option letter <literal>T</literal> (trivial) prevents
6791 parsing for backreferences in the substitute. Use it if you want to include
6792 text like '$&' in your substitute without quoting.
6797 <ulink url="http://en.wikipedia.org/wiki/Regular_expressions"><quote>Regular
6798 Expressions</quote></ulink>, you might want to take a look at
6799 the <link linkend="regex">Appendix on regular expressions</link>, and
6800 see the <ulink url="http://perldoc.perl.org/perlre.html">Perl
6802 <ulink url="http://perldoc.perl.org/perlop.html">the
6803 <literal>s///</literal> operator's syntax</ulink> and <ulink
6804 url="http://perldoc.perl.org/perlre.html">Perl-style regular
6805 expressions</ulink> in general.
6806 The below examples might also help to get you started.
6810 <!-- ~~~~~~~~ New section Header ~~~~~~~~~ -->
6812 <sect2 id="filter-file-tut"><title>Filter File Tutorial</title>
6814 Now, let's complete our <quote>foo</quote> content filter. We have already defined
6815 the heading, but the jobs are still missing. Since all it does is to replace
6816 <quote>foo</quote> with <quote>bar</quote>, there is only one (trivial) job
6821 <screen>s/foo/bar/</screen>
6825 But wait! Didn't the comment say that <emphasis>all</emphasis> occurrences
6826 of <quote>foo</quote> should be replaced? Our current job will only take
6827 care of the first <quote>foo</quote> on each page. For global substitution,
6828 we'll need to add the <literal>g</literal> option:
6832 <screen>s/foo/bar/g</screen>
6836 Our complete filter now looks like this:
6839 <screen>FILTER: foo Replace all "foo" with "bar"
6840 s/foo/bar/g</screen>
6844 Let's look at some real filters for more interesting examples. Here you see
6845 a filter that protects against some common annoyances that arise from JavaScript
6846 abuse. Let's look at its jobs one after the other:
6852 FILTER: js-annoyances Get rid of particularly annoying JavaScript abuse
6854 # Get rid of JavaScript referrer tracking. Test page: http://www.randomoddness.com/untitled.htm
6856 s|(<script.*)document\.referrer(.*</script>)|$1"Not Your Business!"$2|Usg</screen>
6860 Following the header line and a comment, you see the job. Note that it uses
6861 <literal>|</literal> as the delimiter instead of <literal>/</literal>, because
6862 the pattern contains a forward slash, which would otherwise have to be escaped
6863 by a backslash (<literal>\</literal>).
6867 Now, let's examine the pattern: it starts with the text <literal><script.*</literal>
6868 enclosed in parentheses. Since the dot matches any character, and <literal>*</literal>
6869 means: <quote>Match an arbitrary number of the element left of myself</quote>, this
6870 matches <quote><script</quote>, followed by <emphasis>any</emphasis> text, i.e.
6871 it matches the whole page, from the start of the first <script> tag.
6875 That's more than we want, but the pattern continues: <literal>document\.referrer</literal>
6876 matches only the exact string <quote>document.referrer</quote>. The dot needed to
6877 be <emphasis>escaped</emphasis>, i.e. preceded by a backslash, to take away its
6878 special meaning as a joker, and make it just a regular dot. So far, the meaning is:
6879 Match from the start of the first <script> tag in a the page, up to, and including,
6880 the text <quote>document.referrer</quote>, if <emphasis>both</emphasis> are present
6881 in the page (and appear in that order).
6885 But there's still more pattern to go. The next element, again enclosed in parentheses,
6886 is <literal>.*</script></literal>. You already know what <literal>.*</literal>
6887 means, so the whole pattern translates to: Match from the start of the first <script>
6888 tag in a page to the end of the last <script> tag, provided that the text
6889 <quote>document.referrer</quote> appears somewhere in between.
6893 This is still not the whole story, since we have ignored the options and the parentheses:
6894 The portions of the page matched by sub-patterns that are enclosed in parentheses, will be
6895 remembered and be available through the variables <literal>$1, $2, ...</literal> in
6896 the substitute. The <literal>U</literal> option switches to ungreedy matching, which means
6897 that the first <literal>.*</literal> in the pattern will only <quote>eat up</quote> all
6898 text in between <quote><script</quote> and the <emphasis>first</emphasis> occurrence
6899 of <quote>document.referrer</quote>, and that the second <literal>.*</literal> will
6900 only span the text up to the <emphasis>first</emphasis> <quote></script></quote>
6901 tag. Furthermore, the <literal>s</literal> option says that the match may span
6902 multiple lines in the page, and the <literal>g</literal> option again means that the
6903 substitution is global.
6907 So, to summarize, the pattern means: Match all scripts that contain the text
6908 <quote>document.referrer</quote>. Remember the parts of the script from
6909 (and including) the start tag up to (and excluding) the string
6910 <quote>document.referrer</quote> as <literal>$1</literal>, and the part following
6911 that string, up to and including the closing tag, as <literal>$2</literal>.
6915 Now the pattern is deciphered, but wasn't this about substituting things? So
6916 lets look at the substitute: <literal>$1"Not Your Business!"$2</literal> is
6917 easy to read: The text remembered as <literal>$1</literal>, followed by
6918 <literal>"Not Your Business!"</literal> (<emphasis>including</emphasis>
6919 the quotation marks!), followed by the text remembered as <literal>$2</literal>.
6920 This produces an exact copy of the original string, with the middle part
6921 (the <quote>document.referrer</quote>) replaced by <literal>"Not Your
6922 Business!"</literal>.
6926 The whole job now reads: Replace <quote>document.referrer</quote> by
6927 <literal>"Not Your Business!"</literal> wherever it appears inside a
6928 <script> tag. Note that this job won't break JavaScript syntax,
6929 since both the original and the replacement are syntactically valid
6930 string objects. The script just won't have access to the referrer
6931 information anymore.
6935 We'll show you two other jobs from the JavaScript taming department, but
6936 this time only point out the constructs of special interest:
6941 # The status bar is for displaying link targets, not pointless blahblah
6943 s/window\.status\s*=\s*(['"]).*?\1/dUmMy=1/ig</screen>
6947 <literal>\s</literal> stands for whitespace characters (space, tab, newline,
6948 carriage return, form feed), so that <literal>\s*</literal> means: <quote>zero
6949 or more whitespace</quote>. The <literal>?</literal> in <literal>.*?</literal>
6950 makes this matching of arbitrary text ungreedy. (Note that the <literal>U</literal>
6951 option is not set). The <literal>['"]</literal> construct means: <quote>a single
6952 <emphasis>or</emphasis> a double quote</quote>. Finally, <literal>\1</literal> is
6953 a back-reference to the first parenthesis just like <literal>$1</literal> above,
6954 with the difference that in the <emphasis>pattern</emphasis>, a backslash indicates
6955 a back-reference, whereas in the <emphasis>substitute</emphasis>, it's the dollar.
6959 So what does this job do? It replaces assignments of single- or double-quoted
6960 strings to the <quote>window.status</quote> object with a dummy assignment
6961 (using a variable name that is hopefully odd enough not to conflict with
6962 real variables in scripts). Thus, it catches many cases where e.g. pointless
6963 descriptions are displayed in the status bar instead of the link target when
6964 you move your mouse over links.
6969 # Kill OnUnload popups. Yummy. Test: http://www.zdnet.com/zdsubs/yahoo/tree/yfs.html
6971 s/(<body [^>]*)onunload(.*>)/$1never$2/iU</screen>
6976 <ulink url="http://www.w3.org/TR/2000/REC-DOM-Level-2-Events-20001113/events.html#Events-eventgroupings-htmlevents">OnUnload
6977 event binding</ulink> in the HTML DOM was a <emphasis>CRIME</emphasis>.
6978 When I close a browser window, I want it to close and die. Basta.
6979 This job replaces the <quote>onunload</quote> attribute in
6980 <quote><body></quote> tags with the dummy word <literal>never</literal>.
6981 Note that the <literal>i</literal> option makes the pattern matching
6982 case-insensitive. Also note that ungreedy matching alone doesn't always guarantee
6983 a minimal match: In the first parenthesis, we had to use <literal>[^>]*</literal>
6984 instead of <literal>.*</literal> to prevent the match from exceeding the
6985 <body> tag if it doesn't contain <quote>OnUnload</quote>, but the page's
6990 The last example is from the fun department:
6995 FILTER: fun Fun text replacements
6997 # Spice the daily news:
6999 s/microsoft(?!\.com)/MicroSuck/ig</screen>
7003 Note the <literal>(?!\.com)</literal> part (a so-called negative lookahead)
7004 in the job's pattern, which means: Don't match, if the string
7005 <quote>.com</quote> appears directly following <quote>microsoft</quote>
7006 in the page. This prevents links to microsoft.com from being trashed, while
7007 still replacing the word everywhere else.
7012 # Buzzword Bingo (example for extended regex syntax)
7014 s* industry[ -]leading \
7016 | customer[ -]focused \
7017 | market[ -]driven \
7018 | award[ -]winning # Comments are OK, too! \
7019 | high[ -]performance \
7020 | solutions[ -]based \
7024 *<font color="red"><b>BINGO!</b></font> \
7029 The <literal>x</literal> option in this job turns on extended syntax, and allows for
7030 e.g. the liberal use of (non-interpreted!) whitespace for nicer formatting.
7038 <!-- ~~~~~~~~ New section Header ~~~~~~~~~ -->
7040 <sect2 id="predefined-filters"><title>The Pre-defined Filters</title>
7044 Note each filter is also listed in the +filter action section above. Please
7045 keep these listings in sync.
7050 The distribution <filename>default.filter</filename> file contains a selection of
7051 pre-defined filters for your convenience:
7056 <term><emphasis>js-annoyances</emphasis></term>
7059 The purpose of this filter is to get rid of particularly annoying JavaScript abuse.
7064 replaces JavaScript references to the browser's referrer information
7065 with the string "Not Your Business!". This compliments the <literal><link
7066 linkend="hide-referrer">hide-referrer</link></literal> action on the content level.
7071 removes the bindings to the DOM's
7072 <ulink url="http://www.w3.org/TR/2000/REC-DOM-Level-2-Events-20001113/events.html#Events-eventgroupings-htmlevents">unload
7073 event</ulink> which we feel has no right to exist and is responsible for most <quote>exit consoles</quote>, i.e.
7074 nasty windows that pop up when you close another one.
7079 removes code that causes new windows to be opened with undesired properties, such as being
7080 full-screen, non-resizeable, without location, status or menu bar etc.
7086 Use with caution. This is an aggressive filter, and can break sites that
7087 rely heavily on JavaScript.
7093 <term><emphasis>js-events</emphasis></term>
7096 This is a very radical measure. It removes virtually all JavaScript event bindings, which
7097 means that scripts can not react to user actions such as mouse movements or clicks, window
7098 resizing etc, anymore. Use with caution!
7101 We <emphasis>strongly discourage</emphasis> using this filter as a default since it breaks
7102 many legitimate scripts. It is meant for use only on extra-nasty sites (should you really
7109 <term><emphasis>html-annoyances</emphasis></term>
7112 This filter will undo many common instances of HTML based abuse.
7115 The <literal>BLINK</literal> and <literal>MARQUEE</literal> tags
7116 are neutralized (yeah baby!), and browser windows will be created as
7117 resizeable (as of course they should be!), and will have location,
7118 scroll and menu bars -- even if specified otherwise.
7124 <term><emphasis>content-cookies</emphasis></term>
7127 Most cookies are set in the HTTP dialog, where they can be intercepted
7129 <literal><link linkend="crunch-incoming-cookies">crunch-incoming-cookies</link></literal>
7130 and <literal><link linkend="crunch-outgoing-cookies">crunch-outgoing-cookies</link></literal>
7131 actions. But web sites increasingly make use of HTML meta tags and JavaScript
7132 to sneak cookies to the browser on the content level.
7135 This filter disables most HTML and JavaScript code that reads or sets
7136 cookies. It cannot detect all clever uses of these types of code, so it
7137 should not be relied on as an absolute fix. Use it wherever you would also
7138 use the cookie crunch actions.
7144 <term><emphasis>refresh-tags</emphasis></term>
7147 Disable any refresh tags if the interval is greater than nine seconds (so
7148 that redirections done via refresh tags are not destroyed). This is useful
7149 for dial-on-demand setups, or for those who find this HTML feature
7156 <term><emphasis>unsolicited-popups</emphasis></term>
7159 This filter attempts to prevent only <quote>unsolicited</quote> pop-up
7160 windows from opening, yet still allow pop-up windows that the user
7161 has explicitly chosen to open. It was added in version 3.0.1,
7162 as an improvement over earlier such filters.
7165 Technical note: The filter works by redefining the window.open JavaScript
7166 function to a dummy function, <literal>PrivoxyWindowOpen()</literal>,
7167 during the loading and rendering phase of each HTML page access, and
7168 restoring the function afterward.
7171 This is recommended only for browsers that cannot perform this function
7172 reliably themselves. And be aware that some sites require such windows
7173 in order to function normally. Use with caution.
7179 <term><emphasis>all-popups</emphasis></term>
7182 Attempt to prevent <emphasis>all</emphasis> pop-up windows from opening.
7183 Note this should be used with even more discretion than the above, since
7184 it is more likely to break some sites that require pop-ups for normal
7185 usage. Use with caution.
7191 <term><emphasis>img-reorder</emphasis></term>
7194 This is a helper filter that has no value if used alone. It makes the
7195 <literal>banners-by-size</literal> and <literal>banners-by-link</literal>
7196 (see below) filters more effective and should be enabled together with them.
7202 <term><emphasis>banners-by-size</emphasis></term>
7205 This filter removes image tags purely based on what size they are. Fortunately
7206 for us, many ads and banner images tend to conform to certain standardized
7207 sizes, which makes this filter quite effective for ad stripping purposes.
7210 Occasionally this filter will cause false positives on images that are not ads,
7211 but just happen to be of one of the standard banner sizes.
7214 Recommended only for those who require extreme ad blocking. The default
7215 block rules should catch 95+% of all ads <emphasis>without</emphasis> this filter enabled.
7221 <term><emphasis>banners-by-link</emphasis></term>
7224 This is an experimental filter that attempts to kill any banners if
7225 their URLs seem to point to known or suspected click trackers. It is currently
7226 not of much value and is not recommended for use by default.
7232 <term><emphasis>webbugs</emphasis></term>
7235 Webbugs are small, invisible images (technically 1X1 GIF images), that
7236 are used to track users across websites, and collect information on them.
7237 As an HTML page is loaded by the browser, an embedded image tag causes the
7238 browser to contact a third-party site, disclosing the tracking information
7239 through the requested URL and/or cookies for that third-party domain, without
7240 the user ever becoming aware of the interaction with the third-party site.
7241 HTML-ized spam also uses a similar technique to verify email addresses.
7244 This filter removes the HTML code that loads such <quote>webbugs</quote>.
7250 <term><emphasis>tiny-textforms</emphasis></term>
7253 A rather special-purpose filter that can be used to enlarge textareas (those
7254 multi-line text boxes in web forms) and turn off hard word wrap in them.
7255 It was written for the sourceforge.net tracker system where such boxes are
7256 a nuisance, but it can be handy on other sites, too.
7259 It is not recommended to use this filter as a default.
7265 <term><emphasis>jumping-windows</emphasis></term>
7268 Many consider windows that move, or resize themselves to be abusive. This filter
7269 neutralizes the related JavaScript code. Note that some sites might not display
7270 or behave as intended when using this filter. Use with caution.
7276 <term><emphasis>frameset-borders</emphasis></term>
7279 Some web designers seem to assume that everyone in the world will view their
7280 web sites using the same browser brand and version, screen resolution etc,
7281 because only that assumption could explain why they'd use static frame sizes,
7282 yet prevent their frames from being resized by the user, should they be too
7283 small to show their whole content.
7286 This filter removes the related HTML code. It should only be applied to sites
7293 <term><emphasis>demoronizer</emphasis></term>
7296 Many Microsoft products that generate HTML use non-standard extensions (read:
7297 violations) of the ISO 8859-1 aka Latin-1 character set. This can cause those
7298 HTML documents to display with errors on standard-compliant platforms.
7301 This filter translates the MS-only characters into Latin-1 equivalents.
7302 It is not necessary when using MS products, and will cause corruption of
7303 all documents that use 8-bit character sets other than Latin-1. It's mostly
7304 worthwhile for Europeans on non-MS platforms, if weird garbage characters
7305 sometimes appear on some pages, or user agents that don't correct for this on
7308 My version of Mozilla (ancient) shows litte square boxes for quote
7309 characters, and apostrophes on moronized pages. So many pages have this, I
7310 can read them fine now. HB 08/27/06
7317 <term><emphasis>shockwave-flash</emphasis></term>
7320 A filter for shockwave haters. As the name suggests, this filter strips code
7321 out of web pages that is used to embed shockwave flash objects.
7329 <term><emphasis>quicktime-kioskmode</emphasis></term>
7332 Change HTML code that embeds Quicktime objects so that kioskmode, which
7333 prevents saving, is disabled.
7339 <term><emphasis>fun</emphasis></term>
7342 Text replacements for subversive browsing fun. Make fun of your favorite
7343 Monopolist or play buzzword bingo.
7349 <term><emphasis>crude-parental</emphasis></term>
7352 A demonstration-only filter that shows how <application>Privoxy</application>
7353 can be used to delete web content on a keyword basis.
7359 <term><emphasis>ie-exploits</emphasis></term>
7362 An experimental collection of text replacements to disable malicious HTML and JavaScript
7363 code that exploits known security holes in Internet Explorer.
7366 Presently, it only protects against Nimda and a cross-site scripting bug, and
7367 would need active maintenance to provide more substantial protection.
7373 <term><emphasis>site-specifics</emphasis></term>
7376 Some web sites have very specific problems, the cure for which doesn't apply
7377 anywhere else, or could even cause damage on other sites.
7380 This is a collection of such site-specific cures which should only be applied
7381 to the sites they were intended for, which is what the supplied
7382 <filename>default.action</filename> file does. Users shouldn't need to change
7383 anything regarding this filter.
7389 <term><emphasis>google</emphasis></term>
7392 A CSS based block for Google text ads. Also removes a width limitation
7393 and the toolbar advertisement.
7399 <term><emphasis>yahoo</emphasis></term>
7402 Another CSS based block, this time for Yahoo text ads. And removes
7403 a width limitation as well.
7409 <term><emphasis>msn</emphasis></term>
7412 Another CSS based block, this time for MSN text ads. And removes
7413 tracking URLs, as well as a width limitation.
7419 <term><emphasis>blogspot</emphasis></term>
7422 Cleans up some Blogspot blogs. Read the fine print before using this one!
7425 This filter also intentionally removes some navigation stuff and sets the
7426 page width to 100%. As a result, some rounded <quote>corners</quote> would
7427 appear to early or not at all and as fixing this would require a browser
7428 that understands background-size (CSS3), they are removed instead.
7434 <term><emphasis>xml-to-html</emphasis></term>
7437 Server-header filter to change the Content-Type from xml to html.
7443 <term><emphasis>html-to-xml</emphasis></term>
7446 Server-header filter to change the Content-Type from html to xml.
7452 <term><emphasis>no-ping</emphasis></term>
7455 Removes the non-standard <literal>ping</literal> attribute from
7456 anchor and area HTML tags.
7462 <term><emphasis>hide-tor-exit-notation</emphasis></term>
7465 Client-header filter to remove the <command>Tor</command> exit node notation
7466 found in Host and Referer headers.
7469 If &my-app; and <command>Tor</command> are chained and &my-app;
7470 is configured to use socks4a, one can use <quote>http://www.example.org.foobar.exit/</quote>
7471 to access the host <quote>www.example.org</quote> through the
7472 <command>Tor</command> exit node <quote>foobar</quote>.
7475 As the HTTP client isn't aware of this notation, it treats the
7476 whole string <quote>www.example.org.foobar.exit</quote> as host and uses it
7477 for the <quote>Host</quote> and <quote>Referer</quote> headers. From the
7478 server's point of view the resulting headers are invalid and can cause problems.
7481 An invalid <quote>Referer</quote> header can trigger <quote>hot-linking</quote>
7482 protections, an invalid <quote>Host</quote> header will make it impossible for
7483 the server to find the right vhost (several domains hosted on the same IP address).
7486 This client-header filter removes the <quote>foo.exit</quote> part in those headers
7487 to prevent the mentioned problems. Note that it only modifies
7488 the HTTP headers, it doesn't make it impossible for the server
7489 to detect your <command>Tor</command> exit node based on the IP address
7490 the request is coming from.
7497 <term><emphasis> </emphasis></term>
7510 <!-- ~~~~~~~~ New section Header ~~~~~~~~~ -->
7511 <sect2 id="external-filter-syntax"><title>External filter syntax</title>
7513 External filters are scripts or programs that can modify the content in
7514 case common <literal><link linkend="filter">filters</link></literal>
7515 aren't powerful enough.
7518 External filters can be written in any language the platform &my-app; runs
7522 They are controlled with the
7523 <literal><link linkend="external-filter">external-filter</link></literal> action
7524 and have to be defined in the <literal><link linkend="filterfile">filterfile</link></literal>
7528 The header looks like any other filter, but instead of pcrs jobs, external
7529 filters contain a single job which can be a program or a shell script (which
7530 may call other scripts or programs).
7533 External filters read the content from STDIN and write the rewritten
7534 content to STDOUT. The environment variables PRIVOXY_URL, PRIVOXY_PATH,
7535 PRIVOXY_HOST, PRIVOXY_ORIGIN can be used to get some details about the
7539 &my-app; will temporary store the content to filter in the
7540 <literal><link linkend="temporary-directory">temporary-directory</link></literal>.
7544 EXTERNAL-FILTER: cat Pointless example filter that doesn't actually modify the content
7547 # Incorrect reimplementation of the filter above in POSIX shell.
7549 # Note that it's a single job that spans multiple lines, the line
7550 # breaks are not passed to the shell, thus the semicolons are required.
7552 # If the script isn't trivial, it is recommended to put it into an external file.
7554 # In general, writing external filters entirely in POSIX shell is not
7555 # considered a good idea.
7556 EXTERNAL-FILTER: cat2 Pointless example filter that despite its name may actually modify the content
7562 EXTERNAL-FILTER: rotate-image Rotate an image by 180 degree. Test filter with limited value.
7563 /usr/local/bin/convert - -rotate 180 -
7565 EXTERNAL-FILTER: citation-needed Adds a "[citation needed]" tag to an image. The coordinates may need adjustment.
7566 /usr/local/bin/convert - -pointsize 16 -fill white -annotate +17+418 "[citation needed]" -
7572 Currently external filters are executed with &my-app;'s privileges!
7573 Only use external filters you understand and trust.
7577 External filters are experimental and the syntax may change in the future.
7583 <!-- ~ End section ~ -->
7587 <!-- ~~~~~ New section ~~~~~ -->
7589 <sect1 id="templates">
7590 <title>Privoxy's Template Files</title>
7592 All <application>Privoxy</application> built-in pages, i.e. error pages such as the
7593 <ulink url="http://show-the-404-error.page"><quote>404 - No Such Domain</quote>
7594 error page</ulink>, the <ulink
7595 url="http://ads.bannerserver.example.com/nasty-ads/sponsor.html"><quote>BLOCKED</quote>
7597 and all pages of its <ulink url="http://config.privoxy.org/">web-based
7598 user interface</ulink>, are generated from <emphasis>templates</emphasis>.
7599 (<application>Privoxy</application> must be running for the above links to work as
7604 These templates are stored in a subdirectory of the <link linkend="confdir">configuration
7605 directory</link> called <filename>templates</filename>. On Unixish platforms,
7607 <ulink url="file:///etc/privoxy/templates/"><filename>/etc/privoxy/templates/</filename></ulink>.
7611 The templates are basically normal HTML files, but with place-holders (called symbols
7612 or exports), which <application>Privoxy</application> fills at run time. It
7613 is possible to edit the templates with a normal text editor, should you want
7614 to customize them. (<emphasis>Not recommended for the casual
7615 user</emphasis>). Should you create your own custom templates, you should use
7616 the <filename>config</filename> setting <link linkend="templdir">templdir</link>
7617 to specify an alternate location, so your templates do not get overwritten
7621 Note that just like in configuration files, lines starting
7622 with <literal>#</literal> are ignored when the templates are filled in.
7626 The place-holders are of the form <literal>@name@</literal>, and you will
7627 find a list of available symbols, which vary from template to template,
7628 in the comments at the start of each file. Note that these comments are not
7629 always accurate, and that it's probably best to look at the existing HTML
7630 code to find out which symbols are supported and what they are filled in with.
7634 A special application of this substitution mechanism is to make whole
7635 blocks of HTML code disappear when a specific symbol is set. We use this
7636 for many purposes, one of them being to include the beta warning in all
7637 our user interface (CGI) pages when <application>Privoxy</application>
7638 is in an alpha or beta development stage:
7643 <!-- @if-unstable-start -->
7645 ... beta warning HTML code goes here ...
7647 <!-- if-unstable-end@ --></screen>
7651 If the "unstable" symbol is set, everything in between and including
7652 <literal>@if-unstable-start</literal> and <literal>if-unstable-end@</literal>
7653 will disappear, leaving nothing but an empty comment:
7657 <screen><!-- --></screen>
7661 There's also an if-then-else construct and an <literal>#include</literal>
7662 mechanism, but you'll sure find out if you are inclined to edit the
7667 All templates refer to a style located at
7668 <ulink url="http://config.privoxy.org/send-stylesheet"><literal>http://config.privoxy.org/send-stylesheet</literal></ulink>.
7669 This is, of course, locally served by <application>Privoxy</application>
7670 and the source for it can be found and edited in the
7671 <filename>cgi-style.css</filename> template.
7676 <!-- ~ End section ~ -->
7680 <!-- ~~~~~ New section ~~~~~ -->
7682 <sect1 id="contact"><title>Contacting the Developers, Bug Reporting and Feature
7685 <!-- Include contacting.sgml boilerplate: -->
7687 <!-- end boilerplate -->
7691 <!-- ~ End section ~ -->
7694 <!-- ~~~~~ New section ~~~~~ -->
7695 <sect1 id="copyright"><title>Privoxy Copyright, License and History</title>
7697 <!-- Include copyright.sgml: -->
7699 <!-- end copyright -->
7702 <application>Privoxy</application> is free software; you can
7703 redistribute it and/or modify it under the terms of the
7704 <citetitle>GNU General Public License</citetitle>, version 2,
7705 as published by the Free Software Foundation and included in
7709 <!-- ~~~~~ New section ~~~~~ -->
7710 <sect2 id="license"><title>License</title>
7712 <screen><![ RCDATA [ &GPLv2; ]]></screen>
7716 <!-- ~ End section ~ -->
7719 <!-- ~~~~~ New section ~~~~~ -->
7721 <sect2 id="history"><title>History</title>
7722 <!-- Include history.sgml: -->
7724 <!-- end history -->
7727 <sect2 id="authors"><title>Authors</title>
7728 <!-- Include p-authors.sgml: -->
7730 <!-- end authors -->
7735 <!-- ~ End section ~ -->
7738 <!-- ~~~~~ New section ~~~~~ -->
7739 <sect1 id="seealso"><title>See Also</title>
7740 <!-- Include seealso.sgml: -->
7742 <!-- end seealso -->
7747 <!-- ~~~~~ New section ~~~~~ -->
7748 <sect1 id="appendix"><title>Appendix</title>
7751 <!-- ~~~~~ New section ~~~~~ -->
7753 <title>Regular Expressions</title>
7755 <application>Privoxy</application> uses Perl-style <quote>regular
7756 expressions</quote> in its <link linkend="actions-file">actions
7757 files</link> and <link linkend="filter-file">filter file</link>,
7758 through the <ulink url="http://www.pcre.org/">PCRE</ulink> and
7761 <ulink url="http://www.oesterhelt.org/pcrs/">PCRS</ulink> libraries.
7763 <application>PCRS</application> libraries.
7767 If you are reading this, you probably don't understand what <quote>regular
7768 expressions</quote> are, or what they can do. So this will be a very brief
7769 introduction only. A full explanation would require a <ulink
7770 url="http://www.oreilly.com/catalog/regex/">book</ulink> ;-)
7774 Regular expressions provide a language to describe patterns that can be
7775 run against strings of characters (letter, numbers, etc), to see if they
7776 match the string or not. The patterns are themselves (sometimes complex)
7777 strings of literal characters, combined with wild-cards, and other special
7778 characters, called meta-characters. The <quote>meta-characters</quote> have
7779 special meanings and are used to build complex patterns to be matched against.
7780 Perl Compatible Regular Expressions are an especially convenient
7781 <quote>dialect</quote> of the regular expression language.
7785 To make a simple analogy, we do something similar when we use wild-card
7786 characters when listing files with the <command>dir</command> command in DOS.
7787 <literal>*.*</literal> matches all filenames. The <quote>special</quote>
7788 character here is the asterisk which matches any and all characters. We can be
7789 more specific and use <literal>?</literal> to match just individual
7790 characters. So <quote>dir file?.text</quote> would match
7791 <quote>file1.txt</quote>, <quote>file2.txt</quote>, etc. We are pattern
7792 matching, using a similar technique to <quote>regular expressions</quote>!
7796 Regular expressions do essentially the same thing, but are much, much more
7797 powerful. There are many more <quote>special characters</quote> and ways of
7798 building complex patterns however. Let's look at a few of the common ones,
7799 and then some examples:
7804 <emphasis>.</emphasis> - Matches any single character, e.g. <quote>a</quote>,
7805 <quote>A</quote>, <quote>4</quote>, <quote>:</quote>, or <quote>@</quote>.
7807 </simplelist></para>
7811 <emphasis>?</emphasis> - The preceding character or expression is matched ZERO or ONE
7814 </simplelist></para>
7818 <emphasis>+</emphasis> - The preceding character or expression is matched ONE or MORE
7821 </simplelist></para>
7825 <emphasis>*</emphasis> - The preceding character or expression is matched ZERO or MORE
7828 </simplelist></para>
7832 <emphasis>\</emphasis> - The <quote>escape</quote> character denotes that
7833 the following character should be taken literally. This is used where one of the
7834 special characters (e.g. <quote>.</quote>) needs to be taken literally and
7835 not as a special meta-character. Example: <quote>example\.com</quote>, makes
7836 sure the period is recognized only as a period (and not expanded to its
7837 meta-character meaning of any single character).
7839 </simplelist></para>
7843 <emphasis>[ ]</emphasis> - Characters enclosed in brackets will be matched if
7844 any of the enclosed characters are encountered. For instance, <quote>[0-9]</quote>
7845 matches any numeric digit (zero through nine). As an example, we can combine
7846 this with <quote>+</quote> to match any digit one of more times: <quote>[0-9]+</quote>.
7848 </simplelist></para>
7852 <emphasis>( )</emphasis> - parentheses are used to group a sub-expression,
7853 or multiple sub-expressions.
7855 </simplelist></para>
7859 <emphasis>|</emphasis> - The <quote>bar</quote> character works like an
7860 <quote>or</quote> conditional statement. A match is successful if the
7861 sub-expression on either side of <quote>|</quote> matches. As an example:
7862 <quote>/(this|that) example/</quote> uses grouping and the bar character
7863 and would match either <quote>this example</quote> or <quote>that
7864 example</quote>, and nothing else.
7866 </simplelist></para>
7869 These are just some of the ones you are likely to use when matching URLs with
7870 <application>Privoxy</application>, and is a long way from a definitive
7871 list. This is enough to get us started with a few simple examples which may
7872 be more illuminating:
7876 <emphasis><literal>/.*/banners/.*</literal></emphasis> - A simple example
7877 that uses the common combination of <quote>.</quote> and <quote>*</quote> to
7878 denote any character, zero or more times. In other words, any string at all.
7879 So we start with a literal forward slash, then our regular expression pattern
7880 (<quote>.*</quote>) another literal forward slash, the string
7881 <quote>banners</quote>, another forward slash, and lastly another
7882 <quote>.*</quote>. We are building
7883 a directory path here. This will match any file with the path that has a
7884 directory named <quote>banners</quote> in it. The <quote>.*</quote> matches
7885 any characters, and this could conceivably be more forward slashes, so it
7886 might expand into a much longer looking path. For example, this could match:
7887 <quote>/eye/hate/spammers/banners/annoy_me_please.gif</quote>, or just
7888 <quote>/banners/annoying.html</quote>, or almost an infinite number of other
7889 possible combinations, just so it has <quote>banners</quote> in the path
7894 And now something a little more complex:
7898 <emphasis><literal>/.*/adv((er)?ts?|ertis(ing|ements?))?/</literal></emphasis> -
7899 We have several literal forward slashes again (<quote>/</quote>), so we are
7900 building another expression that is a file path statement. We have another
7901 <quote>.*</quote>, so we are matching against any conceivable sub-path, just so
7902 it matches our expression. The only true literal that <emphasis>must
7903 match</emphasis> our pattern is <application>adv</application>, together with
7904 the forward slashes. What comes after the <quote>adv</quote> string is the
7909 Remember the <quote>?</quote> means the preceding expression (either a
7910 literal character or anything grouped with <quote>(...)</quote> in this case)
7911 can exist or not, since this means either zero or one match. So
7912 <quote>((er)?ts?|ertis(ing|ements?))</quote> is optional, as are the
7913 individual sub-expressions: <quote>(er)</quote>,
7914 <quote>(ing|ements?)</quote>, and the <quote>s</quote>. The <quote>|</quote>
7915 means <quote>or</quote>. We have two of those. For instance,
7916 <quote>(ing|ements?)</quote>, can expand to match either <quote>ing</quote>
7917 <emphasis>OR</emphasis> <quote>ements?</quote>. What is being done here, is an
7918 attempt at matching as many variations of <quote>advertisement</quote>, and
7919 similar, as possible. So this would expand to match just <quote>adv</quote>,
7920 or <quote>advert</quote>, or <quote>adverts</quote>, or
7921 <quote>advertising</quote>, or <quote>advertisement</quote>, or
7922 <quote>advertisements</quote>. You get the idea. But it would not match
7923 <quote>advertizements</quote> (with a <quote>z</quote>). We could fix that by
7924 changing our regular expression to:
7925 <quote>/.*/adv((er)?ts?|erti(s|z)(ing|ements?))?/</quote>, which would then match
7930 <emphasis><literal>/.*/advert[0-9]+\.(gif|jpe?g)</literal></emphasis> - Again
7931 another path statement with forward slashes. Anything in the square brackets
7932 <quote>[ ]</quote> can be matched. This is using <quote>0-9</quote> as a
7933 shorthand expression to mean any digit one through nine. It is the same as
7934 saying <quote>0123456789</quote>. So any digit matches. The <quote>+</quote>
7935 means one or more of the preceding expression must be included. The preceding
7936 expression here is what is in the square brackets -- in this case, any digit
7937 one through nine. Then, at the end, we have a grouping: <quote>(gif|jpe?g)</quote>.
7938 This includes a <quote>|</quote>, so this needs to match the expression on
7939 either side of that bar character also. A simple <quote>gif</quote> on one side, and the other
7940 side will in turn match either <quote>jpeg</quote> or <quote>jpg</quote>,
7941 since the <quote>?</quote> means the letter <quote>e</quote> is optional and
7942 can be matched once or not at all. So we are building an expression here to
7943 match image GIF or JPEG type image file. It must include the literal
7944 string <quote>advert</quote>, then one or more digits, and a <quote>.</quote>
7945 (which is now a literal, and not a special character, since it is escaped
7946 with <quote>\</quote>), and lastly either <quote>gif</quote>, or
7947 <quote>jpeg</quote>, or <quote>jpg</quote>. Some possible matches would
7948 include: <quote>//advert1.jpg</quote>,
7949 <quote>/nasty/ads/advert1234.gif</quote>,
7950 <quote>/banners/from/hell/advert99.jpg</quote>. It would not match
7951 <quote>advert1.gif</quote> (no leading slash), or
7952 <quote>/adverts232.jpg</quote> (the expression does not include an
7953 <quote>s</quote>), or <quote>/advert1.jsp</quote> (<quote>jsp</quote> is not
7954 in the expression anywhere).
7958 We are barely scratching the surface of regular expressions here so that you
7959 can understand the default <application>Privoxy</application>
7960 configuration files, and maybe use this knowledge to customize your own
7961 installation. There is much, much more that can be done with regular
7962 expressions. Now that you know enough to get started, you can learn more on
7967 More reading on Perl Compatible Regular expressions:
7968 <ulink url="http://perldoc.perl.org/perlre.html">http://perldoc.perl.org/perlre.html</ulink>
7972 For information on regular expression based substitutions and their applications
7973 in filters, please see the <link linkend="filter-file">filter file tutorial</link>
7978 <!-- ~ End section ~ -->
7981 <!-- ~~~~~ New section ~~~~~ -->
7982 <sect2 id="internal-pages">
7983 <title>Privoxy's Internal Pages</title>
7986 Since <application>Privoxy</application> proxies each requested
7987 web page, it is easy for <application>Privoxy</application> to
7988 trap certain special URLs. In this way, we can talk directly to
7989 <application>Privoxy</application>, and see how it is
7990 configured, see how our rules are being applied, change these
7991 rules and other configuration options, and even turn
7992 <application>Privoxy's</application> filtering off, all with
7998 The URLs listed below are the special ones that allow direct access
7999 to <application>Privoxy</application>. Of course,
8000 <application>Privoxy</application> must be running to access these. If
8001 not, you will get a friendly error message. Internet access is not
8014 <ulink url="http://config.privoxy.org/">http://config.privoxy.org/</ulink>
8018 There is a shortcut: <ulink url="http://p.p/">http://p.p/</ulink> (But it
8019 doesn't provide a fall-back to a real page, in case the request is not
8020 sent through <application>Privoxy</application>)
8026 Show information about the current configuration, including viewing and
8027 editing of actions files:
8031 <ulink url="http://config.privoxy.org/show-status">http://config.privoxy.org/show-status</ulink>
8038 Show the source code version numbers:
8042 <ulink url="http://config.privoxy.org/show-version">http://config.privoxy.org/show-version</ulink>
8049 Show the browser's request headers:
8053 <ulink url="http://config.privoxy.org/show-request">http://config.privoxy.org/show-request</ulink>
8060 Show which actions apply to a URL and why:
8064 <ulink url="http://config.privoxy.org/show-url-info">http://config.privoxy.org/show-url-info</ulink>
8071 Toggle Privoxy on or off. This feature can be turned off/on in the main
8072 <filename>config</filename> file. When toggled <quote>off</quote>, <quote>Privoxy</quote>
8073 continues to run, but only as a pass-through proxy, with no actions taking
8078 <ulink url="http://config.privoxy.org/toggle">http://config.privoxy.org/toggle</ulink>
8082 Short cuts. Turn off, then on:
8086 <ulink url="http://config.privoxy.org/toggle?set=disable">http://config.privoxy.org/toggle?set=disable</ulink>
8091 <ulink url="http://config.privoxy.org/toggle?set=enable">http://config.privoxy.org/toggle?set=enable</ulink>
8102 <!-- ~~~~~ New section ~~~~~ -->
8104 <title>Chain of Events</title>
8106 Let's take a quick look at how some of <application>Privoxy's</application>
8107 core features are triggered, and the ensuing sequence of events when a web
8108 page is requested by your browser:
8115 First, your web browser requests a web page. The browser knows to send
8116 the request to <application>Privoxy</application>, which will in turn,
8117 relay the request to the remote web server after passing the following
8123 <application>Privoxy</application> traps any request for its own internal CGI
8124 pages (e.g <ulink url="http://p.p/">http://p.p/</ulink>) and sends the CGI page back to the browser.
8129 Next, <application>Privoxy</application> checks to see if the URL
8131 linkend="BLOCK"><quote>+block</quote></link> patterns. If
8132 so, the URL is then blocked, and the remote web server will not be contacted.
8133 <link linkend="HANDLE-AS-IMAGE"><quote>+handle-as-image</quote></link>
8135 <link linkend="HANDLE-AS-EMPTY-DOCUMENT"><quote>+handle-as-empty-document</quote></link>
8136 are then checked, and if there is no match, an
8137 HTML <quote>BLOCKED</quote> page is sent back to the browser. Otherwise, if
8138 it does match, an image is returned for the former, and an empty text
8139 document for the latter. The type of image would depend on the setting of
8140 <link linkend="SET-IMAGE-BLOCKER"><quote>+set-image-blocker</quote></link>
8141 (blank, checkerboard pattern, or an HTTP redirect to an image elsewhere).
8146 Untrusted URLs are blocked. If URLs are being added to the
8147 <filename>trust</filename> file, then that is done.
8152 If the URL pattern matches the <link
8153 linkend="FAST-REDIRECTS"><quote>+fast-redirects</quote></link> action,
8154 it is then processed. Unwanted parts of the requested URL are stripped.
8159 Now the rest of the client browser's request headers are processed. If any
8160 of these match any of the relevant actions (e.g. <link
8161 linkend="HIDE-USER-AGENT"><quote>+hide-user-agent</quote></link>,
8162 etc.), headers are suppressed or forged as determined by these actions and
8168 Now the web server starts sending its response back (i.e. typically a web
8174 First, the server headers are read and processed to determine, among other
8175 things, the MIME type (document type) and encoding. The headers are then
8176 filtered as determined by the
8177 <link linkend="CRUNCH-INCOMING-COOKIES"><quote>+crunch-incoming-cookies</quote></link>,
8178 <link linkend="SESSION-COOKIES-ONLY"><quote>+session-cookies-only</quote></link>,
8179 and <link linkend="DOWNGRADE-HTTP-VERSION"><quote>+downgrade-http-version</quote></link>
8185 If any <link linkend="FILTER"><quote>+filter</quote></link> action
8187 linkend="DEANIMATE-GIFS"><quote>+deanimate-gifs</quote></link>
8188 action applies (and the document type fits the action), the rest of the page is
8189 read into memory (up to a configurable limit). Then the filter rules (from
8190 <filename>default.filter</filename> and any other filter files) are
8191 processed against the buffered content. Filters are applied in the order
8192 they are specified in one of the filter files. Animated GIFs, if present,
8193 are reduced to either the first or last frame, depending on the action
8194 setting.The entire page, which is now filtered, is then sent by
8195 <application>Privoxy</application> back to your browser.
8198 If neither a <link linkend="FILTER"><quote>+filter</quote></link> action
8200 linkend="DEANIMATE-GIFS"><quote>+deanimate-gifs</quote></link>
8201 matches, then <application>Privoxy</application> passes the raw data through
8202 to the client browser as it becomes available.
8207 As the browser receives the now (possibly filtered) page content, it
8208 reads and then requests any URLs that may be embedded within the page
8209 source, e.g. ad images, stylesheets, JavaScript, other HTML documents (e.g.
8210 frames), sounds, etc. For each of these objects, the browser issues a
8211 separate request (this is easily viewable in <application>Privoxy's</application>
8212 logs). And each such request is in turn processed just as above. Note that a
8213 complex web page will have many, many such embedded URLs. If these
8214 secondary requests are to a different server, then quite possibly a very
8215 differing set of actions is triggered.
8222 NOTE: This is somewhat of a simplistic overview of what happens with each URL
8223 request. For the sake of brevity and simplicity, we have focused on
8224 <application>Privoxy's</application> core features only.
8230 <!-- ~~~~~ New section ~~~~~ -->
8231 <sect2 id="actionsanat">
8232 <title>Troubleshooting: Anatomy of an Action</title>
8235 The way <application>Privoxy</application> applies
8236 <link linkend="ACTIONS">actions</link> and <link linkend="FILTER">filters</link>
8237 to any given URL can be complex, and not always so
8238 easy to understand what is happening. And sometimes we need to be able to
8239 <emphasis>see</emphasis> just what <application>Privoxy</application> is
8240 doing. Especially, if something <application>Privoxy</application> is doing
8241 is causing us a problem inadvertently. It can be a little daunting to look at
8242 the actions and filters files themselves, since they tend to be filled with
8243 <link linkend="regex">regular expressions</link> whose consequences are not
8248 One quick test to see if <application>Privoxy</application> is causing a problem
8249 or not, is to disable it temporarily. This should be the first troubleshooting
8250 step (be sure to flush caches afterward!). Looking at the
8251 logs is a good idea too. (Note that both the toggle feature and logging are
8252 enabled via <filename>config</filename> file settings, and may need to be
8253 turned <quote>on</quote>.)
8256 Another easy troubleshooting step to try is if you have done any
8257 customization of your installation, revert back to the installed
8258 defaults and see if that helps. There are times the developers get complaints
8259 about one thing or another, and the problem is more related to a customized
8260 configuration issue.
8264 <application>Privoxy</application> also provides the
8265 <ulink url="http://config.privoxy.org/show-url-info">http://config.privoxy.org/show-url-info</ulink>
8266 page that can show us very specifically how <application>actions</application>
8267 are being applied to any given URL. This is a big help for troubleshooting.
8271 First, enter one URL (or partial URL) at the prompt, and then
8272 <application>Privoxy</application> will tell us
8273 how the current configuration will handle it. This will not
8274 help with filtering effects (i.e. the <link
8275 linkend="FILTER"><quote>+filter</quote></link> action) from
8276 one of the filter files since this is handled very
8277 differently and not so easy to trap! It also will not tell you about any other
8278 URLs that may be embedded within the URL you are testing. For instance, images
8279 such as ads are expressed as URLs within the raw page source of HTML pages. So
8280 you will only get info for the actual URL that is pasted into the prompt area
8281 -- not any sub-URLs. If you want to know about embedded URLs like ads, you
8282 will have to dig those out of the HTML source. Use your browser's <quote>View
8283 Page Source</quote> option for this. Or right click on the ad, and grab the
8288 Let's try an example, <ulink url="http://google.com">google.com</ulink>,
8289 and look at it one section at a time in a sample configuration (your real
8290 configuration may vary):
8295 Matches for http://www.google.com:
8297 In file: default.action <guibutton>[ View ]</guibutton> <guibutton>[ Edit ]</guibutton>
8299 {+change-x-forwarded-for{block}
8300 +deanimate-gifs {last}
8301 +fast-redirects {check-decoded-url}
8302 +filter {refresh-tags}
8303 +filter {img-reorder}
8304 +filter {banners-by-size}
8306 +filter {jumping-windows}
8307 +filter {ie-exploits}
8308 +hide-from-header {block}
8309 +hide-referrer {forge}
8310 +session-cookies-only
8311 +set-image-blocker {pattern}
8314 { -session-cookies-only }
8320 In file: user.action <guibutton>[ View ]</guibutton> <guibutton>[ Edit ]</guibutton>
8321 (no matches in this file)
8326 This is telling us how we have defined our
8327 <link linkend="ACTIONS"><quote>actions</quote></link>, and
8328 which ones match for our test case, <quote>google.com</quote>.
8329 Displayed is all the actions that are available to us. Remember,
8330 the <literal>+</literal> sign denotes <quote>on</quote>. <literal>-</literal>
8331 denotes <quote>off</quote>. So some are <quote>on</quote> here, but many
8332 are <quote>off</quote>. Each example we try may provide a slightly different
8333 end result, depending on our configuration directives.
8337 is for our <filename>default.action</filename> file. The large, multi-line
8338 listing, is how the actions are set to match for all URLs, i.e. our default
8339 settings. If you look at your <quote>actions</quote> file, this would be the
8340 section just below the <quote>aliases</quote> section near the top. This
8341 will apply to all URLs as signified by the single forward slash at the end
8342 of the listing -- <quote> / </quote>.
8346 But we have defined additional actions that would be exceptions to these general
8347 rules, and then we list specific URLs (or patterns) that these exceptions
8348 would apply to. Last match wins. Just below this then are two explicit
8349 matches for <quote>.google.com</quote>. The first is negating our previous
8350 cookie setting, which was for <link
8351 linkend="SESSION-COOKIES-ONLY"><quote>+session-cookies-only</quote></link>
8352 (i.e. not persistent). So we will allow persistent cookies for google, at
8353 least that is how it is in this example. The second turns
8354 <emphasis>off</emphasis> any <link
8355 linkend="FAST-REDIRECTS"><quote>+fast-redirects</quote></link>
8356 action, allowing this to take place unmolested. Note that there is a leading
8357 dot here -- <quote>.google.com</quote>. This will match any hosts and
8358 sub-domains, in the google.com domain also, such as
8359 <quote>www.google.com</quote> or <quote>mail.google.com</quote>. But it would not
8360 match <quote>www.google.de</quote>! So, apparently, we have these two actions
8361 defined as exceptions to the general rules at the top somewhere in the lower
8362 part of our <filename>default.action</filename> file, and
8363 <quote>google.com</quote> is referenced somewhere in these latter sections.
8367 Then, for our <filename>user.action</filename> file, we again have no hits.
8368 So there is nothing google-specific that we might have added to our own, local
8369 configuration. If there was, those actions would over-rule any actions from
8370 previously processed files, such as <filename>default.action</filename>.
8371 <filename>user.action</filename> typically has the last word. This is the
8372 best place to put hard and fast exceptions,
8376 And finally we pull it all together in the bottom section and summarize how
8377 <application>Privoxy</application> is applying all its <quote>actions</quote>
8378 to <quote>google.com</quote>:
8389 +change-x-forwarded-for{block}
8390 -client-header-filter{hide-tor-exit-notation}
8391 -content-type-overwrite
8392 -crunch-client-header
8393 -crunch-if-none-match
8394 -crunch-incoming-cookies
8395 -crunch-outgoing-cookies
8396 -crunch-server-header
8397 +deanimate-gifs {last}
8398 -downgrade-http-version
8401 -filter {content-cookies}
8402 -filter {all-popups}
8403 -filter {banners-by-link}
8404 -filter {tiny-textforms}
8405 -filter {frameset-borders}
8406 -filter {demoronizer}
8407 -filter {shockwave-flash}
8408 -filter {quicktime-kioskmode}
8410 -filter {crude-parental}
8411 -filter {site-specifics}
8412 -filter {js-annoyances}
8413 -filter {html-annoyances}
8414 +filter {refresh-tags}
8415 -filter {unsolicited-popups}
8416 +filter {img-reorder}
8417 +filter {banners-by-size}
8419 +filter {jumping-windows}
8420 +filter {ie-exploits}
8427 -handle-as-empty-document
8429 -hide-accept-language
8430 -hide-content-disposition
8431 +hide-from-header {block}
8432 -hide-if-modified-since
8433 +hide-referrer {forge}
8436 -overwrite-last-modified
8437 -prevent-compression
8439 -server-header-filter{xml-to-html}
8440 -server-header-filter{html-to-xml}
8441 -session-cookies-only
8442 +set-image-blocker {pattern} </screen>
8446 Notice the only difference here to the previous listing, is to
8447 <quote>fast-redirects</quote> and <quote>session-cookies-only</quote>,
8448 which are activated specifically for this site in our configuration,
8449 and thus show in the <quote>Final Results</quote>.
8453 Now another example, <quote>ad.doubleclick.net</quote>:
8459 { +block{Domains starts with "ad"} }
8462 { +block{Domain contains "ad"} }
8465 { +block{Doubleclick banner server} +handle-as-image }
8466 .[a-vx-z]*.doubleclick.net
8471 We'll just show the interesting part here - the explicit matches. It is
8472 matched three different times. Two <quote>+block{}</quote> sections,
8473 and a <quote>+block{} +handle-as-image</quote>,
8474 which is the expanded form of one of our aliases that had been defined as:
8475 <quote>+block-as-image</quote>. (<link
8476 linkend="ALIASES"><quote>Aliases</quote></link> are defined in
8477 the first section of the actions file and typically used to combine more
8482 Any one of these would have done the trick and blocked this as an unwanted
8483 image. This is unnecessarily redundant since the last case effectively
8484 would also cover the first. No point in taking chances with these guys
8485 though ;-) Note that if you want an ad or obnoxious
8486 URL to be invisible, it should be defined as <quote>ad.doubleclick.net</quote>
8487 is done here -- as both a <link
8488 linkend="BLOCK"><quote>+block{}</quote></link>
8489 <emphasis>and</emphasis> an
8490 <link linkend="HANDLE-AS-IMAGE"><quote>+handle-as-image</quote></link>.
8491 The custom alias <quote><literal>+block-as-image</literal></quote> just
8492 simplifies the process and make it more readable.
8496 One last example. Let's try <quote>http://www.example.net/adsl/HOWTO/</quote>.
8497 This one is giving us problems. We are getting a blank page. Hmmm ...
8503 Matches for http://www.example.net/adsl/HOWTO/:
8505 In file: default.action <guibutton>[ View ]</guibutton> <guibutton>[ Edit ]</guibutton>
8509 +change-x-forwarded-for{block}
8510 -client-header-filter{hide-tor-exit-notation}
8511 -content-type-overwrite
8512 -crunch-client-header
8513 -crunch-if-none-match
8514 -crunch-incoming-cookies
8515 -crunch-outgoing-cookies
8516 -crunch-server-header
8518 -downgrade-http-version
8519 +fast-redirects {check-decoded-url}
8521 -filter {content-cookies}
8522 -filter {all-popups}
8523 -filter {banners-by-link}
8524 -filter {tiny-textforms}
8525 -filter {frameset-borders}
8526 -filter {demoronizer}
8527 -filter {shockwave-flash}
8528 -filter {quicktime-kioskmode}
8530 -filter {crude-parental}
8531 -filter {site-specifics}
8532 -filter {js-annoyances}
8533 -filter {html-annoyances}
8534 +filter {refresh-tags}
8535 -filter {unsolicited-popups}
8536 +filter {img-reorder}
8537 +filter {banners-by-size}
8539 +filter {jumping-windows}
8540 +filter {ie-exploits}
8547 -handle-as-empty-document
8549 -hide-accept-language
8550 -hide-content-disposition
8551 +hide-from-header{block}
8552 +hide-referer{forge}
8554 -overwrite-last-modified
8555 +prevent-compression
8557 -server-header-filter{xml-to-html}
8558 -server-header-filter{html-to-xml}
8559 +session-cookies-only
8560 +set-image-blocker{blank} }
8563 { +block{Path contains "ads".} +handle-as-image }
8569 Ooops, the <quote>/adsl/</quote> is matching <quote>/ads</quote> in our
8570 configuration! But we did not want this at all! Now we see why we get the
8571 blank page. It is actually triggering two different actions here, and
8572 the effects are aggregated so that the URL is blocked, and &my-app; is told
8573 to treat the block as if it were an image. But this is, of course, all wrong.
8574 We could now add a new action below this (or better in our own
8575 <filename>user.action</filename> file) that explicitly
8576 <emphasis>un</emphasis> blocks (
8577 <link linkend="BLOCK"><quote>{-block}</quote></link>) paths with
8578 <quote>adsl</quote> in them (remember, last match in the configuration
8579 wins). There are various ways to handle such exceptions. Example:
8591 Now the page displays ;-)
8592 Remember to flush your browser's caches when making these kinds of changes to
8593 your configuration to insure that you get a freshly delivered page! Or, try
8594 using <literal>Shift+Reload</literal>.
8598 But now what about a situation where we get no explicit matches like
8605 { +block{Path starts with "ads".} +handle-as-image }
8611 That actually was very helpful and pointed us quickly to where the problem
8612 was. If you don't get this kind of match, then it means one of the default
8613 rules in the first section of <filename>default.action</filename> is causing
8614 the problem. This would require some guesswork, and maybe a little trial and
8615 error to isolate the offending rule. One likely cause would be one of the
8616 <link linkend="FILTER"><quote>+filter</quote></link> actions.
8617 These tend to be harder to troubleshoot.
8618 Try adding the URL for the site to one of aliases that turn off
8619 <link linkend="FILTER"><quote>+filter</quote></link>:
8627 .worldpay.com # for quietpc.com
8635 <quote><literal>{ shop }</literal></quote> is an <quote>alias</quote> that expands to
8636 <quote><literal>{ -filter -session-cookies-only }</literal></quote>.
8637 Or you could do your own exception to negate filtering:
8645 # Disable ALL filter actions for sites in this section
8653 This would turn off all filtering for these sites. This is best
8654 put in <filename>user.action</filename>, for local site
8655 exceptions. Note that when a simple domain pattern is used by itself (without
8656 the subsequent path portion), all sub-pages within that domain are included
8657 automatically in the scope of the action.
8661 Images that are inexplicably being blocked, may well be hitting the
8662 <link linkend="FILTER-BANNERS-BY-SIZE"><quote>+filter{banners-by-size}</quote></link>
8664 that images of certain sizes are ad banners (works well
8665 <emphasis>most of the time</emphasis> since these tend to be standardized).
8669 <quote><literal>{ fragile }</literal></quote> is an alias that disables most
8670 actions that are the most likely to cause trouble. This can be used as a
8671 last resort for problem sites.
8677 # Handle with care: easy to break
8679 mybank.example.com</screen>
8684 <emphasis>Remember to flush caches!</emphasis> Note that the
8685 <literal>mail.google</literal> reference lacks the TLD portion (e.g.
8686 <quote>.com</quote>). This will effectively match any TLD with
8687 <literal>google</literal> in it, such as <literal>mail.google.de.</literal>,
8691 If this still does not work, you will have to go through the remaining
8692 actions one by one to find which one(s) is causing the problem.
8701 This program is free software; you can redistribute it
8702 and/or modify it under the terms of the GNU General
8703 Public License as published by the Free Software
8704 Foundation; either version 2 of the License, or (at
8705 your option) any later version.
8707 This program is distributed in the hope that it will
8708 be useful, but WITHOUT ANY WARRANTY; without even the
8709 implied warranty of MERCHANTABILITY or FITNESS FOR A
8710 PARTICULAR PURPOSE. See the GNU General Public
8711 License for more details.
8713 The GNU General Public License should be included with
8714 this file. If not, you can view it at
8715 http://www.gnu.org/copyleft/gpl.html
8716 or write to the Free Software Foundation, Inc.,
8717 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
projects / privoxy.git / blob