1 <!DOCTYPE article PUBLIC "-//OASIS//DTD DocBook V3.1//EN" [
2 <!entity % dummy "IGNORE">
3 <!entity supported SYSTEM "supported.sgml">
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11 <!entity license SYSTEM "license.sgml">
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13 <!entity p-authors SYSTEM "p-authors.sgml">
14 <!entity config SYSTEM "p-config.sgml">
15 <!entity changelog SYSTEM "changelog.sgml">
16 <!entity p-version "3.0.27">
17 <!entity p-status "UNRELEASED">
18 <!entity % p-authors-formal "INCLUDE"> <!-- include additional text, etc -->
19 <!entity % p-not-stable "INCLUDE">
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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 2.221 2017/05/20 09:27:54 fabiankeil Exp $
41 Copyright (C) 2001-2017 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; 2001-2017 by
61 <ulink url="https://www.privoxy.org/">Privoxy Developers</ulink>
65 <pubdate>$Id: user-manual.sgml,v 2.221 2017/05/20 09:27:54 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$</literal></term>
2278 This regular expression is conditional so it will match any page
2279 named <quote>index.html</quote> regardless of path which in this case can
2280 have one or more <quote>/'s</quote>. And this one must contain exactly
2281 <quote>.html</quote> (and end with that!).
2286 <term><literal>.example.com/(.*/)(ads|banners?|junk)</literal></term>
2289 This regular expression will match any path of <quote>example.com</quote>
2290 that contains any of the words <quote>ads</quote>, <quote>banner</quote>,
2291 <quote>banners</quote> (because of the <quote>?</quote>) or <quote>junk</quote>.
2292 The path does not have to end in these words, just contain them.
2293 The path has to contain at least two slashes (including the one at the beginning).
2298 <term><literal>.example.com/(.*/)(ads|banners?|junk)/.*\.(jpe?g|gif|png)$</literal></term>
2301 This is very much the same as above, except now it must end in either
2302 <quote>.jpg</quote>, <quote>.jpeg</quote>, <quote>.gif</quote> or <quote>.png</quote>. So this
2303 one is limited to common image formats.
2310 There are many, many good examples to be found in <filename>default.action</filename>,
2311 and more tutorials below in <link linkend="regex">Appendix on regular expressions</link>.
2316 <!-- ~ End section ~ -->
2319 <!-- ~~~~~ New section ~~~~~ -->
2320 <sect3 id="tag-pattern"><title>The Request Tag Pattern</title>
2323 Request tag patterns are used to change the applying actions based on the
2324 request's tags. Tags can be created based on HTTP headers with either
2325 the <link linkend="CLIENT-HEADER-TAGGER">client-header-tagger</link>
2326 or the <link linkend="SERVER-HEADER-TAGGER">server-header-tagger</link> action.
2330 Request tag patterns have to start with <quote>TAG:</quote>, so &my-app;
2331 can tell them apart from other patterns. Everything after the colon
2332 including white space, is interpreted as a regular expression with
2333 path pattern syntax, except that tag patterns aren't left-anchored
2334 automatically (&my-app; doesn't silently add a <quote>^</quote>,
2335 you have to do it yourself if you need it).
2339 To match all requests that are tagged with <quote>foo</quote>
2340 your pattern line should be <quote>TAG:^foo$</quote>,
2341 <quote>TAG:foo</quote> would work as well, but it would also
2342 match requests whose tags contain <quote>foo</quote> somewhere.
2343 <quote>TAG: foo</quote> wouldn't work as it requires white space.
2347 Sections can contain URL and request tag patterns at the same time,
2348 but request tag patterns are checked after the URL patterns and thus
2349 always overrule them, even if they are located before the URL patterns.
2353 Once a new request tag is added, Privoxy checks right away if it's matched by one
2354 of the request tag patterns and updates the action settings accordingly. As a result
2355 request tags can be used to activate other tagger actions, as long as these other
2356 taggers look for headers that haven't already be parsed.
2360 For example you could tag client requests which use the
2361 <literal>POST</literal> method,
2362 then use this tag to activate another tagger that adds a tag if cookies
2363 are sent, and then use a block action based on the cookie tag. This allows
2364 the outcome of one action, to be input into a subsequent action. However if
2365 you'd reverse the position of the described taggers, and activated the
2366 method tagger based on the cookie tagger, no method tags would be created.
2367 The method tagger would look for the request line, but at the time
2368 the cookie tag is created, the request line has already been parsed.
2372 While this is a limitation you should be aware of, this kind of
2373 indirection is seldom needed anyway and even the example doesn't
2374 make too much sense.
2379 <!-- ~~~~~ New section ~~~~~ -->
2380 <sect3 id="negative-tag-patterns"><title>The Negative Request Tag Patterns</title>
2383 To match requests that do not have a certain request tag, specify a negative tag pattern
2384 by prefixing the tag pattern line with either <quote>NO-REQUEST-TAG:</quote>
2385 or <quote>NO-RESPONSE-TAG:</quote> instead of <quote>TAG:</quote>.
2389 Negative request tag patterns created with <quote>NO-REQUEST-TAG:</quote> are checked
2390 after all client headers are scanned, the ones created with <quote>NO-RESPONSE-TAG:</quote>
2391 are checked after all server headers are scanned. In both cases all the created
2392 tags are considered.
2396 <!-- ~~~~~ New section ~~~~~ -->
2397 <sect3 id="client-tag-pattern"><title>The Client Tag Pattern</title>
2399 <!-- XXX: This section contains duplicates content from the
2400 client-specific-tag documentation. -->
2404 This is an experimental feature. The syntax is likely to change in future versions.
2409 Client tag patterns are not set based on HTTP headers but based on
2410 the client's IP address. Users can enable them themselves, but the
2411 Privoxy admin controls which tags are available and what their effect
2416 After a client-specific tag has been defined with the
2417 <link linkend="client-specific-tag">client-specific-tag</link>,
2418 directive, action sections can be activated based on the tag by using a
2419 CLIENT-TAG pattern. The CLIENT-TAG pattern is evaluated at the same priority
2420 as URL patterns, as a result the last matching pattern wins. Tags that
2421 are created based on client or server headers are evaluated later on
2422 and can overrule CLIENT-TAG and URL patterns!
2425 The tag is set for all requests that come from clients that requested
2426 it to be set. Note that "clients" are differentiated by IP address,
2427 if the IP address changes the tag has to be requested again.
2430 Clients can request tags to be set by using the CGI interface <ulink
2431 url="http://config.privoxy.org/client-tags">http://config.privoxy.org/client-tags</ulink>.
2440 # If the admin defined the client-specific-tag circumvent-blocks,
2441 # and the request comes from a client that previously requested
2442 # the tag to be set, overrule all previous +block actions that
2443 # are enabled based on URL to CLIENT-TAG patterns.
2445 CLIENT-TAG:^circumvent-blocks$
2447 # This section is not overruled because it's located after
2449 {+block{Nobody is supposed to request this.}}
2450 example.org/blocked-example-page</screen>
2457 <!-- ~ End section ~ -->
2460 <!-- ~~~~~ New section ~~~~~ -->
2462 <sect2 id="actions">
2463 <title>Actions</title>
2465 All actions are disabled by default, until they are explicitly enabled
2466 somewhere in an actions file. Actions are turned on if preceded with a
2467 <quote>+</quote>, and turned off if preceded with a <quote>-</quote>. So a
2468 <literal>+action</literal> means <quote>do that action</quote>, e.g.
2469 <literal>+block</literal> means <quote>please block URLs that match the
2470 following patterns</quote>, and <literal>-block</literal> means <quote>don't
2471 block URLs that match the following patterns, even if <literal>+block</literal>
2472 previously applied.</quote>
2477 Again, actions are invoked by placing them on a line, enclosed in curly braces and
2478 separated by whitespace, like in
2479 <literal>{+some-action -some-other-action{some-parameter}}</literal>,
2480 followed by a list of URL patterns, one per line, to which they apply.
2481 Together, the actions line and the following pattern lines make up a section
2482 of the actions file.
2486 Actions fall into three categories:
2493 Boolean, i.e the action can only be <quote>enabled</quote> or
2494 <quote>disabled</quote>. Syntax:
2498 +<replaceable class="function">name</replaceable> # enable action <replaceable class="parameter">name</replaceable>
2499 -<replaceable class="function">name</replaceable> # disable action <replaceable class="parameter">name</replaceable></screen>
2502 Example: <literal>+handle-as-image</literal>
2509 Parameterized, where some value is required in order to enable this type of action.
2514 +<replaceable class="function">name</replaceable>{<replaceable class="parameter">param</replaceable>} # enable action and set parameter to <replaceable class="parameter">param</replaceable>,
2515 # overwriting parameter from previous match if necessary
2516 -<replaceable class="function">name</replaceable> # disable action. The parameter can be omitted</screen>
2519 Note that if the URL matches multiple positive forms of a parameterized action,
2520 the last match wins, i.e. the params from earlier matches are simply ignored.
2523 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>
2529 Multi-value. These look exactly like parameterized actions,
2530 but they behave differently: If the action applies multiple times to the
2531 same URL, but with different parameters, <emphasis>all</emphasis> the parameters
2532 from <emphasis>all</emphasis> matches are remembered. This is used for actions
2533 that can be executed for the same request repeatedly, like adding multiple
2534 headers, or filtering through multiple filters. Syntax:
2538 +<replaceable class="function">name</replaceable>{<replaceable class="parameter">param</replaceable>} # enable action and add <replaceable class="parameter">param</replaceable> to the list of parameters
2539 -<replaceable class="function">name</replaceable>{<replaceable class="parameter">param</replaceable>} # remove the parameter <replaceable class="parameter">param</replaceable> from the list of parameters
2540 # If it was the last one left, disable the action.
2541 <replaceable class="parameter">-name</replaceable> # disable this action completely and remove all parameters from the list</screen>
2544 Examples: <literal>+add-header{X-Fun-Header: Some text}</literal> and
2545 <literal>+filter{html-annoyances}</literal>
2553 If nothing is specified in any actions file, no <quote>actions</quote> are
2554 taken. So in this case <application>Privoxy</application> would just be a
2555 normal, non-blocking, non-filtering proxy. You must specifically enable the
2556 privacy and blocking features you need (although the provided default actions
2557 files will give a good starting point).
2561 Later defined action sections always over-ride earlier ones of the same type.
2562 So exceptions to any rules you make, should come in the latter part of the file (or
2563 in a file that is processed later when using multiple actions files such
2564 as <filename>user.action</filename>). For multi-valued actions, the actions
2565 are applied in the order they are specified. Actions files are processed in
2566 the order they are defined in <filename>config</filename> (the default
2567 installation has three actions files). It also quite possible for any given
2568 URL to match more than one <quote>pattern</quote> (because of wildcards and
2569 regular expressions), and thus to trigger more than one set of actions! Last
2573 <!-- start actions listing -->
2575 The list of valid <application>Privoxy</application> actions are:
2579 <!-- ********************************************************** -->
2580 <!-- Please note the below defined actions use id's that are -->
2581 <!-- probably linked from other places, so please don't change. -->
2583 <!-- ********************************************************** -->
2586 <!-- ~~~~~ New section ~~~~~ -->
2588 <sect3 renderas="sect4" id="add-header">
2589 <title>add-header</title>
2593 <term>Typical use:</term>
2595 <para>Confuse log analysis, custom applications</para>
2600 <term>Effect:</term>
2603 Sends a user defined HTTP header to the web server.
2610 <!-- boolean, parameterized, Multi-value -->
2612 <para>Multi-value.</para>
2617 <term>Parameter:</term>
2620 Any string value is possible. Validity of the defined HTTP headers is not checked.
2621 It is recommended that you use the <quote><literal>X-</literal></quote> prefix
2631 This action may be specified multiple times, in order to define multiple
2632 headers. This is rarely needed for the typical user. If you don't know what
2633 <quote>HTTP headers</quote> are, you definitely don't need to worry about this
2637 Headers added by this action are not modified by other actions.
2643 <term>Example usage:</term>
2646 <screen># Add a DNT ("Do not track") header to all requests,
2647 # event to those that already have one.
2649 # This is just an example, not a recommendation.
2651 # There is no reason to believe that user-tracking websites care
2652 # about the DNT header and depending on the User-Agent, adding the
2653 # header may make user-tracking easier.
2654 {+add-header{DNT: 1}}
2663 <!-- ~~~~~ New section ~~~~~ -->
2664 <sect3 renderas="sect4" id="block">
2665 <title>block</title>
2669 <term>Typical use:</term>
2671 <para>Block ads or other unwanted content</para>
2676 <term>Effect:</term>
2679 Requests for URLs to which this action applies are blocked, i.e. the
2680 requests are trapped by &my-app; and the requested URL is never retrieved,
2681 but is answered locally with a substitute page or image, as determined by
2683 linkend="handle-as-image">handle-as-image</link></literal>,
2685 linkend="set-image-blocker">set-image-blocker</link></literal>, and
2687 linkend="handle-as-empty-document">handle-as-empty-document</link></literal> actions.
2695 <!-- boolean, parameterized, Multi-value -->
2697 <para>Parameterized.</para>
2702 <term>Parameter:</term>
2704 <para>A block reason that should be given to the user.</para>
2712 <application>Privoxy</application> sends a special <quote>BLOCKED</quote> page
2713 for requests to blocked pages. This page contains the block reason given as
2714 parameter, a link to find out why the block action applies, and a click-through
2715 to the blocked content (the latter only if the force feature is available and
2719 A very important exception occurs if <emphasis>both</emphasis>
2720 <literal>block</literal> and <literal><link linkend="handle-as-image">handle-as-image</link></literal>,
2721 apply to the same request: it will then be replaced by an image. If
2722 <literal><link linkend="set-image-blocker">set-image-blocker</link></literal>
2723 (see below) also applies, the type of image will be determined by its parameter,
2724 if not, the standard checkerboard pattern is sent.
2727 It is important to understand this process, in order
2728 to understand how <application>Privoxy</application> deals with
2729 ads and other unwanted content. Blocking is a core feature, and one
2730 upon which various other features depend.
2733 The <literal><link linkend="filter">filter</link></literal>
2734 action can perform a very similar task, by <quote>blocking</quote>
2735 banner images and other content through rewriting the relevant URLs in the
2736 document's HTML source, so they don't get requested in the first place.
2737 Note that this is a totally different technique, and it's easy to confuse the two.
2743 <term>Example usage (section):</term>
2746 <screen>{+block{No nasty stuff for you.}}
2747 # Block and replace with "blocked" page
2748 .nasty-stuff.example.com
2750 {+block{Doubleclick banners.} +handle-as-image}
2751 # Block and replace with image
2755 {+block{Layered ads.} +handle-as-empty-document}
2756 # Block and then ignore
2757 adserver.example.net/.*\.js$</screen>
2767 <!-- ~~~~~ New section ~~~~~ -->
2768 <sect3 renderas="sect4" id="change-x-forwarded-for">
2769 <title>change-x-forwarded-for</title>
2773 <term>Typical use:</term>
2775 <para>Improve privacy by not forwarding the source of the request in the HTTP headers.</para>
2780 <term>Effect:</term>
2783 Deletes the <quote>X-Forwarded-For:</quote> HTTP header from the client request,
2791 <!-- Boolean, Parameterized, Multi-value -->
2793 <para>Parameterized.</para>
2798 <term>Parameter:</term>
2802 <para><quote>block</quote> to delete the header.</para>
2806 <quote>add</quote> to create the header (or append
2807 the client's IP address to an already existing one).
2818 It is safe and recommended to use <literal>block</literal>.
2821 Forwarding the source address of the request may make
2822 sense in some multi-user setups but is also a privacy risk.
2827 <term>Example usage:</term>
2830 <screen>+change-x-forwarded-for{block}</screen>
2837 <!-- ~~~~~ New section ~~~~~ -->
2838 <sect3 renderas="sect4" id="client-header-filter">
2839 <title>client-header-filter</title>
2843 <term>Typical use:</term>
2846 Rewrite or remove single client headers.
2852 <term>Effect:</term>
2855 All client headers to which this action applies are filtered on-the-fly through
2856 the specified regular expression based substitutions.
2863 <!-- boolean, parameterized, Multi-value -->
2865 <para>Multi-value.</para>
2870 <term>Parameter:</term>
2873 The name of a client-header filter, as defined in one of the
2874 <link linkend="filter-file">filter files</link>.
2883 Client-header filters are applied to each header on its own, not to
2884 all at once. This makes it easier to diagnose problems, but on the downside
2885 you can't write filters that only change header x if header y's value is z.
2886 You can do that by using tags though.
2889 Client-header filters are executed after the other header actions have finished
2890 and use their output as input.
2893 If the request URI gets changed, &my-app; will detect that and use the new
2894 one. This can be used to rewrite the request destination behind the client's
2895 back, for example to specify a Tor exit relay for certain requests.
2898 Please refer to the <link linkend="filter-file">filter file chapter</link>
2899 to learn which client-header filters are available by default, and how to
2907 <term>Example usage (section):</term>
2911 # Hide Tor exit notation in Host and Referer Headers
2912 {+client-header-filter{hide-tor-exit-notation}}
2923 <!-- ~~~~~ New section ~~~~~ -->
2924 <sect3 renderas="sect4" id="client-header-tagger">
2925 <title>client-header-tagger</title>
2929 <term>Typical use:</term>
2932 Block requests based on their headers.
2938 <term>Effect:</term>
2941 Client headers to which this action applies are filtered on-the-fly through
2942 the specified regular expression based substitutions, the result is used as
2950 <!-- boolean, parameterized, Multi-value -->
2952 <para>Multi-value.</para>
2957 <term>Parameter:</term>
2960 The name of a client-header tagger, as defined in one of the
2961 <link linkend="filter-file">filter files</link>.
2970 Client-header taggers are applied to each header on its own,
2971 and as the header isn't modified, each tagger <quote>sees</quote>
2975 Client-header taggers are the first actions that are executed
2976 and their tags can be used to control every other action.
2982 <term>Example usage (section):</term>
2986 # Tag every request with the User-Agent header
2987 {+client-header-tagger{user-agent}}
2990 # Tagging itself doesn't change the action
2991 # settings, sections with TAG patterns do:
2993 # If it's a download agent, use a different forwarding proxy,
2994 # show the real User-Agent and make sure resume works.
2995 {+forward-override{forward-socks5 10.0.0.2:2222 .} \
2996 -hide-if-modified-since \
2997 -overwrite-last-modified \
3002 TAG:^User-Agent: NetBSD-ftp/
3003 TAG:^User-Agent: Novell ZYPP Installer
3004 TAG:^User-Agent: RPM APT-HTTP/
3005 TAG:^User-Agent: fetch libfetch/
3006 TAG:^User-Agent: Ubuntu APT-HTTP/
3007 TAG:^User-Agent: MPlayer/
3012 # Tag all requests with the Range header set
3013 {+client-header-tagger{range-requests}}
3016 # Disable filtering for the tagged requests.
3018 # With filtering enabled Privoxy would remove the Range headers
3019 # to be able to filter the whole response. The downside is that
3020 # it prevents clients from resuming downloads or skipping over
3021 # parts of multimedia files.
3022 {-filter -deanimate-gifs}
3028 # Tag all requests with the client IP address
3030 # (Technically the client IP address isn't included in the
3031 # client headers but client-header taggers can set it anyway.
3032 # For details see the tagger in default.filter)
3033 {+client-header-tagger{client-ip-address}}
3036 # Change forwarding settings for requests coming from address 10.0.0.1
3037 {+forward-override{forward-socks5 127.0.1.2:2222 .}}
3038 TAG:^IP-ADDRESS: 10\.0\.0\.1$
3048 <!-- ~~~~~ New section ~~~~~ -->
3049 <sect3 renderas="sect4" id="content-type-overwrite">
3050 <title>content-type-overwrite</title>
3054 <term>Typical use:</term>
3056 <para>Stop useless download menus from popping up, or change the browser's rendering mode</para>
3061 <term>Effect:</term>
3064 Replaces the <quote>Content-Type:</quote> HTTP server header.
3071 <!-- Boolean, Parameterized, Multi-value -->
3073 <para>Parameterized.</para>
3078 <term>Parameter:</term>
3090 The <quote>Content-Type:</quote> HTTP server header is used by the
3091 browser to decide what to do with the document. The value of this
3092 header can cause the browser to open a download menu instead of
3093 displaying the document by itself, even if the document's format is
3094 supported by the browser.
3097 The declared content type can also affect which rendering mode
3098 the browser chooses. If XHTML is delivered as <quote>text/html</quote>,
3099 many browsers treat it as yet another broken HTML document.
3100 If it is send as <quote>application/xml</quote>, browsers with
3101 XHTML support will only display it, if the syntax is correct.
3104 If you see a web site that proudly uses XHTML buttons, but sets
3105 <quote>Content-Type: text/html</quote>, you can use &my-app;
3106 to overwrite it with <quote>application/xml</quote> and validate
3107 the web master's claim inside your XHTML-supporting browser.
3108 If the syntax is incorrect, the browser will complain loudly.
3111 You can also go the opposite direction: if your browser prints
3112 error messages instead of rendering a document falsely declared
3113 as XHTML, you can overwrite the content type with
3114 <quote>text/html</quote> and have it rendered as broken HTML document.
3117 By default <literal>content-type-overwrite</literal> only replaces
3118 <quote>Content-Type:</quote> headers that look like some kind of text.
3119 If you want to overwrite it unconditionally, you have to combine it with
3120 <literal><link linkend="force-text-mode">force-text-mode</link></literal>.
3121 This limitation exists for a reason, think twice before circumventing it.
3124 Most of the time it's easier to replace this action with a custom
3125 <literal><link linkend="server-header-filter">server-header filter</link></literal>.
3126 It allows you to activate it for every document of a certain site and it will still
3127 only replace the content types you aimed at.
3130 Of course you can apply <literal>content-type-overwrite</literal>
3131 to a whole site and then make URL based exceptions, but it's a lot
3132 more work to get the same precision.
3138 <term>Example usage (sections):</term>
3141 <screen># Check if www.example.net/ really uses valid XHTML
3142 { +content-type-overwrite{application/xml} }
3145 # but leave the content type unmodified if the URL looks like a style sheet
3146 {-content-type-overwrite}
3147 www.example.net/.*\.css$
3148 www.example.net/.*style
3157 <!-- ~~~~~ New section ~~~~~ -->
3158 <sect3 renderas="sect4" id="crunch-client-header">
3162 <title>crunch-client-header</title>
3166 <term>Typical use:</term>
3168 <para>Remove a client header <application>Privoxy</application> has no dedicated action for.</para>
3173 <term>Effect:</term>
3176 Deletes every header sent by the client that contains the string the user supplied as parameter.
3183 <!-- Boolean, Parameterized, Multi-value -->
3185 <para>Parameterized.</para>
3190 <term>Parameter:</term>
3202 This action allows you to block client headers for which no dedicated
3203 <application>Privoxy</application> action exists.
3204 <application>Privoxy</application> will remove every client header that
3205 contains the string you supplied as parameter.
3208 Regular expressions are <emphasis>not supported</emphasis> and you can't
3209 use this action to block different headers in the same request, unless
3210 they contain the same string.
3213 <literal>crunch-client-header</literal> is only meant for quick tests.
3214 If you have to block several different headers, or only want to modify
3215 parts of them, you should use a
3216 <literal><link linkend="client-header-filter">client-header filter</link></literal>.
3220 Don't block any header without understanding the consequences.
3227 <term>Example usage (section):</term>
3230 <screen># Block the non-existent "Privacy-Violation:" client header
3231 { +crunch-client-header{Privacy-Violation:} }
3241 <!-- ~~~~~ New section ~~~~~ -->
3242 <sect3 renderas="sect4" id="crunch-if-none-match">
3243 <title>crunch-if-none-match</title>
3249 <term>Typical use:</term>
3251 <para>Prevent yet another way to track the user's steps between sessions.</para>
3256 <term>Effect:</term>
3259 Deletes the <quote>If-None-Match:</quote> HTTP client header.
3266 <!-- Boolean, Parameterized, Multi-value -->
3268 <para>Boolean.</para>
3273 <term>Parameter:</term>
3285 Removing the <quote>If-None-Match:</quote> HTTP client header
3286 is useful for filter testing, where you want to force a real
3287 reload instead of getting status code <quote>304</quote> which
3288 would cause the browser to use a cached copy of the page.
3291 It is also useful to make sure the header isn't used as a cookie
3292 replacement (unlikely but possible).
3295 Blocking the <quote>If-None-Match:</quote> header shouldn't cause any
3296 caching problems, as long as the <quote>If-Modified-Since:</quote> header
3297 isn't blocked or missing as well.
3300 It is recommended to use this action together with
3301 <literal><link linkend="hide-if-modified-since">hide-if-modified-since</link></literal>
3303 <literal><link linkend="overwrite-last-modified">overwrite-last-modified</link></literal>.
3309 <term>Example usage (section):</term>
3312 <screen># Let the browser revalidate cached documents but don't
3313 # allow the server to use the revalidation headers for user tracking.
3314 {+hide-if-modified-since{-60} \
3315 +overwrite-last-modified{randomize} \
3316 +crunch-if-none-match}
3325 <!-- ~~~~~ New section ~~~~~ -->
3326 <sect3 renderas="sect4" id="crunch-incoming-cookies">
3327 <title>crunch-incoming-cookies</title>
3331 <term>Typical use:</term>
3334 Prevent the web server from setting HTTP cookies on your system
3340 <term>Effect:</term>
3343 Deletes any <quote>Set-Cookie:</quote> HTTP headers from server replies.
3350 <!-- Boolean, Parameterized, Multi-value -->
3352 <para>Boolean.</para>
3357 <term>Parameter:</term>
3369 This action is only concerned with <emphasis>incoming</emphasis> HTTP cookies. For
3370 <emphasis>outgoing</emphasis> HTTP cookies, use
3371 <literal><link linkend="crunch-outgoing-cookies">crunch-outgoing-cookies</link></literal>.
3372 Use <emphasis>both</emphasis> to disable HTTP cookies completely.
3375 It makes <emphasis>no sense at all</emphasis> to use this action in conjunction
3376 with the <literal><link linkend="session-cookies-only">session-cookies-only</link></literal> action,
3377 since it would prevent the session cookies from being set. See also
3378 <literal><link linkend="filter-content-cookies">filter-content-cookies</link></literal>.
3384 <term>Example usage:</term>
3387 <screen>+crunch-incoming-cookies</screen>
3395 <!-- ~~~~~ New section ~~~~~ -->
3396 <sect3 renderas="sect4" id="crunch-server-header">
3397 <title>crunch-server-header</title>
3403 <term>Typical use:</term>
3405 <para>Remove a server header <application>Privoxy</application> has no dedicated action for.</para>
3410 <term>Effect:</term>
3413 Deletes every header sent by the server that contains the string the user supplied as parameter.
3420 <!-- Boolean, Parameterized, Multi-value -->
3422 <para>Parameterized.</para>
3427 <term>Parameter:</term>
3439 This action allows you to block server headers for which no dedicated
3440 <application>Privoxy</application> action exists. <application>Privoxy</application>
3441 will remove every server header that contains the string you supplied as parameter.
3444 Regular expressions are <emphasis>not supported</emphasis> and you can't
3445 use this action to block different headers in the same request, unless
3446 they contain the same string.
3449 <literal>crunch-server-header</literal> is only meant for quick tests.
3450 If you have to block several different headers, or only want to modify
3451 parts of them, you should use a custom
3452 <literal><link linkend="server-header-filter">server-header filter</link></literal>.
3456 Don't block any header without understanding the consequences.
3463 <term>Example usage (section):</term>
3466 <screen># Crunch server headers that try to prevent caching
3467 { +crunch-server-header{no-cache} }
3476 <!-- ~~~~~ New section ~~~~~ -->
3477 <sect3 renderas="sect4" id="crunch-outgoing-cookies">
3478 <title>crunch-outgoing-cookies</title>
3482 <term>Typical use:</term>
3485 Prevent the web server from reading any HTTP cookies from your system
3491 <term>Effect:</term>
3494 Deletes any <quote>Cookie:</quote> HTTP headers from client requests.
3501 <!-- Boolean, Parameterized, Multi-value -->
3503 <para>Boolean.</para>
3508 <term>Parameter:</term>
3520 This action is only concerned with <emphasis>outgoing</emphasis> HTTP cookies. For
3521 <emphasis>incoming</emphasis> HTTP cookies, use
3522 <literal><link linkend="crunch-incoming-cookies">crunch-incoming-cookies</link></literal>.
3523 Use <emphasis>both</emphasis> to disable HTTP cookies completely.
3526 It makes <emphasis>no sense at all</emphasis> to use this action in conjunction
3527 with the <literal><link linkend="session-cookies-only">session-cookies-only</link></literal> action,
3528 since it would prevent the session cookies from being read.
3534 <term>Example usage:</term>
3537 <screen>+crunch-outgoing-cookies</screen>
3546 <!-- ~~~~~ New section ~~~~~ -->
3547 <sect3 renderas="sect4" id="deanimate-gifs">
3548 <title>deanimate-gifs</title>
3552 <term>Typical use:</term>
3554 <para>Stop those annoying, distracting animated GIF images.</para>
3559 <term>Effect:</term>
3562 De-animate GIF animations, i.e. reduce them to their first or last image.
3569 <!-- boolean, parameterized, Multi-value -->
3571 <para>Parameterized.</para>
3576 <term>Parameter:</term>
3579 <quote>last</quote> or <quote>first</quote>
3588 This will also shrink the images considerably (in bytes, not pixels!). If
3589 the option <quote>first</quote> is given, the first frame of the animation
3590 is used as the replacement. If <quote>last</quote> is given, the last
3591 frame of the animation is used instead, which probably makes more sense for
3592 most banner animations, but also has the risk of not showing the entire
3593 last frame (if it is only a delta to an earlier frame).
3596 You can safely use this action with patterns that will also match non-GIF
3597 objects, because no attempt will be made at anything that doesn't look like
3604 <term>Example usage:</term>
3607 <screen>+deanimate-gifs{last}</screen>
3614 <!-- ~~~~~ New section ~~~~~ -->
3615 <sect3 renderas="sect4" id="downgrade-http-version">
3616 <title>downgrade-http-version</title>
3620 <term>Typical use:</term>
3622 <para>Work around (very rare) problems with HTTP/1.1</para>
3627 <term>Effect:</term>
3630 Downgrades HTTP/1.1 client requests and server replies to HTTP/1.0.
3637 <!-- boolean, parameterized, Multi-value -->
3639 <para>Boolean.</para>
3644 <term>Parameter:</term>
3656 This is a left-over from the time when <application>Privoxy</application>
3657 didn't support important HTTP/1.1 features well. It is left here for the
3658 unlikely case that you experience HTTP/1.1-related problems with some server
3662 Note that enabling this action is only a workaround. It should not
3663 be enabled for sites that work without it. While it shouldn't break
3664 any pages, it has an (usually negative) performance impact.
3667 If you come across a site where enabling this action helps, please report it,
3668 so the cause of the problem can be analyzed. If the problem turns out to be
3669 caused by a bug in <application>Privoxy</application> it should be
3670 fixed so the following release works without the work around.
3676 <term>Example usage (section):</term>
3679 <screen>{+downgrade-http-version}
3680 problem-host.example.com</screen>
3688 <!-- ~~~~~ New section ~~~~~ -->
3689 <sect3 renderas="sect4" id="external-filter">
3690 <title>external-filter</title>
3694 <term>Typical use:</term>
3696 <para>Modify content using a programming language of your choice.</para>
3701 <term>Effect:</term>
3704 All instances of text-based type, most notably HTML and JavaScript, to which
3705 this action applies, can be filtered on-the-fly through the specified external
3707 By default plain text documents are exempted from filtering, because web
3708 servers often use the <literal>text/plain</literal> MIME type for all files
3709 whose type they don't know.)
3716 <!-- boolean, parameterized, Multi-value -->
3718 <para>Multi-value.</para>
3723 <term>Parameter:</term>
3726 The name of an external content filter, as defined in the
3727 <link linkend="filter-file">filter file</link>.
3728 External filters can be defined in one or more files as defined by the
3729 <literal><link linkend="filterfile">filterfile</link></literal>
3730 option in the <link linkend="config">config file</link>.
3733 When used in its negative form,
3734 and without parameters, <emphasis>all</emphasis> filtering with external
3735 filters is completely disabled.
3744 External filters are scripts or programs that can modify the content in
3745 case common <literal><link linkend="filter">filters</link></literal>
3746 aren't powerful enough. With the exception that this action doesn't
3747 use pcrs-based filters, the notes in the
3748 <literal><link linkend="filter">filter</link></literal> section apply.
3752 Currently external filters are executed with &my-app;'s privileges.
3753 Only use external filters you understand and trust.
3757 This feature is experimental, the <literal><link
3758 linkend="external-filter-syntax">syntax</link></literal>
3759 may change in the future.
3766 <term>Example usage:</term>
3769 <screen>+external-filter{fancy-filter}</screen>
3776 <!-- ~~~~~ New section ~~~~~ -->
3777 <sect3 renderas="sect4" id="fast-redirects">
3778 <title>fast-redirects</title>
3782 <term>Typical use:</term>
3784 <para>Fool some click-tracking scripts and speed up indirect links.</para>
3789 <term>Effect:</term>
3792 Detects redirection URLs and redirects the browser without contacting
3793 the redirection server first.
3800 <!-- boolean, parameterized, Multi-value -->
3802 <para>Parameterized.</para>
3807 <term>Parameter:</term>
3812 <quote>simple-check</quote> to just search for the string <quote>http://</quote>
3813 to detect redirection URLs.
3818 <quote>check-decoded-url</quote> to decode URLs (if necessary) before searching
3819 for redirection URLs.
3830 Many sites, like yahoo.com, don't just link to other sites. Instead, they
3831 will link to some script on their own servers, giving the destination as a
3832 parameter, which will then redirect you to the final target. URLs
3833 resulting from this scheme typically look like:
3834 <quote>http://www.example.org/click-tracker.cgi?target=http%3a//www.example.net/</quote>.
3837 Sometimes, there are even multiple consecutive redirects encoded in the
3838 URL. These redirections via scripts make your web browsing more traceable,
3839 since the server from which you follow such a link can see where you go
3840 to. Apart from that, valuable bandwidth and time is wasted, while your
3841 browser asks the server for one redirect after the other. Plus, it feeds
3845 This feature is currently not very smart and is scheduled for improvement.
3846 If it is enabled by default, you will have to create some exceptions to
3847 this action. It can lead to failures in several ways:
3850 Not every URLs with other URLs as parameters is evil.
3851 Some sites offer a real service that requires this information to work.
3852 For example a validation service needs to know, which document to validate.
3853 <literal>fast-redirects</literal> assumes that every URL parameter that
3854 looks like another URL is a redirection target, and will always redirect to
3855 the last one. Most of the time the assumption is correct, but if it isn't,
3856 the user gets redirected anyway.
3859 Another failure occurs if the URL contains other parameters after the URL parameter.
3861 <quote>http://www.example.org/?redirect=http%3a//www.example.net/&foo=bar</quote>.
3862 contains the redirection URL <quote>http://www.example.net/</quote>,
3863 followed by another parameter. <literal>fast-redirects</literal> doesn't know that
3864 and will cause a redirect to <quote>http://www.example.net/&foo=bar</quote>.
3865 Depending on the target server configuration, the parameter will be silently ignored
3866 or lead to a <quote>page not found</quote> error. You can prevent this problem by
3867 first using the <literal><link linkend="redirect">redirect</link></literal> action
3868 to remove the last part of the URL, but it requires a little effort.
3871 To detect a redirection URL, <literal>fast-redirects</literal> only
3872 looks for the string <quote>http://</quote>, either in plain text
3873 (invalid but often used) or encoded as <quote>http%3a//</quote>.
3874 Some sites use their own URL encoding scheme, encrypt the address
3875 of the target server or replace it with a database id. In theses cases
3876 <literal>fast-redirects</literal> is fooled and the request reaches the
3877 redirection server where it probably gets logged.
3883 <term>Example usage:</term>
3887 { +fast-redirects{simple-check} }
3890 { +fast-redirects{check-decoded-url} }
3891 another.example.com/testing</screen>
3900 <!-- ~~~~~ New section ~~~~~ -->
3901 <sect3 renderas="sect4" id="filter">
3902 <title>filter</title>
3906 <term>Typical use:</term>
3908 <para>Get rid of HTML and JavaScript annoyances, banner advertisements (by size),
3909 do fun text replacements, add personalized effects, etc.</para>
3914 <term>Effect:</term>
3917 All instances of text-based type, most notably HTML and JavaScript, to which
3918 this action applies, can be filtered on-the-fly through the specified regular
3919 expression based substitutions. (Note: as of version 3.0.3 plain text documents
3920 are exempted from filtering, because web servers often use the
3921 <literal>text/plain</literal> MIME type for all files whose type they don't know.)
3928 <!-- boolean, parameterized, Multi-value -->
3930 <para>Multi-value.</para>
3935 <term>Parameter:</term>
3938 The name of a content filter, as defined in the <link linkend="filter-file">filter file</link>.
3939 Filters can be defined in one or more files as defined by the
3940 <literal><link linkend="filterfile">filterfile</link></literal>
3941 option in the <link linkend="config">config file</link>.
3942 <filename>default.filter</filename> is the collection of filters
3943 supplied by the developers. Locally defined filters should go
3944 in their own file, such as <filename>user.filter</filename>.
3947 When used in its negative form,
3948 and without parameters, <emphasis>all</emphasis> filtering is completely disabled.
3957 For your convenience, there are a number of pre-defined filters available
3958 in the distribution filter file that you can use. See the examples below for
3962 Filtering requires buffering the page content, which may appear to
3963 slow down page rendering since nothing is displayed until all content has
3964 passed the filters. (The total time until the page is completely rendered
3965 doesn't change much, but it may be perceived as slower since the page is
3966 not incrementally displayed.)
3967 This effect will be more noticeable on slower connections.
3970 <quote>Rolling your own</quote>
3971 filters requires a knowledge of
3972 <ulink url="http://en.wikipedia.org/wiki/Regular_expressions"><quote>Regular
3973 Expressions</quote></ulink> and
3974 <ulink url="http://en.wikipedia.org/wiki/Html"><quote>HTML</quote></ulink>.
3975 This is very powerful feature, and potentially very intrusive.
3976 Filters should be used with caution, and where an equivalent
3977 <quote>action</quote> is not available.
3980 The amount of data that can be filtered is limited to the
3981 <literal><link linkend="buffer-limit">buffer-limit</link></literal>
3982 option in the main <link linkend="config">config file</link>. The
3983 default is 4096 KB (4 Megs). Once this limit is exceeded, the buffered
3984 data, and all pending data, is passed through unfiltered.
3987 Inappropriate MIME types, such as zipped files, are not filtered at all.
3988 (Again, only text-based types except plain text). Encrypted SSL data
3989 (from HTTPS servers) cannot be filtered either, since this would violate
3990 the integrity of the secure transaction. In some situations it might
3991 be necessary to protect certain text, like source code, from filtering
3992 by defining appropriate <literal>-filter</literal> exceptions.
3995 Compressed content can't be filtered either, but if &my-app;
3996 is compiled with zlib support and a supported compression algorithm
3997 is used (gzip or deflate), &my-app; can first decompress the content
4001 If you use a &my-app; version without zlib support, but want filtering to work on
4002 as much documents as possible, even those that would normally be sent compressed,
4003 you must use the <literal><link linkend="prevent-compression">prevent-compression</link></literal>
4004 action in conjunction with <literal>filter</literal>.
4007 Content filtering can achieve some of the same effects as the
4008 <literal><link linkend="block">block</link></literal>
4009 action, i.e. it can be used to block ads and banners. But the mechanism
4010 works quite differently. One effective use, is to block ad banners
4011 based on their size (see below), since many of these seem to be somewhat
4015 <link linkend="contact">Feedback</link> with suggestions for new or
4016 improved filters is particularly welcome!
4019 The below list has only the names and a one-line description of each
4020 predefined filter. There are <link linkend="predefined-filters">more
4021 verbose explanations</link> of what these filters do in the <link
4022 linkend="filter-file">filter file chapter</link>.
4028 <term>Example usage (with filters from the distribution <filename>default.filter</filename> file).
4029 See <link linkend="PREDEFINED-FILTERS">the Predefined Filters section</link> for
4030 more explanation on each:</term>
4033 <anchor id="filter-js-annoyances">
4034 <screen>+filter{js-annoyances} # Get rid of particularly annoying JavaScript abuse.</screen>
4037 <anchor id="filter-js-events">
4038 <screen>+filter{js-events} # Kill JavaScript event bindings and timers (Radically destructive! Only for extra nasty sites).</screen>
4041 <anchor id="filter-html-annoyances">
4042 <screen>+filter{html-annoyances} # Get rid of particularly annoying HTML abuse.</screen>
4045 <anchor id="filter-content-cookies">
4046 <screen>+filter{content-cookies} # Kill cookies that come in the HTML or JS content.</screen>
4049 <anchor id="filter-refresh-tags">
4050 <screen>+filter{refresh-tags} # Kill automatic refresh tags if refresh time is larger than 9 seconds.</screen>
4053 <anchor id="filter-unsolicited-popups">
4054 <screen>+filter{unsolicited-popups} # Disable only unsolicited pop-up windows.</screen>
4057 <anchor id="filter-all-popups">
4058 <screen>+filter{all-popups} # Kill all popups in JavaScript and HTML.</screen>
4061 <anchor id="filter-img-reorder">
4062 <screen>+filter{img-reorder} # Reorder attributes in <img> tags to make the banners-by-* filters more effective.</screen>
4065 <anchor id="filter-banners-by-size">
4066 <screen>+filter{banners-by-size} # Kill banners by size.</screen>
4069 <anchor id="filter-banners-by-link">
4070 <screen>+filter{banners-by-link} # Kill banners by their links to known clicktrackers.</screen>
4073 <anchor id="filter-webbugs">
4074 <screen>+filter{webbugs} # Squish WebBugs (1x1 invisible GIFs used for user tracking).</screen>
4077 <anchor id="filter-tiny-textforms">
4078 <screen>+filter{tiny-textforms} # Extend those tiny textareas up to 40x80 and kill the hard wrap.</screen>
4081 <anchor id="filter-jumping-windows">
4082 <screen>+filter{jumping-windows} # Prevent windows from resizing and moving themselves.</screen>
4085 <anchor id="filter-frameset-borders">
4086 <screen>+filter{frameset-borders} # Give frames a border and make them resizable.</screen>
4089 <anchor id="filter-iframes">
4090 <screen>+filter{iframes} # Removes all detected iframes. Should only be enabled for individual sites.</screen>
4093 <anchor id="filter-demoronizer">
4094 <screen>+filter{demoronizer} # Fix MS's non-standard use of standard charsets.</screen>
4097 <anchor id="filter-shockwave-flash">
4098 <screen>+filter{shockwave-flash} # Kill embedded Shockwave Flash objects.</screen>
4101 <anchor id="filter-quicktime-kioskmode">
4102 <screen>+filter{quicktime-kioskmode} # Make Quicktime movies saveable.</screen>
4105 <anchor id="filter-fun">
4106 <screen>+filter{fun} # Text replacements for subversive browsing fun!</screen>
4109 <anchor id="filter-crude-parental">
4110 <screen>+filter{crude-parental} # Crude parental filtering. Note that this filter doesn't work reliably.</screen>
4113 <anchor id="filter-ie-exploits">
4114 <screen>+filter{ie-exploits} # Disable some known Internet Explorer bug exploits.</screen>
4117 <anchor id="filter-site-specifics">
4118 <screen>+filter{site-specifics} # Cure for site-specific problems. Don't apply generally!</screen>
4121 <anchor id="filter-no-ping">
4122 <screen>+filter{no-ping} # Removes non-standard ping attributes in <a> and <area> tags.</screen>
4125 <anchor id="filter-google">
4126 <screen>+filter{google} # CSS-based block for Google text ads. Also removes a width limitation and the toolbar advertisement.</screen>
4129 <anchor id="filter-yahoo">
4130 <screen>+filter{yahoo} # CSS-based block for Yahoo text ads. Also removes a width limitation.</screen>
4133 <anchor id="filter-msn">
4134 <screen>+filter{msn} # CSS-based block for MSN text ads. Also removes tracking URLs and a width limitation.</screen>
4137 <anchor id="filter-blogspot">
4138 <screen>+filter{blogspot} # Cleans up some Blogspot blogs. Read the fine print before using this.</screen>
4146 <!-- ~~~~~ New section ~~~~~ -->
4147 <sect3 renderas="sect4" id="force-text-mode">
4148 <title>force-text-mode</title>
4154 <term>Typical use:</term>
4156 <para>Force <application>Privoxy</application> to treat a document as if it was in some kind of <emphasis>text</emphasis> format. </para>
4161 <term>Effect:</term>
4164 Declares a document as text, even if the <quote>Content-Type:</quote> isn't detected as such.
4171 <!-- Boolean, Parameterized, Multi-value -->
4173 <para>Boolean.</para>
4178 <term>Parameter:</term>
4190 As explained <literal><link linkend="filter">above</link></literal>,
4191 <application>Privoxy</application> tries to only filter files that are
4192 in some kind of text format. The same restrictions apply to
4193 <literal><link linkend="content-type-overwrite">content-type-overwrite</link></literal>.
4194 <literal>force-text-mode</literal> declares a document as text,
4195 without looking at the <quote>Content-Type:</quote> first.
4199 Think twice before activating this action. Filtering binary data
4200 with regular expressions can cause file damage.
4207 <term>Example usage:</term>
4220 <!-- ~~~~~ New section ~~~~~ -->
4221 <sect3 renderas="sect4" id="forward-override">
4222 <title>forward-override</title>
4228 <term>Typical use:</term>
4230 <para>Change the forwarding settings based on User-Agent or request origin</para>
4235 <term>Effect:</term>
4238 Overrules the forward directives in the configuration file.
4245 <!-- Boolean, Parameterized, Multi-value -->
4247 <para>Parameterized.</para>
4252 <term>Parameter:</term>
4256 <para><quote>forward .</quote> to use a direct connection without any additional proxies.</para>
4260 <quote>forward 127.0.0.1:8123</quote> to use the HTTP proxy listening at 127.0.0.1 port 8123.
4265 <quote>forward-socks4a 127.0.0.1:9050 .</quote> to use the socks4a proxy listening at
4266 127.0.0.1 port 9050. Replace <quote>forward-socks4a</quote> with <quote>forward-socks4</quote>
4267 to use a socks4 connection (with local DNS resolution) instead, use <quote>forward-socks5</quote>
4268 for socks5 connections (with remote DNS resolution).
4273 <quote>forward-socks4a 127.0.0.1:9050 proxy.example.org:8000</quote> to use the socks4a proxy
4274 listening at 127.0.0.1 port 9050 to reach the HTTP proxy listening at proxy.example.org port 8000.
4275 Replace <quote>forward-socks4a</quote> with <quote>forward-socks4</quote> to use a socks4 connection
4276 (with local DNS resolution) instead, use <quote>forward-socks5</quote>
4277 for socks5 connections (with remote DNS resolution).
4282 <quote>forward-webserver 127.0.0.1:80</quote> to use the HTTP
4283 server listening at 127.0.0.1 port 80 without adjusting the
4287 This makes it more convenient to use Privoxy to make
4288 existing websites available as onion services as well.
4291 Many websites serve content with hardcoded URLs and
4292 can't be easily adjusted to change the domain based
4293 on the one used by the client.
4296 Putting Privoxy between Tor and the webserver (or an stunnel
4297 that forwards to the webserver) allows to rewrite headers and
4298 content to make client and server happy at the same time.
4301 Using Privoxy for webservers that are only reachable through
4302 onion addresses and whose location is supposed to be secret
4303 is not recommended and should not be necessary anyway.
4314 This action takes parameters similar to the
4315 <link linkend="forwarding">forward</link> directives in the configuration
4316 file, but without the URL pattern. It can be used as replacement, but normally it's only
4317 used in cases where matching based on the request URL isn't sufficient.
4321 Please read the description for the <link linkend="forwarding">forward</link> directives before
4322 using this action. Forwarding to the wrong people will reduce your privacy and increase the
4323 chances of man-in-the-middle attacks.
4326 If the ports are missing or invalid, default values will be used. This might change
4327 in the future and you shouldn't rely on it. Otherwise incorrect syntax causes Privoxy
4328 to exit. Due to design limitations, invalid parameter syntax isn't detected until the
4329 action is used the first time.
4332 Use the <ulink url="http://config.privoxy.org/show-url-info">show-url-info CGI page</ulink>
4333 to verify that your forward settings do what you thought the do.
4340 <term>Example usage:</term>
4344 # Use an ssh tunnel for requests previously tagged as
4345 # <quote>User-Agent: fetch libfetch/2.0</quote> and make sure
4346 # resuming downloads continues to work.
4348 # This way you can continue to use Tor for your normal browsing,
4349 # without overloading the Tor network with your FreeBSD ports updates
4350 # or downloads of bigger files like ISOs.
4352 # Note that HTTP headers are easy to fake and therefore their
4353 # values are as (un)trustworthy as your clients and users.
4354 {+forward-override{forward-socks5 10.0.0.2:2222 .} \
4355 -hide-if-modified-since \
4356 -overwrite-last-modified \
4358 TAG:^User-Agent: fetch libfetch/2\.0$
4367 <!-- ~~~~~ New section ~~~~~ -->
4368 <sect3 renderas="sect4" id="handle-as-empty-document">
4369 <title>handle-as-empty-document</title>
4375 <term>Typical use:</term>
4377 <para>Mark URLs that should be replaced by empty documents <emphasis>if they get blocked</emphasis></para>
4382 <term>Effect:</term>
4385 This action alone doesn't do anything noticeable. It just marks URLs.
4386 If the <literal><link linkend="block">block</link></literal> action <emphasis>also applies</emphasis>,
4387 the presence or absence of this mark decides whether an HTML <quote>BLOCKED</quote>
4388 page, or an empty document will be sent to the client as a substitute for the blocked content.
4389 The <emphasis>empty</emphasis> document isn't literally empty, but actually contains a single space.
4396 <!-- Boolean, Parameterized, Multi-value -->
4398 <para>Boolean.</para>
4403 <term>Parameter:</term>
4415 Some browsers complain about syntax errors if JavaScript documents
4416 are blocked with <application>Privoxy's</application>
4417 default HTML page; this option can be used to silence them.
4418 And of course this action can also be used to eliminate the &my-app;
4419 BLOCKED message in frames.
4422 The content type for the empty document can be specified with
4423 <literal><link linkend="content-type-overwrite">content-type-overwrite{}</link></literal>,
4424 but usually this isn't necessary.
4430 <term>Example usage:</term>
4433 <screen># Block all documents on example.org that end with ".js",
4434 # but send an empty document instead of the usual HTML message.
4435 {+block{Blocked JavaScript} +handle-as-empty-document}
4445 <!-- ~~~~~ New section ~~~~~ -->
4446 <sect3 renderas="sect4" id="handle-as-image">
4447 <title>handle-as-image</title>
4451 <term>Typical use:</term>
4453 <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>
4458 <term>Effect:</term>
4461 This action alone doesn't do anything noticeable. It just marks URLs as images.
4462 If the <literal><link linkend="block">block</link></literal> action <emphasis>also applies</emphasis>,
4463 the presence or absence of this mark decides whether an HTML <quote>blocked</quote>
4464 page, or a replacement image (as determined by the <literal><link
4465 linkend="set-image-blocker">set-image-blocker</link></literal> action) will be sent to the
4466 client as a substitute for the blocked content.
4473 <!-- Boolean, Parameterized, Multi-value -->
4475 <para>Boolean.</para>
4480 <term>Parameter:</term>
4492 The below generic example section is actually part of <filename>default.action</filename>.
4493 It marks all URLs with well-known image file name extensions as images and should
4497 Users will probably only want to use the handle-as-image action in conjunction with
4498 <literal><link linkend="block">block</link></literal>, to block sources of banners, whose URLs don't
4499 reflect the file type, like in the second example section.
4502 Note that you cannot treat HTML pages as images in most cases. For instance, (in-line) ad
4503 frames require an HTML page to be sent, or they won't display properly.
4504 Forcing <literal>handle-as-image</literal> in this situation will not replace the
4505 ad frame with an image, but lead to error messages.
4511 <term>Example usage (sections):</term>
4514 <screen># Generic image extensions:
4517 /.*\.(gif|jpg|jpeg|png|bmp|ico)$
4519 # These don't look like images, but they're banners and should be
4520 # blocked as images:
4522 {+block{Nasty banners.} +handle-as-image}
4523 nasty-banner-server.example.com/junk.cgi\?output=trash
4532 <!-- ~~~~~ New section ~~~~~ -->
4533 <sect3 renderas="sect4" id="hide-accept-language">
4534 <title>hide-accept-language</title>
4540 <term>Typical use:</term>
4542 <para>Pretend to use different language settings.</para>
4547 <term>Effect:</term>
4550 Deletes or replaces the <quote>Accept-Language:</quote> HTTP header in client requests.
4557 <!-- Boolean, Parameterized, Multi-value -->
4559 <para>Parameterized.</para>
4564 <term>Parameter:</term>
4567 Keyword: <quote>block</quote>, or any user defined value.
4576 Faking the browser's language settings can be useful to make a
4577 foreign User-Agent set with
4578 <literal><link linkend="hide-user-agent">hide-user-agent</link></literal>
4582 However some sites with content in different languages check the
4583 <quote>Accept-Language:</quote> to decide which one to take by default.
4584 Sometimes it isn't possible to later switch to another language without
4585 changing the <quote>Accept-Language:</quote> header first.
4588 Therefore it's a good idea to either only change the
4589 <quote>Accept-Language:</quote> header to languages you understand,
4590 or to languages that aren't wide spread.
4593 Before setting the <quote>Accept-Language:</quote> header
4594 to a rare language, you should consider that it helps to
4595 make your requests unique and thus easier to trace.
4596 If you don't plan to change this header frequently,
4597 you should stick to a common language.
4603 <term>Example usage (section):</term>
4606 <screen># Pretend to use Canadian language settings.
4607 {+hide-accept-language{en-ca} \
4608 +hide-user-agent{Mozilla/5.0 (X11; U; OpenBSD i386; en-CA; rv:1.8.0.4) Gecko/20060628 Firefox/1.5.0.4} \
4618 <!-- ~~~~~ New section ~~~~~ -->
4619 <sect3 renderas="sect4" id="hide-content-disposition">
4620 <title>hide-content-disposition</title>
4626 <term>Typical use:</term>
4628 <para>Prevent download menus for content you prefer to view inside the browser.</para>
4633 <term>Effect:</term>
4636 Deletes or replaces the <quote>Content-Disposition:</quote> HTTP header set by some servers.
4643 <!-- Boolean, Parameterized, Multi-value -->
4645 <para>Parameterized.</para>
4650 <term>Parameter:</term>
4653 Keyword: <quote>block</quote>, or any user defined value.
4662 Some servers set the <quote>Content-Disposition:</quote> HTTP header for
4663 documents they assume you want to save locally before viewing them.
4664 The <quote>Content-Disposition:</quote> header contains the file name
4665 the browser is supposed to use by default.
4668 In most browsers that understand this header, it makes it impossible to
4669 <emphasis>just view</emphasis> the document, without downloading it first,
4670 even if it's just a simple text file or an image.
4673 Removing the <quote>Content-Disposition:</quote> header helps
4674 to prevent this annoyance, but some browsers additionally check the
4675 <quote>Content-Type:</quote> header, before they decide if they can
4676 display a document without saving it first. In these cases, you have
4677 to change this header as well, before the browser stops displaying
4681 It is also possible to change the server's file name suggestion
4682 to another one, but in most cases it isn't worth the time to set
4686 This action will probably be removed in the future,
4687 use server-header filters instead.
4693 <term>Example usage:</term>
4696 <screen># Disarm the download link in Sourceforge's patch tracker
4698 +content-type-overwrite{text/plain}\
4699 +hide-content-disposition{block} }
4700 .sourceforge.net/tracker/download\.php</screen>
4708 <!-- ~~~~~ New section ~~~~~ -->
4709 <sect3 renderas="sect4" id="hide-if-modified-since">
4710 <title>hide-if-modified-since</title>
4716 <term>Typical use:</term>
4718 <para>Prevent yet another way to track the user's steps between sessions.</para>
4723 <term>Effect:</term>
4726 Deletes the <quote>If-Modified-Since:</quote> HTTP client header or modifies its value.
4733 <!-- Boolean, Parameterized, Multi-value -->
4735 <para>Parameterized.</para>
4740 <term>Parameter:</term>
4743 Keyword: <quote>block</quote>, or a user defined value that specifies a range of hours.
4752 Removing this header is useful for filter testing, where you want to force a real
4753 reload instead of getting status code <quote>304</quote>, which would cause the
4754 browser to use a cached copy of the page.
4757 Instead of removing the header, <literal>hide-if-modified-since</literal> can
4758 also add or subtract a random amount of time to/from the header's value.
4759 You specify a range of minutes where the random factor should be chosen from and
4760 <application>Privoxy</application> does the rest. A negative value means
4761 subtracting, a positive value adding.
4764 Randomizing the value of the <quote>If-Modified-Since:</quote> makes
4765 it less likely that the server can use the time as a cookie replacement,
4766 but you will run into caching problems if the random range is too high.
4769 It is a good idea to only use a small negative value and let
4770 <literal><link linkend="overwrite-last-modified">overwrite-last-modified</link></literal>
4771 handle the greater changes.
4774 It is also recommended to use this action together with
4775 <literal><link linkend="crunch-if-none-match">crunch-if-none-match</link></literal>,
4776 otherwise it's more or less pointless.
4782 <term>Example usage (section):</term>
4785 <screen># Let the browser revalidate but make tracking based on the time less likely.
4786 {+hide-if-modified-since{-60} \
4787 +overwrite-last-modified{randomize} \
4788 +crunch-if-none-match}
4797 <!-- ~~~~~ New section ~~~~~ -->
4798 <sect3 renderas="sect4" id="hide-from-header">
4799 <title>hide-from-header</title>
4803 <term>Typical use:</term>
4805 <para>Keep your (old and ill) browser from telling web servers your email address</para>
4810 <term>Effect:</term>
4813 Deletes any existing <quote>From:</quote> HTTP header, or replaces it with the
4821 <!-- Boolean, Parameterized, Multi-value -->
4823 <para>Parameterized.</para>
4828 <term>Parameter:</term>
4831 Keyword: <quote>block</quote>, or any user defined value.
4840 The keyword <quote>block</quote> will completely remove the header
4841 (not to be confused with the <literal><link linkend="block">block</link></literal>
4845 Alternately, you can specify any value you prefer to be sent to the web
4846 server. If you do, it is a matter of fairness not to use any address that
4847 is actually used by a real person.
4850 This action is rarely needed, as modern web browsers don't send
4851 <quote>From:</quote> headers anymore.
4857 <term>Example usage:</term>
4860 <screen>+hide-from-header{block}</screen> or
4861 <screen>+hide-from-header{spam-me-senseless@sittingduck.example.com}</screen>
4869 <!-- ~~~~~ New section ~~~~~ -->
4870 <sect3 renderas="sect4" id="hide-referrer">
4871 <title>hide-referrer</title>
4872 <anchor id="hide-referer">
4875 <term>Typical use:</term>
4877 <para>Conceal which link you followed to get to a particular site</para>
4882 <term>Effect:</term>
4885 Deletes the <quote>Referer:</quote> (sic) HTTP header from the client request,
4886 or replaces it with a forged one.
4893 <!-- Boolean, Parameterized, Multi-value -->
4895 <para>Parameterized.</para>
4900 <term>Parameter:</term>
4904 <para><quote>conditional-block</quote> to delete the header completely if the host has changed.</para>
4907 <para><quote>conditional-forge</quote> to forge the header if the host has changed.</para>
4910 <para><quote>block</quote> to delete the header unconditionally.</para>
4913 <para><quote>forge</quote> to pretend to be coming from the homepage of the server we are talking to.</para>
4916 <para>Any other string to set a user defined referrer.</para>
4926 <literal>conditional-block</literal> is the only parameter,
4927 that isn't easily detected in the server's log file. If it blocks the
4928 referrer, the request will look like the visitor used a bookmark or
4929 typed in the address directly.
4932 Leaving the referrer unmodified for requests on the same host
4933 allows the server owner to see the visitor's <quote>click path</quote>,
4934 but in most cases she could also get that information by comparing
4935 other parts of the log file: for example the User-Agent if it isn't
4936 a very common one, or the user's IP address if it doesn't change between
4940 Always blocking the referrer, or using a custom one, can lead to
4941 failures on servers that check the referrer before they answer any
4942 requests, in an attempt to prevent their content from being
4943 embedded or linked to elsewhere.
4946 Both <literal>conditional-block</literal> and <literal>forge</literal>
4947 will work with referrer checks, as long as content and valid referring page
4948 are on the same host. Most of the time that's the case.
4951 <literal>hide-referer</literal> is an alternate spelling of
4952 <literal>hide-referrer</literal> and the two can be can be freely
4953 substituted with each other. (<quote>referrer</quote> is the
4954 correct English spelling, however the HTTP specification has a bug - it
4955 requires it to be spelled as <quote>referer</quote>.)
4961 <term>Example usage:</term>
4964 <screen>+hide-referrer{forge}</screen> or
4965 <screen>+hide-referrer{http://www.yahoo.com/}</screen>
4973 <!-- ~~~~~ New section ~~~~~ -->
4974 <sect3 renderas="sect4" id="hide-user-agent">
4975 <title>hide-user-agent</title>
4979 <term>Typical use:</term>
4981 <para>Try to conceal your type of browser and client operating system</para>
4986 <term>Effect:</term>
4989 Replaces the value of the <quote>User-Agent:</quote> HTTP header
4990 in client requests with the specified value.
4997 <!-- Boolean, Parameterized, Multi-value -->
4999 <para>Parameterized.</para>
5004 <term>Parameter:</term>
5007 Any user-defined string.
5017 This can lead to problems on web sites that depend on looking at this header in
5018 order to customize their content for different browsers (which, by the
5019 way, is <emphasis>NOT</emphasis> the right thing to do: good web sites
5020 work browser-independently).
5024 Using this action in multi-user setups or wherever different types of
5025 browsers will access the same <application>Privoxy</application> is
5026 <emphasis>not recommended</emphasis>. In single-user, single-browser
5027 setups, you might use it to delete your OS version information from
5028 the headers, because it is an invitation to exploit known bugs for your
5029 OS. It is also occasionally useful to forge this in order to access
5030 sites that won't let you in otherwise (though there may be a good
5031 reason in some cases).
5034 More information on known user-agent strings can be found at
5035 <ulink url="http://www.user-agents.org/">http://www.user-agents.org/</ulink>
5037 <ulink url="http://en.wikipedia.org/wiki/User_agent">http://en.wikipedia.org/wiki/User_agent</ulink>.
5043 <term>Example usage:</term>
5046 <screen>+hide-user-agent{Netscape 6.1 (X11; I; Linux 2.4.18 i686)}</screen>
5054 <!-- ~~~~~ New section ~~~~~ -->
5055 <sect3 renderas="sect4" id="limit-connect">
5056 <title>limit-connect</title>
5060 <term>Typical use:</term>
5062 <para>Prevent abuse of <application>Privoxy</application> as a TCP proxy relay or disable SSL for untrusted sites</para>
5067 <term>Effect:</term>
5070 Specifies to which ports HTTP CONNECT requests are allowable.
5077 <!-- Boolean, Parameterized, Multi-value -->
5079 <para>Parameterized.</para>
5084 <term>Parameter:</term>
5087 A comma-separated list of ports or port ranges (the latter using dashes, with the minimum
5088 defaulting to 0 and the maximum to 65K).
5097 By default, i.e. if no <literal>limit-connect</literal> action applies,
5098 <application>Privoxy</application> allows HTTP CONNECT requests to all
5099 ports. Use <literal>limit-connect</literal> if fine-grained control
5100 is desired for some or all destinations.
5103 The CONNECT methods exists in HTTP to allow access to secure websites
5104 (<quote>https://</quote> URLs) through proxies. It works very simply:
5105 the proxy connects to the server on the specified port, and then
5106 short-circuits its connections to the client and to the remote server.
5107 This means CONNECT-enabled proxies can be used as TCP relays very easily.
5110 <application>Privoxy</application> relays HTTPS traffic without seeing
5111 the decoded content. Websites can leverage this limitation to circumvent &my-app;'s
5112 filters. By specifying an invalid port range you can disable HTTPS entirely.
5118 <term>Example usages:</term>
5120 <!-- I had trouble getting the spacing to look right in my browser -->
5121 <!-- I probably have the wrong font setup, bollocks. -->
5122 <!-- Apparently the emphasis tag uses a proportional font no matter what -->
5124 <screen>+limit-connect{443} # Port 443 is OK.
5125 +limit-connect{80,443} # Ports 80 and 443 are OK.
5126 +limit-connect{-3, 7, 20-100, 500-} # Ports less than 3, 7, 20 to 100 and above 500 are OK.
5127 +limit-connect{-} # All ports are OK
5128 +limit-connect{,} # No HTTPS/SSL traffic is allowed</screen>
5136 <!-- ~~~~~ New section ~~~~~ -->
5137 <sect3 renderas="sect4" id="limit-cookie-lifetime">
5138 <title>limit-cookie-lifetime</title>
5142 <term>Typical use:</term>
5144 <para>Limit the lifetime of HTTP cookies to a couple of minutes or hours.</para>
5149 <term>Effect:</term>
5152 Overwrites the expires field in Set-Cookie server headers if it's above the specified limit.
5159 <!-- Boolean, Parameterized, Multi-value -->
5161 <para>Parameterized.</para>
5166 <term>Parameter:</term>
5169 The lifetime limit in minutes, or 0.
5178 This action reduces the lifetime of HTTP cookies coming from the
5179 server to the specified number of minutes, starting from the time
5180 the cookie passes Privoxy.
5183 Cookies with a lifetime below the limit are not modified.
5184 The lifetime of session cookies is set to the specified limit.
5187 The effect of this action depends on the server.
5190 In case of servers which refresh their cookies with each response
5191 (or at least frequently), the lifetime limit set by this action
5193 Thus, a session associated with the cookie continues to work with
5194 this action enabled, as long as a new request is made before the
5195 last limit set is reached.
5198 However, some servers send their cookies once, with a lifetime of several
5199 years (the year 2037 is a popular choice), and do not refresh them
5200 until a certain event in the future, for example the user logging out.
5201 In this case this action may limit the absolute lifetime of the session,
5202 even if requests are made frequently.
5205 If the parameter is <quote>0</quote>, this action behaves like
5206 <literal><link linkend="session-cookies-only">session-cookies-only</link></literal>.
5212 <term>Example usages:</term>
5215 <screen>+limit-cookie-lifetime{60}
5223 <!-- ~~~~~ New section ~~~~~ -->
5224 <sect3 renderas="sect4" id="prevent-compression">
5225 <title>prevent-compression</title>
5229 <term>Typical use:</term>
5232 Ensure that servers send the content uncompressed, so it can be
5233 passed through <literal><link linkend="filter">filter</link></literal>s.
5239 <term>Effect:</term>
5242 Removes the Accept-Encoding header which can be used to ask for compressed transfer.
5249 <!-- Boolean, Parameterized, Multi-value -->
5251 <para>Boolean.</para>
5256 <term>Parameter:</term>
5268 More and more websites send their content compressed by default, which
5269 is generally a good idea and saves bandwidth. But the <literal><link
5270 linkend="filter">filter</link></literal> and
5271 <literal><link linkend="deanimate-gifs">deanimate-gifs</link></literal>
5272 actions need access to the uncompressed data.
5275 When compiled with zlib support (available since &my-app; 3.0.7), content that should be
5276 filtered is decompressed on-the-fly and you don't have to worry about this action.
5277 If you are using an older &my-app; version, or one that hasn't been compiled with zlib
5278 support, this action can be used to convince the server to send the content uncompressed.
5281 Most text-based instances compress very well, the size is seldom decreased by less than 50%,
5282 for markup-heavy instances like news feeds saving more than 90% of the original size isn't
5286 Not using compression will therefore slow down the transfer, and you should only
5287 enable this action if you really need it. As of &my-app; 3.0.7 it's disabled in all
5288 predefined action settings.
5291 Note that some (rare) ill-configured sites don't handle requests for uncompressed
5292 documents correctly. Broken PHP applications tend to send an empty document body,
5293 some IIS versions only send the beginning of the content. If you enable
5294 <literal>prevent-compression</literal> per default, you might want to add
5295 exceptions for those sites. See the example for how to do that.
5301 <term>Example usage (sections):</term>
5305 # Selectively turn off compression, and enable a filter
5307 { +filter{tiny-textforms} +prevent-compression }
5308 # Match only these sites
5313 # Or instead, we could set a universal default:
5315 { +prevent-compression }
5318 # Then maybe make exceptions for broken sites:
5320 { -prevent-compression }
5321 .compusa.com/</screen>
5330 <!-- ~~~~~ New section ~~~~~ -->
5331 <sect3 renderas="sect4" id="overwrite-last-modified">
5332 <title>overwrite-last-modified</title>
5338 <term>Typical use:</term>
5340 <para>Prevent yet another way to track the user's steps between sessions.</para>
5345 <term>Effect:</term>
5348 Deletes the <quote>Last-Modified:</quote> HTTP server header or modifies its value.
5355 <!-- Boolean, Parameterized, Multi-value -->
5357 <para>Parameterized.</para>
5362 <term>Parameter:</term>
5365 One of the keywords: <quote>block</quote>, <quote>reset-to-request-time</quote>
5366 and <quote>randomize</quote>
5375 Removing the <quote>Last-Modified:</quote> header is useful for filter
5376 testing, where you want to force a real reload instead of getting status
5377 code <quote>304</quote>, which would cause the browser to reuse the old
5378 version of the page.
5381 The <quote>randomize</quote> option overwrites the value of the
5382 <quote>Last-Modified:</quote> header with a randomly chosen time
5383 between the original value and the current time. In theory the server
5384 could send each document with a different <quote>Last-Modified:</quote>
5385 header to track visits without using cookies. <quote>Randomize</quote>
5386 makes it impossible and the browser can still revalidate cached documents.
5389 <quote>reset-to-request-time</quote> overwrites the value of the
5390 <quote>Last-Modified:</quote> header with the current time. You could use
5391 this option together with
5392 <literal><link linkend="hide-if-modified-since">hide-if-modified-since</link></literal>
5393 to further customize your random range.
5396 The preferred parameter here is <quote>randomize</quote>. It is safe
5397 to use, as long as the time settings are more or less correct.
5398 If the server sets the <quote>Last-Modified:</quote> header to the time
5399 of the request, the random range becomes zero and the value stays the same.
5400 Therefore you should later randomize it a second time with
5401 <literal><link linkend="hide-if-modified-since">hided-if-modified-since</link></literal>,
5405 It is also recommended to use this action together with
5406 <literal><link linkend="crunch-if-none-match">crunch-if-none-match</link></literal>.
5412 <term>Example usage:</term>
5415 <screen># Let the browser revalidate without being tracked across sessions
5416 { +hide-if-modified-since{-60} \
5417 +overwrite-last-modified{randomize} \
5418 +crunch-if-none-match}
5427 <!-- ~~~~~ New section ~~~~~ -->
5428 <sect3 renderas="sect4" id="redirect">
5429 <title>redirect</title>
5435 <term>Typical use:</term>
5438 Redirect requests to other sites.
5444 <term>Effect:</term>
5447 Convinces the browser that the requested document has been moved
5448 to another location and the browser should get it from there.
5455 <!-- Boolean, Parameterized, Multi-value -->
5457 <para>Parameterized</para>
5462 <term>Parameter:</term>
5465 An absolute URL or a single pcrs command.
5474 Requests to which this action applies are answered with a
5475 HTTP redirect to URLs of your choosing. The new URL is
5476 either provided as parameter, or derived by applying a
5477 single pcrs command to the original URL.
5480 The syntax for pcrs commands is documented in the
5481 <link linkend="filter-file">filter file</link> section.
5484 Requests can't be blocked and redirected at the same time,
5485 applying this action together with
5486 <literal><link linkend="block">block</link></literal>
5487 is a configuration error. Currently the request is blocked
5488 and an error message logged, the behavior may change in the
5489 future and result in Privoxy rejecting the action file.
5492 This action can be combined with
5493 <literal><link linkend="fast-redirects">fast-redirects{check-decoded-url}</link></literal>
5494 to redirect to a decoded version of a rewritten URL.
5497 Use this action carefully, make sure not to create redirection loops
5498 and be aware that using your own redirects might make it
5499 possible to fingerprint your requests.
5502 In case of problems with your redirects, or simply to watch
5503 them working, enable <link linkend="DEBUG">debug 128</link>.
5509 <term>Example usages:</term>
5512 <screen># Replace example.com's style sheet with another one
5513 { +redirect{http://localhost/css-replacements/example.com.css} }
5514 example.com/stylesheet\.css
5516 # Create a short, easy to remember nickname for a favorite site
5517 # (relies on the browser to accept and forward invalid URLs to &my-app;)
5518 { +redirect{https://www.privoxy.org/user-manual/actions-file.html} }
5521 # Always use the expanded view for Undeadly.org articles
5522 # (Note the $ at the end of the URL pattern to make sure
5523 # the request for the rewritten URL isn't redirected as well)
5524 {+redirect{s@$@&mode=expanded@}}
5525 undeadly.org/cgi\?action=article&sid=\d*$
5527 # Redirect Google search requests to MSN
5528 {+redirect{s@^http://[^/]*/search\?q=([^&]*).*@http://search.msn.com/results.aspx?q=$1@}}
5531 # Redirect MSN search requests to Yahoo
5532 {+redirect{s@^http://[^/]*/results\.aspx\?q=([^&]*).*@http://search.yahoo.com/search?p=$1@}}
5533 search.msn.com//results\.aspx\?q=
5535 # Redirect http://example.com/&bla=fasel&toChange=foo (and any other value but "bar")
5536 # to http://example.com/&bla=fasel&toChange=bar
5538 # The URL pattern makes sure that the following request isn't redirected again.
5539 {+redirect{s@toChange=[^&]+@toChange=bar@}}
5540 example.com/.*toChange=(?!bar)
5542 # Add a shortcut to look up illumos bugs
5543 {+redirect{s@^http://i([0-9]+)/.*@https://www.illumos.org/issues/$1@}}
5544 # Redirected URL = http://i4974/
5545 # Redirect Destination = https://www.illumos.org/issues/4974
5546 i[0-9][0-9][0-9][0-9]*/
5548 # Redirect remote requests for this manual
5549 # to the local version delivered by Privoxy
5550 {+redirect{s@^http://www@http://config@}}
5551 www.privoxy.org/user-manual/</screen>
5560 <!-- ~~~~~ New section ~~~~~ -->
5561 <sect3 renderas="sect4" id="server-header-filter">
5562 <title>server-header-filter</title>
5566 <term>Typical use:</term>
5569 Rewrite or remove single server headers.
5575 <term>Effect:</term>
5578 All server headers to which this action applies are filtered on-the-fly
5579 through the specified regular expression based substitutions.
5586 <!-- boolean, parameterized, Multi-value -->
5588 <para>Multi-value.</para>
5593 <term>Parameter:</term>
5596 The name of a server-header filter, as defined in one of the
5597 <link linkend="filter-file">filter files</link>.
5606 Server-header filters are applied to each header on its own, not to
5607 all at once. This makes it easier to diagnose problems, but on the downside
5608 you can't write filters that only change header x if header y's value is z.
5609 You can do that by using tags though.
5612 Server-header filters are executed after the other header actions have finished
5613 and use their output as input.
5616 Please refer to the <link linkend="filter-file">filter file chapter</link>
5617 to learn which server-header filters are available by default, and how to
5624 <term>Example usage (section):</term>
5628 {+server-header-filter{html-to-xml}}
5629 example.org/xml-instance-that-is-delivered-as-html
5631 {+server-header-filter{xml-to-html}}
5632 example.org/instance-that-is-delivered-as-xml-but-is-not
5642 <!-- ~~~~~ New section ~~~~~ -->
5643 <sect3 renderas="sect4" id="server-header-tagger">
5644 <title>server-header-tagger</title>
5648 <term>Typical use:</term>
5651 Enable or disable filters based on the Content-Type header.
5657 <term>Effect:</term>
5660 Server headers to which this action applies are filtered on-the-fly through
5661 the specified regular expression based substitutions, the result is used as
5669 <!-- boolean, parameterized, Multi-value -->
5671 <para>Multi-value.</para>
5676 <term>Parameter:</term>
5679 The name of a server-header tagger, as defined in one of the
5680 <link linkend="filter-file">filter files</link>.
5689 Server-header taggers are applied to each header on its own,
5690 and as the header isn't modified, each tagger <quote>sees</quote>
5694 Server-header taggers are executed before all other header actions
5695 that modify server headers. Their tags can be used to control
5696 all of the other server-header actions, the content filters
5697 and the crunch actions (<link linkend="redirect">redirect</link>
5698 and <link linkend="block">block</link>).
5701 Obviously crunching based on tags created by server-header taggers
5702 doesn't prevent the request from showing up in the server's log file.
5709 <term>Example usage (section):</term>
5713 # Tag every request with the content type declared by the server
5714 {+server-header-tagger{content-type}}
5717 # If the response has a tag starting with 'image/' enable an external
5718 # filter that only applies to images.
5720 # Note that the filter is not available by default, it's just a
5721 # <literal><link linkend="external-filter-syntax">silly example</link></literal>.
5722 {+external-filter{rotate-image} +force-text-mode}
5733 <!-- ~~~~~ New section ~~~~~ -->
5734 <sect3 renderas="sect4" id="session-cookies-only">
5735 <title>session-cookies-only</title>
5739 <term>Typical use:</term>
5742 Allow only temporary <quote>session</quote> cookies (for the current
5743 browser session <emphasis>only</emphasis>).
5749 <term>Effect:</term>
5752 Deletes the <quote>expires</quote> field from <quote>Set-Cookie:</quote>
5753 server headers. Most browsers will not store such cookies permanently and
5754 forget them in between sessions.
5761 <!-- Boolean, Parameterized, Multi-value -->
5763 <para>Boolean.</para>
5768 <term>Parameter:</term>
5780 This is less strict than <literal><link linkend="crunch-incoming-cookies">crunch-incoming-cookies</link></literal> /
5781 <literal><link linkend="crunch-outgoing-cookies">crunch-outgoing-cookies</link></literal> and allows you to browse
5782 websites that insist or rely on setting cookies, without compromising your privacy too badly.
5785 Most browsers will not permanently store cookies that have been processed by
5786 <literal>session-cookies-only</literal> and will forget about them between sessions.
5787 This makes profiling cookies useless, but won't break sites which require cookies so
5788 that you can log in for transactions. This is generally turned on for all
5789 sites, and is the recommended setting.
5792 It makes <emphasis>no sense at all</emphasis> to use <literal>session-cookies-only</literal>
5793 together with <literal><link linkend="crunch-incoming-cookies">crunch-incoming-cookies</link></literal> or
5794 <literal><link linkend="crunch-outgoing-cookies">crunch-outgoing-cookies</link></literal>. If you do, cookies
5795 will be plainly killed.
5798 Note that it is up to the browser how it handles such cookies without an <quote>expires</quote>
5799 field. If you use an exotic browser, you might want to try it out to be sure.
5802 This setting also has no effect on cookies that may have been stored
5803 previously by the browser before starting <application>Privoxy</application>.
5804 These would have to be removed manually.
5807 <application>Privoxy</application> also uses
5808 the <link linkend="filter-content-cookies">content-cookies filter</link>
5809 to block some types of cookies. Content cookies are not effected by
5810 <literal>session-cookies-only</literal>.
5816 <term>Example usage:</term>
5819 <screen>+session-cookies-only</screen>
5827 <!-- ~~~~~ New section ~~~~~ -->
5828 <sect3 renderas="sect4" id="set-image-blocker">
5829 <title>set-image-blocker</title>
5833 <term>Typical use:</term>
5835 <para>Choose the replacement for blocked images</para>
5840 <term>Effect:</term>
5843 This action alone doesn't do anything noticeable. If <emphasis>both</emphasis>
5844 <literal><link linkend="block">block</link></literal> <emphasis>and</emphasis> <literal><link
5845 linkend="handle-as-image">handle-as-image</link></literal> <emphasis>also</emphasis>
5846 apply, i.e. if the request is to be blocked as an image,
5847 <emphasis>then</emphasis> the parameter of this action decides what will be
5848 sent as a replacement.
5855 <!-- Boolean, Parameterized, Multi-value -->
5857 <para>Parameterized.</para>
5862 <term>Parameter:</term>
5867 <quote>pattern</quote> to send a built-in checkerboard pattern image. The image is visually
5868 decent, scales very well, and makes it obvious where banners were busted.
5873 <quote>blank</quote> to send a built-in transparent image. This makes banners disappear
5874 completely, but makes it hard to detect where <application>Privoxy</application> has blocked
5875 images on a given page and complicates troubleshooting if <application>Privoxy</application>
5876 has blocked innocent images, like navigation icons.
5881 <quote><replaceable class="parameter">target-url</replaceable></quote> to
5882 send a redirect to <replaceable class="parameter">target-url</replaceable>. You can redirect
5883 to any image anywhere, even in your local filesystem via <quote>file:///</quote> URL.
5884 (But note that not all browsers support redirecting to a local file system).
5887 A good application of redirects is to use special <application>Privoxy</application>-built-in
5888 URLs, which send the built-in images, as <replaceable class="parameter">target-url</replaceable>.
5889 This has the same visual effect as specifying <quote>blank</quote> or <quote>pattern</quote> in
5890 the first place, but enables your browser to cache the replacement image, instead of requesting
5891 it over and over again.
5902 The URLs for the built-in images are <quote>http://config.privoxy.org/send-banner?type=<replaceable
5903 class="parameter">type</replaceable></quote>, where <replaceable class="parameter">type</replaceable> is
5904 either <quote>blank</quote> or <quote>pattern</quote>.
5907 There is a third (advanced) type, called <quote>auto</quote>. It is <emphasis>NOT</emphasis> to be
5908 used in <literal>set-image-blocker</literal>, but meant for use from <link linkend="filter-file">filters</link>.
5909 Auto will select the type of image that would have applied to the referring page, had it been an image.
5915 <term>Example usage:</term>
5921 <screen>+set-image-blocker{pattern}</screen>
5924 Redirect to the BSD daemon:
5927 <screen>+set-image-blocker{http://www.freebsd.org/gifs/dae_up3.gif}</screen>
5930 Redirect to the built-in pattern for better caching:
5933 <screen>+set-image-blocker{http://config.privoxy.org/send-banner?type=pattern}</screen>
5941 <!-- ~~~~~ New section ~~~~~ -->
5942 <sect3 id="summary">
5943 <title>Summary</title>
5945 Note that many of these actions have the potential to cause a page to
5946 misbehave, possibly even not to display at all. There are many ways
5947 a site designer may choose to design his site, and what HTTP header
5948 content, and other criteria, he may depend on. There is no way to have hard
5949 and fast rules for all sites. See the <link
5950 linkend="ACTIONSANAT">Appendix</link> for a brief example on troubleshooting
5956 <!-- ~~~~~ New section ~~~~~ -->
5957 <sect2 id="aliases">
5958 <title>Aliases</title>
5960 Custom <quote>actions</quote>, known to <application>Privoxy</application>
5961 as <quote>aliases</quote>, can be defined by combining other actions.
5962 These can in turn be invoked just like the built-in actions.
5963 Currently, an alias name can contain any character except space, tab,
5965 <quote>{</quote> and <quote>}</quote>, but we <emphasis>strongly
5966 recommend</emphasis> that you only use <quote>a</quote> to <quote>z</quote>,
5967 <quote>0</quote> to <quote>9</quote>, <quote>+</quote>, and <quote>-</quote>.
5968 Alias names are not case sensitive, and are not required to start with a
5969 <quote>+</quote> or <quote>-</quote> sign, since they are merely textually
5973 Aliases can be used throughout the actions file, but they <emphasis>must be
5974 defined in a special section at the top of the file!</emphasis>
5975 And there can only be one such section per actions file. Each actions file may
5976 have its own alias section, and the aliases defined in it are only visible
5980 There are two main reasons to use aliases: One is to save typing for frequently
5981 used combinations of actions, the other one is a gain in flexibility: If you
5982 decide once how you want to handle shops by defining an alias called
5983 <quote>shop</quote>, you can later change your policy on shops in
5984 <emphasis>one</emphasis> place, and your changes will take effect everywhere
5985 in the actions file where the <quote>shop</quote> alias is used. Calling aliases
5986 by their purpose also makes your actions files more readable.
5989 Currently, there is one big drawback to using aliases, though:
5990 <application>Privoxy</application>'s built-in web-based action file
5991 editor honors aliases when reading the actions files, but it expands
5992 them before writing. So the effects of your aliases are of course preserved,
5993 but the aliases themselves are lost when you edit sections that use aliases
5998 Now let's define some aliases...
6003 # Useful custom aliases we can use later.
6005 # Note the (required!) section header line and that this section
6006 # must be at the top of the actions file!
6010 # These aliases just save typing later:
6011 # (Note that some already use other aliases!)
6013 +crunch-all-cookies = +<link linkend="CRUNCH-INCOMING-COOKIES">crunch-incoming-cookies</link> +<link linkend="CRUNCH-OUTGOING-COOKIES">crunch-outgoing-cookies</link>
6014 -crunch-all-cookies = -<link linkend="CRUNCH-INCOMING-COOKIES">crunch-incoming-cookies</link> -<link linkend="CRUNCH-OUTGOING-COOKIES">crunch-outgoing-cookies</link>
6015 +block-as-image = +block{Blocked image.} +handle-as-image
6016 allow-all-cookies = -crunch-all-cookies -<link linkend="SESSION-COOKIES-ONLY">session-cookies-only</link> -<link linkend="FILTER-CONTENT-COOKIES">filter{content-cookies}</link>
6018 # These aliases define combinations of actions
6019 # that are useful for certain types of sites:
6021 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>
6023 shop = -crunch-all-cookies -<link linkend="FILTER-ALL-POPUPS">filter{all-popups}</link>
6025 # Short names for other aliases, for really lazy people ;-)
6027 c0 = +crunch-all-cookies
6028 c1 = -crunch-all-cookies</screen>
6032 ...and put them to use. These sections would appear in the lower part of an
6033 actions file and define exceptions to the default actions (as specified further
6034 up for the <quote>/</quote> pattern):
6039 # These sites are either very complex or very keen on
6040 # user data and require minimal interference to work:
6043 .office.microsoft.com
6044 .windowsupdate.microsoft.com
6045 # Gmail is really mail.google.com, not gmail.com
6049 # Allow cookies (for setting and retrieving your customer data)
6053 .worldpay.com # for quietpc.com
6056 # These shops require pop-ups:
6058 {-filter{all-popups} -filter{unsolicited-popups}}
6060 .overclockers.co.uk</screen>
6064 Aliases like <quote>shop</quote> and <quote>fragile</quote> are typically used for
6065 <quote>problem</quote> sites that require more than one action to be disabled
6066 in order to function properly.
6072 <!-- ~~~~~ New section ~~~~~ -->
6073 <sect2 id="act-examples">
6074 <title>Actions Files Tutorial</title>
6076 The above chapters have shown <link linkend="actions-file">which actions files
6077 there are and how they are organized</link>, how actions are <link
6078 linkend="actions">specified</link> and <link linkend="actions-apply">applied
6079 to URLs</link>, how <link linkend="af-patterns">patterns</link> work, and how to
6080 define and use <link linkend="aliases">aliases</link>. Now, let's look at an
6081 example <filename>match-all.action</filename>, <filename>default.action</filename>
6082 and <filename>user.action</filename> file and see how all these pieces come together:
6085 <sect3 id="match-all">
6086 <title>match-all.action</title>
6088 Remember <emphasis>all actions are disabled when matching starts</emphasis>,
6089 so we have to explicitly enable the ones we want.
6093 While the <filename>match-all.action</filename> file only contains a
6094 single section, it is probably the most important one. It has only one
6095 pattern, <quote><literal>/</literal></quote>, but this pattern
6096 <link linkend="af-patterns">matches all URLs</link>. Therefore, the set of
6097 actions used in this <quote>default</quote> section <emphasis>will
6098 be applied to all requests as a start</emphasis>. It can be partly or
6099 wholly overridden by other actions files like <filename>default.action</filename>
6100 and <filename>user.action</filename>, but it will still be largely responsible
6101 for your overall browsing experience.
6105 Again, at the start of matching, all actions are disabled, so there is
6106 no need to disable any actions here. (Remember: a <quote>+</quote>
6107 preceding the action name enables the action, a <quote>-</quote> disables!).
6108 Also note how this long line has been made more readable by splitting it into
6109 multiple lines with line continuation.
6115 +<link linkend="CHANGE-X-FORWARDED-FOR">change-x-forwarded-for{block}</link> \
6116 +<link linkend="HIDE-FROM-HEADER">hide-from-header{block}</link> \
6117 +<link linkend="SET-IMAGE-BLOCKER">set-image-blocker{pattern}</link> \
6124 The default behavior is now set.
6128 <sect3 id="default-action">
6129 <title>default.action</title>
6132 If you aren't a developer, there's no need for you to edit the
6133 <filename>default.action</filename> file. It is maintained by
6134 the &my-app; developers and if you disagree with some of the
6135 sections, you should overrule them in your <filename>user.action</filename>.
6139 Understanding the <filename>default.action</filename> file can
6140 help you with your <filename>user.action</filename>, though.
6144 The first section in this file is a special section for internal use
6145 that prevents older &my-app; versions from reading the file:
6150 ##########################################################################
6151 # Settings -- Don't change! For internal Privoxy use ONLY.
6152 ##########################################################################
6154 for-privoxy-version=3.0.11</screen>
6158 After that comes the (optional) alias section. We'll use the example
6159 section from the above <link linkend="aliases">chapter on aliases</link>,
6160 that also explains why and how aliases are used:
6165 ##########################################################################
6167 ##########################################################################
6170 # These aliases just save typing later:
6171 # (Note that some already use other aliases!)
6173 +crunch-all-cookies = +<link linkend="CRUNCH-INCOMING-COOKIES">crunch-incoming-cookies</link> +<link linkend="CRUNCH-OUTGOING-COOKIES">crunch-outgoing-cookies</link>
6174 -crunch-all-cookies = -<link linkend="CRUNCH-INCOMING-COOKIES">crunch-incoming-cookies</link> -<link linkend="CRUNCH-OUTGOING-COOKIES">crunch-outgoing-cookies</link>
6175 +block-as-image = +block{Blocked image.} +handle-as-image
6176 mercy-for-cookies = -crunch-all-cookies -<link linkend="SESSION-COOKIES-ONLY">session-cookies-only</link> -<link linkend="FILTER-CONTENT-COOKIES">filter{content-cookies}</link>
6178 # These aliases define combinations of actions
6179 # that are useful for certain types of sites:
6181 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>
6182 shop = -crunch-all-cookies -<link linkend="FILTER-ALL-POPUPS">filter{all-popups}</link></screen>
6186 The first of our specialized sections is concerned with <quote>fragile</quote>
6187 sites, i.e. sites that require minimum interference, because they are either
6188 very complex or very keen on tracking you (and have mechanisms in place that
6189 make them unusable for people who avoid being tracked). We will use
6190 our pre-defined <literal>fragile</literal> alias instead of stating the list
6191 of actions explicitly:
6196 ##########################################################################
6197 # Exceptions for sites that'll break under the default action set:
6198 ##########################################################################
6200 # "Fragile" Use a minimum set of actions for these sites (see alias above):
6203 .office.microsoft.com # surprise, surprise!
6204 .windowsupdate.microsoft.com
6205 mail.google.com</screen>
6209 Shopping sites are not as fragile, but they typically
6210 require cookies to log in, and pop-up windows for shopping
6211 carts or item details. Again, we'll use a pre-defined alias:
6220 .worldpay.com # for quietpc.com
6222 .scan.co.uk</screen>
6226 The <literal><link linkend="FAST-REDIRECTS">fast-redirects</link></literal>
6227 action, which may have been enabled in <filename>match-all.action</filename>,
6228 breaks some sites. So disable it for popular sites where we know it misbehaves:
6233 { -<link linkend="FAST-REDIRECTS">fast-redirects</link> }
6237 .altavista.com/.*(like|url|link):http
6238 .altavista.com/trans.*urltext=http
6239 .nytimes.com</screen>
6243 It is important that <application>Privoxy</application> knows which
6244 URLs belong to images, so that <emphasis>if</emphasis> they are to
6245 be blocked, a substitute image can be sent, rather than an HTML page.
6246 Contacting the remote site to find out is not an option, since it
6247 would destroy the loading time advantage of banner blocking, and it
6248 would feed the advertisers information about you. We can mark any
6249 URL as an image with the <literal><link
6250 linkend="handle-as-image">handle-as-image</link></literal> action,
6251 and marking all URLs that end in a known image file extension is a
6257 ##########################################################################
6259 ##########################################################################
6261 # Define which file types will be treated as images, in case they get
6262 # blocked further down this file:
6264 { +<link linkend="HANDLE-AS-IMAGE">handle-as-image</link> }
6265 /.*\.(gif|jpe?g|png|bmp|ico)$</screen>
6269 And then there are known banner sources. They often use scripts to
6270 generate the banners, so it won't be visible from the URL that the
6271 request is for an image. Hence we block them <emphasis>and</emphasis>
6272 mark them as images in one go, with the help of our
6273 <literal>+block-as-image</literal> alias defined above. (We could of
6274 course just as well use <literal>+<link linkend="block">block</link>
6275 +<link linkend="handle-as-image">handle-as-image</link></literal> here.)
6276 Remember that the type of the replacement image is chosen by the
6277 <literal><link linkend="set-image-blocker">set-image-blocker</link></literal>
6278 action. Since all URLs have matched the default section with its
6279 <literal>+<link linkend="set-image-blocker">set-image-blocker</link>{pattern}</literal>
6280 action before, it still applies and needn't be repeated:
6285 # Known ad generators:
6290 .ad.*.doubleclick.net
6291 .a.yimg.com/(?:(?!/i/).)*$
6292 .a[0-9].yimg.com/(?:(?!/i/).)*$
6298 One of the most important jobs of <application>Privoxy</application>
6299 is to block banners. Many of these can be <quote>blocked</quote>
6300 by the <literal><link linkend="filter">filter</link>{banners-by-size}</literal>
6301 action, which we enabled above, and which deletes the references to banner
6302 images from the pages while they are loaded, so the browser doesn't request
6303 them anymore, and hence they don't need to be blocked here. But this naturally
6304 doesn't catch all banners, and some people choose not to use filters, so we
6305 need a comprehensive list of patterns for banner URLs here, and apply the
6306 <literal><link linkend="block">block</link></literal> action to them.
6309 First comes many generic patterns, which do most of the work, by
6310 matching typical domain and path name components of banners. Then comes
6311 a list of individual patterns for specific sites, which is omitted here
6312 to keep the example short:
6317 ##########################################################################
6318 # Block these fine banners:
6319 ##########################################################################
6320 { <link linkend="BLOCK">+block{Banner ads.}</link> }
6328 /.*count(er)?\.(pl|cgi|exe|dll|asp|php[34]?)
6329 /(?:.*/)?(publicite|werbung|rekla(ma|me|am)|annonse|maino(kset|nta|s)?)/
6331 # Site-specific patterns (abbreviated):
6333 .hitbox.com</screen>
6337 It's quite remarkable how many advertisers actually call their banner
6338 servers ads.<replaceable>company</replaceable>.com, or call the directory
6339 in which the banners are stored literally <quote>banners</quote>. So the above
6340 generic patterns are surprisingly effective.
6343 But being very generic, they necessarily also catch URLs that we don't want
6344 to block. The pattern <literal>.*ads.</literal> e.g. catches
6345 <quote>nasty-<emphasis>ads</emphasis>.nasty-corp.com</quote> as intended,
6346 but also <quote>downlo<emphasis>ads</emphasis>.sourcefroge.net</quote> or
6347 <quote><emphasis>ads</emphasis>l.some-provider.net.</quote> So here come some
6348 well-known exceptions to the <literal>+<link linkend="BLOCK">block</link></literal>
6352 Note that these are exceptions to exceptions from the default! Consider the URL
6353 <quote>downloads.sourcefroge.net</quote>: Initially, all actions are deactivated,
6354 so it wouldn't get blocked. Then comes the defaults section, which matches the
6355 URL, but just deactivates the <literal><link linkend="BLOCK">block</link></literal>
6356 action once again. Then it matches <literal>.*ads.</literal>, an exception to the
6357 general non-blocking policy, and suddenly
6358 <literal><link linkend="BLOCK">+block</link></literal> applies. And now, it'll match
6359 <literal>.*loads.</literal>, where <literal><link linkend="BLOCK">-block</link></literal>
6360 applies, so (unless it matches <emphasis>again</emphasis> further down) it ends up
6361 with no <literal><link linkend="BLOCK">block</link></literal> action applying.
6366 ##########################################################################
6367 # Save some innocent victims of the above generic block patterns:
6368 ##########################################################################
6372 { -<link linkend="BLOCK">block</link> }
6373 adv[io]*. # (for advogato.org and advice.*)
6374 adsl. # (has nothing to do with ads)
6375 adobe. # (has nothing to do with ads either)
6376 ad[ud]*. # (adult.* and add.*)
6377 .edu # (universities don't host banners (yet!))
6378 .*loads. # (downloads, uploads etc)
6386 www.globalintersec.com/adv # (adv = advanced)
6387 www.ugu.com/sui/ugu/adv</screen>
6391 Filtering source code can have nasty side effects,
6392 so make an exception for our friends at sourceforge.net,
6393 and all paths with <quote>cvs</quote> in them. Note that
6394 <literal>-<link linkend="FILTER">filter</link></literal>
6395 disables <emphasis>all</emphasis> filters in one fell swoop!
6400 # Don't filter code!
6402 { -<link linkend="FILTER">filter</link> }
6407 .sourceforge.net</screen>
6411 The actual <filename>default.action</filename> is of course much more
6412 comprehensive, but we hope this example made clear how it works.
6417 <sect3 id="user-action"><title>user.action</title>
6420 So far we are painting with a broad brush by setting general policies,
6421 which would be a reasonable starting point for many people. Now,
6422 you might want to be more specific and have customized rules that
6423 are more suitable to your personal habits and preferences. These would
6424 be for narrowly defined situations like your ISP or your bank, and should
6425 be placed in <filename>user.action</filename>, which is parsed after all other
6426 actions files and hence has the last word, over-riding any previously
6427 defined actions. <filename>user.action</filename> is also a
6428 <emphasis>safe</emphasis> place for your personal settings, since
6429 <filename>default.action</filename> is actively maintained by the
6430 <application>Privoxy</application> developers and you'll probably want
6431 to install updated versions from time to time.
6435 So let's look at a few examples of things that one might typically do in
6436 <filename>user.action</filename>:
6440 <!-- brief sample user.action here -->
6444 # My user.action file. <fred@example.com></screen>
6448 As <link linkend="aliases">aliases</link> are local to the actions
6449 file that they are defined in, you can't use the ones from
6450 <filename>default.action</filename>, unless you repeat them here:
6455 # Aliases are local to the file they are defined in.
6456 # (Re-)define aliases for this file:
6460 # These aliases just save typing later, and the alias names should
6461 # be self explanatory.
6463 +crunch-all-cookies = +crunch-incoming-cookies +crunch-outgoing-cookies
6464 -crunch-all-cookies = -crunch-incoming-cookies -crunch-outgoing-cookies
6465 allow-all-cookies = -crunch-all-cookies -session-cookies-only
6466 allow-popups = -filter{all-popups}
6467 +block-as-image = +block{Blocked as image.} +handle-as-image
6468 -block-as-image = -block
6470 # These aliases define combinations of actions that are useful for
6471 # certain types of sites:
6473 fragile = -block -crunch-all-cookies -filter -fast-redirects -hide-referrer
6474 shop = -crunch-all-cookies allow-popups
6476 # Allow ads for selected useful free sites:
6478 allow-ads = -block -filter{banners-by-size} -filter{banners-by-link}
6480 # Alias for specific file types that are text, but might have conflicting
6481 # MIME types. We want the browser to force these to be text documents.
6482 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>
6487 Say you have accounts on some sites that you visit regularly, and
6488 you don't want to have to log in manually each time. So you'd like
6489 to allow persistent cookies for these sites. The
6490 <literal>allow-all-cookies</literal> alias defined above does exactly
6491 that, i.e. it disables crunching of cookies in any direction, and the
6492 processing of cookies to make them only temporary.
6497 { allow-all-cookies }
6501 .redhat.com</screen>
6505 Your bank is allergic to some filter, but you don't know which, so you disable them all:
6510 { -<link linkend="FILTER">filter</link> }
6511 .your-home-banking-site.com</screen>
6515 Some file types you may not want to filter for various reasons:
6520 # Technical documentation is likely to contain strings that might
6521 # erroneously get altered by the JavaScript-oriented filters:
6526 # And this stupid host sends streaming video with a wrong MIME type,
6527 # so that Privoxy thinks it is getting HTML and starts filtering:
6529 stupid-server.example.com/</screen>
6533 Example of a simple <link linkend="BLOCK">block</link> action. Say you've
6534 seen an ad on your favourite page on example.com that you want to get rid of.
6535 You have right-clicked the image, selected <quote>copy image location</quote>
6536 and pasted the URL below while removing the leading http://, into a
6537 <literal>{ +block{} }</literal> section. Note that <literal>{ +handle-as-image
6538 }</literal> need not be specified, since all URLs ending in
6539 <literal>.gif</literal> will be tagged as images by the general rules as set
6540 in default.action anyway:
6545 { +<link linkend="BLOCK">block</link>{Nasty ads.} }
6546 www.example.com/nasty-ads/sponsor\.gif
6547 another.example.net/more/junk/here/</screen>
6551 The URLs of dynamically generated banners, especially from large banner
6552 farms, often don't use the well-known image file name extensions, which
6553 makes it impossible for <application>Privoxy</application> to guess
6554 the file type just by looking at the URL.
6555 You can use the <literal>+block-as-image</literal> alias defined above for
6557 Note that objects which match this rule but then turn out NOT to be an
6558 image are typically rendered as a <quote>broken image</quote> icon by the
6559 browser. Use cautiously.
6568 ar.atwola.com/</screen>
6572 Now you noticed that the default configuration breaks Forbes Magazine,
6573 but you were too lazy to find out which action is the culprit, and you
6574 were again too lazy to give <link linkend="contact">feedback</link>, so
6575 you just used the <literal>fragile</literal> alias on the site, and
6576 -- <emphasis>whoa!</emphasis> -- it worked. The <literal>fragile</literal>
6577 aliases disables those actions that are most likely to break a site. Also,
6578 good for testing purposes to see if it is <application>Privoxy</application>
6579 that is causing the problem or not. We later find other regular sites
6580 that misbehave, and add those to our personalized list of troublemakers:
6588 .mybank.com</screen>
6592 You like the <quote>fun</quote> text replacements in <filename>default.filter</filename>,
6593 but it is disabled in the distributed actions file.
6594 So you'd like to turn it on in your private,
6595 update-safe config, once and for all:
6600 { +<link linkend="filter-fun">filter{fun}</link> }
6601 / # For ALL sites!</screen>
6605 Note that the above is not really a good idea: There are exceptions
6606 to the filters in <filename>default.action</filename> for things that
6607 really shouldn't be filtered, like code on CVS->Web interfaces. Since
6608 <filename>user.action</filename> has the last word, these exceptions
6609 won't be valid for the <quote>fun</quote> filtering specified here.
6613 You might also worry about how your favourite free websites are
6614 funded, and find that they rely on displaying banner advertisements
6615 to survive. So you might want to specifically allow banners for those
6616 sites that you feel provide value to you:
6628 Note that <literal>allow-ads</literal> has been aliased to
6629 <literal>-<link linkend="block">block</link></literal>,
6630 <literal>-<link linkend="filter-banners-by-size">filter{banners-by-size}</link></literal>, and
6631 <literal>-<link linkend="filter-banners-by-link">filter{banners-by-link}</link></literal> above.
6635 Invoke another alias here to force an over-ride of the MIME type <literal>
6636 application/x-sh</literal> which typically would open a download type
6637 dialog. In my case, I want to look at the shell script, and then I can save
6638 it should I choose to.
6648 <filename>user.action</filename> is generally the best place to define
6649 exceptions and additions to the default policies of
6650 <filename>default.action</filename>. Some actions are safe to have their
6651 default policies set here though. So let's set a default policy to have a
6652 <quote>blank</quote> image as opposed to the checkerboard pattern for
6653 <emphasis>ALL</emphasis> sites. <quote>/</quote> of course matches all URL
6659 { +<link linkend="set-image-blocker">set-image-blocker{blank}</link> }
6660 / # ALL sites</screen>
6666 <!-- ~ End section ~ -->
6670 <!-- ~ End section ~ -->
6672 <!-- ~~~~~~~~ New section Header ~~~~~~~~~ -->
6674 <sect1 id="filter-file">
6675 <title>Filter Files</title>
6678 On-the-fly text substitutions need
6679 to be defined in a <quote>filter file</quote>. Once defined, they
6680 can then be invoked as an <quote>action</quote>.
6684 &my-app; supports three different pcrs-based filter actions:
6685 <literal><link linkend="filter">filter</link></literal> to
6686 rewrite the content that is send to the client,
6687 <literal><link linkend="client-header-filter">client-header-filter</link></literal>
6688 to rewrite headers that are send by the client, and
6689 <literal><link linkend="server-header-filter">server-header-filter</link></literal>
6690 to rewrite headers that are send by the server.
6694 &my-app; also supports two tagger actions:
6695 <literal><link linkend="client-header-tagger">client-header-tagger</link></literal>
6697 <literal><link linkend="server-header-tagger">server-header-tagger</link></literal>.
6698 Taggers and filters use the same syntax in the filter files, the difference
6699 is that taggers don't modify the text they are filtering, but use a rewritten
6700 version of the filtered text as tag. The tags can then be used to change the
6701 applying actions through sections with <link linkend="tag-pattern">tag-patterns</link>.
6705 Finally &my-app; supports the
6706 <literal><link linkend="external-filter">external-filter</link></literal> action
6707 to enable <literal><link linkend="external-filter-syntax">external filters</link></literal>
6708 written in proper programming languages.
6713 Multiple filter files can be defined through the <literal> <link
6714 linkend="filterfile">filterfile</link></literal> config directive. The filters
6715 as supplied by the developers are located in
6716 <filename>default.filter</filename>. It is recommended that any locally
6717 defined or modified filters go in a separately defined file such as
6718 <filename>user.filter</filename>.
6722 Common tasks for content filters are to eliminate common annoyances in
6723 HTML and JavaScript, such as pop-up windows,
6724 exit consoles, crippled windows without navigation tools, the
6725 infamous <BLINK> tag etc, to suppress images with certain
6726 width and height attributes (standard banner sizes or web-bugs),
6727 or just to have fun.
6731 Enabled content filters are applied to any content whose
6732 <quote>Content Type</quote> header is recognised as a sign
6733 of text-based content, with the exception of <literal>text/plain</literal>.
6734 Use the <link linkend="FORCE-TEXT-MODE">force-text-mode</link> action
6735 to also filter other content.
6739 Substitutions are made at the source level, so if you want to <quote>roll
6740 your own</quote> filters, you should first be familiar with HTML syntax,
6741 and, of course, regular expressions.
6745 Just like the <link linkend="actions-file">actions files</link>, the
6746 filter file is organized in sections, which are called <emphasis>filters</emphasis>
6747 here. Each filter consists of a heading line, that starts with one of the
6748 <emphasis>keywords</emphasis> <literal>FILTER:</literal>,
6749 <literal>CLIENT-HEADER-FILTER:</literal> or <literal>SERVER-HEADER-FILTER:</literal>
6750 followed by the filter's <emphasis>name</emphasis>, and a short (one line)
6751 <emphasis>description</emphasis> of what it does. Below that line
6752 come the <emphasis>jobs</emphasis>, i.e. lines that define the actual
6753 text substitutions. By convention, the name of a filter
6754 should describe what the filter <emphasis>eliminates</emphasis>. The
6755 comment is used in the <ulink url="http://config.privoxy.org/">web-based
6756 user interface</ulink>.
6760 Once a filter called <replaceable>name</replaceable> has been defined
6761 in the filter file, it can be invoked by using an action of the form
6762 +<literal><link linkend="filter">filter</link>{<replaceable>name</replaceable>}</literal>
6763 in any <link linkend="actions-file">actions file</link>.
6767 Filter definitions start with a header line that contains the filter
6768 type, the filter name and the filter description.
6769 A content filter header line for a filter called <quote>foo</quote> could look
6774 <screen>FILTER: foo Replace all "foo" with "bar"</screen>
6778 Below that line, and up to the next header line, come the jobs that
6779 define what text replacements the filter executes. They are specified
6780 in a syntax that imitates <ulink url="http://www.perl.org/">Perl</ulink>'s
6781 <literal>s///</literal> operator. If you are familiar with Perl, you
6782 will find this to be quite intuitive, and may want to look at the
6783 PCRS documentation for the subtle differences to Perl behaviour.
6787 Most notably, the non-standard option letter <literal>U</literal> is supported,
6788 which turns the default to ungreedy matching (add <literal>?</literal> to
6789 quantifiers to turn them greedy again).
6793 The non-standard option letter <literal>D</literal> (dynamic) allows
6794 to use the variables $host, $origin (the IP address the request came from),
6795 $path, $url and $listen-address (the address on which Privoxy accepted the
6796 client request. Example: 127.0.0.1:8118).
6797 They will be replaced with the value they refer to before the filter
6802 Note that '$' is a bad choice for a delimiter in a dynamic filter as you
6803 might end up with unintended variables if you use a variable name
6804 directly after the delimiter. Variables will be resolved without
6805 escaping anything, therefore you also have to be careful not to chose
6806 delimiters that appear in the replacement text. For example '<' should
6807 be save, while '?' will sooner or later cause conflicts with $url.
6811 The non-standard option letter <literal>T</literal> (trivial) prevents
6812 parsing for backreferences in the substitute. Use it if you want to include
6813 text like '$&' in your substitute without quoting.
6818 <ulink url="http://en.wikipedia.org/wiki/Regular_expressions"><quote>Regular
6819 Expressions</quote></ulink>, you might want to take a look at
6820 the <link linkend="regex">Appendix on regular expressions</link>, and
6821 see the <ulink url="http://perldoc.perl.org/perlre.html">Perl
6823 <ulink url="http://perldoc.perl.org/perlop.html">the
6824 <literal>s///</literal> operator's syntax</ulink> and <ulink
6825 url="http://perldoc.perl.org/perlre.html">Perl-style regular
6826 expressions</ulink> in general.
6827 The below examples might also help to get you started.
6831 <!-- ~~~~~~~~ New section Header ~~~~~~~~~ -->
6833 <sect2 id="filter-file-tut"><title>Filter File Tutorial</title>
6835 Now, let's complete our <quote>foo</quote> content filter. We have already defined
6836 the heading, but the jobs are still missing. Since all it does is to replace
6837 <quote>foo</quote> with <quote>bar</quote>, there is only one (trivial) job
6842 <screen>s/foo/bar/</screen>
6846 But wait! Didn't the comment say that <emphasis>all</emphasis> occurrences
6847 of <quote>foo</quote> should be replaced? Our current job will only take
6848 care of the first <quote>foo</quote> on each page. For global substitution,
6849 we'll need to add the <literal>g</literal> option:
6853 <screen>s/foo/bar/g</screen>
6857 Our complete filter now looks like this:
6860 <screen>FILTER: foo Replace all "foo" with "bar"
6861 s/foo/bar/g</screen>
6865 Let's look at some real filters for more interesting examples. Here you see
6866 a filter that protects against some common annoyances that arise from JavaScript
6867 abuse. Let's look at its jobs one after the other:
6873 FILTER: js-annoyances Get rid of particularly annoying JavaScript abuse
6875 # Get rid of JavaScript referrer tracking. Test page: http://www.randomoddness.com/untitled.htm
6877 s|(<script.*)document\.referrer(.*</script>)|$1"Not Your Business!"$2|Usg</screen>
6881 Following the header line and a comment, you see the job. Note that it uses
6882 <literal>|</literal> as the delimiter instead of <literal>/</literal>, because
6883 the pattern contains a forward slash, which would otherwise have to be escaped
6884 by a backslash (<literal>\</literal>).
6888 Now, let's examine the pattern: it starts with the text <literal><script.*</literal>
6889 enclosed in parentheses. Since the dot matches any character, and <literal>*</literal>
6890 means: <quote>Match an arbitrary number of the element left of myself</quote>, this
6891 matches <quote><script</quote>, followed by <emphasis>any</emphasis> text, i.e.
6892 it matches the whole page, from the start of the first <script> tag.
6896 That's more than we want, but the pattern continues: <literal>document\.referrer</literal>
6897 matches only the exact string <quote>document.referrer</quote>. The dot needed to
6898 be <emphasis>escaped</emphasis>, i.e. preceded by a backslash, to take away its
6899 special meaning as a joker, and make it just a regular dot. So far, the meaning is:
6900 Match from the start of the first <script> tag in a the page, up to, and including,
6901 the text <quote>document.referrer</quote>, if <emphasis>both</emphasis> are present
6902 in the page (and appear in that order).
6906 But there's still more pattern to go. The next element, again enclosed in parentheses,
6907 is <literal>.*</script></literal>. You already know what <literal>.*</literal>
6908 means, so the whole pattern translates to: Match from the start of the first <script>
6909 tag in a page to the end of the last <script> tag, provided that the text
6910 <quote>document.referrer</quote> appears somewhere in between.
6914 This is still not the whole story, since we have ignored the options and the parentheses:
6915 The portions of the page matched by sub-patterns that are enclosed in parentheses, will be
6916 remembered and be available through the variables <literal>$1, $2, ...</literal> in
6917 the substitute. The <literal>U</literal> option switches to ungreedy matching, which means
6918 that the first <literal>.*</literal> in the pattern will only <quote>eat up</quote> all
6919 text in between <quote><script</quote> and the <emphasis>first</emphasis> occurrence
6920 of <quote>document.referrer</quote>, and that the second <literal>.*</literal> will
6921 only span the text up to the <emphasis>first</emphasis> <quote></script></quote>
6922 tag. Furthermore, the <literal>s</literal> option says that the match may span
6923 multiple lines in the page, and the <literal>g</literal> option again means that the
6924 substitution is global.
6928 So, to summarize, the pattern means: Match all scripts that contain the text
6929 <quote>document.referrer</quote>. Remember the parts of the script from
6930 (and including) the start tag up to (and excluding) the string
6931 <quote>document.referrer</quote> as <literal>$1</literal>, and the part following
6932 that string, up to and including the closing tag, as <literal>$2</literal>.
6936 Now the pattern is deciphered, but wasn't this about substituting things? So
6937 lets look at the substitute: <literal>$1"Not Your Business!"$2</literal> is
6938 easy to read: The text remembered as <literal>$1</literal>, followed by
6939 <literal>"Not Your Business!"</literal> (<emphasis>including</emphasis>
6940 the quotation marks!), followed by the text remembered as <literal>$2</literal>.
6941 This produces an exact copy of the original string, with the middle part
6942 (the <quote>document.referrer</quote>) replaced by <literal>"Not Your
6943 Business!"</literal>.
6947 The whole job now reads: Replace <quote>document.referrer</quote> by
6948 <literal>"Not Your Business!"</literal> wherever it appears inside a
6949 <script> tag. Note that this job won't break JavaScript syntax,
6950 since both the original and the replacement are syntactically valid
6951 string objects. The script just won't have access to the referrer
6952 information anymore.
6956 We'll show you two other jobs from the JavaScript taming department, but
6957 this time only point out the constructs of special interest:
6962 # The status bar is for displaying link targets, not pointless blahblah
6964 s/window\.status\s*=\s*(['"]).*?\1/dUmMy=1/ig</screen>
6968 <literal>\s</literal> stands for whitespace characters (space, tab, newline,
6969 carriage return, form feed), so that <literal>\s*</literal> means: <quote>zero
6970 or more whitespace</quote>. The <literal>?</literal> in <literal>.*?</literal>
6971 makes this matching of arbitrary text ungreedy. (Note that the <literal>U</literal>
6972 option is not set). The <literal>['"]</literal> construct means: <quote>a single
6973 <emphasis>or</emphasis> a double quote</quote>. Finally, <literal>\1</literal> is
6974 a back-reference to the first parenthesis just like <literal>$1</literal> above,
6975 with the difference that in the <emphasis>pattern</emphasis>, a backslash indicates
6976 a back-reference, whereas in the <emphasis>substitute</emphasis>, it's the dollar.
6980 So what does this job do? It replaces assignments of single- or double-quoted
6981 strings to the <quote>window.status</quote> object with a dummy assignment
6982 (using a variable name that is hopefully odd enough not to conflict with
6983 real variables in scripts). Thus, it catches many cases where e.g. pointless
6984 descriptions are displayed in the status bar instead of the link target when
6985 you move your mouse over links.
6990 # Kill OnUnload popups. Yummy. Test: http://www.zdnet.com/zdsubs/yahoo/tree/yfs.html
6992 s/(<body [^>]*)onunload(.*>)/$1never$2/iU</screen>
6997 <ulink url="http://www.w3.org/TR/2000/REC-DOM-Level-2-Events-20001113/events.html#Events-eventgroupings-htmlevents">OnUnload
6998 event binding</ulink> in the HTML DOM was a <emphasis>CRIME</emphasis>.
6999 When I close a browser window, I want it to close and die. Basta.
7000 This job replaces the <quote>onunload</quote> attribute in
7001 <quote><body></quote> tags with the dummy word <literal>never</literal>.
7002 Note that the <literal>i</literal> option makes the pattern matching
7003 case-insensitive. Also note that ungreedy matching alone doesn't always guarantee
7004 a minimal match: In the first parenthesis, we had to use <literal>[^>]*</literal>
7005 instead of <literal>.*</literal> to prevent the match from exceeding the
7006 <body> tag if it doesn't contain <quote>OnUnload</quote>, but the page's
7011 The last example is from the fun department:
7016 FILTER: fun Fun text replacements
7018 # Spice the daily news:
7020 s/microsoft(?!\.com)/MicroSuck/ig</screen>
7024 Note the <literal>(?!\.com)</literal> part (a so-called negative lookahead)
7025 in the job's pattern, which means: Don't match, if the string
7026 <quote>.com</quote> appears directly following <quote>microsoft</quote>
7027 in the page. This prevents links to microsoft.com from being trashed, while
7028 still replacing the word everywhere else.
7033 # Buzzword Bingo (example for extended regex syntax)
7035 s* industry[ -]leading \
7037 | customer[ -]focused \
7038 | market[ -]driven \
7039 | award[ -]winning # Comments are OK, too! \
7040 | high[ -]performance \
7041 | solutions[ -]based \
7045 *<font color="red"><b>BINGO!</b></font> \
7050 The <literal>x</literal> option in this job turns on extended syntax, and allows for
7051 e.g. the liberal use of (non-interpreted!) whitespace for nicer formatting.
7059 <!-- ~~~~~~~~ New section Header ~~~~~~~~~ -->
7061 <sect2 id="predefined-filters"><title>The Pre-defined Filters</title>
7065 Note each filter is also listed in the +filter action section above. Please
7066 keep these listings in sync.
7071 The distribution <filename>default.filter</filename> file contains a selection of
7072 pre-defined filters for your convenience:
7077 <term><emphasis>js-annoyances</emphasis></term>
7080 The purpose of this filter is to get rid of particularly annoying JavaScript abuse.
7085 replaces JavaScript references to the browser's referrer information
7086 with the string "Not Your Business!". This compliments the <literal><link
7087 linkend="hide-referrer">hide-referrer</link></literal> action on the content level.
7092 removes the bindings to the DOM's
7093 <ulink url="http://www.w3.org/TR/2000/REC-DOM-Level-2-Events-20001113/events.html#Events-eventgroupings-htmlevents">unload
7094 event</ulink> which we feel has no right to exist and is responsible for most <quote>exit consoles</quote>, i.e.
7095 nasty windows that pop up when you close another one.
7100 removes code that causes new windows to be opened with undesired properties, such as being
7101 full-screen, non-resizeable, without location, status or menu bar etc.
7107 Use with caution. This is an aggressive filter, and can break sites that
7108 rely heavily on JavaScript.
7114 <term><emphasis>js-events</emphasis></term>
7117 This is a very radical measure. It removes virtually all JavaScript event bindings, which
7118 means that scripts can not react to user actions such as mouse movements or clicks, window
7119 resizing etc, anymore. Use with caution!
7122 We <emphasis>strongly discourage</emphasis> using this filter as a default since it breaks
7123 many legitimate scripts. It is meant for use only on extra-nasty sites (should you really
7130 <term><emphasis>html-annoyances</emphasis></term>
7133 This filter will undo many common instances of HTML based abuse.
7136 The <literal>BLINK</literal> and <literal>MARQUEE</literal> tags
7137 are neutralized (yeah baby!), and browser windows will be created as
7138 resizeable (as of course they should be!), and will have location,
7139 scroll and menu bars -- even if specified otherwise.
7145 <term><emphasis>content-cookies</emphasis></term>
7148 Most cookies are set in the HTTP dialog, where they can be intercepted
7150 <literal><link linkend="crunch-incoming-cookies">crunch-incoming-cookies</link></literal>
7151 and <literal><link linkend="crunch-outgoing-cookies">crunch-outgoing-cookies</link></literal>
7152 actions. But web sites increasingly make use of HTML meta tags and JavaScript
7153 to sneak cookies to the browser on the content level.
7156 This filter disables most HTML and JavaScript code that reads or sets
7157 cookies. It cannot detect all clever uses of these types of code, so it
7158 should not be relied on as an absolute fix. Use it wherever you would also
7159 use the cookie crunch actions.
7165 <term><emphasis>refresh-tags</emphasis></term>
7168 Disable any refresh tags if the interval is greater than nine seconds (so
7169 that redirections done via refresh tags are not destroyed). This is useful
7170 for dial-on-demand setups, or for those who find this HTML feature
7177 <term><emphasis>unsolicited-popups</emphasis></term>
7180 This filter attempts to prevent only <quote>unsolicited</quote> pop-up
7181 windows from opening, yet still allow pop-up windows that the user
7182 has explicitly chosen to open. It was added in version 3.0.1,
7183 as an improvement over earlier such filters.
7186 Technical note: The filter works by redefining the window.open JavaScript
7187 function to a dummy function, <literal>PrivoxyWindowOpen()</literal>,
7188 during the loading and rendering phase of each HTML page access, and
7189 restoring the function afterward.
7192 This is recommended only for browsers that cannot perform this function
7193 reliably themselves. And be aware that some sites require such windows
7194 in order to function normally. Use with caution.
7200 <term><emphasis>all-popups</emphasis></term>
7203 Attempt to prevent <emphasis>all</emphasis> pop-up windows from opening.
7204 Note this should be used with even more discretion than the above, since
7205 it is more likely to break some sites that require pop-ups for normal
7206 usage. Use with caution.
7212 <term><emphasis>img-reorder</emphasis></term>
7215 This is a helper filter that has no value if used alone. It makes the
7216 <literal>banners-by-size</literal> and <literal>banners-by-link</literal>
7217 (see below) filters more effective and should be enabled together with them.
7223 <term><emphasis>banners-by-size</emphasis></term>
7226 This filter removes image tags purely based on what size they are. Fortunately
7227 for us, many ads and banner images tend to conform to certain standardized
7228 sizes, which makes this filter quite effective for ad stripping purposes.
7231 Occasionally this filter will cause false positives on images that are not ads,
7232 but just happen to be of one of the standard banner sizes.
7235 Recommended only for those who require extreme ad blocking. The default
7236 block rules should catch 95+% of all ads <emphasis>without</emphasis> this filter enabled.
7242 <term><emphasis>banners-by-link</emphasis></term>
7245 This is an experimental filter that attempts to kill any banners if
7246 their URLs seem to point to known or suspected click trackers. It is currently
7247 not of much value and is not recommended for use by default.
7253 <term><emphasis>webbugs</emphasis></term>
7256 Webbugs are small, invisible images (technically 1X1 GIF images), that
7257 are used to track users across websites, and collect information on them.
7258 As an HTML page is loaded by the browser, an embedded image tag causes the
7259 browser to contact a third-party site, disclosing the tracking information
7260 through the requested URL and/or cookies for that third-party domain, without
7261 the user ever becoming aware of the interaction with the third-party site.
7262 HTML-ized spam also uses a similar technique to verify email addresses.
7265 This filter removes the HTML code that loads such <quote>webbugs</quote>.
7271 <term><emphasis>tiny-textforms</emphasis></term>
7274 A rather special-purpose filter that can be used to enlarge textareas (those
7275 multi-line text boxes in web forms) and turn off hard word wrap in them.
7276 It was written for the sourceforge.net tracker system where such boxes are
7277 a nuisance, but it can be handy on other sites, too.
7280 It is not recommended to use this filter as a default.
7286 <term><emphasis>jumping-windows</emphasis></term>
7289 Many consider windows that move, or resize themselves to be abusive. This filter
7290 neutralizes the related JavaScript code. Note that some sites might not display
7291 or behave as intended when using this filter. Use with caution.
7297 <term><emphasis>frameset-borders</emphasis></term>
7300 Some web designers seem to assume that everyone in the world will view their
7301 web sites using the same browser brand and version, screen resolution etc,
7302 because only that assumption could explain why they'd use static frame sizes,
7303 yet prevent their frames from being resized by the user, should they be too
7304 small to show their whole content.
7307 This filter removes the related HTML code. It should only be applied to sites
7314 <term><emphasis>demoronizer</emphasis></term>
7317 Many Microsoft products that generate HTML use non-standard extensions (read:
7318 violations) of the ISO 8859-1 aka Latin-1 character set. This can cause those
7319 HTML documents to display with errors on standard-compliant platforms.
7322 This filter translates the MS-only characters into Latin-1 equivalents.
7323 It is not necessary when using MS products, and will cause corruption of
7324 all documents that use 8-bit character sets other than Latin-1. It's mostly
7325 worthwhile for Europeans on non-MS platforms, if weird garbage characters
7326 sometimes appear on some pages, or user agents that don't correct for this on
7329 My version of Mozilla (ancient) shows litte square boxes for quote
7330 characters, and apostrophes on moronized pages. So many pages have this, I
7331 can read them fine now. HB 08/27/06
7338 <term><emphasis>shockwave-flash</emphasis></term>
7341 A filter for shockwave haters. As the name suggests, this filter strips code
7342 out of web pages that is used to embed shockwave flash objects.
7350 <term><emphasis>quicktime-kioskmode</emphasis></term>
7353 Change HTML code that embeds Quicktime objects so that kioskmode, which
7354 prevents saving, is disabled.
7360 <term><emphasis>fun</emphasis></term>
7363 Text replacements for subversive browsing fun. Make fun of your favorite
7364 Monopolist or play buzzword bingo.
7370 <term><emphasis>crude-parental</emphasis></term>
7373 A demonstration-only filter that shows how <application>Privoxy</application>
7374 can be used to delete web content on a keyword basis.
7380 <term><emphasis>ie-exploits</emphasis></term>
7383 An experimental collection of text replacements to disable malicious HTML and JavaScript
7384 code that exploits known security holes in Internet Explorer.
7387 Presently, it only protects against Nimda and a cross-site scripting bug, and
7388 would need active maintenance to provide more substantial protection.
7394 <term><emphasis>site-specifics</emphasis></term>
7397 Some web sites have very specific problems, the cure for which doesn't apply
7398 anywhere else, or could even cause damage on other sites.
7401 This is a collection of such site-specific cures which should only be applied
7402 to the sites they were intended for, which is what the supplied
7403 <filename>default.action</filename> file does. Users shouldn't need to change
7404 anything regarding this filter.
7410 <term><emphasis>google</emphasis></term>
7413 A CSS based block for Google text ads. Also removes a width limitation
7414 and the toolbar advertisement.
7420 <term><emphasis>yahoo</emphasis></term>
7423 Another CSS based block, this time for Yahoo text ads. And removes
7424 a width limitation as well.
7430 <term><emphasis>msn</emphasis></term>
7433 Another CSS based block, this time for MSN text ads. And removes
7434 tracking URLs, as well as a width limitation.
7440 <term><emphasis>blogspot</emphasis></term>
7443 Cleans up some Blogspot blogs. Read the fine print before using this one!
7446 This filter also intentionally removes some navigation stuff and sets the
7447 page width to 100%. As a result, some rounded <quote>corners</quote> would
7448 appear to early or not at all and as fixing this would require a browser
7449 that understands background-size (CSS3), they are removed instead.
7455 <term><emphasis>xml-to-html</emphasis></term>
7458 Server-header filter to change the Content-Type from xml to html.
7464 <term><emphasis>html-to-xml</emphasis></term>
7467 Server-header filter to change the Content-Type from html to xml.
7473 <term><emphasis>no-ping</emphasis></term>
7476 Removes the non-standard <literal>ping</literal> attribute from
7477 anchor and area HTML tags.
7483 <term><emphasis>hide-tor-exit-notation</emphasis></term>
7486 Client-header filter to remove the <command>Tor</command> exit node notation
7487 found in Host and Referer headers.
7490 If &my-app; and <command>Tor</command> are chained and &my-app;
7491 is configured to use socks4a, one can use <quote>http://www.example.org.foobar.exit/</quote>
7492 to access the host <quote>www.example.org</quote> through the
7493 <command>Tor</command> exit node <quote>foobar</quote>.
7496 As the HTTP client isn't aware of this notation, it treats the
7497 whole string <quote>www.example.org.foobar.exit</quote> as host and uses it
7498 for the <quote>Host</quote> and <quote>Referer</quote> headers. From the
7499 server's point of view the resulting headers are invalid and can cause problems.
7502 An invalid <quote>Referer</quote> header can trigger <quote>hot-linking</quote>
7503 protections, an invalid <quote>Host</quote> header will make it impossible for
7504 the server to find the right vhost (several domains hosted on the same IP address).
7507 This client-header filter removes the <quote>foo.exit</quote> part in those headers
7508 to prevent the mentioned problems. Note that it only modifies
7509 the HTTP headers, it doesn't make it impossible for the server
7510 to detect your <command>Tor</command> exit node based on the IP address
7511 the request is coming from.
7518 <term><emphasis> </emphasis></term>
7531 <!-- ~~~~~~~~ New section Header ~~~~~~~~~ -->
7532 <sect2 id="external-filter-syntax"><title>External filter syntax</title>
7534 External filters are scripts or programs that can modify the content in
7535 case common <literal><link linkend="filter">filters</link></literal>
7536 aren't powerful enough.
7539 External filters can be written in any language the platform &my-app; runs
7543 They are controlled with the
7544 <literal><link linkend="external-filter">external-filter</link></literal> action
7545 and have to be defined in the <literal><link linkend="filterfile">filterfile</link></literal>
7549 The header looks like any other filter, but instead of pcrs jobs, external
7550 filters contain a single job which can be a program or a shell script (which
7551 may call other scripts or programs).
7554 External filters read the content from STDIN and write the rewritten
7556 The environment variables PRIVOXY_URL, PRIVOXY_PATH, PRIVOXY_HOST,
7557 PRIVOXY_ORIGIN, PRIVOXY_LISTEN_ADDRESS can be used to get some details
7558 about the client request.
7561 &my-app; will temporary store the content to filter in the
7562 <literal><link linkend="temporary-directory">temporary-directory</link></literal>.
7566 EXTERNAL-FILTER: cat Pointless example filter that doesn't actually modify the content
7569 # Incorrect reimplementation of the filter above in POSIX shell.
7571 # Note that it's a single job that spans multiple lines, the line
7572 # breaks are not passed to the shell, thus the semicolons are required.
7574 # If the script isn't trivial, it is recommended to put it into an external file.
7576 # In general, writing external filters entirely in POSIX shell is not
7577 # considered a good idea.
7578 EXTERNAL-FILTER: cat2 Pointless example filter that despite its name may actually modify the content
7584 EXTERNAL-FILTER: rotate-image Rotate an image by 180 degree. Test filter with limited value.
7585 /usr/local/bin/convert - -rotate 180 -
7587 EXTERNAL-FILTER: citation-needed Adds a "[citation needed]" tag to an image. The coordinates may need adjustment.
7588 /usr/local/bin/convert - -pointsize 16 -fill white -annotate +17+418 "[citation needed]" -
7594 Currently external filters are executed with &my-app;'s privileges!
7595 Only use external filters you understand and trust.
7599 External filters are experimental and the syntax may change in the future.
7605 <!-- ~ End section ~ -->
7609 <!-- ~~~~~ New section ~~~~~ -->
7611 <sect1 id="templates">
7612 <title>Privoxy's Template Files</title>
7614 All <application>Privoxy</application> built-in pages, i.e. error pages such as the
7615 <ulink url="http://show-the-404-error.page"><quote>404 - No Such Domain</quote>
7616 error page</ulink>, the <ulink
7617 url="http://ads.bannerserver.example.com/nasty-ads/sponsor.html"><quote>BLOCKED</quote>
7619 and all pages of its <ulink url="http://config.privoxy.org/">web-based
7620 user interface</ulink>, are generated from <emphasis>templates</emphasis>.
7621 (<application>Privoxy</application> must be running for the above links to work as
7626 These templates are stored in a subdirectory of the <link linkend="confdir">configuration
7627 directory</link> called <filename>templates</filename>. On Unixish platforms,
7629 <ulink url="file:///etc/privoxy/templates/"><filename>/etc/privoxy/templates/</filename></ulink>.
7633 The templates are basically normal HTML files, but with place-holders (called symbols
7634 or exports), which <application>Privoxy</application> fills at run time. It
7635 is possible to edit the templates with a normal text editor, should you want
7636 to customize them. (<emphasis>Not recommended for the casual
7637 user</emphasis>). Should you create your own custom templates, you should use
7638 the <filename>config</filename> setting <link linkend="templdir">templdir</link>
7639 to specify an alternate location, so your templates do not get overwritten
7643 Note that just like in configuration files, lines starting
7644 with <literal>#</literal> are ignored when the templates are filled in.
7648 The place-holders are of the form <literal>@name@</literal>, and you will
7649 find a list of available symbols, which vary from template to template,
7650 in the comments at the start of each file. Note that these comments are not
7651 always accurate, and that it's probably best to look at the existing HTML
7652 code to find out which symbols are supported and what they are filled in with.
7656 A special application of this substitution mechanism is to make whole
7657 blocks of HTML code disappear when a specific symbol is set. We use this
7658 for many purposes, one of them being to include the beta warning in all
7659 our user interface (CGI) pages when <application>Privoxy</application>
7660 is in an alpha or beta development stage:
7665 <!-- @if-unstable-start -->
7667 ... beta warning HTML code goes here ...
7669 <!-- if-unstable-end@ --></screen>
7673 If the "unstable" symbol is set, everything in between and including
7674 <literal>@if-unstable-start</literal> and <literal>if-unstable-end@</literal>
7675 will disappear, leaving nothing but an empty comment:
7679 <screen><!-- --></screen>
7683 There's also an if-then-else construct and an <literal>#include</literal>
7684 mechanism, but you'll sure find out if you are inclined to edit the
7689 All templates refer to a style located at
7690 <ulink url="http://config.privoxy.org/send-stylesheet"><literal>http://config.privoxy.org/send-stylesheet</literal></ulink>.
7691 This is, of course, locally served by <application>Privoxy</application>
7692 and the source for it can be found and edited in the
7693 <filename>cgi-style.css</filename> template.
7698 <!-- ~ End section ~ -->
7702 <!-- ~~~~~ New section ~~~~~ -->
7704 <sect1 id="contact"><title>Contacting the Developers, Bug Reporting and Feature
7707 <!-- Include contacting.sgml boilerplate: -->
7709 <!-- end boilerplate -->
7713 <!-- ~ End section ~ -->
7716 <!-- ~~~~~ New section ~~~~~ -->
7717 <sect1 id="copyright"><title>Privoxy Copyright, License and History</title>
7719 <!-- Include copyright.sgml: -->
7721 <!-- end copyright -->
7724 <application>Privoxy</application> is free software; you can
7725 redistribute it and/or modify it under the terms of the
7726 <citetitle>GNU General Public License</citetitle>, version 2,
7727 as published by the Free Software Foundation and included in
7731 <!-- ~~~~~ New section ~~~~~ -->
7732 <sect2 id="license"><title>License</title>
7734 <screen><![ RCDATA [ &GPLv2; ]]></screen>
7738 <!-- ~ End section ~ -->
7741 <!-- ~~~~~ New section ~~~~~ -->
7743 <sect2 id="history"><title>History</title>
7744 <!-- Include history.sgml: -->
7746 <!-- end history -->
7749 <sect2 id="authors"><title>Authors</title>
7750 <!-- Include p-authors.sgml: -->
7752 <!-- end authors -->
7757 <!-- ~ End section ~ -->
7760 <!-- ~~~~~ New section ~~~~~ -->
7761 <sect1 id="seealso"><title>See Also</title>
7762 <!-- Include seealso.sgml: -->
7764 <!-- end seealso -->
7769 <!-- ~~~~~ New section ~~~~~ -->
7770 <sect1 id="appendix"><title>Appendix</title>
7773 <!-- ~~~~~ New section ~~~~~ -->
7775 <title>Regular Expressions</title>
7777 <application>Privoxy</application> uses Perl-style <quote>regular
7778 expressions</quote> in its <link linkend="actions-file">actions
7779 files</link> and <link linkend="filter-file">filter file</link>,
7780 through the <ulink url="http://www.pcre.org/">PCRE</ulink> and
7783 <ulink url="http://www.oesterhelt.org/pcrs/">PCRS</ulink> libraries.
7785 <application>PCRS</application> libraries.
7789 If you are reading this, you probably don't understand what <quote>regular
7790 expressions</quote> are, or what they can do. So this will be a very brief
7791 introduction only. A full explanation would require a <ulink
7792 url="http://www.oreilly.com/catalog/regex/">book</ulink> ;-)
7796 Regular expressions provide a language to describe patterns that can be
7797 run against strings of characters (letter, numbers, etc), to see if they
7798 match the string or not. The patterns are themselves (sometimes complex)
7799 strings of literal characters, combined with wild-cards, and other special
7800 characters, called meta-characters. The <quote>meta-characters</quote> have
7801 special meanings and are used to build complex patterns to be matched against.
7802 Perl Compatible Regular Expressions are an especially convenient
7803 <quote>dialect</quote> of the regular expression language.
7807 To make a simple analogy, we do something similar when we use wild-card
7808 characters when listing files with the <command>dir</command> command in DOS.
7809 <literal>*.*</literal> matches all filenames. The <quote>special</quote>
7810 character here is the asterisk which matches any and all characters. We can be
7811 more specific and use <literal>?</literal> to match just individual
7812 characters. So <quote>dir file?.text</quote> would match
7813 <quote>file1.txt</quote>, <quote>file2.txt</quote>, etc. We are pattern
7814 matching, using a similar technique to <quote>regular expressions</quote>!
7818 Regular expressions do essentially the same thing, but are much, much more
7819 powerful. There are many more <quote>special characters</quote> and ways of
7820 building complex patterns however. Let's look at a few of the common ones,
7821 and then some examples:
7826 <emphasis>.</emphasis> - Matches any single character, e.g. <quote>a</quote>,
7827 <quote>A</quote>, <quote>4</quote>, <quote>:</quote>, or <quote>@</quote>.
7829 </simplelist></para>
7833 <emphasis>?</emphasis> - The preceding character or expression is matched ZERO or ONE
7836 </simplelist></para>
7840 <emphasis>+</emphasis> - The preceding character or expression is matched ONE or MORE
7843 </simplelist></para>
7847 <emphasis>*</emphasis> - The preceding character or expression is matched ZERO or MORE
7850 </simplelist></para>
7854 <emphasis>\</emphasis> - The <quote>escape</quote> character denotes that
7855 the following character should be taken literally. This is used where one of the
7856 special characters (e.g. <quote>.</quote>) needs to be taken literally and
7857 not as a special meta-character. Example: <quote>example\.com</quote>, makes
7858 sure the period is recognized only as a period (and not expanded to its
7859 meta-character meaning of any single character).
7861 </simplelist></para>
7865 <emphasis>[ ]</emphasis> - Characters enclosed in brackets will be matched if
7866 any of the enclosed characters are encountered. For instance, <quote>[0-9]</quote>
7867 matches any numeric digit (zero through nine). As an example, we can combine
7868 this with <quote>+</quote> to match any digit one of more times: <quote>[0-9]+</quote>.
7870 </simplelist></para>
7874 <emphasis>( )</emphasis> - parentheses are used to group a sub-expression,
7875 or multiple sub-expressions.
7877 </simplelist></para>
7881 <emphasis>|</emphasis> - The <quote>bar</quote> character works like an
7882 <quote>or</quote> conditional statement. A match is successful if the
7883 sub-expression on either side of <quote>|</quote> matches. As an example:
7884 <quote>/(this|that) example/</quote> uses grouping and the bar character
7885 and would match either <quote>this example</quote> or <quote>that
7886 example</quote>, and nothing else.
7888 </simplelist></para>
7891 These are just some of the ones you are likely to use when matching URLs with
7892 <application>Privoxy</application>, and is a long way from a definitive
7893 list. This is enough to get us started with a few simple examples which may
7894 be more illuminating:
7898 <emphasis><literal>/.*/banners/.*</literal></emphasis> - A simple example
7899 that uses the common combination of <quote>.</quote> and <quote>*</quote> to
7900 denote any character, zero or more times. In other words, any string at all.
7901 So we start with a literal forward slash, then our regular expression pattern
7902 (<quote>.*</quote>) another literal forward slash, the string
7903 <quote>banners</quote>, another forward slash, and lastly another
7904 <quote>.*</quote>. We are building
7905 a directory path here. This will match any file with the path that has a
7906 directory named <quote>banners</quote> in it. The <quote>.*</quote> matches
7907 any characters, and this could conceivably be more forward slashes, so it
7908 might expand into a much longer looking path. For example, this could match:
7909 <quote>/eye/hate/spammers/banners/annoy_me_please.gif</quote>, or just
7910 <quote>/banners/annoying.html</quote>, or almost an infinite number of other
7911 possible combinations, just so it has <quote>banners</quote> in the path
7916 And now something a little more complex:
7920 <emphasis><literal>/.*/adv((er)?ts?|ertis(ing|ements?))?/</literal></emphasis> -
7921 We have several literal forward slashes again (<quote>/</quote>), so we are
7922 building another expression that is a file path statement. We have another
7923 <quote>.*</quote>, so we are matching against any conceivable sub-path, just so
7924 it matches our expression. The only true literal that <emphasis>must
7925 match</emphasis> our pattern is <application>adv</application>, together with
7926 the forward slashes. What comes after the <quote>adv</quote> string is the
7931 Remember the <quote>?</quote> means the preceding expression (either a
7932 literal character or anything grouped with <quote>(...)</quote> in this case)
7933 can exist or not, since this means either zero or one match. So
7934 <quote>((er)?ts?|ertis(ing|ements?))</quote> is optional, as are the
7935 individual sub-expressions: <quote>(er)</quote>,
7936 <quote>(ing|ements?)</quote>, and the <quote>s</quote>. The <quote>|</quote>
7937 means <quote>or</quote>. We have two of those. For instance,
7938 <quote>(ing|ements?)</quote>, can expand to match either <quote>ing</quote>
7939 <emphasis>OR</emphasis> <quote>ements?</quote>. What is being done here, is an
7940 attempt at matching as many variations of <quote>advertisement</quote>, and
7941 similar, as possible. So this would expand to match just <quote>adv</quote>,
7942 or <quote>advert</quote>, or <quote>adverts</quote>, or
7943 <quote>advertising</quote>, or <quote>advertisement</quote>, or
7944 <quote>advertisements</quote>. You get the idea. But it would not match
7945 <quote>advertizements</quote> (with a <quote>z</quote>). We could fix that by
7946 changing our regular expression to:
7947 <quote>/.*/adv((er)?ts?|erti(s|z)(ing|ements?))?/</quote>, which would then match
7952 <emphasis><literal>/.*/advert[0-9]+\.(gif|jpe?g)</literal></emphasis> - Again
7953 another path statement with forward slashes. Anything in the square brackets
7954 <quote>[ ]</quote> can be matched. This is using <quote>0-9</quote> as a
7955 shorthand expression to mean any digit one through nine. It is the same as
7956 saying <quote>0123456789</quote>. So any digit matches. The <quote>+</quote>
7957 means one or more of the preceding expression must be included. The preceding
7958 expression here is what is in the square brackets -- in this case, any digit
7959 one through nine. Then, at the end, we have a grouping: <quote>(gif|jpe?g)</quote>.
7960 This includes a <quote>|</quote>, so this needs to match the expression on
7961 either side of that bar character also. A simple <quote>gif</quote> on one side, and the other
7962 side will in turn match either <quote>jpeg</quote> or <quote>jpg</quote>,
7963 since the <quote>?</quote> means the letter <quote>e</quote> is optional and
7964 can be matched once or not at all. So we are building an expression here to
7965 match image GIF or JPEG type image file. It must include the literal
7966 string <quote>advert</quote>, then one or more digits, and a <quote>.</quote>
7967 (which is now a literal, and not a special character, since it is escaped
7968 with <quote>\</quote>), and lastly either <quote>gif</quote>, or
7969 <quote>jpeg</quote>, or <quote>jpg</quote>. Some possible matches would
7970 include: <quote>//advert1.jpg</quote>,
7971 <quote>/nasty/ads/advert1234.gif</quote>,
7972 <quote>/banners/from/hell/advert99.jpg</quote>. It would not match
7973 <quote>advert1.gif</quote> (no leading slash), or
7974 <quote>/adverts232.jpg</quote> (the expression does not include an
7975 <quote>s</quote>), or <quote>/advert1.jsp</quote> (<quote>jsp</quote> is not
7976 in the expression anywhere).
7980 We are barely scratching the surface of regular expressions here so that you
7981 can understand the default <application>Privoxy</application>
7982 configuration files, and maybe use this knowledge to customize your own
7983 installation. There is much, much more that can be done with regular
7984 expressions. Now that you know enough to get started, you can learn more on
7989 More reading on Perl Compatible Regular expressions:
7990 <ulink url="http://perldoc.perl.org/perlre.html">http://perldoc.perl.org/perlre.html</ulink>
7994 For information on regular expression based substitutions and their applications
7995 in filters, please see the <link linkend="filter-file">filter file tutorial</link>
8000 <!-- ~ End section ~ -->
8003 <!-- ~~~~~ New section ~~~~~ -->
8004 <sect2 id="internal-pages">
8005 <title>Privoxy's Internal Pages</title>
8008 Since <application>Privoxy</application> proxies each requested
8009 web page, it is easy for <application>Privoxy</application> to
8010 trap certain special URLs. In this way, we can talk directly to
8011 <application>Privoxy</application>, and see how it is
8012 configured, see how our rules are being applied, change these
8013 rules and other configuration options, and even turn
8014 <application>Privoxy's</application> filtering off, all with
8020 The URLs listed below are the special ones that allow direct access
8021 to <application>Privoxy</application>. Of course,
8022 <application>Privoxy</application> must be running to access these. If
8023 not, you will get a friendly error message. Internet access is not
8036 <ulink url="http://config.privoxy.org/">http://config.privoxy.org/</ulink>
8040 There is a shortcut: <ulink url="http://p.p/">http://p.p/</ulink> (But it
8041 doesn't provide a fall-back to a real page, in case the request is not
8042 sent through <application>Privoxy</application>)
8048 Show information about the current configuration, including viewing and
8049 editing of actions files:
8053 <ulink url="http://config.privoxy.org/show-status">http://config.privoxy.org/show-status</ulink>
8060 Show the source code version numbers:
8064 <ulink url="http://config.privoxy.org/show-version">http://config.privoxy.org/show-version</ulink>
8071 Show the browser's request headers:
8075 <ulink url="http://config.privoxy.org/show-request">http://config.privoxy.org/show-request</ulink>
8082 Show which actions apply to a URL and why:
8086 <ulink url="http://config.privoxy.org/show-url-info">http://config.privoxy.org/show-url-info</ulink>
8093 Toggle Privoxy on or off. This feature can be turned off/on in the main
8094 <filename>config</filename> file. When toggled <quote>off</quote>, <quote>Privoxy</quote>
8095 continues to run, but only as a pass-through proxy, with no actions taking
8100 <ulink url="http://config.privoxy.org/toggle">http://config.privoxy.org/toggle</ulink>
8104 Short cuts. Turn off, then on:
8108 <ulink url="http://config.privoxy.org/toggle?set=disable">http://config.privoxy.org/toggle?set=disable</ulink>
8113 <ulink url="http://config.privoxy.org/toggle?set=enable">http://config.privoxy.org/toggle?set=enable</ulink>
8124 <!-- ~~~~~ New section ~~~~~ -->
8126 <title>Chain of Events</title>
8128 Let's take a quick look at how some of <application>Privoxy's</application>
8129 core features are triggered, and the ensuing sequence of events when a web
8130 page is requested by your browser:
8137 First, your web browser requests a web page. The browser knows to send
8138 the request to <application>Privoxy</application>, which will in turn,
8139 relay the request to the remote web server after passing the following
8145 <application>Privoxy</application> traps any request for its own internal CGI
8146 pages (e.g <ulink url="http://p.p/">http://p.p/</ulink>) and sends the CGI page back to the browser.
8151 Next, <application>Privoxy</application> checks to see if the URL
8153 linkend="BLOCK"><quote>+block</quote></link> patterns. If
8154 so, the URL is then blocked, and the remote web server will not be contacted.
8155 <link linkend="HANDLE-AS-IMAGE"><quote>+handle-as-image</quote></link>
8157 <link linkend="HANDLE-AS-EMPTY-DOCUMENT"><quote>+handle-as-empty-document</quote></link>
8158 are then checked, and if there is no match, an
8159 HTML <quote>BLOCKED</quote> page is sent back to the browser. Otherwise, if
8160 it does match, an image is returned for the former, and an empty text
8161 document for the latter. The type of image would depend on the setting of
8162 <link linkend="SET-IMAGE-BLOCKER"><quote>+set-image-blocker</quote></link>
8163 (blank, checkerboard pattern, or an HTTP redirect to an image elsewhere).
8168 Untrusted URLs are blocked. If URLs are being added to the
8169 <filename>trust</filename> file, then that is done.
8174 If the URL pattern matches the <link
8175 linkend="FAST-REDIRECTS"><quote>+fast-redirects</quote></link> action,
8176 it is then processed. Unwanted parts of the requested URL are stripped.
8181 Now the rest of the client browser's request headers are processed. If any
8182 of these match any of the relevant actions (e.g. <link
8183 linkend="HIDE-USER-AGENT"><quote>+hide-user-agent</quote></link>,
8184 etc.), headers are suppressed or forged as determined by these actions and
8190 Now the web server starts sending its response back (i.e. typically a web
8196 First, the server headers are read and processed to determine, among other
8197 things, the MIME type (document type) and encoding. The headers are then
8198 filtered as determined by the
8199 <link linkend="CRUNCH-INCOMING-COOKIES"><quote>+crunch-incoming-cookies</quote></link>,
8200 <link linkend="SESSION-COOKIES-ONLY"><quote>+session-cookies-only</quote></link>,
8201 and <link linkend="DOWNGRADE-HTTP-VERSION"><quote>+downgrade-http-version</quote></link>
8207 If any <link linkend="FILTER"><quote>+filter</quote></link> action
8209 linkend="DEANIMATE-GIFS"><quote>+deanimate-gifs</quote></link>
8210 action applies (and the document type fits the action), the rest of the page is
8211 read into memory (up to a configurable limit). Then the filter rules (from
8212 <filename>default.filter</filename> and any other filter files) are
8213 processed against the buffered content. Filters are applied in the order
8214 they are specified in one of the filter files. Animated GIFs, if present,
8215 are reduced to either the first or last frame, depending on the action
8216 setting.The entire page, which is now filtered, is then sent by
8217 <application>Privoxy</application> back to your browser.
8220 If neither a <link linkend="FILTER"><quote>+filter</quote></link> action
8222 linkend="DEANIMATE-GIFS"><quote>+deanimate-gifs</quote></link>
8223 matches, then <application>Privoxy</application> passes the raw data through
8224 to the client browser as it becomes available.
8229 As the browser receives the now (possibly filtered) page content, it
8230 reads and then requests any URLs that may be embedded within the page
8231 source, e.g. ad images, stylesheets, JavaScript, other HTML documents (e.g.
8232 frames), sounds, etc. For each of these objects, the browser issues a
8233 separate request (this is easily viewable in <application>Privoxy's</application>
8234 logs). And each such request is in turn processed just as above. Note that a
8235 complex web page will have many, many such embedded URLs. If these
8236 secondary requests are to a different server, then quite possibly a very
8237 differing set of actions is triggered.
8244 NOTE: This is somewhat of a simplistic overview of what happens with each URL
8245 request. For the sake of brevity and simplicity, we have focused on
8246 <application>Privoxy's</application> core features only.
8252 <!-- ~~~~~ New section ~~~~~ -->
8253 <sect2 id="actionsanat">
8254 <title>Troubleshooting: Anatomy of an Action</title>
8257 The way <application>Privoxy</application> applies
8258 <link linkend="ACTIONS">actions</link> and <link linkend="FILTER">filters</link>
8259 to any given URL can be complex, and not always so
8260 easy to understand what is happening. And sometimes we need to be able to
8261 <emphasis>see</emphasis> just what <application>Privoxy</application> is
8262 doing. Especially, if something <application>Privoxy</application> is doing
8263 is causing us a problem inadvertently. It can be a little daunting to look at
8264 the actions and filters files themselves, since they tend to be filled with
8265 <link linkend="regex">regular expressions</link> whose consequences are not
8270 One quick test to see if <application>Privoxy</application> is causing a problem
8271 or not, is to disable it temporarily. This should be the first troubleshooting
8272 step (be sure to flush caches afterward!). Looking at the
8273 logs is a good idea too. (Note that both the toggle feature and logging are
8274 enabled via <filename>config</filename> file settings, and may need to be
8275 turned <quote>on</quote>.)
8278 Another easy troubleshooting step to try is if you have done any
8279 customization of your installation, revert back to the installed
8280 defaults and see if that helps. There are times the developers get complaints
8281 about one thing or another, and the problem is more related to a customized
8282 configuration issue.
8286 <application>Privoxy</application> also provides the
8287 <ulink url="http://config.privoxy.org/show-url-info">http://config.privoxy.org/show-url-info</ulink>
8288 page that can show us very specifically how <application>actions</application>
8289 are being applied to any given URL. This is a big help for troubleshooting.
8293 First, enter one URL (or partial URL) at the prompt, and then
8294 <application>Privoxy</application> will tell us
8295 how the current configuration will handle it. This will not
8296 help with filtering effects (i.e. the <link
8297 linkend="FILTER"><quote>+filter</quote></link> action) from
8298 one of the filter files since this is handled very
8299 differently and not so easy to trap! It also will not tell you about any other
8300 URLs that may be embedded within the URL you are testing. For instance, images
8301 such as ads are expressed as URLs within the raw page source of HTML pages. So
8302 you will only get info for the actual URL that is pasted into the prompt area
8303 -- not any sub-URLs. If you want to know about embedded URLs like ads, you
8304 will have to dig those out of the HTML source. Use your browser's <quote>View
8305 Page Source</quote> option for this. Or right click on the ad, and grab the
8310 Let's try an example, <ulink url="http://google.com">google.com</ulink>,
8311 and look at it one section at a time in a sample configuration (your real
8312 configuration may vary):
8317 Matches for http://www.google.com:
8319 In file: default.action <guibutton>[ View ]</guibutton> <guibutton>[ Edit ]</guibutton>
8321 {+change-x-forwarded-for{block}
8322 +deanimate-gifs {last}
8323 +fast-redirects {check-decoded-url}
8324 +filter {refresh-tags}
8325 +filter {img-reorder}
8326 +filter {banners-by-size}
8328 +filter {jumping-windows}
8329 +filter {ie-exploits}
8330 +hide-from-header {block}
8331 +hide-referrer {forge}
8332 +session-cookies-only
8333 +set-image-blocker {pattern}
8336 { -session-cookies-only }
8342 In file: user.action <guibutton>[ View ]</guibutton> <guibutton>[ Edit ]</guibutton>
8343 (no matches in this file)
8348 This is telling us how we have defined our
8349 <link linkend="ACTIONS"><quote>actions</quote></link>, and
8350 which ones match for our test case, <quote>google.com</quote>.
8351 Displayed is all the actions that are available to us. Remember,
8352 the <literal>+</literal> sign denotes <quote>on</quote>. <literal>-</literal>
8353 denotes <quote>off</quote>. So some are <quote>on</quote> here, but many
8354 are <quote>off</quote>. Each example we try may provide a slightly different
8355 end result, depending on our configuration directives.
8359 is for our <filename>default.action</filename> file. The large, multi-line
8360 listing, is how the actions are set to match for all URLs, i.e. our default
8361 settings. If you look at your <quote>actions</quote> file, this would be the
8362 section just below the <quote>aliases</quote> section near the top. This
8363 will apply to all URLs as signified by the single forward slash at the end
8364 of the listing -- <quote> / </quote>.
8368 But we have defined additional actions that would be exceptions to these general
8369 rules, and then we list specific URLs (or patterns) that these exceptions
8370 would apply to. Last match wins. Just below this then are two explicit
8371 matches for <quote>.google.com</quote>. The first is negating our previous
8372 cookie setting, which was for <link
8373 linkend="SESSION-COOKIES-ONLY"><quote>+session-cookies-only</quote></link>
8374 (i.e. not persistent). So we will allow persistent cookies for google, at
8375 least that is how it is in this example. The second turns
8376 <emphasis>off</emphasis> any <link
8377 linkend="FAST-REDIRECTS"><quote>+fast-redirects</quote></link>
8378 action, allowing this to take place unmolested. Note that there is a leading
8379 dot here -- <quote>.google.com</quote>. This will match any hosts and
8380 sub-domains, in the google.com domain also, such as
8381 <quote>www.google.com</quote> or <quote>mail.google.com</quote>. But it would not
8382 match <quote>www.google.de</quote>! So, apparently, we have these two actions
8383 defined as exceptions to the general rules at the top somewhere in the lower
8384 part of our <filename>default.action</filename> file, and
8385 <quote>google.com</quote> is referenced somewhere in these latter sections.
8389 Then, for our <filename>user.action</filename> file, we again have no hits.
8390 So there is nothing google-specific that we might have added to our own, local
8391 configuration. If there was, those actions would over-rule any actions from
8392 previously processed files, such as <filename>default.action</filename>.
8393 <filename>user.action</filename> typically has the last word. This is the
8394 best place to put hard and fast exceptions,
8398 And finally we pull it all together in the bottom section and summarize how
8399 <application>Privoxy</application> is applying all its <quote>actions</quote>
8400 to <quote>google.com</quote>:
8411 +change-x-forwarded-for{block}
8412 -client-header-filter{hide-tor-exit-notation}
8413 -content-type-overwrite
8414 -crunch-client-header
8415 -crunch-if-none-match
8416 -crunch-incoming-cookies
8417 -crunch-outgoing-cookies
8418 -crunch-server-header
8419 +deanimate-gifs {last}
8420 -downgrade-http-version
8423 -filter {content-cookies}
8424 -filter {all-popups}
8425 -filter {banners-by-link}
8426 -filter {tiny-textforms}
8427 -filter {frameset-borders}
8428 -filter {demoronizer}
8429 -filter {shockwave-flash}
8430 -filter {quicktime-kioskmode}
8432 -filter {crude-parental}
8433 -filter {site-specifics}
8434 -filter {js-annoyances}
8435 -filter {html-annoyances}
8436 +filter {refresh-tags}
8437 -filter {unsolicited-popups}
8438 +filter {img-reorder}
8439 +filter {banners-by-size}
8441 +filter {jumping-windows}
8442 +filter {ie-exploits}
8449 -handle-as-empty-document
8451 -hide-accept-language
8452 -hide-content-disposition
8453 +hide-from-header {block}
8454 -hide-if-modified-since
8455 +hide-referrer {forge}
8458 -overwrite-last-modified
8459 -prevent-compression
8461 -server-header-filter{xml-to-html}
8462 -server-header-filter{html-to-xml}
8463 -session-cookies-only
8464 +set-image-blocker {pattern} </screen>
8468 Notice the only difference here to the previous listing, is to
8469 <quote>fast-redirects</quote> and <quote>session-cookies-only</quote>,
8470 which are activated specifically for this site in our configuration,
8471 and thus show in the <quote>Final Results</quote>.
8475 Now another example, <quote>ad.doubleclick.net</quote>:
8481 { +block{Domains starts with "ad"} }
8484 { +block{Domain contains "ad"} }
8487 { +block{Doubleclick banner server} +handle-as-image }
8488 .[a-vx-z]*.doubleclick.net
8493 We'll just show the interesting part here - the explicit matches. It is
8494 matched three different times. Two <quote>+block{}</quote> sections,
8495 and a <quote>+block{} +handle-as-image</quote>,
8496 which is the expanded form of one of our aliases that had been defined as:
8497 <quote>+block-as-image</quote>. (<link
8498 linkend="ALIASES"><quote>Aliases</quote></link> are defined in
8499 the first section of the actions file and typically used to combine more
8504 Any one of these would have done the trick and blocked this as an unwanted
8505 image. This is unnecessarily redundant since the last case effectively
8506 would also cover the first. No point in taking chances with these guys
8507 though ;-) Note that if you want an ad or obnoxious
8508 URL to be invisible, it should be defined as <quote>ad.doubleclick.net</quote>
8509 is done here -- as both a <link
8510 linkend="BLOCK"><quote>+block{}</quote></link>
8511 <emphasis>and</emphasis> an
8512 <link linkend="HANDLE-AS-IMAGE"><quote>+handle-as-image</quote></link>.
8513 The custom alias <quote><literal>+block-as-image</literal></quote> just
8514 simplifies the process and make it more readable.
8518 One last example. Let's try <quote>http://www.example.net/adsl/HOWTO/</quote>.
8519 This one is giving us problems. We are getting a blank page. Hmmm ...
8525 Matches for http://www.example.net/adsl/HOWTO/:
8527 In file: default.action <guibutton>[ View ]</guibutton> <guibutton>[ Edit ]</guibutton>
8531 +change-x-forwarded-for{block}
8532 -client-header-filter{hide-tor-exit-notation}
8533 -content-type-overwrite
8534 -crunch-client-header
8535 -crunch-if-none-match
8536 -crunch-incoming-cookies
8537 -crunch-outgoing-cookies
8538 -crunch-server-header
8540 -downgrade-http-version
8541 +fast-redirects {check-decoded-url}
8543 -filter {content-cookies}
8544 -filter {all-popups}
8545 -filter {banners-by-link}
8546 -filter {tiny-textforms}
8547 -filter {frameset-borders}
8548 -filter {demoronizer}
8549 -filter {shockwave-flash}
8550 -filter {quicktime-kioskmode}
8552 -filter {crude-parental}
8553 -filter {site-specifics}
8554 -filter {js-annoyances}
8555 -filter {html-annoyances}
8556 +filter {refresh-tags}
8557 -filter {unsolicited-popups}
8558 +filter {img-reorder}
8559 +filter {banners-by-size}
8561 +filter {jumping-windows}
8562 +filter {ie-exploits}
8569 -handle-as-empty-document
8571 -hide-accept-language
8572 -hide-content-disposition
8573 +hide-from-header{block}
8574 +hide-referer{forge}
8576 -overwrite-last-modified
8577 +prevent-compression
8579 -server-header-filter{xml-to-html}
8580 -server-header-filter{html-to-xml}
8581 +session-cookies-only
8582 +set-image-blocker{blank} }
8585 { +block{Path contains "ads".} +handle-as-image }
8591 Ooops, the <quote>/adsl/</quote> is matching <quote>/ads</quote> in our
8592 configuration! But we did not want this at all! Now we see why we get the
8593 blank page. It is actually triggering two different actions here, and
8594 the effects are aggregated so that the URL is blocked, and &my-app; is told
8595 to treat the block as if it were an image. But this is, of course, all wrong.
8596 We could now add a new action below this (or better in our own
8597 <filename>user.action</filename> file) that explicitly
8598 <emphasis>un</emphasis> blocks (
8599 <link linkend="BLOCK"><quote>{-block}</quote></link>) paths with
8600 <quote>adsl</quote> in them (remember, last match in the configuration
8601 wins). There are various ways to handle such exceptions. Example:
8613 Now the page displays ;-)
8614 Remember to flush your browser's caches when making these kinds of changes to
8615 your configuration to insure that you get a freshly delivered page! Or, try
8616 using <literal>Shift+Reload</literal>.
8620 But now what about a situation where we get no explicit matches like
8627 { +block{Path starts with "ads".} +handle-as-image }
8633 That actually was very helpful and pointed us quickly to where the problem
8634 was. If you don't get this kind of match, then it means one of the default
8635 rules in the first section of <filename>default.action</filename> is causing
8636 the problem. This would require some guesswork, and maybe a little trial and
8637 error to isolate the offending rule. One likely cause would be one of the
8638 <link linkend="FILTER"><quote>+filter</quote></link> actions.
8639 These tend to be harder to troubleshoot.
8640 Try adding the URL for the site to one of aliases that turn off
8641 <link linkend="FILTER"><quote>+filter</quote></link>:
8649 .worldpay.com # for quietpc.com
8657 <quote><literal>{ shop }</literal></quote> is an <quote>alias</quote> that expands to
8658 <quote><literal>{ -filter -session-cookies-only }</literal></quote>.
8659 Or you could do your own exception to negate filtering:
8667 # Disable ALL filter actions for sites in this section
8675 This would turn off all filtering for these sites. This is best
8676 put in <filename>user.action</filename>, for local site
8677 exceptions. Note that when a simple domain pattern is used by itself (without
8678 the subsequent path portion), all sub-pages within that domain are included
8679 automatically in the scope of the action.
8683 Images that are inexplicably being blocked, may well be hitting the
8684 <link linkend="FILTER-BANNERS-BY-SIZE"><quote>+filter{banners-by-size}</quote></link>
8686 that images of certain sizes are ad banners (works well
8687 <emphasis>most of the time</emphasis> since these tend to be standardized).
8691 <quote><literal>{ fragile }</literal></quote> is an alias that disables most
8692 actions that are the most likely to cause trouble. This can be used as a
8693 last resort for problem sites.
8699 # Handle with care: easy to break
8701 mybank.example.com</screen>
8706 <emphasis>Remember to flush caches!</emphasis> Note that the
8707 <literal>mail.google</literal> reference lacks the TLD portion (e.g.
8708 <quote>.com</quote>). This will effectively match any TLD with
8709 <literal>google</literal> in it, such as <literal>mail.google.de.</literal>,
8713 If this still does not work, you will have to go through the remaining
8714 actions one by one to find which one(s) is causing the problem.
8723 This program is free software; you can redistribute it
8724 and/or modify it under the terms of the GNU General
8725 Public License as published by the Free Software
8726 Foundation; either version 2 of the License, or (at
8727 your option) any later version.
8729 This program is distributed in the hope that it will
8730 be useful, but WITHOUT ANY WARRANTY; without even the
8731 implied warranty of MERCHANTABILITY or FITNESS FOR A
8732 PARTICULAR PURPOSE. See the GNU General Public
8733 License for more details.
8735 The GNU General Public License should be included with
8736 this file. If not, you can view it at
8737 http://www.gnu.org/copyleft/gpl.html
8738 or write to the Free Software Foundation, Inc.,
8739 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
projects / privoxy.git / blob