1 <!DOCTYPE article PUBLIC "-//OASIS//DTD DocBook V3.1//EN" [
2 <!entity % dummy "IGNORE">
3 <!entity supported SYSTEM "supported.sgml">
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6 <!entity seealso SYSTEM "seealso.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">
20 <!entity % p-stable "IGNORE">
21 <!entity % p-text "IGNORE"> <!-- define we are not a text only doc -->
22 <!entity % p-doc "INCLUDE"> <!-- and we are a formal doc -->
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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 Copyright (C) 2001-2017 Privoxy Developers https://www.privoxy.org/
42 ========================================================================
43 NOTE: Please read developer-manual/documentation.html before touching
44 anything in this, or other Privoxy documentation.
45 ========================================================================
52 <title>Privoxy &p-version; User Manual</title>
56 <!-- Completely the wrong markup, but very little is allowed -->
57 <!-- in this part of an article. FIXME -->
58 <link linkend="copyright">Copyright</link> &my-copy; 2001-2017 by
59 <ulink url="https://www.privoxy.org/">Privoxy Developers</ulink>
63 <pubdate>$Id: user-manual.sgml,v 2.221 2017/05/20 09:27:54 fabiankeil Exp $</pubdate>
67 Note: the following should generate a separate page, and a live link to it,
68 all nicely done. But it doesn't for some mysterious reason. Please leave
69 commented unless it can be fixed proper. For the time being, the
70 copyright/license declarations will be in their own sgml.
83 This is here to keep vim syntax file from breaking :/
84 If I knew enough to fix it, I would.
85 PLEASE DO NOT REMOVE! HB: hal@foobox.net
91 The <citetitle>Privoxy User Manual</citetitle> gives users information on how to
92 install, configure and use <ulink
93 url="https://www.privoxy.org/">Privoxy</ulink>.
96 <!-- Include privoxy.sgml boilerplate: -->
98 <!-- end privoxy.sgml -->
101 You can find the latest version of the <citetitle>Privoxy User Manual</citetitle> at <ulink
102 url="https://www.privoxy.org/user-manual/">https://www.privoxy.org/user-manual/</ulink>.
103 Please see the <link linkend="contact">Contact section</link> on how to
104 contact the developers.
111 <!-- ~~~~~ New section ~~~~~ -->
112 <sect1 label="1" id="introduction"><title>Introduction</title>
114 This documentation is included with the current &p-status; version of
115 <application>Privoxy</application>, &p-version;<![%p-not-stable;[,
116 and is mostly complete at this point. The most up to date reference for the
117 time being is still the comments in the source files and in the individual
118 configuration files. Development of a new version is currently nearing
119 completion, and includes significant changes and enhancements over
123 <!-- include only in non-stable versions -->
126 Since this is a &p-status; version, not all new features are well tested. This
127 documentation may be slightly out of sync as a result (especially with
128 CVS sources). And there <emphasis>may be</emphasis> bugs, though hopefully
133 <!-- ~~~~~ New section ~~~~~ -->
134 <sect2 id="features"><title>Features</title>
136 In addition to the core
137 features of ad blocking and
138 <ulink url="http://en.wikipedia.org/wiki/Browser_cookie">cookie</ulink> management,
139 <application>Privoxy</application> provides many supplemental
140 features<![%p-not-stable;[, some of them currently under development]]>,
141 that give the end-user more control, more privacy and more freedom:
143 <!-- Include newfeatures.sgml boilerplate here: -->
145 <!-- end boilerplate -->
150 <!-- ~ End section ~ -->
153 <!-- ~~~~~ New section ~~~~~ -->
154 <sect1 id="installation"><title>Installation</title>
157 <application>Privoxy</application> is available both in convenient pre-compiled
158 packages for a wide range of operating systems, and as raw source code.
159 For most users, we recommend using the packages, which can be downloaded from our
160 <ulink url="https://sourceforge.net/projects/ijbswa/">Privoxy Project
166 On some platforms, the installer may remove previously installed versions, if
167 found. (See below for your platform). In any case <emphasis>be sure to backup
168 your old configuration if it is valuable to you.</emphasis> See the <link
169 linkend="upgradersnote">note to upgraders</link> section below.
172 <!-- ~~~~~ New section ~~~~~ -->
173 <sect2 id="installation-packages"><title>Binary Packages</title>
175 How to install the binary packages depends on your operating system:
178 <!-- XXX: The installation sections should be sorted -->
180 <!-- ~~~~~ New section ~~~~~ -->
181 <sect3 id="installation-deb"><title>Debian and Ubuntu</title>
183 DEBs can be installed with <literal>apt-get install privoxy</literal>,
184 and will use <filename>/etc/privoxy</filename> for the location of
189 <!-- ~~~~~ New section ~~~~~ -->
190 <sect3 id="installation-pack-win"><title>Windows</title>
193 Just double-click the installer, which will guide you through
194 the installation process. You will find the configuration files
195 in the same directory as you installed <application>Privoxy</application> in.
198 Version 3.0.5 beta introduced full <application>Windows</application> service
199 functionality. On Windows only, the <application>Privoxy</application>
200 program has two new command line arguments to install and uninstall
201 <application>Privoxy</application> as a <emphasis>service</emphasis>.
205 <term>Arguments:</term>
208 <replaceable class="parameter">--install</replaceable>[:<replaceable class="parameter">service_name</replaceable>]
211 <replaceable class="parameter">--uninstall</replaceable>[:<replaceable class="parameter">service_name</replaceable>]
217 After invoking <application>Privoxy</application> with
218 <command>--install</command>, you will need to bring up the
219 <application>Windows</application> service console to assign the user you
220 want <application>Privoxy</application> to run under, and whether or not you
221 want it to run whenever the system starts. You can start the
222 <application>Windows</application> services console with the following
223 command: <command>services.msc</command>. If you do not take the manual step
224 of modifying <application>Privoxy's</application> service settings, it will
225 not start. Note too that you will need to give Privoxy a user account that
226 actually exists, or it will not be permitted to
227 write to its log and configuration files.
232 <!-- ~~~~~ New section ~~~~~ -->
233 <sect3 id="installation-os2"><title>OS/2</title>
236 First, make sure that no previous installations of
237 <application>Junkbuster</application> and / or
238 <application>Privoxy</application> are left on your
239 system. Check that no <application>Junkbuster</application>
240 or <application>Privoxy</application> objects are in
245 Then, just double-click the WarpIN self-installing archive, which will
246 guide you through the installation process. A shadow of the
247 <application>Privoxy</application> executable will be placed in your
248 startup folder so it will start automatically whenever OS/2 starts.
252 The directory you choose to install <application>Privoxy</application>
253 into will contain all of the configuration files.
257 <!-- ~~~~~ New section ~~~~~ -->
258 <sect3 id="installation-mac"><title>Mac OS X</title>
260 Installation instructions for the OS X platform depend upon whether
261 you downloaded a ready-built installation package (.pkg or .mpkg) or have
262 downloaded the source code.
265 <sect3 renderas="sect4" id="OS-X-install-from-package">
266 <title>Installation from ready-built package</title>
268 The downloaded file will either be a .pkg (for OS X 10.5 upwards) or a bzipped
269 .mpkg file (for OS X 10.4). The former can be double-clicked as is and the
270 installation will start; double-clicking the latter will unzip the .mpkg file
271 which can then be double-clicked to commence the installation.
274 The privoxy service will automatically start after a successful installation
275 (and thereafter every time your computer starts up) however you will need to
276 configure your web browser(s) to use it. To do so, configure them to use a
277 proxy for HTTP and HTTPS at the address 127.0.0.1:8118.
280 To prevent the privoxy service from automatically starting when your computer
281 starts up, remove or rename the file <literal>/Library/LaunchDaemons/org.ijbswa.privoxy.plist</literal>
282 (on OS X 10.5 and higher) or the folder named
283 <literal>/Library/StartupItems/Privoxy</literal> (on OS X 10.4 'Tiger').
286 To manually start or stop the privoxy service, use the scripts startPrivoxy.sh
287 and stopPrivoxy.sh supplied in /Applications/Privoxy. They must be run from an
288 administrator account, using sudo.
291 To uninstall, run /Applications/Privoxy/uninstall.command as sudo from an
292 administrator account.
295 <sect3 renderas="sect4" id="OS-X-install-from-source">
296 <title>Installation from source</title>
298 To build and install the Privoxy source code on OS X you will need to obtain
299 the macsetup module from the Privoxy Sourceforge CVS repository (refer to
300 Sourceforge help for details of how to set up a CVS client to have read-only
301 access to the repository). This module contains scripts that leverage the usual
302 open-source tools (available as part of Apple's free of charge Xcode
303 distribution or via the usual open-source software package managers for OS X
304 (MacPorts, Homebrew, Fink etc.) to build and then install the privoxy binary
305 and associated files. The macsetup module's README file contains complete
306 instructions for its use.
309 The privoxy service will automatically start after a successful installation
310 (and thereafter every time your computer starts up) however you will need to
311 configure your web browser(s) to use it. To do so, configure them to use a
312 proxy for HTTP and HTTPS at the address 127.0.0.1:8118.
315 To prevent the privoxy service from automatically starting when your computer
316 starts up, remove or rename the file <literal>/Library/LaunchDaemons/org.ijbswa.privoxy.plist</literal>
317 (on OS X 10.5 and higher) or the folder named
318 <literal>/Library/StartupItems/Privoxy</literal> (on OS X 10.4 'Tiger').
321 To manually start or stop the privoxy service, use the Privoxy Utility
322 for Mac OS X (also part of the macsetup module). This application can start
323 and stop the privoxy service and display its log and configuration files.
326 To uninstall, run the macsetup module's uninstall.sh as sudo from an
327 administrator account.
331 <!-- ~~~~~ New section ~~~~~ -->
332 <sect3 id="installation-freebsd"><title>FreeBSD</title>
335 Privoxy is part of FreeBSD's Ports Collection, you can build and install
336 it with <literal>cd /usr/ports/www/privoxy; make install clean</literal>.
342 <!-- ~~~~~ New section ~~~~~ -->
343 <sect2 id="installation-source"><title>Building from Source</title>
346 The most convenient way to obtain the <application>Privoxy</application> sources
347 is to download the source tarball from our
348 <ulink url="https://sourceforge.net/projects/ijbswa/files/Sources/">project download
353 If you like to live on the bleeding edge and are not afraid of using
354 possibly unstable development versions, you can check out the up-to-the-minute
355 version directly from <ulink url="https://sourceforge.net/p/ijbswa/code/?source=navbar">the
356 CVS repository</ulink>.
358 deprecated...out of business.
359 or simply download <ulink
360 url="http://cvs.sourceforge.net/cvstarballs/ijbswa-cvsroot.tar.bz2">the nightly CVS
365 <!-- include buildsource.sgml boilerplate: -->
367 <!-- end boilerplate -->
370 <!-- ~~~~~ New section ~~~~~ -->
371 <sect2 id="installation-keepupdated"><title>Keeping your Installation Up-to-Date</title>
374 If you wish to receive an email notification whenever we release updates of
375 <application>Privoxy</application> or the actions file, <ulink
376 url="https://lists.privoxy.org/mailman/listinfo/privoxy-announce">subscribe
377 to our announce mailing list</ulink>, privoxy-announce@lists.privoxy.org.
381 In order not to lose your personal changes and adjustments when updating
382 to the latest <literal>default.action</literal> file we <emphasis>strongly
383 recommend</emphasis> that you use <literal>user.action</literal> and
384 <literal>user.filter</literal> for your local
385 customizations of <application>Privoxy</application>. See the <link
386 linkend="actions-file">Chapter on actions files</link> for details.
394 <!-- ~ End section ~ -->
396 <!-- ~~~~~ New section ~~~~~ -->
397 <sect1 id="whatsnew">
398 <title>What's New in this Release</title>
402 <!-- ~~~~~ New section ~~~~~ -->
404 <sect2 id="upgradersnote">
405 <title>Note to Upgraders</title>
408 A quick list of things to be aware of before upgrading from earlier
409 versions of <application>Privoxy</application>:
417 The recommended way to upgrade &my-app; is to backup your old
418 configuration files, install the new ones, verify that &my-app;
419 is working correctly and finally merge back your changes using
420 <application>diff</application> and maybe <application>patch</application>.
423 There are a number of new features in each &my-app; release and
424 most of them have to be explicitly enabled in the configuration
425 files. Old configuration files obviously don't do that and due
426 to syntax changes using old configuration files with a new
427 &my-app; isn't always possible anyway.
432 Note that some installers remove earlier versions completely,
433 including configuration files, therefore you should really save
434 any important configuration files!
439 On the other hand, other installers don't overwrite existing configuration
440 files, thinking you will want to do that yourself.
445 In the default configuration only fatal errors are logged now.
446 You can change that in the <link linkend="DEBUG">debug section</link>
447 of the configuration file. You may also want to enable more verbose
448 logging until you verified that the new &my-app; version is working
455 Three other config file settings are now off by default:
456 <link linkend="enable-remote-toggle">enable-remote-toggle</link>,
457 <link linkend="enable-remote-http-toggle">enable-remote-http-toggle</link>,
458 and <link linkend="enable-edit-actions">enable-edit-actions</link>.
459 If you use or want these, you will need to explicitly enable them, and
460 be aware of the security issues involved.
467 What constitutes a <quote>default</quote> configuration has changed,
468 and you may want to review which actions are <quote>on</quote> by
469 default. This is primarily a matter of emphasis, but some features
470 you may have been used to, may now be <quote>off</quote> by default.
471 There are also a number of new actions and filters you may want to
472 consider, most of which are not fully incorporated into the default
473 settings as yet (see above).
480 The default actions setting is now <literal>Cautious</literal>. Previous
481 releases had a default setting of <literal>Medium</literal>. Experienced
482 users may want to adjust this, as it is fairly conservative by &my-app;
483 standards and past practices. See <ulink
484 url="http://config.privoxy.org/edit-actions-list?f=default">
485 http://config.privoxy.org/edit-actions-list?f=default</ulink>. New users
486 should try the default settings for a while before turning up the volume.
492 The default setting has filtering turned <emphasis>off</emphasis>, which
493 subsequently means that compression is <emphasis>on</emphasis>. Remember
494 that filtering does not work on compressed pages, so if you use, or want to
495 use, filtering, you will need to force compression off. Example:
499 { +<link linkend="filter">filter</link>{google} +<link linkend="prevent-compression">prevent-compression</link> }
503 Or if you use a number of filters, or filter many sites, you may just want
504 to turn off compression for all sites in
505 <filename>default.action</filename> (or
506 <filename>user.action</filename>).
513 Also, <link linkend="SESSION-COOKIES-ONLY">session-cookies-only</link> is
514 off by default now. If you've liked this feature in the past, you may want
515 to turn it back on in <filename>user.action</filename> now.
522 Some installers may not automatically start
523 <application>Privoxy</application> after installation.
534 <!-- ~~~~~ New section ~~~~~ -->
535 <sect1 id="quickstart"><title>Quickstart to Using Privoxy</title>
541 Install <application>Privoxy</application>. See the <link
542 linkend="installation">Installation Section</link> below for platform specific
549 Advanced users and those who want to offer <application>Privoxy</application>
550 service to more than just their local machine should check the <link
551 linkend="config">main config file</link>, especially the <link
552 linkend="access-control">security-relevant</link> options. These are
559 Start <application>Privoxy</application>, if the installation program has
560 not done this already (may vary according to platform). See the section
561 <link linkend="startup">Starting <application>Privoxy</application></link>.
567 Set your browser to use <application>Privoxy</application> as HTTP and
568 HTTPS (SSL) <ulink url="http://en.wikipedia.org/wiki/Proxy_server">proxy</ulink>
569 by setting the proxy configuration for address of
570 <literal>127.0.0.1</literal> and port <literal>8118</literal>.
571 <emphasis>DO NOT</emphasis> activate proxying for <literal>FTP</literal> or
572 any protocols besides HTTP and HTTPS (SSL) unless you intend to prevent your
573 browser from using these protocols.
579 Flush your browser's disk and memory caches, to remove any cached ad images.
580 If using <application>Privoxy</application> to manage
581 <ulink url="http://en.wikipedia.org/wiki/Browser_cookie">cookies</ulink>,
582 you should remove any currently stored cookies too.
588 A default installation should provide a reasonable starting point for
589 most. There will undoubtedly be occasions where you will want to adjust the
590 configuration, but that can be dealt with as the need arises. Little
591 to no initial configuration is required in most cases, you may want
593 <ulink url="config.html#ENABLE-EDIT-ACTIONS">web-based action editor</ulink> though.
594 Be sure to read the warnings first.
597 See the <link linkend="configuration">Configuration section</link> for more
598 configuration options, and how to customize your installation.
599 You might also want to look at the <link
600 linkend="quickstart-ad-blocking">next section</link> for a quick
601 introduction to how <application>Privoxy</application> blocks ads and
608 If you experience ads that slip through, innocent images that are
609 blocked, or otherwise feel the need to fine-tune
610 <application>Privoxy's</application> behavior, take a look at the <link
611 linkend="actions-file">actions files</link>. As a quick start, you might
612 find the <link linkend="act-examples">richly commented examples</link>
613 helpful. You can also view and edit the actions files through the <ulink
614 url="http://config.privoxy.org">web-based user interface</ulink>. The
615 Appendix <quote><link linkend="actionsanat">Troubleshooting: Anatomy of an
616 Action</link></quote> has hints on how to understand and debug actions that
617 <quote>misbehave</quote>.
623 Please see the section <link linkend="contact">Contacting the
624 Developers</link> on how to report bugs, problems with websites or to get
631 Now enjoy surfing with enhanced control, comfort and privacy!
639 <!-- ~~~~~ New section ~~~~~ -->
641 <sect2 id="quickstart-ad-blocking">
642 <title>Quickstart to Ad Blocking</title>
644 NOTE: This section is deliberately redundant for those that don't
645 want to read the whole thing (which is getting lengthy).
648 Ad blocking is but one of <application>Privoxy's</application>
649 array of features. Many of these features are for the technically minded advanced
650 user. But, ad and banner blocking is surely common ground for everybody.
653 This section will provide a quick summary of ad blocking so
654 you can get up to speed quickly without having to read the more extensive
655 information provided below, though this is highly recommended.
658 First a bit of a warning ... blocking ads is much like blocking SPAM: the
659 more aggressive you are about it, the more likely you are to block
660 things that were not intended. And the more likely that some things
661 may not work as intended. So there is a trade off here. If you want
662 extreme ad free browsing, be prepared to deal with more
663 <quote>problem</quote> sites, and to spend more time adjusting the
664 configuration to solve these unintended consequences. In short, there is
665 not an easy way to eliminate <emphasis>all</emphasis> ads. Either take
666 the easy way and settle for <emphasis>most</emphasis> ads blocked with the
667 default configuration, or jump in and tweak it for your personal surfing
668 habits and preferences.
671 Secondly, a brief explanation of <application>Privoxy's </application>
672 <quote>actions</quote>. <quote>Actions</quote> in this context, are
673 the directives we use to tell <application>Privoxy</application> to perform
674 some task relating to HTTP transactions (i.e. web browsing). We tell
675 <application>Privoxy</application> to take some <quote>action</quote>. Each
676 action has a unique name and function. While there are many potential
677 <application>actions</application> in <application>Privoxy's</application>
678 arsenal, only a few are used for ad blocking. <link
679 linkend="actions">Actions</link>, and <link linkend="actions-file">action
680 configuration files</link>, are explained in depth below.
683 Actions are specified in <application>Privoxy's</application> configuration,
684 followed by one or more URLs to which the action should apply. URLs
685 can actually be URL type <link linkend="af-patterns">patterns</link> that use
686 wildcards so they can apply potentially to a range of similar URLs. The
687 actions, together with the URL patterns are called a section.
690 When you connect to a website, the full URL will either match one or more
691 of the sections as defined in <application>Privoxy's</application> configuration,
692 or not. If so, then <application>Privoxy</application> will perform the
693 respective actions. If not, then nothing special happens. Furthermore, web
694 pages may contain embedded, secondary URLs that your web browser will
695 use to load additional components of the page, as it parses the
696 original page's HTML content. An ad image for instance, is just an URL
697 embedded in the page somewhere. The image itself may be on the same server,
698 or a server somewhere else on the Internet. Complex web pages will have many
699 such embedded URLs. &my-app; can deal with each URL individually, so, for
700 instance, the main page text is not touched, but images from such-and-such
705 The most important actions for basic ad blocking are: <literal><link
706 linkend="block">block</link></literal>, <literal><link
707 linkend="handle-as-image">handle-as-image</link></literal>,
709 linkend="handle-as-empty-document">handle-as-empty-document</link></literal>,and
710 <literal><link linkend="set-image-blocker">set-image-blocker</link></literal>:
718 <literal><link linkend="block">block</link></literal> - this is perhaps
719 the single most used action, and is particularly important for ad blocking.
720 This action stops any contact between your browser and any URL patterns
721 that match this action's configuration. It can be used for blocking ads,
722 but also anything that is determined to be unwanted. By itself, it simply
723 stops any communication with the remote server and sends
724 <application>Privoxy</application>'s own built-in BLOCKED page instead to
725 let you now what has happened (with some exceptions, see below).
731 <literal><link linkend="handle-as-image">handle-as-image</link></literal> -
732 tells <application>Privoxy</application> to treat this URL as an image.
733 <application>Privoxy</application>'s default configuration already does this
734 for all common image types (e.g. GIF), but there are many situations where this
735 is not so easy to determine. So we'll force it in these cases. This is particularly
736 important for ad blocking, since only if we know that it's an image of
737 some kind, can we replace it with an image of our choosing, instead of the
738 <application>Privoxy</application> BLOCKED page (which would only result in
739 a <quote>broken image</quote> icon). There are some limitations to this
740 though. For instance, you can't just brute-force an image substitution for
741 an entire HTML page in most situations.
747 <literal><link linkend="handle-as-empty-document">handle-as-empty-document</link></literal> -
748 sends an empty document instead of <application>Privoxy's</application>
749 normal BLOCKED HTML page. This is useful for file types that are neither
750 HTML nor images, such as blocking JavaScript files.
757 linkend="set-image-blocker">set-image-blocker</link></literal> - tells
758 <application>Privoxy</application> what to display in place of an ad image that
759 has hit a block rule. For this to come into play, the URL must match a
760 <literal><link linkend="block">block</link></literal> action somewhere in the
761 configuration, <emphasis>and</emphasis>, it must also match an
762 <literal><link linkend="handle-as-image">handle-as-image</link></literal> action.
765 The configuration options on what to display instead of the ad are:
769 <emphasis>pattern</emphasis> - a checkerboard pattern, so that an ad
770 replacement is obvious. This is the default.
775 <emphasis>blank</emphasis> - A very small empty GIF image is displayed.
776 This is the so-called <quote>invisible</quote> configuration option.
781 <emphasis>http://<URL></emphasis> - A redirect to any image anywhere
782 of the user's choosing (advanced usage).
791 Advanced users will eventually want to explore &my-app;
792 <literal><link linkend="filter">filters</link></literal> as well. Filters
793 are very different from <literal><link
794 linkend="block">blocks</link></literal>.
795 A <quote>block</quote> blocks a site, page, or unwanted contented. Filters
796 are a way of filtering or modifying what is actually on the page. An example
797 filter usage: a text replacement of <quote>no-no</quote> for
798 <quote>nasty-word</quote>. That is a very simple example. This process can be
799 used for ad blocking, but it is more in the realm of advanced usage and has
800 some pitfalls to be wary off.
804 The quickest way to adjust any of these settings is with your browser through
805 the special <application>Privoxy</application> editor at <ulink
806 url="http://config.privoxy.org/show-status">http://config.privoxy.org/show-status</ulink>
807 (shortcut: <ulink url="http://p.p/">http://p.p/show-status</ulink>). This
808 is an internal page, and does not require Internet access.
812 Note that as of <application>Privoxy</application> 3.0.7 beta the
813 action editor is disabled by default. Check the
814 <ulink url="config.html#ENABLE-EDIT-ACTIONS">enable-edit-actions
815 section in the configuration file</ulink> to learn why and in which
816 cases it's safe to enable again.
820 If you decided to enable the action editor, select the appropriate
821 <quote>actions</quote> file, and click
822 <quote><guibutton>Edit</guibutton></quote>. It is best to put personal or
823 local preferences in <filename>user.action</filename> since this is not
824 meant to be overwritten during upgrades, and will over-ride the settings in
825 other files. Here you can insert new <quote>actions</quote>, and URLs for ad
826 blocking or other purposes, and make other adjustments to the configuration.
827 <application>Privoxy</application> will detect these changes automatically.
831 A quick and simple step by step example:
839 Right click on the ad image to be blocked, then select
840 <quote><guimenuitem>Copy Link Location</guimenuitem></quote> from the
848 url="http://config.privoxy.org/show-status">http://config.privoxy.org/show-status</ulink>
853 Find <filename>user.action</filename> in the top section, and click
854 on <quote><guibutton>Edit</guibutton></quote>:
857 <!-- image of editor and actions files selections -->
859 <figure pgwide="0" float="0"><title>Actions Files in Use</title>
862 <imagedata fileref="files-in-use.jpg" format="jpg">
865 <phrase>[ Screenshot of Actions Files in Use ]</phrase>
874 You should have a section with only
875 <literal><link linkend="block">block</link></literal> listed under
876 <quote>Actions:</quote>.
877 If not, click a <quote><guibutton>Insert new section below</guibutton></quote>
878 button, and in the new section that just appeared, click the
879 <guibutton>Edit</guibutton> button right under the word <quote>Actions:</quote>.
880 This will bring up a list of all actions. Find
881 <literal><link linkend="block">block</link></literal> near the top, and click
882 in the <quote>Enabled</quote> column, then <quote><guibutton>Submit</guibutton></quote>
888 Now, in the <literal><link linkend="block">block</link></literal> actions section,
889 click the <quote><guibutton>Add</guibutton></quote> button, and paste the URL the
890 browser got from <quote><guimenuitem>Copy Link Location</guimenuitem></quote>.
891 Remove the <literal>http://</literal> at the beginning of the URL. Then, click
892 <quote><guibutton>Submit</guibutton></quote> (or
893 <quote><guibutton>OK</guibutton></quote> if in a pop-up window).
898 Now go back to the original page, and press <keycap>SHIFT-Reload</keycap>
899 (or flush all browser caches). The image should be gone now.
907 This is a very crude and simple example. There might be good reasons to use a
908 wildcard pattern match to include potentially similar images from the same
909 site. For a more extensive explanation of <quote>patterns</quote>, and
910 the entire actions concept, see <link linkend="actions-file">the Actions
915 For advanced users who want to hand edit their config files, you might want
916 to now go to the <link linkend="act-examples">Actions Files Tutorial</link>.
917 The ideas explained therein also apply to the web-based editor.
920 There are also various
921 <link linkend="filter">filters</link> that can be used for ad blocking
922 (filters are a special subset of actions). These
923 fall into the <quote>advanced</quote> usage category, and are explained in
924 depth in later sections.
931 <!-- ~ End section ~ -->
934 <!-- ~~~~~ New section ~~~~~ -->
936 <title>Starting Privoxy</title>
938 Before launching <application>Privoxy</application> for the first time, you
939 will want to configure your browser(s) to use
940 <application>Privoxy</application> as a HTTP and HTTPS (SSL)
941 <ulink url="http://en.wikipedia.org/wiki/Proxy_server">proxy</ulink>. The default is
942 127.0.0.1 (or localhost) for the proxy address, and port 8118 (earlier versions
943 used port 8000). This is the one configuration step <emphasis>that must be done
947 Please note that <application>Privoxy</application> can only proxy HTTP and
948 HTTPS traffic. It will not work with FTP or other protocols.
951 <!-- image of Mozilla Proxy configuration -->
953 <figure pgwide="0" float="0"><title>Proxy Configuration Showing
954 Mozilla/Netscape HTTP and HTTPS (SSL) Settings</title>
957 <imagedata fileref="proxy_setup.jpg" format="jpg">
960 <phrase>[ Screenshot of Mozilla Proxy Configuration ]</phrase>
968 With <application>Firefox</application>, this is typically set under:
972 <guibutton>Tools</guibutton> -> <guibutton>Options</guibutton> -> <guibutton>Advanced</guibutton> -> <guibutton>Network</guibutton> -><guibutton>Connection</guibutton> -> <guibutton>Settings</guibutton>
976 Or optionally on some platforms:
980 <guibutton>Edit</guibutton> -> <guibutton>Preferences</guibutton> -> <guibutton>General</guibutton> -> <guibutton>Connection Settings</guibutton> -> <guibutton>Manual Proxy Configuration</guibutton>
985 With <application>Netscape</application> (and
986 <application>Mozilla</application>), this can be set under:
991 <!-- Mix ascii and gui art, something for everybody -->
992 <!-- spacing on this is tricky -->
993 <guibutton>Edit</guibutton> -> <guibutton>Preferences</guibutton> -> <guibutton>Advanced</guibutton> -> <guibutton>Proxies</guibutton> -> <guibutton>HTTP Proxy</guibutton>
997 For <application>Internet Explorer v.5-7</application>:
1001 <guibutton>Tools</guibutton> -> <guibutton>Internet Options</guibutton> -> <guibutton>Connections</guibutton> -> <guibutton>LAN Settings</guibutton>
1005 Then, check <quote>Use Proxy</quote> and fill in the appropriate info
1006 (Address: 127.0.0.1, Port: 8118). Include HTTPS (SSL), if you want HTTPS
1007 proxy support too (sometimes labeled <quote>Secure</quote>). Make sure any
1008 checkboxes like <quote>Use the same proxy server for all protocols</quote> is
1009 <emphasis>UNCHECKED</emphasis>. You want only HTTP and HTTPS (SSL)!
1012 <!-- image of IE Proxy configuration -->
1014 <figure pgwide="0" float="0"><title>Proxy Configuration Showing
1015 Internet Explorer HTTP and HTTPS (Secure) Settings</title>
1018 <imagedata fileref="proxy2.jpg" format="jpg">
1021 <phrase>[ Screenshot of IE Proxy Configuration ]</phrase>
1029 After doing this, flush your browser's disk and memory caches to force a
1030 re-reading of all pages and to get rid of any ads that may be cached. Remove
1031 any <ulink url="http://en.wikipedia.org/wiki/Browser_cookie">cookies</ulink>,
1032 if you want <application>Privoxy</application> to manage that. You are now
1033 ready to start enjoying the benefits of using
1034 <application>Privoxy</application>!
1038 <application>Privoxy</application> itself is typically started by specifying the
1039 main configuration file to be used on the command line. If no configuration
1040 file is specified on the command line, <application>Privoxy</application>
1041 will look for a file named <filename>config</filename> in the current
1042 directory. Except on Win32 where it will try <filename>config.txt</filename>.
1045 <sect2 id="start-debian">
1046 <title>Debian</title>
1048 We use a script. Note that Debian typically starts &my-app; upon booting per
1049 default. It will use the file
1050 <filename>/etc/privoxy/config</filename> as its main configuration
1055 # /etc/init.d/privoxy start
1060 <sect2 id="start-freebsd">
1061 <title>FreeBSD and ElectroBSD</title>
1063 To start <application>Privoxy</application> upon booting, add
1064 "privoxy_enable='YES'" to <filename>/etc/rc.conf</filename>.
1065 <application>Privoxy</application> will use
1066 <filename>/usr/local/etc/privoxy/config</filename> as its main
1070 If you installed <application>Privoxy</application> into a jail, the
1071 paths above are relative to the jail root.
1074 To start <application>Privoxy</application> manually, run:
1078 # service privoxy onestart
1083 <sect2 id="start-windows">
1084 <title>Windows</title>
1086 Click on the &my-app; Icon to start <application>Privoxy</application>. If no configuration file is
1087 specified on the command line, <application>Privoxy</application> will look
1088 for a file named <filename>config.txt</filename>. Note that Windows will
1089 automatically start &my-app; when the system starts if you chose that option
1093 <application>Privoxy</application> can run with full Windows service functionality.
1094 On Windows only, the &my-app; program has two new command line arguments
1095 to install and uninstall &my-app; as a service. See the
1096 <link linkend="installation-pack-win">Windows Installation
1097 instructions</link> for details.
1101 <sect2 id="start-unices">
1102 <title>Generic instructions for Unix derivates (Solaris, NetBSD, HP-UX etc.)</title>
1104 Example Unix startup command:
1108 # /usr/sbin/privoxy --user privoxy /etc/privoxy/config
1112 Note that if you installed <application>Privoxy</application> through
1113 a package manager, the package will probably contain a platform-specific
1114 script or configuration file to start <application>Privoxy</application>
1119 <sect2 id="start-os2">
1122 During installation, <application>Privoxy</application> is configured to
1123 start automatically when the system restarts. You can start it manually by
1124 double-clicking on the <application>Privoxy</application> icon in the
1125 <application>Privoxy</application> folder.
1129 <sect2 id="start-macosx">
1130 <title>Mac OS X</title>
1132 The privoxy service will automatically start after a successful installation
1133 (and thereafter every time your computer starts up) however you will need to
1134 configure your web browser(s) to use it. To do so, configure them to use a
1135 proxy for HTTP and HTTPS at the address 127.0.0.1:8118.
1138 To prevent the privoxy service from automatically starting when your computer
1139 starts up, remove or rename the file <literal>/Library/LaunchDaemons/org.ijbswa.privoxy.plist</literal>
1140 (on OS X 10.5 and higher) or the folder named
1141 <literal>/Library/StartupItems/Privoxy</literal> (on OS X 10.4 'Tiger').
1144 To manually start or stop the privoxy service, use the scripts startPrivoxy.sh
1145 and stopPrivoxy.sh supplied in /Applications/Privoxy. They must be run from an
1146 administrator account, using sudo.
1154 See the section <link linkend="cmdoptions">Command line options</link> for
1158 must find a better place for this paragraph
1161 The included default configuration files should give a reasonable starting
1162 point. Most of the per site configuration is done in the
1163 <ulink url="actions-file.html"><quote>actions</quote></ulink> files. These are
1164 where various cookie actions are defined, ad and banner blocking, and other
1165 aspects of <application>Privoxy</application> configuration. There are several
1166 such files included, with varying levels of aggressiveness.
1170 You will probably want to keep an eye out for sites for which you may prefer
1171 persistent cookies, and add these to your actions configuration as needed. By
1172 default, most of these will be accepted only during the current browser
1173 session (aka <quote>session cookies</quote>), unless you add them to the
1174 configuration. If you want the browser to handle this instead, you will need
1175 to edit <filename>user.action</filename> (or through the web based interface)
1176 and disable this feature. If you use more than one browser, it would make
1177 more sense to let <application>Privoxy</application> handle this. In which
1178 case, the browser(s) should be set to accept all cookies.
1182 Another feature where you will probably want to define exceptions for trusted
1183 sites is the popup-killing (through <ulink
1184 url="actions-file.html#FILTER-POPUPS"><quote>+filter{popups}</quote></ulink>),
1185 because your favorite shopping, banking, or leisure site may need
1186 popups (explained below).
1190 <application>Privoxy</application> does not support all of the optional HTTP/1.1
1191 features yet. In the unlikely event that you experience inexplicable problems
1192 with browsers that use HTTP/1.1 per default
1193 (like <application>Mozilla</application> or recent versions of I.E.), you might
1194 try to force HTTP/1.0 compatibility. For Mozilla, look under <literal>Edit ->
1195 Preferences -> Debug -> Networking</literal>.
1196 Alternatively, set the <quote>+downgrade-http-version</quote> config option in
1197 <filename>default.action</filename> which will downgrade your browser's HTTP
1198 requests from HTTP/1.1 to HTTP/1.0 before processing them.
1202 After running <application>Privoxy</application> for a while, you can
1203 start to fine tune the configuration to suit your personal, or site,
1204 preferences and requirements. There are many, many aspects that can
1205 be customized. <quote>Actions</quote>
1206 can be adjusted by pointing your browser to
1207 <ulink url="http://config.privoxy.org/">http://config.privoxy.org/</ulink>
1208 (shortcut: <ulink url="http://p.p/">http://p.p/</ulink>),
1209 and then follow the link to <quote>View & Change the Current Configuration</quote>.
1210 (This is an internal page and does not require Internet access.)
1214 In fact, various aspects of <application>Privoxy</application>
1215 configuration can be viewed from this page, including
1216 current configuration parameters, source code version numbers,
1217 the browser's request headers, and <quote>actions</quote> that apply
1218 to a given URL. In addition to the actions file
1219 editor mentioned above, <application>Privoxy</application> can also
1220 be turned <quote>on</quote> and <quote>off</quote> (toggled) from this page.
1224 If you encounter problems, try loading the page without
1225 <application>Privoxy</application>. If that helps, enter the URL where
1226 you have the problems into <ulink url="http://p.p/show-url-info">the browser
1227 based rule tracing utility</ulink>. See which rules apply and why, and
1228 then try turning them off for that site one after the other, until the problem
1229 is gone. When you have found the culprit, you might want to turn the rest on
1234 If the above paragraph sounds gibberish to you, you might want to <link
1235 linkend="actions-file">read more about the actions concept</link>
1236 or even dive deep into the <link linkend="actionsanat">Appendix
1241 If you can't get rid of the problem at all, think you've found a bug in
1242 Privoxy, want to propose a new feature or smarter rules, please see the
1243 section <link linkend="contact"><quote>Contacting the
1244 Developers</quote></link> below.
1249 <!-- ~~~~~ New section ~~~~~ -->
1250 <sect2 id="cmdoptions">
1251 <title>Command Line Options</title>
1253 <application>Privoxy</application> may be invoked with the following
1254 command-line options:
1262 <emphasis>--config-test</emphasis>
1265 Exit after loading the configuration files before binding to
1266 the listen address. The exit code signals whether or not the
1267 configuration files have been successfully loaded.
1270 If the exit code is 1, at least one of the configuration files
1271 is invalid, if it is 0, all the configuration files have been
1272 successfully loaded (but may still contain errors that can
1273 currently only be detected at run time).
1276 This option doesn't affect the log setting, combination with
1277 <emphasis>--no-daemon</emphasis> is recommended if a configured
1278 log file shouldn't be used.
1283 <emphasis>--version</emphasis>
1286 Print version info and exit. Unix only.
1291 <emphasis>--help</emphasis>
1294 Print short usage info and exit. Unix only.
1299 <emphasis>--no-daemon</emphasis>
1302 Don't become a daemon, i.e. don't fork and become process group
1303 leader, and don't detach from controlling tty. Unix only.
1308 <emphasis>--pidfile FILE</emphasis>
1311 On startup, write the process ID to <emphasis>FILE</emphasis>. Delete the
1312 <emphasis>FILE</emphasis> on exit. Failure to create or delete the
1313 <emphasis>FILE</emphasis> is non-fatal. If no <emphasis>FILE</emphasis>
1314 option is given, no PID file will be used. Unix only.
1319 <emphasis>--user USER[.GROUP]</emphasis>
1322 After (optionally) writing the PID file, assume the user ID of
1323 <emphasis>USER</emphasis>, and if included the GID of GROUP. Exit if the
1324 privileges are not sufficient to do so. Unix only.
1329 <emphasis>--chroot</emphasis>
1332 Before changing to the user ID given in the <emphasis>--user</emphasis> option,
1333 chroot to that user's home directory, i.e. make the kernel pretend to the &my-app;
1334 process that the directory tree starts there. If set up carefully, this can limit
1335 the impact of possible vulnerabilities in &my-app; to the files contained in that hierarchy.
1341 <emphasis>--pre-chroot-nslookup hostname</emphasis>
1344 Specifies a hostname (for example www.privoxy.org) to look up before doing a chroot.
1345 On some systems, initializing the resolver library involves reading config files from
1346 /etc and/or loading additional shared libraries from /lib.
1347 On these systems, doing a hostname lookup before the chroot reduces
1348 the number of files that must be copied into the chroot tree.
1351 For fastest startup speed, a good value is a hostname that is not in /etc/hosts but that
1352 your local name server (listed in /etc/resolv.conf) can resolve without recursion
1353 (that is, without having to ask any other name servers). The hostname need not exist,
1354 but if it doesn't, an error message (which can be ignored) will be output.
1360 <emphasis>configfile</emphasis>
1363 If no <emphasis>configfile</emphasis> is included on the command line,
1364 <application>Privoxy</application> will look for a file named
1365 <quote>config</quote> in the current directory (except on Win32
1366 where it will look for <quote>config.txt</quote> instead). Specify
1367 full path to avoid confusion. If no config file is found,
1368 <application>Privoxy</application> will fail to start.
1376 On <application>MS Windows</application> only there are two additional
1377 command-line options to allow <application>Privoxy</application> to install and
1378 run as a <emphasis>service</emphasis>. See the
1379 <link linkend="installation-pack-win">Window Installation section</link>
1387 <!-- ~ End section ~ -->
1390 <!-- ~~~~~ New section ~~~~~ -->
1391 <sect1 id="configuration"><title>Privoxy Configuration</title>
1393 All <application>Privoxy</application> configuration is stored
1394 in text files. These files can be edited with a text editor.
1395 Many important aspects of <application>Privoxy</application> can
1396 also be controlled easily with a web browser.
1400 <!-- ~~~~~ New section ~~~~~ -->
1402 <sect2 id="control-with-webbrowser">
1403 <title>Controlling Privoxy with Your Web Browser</title>
1405 <application>Privoxy</application>'s user interface can be reached through the special
1406 URL <ulink url="http://config.privoxy.org/">http://config.privoxy.org/</ulink>
1407 (shortcut: <ulink url="http://p.p/">http://p.p/</ulink>),
1408 which is a built-in page and works without Internet access.
1409 You will see the following section:
1412 <!-- Needs to be put in a table and colorized -->
1415 <bridgehead renderas="sect2"> Privoxy Menu</bridgehead>
1419 ▪ <ulink url="http://config.privoxy.org/show-status">View & change the current configuration</ulink>
1422 ▪ <ulink url="http://config.privoxy.org/show-version">View the source code version numbers</ulink>
1425 ▪ <ulink url="http://config.privoxy.org/show-request">View the request headers.</ulink>
1428 ▪ <ulink url="http://config.privoxy.org/show-url-info">Look up which actions apply to a URL and why</ulink>
1431 ▪ <ulink url="http://config.privoxy.org/toggle">Toggle Privoxy on or off</ulink>
1434 ▪ <ulink
1435 url="https://www.privoxy.org/&p-version;/user-manual/">Documentation</ulink>
1443 This should be self-explanatory. Note the first item leads to an editor for the
1444 <link linkend="actions-file">actions files</link>, which is where the ad, banner,
1445 cookie, and URL blocking magic is configured as well as other advanced features of
1446 <application>Privoxy</application>. This is an easy way to adjust various
1447 aspects of <application>Privoxy</application> configuration. The actions
1448 file, and other configuration files, are explained in detail below.
1452 <quote>Toggle Privoxy On or Off</quote> is handy for sites that might
1453 have problems with your current actions and filters. You can in fact use
1454 it as a test to see whether it is <application>Privoxy</application>
1455 causing the problem or not. <application>Privoxy</application> continues
1456 to run as a proxy in this case, but all manipulation is disabled, i.e.
1457 <application>Privoxy</application> acts like a normal forwarding proxy.
1461 Note that several of the features described above are disabled by default
1462 in <application>Privoxy</application> 3.0.7 beta and later.
1464 <ulink url="config.html">configuration file</ulink> to learn why
1465 and in which cases it's safe to enable them again.
1470 <!-- ~ End section ~ -->
1475 <!-- ~~~~~ New section ~~~~~ -->
1477 <sect2 id="confoverview">
1478 <title>Configuration Files Overview</title>
1480 For Unix, *BSD and Linux, all configuration files are located in
1481 <filename>/etc/privoxy/</filename> by default. For MS Windows, OS/2, and
1482 AmigaOS these are all in the same directory as the
1483 <application>Privoxy</application> executable. <![%p-not-stable;[ The name
1484 and number of configuration files has changed from previous versions, and is
1485 subject to change as development progresses.]]>
1489 The installed defaults provide a reasonable starting point, though
1490 some settings may be aggressive by some standards. For the time being, the
1491 principle configuration files are:
1499 The <link linkend="config">main configuration file</link> is named <filename>config</filename>
1500 on Linux, Unix, BSD, OS/2, and AmigaOS and <filename>config.txt</filename>
1501 on Windows. This is a required file.
1507 <filename>match-all.action</filename> is used to define which <quote>actions</quote>
1508 relating to banner-blocking, images, pop-ups, content modification, cookie handling
1509 etc should be applied by default. It should be the first actions file loaded.
1512 <filename>default.action</filename> defines many exceptions (both positive and negative)
1513 from the default set of actions that's configured in <filename>match-all.action</filename>.
1514 It should be the second actions file loaded and shouldn't be edited by the user.
1517 Multiple actions files may be defined in <filename>config</filename>. These
1518 are processed in the order they are defined. Local customizations and locally
1519 preferred exceptions to the default policies as defined in
1520 <filename>match-all.action</filename> (which you will most probably want
1521 to define sooner or later) are best applied in <filename>user.action</filename>,
1522 where you can preserve them across upgrades. The file isn't installed by all
1523 installers, but you can easily create it yourself with a text editor.
1526 There is also a web based editor that can be accessed from
1528 url="http://config.privoxy.org/show-status">http://config.privoxy.org/show-status</ulink>
1530 url="http://p.p/show-status">http://p.p/show-status</ulink>) for the
1531 various actions files.
1537 <quote>Filter files</quote> (the <link linkend="filter-file">filter
1538 file</link>) can be used to re-write the raw page content, including
1539 viewable text as well as embedded HTML and JavaScript, and whatever else
1540 lurks on any given web page. The filtering jobs are only pre-defined here;
1541 whether to apply them or not is up to the actions files.
1542 <filename>default.filter</filename> includes various filters made
1543 available for use by the developers. Some are much more intrusive than
1544 others, and all should be used with caution. You may define additional
1545 filter files in <filename>config</filename> as you can with
1546 actions files. We suggest <filename>user.filter</filename> for any
1547 locally defined filters or customizations.
1555 The syntax of the configuration and filter files may change between different
1556 Privoxy versions, unfortunately some enhancements cost backwards compatibility.
1557 <!-- Add link to documentation-->
1561 All files use the <quote><literal>#</literal></quote> character to denote a
1562 comment (the rest of the line will be ignored) and understand line continuation
1563 through placing a backslash ("<literal>\</literal>") as the very last character
1564 in a line. If the <literal>#</literal> is preceded by a backslash, it looses
1565 its special function. Placing a <literal>#</literal> in front of an otherwise
1566 valid configuration line to prevent it from being interpreted is called "commenting
1567 out" that line. Blank lines are ignored.
1571 The actions files and filter files
1572 can use Perl style <link linkend="regex">regular expressions</link> for
1573 maximum flexibility.
1577 After making any changes, there is no need to restart
1578 <application>Privoxy</application> in order for the changes to take
1579 effect. <application>Privoxy</application> detects such changes
1580 automatically. Note, however, that it may take one or two additional
1581 requests for the change to take effect. When changing the listening address
1582 of <application>Privoxy</application>, these <quote>wake up</quote> requests
1583 must obviously be sent to the <emphasis>old</emphasis> listening address.
1588 While under development, the configuration content is subject to change.
1589 The below documentation may not be accurate by the time you read this.
1590 Also, what constitutes a <quote>default</quote> setting, may change, so
1591 please check all your configuration files on important issues.
1597 <!-- ~ End section ~ -->
1600 <!-- ~~~~~~~~ New section Header ~~~~~~~~~ -->
1602 <!-- **************************************************** -->
1603 <!-- Include config.sgml here -->
1604 <!-- This is where the entire config file is detailed. -->
1606 <!-- end include -->
1609 <!-- ~ End section ~ -->
1613 <!-- ~~~~~~~~ New section Header ~~~~~~~~~ -->
1615 <sect1 id="actions-file"><title>Actions Files</title>
1619 XXX: similar descriptions are in the Configuration Files sections.
1620 We should only describe them at one place.
1623 The actions files are used to define what <emphasis>actions</emphasis>
1624 <application>Privoxy</application> takes for which URLs, and thus determines
1625 how ad images, cookies and various other aspects of HTTP content and
1626 transactions are handled, and on which sites (or even parts thereof).
1627 There are a number of such actions, with a wide range of functionality.
1628 Each action does something a little different.
1629 These actions give us a veritable arsenal of tools with which to exert
1630 our control, preferences and independence. Actions can be combined so that
1631 their effects are aggregated when applied against a given set of URLs.
1635 are three action files included with <application>Privoxy</application> with
1642 <filename>match-all.action</filename> - is used to define which
1643 <quote>actions</quote> relating to banner-blocking, images, pop-ups,
1644 content modification, cookie handling etc should be applied by default.
1645 It should be the first actions file loaded
1650 <filename>default.action</filename> - defines many exceptions (both
1651 positive and negative) from the default set of actions that's configured
1652 in <filename>match-all.action</filename>. It is a set of rules that should
1653 work reasonably well as-is for most users. This file is only supposed to
1654 be edited by the developers. It should be the second actions file loaded.
1659 <filename>user.action</filename> - is intended to be for local site
1660 preferences and exceptions. As an example, if your ISP or your bank
1661 has specific requirements, and need special handling, this kind of
1662 thing should go here. This file will not be upgraded.
1667 <guibutton>Edit</guibutton> <guibutton>Set to Cautious</guibutton> <guibutton>Set to Medium</guibutton> <guibutton>Set to Advanced</guibutton>
1670 These have increasing levels of aggressiveness <emphasis>and have no
1671 influence on your browsing unless you select them explicitly in the
1672 editor</emphasis>. A default installation should be pre-set to
1673 <literal>Cautious</literal>. New users should try this for a while before
1674 adjusting the settings to more aggressive levels. The more aggressive
1675 the settings, then the more likelihood there is of problems such as sites
1676 not working as they should.
1679 The <guibutton>Edit</guibutton> button allows you to turn each
1680 action on/off individually for fine-tuning. The <guibutton>Cautious</guibutton>
1681 button changes the actions list to low/safe settings which will activate
1682 ad blocking and a minimal set of &my-app;'s features, and subsequently
1683 there will be less of a chance for accidental problems. The
1684 <guibutton>Medium</guibutton> button sets the list to a medium level of
1685 other features and a low level set of privacy features. The
1686 <guibutton>Advanced</guibutton> button sets the list to a high level of
1687 ad blocking and medium level of privacy. See the chart below. The latter
1688 three buttons over-ride any changes via with the
1689 <guibutton>Edit</guibutton> button. More fine-tuning can be done in the
1690 lower sections of this internal page.
1693 While the actions file editor allows to enable these settings in all
1694 actions files, they are only supposed to be enabled in the first one
1695 to make sure you don't unintentionally overrule earlier rules.
1698 The default profiles, and their associated actions, as pre-defined in
1699 <filename>default.action</filename> are:
1702 <table frame=all><title>Default Configurations</title>
1703 <tgroup cols=4 align=left colsep=1 rowsep=1>
1704 <colspec colname=c1>
1705 <colspec colname=c2>
1706 <colspec colname=c3>
1707 <colspec colname=c4>
1710 <entry>Feature</entry>
1711 <entry>Cautious</entry>
1712 <entry>Medium</entry>
1713 <entry>Advanced</entry>
1718 <!-- <entry>f1</entry> -->
1719 <!-- <entry>f2</entry> -->
1720 <!-- <entry>f3</entry> -->
1721 <!-- <entry>f4</entry> -->
1727 <entry>Ad-blocking Aggressiveness</entry>
1728 <entry>medium</entry>
1734 <entry>Ad-filtering by size</entry>
1741 <entry>Ad-filtering by link</entry>
1747 <entry>Pop-up killing</entry>
1748 <entry>blocks only</entry>
1749 <entry>blocks only</entry>
1750 <entry>blocks only</entry>
1754 <entry>Privacy Features</entry>
1756 <entry>medium</entry>
1757 <entry>medium/high</entry>
1761 <entry>Cookie handling</entry>
1763 <entry>session-only</entry>
1768 <entry>Referer forging</entry>
1775 <entry>GIF de-animation</entry>
1782 <entry>Fast redirects</entry>
1789 <entry>HTML taming</entry>
1796 <entry>JavaScript taming</entry>
1803 <entry>Web-bug killing</entry>
1810 <entry>Image tag reordering</entry>
1826 The list of actions files to be used are defined in the main configuration
1827 file, and are processed in the order they are defined (e.g.
1828 <filename>default.action</filename> is typically processed before
1829 <filename>user.action</filename>). The content of these can all be viewed and
1831 url="http://config.privoxy.org/show-status">http://config.privoxy.org/show-status</ulink>.
1832 The over-riding principle when applying actions, is that the last action that
1833 matches a given URL wins. The broadest, most general rules go first
1834 (defined in <filename>default.action</filename>),
1835 followed by any exceptions (typically also in
1836 <filename>default.action</filename>), which are then followed lastly by any
1837 local preferences (typically in <emphasis>user</emphasis><filename>.action</filename>).
1838 Generally, <filename>user.action</filename> has the last word.
1842 An actions file typically has multiple sections. If you want to use
1843 <quote>aliases</quote> in an actions file, you have to place the (optional)
1844 <link linkend="aliases">alias section</link> at the top of that file.
1845 Then comes the default set of rules which will apply universally to all
1846 sites and pages (be <emphasis>very careful</emphasis> with using such a
1847 universal set in <filename>user.action</filename> or any other actions file after
1848 <filename>default.action</filename>, because it will override the result
1849 from consulting any previous file). And then below that,
1850 exceptions to the defined universal policies. You can regard
1851 <filename>user.action</filename> as an appendix to <filename>default.action</filename>,
1852 with the advantage that it is a separate file, which makes preserving your
1853 personal settings across <application>Privoxy</application> upgrades easier.
1857 Actions can be used to block anything you want, including ads, banners, or
1858 just some obnoxious URL whose content you would rather not see. Cookies can be accepted
1859 or rejected, or accepted only during the current browser session (i.e. not
1860 written to disk), content can be modified, some JavaScripts tamed, user-tracking
1861 fooled, and much more. See below for a <link linkend="actions">complete list
1865 <!-- ~~~~~ New section ~~~~~ -->
1866 <sect2 id="right-mix">
1867 <title>Finding the Right Mix</title>
1869 Note that some <link linkend="actions">actions</link>, like cookie suppression
1870 or script disabling, may render some sites unusable that rely on these
1871 techniques to work properly. Finding the right mix of actions is not always easy and
1872 certainly a matter of personal taste. And, things can always change, requiring
1873 refinements in the configuration. In general, it can be said that the more
1874 <quote>aggressive</quote> your default settings (in the top section of the
1875 actions file) are, the more exceptions for <quote>trusted</quote> sites you
1876 will have to make later. If, for example, you want to crunch all cookies per
1877 default, you'll have to make exceptions from that rule for sites that you
1878 regularly use and that require cookies for actually useful purposes, like maybe
1879 your bank, favorite shop, or newspaper.
1883 We have tried to provide you with reasonable rules to start from in the
1884 distribution actions files. But there is no general rule of thumb on these
1885 things. There just are too many variables, and sites are constantly changing.
1886 Sooner or later you will want to change the rules (and read this chapter again :).
1890 <!-- ~~~~~ New section ~~~~~ -->
1891 <sect2 id="how-to-edit">
1892 <title>How to Edit</title>
1894 The easiest way to edit the actions files is with a browser by
1895 using our browser-based editor, which can be reached from <ulink
1896 url="http://config.privoxy.org/show-status">http://config.privoxy.org/show-status</ulink>.
1897 Note: the config file option <link
1898 linkend="enable-edit-actions">enable-edit-actions</link> must be enabled for
1899 this to work. The editor allows both fine-grained control over every single
1900 feature on a per-URL basis, and easy choosing from wholesale sets of defaults
1901 like <quote>Cautious</quote>, <quote>Medium</quote> or
1902 <quote>Advanced</quote>. Warning: the <quote>Advanced</quote> setting is more
1903 aggressive, and will be more likely to cause problems for some sites.
1904 Experienced users only!
1908 If you prefer plain text editing to GUIs, you can of course also directly edit the
1909 the actions files with your favorite text editor. Look at
1910 <filename>default.action</filename> which is richly commented with many
1916 <sect2 id="actions-apply">
1917 <title>How Actions are Applied to Requests</title>
1919 Actions files are divided into sections. There are special sections,
1920 like the <quote><link linkend="aliases">alias</link></quote> sections which will
1921 be discussed later. For now let's concentrate on regular sections: They have a
1922 heading line (often split up to multiple lines for readability) which consist
1923 of a list of actions, separated by whitespace and enclosed in curly braces.
1924 Below that, there is a list of URL and tag patterns, each on a separate line.
1928 To determine which actions apply to a request, the URL of the request is
1929 compared to all URL patterns in each <quote>action file</quote>.
1930 Every time it matches, the list of applicable actions for the request is
1931 incrementally updated, using the heading of the section in which the
1932 pattern is located. The same is done again for tags and tag patterns later on.
1936 If multiple applying sections set the same action differently,
1937 the last match wins. If not, the effects are aggregated.
1938 E.g. a URL might match a regular section with a heading line of <literal>{
1939 +<link linkend="handle-as-image">handle-as-image</link> }</literal>,
1940 then later another one with just <literal>{
1941 +<link linkend="block">block</link> }</literal>, resulting
1942 in <emphasis>both</emphasis> actions to apply. And there may well be
1943 cases where you will want to combine actions together. Such a section then
1949 { +<literal>handle-as-image</literal> +<literal>block{Banner ads.}</literal> }
1950 # Block these as if they were images. Send no block page.
1952 media.example.com/.*banners
1953 .example.com/images/ads/</screen>
1957 You can trace this process for URL patterns and any given URL by visiting <ulink
1958 url="http://config.privoxy.org/show-url-info">http://config.privoxy.org/show-url-info</ulink>.
1962 Examples and more detail on this is provided in the Appendix, <link linkend="ACTIONSANAT">
1963 Troubleshooting: Anatomy of an Action</link> section.
1967 <!-- ~~~~~ New section ~~~~~ -->
1968 <sect2 id="af-patterns">
1969 <title>Patterns</title>
1971 As mentioned, <application>Privoxy</application> uses <quote>patterns</quote>
1972 to determine what <emphasis>actions</emphasis> might apply to which sites and
1973 pages your browser attempts to access. These <quote>patterns</quote> use wild
1974 card type <emphasis>pattern</emphasis> matching to achieve a high degree of
1975 flexibility. This allows one expression to be expanded and potentially match
1976 against many similar patterns.
1980 Generally, an URL pattern has the form
1981 <literal><host><port>/<path></literal>, where the
1982 <literal><host></literal>, the <literal><port></literal>
1983 and the <literal><path></literal> are optional. (This is why the special
1984 <literal>/</literal> pattern matches all URLs). Note that the protocol
1985 portion of the URL pattern (e.g. <literal>http://</literal>) should
1986 <emphasis>not</emphasis> be included in the pattern. This is assumed already!
1989 The pattern matching syntax is different for the host and path parts of
1990 the URL. The host part uses a simple globbing type matching technique,
1991 while the path part uses more flexible
1992 <ulink url="http://en.wikipedia.org/wiki/Regular_expressions"><quote>Regular
1993 Expressions</quote></ulink> (POSIX 1003.2).
1996 The port part of a pattern is a decimal port number preceded by a colon
1997 (<literal>:</literal>). If the host part contains a numerical IPv6 address,
1998 it has to be put into angle brackets
1999 (<literal><</literal>, <literal>></literal>).
2004 <term><literal>www.example.com/</literal></term>
2007 is a host-only pattern and will match any request to <literal>www.example.com</literal>,
2008 regardless of which document on that server is requested. So ALL pages in
2009 this domain would be covered by the scope of this action. Note that a
2010 simple <literal>example.com</literal> is different and would NOT match.
2015 <term><literal>www.example.com</literal></term>
2018 means exactly the same. For host-only patterns, the trailing <literal>/</literal> may
2024 <term><literal>www.example.com/index.html</literal></term>
2027 matches all the documents on <literal>www.example.com</literal>
2028 whose name starts with <literal>/index.html</literal>.
2033 <term><literal>www.example.com/index.html$</literal></term>
2036 matches only the single document <literal>/index.html</literal>
2037 on <literal>www.example.com</literal>.
2042 <term><literal>/index.html$</literal></term>
2045 matches the document <literal>/index.html</literal>, regardless of the domain,
2046 i.e. on <emphasis>any</emphasis> web server anywhere.
2051 <term><literal>/</literal></term>
2054 Matches any URL because there's no requirement for either the
2055 domain or the path to match anything.
2060 <term><literal>:8000/</literal></term>
2063 Matches any URL pointing to TCP port 8000.
2068 <term><literal>10.0.0.1/</literal></term>
2071 Matches any URL with the host address <literal>10.0.0.1</literal>.
2072 (Note that the real URL uses plain brackets, not angle brackets.)
2077 <term><literal><2001:db8::1>/</literal></term>
2080 Matches any URL with the host address <literal>2001:db8::1</literal>.
2081 (Note that the real URL uses plain brackets, not angle brackets.)
2086 <term><literal>index.html</literal></term>
2089 matches nothing, since it would be interpreted as a domain name and
2090 there is no top-level domain called <literal>.html</literal>. So its
2098 <!-- ~~~~~ New section ~~~~~ -->
2099 <sect3 id="host-pattern"><title>The Host Pattern</title>
2102 The matching of the host part offers some flexible options: if the
2103 host pattern starts or ends with a dot, it becomes unanchored at that end.
2104 The host pattern is often referred to as domain pattern as it is usually
2105 used to match domain names and not IP addresses.
2111 <term><literal>.example.com</literal></term>
2114 matches any domain with first-level domain <literal>com</literal>
2115 and second-level domain <literal>example</literal>.
2116 For example <literal>www.example.com</literal>,
2117 <literal>example.com</literal> and <literal>foo.bar.baz.example.com</literal>.
2118 Note that it wouldn't match if the second-level domain was <literal>another-example</literal>.
2123 <term><literal>www.</literal></term>
2126 matches any domain that <emphasis>STARTS</emphasis> with
2127 <literal>www.</literal> (It also matches the domain
2128 <literal>www</literal> but most of the time that doesn't matter.)
2133 <term><literal>.example.</literal></term>
2136 matches any domain that <emphasis>CONTAINS</emphasis> <literal>.example.</literal>.
2137 And, by the way, also included would be any files or documents that exist
2138 within that domain since no path limitations are specified. (Correctly
2139 speaking: It matches any FQDN that contains <literal>example</literal> as
2140 a domain.) This might be <literal>www.example.com</literal>,
2141 <literal>news.example.de</literal>, or
2142 <literal>www.example.net/cgi/testing.pl</literal> for instance. All these
2150 Additionally, there are wild-cards that you can use in the domain names
2151 themselves. These work similarly to shell globbing type wild-cards:
2152 <quote>*</quote> represents zero or more arbitrary characters (this is
2154 <ulink url="http://en.wikipedia.org/wiki/Regular_expressions"><quote>Regular
2155 Expression</quote></ulink> based syntax of <quote>.*</quote>),
2156 <quote>?</quote> represents any single character (this is equivalent to the
2157 regular expression syntax of a simple <quote>.</quote>), and you can define
2158 <quote>character classes</quote> in square brackets which is similar to
2159 the same regular expression technique. All of this can be freely mixed:
2164 <term><literal>ad*.example.com</literal></term>
2167 matches <quote>adserver.example.com</quote>,
2168 <quote>ads.example.com</quote>, etc but not <quote>sfads.example.com</quote>
2173 <term><literal>*ad*.example.com</literal></term>
2176 matches all of the above, and then some.
2181 <term><literal>.?pix.com</literal></term>
2184 matches <literal>www.ipix.com</literal>,
2185 <literal>pictures.epix.com</literal>, <literal>a.b.c.d.e.upix.com</literal> etc.
2190 <term><literal>www[1-9a-ez].example.c*</literal></term>
2193 matches <literal>www1.example.com</literal>,
2194 <literal>www4.example.cc</literal>, <literal>wwwd.example.cy</literal>,
2195 <literal>wwwz.example.com</literal> etc., but <emphasis>not</emphasis>
2196 <literal>wwww.example.com</literal>.
2203 While flexible, this is not the sophistication of full regular expression based syntax.
2208 <!-- ~ End section ~ -->
2211 <!-- ~~~~~ New section ~~~~~ -->
2212 <sect3 id="path-pattern"><title>The Path Pattern</title>
2215 <application>Privoxy</application> uses <quote>modern</quote> POSIX 1003.2
2216 <ulink url="http://en.wikipedia.org/wiki/Regular_expressions"><quote>Regular
2217 Expressions</quote></ulink> for matching the path portion (after the slash),
2218 and is thus more flexible.
2222 There is an <link linkend="regex">Appendix</link> with a brief quick-start into regular
2223 expressions, you also might want to have a look at your operating system's documentation
2224 on regular expressions (try <literal>man re_format</literal>).
2228 Note that the path pattern is automatically left-anchored at the <quote>/</quote>,
2229 i.e. it matches as if it would start with a <quote>^</quote> (regular expression speak
2230 for the beginning of a line).
2234 Please also note that matching in the path is <emphasis>CASE INSENSITIVE</emphasis>
2235 by default, but you can switch to case sensitive at any point in the pattern by using the
2236 <quote>(?-i)</quote> switch: <literal>www.example.com/(?-i)PaTtErN.*</literal> will match
2237 only documents whose path starts with <literal>PaTtErN</literal> in
2238 <emphasis>exactly</emphasis> this capitalization.
2243 <term><literal>.example.com/.*</literal></term>
2246 Is equivalent to just <quote>.example.com</quote>, since any documents
2247 within that domain are matched with or without the <quote>.*</quote>
2248 regular expression. This is redundant
2253 <term><literal>.example.com/.*/index.html$</literal></term>
2256 Will match any page in the domain of <quote>example.com</quote> that is
2257 named <quote>index.html</quote>, and that is part of some path. For
2258 example, it matches <quote>www.example.com/testing/index.html</quote> but
2259 NOT <quote>www.example.com/index.html</quote> because the regular
2260 expression called for at least two <quote>/'s</quote>, thus the path
2261 requirement. It also would match
2262 <quote>www.example.com/testing/index_html</quote>, because of the
2263 special meta-character <quote>.</quote>.
2268 <term><literal>.example.com/(.*/)?index\.html$</literal></term>
2271 This regular expression is conditional so it will match any page
2272 named <quote>index.html</quote> regardless of path which in this case can
2273 have one or more <quote>/'s</quote>. And this one must contain exactly
2274 <quote>.html</quote> (and end with that!).
2279 <term><literal>.example.com/(.*/)(ads|banners?|junk)</literal></term>
2282 This regular expression will match any path of <quote>example.com</quote>
2283 that contains any of the words <quote>ads</quote>, <quote>banner</quote>,
2284 <quote>banners</quote> (because of the <quote>?</quote>) or <quote>junk</quote>.
2285 The path does not have to end in these words, just contain them.
2286 The path has to contain at least two slashes (including the one at the beginning).
2291 <term><literal>.example.com/(.*/)(ads|banners?|junk)/.*\.(jpe?g|gif|png)$</literal></term>
2294 This is very much the same as above, except now it must end in either
2295 <quote>.jpg</quote>, <quote>.jpeg</quote>, <quote>.gif</quote> or <quote>.png</quote>. So this
2296 one is limited to common image formats.
2303 There are many, many good examples to be found in <filename>default.action</filename>,
2304 and more tutorials below in <link linkend="regex">Appendix on regular expressions</link>.
2309 <!-- ~ End section ~ -->
2312 <!-- ~~~~~ New section ~~~~~ -->
2313 <sect3 id="tag-pattern"><title>The Request Tag Pattern</title>
2316 Request tag patterns are used to change the applying actions based on the
2317 request's tags. Tags can be created based on HTTP headers with either
2318 the <link linkend="CLIENT-HEADER-TAGGER">client-header-tagger</link>
2319 or the <link linkend="SERVER-HEADER-TAGGER">server-header-tagger</link> action.
2323 Request tag patterns have to start with <quote>TAG:</quote>, so &my-app;
2324 can tell them apart from other patterns. Everything after the colon
2325 including white space, is interpreted as a regular expression with
2326 path pattern syntax, except that tag patterns aren't left-anchored
2327 automatically (&my-app; doesn't silently add a <quote>^</quote>,
2328 you have to do it yourself if you need it).
2332 To match all requests that are tagged with <quote>foo</quote>
2333 your pattern line should be <quote>TAG:^foo$</quote>,
2334 <quote>TAG:foo</quote> would work as well, but it would also
2335 match requests whose tags contain <quote>foo</quote> somewhere.
2336 <quote>TAG: foo</quote> wouldn't work as it requires white space.
2340 Sections can contain URL and request tag patterns at the same time,
2341 but request tag patterns are checked after the URL patterns and thus
2342 always overrule them, even if they are located before the URL patterns.
2346 Once a new request tag is added, Privoxy checks right away if it's matched by one
2347 of the request tag patterns and updates the action settings accordingly. As a result
2348 request tags can be used to activate other tagger actions, as long as these other
2349 taggers look for headers that haven't already be parsed.
2353 For example you could tag client requests which use the
2354 <literal>POST</literal> method,
2355 then use this tag to activate another tagger that adds a tag if cookies
2356 are sent, and then use a block action based on the cookie tag. This allows
2357 the outcome of one action, to be input into a subsequent action. However if
2358 you'd reverse the position of the described taggers, and activated the
2359 method tagger based on the cookie tagger, no method tags would be created.
2360 The method tagger would look for the request line, but at the time
2361 the cookie tag is created, the request line has already been parsed.
2365 While this is a limitation you should be aware of, this kind of
2366 indirection is seldom needed anyway and even the example doesn't
2367 make too much sense.
2372 <!-- ~~~~~ New section ~~~~~ -->
2373 <sect3 id="negative-tag-patterns"><title>The Negative Request Tag Patterns</title>
2376 To match requests that do not have a certain request tag, specify a negative tag pattern
2377 by prefixing the tag pattern line with either <quote>NO-REQUEST-TAG:</quote>
2378 or <quote>NO-RESPONSE-TAG:</quote> instead of <quote>TAG:</quote>.
2382 Negative request tag patterns created with <quote>NO-REQUEST-TAG:</quote> are checked
2383 after all client headers are scanned, the ones created with <quote>NO-RESPONSE-TAG:</quote>
2384 are checked after all server headers are scanned. In both cases all the created
2385 tags are considered.
2389 <!-- ~~~~~ New section ~~~~~ -->
2390 <sect3 id="client-tag-pattern"><title>The Client Tag Pattern</title>
2392 <!-- XXX: This section contains duplicates content from the
2393 client-specific-tag documentation. -->
2397 This is an experimental feature. The syntax is likely to change in future versions.
2402 Client tag patterns are not set based on HTTP headers but based on
2403 the client's IP address. Users can enable them themselves, but the
2404 Privoxy admin controls which tags are available and what their effect
2409 After a client-specific tag has been defined with the
2410 <link linkend="client-specific-tag">client-specific-tag</link>,
2411 directive, action sections can be activated based on the tag by using a
2412 CLIENT-TAG pattern. The CLIENT-TAG pattern is evaluated at the same priority
2413 as URL patterns, as a result the last matching pattern wins. Tags that
2414 are created based on client or server headers are evaluated later on
2415 and can overrule CLIENT-TAG and URL patterns!
2418 The tag is set for all requests that come from clients that requested
2419 it to be set. Note that "clients" are differentiated by IP address,
2420 if the IP address changes the tag has to be requested again.
2423 Clients can request tags to be set by using the CGI interface <ulink
2424 url="http://config.privoxy.org/client-tags">http://config.privoxy.org/client-tags</ulink>.
2433 # If the admin defined the client-specific-tag circumvent-blocks,
2434 # and the request comes from a client that previously requested
2435 # the tag to be set, overrule all previous +block actions that
2436 # are enabled based on URL to CLIENT-TAG patterns.
2438 CLIENT-TAG:^circumvent-blocks$
2440 # This section is not overruled because it's located after
2442 {+block{Nobody is supposed to request this.}}
2443 example.org/blocked-example-page</screen>
2450 <!-- ~ End section ~ -->
2453 <!-- ~~~~~ New section ~~~~~ -->
2455 <sect2 id="actions">
2456 <title>Actions</title>
2458 All actions are disabled by default, until they are explicitly enabled
2459 somewhere in an actions file. Actions are turned on if preceded with a
2460 <quote>+</quote>, and turned off if preceded with a <quote>-</quote>. So a
2461 <literal>+action</literal> means <quote>do that action</quote>, e.g.
2462 <literal>+block</literal> means <quote>please block URLs that match the
2463 following patterns</quote>, and <literal>-block</literal> means <quote>don't
2464 block URLs that match the following patterns, even if <literal>+block</literal>
2465 previously applied.</quote>
2469 Again, actions are invoked by placing them on a line, enclosed in curly braces and
2470 separated by whitespace, like in
2471 <literal>{+some-action -some-other-action{some-parameter}}</literal>,
2472 followed by a list of URL patterns, one per line, to which they apply.
2473 Together, the actions line and the following pattern lines make up a section
2474 of the actions file.
2478 Actions fall into three categories:
2485 Boolean, i.e the action can only be <quote>enabled</quote> or
2486 <quote>disabled</quote>. Syntax:
2490 +<replaceable class="function">name</replaceable> # enable action <replaceable class="parameter">name</replaceable>
2491 -<replaceable class="function">name</replaceable> # disable action <replaceable class="parameter">name</replaceable></screen>
2494 Example: <literal>+handle-as-image</literal>
2501 Parameterized, where some value is required in order to enable this type of action.
2506 +<replaceable class="function">name</replaceable>{<replaceable class="parameter">param</replaceable>} # enable action and set parameter to <replaceable class="parameter">param</replaceable>,
2507 # overwriting parameter from previous match if necessary
2508 -<replaceable class="function">name</replaceable> # disable action. The parameter can be omitted</screen>
2511 Note that if the URL matches multiple positive forms of a parameterized action,
2512 the last match wins, i.e. the params from earlier matches are simply ignored.
2515 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>
2521 Multi-value. These look exactly like parameterized actions,
2522 but they behave differently: If the action applies multiple times to the
2523 same URL, but with different parameters, <emphasis>all</emphasis> the parameters
2524 from <emphasis>all</emphasis> matches are remembered. This is used for actions
2525 that can be executed for the same request repeatedly, like adding multiple
2526 headers, or filtering through multiple filters. Syntax:
2530 +<replaceable class="function">name</replaceable>{<replaceable class="parameter">param</replaceable>} # enable action and add <replaceable class="parameter">param</replaceable> to the list of parameters
2531 -<replaceable class="function">name</replaceable>{<replaceable class="parameter">param</replaceable>} # remove the parameter <replaceable class="parameter">param</replaceable> from the list of parameters
2532 # If it was the last one left, disable the action.
2533 <replaceable class="parameter">-name</replaceable> # disable this action completely and remove all parameters from the list</screen>
2536 Examples: <literal>+add-header{X-Fun-Header: Some text}</literal> and
2537 <literal>+filter{html-annoyances}</literal>
2545 If nothing is specified in any actions file, no <quote>actions</quote> are
2546 taken. So in this case <application>Privoxy</application> would just be a
2547 normal, non-blocking, non-filtering proxy. You must specifically enable the
2548 privacy and blocking features you need (although the provided default actions
2549 files will give a good starting point).
2553 Later defined action sections always over-ride earlier ones of the same type.
2554 So exceptions to any rules you make, should come in the latter part of the file (or
2555 in a file that is processed later when using multiple actions files such
2556 as <filename>user.action</filename>). For multi-valued actions, the actions
2557 are applied in the order they are specified. Actions files are processed in
2558 the order they are defined in <filename>config</filename> (the default
2559 installation has three actions files). It also quite possible for any given
2560 URL to match more than one <quote>pattern</quote> (because of wildcards and
2561 regular expressions), and thus to trigger more than one set of actions! Last
2565 <!-- start actions listing -->
2567 The list of valid <application>Privoxy</application> actions are:
2571 <!-- ********************************************************** -->
2572 <!-- Please note the below defined actions use id's that are -->
2573 <!-- probably linked from other places, so please don't change. -->
2575 <!-- ********************************************************** -->
2578 <!-- ~~~~~ New section ~~~~~ -->
2580 <sect3 renderas="sect4" id="add-header">
2581 <title>add-header</title>
2585 <term>Typical use:</term>
2587 <para>Confuse log analysis, custom applications</para>
2592 <term>Effect:</term>
2595 Sends a user defined HTTP header to the web server.
2602 <!-- boolean, parameterized, Multi-value -->
2604 <para>Multi-value.</para>
2609 <term>Parameter:</term>
2612 Any string value is possible. Validity of the defined HTTP headers is not checked.
2613 It is recommended that you use the <quote><literal>X-</literal></quote> prefix
2623 This action may be specified multiple times, in order to define multiple
2624 headers. This is rarely needed for the typical user. If you don't know what
2625 <quote>HTTP headers</quote> are, you definitely don't need to worry about this
2629 Headers added by this action are not modified by other actions.
2635 <term>Example usage:</term>
2638 <screen># Add a DNT ("Do not track") header to all requests,
2639 # event to those that already have one.
2641 # This is just an example, not a recommendation.
2643 # There is no reason to believe that user-tracking websites care
2644 # about the DNT header and depending on the User-Agent, adding the
2645 # header may make user-tracking easier.
2646 {+add-header{DNT: 1}}
2655 <!-- ~~~~~ New section ~~~~~ -->
2656 <sect3 renderas="sect4" id="block">
2657 <title>block</title>
2661 <term>Typical use:</term>
2663 <para>Block ads or other unwanted content</para>
2668 <term>Effect:</term>
2671 Requests for URLs to which this action applies are blocked, i.e. the
2672 requests are trapped by &my-app; and the requested URL is never retrieved,
2673 but is answered locally with a substitute page or image, as determined by
2675 linkend="handle-as-image">handle-as-image</link></literal>,
2677 linkend="set-image-blocker">set-image-blocker</link></literal>, and
2679 linkend="handle-as-empty-document">handle-as-empty-document</link></literal> actions.
2687 <!-- boolean, parameterized, Multi-value -->
2689 <para>Parameterized.</para>
2694 <term>Parameter:</term>
2696 <para>A block reason that should be given to the user.</para>
2704 <application>Privoxy</application> sends a special <quote>BLOCKED</quote> page
2705 for requests to blocked pages. This page contains the block reason given as
2706 parameter, a link to find out why the block action applies, and a click-through
2707 to the blocked content (the latter only if the force feature is available and
2711 A very important exception occurs if <emphasis>both</emphasis>
2712 <literal>block</literal> and <literal><link linkend="handle-as-image">handle-as-image</link></literal>,
2713 apply to the same request: it will then be replaced by an image. If
2714 <literal><link linkend="set-image-blocker">set-image-blocker</link></literal>
2715 (see below) also applies, the type of image will be determined by its parameter,
2716 if not, the standard checkerboard pattern is sent.
2719 It is important to understand this process, in order
2720 to understand how <application>Privoxy</application> deals with
2721 ads and other unwanted content. Blocking is a core feature, and one
2722 upon which various other features depend.
2725 The <literal><link linkend="filter">filter</link></literal>
2726 action can perform a very similar task, by <quote>blocking</quote>
2727 banner images and other content through rewriting the relevant URLs in the
2728 document's HTML source, so they don't get requested in the first place.
2729 Note that this is a totally different technique, and it's easy to confuse the two.
2735 <term>Example usage (section):</term>
2738 <screen>{+block{No nasty stuff for you.}}
2739 # Block and replace with "blocked" page
2740 .nasty-stuff.example.com
2742 {+block{Doubleclick banners.} +handle-as-image}
2743 # Block and replace with image
2747 {+block{Layered ads.} +handle-as-empty-document}
2748 # Block and then ignore
2749 adserver.example.net/.*\.js$</screen>
2759 <!-- ~~~~~ New section ~~~~~ -->
2760 <sect3 renderas="sect4" id="change-x-forwarded-for">
2761 <title>change-x-forwarded-for</title>
2765 <term>Typical use:</term>
2767 <para>Improve privacy by not forwarding the source of the request in the HTTP headers.</para>
2772 <term>Effect:</term>
2775 Deletes the <quote>X-Forwarded-For:</quote> HTTP header from the client request,
2783 <!-- Boolean, Parameterized, Multi-value -->
2785 <para>Parameterized.</para>
2790 <term>Parameter:</term>
2794 <para><quote>block</quote> to delete the header.</para>
2798 <quote>add</quote> to create the header (or append
2799 the client's IP address to an already existing one).
2810 It is safe and recommended to use <literal>block</literal>.
2813 Forwarding the source address of the request may make
2814 sense in some multi-user setups but is also a privacy risk.
2819 <term>Example usage:</term>
2822 <screen>+change-x-forwarded-for{block}</screen>
2829 <!-- ~~~~~ New section ~~~~~ -->
2830 <sect3 renderas="sect4" id="client-header-filter">
2831 <title>client-header-filter</title>
2835 <term>Typical use:</term>
2838 Rewrite or remove single client headers.
2844 <term>Effect:</term>
2847 All client headers to which this action applies are filtered on-the-fly through
2848 the specified regular expression based substitutions.
2855 <!-- boolean, parameterized, Multi-value -->
2857 <para>Multi-value.</para>
2862 <term>Parameter:</term>
2865 The name of a client-header filter, as defined in one of the
2866 <link linkend="filter-file">filter files</link>.
2875 Client-header filters are applied to each header on its own, not to
2876 all at once. This makes it easier to diagnose problems, but on the downside
2877 you can't write filters that only change header x if header y's value is z.
2878 You can do that by using tags though.
2881 Client-header filters are executed after the other header actions have finished
2882 and use their output as input.
2885 If the request URI gets changed, &my-app; will detect that and use the new
2886 one. This can be used to rewrite the request destination behind the client's
2887 back, for example to specify a Tor exit relay for certain requests.
2890 Please refer to the <link linkend="filter-file">filter file chapter</link>
2891 to learn which client-header filters are available by default, and how to
2899 <term>Example usage (section):</term>
2903 # Hide Tor exit notation in Host and Referer Headers
2904 {+client-header-filter{hide-tor-exit-notation}}
2915 <!-- ~~~~~ New section ~~~~~ -->
2916 <sect3 renderas="sect4" id="client-header-tagger">
2917 <title>client-header-tagger</title>
2921 <term>Typical use:</term>
2924 Block requests based on their headers.
2930 <term>Effect:</term>
2933 Client headers to which this action applies are filtered on-the-fly through
2934 the specified regular expression based substitutions, the result is used as
2942 <!-- boolean, parameterized, Multi-value -->
2944 <para>Multi-value.</para>
2949 <term>Parameter:</term>
2952 The name of a client-header tagger, as defined in one of the
2953 <link linkend="filter-file">filter files</link>.
2962 Client-header taggers are applied to each header on its own,
2963 and as the header isn't modified, each tagger <quote>sees</quote>
2967 Client-header taggers are the first actions that are executed
2968 and their tags can be used to control every other action.
2974 <term>Example usage (section):</term>
2978 # Tag every request with the User-Agent header
2979 {+client-header-tagger{user-agent}}
2982 # Tagging itself doesn't change the action
2983 # settings, sections with TAG patterns do:
2985 # If it's a download agent, use a different forwarding proxy,
2986 # show the real User-Agent and make sure resume works.
2987 {+forward-override{forward-socks5 10.0.0.2:2222 .} \
2988 -hide-if-modified-since \
2989 -overwrite-last-modified \
2994 TAG:^User-Agent: NetBSD-ftp/
2995 TAG:^User-Agent: Novell ZYPP Installer
2996 TAG:^User-Agent: RPM APT-HTTP/
2997 TAG:^User-Agent: fetch libfetch/
2998 TAG:^User-Agent: Ubuntu APT-HTTP/
2999 TAG:^User-Agent: MPlayer/
3004 # Tag all requests with the Range header set
3005 {+client-header-tagger{range-requests}}
3008 # Disable filtering for the tagged requests.
3010 # With filtering enabled Privoxy would remove the Range headers
3011 # to be able to filter the whole response. The downside is that
3012 # it prevents clients from resuming downloads or skipping over
3013 # parts of multimedia files.
3014 {-filter -deanimate-gifs}
3020 # Tag all requests with the client IP address
3022 # (Technically the client IP address isn't included in the
3023 # client headers but client-header taggers can set it anyway.
3024 # For details see the tagger in default.filter)
3025 {+client-header-tagger{client-ip-address}}
3028 # Change forwarding settings for requests coming from address 10.0.0.1
3029 {+forward-override{forward-socks5 127.0.1.2:2222 .}}
3030 TAG:^IP-ADDRESS: 10\.0\.0\.1$
3040 <!-- ~~~~~ New section ~~~~~ -->
3041 <sect3 renderas="sect4" id="content-type-overwrite">
3042 <title>content-type-overwrite</title>
3046 <term>Typical use:</term>
3048 <para>Stop useless download menus from popping up, or change the browser's rendering mode</para>
3053 <term>Effect:</term>
3056 Replaces the <quote>Content-Type:</quote> HTTP server header.
3063 <!-- Boolean, Parameterized, Multi-value -->
3065 <para>Parameterized.</para>
3070 <term>Parameter:</term>
3082 The <quote>Content-Type:</quote> HTTP server header is used by the
3083 browser to decide what to do with the document. The value of this
3084 header can cause the browser to open a download menu instead of
3085 displaying the document by itself, even if the document's format is
3086 supported by the browser.
3089 The declared content type can also affect which rendering mode
3090 the browser chooses. If XHTML is delivered as <quote>text/html</quote>,
3091 many browsers treat it as yet another broken HTML document.
3092 If it is send as <quote>application/xml</quote>, browsers with
3093 XHTML support will only display it, if the syntax is correct.
3096 If you see a web site that proudly uses XHTML buttons, but sets
3097 <quote>Content-Type: text/html</quote>, you can use &my-app;
3098 to overwrite it with <quote>application/xml</quote> and validate
3099 the web master's claim inside your XHTML-supporting browser.
3100 If the syntax is incorrect, the browser will complain loudly.
3103 You can also go the opposite direction: if your browser prints
3104 error messages instead of rendering a document falsely declared
3105 as XHTML, you can overwrite the content type with
3106 <quote>text/html</quote> and have it rendered as broken HTML document.
3109 By default <literal>content-type-overwrite</literal> only replaces
3110 <quote>Content-Type:</quote> headers that look like some kind of text.
3111 If you want to overwrite it unconditionally, you have to combine it with
3112 <literal><link linkend="force-text-mode">force-text-mode</link></literal>.
3113 This limitation exists for a reason, think twice before circumventing it.
3116 Most of the time it's easier to replace this action with a custom
3117 <literal><link linkend="server-header-filter">server-header filter</link></literal>.
3118 It allows you to activate it for every document of a certain site and it will still
3119 only replace the content types you aimed at.
3122 Of course you can apply <literal>content-type-overwrite</literal>
3123 to a whole site and then make URL based exceptions, but it's a lot
3124 more work to get the same precision.
3130 <term>Example usage (sections):</term>
3133 <screen># Check if www.example.net/ really uses valid XHTML
3134 { +content-type-overwrite{application/xml} }
3137 # but leave the content type unmodified if the URL looks like a style sheet
3138 {-content-type-overwrite}
3139 www.example.net/.*\.css$
3140 www.example.net/.*style
3149 <!-- ~~~~~ New section ~~~~~ -->
3150 <sect3 renderas="sect4" id="crunch-client-header">
3154 <title>crunch-client-header</title>
3158 <term>Typical use:</term>
3160 <para>Remove a client header <application>Privoxy</application> has no dedicated action for.</para>
3165 <term>Effect:</term>
3168 Deletes every header sent by the client that contains the string the user supplied as parameter.
3175 <!-- Boolean, Parameterized, Multi-value -->
3177 <para>Parameterized.</para>
3182 <term>Parameter:</term>
3194 This action allows you to block client headers for which no dedicated
3195 <application>Privoxy</application> action exists.
3196 <application>Privoxy</application> will remove every client header that
3197 contains the string you supplied as parameter.
3200 Regular expressions are <emphasis>not supported</emphasis> and you can't
3201 use this action to block different headers in the same request, unless
3202 they contain the same string.
3205 <literal>crunch-client-header</literal> is only meant for quick tests.
3206 If you have to block several different headers, or only want to modify
3207 parts of them, you should use a
3208 <literal><link linkend="client-header-filter">client-header filter</link></literal>.
3212 Don't block any header without understanding the consequences.
3219 <term>Example usage (section):</term>
3222 <screen># Block the non-existent "Privacy-Violation:" client header
3223 { +crunch-client-header{Privacy-Violation:} }
3233 <!-- ~~~~~ New section ~~~~~ -->
3234 <sect3 renderas="sect4" id="crunch-if-none-match">
3235 <title>crunch-if-none-match</title>
3241 <term>Typical use:</term>
3243 <para>Prevent yet another way to track the user's steps between sessions.</para>
3248 <term>Effect:</term>
3251 Deletes the <quote>If-None-Match:</quote> HTTP client header.
3258 <!-- Boolean, Parameterized, Multi-value -->
3260 <para>Boolean.</para>
3265 <term>Parameter:</term>
3277 Removing the <quote>If-None-Match:</quote> HTTP client header
3278 is useful for filter testing, where you want to force a real
3279 reload instead of getting status code <quote>304</quote> which
3280 would cause the browser to use a cached copy of the page.
3283 It is also useful to make sure the header isn't used as a cookie
3284 replacement (unlikely but possible).
3287 Blocking the <quote>If-None-Match:</quote> header shouldn't cause any
3288 caching problems, as long as the <quote>If-Modified-Since:</quote> header
3289 isn't blocked or missing as well.
3292 It is recommended to use this action together with
3293 <literal><link linkend="hide-if-modified-since">hide-if-modified-since</link></literal>
3295 <literal><link linkend="overwrite-last-modified">overwrite-last-modified</link></literal>.
3301 <term>Example usage (section):</term>
3304 <screen># Let the browser revalidate cached documents but don't
3305 # allow the server to use the revalidation headers for user tracking.
3306 {+hide-if-modified-since{-60} \
3307 +overwrite-last-modified{randomize} \
3308 +crunch-if-none-match}
3317 <!-- ~~~~~ New section ~~~~~ -->
3318 <sect3 renderas="sect4" id="crunch-incoming-cookies">
3319 <title>crunch-incoming-cookies</title>
3323 <term>Typical use:</term>
3326 Prevent the web server from setting HTTP cookies on your system
3332 <term>Effect:</term>
3335 Deletes any <quote>Set-Cookie:</quote> HTTP headers from server replies.
3342 <!-- Boolean, Parameterized, Multi-value -->
3344 <para>Boolean.</para>
3349 <term>Parameter:</term>
3361 This action is only concerned with <emphasis>incoming</emphasis> HTTP cookies. For
3362 <emphasis>outgoing</emphasis> HTTP cookies, use
3363 <literal><link linkend="crunch-outgoing-cookies">crunch-outgoing-cookies</link></literal>.
3364 Use <emphasis>both</emphasis> to disable HTTP cookies completely.
3367 It makes <emphasis>no sense at all</emphasis> to use this action in conjunction
3368 with the <literal><link linkend="session-cookies-only">session-cookies-only</link></literal> action,
3369 since it would prevent the session cookies from being set. See also
3370 <literal><link linkend="filter-content-cookies">filter-content-cookies</link></literal>.
3376 <term>Example usage:</term>
3379 <screen>+crunch-incoming-cookies</screen>
3387 <!-- ~~~~~ New section ~~~~~ -->
3388 <sect3 renderas="sect4" id="crunch-server-header">
3389 <title>crunch-server-header</title>
3395 <term>Typical use:</term>
3397 <para>Remove a server header <application>Privoxy</application> has no dedicated action for.</para>
3402 <term>Effect:</term>
3405 Deletes every header sent by the server that contains the string the user supplied as parameter.
3412 <!-- Boolean, Parameterized, Multi-value -->
3414 <para>Parameterized.</para>
3419 <term>Parameter:</term>
3431 This action allows you to block server headers for which no dedicated
3432 <application>Privoxy</application> action exists. <application>Privoxy</application>
3433 will remove every server header that contains the string you supplied as parameter.
3436 Regular expressions are <emphasis>not supported</emphasis> and you can't
3437 use this action to block different headers in the same request, unless
3438 they contain the same string.
3441 <literal>crunch-server-header</literal> is only meant for quick tests.
3442 If you have to block several different headers, or only want to modify
3443 parts of them, you should use a custom
3444 <literal><link linkend="server-header-filter">server-header filter</link></literal>.
3448 Don't block any header without understanding the consequences.
3455 <term>Example usage (section):</term>
3458 <screen># Crunch server headers that try to prevent caching
3459 { +crunch-server-header{no-cache} }
3468 <!-- ~~~~~ New section ~~~~~ -->
3469 <sect3 renderas="sect4" id="crunch-outgoing-cookies">
3470 <title>crunch-outgoing-cookies</title>
3474 <term>Typical use:</term>
3477 Prevent the web server from reading any HTTP cookies from your system
3483 <term>Effect:</term>
3486 Deletes any <quote>Cookie:</quote> HTTP headers from client requests.
3493 <!-- Boolean, Parameterized, Multi-value -->
3495 <para>Boolean.</para>
3500 <term>Parameter:</term>
3512 This action is only concerned with <emphasis>outgoing</emphasis> HTTP cookies. For
3513 <emphasis>incoming</emphasis> HTTP cookies, use
3514 <literal><link linkend="crunch-incoming-cookies">crunch-incoming-cookies</link></literal>.
3515 Use <emphasis>both</emphasis> to disable HTTP cookies completely.
3518 It makes <emphasis>no sense at all</emphasis> to use this action in conjunction
3519 with the <literal><link linkend="session-cookies-only">session-cookies-only</link></literal> action,
3520 since it would prevent the session cookies from being read.
3526 <term>Example usage:</term>
3529 <screen>+crunch-outgoing-cookies</screen>
3538 <!-- ~~~~~ New section ~~~~~ -->
3539 <sect3 renderas="sect4" id="deanimate-gifs">
3540 <title>deanimate-gifs</title>
3544 <term>Typical use:</term>
3546 <para>Stop those annoying, distracting animated GIF images.</para>
3551 <term>Effect:</term>
3554 De-animate GIF animations, i.e. reduce them to their first or last image.
3561 <!-- boolean, parameterized, Multi-value -->
3563 <para>Parameterized.</para>
3568 <term>Parameter:</term>
3571 <quote>last</quote> or <quote>first</quote>
3580 This will also shrink the images considerably (in bytes, not pixels!). If
3581 the option <quote>first</quote> is given, the first frame of the animation
3582 is used as the replacement. If <quote>last</quote> is given, the last
3583 frame of the animation is used instead, which probably makes more sense for
3584 most banner animations, but also has the risk of not showing the entire
3585 last frame (if it is only a delta to an earlier frame).
3588 You can safely use this action with patterns that will also match non-GIF
3589 objects, because no attempt will be made at anything that doesn't look like
3596 <term>Example usage:</term>
3599 <screen>+deanimate-gifs{last}</screen>
3606 <!-- ~~~~~ New section ~~~~~ -->
3607 <sect3 renderas="sect4" id="downgrade-http-version">
3608 <title>downgrade-http-version</title>
3612 <term>Typical use:</term>
3614 <para>Work around (very rare) problems with HTTP/1.1</para>
3619 <term>Effect:</term>
3622 Downgrades HTTP/1.1 client requests and server replies to HTTP/1.0.
3629 <!-- boolean, parameterized, Multi-value -->
3631 <para>Boolean.</para>
3636 <term>Parameter:</term>
3648 This is a left-over from the time when <application>Privoxy</application>
3649 didn't support important HTTP/1.1 features well. It is left here for the
3650 unlikely case that you experience HTTP/1.1-related problems with some server
3654 Note that enabling this action is only a workaround. It should not
3655 be enabled for sites that work without it. While it shouldn't break
3656 any pages, it has an (usually negative) performance impact.
3659 If you come across a site where enabling this action helps, please report it,
3660 so the cause of the problem can be analyzed. If the problem turns out to be
3661 caused by a bug in <application>Privoxy</application> it should be
3662 fixed so the following release works without the work around.
3668 <term>Example usage (section):</term>
3671 <screen>{+downgrade-http-version}
3672 problem-host.example.com</screen>
3680 <!-- ~~~~~ New section ~~~~~ -->
3681 <sect3 renderas="sect4" id="external-filter">
3682 <title>external-filter</title>
3686 <term>Typical use:</term>
3688 <para>Modify content using a programming language of your choice.</para>
3693 <term>Effect:</term>
3696 All instances of text-based type, most notably HTML and JavaScript, to which
3697 this action applies, can be filtered on-the-fly through the specified external
3699 By default plain text documents are exempted from filtering, because web
3700 servers often use the <literal>text/plain</literal> MIME type for all files
3701 whose type they don't know.)
3708 <!-- boolean, parameterized, Multi-value -->
3710 <para>Multi-value.</para>
3715 <term>Parameter:</term>
3718 The name of an external content filter, as defined in the
3719 <link linkend="filter-file">filter file</link>.
3720 External filters can be defined in one or more files as defined by the
3721 <literal><link linkend="filterfile">filterfile</link></literal>
3722 option in the <link linkend="config">config file</link>.
3725 When used in its negative form,
3726 and without parameters, <emphasis>all</emphasis> filtering with external
3727 filters is completely disabled.
3736 External filters are scripts or programs that can modify the content in
3737 case common <literal><link linkend="filter">filters</link></literal>
3738 aren't powerful enough. With the exception that this action doesn't
3739 use pcrs-based filters, the notes in the
3740 <literal><link linkend="filter">filter</link></literal> section apply.
3744 Currently external filters are executed with &my-app;'s privileges.
3745 Only use external filters you understand and trust.
3749 This feature is experimental, the <literal><link
3750 linkend="external-filter-syntax">syntax</link></literal>
3751 may change in the future.
3758 <term>Example usage:</term>
3761 <screen>+external-filter{fancy-filter}</screen>
3768 <!-- ~~~~~ New section ~~~~~ -->
3769 <sect3 renderas="sect4" id="fast-redirects">
3770 <title>fast-redirects</title>
3774 <term>Typical use:</term>
3776 <para>Fool some click-tracking scripts and speed up indirect links.</para>
3781 <term>Effect:</term>
3784 Detects redirection URLs and redirects the browser without contacting
3785 the redirection server first.
3792 <!-- boolean, parameterized, Multi-value -->
3794 <para>Parameterized.</para>
3799 <term>Parameter:</term>
3804 <quote>simple-check</quote> to just search for the string <quote>http://</quote>
3805 to detect redirection URLs.
3810 <quote>check-decoded-url</quote> to decode URLs (if necessary) before searching
3811 for redirection URLs.
3822 Many sites, like yahoo.com, don't just link to other sites. Instead, they
3823 will link to some script on their own servers, giving the destination as a
3824 parameter, which will then redirect you to the final target. URLs
3825 resulting from this scheme typically look like:
3826 <quote>http://www.example.org/click-tracker.cgi?target=http%3a//www.example.net/</quote>.
3829 Sometimes, there are even multiple consecutive redirects encoded in the
3830 URL. These redirections via scripts make your web browsing more traceable,
3831 since the server from which you follow such a link can see where you go
3832 to. Apart from that, valuable bandwidth and time is wasted, while your
3833 browser asks the server for one redirect after the other. Plus, it feeds
3837 This feature is currently not very smart and is scheduled for improvement.
3838 If it is enabled by default, you will have to create some exceptions to
3839 this action. It can lead to failures in several ways:
3842 Not every URLs with other URLs as parameters is evil.
3843 Some sites offer a real service that requires this information to work.
3844 For example a validation service needs to know, which document to validate.
3845 <literal>fast-redirects</literal> assumes that every URL parameter that
3846 looks like another URL is a redirection target, and will always redirect to
3847 the last one. Most of the time the assumption is correct, but if it isn't,
3848 the user gets redirected anyway.
3851 Another failure occurs if the URL contains other parameters after the URL parameter.
3853 <quote>http://www.example.org/?redirect=http%3a//www.example.net/&foo=bar</quote>.
3854 contains the redirection URL <quote>http://www.example.net/</quote>,
3855 followed by another parameter. <literal>fast-redirects</literal> doesn't know that
3856 and will cause a redirect to <quote>http://www.example.net/&foo=bar</quote>.
3857 Depending on the target server configuration, the parameter will be silently ignored
3858 or lead to a <quote>page not found</quote> error. You can prevent this problem by
3859 first using the <literal><link linkend="redirect">redirect</link></literal> action
3860 to remove the last part of the URL, but it requires a little effort.
3863 To detect a redirection URL, <literal>fast-redirects</literal> only
3864 looks for the string <quote>http://</quote>, either in plain text
3865 (invalid but often used) or encoded as <quote>http%3a//</quote>.
3866 Some sites use their own URL encoding scheme, encrypt the address
3867 of the target server or replace it with a database id. In theses cases
3868 <literal>fast-redirects</literal> is fooled and the request reaches the
3869 redirection server where it probably gets logged.
3875 <term>Example usage:</term>
3879 { +fast-redirects{simple-check} }
3882 { +fast-redirects{check-decoded-url} }
3883 another.example.com/testing</screen>
3892 <!-- ~~~~~ New section ~~~~~ -->
3893 <sect3 renderas="sect4" id="filter">
3894 <title>filter</title>
3898 <term>Typical use:</term>
3900 <para>Get rid of HTML and JavaScript annoyances, banner advertisements (by size),
3901 do fun text replacements, add personalized effects, etc.</para>
3906 <term>Effect:</term>
3909 All instances of text-based type, most notably HTML and JavaScript, to which
3910 this action applies, can be filtered on-the-fly through the specified regular
3911 expression based substitutions. (Note: as of version 3.0.3 plain text documents
3912 are exempted from filtering, because web servers often use the
3913 <literal>text/plain</literal> MIME type for all files whose type they don't know.)
3920 <!-- boolean, parameterized, Multi-value -->
3922 <para>Multi-value.</para>
3927 <term>Parameter:</term>
3930 The name of a content filter, as defined in the <link linkend="filter-file">filter file</link>.
3931 Filters can be defined in one or more files as defined by the
3932 <literal><link linkend="filterfile">filterfile</link></literal>
3933 option in the <link linkend="config">config file</link>.
3934 <filename>default.filter</filename> is the collection of filters
3935 supplied by the developers. Locally defined filters should go
3936 in their own file, such as <filename>user.filter</filename>.
3939 When used in its negative form,
3940 and without parameters, <emphasis>all</emphasis> filtering is completely disabled.
3949 For your convenience, there are a number of pre-defined filters available
3950 in the distribution filter file that you can use. See the examples below for
3954 Filtering requires buffering the page content, which may appear to
3955 slow down page rendering since nothing is displayed until all content has
3956 passed the filters. (The total time until the page is completely rendered
3957 doesn't change much, but it may be perceived as slower since the page is
3958 not incrementally displayed.)
3959 This effect will be more noticeable on slower connections.
3962 <quote>Rolling your own</quote>
3963 filters requires a knowledge of
3964 <ulink url="http://en.wikipedia.org/wiki/Regular_expressions"><quote>Regular
3965 Expressions</quote></ulink> and
3966 <ulink url="http://en.wikipedia.org/wiki/Html"><quote>HTML</quote></ulink>.
3967 This is very powerful feature, and potentially very intrusive.
3968 Filters should be used with caution, and where an equivalent
3969 <quote>action</quote> is not available.
3972 The amount of data that can be filtered is limited to the
3973 <literal><link linkend="buffer-limit">buffer-limit</link></literal>
3974 option in the main <link linkend="config">config file</link>. The
3975 default is 4096 KB (4 Megs). Once this limit is exceeded, the buffered
3976 data, and all pending data, is passed through unfiltered.
3979 Inappropriate MIME types, such as zipped files, are not filtered at all.
3980 (Again, only text-based types except plain text). Encrypted SSL data
3981 (from HTTPS servers) cannot be filtered either, since this would violate
3982 the integrity of the secure transaction. In some situations it might
3983 be necessary to protect certain text, like source code, from filtering
3984 by defining appropriate <literal>-filter</literal> exceptions.
3987 Compressed content can't be filtered either, but if &my-app;
3988 is compiled with zlib support and a supported compression algorithm
3989 is used (gzip or deflate), &my-app; can first decompress the content
3993 If you use a &my-app; version without zlib support, but want filtering to work on
3994 as much documents as possible, even those that would normally be sent compressed,
3995 you must use the <literal><link linkend="prevent-compression">prevent-compression</link></literal>
3996 action in conjunction with <literal>filter</literal>.
3999 Content filtering can achieve some of the same effects as the
4000 <literal><link linkend="block">block</link></literal>
4001 action, i.e. it can be used to block ads and banners. But the mechanism
4002 works quite differently. One effective use, is to block ad banners
4003 based on their size (see below), since many of these seem to be somewhat
4007 <link linkend="contact">Feedback</link> with suggestions for new or
4008 improved filters is particularly welcome!
4011 The below list has only the names and a one-line description of each
4012 predefined filter. There are <link linkend="predefined-filters">more
4013 verbose explanations</link> of what these filters do in the <link
4014 linkend="filter-file">filter file chapter</link>.
4020 <term>Example usage (with filters from the distribution <filename>default.filter</filename> file).
4021 See <link linkend="PREDEFINED-FILTERS">the Predefined Filters section</link> for
4022 more explanation on each:</term>
4025 <anchor id="filter-js-annoyances">
4026 <screen>+filter{js-annoyances} # Get rid of particularly annoying JavaScript abuse.</screen>
4029 <anchor id="filter-js-events">
4030 <screen>+filter{js-events} # Kill JavaScript event bindings and timers (Radically destructive! Only for extra nasty sites).</screen>
4033 <anchor id="filter-html-annoyances">
4034 <screen>+filter{html-annoyances} # Get rid of particularly annoying HTML abuse.</screen>
4037 <anchor id="filter-content-cookies">
4038 <screen>+filter{content-cookies} # Kill cookies that come in the HTML or JS content.</screen>
4041 <anchor id="filter-refresh-tags">
4042 <screen>+filter{refresh-tags} # Kill automatic refresh tags if refresh time is larger than 9 seconds.</screen>
4045 <anchor id="filter-unsolicited-popups">
4046 <screen>+filter{unsolicited-popups} # Disable only unsolicited pop-up windows.</screen>
4049 <anchor id="filter-all-popups">
4050 <screen>+filter{all-popups} # Kill all popups in JavaScript and HTML.</screen>
4053 <anchor id="filter-img-reorder">
4054 <screen>+filter{img-reorder} # Reorder attributes in <img> tags to make the banners-by-* filters more effective.</screen>
4057 <anchor id="filter-banners-by-size">
4058 <screen>+filter{banners-by-size} # Kill banners by size.</screen>
4061 <anchor id="filter-banners-by-link">
4062 <screen>+filter{banners-by-link} # Kill banners by their links to known clicktrackers.</screen>
4065 <anchor id="filter-webbugs">
4066 <screen>+filter{webbugs} # Squish WebBugs (1x1 invisible GIFs used for user tracking).</screen>
4069 <anchor id="filter-tiny-textforms">
4070 <screen>+filter{tiny-textforms} # Extend those tiny textareas up to 40x80 and kill the hard wrap.</screen>
4073 <anchor id="filter-jumping-windows">
4074 <screen>+filter{jumping-windows} # Prevent windows from resizing and moving themselves.</screen>
4077 <anchor id="filter-frameset-borders">
4078 <screen>+filter{frameset-borders} # Give frames a border and make them resizable.</screen>
4081 <anchor id="filter-iframes">
4082 <screen>+filter{iframes} # Removes all detected iframes. Should only be enabled for individual sites.</screen>
4085 <anchor id="filter-demoronizer">
4086 <screen>+filter{demoronizer} # Fix MS's non-standard use of standard charsets.</screen>
4089 <anchor id="filter-shockwave-flash">
4090 <screen>+filter{shockwave-flash} # Kill embedded Shockwave Flash objects.</screen>
4093 <anchor id="filter-quicktime-kioskmode">
4094 <screen>+filter{quicktime-kioskmode} # Make Quicktime movies saveable.</screen>
4097 <anchor id="filter-fun">
4098 <screen>+filter{fun} # Text replacements for subversive browsing fun!</screen>
4101 <anchor id="filter-crude-parental">
4102 <screen>+filter{crude-parental} # Crude parental filtering. Note that this filter doesn't work reliably.</screen>
4105 <anchor id="filter-ie-exploits">
4106 <screen>+filter{ie-exploits} # Disable some known Internet Explorer bug exploits.</screen>
4109 <anchor id="filter-site-specifics">
4110 <screen>+filter{site-specifics} # Cure for site-specific problems. Don't apply generally!</screen>
4113 <anchor id="filter-no-ping">
4114 <screen>+filter{no-ping} # Removes non-standard ping attributes in <a> and <area> tags.</screen>
4117 <anchor id="filter-google">
4118 <screen>+filter{google} # CSS-based block for Google text ads. Also removes a width limitation and the toolbar advertisement.</screen>
4121 <anchor id="filter-yahoo">
4122 <screen>+filter{yahoo} # CSS-based block for Yahoo text ads. Also removes a width limitation.</screen>
4125 <anchor id="filter-msn">
4126 <screen>+filter{msn} # CSS-based block for MSN text ads. Also removes tracking URLs and a width limitation.</screen>
4129 <anchor id="filter-blogspot">
4130 <screen>+filter{blogspot} # Cleans up some Blogspot blogs. Read the fine print before using this.</screen>
4138 <!-- ~~~~~ New section ~~~~~ -->
4139 <sect3 renderas="sect4" id="force-text-mode">
4140 <title>force-text-mode</title>
4146 <term>Typical use:</term>
4148 <para>Force <application>Privoxy</application> to treat a document as if it was in some kind of <emphasis>text</emphasis> format. </para>
4153 <term>Effect:</term>
4156 Declares a document as text, even if the <quote>Content-Type:</quote> isn't detected as such.
4163 <!-- Boolean, Parameterized, Multi-value -->
4165 <para>Boolean.</para>
4170 <term>Parameter:</term>
4182 As explained <literal><link linkend="filter">above</link></literal>,
4183 <application>Privoxy</application> tries to only filter files that are
4184 in some kind of text format. The same restrictions apply to
4185 <literal><link linkend="content-type-overwrite">content-type-overwrite</link></literal>.
4186 <literal>force-text-mode</literal> declares a document as text,
4187 without looking at the <quote>Content-Type:</quote> first.
4191 Think twice before activating this action. Filtering binary data
4192 with regular expressions can cause file damage.
4199 <term>Example usage:</term>
4212 <!-- ~~~~~ New section ~~~~~ -->
4213 <sect3 renderas="sect4" id="forward-override">
4214 <title>forward-override</title>
4220 <term>Typical use:</term>
4222 <para>Change the forwarding settings based on User-Agent or request origin</para>
4227 <term>Effect:</term>
4230 Overrules the forward directives in the configuration file.
4237 <!-- Boolean, Parameterized, Multi-value -->
4239 <para>Parameterized.</para>
4244 <term>Parameter:</term>
4248 <para><quote>forward .</quote> to use a direct connection without any additional proxies.</para>
4252 <quote>forward 127.0.0.1:8123</quote> to use the HTTP proxy listening at 127.0.0.1 port 8123.
4257 <quote>forward-socks4a 127.0.0.1:9050 .</quote> to use the socks4a proxy listening at
4258 127.0.0.1 port 9050. Replace <quote>forward-socks4a</quote> with <quote>forward-socks4</quote>
4259 to use a socks4 connection (with local DNS resolution) instead, use <quote>forward-socks5</quote>
4260 for socks5 connections (with remote DNS resolution).
4265 <quote>forward-socks4a 127.0.0.1:9050 proxy.example.org:8000</quote> to use the socks4a proxy
4266 listening at 127.0.0.1 port 9050 to reach the HTTP proxy listening at proxy.example.org port 8000.
4267 Replace <quote>forward-socks4a</quote> with <quote>forward-socks4</quote> to use a socks4 connection
4268 (with local DNS resolution) instead, use <quote>forward-socks5</quote>
4269 for socks5 connections (with remote DNS resolution).
4274 <quote>forward-webserver 127.0.0.1:80</quote> to use the HTTP
4275 server listening at 127.0.0.1 port 80 without adjusting the
4279 This makes it more convenient to use Privoxy to make
4280 existing websites available as onion services as well.
4283 Many websites serve content with hardcoded URLs and
4284 can't be easily adjusted to change the domain based
4285 on the one used by the client.
4288 Putting Privoxy between Tor and the webserver (or an stunnel
4289 that forwards to the webserver) allows to rewrite headers and
4290 content to make client and server happy at the same time.
4293 Using Privoxy for webservers that are only reachable through
4294 onion addresses and whose location is supposed to be secret
4295 is not recommended and should not be necessary anyway.
4306 This action takes parameters similar to the
4307 <link linkend="forwarding">forward</link> directives in the configuration
4308 file, but without the URL pattern. It can be used as replacement, but normally it's only
4309 used in cases where matching based on the request URL isn't sufficient.
4313 Please read the description for the <link linkend="forwarding">forward</link> directives before
4314 using this action. Forwarding to the wrong people will reduce your privacy and increase the
4315 chances of man-in-the-middle attacks.
4318 If the ports are missing or invalid, default values will be used. This might change
4319 in the future and you shouldn't rely on it. Otherwise incorrect syntax causes Privoxy
4320 to exit. Due to design limitations, invalid parameter syntax isn't detected until the
4321 action is used the first time.
4324 Use the <ulink url="http://config.privoxy.org/show-url-info">show-url-info CGI page</ulink>
4325 to verify that your forward settings do what you thought the do.
4332 <term>Example usage:</term>
4336 # Use an ssh tunnel for requests previously tagged as
4337 # <quote>User-Agent: fetch libfetch/2.0</quote> and make sure
4338 # resuming downloads continues to work.
4340 # This way you can continue to use Tor for your normal browsing,
4341 # without overloading the Tor network with your FreeBSD ports updates
4342 # or downloads of bigger files like ISOs.
4344 # Note that HTTP headers are easy to fake and therefore their
4345 # values are as (un)trustworthy as your clients and users.
4346 {+forward-override{forward-socks5 10.0.0.2:2222 .} \
4347 -hide-if-modified-since \
4348 -overwrite-last-modified \
4350 TAG:^User-Agent: fetch libfetch/2\.0$
4359 <!-- ~~~~~ New section ~~~~~ -->
4360 <sect3 renderas="sect4" id="handle-as-empty-document">
4361 <title>handle-as-empty-document</title>
4367 <term>Typical use:</term>
4369 <para>Mark URLs that should be replaced by empty documents <emphasis>if they get blocked</emphasis></para>
4374 <term>Effect:</term>
4377 This action alone doesn't do anything noticeable. It just marks URLs.
4378 If the <literal><link linkend="block">block</link></literal> action <emphasis>also applies</emphasis>,
4379 the presence or absence of this mark decides whether an HTML <quote>BLOCKED</quote>
4380 page, or an empty document will be sent to the client as a substitute for the blocked content.
4381 The <emphasis>empty</emphasis> document isn't literally empty, but actually contains a single space.
4388 <!-- Boolean, Parameterized, Multi-value -->
4390 <para>Boolean.</para>
4395 <term>Parameter:</term>
4407 Some browsers complain about syntax errors if JavaScript documents
4408 are blocked with <application>Privoxy's</application>
4409 default HTML page; this option can be used to silence them.
4410 And of course this action can also be used to eliminate the &my-app;
4411 BLOCKED message in frames.
4414 The content type for the empty document can be specified with
4415 <literal><link linkend="content-type-overwrite">content-type-overwrite{}</link></literal>,
4416 but usually this isn't necessary.
4422 <term>Example usage:</term>
4425 <screen># Block all documents on example.org that end with ".js",
4426 # but send an empty document instead of the usual HTML message.
4427 {+block{Blocked JavaScript} +handle-as-empty-document}
4437 <!-- ~~~~~ New section ~~~~~ -->
4438 <sect3 renderas="sect4" id="handle-as-image">
4439 <title>handle-as-image</title>
4443 <term>Typical use:</term>
4445 <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>
4450 <term>Effect:</term>
4453 This action alone doesn't do anything noticeable. It just marks URLs as images.
4454 If the <literal><link linkend="block">block</link></literal> action <emphasis>also applies</emphasis>,
4455 the presence or absence of this mark decides whether an HTML <quote>blocked</quote>
4456 page, or a replacement image (as determined by the <literal><link
4457 linkend="set-image-blocker">set-image-blocker</link></literal> action) will be sent to the
4458 client as a substitute for the blocked content.
4465 <!-- Boolean, Parameterized, Multi-value -->
4467 <para>Boolean.</para>
4472 <term>Parameter:</term>
4484 The below generic example section is actually part of <filename>default.action</filename>.
4485 It marks all URLs with well-known image file name extensions as images and should
4489 Users will probably only want to use the handle-as-image action in conjunction with
4490 <literal><link linkend="block">block</link></literal>, to block sources of banners, whose URLs don't
4491 reflect the file type, like in the second example section.
4494 Note that you cannot treat HTML pages as images in most cases. For instance, (in-line) ad
4495 frames require an HTML page to be sent, or they won't display properly.
4496 Forcing <literal>handle-as-image</literal> in this situation will not replace the
4497 ad frame with an image, but lead to error messages.
4503 <term>Example usage (sections):</term>
4506 <screen># Generic image extensions:
4509 /.*\.(gif|jpg|jpeg|png|bmp|ico)$
4511 # These don't look like images, but they're banners and should be
4512 # blocked as images:
4514 {+block{Nasty banners.} +handle-as-image}
4515 nasty-banner-server.example.com/junk.cgi\?output=trash
4524 <!-- ~~~~~ New section ~~~~~ -->
4525 <sect3 renderas="sect4" id="hide-accept-language">
4526 <title>hide-accept-language</title>
4532 <term>Typical use:</term>
4534 <para>Pretend to use different language settings.</para>
4539 <term>Effect:</term>
4542 Deletes or replaces the <quote>Accept-Language:</quote> HTTP header in client requests.
4549 <!-- Boolean, Parameterized, Multi-value -->
4551 <para>Parameterized.</para>
4556 <term>Parameter:</term>
4559 Keyword: <quote>block</quote>, or any user defined value.
4568 Faking the browser's language settings can be useful to make a
4569 foreign User-Agent set with
4570 <literal><link linkend="hide-user-agent">hide-user-agent</link></literal>
4574 However some sites with content in different languages check the
4575 <quote>Accept-Language:</quote> to decide which one to take by default.
4576 Sometimes it isn't possible to later switch to another language without
4577 changing the <quote>Accept-Language:</quote> header first.
4580 Therefore it's a good idea to either only change the
4581 <quote>Accept-Language:</quote> header to languages you understand,
4582 or to languages that aren't wide spread.
4585 Before setting the <quote>Accept-Language:</quote> header
4586 to a rare language, you should consider that it helps to
4587 make your requests unique and thus easier to trace.
4588 If you don't plan to change this header frequently,
4589 you should stick to a common language.
4595 <term>Example usage (section):</term>
4598 <screen># Pretend to use Canadian language settings.
4599 {+hide-accept-language{en-ca} \
4600 +hide-user-agent{Mozilla/5.0 (X11; U; OpenBSD i386; en-CA; rv:1.8.0.4) Gecko/20060628 Firefox/1.5.0.4} \
4610 <!-- ~~~~~ New section ~~~~~ -->
4611 <sect3 renderas="sect4" id="hide-content-disposition">
4612 <title>hide-content-disposition</title>
4618 <term>Typical use:</term>
4620 <para>Prevent download menus for content you prefer to view inside the browser.</para>
4625 <term>Effect:</term>
4628 Deletes or replaces the <quote>Content-Disposition:</quote> HTTP header set by some servers.
4635 <!-- Boolean, Parameterized, Multi-value -->
4637 <para>Parameterized.</para>
4642 <term>Parameter:</term>
4645 Keyword: <quote>block</quote>, or any user defined value.
4654 Some servers set the <quote>Content-Disposition:</quote> HTTP header for
4655 documents they assume you want to save locally before viewing them.
4656 The <quote>Content-Disposition:</quote> header contains the file name
4657 the browser is supposed to use by default.
4660 In most browsers that understand this header, it makes it impossible to
4661 <emphasis>just view</emphasis> the document, without downloading it first,
4662 even if it's just a simple text file or an image.
4665 Removing the <quote>Content-Disposition:</quote> header helps
4666 to prevent this annoyance, but some browsers additionally check the
4667 <quote>Content-Type:</quote> header, before they decide if they can
4668 display a document without saving it first. In these cases, you have
4669 to change this header as well, before the browser stops displaying
4673 It is also possible to change the server's file name suggestion
4674 to another one, but in most cases it isn't worth the time to set
4678 This action will probably be removed in the future,
4679 use server-header filters instead.
4685 <term>Example usage:</term>
4688 <screen># Disarm the download link in Sourceforge's patch tracker
4690 +content-type-overwrite{text/plain}\
4691 +hide-content-disposition{block} }
4692 .sourceforge.net/tracker/download\.php</screen>
4700 <!-- ~~~~~ New section ~~~~~ -->
4701 <sect3 renderas="sect4" id="hide-if-modified-since">
4702 <title>hide-if-modified-since</title>
4708 <term>Typical use:</term>
4710 <para>Prevent yet another way to track the user's steps between sessions.</para>
4715 <term>Effect:</term>
4718 Deletes the <quote>If-Modified-Since:</quote> HTTP client header or modifies its value.
4725 <!-- Boolean, Parameterized, Multi-value -->
4727 <para>Parameterized.</para>
4732 <term>Parameter:</term>
4735 Keyword: <quote>block</quote>, or a user defined value that specifies a range of hours.
4744 Removing this header is useful for filter testing, where you want to force a real
4745 reload instead of getting status code <quote>304</quote>, which would cause the
4746 browser to use a cached copy of the page.
4749 Instead of removing the header, <literal>hide-if-modified-since</literal> can
4750 also add or subtract a random amount of time to/from the header's value.
4751 You specify a range of minutes where the random factor should be chosen from and
4752 <application>Privoxy</application> does the rest. A negative value means
4753 subtracting, a positive value adding.
4756 Randomizing the value of the <quote>If-Modified-Since:</quote> makes
4757 it less likely that the server can use the time as a cookie replacement,
4758 but you will run into caching problems if the random range is too high.
4761 It is a good idea to only use a small negative value and let
4762 <literal><link linkend="overwrite-last-modified">overwrite-last-modified</link></literal>
4763 handle the greater changes.
4766 It is also recommended to use this action together with
4767 <literal><link linkend="crunch-if-none-match">crunch-if-none-match</link></literal>,
4768 otherwise it's more or less pointless.
4774 <term>Example usage (section):</term>
4777 <screen># Let the browser revalidate but make tracking based on the time less likely.
4778 {+hide-if-modified-since{-60} \
4779 +overwrite-last-modified{randomize} \
4780 +crunch-if-none-match}
4789 <!-- ~~~~~ New section ~~~~~ -->
4790 <sect3 renderas="sect4" id="hide-from-header">
4791 <title>hide-from-header</title>
4795 <term>Typical use:</term>
4797 <para>Keep your (old and ill) browser from telling web servers your email address</para>
4802 <term>Effect:</term>
4805 Deletes any existing <quote>From:</quote> HTTP header, or replaces it with the
4813 <!-- Boolean, Parameterized, Multi-value -->
4815 <para>Parameterized.</para>
4820 <term>Parameter:</term>
4823 Keyword: <quote>block</quote>, or any user defined value.
4832 The keyword <quote>block</quote> will completely remove the header
4833 (not to be confused with the <literal><link linkend="block">block</link></literal>
4837 Alternately, you can specify any value you prefer to be sent to the web
4838 server. If you do, it is a matter of fairness not to use any address that
4839 is actually used by a real person.
4842 This action is rarely needed, as modern web browsers don't send
4843 <quote>From:</quote> headers anymore.
4849 <term>Example usage:</term>
4852 <screen>+hide-from-header{block}</screen> or
4853 <screen>+hide-from-header{spam-me-senseless@sittingduck.example.com}</screen>
4861 <!-- ~~~~~ New section ~~~~~ -->
4862 <sect3 renderas="sect4" id="hide-referrer">
4863 <title>hide-referrer</title>
4864 <anchor id="hide-referer">
4867 <term>Typical use:</term>
4869 <para>Conceal which link you followed to get to a particular site</para>
4874 <term>Effect:</term>
4877 Deletes the <quote>Referer:</quote> (sic) HTTP header from the client request,
4878 or replaces it with a forged one.
4885 <!-- Boolean, Parameterized, Multi-value -->
4887 <para>Parameterized.</para>
4892 <term>Parameter:</term>
4896 <para><quote>conditional-block</quote> to delete the header completely if the host has changed.</para>
4899 <para><quote>conditional-forge</quote> to forge the header if the host has changed.</para>
4902 <para><quote>block</quote> to delete the header unconditionally.</para>
4905 <para><quote>forge</quote> to pretend to be coming from the homepage of the server we are talking to.</para>
4908 <para>Any other string to set a user defined referrer.</para>
4918 <literal>conditional-block</literal> is the only parameter,
4919 that isn't easily detected in the server's log file. If it blocks the
4920 referrer, the request will look like the visitor used a bookmark or
4921 typed in the address directly.
4924 Leaving the referrer unmodified for requests on the same host
4925 allows the server owner to see the visitor's <quote>click path</quote>,
4926 but in most cases she could also get that information by comparing
4927 other parts of the log file: for example the User-Agent if it isn't
4928 a very common one, or the user's IP address if it doesn't change between
4932 Always blocking the referrer, or using a custom one, can lead to
4933 failures on servers that check the referrer before they answer any
4934 requests, in an attempt to prevent their content from being
4935 embedded or linked to elsewhere.
4938 Both <literal>conditional-block</literal> and <literal>forge</literal>
4939 will work with referrer checks, as long as content and valid referring page
4940 are on the same host. Most of the time that's the case.
4943 <literal>hide-referer</literal> is an alternate spelling of
4944 <literal>hide-referrer</literal> and the two can be can be freely
4945 substituted with each other. (<quote>referrer</quote> is the
4946 correct English spelling, however the HTTP specification has a bug - it
4947 requires it to be spelled as <quote>referer</quote>.)
4953 <term>Example usage:</term>
4956 <screen>+hide-referrer{forge}</screen> or
4957 <screen>+hide-referrer{http://www.yahoo.com/}</screen>
4965 <!-- ~~~~~ New section ~~~~~ -->
4966 <sect3 renderas="sect4" id="hide-user-agent">
4967 <title>hide-user-agent</title>
4971 <term>Typical use:</term>
4973 <para>Try to conceal your type of browser and client operating system</para>
4978 <term>Effect:</term>
4981 Replaces the value of the <quote>User-Agent:</quote> HTTP header
4982 in client requests with the specified value.
4989 <!-- Boolean, Parameterized, Multi-value -->
4991 <para>Parameterized.</para>
4996 <term>Parameter:</term>
4999 Any user-defined string.
5009 This can lead to problems on web sites that depend on looking at this header in
5010 order to customize their content for different browsers (which, by the
5011 way, is <emphasis>NOT</emphasis> the right thing to do: good web sites
5012 work browser-independently).
5016 Using this action in multi-user setups or wherever different types of
5017 browsers will access the same <application>Privoxy</application> is
5018 <emphasis>not recommended</emphasis>. In single-user, single-browser
5019 setups, you might use it to delete your OS version information from
5020 the headers, because it is an invitation to exploit known bugs for your
5021 OS. It is also occasionally useful to forge this in order to access
5022 sites that won't let you in otherwise (though there may be a good
5023 reason in some cases).
5026 More information on known user-agent strings can be found at
5027 <ulink url="http://www.user-agents.org/">http://www.user-agents.org/</ulink>
5029 <ulink url="http://en.wikipedia.org/wiki/User_agent">http://en.wikipedia.org/wiki/User_agent</ulink>.
5035 <term>Example usage:</term>
5038 <screen>+hide-user-agent{Netscape 6.1 (X11; I; Linux 2.4.18 i686)}</screen>
5046 <!-- ~~~~~ New section ~~~~~ -->
5047 <sect3 renderas="sect4" id="limit-connect">
5048 <title>limit-connect</title>
5052 <term>Typical use:</term>
5054 <para>Prevent abuse of <application>Privoxy</application> as a TCP proxy relay or disable SSL for untrusted sites</para>
5059 <term>Effect:</term>
5062 Specifies to which ports HTTP CONNECT requests are allowable.
5069 <!-- Boolean, Parameterized, Multi-value -->
5071 <para>Parameterized.</para>
5076 <term>Parameter:</term>
5079 A comma-separated list of ports or port ranges (the latter using dashes, with the minimum
5080 defaulting to 0 and the maximum to 65K).
5089 By default, i.e. if no <literal>limit-connect</literal> action applies,
5090 <application>Privoxy</application> allows HTTP CONNECT requests to all
5091 ports. Use <literal>limit-connect</literal> if fine-grained control
5092 is desired for some or all destinations.
5095 The CONNECT methods exists in HTTP to allow access to secure websites
5096 (<quote>https://</quote> URLs) through proxies. It works very simply:
5097 the proxy connects to the server on the specified port, and then
5098 short-circuits its connections to the client and to the remote server.
5099 This means CONNECT-enabled proxies can be used as TCP relays very easily.
5102 <application>Privoxy</application> relays HTTPS traffic without seeing
5103 the decoded content. Websites can leverage this limitation to circumvent &my-app;'s
5104 filters. By specifying an invalid port range you can disable HTTPS entirely.
5110 <term>Example usages:</term>
5112 <!-- I had trouble getting the spacing to look right in my browser -->
5113 <!-- I probably have the wrong font setup, bollocks. -->
5114 <!-- Apparently the emphasis tag uses a proportional font no matter what -->
5116 <screen>+limit-connect{443} # Port 443 is OK.
5117 +limit-connect{80,443} # Ports 80 and 443 are OK.
5118 +limit-connect{-3, 7, 20-100, 500-} # Ports less than 3, 7, 20 to 100 and above 500 are OK.
5119 +limit-connect{-} # All ports are OK
5120 +limit-connect{,} # No HTTPS/SSL traffic is allowed</screen>
5128 <!-- ~~~~~ New section ~~~~~ -->
5129 <sect3 renderas="sect4" id="limit-cookie-lifetime">
5130 <title>limit-cookie-lifetime</title>
5134 <term>Typical use:</term>
5136 <para>Limit the lifetime of HTTP cookies to a couple of minutes or hours.</para>
5141 <term>Effect:</term>
5144 Overwrites the expires field in Set-Cookie server headers if it's above the specified limit.
5151 <!-- Boolean, Parameterized, Multi-value -->
5153 <para>Parameterized.</para>
5158 <term>Parameter:</term>
5161 The lifetime limit in minutes, or 0.
5170 This action reduces the lifetime of HTTP cookies coming from the
5171 server to the specified number of minutes, starting from the time
5172 the cookie passes Privoxy.
5175 Cookies with a lifetime below the limit are not modified.
5176 The lifetime of session cookies is set to the specified limit.
5179 The effect of this action depends on the server.
5182 In case of servers which refresh their cookies with each response
5183 (or at least frequently), the lifetime limit set by this action
5185 Thus, a session associated with the cookie continues to work with
5186 this action enabled, as long as a new request is made before the
5187 last limit set is reached.
5190 However, some servers send their cookies once, with a lifetime of several
5191 years (the year 2037 is a popular choice), and do not refresh them
5192 until a certain event in the future, for example the user logging out.
5193 In this case this action may limit the absolute lifetime of the session,
5194 even if requests are made frequently.
5197 If the parameter is <quote>0</quote>, this action behaves like
5198 <literal><link linkend="session-cookies-only">session-cookies-only</link></literal>.
5204 <term>Example usages:</term>
5207 <screen>+limit-cookie-lifetime{60}
5215 <!-- ~~~~~ New section ~~~~~ -->
5216 <sect3 renderas="sect4" id="prevent-compression">
5217 <title>prevent-compression</title>
5221 <term>Typical use:</term>
5224 Ensure that servers send the content uncompressed, so it can be
5225 passed through <literal><link linkend="filter">filter</link></literal>s.
5231 <term>Effect:</term>
5234 Removes the Accept-Encoding header which can be used to ask for compressed transfer.
5241 <!-- Boolean, Parameterized, Multi-value -->
5243 <para>Boolean.</para>
5248 <term>Parameter:</term>
5260 More and more websites send their content compressed by default, which
5261 is generally a good idea and saves bandwidth. But the <literal><link
5262 linkend="filter">filter</link></literal> and
5263 <literal><link linkend="deanimate-gifs">deanimate-gifs</link></literal>
5264 actions need access to the uncompressed data.
5267 When compiled with zlib support (available since &my-app; 3.0.7), content that should be
5268 filtered is decompressed on-the-fly and you don't have to worry about this action.
5269 If you are using an older &my-app; version, or one that hasn't been compiled with zlib
5270 support, this action can be used to convince the server to send the content uncompressed.
5273 Most text-based instances compress very well, the size is seldom decreased by less than 50%,
5274 for markup-heavy instances like news feeds saving more than 90% of the original size isn't
5278 Not using compression will therefore slow down the transfer, and you should only
5279 enable this action if you really need it. As of &my-app; 3.0.7 it's disabled in all
5280 predefined action settings.
5283 Note that some (rare) ill-configured sites don't handle requests for uncompressed
5284 documents correctly. Broken PHP applications tend to send an empty document body,
5285 some IIS versions only send the beginning of the content. If you enable
5286 <literal>prevent-compression</literal> per default, you might want to add
5287 exceptions for those sites. See the example for how to do that.
5293 <term>Example usage (sections):</term>
5297 # Selectively turn off compression, and enable a filter
5299 { +filter{tiny-textforms} +prevent-compression }
5300 # Match only these sites
5305 # Or instead, we could set a universal default:
5307 { +prevent-compression }
5310 # Then maybe make exceptions for broken sites:
5312 { -prevent-compression }
5313 .compusa.com/</screen>
5322 <!-- ~~~~~ New section ~~~~~ -->
5323 <sect3 renderas="sect4" id="overwrite-last-modified">
5324 <title>overwrite-last-modified</title>
5330 <term>Typical use:</term>
5332 <para>Prevent yet another way to track the user's steps between sessions.</para>
5337 <term>Effect:</term>
5340 Deletes the <quote>Last-Modified:</quote> HTTP server header or modifies its value.
5347 <!-- Boolean, Parameterized, Multi-value -->
5349 <para>Parameterized.</para>
5354 <term>Parameter:</term>
5357 One of the keywords: <quote>block</quote>, <quote>reset-to-request-time</quote>
5358 and <quote>randomize</quote>
5367 Removing the <quote>Last-Modified:</quote> header is useful for filter
5368 testing, where you want to force a real reload instead of getting status
5369 code <quote>304</quote>, which would cause the browser to reuse the old
5370 version of the page.
5373 The <quote>randomize</quote> option overwrites the value of the
5374 <quote>Last-Modified:</quote> header with a randomly chosen time
5375 between the original value and the current time. In theory the server
5376 could send each document with a different <quote>Last-Modified:</quote>
5377 header to track visits without using cookies. <quote>Randomize</quote>
5378 makes it impossible and the browser can still revalidate cached documents.
5381 <quote>reset-to-request-time</quote> overwrites the value of the
5382 <quote>Last-Modified:</quote> header with the current time. You could use
5383 this option together with
5384 <literal><link linkend="hide-if-modified-since">hide-if-modified-since</link></literal>
5385 to further customize your random range.
5388 The preferred parameter here is <quote>randomize</quote>. It is safe
5389 to use, as long as the time settings are more or less correct.
5390 If the server sets the <quote>Last-Modified:</quote> header to the time
5391 of the request, the random range becomes zero and the value stays the same.
5392 Therefore you should later randomize it a second time with
5393 <literal><link linkend="hide-if-modified-since">hided-if-modified-since</link></literal>,
5397 It is also recommended to use this action together with
5398 <literal><link linkend="crunch-if-none-match">crunch-if-none-match</link></literal>.
5404 <term>Example usage:</term>
5407 <screen># Let the browser revalidate without being tracked across sessions
5408 { +hide-if-modified-since{-60} \
5409 +overwrite-last-modified{randomize} \
5410 +crunch-if-none-match}
5419 <!-- ~~~~~ New section ~~~~~ -->
5420 <sect3 renderas="sect4" id="redirect">
5421 <title>redirect</title>
5427 <term>Typical use:</term>
5430 Redirect requests to other sites.
5436 <term>Effect:</term>
5439 Convinces the browser that the requested document has been moved
5440 to another location and the browser should get it from there.
5447 <!-- Boolean, Parameterized, Multi-value -->
5449 <para>Parameterized</para>
5454 <term>Parameter:</term>
5457 An absolute URL or a single pcrs command.
5466 Requests to which this action applies are answered with a
5467 HTTP redirect to URLs of your choosing. The new URL is
5468 either provided as parameter, or derived by applying a
5469 single pcrs command to the original URL.
5472 The syntax for pcrs commands is documented in the
5473 <link linkend="filter-file">filter file</link> section.
5476 Requests can't be blocked and redirected at the same time,
5477 applying this action together with
5478 <literal><link linkend="block">block</link></literal>
5479 is a configuration error. Currently the request is blocked
5480 and an error message logged, the behavior may change in the
5481 future and result in Privoxy rejecting the action file.
5484 This action can be combined with
5485 <literal><link linkend="fast-redirects">fast-redirects{check-decoded-url}</link></literal>
5486 to redirect to a decoded version of a rewritten URL.
5489 Use this action carefully, make sure not to create redirection loops
5490 and be aware that using your own redirects might make it
5491 possible to fingerprint your requests.
5494 In case of problems with your redirects, or simply to watch
5495 them working, enable <link linkend="DEBUG">debug 128</link>.
5501 <term>Example usages:</term>
5504 <screen># Replace example.com's style sheet with another one
5505 { +redirect{http://localhost/css-replacements/example.com.css} }
5506 example.com/stylesheet\.css
5508 # Create a short, easy to remember nickname for a favorite site
5509 # (relies on the browser to accept and forward invalid URLs to &my-app;)
5510 { +redirect{https://www.privoxy.org/user-manual/actions-file.html} }
5513 # Always use the expanded view for Undeadly.org articles
5514 # (Note the $ at the end of the URL pattern to make sure
5515 # the request for the rewritten URL isn't redirected as well)
5516 {+redirect{s@$@&mode=expanded@}}
5517 undeadly.org/cgi\?action=article&sid=\d*$
5519 # Redirect Google search requests to MSN
5520 {+redirect{s@^http://[^/]*/search\?q=([^&]*).*@http://search.msn.com/results.aspx?q=$1@}}
5523 # Redirect MSN search requests to Yahoo
5524 {+redirect{s@^http://[^/]*/results\.aspx\?q=([^&]*).*@http://search.yahoo.com/search?p=$1@}}
5525 search.msn.com//results\.aspx\?q=
5527 # Redirect http://example.com/&bla=fasel&toChange=foo (and any other value but "bar")
5528 # to http://example.com/&bla=fasel&toChange=bar
5530 # The URL pattern makes sure that the following request isn't redirected again.
5531 {+redirect{s@toChange=[^&]+@toChange=bar@}}
5532 example.com/.*toChange=(?!bar)
5534 # Add a shortcut to look up illumos bugs
5535 {+redirect{s@^http://i([0-9]+)/.*@https://www.illumos.org/issues/$1@}}
5536 # Redirected URL = http://i4974/
5537 # Redirect Destination = https://www.illumos.org/issues/4974
5538 i[0-9][0-9][0-9][0-9]*/
5540 # Redirect remote requests for this manual
5541 # to the local version delivered by Privoxy
5542 {+redirect{s@^http://www@http://config@}}
5543 www.privoxy.org/user-manual/</screen>
5552 <!-- ~~~~~ New section ~~~~~ -->
5553 <sect3 renderas="sect4" id="server-header-filter">
5554 <title>server-header-filter</title>
5558 <term>Typical use:</term>
5561 Rewrite or remove single server headers.
5567 <term>Effect:</term>
5570 All server headers to which this action applies are filtered on-the-fly
5571 through the specified regular expression based substitutions.
5578 <!-- boolean, parameterized, Multi-value -->
5580 <para>Multi-value.</para>
5585 <term>Parameter:</term>
5588 The name of a server-header filter, as defined in one of the
5589 <link linkend="filter-file">filter files</link>.
5598 Server-header filters are applied to each header on its own, not to
5599 all at once. This makes it easier to diagnose problems, but on the downside
5600 you can't write filters that only change header x if header y's value is z.
5601 You can do that by using tags though.
5604 Server-header filters are executed after the other header actions have finished
5605 and use their output as input.
5608 Please refer to the <link linkend="filter-file">filter file chapter</link>
5609 to learn which server-header filters are available by default, and how to
5616 <term>Example usage (section):</term>
5620 {+server-header-filter{html-to-xml}}
5621 example.org/xml-instance-that-is-delivered-as-html
5623 {+server-header-filter{xml-to-html}}
5624 example.org/instance-that-is-delivered-as-xml-but-is-not
5634 <!-- ~~~~~ New section ~~~~~ -->
5635 <sect3 renderas="sect4" id="server-header-tagger">
5636 <title>server-header-tagger</title>
5640 <term>Typical use:</term>
5643 Enable or disable filters based on the Content-Type header.
5649 <term>Effect:</term>
5652 Server headers to which this action applies are filtered on-the-fly through
5653 the specified regular expression based substitutions, the result is used as
5661 <!-- boolean, parameterized, Multi-value -->
5663 <para>Multi-value.</para>
5668 <term>Parameter:</term>
5671 The name of a server-header tagger, as defined in one of the
5672 <link linkend="filter-file">filter files</link>.
5681 Server-header taggers are applied to each header on its own,
5682 and as the header isn't modified, each tagger <quote>sees</quote>
5686 Server-header taggers are executed before all other header actions
5687 that modify server headers. Their tags can be used to control
5688 all of the other server-header actions, the content filters
5689 and the crunch actions (<link linkend="redirect">redirect</link>
5690 and <link linkend="block">block</link>).
5693 Obviously crunching based on tags created by server-header taggers
5694 doesn't prevent the request from showing up in the server's log file.
5701 <term>Example usage (section):</term>
5705 # Tag every request with the content type declared by the server
5706 {+server-header-tagger{content-type}}
5709 # If the response has a tag starting with 'image/' enable an external
5710 # filter that only applies to images.
5712 # Note that the filter is not available by default, it's just a
5713 # <literal><link linkend="external-filter-syntax">silly example</link></literal>.
5714 {+external-filter{rotate-image} +force-text-mode}
5725 <!-- ~~~~~ New section ~~~~~ -->
5726 <sect3 renderas="sect4" id="session-cookies-only">
5727 <title>session-cookies-only</title>
5731 <term>Typical use:</term>
5734 Allow only temporary <quote>session</quote> cookies (for the current
5735 browser session <emphasis>only</emphasis>).
5741 <term>Effect:</term>
5744 Deletes the <quote>expires</quote> field from <quote>Set-Cookie:</quote>
5745 server headers. Most browsers will not store such cookies permanently and
5746 forget them in between sessions.
5753 <!-- Boolean, Parameterized, Multi-value -->
5755 <para>Boolean.</para>
5760 <term>Parameter:</term>
5772 This is less strict than <literal><link linkend="crunch-incoming-cookies">crunch-incoming-cookies</link></literal> /
5773 <literal><link linkend="crunch-outgoing-cookies">crunch-outgoing-cookies</link></literal> and allows you to browse
5774 websites that insist or rely on setting cookies, without compromising your privacy too badly.
5777 Most browsers will not permanently store cookies that have been processed by
5778 <literal>session-cookies-only</literal> and will forget about them between sessions.
5779 This makes profiling cookies useless, but won't break sites which require cookies so
5780 that you can log in for transactions. This is generally turned on for all
5781 sites, and is the recommended setting.
5784 It makes <emphasis>no sense at all</emphasis> to use <literal>session-cookies-only</literal>
5785 together with <literal><link linkend="crunch-incoming-cookies">crunch-incoming-cookies</link></literal> or
5786 <literal><link linkend="crunch-outgoing-cookies">crunch-outgoing-cookies</link></literal>. If you do, cookies
5787 will be plainly killed.
5790 Note that it is up to the browser how it handles such cookies without an <quote>expires</quote>
5791 field. If you use an exotic browser, you might want to try it out to be sure.
5794 This setting also has no effect on cookies that may have been stored
5795 previously by the browser before starting <application>Privoxy</application>.
5796 These would have to be removed manually.
5799 <application>Privoxy</application> also uses
5800 the <link linkend="filter-content-cookies">content-cookies filter</link>
5801 to block some types of cookies. Content cookies are not effected by
5802 <literal>session-cookies-only</literal>.
5808 <term>Example usage:</term>
5811 <screen>+session-cookies-only</screen>
5819 <!-- ~~~~~ New section ~~~~~ -->
5820 <sect3 renderas="sect4" id="set-image-blocker">
5821 <title>set-image-blocker</title>
5825 <term>Typical use:</term>
5827 <para>Choose the replacement for blocked images</para>
5832 <term>Effect:</term>
5835 This action alone doesn't do anything noticeable. If <emphasis>both</emphasis>
5836 <literal><link linkend="block">block</link></literal> <emphasis>and</emphasis> <literal><link
5837 linkend="handle-as-image">handle-as-image</link></literal> <emphasis>also</emphasis>
5838 apply, i.e. if the request is to be blocked as an image,
5839 <emphasis>then</emphasis> the parameter of this action decides what will be
5840 sent as a replacement.
5847 <!-- Boolean, Parameterized, Multi-value -->
5849 <para>Parameterized.</para>
5854 <term>Parameter:</term>
5859 <quote>pattern</quote> to send a built-in checkerboard pattern image. The image is visually
5860 decent, scales very well, and makes it obvious where banners were busted.
5865 <quote>blank</quote> to send a built-in transparent image. This makes banners disappear
5866 completely, but makes it hard to detect where <application>Privoxy</application> has blocked
5867 images on a given page and complicates troubleshooting if <application>Privoxy</application>
5868 has blocked innocent images, like navigation icons.
5873 <quote><replaceable class="parameter">target-url</replaceable></quote> to
5874 send a redirect to <replaceable class="parameter">target-url</replaceable>. You can redirect
5875 to any image anywhere, even in your local filesystem via <quote>file:///</quote> URL.
5876 (But note that not all browsers support redirecting to a local file system).
5879 A good application of redirects is to use special <application>Privoxy</application>-built-in
5880 URLs, which send the built-in images, as <replaceable class="parameter">target-url</replaceable>.
5881 This has the same visual effect as specifying <quote>blank</quote> or <quote>pattern</quote> in
5882 the first place, but enables your browser to cache the replacement image, instead of requesting
5883 it over and over again.
5894 The URLs for the built-in images are <quote>http://config.privoxy.org/send-banner?type=<replaceable
5895 class="parameter">type</replaceable></quote>, where <replaceable class="parameter">type</replaceable> is
5896 either <quote>blank</quote> or <quote>pattern</quote>.
5899 There is a third (advanced) type, called <quote>auto</quote>. It is <emphasis>NOT</emphasis> to be
5900 used in <literal>set-image-blocker</literal>, but meant for use from <link linkend="filter-file">filters</link>.
5901 Auto will select the type of image that would have applied to the referring page, had it been an image.
5907 <term>Example usage:</term>
5913 <screen>+set-image-blocker{pattern}</screen>
5916 Redirect to the BSD daemon:
5919 <screen>+set-image-blocker{http://www.freebsd.org/gifs/dae_up3.gif}</screen>
5922 Redirect to the built-in pattern for better caching:
5925 <screen>+set-image-blocker{http://config.privoxy.org/send-banner?type=pattern}</screen>
5933 <!-- ~~~~~ New section ~~~~~ -->
5934 <sect3 id="summary">
5935 <title>Summary</title>
5937 Note that many of these actions have the potential to cause a page to
5938 misbehave, possibly even not to display at all. There are many ways
5939 a site designer may choose to design his site, and what HTTP header
5940 content, and other criteria, he may depend on. There is no way to have hard
5941 and fast rules for all sites. See the <link
5942 linkend="ACTIONSANAT">Appendix</link> for a brief example on troubleshooting
5948 <!-- ~~~~~ New section ~~~~~ -->
5949 <sect2 id="aliases">
5950 <title>Aliases</title>
5952 Custom <quote>actions</quote>, known to <application>Privoxy</application>
5953 as <quote>aliases</quote>, can be defined by combining other actions.
5954 These can in turn be invoked just like the built-in actions.
5955 Currently, an alias name can contain any character except space, tab,
5957 <quote>{</quote> and <quote>}</quote>, but we <emphasis>strongly
5958 recommend</emphasis> that you only use <quote>a</quote> to <quote>z</quote>,
5959 <quote>0</quote> to <quote>9</quote>, <quote>+</quote>, and <quote>-</quote>.
5960 Alias names are not case sensitive, and are not required to start with a
5961 <quote>+</quote> or <quote>-</quote> sign, since they are merely textually
5965 Aliases can be used throughout the actions file, but they <emphasis>must be
5966 defined in a special section at the top of the file!</emphasis>
5967 And there can only be one such section per actions file. Each actions file may
5968 have its own alias section, and the aliases defined in it are only visible
5972 There are two main reasons to use aliases: One is to save typing for frequently
5973 used combinations of actions, the other one is a gain in flexibility: If you
5974 decide once how you want to handle shops by defining an alias called
5975 <quote>shop</quote>, you can later change your policy on shops in
5976 <emphasis>one</emphasis> place, and your changes will take effect everywhere
5977 in the actions file where the <quote>shop</quote> alias is used. Calling aliases
5978 by their purpose also makes your actions files more readable.
5981 Currently, there is one big drawback to using aliases, though:
5982 <application>Privoxy</application>'s built-in web-based action file
5983 editor honors aliases when reading the actions files, but it expands
5984 them before writing. So the effects of your aliases are of course preserved,
5985 but the aliases themselves are lost when you edit sections that use aliases
5990 Now let's define some aliases...
5995 # Useful custom aliases we can use later.
5997 # Note the (required!) section header line and that this section
5998 # must be at the top of the actions file!
6002 # These aliases just save typing later:
6003 # (Note that some already use other aliases!)
6005 +crunch-all-cookies = +<link linkend="CRUNCH-INCOMING-COOKIES">crunch-incoming-cookies</link> +<link linkend="CRUNCH-OUTGOING-COOKIES">crunch-outgoing-cookies</link>
6006 -crunch-all-cookies = -<link linkend="CRUNCH-INCOMING-COOKIES">crunch-incoming-cookies</link> -<link linkend="CRUNCH-OUTGOING-COOKIES">crunch-outgoing-cookies</link>
6007 +block-as-image = +block{Blocked image.} +handle-as-image
6008 allow-all-cookies = -crunch-all-cookies -<link linkend="SESSION-COOKIES-ONLY">session-cookies-only</link> -<link linkend="FILTER-CONTENT-COOKIES">filter{content-cookies}</link>
6010 # These aliases define combinations of actions
6011 # that are useful for certain types of sites:
6013 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>
6015 shop = -crunch-all-cookies -<link linkend="FILTER-ALL-POPUPS">filter{all-popups}</link>
6017 # Short names for other aliases, for really lazy people ;-)
6019 c0 = +crunch-all-cookies
6020 c1 = -crunch-all-cookies</screen>
6024 ...and put them to use. These sections would appear in the lower part of an
6025 actions file and define exceptions to the default actions (as specified further
6026 up for the <quote>/</quote> pattern):
6031 # These sites are either very complex or very keen on
6032 # user data and require minimal interference to work:
6035 .office.microsoft.com
6036 .windowsupdate.microsoft.com
6037 # Gmail is really mail.google.com, not gmail.com
6041 # Allow cookies (for setting and retrieving your customer data)
6045 .worldpay.com # for quietpc.com
6048 # These shops require pop-ups:
6050 {-filter{all-popups} -filter{unsolicited-popups}}
6052 .overclockers.co.uk</screen>
6056 Aliases like <quote>shop</quote> and <quote>fragile</quote> are typically used for
6057 <quote>problem</quote> sites that require more than one action to be disabled
6058 in order to function properly.
6064 <!-- ~~~~~ New section ~~~~~ -->
6065 <sect2 id="act-examples">
6066 <title>Actions Files Tutorial</title>
6068 The above chapters have shown <link linkend="actions-file">which actions files
6069 there are and how they are organized</link>, how actions are <link
6070 linkend="actions">specified</link> and <link linkend="actions-apply">applied
6071 to URLs</link>, how <link linkend="af-patterns">patterns</link> work, and how to
6072 define and use <link linkend="aliases">aliases</link>. Now, let's look at an
6073 example <filename>match-all.action</filename>, <filename>default.action</filename>
6074 and <filename>user.action</filename> file and see how all these pieces come together:
6077 <sect3 id="match-all">
6078 <title>match-all.action</title>
6080 Remember <emphasis>all actions are disabled when matching starts</emphasis>,
6081 so we have to explicitly enable the ones we want.
6085 While the <filename>match-all.action</filename> file only contains a
6086 single section, it is probably the most important one. It has only one
6087 pattern, <quote><literal>/</literal></quote>, but this pattern
6088 <link linkend="af-patterns">matches all URLs</link>. Therefore, the set of
6089 actions used in this <quote>default</quote> section <emphasis>will
6090 be applied to all requests as a start</emphasis>. It can be partly or
6091 wholly overridden by other actions files like <filename>default.action</filename>
6092 and <filename>user.action</filename>, but it will still be largely responsible
6093 for your overall browsing experience.
6097 Again, at the start of matching, all actions are disabled, so there is
6098 no need to disable any actions here. (Remember: a <quote>+</quote>
6099 preceding the action name enables the action, a <quote>-</quote> disables!).
6100 Also note how this long line has been made more readable by splitting it into
6101 multiple lines with line continuation.
6107 +<link linkend="CHANGE-X-FORWARDED-FOR">change-x-forwarded-for{block}</link> \
6108 +<link linkend="HIDE-FROM-HEADER">hide-from-header{block}</link> \
6109 +<link linkend="SET-IMAGE-BLOCKER">set-image-blocker{pattern}</link> \
6116 The default behavior is now set.
6120 <sect3 id="default-action">
6121 <title>default.action</title>
6124 If you aren't a developer, there's no need for you to edit the
6125 <filename>default.action</filename> file. It is maintained by
6126 the &my-app; developers and if you disagree with some of the
6127 sections, you should overrule them in your <filename>user.action</filename>.
6131 Understanding the <filename>default.action</filename> file can
6132 help you with your <filename>user.action</filename>, though.
6136 The first section in this file is a special section for internal use
6137 that prevents older &my-app; versions from reading the file:
6142 ##########################################################################
6143 # Settings -- Don't change! For internal Privoxy use ONLY.
6144 ##########################################################################
6146 for-privoxy-version=3.0.11</screen>
6150 After that comes the (optional) alias section. We'll use the example
6151 section from the above <link linkend="aliases">chapter on aliases</link>,
6152 that also explains why and how aliases are used:
6157 ##########################################################################
6159 ##########################################################################
6162 # These aliases just save typing later:
6163 # (Note that some already use other aliases!)
6165 +crunch-all-cookies = +<link linkend="CRUNCH-INCOMING-COOKIES">crunch-incoming-cookies</link> +<link linkend="CRUNCH-OUTGOING-COOKIES">crunch-outgoing-cookies</link>
6166 -crunch-all-cookies = -<link linkend="CRUNCH-INCOMING-COOKIES">crunch-incoming-cookies</link> -<link linkend="CRUNCH-OUTGOING-COOKIES">crunch-outgoing-cookies</link>
6167 +block-as-image = +block{Blocked image.} +handle-as-image
6168 mercy-for-cookies = -crunch-all-cookies -<link linkend="SESSION-COOKIES-ONLY">session-cookies-only</link> -<link linkend="FILTER-CONTENT-COOKIES">filter{content-cookies}</link>
6170 # These aliases define combinations of actions
6171 # that are useful for certain types of sites:
6173 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>
6174 shop = -crunch-all-cookies -<link linkend="FILTER-ALL-POPUPS">filter{all-popups}</link></screen>
6178 The first of our specialized sections is concerned with <quote>fragile</quote>
6179 sites, i.e. sites that require minimum interference, because they are either
6180 very complex or very keen on tracking you (and have mechanisms in place that
6181 make them unusable for people who avoid being tracked). We will use
6182 our pre-defined <literal>fragile</literal> alias instead of stating the list
6183 of actions explicitly:
6188 ##########################################################################
6189 # Exceptions for sites that'll break under the default action set:
6190 ##########################################################################
6192 # "Fragile" Use a minimum set of actions for these sites (see alias above):
6195 .office.microsoft.com # surprise, surprise!
6196 .windowsupdate.microsoft.com
6197 mail.google.com</screen>
6201 Shopping sites are not as fragile, but they typically
6202 require cookies to log in, and pop-up windows for shopping
6203 carts or item details. Again, we'll use a pre-defined alias:
6212 .worldpay.com # for quietpc.com
6214 .scan.co.uk</screen>
6218 The <literal><link linkend="FAST-REDIRECTS">fast-redirects</link></literal>
6219 action, which may have been enabled in <filename>match-all.action</filename>,
6220 breaks some sites. So disable it for popular sites where we know it misbehaves:
6225 { -<link linkend="FAST-REDIRECTS">fast-redirects</link> }
6229 .altavista.com/.*(like|url|link):http
6230 .altavista.com/trans.*urltext=http
6231 .nytimes.com</screen>
6235 It is important that <application>Privoxy</application> knows which
6236 URLs belong to images, so that <emphasis>if</emphasis> they are to
6237 be blocked, a substitute image can be sent, rather than an HTML page.
6238 Contacting the remote site to find out is not an option, since it
6239 would destroy the loading time advantage of banner blocking, and it
6240 would feed the advertisers information about you. We can mark any
6241 URL as an image with the <literal><link
6242 linkend="handle-as-image">handle-as-image</link></literal> action,
6243 and marking all URLs that end in a known image file extension is a
6249 ##########################################################################
6251 ##########################################################################
6253 # Define which file types will be treated as images, in case they get
6254 # blocked further down this file:
6256 { +<link linkend="HANDLE-AS-IMAGE">handle-as-image</link> }
6257 /.*\.(gif|jpe?g|png|bmp|ico)$</screen>
6261 And then there are known banner sources. They often use scripts to
6262 generate the banners, so it won't be visible from the URL that the
6263 request is for an image. Hence we block them <emphasis>and</emphasis>
6264 mark them as images in one go, with the help of our
6265 <literal>+block-as-image</literal> alias defined above. (We could of
6266 course just as well use <literal>+<link linkend="block">block</link>
6267 +<link linkend="handle-as-image">handle-as-image</link></literal> here.)
6268 Remember that the type of the replacement image is chosen by the
6269 <literal><link linkend="set-image-blocker">set-image-blocker</link></literal>
6270 action. Since all URLs have matched the default section with its
6271 <literal>+<link linkend="set-image-blocker">set-image-blocker</link>{pattern}</literal>
6272 action before, it still applies and needn't be repeated:
6277 # Known ad generators:
6282 .ad.*.doubleclick.net
6283 .a.yimg.com/(?:(?!/i/).)*$
6284 .a[0-9].yimg.com/(?:(?!/i/).)*$
6290 One of the most important jobs of <application>Privoxy</application>
6291 is to block banners. Many of these can be <quote>blocked</quote>
6292 by the <literal><link linkend="filter">filter</link>{banners-by-size}</literal>
6293 action, which we enabled above, and which deletes the references to banner
6294 images from the pages while they are loaded, so the browser doesn't request
6295 them anymore, and hence they don't need to be blocked here. But this naturally
6296 doesn't catch all banners, and some people choose not to use filters, so we
6297 need a comprehensive list of patterns for banner URLs here, and apply the
6298 <literal><link linkend="block">block</link></literal> action to them.
6301 First comes many generic patterns, which do most of the work, by
6302 matching typical domain and path name components of banners. Then comes
6303 a list of individual patterns for specific sites, which is omitted here
6304 to keep the example short:
6309 ##########################################################################
6310 # Block these fine banners:
6311 ##########################################################################
6312 { <link linkend="BLOCK">+block{Banner ads.}</link> }
6320 /.*count(er)?\.(pl|cgi|exe|dll|asp|php[34]?)
6321 /(?:.*/)?(publicite|werbung|rekla(ma|me|am)|annonse|maino(kset|nta|s)?)/
6323 # Site-specific patterns (abbreviated):
6325 .hitbox.com</screen>
6329 It's quite remarkable how many advertisers actually call their banner
6330 servers ads.<replaceable>company</replaceable>.com, or call the directory
6331 in which the banners are stored literally <quote>banners</quote>. So the above
6332 generic patterns are surprisingly effective.
6335 But being very generic, they necessarily also catch URLs that we don't want
6336 to block. The pattern <literal>.*ads.</literal> e.g. catches
6337 <quote>nasty-<emphasis>ads</emphasis>.nasty-corp.com</quote> as intended,
6338 but also <quote>downlo<emphasis>ads</emphasis>.sourcefroge.net</quote> or
6339 <quote><emphasis>ads</emphasis>l.some-provider.net.</quote> So here come some
6340 well-known exceptions to the <literal>+<link linkend="BLOCK">block</link></literal>
6344 Note that these are exceptions to exceptions from the default! Consider the URL
6345 <quote>downloads.sourcefroge.net</quote>: Initially, all actions are deactivated,
6346 so it wouldn't get blocked. Then comes the defaults section, which matches the
6347 URL, but just deactivates the <literal><link linkend="BLOCK">block</link></literal>
6348 action once again. Then it matches <literal>.*ads.</literal>, an exception to the
6349 general non-blocking policy, and suddenly
6350 <literal><link linkend="BLOCK">+block</link></literal> applies. And now, it'll match
6351 <literal>.*loads.</literal>, where <literal><link linkend="BLOCK">-block</link></literal>
6352 applies, so (unless it matches <emphasis>again</emphasis> further down) it ends up
6353 with no <literal><link linkend="BLOCK">block</link></literal> action applying.
6358 ##########################################################################
6359 # Save some innocent victims of the above generic block patterns:
6360 ##########################################################################
6364 { -<link linkend="BLOCK">block</link> }
6365 adv[io]*. # (for advogato.org and advice.*)
6366 adsl. # (has nothing to do with ads)
6367 adobe. # (has nothing to do with ads either)
6368 ad[ud]*. # (adult.* and add.*)
6369 .edu # (universities don't host banners (yet!))
6370 .*loads. # (downloads, uploads etc)
6378 www.globalintersec.com/adv # (adv = advanced)
6379 www.ugu.com/sui/ugu/adv</screen>
6383 Filtering source code can have nasty side effects,
6384 so make an exception for our friends at sourceforge.net,
6385 and all paths with <quote>cvs</quote> in them. Note that
6386 <literal>-<link linkend="FILTER">filter</link></literal>
6387 disables <emphasis>all</emphasis> filters in one fell swoop!
6392 # Don't filter code!
6394 { -<link linkend="FILTER">filter</link> }
6399 .sourceforge.net</screen>
6403 The actual <filename>default.action</filename> is of course much more
6404 comprehensive, but we hope this example made clear how it works.
6409 <sect3 id="user-action"><title>user.action</title>
6412 So far we are painting with a broad brush by setting general policies,
6413 which would be a reasonable starting point for many people. Now,
6414 you might want to be more specific and have customized rules that
6415 are more suitable to your personal habits and preferences. These would
6416 be for narrowly defined situations like your ISP or your bank, and should
6417 be placed in <filename>user.action</filename>, which is parsed after all other
6418 actions files and hence has the last word, over-riding any previously
6419 defined actions. <filename>user.action</filename> is also a
6420 <emphasis>safe</emphasis> place for your personal settings, since
6421 <filename>default.action</filename> is actively maintained by the
6422 <application>Privoxy</application> developers and you'll probably want
6423 to install updated versions from time to time.
6427 So let's look at a few examples of things that one might typically do in
6428 <filename>user.action</filename>:
6432 <!-- brief sample user.action here -->
6436 # My user.action file. <fred@example.com></screen>
6440 As <link linkend="aliases">aliases</link> are local to the actions
6441 file that they are defined in, you can't use the ones from
6442 <filename>default.action</filename>, unless you repeat them here:
6447 # Aliases are local to the file they are defined in.
6448 # (Re-)define aliases for this file:
6452 # These aliases just save typing later, and the alias names should
6453 # be self explanatory.
6455 +crunch-all-cookies = +crunch-incoming-cookies +crunch-outgoing-cookies
6456 -crunch-all-cookies = -crunch-incoming-cookies -crunch-outgoing-cookies
6457 allow-all-cookies = -crunch-all-cookies -session-cookies-only
6458 allow-popups = -filter{all-popups}
6459 +block-as-image = +block{Blocked as image.} +handle-as-image
6460 -block-as-image = -block
6462 # These aliases define combinations of actions that are useful for
6463 # certain types of sites:
6465 fragile = -block -crunch-all-cookies -filter -fast-redirects -hide-referrer
6466 shop = -crunch-all-cookies allow-popups
6468 # Allow ads for selected useful free sites:
6470 allow-ads = -block -filter{banners-by-size} -filter{banners-by-link}
6472 # Alias for specific file types that are text, but might have conflicting
6473 # MIME types. We want the browser to force these to be text documents.
6474 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>
6478 Say you have accounts on some sites that you visit regularly, and
6479 you don't want to have to log in manually each time. So you'd like
6480 to allow persistent cookies for these sites. The
6481 <literal>allow-all-cookies</literal> alias defined above does exactly
6482 that, i.e. it disables crunching of cookies in any direction, and the
6483 processing of cookies to make them only temporary.
6488 { allow-all-cookies }
6492 .redhat.com</screen>
6496 Your bank is allergic to some filter, but you don't know which, so you disable them all:
6501 { -<link linkend="FILTER">filter</link> }
6502 .your-home-banking-site.com</screen>
6506 Some file types you may not want to filter for various reasons:
6511 # Technical documentation is likely to contain strings that might
6512 # erroneously get altered by the JavaScript-oriented filters:
6517 # And this stupid host sends streaming video with a wrong MIME type,
6518 # so that Privoxy thinks it is getting HTML and starts filtering:
6520 stupid-server.example.com/</screen>
6524 Example of a simple <link linkend="BLOCK">block</link> action. Say you've
6525 seen an ad on your favourite page on example.com that you want to get rid of.
6526 You have right-clicked the image, selected <quote>copy image location</quote>
6527 and pasted the URL below while removing the leading http://, into a
6528 <literal>{ +block{} }</literal> section. Note that <literal>{ +handle-as-image
6529 }</literal> need not be specified, since all URLs ending in
6530 <literal>.gif</literal> will be tagged as images by the general rules as set
6531 in default.action anyway:
6536 { +<link linkend="BLOCK">block</link>{Nasty ads.} }
6537 www.example.com/nasty-ads/sponsor\.gif
6538 another.example.net/more/junk/here/</screen>
6542 The URLs of dynamically generated banners, especially from large banner
6543 farms, often don't use the well-known image file name extensions, which
6544 makes it impossible for <application>Privoxy</application> to guess
6545 the file type just by looking at the URL.
6546 You can use the <literal>+block-as-image</literal> alias defined above for
6548 Note that objects which match this rule but then turn out NOT to be an
6549 image are typically rendered as a <quote>broken image</quote> icon by the
6550 browser. Use cautiously.
6559 ar.atwola.com/</screen>
6563 Now you noticed that the default configuration breaks Forbes Magazine,
6564 but you were too lazy to find out which action is the culprit, and you
6565 were again too lazy to give <link linkend="contact">feedback</link>, so
6566 you just used the <literal>fragile</literal> alias on the site, and
6567 -- <emphasis>whoa!</emphasis> -- it worked. The <literal>fragile</literal>
6568 aliases disables those actions that are most likely to break a site. Also,
6569 good for testing purposes to see if it is <application>Privoxy</application>
6570 that is causing the problem or not. We later find other regular sites
6571 that misbehave, and add those to our personalized list of troublemakers:
6579 .mybank.com</screen>
6583 You like the <quote>fun</quote> text replacements in <filename>default.filter</filename>,
6584 but it is disabled in the distributed actions file.
6585 So you'd like to turn it on in your private,
6586 update-safe config, once and for all:
6591 { +<link linkend="filter-fun">filter{fun}</link> }
6592 / # For ALL sites!</screen>
6596 Note that the above is not really a good idea: There are exceptions
6597 to the filters in <filename>default.action</filename> for things that
6598 really shouldn't be filtered, like code on CVS->Web interfaces. Since
6599 <filename>user.action</filename> has the last word, these exceptions
6600 won't be valid for the <quote>fun</quote> filtering specified here.
6604 You might also worry about how your favourite free websites are
6605 funded, and find that they rely on displaying banner advertisements
6606 to survive. So you might want to specifically allow banners for those
6607 sites that you feel provide value to you:
6619 Note that <literal>allow-ads</literal> has been aliased to
6620 <literal>-<link linkend="block">block</link></literal>,
6621 <literal>-<link linkend="filter-banners-by-size">filter{banners-by-size}</link></literal>, and
6622 <literal>-<link linkend="filter-banners-by-link">filter{banners-by-link}</link></literal> above.
6626 Invoke another alias here to force an over-ride of the MIME type <literal>
6627 application/x-sh</literal> which typically would open a download type
6628 dialog. In my case, I want to look at the shell script, and then I can save
6629 it should I choose to.
6639 <filename>user.action</filename> is generally the best place to define
6640 exceptions and additions to the default policies of
6641 <filename>default.action</filename>. Some actions are safe to have their
6642 default policies set here though. So let's set a default policy to have a
6643 <quote>blank</quote> image as opposed to the checkerboard pattern for
6644 <emphasis>ALL</emphasis> sites. <quote>/</quote> of course matches all URL
6650 { +<link linkend="set-image-blocker">set-image-blocker{blank}</link> }
6651 / # ALL sites</screen>
6657 <!-- ~ End section ~ -->
6661 <!-- ~ End section ~ -->
6663 <!-- ~~~~~~~~ New section Header ~~~~~~~~~ -->
6665 <sect1 id="filter-file">
6666 <title>Filter Files</title>
6669 On-the-fly text substitutions need
6670 to be defined in a <quote>filter file</quote>. Once defined, they
6671 can then be invoked as an <quote>action</quote>.
6675 &my-app; supports three different pcrs-based filter actions:
6676 <literal><link linkend="filter">filter</link></literal> to
6677 rewrite the content that is send to the client,
6678 <literal><link linkend="client-header-filter">client-header-filter</link></literal>
6679 to rewrite headers that are send by the client, and
6680 <literal><link linkend="server-header-filter">server-header-filter</link></literal>
6681 to rewrite headers that are send by the server.
6685 &my-app; also supports two tagger actions:
6686 <literal><link linkend="client-header-tagger">client-header-tagger</link></literal>
6688 <literal><link linkend="server-header-tagger">server-header-tagger</link></literal>.
6689 Taggers and filters use the same syntax in the filter files, the difference
6690 is that taggers don't modify the text they are filtering, but use a rewritten
6691 version of the filtered text as tag. The tags can then be used to change the
6692 applying actions through sections with <link linkend="tag-pattern">tag-patterns</link>.
6696 Finally &my-app; supports the
6697 <literal><link linkend="external-filter">external-filter</link></literal> action
6698 to enable <literal><link linkend="external-filter-syntax">external filters</link></literal>
6699 written in proper programming languages.
6704 Multiple filter files can be defined through the <literal> <link
6705 linkend="filterfile">filterfile</link></literal> config directive. The filters
6706 as supplied by the developers are located in
6707 <filename>default.filter</filename>. It is recommended that any locally
6708 defined or modified filters go in a separately defined file such as
6709 <filename>user.filter</filename>.
6713 Common tasks for content filters are to eliminate common annoyances in
6714 HTML and JavaScript, such as pop-up windows,
6715 exit consoles, crippled windows without navigation tools, the
6716 infamous <BLINK> tag etc, to suppress images with certain
6717 width and height attributes (standard banner sizes or web-bugs),
6718 or just to have fun.
6722 Enabled content filters are applied to any content whose
6723 <quote>Content Type</quote> header is recognised as a sign
6724 of text-based content, with the exception of <literal>text/plain</literal>.
6725 Use the <link linkend="FORCE-TEXT-MODE">force-text-mode</link> action
6726 to also filter other content.
6730 Substitutions are made at the source level, so if you want to <quote>roll
6731 your own</quote> filters, you should first be familiar with HTML syntax,
6732 and, of course, regular expressions.
6736 Just like the <link linkend="actions-file">actions files</link>, the
6737 filter file is organized in sections, which are called <emphasis>filters</emphasis>
6738 here. Each filter consists of a heading line, that starts with one of the
6739 <emphasis>keywords</emphasis> <literal>FILTER:</literal>,
6740 <literal>CLIENT-HEADER-FILTER:</literal> or <literal>SERVER-HEADER-FILTER:</literal>
6741 followed by the filter's <emphasis>name</emphasis>, and a short (one line)
6742 <emphasis>description</emphasis> of what it does. Below that line
6743 come the <emphasis>jobs</emphasis>, i.e. lines that define the actual
6744 text substitutions. By convention, the name of a filter
6745 should describe what the filter <emphasis>eliminates</emphasis>. The
6746 comment is used in the <ulink url="http://config.privoxy.org/">web-based
6747 user interface</ulink>.
6751 Once a filter called <replaceable>name</replaceable> has been defined
6752 in the filter file, it can be invoked by using an action of the form
6753 +<literal><link linkend="filter">filter</link>{<replaceable>name</replaceable>}</literal>
6754 in any <link linkend="actions-file">actions file</link>.
6758 Filter definitions start with a header line that contains the filter
6759 type, the filter name and the filter description.
6760 A content filter header line for a filter called <quote>foo</quote> could look
6765 <screen>FILTER: foo Replace all "foo" with "bar"</screen>
6769 Below that line, and up to the next header line, come the jobs that
6770 define what text replacements the filter executes. They are specified
6771 in a syntax that imitates <ulink url="http://www.perl.org/">Perl</ulink>'s
6772 <literal>s///</literal> operator. If you are familiar with Perl, you
6773 will find this to be quite intuitive, and may want to look at the
6774 PCRS documentation for the subtle differences to Perl behaviour.
6778 Most notably, the non-standard option letter <literal>U</literal> is supported,
6779 which turns the default to ungreedy matching (add <literal>?</literal> to
6780 quantifiers to turn them greedy again).
6784 The non-standard option letter <literal>D</literal> (dynamic) allows
6785 to use the variables $host, $origin (the IP address the request came from),
6786 $path, $url and $listen-address (the address on which Privoxy accepted the
6787 client request. Example: 127.0.0.1:8118).
6788 They will be replaced with the value they refer to before the filter
6793 Note that '$' is a bad choice for a delimiter in a dynamic filter as you
6794 might end up with unintended variables if you use a variable name
6795 directly after the delimiter. Variables will be resolved without
6796 escaping anything, therefore you also have to be careful not to chose
6797 delimiters that appear in the replacement text. For example '<' should
6798 be save, while '?' will sooner or later cause conflicts with $url.
6802 The non-standard option letter <literal>T</literal> (trivial) prevents
6803 parsing for backreferences in the substitute. Use it if you want to include
6804 text like '$&' in your substitute without quoting.
6809 <ulink url="http://en.wikipedia.org/wiki/Regular_expressions"><quote>Regular
6810 Expressions</quote></ulink>, you might want to take a look at
6811 the <link linkend="regex">Appendix on regular expressions</link>, and
6812 see the <ulink url="http://perldoc.perl.org/perlre.html">Perl
6814 <ulink url="http://perldoc.perl.org/perlop.html">the
6815 <literal>s///</literal> operator's syntax</ulink> and <ulink
6816 url="http://perldoc.perl.org/perlre.html">Perl-style regular
6817 expressions</ulink> in general.
6818 The below examples might also help to get you started.
6822 <!-- ~~~~~~~~ New section Header ~~~~~~~~~ -->
6824 <sect2 id="filter-file-tut"><title>Filter File Tutorial</title>
6826 Now, let's complete our <quote>foo</quote> content filter. We have already defined
6827 the heading, but the jobs are still missing. Since all it does is to replace
6828 <quote>foo</quote> with <quote>bar</quote>, there is only one (trivial) job
6833 <screen>s/foo/bar/</screen>
6837 But wait! Didn't the comment say that <emphasis>all</emphasis> occurrences
6838 of <quote>foo</quote> should be replaced? Our current job will only take
6839 care of the first <quote>foo</quote> on each page. For global substitution,
6840 we'll need to add the <literal>g</literal> option:
6844 <screen>s/foo/bar/g</screen>
6848 Our complete filter now looks like this:
6851 <screen>FILTER: foo Replace all "foo" with "bar"
6852 s/foo/bar/g</screen>
6856 Let's look at some real filters for more interesting examples. Here you see
6857 a filter that protects against some common annoyances that arise from JavaScript
6858 abuse. Let's look at its jobs one after the other:
6864 FILTER: js-annoyances Get rid of particularly annoying JavaScript abuse
6866 # Get rid of JavaScript referrer tracking. Test page: http://www.randomoddness.com/untitled.htm
6868 s|(<script.*)document\.referrer(.*</script>)|$1"Not Your Business!"$2|Usg</screen>
6872 Following the header line and a comment, you see the job. Note that it uses
6873 <literal>|</literal> as the delimiter instead of <literal>/</literal>, because
6874 the pattern contains a forward slash, which would otherwise have to be escaped
6875 by a backslash (<literal>\</literal>).
6879 Now, let's examine the pattern: it starts with the text <literal><script.*</literal>
6880 enclosed in parentheses. Since the dot matches any character, and <literal>*</literal>
6881 means: <quote>Match an arbitrary number of the element left of myself</quote>, this
6882 matches <quote><script</quote>, followed by <emphasis>any</emphasis> text, i.e.
6883 it matches the whole page, from the start of the first <script> tag.
6887 That's more than we want, but the pattern continues: <literal>document\.referrer</literal>
6888 matches only the exact string <quote>document.referrer</quote>. The dot needed to
6889 be <emphasis>escaped</emphasis>, i.e. preceded by a backslash, to take away its
6890 special meaning as a joker, and make it just a regular dot. So far, the meaning is:
6891 Match from the start of the first <script> tag in a the page, up to, and including,
6892 the text <quote>document.referrer</quote>, if <emphasis>both</emphasis> are present
6893 in the page (and appear in that order).
6897 But there's still more pattern to go. The next element, again enclosed in parentheses,
6898 is <literal>.*</script></literal>. You already know what <literal>.*</literal>
6899 means, so the whole pattern translates to: Match from the start of the first <script>
6900 tag in a page to the end of the last <script> tag, provided that the text
6901 <quote>document.referrer</quote> appears somewhere in between.
6905 This is still not the whole story, since we have ignored the options and the parentheses:
6906 The portions of the page matched by sub-patterns that are enclosed in parentheses, will be
6907 remembered and be available through the variables <literal>$1, $2, ...</literal> in
6908 the substitute. The <literal>U</literal> option switches to ungreedy matching, which means
6909 that the first <literal>.*</literal> in the pattern will only <quote>eat up</quote> all
6910 text in between <quote><script</quote> and the <emphasis>first</emphasis> occurrence
6911 of <quote>document.referrer</quote>, and that the second <literal>.*</literal> will
6912 only span the text up to the <emphasis>first</emphasis> <quote></script></quote>
6913 tag. Furthermore, the <literal>s</literal> option says that the match may span
6914 multiple lines in the page, and the <literal>g</literal> option again means that the
6915 substitution is global.
6919 So, to summarize, the pattern means: Match all scripts that contain the text
6920 <quote>document.referrer</quote>. Remember the parts of the script from
6921 (and including) the start tag up to (and excluding) the string
6922 <quote>document.referrer</quote> as <literal>$1</literal>, and the part following
6923 that string, up to and including the closing tag, as <literal>$2</literal>.
6927 Now the pattern is deciphered, but wasn't this about substituting things? So
6928 lets look at the substitute: <literal>$1"Not Your Business!"$2</literal> is
6929 easy to read: The text remembered as <literal>$1</literal>, followed by
6930 <literal>"Not Your Business!"</literal> (<emphasis>including</emphasis>
6931 the quotation marks!), followed by the text remembered as <literal>$2</literal>.
6932 This produces an exact copy of the original string, with the middle part
6933 (the <quote>document.referrer</quote>) replaced by <literal>"Not Your
6934 Business!"</literal>.
6938 The whole job now reads: Replace <quote>document.referrer</quote> by
6939 <literal>"Not Your Business!"</literal> wherever it appears inside a
6940 <script> tag. Note that this job won't break JavaScript syntax,
6941 since both the original and the replacement are syntactically valid
6942 string objects. The script just won't have access to the referrer
6943 information anymore.
6947 We'll show you two other jobs from the JavaScript taming department, but
6948 this time only point out the constructs of special interest:
6953 # The status bar is for displaying link targets, not pointless blahblah
6955 s/window\.status\s*=\s*(['"]).*?\1/dUmMy=1/ig</screen>
6959 <literal>\s</literal> stands for whitespace characters (space, tab, newline,
6960 carriage return, form feed), so that <literal>\s*</literal> means: <quote>zero
6961 or more whitespace</quote>. The <literal>?</literal> in <literal>.*?</literal>
6962 makes this matching of arbitrary text ungreedy. (Note that the <literal>U</literal>
6963 option is not set). The <literal>['"]</literal> construct means: <quote>a single
6964 <emphasis>or</emphasis> a double quote</quote>. Finally, <literal>\1</literal> is
6965 a back-reference to the first parenthesis just like <literal>$1</literal> above,
6966 with the difference that in the <emphasis>pattern</emphasis>, a backslash indicates
6967 a back-reference, whereas in the <emphasis>substitute</emphasis>, it's the dollar.
6971 So what does this job do? It replaces assignments of single- or double-quoted
6972 strings to the <quote>window.status</quote> object with a dummy assignment
6973 (using a variable name that is hopefully odd enough not to conflict with
6974 real variables in scripts). Thus, it catches many cases where e.g. pointless
6975 descriptions are displayed in the status bar instead of the link target when
6976 you move your mouse over links.
6981 # Kill OnUnload popups. Yummy. Test: http://www.zdnet.com/zdsubs/yahoo/tree/yfs.html
6983 s/(<body [^>]*)onunload(.*>)/$1never$2/iU</screen>
6988 <ulink url="http://www.w3.org/TR/2000/REC-DOM-Level-2-Events-20001113/events.html#Events-eventgroupings-htmlevents">OnUnload
6989 event binding</ulink> in the HTML DOM was a <emphasis>CRIME</emphasis>.
6990 When I close a browser window, I want it to close and die. Basta.
6991 This job replaces the <quote>onunload</quote> attribute in
6992 <quote><body></quote> tags with the dummy word <literal>never</literal>.
6993 Note that the <literal>i</literal> option makes the pattern matching
6994 case-insensitive. Also note that ungreedy matching alone doesn't always guarantee
6995 a minimal match: In the first parenthesis, we had to use <literal>[^>]*</literal>
6996 instead of <literal>.*</literal> to prevent the match from exceeding the
6997 <body> tag if it doesn't contain <quote>OnUnload</quote>, but the page's
7002 The last example is from the fun department:
7007 FILTER: fun Fun text replacements
7009 # Spice the daily news:
7011 s/microsoft(?!\.com)/MicroSuck/ig</screen>
7015 Note the <literal>(?!\.com)</literal> part (a so-called negative lookahead)
7016 in the job's pattern, which means: Don't match, if the string
7017 <quote>.com</quote> appears directly following <quote>microsoft</quote>
7018 in the page. This prevents links to microsoft.com from being trashed, while
7019 still replacing the word everywhere else.
7024 # Buzzword Bingo (example for extended regex syntax)
7026 s* industry[ -]leading \
7028 | customer[ -]focused \
7029 | market[ -]driven \
7030 | award[ -]winning # Comments are OK, too! \
7031 | high[ -]performance \
7032 | solutions[ -]based \
7036 *<font color="red"><b>BINGO!</b></font> \
7041 The <literal>x</literal> option in this job turns on extended syntax, and allows for
7042 e.g. the liberal use of (non-interpreted!) whitespace for nicer formatting.
7050 <!-- ~~~~~~~~ New section Header ~~~~~~~~~ -->
7052 <sect2 id="predefined-filters"><title>The Pre-defined Filters</title>
7056 Note each filter is also listed in the +filter action section above. Please
7057 keep these listings in sync.
7062 The distribution <filename>default.filter</filename> file contains a selection of
7063 pre-defined filters for your convenience:
7068 <term><emphasis>js-annoyances</emphasis></term>
7071 The purpose of this filter is to get rid of particularly annoying JavaScript abuse.
7076 replaces JavaScript references to the browser's referrer information
7077 with the string "Not Your Business!". This compliments the <literal><link
7078 linkend="hide-referrer">hide-referrer</link></literal> action on the content level.
7083 removes the bindings to the DOM's
7084 <ulink url="http://www.w3.org/TR/2000/REC-DOM-Level-2-Events-20001113/events.html#Events-eventgroupings-htmlevents">unload
7085 event</ulink> which we feel has no right to exist and is responsible for most <quote>exit consoles</quote>, i.e.
7086 nasty windows that pop up when you close another one.
7091 removes code that causes new windows to be opened with undesired properties, such as being
7092 full-screen, non-resizeable, without location, status or menu bar etc.
7098 Use with caution. This is an aggressive filter, and can break sites that
7099 rely heavily on JavaScript.
7105 <term><emphasis>js-events</emphasis></term>
7108 This is a very radical measure. It removes virtually all JavaScript event bindings, which
7109 means that scripts can not react to user actions such as mouse movements or clicks, window
7110 resizing etc, anymore. Use with caution!
7113 We <emphasis>strongly discourage</emphasis> using this filter as a default since it breaks
7114 many legitimate scripts. It is meant for use only on extra-nasty sites (should you really
7121 <term><emphasis>html-annoyances</emphasis></term>
7124 This filter will undo many common instances of HTML based abuse.
7127 The <literal>BLINK</literal> and <literal>MARQUEE</literal> tags
7128 are neutralized (yeah baby!), and browser windows will be created as
7129 resizeable (as of course they should be!), and will have location,
7130 scroll and menu bars -- even if specified otherwise.
7136 <term><emphasis>content-cookies</emphasis></term>
7139 Most cookies are set in the HTTP dialog, where they can be intercepted
7141 <literal><link linkend="crunch-incoming-cookies">crunch-incoming-cookies</link></literal>
7142 and <literal><link linkend="crunch-outgoing-cookies">crunch-outgoing-cookies</link></literal>
7143 actions. But web sites increasingly make use of HTML meta tags and JavaScript
7144 to sneak cookies to the browser on the content level.
7147 This filter disables most HTML and JavaScript code that reads or sets
7148 cookies. It cannot detect all clever uses of these types of code, so it
7149 should not be relied on as an absolute fix. Use it wherever you would also
7150 use the cookie crunch actions.
7156 <term><emphasis>refresh-tags</emphasis></term>
7159 Disable any refresh tags if the interval is greater than nine seconds (so
7160 that redirections done via refresh tags are not destroyed). This is useful
7161 for dial-on-demand setups, or for those who find this HTML feature
7168 <term><emphasis>unsolicited-popups</emphasis></term>
7171 This filter attempts to prevent only <quote>unsolicited</quote> pop-up
7172 windows from opening, yet still allow pop-up windows that the user
7173 has explicitly chosen to open. It was added in version 3.0.1,
7174 as an improvement over earlier such filters.
7177 Technical note: The filter works by redefining the window.open JavaScript
7178 function to a dummy function, <literal>PrivoxyWindowOpen()</literal>,
7179 during the loading and rendering phase of each HTML page access, and
7180 restoring the function afterward.
7183 This is recommended only for browsers that cannot perform this function
7184 reliably themselves. And be aware that some sites require such windows
7185 in order to function normally. Use with caution.
7191 <term><emphasis>all-popups</emphasis></term>
7194 Attempt to prevent <emphasis>all</emphasis> pop-up windows from opening.
7195 Note this should be used with even more discretion than the above, since
7196 it is more likely to break some sites that require pop-ups for normal
7197 usage. Use with caution.
7203 <term><emphasis>img-reorder</emphasis></term>
7206 This is a helper filter that has no value if used alone. It makes the
7207 <literal>banners-by-size</literal> and <literal>banners-by-link</literal>
7208 (see below) filters more effective and should be enabled together with them.
7214 <term><emphasis>banners-by-size</emphasis></term>
7217 This filter removes image tags purely based on what size they are. Fortunately
7218 for us, many ads and banner images tend to conform to certain standardized
7219 sizes, which makes this filter quite effective for ad stripping purposes.
7222 Occasionally this filter will cause false positives on images that are not ads,
7223 but just happen to be of one of the standard banner sizes.
7226 Recommended only for those who require extreme ad blocking. The default
7227 block rules should catch 95+% of all ads <emphasis>without</emphasis> this filter enabled.
7233 <term><emphasis>banners-by-link</emphasis></term>
7236 This is an experimental filter that attempts to kill any banners if
7237 their URLs seem to point to known or suspected click trackers. It is currently
7238 not of much value and is not recommended for use by default.
7244 <term><emphasis>webbugs</emphasis></term>
7247 Webbugs are small, invisible images (technically 1X1 GIF images), that
7248 are used to track users across websites, and collect information on them.
7249 As an HTML page is loaded by the browser, an embedded image tag causes the
7250 browser to contact a third-party site, disclosing the tracking information
7251 through the requested URL and/or cookies for that third-party domain, without
7252 the user ever becoming aware of the interaction with the third-party site.
7253 HTML-ized spam also uses a similar technique to verify email addresses.
7256 This filter removes the HTML code that loads such <quote>webbugs</quote>.
7262 <term><emphasis>tiny-textforms</emphasis></term>
7265 A rather special-purpose filter that can be used to enlarge textareas (those
7266 multi-line text boxes in web forms) and turn off hard word wrap in them.
7267 It was written for the sourceforge.net tracker system where such boxes are
7268 a nuisance, but it can be handy on other sites, too.
7271 It is not recommended to use this filter as a default.
7277 <term><emphasis>jumping-windows</emphasis></term>
7280 Many consider windows that move, or resize themselves to be abusive. This filter
7281 neutralizes the related JavaScript code. Note that some sites might not display
7282 or behave as intended when using this filter. Use with caution.
7288 <term><emphasis>frameset-borders</emphasis></term>
7291 Some web designers seem to assume that everyone in the world will view their
7292 web sites using the same browser brand and version, screen resolution etc,
7293 because only that assumption could explain why they'd use static frame sizes,
7294 yet prevent their frames from being resized by the user, should they be too
7295 small to show their whole content.
7298 This filter removes the related HTML code. It should only be applied to sites
7305 <term><emphasis>demoronizer</emphasis></term>
7308 Many Microsoft products that generate HTML use non-standard extensions (read:
7309 violations) of the ISO 8859-1 aka Latin-1 character set. This can cause those
7310 HTML documents to display with errors on standard-compliant platforms.
7313 This filter translates the MS-only characters into Latin-1 equivalents.
7314 It is not necessary when using MS products, and will cause corruption of
7315 all documents that use 8-bit character sets other than Latin-1. It's mostly
7316 worthwhile for Europeans on non-MS platforms, if weird garbage characters
7317 sometimes appear on some pages, or user agents that don't correct for this on
7320 My version of Mozilla (ancient) shows litte square boxes for quote
7321 characters, and apostrophes on moronized pages. So many pages have this, I
7322 can read them fine now. HB 08/27/06
7329 <term><emphasis>shockwave-flash</emphasis></term>
7332 A filter for shockwave haters. As the name suggests, this filter strips code
7333 out of web pages that is used to embed shockwave flash objects.
7341 <term><emphasis>quicktime-kioskmode</emphasis></term>
7344 Change HTML code that embeds Quicktime objects so that kioskmode, which
7345 prevents saving, is disabled.
7351 <term><emphasis>fun</emphasis></term>
7354 Text replacements for subversive browsing fun. Make fun of your favorite
7355 Monopolist or play buzzword bingo.
7361 <term><emphasis>crude-parental</emphasis></term>
7364 A demonstration-only filter that shows how <application>Privoxy</application>
7365 can be used to delete web content on a keyword basis.
7371 <term><emphasis>ie-exploits</emphasis></term>
7374 An experimental collection of text replacements to disable malicious HTML and JavaScript
7375 code that exploits known security holes in Internet Explorer.
7378 Presently, it only protects against Nimda and a cross-site scripting bug, and
7379 would need active maintenance to provide more substantial protection.
7385 <term><emphasis>site-specifics</emphasis></term>
7388 Some web sites have very specific problems, the cure for which doesn't apply
7389 anywhere else, or could even cause damage on other sites.
7392 This is a collection of such site-specific cures which should only be applied
7393 to the sites they were intended for, which is what the supplied
7394 <filename>default.action</filename> file does. Users shouldn't need to change
7395 anything regarding this filter.
7401 <term><emphasis>google</emphasis></term>
7404 A CSS based block for Google text ads. Also removes a width limitation
7405 and the toolbar advertisement.
7411 <term><emphasis>yahoo</emphasis></term>
7414 Another CSS based block, this time for Yahoo text ads. And removes
7415 a width limitation as well.
7421 <term><emphasis>msn</emphasis></term>
7424 Another CSS based block, this time for MSN text ads. And removes
7425 tracking URLs, as well as a width limitation.
7431 <term><emphasis>blogspot</emphasis></term>
7434 Cleans up some Blogspot blogs. Read the fine print before using this one!
7437 This filter also intentionally removes some navigation stuff and sets the
7438 page width to 100%. As a result, some rounded <quote>corners</quote> would
7439 appear to early or not at all and as fixing this would require a browser
7440 that understands background-size (CSS3), they are removed instead.
7446 <term><emphasis>xml-to-html</emphasis></term>
7449 Server-header filter to change the Content-Type from xml to html.
7455 <term><emphasis>html-to-xml</emphasis></term>
7458 Server-header filter to change the Content-Type from html to xml.
7464 <term><emphasis>no-ping</emphasis></term>
7467 Removes the non-standard <literal>ping</literal> attribute from
7468 anchor and area HTML tags.
7474 <term><emphasis>hide-tor-exit-notation</emphasis></term>
7477 Client-header filter to remove the <command>Tor</command> exit node notation
7478 found in Host and Referer headers.
7481 If &my-app; and <command>Tor</command> are chained and &my-app;
7482 is configured to use socks4a, one can use <quote>http://www.example.org.foobar.exit/</quote>
7483 to access the host <quote>www.example.org</quote> through the
7484 <command>Tor</command> exit node <quote>foobar</quote>.
7487 As the HTTP client isn't aware of this notation, it treats the
7488 whole string <quote>www.example.org.foobar.exit</quote> as host and uses it
7489 for the <quote>Host</quote> and <quote>Referer</quote> headers. From the
7490 server's point of view the resulting headers are invalid and can cause problems.
7493 An invalid <quote>Referer</quote> header can trigger <quote>hot-linking</quote>
7494 protections, an invalid <quote>Host</quote> header will make it impossible for
7495 the server to find the right vhost (several domains hosted on the same IP address).
7498 This client-header filter removes the <quote>foo.exit</quote> part in those headers
7499 to prevent the mentioned problems. Note that it only modifies
7500 the HTTP headers, it doesn't make it impossible for the server
7501 to detect your <command>Tor</command> exit node based on the IP address
7502 the request is coming from.
7509 <term><emphasis> </emphasis></term>
7522 <!-- ~~~~~~~~ New section Header ~~~~~~~~~ -->
7523 <sect2 id="external-filter-syntax"><title>External filter syntax</title>
7525 External filters are scripts or programs that can modify the content in
7526 case common <literal><link linkend="filter">filters</link></literal>
7527 aren't powerful enough.
7530 External filters can be written in any language the platform &my-app; runs
7534 They are controlled with the
7535 <literal><link linkend="external-filter">external-filter</link></literal> action
7536 and have to be defined in the <literal><link linkend="filterfile">filterfile</link></literal>
7540 The header looks like any other filter, but instead of pcrs jobs, external
7541 filters contain a single job which can be a program or a shell script (which
7542 may call other scripts or programs).
7545 External filters read the content from STDIN and write the rewritten
7547 The environment variables PRIVOXY_URL, PRIVOXY_PATH, PRIVOXY_HOST,
7548 PRIVOXY_ORIGIN, PRIVOXY_LISTEN_ADDRESS can be used to get some details
7549 about the client request.
7552 &my-app; will temporary store the content to filter in the
7553 <literal><link linkend="temporary-directory">temporary-directory</link></literal>.
7557 EXTERNAL-FILTER: cat Pointless example filter that doesn't actually modify the content
7560 # Incorrect reimplementation of the filter above in POSIX shell.
7562 # Note that it's a single job that spans multiple lines, the line
7563 # breaks are not passed to the shell, thus the semicolons are required.
7565 # If the script isn't trivial, it is recommended to put it into an external file.
7567 # In general, writing external filters entirely in POSIX shell is not
7568 # considered a good idea.
7569 EXTERNAL-FILTER: cat2 Pointless example filter that despite its name may actually modify the content
7575 EXTERNAL-FILTER: rotate-image Rotate an image by 180 degree. Test filter with limited value.
7576 /usr/local/bin/convert - -rotate 180 -
7578 EXTERNAL-FILTER: citation-needed Adds a "[citation needed]" tag to an image. The coordinates may need adjustment.
7579 /usr/local/bin/convert - -pointsize 16 -fill white -annotate +17+418 "[citation needed]" -
7585 Currently external filters are executed with &my-app;'s privileges!
7586 Only use external filters you understand and trust.
7590 External filters are experimental and the syntax may change in the future.
7596 <!-- ~ End section ~ -->
7600 <!-- ~~~~~ New section ~~~~~ -->
7602 <sect1 id="templates">
7603 <title>Privoxy's Template Files</title>
7605 All <application>Privoxy</application> built-in pages, i.e. error pages such as the
7606 <ulink url="http://show-the-404-error.page"><quote>404 - No Such Domain</quote>
7607 error page</ulink>, the <ulink
7608 url="http://ads.bannerserver.example.com/nasty-ads/sponsor.html"><quote>BLOCKED</quote>
7610 and all pages of its <ulink url="http://config.privoxy.org/">web-based
7611 user interface</ulink>, are generated from <emphasis>templates</emphasis>.
7612 (<application>Privoxy</application> must be running for the above links to work as
7617 These templates are stored in a subdirectory of the <link linkend="confdir">configuration
7618 directory</link> called <filename>templates</filename>. On Unixish platforms,
7620 <ulink url="file:///etc/privoxy/templates/"><filename>/etc/privoxy/templates/</filename></ulink>.
7624 The templates are basically normal HTML files, but with place-holders (called symbols
7625 or exports), which <application>Privoxy</application> fills at run time. It
7626 is possible to edit the templates with a normal text editor, should you want
7627 to customize them. (<emphasis>Not recommended for the casual
7628 user</emphasis>). Should you create your own custom templates, you should use
7629 the <filename>config</filename> setting <link linkend="templdir">templdir</link>
7630 to specify an alternate location, so your templates do not get overwritten
7634 Note that just like in configuration files, lines starting
7635 with <literal>#</literal> are ignored when the templates are filled in.
7639 The place-holders are of the form <literal>@name@</literal>, and you will
7640 find a list of available symbols, which vary from template to template,
7641 in the comments at the start of each file. Note that these comments are not
7642 always accurate, and that it's probably best to look at the existing HTML
7643 code to find out which symbols are supported and what they are filled in with.
7647 A special application of this substitution mechanism is to make whole
7648 blocks of HTML code disappear when a specific symbol is set. We use this
7649 for many purposes, one of them being to include the beta warning in all
7650 our user interface (CGI) pages when <application>Privoxy</application>
7651 is in an alpha or beta development stage:
7656 <!-- @if-unstable-start -->
7658 ... beta warning HTML code goes here ...
7660 <!-- if-unstable-end@ --></screen>
7664 If the "unstable" symbol is set, everything in between and including
7665 <literal>@if-unstable-start</literal> and <literal>if-unstable-end@</literal>
7666 will disappear, leaving nothing but an empty comment:
7670 <screen><!-- --></screen>
7674 There's also an if-then-else construct and an <literal>#include</literal>
7675 mechanism, but you'll sure find out if you are inclined to edit the
7680 All templates refer to a style located at
7681 <ulink url="http://config.privoxy.org/send-stylesheet"><literal>http://config.privoxy.org/send-stylesheet</literal></ulink>.
7682 This is, of course, locally served by <application>Privoxy</application>
7683 and the source for it can be found and edited in the
7684 <filename>cgi-style.css</filename> template.
7689 <!-- ~ End section ~ -->
7693 <!-- ~~~~~ New section ~~~~~ -->
7695 <sect1 id="contact"><title>Contacting the Developers, Bug Reporting and Feature
7698 <!-- Include contacting.sgml boilerplate: -->
7700 <!-- end boilerplate -->
7704 <!-- ~ End section ~ -->
7707 <!-- ~~~~~ New section ~~~~~ -->
7708 <sect1 id="copyright"><title>Privoxy Copyright, License and History</title>
7710 <!-- Include copyright.sgml: -->
7712 <!-- end copyright -->
7715 <application>Privoxy</application> is free software; you can
7716 redistribute it and/or modify it under the terms of the
7717 <citetitle>GNU General Public License</citetitle>, version 2,
7718 as published by the Free Software Foundation and included in
7722 <!-- ~~~~~ New section ~~~~~ -->
7723 <sect2 id="license"><title>License</title>
7725 <screen><![ RCDATA [ &GPLv2; ]]></screen>
7729 <!-- ~ End section ~ -->
7732 <!-- ~~~~~ New section ~~~~~ -->
7734 <sect2 id="history"><title>History</title>
7735 <!-- Include history.sgml: -->
7737 <!-- end history -->
7740 <sect2 id="authors"><title>Authors</title>
7741 <!-- Include p-authors.sgml: -->
7743 <!-- end authors -->
7748 <!-- ~ End section ~ -->
7751 <!-- ~~~~~ New section ~~~~~ -->
7752 <sect1 id="seealso"><title>See Also</title>
7753 <!-- Include seealso.sgml: -->
7755 <!-- end seealso -->
7760 <!-- ~~~~~ New section ~~~~~ -->
7761 <sect1 id="appendix"><title>Appendix</title>
7764 <!-- ~~~~~ New section ~~~~~ -->
7766 <title>Regular Expressions</title>
7768 <application>Privoxy</application> uses Perl-style <quote>regular
7769 expressions</quote> in its <link linkend="actions-file">actions
7770 files</link> and <link linkend="filter-file">filter file</link>,
7771 through the <ulink url="http://www.pcre.org/">PCRE</ulink> and
7774 <ulink url="http://www.oesterhelt.org/pcrs/">PCRS</ulink> libraries.
7776 <application>PCRS</application> libraries.
7780 If you are reading this, you probably don't understand what <quote>regular
7781 expressions</quote> are, or what they can do. So this will be a very brief
7782 introduction only. A full explanation would require a <ulink
7783 url="http://www.oreilly.com/catalog/regex/">book</ulink> ;-)
7787 Regular expressions provide a language to describe patterns that can be
7788 run against strings of characters (letter, numbers, etc), to see if they
7789 match the string or not. The patterns are themselves (sometimes complex)
7790 strings of literal characters, combined with wild-cards, and other special
7791 characters, called meta-characters. The <quote>meta-characters</quote> have
7792 special meanings and are used to build complex patterns to be matched against.
7793 Perl Compatible Regular Expressions are an especially convenient
7794 <quote>dialect</quote> of the regular expression language.
7798 To make a simple analogy, we do something similar when we use wild-card
7799 characters when listing files with the <command>dir</command> command in DOS.
7800 <literal>*.*</literal> matches all filenames. The <quote>special</quote>
7801 character here is the asterisk which matches any and all characters. We can be
7802 more specific and use <literal>?</literal> to match just individual
7803 characters. So <quote>dir file?.text</quote> would match
7804 <quote>file1.txt</quote>, <quote>file2.txt</quote>, etc. We are pattern
7805 matching, using a similar technique to <quote>regular expressions</quote>!
7809 Regular expressions do essentially the same thing, but are much, much more
7810 powerful. There are many more <quote>special characters</quote> and ways of
7811 building complex patterns however. Let's look at a few of the common ones,
7812 and then some examples:
7817 <emphasis>.</emphasis> - Matches any single character, e.g. <quote>a</quote>,
7818 <quote>A</quote>, <quote>4</quote>, <quote>:</quote>, or <quote>@</quote>.
7820 </simplelist></para>
7824 <emphasis>?</emphasis> - The preceding character or expression is matched ZERO or ONE
7827 </simplelist></para>
7831 <emphasis>+</emphasis> - The preceding character or expression is matched ONE or MORE
7834 </simplelist></para>
7838 <emphasis>*</emphasis> - The preceding character or expression is matched ZERO or MORE
7841 </simplelist></para>
7845 <emphasis>\</emphasis> - The <quote>escape</quote> character denotes that
7846 the following character should be taken literally. This is used where one of the
7847 special characters (e.g. <quote>.</quote>) needs to be taken literally and
7848 not as a special meta-character. Example: <quote>example\.com</quote>, makes
7849 sure the period is recognized only as a period (and not expanded to its
7850 meta-character meaning of any single character).
7852 </simplelist></para>
7856 <emphasis>[ ]</emphasis> - Characters enclosed in brackets will be matched if
7857 any of the enclosed characters are encountered. For instance, <quote>[0-9]</quote>
7858 matches any numeric digit (zero through nine). As an example, we can combine
7859 this with <quote>+</quote> to match any digit one of more times: <quote>[0-9]+</quote>.
7861 </simplelist></para>
7865 <emphasis>( )</emphasis> - parentheses are used to group a sub-expression,
7866 or multiple sub-expressions.
7868 </simplelist></para>
7872 <emphasis>|</emphasis> - The <quote>bar</quote> character works like an
7873 <quote>or</quote> conditional statement. A match is successful if the
7874 sub-expression on either side of <quote>|</quote> matches. As an example:
7875 <quote>/(this|that) example/</quote> uses grouping and the bar character
7876 and would match either <quote>this example</quote> or <quote>that
7877 example</quote>, and nothing else.
7879 </simplelist></para>
7882 These are just some of the ones you are likely to use when matching URLs with
7883 <application>Privoxy</application>, and is a long way from a definitive
7884 list. This is enough to get us started with a few simple examples which may
7885 be more illuminating:
7889 <emphasis><literal>/.*/banners/.*</literal></emphasis> - A simple example
7890 that uses the common combination of <quote>.</quote> and <quote>*</quote> to
7891 denote any character, zero or more times. In other words, any string at all.
7892 So we start with a literal forward slash, then our regular expression pattern
7893 (<quote>.*</quote>) another literal forward slash, the string
7894 <quote>banners</quote>, another forward slash, and lastly another
7895 <quote>.*</quote>. We are building
7896 a directory path here. This will match any file with the path that has a
7897 directory named <quote>banners</quote> in it. The <quote>.*</quote> matches
7898 any characters, and this could conceivably be more forward slashes, so it
7899 might expand into a much longer looking path. For example, this could match:
7900 <quote>/eye/hate/spammers/banners/annoy_me_please.gif</quote>, or just
7901 <quote>/banners/annoying.html</quote>, or almost an infinite number of other
7902 possible combinations, just so it has <quote>banners</quote> in the path
7907 And now something a little more complex:
7911 <emphasis><literal>/.*/adv((er)?ts?|ertis(ing|ements?))?/</literal></emphasis> -
7912 We have several literal forward slashes again (<quote>/</quote>), so we are
7913 building another expression that is a file path statement. We have another
7914 <quote>.*</quote>, so we are matching against any conceivable sub-path, just so
7915 it matches our expression. The only true literal that <emphasis>must
7916 match</emphasis> our pattern is <application>adv</application>, together with
7917 the forward slashes. What comes after the <quote>adv</quote> string is the
7922 Remember the <quote>?</quote> means the preceding expression (either a
7923 literal character or anything grouped with <quote>(...)</quote> in this case)
7924 can exist or not, since this means either zero or one match. So
7925 <quote>((er)?ts?|ertis(ing|ements?))</quote> is optional, as are the
7926 individual sub-expressions: <quote>(er)</quote>,
7927 <quote>(ing|ements?)</quote>, and the <quote>s</quote>. The <quote>|</quote>
7928 means <quote>or</quote>. We have two of those. For instance,
7929 <quote>(ing|ements?)</quote>, can expand to match either <quote>ing</quote>
7930 <emphasis>OR</emphasis> <quote>ements?</quote>. What is being done here, is an
7931 attempt at matching as many variations of <quote>advertisement</quote>, and
7932 similar, as possible. So this would expand to match just <quote>adv</quote>,
7933 or <quote>advert</quote>, or <quote>adverts</quote>, or
7934 <quote>advertising</quote>, or <quote>advertisement</quote>, or
7935 <quote>advertisements</quote>. You get the idea. But it would not match
7936 <quote>advertizements</quote> (with a <quote>z</quote>). We could fix that by
7937 changing our regular expression to:
7938 <quote>/.*/adv((er)?ts?|erti(s|z)(ing|ements?))?/</quote>, which would then match
7943 <emphasis><literal>/.*/advert[0-9]+\.(gif|jpe?g)</literal></emphasis> - Again
7944 another path statement with forward slashes. Anything in the square brackets
7945 <quote>[ ]</quote> can be matched. This is using <quote>0-9</quote> as a
7946 shorthand expression to mean any digit one through nine. It is the same as
7947 saying <quote>0123456789</quote>. So any digit matches. The <quote>+</quote>
7948 means one or more of the preceding expression must be included. The preceding
7949 expression here is what is in the square brackets -- in this case, any digit
7950 one through nine. Then, at the end, we have a grouping: <quote>(gif|jpe?g)</quote>.
7951 This includes a <quote>|</quote>, so this needs to match the expression on
7952 either side of that bar character also. A simple <quote>gif</quote> on one side, and the other
7953 side will in turn match either <quote>jpeg</quote> or <quote>jpg</quote>,
7954 since the <quote>?</quote> means the letter <quote>e</quote> is optional and
7955 can be matched once or not at all. So we are building an expression here to
7956 match image GIF or JPEG type image file. It must include the literal
7957 string <quote>advert</quote>, then one or more digits, and a <quote>.</quote>
7958 (which is now a literal, and not a special character, since it is escaped
7959 with <quote>\</quote>), and lastly either <quote>gif</quote>, or
7960 <quote>jpeg</quote>, or <quote>jpg</quote>. Some possible matches would
7961 include: <quote>//advert1.jpg</quote>,
7962 <quote>/nasty/ads/advert1234.gif</quote>,
7963 <quote>/banners/from/hell/advert99.jpg</quote>. It would not match
7964 <quote>advert1.gif</quote> (no leading slash), or
7965 <quote>/adverts232.jpg</quote> (the expression does not include an
7966 <quote>s</quote>), or <quote>/advert1.jsp</quote> (<quote>jsp</quote> is not
7967 in the expression anywhere).
7971 We are barely scratching the surface of regular expressions here so that you
7972 can understand the default <application>Privoxy</application>
7973 configuration files, and maybe use this knowledge to customize your own
7974 installation. There is much, much more that can be done with regular
7975 expressions. Now that you know enough to get started, you can learn more on
7980 More reading on Perl Compatible Regular expressions:
7981 <ulink url="http://perldoc.perl.org/perlre.html">http://perldoc.perl.org/perlre.html</ulink>
7985 For information on regular expression based substitutions and their applications
7986 in filters, please see the <link linkend="filter-file">filter file tutorial</link>
7991 <!-- ~ End section ~ -->
7994 <!-- ~~~~~ New section ~~~~~ -->
7995 <sect2 id="internal-pages">
7996 <title>Privoxy's Internal Pages</title>
7999 Since <application>Privoxy</application> proxies each requested
8000 web page, it is easy for <application>Privoxy</application> to
8001 trap certain special URLs. In this way, we can talk directly to
8002 <application>Privoxy</application>, and see how it is
8003 configured, see how our rules are being applied, change these
8004 rules and other configuration options, and even turn
8005 <application>Privoxy's</application> filtering off, all with
8010 The URLs listed below are the special ones that allow direct access
8011 to <application>Privoxy</application>. Of course,
8012 <application>Privoxy</application> must be running to access these. If
8013 not, you will get a friendly error message. Internet access is not
8026 <ulink url="http://config.privoxy.org/">http://config.privoxy.org/</ulink>
8030 There is a shortcut: <ulink url="http://p.p/">http://p.p/</ulink> (But it
8031 doesn't provide a fall-back to a real page, in case the request is not
8032 sent through <application>Privoxy</application>)
8038 Show information about the current configuration, including viewing and
8039 editing of actions files:
8043 <ulink url="http://config.privoxy.org/show-status">http://config.privoxy.org/show-status</ulink>
8050 Show the source code version numbers:
8054 <ulink url="http://config.privoxy.org/show-version">http://config.privoxy.org/show-version</ulink>
8061 Show the browser's request headers:
8065 <ulink url="http://config.privoxy.org/show-request">http://config.privoxy.org/show-request</ulink>
8072 Show which actions apply to a URL and why:
8076 <ulink url="http://config.privoxy.org/show-url-info">http://config.privoxy.org/show-url-info</ulink>
8083 Toggle Privoxy on or off. This feature can be turned off/on in the main
8084 <filename>config</filename> file. When toggled <quote>off</quote>, <quote>Privoxy</quote>
8085 continues to run, but only as a pass-through proxy, with no actions taking
8090 <ulink url="http://config.privoxy.org/toggle">http://config.privoxy.org/toggle</ulink>
8094 Short cuts. Turn off, then on:
8098 <ulink url="http://config.privoxy.org/toggle?set=disable">http://config.privoxy.org/toggle?set=disable</ulink>
8103 <ulink url="http://config.privoxy.org/toggle?set=enable">http://config.privoxy.org/toggle?set=enable</ulink>
8114 <!-- ~~~~~ New section ~~~~~ -->
8116 <title>Chain of Events</title>
8118 Let's take a quick look at how some of <application>Privoxy's</application>
8119 core features are triggered, and the ensuing sequence of events when a web
8120 page is requested by your browser:
8127 First, your web browser requests a web page. The browser knows to send
8128 the request to <application>Privoxy</application>, which will in turn,
8129 relay the request to the remote web server after passing the following
8135 <application>Privoxy</application> traps any request for its own internal CGI
8136 pages (e.g <ulink url="http://p.p/">http://p.p/</ulink>) and sends the CGI page back to the browser.
8141 Next, <application>Privoxy</application> checks to see if the URL
8143 linkend="BLOCK"><quote>+block</quote></link> patterns. If
8144 so, the URL is then blocked, and the remote web server will not be contacted.
8145 <link linkend="HANDLE-AS-IMAGE"><quote>+handle-as-image</quote></link>
8147 <link linkend="HANDLE-AS-EMPTY-DOCUMENT"><quote>+handle-as-empty-document</quote></link>
8148 are then checked, and if there is no match, an
8149 HTML <quote>BLOCKED</quote> page is sent back to the browser. Otherwise, if
8150 it does match, an image is returned for the former, and an empty text
8151 document for the latter. The type of image would depend on the setting of
8152 <link linkend="SET-IMAGE-BLOCKER"><quote>+set-image-blocker</quote></link>
8153 (blank, checkerboard pattern, or an HTTP redirect to an image elsewhere).
8158 Untrusted URLs are blocked. If URLs are being added to the
8159 <filename>trust</filename> file, then that is done.
8164 If the URL pattern matches the <link
8165 linkend="FAST-REDIRECTS"><quote>+fast-redirects</quote></link> action,
8166 it is then processed. Unwanted parts of the requested URL are stripped.
8171 Now the rest of the client browser's request headers are processed. If any
8172 of these match any of the relevant actions (e.g. <link
8173 linkend="HIDE-USER-AGENT"><quote>+hide-user-agent</quote></link>,
8174 etc.), headers are suppressed or forged as determined by these actions and
8180 Now the web server starts sending its response back (i.e. typically a web
8186 First, the server headers are read and processed to determine, among other
8187 things, the MIME type (document type) and encoding. The headers are then
8188 filtered as determined by the
8189 <link linkend="CRUNCH-INCOMING-COOKIES"><quote>+crunch-incoming-cookies</quote></link>,
8190 <link linkend="SESSION-COOKIES-ONLY"><quote>+session-cookies-only</quote></link>,
8191 and <link linkend="DOWNGRADE-HTTP-VERSION"><quote>+downgrade-http-version</quote></link>
8197 If any <link linkend="FILTER"><quote>+filter</quote></link> action
8199 linkend="DEANIMATE-GIFS"><quote>+deanimate-gifs</quote></link>
8200 action applies (and the document type fits the action), the rest of the page is
8201 read into memory (up to a configurable limit). Then the filter rules (from
8202 <filename>default.filter</filename> and any other filter files) are
8203 processed against the buffered content. Filters are applied in the order
8204 they are specified in one of the filter files. Animated GIFs, if present,
8205 are reduced to either the first or last frame, depending on the action
8206 setting.The entire page, which is now filtered, is then sent by
8207 <application>Privoxy</application> back to your browser.
8210 If neither a <link linkend="FILTER"><quote>+filter</quote></link> action
8212 linkend="DEANIMATE-GIFS"><quote>+deanimate-gifs</quote></link>
8213 matches, then <application>Privoxy</application> passes the raw data through
8214 to the client browser as it becomes available.
8219 As the browser receives the now (possibly filtered) page content, it
8220 reads and then requests any URLs that may be embedded within the page
8221 source, e.g. ad images, stylesheets, JavaScript, other HTML documents (e.g.
8222 frames), sounds, etc. For each of these objects, the browser issues a
8223 separate request (this is easily viewable in <application>Privoxy's</application>
8224 logs). And each such request is in turn processed just as above. Note that a
8225 complex web page will have many, many such embedded URLs. If these
8226 secondary requests are to a different server, then quite possibly a very
8227 differing set of actions is triggered.
8234 NOTE: This is somewhat of a simplistic overview of what happens with each URL
8235 request. For the sake of brevity and simplicity, we have focused on
8236 <application>Privoxy's</application> core features only.
8242 <!-- ~~~~~ New section ~~~~~ -->
8243 <sect2 id="actionsanat">
8244 <title>Troubleshooting: Anatomy of an Action</title>
8247 The way <application>Privoxy</application> applies
8248 <link linkend="ACTIONS">actions</link> and <link linkend="FILTER">filters</link>
8249 to any given URL can be complex, and not always so
8250 easy to understand what is happening. And sometimes we need to be able to
8251 <emphasis>see</emphasis> just what <application>Privoxy</application> is
8252 doing. Especially, if something <application>Privoxy</application> is doing
8253 is causing us a problem inadvertently. It can be a little daunting to look at
8254 the actions and filters files themselves, since they tend to be filled with
8255 <link linkend="regex">regular expressions</link> whose consequences are not
8260 One quick test to see if <application>Privoxy</application> is causing a problem
8261 or not, is to disable it temporarily. This should be the first troubleshooting
8262 step (be sure to flush caches afterward!). Looking at the
8263 logs is a good idea too. (Note that both the toggle feature and logging are
8264 enabled via <filename>config</filename> file settings, and may need to be
8265 turned <quote>on</quote>.)
8268 Another easy troubleshooting step to try is if you have done any
8269 customization of your installation, revert back to the installed
8270 defaults and see if that helps. There are times the developers get complaints
8271 about one thing or another, and the problem is more related to a customized
8272 configuration issue.
8276 <application>Privoxy</application> also provides the
8277 <ulink url="http://config.privoxy.org/show-url-info">http://config.privoxy.org/show-url-info</ulink>
8278 page that can show us very specifically how <application>actions</application>
8279 are being applied to any given URL. This is a big help for troubleshooting.
8283 First, enter one URL (or partial URL) at the prompt, and then
8284 <application>Privoxy</application> will tell us
8285 how the current configuration will handle it. This will not
8286 help with filtering effects (i.e. the <link
8287 linkend="FILTER"><quote>+filter</quote></link> action) from
8288 one of the filter files since this is handled very
8289 differently and not so easy to trap! It also will not tell you about any other
8290 URLs that may be embedded within the URL you are testing. For instance, images
8291 such as ads are expressed as URLs within the raw page source of HTML pages. So
8292 you will only get info for the actual URL that is pasted into the prompt area
8293 -- not any sub-URLs. If you want to know about embedded URLs like ads, you
8294 will have to dig those out of the HTML source. Use your browser's <quote>View
8295 Page Source</quote> option for this. Or right click on the ad, and grab the
8300 Let's try an example, <ulink url="http://google.com">google.com</ulink>,
8301 and look at it one section at a time in a sample configuration (your real
8302 configuration may vary):
8307 Matches for http://www.google.com:
8309 In file: default.action <guibutton>[ View ]</guibutton> <guibutton>[ Edit ]</guibutton>
8311 {+change-x-forwarded-for{block}
8312 +deanimate-gifs {last}
8313 +fast-redirects {check-decoded-url}
8314 +filter {refresh-tags}
8315 +filter {img-reorder}
8316 +filter {banners-by-size}
8318 +filter {jumping-windows}
8319 +filter {ie-exploits}
8320 +hide-from-header {block}
8321 +hide-referrer {forge}
8322 +session-cookies-only
8323 +set-image-blocker {pattern}
8326 { -session-cookies-only }
8332 In file: user.action <guibutton>[ View ]</guibutton> <guibutton>[ Edit ]</guibutton>
8333 (no matches in this file)
8338 This is telling us how we have defined our
8339 <link linkend="ACTIONS"><quote>actions</quote></link>, and
8340 which ones match for our test case, <quote>google.com</quote>.
8341 Displayed is all the actions that are available to us. Remember,
8342 the <literal>+</literal> sign denotes <quote>on</quote>. <literal>-</literal>
8343 denotes <quote>off</quote>. So some are <quote>on</quote> here, but many
8344 are <quote>off</quote>. Each example we try may provide a slightly different
8345 end result, depending on our configuration directives.
8349 is for our <filename>default.action</filename> file. The large, multi-line
8350 listing, is how the actions are set to match for all URLs, i.e. our default
8351 settings. If you look at your <quote>actions</quote> file, this would be the
8352 section just below the <quote>aliases</quote> section near the top. This
8353 will apply to all URLs as signified by the single forward slash at the end
8354 of the listing -- <quote> / </quote>.
8358 But we have defined additional actions that would be exceptions to these general
8359 rules, and then we list specific URLs (or patterns) that these exceptions
8360 would apply to. Last match wins. Just below this then are two explicit
8361 matches for <quote>.google.com</quote>. The first is negating our previous
8362 cookie setting, which was for <link
8363 linkend="SESSION-COOKIES-ONLY"><quote>+session-cookies-only</quote></link>
8364 (i.e. not persistent). So we will allow persistent cookies for google, at
8365 least that is how it is in this example. The second turns
8366 <emphasis>off</emphasis> any <link
8367 linkend="FAST-REDIRECTS"><quote>+fast-redirects</quote></link>
8368 action, allowing this to take place unmolested. Note that there is a leading
8369 dot here -- <quote>.google.com</quote>. This will match any hosts and
8370 sub-domains, in the google.com domain also, such as
8371 <quote>www.google.com</quote> or <quote>mail.google.com</quote>. But it would not
8372 match <quote>www.google.de</quote>! So, apparently, we have these two actions
8373 defined as exceptions to the general rules at the top somewhere in the lower
8374 part of our <filename>default.action</filename> file, and
8375 <quote>google.com</quote> is referenced somewhere in these latter sections.
8379 Then, for our <filename>user.action</filename> file, we again have no hits.
8380 So there is nothing google-specific that we might have added to our own, local
8381 configuration. If there was, those actions would over-rule any actions from
8382 previously processed files, such as <filename>default.action</filename>.
8383 <filename>user.action</filename> typically has the last word. This is the
8384 best place to put hard and fast exceptions,
8388 And finally we pull it all together in the bottom section and summarize how
8389 <application>Privoxy</application> is applying all its <quote>actions</quote>
8390 to <quote>google.com</quote>:
8399 +change-x-forwarded-for{block}
8400 -client-header-filter{hide-tor-exit-notation}
8401 -content-type-overwrite
8402 -crunch-client-header
8403 -crunch-if-none-match
8404 -crunch-incoming-cookies
8405 -crunch-outgoing-cookies
8406 -crunch-server-header
8407 +deanimate-gifs {last}
8408 -downgrade-http-version
8411 -filter {content-cookies}
8412 -filter {all-popups}
8413 -filter {banners-by-link}
8414 -filter {tiny-textforms}
8415 -filter {frameset-borders}
8416 -filter {demoronizer}
8417 -filter {shockwave-flash}
8418 -filter {quicktime-kioskmode}
8420 -filter {crude-parental}
8421 -filter {site-specifics}
8422 -filter {js-annoyances}
8423 -filter {html-annoyances}
8424 +filter {refresh-tags}
8425 -filter {unsolicited-popups}
8426 +filter {img-reorder}
8427 +filter {banners-by-size}
8429 +filter {jumping-windows}
8430 +filter {ie-exploits}
8437 -handle-as-empty-document
8439 -hide-accept-language
8440 -hide-content-disposition
8441 +hide-from-header {block}
8442 -hide-if-modified-since
8443 +hide-referrer {forge}
8446 -overwrite-last-modified
8447 -prevent-compression
8449 -server-header-filter{xml-to-html}
8450 -server-header-filter{html-to-xml}
8451 -session-cookies-only
8452 +set-image-blocker {pattern} </screen>
8456 Notice the only difference here to the previous listing, is to
8457 <quote>fast-redirects</quote> and <quote>session-cookies-only</quote>,
8458 which are activated specifically for this site in our configuration,
8459 and thus show in the <quote>Final Results</quote>.
8463 Now another example, <quote>ad.doubleclick.net</quote>:
8468 { +block{Domains starts with "ad"} }
8471 { +block{Domain contains "ad"} }
8474 { +block{Doubleclick banner server} +handle-as-image }
8475 .[a-vx-z]*.doubleclick.net
8480 We'll just show the interesting part here - the explicit matches. It is
8481 matched three different times. Two <quote>+block{}</quote> sections,
8482 and a <quote>+block{} +handle-as-image</quote>,
8483 which is the expanded form of one of our aliases that had been defined as:
8484 <quote>+block-as-image</quote>. (<link
8485 linkend="ALIASES"><quote>Aliases</quote></link> are defined in
8486 the first section of the actions file and typically used to combine more
8491 Any one of these would have done the trick and blocked this as an unwanted
8492 image. This is unnecessarily redundant since the last case effectively
8493 would also cover the first. No point in taking chances with these guys
8494 though ;-) Note that if you want an ad or obnoxious
8495 URL to be invisible, it should be defined as <quote>ad.doubleclick.net</quote>
8496 is done here -- as both a <link
8497 linkend="BLOCK"><quote>+block{}</quote></link>
8498 <emphasis>and</emphasis> an
8499 <link linkend="HANDLE-AS-IMAGE"><quote>+handle-as-image</quote></link>.
8500 The custom alias <quote><literal>+block-as-image</literal></quote> just
8501 simplifies the process and make it more readable.
8505 One last example. Let's try <quote>http://www.example.net/adsl/HOWTO/</quote>.
8506 This one is giving us problems. We are getting a blank page. Hmmm ...
8511 Matches for http://www.example.net/adsl/HOWTO/:
8513 In file: default.action <guibutton>[ View ]</guibutton> <guibutton>[ Edit ]</guibutton>
8517 +change-x-forwarded-for{block}
8518 -client-header-filter{hide-tor-exit-notation}
8519 -content-type-overwrite
8520 -crunch-client-header
8521 -crunch-if-none-match
8522 -crunch-incoming-cookies
8523 -crunch-outgoing-cookies
8524 -crunch-server-header
8526 -downgrade-http-version
8527 +fast-redirects {check-decoded-url}
8529 -filter {content-cookies}
8530 -filter {all-popups}
8531 -filter {banners-by-link}
8532 -filter {tiny-textforms}
8533 -filter {frameset-borders}
8534 -filter {demoronizer}
8535 -filter {shockwave-flash}
8536 -filter {quicktime-kioskmode}
8538 -filter {crude-parental}
8539 -filter {site-specifics}
8540 -filter {js-annoyances}
8541 -filter {html-annoyances}
8542 +filter {refresh-tags}
8543 -filter {unsolicited-popups}
8544 +filter {img-reorder}
8545 +filter {banners-by-size}
8547 +filter {jumping-windows}
8548 +filter {ie-exploits}
8555 -handle-as-empty-document
8557 -hide-accept-language
8558 -hide-content-disposition
8559 +hide-from-header{block}
8560 +hide-referer{forge}
8562 -overwrite-last-modified
8563 +prevent-compression
8565 -server-header-filter{xml-to-html}
8566 -server-header-filter{html-to-xml}
8567 +session-cookies-only
8568 +set-image-blocker{blank} }
8571 { +block{Path contains "ads".} +handle-as-image }
8577 Ooops, the <quote>/adsl/</quote> is matching <quote>/ads</quote> in our
8578 configuration! But we did not want this at all! Now we see why we get the
8579 blank page. It is actually triggering two different actions here, and
8580 the effects are aggregated so that the URL is blocked, and &my-app; is told
8581 to treat the block as if it were an image. But this is, of course, all wrong.
8582 We could now add a new action below this (or better in our own
8583 <filename>user.action</filename> file) that explicitly
8584 <emphasis>un</emphasis> blocks (
8585 <link linkend="BLOCK"><quote>{-block}</quote></link>) paths with
8586 <quote>adsl</quote> in them (remember, last match in the configuration
8587 wins). There are various ways to handle such exceptions. Example:
8598 Now the page displays ;-)
8599 Remember to flush your browser's caches when making these kinds of changes to
8600 your configuration to insure that you get a freshly delivered page! Or, try
8601 using <literal>Shift+Reload</literal>.
8605 But now what about a situation where we get no explicit matches like
8611 { +block{Path starts with "ads".} +handle-as-image }
8617 That actually was very helpful and pointed us quickly to where the problem
8618 was. If you don't get this kind of match, then it means one of the default
8619 rules in the first section of <filename>default.action</filename> is causing
8620 the problem. This would require some guesswork, and maybe a little trial and
8621 error to isolate the offending rule. One likely cause would be one of the
8622 <link linkend="FILTER"><quote>+filter</quote></link> actions.
8623 These tend to be harder to troubleshoot.
8624 Try adding the URL for the site to one of aliases that turn off
8625 <link linkend="FILTER"><quote>+filter</quote></link>:
8632 .worldpay.com # for quietpc.com
8640 <quote><literal>{ shop }</literal></quote> is an <quote>alias</quote> that expands to
8641 <quote><literal>{ -filter -session-cookies-only }</literal></quote>.
8642 Or you could do your own exception to negate filtering:
8648 # Disable ALL filter actions for sites in this section
8656 This would turn off all filtering for these sites. This is best
8657 put in <filename>user.action</filename>, for local site
8658 exceptions. Note that when a simple domain pattern is used by itself (without
8659 the subsequent path portion), all sub-pages within that domain are included
8660 automatically in the scope of the action.
8664 Images that are inexplicably being blocked, may well be hitting the
8665 <link linkend="FILTER-BANNERS-BY-SIZE"><quote>+filter{banners-by-size}</quote></link>
8667 that images of certain sizes are ad banners (works well
8668 <emphasis>most of the time</emphasis> since these tend to be standardized).
8672 <quote><literal>{ fragile }</literal></quote> is an alias that disables most
8673 actions that are the most likely to cause trouble. This can be used as a
8674 last resort for problem sites.
8679 # Handle with care: easy to break
8681 mybank.example.com</screen>
8686 <emphasis>Remember to flush caches!</emphasis> Note that the
8687 <literal>mail.google</literal> reference lacks the TLD portion (e.g.
8688 <quote>.com</quote>). This will effectively match any TLD with
8689 <literal>google</literal> in it, such as <literal>mail.google.de.</literal>,
8693 If this still does not work, you will have to go through the remaining
8694 actions one by one to find which one(s) is causing the problem.
8703 This program is free software; you can redistribute it
8704 and/or modify it under the terms of the GNU General
8705 Public License as published by the Free Software
8706 Foundation; either version 2 of the License, or (at
8707 your option) any later version.
8709 This program is distributed in the hope that it will
8710 be useful, but WITHOUT ANY WARRANTY; without even the
8711 implied warranty of MERCHANTABILITY or FITNESS FOR A
8712 PARTICULAR PURPOSE. See the GNU General Public
8713 License for more details.
8715 The GNU General Public License should be included with
8716 this file. If not, you can view it at
8717 http://www.gnu.org/copyleft/gpl.html
8718 or write to the Free Software Foundation, Inc.,
8719 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
projects / privoxy.git / blob