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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13 <!entity p-authors SYSTEM "p-authors.sgml">
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15 <!entity changelog SYSTEM "changelog.sgml">
16 <!entity p-version "3.0.27">
17 <!entity p-status "UNRELEASED">
18 <!entity % p-authors-formal "INCLUDE"> <!-- include additional text, etc -->
19 <!entity % p-not-stable "INCLUDE">
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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>:
416 The recommended way to upgrade &my-app; is to backup your old
417 configuration files, install the new ones, verify that &my-app;
418 is working correctly and finally merge back your changes using
419 <application>diff</application> and maybe <application>patch</application>.
422 There are a number of new features in each &my-app; release and
423 most of them have to be explicitly enabled in the configuration
424 files. Old configuration files obviously don't do that and due
425 to syntax changes using old configuration files with a new
426 &my-app; isn't always possible anyway.
431 Note that some installers remove earlier versions completely,
432 including configuration files, therefore you should really save
433 any important configuration files!
438 On the other hand, other installers don't overwrite existing configuration
439 files, thinking you will want to do that yourself.
444 In the default configuration only fatal errors are logged now.
445 You can change that in the <link linkend="DEBUG">debug section</link>
446 of the configuration file. You may also want to enable more verbose
447 logging until you verified that the new &my-app; version is working
454 Three other config file settings are now off by default:
455 <link linkend="enable-remote-toggle">enable-remote-toggle</link>,
456 <link linkend="enable-remote-http-toggle">enable-remote-http-toggle</link>,
457 and <link linkend="enable-edit-actions">enable-edit-actions</link>.
458 If you use or want these, you will need to explicitly enable them, and
459 be aware of the security issues involved.
466 What constitutes a <quote>default</quote> configuration has changed,
467 and you may want to review which actions are <quote>on</quote> by
468 default. This is primarily a matter of emphasis, but some features
469 you may have been used to, may now be <quote>off</quote> by default.
470 There are also a number of new actions and filters you may want to
471 consider, most of which are not fully incorporated into the default
472 settings as yet (see above).
479 The default actions setting is now <literal>Cautious</literal>. Previous
480 releases had a default setting of <literal>Medium</literal>. Experienced
481 users may want to adjust this, as it is fairly conservative by &my-app;
482 standards and past practices. See <ulink
483 url="http://config.privoxy.org/edit-actions-list?f=default">
484 http://config.privoxy.org/edit-actions-list?f=default</ulink>. New users
485 should try the default settings for a while before turning up the volume.
491 The default setting has filtering turned <emphasis>off</emphasis>, which
492 subsequently means that compression is <emphasis>on</emphasis>. Remember
493 that filtering does not work on compressed pages, so if you use, or want to
494 use, filtering, you will need to force compression off. Example:
497 { +<link linkend="filter">filter</link>{google} +<link linkend="prevent-compression">prevent-compression</link> }
500 Or if you use a number of filters, or filter many sites, you may just want
501 to turn off compression for all sites in
502 <filename>default.action</filename> (or
503 <filename>user.action</filename>).
510 Also, <link linkend="SESSION-COOKIES-ONLY">session-cookies-only</link> is
511 off by default now. If you've liked this feature in the past, you may want
512 to turn it back on in <filename>user.action</filename> now.
519 Some installers may not automatically start
520 <application>Privoxy</application> after installation.
530 <!-- ~~~~~ New section ~~~~~ -->
531 <sect1 id="quickstart"><title>Quickstart to Using Privoxy</title>
537 Install <application>Privoxy</application>. See the <link
538 linkend="installation">Installation Section</link> below for platform specific
545 Advanced users and those who want to offer <application>Privoxy</application>
546 service to more than just their local machine should check the <link
547 linkend="config">main config file</link>, especially the <link
548 linkend="access-control">security-relevant</link> options. These are
555 Start <application>Privoxy</application>, if the installation program has
556 not done this already (may vary according to platform). See the section
557 <link linkend="startup">Starting <application>Privoxy</application></link>.
563 Set your browser to use <application>Privoxy</application> as HTTP and
564 HTTPS (SSL) <ulink url="http://en.wikipedia.org/wiki/Proxy_server">proxy</ulink>
565 by setting the proxy configuration for address of
566 <literal>127.0.0.1</literal> and port <literal>8118</literal>.
567 <emphasis>DO NOT</emphasis> activate proxying for <literal>FTP</literal> or
568 any protocols besides HTTP and HTTPS (SSL) unless you intend to prevent your
569 browser from using these protocols.
575 Flush your browser's disk and memory caches, to remove any cached ad images.
576 If using <application>Privoxy</application> to manage
577 <ulink url="http://en.wikipedia.org/wiki/Browser_cookie">cookies</ulink>,
578 you should remove any currently stored cookies too.
584 A default installation should provide a reasonable starting point for
585 most. There will undoubtedly be occasions where you will want to adjust the
586 configuration, but that can be dealt with as the need arises. Little
587 to no initial configuration is required in most cases, you may want
589 <ulink url="config.html#ENABLE-EDIT-ACTIONS">web-based action editor</ulink> though.
590 Be sure to read the warnings first.
593 See the <link linkend="configuration">Configuration section</link> for more
594 configuration options, and how to customize your installation.
595 You might also want to look at the <link
596 linkend="quickstart-ad-blocking">next section</link> for a quick
597 introduction to how <application>Privoxy</application> blocks ads and
604 If you experience ads that slip through, innocent images that are
605 blocked, or otherwise feel the need to fine-tune
606 <application>Privoxy's</application> behavior, take a look at the <link
607 linkend="actions-file">actions files</link>. As a quick start, you might
608 find the <link linkend="act-examples">richly commented examples</link>
609 helpful. You can also view and edit the actions files through the <ulink
610 url="http://config.privoxy.org">web-based user interface</ulink>. The
611 Appendix <quote><link linkend="actionsanat">Troubleshooting: Anatomy of an
612 Action</link></quote> has hints on how to understand and debug actions that
613 <quote>misbehave</quote>.
619 Please see the section <link linkend="contact">Contacting the
620 Developers</link> on how to report bugs, problems with websites or to get
627 Now enjoy surfing with enhanced control, comfort and privacy!
634 <!-- ~~~~~ New section ~~~~~ -->
636 <sect2 id="quickstart-ad-blocking">
637 <title>Quickstart to Ad Blocking</title>
639 NOTE: This section is deliberately redundant for those that don't
640 want to read the whole thing (which is getting lengthy).
643 Ad blocking is but one of <application>Privoxy's</application>
644 array of features. Many of these features are for the technically minded advanced
645 user. But, ad and banner blocking is surely common ground for everybody.
648 This section will provide a quick summary of ad blocking so
649 you can get up to speed quickly without having to read the more extensive
650 information provided below, though this is highly recommended.
653 First a bit of a warning ... blocking ads is much like blocking SPAM: the
654 more aggressive you are about it, the more likely you are to block
655 things that were not intended. And the more likely that some things
656 may not work as intended. So there is a trade off here. If you want
657 extreme ad free browsing, be prepared to deal with more
658 <quote>problem</quote> sites, and to spend more time adjusting the
659 configuration to solve these unintended consequences. In short, there is
660 not an easy way to eliminate <emphasis>all</emphasis> ads. Either take
661 the easy way and settle for <emphasis>most</emphasis> ads blocked with the
662 default configuration, or jump in and tweak it for your personal surfing
663 habits and preferences.
666 Secondly, a brief explanation of <application>Privoxy's </application>
667 <quote>actions</quote>. <quote>Actions</quote> in this context, are
668 the directives we use to tell <application>Privoxy</application> to perform
669 some task relating to HTTP transactions (i.e. web browsing). We tell
670 <application>Privoxy</application> to take some <quote>action</quote>. Each
671 action has a unique name and function. While there are many potential
672 <application>actions</application> in <application>Privoxy's</application>
673 arsenal, only a few are used for ad blocking. <link
674 linkend="actions">Actions</link>, and <link linkend="actions-file">action
675 configuration files</link>, are explained in depth below.
678 Actions are specified in <application>Privoxy's</application> configuration,
679 followed by one or more URLs to which the action should apply. URLs
680 can actually be URL type <link linkend="af-patterns">patterns</link> that use
681 wildcards so they can apply potentially to a range of similar URLs. The
682 actions, together with the URL patterns are called a section.
685 When you connect to a website, the full URL will either match one or more
686 of the sections as defined in <application>Privoxy's</application> configuration,
687 or not. If so, then <application>Privoxy</application> will perform the
688 respective actions. If not, then nothing special happens. Furthermore, web
689 pages may contain embedded, secondary URLs that your web browser will
690 use to load additional components of the page, as it parses the
691 original page's HTML content. An ad image for instance, is just an URL
692 embedded in the page somewhere. The image itself may be on the same server,
693 or a server somewhere else on the Internet. Complex web pages will have many
694 such embedded URLs. &my-app; can deal with each URL individually, so, for
695 instance, the main page text is not touched, but images from such-and-such
700 The most important actions for basic ad blocking are: <literal><link
701 linkend="block">block</link></literal>, <literal><link
702 linkend="handle-as-image">handle-as-image</link></literal>,
704 linkend="handle-as-empty-document">handle-as-empty-document</link></literal>,and
705 <literal><link linkend="set-image-blocker">set-image-blocker</link></literal>:
712 <literal><link linkend="block">block</link></literal> - this is perhaps
713 the single most used action, and is particularly important for ad blocking.
714 This action stops any contact between your browser and any URL patterns
715 that match this action's configuration. It can be used for blocking ads,
716 but also anything that is determined to be unwanted. By itself, it simply
717 stops any communication with the remote server and sends
718 <application>Privoxy</application>'s own built-in BLOCKED page instead to
719 let you now what has happened (with some exceptions, see below).
725 <literal><link linkend="handle-as-image">handle-as-image</link></literal> -
726 tells <application>Privoxy</application> to treat this URL as an image.
727 <application>Privoxy</application>'s default configuration already does this
728 for all common image types (e.g. GIF), but there are many situations where this
729 is not so easy to determine. So we'll force it in these cases. This is particularly
730 important for ad blocking, since only if we know that it's an image of
731 some kind, can we replace it with an image of our choosing, instead of the
732 <application>Privoxy</application> BLOCKED page (which would only result in
733 a <quote>broken image</quote> icon). There are some limitations to this
734 though. For instance, you can't just brute-force an image substitution for
735 an entire HTML page in most situations.
741 <literal><link linkend="handle-as-empty-document">handle-as-empty-document</link></literal> -
742 sends an empty document instead of <application>Privoxy's</application>
743 normal BLOCKED HTML page. This is useful for file types that are neither
744 HTML nor images, such as blocking JavaScript files.
751 linkend="set-image-blocker">set-image-blocker</link></literal> - tells
752 <application>Privoxy</application> what to display in place of an ad image that
753 has hit a block rule. For this to come into play, the URL must match a
754 <literal><link linkend="block">block</link></literal> action somewhere in the
755 configuration, <emphasis>and</emphasis>, it must also match an
756 <literal><link linkend="handle-as-image">handle-as-image</link></literal> action.
759 The configuration options on what to display instead of the ad are:
763 <emphasis>pattern</emphasis> - a checkerboard pattern, so that an ad
764 replacement is obvious. This is the default.
769 <emphasis>blank</emphasis> - A very small empty GIF image is displayed.
770 This is the so-called <quote>invisible</quote> configuration option.
775 <emphasis>http://<URL></emphasis> - A redirect to any image anywhere
776 of the user's choosing (advanced usage).
784 Advanced users will eventually want to explore &my-app;
785 <literal><link linkend="filter">filters</link></literal> as well. Filters
786 are very different from <literal><link
787 linkend="block">blocks</link></literal>.
788 A <quote>block</quote> blocks a site, page, or unwanted contented. Filters
789 are a way of filtering or modifying what is actually on the page. An example
790 filter usage: a text replacement of <quote>no-no</quote> for
791 <quote>nasty-word</quote>. That is a very simple example. This process can be
792 used for ad blocking, but it is more in the realm of advanced usage and has
793 some pitfalls to be wary off.
797 The quickest way to adjust any of these settings is with your browser through
798 the special <application>Privoxy</application> editor at <ulink
799 url="http://config.privoxy.org/show-status">http://config.privoxy.org/show-status</ulink>
800 (shortcut: <ulink url="http://p.p/">http://p.p/show-status</ulink>). This
801 is an internal page, and does not require Internet access.
805 Note that as of <application>Privoxy</application> 3.0.7 beta the
806 action editor is disabled by default. Check the
807 <ulink url="config.html#ENABLE-EDIT-ACTIONS">enable-edit-actions
808 section in the configuration file</ulink> to learn why and in which
809 cases it's safe to enable again.
813 If you decided to enable the action editor, select the appropriate
814 <quote>actions</quote> file, and click
815 <quote><guibutton>Edit</guibutton></quote>. It is best to put personal or
816 local preferences in <filename>user.action</filename> since this is not
817 meant to be overwritten during upgrades, and will over-ride the settings in
818 other files. Here you can insert new <quote>actions</quote>, and URLs for ad
819 blocking or other purposes, and make other adjustments to the configuration.
820 <application>Privoxy</application> will detect these changes automatically.
824 A quick and simple step by step example:
831 Right click on the ad image to be blocked, then select
832 <quote><guimenuitem>Copy Link Location</guimenuitem></quote> from the
840 url="http://config.privoxy.org/show-status">http://config.privoxy.org/show-status</ulink>
845 Find <filename>user.action</filename> in the top section, and click
846 on <quote><guibutton>Edit</guibutton></quote>:
849 <!-- image of editor and actions files selections -->
850 <figure pgwide="0" float="0"><title>Actions Files in Use</title>
853 <imagedata fileref="files-in-use.jpg" format="jpg">
856 <phrase>[ Screenshot of Actions Files in Use ]</phrase>
864 You should have a section with only
865 <literal><link linkend="block">block</link></literal> listed under
866 <quote>Actions:</quote>.
867 If not, click a <quote><guibutton>Insert new section below</guibutton></quote>
868 button, and in the new section that just appeared, click the
869 <guibutton>Edit</guibutton> button right under the word <quote>Actions:</quote>.
870 This will bring up a list of all actions. Find
871 <literal><link linkend="block">block</link></literal> near the top, and click
872 in the <quote>Enabled</quote> column, then <quote><guibutton>Submit</guibutton></quote>
878 Now, in the <literal><link linkend="block">block</link></literal> actions section,
879 click the <quote><guibutton>Add</guibutton></quote> button, and paste the URL the
880 browser got from <quote><guimenuitem>Copy Link Location</guimenuitem></quote>.
881 Remove the <literal>http://</literal> at the beginning of the URL. Then, click
882 <quote><guibutton>Submit</guibutton></quote> (or
883 <quote><guibutton>OK</guibutton></quote> if in a pop-up window).
888 Now go back to the original page, and press <keycap>SHIFT-Reload</keycap>
889 (or flush all browser caches). The image should be gone now.
896 This is a very crude and simple example. There might be good reasons to use a
897 wildcard pattern match to include potentially similar images from the same
898 site. For a more extensive explanation of <quote>patterns</quote>, and
899 the entire actions concept, see <link linkend="actions-file">the Actions
904 For advanced users who want to hand edit their config files, you might want
905 to now go to the <link linkend="act-examples">Actions Files Tutorial</link>.
906 The ideas explained therein also apply to the web-based editor.
909 There are also various
910 <link linkend="filter">filters</link> that can be used for ad blocking
911 (filters are a special subset of actions). These
912 fall into the <quote>advanced</quote> usage category, and are explained in
913 depth in later sections.
920 <!-- ~ End section ~ -->
923 <!-- ~~~~~ New section ~~~~~ -->
925 <title>Starting Privoxy</title>
927 Before launching <application>Privoxy</application> for the first time, you
928 will want to configure your browser(s) to use
929 <application>Privoxy</application> as a HTTP and HTTPS (SSL)
930 <ulink url="http://en.wikipedia.org/wiki/Proxy_server">proxy</ulink>. The default is
931 127.0.0.1 (or localhost) for the proxy address, and port 8118 (earlier versions
932 used port 8000). This is the one configuration step <emphasis>that must be done
936 Please note that <application>Privoxy</application> can only proxy HTTP and
937 HTTPS traffic. It will not work with FTP or other protocols.
940 <!-- image of Mozilla Proxy configuration -->
941 <figure pgwide="0" float="0"><title>Proxy Configuration Showing
942 Mozilla/Netscape HTTP and HTTPS (SSL) Settings</title>
945 <imagedata fileref="proxy_setup.jpg" format="jpg">
948 <phrase>[ Screenshot of Mozilla Proxy Configuration ]</phrase>
955 With <application>Firefox</application>, this is typically set under:
959 <guibutton>Tools</guibutton> -> <guibutton>Options</guibutton> -> <guibutton>Advanced</guibutton> -> <guibutton>Network</guibutton> -><guibutton>Connection</guibutton> -> <guibutton>Settings</guibutton>
963 Or optionally on some platforms:
967 <guibutton>Edit</guibutton> -> <guibutton>Preferences</guibutton> -> <guibutton>General</guibutton> -> <guibutton>Connection Settings</guibutton> -> <guibutton>Manual Proxy Configuration</guibutton>
972 With <application>Netscape</application> (and
973 <application>Mozilla</application>), this can be set under:
978 <!-- Mix ascii and gui art, something for everybody -->
979 <!-- spacing on this is tricky -->
980 <guibutton>Edit</guibutton> -> <guibutton>Preferences</guibutton> -> <guibutton>Advanced</guibutton> -> <guibutton>Proxies</guibutton> -> <guibutton>HTTP Proxy</guibutton>
984 For <application>Internet Explorer v.5-7</application>:
988 <guibutton>Tools</guibutton> -> <guibutton>Internet Options</guibutton> -> <guibutton>Connections</guibutton> -> <guibutton>LAN Settings</guibutton>
992 Then, check <quote>Use Proxy</quote> and fill in the appropriate info
993 (Address: 127.0.0.1, Port: 8118). Include HTTPS (SSL), if you want HTTPS
994 proxy support too (sometimes labeled <quote>Secure</quote>). Make sure any
995 checkboxes like <quote>Use the same proxy server for all protocols</quote> is
996 <emphasis>UNCHECKED</emphasis>. You want only HTTP and HTTPS (SSL)!
999 <!-- image of IE Proxy configuration -->
1000 <figure pgwide="0" float="0"><title>Proxy Configuration Showing
1001 Internet Explorer HTTP and HTTPS (Secure) Settings</title>
1004 <imagedata fileref="proxy2.jpg" format="jpg">
1007 <phrase>[ Screenshot of IE Proxy Configuration ]</phrase>
1014 After doing this, flush your browser's disk and memory caches to force a
1015 re-reading of all pages and to get rid of any ads that may be cached. Remove
1016 any <ulink url="http://en.wikipedia.org/wiki/Browser_cookie">cookies</ulink>,
1017 if you want <application>Privoxy</application> to manage that. You are now
1018 ready to start enjoying the benefits of using
1019 <application>Privoxy</application>!
1023 <application>Privoxy</application> itself is typically started by specifying the
1024 main configuration file to be used on the command line. If no configuration
1025 file is specified on the command line, <application>Privoxy</application>
1026 will look for a file named <filename>config</filename> in the current
1027 directory. Except on Win32 where it will try <filename>config.txt</filename>.
1030 <sect2 id="start-debian">
1031 <title>Debian</title>
1033 We use a script. Note that Debian typically starts &my-app; upon booting per
1034 default. It will use the file
1035 <filename>/etc/privoxy/config</filename> as its main configuration
1039 # /etc/init.d/privoxy start
1043 <sect2 id="start-freebsd">
1044 <title>FreeBSD and ElectroBSD</title>
1046 To start <application>Privoxy</application> upon booting, add
1047 "privoxy_enable='YES'" to <filename>/etc/rc.conf</filename>.
1048 <application>Privoxy</application> will use
1049 <filename>/usr/local/etc/privoxy/config</filename> as its main
1053 If you installed <application>Privoxy</application> into a jail, the
1054 paths above are relative to the jail root.
1057 To start <application>Privoxy</application> manually, run:
1060 # service privoxy onestart
1064 <sect2 id="start-windows">
1065 <title>Windows</title>
1067 Click on the &my-app; Icon to start <application>Privoxy</application>. If no configuration file is
1068 specified on the command line, <application>Privoxy</application> will look
1069 for a file named <filename>config.txt</filename>. Note that Windows will
1070 automatically start &my-app; when the system starts if you chose that option
1074 <application>Privoxy</application> can run with full Windows service functionality.
1075 On Windows only, the &my-app; program has two new command line arguments
1076 to install and uninstall &my-app; as a service. See the
1077 <link linkend="installation-pack-win">Windows Installation
1078 instructions</link> for details.
1082 <sect2 id="start-unices">
1083 <title>Generic instructions for Unix derivates (Solaris, NetBSD, HP-UX etc.)</title>
1085 Example Unix startup command:
1088 # /usr/sbin/privoxy --user privoxy /etc/privoxy/config
1091 Note that if you installed <application>Privoxy</application> through
1092 a package manager, the package will probably contain a platform-specific
1093 script or configuration file to start <application>Privoxy</application>
1098 <sect2 id="start-os2">
1101 During installation, <application>Privoxy</application> is configured to
1102 start automatically when the system restarts. You can start it manually by
1103 double-clicking on the <application>Privoxy</application> icon in the
1104 <application>Privoxy</application> folder.
1108 <sect2 id="start-macosx">
1109 <title>Mac OS X</title>
1111 The privoxy service will automatically start after a successful installation
1112 (and thereafter every time your computer starts up) however you will need to
1113 configure your web browser(s) to use it. To do so, configure them to use a
1114 proxy for HTTP and HTTPS at the address 127.0.0.1:8118.
1117 To prevent the privoxy service from automatically starting when your computer
1118 starts up, remove or rename the file <literal>/Library/LaunchDaemons/org.ijbswa.privoxy.plist</literal>
1119 (on OS X 10.5 and higher) or the folder named
1120 <literal>/Library/StartupItems/Privoxy</literal> (on OS X 10.4 'Tiger').
1123 To manually start or stop the privoxy service, use the scripts startPrivoxy.sh
1124 and stopPrivoxy.sh supplied in /Applications/Privoxy. They must be run from an
1125 administrator account, using sudo.
1133 See the section <link linkend="cmdoptions">Command line options</link> for
1137 must find a better place for this paragraph
1140 The included default configuration files should give a reasonable starting
1141 point. Most of the per site configuration is done in the
1142 <ulink url="actions-file.html"><quote>actions</quote></ulink> files. These are
1143 where various cookie actions are defined, ad and banner blocking, and other
1144 aspects of <application>Privoxy</application> configuration. There are several
1145 such files included, with varying levels of aggressiveness.
1149 You will probably want to keep an eye out for sites for which you may prefer
1150 persistent cookies, and add these to your actions configuration as needed. By
1151 default, most of these will be accepted only during the current browser
1152 session (aka <quote>session cookies</quote>), unless you add them to the
1153 configuration. If you want the browser to handle this instead, you will need
1154 to edit <filename>user.action</filename> (or through the web based interface)
1155 and disable this feature. If you use more than one browser, it would make
1156 more sense to let <application>Privoxy</application> handle this. In which
1157 case, the browser(s) should be set to accept all cookies.
1161 Another feature where you will probably want to define exceptions for trusted
1162 sites is the popup-killing (through <ulink
1163 url="actions-file.html#FILTER-POPUPS"><quote>+filter{popups}</quote></ulink>),
1164 because your favorite shopping, banking, or leisure site may need
1165 popups (explained below).
1169 <application>Privoxy</application> does not support all of the optional HTTP/1.1
1170 features yet. In the unlikely event that you experience inexplicable problems
1171 with browsers that use HTTP/1.1 per default
1172 (like <application>Mozilla</application> or recent versions of I.E.), you might
1173 try to force HTTP/1.0 compatibility. For Mozilla, look under <literal>Edit ->
1174 Preferences -> Debug -> Networking</literal>.
1175 Alternatively, set the <quote>+downgrade-http-version</quote> config option in
1176 <filename>default.action</filename> which will downgrade your browser's HTTP
1177 requests from HTTP/1.1 to HTTP/1.0 before processing them.
1181 After running <application>Privoxy</application> for a while, you can
1182 start to fine tune the configuration to suit your personal, or site,
1183 preferences and requirements. There are many, many aspects that can
1184 be customized. <quote>Actions</quote>
1185 can be adjusted by pointing your browser to
1186 <ulink url="http://config.privoxy.org/">http://config.privoxy.org/</ulink>
1187 (shortcut: <ulink url="http://p.p/">http://p.p/</ulink>),
1188 and then follow the link to <quote>View & Change the Current Configuration</quote>.
1189 (This is an internal page and does not require Internet access.)
1193 In fact, various aspects of <application>Privoxy</application>
1194 configuration can be viewed from this page, including
1195 current configuration parameters, source code version numbers,
1196 the browser's request headers, and <quote>actions</quote> that apply
1197 to a given URL. In addition to the actions file
1198 editor mentioned above, <application>Privoxy</application> can also
1199 be turned <quote>on</quote> and <quote>off</quote> (toggled) from this page.
1203 If you encounter problems, try loading the page without
1204 <application>Privoxy</application>. If that helps, enter the URL where
1205 you have the problems into <ulink url="http://p.p/show-url-info">the browser
1206 based rule tracing utility</ulink>. See which rules apply and why, and
1207 then try turning them off for that site one after the other, until the problem
1208 is gone. When you have found the culprit, you might want to turn the rest on
1213 If the above paragraph sounds gibberish to you, you might want to <link
1214 linkend="actions-file">read more about the actions concept</link>
1215 or even dive deep into the <link linkend="actionsanat">Appendix
1220 If you can't get rid of the problem at all, think you've found a bug in
1221 Privoxy, want to propose a new feature or smarter rules, please see the
1222 section <link linkend="contact"><quote>Contacting the
1223 Developers</quote></link> below.
1228 <!-- ~~~~~ New section ~~~~~ -->
1229 <sect2 id="cmdoptions">
1230 <title>Command Line Options</title>
1232 <application>Privoxy</application> may be invoked with the following
1233 command-line options:
1240 <emphasis>--config-test</emphasis>
1243 Exit after loading the configuration files before binding to
1244 the listen address. The exit code signals whether or not the
1245 configuration files have been successfully loaded.
1248 If the exit code is 1, at least one of the configuration files
1249 is invalid, if it is 0, all the configuration files have been
1250 successfully loaded (but may still contain errors that can
1251 currently only be detected at run time).
1254 This option doesn't affect the log setting, combination with
1255 <emphasis>--no-daemon</emphasis> is recommended if a configured
1256 log file shouldn't be used.
1261 <emphasis>--version</emphasis>
1264 Print version info and exit. Unix only.
1269 <emphasis>--help</emphasis>
1272 Print short usage info and exit. Unix only.
1277 <emphasis>--no-daemon</emphasis>
1280 Don't become a daemon, i.e. don't fork and become process group
1281 leader, and don't detach from controlling tty. Unix only.
1286 <emphasis>--pidfile FILE</emphasis>
1289 On startup, write the process ID to <emphasis>FILE</emphasis>. Delete the
1290 <emphasis>FILE</emphasis> on exit. Failure to create or delete the
1291 <emphasis>FILE</emphasis> is non-fatal. If no <emphasis>FILE</emphasis>
1292 option is given, no PID file will be used. Unix only.
1297 <emphasis>--user USER[.GROUP]</emphasis>
1300 After (optionally) writing the PID file, assume the user ID of
1301 <emphasis>USER</emphasis>, and if included the GID of GROUP. Exit if the
1302 privileges are not sufficient to do so. Unix only.
1307 <emphasis>--chroot</emphasis>
1310 Before changing to the user ID given in the <emphasis>--user</emphasis> option,
1311 chroot to that user's home directory, i.e. make the kernel pretend to the &my-app;
1312 process that the directory tree starts there. If set up carefully, this can limit
1313 the impact of possible vulnerabilities in &my-app; to the files contained in that hierarchy.
1319 <emphasis>--pre-chroot-nslookup hostname</emphasis>
1322 Specifies a hostname (for example www.privoxy.org) to look up before doing a chroot.
1323 On some systems, initializing the resolver library involves reading config files from
1324 /etc and/or loading additional shared libraries from /lib.
1325 On these systems, doing a hostname lookup before the chroot reduces
1326 the number of files that must be copied into the chroot tree.
1329 For fastest startup speed, a good value is a hostname that is not in /etc/hosts but that
1330 your local name server (listed in /etc/resolv.conf) can resolve without recursion
1331 (that is, without having to ask any other name servers). The hostname need not exist,
1332 but if it doesn't, an error message (which can be ignored) will be output.
1338 <emphasis>configfile</emphasis>
1341 If no <emphasis>configfile</emphasis> is included on the command line,
1342 <application>Privoxy</application> will look for a file named
1343 <quote>config</quote> in the current directory (except on Win32
1344 where it will look for <quote>config.txt</quote> instead). Specify
1345 full path to avoid confusion. If no config file is found,
1346 <application>Privoxy</application> will fail to start.
1353 On <application>MS Windows</application> only there are two additional
1354 command-line options to allow <application>Privoxy</application> to install and
1355 run as a <emphasis>service</emphasis>. See the
1356 <link linkend="installation-pack-win">Window Installation section</link>
1364 <!-- ~ End section ~ -->
1367 <!-- ~~~~~ New section ~~~~~ -->
1368 <sect1 id="configuration"><title>Privoxy Configuration</title>
1370 All <application>Privoxy</application> configuration is stored
1371 in text files. These files can be edited with a text editor.
1372 Many important aspects of <application>Privoxy</application> can
1373 also be controlled easily with a web browser.
1377 <!-- ~~~~~ New section ~~~~~ -->
1379 <sect2 id="control-with-webbrowser">
1380 <title>Controlling Privoxy with Your Web Browser</title>
1382 <application>Privoxy</application>'s user interface can be reached through the special
1383 URL <ulink url="http://config.privoxy.org/">http://config.privoxy.org/</ulink>
1384 (shortcut: <ulink url="http://p.p/">http://p.p/</ulink>),
1385 which is a built-in page and works without Internet access.
1386 You will see the following section:
1389 <!-- Needs to be put in a table and colorized -->
1392 <bridgehead renderas="sect2"> Privoxy Menu</bridgehead>
1396 ▪ <ulink url="http://config.privoxy.org/show-status">View & change the current configuration</ulink>
1399 ▪ <ulink url="http://config.privoxy.org/show-version">View the source code version numbers</ulink>
1402 ▪ <ulink url="http://config.privoxy.org/show-request">View the request headers.</ulink>
1405 ▪ <ulink url="http://config.privoxy.org/show-url-info">Look up which actions apply to a URL and why</ulink>
1408 ▪ <ulink url="http://config.privoxy.org/toggle">Toggle Privoxy on or off</ulink>
1411 ▪ <ulink
1412 url="https://www.privoxy.org/&p-version;/user-manual/">Documentation</ulink>
1420 This should be self-explanatory. Note the first item leads to an editor for the
1421 <link linkend="actions-file">actions files</link>, which is where the ad, banner,
1422 cookie, and URL blocking magic is configured as well as other advanced features of
1423 <application>Privoxy</application>. This is an easy way to adjust various
1424 aspects of <application>Privoxy</application> configuration. The actions
1425 file, and other configuration files, are explained in detail below.
1429 <quote>Toggle Privoxy On or Off</quote> is handy for sites that might
1430 have problems with your current actions and filters. You can in fact use
1431 it as a test to see whether it is <application>Privoxy</application>
1432 causing the problem or not. <application>Privoxy</application> continues
1433 to run as a proxy in this case, but all manipulation is disabled, i.e.
1434 <application>Privoxy</application> acts like a normal forwarding proxy.
1438 Note that several of the features described above are disabled by default
1439 in <application>Privoxy</application> 3.0.7 beta and later.
1441 <ulink url="config.html">configuration file</ulink> to learn why
1442 and in which cases it's safe to enable them again.
1447 <!-- ~ End section ~ -->
1452 <!-- ~~~~~ New section ~~~~~ -->
1454 <sect2 id="confoverview">
1455 <title>Configuration Files Overview</title>
1457 For Unix, *BSD and Linux, all configuration files are located in
1458 <filename>/etc/privoxy/</filename> by default. For MS Windows, OS/2, and
1459 AmigaOS these are all in the same directory as the
1460 <application>Privoxy</application> executable. <![%p-not-stable;[ The name
1461 and number of configuration files has changed from previous versions, and is
1462 subject to change as development progresses.]]>
1466 The installed defaults provide a reasonable starting point, though
1467 some settings may be aggressive by some standards. For the time being, the
1468 principle configuration files are:
1475 The <link linkend="config">main configuration file</link> is named <filename>config</filename>
1476 on Linux, Unix, BSD, OS/2, and AmigaOS and <filename>config.txt</filename>
1477 on Windows. This is a required file.
1483 <filename>match-all.action</filename> is used to define which <quote>actions</quote>
1484 relating to banner-blocking, images, pop-ups, content modification, cookie handling
1485 etc should be applied by default. It should be the first actions file loaded.
1488 <filename>default.action</filename> defines many exceptions (both positive and negative)
1489 from the default set of actions that's configured in <filename>match-all.action</filename>.
1490 It should be the second actions file loaded and shouldn't be edited by the user.
1493 Multiple actions files may be defined in <filename>config</filename>. These
1494 are processed in the order they are defined. Local customizations and locally
1495 preferred exceptions to the default policies as defined in
1496 <filename>match-all.action</filename> (which you will most probably want
1497 to define sooner or later) are best applied in <filename>user.action</filename>,
1498 where you can preserve them across upgrades. The file isn't installed by all
1499 installers, but you can easily create it yourself with a text editor.
1502 There is also a web based editor that can be accessed from
1504 url="http://config.privoxy.org/show-status">http://config.privoxy.org/show-status</ulink>
1506 url="http://p.p/show-status">http://p.p/show-status</ulink>) for the
1507 various actions files.
1513 <quote>Filter files</quote> (the <link linkend="filter-file">filter
1514 file</link>) can be used to re-write the raw page content, including
1515 viewable text as well as embedded HTML and JavaScript, and whatever else
1516 lurks on any given web page. The filtering jobs are only pre-defined here;
1517 whether to apply them or not is up to the actions files.
1518 <filename>default.filter</filename> includes various filters made
1519 available for use by the developers. Some are much more intrusive than
1520 others, and all should be used with caution. You may define additional
1521 filter files in <filename>config</filename> as you can with
1522 actions files. We suggest <filename>user.filter</filename> for any
1523 locally defined filters or customizations.
1530 The syntax of the configuration and filter files may change between different
1531 Privoxy versions, unfortunately some enhancements cost backwards compatibility.
1532 <!-- Add link to documentation-->
1536 All files use the <quote><literal>#</literal></quote> character to denote a
1537 comment (the rest of the line will be ignored) and understand line continuation
1538 through placing a backslash ("<literal>\</literal>") as the very last character
1539 in a line. If the <literal>#</literal> is preceded by a backslash, it looses
1540 its special function. Placing a <literal>#</literal> in front of an otherwise
1541 valid configuration line to prevent it from being interpreted is called "commenting
1542 out" that line. Blank lines are ignored.
1546 The actions files and filter files
1547 can use Perl style <link linkend="regex">regular expressions</link> for
1548 maximum flexibility.
1552 After making any changes, there is no need to restart
1553 <application>Privoxy</application> in order for the changes to take
1554 effect. <application>Privoxy</application> detects such changes
1555 automatically. Note, however, that it may take one or two additional
1556 requests for the change to take effect. When changing the listening address
1557 of <application>Privoxy</application>, these <quote>wake up</quote> requests
1558 must obviously be sent to the <emphasis>old</emphasis> listening address.
1563 While under development, the configuration content is subject to change.
1564 The below documentation may not be accurate by the time you read this.
1565 Also, what constitutes a <quote>default</quote> setting, may change, so
1566 please check all your configuration files on important issues.
1572 <!-- ~ End section ~ -->
1575 <!-- ~~~~~~~~ New section Header ~~~~~~~~~ -->
1577 <!-- **************************************************** -->
1578 <!-- Include config.sgml here -->
1579 <!-- This is where the entire config file is detailed. -->
1581 <!-- end include -->
1584 <!-- ~ End section ~ -->
1588 <!-- ~~~~~~~~ New section Header ~~~~~~~~~ -->
1590 <sect1 id="actions-file"><title>Actions Files</title>
1594 XXX: similar descriptions are in the Configuration Files sections.
1595 We should only describe them at one place.
1598 The actions files are used to define what <emphasis>actions</emphasis>
1599 <application>Privoxy</application> takes for which URLs, and thus determines
1600 how ad images, cookies and various other aspects of HTTP content and
1601 transactions are handled, and on which sites (or even parts thereof).
1602 There are a number of such actions, with a wide range of functionality.
1603 Each action does something a little different.
1604 These actions give us a veritable arsenal of tools with which to exert
1605 our control, preferences and independence. Actions can be combined so that
1606 their effects are aggregated when applied against a given set of URLs.
1610 are three action files included with <application>Privoxy</application> with
1616 <filename>match-all.action</filename> - is used to define which
1617 <quote>actions</quote> relating to banner-blocking, images, pop-ups,
1618 content modification, cookie handling etc should be applied by default.
1619 It should be the first actions file loaded
1624 <filename>default.action</filename> - defines many exceptions (both
1625 positive and negative) from the default set of actions that's configured
1626 in <filename>match-all.action</filename>. It is a set of rules that should
1627 work reasonably well as-is for most users. This file is only supposed to
1628 be edited by the developers. It should be the second actions file loaded.
1633 <filename>user.action</filename> - is intended to be for local site
1634 preferences and exceptions. As an example, if your ISP or your bank
1635 has specific requirements, and need special handling, this kind of
1636 thing should go here. This file will not be upgraded.
1641 <guibutton>Edit</guibutton> <guibutton>Set to Cautious</guibutton> <guibutton>Set to Medium</guibutton> <guibutton>Set to Advanced</guibutton>
1644 These have increasing levels of aggressiveness <emphasis>and have no
1645 influence on your browsing unless you select them explicitly in the
1646 editor</emphasis>. A default installation should be pre-set to
1647 <literal>Cautious</literal>. New users should try this for a while before
1648 adjusting the settings to more aggressive levels. The more aggressive
1649 the settings, then the more likelihood there is of problems such as sites
1650 not working as they should.
1653 The <guibutton>Edit</guibutton> button allows you to turn each
1654 action on/off individually for fine-tuning. The <guibutton>Cautious</guibutton>
1655 button changes the actions list to low/safe settings which will activate
1656 ad blocking and a minimal set of &my-app;'s features, and subsequently
1657 there will be less of a chance for accidental problems. The
1658 <guibutton>Medium</guibutton> button sets the list to a medium level of
1659 other features and a low level set of privacy features. The
1660 <guibutton>Advanced</guibutton> button sets the list to a high level of
1661 ad blocking and medium level of privacy. See the chart below. The latter
1662 three buttons over-ride any changes via with the
1663 <guibutton>Edit</guibutton> button. More fine-tuning can be done in the
1664 lower sections of this internal page.
1667 While the actions file editor allows to enable these settings in all
1668 actions files, they are only supposed to be enabled in the first one
1669 to make sure you don't unintentionally overrule earlier rules.
1672 The default profiles, and their associated actions, as pre-defined in
1673 <filename>default.action</filename> are:
1675 <table frame=all><title>Default Configurations</title>
1676 <tgroup cols=4 align=left colsep=1 rowsep=1>
1677 <colspec colname=c1>
1678 <colspec colname=c2>
1679 <colspec colname=c3>
1680 <colspec colname=c4>
1683 <entry>Feature</entry>
1684 <entry>Cautious</entry>
1685 <entry>Medium</entry>
1686 <entry>Advanced</entry>
1691 <!-- <entry>f1</entry> -->
1692 <!-- <entry>f2</entry> -->
1693 <!-- <entry>f3</entry> -->
1694 <!-- <entry>f4</entry> -->
1700 <entry>Ad-blocking Aggressiveness</entry>
1701 <entry>medium</entry>
1707 <entry>Ad-filtering by size</entry>
1714 <entry>Ad-filtering by link</entry>
1720 <entry>Pop-up killing</entry>
1721 <entry>blocks only</entry>
1722 <entry>blocks only</entry>
1723 <entry>blocks only</entry>
1727 <entry>Privacy Features</entry>
1729 <entry>medium</entry>
1730 <entry>medium/high</entry>
1734 <entry>Cookie handling</entry>
1736 <entry>session-only</entry>
1741 <entry>Referer forging</entry>
1748 <entry>GIF de-animation</entry>
1755 <entry>Fast redirects</entry>
1762 <entry>HTML taming</entry>
1769 <entry>JavaScript taming</entry>
1776 <entry>Web-bug killing</entry>
1783 <entry>Image tag reordering</entry>
1797 The list of actions files to be used are defined in the main configuration
1798 file, and are processed in the order they are defined (e.g.
1799 <filename>default.action</filename> is typically processed before
1800 <filename>user.action</filename>). The content of these can all be viewed and
1802 url="http://config.privoxy.org/show-status">http://config.privoxy.org/show-status</ulink>.
1803 The over-riding principle when applying actions, is that the last action that
1804 matches a given URL wins. The broadest, most general rules go first
1805 (defined in <filename>default.action</filename>),
1806 followed by any exceptions (typically also in
1807 <filename>default.action</filename>), which are then followed lastly by any
1808 local preferences (typically in <emphasis>user</emphasis><filename>.action</filename>).
1809 Generally, <filename>user.action</filename> has the last word.
1813 An actions file typically has multiple sections. If you want to use
1814 <quote>aliases</quote> in an actions file, you have to place the (optional)
1815 <link linkend="aliases">alias section</link> at the top of that file.
1816 Then comes the default set of rules which will apply universally to all
1817 sites and pages (be <emphasis>very careful</emphasis> with using such a
1818 universal set in <filename>user.action</filename> or any other actions file after
1819 <filename>default.action</filename>, because it will override the result
1820 from consulting any previous file). And then below that,
1821 exceptions to the defined universal policies. You can regard
1822 <filename>user.action</filename> as an appendix to <filename>default.action</filename>,
1823 with the advantage that it is a separate file, which makes preserving your
1824 personal settings across <application>Privoxy</application> upgrades easier.
1828 Actions can be used to block anything you want, including ads, banners, or
1829 just some obnoxious URL whose content you would rather not see. Cookies can be accepted
1830 or rejected, or accepted only during the current browser session (i.e. not
1831 written to disk), content can be modified, some JavaScripts tamed, user-tracking
1832 fooled, and much more. See below for a <link linkend="actions">complete list
1836 <!-- ~~~~~ New section ~~~~~ -->
1837 <sect2 id="right-mix">
1838 <title>Finding the Right Mix</title>
1840 Note that some <link linkend="actions">actions</link>, like cookie suppression
1841 or script disabling, may render some sites unusable that rely on these
1842 techniques to work properly. Finding the right mix of actions is not always easy and
1843 certainly a matter of personal taste. And, things can always change, requiring
1844 refinements in the configuration. In general, it can be said that the more
1845 <quote>aggressive</quote> your default settings (in the top section of the
1846 actions file) are, the more exceptions for <quote>trusted</quote> sites you
1847 will have to make later. If, for example, you want to crunch all cookies per
1848 default, you'll have to make exceptions from that rule for sites that you
1849 regularly use and that require cookies for actually useful purposes, like maybe
1850 your bank, favorite shop, or newspaper.
1854 We have tried to provide you with reasonable rules to start from in the
1855 distribution actions files. But there is no general rule of thumb on these
1856 things. There just are too many variables, and sites are constantly changing.
1857 Sooner or later you will want to change the rules (and read this chapter again :).
1861 <!-- ~~~~~ New section ~~~~~ -->
1862 <sect2 id="how-to-edit">
1863 <title>How to Edit</title>
1865 The easiest way to edit the actions files is with a browser by
1866 using our browser-based editor, which can be reached from <ulink
1867 url="http://config.privoxy.org/show-status">http://config.privoxy.org/show-status</ulink>.
1868 Note: the config file option <link
1869 linkend="enable-edit-actions">enable-edit-actions</link> must be enabled for
1870 this to work. The editor allows both fine-grained control over every single
1871 feature on a per-URL basis, and easy choosing from wholesale sets of defaults
1872 like <quote>Cautious</quote>, <quote>Medium</quote> or
1873 <quote>Advanced</quote>. Warning: the <quote>Advanced</quote> setting is more
1874 aggressive, and will be more likely to cause problems for some sites.
1875 Experienced users only!
1879 If you prefer plain text editing to GUIs, you can of course also directly edit the
1880 the actions files with your favorite text editor. Look at
1881 <filename>default.action</filename> which is richly commented with many
1887 <sect2 id="actions-apply">
1888 <title>How Actions are Applied to Requests</title>
1890 Actions files are divided into sections. There are special sections,
1891 like the <quote><link linkend="aliases">alias</link></quote> sections which will
1892 be discussed later. For now let's concentrate on regular sections: They have a
1893 heading line (often split up to multiple lines for readability) which consist
1894 of a list of actions, separated by whitespace and enclosed in curly braces.
1895 Below that, there is a list of URL and tag patterns, each on a separate line.
1899 To determine which actions apply to a request, the URL of the request is
1900 compared to all URL patterns in each <quote>action file</quote>.
1901 Every time it matches, the list of applicable actions for the request is
1902 incrementally updated, using the heading of the section in which the
1903 pattern is located. The same is done again for tags and tag patterns later on.
1907 If multiple applying sections set the same action differently,
1908 the last match wins. If not, the effects are aggregated.
1909 E.g. a URL might match a regular section with a heading line of <literal>{
1910 +<link linkend="handle-as-image">handle-as-image</link> }</literal>,
1911 then later another one with just <literal>{
1912 +<link linkend="block">block</link> }</literal>, resulting
1913 in <emphasis>both</emphasis> actions to apply. And there may well be
1914 cases where you will want to combine actions together. Such a section then
1919 { +<literal>handle-as-image</literal> +<literal>block{Banner ads.}</literal> }
1920 # Block these as if they were images. Send no block page.
1922 media.example.com/.*banners
1923 .example.com/images/ads/</screen>
1926 You can trace this process for URL patterns and any given URL by visiting <ulink
1927 url="http://config.privoxy.org/show-url-info">http://config.privoxy.org/show-url-info</ulink>.
1931 Examples and more detail on this is provided in the Appendix, <link linkend="ACTIONSANAT">
1932 Troubleshooting: Anatomy of an Action</link> section.
1936 <!-- ~~~~~ New section ~~~~~ -->
1937 <sect2 id="af-patterns">
1938 <title>Patterns</title>
1940 As mentioned, <application>Privoxy</application> uses <quote>patterns</quote>
1941 to determine what <emphasis>actions</emphasis> might apply to which sites and
1942 pages your browser attempts to access. These <quote>patterns</quote> use wild
1943 card type <emphasis>pattern</emphasis> matching to achieve a high degree of
1944 flexibility. This allows one expression to be expanded and potentially match
1945 against many similar patterns.
1949 Generally, an URL pattern has the form
1950 <literal><host><port>/<path></literal>, where the
1951 <literal><host></literal>, the <literal><port></literal>
1952 and the <literal><path></literal> are optional. (This is why the special
1953 <literal>/</literal> pattern matches all URLs). Note that the protocol
1954 portion of the URL pattern (e.g. <literal>http://</literal>) should
1955 <emphasis>not</emphasis> be included in the pattern. This is assumed already!
1958 The pattern matching syntax is different for the host and path parts of
1959 the URL. The host part uses a simple globbing type matching technique,
1960 while the path part uses more flexible
1961 <ulink url="http://en.wikipedia.org/wiki/Regular_expressions"><quote>Regular
1962 Expressions</quote></ulink> (POSIX 1003.2).
1965 The port part of a pattern is a decimal port number preceded by a colon
1966 (<literal>:</literal>). If the host part contains a numerical IPv6 address,
1967 it has to be put into angle brackets
1968 (<literal><</literal>, <literal>></literal>).
1973 <term><literal>www.example.com/</literal></term>
1976 is a host-only pattern and will match any request to <literal>www.example.com</literal>,
1977 regardless of which document on that server is requested. So ALL pages in
1978 this domain would be covered by the scope of this action. Note that a
1979 simple <literal>example.com</literal> is different and would NOT match.
1984 <term><literal>www.example.com</literal></term>
1987 means exactly the same. For host-only patterns, the trailing <literal>/</literal> may
1993 <term><literal>www.example.com/index.html</literal></term>
1996 matches all the documents on <literal>www.example.com</literal>
1997 whose name starts with <literal>/index.html</literal>.
2002 <term><literal>www.example.com/index.html$</literal></term>
2005 matches only the single document <literal>/index.html</literal>
2006 on <literal>www.example.com</literal>.
2011 <term><literal>/index.html$</literal></term>
2014 matches the document <literal>/index.html</literal>, regardless of the domain,
2015 i.e. on <emphasis>any</emphasis> web server anywhere.
2020 <term><literal>/</literal></term>
2023 Matches any URL because there's no requirement for either the
2024 domain or the path to match anything.
2029 <term><literal>:8000/</literal></term>
2032 Matches any URL pointing to TCP port 8000.
2037 <term><literal>10.0.0.1/</literal></term>
2040 Matches any URL with the host address <literal>10.0.0.1</literal>.
2041 (Note that the real URL uses plain brackets, not angle brackets.)
2046 <term><literal><2001:db8::1>/</literal></term>
2049 Matches any URL with the host address <literal>2001:db8::1</literal>.
2050 (Note that the real URL uses plain brackets, not angle brackets.)
2055 <term><literal>index.html</literal></term>
2058 matches nothing, since it would be interpreted as a domain name and
2059 there is no top-level domain called <literal>.html</literal>. So its
2067 <!-- ~~~~~ New section ~~~~~ -->
2068 <sect3 id="host-pattern"><title>The Host Pattern</title>
2071 The matching of the host part offers some flexible options: if the
2072 host pattern starts or ends with a dot, it becomes unanchored at that end.
2073 The host pattern is often referred to as domain pattern as it is usually
2074 used to match domain names and not IP addresses.
2080 <term><literal>.example.com</literal></term>
2083 matches any domain with first-level domain <literal>com</literal>
2084 and second-level domain <literal>example</literal>.
2085 For example <literal>www.example.com</literal>,
2086 <literal>example.com</literal> and <literal>foo.bar.baz.example.com</literal>.
2087 Note that it wouldn't match if the second-level domain was <literal>another-example</literal>.
2092 <term><literal>www.</literal></term>
2095 matches any domain that <emphasis>STARTS</emphasis> with
2096 <literal>www.</literal> (It also matches the domain
2097 <literal>www</literal> but most of the time that doesn't matter.)
2102 <term><literal>.example.</literal></term>
2105 matches any domain that <emphasis>CONTAINS</emphasis> <literal>.example.</literal>.
2106 And, by the way, also included would be any files or documents that exist
2107 within that domain since no path limitations are specified. (Correctly
2108 speaking: It matches any FQDN that contains <literal>example</literal> as
2109 a domain.) This might be <literal>www.example.com</literal>,
2110 <literal>news.example.de</literal>, or
2111 <literal>www.example.net/cgi/testing.pl</literal> for instance. All these
2119 Additionally, there are wild-cards that you can use in the domain names
2120 themselves. These work similarly to shell globbing type wild-cards:
2121 <quote>*</quote> represents zero or more arbitrary characters (this is
2123 <ulink url="http://en.wikipedia.org/wiki/Regular_expressions"><quote>Regular
2124 Expression</quote></ulink> based syntax of <quote>.*</quote>),
2125 <quote>?</quote> represents any single character (this is equivalent to the
2126 regular expression syntax of a simple <quote>.</quote>), and you can define
2127 <quote>character classes</quote> in square brackets which is similar to
2128 the same regular expression technique. All of this can be freely mixed:
2133 <term><literal>ad*.example.com</literal></term>
2136 matches <quote>adserver.example.com</quote>,
2137 <quote>ads.example.com</quote>, etc but not <quote>sfads.example.com</quote>
2142 <term><literal>*ad*.example.com</literal></term>
2145 matches all of the above, and then some.
2150 <term><literal>.?pix.com</literal></term>
2153 matches <literal>www.ipix.com</literal>,
2154 <literal>pictures.epix.com</literal>, <literal>a.b.c.d.e.upix.com</literal> etc.
2159 <term><literal>www[1-9a-ez].example.c*</literal></term>
2162 matches <literal>www1.example.com</literal>,
2163 <literal>www4.example.cc</literal>, <literal>wwwd.example.cy</literal>,
2164 <literal>wwwz.example.com</literal> etc., but <emphasis>not</emphasis>
2165 <literal>wwww.example.com</literal>.
2172 While flexible, this is not the sophistication of full regular expression based syntax.
2177 <!-- ~ End section ~ -->
2180 <!-- ~~~~~ New section ~~~~~ -->
2181 <sect3 id="path-pattern"><title>The Path Pattern</title>
2184 <application>Privoxy</application> uses <quote>modern</quote> POSIX 1003.2
2185 <ulink url="http://en.wikipedia.org/wiki/Regular_expressions"><quote>Regular
2186 Expressions</quote></ulink> for matching the path portion (after the slash),
2187 and is thus more flexible.
2191 There is an <link linkend="regex">Appendix</link> with a brief quick-start into regular
2192 expressions, you also might want to have a look at your operating system's documentation
2193 on regular expressions (try <literal>man re_format</literal>).
2197 Note that the path pattern is automatically left-anchored at the <quote>/</quote>,
2198 i.e. it matches as if it would start with a <quote>^</quote> (regular expression speak
2199 for the beginning of a line).
2203 Please also note that matching in the path is <emphasis>CASE INSENSITIVE</emphasis>
2204 by default, but you can switch to case sensitive at any point in the pattern by using the
2205 <quote>(?-i)</quote> switch: <literal>www.example.com/(?-i)PaTtErN.*</literal> will match
2206 only documents whose path starts with <literal>PaTtErN</literal> in
2207 <emphasis>exactly</emphasis> this capitalization.
2212 <term><literal>.example.com/.*</literal></term>
2215 Is equivalent to just <quote>.example.com</quote>, since any documents
2216 within that domain are matched with or without the <quote>.*</quote>
2217 regular expression. This is redundant
2222 <term><literal>.example.com/.*/index.html$</literal></term>
2225 Will match any page in the domain of <quote>example.com</quote> that is
2226 named <quote>index.html</quote>, and that is part of some path. For
2227 example, it matches <quote>www.example.com/testing/index.html</quote> but
2228 NOT <quote>www.example.com/index.html</quote> because the regular
2229 expression called for at least two <quote>/'s</quote>, thus the path
2230 requirement. It also would match
2231 <quote>www.example.com/testing/index_html</quote>, because of the
2232 special meta-character <quote>.</quote>.
2237 <term><literal>.example.com/(.*/)?index\.html$</literal></term>
2240 This regular expression is conditional so it will match any page
2241 named <quote>index.html</quote> regardless of path which in this case can
2242 have one or more <quote>/'s</quote>. And this one must contain exactly
2243 <quote>.html</quote> (and end with that!).
2248 <term><literal>.example.com/(.*/)(ads|banners?|junk)</literal></term>
2251 This regular expression will match any path of <quote>example.com</quote>
2252 that contains any of the words <quote>ads</quote>, <quote>banner</quote>,
2253 <quote>banners</quote> (because of the <quote>?</quote>) or <quote>junk</quote>.
2254 The path does not have to end in these words, just contain them.
2255 The path has to contain at least two slashes (including the one at the beginning).
2260 <term><literal>.example.com/(.*/)(ads|banners?|junk)/.*\.(jpe?g|gif|png)$</literal></term>
2263 This is very much the same as above, except now it must end in either
2264 <quote>.jpg</quote>, <quote>.jpeg</quote>, <quote>.gif</quote> or <quote>.png</quote>. So this
2265 one is limited to common image formats.
2272 There are many, many good examples to be found in <filename>default.action</filename>,
2273 and more tutorials below in <link linkend="regex">Appendix on regular expressions</link>.
2278 <!-- ~ End section ~ -->
2281 <!-- ~~~~~ New section ~~~~~ -->
2282 <sect3 id="tag-pattern"><title>The Request Tag Pattern</title>
2285 Request tag patterns are used to change the applying actions based on the
2286 request's tags. Tags can be created based on HTTP headers with either
2287 the <link linkend="CLIENT-HEADER-TAGGER">client-header-tagger</link>
2288 or the <link linkend="SERVER-HEADER-TAGGER">server-header-tagger</link> action.
2292 Request tag patterns have to start with <quote>TAG:</quote>, so &my-app;
2293 can tell them apart from other patterns. Everything after the colon
2294 including white space, is interpreted as a regular expression with
2295 path pattern syntax, except that tag patterns aren't left-anchored
2296 automatically (&my-app; doesn't silently add a <quote>^</quote>,
2297 you have to do it yourself if you need it).
2301 To match all requests that are tagged with <quote>foo</quote>
2302 your pattern line should be <quote>TAG:^foo$</quote>,
2303 <quote>TAG:foo</quote> would work as well, but it would also
2304 match requests whose tags contain <quote>foo</quote> somewhere.
2305 <quote>TAG: foo</quote> wouldn't work as it requires white space.
2309 Sections can contain URL and request tag patterns at the same time,
2310 but request tag patterns are checked after the URL patterns and thus
2311 always overrule them, even if they are located before the URL patterns.
2315 Once a new request tag is added, Privoxy checks right away if it's matched by one
2316 of the request tag patterns and updates the action settings accordingly. As a result
2317 request tags can be used to activate other tagger actions, as long as these other
2318 taggers look for headers that haven't already be parsed.
2322 For example you could tag client requests which use the
2323 <literal>POST</literal> method,
2324 then use this tag to activate another tagger that adds a tag if cookies
2325 are sent, and then use a block action based on the cookie tag. This allows
2326 the outcome of one action, to be input into a subsequent action. However if
2327 you'd reverse the position of the described taggers, and activated the
2328 method tagger based on the cookie tagger, no method tags would be created.
2329 The method tagger would look for the request line, but at the time
2330 the cookie tag is created, the request line has already been parsed.
2334 While this is a limitation you should be aware of, this kind of
2335 indirection is seldom needed anyway and even the example doesn't
2336 make too much sense.
2341 <!-- ~~~~~ New section ~~~~~ -->
2342 <sect3 id="negative-tag-patterns"><title>The Negative Request Tag Patterns</title>
2345 To match requests that do not have a certain request tag, specify a negative tag pattern
2346 by prefixing the tag pattern line with either <quote>NO-REQUEST-TAG:</quote>
2347 or <quote>NO-RESPONSE-TAG:</quote> instead of <quote>TAG:</quote>.
2351 Negative request tag patterns created with <quote>NO-REQUEST-TAG:</quote> are checked
2352 after all client headers are scanned, the ones created with <quote>NO-RESPONSE-TAG:</quote>
2353 are checked after all server headers are scanned. In both cases all the created
2354 tags are considered.
2358 <!-- ~~~~~ New section ~~~~~ -->
2359 <sect3 id="client-tag-pattern"><title>The Client Tag Pattern</title>
2361 <!-- XXX: This section contains duplicates content from the
2362 client-specific-tag documentation. -->
2366 This is an experimental feature. The syntax is likely to change in future versions.
2371 Client tag patterns are not set based on HTTP headers but based on
2372 the client's IP address. Users can enable them themselves, but the
2373 Privoxy admin controls which tags are available and what their effect
2378 After a client-specific tag has been defined with the
2379 <link linkend="client-specific-tag">client-specific-tag</link>,
2380 directive, action sections can be activated based on the tag by using a
2381 CLIENT-TAG pattern. The CLIENT-TAG pattern is evaluated at the same priority
2382 as URL patterns, as a result the last matching pattern wins. Tags that
2383 are created based on client or server headers are evaluated later on
2384 and can overrule CLIENT-TAG and URL patterns!
2387 The tag is set for all requests that come from clients that requested
2388 it to be set. Note that "clients" are differentiated by IP address,
2389 if the IP address changes the tag has to be requested again.
2392 Clients can request tags to be set by using the CGI interface <ulink
2393 url="http://config.privoxy.org/client-tags">http://config.privoxy.org/client-tags</ulink>.
2401 # If the admin defined the client-specific-tag circumvent-blocks,
2402 # and the request comes from a client that previously requested
2403 # the tag to be set, overrule all previous +block actions that
2404 # are enabled based on URL to CLIENT-TAG patterns.
2406 CLIENT-TAG:^circumvent-blocks$
2408 # This section is not overruled because it's located after
2410 {+block{Nobody is supposed to request this.}}
2411 example.org/blocked-example-page</screen>
2417 <!-- ~ End section ~ -->
2420 <!-- ~~~~~ New section ~~~~~ -->
2422 <sect2 id="actions">
2423 <title>Actions</title>
2425 All actions are disabled by default, until they are explicitly enabled
2426 somewhere in an actions file. Actions are turned on if preceded with a
2427 <quote>+</quote>, and turned off if preceded with a <quote>-</quote>. So a
2428 <literal>+action</literal> means <quote>do that action</quote>, e.g.
2429 <literal>+block</literal> means <quote>please block URLs that match the
2430 following patterns</quote>, and <literal>-block</literal> means <quote>don't
2431 block URLs that match the following patterns, even if <literal>+block</literal>
2432 previously applied.</quote>
2436 Again, actions are invoked by placing them on a line, enclosed in curly braces and
2437 separated by whitespace, like in
2438 <literal>{+some-action -some-other-action{some-parameter}}</literal>,
2439 followed by a list of URL patterns, one per line, to which they apply.
2440 Together, the actions line and the following pattern lines make up a section
2441 of the actions file.
2445 Actions fall into three categories:
2451 Boolean, i.e the action can only be <quote>enabled</quote> or
2452 <quote>disabled</quote>. Syntax:
2455 +<replaceable class="function">name</replaceable> # enable action <replaceable class="parameter">name</replaceable>
2456 -<replaceable class="function">name</replaceable> # disable action <replaceable class="parameter">name</replaceable></screen>
2458 Example: <literal>+handle-as-image</literal>
2465 Parameterized, where some value is required in order to enable this type of action.
2469 +<replaceable class="function">name</replaceable>{<replaceable class="parameter">param</replaceable>} # enable action and set parameter to <replaceable class="parameter">param</replaceable>,
2470 # overwriting parameter from previous match if necessary
2471 -<replaceable class="function">name</replaceable> # disable action. The parameter can be omitted</screen>
2473 Note that if the URL matches multiple positive forms of a parameterized action,
2474 the last match wins, i.e. the params from earlier matches are simply ignored.
2477 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>
2483 Multi-value. These look exactly like parameterized actions,
2484 but they behave differently: If the action applies multiple times to the
2485 same URL, but with different parameters, <emphasis>all</emphasis> the parameters
2486 from <emphasis>all</emphasis> matches are remembered. This is used for actions
2487 that can be executed for the same request repeatedly, like adding multiple
2488 headers, or filtering through multiple filters. Syntax:
2491 +<replaceable class="function">name</replaceable>{<replaceable class="parameter">param</replaceable>} # enable action and add <replaceable class="parameter">param</replaceable> to the list of parameters
2492 -<replaceable class="function">name</replaceable>{<replaceable class="parameter">param</replaceable>} # remove the parameter <replaceable class="parameter">param</replaceable> from the list of parameters
2493 # If it was the last one left, disable the action.
2494 <replaceable class="parameter">-name</replaceable> # disable this action completely and remove all parameters from the list</screen>
2496 Examples: <literal>+add-header{X-Fun-Header: Some text}</literal> and
2497 <literal>+filter{html-annoyances}</literal>
2504 If nothing is specified in any actions file, no <quote>actions</quote> are
2505 taken. So in this case <application>Privoxy</application> would just be a
2506 normal, non-blocking, non-filtering proxy. You must specifically enable the
2507 privacy and blocking features you need (although the provided default actions
2508 files will give a good starting point).
2512 Later defined action sections always over-ride earlier ones of the same type.
2513 So exceptions to any rules you make, should come in the latter part of the file (or
2514 in a file that is processed later when using multiple actions files such
2515 as <filename>user.action</filename>). For multi-valued actions, the actions
2516 are applied in the order they are specified. Actions files are processed in
2517 the order they are defined in <filename>config</filename> (the default
2518 installation has three actions files). It also quite possible for any given
2519 URL to match more than one <quote>pattern</quote> (because of wildcards and
2520 regular expressions), and thus to trigger more than one set of actions! Last
2524 <!-- start actions listing -->
2526 The list of valid <application>Privoxy</application> actions are:
2530 <!-- ********************************************************** -->
2531 <!-- Please note the below defined actions use id's that are -->
2532 <!-- probably linked from other places, so please don't change. -->
2534 <!-- ********************************************************** -->
2537 <!-- ~~~~~ New section ~~~~~ -->
2539 <sect3 renderas="sect4" id="add-header">
2540 <title>add-header</title>
2544 <term>Typical use:</term>
2546 <para>Confuse log analysis, custom applications</para>
2551 <term>Effect:</term>
2554 Sends a user defined HTTP header to the web server.
2561 <!-- boolean, parameterized, Multi-value -->
2563 <para>Multi-value.</para>
2568 <term>Parameter:</term>
2571 Any string value is possible. Validity of the defined HTTP headers is not checked.
2572 It is recommended that you use the <quote><literal>X-</literal></quote> prefix
2582 This action may be specified multiple times, in order to define multiple
2583 headers. This is rarely needed for the typical user. If you don't know what
2584 <quote>HTTP headers</quote> are, you definitely don't need to worry about this
2588 Headers added by this action are not modified by other actions.
2594 <term>Example usage:</term>
2596 <screen># Add a DNT ("Do not track") header to all requests,
2597 # event to those that already have one.
2599 # This is just an example, not a recommendation.
2601 # There is no reason to believe that user-tracking websites care
2602 # about the DNT header and depending on the User-Agent, adding the
2603 # header may make user-tracking easier.
2604 {+add-header{DNT: 1}}
2612 <!-- ~~~~~ New section ~~~~~ -->
2613 <sect3 renderas="sect4" id="block">
2614 <title>block</title>
2618 <term>Typical use:</term>
2620 <para>Block ads or other unwanted content</para>
2625 <term>Effect:</term>
2628 Requests for URLs to which this action applies are blocked, i.e. the
2629 requests are trapped by &my-app; and the requested URL is never retrieved,
2630 but is answered locally with a substitute page or image, as determined by
2632 linkend="handle-as-image">handle-as-image</link></literal>,
2634 linkend="set-image-blocker">set-image-blocker</link></literal>, and
2636 linkend="handle-as-empty-document">handle-as-empty-document</link></literal> actions.
2644 <!-- boolean, parameterized, Multi-value -->
2646 <para>Parameterized.</para>
2651 <term>Parameter:</term>
2653 <para>A block reason that should be given to the user.</para>
2661 <application>Privoxy</application> sends a special <quote>BLOCKED</quote> page
2662 for requests to blocked pages. This page contains the block reason given as
2663 parameter, a link to find out why the block action applies, and a click-through
2664 to the blocked content (the latter only if the force feature is available and
2668 A very important exception occurs if <emphasis>both</emphasis>
2669 <literal>block</literal> and <literal><link linkend="handle-as-image">handle-as-image</link></literal>,
2670 apply to the same request: it will then be replaced by an image. If
2671 <literal><link linkend="set-image-blocker">set-image-blocker</link></literal>
2672 (see below) also applies, the type of image will be determined by its parameter,
2673 if not, the standard checkerboard pattern is sent.
2676 It is important to understand this process, in order
2677 to understand how <application>Privoxy</application> deals with
2678 ads and other unwanted content. Blocking is a core feature, and one
2679 upon which various other features depend.
2682 The <literal><link linkend="filter">filter</link></literal>
2683 action can perform a very similar task, by <quote>blocking</quote>
2684 banner images and other content through rewriting the relevant URLs in the
2685 document's HTML source, so they don't get requested in the first place.
2686 Note that this is a totally different technique, and it's easy to confuse the two.
2692 <term>Example usage (section):</term>
2694 <screen>{+block{No nasty stuff for you.}}
2695 # Block and replace with "blocked" page
2696 .nasty-stuff.example.com
2698 {+block{Doubleclick banners.} +handle-as-image}
2699 # Block and replace with image
2703 {+block{Layered ads.} +handle-as-empty-document}
2704 # Block and then ignore
2705 adserver.example.net/.*\.js$</screen>
2714 <!-- ~~~~~ New section ~~~~~ -->
2715 <sect3 renderas="sect4" id="change-x-forwarded-for">
2716 <title>change-x-forwarded-for</title>
2720 <term>Typical use:</term>
2722 <para>Improve privacy by not forwarding the source of the request in the HTTP headers.</para>
2727 <term>Effect:</term>
2730 Deletes the <quote>X-Forwarded-For:</quote> HTTP header from the client request,
2738 <!-- Boolean, Parameterized, Multi-value -->
2740 <para>Parameterized.</para>
2745 <term>Parameter:</term>
2749 <para><quote>block</quote> to delete the header.</para>
2753 <quote>add</quote> to create the header (or append
2754 the client's IP address to an already existing one).
2765 It is safe and recommended to use <literal>block</literal>.
2768 Forwarding the source address of the request may make
2769 sense in some multi-user setups but is also a privacy risk.
2774 <term>Example usage:</term>
2776 <screen>+change-x-forwarded-for{block}</screen>
2782 <!-- ~~~~~ New section ~~~~~ -->
2783 <sect3 renderas="sect4" id="client-header-filter">
2784 <title>client-header-filter</title>
2788 <term>Typical use:</term>
2791 Rewrite or remove single client headers.
2797 <term>Effect:</term>
2800 All client headers to which this action applies are filtered on-the-fly through
2801 the specified regular expression based substitutions.
2808 <!-- boolean, parameterized, Multi-value -->
2810 <para>Multi-value.</para>
2815 <term>Parameter:</term>
2818 The name of a client-header filter, as defined in one of the
2819 <link linkend="filter-file">filter files</link>.
2828 Client-header filters are applied to each header on its own, not to
2829 all at once. This makes it easier to diagnose problems, but on the downside
2830 you can't write filters that only change header x if header y's value is z.
2831 You can do that by using tags though.
2834 Client-header filters are executed after the other header actions have finished
2835 and use their output as input.
2838 If the request URI gets changed, &my-app; will detect that and use the new
2839 one. This can be used to rewrite the request destination behind the client's
2840 back, for example to specify a Tor exit relay for certain requests.
2843 Please refer to the <link linkend="filter-file">filter file chapter</link>
2844 to learn which client-header filters are available by default, and how to
2852 <term>Example usage (section):</term>
2855 # Hide Tor exit notation in Host and Referer Headers
2856 {+client-header-filter{hide-tor-exit-notation}}
2866 <!-- ~~~~~ New section ~~~~~ -->
2867 <sect3 renderas="sect4" id="client-header-tagger">
2868 <title>client-header-tagger</title>
2872 <term>Typical use:</term>
2875 Block requests based on their headers.
2881 <term>Effect:</term>
2884 Client headers to which this action applies are filtered on-the-fly through
2885 the specified regular expression based substitutions, the result is used as
2893 <!-- boolean, parameterized, Multi-value -->
2895 <para>Multi-value.</para>
2900 <term>Parameter:</term>
2903 The name of a client-header tagger, as defined in one of the
2904 <link linkend="filter-file">filter files</link>.
2913 Client-header taggers are applied to each header on its own,
2914 and as the header isn't modified, each tagger <quote>sees</quote>
2918 Client-header taggers are the first actions that are executed
2919 and their tags can be used to control every other action.
2925 <term>Example usage (section):</term>
2928 # Tag every request with the User-Agent header
2929 {+client-header-tagger{user-agent}}
2932 # Tagging itself doesn't change the action
2933 # settings, sections with TAG patterns do:
2935 # If it's a download agent, use a different forwarding proxy,
2936 # show the real User-Agent and make sure resume works.
2937 {+forward-override{forward-socks5 10.0.0.2:2222 .} \
2938 -hide-if-modified-since \
2939 -overwrite-last-modified \
2944 TAG:^User-Agent: NetBSD-ftp/
2945 TAG:^User-Agent: Novell ZYPP Installer
2946 TAG:^User-Agent: RPM APT-HTTP/
2947 TAG:^User-Agent: fetch libfetch/
2948 TAG:^User-Agent: Ubuntu APT-HTTP/
2949 TAG:^User-Agent: MPlayer/
2953 # Tag all requests with the Range header set
2954 {+client-header-tagger{range-requests}}
2957 # Disable filtering for the tagged requests.
2959 # With filtering enabled Privoxy would remove the Range headers
2960 # to be able to filter the whole response. The downside is that
2961 # it prevents clients from resuming downloads or skipping over
2962 # parts of multimedia files.
2963 {-filter -deanimate-gifs}
2968 # Tag all requests with the client IP address
2970 # (Technically the client IP address isn't included in the
2971 # client headers but client-header taggers can set it anyway.
2972 # For details see the tagger in default.filter)
2973 {+client-header-tagger{client-ip-address}}
2976 # Change forwarding settings for requests coming from address 10.0.0.1
2977 {+forward-override{forward-socks5 127.0.1.2:2222 .}}
2978 TAG:^IP-ADDRESS: 10\.0\.0\.1$
2987 <!-- ~~~~~ New section ~~~~~ -->
2988 <sect3 renderas="sect4" id="content-type-overwrite">
2989 <title>content-type-overwrite</title>
2993 <term>Typical use:</term>
2995 <para>Stop useless download menus from popping up, or change the browser's rendering mode</para>
3000 <term>Effect:</term>
3003 Replaces the <quote>Content-Type:</quote> HTTP server header.
3010 <!-- Boolean, Parameterized, Multi-value -->
3012 <para>Parameterized.</para>
3017 <term>Parameter:</term>
3029 The <quote>Content-Type:</quote> HTTP server header is used by the
3030 browser to decide what to do with the document. The value of this
3031 header can cause the browser to open a download menu instead of
3032 displaying the document by itself, even if the document's format is
3033 supported by the browser.
3036 The declared content type can also affect which rendering mode
3037 the browser chooses. If XHTML is delivered as <quote>text/html</quote>,
3038 many browsers treat it as yet another broken HTML document.
3039 If it is send as <quote>application/xml</quote>, browsers with
3040 XHTML support will only display it, if the syntax is correct.
3043 If you see a web site that proudly uses XHTML buttons, but sets
3044 <quote>Content-Type: text/html</quote>, you can use &my-app;
3045 to overwrite it with <quote>application/xml</quote> and validate
3046 the web master's claim inside your XHTML-supporting browser.
3047 If the syntax is incorrect, the browser will complain loudly.
3050 You can also go the opposite direction: if your browser prints
3051 error messages instead of rendering a document falsely declared
3052 as XHTML, you can overwrite the content type with
3053 <quote>text/html</quote> and have it rendered as broken HTML document.
3056 By default <literal>content-type-overwrite</literal> only replaces
3057 <quote>Content-Type:</quote> headers that look like some kind of text.
3058 If you want to overwrite it unconditionally, you have to combine it with
3059 <literal><link linkend="force-text-mode">force-text-mode</link></literal>.
3060 This limitation exists for a reason, think twice before circumventing it.
3063 Most of the time it's easier to replace this action with a custom
3064 <literal><link linkend="server-header-filter">server-header filter</link></literal>.
3065 It allows you to activate it for every document of a certain site and it will still
3066 only replace the content types you aimed at.
3069 Of course you can apply <literal>content-type-overwrite</literal>
3070 to a whole site and then make URL based exceptions, but it's a lot
3071 more work to get the same precision.
3077 <term>Example usage (sections):</term>
3079 <screen># Check if www.example.net/ really uses valid XHTML
3080 { +content-type-overwrite{application/xml} }
3083 # but leave the content type unmodified if the URL looks like a style sheet
3084 {-content-type-overwrite}
3085 www.example.net/.*\.css$
3086 www.example.net/.*style
3094 <!-- ~~~~~ New section ~~~~~ -->
3095 <sect3 renderas="sect4" id="crunch-client-header">
3099 <title>crunch-client-header</title>
3103 <term>Typical use:</term>
3105 <para>Remove a client header <application>Privoxy</application> has no dedicated action for.</para>
3110 <term>Effect:</term>
3113 Deletes every header sent by the client that contains the string the user supplied as parameter.
3120 <!-- Boolean, Parameterized, Multi-value -->
3122 <para>Parameterized.</para>
3127 <term>Parameter:</term>
3139 This action allows you to block client headers for which no dedicated
3140 <application>Privoxy</application> action exists.
3141 <application>Privoxy</application> will remove every client header that
3142 contains the string you supplied as parameter.
3145 Regular expressions are <emphasis>not supported</emphasis> and you can't
3146 use this action to block different headers in the same request, unless
3147 they contain the same string.
3150 <literal>crunch-client-header</literal> is only meant for quick tests.
3151 If you have to block several different headers, or only want to modify
3152 parts of them, you should use a
3153 <literal><link linkend="client-header-filter">client-header filter</link></literal>.
3157 Don't block any header without understanding the consequences.
3164 <term>Example usage (section):</term>
3166 <screen># Block the non-existent "Privacy-Violation:" client header
3167 { +crunch-client-header{Privacy-Violation:} }
3176 <!-- ~~~~~ New section ~~~~~ -->
3177 <sect3 renderas="sect4" id="crunch-if-none-match">
3178 <title>crunch-if-none-match</title>
3184 <term>Typical use:</term>
3186 <para>Prevent yet another way to track the user's steps between sessions.</para>
3191 <term>Effect:</term>
3194 Deletes the <quote>If-None-Match:</quote> HTTP client header.
3201 <!-- Boolean, Parameterized, Multi-value -->
3203 <para>Boolean.</para>
3208 <term>Parameter:</term>
3220 Removing the <quote>If-None-Match:</quote> HTTP client header
3221 is useful for filter testing, where you want to force a real
3222 reload instead of getting status code <quote>304</quote> which
3223 would cause the browser to use a cached copy of the page.
3226 It is also useful to make sure the header isn't used as a cookie
3227 replacement (unlikely but possible).
3230 Blocking the <quote>If-None-Match:</quote> header shouldn't cause any
3231 caching problems, as long as the <quote>If-Modified-Since:</quote> header
3232 isn't blocked or missing as well.
3235 It is recommended to use this action together with
3236 <literal><link linkend="hide-if-modified-since">hide-if-modified-since</link></literal>
3238 <literal><link linkend="overwrite-last-modified">overwrite-last-modified</link></literal>.
3244 <term>Example usage (section):</term>
3246 <screen># Let the browser revalidate cached documents but don't
3247 # allow the server to use the revalidation headers for user tracking.
3248 {+hide-if-modified-since{-60} \
3249 +overwrite-last-modified{randomize} \
3250 +crunch-if-none-match}
3258 <!-- ~~~~~ New section ~~~~~ -->
3259 <sect3 renderas="sect4" id="crunch-incoming-cookies">
3260 <title>crunch-incoming-cookies</title>
3264 <term>Typical use:</term>
3267 Prevent the web server from setting HTTP cookies on your system
3273 <term>Effect:</term>
3276 Deletes any <quote>Set-Cookie:</quote> HTTP headers from server replies.
3283 <!-- Boolean, Parameterized, Multi-value -->
3285 <para>Boolean.</para>
3290 <term>Parameter:</term>
3302 This action is only concerned with <emphasis>incoming</emphasis> HTTP cookies. For
3303 <emphasis>outgoing</emphasis> HTTP cookies, use
3304 <literal><link linkend="crunch-outgoing-cookies">crunch-outgoing-cookies</link></literal>.
3305 Use <emphasis>both</emphasis> to disable HTTP cookies completely.
3308 It makes <emphasis>no sense at all</emphasis> to use this action in conjunction
3309 with the <literal><link linkend="session-cookies-only">session-cookies-only</link></literal> action,
3310 since it would prevent the session cookies from being set. See also
3311 <literal><link linkend="filter-content-cookies">filter-content-cookies</link></literal>.
3317 <term>Example usage:</term>
3319 <screen>+crunch-incoming-cookies</screen>
3326 <!-- ~~~~~ New section ~~~~~ -->
3327 <sect3 renderas="sect4" id="crunch-server-header">
3328 <title>crunch-server-header</title>
3334 <term>Typical use:</term>
3336 <para>Remove a server header <application>Privoxy</application> has no dedicated action for.</para>
3341 <term>Effect:</term>
3344 Deletes every header sent by the server that contains the string the user supplied as parameter.
3351 <!-- Boolean, Parameterized, Multi-value -->
3353 <para>Parameterized.</para>
3358 <term>Parameter:</term>
3370 This action allows you to block server headers for which no dedicated
3371 <application>Privoxy</application> action exists. <application>Privoxy</application>
3372 will remove every server header that contains the string you supplied as parameter.
3375 Regular expressions are <emphasis>not supported</emphasis> and you can't
3376 use this action to block different headers in the same request, unless
3377 they contain the same string.
3380 <literal>crunch-server-header</literal> is only meant for quick tests.
3381 If you have to block several different headers, or only want to modify
3382 parts of them, you should use a custom
3383 <literal><link linkend="server-header-filter">server-header filter</link></literal>.
3387 Don't block any header without understanding the consequences.
3394 <term>Example usage (section):</term>
3396 <screen># Crunch server headers that try to prevent caching
3397 { +crunch-server-header{no-cache} }
3405 <!-- ~~~~~ New section ~~~~~ -->
3406 <sect3 renderas="sect4" id="crunch-outgoing-cookies">
3407 <title>crunch-outgoing-cookies</title>
3411 <term>Typical use:</term>
3414 Prevent the web server from reading any HTTP cookies from your system
3420 <term>Effect:</term>
3423 Deletes any <quote>Cookie:</quote> HTTP headers from client requests.
3430 <!-- Boolean, Parameterized, Multi-value -->
3432 <para>Boolean.</para>
3437 <term>Parameter:</term>
3449 This action is only concerned with <emphasis>outgoing</emphasis> HTTP cookies. For
3450 <emphasis>incoming</emphasis> HTTP cookies, use
3451 <literal><link linkend="crunch-incoming-cookies">crunch-incoming-cookies</link></literal>.
3452 Use <emphasis>both</emphasis> to disable HTTP cookies completely.
3455 It makes <emphasis>no sense at all</emphasis> to use this action in conjunction
3456 with the <literal><link linkend="session-cookies-only">session-cookies-only</link></literal> action,
3457 since it would prevent the session cookies from being read.
3463 <term>Example usage:</term>
3465 <screen>+crunch-outgoing-cookies</screen>
3473 <!-- ~~~~~ New section ~~~~~ -->
3474 <sect3 renderas="sect4" id="deanimate-gifs">
3475 <title>deanimate-gifs</title>
3479 <term>Typical use:</term>
3481 <para>Stop those annoying, distracting animated GIF images.</para>
3486 <term>Effect:</term>
3489 De-animate GIF animations, i.e. reduce them to their first or last image.
3496 <!-- boolean, parameterized, Multi-value -->
3498 <para>Parameterized.</para>
3503 <term>Parameter:</term>
3506 <quote>last</quote> or <quote>first</quote>
3515 This will also shrink the images considerably (in bytes, not pixels!). If
3516 the option <quote>first</quote> is given, the first frame of the animation
3517 is used as the replacement. If <quote>last</quote> is given, the last
3518 frame of the animation is used instead, which probably makes more sense for
3519 most banner animations, but also has the risk of not showing the entire
3520 last frame (if it is only a delta to an earlier frame).
3523 You can safely use this action with patterns that will also match non-GIF
3524 objects, because no attempt will be made at anything that doesn't look like
3531 <term>Example usage:</term>
3533 <screen>+deanimate-gifs{last}</screen>
3539 <!-- ~~~~~ New section ~~~~~ -->
3540 <sect3 renderas="sect4" id="downgrade-http-version">
3541 <title>downgrade-http-version</title>
3545 <term>Typical use:</term>
3547 <para>Work around (very rare) problems with HTTP/1.1</para>
3552 <term>Effect:</term>
3555 Downgrades HTTP/1.1 client requests and server replies to HTTP/1.0.
3562 <!-- boolean, parameterized, Multi-value -->
3564 <para>Boolean.</para>
3569 <term>Parameter:</term>
3581 This is a left-over from the time when <application>Privoxy</application>
3582 didn't support important HTTP/1.1 features well. It is left here for the
3583 unlikely case that you experience HTTP/1.1-related problems with some server
3587 Note that enabling this action is only a workaround. It should not
3588 be enabled for sites that work without it. While it shouldn't break
3589 any pages, it has an (usually negative) performance impact.
3592 If you come across a site where enabling this action helps, please report it,
3593 so the cause of the problem can be analyzed. If the problem turns out to be
3594 caused by a bug in <application>Privoxy</application> it should be
3595 fixed so the following release works without the work around.
3601 <term>Example usage (section):</term>
3603 <screen>{+downgrade-http-version}
3604 problem-host.example.com</screen>
3611 <!-- ~~~~~ New section ~~~~~ -->
3612 <sect3 renderas="sect4" id="external-filter">
3613 <title>external-filter</title>
3617 <term>Typical use:</term>
3619 <para>Modify content using a programming language of your choice.</para>
3624 <term>Effect:</term>
3627 All instances of text-based type, most notably HTML and JavaScript, to which
3628 this action applies, can be filtered on-the-fly through the specified external
3630 By default plain text documents are exempted from filtering, because web
3631 servers often use the <literal>text/plain</literal> MIME type for all files
3632 whose type they don't know.)
3639 <!-- boolean, parameterized, Multi-value -->
3641 <para>Multi-value.</para>
3646 <term>Parameter:</term>
3649 The name of an external content filter, as defined in the
3650 <link linkend="filter-file">filter file</link>.
3651 External filters can be defined in one or more files as defined by the
3652 <literal><link linkend="filterfile">filterfile</link></literal>
3653 option in the <link linkend="config">config file</link>.
3656 When used in its negative form,
3657 and without parameters, <emphasis>all</emphasis> filtering with external
3658 filters is completely disabled.
3667 External filters are scripts or programs that can modify the content in
3668 case common <literal><link linkend="filter">filters</link></literal>
3669 aren't powerful enough. With the exception that this action doesn't
3670 use pcrs-based filters, the notes in the
3671 <literal><link linkend="filter">filter</link></literal> section apply.
3675 Currently external filters are executed with &my-app;'s privileges.
3676 Only use external filters you understand and trust.
3680 This feature is experimental, the <literal><link
3681 linkend="external-filter-syntax">syntax</link></literal>
3682 may change in the future.
3689 <term>Example usage:</term>
3691 <screen>+external-filter{fancy-filter}</screen>
3697 <!-- ~~~~~ New section ~~~~~ -->
3698 <sect3 renderas="sect4" id="fast-redirects">
3699 <title>fast-redirects</title>
3703 <term>Typical use:</term>
3705 <para>Fool some click-tracking scripts and speed up indirect links.</para>
3710 <term>Effect:</term>
3713 Detects redirection URLs and redirects the browser without contacting
3714 the redirection server first.
3721 <!-- boolean, parameterized, Multi-value -->
3723 <para>Parameterized.</para>
3728 <term>Parameter:</term>
3733 <quote>simple-check</quote> to just search for the string <quote>http://</quote>
3734 to detect redirection URLs.
3739 <quote>check-decoded-url</quote> to decode URLs (if necessary) before searching
3740 for redirection URLs.
3751 Many sites, like yahoo.com, don't just link to other sites. Instead, they
3752 will link to some script on their own servers, giving the destination as a
3753 parameter, which will then redirect you to the final target. URLs
3754 resulting from this scheme typically look like:
3755 <quote>http://www.example.org/click-tracker.cgi?target=http%3a//www.example.net/</quote>.
3758 Sometimes, there are even multiple consecutive redirects encoded in the
3759 URL. These redirections via scripts make your web browsing more traceable,
3760 since the server from which you follow such a link can see where you go
3761 to. Apart from that, valuable bandwidth and time is wasted, while your
3762 browser asks the server for one redirect after the other. Plus, it feeds
3766 This feature is currently not very smart and is scheduled for improvement.
3767 If it is enabled by default, you will have to create some exceptions to
3768 this action. It can lead to failures in several ways:
3771 Not every URLs with other URLs as parameters is evil.
3772 Some sites offer a real service that requires this information to work.
3773 For example a validation service needs to know, which document to validate.
3774 <literal>fast-redirects</literal> assumes that every URL parameter that
3775 looks like another URL is a redirection target, and will always redirect to
3776 the last one. Most of the time the assumption is correct, but if it isn't,
3777 the user gets redirected anyway.
3780 Another failure occurs if the URL contains other parameters after the URL parameter.
3782 <quote>http://www.example.org/?redirect=http%3a//www.example.net/&foo=bar</quote>.
3783 contains the redirection URL <quote>http://www.example.net/</quote>,
3784 followed by another parameter. <literal>fast-redirects</literal> doesn't know that
3785 and will cause a redirect to <quote>http://www.example.net/&foo=bar</quote>.
3786 Depending on the target server configuration, the parameter will be silently ignored
3787 or lead to a <quote>page not found</quote> error. You can prevent this problem by
3788 first using the <literal><link linkend="redirect">redirect</link></literal> action
3789 to remove the last part of the URL, but it requires a little effort.
3792 To detect a redirection URL, <literal>fast-redirects</literal> only
3793 looks for the string <quote>http://</quote>, either in plain text
3794 (invalid but often used) or encoded as <quote>http%3a//</quote>.
3795 Some sites use their own URL encoding scheme, encrypt the address
3796 of the target server or replace it with a database id. In theses cases
3797 <literal>fast-redirects</literal> is fooled and the request reaches the
3798 redirection server where it probably gets logged.
3804 <term>Example usage:</term>
3807 { +fast-redirects{simple-check} }
3810 { +fast-redirects{check-decoded-url} }
3811 another.example.com/testing</screen>
3819 <!-- ~~~~~ New section ~~~~~ -->
3820 <sect3 renderas="sect4" id="filter">
3821 <title>filter</title>
3825 <term>Typical use:</term>
3827 <para>Get rid of HTML and JavaScript annoyances, banner advertisements (by size),
3828 do fun text replacements, add personalized effects, etc.</para>
3833 <term>Effect:</term>
3836 All instances of text-based type, most notably HTML and JavaScript, to which
3837 this action applies, can be filtered on-the-fly through the specified regular
3838 expression based substitutions. (Note: as of version 3.0.3 plain text documents
3839 are exempted from filtering, because web servers often use the
3840 <literal>text/plain</literal> MIME type for all files whose type they don't know.)
3847 <!-- boolean, parameterized, Multi-value -->
3849 <para>Multi-value.</para>
3854 <term>Parameter:</term>
3857 The name of a content filter, as defined in the <link linkend="filter-file">filter file</link>.
3858 Filters can be defined in one or more files as defined by the
3859 <literal><link linkend="filterfile">filterfile</link></literal>
3860 option in the <link linkend="config">config file</link>.
3861 <filename>default.filter</filename> is the collection of filters
3862 supplied by the developers. Locally defined filters should go
3863 in their own file, such as <filename>user.filter</filename>.
3866 When used in its negative form,
3867 and without parameters, <emphasis>all</emphasis> filtering is completely disabled.
3876 For your convenience, there are a number of pre-defined filters available
3877 in the distribution filter file that you can use. See the examples below for
3881 Filtering requires buffering the page content, which may appear to
3882 slow down page rendering since nothing is displayed until all content has
3883 passed the filters. (The total time until the page is completely rendered
3884 doesn't change much, but it may be perceived as slower since the page is
3885 not incrementally displayed.)
3886 This effect will be more noticeable on slower connections.
3889 <quote>Rolling your own</quote>
3890 filters requires a knowledge of
3891 <ulink url="http://en.wikipedia.org/wiki/Regular_expressions"><quote>Regular
3892 Expressions</quote></ulink> and
3893 <ulink url="http://en.wikipedia.org/wiki/Html"><quote>HTML</quote></ulink>.
3894 This is very powerful feature, and potentially very intrusive.
3895 Filters should be used with caution, and where an equivalent
3896 <quote>action</quote> is not available.
3899 The amount of data that can be filtered is limited to the
3900 <literal><link linkend="buffer-limit">buffer-limit</link></literal>
3901 option in the main <link linkend="config">config file</link>. The
3902 default is 4096 KB (4 Megs). Once this limit is exceeded, the buffered
3903 data, and all pending data, is passed through unfiltered.
3906 Inappropriate MIME types, such as zipped files, are not filtered at all.
3907 (Again, only text-based types except plain text). Encrypted SSL data
3908 (from HTTPS servers) cannot be filtered either, since this would violate
3909 the integrity of the secure transaction. In some situations it might
3910 be necessary to protect certain text, like source code, from filtering
3911 by defining appropriate <literal>-filter</literal> exceptions.
3914 Compressed content can't be filtered either, but if &my-app;
3915 is compiled with zlib support and a supported compression algorithm
3916 is used (gzip or deflate), &my-app; can first decompress the content
3920 If you use a &my-app; version without zlib support, but want filtering to work on
3921 as much documents as possible, even those that would normally be sent compressed,
3922 you must use the <literal><link linkend="prevent-compression">prevent-compression</link></literal>
3923 action in conjunction with <literal>filter</literal>.
3926 Content filtering can achieve some of the same effects as the
3927 <literal><link linkend="block">block</link></literal>
3928 action, i.e. it can be used to block ads and banners. But the mechanism
3929 works quite differently. One effective use, is to block ad banners
3930 based on their size (see below), since many of these seem to be somewhat
3934 <link linkend="contact">Feedback</link> with suggestions for new or
3935 improved filters is particularly welcome!
3938 The below list has only the names and a one-line description of each
3939 predefined filter. There are <link linkend="predefined-filters">more
3940 verbose explanations</link> of what these filters do in the <link
3941 linkend="filter-file">filter file chapter</link>.
3947 <term>Example usage (with filters from the distribution <filename>default.filter</filename> file).
3948 See <link linkend="PREDEFINED-FILTERS">the Predefined Filters section</link> for
3949 more explanation on each:</term>
3952 <anchor id="filter-js-annoyances">
3954 <screen>+filter{js-annoyances} # Get rid of particularly annoying JavaScript abuse.</screen>
3956 <anchor id="filter-js-events">
3958 <screen>+filter{js-events} # Kill JavaScript event bindings and timers (Radically destructive! Only for extra nasty sites).</screen>
3960 <anchor id="filter-html-annoyances">
3962 <screen>+filter{html-annoyances} # Get rid of particularly annoying HTML abuse.</screen>
3964 <anchor id="filter-content-cookies">
3966 <screen>+filter{content-cookies} # Kill cookies that come in the HTML or JS content.</screen>
3968 <anchor id="filter-refresh-tags">
3970 <screen>+filter{refresh-tags} # Kill automatic refresh tags if refresh time is larger than 9 seconds.</screen>
3972 <anchor id="filter-unsolicited-popups">
3974 <screen>+filter{unsolicited-popups} # Disable only unsolicited pop-up windows.</screen>
3976 <anchor id="filter-all-popups">
3978 <screen>+filter{all-popups} # Kill all popups in JavaScript and HTML.</screen>
3980 <anchor id="filter-img-reorder">
3982 <screen>+filter{img-reorder} # Reorder attributes in <img> tags to make the banners-by-* filters more effective.</screen>
3984 <anchor id="filter-banners-by-size">
3986 <screen>+filter{banners-by-size} # Kill banners by size.</screen>
3988 <anchor id="filter-banners-by-link">
3990 <screen>+filter{banners-by-link} # Kill banners by their links to known clicktrackers.</screen>
3992 <anchor id="filter-webbugs">
3994 <screen>+filter{webbugs} # Squish WebBugs (1x1 invisible GIFs used for user tracking).</screen>
3996 <anchor id="filter-tiny-textforms">
3998 <screen>+filter{tiny-textforms} # Extend those tiny textareas up to 40x80 and kill the hard wrap.</screen>
4000 <anchor id="filter-jumping-windows">
4002 <screen>+filter{jumping-windows} # Prevent windows from resizing and moving themselves.</screen>
4004 <anchor id="filter-frameset-borders">
4006 <screen>+filter{frameset-borders} # Give frames a border and make them resizable.</screen>
4008 <anchor id="filter-iframes">
4010 <screen>+filter{iframes} # Removes all detected iframes. Should only be enabled for individual sites.</screen>
4012 <anchor id="filter-demoronizer">
4014 <screen>+filter{demoronizer} # Fix MS's non-standard use of standard charsets.</screen>
4016 <anchor id="filter-shockwave-flash">
4018 <screen>+filter{shockwave-flash} # Kill embedded Shockwave Flash objects.</screen>
4020 <anchor id="filter-quicktime-kioskmode">
4022 <screen>+filter{quicktime-kioskmode} # Make Quicktime movies saveable.</screen>
4024 <anchor id="filter-fun">
4026 <screen>+filter{fun} # Text replacements for subversive browsing fun!</screen>
4028 <anchor id="filter-crude-parental">
4030 <screen>+filter{crude-parental} # Crude parental filtering. Note that this filter doesn't work reliably.</screen>
4032 <anchor id="filter-ie-exploits">
4034 <screen>+filter{ie-exploits} # Disable some known Internet Explorer bug exploits.</screen>
4036 <anchor id="filter-site-specifics">
4038 <screen>+filter{site-specifics} # Cure for site-specific problems. Don't apply generally!</screen>
4040 <anchor id="filter-no-ping">
4042 <screen>+filter{no-ping} # Removes non-standard ping attributes in <a> and <area> tags.</screen>
4044 <anchor id="filter-google">
4046 <screen>+filter{google} # CSS-based block for Google text ads. Also removes a width limitation and the toolbar advertisement.</screen>
4048 <anchor id="filter-yahoo">
4050 <screen>+filter{yahoo} # CSS-based block for Yahoo text ads. Also removes a width limitation.</screen>
4052 <anchor id="filter-msn">
4054 <screen>+filter{msn} # CSS-based block for MSN text ads. Also removes tracking URLs and a width limitation.</screen>
4056 <anchor id="filter-blogspot">
4058 <screen>+filter{blogspot} # Cleans up some Blogspot blogs. Read the fine print before using this.</screen>
4065 <!-- ~~~~~ New section ~~~~~ -->
4066 <sect3 renderas="sect4" id="force-text-mode">
4067 <title>force-text-mode</title>
4073 <term>Typical use:</term>
4075 <para>Force <application>Privoxy</application> to treat a document as if it was in some kind of <emphasis>text</emphasis> format. </para>
4080 <term>Effect:</term>
4083 Declares a document as text, even if the <quote>Content-Type:</quote> isn't detected as such.
4090 <!-- Boolean, Parameterized, Multi-value -->
4092 <para>Boolean.</para>
4097 <term>Parameter:</term>
4109 As explained <literal><link linkend="filter">above</link></literal>,
4110 <application>Privoxy</application> tries to only filter files that are
4111 in some kind of text format. The same restrictions apply to
4112 <literal><link linkend="content-type-overwrite">content-type-overwrite</link></literal>.
4113 <literal>force-text-mode</literal> declares a document as text,
4114 without looking at the <quote>Content-Type:</quote> first.
4118 Think twice before activating this action. Filtering binary data
4119 with regular expressions can cause file damage.
4126 <term>Example usage:</term>
4137 <!-- ~~~~~ New section ~~~~~ -->
4138 <sect3 renderas="sect4" id="forward-override">
4139 <title>forward-override</title>
4145 <term>Typical use:</term>
4147 <para>Change the forwarding settings based on User-Agent or request origin</para>
4152 <term>Effect:</term>
4155 Overrules the forward directives in the configuration file.
4162 <!-- Boolean, Parameterized, Multi-value -->
4164 <para>Parameterized.</para>
4169 <term>Parameter:</term>
4173 <para><quote>forward .</quote> to use a direct connection without any additional proxies.</para>
4177 <quote>forward 127.0.0.1:8123</quote> to use the HTTP proxy listening at 127.0.0.1 port 8123.
4182 <quote>forward-socks4a 127.0.0.1:9050 .</quote> to use the socks4a proxy listening at
4183 127.0.0.1 port 9050. Replace <quote>forward-socks4a</quote> with <quote>forward-socks4</quote>
4184 to use a socks4 connection (with local DNS resolution) instead, use <quote>forward-socks5</quote>
4185 for socks5 connections (with remote DNS resolution).
4190 <quote>forward-socks4a 127.0.0.1:9050 proxy.example.org:8000</quote> to use the socks4a proxy
4191 listening at 127.0.0.1 port 9050 to reach the HTTP proxy listening at proxy.example.org port 8000.
4192 Replace <quote>forward-socks4a</quote> with <quote>forward-socks4</quote> to use a socks4 connection
4193 (with local DNS resolution) instead, use <quote>forward-socks5</quote>
4194 for socks5 connections (with remote DNS resolution).
4199 <quote>forward-webserver 127.0.0.1:80</quote> to use the HTTP
4200 server listening at 127.0.0.1 port 80 without adjusting the
4204 This makes it more convenient to use Privoxy to make
4205 existing websites available as onion services as well.
4208 Many websites serve content with hardcoded URLs and
4209 can't be easily adjusted to change the domain based
4210 on the one used by the client.
4213 Putting Privoxy between Tor and the webserver (or an stunnel
4214 that forwards to the webserver) allows to rewrite headers and
4215 content to make client and server happy at the same time.
4218 Using Privoxy for webservers that are only reachable through
4219 onion addresses and whose location is supposed to be secret
4220 is not recommended and should not be necessary anyway.
4231 This action takes parameters similar to the
4232 <link linkend="forwarding">forward</link> directives in the configuration
4233 file, but without the URL pattern. It can be used as replacement, but normally it's only
4234 used in cases where matching based on the request URL isn't sufficient.
4238 Please read the description for the <link linkend="forwarding">forward</link> directives before
4239 using this action. Forwarding to the wrong people will reduce your privacy and increase the
4240 chances of man-in-the-middle attacks.
4243 If the ports are missing or invalid, default values will be used. This might change
4244 in the future and you shouldn't rely on it. Otherwise incorrect syntax causes Privoxy
4245 to exit. Due to design limitations, invalid parameter syntax isn't detected until the
4246 action is used the first time.
4249 Use the <ulink url="http://config.privoxy.org/show-url-info">show-url-info CGI page</ulink>
4250 to verify that your forward settings do what you thought the do.
4257 <term>Example usage:</term>
4260 # Use an ssh tunnel for requests previously tagged as
4261 # <quote>User-Agent: fetch libfetch/2.0</quote> and make sure
4262 # resuming downloads continues to work.
4264 # This way you can continue to use Tor for your normal browsing,
4265 # without overloading the Tor network with your FreeBSD ports updates
4266 # or downloads of bigger files like ISOs.
4268 # Note that HTTP headers are easy to fake and therefore their
4269 # values are as (un)trustworthy as your clients and users.
4270 {+forward-override{forward-socks5 10.0.0.2:2222 .} \
4271 -hide-if-modified-since \
4272 -overwrite-last-modified \
4274 TAG:^User-Agent: fetch libfetch/2\.0$
4282 <!-- ~~~~~ New section ~~~~~ -->
4283 <sect3 renderas="sect4" id="handle-as-empty-document">
4284 <title>handle-as-empty-document</title>
4290 <term>Typical use:</term>
4292 <para>Mark URLs that should be replaced by empty documents <emphasis>if they get blocked</emphasis></para>
4297 <term>Effect:</term>
4300 This action alone doesn't do anything noticeable. It just marks URLs.
4301 If the <literal><link linkend="block">block</link></literal> action <emphasis>also applies</emphasis>,
4302 the presence or absence of this mark decides whether an HTML <quote>BLOCKED</quote>
4303 page, or an empty document will be sent to the client as a substitute for the blocked content.
4304 The <emphasis>empty</emphasis> document isn't literally empty, but actually contains a single space.
4311 <!-- Boolean, Parameterized, Multi-value -->
4313 <para>Boolean.</para>
4318 <term>Parameter:</term>
4330 Some browsers complain about syntax errors if JavaScript documents
4331 are blocked with <application>Privoxy's</application>
4332 default HTML page; this option can be used to silence them.
4333 And of course this action can also be used to eliminate the &my-app;
4334 BLOCKED message in frames.
4337 The content type for the empty document can be specified with
4338 <literal><link linkend="content-type-overwrite">content-type-overwrite{}</link></literal>,
4339 but usually this isn't necessary.
4345 <term>Example usage:</term>
4347 <screen># Block all documents on example.org that end with ".js",
4348 # but send an empty document instead of the usual HTML message.
4349 {+block{Blocked JavaScript} +handle-as-empty-document}
4358 <!-- ~~~~~ New section ~~~~~ -->
4359 <sect3 renderas="sect4" id="handle-as-image">
4360 <title>handle-as-image</title>
4364 <term>Typical use:</term>
4366 <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>
4371 <term>Effect:</term>
4374 This action alone doesn't do anything noticeable. It just marks URLs as images.
4375 If the <literal><link linkend="block">block</link></literal> action <emphasis>also applies</emphasis>,
4376 the presence or absence of this mark decides whether an HTML <quote>blocked</quote>
4377 page, or a replacement image (as determined by the <literal><link
4378 linkend="set-image-blocker">set-image-blocker</link></literal> action) will be sent to the
4379 client as a substitute for the blocked content.
4386 <!-- Boolean, Parameterized, Multi-value -->
4388 <para>Boolean.</para>
4393 <term>Parameter:</term>
4405 The below generic example section is actually part of <filename>default.action</filename>.
4406 It marks all URLs with well-known image file name extensions as images and should
4410 Users will probably only want to use the handle-as-image action in conjunction with
4411 <literal><link linkend="block">block</link></literal>, to block sources of banners, whose URLs don't
4412 reflect the file type, like in the second example section.
4415 Note that you cannot treat HTML pages as images in most cases. For instance, (in-line) ad
4416 frames require an HTML page to be sent, or they won't display properly.
4417 Forcing <literal>handle-as-image</literal> in this situation will not replace the
4418 ad frame with an image, but lead to error messages.
4424 <term>Example usage (sections):</term>
4426 <screen># Generic image extensions:
4429 /.*\.(gif|jpg|jpeg|png|bmp|ico)$
4431 # These don't look like images, but they're banners and should be
4432 # blocked as images:
4434 {+block{Nasty banners.} +handle-as-image}
4435 nasty-banner-server.example.com/junk.cgi\?output=trash
4443 <!-- ~~~~~ New section ~~~~~ -->
4444 <sect3 renderas="sect4" id="hide-accept-language">
4445 <title>hide-accept-language</title>
4451 <term>Typical use:</term>
4453 <para>Pretend to use different language settings.</para>
4458 <term>Effect:</term>
4461 Deletes or replaces the <quote>Accept-Language:</quote> HTTP header in client requests.
4468 <!-- Boolean, Parameterized, Multi-value -->
4470 <para>Parameterized.</para>
4475 <term>Parameter:</term>
4478 Keyword: <quote>block</quote>, or any user defined value.
4487 Faking the browser's language settings can be useful to make a
4488 foreign User-Agent set with
4489 <literal><link linkend="hide-user-agent">hide-user-agent</link></literal>
4493 However some sites with content in different languages check the
4494 <quote>Accept-Language:</quote> to decide which one to take by default.
4495 Sometimes it isn't possible to later switch to another language without
4496 changing the <quote>Accept-Language:</quote> header first.
4499 Therefore it's a good idea to either only change the
4500 <quote>Accept-Language:</quote> header to languages you understand,
4501 or to languages that aren't wide spread.
4504 Before setting the <quote>Accept-Language:</quote> header
4505 to a rare language, you should consider that it helps to
4506 make your requests unique and thus easier to trace.
4507 If you don't plan to change this header frequently,
4508 you should stick to a common language.
4514 <term>Example usage (section):</term>
4516 <screen># Pretend to use Canadian language settings.
4517 {+hide-accept-language{en-ca} \
4518 +hide-user-agent{Mozilla/5.0 (X11; U; OpenBSD i386; en-CA; rv:1.8.0.4) Gecko/20060628 Firefox/1.5.0.4} \
4527 <!-- ~~~~~ New section ~~~~~ -->
4528 <sect3 renderas="sect4" id="hide-content-disposition">
4529 <title>hide-content-disposition</title>
4535 <term>Typical use:</term>
4537 <para>Prevent download menus for content you prefer to view inside the browser.</para>
4542 <term>Effect:</term>
4545 Deletes or replaces the <quote>Content-Disposition:</quote> HTTP header set by some servers.
4552 <!-- Boolean, Parameterized, Multi-value -->
4554 <para>Parameterized.</para>
4559 <term>Parameter:</term>
4562 Keyword: <quote>block</quote>, or any user defined value.
4571 Some servers set the <quote>Content-Disposition:</quote> HTTP header for
4572 documents they assume you want to save locally before viewing them.
4573 The <quote>Content-Disposition:</quote> header contains the file name
4574 the browser is supposed to use by default.
4577 In most browsers that understand this header, it makes it impossible to
4578 <emphasis>just view</emphasis> the document, without downloading it first,
4579 even if it's just a simple text file or an image.
4582 Removing the <quote>Content-Disposition:</quote> header helps
4583 to prevent this annoyance, but some browsers additionally check the
4584 <quote>Content-Type:</quote> header, before they decide if they can
4585 display a document without saving it first. In these cases, you have
4586 to change this header as well, before the browser stops displaying
4590 It is also possible to change the server's file name suggestion
4591 to another one, but in most cases it isn't worth the time to set
4595 This action will probably be removed in the future,
4596 use server-header filters instead.
4602 <term>Example usage:</term>
4604 <screen># Disarm the download link in Sourceforge's patch tracker
4606 +content-type-overwrite{text/plain}\
4607 +hide-content-disposition{block} }
4608 .sourceforge.net/tracker/download\.php</screen>
4615 <!-- ~~~~~ New section ~~~~~ -->
4616 <sect3 renderas="sect4" id="hide-if-modified-since">
4617 <title>hide-if-modified-since</title>
4623 <term>Typical use:</term>
4625 <para>Prevent yet another way to track the user's steps between sessions.</para>
4630 <term>Effect:</term>
4633 Deletes the <quote>If-Modified-Since:</quote> HTTP client header or modifies its value.
4640 <!-- Boolean, Parameterized, Multi-value -->
4642 <para>Parameterized.</para>
4647 <term>Parameter:</term>
4650 Keyword: <quote>block</quote>, or a user defined value that specifies a range of hours.
4659 Removing this header is useful for filter testing, where you want to force a real
4660 reload instead of getting status code <quote>304</quote>, which would cause the
4661 browser to use a cached copy of the page.
4664 Instead of removing the header, <literal>hide-if-modified-since</literal> can
4665 also add or subtract a random amount of time to/from the header's value.
4666 You specify a range of minutes where the random factor should be chosen from and
4667 <application>Privoxy</application> does the rest. A negative value means
4668 subtracting, a positive value adding.
4671 Randomizing the value of the <quote>If-Modified-Since:</quote> makes
4672 it less likely that the server can use the time as a cookie replacement,
4673 but you will run into caching problems if the random range is too high.
4676 It is a good idea to only use a small negative value and let
4677 <literal><link linkend="overwrite-last-modified">overwrite-last-modified</link></literal>
4678 handle the greater changes.
4681 It is also recommended to use this action together with
4682 <literal><link linkend="crunch-if-none-match">crunch-if-none-match</link></literal>,
4683 otherwise it's more or less pointless.
4689 <term>Example usage (section):</term>
4691 <screen># Let the browser revalidate but make tracking based on the time less likely.
4692 {+hide-if-modified-since{-60} \
4693 +overwrite-last-modified{randomize} \
4694 +crunch-if-none-match}
4702 <!-- ~~~~~ New section ~~~~~ -->
4703 <sect3 renderas="sect4" id="hide-from-header">
4704 <title>hide-from-header</title>
4708 <term>Typical use:</term>
4710 <para>Keep your (old and ill) browser from telling web servers your email address</para>
4715 <term>Effect:</term>
4718 Deletes any existing <quote>From:</quote> HTTP header, or replaces it with the
4726 <!-- Boolean, Parameterized, Multi-value -->
4728 <para>Parameterized.</para>
4733 <term>Parameter:</term>
4736 Keyword: <quote>block</quote>, or any user defined value.
4745 The keyword <quote>block</quote> will completely remove the header
4746 (not to be confused with the <literal><link linkend="block">block</link></literal>
4750 Alternately, you can specify any value you prefer to be sent to the web
4751 server. If you do, it is a matter of fairness not to use any address that
4752 is actually used by a real person.
4755 This action is rarely needed, as modern web browsers don't send
4756 <quote>From:</quote> headers anymore.
4762 <term>Example usage:</term>
4764 <screen>+hide-from-header{block}</screen>
4766 <screen>+hide-from-header{spam-me-senseless@sittingduck.example.com}</screen>
4773 <!-- ~~~~~ New section ~~~~~ -->
4774 <sect3 renderas="sect4" id="hide-referrer">
4775 <title>hide-referrer</title>
4776 <anchor id="hide-referer">
4779 <term>Typical use:</term>
4781 <para>Conceal which link you followed to get to a particular site</para>
4786 <term>Effect:</term>
4789 Deletes the <quote>Referer:</quote> (sic) HTTP header from the client request,
4790 or replaces it with a forged one.
4797 <!-- Boolean, Parameterized, Multi-value -->
4799 <para>Parameterized.</para>
4804 <term>Parameter:</term>
4808 <para><quote>conditional-block</quote> to delete the header completely if the host has changed.</para>
4811 <para><quote>conditional-forge</quote> to forge the header if the host has changed.</para>
4814 <para><quote>block</quote> to delete the header unconditionally.</para>
4817 <para><quote>forge</quote> to pretend to be coming from the homepage of the server we are talking to.</para>
4820 <para>Any other string to set a user defined referrer.</para>
4830 <literal>conditional-block</literal> is the only parameter,
4831 that isn't easily detected in the server's log file. If it blocks the
4832 referrer, the request will look like the visitor used a bookmark or
4833 typed in the address directly.
4836 Leaving the referrer unmodified for requests on the same host
4837 allows the server owner to see the visitor's <quote>click path</quote>,
4838 but in most cases she could also get that information by comparing
4839 other parts of the log file: for example the User-Agent if it isn't
4840 a very common one, or the user's IP address if it doesn't change between
4844 Always blocking the referrer, or using a custom one, can lead to
4845 failures on servers that check the referrer before they answer any
4846 requests, in an attempt to prevent their content from being
4847 embedded or linked to elsewhere.
4850 Both <literal>conditional-block</literal> and <literal>forge</literal>
4851 will work with referrer checks, as long as content and valid referring page
4852 are on the same host. Most of the time that's the case.
4855 <literal>hide-referer</literal> is an alternate spelling of
4856 <literal>hide-referrer</literal> and the two can be can be freely
4857 substituted with each other. (<quote>referrer</quote> is the
4858 correct English spelling, however the HTTP specification has a bug - it
4859 requires it to be spelled as <quote>referer</quote>.)
4865 <term>Example usage:</term>
4867 <screen>+hide-referrer{forge}</screen>
4869 <screen>+hide-referrer{http://www.yahoo.com/}</screen>
4876 <!-- ~~~~~ New section ~~~~~ -->
4877 <sect3 renderas="sect4" id="hide-user-agent">
4878 <title>hide-user-agent</title>
4882 <term>Typical use:</term>
4884 <para>Try to conceal your type of browser and client operating system</para>
4889 <term>Effect:</term>
4892 Replaces the value of the <quote>User-Agent:</quote> HTTP header
4893 in client requests with the specified value.
4900 <!-- Boolean, Parameterized, Multi-value -->
4902 <para>Parameterized.</para>
4907 <term>Parameter:</term>
4910 Any user-defined string.
4920 This can lead to problems on web sites that depend on looking at this header in
4921 order to customize their content for different browsers (which, by the
4922 way, is <emphasis>NOT</emphasis> the right thing to do: good web sites
4923 work browser-independently).
4927 Using this action in multi-user setups or wherever different types of
4928 browsers will access the same <application>Privoxy</application> is
4929 <emphasis>not recommended</emphasis>. In single-user, single-browser
4930 setups, you might use it to delete your OS version information from
4931 the headers, because it is an invitation to exploit known bugs for your
4932 OS. It is also occasionally useful to forge this in order to access
4933 sites that won't let you in otherwise (though there may be a good
4934 reason in some cases).
4937 More information on known user-agent strings can be found at
4938 <ulink url="http://www.user-agents.org/">http://www.user-agents.org/</ulink>
4940 <ulink url="http://en.wikipedia.org/wiki/User_agent">http://en.wikipedia.org/wiki/User_agent</ulink>.
4946 <term>Example usage:</term>
4948 <screen>+hide-user-agent{Netscape 6.1 (X11; I; Linux 2.4.18 i686)}</screen>
4955 <!-- ~~~~~ New section ~~~~~ -->
4956 <sect3 renderas="sect4" id="limit-connect">
4957 <title>limit-connect</title>
4961 <term>Typical use:</term>
4963 <para>Prevent abuse of <application>Privoxy</application> as a TCP proxy relay or disable SSL for untrusted sites</para>
4968 <term>Effect:</term>
4971 Specifies to which ports HTTP CONNECT requests are allowable.
4978 <!-- Boolean, Parameterized, Multi-value -->
4980 <para>Parameterized.</para>
4985 <term>Parameter:</term>
4988 A comma-separated list of ports or port ranges (the latter using dashes, with the minimum
4989 defaulting to 0 and the maximum to 65K).
4998 By default, i.e. if no <literal>limit-connect</literal> action applies,
4999 <application>Privoxy</application> allows HTTP CONNECT requests to all
5000 ports. Use <literal>limit-connect</literal> if fine-grained control
5001 is desired for some or all destinations.
5004 The CONNECT methods exists in HTTP to allow access to secure websites
5005 (<quote>https://</quote> URLs) through proxies. It works very simply:
5006 the proxy connects to the server on the specified port, and then
5007 short-circuits its connections to the client and to the remote server.
5008 This means CONNECT-enabled proxies can be used as TCP relays very easily.
5011 <application>Privoxy</application> relays HTTPS traffic without seeing
5012 the decoded content. Websites can leverage this limitation to circumvent &my-app;'s
5013 filters. By specifying an invalid port range you can disable HTTPS entirely.
5019 <term>Example usages:</term>
5021 <!-- I had trouble getting the spacing to look right in my browser -->
5022 <!-- I probably have the wrong font setup, bollocks. -->
5023 <!-- Apparently the emphasis tag uses a proportional font no matter what -->
5024 <screen>+limit-connect{443} # Port 443 is OK.
5025 +limit-connect{80,443} # Ports 80 and 443 are OK.
5026 +limit-connect{-3, 7, 20-100, 500-} # Ports less than 3, 7, 20 to 100 and above 500 are OK.
5027 +limit-connect{-} # All ports are OK
5028 +limit-connect{,} # No HTTPS/SSL traffic is allowed</screen>
5035 <!-- ~~~~~ New section ~~~~~ -->
5036 <sect3 renderas="sect4" id="limit-cookie-lifetime">
5037 <title>limit-cookie-lifetime</title>
5041 <term>Typical use:</term>
5043 <para>Limit the lifetime of HTTP cookies to a couple of minutes or hours.</para>
5048 <term>Effect:</term>
5051 Overwrites the expires field in Set-Cookie server headers if it's above the specified limit.
5058 <!-- Boolean, Parameterized, Multi-value -->
5060 <para>Parameterized.</para>
5065 <term>Parameter:</term>
5068 The lifetime limit in minutes, or 0.
5077 This action reduces the lifetime of HTTP cookies coming from the
5078 server to the specified number of minutes, starting from the time
5079 the cookie passes Privoxy.
5082 Cookies with a lifetime below the limit are not modified.
5083 The lifetime of session cookies is set to the specified limit.
5086 The effect of this action depends on the server.
5089 In case of servers which refresh their cookies with each response
5090 (or at least frequently), the lifetime limit set by this action
5092 Thus, a session associated with the cookie continues to work with
5093 this action enabled, as long as a new request is made before the
5094 last limit set is reached.
5097 However, some servers send their cookies once, with a lifetime of several
5098 years (the year 2037 is a popular choice), and do not refresh them
5099 until a certain event in the future, for example the user logging out.
5100 In this case this action may limit the absolute lifetime of the session,
5101 even if requests are made frequently.
5104 If the parameter is <quote>0</quote>, this action behaves like
5105 <literal><link linkend="session-cookies-only">session-cookies-only</link></literal>.
5111 <term>Example usages:</term>
5113 <screen>+limit-cookie-lifetime{60}</screen>
5119 <!-- ~~~~~ New section ~~~~~ -->
5120 <sect3 renderas="sect4" id="prevent-compression">
5121 <title>prevent-compression</title>
5125 <term>Typical use:</term>
5128 Ensure that servers send the content uncompressed, so it can be
5129 passed through <literal><link linkend="filter">filter</link></literal>s.
5135 <term>Effect:</term>
5138 Removes the Accept-Encoding header which can be used to ask for compressed transfer.
5145 <!-- Boolean, Parameterized, Multi-value -->
5147 <para>Boolean.</para>
5152 <term>Parameter:</term>
5164 More and more websites send their content compressed by default, which
5165 is generally a good idea and saves bandwidth. But the <literal><link
5166 linkend="filter">filter</link></literal> and
5167 <literal><link linkend="deanimate-gifs">deanimate-gifs</link></literal>
5168 actions need access to the uncompressed data.
5171 When compiled with zlib support (available since &my-app; 3.0.7), content that should be
5172 filtered is decompressed on-the-fly and you don't have to worry about this action.
5173 If you are using an older &my-app; version, or one that hasn't been compiled with zlib
5174 support, this action can be used to convince the server to send the content uncompressed.
5177 Most text-based instances compress very well, the size is seldom decreased by less than 50%,
5178 for markup-heavy instances like news feeds saving more than 90% of the original size isn't
5182 Not using compression will therefore slow down the transfer, and you should only
5183 enable this action if you really need it. As of &my-app; 3.0.7 it's disabled in all
5184 predefined action settings.
5187 Note that some (rare) ill-configured sites don't handle requests for uncompressed
5188 documents correctly. Broken PHP applications tend to send an empty document body,
5189 some IIS versions only send the beginning of the content. If you enable
5190 <literal>prevent-compression</literal> per default, you might want to add
5191 exceptions for those sites. See the example for how to do that.
5197 <term>Example usage (sections):</term>
5200 # Selectively turn off compression, and enable a filter
5202 { +filter{tiny-textforms} +prevent-compression }
5203 # Match only these sites
5208 # Or instead, we could set a universal default:
5210 { +prevent-compression }
5213 # Then maybe make exceptions for broken sites:
5215 { -prevent-compression }
5216 .compusa.com/</screen>
5224 <!-- ~~~~~ New section ~~~~~ -->
5225 <sect3 renderas="sect4" id="overwrite-last-modified">
5226 <title>overwrite-last-modified</title>
5232 <term>Typical use:</term>
5234 <para>Prevent yet another way to track the user's steps between sessions.</para>
5239 <term>Effect:</term>
5242 Deletes the <quote>Last-Modified:</quote> HTTP server header or modifies its value.
5249 <!-- Boolean, Parameterized, Multi-value -->
5251 <para>Parameterized.</para>
5256 <term>Parameter:</term>
5259 One of the keywords: <quote>block</quote>, <quote>reset-to-request-time</quote>
5260 and <quote>randomize</quote>
5269 Removing the <quote>Last-Modified:</quote> header is useful for filter
5270 testing, where you want to force a real reload instead of getting status
5271 code <quote>304</quote>, which would cause the browser to reuse the old
5272 version of the page.
5275 The <quote>randomize</quote> option overwrites the value of the
5276 <quote>Last-Modified:</quote> header with a randomly chosen time
5277 between the original value and the current time. In theory the server
5278 could send each document with a different <quote>Last-Modified:</quote>
5279 header to track visits without using cookies. <quote>Randomize</quote>
5280 makes it impossible and the browser can still revalidate cached documents.
5283 <quote>reset-to-request-time</quote> overwrites the value of the
5284 <quote>Last-Modified:</quote> header with the current time. You could use
5285 this option together with
5286 <literal><link linkend="hide-if-modified-since">hide-if-modified-since</link></literal>
5287 to further customize your random range.
5290 The preferred parameter here is <quote>randomize</quote>. It is safe
5291 to use, as long as the time settings are more or less correct.
5292 If the server sets the <quote>Last-Modified:</quote> header to the time
5293 of the request, the random range becomes zero and the value stays the same.
5294 Therefore you should later randomize it a second time with
5295 <literal><link linkend="hide-if-modified-since">hided-if-modified-since</link></literal>,
5299 It is also recommended to use this action together with
5300 <literal><link linkend="crunch-if-none-match">crunch-if-none-match</link></literal>.
5306 <term>Example usage:</term>
5308 <screen># Let the browser revalidate without being tracked across sessions
5309 { +hide-if-modified-since{-60} \
5310 +overwrite-last-modified{randomize} \
5311 +crunch-if-none-match}
5319 <!-- ~~~~~ New section ~~~~~ -->
5320 <sect3 renderas="sect4" id="redirect">
5321 <title>redirect</title>
5327 <term>Typical use:</term>
5330 Redirect requests to other sites.
5336 <term>Effect:</term>
5339 Convinces the browser that the requested document has been moved
5340 to another location and the browser should get it from there.
5347 <!-- Boolean, Parameterized, Multi-value -->
5349 <para>Parameterized</para>
5354 <term>Parameter:</term>
5357 An absolute URL or a single pcrs command.
5366 Requests to which this action applies are answered with a
5367 HTTP redirect to URLs of your choosing. The new URL is
5368 either provided as parameter, or derived by applying a
5369 single pcrs command to the original URL.
5372 The syntax for pcrs commands is documented in the
5373 <link linkend="filter-file">filter file</link> section.
5376 Requests can't be blocked and redirected at the same time,
5377 applying this action together with
5378 <literal><link linkend="block">block</link></literal>
5379 is a configuration error. Currently the request is blocked
5380 and an error message logged, the behavior may change in the
5381 future and result in Privoxy rejecting the action file.
5384 This action can be combined with
5385 <literal><link linkend="fast-redirects">fast-redirects{check-decoded-url}</link></literal>
5386 to redirect to a decoded version of a rewritten URL.
5389 Use this action carefully, make sure not to create redirection loops
5390 and be aware that using your own redirects might make it
5391 possible to fingerprint your requests.
5394 In case of problems with your redirects, or simply to watch
5395 them working, enable <link linkend="DEBUG">debug 128</link>.
5401 <term>Example usages:</term>
5403 <screen># Replace example.com's style sheet with another one
5404 { +redirect{http://localhost/css-replacements/example.com.css} }
5405 example.com/stylesheet\.css
5407 # Create a short, easy to remember nickname for a favorite site
5408 # (relies on the browser to accept and forward invalid URLs to &my-app;)
5409 { +redirect{https://www.privoxy.org/user-manual/actions-file.html} }
5412 # Always use the expanded view for Undeadly.org articles
5413 # (Note the $ at the end of the URL pattern to make sure
5414 # the request for the rewritten URL isn't redirected as well)
5415 {+redirect{s@$@&mode=expanded@}}
5416 undeadly.org/cgi\?action=article&sid=\d*$
5418 # Redirect Google search requests to MSN
5419 {+redirect{s@^http://[^/]*/search\?q=([^&]*).*@http://search.msn.com/results.aspx?q=$1@}}
5422 # Redirect MSN search requests to Yahoo
5423 {+redirect{s@^http://[^/]*/results\.aspx\?q=([^&]*).*@http://search.yahoo.com/search?p=$1@}}
5424 search.msn.com//results\.aspx\?q=
5426 # Redirect http://example.com/&bla=fasel&toChange=foo (and any other value but "bar")
5427 # to http://example.com/&bla=fasel&toChange=bar
5429 # The URL pattern makes sure that the following request isn't redirected again.
5430 {+redirect{s@toChange=[^&]+@toChange=bar@}}
5431 example.com/.*toChange=(?!bar)
5433 # Add a shortcut to look up illumos bugs
5434 {+redirect{s@^http://i([0-9]+)/.*@https://www.illumos.org/issues/$1@}}
5435 # Redirected URL = http://i4974/
5436 # Redirect Destination = https://www.illumos.org/issues/4974
5437 i[0-9][0-9][0-9][0-9]*/
5439 # Redirect remote requests for this manual
5440 # to the local version delivered by Privoxy
5441 {+redirect{s@^http://www@http://config@}}
5442 www.privoxy.org/user-manual/</screen>
5450 <!-- ~~~~~ New section ~~~~~ -->
5451 <sect3 renderas="sect4" id="server-header-filter">
5452 <title>server-header-filter</title>
5456 <term>Typical use:</term>
5459 Rewrite or remove single server headers.
5465 <term>Effect:</term>
5468 All server headers to which this action applies are filtered on-the-fly
5469 through the specified regular expression based substitutions.
5476 <!-- boolean, parameterized, Multi-value -->
5478 <para>Multi-value.</para>
5483 <term>Parameter:</term>
5486 The name of a server-header filter, as defined in one of the
5487 <link linkend="filter-file">filter files</link>.
5496 Server-header filters are applied to each header on its own, not to
5497 all at once. This makes it easier to diagnose problems, but on the downside
5498 you can't write filters that only change header x if header y's value is z.
5499 You can do that by using tags though.
5502 Server-header filters are executed after the other header actions have finished
5503 and use their output as input.
5506 Please refer to the <link linkend="filter-file">filter file chapter</link>
5507 to learn which server-header filters are available by default, and how to
5514 <term>Example usage (section):</term>
5517 {+server-header-filter{html-to-xml}}
5518 example.org/xml-instance-that-is-delivered-as-html
5520 {+server-header-filter{xml-to-html}}
5521 example.org/instance-that-is-delivered-as-xml-but-is-not
5530 <!-- ~~~~~ New section ~~~~~ -->
5531 <sect3 renderas="sect4" id="server-header-tagger">
5532 <title>server-header-tagger</title>
5536 <term>Typical use:</term>
5539 Enable or disable filters based on the Content-Type header.
5545 <term>Effect:</term>
5548 Server headers to which this action applies are filtered on-the-fly through
5549 the specified regular expression based substitutions, the result is used as
5557 <!-- boolean, parameterized, Multi-value -->
5559 <para>Multi-value.</para>
5564 <term>Parameter:</term>
5567 The name of a server-header tagger, as defined in one of the
5568 <link linkend="filter-file">filter files</link>.
5577 Server-header taggers are applied to each header on its own,
5578 and as the header isn't modified, each tagger <quote>sees</quote>
5582 Server-header taggers are executed before all other header actions
5583 that modify server headers. Their tags can be used to control
5584 all of the other server-header actions, the content filters
5585 and the crunch actions (<link linkend="redirect">redirect</link>
5586 and <link linkend="block">block</link>).
5589 Obviously crunching based on tags created by server-header taggers
5590 doesn't prevent the request from showing up in the server's log file.
5597 <term>Example usage (section):</term>
5600 # Tag every request with the content type declared by the server
5601 {+server-header-tagger{content-type}}
5604 # If the response has a tag starting with 'image/' enable an external
5605 # filter that only applies to images.
5607 # Note that the filter is not available by default, it's just a
5608 # <literal><link linkend="external-filter-syntax">silly example</link></literal>.
5609 {+external-filter{rotate-image} +force-text-mode}
5619 <!-- ~~~~~ New section ~~~~~ -->
5620 <sect3 renderas="sect4" id="session-cookies-only">
5621 <title>session-cookies-only</title>
5625 <term>Typical use:</term>
5628 Allow only temporary <quote>session</quote> cookies (for the current
5629 browser session <emphasis>only</emphasis>).
5635 <term>Effect:</term>
5638 Deletes the <quote>expires</quote> field from <quote>Set-Cookie:</quote>
5639 server headers. Most browsers will not store such cookies permanently and
5640 forget them in between sessions.
5647 <!-- Boolean, Parameterized, Multi-value -->
5649 <para>Boolean.</para>
5654 <term>Parameter:</term>
5666 This is less strict than <literal><link linkend="crunch-incoming-cookies">crunch-incoming-cookies</link></literal> /
5667 <literal><link linkend="crunch-outgoing-cookies">crunch-outgoing-cookies</link></literal> and allows you to browse
5668 websites that insist or rely on setting cookies, without compromising your privacy too badly.
5671 Most browsers will not permanently store cookies that have been processed by
5672 <literal>session-cookies-only</literal> and will forget about them between sessions.
5673 This makes profiling cookies useless, but won't break sites which require cookies so
5674 that you can log in for transactions. This is generally turned on for all
5675 sites, and is the recommended setting.
5678 It makes <emphasis>no sense at all</emphasis> to use <literal>session-cookies-only</literal>
5679 together with <literal><link linkend="crunch-incoming-cookies">crunch-incoming-cookies</link></literal> or
5680 <literal><link linkend="crunch-outgoing-cookies">crunch-outgoing-cookies</link></literal>. If you do, cookies
5681 will be plainly killed.
5684 Note that it is up to the browser how it handles such cookies without an <quote>expires</quote>
5685 field. If you use an exotic browser, you might want to try it out to be sure.
5688 This setting also has no effect on cookies that may have been stored
5689 previously by the browser before starting <application>Privoxy</application>.
5690 These would have to be removed manually.
5693 <application>Privoxy</application> also uses
5694 the <link linkend="filter-content-cookies">content-cookies filter</link>
5695 to block some types of cookies. Content cookies are not effected by
5696 <literal>session-cookies-only</literal>.
5702 <term>Example usage:</term>
5704 <screen>+session-cookies-only</screen>
5711 <!-- ~~~~~ New section ~~~~~ -->
5712 <sect3 renderas="sect4" id="set-image-blocker">
5713 <title>set-image-blocker</title>
5717 <term>Typical use:</term>
5719 <para>Choose the replacement for blocked images</para>
5724 <term>Effect:</term>
5727 This action alone doesn't do anything noticeable. If <emphasis>both</emphasis>
5728 <literal><link linkend="block">block</link></literal> <emphasis>and</emphasis> <literal><link
5729 linkend="handle-as-image">handle-as-image</link></literal> <emphasis>also</emphasis>
5730 apply, i.e. if the request is to be blocked as an image,
5731 <emphasis>then</emphasis> the parameter of this action decides what will be
5732 sent as a replacement.
5739 <!-- Boolean, Parameterized, Multi-value -->
5741 <para>Parameterized.</para>
5746 <term>Parameter:</term>
5751 <quote>pattern</quote> to send a built-in checkerboard pattern image. The image is visually
5752 decent, scales very well, and makes it obvious where banners were busted.
5757 <quote>blank</quote> to send a built-in transparent image. This makes banners disappear
5758 completely, but makes it hard to detect where <application>Privoxy</application> has blocked
5759 images on a given page and complicates troubleshooting if <application>Privoxy</application>
5760 has blocked innocent images, like navigation icons.
5765 <quote><replaceable class="parameter">target-url</replaceable></quote> to
5766 send a redirect to <replaceable class="parameter">target-url</replaceable>. You can redirect
5767 to any image anywhere, even in your local filesystem via <quote>file:///</quote> URL.
5768 (But note that not all browsers support redirecting to a local file system).
5771 A good application of redirects is to use special <application>Privoxy</application>-built-in
5772 URLs, which send the built-in images, as <replaceable class="parameter">target-url</replaceable>.
5773 This has the same visual effect as specifying <quote>blank</quote> or <quote>pattern</quote> in
5774 the first place, but enables your browser to cache the replacement image, instead of requesting
5775 it over and over again.
5786 The URLs for the built-in images are <quote>http://config.privoxy.org/send-banner?type=<replaceable
5787 class="parameter">type</replaceable></quote>, where <replaceable class="parameter">type</replaceable> is
5788 either <quote>blank</quote> or <quote>pattern</quote>.
5791 There is a third (advanced) type, called <quote>auto</quote>. It is <emphasis>NOT</emphasis> to be
5792 used in <literal>set-image-blocker</literal>, but meant for use from <link linkend="filter-file">filters</link>.
5793 Auto will select the type of image that would have applied to the referring page, had it been an image.
5799 <term>Example usage:</term>
5804 <screen>+set-image-blocker{pattern}</screen>
5806 Redirect to the BSD daemon:
5808 <screen>+set-image-blocker{http://www.freebsd.org/gifs/dae_up3.gif}</screen>
5810 Redirect to the built-in pattern for better caching:
5812 <screen>+set-image-blocker{http://config.privoxy.org/send-banner?type=pattern}</screen>
5819 <!-- ~~~~~ New section ~~~~~ -->
5820 <sect3 id="summary">
5821 <title>Summary</title>
5823 Note that many of these actions have the potential to cause a page to
5824 misbehave, possibly even not to display at all. There are many ways
5825 a site designer may choose to design his site, and what HTTP header
5826 content, and other criteria, he may depend on. There is no way to have hard
5827 and fast rules for all sites. See the <link
5828 linkend="ACTIONSANAT">Appendix</link> for a brief example on troubleshooting
5834 <!-- ~~~~~ New section ~~~~~ -->
5835 <sect2 id="aliases">
5836 <title>Aliases</title>
5838 Custom <quote>actions</quote>, known to <application>Privoxy</application>
5839 as <quote>aliases</quote>, can be defined by combining other actions.
5840 These can in turn be invoked just like the built-in actions.
5841 Currently, an alias name can contain any character except space, tab,
5843 <quote>{</quote> and <quote>}</quote>, but we <emphasis>strongly
5844 recommend</emphasis> that you only use <quote>a</quote> to <quote>z</quote>,
5845 <quote>0</quote> to <quote>9</quote>, <quote>+</quote>, and <quote>-</quote>.
5846 Alias names are not case sensitive, and are not required to start with a
5847 <quote>+</quote> or <quote>-</quote> sign, since they are merely textually
5851 Aliases can be used throughout the actions file, but they <emphasis>must be
5852 defined in a special section at the top of the file!</emphasis>
5853 And there can only be one such section per actions file. Each actions file may
5854 have its own alias section, and the aliases defined in it are only visible
5858 There are two main reasons to use aliases: One is to save typing for frequently
5859 used combinations of actions, the other one is a gain in flexibility: If you
5860 decide once how you want to handle shops by defining an alias called
5861 <quote>shop</quote>, you can later change your policy on shops in
5862 <emphasis>one</emphasis> place, and your changes will take effect everywhere
5863 in the actions file where the <quote>shop</quote> alias is used. Calling aliases
5864 by their purpose also makes your actions files more readable.
5867 Currently, there is one big drawback to using aliases, though:
5868 <application>Privoxy</application>'s built-in web-based action file
5869 editor honors aliases when reading the actions files, but it expands
5870 them before writing. So the effects of your aliases are of course preserved,
5871 but the aliases themselves are lost when you edit sections that use aliases
5876 Now let's define some aliases...
5880 # Useful custom aliases we can use later.
5882 # Note the (required!) section header line and that this section
5883 # must be at the top of the actions file!
5887 # These aliases just save typing later:
5888 # (Note that some already use other aliases!)
5890 +crunch-all-cookies = +<link linkend="CRUNCH-INCOMING-COOKIES">crunch-incoming-cookies</link> +<link linkend="CRUNCH-OUTGOING-COOKIES">crunch-outgoing-cookies</link>
5891 -crunch-all-cookies = -<link linkend="CRUNCH-INCOMING-COOKIES">crunch-incoming-cookies</link> -<link linkend="CRUNCH-OUTGOING-COOKIES">crunch-outgoing-cookies</link>
5892 +block-as-image = +block{Blocked image.} +handle-as-image
5893 allow-all-cookies = -crunch-all-cookies -<link linkend="SESSION-COOKIES-ONLY">session-cookies-only</link> -<link linkend="FILTER-CONTENT-COOKIES">filter{content-cookies}</link>
5895 # These aliases define combinations of actions
5896 # that are useful for certain types of sites:
5898 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>
5900 shop = -crunch-all-cookies -<link linkend="FILTER-ALL-POPUPS">filter{all-popups}</link>
5902 # Short names for other aliases, for really lazy people ;-)
5904 c0 = +crunch-all-cookies
5905 c1 = -crunch-all-cookies</screen>
5908 ...and put them to use. These sections would appear in the lower part of an
5909 actions file and define exceptions to the default actions (as specified further
5910 up for the <quote>/</quote> pattern):
5914 # These sites are either very complex or very keen on
5915 # user data and require minimal interference to work:
5918 .office.microsoft.com
5919 .windowsupdate.microsoft.com
5920 # Gmail is really mail.google.com, not gmail.com
5924 # Allow cookies (for setting and retrieving your customer data)
5928 .worldpay.com # for quietpc.com
5931 # These shops require pop-ups:
5933 {-filter{all-popups} -filter{unsolicited-popups}}
5935 .overclockers.co.uk</screen>
5938 Aliases like <quote>shop</quote> and <quote>fragile</quote> are typically used for
5939 <quote>problem</quote> sites that require more than one action to be disabled
5940 in order to function properly.
5946 <!-- ~~~~~ New section ~~~~~ -->
5947 <sect2 id="act-examples">
5948 <title>Actions Files Tutorial</title>
5950 The above chapters have shown <link linkend="actions-file">which actions files
5951 there are and how they are organized</link>, how actions are <link
5952 linkend="actions">specified</link> and <link linkend="actions-apply">applied
5953 to URLs</link>, how <link linkend="af-patterns">patterns</link> work, and how to
5954 define and use <link linkend="aliases">aliases</link>. Now, let's look at an
5955 example <filename>match-all.action</filename>, <filename>default.action</filename>
5956 and <filename>user.action</filename> file and see how all these pieces come together:
5959 <sect3 id="match-all">
5960 <title>match-all.action</title>
5962 Remember <emphasis>all actions are disabled when matching starts</emphasis>,
5963 so we have to explicitly enable the ones we want.
5967 While the <filename>match-all.action</filename> file only contains a
5968 single section, it is probably the most important one. It has only one
5969 pattern, <quote><literal>/</literal></quote>, but this pattern
5970 <link linkend="af-patterns">matches all URLs</link>. Therefore, the set of
5971 actions used in this <quote>default</quote> section <emphasis>will
5972 be applied to all requests as a start</emphasis>. It can be partly or
5973 wholly overridden by other actions files like <filename>default.action</filename>
5974 and <filename>user.action</filename>, but it will still be largely responsible
5975 for your overall browsing experience.
5979 Again, at the start of matching, all actions are disabled, so there is
5980 no need to disable any actions here. (Remember: a <quote>+</quote>
5981 preceding the action name enables the action, a <quote>-</quote> disables!).
5982 Also note how this long line has been made more readable by splitting it into
5983 multiple lines with line continuation.
5988 +<link linkend="CHANGE-X-FORWARDED-FOR">change-x-forwarded-for{block}</link> \
5989 +<link linkend="HIDE-FROM-HEADER">hide-from-header{block}</link> \
5990 +<link linkend="SET-IMAGE-BLOCKER">set-image-blocker{pattern}</link> \
5996 The default behavior is now set.
6000 <sect3 id="default-action">
6001 <title>default.action</title>
6004 If you aren't a developer, there's no need for you to edit the
6005 <filename>default.action</filename> file. It is maintained by
6006 the &my-app; developers and if you disagree with some of the
6007 sections, you should overrule them in your <filename>user.action</filename>.
6011 Understanding the <filename>default.action</filename> file can
6012 help you with your <filename>user.action</filename>, though.
6016 The first section in this file is a special section for internal use
6017 that prevents older &my-app; versions from reading the file:
6021 ##########################################################################
6022 # Settings -- Don't change! For internal Privoxy use ONLY.
6023 ##########################################################################
6025 for-privoxy-version=3.0.11</screen>
6028 After that comes the (optional) alias section. We'll use the example
6029 section from the above <link linkend="aliases">chapter on aliases</link>,
6030 that also explains why and how aliases are used:
6034 ##########################################################################
6036 ##########################################################################
6039 # These aliases just save typing later:
6040 # (Note that some already use other aliases!)
6042 +crunch-all-cookies = +<link linkend="CRUNCH-INCOMING-COOKIES">crunch-incoming-cookies</link> +<link linkend="CRUNCH-OUTGOING-COOKIES">crunch-outgoing-cookies</link>
6043 -crunch-all-cookies = -<link linkend="CRUNCH-INCOMING-COOKIES">crunch-incoming-cookies</link> -<link linkend="CRUNCH-OUTGOING-COOKIES">crunch-outgoing-cookies</link>
6044 +block-as-image = +block{Blocked image.} +handle-as-image
6045 mercy-for-cookies = -crunch-all-cookies -<link linkend="SESSION-COOKIES-ONLY">session-cookies-only</link> -<link linkend="FILTER-CONTENT-COOKIES">filter{content-cookies}</link>
6047 # These aliases define combinations of actions
6048 # that are useful for certain types of sites:
6050 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>
6051 shop = -crunch-all-cookies -<link linkend="FILTER-ALL-POPUPS">filter{all-popups}</link></screen>
6054 The first of our specialized sections is concerned with <quote>fragile</quote>
6055 sites, i.e. sites that require minimum interference, because they are either
6056 very complex or very keen on tracking you (and have mechanisms in place that
6057 make them unusable for people who avoid being tracked). We will use
6058 our pre-defined <literal>fragile</literal> alias instead of stating the list
6059 of actions explicitly:
6063 ##########################################################################
6064 # Exceptions for sites that'll break under the default action set:
6065 ##########################################################################
6067 # "Fragile" Use a minimum set of actions for these sites (see alias above):
6070 .office.microsoft.com # surprise, surprise!
6071 .windowsupdate.microsoft.com
6072 mail.google.com</screen>
6075 Shopping sites are not as fragile, but they typically
6076 require cookies to log in, and pop-up windows for shopping
6077 carts or item details. Again, we'll use a pre-defined alias:
6085 .worldpay.com # for quietpc.com
6087 .scan.co.uk</screen>
6090 The <literal><link linkend="FAST-REDIRECTS">fast-redirects</link></literal>
6091 action, which may have been enabled in <filename>match-all.action</filename>,
6092 breaks some sites. So disable it for popular sites where we know it misbehaves:
6096 { -<link linkend="FAST-REDIRECTS">fast-redirects</link> }
6100 .altavista.com/.*(like|url|link):http
6101 .altavista.com/trans.*urltext=http
6102 .nytimes.com</screen>
6105 It is important that <application>Privoxy</application> knows which
6106 URLs belong to images, so that <emphasis>if</emphasis> they are to
6107 be blocked, a substitute image can be sent, rather than an HTML page.
6108 Contacting the remote site to find out is not an option, since it
6109 would destroy the loading time advantage of banner blocking, and it
6110 would feed the advertisers information about you. We can mark any
6111 URL as an image with the <literal><link
6112 linkend="handle-as-image">handle-as-image</link></literal> action,
6113 and marking all URLs that end in a known image file extension is a
6118 ##########################################################################
6120 ##########################################################################
6122 # Define which file types will be treated as images, in case they get
6123 # blocked further down this file:
6125 { +<link linkend="HANDLE-AS-IMAGE">handle-as-image</link> }
6126 /.*\.(gif|jpe?g|png|bmp|ico)$</screen>
6129 And then there are known banner sources. They often use scripts to
6130 generate the banners, so it won't be visible from the URL that the
6131 request is for an image. Hence we block them <emphasis>and</emphasis>
6132 mark them as images in one go, with the help of our
6133 <literal>+block-as-image</literal> alias defined above. (We could of
6134 course just as well use <literal>+<link linkend="block">block</link>
6135 +<link linkend="handle-as-image">handle-as-image</link></literal> here.)
6136 Remember that the type of the replacement image is chosen by the
6137 <literal><link linkend="set-image-blocker">set-image-blocker</link></literal>
6138 action. Since all URLs have matched the default section with its
6139 <literal>+<link linkend="set-image-blocker">set-image-blocker</link>{pattern}</literal>
6140 action before, it still applies and needn't be repeated:
6144 # Known ad generators:
6149 .ad.*.doubleclick.net
6150 .a.yimg.com/(?:(?!/i/).)*$
6151 .a[0-9].yimg.com/(?:(?!/i/).)*$
6156 One of the most important jobs of <application>Privoxy</application>
6157 is to block banners. Many of these can be <quote>blocked</quote>
6158 by the <literal><link linkend="filter">filter</link>{banners-by-size}</literal>
6159 action, which we enabled above, and which deletes the references to banner
6160 images from the pages while they are loaded, so the browser doesn't request
6161 them anymore, and hence they don't need to be blocked here. But this naturally
6162 doesn't catch all banners, and some people choose not to use filters, so we
6163 need a comprehensive list of patterns for banner URLs here, and apply the
6164 <literal><link linkend="block">block</link></literal> action to them.
6167 First comes many generic patterns, which do most of the work, by
6168 matching typical domain and path name components of banners. Then comes
6169 a list of individual patterns for specific sites, which is omitted here
6170 to keep the example short:
6174 ##########################################################################
6175 # Block these fine banners:
6176 ##########################################################################
6177 { <link linkend="BLOCK">+block{Banner ads.}</link> }
6185 /.*count(er)?\.(pl|cgi|exe|dll|asp|php[34]?)
6186 /(?:.*/)?(publicite|werbung|rekla(ma|me|am)|annonse|maino(kset|nta|s)?)/
6188 # Site-specific patterns (abbreviated):
6190 .hitbox.com</screen>
6193 It's quite remarkable how many advertisers actually call their banner
6194 servers ads.<replaceable>company</replaceable>.com, or call the directory
6195 in which the banners are stored literally <quote>banners</quote>. So the above
6196 generic patterns are surprisingly effective.
6199 But being very generic, they necessarily also catch URLs that we don't want
6200 to block. The pattern <literal>.*ads.</literal> e.g. catches
6201 <quote>nasty-<emphasis>ads</emphasis>.nasty-corp.com</quote> as intended,
6202 but also <quote>downlo<emphasis>ads</emphasis>.sourcefroge.net</quote> or
6203 <quote><emphasis>ads</emphasis>l.some-provider.net.</quote> So here come some
6204 well-known exceptions to the <literal>+<link linkend="BLOCK">block</link></literal>
6208 Note that these are exceptions to exceptions from the default! Consider the URL
6209 <quote>downloads.sourcefroge.net</quote>: Initially, all actions are deactivated,
6210 so it wouldn't get blocked. Then comes the defaults section, which matches the
6211 URL, but just deactivates the <literal><link linkend="BLOCK">block</link></literal>
6212 action once again. Then it matches <literal>.*ads.</literal>, an exception to the
6213 general non-blocking policy, and suddenly
6214 <literal><link linkend="BLOCK">+block</link></literal> applies. And now, it'll match
6215 <literal>.*loads.</literal>, where <literal><link linkend="BLOCK">-block</link></literal>
6216 applies, so (unless it matches <emphasis>again</emphasis> further down) it ends up
6217 with no <literal><link linkend="BLOCK">block</link></literal> action applying.
6221 ##########################################################################
6222 # Save some innocent victims of the above generic block patterns:
6223 ##########################################################################
6227 { -<link linkend="BLOCK">block</link> }
6228 adv[io]*. # (for advogato.org and advice.*)
6229 adsl. # (has nothing to do with ads)
6230 adobe. # (has nothing to do with ads either)
6231 ad[ud]*. # (adult.* and add.*)
6232 .edu # (universities don't host banners (yet!))
6233 .*loads. # (downloads, uploads etc)
6241 www.globalintersec.com/adv # (adv = advanced)
6242 www.ugu.com/sui/ugu/adv</screen>
6245 Filtering source code can have nasty side effects,
6246 so make an exception for our friends at sourceforge.net,
6247 and all paths with <quote>cvs</quote> in them. Note that
6248 <literal>-<link linkend="FILTER">filter</link></literal>
6249 disables <emphasis>all</emphasis> filters in one fell swoop!
6253 # Don't filter code!
6255 { -<link linkend="FILTER">filter</link> }
6260 .sourceforge.net</screen>
6263 The actual <filename>default.action</filename> is of course much more
6264 comprehensive, but we hope this example made clear how it works.
6269 <sect3 id="user-action"><title>user.action</title>
6272 So far we are painting with a broad brush by setting general policies,
6273 which would be a reasonable starting point for many people. Now,
6274 you might want to be more specific and have customized rules that
6275 are more suitable to your personal habits and preferences. These would
6276 be for narrowly defined situations like your ISP or your bank, and should
6277 be placed in <filename>user.action</filename>, which is parsed after all other
6278 actions files and hence has the last word, over-riding any previously
6279 defined actions. <filename>user.action</filename> is also a
6280 <emphasis>safe</emphasis> place for your personal settings, since
6281 <filename>default.action</filename> is actively maintained by the
6282 <application>Privoxy</application> developers and you'll probably want
6283 to install updated versions from time to time.
6287 So let's look at a few examples of things that one might typically do in
6288 <filename>user.action</filename>:
6292 <!-- brief sample user.action here -->
6295 # My user.action file. <fred@example.com></screen>
6298 As <link linkend="aliases">aliases</link> are local to the actions
6299 file that they are defined in, you can't use the ones from
6300 <filename>default.action</filename>, unless you repeat them here:
6304 # Aliases are local to the file they are defined in.
6305 # (Re-)define aliases for this file:
6309 # These aliases just save typing later, and the alias names should
6310 # be self explanatory.
6312 +crunch-all-cookies = +crunch-incoming-cookies +crunch-outgoing-cookies
6313 -crunch-all-cookies = -crunch-incoming-cookies -crunch-outgoing-cookies
6314 allow-all-cookies = -crunch-all-cookies -session-cookies-only
6315 allow-popups = -filter{all-popups}
6316 +block-as-image = +block{Blocked as image.} +handle-as-image
6317 -block-as-image = -block
6319 # These aliases define combinations of actions that are useful for
6320 # certain types of sites:
6322 fragile = -block -crunch-all-cookies -filter -fast-redirects -hide-referrer
6323 shop = -crunch-all-cookies allow-popups
6325 # Allow ads for selected useful free sites:
6327 allow-ads = -block -filter{banners-by-size} -filter{banners-by-link}
6329 # Alias for specific file types that are text, but might have conflicting
6330 # MIME types. We want the browser to force these to be text documents.
6331 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>
6334 Say you have accounts on some sites that you visit regularly, and
6335 you don't want to have to log in manually each time. So you'd like
6336 to allow persistent cookies for these sites. The
6337 <literal>allow-all-cookies</literal> alias defined above does exactly
6338 that, i.e. it disables crunching of cookies in any direction, and the
6339 processing of cookies to make them only temporary.
6343 { allow-all-cookies }
6347 .redhat.com</screen>
6350 Your bank is allergic to some filter, but you don't know which, so you disable them all:
6354 { -<link linkend="FILTER">filter</link> }
6355 .your-home-banking-site.com</screen>
6358 Some file types you may not want to filter for various reasons:
6362 # Technical documentation is likely to contain strings that might
6363 # erroneously get altered by the JavaScript-oriented filters:
6368 # And this stupid host sends streaming video with a wrong MIME type,
6369 # so that Privoxy thinks it is getting HTML and starts filtering:
6371 stupid-server.example.com/</screen>
6374 Example of a simple <link linkend="BLOCK">block</link> action. Say you've
6375 seen an ad on your favourite page on example.com that you want to get rid of.
6376 You have right-clicked the image, selected <quote>copy image location</quote>
6377 and pasted the URL below while removing the leading http://, into a
6378 <literal>{ +block{} }</literal> section. Note that <literal>{ +handle-as-image
6379 }</literal> need not be specified, since all URLs ending in
6380 <literal>.gif</literal> will be tagged as images by the general rules as set
6381 in default.action anyway:
6385 { +<link linkend="BLOCK">block</link>{Nasty ads.} }
6386 www.example.com/nasty-ads/sponsor\.gif
6387 another.example.net/more/junk/here/</screen>
6390 The URLs of dynamically generated banners, especially from large banner
6391 farms, often don't use the well-known image file name extensions, which
6392 makes it impossible for <application>Privoxy</application> to guess
6393 the file type just by looking at the URL.
6394 You can use the <literal>+block-as-image</literal> alias defined above for
6396 Note that objects which match this rule but then turn out NOT to be an
6397 image are typically rendered as a <quote>broken image</quote> icon by the
6398 browser. Use cautiously.
6406 ar.atwola.com/</screen>
6409 Now you noticed that the default configuration breaks Forbes Magazine,
6410 but you were too lazy to find out which action is the culprit, and you
6411 were again too lazy to give <link linkend="contact">feedback</link>, so
6412 you just used the <literal>fragile</literal> alias on the site, and
6413 -- <emphasis>whoa!</emphasis> -- it worked. The <literal>fragile</literal>
6414 aliases disables those actions that are most likely to break a site. Also,
6415 good for testing purposes to see if it is <application>Privoxy</application>
6416 that is causing the problem or not. We later find other regular sites
6417 that misbehave, and add those to our personalized list of troublemakers:
6424 .mybank.com</screen>
6427 You like the <quote>fun</quote> text replacements in <filename>default.filter</filename>,
6428 but it is disabled in the distributed actions file.
6429 So you'd like to turn it on in your private,
6430 update-safe config, once and for all:
6434 { +<link linkend="filter-fun">filter{fun}</link> }
6435 / # For ALL sites!</screen>
6438 Note that the above is not really a good idea: There are exceptions
6439 to the filters in <filename>default.action</filename> for things that
6440 really shouldn't be filtered, like code on CVS->Web interfaces. Since
6441 <filename>user.action</filename> has the last word, these exceptions
6442 won't be valid for the <quote>fun</quote> filtering specified here.
6446 You might also worry about how your favourite free websites are
6447 funded, and find that they rely on displaying banner advertisements
6448 to survive. So you might want to specifically allow banners for those
6449 sites that you feel provide value to you:
6459 Note that <literal>allow-ads</literal> has been aliased to
6460 <literal>-<link linkend="block">block</link></literal>,
6461 <literal>-<link linkend="filter-banners-by-size">filter{banners-by-size}</link></literal>, and
6462 <literal>-<link linkend="filter-banners-by-link">filter{banners-by-link}</link></literal> above.
6466 Invoke another alias here to force an over-ride of the MIME type <literal>
6467 application/x-sh</literal> which typically would open a download type
6468 dialog. In my case, I want to look at the shell script, and then I can save
6469 it should I choose to.
6477 <filename>user.action</filename> is generally the best place to define
6478 exceptions and additions to the default policies of
6479 <filename>default.action</filename>. Some actions are safe to have their
6480 default policies set here though. So let's set a default policy to have a
6481 <quote>blank</quote> image as opposed to the checkerboard pattern for
6482 <emphasis>ALL</emphasis> sites. <quote>/</quote> of course matches all URL
6487 { +<link linkend="set-image-blocker">set-image-blocker{blank}</link> }
6488 / # ALL sites</screen>
6493 <!-- ~ End section ~ -->
6497 <!-- ~ End section ~ -->
6499 <!-- ~~~~~~~~ New section Header ~~~~~~~~~ -->
6501 <sect1 id="filter-file">
6502 <title>Filter Files</title>
6505 On-the-fly text substitutions need
6506 to be defined in a <quote>filter file</quote>. Once defined, they
6507 can then be invoked as an <quote>action</quote>.
6511 &my-app; supports three different pcrs-based filter actions:
6512 <literal><link linkend="filter">filter</link></literal> to
6513 rewrite the content that is send to the client,
6514 <literal><link linkend="client-header-filter">client-header-filter</link></literal>
6515 to rewrite headers that are send by the client, and
6516 <literal><link linkend="server-header-filter">server-header-filter</link></literal>
6517 to rewrite headers that are send by the server.
6521 &my-app; also supports two tagger actions:
6522 <literal><link linkend="client-header-tagger">client-header-tagger</link></literal>
6524 <literal><link linkend="server-header-tagger">server-header-tagger</link></literal>.
6525 Taggers and filters use the same syntax in the filter files, the difference
6526 is that taggers don't modify the text they are filtering, but use a rewritten
6527 version of the filtered text as tag. The tags can then be used to change the
6528 applying actions through sections with <link linkend="tag-pattern">tag-patterns</link>.
6532 Finally &my-app; supports the
6533 <literal><link linkend="external-filter">external-filter</link></literal> action
6534 to enable <literal><link linkend="external-filter-syntax">external filters</link></literal>
6535 written in proper programming languages.
6540 Multiple filter files can be defined through the <literal> <link
6541 linkend="filterfile">filterfile</link></literal> config directive. The filters
6542 as supplied by the developers are located in
6543 <filename>default.filter</filename>. It is recommended that any locally
6544 defined or modified filters go in a separately defined file such as
6545 <filename>user.filter</filename>.
6549 Common tasks for content filters are to eliminate common annoyances in
6550 HTML and JavaScript, such as pop-up windows,
6551 exit consoles, crippled windows without navigation tools, the
6552 infamous <BLINK> tag etc, to suppress images with certain
6553 width and height attributes (standard banner sizes or web-bugs),
6554 or just to have fun.
6558 Enabled content filters are applied to any content whose
6559 <quote>Content Type</quote> header is recognised as a sign
6560 of text-based content, with the exception of <literal>text/plain</literal>.
6561 Use the <link linkend="FORCE-TEXT-MODE">force-text-mode</link> action
6562 to also filter other content.
6566 Substitutions are made at the source level, so if you want to <quote>roll
6567 your own</quote> filters, you should first be familiar with HTML syntax,
6568 and, of course, regular expressions.
6572 Just like the <link linkend="actions-file">actions files</link>, the
6573 filter file is organized in sections, which are called <emphasis>filters</emphasis>
6574 here. Each filter consists of a heading line, that starts with one of the
6575 <emphasis>keywords</emphasis> <literal>FILTER:</literal>,
6576 <literal>CLIENT-HEADER-FILTER:</literal> or <literal>SERVER-HEADER-FILTER:</literal>
6577 followed by the filter's <emphasis>name</emphasis>, and a short (one line)
6578 <emphasis>description</emphasis> of what it does. Below that line
6579 come the <emphasis>jobs</emphasis>, i.e. lines that define the actual
6580 text substitutions. By convention, the name of a filter
6581 should describe what the filter <emphasis>eliminates</emphasis>. The
6582 comment is used in the <ulink url="http://config.privoxy.org/">web-based
6583 user interface</ulink>.
6587 Once a filter called <replaceable>name</replaceable> has been defined
6588 in the filter file, it can be invoked by using an action of the form
6589 +<literal><link linkend="filter">filter</link>{<replaceable>name</replaceable>}</literal>
6590 in any <link linkend="actions-file">actions file</link>.
6594 Filter definitions start with a header line that contains the filter
6595 type, the filter name and the filter description.
6596 A content filter header line for a filter called <quote>foo</quote> could look
6600 <screen>FILTER: foo Replace all "foo" with "bar"</screen>
6603 Below that line, and up to the next header line, come the jobs that
6604 define what text replacements the filter executes. They are specified
6605 in a syntax that imitates <ulink url="http://www.perl.org/">Perl</ulink>'s
6606 <literal>s///</literal> operator. If you are familiar with Perl, you
6607 will find this to be quite intuitive, and may want to look at the
6608 PCRS documentation for the subtle differences to Perl behaviour.
6612 Most notably, the non-standard option letter <literal>U</literal> is supported,
6613 which turns the default to ungreedy matching (add <literal>?</literal> to
6614 quantifiers to turn them greedy again).
6618 The non-standard option letter <literal>D</literal> (dynamic) allows
6619 to use the variables $host, $origin (the IP address the request came from),
6620 $path, $url and $listen-address (the address on which Privoxy accepted the
6621 client request. Example: 127.0.0.1:8118).
6622 They will be replaced with the value they refer to before the filter
6627 Note that '$' is a bad choice for a delimiter in a dynamic filter as you
6628 might end up with unintended variables if you use a variable name
6629 directly after the delimiter. Variables will be resolved without
6630 escaping anything, therefore you also have to be careful not to chose
6631 delimiters that appear in the replacement text. For example '<' should
6632 be save, while '?' will sooner or later cause conflicts with $url.
6636 The non-standard option letter <literal>T</literal> (trivial) prevents
6637 parsing for backreferences in the substitute. Use it if you want to include
6638 text like '$&' in your substitute without quoting.
6643 <ulink url="http://en.wikipedia.org/wiki/Regular_expressions"><quote>Regular
6644 Expressions</quote></ulink>, you might want to take a look at
6645 the <link linkend="regex">Appendix on regular expressions</link>, and
6646 see the <ulink url="http://perldoc.perl.org/perlre.html">Perl
6648 <ulink url="http://perldoc.perl.org/perlop.html">the
6649 <literal>s///</literal> operator's syntax</ulink> and <ulink
6650 url="http://perldoc.perl.org/perlre.html">Perl-style regular
6651 expressions</ulink> in general.
6652 The below examples might also help to get you started.
6656 <!-- ~~~~~~~~ New section Header ~~~~~~~~~ -->
6658 <sect2 id="filter-file-tut"><title>Filter File Tutorial</title>
6660 Now, let's complete our <quote>foo</quote> content filter. We have already defined
6661 the heading, but the jobs are still missing. Since all it does is to replace
6662 <quote>foo</quote> with <quote>bar</quote>, there is only one (trivial) job
6666 <screen>s/foo/bar/</screen>
6669 But wait! Didn't the comment say that <emphasis>all</emphasis> occurrences
6670 of <quote>foo</quote> should be replaced? Our current job will only take
6671 care of the first <quote>foo</quote> on each page. For global substitution,
6672 we'll need to add the <literal>g</literal> option:
6675 <screen>s/foo/bar/g</screen>
6678 Our complete filter now looks like this:
6681 <screen>FILTER: foo Replace all "foo" with "bar"
6682 s/foo/bar/g</screen>
6685 Let's look at some real filters for more interesting examples. Here you see
6686 a filter that protects against some common annoyances that arise from JavaScript
6687 abuse. Let's look at its jobs one after the other:
6692 FILTER: js-annoyances Get rid of particularly annoying JavaScript abuse
6694 # Get rid of JavaScript referrer tracking. Test page: http://www.randomoddness.com/untitled.htm
6696 s|(<script.*)document\.referrer(.*</script>)|$1"Not Your Business!"$2|Usg</screen>
6699 Following the header line and a comment, you see the job. Note that it uses
6700 <literal>|</literal> as the delimiter instead of <literal>/</literal>, because
6701 the pattern contains a forward slash, which would otherwise have to be escaped
6702 by a backslash (<literal>\</literal>).
6706 Now, let's examine the pattern: it starts with the text <literal><script.*</literal>
6707 enclosed in parentheses. Since the dot matches any character, and <literal>*</literal>
6708 means: <quote>Match an arbitrary number of the element left of myself</quote>, this
6709 matches <quote><script</quote>, followed by <emphasis>any</emphasis> text, i.e.
6710 it matches the whole page, from the start of the first <script> tag.
6714 That's more than we want, but the pattern continues: <literal>document\.referrer</literal>
6715 matches only the exact string <quote>document.referrer</quote>. The dot needed to
6716 be <emphasis>escaped</emphasis>, i.e. preceded by a backslash, to take away its
6717 special meaning as a joker, and make it just a regular dot. So far, the meaning is:
6718 Match from the start of the first <script> tag in a the page, up to, and including,
6719 the text <quote>document.referrer</quote>, if <emphasis>both</emphasis> are present
6720 in the page (and appear in that order).
6724 But there's still more pattern to go. The next element, again enclosed in parentheses,
6725 is <literal>.*</script></literal>. You already know what <literal>.*</literal>
6726 means, so the whole pattern translates to: Match from the start of the first <script>
6727 tag in a page to the end of the last <script> tag, provided that the text
6728 <quote>document.referrer</quote> appears somewhere in between.
6732 This is still not the whole story, since we have ignored the options and the parentheses:
6733 The portions of the page matched by sub-patterns that are enclosed in parentheses, will be
6734 remembered and be available through the variables <literal>$1, $2, ...</literal> in
6735 the substitute. The <literal>U</literal> option switches to ungreedy matching, which means
6736 that the first <literal>.*</literal> in the pattern will only <quote>eat up</quote> all
6737 text in between <quote><script</quote> and the <emphasis>first</emphasis> occurrence
6738 of <quote>document.referrer</quote>, and that the second <literal>.*</literal> will
6739 only span the text up to the <emphasis>first</emphasis> <quote></script></quote>
6740 tag. Furthermore, the <literal>s</literal> option says that the match may span
6741 multiple lines in the page, and the <literal>g</literal> option again means that the
6742 substitution is global.
6746 So, to summarize, the pattern means: Match all scripts that contain the text
6747 <quote>document.referrer</quote>. Remember the parts of the script from
6748 (and including) the start tag up to (and excluding) the string
6749 <quote>document.referrer</quote> as <literal>$1</literal>, and the part following
6750 that string, up to and including the closing tag, as <literal>$2</literal>.
6754 Now the pattern is deciphered, but wasn't this about substituting things? So
6755 lets look at the substitute: <literal>$1"Not Your Business!"$2</literal> is
6756 easy to read: The text remembered as <literal>$1</literal>, followed by
6757 <literal>"Not Your Business!"</literal> (<emphasis>including</emphasis>
6758 the quotation marks!), followed by the text remembered as <literal>$2</literal>.
6759 This produces an exact copy of the original string, with the middle part
6760 (the <quote>document.referrer</quote>) replaced by <literal>"Not Your
6761 Business!"</literal>.
6765 The whole job now reads: Replace <quote>document.referrer</quote> by
6766 <literal>"Not Your Business!"</literal> wherever it appears inside a
6767 <script> tag. Note that this job won't break JavaScript syntax,
6768 since both the original and the replacement are syntactically valid
6769 string objects. The script just won't have access to the referrer
6770 information anymore.
6774 We'll show you two other jobs from the JavaScript taming department, but
6775 this time only point out the constructs of special interest:
6779 # The status bar is for displaying link targets, not pointless blahblah
6781 s/window\.status\s*=\s*(['"]).*?\1/dUmMy=1/ig</screen>
6784 <literal>\s</literal> stands for whitespace characters (space, tab, newline,
6785 carriage return, form feed), so that <literal>\s*</literal> means: <quote>zero
6786 or more whitespace</quote>. The <literal>?</literal> in <literal>.*?</literal>
6787 makes this matching of arbitrary text ungreedy. (Note that the <literal>U</literal>
6788 option is not set). The <literal>['"]</literal> construct means: <quote>a single
6789 <emphasis>or</emphasis> a double quote</quote>. Finally, <literal>\1</literal> is
6790 a back-reference to the first parenthesis just like <literal>$1</literal> above,
6791 with the difference that in the <emphasis>pattern</emphasis>, a backslash indicates
6792 a back-reference, whereas in the <emphasis>substitute</emphasis>, it's the dollar.
6796 So what does this job do? It replaces assignments of single- or double-quoted
6797 strings to the <quote>window.status</quote> object with a dummy assignment
6798 (using a variable name that is hopefully odd enough not to conflict with
6799 real variables in scripts). Thus, it catches many cases where e.g. pointless
6800 descriptions are displayed in the status bar instead of the link target when
6801 you move your mouse over links.
6805 # Kill OnUnload popups. Yummy. Test: http://www.zdnet.com/zdsubs/yahoo/tree/yfs.html
6807 s/(<body [^>]*)onunload(.*>)/$1never$2/iU</screen>
6811 <ulink url="http://www.w3.org/TR/2000/REC-DOM-Level-2-Events-20001113/events.html#Events-eventgroupings-htmlevents">OnUnload
6812 event binding</ulink> in the HTML DOM was a <emphasis>CRIME</emphasis>.
6813 When I close a browser window, I want it to close and die. Basta.
6814 This job replaces the <quote>onunload</quote> attribute in
6815 <quote><body></quote> tags with the dummy word <literal>never</literal>.
6816 Note that the <literal>i</literal> option makes the pattern matching
6817 case-insensitive. Also note that ungreedy matching alone doesn't always guarantee
6818 a minimal match: In the first parenthesis, we had to use <literal>[^>]*</literal>
6819 instead of <literal>.*</literal> to prevent the match from exceeding the
6820 <body> tag if it doesn't contain <quote>OnUnload</quote>, but the page's
6825 The last example is from the fun department:
6829 FILTER: fun Fun text replacements
6831 # Spice the daily news:
6833 s/microsoft(?!\.com)/MicroSuck/ig</screen>
6836 Note the <literal>(?!\.com)</literal> part (a so-called negative lookahead)
6837 in the job's pattern, which means: Don't match, if the string
6838 <quote>.com</quote> appears directly following <quote>microsoft</quote>
6839 in the page. This prevents links to microsoft.com from being trashed, while
6840 still replacing the word everywhere else.
6844 # Buzzword Bingo (example for extended regex syntax)
6846 s* industry[ -]leading \
6848 | customer[ -]focused \
6849 | market[ -]driven \
6850 | award[ -]winning # Comments are OK, too! \
6851 | high[ -]performance \
6852 | solutions[ -]based \
6856 *<font color="red"><b>BINGO!</b></font> \
6860 The <literal>x</literal> option in this job turns on extended syntax, and allows for
6861 e.g. the liberal use of (non-interpreted!) whitespace for nicer formatting.
6869 <!-- ~~~~~~~~ New section Header ~~~~~~~~~ -->
6871 <sect2 id="predefined-filters"><title>The Pre-defined Filters</title>
6875 Note each filter is also listed in the +filter action section above. Please
6876 keep these listings in sync.
6881 The distribution <filename>default.filter</filename> file contains a selection of
6882 pre-defined filters for your convenience:
6887 <term><emphasis>js-annoyances</emphasis></term>
6890 The purpose of this filter is to get rid of particularly annoying JavaScript abuse.
6896 replaces JavaScript references to the browser's referrer information
6897 with the string "Not Your Business!". This compliments the <literal><link
6898 linkend="hide-referrer">hide-referrer</link></literal> action on the content level.
6903 removes the bindings to the DOM's
6904 <ulink url="http://www.w3.org/TR/2000/REC-DOM-Level-2-Events-20001113/events.html#Events-eventgroupings-htmlevents">unload
6905 event</ulink> which we feel has no right to exist and is responsible for most <quote>exit consoles</quote>, i.e.
6906 nasty windows that pop up when you close another one.
6911 removes code that causes new windows to be opened with undesired properties, such as being
6912 full-screen, non-resizeable, without location, status or menu bar etc.
6917 Use with caution. This is an aggressive filter, and can break sites that
6918 rely heavily on JavaScript.
6924 <term><emphasis>js-events</emphasis></term>
6927 This is a very radical measure. It removes virtually all JavaScript event bindings, which
6928 means that scripts can not react to user actions such as mouse movements or clicks, window
6929 resizing etc, anymore. Use with caution!
6932 We <emphasis>strongly discourage</emphasis> using this filter as a default since it breaks
6933 many legitimate scripts. It is meant for use only on extra-nasty sites (should you really
6940 <term><emphasis>html-annoyances</emphasis></term>
6943 This filter will undo many common instances of HTML based abuse.
6946 The <literal>BLINK</literal> and <literal>MARQUEE</literal> tags
6947 are neutralized (yeah baby!), and browser windows will be created as
6948 resizeable (as of course they should be!), and will have location,
6949 scroll and menu bars -- even if specified otherwise.
6955 <term><emphasis>content-cookies</emphasis></term>
6958 Most cookies are set in the HTTP dialog, where they can be intercepted
6960 <literal><link linkend="crunch-incoming-cookies">crunch-incoming-cookies</link></literal>
6961 and <literal><link linkend="crunch-outgoing-cookies">crunch-outgoing-cookies</link></literal>
6962 actions. But web sites increasingly make use of HTML meta tags and JavaScript
6963 to sneak cookies to the browser on the content level.
6966 This filter disables most HTML and JavaScript code that reads or sets
6967 cookies. It cannot detect all clever uses of these types of code, so it
6968 should not be relied on as an absolute fix. Use it wherever you would also
6969 use the cookie crunch actions.
6975 <term><emphasis>refresh-tags</emphasis></term>
6978 Disable any refresh tags if the interval is greater than nine seconds (so
6979 that redirections done via refresh tags are not destroyed). This is useful
6980 for dial-on-demand setups, or for those who find this HTML feature
6987 <term><emphasis>unsolicited-popups</emphasis></term>
6990 This filter attempts to prevent only <quote>unsolicited</quote> pop-up
6991 windows from opening, yet still allow pop-up windows that the user
6992 has explicitly chosen to open. It was added in version 3.0.1,
6993 as an improvement over earlier such filters.
6996 Technical note: The filter works by redefining the window.open JavaScript
6997 function to a dummy function, <literal>PrivoxyWindowOpen()</literal>,
6998 during the loading and rendering phase of each HTML page access, and
6999 restoring the function afterward.
7002 This is recommended only for browsers that cannot perform this function
7003 reliably themselves. And be aware that some sites require such windows
7004 in order to function normally. Use with caution.
7010 <term><emphasis>all-popups</emphasis></term>
7013 Attempt to prevent <emphasis>all</emphasis> pop-up windows from opening.
7014 Note this should be used with even more discretion than the above, since
7015 it is more likely to break some sites that require pop-ups for normal
7016 usage. Use with caution.
7022 <term><emphasis>img-reorder</emphasis></term>
7025 This is a helper filter that has no value if used alone. It makes the
7026 <literal>banners-by-size</literal> and <literal>banners-by-link</literal>
7027 (see below) filters more effective and should be enabled together with them.
7033 <term><emphasis>banners-by-size</emphasis></term>
7036 This filter removes image tags purely based on what size they are. Fortunately
7037 for us, many ads and banner images tend to conform to certain standardized
7038 sizes, which makes this filter quite effective for ad stripping purposes.
7041 Occasionally this filter will cause false positives on images that are not ads,
7042 but just happen to be of one of the standard banner sizes.
7045 Recommended only for those who require extreme ad blocking. The default
7046 block rules should catch 95+% of all ads <emphasis>without</emphasis> this filter enabled.
7052 <term><emphasis>banners-by-link</emphasis></term>
7055 This is an experimental filter that attempts to kill any banners if
7056 their URLs seem to point to known or suspected click trackers. It is currently
7057 not of much value and is not recommended for use by default.
7063 <term><emphasis>webbugs</emphasis></term>
7066 Webbugs are small, invisible images (technically 1X1 GIF images), that
7067 are used to track users across websites, and collect information on them.
7068 As an HTML page is loaded by the browser, an embedded image tag causes the
7069 browser to contact a third-party site, disclosing the tracking information
7070 through the requested URL and/or cookies for that third-party domain, without
7071 the user ever becoming aware of the interaction with the third-party site.
7072 HTML-ized spam also uses a similar technique to verify email addresses.
7075 This filter removes the HTML code that loads such <quote>webbugs</quote>.
7081 <term><emphasis>tiny-textforms</emphasis></term>
7084 A rather special-purpose filter that can be used to enlarge textareas (those
7085 multi-line text boxes in web forms) and turn off hard word wrap in them.
7086 It was written for the sourceforge.net tracker system where such boxes are
7087 a nuisance, but it can be handy on other sites, too.
7090 It is not recommended to use this filter as a default.
7096 <term><emphasis>jumping-windows</emphasis></term>
7099 Many consider windows that move, or resize themselves to be abusive. This filter
7100 neutralizes the related JavaScript code. Note that some sites might not display
7101 or behave as intended when using this filter. Use with caution.
7107 <term><emphasis>frameset-borders</emphasis></term>
7110 Some web designers seem to assume that everyone in the world will view their
7111 web sites using the same browser brand and version, screen resolution etc,
7112 because only that assumption could explain why they'd use static frame sizes,
7113 yet prevent their frames from being resized by the user, should they be too
7114 small to show their whole content.
7117 This filter removes the related HTML code. It should only be applied to sites
7124 <term><emphasis>demoronizer</emphasis></term>
7127 Many Microsoft products that generate HTML use non-standard extensions (read:
7128 violations) of the ISO 8859-1 aka Latin-1 character set. This can cause those
7129 HTML documents to display with errors on standard-compliant platforms.
7132 This filter translates the MS-only characters into Latin-1 equivalents.
7133 It is not necessary when using MS products, and will cause corruption of
7134 all documents that use 8-bit character sets other than Latin-1. It's mostly
7135 worthwhile for Europeans on non-MS platforms, if weird garbage characters
7136 sometimes appear on some pages, or user agents that don't correct for this on
7139 My version of Mozilla (ancient) shows litte square boxes for quote
7140 characters, and apostrophes on moronized pages. So many pages have this, I
7141 can read them fine now. HB 08/27/06
7148 <term><emphasis>shockwave-flash</emphasis></term>
7151 A filter for shockwave haters. As the name suggests, this filter strips code
7152 out of web pages that is used to embed shockwave flash objects.
7160 <term><emphasis>quicktime-kioskmode</emphasis></term>
7163 Change HTML code that embeds Quicktime objects so that kioskmode, which
7164 prevents saving, is disabled.
7170 <term><emphasis>fun</emphasis></term>
7173 Text replacements for subversive browsing fun. Make fun of your favorite
7174 Monopolist or play buzzword bingo.
7180 <term><emphasis>crude-parental</emphasis></term>
7183 A demonstration-only filter that shows how <application>Privoxy</application>
7184 can be used to delete web content on a keyword basis.
7190 <term><emphasis>ie-exploits</emphasis></term>
7193 An experimental collection of text replacements to disable malicious HTML and JavaScript
7194 code that exploits known security holes in Internet Explorer.
7197 Presently, it only protects against Nimda and a cross-site scripting bug, and
7198 would need active maintenance to provide more substantial protection.
7204 <term><emphasis>site-specifics</emphasis></term>
7207 Some web sites have very specific problems, the cure for which doesn't apply
7208 anywhere else, or could even cause damage on other sites.
7211 This is a collection of such site-specific cures which should only be applied
7212 to the sites they were intended for, which is what the supplied
7213 <filename>default.action</filename> file does. Users shouldn't need to change
7214 anything regarding this filter.
7220 <term><emphasis>google</emphasis></term>
7223 A CSS based block for Google text ads. Also removes a width limitation
7224 and the toolbar advertisement.
7230 <term><emphasis>yahoo</emphasis></term>
7233 Another CSS based block, this time for Yahoo text ads. And removes
7234 a width limitation as well.
7240 <term><emphasis>msn</emphasis></term>
7243 Another CSS based block, this time for MSN text ads. And removes
7244 tracking URLs, as well as a width limitation.
7250 <term><emphasis>blogspot</emphasis></term>
7253 Cleans up some Blogspot blogs. Read the fine print before using this one!
7256 This filter also intentionally removes some navigation stuff and sets the
7257 page width to 100%. As a result, some rounded <quote>corners</quote> would
7258 appear to early or not at all and as fixing this would require a browser
7259 that understands background-size (CSS3), they are removed instead.
7265 <term><emphasis>xml-to-html</emphasis></term>
7268 Server-header filter to change the Content-Type from xml to html.
7274 <term><emphasis>html-to-xml</emphasis></term>
7277 Server-header filter to change the Content-Type from html to xml.
7283 <term><emphasis>no-ping</emphasis></term>
7286 Removes the non-standard <literal>ping</literal> attribute from
7287 anchor and area HTML tags.
7293 <term><emphasis>hide-tor-exit-notation</emphasis></term>
7296 Client-header filter to remove the <command>Tor</command> exit node notation
7297 found in Host and Referer headers.
7300 If &my-app; and <command>Tor</command> are chained and &my-app;
7301 is configured to use socks4a, one can use <quote>http://www.example.org.foobar.exit/</quote>
7302 to access the host <quote>www.example.org</quote> through the
7303 <command>Tor</command> exit node <quote>foobar</quote>.
7306 As the HTTP client isn't aware of this notation, it treats the
7307 whole string <quote>www.example.org.foobar.exit</quote> as host and uses it
7308 for the <quote>Host</quote> and <quote>Referer</quote> headers. From the
7309 server's point of view the resulting headers are invalid and can cause problems.
7312 An invalid <quote>Referer</quote> header can trigger <quote>hot-linking</quote>
7313 protections, an invalid <quote>Host</quote> header will make it impossible for
7314 the server to find the right vhost (several domains hosted on the same IP address).
7317 This client-header filter removes the <quote>foo.exit</quote> part in those headers
7318 to prevent the mentioned problems. Note that it only modifies
7319 the HTTP headers, it doesn't make it impossible for the server
7320 to detect your <command>Tor</command> exit node based on the IP address
7321 the request is coming from.
7328 <term><emphasis> </emphasis></term>
7341 <!-- ~~~~~~~~ New section Header ~~~~~~~~~ -->
7342 <sect2 id="external-filter-syntax"><title>External filter syntax</title>
7344 External filters are scripts or programs that can modify the content in
7345 case common <literal><link linkend="filter">filters</link></literal>
7346 aren't powerful enough.
7349 External filters can be written in any language the platform &my-app; runs
7353 They are controlled with the
7354 <literal><link linkend="external-filter">external-filter</link></literal> action
7355 and have to be defined in the <literal><link linkend="filterfile">filterfile</link></literal>
7359 The header looks like any other filter, but instead of pcrs jobs, external
7360 filters contain a single job which can be a program or a shell script (which
7361 may call other scripts or programs).
7364 External filters read the content from STDIN and write the rewritten
7366 The environment variables PRIVOXY_URL, PRIVOXY_PATH, PRIVOXY_HOST,
7367 PRIVOXY_ORIGIN, PRIVOXY_LISTEN_ADDRESS can be used to get some details
7368 about the client request.
7371 &my-app; will temporary store the content to filter in the
7372 <literal><link linkend="temporary-directory">temporary-directory</link></literal>.
7376 EXTERNAL-FILTER: cat Pointless example filter that doesn't actually modify the content
7379 # Incorrect reimplementation of the filter above in POSIX shell.
7381 # Note that it's a single job that spans multiple lines, the line
7382 # breaks are not passed to the shell, thus the semicolons are required.
7384 # If the script isn't trivial, it is recommended to put it into an external file.
7386 # In general, writing external filters entirely in POSIX shell is not
7387 # considered a good idea.
7388 EXTERNAL-FILTER: cat2 Pointless example filter that despite its name may actually modify the content
7394 EXTERNAL-FILTER: rotate-image Rotate an image by 180 degree. Test filter with limited value.
7395 /usr/local/bin/convert - -rotate 180 -
7397 EXTERNAL-FILTER: citation-needed Adds a "[citation needed]" tag to an image. The coordinates may need adjustment.
7398 /usr/local/bin/convert - -pointsize 16 -fill white -annotate +17+418 "[citation needed]" -
7403 Currently external filters are executed with &my-app;'s privileges!
7404 Only use external filters you understand and trust.
7408 External filters are experimental and the syntax may change in the future.
7414 <!-- ~ End section ~ -->
7418 <!-- ~~~~~ New section ~~~~~ -->
7420 <sect1 id="templates">
7421 <title>Privoxy's Template Files</title>
7423 All <application>Privoxy</application> built-in pages, i.e. error pages such as the
7424 <ulink url="http://show-the-404-error.page"><quote>404 - No Such Domain</quote>
7425 error page</ulink>, the <ulink
7426 url="http://ads.bannerserver.example.com/nasty-ads/sponsor.html"><quote>BLOCKED</quote>
7428 and all pages of its <ulink url="http://config.privoxy.org/">web-based
7429 user interface</ulink>, are generated from <emphasis>templates</emphasis>.
7430 (<application>Privoxy</application> must be running for the above links to work as
7435 These templates are stored in a subdirectory of the <link linkend="confdir">configuration
7436 directory</link> called <filename>templates</filename>. On Unixish platforms,
7438 <ulink url="file:///etc/privoxy/templates/"><filename>/etc/privoxy/templates/</filename></ulink>.
7442 The templates are basically normal HTML files, but with place-holders (called symbols
7443 or exports), which <application>Privoxy</application> fills at run time. It
7444 is possible to edit the templates with a normal text editor, should you want
7445 to customize them. (<emphasis>Not recommended for the casual
7446 user</emphasis>). Should you create your own custom templates, you should use
7447 the <filename>config</filename> setting <link linkend="templdir">templdir</link>
7448 to specify an alternate location, so your templates do not get overwritten
7452 Note that just like in configuration files, lines starting
7453 with <literal>#</literal> are ignored when the templates are filled in.
7457 The place-holders are of the form <literal>@name@</literal>, and you will
7458 find a list of available symbols, which vary from template to template,
7459 in the comments at the start of each file. Note that these comments are not
7460 always accurate, and that it's probably best to look at the existing HTML
7461 code to find out which symbols are supported and what they are filled in with.
7465 A special application of this substitution mechanism is to make whole
7466 blocks of HTML code disappear when a specific symbol is set. We use this
7467 for many purposes, one of them being to include the beta warning in all
7468 our user interface (CGI) pages when <application>Privoxy</application>
7469 is in an alpha or beta development stage:
7473 <!-- @if-unstable-start -->
7475 ... beta warning HTML code goes here ...
7477 <!-- if-unstable-end@ --></screen>
7480 If the "unstable" symbol is set, everything in between and including
7481 <literal>@if-unstable-start</literal> and <literal>if-unstable-end@</literal>
7482 will disappear, leaving nothing but an empty comment:
7485 <screen><!-- --></screen>
7488 There's also an if-then-else construct and an <literal>#include</literal>
7489 mechanism, but you'll sure find out if you are inclined to edit the
7494 All templates refer to a style located at
7495 <ulink url="http://config.privoxy.org/send-stylesheet"><literal>http://config.privoxy.org/send-stylesheet</literal></ulink>.
7496 This is, of course, locally served by <application>Privoxy</application>
7497 and the source for it can be found and edited in the
7498 <filename>cgi-style.css</filename> template.
7503 <!-- ~ End section ~ -->
7507 <!-- ~~~~~ New section ~~~~~ -->
7509 <sect1 id="contact"><title>Contacting the Developers, Bug Reporting and Feature
7512 <!-- Include contacting.sgml boilerplate: -->
7514 <!-- end boilerplate -->
7518 <!-- ~ End section ~ -->
7521 <!-- ~~~~~ New section ~~~~~ -->
7522 <sect1 id="copyright"><title>Privoxy Copyright, License and History</title>
7524 <!-- Include copyright.sgml: -->
7526 <!-- end copyright -->
7529 <application>Privoxy</application> is free software; you can
7530 redistribute it and/or modify it under the terms of the
7531 <citetitle>GNU General Public License</citetitle>, version 2,
7532 as published by the Free Software Foundation and included in
7536 <!-- ~~~~~ New section ~~~~~ -->
7537 <sect2 id="license"><title>License</title>
7539 <screen><![ RCDATA [ &GPLv2; ]]></screen>
7542 <!-- ~ End section ~ -->
7545 <!-- ~~~~~ New section ~~~~~ -->
7547 <sect2 id="history"><title>History</title>
7548 <!-- Include history.sgml: -->
7550 <!-- end history -->
7553 <sect2 id="authors"><title>Authors</title>
7554 <!-- Include p-authors.sgml: -->
7556 <!-- end authors -->
7561 <!-- ~ End section ~ -->
7564 <!-- ~~~~~ New section ~~~~~ -->
7565 <sect1 id="seealso"><title>See Also</title>
7566 <!-- Include seealso.sgml: -->
7568 <!-- end seealso -->
7573 <!-- ~~~~~ New section ~~~~~ -->
7574 <sect1 id="appendix"><title>Appendix</title>
7577 <!-- ~~~~~ New section ~~~~~ -->
7579 <title>Regular Expressions</title>
7581 <application>Privoxy</application> uses Perl-style <quote>regular
7582 expressions</quote> in its <link linkend="actions-file">actions
7583 files</link> and <link linkend="filter-file">filter file</link>,
7584 through the <ulink url="http://www.pcre.org/">PCRE</ulink> and
7587 <ulink url="http://www.oesterhelt.org/pcrs/">PCRS</ulink> libraries.
7589 <application>PCRS</application> libraries.
7593 If you are reading this, you probably don't understand what <quote>regular
7594 expressions</quote> are, or what they can do. So this will be a very brief
7595 introduction only. A full explanation would require a <ulink
7596 url="http://www.oreilly.com/catalog/regex/">book</ulink> ;-)
7600 Regular expressions provide a language to describe patterns that can be
7601 run against strings of characters (letter, numbers, etc), to see if they
7602 match the string or not. The patterns are themselves (sometimes complex)
7603 strings of literal characters, combined with wild-cards, and other special
7604 characters, called meta-characters. The <quote>meta-characters</quote> have
7605 special meanings and are used to build complex patterns to be matched against.
7606 Perl Compatible Regular Expressions are an especially convenient
7607 <quote>dialect</quote> of the regular expression language.
7611 To make a simple analogy, we do something similar when we use wild-card
7612 characters when listing files with the <command>dir</command> command in DOS.
7613 <literal>*.*</literal> matches all filenames. The <quote>special</quote>
7614 character here is the asterisk which matches any and all characters. We can be
7615 more specific and use <literal>?</literal> to match just individual
7616 characters. So <quote>dir file?.text</quote> would match
7617 <quote>file1.txt</quote>, <quote>file2.txt</quote>, etc. We are pattern
7618 matching, using a similar technique to <quote>regular expressions</quote>!
7622 Regular expressions do essentially the same thing, but are much, much more
7623 powerful. There are many more <quote>special characters</quote> and ways of
7624 building complex patterns however. Let's look at a few of the common ones,
7625 and then some examples:
7630 <emphasis>.</emphasis> - Matches any single character, e.g. <quote>a</quote>,
7631 <quote>A</quote>, <quote>4</quote>, <quote>:</quote>, or <quote>@</quote>.
7637 <emphasis>?</emphasis> - The preceding character or expression is matched ZERO or ONE
7644 <emphasis>+</emphasis> - The preceding character or expression is matched ONE or MORE
7651 <emphasis>*</emphasis> - The preceding character or expression is matched ZERO or MORE
7658 <emphasis>\</emphasis> - The <quote>escape</quote> character denotes that
7659 the following character should be taken literally. This is used where one of the
7660 special characters (e.g. <quote>.</quote>) needs to be taken literally and
7661 not as a special meta-character. Example: <quote>example\.com</quote>, makes
7662 sure the period is recognized only as a period (and not expanded to its
7663 meta-character meaning of any single character).
7669 <emphasis>[ ]</emphasis> - Characters enclosed in brackets will be matched if
7670 any of the enclosed characters are encountered. For instance, <quote>[0-9]</quote>
7671 matches any numeric digit (zero through nine). As an example, we can combine
7672 this with <quote>+</quote> to match any digit one of more times: <quote>[0-9]+</quote>.
7678 <emphasis>( )</emphasis> - parentheses are used to group a sub-expression,
7679 or multiple sub-expressions.
7685 <emphasis>|</emphasis> - The <quote>bar</quote> character works like an
7686 <quote>or</quote> conditional statement. A match is successful if the
7687 sub-expression on either side of <quote>|</quote> matches. As an example:
7688 <quote>/(this|that) example/</quote> uses grouping and the bar character
7689 and would match either <quote>this example</quote> or <quote>that
7690 example</quote>, and nothing else.
7695 These are just some of the ones you are likely to use when matching URLs with
7696 <application>Privoxy</application>, and is a long way from a definitive
7697 list. This is enough to get us started with a few simple examples which may
7698 be more illuminating:
7702 <emphasis><literal>/.*/banners/.*</literal></emphasis> - A simple example
7703 that uses the common combination of <quote>.</quote> and <quote>*</quote> to
7704 denote any character, zero or more times. In other words, any string at all.
7705 So we start with a literal forward slash, then our regular expression pattern
7706 (<quote>.*</quote>) another literal forward slash, the string
7707 <quote>banners</quote>, another forward slash, and lastly another
7708 <quote>.*</quote>. We are building
7709 a directory path here. This will match any file with the path that has a
7710 directory named <quote>banners</quote> in it. The <quote>.*</quote> matches
7711 any characters, and this could conceivably be more forward slashes, so it
7712 might expand into a much longer looking path. For example, this could match:
7713 <quote>/eye/hate/spammers/banners/annoy_me_please.gif</quote>, or just
7714 <quote>/banners/annoying.html</quote>, or almost an infinite number of other
7715 possible combinations, just so it has <quote>banners</quote> in the path
7720 And now something a little more complex:
7724 <emphasis><literal>/.*/adv((er)?ts?|ertis(ing|ements?))?/</literal></emphasis> -
7725 We have several literal forward slashes again (<quote>/</quote>), so we are
7726 building another expression that is a file path statement. We have another
7727 <quote>.*</quote>, so we are matching against any conceivable sub-path, just so
7728 it matches our expression. The only true literal that <emphasis>must
7729 match</emphasis> our pattern is <application>adv</application>, together with
7730 the forward slashes. What comes after the <quote>adv</quote> string is the
7735 Remember the <quote>?</quote> means the preceding expression (either a
7736 literal character or anything grouped with <quote>(...)</quote> in this case)
7737 can exist or not, since this means either zero or one match. So
7738 <quote>((er)?ts?|ertis(ing|ements?))</quote> is optional, as are the
7739 individual sub-expressions: <quote>(er)</quote>,
7740 <quote>(ing|ements?)</quote>, and the <quote>s</quote>. The <quote>|</quote>
7741 means <quote>or</quote>. We have two of those. For instance,
7742 <quote>(ing|ements?)</quote>, can expand to match either <quote>ing</quote>
7743 <emphasis>OR</emphasis> <quote>ements?</quote>. What is being done here, is an
7744 attempt at matching as many variations of <quote>advertisement</quote>, and
7745 similar, as possible. So this would expand to match just <quote>adv</quote>,
7746 or <quote>advert</quote>, or <quote>adverts</quote>, or
7747 <quote>advertising</quote>, or <quote>advertisement</quote>, or
7748 <quote>advertisements</quote>. You get the idea. But it would not match
7749 <quote>advertizements</quote> (with a <quote>z</quote>). We could fix that by
7750 changing our regular expression to:
7751 <quote>/.*/adv((er)?ts?|erti(s|z)(ing|ements?))?/</quote>, which would then match
7756 <emphasis><literal>/.*/advert[0-9]+\.(gif|jpe?g)</literal></emphasis> - Again
7757 another path statement with forward slashes. Anything in the square brackets
7758 <quote>[ ]</quote> can be matched. This is using <quote>0-9</quote> as a
7759 shorthand expression to mean any digit one through nine. It is the same as
7760 saying <quote>0123456789</quote>. So any digit matches. The <quote>+</quote>
7761 means one or more of the preceding expression must be included. The preceding
7762 expression here is what is in the square brackets -- in this case, any digit
7763 one through nine. Then, at the end, we have a grouping: <quote>(gif|jpe?g)</quote>.
7764 This includes a <quote>|</quote>, so this needs to match the expression on
7765 either side of that bar character also. A simple <quote>gif</quote> on one side, and the other
7766 side will in turn match either <quote>jpeg</quote> or <quote>jpg</quote>,
7767 since the <quote>?</quote> means the letter <quote>e</quote> is optional and
7768 can be matched once or not at all. So we are building an expression here to
7769 match image GIF or JPEG type image file. It must include the literal
7770 string <quote>advert</quote>, then one or more digits, and a <quote>.</quote>
7771 (which is now a literal, and not a special character, since it is escaped
7772 with <quote>\</quote>), and lastly either <quote>gif</quote>, or
7773 <quote>jpeg</quote>, or <quote>jpg</quote>. Some possible matches would
7774 include: <quote>//advert1.jpg</quote>,
7775 <quote>/nasty/ads/advert1234.gif</quote>,
7776 <quote>/banners/from/hell/advert99.jpg</quote>. It would not match
7777 <quote>advert1.gif</quote> (no leading slash), or
7778 <quote>/adverts232.jpg</quote> (the expression does not include an
7779 <quote>s</quote>), or <quote>/advert1.jsp</quote> (<quote>jsp</quote> is not
7780 in the expression anywhere).
7784 We are barely scratching the surface of regular expressions here so that you
7785 can understand the default <application>Privoxy</application>
7786 configuration files, and maybe use this knowledge to customize your own
7787 installation. There is much, much more that can be done with regular
7788 expressions. Now that you know enough to get started, you can learn more on
7793 More reading on Perl Compatible Regular expressions:
7794 <ulink url="http://perldoc.perl.org/perlre.html">http://perldoc.perl.org/perlre.html</ulink>
7798 For information on regular expression based substitutions and their applications
7799 in filters, please see the <link linkend="filter-file">filter file tutorial</link>
7804 <!-- ~ End section ~ -->
7807 <!-- ~~~~~ New section ~~~~~ -->
7808 <sect2 id="internal-pages">
7809 <title>Privoxy's Internal Pages</title>
7812 Since <application>Privoxy</application> proxies each requested
7813 web page, it is easy for <application>Privoxy</application> to
7814 trap certain special URLs. In this way, we can talk directly to
7815 <application>Privoxy</application>, and see how it is
7816 configured, see how our rules are being applied, change these
7817 rules and other configuration options, and even turn
7818 <application>Privoxy's</application> filtering off, all with
7823 The URLs listed below are the special ones that allow direct access
7824 to <application>Privoxy</application>. Of course,
7825 <application>Privoxy</application> must be running to access these. If
7826 not, you will get a friendly error message. Internet access is not
7838 <ulink url="http://config.privoxy.org/">http://config.privoxy.org/</ulink>
7842 There is a shortcut: <ulink url="http://p.p/">http://p.p/</ulink> (But it
7843 doesn't provide a fall-back to a real page, in case the request is not
7844 sent through <application>Privoxy</application>)
7850 Show information about the current configuration, including viewing and
7851 editing of actions files:
7855 <ulink url="http://config.privoxy.org/show-status">http://config.privoxy.org/show-status</ulink>
7862 Show the source code version numbers:
7866 <ulink url="http://config.privoxy.org/show-version">http://config.privoxy.org/show-version</ulink>
7873 Show the browser's request headers:
7877 <ulink url="http://config.privoxy.org/show-request">http://config.privoxy.org/show-request</ulink>
7884 Show which actions apply to a URL and why:
7888 <ulink url="http://config.privoxy.org/show-url-info">http://config.privoxy.org/show-url-info</ulink>
7895 Toggle Privoxy on or off. This feature can be turned off/on in the main
7896 <filename>config</filename> file. When toggled <quote>off</quote>, <quote>Privoxy</quote>
7897 continues to run, but only as a pass-through proxy, with no actions taking
7902 <ulink url="http://config.privoxy.org/toggle">http://config.privoxy.org/toggle</ulink>
7906 Short cuts. Turn off, then on:
7910 <ulink url="http://config.privoxy.org/toggle?set=disable">http://config.privoxy.org/toggle?set=disable</ulink>
7915 <ulink url="http://config.privoxy.org/toggle?set=enable">http://config.privoxy.org/toggle?set=enable</ulink>
7925 <!-- ~~~~~ New section ~~~~~ -->
7927 <title>Chain of Events</title>
7929 Let's take a quick look at how some of <application>Privoxy's</application>
7930 core features are triggered, and the ensuing sequence of events when a web
7931 page is requested by your browser:
7937 First, your web browser requests a web page. The browser knows to send
7938 the request to <application>Privoxy</application>, which will in turn,
7939 relay the request to the remote web server after passing the following
7945 <application>Privoxy</application> traps any request for its own internal CGI
7946 pages (e.g <ulink url="http://p.p/">http://p.p/</ulink>) and sends the CGI page back to the browser.
7951 Next, <application>Privoxy</application> checks to see if the URL
7953 linkend="BLOCK"><quote>+block</quote></link> patterns. If
7954 so, the URL is then blocked, and the remote web server will not be contacted.
7955 <link linkend="HANDLE-AS-IMAGE"><quote>+handle-as-image</quote></link>
7957 <link linkend="HANDLE-AS-EMPTY-DOCUMENT"><quote>+handle-as-empty-document</quote></link>
7958 are then checked, and if there is no match, an
7959 HTML <quote>BLOCKED</quote> page is sent back to the browser. Otherwise, if
7960 it does match, an image is returned for the former, and an empty text
7961 document for the latter. The type of image would depend on the setting of
7962 <link linkend="SET-IMAGE-BLOCKER"><quote>+set-image-blocker</quote></link>
7963 (blank, checkerboard pattern, or an HTTP redirect to an image elsewhere).
7968 Untrusted URLs are blocked. If URLs are being added to the
7969 <filename>trust</filename> file, then that is done.
7974 If the URL pattern matches the <link
7975 linkend="FAST-REDIRECTS"><quote>+fast-redirects</quote></link> action,
7976 it is then processed. Unwanted parts of the requested URL are stripped.
7981 Now the rest of the client browser's request headers are processed. If any
7982 of these match any of the relevant actions (e.g. <link
7983 linkend="HIDE-USER-AGENT"><quote>+hide-user-agent</quote></link>,
7984 etc.), headers are suppressed or forged as determined by these actions and
7990 Now the web server starts sending its response back (i.e. typically a web
7996 First, the server headers are read and processed to determine, among other
7997 things, the MIME type (document type) and encoding. The headers are then
7998 filtered as determined by the
7999 <link linkend="CRUNCH-INCOMING-COOKIES"><quote>+crunch-incoming-cookies</quote></link>,
8000 <link linkend="SESSION-COOKIES-ONLY"><quote>+session-cookies-only</quote></link>,
8001 and <link linkend="DOWNGRADE-HTTP-VERSION"><quote>+downgrade-http-version</quote></link>
8007 If any <link linkend="FILTER"><quote>+filter</quote></link> action
8009 linkend="DEANIMATE-GIFS"><quote>+deanimate-gifs</quote></link>
8010 action applies (and the document type fits the action), the rest of the page is
8011 read into memory (up to a configurable limit). Then the filter rules (from
8012 <filename>default.filter</filename> and any other filter files) are
8013 processed against the buffered content. Filters are applied in the order
8014 they are specified in one of the filter files. Animated GIFs, if present,
8015 are reduced to either the first or last frame, depending on the action
8016 setting.The entire page, which is now filtered, is then sent by
8017 <application>Privoxy</application> back to your browser.
8020 If neither a <link linkend="FILTER"><quote>+filter</quote></link> action
8022 linkend="DEANIMATE-GIFS"><quote>+deanimate-gifs</quote></link>
8023 matches, then <application>Privoxy</application> passes the raw data through
8024 to the client browser as it becomes available.
8029 As the browser receives the now (possibly filtered) page content, it
8030 reads and then requests any URLs that may be embedded within the page
8031 source, e.g. ad images, stylesheets, JavaScript, other HTML documents (e.g.
8032 frames), sounds, etc. For each of these objects, the browser issues a
8033 separate request (this is easily viewable in <application>Privoxy's</application>
8034 logs). And each such request is in turn processed just as above. Note that a
8035 complex web page will have many, many such embedded URLs. If these
8036 secondary requests are to a different server, then quite possibly a very
8037 differing set of actions is triggered.
8044 NOTE: This is somewhat of a simplistic overview of what happens with each URL
8045 request. For the sake of brevity and simplicity, we have focused on
8046 <application>Privoxy's</application> core features only.
8052 <!-- ~~~~~ New section ~~~~~ -->
8053 <sect2 id="actionsanat">
8054 <title>Troubleshooting: Anatomy of an Action</title>
8057 The way <application>Privoxy</application> applies
8058 <link linkend="ACTIONS">actions</link> and <link linkend="FILTER">filters</link>
8059 to any given URL can be complex, and not always so
8060 easy to understand what is happening. And sometimes we need to be able to
8061 <emphasis>see</emphasis> just what <application>Privoxy</application> is
8062 doing. Especially, if something <application>Privoxy</application> is doing
8063 is causing us a problem inadvertently. It can be a little daunting to look at
8064 the actions and filters files themselves, since they tend to be filled with
8065 <link linkend="regex">regular expressions</link> whose consequences are not
8070 One quick test to see if <application>Privoxy</application> is causing a problem
8071 or not, is to disable it temporarily. This should be the first troubleshooting
8072 step (be sure to flush caches afterward!). Looking at the
8073 logs is a good idea too. (Note that both the toggle feature and logging are
8074 enabled via <filename>config</filename> file settings, and may need to be
8075 turned <quote>on</quote>.)
8078 Another easy troubleshooting step to try is if you have done any
8079 customization of your installation, revert back to the installed
8080 defaults and see if that helps. There are times the developers get complaints
8081 about one thing or another, and the problem is more related to a customized
8082 configuration issue.
8086 <application>Privoxy</application> also provides the
8087 <ulink url="http://config.privoxy.org/show-url-info">http://config.privoxy.org/show-url-info</ulink>
8088 page that can show us very specifically how <application>actions</application>
8089 are being applied to any given URL. This is a big help for troubleshooting.
8093 First, enter one URL (or partial URL) at the prompt, and then
8094 <application>Privoxy</application> will tell us
8095 how the current configuration will handle it. This will not
8096 help with filtering effects (i.e. the <link
8097 linkend="FILTER"><quote>+filter</quote></link> action) from
8098 one of the filter files since this is handled very
8099 differently and not so easy to trap! It also will not tell you about any other
8100 URLs that may be embedded within the URL you are testing. For instance, images
8101 such as ads are expressed as URLs within the raw page source of HTML pages. So
8102 you will only get info for the actual URL that is pasted into the prompt area
8103 -- not any sub-URLs. If you want to know about embedded URLs like ads, you
8104 will have to dig those out of the HTML source. Use your browser's <quote>View
8105 Page Source</quote> option for this. Or right click on the ad, and grab the
8110 Let's try an example, <ulink url="http://google.com">google.com</ulink>,
8111 and look at it one section at a time in a sample configuration (your real
8112 configuration may vary):
8116 Matches for http://www.google.com:
8118 In file: default.action <guibutton>[ View ]</guibutton> <guibutton>[ Edit ]</guibutton>
8120 {+change-x-forwarded-for{block}
8121 +deanimate-gifs {last}
8122 +fast-redirects {check-decoded-url}
8123 +filter {refresh-tags}
8124 +filter {img-reorder}
8125 +filter {banners-by-size}
8127 +filter {jumping-windows}
8128 +filter {ie-exploits}
8129 +hide-from-header {block}
8130 +hide-referrer {forge}
8131 +session-cookies-only
8132 +set-image-blocker {pattern}
8135 { -session-cookies-only }
8141 In file: user.action <guibutton>[ View ]</guibutton> <guibutton>[ Edit ]</guibutton>
8142 (no matches in this file)
8146 This is telling us how we have defined our
8147 <link linkend="ACTIONS"><quote>actions</quote></link>, and
8148 which ones match for our test case, <quote>google.com</quote>.
8149 Displayed is all the actions that are available to us. Remember,
8150 the <literal>+</literal> sign denotes <quote>on</quote>. <literal>-</literal>
8151 denotes <quote>off</quote>. So some are <quote>on</quote> here, but many
8152 are <quote>off</quote>. Each example we try may provide a slightly different
8153 end result, depending on our configuration directives.
8157 is for our <filename>default.action</filename> file. The large, multi-line
8158 listing, is how the actions are set to match for all URLs, i.e. our default
8159 settings. If you look at your <quote>actions</quote> file, this would be the
8160 section just below the <quote>aliases</quote> section near the top. This
8161 will apply to all URLs as signified by the single forward slash at the end
8162 of the listing -- <quote> / </quote>.
8166 But we have defined additional actions that would be exceptions to these general
8167 rules, and then we list specific URLs (or patterns) that these exceptions
8168 would apply to. Last match wins. Just below this then are two explicit
8169 matches for <quote>.google.com</quote>. The first is negating our previous
8170 cookie setting, which was for <link
8171 linkend="SESSION-COOKIES-ONLY"><quote>+session-cookies-only</quote></link>
8172 (i.e. not persistent). So we will allow persistent cookies for google, at
8173 least that is how it is in this example. The second turns
8174 <emphasis>off</emphasis> any <link
8175 linkend="FAST-REDIRECTS"><quote>+fast-redirects</quote></link>
8176 action, allowing this to take place unmolested. Note that there is a leading
8177 dot here -- <quote>.google.com</quote>. This will match any hosts and
8178 sub-domains, in the google.com domain also, such as
8179 <quote>www.google.com</quote> or <quote>mail.google.com</quote>. But it would not
8180 match <quote>www.google.de</quote>! So, apparently, we have these two actions
8181 defined as exceptions to the general rules at the top somewhere in the lower
8182 part of our <filename>default.action</filename> file, and
8183 <quote>google.com</quote> is referenced somewhere in these latter sections.
8187 Then, for our <filename>user.action</filename> file, we again have no hits.
8188 So there is nothing google-specific that we might have added to our own, local
8189 configuration. If there was, those actions would over-rule any actions from
8190 previously processed files, such as <filename>default.action</filename>.
8191 <filename>user.action</filename> typically has the last word. This is the
8192 best place to put hard and fast exceptions,
8196 And finally we pull it all together in the bottom section and summarize how
8197 <application>Privoxy</application> is applying all its <quote>actions</quote>
8198 to <quote>google.com</quote>:
8206 +change-x-forwarded-for{block}
8207 -client-header-filter{hide-tor-exit-notation}
8208 -content-type-overwrite
8209 -crunch-client-header
8210 -crunch-if-none-match
8211 -crunch-incoming-cookies
8212 -crunch-outgoing-cookies
8213 -crunch-server-header
8214 +deanimate-gifs {last}
8215 -downgrade-http-version
8218 -filter {content-cookies}
8219 -filter {all-popups}
8220 -filter {banners-by-link}
8221 -filter {tiny-textforms}
8222 -filter {frameset-borders}
8223 -filter {demoronizer}
8224 -filter {shockwave-flash}
8225 -filter {quicktime-kioskmode}
8227 -filter {crude-parental}
8228 -filter {site-specifics}
8229 -filter {js-annoyances}
8230 -filter {html-annoyances}
8231 +filter {refresh-tags}
8232 -filter {unsolicited-popups}
8233 +filter {img-reorder}
8234 +filter {banners-by-size}
8236 +filter {jumping-windows}
8237 +filter {ie-exploits}
8244 -handle-as-empty-document
8246 -hide-accept-language
8247 -hide-content-disposition
8248 +hide-from-header {block}
8249 -hide-if-modified-since
8250 +hide-referrer {forge}
8253 -overwrite-last-modified
8254 -prevent-compression
8256 -server-header-filter{xml-to-html}
8257 -server-header-filter{html-to-xml}
8258 -session-cookies-only
8259 +set-image-blocker {pattern} </screen>
8262 Notice the only difference here to the previous listing, is to
8263 <quote>fast-redirects</quote> and <quote>session-cookies-only</quote>,
8264 which are activated specifically for this site in our configuration,
8265 and thus show in the <quote>Final Results</quote>.
8269 Now another example, <quote>ad.doubleclick.net</quote>:
8273 { +block{Domains starts with "ad"} }
8276 { +block{Domain contains "ad"} }
8279 { +block{Doubleclick banner server} +handle-as-image }
8280 .[a-vx-z]*.doubleclick.net
8284 We'll just show the interesting part here - the explicit matches. It is
8285 matched three different times. Two <quote>+block{}</quote> sections,
8286 and a <quote>+block{} +handle-as-image</quote>,
8287 which is the expanded form of one of our aliases that had been defined as:
8288 <quote>+block-as-image</quote>. (<link
8289 linkend="ALIASES"><quote>Aliases</quote></link> are defined in
8290 the first section of the actions file and typically used to combine more
8295 Any one of these would have done the trick and blocked this as an unwanted
8296 image. This is unnecessarily redundant since the last case effectively
8297 would also cover the first. No point in taking chances with these guys
8298 though ;-) Note that if you want an ad or obnoxious
8299 URL to be invisible, it should be defined as <quote>ad.doubleclick.net</quote>
8300 is done here -- as both a <link
8301 linkend="BLOCK"><quote>+block{}</quote></link>
8302 <emphasis>and</emphasis> an
8303 <link linkend="HANDLE-AS-IMAGE"><quote>+handle-as-image</quote></link>.
8304 The custom alias <quote><literal>+block-as-image</literal></quote> just
8305 simplifies the process and make it more readable.
8309 One last example. Let's try <quote>http://www.example.net/adsl/HOWTO/</quote>.
8310 This one is giving us problems. We are getting a blank page. Hmmm ...
8314 Matches for http://www.example.net/adsl/HOWTO/:
8316 In file: default.action <guibutton>[ View ]</guibutton> <guibutton>[ Edit ]</guibutton>
8320 +change-x-forwarded-for{block}
8321 -client-header-filter{hide-tor-exit-notation}
8322 -content-type-overwrite
8323 -crunch-client-header
8324 -crunch-if-none-match
8325 -crunch-incoming-cookies
8326 -crunch-outgoing-cookies
8327 -crunch-server-header
8329 -downgrade-http-version
8330 +fast-redirects {check-decoded-url}
8332 -filter {content-cookies}
8333 -filter {all-popups}
8334 -filter {banners-by-link}
8335 -filter {tiny-textforms}
8336 -filter {frameset-borders}
8337 -filter {demoronizer}
8338 -filter {shockwave-flash}
8339 -filter {quicktime-kioskmode}
8341 -filter {crude-parental}
8342 -filter {site-specifics}
8343 -filter {js-annoyances}
8344 -filter {html-annoyances}
8345 +filter {refresh-tags}
8346 -filter {unsolicited-popups}
8347 +filter {img-reorder}
8348 +filter {banners-by-size}
8350 +filter {jumping-windows}
8351 +filter {ie-exploits}
8358 -handle-as-empty-document
8360 -hide-accept-language
8361 -hide-content-disposition
8362 +hide-from-header{block}
8363 +hide-referer{forge}
8365 -overwrite-last-modified
8366 +prevent-compression
8368 -server-header-filter{xml-to-html}
8369 -server-header-filter{html-to-xml}
8370 +session-cookies-only
8371 +set-image-blocker{blank} }
8374 { +block{Path contains "ads".} +handle-as-image }
8379 Ooops, the <quote>/adsl/</quote> is matching <quote>/ads</quote> in our
8380 configuration! But we did not want this at all! Now we see why we get the
8381 blank page. It is actually triggering two different actions here, and
8382 the effects are aggregated so that the URL is blocked, and &my-app; is told
8383 to treat the block as if it were an image. But this is, of course, all wrong.
8384 We could now add a new action below this (or better in our own
8385 <filename>user.action</filename> file) that explicitly
8386 <emphasis>un</emphasis> blocks (
8387 <link linkend="BLOCK"><quote>{-block}</quote></link>) paths with
8388 <quote>adsl</quote> in them (remember, last match in the configuration
8389 wins). There are various ways to handle such exceptions. Example:
8398 Now the page displays ;-)
8399 Remember to flush your browser's caches when making these kinds of changes to
8400 your configuration to insure that you get a freshly delivered page! Or, try
8401 using <literal>Shift+Reload</literal>.
8405 But now what about a situation where we get no explicit matches like
8410 { +block{Path starts with "ads".} +handle-as-image }
8415 That actually was very helpful and pointed us quickly to where the problem
8416 was. If you don't get this kind of match, then it means one of the default
8417 rules in the first section of <filename>default.action</filename> is causing
8418 the problem. This would require some guesswork, and maybe a little trial and
8419 error to isolate the offending rule. One likely cause would be one of the
8420 <link linkend="FILTER"><quote>+filter</quote></link> actions.
8421 These tend to be harder to troubleshoot.
8422 Try adding the URL for the site to one of aliases that turn off
8423 <link linkend="FILTER"><quote>+filter</quote></link>:
8429 .worldpay.com # for quietpc.com
8436 <quote><literal>{ shop }</literal></quote> is an <quote>alias</quote> that expands to
8437 <quote><literal>{ -filter -session-cookies-only }</literal></quote>.
8438 Or you could do your own exception to negate filtering:
8443 # Disable ALL filter actions for sites in this section
8450 This would turn off all filtering for these sites. This is best
8451 put in <filename>user.action</filename>, for local site
8452 exceptions. Note that when a simple domain pattern is used by itself (without
8453 the subsequent path portion), all sub-pages within that domain are included
8454 automatically in the scope of the action.
8458 Images that are inexplicably being blocked, may well be hitting the
8459 <link linkend="FILTER-BANNERS-BY-SIZE"><quote>+filter{banners-by-size}</quote></link>
8461 that images of certain sizes are ad banners (works well
8462 <emphasis>most of the time</emphasis> since these tend to be standardized).
8466 <quote><literal>{ fragile }</literal></quote> is an alias that disables most
8467 actions that are the most likely to cause trouble. This can be used as a
8468 last resort for problem sites.
8473 # Handle with care: easy to break
8475 mybank.example.com</screen>
8479 <emphasis>Remember to flush caches!</emphasis> Note that the
8480 <literal>mail.google</literal> reference lacks the TLD portion (e.g.
8481 <quote>.com</quote>). This will effectively match any TLD with
8482 <literal>google</literal> in it, such as <literal>mail.google.de.</literal>,
8486 If this still does not work, you will have to go through the remaining
8487 actions one by one to find which one(s) is causing the problem.
8496 This program is free software; you can redistribute it
8497 and/or modify it under the terms of the GNU General
8498 Public License as published by the Free Software
8499 Foundation; either version 2 of the License, or (at
8500 your option) any later version.
8502 This program is distributed in the hope that it will
8503 be useful, but WITHOUT ANY WARRANTY; without even the
8504 implied warranty of MERCHANTABILITY or FITNESS FOR A
8505 PARTICULAR PURPOSE. See the GNU General Public
8506 License for more details.
8508 The GNU General Public License should be included with
8509 this file. If not, you can view it at
8510 http://www.gnu.org/copyleft/gpl.html
8511 or write to the Free Software Foundation, Inc.,
8512 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
projects / privoxy.git / blob