1 <!DOCTYPE article PUBLIC "-//OASIS//DTD DocBook V3.1//EN" [
2 <!entity % dummy "IGNORE">
3 <!entity supported SYSTEM "supported.sgml">
4 <!entity newfeatures SYSTEM "newfeatures.sgml">
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6 <!entity seealso SYSTEM "seealso.sgml">
7 <!entity buildsource SYSTEM "buildsource.sgml">
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10 <!entity copyright SYSTEM "copyright.sgml">
11 <!entity license SYSTEM "license.sgml">
12 <!entity GPLv2 SYSTEM "../../LICENSE">
13 <!entity p-authors SYSTEM "p-authors.sgml">
14 <!entity config SYSTEM "p-config.sgml">
15 <!entity changelog SYSTEM "changelog.sgml">
16 <!entity p-version "3.0.24">
17 <!entity p-status "stable">
18 <!entity % p-authors-formal "INCLUDE"> <!-- include additional text, etc -->
19 <!entity % p-not-stable "IGNORE">
20 <!entity % p-stable "INCLUDE">
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23 <!entity % p-readme "IGNORE">
24 <!entity % user-man "IGNORE">
25 <!entity % config-file "IGNORE">
26 <!entity % p-supp-userman "IGNORE"> <!-- Omit some from supported.sgml -->
27 <!entity my-copy "©"> <!-- kludge for docbook2man -->
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30 <!entity my-app "<application>Privoxy</application>">
33 File : $Source: /cvsroot/ijbswa/current/doc/source/user-manual.sgml,v $
36 This file belongs into
37 ijbswa.sourceforge.net:/home/groups/i/ij/ijbswa/htdocs/
39 $Id: user-manual.sgml,v 2.200 2016/01/23 11:59:20 fabiankeil Exp $
41 Copyright (C) 2001-2014 Privoxy Developers http://www.privoxy.org/
44 ========================================================================
45 NOTE: Please read developer-manual/documentation.html before touching
46 anything in this, or other Privoxy documentation.
47 ========================================================================
54 <title>Privoxy &p-version; User Manual</title>
58 <!-- Completely the wrong markup, but very little is allowed -->
59 <!-- in this part of an article. FIXME -->
60 <link linkend="copyright">Copyright</link> &my-copy; 2001-2014 by
61 <ulink url="http://www.privoxy.org/">Privoxy Developers</ulink>
65 <pubdate>$Id: user-manual.sgml,v 2.200 2016/01/23 11:59:20 fabiankeil Exp $</pubdate>
69 Note: the following should generate a separate page, and a live link to it,
70 all nicely done. But it doesn't for some mysterious reason. Please leave
71 commented unless it can be fixed proper. For the time being, the
72 copyright/license declarations will be in their own sgml.
85 This is here to keep vim syntax file from breaking :/
86 If I knew enough to fix it, I would.
87 PLEASE DO NOT REMOVE! HB: hal@foobox.net
93 The <citetitle>Privoxy User Manual</citetitle> gives users information on how to
94 install, configure and use <ulink
95 url="http://www.privoxy.org/">Privoxy</ulink>.
98 <!-- Include privoxy.sgml boilerplate: -->
100 <!-- end privoxy.sgml -->
103 You can find the latest version of the <citetitle>Privoxy User Manual</citetitle> at <ulink
104 url="http://www.privoxy.org/user-manual/">http://www.privoxy.org/user-manual/</ulink>.
105 Please see the <link linkend="contact">Contact section</link> on how to
106 contact the developers.
110 <!-- Feel free to send a note to the developers at <email>ijbswa-developers@lists.sourceforge.net</email>. -->
116 <!-- ~~~~~ New section ~~~~~ -->
117 <sect1 label="1" id="introduction"><title>Introduction</title>
119 This documentation is included with the current &p-status; version of
120 <application>Privoxy</application>, &p-version;<![%p-not-stable;[,
121 and is mostly complete at this point. The most up to date reference for the
122 time being is still the comments in the source files and in the individual
123 configuration files. Development of a new version is currently nearing
124 completion, and includes significant changes and enhancements over
128 <!-- include only in non-stable versions -->
131 Since this is a &p-status; version, not all new features are well tested. This
132 documentation may be slightly out of sync as a result (especially with
133 CVS sources). And there <emphasis>may be</emphasis> bugs, though hopefully
138 <!-- ~~~~~ New section ~~~~~ -->
139 <sect2 id="features"><title>Features</title>
141 In addition to the core
142 features of ad blocking and
143 <ulink url="http://en.wikipedia.org/wiki/Browser_cookie">cookie</ulink> management,
144 <application>Privoxy</application> provides many supplemental
145 features<![%p-not-stable;[, some of them currently under development]]>,
146 that give the end-user more control, more privacy and more freedom:
148 <!-- Include newfeatures.sgml boilerplate here: -->
150 <!-- end boilerplate -->
155 <!-- ~ End section ~ -->
158 <!-- ~~~~~ New section ~~~~~ -->
159 <sect1 id="installation"><title>Installation</title>
162 <application>Privoxy</application> is available both in convenient pre-compiled
163 packages for a wide range of operating systems, and as raw source code.
164 For most users, we recommend using the packages, which can be downloaded from our
165 <ulink url="http://sourceforge.net/projects/ijbswa/">Privoxy Project
171 On some platforms, the installer may remove previously installed versions, if
172 found. (See below for your platform). In any case <emphasis>be sure to backup
173 your old configuration if it is valuable to you.</emphasis> See the <link
174 linkend="upgradersnote">note to upgraders</link> section below.
177 <!-- ~~~~~ New section ~~~~~ -->
178 <sect2 id="installation-packages"><title>Binary Packages</title>
180 How to install the binary packages depends on your operating system:
183 <!-- XXX: The installation sections should be sorted -->
185 <!-- ~~~~~ New section ~~~~~ -->
186 <sect3 id="installation-deb"><title>Debian and Ubuntu</title>
188 DEBs can be installed with <literal>apt-get install privoxy</literal>,
189 and will use <filename>/etc/privoxy</filename> for the location of
194 <!-- ~~~~~ New section ~~~~~ -->
195 <sect3 id="installation-pack-win"><title>Windows</title>
198 Just double-click the installer, which will guide you through
199 the installation process. You will find the configuration files
200 in the same directory as you installed <application>Privoxy</application> in.
203 Version 3.0.5 beta introduced full <application>Windows</application> service
204 functionality. On Windows only, the <application>Privoxy</application>
205 program has two new command line arguments to install and uninstall
206 <application>Privoxy</application> as a <emphasis>service</emphasis>.
210 <term>Arguments:</term>
213 <replaceable class="parameter">--install</replaceable>[:<replaceable class="parameter">service_name</replaceable>]
216 <replaceable class="parameter">--uninstall</replaceable>[:<replaceable class="parameter">service_name</replaceable>]
222 After invoking <application>Privoxy</application> with
223 <command>--install</command>, you will need to bring up the
224 <application>Windows</application> service console to assign the user you
225 want <application>Privoxy</application> to run under, and whether or not you
226 want it to run whenever the system starts. You can start the
227 <application>Windows</application> services console with the following
228 command: <command>services.msc</command>. If you do not take the manual step
229 of modifying <application>Privoxy's</application> service settings, it will
230 not start. Note too that you will need to give Privoxy a user account that
231 actually exists, or it will not be permitted to
232 write to its log and configuration files.
237 <!-- ~~~~~ New section ~~~~~ -->
238 <sect3 id="installation-os2"><title>OS/2</title>
241 First, make sure that no previous installations of
242 <application>Junkbuster</application> and / or
243 <application>Privoxy</application> are left on your
244 system. Check that no <application>Junkbuster</application>
245 or <application>Privoxy</application> objects are in
251 Then, just double-click the WarpIN self-installing archive, which will
252 guide you through the installation process. A shadow of the
253 <application>Privoxy</application> executable will be placed in your
254 startup folder so it will start automatically whenever OS/2 starts.
258 The directory you choose to install <application>Privoxy</application>
259 into will contain all of the configuration files.
263 <!-- ~~~~~ New section ~~~~~ -->
264 <sect3 id="installation-mac"><title>Mac OS X</title>
266 Installation instructions for the OS X platform depend upon whether
267 you downloaded a ready-built installation package (.pkg or .mpkg) or have
268 downloaded the source code.
271 <sect3 renderas="sect4" id="OS-X-install-from-package">
272 <title>Installation from ready-built package</title>
274 The downloaded file will either be a .pkg (for OS X 10.5 upwards) or a bzipped
275 .mpkg file (for OS X 10.4). The former can be double-clicked as is and the
276 installation will start; double-clicking the latter will unzip the .mpkg file
277 which can then be double-clicked to commence the installation.
280 The privoxy service will automatically start after a successful installation
281 (and thereafter every time your computer starts up) however you will need to
282 configure your web browser(s) to use it. To do so, configure them to use a
283 proxy for HTTP and HTTPS at the address 127.0.0.1:8118.
286 To prevent the privoxy service from automatically starting when your computer
287 starts up, remove or rename the file <literal>/Library/LaunchDaemons/org.ijbswa.privoxy.plist</literal>
288 (on OS X 10.5 and higher) or the folder named
289 <literal>/Library/StartupItems/Privoxy</literal> (on OS X 10.4 'Tiger').
292 To manually start or stop the privoxy service, use the scripts startPrivoxy.sh
293 and stopPrivoxy.sh supplied in /Applications/Privoxy. They must be run from an
294 administrator account, using sudo.
297 To uninstall, run /Applications/Privoxy/uninstall.command as sudo from an
298 administrator account.
301 <sect3 renderas="sect4" id="OS-X-install-from-source">
302 <title>Installation from source</title>
304 To build and install the Privoxy source code on OS X you will need to obtain
305 the macsetup module from the Privoxy Sourceforge CVS repository (refer to
306 Sourceforge help for details of how to set up a CVS client to have read-only
307 access to the repository). This module contains scripts that leverage the usual
308 open-source tools (available as part of Apple's free of charge Xcode
309 distribution or via the usual open-source software package managers for OS X
310 (MacPorts, Homebrew, Fink etc.) to build and then install the privoxy binary
311 and associated files. The macsetup module's README file contains complete
312 instructions for its use.
315 The privoxy service will automatically start after a successful installation
316 (and thereafter every time your computer starts up) however you will need to
317 configure your web browser(s) to use it. To do so, configure them to use a
318 proxy for HTTP and HTTPS at the address 127.0.0.1:8118.
321 To prevent the privoxy service from automatically starting when your computer
322 starts up, remove or rename the file <literal>/Library/LaunchDaemons/org.ijbswa.privoxy.plist</literal>
323 (on OS X 10.5 and higher) or the folder named
324 <literal>/Library/StartupItems/Privoxy</literal> (on OS X 10.4 'Tiger').
327 To manually start or stop the privoxy service, use the Privoxy Utility
328 for Mac OS X (also part of the macsetup module). This application can start
329 and stop the privoxy service and display its log and configuration files.
332 To uninstall, run the macsetup module's uninstall.sh as sudo from an
333 administrator account.
337 <!-- ~~~~~ New section ~~~~~ -->
338 <sect3 id="installation-freebsd"><title>FreeBSD</title>
341 Privoxy is part of FreeBSD's Ports Collection, you can build and install
342 it with <literal>cd /usr/ports/www/privoxy; make install clean</literal>.
348 <!-- ~~~~~ New section ~~~~~ -->
349 <sect2 id="installation-source"><title>Building from Source</title>
352 The most convenient way to obtain the <application>Privoxy</application> sources
353 is to download the source tarball from our
354 <ulink url="http://sourceforge.net/project/showfiles.php?group_id=11118&package_id=10571">project download
359 If you like to live on the bleeding edge and are not afraid of using
360 possibly unstable development versions, you can check out the up-to-the-minute
361 version directly from <ulink url="http://sourceforge.net/cvs/?group_id=11118">the
362 CVS repository</ulink>.
364 deprecated...out of business.
365 or simply download <ulink
366 url="http://cvs.sourceforge.net/cvstarballs/ijbswa-cvsroot.tar.bz2">the nightly CVS
371 <!-- include buildsource.sgml boilerplate: -->
373 <!-- end boilerplate -->
376 <!-- ~~~~~ New section ~~~~~ -->
377 <sect2 id="installation-keepupdated"><title>Keeping your Installation Up-to-Date</title>
380 If you wish to receive an email notification whenever we release updates of
381 <application>Privoxy</application> or the actions file, <ulink
382 url="http://lists.sourceforge.net/lists/listinfo/ijbswa-announce/">subscribe
383 to our announce mailing list</ulink>, ijbswa-announce@lists.sourceforge.net.
387 In order not to lose your personal changes and adjustments when updating
388 to the latest <literal>default.action</literal> file we <emphasis>strongly
389 recommend</emphasis> that you use <literal>user.action</literal> and
390 <literal>user.filter</literal> for your local
391 customizations of <application>Privoxy</application>. See the <link
392 linkend="actions-file">Chapter on actions files</link> for details.
400 <!-- ~ End section ~ -->
402 <!-- ~~~~~ New section ~~~~~ -->
403 <sect1 id="whatsnew">
404 <title>What's New in this Release</title>
408 <!-- ~~~~~ New section ~~~~~ -->
410 <sect2 id="upgradersnote">
411 <title>Note to Upgraders</title>
414 A quick list of things to be aware of before upgrading from earlier
415 versions of <application>Privoxy</application>:
423 The recommended way to upgrade &my-app; is to backup your old
424 configuration files, install the new ones, verify that &my-app;
425 is working correctly and finally merge back your changes using
426 <application>diff</application> and maybe <application>patch</application>.
429 There are a number of new features in each &my-app; release and
430 most of them have to be explicitly enabled in the configuration
431 files. Old configuration files obviously don't do that and due
432 to syntax changes using old configuration files with a new
433 &my-app; isn't always possible anyway.
438 Note that some installers remove earlier versions completely,
439 including configuration files, therefore you should really save
440 any important configuration files!
445 On the other hand, other installers don't overwrite existing configuration
446 files, thinking you will want to do that yourself.
451 In the default configuration only fatal errors are logged now.
452 You can change that in the <link linkend="DEBUG">debug section</link>
453 of the configuration file. You may also want to enable more verbose
454 logging until you verified that the new &my-app; version is working
461 Three other config file settings are now off by default:
462 <link linkend="enable-remote-toggle">enable-remote-toggle</link>,
463 <link linkend="enable-remote-http-toggle">enable-remote-http-toggle</link>,
464 and <link linkend="enable-edit-actions">enable-edit-actions</link>.
465 If you use or want these, you will need to explicitly enable them, and
466 be aware of the security issues involved.
473 What constitutes a <quote>default</quote> configuration has changed,
474 and you may want to review which actions are <quote>on</quote> by
475 default. This is primarily a matter of emphasis, but some features
476 you may have been used to, may now be <quote>off</quote> by default.
477 There are also a number of new actions and filters you may want to
478 consider, most of which are not fully incorporated into the default
479 settings as yet (see above).
486 The default actions setting is now <literal>Cautious</literal>. Previous
487 releases had a default setting of <literal>Medium</literal>. Experienced
488 users may want to adjust this, as it is fairly conservative by &my-app;
489 standards and past practices. See <ulink
490 url="http://config.privoxy.org/edit-actions-list?f=default">
491 http://config.privoxy.org/edit-actions-list?f=default</ulink>. New users
492 should try the default settings for a while before turning up the volume.
498 The default setting has filtering turned <emphasis>off</emphasis>, which
499 subsequently means that compression is <emphasis>on</emphasis>. Remember
500 that filtering does not work on compressed pages, so if you use, or want to
501 use, filtering, you will need to force compression off. Example:
505 { +<link linkend="filter">filter</link>{google} +<link linkend="prevent-compression">prevent-compression</link> }
509 Or if you use a number of filters, or filter many sites, you may just want
510 to turn off compression for all sites in
511 <filename>default.action</filename> (or
512 <filename>user.action</filename>).
519 Also, <link linkend="SESSION-COOKIES-ONLY">session-cookies-only</link> is
520 off by default now. If you've liked this feature in the past, you may want
521 to turn it back on in <filename>user.action</filename> now.
528 Some installers may not automatically start
529 <application>Privoxy</application> after installation.
540 <!-- ~~~~~ New section ~~~~~ -->
541 <sect1 id="quickstart"><title>Quickstart to Using Privoxy</title>
547 Install <application>Privoxy</application>. See the <link
548 linkend="installation">Installation Section</link> below for platform specific
555 Advanced users and those who want to offer <application>Privoxy</application>
556 service to more than just their local machine should check the <link
557 linkend="config">main config file</link>, especially the <link
558 linkend="access-control">security-relevant</link> options. These are
565 Start <application>Privoxy</application>, if the installation program has
566 not done this already (may vary according to platform). See the section
567 <link linkend="startup">Starting <application>Privoxy</application></link>.
573 Set your browser to use <application>Privoxy</application> as HTTP and
574 HTTPS (SSL) <ulink url="http://en.wikipedia.org/wiki/Proxy_server">proxy</ulink>
575 by setting the proxy configuration for address of
576 <literal>127.0.0.1</literal> and port <literal>8118</literal>.
577 <emphasis>DO NOT</emphasis> activate proxying for <literal>FTP</literal> or
578 any protocols besides HTTP and HTTPS (SSL) unless you intend to prevent your
579 browser from using these protocols.
585 Flush your browser's disk and memory caches, to remove any cached ad images.
586 If using <application>Privoxy</application> to manage
587 <ulink url="http://en.wikipedia.org/wiki/Browser_cookie">cookies</ulink>,
588 you should remove any currently stored cookies too.
594 A default installation should provide a reasonable starting point for
595 most. There will undoubtedly be occasions where you will want to adjust the
596 configuration, but that can be dealt with as the need arises. Little
597 to no initial configuration is required in most cases, you may want
599 <ulink url="config.html#ENABLE-EDIT-ACTIONS">web-based action editor</ulink> though.
600 Be sure to read the warnings first.
603 See the <link linkend="configuration">Configuration section</link> for more
604 configuration options, and how to customize your installation.
605 You might also want to look at the <link
606 linkend="quickstart-ad-blocking">next section</link> for a quick
607 introduction to how <application>Privoxy</application> blocks ads and
614 If you experience ads that slip through, innocent images that are
615 blocked, or otherwise feel the need to fine-tune
616 <application>Privoxy's</application> behavior, take a look at the <link
617 linkend="actions-file">actions files</link>. As a quick start, you might
618 find the <link linkend="act-examples">richly commented examples</link>
619 helpful. You can also view and edit the actions files through the <ulink
620 url="http://config.privoxy.org">web-based user interface</ulink>. The
621 Appendix <quote><link linkend="actionsanat">Troubleshooting: Anatomy of an
622 Action</link></quote> has hints on how to understand and debug actions that
623 <quote>misbehave</quote>.
629 Please see the section <link linkend="contact">Contacting the
630 Developers</link> on how to report bugs, problems with websites or to get
637 Now enjoy surfing with enhanced control, comfort and privacy!
645 <!-- ~~~~~ New section ~~~~~ -->
647 <sect2 id="quickstart-ad-blocking">
648 <title>Quickstart to Ad Blocking</title>
650 NOTE: This section is deliberately redundant for those that don't
651 want to read the whole thing (which is getting lengthy).
654 Ad blocking is but one of <application>Privoxy's</application>
655 array of features. Many of these features are for the technically minded advanced
656 user. But, ad and banner blocking is surely common ground for everybody.
659 This section will provide a quick summary of ad blocking so
660 you can get up to speed quickly without having to read the more extensive
661 information provided below, though this is highly recommended.
664 First a bit of a warning ... blocking ads is much like blocking SPAM: the
665 more aggressive you are about it, the more likely you are to block
666 things that were not intended. And the more likely that some things
667 may not work as intended. So there is a trade off here. If you want
668 extreme ad free browsing, be prepared to deal with more
669 <quote>problem</quote> sites, and to spend more time adjusting the
670 configuration to solve these unintended consequences. In short, there is
671 not an easy way to eliminate <emphasis>all</emphasis> ads. Either take
672 the easy way and settle for <emphasis>most</emphasis> ads blocked with the
673 default configuration, or jump in and tweak it for your personal surfing
674 habits and preferences.
677 Secondly, a brief explanation of <application>Privoxy's </application>
678 <quote>actions</quote>. <quote>Actions</quote> in this context, are
679 the directives we use to tell <application>Privoxy</application> to perform
680 some task relating to HTTP transactions (i.e. web browsing). We tell
681 <application>Privoxy</application> to take some <quote>action</quote>. Each
682 action has a unique name and function. While there are many potential
683 <application>actions</application> in <application>Privoxy's</application>
684 arsenal, only a few are used for ad blocking. <link
685 linkend="actions">Actions</link>, and <link linkend="actions-file">action
686 configuration files</link>, are explained in depth below.
689 Actions are specified in <application>Privoxy's</application> configuration,
690 followed by one or more URLs to which the action should apply. URLs
691 can actually be URL type <link linkend="af-patterns">patterns</link> that use
692 wildcards so they can apply potentially to a range of similar URLs. The
693 actions, together with the URL patterns are called a section.
696 When you connect to a website, the full URL will either match one or more
697 of the sections as defined in <application>Privoxy's</application> configuration,
698 or not. If so, then <application>Privoxy</application> will perform the
699 respective actions. If not, then nothing special happens. Furthermore, web
700 pages may contain embedded, secondary URLs that your web browser will
701 use to load additional components of the page, as it parses the
702 original page's HTML content. An ad image for instance, is just an URL
703 embedded in the page somewhere. The image itself may be on the same server,
704 or a server somewhere else on the Internet. Complex web pages will have many
705 such embedded URLs. &my-app; can deal with each URL individually, so, for
706 instance, the main page text is not touched, but images from such-and-such
711 The most important actions for basic ad blocking are: <literal><link
712 linkend="block">block</link></literal>, <literal><link
713 linkend="handle-as-image">handle-as-image</link></literal>,
715 linkend="handle-as-empty-document">handle-as-empty-document</link></literal>,and
716 <literal><link linkend="set-image-blocker">set-image-blocker</link></literal>:
724 <literal><link linkend="block">block</link></literal> - this is perhaps
725 the single most used action, and is particularly important for ad blocking.
726 This action stops any contact between your browser and any URL patterns
727 that match this action's configuration. It can be used for blocking ads,
728 but also anything that is determined to be unwanted. By itself, it simply
729 stops any communication with the remote server and sends
730 <application>Privoxy</application>'s own built-in BLOCKED page instead to
731 let you now what has happened (with some exceptions, see below).
737 <literal><link linkend="handle-as-image">handle-as-image</link></literal> -
738 tells <application>Privoxy</application> to treat this URL as an image.
739 <application>Privoxy</application>'s default configuration already does this
740 for all common image types (e.g. GIF), but there are many situations where this
741 is not so easy to determine. So we'll force it in these cases. This is particularly
742 important for ad blocking, since only if we know that it's an image of
743 some kind, can we replace it with an image of our choosing, instead of the
744 <application>Privoxy</application> BLOCKED page (which would only result in
745 a <quote>broken image</quote> icon). There are some limitations to this
746 though. For instance, you can't just brute-force an image substitution for
747 an entire HTML page in most situations.
753 <literal><link linkend="handle-as-empty-document">handle-as-empty-document</link></literal> -
754 sends an empty document instead of <application>Privoxy's</application>
755 normal BLOCKED HTML page. This is useful for file types that are neither
756 HTML nor images, such as blocking JavaScript files.
763 linkend="set-image-blocker">set-image-blocker</link></literal> - tells
764 <application>Privoxy</application> what to display in place of an ad image that
765 has hit a block rule. For this to come into play, the URL must match a
766 <literal><link linkend="block">block</link></literal> action somewhere in the
767 configuration, <emphasis>and</emphasis>, it must also match an
768 <literal><link linkend="handle-as-image">handle-as-image</link></literal> action.
771 The configuration options on what to display instead of the ad are:
775 <emphasis>pattern</emphasis> - a checkerboard pattern, so that an ad
776 replacement is obvious. This is the default.
781 <emphasis>blank</emphasis> - A very small empty GIF image is displayed.
782 This is the so-called <quote>invisible</quote> configuration option.
787 <emphasis>http://<URL></emphasis> - A redirect to any image anywhere
788 of the user's choosing (advanced usage).
797 Advanced users will eventually want to explore &my-app;
798 <literal><link linkend="filter">filters</link></literal> as well. Filters
799 are very different from <literal><link
800 linkend="block">blocks</link></literal>.
801 A <quote>block</quote> blocks a site, page, or unwanted contented. Filters
802 are a way of filtering or modifying what is actually on the page. An example
803 filter usage: a text replacement of <quote>no-no</quote> for
804 <quote>nasty-word</quote>. That is a very simple example. This process can be
805 used for ad blocking, but it is more in the realm of advanced usage and has
806 some pitfalls to be wary off.
810 The quickest way to adjust any of these settings is with your browser through
811 the special <application>Privoxy</application> editor at <ulink
812 url="http://config.privoxy.org/show-status">http://config.privoxy.org/show-status</ulink>
813 (shortcut: <ulink url="http://p.p/">http://p.p/show-status</ulink>). This
814 is an internal page, and does not require Internet access.
818 Note that as of <application>Privoxy</application> 3.0.7 beta the
819 action editor is disabled by default. Check the
820 <ulink url="config.html#ENABLE-EDIT-ACTIONS">enable-edit-actions
821 section in the configuration file</ulink> to learn why and in which
822 cases it's safe to enable again.
826 If you decided to enable the action editor, select the appropriate
827 <quote>actions</quote> file, and click
828 <quote><guibutton>Edit</guibutton></quote>. It is best to put personal or
829 local preferences in <filename>user.action</filename> since this is not
830 meant to be overwritten during upgrades, and will over-ride the settings in
831 other files. Here you can insert new <quote>actions</quote>, and URLs for ad
832 blocking or other purposes, and make other adjustments to the configuration.
833 <application>Privoxy</application> will detect these changes automatically.
837 A quick and simple step by step example:
845 Right click on the ad image to be blocked, then select
846 <quote><guimenuitem>Copy Link Location</guimenuitem></quote> from the
854 url="http://config.privoxy.org/show-status">http://config.privoxy.org/show-status</ulink>
859 Find <filename>user.action</filename> in the top section, and click
860 on <quote><guibutton>Edit</guibutton></quote>:
863 <!-- image of editor and actions files selections -->
865 <figure pgwide="0" float="0"><title>Actions Files in Use</title>
868 <imagedata fileref="files-in-use.jpg" format="jpg">
871 <phrase>[ Screenshot of Actions Files in Use ]</phrase>
880 You should have a section with only
881 <literal><link linkend="block">block</link></literal> listed under
882 <quote>Actions:</quote>.
883 If not, click a <quote><guibutton>Insert new section below</guibutton></quote>
884 button, and in the new section that just appeared, click the
885 <guibutton>Edit</guibutton> button right under the word <quote>Actions:</quote>.
886 This will bring up a list of all actions. Find
887 <literal><link linkend="block">block</link></literal> near the top, and click
888 in the <quote>Enabled</quote> column, then <quote><guibutton>Submit</guibutton></quote>
894 Now, in the <literal><link linkend="block">block</link></literal> actions section,
895 click the <quote><guibutton>Add</guibutton></quote> button, and paste the URL the
896 browser got from <quote><guimenuitem>Copy Link Location</guimenuitem></quote>.
897 Remove the <literal>http://</literal> at the beginning of the URL. Then, click
898 <quote><guibutton>Submit</guibutton></quote> (or
899 <quote><guibutton>OK</guibutton></quote> if in a pop-up window).
904 Now go back to the original page, and press <keycap>SHIFT-Reload</keycap>
905 (or flush all browser caches). The image should be gone now.
913 This is a very crude and simple example. There might be good reasons to use a
914 wildcard pattern match to include potentially similar images from the same
915 site. For a more extensive explanation of <quote>patterns</quote>, and
916 the entire actions concept, see <link linkend="actions-file">the Actions
921 For advanced users who want to hand edit their config files, you might want
922 to now go to the <link linkend="act-examples">Actions Files Tutorial</link>.
923 The ideas explained therein also apply to the web-based editor.
926 There are also various
927 <link linkend="filter">filters</link> that can be used for ad blocking
928 (filters are a special subset of actions). These
929 fall into the <quote>advanced</quote> usage category, and are explained in
930 depth in later sections.
937 <!-- ~ End section ~ -->
940 <!-- ~~~~~ New section ~~~~~ -->
942 <title>Starting Privoxy</title>
944 Before launching <application>Privoxy</application> for the first time, you
945 will want to configure your browser(s) to use
946 <application>Privoxy</application> as a HTTP and HTTPS (SSL)
947 <ulink url="http://en.wikipedia.org/wiki/Proxy_server">proxy</ulink>. The default is
948 127.0.0.1 (or localhost) for the proxy address, and port 8118 (earlier versions
949 used port 8000). This is the one configuration step <emphasis>that must be done
953 Please note that <application>Privoxy</application> can only proxy HTTP and
954 HTTPS traffic. It will not work with FTP or other protocols.
957 <!-- image of Mozilla Proxy configuration -->
959 <figure pgwide="0" float="0"><title>Proxy Configuration Showing
960 Mozilla/Netscape HTTP and HTTPS (SSL) Settings</title>
963 <imagedata fileref="proxy_setup.jpg" format="jpg">
966 <phrase>[ Screenshot of Mozilla Proxy Configuration ]</phrase>
974 With <application>Firefox</application>, this is typically set under:
978 <guibutton>Tools</guibutton> -> <guibutton>Options</guibutton> -> <guibutton>Advanced</guibutton> -> <guibutton>Network</guibutton> -><guibutton>Connection</guibutton> -> <guibutton>Settings</guibutton>
983 Or optionally on some platforms:
987 <guibutton>Edit</guibutton> -> <guibutton>Preferences</guibutton> -> <guibutton>General</guibutton> -> <guibutton>Connection Settings</guibutton> -> <guibutton>Manual Proxy Configuration</guibutton>
993 With <application>Netscape</application> (and
994 <application>Mozilla</application>), this can be set under:
999 <!-- Mix ascii and gui art, something for everybody -->
1000 <!-- spacing on this is tricky -->
1001 <guibutton>Edit</guibutton> -> <guibutton>Preferences</guibutton> -> <guibutton>Advanced</guibutton> -> <guibutton>Proxies</guibutton> -> <guibutton>HTTP Proxy</guibutton>
1006 For <application>Internet Explorer v.5-7</application>:
1010 <guibutton>Tools</guibutton> -> <guibutton>Internet Options</guibutton> -> <guibutton>Connections</guibutton> -> <guibutton>LAN Settings</guibutton>
1014 Then, check <quote>Use Proxy</quote> and fill in the appropriate info
1015 (Address: 127.0.0.1, Port: 8118). Include HTTPS (SSL), if you want HTTPS
1016 proxy support too (sometimes labeled <quote>Secure</quote>). Make sure any
1017 checkboxes like <quote>Use the same proxy server for all protocols</quote> is
1018 <emphasis>UNCHECKED</emphasis>. You want only HTTP and HTTPS (SSL)!
1021 <!-- image of IE Proxy configuration -->
1023 <figure pgwide="0" float="0"><title>Proxy Configuration Showing
1024 Internet Explorer HTTP and HTTPS (Secure) Settings</title>
1027 <imagedata fileref="proxy2.jpg" format="jpg">
1030 <phrase>[ Screenshot of IE Proxy Configuration ]</phrase>
1038 After doing this, flush your browser's disk and memory caches to force a
1039 re-reading of all pages and to get rid of any ads that may be cached. Remove
1040 any <ulink url="http://en.wikipedia.org/wiki/Browser_cookie">cookies</ulink>,
1041 if you want <application>Privoxy</application> to manage that. You are now
1042 ready to start enjoying the benefits of using
1043 <application>Privoxy</application>!
1047 <application>Privoxy</application> itself is typically started by specifying the
1048 main configuration file to be used on the command line. If no configuration
1049 file is specified on the command line, <application>Privoxy</application>
1050 will look for a file named <filename>config</filename> in the current
1051 directory. Except on Win32 where it will try <filename>config.txt</filename>.
1054 <sect2 id="start-debian">
1055 <title>Debian</title>
1057 We use a script. Note that Debian typically starts &my-app; upon booting per
1058 default. It will use the file
1059 <filename>/etc/privoxy/config</filename> as its main configuration
1064 # /etc/init.d/privoxy start
1069 <sect2 id="start-freebsd">
1070 <title>FreeBSD and ElectroBSD</title>
1072 To start <application>Privoxy</application> upon booting, add
1073 "privoxy_enable='YES'" to <filename>/etc/rc.conf</filename>.
1074 <application>Privoxy</application> will use
1075 <filename>/usr/local/etc/privoxy/config</filename> as its main
1079 If you installed <application>Privoxy</application> into a jail, the
1080 paths above are relative to the jail root.
1083 To start <application>Privoxy</application> manually, run:
1087 # service privoxy onestart
1092 <sect2 id="start-windows">
1093 <title>Windows</title>
1095 Click on the &my-app; Icon to start <application>Privoxy</application>. If no configuration file is
1096 specified on the command line, <application>Privoxy</application> will look
1097 for a file named <filename>config.txt</filename>. Note that Windows will
1098 automatically start &my-app; when the system starts if you chose that option
1102 <application>Privoxy</application> can run with full Windows service functionality.
1103 On Windows only, the &my-app; program has two new command line arguments
1104 to install and uninstall &my-app; as a service. See the
1105 <link linkend="installation-pack-win">Windows Installation
1106 instructions</link> for details.
1110 <sect2 id="start-unices">
1111 <title>Generic instructions for Unix derivates (Solaris, NetBSD, HP-UX etc.)</title>
1113 Example Unix startup command:
1117 # /usr/sbin/privoxy --user privoxy /etc/privoxy/config
1121 Note that if you installed <application>Privoxy</application> through
1122 a package manager, the package will probably contain a platform-specific
1123 script or configuration file to start <application>Privoxy</application>
1128 <sect2 id="start-os2">
1131 During installation, <application>Privoxy</application> is configured to
1132 start automatically when the system restarts. You can start it manually by
1133 double-clicking on the <application>Privoxy</application> icon in the
1134 <application>Privoxy</application> folder.
1138 <sect2 id="start-macosx">
1139 <title>Mac OS X</title>
1141 After downloading the privoxy software, unzip the downloaded file by
1142 double-clicking on the zip file icon. Then, double-click on the
1143 installer package icon and follow the installation process.
1146 The privoxy service will automatically start after a successful
1147 installation. In addition, the privoxy service will automatically
1148 start every time your computer starts up.
1151 To prevent the privoxy service from automatically starting when your
1152 computer starts up, remove or rename the folder named
1153 /Library/StartupItems/Privoxy.
1156 A simple application named Privoxy Utility has been created which
1157 enables administrators to easily start and stop the privoxy service.
1160 In addition, the Privoxy Utility presents a simple way for
1161 administrators to edit the various privoxy config files. A method
1162 to uninstall the software is also available.
1165 An administrator username and password must be supplied in order for
1166 the Privoxy Utility to perform any of the tasks.
1174 See the section <link linkend="cmdoptions">Command line options</link> for
1178 must find a better place for this paragraph
1181 The included default configuration files should give a reasonable starting
1182 point. Most of the per site configuration is done in the
1183 <ulink url="actions-file.html"><quote>actions</quote></ulink> files. These are
1184 where various cookie actions are defined, ad and banner blocking, and other
1185 aspects of <application>Privoxy</application> configuration. There are several
1186 such files included, with varying levels of aggressiveness.
1190 You will probably want to keep an eye out for sites for which you may prefer
1191 persistent cookies, and add these to your actions configuration as needed. By
1192 default, most of these will be accepted only during the current browser
1193 session (aka <quote>session cookies</quote>), unless you add them to the
1194 configuration. If you want the browser to handle this instead, you will need
1195 to edit <filename>user.action</filename> (or through the web based interface)
1196 and disable this feature. If you use more than one browser, it would make
1197 more sense to let <application>Privoxy</application> handle this. In which
1198 case, the browser(s) should be set to accept all cookies.
1202 Another feature where you will probably want to define exceptions for trusted
1203 sites is the popup-killing (through <ulink
1204 url="actions-file.html#FILTER-POPUPS"><quote>+filter{popups}</quote></ulink>),
1205 because your favorite shopping, banking, or leisure site may need
1206 popups (explained below).
1210 <application>Privoxy</application> does not support all of the optional HTTP/1.1
1211 features yet. In the unlikely event that you experience inexplicable problems
1212 with browsers that use HTTP/1.1 per default
1213 (like <application>Mozilla</application> or recent versions of I.E.), you might
1214 try to force HTTP/1.0 compatibility. For Mozilla, look under <literal>Edit ->
1215 Preferences -> Debug -> Networking</literal>.
1216 Alternatively, set the <quote>+downgrade-http-version</quote> config option in
1217 <filename>default.action</filename> which will downgrade your browser's HTTP
1218 requests from HTTP/1.1 to HTTP/1.0 before processing them.
1222 After running <application>Privoxy</application> for a while, you can
1223 start to fine tune the configuration to suit your personal, or site,
1224 preferences and requirements. There are many, many aspects that can
1225 be customized. <quote>Actions</quote>
1226 can be adjusted by pointing your browser to
1227 <ulink url="http://config.privoxy.org/">http://config.privoxy.org/</ulink>
1228 (shortcut: <ulink url="http://p.p/">http://p.p/</ulink>),
1229 and then follow the link to <quote>View & Change the Current Configuration</quote>.
1230 (This is an internal page and does not require Internet access.)
1234 In fact, various aspects of <application>Privoxy</application>
1235 configuration can be viewed from this page, including
1236 current configuration parameters, source code version numbers,
1237 the browser's request headers, and <quote>actions</quote> that apply
1238 to a given URL. In addition to the actions file
1239 editor mentioned above, <application>Privoxy</application> can also
1240 be turned <quote>on</quote> and <quote>off</quote> (toggled) from this page.
1244 If you encounter problems, try loading the page without
1245 <application>Privoxy</application>. If that helps, enter the URL where
1246 you have the problems into <ulink url="http://p.p/show-url-info">the browser
1247 based rule tracing utility</ulink>. See which rules apply and why, and
1248 then try turning them off for that site one after the other, until the problem
1249 is gone. When you have found the culprit, you might want to turn the rest on
1254 If the above paragraph sounds gibberish to you, you might want to <link
1255 linkend="actions-file">read more about the actions concept</link>
1256 or even dive deep into the <link linkend="actionsanat">Appendix
1261 If you can't get rid of the problem at all, think you've found a bug in
1262 Privoxy, want to propose a new feature or smarter rules, please see the
1263 section <link linkend="contact"><quote>Contacting the
1264 Developers</quote></link> below.
1269 <!-- ~~~~~ New section ~~~~~ -->
1270 <sect2 id="cmdoptions">
1271 <title>Command Line Options</title>
1273 <application>Privoxy</application> may be invoked with the following
1274 command-line options:
1282 <emphasis>--config-test</emphasis>
1285 Exit after loading the configuration files before binding to
1286 the listen address. The exit code signals whether or not the
1287 configuration files have been successfully loaded.
1290 If the exit code is 1, at least one of the configuration files
1291 is invalid, if it is 0, all the configuration files have been
1292 successfully loaded (but may still contain errors that can
1293 currently only be detected at run time).
1296 This option doesn't affect the log setting, combination with
1297 <emphasis>--no-daemon</emphasis> is recommended if a configured
1298 log file shouldn't be used.
1303 <emphasis>--version</emphasis>
1306 Print version info and exit. Unix only.
1311 <emphasis>--help</emphasis>
1314 Print short usage info and exit. Unix only.
1319 <emphasis>--no-daemon</emphasis>
1322 Don't become a daemon, i.e. don't fork and become process group
1323 leader, and don't detach from controlling tty. Unix only.
1328 <emphasis>--pidfile FILE</emphasis>
1331 On startup, write the process ID to <emphasis>FILE</emphasis>. Delete the
1332 <emphasis>FILE</emphasis> on exit. Failure to create or delete the
1333 <emphasis>FILE</emphasis> is non-fatal. If no <emphasis>FILE</emphasis>
1334 option is given, no PID file will be used. Unix only.
1339 <emphasis>--user USER[.GROUP]</emphasis>
1342 After (optionally) writing the PID file, assume the user ID of
1343 <emphasis>USER</emphasis>, and if included the GID of GROUP. Exit if the
1344 privileges are not sufficient to do so. Unix only.
1349 <emphasis>--chroot</emphasis>
1352 Before changing to the user ID given in the <emphasis>--user</emphasis> option,
1353 chroot to that user's home directory, i.e. make the kernel pretend to the &my-app;
1354 process that the directory tree starts there. If set up carefully, this can limit
1355 the impact of possible vulnerabilities in &my-app; to the files contained in that hierarchy.
1361 <emphasis>--pre-chroot-nslookup hostname</emphasis>
1364 Specifies a hostname (for example www.privoxy.org) to look up before doing a chroot.
1365 On some systems, initializing the resolver library involves reading config files from
1366 /etc and/or loading additional shared libraries from /lib.
1367 On these systems, doing a hostname lookup before the chroot reduces
1368 the number of files that must be copied into the chroot tree.
1371 For fastest startup speed, a good value is a hostname that is not in /etc/hosts but that
1372 your local name server (listed in /etc/resolv.conf) can resolve without recursion
1373 (that is, without having to ask any other name servers). The hostname need not exist,
1374 but if it doesn't, an error message (which can be ignored) will be output.
1380 <emphasis>configfile</emphasis>
1383 If no <emphasis>configfile</emphasis> is included on the command line,
1384 <application>Privoxy</application> will look for a file named
1385 <quote>config</quote> in the current directory (except on Win32
1386 where it will look for <quote>config.txt</quote> instead). Specify
1387 full path to avoid confusion. If no config file is found,
1388 <application>Privoxy</application> will fail to start.
1396 On <application>MS Windows</application> only there are two additional
1397 command-line options to allow <application>Privoxy</application> to install and
1398 run as a <emphasis>service</emphasis>. See the
1399 <link linkend="installation-pack-win">Window Installation section</link>
1407 <!-- ~ End section ~ -->
1410 <!-- ~~~~~ New section ~~~~~ -->
1411 <sect1 id="configuration"><title>Privoxy Configuration</title>
1413 All <application>Privoxy</application> configuration is stored
1414 in text files. These files can be edited with a text editor.
1415 Many important aspects of <application>Privoxy</application> can
1416 also be controlled easily with a web browser.
1420 <!-- ~~~~~ New section ~~~~~ -->
1423 <title>Controlling Privoxy with Your Web Browser</title>
1425 <application>Privoxy</application>'s user interface can be reached through the special
1426 URL <ulink url="http://config.privoxy.org/">http://config.privoxy.org/</ulink>
1427 (shortcut: <ulink url="http://p.p/">http://p.p/</ulink>),
1428 which is a built-in page and works without Internet access.
1429 You will see the following section:
1433 <!-- Needs to be put in a table and colorized -->
1436 <bridgehead renderas="sect2"> Privoxy Menu</bridgehead>
1440 ▪ <ulink url="http://config.privoxy.org/show-status">View & change the current configuration</ulink>
1443 ▪ <ulink url="http://config.privoxy.org/show-version">View the source code version numbers</ulink>
1446 ▪ <ulink url="http://config.privoxy.org/show-request">View the request headers.</ulink>
1449 ▪ <ulink url="http://config.privoxy.org/show-url-info">Look up which actions apply to a URL and why</ulink>
1452 ▪ <ulink url="http://config.privoxy.org/toggle">Toggle Privoxy on or off</ulink>
1455 ▪ <ulink
1456 url="http://www.privoxy.org/&p-version;/user-manual/">Documentation</ulink>
1464 This should be self-explanatory. Note the first item leads to an editor for the
1465 <link linkend="actions-file">actions files</link>, which is where the ad, banner,
1466 cookie, and URL blocking magic is configured as well as other advanced features of
1467 <application>Privoxy</application>. This is an easy way to adjust various
1468 aspects of <application>Privoxy</application> configuration. The actions
1469 file, and other configuration files, are explained in detail below.
1473 <quote>Toggle Privoxy On or Off</quote> is handy for sites that might
1474 have problems with your current actions and filters. You can in fact use
1475 it as a test to see whether it is <application>Privoxy</application>
1476 causing the problem or not. <application>Privoxy</application> continues
1477 to run as a proxy in this case, but all manipulation is disabled, i.e.
1478 <application>Privoxy</application> acts like a normal forwarding proxy.
1482 Note that several of the features described above are disabled by default
1483 in <application>Privoxy</application> 3.0.7 beta and later.
1485 <ulink url="config.html">configuration file</ulink> to learn why
1486 and in which cases it's safe to enable them again.
1491 <!-- ~ End section ~ -->
1496 <!-- ~~~~~ New section ~~~~~ -->
1498 <sect2 id="confoverview">
1499 <title>Configuration Files Overview</title>
1501 For Unix, *BSD and Linux, all configuration files are located in
1502 <filename>/etc/privoxy/</filename> by default. For MS Windows, OS/2, and
1503 AmigaOS these are all in the same directory as the
1504 <application>Privoxy</application> executable. <![%p-not-stable;[ The name
1505 and number of configuration files has changed from previous versions, and is
1506 subject to change as development progresses.]]>
1510 The installed defaults provide a reasonable starting point, though
1511 some settings may be aggressive by some standards. For the time being, the
1512 principle configuration files are:
1520 The <link linkend="config">main configuration file</link> is named <filename>config</filename>
1521 on Linux, Unix, BSD, OS/2, and AmigaOS and <filename>config.txt</filename>
1522 on Windows. This is a required file.
1528 <filename>match-all.action</filename> is used to define which <quote>actions</quote>
1529 relating to banner-blocking, images, pop-ups, content modification, cookie handling
1530 etc should be applied by default. It should be the first actions file loaded.
1533 <filename>default.action</filename> defines many exceptions (both positive and negative)
1534 from the default set of actions that's configured in <filename>match-all.action</filename>.
1535 It should be the second actions file loaded and shouldn't be edited by the user.
1538 Multiple actions files may be defined in <filename>config</filename>. These
1539 are processed in the order they are defined. Local customizations and locally
1540 preferred exceptions to the default policies as defined in
1541 <filename>match-all.action</filename> (which you will most probably want
1542 to define sooner or later) are best applied in <filename>user.action</filename>,
1543 where you can preserve them across upgrades. The file isn't installed by all
1544 installers, but you can easily create it yourself with a text editor.
1547 There is also a web based editor that can be accessed from
1549 url="http://config.privoxy.org/show-status">http://config.privoxy.org/show-status</ulink>
1551 url="http://p.p/show-status">http://p.p/show-status</ulink>) for the
1552 various actions files.
1558 <quote>Filter files</quote> (the <link linkend="filter-file">filter
1559 file</link>) can be used to re-write the raw page content, including
1560 viewable text as well as embedded HTML and JavaScript, and whatever else
1561 lurks on any given web page. The filtering jobs are only pre-defined here;
1562 whether to apply them or not is up to the actions files.
1563 <filename>default.filter</filename> includes various filters made
1564 available for use by the developers. Some are much more intrusive than
1565 others, and all should be used with caution. You may define additional
1566 filter files in <filename>config</filename> as you can with
1567 actions files. We suggest <filename>user.filter</filename> for any
1568 locally defined filters or customizations.
1576 The syntax of the configuration and filter files may change between different
1577 Privoxy versions, unfortunately some enhancements cost backwards compatibility.
1578 <!-- Add link to documentation-->
1582 All files use the <quote><literal>#</literal></quote> character to denote a
1583 comment (the rest of the line will be ignored) and understand line continuation
1584 through placing a backslash ("<literal>\</literal>") as the very last character
1585 in a line. If the <literal>#</literal> is preceded by a backslash, it looses
1586 its special function. Placing a <literal>#</literal> in front of an otherwise
1587 valid configuration line to prevent it from being interpreted is called "commenting
1588 out" that line. Blank lines are ignored.
1592 The actions files and filter files
1593 can use Perl style <link linkend="regex">regular expressions</link> for
1594 maximum flexibility.
1598 After making any changes, there is no need to restart
1599 <application>Privoxy</application> in order for the changes to take
1600 effect. <application>Privoxy</application> detects such changes
1601 automatically. Note, however, that it may take one or two additional
1602 requests for the change to take effect. When changing the listening address
1603 of <application>Privoxy</application>, these <quote>wake up</quote> requests
1604 must obviously be sent to the <emphasis>old</emphasis> listening address.
1609 While under development, the configuration content is subject to change.
1610 The below documentation may not be accurate by the time you read this.
1611 Also, what constitutes a <quote>default</quote> setting, may change, so
1612 please check all your configuration files on important issues.
1618 <!-- ~ End section ~ -->
1621 <!-- ~~~~~~~~ New section Header ~~~~~~~~~ -->
1623 <!-- **************************************************** -->
1624 <!-- Include config.sgml here -->
1625 <!-- This is where the entire config file is detailed. -->
1627 <!-- end include -->
1630 <!-- ~ End section ~ -->
1634 <!-- ~~~~~~~~ New section Header ~~~~~~~~~ -->
1636 <sect1 id="actions-file"><title>Actions Files</title>
1640 XXX: similar descriptions are in the Configuration Files sections.
1641 We should only describe them at one place.
1644 The actions files are used to define what <emphasis>actions</emphasis>
1645 <application>Privoxy</application> takes for which URLs, and thus determines
1646 how ad images, cookies and various other aspects of HTTP content and
1647 transactions are handled, and on which sites (or even parts thereof).
1648 There are a number of such actions, with a wide range of functionality.
1649 Each action does something a little different.
1650 These actions give us a veritable arsenal of tools with which to exert
1651 our control, preferences and independence. Actions can be combined so that
1652 their effects are aggregated when applied against a given set of URLs.
1656 are three action files included with <application>Privoxy</application> with
1663 <filename>match-all.action</filename> - is used to define which
1664 <quote>actions</quote> relating to banner-blocking, images, pop-ups,
1665 content modification, cookie handling etc should be applied by default.
1666 It should be the first actions file loaded
1671 <filename>default.action</filename> - defines many exceptions (both
1672 positive and negative) from the default set of actions that's configured
1673 in <filename>match-all.action</filename>. It is a set of rules that should
1674 work reasonably well as-is for most users. This file is only supposed to
1675 be edited by the developers. It should be the second actions file loaded.
1680 <filename>user.action</filename> - is intended to be for local site
1681 preferences and exceptions. As an example, if your ISP or your bank
1682 has specific requirements, and need special handling, this kind of
1683 thing should go here. This file will not be upgraded.
1688 <guibutton>Edit</guibutton> <guibutton>Set to Cautious</guibutton> <guibutton>Set to Medium</guibutton> <guibutton>Set to Advanced</guibutton>
1691 These have increasing levels of aggressiveness <emphasis>and have no
1692 influence on your browsing unless you select them explicitly in the
1693 editor</emphasis>. A default installation should be pre-set to
1694 <literal>Cautious</literal>. New users should try this for a while before
1695 adjusting the settings to more aggressive levels. The more aggressive
1696 the settings, then the more likelihood there is of problems such as sites
1697 not working as they should.
1700 The <guibutton>Edit</guibutton> button allows you to turn each
1701 action on/off individually for fine-tuning. The <guibutton>Cautious</guibutton>
1702 button changes the actions list to low/safe settings which will activate
1703 ad blocking and a minimal set of &my-app;'s features, and subsequently
1704 there will be less of a chance for accidental problems. The
1705 <guibutton>Medium</guibutton> button sets the list to a medium level of
1706 other features and a low level set of privacy features. The
1707 <guibutton>Advanced</guibutton> button sets the list to a high level of
1708 ad blocking and medium level of privacy. See the chart below. The latter
1709 three buttons over-ride any changes via with the
1710 <guibutton>Edit</guibutton> button. More fine-tuning can be done in the
1711 lower sections of this internal page.
1714 While the actions file editor allows to enable these settings in all
1715 actions files, they are only supposed to be enabled in the first one
1716 to make sure you don't unintentionally overrule earlier rules.
1719 The default profiles, and their associated actions, as pre-defined in
1720 <filename>default.action</filename> are:
1723 <table frame=all><title>Default Configurations</title>
1724 <tgroup cols=4 align=left colsep=1 rowsep=1>
1725 <colspec colname=c1>
1726 <colspec colname=c2>
1727 <colspec colname=c3>
1728 <colspec colname=c4>
1731 <entry>Feature</entry>
1732 <entry>Cautious</entry>
1733 <entry>Medium</entry>
1734 <entry>Advanced</entry>
1739 <!-- <entry>f1</entry> -->
1740 <!-- <entry>f2</entry> -->
1741 <!-- <entry>f3</entry> -->
1742 <!-- <entry>f4</entry> -->
1748 <entry>Ad-blocking Aggressiveness</entry>
1749 <entry>medium</entry>
1755 <entry>Ad-filtering by size</entry>
1762 <entry>Ad-filtering by link</entry>
1768 <entry>Pop-up killing</entry>
1769 <entry>blocks only</entry>
1770 <entry>blocks only</entry>
1771 <entry>blocks only</entry>
1775 <entry>Privacy Features</entry>
1777 <entry>medium</entry>
1778 <entry>medium/high</entry>
1782 <entry>Cookie handling</entry>
1784 <entry>session-only</entry>
1789 <entry>Referer forging</entry>
1796 <entry>GIF de-animation</entry>
1803 <entry>Fast redirects</entry>
1810 <entry>HTML taming</entry>
1817 <entry>JavaScript taming</entry>
1824 <entry>Web-bug killing</entry>
1831 <entry>Image tag reordering</entry>
1847 The list of actions files to be used are defined in the main configuration
1848 file, and are processed in the order they are defined (e.g.
1849 <filename>default.action</filename> is typically processed before
1850 <filename>user.action</filename>). The content of these can all be viewed and
1852 url="http://config.privoxy.org/show-status">http://config.privoxy.org/show-status</ulink>.
1853 The over-riding principle when applying actions, is that the last action that
1854 matches a given URL wins. The broadest, most general rules go first
1855 (defined in <filename>default.action</filename>),
1856 followed by any exceptions (typically also in
1857 <filename>default.action</filename>), which are then followed lastly by any
1858 local preferences (typically in <emphasis>user</emphasis><filename>.action</filename>).
1859 Generally, <filename>user.action</filename> has the last word.
1863 An actions file typically has multiple sections. If you want to use
1864 <quote>aliases</quote> in an actions file, you have to place the (optional)
1865 <link linkend="aliases">alias section</link> at the top of that file.
1866 Then comes the default set of rules which will apply universally to all
1867 sites and pages (be <emphasis>very careful</emphasis> with using such a
1868 universal set in <filename>user.action</filename> or any other actions file after
1869 <filename>default.action</filename>, because it will override the result
1870 from consulting any previous file). And then below that,
1871 exceptions to the defined universal policies. You can regard
1872 <filename>user.action</filename> as an appendix to <filename>default.action</filename>,
1873 with the advantage that it is a separate file, which makes preserving your
1874 personal settings across <application>Privoxy</application> upgrades easier.
1878 Actions can be used to block anything you want, including ads, banners, or
1879 just some obnoxious URL whose content you would rather not see. Cookies can be accepted
1880 or rejected, or accepted only during the current browser session (i.e. not
1881 written to disk), content can be modified, some JavaScripts tamed, user-tracking
1882 fooled, and much more. See below for a <link linkend="actions">complete list
1886 <!-- ~~~~~ New section ~~~~~ -->
1888 <title>Finding the Right Mix</title>
1890 Note that some <link linkend="actions">actions</link>, like cookie suppression
1891 or script disabling, may render some sites unusable that rely on these
1892 techniques to work properly. Finding the right mix of actions is not always easy and
1893 certainly a matter of personal taste. And, things can always change, requiring
1894 refinements in the configuration. In general, it can be said that the more
1895 <quote>aggressive</quote> your default settings (in the top section of the
1896 actions file) are, the more exceptions for <quote>trusted</quote> sites you
1897 will have to make later. If, for example, you want to crunch all cookies per
1898 default, you'll have to make exceptions from that rule for sites that you
1899 regularly use and that require cookies for actually useful purposes, like maybe
1900 your bank, favorite shop, or newspaper.
1904 We have tried to provide you with reasonable rules to start from in the
1905 distribution actions files. But there is no general rule of thumb on these
1906 things. There just are too many variables, and sites are constantly changing.
1907 Sooner or later you will want to change the rules (and read this chapter again :).
1911 <!-- ~~~~~ New section ~~~~~ -->
1913 <title>How to Edit</title>
1915 The easiest way to edit the actions files is with a browser by
1916 using our browser-based editor, which can be reached from <ulink
1917 url="http://config.privoxy.org/show-status">http://config.privoxy.org/show-status</ulink>.
1918 Note: the config file option <link
1919 linkend="enable-edit-actions">enable-edit-actions</link> must be enabled for
1920 this to work. The editor allows both fine-grained control over every single
1921 feature on a per-URL basis, and easy choosing from wholesale sets of defaults
1922 like <quote>Cautious</quote>, <quote>Medium</quote> or
1923 <quote>Advanced</quote>. Warning: the <quote>Advanced</quote> setting is more
1924 aggressive, and will be more likely to cause problems for some sites.
1925 Experienced users only!
1929 If you prefer plain text editing to GUIs, you can of course also directly edit the
1930 the actions files with your favorite text editor. Look at
1931 <filename>default.action</filename> which is richly commented with many
1937 <sect2 id="actions-apply">
1938 <title>How Actions are Applied to Requests</title>
1940 Actions files are divided into sections. There are special sections,
1941 like the <quote><link linkend="aliases">alias</link></quote> sections which will
1942 be discussed later. For now let's concentrate on regular sections: They have a
1943 heading line (often split up to multiple lines for readability) which consist
1944 of a list of actions, separated by whitespace and enclosed in curly braces.
1945 Below that, there is a list of URL and tag patterns, each on a separate line.
1949 To determine which actions apply to a request, the URL of the request is
1950 compared to all URL patterns in each <quote>action file</quote>.
1951 Every time it matches, the list of applicable actions for the request is
1952 incrementally updated, using the heading of the section in which the
1953 pattern is located. The same is done again for tags and tag patterns later on.
1957 If multiple applying sections set the same action differently,
1958 the last match wins. If not, the effects are aggregated.
1959 E.g. a URL might match a regular section with a heading line of <literal>{
1960 +<link linkend="handle-as-image">handle-as-image</link> }</literal>,
1961 then later another one with just <literal>{
1962 +<link linkend="block">block</link> }</literal>, resulting
1963 in <emphasis>both</emphasis> actions to apply. And there may well be
1964 cases where you will want to combine actions together. Such a section then
1970 { +<literal>handle-as-image</literal> +<literal>block{Banner ads.}</literal> }
1971 # Block these as if they were images. Send no block page.
1973 media.example.com/.*banners
1974 .example.com/images/ads/</screen>
1978 You can trace this process for URL patterns and any given URL by visiting <ulink
1979 url="http://config.privoxy.org/show-url-info">http://config.privoxy.org/show-url-info</ulink>.
1983 Examples and more detail on this is provided in the Appendix, <link linkend="ACTIONSANAT">
1984 Troubleshooting: Anatomy of an Action</link> section.
1988 <!-- ~~~~~ New section ~~~~~ -->
1989 <sect2 id="af-patterns">
1990 <title>Patterns</title>
1992 As mentioned, <application>Privoxy</application> uses <quote>patterns</quote>
1993 to determine what <emphasis>actions</emphasis> might apply to which sites and
1994 pages your browser attempts to access. These <quote>patterns</quote> use wild
1995 card type <emphasis>pattern</emphasis> matching to achieve a high degree of
1996 flexibility. This allows one expression to be expanded and potentially match
1997 against many similar patterns.
2001 Generally, an URL pattern has the form
2002 <literal><host><port>/<path></literal>, where the
2003 <literal><host></literal>, the <literal><port></literal>
2004 and the <literal><path></literal> are optional. (This is why the special
2005 <literal>/</literal> pattern matches all URLs). Note that the protocol
2006 portion of the URL pattern (e.g. <literal>http://</literal>) should
2007 <emphasis>not</emphasis> be included in the pattern. This is assumed already!
2010 The pattern matching syntax is different for the host and path parts of
2011 the URL. The host part uses a simple globbing type matching technique,
2012 while the path part uses more flexible
2013 <ulink url="http://en.wikipedia.org/wiki/Regular_expressions"><quote>Regular
2014 Expressions</quote></ulink> (POSIX 1003.2).
2017 The port part of a pattern is a decimal port number preceded by a colon
2018 (<literal>:</literal>). If the host part contains a numerical IPv6 address,
2019 it has to be put into angle brackets
2020 (<literal><</literal>, <literal>></literal>).
2025 <term><literal>www.example.com/</literal></term>
2028 is a host-only pattern and will match any request to <literal>www.example.com</literal>,
2029 regardless of which document on that server is requested. So ALL pages in
2030 this domain would be covered by the scope of this action. Note that a
2031 simple <literal>example.com</literal> is different and would NOT match.
2036 <term><literal>www.example.com</literal></term>
2039 means exactly the same. For host-only patterns, the trailing <literal>/</literal> may
2045 <term><literal>www.example.com/index.html</literal></term>
2048 matches all the documents on <literal>www.example.com</literal>
2049 whose name starts with <literal>/index.html</literal>.
2054 <term><literal>www.example.com/index.html$</literal></term>
2057 matches only the single document <literal>/index.html</literal>
2058 on <literal>www.example.com</literal>.
2063 <term><literal>/index.html$</literal></term>
2066 matches the document <literal>/index.html</literal>, regardless of the domain,
2067 i.e. on <emphasis>any</emphasis> web server anywhere.
2072 <term><literal>/</literal></term>
2075 Matches any URL because there's no requirement for either the
2076 domain or the path to match anything.
2081 <term><literal>:8000/</literal></term>
2084 Matches any URL pointing to TCP port 8000.
2089 <term><literal>10.0.0.1/</literal></term>
2092 Matches any URL with the host address <literal>10.0.0.1</literal>.
2093 (Note that the real URL uses plain brackets, not angle brackets.)
2098 <term><literal><2001:db8::1>/</literal></term>
2101 Matches any URL with the host address <literal>2001:db8::1</literal>.
2102 (Note that the real URL uses plain brackets, not angle brackets.)
2107 <term><literal>index.html</literal></term>
2110 matches nothing, since it would be interpreted as a domain name and
2111 there is no top-level domain called <literal>.html</literal>. So its
2119 <!-- ~~~~~ New section ~~~~~ -->
2120 <sect3 id="host-pattern"><title>The Host Pattern</title>
2123 The matching of the host part offers some flexible options: if the
2124 host pattern starts or ends with a dot, it becomes unanchored at that end.
2125 The host pattern is often referred to as domain pattern as it is usually
2126 used to match domain names and not IP addresses.
2132 <term><literal>.example.com</literal></term>
2135 matches any domain with first-level domain <literal>com</literal>
2136 and second-level domain <literal>example</literal>.
2137 For example <literal>www.example.com</literal>,
2138 <literal>example.com</literal> and <literal>foo.bar.baz.example.com</literal>.
2139 Note that it wouldn't match if the second-level domain was <literal>another-example</literal>.
2144 <term><literal>www.</literal></term>
2147 matches any domain that <emphasis>STARTS</emphasis> with
2148 <literal>www.</literal> (It also matches the domain
2149 <literal>www</literal> but most of the time that doesn't matter.)
2154 <term><literal>.example.</literal></term>
2157 matches any domain that <emphasis>CONTAINS</emphasis> <literal>.example.</literal>.
2158 And, by the way, also included would be any files or documents that exist
2159 within that domain since no path limitations are specified. (Correctly
2160 speaking: It matches any FQDN that contains <literal>example</literal> as
2161 a domain.) This might be <literal>www.example.com</literal>,
2162 <literal>news.example.de</literal>, or
2163 <literal>www.example.net/cgi/testing.pl</literal> for instance. All these
2171 Additionally, there are wild-cards that you can use in the domain names
2172 themselves. These work similarly to shell globbing type wild-cards:
2173 <quote>*</quote> represents zero or more arbitrary characters (this is
2175 <ulink url="http://en.wikipedia.org/wiki/Regular_expressions"><quote>Regular
2176 Expression</quote></ulink> based syntax of <quote>.*</quote>),
2177 <quote>?</quote> represents any single character (this is equivalent to the
2178 regular expression syntax of a simple <quote>.</quote>), and you can define
2179 <quote>character classes</quote> in square brackets which is similar to
2180 the same regular expression technique. All of this can be freely mixed:
2185 <term><literal>ad*.example.com</literal></term>
2188 matches <quote>adserver.example.com</quote>,
2189 <quote>ads.example.com</quote>, etc but not <quote>sfads.example.com</quote>
2194 <term><literal>*ad*.example.com</literal></term>
2197 matches all of the above, and then some.
2202 <term><literal>.?pix.com</literal></term>
2205 matches <literal>www.ipix.com</literal>,
2206 <literal>pictures.epix.com</literal>, <literal>a.b.c.d.e.upix.com</literal> etc.
2211 <term><literal>www[1-9a-ez].example.c*</literal></term>
2214 matches <literal>www1.example.com</literal>,
2215 <literal>www4.example.cc</literal>, <literal>wwwd.example.cy</literal>,
2216 <literal>wwwz.example.com</literal> etc., but <emphasis>not</emphasis>
2217 <literal>wwww.example.com</literal>.
2224 While flexible, this is not the sophistication of full regular expression based syntax.
2229 <!-- ~ End section ~ -->
2232 <!-- ~~~~~ New section ~~~~~ -->
2233 <sect3><title>The Path Pattern</title>
2236 <application>Privoxy</application> uses <quote>modern</quote> POSIX 1003.2
2237 <ulink url="http://en.wikipedia.org/wiki/Regular_expressions"><quote>Regular
2238 Expressions</quote></ulink> for matching the path portion (after the slash),
2239 and is thus more flexible.
2243 There is an <link linkend="regex">Appendix</link> with a brief quick-start into regular
2244 expressions, you also might want to have a look at your operating system's documentation
2245 on regular expressions (try <literal>man re_format</literal>).
2249 Note that the path pattern is automatically left-anchored at the <quote>/</quote>,
2250 i.e. it matches as if it would start with a <quote>^</quote> (regular expression speak
2251 for the beginning of a line).
2255 Please also note that matching in the path is <emphasis>CASE INSENSITIVE</emphasis>
2256 by default, but you can switch to case sensitive at any point in the pattern by using the
2257 <quote>(?-i)</quote> switch: <literal>www.example.com/(?-i)PaTtErN.*</literal> will match
2258 only documents whose path starts with <literal>PaTtErN</literal> in
2259 <emphasis>exactly</emphasis> this capitalization.
2264 <term><literal>.example.com/.*</literal></term>
2267 Is equivalent to just <quote>.example.com</quote>, since any documents
2268 within that domain are matched with or without the <quote>.*</quote>
2269 regular expression. This is redundant
2274 <term><literal>.example.com/.*/index.html$</literal></term>
2277 Will match any page in the domain of <quote>example.com</quote> that is
2278 named <quote>index.html</quote>, and that is part of some path. For
2279 example, it matches <quote>www.example.com/testing/index.html</quote> but
2280 NOT <quote>www.example.com/index.html</quote> because the regular
2281 expression called for at least two <quote>/'s</quote>, thus the path
2282 requirement. It also would match
2283 <quote>www.example.com/testing/index_html</quote>, because of the
2284 special meta-character <quote>.</quote>.
2289 <term><literal>.example.com/(.*/)?index\.html$</literal></term>
2292 This regular expression is conditional so it will match any page
2293 named <quote>index.html</quote> regardless of path which in this case can
2294 have one or more <quote>/'s</quote>. And this one must contain exactly
2295 <quote>.html</quote> (but does not have to end with that!).
2300 <term><literal>.example.com/(.*/)(ads|banners?|junk)</literal></term>
2303 This regular expression will match any path of <quote>example.com</quote>
2304 that contains any of the words <quote>ads</quote>, <quote>banner</quote>,
2305 <quote>banners</quote> (because of the <quote>?</quote>) or <quote>junk</quote>.
2306 The path does not have to end in these words, just contain them.
2311 <term><literal>.example.com/(.*/)(ads|banners?|junk)/.*\.(jpe?g|gif|png)$</literal></term>
2314 This is very much the same as above, except now it must end in either
2315 <quote>.jpg</quote>, <quote>.jpeg</quote>, <quote>.gif</quote> or <quote>.png</quote>. So this
2316 one is limited to common image formats.
2323 There are many, many good examples to be found in <filename>default.action</filename>,
2324 and more tutorials below in <link linkend="regex">Appendix on regular expressions</link>.
2329 <!-- ~ End section ~ -->
2332 <!-- ~~~~~ New section ~~~~~ -->
2333 <sect3 id="tag-pattern"><title>The Tag Pattern</title>
2336 Tag patterns are used to change the applying actions based on the
2337 request's tags. Tags can be created with either the
2338 <link linkend="CLIENT-HEADER-TAGGER">client-header-tagger</link>
2339 or the <link linkend="SERVER-HEADER-TAGGER">server-header-tagger</link> action.
2343 Tag patterns have to start with <quote>TAG:</quote>, so &my-app;
2344 can tell them apart from URL patterns. Everything after the colon
2345 including white space, is interpreted as a regular expression with
2346 path pattern syntax, except that tag patterns aren't left-anchored
2347 automatically (&my-app; doesn't silently add a <quote>^</quote>,
2348 you have to do it yourself if you need it).
2352 To match all requests that are tagged with <quote>foo</quote>
2353 your pattern line should be <quote>TAG:^foo$</quote>,
2354 <quote>TAG:foo</quote> would work as well, but it would also
2355 match requests whose tags contain <quote>foo</quote> somewhere.
2356 <quote>TAG: foo</quote> wouldn't work as it requires white space.
2360 Sections can contain URL and tag patterns at the same time,
2361 but tag patterns are checked after the URL patterns and thus
2362 always overrule them, even if they are located before the URL patterns.
2366 Once a new tag is added, Privoxy checks right away if it's matched by one
2367 of the tag patterns and updates the action settings accordingly. As a result
2368 tags can be used to activate other tagger actions, as long as these other
2369 taggers look for headers that haven't already be parsed.
2373 For example you could tag client requests which use the
2374 <literal>POST</literal> method,
2375 then use this tag to activate another tagger that adds a tag if cookies
2376 are sent, and then use a block action based on the cookie tag. This allows
2377 the outcome of one action, to be input into a subsequent action. However if
2378 you'd reverse the position of the described taggers, and activated the
2379 method tagger based on the cookie tagger, no method tags would be created.
2380 The method tagger would look for the request line, but at the time
2381 the cookie tag is created, the request line has already been parsed.
2385 While this is a limitation you should be aware of, this kind of
2386 indirection is seldom needed anyway and even the example doesn't
2387 make too much sense.
2392 <!-- ~~~~~ New section ~~~~~ -->
2393 <sect3 id="negative-tag-patterns"><title>The Negative Tag Patterns</title>
2396 To match requests that do not have a certain tag, specify a negative tag pattern
2397 by prefixing the tag pattern line with either <quote>NO-REQUEST-TAG:</quote>
2398 or <quote>NO-RESPONSE-TAG:</quote> instead of <quote>TAG:</quote>.
2402 Negative tag patterns created with <quote>NO-REQUEST-TAG:</quote> are checked
2403 after all client headers are scanned, the ones created with <quote>NO-RESPONSE-TAG:</quote>
2404 are checked after all server headers are scanned. In both cases all the created
2405 tags are considered.
2411 <!-- ~ End section ~ -->
2414 <!-- ~~~~~ New section ~~~~~ -->
2416 <sect2 id="actions">
2417 <title>Actions</title>
2419 All actions are disabled by default, until they are explicitly enabled
2420 somewhere in an actions file. Actions are turned on if preceded with a
2421 <quote>+</quote>, and turned off if preceded with a <quote>-</quote>. So a
2422 <literal>+action</literal> means <quote>do that action</quote>, e.g.
2423 <literal>+block</literal> means <quote>please block URLs that match the
2424 following patterns</quote>, and <literal>-block</literal> means <quote>don't
2425 block URLs that match the following patterns, even if <literal>+block</literal>
2426 previously applied.</quote>
2431 Again, actions are invoked by placing them on a line, enclosed in curly braces and
2432 separated by whitespace, like in
2433 <literal>{+some-action -some-other-action{some-parameter}}</literal>,
2434 followed by a list of URL patterns, one per line, to which they apply.
2435 Together, the actions line and the following pattern lines make up a section
2436 of the actions file.
2440 Actions fall into three categories:
2447 Boolean, i.e the action can only be <quote>enabled</quote> or
2448 <quote>disabled</quote>. Syntax:
2452 +<replaceable class="function">name</replaceable> # enable action <replaceable class="parameter">name</replaceable>
2453 -<replaceable class="function">name</replaceable> # disable action <replaceable class="parameter">name</replaceable></screen>
2456 Example: <literal>+handle-as-image</literal>
2463 Parameterized, where some value is required in order to enable this type of action.
2468 +<replaceable class="function">name</replaceable>{<replaceable class="parameter">param</replaceable>} # enable action and set parameter to <replaceable class="parameter">param</replaceable>,
2469 # overwriting parameter from previous match if necessary
2470 -<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:
2492 +<replaceable class="function">name</replaceable>{<replaceable class="parameter">param</replaceable>} # enable action and add <replaceable class="parameter">param</replaceable> to the list of parameters
2493 -<replaceable class="function">name</replaceable>{<replaceable class="parameter">param</replaceable>} # remove the parameter <replaceable class="parameter">param</replaceable> from the list of parameters
2494 # If it was the last one left, disable the action.
2495 <replaceable class="parameter">-name</replaceable> # disable this action completely and remove all parameters from the list</screen>
2498 Examples: <literal>+add-header{X-Fun-Header: Some text}</literal> and
2499 <literal>+filter{html-annoyances}</literal>
2507 If nothing is specified in any actions file, no <quote>actions</quote> are
2508 taken. So in this case <application>Privoxy</application> would just be a
2509 normal, non-blocking, non-filtering proxy. You must specifically enable the
2510 privacy and blocking features you need (although the provided default actions
2511 files will give a good starting point).
2515 Later defined action sections always over-ride earlier ones of the same type.
2516 So exceptions to any rules you make, should come in the latter part of the file (or
2517 in a file that is processed later when using multiple actions files such
2518 as <filename>user.action</filename>). For multi-valued actions, the actions
2519 are applied in the order they are specified. Actions files are processed in
2520 the order they are defined in <filename>config</filename> (the default
2521 installation has three actions files). It also quite possible for any given
2522 URL to match more than one <quote>pattern</quote> (because of wildcards and
2523 regular expressions), and thus to trigger more than one set of actions! Last
2527 <!-- start actions listing -->
2529 The list of valid <application>Privoxy</application> actions are:
2533 <!-- ********************************************************** -->
2534 <!-- Please note the below defined actions use id's that are -->
2535 <!-- probably linked from other places, so please don't change. -->
2537 <!-- ********************************************************** -->
2540 <!-- ~~~~~ New section ~~~~~ -->
2542 <sect3 renderas="sect4" id="add-header">
2543 <title>add-header</title>
2547 <term>Typical use:</term>
2549 <para>Confuse log analysis, custom applications</para>
2554 <term>Effect:</term>
2557 Sends a user defined HTTP header to the web server.
2564 <!-- boolean, parameterized, Multi-value -->
2566 <para>Multi-value.</para>
2571 <term>Parameter:</term>
2574 Any string value is possible. Validity of the defined HTTP headers is not checked.
2575 It is recommended that you use the <quote><literal>X-</literal></quote> prefix
2585 This action may be specified multiple times, in order to define multiple
2586 headers. This is rarely needed for the typical user. If you don't know what
2587 <quote>HTTP headers</quote> are, you definitely don't need to worry about this
2591 Headers added by this action are not modified by other actions.
2597 <term>Example usage:</term>
2600 <screen>+add-header{X-User-Tracking: sucks}</screen>
2608 <!-- ~~~~~ New section ~~~~~ -->
2609 <sect3 renderas="sect4" id="block">
2610 <title>block</title>
2614 <term>Typical use:</term>
2616 <para>Block ads or other unwanted content</para>
2621 <term>Effect:</term>
2624 Requests for URLs to which this action applies are blocked, i.e. the
2625 requests are trapped by &my-app; and the requested URL is never retrieved,
2626 but is answered locally with a substitute page or image, as determined by
2628 linkend="handle-as-image">handle-as-image</link></literal>,
2630 linkend="set-image-blocker">set-image-blocker</link></literal>, and
2632 linkend="handle-as-empty-document">handle-as-empty-document</link></literal> actions.
2640 <!-- boolean, parameterized, Multi-value -->
2642 <para>Parameterized.</para>
2647 <term>Parameter:</term>
2649 <para>A block reason that should be given to the user.</para>
2657 <application>Privoxy</application> sends a special <quote>BLOCKED</quote> page
2658 for requests to blocked pages. This page contains the block reason given as
2659 parameter, a link to find out why the block action applies, and a click-through
2660 to the blocked content (the latter only if the force feature is available and
2664 A very important exception occurs if <emphasis>both</emphasis>
2665 <literal>block</literal> and <literal><link linkend="handle-as-image">handle-as-image</link></literal>,
2666 apply to the same request: it will then be replaced by an image. If
2667 <literal><link linkend="set-image-blocker">set-image-blocker</link></literal>
2668 (see below) also applies, the type of image will be determined by its parameter,
2669 if not, the standard checkerboard pattern is sent.
2672 It is important to understand this process, in order
2673 to understand how <application>Privoxy</application> deals with
2674 ads and other unwanted content. Blocking is a core feature, and one
2675 upon which various other features depend.
2678 The <literal><link linkend="filter">filter</link></literal>
2679 action can perform a very similar task, by <quote>blocking</quote>
2680 banner images and other content through rewriting the relevant URLs in the
2681 document's HTML source, so they don't get requested in the first place.
2682 Note that this is a totally different technique, and it's easy to confuse the two.
2688 <term>Example usage (section):</term>
2691 <screen>{+block{No nasty stuff for you.}}
2692 # Block and replace with "blocked" page
2693 .nasty-stuff.example.com
2695 {+block{Doubleclick banners.} +handle-as-image}
2696 # Block and replace with image
2700 {+block{Layered ads.} +handle-as-empty-document}
2701 # Block and then ignore
2702 adserver.example.net/.*\.js$</screen>
2712 <!-- ~~~~~ New section ~~~~~ -->
2713 <sect3 renderas="sect4" id="change-x-forwarded-for">
2714 <title>change-x-forwarded-for</title>
2718 <term>Typical use:</term>
2720 <para>Improve privacy by not forwarding the source of the request in the HTTP headers.</para>
2725 <term>Effect:</term>
2728 Deletes the <quote>X-Forwarded-For:</quote> HTTP header from the client request,
2736 <!-- Boolean, Parameterized, Multi-value -->
2738 <para>Parameterized.</para>
2743 <term>Parameter:</term>
2747 <para><quote>block</quote> to delete the header.</para>
2751 <quote>add</quote> to create the header (or append
2752 the client's IP address to an already existing one).
2763 It is safe and recommended to use <literal>block</literal>.
2766 Forwarding the source address of the request may make
2767 sense in some multi-user setups but is also a privacy risk.
2772 <term>Example usage:</term>
2775 <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>
2856 # Hide Tor exit notation in Host and Referer Headers
2857 {+client-header-filter{hide-tor-exit-notation}}
2868 <!-- ~~~~~ New section ~~~~~ -->
2869 <sect3 renderas="sect4" id="client-header-tagger">
2870 <title>client-header-tagger</title>
2874 <term>Typical use:</term>
2877 Block requests based on their headers.
2883 <term>Effect:</term>
2886 Client headers to which this action applies are filtered on-the-fly through
2887 the specified regular expression based substitutions, the result is used as
2895 <!-- boolean, parameterized, Multi-value -->
2897 <para>Multi-value.</para>
2902 <term>Parameter:</term>
2905 The name of a client-header tagger, as defined in one of the
2906 <link linkend="filter-file">filter files</link>.
2915 Client-header taggers are applied to each header on its own,
2916 and as the header isn't modified, each tagger <quote>sees</quote>
2920 Client-header taggers are the first actions that are executed
2921 and their tags can be used to control every other action.
2927 <term>Example usage (section):</term>
2931 # Tag every request with the User-Agent header
2932 {+client-header-tagger{user-agent}}
2935 # Tagging itself doesn't change the action
2936 # settings, sections with TAG patterns do:
2938 # If it's a download agent, use a different forwarding proxy,
2939 # show the real User-Agent and make sure resume works.
2940 {+forward-override{forward-socks5 10.0.0.2:2222 .} \
2941 -hide-if-modified-since \
2942 -overwrite-last-modified \
2947 TAG:^User-Agent: NetBSD-ftp/
2948 TAG:^User-Agent: Novell ZYPP Installer
2949 TAG:^User-Agent: RPM APT-HTTP/
2950 TAG:^User-Agent: fetch libfetch/
2951 TAG:^User-Agent: Ubuntu APT-HTTP/
2952 TAG:^User-Agent: MPlayer/
2957 # Tag all requests with the Range header set
2958 {+client-header-tagger{range-requests}}
2961 # Disable filtering for the tagged requests.
2963 # With filtering enabled Privoxy would remove the Range headers
2964 # to be able to filter the whole response. The downside is that
2965 # it prevents clients from resuming downloads or skipping over
2966 # parts of multimedia files.
2967 {-filter -deanimate-gifs}
2978 <!-- ~~~~~ New section ~~~~~ -->
2979 <sect3 renderas="sect4" id="content-type-overwrite">
2980 <title>content-type-overwrite</title>
2984 <term>Typical use:</term>
2986 <para>Stop useless download menus from popping up, or change the browser's rendering mode</para>
2991 <term>Effect:</term>
2994 Replaces the <quote>Content-Type:</quote> HTTP server header.
3001 <!-- Boolean, Parameterized, Multi-value -->
3003 <para>Parameterized.</para>
3008 <term>Parameter:</term>
3020 The <quote>Content-Type:</quote> HTTP server header is used by the
3021 browser to decide what to do with the document. The value of this
3022 header can cause the browser to open a download menu instead of
3023 displaying the document by itself, even if the document's format is
3024 supported by the browser.
3027 The declared content type can also affect which rendering mode
3028 the browser chooses. If XHTML is delivered as <quote>text/html</quote>,
3029 many browsers treat it as yet another broken HTML document.
3030 If it is send as <quote>application/xml</quote>, browsers with
3031 XHTML support will only display it, if the syntax is correct.
3034 If you see a web site that proudly uses XHTML buttons, but sets
3035 <quote>Content-Type: text/html</quote>, you can use &my-app;
3036 to overwrite it with <quote>application/xml</quote> and validate
3037 the web master's claim inside your XHTML-supporting browser.
3038 If the syntax is incorrect, the browser will complain loudly.
3041 You can also go the opposite direction: if your browser prints
3042 error messages instead of rendering a document falsely declared
3043 as XHTML, you can overwrite the content type with
3044 <quote>text/html</quote> and have it rendered as broken HTML document.
3047 By default <literal>content-type-overwrite</literal> only replaces
3048 <quote>Content-Type:</quote> headers that look like some kind of text.
3049 If you want to overwrite it unconditionally, you have to combine it with
3050 <literal><link linkend="force-text-mode">force-text-mode</link></literal>.
3051 This limitation exists for a reason, think twice before circumventing it.
3054 Most of the time it's easier to replace this action with a custom
3055 <literal><link linkend="server-header-filter">server-header filter</link></literal>.
3056 It allows you to activate it for every document of a certain site and it will still
3057 only replace the content types you aimed at.
3060 Of course you can apply <literal>content-type-overwrite</literal>
3061 to a whole site and then make URL based exceptions, but it's a lot
3062 more work to get the same precision.
3068 <term>Example usage (sections):</term>
3071 <screen># Check if www.example.net/ really uses valid XHTML
3072 { +content-type-overwrite{application/xml} }
3075 # but leave the content type unmodified if the URL looks like a style sheet
3076 {-content-type-overwrite}
3077 www.example.net/.*\.css$
3078 www.example.net/.*style
3087 <!-- ~~~~~ New section ~~~~~ -->
3088 <sect3 renderas="sect4" id="crunch-client-header">
3092 <title>crunch-client-header</title>
3096 <term>Typical use:</term>
3098 <para>Remove a client header <application>Privoxy</application> has no dedicated action for.</para>
3103 <term>Effect:</term>
3106 Deletes every header sent by the client that contains the string the user supplied as parameter.
3113 <!-- Boolean, Parameterized, Multi-value -->
3115 <para>Parameterized.</para>
3120 <term>Parameter:</term>
3132 This action allows you to block client headers for which no dedicated
3133 <application>Privoxy</application> action exists.
3134 <application>Privoxy</application> will remove every client header that
3135 contains the string you supplied as parameter.
3138 Regular expressions are <emphasis>not supported</emphasis> and you can't
3139 use this action to block different headers in the same request, unless
3140 they contain the same string.
3143 <literal>crunch-client-header</literal> is only meant for quick tests.
3144 If you have to block several different headers, or only want to modify
3145 parts of them, you should use a
3146 <literal><link linkend="client-header-filter">client-header filter</link></literal>.
3150 Don't block any header without understanding the consequences.
3157 <term>Example usage (section):</term>
3160 <screen># Block the non-existent "Privacy-Violation:" client header
3161 { +crunch-client-header{Privacy-Violation:} }
3171 <!-- ~~~~~ New section ~~~~~ -->
3172 <sect3 renderas="sect4" id="crunch-if-none-match">
3173 <title>crunch-if-none-match</title>
3179 <term>Typical use:</term>
3181 <para>Prevent yet another way to track the user's steps between sessions.</para>
3186 <term>Effect:</term>
3189 Deletes the <quote>If-None-Match:</quote> HTTP client header.
3196 <!-- Boolean, Parameterized, Multi-value -->
3198 <para>Boolean.</para>
3203 <term>Parameter:</term>
3215 Removing the <quote>If-None-Match:</quote> HTTP client header
3216 is useful for filter testing, where you want to force a real
3217 reload instead of getting status code <quote>304</quote> which
3218 would cause the browser to use a cached copy of the page.
3221 It is also useful to make sure the header isn't used as a cookie
3222 replacement (unlikely but possible).
3225 Blocking the <quote>If-None-Match:</quote> header shouldn't cause any
3226 caching problems, as long as the <quote>If-Modified-Since:</quote> header
3227 isn't blocked or missing as well.
3230 It is recommended to use this action together with
3231 <literal><link linkend="hide-if-modified-since">hide-if-modified-since</link></literal>
3233 <literal><link linkend="overwrite-last-modified">overwrite-last-modified</link></literal>.
3239 <term>Example usage (section):</term>
3242 <screen># Let the browser revalidate cached documents but don't
3243 # allow the server to use the revalidation headers for user tracking.
3244 {+hide-if-modified-since{-60} \
3245 +overwrite-last-modified{randomize} \
3246 +crunch-if-none-match}
3255 <!-- ~~~~~ New section ~~~~~ -->
3256 <sect3 renderas="sect4" id="crunch-incoming-cookies">
3257 <title>crunch-incoming-cookies</title>
3261 <term>Typical use:</term>
3264 Prevent the web server from setting HTTP cookies on your system
3270 <term>Effect:</term>
3273 Deletes any <quote>Set-Cookie:</quote> HTTP headers from server replies.
3280 <!-- Boolean, Parameterized, Multi-value -->
3282 <para>Boolean.</para>
3287 <term>Parameter:</term>
3299 This action is only concerned with <emphasis>incoming</emphasis> HTTP cookies. For
3300 <emphasis>outgoing</emphasis> HTTP cookies, use
3301 <literal><link linkend="crunch-outgoing-cookies">crunch-outgoing-cookies</link></literal>.
3302 Use <emphasis>both</emphasis> to disable HTTP cookies completely.
3305 It makes <emphasis>no sense at all</emphasis> to use this action in conjunction
3306 with the <literal><link linkend="session-cookies-only">session-cookies-only</link></literal> action,
3307 since it would prevent the session cookies from being set. See also
3308 <literal><link linkend="filter-content-cookies">filter-content-cookies</link></literal>.
3314 <term>Example usage:</term>
3317 <screen>+crunch-incoming-cookies</screen>
3325 <!-- ~~~~~ New section ~~~~~ -->
3326 <sect3 renderas="sect4" id="crunch-server-header">
3327 <title>crunch-server-header</title>
3333 <term>Typical use:</term>
3335 <para>Remove a server header <application>Privoxy</application> has no dedicated action for.</para>
3340 <term>Effect:</term>
3343 Deletes every header sent by the server that contains the string the user supplied as parameter.
3350 <!-- Boolean, Parameterized, Multi-value -->
3352 <para>Parameterized.</para>
3357 <term>Parameter:</term>
3369 This action allows you to block server headers for which no dedicated
3370 <application>Privoxy</application> action exists. <application>Privoxy</application>
3371 will remove every server header that contains the string you supplied as parameter.
3374 Regular expressions are <emphasis>not supported</emphasis> and you can't
3375 use this action to block different headers in the same request, unless
3376 they contain the same string.
3379 <literal>crunch-server-header</literal> is only meant for quick tests.
3380 If you have to block several different headers, or only want to modify
3381 parts of them, you should use a custom
3382 <literal><link linkend="server-header-filter">server-header filter</link></literal>.
3386 Don't block any header without understanding the consequences.
3393 <term>Example usage (section):</term>
3396 <screen># Crunch server headers that try to prevent caching
3397 { +crunch-server-header{no-cache} }
3406 <!-- ~~~~~ New section ~~~~~ -->
3407 <sect3 renderas="sect4" id="crunch-outgoing-cookies">
3408 <title>crunch-outgoing-cookies</title>
3412 <term>Typical use:</term>
3415 Prevent the web server from reading any HTTP cookies from your system
3421 <term>Effect:</term>
3424 Deletes any <quote>Cookie:</quote> HTTP headers from client requests.
3431 <!-- Boolean, Parameterized, Multi-value -->
3433 <para>Boolean.</para>
3438 <term>Parameter:</term>
3450 This action is only concerned with <emphasis>outgoing</emphasis> HTTP cookies. For
3451 <emphasis>incoming</emphasis> HTTP cookies, use
3452 <literal><link linkend="crunch-incoming-cookies">crunch-incoming-cookies</link></literal>.
3453 Use <emphasis>both</emphasis> to disable HTTP cookies completely.
3456 It makes <emphasis>no sense at all</emphasis> to use this action in conjunction
3457 with the <literal><link linkend="session-cookies-only">session-cookies-only</link></literal> action,
3458 since it would prevent the session cookies from being read.
3464 <term>Example usage:</term>
3467 <screen>+crunch-outgoing-cookies</screen>
3476 <!-- ~~~~~ New section ~~~~~ -->
3477 <sect3 renderas="sect4" id="deanimate-gifs">
3478 <title>deanimate-gifs</title>
3482 <term>Typical use:</term>
3484 <para>Stop those annoying, distracting animated GIF images.</para>
3489 <term>Effect:</term>
3492 De-animate GIF animations, i.e. reduce them to their first or last image.
3499 <!-- boolean, parameterized, Multi-value -->
3501 <para>Parameterized.</para>
3506 <term>Parameter:</term>
3509 <quote>last</quote> or <quote>first</quote>
3518 This will also shrink the images considerably (in bytes, not pixels!). If
3519 the option <quote>first</quote> is given, the first frame of the animation
3520 is used as the replacement. If <quote>last</quote> is given, the last
3521 frame of the animation is used instead, which probably makes more sense for
3522 most banner animations, but also has the risk of not showing the entire
3523 last frame (if it is only a delta to an earlier frame).
3526 You can safely use this action with patterns that will also match non-GIF
3527 objects, because no attempt will be made at anything that doesn't look like
3534 <term>Example usage:</term>
3537 <screen>+deanimate-gifs{last}</screen>
3544 <!-- ~~~~~ New section ~~~~~ -->
3545 <sect3 renderas="sect4" id="downgrade-http-version">
3546 <title>downgrade-http-version</title>
3550 <term>Typical use:</term>
3552 <para>Work around (very rare) problems with HTTP/1.1</para>
3557 <term>Effect:</term>
3560 Downgrades HTTP/1.1 client requests and server replies to HTTP/1.0.
3567 <!-- boolean, parameterized, Multi-value -->
3569 <para>Boolean.</para>
3574 <term>Parameter:</term>
3586 This is a left-over from the time when <application>Privoxy</application>
3587 didn't support important HTTP/1.1 features well. It is left here for the
3588 unlikely case that you experience HTTP/1.1-related problems with some server
3592 Note that enabling this action is only a workaround. It should not
3593 be enabled for sites that work without it. While it shouldn't break
3594 any pages, it has an (usually negative) performance impact.
3597 If you come across a site where enabling this action helps, please report it,
3598 so the cause of the problem can be analyzed. If the problem turns out to be
3599 caused by a bug in <application>Privoxy</application> it should be
3600 fixed so the following release works without the work around.
3606 <term>Example usage (section):</term>
3609 <screen>{+downgrade-http-version}
3610 problem-host.example.com</screen>
3618 <!-- ~~~~~ New section ~~~~~ -->
3619 <sect3 renderas="sect4" id="external-filter">
3620 <title>external-filter</title>
3624 <term>Typical use:</term>
3626 <para>Modify content using a programming language of your choice.</para>
3631 <term>Effect:</term>
3634 All instances of text-based type, most notably HTML and JavaScript, to which
3635 this action applies, can be filtered on-the-fly through the specified external
3637 By default plain text documents are exempted from filtering, because web
3638 servers often use the <literal>text/plain</literal> MIME type for all files
3639 whose type they don't know.)
3646 <!-- boolean, parameterized, Multi-value -->
3648 <para>Multi-value.</para>
3653 <term>Parameter:</term>
3656 The name of an external content filter, as defined in the
3657 <link linkend="filter-file">filter file</link>.
3658 External filters can be defined in one or more files as defined by the
3659 <literal><link linkend="filterfile">filterfile</link></literal>
3660 option in the <link linkend="config">config file</link>.
3663 When used in its negative form,
3664 and without parameters, <emphasis>all</emphasis> filtering with external
3665 filters is completely disabled.
3674 External filters are scripts or programs that can modify the content in
3675 case common <literal><link linkend="filter">filters</link></literal>
3676 aren't powerful enough. With the exception that this action doesn't
3677 use pcrs-based filters, the notes in the
3678 <literal><link linkend="filter">filter</link></literal> section apply.
3682 Currently external filters are executed with &my-app;'s privileges.
3683 Only use external filters you understand and trust.
3687 This feature is experimental, the <literal><link
3688 linkend="external-filter-syntax">syntax</link></literal>
3689 may change in the future.
3696 <term>Example usage:</term>
3699 <screen>+external-filter{fancy-filter}</screen>
3706 <!-- ~~~~~ New section ~~~~~ -->
3707 <sect3 renderas="sect4" id="fast-redirects">
3708 <title>fast-redirects</title>
3712 <term>Typical use:</term>
3714 <para>Fool some click-tracking scripts and speed up indirect links.</para>
3719 <term>Effect:</term>
3722 Detects redirection URLs and redirects the browser without contacting
3723 the redirection server first.
3730 <!-- boolean, parameterized, Multi-value -->
3732 <para>Parameterized.</para>
3737 <term>Parameter:</term>
3742 <quote>simple-check</quote> to just search for the string <quote>http://</quote>
3743 to detect redirection URLs.
3748 <quote>check-decoded-url</quote> to decode URLs (if necessary) before searching
3749 for redirection URLs.
3760 Many sites, like yahoo.com, don't just link to other sites. Instead, they
3761 will link to some script on their own servers, giving the destination as a
3762 parameter, which will then redirect you to the final target. URLs
3763 resulting from this scheme typically look like:
3764 <quote>http://www.example.org/click-tracker.cgi?target=http%3a//www.example.net/</quote>.
3767 Sometimes, there are even multiple consecutive redirects encoded in the
3768 URL. These redirections via scripts make your web browsing more traceable,
3769 since the server from which you follow such a link can see where you go
3770 to. Apart from that, valuable bandwidth and time is wasted, while your
3771 browser asks the server for one redirect after the other. Plus, it feeds
3775 This feature is currently not very smart and is scheduled for improvement.
3776 If it is enabled by default, you will have to create some exceptions to
3777 this action. It can lead to failures in several ways:
3780 Not every URLs with other URLs as parameters is evil.
3781 Some sites offer a real service that requires this information to work.
3782 For example a validation service needs to know, which document to validate.
3783 <literal>fast-redirects</literal> assumes that every URL parameter that
3784 looks like another URL is a redirection target, and will always redirect to
3785 the last one. Most of the time the assumption is correct, but if it isn't,
3786 the user gets redirected anyway.
3789 Another failure occurs if the URL contains other parameters after the URL parameter.
3791 <quote>http://www.example.org/?redirect=http%3a//www.example.net/&foo=bar</quote>.
3792 contains the redirection URL <quote>http://www.example.net/</quote>,
3793 followed by another parameter. <literal>fast-redirects</literal> doesn't know that
3794 and will cause a redirect to <quote>http://www.example.net/&foo=bar</quote>.
3795 Depending on the target server configuration, the parameter will be silently ignored
3796 or lead to a <quote>page not found</quote> error. You can prevent this problem by
3797 first using the <literal><link linkend="redirect">redirect</link></literal> action
3798 to remove the last part of the URL, but it requires a little effort.
3801 To detect a redirection URL, <literal>fast-redirects</literal> only
3802 looks for the string <quote>http://</quote>, either in plain text
3803 (invalid but often used) or encoded as <quote>http%3a//</quote>.
3804 Some sites use their own URL encoding scheme, encrypt the address
3805 of the target server or replace it with a database id. In theses cases
3806 <literal>fast-redirects</literal> is fooled and the request reaches the
3807 redirection server where it probably gets logged.
3813 <term>Example usage:</term>
3817 { +fast-redirects{simple-check} }
3820 { +fast-redirects{check-decoded-url} }
3821 another.example.com/testing</screen>
3830 <!-- ~~~~~ New section ~~~~~ -->
3831 <sect3 renderas="sect4" id="filter">
3832 <title>filter</title>
3836 <term>Typical use:</term>
3838 <para>Get rid of HTML and JavaScript annoyances, banner advertisements (by size),
3839 do fun text replacements, add personalized effects, etc.</para>
3844 <term>Effect:</term>
3847 All instances of text-based type, most notably HTML and JavaScript, to which
3848 this action applies, can be filtered on-the-fly through the specified regular
3849 expression based substitutions. (Note: as of version 3.0.3 plain text documents
3850 are exempted from filtering, because web servers often use the
3851 <literal>text/plain</literal> MIME type for all files whose type they don't know.)
3858 <!-- boolean, parameterized, Multi-value -->
3860 <para>Multi-value.</para>
3865 <term>Parameter:</term>
3868 The name of a content filter, as defined in the <link linkend="filter-file">filter file</link>.
3869 Filters can be defined in one or more files as defined by the
3870 <literal><link linkend="filterfile">filterfile</link></literal>
3871 option in the <link linkend="config">config file</link>.
3872 <filename>default.filter</filename> is the collection of filters
3873 supplied by the developers. Locally defined filters should go
3874 in their own file, such as <filename>user.filter</filename>.
3877 When used in its negative form,
3878 and without parameters, <emphasis>all</emphasis> filtering is completely disabled.
3887 For your convenience, there are a number of pre-defined filters available
3888 in the distribution filter file that you can use. See the examples below for
3892 Filtering requires buffering the page content, which may appear to
3893 slow down page rendering since nothing is displayed until all content has
3894 passed the filters. (The total time until the page is completely rendered
3895 doesn't change much, but it may be perceived as slower since the page is
3896 not incrementally displayed.)
3897 This effect will be more noticeable on slower connections.
3900 <quote>Rolling your own</quote>
3901 filters requires a knowledge of
3902 <ulink url="http://en.wikipedia.org/wiki/Regular_expressions"><quote>Regular
3903 Expressions</quote></ulink> and
3904 <ulink url="http://en.wikipedia.org/wiki/Html"><quote>HTML</quote></ulink>.
3905 This is very powerful feature, and potentially very intrusive.
3906 Filters should be used with caution, and where an equivalent
3907 <quote>action</quote> is not available.
3910 The amount of data that can be filtered is limited to the
3911 <literal><link linkend="buffer-limit">buffer-limit</link></literal>
3912 option in the main <link linkend="config">config file</link>. The
3913 default is 4096 KB (4 Megs). Once this limit is exceeded, the buffered
3914 data, and all pending data, is passed through unfiltered.
3917 Inappropriate MIME types, such as zipped files, are not filtered at all.
3918 (Again, only text-based types except plain text). Encrypted SSL data
3919 (from HTTPS servers) cannot be filtered either, since this would violate
3920 the integrity of the secure transaction. In some situations it might
3921 be necessary to protect certain text, like source code, from filtering
3922 by defining appropriate <literal>-filter</literal> exceptions.
3925 Compressed content can't be filtered either, but if &my-app;
3926 is compiled with zlib support and a supported compression algorithm
3927 is used (gzip or deflate), &my-app; can first decompress the content
3931 If you use a &my-app; version without zlib support, but want filtering to work on
3932 as much documents as possible, even those that would normally be sent compressed,
3933 you must use the <literal><link linkend="prevent-compression">prevent-compression</link></literal>
3934 action in conjunction with <literal>filter</literal>.
3937 Content filtering can achieve some of the same effects as the
3938 <literal><link linkend="block">block</link></literal>
3939 action, i.e. it can be used to block ads and banners. But the mechanism
3940 works quite differently. One effective use, is to block ad banners
3941 based on their size (see below), since many of these seem to be somewhat
3945 <link linkend="contact">Feedback</link> with suggestions for new or
3946 improved filters is particularly welcome!
3949 The below list has only the names and a one-line description of each
3950 predefined filter. There are <link linkend="predefined-filters">more
3951 verbose explanations</link> of what these filters do in the <link
3952 linkend="filter-file">filter file chapter</link>.
3958 <term>Example usage (with filters from the distribution <filename>default.filter</filename> file).
3959 See <link linkend="PREDEFINED-FILTERS">the Predefined Filters section</link> for
3960 more explanation on each:</term>
3963 <anchor id="filter-js-annoyances">
3964 <screen>+filter{js-annoyances} # Get rid of particularly annoying JavaScript abuse.</screen>
3967 <anchor id="filter-js-events">
3968 <screen>+filter{js-events} # Kill JavaScript event bindings and timers (Radically destructive! Only for extra nasty sites).</screen>
3971 <anchor id="filter-html-annoyances">
3972 <screen>+filter{html-annoyances} # Get rid of particularly annoying HTML abuse.</screen>
3975 <anchor id="filter-content-cookies">
3976 <screen>+filter{content-cookies} # Kill cookies that come in the HTML or JS content.</screen>
3979 <anchor id="filter-refresh-tags">
3980 <screen>+filter{refresh-tags} # Kill automatic refresh tags if refresh time is larger than 9 seconds.</screen>
3983 <anchor id="filter-unsolicited-popups">
3984 <screen>+filter{unsolicited-popups} # Disable only unsolicited pop-up windows.</screen>
3987 <anchor id="filter-all-popups">
3988 <screen>+filter{all-popups} # Kill all popups in JavaScript and HTML.</screen>
3991 <anchor id="filter-img-reorder">
3992 <screen>+filter{img-reorder} # Reorder attributes in <img> tags to make the banners-by-* filters more effective.</screen>
3995 <anchor id="filter-banners-by-size">
3996 <screen>+filter{banners-by-size} # Kill banners by size.</screen>
3999 <anchor id="filter-banners-by-link">
4000 <screen>+filter{banners-by-link} # Kill banners by their links to known clicktrackers.</screen>
4003 <anchor id="filter-webbugs">
4004 <screen>+filter{webbugs} # Squish WebBugs (1x1 invisible GIFs used for user tracking).</screen>
4007 <anchor id="filter-tiny-textforms">
4008 <screen>+filter{tiny-textforms} # Extend those tiny textareas up to 40x80 and kill the hard wrap.</screen>
4011 <anchor id="filter-jumping-windows">
4012 <screen>+filter{jumping-windows} # Prevent windows from resizing and moving themselves.</screen>
4015 <anchor id="filter-frameset-borders">
4016 <screen>+filter{frameset-borders} # Give frames a border and make them resizable.</screen>
4019 <anchor id="filter-iframes">
4020 <screen>+filter{iframes} # Removes all detected iframes. Should only be enabled for individual sites.</screen>
4023 <anchor id="filter-demoronizer">
4024 <screen>+filter{demoronizer} # Fix MS's non-standard use of standard charsets.</screen>
4027 <anchor id="filter-shockwave-flash">
4028 <screen>+filter{shockwave-flash} # Kill embedded Shockwave Flash objects.</screen>
4031 <anchor id="filter-quicktime-kioskmode">
4032 <screen>+filter{quicktime-kioskmode} # Make Quicktime movies saveable.</screen>
4035 <anchor id="filter-fun">
4036 <screen>+filter{fun} # Text replacements for subversive browsing fun!</screen>
4039 <anchor id="filter-crude-parental">
4040 <screen>+filter{crude-parental} # Crude parental filtering. Note that this filter doesn't work reliably.</screen>
4043 <anchor id="filter-ie-exploits">
4044 <screen>+filter{ie-exploits} # Disable some known Internet Explorer bug exploits.</screen>
4047 <anchor id="filter-site-specifics">
4048 <screen>+filter{site-specifics} # Cure for site-specific problems. Don't apply generally!</screen>
4051 <anchor id="filter-no-ping">
4052 <screen>+filter{no-ping} # Removes non-standard ping attributes in <a> and <area> tags.</screen>
4055 <anchor id="filter-google">
4056 <screen>+filter{google} # CSS-based block for Google text ads. Also removes a width limitation and the toolbar advertisement.</screen>
4059 <anchor id="filter-yahoo">
4060 <screen>+filter{yahoo} # CSS-based block for Yahoo text ads. Also removes a width limitation.</screen>
4063 <anchor id="filter-msn">
4064 <screen>+filter{msn} # CSS-based block for MSN text ads. Also removes tracking URLs and a width limitation.</screen>
4067 <anchor id="filter-blogspot">
4068 <screen>+filter{blogspot} # Cleans up some Blogspot blogs. Read the fine print before using this.</screen>
4076 <!-- ~~~~~ New section ~~~~~ -->
4077 <sect3 renderas="sect4" id="force-text-mode">
4078 <title>force-text-mode</title>
4084 <term>Typical use:</term>
4086 <para>Force <application>Privoxy</application> to treat a document as if it was in some kind of <emphasis>text</emphasis> format. </para>
4091 <term>Effect:</term>
4094 Declares a document as text, even if the <quote>Content-Type:</quote> isn't detected as such.
4101 <!-- Boolean, Parameterized, Multi-value -->
4103 <para>Boolean.</para>
4108 <term>Parameter:</term>
4120 As explained <literal><link linkend="filter">above</link></literal>,
4121 <application>Privoxy</application> tries to only filter files that are
4122 in some kind of text format. The same restrictions apply to
4123 <literal><link linkend="content-type-overwrite">content-type-overwrite</link></literal>.
4124 <literal>force-text-mode</literal> declares a document as text,
4125 without looking at the <quote>Content-Type:</quote> first.
4129 Think twice before activating this action. Filtering binary data
4130 with regular expressions can cause file damage.
4137 <term>Example usage:</term>
4150 <!-- ~~~~~ New section ~~~~~ -->
4151 <sect3 renderas="sect4" id="forward-override">
4152 <title>forward-override</title>
4158 <term>Typical use:</term>
4160 <para>Change the forwarding settings based on User-Agent or request origin</para>
4165 <term>Effect:</term>
4168 Overrules the forward directives in the configuration file.
4175 <!-- Boolean, Parameterized, Multi-value -->
4177 <para>Parameterized.</para>
4182 <term>Parameter:</term>
4186 <para><quote>forward .</quote> to use a direct connection without any additional proxies.</para>
4190 <quote>forward 127.0.0.1:8123</quote> to use the HTTP proxy listening at 127.0.0.1 port 8123.
4195 <quote>forward-socks4a 127.0.0.1:9050 .</quote> to use the socks4a proxy listening at
4196 127.0.0.1 port 9050. Replace <quote>forward-socks4a</quote> with <quote>forward-socks4</quote>
4197 to use a socks4 connection (with local DNS resolution) instead, use <quote>forward-socks5</quote>
4198 for socks5 connections (with remote DNS resolution).
4203 <quote>forward-socks4a 127.0.0.1:9050 proxy.example.org:8000</quote> to use the socks4a proxy
4204 listening at 127.0.0.1 port 9050 to reach the HTTP proxy listening at proxy.example.org port 8000.
4205 Replace <quote>forward-socks4a</quote> with <quote>forward-socks4</quote> to use a socks4 connection
4206 (with local DNS resolution) instead, use <quote>forward-socks5</quote>
4207 for socks5 connections (with remote DNS resolution).
4212 <quote>forward-webserver 127.0.0.1:80</quote> to use the HTTP
4213 server listening at 127.0.0.1 port 80 without adjusting the
4217 This makes it more convenient to use Privoxy to make
4218 existing websites available as onion services as well.
4221 Many websites serve content with hardcoded URLs and
4222 can't be easily adjusted to change the domain based
4223 on the one used by the client.
4226 Putting Privoxy between Tor and the webserver (or an stunnel
4227 that forwards to the webserver) allows to rewrite headers and
4228 content to make client and server happy at the same time.
4231 Using Privoxy for webservers that are only reachable through
4232 onion addresses and whose location is supposed to be secret
4233 is not recommended and should not be necessary anyway.
4244 This action takes parameters similar to the
4245 <link linkend="forwarding">forward</link> directives in the configuration
4246 file, but without the URL pattern. It can be used as replacement, but normally it's only
4247 used in cases where matching based on the request URL isn't sufficient.
4251 Please read the description for the <link linkend="forwarding">forward</link> directives before
4252 using this action. Forwarding to the wrong people will reduce your privacy and increase the
4253 chances of man-in-the-middle attacks.
4256 If the ports are missing or invalid, default values will be used. This might change
4257 in the future and you shouldn't rely on it. Otherwise incorrect syntax causes Privoxy
4258 to exit. Due to design limitations, invalid parameter syntax isn't detected until the
4259 action is used the first time.
4262 Use the <ulink url="http://config.privoxy.org/show-url-info">show-url-info CGI page</ulink>
4263 to verify that your forward settings do what you thought the do.
4270 <term>Example usage:</term>
4274 # Use an ssh tunnel for requests previously tagged as
4275 # <quote>User-Agent: fetch libfetch/2.0</quote> and make sure
4276 # resuming downloads continues to work.
4278 # This way you can continue to use Tor for your normal browsing,
4279 # without overloading the Tor network with your FreeBSD ports updates
4280 # or downloads of bigger files like ISOs.
4282 # Note that HTTP headers are easy to fake and therefore their
4283 # values are as (un)trustworthy as your clients and users.
4284 {+forward-override{forward-socks5 10.0.0.2:2222 .} \
4285 -hide-if-modified-since \
4286 -overwrite-last-modified \
4288 TAG:^User-Agent: fetch libfetch/2\.0$
4297 <!-- ~~~~~ New section ~~~~~ -->
4298 <sect3 renderas="sect4" id="handle-as-empty-document">
4299 <title>handle-as-empty-document</title>
4305 <term>Typical use:</term>
4307 <para>Mark URLs that should be replaced by empty documents <emphasis>if they get blocked</emphasis></para>
4312 <term>Effect:</term>
4315 This action alone doesn't do anything noticeable. It just marks URLs.
4316 If the <literal><link linkend="block">block</link></literal> action <emphasis>also applies</emphasis>,
4317 the presence or absence of this mark decides whether an HTML <quote>BLOCKED</quote>
4318 page, or an empty document will be sent to the client as a substitute for the blocked content.
4319 The <emphasis>empty</emphasis> document isn't literally empty, but actually contains a single space.
4326 <!-- Boolean, Parameterized, Multi-value -->
4328 <para>Boolean.</para>
4333 <term>Parameter:</term>
4345 Some browsers complain about syntax errors if JavaScript documents
4346 are blocked with <application>Privoxy's</application>
4347 default HTML page; this option can be used to silence them.
4348 And of course this action can also be used to eliminate the &my-app;
4349 BLOCKED message in frames.
4352 The content type for the empty document can be specified with
4353 <literal><link linkend="content-type-overwrite">content-type-overwrite{}</link></literal>,
4354 but usually this isn't necessary.
4360 <term>Example usage:</term>
4363 <screen># Block all documents on example.org that end with ".js",
4364 # but send an empty document instead of the usual HTML message.
4365 {+block{Blocked JavaScript} +handle-as-empty-document}
4375 <!-- ~~~~~ New section ~~~~~ -->
4376 <sect3 renderas="sect4" id="handle-as-image">
4377 <title>handle-as-image</title>
4381 <term>Typical use:</term>
4383 <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>
4388 <term>Effect:</term>
4391 This action alone doesn't do anything noticeable. It just marks URLs as images.
4392 If the <literal><link linkend="block">block</link></literal> action <emphasis>also applies</emphasis>,
4393 the presence or absence of this mark decides whether an HTML <quote>blocked</quote>
4394 page, or a replacement image (as determined by the <literal><link
4395 linkend="set-image-blocker">set-image-blocker</link></literal> action) will be sent to the
4396 client as a substitute for the blocked content.
4403 <!-- Boolean, Parameterized, Multi-value -->
4405 <para>Boolean.</para>
4410 <term>Parameter:</term>
4422 The below generic example section is actually part of <filename>default.action</filename>.
4423 It marks all URLs with well-known image file name extensions as images and should
4427 Users will probably only want to use the handle-as-image action in conjunction with
4428 <literal><link linkend="block">block</link></literal>, to block sources of banners, whose URLs don't
4429 reflect the file type, like in the second example section.
4432 Note that you cannot treat HTML pages as images in most cases. For instance, (in-line) ad
4433 frames require an HTML page to be sent, or they won't display properly.
4434 Forcing <literal>handle-as-image</literal> in this situation will not replace the
4435 ad frame with an image, but lead to error messages.
4441 <term>Example usage (sections):</term>
4444 <screen># Generic image extensions:
4447 /.*\.(gif|jpg|jpeg|png|bmp|ico)$
4449 # These don't look like images, but they're banners and should be
4450 # blocked as images:
4452 {+block{Nasty banners.} +handle-as-image}
4453 nasty-banner-server.example.com/junk.cgi\?output=trash
4462 <!-- ~~~~~ New section ~~~~~ -->
4463 <sect3 renderas="sect4" id="hide-accept-language">
4464 <title>hide-accept-language</title>
4470 <term>Typical use:</term>
4472 <para>Pretend to use different language settings.</para>
4477 <term>Effect:</term>
4480 Deletes or replaces the <quote>Accept-Language:</quote> HTTP header in client requests.
4487 <!-- Boolean, Parameterized, Multi-value -->
4489 <para>Parameterized.</para>
4494 <term>Parameter:</term>
4497 Keyword: <quote>block</quote>, or any user defined value.
4506 Faking the browser's language settings can be useful to make a
4507 foreign User-Agent set with
4508 <literal><link linkend="hide-user-agent">hide-user-agent</link></literal>
4512 However some sites with content in different languages check the
4513 <quote>Accept-Language:</quote> to decide which one to take by default.
4514 Sometimes it isn't possible to later switch to another language without
4515 changing the <quote>Accept-Language:</quote> header first.
4518 Therefore it's a good idea to either only change the
4519 <quote>Accept-Language:</quote> header to languages you understand,
4520 or to languages that aren't wide spread.
4523 Before setting the <quote>Accept-Language:</quote> header
4524 to a rare language, you should consider that it helps to
4525 make your requests unique and thus easier to trace.
4526 If you don't plan to change this header frequently,
4527 you should stick to a common language.
4533 <term>Example usage (section):</term>
4536 <screen># Pretend to use Canadian language settings.
4537 {+hide-accept-language{en-ca} \
4538 +hide-user-agent{Mozilla/5.0 (X11; U; OpenBSD i386; en-CA; rv:1.8.0.4) Gecko/20060628 Firefox/1.5.0.4} \
4548 <!-- ~~~~~ New section ~~~~~ -->
4549 <sect3 renderas="sect4" id="hide-content-disposition">
4550 <title>hide-content-disposition</title>
4556 <term>Typical use:</term>
4558 <para>Prevent download menus for content you prefer to view inside the browser.</para>
4563 <term>Effect:</term>
4566 Deletes or replaces the <quote>Content-Disposition:</quote> HTTP header set by some servers.
4573 <!-- Boolean, Parameterized, Multi-value -->
4575 <para>Parameterized.</para>
4580 <term>Parameter:</term>
4583 Keyword: <quote>block</quote>, or any user defined value.
4592 Some servers set the <quote>Content-Disposition:</quote> HTTP header for
4593 documents they assume you want to save locally before viewing them.
4594 The <quote>Content-Disposition:</quote> header contains the file name
4595 the browser is supposed to use by default.
4598 In most browsers that understand this header, it makes it impossible to
4599 <emphasis>just view</emphasis> the document, without downloading it first,
4600 even if it's just a simple text file or an image.
4603 Removing the <quote>Content-Disposition:</quote> header helps
4604 to prevent this annoyance, but some browsers additionally check the
4605 <quote>Content-Type:</quote> header, before they decide if they can
4606 display a document without saving it first. In these cases, you have
4607 to change this header as well, before the browser stops displaying
4611 It is also possible to change the server's file name suggestion
4612 to another one, but in most cases it isn't worth the time to set
4616 This action will probably be removed in the future,
4617 use server-header filters instead.
4623 <term>Example usage:</term>
4626 <screen># Disarm the download link in Sourceforge's patch tracker
4628 +content-type-overwrite{text/plain}\
4629 +hide-content-disposition{block} }
4630 .sourceforge.net/tracker/download\.php</screen>
4638 <!-- ~~~~~ New section ~~~~~ -->
4639 <sect3 renderas="sect4" id="hide-if-modified-since">
4640 <title>hide-if-modified-since</title>
4646 <term>Typical use:</term>
4648 <para>Prevent yet another way to track the user's steps between sessions.</para>
4653 <term>Effect:</term>
4656 Deletes the <quote>If-Modified-Since:</quote> HTTP client header or modifies its value.
4663 <!-- Boolean, Parameterized, Multi-value -->
4665 <para>Parameterized.</para>
4670 <term>Parameter:</term>
4673 Keyword: <quote>block</quote>, or a user defined value that specifies a range of hours.
4682 Removing this header is useful for filter testing, where you want to force a real
4683 reload instead of getting status code <quote>304</quote>, which would cause the
4684 browser to use a cached copy of the page.
4687 Instead of removing the header, <literal>hide-if-modified-since</literal> can
4688 also add or subtract a random amount of time to/from the header's value.
4689 You specify a range of minutes where the random factor should be chosen from and
4690 <application>Privoxy</application> does the rest. A negative value means
4691 subtracting, a positive value adding.
4694 Randomizing the value of the <quote>If-Modified-Since:</quote> makes
4695 it less likely that the server can use the time as a cookie replacement,
4696 but you will run into caching problems if the random range is too high.
4699 It is a good idea to only use a small negative value and let
4700 <literal><link linkend="overwrite-last-modified">overwrite-last-modified</link></literal>
4701 handle the greater changes.
4704 It is also recommended to use this action together with
4705 <literal><link linkend="crunch-if-none-match">crunch-if-none-match</link></literal>,
4706 otherwise it's more or less pointless.
4712 <term>Example usage (section):</term>
4715 <screen># Let the browser revalidate but make tracking based on the time less likely.
4716 {+hide-if-modified-since{-60} \
4717 +overwrite-last-modified{randomize} \
4718 +crunch-if-none-match}
4727 <!-- ~~~~~ New section ~~~~~ -->
4728 <sect3 renderas="sect4" id="hide-from-header">
4729 <title>hide-from-header</title>
4733 <term>Typical use:</term>
4735 <para>Keep your (old and ill) browser from telling web servers your email address</para>
4740 <term>Effect:</term>
4743 Deletes any existing <quote>From:</quote> HTTP header, or replaces it with the
4751 <!-- Boolean, Parameterized, Multi-value -->
4753 <para>Parameterized.</para>
4758 <term>Parameter:</term>
4761 Keyword: <quote>block</quote>, or any user defined value.
4770 The keyword <quote>block</quote> will completely remove the header
4771 (not to be confused with the <literal><link linkend="block">block</link></literal>
4775 Alternately, you can specify any value you prefer to be sent to the web
4776 server. If you do, it is a matter of fairness not to use any address that
4777 is actually used by a real person.
4780 This action is rarely needed, as modern web browsers don't send
4781 <quote>From:</quote> headers anymore.
4787 <term>Example usage:</term>
4790 <screen>+hide-from-header{block}</screen> or
4791 <screen>+hide-from-header{spam-me-senseless@sittingduck.example.com}</screen>
4799 <!-- ~~~~~ New section ~~~~~ -->
4800 <sect3 renderas="sect4" id="hide-referrer">
4801 <title>hide-referrer</title>
4802 <anchor id="hide-referer">
4805 <term>Typical use:</term>
4807 <para>Conceal which link you followed to get to a particular site</para>
4812 <term>Effect:</term>
4815 Deletes the <quote>Referer:</quote> (sic) HTTP header from the client request,
4816 or replaces it with a forged one.
4823 <!-- Boolean, Parameterized, Multi-value -->
4825 <para>Parameterized.</para>
4830 <term>Parameter:</term>
4834 <para><quote>conditional-block</quote> to delete the header completely if the host has changed.</para>
4837 <para><quote>conditional-forge</quote> to forge the header if the host has changed.</para>
4840 <para><quote>block</quote> to delete the header unconditionally.</para>
4843 <para><quote>forge</quote> to pretend to be coming from the homepage of the server we are talking to.</para>
4846 <para>Any other string to set a user defined referrer.</para>
4856 <literal>conditional-block</literal> is the only parameter,
4857 that isn't easily detected in the server's log file. If it blocks the
4858 referrer, the request will look like the visitor used a bookmark or
4859 typed in the address directly.
4862 Leaving the referrer unmodified for requests on the same host
4863 allows the server owner to see the visitor's <quote>click path</quote>,
4864 but in most cases she could also get that information by comparing
4865 other parts of the log file: for example the User-Agent if it isn't
4866 a very common one, or the user's IP address if it doesn't change between
4870 Always blocking the referrer, or using a custom one, can lead to
4871 failures on servers that check the referrer before they answer any
4872 requests, in an attempt to prevent their content from being
4873 embedded or linked to elsewhere.
4876 Both <literal>conditional-block</literal> and <literal>forge</literal>
4877 will work with referrer checks, as long as content and valid referring page
4878 are on the same host. Most of the time that's the case.
4881 <literal>hide-referer</literal> is an alternate spelling of
4882 <literal>hide-referrer</literal> and the two can be can be freely
4883 substituted with each other. (<quote>referrer</quote> is the
4884 correct English spelling, however the HTTP specification has a bug - it
4885 requires it to be spelled as <quote>referer</quote>.)
4891 <term>Example usage:</term>
4894 <screen>+hide-referrer{forge}</screen> or
4895 <screen>+hide-referrer{http://www.yahoo.com/}</screen>
4903 <!-- ~~~~~ New section ~~~~~ -->
4904 <sect3 renderas="sect4" id="hide-user-agent">
4905 <title>hide-user-agent</title>
4909 <term>Typical use:</term>
4911 <para>Try to conceal your type of browser and client operating system</para>
4916 <term>Effect:</term>
4919 Replaces the value of the <quote>User-Agent:</quote> HTTP header
4920 in client requests with the specified value.
4927 <!-- Boolean, Parameterized, Multi-value -->
4929 <para>Parameterized.</para>
4934 <term>Parameter:</term>
4937 Any user-defined string.
4947 This can lead to problems on web sites that depend on looking at this header in
4948 order to customize their content for different browsers (which, by the
4949 way, is <emphasis>NOT</emphasis> the right thing to do: good web sites
4950 work browser-independently).
4954 Using this action in multi-user setups or wherever different types of
4955 browsers will access the same <application>Privoxy</application> is
4956 <emphasis>not recommended</emphasis>. In single-user, single-browser
4957 setups, you might use it to delete your OS version information from
4958 the headers, because it is an invitation to exploit known bugs for your
4959 OS. It is also occasionally useful to forge this in order to access
4960 sites that won't let you in otherwise (though there may be a good
4961 reason in some cases).
4964 More information on known user-agent strings can be found at
4965 <ulink url="http://www.user-agents.org/">http://www.user-agents.org/</ulink>
4967 <ulink url="http://en.wikipedia.org/wiki/User_agent">http://en.wikipedia.org/wiki/User_agent</ulink>.
4973 <term>Example usage:</term>
4976 <screen>+hide-user-agent{Netscape 6.1 (X11; I; Linux 2.4.18 i686)}</screen>
4984 <!-- ~~~~~ New section ~~~~~ -->
4985 <sect3 renderas="sect4" id="limit-connect">
4986 <title>limit-connect</title>
4990 <term>Typical use:</term>
4992 <para>Prevent abuse of <application>Privoxy</application> as a TCP proxy relay or disable SSL for untrusted sites</para>
4997 <term>Effect:</term>
5000 Specifies to which ports HTTP CONNECT requests are allowable.
5007 <!-- Boolean, Parameterized, Multi-value -->
5009 <para>Parameterized.</para>
5014 <term>Parameter:</term>
5017 A comma-separated list of ports or port ranges (the latter using dashes, with the minimum
5018 defaulting to 0 and the maximum to 65K).
5027 By default, i.e. if no <literal>limit-connect</literal> action applies,
5028 <application>Privoxy</application> allows HTTP CONNECT requests to all
5029 ports. Use <literal>limit-connect</literal> if fine-grained control
5030 is desired for some or all destinations.
5033 The CONNECT methods exists in HTTP to allow access to secure websites
5034 (<quote>https://</quote> URLs) through proxies. It works very simply:
5035 the proxy connects to the server on the specified port, and then
5036 short-circuits its connections to the client and to the remote server.
5037 This means CONNECT-enabled proxies can be used as TCP relays very easily.
5040 <application>Privoxy</application> relays HTTPS traffic without seeing
5041 the decoded content. Websites can leverage this limitation to circumvent &my-app;'s
5042 filters. By specifying an invalid port range you can disable HTTPS entirely.
5048 <term>Example usages:</term>
5050 <!-- I had trouble getting the spacing to look right in my browser -->
5051 <!-- I probably have the wrong font setup, bollocks. -->
5052 <!-- Apparently the emphasis tag uses a proportional font no matter what -->
5054 <screen>+limit-connect{443} # Port 443 is OK.
5055 +limit-connect{80,443} # Ports 80 and 443 are OK.
5056 +limit-connect{-3, 7, 20-100, 500-} # Ports less than 3, 7, 20 to 100 and above 500 are OK.
5057 +limit-connect{-} # All ports are OK
5058 +limit-connect{,} # No HTTPS/SSL traffic is allowed</screen>
5066 <!-- ~~~~~ New section ~~~~~ -->
5067 <sect3 renderas="sect4" id="limit-cookie-lifetime">
5068 <title>limit-cookie-lifetime</title>
5072 <term>Typical use:</term>
5074 <para>Limit the lifetime of HTTP cookies to a couple of minutes or hours.</para>
5079 <term>Effect:</term>
5082 Overwrites the expires field in Set-Cookie server headers if it's above the specified limit.
5089 <!-- Boolean, Parameterized, Multi-value -->
5091 <para>Parameterized.</para>
5096 <term>Parameter:</term>
5099 The lifetime limit in minutes, or 0.
5108 This action reduces the lifetime of HTTP cookies coming from the
5109 server to the specified number of minutes, starting from the time
5110 the cookie passes Privoxy.
5113 Cookies with a lifetime below the limit are not modified.
5114 The lifetime of session cookies is set to the specified limit.
5117 The effect of this action depends on the server.
5120 In case of servers which refresh their cookies with each response
5121 (or at least frequently), the lifetime limit set by this action
5123 Thus, a session associated with the cookie continues to work with
5124 this action enabled, as long as a new request is made before the
5125 last limit set is reached.
5128 However, some servers send their cookies once, with a lifetime of several
5129 years (the year 2037 is a popular choice), and do not refresh them
5130 until a certain event in the future, for example the user logging out.
5131 In this case this action may limit the absolute lifetime of the session,
5132 even if requests are made frequently.
5135 If the parameter is <quote>0</quote>, this action behaves like
5136 <literal><link linkend="session-cookies-only">session-cookies-only</link></literal>.
5142 <term>Example usages:</term>
5145 <screen>+limit-cookie-lifetime{60}
5153 <!-- ~~~~~ New section ~~~~~ -->
5154 <sect3 renderas="sect4" id="prevent-compression">
5155 <title>prevent-compression</title>
5159 <term>Typical use:</term>
5162 Ensure that servers send the content uncompressed, so it can be
5163 passed through <literal><link linkend="filter">filter</link></literal>s.
5169 <term>Effect:</term>
5172 Removes the Accept-Encoding header which can be used to ask for compressed transfer.
5179 <!-- Boolean, Parameterized, Multi-value -->
5181 <para>Boolean.</para>
5186 <term>Parameter:</term>
5198 More and more websites send their content compressed by default, which
5199 is generally a good idea and saves bandwidth. But the <literal><link
5200 linkend="filter">filter</link></literal> and
5201 <literal><link linkend="deanimate-gifs">deanimate-gifs</link></literal>
5202 actions need access to the uncompressed data.
5205 When compiled with zlib support (available since &my-app; 3.0.7), content that should be
5206 filtered is decompressed on-the-fly and you don't have to worry about this action.
5207 If you are using an older &my-app; version, or one that hasn't been compiled with zlib
5208 support, this action can be used to convince the server to send the content uncompressed.
5211 Most text-based instances compress very well, the size is seldom decreased by less than 50%,
5212 for markup-heavy instances like news feeds saving more than 90% of the original size isn't
5216 Not using compression will therefore slow down the transfer, and you should only
5217 enable this action if you really need it. As of &my-app; 3.0.7 it's disabled in all
5218 predefined action settings.
5221 Note that some (rare) ill-configured sites don't handle requests for uncompressed
5222 documents correctly. Broken PHP applications tend to send an empty document body,
5223 some IIS versions only send the beginning of the content. If you enable
5224 <literal>prevent-compression</literal> per default, you might want to add
5225 exceptions for those sites. See the example for how to do that.
5231 <term>Example usage (sections):</term>
5235 # Selectively turn off compression, and enable a filter
5237 { +filter{tiny-textforms} +prevent-compression }
5238 # Match only these sites
5243 # Or instead, we could set a universal default:
5245 { +prevent-compression }
5248 # Then maybe make exceptions for broken sites:
5250 { -prevent-compression }
5251 .compusa.com/</screen>
5260 <!-- ~~~~~ New section ~~~~~ -->
5261 <sect3 renderas="sect4" id="overwrite-last-modified">
5262 <title>overwrite-last-modified</title>
5268 <term>Typical use:</term>
5270 <para>Prevent yet another way to track the user's steps between sessions.</para>
5275 <term>Effect:</term>
5278 Deletes the <quote>Last-Modified:</quote> HTTP server header or modifies its value.
5285 <!-- Boolean, Parameterized, Multi-value -->
5287 <para>Parameterized.</para>
5292 <term>Parameter:</term>
5295 One of the keywords: <quote>block</quote>, <quote>reset-to-request-time</quote>
5296 and <quote>randomize</quote>
5305 Removing the <quote>Last-Modified:</quote> header is useful for filter
5306 testing, where you want to force a real reload instead of getting status
5307 code <quote>304</quote>, which would cause the browser to reuse the old
5308 version of the page.
5311 The <quote>randomize</quote> option overwrites the value of the
5312 <quote>Last-Modified:</quote> header with a randomly chosen time
5313 between the original value and the current time. In theory the server
5314 could send each document with a different <quote>Last-Modified:</quote>
5315 header to track visits without using cookies. <quote>Randomize</quote>
5316 makes it impossible and the browser can still revalidate cached documents.
5319 <quote>reset-to-request-time</quote> overwrites the value of the
5320 <quote>Last-Modified:</quote> header with the current time. You could use
5321 this option together with
5322 <literal><link linkend="hide-if-modified-since">hide-if-modified-since</link></literal>
5323 to further customize your random range.
5326 The preferred parameter here is <quote>randomize</quote>. It is safe
5327 to use, as long as the time settings are more or less correct.
5328 If the server sets the <quote>Last-Modified:</quote> header to the time
5329 of the request, the random range becomes zero and the value stays the same.
5330 Therefore you should later randomize it a second time with
5331 <literal><link linkend="hide-if-modified-since">hided-if-modified-since</link></literal>,
5335 It is also recommended to use this action together with
5336 <literal><link linkend="crunch-if-none-match">crunch-if-none-match</link></literal>.
5342 <term>Example usage:</term>
5345 <screen># Let the browser revalidate without being tracked across sessions
5346 { +hide-if-modified-since{-60} \
5347 +overwrite-last-modified{randomize} \
5348 +crunch-if-none-match}
5357 <!-- ~~~~~ New section ~~~~~ -->
5358 <sect3 renderas="sect4" id="redirect">
5359 <title>redirect</title>
5365 <term>Typical use:</term>
5368 Redirect requests to other sites.
5374 <term>Effect:</term>
5377 Convinces the browser that the requested document has been moved
5378 to another location and the browser should get it from there.
5385 <!-- Boolean, Parameterized, Multi-value -->
5387 <para>Parameterized</para>
5392 <term>Parameter:</term>
5395 An absolute URL or a single pcrs command.
5404 Requests to which this action applies are answered with a
5405 HTTP redirect to URLs of your choosing. The new URL is
5406 either provided as parameter, or derived by applying a
5407 single pcrs command to the original URL.
5410 The syntax for pcrs commands is documented in the
5411 <link linkend="filter-file">filter file</link> section.
5414 Requests can't be blocked and redirected at the same time,
5415 applying this action together with
5416 <literal><link linkend="block">block</link></literal>
5417 is a configuration error. Currently the request is blocked
5418 and an error message logged, the behavior may change in the
5419 future and result in Privoxy rejecting the action file.
5422 This action can be combined with
5423 <literal><link linkend="fast-redirects">fast-redirects{check-decoded-url}</link></literal>
5424 to redirect to a decoded version of a rewritten URL.
5427 Use this action carefully, make sure not to create redirection loops
5428 and be aware that using your own redirects might make it
5429 possible to fingerprint your requests.
5432 In case of problems with your redirects, or simply to watch
5433 them working, enable <link linkend="DEBUG">debug 128</link>.
5439 <term>Example usages:</term>
5442 <screen># Replace example.com's style sheet with another one
5443 { +redirect{http://localhost/css-replacements/example.com.css} }
5444 example.com/stylesheet\.css
5446 # Create a short, easy to remember nickname for a favorite site
5447 # (relies on the browser to accept and forward invalid URLs to &my-app;)
5448 { +redirect{http://www.privoxy.org/user-manual/actions-file.html} }
5451 # Always use the expanded view for Undeadly.org articles
5452 # (Note the $ at the end of the URL pattern to make sure
5453 # the request for the rewritten URL isn't redirected as well)
5454 {+redirect{s@$@&mode=expanded@}}
5455 undeadly.org/cgi\?action=article&sid=\d*$
5457 # Redirect Google search requests to MSN
5458 {+redirect{s@^http://[^/]*/search\?q=([^&]*).*@http://search.msn.com/results.aspx?q=$1@}}
5461 # Redirect MSN search requests to Yahoo
5462 {+redirect{s@^http://[^/]*/results\.aspx\?q=([^&]*).*@http://search.yahoo.com/search?p=$1@}}
5463 search.msn.com//results\.aspx\?q=
5465 # Redirect http://example.com/&bla=fasel&toChange=foo (and any other value but "bar")
5466 # to http://example.com/&bla=fasel&toChange=bar
5468 # The URL pattern makes sure that the following request isn't redirected again.
5469 {+redirect{s@toChange=[^&]+@toChange=bar@}}
5470 example.com/.*toChange=(?!bar)
5472 # Add a shortcut to look up illumos bugs
5473 {+redirect{s@^http://i([0-9]+)/.*@https://www.illumos.org/issues/$1@}}
5474 # Redirected URL = http://i4974/
5475 # Redirect Destination = https://www.illumos.org/issues/4974
5476 i[0-9][0-9][0-9][0-9]*/
5478 # Redirect remote requests for this manual
5479 # to the local version delivered by Privoxy
5480 {+redirect{s@^http://www@http://config@}}
5481 www.privoxy.org/user-manual/</screen>
5490 <!-- ~~~~~ New section ~~~~~ -->
5491 <sect3 renderas="sect4" id="server-header-filter">
5492 <title>server-header-filter</title>
5496 <term>Typical use:</term>
5499 Rewrite or remove single server headers.
5505 <term>Effect:</term>
5508 All server headers to which this action applies are filtered on-the-fly
5509 through the specified regular expression based substitutions.
5516 <!-- boolean, parameterized, Multi-value -->
5518 <para>Multi-value.</para>
5523 <term>Parameter:</term>
5526 The name of a server-header filter, as defined in one of the
5527 <link linkend="filter-file">filter files</link>.
5536 Server-header filters are applied to each header on its own, not to
5537 all at once. This makes it easier to diagnose problems, but on the downside
5538 you can't write filters that only change header x if header y's value is z.
5539 You can do that by using tags though.
5542 Server-header filters are executed after the other header actions have finished
5543 and use their output as input.
5546 Please refer to the <link linkend="filter-file">filter file chapter</link>
5547 to learn which server-header filters are available by default, and how to
5554 <term>Example usage (section):</term>
5558 {+server-header-filter{html-to-xml}}
5559 example.org/xml-instance-that-is-delivered-as-html
5561 {+server-header-filter{xml-to-html}}
5562 example.org/instance-that-is-delivered-as-xml-but-is-not
5572 <!-- ~~~~~ New section ~~~~~ -->
5573 <sect3 renderas="sect4" id="server-header-tagger">
5574 <title>server-header-tagger</title>
5578 <term>Typical use:</term>
5581 Enable or disable filters based on the Content-Type header.
5587 <term>Effect:</term>
5590 Server headers to which this action applies are filtered on-the-fly through
5591 the specified regular expression based substitutions, the result is used as
5599 <!-- boolean, parameterized, Multi-value -->
5601 <para>Multi-value.</para>
5606 <term>Parameter:</term>
5609 The name of a server-header tagger, as defined in one of the
5610 <link linkend="filter-file">filter files</link>.
5619 Server-header taggers are applied to each header on its own,
5620 and as the header isn't modified, each tagger <quote>sees</quote>
5624 Server-header taggers are executed before all other header actions
5625 that modify server headers. Their tags can be used to control
5626 all of the other server-header actions, the content filters
5627 and the crunch actions (<link linkend="redirect">redirect</link>
5628 and <link linkend="block">block</link>).
5631 Obviously crunching based on tags created by server-header taggers
5632 doesn't prevent the request from showing up in the server's log file.
5639 <term>Example usage (section):</term>
5643 # Tag every request with the content type declared by the server
5644 {+server-header-tagger{content-type}}
5647 # If the response has a tag starting with 'image/' enable an external
5648 # filter that only applies to images.
5650 # Note that the filter is not available by default, it's just a
5651 # <literal><link linkend="external-filter-syntax">silly example</link></literal>.
5652 {+external-filter{rotate-image} +force-text-mode}
5663 <!-- ~~~~~ New section ~~~~~ -->
5664 <sect3 renderas="sect4" id="session-cookies-only">
5665 <title>session-cookies-only</title>
5669 <term>Typical use:</term>
5672 Allow only temporary <quote>session</quote> cookies (for the current
5673 browser session <emphasis>only</emphasis>).
5679 <term>Effect:</term>
5682 Deletes the <quote>expires</quote> field from <quote>Set-Cookie:</quote>
5683 server headers. Most browsers will not store such cookies permanently and
5684 forget them in between sessions.
5691 <!-- Boolean, Parameterized, Multi-value -->
5693 <para>Boolean.</para>
5698 <term>Parameter:</term>
5710 This is less strict than <literal><link linkend="crunch-incoming-cookies">crunch-incoming-cookies</link></literal> /
5711 <literal><link linkend="crunch-outgoing-cookies">crunch-outgoing-cookies</link></literal> and allows you to browse
5712 websites that insist or rely on setting cookies, without compromising your privacy too badly.
5715 Most browsers will not permanently store cookies that have been processed by
5716 <literal>session-cookies-only</literal> and will forget about them between sessions.
5717 This makes profiling cookies useless, but won't break sites which require cookies so
5718 that you can log in for transactions. This is generally turned on for all
5719 sites, and is the recommended setting.
5722 It makes <emphasis>no sense at all</emphasis> to use <literal>session-cookies-only</literal>
5723 together with <literal><link linkend="crunch-incoming-cookies">crunch-incoming-cookies</link></literal> or
5724 <literal><link linkend="crunch-outgoing-cookies">crunch-outgoing-cookies</link></literal>. If you do, cookies
5725 will be plainly killed.
5728 Note that it is up to the browser how it handles such cookies without an <quote>expires</quote>
5729 field. If you use an exotic browser, you might want to try it out to be sure.
5732 This setting also has no effect on cookies that may have been stored
5733 previously by the browser before starting <application>Privoxy</application>.
5734 These would have to be removed manually.
5737 <application>Privoxy</application> also uses
5738 the <link linkend="filter-content-cookies">content-cookies filter</link>
5739 to block some types of cookies. Content cookies are not effected by
5740 <literal>session-cookies-only</literal>.
5746 <term>Example usage:</term>
5749 <screen>+session-cookies-only</screen>
5757 <!-- ~~~~~ New section ~~~~~ -->
5758 <sect3 renderas="sect4" id="set-image-blocker">
5759 <title>set-image-blocker</title>
5763 <term>Typical use:</term>
5765 <para>Choose the replacement for blocked images</para>
5770 <term>Effect:</term>
5773 This action alone doesn't do anything noticeable. If <emphasis>both</emphasis>
5774 <literal><link linkend="block">block</link></literal> <emphasis>and</emphasis> <literal><link
5775 linkend="handle-as-image">handle-as-image</link></literal> <emphasis>also</emphasis>
5776 apply, i.e. if the request is to be blocked as an image,
5777 <emphasis>then</emphasis> the parameter of this action decides what will be
5778 sent as a replacement.
5785 <!-- Boolean, Parameterized, Multi-value -->
5787 <para>Parameterized.</para>
5792 <term>Parameter:</term>
5797 <quote>pattern</quote> to send a built-in checkerboard pattern image. The image is visually
5798 decent, scales very well, and makes it obvious where banners were busted.
5803 <quote>blank</quote> to send a built-in transparent image. This makes banners disappear
5804 completely, but makes it hard to detect where <application>Privoxy</application> has blocked
5805 images on a given page and complicates troubleshooting if <application>Privoxy</application>
5806 has blocked innocent images, like navigation icons.
5811 <quote><replaceable class="parameter">target-url</replaceable></quote> to
5812 send a redirect to <replaceable class="parameter">target-url</replaceable>. You can redirect
5813 to any image anywhere, even in your local filesystem via <quote>file:///</quote> URL.
5814 (But note that not all browsers support redirecting to a local file system).
5817 A good application of redirects is to use special <application>Privoxy</application>-built-in
5818 URLs, which send the built-in images, as <replaceable class="parameter">target-url</replaceable>.
5819 This has the same visual effect as specifying <quote>blank</quote> or <quote>pattern</quote> in
5820 the first place, but enables your browser to cache the replacement image, instead of requesting
5821 it over and over again.
5832 The URLs for the built-in images are <quote>http://config.privoxy.org/send-banner?type=<replaceable
5833 class="parameter">type</replaceable></quote>, where <replaceable class="parameter">type</replaceable> is
5834 either <quote>blank</quote> or <quote>pattern</quote>.
5837 There is a third (advanced) type, called <quote>auto</quote>. It is <emphasis>NOT</emphasis> to be
5838 used in <literal>set-image-blocker</literal>, but meant for use from <link linkend="filter-file">filters</link>.
5839 Auto will select the type of image that would have applied to the referring page, had it been an image.
5845 <term>Example usage:</term>
5851 <screen>+set-image-blocker{pattern}</screen>
5854 Redirect to the BSD daemon:
5857 <screen>+set-image-blocker{http://www.freebsd.org/gifs/dae_up3.gif}</screen>
5860 Redirect to the built-in pattern for better caching:
5863 <screen>+set-image-blocker{http://config.privoxy.org/send-banner?type=pattern}</screen>
5871 <!-- ~~~~~ New section ~~~~~ -->
5873 <title>Summary</title>
5875 Note that many of these actions have the potential to cause a page to
5876 misbehave, possibly even not to display at all. There are many ways
5877 a site designer may choose to design his site, and what HTTP header
5878 content, and other criteria, he may depend on. There is no way to have hard
5879 and fast rules for all sites. See the <link
5880 linkend="ACTIONSANAT">Appendix</link> for a brief example on troubleshooting
5886 <!-- ~~~~~ New section ~~~~~ -->
5887 <sect2 id="aliases">
5888 <title>Aliases</title>
5890 Custom <quote>actions</quote>, known to <application>Privoxy</application>
5891 as <quote>aliases</quote>, can be defined by combining other actions.
5892 These can in turn be invoked just like the built-in actions.
5893 Currently, an alias name can contain any character except space, tab,
5895 <quote>{</quote> and <quote>}</quote>, but we <emphasis>strongly
5896 recommend</emphasis> that you only use <quote>a</quote> to <quote>z</quote>,
5897 <quote>0</quote> to <quote>9</quote>, <quote>+</quote>, and <quote>-</quote>.
5898 Alias names are not case sensitive, and are not required to start with a
5899 <quote>+</quote> or <quote>-</quote> sign, since they are merely textually
5903 Aliases can be used throughout the actions file, but they <emphasis>must be
5904 defined in a special section at the top of the file!</emphasis>
5905 And there can only be one such section per actions file. Each actions file may
5906 have its own alias section, and the aliases defined in it are only visible
5910 There are two main reasons to use aliases: One is to save typing for frequently
5911 used combinations of actions, the other one is a gain in flexibility: If you
5912 decide once how you want to handle shops by defining an alias called
5913 <quote>shop</quote>, you can later change your policy on shops in
5914 <emphasis>one</emphasis> place, and your changes will take effect everywhere
5915 in the actions file where the <quote>shop</quote> alias is used. Calling aliases
5916 by their purpose also makes your actions files more readable.
5919 Currently, there is one big drawback to using aliases, though:
5920 <application>Privoxy</application>'s built-in web-based action file
5921 editor honors aliases when reading the actions files, but it expands
5922 them before writing. So the effects of your aliases are of course preserved,
5923 but the aliases themselves are lost when you edit sections that use aliases
5928 Now let's define some aliases...
5933 # Useful custom aliases we can use later.
5935 # Note the (required!) section header line and that this section
5936 # must be at the top of the actions file!
5940 # These aliases just save typing later:
5941 # (Note that some already use other aliases!)
5943 +crunch-all-cookies = +<link linkend="CRUNCH-INCOMING-COOKIES">crunch-incoming-cookies</link> +<link linkend="CRUNCH-OUTGOING-COOKIES">crunch-outgoing-cookies</link>
5944 -crunch-all-cookies = -<link linkend="CRUNCH-INCOMING-COOKIES">crunch-incoming-cookies</link> -<link linkend="CRUNCH-OUTGOING-COOKIES">crunch-outgoing-cookies</link>
5945 +block-as-image = +block{Blocked image.} +handle-as-image
5946 allow-all-cookies = -crunch-all-cookies -<link linkend="SESSION-COOKIES-ONLY">session-cookies-only</link> -<link linkend="FILTER-CONTENT-COOKIES">filter{content-cookies}</link>
5948 # These aliases define combinations of actions
5949 # that are useful for certain types of sites:
5951 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>
5953 shop = -crunch-all-cookies -<link linkend="FILTER-ALL-POPUPS">filter{all-popups}</link>
5955 # Short names for other aliases, for really lazy people ;-)
5957 c0 = +crunch-all-cookies
5958 c1 = -crunch-all-cookies</screen>
5962 ...and put them to use. These sections would appear in the lower part of an
5963 actions file and define exceptions to the default actions (as specified further
5964 up for the <quote>/</quote> pattern):
5969 # These sites are either very complex or very keen on
5970 # user data and require minimal interference to work:
5973 .office.microsoft.com
5974 .windowsupdate.microsoft.com
5975 # Gmail is really mail.google.com, not gmail.com
5979 # Allow cookies (for setting and retrieving your customer data)
5983 .worldpay.com # for quietpc.com
5986 # These shops require pop-ups:
5988 {-filter{all-popups} -filter{unsolicited-popups}}
5990 .overclockers.co.uk</screen>
5994 Aliases like <quote>shop</quote> and <quote>fragile</quote> are typically used for
5995 <quote>problem</quote> sites that require more than one action to be disabled
5996 in order to function properly.
6002 <!-- ~~~~~ New section ~~~~~ -->
6003 <sect2 id="act-examples">
6004 <title>Actions Files Tutorial</title>
6006 The above chapters have shown <link linkend="actions-file">which actions files
6007 there are and how they are organized</link>, how actions are <link
6008 linkend="actions">specified</link> and <link linkend="actions-apply">applied
6009 to URLs</link>, how <link linkend="af-patterns">patterns</link> work, and how to
6010 define and use <link linkend="aliases">aliases</link>. Now, let's look at an
6011 example <filename>match-all.action</filename>, <filename>default.action</filename>
6012 and <filename>user.action</filename> file and see how all these pieces come together:
6016 <title>match-all.action</title>
6018 Remember <emphasis>all actions are disabled when matching starts</emphasis>,
6019 so we have to explicitly enable the ones we want.
6023 While the <filename>match-all.action</filename> file only contains a
6024 single section, it is probably the most important one. It has only one
6025 pattern, <quote><literal>/</literal></quote>, but this pattern
6026 <link linkend="af-patterns">matches all URLs</link>. Therefore, the set of
6027 actions used in this <quote>default</quote> section <emphasis>will
6028 be applied to all requests as a start</emphasis>. It can be partly or
6029 wholly overridden by other actions files like <filename>default.action</filename>
6030 and <filename>user.action</filename>, but it will still be largely responsible
6031 for your overall browsing experience.
6035 Again, at the start of matching, all actions are disabled, so there is
6036 no need to disable any actions here. (Remember: a <quote>+</quote>
6037 preceding the action name enables the action, a <quote>-</quote> disables!).
6038 Also note how this long line has been made more readable by splitting it into
6039 multiple lines with line continuation.
6045 +<link linkend="CHANGE-X-FORWARDED-FOR">change-x-forwarded-for{block}</link> \
6046 +<link linkend="HIDE-FROM-HEADER">hide-from-header{block}</link> \
6047 +<link linkend="SET-IMAGE-BLOCKER">set-image-blocker{pattern}</link> \
6054 The default behavior is now set.
6059 <title>default.action</title>
6062 If you aren't a developer, there's no need for you to edit the
6063 <filename>default.action</filename> file. It is maintained by
6064 the &my-app; developers and if you disagree with some of the
6065 sections, you should overrule them in your <filename>user.action</filename>.
6069 Understanding the <filename>default.action</filename> file can
6070 help you with your <filename>user.action</filename>, though.
6074 The first section in this file is a special section for internal use
6075 that prevents older &my-app; versions from reading the file:
6080 ##########################################################################
6081 # Settings -- Don't change! For internal Privoxy use ONLY.
6082 ##########################################################################
6084 for-privoxy-version=3.0.11</screen>
6088 After that comes the (optional) alias section. We'll use the example
6089 section from the above <link linkend="aliases">chapter on aliases</link>,
6090 that also explains why and how aliases are used:
6095 ##########################################################################
6097 ##########################################################################
6100 # These aliases just save typing later:
6101 # (Note that some already use other aliases!)
6103 +crunch-all-cookies = +<link linkend="CRUNCH-INCOMING-COOKIES">crunch-incoming-cookies</link> +<link linkend="CRUNCH-OUTGOING-COOKIES">crunch-outgoing-cookies</link>
6104 -crunch-all-cookies = -<link linkend="CRUNCH-INCOMING-COOKIES">crunch-incoming-cookies</link> -<link linkend="CRUNCH-OUTGOING-COOKIES">crunch-outgoing-cookies</link>
6105 +block-as-image = +block{Blocked image.} +handle-as-image
6106 mercy-for-cookies = -crunch-all-cookies -<link linkend="SESSION-COOKIES-ONLY">session-cookies-only</link> -<link linkend="FILTER-CONTENT-COOKIES">filter{content-cookies}</link>
6108 # These aliases define combinations of actions
6109 # that are useful for certain types of sites:
6111 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>
6112 shop = -crunch-all-cookies -<link linkend="FILTER-ALL-POPUPS">filter{all-popups}</link></screen>
6116 The first of our specialized sections is concerned with <quote>fragile</quote>
6117 sites, i.e. sites that require minimum interference, because they are either
6118 very complex or very keen on tracking you (and have mechanisms in place that
6119 make them unusable for people who avoid being tracked). We will simply use
6120 our pre-defined <literal>fragile</literal> alias instead of stating the list
6121 of actions explicitly:
6126 ##########################################################################
6127 # Exceptions for sites that'll break under the default action set:
6128 ##########################################################################
6130 # "Fragile" Use a minimum set of actions for these sites (see alias above):
6133 .office.microsoft.com # surprise, surprise!
6134 .windowsupdate.microsoft.com
6135 mail.google.com</screen>
6139 Shopping sites are not as fragile, but they typically
6140 require cookies to log in, and pop-up windows for shopping
6141 carts or item details. Again, we'll use a pre-defined alias:
6150 .worldpay.com # for quietpc.com
6152 .scan.co.uk</screen>
6156 The <literal><link linkend="FAST-REDIRECTS">fast-redirects</link></literal>
6157 action, which may have been enabled in <filename>match-all.action</filename>,
6158 breaks some sites. So disable it for popular sites where we know it misbehaves:
6163 { -<link linkend="FAST-REDIRECTS">fast-redirects</link> }
6167 .altavista.com/.*(like|url|link):http
6168 .altavista.com/trans.*urltext=http
6169 .nytimes.com</screen>
6173 It is important that <application>Privoxy</application> knows which
6174 URLs belong to images, so that <emphasis>if</emphasis> they are to
6175 be blocked, a substitute image can be sent, rather than an HTML page.
6176 Contacting the remote site to find out is not an option, since it
6177 would destroy the loading time advantage of banner blocking, and it
6178 would feed the advertisers information about you. We can mark any
6179 URL as an image with the <literal><link
6180 linkend="handle-as-image">handle-as-image</link></literal> action,
6181 and marking all URLs that end in a known image file extension is a
6187 ##########################################################################
6189 ##########################################################################
6191 # Define which file types will be treated as images, in case they get
6192 # blocked further down this file:
6194 { +<link linkend="HANDLE-AS-IMAGE">handle-as-image</link> }
6195 /.*\.(gif|jpe?g|png|bmp|ico)$</screen>
6199 And then there are known banner sources. They often use scripts to
6200 generate the banners, so it won't be visible from the URL that the
6201 request is for an image. Hence we block them <emphasis>and</emphasis>
6202 mark them as images in one go, with the help of our
6203 <literal>+block-as-image</literal> alias defined above. (We could of
6204 course just as well use <literal>+<link linkend="block">block</link>
6205 +<link linkend="handle-as-image">handle-as-image</link></literal> here.)
6206 Remember that the type of the replacement image is chosen by the
6207 <literal><link linkend="set-image-blocker">set-image-blocker</link></literal>
6208 action. Since all URLs have matched the default section with its
6209 <literal>+<link linkend="set-image-blocker">set-image-blocker</link>{pattern}</literal>
6210 action before, it still applies and needn't be repeated:
6215 # Known ad generators:
6220 .ad.*.doubleclick.net
6221 .a.yimg.com/(?:(?!/i/).)*$
6222 .a[0-9].yimg.com/(?:(?!/i/).)*$
6228 One of the most important jobs of <application>Privoxy</application>
6229 is to block banners. Many of these can be <quote>blocked</quote>
6230 by the <literal><link linkend="filter">filter</link>{banners-by-size}</literal>
6231 action, which we enabled above, and which deletes the references to banner
6232 images from the pages while they are loaded, so the browser doesn't request
6233 them anymore, and hence they don't need to be blocked here. But this naturally
6234 doesn't catch all banners, and some people choose not to use filters, so we
6235 need a comprehensive list of patterns for banner URLs here, and apply the
6236 <literal><link linkend="block">block</link></literal> action to them.
6239 First comes many generic patterns, which do most of the work, by
6240 matching typical domain and path name components of banners. Then comes
6241 a list of individual patterns for specific sites, which is omitted here
6242 to keep the example short:
6247 ##########################################################################
6248 # Block these fine banners:
6249 ##########################################################################
6250 { <link linkend="BLOCK">+block{Banner ads.}</link> }
6258 /.*count(er)?\.(pl|cgi|exe|dll|asp|php[34]?)
6259 /(?:.*/)?(publicite|werbung|rekla(ma|me|am)|annonse|maino(kset|nta|s)?)/
6261 # Site-specific patterns (abbreviated):
6263 .hitbox.com</screen>
6267 It's quite remarkable how many advertisers actually call their banner
6268 servers ads.<replaceable>company</replaceable>.com, or call the directory
6269 in which the banners are stored simply <quote>banners</quote>. So the above
6270 generic patterns are surprisingly effective.
6273 But being very generic, they necessarily also catch URLs that we don't want
6274 to block. The pattern <literal>.*ads.</literal> e.g. catches
6275 <quote>nasty-<emphasis>ads</emphasis>.nasty-corp.com</quote> as intended,
6276 but also <quote>downlo<emphasis>ads</emphasis>.sourcefroge.net</quote> or
6277 <quote><emphasis>ads</emphasis>l.some-provider.net.</quote> So here come some
6278 well-known exceptions to the <literal>+<link linkend="BLOCK">block</link></literal>
6282 Note that these are exceptions to exceptions from the default! Consider the URL
6283 <quote>downloads.sourcefroge.net</quote>: Initially, all actions are deactivated,
6284 so it wouldn't get blocked. Then comes the defaults section, which matches the
6285 URL, but just deactivates the <literal><link linkend="BLOCK">block</link></literal>
6286 action once again. Then it matches <literal>.*ads.</literal>, an exception to the
6287 general non-blocking policy, and suddenly
6288 <literal><link linkend="BLOCK">+block</link></literal> applies. And now, it'll match
6289 <literal>.*loads.</literal>, where <literal><link linkend="BLOCK">-block</link></literal>
6290 applies, so (unless it matches <emphasis>again</emphasis> further down) it ends up
6291 with no <literal><link linkend="BLOCK">block</link></literal> action applying.
6296 ##########################################################################
6297 # Save some innocent victims of the above generic block patterns:
6298 ##########################################################################
6302 { -<link linkend="BLOCK">block</link> }
6303 adv[io]*. # (for advogato.org and advice.*)
6304 adsl. # (has nothing to do with ads)
6305 adobe. # (has nothing to do with ads either)
6306 ad[ud]*. # (adult.* and add.*)
6307 .edu # (universities don't host banners (yet!))
6308 .*loads. # (downloads, uploads etc)
6316 www.globalintersec.com/adv # (adv = advanced)
6317 www.ugu.com/sui/ugu/adv</screen>
6321 Filtering source code can have nasty side effects,
6322 so make an exception for our friends at sourceforge.net,
6323 and all paths with <quote>cvs</quote> in them. Note that
6324 <literal>-<link linkend="FILTER">filter</link></literal>
6325 disables <emphasis>all</emphasis> filters in one fell swoop!
6330 # Don't filter code!
6332 { -<link linkend="FILTER">filter</link> }
6337 .sourceforge.net</screen>
6341 The actual <filename>default.action</filename> is of course much more
6342 comprehensive, but we hope this example made clear how it works.
6347 <sect3><title>user.action</title>
6350 So far we are painting with a broad brush by setting general policies,
6351 which would be a reasonable starting point for many people. Now,
6352 you might want to be more specific and have customized rules that
6353 are more suitable to your personal habits and preferences. These would
6354 be for narrowly defined situations like your ISP or your bank, and should
6355 be placed in <filename>user.action</filename>, which is parsed after all other
6356 actions files and hence has the last word, over-riding any previously
6357 defined actions. <filename>user.action</filename> is also a
6358 <emphasis>safe</emphasis> place for your personal settings, since
6359 <filename>default.action</filename> is actively maintained by the
6360 <application>Privoxy</application> developers and you'll probably want
6361 to install updated versions from time to time.
6365 So let's look at a few examples of things that one might typically do in
6366 <filename>user.action</filename>:
6370 <!-- brief sample user.action here -->
6374 # My user.action file. <fred@example.com></screen>
6378 As <link linkend="aliases">aliases</link> are local to the actions
6379 file that they are defined in, you can't use the ones from
6380 <filename>default.action</filename>, unless you repeat them here:
6385 # Aliases are local to the file they are defined in.
6386 # (Re-)define aliases for this file:
6390 # These aliases just save typing later, and the alias names should
6391 # be self explanatory.
6393 +crunch-all-cookies = +crunch-incoming-cookies +crunch-outgoing-cookies
6394 -crunch-all-cookies = -crunch-incoming-cookies -crunch-outgoing-cookies
6395 allow-all-cookies = -crunch-all-cookies -session-cookies-only
6396 allow-popups = -filter{all-popups}
6397 +block-as-image = +block{Blocked as image.} +handle-as-image
6398 -block-as-image = -block
6400 # These aliases define combinations of actions that are useful for
6401 # certain types of sites:
6403 fragile = -block -crunch-all-cookies -filter -fast-redirects -hide-referrer
6404 shop = -crunch-all-cookies allow-popups
6406 # Allow ads for selected useful free sites:
6408 allow-ads = -block -filter{banners-by-size} -filter{banners-by-link}
6410 # Alias for specific file types that are text, but might have conflicting
6411 # MIME types. We want the browser to force these to be text documents.
6412 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>
6417 Say you have accounts on some sites that you visit regularly, and
6418 you don't want to have to log in manually each time. So you'd like
6419 to allow persistent cookies for these sites. The
6420 <literal>allow-all-cookies</literal> alias defined above does exactly
6421 that, i.e. it disables crunching of cookies in any direction, and the
6422 processing of cookies to make them only temporary.
6427 { allow-all-cookies }
6431 .redhat.com</screen>
6435 Your bank is allergic to some filter, but you don't know which, so you disable them all:
6440 { -<link linkend="FILTER">filter</link> }
6441 .your-home-banking-site.com</screen>
6445 Some file types you may not want to filter for various reasons:
6450 # Technical documentation is likely to contain strings that might
6451 # erroneously get altered by the JavaScript-oriented filters:
6456 # And this stupid host sends streaming video with a wrong MIME type,
6457 # so that Privoxy thinks it is getting HTML and starts filtering:
6459 stupid-server.example.com/</screen>
6463 Example of a simple <link linkend="BLOCK">block</link> action. Say you've
6464 seen an ad on your favourite page on example.com that you want to get rid of.
6465 You have right-clicked the image, selected <quote>copy image location</quote>
6466 and pasted the URL below while removing the leading http://, into a
6467 <literal>{ +block{} }</literal> section. Note that <literal>{ +handle-as-image
6468 }</literal> need not be specified, since all URLs ending in
6469 <literal>.gif</literal> will be tagged as images by the general rules as set
6470 in default.action anyway:
6475 { +<link linkend="BLOCK">block</link>{Nasty ads.} }
6476 www.example.com/nasty-ads/sponsor\.gif
6477 another.example.net/more/junk/here/</screen>
6481 The URLs of dynamically generated banners, especially from large banner
6482 farms, often don't use the well-known image file name extensions, which
6483 makes it impossible for <application>Privoxy</application> to guess
6484 the file type just by looking at the URL.
6485 You can use the <literal>+block-as-image</literal> alias defined above for
6487 Note that objects which match this rule but then turn out NOT to be an
6488 image are typically rendered as a <quote>broken image</quote> icon by the
6489 browser. Use cautiously.
6498 ar.atwola.com/</screen>
6502 Now you noticed that the default configuration breaks Forbes Magazine,
6503 but you were too lazy to find out which action is the culprit, and you
6504 were again too lazy to give <link linkend="contact">feedback</link>, so
6505 you just used the <literal>fragile</literal> alias on the site, and
6506 -- <emphasis>whoa!</emphasis> -- it worked. The <literal>fragile</literal>
6507 aliases disables those actions that are most likely to break a site. Also,
6508 good for testing purposes to see if it is <application>Privoxy</application>
6509 that is causing the problem or not. We later find other regular sites
6510 that misbehave, and add those to our personalized list of troublemakers:
6518 .mybank.com</screen>
6522 You like the <quote>fun</quote> text replacements in <filename>default.filter</filename>,
6523 but it is disabled in the distributed actions file.
6524 So you'd like to turn it on in your private,
6525 update-safe config, once and for all:
6530 { +<link linkend="filter-fun">filter{fun}</link> }
6531 / # For ALL sites!</screen>
6535 Note that the above is not really a good idea: There are exceptions
6536 to the filters in <filename>default.action</filename> for things that
6537 really shouldn't be filtered, like code on CVS->Web interfaces. Since
6538 <filename>user.action</filename> has the last word, these exceptions
6539 won't be valid for the <quote>fun</quote> filtering specified here.
6543 You might also worry about how your favourite free websites are
6544 funded, and find that they rely on displaying banner advertisements
6545 to survive. So you might want to specifically allow banners for those
6546 sites that you feel provide value to you:
6558 Note that <literal>allow-ads</literal> has been aliased to
6559 <literal>-<link linkend="block">block</link></literal>,
6560 <literal>-<link linkend="filter-banners-by-size">filter{banners-by-size}</link></literal>, and
6561 <literal>-<link linkend="filter-banners-by-link">filter{banners-by-link}</link></literal> above.
6565 Invoke another alias here to force an over-ride of the MIME type <literal>
6566 application/x-sh</literal> which typically would open a download type
6567 dialog. In my case, I want to look at the shell script, and then I can save
6568 it should I choose to.
6578 <filename>user.action</filename> is generally the best place to define
6579 exceptions and additions to the default policies of
6580 <filename>default.action</filename>. Some actions are safe to have their
6581 default policies set here though. So let's set a default policy to have a
6582 <quote>blank</quote> image as opposed to the checkerboard pattern for
6583 <emphasis>ALL</emphasis> sites. <quote>/</quote> of course matches all URL
6589 { +<link linkend="set-image-blocker">set-image-blocker{blank}</link> }
6590 / # ALL sites</screen>
6596 <!-- ~ End section ~ -->
6600 <!-- ~ End section ~ -->
6602 <!-- ~~~~~~~~ New section Header ~~~~~~~~~ -->
6604 <sect1 id="filter-file">
6605 <title>Filter Files</title>
6608 On-the-fly text substitutions need
6609 to be defined in a <quote>filter file</quote>. Once defined, they
6610 can then be invoked as an <quote>action</quote>.
6614 &my-app; supports three different pcrs-based filter actions:
6615 <literal><link linkend="filter">filter</link></literal> to
6616 rewrite the content that is send to the client,
6617 <literal><link linkend="client-header-filter">client-header-filter</link></literal>
6618 to rewrite headers that are send by the client, and
6619 <literal><link linkend="server-header-filter">server-header-filter</link></literal>
6620 to rewrite headers that are send by the server.
6624 &my-app; also supports two tagger actions:
6625 <literal><link linkend="client-header-tagger">client-header-tagger</link></literal>
6627 <literal><link linkend="server-header-tagger">server-header-tagger</link></literal>.
6628 Taggers and filters use the same syntax in the filter files, the difference
6629 is that taggers don't modify the text they are filtering, but use a rewritten
6630 version of the filtered text as tag. The tags can then be used to change the
6631 applying actions through sections with <link linkend="tag-pattern">tag-patterns</link>.
6635 Finally &my-app; supports the
6636 <literal><link linkend="external-filter">external-filter</link></literal> action
6637 to enable <literal><link linkend="external-filter-syntax">external filters</link></literal>
6638 written in proper programming languages.
6643 Multiple filter files can be defined through the <literal> <link
6644 linkend="filterfile">filterfile</link></literal> config directive. The filters
6645 as supplied by the developers are located in
6646 <filename>default.filter</filename>. It is recommended that any locally
6647 defined or modified filters go in a separately defined file such as
6648 <filename>user.filter</filename>.
6652 Common tasks for content filters are to eliminate common annoyances in
6653 HTML and JavaScript, such as pop-up windows,
6654 exit consoles, crippled windows without navigation tools, the
6655 infamous <BLINK> tag etc, to suppress images with certain
6656 width and height attributes (standard banner sizes or web-bugs),
6657 or just to have fun.
6661 Enabled content filters are applied to any content whose
6662 <quote>Content Type</quote> header is recognised as a sign
6663 of text-based content, with the exception of <literal>text/plain</literal>.
6664 Use the <link linkend="FORCE-TEXT-MODE">force-text-mode</link> action
6665 to also filter other content.
6669 Substitutions are made at the source level, so if you want to <quote>roll
6670 your own</quote> filters, you should first be familiar with HTML syntax,
6671 and, of course, regular expressions.
6675 Just like the <link linkend="actions-file">actions files</link>, the
6676 filter file is organized in sections, which are called <emphasis>filters</emphasis>
6677 here. Each filter consists of a heading line, that starts with one of the
6678 <emphasis>keywords</emphasis> <literal>FILTER:</literal>,
6679 <literal>CLIENT-HEADER-FILTER:</literal> or <literal>SERVER-HEADER-FILTER:</literal>
6680 followed by the filter's <emphasis>name</emphasis>, and a short (one line)
6681 <emphasis>description</emphasis> of what it does. Below that line
6682 come the <emphasis>jobs</emphasis>, i.e. lines that define the actual
6683 text substitutions. By convention, the name of a filter
6684 should describe what the filter <emphasis>eliminates</emphasis>. The
6685 comment is used in the <ulink url="http://config.privoxy.org/">web-based
6686 user interface</ulink>.
6690 Once a filter called <replaceable>name</replaceable> has been defined
6691 in the filter file, it can be invoked by using an action of the form
6692 +<literal><link linkend="filter">filter</link>{<replaceable>name</replaceable>}</literal>
6693 in any <link linkend="actions-file">actions file</link>.
6697 Filter definitions start with a header line that contains the filter
6698 type, the filter name and the filter description.
6699 A content filter header line for a filter called <quote>foo</quote> could look
6704 <screen>FILTER: foo Replace all "foo" with "bar"</screen>
6708 Below that line, and up to the next header line, come the jobs that
6709 define what text replacements the filter executes. They are specified
6710 in a syntax that imitates <ulink url="http://www.perl.org/">Perl</ulink>'s
6711 <literal>s///</literal> operator. If you are familiar with Perl, you
6712 will find this to be quite intuitive, and may want to look at the
6713 PCRS documentation for the subtle differences to Perl behaviour.
6717 Most notably, the non-standard option letter <literal>U</literal> is supported,
6718 which turns the default to ungreedy matching (add <literal>?</literal> to
6719 quantifiers to turn them greedy again).
6723 The non-standard option letter <literal>D</literal> (dynamic) allows
6724 to use the variables $host, $origin (the IP address the request came from),
6725 $path and $url. They will be replaced with the value they refer to before
6726 the filter is executed.
6730 Note that '$' is a bad choice for a delimiter in a dynamic filter as you
6731 might end up with unintended variables if you use a variable name
6732 directly after the delimiter. Variables will be resolved without
6733 escaping anything, therefore you also have to be careful not to chose
6734 delimiters that appear in the replacement text. For example '<' should
6735 be save, while '?' will sooner or later cause conflicts with $url.
6739 The non-standard option letter <literal>T</literal> (trivial) prevents
6740 parsing for backreferences in the substitute. Use it if you want to include
6741 text like '$&' in your substitute without quoting.
6746 <ulink url="http://en.wikipedia.org/wiki/Regular_expressions"><quote>Regular
6747 Expressions</quote></ulink>, you might want to take a look at
6748 the <link linkend="regex">Appendix on regular expressions</link>, and
6749 see the <ulink url="http://perldoc.perl.org/perlre.html">Perl
6751 <ulink url="http://perldoc.perl.org/perlop.html">the
6752 <literal>s///</literal> operator's syntax</ulink> and <ulink
6753 url="http://perldoc.perl.org/perlre.html">Perl-style regular
6754 expressions</ulink> in general.
6755 The below examples might also help to get you started.
6759 <!-- ~~~~~~~~ New section Header ~~~~~~~~~ -->
6761 <sect2><title>Filter File Tutorial</title>
6763 Now, let's complete our <quote>foo</quote> content filter. We have already defined
6764 the heading, but the jobs are still missing. Since all it does is to replace
6765 <quote>foo</quote> with <quote>bar</quote>, there is only one (trivial) job
6770 <screen>s/foo/bar/</screen>
6774 But wait! Didn't the comment say that <emphasis>all</emphasis> occurrences
6775 of <quote>foo</quote> should be replaced? Our current job will only take
6776 care of the first <quote>foo</quote> on each page. For global substitution,
6777 we'll need to add the <literal>g</literal> option:
6781 <screen>s/foo/bar/g</screen>
6785 Our complete filter now looks like this:
6788 <screen>FILTER: foo Replace all "foo" with "bar"
6789 s/foo/bar/g</screen>
6793 Let's look at some real filters for more interesting examples. Here you see
6794 a filter that protects against some common annoyances that arise from JavaScript
6795 abuse. Let's look at its jobs one after the other:
6801 FILTER: js-annoyances Get rid of particularly annoying JavaScript abuse
6803 # Get rid of JavaScript referrer tracking. Test page: http://www.randomoddness.com/untitled.htm
6805 s|(<script.*)document\.referrer(.*</script>)|$1"Not Your Business!"$2|Usg</screen>
6809 Following the header line and a comment, you see the job. Note that it uses
6810 <literal>|</literal> as the delimiter instead of <literal>/</literal>, because
6811 the pattern contains a forward slash, which would otherwise have to be escaped
6812 by a backslash (<literal>\</literal>).
6816 Now, let's examine the pattern: it starts with the text <literal><script.*</literal>
6817 enclosed in parentheses. Since the dot matches any character, and <literal>*</literal>
6818 means: <quote>Match an arbitrary number of the element left of myself</quote>, this
6819 matches <quote><script</quote>, followed by <emphasis>any</emphasis> text, i.e.
6820 it matches the whole page, from the start of the first <script> tag.
6824 That's more than we want, but the pattern continues: <literal>document\.referrer</literal>
6825 matches only the exact string <quote>document.referrer</quote>. The dot needed to
6826 be <emphasis>escaped</emphasis>, i.e. preceded by a backslash, to take away its
6827 special meaning as a joker, and make it just a regular dot. So far, the meaning is:
6828 Match from the start of the first <script> tag in a the page, up to, and including,
6829 the text <quote>document.referrer</quote>, if <emphasis>both</emphasis> are present
6830 in the page (and appear in that order).
6834 But there's still more pattern to go. The next element, again enclosed in parentheses,
6835 is <literal>.*</script></literal>. You already know what <literal>.*</literal>
6836 means, so the whole pattern translates to: Match from the start of the first <script>
6837 tag in a page to the end of the last <script> tag, provided that the text
6838 <quote>document.referrer</quote> appears somewhere in between.
6842 This is still not the whole story, since we have ignored the options and the parentheses:
6843 The portions of the page matched by sub-patterns that are enclosed in parentheses, will be
6844 remembered and be available through the variables <literal>$1, $2, ...</literal> in
6845 the substitute. The <literal>U</literal> option switches to ungreedy matching, which means
6846 that the first <literal>.*</literal> in the pattern will only <quote>eat up</quote> all
6847 text in between <quote><script</quote> and the <emphasis>first</emphasis> occurrence
6848 of <quote>document.referrer</quote>, and that the second <literal>.*</literal> will
6849 only span the text up to the <emphasis>first</emphasis> <quote></script></quote>
6850 tag. Furthermore, the <literal>s</literal> option says that the match may span
6851 multiple lines in the page, and the <literal>g</literal> option again means that the
6852 substitution is global.
6856 So, to summarize, the pattern means: Match all scripts that contain the text
6857 <quote>document.referrer</quote>. Remember the parts of the script from
6858 (and including) the start tag up to (and excluding) the string
6859 <quote>document.referrer</quote> as <literal>$1</literal>, and the part following
6860 that string, up to and including the closing tag, as <literal>$2</literal>.
6864 Now the pattern is deciphered, but wasn't this about substituting things? So
6865 lets look at the substitute: <literal>$1"Not Your Business!"$2</literal> is
6866 easy to read: The text remembered as <literal>$1</literal>, followed by
6867 <literal>"Not Your Business!"</literal> (<emphasis>including</emphasis>
6868 the quotation marks!), followed by the text remembered as <literal>$2</literal>.
6869 This produces an exact copy of the original string, with the middle part
6870 (the <quote>document.referrer</quote>) replaced by <literal>"Not Your
6871 Business!"</literal>.
6875 The whole job now reads: Replace <quote>document.referrer</quote> by
6876 <literal>"Not Your Business!"</literal> wherever it appears inside a
6877 <script> tag. Note that this job won't break JavaScript syntax,
6878 since both the original and the replacement are syntactically valid
6879 string objects. The script just won't have access to the referrer
6880 information anymore.
6884 We'll show you two other jobs from the JavaScript taming department, but
6885 this time only point out the constructs of special interest:
6890 # The status bar is for displaying link targets, not pointless blahblah
6892 s/window\.status\s*=\s*(['"]).*?\1/dUmMy=1/ig</screen>
6896 <literal>\s</literal> stands for whitespace characters (space, tab, newline,
6897 carriage return, form feed), so that <literal>\s*</literal> means: <quote>zero
6898 or more whitespace</quote>. The <literal>?</literal> in <literal>.*?</literal>
6899 makes this matching of arbitrary text ungreedy. (Note that the <literal>U</literal>
6900 option is not set). The <literal>['"]</literal> construct means: <quote>a single
6901 <emphasis>or</emphasis> a double quote</quote>. Finally, <literal>\1</literal> is
6902 a back-reference to the first parenthesis just like <literal>$1</literal> above,
6903 with the difference that in the <emphasis>pattern</emphasis>, a backslash indicates
6904 a back-reference, whereas in the <emphasis>substitute</emphasis>, it's the dollar.
6908 So what does this job do? It replaces assignments of single- or double-quoted
6909 strings to the <quote>window.status</quote> object with a dummy assignment
6910 (using a variable name that is hopefully odd enough not to conflict with
6911 real variables in scripts). Thus, it catches many cases where e.g. pointless
6912 descriptions are displayed in the status bar instead of the link target when
6913 you move your mouse over links.
6918 # Kill OnUnload popups. Yummy. Test: http://www.zdnet.com/zdsubs/yahoo/tree/yfs.html
6920 s/(<body [^>]*)onunload(.*>)/$1never$2/iU</screen>
6925 <ulink url="http://www.w3.org/TR/2000/REC-DOM-Level-2-Events-20001113/events.html#Events-eventgroupings-htmlevents">OnUnload
6926 event binding</ulink> in the HTML DOM was a <emphasis>CRIME</emphasis>.
6927 When I close a browser window, I want it to close and die. Basta.
6928 This job replaces the <quote>onunload</quote> attribute in
6929 <quote><body></quote> tags with the dummy word <literal>never</literal>.
6930 Note that the <literal>i</literal> option makes the pattern matching
6931 case-insensitive. Also note that ungreedy matching alone doesn't always guarantee
6932 a minimal match: In the first parenthesis, we had to use <literal>[^>]*</literal>
6933 instead of <literal>.*</literal> to prevent the match from exceeding the
6934 <body> tag if it doesn't contain <quote>OnUnload</quote>, but the page's
6939 The last example is from the fun department:
6944 FILTER: fun Fun text replacements
6946 # Spice the daily news:
6948 s/microsoft(?!\.com)/MicroSuck/ig</screen>
6952 Note the <literal>(?!\.com)</literal> part (a so-called negative lookahead)
6953 in the job's pattern, which means: Don't match, if the string
6954 <quote>.com</quote> appears directly following <quote>microsoft</quote>
6955 in the page. This prevents links to microsoft.com from being trashed, while
6956 still replacing the word everywhere else.
6961 # Buzzword Bingo (example for extended regex syntax)
6963 s* industry[ -]leading \
6965 | customer[ -]focused \
6966 | market[ -]driven \
6967 | award[ -]winning # Comments are OK, too! \
6968 | high[ -]performance \
6969 | solutions[ -]based \
6973 *<font color="red"><b>BINGO!</b></font> \
6978 The <literal>x</literal> option in this job turns on extended syntax, and allows for
6979 e.g. the liberal use of (non-interpreted!) whitespace for nicer formatting.
6987 <!-- ~~~~~~~~ New section Header ~~~~~~~~~ -->
6989 <sect2 id="predefined-filters"><title>The Pre-defined Filters</title>
6993 Note each filter is also listed in the +filter action section above. Please
6994 keep these listings in sync.
6999 The distribution <filename>default.filter</filename> file contains a selection of
7000 pre-defined filters for your convenience:
7005 <term><emphasis>js-annoyances</emphasis></term>
7008 The purpose of this filter is to get rid of particularly annoying JavaScript abuse.
7013 replaces JavaScript references to the browser's referrer information
7014 with the string "Not Your Business!". This compliments the <literal><link
7015 linkend="hide-referrer">hide-referrer</link></literal> action on the content level.
7020 removes the bindings to the DOM's
7021 <ulink url="http://www.w3.org/TR/2000/REC-DOM-Level-2-Events-20001113/events.html#Events-eventgroupings-htmlevents">unload
7022 event</ulink> which we feel has no right to exist and is responsible for most <quote>exit consoles</quote>, i.e.
7023 nasty windows that pop up when you close another one.
7028 removes code that causes new windows to be opened with undesired properties, such as being
7029 full-screen, non-resizeable, without location, status or menu bar etc.
7035 Use with caution. This is an aggressive filter, and can break sites that
7036 rely heavily on JavaScript.
7042 <term><emphasis>js-events</emphasis></term>
7045 This is a very radical measure. It removes virtually all JavaScript event bindings, which
7046 means that scripts can not react to user actions such as mouse movements or clicks, window
7047 resizing etc, anymore. Use with caution!
7050 We <emphasis>strongly discourage</emphasis> using this filter as a default since it breaks
7051 many legitimate scripts. It is meant for use only on extra-nasty sites (should you really
7058 <term><emphasis>html-annoyances</emphasis></term>
7061 This filter will undo many common instances of HTML based abuse.
7064 The <literal>BLINK</literal> and <literal>MARQUEE</literal> tags
7065 are neutralized (yeah baby!), and browser windows will be created as
7066 resizeable (as of course they should be!), and will have location,
7067 scroll and menu bars -- even if specified otherwise.
7073 <term><emphasis>content-cookies</emphasis></term>
7076 Most cookies are set in the HTTP dialog, where they can be intercepted
7078 <literal><link linkend="crunch-incoming-cookies">crunch-incoming-cookies</link></literal>
7079 and <literal><link linkend="crunch-outgoing-cookies">crunch-outgoing-cookies</link></literal>
7080 actions. But web sites increasingly make use of HTML meta tags and JavaScript
7081 to sneak cookies to the browser on the content level.
7084 This filter disables most HTML and JavaScript code that reads or sets
7085 cookies. It cannot detect all clever uses of these types of code, so it
7086 should not be relied on as an absolute fix. Use it wherever you would also
7087 use the cookie crunch actions.
7093 <term><emphasis>refresh-tags</emphasis></term>
7096 Disable any refresh tags if the interval is greater than nine seconds (so
7097 that redirections done via refresh tags are not destroyed). This is useful
7098 for dial-on-demand setups, or for those who find this HTML feature
7105 <term><emphasis>unsolicited-popups</emphasis></term>
7108 This filter attempts to prevent only <quote>unsolicited</quote> pop-up
7109 windows from opening, yet still allow pop-up windows that the user
7110 has explicitly chosen to open. It was added in version 3.0.1,
7111 as an improvement over earlier such filters.
7114 Technical note: The filter works by redefining the window.open JavaScript
7115 function to a dummy function, <literal>PrivoxyWindowOpen()</literal>,
7116 during the loading and rendering phase of each HTML page access, and
7117 restoring the function afterward.
7120 This is recommended only for browsers that cannot perform this function
7121 reliably themselves. And be aware that some sites require such windows
7122 in order to function normally. Use with caution.
7128 <term><emphasis>all-popups</emphasis></term>
7131 Attempt to prevent <emphasis>all</emphasis> pop-up windows from opening.
7132 Note this should be used with even more discretion than the above, since
7133 it is more likely to break some sites that require pop-ups for normal
7134 usage. Use with caution.
7140 <term><emphasis>img-reorder</emphasis></term>
7143 This is a helper filter that has no value if used alone. It makes the
7144 <literal>banners-by-size</literal> and <literal>banners-by-link</literal>
7145 (see below) filters more effective and should be enabled together with them.
7151 <term><emphasis>banners-by-size</emphasis></term>
7154 This filter removes image tags purely based on what size they are. Fortunately
7155 for us, many ads and banner images tend to conform to certain standardized
7156 sizes, which makes this filter quite effective for ad stripping purposes.
7159 Occasionally this filter will cause false positives on images that are not ads,
7160 but just happen to be of one of the standard banner sizes.
7163 Recommended only for those who require extreme ad blocking. The default
7164 block rules should catch 95+% of all ads <emphasis>without</emphasis> this filter enabled.
7170 <term><emphasis>banners-by-link</emphasis></term>
7173 This is an experimental filter that attempts to kill any banners if
7174 their URLs seem to point to known or suspected click trackers. It is currently
7175 not of much value and is not recommended for use by default.
7181 <term><emphasis>webbugs</emphasis></term>
7184 Webbugs are small, invisible images (technically 1X1 GIF images), that
7185 are used to track users across websites, and collect information on them.
7186 As an HTML page is loaded by the browser, an embedded image tag causes the
7187 browser to contact a third-party site, disclosing the tracking information
7188 through the requested URL and/or cookies for that third-party domain, without
7189 the user ever becoming aware of the interaction with the third-party site.
7190 HTML-ized spam also uses a similar technique to verify email addresses.
7193 This filter removes the HTML code that loads such <quote>webbugs</quote>.
7199 <term><emphasis>tiny-textforms</emphasis></term>
7202 A rather special-purpose filter that can be used to enlarge textareas (those
7203 multi-line text boxes in web forms) and turn off hard word wrap in them.
7204 It was written for the sourceforge.net tracker system where such boxes are
7205 a nuisance, but it can be handy on other sites, too.
7208 It is not recommended to use this filter as a default.
7214 <term><emphasis>jumping-windows</emphasis></term>
7217 Many consider windows that move, or resize themselves to be abusive. This filter
7218 neutralizes the related JavaScript code. Note that some sites might not display
7219 or behave as intended when using this filter. Use with caution.
7225 <term><emphasis>frameset-borders</emphasis></term>
7228 Some web designers seem to assume that everyone in the world will view their
7229 web sites using the same browser brand and version, screen resolution etc,
7230 because only that assumption could explain why they'd use static frame sizes,
7231 yet prevent their frames from being resized by the user, should they be too
7232 small to show their whole content.
7235 This filter removes the related HTML code. It should only be applied to sites
7242 <term><emphasis>demoronizer</emphasis></term>
7245 Many Microsoft products that generate HTML use non-standard extensions (read:
7246 violations) of the ISO 8859-1 aka Latin-1 character set. This can cause those
7247 HTML documents to display with errors on standard-compliant platforms.
7250 This filter translates the MS-only characters into Latin-1 equivalents.
7251 It is not necessary when using MS products, and will cause corruption of
7252 all documents that use 8-bit character sets other than Latin-1. It's mostly
7253 worthwhile for Europeans on non-MS platforms, if weird garbage characters
7254 sometimes appear on some pages, or user agents that don't correct for this on
7257 My version of Mozilla (ancient) shows litte square boxes for quote
7258 characters, and apostrophes on moronized pages. So many pages have this, I
7259 can read them fine now. HB 08/27/06
7266 <term><emphasis>shockwave-flash</emphasis></term>
7269 A filter for shockwave haters. As the name suggests, this filter strips code
7270 out of web pages that is used to embed shockwave flash objects.
7278 <term><emphasis>quicktime-kioskmode</emphasis></term>
7281 Change HTML code that embeds Quicktime objects so that kioskmode, which
7282 prevents saving, is disabled.
7288 <term><emphasis>fun</emphasis></term>
7291 Text replacements for subversive browsing fun. Make fun of your favorite
7292 Monopolist or play buzzword bingo.
7298 <term><emphasis>crude-parental</emphasis></term>
7301 A demonstration-only filter that shows how <application>Privoxy</application>
7302 can be used to delete web content on a keyword basis.
7308 <term><emphasis>ie-exploits</emphasis></term>
7311 An experimental collection of text replacements to disable malicious HTML and JavaScript
7312 code that exploits known security holes in Internet Explorer.
7315 Presently, it only protects against Nimda and a cross-site scripting bug, and
7316 would need active maintenance to provide more substantial protection.
7322 <term><emphasis>site-specifics</emphasis></term>
7325 Some web sites have very specific problems, the cure for which doesn't apply
7326 anywhere else, or could even cause damage on other sites.
7329 This is a collection of such site-specific cures which should only be applied
7330 to the sites they were intended for, which is what the supplied
7331 <filename>default.action</filename> file does. Users shouldn't need to change
7332 anything regarding this filter.
7338 <term><emphasis>google</emphasis></term>
7341 A CSS based block for Google text ads. Also removes a width limitation
7342 and the toolbar advertisement.
7348 <term><emphasis>yahoo</emphasis></term>
7351 Another CSS based block, this time for Yahoo text ads. And removes
7352 a width limitation as well.
7358 <term><emphasis>msn</emphasis></term>
7361 Another CSS based block, this time for MSN text ads. And removes
7362 tracking URLs, as well as a width limitation.
7368 <term><emphasis>blogspot</emphasis></term>
7371 Cleans up some Blogspot blogs. Read the fine print before using this one!
7374 This filter also intentionally removes some navigation stuff and sets the
7375 page width to 100%. As a result, some rounded <quote>corners</quote> would
7376 appear to early or not at all and as fixing this would require a browser
7377 that understands background-size (CSS3), they are removed instead.
7383 <term><emphasis>xml-to-html</emphasis></term>
7386 Server-header filter to change the Content-Type from xml to html.
7392 <term><emphasis>html-to-xml</emphasis></term>
7395 Server-header filter to change the Content-Type from html to xml.
7401 <term><emphasis>no-ping</emphasis></term>
7404 Removes the non-standard <literal>ping</literal> attribute from
7405 anchor and area HTML tags.
7411 <term><emphasis>hide-tor-exit-notation</emphasis></term>
7414 Client-header filter to remove the <command>Tor</command> exit node notation
7415 found in Host and Referer headers.
7418 If &my-app; and <command>Tor</command> are chained and &my-app;
7419 is configured to use socks4a, one can use <quote>http://www.example.org.foobar.exit/</quote>
7420 to access the host <quote>www.example.org</quote> through the
7421 <command>Tor</command> exit node <quote>foobar</quote>.
7424 As the HTTP client isn't aware of this notation, it treats the
7425 whole string <quote>www.example.org.foobar.exit</quote> as host and uses it
7426 for the <quote>Host</quote> and <quote>Referer</quote> headers. From the
7427 server's point of view the resulting headers are invalid and can cause problems.
7430 An invalid <quote>Referer</quote> header can trigger <quote>hot-linking</quote>
7431 protections, an invalid <quote>Host</quote> header will make it impossible for
7432 the server to find the right vhost (several domains hosted on the same IP address).
7435 This client-header filter removes the <quote>foo.exit</quote> part in those headers
7436 to prevent the mentioned problems. Note that it only modifies
7437 the HTTP headers, it doesn't make it impossible for the server
7438 to detect your <command>Tor</command> exit node based on the IP address
7439 the request is coming from.
7446 <term><emphasis> </emphasis></term>
7459 <!-- ~~~~~~~~ New section Header ~~~~~~~~~ -->
7460 <sect2 id="external-filter-syntax"><title>External filter syntax</title>
7462 External filters are scripts or programs that can modify the content in
7463 case common <literal><link linkend="filter">filters</link></literal>
7464 aren't powerful enough.
7467 External filters can be written in any language the platform &my-app; runs
7471 They are controlled with the
7472 <literal><link linkend="external-filter">external-filter</link></literal> action
7473 and have to be defined in the <literal><link linkend="filterfile">filterfile</link></literal>
7477 The header looks like any other filter, but instead of pcrs jobs, external
7478 filters contain a single job which can be a program or a shell script (which
7479 may call other scripts or programs).
7482 External filters read the content from STDIN and write the rewritten
7483 content to STDOUT. The environment variables PRIVOXY_URL, PRIVOXY_PATH,
7484 PRIVOXY_HOST, PRIVOXY_ORIGIN can be used to get some details about the
7488 &my-app; will temporary store the content to filter in the
7489 <literal><link linkend="temporary-directory">temporary-directory</link></literal>.
7493 EXTERNAL-FILTER: cat Pointless example filter that doesn't actually modify the content
7496 # Incorrect reimplementation of the filter above in POSIX shell.
7498 # Note that it's a single job that spans multiple lines, the line
7499 # breaks are not passed to the shell, thus the semicolons are required.
7501 # If the script isn't trivial, it is recommended to put it into an external file.
7503 # In general, writing external filters entirely in POSIX shell is not
7504 # considered a good idea.
7505 EXTERNAL-FILTER: cat2 Pointless example filter that despite its name may actually modify the content
7511 EXTERNAL-FILTER: rotate-image Rotate an image by 180 degree. Test filter with limited value.
7512 /usr/local/bin/convert - -rotate 180 -
7514 EXTERNAL-FILTER: citation-needed Adds a "[citation needed]" tag to an image. The coordinates may need adjustment.
7515 /usr/local/bin/convert - -pointsize 16 -fill white -annotate +17+418 "[citation needed]" -
7521 Currently external filters are executed with &my-app;'s privileges!
7522 Only use external filters you understand and trust.
7526 External filters are experimental and the syntax may change in the future.
7532 <!-- ~ End section ~ -->
7536 <!-- ~~~~~ New section ~~~~~ -->
7538 <sect1 id="templates">
7539 <title>Privoxy's Template Files</title>
7541 All <application>Privoxy</application> built-in pages, i.e. error pages such as the
7542 <ulink url="http://show-the-404-error.page"><quote>404 - No Such Domain</quote>
7543 error page</ulink>, the <ulink
7544 url="http://ads.bannerserver.example.com/nasty-ads/sponsor.html"><quote>BLOCKED</quote>
7546 and all pages of its <ulink url="http://config.privoxy.org/">web-based
7547 user interface</ulink>, are generated from <emphasis>templates</emphasis>.
7548 (<application>Privoxy</application> must be running for the above links to work as
7553 These templates are stored in a subdirectory of the <link linkend="confdir">configuration
7554 directory</link> called <filename>templates</filename>. On Unixish platforms,
7556 <ulink url="file:///etc/privoxy/templates/"><filename>/etc/privoxy/templates/</filename></ulink>.
7560 The templates are basically normal HTML files, but with place-holders (called symbols
7561 or exports), which <application>Privoxy</application> fills at run time. It
7562 is possible to edit the templates with a normal text editor, should you want
7563 to customize them. (<emphasis>Not recommended for the casual
7564 user</emphasis>). Should you create your own custom templates, you should use
7565 the <filename>config</filename> setting <link linkend="templdir">templdir</link>
7566 to specify an alternate location, so your templates do not get overwritten
7570 Note that just like in configuration files, lines starting
7571 with <literal>#</literal> are ignored when the templates are filled in.
7575 The place-holders are of the form <literal>@name@</literal>, and you will
7576 find a list of available symbols, which vary from template to template,
7577 in the comments at the start of each file. Note that these comments are not
7578 always accurate, and that it's probably best to look at the existing HTML
7579 code to find out which symbols are supported and what they are filled in with.
7583 A special application of this substitution mechanism is to make whole
7584 blocks of HTML code disappear when a specific symbol is set. We use this
7585 for many purposes, one of them being to include the beta warning in all
7586 our user interface (CGI) pages when <application>Privoxy</application>
7587 is in an alpha or beta development stage:
7592 <!-- @if-unstable-start -->
7594 ... beta warning HTML code goes here ...
7596 <!-- if-unstable-end@ --></screen>
7600 If the "unstable" symbol is set, everything in between and including
7601 <literal>@if-unstable-start</literal> and <literal>if-unstable-end@</literal>
7602 will disappear, leaving nothing but an empty comment:
7606 <screen><!-- --></screen>
7610 There's also an if-then-else construct and an <literal>#include</literal>
7611 mechanism, but you'll sure find out if you are inclined to edit the
7616 All templates refer to a style located at
7617 <ulink url="http://config.privoxy.org/send-stylesheet"><literal>http://config.privoxy.org/send-stylesheet</literal></ulink>.
7618 This is, of course, locally served by <application>Privoxy</application>
7619 and the source for it can be found and edited in the
7620 <filename>cgi-style.css</filename> template.
7625 <!-- ~ End section ~ -->
7629 <!-- ~~~~~ New section ~~~~~ -->
7631 <sect1 id="contact"><title>Contacting the Developers, Bug Reporting and Feature
7634 <!-- Include contacting.sgml boilerplate: -->
7636 <!-- end boilerplate -->
7640 <!-- ~ End section ~ -->
7643 <!-- ~~~~~ New section ~~~~~ -->
7644 <sect1 id="copyright"><title>Privoxy Copyright, License and History</title>
7646 <!-- Include copyright.sgml: -->
7648 <!-- end copyright -->
7651 <application>Privoxy</application> is free software; you can
7652 redistribute it and/or modify it under the terms of the
7653 <citetitle>GNU General Public License</citetitle>, version 2,
7654 as published by the Free Software Foundation and included in
7658 <!-- ~~~~~ New section ~~~~~ -->
7659 <sect2 id="license"><title>License</title>
7661 <screen><![ RCDATA [ &GPLv2; ]]></screen>
7665 <!-- ~ End section ~ -->
7668 <!-- ~~~~~ New section ~~~~~ -->
7670 <sect2 id="history"><title>History</title>
7671 <!-- Include history.sgml: -->
7673 <!-- end history -->
7676 <sect2 id="authors"><title>Authors</title>
7677 <!-- Include p-authors.sgml: -->
7679 <!-- end authors -->
7684 <!-- ~ End section ~ -->
7687 <!-- ~~~~~ New section ~~~~~ -->
7688 <sect1 id="seealso"><title>See Also</title>
7689 <!-- Include seealso.sgml: -->
7691 <!-- end seealso -->
7696 <!-- ~~~~~ New section ~~~~~ -->
7697 <sect1 id="appendix"><title>Appendix</title>
7700 <!-- ~~~~~ New section ~~~~~ -->
7702 <title>Regular Expressions</title>
7704 <application>Privoxy</application> uses Perl-style <quote>regular
7705 expressions</quote> in its <link linkend="actions-file">actions
7706 files</link> and <link linkend="filter-file">filter file</link>,
7707 through the <ulink url="http://www.pcre.org/">PCRE</ulink> and
7710 <ulink url="http://www.oesterhelt.org/pcrs/">PCRS</ulink> libraries.
7712 <application>PCRS</application> libraries.
7716 If you are reading this, you probably don't understand what <quote>regular
7717 expressions</quote> are, or what they can do. So this will be a very brief
7718 introduction only. A full explanation would require a <ulink
7719 url="http://www.oreilly.com/catalog/regex/">book</ulink> ;-)
7723 Regular expressions provide a language to describe patterns that can be
7724 run against strings of characters (letter, numbers, etc), to see if they
7725 match the string or not. The patterns are themselves (sometimes complex)
7726 strings of literal characters, combined with wild-cards, and other special
7727 characters, called meta-characters. The <quote>meta-characters</quote> have
7728 special meanings and are used to build complex patterns to be matched against.
7729 Perl Compatible Regular Expressions are an especially convenient
7730 <quote>dialect</quote> of the regular expression language.
7734 To make a simple analogy, we do something similar when we use wild-card
7735 characters when listing files with the <command>dir</command> command in DOS.
7736 <literal>*.*</literal> matches all filenames. The <quote>special</quote>
7737 character here is the asterisk which matches any and all characters. We can be
7738 more specific and use <literal>?</literal> to match just individual
7739 characters. So <quote>dir file?.text</quote> would match
7740 <quote>file1.txt</quote>, <quote>file2.txt</quote>, etc. We are pattern
7741 matching, using a similar technique to <quote>regular expressions</quote>!
7745 Regular expressions do essentially the same thing, but are much, much more
7746 powerful. There are many more <quote>special characters</quote> and ways of
7747 building complex patterns however. Let's look at a few of the common ones,
7748 and then some examples:
7753 <emphasis>.</emphasis> - Matches any single character, e.g. <quote>a</quote>,
7754 <quote>A</quote>, <quote>4</quote>, <quote>:</quote>, or <quote>@</quote>.
7756 </simplelist></para>
7760 <emphasis>?</emphasis> - The preceding character or expression is matched ZERO or ONE
7763 </simplelist></para>
7767 <emphasis>+</emphasis> - The preceding character or expression is matched ONE or MORE
7770 </simplelist></para>
7774 <emphasis>*</emphasis> - The preceding character or expression is matched ZERO or MORE
7777 </simplelist></para>
7781 <emphasis>\</emphasis> - The <quote>escape</quote> character denotes that
7782 the following character should be taken literally. This is used where one of the
7783 special characters (e.g. <quote>.</quote>) needs to be taken literally and
7784 not as a special meta-character. Example: <quote>example\.com</quote>, makes
7785 sure the period is recognized only as a period (and not expanded to its
7786 meta-character meaning of any single character).
7788 </simplelist></para>
7792 <emphasis>[ ]</emphasis> - Characters enclosed in brackets will be matched if
7793 any of the enclosed characters are encountered. For instance, <quote>[0-9]</quote>
7794 matches any numeric digit (zero through nine). As an example, we can combine
7795 this with <quote>+</quote> to match any digit one of more times: <quote>[0-9]+</quote>.
7797 </simplelist></para>
7801 <emphasis>( )</emphasis> - parentheses are used to group a sub-expression,
7802 or multiple sub-expressions.
7804 </simplelist></para>
7808 <emphasis>|</emphasis> - The <quote>bar</quote> character works like an
7809 <quote>or</quote> conditional statement. A match is successful if the
7810 sub-expression on either side of <quote>|</quote> matches. As an example:
7811 <quote>/(this|that) example/</quote> uses grouping and the bar character
7812 and would match either <quote>this example</quote> or <quote>that
7813 example</quote>, and nothing else.
7815 </simplelist></para>
7818 These are just some of the ones you are likely to use when matching URLs with
7819 <application>Privoxy</application>, and is a long way from a definitive
7820 list. This is enough to get us started with a few simple examples which may
7821 be more illuminating:
7825 <emphasis><literal>/.*/banners/.*</literal></emphasis> - A simple example
7826 that uses the common combination of <quote>.</quote> and <quote>*</quote> to
7827 denote any character, zero or more times. In other words, any string at all.
7828 So we start with a literal forward slash, then our regular expression pattern
7829 (<quote>.*</quote>) another literal forward slash, the string
7830 <quote>banners</quote>, another forward slash, and lastly another
7831 <quote>.*</quote>. We are building
7832 a directory path here. This will match any file with the path that has a
7833 directory named <quote>banners</quote> in it. The <quote>.*</quote> matches
7834 any characters, and this could conceivably be more forward slashes, so it
7835 might expand into a much longer looking path. For example, this could match:
7836 <quote>/eye/hate/spammers/banners/annoy_me_please.gif</quote>, or just
7837 <quote>/banners/annoying.html</quote>, or almost an infinite number of other
7838 possible combinations, just so it has <quote>banners</quote> in the path
7843 And now something a little more complex:
7847 <emphasis><literal>/.*/adv((er)?ts?|ertis(ing|ements?))?/</literal></emphasis> -
7848 We have several literal forward slashes again (<quote>/</quote>), so we are
7849 building another expression that is a file path statement. We have another
7850 <quote>.*</quote>, so we are matching against any conceivable sub-path, just so
7851 it matches our expression. The only true literal that <emphasis>must
7852 match</emphasis> our pattern is <application>adv</application>, together with
7853 the forward slashes. What comes after the <quote>adv</quote> string is the
7858 Remember the <quote>?</quote> means the preceding expression (either a
7859 literal character or anything grouped with <quote>(...)</quote> in this case)
7860 can exist or not, since this means either zero or one match. So
7861 <quote>((er)?ts?|ertis(ing|ements?))</quote> is optional, as are the
7862 individual sub-expressions: <quote>(er)</quote>,
7863 <quote>(ing|ements?)</quote>, and the <quote>s</quote>. The <quote>|</quote>
7864 means <quote>or</quote>. We have two of those. For instance,
7865 <quote>(ing|ements?)</quote>, can expand to match either <quote>ing</quote>
7866 <emphasis>OR</emphasis> <quote>ements?</quote>. What is being done here, is an
7867 attempt at matching as many variations of <quote>advertisement</quote>, and
7868 similar, as possible. So this would expand to match just <quote>adv</quote>,
7869 or <quote>advert</quote>, or <quote>adverts</quote>, or
7870 <quote>advertising</quote>, or <quote>advertisement</quote>, or
7871 <quote>advertisements</quote>. You get the idea. But it would not match
7872 <quote>advertizements</quote> (with a <quote>z</quote>). We could fix that by
7873 changing our regular expression to:
7874 <quote>/.*/adv((er)?ts?|erti(s|z)(ing|ements?))?/</quote>, which would then match
7879 <emphasis><literal>/.*/advert[0-9]+\.(gif|jpe?g)</literal></emphasis> - Again
7880 another path statement with forward slashes. Anything in the square brackets
7881 <quote>[ ]</quote> can be matched. This is using <quote>0-9</quote> as a
7882 shorthand expression to mean any digit one through nine. It is the same as
7883 saying <quote>0123456789</quote>. So any digit matches. The <quote>+</quote>
7884 means one or more of the preceding expression must be included. The preceding
7885 expression here is what is in the square brackets -- in this case, any digit
7886 one through nine. Then, at the end, we have a grouping: <quote>(gif|jpe?g)</quote>.
7887 This includes a <quote>|</quote>, so this needs to match the expression on
7888 either side of that bar character also. A simple <quote>gif</quote> on one side, and the other
7889 side will in turn match either <quote>jpeg</quote> or <quote>jpg</quote>,
7890 since the <quote>?</quote> means the letter <quote>e</quote> is optional and
7891 can be matched once or not at all. So we are building an expression here to
7892 match image GIF or JPEG type image file. It must include the literal
7893 string <quote>advert</quote>, then one or more digits, and a <quote>.</quote>
7894 (which is now a literal, and not a special character, since it is escaped
7895 with <quote>\</quote>), and lastly either <quote>gif</quote>, or
7896 <quote>jpeg</quote>, or <quote>jpg</quote>. Some possible matches would
7897 include: <quote>//advert1.jpg</quote>,
7898 <quote>/nasty/ads/advert1234.gif</quote>,
7899 <quote>/banners/from/hell/advert99.jpg</quote>. It would not match
7900 <quote>advert1.gif</quote> (no leading slash), or
7901 <quote>/adverts232.jpg</quote> (the expression does not include an
7902 <quote>s</quote>), or <quote>/advert1.jsp</quote> (<quote>jsp</quote> is not
7903 in the expression anywhere).
7907 We are barely scratching the surface of regular expressions here so that you
7908 can understand the default <application>Privoxy</application>
7909 configuration files, and maybe use this knowledge to customize your own
7910 installation. There is much, much more that can be done with regular
7911 expressions. Now that you know enough to get started, you can learn more on
7916 More reading on Perl Compatible Regular expressions:
7917 <ulink url="http://perldoc.perl.org/perlre.html">http://perldoc.perl.org/perlre.html</ulink>
7921 For information on regular expression based substitutions and their applications
7922 in filters, please see the <link linkend="filter-file">filter file tutorial</link>
7927 <!-- ~ End section ~ -->
7930 <!-- ~~~~~ New section ~~~~~ -->
7932 <title>Privoxy's Internal Pages</title>
7935 Since <application>Privoxy</application> proxies each requested
7936 web page, it is easy for <application>Privoxy</application> to
7937 trap certain special URLs. In this way, we can talk directly to
7938 <application>Privoxy</application>, and see how it is
7939 configured, see how our rules are being applied, change these
7940 rules and other configuration options, and even turn
7941 <application>Privoxy's</application> filtering off, all with
7947 The URLs listed below are the special ones that allow direct access
7948 to <application>Privoxy</application>. Of course,
7949 <application>Privoxy</application> must be running to access these. If
7950 not, you will get a friendly error message. Internet access is not
7963 <ulink url="http://config.privoxy.org/">http://config.privoxy.org/</ulink>
7967 There is a shortcut: <ulink url="http://p.p/">http://p.p/</ulink> (But it
7968 doesn't provide a fall-back to a real page, in case the request is not
7969 sent through <application>Privoxy</application>)
7975 Show information about the current configuration, including viewing and
7976 editing of actions files:
7980 <ulink url="http://config.privoxy.org/show-status">http://config.privoxy.org/show-status</ulink>
7987 Show the source code version numbers:
7991 <ulink url="http://config.privoxy.org/show-version">http://config.privoxy.org/show-version</ulink>
7998 Show the browser's request headers:
8002 <ulink url="http://config.privoxy.org/show-request">http://config.privoxy.org/show-request</ulink>
8009 Show which actions apply to a URL and why:
8013 <ulink url="http://config.privoxy.org/show-url-info">http://config.privoxy.org/show-url-info</ulink>
8020 Toggle Privoxy on or off. This feature can be turned off/on in the main
8021 <filename>config</filename> file. When toggled <quote>off</quote>, <quote>Privoxy</quote>
8022 continues to run, but only as a pass-through proxy, with no actions taking
8027 <ulink url="http://config.privoxy.org/toggle">http://config.privoxy.org/toggle</ulink>
8031 Short cuts. Turn off, then on:
8035 <ulink url="http://config.privoxy.org/toggle?set=disable">http://config.privoxy.org/toggle?set=disable</ulink>
8040 <ulink url="http://config.privoxy.org/toggle?set=enable">http://config.privoxy.org/toggle?set=enable</ulink>
8051 <!-- ~~~~~ New section ~~~~~ -->
8053 <title>Chain of Events</title>
8055 Let's take a quick look at how some of <application>Privoxy's</application>
8056 core features are triggered, and the ensuing sequence of events when a web
8057 page is requested by your browser:
8064 First, your web browser requests a web page. The browser knows to send
8065 the request to <application>Privoxy</application>, which will in turn,
8066 relay the request to the remote web server after passing the following
8072 <application>Privoxy</application> traps any request for its own internal CGI
8073 pages (e.g <ulink url="http://p.p/">http://p.p/</ulink>) and sends the CGI page back to the browser.
8078 Next, <application>Privoxy</application> checks to see if the URL
8080 linkend="BLOCK"><quote>+block</quote></link> patterns. If
8081 so, the URL is then blocked, and the remote web server will not be contacted.
8082 <link linkend="HANDLE-AS-IMAGE"><quote>+handle-as-image</quote></link>
8084 <link linkend="HANDLE-AS-EMPTY-DOCUMENT"><quote>+handle-as-empty-document</quote></link>
8085 are then checked, and if there is no match, an
8086 HTML <quote>BLOCKED</quote> page is sent back to the browser. Otherwise, if
8087 it does match, an image is returned for the former, and an empty text
8088 document for the latter. The type of image would depend on the setting of
8089 <link linkend="SET-IMAGE-BLOCKER"><quote>+set-image-blocker</quote></link>
8090 (blank, checkerboard pattern, or an HTTP redirect to an image elsewhere).
8095 Untrusted URLs are blocked. If URLs are being added to the
8096 <filename>trust</filename> file, then that is done.
8101 If the URL pattern matches the <link
8102 linkend="FAST-REDIRECTS"><quote>+fast-redirects</quote></link> action,
8103 it is then processed. Unwanted parts of the requested URL are stripped.
8108 Now the rest of the client browser's request headers are processed. If any
8109 of these match any of the relevant actions (e.g. <link
8110 linkend="HIDE-USER-AGENT"><quote>+hide-user-agent</quote></link>,
8111 etc.), headers are suppressed or forged as determined by these actions and
8117 Now the web server starts sending its response back (i.e. typically a web
8123 First, the server headers are read and processed to determine, among other
8124 things, the MIME type (document type) and encoding. The headers are then
8125 filtered as determined by the
8126 <link linkend="CRUNCH-INCOMING-COOKIES"><quote>+crunch-incoming-cookies</quote></link>,
8127 <link linkend="SESSION-COOKIES-ONLY"><quote>+session-cookies-only</quote></link>,
8128 and <link linkend="DOWNGRADE-HTTP-VERSION"><quote>+downgrade-http-version</quote></link>
8134 If any <link linkend="FILTER"><quote>+filter</quote></link> action
8136 linkend="DEANIMATE-GIFS"><quote>+deanimate-gifs</quote></link>
8137 action applies (and the document type fits the action), the rest of the page is
8138 read into memory (up to a configurable limit). Then the filter rules (from
8139 <filename>default.filter</filename> and any other filter files) are
8140 processed against the buffered content. Filters are applied in the order
8141 they are specified in one of the filter files. Animated GIFs, if present,
8142 are reduced to either the first or last frame, depending on the action
8143 setting.The entire page, which is now filtered, is then sent by
8144 <application>Privoxy</application> back to your browser.
8147 If neither a <link linkend="FILTER"><quote>+filter</quote></link> action
8149 linkend="DEANIMATE-GIFS"><quote>+deanimate-gifs</quote></link>
8150 matches, then <application>Privoxy</application> passes the raw data through
8151 to the client browser as it becomes available.
8156 As the browser receives the now (possibly filtered) page content, it
8157 reads and then requests any URLs that may be embedded within the page
8158 source, e.g. ad images, stylesheets, JavaScript, other HTML documents (e.g.
8159 frames), sounds, etc. For each of these objects, the browser issues a
8160 separate request (this is easily viewable in <application>Privoxy's</application>
8161 logs). And each such request is in turn processed just as above. Note that a
8162 complex web page will have many, many such embedded URLs. If these
8163 secondary requests are to a different server, then quite possibly a very
8164 differing set of actions is triggered.
8171 NOTE: This is somewhat of a simplistic overview of what happens with each URL
8172 request. For the sake of brevity and simplicity, we have focused on
8173 <application>Privoxy's</application> core features only.
8179 <!-- ~~~~~ New section ~~~~~ -->
8180 <sect2 id="actionsanat">
8181 <title>Troubleshooting: Anatomy of an Action</title>
8184 The way <application>Privoxy</application> applies
8185 <link linkend="ACTIONS">actions</link> and <link linkend="FILTER">filters</link>
8186 to any given URL can be complex, and not always so
8187 easy to understand what is happening. And sometimes we need to be able to
8188 <emphasis>see</emphasis> just what <application>Privoxy</application> is
8189 doing. Especially, if something <application>Privoxy</application> is doing
8190 is causing us a problem inadvertently. It can be a little daunting to look at
8191 the actions and filters files themselves, since they tend to be filled with
8192 <link linkend="regex">regular expressions</link> whose consequences are not
8197 One quick test to see if <application>Privoxy</application> is causing a problem
8198 or not, is to disable it temporarily. This should be the first troubleshooting
8199 step (be sure to flush caches afterward!). Looking at the
8200 logs is a good idea too. (Note that both the toggle feature and logging are
8201 enabled via <filename>config</filename> file settings, and may need to be
8202 turned <quote>on</quote>.)
8205 Another easy troubleshooting step to try is if you have done any
8206 customization of your installation, revert back to the installed
8207 defaults and see if that helps. There are times the developers get complaints
8208 about one thing or another, and the problem is more related to a customized
8209 configuration issue.
8213 <application>Privoxy</application> also provides the
8214 <ulink url="http://config.privoxy.org/show-url-info">http://config.privoxy.org/show-url-info</ulink>
8215 page that can show us very specifically how <application>actions</application>
8216 are being applied to any given URL. This is a big help for troubleshooting.
8220 First, enter one URL (or partial URL) at the prompt, and then
8221 <application>Privoxy</application> will tell us
8222 how the current configuration will handle it. This will not
8223 help with filtering effects (i.e. the <link
8224 linkend="FILTER"><quote>+filter</quote></link> action) from
8225 one of the filter files since this is handled very
8226 differently and not so easy to trap! It also will not tell you about any other
8227 URLs that may be embedded within the URL you are testing. For instance, images
8228 such as ads are expressed as URLs within the raw page source of HTML pages. So
8229 you will only get info for the actual URL that is pasted into the prompt area
8230 -- not any sub-URLs. If you want to know about embedded URLs like ads, you
8231 will have to dig those out of the HTML source. Use your browser's <quote>View
8232 Page Source</quote> option for this. Or right click on the ad, and grab the
8237 Let's try an example, <ulink url="http://google.com">google.com</ulink>,
8238 and look at it one section at a time in a sample configuration (your real
8239 configuration may vary):
8244 Matches for http://www.google.com:
8246 In file: default.action <guibutton>[ View ]</guibutton> <guibutton>[ Edit ]</guibutton>
8248 {+change-x-forwarded-for{block}
8249 +deanimate-gifs {last}
8250 +fast-redirects {check-decoded-url}
8251 +filter {refresh-tags}
8252 +filter {img-reorder}
8253 +filter {banners-by-size}
8255 +filter {jumping-windows}
8256 +filter {ie-exploits}
8257 +hide-from-header {block}
8258 +hide-referrer {forge}
8259 +session-cookies-only
8260 +set-image-blocker {pattern}
8263 { -session-cookies-only }
8269 In file: user.action <guibutton>[ View ]</guibutton> <guibutton>[ Edit ]</guibutton>
8270 (no matches in this file)
8275 This is telling us how we have defined our
8276 <link linkend="ACTIONS"><quote>actions</quote></link>, and
8277 which ones match for our test case, <quote>google.com</quote>.
8278 Displayed is all the actions that are available to us. Remember,
8279 the <literal>+</literal> sign denotes <quote>on</quote>. <literal>-</literal>
8280 denotes <quote>off</quote>. So some are <quote>on</quote> here, but many
8281 are <quote>off</quote>. Each example we try may provide a slightly different
8282 end result, depending on our configuration directives.
8286 is for our <filename>default.action</filename> file. The large, multi-line
8287 listing, is how the actions are set to match for all URLs, i.e. our default
8288 settings. If you look at your <quote>actions</quote> file, this would be the
8289 section just below the <quote>aliases</quote> section near the top. This
8290 will apply to all URLs as signified by the single forward slash at the end
8291 of the listing -- <quote> / </quote>.
8295 But we have defined additional actions that would be exceptions to these general
8296 rules, and then we list specific URLs (or patterns) that these exceptions
8297 would apply to. Last match wins. Just below this then are two explicit
8298 matches for <quote>.google.com</quote>. The first is negating our previous
8299 cookie setting, which was for <link
8300 linkend="SESSION-COOKIES-ONLY"><quote>+session-cookies-only</quote></link>
8301 (i.e. not persistent). So we will allow persistent cookies for google, at
8302 least that is how it is in this example. The second turns
8303 <emphasis>off</emphasis> any <link
8304 linkend="FAST-REDIRECTS"><quote>+fast-redirects</quote></link>
8305 action, allowing this to take place unmolested. Note that there is a leading
8306 dot here -- <quote>.google.com</quote>. This will match any hosts and
8307 sub-domains, in the google.com domain also, such as
8308 <quote>www.google.com</quote> or <quote>mail.google.com</quote>. But it would not
8309 match <quote>www.google.de</quote>! So, apparently, we have these two actions
8310 defined as exceptions to the general rules at the top somewhere in the lower
8311 part of our <filename>default.action</filename> file, and
8312 <quote>google.com</quote> is referenced somewhere in these latter sections.
8316 Then, for our <filename>user.action</filename> file, we again have no hits.
8317 So there is nothing google-specific that we might have added to our own, local
8318 configuration. If there was, those actions would over-rule any actions from
8319 previously processed files, such as <filename>default.action</filename>.
8320 <filename>user.action</filename> typically has the last word. This is the
8321 best place to put hard and fast exceptions,
8325 And finally we pull it all together in the bottom section and summarize how
8326 <application>Privoxy</application> is applying all its <quote>actions</quote>
8327 to <quote>google.com</quote>:
8338 +change-x-forwarded-for{block}
8339 -client-header-filter{hide-tor-exit-notation}
8340 -content-type-overwrite
8341 -crunch-client-header
8342 -crunch-if-none-match
8343 -crunch-incoming-cookies
8344 -crunch-outgoing-cookies
8345 -crunch-server-header
8346 +deanimate-gifs {last}
8347 -downgrade-http-version
8350 -filter {content-cookies}
8351 -filter {all-popups}
8352 -filter {banners-by-link}
8353 -filter {tiny-textforms}
8354 -filter {frameset-borders}
8355 -filter {demoronizer}
8356 -filter {shockwave-flash}
8357 -filter {quicktime-kioskmode}
8359 -filter {crude-parental}
8360 -filter {site-specifics}
8361 -filter {js-annoyances}
8362 -filter {html-annoyances}
8363 +filter {refresh-tags}
8364 -filter {unsolicited-popups}
8365 +filter {img-reorder}
8366 +filter {banners-by-size}
8368 +filter {jumping-windows}
8369 +filter {ie-exploits}
8376 -handle-as-empty-document
8378 -hide-accept-language
8379 -hide-content-disposition
8380 +hide-from-header {block}
8381 -hide-if-modified-since
8382 +hide-referrer {forge}
8385 -overwrite-last-modified
8386 -prevent-compression
8388 -server-header-filter{xml-to-html}
8389 -server-header-filter{html-to-xml}
8390 -session-cookies-only
8391 +set-image-blocker {pattern} </screen>
8395 Notice the only difference here to the previous listing, is to
8396 <quote>fast-redirects</quote> and <quote>session-cookies-only</quote>,
8397 which are activated specifically for this site in our configuration,
8398 and thus show in the <quote>Final Results</quote>.
8402 Now another example, <quote>ad.doubleclick.net</quote>:
8408 { +block{Domains starts with "ad"} }
8411 { +block{Domain contains "ad"} }
8414 { +block{Doubleclick banner server} +handle-as-image }
8415 .[a-vx-z]*.doubleclick.net
8420 We'll just show the interesting part here - the explicit matches. It is
8421 matched three different times. Two <quote>+block{}</quote> sections,
8422 and a <quote>+block{} +handle-as-image</quote>,
8423 which is the expanded form of one of our aliases that had been defined as:
8424 <quote>+block-as-image</quote>. (<link
8425 linkend="ALIASES"><quote>Aliases</quote></link> are defined in
8426 the first section of the actions file and typically used to combine more
8431 Any one of these would have done the trick and blocked this as an unwanted
8432 image. This is unnecessarily redundant since the last case effectively
8433 would also cover the first. No point in taking chances with these guys
8434 though ;-) Note that if you want an ad or obnoxious
8435 URL to be invisible, it should be defined as <quote>ad.doubleclick.net</quote>
8436 is done here -- as both a <link
8437 linkend="BLOCK"><quote>+block{}</quote></link>
8438 <emphasis>and</emphasis> an
8439 <link linkend="HANDLE-AS-IMAGE"><quote>+handle-as-image</quote></link>.
8440 The custom alias <quote><literal>+block-as-image</literal></quote> just
8441 simplifies the process and make it more readable.
8445 One last example. Let's try <quote>http://www.example.net/adsl/HOWTO/</quote>.
8446 This one is giving us problems. We are getting a blank page. Hmmm ...
8452 Matches for http://www.example.net/adsl/HOWTO/:
8454 In file: default.action <guibutton>[ View ]</guibutton> <guibutton>[ Edit ]</guibutton>
8458 +change-x-forwarded-for{block}
8459 -client-header-filter{hide-tor-exit-notation}
8460 -content-type-overwrite
8461 -crunch-client-header
8462 -crunch-if-none-match
8463 -crunch-incoming-cookies
8464 -crunch-outgoing-cookies
8465 -crunch-server-header
8467 -downgrade-http-version
8468 +fast-redirects {check-decoded-url}
8470 -filter {content-cookies}
8471 -filter {all-popups}
8472 -filter {banners-by-link}
8473 -filter {tiny-textforms}
8474 -filter {frameset-borders}
8475 -filter {demoronizer}
8476 -filter {shockwave-flash}
8477 -filter {quicktime-kioskmode}
8479 -filter {crude-parental}
8480 -filter {site-specifics}
8481 -filter {js-annoyances}
8482 -filter {html-annoyances}
8483 +filter {refresh-tags}
8484 -filter {unsolicited-popups}
8485 +filter {img-reorder}
8486 +filter {banners-by-size}
8488 +filter {jumping-windows}
8489 +filter {ie-exploits}
8496 -handle-as-empty-document
8498 -hide-accept-language
8499 -hide-content-disposition
8500 +hide-from-header{block}
8501 +hide-referer{forge}
8503 -overwrite-last-modified
8504 +prevent-compression
8506 -server-header-filter{xml-to-html}
8507 -server-header-filter{html-to-xml}
8508 +session-cookies-only
8509 +set-image-blocker{blank} }
8512 { +block{Path contains "ads".} +handle-as-image }
8518 Ooops, the <quote>/adsl/</quote> is matching <quote>/ads</quote> in our
8519 configuration! But we did not want this at all! Now we see why we get the
8520 blank page. It is actually triggering two different actions here, and
8521 the effects are aggregated so that the URL is blocked, and &my-app; is told
8522 to treat the block as if it were an image. But this is, of course, all wrong.
8523 We could now add a new action below this (or better in our own
8524 <filename>user.action</filename> file) that explicitly
8525 <emphasis>un</emphasis> blocks (
8526 <link linkend="BLOCK"><quote>{-block}</quote></link>) paths with
8527 <quote>adsl</quote> in them (remember, last match in the configuration
8528 wins). There are various ways to handle such exceptions. Example:
8540 Now the page displays ;-)
8541 Remember to flush your browser's caches when making these kinds of changes to
8542 your configuration to insure that you get a freshly delivered page! Or, try
8543 using <literal>Shift+Reload</literal>.
8547 But now what about a situation where we get no explicit matches like
8554 { +block{Path starts with "ads".} +handle-as-image }
8560 That actually was very helpful and pointed us quickly to where the problem
8561 was. If you don't get this kind of match, then it means one of the default
8562 rules in the first section of <filename>default.action</filename> is causing
8563 the problem. This would require some guesswork, and maybe a little trial and
8564 error to isolate the offending rule. One likely cause would be one of the
8565 <link linkend="FILTER"><quote>+filter</quote></link> actions.
8566 These tend to be harder to troubleshoot.
8567 Try adding the URL for the site to one of aliases that turn off
8568 <link linkend="FILTER"><quote>+filter</quote></link>:
8576 .worldpay.com # for quietpc.com
8584 <quote><literal>{ shop }</literal></quote> is an <quote>alias</quote> that expands to
8585 <quote><literal>{ -filter -session-cookies-only }</literal></quote>.
8586 Or you could do your own exception to negate filtering:
8594 # Disable ALL filter actions for sites in this section
8602 This would turn off all filtering for these sites. This is best
8603 put in <filename>user.action</filename>, for local site
8604 exceptions. Note that when a simple domain pattern is used by itself (without
8605 the subsequent path portion), all sub-pages within that domain are included
8606 automatically in the scope of the action.
8610 Images that are inexplicably being blocked, may well be hitting the
8611 <link linkend="FILTER-BANNERS-BY-SIZE"><quote>+filter{banners-by-size}</quote></link>
8613 that images of certain sizes are ad banners (works well
8614 <emphasis>most of the time</emphasis> since these tend to be standardized).
8618 <quote><literal>{ fragile }</literal></quote> is an alias that disables most
8619 actions that are the most likely to cause trouble. This can be used as a
8620 last resort for problem sites.
8626 # Handle with care: easy to break
8628 mybank.example.com</screen>
8633 <emphasis>Remember to flush caches!</emphasis> Note that the
8634 <literal>mail.google</literal> reference lacks the TLD portion (e.g.
8635 <quote>.com</quote>). This will effectively match any TLD with
8636 <literal>google</literal> in it, such as <literal>mail.google.de.</literal>,
8640 If this still does not work, you will have to go through the remaining
8641 actions one by one to find which one(s) is causing the problem.
8650 This program is free software; you can redistribute it
8651 and/or modify it under the terms of the GNU General
8652 Public License as published by the Free Software
8653 Foundation; either version 2 of the License, or (at
8654 your option) any later version.
8656 This program is distributed in the hope that it will
8657 be useful, but WITHOUT ANY WARRANTY; without even the
8658 implied warranty of MERCHANTABILITY or FITNESS FOR A
8659 PARTICULAR PURPOSE. See the GNU General Public
8660 License for more details.
8662 The GNU General Public License should be included with
8663 this file. If not, you can view it at
8664 http://www.gnu.org/copyleft/gpl.html
8665 or write to the Free Software Foundation, Inc.,
8666 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,