1 <!DOCTYPE article PUBLIC "-//OASIS//DTD DocBook V3.1//EN" [
2 <!entity % dummy "IGNORE">
3 <!entity supported SYSTEM "supported.sgml">
4 <!entity newfeatures SYSTEM "newfeatures.sgml">
5 <!entity p-intro SYSTEM "privoxy.sgml">
6 <!entity seealso SYSTEM "seealso.sgml">
7 <!entity buildsource SYSTEM "buildsource.sgml">
8 <!entity contacting SYSTEM "contacting.sgml">
9 <!entity history SYSTEM "history.sgml">
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 "3.0.22">
17 <!entity p-status "UNRELEASED">
18 <!entity % p-authors-formal "INCLUDE"> <!-- include additional text, etc -->
19 <!entity % p-not-stable "INCLUDE">
20 <!entity % p-stable "IGNORE">
21 <!entity % p-text "IGNORE"> <!-- define we are not a text only doc -->
22 <!entity % p-doc "INCLUDE"> <!-- and we are a formal doc -->
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 -->
28 <!entity % draft "IGNORE"> <!-- WIP stuff -->
29 <!entity % seealso-extra "INCLUDE"> <!-- extra stuff from seealso.sgml -->
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 2.196 2015/12/28 18:56:36 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 2.196 2015/12/28 18:56:36 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-windows">
1070 <title>Windows</title>
1072 Click on the &my-app; Icon to start <application>Privoxy</application>. If no configuration file is
1073 specified on the command line, <application>Privoxy</application> will look
1074 for a file named <filename>config.txt</filename>. Note that Windows will
1075 automatically start &my-app; when the system starts if you chose that option
1079 <application>Privoxy</application> can run with full Windows service functionality.
1080 On Windows only, the &my-app; program has two new command line arguments
1081 to install and uninstall &my-app; as a service. See the
1082 <link linkend="installation-pack-win">Windows Installation
1083 instructions</link> for details.
1087 <sect2 id="start-unices">
1088 <title>Solaris, NetBSD, FreeBSD, HP-UX and others</title>
1090 Example Unix startup command:
1094 # /usr/sbin/privoxy /etc/privoxy/config
1099 <sect2 id="start-os2">
1102 During installation, <application>Privoxy</application> is configured to
1103 start automatically when the system restarts. You can start it manually by
1104 double-clicking on the <application>Privoxy</application> icon in the
1105 <application>Privoxy</application> folder.
1109 <sect2 id="start-macosx">
1110 <title>Mac OS X</title>
1112 After downloading the privoxy software, unzip the downloaded file by
1113 double-clicking on the zip file icon. Then, double-click on the
1114 installer package icon and follow the installation process.
1117 The privoxy service will automatically start after a successful
1118 installation. In addition, the privoxy service will automatically
1119 start every time your computer starts up.
1122 To prevent the privoxy service from automatically starting when your
1123 computer starts up, remove or rename the folder named
1124 /Library/StartupItems/Privoxy.
1127 A simple application named Privoxy Utility has been created which
1128 enables administrators to easily start and stop the privoxy service.
1131 In addition, the Privoxy Utility presents a simple way for
1132 administrators to edit the various privoxy config files. A method
1133 to uninstall the software is also available.
1136 An administrator username and password must be supplied in order for
1137 the Privoxy Utility to perform any of the tasks.
1145 See the section <link linkend="cmdoptions">Command line options</link> for
1149 must find a better place for this paragraph
1152 The included default configuration files should give a reasonable starting
1153 point. Most of the per site configuration is done in the
1154 <ulink url="actions-file.html"><quote>actions</quote></ulink> files. These are
1155 where various cookie actions are defined, ad and banner blocking, and other
1156 aspects of <application>Privoxy</application> configuration. There are several
1157 such files included, with varying levels of aggressiveness.
1161 You will probably want to keep an eye out for sites for which you may prefer
1162 persistent cookies, and add these to your actions configuration as needed. By
1163 default, most of these will be accepted only during the current browser
1164 session (aka <quote>session cookies</quote>), unless you add them to the
1165 configuration. If you want the browser to handle this instead, you will need
1166 to edit <filename>user.action</filename> (or through the web based interface)
1167 and disable this feature. If you use more than one browser, it would make
1168 more sense to let <application>Privoxy</application> handle this. In which
1169 case, the browser(s) should be set to accept all cookies.
1173 Another feature where you will probably want to define exceptions for trusted
1174 sites is the popup-killing (through <ulink
1175 url="actions-file.html#FILTER-POPUPS"><quote>+filter{popups}</quote></ulink>),
1176 because your favorite shopping, banking, or leisure site may need
1177 popups (explained below).
1181 <application>Privoxy</application> does not support all of the optional HTTP/1.1
1182 features yet. In the unlikely event that you experience inexplicable problems
1183 with browsers that use HTTP/1.1 per default
1184 (like <application>Mozilla</application> or recent versions of I.E.), you might
1185 try to force HTTP/1.0 compatibility. For Mozilla, look under <literal>Edit ->
1186 Preferences -> Debug -> Networking</literal>.
1187 Alternatively, set the <quote>+downgrade-http-version</quote> config option in
1188 <filename>default.action</filename> which will downgrade your browser's HTTP
1189 requests from HTTP/1.1 to HTTP/1.0 before processing them.
1193 After running <application>Privoxy</application> for a while, you can
1194 start to fine tune the configuration to suit your personal, or site,
1195 preferences and requirements. There are many, many aspects that can
1196 be customized. <quote>Actions</quote>
1197 can be adjusted by pointing your browser to
1198 <ulink url="http://config.privoxy.org/">http://config.privoxy.org/</ulink>
1199 (shortcut: <ulink url="http://p.p/">http://p.p/</ulink>),
1200 and then follow the link to <quote>View & Change the Current Configuration</quote>.
1201 (This is an internal page and does not require Internet access.)
1205 In fact, various aspects of <application>Privoxy</application>
1206 configuration can be viewed from this page, including
1207 current configuration parameters, source code version numbers,
1208 the browser's request headers, and <quote>actions</quote> that apply
1209 to a given URL. In addition to the actions file
1210 editor mentioned above, <application>Privoxy</application> can also
1211 be turned <quote>on</quote> and <quote>off</quote> (toggled) from this page.
1215 If you encounter problems, try loading the page without
1216 <application>Privoxy</application>. If that helps, enter the URL where
1217 you have the problems into <ulink url="http://p.p/show-url-info">the browser
1218 based rule tracing utility</ulink>. See which rules apply and why, and
1219 then try turning them off for that site one after the other, until the problem
1220 is gone. When you have found the culprit, you might want to turn the rest on
1225 If the above paragraph sounds gibberish to you, you might want to <link
1226 linkend="actions-file">read more about the actions concept</link>
1227 or even dive deep into the <link linkend="actionsanat">Appendix
1232 If you can't get rid of the problem at all, think you've found a bug in
1233 Privoxy, want to propose a new feature or smarter rules, please see the
1234 section <link linkend="contact"><quote>Contacting the
1235 Developers</quote></link> below.
1240 <!-- ~~~~~ New section ~~~~~ -->
1241 <sect2 id="cmdoptions">
1242 <title>Command Line Options</title>
1244 <application>Privoxy</application> may be invoked with the following
1245 command-line options:
1253 <emphasis>--config-test</emphasis>
1256 Exit after loading the configuration files before binding to
1257 the listen address. The exit code signals whether or not the
1258 configuration files have been successfully loaded.
1261 If the exit code is 1, at least one of the configuration files
1262 is invalid, if it is 0, all the configuration files have been
1263 successfully loaded (but may still contain errors that can
1264 currently only be detected at run time).
1267 This option doesn't affect the log setting, combination with
1268 <emphasis>--no-daemon</emphasis> is recommended if a configured
1269 log file shouldn't be used.
1274 <emphasis>--version</emphasis>
1277 Print version info and exit. Unix only.
1282 <emphasis>--help</emphasis>
1285 Print short usage info and exit. Unix only.
1290 <emphasis>--no-daemon</emphasis>
1293 Don't become a daemon, i.e. don't fork and become process group
1294 leader, and don't detach from controlling tty. Unix only.
1299 <emphasis>--pidfile FILE</emphasis>
1302 On startup, write the process ID to <emphasis>FILE</emphasis>. Delete the
1303 <emphasis>FILE</emphasis> on exit. Failure to create or delete the
1304 <emphasis>FILE</emphasis> is non-fatal. If no <emphasis>FILE</emphasis>
1305 option is given, no PID file will be used. Unix only.
1310 <emphasis>--user USER[.GROUP]</emphasis>
1313 After (optionally) writing the PID file, assume the user ID of
1314 <emphasis>USER</emphasis>, and if included the GID of GROUP. Exit if the
1315 privileges are not sufficient to do so. Unix only.
1320 <emphasis>--chroot</emphasis>
1323 Before changing to the user ID given in the <emphasis>--user</emphasis> option,
1324 chroot to that user's home directory, i.e. make the kernel pretend to the &my-app;
1325 process that the directory tree starts there. If set up carefully, this can limit
1326 the impact of possible vulnerabilities in &my-app; to the files contained in that hierarchy.
1332 <emphasis>--pre-chroot-nslookup hostname</emphasis>
1335 Specifies a hostname (for example www.privoxy.org) to look up before doing a chroot.
1336 On some systems, initializing the resolver library involves reading config files from
1337 /etc and/or loading additional shared libraries from /lib.
1338 On these systems, doing a hostname lookup before the chroot reduces
1339 the number of files that must be copied into the chroot tree.
1342 For fastest startup speed, a good value is a hostname that is not in /etc/hosts but that
1343 your local name server (listed in /etc/resolv.conf) can resolve without recursion
1344 (that is, without having to ask any other name servers). The hostname need not exist,
1345 but if it doesn't, an error message (which can be ignored) will be output.
1351 <emphasis>configfile</emphasis>
1354 If no <emphasis>configfile</emphasis> is included on the command line,
1355 <application>Privoxy</application> will look for a file named
1356 <quote>config</quote> in the current directory (except on Win32
1357 where it will look for <quote>config.txt</quote> instead). Specify
1358 full path to avoid confusion. If no config file is found,
1359 <application>Privoxy</application> will fail to start.
1367 On <application>MS Windows</application> only there are two additional
1368 command-line options to allow <application>Privoxy</application> to install and
1369 run as a <emphasis>service</emphasis>. See the
1370 <link linkend="installation-pack-win">Window Installation section</link>
1378 <!-- ~ End section ~ -->
1381 <!-- ~~~~~ New section ~~~~~ -->
1382 <sect1 id="configuration"><title>Privoxy Configuration</title>
1384 All <application>Privoxy</application> configuration is stored
1385 in text files. These files can be edited with a text editor.
1386 Many important aspects of <application>Privoxy</application> can
1387 also be controlled easily with a web browser.
1391 <!-- ~~~~~ New section ~~~~~ -->
1394 <title>Controlling Privoxy with Your Web Browser</title>
1396 <application>Privoxy</application>'s user interface can be reached through the special
1397 URL <ulink url="http://config.privoxy.org/">http://config.privoxy.org/</ulink>
1398 (shortcut: <ulink url="http://p.p/">http://p.p/</ulink>),
1399 which is a built-in page and works without Internet access.
1400 You will see the following section:
1404 <!-- Needs to be put in a table and colorized -->
1407 <bridgehead renderas="sect2"> Privoxy Menu</bridgehead>
1411 ▪ <ulink url="http://config.privoxy.org/show-status">View & change the current configuration</ulink>
1414 ▪ <ulink url="http://config.privoxy.org/show-version">View the source code version numbers</ulink>
1417 ▪ <ulink url="http://config.privoxy.org/show-request">View the request headers.</ulink>
1420 ▪ <ulink url="http://config.privoxy.org/show-url-info">Look up which actions apply to a URL and why</ulink>
1423 ▪ <ulink url="http://config.privoxy.org/toggle">Toggle Privoxy on or off</ulink>
1426 ▪ <ulink
1427 url="http://www.privoxy.org/&p-version;/user-manual/">Documentation</ulink>
1435 This should be self-explanatory. Note the first item leads to an editor for the
1436 <link linkend="actions-file">actions files</link>, which is where the ad, banner,
1437 cookie, and URL blocking magic is configured as well as other advanced features of
1438 <application>Privoxy</application>. This is an easy way to adjust various
1439 aspects of <application>Privoxy</application> configuration. The actions
1440 file, and other configuration files, are explained in detail below.
1444 <quote>Toggle Privoxy On or Off</quote> is handy for sites that might
1445 have problems with your current actions and filters. You can in fact use
1446 it as a test to see whether it is <application>Privoxy</application>
1447 causing the problem or not. <application>Privoxy</application> continues
1448 to run as a proxy in this case, but all manipulation is disabled, i.e.
1449 <application>Privoxy</application> acts like a normal forwarding proxy.
1453 Note that several of the features described above are disabled by default
1454 in <application>Privoxy</application> 3.0.7 beta and later.
1456 <ulink url="config.html">configuration file</ulink> to learn why
1457 and in which cases it's safe to enable them again.
1462 <!-- ~ End section ~ -->
1467 <!-- ~~~~~ New section ~~~~~ -->
1469 <sect2 id="confoverview">
1470 <title>Configuration Files Overview</title>
1472 For Unix, *BSD and Linux, all configuration files are located in
1473 <filename>/etc/privoxy/</filename> by default. For MS Windows, OS/2, and
1474 AmigaOS these are all in the same directory as the
1475 <application>Privoxy</application> executable. <![%p-not-stable;[ The name
1476 and number of configuration files has changed from previous versions, and is
1477 subject to change as development progresses.]]>
1481 The installed defaults provide a reasonable starting point, though
1482 some settings may be aggressive by some standards. For the time being, the
1483 principle configuration files are:
1491 The <link linkend="config">main configuration file</link> is named <filename>config</filename>
1492 on Linux, Unix, BSD, OS/2, and AmigaOS and <filename>config.txt</filename>
1493 on Windows. This is a required file.
1499 <filename>match-all.action</filename> is used to define which <quote>actions</quote>
1500 relating to banner-blocking, images, pop-ups, content modification, cookie handling
1501 etc should be applied by default. It should be the first actions file loaded.
1504 <filename>default.action</filename> defines many exceptions (both positive and negative)
1505 from the default set of actions that's configured in <filename>match-all.action</filename>.
1506 It should be the second actions file loaded and shouldn't be edited by the user.
1509 Multiple actions files may be defined in <filename>config</filename>. These
1510 are processed in the order they are defined. Local customizations and locally
1511 preferred exceptions to the default policies as defined in
1512 <filename>match-all.action</filename> (which you will most probably want
1513 to define sooner or later) are best applied in <filename>user.action</filename>,
1514 where you can preserve them across upgrades. The file isn't installed by all
1515 installers, but you can easily create it yourself with a text editor.
1518 There is also a web based editor that can be accessed from
1520 url="http://config.privoxy.org/show-status">http://config.privoxy.org/show-status</ulink>
1522 url="http://p.p/show-status">http://p.p/show-status</ulink>) for the
1523 various actions files.
1529 <quote>Filter files</quote> (the <link linkend="filter-file">filter
1530 file</link>) can be used to re-write the raw page content, including
1531 viewable text as well as embedded HTML and JavaScript, and whatever else
1532 lurks on any given web page. The filtering jobs are only pre-defined here;
1533 whether to apply them or not is up to the actions files.
1534 <filename>default.filter</filename> includes various filters made
1535 available for use by the developers. Some are much more intrusive than
1536 others, and all should be used with caution. You may define additional
1537 filter files in <filename>config</filename> as you can with
1538 actions files. We suggest <filename>user.filter</filename> for any
1539 locally defined filters or customizations.
1547 The syntax of the configuration and filter files may change between different
1548 Privoxy versions, unfortunately some enhancements cost backwards compatibility.
1549 <!-- Add link to documentation-->
1553 All files use the <quote><literal>#</literal></quote> character to denote a
1554 comment (the rest of the line will be ignored) and understand line continuation
1555 through placing a backslash ("<literal>\</literal>") as the very last character
1556 in a line. If the <literal>#</literal> is preceded by a backslash, it looses
1557 its special function. Placing a <literal>#</literal> in front of an otherwise
1558 valid configuration line to prevent it from being interpreted is called "commenting
1559 out" that line. Blank lines are ignored.
1563 The actions files and filter files
1564 can use Perl style <link linkend="regex">regular expressions</link> for
1565 maximum flexibility.
1569 After making any changes, there is no need to restart
1570 <application>Privoxy</application> in order for the changes to take
1571 effect. <application>Privoxy</application> detects such changes
1572 automatically. Note, however, that it may take one or two additional
1573 requests for the change to take effect. When changing the listening address
1574 of <application>Privoxy</application>, these <quote>wake up</quote> requests
1575 must obviously be sent to the <emphasis>old</emphasis> listening address.
1580 While under development, the configuration content is subject to change.
1581 The below documentation may not be accurate by the time you read this.
1582 Also, what constitutes a <quote>default</quote> setting, may change, so
1583 please check all your configuration files on important issues.
1589 <!-- ~ End section ~ -->
1592 <!-- ~~~~~~~~ New section Header ~~~~~~~~~ -->
1594 <!-- **************************************************** -->
1595 <!-- Include config.sgml here -->
1596 <!-- This is where the entire config file is detailed. -->
1598 <!-- end include -->
1601 <!-- ~ End section ~ -->
1605 <!-- ~~~~~~~~ New section Header ~~~~~~~~~ -->
1607 <sect1 id="actions-file"><title>Actions Files</title>
1611 XXX: similar descriptions are in the Configuration Files sections.
1612 We should only describe them at one place.
1615 The actions files are used to define what <emphasis>actions</emphasis>
1616 <application>Privoxy</application> takes for which URLs, and thus determines
1617 how ad images, cookies and various other aspects of HTTP content and
1618 transactions are handled, and on which sites (or even parts thereof).
1619 There are a number of such actions, with a wide range of functionality.
1620 Each action does something a little different.
1621 These actions give us a veritable arsenal of tools with which to exert
1622 our control, preferences and independence. Actions can be combined so that
1623 their effects are aggregated when applied against a given set of URLs.
1627 are three action files included with <application>Privoxy</application> with
1634 <filename>match-all.action</filename> - is used to define which
1635 <quote>actions</quote> relating to banner-blocking, images, pop-ups,
1636 content modification, cookie handling etc should be applied by default.
1637 It should be the first actions file loaded
1642 <filename>default.action</filename> - defines many exceptions (both
1643 positive and negative) from the default set of actions that's configured
1644 in <filename>match-all.action</filename>. It is a set of rules that should
1645 work reasonably well as-is for most users. This file is only supposed to
1646 be edited by the developers. It should be the second actions file loaded.
1651 <filename>user.action</filename> - is intended to be for local site
1652 preferences and exceptions. As an example, if your ISP or your bank
1653 has specific requirements, and need special handling, this kind of
1654 thing should go here. This file will not be upgraded.
1659 <guibutton>Edit</guibutton> <guibutton>Set to Cautious</guibutton> <guibutton>Set to Medium</guibutton> <guibutton>Set to Advanced</guibutton>
1662 These have increasing levels of aggressiveness <emphasis>and have no
1663 influence on your browsing unless you select them explicitly in the
1664 editor</emphasis>. A default installation should be pre-set to
1665 <literal>Cautious</literal>. New users should try this for a while before
1666 adjusting the settings to more aggressive levels. The more aggressive
1667 the settings, then the more likelihood there is of problems such as sites
1668 not working as they should.
1671 The <guibutton>Edit</guibutton> button allows you to turn each
1672 action on/off individually for fine-tuning. The <guibutton>Cautious</guibutton>
1673 button changes the actions list to low/safe settings which will activate
1674 ad blocking and a minimal set of &my-app;'s features, and subsequently
1675 there will be less of a chance for accidental problems. The
1676 <guibutton>Medium</guibutton> button sets the list to a medium level of
1677 other features and a low level set of privacy features. The
1678 <guibutton>Advanced</guibutton> button sets the list to a high level of
1679 ad blocking and medium level of privacy. See the chart below. The latter
1680 three buttons over-ride any changes via with the
1681 <guibutton>Edit</guibutton> button. More fine-tuning can be done in the
1682 lower sections of this internal page.
1685 While the actions file editor allows to enable these settings in all
1686 actions files, they are only supposed to be enabled in the first one
1687 to make sure you don't unintentionally overrule earlier rules.
1690 The default profiles, and their associated actions, as pre-defined in
1691 <filename>default.action</filename> are:
1694 <table frame=all><title>Default Configurations</title>
1695 <tgroup cols=4 align=left colsep=1 rowsep=1>
1696 <colspec colname=c1>
1697 <colspec colname=c2>
1698 <colspec colname=c3>
1699 <colspec colname=c4>
1702 <entry>Feature</entry>
1703 <entry>Cautious</entry>
1704 <entry>Medium</entry>
1705 <entry>Advanced</entry>
1710 <!-- <entry>f1</entry> -->
1711 <!-- <entry>f2</entry> -->
1712 <!-- <entry>f3</entry> -->
1713 <!-- <entry>f4</entry> -->
1719 <entry>Ad-blocking Aggressiveness</entry>
1720 <entry>medium</entry>
1726 <entry>Ad-filtering by size</entry>
1733 <entry>Ad-filtering by link</entry>
1739 <entry>Pop-up killing</entry>
1740 <entry>blocks only</entry>
1741 <entry>blocks only</entry>
1742 <entry>blocks only</entry>
1746 <entry>Privacy Features</entry>
1748 <entry>medium</entry>
1749 <entry>medium/high</entry>
1753 <entry>Cookie handling</entry>
1755 <entry>session-only</entry>
1760 <entry>Referer forging</entry>
1767 <entry>GIF de-animation</entry>
1774 <entry>Fast redirects</entry>
1781 <entry>HTML taming</entry>
1788 <entry>JavaScript taming</entry>
1795 <entry>Web-bug killing</entry>
1802 <entry>Image tag reordering</entry>
1818 The list of actions files to be used are defined in the main configuration
1819 file, and are processed in the order they are defined (e.g.
1820 <filename>default.action</filename> is typically processed before
1821 <filename>user.action</filename>). The content of these can all be viewed and
1823 url="http://config.privoxy.org/show-status">http://config.privoxy.org/show-status</ulink>.
1824 The over-riding principle when applying actions, is that the last action that
1825 matches a given URL wins. The broadest, most general rules go first
1826 (defined in <filename>default.action</filename>),
1827 followed by any exceptions (typically also in
1828 <filename>default.action</filename>), which are then followed lastly by any
1829 local preferences (typically in <emphasis>user</emphasis><filename>.action</filename>).
1830 Generally, <filename>user.action</filename> has the last word.
1834 An actions file typically has multiple sections. If you want to use
1835 <quote>aliases</quote> in an actions file, you have to place the (optional)
1836 <link linkend="aliases">alias section</link> at the top of that file.
1837 Then comes the default set of rules which will apply universally to all
1838 sites and pages (be <emphasis>very careful</emphasis> with using such a
1839 universal set in <filename>user.action</filename> or any other actions file after
1840 <filename>default.action</filename>, because it will override the result
1841 from consulting any previous file). And then below that,
1842 exceptions to the defined universal policies. You can regard
1843 <filename>user.action</filename> as an appendix to <filename>default.action</filename>,
1844 with the advantage that it is a separate file, which makes preserving your
1845 personal settings across <application>Privoxy</application> upgrades easier.
1849 Actions can be used to block anything you want, including ads, banners, or
1850 just some obnoxious URL whose content you would rather not see. Cookies can be accepted
1851 or rejected, or accepted only during the current browser session (i.e. not
1852 written to disk), content can be modified, some JavaScripts tamed, user-tracking
1853 fooled, and much more. See below for a <link linkend="actions">complete list
1857 <!-- ~~~~~ New section ~~~~~ -->
1859 <title>Finding the Right Mix</title>
1861 Note that some <link linkend="actions">actions</link>, like cookie suppression
1862 or script disabling, may render some sites unusable that rely on these
1863 techniques to work properly. Finding the right mix of actions is not always easy and
1864 certainly a matter of personal taste. And, things can always change, requiring
1865 refinements in the configuration. In general, it can be said that the more
1866 <quote>aggressive</quote> your default settings (in the top section of the
1867 actions file) are, the more exceptions for <quote>trusted</quote> sites you
1868 will have to make later. If, for example, you want to crunch all cookies per
1869 default, you'll have to make exceptions from that rule for sites that you
1870 regularly use and that require cookies for actually useful purposes, like maybe
1871 your bank, favorite shop, or newspaper.
1875 We have tried to provide you with reasonable rules to start from in the
1876 distribution actions files. But there is no general rule of thumb on these
1877 things. There just are too many variables, and sites are constantly changing.
1878 Sooner or later you will want to change the rules (and read this chapter again :).
1882 <!-- ~~~~~ New section ~~~~~ -->
1884 <title>How to Edit</title>
1886 The easiest way to edit the actions files is with a browser by
1887 using our browser-based editor, which can be reached from <ulink
1888 url="http://config.privoxy.org/show-status">http://config.privoxy.org/show-status</ulink>.
1889 Note: the config file option <link
1890 linkend="enable-edit-actions">enable-edit-actions</link> must be enabled for
1891 this to work. The editor allows both fine-grained control over every single
1892 feature on a per-URL basis, and easy choosing from wholesale sets of defaults
1893 like <quote>Cautious</quote>, <quote>Medium</quote> or
1894 <quote>Advanced</quote>. Warning: the <quote>Advanced</quote> setting is more
1895 aggressive, and will be more likely to cause problems for some sites.
1896 Experienced users only!
1900 If you prefer plain text editing to GUIs, you can of course also directly edit the
1901 the actions files with your favorite text editor. Look at
1902 <filename>default.action</filename> which is richly commented with many
1908 <sect2 id="actions-apply">
1909 <title>How Actions are Applied to Requests</title>
1911 Actions files are divided into sections. There are special sections,
1912 like the <quote><link linkend="aliases">alias</link></quote> sections which will
1913 be discussed later. For now let's concentrate on regular sections: They have a
1914 heading line (often split up to multiple lines for readability) which consist
1915 of a list of actions, separated by whitespace and enclosed in curly braces.
1916 Below that, there is a list of URL and tag patterns, each on a separate line.
1920 To determine which actions apply to a request, the URL of the request is
1921 compared to all URL patterns in each <quote>action file</quote>.
1922 Every time it matches, the list of applicable actions for the request is
1923 incrementally updated, using the heading of the section in which the
1924 pattern is located. The same is done again for tags and tag patterns later on.
1928 If multiple applying sections set the same action differently,
1929 the last match wins. If not, the effects are aggregated.
1930 E.g. a URL might match a regular section with a heading line of <literal>{
1931 +<link linkend="handle-as-image">handle-as-image</link> }</literal>,
1932 then later another one with just <literal>{
1933 +<link linkend="block">block</link> }</literal>, resulting
1934 in <emphasis>both</emphasis> actions to apply. And there may well be
1935 cases where you will want to combine actions together. Such a section then
1941 { +<literal>handle-as-image</literal> +<literal>block{Banner ads.}</literal> }
1942 # Block these as if they were images. Send no block page.
1944 media.example.com/.*banners
1945 .example.com/images/ads/</screen>
1949 You can trace this process for URL patterns and any given URL by visiting <ulink
1950 url="http://config.privoxy.org/show-url-info">http://config.privoxy.org/show-url-info</ulink>.
1954 Examples and more detail on this is provided in the Appendix, <link linkend="ACTIONSANAT">
1955 Troubleshooting: Anatomy of an Action</link> section.
1959 <!-- ~~~~~ New section ~~~~~ -->
1960 <sect2 id="af-patterns">
1961 <title>Patterns</title>
1963 As mentioned, <application>Privoxy</application> uses <quote>patterns</quote>
1964 to determine what <emphasis>actions</emphasis> might apply to which sites and
1965 pages your browser attempts to access. These <quote>patterns</quote> use wild
1966 card type <emphasis>pattern</emphasis> matching to achieve a high degree of
1967 flexibility. This allows one expression to be expanded and potentially match
1968 against many similar patterns.
1972 Generally, an URL pattern has the form
1973 <literal><host><port>/<path></literal>, where the
1974 <literal><host></literal>, the <literal><port></literal>
1975 and the <literal><path></literal> are optional. (This is why the special
1976 <literal>/</literal> pattern matches all URLs). Note that the protocol
1977 portion of the URL pattern (e.g. <literal>http://</literal>) should
1978 <emphasis>not</emphasis> be included in the pattern. This is assumed already!
1981 The pattern matching syntax is different for the host and path parts of
1982 the URL. The host part uses a simple globbing type matching technique,
1983 while the path part uses more flexible
1984 <ulink url="http://en.wikipedia.org/wiki/Regular_expressions"><quote>Regular
1985 Expressions</quote></ulink> (POSIX 1003.2).
1988 The port part of a pattern is a decimal port number preceded by a colon
1989 (<literal>:</literal>). If the host part contains a numerical IPv6 address,
1990 it has to be put into angle brackets
1991 (<literal><</literal>, <literal>></literal>).
1996 <term><literal>www.example.com/</literal></term>
1999 is a host-only pattern and will match any request to <literal>www.example.com</literal>,
2000 regardless of which document on that server is requested. So ALL pages in
2001 this domain would be covered by the scope of this action. Note that a
2002 simple <literal>example.com</literal> is different and would NOT match.
2007 <term><literal>www.example.com</literal></term>
2010 means exactly the same. For host-only patterns, the trailing <literal>/</literal> may
2016 <term><literal>www.example.com/index.html</literal></term>
2019 matches all the documents on <literal>www.example.com</literal>
2020 whose name starts with <literal>/index.html</literal>.
2025 <term><literal>www.example.com/index.html$</literal></term>
2028 matches only the single document <literal>/index.html</literal>
2029 on <literal>www.example.com</literal>.
2034 <term><literal>/index.html$</literal></term>
2037 matches the document <literal>/index.html</literal>, regardless of the domain,
2038 i.e. on <emphasis>any</emphasis> web server anywhere.
2043 <term><literal>/</literal></term>
2046 Matches any URL because there's no requirement for either the
2047 domain or the path to match anything.
2052 <term><literal>:8000/</literal></term>
2055 Matches any URL pointing to TCP port 8000.
2060 <term><literal>10.0.0.1/</literal></term>
2063 Matches any URL with the host address <literal>10.0.0.1</literal>.
2064 (Note that the real URL uses plain brackets, not angle brackets.)
2069 <term><literal><2001:db8::1>/</literal></term>
2072 Matches any URL with the host address <literal>2001:db8::1</literal>.
2073 (Note that the real URL uses plain brackets, not angle brackets.)
2078 <term><literal>index.html</literal></term>
2081 matches nothing, since it would be interpreted as a domain name and
2082 there is no top-level domain called <literal>.html</literal>. So its
2090 <!-- ~~~~~ New section ~~~~~ -->
2091 <sect3 id="host-pattern"><title>The Host Pattern</title>
2094 The matching of the host part offers some flexible options: if the
2095 host pattern starts or ends with a dot, it becomes unanchored at that end.
2096 The host pattern is often referred to as domain pattern as it is usually
2097 used to match domain names and not IP addresses.
2103 <term><literal>.example.com</literal></term>
2106 matches any domain with first-level domain <literal>com</literal>
2107 and second-level domain <literal>example</literal>.
2108 For example <literal>www.example.com</literal>,
2109 <literal>example.com</literal> and <literal>foo.bar.baz.example.com</literal>.
2110 Note that it wouldn't match if the second-level domain was <literal>another-example</literal>.
2115 <term><literal>www.</literal></term>
2118 matches any domain that <emphasis>STARTS</emphasis> with
2119 <literal>www.</literal> (It also matches the domain
2120 <literal>www</literal> but most of the time that doesn't matter.)
2125 <term><literal>.example.</literal></term>
2128 matches any domain that <emphasis>CONTAINS</emphasis> <literal>.example.</literal>.
2129 And, by the way, also included would be any files or documents that exist
2130 within that domain since no path limitations are specified. (Correctly
2131 speaking: It matches any FQDN that contains <literal>example</literal> as
2132 a domain.) This might be <literal>www.example.com</literal>,
2133 <literal>news.example.de</literal>, or
2134 <literal>www.example.net/cgi/testing.pl</literal> for instance. All these
2142 Additionally, there are wild-cards that you can use in the domain names
2143 themselves. These work similarly to shell globbing type wild-cards:
2144 <quote>*</quote> represents zero or more arbitrary characters (this is
2146 <ulink url="http://en.wikipedia.org/wiki/Regular_expressions"><quote>Regular
2147 Expression</quote></ulink> based syntax of <quote>.*</quote>),
2148 <quote>?</quote> represents any single character (this is equivalent to the
2149 regular expression syntax of a simple <quote>.</quote>), and you can define
2150 <quote>character classes</quote> in square brackets which is similar to
2151 the same regular expression technique. All of this can be freely mixed:
2156 <term><literal>ad*.example.com</literal></term>
2159 matches <quote>adserver.example.com</quote>,
2160 <quote>ads.example.com</quote>, etc but not <quote>sfads.example.com</quote>
2165 <term><literal>*ad*.example.com</literal></term>
2168 matches all of the above, and then some.
2173 <term><literal>.?pix.com</literal></term>
2176 matches <literal>www.ipix.com</literal>,
2177 <literal>pictures.epix.com</literal>, <literal>a.b.c.d.e.upix.com</literal> etc.
2182 <term><literal>www[1-9a-ez].example.c*</literal></term>
2185 matches <literal>www1.example.com</literal>,
2186 <literal>www4.example.cc</literal>, <literal>wwwd.example.cy</literal>,
2187 <literal>wwwz.example.com</literal> etc., but <emphasis>not</emphasis>
2188 <literal>wwww.example.com</literal>.
2195 While flexible, this is not the sophistication of full regular expression based syntax.
2200 <!-- ~ End section ~ -->
2203 <!-- ~~~~~ New section ~~~~~ -->
2204 <sect3><title>The Path Pattern</title>
2207 <application>Privoxy</application> uses <quote>modern</quote> POSIX 1003.2
2208 <ulink url="http://en.wikipedia.org/wiki/Regular_expressions"><quote>Regular
2209 Expressions</quote></ulink> for matching the path portion (after the slash),
2210 and is thus more flexible.
2214 There is an <link linkend="regex">Appendix</link> with a brief quick-start into regular
2215 expressions, you also might want to have a look at your operating system's documentation
2216 on regular expressions (try <literal>man re_format</literal>).
2220 Note that the path pattern is automatically left-anchored at the <quote>/</quote>,
2221 i.e. it matches as if it would start with a <quote>^</quote> (regular expression speak
2222 for the beginning of a line).
2226 Please also note that matching in the path is <emphasis>CASE INSENSITIVE</emphasis>
2227 by default, but you can switch to case sensitive at any point in the pattern by using the
2228 <quote>(?-i)</quote> switch: <literal>www.example.com/(?-i)PaTtErN.*</literal> will match
2229 only documents whose path starts with <literal>PaTtErN</literal> in
2230 <emphasis>exactly</emphasis> this capitalization.
2235 <term><literal>.example.com/.*</literal></term>
2238 Is equivalent to just <quote>.example.com</quote>, since any documents
2239 within that domain are matched with or without the <quote>.*</quote>
2240 regular expression. This is redundant
2245 <term><literal>.example.com/.*/index.html$</literal></term>
2248 Will match any page in the domain of <quote>example.com</quote> that is
2249 named <quote>index.html</quote>, and that is part of some path. For
2250 example, it matches <quote>www.example.com/testing/index.html</quote> but
2251 NOT <quote>www.example.com/index.html</quote> because the regular
2252 expression called for at least two <quote>/'s</quote>, thus the path
2253 requirement. It also would match
2254 <quote>www.example.com/testing/index_html</quote>, because of the
2255 special meta-character <quote>.</quote>.
2260 <term><literal>.example.com/(.*/)?index\.html$</literal></term>
2263 This regular expression is conditional so it will match any page
2264 named <quote>index.html</quote> regardless of path which in this case can
2265 have one or more <quote>/'s</quote>. And this one must contain exactly
2266 <quote>.html</quote> (but does not have to end with that!).
2271 <term><literal>.example.com/(.*/)(ads|banners?|junk)</literal></term>
2274 This regular expression will match any path of <quote>example.com</quote>
2275 that contains any of the words <quote>ads</quote>, <quote>banner</quote>,
2276 <quote>banners</quote> (because of the <quote>?</quote>) or <quote>junk</quote>.
2277 The path does not have to end in these words, just contain them.
2282 <term><literal>.example.com/(.*/)(ads|banners?|junk)/.*\.(jpe?g|gif|png)$</literal></term>
2285 This is very much the same as above, except now it must end in either
2286 <quote>.jpg</quote>, <quote>.jpeg</quote>, <quote>.gif</quote> or <quote>.png</quote>. So this
2287 one is limited to common image formats.
2294 There are many, many good examples to be found in <filename>default.action</filename>,
2295 and more tutorials below in <link linkend="regex">Appendix on regular expressions</link>.
2300 <!-- ~ End section ~ -->
2303 <!-- ~~~~~ New section ~~~~~ -->
2304 <sect3 id="tag-pattern"><title>The Tag Pattern</title>
2307 Tag patterns are used to change the applying actions based on the
2308 request's tags. Tags can be created with either the
2309 <link linkend="CLIENT-HEADER-TAGGER">client-header-tagger</link>
2310 or the <link linkend="SERVER-HEADER-TAGGER">server-header-tagger</link> action.
2314 Tag patterns have to start with <quote>TAG:</quote>, so &my-app;
2315 can tell them apart from URL patterns. Everything after the colon
2316 including white space, is interpreted as a regular expression with
2317 path pattern syntax, except that tag patterns aren't left-anchored
2318 automatically (&my-app; doesn't silently add a <quote>^</quote>,
2319 you have to do it yourself if you need it).
2323 To match all requests that are tagged with <quote>foo</quote>
2324 your pattern line should be <quote>TAG:^foo$</quote>,
2325 <quote>TAG:foo</quote> would work as well, but it would also
2326 match requests whose tags contain <quote>foo</quote> somewhere.
2327 <quote>TAG: foo</quote> wouldn't work as it requires white space.
2331 Sections can contain URL and tag patterns at the same time,
2332 but tag patterns are checked after the URL patterns and thus
2333 always overrule them, even if they are located before the URL patterns.
2337 Once a new tag is added, Privoxy checks right away if it's matched by one
2338 of the tag patterns and updates the action settings accordingly. As a result
2339 tags can be used to activate other tagger actions, as long as these other
2340 taggers look for headers that haven't already be parsed.
2344 For example you could tag client requests which use the
2345 <literal>POST</literal> method,
2346 then use this tag to activate another tagger that adds a tag if cookies
2347 are sent, and then use a block action based on the cookie tag. This allows
2348 the outcome of one action, to be input into a subsequent action. However if
2349 you'd reverse the position of the described taggers, and activated the
2350 method tagger based on the cookie tagger, no method tags would be created.
2351 The method tagger would look for the request line, but at the time
2352 the cookie tag is created, the request line has already been parsed.
2356 While this is a limitation you should be aware of, this kind of
2357 indirection is seldom needed anyway and even the example doesn't
2358 make too much sense.
2363 <!-- ~~~~~ New section ~~~~~ -->
2364 <sect3 id="negative-tag-patterns"><title>The Negative Tag Patterns</title>
2367 To match requests that do not have a certain tag, specify a negative tag pattern
2368 by prefixing the tag pattern line with either <quote>NO-REQUEST-TAG:</quote>
2369 or <quote>NO-RESPONSE-TAG:</quote> instead of <quote>TAG:</quote>.
2373 Negative tag patterns created with <quote>NO-REQUEST-TAG:</quote> are checked
2374 after all client headers are scanned, the ones created with <quote>NO-RESPONSE-TAG:</quote>
2375 are checked after all server headers are scanned. In both cases all the created
2376 tags are considered.
2382 <!-- ~ End section ~ -->
2385 <!-- ~~~~~ New section ~~~~~ -->
2387 <sect2 id="actions">
2388 <title>Actions</title>
2390 All actions are disabled by default, until they are explicitly enabled
2391 somewhere in an actions file. Actions are turned on if preceded with a
2392 <quote>+</quote>, and turned off if preceded with a <quote>-</quote>. So a
2393 <literal>+action</literal> means <quote>do that action</quote>, e.g.
2394 <literal>+block</literal> means <quote>please block URLs that match the
2395 following patterns</quote>, and <literal>-block</literal> means <quote>don't
2396 block URLs that match the following patterns, even if <literal>+block</literal>
2397 previously applied.</quote>
2402 Again, actions are invoked by placing them on a line, enclosed in curly braces and
2403 separated by whitespace, like in
2404 <literal>{+some-action -some-other-action{some-parameter}}</literal>,
2405 followed by a list of URL patterns, one per line, to which they apply.
2406 Together, the actions line and the following pattern lines make up a section
2407 of the actions file.
2411 Actions fall into three categories:
2418 Boolean, i.e the action can only be <quote>enabled</quote> or
2419 <quote>disabled</quote>. Syntax:
2423 +<replaceable class="function">name</replaceable> # enable action <replaceable class="parameter">name</replaceable>
2424 -<replaceable class="function">name</replaceable> # disable action <replaceable class="parameter">name</replaceable></screen>
2427 Example: <literal>+handle-as-image</literal>
2434 Parameterized, where some value is required in order to enable this type of action.
2439 +<replaceable class="function">name</replaceable>{<replaceable class="parameter">param</replaceable>} # enable action and set parameter to <replaceable class="parameter">param</replaceable>,
2440 # overwriting parameter from previous match if necessary
2441 -<replaceable class="function">name</replaceable> # disable action. The parameter can be omitted</screen>
2444 Note that if the URL matches multiple positive forms of a parameterized action,
2445 the last match wins, i.e. the params from earlier matches are simply ignored.
2448 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>
2454 Multi-value. These look exactly like parameterized actions,
2455 but they behave differently: If the action applies multiple times to the
2456 same URL, but with different parameters, <emphasis>all</emphasis> the parameters
2457 from <emphasis>all</emphasis> matches are remembered. This is used for actions
2458 that can be executed for the same request repeatedly, like adding multiple
2459 headers, or filtering through multiple filters. Syntax:
2463 +<replaceable class="function">name</replaceable>{<replaceable class="parameter">param</replaceable>} # enable action and add <replaceable class="parameter">param</replaceable> to the list of parameters
2464 -<replaceable class="function">name</replaceable>{<replaceable class="parameter">param</replaceable>} # remove the parameter <replaceable class="parameter">param</replaceable> from the list of parameters
2465 # If it was the last one left, disable the action.
2466 <replaceable class="parameter">-name</replaceable> # disable this action completely and remove all parameters from the list</screen>
2469 Examples: <literal>+add-header{X-Fun-Header: Some text}</literal> and
2470 <literal>+filter{html-annoyances}</literal>
2478 If nothing is specified in any actions file, no <quote>actions</quote> are
2479 taken. So in this case <application>Privoxy</application> would just be a
2480 normal, non-blocking, non-filtering proxy. You must specifically enable the
2481 privacy and blocking features you need (although the provided default actions
2482 files will give a good starting point).
2486 Later defined action sections always over-ride earlier ones of the same type.
2487 So exceptions to any rules you make, should come in the latter part of the file (or
2488 in a file that is processed later when using multiple actions files such
2489 as <filename>user.action</filename>). For multi-valued actions, the actions
2490 are applied in the order they are specified. Actions files are processed in
2491 the order they are defined in <filename>config</filename> (the default
2492 installation has three actions files). It also quite possible for any given
2493 URL to match more than one <quote>pattern</quote> (because of wildcards and
2494 regular expressions), and thus to trigger more than one set of actions! Last
2498 <!-- start actions listing -->
2500 The list of valid <application>Privoxy</application> actions are:
2504 <!-- ********************************************************** -->
2505 <!-- Please note the below defined actions use id's that are -->
2506 <!-- probably linked from other places, so please don't change. -->
2508 <!-- ********************************************************** -->
2511 <!-- ~~~~~ New section ~~~~~ -->
2513 <sect3 renderas="sect4" id="add-header">
2514 <title>add-header</title>
2518 <term>Typical use:</term>
2520 <para>Confuse log analysis, custom applications</para>
2525 <term>Effect:</term>
2528 Sends a user defined HTTP header to the web server.
2535 <!-- boolean, parameterized, Multi-value -->
2537 <para>Multi-value.</para>
2542 <term>Parameter:</term>
2545 Any string value is possible. Validity of the defined HTTP headers is not checked.
2546 It is recommended that you use the <quote><literal>X-</literal></quote> prefix
2556 This action may be specified multiple times, in order to define multiple
2557 headers. This is rarely needed for the typical user. If you don't know what
2558 <quote>HTTP headers</quote> are, you definitely don't need to worry about this
2562 Headers added by this action are not modified by other actions.
2568 <term>Example usage:</term>
2571 <screen>+add-header{X-User-Tracking: sucks}</screen>
2579 <!-- ~~~~~ New section ~~~~~ -->
2580 <sect3 renderas="sect4" id="block">
2581 <title>block</title>
2585 <term>Typical use:</term>
2587 <para>Block ads or other unwanted content</para>
2592 <term>Effect:</term>
2595 Requests for URLs to which this action applies are blocked, i.e. the
2596 requests are trapped by &my-app; and the requested URL is never retrieved,
2597 but is answered locally with a substitute page or image, as determined by
2599 linkend="handle-as-image">handle-as-image</link></literal>,
2601 linkend="set-image-blocker">set-image-blocker</link></literal>, and
2603 linkend="handle-as-empty-document">handle-as-empty-document</link></literal> actions.
2611 <!-- boolean, parameterized, Multi-value -->
2613 <para>Parameterized.</para>
2618 <term>Parameter:</term>
2620 <para>A block reason that should be given to the user.</para>
2628 <application>Privoxy</application> sends a special <quote>BLOCKED</quote> page
2629 for requests to blocked pages. This page contains the block reason given as
2630 parameter, a link to find out why the block action applies, and a click-through
2631 to the blocked content (the latter only if the force feature is available and
2635 A very important exception occurs if <emphasis>both</emphasis>
2636 <literal>block</literal> and <literal><link linkend="handle-as-image">handle-as-image</link></literal>,
2637 apply to the same request: it will then be replaced by an image. If
2638 <literal><link linkend="set-image-blocker">set-image-blocker</link></literal>
2639 (see below) also applies, the type of image will be determined by its parameter,
2640 if not, the standard checkerboard pattern is sent.
2643 It is important to understand this process, in order
2644 to understand how <application>Privoxy</application> deals with
2645 ads and other unwanted content. Blocking is a core feature, and one
2646 upon which various other features depend.
2649 The <literal><link linkend="filter">filter</link></literal>
2650 action can perform a very similar task, by <quote>blocking</quote>
2651 banner images and other content through rewriting the relevant URLs in the
2652 document's HTML source, so they don't get requested in the first place.
2653 Note that this is a totally different technique, and it's easy to confuse the two.
2659 <term>Example usage (section):</term>
2662 <screen>{+block{No nasty stuff for you.}}
2663 # Block and replace with "blocked" page
2664 .nasty-stuff.example.com
2666 {+block{Doubleclick banners.} +handle-as-image}
2667 # Block and replace with image
2671 {+block{Layered ads.} +handle-as-empty-document}
2672 # Block and then ignore
2673 adserver.example.net/.*\.js$</screen>
2683 <!-- ~~~~~ New section ~~~~~ -->
2684 <sect3 renderas="sect4" id="change-x-forwarded-for">
2685 <title>change-x-forwarded-for</title>
2689 <term>Typical use:</term>
2691 <para>Improve privacy by not forwarding the source of the request in the HTTP headers.</para>
2696 <term>Effect:</term>
2699 Deletes the <quote>X-Forwarded-For:</quote> HTTP header from the client request,
2707 <!-- Boolean, Parameterized, Multi-value -->
2709 <para>Parameterized.</para>
2714 <term>Parameter:</term>
2718 <para><quote>block</quote> to delete the header.</para>
2722 <quote>add</quote> to create the header (or append
2723 the client's IP address to an already existing one).
2734 It is safe and recommended to use <literal>block</literal>.
2737 Forwarding the source address of the request may make
2738 sense in some multi-user setups but is also a privacy risk.
2743 <term>Example usage:</term>
2746 <screen>+change-x-forwarded-for{block}</screen>
2753 <!-- ~~~~~ New section ~~~~~ -->
2754 <sect3 renderas="sect4" id="client-header-filter">
2755 <title>client-header-filter</title>
2759 <term>Typical use:</term>
2762 Rewrite or remove single client headers.
2768 <term>Effect:</term>
2771 All client headers to which this action applies are filtered on-the-fly through
2772 the specified regular expression based substitutions.
2779 <!-- boolean, parameterized, Multi-value -->
2781 <para>Multi-value.</para>
2786 <term>Parameter:</term>
2789 The name of a client-header filter, as defined in one of the
2790 <link linkend="filter-file">filter files</link>.
2799 Client-header filters are applied to each header on its own, not to
2800 all at once. This makes it easier to diagnose problems, but on the downside
2801 you can't write filters that only change header x if header y's value is z.
2802 You can do that by using tags though.
2805 Client-header filters are executed after the other header actions have finished
2806 and use their output as input.
2809 If the request URI gets changed, &my-app; will detect that and use the new
2810 one. This can be used to rewrite the request destination behind the client's
2811 back, for example to specify a Tor exit relay for certain requests.
2814 Please refer to the <link linkend="filter-file">filter file chapter</link>
2815 to learn which client-header filters are available by default, and how to
2823 <term>Example usage (section):</term>
2827 # Hide Tor exit notation in Host and Referer Headers
2828 {+client-header-filter{hide-tor-exit-notation}}
2839 <!-- ~~~~~ New section ~~~~~ -->
2840 <sect3 renderas="sect4" id="client-header-tagger">
2841 <title>client-header-tagger</title>
2845 <term>Typical use:</term>
2848 Block requests based on their headers.
2854 <term>Effect:</term>
2857 Client headers to which this action applies are filtered on-the-fly through
2858 the specified regular expression based substitutions, the result is used as
2866 <!-- boolean, parameterized, Multi-value -->
2868 <para>Multi-value.</para>
2873 <term>Parameter:</term>
2876 The name of a client-header tagger, as defined in one of the
2877 <link linkend="filter-file">filter files</link>.
2886 Client-header taggers are applied to each header on its own,
2887 and as the header isn't modified, each tagger <quote>sees</quote>
2891 Client-header taggers are the first actions that are executed
2892 and their tags can be used to control every other action.
2898 <term>Example usage (section):</term>
2902 # Tag every request with the User-Agent header
2903 {+client-header-tagger{user-agent}}
2906 # Tagging itself doesn't change the action
2907 # settings, sections with TAG patterns do:
2909 # If it's a download agent, use a different forwarding proxy,
2910 # show the real User-Agent and make sure resume works.
2911 {+forward-override{forward-socks5 10.0.0.2:2222 .} \
2912 -hide-if-modified-since \
2913 -overwrite-last-modified \
2918 TAG:^User-Agent: NetBSD-ftp/
2919 TAG:^User-Agent: Novell ZYPP Installer
2920 TAG:^User-Agent: RPM APT-HTTP/
2921 TAG:^User-Agent: fetch libfetch/
2922 TAG:^User-Agent: Ubuntu APT-HTTP/
2923 TAG:^User-Agent: MPlayer/
2928 # Tag all requests with the Range header set
2929 {+client-header-tagger{range-requests}}
2932 # Disable filtering for the tagged requests.
2934 # With filtering enabled Privoxy would remove the Range headers
2935 # to be able to filter the whole response. The downside is that
2936 # it prevents clients from resuming downloads or skipping over
2937 # parts of multimedia files.
2938 {-filter -deanimate-gifs}
2949 <!-- ~~~~~ New section ~~~~~ -->
2950 <sect3 renderas="sect4" id="content-type-overwrite">
2951 <title>content-type-overwrite</title>
2955 <term>Typical use:</term>
2957 <para>Stop useless download menus from popping up, or change the browser's rendering mode</para>
2962 <term>Effect:</term>
2965 Replaces the <quote>Content-Type:</quote> HTTP server header.
2972 <!-- Boolean, Parameterized, Multi-value -->
2974 <para>Parameterized.</para>
2979 <term>Parameter:</term>
2991 The <quote>Content-Type:</quote> HTTP server header is used by the
2992 browser to decide what to do with the document. The value of this
2993 header can cause the browser to open a download menu instead of
2994 displaying the document by itself, even if the document's format is
2995 supported by the browser.
2998 The declared content type can also affect which rendering mode
2999 the browser chooses. If XHTML is delivered as <quote>text/html</quote>,
3000 many browsers treat it as yet another broken HTML document.
3001 If it is send as <quote>application/xml</quote>, browsers with
3002 XHTML support will only display it, if the syntax is correct.
3005 If you see a web site that proudly uses XHTML buttons, but sets
3006 <quote>Content-Type: text/html</quote>, you can use &my-app;
3007 to overwrite it with <quote>application/xml</quote> and validate
3008 the web master's claim inside your XHTML-supporting browser.
3009 If the syntax is incorrect, the browser will complain loudly.
3012 You can also go the opposite direction: if your browser prints
3013 error messages instead of rendering a document falsely declared
3014 as XHTML, you can overwrite the content type with
3015 <quote>text/html</quote> and have it rendered as broken HTML document.
3018 By default <literal>content-type-overwrite</literal> only replaces
3019 <quote>Content-Type:</quote> headers that look like some kind of text.
3020 If you want to overwrite it unconditionally, you have to combine it with
3021 <literal><link linkend="force-text-mode">force-text-mode</link></literal>.
3022 This limitation exists for a reason, think twice before circumventing it.
3025 Most of the time it's easier to replace this action with a custom
3026 <literal><link linkend="server-header-filter">server-header filter</link></literal>.
3027 It allows you to activate it for every document of a certain site and it will still
3028 only replace the content types you aimed at.
3031 Of course you can apply <literal>content-type-overwrite</literal>
3032 to a whole site and then make URL based exceptions, but it's a lot
3033 more work to get the same precision.
3039 <term>Example usage (sections):</term>
3042 <screen># Check if www.example.net/ really uses valid XHTML
3043 { +content-type-overwrite{application/xml} }
3046 # but leave the content type unmodified if the URL looks like a style sheet
3047 {-content-type-overwrite}
3048 www.example.net/.*\.css$
3049 www.example.net/.*style
3058 <!-- ~~~~~ New section ~~~~~ -->
3059 <sect3 renderas="sect4" id="crunch-client-header">
3063 <title>crunch-client-header</title>
3067 <term>Typical use:</term>
3069 <para>Remove a client header <application>Privoxy</application> has no dedicated action for.</para>
3074 <term>Effect:</term>
3077 Deletes every header sent by the client that contains the string the user supplied as parameter.
3084 <!-- Boolean, Parameterized, Multi-value -->
3086 <para>Parameterized.</para>
3091 <term>Parameter:</term>
3103 This action allows you to block client headers for which no dedicated
3104 <application>Privoxy</application> action exists.
3105 <application>Privoxy</application> will remove every client header that
3106 contains the string you supplied as parameter.
3109 Regular expressions are <emphasis>not supported</emphasis> and you can't
3110 use this action to block different headers in the same request, unless
3111 they contain the same string.
3114 <literal>crunch-client-header</literal> is only meant for quick tests.
3115 If you have to block several different headers, or only want to modify
3116 parts of them, you should use a
3117 <literal><link linkend="client-header-filter">client-header filter</link></literal>.
3121 Don't block any header without understanding the consequences.
3128 <term>Example usage (section):</term>
3131 <screen># Block the non-existent "Privacy-Violation:" client header
3132 { +crunch-client-header{Privacy-Violation:} }
3142 <!-- ~~~~~ New section ~~~~~ -->
3143 <sect3 renderas="sect4" id="crunch-if-none-match">
3144 <title>crunch-if-none-match</title>
3150 <term>Typical use:</term>
3152 <para>Prevent yet another way to track the user's steps between sessions.</para>
3157 <term>Effect:</term>
3160 Deletes the <quote>If-None-Match:</quote> HTTP client header.
3167 <!-- Boolean, Parameterized, Multi-value -->
3169 <para>Boolean.</para>
3174 <term>Parameter:</term>
3186 Removing the <quote>If-None-Match:</quote> HTTP client header
3187 is useful for filter testing, where you want to force a real
3188 reload instead of getting status code <quote>304</quote> which
3189 would cause the browser to use a cached copy of the page.
3192 It is also useful to make sure the header isn't used as a cookie
3193 replacement (unlikely but possible).
3196 Blocking the <quote>If-None-Match:</quote> header shouldn't cause any
3197 caching problems, as long as the <quote>If-Modified-Since:</quote> header
3198 isn't blocked or missing as well.
3201 It is recommended to use this action together with
3202 <literal><link linkend="hide-if-modified-since">hide-if-modified-since</link></literal>
3204 <literal><link linkend="overwrite-last-modified">overwrite-last-modified</link></literal>.
3210 <term>Example usage (section):</term>
3213 <screen># Let the browser revalidate cached documents but don't
3214 # allow the server to use the revalidation headers for user tracking.
3215 {+hide-if-modified-since{-60} \
3216 +overwrite-last-modified{randomize} \
3217 +crunch-if-none-match}
3226 <!-- ~~~~~ New section ~~~~~ -->
3227 <sect3 renderas="sect4" id="crunch-incoming-cookies">
3228 <title>crunch-incoming-cookies</title>
3232 <term>Typical use:</term>
3235 Prevent the web server from setting HTTP cookies on your system
3241 <term>Effect:</term>
3244 Deletes any <quote>Set-Cookie:</quote> HTTP headers from server replies.
3251 <!-- Boolean, Parameterized, Multi-value -->
3253 <para>Boolean.</para>
3258 <term>Parameter:</term>
3270 This action is only concerned with <emphasis>incoming</emphasis> HTTP cookies. For
3271 <emphasis>outgoing</emphasis> HTTP cookies, use
3272 <literal><link linkend="crunch-outgoing-cookies">crunch-outgoing-cookies</link></literal>.
3273 Use <emphasis>both</emphasis> to disable HTTP cookies completely.
3276 It makes <emphasis>no sense at all</emphasis> to use this action in conjunction
3277 with the <literal><link linkend="session-cookies-only">session-cookies-only</link></literal> action,
3278 since it would prevent the session cookies from being set. See also
3279 <literal><link linkend="filter-content-cookies">filter-content-cookies</link></literal>.
3285 <term>Example usage:</term>
3288 <screen>+crunch-incoming-cookies</screen>
3296 <!-- ~~~~~ New section ~~~~~ -->
3297 <sect3 renderas="sect4" id="crunch-server-header">
3298 <title>crunch-server-header</title>
3304 <term>Typical use:</term>
3306 <para>Remove a server header <application>Privoxy</application> has no dedicated action for.</para>
3311 <term>Effect:</term>
3314 Deletes every header sent by the server that contains the string the user supplied as parameter.
3321 <!-- Boolean, Parameterized, Multi-value -->
3323 <para>Parameterized.</para>
3328 <term>Parameter:</term>
3340 This action allows you to block server headers for which no dedicated
3341 <application>Privoxy</application> action exists. <application>Privoxy</application>
3342 will remove every server header that contains the string you supplied as parameter.
3345 Regular expressions are <emphasis>not supported</emphasis> and you can't
3346 use this action to block different headers in the same request, unless
3347 they contain the same string.
3350 <literal>crunch-server-header</literal> is only meant for quick tests.
3351 If you have to block several different headers, or only want to modify
3352 parts of them, you should use a custom
3353 <literal><link linkend="server-header-filter">server-header filter</link></literal>.
3357 Don't block any header without understanding the consequences.
3364 <term>Example usage (section):</term>
3367 <screen># Crunch server headers that try to prevent caching
3368 { +crunch-server-header{no-cache} }
3377 <!-- ~~~~~ New section ~~~~~ -->
3378 <sect3 renderas="sect4" id="crunch-outgoing-cookies">
3379 <title>crunch-outgoing-cookies</title>
3383 <term>Typical use:</term>
3386 Prevent the web server from reading any HTTP cookies from your system
3392 <term>Effect:</term>
3395 Deletes any <quote>Cookie:</quote> HTTP headers from client requests.
3402 <!-- Boolean, Parameterized, Multi-value -->
3404 <para>Boolean.</para>
3409 <term>Parameter:</term>
3421 This action is only concerned with <emphasis>outgoing</emphasis> HTTP cookies. For
3422 <emphasis>incoming</emphasis> HTTP cookies, use
3423 <literal><link linkend="crunch-incoming-cookies">crunch-incoming-cookies</link></literal>.
3424 Use <emphasis>both</emphasis> to disable HTTP cookies completely.
3427 It makes <emphasis>no sense at all</emphasis> to use this action in conjunction
3428 with the <literal><link linkend="session-cookies-only">session-cookies-only</link></literal> action,
3429 since it would prevent the session cookies from being read.
3435 <term>Example usage:</term>
3438 <screen>+crunch-outgoing-cookies</screen>
3447 <!-- ~~~~~ New section ~~~~~ -->
3448 <sect3 renderas="sect4" id="deanimate-gifs">
3449 <title>deanimate-gifs</title>
3453 <term>Typical use:</term>
3455 <para>Stop those annoying, distracting animated GIF images.</para>
3460 <term>Effect:</term>
3463 De-animate GIF animations, i.e. reduce them to their first or last image.
3470 <!-- boolean, parameterized, Multi-value -->
3472 <para>Parameterized.</para>
3477 <term>Parameter:</term>
3480 <quote>last</quote> or <quote>first</quote>
3489 This will also shrink the images considerably (in bytes, not pixels!). If
3490 the option <quote>first</quote> is given, the first frame of the animation
3491 is used as the replacement. If <quote>last</quote> is given, the last
3492 frame of the animation is used instead, which probably makes more sense for
3493 most banner animations, but also has the risk of not showing the entire
3494 last frame (if it is only a delta to an earlier frame).
3497 You can safely use this action with patterns that will also match non-GIF
3498 objects, because no attempt will be made at anything that doesn't look like
3505 <term>Example usage:</term>
3508 <screen>+deanimate-gifs{last}</screen>
3515 <!-- ~~~~~ New section ~~~~~ -->
3516 <sect3 renderas="sect4" id="downgrade-http-version">
3517 <title>downgrade-http-version</title>
3521 <term>Typical use:</term>
3523 <para>Work around (very rare) problems with HTTP/1.1</para>
3528 <term>Effect:</term>
3531 Downgrades HTTP/1.1 client requests and server replies to HTTP/1.0.
3538 <!-- boolean, parameterized, Multi-value -->
3540 <para>Boolean.</para>
3545 <term>Parameter:</term>
3557 This is a left-over from the time when <application>Privoxy</application>
3558 didn't support important HTTP/1.1 features well. It is left here for the
3559 unlikely case that you experience HTTP/1.1-related problems with some server
3563 Note that enabling this action is only a workaround. It should not
3564 be enabled for sites that work without it. While it shouldn't break
3565 any pages, it has an (usually negative) performance impact.
3568 If you come across a site where enabling this action helps, please report it,
3569 so the cause of the problem can be analyzed. If the problem turns out to be
3570 caused by a bug in <application>Privoxy</application> it should be
3571 fixed so the following release works without the work around.
3577 <term>Example usage (section):</term>
3580 <screen>{+downgrade-http-version}
3581 problem-host.example.com</screen>
3589 <!-- ~~~~~ New section ~~~~~ -->
3590 <sect3 renderas="sect4" id="external-filter">
3591 <title>external-filter</title>
3595 <term>Typical use:</term>
3597 <para>Modify content using a programming language of your choice.</para>
3602 <term>Effect:</term>
3605 All instances of text-based type, most notably HTML and JavaScript, to which
3606 this action applies, can be filtered on-the-fly through the specified external
3608 By default plain text documents are exempted from filtering, because web
3609 servers often use the <literal>text/plain</literal> MIME type for all files
3610 whose type they don't know.)
3617 <!-- boolean, parameterized, Multi-value -->
3619 <para>Multi-value.</para>
3624 <term>Parameter:</term>
3627 The name of an external content filter, as defined in the
3628 <link linkend="filter-file">filter file</link>.
3629 External filters can be defined in one or more files as defined by the
3630 <literal><link linkend="filterfile">filterfile</link></literal>
3631 option in the <link linkend="config">config file</link>.
3634 When used in its negative form,
3635 and without parameters, <emphasis>all</emphasis> filtering with external
3636 filters is completely disabled.
3645 External filters are scripts or programs that can modify the content in
3646 case common <literal><link linkend="filter">filters</link></literal>
3647 aren't powerful enough. With the exception that this action doesn't
3648 use pcrs-based filters, the notes in the
3649 <literal><link linkend="filter">filter</link></literal> section apply.
3653 Currently external filters are executed with &my-app;'s privileges.
3654 Only use external filters you understand and trust.
3658 This feature is experimental, the <literal><link
3659 linkend="external-filter-syntax">syntax</link></literal>
3660 may change in the future.
3667 <term>Example usage:</term>
3670 <screen>+external-filter{fancy-filter}</screen>
3677 <!-- ~~~~~ New section ~~~~~ -->
3678 <sect3 renderas="sect4" id="fast-redirects">
3679 <title>fast-redirects</title>
3683 <term>Typical use:</term>
3685 <para>Fool some click-tracking scripts and speed up indirect links.</para>
3690 <term>Effect:</term>
3693 Detects redirection URLs and redirects the browser without contacting
3694 the redirection server first.
3701 <!-- boolean, parameterized, Multi-value -->
3703 <para>Parameterized.</para>
3708 <term>Parameter:</term>
3713 <quote>simple-check</quote> to just search for the string <quote>http://</quote>
3714 to detect redirection URLs.
3719 <quote>check-decoded-url</quote> to decode URLs (if necessary) before searching
3720 for redirection URLs.
3731 Many sites, like yahoo.com, don't just link to other sites. Instead, they
3732 will link to some script on their own servers, giving the destination as a
3733 parameter, which will then redirect you to the final target. URLs
3734 resulting from this scheme typically look like:
3735 <quote>http://www.example.org/click-tracker.cgi?target=http%3a//www.example.net/</quote>.
3738 Sometimes, there are even multiple consecutive redirects encoded in the
3739 URL. These redirections via scripts make your web browsing more traceable,
3740 since the server from which you follow such a link can see where you go
3741 to. Apart from that, valuable bandwidth and time is wasted, while your
3742 browser asks the server for one redirect after the other. Plus, it feeds
3746 This feature is currently not very smart and is scheduled for improvement.
3747 If it is enabled by default, you will have to create some exceptions to
3748 this action. It can lead to failures in several ways:
3751 Not every URLs with other URLs as parameters is evil.
3752 Some sites offer a real service that requires this information to work.
3753 For example a validation service needs to know, which document to validate.
3754 <literal>fast-redirects</literal> assumes that every URL parameter that
3755 looks like another URL is a redirection target, and will always redirect to
3756 the last one. Most of the time the assumption is correct, but if it isn't,
3757 the user gets redirected anyway.
3760 Another failure occurs if the URL contains other parameters after the URL parameter.
3762 <quote>http://www.example.org/?redirect=http%3a//www.example.net/&foo=bar</quote>.
3763 contains the redirection URL <quote>http://www.example.net/</quote>,
3764 followed by another parameter. <literal>fast-redirects</literal> doesn't know that
3765 and will cause a redirect to <quote>http://www.example.net/&foo=bar</quote>.
3766 Depending on the target server configuration, the parameter will be silently ignored
3767 or lead to a <quote>page not found</quote> error. You can prevent this problem by
3768 first using the <literal><link linkend="redirect">redirect</link></literal> action
3769 to remove the last part of the URL, but it requires a little effort.
3772 To detect a redirection URL, <literal>fast-redirects</literal> only
3773 looks for the string <quote>http://</quote>, either in plain text
3774 (invalid but often used) or encoded as <quote>http%3a//</quote>.
3775 Some sites use their own URL encoding scheme, encrypt the address
3776 of the target server or replace it with a database id. In theses cases
3777 <literal>fast-redirects</literal> is fooled and the request reaches the
3778 redirection server where it probably gets logged.
3784 <term>Example usage:</term>
3788 { +fast-redirects{simple-check} }
3791 { +fast-redirects{check-decoded-url} }
3792 another.example.com/testing</screen>
3801 <!-- ~~~~~ New section ~~~~~ -->
3802 <sect3 renderas="sect4" id="filter">
3803 <title>filter</title>
3807 <term>Typical use:</term>
3809 <para>Get rid of HTML and JavaScript annoyances, banner advertisements (by size),
3810 do fun text replacements, add personalized effects, etc.</para>
3815 <term>Effect:</term>
3818 All instances of text-based type, most notably HTML and JavaScript, to which
3819 this action applies, can be filtered on-the-fly through the specified regular
3820 expression based substitutions. (Note: as of version 3.0.3 plain text documents
3821 are exempted from filtering, because web servers often use the
3822 <literal>text/plain</literal> MIME type for all files whose type they don't know.)
3829 <!-- boolean, parameterized, Multi-value -->
3831 <para>Multi-value.</para>
3836 <term>Parameter:</term>
3839 The name of a content filter, as defined in the <link linkend="filter-file">filter file</link>.
3840 Filters can be defined in one or more files as defined by the
3841 <literal><link linkend="filterfile">filterfile</link></literal>
3842 option in the <link linkend="config">config file</link>.
3843 <filename>default.filter</filename> is the collection of filters
3844 supplied by the developers. Locally defined filters should go
3845 in their own file, such as <filename>user.filter</filename>.
3848 When used in its negative form,
3849 and without parameters, <emphasis>all</emphasis> filtering is completely disabled.
3858 For your convenience, there are a number of pre-defined filters available
3859 in the distribution filter file that you can use. See the examples below for
3863 Filtering requires buffering the page content, which may appear to
3864 slow down page rendering since nothing is displayed until all content has
3865 passed the filters. (The total time until the page is completely rendered
3866 doesn't change much, but it may be perceived as slower since the page is
3867 not incrementally displayed.)
3868 This effect will be more noticeable on slower connections.
3871 <quote>Rolling your own</quote>
3872 filters requires a knowledge of
3873 <ulink url="http://en.wikipedia.org/wiki/Regular_expressions"><quote>Regular
3874 Expressions</quote></ulink> and
3875 <ulink url="http://en.wikipedia.org/wiki/Html"><quote>HTML</quote></ulink>.
3876 This is very powerful feature, and potentially very intrusive.
3877 Filters should be used with caution, and where an equivalent
3878 <quote>action</quote> is not available.
3881 The amount of data that can be filtered is limited to the
3882 <literal><link linkend="buffer-limit">buffer-limit</link></literal>
3883 option in the main <link linkend="config">config file</link>. The
3884 default is 4096 KB (4 Megs). Once this limit is exceeded, the buffered
3885 data, and all pending data, is passed through unfiltered.
3888 Inappropriate MIME types, such as zipped files, are not filtered at all.
3889 (Again, only text-based types except plain text). Encrypted SSL data
3890 (from HTTPS servers) cannot be filtered either, since this would violate
3891 the integrity of the secure transaction. In some situations it might
3892 be necessary to protect certain text, like source code, from filtering
3893 by defining appropriate <literal>-filter</literal> exceptions.
3896 Compressed content can't be filtered either, but if &my-app;
3897 is compiled with zlib support and a supported compression algorithm
3898 is used (gzip or deflate), &my-app; can first decompress the content
3902 If you use a &my-app; version without zlib support, but want filtering to work on
3903 as much documents as possible, even those that would normally be sent compressed,
3904 you must use the <literal><link linkend="prevent-compression">prevent-compression</link></literal>
3905 action in conjunction with <literal>filter</literal>.
3908 Content filtering can achieve some of the same effects as the
3909 <literal><link linkend="block">block</link></literal>
3910 action, i.e. it can be used to block ads and banners. But the mechanism
3911 works quite differently. One effective use, is to block ad banners
3912 based on their size (see below), since many of these seem to be somewhat
3916 <link linkend="contact">Feedback</link> with suggestions for new or
3917 improved filters is particularly welcome!
3920 The below list has only the names and a one-line description of each
3921 predefined filter. There are <link linkend="predefined-filters">more
3922 verbose explanations</link> of what these filters do in the <link
3923 linkend="filter-file">filter file chapter</link>.
3929 <term>Example usage (with filters from the distribution <filename>default.filter</filename> file).
3930 See <link linkend="PREDEFINED-FILTERS">the Predefined Filters section</link> for
3931 more explanation on each:</term>
3934 <anchor id="filter-js-annoyances">
3935 <screen>+filter{js-annoyances} # Get rid of particularly annoying JavaScript abuse.</screen>
3938 <anchor id="filter-js-events">
3939 <screen>+filter{js-events} # Kill JavaScript event bindings and timers (Radically destructive! Only for extra nasty sites).</screen>
3942 <anchor id="filter-html-annoyances">
3943 <screen>+filter{html-annoyances} # Get rid of particularly annoying HTML abuse.</screen>
3946 <anchor id="filter-content-cookies">
3947 <screen>+filter{content-cookies} # Kill cookies that come in the HTML or JS content.</screen>
3950 <anchor id="filter-refresh-tags">
3951 <screen>+filter{refresh-tags} # Kill automatic refresh tags if refresh time is larger than 9 seconds.</screen>
3954 <anchor id="filter-unsolicited-popups">
3955 <screen>+filter{unsolicited-popups} # Disable only unsolicited pop-up windows.</screen>
3958 <anchor id="filter-all-popups">
3959 <screen>+filter{all-popups} # Kill all popups in JavaScript and HTML.</screen>
3962 <anchor id="filter-img-reorder">
3963 <screen>+filter{img-reorder} # Reorder attributes in <img> tags to make the banners-by-* filters more effective.</screen>
3966 <anchor id="filter-banners-by-size">
3967 <screen>+filter{banners-by-size} # Kill banners by size.</screen>
3970 <anchor id="filter-banners-by-link">
3971 <screen>+filter{banners-by-link} # Kill banners by their links to known clicktrackers.</screen>
3974 <anchor id="filter-webbugs">
3975 <screen>+filter{webbugs} # Squish WebBugs (1x1 invisible GIFs used for user tracking).</screen>
3978 <anchor id="filter-tiny-textforms">
3979 <screen>+filter{tiny-textforms} # Extend those tiny textareas up to 40x80 and kill the hard wrap.</screen>
3982 <anchor id="filter-jumping-windows">
3983 <screen>+filter{jumping-windows} # Prevent windows from resizing and moving themselves.</screen>
3986 <anchor id="filter-frameset-borders">
3987 <screen>+filter{frameset-borders} # Give frames a border and make them resizable.</screen>
3990 <anchor id="filter-iframes">
3991 <screen>+filter{iframes} # Removes all detected iframes. Should only be enabled for individual sites.</screen>
3994 <anchor id="filter-demoronizer">
3995 <screen>+filter{demoronizer} # Fix MS's non-standard use of standard charsets.</screen>
3998 <anchor id="filter-shockwave-flash">
3999 <screen>+filter{shockwave-flash} # Kill embedded Shockwave Flash objects.</screen>
4002 <anchor id="filter-quicktime-kioskmode">
4003 <screen>+filter{quicktime-kioskmode} # Make Quicktime movies saveable.</screen>
4006 <anchor id="filter-fun">
4007 <screen>+filter{fun} # Text replacements for subversive browsing fun!</screen>
4010 <anchor id="filter-crude-parental">
4011 <screen>+filter{crude-parental} # Crude parental filtering. Note that this filter doesn't work reliably.</screen>
4014 <anchor id="filter-ie-exploits">
4015 <screen>+filter{ie-exploits} # Disable some known Internet Explorer bug exploits.</screen>
4018 <anchor id="filter-site-specifics">
4019 <screen>+filter{site-specifics} # Cure for site-specific problems. Don't apply generally!</screen>
4022 <anchor id="filter-no-ping">
4023 <screen>+filter{no-ping} # Removes non-standard ping attributes in <a> and <area> tags.</screen>
4026 <anchor id="filter-google">
4027 <screen>+filter{google} # CSS-based block for Google text ads. Also removes a width limitation and the toolbar advertisement.</screen>
4030 <anchor id="filter-yahoo">
4031 <screen>+filter{yahoo} # CSS-based block for Yahoo text ads. Also removes a width limitation.</screen>
4034 <anchor id="filter-msn">
4035 <screen>+filter{msn} # CSS-based block for MSN text ads. Also removes tracking URLs and a width limitation.</screen>
4038 <anchor id="filter-blogspot">
4039 <screen>+filter{blogspot} # Cleans up some Blogspot blogs. Read the fine print before using this.</screen>
4047 <!-- ~~~~~ New section ~~~~~ -->
4048 <sect3 renderas="sect4" id="force-text-mode">
4049 <title>force-text-mode</title>
4055 <term>Typical use:</term>
4057 <para>Force <application>Privoxy</application> to treat a document as if it was in some kind of <emphasis>text</emphasis> format. </para>
4062 <term>Effect:</term>
4065 Declares a document as text, even if the <quote>Content-Type:</quote> isn't detected as such.
4072 <!-- Boolean, Parameterized, Multi-value -->
4074 <para>Boolean.</para>
4079 <term>Parameter:</term>
4091 As explained <literal><link linkend="filter">above</link></literal>,
4092 <application>Privoxy</application> tries to only filter files that are
4093 in some kind of text format. The same restrictions apply to
4094 <literal><link linkend="content-type-overwrite">content-type-overwrite</link></literal>.
4095 <literal>force-text-mode</literal> declares a document as text,
4096 without looking at the <quote>Content-Type:</quote> first.
4100 Think twice before activating this action. Filtering binary data
4101 with regular expressions can cause file damage.
4108 <term>Example usage:</term>
4121 <!-- ~~~~~ New section ~~~~~ -->
4122 <sect3 renderas="sect4" id="forward-override">
4123 <title>forward-override</title>
4129 <term>Typical use:</term>
4131 <para>Change the forwarding settings based on User-Agent or request origin</para>
4136 <term>Effect:</term>
4139 Overrules the forward directives in the configuration file.
4146 <!-- Boolean, Parameterized, Multi-value -->
4148 <para>Parameterized.</para>
4153 <term>Parameter:</term>
4157 <para><quote>forward .</quote> to use a direct connection without any additional proxies.</para>
4161 <quote>forward 127.0.0.1:8123</quote> to use the HTTP proxy listening at 127.0.0.1 port 8123.
4166 <quote>forward-socks4a 127.0.0.1:9050 .</quote> to use the socks4a proxy listening at
4167 127.0.0.1 port 9050. Replace <quote>forward-socks4a</quote> with <quote>forward-socks4</quote>
4168 to use a socks4 connection (with local DNS resolution) instead, use <quote>forward-socks5</quote>
4169 for socks5 connections (with remote DNS resolution).
4174 <quote>forward-socks4a 127.0.0.1:9050 proxy.example.org:8000</quote> to use the socks4a proxy
4175 listening at 127.0.0.1 port 9050 to reach the HTTP proxy listening at proxy.example.org port 8000.
4176 Replace <quote>forward-socks4a</quote> with <quote>forward-socks4</quote> to use a socks4 connection
4177 (with local DNS resolution) instead, use <quote>forward-socks5</quote>
4178 for socks5 connections (with remote DNS resolution).
4183 <quote>forward-webserver 127.0.0.1:80</quote> to use the HTTP
4184 server listening at 127.0.0.1 port 80 without adjusting the
4188 This makes it more convenient to use Privoxy to make
4189 existing websites available as onion services as well.
4192 Many websites serve content with hardcoded URLs and
4193 can't be easily adjusted to change the domain based
4194 on the one used by the client.
4197 Putting Privoxy between Tor and the webserver (or an stunnel
4198 that forwards to the webserver) allows to rewrite headers and
4199 content to make client and server happy at the same time.
4202 Using Privoxy for webservers that are only reachable through
4203 onion addresses and whose location is supposed to be secret
4204 is not recommended and should not be necessary anyway.
4215 This action takes parameters similar to the
4216 <link linkend="forwarding">forward</link> directives in the configuration
4217 file, but without the URL pattern. It can be used as replacement, but normally it's only
4218 used in cases where matching based on the request URL isn't sufficient.
4222 Please read the description for the <link linkend="forwarding">forward</link> directives before
4223 using this action. Forwarding to the wrong people will reduce your privacy and increase the
4224 chances of man-in-the-middle attacks.
4227 If the ports are missing or invalid, default values will be used. This might change
4228 in the future and you shouldn't rely on it. Otherwise incorrect syntax causes Privoxy
4229 to exit. Due to design limitations, invalid parameter syntax isn't detected until the
4230 action is used the first time.
4233 Use the <ulink url="http://config.privoxy.org/show-url-info">show-url-info CGI page</ulink>
4234 to verify that your forward settings do what you thought the do.
4241 <term>Example usage:</term>
4245 # Use an ssh tunnel for requests previously tagged as
4246 # <quote>User-Agent: fetch libfetch/2.0</quote> and make sure
4247 # resuming downloads continues to work.
4249 # This way you can continue to use Tor for your normal browsing,
4250 # without overloading the Tor network with your FreeBSD ports updates
4251 # or downloads of bigger files like ISOs.
4253 # Note that HTTP headers are easy to fake and therefore their
4254 # values are as (un)trustworthy as your clients and users.
4255 {+forward-override{forward-socks5 10.0.0.2:2222 .} \
4256 -hide-if-modified-since \
4257 -overwrite-last-modified \
4259 TAG:^User-Agent: fetch libfetch/2\.0$
4268 <!-- ~~~~~ New section ~~~~~ -->
4269 <sect3 renderas="sect4" id="handle-as-empty-document">
4270 <title>handle-as-empty-document</title>
4276 <term>Typical use:</term>
4278 <para>Mark URLs that should be replaced by empty documents <emphasis>if they get blocked</emphasis></para>
4283 <term>Effect:</term>
4286 This action alone doesn't do anything noticeable. It just marks URLs.
4287 If the <literal><link linkend="block">block</link></literal> action <emphasis>also applies</emphasis>,
4288 the presence or absence of this mark decides whether an HTML <quote>BLOCKED</quote>
4289 page, or an empty document will be sent to the client as a substitute for the blocked content.
4290 The <emphasis>empty</emphasis> document isn't literally empty, but actually contains a single space.
4297 <!-- Boolean, Parameterized, Multi-value -->
4299 <para>Boolean.</para>
4304 <term>Parameter:</term>
4316 Some browsers complain about syntax errors if JavaScript documents
4317 are blocked with <application>Privoxy's</application>
4318 default HTML page; this option can be used to silence them.
4319 And of course this action can also be used to eliminate the &my-app;
4320 BLOCKED message in frames.
4323 The content type for the empty document can be specified with
4324 <literal><link linkend="content-type-overwrite">content-type-overwrite{}</link></literal>,
4325 but usually this isn't necessary.
4331 <term>Example usage:</term>
4334 <screen># Block all documents on example.org that end with ".js",
4335 # but send an empty document instead of the usual HTML message.
4336 {+block{Blocked JavaScript} +handle-as-empty-document}
4346 <!-- ~~~~~ New section ~~~~~ -->
4347 <sect3 renderas="sect4" id="handle-as-image">
4348 <title>handle-as-image</title>
4352 <term>Typical use:</term>
4354 <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>
4359 <term>Effect:</term>
4362 This action alone doesn't do anything noticeable. It just marks URLs as images.
4363 If the <literal><link linkend="block">block</link></literal> action <emphasis>also applies</emphasis>,
4364 the presence or absence of this mark decides whether an HTML <quote>blocked</quote>
4365 page, or a replacement image (as determined by the <literal><link
4366 linkend="set-image-blocker">set-image-blocker</link></literal> action) will be sent to the
4367 client as a substitute for the blocked content.
4374 <!-- Boolean, Parameterized, Multi-value -->
4376 <para>Boolean.</para>
4381 <term>Parameter:</term>
4393 The below generic example section is actually part of <filename>default.action</filename>.
4394 It marks all URLs with well-known image file name extensions as images and should
4398 Users will probably only want to use the handle-as-image action in conjunction with
4399 <literal><link linkend="block">block</link></literal>, to block sources of banners, whose URLs don't
4400 reflect the file type, like in the second example section.
4403 Note that you cannot treat HTML pages as images in most cases. For instance, (in-line) ad
4404 frames require an HTML page to be sent, or they won't display properly.
4405 Forcing <literal>handle-as-image</literal> in this situation will not replace the
4406 ad frame with an image, but lead to error messages.
4412 <term>Example usage (sections):</term>
4415 <screen># Generic image extensions:
4418 /.*\.(gif|jpg|jpeg|png|bmp|ico)$
4420 # These don't look like images, but they're banners and should be
4421 # blocked as images:
4423 {+block{Nasty banners.} +handle-as-image}
4424 nasty-banner-server.example.com/junk.cgi\?output=trash
4433 <!-- ~~~~~ New section ~~~~~ -->
4434 <sect3 renderas="sect4" id="hide-accept-language">
4435 <title>hide-accept-language</title>
4441 <term>Typical use:</term>
4443 <para>Pretend to use different language settings.</para>
4448 <term>Effect:</term>
4451 Deletes or replaces the <quote>Accept-Language:</quote> HTTP header in client requests.
4458 <!-- Boolean, Parameterized, Multi-value -->
4460 <para>Parameterized.</para>
4465 <term>Parameter:</term>
4468 Keyword: <quote>block</quote>, or any user defined value.
4477 Faking the browser's language settings can be useful to make a
4478 foreign User-Agent set with
4479 <literal><link linkend="hide-user-agent">hide-user-agent</link></literal>
4483 However some sites with content in different languages check the
4484 <quote>Accept-Language:</quote> to decide which one to take by default.
4485 Sometimes it isn't possible to later switch to another language without
4486 changing the <quote>Accept-Language:</quote> header first.
4489 Therefore it's a good idea to either only change the
4490 <quote>Accept-Language:</quote> header to languages you understand,
4491 or to languages that aren't wide spread.
4494 Before setting the <quote>Accept-Language:</quote> header
4495 to a rare language, you should consider that it helps to
4496 make your requests unique and thus easier to trace.
4497 If you don't plan to change this header frequently,
4498 you should stick to a common language.
4504 <term>Example usage (section):</term>
4507 <screen># Pretend to use Canadian language settings.
4508 {+hide-accept-language{en-ca} \
4509 +hide-user-agent{Mozilla/5.0 (X11; U; OpenBSD i386; en-CA; rv:1.8.0.4) Gecko/20060628 Firefox/1.5.0.4} \
4519 <!-- ~~~~~ New section ~~~~~ -->
4520 <sect3 renderas="sect4" id="hide-content-disposition">
4521 <title>hide-content-disposition</title>
4527 <term>Typical use:</term>
4529 <para>Prevent download menus for content you prefer to view inside the browser.</para>
4534 <term>Effect:</term>
4537 Deletes or replaces the <quote>Content-Disposition:</quote> HTTP header set by some servers.
4544 <!-- Boolean, Parameterized, Multi-value -->
4546 <para>Parameterized.</para>
4551 <term>Parameter:</term>
4554 Keyword: <quote>block</quote>, or any user defined value.
4563 Some servers set the <quote>Content-Disposition:</quote> HTTP header for
4564 documents they assume you want to save locally before viewing them.
4565 The <quote>Content-Disposition:</quote> header contains the file name
4566 the browser is supposed to use by default.
4569 In most browsers that understand this header, it makes it impossible to
4570 <emphasis>just view</emphasis> the document, without downloading it first,
4571 even if it's just a simple text file or an image.
4574 Removing the <quote>Content-Disposition:</quote> header helps
4575 to prevent this annoyance, but some browsers additionally check the
4576 <quote>Content-Type:</quote> header, before they decide if they can
4577 display a document without saving it first. In these cases, you have
4578 to change this header as well, before the browser stops displaying
4582 It is also possible to change the server's file name suggestion
4583 to another one, but in most cases it isn't worth the time to set
4587 This action will probably be removed in the future,
4588 use server-header filters instead.
4594 <term>Example usage:</term>
4597 <screen># Disarm the download link in Sourceforge's patch tracker
4599 +content-type-overwrite{text/plain}\
4600 +hide-content-disposition{block} }
4601 .sourceforge.net/tracker/download\.php</screen>
4609 <!-- ~~~~~ New section ~~~~~ -->
4610 <sect3 renderas="sect4" id="hide-if-modified-since">
4611 <title>hide-if-modified-since</title>
4617 <term>Typical use:</term>
4619 <para>Prevent yet another way to track the user's steps between sessions.</para>
4624 <term>Effect:</term>
4627 Deletes the <quote>If-Modified-Since:</quote> HTTP client header or modifies its value.
4634 <!-- Boolean, Parameterized, Multi-value -->
4636 <para>Parameterized.</para>
4641 <term>Parameter:</term>
4644 Keyword: <quote>block</quote>, or a user defined value that specifies a range of hours.
4653 Removing this header is useful for filter testing, where you want to force a real
4654 reload instead of getting status code <quote>304</quote>, which would cause the
4655 browser to use a cached copy of the page.
4658 Instead of removing the header, <literal>hide-if-modified-since</literal> can
4659 also add or subtract a random amount of time to/from the header's value.
4660 You specify a range of minutes where the random factor should be chosen from and
4661 <application>Privoxy</application> does the rest. A negative value means
4662 subtracting, a positive value adding.
4665 Randomizing the value of the <quote>If-Modified-Since:</quote> makes
4666 it less likely that the server can use the time as a cookie replacement,
4667 but you will run into caching problems if the random range is too high.
4670 It is a good idea to only use a small negative value and let
4671 <literal><link linkend="overwrite-last-modified">overwrite-last-modified</link></literal>
4672 handle the greater changes.
4675 It is also recommended to use this action together with
4676 <literal><link linkend="crunch-if-none-match">crunch-if-none-match</link></literal>,
4677 otherwise it's more or less pointless.
4683 <term>Example usage (section):</term>
4686 <screen># Let the browser revalidate but make tracking based on the time less likely.
4687 {+hide-if-modified-since{-60} \
4688 +overwrite-last-modified{randomize} \
4689 +crunch-if-none-match}
4698 <!-- ~~~~~ New section ~~~~~ -->
4699 <sect3 renderas="sect4" id="hide-from-header">
4700 <title>hide-from-header</title>
4704 <term>Typical use:</term>
4706 <para>Keep your (old and ill) browser from telling web servers your email address</para>
4711 <term>Effect:</term>
4714 Deletes any existing <quote>From:</quote> HTTP header, or replaces it with the
4722 <!-- Boolean, Parameterized, Multi-value -->
4724 <para>Parameterized.</para>
4729 <term>Parameter:</term>
4732 Keyword: <quote>block</quote>, or any user defined value.
4741 The keyword <quote>block</quote> will completely remove the header
4742 (not to be confused with the <literal><link linkend="block">block</link></literal>
4746 Alternately, you can specify any value you prefer to be sent to the web
4747 server. If you do, it is a matter of fairness not to use any address that
4748 is actually used by a real person.
4751 This action is rarely needed, as modern web browsers don't send
4752 <quote>From:</quote> headers anymore.
4758 <term>Example usage:</term>
4761 <screen>+hide-from-header{block}</screen> or
4762 <screen>+hide-from-header{spam-me-senseless@sittingduck.example.com}</screen>
4770 <!-- ~~~~~ New section ~~~~~ -->
4771 <sect3 renderas="sect4" id="hide-referrer">
4772 <title>hide-referrer</title>
4773 <anchor id="hide-referer">
4776 <term>Typical use:</term>
4778 <para>Conceal which link you followed to get to a particular site</para>
4783 <term>Effect:</term>
4786 Deletes the <quote>Referer:</quote> (sic) HTTP header from the client request,
4787 or replaces it with a forged one.
4794 <!-- Boolean, Parameterized, Multi-value -->
4796 <para>Parameterized.</para>
4801 <term>Parameter:</term>
4805 <para><quote>conditional-block</quote> to delete the header completely if the host has changed.</para>
4808 <para><quote>conditional-forge</quote> to forge the header if the host has changed.</para>
4811 <para><quote>block</quote> to delete the header unconditionally.</para>
4814 <para><quote>forge</quote> to pretend to be coming from the homepage of the server we are talking to.</para>
4817 <para>Any other string to set a user defined referrer.</para>
4827 <literal>conditional-block</literal> is the only parameter,
4828 that isn't easily detected in the server's log file. If it blocks the
4829 referrer, the request will look like the visitor used a bookmark or
4830 typed in the address directly.
4833 Leaving the referrer unmodified for requests on the same host
4834 allows the server owner to see the visitor's <quote>click path</quote>,
4835 but in most cases she could also get that information by comparing
4836 other parts of the log file: for example the User-Agent if it isn't
4837 a very common one, or the user's IP address if it doesn't change between
4841 Always blocking the referrer, or using a custom one, can lead to
4842 failures on servers that check the referrer before they answer any
4843 requests, in an attempt to prevent their content from being
4844 embedded or linked to elsewhere.
4847 Both <literal>conditional-block</literal> and <literal>forge</literal>
4848 will work with referrer checks, as long as content and valid referring page
4849 are on the same host. Most of the time that's the case.
4852 <literal>hide-referer</literal> is an alternate spelling of
4853 <literal>hide-referrer</literal> and the two can be can be freely
4854 substituted with each other. (<quote>referrer</quote> is the
4855 correct English spelling, however the HTTP specification has a bug - it
4856 requires it to be spelled as <quote>referer</quote>.)
4862 <term>Example usage:</term>
4865 <screen>+hide-referrer{forge}</screen> or
4866 <screen>+hide-referrer{http://www.yahoo.com/}</screen>
4874 <!-- ~~~~~ New section ~~~~~ -->
4875 <sect3 renderas="sect4" id="hide-user-agent">
4876 <title>hide-user-agent</title>
4880 <term>Typical use:</term>
4882 <para>Try to conceal your type of browser and client operating system</para>
4887 <term>Effect:</term>
4890 Replaces the value of the <quote>User-Agent:</quote> HTTP header
4891 in client requests with the specified value.
4898 <!-- Boolean, Parameterized, Multi-value -->
4900 <para>Parameterized.</para>
4905 <term>Parameter:</term>
4908 Any user-defined string.
4918 This can lead to problems on web sites that depend on looking at this header in
4919 order to customize their content for different browsers (which, by the
4920 way, is <emphasis>NOT</emphasis> the right thing to do: good web sites
4921 work browser-independently).
4925 Using this action in multi-user setups or wherever different types of
4926 browsers will access the same <application>Privoxy</application> is
4927 <emphasis>not recommended</emphasis>. In single-user, single-browser
4928 setups, you might use it to delete your OS version information from
4929 the headers, because it is an invitation to exploit known bugs for your
4930 OS. It is also occasionally useful to forge this in order to access
4931 sites that won't let you in otherwise (though there may be a good
4932 reason in some cases).
4935 More information on known user-agent strings can be found at
4936 <ulink url="http://www.user-agents.org/">http://www.user-agents.org/</ulink>
4938 <ulink url="http://en.wikipedia.org/wiki/User_agent">http://en.wikipedia.org/wiki/User_agent</ulink>.
4944 <term>Example usage:</term>
4947 <screen>+hide-user-agent{Netscape 6.1 (X11; I; Linux 2.4.18 i686)}</screen>
4955 <!-- ~~~~~ New section ~~~~~ -->
4956 <sect3 renderas="sect4" id="limit-connect">
4957 <title>limit-connect</title>
4961 <term>Typical use:</term>
4963 <para>Prevent abuse of <application>Privoxy</application> as a TCP proxy relay or disable SSL for untrusted sites</para>
4968 <term>Effect:</term>
4971 Specifies to which ports HTTP CONNECT requests are allowable.
4978 <!-- Boolean, Parameterized, Multi-value -->
4980 <para>Parameterized.</para>
4985 <term>Parameter:</term>
4988 A comma-separated list of ports or port ranges (the latter using dashes, with the minimum
4989 defaulting to 0 and the maximum to 65K).
4998 By default, i.e. if no <literal>limit-connect</literal> action applies,
4999 <application>Privoxy</application> allows HTTP CONNECT requests to all
5000 ports. Use <literal>limit-connect</literal> if fine-grained control
5001 is desired for some or all destinations.
5004 The CONNECT methods exists in HTTP to allow access to secure websites
5005 (<quote>https://</quote> URLs) through proxies. It works very simply:
5006 the proxy connects to the server on the specified port, and then
5007 short-circuits its connections to the client and to the remote server.
5008 This means CONNECT-enabled proxies can be used as TCP relays very easily.
5011 <application>Privoxy</application> relays HTTPS traffic without seeing
5012 the decoded content. Websites can leverage this limitation to circumvent &my-app;'s
5013 filters. By specifying an invalid port range you can disable HTTPS entirely.
5019 <term>Example usages:</term>
5021 <!-- I had trouble getting the spacing to look right in my browser -->
5022 <!-- I probably have the wrong font setup, bollocks. -->
5023 <!-- Apparently the emphasis tag uses a proportional font no matter what -->
5025 <screen>+limit-connect{443} # Port 443 is OK.
5026 +limit-connect{80,443} # Ports 80 and 443 are OK.
5027 +limit-connect{-3, 7, 20-100, 500-} # Ports less than 3, 7, 20 to 100 and above 500 are OK.
5028 +limit-connect{-} # All ports are OK
5029 +limit-connect{,} # No HTTPS/SSL traffic is allowed</screen>
5037 <!-- ~~~~~ New section ~~~~~ -->
5038 <sect3 renderas="sect4" id="limit-cookie-lifetime">
5039 <title>limit-cookie-lifetime</title>
5043 <term>Typical use:</term>
5045 <para>Limit the lifetime of HTTP cookies to a couple of minutes or hours.</para>
5050 <term>Effect:</term>
5053 Overwrites the expires field in Set-Cookie server headers if it's above the specified limit.
5060 <!-- Boolean, Parameterized, Multi-value -->
5062 <para>Parameterized.</para>
5067 <term>Parameter:</term>
5070 The lifetime limit in minutes, or 0.
5079 This action reduces the lifetime of HTTP cookies coming from the
5080 server to the specified number of minutes, starting from the time
5081 the cookie passes Privoxy.
5084 Cookies with a lifetime below the limit are not modified.
5085 The lifetime of session cookies is set to the specified limit.
5088 The effect of this action depends on the server.
5091 In case of servers which refresh their cookies with each response
5092 (or at least frequently), the lifetime limit set by this action
5094 Thus, a session associated with the cookie continues to work with
5095 this action enabled, as long as a new request is made before the
5096 last limit set is reached.
5099 However, some servers send their cookies once, with a lifetime of several
5100 years (the year 2037 is a popular choice), and do not refresh them
5101 until a certain event in the future, for example the user logging out.
5102 In this case this action may limit the absolute lifetime of the session,
5103 even if requests are made frequently.
5106 If the parameter is <quote>0</quote>, this action behaves like
5107 <literal><link linkend="session-cookies-only">session-cookies-only</link></literal>.
5113 <term>Example usages:</term>
5116 <screen>+limit-cookie-lifetime{60}
5124 <!-- ~~~~~ New section ~~~~~ -->
5125 <sect3 renderas="sect4" id="prevent-compression">
5126 <title>prevent-compression</title>
5130 <term>Typical use:</term>
5133 Ensure that servers send the content uncompressed, so it can be
5134 passed through <literal><link linkend="filter">filter</link></literal>s.
5140 <term>Effect:</term>
5143 Removes the Accept-Encoding header which can be used to ask for compressed transfer.
5150 <!-- Boolean, Parameterized, Multi-value -->
5152 <para>Boolean.</para>
5157 <term>Parameter:</term>
5169 More and more websites send their content compressed by default, which
5170 is generally a good idea and saves bandwidth. But the <literal><link
5171 linkend="filter">filter</link></literal> and
5172 <literal><link linkend="deanimate-gifs">deanimate-gifs</link></literal>
5173 actions need access to the uncompressed data.
5176 When compiled with zlib support (available since &my-app; 3.0.7), content that should be
5177 filtered is decompressed on-the-fly and you don't have to worry about this action.
5178 If you are using an older &my-app; version, or one that hasn't been compiled with zlib
5179 support, this action can be used to convince the server to send the content uncompressed.
5182 Most text-based instances compress very well, the size is seldom decreased by less than 50%,
5183 for markup-heavy instances like news feeds saving more than 90% of the original size isn't
5187 Not using compression will therefore slow down the transfer, and you should only
5188 enable this action if you really need it. As of &my-app; 3.0.7 it's disabled in all
5189 predefined action settings.
5192 Note that some (rare) ill-configured sites don't handle requests for uncompressed
5193 documents correctly. Broken PHP applications tend to send an empty document body,
5194 some IIS versions only send the beginning of the content. If you enable
5195 <literal>prevent-compression</literal> per default, you might want to add
5196 exceptions for those sites. See the example for how to do that.
5202 <term>Example usage (sections):</term>
5206 # Selectively turn off compression, and enable a filter
5208 { +filter{tiny-textforms} +prevent-compression }
5209 # Match only these sites
5214 # Or instead, we could set a universal default:
5216 { +prevent-compression }
5219 # Then maybe make exceptions for broken sites:
5221 { -prevent-compression }
5222 .compusa.com/</screen>
5231 <!-- ~~~~~ New section ~~~~~ -->
5232 <sect3 renderas="sect4" id="overwrite-last-modified">
5233 <title>overwrite-last-modified</title>
5239 <term>Typical use:</term>
5241 <para>Prevent yet another way to track the user's steps between sessions.</para>
5246 <term>Effect:</term>
5249 Deletes the <quote>Last-Modified:</quote> HTTP server header or modifies its value.
5256 <!-- Boolean, Parameterized, Multi-value -->
5258 <para>Parameterized.</para>
5263 <term>Parameter:</term>
5266 One of the keywords: <quote>block</quote>, <quote>reset-to-request-time</quote>
5267 and <quote>randomize</quote>
5276 Removing the <quote>Last-Modified:</quote> header is useful for filter
5277 testing, where you want to force a real reload instead of getting status
5278 code <quote>304</quote>, which would cause the browser to reuse the old
5279 version of the page.
5282 The <quote>randomize</quote> option overwrites the value of the
5283 <quote>Last-Modified:</quote> header with a randomly chosen time
5284 between the original value and the current time. In theory the server
5285 could send each document with a different <quote>Last-Modified:</quote>
5286 header to track visits without using cookies. <quote>Randomize</quote>
5287 makes it impossible and the browser can still revalidate cached documents.
5290 <quote>reset-to-request-time</quote> overwrites the value of the
5291 <quote>Last-Modified:</quote> header with the current time. You could use
5292 this option together with
5293 <literal><link linkend="hide-if-modified-since">hide-if-modified-since</link></literal>
5294 to further customize your random range.
5297 The preferred parameter here is <quote>randomize</quote>. It is safe
5298 to use, as long as the time settings are more or less correct.
5299 If the server sets the <quote>Last-Modified:</quote> header to the time
5300 of the request, the random range becomes zero and the value stays the same.
5301 Therefore you should later randomize it a second time with
5302 <literal><link linkend="hide-if-modified-since">hided-if-modified-since</link></literal>,
5306 It is also recommended to use this action together with
5307 <literal><link linkend="crunch-if-none-match">crunch-if-none-match</link></literal>.
5313 <term>Example usage:</term>
5316 <screen># Let the browser revalidate without being tracked across sessions
5317 { +hide-if-modified-since{-60} \
5318 +overwrite-last-modified{randomize} \
5319 +crunch-if-none-match}
5328 <!-- ~~~~~ New section ~~~~~ -->
5329 <sect3 renderas="sect4" id="redirect">
5330 <title>redirect</title>
5336 <term>Typical use:</term>
5339 Redirect requests to other sites.
5345 <term>Effect:</term>
5348 Convinces the browser that the requested document has been moved
5349 to another location and the browser should get it from there.
5356 <!-- Boolean, Parameterized, Multi-value -->
5358 <para>Parameterized</para>
5363 <term>Parameter:</term>
5366 An absolute URL or a single pcrs command.
5375 Requests to which this action applies are answered with a
5376 HTTP redirect to URLs of your choosing. The new URL is
5377 either provided as parameter, or derived by applying a
5378 single pcrs command to the original URL.
5381 The syntax for pcrs commands is documented in the
5382 <link linkend="filter-file">filter file</link> section.
5385 Requests can't be blocked and redirected at the same time,
5386 applying this action together with
5387 <literal><link linkend="block">block</link></literal>
5388 is a configuration error. Currently the request is blocked
5389 and an error message logged, the behavior may change in the
5390 future and result in Privoxy rejecting the action file.
5393 This action can be combined with
5394 <literal><link linkend="fast-redirects">fast-redirects{check-decoded-url}</link></literal>
5395 to redirect to a decoded version of a rewritten URL.
5398 Use this action carefully, make sure not to create redirection loops
5399 and be aware that using your own redirects might make it
5400 possible to fingerprint your requests.
5403 In case of problems with your redirects, or simply to watch
5404 them working, enable <link linkend="DEBUG">debug 128</link>.
5410 <term>Example usages:</term>
5413 <screen># Replace example.com's style sheet with another one
5414 { +redirect{http://localhost/css-replacements/example.com.css} }
5415 example.com/stylesheet\.css
5417 # Create a short, easy to remember nickname for a favorite site
5418 # (relies on the browser to accept and forward invalid URLs to &my-app;)
5419 { +redirect{http://www.privoxy.org/user-manual/actions-file.html} }
5422 # Always use the expanded view for Undeadly.org articles
5423 # (Note the $ at the end of the URL pattern to make sure
5424 # the request for the rewritten URL isn't redirected as well)
5425 {+redirect{s@$@&mode=expanded@}}
5426 undeadly.org/cgi\?action=article&sid=\d*$
5428 # Redirect Google search requests to MSN
5429 {+redirect{s@^http://[^/]*/search\?q=([^&]*).*@http://search.msn.com/results.aspx?q=$1@}}
5432 # Redirect MSN search requests to Yahoo
5433 {+redirect{s@^http://[^/]*/results\.aspx\?q=([^&]*).*@http://search.yahoo.com/search?p=$1@}}
5434 search.msn.com//results\.aspx\?q=
5436 # Redirect http://example.com/&bla=fasel&toChange=foo (and any other value but "bar")
5437 # to http://example.com/&bla=fasel&toChange=bar
5439 # The URL pattern makes sure that the following request isn't redirected again.
5440 {+redirect{s@toChange=[^&]+@toChange=bar@}}
5441 example.com/.*toChange=(?!bar)
5443 # Add a shortcut to look up illumos bugs
5444 {+redirect{s@^http://i([0-9]+)/.*@https://www.illumos.org/issues/$1@}}
5445 # Redirected URL = http://i4974/
5446 # Redirect Destination = https://www.illumos.org/issues/4974
5447 i[0-9][0-9][0-9][0-9]*/
5449 # Redirect remote requests for this manual
5450 # to the local version delivered by Privoxy
5451 {+redirect{s@^http://www@http://config@}}
5452 www.privoxy.org/user-manual/</screen>
5461 <!-- ~~~~~ New section ~~~~~ -->
5462 <sect3 renderas="sect4" id="server-header-filter">
5463 <title>server-header-filter</title>
5467 <term>Typical use:</term>
5470 Rewrite or remove single server headers.
5476 <term>Effect:</term>
5479 All server headers to which this action applies are filtered on-the-fly
5480 through the specified regular expression based substitutions.
5487 <!-- boolean, parameterized, Multi-value -->
5489 <para>Multi-value.</para>
5494 <term>Parameter:</term>
5497 The name of a server-header filter, as defined in one of the
5498 <link linkend="filter-file">filter files</link>.
5507 Server-header filters are applied to each header on its own, not to
5508 all at once. This makes it easier to diagnose problems, but on the downside
5509 you can't write filters that only change header x if header y's value is z.
5510 You can do that by using tags though.
5513 Server-header filters are executed after the other header actions have finished
5514 and use their output as input.
5517 Please refer to the <link linkend="filter-file">filter file chapter</link>
5518 to learn which server-header filters are available by default, and how to
5525 <term>Example usage (section):</term>
5529 {+server-header-filter{html-to-xml}}
5530 example.org/xml-instance-that-is-delivered-as-html
5532 {+server-header-filter{xml-to-html}}
5533 example.org/instance-that-is-delivered-as-xml-but-is-not
5543 <!-- ~~~~~ New section ~~~~~ -->
5544 <sect3 renderas="sect4" id="server-header-tagger">
5545 <title>server-header-tagger</title>
5549 <term>Typical use:</term>
5552 Enable or disable filters based on the Content-Type header.
5558 <term>Effect:</term>
5561 Server headers to which this action applies are filtered on-the-fly through
5562 the specified regular expression based substitutions, the result is used as
5570 <!-- boolean, parameterized, Multi-value -->
5572 <para>Multi-value.</para>
5577 <term>Parameter:</term>
5580 The name of a server-header tagger, as defined in one of the
5581 <link linkend="filter-file">filter files</link>.
5590 Server-header taggers are applied to each header on its own,
5591 and as the header isn't modified, each tagger <quote>sees</quote>
5595 Server-header taggers are executed before all other header actions
5596 that modify server headers. Their tags can be used to control
5597 all of the other server-header actions, the content filters
5598 and the crunch actions (<link linkend="redirect">redirect</link>
5599 and <link linkend="block">block</link>).
5602 Obviously crunching based on tags created by server-header taggers
5603 doesn't prevent the request from showing up in the server's log file.
5610 <term>Example usage (section):</term>
5614 # Tag every request with the content type declared by the server
5615 {+server-header-tagger{content-type}}
5618 # If the response has a tag starting with 'image/' enable an external
5619 # filter that only applies to images.
5621 # Note that the filter is not available by default, it's just a
5622 # <literal><link linkend="external-filter-syntax">silly example</link></literal>.
5623 {+external-filter{rotate-image} +force-text-mode}
5634 <!-- ~~~~~ New section ~~~~~ -->
5635 <sect3 renderas="sect4" id="session-cookies-only">
5636 <title>session-cookies-only</title>
5640 <term>Typical use:</term>
5643 Allow only temporary <quote>session</quote> cookies (for the current
5644 browser session <emphasis>only</emphasis>).
5650 <term>Effect:</term>
5653 Deletes the <quote>expires</quote> field from <quote>Set-Cookie:</quote>
5654 server headers. Most browsers will not store such cookies permanently and
5655 forget them in between sessions.
5662 <!-- Boolean, Parameterized, Multi-value -->
5664 <para>Boolean.</para>
5669 <term>Parameter:</term>
5681 This is less strict than <literal><link linkend="crunch-incoming-cookies">crunch-incoming-cookies</link></literal> /
5682 <literal><link linkend="crunch-outgoing-cookies">crunch-outgoing-cookies</link></literal> and allows you to browse
5683 websites that insist or rely on setting cookies, without compromising your privacy too badly.
5686 Most browsers will not permanently store cookies that have been processed by
5687 <literal>session-cookies-only</literal> and will forget about them between sessions.
5688 This makes profiling cookies useless, but won't break sites which require cookies so
5689 that you can log in for transactions. This is generally turned on for all
5690 sites, and is the recommended setting.
5693 It makes <emphasis>no sense at all</emphasis> to use <literal>session-cookies-only</literal>
5694 together with <literal><link linkend="crunch-incoming-cookies">crunch-incoming-cookies</link></literal> or
5695 <literal><link linkend="crunch-outgoing-cookies">crunch-outgoing-cookies</link></literal>. If you do, cookies
5696 will be plainly killed.
5699 Note that it is up to the browser how it handles such cookies without an <quote>expires</quote>
5700 field. If you use an exotic browser, you might want to try it out to be sure.
5703 This setting also has no effect on cookies that may have been stored
5704 previously by the browser before starting <application>Privoxy</application>.
5705 These would have to be removed manually.
5708 <application>Privoxy</application> also uses
5709 the <link linkend="filter-content-cookies">content-cookies filter</link>
5710 to block some types of cookies. Content cookies are not effected by
5711 <literal>session-cookies-only</literal>.
5717 <term>Example usage:</term>
5720 <screen>+session-cookies-only</screen>
5728 <!-- ~~~~~ New section ~~~~~ -->
5729 <sect3 renderas="sect4" id="set-image-blocker">
5730 <title>set-image-blocker</title>
5734 <term>Typical use:</term>
5736 <para>Choose the replacement for blocked images</para>
5741 <term>Effect:</term>
5744 This action alone doesn't do anything noticeable. If <emphasis>both</emphasis>
5745 <literal><link linkend="block">block</link></literal> <emphasis>and</emphasis> <literal><link
5746 linkend="handle-as-image">handle-as-image</link></literal> <emphasis>also</emphasis>
5747 apply, i.e. if the request is to be blocked as an image,
5748 <emphasis>then</emphasis> the parameter of this action decides what will be
5749 sent as a replacement.
5756 <!-- Boolean, Parameterized, Multi-value -->
5758 <para>Parameterized.</para>
5763 <term>Parameter:</term>
5768 <quote>pattern</quote> to send a built-in checkerboard pattern image. The image is visually
5769 decent, scales very well, and makes it obvious where banners were busted.
5774 <quote>blank</quote> to send a built-in transparent image. This makes banners disappear
5775 completely, but makes it hard to detect where <application>Privoxy</application> has blocked
5776 images on a given page and complicates troubleshooting if <application>Privoxy</application>
5777 has blocked innocent images, like navigation icons.
5782 <quote><replaceable class="parameter">target-url</replaceable></quote> to
5783 send a redirect to <replaceable class="parameter">target-url</replaceable>. You can redirect
5784 to any image anywhere, even in your local filesystem via <quote>file:///</quote> URL.
5785 (But note that not all browsers support redirecting to a local file system).
5788 A good application of redirects is to use special <application>Privoxy</application>-built-in
5789 URLs, which send the built-in images, as <replaceable class="parameter">target-url</replaceable>.
5790 This has the same visual effect as specifying <quote>blank</quote> or <quote>pattern</quote> in
5791 the first place, but enables your browser to cache the replacement image, instead of requesting
5792 it over and over again.
5803 The URLs for the built-in images are <quote>http://config.privoxy.org/send-banner?type=<replaceable
5804 class="parameter">type</replaceable></quote>, where <replaceable class="parameter">type</replaceable> is
5805 either <quote>blank</quote> or <quote>pattern</quote>.
5808 There is a third (advanced) type, called <quote>auto</quote>. It is <emphasis>NOT</emphasis> to be
5809 used in <literal>set-image-blocker</literal>, but meant for use from <link linkend="filter-file">filters</link>.
5810 Auto will select the type of image that would have applied to the referring page, had it been an image.
5816 <term>Example usage:</term>
5822 <screen>+set-image-blocker{pattern}</screen>
5825 Redirect to the BSD daemon:
5828 <screen>+set-image-blocker{http://www.freebsd.org/gifs/dae_up3.gif}</screen>
5831 Redirect to the built-in pattern for better caching:
5834 <screen>+set-image-blocker{http://config.privoxy.org/send-banner?type=pattern}</screen>
5842 <!-- ~~~~~ New section ~~~~~ -->
5844 <title>Summary</title>
5846 Note that many of these actions have the potential to cause a page to
5847 misbehave, possibly even not to display at all. There are many ways
5848 a site designer may choose to design his site, and what HTTP header
5849 content, and other criteria, he may depend on. There is no way to have hard
5850 and fast rules for all sites. See the <link
5851 linkend="ACTIONSANAT">Appendix</link> for a brief example on troubleshooting
5857 <!-- ~~~~~ New section ~~~~~ -->
5858 <sect2 id="aliases">
5859 <title>Aliases</title>
5861 Custom <quote>actions</quote>, known to <application>Privoxy</application>
5862 as <quote>aliases</quote>, can be defined by combining other actions.
5863 These can in turn be invoked just like the built-in actions.
5864 Currently, an alias name can contain any character except space, tab,
5866 <quote>{</quote> and <quote>}</quote>, but we <emphasis>strongly
5867 recommend</emphasis> that you only use <quote>a</quote> to <quote>z</quote>,
5868 <quote>0</quote> to <quote>9</quote>, <quote>+</quote>, and <quote>-</quote>.
5869 Alias names are not case sensitive, and are not required to start with a
5870 <quote>+</quote> or <quote>-</quote> sign, since they are merely textually
5874 Aliases can be used throughout the actions file, but they <emphasis>must be
5875 defined in a special section at the top of the file!</emphasis>
5876 And there can only be one such section per actions file. Each actions file may
5877 have its own alias section, and the aliases defined in it are only visible
5881 There are two main reasons to use aliases: One is to save typing for frequently
5882 used combinations of actions, the other one is a gain in flexibility: If you
5883 decide once how you want to handle shops by defining an alias called
5884 <quote>shop</quote>, you can later change your policy on shops in
5885 <emphasis>one</emphasis> place, and your changes will take effect everywhere
5886 in the actions file where the <quote>shop</quote> alias is used. Calling aliases
5887 by their purpose also makes your actions files more readable.
5890 Currently, there is one big drawback to using aliases, though:
5891 <application>Privoxy</application>'s built-in web-based action file
5892 editor honors aliases when reading the actions files, but it expands
5893 them before writing. So the effects of your aliases are of course preserved,
5894 but the aliases themselves are lost when you edit sections that use aliases
5899 Now let's define some aliases...
5904 # Useful custom aliases we can use later.
5906 # Note the (required!) section header line and that this section
5907 # must be at the top of the actions file!
5911 # These aliases just save typing later:
5912 # (Note that some already use other aliases!)
5914 +crunch-all-cookies = +<link linkend="CRUNCH-INCOMING-COOKIES">crunch-incoming-cookies</link> +<link linkend="CRUNCH-OUTGOING-COOKIES">crunch-outgoing-cookies</link>
5915 -crunch-all-cookies = -<link linkend="CRUNCH-INCOMING-COOKIES">crunch-incoming-cookies</link> -<link linkend="CRUNCH-OUTGOING-COOKIES">crunch-outgoing-cookies</link>
5916 +block-as-image = +block{Blocked image.} +handle-as-image
5917 allow-all-cookies = -crunch-all-cookies -<link linkend="SESSION-COOKIES-ONLY">session-cookies-only</link> -<link linkend="FILTER-CONTENT-COOKIES">filter{content-cookies}</link>
5919 # These aliases define combinations of actions
5920 # that are useful for certain types of sites:
5922 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>
5924 shop = -crunch-all-cookies -<link linkend="FILTER-ALL-POPUPS">filter{all-popups}</link>
5926 # Short names for other aliases, for really lazy people ;-)
5928 c0 = +crunch-all-cookies
5929 c1 = -crunch-all-cookies</screen>
5933 ...and put them to use. These sections would appear in the lower part of an
5934 actions file and define exceptions to the default actions (as specified further
5935 up for the <quote>/</quote> pattern):
5940 # These sites are either very complex or very keen on
5941 # user data and require minimal interference to work:
5944 .office.microsoft.com
5945 .windowsupdate.microsoft.com
5946 # Gmail is really mail.google.com, not gmail.com
5950 # Allow cookies (for setting and retrieving your customer data)
5954 .worldpay.com # for quietpc.com
5957 # These shops require pop-ups:
5959 {-filter{all-popups} -filter{unsolicited-popups}}
5961 .overclockers.co.uk</screen>
5965 Aliases like <quote>shop</quote> and <quote>fragile</quote> are typically used for
5966 <quote>problem</quote> sites that require more than one action to be disabled
5967 in order to function properly.
5973 <!-- ~~~~~ New section ~~~~~ -->
5974 <sect2 id="act-examples">
5975 <title>Actions Files Tutorial</title>
5977 The above chapters have shown <link linkend="actions-file">which actions files
5978 there are and how they are organized</link>, how actions are <link
5979 linkend="actions">specified</link> and <link linkend="actions-apply">applied
5980 to URLs</link>, how <link linkend="af-patterns">patterns</link> work, and how to
5981 define and use <link linkend="aliases">aliases</link>. Now, let's look at an
5982 example <filename>match-all.action</filename>, <filename>default.action</filename>
5983 and <filename>user.action</filename> file and see how all these pieces come together:
5987 <title>match-all.action</title>
5989 Remember <emphasis>all actions are disabled when matching starts</emphasis>,
5990 so we have to explicitly enable the ones we want.
5994 While the <filename>match-all.action</filename> file only contains a
5995 single section, it is probably the most important one. It has only one
5996 pattern, <quote><literal>/</literal></quote>, but this pattern
5997 <link linkend="af-patterns">matches all URLs</link>. Therefore, the set of
5998 actions used in this <quote>default</quote> section <emphasis>will
5999 be applied to all requests as a start</emphasis>. It can be partly or
6000 wholly overridden by other actions files like <filename>default.action</filename>
6001 and <filename>user.action</filename>, but it will still be largely responsible
6002 for your overall browsing experience.
6006 Again, at the start of matching, all actions are disabled, so there is
6007 no need to disable any actions here. (Remember: a <quote>+</quote>
6008 preceding the action name enables the action, a <quote>-</quote> disables!).
6009 Also note how this long line has been made more readable by splitting it into
6010 multiple lines with line continuation.
6016 +<link linkend="CHANGE-X-FORWARDED-FOR">change-x-forwarded-for{block}</link> \
6017 +<link linkend="HIDE-FROM-HEADER">hide-from-header{block}</link> \
6018 +<link linkend="SET-IMAGE-BLOCKER">set-image-blocker{pattern}</link> \
6025 The default behavior is now set.
6030 <title>default.action</title>
6033 If you aren't a developer, there's no need for you to edit the
6034 <filename>default.action</filename> file. It is maintained by
6035 the &my-app; developers and if you disagree with some of the
6036 sections, you should overrule them in your <filename>user.action</filename>.
6040 Understanding the <filename>default.action</filename> file can
6041 help you with your <filename>user.action</filename>, though.
6045 The first section in this file is a special section for internal use
6046 that prevents older &my-app; versions from reading the file:
6051 ##########################################################################
6052 # Settings -- Don't change! For internal Privoxy use ONLY.
6053 ##########################################################################
6055 for-privoxy-version=3.0.11</screen>
6059 After that comes the (optional) alias section. We'll use the example
6060 section from the above <link linkend="aliases">chapter on aliases</link>,
6061 that also explains why and how aliases are used:
6066 ##########################################################################
6068 ##########################################################################
6071 # These aliases just save typing later:
6072 # (Note that some already use other aliases!)
6074 +crunch-all-cookies = +<link linkend="CRUNCH-INCOMING-COOKIES">crunch-incoming-cookies</link> +<link linkend="CRUNCH-OUTGOING-COOKIES">crunch-outgoing-cookies</link>
6075 -crunch-all-cookies = -<link linkend="CRUNCH-INCOMING-COOKIES">crunch-incoming-cookies</link> -<link linkend="CRUNCH-OUTGOING-COOKIES">crunch-outgoing-cookies</link>
6076 +block-as-image = +block{Blocked image.} +handle-as-image
6077 mercy-for-cookies = -crunch-all-cookies -<link linkend="SESSION-COOKIES-ONLY">session-cookies-only</link> -<link linkend="FILTER-CONTENT-COOKIES">filter{content-cookies}</link>
6079 # These aliases define combinations of actions
6080 # that are useful for certain types of sites:
6082 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>
6083 shop = -crunch-all-cookies -<link linkend="FILTER-ALL-POPUPS">filter{all-popups}</link></screen>
6087 The first of our specialized sections is concerned with <quote>fragile</quote>
6088 sites, i.e. sites that require minimum interference, because they are either
6089 very complex or very keen on tracking you (and have mechanisms in place that
6090 make them unusable for people who avoid being tracked). We will simply use
6091 our pre-defined <literal>fragile</literal> alias instead of stating the list
6092 of actions explicitly:
6097 ##########################################################################
6098 # Exceptions for sites that'll break under the default action set:
6099 ##########################################################################
6101 # "Fragile" Use a minimum set of actions for these sites (see alias above):
6104 .office.microsoft.com # surprise, surprise!
6105 .windowsupdate.microsoft.com
6106 mail.google.com</screen>
6110 Shopping sites are not as fragile, but they typically
6111 require cookies to log in, and pop-up windows for shopping
6112 carts or item details. Again, we'll use a pre-defined alias:
6121 .worldpay.com # for quietpc.com
6123 .scan.co.uk</screen>
6127 The <literal><link linkend="FAST-REDIRECTS">fast-redirects</link></literal>
6128 action, which may have been enabled in <filename>match-all.action</filename>,
6129 breaks some sites. So disable it for popular sites where we know it misbehaves:
6134 { -<link linkend="FAST-REDIRECTS">fast-redirects</link> }
6138 .altavista.com/.*(like|url|link):http
6139 .altavista.com/trans.*urltext=http
6140 .nytimes.com</screen>
6144 It is important that <application>Privoxy</application> knows which
6145 URLs belong to images, so that <emphasis>if</emphasis> they are to
6146 be blocked, a substitute image can be sent, rather than an HTML page.
6147 Contacting the remote site to find out is not an option, since it
6148 would destroy the loading time advantage of banner blocking, and it
6149 would feed the advertisers information about you. We can mark any
6150 URL as an image with the <literal><link
6151 linkend="handle-as-image">handle-as-image</link></literal> action,
6152 and marking all URLs that end in a known image file extension is a
6158 ##########################################################################
6160 ##########################################################################
6162 # Define which file types will be treated as images, in case they get
6163 # blocked further down this file:
6165 { +<link linkend="HANDLE-AS-IMAGE">handle-as-image</link> }
6166 /.*\.(gif|jpe?g|png|bmp|ico)$</screen>
6170 And then there are known banner sources. They often use scripts to
6171 generate the banners, so it won't be visible from the URL that the
6172 request is for an image. Hence we block them <emphasis>and</emphasis>
6173 mark them as images in one go, with the help of our
6174 <literal>+block-as-image</literal> alias defined above. (We could of
6175 course just as well use <literal>+<link linkend="block">block</link>
6176 +<link linkend="handle-as-image">handle-as-image</link></literal> here.)
6177 Remember that the type of the replacement image is chosen by the
6178 <literal><link linkend="set-image-blocker">set-image-blocker</link></literal>
6179 action. Since all URLs have matched the default section with its
6180 <literal>+<link linkend="set-image-blocker">set-image-blocker</link>{pattern}</literal>
6181 action before, it still applies and needn't be repeated:
6186 # Known ad generators:
6191 .ad.*.doubleclick.net
6192 .a.yimg.com/(?:(?!/i/).)*$
6193 .a[0-9].yimg.com/(?:(?!/i/).)*$
6199 One of the most important jobs of <application>Privoxy</application>
6200 is to block banners. Many of these can be <quote>blocked</quote>
6201 by the <literal><link linkend="filter">filter</link>{banners-by-size}</literal>
6202 action, which we enabled above, and which deletes the references to banner
6203 images from the pages while they are loaded, so the browser doesn't request
6204 them anymore, and hence they don't need to be blocked here. But this naturally
6205 doesn't catch all banners, and some people choose not to use filters, so we
6206 need a comprehensive list of patterns for banner URLs here, and apply the
6207 <literal><link linkend="block">block</link></literal> action to them.
6210 First comes many generic patterns, which do most of the work, by
6211 matching typical domain and path name components of banners. Then comes
6212 a list of individual patterns for specific sites, which is omitted here
6213 to keep the example short:
6218 ##########################################################################
6219 # Block these fine banners:
6220 ##########################################################################
6221 { <link linkend="BLOCK">+block{Banner ads.}</link> }
6229 /.*count(er)?\.(pl|cgi|exe|dll|asp|php[34]?)
6230 /(?:.*/)?(publicite|werbung|rekla(ma|me|am)|annonse|maino(kset|nta|s)?)/
6232 # Site-specific patterns (abbreviated):
6234 .hitbox.com</screen>
6238 It's quite remarkable how many advertisers actually call their banner
6239 servers ads.<replaceable>company</replaceable>.com, or call the directory
6240 in which the banners are stored simply <quote>banners</quote>. So the above
6241 generic patterns are surprisingly effective.
6244 But being very generic, they necessarily also catch URLs that we don't want
6245 to block. The pattern <literal>.*ads.</literal> e.g. catches
6246 <quote>nasty-<emphasis>ads</emphasis>.nasty-corp.com</quote> as intended,
6247 but also <quote>downlo<emphasis>ads</emphasis>.sourcefroge.net</quote> or
6248 <quote><emphasis>ads</emphasis>l.some-provider.net.</quote> So here come some
6249 well-known exceptions to the <literal>+<link linkend="BLOCK">block</link></literal>
6253 Note that these are exceptions to exceptions from the default! Consider the URL
6254 <quote>downloads.sourcefroge.net</quote>: Initially, all actions are deactivated,
6255 so it wouldn't get blocked. Then comes the defaults section, which matches the
6256 URL, but just deactivates the <literal><link linkend="BLOCK">block</link></literal>
6257 action once again. Then it matches <literal>.*ads.</literal>, an exception to the
6258 general non-blocking policy, and suddenly
6259 <literal><link linkend="BLOCK">+block</link></literal> applies. And now, it'll match
6260 <literal>.*loads.</literal>, where <literal><link linkend="BLOCK">-block</link></literal>
6261 applies, so (unless it matches <emphasis>again</emphasis> further down) it ends up
6262 with no <literal><link linkend="BLOCK">block</link></literal> action applying.
6267 ##########################################################################
6268 # Save some innocent victims of the above generic block patterns:
6269 ##########################################################################
6273 { -<link linkend="BLOCK">block</link> }
6274 adv[io]*. # (for advogato.org and advice.*)
6275 adsl. # (has nothing to do with ads)
6276 adobe. # (has nothing to do with ads either)
6277 ad[ud]*. # (adult.* and add.*)
6278 .edu # (universities don't host banners (yet!))
6279 .*loads. # (downloads, uploads etc)
6287 www.globalintersec.com/adv # (adv = advanced)
6288 www.ugu.com/sui/ugu/adv</screen>
6292 Filtering source code can have nasty side effects,
6293 so make an exception for our friends at sourceforge.net,
6294 and all paths with <quote>cvs</quote> in them. Note that
6295 <literal>-<link linkend="FILTER">filter</link></literal>
6296 disables <emphasis>all</emphasis> filters in one fell swoop!
6301 # Don't filter code!
6303 { -<link linkend="FILTER">filter</link> }
6308 .sourceforge.net</screen>
6312 The actual <filename>default.action</filename> is of course much more
6313 comprehensive, but we hope this example made clear how it works.
6318 <sect3><title>user.action</title>
6321 So far we are painting with a broad brush by setting general policies,
6322 which would be a reasonable starting point for many people. Now,
6323 you might want to be more specific and have customized rules that
6324 are more suitable to your personal habits and preferences. These would
6325 be for narrowly defined situations like your ISP or your bank, and should
6326 be placed in <filename>user.action</filename>, which is parsed after all other
6327 actions files and hence has the last word, over-riding any previously
6328 defined actions. <filename>user.action</filename> is also a
6329 <emphasis>safe</emphasis> place for your personal settings, since
6330 <filename>default.action</filename> is actively maintained by the
6331 <application>Privoxy</application> developers and you'll probably want
6332 to install updated versions from time to time.
6336 So let's look at a few examples of things that one might typically do in
6337 <filename>user.action</filename>:
6341 <!-- brief sample user.action here -->
6345 # My user.action file. <fred@example.com></screen>
6349 As <link linkend="aliases">aliases</link> are local to the actions
6350 file that they are defined in, you can't use the ones from
6351 <filename>default.action</filename>, unless you repeat them here:
6356 # Aliases are local to the file they are defined in.
6357 # (Re-)define aliases for this file:
6361 # These aliases just save typing later, and the alias names should
6362 # be self explanatory.
6364 +crunch-all-cookies = +crunch-incoming-cookies +crunch-outgoing-cookies
6365 -crunch-all-cookies = -crunch-incoming-cookies -crunch-outgoing-cookies
6366 allow-all-cookies = -crunch-all-cookies -session-cookies-only
6367 allow-popups = -filter{all-popups}
6368 +block-as-image = +block{Blocked as image.} +handle-as-image
6369 -block-as-image = -block
6371 # These aliases define combinations of actions that are useful for
6372 # certain types of sites:
6374 fragile = -block -crunch-all-cookies -filter -fast-redirects -hide-referrer
6375 shop = -crunch-all-cookies allow-popups
6377 # Allow ads for selected useful free sites:
6379 allow-ads = -block -filter{banners-by-size} -filter{banners-by-link}
6381 # Alias for specific file types that are text, but might have conflicting
6382 # MIME types. We want the browser to force these to be text documents.
6383 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>
6388 Say you have accounts on some sites that you visit regularly, and
6389 you don't want to have to log in manually each time. So you'd like
6390 to allow persistent cookies for these sites. The
6391 <literal>allow-all-cookies</literal> alias defined above does exactly
6392 that, i.e. it disables crunching of cookies in any direction, and the
6393 processing of cookies to make them only temporary.
6398 { allow-all-cookies }
6402 .redhat.com</screen>
6406 Your bank is allergic to some filter, but you don't know which, so you disable them all:
6411 { -<link linkend="FILTER">filter</link> }
6412 .your-home-banking-site.com</screen>
6416 Some file types you may not want to filter for various reasons:
6421 # Technical documentation is likely to contain strings that might
6422 # erroneously get altered by the JavaScript-oriented filters:
6427 # And this stupid host sends streaming video with a wrong MIME type,
6428 # so that Privoxy thinks it is getting HTML and starts filtering:
6430 stupid-server.example.com/</screen>
6434 Example of a simple <link linkend="BLOCK">block</link> action. Say you've
6435 seen an ad on your favourite page on example.com that you want to get rid of.
6436 You have right-clicked the image, selected <quote>copy image location</quote>
6437 and pasted the URL below while removing the leading http://, into a
6438 <literal>{ +block{} }</literal> section. Note that <literal>{ +handle-as-image
6439 }</literal> need not be specified, since all URLs ending in
6440 <literal>.gif</literal> will be tagged as images by the general rules as set
6441 in default.action anyway:
6446 { +<link linkend="BLOCK">block</link>{Nasty ads.} }
6447 www.example.com/nasty-ads/sponsor\.gif
6448 another.example.net/more/junk/here/</screen>
6452 The URLs of dynamically generated banners, especially from large banner
6453 farms, often don't use the well-known image file name extensions, which
6454 makes it impossible for <application>Privoxy</application> to guess
6455 the file type just by looking at the URL.
6456 You can use the <literal>+block-as-image</literal> alias defined above for
6458 Note that objects which match this rule but then turn out NOT to be an
6459 image are typically rendered as a <quote>broken image</quote> icon by the
6460 browser. Use cautiously.
6469 ar.atwola.com/</screen>
6473 Now you noticed that the default configuration breaks Forbes Magazine,
6474 but you were too lazy to find out which action is the culprit, and you
6475 were again too lazy to give <link linkend="contact">feedback</link>, so
6476 you just used the <literal>fragile</literal> alias on the site, and
6477 -- <emphasis>whoa!</emphasis> -- it worked. The <literal>fragile</literal>
6478 aliases disables those actions that are most likely to break a site. Also,
6479 good for testing purposes to see if it is <application>Privoxy</application>
6480 that is causing the problem or not. We later find other regular sites
6481 that misbehave, and add those to our personalized list of troublemakers:
6489 .mybank.com</screen>
6493 You like the <quote>fun</quote> text replacements in <filename>default.filter</filename>,
6494 but it is disabled in the distributed actions file.
6495 So you'd like to turn it on in your private,
6496 update-safe config, once and for all:
6501 { +<link linkend="filter-fun">filter{fun}</link> }
6502 / # For ALL sites!</screen>
6506 Note that the above is not really a good idea: There are exceptions
6507 to the filters in <filename>default.action</filename> for things that
6508 really shouldn't be filtered, like code on CVS->Web interfaces. Since
6509 <filename>user.action</filename> has the last word, these exceptions
6510 won't be valid for the <quote>fun</quote> filtering specified here.
6514 You might also worry about how your favourite free websites are
6515 funded, and find that they rely on displaying banner advertisements
6516 to survive. So you might want to specifically allow banners for those
6517 sites that you feel provide value to you:
6529 Note that <literal>allow-ads</literal> has been aliased to
6530 <literal>-<link linkend="block">block</link></literal>,
6531 <literal>-<link linkend="filter-banners-by-size">filter{banners-by-size}</link></literal>, and
6532 <literal>-<link linkend="filter-banners-by-link">filter{banners-by-link}</link></literal> above.
6536 Invoke another alias here to force an over-ride of the MIME type <literal>
6537 application/x-sh</literal> which typically would open a download type
6538 dialog. In my case, I want to look at the shell script, and then I can save
6539 it should I choose to.
6549 <filename>user.action</filename> is generally the best place to define
6550 exceptions and additions to the default policies of
6551 <filename>default.action</filename>. Some actions are safe to have their
6552 default policies set here though. So let's set a default policy to have a
6553 <quote>blank</quote> image as opposed to the checkerboard pattern for
6554 <emphasis>ALL</emphasis> sites. <quote>/</quote> of course matches all URL
6560 { +<link linkend="set-image-blocker">set-image-blocker{blank}</link> }
6561 / # ALL sites</screen>
6567 <!-- ~ End section ~ -->
6571 <!-- ~ End section ~ -->
6573 <!-- ~~~~~~~~ New section Header ~~~~~~~~~ -->
6575 <sect1 id="filter-file">
6576 <title>Filter Files</title>
6579 On-the-fly text substitutions need
6580 to be defined in a <quote>filter file</quote>. Once defined, they
6581 can then be invoked as an <quote>action</quote>.
6585 &my-app; supports three different pcrs-based filter actions:
6586 <literal><link linkend="filter">filter</link></literal> to
6587 rewrite the content that is send to the client,
6588 <literal><link linkend="client-header-filter">client-header-filter</link></literal>
6589 to rewrite headers that are send by the client, and
6590 <literal><link linkend="server-header-filter">server-header-filter</link></literal>
6591 to rewrite headers that are send by the server.
6595 &my-app; also supports two tagger actions:
6596 <literal><link linkend="client-header-tagger">client-header-tagger</link></literal>
6598 <literal><link linkend="server-header-tagger">server-header-tagger</link></literal>.
6599 Taggers and filters use the same syntax in the filter files, the difference
6600 is that taggers don't modify the text they are filtering, but use a rewritten
6601 version of the filtered text as tag. The tags can then be used to change the
6602 applying actions through sections with <link linkend="tag-pattern">tag-patterns</link>.
6606 Finally &my-app; supports the
6607 <literal><link linkend="external-filter">external-filter</link></literal> action
6608 to enable <literal><link linkend="external-filter-syntax">external filters</link></literal>
6609 written in proper programming languages.
6614 Multiple filter files can be defined through the <literal> <link
6615 linkend="filterfile">filterfile</link></literal> config directive. The filters
6616 as supplied by the developers are located in
6617 <filename>default.filter</filename>. It is recommended that any locally
6618 defined or modified filters go in a separately defined file such as
6619 <filename>user.filter</filename>.
6623 Common tasks for content filters are to eliminate common annoyances in
6624 HTML and JavaScript, such as pop-up windows,
6625 exit consoles, crippled windows without navigation tools, the
6626 infamous <BLINK> tag etc, to suppress images with certain
6627 width and height attributes (standard banner sizes or web-bugs),
6628 or just to have fun.
6632 Enabled content filters are applied to any content whose
6633 <quote>Content Type</quote> header is recognised as a sign
6634 of text-based content, with the exception of <literal>text/plain</literal>.
6635 Use the <link linkend="FORCE-TEXT-MODE">force-text-mode</link> action
6636 to also filter other content.
6640 Substitutions are made at the source level, so if you want to <quote>roll
6641 your own</quote> filters, you should first be familiar with HTML syntax,
6642 and, of course, regular expressions.
6646 Just like the <link linkend="actions-file">actions files</link>, the
6647 filter file is organized in sections, which are called <emphasis>filters</emphasis>
6648 here. Each filter consists of a heading line, that starts with one of the
6649 <emphasis>keywords</emphasis> <literal>FILTER:</literal>,
6650 <literal>CLIENT-HEADER-FILTER:</literal> or <literal>SERVER-HEADER-FILTER:</literal>
6651 followed by the filter's <emphasis>name</emphasis>, and a short (one line)
6652 <emphasis>description</emphasis> of what it does. Below that line
6653 come the <emphasis>jobs</emphasis>, i.e. lines that define the actual
6654 text substitutions. By convention, the name of a filter
6655 should describe what the filter <emphasis>eliminates</emphasis>. The
6656 comment is used in the <ulink url="http://config.privoxy.org/">web-based
6657 user interface</ulink>.
6661 Once a filter called <replaceable>name</replaceable> has been defined
6662 in the filter file, it can be invoked by using an action of the form
6663 +<literal><link linkend="filter">filter</link>{<replaceable>name</replaceable>}</literal>
6664 in any <link linkend="actions-file">actions file</link>.
6668 Filter definitions start with a header line that contains the filter
6669 type, the filter name and the filter description.
6670 A content filter header line for a filter called <quote>foo</quote> could look
6675 <screen>FILTER: foo Replace all "foo" with "bar"</screen>
6679 Below that line, and up to the next header line, come the jobs that
6680 define what text replacements the filter executes. They are specified
6681 in a syntax that imitates <ulink url="http://www.perl.org/">Perl</ulink>'s
6682 <literal>s///</literal> operator. If you are familiar with Perl, you
6683 will find this to be quite intuitive, and may want to look at the
6684 PCRS documentation for the subtle differences to Perl behaviour.
6688 Most notably, the non-standard option letter <literal>U</literal> is supported,
6689 which turns the default to ungreedy matching (add <literal>?</literal> to
6690 quantifiers to turn them greedy again).
6694 The non-standard option letter <literal>D</literal> (dynamic) allows
6695 to use the variables $host, $origin (the IP address the request came from),
6696 $path and $url. They will be replaced with the value they refer to before
6697 the filter is executed.
6701 Note that '$' is a bad choice for a delimiter in a dynamic filter as you
6702 might end up with unintended variables if you use a variable name
6703 directly after the delimiter. Variables will be resolved without
6704 escaping anything, therefore you also have to be careful not to chose
6705 delimiters that appear in the replacement text. For example '<' should
6706 be save, while '?' will sooner or later cause conflicts with $url.
6710 The non-standard option letter <literal>T</literal> (trivial) prevents
6711 parsing for backreferences in the substitute. Use it if you want to include
6712 text like '$&' in your substitute without quoting.
6717 <ulink url="http://en.wikipedia.org/wiki/Regular_expressions"><quote>Regular
6718 Expressions</quote></ulink>, you might want to take a look at
6719 the <link linkend="regex">Appendix on regular expressions</link>, and
6720 see the <ulink url="http://perldoc.perl.org/perlre.html">Perl
6722 <ulink url="http://perldoc.perl.org/perlop.html">the
6723 <literal>s///</literal> operator's syntax</ulink> and <ulink
6724 url="http://perldoc.perl.org/perlre.html">Perl-style regular
6725 expressions</ulink> in general.
6726 The below examples might also help to get you started.
6730 <!-- ~~~~~~~~ New section Header ~~~~~~~~~ -->
6732 <sect2><title>Filter File Tutorial</title>
6734 Now, let's complete our <quote>foo</quote> content filter. We have already defined
6735 the heading, but the jobs are still missing. Since all it does is to replace
6736 <quote>foo</quote> with <quote>bar</quote>, there is only one (trivial) job
6741 <screen>s/foo/bar/</screen>
6745 But wait! Didn't the comment say that <emphasis>all</emphasis> occurrences
6746 of <quote>foo</quote> should be replaced? Our current job will only take
6747 care of the first <quote>foo</quote> on each page. For global substitution,
6748 we'll need to add the <literal>g</literal> option:
6752 <screen>s/foo/bar/g</screen>
6756 Our complete filter now looks like this:
6759 <screen>FILTER: foo Replace all "foo" with "bar"
6760 s/foo/bar/g</screen>
6764 Let's look at some real filters for more interesting examples. Here you see
6765 a filter that protects against some common annoyances that arise from JavaScript
6766 abuse. Let's look at its jobs one after the other:
6772 FILTER: js-annoyances Get rid of particularly annoying JavaScript abuse
6774 # Get rid of JavaScript referrer tracking. Test page: http://www.randomoddness.com/untitled.htm
6776 s|(<script.*)document\.referrer(.*</script>)|$1"Not Your Business!"$2|Usg</screen>
6780 Following the header line and a comment, you see the job. Note that it uses
6781 <literal>|</literal> as the delimiter instead of <literal>/</literal>, because
6782 the pattern contains a forward slash, which would otherwise have to be escaped
6783 by a backslash (<literal>\</literal>).
6787 Now, let's examine the pattern: it starts with the text <literal><script.*</literal>
6788 enclosed in parentheses. Since the dot matches any character, and <literal>*</literal>
6789 means: <quote>Match an arbitrary number of the element left of myself</quote>, this
6790 matches <quote><script</quote>, followed by <emphasis>any</emphasis> text, i.e.
6791 it matches the whole page, from the start of the first <script> tag.
6795 That's more than we want, but the pattern continues: <literal>document\.referrer</literal>
6796 matches only the exact string <quote>document.referrer</quote>. The dot needed to
6797 be <emphasis>escaped</emphasis>, i.e. preceded by a backslash, to take away its
6798 special meaning as a joker, and make it just a regular dot. So far, the meaning is:
6799 Match from the start of the first <script> tag in a the page, up to, and including,
6800 the text <quote>document.referrer</quote>, if <emphasis>both</emphasis> are present
6801 in the page (and appear in that order).
6805 But there's still more pattern to go. The next element, again enclosed in parentheses,
6806 is <literal>.*</script></literal>. You already know what <literal>.*</literal>
6807 means, so the whole pattern translates to: Match from the start of the first <script>
6808 tag in a page to the end of the last <script> tag, provided that the text
6809 <quote>document.referrer</quote> appears somewhere in between.
6813 This is still not the whole story, since we have ignored the options and the parentheses:
6814 The portions of the page matched by sub-patterns that are enclosed in parentheses, will be
6815 remembered and be available through the variables <literal>$1, $2, ...</literal> in
6816 the substitute. The <literal>U</literal> option switches to ungreedy matching, which means
6817 that the first <literal>.*</literal> in the pattern will only <quote>eat up</quote> all
6818 text in between <quote><script</quote> and the <emphasis>first</emphasis> occurrence
6819 of <quote>document.referrer</quote>, and that the second <literal>.*</literal> will
6820 only span the text up to the <emphasis>first</emphasis> <quote></script></quote>
6821 tag. Furthermore, the <literal>s</literal> option says that the match may span
6822 multiple lines in the page, and the <literal>g</literal> option again means that the
6823 substitution is global.
6827 So, to summarize, the pattern means: Match all scripts that contain the text
6828 <quote>document.referrer</quote>. Remember the parts of the script from
6829 (and including) the start tag up to (and excluding) the string
6830 <quote>document.referrer</quote> as <literal>$1</literal>, and the part following
6831 that string, up to and including the closing tag, as <literal>$2</literal>.
6835 Now the pattern is deciphered, but wasn't this about substituting things? So
6836 lets look at the substitute: <literal>$1"Not Your Business!"$2</literal> is
6837 easy to read: The text remembered as <literal>$1</literal>, followed by
6838 <literal>"Not Your Business!"</literal> (<emphasis>including</emphasis>
6839 the quotation marks!), followed by the text remembered as <literal>$2</literal>.
6840 This produces an exact copy of the original string, with the middle part
6841 (the <quote>document.referrer</quote>) replaced by <literal>"Not Your
6842 Business!"</literal>.
6846 The whole job now reads: Replace <quote>document.referrer</quote> by
6847 <literal>"Not Your Business!"</literal> wherever it appears inside a
6848 <script> tag. Note that this job won't break JavaScript syntax,
6849 since both the original and the replacement are syntactically valid
6850 string objects. The script just won't have access to the referrer
6851 information anymore.
6855 We'll show you two other jobs from the JavaScript taming department, but
6856 this time only point out the constructs of special interest:
6861 # The status bar is for displaying link targets, not pointless blahblah
6863 s/window\.status\s*=\s*(['"]).*?\1/dUmMy=1/ig</screen>
6867 <literal>\s</literal> stands for whitespace characters (space, tab, newline,
6868 carriage return, form feed), so that <literal>\s*</literal> means: <quote>zero
6869 or more whitespace</quote>. The <literal>?</literal> in <literal>.*?</literal>
6870 makes this matching of arbitrary text ungreedy. (Note that the <literal>U</literal>
6871 option is not set). The <literal>['"]</literal> construct means: <quote>a single
6872 <emphasis>or</emphasis> a double quote</quote>. Finally, <literal>\1</literal> is
6873 a back-reference to the first parenthesis just like <literal>$1</literal> above,
6874 with the difference that in the <emphasis>pattern</emphasis>, a backslash indicates
6875 a back-reference, whereas in the <emphasis>substitute</emphasis>, it's the dollar.
6879 So what does this job do? It replaces assignments of single- or double-quoted
6880 strings to the <quote>window.status</quote> object with a dummy assignment
6881 (using a variable name that is hopefully odd enough not to conflict with
6882 real variables in scripts). Thus, it catches many cases where e.g. pointless
6883 descriptions are displayed in the status bar instead of the link target when
6884 you move your mouse over links.
6889 # Kill OnUnload popups. Yummy. Test: http://www.zdnet.com/zdsubs/yahoo/tree/yfs.html
6891 s/(<body [^>]*)onunload(.*>)/$1never$2/iU</screen>
6896 <ulink url="http://www.w3.org/TR/2000/REC-DOM-Level-2-Events-20001113/events.html#Events-eventgroupings-htmlevents">OnUnload
6897 event binding</ulink> in the HTML DOM was a <emphasis>CRIME</emphasis>.
6898 When I close a browser window, I want it to close and die. Basta.
6899 This job replaces the <quote>onunload</quote> attribute in
6900 <quote><body></quote> tags with the dummy word <literal>never</literal>.
6901 Note that the <literal>i</literal> option makes the pattern matching
6902 case-insensitive. Also note that ungreedy matching alone doesn't always guarantee
6903 a minimal match: In the first parenthesis, we had to use <literal>[^>]*</literal>
6904 instead of <literal>.*</literal> to prevent the match from exceeding the
6905 <body> tag if it doesn't contain <quote>OnUnload</quote>, but the page's
6910 The last example is from the fun department:
6915 FILTER: fun Fun text replacements
6917 # Spice the daily news:
6919 s/microsoft(?!\.com)/MicroSuck/ig</screen>
6923 Note the <literal>(?!\.com)</literal> part (a so-called negative lookahead)
6924 in the job's pattern, which means: Don't match, if the string
6925 <quote>.com</quote> appears directly following <quote>microsoft</quote>
6926 in the page. This prevents links to microsoft.com from being trashed, while
6927 still replacing the word everywhere else.
6932 # Buzzword Bingo (example for extended regex syntax)
6934 s* industry[ -]leading \
6936 | customer[ -]focused \
6937 | market[ -]driven \
6938 | award[ -]winning # Comments are OK, too! \
6939 | high[ -]performance \
6940 | solutions[ -]based \
6944 *<font color="red"><b>BINGO!</b></font> \
6949 The <literal>x</literal> option in this job turns on extended syntax, and allows for
6950 e.g. the liberal use of (non-interpreted!) whitespace for nicer formatting.
6958 <!-- ~~~~~~~~ New section Header ~~~~~~~~~ -->
6960 <sect2 id="predefined-filters"><title>The Pre-defined Filters</title>
6964 Note each filter is also listed in the +filter action section above. Please
6965 keep these listings in sync.
6970 The distribution <filename>default.filter</filename> file contains a selection of
6971 pre-defined filters for your convenience:
6976 <term><emphasis>js-annoyances</emphasis></term>
6979 The purpose of this filter is to get rid of particularly annoying JavaScript abuse.
6984 replaces JavaScript references to the browser's referrer information
6985 with the string "Not Your Business!". This compliments the <literal><link
6986 linkend="hide-referrer">hide-referrer</link></literal> action on the content level.
6991 removes the bindings to the DOM's
6992 <ulink url="http://www.w3.org/TR/2000/REC-DOM-Level-2-Events-20001113/events.html#Events-eventgroupings-htmlevents">unload
6993 event</ulink> which we feel has no right to exist and is responsible for most <quote>exit consoles</quote>, i.e.
6994 nasty windows that pop up when you close another one.
6999 removes code that causes new windows to be opened with undesired properties, such as being
7000 full-screen, non-resizeable, without location, status or menu bar etc.
7006 Use with caution. This is an aggressive filter, and can break sites that
7007 rely heavily on JavaScript.
7013 <term><emphasis>js-events</emphasis></term>
7016 This is a very radical measure. It removes virtually all JavaScript event bindings, which
7017 means that scripts can not react to user actions such as mouse movements or clicks, window
7018 resizing etc, anymore. Use with caution!
7021 We <emphasis>strongly discourage</emphasis> using this filter as a default since it breaks
7022 many legitimate scripts. It is meant for use only on extra-nasty sites (should you really
7029 <term><emphasis>html-annoyances</emphasis></term>
7032 This filter will undo many common instances of HTML based abuse.
7035 The <literal>BLINK</literal> and <literal>MARQUEE</literal> tags
7036 are neutralized (yeah baby!), and browser windows will be created as
7037 resizeable (as of course they should be!), and will have location,
7038 scroll and menu bars -- even if specified otherwise.
7044 <term><emphasis>content-cookies</emphasis></term>
7047 Most cookies are set in the HTTP dialog, where they can be intercepted
7049 <literal><link linkend="crunch-incoming-cookies">crunch-incoming-cookies</link></literal>
7050 and <literal><link linkend="crunch-outgoing-cookies">crunch-outgoing-cookies</link></literal>
7051 actions. But web sites increasingly make use of HTML meta tags and JavaScript
7052 to sneak cookies to the browser on the content level.
7055 This filter disables most HTML and JavaScript code that reads or sets
7056 cookies. It cannot detect all clever uses of these types of code, so it
7057 should not be relied on as an absolute fix. Use it wherever you would also
7058 use the cookie crunch actions.
7064 <term><emphasis>refresh-tags</emphasis></term>
7067 Disable any refresh tags if the interval is greater than nine seconds (so
7068 that redirections done via refresh tags are not destroyed). This is useful
7069 for dial-on-demand setups, or for those who find this HTML feature
7076 <term><emphasis>unsolicited-popups</emphasis></term>
7079 This filter attempts to prevent only <quote>unsolicited</quote> pop-up
7080 windows from opening, yet still allow pop-up windows that the user
7081 has explicitly chosen to open. It was added in version 3.0.1,
7082 as an improvement over earlier such filters.
7085 Technical note: The filter works by redefining the window.open JavaScript
7086 function to a dummy function, <literal>PrivoxyWindowOpen()</literal>,
7087 during the loading and rendering phase of each HTML page access, and
7088 restoring the function afterward.
7091 This is recommended only for browsers that cannot perform this function
7092 reliably themselves. And be aware that some sites require such windows
7093 in order to function normally. Use with caution.
7099 <term><emphasis>all-popups</emphasis></term>
7102 Attempt to prevent <emphasis>all</emphasis> pop-up windows from opening.
7103 Note this should be used with even more discretion than the above, since
7104 it is more likely to break some sites that require pop-ups for normal
7105 usage. Use with caution.
7111 <term><emphasis>img-reorder</emphasis></term>
7114 This is a helper filter that has no value if used alone. It makes the
7115 <literal>banners-by-size</literal> and <literal>banners-by-link</literal>
7116 (see below) filters more effective and should be enabled together with them.
7122 <term><emphasis>banners-by-size</emphasis></term>
7125 This filter removes image tags purely based on what size they are. Fortunately
7126 for us, many ads and banner images tend to conform to certain standardized
7127 sizes, which makes this filter quite effective for ad stripping purposes.
7130 Occasionally this filter will cause false positives on images that are not ads,
7131 but just happen to be of one of the standard banner sizes.
7134 Recommended only for those who require extreme ad blocking. The default
7135 block rules should catch 95+% of all ads <emphasis>without</emphasis> this filter enabled.
7141 <term><emphasis>banners-by-link</emphasis></term>
7144 This is an experimental filter that attempts to kill any banners if
7145 their URLs seem to point to known or suspected click trackers. It is currently
7146 not of much value and is not recommended for use by default.
7152 <term><emphasis>webbugs</emphasis></term>
7155 Webbugs are small, invisible images (technically 1X1 GIF images), that
7156 are used to track users across websites, and collect information on them.
7157 As an HTML page is loaded by the browser, an embedded image tag causes the
7158 browser to contact a third-party site, disclosing the tracking information
7159 through the requested URL and/or cookies for that third-party domain, without
7160 the user ever becoming aware of the interaction with the third-party site.
7161 HTML-ized spam also uses a similar technique to verify email addresses.
7164 This filter removes the HTML code that loads such <quote>webbugs</quote>.
7170 <term><emphasis>tiny-textforms</emphasis></term>
7173 A rather special-purpose filter that can be used to enlarge textareas (those
7174 multi-line text boxes in web forms) and turn off hard word wrap in them.
7175 It was written for the sourceforge.net tracker system where such boxes are
7176 a nuisance, but it can be handy on other sites, too.
7179 It is not recommended to use this filter as a default.
7185 <term><emphasis>jumping-windows</emphasis></term>
7188 Many consider windows that move, or resize themselves to be abusive. This filter
7189 neutralizes the related JavaScript code. Note that some sites might not display
7190 or behave as intended when using this filter. Use with caution.
7196 <term><emphasis>frameset-borders</emphasis></term>
7199 Some web designers seem to assume that everyone in the world will view their
7200 web sites using the same browser brand and version, screen resolution etc,
7201 because only that assumption could explain why they'd use static frame sizes,
7202 yet prevent their frames from being resized by the user, should they be too
7203 small to show their whole content.
7206 This filter removes the related HTML code. It should only be applied to sites
7213 <term><emphasis>demoronizer</emphasis></term>
7216 Many Microsoft products that generate HTML use non-standard extensions (read:
7217 violations) of the ISO 8859-1 aka Latin-1 character set. This can cause those
7218 HTML documents to display with errors on standard-compliant platforms.
7221 This filter translates the MS-only characters into Latin-1 equivalents.
7222 It is not necessary when using MS products, and will cause corruption of
7223 all documents that use 8-bit character sets other than Latin-1. It's mostly
7224 worthwhile for Europeans on non-MS platforms, if weird garbage characters
7225 sometimes appear on some pages, or user agents that don't correct for this on
7228 My version of Mozilla (ancient) shows litte square boxes for quote
7229 characters, and apostrophes on moronized pages. So many pages have this, I
7230 can read them fine now. HB 08/27/06
7237 <term><emphasis>shockwave-flash</emphasis></term>
7240 A filter for shockwave haters. As the name suggests, this filter strips code
7241 out of web pages that is used to embed shockwave flash objects.
7249 <term><emphasis>quicktime-kioskmode</emphasis></term>
7252 Change HTML code that embeds Quicktime objects so that kioskmode, which
7253 prevents saving, is disabled.
7259 <term><emphasis>fun</emphasis></term>
7262 Text replacements for subversive browsing fun. Make fun of your favorite
7263 Monopolist or play buzzword bingo.
7269 <term><emphasis>crude-parental</emphasis></term>
7272 A demonstration-only filter that shows how <application>Privoxy</application>
7273 can be used to delete web content on a keyword basis.
7279 <term><emphasis>ie-exploits</emphasis></term>
7282 An experimental collection of text replacements to disable malicious HTML and JavaScript
7283 code that exploits known security holes in Internet Explorer.
7286 Presently, it only protects against Nimda and a cross-site scripting bug, and
7287 would need active maintenance to provide more substantial protection.
7293 <term><emphasis>site-specifics</emphasis></term>
7296 Some web sites have very specific problems, the cure for which doesn't apply
7297 anywhere else, or could even cause damage on other sites.
7300 This is a collection of such site-specific cures which should only be applied
7301 to the sites they were intended for, which is what the supplied
7302 <filename>default.action</filename> file does. Users shouldn't need to change
7303 anything regarding this filter.
7309 <term><emphasis>google</emphasis></term>
7312 A CSS based block for Google text ads. Also removes a width limitation
7313 and the toolbar advertisement.
7319 <term><emphasis>yahoo</emphasis></term>
7322 Another CSS based block, this time for Yahoo text ads. And removes
7323 a width limitation as well.
7329 <term><emphasis>msn</emphasis></term>
7332 Another CSS based block, this time for MSN text ads. And removes
7333 tracking URLs, as well as a width limitation.
7339 <term><emphasis>blogspot</emphasis></term>
7342 Cleans up some Blogspot blogs. Read the fine print before using this one!
7345 This filter also intentionally removes some navigation stuff and sets the
7346 page width to 100%. As a result, some rounded <quote>corners</quote> would
7347 appear to early or not at all and as fixing this would require a browser
7348 that understands background-size (CSS3), they are removed instead.
7354 <term><emphasis>xml-to-html</emphasis></term>
7357 Server-header filter to change the Content-Type from xml to html.
7363 <term><emphasis>html-to-xml</emphasis></term>
7366 Server-header filter to change the Content-Type from html to xml.
7372 <term><emphasis>no-ping</emphasis></term>
7375 Removes the non-standard <literal>ping</literal> attribute from
7376 anchor and area HTML tags.
7382 <term><emphasis>hide-tor-exit-notation</emphasis></term>
7385 Client-header filter to remove the <command>Tor</command> exit node notation
7386 found in Host and Referer headers.
7389 If &my-app; and <command>Tor</command> are chained and &my-app;
7390 is configured to use socks4a, one can use <quote>http://www.example.org.foobar.exit/</quote>
7391 to access the host <quote>www.example.org</quote> through the
7392 <command>Tor</command> exit node <quote>foobar</quote>.
7395 As the HTTP client isn't aware of this notation, it treats the
7396 whole string <quote>www.example.org.foobar.exit</quote> as host and uses it
7397 for the <quote>Host</quote> and <quote>Referer</quote> headers. From the
7398 server's point of view the resulting headers are invalid and can cause problems.
7401 An invalid <quote>Referer</quote> header can trigger <quote>hot-linking</quote>
7402 protections, an invalid <quote>Host</quote> header will make it impossible for
7403 the server to find the right vhost (several domains hosted on the same IP address).
7406 This client-header filter removes the <quote>foo.exit</quote> part in those headers
7407 to prevent the mentioned problems. Note that it only modifies
7408 the HTTP headers, it doesn't make it impossible for the server
7409 to detect your <command>Tor</command> exit node based on the IP address
7410 the request is coming from.
7417 <term><emphasis> </emphasis></term>
7430 <!-- ~~~~~~~~ New section Header ~~~~~~~~~ -->
7431 <sect2 id="external-filter-syntax"><title>External filter syntax</title>
7433 External filters are scripts or programs that can modify the content in
7434 case common <literal><link linkend="filter">filters</link></literal>
7435 aren't powerful enough.
7438 External filters can be written in any language the platform &my-app; runs
7442 They are controlled with the
7443 <literal><link linkend="external-filter">external-filter</link></literal> action
7444 and have to be defined in the <literal><link linkend="filterfile">filterfile</link></literal>
7448 The header looks like any other filter, but instead of pcrs jobs, external
7449 filters contain a single job which can be a program or a shell script (which
7450 may call other scripts or programs).
7453 External filters read the content from STDIN and write the rewritten
7454 content to STDOUT. The environment variables PRIVOXY_URL, PRIVOXY_PATH,
7455 PRIVOXY_HOST, PRIVOXY_ORIGIN can be used to get some details about the
7459 &my-app; will temporary store the content to filter in the
7460 <literal><link linkend="temporary-directory">temporary-directory</link></literal>.
7464 EXTERNAL-FILTER: cat Pointless example filter that doesn't actually modify the content
7467 # Incorrect reimplementation of the filter above in POSIX shell.
7469 # Note that it's a single job that spans multiple lines, the line
7470 # breaks are not passed to the shell, thus the semicolons are required.
7472 # If the script isn't trivial, it is recommended to put it into an external file.
7474 # In general, writing external filters entirely in POSIX shell is not
7475 # considered a good idea.
7476 EXTERNAL-FILTER: cat2 Pointless example filter that despite its name may actually modify the content
7482 EXTERNAL-FILTER: rotate-image Rotate an image by 180 degree. Test filter with limited value.
7483 /usr/local/bin/convert - -rotate 180 -
7485 EXTERNAL-FILTER: citation-needed Adds a "[citation needed]" tag to an image. The coordinates may need adjustment.
7486 /usr/local/bin/convert - -pointsize 16 -fill white -annotate +17+418 "[citation needed]" -
7492 Currently external filters are executed with &my-app;'s privileges!
7493 Only use external filters you understand and trust.
7497 External filters are experimental and the syntax may change in the future.
7503 <!-- ~ End section ~ -->
7507 <!-- ~~~~~ New section ~~~~~ -->
7509 <sect1 id="templates">
7510 <title>Privoxy's Template Files</title>
7512 All <application>Privoxy</application> built-in pages, i.e. error pages such as the
7513 <ulink url="http://show-the-404-error.page"><quote>404 - No Such Domain</quote>
7514 error page</ulink>, the <ulink
7515 url="http://ads.bannerserver.example.com/nasty-ads/sponsor.html"><quote>BLOCKED</quote>
7517 and all pages of its <ulink url="http://config.privoxy.org/">web-based
7518 user interface</ulink>, are generated from <emphasis>templates</emphasis>.
7519 (<application>Privoxy</application> must be running for the above links to work as
7524 These templates are stored in a subdirectory of the <link linkend="confdir">configuration
7525 directory</link> called <filename>templates</filename>. On Unixish platforms,
7527 <ulink url="file:///etc/privoxy/templates/"><filename>/etc/privoxy/templates/</filename></ulink>.
7531 The templates are basically normal HTML files, but with place-holders (called symbols
7532 or exports), which <application>Privoxy</application> fills at run time. It
7533 is possible to edit the templates with a normal text editor, should you want
7534 to customize them. (<emphasis>Not recommended for the casual
7535 user</emphasis>). Should you create your own custom templates, you should use
7536 the <filename>config</filename> setting <link linkend="templdir">templdir</link>
7537 to specify an alternate location, so your templates do not get overwritten
7541 Note that just like in configuration files, lines starting
7542 with <literal>#</literal> are ignored when the templates are filled in.
7546 The place-holders are of the form <literal>@name@</literal>, and you will
7547 find a list of available symbols, which vary from template to template,
7548 in the comments at the start of each file. Note that these comments are not
7549 always accurate, and that it's probably best to look at the existing HTML
7550 code to find out which symbols are supported and what they are filled in with.
7554 A special application of this substitution mechanism is to make whole
7555 blocks of HTML code disappear when a specific symbol is set. We use this
7556 for many purposes, one of them being to include the beta warning in all
7557 our user interface (CGI) pages when <application>Privoxy</application>
7558 is in an alpha or beta development stage:
7563 <!-- @if-unstable-start -->
7565 ... beta warning HTML code goes here ...
7567 <!-- if-unstable-end@ --></screen>
7571 If the "unstable" symbol is set, everything in between and including
7572 <literal>@if-unstable-start</literal> and <literal>if-unstable-end@</literal>
7573 will disappear, leaving nothing but an empty comment:
7577 <screen><!-- --></screen>
7581 There's also an if-then-else construct and an <literal>#include</literal>
7582 mechanism, but you'll sure find out if you are inclined to edit the
7587 All templates refer to a style located at
7588 <ulink url="http://config.privoxy.org/send-stylesheet"><literal>http://config.privoxy.org/send-stylesheet</literal></ulink>.
7589 This is, of course, locally served by <application>Privoxy</application>
7590 and the source for it can be found and edited in the
7591 <filename>cgi-style.css</filename> template.
7596 <!-- ~ End section ~ -->
7600 <!-- ~~~~~ New section ~~~~~ -->
7602 <sect1 id="contact"><title>Contacting the Developers, Bug Reporting and Feature
7605 <!-- Include contacting.sgml boilerplate: -->
7607 <!-- end boilerplate -->
7611 <!-- ~ End section ~ -->
7614 <!-- ~~~~~ New section ~~~~~ -->
7615 <sect1 id="copyright"><title>Privoxy Copyright, License and History</title>
7617 <!-- Include copyright.sgml: -->
7619 <!-- end copyright -->
7622 <application>Privoxy</application> is free software; you can
7623 redistribute it and/or modify it under the terms of the
7624 <citetitle>GNU General Public License</citetitle>, version 2,
7625 as published by the Free Software Foundation and included in
7629 <!-- ~~~~~ New section ~~~~~ -->
7630 <sect2 id="license"><title>License</title>
7632 <screen><![ RCDATA [ &GPLv2; ]]></screen>
7636 <!-- ~ End section ~ -->
7639 <!-- ~~~~~ New section ~~~~~ -->
7641 <sect2 id="history"><title>History</title>
7642 <!-- Include history.sgml: -->
7644 <!-- end history -->
7647 <sect2 id="authors"><title>Authors</title>
7648 <!-- Include p-authors.sgml: -->
7650 <!-- end authors -->
7655 <!-- ~ End section ~ -->
7658 <!-- ~~~~~ New section ~~~~~ -->
7659 <sect1 id="seealso"><title>See Also</title>
7660 <!-- Include seealso.sgml: -->
7662 <!-- end seealso -->
7667 <!-- ~~~~~ New section ~~~~~ -->
7668 <sect1 id="appendix"><title>Appendix</title>
7671 <!-- ~~~~~ New section ~~~~~ -->
7673 <title>Regular Expressions</title>
7675 <application>Privoxy</application> uses Perl-style <quote>regular
7676 expressions</quote> in its <link linkend="actions-file">actions
7677 files</link> and <link linkend="filter-file">filter file</link>,
7678 through the <ulink url="http://www.pcre.org/">PCRE</ulink> and
7681 <ulink url="http://www.oesterhelt.org/pcrs/">PCRS</ulink> libraries.
7683 <application>PCRS</application> libraries.
7687 If you are reading this, you probably don't understand what <quote>regular
7688 expressions</quote> are, or what they can do. So this will be a very brief
7689 introduction only. A full explanation would require a <ulink
7690 url="http://www.oreilly.com/catalog/regex/">book</ulink> ;-)
7694 Regular expressions provide a language to describe patterns that can be
7695 run against strings of characters (letter, numbers, etc), to see if they
7696 match the string or not. The patterns are themselves (sometimes complex)
7697 strings of literal characters, combined with wild-cards, and other special
7698 characters, called meta-characters. The <quote>meta-characters</quote> have
7699 special meanings and are used to build complex patterns to be matched against.
7700 Perl Compatible Regular Expressions are an especially convenient
7701 <quote>dialect</quote> of the regular expression language.
7705 To make a simple analogy, we do something similar when we use wild-card
7706 characters when listing files with the <command>dir</command> command in DOS.
7707 <literal>*.*</literal> matches all filenames. The <quote>special</quote>
7708 character here is the asterisk which matches any and all characters. We can be
7709 more specific and use <literal>?</literal> to match just individual
7710 characters. So <quote>dir file?.text</quote> would match
7711 <quote>file1.txt</quote>, <quote>file2.txt</quote>, etc. We are pattern
7712 matching, using a similar technique to <quote>regular expressions</quote>!
7716 Regular expressions do essentially the same thing, but are much, much more
7717 powerful. There are many more <quote>special characters</quote> and ways of
7718 building complex patterns however. Let's look at a few of the common ones,
7719 and then some examples:
7724 <emphasis>.</emphasis> - Matches any single character, e.g. <quote>a</quote>,
7725 <quote>A</quote>, <quote>4</quote>, <quote>:</quote>, or <quote>@</quote>.
7727 </simplelist></para>
7731 <emphasis>?</emphasis> - The preceding character or expression is matched ZERO or ONE
7734 </simplelist></para>
7738 <emphasis>+</emphasis> - The preceding character or expression is matched ONE or MORE
7741 </simplelist></para>
7745 <emphasis>*</emphasis> - The preceding character or expression is matched ZERO or MORE
7748 </simplelist></para>
7752 <emphasis>\</emphasis> - The <quote>escape</quote> character denotes that
7753 the following character should be taken literally. This is used where one of the
7754 special characters (e.g. <quote>.</quote>) needs to be taken literally and
7755 not as a special meta-character. Example: <quote>example\.com</quote>, makes
7756 sure the period is recognized only as a period (and not expanded to its
7757 meta-character meaning of any single character).
7759 </simplelist></para>
7763 <emphasis>[ ]</emphasis> - Characters enclosed in brackets will be matched if
7764 any of the enclosed characters are encountered. For instance, <quote>[0-9]</quote>
7765 matches any numeric digit (zero through nine). As an example, we can combine
7766 this with <quote>+</quote> to match any digit one of more times: <quote>[0-9]+</quote>.
7768 </simplelist></para>
7772 <emphasis>( )</emphasis> - parentheses are used to group a sub-expression,
7773 or multiple sub-expressions.
7775 </simplelist></para>
7779 <emphasis>|</emphasis> - The <quote>bar</quote> character works like an
7780 <quote>or</quote> conditional statement. A match is successful if the
7781 sub-expression on either side of <quote>|</quote> matches. As an example:
7782 <quote>/(this|that) example/</quote> uses grouping and the bar character
7783 and would match either <quote>this example</quote> or <quote>that
7784 example</quote>, and nothing else.
7786 </simplelist></para>
7789 These are just some of the ones you are likely to use when matching URLs with
7790 <application>Privoxy</application>, and is a long way from a definitive
7791 list. This is enough to get us started with a few simple examples which may
7792 be more illuminating:
7796 <emphasis><literal>/.*/banners/.*</literal></emphasis> - A simple example
7797 that uses the common combination of <quote>.</quote> and <quote>*</quote> to
7798 denote any character, zero or more times. In other words, any string at all.
7799 So we start with a literal forward slash, then our regular expression pattern
7800 (<quote>.*</quote>) another literal forward slash, the string
7801 <quote>banners</quote>, another forward slash, and lastly another
7802 <quote>.*</quote>. We are building
7803 a directory path here. This will match any file with the path that has a
7804 directory named <quote>banners</quote> in it. The <quote>.*</quote> matches
7805 any characters, and this could conceivably be more forward slashes, so it
7806 might expand into a much longer looking path. For example, this could match:
7807 <quote>/eye/hate/spammers/banners/annoy_me_please.gif</quote>, or just
7808 <quote>/banners/annoying.html</quote>, or almost an infinite number of other
7809 possible combinations, just so it has <quote>banners</quote> in the path
7814 And now something a little more complex:
7818 <emphasis><literal>/.*/adv((er)?ts?|ertis(ing|ements?))?/</literal></emphasis> -
7819 We have several literal forward slashes again (<quote>/</quote>), so we are
7820 building another expression that is a file path statement. We have another
7821 <quote>.*</quote>, so we are matching against any conceivable sub-path, just so
7822 it matches our expression. The only true literal that <emphasis>must
7823 match</emphasis> our pattern is <application>adv</application>, together with
7824 the forward slashes. What comes after the <quote>adv</quote> string is the
7829 Remember the <quote>?</quote> means the preceding expression (either a
7830 literal character or anything grouped with <quote>(...)</quote> in this case)
7831 can exist or not, since this means either zero or one match. So
7832 <quote>((er)?ts?|ertis(ing|ements?))</quote> is optional, as are the
7833 individual sub-expressions: <quote>(er)</quote>,
7834 <quote>(ing|ements?)</quote>, and the <quote>s</quote>. The <quote>|</quote>
7835 means <quote>or</quote>. We have two of those. For instance,
7836 <quote>(ing|ements?)</quote>, can expand to match either <quote>ing</quote>
7837 <emphasis>OR</emphasis> <quote>ements?</quote>. What is being done here, is an
7838 attempt at matching as many variations of <quote>advertisement</quote>, and
7839 similar, as possible. So this would expand to match just <quote>adv</quote>,
7840 or <quote>advert</quote>, or <quote>adverts</quote>, or
7841 <quote>advertising</quote>, or <quote>advertisement</quote>, or
7842 <quote>advertisements</quote>. You get the idea. But it would not match
7843 <quote>advertizements</quote> (with a <quote>z</quote>). We could fix that by
7844 changing our regular expression to:
7845 <quote>/.*/adv((er)?ts?|erti(s|z)(ing|ements?))?/</quote>, which would then match
7850 <emphasis><literal>/.*/advert[0-9]+\.(gif|jpe?g)</literal></emphasis> - Again
7851 another path statement with forward slashes. Anything in the square brackets
7852 <quote>[ ]</quote> can be matched. This is using <quote>0-9</quote> as a
7853 shorthand expression to mean any digit one through nine. It is the same as
7854 saying <quote>0123456789</quote>. So any digit matches. The <quote>+</quote>
7855 means one or more of the preceding expression must be included. The preceding
7856 expression here is what is in the square brackets -- in this case, any digit
7857 one through nine. Then, at the end, we have a grouping: <quote>(gif|jpe?g)</quote>.
7858 This includes a <quote>|</quote>, so this needs to match the expression on
7859 either side of that bar character also. A simple <quote>gif</quote> on one side, and the other
7860 side will in turn match either <quote>jpeg</quote> or <quote>jpg</quote>,
7861 since the <quote>?</quote> means the letter <quote>e</quote> is optional and
7862 can be matched once or not at all. So we are building an expression here to
7863 match image GIF or JPEG type image file. It must include the literal
7864 string <quote>advert</quote>, then one or more digits, and a <quote>.</quote>
7865 (which is now a literal, and not a special character, since it is escaped
7866 with <quote>\</quote>), and lastly either <quote>gif</quote>, or
7867 <quote>jpeg</quote>, or <quote>jpg</quote>. Some possible matches would
7868 include: <quote>//advert1.jpg</quote>,
7869 <quote>/nasty/ads/advert1234.gif</quote>,
7870 <quote>/banners/from/hell/advert99.jpg</quote>. It would not match
7871 <quote>advert1.gif</quote> (no leading slash), or
7872 <quote>/adverts232.jpg</quote> (the expression does not include an
7873 <quote>s</quote>), or <quote>/advert1.jsp</quote> (<quote>jsp</quote> is not
7874 in the expression anywhere).
7878 We are barely scratching the surface of regular expressions here so that you
7879 can understand the default <application>Privoxy</application>
7880 configuration files, and maybe use this knowledge to customize your own
7881 installation. There is much, much more that can be done with regular
7882 expressions. Now that you know enough to get started, you can learn more on
7887 More reading on Perl Compatible Regular expressions:
7888 <ulink url="http://perldoc.perl.org/perlre.html">http://perldoc.perl.org/perlre.html</ulink>
7892 For information on regular expression based substitutions and their applications
7893 in filters, please see the <link linkend="filter-file">filter file tutorial</link>
7898 <!-- ~ End section ~ -->
7901 <!-- ~~~~~ New section ~~~~~ -->
7903 <title>Privoxy's Internal Pages</title>
7906 Since <application>Privoxy</application> proxies each requested
7907 web page, it is easy for <application>Privoxy</application> to
7908 trap certain special URLs. In this way, we can talk directly to
7909 <application>Privoxy</application>, and see how it is
7910 configured, see how our rules are being applied, change these
7911 rules and other configuration options, and even turn
7912 <application>Privoxy's</application> filtering off, all with
7918 The URLs listed below are the special ones that allow direct access
7919 to <application>Privoxy</application>. Of course,
7920 <application>Privoxy</application> must be running to access these. If
7921 not, you will get a friendly error message. Internet access is not
7934 <ulink url="http://config.privoxy.org/">http://config.privoxy.org/</ulink>
7938 There is a shortcut: <ulink url="http://p.p/">http://p.p/</ulink> (But it
7939 doesn't provide a fall-back to a real page, in case the request is not
7940 sent through <application>Privoxy</application>)
7946 Show information about the current configuration, including viewing and
7947 editing of actions files:
7951 <ulink url="http://config.privoxy.org/show-status">http://config.privoxy.org/show-status</ulink>
7958 Show the source code version numbers:
7962 <ulink url="http://config.privoxy.org/show-version">http://config.privoxy.org/show-version</ulink>
7969 Show the browser's request headers:
7973 <ulink url="http://config.privoxy.org/show-request">http://config.privoxy.org/show-request</ulink>
7980 Show which actions apply to a URL and why:
7984 <ulink url="http://config.privoxy.org/show-url-info">http://config.privoxy.org/show-url-info</ulink>
7991 Toggle Privoxy on or off. This feature can be turned off/on in the main
7992 <filename>config</filename> file. When toggled <quote>off</quote>, <quote>Privoxy</quote>
7993 continues to run, but only as a pass-through proxy, with no actions taking
7998 <ulink url="http://config.privoxy.org/toggle">http://config.privoxy.org/toggle</ulink>
8002 Short cuts. Turn off, then on:
8006 <ulink url="http://config.privoxy.org/toggle?set=disable">http://config.privoxy.org/toggle?set=disable</ulink>
8011 <ulink url="http://config.privoxy.org/toggle?set=enable">http://config.privoxy.org/toggle?set=enable</ulink>
8022 <!-- ~~~~~ New section ~~~~~ -->
8024 <title>Chain of Events</title>
8026 Let's take a quick look at how some of <application>Privoxy's</application>
8027 core features are triggered, and the ensuing sequence of events when a web
8028 page is requested by your browser:
8035 First, your web browser requests a web page. The browser knows to send
8036 the request to <application>Privoxy</application>, which will in turn,
8037 relay the request to the remote web server after passing the following
8043 <application>Privoxy</application> traps any request for its own internal CGI
8044 pages (e.g <ulink url="http://p.p/">http://p.p/</ulink>) and sends the CGI page back to the browser.
8049 Next, <application>Privoxy</application> checks to see if the URL
8051 linkend="BLOCK"><quote>+block</quote></link> patterns. If
8052 so, the URL is then blocked, and the remote web server will not be contacted.
8053 <link linkend="HANDLE-AS-IMAGE"><quote>+handle-as-image</quote></link>
8055 <link linkend="HANDLE-AS-EMPTY-DOCUMENT"><quote>+handle-as-empty-document</quote></link>
8056 are then checked, and if there is no match, an
8057 HTML <quote>BLOCKED</quote> page is sent back to the browser. Otherwise, if
8058 it does match, an image is returned for the former, and an empty text
8059 document for the latter. The type of image would depend on the setting of
8060 <link linkend="SET-IMAGE-BLOCKER"><quote>+set-image-blocker</quote></link>
8061 (blank, checkerboard pattern, or an HTTP redirect to an image elsewhere).
8066 Untrusted URLs are blocked. If URLs are being added to the
8067 <filename>trust</filename> file, then that is done.
8072 If the URL pattern matches the <link
8073 linkend="FAST-REDIRECTS"><quote>+fast-redirects</quote></link> action,
8074 it is then processed. Unwanted parts of the requested URL are stripped.
8079 Now the rest of the client browser's request headers are processed. If any
8080 of these match any of the relevant actions (e.g. <link
8081 linkend="HIDE-USER-AGENT"><quote>+hide-user-agent</quote></link>,
8082 etc.), headers are suppressed or forged as determined by these actions and
8088 Now the web server starts sending its response back (i.e. typically a web
8094 First, the server headers are read and processed to determine, among other
8095 things, the MIME type (document type) and encoding. The headers are then
8096 filtered as determined by the
8097 <link linkend="CRUNCH-INCOMING-COOKIES"><quote>+crunch-incoming-cookies</quote></link>,
8098 <link linkend="SESSION-COOKIES-ONLY"><quote>+session-cookies-only</quote></link>,
8099 and <link linkend="DOWNGRADE-HTTP-VERSION"><quote>+downgrade-http-version</quote></link>
8105 If any <link linkend="FILTER"><quote>+filter</quote></link> action
8107 linkend="DEANIMATE-GIFS"><quote>+deanimate-gifs</quote></link>
8108 action applies (and the document type fits the action), the rest of the page is
8109 read into memory (up to a configurable limit). Then the filter rules (from
8110 <filename>default.filter</filename> and any other filter files) are
8111 processed against the buffered content. Filters are applied in the order
8112 they are specified in one of the filter files. Animated GIFs, if present,
8113 are reduced to either the first or last frame, depending on the action
8114 setting.The entire page, which is now filtered, is then sent by
8115 <application>Privoxy</application> back to your browser.
8118 If neither a <link linkend="FILTER"><quote>+filter</quote></link> action
8120 linkend="DEANIMATE-GIFS"><quote>+deanimate-gifs</quote></link>
8121 matches, then <application>Privoxy</application> passes the raw data through
8122 to the client browser as it becomes available.
8127 As the browser receives the now (possibly filtered) page content, it
8128 reads and then requests any URLs that may be embedded within the page
8129 source, e.g. ad images, stylesheets, JavaScript, other HTML documents (e.g.
8130 frames), sounds, etc. For each of these objects, the browser issues a
8131 separate request (this is easily viewable in <application>Privoxy's</application>
8132 logs). And each such request is in turn processed just as above. Note that a
8133 complex web page will have many, many such embedded URLs. If these
8134 secondary requests are to a different server, then quite possibly a very
8135 differing set of actions is triggered.
8142 NOTE: This is somewhat of a simplistic overview of what happens with each URL
8143 request. For the sake of brevity and simplicity, we have focused on
8144 <application>Privoxy's</application> core features only.
8150 <!-- ~~~~~ New section ~~~~~ -->
8151 <sect2 id="actionsanat">
8152 <title>Troubleshooting: Anatomy of an Action</title>
8155 The way <application>Privoxy</application> applies
8156 <link linkend="ACTIONS">actions</link> and <link linkend="FILTER">filters</link>
8157 to any given URL can be complex, and not always so
8158 easy to understand what is happening. And sometimes we need to be able to
8159 <emphasis>see</emphasis> just what <application>Privoxy</application> is
8160 doing. Especially, if something <application>Privoxy</application> is doing
8161 is causing us a problem inadvertently. It can be a little daunting to look at
8162 the actions and filters files themselves, since they tend to be filled with
8163 <link linkend="regex">regular expressions</link> whose consequences are not
8168 One quick test to see if <application>Privoxy</application> is causing a problem
8169 or not, is to disable it temporarily. This should be the first troubleshooting
8170 step (be sure to flush caches afterward!). Looking at the
8171 logs is a good idea too. (Note that both the toggle feature and logging are
8172 enabled via <filename>config</filename> file settings, and may need to be
8173 turned <quote>on</quote>.)
8176 Another easy troubleshooting step to try is if you have done any
8177 customization of your installation, revert back to the installed
8178 defaults and see if that helps. There are times the developers get complaints
8179 about one thing or another, and the problem is more related to a customized
8180 configuration issue.
8184 <application>Privoxy</application> also provides the
8185 <ulink url="http://config.privoxy.org/show-url-info">http://config.privoxy.org/show-url-info</ulink>
8186 page that can show us very specifically how <application>actions</application>
8187 are being applied to any given URL. This is a big help for troubleshooting.
8191 First, enter one URL (or partial URL) at the prompt, and then
8192 <application>Privoxy</application> will tell us
8193 how the current configuration will handle it. This will not
8194 help with filtering effects (i.e. the <link
8195 linkend="FILTER"><quote>+filter</quote></link> action) from
8196 one of the filter files since this is handled very
8197 differently and not so easy to trap! It also will not tell you about any other
8198 URLs that may be embedded within the URL you are testing. For instance, images
8199 such as ads are expressed as URLs within the raw page source of HTML pages. So
8200 you will only get info for the actual URL that is pasted into the prompt area
8201 -- not any sub-URLs. If you want to know about embedded URLs like ads, you
8202 will have to dig those out of the HTML source. Use your browser's <quote>View
8203 Page Source</quote> option for this. Or right click on the ad, and grab the
8208 Let's try an example, <ulink url="http://google.com">google.com</ulink>,
8209 and look at it one section at a time in a sample configuration (your real
8210 configuration may vary):
8215 Matches for http://www.google.com:
8217 In file: default.action <guibutton>[ View ]</guibutton> <guibutton>[ Edit ]</guibutton>
8219 {+change-x-forwarded-for{block}
8220 +deanimate-gifs {last}
8221 +fast-redirects {check-decoded-url}
8222 +filter {refresh-tags}
8223 +filter {img-reorder}
8224 +filter {banners-by-size}
8226 +filter {jumping-windows}
8227 +filter {ie-exploits}
8228 +hide-from-header {block}
8229 +hide-referrer {forge}
8230 +session-cookies-only
8231 +set-image-blocker {pattern}
8234 { -session-cookies-only }
8240 In file: user.action <guibutton>[ View ]</guibutton> <guibutton>[ Edit ]</guibutton>
8241 (no matches in this file)
8246 This is telling us how we have defined our
8247 <link linkend="ACTIONS"><quote>actions</quote></link>, and
8248 which ones match for our test case, <quote>google.com</quote>.
8249 Displayed is all the actions that are available to us. Remember,
8250 the <literal>+</literal> sign denotes <quote>on</quote>. <literal>-</literal>
8251 denotes <quote>off</quote>. So some are <quote>on</quote> here, but many
8252 are <quote>off</quote>. Each example we try may provide a slightly different
8253 end result, depending on our configuration directives.
8257 is for our <filename>default.action</filename> file. The large, multi-line
8258 listing, is how the actions are set to match for all URLs, i.e. our default
8259 settings. If you look at your <quote>actions</quote> file, this would be the
8260 section just below the <quote>aliases</quote> section near the top. This
8261 will apply to all URLs as signified by the single forward slash at the end
8262 of the listing -- <quote> / </quote>.
8266 But we have defined additional actions that would be exceptions to these general
8267 rules, and then we list specific URLs (or patterns) that these exceptions
8268 would apply to. Last match wins. Just below this then are two explicit
8269 matches for <quote>.google.com</quote>. The first is negating our previous
8270 cookie setting, which was for <link
8271 linkend="SESSION-COOKIES-ONLY"><quote>+session-cookies-only</quote></link>
8272 (i.e. not persistent). So we will allow persistent cookies for google, at
8273 least that is how it is in this example. The second turns
8274 <emphasis>off</emphasis> any <link
8275 linkend="FAST-REDIRECTS"><quote>+fast-redirects</quote></link>
8276 action, allowing this to take place unmolested. Note that there is a leading
8277 dot here -- <quote>.google.com</quote>. This will match any hosts and
8278 sub-domains, in the google.com domain also, such as
8279 <quote>www.google.com</quote> or <quote>mail.google.com</quote>. But it would not
8280 match <quote>www.google.de</quote>! So, apparently, we have these two actions
8281 defined as exceptions to the general rules at the top somewhere in the lower
8282 part of our <filename>default.action</filename> file, and
8283 <quote>google.com</quote> is referenced somewhere in these latter sections.
8287 Then, for our <filename>user.action</filename> file, we again have no hits.
8288 So there is nothing google-specific that we might have added to our own, local
8289 configuration. If there was, those actions would over-rule any actions from
8290 previously processed files, such as <filename>default.action</filename>.
8291 <filename>user.action</filename> typically has the last word. This is the
8292 best place to put hard and fast exceptions,
8296 And finally we pull it all together in the bottom section and summarize how
8297 <application>Privoxy</application> is applying all its <quote>actions</quote>
8298 to <quote>google.com</quote>:
8309 +change-x-forwarded-for{block}
8310 -client-header-filter{hide-tor-exit-notation}
8311 -content-type-overwrite
8312 -crunch-client-header
8313 -crunch-if-none-match
8314 -crunch-incoming-cookies
8315 -crunch-outgoing-cookies
8316 -crunch-server-header
8317 +deanimate-gifs {last}
8318 -downgrade-http-version
8321 -filter {content-cookies}
8322 -filter {all-popups}
8323 -filter {banners-by-link}
8324 -filter {tiny-textforms}
8325 -filter {frameset-borders}
8326 -filter {demoronizer}
8327 -filter {shockwave-flash}
8328 -filter {quicktime-kioskmode}
8330 -filter {crude-parental}
8331 -filter {site-specifics}
8332 -filter {js-annoyances}
8333 -filter {html-annoyances}
8334 +filter {refresh-tags}
8335 -filter {unsolicited-popups}
8336 +filter {img-reorder}
8337 +filter {banners-by-size}
8339 +filter {jumping-windows}
8340 +filter {ie-exploits}
8347 -handle-as-empty-document
8349 -hide-accept-language
8350 -hide-content-disposition
8351 +hide-from-header {block}
8352 -hide-if-modified-since
8353 +hide-referrer {forge}
8356 -overwrite-last-modified
8357 -prevent-compression
8359 -server-header-filter{xml-to-html}
8360 -server-header-filter{html-to-xml}
8361 -session-cookies-only
8362 +set-image-blocker {pattern} </screen>
8366 Notice the only difference here to the previous listing, is to
8367 <quote>fast-redirects</quote> and <quote>session-cookies-only</quote>,
8368 which are activated specifically for this site in our configuration,
8369 and thus show in the <quote>Final Results</quote>.
8373 Now another example, <quote>ad.doubleclick.net</quote>:
8379 { +block{Domains starts with "ad"} }
8382 { +block{Domain contains "ad"} }
8385 { +block{Doubleclick banner server} +handle-as-image }
8386 .[a-vx-z]*.doubleclick.net
8391 We'll just show the interesting part here - the explicit matches. It is
8392 matched three different times. Two <quote>+block{}</quote> sections,
8393 and a <quote>+block{} +handle-as-image</quote>,
8394 which is the expanded form of one of our aliases that had been defined as:
8395 <quote>+block-as-image</quote>. (<link
8396 linkend="ALIASES"><quote>Aliases</quote></link> are defined in
8397 the first section of the actions file and typically used to combine more
8402 Any one of these would have done the trick and blocked this as an unwanted
8403 image. This is unnecessarily redundant since the last case effectively
8404 would also cover the first. No point in taking chances with these guys
8405 though ;-) Note that if you want an ad or obnoxious
8406 URL to be invisible, it should be defined as <quote>ad.doubleclick.net</quote>
8407 is done here -- as both a <link
8408 linkend="BLOCK"><quote>+block{}</quote></link>
8409 <emphasis>and</emphasis> an
8410 <link linkend="HANDLE-AS-IMAGE"><quote>+handle-as-image</quote></link>.
8411 The custom alias <quote><literal>+block-as-image</literal></quote> just
8412 simplifies the process and make it more readable.
8416 One last example. Let's try <quote>http://www.example.net/adsl/HOWTO/</quote>.
8417 This one is giving us problems. We are getting a blank page. Hmmm ...
8423 Matches for http://www.example.net/adsl/HOWTO/:
8425 In file: default.action <guibutton>[ View ]</guibutton> <guibutton>[ Edit ]</guibutton>
8429 +change-x-forwarded-for{block}
8430 -client-header-filter{hide-tor-exit-notation}
8431 -content-type-overwrite
8432 -crunch-client-header
8433 -crunch-if-none-match
8434 -crunch-incoming-cookies
8435 -crunch-outgoing-cookies
8436 -crunch-server-header
8438 -downgrade-http-version
8439 +fast-redirects {check-decoded-url}
8441 -filter {content-cookies}
8442 -filter {all-popups}
8443 -filter {banners-by-link}
8444 -filter {tiny-textforms}
8445 -filter {frameset-borders}
8446 -filter {demoronizer}
8447 -filter {shockwave-flash}
8448 -filter {quicktime-kioskmode}
8450 -filter {crude-parental}
8451 -filter {site-specifics}
8452 -filter {js-annoyances}
8453 -filter {html-annoyances}
8454 +filter {refresh-tags}
8455 -filter {unsolicited-popups}
8456 +filter {img-reorder}
8457 +filter {banners-by-size}
8459 +filter {jumping-windows}
8460 +filter {ie-exploits}
8467 -handle-as-empty-document
8469 -hide-accept-language
8470 -hide-content-disposition
8471 +hide-from-header{block}
8472 +hide-referer{forge}
8474 -overwrite-last-modified
8475 +prevent-compression
8477 -server-header-filter{xml-to-html}
8478 -server-header-filter{html-to-xml}
8479 +session-cookies-only
8480 +set-image-blocker{blank} }
8483 { +block{Path contains "ads".} +handle-as-image }
8489 Ooops, the <quote>/adsl/</quote> is matching <quote>/ads</quote> in our
8490 configuration! But we did not want this at all! Now we see why we get the
8491 blank page. It is actually triggering two different actions here, and
8492 the effects are aggregated so that the URL is blocked, and &my-app; is told
8493 to treat the block as if it were an image. But this is, of course, all wrong.
8494 We could now add a new action below this (or better in our own
8495 <filename>user.action</filename> file) that explicitly
8496 <emphasis>un</emphasis> blocks (
8497 <link linkend="BLOCK"><quote>{-block}</quote></link>) paths with
8498 <quote>adsl</quote> in them (remember, last match in the configuration
8499 wins). There are various ways to handle such exceptions. Example:
8511 Now the page displays ;-)
8512 Remember to flush your browser's caches when making these kinds of changes to
8513 your configuration to insure that you get a freshly delivered page! Or, try
8514 using <literal>Shift+Reload</literal>.
8518 But now what about a situation where we get no explicit matches like
8525 { +block{Path starts with "ads".} +handle-as-image }
8531 That actually was very helpful and pointed us quickly to where the problem
8532 was. If you don't get this kind of match, then it means one of the default
8533 rules in the first section of <filename>default.action</filename> is causing
8534 the problem. This would require some guesswork, and maybe a little trial and
8535 error to isolate the offending rule. One likely cause would be one of the
8536 <link linkend="FILTER"><quote>+filter</quote></link> actions.
8537 These tend to be harder to troubleshoot.
8538 Try adding the URL for the site to one of aliases that turn off
8539 <link linkend="FILTER"><quote>+filter</quote></link>:
8547 .worldpay.com # for quietpc.com
8555 <quote><literal>{ shop }</literal></quote> is an <quote>alias</quote> that expands to
8556 <quote><literal>{ -filter -session-cookies-only }</literal></quote>.
8557 Or you could do your own exception to negate filtering:
8565 # Disable ALL filter actions for sites in this section
8573 This would turn off all filtering for these sites. This is best
8574 put in <filename>user.action</filename>, for local site
8575 exceptions. Note that when a simple domain pattern is used by itself (without
8576 the subsequent path portion), all sub-pages within that domain are included
8577 automatically in the scope of the action.
8581 Images that are inexplicably being blocked, may well be hitting the
8582 <link linkend="FILTER-BANNERS-BY-SIZE"><quote>+filter{banners-by-size}</quote></link>
8584 that images of certain sizes are ad banners (works well
8585 <emphasis>most of the time</emphasis> since these tend to be standardized).
8589 <quote><literal>{ fragile }</literal></quote> is an alias that disables most
8590 actions that are the most likely to cause trouble. This can be used as a
8591 last resort for problem sites.
8597 # Handle with care: easy to break
8599 mybank.example.com</screen>
8604 <emphasis>Remember to flush caches!</emphasis> Note that the
8605 <literal>mail.google</literal> reference lacks the TLD portion (e.g.
8606 <quote>.com</quote>). This will effectively match any TLD with
8607 <literal>google</literal> in it, such as <literal>mail.google.de.</literal>,
8611 If this still does not work, you will have to go through the remaining
8612 actions one by one to find which one(s) is causing the problem.
8621 This program is free software; you can redistribute it
8622 and/or modify it under the terms of the GNU General
8623 Public License as published by the Free Software
8624 Foundation; either version 2 of the License, or (at
8625 your option) any later version.
8627 This program is distributed in the hope that it will
8628 be useful, but WITHOUT ANY WARRANTY; without even the
8629 implied warranty of MERCHANTABILITY or FITNESS FOR A
8630 PARTICULAR PURPOSE. See the GNU General Public
8631 License for more details.
8633 The GNU General Public License should be included with
8634 this file. If not, you can view it at
8635 http://www.gnu.org/copyleft/gpl.html
8636 or write to the Free Software Foundation, Inc.,
8637 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,