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 "3.0.24">
17 <!entity p-status "stable">
18 <!entity % p-authors-formal "INCLUDE"> <!-- include additional text, etc -->
19 <!entity % p-not-stable "IGNORE">
20 <!entity % p-stable "INCLUDE">
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 2.199 2016/01/21 15:55:49 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 2.199 2016/01/21 15:55:49 fabiankeil Exp $</pubdate>
69 Note: the following should generate a separate page, and a live link to it,
70 all nicely done. But it doesn't for some mysterious reason. Please leave
71 commented unless it can be fixed proper. For the time being, the
72 copyright/license declarations will be in their own sgml.
85 This is here to keep vim syntax file from breaking :/
86 If I knew enough to fix it, I would.
87 PLEASE DO NOT REMOVE! HB: hal@foobox.net
93 The <citetitle>Privoxy User Manual</citetitle> gives users information on how to
94 install, configure and use <ulink
95 url="http://www.privoxy.org/">Privoxy</ulink>.
98 <!-- Include privoxy.sgml boilerplate: -->
100 <!-- end privoxy.sgml -->
103 You can find the latest version of the <citetitle>Privoxy User Manual</citetitle> at <ulink
104 url="http://www.privoxy.org/user-manual/">http://www.privoxy.org/user-manual/</ulink>.
105 Please see the <link linkend="contact">Contact section</link> on how to
106 contact the developers.
110 <!-- Feel free to send a note to the developers at <email>ijbswa-developers@lists.sourceforge.net</email>. -->
116 <!-- ~~~~~ New section ~~~~~ -->
117 <sect1 label="1" id="introduction"><title>Introduction</title>
119 This documentation is included with the current &p-status; version of
120 <application>Privoxy</application>, &p-version;<![%p-not-stable;[,
121 and is mostly complete at this point. The most up to date reference for the
122 time being is still the comments in the source files and in the individual
123 configuration files. Development of a new version is currently nearing
124 completion, and includes significant changes and enhancements over
128 <!-- include only in non-stable versions -->
131 Since this is a &p-status; version, not all new features are well tested. This
132 documentation may be slightly out of sync as a result (especially with
133 CVS sources). And there <emphasis>may be</emphasis> bugs, though hopefully
138 <!-- ~~~~~ New section ~~~~~ -->
139 <sect2 id="features"><title>Features</title>
141 In addition to the core
142 features of ad blocking and
143 <ulink url="http://en.wikipedia.org/wiki/Browser_cookie">cookie</ulink> management,
144 <application>Privoxy</application> provides many supplemental
145 features<![%p-not-stable;[, some of them currently under development]]>,
146 that give the end-user more control, more privacy and more freedom:
148 <!-- Include newfeatures.sgml boilerplate here: -->
150 <!-- end boilerplate -->
155 <!-- ~ End section ~ -->
158 <!-- ~~~~~ New section ~~~~~ -->
159 <sect1 id="installation"><title>Installation</title>
162 <application>Privoxy</application> is available both in convenient pre-compiled
163 packages for a wide range of operating systems, and as raw source code.
164 For most users, we recommend using the packages, which can be downloaded from our
165 <ulink url="http://sourceforge.net/projects/ijbswa/">Privoxy Project
171 On some platforms, the installer may remove previously installed versions, if
172 found. (See below for your platform). In any case <emphasis>be sure to backup
173 your old configuration if it is valuable to you.</emphasis> See the <link
174 linkend="upgradersnote">note to upgraders</link> section below.
177 <!-- ~~~~~ New section ~~~~~ -->
178 <sect2 id="installation-packages"><title>Binary Packages</title>
180 How to install the binary packages depends on your operating system:
183 <!-- XXX: The installation sections should be sorted -->
185 <!-- ~~~~~ New section ~~~~~ -->
186 <sect3 id="installation-deb"><title>Debian and Ubuntu</title>
188 DEBs can be installed with <literal>apt-get install privoxy</literal>,
189 and will use <filename>/etc/privoxy</filename> for the location of
194 <!-- ~~~~~ New section ~~~~~ -->
195 <sect3 id="installation-pack-win"><title>Windows</title>
198 Just double-click the installer, which will guide you through
199 the installation process. You will find the configuration files
200 in the same directory as you installed <application>Privoxy</application> in.
203 Version 3.0.5 beta introduced full <application>Windows</application> service
204 functionality. On Windows only, the <application>Privoxy</application>
205 program has two new command line arguments to install and uninstall
206 <application>Privoxy</application> as a <emphasis>service</emphasis>.
210 <term>Arguments:</term>
213 <replaceable class="parameter">--install</replaceable>[:<replaceable class="parameter">service_name</replaceable>]
216 <replaceable class="parameter">--uninstall</replaceable>[:<replaceable class="parameter">service_name</replaceable>]
222 After invoking <application>Privoxy</application> with
223 <command>--install</command>, you will need to bring up the
224 <application>Windows</application> service console to assign the user you
225 want <application>Privoxy</application> to run under, and whether or not you
226 want it to run whenever the system starts. You can start the
227 <application>Windows</application> services console with the following
228 command: <command>services.msc</command>. If you do not take the manual step
229 of modifying <application>Privoxy's</application> service settings, it will
230 not start. Note too that you will need to give Privoxy a user account that
231 actually exists, or it will not be permitted to
232 write to its log and configuration files.
237 <!-- ~~~~~ New section ~~~~~ -->
238 <sect3 id="installation-os2"><title>OS/2</title>
241 First, make sure that no previous installations of
242 <application>Junkbuster</application> and / or
243 <application>Privoxy</application> are left on your
244 system. Check that no <application>Junkbuster</application>
245 or <application>Privoxy</application> objects are in
251 Then, just double-click the WarpIN self-installing archive, which will
252 guide you through the installation process. A shadow of the
253 <application>Privoxy</application> executable will be placed in your
254 startup folder so it will start automatically whenever OS/2 starts.
258 The directory you choose to install <application>Privoxy</application>
259 into will contain all of the configuration files.
263 <!-- ~~~~~ New section ~~~~~ -->
264 <sect3 id="installation-mac"><title>Mac OS X</title>
266 Installation instructions for the OS X platform depend upon whether
267 you downloaded a ready-built installation package (.pkg or .mpkg) or have
268 downloaded the source code.
271 <sect3 renderas="sect4" id="OS-X-install-from-package">
272 <title>Installation from ready-built package</title>
274 The downloaded file will either be a .pkg (for OS X 10.5 upwards) or a bzipped
275 .mpkg file (for OS X 10.4). The former can be double-clicked as is and the
276 installation will start; double-clicking the latter will unzip the .mpkg file
277 which can then be double-clicked to commence the installation.
280 The privoxy service will automatically start after a successful installation
281 (and thereafter every time your computer starts up) however you will need to
282 configure your web browser(s) to use it. To do so, configure them to use a
283 proxy for HTTP and HTTPS at the address 127.0.0.1:8118.
286 To prevent the privoxy service from automatically starting when your computer
287 starts up, remove or rename the file <literal>/Library/LaunchDaemons/org.ijbswa.privoxy.plist</literal>
288 (on OS X 10.5 and higher) or the folder named
289 <literal>/Library/StartupItems/Privoxy</literal> (on OS X 10.4 'Tiger').
292 To manually start or stop the privoxy service, use the scripts startPrivoxy.sh
293 and stopPrivoxy.sh supplied in /Applications/Privoxy. They must be run from an
294 administrator account, using sudo.
297 To uninstall, run /Applications/Privoxy/uninstall.command as sudo from an
298 administrator account.
301 <sect3 renderas="sect4" id="OS-X-install-from-source">
302 <title>Installation from source</title>
304 To build and install the Privoxy source code on OS X you will need to obtain
305 the macsetup module from the Privoxy Sourceforge CVS repository (refer to
306 Sourceforge help for details of how to set up a CVS client to have read-only
307 access to the repository). This module contains scripts that leverage the usual
308 open-source tools (available as part of Apple's free of charge Xcode
309 distribution or via the usual open-source software package managers for OS X
310 (MacPorts, Homebrew, Fink etc.) to build and then install the privoxy binary
311 and associated files. The macsetup module's README file contains complete
312 instructions for its use.
315 The privoxy service will automatically start after a successful installation
316 (and thereafter every time your computer starts up) however you will need to
317 configure your web browser(s) to use it. To do so, configure them to use a
318 proxy for HTTP and HTTPS at the address 127.0.0.1:8118.
321 To prevent the privoxy service from automatically starting when your computer
322 starts up, remove or rename the file <literal>/Library/LaunchDaemons/org.ijbswa.privoxy.plist</literal>
323 (on OS X 10.5 and higher) or the folder named
324 <literal>/Library/StartupItems/Privoxy</literal> (on OS X 10.4 'Tiger').
327 To manually start or stop the privoxy service, use the Privoxy Utility
328 for Mac OS X (also part of the macsetup module). This application can start
329 and stop the privoxy service and display its log and configuration files.
332 To uninstall, run the macsetup module's uninstall.sh as sudo from an
333 administrator account.
337 <!-- ~~~~~ New section ~~~~~ -->
338 <sect3 id="installation-freebsd"><title>FreeBSD</title>
341 Privoxy is part of FreeBSD's Ports Collection, you can build and install
342 it with <literal>cd /usr/ports/www/privoxy; make install clean</literal>.
348 <!-- ~~~~~ New section ~~~~~ -->
349 <sect2 id="installation-source"><title>Building from Source</title>
352 The most convenient way to obtain the <application>Privoxy</application> sources
353 is to download the source tarball from our
354 <ulink url="http://sourceforge.net/project/showfiles.php?group_id=11118&package_id=10571">project download
359 If you like to live on the bleeding edge and are not afraid of using
360 possibly unstable development versions, you can check out the up-to-the-minute
361 version directly from <ulink url="http://sourceforge.net/cvs/?group_id=11118">the
362 CVS repository</ulink>.
364 deprecated...out of business.
365 or simply download <ulink
366 url="http://cvs.sourceforge.net/cvstarballs/ijbswa-cvsroot.tar.bz2">the nightly CVS
371 <!-- include buildsource.sgml boilerplate: -->
373 <!-- end boilerplate -->
376 <!-- ~~~~~ New section ~~~~~ -->
377 <sect2 id="installation-keepupdated"><title>Keeping your Installation Up-to-Date</title>
380 If you wish to receive an email notification whenever we release updates of
381 <application>Privoxy</application> or the actions file, <ulink
382 url="http://lists.sourceforge.net/lists/listinfo/ijbswa-announce/">subscribe
383 to our announce mailing list</ulink>, ijbswa-announce@lists.sourceforge.net.
387 In order not to lose your personal changes and adjustments when updating
388 to the latest <literal>default.action</literal> file we <emphasis>strongly
389 recommend</emphasis> that you use <literal>user.action</literal> and
390 <literal>user.filter</literal> for your local
391 customizations of <application>Privoxy</application>. See the <link
392 linkend="actions-file">Chapter on actions files</link> for details.
400 <!-- ~ End section ~ -->
402 <!-- ~~~~~ New section ~~~~~ -->
403 <sect1 id="whatsnew">
404 <title>What's New in this Release</title>
408 <!-- ~~~~~ New section ~~~~~ -->
410 <sect2 id="upgradersnote">
411 <title>Note to Upgraders</title>
414 A quick list of things to be aware of before upgrading from earlier
415 versions of <application>Privoxy</application>:
423 The recommended way to upgrade &my-app; is to backup your old
424 configuration files, install the new ones, verify that &my-app;
425 is working correctly and finally merge back your changes using
426 <application>diff</application> and maybe <application>patch</application>.
429 There are a number of new features in each &my-app; release and
430 most of them have to be explicitly enabled in the configuration
431 files. Old configuration files obviously don't do that and due
432 to syntax changes using old configuration files with a new
433 &my-app; isn't always possible anyway.
438 Note that some installers remove earlier versions completely,
439 including configuration files, therefore you should really save
440 any important configuration files!
445 On the other hand, other installers don't overwrite existing configuration
446 files, thinking you will want to do that yourself.
451 In the default configuration only fatal errors are logged now.
452 You can change that in the <link linkend="DEBUG">debug section</link>
453 of the configuration file. You may also want to enable more verbose
454 logging until you verified that the new &my-app; version is working
461 Three other config file settings are now off by default:
462 <link linkend="enable-remote-toggle">enable-remote-toggle</link>,
463 <link linkend="enable-remote-http-toggle">enable-remote-http-toggle</link>,
464 and <link linkend="enable-edit-actions">enable-edit-actions</link>.
465 If you use or want these, you will need to explicitly enable them, and
466 be aware of the security issues involved.
473 What constitutes a <quote>default</quote> configuration has changed,
474 and you may want to review which actions are <quote>on</quote> by
475 default. This is primarily a matter of emphasis, but some features
476 you may have been used to, may now be <quote>off</quote> by default.
477 There are also a number of new actions and filters you may want to
478 consider, most of which are not fully incorporated into the default
479 settings as yet (see above).
486 The default actions setting is now <literal>Cautious</literal>. Previous
487 releases had a default setting of <literal>Medium</literal>. Experienced
488 users may want to adjust this, as it is fairly conservative by &my-app;
489 standards and past practices. See <ulink
490 url="http://config.privoxy.org/edit-actions-list?f=default">
491 http://config.privoxy.org/edit-actions-list?f=default</ulink>. New users
492 should try the default settings for a while before turning up the volume.
498 The default setting has filtering turned <emphasis>off</emphasis>, which
499 subsequently means that compression is <emphasis>on</emphasis>. Remember
500 that filtering does not work on compressed pages, so if you use, or want to
501 use, filtering, you will need to force compression off. Example:
505 { +<link linkend="filter">filter</link>{google} +<link linkend="prevent-compression">prevent-compression</link> }
509 Or if you use a number of filters, or filter many sites, you may just want
510 to turn off compression for all sites in
511 <filename>default.action</filename> (or
512 <filename>user.action</filename>).
519 Also, <link linkend="SESSION-COOKIES-ONLY">session-cookies-only</link> is
520 off by default now. If you've liked this feature in the past, you may want
521 to turn it back on in <filename>user.action</filename> now.
528 Some installers may not automatically start
529 <application>Privoxy</application> after installation.
540 <!-- ~~~~~ New section ~~~~~ -->
541 <sect1 id="quickstart"><title>Quickstart to Using Privoxy</title>
547 Install <application>Privoxy</application>. See the <link
548 linkend="installation">Installation Section</link> below for platform specific
555 Advanced users and those who want to offer <application>Privoxy</application>
556 service to more than just their local machine should check the <link
557 linkend="config">main config file</link>, especially the <link
558 linkend="access-control">security-relevant</link> options. These are
565 Start <application>Privoxy</application>, if the installation program has
566 not done this already (may vary according to platform). See the section
567 <link linkend="startup">Starting <application>Privoxy</application></link>.
573 Set your browser to use <application>Privoxy</application> as HTTP and
574 HTTPS (SSL) <ulink url="http://en.wikipedia.org/wiki/Proxy_server">proxy</ulink>
575 by setting the proxy configuration for address of
576 <literal>127.0.0.1</literal> and port <literal>8118</literal>.
577 <emphasis>DO NOT</emphasis> activate proxying for <literal>FTP</literal> or
578 any protocols besides HTTP and HTTPS (SSL) unless you intend to prevent your
579 browser from using these protocols.
585 Flush your browser's disk and memory caches, to remove any cached ad images.
586 If using <application>Privoxy</application> to manage
587 <ulink url="http://en.wikipedia.org/wiki/Browser_cookie">cookies</ulink>,
588 you should remove any currently stored cookies too.
594 A default installation should provide a reasonable starting point for
595 most. There will undoubtedly be occasions where you will want to adjust the
596 configuration, but that can be dealt with as the need arises. Little
597 to no initial configuration is required in most cases, you may want
599 <ulink url="config.html#ENABLE-EDIT-ACTIONS">web-based action editor</ulink> though.
600 Be sure to read the warnings first.
603 See the <link linkend="configuration">Configuration section</link> for more
604 configuration options, and how to customize your installation.
605 You might also want to look at the <link
606 linkend="quickstart-ad-blocking">next section</link> for a quick
607 introduction to how <application>Privoxy</application> blocks ads and
614 If you experience ads that slip through, innocent images that are
615 blocked, or otherwise feel the need to fine-tune
616 <application>Privoxy's</application> behavior, take a look at the <link
617 linkend="actions-file">actions files</link>. As a quick start, you might
618 find the <link linkend="act-examples">richly commented examples</link>
619 helpful. You can also view and edit the actions files through the <ulink
620 url="http://config.privoxy.org">web-based user interface</ulink>. The
621 Appendix <quote><link linkend="actionsanat">Troubleshooting: Anatomy of an
622 Action</link></quote> has hints on how to understand and debug actions that
623 <quote>misbehave</quote>.
629 Please see the section <link linkend="contact">Contacting the
630 Developers</link> on how to report bugs, problems with websites or to get
637 Now enjoy surfing with enhanced control, comfort and privacy!
645 <!-- ~~~~~ New section ~~~~~ -->
647 <sect2 id="quickstart-ad-blocking">
648 <title>Quickstart to Ad Blocking</title>
650 NOTE: This section is deliberately redundant for those that don't
651 want to read the whole thing (which is getting lengthy).
654 Ad blocking is but one of <application>Privoxy's</application>
655 array of features. Many of these features are for the technically minded advanced
656 user. But, ad and banner blocking is surely common ground for everybody.
659 This section will provide a quick summary of ad blocking so
660 you can get up to speed quickly without having to read the more extensive
661 information provided below, though this is highly recommended.
664 First a bit of a warning ... blocking ads is much like blocking SPAM: the
665 more aggressive you are about it, the more likely you are to block
666 things that were not intended. And the more likely that some things
667 may not work as intended. So there is a trade off here. If you want
668 extreme ad free browsing, be prepared to deal with more
669 <quote>problem</quote> sites, and to spend more time adjusting the
670 configuration to solve these unintended consequences. In short, there is
671 not an easy way to eliminate <emphasis>all</emphasis> ads. Either take
672 the easy way and settle for <emphasis>most</emphasis> ads blocked with the
673 default configuration, or jump in and tweak it for your personal surfing
674 habits and preferences.
677 Secondly, a brief explanation of <application>Privoxy's </application>
678 <quote>actions</quote>. <quote>Actions</quote> in this context, are
679 the directives we use to tell <application>Privoxy</application> to perform
680 some task relating to HTTP transactions (i.e. web browsing). We tell
681 <application>Privoxy</application> to take some <quote>action</quote>. Each
682 action has a unique name and function. While there are many potential
683 <application>actions</application> in <application>Privoxy's</application>
684 arsenal, only a few are used for ad blocking. <link
685 linkend="actions">Actions</link>, and <link linkend="actions-file">action
686 configuration files</link>, are explained in depth below.
689 Actions are specified in <application>Privoxy's</application> configuration,
690 followed by one or more URLs to which the action should apply. URLs
691 can actually be URL type <link linkend="af-patterns">patterns</link> that use
692 wildcards so they can apply potentially to a range of similar URLs. The
693 actions, together with the URL patterns are called a section.
696 When you connect to a website, the full URL will either match one or more
697 of the sections as defined in <application>Privoxy's</application> configuration,
698 or not. If so, then <application>Privoxy</application> will perform the
699 respective actions. If not, then nothing special happens. Furthermore, web
700 pages may contain embedded, secondary URLs that your web browser will
701 use to load additional components of the page, as it parses the
702 original page's HTML content. An ad image for instance, is just an URL
703 embedded in the page somewhere. The image itself may be on the same server,
704 or a server somewhere else on the Internet. Complex web pages will have many
705 such embedded URLs. &my-app; can deal with each URL individually, so, for
706 instance, the main page text is not touched, but images from such-and-such
711 The most important actions for basic ad blocking are: <literal><link
712 linkend="block">block</link></literal>, <literal><link
713 linkend="handle-as-image">handle-as-image</link></literal>,
715 linkend="handle-as-empty-document">handle-as-empty-document</link></literal>,and
716 <literal><link linkend="set-image-blocker">set-image-blocker</link></literal>:
724 <literal><link linkend="block">block</link></literal> - this is perhaps
725 the single most used action, and is particularly important for ad blocking.
726 This action stops any contact between your browser and any URL patterns
727 that match this action's configuration. It can be used for blocking ads,
728 but also anything that is determined to be unwanted. By itself, it simply
729 stops any communication with the remote server and sends
730 <application>Privoxy</application>'s own built-in BLOCKED page instead to
731 let you now what has happened (with some exceptions, see below).
737 <literal><link linkend="handle-as-image">handle-as-image</link></literal> -
738 tells <application>Privoxy</application> to treat this URL as an image.
739 <application>Privoxy</application>'s default configuration already does this
740 for all common image types (e.g. GIF), but there are many situations where this
741 is not so easy to determine. So we'll force it in these cases. This is particularly
742 important for ad blocking, since only if we know that it's an image of
743 some kind, can we replace it with an image of our choosing, instead of the
744 <application>Privoxy</application> BLOCKED page (which would only result in
745 a <quote>broken image</quote> icon). There are some limitations to this
746 though. For instance, you can't just brute-force an image substitution for
747 an entire HTML page in most situations.
753 <literal><link linkend="handle-as-empty-document">handle-as-empty-document</link></literal> -
754 sends an empty document instead of <application>Privoxy's</application>
755 normal BLOCKED HTML page. This is useful for file types that are neither
756 HTML nor images, such as blocking JavaScript files.
763 linkend="set-image-blocker">set-image-blocker</link></literal> - tells
764 <application>Privoxy</application> what to display in place of an ad image that
765 has hit a block rule. For this to come into play, the URL must match a
766 <literal><link linkend="block">block</link></literal> action somewhere in the
767 configuration, <emphasis>and</emphasis>, it must also match an
768 <literal><link linkend="handle-as-image">handle-as-image</link></literal> action.
771 The configuration options on what to display instead of the ad are:
775 <emphasis>pattern</emphasis> - a checkerboard pattern, so that an ad
776 replacement is obvious. This is the default.
781 <emphasis>blank</emphasis> - A very small empty GIF image is displayed.
782 This is the so-called <quote>invisible</quote> configuration option.
787 <emphasis>http://<URL></emphasis> - A redirect to any image anywhere
788 of the user's choosing (advanced usage).
797 Advanced users will eventually want to explore &my-app;
798 <literal><link linkend="filter">filters</link></literal> as well. Filters
799 are very different from <literal><link
800 linkend="block">blocks</link></literal>.
801 A <quote>block</quote> blocks a site, page, or unwanted contented. Filters
802 are a way of filtering or modifying what is actually on the page. An example
803 filter usage: a text replacement of <quote>no-no</quote> for
804 <quote>nasty-word</quote>. That is a very simple example. This process can be
805 used for ad blocking, but it is more in the realm of advanced usage and has
806 some pitfalls to be wary off.
810 The quickest way to adjust any of these settings is with your browser through
811 the special <application>Privoxy</application> editor at <ulink
812 url="http://config.privoxy.org/show-status">http://config.privoxy.org/show-status</ulink>
813 (shortcut: <ulink url="http://p.p/">http://p.p/show-status</ulink>). This
814 is an internal page, and does not require Internet access.
818 Note that as of <application>Privoxy</application> 3.0.7 beta the
819 action editor is disabled by default. Check the
820 <ulink url="config.html#ENABLE-EDIT-ACTIONS">enable-edit-actions
821 section in the configuration file</ulink> to learn why and in which
822 cases it's safe to enable again.
826 If you decided to enable the action editor, select the appropriate
827 <quote>actions</quote> file, and click
828 <quote><guibutton>Edit</guibutton></quote>. It is best to put personal or
829 local preferences in <filename>user.action</filename> since this is not
830 meant to be overwritten during upgrades, and will over-ride the settings in
831 other files. Here you can insert new <quote>actions</quote>, and URLs for ad
832 blocking or other purposes, and make other adjustments to the configuration.
833 <application>Privoxy</application> will detect these changes automatically.
837 A quick and simple step by step example:
845 Right click on the ad image to be blocked, then select
846 <quote><guimenuitem>Copy Link Location</guimenuitem></quote> from the
854 url="http://config.privoxy.org/show-status">http://config.privoxy.org/show-status</ulink>
859 Find <filename>user.action</filename> in the top section, and click
860 on <quote><guibutton>Edit</guibutton></quote>:
863 <!-- image of editor and actions files selections -->
865 <figure pgwide="0" float="0"><title>Actions Files in Use</title>
868 <imagedata fileref="files-in-use.jpg" format="jpg">
871 <phrase>[ Screenshot of Actions Files in Use ]</phrase>
880 You should have a section with only
881 <literal><link linkend="block">block</link></literal> listed under
882 <quote>Actions:</quote>.
883 If not, click a <quote><guibutton>Insert new section below</guibutton></quote>
884 button, and in the new section that just appeared, click the
885 <guibutton>Edit</guibutton> button right under the word <quote>Actions:</quote>.
886 This will bring up a list of all actions. Find
887 <literal><link linkend="block">block</link></literal> near the top, and click
888 in the <quote>Enabled</quote> column, then <quote><guibutton>Submit</guibutton></quote>
894 Now, in the <literal><link linkend="block">block</link></literal> actions section,
895 click the <quote><guibutton>Add</guibutton></quote> button, and paste the URL the
896 browser got from <quote><guimenuitem>Copy Link Location</guimenuitem></quote>.
897 Remove the <literal>http://</literal> at the beginning of the URL. Then, click
898 <quote><guibutton>Submit</guibutton></quote> (or
899 <quote><guibutton>OK</guibutton></quote> if in a pop-up window).
904 Now go back to the original page, and press <keycap>SHIFT-Reload</keycap>
905 (or flush all browser caches). The image should be gone now.
913 This is a very crude and simple example. There might be good reasons to use a
914 wildcard pattern match to include potentially similar images from the same
915 site. For a more extensive explanation of <quote>patterns</quote>, and
916 the entire actions concept, see <link linkend="actions-file">the Actions
921 For advanced users who want to hand edit their config files, you might want
922 to now go to the <link linkend="act-examples">Actions Files Tutorial</link>.
923 The ideas explained therein also apply to the web-based editor.
926 There are also various
927 <link linkend="filter">filters</link> that can be used for ad blocking
928 (filters are a special subset of actions). These
929 fall into the <quote>advanced</quote> usage category, and are explained in
930 depth in later sections.
937 <!-- ~ End section ~ -->
940 <!-- ~~~~~ New section ~~~~~ -->
942 <title>Starting Privoxy</title>
944 Before launching <application>Privoxy</application> for the first time, you
945 will want to configure your browser(s) to use
946 <application>Privoxy</application> as a HTTP and HTTPS (SSL)
947 <ulink url="http://en.wikipedia.org/wiki/Proxy_server">proxy</ulink>. The default is
948 127.0.0.1 (or localhost) for the proxy address, and port 8118 (earlier versions
949 used port 8000). This is the one configuration step <emphasis>that must be done
953 Please note that <application>Privoxy</application> can only proxy HTTP and
954 HTTPS traffic. It will not work with FTP or other protocols.
957 <!-- image of Mozilla Proxy configuration -->
959 <figure pgwide="0" float="0"><title>Proxy Configuration Showing
960 Mozilla/Netscape HTTP and HTTPS (SSL) Settings</title>
963 <imagedata fileref="proxy_setup.jpg" format="jpg">
966 <phrase>[ Screenshot of Mozilla Proxy Configuration ]</phrase>
974 With <application>Firefox</application>, this is typically set under:
978 <guibutton>Tools</guibutton> -> <guibutton>Options</guibutton> -> <guibutton>Advanced</guibutton> -> <guibutton>Network</guibutton> -><guibutton>Connection</guibutton> -> <guibutton>Settings</guibutton>
983 Or optionally on some platforms:
987 <guibutton>Edit</guibutton> -> <guibutton>Preferences</guibutton> -> <guibutton>General</guibutton> -> <guibutton>Connection Settings</guibutton> -> <guibutton>Manual Proxy Configuration</guibutton>
993 With <application>Netscape</application> (and
994 <application>Mozilla</application>), this can be set under:
999 <!-- Mix ascii and gui art, something for everybody -->
1000 <!-- spacing on this is tricky -->
1001 <guibutton>Edit</guibutton> -> <guibutton>Preferences</guibutton> -> <guibutton>Advanced</guibutton> -> <guibutton>Proxies</guibutton> -> <guibutton>HTTP Proxy</guibutton>
1006 For <application>Internet Explorer v.5-7</application>:
1010 <guibutton>Tools</guibutton> -> <guibutton>Internet Options</guibutton> -> <guibutton>Connections</guibutton> -> <guibutton>LAN Settings</guibutton>
1014 Then, check <quote>Use Proxy</quote> and fill in the appropriate info
1015 (Address: 127.0.0.1, Port: 8118). Include HTTPS (SSL), if you want HTTPS
1016 proxy support too (sometimes labeled <quote>Secure</quote>). Make sure any
1017 checkboxes like <quote>Use the same proxy server for all protocols</quote> is
1018 <emphasis>UNCHECKED</emphasis>. You want only HTTP and HTTPS (SSL)!
1021 <!-- image of IE Proxy configuration -->
1023 <figure pgwide="0" float="0"><title>Proxy Configuration Showing
1024 Internet Explorer HTTP and HTTPS (Secure) Settings</title>
1027 <imagedata fileref="proxy2.jpg" format="jpg">
1030 <phrase>[ Screenshot of IE Proxy Configuration ]</phrase>
1038 After doing this, flush your browser's disk and memory caches to force a
1039 re-reading of all pages and to get rid of any ads that may be cached. Remove
1040 any <ulink url="http://en.wikipedia.org/wiki/Browser_cookie">cookies</ulink>,
1041 if you want <application>Privoxy</application> to manage that. You are now
1042 ready to start enjoying the benefits of using
1043 <application>Privoxy</application>!
1047 <application>Privoxy</application> itself is typically started by specifying the
1048 main configuration file to be used on the command line. If no configuration
1049 file is specified on the command line, <application>Privoxy</application>
1050 will look for a file named <filename>config</filename> in the current
1051 directory. Except on Win32 where it will try <filename>config.txt</filename>.
1054 <sect2 id="start-debian">
1055 <title>Debian</title>
1057 We use a script. Note that Debian typically starts &my-app; upon booting per
1058 default. It will use the file
1059 <filename>/etc/privoxy/config</filename> as its main configuration
1064 # /etc/init.d/privoxy start
1069 <sect2 id="start-freebsd">
1070 <title>FreeBSD and ElectroBSD</title>
1072 To start <application>Privoxy</application> upon booting, add
1073 "privoxy_enable='YES'" to <filename>/etc/rc.conf</filename>.
1074 <application>Privoxy</application> will use
1075 <filename>/usr/local/etc/privoxy/config</filename> as its main
1079 If you installed <application>Privoxy</application> into a jail, the
1080 paths above are relative to the jail root.
1083 To start <application>Privoxy</application> manually, run:
1087 # service privoxy onestart
1092 <sect2 id="start-windows">
1093 <title>Windows</title>
1095 Click on the &my-app; Icon to start <application>Privoxy</application>. If no configuration file is
1096 specified on the command line, <application>Privoxy</application> will look
1097 for a file named <filename>config.txt</filename>. Note that Windows will
1098 automatically start &my-app; when the system starts if you chose that option
1102 <application>Privoxy</application> can run with full Windows service functionality.
1103 On Windows only, the &my-app; program has two new command line arguments
1104 to install and uninstall &my-app; as a service. See the
1105 <link linkend="installation-pack-win">Windows Installation
1106 instructions</link> for details.
1110 <sect2 id="start-unices">
1111 <title>Solaris, NetBSD, HP-UX and others</title>
1113 Example Unix startup command:
1117 # /usr/sbin/privoxy /etc/privoxy/config
1122 <sect2 id="start-os2">
1125 During installation, <application>Privoxy</application> is configured to
1126 start automatically when the system restarts. You can start it manually by
1127 double-clicking on the <application>Privoxy</application> icon in the
1128 <application>Privoxy</application> folder.
1132 <sect2 id="start-macosx">
1133 <title>Mac OS X</title>
1135 After downloading the privoxy software, unzip the downloaded file by
1136 double-clicking on the zip file icon. Then, double-click on the
1137 installer package icon and follow the installation process.
1140 The privoxy service will automatically start after a successful
1141 installation. In addition, the privoxy service will automatically
1142 start every time your computer starts up.
1145 To prevent the privoxy service from automatically starting when your
1146 computer starts up, remove or rename the folder named
1147 /Library/StartupItems/Privoxy.
1150 A simple application named Privoxy Utility has been created which
1151 enables administrators to easily start and stop the privoxy service.
1154 In addition, the Privoxy Utility presents a simple way for
1155 administrators to edit the various privoxy config files. A method
1156 to uninstall the software is also available.
1159 An administrator username and password must be supplied in order for
1160 the Privoxy Utility to perform any of the tasks.
1168 See the section <link linkend="cmdoptions">Command line options</link> for
1172 must find a better place for this paragraph
1175 The included default configuration files should give a reasonable starting
1176 point. Most of the per site configuration is done in the
1177 <ulink url="actions-file.html"><quote>actions</quote></ulink> files. These are
1178 where various cookie actions are defined, ad and banner blocking, and other
1179 aspects of <application>Privoxy</application> configuration. There are several
1180 such files included, with varying levels of aggressiveness.
1184 You will probably want to keep an eye out for sites for which you may prefer
1185 persistent cookies, and add these to your actions configuration as needed. By
1186 default, most of these will be accepted only during the current browser
1187 session (aka <quote>session cookies</quote>), unless you add them to the
1188 configuration. If you want the browser to handle this instead, you will need
1189 to edit <filename>user.action</filename> (or through the web based interface)
1190 and disable this feature. If you use more than one browser, it would make
1191 more sense to let <application>Privoxy</application> handle this. In which
1192 case, the browser(s) should be set to accept all cookies.
1196 Another feature where you will probably want to define exceptions for trusted
1197 sites is the popup-killing (through <ulink
1198 url="actions-file.html#FILTER-POPUPS"><quote>+filter{popups}</quote></ulink>),
1199 because your favorite shopping, banking, or leisure site may need
1200 popups (explained below).
1204 <application>Privoxy</application> does not support all of the optional HTTP/1.1
1205 features yet. In the unlikely event that you experience inexplicable problems
1206 with browsers that use HTTP/1.1 per default
1207 (like <application>Mozilla</application> or recent versions of I.E.), you might
1208 try to force HTTP/1.0 compatibility. For Mozilla, look under <literal>Edit ->
1209 Preferences -> Debug -> Networking</literal>.
1210 Alternatively, set the <quote>+downgrade-http-version</quote> config option in
1211 <filename>default.action</filename> which will downgrade your browser's HTTP
1212 requests from HTTP/1.1 to HTTP/1.0 before processing them.
1216 After running <application>Privoxy</application> for a while, you can
1217 start to fine tune the configuration to suit your personal, or site,
1218 preferences and requirements. There are many, many aspects that can
1219 be customized. <quote>Actions</quote>
1220 can be adjusted by pointing your browser to
1221 <ulink url="http://config.privoxy.org/">http://config.privoxy.org/</ulink>
1222 (shortcut: <ulink url="http://p.p/">http://p.p/</ulink>),
1223 and then follow the link to <quote>View & Change the Current Configuration</quote>.
1224 (This is an internal page and does not require Internet access.)
1228 In fact, various aspects of <application>Privoxy</application>
1229 configuration can be viewed from this page, including
1230 current configuration parameters, source code version numbers,
1231 the browser's request headers, and <quote>actions</quote> that apply
1232 to a given URL. In addition to the actions file
1233 editor mentioned above, <application>Privoxy</application> can also
1234 be turned <quote>on</quote> and <quote>off</quote> (toggled) from this page.
1238 If you encounter problems, try loading the page without
1239 <application>Privoxy</application>. If that helps, enter the URL where
1240 you have the problems into <ulink url="http://p.p/show-url-info">the browser
1241 based rule tracing utility</ulink>. See which rules apply and why, and
1242 then try turning them off for that site one after the other, until the problem
1243 is gone. When you have found the culprit, you might want to turn the rest on
1248 If the above paragraph sounds gibberish to you, you might want to <link
1249 linkend="actions-file">read more about the actions concept</link>
1250 or even dive deep into the <link linkend="actionsanat">Appendix
1255 If you can't get rid of the problem at all, think you've found a bug in
1256 Privoxy, want to propose a new feature or smarter rules, please see the
1257 section <link linkend="contact"><quote>Contacting the
1258 Developers</quote></link> below.
1263 <!-- ~~~~~ New section ~~~~~ -->
1264 <sect2 id="cmdoptions">
1265 <title>Command Line Options</title>
1267 <application>Privoxy</application> may be invoked with the following
1268 command-line options:
1276 <emphasis>--config-test</emphasis>
1279 Exit after loading the configuration files before binding to
1280 the listen address. The exit code signals whether or not the
1281 configuration files have been successfully loaded.
1284 If the exit code is 1, at least one of the configuration files
1285 is invalid, if it is 0, all the configuration files have been
1286 successfully loaded (but may still contain errors that can
1287 currently only be detected at run time).
1290 This option doesn't affect the log setting, combination with
1291 <emphasis>--no-daemon</emphasis> is recommended if a configured
1292 log file shouldn't be used.
1297 <emphasis>--version</emphasis>
1300 Print version info and exit. Unix only.
1305 <emphasis>--help</emphasis>
1308 Print short usage info and exit. Unix only.
1313 <emphasis>--no-daemon</emphasis>
1316 Don't become a daemon, i.e. don't fork and become process group
1317 leader, and don't detach from controlling tty. Unix only.
1322 <emphasis>--pidfile FILE</emphasis>
1325 On startup, write the process ID to <emphasis>FILE</emphasis>. Delete the
1326 <emphasis>FILE</emphasis> on exit. Failure to create or delete the
1327 <emphasis>FILE</emphasis> is non-fatal. If no <emphasis>FILE</emphasis>
1328 option is given, no PID file will be used. Unix only.
1333 <emphasis>--user USER[.GROUP]</emphasis>
1336 After (optionally) writing the PID file, assume the user ID of
1337 <emphasis>USER</emphasis>, and if included the GID of GROUP. Exit if the
1338 privileges are not sufficient to do so. Unix only.
1343 <emphasis>--chroot</emphasis>
1346 Before changing to the user ID given in the <emphasis>--user</emphasis> option,
1347 chroot to that user's home directory, i.e. make the kernel pretend to the &my-app;
1348 process that the directory tree starts there. If set up carefully, this can limit
1349 the impact of possible vulnerabilities in &my-app; to the files contained in that hierarchy.
1355 <emphasis>--pre-chroot-nslookup hostname</emphasis>
1358 Specifies a hostname (for example www.privoxy.org) to look up before doing a chroot.
1359 On some systems, initializing the resolver library involves reading config files from
1360 /etc and/or loading additional shared libraries from /lib.
1361 On these systems, doing a hostname lookup before the chroot reduces
1362 the number of files that must be copied into the chroot tree.
1365 For fastest startup speed, a good value is a hostname that is not in /etc/hosts but that
1366 your local name server (listed in /etc/resolv.conf) can resolve without recursion
1367 (that is, without having to ask any other name servers). The hostname need not exist,
1368 but if it doesn't, an error message (which can be ignored) will be output.
1374 <emphasis>configfile</emphasis>
1377 If no <emphasis>configfile</emphasis> is included on the command line,
1378 <application>Privoxy</application> will look for a file named
1379 <quote>config</quote> in the current directory (except on Win32
1380 where it will look for <quote>config.txt</quote> instead). Specify
1381 full path to avoid confusion. If no config file is found,
1382 <application>Privoxy</application> will fail to start.
1390 On <application>MS Windows</application> only there are two additional
1391 command-line options to allow <application>Privoxy</application> to install and
1392 run as a <emphasis>service</emphasis>. See the
1393 <link linkend="installation-pack-win">Window Installation section</link>
1401 <!-- ~ End section ~ -->
1404 <!-- ~~~~~ New section ~~~~~ -->
1405 <sect1 id="configuration"><title>Privoxy Configuration</title>
1407 All <application>Privoxy</application> configuration is stored
1408 in text files. These files can be edited with a text editor.
1409 Many important aspects of <application>Privoxy</application> can
1410 also be controlled easily with a web browser.
1414 <!-- ~~~~~ New section ~~~~~ -->
1417 <title>Controlling Privoxy with Your Web Browser</title>
1419 <application>Privoxy</application>'s user interface can be reached through the special
1420 URL <ulink url="http://config.privoxy.org/">http://config.privoxy.org/</ulink>
1421 (shortcut: <ulink url="http://p.p/">http://p.p/</ulink>),
1422 which is a built-in page and works without Internet access.
1423 You will see the following section:
1427 <!-- Needs to be put in a table and colorized -->
1430 <bridgehead renderas="sect2"> Privoxy Menu</bridgehead>
1434 ▪ <ulink url="http://config.privoxy.org/show-status">View & change the current configuration</ulink>
1437 ▪ <ulink url="http://config.privoxy.org/show-version">View the source code version numbers</ulink>
1440 ▪ <ulink url="http://config.privoxy.org/show-request">View the request headers.</ulink>
1443 ▪ <ulink url="http://config.privoxy.org/show-url-info">Look up which actions apply to a URL and why</ulink>
1446 ▪ <ulink url="http://config.privoxy.org/toggle">Toggle Privoxy on or off</ulink>
1449 ▪ <ulink
1450 url="http://www.privoxy.org/&p-version;/user-manual/">Documentation</ulink>
1458 This should be self-explanatory. Note the first item leads to an editor for the
1459 <link linkend="actions-file">actions files</link>, which is where the ad, banner,
1460 cookie, and URL blocking magic is configured as well as other advanced features of
1461 <application>Privoxy</application>. This is an easy way to adjust various
1462 aspects of <application>Privoxy</application> configuration. The actions
1463 file, and other configuration files, are explained in detail below.
1467 <quote>Toggle Privoxy On or Off</quote> is handy for sites that might
1468 have problems with your current actions and filters. You can in fact use
1469 it as a test to see whether it is <application>Privoxy</application>
1470 causing the problem or not. <application>Privoxy</application> continues
1471 to run as a proxy in this case, but all manipulation is disabled, i.e.
1472 <application>Privoxy</application> acts like a normal forwarding proxy.
1476 Note that several of the features described above are disabled by default
1477 in <application>Privoxy</application> 3.0.7 beta and later.
1479 <ulink url="config.html">configuration file</ulink> to learn why
1480 and in which cases it's safe to enable them again.
1485 <!-- ~ End section ~ -->
1490 <!-- ~~~~~ New section ~~~~~ -->
1492 <sect2 id="confoverview">
1493 <title>Configuration Files Overview</title>
1495 For Unix, *BSD and Linux, all configuration files are located in
1496 <filename>/etc/privoxy/</filename> by default. For MS Windows, OS/2, and
1497 AmigaOS these are all in the same directory as the
1498 <application>Privoxy</application> executable. <![%p-not-stable;[ The name
1499 and number of configuration files has changed from previous versions, and is
1500 subject to change as development progresses.]]>
1504 The installed defaults provide a reasonable starting point, though
1505 some settings may be aggressive by some standards. For the time being, the
1506 principle configuration files are:
1514 The <link linkend="config">main configuration file</link> is named <filename>config</filename>
1515 on Linux, Unix, BSD, OS/2, and AmigaOS and <filename>config.txt</filename>
1516 on Windows. This is a required file.
1522 <filename>match-all.action</filename> is used to define which <quote>actions</quote>
1523 relating to banner-blocking, images, pop-ups, content modification, cookie handling
1524 etc should be applied by default. It should be the first actions file loaded.
1527 <filename>default.action</filename> defines many exceptions (both positive and negative)
1528 from the default set of actions that's configured in <filename>match-all.action</filename>.
1529 It should be the second actions file loaded and shouldn't be edited by the user.
1532 Multiple actions files may be defined in <filename>config</filename>. These
1533 are processed in the order they are defined. Local customizations and locally
1534 preferred exceptions to the default policies as defined in
1535 <filename>match-all.action</filename> (which you will most probably want
1536 to define sooner or later) are best applied in <filename>user.action</filename>,
1537 where you can preserve them across upgrades. The file isn't installed by all
1538 installers, but you can easily create it yourself with a text editor.
1541 There is also a web based editor that can be accessed from
1543 url="http://config.privoxy.org/show-status">http://config.privoxy.org/show-status</ulink>
1545 url="http://p.p/show-status">http://p.p/show-status</ulink>) for the
1546 various actions files.
1552 <quote>Filter files</quote> (the <link linkend="filter-file">filter
1553 file</link>) can be used to re-write the raw page content, including
1554 viewable text as well as embedded HTML and JavaScript, and whatever else
1555 lurks on any given web page. The filtering jobs are only pre-defined here;
1556 whether to apply them or not is up to the actions files.
1557 <filename>default.filter</filename> includes various filters made
1558 available for use by the developers. Some are much more intrusive than
1559 others, and all should be used with caution. You may define additional
1560 filter files in <filename>config</filename> as you can with
1561 actions files. We suggest <filename>user.filter</filename> for any
1562 locally defined filters or customizations.
1570 The syntax of the configuration and filter files may change between different
1571 Privoxy versions, unfortunately some enhancements cost backwards compatibility.
1572 <!-- Add link to documentation-->
1576 All files use the <quote><literal>#</literal></quote> character to denote a
1577 comment (the rest of the line will be ignored) and understand line continuation
1578 through placing a backslash ("<literal>\</literal>") as the very last character
1579 in a line. If the <literal>#</literal> is preceded by a backslash, it looses
1580 its special function. Placing a <literal>#</literal> in front of an otherwise
1581 valid configuration line to prevent it from being interpreted is called "commenting
1582 out" that line. Blank lines are ignored.
1586 The actions files and filter files
1587 can use Perl style <link linkend="regex">regular expressions</link> for
1588 maximum flexibility.
1592 After making any changes, there is no need to restart
1593 <application>Privoxy</application> in order for the changes to take
1594 effect. <application>Privoxy</application> detects such changes
1595 automatically. Note, however, that it may take one or two additional
1596 requests for the change to take effect. When changing the listening address
1597 of <application>Privoxy</application>, these <quote>wake up</quote> requests
1598 must obviously be sent to the <emphasis>old</emphasis> listening address.
1603 While under development, the configuration content is subject to change.
1604 The below documentation may not be accurate by the time you read this.
1605 Also, what constitutes a <quote>default</quote> setting, may change, so
1606 please check all your configuration files on important issues.
1612 <!-- ~ End section ~ -->
1615 <!-- ~~~~~~~~ New section Header ~~~~~~~~~ -->
1617 <!-- **************************************************** -->
1618 <!-- Include config.sgml here -->
1619 <!-- This is where the entire config file is detailed. -->
1621 <!-- end include -->
1624 <!-- ~ End section ~ -->
1628 <!-- ~~~~~~~~ New section Header ~~~~~~~~~ -->
1630 <sect1 id="actions-file"><title>Actions Files</title>
1634 XXX: similar descriptions are in the Configuration Files sections.
1635 We should only describe them at one place.
1638 The actions files are used to define what <emphasis>actions</emphasis>
1639 <application>Privoxy</application> takes for which URLs, and thus determines
1640 how ad images, cookies and various other aspects of HTTP content and
1641 transactions are handled, and on which sites (or even parts thereof).
1642 There are a number of such actions, with a wide range of functionality.
1643 Each action does something a little different.
1644 These actions give us a veritable arsenal of tools with which to exert
1645 our control, preferences and independence. Actions can be combined so that
1646 their effects are aggregated when applied against a given set of URLs.
1650 are three action files included with <application>Privoxy</application> with
1657 <filename>match-all.action</filename> - is used to define which
1658 <quote>actions</quote> relating to banner-blocking, images, pop-ups,
1659 content modification, cookie handling etc should be applied by default.
1660 It should be the first actions file loaded
1665 <filename>default.action</filename> - defines many exceptions (both
1666 positive and negative) from the default set of actions that's configured
1667 in <filename>match-all.action</filename>. It is a set of rules that should
1668 work reasonably well as-is for most users. This file is only supposed to
1669 be edited by the developers. It should be the second actions file loaded.
1674 <filename>user.action</filename> - is intended to be for local site
1675 preferences and exceptions. As an example, if your ISP or your bank
1676 has specific requirements, and need special handling, this kind of
1677 thing should go here. This file will not be upgraded.
1682 <guibutton>Edit</guibutton> <guibutton>Set to Cautious</guibutton> <guibutton>Set to Medium</guibutton> <guibutton>Set to Advanced</guibutton>
1685 These have increasing levels of aggressiveness <emphasis>and have no
1686 influence on your browsing unless you select them explicitly in the
1687 editor</emphasis>. A default installation should be pre-set to
1688 <literal>Cautious</literal>. New users should try this for a while before
1689 adjusting the settings to more aggressive levels. The more aggressive
1690 the settings, then the more likelihood there is of problems such as sites
1691 not working as they should.
1694 The <guibutton>Edit</guibutton> button allows you to turn each
1695 action on/off individually for fine-tuning. The <guibutton>Cautious</guibutton>
1696 button changes the actions list to low/safe settings which will activate
1697 ad blocking and a minimal set of &my-app;'s features, and subsequently
1698 there will be less of a chance for accidental problems. The
1699 <guibutton>Medium</guibutton> button sets the list to a medium level of
1700 other features and a low level set of privacy features. The
1701 <guibutton>Advanced</guibutton> button sets the list to a high level of
1702 ad blocking and medium level of privacy. See the chart below. The latter
1703 three buttons over-ride any changes via with the
1704 <guibutton>Edit</guibutton> button. More fine-tuning can be done in the
1705 lower sections of this internal page.
1708 While the actions file editor allows to enable these settings in all
1709 actions files, they are only supposed to be enabled in the first one
1710 to make sure you don't unintentionally overrule earlier rules.
1713 The default profiles, and their associated actions, as pre-defined in
1714 <filename>default.action</filename> are:
1717 <table frame=all><title>Default Configurations</title>
1718 <tgroup cols=4 align=left colsep=1 rowsep=1>
1719 <colspec colname=c1>
1720 <colspec colname=c2>
1721 <colspec colname=c3>
1722 <colspec colname=c4>
1725 <entry>Feature</entry>
1726 <entry>Cautious</entry>
1727 <entry>Medium</entry>
1728 <entry>Advanced</entry>
1733 <!-- <entry>f1</entry> -->
1734 <!-- <entry>f2</entry> -->
1735 <!-- <entry>f3</entry> -->
1736 <!-- <entry>f4</entry> -->
1742 <entry>Ad-blocking Aggressiveness</entry>
1743 <entry>medium</entry>
1749 <entry>Ad-filtering by size</entry>
1756 <entry>Ad-filtering by link</entry>
1762 <entry>Pop-up killing</entry>
1763 <entry>blocks only</entry>
1764 <entry>blocks only</entry>
1765 <entry>blocks only</entry>
1769 <entry>Privacy Features</entry>
1771 <entry>medium</entry>
1772 <entry>medium/high</entry>
1776 <entry>Cookie handling</entry>
1778 <entry>session-only</entry>
1783 <entry>Referer forging</entry>
1790 <entry>GIF de-animation</entry>
1797 <entry>Fast redirects</entry>
1804 <entry>HTML taming</entry>
1811 <entry>JavaScript taming</entry>
1818 <entry>Web-bug killing</entry>
1825 <entry>Image tag reordering</entry>
1841 The list of actions files to be used are defined in the main configuration
1842 file, and are processed in the order they are defined (e.g.
1843 <filename>default.action</filename> is typically processed before
1844 <filename>user.action</filename>). The content of these can all be viewed and
1846 url="http://config.privoxy.org/show-status">http://config.privoxy.org/show-status</ulink>.
1847 The over-riding principle when applying actions, is that the last action that
1848 matches a given URL wins. The broadest, most general rules go first
1849 (defined in <filename>default.action</filename>),
1850 followed by any exceptions (typically also in
1851 <filename>default.action</filename>), which are then followed lastly by any
1852 local preferences (typically in <emphasis>user</emphasis><filename>.action</filename>).
1853 Generally, <filename>user.action</filename> has the last word.
1857 An actions file typically has multiple sections. If you want to use
1858 <quote>aliases</quote> in an actions file, you have to place the (optional)
1859 <link linkend="aliases">alias section</link> at the top of that file.
1860 Then comes the default set of rules which will apply universally to all
1861 sites and pages (be <emphasis>very careful</emphasis> with using such a
1862 universal set in <filename>user.action</filename> or any other actions file after
1863 <filename>default.action</filename>, because it will override the result
1864 from consulting any previous file). And then below that,
1865 exceptions to the defined universal policies. You can regard
1866 <filename>user.action</filename> as an appendix to <filename>default.action</filename>,
1867 with the advantage that it is a separate file, which makes preserving your
1868 personal settings across <application>Privoxy</application> upgrades easier.
1872 Actions can be used to block anything you want, including ads, banners, or
1873 just some obnoxious URL whose content you would rather not see. Cookies can be accepted
1874 or rejected, or accepted only during the current browser session (i.e. not
1875 written to disk), content can be modified, some JavaScripts tamed, user-tracking
1876 fooled, and much more. See below for a <link linkend="actions">complete list
1880 <!-- ~~~~~ New section ~~~~~ -->
1882 <title>Finding the Right Mix</title>
1884 Note that some <link linkend="actions">actions</link>, like cookie suppression
1885 or script disabling, may render some sites unusable that rely on these
1886 techniques to work properly. Finding the right mix of actions is not always easy and
1887 certainly a matter of personal taste. And, things can always change, requiring
1888 refinements in the configuration. In general, it can be said that the more
1889 <quote>aggressive</quote> your default settings (in the top section of the
1890 actions file) are, the more exceptions for <quote>trusted</quote> sites you
1891 will have to make later. If, for example, you want to crunch all cookies per
1892 default, you'll have to make exceptions from that rule for sites that you
1893 regularly use and that require cookies for actually useful purposes, like maybe
1894 your bank, favorite shop, or newspaper.
1898 We have tried to provide you with reasonable rules to start from in the
1899 distribution actions files. But there is no general rule of thumb on these
1900 things. There just are too many variables, and sites are constantly changing.
1901 Sooner or later you will want to change the rules (and read this chapter again :).
1905 <!-- ~~~~~ New section ~~~~~ -->
1907 <title>How to Edit</title>
1909 The easiest way to edit the actions files is with a browser by
1910 using our browser-based editor, which can be reached from <ulink
1911 url="http://config.privoxy.org/show-status">http://config.privoxy.org/show-status</ulink>.
1912 Note: the config file option <link
1913 linkend="enable-edit-actions">enable-edit-actions</link> must be enabled for
1914 this to work. The editor allows both fine-grained control over every single
1915 feature on a per-URL basis, and easy choosing from wholesale sets of defaults
1916 like <quote>Cautious</quote>, <quote>Medium</quote> or
1917 <quote>Advanced</quote>. Warning: the <quote>Advanced</quote> setting is more
1918 aggressive, and will be more likely to cause problems for some sites.
1919 Experienced users only!
1923 If you prefer plain text editing to GUIs, you can of course also directly edit the
1924 the actions files with your favorite text editor. Look at
1925 <filename>default.action</filename> which is richly commented with many
1931 <sect2 id="actions-apply">
1932 <title>How Actions are Applied to Requests</title>
1934 Actions files are divided into sections. There are special sections,
1935 like the <quote><link linkend="aliases">alias</link></quote> sections which will
1936 be discussed later. For now let's concentrate on regular sections: They have a
1937 heading line (often split up to multiple lines for readability) which consist
1938 of a list of actions, separated by whitespace and enclosed in curly braces.
1939 Below that, there is a list of URL and tag patterns, each on a separate line.
1943 To determine which actions apply to a request, the URL of the request is
1944 compared to all URL patterns in each <quote>action file</quote>.
1945 Every time it matches, the list of applicable actions for the request is
1946 incrementally updated, using the heading of the section in which the
1947 pattern is located. The same is done again for tags and tag patterns later on.
1951 If multiple applying sections set the same action differently,
1952 the last match wins. If not, the effects are aggregated.
1953 E.g. a URL might match a regular section with a heading line of <literal>{
1954 +<link linkend="handle-as-image">handle-as-image</link> }</literal>,
1955 then later another one with just <literal>{
1956 +<link linkend="block">block</link> }</literal>, resulting
1957 in <emphasis>both</emphasis> actions to apply. And there may well be
1958 cases where you will want to combine actions together. Such a section then
1964 { +<literal>handle-as-image</literal> +<literal>block{Banner ads.}</literal> }
1965 # Block these as if they were images. Send no block page.
1967 media.example.com/.*banners
1968 .example.com/images/ads/</screen>
1972 You can trace this process for URL patterns and any given URL by visiting <ulink
1973 url="http://config.privoxy.org/show-url-info">http://config.privoxy.org/show-url-info</ulink>.
1977 Examples and more detail on this is provided in the Appendix, <link linkend="ACTIONSANAT">
1978 Troubleshooting: Anatomy of an Action</link> section.
1982 <!-- ~~~~~ New section ~~~~~ -->
1983 <sect2 id="af-patterns">
1984 <title>Patterns</title>
1986 As mentioned, <application>Privoxy</application> uses <quote>patterns</quote>
1987 to determine what <emphasis>actions</emphasis> might apply to which sites and
1988 pages your browser attempts to access. These <quote>patterns</quote> use wild
1989 card type <emphasis>pattern</emphasis> matching to achieve a high degree of
1990 flexibility. This allows one expression to be expanded and potentially match
1991 against many similar patterns.
1995 Generally, an URL pattern has the form
1996 <literal><host><port>/<path></literal>, where the
1997 <literal><host></literal>, the <literal><port></literal>
1998 and the <literal><path></literal> are optional. (This is why the special
1999 <literal>/</literal> pattern matches all URLs). Note that the protocol
2000 portion of the URL pattern (e.g. <literal>http://</literal>) should
2001 <emphasis>not</emphasis> be included in the pattern. This is assumed already!
2004 The pattern matching syntax is different for the host and path parts of
2005 the URL. The host part uses a simple globbing type matching technique,
2006 while the path part uses more flexible
2007 <ulink url="http://en.wikipedia.org/wiki/Regular_expressions"><quote>Regular
2008 Expressions</quote></ulink> (POSIX 1003.2).
2011 The port part of a pattern is a decimal port number preceded by a colon
2012 (<literal>:</literal>). If the host part contains a numerical IPv6 address,
2013 it has to be put into angle brackets
2014 (<literal><</literal>, <literal>></literal>).
2019 <term><literal>www.example.com/</literal></term>
2022 is a host-only pattern and will match any request to <literal>www.example.com</literal>,
2023 regardless of which document on that server is requested. So ALL pages in
2024 this domain would be covered by the scope of this action. Note that a
2025 simple <literal>example.com</literal> is different and would NOT match.
2030 <term><literal>www.example.com</literal></term>
2033 means exactly the same. For host-only patterns, the trailing <literal>/</literal> may
2039 <term><literal>www.example.com/index.html</literal></term>
2042 matches all the documents on <literal>www.example.com</literal>
2043 whose name starts with <literal>/index.html</literal>.
2048 <term><literal>www.example.com/index.html$</literal></term>
2051 matches only the single document <literal>/index.html</literal>
2052 on <literal>www.example.com</literal>.
2057 <term><literal>/index.html$</literal></term>
2060 matches the document <literal>/index.html</literal>, regardless of the domain,
2061 i.e. on <emphasis>any</emphasis> web server anywhere.
2066 <term><literal>/</literal></term>
2069 Matches any URL because there's no requirement for either the
2070 domain or the path to match anything.
2075 <term><literal>:8000/</literal></term>
2078 Matches any URL pointing to TCP port 8000.
2083 <term><literal>10.0.0.1/</literal></term>
2086 Matches any URL with the host address <literal>10.0.0.1</literal>.
2087 (Note that the real URL uses plain brackets, not angle brackets.)
2092 <term><literal><2001:db8::1>/</literal></term>
2095 Matches any URL with the host address <literal>2001:db8::1</literal>.
2096 (Note that the real URL uses plain brackets, not angle brackets.)
2101 <term><literal>index.html</literal></term>
2104 matches nothing, since it would be interpreted as a domain name and
2105 there is no top-level domain called <literal>.html</literal>. So its
2113 <!-- ~~~~~ New section ~~~~~ -->
2114 <sect3 id="host-pattern"><title>The Host Pattern</title>
2117 The matching of the host part offers some flexible options: if the
2118 host pattern starts or ends with a dot, it becomes unanchored at that end.
2119 The host pattern is often referred to as domain pattern as it is usually
2120 used to match domain names and not IP addresses.
2126 <term><literal>.example.com</literal></term>
2129 matches any domain with first-level domain <literal>com</literal>
2130 and second-level domain <literal>example</literal>.
2131 For example <literal>www.example.com</literal>,
2132 <literal>example.com</literal> and <literal>foo.bar.baz.example.com</literal>.
2133 Note that it wouldn't match if the second-level domain was <literal>another-example</literal>.
2138 <term><literal>www.</literal></term>
2141 matches any domain that <emphasis>STARTS</emphasis> with
2142 <literal>www.</literal> (It also matches the domain
2143 <literal>www</literal> but most of the time that doesn't matter.)
2148 <term><literal>.example.</literal></term>
2151 matches any domain that <emphasis>CONTAINS</emphasis> <literal>.example.</literal>.
2152 And, by the way, also included would be any files or documents that exist
2153 within that domain since no path limitations are specified. (Correctly
2154 speaking: It matches any FQDN that contains <literal>example</literal> as
2155 a domain.) This might be <literal>www.example.com</literal>,
2156 <literal>news.example.de</literal>, or
2157 <literal>www.example.net/cgi/testing.pl</literal> for instance. All these
2165 Additionally, there are wild-cards that you can use in the domain names
2166 themselves. These work similarly to shell globbing type wild-cards:
2167 <quote>*</quote> represents zero or more arbitrary characters (this is
2169 <ulink url="http://en.wikipedia.org/wiki/Regular_expressions"><quote>Regular
2170 Expression</quote></ulink> based syntax of <quote>.*</quote>),
2171 <quote>?</quote> represents any single character (this is equivalent to the
2172 regular expression syntax of a simple <quote>.</quote>), and you can define
2173 <quote>character classes</quote> in square brackets which is similar to
2174 the same regular expression technique. All of this can be freely mixed:
2179 <term><literal>ad*.example.com</literal></term>
2182 matches <quote>adserver.example.com</quote>,
2183 <quote>ads.example.com</quote>, etc but not <quote>sfads.example.com</quote>
2188 <term><literal>*ad*.example.com</literal></term>
2191 matches all of the above, and then some.
2196 <term><literal>.?pix.com</literal></term>
2199 matches <literal>www.ipix.com</literal>,
2200 <literal>pictures.epix.com</literal>, <literal>a.b.c.d.e.upix.com</literal> etc.
2205 <term><literal>www[1-9a-ez].example.c*</literal></term>
2208 matches <literal>www1.example.com</literal>,
2209 <literal>www4.example.cc</literal>, <literal>wwwd.example.cy</literal>,
2210 <literal>wwwz.example.com</literal> etc., but <emphasis>not</emphasis>
2211 <literal>wwww.example.com</literal>.
2218 While flexible, this is not the sophistication of full regular expression based syntax.
2223 <!-- ~ End section ~ -->
2226 <!-- ~~~~~ New section ~~~~~ -->
2227 <sect3><title>The Path Pattern</title>
2230 <application>Privoxy</application> uses <quote>modern</quote> POSIX 1003.2
2231 <ulink url="http://en.wikipedia.org/wiki/Regular_expressions"><quote>Regular
2232 Expressions</quote></ulink> for matching the path portion (after the slash),
2233 and is thus more flexible.
2237 There is an <link linkend="regex">Appendix</link> with a brief quick-start into regular
2238 expressions, you also might want to have a look at your operating system's documentation
2239 on regular expressions (try <literal>man re_format</literal>).
2243 Note that the path pattern is automatically left-anchored at the <quote>/</quote>,
2244 i.e. it matches as if it would start with a <quote>^</quote> (regular expression speak
2245 for the beginning of a line).
2249 Please also note that matching in the path is <emphasis>CASE INSENSITIVE</emphasis>
2250 by default, but you can switch to case sensitive at any point in the pattern by using the
2251 <quote>(?-i)</quote> switch: <literal>www.example.com/(?-i)PaTtErN.*</literal> will match
2252 only documents whose path starts with <literal>PaTtErN</literal> in
2253 <emphasis>exactly</emphasis> this capitalization.
2258 <term><literal>.example.com/.*</literal></term>
2261 Is equivalent to just <quote>.example.com</quote>, since any documents
2262 within that domain are matched with or without the <quote>.*</quote>
2263 regular expression. This is redundant
2268 <term><literal>.example.com/.*/index.html$</literal></term>
2271 Will match any page in the domain of <quote>example.com</quote> that is
2272 named <quote>index.html</quote>, and that is part of some path. For
2273 example, it matches <quote>www.example.com/testing/index.html</quote> but
2274 NOT <quote>www.example.com/index.html</quote> because the regular
2275 expression called for at least two <quote>/'s</quote>, thus the path
2276 requirement. It also would match
2277 <quote>www.example.com/testing/index_html</quote>, because of the
2278 special meta-character <quote>.</quote>.
2283 <term><literal>.example.com/(.*/)?index\.html$</literal></term>
2286 This regular expression is conditional so it will match any page
2287 named <quote>index.html</quote> regardless of path which in this case can
2288 have one or more <quote>/'s</quote>. And this one must contain exactly
2289 <quote>.html</quote> (but does not have to end with that!).
2294 <term><literal>.example.com/(.*/)(ads|banners?|junk)</literal></term>
2297 This regular expression will match any path of <quote>example.com</quote>
2298 that contains any of the words <quote>ads</quote>, <quote>banner</quote>,
2299 <quote>banners</quote> (because of the <quote>?</quote>) or <quote>junk</quote>.
2300 The path does not have to end in these words, just contain them.
2305 <term><literal>.example.com/(.*/)(ads|banners?|junk)/.*\.(jpe?g|gif|png)$</literal></term>
2308 This is very much the same as above, except now it must end in either
2309 <quote>.jpg</quote>, <quote>.jpeg</quote>, <quote>.gif</quote> or <quote>.png</quote>. So this
2310 one is limited to common image formats.
2317 There are many, many good examples to be found in <filename>default.action</filename>,
2318 and more tutorials below in <link linkend="regex">Appendix on regular expressions</link>.
2323 <!-- ~ End section ~ -->
2326 <!-- ~~~~~ New section ~~~~~ -->
2327 <sect3 id="tag-pattern"><title>The Tag Pattern</title>
2330 Tag patterns are used to change the applying actions based on the
2331 request's tags. Tags can be created with either the
2332 <link linkend="CLIENT-HEADER-TAGGER">client-header-tagger</link>
2333 or the <link linkend="SERVER-HEADER-TAGGER">server-header-tagger</link> action.
2337 Tag patterns have to start with <quote>TAG:</quote>, so &my-app;
2338 can tell them apart from URL patterns. Everything after the colon
2339 including white space, is interpreted as a regular expression with
2340 path pattern syntax, except that tag patterns aren't left-anchored
2341 automatically (&my-app; doesn't silently add a <quote>^</quote>,
2342 you have to do it yourself if you need it).
2346 To match all requests that are tagged with <quote>foo</quote>
2347 your pattern line should be <quote>TAG:^foo$</quote>,
2348 <quote>TAG:foo</quote> would work as well, but it would also
2349 match requests whose tags contain <quote>foo</quote> somewhere.
2350 <quote>TAG: foo</quote> wouldn't work as it requires white space.
2354 Sections can contain URL and tag patterns at the same time,
2355 but tag patterns are checked after the URL patterns and thus
2356 always overrule them, even if they are located before the URL patterns.
2360 Once a new tag is added, Privoxy checks right away if it's matched by one
2361 of the tag patterns and updates the action settings accordingly. As a result
2362 tags can be used to activate other tagger actions, as long as these other
2363 taggers look for headers that haven't already be parsed.
2367 For example you could tag client requests which use the
2368 <literal>POST</literal> method,
2369 then use this tag to activate another tagger that adds a tag if cookies
2370 are sent, and then use a block action based on the cookie tag. This allows
2371 the outcome of one action, to be input into a subsequent action. However if
2372 you'd reverse the position of the described taggers, and activated the
2373 method tagger based on the cookie tagger, no method tags would be created.
2374 The method tagger would look for the request line, but at the time
2375 the cookie tag is created, the request line has already been parsed.
2379 While this is a limitation you should be aware of, this kind of
2380 indirection is seldom needed anyway and even the example doesn't
2381 make too much sense.
2386 <!-- ~~~~~ New section ~~~~~ -->
2387 <sect3 id="negative-tag-patterns"><title>The Negative Tag Patterns</title>
2390 To match requests that do not have a certain tag, specify a negative tag pattern
2391 by prefixing the tag pattern line with either <quote>NO-REQUEST-TAG:</quote>
2392 or <quote>NO-RESPONSE-TAG:</quote> instead of <quote>TAG:</quote>.
2396 Negative tag patterns created with <quote>NO-REQUEST-TAG:</quote> are checked
2397 after all client headers are scanned, the ones created with <quote>NO-RESPONSE-TAG:</quote>
2398 are checked after all server headers are scanned. In both cases all the created
2399 tags are considered.
2405 <!-- ~ End section ~ -->
2408 <!-- ~~~~~ New section ~~~~~ -->
2410 <sect2 id="actions">
2411 <title>Actions</title>
2413 All actions are disabled by default, until they are explicitly enabled
2414 somewhere in an actions file. Actions are turned on if preceded with a
2415 <quote>+</quote>, and turned off if preceded with a <quote>-</quote>. So a
2416 <literal>+action</literal> means <quote>do that action</quote>, e.g.
2417 <literal>+block</literal> means <quote>please block URLs that match the
2418 following patterns</quote>, and <literal>-block</literal> means <quote>don't
2419 block URLs that match the following patterns, even if <literal>+block</literal>
2420 previously applied.</quote>
2425 Again, actions are invoked by placing them on a line, enclosed in curly braces and
2426 separated by whitespace, like in
2427 <literal>{+some-action -some-other-action{some-parameter}}</literal>,
2428 followed by a list of URL patterns, one per line, to which they apply.
2429 Together, the actions line and the following pattern lines make up a section
2430 of the actions file.
2434 Actions fall into three categories:
2441 Boolean, i.e the action can only be <quote>enabled</quote> or
2442 <quote>disabled</quote>. Syntax:
2446 +<replaceable class="function">name</replaceable> # enable action <replaceable class="parameter">name</replaceable>
2447 -<replaceable class="function">name</replaceable> # disable action <replaceable class="parameter">name</replaceable></screen>
2450 Example: <literal>+handle-as-image</literal>
2457 Parameterized, where some value is required in order to enable this type of action.
2462 +<replaceable class="function">name</replaceable>{<replaceable class="parameter">param</replaceable>} # enable action and set parameter to <replaceable class="parameter">param</replaceable>,
2463 # overwriting parameter from previous match if necessary
2464 -<replaceable class="function">name</replaceable> # disable action. The parameter can be omitted</screen>
2467 Note that if the URL matches multiple positive forms of a parameterized action,
2468 the last match wins, i.e. the params from earlier matches are simply ignored.
2471 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>
2477 Multi-value. These look exactly like parameterized actions,
2478 but they behave differently: If the action applies multiple times to the
2479 same URL, but with different parameters, <emphasis>all</emphasis> the parameters
2480 from <emphasis>all</emphasis> matches are remembered. This is used for actions
2481 that can be executed for the same request repeatedly, like adding multiple
2482 headers, or filtering through multiple filters. Syntax:
2486 +<replaceable class="function">name</replaceable>{<replaceable class="parameter">param</replaceable>} # enable action and add <replaceable class="parameter">param</replaceable> to the list of parameters
2487 -<replaceable class="function">name</replaceable>{<replaceable class="parameter">param</replaceable>} # remove the parameter <replaceable class="parameter">param</replaceable> from the list of parameters
2488 # If it was the last one left, disable the action.
2489 <replaceable class="parameter">-name</replaceable> # disable this action completely and remove all parameters from the list</screen>
2492 Examples: <literal>+add-header{X-Fun-Header: Some text}</literal> and
2493 <literal>+filter{html-annoyances}</literal>
2501 If nothing is specified in any actions file, no <quote>actions</quote> are
2502 taken. So in this case <application>Privoxy</application> would just be a
2503 normal, non-blocking, non-filtering proxy. You must specifically enable the
2504 privacy and blocking features you need (although the provided default actions
2505 files will give a good starting point).
2509 Later defined action sections always over-ride earlier ones of the same type.
2510 So exceptions to any rules you make, should come in the latter part of the file (or
2511 in a file that is processed later when using multiple actions files such
2512 as <filename>user.action</filename>). For multi-valued actions, the actions
2513 are applied in the order they are specified. Actions files are processed in
2514 the order they are defined in <filename>config</filename> (the default
2515 installation has three actions files). It also quite possible for any given
2516 URL to match more than one <quote>pattern</quote> (because of wildcards and
2517 regular expressions), and thus to trigger more than one set of actions! Last
2521 <!-- start actions listing -->
2523 The list of valid <application>Privoxy</application> actions are:
2527 <!-- ********************************************************** -->
2528 <!-- Please note the below defined actions use id's that are -->
2529 <!-- probably linked from other places, so please don't change. -->
2531 <!-- ********************************************************** -->
2534 <!-- ~~~~~ New section ~~~~~ -->
2536 <sect3 renderas="sect4" id="add-header">
2537 <title>add-header</title>
2541 <term>Typical use:</term>
2543 <para>Confuse log analysis, custom applications</para>
2548 <term>Effect:</term>
2551 Sends a user defined HTTP header to the web server.
2558 <!-- boolean, parameterized, Multi-value -->
2560 <para>Multi-value.</para>
2565 <term>Parameter:</term>
2568 Any string value is possible. Validity of the defined HTTP headers is not checked.
2569 It is recommended that you use the <quote><literal>X-</literal></quote> prefix
2579 This action may be specified multiple times, in order to define multiple
2580 headers. This is rarely needed for the typical user. If you don't know what
2581 <quote>HTTP headers</quote> are, you definitely don't need to worry about this
2585 Headers added by this action are not modified by other actions.
2591 <term>Example usage:</term>
2594 <screen>+add-header{X-User-Tracking: sucks}</screen>
2602 <!-- ~~~~~ New section ~~~~~ -->
2603 <sect3 renderas="sect4" id="block">
2604 <title>block</title>
2608 <term>Typical use:</term>
2610 <para>Block ads or other unwanted content</para>
2615 <term>Effect:</term>
2618 Requests for URLs to which this action applies are blocked, i.e. the
2619 requests are trapped by &my-app; and the requested URL is never retrieved,
2620 but is answered locally with a substitute page or image, as determined by
2622 linkend="handle-as-image">handle-as-image</link></literal>,
2624 linkend="set-image-blocker">set-image-blocker</link></literal>, and
2626 linkend="handle-as-empty-document">handle-as-empty-document</link></literal> actions.
2634 <!-- boolean, parameterized, Multi-value -->
2636 <para>Parameterized.</para>
2641 <term>Parameter:</term>
2643 <para>A block reason that should be given to the user.</para>
2651 <application>Privoxy</application> sends a special <quote>BLOCKED</quote> page
2652 for requests to blocked pages. This page contains the block reason given as
2653 parameter, a link to find out why the block action applies, and a click-through
2654 to the blocked content (the latter only if the force feature is available and
2658 A very important exception occurs if <emphasis>both</emphasis>
2659 <literal>block</literal> and <literal><link linkend="handle-as-image">handle-as-image</link></literal>,
2660 apply to the same request: it will then be replaced by an image. If
2661 <literal><link linkend="set-image-blocker">set-image-blocker</link></literal>
2662 (see below) also applies, the type of image will be determined by its parameter,
2663 if not, the standard checkerboard pattern is sent.
2666 It is important to understand this process, in order
2667 to understand how <application>Privoxy</application> deals with
2668 ads and other unwanted content. Blocking is a core feature, and one
2669 upon which various other features depend.
2672 The <literal><link linkend="filter">filter</link></literal>
2673 action can perform a very similar task, by <quote>blocking</quote>
2674 banner images and other content through rewriting the relevant URLs in the
2675 document's HTML source, so they don't get requested in the first place.
2676 Note that this is a totally different technique, and it's easy to confuse the two.
2682 <term>Example usage (section):</term>
2685 <screen>{+block{No nasty stuff for you.}}
2686 # Block and replace with "blocked" page
2687 .nasty-stuff.example.com
2689 {+block{Doubleclick banners.} +handle-as-image}
2690 # Block and replace with image
2694 {+block{Layered ads.} +handle-as-empty-document}
2695 # Block and then ignore
2696 adserver.example.net/.*\.js$</screen>
2706 <!-- ~~~~~ New section ~~~~~ -->
2707 <sect3 renderas="sect4" id="change-x-forwarded-for">
2708 <title>change-x-forwarded-for</title>
2712 <term>Typical use:</term>
2714 <para>Improve privacy by not forwarding the source of the request in the HTTP headers.</para>
2719 <term>Effect:</term>
2722 Deletes the <quote>X-Forwarded-For:</quote> HTTP header from the client request,
2730 <!-- Boolean, Parameterized, Multi-value -->
2732 <para>Parameterized.</para>
2737 <term>Parameter:</term>
2741 <para><quote>block</quote> to delete the header.</para>
2745 <quote>add</quote> to create the header (or append
2746 the client's IP address to an already existing one).
2757 It is safe and recommended to use <literal>block</literal>.
2760 Forwarding the source address of the request may make
2761 sense in some multi-user setups but is also a privacy risk.
2766 <term>Example usage:</term>
2769 <screen>+change-x-forwarded-for{block}</screen>
2776 <!-- ~~~~~ New section ~~~~~ -->
2777 <sect3 renderas="sect4" id="client-header-filter">
2778 <title>client-header-filter</title>
2782 <term>Typical use:</term>
2785 Rewrite or remove single client headers.
2791 <term>Effect:</term>
2794 All client headers to which this action applies are filtered on-the-fly through
2795 the specified regular expression based substitutions.
2802 <!-- boolean, parameterized, Multi-value -->
2804 <para>Multi-value.</para>
2809 <term>Parameter:</term>
2812 The name of a client-header filter, as defined in one of the
2813 <link linkend="filter-file">filter files</link>.
2822 Client-header filters are applied to each header on its own, not to
2823 all at once. This makes it easier to diagnose problems, but on the downside
2824 you can't write filters that only change header x if header y's value is z.
2825 You can do that by using tags though.
2828 Client-header filters are executed after the other header actions have finished
2829 and use their output as input.
2832 If the request URI gets changed, &my-app; will detect that and use the new
2833 one. This can be used to rewrite the request destination behind the client's
2834 back, for example to specify a Tor exit relay for certain requests.
2837 Please refer to the <link linkend="filter-file">filter file chapter</link>
2838 to learn which client-header filters are available by default, and how to
2846 <term>Example usage (section):</term>
2850 # Hide Tor exit notation in Host and Referer Headers
2851 {+client-header-filter{hide-tor-exit-notation}}
2862 <!-- ~~~~~ New section ~~~~~ -->
2863 <sect3 renderas="sect4" id="client-header-tagger">
2864 <title>client-header-tagger</title>
2868 <term>Typical use:</term>
2871 Block requests based on their headers.
2877 <term>Effect:</term>
2880 Client headers to which this action applies are filtered on-the-fly through
2881 the specified regular expression based substitutions, the result is used as
2889 <!-- boolean, parameterized, Multi-value -->
2891 <para>Multi-value.</para>
2896 <term>Parameter:</term>
2899 The name of a client-header tagger, as defined in one of the
2900 <link linkend="filter-file">filter files</link>.
2909 Client-header taggers are applied to each header on its own,
2910 and as the header isn't modified, each tagger <quote>sees</quote>
2914 Client-header taggers are the first actions that are executed
2915 and their tags can be used to control every other action.
2921 <term>Example usage (section):</term>
2925 # Tag every request with the User-Agent header
2926 {+client-header-tagger{user-agent}}
2929 # Tagging itself doesn't change the action
2930 # settings, sections with TAG patterns do:
2932 # If it's a download agent, use a different forwarding proxy,
2933 # show the real User-Agent and make sure resume works.
2934 {+forward-override{forward-socks5 10.0.0.2:2222 .} \
2935 -hide-if-modified-since \
2936 -overwrite-last-modified \
2941 TAG:^User-Agent: NetBSD-ftp/
2942 TAG:^User-Agent: Novell ZYPP Installer
2943 TAG:^User-Agent: RPM APT-HTTP/
2944 TAG:^User-Agent: fetch libfetch/
2945 TAG:^User-Agent: Ubuntu APT-HTTP/
2946 TAG:^User-Agent: MPlayer/
2951 # Tag all requests with the Range header set
2952 {+client-header-tagger{range-requests}}
2955 # Disable filtering for the tagged requests.
2957 # With filtering enabled Privoxy would remove the Range headers
2958 # to be able to filter the whole response. The downside is that
2959 # it prevents clients from resuming downloads or skipping over
2960 # parts of multimedia files.
2961 {-filter -deanimate-gifs}
2972 <!-- ~~~~~ New section ~~~~~ -->
2973 <sect3 renderas="sect4" id="content-type-overwrite">
2974 <title>content-type-overwrite</title>
2978 <term>Typical use:</term>
2980 <para>Stop useless download menus from popping up, or change the browser's rendering mode</para>
2985 <term>Effect:</term>
2988 Replaces the <quote>Content-Type:</quote> HTTP server header.
2995 <!-- Boolean, Parameterized, Multi-value -->
2997 <para>Parameterized.</para>
3002 <term>Parameter:</term>
3014 The <quote>Content-Type:</quote> HTTP server header is used by the
3015 browser to decide what to do with the document. The value of this
3016 header can cause the browser to open a download menu instead of
3017 displaying the document by itself, even if the document's format is
3018 supported by the browser.
3021 The declared content type can also affect which rendering mode
3022 the browser chooses. If XHTML is delivered as <quote>text/html</quote>,
3023 many browsers treat it as yet another broken HTML document.
3024 If it is send as <quote>application/xml</quote>, browsers with
3025 XHTML support will only display it, if the syntax is correct.
3028 If you see a web site that proudly uses XHTML buttons, but sets
3029 <quote>Content-Type: text/html</quote>, you can use &my-app;
3030 to overwrite it with <quote>application/xml</quote> and validate
3031 the web master's claim inside your XHTML-supporting browser.
3032 If the syntax is incorrect, the browser will complain loudly.
3035 You can also go the opposite direction: if your browser prints
3036 error messages instead of rendering a document falsely declared
3037 as XHTML, you can overwrite the content type with
3038 <quote>text/html</quote> and have it rendered as broken HTML document.
3041 By default <literal>content-type-overwrite</literal> only replaces
3042 <quote>Content-Type:</quote> headers that look like some kind of text.
3043 If you want to overwrite it unconditionally, you have to combine it with
3044 <literal><link linkend="force-text-mode">force-text-mode</link></literal>.
3045 This limitation exists for a reason, think twice before circumventing it.
3048 Most of the time it's easier to replace this action with a custom
3049 <literal><link linkend="server-header-filter">server-header filter</link></literal>.
3050 It allows you to activate it for every document of a certain site and it will still
3051 only replace the content types you aimed at.
3054 Of course you can apply <literal>content-type-overwrite</literal>
3055 to a whole site and then make URL based exceptions, but it's a lot
3056 more work to get the same precision.
3062 <term>Example usage (sections):</term>
3065 <screen># Check if www.example.net/ really uses valid XHTML
3066 { +content-type-overwrite{application/xml} }
3069 # but leave the content type unmodified if the URL looks like a style sheet
3070 {-content-type-overwrite}
3071 www.example.net/.*\.css$
3072 www.example.net/.*style
3081 <!-- ~~~~~ New section ~~~~~ -->
3082 <sect3 renderas="sect4" id="crunch-client-header">
3086 <title>crunch-client-header</title>
3090 <term>Typical use:</term>
3092 <para>Remove a client header <application>Privoxy</application> has no dedicated action for.</para>
3097 <term>Effect:</term>
3100 Deletes every header sent by the client that contains the string the user supplied as parameter.
3107 <!-- Boolean, Parameterized, Multi-value -->
3109 <para>Parameterized.</para>
3114 <term>Parameter:</term>
3126 This action allows you to block client headers for which no dedicated
3127 <application>Privoxy</application> action exists.
3128 <application>Privoxy</application> will remove every client header that
3129 contains the string you supplied as parameter.
3132 Regular expressions are <emphasis>not supported</emphasis> and you can't
3133 use this action to block different headers in the same request, unless
3134 they contain the same string.
3137 <literal>crunch-client-header</literal> is only meant for quick tests.
3138 If you have to block several different headers, or only want to modify
3139 parts of them, you should use a
3140 <literal><link linkend="client-header-filter">client-header filter</link></literal>.
3144 Don't block any header without understanding the consequences.
3151 <term>Example usage (section):</term>
3154 <screen># Block the non-existent "Privacy-Violation:" client header
3155 { +crunch-client-header{Privacy-Violation:} }
3165 <!-- ~~~~~ New section ~~~~~ -->
3166 <sect3 renderas="sect4" id="crunch-if-none-match">
3167 <title>crunch-if-none-match</title>
3173 <term>Typical use:</term>
3175 <para>Prevent yet another way to track the user's steps between sessions.</para>
3180 <term>Effect:</term>
3183 Deletes the <quote>If-None-Match:</quote> HTTP client header.
3190 <!-- Boolean, Parameterized, Multi-value -->
3192 <para>Boolean.</para>
3197 <term>Parameter:</term>
3209 Removing the <quote>If-None-Match:</quote> HTTP client header
3210 is useful for filter testing, where you want to force a real
3211 reload instead of getting status code <quote>304</quote> which
3212 would cause the browser to use a cached copy of the page.
3215 It is also useful to make sure the header isn't used as a cookie
3216 replacement (unlikely but possible).
3219 Blocking the <quote>If-None-Match:</quote> header shouldn't cause any
3220 caching problems, as long as the <quote>If-Modified-Since:</quote> header
3221 isn't blocked or missing as well.
3224 It is recommended to use this action together with
3225 <literal><link linkend="hide-if-modified-since">hide-if-modified-since</link></literal>
3227 <literal><link linkend="overwrite-last-modified">overwrite-last-modified</link></literal>.
3233 <term>Example usage (section):</term>
3236 <screen># Let the browser revalidate cached documents but don't
3237 # allow the server to use the revalidation headers for user tracking.
3238 {+hide-if-modified-since{-60} \
3239 +overwrite-last-modified{randomize} \
3240 +crunch-if-none-match}
3249 <!-- ~~~~~ New section ~~~~~ -->
3250 <sect3 renderas="sect4" id="crunch-incoming-cookies">
3251 <title>crunch-incoming-cookies</title>
3255 <term>Typical use:</term>
3258 Prevent the web server from setting HTTP cookies on your system
3264 <term>Effect:</term>
3267 Deletes any <quote>Set-Cookie:</quote> HTTP headers from server replies.
3274 <!-- Boolean, Parameterized, Multi-value -->
3276 <para>Boolean.</para>
3281 <term>Parameter:</term>
3293 This action is only concerned with <emphasis>incoming</emphasis> HTTP cookies. For
3294 <emphasis>outgoing</emphasis> HTTP cookies, use
3295 <literal><link linkend="crunch-outgoing-cookies">crunch-outgoing-cookies</link></literal>.
3296 Use <emphasis>both</emphasis> to disable HTTP cookies completely.
3299 It makes <emphasis>no sense at all</emphasis> to use this action in conjunction
3300 with the <literal><link linkend="session-cookies-only">session-cookies-only</link></literal> action,
3301 since it would prevent the session cookies from being set. See also
3302 <literal><link linkend="filter-content-cookies">filter-content-cookies</link></literal>.
3308 <term>Example usage:</term>
3311 <screen>+crunch-incoming-cookies</screen>
3319 <!-- ~~~~~ New section ~~~~~ -->
3320 <sect3 renderas="sect4" id="crunch-server-header">
3321 <title>crunch-server-header</title>
3327 <term>Typical use:</term>
3329 <para>Remove a server header <application>Privoxy</application> has no dedicated action for.</para>
3334 <term>Effect:</term>
3337 Deletes every header sent by the server that contains the string the user supplied as parameter.
3344 <!-- Boolean, Parameterized, Multi-value -->
3346 <para>Parameterized.</para>
3351 <term>Parameter:</term>
3363 This action allows you to block server headers for which no dedicated
3364 <application>Privoxy</application> action exists. <application>Privoxy</application>
3365 will remove every server header that contains the string you supplied as parameter.
3368 Regular expressions are <emphasis>not supported</emphasis> and you can't
3369 use this action to block different headers in the same request, unless
3370 they contain the same string.
3373 <literal>crunch-server-header</literal> is only meant for quick tests.
3374 If you have to block several different headers, or only want to modify
3375 parts of them, you should use a custom
3376 <literal><link linkend="server-header-filter">server-header filter</link></literal>.
3380 Don't block any header without understanding the consequences.
3387 <term>Example usage (section):</term>
3390 <screen># Crunch server headers that try to prevent caching
3391 { +crunch-server-header{no-cache} }
3400 <!-- ~~~~~ New section ~~~~~ -->
3401 <sect3 renderas="sect4" id="crunch-outgoing-cookies">
3402 <title>crunch-outgoing-cookies</title>
3406 <term>Typical use:</term>
3409 Prevent the web server from reading any HTTP cookies from your system
3415 <term>Effect:</term>
3418 Deletes any <quote>Cookie:</quote> HTTP headers from client requests.
3425 <!-- Boolean, Parameterized, Multi-value -->
3427 <para>Boolean.</para>
3432 <term>Parameter:</term>
3444 This action is only concerned with <emphasis>outgoing</emphasis> HTTP cookies. For
3445 <emphasis>incoming</emphasis> HTTP cookies, use
3446 <literal><link linkend="crunch-incoming-cookies">crunch-incoming-cookies</link></literal>.
3447 Use <emphasis>both</emphasis> to disable HTTP cookies completely.
3450 It makes <emphasis>no sense at all</emphasis> to use this action in conjunction
3451 with the <literal><link linkend="session-cookies-only">session-cookies-only</link></literal> action,
3452 since it would prevent the session cookies from being read.
3458 <term>Example usage:</term>
3461 <screen>+crunch-outgoing-cookies</screen>
3470 <!-- ~~~~~ New section ~~~~~ -->
3471 <sect3 renderas="sect4" id="deanimate-gifs">
3472 <title>deanimate-gifs</title>
3476 <term>Typical use:</term>
3478 <para>Stop those annoying, distracting animated GIF images.</para>
3483 <term>Effect:</term>
3486 De-animate GIF animations, i.e. reduce them to their first or last image.
3493 <!-- boolean, parameterized, Multi-value -->
3495 <para>Parameterized.</para>
3500 <term>Parameter:</term>
3503 <quote>last</quote> or <quote>first</quote>
3512 This will also shrink the images considerably (in bytes, not pixels!). If
3513 the option <quote>first</quote> is given, the first frame of the animation
3514 is used as the replacement. If <quote>last</quote> is given, the last
3515 frame of the animation is used instead, which probably makes more sense for
3516 most banner animations, but also has the risk of not showing the entire
3517 last frame (if it is only a delta to an earlier frame).
3520 You can safely use this action with patterns that will also match non-GIF
3521 objects, because no attempt will be made at anything that doesn't look like
3528 <term>Example usage:</term>
3531 <screen>+deanimate-gifs{last}</screen>
3538 <!-- ~~~~~ New section ~~~~~ -->
3539 <sect3 renderas="sect4" id="downgrade-http-version">
3540 <title>downgrade-http-version</title>
3544 <term>Typical use:</term>
3546 <para>Work around (very rare) problems with HTTP/1.1</para>
3551 <term>Effect:</term>
3554 Downgrades HTTP/1.1 client requests and server replies to HTTP/1.0.
3561 <!-- boolean, parameterized, Multi-value -->
3563 <para>Boolean.</para>
3568 <term>Parameter:</term>
3580 This is a left-over from the time when <application>Privoxy</application>
3581 didn't support important HTTP/1.1 features well. It is left here for the
3582 unlikely case that you experience HTTP/1.1-related problems with some server
3586 Note that enabling this action is only a workaround. It should not
3587 be enabled for sites that work without it. While it shouldn't break
3588 any pages, it has an (usually negative) performance impact.
3591 If you come across a site where enabling this action helps, please report it,
3592 so the cause of the problem can be analyzed. If the problem turns out to be
3593 caused by a bug in <application>Privoxy</application> it should be
3594 fixed so the following release works without the work around.
3600 <term>Example usage (section):</term>
3603 <screen>{+downgrade-http-version}
3604 problem-host.example.com</screen>
3612 <!-- ~~~~~ New section ~~~~~ -->
3613 <sect3 renderas="sect4" id="external-filter">
3614 <title>external-filter</title>
3618 <term>Typical use:</term>
3620 <para>Modify content using a programming language of your choice.</para>
3625 <term>Effect:</term>
3628 All instances of text-based type, most notably HTML and JavaScript, to which
3629 this action applies, can be filtered on-the-fly through the specified external
3631 By default plain text documents are exempted from filtering, because web
3632 servers often use the <literal>text/plain</literal> MIME type for all files
3633 whose type they don't know.)
3640 <!-- boolean, parameterized, Multi-value -->
3642 <para>Multi-value.</para>
3647 <term>Parameter:</term>
3650 The name of an external content filter, as defined in the
3651 <link linkend="filter-file">filter file</link>.
3652 External filters can be defined in one or more files as defined by the
3653 <literal><link linkend="filterfile">filterfile</link></literal>
3654 option in the <link linkend="config">config file</link>.
3657 When used in its negative form,
3658 and without parameters, <emphasis>all</emphasis> filtering with external
3659 filters is completely disabled.
3668 External filters are scripts or programs that can modify the content in
3669 case common <literal><link linkend="filter">filters</link></literal>
3670 aren't powerful enough. With the exception that this action doesn't
3671 use pcrs-based filters, the notes in the
3672 <literal><link linkend="filter">filter</link></literal> section apply.
3676 Currently external filters are executed with &my-app;'s privileges.
3677 Only use external filters you understand and trust.
3681 This feature is experimental, the <literal><link
3682 linkend="external-filter-syntax">syntax</link></literal>
3683 may change in the future.
3690 <term>Example usage:</term>
3693 <screen>+external-filter{fancy-filter}</screen>
3700 <!-- ~~~~~ New section ~~~~~ -->
3701 <sect3 renderas="sect4" id="fast-redirects">
3702 <title>fast-redirects</title>
3706 <term>Typical use:</term>
3708 <para>Fool some click-tracking scripts and speed up indirect links.</para>
3713 <term>Effect:</term>
3716 Detects redirection URLs and redirects the browser without contacting
3717 the redirection server first.
3724 <!-- boolean, parameterized, Multi-value -->
3726 <para>Parameterized.</para>
3731 <term>Parameter:</term>
3736 <quote>simple-check</quote> to just search for the string <quote>http://</quote>
3737 to detect redirection URLs.
3742 <quote>check-decoded-url</quote> to decode URLs (if necessary) before searching
3743 for redirection URLs.
3754 Many sites, like yahoo.com, don't just link to other sites. Instead, they
3755 will link to some script on their own servers, giving the destination as a
3756 parameter, which will then redirect you to the final target. URLs
3757 resulting from this scheme typically look like:
3758 <quote>http://www.example.org/click-tracker.cgi?target=http%3a//www.example.net/</quote>.
3761 Sometimes, there are even multiple consecutive redirects encoded in the
3762 URL. These redirections via scripts make your web browsing more traceable,
3763 since the server from which you follow such a link can see where you go
3764 to. Apart from that, valuable bandwidth and time is wasted, while your
3765 browser asks the server for one redirect after the other. Plus, it feeds
3769 This feature is currently not very smart and is scheduled for improvement.
3770 If it is enabled by default, you will have to create some exceptions to
3771 this action. It can lead to failures in several ways:
3774 Not every URLs with other URLs as parameters is evil.
3775 Some sites offer a real service that requires this information to work.
3776 For example a validation service needs to know, which document to validate.
3777 <literal>fast-redirects</literal> assumes that every URL parameter that
3778 looks like another URL is a redirection target, and will always redirect to
3779 the last one. Most of the time the assumption is correct, but if it isn't,
3780 the user gets redirected anyway.
3783 Another failure occurs if the URL contains other parameters after the URL parameter.
3785 <quote>http://www.example.org/?redirect=http%3a//www.example.net/&foo=bar</quote>.
3786 contains the redirection URL <quote>http://www.example.net/</quote>,
3787 followed by another parameter. <literal>fast-redirects</literal> doesn't know that
3788 and will cause a redirect to <quote>http://www.example.net/&foo=bar</quote>.
3789 Depending on the target server configuration, the parameter will be silently ignored
3790 or lead to a <quote>page not found</quote> error. You can prevent this problem by
3791 first using the <literal><link linkend="redirect">redirect</link></literal> action
3792 to remove the last part of the URL, but it requires a little effort.
3795 To detect a redirection URL, <literal>fast-redirects</literal> only
3796 looks for the string <quote>http://</quote>, either in plain text
3797 (invalid but often used) or encoded as <quote>http%3a//</quote>.
3798 Some sites use their own URL encoding scheme, encrypt the address
3799 of the target server or replace it with a database id. In theses cases
3800 <literal>fast-redirects</literal> is fooled and the request reaches the
3801 redirection server where it probably gets logged.
3807 <term>Example usage:</term>
3811 { +fast-redirects{simple-check} }
3814 { +fast-redirects{check-decoded-url} }
3815 another.example.com/testing</screen>
3824 <!-- ~~~~~ New section ~~~~~ -->
3825 <sect3 renderas="sect4" id="filter">
3826 <title>filter</title>
3830 <term>Typical use:</term>
3832 <para>Get rid of HTML and JavaScript annoyances, banner advertisements (by size),
3833 do fun text replacements, add personalized effects, etc.</para>
3838 <term>Effect:</term>
3841 All instances of text-based type, most notably HTML and JavaScript, to which
3842 this action applies, can be filtered on-the-fly through the specified regular
3843 expression based substitutions. (Note: as of version 3.0.3 plain text documents
3844 are exempted from filtering, because web servers often use the
3845 <literal>text/plain</literal> MIME type for all files whose type they don't know.)
3852 <!-- boolean, parameterized, Multi-value -->
3854 <para>Multi-value.</para>
3859 <term>Parameter:</term>
3862 The name of a content filter, as defined in the <link linkend="filter-file">filter file</link>.
3863 Filters can be defined in one or more files as defined by the
3864 <literal><link linkend="filterfile">filterfile</link></literal>
3865 option in the <link linkend="config">config file</link>.
3866 <filename>default.filter</filename> is the collection of filters
3867 supplied by the developers. Locally defined filters should go
3868 in their own file, such as <filename>user.filter</filename>.
3871 When used in its negative form,
3872 and without parameters, <emphasis>all</emphasis> filtering is completely disabled.
3881 For your convenience, there are a number of pre-defined filters available
3882 in the distribution filter file that you can use. See the examples below for
3886 Filtering requires buffering the page content, which may appear to
3887 slow down page rendering since nothing is displayed until all content has
3888 passed the filters. (The total time until the page is completely rendered
3889 doesn't change much, but it may be perceived as slower since the page is
3890 not incrementally displayed.)
3891 This effect will be more noticeable on slower connections.
3894 <quote>Rolling your own</quote>
3895 filters requires a knowledge of
3896 <ulink url="http://en.wikipedia.org/wiki/Regular_expressions"><quote>Regular
3897 Expressions</quote></ulink> and
3898 <ulink url="http://en.wikipedia.org/wiki/Html"><quote>HTML</quote></ulink>.
3899 This is very powerful feature, and potentially very intrusive.
3900 Filters should be used with caution, and where an equivalent
3901 <quote>action</quote> is not available.
3904 The amount of data that can be filtered is limited to the
3905 <literal><link linkend="buffer-limit">buffer-limit</link></literal>
3906 option in the main <link linkend="config">config file</link>. The
3907 default is 4096 KB (4 Megs). Once this limit is exceeded, the buffered
3908 data, and all pending data, is passed through unfiltered.
3911 Inappropriate MIME types, such as zipped files, are not filtered at all.
3912 (Again, only text-based types except plain text). Encrypted SSL data
3913 (from HTTPS servers) cannot be filtered either, since this would violate
3914 the integrity of the secure transaction. In some situations it might
3915 be necessary to protect certain text, like source code, from filtering
3916 by defining appropriate <literal>-filter</literal> exceptions.
3919 Compressed content can't be filtered either, but if &my-app;
3920 is compiled with zlib support and a supported compression algorithm
3921 is used (gzip or deflate), &my-app; can first decompress the content
3925 If you use a &my-app; version without zlib support, but want filtering to work on
3926 as much documents as possible, even those that would normally be sent compressed,
3927 you must use the <literal><link linkend="prevent-compression">prevent-compression</link></literal>
3928 action in conjunction with <literal>filter</literal>.
3931 Content filtering can achieve some of the same effects as the
3932 <literal><link linkend="block">block</link></literal>
3933 action, i.e. it can be used to block ads and banners. But the mechanism
3934 works quite differently. One effective use, is to block ad banners
3935 based on their size (see below), since many of these seem to be somewhat
3939 <link linkend="contact">Feedback</link> with suggestions for new or
3940 improved filters is particularly welcome!
3943 The below list has only the names and a one-line description of each
3944 predefined filter. There are <link linkend="predefined-filters">more
3945 verbose explanations</link> of what these filters do in the <link
3946 linkend="filter-file">filter file chapter</link>.
3952 <term>Example usage (with filters from the distribution <filename>default.filter</filename> file).
3953 See <link linkend="PREDEFINED-FILTERS">the Predefined Filters section</link> for
3954 more explanation on each:</term>
3957 <anchor id="filter-js-annoyances">
3958 <screen>+filter{js-annoyances} # Get rid of particularly annoying JavaScript abuse.</screen>
3961 <anchor id="filter-js-events">
3962 <screen>+filter{js-events} # Kill JavaScript event bindings and timers (Radically destructive! Only for extra nasty sites).</screen>
3965 <anchor id="filter-html-annoyances">
3966 <screen>+filter{html-annoyances} # Get rid of particularly annoying HTML abuse.</screen>
3969 <anchor id="filter-content-cookies">
3970 <screen>+filter{content-cookies} # Kill cookies that come in the HTML or JS content.</screen>
3973 <anchor id="filter-refresh-tags">
3974 <screen>+filter{refresh-tags} # Kill automatic refresh tags if refresh time is larger than 9 seconds.</screen>
3977 <anchor id="filter-unsolicited-popups">
3978 <screen>+filter{unsolicited-popups} # Disable only unsolicited pop-up windows.</screen>
3981 <anchor id="filter-all-popups">
3982 <screen>+filter{all-popups} # Kill all popups in JavaScript and HTML.</screen>
3985 <anchor id="filter-img-reorder">
3986 <screen>+filter{img-reorder} # Reorder attributes in <img> tags to make the banners-by-* filters more effective.</screen>
3989 <anchor id="filter-banners-by-size">
3990 <screen>+filter{banners-by-size} # Kill banners by size.</screen>
3993 <anchor id="filter-banners-by-link">
3994 <screen>+filter{banners-by-link} # Kill banners by their links to known clicktrackers.</screen>
3997 <anchor id="filter-webbugs">
3998 <screen>+filter{webbugs} # Squish WebBugs (1x1 invisible GIFs used for user tracking).</screen>
4001 <anchor id="filter-tiny-textforms">
4002 <screen>+filter{tiny-textforms} # Extend those tiny textareas up to 40x80 and kill the hard wrap.</screen>
4005 <anchor id="filter-jumping-windows">
4006 <screen>+filter{jumping-windows} # Prevent windows from resizing and moving themselves.</screen>
4009 <anchor id="filter-frameset-borders">
4010 <screen>+filter{frameset-borders} # Give frames a border and make them resizable.</screen>
4013 <anchor id="filter-iframes">
4014 <screen>+filter{iframes} # Removes all detected iframes. Should only be enabled for individual sites.</screen>
4017 <anchor id="filter-demoronizer">
4018 <screen>+filter{demoronizer} # Fix MS's non-standard use of standard charsets.</screen>
4021 <anchor id="filter-shockwave-flash">
4022 <screen>+filter{shockwave-flash} # Kill embedded Shockwave Flash objects.</screen>
4025 <anchor id="filter-quicktime-kioskmode">
4026 <screen>+filter{quicktime-kioskmode} # Make Quicktime movies saveable.</screen>
4029 <anchor id="filter-fun">
4030 <screen>+filter{fun} # Text replacements for subversive browsing fun!</screen>
4033 <anchor id="filter-crude-parental">
4034 <screen>+filter{crude-parental} # Crude parental filtering. Note that this filter doesn't work reliably.</screen>
4037 <anchor id="filter-ie-exploits">
4038 <screen>+filter{ie-exploits} # Disable some known Internet Explorer bug exploits.</screen>
4041 <anchor id="filter-site-specifics">
4042 <screen>+filter{site-specifics} # Cure for site-specific problems. Don't apply generally!</screen>
4045 <anchor id="filter-no-ping">
4046 <screen>+filter{no-ping} # Removes non-standard ping attributes in <a> and <area> tags.</screen>
4049 <anchor id="filter-google">
4050 <screen>+filter{google} # CSS-based block for Google text ads. Also removes a width limitation and the toolbar advertisement.</screen>
4053 <anchor id="filter-yahoo">
4054 <screen>+filter{yahoo} # CSS-based block for Yahoo text ads. Also removes a width limitation.</screen>
4057 <anchor id="filter-msn">
4058 <screen>+filter{msn} # CSS-based block for MSN text ads. Also removes tracking URLs and a width limitation.</screen>
4061 <anchor id="filter-blogspot">
4062 <screen>+filter{blogspot} # Cleans up some Blogspot blogs. Read the fine print before using this.</screen>
4070 <!-- ~~~~~ New section ~~~~~ -->
4071 <sect3 renderas="sect4" id="force-text-mode">
4072 <title>force-text-mode</title>
4078 <term>Typical use:</term>
4080 <para>Force <application>Privoxy</application> to treat a document as if it was in some kind of <emphasis>text</emphasis> format. </para>
4085 <term>Effect:</term>
4088 Declares a document as text, even if the <quote>Content-Type:</quote> isn't detected as such.
4095 <!-- Boolean, Parameterized, Multi-value -->
4097 <para>Boolean.</para>
4102 <term>Parameter:</term>
4114 As explained <literal><link linkend="filter">above</link></literal>,
4115 <application>Privoxy</application> tries to only filter files that are
4116 in some kind of text format. The same restrictions apply to
4117 <literal><link linkend="content-type-overwrite">content-type-overwrite</link></literal>.
4118 <literal>force-text-mode</literal> declares a document as text,
4119 without looking at the <quote>Content-Type:</quote> first.
4123 Think twice before activating this action. Filtering binary data
4124 with regular expressions can cause file damage.
4131 <term>Example usage:</term>
4144 <!-- ~~~~~ New section ~~~~~ -->
4145 <sect3 renderas="sect4" id="forward-override">
4146 <title>forward-override</title>
4152 <term>Typical use:</term>
4154 <para>Change the forwarding settings based on User-Agent or request origin</para>
4159 <term>Effect:</term>
4162 Overrules the forward directives in the configuration file.
4169 <!-- Boolean, Parameterized, Multi-value -->
4171 <para>Parameterized.</para>
4176 <term>Parameter:</term>
4180 <para><quote>forward .</quote> to use a direct connection without any additional proxies.</para>
4184 <quote>forward 127.0.0.1:8123</quote> to use the HTTP proxy listening at 127.0.0.1 port 8123.
4189 <quote>forward-socks4a 127.0.0.1:9050 .</quote> to use the socks4a proxy listening at
4190 127.0.0.1 port 9050. Replace <quote>forward-socks4a</quote> with <quote>forward-socks4</quote>
4191 to use a socks4 connection (with local DNS resolution) instead, use <quote>forward-socks5</quote>
4192 for socks5 connections (with remote DNS resolution).
4197 <quote>forward-socks4a 127.0.0.1:9050 proxy.example.org:8000</quote> to use the socks4a proxy
4198 listening at 127.0.0.1 port 9050 to reach the HTTP proxy listening at proxy.example.org port 8000.
4199 Replace <quote>forward-socks4a</quote> with <quote>forward-socks4</quote> to use a socks4 connection
4200 (with local DNS resolution) instead, use <quote>forward-socks5</quote>
4201 for socks5 connections (with remote DNS resolution).
4206 <quote>forward-webserver 127.0.0.1:80</quote> to use the HTTP
4207 server listening at 127.0.0.1 port 80 without adjusting the
4211 This makes it more convenient to use Privoxy to make
4212 existing websites available as onion services as well.
4215 Many websites serve content with hardcoded URLs and
4216 can't be easily adjusted to change the domain based
4217 on the one used by the client.
4220 Putting Privoxy between Tor and the webserver (or an stunnel
4221 that forwards to the webserver) allows to rewrite headers and
4222 content to make client and server happy at the same time.
4225 Using Privoxy for webservers that are only reachable through
4226 onion addresses and whose location is supposed to be secret
4227 is not recommended and should not be necessary anyway.
4238 This action takes parameters similar to the
4239 <link linkend="forwarding">forward</link> directives in the configuration
4240 file, but without the URL pattern. It can be used as replacement, but normally it's only
4241 used in cases where matching based on the request URL isn't sufficient.
4245 Please read the description for the <link linkend="forwarding">forward</link> directives before
4246 using this action. Forwarding to the wrong people will reduce your privacy and increase the
4247 chances of man-in-the-middle attacks.
4250 If the ports are missing or invalid, default values will be used. This might change
4251 in the future and you shouldn't rely on it. Otherwise incorrect syntax causes Privoxy
4252 to exit. Due to design limitations, invalid parameter syntax isn't detected until the
4253 action is used the first time.
4256 Use the <ulink url="http://config.privoxy.org/show-url-info">show-url-info CGI page</ulink>
4257 to verify that your forward settings do what you thought the do.
4264 <term>Example usage:</term>
4268 # Use an ssh tunnel for requests previously tagged as
4269 # <quote>User-Agent: fetch libfetch/2.0</quote> and make sure
4270 # resuming downloads continues to work.
4272 # This way you can continue to use Tor for your normal browsing,
4273 # without overloading the Tor network with your FreeBSD ports updates
4274 # or downloads of bigger files like ISOs.
4276 # Note that HTTP headers are easy to fake and therefore their
4277 # values are as (un)trustworthy as your clients and users.
4278 {+forward-override{forward-socks5 10.0.0.2:2222 .} \
4279 -hide-if-modified-since \
4280 -overwrite-last-modified \
4282 TAG:^User-Agent: fetch libfetch/2\.0$
4291 <!-- ~~~~~ New section ~~~~~ -->
4292 <sect3 renderas="sect4" id="handle-as-empty-document">
4293 <title>handle-as-empty-document</title>
4299 <term>Typical use:</term>
4301 <para>Mark URLs that should be replaced by empty documents <emphasis>if they get blocked</emphasis></para>
4306 <term>Effect:</term>
4309 This action alone doesn't do anything noticeable. It just marks URLs.
4310 If the <literal><link linkend="block">block</link></literal> action <emphasis>also applies</emphasis>,
4311 the presence or absence of this mark decides whether an HTML <quote>BLOCKED</quote>
4312 page, or an empty document will be sent to the client as a substitute for the blocked content.
4313 The <emphasis>empty</emphasis> document isn't literally empty, but actually contains a single space.
4320 <!-- Boolean, Parameterized, Multi-value -->
4322 <para>Boolean.</para>
4327 <term>Parameter:</term>
4339 Some browsers complain about syntax errors if JavaScript documents
4340 are blocked with <application>Privoxy's</application>
4341 default HTML page; this option can be used to silence them.
4342 And of course this action can also be used to eliminate the &my-app;
4343 BLOCKED message in frames.
4346 The content type for the empty document can be specified with
4347 <literal><link linkend="content-type-overwrite">content-type-overwrite{}</link></literal>,
4348 but usually this isn't necessary.
4354 <term>Example usage:</term>
4357 <screen># Block all documents on example.org that end with ".js",
4358 # but send an empty document instead of the usual HTML message.
4359 {+block{Blocked JavaScript} +handle-as-empty-document}
4369 <!-- ~~~~~ New section ~~~~~ -->
4370 <sect3 renderas="sect4" id="handle-as-image">
4371 <title>handle-as-image</title>
4375 <term>Typical use:</term>
4377 <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>
4382 <term>Effect:</term>
4385 This action alone doesn't do anything noticeable. It just marks URLs as images.
4386 If the <literal><link linkend="block">block</link></literal> action <emphasis>also applies</emphasis>,
4387 the presence or absence of this mark decides whether an HTML <quote>blocked</quote>
4388 page, or a replacement image (as determined by the <literal><link
4389 linkend="set-image-blocker">set-image-blocker</link></literal> action) will be sent to the
4390 client as a substitute for the blocked content.
4397 <!-- Boolean, Parameterized, Multi-value -->
4399 <para>Boolean.</para>
4404 <term>Parameter:</term>
4416 The below generic example section is actually part of <filename>default.action</filename>.
4417 It marks all URLs with well-known image file name extensions as images and should
4421 Users will probably only want to use the handle-as-image action in conjunction with
4422 <literal><link linkend="block">block</link></literal>, to block sources of banners, whose URLs don't
4423 reflect the file type, like in the second example section.
4426 Note that you cannot treat HTML pages as images in most cases. For instance, (in-line) ad
4427 frames require an HTML page to be sent, or they won't display properly.
4428 Forcing <literal>handle-as-image</literal> in this situation will not replace the
4429 ad frame with an image, but lead to error messages.
4435 <term>Example usage (sections):</term>
4438 <screen># Generic image extensions:
4441 /.*\.(gif|jpg|jpeg|png|bmp|ico)$
4443 # These don't look like images, but they're banners and should be
4444 # blocked as images:
4446 {+block{Nasty banners.} +handle-as-image}
4447 nasty-banner-server.example.com/junk.cgi\?output=trash
4456 <!-- ~~~~~ New section ~~~~~ -->
4457 <sect3 renderas="sect4" id="hide-accept-language">
4458 <title>hide-accept-language</title>
4464 <term>Typical use:</term>
4466 <para>Pretend to use different language settings.</para>
4471 <term>Effect:</term>
4474 Deletes or replaces the <quote>Accept-Language:</quote> HTTP header in client requests.
4481 <!-- Boolean, Parameterized, Multi-value -->
4483 <para>Parameterized.</para>
4488 <term>Parameter:</term>
4491 Keyword: <quote>block</quote>, or any user defined value.
4500 Faking the browser's language settings can be useful to make a
4501 foreign User-Agent set with
4502 <literal><link linkend="hide-user-agent">hide-user-agent</link></literal>
4506 However some sites with content in different languages check the
4507 <quote>Accept-Language:</quote> to decide which one to take by default.
4508 Sometimes it isn't possible to later switch to another language without
4509 changing the <quote>Accept-Language:</quote> header first.
4512 Therefore it's a good idea to either only change the
4513 <quote>Accept-Language:</quote> header to languages you understand,
4514 or to languages that aren't wide spread.
4517 Before setting the <quote>Accept-Language:</quote> header
4518 to a rare language, you should consider that it helps to
4519 make your requests unique and thus easier to trace.
4520 If you don't plan to change this header frequently,
4521 you should stick to a common language.
4527 <term>Example usage (section):</term>
4530 <screen># Pretend to use Canadian language settings.
4531 {+hide-accept-language{en-ca} \
4532 +hide-user-agent{Mozilla/5.0 (X11; U; OpenBSD i386; en-CA; rv:1.8.0.4) Gecko/20060628 Firefox/1.5.0.4} \
4542 <!-- ~~~~~ New section ~~~~~ -->
4543 <sect3 renderas="sect4" id="hide-content-disposition">
4544 <title>hide-content-disposition</title>
4550 <term>Typical use:</term>
4552 <para>Prevent download menus for content you prefer to view inside the browser.</para>
4557 <term>Effect:</term>
4560 Deletes or replaces the <quote>Content-Disposition:</quote> HTTP header set by some servers.
4567 <!-- Boolean, Parameterized, Multi-value -->
4569 <para>Parameterized.</para>
4574 <term>Parameter:</term>
4577 Keyword: <quote>block</quote>, or any user defined value.
4586 Some servers set the <quote>Content-Disposition:</quote> HTTP header for
4587 documents they assume you want to save locally before viewing them.
4588 The <quote>Content-Disposition:</quote> header contains the file name
4589 the browser is supposed to use by default.
4592 In most browsers that understand this header, it makes it impossible to
4593 <emphasis>just view</emphasis> the document, without downloading it first,
4594 even if it's just a simple text file or an image.
4597 Removing the <quote>Content-Disposition:</quote> header helps
4598 to prevent this annoyance, but some browsers additionally check the
4599 <quote>Content-Type:</quote> header, before they decide if they can
4600 display a document without saving it first. In these cases, you have
4601 to change this header as well, before the browser stops displaying
4605 It is also possible to change the server's file name suggestion
4606 to another one, but in most cases it isn't worth the time to set
4610 This action will probably be removed in the future,
4611 use server-header filters instead.
4617 <term>Example usage:</term>
4620 <screen># Disarm the download link in Sourceforge's patch tracker
4622 +content-type-overwrite{text/plain}\
4623 +hide-content-disposition{block} }
4624 .sourceforge.net/tracker/download\.php</screen>
4632 <!-- ~~~~~ New section ~~~~~ -->
4633 <sect3 renderas="sect4" id="hide-if-modified-since">
4634 <title>hide-if-modified-since</title>
4640 <term>Typical use:</term>
4642 <para>Prevent yet another way to track the user's steps between sessions.</para>
4647 <term>Effect:</term>
4650 Deletes the <quote>If-Modified-Since:</quote> HTTP client header or modifies its value.
4657 <!-- Boolean, Parameterized, Multi-value -->
4659 <para>Parameterized.</para>
4664 <term>Parameter:</term>
4667 Keyword: <quote>block</quote>, or a user defined value that specifies a range of hours.
4676 Removing this header is useful for filter testing, where you want to force a real
4677 reload instead of getting status code <quote>304</quote>, which would cause the
4678 browser to use a cached copy of the page.
4681 Instead of removing the header, <literal>hide-if-modified-since</literal> can
4682 also add or subtract a random amount of time to/from the header's value.
4683 You specify a range of minutes where the random factor should be chosen from and
4684 <application>Privoxy</application> does the rest. A negative value means
4685 subtracting, a positive value adding.
4688 Randomizing the value of the <quote>If-Modified-Since:</quote> makes
4689 it less likely that the server can use the time as a cookie replacement,
4690 but you will run into caching problems if the random range is too high.
4693 It is a good idea to only use a small negative value and let
4694 <literal><link linkend="overwrite-last-modified">overwrite-last-modified</link></literal>
4695 handle the greater changes.
4698 It is also recommended to use this action together with
4699 <literal><link linkend="crunch-if-none-match">crunch-if-none-match</link></literal>,
4700 otherwise it's more or less pointless.
4706 <term>Example usage (section):</term>
4709 <screen># Let the browser revalidate but make tracking based on the time less likely.
4710 {+hide-if-modified-since{-60} \
4711 +overwrite-last-modified{randomize} \
4712 +crunch-if-none-match}
4721 <!-- ~~~~~ New section ~~~~~ -->
4722 <sect3 renderas="sect4" id="hide-from-header">
4723 <title>hide-from-header</title>
4727 <term>Typical use:</term>
4729 <para>Keep your (old and ill) browser from telling web servers your email address</para>
4734 <term>Effect:</term>
4737 Deletes any existing <quote>From:</quote> HTTP header, or replaces it with the
4745 <!-- Boolean, Parameterized, Multi-value -->
4747 <para>Parameterized.</para>
4752 <term>Parameter:</term>
4755 Keyword: <quote>block</quote>, or any user defined value.
4764 The keyword <quote>block</quote> will completely remove the header
4765 (not to be confused with the <literal><link linkend="block">block</link></literal>
4769 Alternately, you can specify any value you prefer to be sent to the web
4770 server. If you do, it is a matter of fairness not to use any address that
4771 is actually used by a real person.
4774 This action is rarely needed, as modern web browsers don't send
4775 <quote>From:</quote> headers anymore.
4781 <term>Example usage:</term>
4784 <screen>+hide-from-header{block}</screen> or
4785 <screen>+hide-from-header{spam-me-senseless@sittingduck.example.com}</screen>
4793 <!-- ~~~~~ New section ~~~~~ -->
4794 <sect3 renderas="sect4" id="hide-referrer">
4795 <title>hide-referrer</title>
4796 <anchor id="hide-referer">
4799 <term>Typical use:</term>
4801 <para>Conceal which link you followed to get to a particular site</para>
4806 <term>Effect:</term>
4809 Deletes the <quote>Referer:</quote> (sic) HTTP header from the client request,
4810 or replaces it with a forged one.
4817 <!-- Boolean, Parameterized, Multi-value -->
4819 <para>Parameterized.</para>
4824 <term>Parameter:</term>
4828 <para><quote>conditional-block</quote> to delete the header completely if the host has changed.</para>
4831 <para><quote>conditional-forge</quote> to forge the header if the host has changed.</para>
4834 <para><quote>block</quote> to delete the header unconditionally.</para>
4837 <para><quote>forge</quote> to pretend to be coming from the homepage of the server we are talking to.</para>
4840 <para>Any other string to set a user defined referrer.</para>
4850 <literal>conditional-block</literal> is the only parameter,
4851 that isn't easily detected in the server's log file. If it blocks the
4852 referrer, the request will look like the visitor used a bookmark or
4853 typed in the address directly.
4856 Leaving the referrer unmodified for requests on the same host
4857 allows the server owner to see the visitor's <quote>click path</quote>,
4858 but in most cases she could also get that information by comparing
4859 other parts of the log file: for example the User-Agent if it isn't
4860 a very common one, or the user's IP address if it doesn't change between
4864 Always blocking the referrer, or using a custom one, can lead to
4865 failures on servers that check the referrer before they answer any
4866 requests, in an attempt to prevent their content from being
4867 embedded or linked to elsewhere.
4870 Both <literal>conditional-block</literal> and <literal>forge</literal>
4871 will work with referrer checks, as long as content and valid referring page
4872 are on the same host. Most of the time that's the case.
4875 <literal>hide-referer</literal> is an alternate spelling of
4876 <literal>hide-referrer</literal> and the two can be can be freely
4877 substituted with each other. (<quote>referrer</quote> is the
4878 correct English spelling, however the HTTP specification has a bug - it
4879 requires it to be spelled as <quote>referer</quote>.)
4885 <term>Example usage:</term>
4888 <screen>+hide-referrer{forge}</screen> or
4889 <screen>+hide-referrer{http://www.yahoo.com/}</screen>
4897 <!-- ~~~~~ New section ~~~~~ -->
4898 <sect3 renderas="sect4" id="hide-user-agent">
4899 <title>hide-user-agent</title>
4903 <term>Typical use:</term>
4905 <para>Try to conceal your type of browser and client operating system</para>
4910 <term>Effect:</term>
4913 Replaces the value of the <quote>User-Agent:</quote> HTTP header
4914 in client requests with the specified value.
4921 <!-- Boolean, Parameterized, Multi-value -->
4923 <para>Parameterized.</para>
4928 <term>Parameter:</term>
4931 Any user-defined string.
4941 This can lead to problems on web sites that depend on looking at this header in
4942 order to customize their content for different browsers (which, by the
4943 way, is <emphasis>NOT</emphasis> the right thing to do: good web sites
4944 work browser-independently).
4948 Using this action in multi-user setups or wherever different types of
4949 browsers will access the same <application>Privoxy</application> is
4950 <emphasis>not recommended</emphasis>. In single-user, single-browser
4951 setups, you might use it to delete your OS version information from
4952 the headers, because it is an invitation to exploit known bugs for your
4953 OS. It is also occasionally useful to forge this in order to access
4954 sites that won't let you in otherwise (though there may be a good
4955 reason in some cases).
4958 More information on known user-agent strings can be found at
4959 <ulink url="http://www.user-agents.org/">http://www.user-agents.org/</ulink>
4961 <ulink url="http://en.wikipedia.org/wiki/User_agent">http://en.wikipedia.org/wiki/User_agent</ulink>.
4967 <term>Example usage:</term>
4970 <screen>+hide-user-agent{Netscape 6.1 (X11; I; Linux 2.4.18 i686)}</screen>
4978 <!-- ~~~~~ New section ~~~~~ -->
4979 <sect3 renderas="sect4" id="limit-connect">
4980 <title>limit-connect</title>
4984 <term>Typical use:</term>
4986 <para>Prevent abuse of <application>Privoxy</application> as a TCP proxy relay or disable SSL for untrusted sites</para>
4991 <term>Effect:</term>
4994 Specifies to which ports HTTP CONNECT requests are allowable.
5001 <!-- Boolean, Parameterized, Multi-value -->
5003 <para>Parameterized.</para>
5008 <term>Parameter:</term>
5011 A comma-separated list of ports or port ranges (the latter using dashes, with the minimum
5012 defaulting to 0 and the maximum to 65K).
5021 By default, i.e. if no <literal>limit-connect</literal> action applies,
5022 <application>Privoxy</application> allows HTTP CONNECT requests to all
5023 ports. Use <literal>limit-connect</literal> if fine-grained control
5024 is desired for some or all destinations.
5027 The CONNECT methods exists in HTTP to allow access to secure websites
5028 (<quote>https://</quote> URLs) through proxies. It works very simply:
5029 the proxy connects to the server on the specified port, and then
5030 short-circuits its connections to the client and to the remote server.
5031 This means CONNECT-enabled proxies can be used as TCP relays very easily.
5034 <application>Privoxy</application> relays HTTPS traffic without seeing
5035 the decoded content. Websites can leverage this limitation to circumvent &my-app;'s
5036 filters. By specifying an invalid port range you can disable HTTPS entirely.
5042 <term>Example usages:</term>
5044 <!-- I had trouble getting the spacing to look right in my browser -->
5045 <!-- I probably have the wrong font setup, bollocks. -->
5046 <!-- Apparently the emphasis tag uses a proportional font no matter what -->
5048 <screen>+limit-connect{443} # Port 443 is OK.
5049 +limit-connect{80,443} # Ports 80 and 443 are OK.
5050 +limit-connect{-3, 7, 20-100, 500-} # Ports less than 3, 7, 20 to 100 and above 500 are OK.
5051 +limit-connect{-} # All ports are OK
5052 +limit-connect{,} # No HTTPS/SSL traffic is allowed</screen>
5060 <!-- ~~~~~ New section ~~~~~ -->
5061 <sect3 renderas="sect4" id="limit-cookie-lifetime">
5062 <title>limit-cookie-lifetime</title>
5066 <term>Typical use:</term>
5068 <para>Limit the lifetime of HTTP cookies to a couple of minutes or hours.</para>
5073 <term>Effect:</term>
5076 Overwrites the expires field in Set-Cookie server headers if it's above the specified limit.
5083 <!-- Boolean, Parameterized, Multi-value -->
5085 <para>Parameterized.</para>
5090 <term>Parameter:</term>
5093 The lifetime limit in minutes, or 0.
5102 This action reduces the lifetime of HTTP cookies coming from the
5103 server to the specified number of minutes, starting from the time
5104 the cookie passes Privoxy.
5107 Cookies with a lifetime below the limit are not modified.
5108 The lifetime of session cookies is set to the specified limit.
5111 The effect of this action depends on the server.
5114 In case of servers which refresh their cookies with each response
5115 (or at least frequently), the lifetime limit set by this action
5117 Thus, a session associated with the cookie continues to work with
5118 this action enabled, as long as a new request is made before the
5119 last limit set is reached.
5122 However, some servers send their cookies once, with a lifetime of several
5123 years (the year 2037 is a popular choice), and do not refresh them
5124 until a certain event in the future, for example the user logging out.
5125 In this case this action may limit the absolute lifetime of the session,
5126 even if requests are made frequently.
5129 If the parameter is <quote>0</quote>, this action behaves like
5130 <literal><link linkend="session-cookies-only">session-cookies-only</link></literal>.
5136 <term>Example usages:</term>
5139 <screen>+limit-cookie-lifetime{60}
5147 <!-- ~~~~~ New section ~~~~~ -->
5148 <sect3 renderas="sect4" id="prevent-compression">
5149 <title>prevent-compression</title>
5153 <term>Typical use:</term>
5156 Ensure that servers send the content uncompressed, so it can be
5157 passed through <literal><link linkend="filter">filter</link></literal>s.
5163 <term>Effect:</term>
5166 Removes the Accept-Encoding header which can be used to ask for compressed transfer.
5173 <!-- Boolean, Parameterized, Multi-value -->
5175 <para>Boolean.</para>
5180 <term>Parameter:</term>
5192 More and more websites send their content compressed by default, which
5193 is generally a good idea and saves bandwidth. But the <literal><link
5194 linkend="filter">filter</link></literal> and
5195 <literal><link linkend="deanimate-gifs">deanimate-gifs</link></literal>
5196 actions need access to the uncompressed data.
5199 When compiled with zlib support (available since &my-app; 3.0.7), content that should be
5200 filtered is decompressed on-the-fly and you don't have to worry about this action.
5201 If you are using an older &my-app; version, or one that hasn't been compiled with zlib
5202 support, this action can be used to convince the server to send the content uncompressed.
5205 Most text-based instances compress very well, the size is seldom decreased by less than 50%,
5206 for markup-heavy instances like news feeds saving more than 90% of the original size isn't
5210 Not using compression will therefore slow down the transfer, and you should only
5211 enable this action if you really need it. As of &my-app; 3.0.7 it's disabled in all
5212 predefined action settings.
5215 Note that some (rare) ill-configured sites don't handle requests for uncompressed
5216 documents correctly. Broken PHP applications tend to send an empty document body,
5217 some IIS versions only send the beginning of the content. If you enable
5218 <literal>prevent-compression</literal> per default, you might want to add
5219 exceptions for those sites. See the example for how to do that.
5225 <term>Example usage (sections):</term>
5229 # Selectively turn off compression, and enable a filter
5231 { +filter{tiny-textforms} +prevent-compression }
5232 # Match only these sites
5237 # Or instead, we could set a universal default:
5239 { +prevent-compression }
5242 # Then maybe make exceptions for broken sites:
5244 { -prevent-compression }
5245 .compusa.com/</screen>
5254 <!-- ~~~~~ New section ~~~~~ -->
5255 <sect3 renderas="sect4" id="overwrite-last-modified">
5256 <title>overwrite-last-modified</title>
5262 <term>Typical use:</term>
5264 <para>Prevent yet another way to track the user's steps between sessions.</para>
5269 <term>Effect:</term>
5272 Deletes the <quote>Last-Modified:</quote> HTTP server header or modifies its value.
5279 <!-- Boolean, Parameterized, Multi-value -->
5281 <para>Parameterized.</para>
5286 <term>Parameter:</term>
5289 One of the keywords: <quote>block</quote>, <quote>reset-to-request-time</quote>
5290 and <quote>randomize</quote>
5299 Removing the <quote>Last-Modified:</quote> header is useful for filter
5300 testing, where you want to force a real reload instead of getting status
5301 code <quote>304</quote>, which would cause the browser to reuse the old
5302 version of the page.
5305 The <quote>randomize</quote> option overwrites the value of the
5306 <quote>Last-Modified:</quote> header with a randomly chosen time
5307 between the original value and the current time. In theory the server
5308 could send each document with a different <quote>Last-Modified:</quote>
5309 header to track visits without using cookies. <quote>Randomize</quote>
5310 makes it impossible and the browser can still revalidate cached documents.
5313 <quote>reset-to-request-time</quote> overwrites the value of the
5314 <quote>Last-Modified:</quote> header with the current time. You could use
5315 this option together with
5316 <literal><link linkend="hide-if-modified-since">hide-if-modified-since</link></literal>
5317 to further customize your random range.
5320 The preferred parameter here is <quote>randomize</quote>. It is safe
5321 to use, as long as the time settings are more or less correct.
5322 If the server sets the <quote>Last-Modified:</quote> header to the time
5323 of the request, the random range becomes zero and the value stays the same.
5324 Therefore you should later randomize it a second time with
5325 <literal><link linkend="hide-if-modified-since">hided-if-modified-since</link></literal>,
5329 It is also recommended to use this action together with
5330 <literal><link linkend="crunch-if-none-match">crunch-if-none-match</link></literal>.
5336 <term>Example usage:</term>
5339 <screen># Let the browser revalidate without being tracked across sessions
5340 { +hide-if-modified-since{-60} \
5341 +overwrite-last-modified{randomize} \
5342 +crunch-if-none-match}
5351 <!-- ~~~~~ New section ~~~~~ -->
5352 <sect3 renderas="sect4" id="redirect">
5353 <title>redirect</title>
5359 <term>Typical use:</term>
5362 Redirect requests to other sites.
5368 <term>Effect:</term>
5371 Convinces the browser that the requested document has been moved
5372 to another location and the browser should get it from there.
5379 <!-- Boolean, Parameterized, Multi-value -->
5381 <para>Parameterized</para>
5386 <term>Parameter:</term>
5389 An absolute URL or a single pcrs command.
5398 Requests to which this action applies are answered with a
5399 HTTP redirect to URLs of your choosing. The new URL is
5400 either provided as parameter, or derived by applying a
5401 single pcrs command to the original URL.
5404 The syntax for pcrs commands is documented in the
5405 <link linkend="filter-file">filter file</link> section.
5408 Requests can't be blocked and redirected at the same time,
5409 applying this action together with
5410 <literal><link linkend="block">block</link></literal>
5411 is a configuration error. Currently the request is blocked
5412 and an error message logged, the behavior may change in the
5413 future and result in Privoxy rejecting the action file.
5416 This action can be combined with
5417 <literal><link linkend="fast-redirects">fast-redirects{check-decoded-url}</link></literal>
5418 to redirect to a decoded version of a rewritten URL.
5421 Use this action carefully, make sure not to create redirection loops
5422 and be aware that using your own redirects might make it
5423 possible to fingerprint your requests.
5426 In case of problems with your redirects, or simply to watch
5427 them working, enable <link linkend="DEBUG">debug 128</link>.
5433 <term>Example usages:</term>
5436 <screen># Replace example.com's style sheet with another one
5437 { +redirect{http://localhost/css-replacements/example.com.css} }
5438 example.com/stylesheet\.css
5440 # Create a short, easy to remember nickname for a favorite site
5441 # (relies on the browser to accept and forward invalid URLs to &my-app;)
5442 { +redirect{http://www.privoxy.org/user-manual/actions-file.html} }
5445 # Always use the expanded view for Undeadly.org articles
5446 # (Note the $ at the end of the URL pattern to make sure
5447 # the request for the rewritten URL isn't redirected as well)
5448 {+redirect{s@$@&mode=expanded@}}
5449 undeadly.org/cgi\?action=article&sid=\d*$
5451 # Redirect Google search requests to MSN
5452 {+redirect{s@^http://[^/]*/search\?q=([^&]*).*@http://search.msn.com/results.aspx?q=$1@}}
5455 # Redirect MSN search requests to Yahoo
5456 {+redirect{s@^http://[^/]*/results\.aspx\?q=([^&]*).*@http://search.yahoo.com/search?p=$1@}}
5457 search.msn.com//results\.aspx\?q=
5459 # Redirect http://example.com/&bla=fasel&toChange=foo (and any other value but "bar")
5460 # to http://example.com/&bla=fasel&toChange=bar
5462 # The URL pattern makes sure that the following request isn't redirected again.
5463 {+redirect{s@toChange=[^&]+@toChange=bar@}}
5464 example.com/.*toChange=(?!bar)
5466 # Add a shortcut to look up illumos bugs
5467 {+redirect{s@^http://i([0-9]+)/.*@https://www.illumos.org/issues/$1@}}
5468 # Redirected URL = http://i4974/
5469 # Redirect Destination = https://www.illumos.org/issues/4974
5470 i[0-9][0-9][0-9][0-9]*/
5472 # Redirect remote requests for this manual
5473 # to the local version delivered by Privoxy
5474 {+redirect{s@^http://www@http://config@}}
5475 www.privoxy.org/user-manual/</screen>
5484 <!-- ~~~~~ New section ~~~~~ -->
5485 <sect3 renderas="sect4" id="server-header-filter">
5486 <title>server-header-filter</title>
5490 <term>Typical use:</term>
5493 Rewrite or remove single server headers.
5499 <term>Effect:</term>
5502 All server headers to which this action applies are filtered on-the-fly
5503 through the specified regular expression based substitutions.
5510 <!-- boolean, parameterized, Multi-value -->
5512 <para>Multi-value.</para>
5517 <term>Parameter:</term>
5520 The name of a server-header filter, as defined in one of the
5521 <link linkend="filter-file">filter files</link>.
5530 Server-header filters are applied to each header on its own, not to
5531 all at once. This makes it easier to diagnose problems, but on the downside
5532 you can't write filters that only change header x if header y's value is z.
5533 You can do that by using tags though.
5536 Server-header filters are executed after the other header actions have finished
5537 and use their output as input.
5540 Please refer to the <link linkend="filter-file">filter file chapter</link>
5541 to learn which server-header filters are available by default, and how to
5548 <term>Example usage (section):</term>
5552 {+server-header-filter{html-to-xml}}
5553 example.org/xml-instance-that-is-delivered-as-html
5555 {+server-header-filter{xml-to-html}}
5556 example.org/instance-that-is-delivered-as-xml-but-is-not
5566 <!-- ~~~~~ New section ~~~~~ -->
5567 <sect3 renderas="sect4" id="server-header-tagger">
5568 <title>server-header-tagger</title>
5572 <term>Typical use:</term>
5575 Enable or disable filters based on the Content-Type header.
5581 <term>Effect:</term>
5584 Server headers to which this action applies are filtered on-the-fly through
5585 the specified regular expression based substitutions, the result is used as
5593 <!-- boolean, parameterized, Multi-value -->
5595 <para>Multi-value.</para>
5600 <term>Parameter:</term>
5603 The name of a server-header tagger, as defined in one of the
5604 <link linkend="filter-file">filter files</link>.
5613 Server-header taggers are applied to each header on its own,
5614 and as the header isn't modified, each tagger <quote>sees</quote>
5618 Server-header taggers are executed before all other header actions
5619 that modify server headers. Their tags can be used to control
5620 all of the other server-header actions, the content filters
5621 and the crunch actions (<link linkend="redirect">redirect</link>
5622 and <link linkend="block">block</link>).
5625 Obviously crunching based on tags created by server-header taggers
5626 doesn't prevent the request from showing up in the server's log file.
5633 <term>Example usage (section):</term>
5637 # Tag every request with the content type declared by the server
5638 {+server-header-tagger{content-type}}
5641 # If the response has a tag starting with 'image/' enable an external
5642 # filter that only applies to images.
5644 # Note that the filter is not available by default, it's just a
5645 # <literal><link linkend="external-filter-syntax">silly example</link></literal>.
5646 {+external-filter{rotate-image} +force-text-mode}
5657 <!-- ~~~~~ New section ~~~~~ -->
5658 <sect3 renderas="sect4" id="session-cookies-only">
5659 <title>session-cookies-only</title>
5663 <term>Typical use:</term>
5666 Allow only temporary <quote>session</quote> cookies (for the current
5667 browser session <emphasis>only</emphasis>).
5673 <term>Effect:</term>
5676 Deletes the <quote>expires</quote> field from <quote>Set-Cookie:</quote>
5677 server headers. Most browsers will not store such cookies permanently and
5678 forget them in between sessions.
5685 <!-- Boolean, Parameterized, Multi-value -->
5687 <para>Boolean.</para>
5692 <term>Parameter:</term>
5704 This is less strict than <literal><link linkend="crunch-incoming-cookies">crunch-incoming-cookies</link></literal> /
5705 <literal><link linkend="crunch-outgoing-cookies">crunch-outgoing-cookies</link></literal> and allows you to browse
5706 websites that insist or rely on setting cookies, without compromising your privacy too badly.
5709 Most browsers will not permanently store cookies that have been processed by
5710 <literal>session-cookies-only</literal> and will forget about them between sessions.
5711 This makes profiling cookies useless, but won't break sites which require cookies so
5712 that you can log in for transactions. This is generally turned on for all
5713 sites, and is the recommended setting.
5716 It makes <emphasis>no sense at all</emphasis> to use <literal>session-cookies-only</literal>
5717 together with <literal><link linkend="crunch-incoming-cookies">crunch-incoming-cookies</link></literal> or
5718 <literal><link linkend="crunch-outgoing-cookies">crunch-outgoing-cookies</link></literal>. If you do, cookies
5719 will be plainly killed.
5722 Note that it is up to the browser how it handles such cookies without an <quote>expires</quote>
5723 field. If you use an exotic browser, you might want to try it out to be sure.
5726 This setting also has no effect on cookies that may have been stored
5727 previously by the browser before starting <application>Privoxy</application>.
5728 These would have to be removed manually.
5731 <application>Privoxy</application> also uses
5732 the <link linkend="filter-content-cookies">content-cookies filter</link>
5733 to block some types of cookies. Content cookies are not effected by
5734 <literal>session-cookies-only</literal>.
5740 <term>Example usage:</term>
5743 <screen>+session-cookies-only</screen>
5751 <!-- ~~~~~ New section ~~~~~ -->
5752 <sect3 renderas="sect4" id="set-image-blocker">
5753 <title>set-image-blocker</title>
5757 <term>Typical use:</term>
5759 <para>Choose the replacement for blocked images</para>
5764 <term>Effect:</term>
5767 This action alone doesn't do anything noticeable. If <emphasis>both</emphasis>
5768 <literal><link linkend="block">block</link></literal> <emphasis>and</emphasis> <literal><link
5769 linkend="handle-as-image">handle-as-image</link></literal> <emphasis>also</emphasis>
5770 apply, i.e. if the request is to be blocked as an image,
5771 <emphasis>then</emphasis> the parameter of this action decides what will be
5772 sent as a replacement.
5779 <!-- Boolean, Parameterized, Multi-value -->
5781 <para>Parameterized.</para>
5786 <term>Parameter:</term>
5791 <quote>pattern</quote> to send a built-in checkerboard pattern image. The image is visually
5792 decent, scales very well, and makes it obvious where banners were busted.
5797 <quote>blank</quote> to send a built-in transparent image. This makes banners disappear
5798 completely, but makes it hard to detect where <application>Privoxy</application> has blocked
5799 images on a given page and complicates troubleshooting if <application>Privoxy</application>
5800 has blocked innocent images, like navigation icons.
5805 <quote><replaceable class="parameter">target-url</replaceable></quote> to
5806 send a redirect to <replaceable class="parameter">target-url</replaceable>. You can redirect
5807 to any image anywhere, even in your local filesystem via <quote>file:///</quote> URL.
5808 (But note that not all browsers support redirecting to a local file system).
5811 A good application of redirects is to use special <application>Privoxy</application>-built-in
5812 URLs, which send the built-in images, as <replaceable class="parameter">target-url</replaceable>.
5813 This has the same visual effect as specifying <quote>blank</quote> or <quote>pattern</quote> in
5814 the first place, but enables your browser to cache the replacement image, instead of requesting
5815 it over and over again.
5826 The URLs for the built-in images are <quote>http://config.privoxy.org/send-banner?type=<replaceable
5827 class="parameter">type</replaceable></quote>, where <replaceable class="parameter">type</replaceable> is
5828 either <quote>blank</quote> or <quote>pattern</quote>.
5831 There is a third (advanced) type, called <quote>auto</quote>. It is <emphasis>NOT</emphasis> to be
5832 used in <literal>set-image-blocker</literal>, but meant for use from <link linkend="filter-file">filters</link>.
5833 Auto will select the type of image that would have applied to the referring page, had it been an image.
5839 <term>Example usage:</term>
5845 <screen>+set-image-blocker{pattern}</screen>
5848 Redirect to the BSD daemon:
5851 <screen>+set-image-blocker{http://www.freebsd.org/gifs/dae_up3.gif}</screen>
5854 Redirect to the built-in pattern for better caching:
5857 <screen>+set-image-blocker{http://config.privoxy.org/send-banner?type=pattern}</screen>
5865 <!-- ~~~~~ New section ~~~~~ -->
5867 <title>Summary</title>
5869 Note that many of these actions have the potential to cause a page to
5870 misbehave, possibly even not to display at all. There are many ways
5871 a site designer may choose to design his site, and what HTTP header
5872 content, and other criteria, he may depend on. There is no way to have hard
5873 and fast rules for all sites. See the <link
5874 linkend="ACTIONSANAT">Appendix</link> for a brief example on troubleshooting
5880 <!-- ~~~~~ New section ~~~~~ -->
5881 <sect2 id="aliases">
5882 <title>Aliases</title>
5884 Custom <quote>actions</quote>, known to <application>Privoxy</application>
5885 as <quote>aliases</quote>, can be defined by combining other actions.
5886 These can in turn be invoked just like the built-in actions.
5887 Currently, an alias name can contain any character except space, tab,
5889 <quote>{</quote> and <quote>}</quote>, but we <emphasis>strongly
5890 recommend</emphasis> that you only use <quote>a</quote> to <quote>z</quote>,
5891 <quote>0</quote> to <quote>9</quote>, <quote>+</quote>, and <quote>-</quote>.
5892 Alias names are not case sensitive, and are not required to start with a
5893 <quote>+</quote> or <quote>-</quote> sign, since they are merely textually
5897 Aliases can be used throughout the actions file, but they <emphasis>must be
5898 defined in a special section at the top of the file!</emphasis>
5899 And there can only be one such section per actions file. Each actions file may
5900 have its own alias section, and the aliases defined in it are only visible
5904 There are two main reasons to use aliases: One is to save typing for frequently
5905 used combinations of actions, the other one is a gain in flexibility: If you
5906 decide once how you want to handle shops by defining an alias called
5907 <quote>shop</quote>, you can later change your policy on shops in
5908 <emphasis>one</emphasis> place, and your changes will take effect everywhere
5909 in the actions file where the <quote>shop</quote> alias is used. Calling aliases
5910 by their purpose also makes your actions files more readable.
5913 Currently, there is one big drawback to using aliases, though:
5914 <application>Privoxy</application>'s built-in web-based action file
5915 editor honors aliases when reading the actions files, but it expands
5916 them before writing. So the effects of your aliases are of course preserved,
5917 but the aliases themselves are lost when you edit sections that use aliases
5922 Now let's define some aliases...
5927 # Useful custom aliases we can use later.
5929 # Note the (required!) section header line and that this section
5930 # must be at the top of the actions file!
5934 # These aliases just save typing later:
5935 # (Note that some already use other aliases!)
5937 +crunch-all-cookies = +<link linkend="CRUNCH-INCOMING-COOKIES">crunch-incoming-cookies</link> +<link linkend="CRUNCH-OUTGOING-COOKIES">crunch-outgoing-cookies</link>
5938 -crunch-all-cookies = -<link linkend="CRUNCH-INCOMING-COOKIES">crunch-incoming-cookies</link> -<link linkend="CRUNCH-OUTGOING-COOKIES">crunch-outgoing-cookies</link>
5939 +block-as-image = +block{Blocked image.} +handle-as-image
5940 allow-all-cookies = -crunch-all-cookies -<link linkend="SESSION-COOKIES-ONLY">session-cookies-only</link> -<link linkend="FILTER-CONTENT-COOKIES">filter{content-cookies}</link>
5942 # These aliases define combinations of actions
5943 # that are useful for certain types of sites:
5945 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>
5947 shop = -crunch-all-cookies -<link linkend="FILTER-ALL-POPUPS">filter{all-popups}</link>
5949 # Short names for other aliases, for really lazy people ;-)
5951 c0 = +crunch-all-cookies
5952 c1 = -crunch-all-cookies</screen>
5956 ...and put them to use. These sections would appear in the lower part of an
5957 actions file and define exceptions to the default actions (as specified further
5958 up for the <quote>/</quote> pattern):
5963 # These sites are either very complex or very keen on
5964 # user data and require minimal interference to work:
5967 .office.microsoft.com
5968 .windowsupdate.microsoft.com
5969 # Gmail is really mail.google.com, not gmail.com
5973 # Allow cookies (for setting and retrieving your customer data)
5977 .worldpay.com # for quietpc.com
5980 # These shops require pop-ups:
5982 {-filter{all-popups} -filter{unsolicited-popups}}
5984 .overclockers.co.uk</screen>
5988 Aliases like <quote>shop</quote> and <quote>fragile</quote> are typically used for
5989 <quote>problem</quote> sites that require more than one action to be disabled
5990 in order to function properly.
5996 <!-- ~~~~~ New section ~~~~~ -->
5997 <sect2 id="act-examples">
5998 <title>Actions Files Tutorial</title>
6000 The above chapters have shown <link linkend="actions-file">which actions files
6001 there are and how they are organized</link>, how actions are <link
6002 linkend="actions">specified</link> and <link linkend="actions-apply">applied
6003 to URLs</link>, how <link linkend="af-patterns">patterns</link> work, and how to
6004 define and use <link linkend="aliases">aliases</link>. Now, let's look at an
6005 example <filename>match-all.action</filename>, <filename>default.action</filename>
6006 and <filename>user.action</filename> file and see how all these pieces come together:
6010 <title>match-all.action</title>
6012 Remember <emphasis>all actions are disabled when matching starts</emphasis>,
6013 so we have to explicitly enable the ones we want.
6017 While the <filename>match-all.action</filename> file only contains a
6018 single section, it is probably the most important one. It has only one
6019 pattern, <quote><literal>/</literal></quote>, but this pattern
6020 <link linkend="af-patterns">matches all URLs</link>. Therefore, the set of
6021 actions used in this <quote>default</quote> section <emphasis>will
6022 be applied to all requests as a start</emphasis>. It can be partly or
6023 wholly overridden by other actions files like <filename>default.action</filename>
6024 and <filename>user.action</filename>, but it will still be largely responsible
6025 for your overall browsing experience.
6029 Again, at the start of matching, all actions are disabled, so there is
6030 no need to disable any actions here. (Remember: a <quote>+</quote>
6031 preceding the action name enables the action, a <quote>-</quote> disables!).
6032 Also note how this long line has been made more readable by splitting it into
6033 multiple lines with line continuation.
6039 +<link linkend="CHANGE-X-FORWARDED-FOR">change-x-forwarded-for{block}</link> \
6040 +<link linkend="HIDE-FROM-HEADER">hide-from-header{block}</link> \
6041 +<link linkend="SET-IMAGE-BLOCKER">set-image-blocker{pattern}</link> \
6048 The default behavior is now set.
6053 <title>default.action</title>
6056 If you aren't a developer, there's no need for you to edit the
6057 <filename>default.action</filename> file. It is maintained by
6058 the &my-app; developers and if you disagree with some of the
6059 sections, you should overrule them in your <filename>user.action</filename>.
6063 Understanding the <filename>default.action</filename> file can
6064 help you with your <filename>user.action</filename>, though.
6068 The first section in this file is a special section for internal use
6069 that prevents older &my-app; versions from reading the file:
6074 ##########################################################################
6075 # Settings -- Don't change! For internal Privoxy use ONLY.
6076 ##########################################################################
6078 for-privoxy-version=3.0.11</screen>
6082 After that comes the (optional) alias section. We'll use the example
6083 section from the above <link linkend="aliases">chapter on aliases</link>,
6084 that also explains why and how aliases are used:
6089 ##########################################################################
6091 ##########################################################################
6094 # These aliases just save typing later:
6095 # (Note that some already use other aliases!)
6097 +crunch-all-cookies = +<link linkend="CRUNCH-INCOMING-COOKIES">crunch-incoming-cookies</link> +<link linkend="CRUNCH-OUTGOING-COOKIES">crunch-outgoing-cookies</link>
6098 -crunch-all-cookies = -<link linkend="CRUNCH-INCOMING-COOKIES">crunch-incoming-cookies</link> -<link linkend="CRUNCH-OUTGOING-COOKIES">crunch-outgoing-cookies</link>
6099 +block-as-image = +block{Blocked image.} +handle-as-image
6100 mercy-for-cookies = -crunch-all-cookies -<link linkend="SESSION-COOKIES-ONLY">session-cookies-only</link> -<link linkend="FILTER-CONTENT-COOKIES">filter{content-cookies}</link>
6102 # These aliases define combinations of actions
6103 # that are useful for certain types of sites:
6105 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>
6106 shop = -crunch-all-cookies -<link linkend="FILTER-ALL-POPUPS">filter{all-popups}</link></screen>
6110 The first of our specialized sections is concerned with <quote>fragile</quote>
6111 sites, i.e. sites that require minimum interference, because they are either
6112 very complex or very keen on tracking you (and have mechanisms in place that
6113 make them unusable for people who avoid being tracked). We will simply use
6114 our pre-defined <literal>fragile</literal> alias instead of stating the list
6115 of actions explicitly:
6120 ##########################################################################
6121 # Exceptions for sites that'll break under the default action set:
6122 ##########################################################################
6124 # "Fragile" Use a minimum set of actions for these sites (see alias above):
6127 .office.microsoft.com # surprise, surprise!
6128 .windowsupdate.microsoft.com
6129 mail.google.com</screen>
6133 Shopping sites are not as fragile, but they typically
6134 require cookies to log in, and pop-up windows for shopping
6135 carts or item details. Again, we'll use a pre-defined alias:
6144 .worldpay.com # for quietpc.com
6146 .scan.co.uk</screen>
6150 The <literal><link linkend="FAST-REDIRECTS">fast-redirects</link></literal>
6151 action, which may have been enabled in <filename>match-all.action</filename>,
6152 breaks some sites. So disable it for popular sites where we know it misbehaves:
6157 { -<link linkend="FAST-REDIRECTS">fast-redirects</link> }
6161 .altavista.com/.*(like|url|link):http
6162 .altavista.com/trans.*urltext=http
6163 .nytimes.com</screen>
6167 It is important that <application>Privoxy</application> knows which
6168 URLs belong to images, so that <emphasis>if</emphasis> they are to
6169 be blocked, a substitute image can be sent, rather than an HTML page.
6170 Contacting the remote site to find out is not an option, since it
6171 would destroy the loading time advantage of banner blocking, and it
6172 would feed the advertisers information about you. We can mark any
6173 URL as an image with the <literal><link
6174 linkend="handle-as-image">handle-as-image</link></literal> action,
6175 and marking all URLs that end in a known image file extension is a
6181 ##########################################################################
6183 ##########################################################################
6185 # Define which file types will be treated as images, in case they get
6186 # blocked further down this file:
6188 { +<link linkend="HANDLE-AS-IMAGE">handle-as-image</link> }
6189 /.*\.(gif|jpe?g|png|bmp|ico)$</screen>
6193 And then there are known banner sources. They often use scripts to
6194 generate the banners, so it won't be visible from the URL that the
6195 request is for an image. Hence we block them <emphasis>and</emphasis>
6196 mark them as images in one go, with the help of our
6197 <literal>+block-as-image</literal> alias defined above. (We could of
6198 course just as well use <literal>+<link linkend="block">block</link>
6199 +<link linkend="handle-as-image">handle-as-image</link></literal> here.)
6200 Remember that the type of the replacement image is chosen by the
6201 <literal><link linkend="set-image-blocker">set-image-blocker</link></literal>
6202 action. Since all URLs have matched the default section with its
6203 <literal>+<link linkend="set-image-blocker">set-image-blocker</link>{pattern}</literal>
6204 action before, it still applies and needn't be repeated:
6209 # Known ad generators:
6214 .ad.*.doubleclick.net
6215 .a.yimg.com/(?:(?!/i/).)*$
6216 .a[0-9].yimg.com/(?:(?!/i/).)*$
6222 One of the most important jobs of <application>Privoxy</application>
6223 is to block banners. Many of these can be <quote>blocked</quote>
6224 by the <literal><link linkend="filter">filter</link>{banners-by-size}</literal>
6225 action, which we enabled above, and which deletes the references to banner
6226 images from the pages while they are loaded, so the browser doesn't request
6227 them anymore, and hence they don't need to be blocked here. But this naturally
6228 doesn't catch all banners, and some people choose not to use filters, so we
6229 need a comprehensive list of patterns for banner URLs here, and apply the
6230 <literal><link linkend="block">block</link></literal> action to them.
6233 First comes many generic patterns, which do most of the work, by
6234 matching typical domain and path name components of banners. Then comes
6235 a list of individual patterns for specific sites, which is omitted here
6236 to keep the example short:
6241 ##########################################################################
6242 # Block these fine banners:
6243 ##########################################################################
6244 { <link linkend="BLOCK">+block{Banner ads.}</link> }
6252 /.*count(er)?\.(pl|cgi|exe|dll|asp|php[34]?)
6253 /(?:.*/)?(publicite|werbung|rekla(ma|me|am)|annonse|maino(kset|nta|s)?)/
6255 # Site-specific patterns (abbreviated):
6257 .hitbox.com</screen>
6261 It's quite remarkable how many advertisers actually call their banner
6262 servers ads.<replaceable>company</replaceable>.com, or call the directory
6263 in which the banners are stored simply <quote>banners</quote>. So the above
6264 generic patterns are surprisingly effective.
6267 But being very generic, they necessarily also catch URLs that we don't want
6268 to block. The pattern <literal>.*ads.</literal> e.g. catches
6269 <quote>nasty-<emphasis>ads</emphasis>.nasty-corp.com</quote> as intended,
6270 but also <quote>downlo<emphasis>ads</emphasis>.sourcefroge.net</quote> or
6271 <quote><emphasis>ads</emphasis>l.some-provider.net.</quote> So here come some
6272 well-known exceptions to the <literal>+<link linkend="BLOCK">block</link></literal>
6276 Note that these are exceptions to exceptions from the default! Consider the URL
6277 <quote>downloads.sourcefroge.net</quote>: Initially, all actions are deactivated,
6278 so it wouldn't get blocked. Then comes the defaults section, which matches the
6279 URL, but just deactivates the <literal><link linkend="BLOCK">block</link></literal>
6280 action once again. Then it matches <literal>.*ads.</literal>, an exception to the
6281 general non-blocking policy, and suddenly
6282 <literal><link linkend="BLOCK">+block</link></literal> applies. And now, it'll match
6283 <literal>.*loads.</literal>, where <literal><link linkend="BLOCK">-block</link></literal>
6284 applies, so (unless it matches <emphasis>again</emphasis> further down) it ends up
6285 with no <literal><link linkend="BLOCK">block</link></literal> action applying.
6290 ##########################################################################
6291 # Save some innocent victims of the above generic block patterns:
6292 ##########################################################################
6296 { -<link linkend="BLOCK">block</link> }
6297 adv[io]*. # (for advogato.org and advice.*)
6298 adsl. # (has nothing to do with ads)
6299 adobe. # (has nothing to do with ads either)
6300 ad[ud]*. # (adult.* and add.*)
6301 .edu # (universities don't host banners (yet!))
6302 .*loads. # (downloads, uploads etc)
6310 www.globalintersec.com/adv # (adv = advanced)
6311 www.ugu.com/sui/ugu/adv</screen>
6315 Filtering source code can have nasty side effects,
6316 so make an exception for our friends at sourceforge.net,
6317 and all paths with <quote>cvs</quote> in them. Note that
6318 <literal>-<link linkend="FILTER">filter</link></literal>
6319 disables <emphasis>all</emphasis> filters in one fell swoop!
6324 # Don't filter code!
6326 { -<link linkend="FILTER">filter</link> }
6331 .sourceforge.net</screen>
6335 The actual <filename>default.action</filename> is of course much more
6336 comprehensive, but we hope this example made clear how it works.
6341 <sect3><title>user.action</title>
6344 So far we are painting with a broad brush by setting general policies,
6345 which would be a reasonable starting point for many people. Now,
6346 you might want to be more specific and have customized rules that
6347 are more suitable to your personal habits and preferences. These would
6348 be for narrowly defined situations like your ISP or your bank, and should
6349 be placed in <filename>user.action</filename>, which is parsed after all other
6350 actions files and hence has the last word, over-riding any previously
6351 defined actions. <filename>user.action</filename> is also a
6352 <emphasis>safe</emphasis> place for your personal settings, since
6353 <filename>default.action</filename> is actively maintained by the
6354 <application>Privoxy</application> developers and you'll probably want
6355 to install updated versions from time to time.
6359 So let's look at a few examples of things that one might typically do in
6360 <filename>user.action</filename>:
6364 <!-- brief sample user.action here -->
6368 # My user.action file. <fred@example.com></screen>
6372 As <link linkend="aliases">aliases</link> are local to the actions
6373 file that they are defined in, you can't use the ones from
6374 <filename>default.action</filename>, unless you repeat them here:
6379 # Aliases are local to the file they are defined in.
6380 # (Re-)define aliases for this file:
6384 # These aliases just save typing later, and the alias names should
6385 # be self explanatory.
6387 +crunch-all-cookies = +crunch-incoming-cookies +crunch-outgoing-cookies
6388 -crunch-all-cookies = -crunch-incoming-cookies -crunch-outgoing-cookies
6389 allow-all-cookies = -crunch-all-cookies -session-cookies-only
6390 allow-popups = -filter{all-popups}
6391 +block-as-image = +block{Blocked as image.} +handle-as-image
6392 -block-as-image = -block
6394 # These aliases define combinations of actions that are useful for
6395 # certain types of sites:
6397 fragile = -block -crunch-all-cookies -filter -fast-redirects -hide-referrer
6398 shop = -crunch-all-cookies allow-popups
6400 # Allow ads for selected useful free sites:
6402 allow-ads = -block -filter{banners-by-size} -filter{banners-by-link}
6404 # Alias for specific file types that are text, but might have conflicting
6405 # MIME types. We want the browser to force these to be text documents.
6406 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>
6411 Say you have accounts on some sites that you visit regularly, and
6412 you don't want to have to log in manually each time. So you'd like
6413 to allow persistent cookies for these sites. The
6414 <literal>allow-all-cookies</literal> alias defined above does exactly
6415 that, i.e. it disables crunching of cookies in any direction, and the
6416 processing of cookies to make them only temporary.
6421 { allow-all-cookies }
6425 .redhat.com</screen>
6429 Your bank is allergic to some filter, but you don't know which, so you disable them all:
6434 { -<link linkend="FILTER">filter</link> }
6435 .your-home-banking-site.com</screen>
6439 Some file types you may not want to filter for various reasons:
6444 # Technical documentation is likely to contain strings that might
6445 # erroneously get altered by the JavaScript-oriented filters:
6450 # And this stupid host sends streaming video with a wrong MIME type,
6451 # so that Privoxy thinks it is getting HTML and starts filtering:
6453 stupid-server.example.com/</screen>
6457 Example of a simple <link linkend="BLOCK">block</link> action. Say you've
6458 seen an ad on your favourite page on example.com that you want to get rid of.
6459 You have right-clicked the image, selected <quote>copy image location</quote>
6460 and pasted the URL below while removing the leading http://, into a
6461 <literal>{ +block{} }</literal> section. Note that <literal>{ +handle-as-image
6462 }</literal> need not be specified, since all URLs ending in
6463 <literal>.gif</literal> will be tagged as images by the general rules as set
6464 in default.action anyway:
6469 { +<link linkend="BLOCK">block</link>{Nasty ads.} }
6470 www.example.com/nasty-ads/sponsor\.gif
6471 another.example.net/more/junk/here/</screen>
6475 The URLs of dynamically generated banners, especially from large banner
6476 farms, often don't use the well-known image file name extensions, which
6477 makes it impossible for <application>Privoxy</application> to guess
6478 the file type just by looking at the URL.
6479 You can use the <literal>+block-as-image</literal> alias defined above for
6481 Note that objects which match this rule but then turn out NOT to be an
6482 image are typically rendered as a <quote>broken image</quote> icon by the
6483 browser. Use cautiously.
6492 ar.atwola.com/</screen>
6496 Now you noticed that the default configuration breaks Forbes Magazine,
6497 but you were too lazy to find out which action is the culprit, and you
6498 were again too lazy to give <link linkend="contact">feedback</link>, so
6499 you just used the <literal>fragile</literal> alias on the site, and
6500 -- <emphasis>whoa!</emphasis> -- it worked. The <literal>fragile</literal>
6501 aliases disables those actions that are most likely to break a site. Also,
6502 good for testing purposes to see if it is <application>Privoxy</application>
6503 that is causing the problem or not. We later find other regular sites
6504 that misbehave, and add those to our personalized list of troublemakers:
6512 .mybank.com</screen>
6516 You like the <quote>fun</quote> text replacements in <filename>default.filter</filename>,
6517 but it is disabled in the distributed actions file.
6518 So you'd like to turn it on in your private,
6519 update-safe config, once and for all:
6524 { +<link linkend="filter-fun">filter{fun}</link> }
6525 / # For ALL sites!</screen>
6529 Note that the above is not really a good idea: There are exceptions
6530 to the filters in <filename>default.action</filename> for things that
6531 really shouldn't be filtered, like code on CVS->Web interfaces. Since
6532 <filename>user.action</filename> has the last word, these exceptions
6533 won't be valid for the <quote>fun</quote> filtering specified here.
6537 You might also worry about how your favourite free websites are
6538 funded, and find that they rely on displaying banner advertisements
6539 to survive. So you might want to specifically allow banners for those
6540 sites that you feel provide value to you:
6552 Note that <literal>allow-ads</literal> has been aliased to
6553 <literal>-<link linkend="block">block</link></literal>,
6554 <literal>-<link linkend="filter-banners-by-size">filter{banners-by-size}</link></literal>, and
6555 <literal>-<link linkend="filter-banners-by-link">filter{banners-by-link}</link></literal> above.
6559 Invoke another alias here to force an over-ride of the MIME type <literal>
6560 application/x-sh</literal> which typically would open a download type
6561 dialog. In my case, I want to look at the shell script, and then I can save
6562 it should I choose to.
6572 <filename>user.action</filename> is generally the best place to define
6573 exceptions and additions to the default policies of
6574 <filename>default.action</filename>. Some actions are safe to have their
6575 default policies set here though. So let's set a default policy to have a
6576 <quote>blank</quote> image as opposed to the checkerboard pattern for
6577 <emphasis>ALL</emphasis> sites. <quote>/</quote> of course matches all URL
6583 { +<link linkend="set-image-blocker">set-image-blocker{blank}</link> }
6584 / # ALL sites</screen>
6590 <!-- ~ End section ~ -->
6594 <!-- ~ End section ~ -->
6596 <!-- ~~~~~~~~ New section Header ~~~~~~~~~ -->
6598 <sect1 id="filter-file">
6599 <title>Filter Files</title>
6602 On-the-fly text substitutions need
6603 to be defined in a <quote>filter file</quote>. Once defined, they
6604 can then be invoked as an <quote>action</quote>.
6608 &my-app; supports three different pcrs-based filter actions:
6609 <literal><link linkend="filter">filter</link></literal> to
6610 rewrite the content that is send to the client,
6611 <literal><link linkend="client-header-filter">client-header-filter</link></literal>
6612 to rewrite headers that are send by the client, and
6613 <literal><link linkend="server-header-filter">server-header-filter</link></literal>
6614 to rewrite headers that are send by the server.
6618 &my-app; also supports two tagger actions:
6619 <literal><link linkend="client-header-tagger">client-header-tagger</link></literal>
6621 <literal><link linkend="server-header-tagger">server-header-tagger</link></literal>.
6622 Taggers and filters use the same syntax in the filter files, the difference
6623 is that taggers don't modify the text they are filtering, but use a rewritten
6624 version of the filtered text as tag. The tags can then be used to change the
6625 applying actions through sections with <link linkend="tag-pattern">tag-patterns</link>.
6629 Finally &my-app; supports the
6630 <literal><link linkend="external-filter">external-filter</link></literal> action
6631 to enable <literal><link linkend="external-filter-syntax">external filters</link></literal>
6632 written in proper programming languages.
6637 Multiple filter files can be defined through the <literal> <link
6638 linkend="filterfile">filterfile</link></literal> config directive. The filters
6639 as supplied by the developers are located in
6640 <filename>default.filter</filename>. It is recommended that any locally
6641 defined or modified filters go in a separately defined file such as
6642 <filename>user.filter</filename>.
6646 Common tasks for content filters are to eliminate common annoyances in
6647 HTML and JavaScript, such as pop-up windows,
6648 exit consoles, crippled windows without navigation tools, the
6649 infamous <BLINK> tag etc, to suppress images with certain
6650 width and height attributes (standard banner sizes or web-bugs),
6651 or just to have fun.
6655 Enabled content filters are applied to any content whose
6656 <quote>Content Type</quote> header is recognised as a sign
6657 of text-based content, with the exception of <literal>text/plain</literal>.
6658 Use the <link linkend="FORCE-TEXT-MODE">force-text-mode</link> action
6659 to also filter other content.
6663 Substitutions are made at the source level, so if you want to <quote>roll
6664 your own</quote> filters, you should first be familiar with HTML syntax,
6665 and, of course, regular expressions.
6669 Just like the <link linkend="actions-file">actions files</link>, the
6670 filter file is organized in sections, which are called <emphasis>filters</emphasis>
6671 here. Each filter consists of a heading line, that starts with one of the
6672 <emphasis>keywords</emphasis> <literal>FILTER:</literal>,
6673 <literal>CLIENT-HEADER-FILTER:</literal> or <literal>SERVER-HEADER-FILTER:</literal>
6674 followed by the filter's <emphasis>name</emphasis>, and a short (one line)
6675 <emphasis>description</emphasis> of what it does. Below that line
6676 come the <emphasis>jobs</emphasis>, i.e. lines that define the actual
6677 text substitutions. By convention, the name of a filter
6678 should describe what the filter <emphasis>eliminates</emphasis>. The
6679 comment is used in the <ulink url="http://config.privoxy.org/">web-based
6680 user interface</ulink>.
6684 Once a filter called <replaceable>name</replaceable> has been defined
6685 in the filter file, it can be invoked by using an action of the form
6686 +<literal><link linkend="filter">filter</link>{<replaceable>name</replaceable>}</literal>
6687 in any <link linkend="actions-file">actions file</link>.
6691 Filter definitions start with a header line that contains the filter
6692 type, the filter name and the filter description.
6693 A content filter header line for a filter called <quote>foo</quote> could look
6698 <screen>FILTER: foo Replace all "foo" with "bar"</screen>
6702 Below that line, and up to the next header line, come the jobs that
6703 define what text replacements the filter executes. They are specified
6704 in a syntax that imitates <ulink url="http://www.perl.org/">Perl</ulink>'s
6705 <literal>s///</literal> operator. If you are familiar with Perl, you
6706 will find this to be quite intuitive, and may want to look at the
6707 PCRS documentation for the subtle differences to Perl behaviour.
6711 Most notably, the non-standard option letter <literal>U</literal> is supported,
6712 which turns the default to ungreedy matching (add <literal>?</literal> to
6713 quantifiers to turn them greedy again).
6717 The non-standard option letter <literal>D</literal> (dynamic) allows
6718 to use the variables $host, $origin (the IP address the request came from),
6719 $path and $url. They will be replaced with the value they refer to before
6720 the filter is executed.
6724 Note that '$' is a bad choice for a delimiter in a dynamic filter as you
6725 might end up with unintended variables if you use a variable name
6726 directly after the delimiter. Variables will be resolved without
6727 escaping anything, therefore you also have to be careful not to chose
6728 delimiters that appear in the replacement text. For example '<' should
6729 be save, while '?' will sooner or later cause conflicts with $url.
6733 The non-standard option letter <literal>T</literal> (trivial) prevents
6734 parsing for backreferences in the substitute. Use it if you want to include
6735 text like '$&' in your substitute without quoting.
6740 <ulink url="http://en.wikipedia.org/wiki/Regular_expressions"><quote>Regular
6741 Expressions</quote></ulink>, you might want to take a look at
6742 the <link linkend="regex">Appendix on regular expressions</link>, and
6743 see the <ulink url="http://perldoc.perl.org/perlre.html">Perl
6745 <ulink url="http://perldoc.perl.org/perlop.html">the
6746 <literal>s///</literal> operator's syntax</ulink> and <ulink
6747 url="http://perldoc.perl.org/perlre.html">Perl-style regular
6748 expressions</ulink> in general.
6749 The below examples might also help to get you started.
6753 <!-- ~~~~~~~~ New section Header ~~~~~~~~~ -->
6755 <sect2><title>Filter File Tutorial</title>
6757 Now, let's complete our <quote>foo</quote> content filter. We have already defined
6758 the heading, but the jobs are still missing. Since all it does is to replace
6759 <quote>foo</quote> with <quote>bar</quote>, there is only one (trivial) job
6764 <screen>s/foo/bar/</screen>
6768 But wait! Didn't the comment say that <emphasis>all</emphasis> occurrences
6769 of <quote>foo</quote> should be replaced? Our current job will only take
6770 care of the first <quote>foo</quote> on each page. For global substitution,
6771 we'll need to add the <literal>g</literal> option:
6775 <screen>s/foo/bar/g</screen>
6779 Our complete filter now looks like this:
6782 <screen>FILTER: foo Replace all "foo" with "bar"
6783 s/foo/bar/g</screen>
6787 Let's look at some real filters for more interesting examples. Here you see
6788 a filter that protects against some common annoyances that arise from JavaScript
6789 abuse. Let's look at its jobs one after the other:
6795 FILTER: js-annoyances Get rid of particularly annoying JavaScript abuse
6797 # Get rid of JavaScript referrer tracking. Test page: http://www.randomoddness.com/untitled.htm
6799 s|(<script.*)document\.referrer(.*</script>)|$1"Not Your Business!"$2|Usg</screen>
6803 Following the header line and a comment, you see the job. Note that it uses
6804 <literal>|</literal> as the delimiter instead of <literal>/</literal>, because
6805 the pattern contains a forward slash, which would otherwise have to be escaped
6806 by a backslash (<literal>\</literal>).
6810 Now, let's examine the pattern: it starts with the text <literal><script.*</literal>
6811 enclosed in parentheses. Since the dot matches any character, and <literal>*</literal>
6812 means: <quote>Match an arbitrary number of the element left of myself</quote>, this
6813 matches <quote><script</quote>, followed by <emphasis>any</emphasis> text, i.e.
6814 it matches the whole page, from the start of the first <script> tag.
6818 That's more than we want, but the pattern continues: <literal>document\.referrer</literal>
6819 matches only the exact string <quote>document.referrer</quote>. The dot needed to
6820 be <emphasis>escaped</emphasis>, i.e. preceded by a backslash, to take away its
6821 special meaning as a joker, and make it just a regular dot. So far, the meaning is:
6822 Match from the start of the first <script> tag in a the page, up to, and including,
6823 the text <quote>document.referrer</quote>, if <emphasis>both</emphasis> are present
6824 in the page (and appear in that order).
6828 But there's still more pattern to go. The next element, again enclosed in parentheses,
6829 is <literal>.*</script></literal>. You already know what <literal>.*</literal>
6830 means, so the whole pattern translates to: Match from the start of the first <script>
6831 tag in a page to the end of the last <script> tag, provided that the text
6832 <quote>document.referrer</quote> appears somewhere in between.
6836 This is still not the whole story, since we have ignored the options and the parentheses:
6837 The portions of the page matched by sub-patterns that are enclosed in parentheses, will be
6838 remembered and be available through the variables <literal>$1, $2, ...</literal> in
6839 the substitute. The <literal>U</literal> option switches to ungreedy matching, which means
6840 that the first <literal>.*</literal> in the pattern will only <quote>eat up</quote> all
6841 text in between <quote><script</quote> and the <emphasis>first</emphasis> occurrence
6842 of <quote>document.referrer</quote>, and that the second <literal>.*</literal> will
6843 only span the text up to the <emphasis>first</emphasis> <quote></script></quote>
6844 tag. Furthermore, the <literal>s</literal> option says that the match may span
6845 multiple lines in the page, and the <literal>g</literal> option again means that the
6846 substitution is global.
6850 So, to summarize, the pattern means: Match all scripts that contain the text
6851 <quote>document.referrer</quote>. Remember the parts of the script from
6852 (and including) the start tag up to (and excluding) the string
6853 <quote>document.referrer</quote> as <literal>$1</literal>, and the part following
6854 that string, up to and including the closing tag, as <literal>$2</literal>.
6858 Now the pattern is deciphered, but wasn't this about substituting things? So
6859 lets look at the substitute: <literal>$1"Not Your Business!"$2</literal> is
6860 easy to read: The text remembered as <literal>$1</literal>, followed by
6861 <literal>"Not Your Business!"</literal> (<emphasis>including</emphasis>
6862 the quotation marks!), followed by the text remembered as <literal>$2</literal>.
6863 This produces an exact copy of the original string, with the middle part
6864 (the <quote>document.referrer</quote>) replaced by <literal>"Not Your
6865 Business!"</literal>.
6869 The whole job now reads: Replace <quote>document.referrer</quote> by
6870 <literal>"Not Your Business!"</literal> wherever it appears inside a
6871 <script> tag. Note that this job won't break JavaScript syntax,
6872 since both the original and the replacement are syntactically valid
6873 string objects. The script just won't have access to the referrer
6874 information anymore.
6878 We'll show you two other jobs from the JavaScript taming department, but
6879 this time only point out the constructs of special interest:
6884 # The status bar is for displaying link targets, not pointless blahblah
6886 s/window\.status\s*=\s*(['"]).*?\1/dUmMy=1/ig</screen>
6890 <literal>\s</literal> stands for whitespace characters (space, tab, newline,
6891 carriage return, form feed), so that <literal>\s*</literal> means: <quote>zero
6892 or more whitespace</quote>. The <literal>?</literal> in <literal>.*?</literal>
6893 makes this matching of arbitrary text ungreedy. (Note that the <literal>U</literal>
6894 option is not set). The <literal>['"]</literal> construct means: <quote>a single
6895 <emphasis>or</emphasis> a double quote</quote>. Finally, <literal>\1</literal> is
6896 a back-reference to the first parenthesis just like <literal>$1</literal> above,
6897 with the difference that in the <emphasis>pattern</emphasis>, a backslash indicates
6898 a back-reference, whereas in the <emphasis>substitute</emphasis>, it's the dollar.
6902 So what does this job do? It replaces assignments of single- or double-quoted
6903 strings to the <quote>window.status</quote> object with a dummy assignment
6904 (using a variable name that is hopefully odd enough not to conflict with
6905 real variables in scripts). Thus, it catches many cases where e.g. pointless
6906 descriptions are displayed in the status bar instead of the link target when
6907 you move your mouse over links.
6912 # Kill OnUnload popups. Yummy. Test: http://www.zdnet.com/zdsubs/yahoo/tree/yfs.html
6914 s/(<body [^>]*)onunload(.*>)/$1never$2/iU</screen>
6919 <ulink url="http://www.w3.org/TR/2000/REC-DOM-Level-2-Events-20001113/events.html#Events-eventgroupings-htmlevents">OnUnload
6920 event binding</ulink> in the HTML DOM was a <emphasis>CRIME</emphasis>.
6921 When I close a browser window, I want it to close and die. Basta.
6922 This job replaces the <quote>onunload</quote> attribute in
6923 <quote><body></quote> tags with the dummy word <literal>never</literal>.
6924 Note that the <literal>i</literal> option makes the pattern matching
6925 case-insensitive. Also note that ungreedy matching alone doesn't always guarantee
6926 a minimal match: In the first parenthesis, we had to use <literal>[^>]*</literal>
6927 instead of <literal>.*</literal> to prevent the match from exceeding the
6928 <body> tag if it doesn't contain <quote>OnUnload</quote>, but the page's
6933 The last example is from the fun department:
6938 FILTER: fun Fun text replacements
6940 # Spice the daily news:
6942 s/microsoft(?!\.com)/MicroSuck/ig</screen>
6946 Note the <literal>(?!\.com)</literal> part (a so-called negative lookahead)
6947 in the job's pattern, which means: Don't match, if the string
6948 <quote>.com</quote> appears directly following <quote>microsoft</quote>
6949 in the page. This prevents links to microsoft.com from being trashed, while
6950 still replacing the word everywhere else.
6955 # Buzzword Bingo (example for extended regex syntax)
6957 s* industry[ -]leading \
6959 | customer[ -]focused \
6960 | market[ -]driven \
6961 | award[ -]winning # Comments are OK, too! \
6962 | high[ -]performance \
6963 | solutions[ -]based \
6967 *<font color="red"><b>BINGO!</b></font> \
6972 The <literal>x</literal> option in this job turns on extended syntax, and allows for
6973 e.g. the liberal use of (non-interpreted!) whitespace for nicer formatting.
6981 <!-- ~~~~~~~~ New section Header ~~~~~~~~~ -->
6983 <sect2 id="predefined-filters"><title>The Pre-defined Filters</title>
6987 Note each filter is also listed in the +filter action section above. Please
6988 keep these listings in sync.
6993 The distribution <filename>default.filter</filename> file contains a selection of
6994 pre-defined filters for your convenience:
6999 <term><emphasis>js-annoyances</emphasis></term>
7002 The purpose of this filter is to get rid of particularly annoying JavaScript abuse.
7007 replaces JavaScript references to the browser's referrer information
7008 with the string "Not Your Business!". This compliments the <literal><link
7009 linkend="hide-referrer">hide-referrer</link></literal> action on the content level.
7014 removes the bindings to the DOM's
7015 <ulink url="http://www.w3.org/TR/2000/REC-DOM-Level-2-Events-20001113/events.html#Events-eventgroupings-htmlevents">unload
7016 event</ulink> which we feel has no right to exist and is responsible for most <quote>exit consoles</quote>, i.e.
7017 nasty windows that pop up when you close another one.
7022 removes code that causes new windows to be opened with undesired properties, such as being
7023 full-screen, non-resizeable, without location, status or menu bar etc.
7029 Use with caution. This is an aggressive filter, and can break sites that
7030 rely heavily on JavaScript.
7036 <term><emphasis>js-events</emphasis></term>
7039 This is a very radical measure. It removes virtually all JavaScript event bindings, which
7040 means that scripts can not react to user actions such as mouse movements or clicks, window
7041 resizing etc, anymore. Use with caution!
7044 We <emphasis>strongly discourage</emphasis> using this filter as a default since it breaks
7045 many legitimate scripts. It is meant for use only on extra-nasty sites (should you really
7052 <term><emphasis>html-annoyances</emphasis></term>
7055 This filter will undo many common instances of HTML based abuse.
7058 The <literal>BLINK</literal> and <literal>MARQUEE</literal> tags
7059 are neutralized (yeah baby!), and browser windows will be created as
7060 resizeable (as of course they should be!), and will have location,
7061 scroll and menu bars -- even if specified otherwise.
7067 <term><emphasis>content-cookies</emphasis></term>
7070 Most cookies are set in the HTTP dialog, where they can be intercepted
7072 <literal><link linkend="crunch-incoming-cookies">crunch-incoming-cookies</link></literal>
7073 and <literal><link linkend="crunch-outgoing-cookies">crunch-outgoing-cookies</link></literal>
7074 actions. But web sites increasingly make use of HTML meta tags and JavaScript
7075 to sneak cookies to the browser on the content level.
7078 This filter disables most HTML and JavaScript code that reads or sets
7079 cookies. It cannot detect all clever uses of these types of code, so it
7080 should not be relied on as an absolute fix. Use it wherever you would also
7081 use the cookie crunch actions.
7087 <term><emphasis>refresh-tags</emphasis></term>
7090 Disable any refresh tags if the interval is greater than nine seconds (so
7091 that redirections done via refresh tags are not destroyed). This is useful
7092 for dial-on-demand setups, or for those who find this HTML feature
7099 <term><emphasis>unsolicited-popups</emphasis></term>
7102 This filter attempts to prevent only <quote>unsolicited</quote> pop-up
7103 windows from opening, yet still allow pop-up windows that the user
7104 has explicitly chosen to open. It was added in version 3.0.1,
7105 as an improvement over earlier such filters.
7108 Technical note: The filter works by redefining the window.open JavaScript
7109 function to a dummy function, <literal>PrivoxyWindowOpen()</literal>,
7110 during the loading and rendering phase of each HTML page access, and
7111 restoring the function afterward.
7114 This is recommended only for browsers that cannot perform this function
7115 reliably themselves. And be aware that some sites require such windows
7116 in order to function normally. Use with caution.
7122 <term><emphasis>all-popups</emphasis></term>
7125 Attempt to prevent <emphasis>all</emphasis> pop-up windows from opening.
7126 Note this should be used with even more discretion than the above, since
7127 it is more likely to break some sites that require pop-ups for normal
7128 usage. Use with caution.
7134 <term><emphasis>img-reorder</emphasis></term>
7137 This is a helper filter that has no value if used alone. It makes the
7138 <literal>banners-by-size</literal> and <literal>banners-by-link</literal>
7139 (see below) filters more effective and should be enabled together with them.
7145 <term><emphasis>banners-by-size</emphasis></term>
7148 This filter removes image tags purely based on what size they are. Fortunately
7149 for us, many ads and banner images tend to conform to certain standardized
7150 sizes, which makes this filter quite effective for ad stripping purposes.
7153 Occasionally this filter will cause false positives on images that are not ads,
7154 but just happen to be of one of the standard banner sizes.
7157 Recommended only for those who require extreme ad blocking. The default
7158 block rules should catch 95+% of all ads <emphasis>without</emphasis> this filter enabled.
7164 <term><emphasis>banners-by-link</emphasis></term>
7167 This is an experimental filter that attempts to kill any banners if
7168 their URLs seem to point to known or suspected click trackers. It is currently
7169 not of much value and is not recommended for use by default.
7175 <term><emphasis>webbugs</emphasis></term>
7178 Webbugs are small, invisible images (technically 1X1 GIF images), that
7179 are used to track users across websites, and collect information on them.
7180 As an HTML page is loaded by the browser, an embedded image tag causes the
7181 browser to contact a third-party site, disclosing the tracking information
7182 through the requested URL and/or cookies for that third-party domain, without
7183 the user ever becoming aware of the interaction with the third-party site.
7184 HTML-ized spam also uses a similar technique to verify email addresses.
7187 This filter removes the HTML code that loads such <quote>webbugs</quote>.
7193 <term><emphasis>tiny-textforms</emphasis></term>
7196 A rather special-purpose filter that can be used to enlarge textareas (those
7197 multi-line text boxes in web forms) and turn off hard word wrap in them.
7198 It was written for the sourceforge.net tracker system where such boxes are
7199 a nuisance, but it can be handy on other sites, too.
7202 It is not recommended to use this filter as a default.
7208 <term><emphasis>jumping-windows</emphasis></term>
7211 Many consider windows that move, or resize themselves to be abusive. This filter
7212 neutralizes the related JavaScript code. Note that some sites might not display
7213 or behave as intended when using this filter. Use with caution.
7219 <term><emphasis>frameset-borders</emphasis></term>
7222 Some web designers seem to assume that everyone in the world will view their
7223 web sites using the same browser brand and version, screen resolution etc,
7224 because only that assumption could explain why they'd use static frame sizes,
7225 yet prevent their frames from being resized by the user, should they be too
7226 small to show their whole content.
7229 This filter removes the related HTML code. It should only be applied to sites
7236 <term><emphasis>demoronizer</emphasis></term>
7239 Many Microsoft products that generate HTML use non-standard extensions (read:
7240 violations) of the ISO 8859-1 aka Latin-1 character set. This can cause those
7241 HTML documents to display with errors on standard-compliant platforms.
7244 This filter translates the MS-only characters into Latin-1 equivalents.
7245 It is not necessary when using MS products, and will cause corruption of
7246 all documents that use 8-bit character sets other than Latin-1. It's mostly
7247 worthwhile for Europeans on non-MS platforms, if weird garbage characters
7248 sometimes appear on some pages, or user agents that don't correct for this on
7251 My version of Mozilla (ancient) shows litte square boxes for quote
7252 characters, and apostrophes on moronized pages. So many pages have this, I
7253 can read them fine now. HB 08/27/06
7260 <term><emphasis>shockwave-flash</emphasis></term>
7263 A filter for shockwave haters. As the name suggests, this filter strips code
7264 out of web pages that is used to embed shockwave flash objects.
7272 <term><emphasis>quicktime-kioskmode</emphasis></term>
7275 Change HTML code that embeds Quicktime objects so that kioskmode, which
7276 prevents saving, is disabled.
7282 <term><emphasis>fun</emphasis></term>
7285 Text replacements for subversive browsing fun. Make fun of your favorite
7286 Monopolist or play buzzword bingo.
7292 <term><emphasis>crude-parental</emphasis></term>
7295 A demonstration-only filter that shows how <application>Privoxy</application>
7296 can be used to delete web content on a keyword basis.
7302 <term><emphasis>ie-exploits</emphasis></term>
7305 An experimental collection of text replacements to disable malicious HTML and JavaScript
7306 code that exploits known security holes in Internet Explorer.
7309 Presently, it only protects against Nimda and a cross-site scripting bug, and
7310 would need active maintenance to provide more substantial protection.
7316 <term><emphasis>site-specifics</emphasis></term>
7319 Some web sites have very specific problems, the cure for which doesn't apply
7320 anywhere else, or could even cause damage on other sites.
7323 This is a collection of such site-specific cures which should only be applied
7324 to the sites they were intended for, which is what the supplied
7325 <filename>default.action</filename> file does. Users shouldn't need to change
7326 anything regarding this filter.
7332 <term><emphasis>google</emphasis></term>
7335 A CSS based block for Google text ads. Also removes a width limitation
7336 and the toolbar advertisement.
7342 <term><emphasis>yahoo</emphasis></term>
7345 Another CSS based block, this time for Yahoo text ads. And removes
7346 a width limitation as well.
7352 <term><emphasis>msn</emphasis></term>
7355 Another CSS based block, this time for MSN text ads. And removes
7356 tracking URLs, as well as a width limitation.
7362 <term><emphasis>blogspot</emphasis></term>
7365 Cleans up some Blogspot blogs. Read the fine print before using this one!
7368 This filter also intentionally removes some navigation stuff and sets the
7369 page width to 100%. As a result, some rounded <quote>corners</quote> would
7370 appear to early or not at all and as fixing this would require a browser
7371 that understands background-size (CSS3), they are removed instead.
7377 <term><emphasis>xml-to-html</emphasis></term>
7380 Server-header filter to change the Content-Type from xml to html.
7386 <term><emphasis>html-to-xml</emphasis></term>
7389 Server-header filter to change the Content-Type from html to xml.
7395 <term><emphasis>no-ping</emphasis></term>
7398 Removes the non-standard <literal>ping</literal> attribute from
7399 anchor and area HTML tags.
7405 <term><emphasis>hide-tor-exit-notation</emphasis></term>
7408 Client-header filter to remove the <command>Tor</command> exit node notation
7409 found in Host and Referer headers.
7412 If &my-app; and <command>Tor</command> are chained and &my-app;
7413 is configured to use socks4a, one can use <quote>http://www.example.org.foobar.exit/</quote>
7414 to access the host <quote>www.example.org</quote> through the
7415 <command>Tor</command> exit node <quote>foobar</quote>.
7418 As the HTTP client isn't aware of this notation, it treats the
7419 whole string <quote>www.example.org.foobar.exit</quote> as host and uses it
7420 for the <quote>Host</quote> and <quote>Referer</quote> headers. From the
7421 server's point of view the resulting headers are invalid and can cause problems.
7424 An invalid <quote>Referer</quote> header can trigger <quote>hot-linking</quote>
7425 protections, an invalid <quote>Host</quote> header will make it impossible for
7426 the server to find the right vhost (several domains hosted on the same IP address).
7429 This client-header filter removes the <quote>foo.exit</quote> part in those headers
7430 to prevent the mentioned problems. Note that it only modifies
7431 the HTTP headers, it doesn't make it impossible for the server
7432 to detect your <command>Tor</command> exit node based on the IP address
7433 the request is coming from.
7440 <term><emphasis> </emphasis></term>
7453 <!-- ~~~~~~~~ New section Header ~~~~~~~~~ -->
7454 <sect2 id="external-filter-syntax"><title>External filter syntax</title>
7456 External filters are scripts or programs that can modify the content in
7457 case common <literal><link linkend="filter">filters</link></literal>
7458 aren't powerful enough.
7461 External filters can be written in any language the platform &my-app; runs
7465 They are controlled with the
7466 <literal><link linkend="external-filter">external-filter</link></literal> action
7467 and have to be defined in the <literal><link linkend="filterfile">filterfile</link></literal>
7471 The header looks like any other filter, but instead of pcrs jobs, external
7472 filters contain a single job which can be a program or a shell script (which
7473 may call other scripts or programs).
7476 External filters read the content from STDIN and write the rewritten
7477 content to STDOUT. The environment variables PRIVOXY_URL, PRIVOXY_PATH,
7478 PRIVOXY_HOST, PRIVOXY_ORIGIN can be used to get some details about the
7482 &my-app; will temporary store the content to filter in the
7483 <literal><link linkend="temporary-directory">temporary-directory</link></literal>.
7487 EXTERNAL-FILTER: cat Pointless example filter that doesn't actually modify the content
7490 # Incorrect reimplementation of the filter above in POSIX shell.
7492 # Note that it's a single job that spans multiple lines, the line
7493 # breaks are not passed to the shell, thus the semicolons are required.
7495 # If the script isn't trivial, it is recommended to put it into an external file.
7497 # In general, writing external filters entirely in POSIX shell is not
7498 # considered a good idea.
7499 EXTERNAL-FILTER: cat2 Pointless example filter that despite its name may actually modify the content
7505 EXTERNAL-FILTER: rotate-image Rotate an image by 180 degree. Test filter with limited value.
7506 /usr/local/bin/convert - -rotate 180 -
7508 EXTERNAL-FILTER: citation-needed Adds a "[citation needed]" tag to an image. The coordinates may need adjustment.
7509 /usr/local/bin/convert - -pointsize 16 -fill white -annotate +17+418 "[citation needed]" -
7515 Currently external filters are executed with &my-app;'s privileges!
7516 Only use external filters you understand and trust.
7520 External filters are experimental and the syntax may change in the future.
7526 <!-- ~ End section ~ -->
7530 <!-- ~~~~~ New section ~~~~~ -->
7532 <sect1 id="templates">
7533 <title>Privoxy's Template Files</title>
7535 All <application>Privoxy</application> built-in pages, i.e. error pages such as the
7536 <ulink url="http://show-the-404-error.page"><quote>404 - No Such Domain</quote>
7537 error page</ulink>, the <ulink
7538 url="http://ads.bannerserver.example.com/nasty-ads/sponsor.html"><quote>BLOCKED</quote>
7540 and all pages of its <ulink url="http://config.privoxy.org/">web-based
7541 user interface</ulink>, are generated from <emphasis>templates</emphasis>.
7542 (<application>Privoxy</application> must be running for the above links to work as
7547 These templates are stored in a subdirectory of the <link linkend="confdir">configuration
7548 directory</link> called <filename>templates</filename>. On Unixish platforms,
7550 <ulink url="file:///etc/privoxy/templates/"><filename>/etc/privoxy/templates/</filename></ulink>.
7554 The templates are basically normal HTML files, but with place-holders (called symbols
7555 or exports), which <application>Privoxy</application> fills at run time. It
7556 is possible to edit the templates with a normal text editor, should you want
7557 to customize them. (<emphasis>Not recommended for the casual
7558 user</emphasis>). Should you create your own custom templates, you should use
7559 the <filename>config</filename> setting <link linkend="templdir">templdir</link>
7560 to specify an alternate location, so your templates do not get overwritten
7564 Note that just like in configuration files, lines starting
7565 with <literal>#</literal> are ignored when the templates are filled in.
7569 The place-holders are of the form <literal>@name@</literal>, and you will
7570 find a list of available symbols, which vary from template to template,
7571 in the comments at the start of each file. Note that these comments are not
7572 always accurate, and that it's probably best to look at the existing HTML
7573 code to find out which symbols are supported and what they are filled in with.
7577 A special application of this substitution mechanism is to make whole
7578 blocks of HTML code disappear when a specific symbol is set. We use this
7579 for many purposes, one of them being to include the beta warning in all
7580 our user interface (CGI) pages when <application>Privoxy</application>
7581 is in an alpha or beta development stage:
7586 <!-- @if-unstable-start -->
7588 ... beta warning HTML code goes here ...
7590 <!-- if-unstable-end@ --></screen>
7594 If the "unstable" symbol is set, everything in between and including
7595 <literal>@if-unstable-start</literal> and <literal>if-unstable-end@</literal>
7596 will disappear, leaving nothing but an empty comment:
7600 <screen><!-- --></screen>
7604 There's also an if-then-else construct and an <literal>#include</literal>
7605 mechanism, but you'll sure find out if you are inclined to edit the
7610 All templates refer to a style located at
7611 <ulink url="http://config.privoxy.org/send-stylesheet"><literal>http://config.privoxy.org/send-stylesheet</literal></ulink>.
7612 This is, of course, locally served by <application>Privoxy</application>
7613 and the source for it can be found and edited in the
7614 <filename>cgi-style.css</filename> template.
7619 <!-- ~ End section ~ -->
7623 <!-- ~~~~~ New section ~~~~~ -->
7625 <sect1 id="contact"><title>Contacting the Developers, Bug Reporting and Feature
7628 <!-- Include contacting.sgml boilerplate: -->
7630 <!-- end boilerplate -->
7634 <!-- ~ End section ~ -->
7637 <!-- ~~~~~ New section ~~~~~ -->
7638 <sect1 id="copyright"><title>Privoxy Copyright, License and History</title>
7640 <!-- Include copyright.sgml: -->
7642 <!-- end copyright -->
7645 <application>Privoxy</application> is free software; you can
7646 redistribute it and/or modify it under the terms of the
7647 <citetitle>GNU General Public License</citetitle>, version 2,
7648 as published by the Free Software Foundation and included in
7652 <!-- ~~~~~ New section ~~~~~ -->
7653 <sect2 id="license"><title>License</title>
7655 <screen><![ RCDATA [ &GPLv2; ]]></screen>
7659 <!-- ~ End section ~ -->
7662 <!-- ~~~~~ New section ~~~~~ -->
7664 <sect2 id="history"><title>History</title>
7665 <!-- Include history.sgml: -->
7667 <!-- end history -->
7670 <sect2 id="authors"><title>Authors</title>
7671 <!-- Include p-authors.sgml: -->
7673 <!-- end authors -->
7678 <!-- ~ End section ~ -->
7681 <!-- ~~~~~ New section ~~~~~ -->
7682 <sect1 id="seealso"><title>See Also</title>
7683 <!-- Include seealso.sgml: -->
7685 <!-- end seealso -->
7690 <!-- ~~~~~ New section ~~~~~ -->
7691 <sect1 id="appendix"><title>Appendix</title>
7694 <!-- ~~~~~ New section ~~~~~ -->
7696 <title>Regular Expressions</title>
7698 <application>Privoxy</application> uses Perl-style <quote>regular
7699 expressions</quote> in its <link linkend="actions-file">actions
7700 files</link> and <link linkend="filter-file">filter file</link>,
7701 through the <ulink url="http://www.pcre.org/">PCRE</ulink> and
7704 <ulink url="http://www.oesterhelt.org/pcrs/">PCRS</ulink> libraries.
7706 <application>PCRS</application> libraries.
7710 If you are reading this, you probably don't understand what <quote>regular
7711 expressions</quote> are, or what they can do. So this will be a very brief
7712 introduction only. A full explanation would require a <ulink
7713 url="http://www.oreilly.com/catalog/regex/">book</ulink> ;-)
7717 Regular expressions provide a language to describe patterns that can be
7718 run against strings of characters (letter, numbers, etc), to see if they
7719 match the string or not. The patterns are themselves (sometimes complex)
7720 strings of literal characters, combined with wild-cards, and other special
7721 characters, called meta-characters. The <quote>meta-characters</quote> have
7722 special meanings and are used to build complex patterns to be matched against.
7723 Perl Compatible Regular Expressions are an especially convenient
7724 <quote>dialect</quote> of the regular expression language.
7728 To make a simple analogy, we do something similar when we use wild-card
7729 characters when listing files with the <command>dir</command> command in DOS.
7730 <literal>*.*</literal> matches all filenames. The <quote>special</quote>
7731 character here is the asterisk which matches any and all characters. We can be
7732 more specific and use <literal>?</literal> to match just individual
7733 characters. So <quote>dir file?.text</quote> would match
7734 <quote>file1.txt</quote>, <quote>file2.txt</quote>, etc. We are pattern
7735 matching, using a similar technique to <quote>regular expressions</quote>!
7739 Regular expressions do essentially the same thing, but are much, much more
7740 powerful. There are many more <quote>special characters</quote> and ways of
7741 building complex patterns however. Let's look at a few of the common ones,
7742 and then some examples:
7747 <emphasis>.</emphasis> - Matches any single character, e.g. <quote>a</quote>,
7748 <quote>A</quote>, <quote>4</quote>, <quote>:</quote>, or <quote>@</quote>.
7750 </simplelist></para>
7754 <emphasis>?</emphasis> - The preceding character or expression is matched ZERO or ONE
7757 </simplelist></para>
7761 <emphasis>+</emphasis> - The preceding character or expression is matched ONE or MORE
7764 </simplelist></para>
7768 <emphasis>*</emphasis> - The preceding character or expression is matched ZERO or MORE
7771 </simplelist></para>
7775 <emphasis>\</emphasis> - The <quote>escape</quote> character denotes that
7776 the following character should be taken literally. This is used where one of the
7777 special characters (e.g. <quote>.</quote>) needs to be taken literally and
7778 not as a special meta-character. Example: <quote>example\.com</quote>, makes
7779 sure the period is recognized only as a period (and not expanded to its
7780 meta-character meaning of any single character).
7782 </simplelist></para>
7786 <emphasis>[ ]</emphasis> - Characters enclosed in brackets will be matched if
7787 any of the enclosed characters are encountered. For instance, <quote>[0-9]</quote>
7788 matches any numeric digit (zero through nine). As an example, we can combine
7789 this with <quote>+</quote> to match any digit one of more times: <quote>[0-9]+</quote>.
7791 </simplelist></para>
7795 <emphasis>( )</emphasis> - parentheses are used to group a sub-expression,
7796 or multiple sub-expressions.
7798 </simplelist></para>
7802 <emphasis>|</emphasis> - The <quote>bar</quote> character works like an
7803 <quote>or</quote> conditional statement. A match is successful if the
7804 sub-expression on either side of <quote>|</quote> matches. As an example:
7805 <quote>/(this|that) example/</quote> uses grouping and the bar character
7806 and would match either <quote>this example</quote> or <quote>that
7807 example</quote>, and nothing else.
7809 </simplelist></para>
7812 These are just some of the ones you are likely to use when matching URLs with
7813 <application>Privoxy</application>, and is a long way from a definitive
7814 list. This is enough to get us started with a few simple examples which may
7815 be more illuminating:
7819 <emphasis><literal>/.*/banners/.*</literal></emphasis> - A simple example
7820 that uses the common combination of <quote>.</quote> and <quote>*</quote> to
7821 denote any character, zero or more times. In other words, any string at all.
7822 So we start with a literal forward slash, then our regular expression pattern
7823 (<quote>.*</quote>) another literal forward slash, the string
7824 <quote>banners</quote>, another forward slash, and lastly another
7825 <quote>.*</quote>. We are building
7826 a directory path here. This will match any file with the path that has a
7827 directory named <quote>banners</quote> in it. The <quote>.*</quote> matches
7828 any characters, and this could conceivably be more forward slashes, so it
7829 might expand into a much longer looking path. For example, this could match:
7830 <quote>/eye/hate/spammers/banners/annoy_me_please.gif</quote>, or just
7831 <quote>/banners/annoying.html</quote>, or almost an infinite number of other
7832 possible combinations, just so it has <quote>banners</quote> in the path
7837 And now something a little more complex:
7841 <emphasis><literal>/.*/adv((er)?ts?|ertis(ing|ements?))?/</literal></emphasis> -
7842 We have several literal forward slashes again (<quote>/</quote>), so we are
7843 building another expression that is a file path statement. We have another
7844 <quote>.*</quote>, so we are matching against any conceivable sub-path, just so
7845 it matches our expression. The only true literal that <emphasis>must
7846 match</emphasis> our pattern is <application>adv</application>, together with
7847 the forward slashes. What comes after the <quote>adv</quote> string is the
7852 Remember the <quote>?</quote> means the preceding expression (either a
7853 literal character or anything grouped with <quote>(...)</quote> in this case)
7854 can exist or not, since this means either zero or one match. So
7855 <quote>((er)?ts?|ertis(ing|ements?))</quote> is optional, as are the
7856 individual sub-expressions: <quote>(er)</quote>,
7857 <quote>(ing|ements?)</quote>, and the <quote>s</quote>. The <quote>|</quote>
7858 means <quote>or</quote>. We have two of those. For instance,
7859 <quote>(ing|ements?)</quote>, can expand to match either <quote>ing</quote>
7860 <emphasis>OR</emphasis> <quote>ements?</quote>. What is being done here, is an
7861 attempt at matching as many variations of <quote>advertisement</quote>, and
7862 similar, as possible. So this would expand to match just <quote>adv</quote>,
7863 or <quote>advert</quote>, or <quote>adverts</quote>, or
7864 <quote>advertising</quote>, or <quote>advertisement</quote>, or
7865 <quote>advertisements</quote>. You get the idea. But it would not match
7866 <quote>advertizements</quote> (with a <quote>z</quote>). We could fix that by
7867 changing our regular expression to:
7868 <quote>/.*/adv((er)?ts?|erti(s|z)(ing|ements?))?/</quote>, which would then match
7873 <emphasis><literal>/.*/advert[0-9]+\.(gif|jpe?g)</literal></emphasis> - Again
7874 another path statement with forward slashes. Anything in the square brackets
7875 <quote>[ ]</quote> can be matched. This is using <quote>0-9</quote> as a
7876 shorthand expression to mean any digit one through nine. It is the same as
7877 saying <quote>0123456789</quote>. So any digit matches. The <quote>+</quote>
7878 means one or more of the preceding expression must be included. The preceding
7879 expression here is what is in the square brackets -- in this case, any digit
7880 one through nine. Then, at the end, we have a grouping: <quote>(gif|jpe?g)</quote>.
7881 This includes a <quote>|</quote>, so this needs to match the expression on
7882 either side of that bar character also. A simple <quote>gif</quote> on one side, and the other
7883 side will in turn match either <quote>jpeg</quote> or <quote>jpg</quote>,
7884 since the <quote>?</quote> means the letter <quote>e</quote> is optional and
7885 can be matched once or not at all. So we are building an expression here to
7886 match image GIF or JPEG type image file. It must include the literal
7887 string <quote>advert</quote>, then one or more digits, and a <quote>.</quote>
7888 (which is now a literal, and not a special character, since it is escaped
7889 with <quote>\</quote>), and lastly either <quote>gif</quote>, or
7890 <quote>jpeg</quote>, or <quote>jpg</quote>. Some possible matches would
7891 include: <quote>//advert1.jpg</quote>,
7892 <quote>/nasty/ads/advert1234.gif</quote>,
7893 <quote>/banners/from/hell/advert99.jpg</quote>. It would not match
7894 <quote>advert1.gif</quote> (no leading slash), or
7895 <quote>/adverts232.jpg</quote> (the expression does not include an
7896 <quote>s</quote>), or <quote>/advert1.jsp</quote> (<quote>jsp</quote> is not
7897 in the expression anywhere).
7901 We are barely scratching the surface of regular expressions here so that you
7902 can understand the default <application>Privoxy</application>
7903 configuration files, and maybe use this knowledge to customize your own
7904 installation. There is much, much more that can be done with regular
7905 expressions. Now that you know enough to get started, you can learn more on
7910 More reading on Perl Compatible Regular expressions:
7911 <ulink url="http://perldoc.perl.org/perlre.html">http://perldoc.perl.org/perlre.html</ulink>
7915 For information on regular expression based substitutions and their applications
7916 in filters, please see the <link linkend="filter-file">filter file tutorial</link>
7921 <!-- ~ End section ~ -->
7924 <!-- ~~~~~ New section ~~~~~ -->
7926 <title>Privoxy's Internal Pages</title>
7929 Since <application>Privoxy</application> proxies each requested
7930 web page, it is easy for <application>Privoxy</application> to
7931 trap certain special URLs. In this way, we can talk directly to
7932 <application>Privoxy</application>, and see how it is
7933 configured, see how our rules are being applied, change these
7934 rules and other configuration options, and even turn
7935 <application>Privoxy's</application> filtering off, all with
7941 The URLs listed below are the special ones that allow direct access
7942 to <application>Privoxy</application>. Of course,
7943 <application>Privoxy</application> must be running to access these. If
7944 not, you will get a friendly error message. Internet access is not
7957 <ulink url="http://config.privoxy.org/">http://config.privoxy.org/</ulink>
7961 There is a shortcut: <ulink url="http://p.p/">http://p.p/</ulink> (But it
7962 doesn't provide a fall-back to a real page, in case the request is not
7963 sent through <application>Privoxy</application>)
7969 Show information about the current configuration, including viewing and
7970 editing of actions files:
7974 <ulink url="http://config.privoxy.org/show-status">http://config.privoxy.org/show-status</ulink>
7981 Show the source code version numbers:
7985 <ulink url="http://config.privoxy.org/show-version">http://config.privoxy.org/show-version</ulink>
7992 Show the browser's request headers:
7996 <ulink url="http://config.privoxy.org/show-request">http://config.privoxy.org/show-request</ulink>
8003 Show which actions apply to a URL and why:
8007 <ulink url="http://config.privoxy.org/show-url-info">http://config.privoxy.org/show-url-info</ulink>
8014 Toggle Privoxy on or off. This feature can be turned off/on in the main
8015 <filename>config</filename> file. When toggled <quote>off</quote>, <quote>Privoxy</quote>
8016 continues to run, but only as a pass-through proxy, with no actions taking
8021 <ulink url="http://config.privoxy.org/toggle">http://config.privoxy.org/toggle</ulink>
8025 Short cuts. Turn off, then on:
8029 <ulink url="http://config.privoxy.org/toggle?set=disable">http://config.privoxy.org/toggle?set=disable</ulink>
8034 <ulink url="http://config.privoxy.org/toggle?set=enable">http://config.privoxy.org/toggle?set=enable</ulink>
8045 <!-- ~~~~~ New section ~~~~~ -->
8047 <title>Chain of Events</title>
8049 Let's take a quick look at how some of <application>Privoxy's</application>
8050 core features are triggered, and the ensuing sequence of events when a web
8051 page is requested by your browser:
8058 First, your web browser requests a web page. The browser knows to send
8059 the request to <application>Privoxy</application>, which will in turn,
8060 relay the request to the remote web server after passing the following
8066 <application>Privoxy</application> traps any request for its own internal CGI
8067 pages (e.g <ulink url="http://p.p/">http://p.p/</ulink>) and sends the CGI page back to the browser.
8072 Next, <application>Privoxy</application> checks to see if the URL
8074 linkend="BLOCK"><quote>+block</quote></link> patterns. If
8075 so, the URL is then blocked, and the remote web server will not be contacted.
8076 <link linkend="HANDLE-AS-IMAGE"><quote>+handle-as-image</quote></link>
8078 <link linkend="HANDLE-AS-EMPTY-DOCUMENT"><quote>+handle-as-empty-document</quote></link>
8079 are then checked, and if there is no match, an
8080 HTML <quote>BLOCKED</quote> page is sent back to the browser. Otherwise, if
8081 it does match, an image is returned for the former, and an empty text
8082 document for the latter. The type of image would depend on the setting of
8083 <link linkend="SET-IMAGE-BLOCKER"><quote>+set-image-blocker</quote></link>
8084 (blank, checkerboard pattern, or an HTTP redirect to an image elsewhere).
8089 Untrusted URLs are blocked. If URLs are being added to the
8090 <filename>trust</filename> file, then that is done.
8095 If the URL pattern matches the <link
8096 linkend="FAST-REDIRECTS"><quote>+fast-redirects</quote></link> action,
8097 it is then processed. Unwanted parts of the requested URL are stripped.
8102 Now the rest of the client browser's request headers are processed. If any
8103 of these match any of the relevant actions (e.g. <link
8104 linkend="HIDE-USER-AGENT"><quote>+hide-user-agent</quote></link>,
8105 etc.), headers are suppressed or forged as determined by these actions and
8111 Now the web server starts sending its response back (i.e. typically a web
8117 First, the server headers are read and processed to determine, among other
8118 things, the MIME type (document type) and encoding. The headers are then
8119 filtered as determined by the
8120 <link linkend="CRUNCH-INCOMING-COOKIES"><quote>+crunch-incoming-cookies</quote></link>,
8121 <link linkend="SESSION-COOKIES-ONLY"><quote>+session-cookies-only</quote></link>,
8122 and <link linkend="DOWNGRADE-HTTP-VERSION"><quote>+downgrade-http-version</quote></link>
8128 If any <link linkend="FILTER"><quote>+filter</quote></link> action
8130 linkend="DEANIMATE-GIFS"><quote>+deanimate-gifs</quote></link>
8131 action applies (and the document type fits the action), the rest of the page is
8132 read into memory (up to a configurable limit). Then the filter rules (from
8133 <filename>default.filter</filename> and any other filter files) are
8134 processed against the buffered content. Filters are applied in the order
8135 they are specified in one of the filter files. Animated GIFs, if present,
8136 are reduced to either the first or last frame, depending on the action
8137 setting.The entire page, which is now filtered, is then sent by
8138 <application>Privoxy</application> back to your browser.
8141 If neither a <link linkend="FILTER"><quote>+filter</quote></link> action
8143 linkend="DEANIMATE-GIFS"><quote>+deanimate-gifs</quote></link>
8144 matches, then <application>Privoxy</application> passes the raw data through
8145 to the client browser as it becomes available.
8150 As the browser receives the now (possibly filtered) page content, it
8151 reads and then requests any URLs that may be embedded within the page
8152 source, e.g. ad images, stylesheets, JavaScript, other HTML documents (e.g.
8153 frames), sounds, etc. For each of these objects, the browser issues a
8154 separate request (this is easily viewable in <application>Privoxy's</application>
8155 logs). And each such request is in turn processed just as above. Note that a
8156 complex web page will have many, many such embedded URLs. If these
8157 secondary requests are to a different server, then quite possibly a very
8158 differing set of actions is triggered.
8165 NOTE: This is somewhat of a simplistic overview of what happens with each URL
8166 request. For the sake of brevity and simplicity, we have focused on
8167 <application>Privoxy's</application> core features only.
8173 <!-- ~~~~~ New section ~~~~~ -->
8174 <sect2 id="actionsanat">
8175 <title>Troubleshooting: Anatomy of an Action</title>
8178 The way <application>Privoxy</application> applies
8179 <link linkend="ACTIONS">actions</link> and <link linkend="FILTER">filters</link>
8180 to any given URL can be complex, and not always so
8181 easy to understand what is happening. And sometimes we need to be able to
8182 <emphasis>see</emphasis> just what <application>Privoxy</application> is
8183 doing. Especially, if something <application>Privoxy</application> is doing
8184 is causing us a problem inadvertently. It can be a little daunting to look at
8185 the actions and filters files themselves, since they tend to be filled with
8186 <link linkend="regex">regular expressions</link> whose consequences are not
8191 One quick test to see if <application>Privoxy</application> is causing a problem
8192 or not, is to disable it temporarily. This should be the first troubleshooting
8193 step (be sure to flush caches afterward!). Looking at the
8194 logs is a good idea too. (Note that both the toggle feature and logging are
8195 enabled via <filename>config</filename> file settings, and may need to be
8196 turned <quote>on</quote>.)
8199 Another easy troubleshooting step to try is if you have done any
8200 customization of your installation, revert back to the installed
8201 defaults and see if that helps. There are times the developers get complaints
8202 about one thing or another, and the problem is more related to a customized
8203 configuration issue.
8207 <application>Privoxy</application> also provides the
8208 <ulink url="http://config.privoxy.org/show-url-info">http://config.privoxy.org/show-url-info</ulink>
8209 page that can show us very specifically how <application>actions</application>
8210 are being applied to any given URL. This is a big help for troubleshooting.
8214 First, enter one URL (or partial URL) at the prompt, and then
8215 <application>Privoxy</application> will tell us
8216 how the current configuration will handle it. This will not
8217 help with filtering effects (i.e. the <link
8218 linkend="FILTER"><quote>+filter</quote></link> action) from
8219 one of the filter files since this is handled very
8220 differently and not so easy to trap! It also will not tell you about any other
8221 URLs that may be embedded within the URL you are testing. For instance, images
8222 such as ads are expressed as URLs within the raw page source of HTML pages. So
8223 you will only get info for the actual URL that is pasted into the prompt area
8224 -- not any sub-URLs. If you want to know about embedded URLs like ads, you
8225 will have to dig those out of the HTML source. Use your browser's <quote>View
8226 Page Source</quote> option for this. Or right click on the ad, and grab the
8231 Let's try an example, <ulink url="http://google.com">google.com</ulink>,
8232 and look at it one section at a time in a sample configuration (your real
8233 configuration may vary):
8238 Matches for http://www.google.com:
8240 In file: default.action <guibutton>[ View ]</guibutton> <guibutton>[ Edit ]</guibutton>
8242 {+change-x-forwarded-for{block}
8243 +deanimate-gifs {last}
8244 +fast-redirects {check-decoded-url}
8245 +filter {refresh-tags}
8246 +filter {img-reorder}
8247 +filter {banners-by-size}
8249 +filter {jumping-windows}
8250 +filter {ie-exploits}
8251 +hide-from-header {block}
8252 +hide-referrer {forge}
8253 +session-cookies-only
8254 +set-image-blocker {pattern}
8257 { -session-cookies-only }
8263 In file: user.action <guibutton>[ View ]</guibutton> <guibutton>[ Edit ]</guibutton>
8264 (no matches in this file)
8269 This is telling us how we have defined our
8270 <link linkend="ACTIONS"><quote>actions</quote></link>, and
8271 which ones match for our test case, <quote>google.com</quote>.
8272 Displayed is all the actions that are available to us. Remember,
8273 the <literal>+</literal> sign denotes <quote>on</quote>. <literal>-</literal>
8274 denotes <quote>off</quote>. So some are <quote>on</quote> here, but many
8275 are <quote>off</quote>. Each example we try may provide a slightly different
8276 end result, depending on our configuration directives.
8280 is for our <filename>default.action</filename> file. The large, multi-line
8281 listing, is how the actions are set to match for all URLs, i.e. our default
8282 settings. If you look at your <quote>actions</quote> file, this would be the
8283 section just below the <quote>aliases</quote> section near the top. This
8284 will apply to all URLs as signified by the single forward slash at the end
8285 of the listing -- <quote> / </quote>.
8289 But we have defined additional actions that would be exceptions to these general
8290 rules, and then we list specific URLs (or patterns) that these exceptions
8291 would apply to. Last match wins. Just below this then are two explicit
8292 matches for <quote>.google.com</quote>. The first is negating our previous
8293 cookie setting, which was for <link
8294 linkend="SESSION-COOKIES-ONLY"><quote>+session-cookies-only</quote></link>
8295 (i.e. not persistent). So we will allow persistent cookies for google, at
8296 least that is how it is in this example. The second turns
8297 <emphasis>off</emphasis> any <link
8298 linkend="FAST-REDIRECTS"><quote>+fast-redirects</quote></link>
8299 action, allowing this to take place unmolested. Note that there is a leading
8300 dot here -- <quote>.google.com</quote>. This will match any hosts and
8301 sub-domains, in the google.com domain also, such as
8302 <quote>www.google.com</quote> or <quote>mail.google.com</quote>. But it would not
8303 match <quote>www.google.de</quote>! So, apparently, we have these two actions
8304 defined as exceptions to the general rules at the top somewhere in the lower
8305 part of our <filename>default.action</filename> file, and
8306 <quote>google.com</quote> is referenced somewhere in these latter sections.
8310 Then, for our <filename>user.action</filename> file, we again have no hits.
8311 So there is nothing google-specific that we might have added to our own, local
8312 configuration. If there was, those actions would over-rule any actions from
8313 previously processed files, such as <filename>default.action</filename>.
8314 <filename>user.action</filename> typically has the last word. This is the
8315 best place to put hard and fast exceptions,
8319 And finally we pull it all together in the bottom section and summarize how
8320 <application>Privoxy</application> is applying all its <quote>actions</quote>
8321 to <quote>google.com</quote>:
8332 +change-x-forwarded-for{block}
8333 -client-header-filter{hide-tor-exit-notation}
8334 -content-type-overwrite
8335 -crunch-client-header
8336 -crunch-if-none-match
8337 -crunch-incoming-cookies
8338 -crunch-outgoing-cookies
8339 -crunch-server-header
8340 +deanimate-gifs {last}
8341 -downgrade-http-version
8344 -filter {content-cookies}
8345 -filter {all-popups}
8346 -filter {banners-by-link}
8347 -filter {tiny-textforms}
8348 -filter {frameset-borders}
8349 -filter {demoronizer}
8350 -filter {shockwave-flash}
8351 -filter {quicktime-kioskmode}
8353 -filter {crude-parental}
8354 -filter {site-specifics}
8355 -filter {js-annoyances}
8356 -filter {html-annoyances}
8357 +filter {refresh-tags}
8358 -filter {unsolicited-popups}
8359 +filter {img-reorder}
8360 +filter {banners-by-size}
8362 +filter {jumping-windows}
8363 +filter {ie-exploits}
8370 -handle-as-empty-document
8372 -hide-accept-language
8373 -hide-content-disposition
8374 +hide-from-header {block}
8375 -hide-if-modified-since
8376 +hide-referrer {forge}
8379 -overwrite-last-modified
8380 -prevent-compression
8382 -server-header-filter{xml-to-html}
8383 -server-header-filter{html-to-xml}
8384 -session-cookies-only
8385 +set-image-blocker {pattern} </screen>
8389 Notice the only difference here to the previous listing, is to
8390 <quote>fast-redirects</quote> and <quote>session-cookies-only</quote>,
8391 which are activated specifically for this site in our configuration,
8392 and thus show in the <quote>Final Results</quote>.
8396 Now another example, <quote>ad.doubleclick.net</quote>:
8402 { +block{Domains starts with "ad"} }
8405 { +block{Domain contains "ad"} }
8408 { +block{Doubleclick banner server} +handle-as-image }
8409 .[a-vx-z]*.doubleclick.net
8414 We'll just show the interesting part here - the explicit matches. It is
8415 matched three different times. Two <quote>+block{}</quote> sections,
8416 and a <quote>+block{} +handle-as-image</quote>,
8417 which is the expanded form of one of our aliases that had been defined as:
8418 <quote>+block-as-image</quote>. (<link
8419 linkend="ALIASES"><quote>Aliases</quote></link> are defined in
8420 the first section of the actions file and typically used to combine more
8425 Any one of these would have done the trick and blocked this as an unwanted
8426 image. This is unnecessarily redundant since the last case effectively
8427 would also cover the first. No point in taking chances with these guys
8428 though ;-) Note that if you want an ad or obnoxious
8429 URL to be invisible, it should be defined as <quote>ad.doubleclick.net</quote>
8430 is done here -- as both a <link
8431 linkend="BLOCK"><quote>+block{}</quote></link>
8432 <emphasis>and</emphasis> an
8433 <link linkend="HANDLE-AS-IMAGE"><quote>+handle-as-image</quote></link>.
8434 The custom alias <quote><literal>+block-as-image</literal></quote> just
8435 simplifies the process and make it more readable.
8439 One last example. Let's try <quote>http://www.example.net/adsl/HOWTO/</quote>.
8440 This one is giving us problems. We are getting a blank page. Hmmm ...
8446 Matches for http://www.example.net/adsl/HOWTO/:
8448 In file: default.action <guibutton>[ View ]</guibutton> <guibutton>[ Edit ]</guibutton>
8452 +change-x-forwarded-for{block}
8453 -client-header-filter{hide-tor-exit-notation}
8454 -content-type-overwrite
8455 -crunch-client-header
8456 -crunch-if-none-match
8457 -crunch-incoming-cookies
8458 -crunch-outgoing-cookies
8459 -crunch-server-header
8461 -downgrade-http-version
8462 +fast-redirects {check-decoded-url}
8464 -filter {content-cookies}
8465 -filter {all-popups}
8466 -filter {banners-by-link}
8467 -filter {tiny-textforms}
8468 -filter {frameset-borders}
8469 -filter {demoronizer}
8470 -filter {shockwave-flash}
8471 -filter {quicktime-kioskmode}
8473 -filter {crude-parental}
8474 -filter {site-specifics}
8475 -filter {js-annoyances}
8476 -filter {html-annoyances}
8477 +filter {refresh-tags}
8478 -filter {unsolicited-popups}
8479 +filter {img-reorder}
8480 +filter {banners-by-size}
8482 +filter {jumping-windows}
8483 +filter {ie-exploits}
8490 -handle-as-empty-document
8492 -hide-accept-language
8493 -hide-content-disposition
8494 +hide-from-header{block}
8495 +hide-referer{forge}
8497 -overwrite-last-modified
8498 +prevent-compression
8500 -server-header-filter{xml-to-html}
8501 -server-header-filter{html-to-xml}
8502 +session-cookies-only
8503 +set-image-blocker{blank} }
8506 { +block{Path contains "ads".} +handle-as-image }
8512 Ooops, the <quote>/adsl/</quote> is matching <quote>/ads</quote> in our
8513 configuration! But we did not want this at all! Now we see why we get the
8514 blank page. It is actually triggering two different actions here, and
8515 the effects are aggregated so that the URL is blocked, and &my-app; is told
8516 to treat the block as if it were an image. But this is, of course, all wrong.
8517 We could now add a new action below this (or better in our own
8518 <filename>user.action</filename> file) that explicitly
8519 <emphasis>un</emphasis> blocks (
8520 <link linkend="BLOCK"><quote>{-block}</quote></link>) paths with
8521 <quote>adsl</quote> in them (remember, last match in the configuration
8522 wins). There are various ways to handle such exceptions. Example:
8534 Now the page displays ;-)
8535 Remember to flush your browser's caches when making these kinds of changes to
8536 your configuration to insure that you get a freshly delivered page! Or, try
8537 using <literal>Shift+Reload</literal>.
8541 But now what about a situation where we get no explicit matches like
8548 { +block{Path starts with "ads".} +handle-as-image }
8554 That actually was very helpful and pointed us quickly to where the problem
8555 was. If you don't get this kind of match, then it means one of the default
8556 rules in the first section of <filename>default.action</filename> is causing
8557 the problem. This would require some guesswork, and maybe a little trial and
8558 error to isolate the offending rule. One likely cause would be one of the
8559 <link linkend="FILTER"><quote>+filter</quote></link> actions.
8560 These tend to be harder to troubleshoot.
8561 Try adding the URL for the site to one of aliases that turn off
8562 <link linkend="FILTER"><quote>+filter</quote></link>:
8570 .worldpay.com # for quietpc.com
8578 <quote><literal>{ shop }</literal></quote> is an <quote>alias</quote> that expands to
8579 <quote><literal>{ -filter -session-cookies-only }</literal></quote>.
8580 Or you could do your own exception to negate filtering:
8588 # Disable ALL filter actions for sites in this section
8596 This would turn off all filtering for these sites. This is best
8597 put in <filename>user.action</filename>, for local site
8598 exceptions. Note that when a simple domain pattern is used by itself (without
8599 the subsequent path portion), all sub-pages within that domain are included
8600 automatically in the scope of the action.
8604 Images that are inexplicably being blocked, may well be hitting the
8605 <link linkend="FILTER-BANNERS-BY-SIZE"><quote>+filter{banners-by-size}</quote></link>
8607 that images of certain sizes are ad banners (works well
8608 <emphasis>most of the time</emphasis> since these tend to be standardized).
8612 <quote><literal>{ fragile }</literal></quote> is an alias that disables most
8613 actions that are the most likely to cause trouble. This can be used as a
8614 last resort for problem sites.
8620 # Handle with care: easy to break
8622 mybank.example.com</screen>
8627 <emphasis>Remember to flush caches!</emphasis> Note that the
8628 <literal>mail.google</literal> reference lacks the TLD portion (e.g.
8629 <quote>.com</quote>). This will effectively match any TLD with
8630 <literal>google</literal> in it, such as <literal>mail.google.de.</literal>,
8634 If this still does not work, you will have to go through the remaining
8635 actions one by one to find which one(s) is causing the problem.
8644 This program is free software; you can redistribute it
8645 and/or modify it under the terms of the GNU General
8646 Public License as published by the Free Software
8647 Foundation; either version 2 of the License, or (at
8648 your option) any later version.
8650 This program is distributed in the hope that it will
8651 be useful, but WITHOUT ANY WARRANTY; without even the
8652 implied warranty of MERCHANTABILITY or FITNESS FOR A
8653 PARTICULAR PURPOSE. See the GNU General Public
8654 License for more details.
8656 The GNU General Public License should be included with
8657 this file. If not, you can view it at
8658 http://www.gnu.org/copyleft/gpl.html
8659 or write to the Free Software Foundation, Inc.,
8660 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
projects / privoxy.git / blob