1 <!DOCTYPE article PUBLIC "-//OASIS//DTD DocBook V3.1//EN" [
2 <!entity % dummy "IGNORE">
3 <!entity supported SYSTEM "supported.sgml">
4 <!entity newfeatures SYSTEM "newfeatures.sgml">
5 <!entity p-intro SYSTEM "privoxy.sgml">
6 <!entity seealso SYSTEM "seealso.sgml">
7 <!entity buildsource SYSTEM "buildsource.sgml">
8 <!entity contacting SYSTEM "contacting.sgml">
9 <!entity history SYSTEM "history.sgml">
10 <!entity copyright SYSTEM "copyright.sgml">
11 <!entity license SYSTEM "license.sgml">
12 <!entity GPLv2 SYSTEM "../../LICENSE">
13 <!entity p-authors SYSTEM "p-authors.sgml">
14 <!entity config SYSTEM "p-config.sgml">
15 <!entity changelog SYSTEM "changelog.sgml">
16 <!entity p-version "3.0.22">
17 <!entity p-status "UNRELEASED">
18 <!entity % p-authors-formal "INCLUDE"> <!-- include additional text, etc -->
19 <!entity % p-not-stable "INCLUDE">
20 <!entity % p-stable "IGNORE">
21 <!entity % p-text "IGNORE"> <!-- define we are not a text only doc -->
22 <!entity % p-doc "INCLUDE"> <!-- and we are a formal doc -->
23 <!entity % p-readme "IGNORE">
24 <!entity % user-man "IGNORE">
25 <!entity % config-file "IGNORE">
26 <!entity % p-supp-userman "IGNORE"> <!-- Omit some from supported.sgml -->
27 <!entity my-copy "©"> <!-- kludge for docbook2man -->
28 <!entity % draft "IGNORE"> <!-- WIP stuff -->
29 <!entity % seealso-extra "INCLUDE"> <!-- extra stuff from seealso.sgml -->
30 <!entity my-app "<application>Privoxy</application>">
33 File : $Source: /cvsroot/ijbswa/current/doc/source/user-manual.sgml,v $
36 This file belongs into
37 ijbswa.sourceforge.net:/home/groups/i/ij/ijbswa/htdocs/
39 $Id: user-manual.sgml,v 2.182 2014/05/05 10:08:43 fabiankeil Exp $
41 Copyright (C) 2001-2013 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; 2001-2013 by
61 <ulink url="http://www.privoxy.org/">Privoxy Developers</ulink>
65 <pubdate>$Id: user-manual.sgml,v 2.182 2014/05/05 10:08:43 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>.
628 Did anyone test these lately?
632 For easy access to &my-app;'s most important controls, drag the provided
633 <link linkend="bookmarklets">Bookmarklets</link> into your browser's
641 Please see the section <link linkend="contact">Contacting the
642 Developers</link> on how to report bugs, problems with websites or to get
649 Now enjoy surfing with enhanced control, comfort and privacy!
657 <!-- ~~~~~ New section ~~~~~ -->
659 <sect2 id="quickstart-ad-blocking">
660 <title>Quickstart to Ad Blocking</title>
662 NOTE: This section is deliberately redundant for those that don't
663 want to read the whole thing (which is getting lengthy).
666 Ad blocking is but one of <application>Privoxy's</application>
667 array of features. Many of these features are for the technically minded advanced
668 user. But, ad and banner blocking is surely common ground for everybody.
671 This section will provide a quick summary of ad blocking so
672 you can get up to speed quickly without having to read the more extensive
673 information provided below, though this is highly recommended.
676 First a bit of a warning ... blocking ads is much like blocking SPAM: the
677 more aggressive you are about it, the more likely you are to block
678 things that were not intended. And the more likely that some things
679 may not work as intended. So there is a trade off here. If you want
680 extreme ad free browsing, be prepared to deal with more
681 <quote>problem</quote> sites, and to spend more time adjusting the
682 configuration to solve these unintended consequences. In short, there is
683 not an easy way to eliminate <emphasis>all</emphasis> ads. Either take
684 the easy way and settle for <emphasis>most</emphasis> ads blocked with the
685 default configuration, or jump in and tweak it for your personal surfing
686 habits and preferences.
689 Secondly, a brief explanation of <application>Privoxy's </application>
690 <quote>actions</quote>. <quote>Actions</quote> in this context, are
691 the directives we use to tell <application>Privoxy</application> to perform
692 some task relating to HTTP transactions (i.e. web browsing). We tell
693 <application>Privoxy</application> to take some <quote>action</quote>. Each
694 action has a unique name and function. While there are many potential
695 <application>actions</application> in <application>Privoxy's</application>
696 arsenal, only a few are used for ad blocking. <link
697 linkend="actions">Actions</link>, and <link linkend="actions-file">action
698 configuration files</link>, are explained in depth below.
701 Actions are specified in <application>Privoxy's</application> configuration,
702 followed by one or more URLs to which the action should apply. URLs
703 can actually be URL type <link linkend="af-patterns">patterns</link> that use
704 wildcards so they can apply potentially to a range of similar URLs. The
705 actions, together with the URL patterns are called a section.
708 When you connect to a website, the full URL will either match one or more
709 of the sections as defined in <application>Privoxy's</application> configuration,
710 or not. If so, then <application>Privoxy</application> will perform the
711 respective actions. If not, then nothing special happens. Furthermore, web
712 pages may contain embedded, secondary URLs that your web browser will
713 use to load additional components of the page, as it parses the
714 original page's HTML content. An ad image for instance, is just an URL
715 embedded in the page somewhere. The image itself may be on the same server,
716 or a server somewhere else on the Internet. Complex web pages will have many
717 such embedded URLs. &my-app; can deal with each URL individually, so, for
718 instance, the main page text is not touched, but images from such-and-such
723 The most important actions for basic ad blocking are: <literal><link
724 linkend="block">block</link></literal>, <literal><link
725 linkend="handle-as-image">handle-as-image</link></literal>,
727 linkend="handle-as-empty-document">handle-as-empty-document</link></literal>,and
728 <literal><link linkend="set-image-blocker">set-image-blocker</link></literal>:
736 <literal><link linkend="block">block</link></literal> - this is perhaps
737 the single most used action, and is particularly important for ad blocking.
738 This action stops any contact between your browser and any URL patterns
739 that match this action's configuration. It can be used for blocking ads,
740 but also anything that is determined to be unwanted. By itself, it simply
741 stops any communication with the remote server and sends
742 <application>Privoxy</application>'s own built-in BLOCKED page instead to
743 let you now what has happened (with some exceptions, see below).
749 <literal><link linkend="handle-as-image">handle-as-image</link></literal> -
750 tells <application>Privoxy</application> to treat this URL as an image.
751 <application>Privoxy</application>'s default configuration already does this
752 for all common image types (e.g. GIF), but there are many situations where this
753 is not so easy to determine. So we'll force it in these cases. This is particularly
754 important for ad blocking, since only if we know that it's an image of
755 some kind, can we replace it with an image of our choosing, instead of the
756 <application>Privoxy</application> BLOCKED page (which would only result in
757 a <quote>broken image</quote> icon). There are some limitations to this
758 though. For instance, you can't just brute-force an image substitution for
759 an entire HTML page in most situations.
765 <literal><link linkend="handle-as-empty-document">handle-as-empty-document</link></literal> -
766 sends an empty document instead of <application>Privoxy's</application>
767 normal BLOCKED HTML page. This is useful for file types that are neither
768 HTML nor images, such as blocking JavaScript files.
775 linkend="set-image-blocker">set-image-blocker</link></literal> - tells
776 <application>Privoxy</application> what to display in place of an ad image that
777 has hit a block rule. For this to come into play, the URL must match a
778 <literal><link linkend="block">block</link></literal> action somewhere in the
779 configuration, <emphasis>and</emphasis>, it must also match an
780 <literal><link linkend="handle-as-image">handle-as-image</link></literal> action.
783 The configuration options on what to display instead of the ad are:
787 <emphasis>pattern</emphasis> - a checkerboard pattern, so that an ad
788 replacement is obvious. This is the default.
793 <emphasis>blank</emphasis> - A very small empty GIF image is displayed.
794 This is the so-called <quote>invisible</quote> configuration option.
799 <emphasis>http://<URL></emphasis> - A redirect to any image anywhere
800 of the user's choosing (advanced usage).
809 Advanced users will eventually want to explore &my-app;
810 <literal><link linkend="filter">filters</link></literal> as well. Filters
811 are very different from <literal><link
812 linkend="block">blocks</link></literal>.
813 A <quote>block</quote> blocks a site, page, or unwanted contented. Filters
814 are a way of filtering or modifying what is actually on the page. An example
815 filter usage: a text replacement of <quote>no-no</quote> for
816 <quote>nasty-word</quote>. That is a very simple example. This process can be
817 used for ad blocking, but it is more in the realm of advanced usage and has
818 some pitfalls to be wary off.
822 The quickest way to adjust any of these settings is with your browser through
823 the special <application>Privoxy</application> editor at <ulink
824 url="http://config.privoxy.org/show-status">http://config.privoxy.org/show-status</ulink>
825 (shortcut: <ulink url="http://p.p/">http://p.p/show-status</ulink>). This
826 is an internal page, and does not require Internet access.
830 Note that as of <application>Privoxy</application> 3.0.7 beta the
831 action editor is disabled by default. Check the
832 <ulink url="config.html#ENABLE-EDIT-ACTIONS">enable-edit-actions
833 section in the configuration file</ulink> to learn why and in which
834 cases it's safe to enable again.
838 If you decided to enable the action editor, select the appropriate
839 <quote>actions</quote> file, and click
840 <quote><guibutton>Edit</guibutton></quote>. It is best to put personal or
841 local preferences in <filename>user.action</filename> since this is not
842 meant to be overwritten during upgrades, and will over-ride the settings in
843 other files. Here you can insert new <quote>actions</quote>, and URLs for ad
844 blocking or other purposes, and make other adjustments to the configuration.
845 <application>Privoxy</application> will detect these changes automatically.
849 A quick and simple step by step example:
857 Right click on the ad image to be blocked, then select
858 <quote><guimenuitem>Copy Link Location</guimenuitem></quote> from the
866 url="http://config.privoxy.org/show-status">http://config.privoxy.org/show-status</ulink>
871 Find <filename>user.action</filename> in the top section, and click
872 on <quote><guibutton>Edit</guibutton></quote>:
875 <!-- image of editor and actions files selections -->
877 <figure pgwide="0" float="0"><title>Actions Files in Use</title>
880 <imagedata fileref="files-in-use.jpg" format="jpg">
883 <phrase>[ Screenshot of Actions Files in Use ]</phrase>
892 You should have a section with only
893 <literal><link linkend="block">block</link></literal> listed under
894 <quote>Actions:</quote>.
895 If not, click a <quote><guibutton>Insert new section below</guibutton></quote>
896 button, and in the new section that just appeared, click the
897 <guibutton>Edit</guibutton> button right under the word <quote>Actions:</quote>.
898 This will bring up a list of all actions. Find
899 <literal><link linkend="block">block</link></literal> near the top, and click
900 in the <quote>Enabled</quote> column, then <quote><guibutton>Submit</guibutton></quote>
906 Now, in the <literal><link linkend="block">block</link></literal> actions section,
907 click the <quote><guibutton>Add</guibutton></quote> button, and paste the URL the
908 browser got from <quote><guimenuitem>Copy Link Location</guimenuitem></quote>.
909 Remove the <literal>http://</literal> at the beginning of the URL. Then, click
910 <quote><guibutton>Submit</guibutton></quote> (or
911 <quote><guibutton>OK</guibutton></quote> if in a pop-up window).
916 Now go back to the original page, and press <keycap>SHIFT-Reload</keycap>
917 (or flush all browser caches). The image should be gone now.
925 This is a very crude and simple example. There might be good reasons to use a
926 wildcard pattern match to include potentially similar images from the same
927 site. For a more extensive explanation of <quote>patterns</quote>, and
928 the entire actions concept, see <link linkend="actions-file">the Actions
933 For advanced users who want to hand edit their config files, you might want
934 to now go to the <link linkend="act-examples">Actions Files Tutorial</link>.
935 The ideas explained therein also apply to the web-based editor.
938 There are also various
939 <link linkend="filter">filters</link> that can be used for ad blocking
940 (filters are a special subset of actions). These
941 fall into the <quote>advanced</quote> usage category, and are explained in
942 depth in later sections.
949 <!-- ~ End section ~ -->
952 <!-- ~~~~~ New section ~~~~~ -->
954 <title>Starting Privoxy</title>
956 Before launching <application>Privoxy</application> for the first time, you
957 will want to configure your browser(s) to use
958 <application>Privoxy</application> as a HTTP and HTTPS (SSL)
959 <ulink url="http://en.wikipedia.org/wiki/Proxy_server">proxy</ulink>. The default is
960 127.0.0.1 (or localhost) for the proxy address, and port 8118 (earlier versions
961 used port 8000). This is the one configuration step <emphasis>that must be done
965 Please note that <application>Privoxy</application> can only proxy HTTP and
966 HTTPS traffic. It will not work with FTP or other protocols.
969 <!-- image of Mozilla Proxy configuration -->
971 <figure pgwide="0" float="0"><title>Proxy Configuration Showing
972 Mozilla/Netscape HTTP and HTTPS (SSL) Settings</title>
975 <imagedata fileref="proxy_setup.jpg" format="jpg">
978 <phrase>[ Screenshot of Mozilla Proxy Configuration ]</phrase>
986 With <application>Firefox</application>, this is typically set under:
990 <guibutton>Tools</guibutton> -> <guibutton>Options</guibutton> -> <guibutton>Advanced</guibutton> -> <guibutton>Network</guibutton> -><guibutton>Connection</guibutton> -> <guibutton>Settings</guibutton>
995 Or optionally on some platforms:
999 <guibutton>Edit</guibutton> -> <guibutton>Preferences</guibutton> -> <guibutton>General</guibutton> -> <guibutton>Connection Settings</guibutton> -> <guibutton>Manual Proxy Configuration</guibutton>
1005 With <application>Netscape</application> (and
1006 <application>Mozilla</application>), this can be set under:
1011 <!-- Mix ascii and gui art, something for everybody -->
1012 <!-- spacing on this is tricky -->
1013 <guibutton>Edit</guibutton> -> <guibutton>Preferences</guibutton> -> <guibutton>Advanced</guibutton> -> <guibutton>Proxies</guibutton> -> <guibutton>HTTP Proxy</guibutton>
1018 For <application>Internet Explorer v.5-7</application>:
1022 <guibutton>Tools</guibutton> -> <guibutton>Internet Options</guibutton> -> <guibutton>Connections</guibutton> -> <guibutton>LAN Settings</guibutton>
1026 Then, check <quote>Use Proxy</quote> and fill in the appropriate info
1027 (Address: 127.0.0.1, Port: 8118). Include HTTPS (SSL), if you want HTTPS
1028 proxy support too (sometimes labeled <quote>Secure</quote>). Make sure any
1029 checkboxes like <quote>Use the same proxy server for all protocols</quote> is
1030 <emphasis>UNCHECKED</emphasis>. You want only HTTP and HTTPS (SSL)!
1033 <!-- image of IE Proxy configuration -->
1035 <figure pgwide="0" float="0"><title>Proxy Configuration Showing
1036 Internet Explorer HTTP and HTTPS (Secure) Settings</title>
1039 <imagedata fileref="proxy2.jpg" format="jpg">
1042 <phrase>[ Screenshot of IE Proxy Configuration ]</phrase>
1050 After doing this, flush your browser's disk and memory caches to force a
1051 re-reading of all pages and to get rid of any ads that may be cached. Remove
1052 any <ulink url="http://en.wikipedia.org/wiki/Browser_cookie">cookies</ulink>,
1053 if you want <application>Privoxy</application> to manage that. You are now
1054 ready to start enjoying the benefits of using
1055 <application>Privoxy</application>!
1059 <application>Privoxy</application> itself is typically started by specifying the
1060 main configuration file to be used on the command line. If no configuration
1061 file is specified on the command line, <application>Privoxy</application>
1062 will look for a file named <filename>config</filename> in the current
1063 directory. Except on Win32 where it will try <filename>config.txt</filename>.
1066 <sect2 id="start-debian">
1067 <title>Debian</title>
1069 We use a script. Note that Debian typically starts &my-app; upon booting per
1070 default. It will use the file
1071 <filename>/etc/privoxy/config</filename> as its main configuration
1076 # /etc/init.d/privoxy start
1081 <sect2 id="start-windows">
1082 <title>Windows</title>
1084 Click on the &my-app; Icon to start <application>Privoxy</application>. If no configuration file is
1085 specified on the command line, <application>Privoxy</application> will look
1086 for a file named <filename>config.txt</filename>. Note that Windows will
1087 automatically start &my-app; when the system starts if you chose that option
1091 <application>Privoxy</application> can run with full Windows service functionality.
1092 On Windows only, the &my-app; program has two new command line arguments
1093 to install and uninstall &my-app; as a service. See the
1094 <link linkend="installation-pack-win">Windows Installation
1095 instructions</link> for details.
1099 <sect2 id="start-unices">
1100 <title>Solaris, NetBSD, FreeBSD, HP-UX and others</title>
1102 Example Unix startup command:
1106 # /usr/sbin/privoxy /etc/privoxy/config
1111 <sect2 id="start-os2">
1114 During installation, <application>Privoxy</application> is configured to
1115 start automatically when the system restarts. You can start it manually by
1116 double-clicking on the <application>Privoxy</application> icon in the
1117 <application>Privoxy</application> folder.
1121 <sect2 id="start-macosx">
1122 <title>Mac OS X</title>
1124 After downloading the privoxy software, unzip the downloaded file by
1125 double-clicking on the zip file icon. Then, double-click on the
1126 installer package icon and follow the installation process.
1129 The privoxy service will automatically start after a successful
1130 installation. In addition, the privoxy service will automatically
1131 start every time your computer starts up.
1134 To prevent the privoxy service from automatically starting when your
1135 computer starts up, remove or rename the folder named
1136 /Library/StartupItems/Privoxy.
1139 A simple application named Privoxy Utility has been created which
1140 enables administrators to easily start and stop the privoxy service.
1143 In addition, the Privoxy Utility presents a simple way for
1144 administrators to edit the various privoxy config files. A method
1145 to uninstall the software is also available.
1148 An administrator username and password must be supplied in order for
1149 the Privoxy Utility to perform any of the tasks.
1157 See the section <link linkend="cmdoptions">Command line options</link> for
1161 must find a better place for this paragraph
1164 The included default configuration files should give a reasonable starting
1165 point. Most of the per site configuration is done in the
1166 <ulink url="actions-file.html"><quote>actions</quote></ulink> files. These are
1167 where various cookie actions are defined, ad and banner blocking, and other
1168 aspects of <application>Privoxy</application> configuration. There are several
1169 such files included, with varying levels of aggressiveness.
1173 You will probably want to keep an eye out for sites for which you may prefer
1174 persistent cookies, and add these to your actions configuration as needed. By
1175 default, most of these will be accepted only during the current browser
1176 session (aka <quote>session cookies</quote>), unless you add them to the
1177 configuration. If you want the browser to handle this instead, you will need
1178 to edit <filename>user.action</filename> (or through the web based interface)
1179 and disable this feature. If you use more than one browser, it would make
1180 more sense to let <application>Privoxy</application> handle this. In which
1181 case, the browser(s) should be set to accept all cookies.
1185 Another feature where you will probably want to define exceptions for trusted
1186 sites is the popup-killing (through <ulink
1187 url="actions-file.html#FILTER-POPUPS"><quote>+filter{popups}</quote></ulink>),
1188 because your favorite shopping, banking, or leisure site may need
1189 popups (explained below).
1193 <application>Privoxy</application> does not support all of the optional HTTP/1.1
1194 features yet. In the unlikely event that you experience inexplicable problems
1195 with browsers that use HTTP/1.1 per default
1196 (like <application>Mozilla</application> or recent versions of I.E.), you might
1197 try to force HTTP/1.0 compatibility. For Mozilla, look under <literal>Edit ->
1198 Preferences -> Debug -> Networking</literal>.
1199 Alternatively, set the <quote>+downgrade-http-version</quote> config option in
1200 <filename>default.action</filename> which will downgrade your browser's HTTP
1201 requests from HTTP/1.1 to HTTP/1.0 before processing them.
1205 After running <application>Privoxy</application> for a while, you can
1206 start to fine tune the configuration to suit your personal, or site,
1207 preferences and requirements. There are many, many aspects that can
1208 be customized. <quote>Actions</quote>
1209 can be adjusted by pointing your browser to
1210 <ulink url="http://config.privoxy.org/">http://config.privoxy.org/</ulink>
1211 (shortcut: <ulink url="http://p.p/">http://p.p/</ulink>),
1212 and then follow the link to <quote>View & Change the Current Configuration</quote>.
1213 (This is an internal page and does not require Internet access.)
1217 In fact, various aspects of <application>Privoxy</application>
1218 configuration can be viewed from this page, including
1219 current configuration parameters, source code version numbers,
1220 the browser's request headers, and <quote>actions</quote> that apply
1221 to a given URL. In addition to the actions file
1222 editor mentioned above, <application>Privoxy</application> can also
1223 be turned <quote>on</quote> and <quote>off</quote> (toggled) from this page.
1227 If you encounter problems, try loading the page without
1228 <application>Privoxy</application>. If that helps, enter the URL where
1229 you have the problems into <ulink url="http://p.p/show-url-info">the browser
1230 based rule tracing utility</ulink>. See which rules apply and why, and
1231 then try turning them off for that site one after the other, until the problem
1232 is gone. When you have found the culprit, you might want to turn the rest on
1237 If the above paragraph sounds gibberish to you, you might want to <link
1238 linkend="actions-file">read more about the actions concept</link>
1239 or even dive deep into the <link linkend="actionsanat">Appendix
1244 If you can't get rid of the problem at all, think you've found a bug in
1245 Privoxy, want to propose a new feature or smarter rules, please see the
1246 section <link linkend="contact"><quote>Contacting the
1247 Developers</quote></link> below.
1252 <!-- ~~~~~ New section ~~~~~ -->
1253 <sect2 id="cmdoptions">
1254 <title>Command Line Options</title>
1256 <application>Privoxy</application> may be invoked with the following
1257 command-line options:
1265 <emphasis>--config-test</emphasis>
1268 Exit after loading the configuration files before binding to
1269 the listen address. The exit code signals whether or not the
1270 configuration files have been successfully loaded.
1273 If the exit code is 1, at least one of the configuration files
1274 is invalid, if it is 0, all the configuration files have been
1275 successfully loaded (but may still contain errors that can
1276 currently only be detected at run time).
1279 This option doesn't affect the log setting, combination with
1280 <emphasis>--no-daemon</emphasis> is recommended if a configured
1281 log file shouldn't be used.
1286 <emphasis>--version</emphasis>
1289 Print version info and exit. Unix only.
1294 <emphasis>--help</emphasis>
1297 Print short usage info and exit. Unix only.
1302 <emphasis>--no-daemon</emphasis>
1305 Don't become a daemon, i.e. don't fork and become process group
1306 leader, and don't detach from controlling tty. Unix only.
1311 <emphasis>--pidfile FILE</emphasis>
1314 On startup, write the process ID to <emphasis>FILE</emphasis>. Delete the
1315 <emphasis>FILE</emphasis> on exit. Failure to create or delete the
1316 <emphasis>FILE</emphasis> is non-fatal. If no <emphasis>FILE</emphasis>
1317 option is given, no PID file will be used. Unix only.
1322 <emphasis>--user USER[.GROUP]</emphasis>
1325 After (optionally) writing the PID file, assume the user ID of
1326 <emphasis>USER</emphasis>, and if included the GID of GROUP. Exit if the
1327 privileges are not sufficient to do so. Unix only.
1332 <emphasis>--chroot</emphasis>
1335 Before changing to the user ID given in the <emphasis>--user</emphasis> option,
1336 chroot to that user's home directory, i.e. make the kernel pretend to the &my-app;
1337 process that the directory tree starts there. If set up carefully, this can limit
1338 the impact of possible vulnerabilities in &my-app; to the files contained in that hierarchy.
1344 <emphasis>--pre-chroot-nslookup hostname</emphasis>
1347 Specifies a hostname (for example www.privoxy.org) to look up before doing a chroot.
1348 On some systems, initializing the resolver library involves reading config files from
1349 /etc and/or loading additional shared libraries from /lib.
1350 On these systems, doing a hostname lookup before the chroot reduces
1351 the number of files that must be copied into the chroot tree.
1354 For fastest startup speed, a good value is a hostname that is not in /etc/hosts but that
1355 your local name server (listed in /etc/resolv.conf) can resolve without recursion
1356 (that is, without having to ask any other name servers). The hostname need not exist,
1357 but if it doesn't, an error message (which can be ignored) will be output.
1363 <emphasis>configfile</emphasis>
1366 If no <emphasis>configfile</emphasis> is included on the command line,
1367 <application>Privoxy</application> will look for a file named
1368 <quote>config</quote> in the current directory (except on Win32
1369 where it will look for <quote>config.txt</quote> instead). Specify
1370 full path to avoid confusion. If no config file is found,
1371 <application>Privoxy</application> will fail to start.
1379 On <application>MS Windows</application> only there are two additional
1380 command-line options to allow <application>Privoxy</application> to install and
1381 run as a <emphasis>service</emphasis>. See the
1382 <link linkend="installation-pack-win">Window Installation section</link>
1390 <!-- ~ End section ~ -->
1393 <!-- ~~~~~ New section ~~~~~ -->
1394 <sect1 id="configuration"><title>Privoxy Configuration</title>
1396 All <application>Privoxy</application> configuration is stored
1397 in text files. These files can be edited with a text editor.
1398 Many important aspects of <application>Privoxy</application> can
1399 also be controlled easily with a web browser.
1403 <!-- ~~~~~ New section ~~~~~ -->
1406 <title>Controlling Privoxy with Your Web Browser</title>
1408 <application>Privoxy</application>'s user interface can be reached through the special
1409 URL <ulink url="http://config.privoxy.org/">http://config.privoxy.org/</ulink>
1410 (shortcut: <ulink url="http://p.p/">http://p.p/</ulink>),
1411 which is a built-in page and works without Internet access.
1412 You will see the following section:
1416 <!-- Needs to be put in a table and colorized -->
1419 <bridgehead renderas="sect2"> Privoxy Menu</bridgehead>
1423 ▪ <ulink url="http://config.privoxy.org/show-status">View & change the current configuration</ulink>
1426 ▪ <ulink url="http://config.privoxy.org/show-version">View the source code version numbers</ulink>
1429 ▪ <ulink url="http://config.privoxy.org/show-request">View the request headers.</ulink>
1432 ▪ <ulink url="http://config.privoxy.org/show-url-info">Look up which actions apply to a URL and why</ulink>
1435 ▪ <ulink url="http://config.privoxy.org/toggle">Toggle Privoxy on or off</ulink>
1438 ▪ <ulink
1439 url="http://www.privoxy.org/&p-version;/user-manual/">Documentation</ulink>
1447 This should be self-explanatory. Note the first item leads to an editor for the
1448 <link linkend="actions-file">actions files</link>, which is where the ad, banner,
1449 cookie, and URL blocking magic is configured as well as other advanced features of
1450 <application>Privoxy</application>. This is an easy way to adjust various
1451 aspects of <application>Privoxy</application> configuration. The actions
1452 file, and other configuration files, are explained in detail below.
1456 <quote>Toggle Privoxy On or Off</quote> is handy for sites that might
1457 have problems with your current actions and filters. You can in fact use
1458 it as a test to see whether it is <application>Privoxy</application>
1459 causing the problem or not. <application>Privoxy</application> continues
1460 to run as a proxy in this case, but all manipulation is disabled, i.e.
1461 <application>Privoxy</application> acts like a normal forwarding proxy. There
1462 is even a toggle <link linkend="bookmarklets">Bookmarklet</link> offered, so
1463 that you can toggle <application>Privoxy</application> with one click from
1468 Note that several of the features described above are disabled by default
1469 in <application>Privoxy</application> 3.0.7 beta and later.
1471 <ulink url="config.html">configuration file</ulink> to learn why
1472 and in which cases it's safe to enable them again.
1477 <!-- ~ End section ~ -->
1482 <!-- ~~~~~ New section ~~~~~ -->
1484 <sect2 id="confoverview">
1485 <title>Configuration Files Overview</title>
1487 For Unix, *BSD and Linux, all configuration files are located in
1488 <filename>/etc/privoxy/</filename> by default. For MS Windows, OS/2, and
1489 AmigaOS these are all in the same directory as the
1490 <application>Privoxy</application> executable. <![%p-not-stable;[ The name
1491 and number of configuration files has changed from previous versions, and is
1492 subject to change as development progresses.]]>
1496 The installed defaults provide a reasonable starting point, though
1497 some settings may be aggressive by some standards. For the time being, the
1498 principle configuration files are:
1506 The <link linkend="config">main configuration file</link> is named <filename>config</filename>
1507 on Linux, Unix, BSD, OS/2, and AmigaOS and <filename>config.txt</filename>
1508 on Windows. This is a required file.
1514 <filename>match-all.action</filename> is used to define which <quote>actions</quote>
1515 relating to banner-blocking, images, pop-ups, content modification, cookie handling
1516 etc should be applied by default. It should be the first actions file loaded.
1519 <filename>default.action</filename> defines many exceptions (both positive and negative)
1520 from the default set of actions that's configured in <filename>match-all.action</filename>.
1521 It should be the second actions file loaded and shouldn't be edited by the user.
1524 Multiple actions files may be defined in <filename>config</filename>. These
1525 are processed in the order they are defined. Local customizations and locally
1526 preferred exceptions to the default policies as defined in
1527 <filename>match-all.action</filename> (which you will most probably want
1528 to define sooner or later) are best applied in <filename>user.action</filename>,
1529 where you can preserve them across upgrades. The file isn't installed by all
1530 installers, but you can easily create it yourself with a text editor.
1533 There is also a web based editor that can be accessed from
1535 url="http://config.privoxy.org/show-status">http://config.privoxy.org/show-status</ulink>
1537 url="http://p.p/show-status">http://p.p/show-status</ulink>) for the
1538 various actions files.
1544 <quote>Filter files</quote> (the <link linkend="filter-file">filter
1545 file</link>) can be used to re-write the raw page content, including
1546 viewable text as well as embedded HTML and JavaScript, and whatever else
1547 lurks on any given web page. The filtering jobs are only pre-defined here;
1548 whether to apply them or not is up to the actions files.
1549 <filename>default.filter</filename> includes various filters made
1550 available for use by the developers. Some are much more intrusive than
1551 others, and all should be used with caution. You may define additional
1552 filter files in <filename>config</filename> as you can with
1553 actions files. We suggest <filename>user.filter</filename> for any
1554 locally defined filters or customizations.
1562 The syntax of the configuration and filter files may change between different
1563 Privoxy versions, unfortunately some enhancements cost backwards compatibility.
1564 <!-- Add link to documentation-->
1568 All files use the <quote><literal>#</literal></quote> character to denote a
1569 comment (the rest of the line will be ignored) and understand line continuation
1570 through placing a backslash ("<literal>\</literal>") as the very last character
1571 in a line. If the <literal>#</literal> is preceded by a backslash, it looses
1572 its special function. Placing a <literal>#</literal> in front of an otherwise
1573 valid configuration line to prevent it from being interpreted is called "commenting
1574 out" that line. Blank lines are ignored.
1578 The actions files and filter files
1579 can use Perl style <link linkend="regex">regular expressions</link> for
1580 maximum flexibility.
1584 After making any changes, there is no need to restart
1585 <application>Privoxy</application> in order for the changes to take
1586 effect. <application>Privoxy</application> detects such changes
1587 automatically. Note, however, that it may take one or two additional
1588 requests for the change to take effect. When changing the listening address
1589 of <application>Privoxy</application>, these <quote>wake up</quote> requests
1590 must obviously be sent to the <emphasis>old</emphasis> listening address.
1595 While under development, the configuration content is subject to change.
1596 The below documentation may not be accurate by the time you read this.
1597 Also, what constitutes a <quote>default</quote> setting, may change, so
1598 please check all your configuration files on important issues.
1604 <!-- ~ End section ~ -->
1607 <!-- ~~~~~~~~ New section Header ~~~~~~~~~ -->
1609 <!-- **************************************************** -->
1610 <!-- Include config.sgml here -->
1611 <!-- This is where the entire config file is detailed. -->
1613 <!-- end include -->
1616 <!-- ~ End section ~ -->
1620 <!-- ~~~~~~~~ New section Header ~~~~~~~~~ -->
1622 <sect1 id="actions-file"><title>Actions Files</title>
1626 XXX: similar descriptions are in the Configuration Files sections.
1627 We should only describe them at one place.
1630 The actions files are used to define what <emphasis>actions</emphasis>
1631 <application>Privoxy</application> takes for which URLs, and thus determines
1632 how ad images, cookies and various other aspects of HTTP content and
1633 transactions are handled, and on which sites (or even parts thereof).
1634 There are a number of such actions, with a wide range of functionality.
1635 Each action does something a little different.
1636 These actions give us a veritable arsenal of tools with which to exert
1637 our control, preferences and independence. Actions can be combined so that
1638 their effects are aggregated when applied against a given set of URLs.
1642 are three action files included with <application>Privoxy</application> with
1649 <filename>match-all.action</filename> - is used to define which
1650 <quote>actions</quote> relating to banner-blocking, images, pop-ups,
1651 content modification, cookie handling etc should be applied by default.
1652 It should be the first actions file loaded
1657 <filename>default.action</filename> - defines many exceptions (both
1658 positive and negative) from the default set of actions that's configured
1659 in <filename>match-all.action</filename>. It is a set of rules that should
1660 work reasonably well as-is for most users. This file is only supposed to
1661 be edited by the developers. It should be the second actions file loaded.
1666 <filename>user.action</filename> - is intended to be for local site
1667 preferences and exceptions. As an example, if your ISP or your bank
1668 has specific requirements, and need special handling, this kind of
1669 thing should go here. This file will not be upgraded.
1674 <guibutton>Edit</guibutton> <guibutton>Set to Cautious</guibutton> <guibutton>Set to Medium</guibutton> <guibutton>Set to Advanced</guibutton>
1677 These have increasing levels of aggressiveness <emphasis>and have no
1678 influence on your browsing unless you select them explicitly in the
1679 editor</emphasis>. A default installation should be pre-set to
1680 <literal>Cautious</literal>. New users should try this for a while before
1681 adjusting the settings to more aggressive levels. The more aggressive
1682 the settings, then the more likelihood there is of problems such as sites
1683 not working as they should.
1686 The <guibutton>Edit</guibutton> button allows you to turn each
1687 action on/off individually for fine-tuning. The <guibutton>Cautious</guibutton>
1688 button changes the actions list to low/safe settings which will activate
1689 ad blocking and a minimal set of &my-app;'s features, and subsequently
1690 there will be less of a chance for accidental problems. The
1691 <guibutton>Medium</guibutton> button sets the list to a medium level of
1692 other features and a low level set of privacy features. The
1693 <guibutton>Advanced</guibutton> button sets the list to a high level of
1694 ad blocking and medium level of privacy. See the chart below. The latter
1695 three buttons over-ride any changes via with the
1696 <guibutton>Edit</guibutton> button. More fine-tuning can be done in the
1697 lower sections of this internal page.
1700 While the actions file editor allows to enable these settings in all
1701 actions files, they are only supposed to be enabled in the first one
1702 to make sure you don't unintentionally overrule earlier rules.
1705 The default profiles, and their associated actions, as pre-defined in
1706 <filename>default.action</filename> are:
1709 <table frame=all><title>Default Configurations</title>
1710 <tgroup cols=4 align=left colsep=1 rowsep=1>
1711 <colspec colname=c1>
1712 <colspec colname=c2>
1713 <colspec colname=c3>
1714 <colspec colname=c4>
1717 <entry>Feature</entry>
1718 <entry>Cautious</entry>
1719 <entry>Medium</entry>
1720 <entry>Advanced</entry>
1725 <!-- <entry>f1</entry> -->
1726 <!-- <entry>f2</entry> -->
1727 <!-- <entry>f3</entry> -->
1728 <!-- <entry>f4</entry> -->
1734 <entry>Ad-blocking Aggressiveness</entry>
1735 <entry>medium</entry>
1741 <entry>Ad-filtering by size</entry>
1748 <entry>Ad-filtering by link</entry>
1754 <entry>Pop-up killing</entry>
1755 <entry>blocks only</entry>
1756 <entry>blocks only</entry>
1757 <entry>blocks only</entry>
1761 <entry>Privacy Features</entry>
1763 <entry>medium</entry>
1764 <entry>medium/high</entry>
1768 <entry>Cookie handling</entry>
1770 <entry>session-only</entry>
1775 <entry>Referer forging</entry>
1782 <entry>GIF de-animation</entry>
1789 <entry>Fast redirects</entry>
1796 <entry>HTML taming</entry>
1803 <entry>JavaScript taming</entry>
1810 <entry>Web-bug killing</entry>
1817 <entry>Image tag reordering</entry>
1833 The list of actions files to be used are defined in the main configuration
1834 file, and are processed in the order they are defined (e.g.
1835 <filename>default.action</filename> is typically processed before
1836 <filename>user.action</filename>). The content of these can all be viewed and
1838 url="http://config.privoxy.org/show-status">http://config.privoxy.org/show-status</ulink>.
1839 The over-riding principle when applying actions, is that the last action that
1840 matches a given URL wins. The broadest, most general rules go first
1841 (defined in <filename>default.action</filename>),
1842 followed by any exceptions (typically also in
1843 <filename>default.action</filename>), which are then followed lastly by any
1844 local preferences (typically in <emphasis>user</emphasis><filename>.action</filename>).
1845 Generally, <filename>user.action</filename> has the last word.
1849 An actions file typically has multiple sections. If you want to use
1850 <quote>aliases</quote> in an actions file, you have to place the (optional)
1851 <link linkend="aliases">alias section</link> at the top of that file.
1852 Then comes the default set of rules which will apply universally to all
1853 sites and pages (be <emphasis>very careful</emphasis> with using such a
1854 universal set in <filename>user.action</filename> or any other actions file after
1855 <filename>default.action</filename>, because it will override the result
1856 from consulting any previous file). And then below that,
1857 exceptions to the defined universal policies. You can regard
1858 <filename>user.action</filename> as an appendix to <filename>default.action</filename>,
1859 with the advantage that it is a separate file, which makes preserving your
1860 personal settings across <application>Privoxy</application> upgrades easier.
1864 Actions can be used to block anything you want, including ads, banners, or
1865 just some obnoxious URL whose content you would rather not see. Cookies can be accepted
1866 or rejected, or accepted only during the current browser session (i.e. not
1867 written to disk), content can be modified, some JavaScripts tamed, user-tracking
1868 fooled, and much more. See below for a <link linkend="actions">complete list
1872 <!-- ~~~~~ New section ~~~~~ -->
1874 <title>Finding the Right Mix</title>
1876 Note that some <link linkend="actions">actions</link>, like cookie suppression
1877 or script disabling, may render some sites unusable that rely on these
1878 techniques to work properly. Finding the right mix of actions is not always easy and
1879 certainly a matter of personal taste. And, things can always change, requiring
1880 refinements in the configuration. In general, it can be said that the more
1881 <quote>aggressive</quote> your default settings (in the top section of the
1882 actions file) are, the more exceptions for <quote>trusted</quote> sites you
1883 will have to make later. If, for example, you want to crunch all cookies per
1884 default, you'll have to make exceptions from that rule for sites that you
1885 regularly use and that require cookies for actually useful purposes, like maybe
1886 your bank, favorite shop, or newspaper.
1890 We have tried to provide you with reasonable rules to start from in the
1891 distribution actions files. But there is no general rule of thumb on these
1892 things. There just are too many variables, and sites are constantly changing.
1893 Sooner or later you will want to change the rules (and read this chapter again :).
1897 <!-- ~~~~~ New section ~~~~~ -->
1899 <title>How to Edit</title>
1901 The easiest way to edit the actions files is with a browser by
1902 using our browser-based editor, which can be reached from <ulink
1903 url="http://config.privoxy.org/show-status">http://config.privoxy.org/show-status</ulink>.
1904 Note: the config file option <link
1905 linkend="enable-edit-actions">enable-edit-actions</link> must be enabled for
1906 this to work. The editor allows both fine-grained control over every single
1907 feature on a per-URL basis, and easy choosing from wholesale sets of defaults
1908 like <quote>Cautious</quote>, <quote>Medium</quote> or
1909 <quote>Advanced</quote>. Warning: the <quote>Advanced</quote> setting is more
1910 aggressive, and will be more likely to cause problems for some sites.
1911 Experienced users only!
1915 If you prefer plain text editing to GUIs, you can of course also directly edit the
1916 the actions files with your favorite text editor. Look at
1917 <filename>default.action</filename> which is richly commented with many
1923 <sect2 id="actions-apply">
1924 <title>How Actions are Applied to Requests</title>
1926 Actions files are divided into sections. There are special sections,
1927 like the <quote><link linkend="aliases">alias</link></quote> sections which will
1928 be discussed later. For now let's concentrate on regular sections: They have a
1929 heading line (often split up to multiple lines for readability) which consist
1930 of a list of actions, separated by whitespace and enclosed in curly braces.
1931 Below that, there is a list of URL and tag patterns, each on a separate line.
1935 To determine which actions apply to a request, the URL of the request is
1936 compared to all URL patterns in each <quote>action file</quote>.
1937 Every time it matches, the list of applicable actions for the request is
1938 incrementally updated, using the heading of the section in which the
1939 pattern is located. The same is done again for tags and tag patterns later on.
1943 If multiple applying sections set the same action differently,
1944 the last match wins. If not, the effects are aggregated.
1945 E.g. a URL might match a regular section with a heading line of <literal>{
1946 +<link linkend="handle-as-image">handle-as-image</link> }</literal>,
1947 then later another one with just <literal>{
1948 +<link linkend="block">block</link> }</literal>, resulting
1949 in <emphasis>both</emphasis> actions to apply. And there may well be
1950 cases where you will want to combine actions together. Such a section then
1956 { +<literal>handle-as-image</literal> +<literal>block{Banner ads.}</literal> }
1957 # Block these as if they were images. Send no block page.
1959 media.example.com/.*banners
1960 .example.com/images/ads/</screen>
1964 You can trace this process for URL patterns and any given URL by visiting <ulink
1965 url="http://config.privoxy.org/show-url-info">http://config.privoxy.org/show-url-info</ulink>.
1969 Examples and more detail on this is provided in the Appendix, <link linkend="ACTIONSANAT">
1970 Troubleshooting: Anatomy of an Action</link> section.
1974 <!-- ~~~~~ New section ~~~~~ -->
1975 <sect2 id="af-patterns">
1976 <title>Patterns</title>
1978 As mentioned, <application>Privoxy</application> uses <quote>patterns</quote>
1979 to determine what <emphasis>actions</emphasis> might apply to which sites and
1980 pages your browser attempts to access. These <quote>patterns</quote> use wild
1981 card type <emphasis>pattern</emphasis> matching to achieve a high degree of
1982 flexibility. This allows one expression to be expanded and potentially match
1983 against many similar patterns.
1987 Generally, an URL pattern has the form
1988 <literal><host><port>/<path></literal>, where the
1989 <literal><host></literal>, the <literal><port></literal>
1990 and the <literal><path></literal> are optional. (This is why the special
1991 <literal>/</literal> pattern matches all URLs). Note that the protocol
1992 portion of the URL pattern (e.g. <literal>http://</literal>) should
1993 <emphasis>not</emphasis> be included in the pattern. This is assumed already!
1996 The pattern matching syntax is different for the host and path parts of
1997 the URL. The host part uses a simple globbing type matching technique,
1998 while the path part uses more flexible
1999 <ulink url="http://en.wikipedia.org/wiki/Regular_expressions"><quote>Regular
2000 Expressions</quote></ulink> (POSIX 1003.2).
2003 The port part of a pattern is a decimal port number preceded by a colon
2004 (<literal>:</literal>). If the host part contains a numerical IPv6 address,
2005 it has to be put into angle brackets
2006 (<literal><</literal>, <literal>></literal>).
2011 <term><literal>www.example.com/</literal></term>
2014 is a host-only pattern and will match any request to <literal>www.example.com</literal>,
2015 regardless of which document on that server is requested. So ALL pages in
2016 this domain would be covered by the scope of this action. Note that a
2017 simple <literal>example.com</literal> is different and would NOT match.
2022 <term><literal>www.example.com</literal></term>
2025 means exactly the same. For host-only patterns, the trailing <literal>/</literal> may
2031 <term><literal>www.example.com/index.html</literal></term>
2034 matches all the documents on <literal>www.example.com</literal>
2035 whose name starts with <literal>/index.html</literal>.
2040 <term><literal>www.example.com/index.html$</literal></term>
2043 matches only the single document <literal>/index.html</literal>
2044 on <literal>www.example.com</literal>.
2049 <term><literal>/index.html$</literal></term>
2052 matches the document <literal>/index.html</literal>, regardless of the domain,
2053 i.e. on <emphasis>any</emphasis> web server anywhere.
2058 <term><literal>/</literal></term>
2061 Matches any URL because there's no requirement for either the
2062 domain or the path to match anything.
2067 <term><literal>:8000/</literal></term>
2070 Matches any URL pointing to TCP port 8000.
2075 <term><literal>10.0.0.1/</literal></term>
2078 Matches any URL with the host address <literal>10.0.0.1</literal>.
2079 (Note that the real URL uses plain brackets, not angle brackets.)
2084 <term><literal><2001:db8::1>/</literal></term>
2087 Matches any URL with the host address <literal>2001:db8::1</literal>.
2088 (Note that the real URL uses plain brackets, not angle brackets.)
2093 <term><literal>index.html</literal></term>
2096 matches nothing, since it would be interpreted as a domain name and
2097 there is no top-level domain called <literal>.html</literal>. So its
2105 <!-- ~~~~~ New section ~~~~~ -->
2106 <sect3 id="host-pattern"><title>The Host Pattern</title>
2109 The matching of the host part offers some flexible options: if the
2110 host pattern starts or ends with a dot, it becomes unanchored at that end.
2111 The host pattern is often referred to as domain pattern as it is usually
2112 used to match domain names and not IP addresses.
2118 <term><literal>.example.com</literal></term>
2121 matches any domain with first-level domain <literal>com</literal>
2122 and second-level domain <literal>example</literal>.
2123 For example <literal>www.example.com</literal>,
2124 <literal>example.com</literal> and <literal>foo.bar.baz.example.com</literal>.
2125 Note that it wouldn't match if the second-level domain was <literal>another-example</literal>.
2130 <term><literal>www.</literal></term>
2133 matches any domain that <emphasis>STARTS</emphasis> with
2134 <literal>www.</literal> (It also matches the domain
2135 <literal>www</literal> but most of the time that doesn't matter.)
2140 <term><literal>.example.</literal></term>
2143 matches any domain that <emphasis>CONTAINS</emphasis> <literal>.example.</literal>.
2144 And, by the way, also included would be any files or documents that exist
2145 within that domain since no path limitations are specified. (Correctly
2146 speaking: It matches any FQDN that contains <literal>example</literal> as
2147 a domain.) This might be <literal>www.example.com</literal>,
2148 <literal>news.example.de</literal>, or
2149 <literal>www.example.net/cgi/testing.pl</literal> for instance. All these
2157 Additionally, there are wild-cards that you can use in the domain names
2158 themselves. These work similarly to shell globbing type wild-cards:
2159 <quote>*</quote> represents zero or more arbitrary characters (this is
2161 <ulink url="http://en.wikipedia.org/wiki/Regular_expressions"><quote>Regular
2162 Expression</quote></ulink> based syntax of <quote>.*</quote>),
2163 <quote>?</quote> represents any single character (this is equivalent to the
2164 regular expression syntax of a simple <quote>.</quote>), and you can define
2165 <quote>character classes</quote> in square brackets which is similar to
2166 the same regular expression technique. All of this can be freely mixed:
2171 <term><literal>ad*.example.com</literal></term>
2174 matches <quote>adserver.example.com</quote>,
2175 <quote>ads.example.com</quote>, etc but not <quote>sfads.example.com</quote>
2180 <term><literal>*ad*.example.com</literal></term>
2183 matches all of the above, and then some.
2188 <term><literal>.?pix.com</literal></term>
2191 matches <literal>www.ipix.com</literal>,
2192 <literal>pictures.epix.com</literal>, <literal>a.b.c.d.e.upix.com</literal> etc.
2197 <term><literal>www[1-9a-ez].example.c*</literal></term>
2200 matches <literal>www1.example.com</literal>,
2201 <literal>www4.example.cc</literal>, <literal>wwwd.example.cy</literal>,
2202 <literal>wwwz.example.com</literal> etc., but <emphasis>not</emphasis>
2203 <literal>wwww.example.com</literal>.
2210 While flexible, this is not the sophistication of full regular expression based syntax.
2215 <!-- ~ End section ~ -->
2218 <!-- ~~~~~ New section ~~~~~ -->
2219 <sect3><title>The Path Pattern</title>
2222 <application>Privoxy</application> uses <quote>modern</quote> POSIX 1003.2
2223 <ulink url="http://en.wikipedia.org/wiki/Regular_expressions"><quote>Regular
2224 Expressions</quote></ulink> for matching the path portion (after the slash),
2225 and is thus more flexible.
2229 There is an <link linkend="regex">Appendix</link> with a brief quick-start into regular
2230 expressions, you also might want to have a look at your operating system's documentation
2231 on regular expressions (try <literal>man re_format</literal>).
2235 Note that the path pattern is automatically left-anchored at the <quote>/</quote>,
2236 i.e. it matches as if it would start with a <quote>^</quote> (regular expression speak
2237 for the beginning of a line).
2241 Please also note that matching in the path is <emphasis>CASE INSENSITIVE</emphasis>
2242 by default, but you can switch to case sensitive at any point in the pattern by using the
2243 <quote>(?-i)</quote> switch: <literal>www.example.com/(?-i)PaTtErN.*</literal> will match
2244 only documents whose path starts with <literal>PaTtErN</literal> in
2245 <emphasis>exactly</emphasis> this capitalization.
2250 <term><literal>.example.com/.*</literal></term>
2253 Is equivalent to just <quote>.example.com</quote>, since any documents
2254 within that domain are matched with or without the <quote>.*</quote>
2255 regular expression. This is redundant
2260 <term><literal>.example.com/.*/index.html$</literal></term>
2263 Will match any page in the domain of <quote>example.com</quote> that is
2264 named <quote>index.html</quote>, and that is part of some path. For
2265 example, it matches <quote>www.example.com/testing/index.html</quote> but
2266 NOT <quote>www.example.com/index.html</quote> because the regular
2267 expression called for at least two <quote>/'s</quote>, thus the path
2268 requirement. It also would match
2269 <quote>www.example.com/testing/index_html</quote>, because of the
2270 special meta-character <quote>.</quote>.
2275 <term><literal>.example.com/(.*/)?index\.html$</literal></term>
2278 This regular expression is conditional so it will match any page
2279 named <quote>index.html</quote> regardless of path which in this case can
2280 have one or more <quote>/'s</quote>. And this one must contain exactly
2281 <quote>.html</quote> (but does not have to end with that!).
2286 <term><literal>.example.com/(.*/)(ads|banners?|junk)</literal></term>
2289 This regular expression will match any path of <quote>example.com</quote>
2290 that contains any of the words <quote>ads</quote>, <quote>banner</quote>,
2291 <quote>banners</quote> (because of the <quote>?</quote>) or <quote>junk</quote>.
2292 The path does not have to end in these words, just contain them.
2297 <term><literal>.example.com/(.*/)(ads|banners?|junk)/.*\.(jpe?g|gif|png)$</literal></term>
2300 This is very much the same as above, except now it must end in either
2301 <quote>.jpg</quote>, <quote>.jpeg</quote>, <quote>.gif</quote> or <quote>.png</quote>. So this
2302 one is limited to common image formats.
2309 There are many, many good examples to be found in <filename>default.action</filename>,
2310 and more tutorials below in <link linkend="regex">Appendix on regular expressions</link>.
2315 <!-- ~ End section ~ -->
2318 <!-- ~~~~~ New section ~~~~~ -->
2319 <sect3 id="tag-pattern"><title>The Tag Pattern</title>
2322 Tag patterns are used to change the applying actions based on the
2323 request's tags. Tags can be created with either the
2324 <link linkend="CLIENT-HEADER-TAGGER">client-header-tagger</link>
2325 or the <link linkend="SERVER-HEADER-TAGGER">server-header-tagger</link> action.
2329 Tag patterns have to start with <quote>TAG:</quote>, so &my-app;
2330 can tell them apart from URL patterns. Everything after the colon
2331 including white space, is interpreted as a regular expression with
2332 path pattern syntax, except that tag patterns aren't left-anchored
2333 automatically (&my-app; doesn't silently add a <quote>^</quote>,
2334 you have to do it yourself if you need it).
2338 To match all requests that are tagged with <quote>foo</quote>
2339 your pattern line should be <quote>TAG:^foo$</quote>,
2340 <quote>TAG:foo</quote> would work as well, but it would also
2341 match requests whose tags contain <quote>foo</quote> somewhere.
2342 <quote>TAG: foo</quote> wouldn't work as it requires white space.
2346 Sections can contain URL and tag patterns at the same time,
2347 but tag patterns are checked after the URL patterns and thus
2348 always overrule them, even if they are located before the URL patterns.
2352 Once a new tag is added, Privoxy checks right away if it's matched by one
2353 of the tag patterns and updates the action settings accordingly. As a result
2354 tags can be used to activate other tagger actions, as long as these other
2355 taggers look for headers that haven't already be parsed.
2359 For example you could tag client requests which use the
2360 <literal>POST</literal> method,
2361 then use this tag to activate another tagger that adds a tag if cookies
2362 are sent, and then use a block action based on the cookie tag. This allows
2363 the outcome of one action, to be input into a subsequent action. However if
2364 you'd reverse the position of the described taggers, and activated the
2365 method tagger based on the cookie tagger, no method tags would be created.
2366 The method tagger would look for the request line, but at the time
2367 the cookie tag is created, the request line has already been parsed.
2371 While this is a limitation you should be aware of, this kind of
2372 indirection is seldom needed anyway and even the example doesn't
2373 make too much sense.
2378 <!-- ~~~~~ New section ~~~~~ -->
2379 <sect3 id="negative-tag-patterns"><title>The Negative Tag Patterns</title>
2382 To match requests that do not have a certain tag, specify a negative tag pattern
2383 by prefixing the tag pattern line with either <quote>NO-REQUEST-TAG:</quote>
2384 or <quote>NO-RESPONSE-TAG:</quote> instead of <quote>TAG:</quote>.
2388 Negative tag patterns created with <quote>NO-REQUEST-TAG:</quote> are checked
2389 after all client headers are scanned, the ones created with <quote>NO-RESPONSE-TAG:</quote>
2390 are checked after all server headers are scanned. In both cases all the created
2391 tags are considered.
2397 <!-- ~ End section ~ -->
2400 <!-- ~~~~~ New section ~~~~~ -->
2402 <sect2 id="actions">
2403 <title>Actions</title>
2405 All actions are disabled by default, until they are explicitly enabled
2406 somewhere in an actions file. Actions are turned on if preceded with a
2407 <quote>+</quote>, and turned off if preceded with a <quote>-</quote>. So a
2408 <literal>+action</literal> means <quote>do that action</quote>, e.g.
2409 <literal>+block</literal> means <quote>please block URLs that match the
2410 following patterns</quote>, and <literal>-block</literal> means <quote>don't
2411 block URLs that match the following patterns, even if <literal>+block</literal>
2412 previously applied.</quote>
2417 Again, actions are invoked by placing them on a line, enclosed in curly braces and
2418 separated by whitespace, like in
2419 <literal>{+some-action -some-other-action{some-parameter}}</literal>,
2420 followed by a list of URL patterns, one per line, to which they apply.
2421 Together, the actions line and the following pattern lines make up a section
2422 of the actions file.
2426 Actions fall into three categories:
2433 Boolean, i.e the action can only be <quote>enabled</quote> or
2434 <quote>disabled</quote>. Syntax:
2438 +<replaceable class="function">name</replaceable> # enable action <replaceable class="parameter">name</replaceable>
2439 -<replaceable class="function">name</replaceable> # disable action <replaceable class="parameter">name</replaceable></screen>
2442 Example: <literal>+handle-as-image</literal>
2449 Parameterized, where some value is required in order to enable this type of action.
2454 +<replaceable class="function">name</replaceable>{<replaceable class="parameter">param</replaceable>} # enable action and set parameter to <replaceable class="parameter">param</replaceable>,
2455 # overwriting parameter from previous match if necessary
2456 -<replaceable class="function">name</replaceable> # disable action. The parameter can be omitted</screen>
2459 Note that if the URL matches multiple positive forms of a parameterized action,
2460 the last match wins, i.e. the params from earlier matches are simply ignored.
2463 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>
2469 Multi-value. These look exactly like parameterized actions,
2470 but they behave differently: If the action applies multiple times to the
2471 same URL, but with different parameters, <emphasis>all</emphasis> the parameters
2472 from <emphasis>all</emphasis> matches are remembered. This is used for actions
2473 that can be executed for the same request repeatedly, like adding multiple
2474 headers, or filtering through multiple filters. Syntax:
2478 +<replaceable class="function">name</replaceable>{<replaceable class="parameter">param</replaceable>} # enable action and add <replaceable class="parameter">param</replaceable> to the list of parameters
2479 -<replaceable class="function">name</replaceable>{<replaceable class="parameter">param</replaceable>} # remove the parameter <replaceable class="parameter">param</replaceable> from the list of parameters
2480 # If it was the last one left, disable the action.
2481 <replaceable class="parameter">-name</replaceable> # disable this action completely and remove all parameters from the list</screen>
2484 Examples: <literal>+add-header{X-Fun-Header: Some text}</literal> and
2485 <literal>+filter{html-annoyances}</literal>
2493 If nothing is specified in any actions file, no <quote>actions</quote> are
2494 taken. So in this case <application>Privoxy</application> would just be a
2495 normal, non-blocking, non-filtering proxy. You must specifically enable the
2496 privacy and blocking features you need (although the provided default actions
2497 files will give a good starting point).
2501 Later defined action sections always over-ride earlier ones of the same type.
2502 So exceptions to any rules you make, should come in the latter part of the file (or
2503 in a file that is processed later when using multiple actions files such
2504 as <filename>user.action</filename>). For multi-valued actions, the actions
2505 are applied in the order they are specified. Actions files are processed in
2506 the order they are defined in <filename>config</filename> (the default
2507 installation has three actions files). It also quite possible for any given
2508 URL to match more than one <quote>pattern</quote> (because of wildcards and
2509 regular expressions), and thus to trigger more than one set of actions! Last
2513 <!-- start actions listing -->
2515 The list of valid <application>Privoxy</application> actions are:
2519 <!-- ********************************************************** -->
2520 <!-- Please note the below defined actions use id's that are -->
2521 <!-- probably linked from other places, so please don't change. -->
2523 <!-- ********************************************************** -->
2526 <!-- ~~~~~ New section ~~~~~ -->
2528 <sect3 renderas="sect4" id="add-header">
2529 <title>add-header</title>
2533 <term>Typical use:</term>
2535 <para>Confuse log analysis, custom applications</para>
2540 <term>Effect:</term>
2543 Sends a user defined HTTP header to the web server.
2550 <!-- boolean, parameterized, Multi-value -->
2552 <para>Multi-value.</para>
2557 <term>Parameter:</term>
2560 Any string value is possible. Validity of the defined HTTP headers is not checked.
2561 It is recommended that you use the <quote><literal>X-</literal></quote> prefix
2571 This action may be specified multiple times, in order to define multiple
2572 headers. This is rarely needed for the typical user. If you don't know what
2573 <quote>HTTP headers</quote> are, you definitely don't need to worry about this
2577 Headers added by this action are not modified by other actions.
2583 <term>Example usage:</term>
2586 <screen>+add-header{X-User-Tracking: sucks}</screen>
2594 <!-- ~~~~~ New section ~~~~~ -->
2595 <sect3 renderas="sect4" id="block">
2596 <title>block</title>
2600 <term>Typical use:</term>
2602 <para>Block ads or other unwanted content</para>
2607 <term>Effect:</term>
2610 Requests for URLs to which this action applies are blocked, i.e. the
2611 requests are trapped by &my-app; and the requested URL is never retrieved,
2612 but is answered locally with a substitute page or image, as determined by
2614 linkend="handle-as-image">handle-as-image</link></literal>,
2616 linkend="set-image-blocker">set-image-blocker</link></literal>, and
2618 linkend="handle-as-empty-document">handle-as-empty-document</link></literal> actions.
2626 <!-- boolean, parameterized, Multi-value -->
2628 <para>Parameterized.</para>
2633 <term>Parameter:</term>
2635 <para>A block reason that should be given to the user.</para>
2643 <application>Privoxy</application> sends a special <quote>BLOCKED</quote> page
2644 for requests to blocked pages. This page contains the block reason given as
2645 parameter, a link to find out why the block action applies, and a click-through
2646 to the blocked content (the latter only if the force feature is available and
2650 A very important exception occurs if <emphasis>both</emphasis>
2651 <literal>block</literal> and <literal><link linkend="handle-as-image">handle-as-image</link></literal>,
2652 apply to the same request: it will then be replaced by an image. If
2653 <literal><link linkend="set-image-blocker">set-image-blocker</link></literal>
2654 (see below) also applies, the type of image will be determined by its parameter,
2655 if not, the standard checkerboard pattern is sent.
2658 It is important to understand this process, in order
2659 to understand how <application>Privoxy</application> deals with
2660 ads and other unwanted content. Blocking is a core feature, and one
2661 upon which various other features depend.
2664 The <literal><link linkend="filter">filter</link></literal>
2665 action can perform a very similar task, by <quote>blocking</quote>
2666 banner images and other content through rewriting the relevant URLs in the
2667 document's HTML source, so they don't get requested in the first place.
2668 Note that this is a totally different technique, and it's easy to confuse the two.
2674 <term>Example usage (section):</term>
2677 <screen>{+block{No nasty stuff for you.}}
2678 # Block and replace with "blocked" page
2679 .nasty-stuff.example.com
2681 {+block{Doubleclick banners.} +handle-as-image}
2682 # Block and replace with image
2686 {+block{Layered ads.} +handle-as-empty-document}
2687 # Block and then ignore
2688 adserver.example.net/.*\.js$</screen>
2698 <!-- ~~~~~ New section ~~~~~ -->
2699 <sect3 renderas="sect4" id="change-x-forwarded-for">
2700 <title>change-x-forwarded-for</title>
2704 <term>Typical use:</term>
2706 <para>Improve privacy by not forwarding the source of the request in the HTTP headers.</para>
2711 <term>Effect:</term>
2714 Deletes the <quote>X-Forwarded-For:</quote> HTTP header from the client request,
2722 <!-- Boolean, Parameterized, Multi-value -->
2724 <para>Parameterized.</para>
2729 <term>Parameter:</term>
2733 <para><quote>block</quote> to delete the header.</para>
2737 <quote>add</quote> to create the header (or append
2738 the client's IP address to an already existing one).
2749 It is safe and recommended to use <literal>block</literal>.
2752 Forwarding the source address of the request may make
2753 sense in some multi-user setups but is also a privacy risk.
2758 <term>Example usage:</term>
2761 <screen>+change-x-forwarded-for{block}</screen>
2768 <!-- ~~~~~ New section ~~~~~ -->
2769 <sect3 renderas="sect4" id="client-header-filter">
2770 <title>client-header-filter</title>
2774 <term>Typical use:</term>
2777 Rewrite or remove single client headers.
2783 <term>Effect:</term>
2786 All client headers to which this action applies are filtered on-the-fly through
2787 the specified regular expression based substitutions.
2794 <!-- boolean, parameterized, Multi-value -->
2796 <para>Parameterized.</para>
2801 <term>Parameter:</term>
2804 The name of a client-header filter, as defined in one of the
2805 <link linkend="filter-file">filter files</link>.
2814 Client-header filters are applied to each header on its own, not to
2815 all at once. This makes it easier to diagnose problems, but on the downside
2816 you can't write filters that only change header x if header y's value is z.
2817 You can do that by using tags though.
2820 Client-header filters are executed after the other header actions have finished
2821 and use their output as input.
2824 If the request URI gets changed, &my-app; will detect that and use the new
2825 one. This can be used to rewrite the request destination behind the client's
2826 back, for example to specify a Tor exit relay for certain requests.
2829 Please refer to the <link linkend="filter-file">filter file chapter</link>
2830 to learn which client-header filters are available by default, and how to
2838 <term>Example usage (section):</term>
2842 # Hide Tor exit notation in Host and Referer Headers
2843 {+client-header-filter{hide-tor-exit-notation}}
2854 <!-- ~~~~~ New section ~~~~~ -->
2855 <sect3 renderas="sect4" id="client-header-tagger">
2856 <title>client-header-tagger</title>
2860 <term>Typical use:</term>
2863 Block requests based on their headers.
2869 <term>Effect:</term>
2872 Client headers to which this action applies are filtered on-the-fly through
2873 the specified regular expression based substitutions, the result is used as
2881 <!-- boolean, parameterized, Multi-value -->
2883 <para>Parameterized.</para>
2888 <term>Parameter:</term>
2891 The name of a client-header tagger, as defined in one of the
2892 <link linkend="filter-file">filter files</link>.
2901 Client-header taggers are applied to each header on its own,
2902 and as the header isn't modified, each tagger <quote>sees</quote>
2906 Client-header taggers are the first actions that are executed
2907 and their tags can be used to control every other action.
2913 <term>Example usage (section):</term>
2917 # Tag every request with the User-Agent header
2918 {+client-header-tagger{user-agent}}
2921 # Tagging itself doesn't change the action
2922 # settings, sections with TAG patterns do:
2924 # If it's a download agent, use a different forwarding proxy,
2925 # show the real User-Agent and make sure resume works.
2926 {+forward-override{forward-socks5 10.0.0.2:2222 .} \
2927 -hide-if-modified-since \
2928 -overwrite-last-modified \
2933 TAG:^User-Agent: NetBSD-ftp/
2934 TAG:^User-Agent: Novell ZYPP Installer
2935 TAG:^User-Agent: RPM APT-HTTP/
2936 TAG:^User-Agent: fetch libfetch/
2937 TAG:^User-Agent: Ubuntu APT-HTTP/
2938 TAG:^User-Agent: MPlayer/
2943 # Tag all requests with the Range header set
2944 {+client-header-tagger{range-requests}}
2947 # Disable filtering for the tagged requests.
2949 # With filtering enabled Privoxy would remove the Range headers
2950 # to be able to filter the whole response. The downside is that
2951 # it prevents clients from resuming downloads or skipping over
2952 # parts of multimedia files.
2953 {-filter -deanimate-gifs}
2964 <!-- ~~~~~ New section ~~~~~ -->
2965 <sect3 renderas="sect4" id="content-type-overwrite">
2966 <title>content-type-overwrite</title>
2970 <term>Typical use:</term>
2972 <para>Stop useless download menus from popping up, or change the browser's rendering mode</para>
2977 <term>Effect:</term>
2980 Replaces the <quote>Content-Type:</quote> HTTP server header.
2987 <!-- Boolean, Parameterized, Multi-value -->
2989 <para>Parameterized.</para>
2994 <term>Parameter:</term>
3006 The <quote>Content-Type:</quote> HTTP server header is used by the
3007 browser to decide what to do with the document. The value of this
3008 header can cause the browser to open a download menu instead of
3009 displaying the document by itself, even if the document's format is
3010 supported by the browser.
3013 The declared content type can also affect which rendering mode
3014 the browser chooses. If XHTML is delivered as <quote>text/html</quote>,
3015 many browsers treat it as yet another broken HTML document.
3016 If it is send as <quote>application/xml</quote>, browsers with
3017 XHTML support will only display it, if the syntax is correct.
3020 If you see a web site that proudly uses XHTML buttons, but sets
3021 <quote>Content-Type: text/html</quote>, you can use &my-app;
3022 to overwrite it with <quote>application/xml</quote> and validate
3023 the web master's claim inside your XHTML-supporting browser.
3024 If the syntax is incorrect, the browser will complain loudly.
3027 You can also go the opposite direction: if your browser prints
3028 error messages instead of rendering a document falsely declared
3029 as XHTML, you can overwrite the content type with
3030 <quote>text/html</quote> and have it rendered as broken HTML document.
3033 By default <literal>content-type-overwrite</literal> only replaces
3034 <quote>Content-Type:</quote> headers that look like some kind of text.
3035 If you want to overwrite it unconditionally, you have to combine it with
3036 <literal><link linkend="force-text-mode">force-text-mode</link></literal>.
3037 This limitation exists for a reason, think twice before circumventing it.
3040 Most of the time it's easier to replace this action with a custom
3041 <literal><link linkend="server-header-filter">server-header filter</link></literal>.
3042 It allows you to activate it for every document of a certain site and it will still
3043 only replace the content types you aimed at.
3046 Of course you can apply <literal>content-type-overwrite</literal>
3047 to a whole site and then make URL based exceptions, but it's a lot
3048 more work to get the same precision.
3054 <term>Example usage (sections):</term>
3057 <screen># Check if www.example.net/ really uses valid XHTML
3058 { +content-type-overwrite{application/xml} }
3061 # but leave the content type unmodified if the URL looks like a style sheet
3062 {-content-type-overwrite}
3063 www.example.net/.*\.css$
3064 www.example.net/.*style
3073 <!-- ~~~~~ New section ~~~~~ -->
3074 <sect3 renderas="sect4" id="crunch-client-header">
3078 <title>crunch-client-header</title>
3082 <term>Typical use:</term>
3084 <para>Remove a client header <application>Privoxy</application> has no dedicated action for.</para>
3089 <term>Effect:</term>
3092 Deletes every header sent by the client that contains the string the user supplied as parameter.
3099 <!-- Boolean, Parameterized, Multi-value -->
3101 <para>Parameterized.</para>
3106 <term>Parameter:</term>
3118 This action allows you to block client headers for which no dedicated
3119 <application>Privoxy</application> action exists.
3120 <application>Privoxy</application> will remove every client header that
3121 contains the string you supplied as parameter.
3124 Regular expressions are <emphasis>not supported</emphasis> and you can't
3125 use this action to block different headers in the same request, unless
3126 they contain the same string.
3129 <literal>crunch-client-header</literal> is only meant for quick tests.
3130 If you have to block several different headers, or only want to modify
3131 parts of them, you should use a
3132 <literal><link linkend="client-header-filter">client-header filter</link></literal>.
3136 Don't block any header without understanding the consequences.
3143 <term>Example usage (section):</term>
3146 <screen># Block the non-existent "Privacy-Violation:" client header
3147 { +crunch-client-header{Privacy-Violation:} }
3157 <!-- ~~~~~ New section ~~~~~ -->
3158 <sect3 renderas="sect4" id="crunch-if-none-match">
3159 <title>crunch-if-none-match</title>
3165 <term>Typical use:</term>
3167 <para>Prevent yet another way to track the user's steps between sessions.</para>
3172 <term>Effect:</term>
3175 Deletes the <quote>If-None-Match:</quote> HTTP client header.
3182 <!-- Boolean, Parameterized, Multi-value -->
3184 <para>Boolean.</para>
3189 <term>Parameter:</term>
3201 Removing the <quote>If-None-Match:</quote> HTTP client header
3202 is useful for filter testing, where you want to force a real
3203 reload instead of getting status code <quote>304</quote> which
3204 would cause the browser to use a cached copy of the page.
3207 It is also useful to make sure the header isn't used as a cookie
3208 replacement (unlikely but possible).
3211 Blocking the <quote>If-None-Match:</quote> header shouldn't cause any
3212 caching problems, as long as the <quote>If-Modified-Since:</quote> header
3213 isn't blocked or missing as well.
3216 It is recommended to use this action together with
3217 <literal><link linkend="hide-if-modified-since">hide-if-modified-since</link></literal>
3219 <literal><link linkend="overwrite-last-modified">overwrite-last-modified</link></literal>.
3225 <term>Example usage (section):</term>
3228 <screen># Let the browser revalidate cached documents but don't
3229 # allow the server to use the revalidation headers for user tracking.
3230 {+hide-if-modified-since{-60} \
3231 +overwrite-last-modified{randomize} \
3232 +crunch-if-none-match}
3241 <!-- ~~~~~ New section ~~~~~ -->
3242 <sect3 renderas="sect4" id="crunch-incoming-cookies">
3243 <title>crunch-incoming-cookies</title>
3247 <term>Typical use:</term>
3250 Prevent the web server from setting HTTP cookies on your system
3256 <term>Effect:</term>
3259 Deletes any <quote>Set-Cookie:</quote> HTTP headers from server replies.
3266 <!-- Boolean, Parameterized, Multi-value -->
3268 <para>Boolean.</para>
3273 <term>Parameter:</term>
3285 This action is only concerned with <emphasis>incoming</emphasis> HTTP cookies. For
3286 <emphasis>outgoing</emphasis> HTTP cookies, use
3287 <literal><link linkend="crunch-outgoing-cookies">crunch-outgoing-cookies</link></literal>.
3288 Use <emphasis>both</emphasis> to disable HTTP cookies completely.
3291 It makes <emphasis>no sense at all</emphasis> to use this action in conjunction
3292 with the <literal><link linkend="session-cookies-only">session-cookies-only</link></literal> action,
3293 since it would prevent the session cookies from being set. See also
3294 <literal><link linkend="filter-content-cookies">filter-content-cookies</link></literal>.
3300 <term>Example usage:</term>
3303 <screen>+crunch-incoming-cookies</screen>
3311 <!-- ~~~~~ New section ~~~~~ -->
3312 <sect3 renderas="sect4" id="crunch-server-header">
3313 <title>crunch-server-header</title>
3319 <term>Typical use:</term>
3321 <para>Remove a server header <application>Privoxy</application> has no dedicated action for.</para>
3326 <term>Effect:</term>
3329 Deletes every header sent by the server that contains the string the user supplied as parameter.
3336 <!-- Boolean, Parameterized, Multi-value -->
3338 <para>Parameterized.</para>
3343 <term>Parameter:</term>
3355 This action allows you to block server headers for which no dedicated
3356 <application>Privoxy</application> action exists. <application>Privoxy</application>
3357 will remove every server header that contains the string you supplied as parameter.
3360 Regular expressions are <emphasis>not supported</emphasis> and you can't
3361 use this action to block different headers in the same request, unless
3362 they contain the same string.
3365 <literal>crunch-server-header</literal> is only meant for quick tests.
3366 If you have to block several different headers, or only want to modify
3367 parts of them, you should use a custom
3368 <literal><link linkend="server-header-filter">server-header filter</link></literal>.
3372 Don't block any header without understanding the consequences.
3379 <term>Example usage (section):</term>
3382 <screen># Crunch server headers that try to prevent caching
3383 { +crunch-server-header{no-cache} }
3392 <!-- ~~~~~ New section ~~~~~ -->
3393 <sect3 renderas="sect4" id="crunch-outgoing-cookies">
3394 <title>crunch-outgoing-cookies</title>
3398 <term>Typical use:</term>
3401 Prevent the web server from reading any HTTP cookies from your system
3407 <term>Effect:</term>
3410 Deletes any <quote>Cookie:</quote> HTTP headers from client requests.
3417 <!-- Boolean, Parameterized, Multi-value -->
3419 <para>Boolean.</para>
3424 <term>Parameter:</term>
3436 This action is only concerned with <emphasis>outgoing</emphasis> HTTP cookies. For
3437 <emphasis>incoming</emphasis> HTTP cookies, use
3438 <literal><link linkend="crunch-incoming-cookies">crunch-incoming-cookies</link></literal>.
3439 Use <emphasis>both</emphasis> to disable HTTP cookies completely.
3442 It makes <emphasis>no sense at all</emphasis> to use this action in conjunction
3443 with the <literal><link linkend="session-cookies-only">session-cookies-only</link></literal> action,
3444 since it would prevent the session cookies from being read.
3450 <term>Example usage:</term>
3453 <screen>+crunch-outgoing-cookies</screen>
3462 <!-- ~~~~~ New section ~~~~~ -->
3463 <sect3 renderas="sect4" id="deanimate-gifs">
3464 <title>deanimate-gifs</title>
3468 <term>Typical use:</term>
3470 <para>Stop those annoying, distracting animated GIF images.</para>
3475 <term>Effect:</term>
3478 De-animate GIF animations, i.e. reduce them to their first or last image.
3485 <!-- boolean, parameterized, Multi-value -->
3487 <para>Parameterized.</para>
3492 <term>Parameter:</term>
3495 <quote>last</quote> or <quote>first</quote>
3504 This will also shrink the images considerably (in bytes, not pixels!). If
3505 the option <quote>first</quote> is given, the first frame of the animation
3506 is used as the replacement. If <quote>last</quote> is given, the last
3507 frame of the animation is used instead, which probably makes more sense for
3508 most banner animations, but also has the risk of not showing the entire
3509 last frame (if it is only a delta to an earlier frame).
3512 You can safely use this action with patterns that will also match non-GIF
3513 objects, because no attempt will be made at anything that doesn't look like
3520 <term>Example usage:</term>
3523 <screen>+deanimate-gifs{last}</screen>
3530 <!-- ~~~~~ New section ~~~~~ -->
3531 <sect3 renderas="sect4" id="downgrade-http-version">
3532 <title>downgrade-http-version</title>
3536 <term>Typical use:</term>
3538 <para>Work around (very rare) problems with HTTP/1.1</para>
3543 <term>Effect:</term>
3546 Downgrades HTTP/1.1 client requests and server replies to HTTP/1.0.
3553 <!-- boolean, parameterized, Multi-value -->
3555 <para>Boolean.</para>
3560 <term>Parameter:</term>
3572 This is a left-over from the time when <application>Privoxy</application>
3573 didn't support important HTTP/1.1 features well. It is left here for the
3574 unlikely case that you experience HTTP/1.1-related problems with some server
3578 Note that enabling this action is only a workaround. It should not
3579 be enabled for sites that work without it. While it shouldn't break
3580 any pages, it has an (usually negative) performance impact.
3583 If you come across a site where enabling this action helps, please report it,
3584 so the cause of the problem can be analyzed. If the problem turns out to be
3585 caused by a bug in <application>Privoxy</application> it should be
3586 fixed so the following release works without the work around.
3592 <term>Example usage (section):</term>
3595 <screen>{+downgrade-http-version}
3596 problem-host.example.com</screen>
3604 <!-- ~~~~~ New section ~~~~~ -->
3605 <sect3 renderas="sect4" id="fast-redirects">
3606 <title>fast-redirects</title>
3610 <term>Typical use:</term>
3612 <para>Fool some click-tracking scripts and speed up indirect links.</para>
3617 <term>Effect:</term>
3620 Detects redirection URLs and redirects the browser without contacting
3621 the redirection server first.
3628 <!-- boolean, parameterized, Multi-value -->
3630 <para>Parameterized.</para>
3635 <term>Parameter:</term>
3640 <quote>simple-check</quote> to just search for the string <quote>http://</quote>
3641 to detect redirection URLs.
3646 <quote>check-decoded-url</quote> to decode URLs (if necessary) before searching
3647 for redirection URLs.
3658 Many sites, like yahoo.com, don't just link to other sites. Instead, they
3659 will link to some script on their own servers, giving the destination as a
3660 parameter, which will then redirect you to the final target. URLs
3661 resulting from this scheme typically look like:
3662 <quote>http://www.example.org/click-tracker.cgi?target=http%3a//www.example.net/</quote>.
3665 Sometimes, there are even multiple consecutive redirects encoded in the
3666 URL. These redirections via scripts make your web browsing more traceable,
3667 since the server from which you follow such a link can see where you go
3668 to. Apart from that, valuable bandwidth and time is wasted, while your
3669 browser asks the server for one redirect after the other. Plus, it feeds
3673 This feature is currently not very smart and is scheduled for improvement.
3674 If it is enabled by default, you will have to create some exceptions to
3675 this action. It can lead to failures in several ways:
3678 Not every URLs with other URLs as parameters is evil.
3679 Some sites offer a real service that requires this information to work.
3680 For example a validation service needs to know, which document to validate.
3681 <literal>fast-redirects</literal> assumes that every URL parameter that
3682 looks like another URL is a redirection target, and will always redirect to
3683 the last one. Most of the time the assumption is correct, but if it isn't,
3684 the user gets redirected anyway.
3687 Another failure occurs if the URL contains other parameters after the URL parameter.
3689 <quote>http://www.example.org/?redirect=http%3a//www.example.net/&foo=bar</quote>.
3690 contains the redirection URL <quote>http://www.example.net/</quote>,
3691 followed by another parameter. <literal>fast-redirects</literal> doesn't know that
3692 and will cause a redirect to <quote>http://www.example.net/&foo=bar</quote>.
3693 Depending on the target server configuration, the parameter will be silently ignored
3694 or lead to a <quote>page not found</quote> error. You can prevent this problem by
3695 first using the <literal><link linkend="redirect">redirect</link></literal> action
3696 to remove the last part of the URL, but it requires a little effort.
3699 To detect a redirection URL, <literal>fast-redirects</literal> only
3700 looks for the string <quote>http://</quote>, either in plain text
3701 (invalid but often used) or encoded as <quote>http%3a//</quote>.
3702 Some sites use their own URL encoding scheme, encrypt the address
3703 of the target server or replace it with a database id. In theses cases
3704 <literal>fast-redirects</literal> is fooled and the request reaches the
3705 redirection server where it probably gets logged.
3711 <term>Example usage:</term>
3715 { +fast-redirects{simple-check} }
3718 { +fast-redirects{check-decoded-url} }
3719 another.example.com/testing</screen>
3728 <!-- ~~~~~ New section ~~~~~ -->
3729 <sect3 renderas="sect4" id="filter">
3730 <title>filter</title>
3734 <term>Typical use:</term>
3736 <para>Get rid of HTML and JavaScript annoyances, banner advertisements (by size),
3737 do fun text replacements, add personalized effects, etc.</para>
3742 <term>Effect:</term>
3745 All instances of text-based type, most notably HTML and JavaScript, to which
3746 this action applies, can be filtered on-the-fly through the specified regular
3747 expression based substitutions. (Note: as of version 3.0.3 plain text documents
3748 are exempted from filtering, because web servers often use the
3749 <literal>text/plain</literal> MIME type for all files whose type they don't know.)
3756 <!-- boolean, parameterized, Multi-value -->
3758 <para>Parameterized.</para>
3763 <term>Parameter:</term>
3766 The name of a content filter, as defined in the <link linkend="filter-file">filter file</link>.
3767 Filters can be defined in one or more files as defined by the
3768 <literal><link linkend="filterfile">filterfile</link></literal>
3769 option in the <link linkend="config">config file</link>.
3770 <filename>default.filter</filename> is the collection of filters
3771 supplied by the developers. Locally defined filters should go
3772 in their own file, such as <filename>user.filter</filename>.
3775 When used in its negative form,
3776 and without parameters, <emphasis>all</emphasis> filtering is completely disabled.
3785 For your convenience, there are a number of pre-defined filters available
3786 in the distribution filter file that you can use. See the examples below for
3790 Filtering requires buffering the page content, which may appear to
3791 slow down page rendering since nothing is displayed until all content has
3792 passed the filters. (The total time until the page is completely rendered
3793 doesn't change much, but it may be perceived as slower since the page is
3794 not incrementally displayed.)
3795 This effect will be more noticeable on slower connections.
3798 <quote>Rolling your own</quote>
3799 filters requires a knowledge of
3800 <ulink url="http://en.wikipedia.org/wiki/Regular_expressions"><quote>Regular
3801 Expressions</quote></ulink> and
3802 <ulink url="http://en.wikipedia.org/wiki/Html"><quote>HTML</quote></ulink>.
3803 This is very powerful feature, and potentially very intrusive.
3804 Filters should be used with caution, and where an equivalent
3805 <quote>action</quote> is not available.
3808 The amount of data that can be filtered is limited to the
3809 <literal><link linkend="buffer-limit">buffer-limit</link></literal>
3810 option in the main <link linkend="config">config file</link>. The
3811 default is 4096 KB (4 Megs). Once this limit is exceeded, the buffered
3812 data, and all pending data, is passed through unfiltered.
3815 Inappropriate MIME types, such as zipped files, are not filtered at all.
3816 (Again, only text-based types except plain text). Encrypted SSL data
3817 (from HTTPS servers) cannot be filtered either, since this would violate
3818 the integrity of the secure transaction. In some situations it might
3819 be necessary to protect certain text, like source code, from filtering
3820 by defining appropriate <literal>-filter</literal> exceptions.
3823 Compressed content can't be filtered either, but if &my-app;
3824 is compiled with zlib support and a supported compression algorithm
3825 is used (gzip or deflate), &my-app; can first decompress the content
3829 If you use a &my-app; version without zlib support, but want filtering to work on
3830 as much documents as possible, even those that would normally be sent compressed,
3831 you must use the <literal><link linkend="prevent-compression">prevent-compression</link></literal>
3832 action in conjunction with <literal>filter</literal>.
3835 Content filtering can achieve some of the same effects as the
3836 <literal><link linkend="block">block</link></literal>
3837 action, i.e. it can be used to block ads and banners. But the mechanism
3838 works quite differently. One effective use, is to block ad banners
3839 based on their size (see below), since many of these seem to be somewhat
3843 <link linkend="contact">Feedback</link> with suggestions for new or
3844 improved filters is particularly welcome!
3847 The below list has only the names and a one-line description of each
3848 predefined filter. There are <link linkend="predefined-filters">more
3849 verbose explanations</link> of what these filters do in the <link
3850 linkend="filter-file">filter file chapter</link>.
3856 <term>Example usage (with filters from the distribution <filename>default.filter</filename> file).
3857 See <link linkend="PREDEFINED-FILTERS">the Predefined Filters section</link> for
3858 more explanation on each:</term>
3861 <anchor id="filter-js-annoyances">
3862 <screen>+filter{js-annoyances} # Get rid of particularly annoying JavaScript abuse.</screen>
3865 <anchor id="filter-js-events">
3866 <screen>+filter{js-events} # Kill JavaScript event bindings and timers (Radically destructive! Only for extra nasty sites).</screen>
3869 <anchor id="filter-html-annoyances">
3870 <screen>+filter{html-annoyances} # Get rid of particularly annoying HTML abuse.</screen>
3873 <anchor id="filter-content-cookies">
3874 <screen>+filter{content-cookies} # Kill cookies that come in the HTML or JS content.</screen>
3877 <anchor id="filter-refresh-tags">
3878 <screen>+filter{refresh-tags} # Kill automatic refresh tags if refresh time is larger than 9 seconds.</screen>
3881 <anchor id="filter-unsolicited-popups">
3882 <screen>+filter{unsolicited-popups} # Disable only unsolicited pop-up windows.</screen>
3885 <anchor id="filter-all-popups">
3886 <screen>+filter{all-popups} # Kill all popups in JavaScript and HTML.</screen>
3889 <anchor id="filter-img-reorder">
3890 <screen>+filter{img-reorder} # Reorder attributes in <img> tags to make the banners-by-* filters more effective.</screen>
3893 <anchor id="filter-banners-by-size">
3894 <screen>+filter{banners-by-size} # Kill banners by size.</screen>
3897 <anchor id="filter-banners-by-link">
3898 <screen>+filter{banners-by-link} # Kill banners by their links to known clicktrackers.</screen>
3901 <anchor id="filter-webbugs">
3902 <screen>+filter{webbugs} # Squish WebBugs (1x1 invisible GIFs used for user tracking).</screen>
3905 <anchor id="filter-tiny-textforms">
3906 <screen>+filter{tiny-textforms} # Extend those tiny textareas up to 40x80 and kill the hard wrap.</screen>
3909 <anchor id="filter-jumping-windows">
3910 <screen>+filter{jumping-windows} # Prevent windows from resizing and moving themselves.</screen>
3913 <anchor id="filter-frameset-borders">
3914 <screen>+filter{frameset-borders} # Give frames a border and make them resizable.</screen>
3917 <anchor id="filter-iframes">
3918 <screen>+filter{iframes} # Removes all detected iframes. Should only be enabled for individual sites.</screen>
3921 <anchor id="filter-demoronizer">
3922 <screen>+filter{demoronizer} # Fix MS's non-standard use of standard charsets.</screen>
3925 <anchor id="filter-shockwave-flash">
3926 <screen>+filter{shockwave-flash} # Kill embedded Shockwave Flash objects.</screen>
3929 <anchor id="filter-quicktime-kioskmode">
3930 <screen>+filter{quicktime-kioskmode} # Make Quicktime movies saveable.</screen>
3933 <anchor id="filter-fun">
3934 <screen>+filter{fun} # Text replacements for subversive browsing fun!</screen>
3937 <anchor id="filter-crude-parental">
3938 <screen>+filter{crude-parental} # Crude parental filtering. Note that this filter doesn't work reliably.</screen>
3941 <anchor id="filter-ie-exploits">
3942 <screen>+filter{ie-exploits} # Disable some known Internet Explorer bug exploits.</screen>
3945 <anchor id="filter-site-specifics">
3946 <screen>+filter{site-specifics} # Cure for site-specific problems. Don't apply generally!</screen>
3949 <anchor id="filter-no-ping">
3950 <screen>+filter{no-ping} # Removes non-standard ping attributes in <a> and <area> tags.</screen>
3953 <anchor id="filter-google">
3954 <screen>+filter{google} # CSS-based block for Google text ads. Also removes a width limitation and the toolbar advertisement.</screen>
3957 <anchor id="filter-yahoo">
3958 <screen>+filter{yahoo} # CSS-based block for Yahoo text ads. Also removes a width limitation.</screen>
3961 <anchor id="filter-msn">
3962 <screen>+filter{msn} # CSS-based block for MSN text ads. Also removes tracking URLs and a width limitation.</screen>
3965 <anchor id="filter-blogspot">
3966 <screen>+filter{blogspot} # Cleans up some Blogspot blogs. Read the fine print before using this.</screen>
3974 <!-- ~~~~~ New section ~~~~~ -->
3975 <sect3 renderas="sect4" id="force-text-mode">
3976 <title>force-text-mode</title>
3982 <term>Typical use:</term>
3984 <para>Force <application>Privoxy</application> to treat a document as if it was in some kind of <emphasis>text</emphasis> format. </para>
3989 <term>Effect:</term>
3992 Declares a document as text, even if the <quote>Content-Type:</quote> isn't detected as such.
3999 <!-- Boolean, Parameterized, Multi-value -->
4001 <para>Boolean.</para>
4006 <term>Parameter:</term>
4018 As explained <literal><link linkend="filter">above</link></literal>,
4019 <application>Privoxy</application> tries to only filter files that are
4020 in some kind of text format. The same restrictions apply to
4021 <literal><link linkend="content-type-overwrite">content-type-overwrite</link></literal>.
4022 <literal>force-text-mode</literal> declares a document as text,
4023 without looking at the <quote>Content-Type:</quote> first.
4027 Think twice before activating this action. Filtering binary data
4028 with regular expressions can cause file damage.
4035 <term>Example usage:</term>
4048 <!-- ~~~~~ New section ~~~~~ -->
4049 <sect3 renderas="sect4" id="forward-override">
4050 <title>forward-override</title>
4056 <term>Typical use:</term>
4058 <para>Change the forwarding settings based on User-Agent or request origin</para>
4063 <term>Effect:</term>
4066 Overrules the forward directives in the configuration file.
4073 <!-- Boolean, Parameterized, Multi-value -->
4075 <para>Multi-value.</para>
4080 <term>Parameter:</term>
4084 <para><quote>forward .</quote> to use a direct connection without any additional proxies.</para>
4088 <quote>forward 127.0.0.1:8123</quote> to use the HTTP proxy listening at 127.0.0.1 port 8123.
4093 <quote>forward-socks4a 127.0.0.1:9050 .</quote> to use the socks4a proxy listening at
4094 127.0.0.1 port 9050. Replace <quote>forward-socks4a</quote> with <quote>forward-socks4</quote>
4095 to use a socks4 connection (with local DNS resolution) instead, use <quote>forward-socks5</quote>
4096 for socks5 connections (with remote DNS resolution).
4101 <quote>forward-socks4a 127.0.0.1:9050 proxy.example.org:8000</quote> to use the socks4a proxy
4102 listening at 127.0.0.1 port 9050 to reach the HTTP proxy listening at proxy.example.org port 8000.
4103 Replace <quote>forward-socks4a</quote> with <quote>forward-socks4</quote> to use a socks4 connection
4104 (with local DNS resolution) instead, use <quote>forward-socks5</quote>
4105 for socks5 connections (with remote DNS resolution).
4116 This action takes parameters similar to the
4117 <link linkend="forwarding">forward</link> directives in the configuration
4118 file, but without the URL pattern. It can be used as replacement, but normally it's only
4119 used in cases where matching based on the request URL isn't sufficient.
4123 Please read the description for the <link linkend="forwarding">forward</link> directives before
4124 using this action. Forwarding to the wrong people will reduce your privacy and increase the
4125 chances of man-in-the-middle attacks.
4128 If the ports are missing or invalid, default values will be used. This might change
4129 in the future and you shouldn't rely on it. Otherwise incorrect syntax causes Privoxy
4133 Use the <ulink url="http://config.privoxy.org/show-url-info">show-url-info CGI page</ulink>
4134 to verify that your forward settings do what you thought the do.
4141 <term>Example usage:</term>
4145 # Always use direct connections for requests previously tagged as
4146 # <quote>User-Agent: fetch libfetch/2.0</quote> and make sure
4147 # resuming downloads continues to work.
4148 # This way you can continue to use Tor for your normal browsing,
4149 # without overloading the Tor network with your FreeBSD ports updates
4150 # or downloads of bigger files like ISOs.
4151 # Note that HTTP headers are easy to fake and therefore their
4152 # values are as (un)trustworthy as your clients and users.
4153 {+forward-override{forward .} \
4154 -hide-if-modified-since \
4155 -overwrite-last-modified \
4157 TAG:^User-Agent: fetch libfetch/2\.0$
4166 <!-- ~~~~~ New section ~~~~~ -->
4167 <sect3 renderas="sect4" id="handle-as-empty-document">
4168 <title>handle-as-empty-document</title>
4174 <term>Typical use:</term>
4176 <para>Mark URLs that should be replaced by empty documents <emphasis>if they get blocked</emphasis></para>
4181 <term>Effect:</term>
4184 This action alone doesn't do anything noticeable. It just marks URLs.
4185 If the <literal><link linkend="block">block</link></literal> action <emphasis>also applies</emphasis>,
4186 the presence or absence of this mark decides whether an HTML <quote>BLOCKED</quote>
4187 page, or an empty document will be sent to the client as a substitute for the blocked content.
4188 The <emphasis>empty</emphasis> document isn't literally empty, but actually contains a single space.
4195 <!-- Boolean, Parameterized, Multi-value -->
4197 <para>Boolean.</para>
4202 <term>Parameter:</term>
4214 Some browsers complain about syntax errors if JavaScript documents
4215 are blocked with <application>Privoxy's</application>
4216 default HTML page; this option can be used to silence them.
4217 And of course this action can also be used to eliminate the &my-app;
4218 BLOCKED message in frames.
4221 The content type for the empty document can be specified with
4222 <literal><link linkend="content-type-overwrite">content-type-overwrite{}</link></literal>,
4223 but usually this isn't necessary.
4229 <term>Example usage:</term>
4232 <screen># Block all documents on example.org that end with ".js",
4233 # but send an empty document instead of the usual HTML message.
4234 {+block{Blocked JavaScript} +handle-as-empty-document}
4244 <!-- ~~~~~ New section ~~~~~ -->
4245 <sect3 renderas="sect4" id="handle-as-image">
4246 <title>handle-as-image</title>
4250 <term>Typical use:</term>
4252 <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>
4257 <term>Effect:</term>
4260 This action alone doesn't do anything noticeable. It just marks URLs as images.
4261 If the <literal><link linkend="block">block</link></literal> action <emphasis>also applies</emphasis>,
4262 the presence or absence of this mark decides whether an HTML <quote>blocked</quote>
4263 page, or a replacement image (as determined by the <literal><link
4264 linkend="set-image-blocker">set-image-blocker</link></literal> action) will be sent to the
4265 client as a substitute for the blocked content.
4272 <!-- Boolean, Parameterized, Multi-value -->
4274 <para>Boolean.</para>
4279 <term>Parameter:</term>
4291 The below generic example section is actually part of <filename>default.action</filename>.
4292 It marks all URLs with well-known image file name extensions as images and should
4296 Users will probably only want to use the handle-as-image action in conjunction with
4297 <literal><link linkend="block">block</link></literal>, to block sources of banners, whose URLs don't
4298 reflect the file type, like in the second example section.
4301 Note that you cannot treat HTML pages as images in most cases. For instance, (in-line) ad
4302 frames require an HTML page to be sent, or they won't display properly.
4303 Forcing <literal>handle-as-image</literal> in this situation will not replace the
4304 ad frame with an image, but lead to error messages.
4310 <term>Example usage (sections):</term>
4313 <screen># Generic image extensions:
4316 /.*\.(gif|jpg|jpeg|png|bmp|ico)$
4318 # These don't look like images, but they're banners and should be
4319 # blocked as images:
4321 {+block{Nasty banners.} +handle-as-image}
4322 nasty-banner-server.example.com/junk.cgi\?output=trash
4331 <!-- ~~~~~ New section ~~~~~ -->
4332 <sect3 renderas="sect4" id="hide-accept-language">
4333 <title>hide-accept-language</title>
4339 <term>Typical use:</term>
4341 <para>Pretend to use different language settings.</para>
4346 <term>Effect:</term>
4349 Deletes or replaces the <quote>Accept-Language:</quote> HTTP header in client requests.
4356 <!-- Boolean, Parameterized, Multi-value -->
4358 <para>Parameterized.</para>
4363 <term>Parameter:</term>
4366 Keyword: <quote>block</quote>, or any user defined value.
4375 Faking the browser's language settings can be useful to make a
4376 foreign User-Agent set with
4377 <literal><link linkend="hide-user-agent">hide-user-agent</link></literal>
4381 However some sites with content in different languages check the
4382 <quote>Accept-Language:</quote> to decide which one to take by default.
4383 Sometimes it isn't possible to later switch to another language without
4384 changing the <quote>Accept-Language:</quote> header first.
4387 Therefore it's a good idea to either only change the
4388 <quote>Accept-Language:</quote> header to languages you understand,
4389 or to languages that aren't wide spread.
4392 Before setting the <quote>Accept-Language:</quote> header
4393 to a rare language, you should consider that it helps to
4394 make your requests unique and thus easier to trace.
4395 If you don't plan to change this header frequently,
4396 you should stick to a common language.
4402 <term>Example usage (section):</term>
4405 <screen># Pretend to use Canadian language settings.
4406 {+hide-accept-language{en-ca} \
4407 +hide-user-agent{Mozilla/5.0 (X11; U; OpenBSD i386; en-CA; rv:1.8.0.4) Gecko/20060628 Firefox/1.5.0.4} \
4417 <!-- ~~~~~ New section ~~~~~ -->
4418 <sect3 renderas="sect4" id="hide-content-disposition">
4419 <title>hide-content-disposition</title>
4425 <term>Typical use:</term>
4427 <para>Prevent download menus for content you prefer to view inside the browser.</para>
4432 <term>Effect:</term>
4435 Deletes or replaces the <quote>Content-Disposition:</quote> HTTP header set by some servers.
4442 <!-- Boolean, Parameterized, Multi-value -->
4444 <para>Parameterized.</para>
4449 <term>Parameter:</term>
4452 Keyword: <quote>block</quote>, or any user defined value.
4461 Some servers set the <quote>Content-Disposition:</quote> HTTP header for
4462 documents they assume you want to save locally before viewing them.
4463 The <quote>Content-Disposition:</quote> header contains the file name
4464 the browser is supposed to use by default.
4467 In most browsers that understand this header, it makes it impossible to
4468 <emphasis>just view</emphasis> the document, without downloading it first,
4469 even if it's just a simple text file or an image.
4472 Removing the <quote>Content-Disposition:</quote> header helps
4473 to prevent this annoyance, but some browsers additionally check the
4474 <quote>Content-Type:</quote> header, before they decide if they can
4475 display a document without saving it first. In these cases, you have
4476 to change this header as well, before the browser stops displaying
4480 It is also possible to change the server's file name suggestion
4481 to another one, but in most cases it isn't worth the time to set
4485 This action will probably be removed in the future,
4486 use server-header filters instead.
4492 <term>Example usage:</term>
4495 <screen># Disarm the download link in Sourceforge's patch tracker
4497 +content-type-overwrite{text/plain}\
4498 +hide-content-disposition{block} }
4499 .sourceforge.net/tracker/download\.php</screen>
4507 <!-- ~~~~~ New section ~~~~~ -->
4508 <sect3 renderas="sect4" id="hide-if-modified-since">
4509 <title>hide-if-modified-since</title>
4515 <term>Typical use:</term>
4517 <para>Prevent yet another way to track the user's steps between sessions.</para>
4522 <term>Effect:</term>
4525 Deletes the <quote>If-Modified-Since:</quote> HTTP client header or modifies its value.
4532 <!-- Boolean, Parameterized, Multi-value -->
4534 <para>Parameterized.</para>
4539 <term>Parameter:</term>
4542 Keyword: <quote>block</quote>, or a user defined value that specifies a range of hours.
4551 Removing this header is useful for filter testing, where you want to force a real
4552 reload instead of getting status code <quote>304</quote>, which would cause the
4553 browser to use a cached copy of the page.
4556 Instead of removing the header, <literal>hide-if-modified-since</literal> can
4557 also add or subtract a random amount of time to/from the header's value.
4558 You specify a range of minutes where the random factor should be chosen from and
4559 <application>Privoxy</application> does the rest. A negative value means
4560 subtracting, a positive value adding.
4563 Randomizing the value of the <quote>If-Modified-Since:</quote> makes
4564 it less likely that the server can use the time as a cookie replacement,
4565 but you will run into caching problems if the random range is too high.
4568 It is a good idea to only use a small negative value and let
4569 <literal><link linkend="overwrite-last-modified">overwrite-last-modified</link></literal>
4570 handle the greater changes.
4573 It is also recommended to use this action together with
4574 <literal><link linkend="crunch-if-none-match">crunch-if-none-match</link></literal>,
4575 otherwise it's more or less pointless.
4581 <term>Example usage (section):</term>
4584 <screen># Let the browser revalidate but make tracking based on the time less likely.
4585 {+hide-if-modified-since{-60} \
4586 +overwrite-last-modified{randomize} \
4587 +crunch-if-none-match}
4596 <!-- ~~~~~ New section ~~~~~ -->
4597 <sect3 renderas="sect4" id="hide-from-header">
4598 <title>hide-from-header</title>
4602 <term>Typical use:</term>
4604 <para>Keep your (old and ill) browser from telling web servers your email address</para>
4609 <term>Effect:</term>
4612 Deletes any existing <quote>From:</quote> HTTP header, or replaces it with the
4620 <!-- Boolean, Parameterized, Multi-value -->
4622 <para>Parameterized.</para>
4627 <term>Parameter:</term>
4630 Keyword: <quote>block</quote>, or any user defined value.
4639 The keyword <quote>block</quote> will completely remove the header
4640 (not to be confused with the <literal><link linkend="block">block</link></literal>
4644 Alternately, you can specify any value you prefer to be sent to the web
4645 server. If you do, it is a matter of fairness not to use any address that
4646 is actually used by a real person.
4649 This action is rarely needed, as modern web browsers don't send
4650 <quote>From:</quote> headers anymore.
4656 <term>Example usage:</term>
4659 <screen>+hide-from-header{block}</screen> or
4660 <screen>+hide-from-header{spam-me-senseless@sittingduck.example.com}</screen>
4668 <!-- ~~~~~ New section ~~~~~ -->
4669 <sect3 renderas="sect4" id="hide-referrer">
4670 <title>hide-referrer</title>
4671 <anchor id="hide-referer">
4674 <term>Typical use:</term>
4676 <para>Conceal which link you followed to get to a particular site</para>
4681 <term>Effect:</term>
4684 Deletes the <quote>Referer:</quote> (sic) HTTP header from the client request,
4685 or replaces it with a forged one.
4692 <!-- Boolean, Parameterized, Multi-value -->
4694 <para>Parameterized.</para>
4699 <term>Parameter:</term>
4703 <para><quote>conditional-block</quote> to delete the header completely if the host has changed.</para>
4706 <para><quote>conditional-forge</quote> to forge the header if the host has changed.</para>
4709 <para><quote>block</quote> to delete the header unconditionally.</para>
4712 <para><quote>forge</quote> to pretend to be coming from the homepage of the server we are talking to.</para>
4715 <para>Any other string to set a user defined referrer.</para>
4725 <literal>conditional-block</literal> is the only parameter,
4726 that isn't easily detected in the server's log file. If it blocks the
4727 referrer, the request will look like the visitor used a bookmark or
4728 typed in the address directly.
4731 Leaving the referrer unmodified for requests on the same host
4732 allows the server owner to see the visitor's <quote>click path</quote>,
4733 but in most cases she could also get that information by comparing
4734 other parts of the log file: for example the User-Agent if it isn't
4735 a very common one, or the user's IP address if it doesn't change between
4739 Always blocking the referrer, or using a custom one, can lead to
4740 failures on servers that check the referrer before they answer any
4741 requests, in an attempt to prevent their content from being
4742 embedded or linked to elsewhere.
4745 Both <literal>conditional-block</literal> and <literal>forge</literal>
4746 will work with referrer checks, as long as content and valid referring page
4747 are on the same host. Most of the time that's the case.
4750 <literal>hide-referer</literal> is an alternate spelling of
4751 <literal>hide-referrer</literal> and the two can be can be freely
4752 substituted with each other. (<quote>referrer</quote> is the
4753 correct English spelling, however the HTTP specification has a bug - it
4754 requires it to be spelled as <quote>referer</quote>.)
4760 <term>Example usage:</term>
4763 <screen>+hide-referrer{forge}</screen> or
4764 <screen>+hide-referrer{http://www.yahoo.com/}</screen>
4772 <!-- ~~~~~ New section ~~~~~ -->
4773 <sect3 renderas="sect4" id="hide-user-agent">
4774 <title>hide-user-agent</title>
4778 <term>Typical use:</term>
4780 <para>Try to conceal your type of browser and client operating system</para>
4785 <term>Effect:</term>
4788 Replaces the value of the <quote>User-Agent:</quote> HTTP header
4789 in client requests with the specified value.
4796 <!-- Boolean, Parameterized, Multi-value -->
4798 <para>Parameterized.</para>
4803 <term>Parameter:</term>
4806 Any user-defined string.
4816 This can lead to problems on web sites that depend on looking at this header in
4817 order to customize their content for different browsers (which, by the
4818 way, is <emphasis>NOT</emphasis> the right thing to do: good web sites
4819 work browser-independently).
4823 Using this action in multi-user setups or wherever different types of
4824 browsers will access the same <application>Privoxy</application> is
4825 <emphasis>not recommended</emphasis>. In single-user, single-browser
4826 setups, you might use it to delete your OS version information from
4827 the headers, because it is an invitation to exploit known bugs for your
4828 OS. It is also occasionally useful to forge this in order to access
4829 sites that won't let you in otherwise (though there may be a good
4830 reason in some cases).
4833 More information on known user-agent strings can be found at
4834 <ulink url="http://www.user-agents.org/">http://www.user-agents.org/</ulink>
4836 <ulink url="http://en.wikipedia.org/wiki/User_agent">http://en.wikipedia.org/wiki/User_agent</ulink>.
4842 <term>Example usage:</term>
4845 <screen>+hide-user-agent{Netscape 6.1 (X11; I; Linux 2.4.18 i686)}</screen>
4853 <!-- ~~~~~ New section ~~~~~ -->
4854 <sect3 renderas="sect4" id="limit-connect">
4855 <title>limit-connect</title>
4859 <term>Typical use:</term>
4861 <para>Prevent abuse of <application>Privoxy</application> as a TCP proxy relay or disable SSL for untrusted sites</para>
4866 <term>Effect:</term>
4869 Specifies to which ports HTTP CONNECT requests are allowable.
4876 <!-- Boolean, Parameterized, Multi-value -->
4878 <para>Parameterized.</para>
4883 <term>Parameter:</term>
4886 A comma-separated list of ports or port ranges (the latter using dashes, with the minimum
4887 defaulting to 0 and the maximum to 65K).
4896 By default, i.e. if no <literal>limit-connect</literal> action applies,
4897 <application>Privoxy</application> allows HTTP CONNECT requests to all
4898 ports. Use <literal>limit-connect</literal> if fine-grained control
4899 is desired for some or all destinations.
4902 The CONNECT methods exists in HTTP to allow access to secure websites
4903 (<quote>https://</quote> URLs) through proxies. It works very simply:
4904 the proxy connects to the server on the specified port, and then
4905 short-circuits its connections to the client and to the remote server.
4906 This means CONNECT-enabled proxies can be used as TCP relays very easily.
4909 <application>Privoxy</application> relays HTTPS traffic without seeing
4910 the decoded content. Websites can leverage this limitation to circumvent &my-app;'s
4911 filters. By specifying an invalid port range you can disable HTTPS entirely.
4917 <term>Example usages:</term>
4919 <!-- I had trouble getting the spacing to look right in my browser -->
4920 <!-- I probably have the wrong font setup, bollocks. -->
4921 <!-- Apparently the emphasis tag uses a proportional font no matter what -->
4923 <screen>+limit-connect{443} # Port 443 is OK.
4924 +limit-connect{80,443} # Ports 80 and 443 are OK.
4925 +limit-connect{-3, 7, 20-100, 500-} # Ports less than 3, 7, 20 to 100 and above 500 are OK.
4926 +limit-connect{-} # All ports are OK
4927 +limit-connect{,} # No HTTPS/SSL traffic is allowed</screen>
4935 <!-- ~~~~~ New section ~~~~~ -->
4936 <sect3 renderas="sect4" id="limit-cookie-lifetime">
4937 <title>limit-cookie-lifetime</title>
4941 <term>Typical use:</term>
4943 <para>Limit the lifetime of HTTP cookies to a couple of minutes or hours.</para>
4948 <term>Effect:</term>
4951 Overwrites the expires field in Set-Cookie server headers if it's above the specified limit.
4958 <!-- Boolean, Parameterized, Multi-value -->
4960 <para>Parameterized.</para>
4965 <term>Parameter:</term>
4968 The lifetime limit in minutes, or 0.
4977 This action reduces the lifetime of HTTP cookies coming from the
4978 server to the specified number of minutes, starting from the time
4979 the cookie passes Privoxy.
4982 Cookies with a lifetime below the limit are not modified.
4983 The lifetime of session cookies is set to the specified limit.
4986 The effect of this action depends on the server.
4989 In case of servers which refresh their cookies with each response
4990 (or at least frequently), the lifetime limit set by this action
4992 Thus, a session associated with the cookie continues to work with
4993 this action enabled, as long as a new request is made before the
4994 last limit set is reached.
4997 However, some servers send their cookies once, with a lifetime of several
4998 years (the year 2037 is a popular choice), and do not refresh them
4999 until a certain event in the future, for example the user logging out.
5000 In this case this action may limit the absolute lifetime of the session,
5001 even if requests are made frequently.
5004 If the parameter is <quote>0</quote>, this action behaves like
5005 <literal><link linkend="session-cookies-only">session-cookies-only</link></literal>.
5011 <term>Example usages:</term>
5014 <screen>+limit-cookie-lifetime{60}
5022 <!-- ~~~~~ New section ~~~~~ -->
5023 <sect3 renderas="sect4" id="prevent-compression">
5024 <title>prevent-compression</title>
5028 <term>Typical use:</term>
5031 Ensure that servers send the content uncompressed, so it can be
5032 passed through <literal><link linkend="filter">filter</link></literal>s.
5038 <term>Effect:</term>
5041 Removes the Accept-Encoding header which can be used to ask for compressed transfer.
5048 <!-- Boolean, Parameterized, Multi-value -->
5050 <para>Boolean.</para>
5055 <term>Parameter:</term>
5067 More and more websites send their content compressed by default, which
5068 is generally a good idea and saves bandwidth. But the <literal><link
5069 linkend="filter">filter</link></literal> and
5070 <literal><link linkend="deanimate-gifs">deanimate-gifs</link></literal>
5071 actions need access to the uncompressed data.
5074 When compiled with zlib support (available since &my-app; 3.0.7), content that should be
5075 filtered is decompressed on-the-fly and you don't have to worry about this action.
5076 If you are using an older &my-app; version, or one that hasn't been compiled with zlib
5077 support, this action can be used to convince the server to send the content uncompressed.
5080 Most text-based instances compress very well, the size is seldom decreased by less than 50%,
5081 for markup-heavy instances like news feeds saving more than 90% of the original size isn't
5085 Not using compression will therefore slow down the transfer, and you should only
5086 enable this action if you really need it. As of &my-app; 3.0.7 it's disabled in all
5087 predefined action settings.
5090 Note that some (rare) ill-configured sites don't handle requests for uncompressed
5091 documents correctly. Broken PHP applications tend to send an empty document body,
5092 some IIS versions only send the beginning of the content. If you enable
5093 <literal>prevent-compression</literal> per default, you might want to add
5094 exceptions for those sites. See the example for how to do that.
5100 <term>Example usage (sections):</term>
5104 # Selectively turn off compression, and enable a filter
5106 { +filter{tiny-textforms} +prevent-compression }
5107 # Match only these sites
5112 # Or instead, we could set a universal default:
5114 { +prevent-compression }
5117 # Then maybe make exceptions for broken sites:
5119 { -prevent-compression }
5120 .compusa.com/</screen>
5129 <!-- ~~~~~ New section ~~~~~ -->
5130 <sect3 renderas="sect4" id="overwrite-last-modified">
5131 <title>overwrite-last-modified</title>
5137 <term>Typical use:</term>
5139 <para>Prevent yet another way to track the user's steps between sessions.</para>
5144 <term>Effect:</term>
5147 Deletes the <quote>Last-Modified:</quote> HTTP server header or modifies its value.
5154 <!-- Boolean, Parameterized, Multi-value -->
5156 <para>Parameterized.</para>
5161 <term>Parameter:</term>
5164 One of the keywords: <quote>block</quote>, <quote>reset-to-request-time</quote>
5165 and <quote>randomize</quote>
5174 Removing the <quote>Last-Modified:</quote> header is useful for filter
5175 testing, where you want to force a real reload instead of getting status
5176 code <quote>304</quote>, which would cause the browser to reuse the old
5177 version of the page.
5180 The <quote>randomize</quote> option overwrites the value of the
5181 <quote>Last-Modified:</quote> header with a randomly chosen time
5182 between the original value and the current time. In theory the server
5183 could send each document with a different <quote>Last-Modified:</quote>
5184 header to track visits without using cookies. <quote>Randomize</quote>
5185 makes it impossible and the browser can still revalidate cached documents.
5188 <quote>reset-to-request-time</quote> overwrites the value of the
5189 <quote>Last-Modified:</quote> header with the current time. You could use
5190 this option together with
5191 <literal><link linkend="hide-if-modified-since">hide-if-modified-since</link></literal>
5192 to further customize your random range.
5195 The preferred parameter here is <quote>randomize</quote>. It is safe
5196 to use, as long as the time settings are more or less correct.
5197 If the server sets the <quote>Last-Modified:</quote> header to the time
5198 of the request, the random range becomes zero and the value stays the same.
5199 Therefore you should later randomize it a second time with
5200 <literal><link linkend="hide-if-modified-since">hided-if-modified-since</link></literal>,
5204 It is also recommended to use this action together with
5205 <literal><link linkend="crunch-if-none-match">crunch-if-none-match</link></literal>.
5211 <term>Example usage:</term>
5214 <screen># Let the browser revalidate without being tracked across sessions
5215 { +hide-if-modified-since{-60} \
5216 +overwrite-last-modified{randomize} \
5217 +crunch-if-none-match}
5226 <!-- ~~~~~ New section ~~~~~ -->
5227 <sect3 renderas="sect4" id="redirect">
5228 <title>redirect</title>
5234 <term>Typical use:</term>
5237 Redirect requests to other sites.
5243 <term>Effect:</term>
5246 Convinces the browser that the requested document has been moved
5247 to another location and the browser should get it from there.
5254 <!-- Boolean, Parameterized, Multi-value -->
5256 <para>Parameterized</para>
5261 <term>Parameter:</term>
5264 An absolute URL or a single pcrs command.
5273 Requests to which this action applies are answered with a
5274 HTTP redirect to URLs of your choosing. The new URL is
5275 either provided as parameter, or derived by applying a
5276 single pcrs command to the original URL.
5279 The syntax for pcrs commands is documented in the
5280 <link linkend="filter-file">filter file</link> section.
5283 This action will be ignored if you use it together with
5284 <literal><link linkend="block">block</link></literal>.
5285 It can be combined with
5286 <literal><link linkend="fast-redirects">fast-redirects{check-decoded-url}</link></literal>
5287 to redirect to a decoded version of a rewritten URL.
5290 Use this action carefully, make sure not to create redirection loops
5291 and be aware that using your own redirects might make it
5292 possible to fingerprint your requests.
5295 In case of problems with your redirects, or simply to watch
5296 them working, enable <link linkend="DEBUG">debug 128</link>.
5302 <term>Example usages:</term>
5305 <screen># Replace example.com's style sheet with another one
5306 { +redirect{http://localhost/css-replacements/example.com.css} }
5307 example.com/stylesheet\.css
5309 # Create a short, easy to remember nickname for a favorite site
5310 # (relies on the browser to accept and forward invalid URLs to &my-app;)
5311 { +redirect{http://www.privoxy.org/user-manual/actions-file.html} }
5314 # Always use the expanded view for Undeadly.org articles
5315 # (Note the $ at the end of the URL pattern to make sure
5316 # the request for the rewritten URL isn't redirected as well)
5317 {+redirect{s@$@&mode=expanded@}}
5318 undeadly.org/cgi\?action=article&sid=\d*$
5320 # Redirect Google search requests to MSN
5321 {+redirect{s@^http://[^/]*/search\?q=([^&]*).*@http://search.msn.com/results.aspx?q=$1@}}
5324 # Redirect MSN search requests to Yahoo
5325 {+redirect{s@^http://[^/]*/results\.aspx\?q=([^&]*).*@http://search.yahoo.com/search?p=$1@}}
5326 search.msn.com//results\.aspx\?q=
5328 # Redirect remote requests for this manual
5329 # to the local version delivered by Privoxy
5330 {+redirect{s@^http://www@http://config@}}
5331 www.privoxy.org/user-manual/</screen>
5340 <!-- ~~~~~ New section ~~~~~ -->
5341 <sect3 renderas="sect4" id="server-header-filter">
5342 <title>server-header-filter</title>
5346 <term>Typical use:</term>
5349 Rewrite or remove single server headers.
5355 <term>Effect:</term>
5358 All server headers to which this action applies are filtered on-the-fly
5359 through the specified regular expression based substitutions.
5366 <!-- boolean, parameterized, Multi-value -->
5368 <para>Parameterized.</para>
5373 <term>Parameter:</term>
5376 The name of a server-header filter, as defined in one of the
5377 <link linkend="filter-file">filter files</link>.
5386 Server-header filters are applied to each header on its own, not to
5387 all at once. This makes it easier to diagnose problems, but on the downside
5388 you can't write filters that only change header x if header y's value is z.
5389 You can do that by using tags though.
5392 Server-header filters are executed after the other header actions have finished
5393 and use their output as input.
5396 Please refer to the <link linkend="filter-file">filter file chapter</link>
5397 to learn which server-header filters are available by default, and how to
5404 <term>Example usage (section):</term>
5408 {+server-header-filter{html-to-xml}}
5409 example.org/xml-instance-that-is-delivered-as-html
5411 {+server-header-filter{xml-to-html}}
5412 example.org/instance-that-is-delivered-as-xml-but-is-not
5422 <!-- ~~~~~ New section ~~~~~ -->
5423 <sect3 renderas="sect4" id="server-header-tagger">
5424 <title>server-header-tagger</title>
5428 <term>Typical use:</term>
5431 Enable or disable filters based on the Content-Type header.
5437 <term>Effect:</term>
5440 Server headers to which this action applies are filtered on-the-fly through
5441 the specified regular expression based substitutions, the result is used as
5449 <!-- boolean, parameterized, Multi-value -->
5451 <para>Parameterized.</para>
5456 <term>Parameter:</term>
5459 The name of a server-header tagger, as defined in one of the
5460 <link linkend="filter-file">filter files</link>.
5469 Server-header taggers are applied to each header on its own,
5470 and as the header isn't modified, each tagger <quote>sees</quote>
5474 Server-header taggers are executed before all other header actions
5475 that modify server headers. Their tags can be used to control
5476 all of the other server-header actions, the content filters
5477 and the crunch actions (<link linkend="redirect">redirect</link>
5478 and <link linkend="block">block</link>).
5481 Obviously crunching based on tags created by server-header taggers
5482 doesn't prevent the request from showing up in the server's log file.
5489 <term>Example usage (section):</term>
5493 # Tag every request with the content type declared by the server
5494 {+server-header-tagger{content-type}}
5505 <!-- ~~~~~ New section ~~~~~ -->
5506 <sect3 renderas="sect4" id="session-cookies-only">
5507 <title>session-cookies-only</title>
5511 <term>Typical use:</term>
5514 Allow only temporary <quote>session</quote> cookies (for the current
5515 browser session <emphasis>only</emphasis>).
5521 <term>Effect:</term>
5524 Deletes the <quote>expires</quote> field from <quote>Set-Cookie:</quote>
5525 server headers. Most browsers will not store such cookies permanently and
5526 forget them in between sessions.
5533 <!-- Boolean, Parameterized, Multi-value -->
5535 <para>Boolean.</para>
5540 <term>Parameter:</term>
5552 This is less strict than <literal><link linkend="crunch-incoming-cookies">crunch-incoming-cookies</link></literal> /
5553 <literal><link linkend="crunch-outgoing-cookies">crunch-outgoing-cookies</link></literal> and allows you to browse
5554 websites that insist or rely on setting cookies, without compromising your privacy too badly.
5557 Most browsers will not permanently store cookies that have been processed by
5558 <literal>session-cookies-only</literal> and will forget about them between sessions.
5559 This makes profiling cookies useless, but won't break sites which require cookies so
5560 that you can log in for transactions. This is generally turned on for all
5561 sites, and is the recommended setting.
5564 It makes <emphasis>no sense at all</emphasis> to use <literal>session-cookies-only</literal>
5565 together with <literal><link linkend="crunch-incoming-cookies">crunch-incoming-cookies</link></literal> or
5566 <literal><link linkend="crunch-outgoing-cookies">crunch-outgoing-cookies</link></literal>. If you do, cookies
5567 will be plainly killed.
5570 Note that it is up to the browser how it handles such cookies without an <quote>expires</quote>
5571 field. If you use an exotic browser, you might want to try it out to be sure.
5574 This setting also has no effect on cookies that may have been stored
5575 previously by the browser before starting <application>Privoxy</application>.
5576 These would have to be removed manually.
5579 <application>Privoxy</application> also uses
5580 the <link linkend="filter-content-cookies">content-cookies filter</link>
5581 to block some types of cookies. Content cookies are not effected by
5582 <literal>session-cookies-only</literal>.
5588 <term>Example usage:</term>
5591 <screen>+session-cookies-only</screen>
5599 <!-- ~~~~~ New section ~~~~~ -->
5600 <sect3 renderas="sect4" id="set-image-blocker">
5601 <title>set-image-blocker</title>
5605 <term>Typical use:</term>
5607 <para>Choose the replacement for blocked images</para>
5612 <term>Effect:</term>
5615 This action alone doesn't do anything noticeable. If <emphasis>both</emphasis>
5616 <literal><link linkend="block">block</link></literal> <emphasis>and</emphasis> <literal><link
5617 linkend="handle-as-image">handle-as-image</link></literal> <emphasis>also</emphasis>
5618 apply, i.e. if the request is to be blocked as an image,
5619 <emphasis>then</emphasis> the parameter of this action decides what will be
5620 sent as a replacement.
5627 <!-- Boolean, Parameterized, Multi-value -->
5629 <para>Parameterized.</para>
5634 <term>Parameter:</term>
5639 <quote>pattern</quote> to send a built-in checkerboard pattern image. The image is visually
5640 decent, scales very well, and makes it obvious where banners were busted.
5645 <quote>blank</quote> to send a built-in transparent image. This makes banners disappear
5646 completely, but makes it hard to detect where <application>Privoxy</application> has blocked
5647 images on a given page and complicates troubleshooting if <application>Privoxy</application>
5648 has blocked innocent images, like navigation icons.
5653 <quote><replaceable class="parameter">target-url</replaceable></quote> to
5654 send a redirect to <replaceable class="parameter">target-url</replaceable>. You can redirect
5655 to any image anywhere, even in your local filesystem via <quote>file:///</quote> URL.
5656 (But note that not all browsers support redirecting to a local file system).
5659 A good application of redirects is to use special <application>Privoxy</application>-built-in
5660 URLs, which send the built-in images, as <replaceable class="parameter">target-url</replaceable>.
5661 This has the same visual effect as specifying <quote>blank</quote> or <quote>pattern</quote> in
5662 the first place, but enables your browser to cache the replacement image, instead of requesting
5663 it over and over again.
5674 The URLs for the built-in images are <quote>http://config.privoxy.org/send-banner?type=<replaceable
5675 class="parameter">type</replaceable></quote>, where <replaceable class="parameter">type</replaceable> is
5676 either <quote>blank</quote> or <quote>pattern</quote>.
5679 There is a third (advanced) type, called <quote>auto</quote>. It is <emphasis>NOT</emphasis> to be
5680 used in <literal>set-image-blocker</literal>, but meant for use from <link linkend="filter-file">filters</link>.
5681 Auto will select the type of image that would have applied to the referring page, had it been an image.
5687 <term>Example usage:</term>
5693 <screen>+set-image-blocker{pattern}</screen>
5696 Redirect to the BSD daemon:
5699 <screen>+set-image-blocker{http://www.freebsd.org/gifs/dae_up3.gif}</screen>
5702 Redirect to the built-in pattern for better caching:
5705 <screen>+set-image-blocker{http://config.privoxy.org/send-banner?type=pattern}</screen>
5713 <!-- ~~~~~ New section ~~~~~ -->
5715 <title>Summary</title>
5717 Note that many of these actions have the potential to cause a page to
5718 misbehave, possibly even not to display at all. There are many ways
5719 a site designer may choose to design his site, and what HTTP header
5720 content, and other criteria, he may depend on. There is no way to have hard
5721 and fast rules for all sites. See the <link
5722 linkend="ACTIONSANAT">Appendix</link> for a brief example on troubleshooting
5728 <!-- ~~~~~ New section ~~~~~ -->
5729 <sect2 id="aliases">
5730 <title>Aliases</title>
5732 Custom <quote>actions</quote>, known to <application>Privoxy</application>
5733 as <quote>aliases</quote>, can be defined by combining other actions.
5734 These can in turn be invoked just like the built-in actions.
5735 Currently, an alias name can contain any character except space, tab,
5737 <quote>{</quote> and <quote>}</quote>, but we <emphasis>strongly
5738 recommend</emphasis> that you only use <quote>a</quote> to <quote>z</quote>,
5739 <quote>0</quote> to <quote>9</quote>, <quote>+</quote>, and <quote>-</quote>.
5740 Alias names are not case sensitive, and are not required to start with a
5741 <quote>+</quote> or <quote>-</quote> sign, since they are merely textually
5745 Aliases can be used throughout the actions file, but they <emphasis>must be
5746 defined in a special section at the top of the file!</emphasis>
5747 And there can only be one such section per actions file. Each actions file may
5748 have its own alias section, and the aliases defined in it are only visible
5752 There are two main reasons to use aliases: One is to save typing for frequently
5753 used combinations of actions, the other one is a gain in flexibility: If you
5754 decide once how you want to handle shops by defining an alias called
5755 <quote>shop</quote>, you can later change your policy on shops in
5756 <emphasis>one</emphasis> place, and your changes will take effect everywhere
5757 in the actions file where the <quote>shop</quote> alias is used. Calling aliases
5758 by their purpose also makes your actions files more readable.
5761 Currently, there is one big drawback to using aliases, though:
5762 <application>Privoxy</application>'s built-in web-based action file
5763 editor honors aliases when reading the actions files, but it expands
5764 them before writing. So the effects of your aliases are of course preserved,
5765 but the aliases themselves are lost when you edit sections that use aliases
5770 Now let's define some aliases...
5775 # Useful custom aliases we can use later.
5777 # Note the (required!) section header line and that this section
5778 # must be at the top of the actions file!
5782 # These aliases just save typing later:
5783 # (Note that some already use other aliases!)
5785 +crunch-all-cookies = +<link linkend="CRUNCH-INCOMING-COOKIES">crunch-incoming-cookies</link> +<link linkend="CRUNCH-OUTGOING-COOKIES">crunch-outgoing-cookies</link>
5786 -crunch-all-cookies = -<link linkend="CRUNCH-INCOMING-COOKIES">crunch-incoming-cookies</link> -<link linkend="CRUNCH-OUTGOING-COOKIES">crunch-outgoing-cookies</link>
5787 +block-as-image = +block{Blocked image.} +handle-as-image
5788 allow-all-cookies = -crunch-all-cookies -<link linkend="SESSION-COOKIES-ONLY">session-cookies-only</link> -<link linkend="FILTER-CONTENT-COOKIES">filter{content-cookies}</link>
5790 # These aliases define combinations of actions
5791 # that are useful for certain types of sites:
5793 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>
5795 shop = -crunch-all-cookies -<link linkend="FILTER-ALL-POPUPS">filter{all-popups}</link>
5797 # Short names for other aliases, for really lazy people ;-)
5799 c0 = +crunch-all-cookies
5800 c1 = -crunch-all-cookies</screen>
5804 ...and put them to use. These sections would appear in the lower part of an
5805 actions file and define exceptions to the default actions (as specified further
5806 up for the <quote>/</quote> pattern):
5811 # These sites are either very complex or very keen on
5812 # user data and require minimal interference to work:
5815 .office.microsoft.com
5816 .windowsupdate.microsoft.com
5817 # Gmail is really mail.google.com, not gmail.com
5821 # Allow cookies (for setting and retrieving your customer data)
5825 .worldpay.com # for quietpc.com
5828 # These shops require pop-ups:
5830 {-filter{all-popups} -filter{unsolicited-popups}}
5832 .overclockers.co.uk</screen>
5836 Aliases like <quote>shop</quote> and <quote>fragile</quote> are typically used for
5837 <quote>problem</quote> sites that require more than one action to be disabled
5838 in order to function properly.
5844 <!-- ~~~~~ New section ~~~~~ -->
5845 <sect2 id="act-examples">
5846 <title>Actions Files Tutorial</title>
5848 The above chapters have shown <link linkend="actions-file">which actions files
5849 there are and how they are organized</link>, how actions are <link
5850 linkend="actions">specified</link> and <link linkend="actions-apply">applied
5851 to URLs</link>, how <link linkend="af-patterns">patterns</link> work, and how to
5852 define and use <link linkend="aliases">aliases</link>. Now, let's look at an
5853 example <filename>match-all.action</filename>, <filename>default.action</filename>
5854 and <filename>user.action</filename> file and see how all these pieces come together:
5858 <title>match-all.action</title>
5860 Remember <emphasis>all actions are disabled when matching starts</emphasis>,
5861 so we have to explicitly enable the ones we want.
5865 While the <filename>match-all.action</filename> file only contains a
5866 single section, it is probably the most important one. It has only one
5867 pattern, <quote><literal>/</literal></quote>, but this pattern
5868 <link linkend="af-patterns">matches all URLs</link>. Therefore, the set of
5869 actions used in this <quote>default</quote> section <emphasis>will
5870 be applied to all requests as a start</emphasis>. It can be partly or
5871 wholly overridden by other actions files like <filename>default.action</filename>
5872 and <filename>user.action</filename>, but it will still be largely responsible
5873 for your overall browsing experience.
5877 Again, at the start of matching, all actions are disabled, so there is
5878 no need to disable any actions here. (Remember: a <quote>+</quote>
5879 preceding the action name enables the action, a <quote>-</quote> disables!).
5880 Also note how this long line has been made more readable by splitting it into
5881 multiple lines with line continuation.
5887 +<link linkend="CHANGE-X-FORWARDED-FOR">change-x-forwarded-for{block}</link> \
5888 +<link linkend="HIDE-FROM-HEADER">hide-from-header{block}</link> \
5889 +<link linkend="SET-IMAGE-BLOCKER">set-image-blocker{pattern}</link> \
5896 The default behavior is now set.
5901 <title>default.action</title>
5904 If you aren't a developer, there's no need for you to edit the
5905 <filename>default.action</filename> file. It is maintained by
5906 the &my-app; developers and if you disagree with some of the
5907 sections, you should overrule them in your <filename>user.action</filename>.
5911 Understanding the <filename>default.action</filename> file can
5912 help you with your <filename>user.action</filename>, though.
5916 The first section in this file is a special section for internal use
5917 that prevents older &my-app; versions from reading the file:
5922 ##########################################################################
5923 # Settings -- Don't change! For internal Privoxy use ONLY.
5924 ##########################################################################
5926 for-privoxy-version=3.0.11</screen>
5930 After that comes the (optional) alias section. We'll use the example
5931 section from the above <link linkend="aliases">chapter on aliases</link>,
5932 that also explains why and how aliases are used:
5937 ##########################################################################
5939 ##########################################################################
5942 # These aliases just save typing later:
5943 # (Note that some already use other aliases!)
5945 +crunch-all-cookies = +<link linkend="CRUNCH-INCOMING-COOKIES">crunch-incoming-cookies</link> +<link linkend="CRUNCH-OUTGOING-COOKIES">crunch-outgoing-cookies</link>
5946 -crunch-all-cookies = -<link linkend="CRUNCH-INCOMING-COOKIES">crunch-incoming-cookies</link> -<link linkend="CRUNCH-OUTGOING-COOKIES">crunch-outgoing-cookies</link>
5947 +block-as-image = +block{Blocked image.} +handle-as-image
5948 mercy-for-cookies = -crunch-all-cookies -<link linkend="SESSION-COOKIES-ONLY">session-cookies-only</link> -<link linkend="FILTER-CONTENT-COOKIES">filter{content-cookies}</link>
5950 # These aliases define combinations of actions
5951 # that are useful for certain types of sites:
5953 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>
5954 shop = -crunch-all-cookies -<link linkend="FILTER-ALL-POPUPS">filter{all-popups}</link></screen>
5958 The first of our specialized sections is concerned with <quote>fragile</quote>
5959 sites, i.e. sites that require minimum interference, because they are either
5960 very complex or very keen on tracking you (and have mechanisms in place that
5961 make them unusable for people who avoid being tracked). We will simply use
5962 our pre-defined <literal>fragile</literal> alias instead of stating the list
5963 of actions explicitly:
5968 ##########################################################################
5969 # Exceptions for sites that'll break under the default action set:
5970 ##########################################################################
5972 # "Fragile" Use a minimum set of actions for these sites (see alias above):
5975 .office.microsoft.com # surprise, surprise!
5976 .windowsupdate.microsoft.com
5977 mail.google.com</screen>
5981 Shopping sites are not as fragile, but they typically
5982 require cookies to log in, and pop-up windows for shopping
5983 carts or item details. Again, we'll use a pre-defined alias:
5992 .worldpay.com # for quietpc.com
5994 .scan.co.uk</screen>
5998 The <literal><link linkend="FAST-REDIRECTS">fast-redirects</link></literal>
5999 action, which may have been enabled in <filename>match-all.action</filename>,
6000 breaks some sites. So disable it for popular sites where we know it misbehaves:
6005 { -<link linkend="FAST-REDIRECTS">fast-redirects</link> }
6009 .altavista.com/.*(like|url|link):http
6010 .altavista.com/trans.*urltext=http
6011 .nytimes.com</screen>
6015 It is important that <application>Privoxy</application> knows which
6016 URLs belong to images, so that <emphasis>if</emphasis> they are to
6017 be blocked, a substitute image can be sent, rather than an HTML page.
6018 Contacting the remote site to find out is not an option, since it
6019 would destroy the loading time advantage of banner blocking, and it
6020 would feed the advertisers information about you. We can mark any
6021 URL as an image with the <literal><link
6022 linkend="handle-as-image">handle-as-image</link></literal> action,
6023 and marking all URLs that end in a known image file extension is a
6029 ##########################################################################
6031 ##########################################################################
6033 # Define which file types will be treated as images, in case they get
6034 # blocked further down this file:
6036 { +<link linkend="HANDLE-AS-IMAGE">handle-as-image</link> }
6037 /.*\.(gif|jpe?g|png|bmp|ico)$</screen>
6041 And then there are known banner sources. They often use scripts to
6042 generate the banners, so it won't be visible from the URL that the
6043 request is for an image. Hence we block them <emphasis>and</emphasis>
6044 mark them as images in one go, with the help of our
6045 <literal>+block-as-image</literal> alias defined above. (We could of
6046 course just as well use <literal>+<link linkend="block">block</link>
6047 +<link linkend="handle-as-image">handle-as-image</link></literal> here.)
6048 Remember that the type of the replacement image is chosen by the
6049 <literal><link linkend="set-image-blocker">set-image-blocker</link></literal>
6050 action. Since all URLs have matched the default section with its
6051 <literal>+<link linkend="set-image-blocker">set-image-blocker</link>{pattern}</literal>
6052 action before, it still applies and needn't be repeated:
6057 # Known ad generators:
6062 .ad.*.doubleclick.net
6063 .a.yimg.com/(?:(?!/i/).)*$
6064 .a[0-9].yimg.com/(?:(?!/i/).)*$
6070 One of the most important jobs of <application>Privoxy</application>
6071 is to block banners. Many of these can be <quote>blocked</quote>
6072 by the <literal><link linkend="filter">filter</link>{banners-by-size}</literal>
6073 action, which we enabled above, and which deletes the references to banner
6074 images from the pages while they are loaded, so the browser doesn't request
6075 them anymore, and hence they don't need to be blocked here. But this naturally
6076 doesn't catch all banners, and some people choose not to use filters, so we
6077 need a comprehensive list of patterns for banner URLs here, and apply the
6078 <literal><link linkend="block">block</link></literal> action to them.
6081 First comes many generic patterns, which do most of the work, by
6082 matching typical domain and path name components of banners. Then comes
6083 a list of individual patterns for specific sites, which is omitted here
6084 to keep the example short:
6089 ##########################################################################
6090 # Block these fine banners:
6091 ##########################################################################
6092 { <link linkend="BLOCK">+block{Banner ads.}</link> }
6100 /.*count(er)?\.(pl|cgi|exe|dll|asp|php[34]?)
6101 /(?:.*/)?(publicite|werbung|rekla(ma|me|am)|annonse|maino(kset|nta|s)?)/
6103 # Site-specific patterns (abbreviated):
6105 .hitbox.com</screen>
6109 It's quite remarkable how many advertisers actually call their banner
6110 servers ads.<replaceable>company</replaceable>.com, or call the directory
6111 in which the banners are stored simply <quote>banners</quote>. So the above
6112 generic patterns are surprisingly effective.
6115 But being very generic, they necessarily also catch URLs that we don't want
6116 to block. The pattern <literal>.*ads.</literal> e.g. catches
6117 <quote>nasty-<emphasis>ads</emphasis>.nasty-corp.com</quote> as intended,
6118 but also <quote>downlo<emphasis>ads</emphasis>.sourcefroge.net</quote> or
6119 <quote><emphasis>ads</emphasis>l.some-provider.net.</quote> So here come some
6120 well-known exceptions to the <literal>+<link linkend="BLOCK">block</link></literal>
6124 Note that these are exceptions to exceptions from the default! Consider the URL
6125 <quote>downloads.sourcefroge.net</quote>: Initially, all actions are deactivated,
6126 so it wouldn't get blocked. Then comes the defaults section, which matches the
6127 URL, but just deactivates the <literal><link linkend="BLOCK">block</link></literal>
6128 action once again. Then it matches <literal>.*ads.</literal>, an exception to the
6129 general non-blocking policy, and suddenly
6130 <literal><link linkend="BLOCK">+block</link></literal> applies. And now, it'll match
6131 <literal>.*loads.</literal>, where <literal><link linkend="BLOCK">-block</link></literal>
6132 applies, so (unless it matches <emphasis>again</emphasis> further down) it ends up
6133 with no <literal><link linkend="BLOCK">block</link></literal> action applying.
6138 ##########################################################################
6139 # Save some innocent victims of the above generic block patterns:
6140 ##########################################################################
6144 { -<link linkend="BLOCK">block</link> }
6145 adv[io]*. # (for advogato.org and advice.*)
6146 adsl. # (has nothing to do with ads)
6147 adobe. # (has nothing to do with ads either)
6148 ad[ud]*. # (adult.* and add.*)
6149 .edu # (universities don't host banners (yet!))
6150 .*loads. # (downloads, uploads etc)
6158 www.globalintersec.com/adv # (adv = advanced)
6159 www.ugu.com/sui/ugu/adv</screen>
6163 Filtering source code can have nasty side effects,
6164 so make an exception for our friends at sourceforge.net,
6165 and all paths with <quote>cvs</quote> in them. Note that
6166 <literal>-<link linkend="FILTER">filter</link></literal>
6167 disables <emphasis>all</emphasis> filters in one fell swoop!
6172 # Don't filter code!
6174 { -<link linkend="FILTER">filter</link> }
6179 .sourceforge.net</screen>
6183 The actual <filename>default.action</filename> is of course much more
6184 comprehensive, but we hope this example made clear how it works.
6189 <sect3><title>user.action</title>
6192 So far we are painting with a broad brush by setting general policies,
6193 which would be a reasonable starting point for many people. Now,
6194 you might want to be more specific and have customized rules that
6195 are more suitable to your personal habits and preferences. These would
6196 be for narrowly defined situations like your ISP or your bank, and should
6197 be placed in <filename>user.action</filename>, which is parsed after all other
6198 actions files and hence has the last word, over-riding any previously
6199 defined actions. <filename>user.action</filename> is also a
6200 <emphasis>safe</emphasis> place for your personal settings, since
6201 <filename>default.action</filename> is actively maintained by the
6202 <application>Privoxy</application> developers and you'll probably want
6203 to install updated versions from time to time.
6207 So let's look at a few examples of things that one might typically do in
6208 <filename>user.action</filename>:
6212 <!-- brief sample user.action here -->
6216 # My user.action file. <fred@example.com></screen>
6220 As <link linkend="aliases">aliases</link> are local to the actions
6221 file that they are defined in, you can't use the ones from
6222 <filename>default.action</filename>, unless you repeat them here:
6227 # Aliases are local to the file they are defined in.
6228 # (Re-)define aliases for this file:
6232 # These aliases just save typing later, and the alias names should
6233 # be self explanatory.
6235 +crunch-all-cookies = +crunch-incoming-cookies +crunch-outgoing-cookies
6236 -crunch-all-cookies = -crunch-incoming-cookies -crunch-outgoing-cookies
6237 allow-all-cookies = -crunch-all-cookies -session-cookies-only
6238 allow-popups = -filter{all-popups}
6239 +block-as-image = +block{Blocked as image.} +handle-as-image
6240 -block-as-image = -block
6242 # These aliases define combinations of actions that are useful for
6243 # certain types of sites:
6245 fragile = -block -crunch-all-cookies -filter -fast-redirects -hide-referrer
6246 shop = -crunch-all-cookies allow-popups
6248 # Allow ads for selected useful free sites:
6250 allow-ads = -block -filter{banners-by-size} -filter{banners-by-link}
6252 # Alias for specific file types that are text, but might have conflicting
6253 # MIME types. We want the browser to force these to be text documents.
6254 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>
6259 Say you have accounts on some sites that you visit regularly, and
6260 you don't want to have to log in manually each time. So you'd like
6261 to allow persistent cookies for these sites. The
6262 <literal>allow-all-cookies</literal> alias defined above does exactly
6263 that, i.e. it disables crunching of cookies in any direction, and the
6264 processing of cookies to make them only temporary.
6269 { allow-all-cookies }
6273 .redhat.com</screen>
6277 Your bank is allergic to some filter, but you don't know which, so you disable them all:
6282 { -<link linkend="FILTER">filter</link> }
6283 .your-home-banking-site.com</screen>
6287 Some file types you may not want to filter for various reasons:
6292 # Technical documentation is likely to contain strings that might
6293 # erroneously get altered by the JavaScript-oriented filters:
6298 # And this stupid host sends streaming video with a wrong MIME type,
6299 # so that Privoxy thinks it is getting HTML and starts filtering:
6301 stupid-server.example.com/</screen>
6305 Example of a simple <link linkend="BLOCK">block</link> action. Say you've
6306 seen an ad on your favourite page on example.com that you want to get rid of.
6307 You have right-clicked the image, selected <quote>copy image location</quote>
6308 and pasted the URL below while removing the leading http://, into a
6309 <literal>{ +block{} }</literal> section. Note that <literal>{ +handle-as-image
6310 }</literal> need not be specified, since all URLs ending in
6311 <literal>.gif</literal> will be tagged as images by the general rules as set
6312 in default.action anyway:
6317 { +<link linkend="BLOCK">block</link>{Nasty ads.} }
6318 www.example.com/nasty-ads/sponsor\.gif
6319 another.example.net/more/junk/here/</screen>
6323 The URLs of dynamically generated banners, especially from large banner
6324 farms, often don't use the well-known image file name extensions, which
6325 makes it impossible for <application>Privoxy</application> to guess
6326 the file type just by looking at the URL.
6327 You can use the <literal>+block-as-image</literal> alias defined above for
6329 Note that objects which match this rule but then turn out NOT to be an
6330 image are typically rendered as a <quote>broken image</quote> icon by the
6331 browser. Use cautiously.
6340 ar.atwola.com/</screen>
6344 Now you noticed that the default configuration breaks Forbes Magazine,
6345 but you were too lazy to find out which action is the culprit, and you
6346 were again too lazy to give <link linkend="contact">feedback</link>, so
6347 you just used the <literal>fragile</literal> alias on the site, and
6348 -- <emphasis>whoa!</emphasis> -- it worked. The <literal>fragile</literal>
6349 aliases disables those actions that are most likely to break a site. Also,
6350 good for testing purposes to see if it is <application>Privoxy</application>
6351 that is causing the problem or not. We later find other regular sites
6352 that misbehave, and add those to our personalized list of troublemakers:
6360 .mybank.com</screen>
6364 You like the <quote>fun</quote> text replacements in <filename>default.filter</filename>,
6365 but it is disabled in the distributed actions file.
6366 So you'd like to turn it on in your private,
6367 update-safe config, once and for all:
6372 { +<link linkend="filter-fun">filter{fun}</link> }
6373 / # For ALL sites!</screen>
6377 Note that the above is not really a good idea: There are exceptions
6378 to the filters in <filename>default.action</filename> for things that
6379 really shouldn't be filtered, like code on CVS->Web interfaces. Since
6380 <filename>user.action</filename> has the last word, these exceptions
6381 won't be valid for the <quote>fun</quote> filtering specified here.
6385 You might also worry about how your favourite free websites are
6386 funded, and find that they rely on displaying banner advertisements
6387 to survive. So you might want to specifically allow banners for those
6388 sites that you feel provide value to you:
6400 Note that <literal>allow-ads</literal> has been aliased to
6401 <literal>-<link linkend="block">block</link></literal>,
6402 <literal>-<link linkend="filter-banners-by-size">filter{banners-by-size}</link></literal>, and
6403 <literal>-<link linkend="filter-banners-by-link">filter{banners-by-link}</link></literal> above.
6407 Invoke another alias here to force an over-ride of the MIME type <literal>
6408 application/x-sh</literal> which typically would open a download type
6409 dialog. In my case, I want to look at the shell script, and then I can save
6410 it should I choose to.
6420 <filename>user.action</filename> is generally the best place to define
6421 exceptions and additions to the default policies of
6422 <filename>default.action</filename>. Some actions are safe to have their
6423 default policies set here though. So let's set a default policy to have a
6424 <quote>blank</quote> image as opposed to the checkerboard pattern for
6425 <emphasis>ALL</emphasis> sites. <quote>/</quote> of course matches all URL
6431 { +<link linkend="set-image-blocker">set-image-blocker{blank}</link> }
6432 / # ALL sites</screen>
6438 <!-- ~ End section ~ -->
6442 <!-- ~ End section ~ -->
6444 <!-- ~~~~~~~~ New section Header ~~~~~~~~~ -->
6446 <sect1 id="filter-file">
6447 <title>Filter Files</title>
6450 On-the-fly text substitutions need
6451 to be defined in a <quote>filter file</quote>. Once defined, they
6452 can then be invoked as an <quote>action</quote>.
6456 &my-app; supports three different filter actions:
6457 <literal><link linkend="filter">filter</link></literal> to
6458 rewrite the content that is send to the client,
6459 <literal><link linkend="client-header-filter">client-header-filter</link></literal>
6460 to rewrite headers that are send by the client, and
6461 <literal><link linkend="server-header-filter">server-header-filter</link></literal>
6462 to rewrite headers that are send by the server.
6466 &my-app; also supports two tagger actions:
6467 <literal><link linkend="client-header-tagger">client-header-tagger</link></literal>
6469 <literal><link linkend="server-header-tagger">server-header-tagger</link></literal>.
6470 Taggers and filters use the same syntax in the filter files, the difference
6471 is that taggers don't modify the text they are filtering, but use a rewritten
6472 version of the filtered text as tag. The tags can then be used to change the
6473 applying actions through sections with <link linkend="tag-pattern">tag-patterns</link>.
6478 Multiple filter files can be defined through the <literal> <link
6479 linkend="filterfile">filterfile</link></literal> config directive. The filters
6480 as supplied by the developers are located in
6481 <filename>default.filter</filename>. It is recommended that any locally
6482 defined or modified filters go in a separately defined file such as
6483 <filename>user.filter</filename>.
6487 Common tasks for content filters are to eliminate common annoyances in
6488 HTML and JavaScript, such as pop-up windows,
6489 exit consoles, crippled windows without navigation tools, the
6490 infamous <BLINK> tag etc, to suppress images with certain
6491 width and height attributes (standard banner sizes or web-bugs),
6492 or just to have fun.
6496 Enabled content filters are applied to any content whose
6497 <quote>Content Type</quote> header is recognised as a sign
6498 of text-based content, with the exception of <literal>text/plain</literal>.
6499 Use the <link linkend="FORCE-TEXT-MODE">force-text-mode</link> action
6500 to also filter other content.
6504 Substitutions are made at the source level, so if you want to <quote>roll
6505 your own</quote> filters, you should first be familiar with HTML syntax,
6506 and, of course, regular expressions.
6510 Just like the <link linkend="actions-file">actions files</link>, the
6511 filter file is organized in sections, which are called <emphasis>filters</emphasis>
6512 here. Each filter consists of a heading line, that starts with one of the
6513 <emphasis>keywords</emphasis> <literal>FILTER:</literal>,
6514 <literal>CLIENT-HEADER-FILTER:</literal> or <literal>SERVER-HEADER-FILTER:</literal>
6515 followed by the filter's <emphasis>name</emphasis>, and a short (one line)
6516 <emphasis>description</emphasis> of what it does. Below that line
6517 come the <emphasis>jobs</emphasis>, i.e. lines that define the actual
6518 text substitutions. By convention, the name of a filter
6519 should describe what the filter <emphasis>eliminates</emphasis>. The
6520 comment is used in the <ulink url="http://config.privoxy.org/">web-based
6521 user interface</ulink>.
6525 Once a filter called <replaceable>name</replaceable> has been defined
6526 in the filter file, it can be invoked by using an action of the form
6527 +<literal><link linkend="filter">filter</link>{<replaceable>name</replaceable>}</literal>
6528 in any <link linkend="actions-file">actions file</link>.
6532 Filter definitions start with a header line that contains the filter
6533 type, the filter name and the filter description.
6534 A content filter header line for a filter called <quote>foo</quote> could look
6539 <screen>FILTER: foo Replace all "foo" with "bar"</screen>
6543 Below that line, and up to the next header line, come the jobs that
6544 define what text replacements the filter executes. They are specified
6545 in a syntax that imitates <ulink url="http://www.perl.org/">Perl</ulink>'s
6546 <literal>s///</literal> operator. If you are familiar with Perl, you
6547 will find this to be quite intuitive, and may want to look at the
6548 PCRS documentation for the subtle differences to Perl behaviour.
6552 Most notably, the non-standard option letter <literal>U</literal> is supported,
6553 which turns the default to ungreedy matching (add <literal>?</literal> to
6554 quantifiers to turn them greedy again).
6558 The non-standard option letter <literal>D</literal> (dynamic) allows
6559 to use the variables $host, $origin (the IP address the request came from),
6560 $path and $url. They will be replaced with the value they refer to before
6561 the filter is executed.
6565 Note that '$' is a bad choice for a delimiter in a dynamic filter as you
6566 might end up with unintended variables if you use a variable name
6567 directly after the delimiter. Variables will be resolved without
6568 escaping anything, therefore you also have to be careful not to chose
6569 delimiters that appear in the replacement text. For example '<' should
6570 be save, while '?' will sooner or later cause conflicts with $url.
6574 The non-standard option letter <literal>T</literal> (trivial) prevents
6575 parsing for backreferences in the substitute. Use it if you want to include
6576 text like '$&' in your substitute without quoting.
6581 <ulink url="http://en.wikipedia.org/wiki/Regular_expressions"><quote>Regular
6582 Expressions</quote></ulink>, you might want to take a look at
6583 the <link linkend="regex">Appendix on regular expressions</link>, and
6584 see the <ulink url="http://perldoc.perl.org/perlre.html">Perl
6586 <ulink url="http://perldoc.perl.org/perlop.html">the
6587 <literal>s///</literal> operator's syntax</ulink> and <ulink
6588 url="http://perldoc.perl.org/perlre.html">Perl-style regular
6589 expressions</ulink> in general.
6590 The below examples might also help to get you started.
6594 <!-- ~~~~~~~~ New section Header ~~~~~~~~~ -->
6596 <sect2><title>Filter File Tutorial</title>
6598 Now, let's complete our <quote>foo</quote> content filter. We have already defined
6599 the heading, but the jobs are still missing. Since all it does is to replace
6600 <quote>foo</quote> with <quote>bar</quote>, there is only one (trivial) job
6605 <screen>s/foo/bar/</screen>
6609 But wait! Didn't the comment say that <emphasis>all</emphasis> occurrences
6610 of <quote>foo</quote> should be replaced? Our current job will only take
6611 care of the first <quote>foo</quote> on each page. For global substitution,
6612 we'll need to add the <literal>g</literal> option:
6616 <screen>s/foo/bar/g</screen>
6620 Our complete filter now looks like this:
6623 <screen>FILTER: foo Replace all "foo" with "bar"
6624 s/foo/bar/g</screen>
6628 Let's look at some real filters for more interesting examples. Here you see
6629 a filter that protects against some common annoyances that arise from JavaScript
6630 abuse. Let's look at its jobs one after the other:
6636 FILTER: js-annoyances Get rid of particularly annoying JavaScript abuse
6638 # Get rid of JavaScript referrer tracking. Test page: http://www.randomoddness.com/untitled.htm
6640 s|(<script.*)document\.referrer(.*</script>)|$1"Not Your Business!"$2|Usg</screen>
6644 Following the header line and a comment, you see the job. Note that it uses
6645 <literal>|</literal> as the delimiter instead of <literal>/</literal>, because
6646 the pattern contains a forward slash, which would otherwise have to be escaped
6647 by a backslash (<literal>\</literal>).
6651 Now, let's examine the pattern: it starts with the text <literal><script.*</literal>
6652 enclosed in parentheses. Since the dot matches any character, and <literal>*</literal>
6653 means: <quote>Match an arbitrary number of the element left of myself</quote>, this
6654 matches <quote><script</quote>, followed by <emphasis>any</emphasis> text, i.e.
6655 it matches the whole page, from the start of the first <script> tag.
6659 That's more than we want, but the pattern continues: <literal>document\.referrer</literal>
6660 matches only the exact string <quote>document.referrer</quote>. The dot needed to
6661 be <emphasis>escaped</emphasis>, i.e. preceded by a backslash, to take away its
6662 special meaning as a joker, and make it just a regular dot. So far, the meaning is:
6663 Match from the start of the first <script> tag in a the page, up to, and including,
6664 the text <quote>document.referrer</quote>, if <emphasis>both</emphasis> are present
6665 in the page (and appear in that order).
6669 But there's still more pattern to go. The next element, again enclosed in parentheses,
6670 is <literal>.*</script></literal>. You already know what <literal>.*</literal>
6671 means, so the whole pattern translates to: Match from the start of the first <script>
6672 tag in a page to the end of the last <script> tag, provided that the text
6673 <quote>document.referrer</quote> appears somewhere in between.
6677 This is still not the whole story, since we have ignored the options and the parentheses:
6678 The portions of the page matched by sub-patterns that are enclosed in parentheses, will be
6679 remembered and be available through the variables <literal>$1, $2, ...</literal> in
6680 the substitute. The <literal>U</literal> option switches to ungreedy matching, which means
6681 that the first <literal>.*</literal> in the pattern will only <quote>eat up</quote> all
6682 text in between <quote><script</quote> and the <emphasis>first</emphasis> occurrence
6683 of <quote>document.referrer</quote>, and that the second <literal>.*</literal> will
6684 only span the text up to the <emphasis>first</emphasis> <quote></script></quote>
6685 tag. Furthermore, the <literal>s</literal> option says that the match may span
6686 multiple lines in the page, and the <literal>g</literal> option again means that the
6687 substitution is global.
6691 So, to summarize, the pattern means: Match all scripts that contain the text
6692 <quote>document.referrer</quote>. Remember the parts of the script from
6693 (and including) the start tag up to (and excluding) the string
6694 <quote>document.referrer</quote> as <literal>$1</literal>, and the part following
6695 that string, up to and including the closing tag, as <literal>$2</literal>.
6699 Now the pattern is deciphered, but wasn't this about substituting things? So
6700 lets look at the substitute: <literal>$1"Not Your Business!"$2</literal> is
6701 easy to read: The text remembered as <literal>$1</literal>, followed by
6702 <literal>"Not Your Business!"</literal> (<emphasis>including</emphasis>
6703 the quotation marks!), followed by the text remembered as <literal>$2</literal>.
6704 This produces an exact copy of the original string, with the middle part
6705 (the <quote>document.referrer</quote>) replaced by <literal>"Not Your
6706 Business!"</literal>.
6710 The whole job now reads: Replace <quote>document.referrer</quote> by
6711 <literal>"Not Your Business!"</literal> wherever it appears inside a
6712 <script> tag. Note that this job won't break JavaScript syntax,
6713 since both the original and the replacement are syntactically valid
6714 string objects. The script just won't have access to the referrer
6715 information anymore.
6719 We'll show you two other jobs from the JavaScript taming department, but
6720 this time only point out the constructs of special interest:
6725 # The status bar is for displaying link targets, not pointless blahblah
6727 s/window\.status\s*=\s*(['"]).*?\1/dUmMy=1/ig</screen>
6731 <literal>\s</literal> stands for whitespace characters (space, tab, newline,
6732 carriage return, form feed), so that <literal>\s*</literal> means: <quote>zero
6733 or more whitespace</quote>. The <literal>?</literal> in <literal>.*?</literal>
6734 makes this matching of arbitrary text ungreedy. (Note that the <literal>U</literal>
6735 option is not set). The <literal>['"]</literal> construct means: <quote>a single
6736 <emphasis>or</emphasis> a double quote</quote>. Finally, <literal>\1</literal> is
6737 a back-reference to the first parenthesis just like <literal>$1</literal> above,
6738 with the difference that in the <emphasis>pattern</emphasis>, a backslash indicates
6739 a back-reference, whereas in the <emphasis>substitute</emphasis>, it's the dollar.
6743 So what does this job do? It replaces assignments of single- or double-quoted
6744 strings to the <quote>window.status</quote> object with a dummy assignment
6745 (using a variable name that is hopefully odd enough not to conflict with
6746 real variables in scripts). Thus, it catches many cases where e.g. pointless
6747 descriptions are displayed in the status bar instead of the link target when
6748 you move your mouse over links.
6753 # Kill OnUnload popups. Yummy. Test: http://www.zdnet.com/zdsubs/yahoo/tree/yfs.html
6755 s/(<body [^>]*)onunload(.*>)/$1never$2/iU</screen>
6760 <ulink url="http://www.w3.org/TR/2000/REC-DOM-Level-2-Events-20001113/events.html#Events-eventgroupings-htmlevents">OnUnload
6761 event binding</ulink> in the HTML DOM was a <emphasis>CRIME</emphasis>.
6762 When I close a browser window, I want it to close and die. Basta.
6763 This job replaces the <quote>onunload</quote> attribute in
6764 <quote><body></quote> tags with the dummy word <literal>never</literal>.
6765 Note that the <literal>i</literal> option makes the pattern matching
6766 case-insensitive. Also note that ungreedy matching alone doesn't always guarantee
6767 a minimal match: In the first parenthesis, we had to use <literal>[^>]*</literal>
6768 instead of <literal>.*</literal> to prevent the match from exceeding the
6769 <body> tag if it doesn't contain <quote>OnUnload</quote>, but the page's
6774 The last example is from the fun department:
6779 FILTER: fun Fun text replacements
6781 # Spice the daily news:
6783 s/microsoft(?!\.com)/MicroSuck/ig</screen>
6787 Note the <literal>(?!\.com)</literal> part (a so-called negative lookahead)
6788 in the job's pattern, which means: Don't match, if the string
6789 <quote>.com</quote> appears directly following <quote>microsoft</quote>
6790 in the page. This prevents links to microsoft.com from being trashed, while
6791 still replacing the word everywhere else.
6796 # Buzzword Bingo (example for extended regex syntax)
6798 s* industry[ -]leading \
6800 | customer[ -]focused \
6801 | market[ -]driven \
6802 | award[ -]winning # Comments are OK, too! \
6803 | high[ -]performance \
6804 | solutions[ -]based \
6808 *<font color="red"><b>BINGO!</b></font> \
6813 The <literal>x</literal> option in this job turns on extended syntax, and allows for
6814 e.g. the liberal use of (non-interpreted!) whitespace for nicer formatting.
6822 <!-- ~~~~~~~~ New section Header ~~~~~~~~~ -->
6824 <sect2 id="predefined-filters"><title>The Pre-defined Filters</title>
6828 Note each filter is also listed in the +filter action section above. Please
6829 keep these listings in sync.
6834 The distribution <filename>default.filter</filename> file contains a selection of
6835 pre-defined filters for your convenience:
6840 <term><emphasis>js-annoyances</emphasis></term>
6843 The purpose of this filter is to get rid of particularly annoying JavaScript abuse.
6848 replaces JavaScript references to the browser's referrer information
6849 with the string "Not Your Business!". This compliments the <literal><link
6850 linkend="hide-referrer">hide-referrer</link></literal> action on the content level.
6855 removes the bindings to the DOM's
6856 <ulink url="http://www.w3.org/TR/2000/REC-DOM-Level-2-Events-20001113/events.html#Events-eventgroupings-htmlevents">unload
6857 event</ulink> which we feel has no right to exist and is responsible for most <quote>exit consoles</quote>, i.e.
6858 nasty windows that pop up when you close another one.
6863 removes code that causes new windows to be opened with undesired properties, such as being
6864 full-screen, non-resizeable, without location, status or menu bar etc.
6870 Use with caution. This is an aggressive filter, and can break sites that
6871 rely heavily on JavaScript.
6877 <term><emphasis>js-events</emphasis></term>
6880 This is a very radical measure. It removes virtually all JavaScript event bindings, which
6881 means that scripts can not react to user actions such as mouse movements or clicks, window
6882 resizing etc, anymore. Use with caution!
6885 We <emphasis>strongly discourage</emphasis> using this filter as a default since it breaks
6886 many legitimate scripts. It is meant for use only on extra-nasty sites (should you really
6893 <term><emphasis>html-annoyances</emphasis></term>
6896 This filter will undo many common instances of HTML based abuse.
6899 The <literal>BLINK</literal> and <literal>MARQUEE</literal> tags
6900 are neutralized (yeah baby!), and browser windows will be created as
6901 resizeable (as of course they should be!), and will have location,
6902 scroll and menu bars -- even if specified otherwise.
6908 <term><emphasis>content-cookies</emphasis></term>
6911 Most cookies are set in the HTTP dialog, where they can be intercepted
6913 <literal><link linkend="crunch-incoming-cookies">crunch-incoming-cookies</link></literal>
6914 and <literal><link linkend="crunch-outgoing-cookies">crunch-outgoing-cookies</link></literal>
6915 actions. But web sites increasingly make use of HTML meta tags and JavaScript
6916 to sneak cookies to the browser on the content level.
6919 This filter disables most HTML and JavaScript code that reads or sets
6920 cookies. It cannot detect all clever uses of these types of code, so it
6921 should not be relied on as an absolute fix. Use it wherever you would also
6922 use the cookie crunch actions.
6928 <term><emphasis>refresh-tags</emphasis></term>
6931 Disable any refresh tags if the interval is greater than nine seconds (so
6932 that redirections done via refresh tags are not destroyed). This is useful
6933 for dial-on-demand setups, or for those who find this HTML feature
6940 <term><emphasis>unsolicited-popups</emphasis></term>
6943 This filter attempts to prevent only <quote>unsolicited</quote> pop-up
6944 windows from opening, yet still allow pop-up windows that the user
6945 has explicitly chosen to open. It was added in version 3.0.1,
6946 as an improvement over earlier such filters.
6949 Technical note: The filter works by redefining the window.open JavaScript
6950 function to a dummy function, <literal>PrivoxyWindowOpen()</literal>,
6951 during the loading and rendering phase of each HTML page access, and
6952 restoring the function afterward.
6955 This is recommended only for browsers that cannot perform this function
6956 reliably themselves. And be aware that some sites require such windows
6957 in order to function normally. Use with caution.
6963 <term><emphasis>all-popups</emphasis></term>
6966 Attempt to prevent <emphasis>all</emphasis> pop-up windows from opening.
6967 Note this should be used with even more discretion than the above, since
6968 it is more likely to break some sites that require pop-ups for normal
6969 usage. Use with caution.
6975 <term><emphasis>img-reorder</emphasis></term>
6978 This is a helper filter that has no value if used alone. It makes the
6979 <literal>banners-by-size</literal> and <literal>banners-by-link</literal>
6980 (see below) filters more effective and should be enabled together with them.
6986 <term><emphasis>banners-by-size</emphasis></term>
6989 This filter removes image tags purely based on what size they are. Fortunately
6990 for us, many ads and banner images tend to conform to certain standardized
6991 sizes, which makes this filter quite effective for ad stripping purposes.
6994 Occasionally this filter will cause false positives on images that are not ads,
6995 but just happen to be of one of the standard banner sizes.
6998 Recommended only for those who require extreme ad blocking. The default
6999 block rules should catch 95+% of all ads <emphasis>without</emphasis> this filter enabled.
7005 <term><emphasis>banners-by-link</emphasis></term>
7008 This is an experimental filter that attempts to kill any banners if
7009 their URLs seem to point to known or suspected click trackers. It is currently
7010 not of much value and is not recommended for use by default.
7016 <term><emphasis>webbugs</emphasis></term>
7019 Webbugs are small, invisible images (technically 1X1 GIF images), that
7020 are used to track users across websites, and collect information on them.
7021 As an HTML page is loaded by the browser, an embedded image tag causes the
7022 browser to contact a third-party site, disclosing the tracking information
7023 through the requested URL and/or cookies for that third-party domain, without
7024 the user ever becoming aware of the interaction with the third-party site.
7025 HTML-ized spam also uses a similar technique to verify email addresses.
7028 This filter removes the HTML code that loads such <quote>webbugs</quote>.
7034 <term><emphasis>tiny-textforms</emphasis></term>
7037 A rather special-purpose filter that can be used to enlarge textareas (those
7038 multi-line text boxes in web forms) and turn off hard word wrap in them.
7039 It was written for the sourceforge.net tracker system where such boxes are
7040 a nuisance, but it can be handy on other sites, too.
7043 It is not recommended to use this filter as a default.
7049 <term><emphasis>jumping-windows</emphasis></term>
7052 Many consider windows that move, or resize themselves to be abusive. This filter
7053 neutralizes the related JavaScript code. Note that some sites might not display
7054 or behave as intended when using this filter. Use with caution.
7060 <term><emphasis>frameset-borders</emphasis></term>
7063 Some web designers seem to assume that everyone in the world will view their
7064 web sites using the same browser brand and version, screen resolution etc,
7065 because only that assumption could explain why they'd use static frame sizes,
7066 yet prevent their frames from being resized by the user, should they be too
7067 small to show their whole content.
7070 This filter removes the related HTML code. It should only be applied to sites
7077 <term><emphasis>demoronizer</emphasis></term>
7080 Many Microsoft products that generate HTML use non-standard extensions (read:
7081 violations) of the ISO 8859-1 aka Latin-1 character set. This can cause those
7082 HTML documents to display with errors on standard-compliant platforms.
7085 This filter translates the MS-only characters into Latin-1 equivalents.
7086 It is not necessary when using MS products, and will cause corruption of
7087 all documents that use 8-bit character sets other than Latin-1. It's mostly
7088 worthwhile for Europeans on non-MS platforms, if weird garbage characters
7089 sometimes appear on some pages, or user agents that don't correct for this on
7092 My version of Mozilla (ancient) shows litte square boxes for quote
7093 characters, and apostrophes on moronized pages. So many pages have this, I
7094 can read them fine now. HB 08/27/06
7101 <term><emphasis>shockwave-flash</emphasis></term>
7104 A filter for shockwave haters. As the name suggests, this filter strips code
7105 out of web pages that is used to embed shockwave flash objects.
7113 <term><emphasis>quicktime-kioskmode</emphasis></term>
7116 Change HTML code that embeds Quicktime objects so that kioskmode, which
7117 prevents saving, is disabled.
7123 <term><emphasis>fun</emphasis></term>
7126 Text replacements for subversive browsing fun. Make fun of your favorite
7127 Monopolist or play buzzword bingo.
7133 <term><emphasis>crude-parental</emphasis></term>
7136 A demonstration-only filter that shows how <application>Privoxy</application>
7137 can be used to delete web content on a keyword basis.
7143 <term><emphasis>ie-exploits</emphasis></term>
7146 An experimental collection of text replacements to disable malicious HTML and JavaScript
7147 code that exploits known security holes in Internet Explorer.
7150 Presently, it only protects against Nimda and a cross-site scripting bug, and
7151 would need active maintenance to provide more substantial protection.
7157 <term><emphasis>site-specifics</emphasis></term>
7160 Some web sites have very specific problems, the cure for which doesn't apply
7161 anywhere else, or could even cause damage on other sites.
7164 This is a collection of such site-specific cures which should only be applied
7165 to the sites they were intended for, which is what the supplied
7166 <filename>default.action</filename> file does. Users shouldn't need to change
7167 anything regarding this filter.
7173 <term><emphasis>google</emphasis></term>
7176 A CSS based block for Google text ads. Also removes a width limitation
7177 and the toolbar advertisement.
7183 <term><emphasis>yahoo</emphasis></term>
7186 Another CSS based block, this time for Yahoo text ads. And removes
7187 a width limitation as well.
7193 <term><emphasis>msn</emphasis></term>
7196 Another CSS based block, this time for MSN text ads. And removes
7197 tracking URLs, as well as a width limitation.
7203 <term><emphasis>blogspot</emphasis></term>
7206 Cleans up some Blogspot blogs. Read the fine print before using this one!
7209 This filter also intentionally removes some navigation stuff and sets the
7210 page width to 100%. As a result, some rounded <quote>corners</quote> would
7211 appear to early or not at all and as fixing this would require a browser
7212 that understands background-size (CSS3), they are removed instead.
7218 <term><emphasis>xml-to-html</emphasis></term>
7221 Server-header filter to change the Content-Type from xml to html.
7227 <term><emphasis>html-to-xml</emphasis></term>
7230 Server-header filter to change the Content-Type from html to xml.
7236 <term><emphasis>no-ping</emphasis></term>
7239 Removes the non-standard <literal>ping</literal> attribute from
7240 anchor and area HTML tags.
7246 <term><emphasis>hide-tor-exit-notation</emphasis></term>
7249 Client-header filter to remove the <command>Tor</command> exit node notation
7250 found in Host and Referer headers.
7253 If &my-app; and <command>Tor</command> are chained and &my-app;
7254 is configured to use socks4a, one can use <quote>http://www.example.org.foobar.exit/</quote>
7255 to access the host <quote>www.example.org</quote> through the
7256 <command>Tor</command> exit node <quote>foobar</quote>.
7259 As the HTTP client isn't aware of this notation, it treats the
7260 whole string <quote>www.example.org.foobar.exit</quote> as host and uses it
7261 for the <quote>Host</quote> and <quote>Referer</quote> headers. From the
7262 server's point of view the resulting headers are invalid and can cause problems.
7265 An invalid <quote>Referer</quote> header can trigger <quote>hot-linking</quote>
7266 protections, an invalid <quote>Host</quote> header will make it impossible for
7267 the server to find the right vhost (several domains hosted on the same IP address).
7270 This client-header filter removes the <quote>foo.exit</quote> part in those headers
7271 to prevent the mentioned problems. Note that it only modifies
7272 the HTTP headers, it doesn't make it impossible for the server
7273 to detect your <command>Tor</command> exit node based on the IP address
7274 the request is coming from.
7281 <term><emphasis> </emphasis></term>
7295 <!-- ~ End section ~ -->
7299 <!-- ~~~~~ New section ~~~~~ -->
7301 <sect1 id="templates">
7302 <title>Privoxy's Template Files</title>
7304 All <application>Privoxy</application> built-in pages, i.e. error pages such as the
7305 <ulink url="http://show-the-404-error.page"><quote>404 - No Such Domain</quote>
7306 error page</ulink>, the <ulink
7307 url="http://ads.bannerserver.example.com/nasty-ads/sponsor.html"><quote>BLOCKED</quote>
7309 and all pages of its <ulink url="http://config.privoxy.org/">web-based
7310 user interface</ulink>, are generated from <emphasis>templates</emphasis>.
7311 (<application>Privoxy</application> must be running for the above links to work as
7316 These templates are stored in a subdirectory of the <link linkend="confdir">configuration
7317 directory</link> called <filename>templates</filename>. On Unixish platforms,
7319 <ulink url="file:///etc/privoxy/templates/"><filename>/etc/privoxy/templates/</filename></ulink>.
7323 The templates are basically normal HTML files, but with place-holders (called symbols
7324 or exports), which <application>Privoxy</application> fills at run time. It
7325 is possible to edit the templates with a normal text editor, should you want
7326 to customize them. (<emphasis>Not recommended for the casual
7327 user</emphasis>). Should you create your own custom templates, you should use
7328 the <filename>config</filename> setting <link linkend="templdir">templdir</link>
7329 to specify an alternate location, so your templates do not get overwritten
7333 Note that just like in configuration files, lines starting
7334 with <literal>#</literal> are ignored when the templates are filled in.
7338 The place-holders are of the form <literal>@name@</literal>, and you will
7339 find a list of available symbols, which vary from template to template,
7340 in the comments at the start of each file. Note that these comments are not
7341 always accurate, and that it's probably best to look at the existing HTML
7342 code to find out which symbols are supported and what they are filled in with.
7346 A special application of this substitution mechanism is to make whole
7347 blocks of HTML code disappear when a specific symbol is set. We use this
7348 for many purposes, one of them being to include the beta warning in all
7349 our user interface (CGI) pages when <application>Privoxy</application>
7350 is in an alpha or beta development stage:
7355 <!-- @if-unstable-start -->
7357 ... beta warning HTML code goes here ...
7359 <!-- if-unstable-end@ --></screen>
7363 If the "unstable" symbol is set, everything in between and including
7364 <literal>@if-unstable-start</literal> and <literal>if-unstable-end@</literal>
7365 will disappear, leaving nothing but an empty comment:
7369 <screen><!-- --></screen>
7373 There's also an if-then-else construct and an <literal>#include</literal>
7374 mechanism, but you'll sure find out if you are inclined to edit the
7379 All templates refer to a style located at
7380 <ulink url="http://config.privoxy.org/send-stylesheet"><literal>http://config.privoxy.org/send-stylesheet</literal></ulink>.
7381 This is, of course, locally served by <application>Privoxy</application>
7382 and the source for it can be found and edited in the
7383 <filename>cgi-style.css</filename> template.
7388 <!-- ~ End section ~ -->
7392 <!-- ~~~~~ New section ~~~~~ -->
7394 <sect1 id="contact"><title>Contacting the Developers, Bug Reporting and Feature
7397 <!-- Include contacting.sgml boilerplate: -->
7399 <!-- end boilerplate -->
7403 <!-- ~ End section ~ -->
7406 <!-- ~~~~~ New section ~~~~~ -->
7407 <sect1 id="copyright"><title>Privoxy Copyright, License and History</title>
7409 <!-- Include copyright.sgml: -->
7411 <!-- end copyright -->
7414 <application>Privoxy</application> is free software; you can
7415 redistribute it and/or modify it under the terms of the
7416 <citetitle>GNU General Public License</citetitle>, version 2,
7417 as published by the Free Software Foundation and included in
7421 <!-- ~~~~~ New section ~~~~~ -->
7422 <sect2 id="license"><title>License</title>
7424 <screen><![ RCDATA [ &GPLv2; ]]></screen>
7428 <!-- ~ End section ~ -->
7431 <!-- ~~~~~ New section ~~~~~ -->
7433 <sect2 id="history"><title>History</title>
7434 <!-- Include history.sgml: -->
7436 <!-- end history -->
7439 <sect2 id="authors"><title>Authors</title>
7440 <!-- Include p-authors.sgml: -->
7442 <!-- end authors -->
7447 <!-- ~ End section ~ -->
7450 <!-- ~~~~~ New section ~~~~~ -->
7451 <sect1 id="seealso"><title>See Also</title>
7452 <!-- Include seealso.sgml: -->
7454 <!-- end seealso -->
7459 <!-- ~~~~~ New section ~~~~~ -->
7460 <sect1 id="appendix"><title>Appendix</title>
7463 <!-- ~~~~~ New section ~~~~~ -->
7465 <title>Regular Expressions</title>
7467 <application>Privoxy</application> uses Perl-style <quote>regular
7468 expressions</quote> in its <link linkend="actions-file">actions
7469 files</link> and <link linkend="filter-file">filter file</link>,
7470 through the <ulink url="http://www.pcre.org/">PCRE</ulink> and
7473 <ulink url="http://www.oesterhelt.org/pcrs/">PCRS</ulink> libraries.
7475 <application>PCRS</application> libraries.
7479 If you are reading this, you probably don't understand what <quote>regular
7480 expressions</quote> are, or what they can do. So this will be a very brief
7481 introduction only. A full explanation would require a <ulink
7482 url="http://www.oreilly.com/catalog/regex/">book</ulink> ;-)
7486 Regular expressions provide a language to describe patterns that can be
7487 run against strings of characters (letter, numbers, etc), to see if they
7488 match the string or not. The patterns are themselves (sometimes complex)
7489 strings of literal characters, combined with wild-cards, and other special
7490 characters, called meta-characters. The <quote>meta-characters</quote> have
7491 special meanings and are used to build complex patterns to be matched against.
7492 Perl Compatible Regular Expressions are an especially convenient
7493 <quote>dialect</quote> of the regular expression language.
7497 To make a simple analogy, we do something similar when we use wild-card
7498 characters when listing files with the <command>dir</command> command in DOS.
7499 <literal>*.*</literal> matches all filenames. The <quote>special</quote>
7500 character here is the asterisk which matches any and all characters. We can be
7501 more specific and use <literal>?</literal> to match just individual
7502 characters. So <quote>dir file?.text</quote> would match
7503 <quote>file1.txt</quote>, <quote>file2.txt</quote>, etc. We are pattern
7504 matching, using a similar technique to <quote>regular expressions</quote>!
7508 Regular expressions do essentially the same thing, but are much, much more
7509 powerful. There are many more <quote>special characters</quote> and ways of
7510 building complex patterns however. Let's look at a few of the common ones,
7511 and then some examples:
7516 <emphasis>.</emphasis> - Matches any single character, e.g. <quote>a</quote>,
7517 <quote>A</quote>, <quote>4</quote>, <quote>:</quote>, or <quote>@</quote>.
7519 </simplelist></para>
7523 <emphasis>?</emphasis> - The preceding character or expression is matched ZERO or ONE
7526 </simplelist></para>
7530 <emphasis>+</emphasis> - The preceding character or expression is matched ONE or MORE
7533 </simplelist></para>
7537 <emphasis>*</emphasis> - The preceding character or expression is matched ZERO or MORE
7540 </simplelist></para>
7544 <emphasis>\</emphasis> - The <quote>escape</quote> character denotes that
7545 the following character should be taken literally. This is used where one of the
7546 special characters (e.g. <quote>.</quote>) needs to be taken literally and
7547 not as a special meta-character. Example: <quote>example\.com</quote>, makes
7548 sure the period is recognized only as a period (and not expanded to its
7549 meta-character meaning of any single character).
7551 </simplelist></para>
7555 <emphasis>[ ]</emphasis> - Characters enclosed in brackets will be matched if
7556 any of the enclosed characters are encountered. For instance, <quote>[0-9]</quote>
7557 matches any numeric digit (zero through nine). As an example, we can combine
7558 this with <quote>+</quote> to match any digit one of more times: <quote>[0-9]+</quote>.
7560 </simplelist></para>
7564 <emphasis>( )</emphasis> - parentheses are used to group a sub-expression,
7565 or multiple sub-expressions.
7567 </simplelist></para>
7571 <emphasis>|</emphasis> - The <quote>bar</quote> character works like an
7572 <quote>or</quote> conditional statement. A match is successful if the
7573 sub-expression on either side of <quote>|</quote> matches. As an example:
7574 <quote>/(this|that) example/</quote> uses grouping and the bar character
7575 and would match either <quote>this example</quote> or <quote>that
7576 example</quote>, and nothing else.
7578 </simplelist></para>
7581 These are just some of the ones you are likely to use when matching URLs with
7582 <application>Privoxy</application>, and is a long way from a definitive
7583 list. This is enough to get us started with a few simple examples which may
7584 be more illuminating:
7588 <emphasis><literal>/.*/banners/.*</literal></emphasis> - A simple example
7589 that uses the common combination of <quote>.</quote> and <quote>*</quote> to
7590 denote any character, zero or more times. In other words, any string at all.
7591 So we start with a literal forward slash, then our regular expression pattern
7592 (<quote>.*</quote>) another literal forward slash, the string
7593 <quote>banners</quote>, another forward slash, and lastly another
7594 <quote>.*</quote>. We are building
7595 a directory path here. This will match any file with the path that has a
7596 directory named <quote>banners</quote> in it. The <quote>.*</quote> matches
7597 any characters, and this could conceivably be more forward slashes, so it
7598 might expand into a much longer looking path. For example, this could match:
7599 <quote>/eye/hate/spammers/banners/annoy_me_please.gif</quote>, or just
7600 <quote>/banners/annoying.html</quote>, or almost an infinite number of other
7601 possible combinations, just so it has <quote>banners</quote> in the path
7606 And now something a little more complex:
7610 <emphasis><literal>/.*/adv((er)?ts?|ertis(ing|ements?))?/</literal></emphasis> -
7611 We have several literal forward slashes again (<quote>/</quote>), so we are
7612 building another expression that is a file path statement. We have another
7613 <quote>.*</quote>, so we are matching against any conceivable sub-path, just so
7614 it matches our expression. The only true literal that <emphasis>must
7615 match</emphasis> our pattern is <application>adv</application>, together with
7616 the forward slashes. What comes after the <quote>adv</quote> string is the
7621 Remember the <quote>?</quote> means the preceding expression (either a
7622 literal character or anything grouped with <quote>(...)</quote> in this case)
7623 can exist or not, since this means either zero or one match. So
7624 <quote>((er)?ts?|ertis(ing|ements?))</quote> is optional, as are the
7625 individual sub-expressions: <quote>(er)</quote>,
7626 <quote>(ing|ements?)</quote>, and the <quote>s</quote>. The <quote>|</quote>
7627 means <quote>or</quote>. We have two of those. For instance,
7628 <quote>(ing|ements?)</quote>, can expand to match either <quote>ing</quote>
7629 <emphasis>OR</emphasis> <quote>ements?</quote>. What is being done here, is an
7630 attempt at matching as many variations of <quote>advertisement</quote>, and
7631 similar, as possible. So this would expand to match just <quote>adv</quote>,
7632 or <quote>advert</quote>, or <quote>adverts</quote>, or
7633 <quote>advertising</quote>, or <quote>advertisement</quote>, or
7634 <quote>advertisements</quote>. You get the idea. But it would not match
7635 <quote>advertizements</quote> (with a <quote>z</quote>). We could fix that by
7636 changing our regular expression to:
7637 <quote>/.*/adv((er)?ts?|erti(s|z)(ing|ements?))?/</quote>, which would then match
7642 <emphasis><literal>/.*/advert[0-9]+\.(gif|jpe?g)</literal></emphasis> - Again
7643 another path statement with forward slashes. Anything in the square brackets
7644 <quote>[ ]</quote> can be matched. This is using <quote>0-9</quote> as a
7645 shorthand expression to mean any digit one through nine. It is the same as
7646 saying <quote>0123456789</quote>. So any digit matches. The <quote>+</quote>
7647 means one or more of the preceding expression must be included. The preceding
7648 expression here is what is in the square brackets -- in this case, any digit
7649 one through nine. Then, at the end, we have a grouping: <quote>(gif|jpe?g)</quote>.
7650 This includes a <quote>|</quote>, so this needs to match the expression on
7651 either side of that bar character also. A simple <quote>gif</quote> on one side, and the other
7652 side will in turn match either <quote>jpeg</quote> or <quote>jpg</quote>,
7653 since the <quote>?</quote> means the letter <quote>e</quote> is optional and
7654 can be matched once or not at all. So we are building an expression here to
7655 match image GIF or JPEG type image file. It must include the literal
7656 string <quote>advert</quote>, then one or more digits, and a <quote>.</quote>
7657 (which is now a literal, and not a special character, since it is escaped
7658 with <quote>\</quote>), and lastly either <quote>gif</quote>, or
7659 <quote>jpeg</quote>, or <quote>jpg</quote>. Some possible matches would
7660 include: <quote>//advert1.jpg</quote>,
7661 <quote>/nasty/ads/advert1234.gif</quote>,
7662 <quote>/banners/from/hell/advert99.jpg</quote>. It would not match
7663 <quote>advert1.gif</quote> (no leading slash), or
7664 <quote>/adverts232.jpg</quote> (the expression does not include an
7665 <quote>s</quote>), or <quote>/advert1.jsp</quote> (<quote>jsp</quote> is not
7666 in the expression anywhere).
7670 We are barely scratching the surface of regular expressions here so that you
7671 can understand the default <application>Privoxy</application>
7672 configuration files, and maybe use this knowledge to customize your own
7673 installation. There is much, much more that can be done with regular
7674 expressions. Now that you know enough to get started, you can learn more on
7679 More reading on Perl Compatible Regular expressions:
7680 <ulink url="http://perldoc.perl.org/perlre.html">http://perldoc.perl.org/perlre.html</ulink>
7684 For information on regular expression based substitutions and their applications
7685 in filters, please see the <link linkend="filter-file">filter file tutorial</link>
7690 <!-- ~ End section ~ -->
7693 <!-- ~~~~~ New section ~~~~~ -->
7695 <title>Privoxy's Internal Pages</title>
7698 Since <application>Privoxy</application> proxies each requested
7699 web page, it is easy for <application>Privoxy</application> to
7700 trap certain special URLs. In this way, we can talk directly to
7701 <application>Privoxy</application>, and see how it is
7702 configured, see how our rules are being applied, change these
7703 rules and other configuration options, and even turn
7704 <application>Privoxy's</application> filtering off, all with
7710 The URLs listed below are the special ones that allow direct access
7711 to <application>Privoxy</application>. Of course,
7712 <application>Privoxy</application> must be running to access these. If
7713 not, you will get a friendly error message. Internet access is not
7726 <ulink url="http://config.privoxy.org/">http://config.privoxy.org/</ulink>
7730 There is a shortcut: <ulink url="http://p.p/">http://p.p/</ulink> (But it
7731 doesn't provide a fall-back to a real page, in case the request is not
7732 sent through <application>Privoxy</application>)
7738 Show information about the current configuration, including viewing and
7739 editing of actions files:
7743 <ulink url="http://config.privoxy.org/show-status">http://config.privoxy.org/show-status</ulink>
7750 Show the source code version numbers:
7754 <ulink url="http://config.privoxy.org/show-version">http://config.privoxy.org/show-version</ulink>
7761 Show the browser's request headers:
7765 <ulink url="http://config.privoxy.org/show-request">http://config.privoxy.org/show-request</ulink>
7772 Show which actions apply to a URL and why:
7776 <ulink url="http://config.privoxy.org/show-url-info">http://config.privoxy.org/show-url-info</ulink>
7783 Toggle Privoxy on or off. This feature can be turned off/on in the main
7784 <filename>config</filename> file. When toggled <quote>off</quote>, <quote>Privoxy</quote>
7785 continues to run, but only as a pass-through proxy, with no actions taking
7790 <ulink url="http://config.privoxy.org/toggle">http://config.privoxy.org/toggle</ulink>
7794 Short cuts. Turn off, then on:
7798 <ulink url="http://config.privoxy.org/toggle?set=disable">http://config.privoxy.org/toggle?set=disable</ulink>
7803 <ulink url="http://config.privoxy.org/toggle?set=enable">http://config.privoxy.org/toggle?set=enable</ulink>
7812 These may be bookmarked for quick reference. See next.
7816 <sect3 id="bookmarklets">
7817 <title>Bookmarklets</title>
7819 Below are some <quote>bookmarklets</quote> to allow you to easily access a
7820 <quote>mini</quote> version of some of <application>Privoxy's</application>
7821 special pages. They are designed for MS Internet Explorer, but should work
7822 equally well in Netscape, Mozilla, and other browsers which support
7823 JavaScript. They are designed to run directly from your bookmarks - not by
7824 clicking the links below (although that should work for testing).
7827 To save them, right-click the link and choose <quote>Add to Favorites</quote>
7828 (IE) or <quote>Add Bookmark</quote> (Netscape). You will get a warning that
7829 the bookmark <quote>may not be safe</quote> - just click OK. Then you can run the
7830 Bookmarklet directly from your favorites/bookmarks. For even faster access,
7831 you can put them on the <quote>Links</quote> bar (IE) or the <quote>Personal
7832 Toolbar</quote> (Netscape), and run them with a single click.
7841 url="javascript:void(window.open('http://config.privoxy.org/toggle?mini=y&set=enabled','ijbstatus','width=250,height=100,resizable=yes,scrollbars=no,toolbar=no,location=no,directories=no,status=no,menubar=no,copyhistory=no').focus());">Privoxy - Enable</ulink>
7848 url="javascript:void(window.open('http://config.privoxy.org/toggle?mini=y&set=disabled','ijbstatus','width=250,height=100,resizable=yes,scrollbars=no,toolbar=no,location=no,directories=no,status=no,menubar=no,copyhistory=no').focus());">Privoxy - Disable</ulink>
7855 url="javascript:void(window.open('http://config.privoxy.org/toggle?mini=y&set=toggle','ijbstatus','width=250,height=100,resizable=yes,scrollbars=no,toolbar=no,location=no,directories=no,status=no,menubar=no,copyhistory=no').focus());">Privoxy - Toggle Privoxy</ulink> (Toggles between enabled and disabled)
7862 url="javascript:void(window.open('http://config.privoxy.org/toggle?mini=y','ijbstatus','width=250,height=2,resizable=yes,scrollbars=no,toolbar=no,location=no,directories=no,status=no,menubar=no,copyhistory=no').focus());">Privoxy- View Status</ulink>
7868 <ulink url="javascript:w=Math.floor(screen.width/2);h=Math.floor(screen.height*0.9);void(window.open('http://www.privoxy.org/actions/index.php?url='+escape(location.href),'Feedback','screenx='+w+',width='+w+',height='+h+',scrollbars=yes,toolbar=no,location=no,directories=no,status=no,menubar=no,copyhistory=no').focus());">Privoxy - Submit Actions File Feedback</ulink>
7874 <ulink url="javascript:void(window.open('http://config.privoxy.org/show-url-info?url='+escape(location.href),'Why').focus());">Privoxy - Why?</ulink>
7881 Credit: The site which gave us the general idea for these bookmarklets is
7882 <ulink url="http://www.bookmarklets.com/">www.bookmarklets.com</ulink>. They
7883 have more information about bookmarklets.
7892 <!-- ~~~~~ New section ~~~~~ -->
7894 <title>Chain of Events</title>
7896 Let's take a quick look at how some of <application>Privoxy's</application>
7897 core features are triggered, and the ensuing sequence of events when a web
7898 page is requested by your browser:
7905 First, your web browser requests a web page. The browser knows to send
7906 the request to <application>Privoxy</application>, which will in turn,
7907 relay the request to the remote web server after passing the following
7913 <application>Privoxy</application> traps any request for its own internal CGI
7914 pages (e.g <ulink url="http://p.p/">http://p.p/</ulink>) and sends the CGI page back to the browser.
7919 Next, <application>Privoxy</application> checks to see if the URL
7921 linkend="BLOCK"><quote>+block</quote></link> patterns. If
7922 so, the URL is then blocked, and the remote web server will not be contacted.
7923 <link linkend="HANDLE-AS-IMAGE"><quote>+handle-as-image</quote></link>
7925 <link linkend="HANDLE-AS-EMPTY-DOCUMENT"><quote>+handle-as-empty-document</quote></link>
7926 are then checked, and if there is no match, an
7927 HTML <quote>BLOCKED</quote> page is sent back to the browser. Otherwise, if
7928 it does match, an image is returned for the former, and an empty text
7929 document for the latter. The type of image would depend on the setting of
7930 <link linkend="SET-IMAGE-BLOCKER"><quote>+set-image-blocker</quote></link>
7931 (blank, checkerboard pattern, or an HTTP redirect to an image elsewhere).
7936 Untrusted URLs are blocked. If URLs are being added to the
7937 <filename>trust</filename> file, then that is done.
7942 If the URL pattern matches the <link
7943 linkend="FAST-REDIRECTS"><quote>+fast-redirects</quote></link> action,
7944 it is then processed. Unwanted parts of the requested URL are stripped.
7949 Now the rest of the client browser's request headers are processed. If any
7950 of these match any of the relevant actions (e.g. <link
7951 linkend="HIDE-USER-AGENT"><quote>+hide-user-agent</quote></link>,
7952 etc.), headers are suppressed or forged as determined by these actions and
7958 Now the web server starts sending its response back (i.e. typically a web
7964 First, the server headers are read and processed to determine, among other
7965 things, the MIME type (document type) and encoding. The headers are then
7966 filtered as determined by the
7967 <link linkend="CRUNCH-INCOMING-COOKIES"><quote>+crunch-incoming-cookies</quote></link>,
7968 <link linkend="SESSION-COOKIES-ONLY"><quote>+session-cookies-only</quote></link>,
7969 and <link linkend="DOWNGRADE-HTTP-VERSION"><quote>+downgrade-http-version</quote></link>
7975 If any <link linkend="FILTER"><quote>+filter</quote></link> action
7977 linkend="DEANIMATE-GIFS"><quote>+deanimate-gifs</quote></link>
7978 action applies (and the document type fits the action), the rest of the page is
7979 read into memory (up to a configurable limit). Then the filter rules (from
7980 <filename>default.filter</filename> and any other filter files) are
7981 processed against the buffered content. Filters are applied in the order
7982 they are specified in one of the filter files. Animated GIFs, if present,
7983 are reduced to either the first or last frame, depending on the action
7984 setting.The entire page, which is now filtered, is then sent by
7985 <application>Privoxy</application> back to your browser.
7988 If neither a <link linkend="FILTER"><quote>+filter</quote></link> action
7990 linkend="DEANIMATE-GIFS"><quote>+deanimate-gifs</quote></link>
7991 matches, then <application>Privoxy</application> passes the raw data through
7992 to the client browser as it becomes available.
7997 As the browser receives the now (possibly filtered) page content, it
7998 reads and then requests any URLs that may be embedded within the page
7999 source, e.g. ad images, stylesheets, JavaScript, other HTML documents (e.g.
8000 frames), sounds, etc. For each of these objects, the browser issues a
8001 separate request (this is easily viewable in <application>Privoxy's</application>
8002 logs). And each such request is in turn processed just as above. Note that a
8003 complex web page will have many, many such embedded URLs. If these
8004 secondary requests are to a different server, then quite possibly a very
8005 differing set of actions is triggered.
8012 NOTE: This is somewhat of a simplistic overview of what happens with each URL
8013 request. For the sake of brevity and simplicity, we have focused on
8014 <application>Privoxy's</application> core features only.
8020 <!-- ~~~~~ New section ~~~~~ -->
8021 <sect2 id="actionsanat">
8022 <title>Troubleshooting: Anatomy of an Action</title>
8025 The way <application>Privoxy</application> applies
8026 <link linkend="ACTIONS">actions</link> and <link linkend="FILTER">filters</link>
8027 to any given URL can be complex, and not always so
8028 easy to understand what is happening. And sometimes we need to be able to
8029 <emphasis>see</emphasis> just what <application>Privoxy</application> is
8030 doing. Especially, if something <application>Privoxy</application> is doing
8031 is causing us a problem inadvertently. It can be a little daunting to look at
8032 the actions and filters files themselves, since they tend to be filled with
8033 <link linkend="regex">regular expressions</link> whose consequences are not
8038 One quick test to see if <application>Privoxy</application> is causing a problem
8039 or not, is to disable it temporarily. This should be the first troubleshooting
8040 step. See <link linkend="bookmarklets">the Bookmarklets</link> section on a quick
8041 and easy way to do this (be sure to flush caches afterward!). Looking at the
8042 logs is a good idea too. (Note that both the toggle feature and logging are
8043 enabled via <filename>config</filename> file settings, and may need to be
8044 turned <quote>on</quote>.)
8047 Another easy troubleshooting step to try is if you have done any
8048 customization of your installation, revert back to the installed
8049 defaults and see if that helps. There are times the developers get complaints
8050 about one thing or another, and the problem is more related to a customized
8051 configuration issue.
8055 <application>Privoxy</application> also provides the
8056 <ulink url="http://config.privoxy.org/show-url-info">http://config.privoxy.org/show-url-info</ulink>
8057 page that can show us very specifically how <application>actions</application>
8058 are being applied to any given URL. This is a big help for troubleshooting.
8062 First, enter one URL (or partial URL) at the prompt, and then
8063 <application>Privoxy</application> will tell us
8064 how the current configuration will handle it. This will not
8065 help with filtering effects (i.e. the <link
8066 linkend="FILTER"><quote>+filter</quote></link> action) from
8067 one of the filter files since this is handled very
8068 differently and not so easy to trap! It also will not tell you about any other
8069 URLs that may be embedded within the URL you are testing. For instance, images
8070 such as ads are expressed as URLs within the raw page source of HTML pages. So
8071 you will only get info for the actual URL that is pasted into the prompt area
8072 -- not any sub-URLs. If you want to know about embedded URLs like ads, you
8073 will have to dig those out of the HTML source. Use your browser's <quote>View
8074 Page Source</quote> option for this. Or right click on the ad, and grab the
8079 Let's try an example, <ulink url="http://google.com">google.com</ulink>,
8080 and look at it one section at a time in a sample configuration (your real
8081 configuration may vary):
8086 Matches for http://www.google.com:
8088 In file: default.action <guibutton>[ View ]</guibutton> <guibutton>[ Edit ]</guibutton>
8090 {+change-x-forwarded-for{block}
8091 +deanimate-gifs {last}
8092 +fast-redirects {check-decoded-url}
8093 +filter {refresh-tags}
8094 +filter {img-reorder}
8095 +filter {banners-by-size}
8097 +filter {jumping-windows}
8098 +filter {ie-exploits}
8099 +hide-from-header {block}
8100 +hide-referrer {forge}
8101 +session-cookies-only
8102 +set-image-blocker {pattern}
8105 { -session-cookies-only }
8111 In file: user.action <guibutton>[ View ]</guibutton> <guibutton>[ Edit ]</guibutton>
8112 (no matches in this file)
8117 This is telling us how we have defined our
8118 <link linkend="ACTIONS"><quote>actions</quote></link>, and
8119 which ones match for our test case, <quote>google.com</quote>.
8120 Displayed is all the actions that are available to us. Remember,
8121 the <literal>+</literal> sign denotes <quote>on</quote>. <literal>-</literal>
8122 denotes <quote>off</quote>. So some are <quote>on</quote> here, but many
8123 are <quote>off</quote>. Each example we try may provide a slightly different
8124 end result, depending on our configuration directives.
8128 is for our <filename>default.action</filename> file. The large, multi-line
8129 listing, is how the actions are set to match for all URLs, i.e. our default
8130 settings. If you look at your <quote>actions</quote> file, this would be the
8131 section just below the <quote>aliases</quote> section near the top. This
8132 will apply to all URLs as signified by the single forward slash at the end
8133 of the listing -- <quote> / </quote>.
8137 But we have defined additional actions that would be exceptions to these general
8138 rules, and then we list specific URLs (or patterns) that these exceptions
8139 would apply to. Last match wins. Just below this then are two explicit
8140 matches for <quote>.google.com</quote>. The first is negating our previous
8141 cookie setting, which was for <link
8142 linkend="SESSION-COOKIES-ONLY"><quote>+session-cookies-only</quote></link>
8143 (i.e. not persistent). So we will allow persistent cookies for google, at
8144 least that is how it is in this example. The second turns
8145 <emphasis>off</emphasis> any <link
8146 linkend="FAST-REDIRECTS"><quote>+fast-redirects</quote></link>
8147 action, allowing this to take place unmolested. Note that there is a leading
8148 dot here -- <quote>.google.com</quote>. This will match any hosts and
8149 sub-domains, in the google.com domain also, such as
8150 <quote>www.google.com</quote> or <quote>mail.google.com</quote>. But it would not
8151 match <quote>www.google.de</quote>! So, apparently, we have these two actions
8152 defined as exceptions to the general rules at the top somewhere in the lower
8153 part of our <filename>default.action</filename> file, and
8154 <quote>google.com</quote> is referenced somewhere in these latter sections.
8158 Then, for our <filename>user.action</filename> file, we again have no hits.
8159 So there is nothing google-specific that we might have added to our own, local
8160 configuration. If there was, those actions would over-rule any actions from
8161 previously processed files, such as <filename>default.action</filename>.
8162 <filename>user.action</filename> typically has the last word. This is the
8163 best place to put hard and fast exceptions,
8167 And finally we pull it all together in the bottom section and summarize how
8168 <application>Privoxy</application> is applying all its <quote>actions</quote>
8169 to <quote>google.com</quote>:
8180 +change-x-forwarded-for{block}
8181 -client-header-filter{hide-tor-exit-notation}
8182 -content-type-overwrite
8183 -crunch-client-header
8184 -crunch-if-none-match
8185 -crunch-incoming-cookies
8186 -crunch-outgoing-cookies
8187 -crunch-server-header
8188 +deanimate-gifs {last}
8189 -downgrade-http-version
8192 -filter {content-cookies}
8193 -filter {all-popups}
8194 -filter {banners-by-link}
8195 -filter {tiny-textforms}
8196 -filter {frameset-borders}
8197 -filter {demoronizer}
8198 -filter {shockwave-flash}
8199 -filter {quicktime-kioskmode}
8201 -filter {crude-parental}
8202 -filter {site-specifics}
8203 -filter {js-annoyances}
8204 -filter {html-annoyances}
8205 +filter {refresh-tags}
8206 -filter {unsolicited-popups}
8207 +filter {img-reorder}
8208 +filter {banners-by-size}
8210 +filter {jumping-windows}
8211 +filter {ie-exploits}
8218 -handle-as-empty-document
8220 -hide-accept-language
8221 -hide-content-disposition
8222 +hide-from-header {block}
8223 -hide-if-modified-since
8224 +hide-referrer {forge}
8227 -overwrite-last-modified
8228 -prevent-compression
8230 -server-header-filter{xml-to-html}
8231 -server-header-filter{html-to-xml}
8232 -session-cookies-only
8233 +set-image-blocker {pattern} </screen>
8237 Notice the only difference here to the previous listing, is to
8238 <quote>fast-redirects</quote> and <quote>session-cookies-only</quote>,
8239 which are activated specifically for this site in our configuration,
8240 and thus show in the <quote>Final Results</quote>.
8244 Now another example, <quote>ad.doubleclick.net</quote>:
8250 { +block{Domains starts with "ad"} }
8253 { +block{Domain contains "ad"} }
8256 { +block{Doubleclick banner server} +handle-as-image }
8257 .[a-vx-z]*.doubleclick.net
8262 We'll just show the interesting part here - the explicit matches. It is
8263 matched three different times. Two <quote>+block{}</quote> sections,
8264 and a <quote>+block{} +handle-as-image</quote>,
8265 which is the expanded form of one of our aliases that had been defined as:
8266 <quote>+block-as-image</quote>. (<link
8267 linkend="ALIASES"><quote>Aliases</quote></link> are defined in
8268 the first section of the actions file and typically used to combine more
8273 Any one of these would have done the trick and blocked this as an unwanted
8274 image. This is unnecessarily redundant since the last case effectively
8275 would also cover the first. No point in taking chances with these guys
8276 though ;-) Note that if you want an ad or obnoxious
8277 URL to be invisible, it should be defined as <quote>ad.doubleclick.net</quote>
8278 is done here -- as both a <link
8279 linkend="BLOCK"><quote>+block{}</quote></link>
8280 <emphasis>and</emphasis> an
8281 <link linkend="HANDLE-AS-IMAGE"><quote>+handle-as-image</quote></link>.
8282 The custom alias <quote><literal>+block-as-image</literal></quote> just
8283 simplifies the process and make it more readable.
8287 One last example. Let's try <quote>http://www.example.net/adsl/HOWTO/</quote>.
8288 This one is giving us problems. We are getting a blank page. Hmmm ...
8294 Matches for http://www.example.net/adsl/HOWTO/:
8296 In file: default.action <guibutton>[ View ]</guibutton> <guibutton>[ Edit ]</guibutton>
8300 +change-x-forwarded-for{block}
8301 -client-header-filter{hide-tor-exit-notation}
8302 -content-type-overwrite
8303 -crunch-client-header
8304 -crunch-if-none-match
8305 -crunch-incoming-cookies
8306 -crunch-outgoing-cookies
8307 -crunch-server-header
8309 -downgrade-http-version
8310 +fast-redirects {check-decoded-url}
8312 -filter {content-cookies}
8313 -filter {all-popups}
8314 -filter {banners-by-link}
8315 -filter {tiny-textforms}
8316 -filter {frameset-borders}
8317 -filter {demoronizer}
8318 -filter {shockwave-flash}
8319 -filter {quicktime-kioskmode}
8321 -filter {crude-parental}
8322 -filter {site-specifics}
8323 -filter {js-annoyances}
8324 -filter {html-annoyances}
8325 +filter {refresh-tags}
8326 -filter {unsolicited-popups}
8327 +filter {img-reorder}
8328 +filter {banners-by-size}
8330 +filter {jumping-windows}
8331 +filter {ie-exploits}
8338 -handle-as-empty-document
8340 -hide-accept-language
8341 -hide-content-disposition
8342 +hide-from-header{block}
8343 +hide-referer{forge}
8345 -overwrite-last-modified
8346 +prevent-compression
8348 -server-header-filter{xml-to-html}
8349 -server-header-filter{html-to-xml}
8350 +session-cookies-only
8351 +set-image-blocker{blank} }
8354 { +block{Path contains "ads".} +handle-as-image }
8360 Ooops, the <quote>/adsl/</quote> is matching <quote>/ads</quote> in our
8361 configuration! But we did not want this at all! Now we see why we get the
8362 blank page. It is actually triggering two different actions here, and
8363 the effects are aggregated so that the URL is blocked, and &my-app; is told
8364 to treat the block as if it were an image. But this is, of course, all wrong.
8365 We could now add a new action below this (or better in our own
8366 <filename>user.action</filename> file) that explicitly
8367 <emphasis>un</emphasis> blocks (
8368 <link linkend="BLOCK"><quote>{-block}</quote></link>) paths with
8369 <quote>adsl</quote> in them (remember, last match in the configuration
8370 wins). There are various ways to handle such exceptions. Example:
8382 Now the page displays ;-)
8383 Remember to flush your browser's caches when making these kinds of changes to
8384 your configuration to insure that you get a freshly delivered page! Or, try
8385 using <literal>Shift+Reload</literal>.
8389 But now what about a situation where we get no explicit matches like
8396 { +block{Path starts with "ads".} +handle-as-image }
8402 That actually was very helpful and pointed us quickly to where the problem
8403 was. If you don't get this kind of match, then it means one of the default
8404 rules in the first section of <filename>default.action</filename> is causing
8405 the problem. This would require some guesswork, and maybe a little trial and
8406 error to isolate the offending rule. One likely cause would be one of the
8407 <link linkend="FILTER"><quote>+filter</quote></link> actions.
8408 These tend to be harder to troubleshoot.
8409 Try adding the URL for the site to one of aliases that turn off
8410 <link linkend="FILTER"><quote>+filter</quote></link>:
8418 .worldpay.com # for quietpc.com
8426 <quote><literal>{ shop }</literal></quote> is an <quote>alias</quote> that expands to
8427 <quote><literal>{ -filter -session-cookies-only }</literal></quote>.
8428 Or you could do your own exception to negate filtering:
8436 # Disable ALL filter actions for sites in this section
8444 This would turn off all filtering for these sites. This is best
8445 put in <filename>user.action</filename>, for local site
8446 exceptions. Note that when a simple domain pattern is used by itself (without
8447 the subsequent path portion), all sub-pages within that domain are included
8448 automatically in the scope of the action.
8452 Images that are inexplicably being blocked, may well be hitting the
8453 <link linkend="FILTER-BANNERS-BY-SIZE"><quote>+filter{banners-by-size}</quote></link>
8455 that images of certain sizes are ad banners (works well
8456 <emphasis>most of the time</emphasis> since these tend to be standardized).
8460 <quote><literal>{ fragile }</literal></quote> is an alias that disables most
8461 actions that are the most likely to cause trouble. This can be used as a
8462 last resort for problem sites.
8468 # Handle with care: easy to break
8470 mybank.example.com</screen>
8475 <emphasis>Remember to flush caches!</emphasis> Note that the
8476 <literal>mail.google</literal> reference lacks the TLD portion (e.g.
8477 <quote>.com</quote>). This will effectively match any TLD with
8478 <literal>google</literal> in it, such as <literal>mail.google.de.</literal>,
8482 If this still does not work, you will have to go through the remaining
8483 actions one by one to find which one(s) is causing the problem.
8492 This program is free software; you can redistribute it
8493 and/or modify it under the terms of the GNU General
8494 Public License as published by the Free Software
8495 Foundation; either version 2 of the License, or (at
8496 your option) any later version.
8498 This program is distributed in the hope that it will
8499 be useful, but WITHOUT ANY WARRANTY; without even the
8500 implied warranty of MERCHANTABILITY or FITNESS FOR A
8501 PARTICULAR PURPOSE. See the GNU General Public
8502 License for more details.
8504 The GNU General Public License should be included with
8505 this file. If not, you can view it at
8506 http://www.gnu.org/copyleft/gpl.html
8507 or write to the Free Software Foundation, Inc.,
8508 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,