1 <!DOCTYPE article PUBLIC "-//OASIS//DTD DocBook V3.1//EN" [
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3 <!entity supported SYSTEM "supported.sgml">
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5 <!entity p-intro SYSTEM "privoxy.sgml">
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10 <!entity copyright SYSTEM "copyright.sgml">
11 <!entity license SYSTEM "license.sgml">
12 <!entity GPLv2 SYSTEM "../../LICENSE">
13 <!entity p-authors SYSTEM "p-authors.sgml">
14 <!entity config SYSTEM "p-config.sgml">
15 <!entity changelog SYSTEM "changelog.sgml">
16 <!entity p-version "3.0.27">
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 -->
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24 <!entity % user-man "IGNORE">
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26 <!entity % p-supp-userman "IGNORE"> <!-- Omit some from supported.sgml -->
27 <!entity my-copy "©"> <!-- kludge for docbook2man -->
28 <!entity % draft "IGNORE"> <!-- WIP stuff -->
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30 <!entity my-app "<application>Privoxy</application>">
33 File : doc/source/user-manual.sgml
37 Copyright (C) 2001-2018 Privoxy Developers https://www.privoxy.org/
40 ========================================================================
41 NOTE: Please read developer-manual/documentation.html before touching
42 anything in this, or other Privoxy documentation.
43 ========================================================================
50 <title>Privoxy &p-version; User Manual</title>
54 <!-- Completely the wrong markup, but very little is allowed -->
55 <!-- in this part of an article. FIXME -->
56 <link linkend="copyright">Copyright</link> &my-copy; 2001-2017 by
57 <ulink url="https://www.privoxy.org/">Privoxy Developers</ulink>
63 Note: the following should generate a separate page, and a live link to it,
64 all nicely done. But it doesn't for some mysterious reason. Please leave
65 commented unless it can be fixed proper. For the time being, the
66 copyright/license declarations will be in their own sgml.
79 This is here to keep vim syntax file from breaking :/
80 If I knew enough to fix it, I would.
81 PLEASE DO NOT REMOVE! HB: hal@foobox.net
87 The <citetitle>Privoxy User Manual</citetitle> gives users information on how to
88 install, configure and use <ulink
89 url="https://www.privoxy.org/">Privoxy</ulink>.
92 <!-- Include privoxy.sgml boilerplate: -->
94 <!-- end privoxy.sgml -->
97 You can find the latest version of the <citetitle>Privoxy User Manual</citetitle> at <ulink
98 url="https://www.privoxy.org/user-manual/">https://www.privoxy.org/user-manual/</ulink>.
99 Please see the <link linkend="contact">Contact section</link> on how to
100 contact the developers.
107 <!-- ~~~~~ New section ~~~~~ -->
108 <sect1 label="1" id="introduction"><title>Introduction</title>
110 This documentation is included with the current &p-status; version of
111 <application>Privoxy</application>, &p-version;<![%p-not-stable;[,
112 and is mostly complete at this point. The most up to date reference for the
113 time being is still the comments in the source files and in the individual
114 configuration files. Development of a new version is currently nearing
115 completion, and includes significant changes and enhancements over
119 <!-- include only in non-stable versions -->
122 Since this is a &p-status; version, not all new features are well tested. This
123 documentation may be slightly out of sync as a result (especially with
124 CVS sources). And there <emphasis>may be</emphasis> bugs, though hopefully
129 <!-- ~~~~~ New section ~~~~~ -->
130 <sect2 id="features"><title>Features</title>
132 In addition to the core
133 features of ad blocking and
134 <ulink url="http://en.wikipedia.org/wiki/Browser_cookie">cookie</ulink> management,
135 <application>Privoxy</application> provides many supplemental
136 features<![%p-not-stable;[, some of them currently under development]]>,
137 that give the end-user more control, more privacy and more freedom:
139 <!-- Include newfeatures.sgml boilerplate here: -->
141 <!-- end boilerplate -->
146 <!-- ~ End section ~ -->
149 <!-- ~~~~~ New section ~~~~~ -->
150 <sect1 id="installation"><title>Installation</title>
153 <application>Privoxy</application> is available both in convenient pre-compiled
154 packages for a wide range of operating systems, and as raw source code.
155 For most users, we recommend using the packages, which can be downloaded from our
156 <ulink url="https://sourceforge.net/projects/ijbswa/">Privoxy Project
162 On some platforms, the installer may remove previously installed versions, if
163 found. (See below for your platform). In any case <emphasis>be sure to backup
164 your old configuration if it is valuable to you.</emphasis> See the <link
165 linkend="upgradersnote">note to upgraders</link> section below.
168 <!-- ~~~~~ New section ~~~~~ -->
169 <sect2 id="installation-packages"><title>Binary Packages</title>
171 How to install the binary packages depends on your operating system:
174 <!-- XXX: The installation sections should be sorted -->
176 <!-- ~~~~~ New section ~~~~~ -->
177 <sect3 id="installation-deb"><title>Debian and Ubuntu</title>
179 DEBs can be installed with <literal>apt-get install privoxy</literal>,
180 and will use <filename>/etc/privoxy</filename> for the location of
185 <!-- ~~~~~ New section ~~~~~ -->
186 <sect3 id="installation-pack-win"><title>Windows</title>
189 Just double-click the installer, which will guide you through
190 the installation process. You will find the configuration files
191 in the same directory as you installed <application>Privoxy</application> in.
194 Version 3.0.5 beta introduced full <application>Windows</application> service
195 functionality. On Windows only, the <application>Privoxy</application>
196 program has two new command line arguments to install and uninstall
197 <application>Privoxy</application> as a <emphasis>service</emphasis>.
201 <term>Arguments:</term>
204 <replaceable class="parameter">--install</replaceable>[:<replaceable class="parameter">service_name</replaceable>]
207 <replaceable class="parameter">--uninstall</replaceable>[:<replaceable class="parameter">service_name</replaceable>]
213 After invoking <application>Privoxy</application> with
214 <command>--install</command>, you will need to bring up the
215 <application>Windows</application> service console to assign the user you
216 want <application>Privoxy</application> to run under, and whether or not you
217 want it to run whenever the system starts. You can start the
218 <application>Windows</application> services console with the following
219 command: <command>services.msc</command>. If you do not take the manual step
220 of modifying <application>Privoxy's</application> service settings, it will
221 not start. Note too that you will need to give Privoxy a user account that
222 actually exists, or it will not be permitted to
223 write to its log and configuration files.
228 <!-- ~~~~~ New section ~~~~~ -->
229 <sect3 id="installation-os2"><title>OS/2</title>
232 First, make sure that no previous installations of
233 <application>Junkbuster</application> and / or
234 <application>Privoxy</application> are left on your
235 system. Check that no <application>Junkbuster</application>
236 or <application>Privoxy</application> objects are in
241 Then, just double-click the WarpIN self-installing archive, which will
242 guide you through the installation process. A shadow of the
243 <application>Privoxy</application> executable will be placed in your
244 startup folder so it will start automatically whenever OS/2 starts.
248 The directory you choose to install <application>Privoxy</application>
249 into will contain all of the configuration files.
253 <!-- ~~~~~ New section ~~~~~ -->
254 <sect3 id="installation-mac"><title>Mac OS X</title>
256 Installation instructions for the OS X platform depend upon whether
257 you downloaded a ready-built installation package (.pkg or .mpkg) or have
258 downloaded the source code.
261 <sect3 renderas="sect4" id="OS-X-install-from-package">
262 <title>Installation from ready-built package</title>
264 The downloaded file will either be a .pkg (for OS X 10.5 upwards) or a bzipped
265 .mpkg file (for OS X 10.4). The former can be double-clicked as is and the
266 installation will start; double-clicking the latter will unzip the .mpkg file
267 which can then be double-clicked to commence the installation.
270 The privoxy service will automatically start after a successful installation
271 (and thereafter every time your computer starts up) however you will need to
272 configure your web browser(s) to use it. To do so, configure them to use a
273 proxy for HTTP and HTTPS at the address 127.0.0.1:8118.
276 To prevent the privoxy service from automatically starting when your computer
277 starts up, remove or rename the file <literal>/Library/LaunchDaemons/org.ijbswa.privoxy.plist</literal>
278 (on OS X 10.5 and higher) or the folder named
279 <literal>/Library/StartupItems/Privoxy</literal> (on OS X 10.4 'Tiger').
282 To manually start or stop the privoxy service, use the scripts startPrivoxy.sh
283 and stopPrivoxy.sh supplied in /Applications/Privoxy. They must be run from an
284 administrator account, using sudo.
287 To uninstall, run /Applications/Privoxy/uninstall.command as sudo from an
288 administrator account.
291 <sect3 renderas="sect4" id="OS-X-install-from-source">
292 <title>Installation from source</title>
294 To build and install the Privoxy source code on OS X you will need to obtain
295 the macsetup module from the Privoxy Sourceforge CVS repository (refer to
296 Sourceforge help for details of how to set up a CVS client to have read-only
297 access to the repository). This module contains scripts that leverage the usual
298 open-source tools (available as part of Apple's free of charge Xcode
299 distribution or via the usual open-source software package managers for OS X
300 (MacPorts, Homebrew, Fink etc.) to build and then install the privoxy binary
301 and associated files. The macsetup module's README file contains complete
302 instructions for its use.
305 The privoxy service will automatically start after a successful installation
306 (and thereafter every time your computer starts up) however you will need to
307 configure your web browser(s) to use it. To do so, configure them to use a
308 proxy for HTTP and HTTPS at the address 127.0.0.1:8118.
311 To prevent the privoxy service from automatically starting when your computer
312 starts up, remove or rename the file <literal>/Library/LaunchDaemons/org.ijbswa.privoxy.plist</literal>
313 (on OS X 10.5 and higher) or the folder named
314 <literal>/Library/StartupItems/Privoxy</literal> (on OS X 10.4 'Tiger').
317 To manually start or stop the privoxy service, use the Privoxy Utility
318 for Mac OS X (also part of the macsetup module). This application can start
319 and stop the privoxy service and display its log and configuration files.
322 To uninstall, run the macsetup module's uninstall.sh as sudo from an
323 administrator account.
327 <!-- ~~~~~ New section ~~~~~ -->
328 <sect3 id="installation-freebsd"><title>FreeBSD</title>
331 Privoxy is part of FreeBSD's Ports Collection, you can build and install
332 it with <literal>cd /usr/ports/www/privoxy; make install clean</literal>.
338 <!-- ~~~~~ New section ~~~~~ -->
339 <sect2 id="installation-source"><title>Building from Source</title>
342 The most convenient way to obtain the <application>Privoxy</application> sources
343 is to download the source tarball from our
344 <ulink url="https://sourceforge.net/projects/ijbswa/files/Sources/">project download
349 If you like to live on the bleeding edge and are not afraid of using
350 possibly unstable development versions, you can check out the up-to-the-minute
351 version directly from <ulink url="https://sourceforge.net/p/ijbswa/code/?source=navbar">the
352 CVS repository</ulink>.
354 deprecated...out of business.
355 or simply download <ulink
356 url="http://cvs.sourceforge.net/cvstarballs/ijbswa-cvsroot.tar.bz2">the nightly CVS
361 <!-- include buildsource.sgml boilerplate: -->
363 <!-- end boilerplate -->
366 <!-- ~~~~~ New section ~~~~~ -->
367 <sect2 id="installation-keepupdated"><title>Keeping your Installation Up-to-Date</title>
370 If you wish to receive an email notification whenever we release updates of
371 <application>Privoxy</application> or the actions file, <ulink
372 url="https://lists.privoxy.org/mailman/listinfo/privoxy-announce">subscribe
373 to our announce mailing list</ulink>, privoxy-announce@lists.privoxy.org.
377 In order not to lose your personal changes and adjustments when updating
378 to the latest <literal>default.action</literal> file we <emphasis>strongly
379 recommend</emphasis> that you use <literal>user.action</literal> and
380 <literal>user.filter</literal> for your local
381 customizations of <application>Privoxy</application>. See the <link
382 linkend="actions-file">Chapter on actions files</link> for details.
390 <!-- ~ End section ~ -->
392 <!-- ~~~~~ New section ~~~~~ -->
393 <sect1 id="whatsnew">
394 <title>What's New in this Release</title>
398 <!-- ~~~~~ New section ~~~~~ -->
400 <sect2 id="upgradersnote">
401 <title>Note to Upgraders</title>
404 A quick list of things to be aware of before upgrading from earlier
405 versions of <application>Privoxy</application>:
412 The recommended way to upgrade &my-app; is to backup your old
413 configuration files, install the new ones, verify that &my-app;
414 is working correctly and finally merge back your changes using
415 <application>diff</application> and maybe <application>patch</application>.
418 There are a number of new features in each &my-app; release and
419 most of them have to be explicitly enabled in the configuration
420 files. Old configuration files obviously don't do that and due
421 to syntax changes using old configuration files with a new
422 &my-app; isn't always possible anyway.
427 Note that some installers remove earlier versions completely,
428 including configuration files, therefore you should really save
429 any important configuration files!
434 On the other hand, other installers don't overwrite existing configuration
435 files, thinking you will want to do that yourself.
440 In the default configuration only fatal errors are logged now.
441 You can change that in the <link linkend="DEBUG">debug section</link>
442 of the configuration file. You may also want to enable more verbose
443 logging until you verified that the new &my-app; version is working
450 Three other config file settings are now off by default:
451 <link linkend="enable-remote-toggle">enable-remote-toggle</link>,
452 <link linkend="enable-remote-http-toggle">enable-remote-http-toggle</link>,
453 and <link linkend="enable-edit-actions">enable-edit-actions</link>.
454 If you use or want these, you will need to explicitly enable them, and
455 be aware of the security issues involved.
462 What constitutes a <quote>default</quote> configuration has changed,
463 and you may want to review which actions are <quote>on</quote> by
464 default. This is primarily a matter of emphasis, but some features
465 you may have been used to, may now be <quote>off</quote> by default.
466 There are also a number of new actions and filters you may want to
467 consider, most of which are not fully incorporated into the default
468 settings as yet (see above).
475 The default actions setting is now <literal>Cautious</literal>. Previous
476 releases had a default setting of <literal>Medium</literal>. Experienced
477 users may want to adjust this, as it is fairly conservative by &my-app;
478 standards and past practices. See <ulink
479 url="http://config.privoxy.org/edit-actions-list?f=default">
480 http://config.privoxy.org/edit-actions-list?f=default</ulink>. New users
481 should try the default settings for a while before turning up the volume.
487 The default setting has filtering turned <emphasis>off</emphasis>, which
488 subsequently means that compression is <emphasis>on</emphasis>. Remember
489 that filtering does not work on compressed pages, so if you use, or want to
490 use, filtering, you will need to force compression off. Example:
493 { +<link linkend="filter">filter</link>{google} +<link linkend="prevent-compression">prevent-compression</link> }
496 Or if you use a number of filters, or filter many sites, you may just want
497 to turn off compression for all sites in
498 <filename>default.action</filename> (or
499 <filename>user.action</filename>).
506 Also, <link linkend="SESSION-COOKIES-ONLY">session-cookies-only</link> is
507 off by default now. If you've liked this feature in the past, you may want
508 to turn it back on in <filename>user.action</filename> now.
515 Some installers may not automatically start
516 <application>Privoxy</application> after installation.
526 <!-- ~~~~~ New section ~~~~~ -->
527 <sect1 id="quickstart"><title>Quickstart to Using Privoxy</title>
533 Install <application>Privoxy</application>. See the <link
534 linkend="installation">Installation Section</link> below for platform specific
541 Advanced users and those who want to offer <application>Privoxy</application>
542 service to more than just their local machine should check the <link
543 linkend="config">main config file</link>, especially the <link
544 linkend="access-control">security-relevant</link> options. These are
551 Start <application>Privoxy</application>, if the installation program has
552 not done this already (may vary according to platform). See the section
553 <link linkend="startup">Starting <application>Privoxy</application></link>.
559 Set your browser to use <application>Privoxy</application> as HTTP and
560 HTTPS (SSL) <ulink url="http://en.wikipedia.org/wiki/Proxy_server">proxy</ulink>
561 by setting the proxy configuration for address of
562 <literal>127.0.0.1</literal> and port <literal>8118</literal>.
563 <emphasis>DO NOT</emphasis> activate proxying for <literal>FTP</literal> or
564 any protocols besides HTTP and HTTPS (SSL) unless you intend to prevent your
565 browser from using these protocols.
571 Flush your browser's disk and memory caches, to remove any cached ad images.
572 If using <application>Privoxy</application> to manage
573 <ulink url="http://en.wikipedia.org/wiki/Browser_cookie">cookies</ulink>,
574 you should remove any currently stored cookies too.
580 A default installation should provide a reasonable starting point for
581 most. There will undoubtedly be occasions where you will want to adjust the
582 configuration, but that can be dealt with as the need arises. Little
583 to no initial configuration is required in most cases, you may want
585 <ulink url="config.html#ENABLE-EDIT-ACTIONS">web-based action editor</ulink> though.
586 Be sure to read the warnings first.
589 See the <link linkend="configuration">Configuration section</link> for more
590 configuration options, and how to customize your installation.
591 You might also want to look at the <link
592 linkend="quickstart-ad-blocking">next section</link> for a quick
593 introduction to how <application>Privoxy</application> blocks ads and
600 If you experience ads that slip through, innocent images that are
601 blocked, or otherwise feel the need to fine-tune
602 <application>Privoxy's</application> behavior, take a look at the <link
603 linkend="actions-file">actions files</link>. As a quick start, you might
604 find the <link linkend="act-examples">richly commented examples</link>
605 helpful. You can also view and edit the actions files through the <ulink
606 url="http://config.privoxy.org">web-based user interface</ulink>. The
607 Appendix <quote><link linkend="actionsanat">Troubleshooting: Anatomy of an
608 Action</link></quote> has hints on how to understand and debug actions that
609 <quote>misbehave</quote>.
615 Please see the section <link linkend="contact">Contacting the
616 Developers</link> on how to report bugs, problems with websites or to get
623 Now enjoy surfing with enhanced control, comfort and privacy!
630 <!-- ~~~~~ New section ~~~~~ -->
632 <sect2 id="quickstart-ad-blocking">
633 <title>Quickstart to Ad Blocking</title>
635 NOTE: This section is deliberately redundant for those that don't
636 want to read the whole thing (which is getting lengthy).
639 Ad blocking is but one of <application>Privoxy's</application>
640 array of features. Many of these features are for the technically minded advanced
641 user. But, ad and banner blocking is surely common ground for everybody.
644 This section will provide a quick summary of ad blocking so
645 you can get up to speed quickly without having to read the more extensive
646 information provided below, though this is highly recommended.
649 First a bit of a warning ... blocking ads is much like blocking SPAM: the
650 more aggressive you are about it, the more likely you are to block
651 things that were not intended. And the more likely that some things
652 may not work as intended. So there is a trade off here. If you want
653 extreme ad free browsing, be prepared to deal with more
654 <quote>problem</quote> sites, and to spend more time adjusting the
655 configuration to solve these unintended consequences. In short, there is
656 not an easy way to eliminate <emphasis>all</emphasis> ads. Either take
657 the easy way and settle for <emphasis>most</emphasis> ads blocked with the
658 default configuration, or jump in and tweak it for your personal surfing
659 habits and preferences.
662 Secondly, a brief explanation of <application>Privoxy's </application>
663 <quote>actions</quote>. <quote>Actions</quote> in this context, are
664 the directives we use to tell <application>Privoxy</application> to perform
665 some task relating to HTTP transactions (i.e. web browsing). We tell
666 <application>Privoxy</application> to take some <quote>action</quote>. Each
667 action has a unique name and function. While there are many potential
668 <application>actions</application> in <application>Privoxy's</application>
669 arsenal, only a few are used for ad blocking. <link
670 linkend="actions">Actions</link>, and <link linkend="actions-file">action
671 configuration files</link>, are explained in depth below.
674 Actions are specified in <application>Privoxy's</application> configuration,
675 followed by one or more URLs to which the action should apply. URLs
676 can actually be URL type <link linkend="af-patterns">patterns</link> that use
677 wildcards so they can apply potentially to a range of similar URLs. The
678 actions, together with the URL patterns are called a section.
681 When you connect to a website, the full URL will either match one or more
682 of the sections as defined in <application>Privoxy's</application> configuration,
683 or not. If so, then <application>Privoxy</application> will perform the
684 respective actions. If not, then nothing special happens. Furthermore, web
685 pages may contain embedded, secondary URLs that your web browser will
686 use to load additional components of the page, as it parses the
687 original page's HTML content. An ad image for instance, is just an URL
688 embedded in the page somewhere. The image itself may be on the same server,
689 or a server somewhere else on the Internet. Complex web pages will have many
690 such embedded URLs. &my-app; can deal with each URL individually, so, for
691 instance, the main page text is not touched, but images from such-and-such
696 The most important actions for basic ad blocking are: <literal><link
697 linkend="block">block</link></literal>, <literal><link
698 linkend="handle-as-image">handle-as-image</link></literal>,
700 linkend="handle-as-empty-document">handle-as-empty-document</link></literal>,and
701 <literal><link linkend="set-image-blocker">set-image-blocker</link></literal>:
708 <literal><link linkend="block">block</link></literal> - this is perhaps
709 the single most used action, and is particularly important for ad blocking.
710 This action stops any contact between your browser and any URL patterns
711 that match this action's configuration. It can be used for blocking ads,
712 but also anything that is determined to be unwanted. By itself, it simply
713 stops any communication with the remote server and sends
714 <application>Privoxy</application>'s own built-in BLOCKED page instead to
715 let you now what has happened (with some exceptions, see below).
721 <literal><link linkend="handle-as-image">handle-as-image</link></literal> -
722 tells <application>Privoxy</application> to treat this URL as an image.
723 <application>Privoxy</application>'s default configuration already does this
724 for all common image types (e.g. GIF), but there are many situations where this
725 is not so easy to determine. So we'll force it in these cases. This is particularly
726 important for ad blocking, since only if we know that it's an image of
727 some kind, can we replace it with an image of our choosing, instead of the
728 <application>Privoxy</application> BLOCKED page (which would only result in
729 a <quote>broken image</quote> icon). There are some limitations to this
730 though. For instance, you can't just brute-force an image substitution for
731 an entire HTML page in most situations.
737 <literal><link linkend="handle-as-empty-document">handle-as-empty-document</link></literal> -
738 sends an empty document instead of <application>Privoxy's</application>
739 normal BLOCKED HTML page. This is useful for file types that are neither
740 HTML nor images, such as blocking JavaScript files.
747 linkend="set-image-blocker">set-image-blocker</link></literal> - tells
748 <application>Privoxy</application> what to display in place of an ad image that
749 has hit a block rule. For this to come into play, the URL must match a
750 <literal><link linkend="block">block</link></literal> action somewhere in the
751 configuration, <emphasis>and</emphasis>, it must also match an
752 <literal><link linkend="handle-as-image">handle-as-image</link></literal> action.
755 The configuration options on what to display instead of the ad are:
759 <emphasis>pattern</emphasis> - a checkerboard pattern, so that an ad
760 replacement is obvious. This is the default.
765 <emphasis>blank</emphasis> - A very small empty GIF image is displayed.
766 This is the so-called <quote>invisible</quote> configuration option.
771 <emphasis>http://<URL></emphasis> - A redirect to any image anywhere
772 of the user's choosing (advanced usage).
780 Advanced users will eventually want to explore &my-app;
781 <literal><link linkend="filter">filters</link></literal> as well. Filters
782 are very different from <literal><link
783 linkend="block">blocks</link></literal>.
784 A <quote>block</quote> blocks a site, page, or unwanted contented. Filters
785 are a way of filtering or modifying what is actually on the page. An example
786 filter usage: a text replacement of <quote>no-no</quote> for
787 <quote>nasty-word</quote>. That is a very simple example. This process can be
788 used for ad blocking, but it is more in the realm of advanced usage and has
789 some pitfalls to be wary off.
793 The quickest way to adjust any of these settings is with your browser through
794 the special <application>Privoxy</application> editor at <ulink
795 url="http://config.privoxy.org/show-status">http://config.privoxy.org/show-status</ulink>
796 (shortcut: <ulink url="http://p.p/">http://p.p/show-status</ulink>). This
797 is an internal page, and does not require Internet access.
801 Note that as of <application>Privoxy</application> 3.0.7 beta the
802 action editor is disabled by default. Check the
803 <ulink url="config.html#ENABLE-EDIT-ACTIONS">enable-edit-actions
804 section in the configuration file</ulink> to learn why and in which
805 cases it's safe to enable again.
809 If you decided to enable the action editor, select the appropriate
810 <quote>actions</quote> file, and click
811 <quote><guibutton>Edit</guibutton></quote>. It is best to put personal or
812 local preferences in <filename>user.action</filename> since this is not
813 meant to be overwritten during upgrades, and will over-ride the settings in
814 other files. Here you can insert new <quote>actions</quote>, and URLs for ad
815 blocking or other purposes, and make other adjustments to the configuration.
816 <application>Privoxy</application> will detect these changes automatically.
820 A quick and simple step by step example:
827 Right click on the ad image to be blocked, then select
828 <quote><guimenuitem>Copy Link Location</guimenuitem></quote> from the
836 url="http://config.privoxy.org/show-status">http://config.privoxy.org/show-status</ulink>
841 Find <filename>user.action</filename> in the top section, and click
842 on <quote><guibutton>Edit</guibutton></quote>:
845 <!-- image of editor and actions files selections -->
846 <figure pgwide="0" float="0"><title>Actions Files in Use</title>
849 <imagedata fileref="files-in-use.jpg" format="jpg">
852 <phrase>[ Screenshot of Actions Files in Use ]</phrase>
860 You should have a section with only
861 <literal><link linkend="block">block</link></literal> listed under
862 <quote>Actions:</quote>.
863 If not, click a <quote><guibutton>Insert new section below</guibutton></quote>
864 button, and in the new section that just appeared, click the
865 <guibutton>Edit</guibutton> button right under the word <quote>Actions:</quote>.
866 This will bring up a list of all actions. Find
867 <literal><link linkend="block">block</link></literal> near the top, and click
868 in the <quote>Enabled</quote> column, then <quote><guibutton>Submit</guibutton></quote>
874 Now, in the <literal><link linkend="block">block</link></literal> actions section,
875 click the <quote><guibutton>Add</guibutton></quote> button, and paste the URL the
876 browser got from <quote><guimenuitem>Copy Link Location</guimenuitem></quote>.
877 Remove the <literal>http://</literal> at the beginning of the URL. Then, click
878 <quote><guibutton>Submit</guibutton></quote> (or
879 <quote><guibutton>OK</guibutton></quote> if in a pop-up window).
884 Now go back to the original page, and press <keycap>SHIFT-Reload</keycap>
885 (or flush all browser caches). The image should be gone now.
892 This is a very crude and simple example. There might be good reasons to use a
893 wildcard pattern match to include potentially similar images from the same
894 site. For a more extensive explanation of <quote>patterns</quote>, and
895 the entire actions concept, see <link linkend="actions-file">the Actions
900 For advanced users who want to hand edit their config files, you might want
901 to now go to the <link linkend="act-examples">Actions Files Tutorial</link>.
902 The ideas explained therein also apply to the web-based editor.
905 There are also various
906 <link linkend="filter">filters</link> that can be used for ad blocking
907 (filters are a special subset of actions). These
908 fall into the <quote>advanced</quote> usage category, and are explained in
909 depth in later sections.
916 <!-- ~ End section ~ -->
919 <!-- ~~~~~ New section ~~~~~ -->
921 <title>Starting Privoxy</title>
923 Before launching <application>Privoxy</application> for the first time, you
924 will want to configure your browser(s) to use
925 <application>Privoxy</application> as a HTTP and HTTPS (SSL)
926 <ulink url="http://en.wikipedia.org/wiki/Proxy_server">proxy</ulink>. The default is
927 127.0.0.1 (or localhost) for the proxy address, and port 8118 (earlier versions
928 used port 8000). This is the one configuration step <emphasis>that must be done
932 Please note that <application>Privoxy</application> can only proxy HTTP and
933 HTTPS traffic. It will not work with FTP or other protocols.
936 <!-- image of Mozilla Proxy configuration -->
937 <figure pgwide="0" float="0"><title>Proxy Configuration Showing
938 Mozilla/Netscape HTTP and HTTPS (SSL) Settings</title>
941 <imagedata fileref="proxy_setup.jpg" format="jpg">
944 <phrase>[ Screenshot of Mozilla Proxy Configuration ]</phrase>
951 With <application>Firefox</application>, this is typically set under:
955 <guibutton>Tools</guibutton> -> <guibutton>Options</guibutton> -> <guibutton>Advanced</guibutton> -> <guibutton>Network</guibutton> -><guibutton>Connection</guibutton> -> <guibutton>Settings</guibutton>
959 Or optionally on some platforms:
963 <guibutton>Edit</guibutton> -> <guibutton>Preferences</guibutton> -> <guibutton>General</guibutton> -> <guibutton>Connection Settings</guibutton> -> <guibutton>Manual Proxy Configuration</guibutton>
968 With <application>Netscape</application> (and
969 <application>Mozilla</application>), this can be set under:
974 <!-- Mix ascii and gui art, something for everybody -->
975 <!-- spacing on this is tricky -->
976 <guibutton>Edit</guibutton> -> <guibutton>Preferences</guibutton> -> <guibutton>Advanced</guibutton> -> <guibutton>Proxies</guibutton> -> <guibutton>HTTP Proxy</guibutton>
980 For <application>Internet Explorer v.5-7</application>:
984 <guibutton>Tools</guibutton> -> <guibutton>Internet Options</guibutton> -> <guibutton>Connections</guibutton> -> <guibutton>LAN Settings</guibutton>
988 Then, check <quote>Use Proxy</quote> and fill in the appropriate info
989 (Address: 127.0.0.1, Port: 8118). Include HTTPS (SSL), if you want HTTPS
990 proxy support too (sometimes labeled <quote>Secure</quote>). Make sure any
991 checkboxes like <quote>Use the same proxy server for all protocols</quote> is
992 <emphasis>UNCHECKED</emphasis>. You want only HTTP and HTTPS (SSL)!
995 <!-- image of IE Proxy configuration -->
996 <figure pgwide="0" float="0"><title>Proxy Configuration Showing
997 Internet Explorer HTTP and HTTPS (Secure) Settings</title>
1000 <imagedata fileref="proxy2.jpg" format="jpg">
1003 <phrase>[ Screenshot of IE Proxy Configuration ]</phrase>
1010 After doing this, flush your browser's disk and memory caches to force a
1011 re-reading of all pages and to get rid of any ads that may be cached. Remove
1012 any <ulink url="http://en.wikipedia.org/wiki/Browser_cookie">cookies</ulink>,
1013 if you want <application>Privoxy</application> to manage that. You are now
1014 ready to start enjoying the benefits of using
1015 <application>Privoxy</application>!
1019 <application>Privoxy</application> itself is typically started by specifying the
1020 main configuration file to be used on the command line. If no configuration
1021 file is specified on the command line, <application>Privoxy</application>
1022 will look for a file named <filename>config</filename> in the current
1023 directory. Except on Win32 where it will try <filename>config.txt</filename>.
1026 <sect2 id="start-debian">
1027 <title>Debian</title>
1029 We use a script. Note that Debian typically starts &my-app; upon booting per
1030 default. It will use the file
1031 <filename>/etc/privoxy/config</filename> as its main configuration
1035 # /etc/init.d/privoxy start
1039 <sect2 id="start-freebsd">
1040 <title>FreeBSD and ElectroBSD</title>
1042 To start <application>Privoxy</application> upon booting, add
1043 "privoxy_enable='YES'" to <filename>/etc/rc.conf</filename>.
1044 <application>Privoxy</application> will use
1045 <filename>/usr/local/etc/privoxy/config</filename> as its main
1049 If you installed <application>Privoxy</application> into a jail, the
1050 paths above are relative to the jail root.
1053 To start <application>Privoxy</application> manually, run:
1056 # service privoxy onestart
1060 <sect2 id="start-windows">
1061 <title>Windows</title>
1063 Click on the &my-app; Icon to start <application>Privoxy</application>. If no configuration file is
1064 specified on the command line, <application>Privoxy</application> will look
1065 for a file named <filename>config.txt</filename>. Note that Windows will
1066 automatically start &my-app; when the system starts if you chose that option
1070 <application>Privoxy</application> can run with full Windows service functionality.
1071 On Windows only, the &my-app; program has two new command line arguments
1072 to install and uninstall &my-app; as a service. See the
1073 <link linkend="installation-pack-win">Windows Installation
1074 instructions</link> for details.
1078 <sect2 id="start-unices">
1079 <title>Generic instructions for Unix derivates (Solaris, NetBSD, HP-UX etc.)</title>
1081 Example Unix startup command:
1084 # /usr/sbin/privoxy --user privoxy /etc/privoxy/config
1087 Note that if you installed <application>Privoxy</application> through
1088 a package manager, the package will probably contain a platform-specific
1089 script or configuration file to start <application>Privoxy</application>
1094 <sect2 id="start-os2">
1097 During installation, <application>Privoxy</application> is configured to
1098 start automatically when the system restarts. You can start it manually by
1099 double-clicking on the <application>Privoxy</application> icon in the
1100 <application>Privoxy</application> folder.
1104 <sect2 id="start-macosx">
1105 <title>Mac OS X</title>
1107 The privoxy service will automatically start after a successful installation
1108 (and thereafter every time your computer starts up) however you will need to
1109 configure your web browser(s) to use it. To do so, configure them to use a
1110 proxy for HTTP and HTTPS at the address 127.0.0.1:8118.
1113 To prevent the privoxy service from automatically starting when your computer
1114 starts up, remove or rename the file <literal>/Library/LaunchDaemons/org.ijbswa.privoxy.plist</literal>
1115 (on OS X 10.5 and higher) or the folder named
1116 <literal>/Library/StartupItems/Privoxy</literal> (on OS X 10.4 'Tiger').
1119 To manually start or stop the privoxy service, use the scripts startPrivoxy.sh
1120 and stopPrivoxy.sh supplied in /Applications/Privoxy. They must be run from an
1121 administrator account, using sudo.
1129 See the section <link linkend="cmdoptions">Command line options</link> for
1133 must find a better place for this paragraph
1136 The included default configuration files should give a reasonable starting
1137 point. Most of the per site configuration is done in the
1138 <ulink url="actions-file.html"><quote>actions</quote></ulink> files. These are
1139 where various cookie actions are defined, ad and banner blocking, and other
1140 aspects of <application>Privoxy</application> configuration. There are several
1141 such files included, with varying levels of aggressiveness.
1145 You will probably want to keep an eye out for sites for which you may prefer
1146 persistent cookies, and add these to your actions configuration as needed. By
1147 default, most of these will be accepted only during the current browser
1148 session (aka <quote>session cookies</quote>), unless you add them to the
1149 configuration. If you want the browser to handle this instead, you will need
1150 to edit <filename>user.action</filename> (or through the web based interface)
1151 and disable this feature. If you use more than one browser, it would make
1152 more sense to let <application>Privoxy</application> handle this. In which
1153 case, the browser(s) should be set to accept all cookies.
1157 Another feature where you will probably want to define exceptions for trusted
1158 sites is the popup-killing (through <ulink
1159 url="actions-file.html#FILTER-POPUPS"><quote>+filter{popups}</quote></ulink>),
1160 because your favorite shopping, banking, or leisure site may need
1161 popups (explained below).
1165 <application>Privoxy</application> does not support all of the optional HTTP/1.1
1166 features yet. In the unlikely event that you experience inexplicable problems
1167 with browsers that use HTTP/1.1 per default
1168 (like <application>Mozilla</application> or recent versions of I.E.), you might
1169 try to force HTTP/1.0 compatibility. For Mozilla, look under <literal>Edit ->
1170 Preferences -> Debug -> Networking</literal>.
1171 Alternatively, set the <quote>+downgrade-http-version</quote> config option in
1172 <filename>default.action</filename> which will downgrade your browser's HTTP
1173 requests from HTTP/1.1 to HTTP/1.0 before processing them.
1177 After running <application>Privoxy</application> for a while, you can
1178 start to fine tune the configuration to suit your personal, or site,
1179 preferences and requirements. There are many, many aspects that can
1180 be customized. <quote>Actions</quote>
1181 can be adjusted by pointing your browser to
1182 <ulink url="http://config.privoxy.org/">http://config.privoxy.org/</ulink>
1183 (shortcut: <ulink url="http://p.p/">http://p.p/</ulink>),
1184 and then follow the link to <quote>View & Change the Current Configuration</quote>.
1185 (This is an internal page and does not require Internet access.)
1189 In fact, various aspects of <application>Privoxy</application>
1190 configuration can be viewed from this page, including
1191 current configuration parameters, source code version numbers,
1192 the browser's request headers, and <quote>actions</quote> that apply
1193 to a given URL. In addition to the actions file
1194 editor mentioned above, <application>Privoxy</application> can also
1195 be turned <quote>on</quote> and <quote>off</quote> (toggled) from this page.
1199 If you encounter problems, try loading the page without
1200 <application>Privoxy</application>. If that helps, enter the URL where
1201 you have the problems into <ulink url="http://p.p/show-url-info">the browser
1202 based rule tracing utility</ulink>. See which rules apply and why, and
1203 then try turning them off for that site one after the other, until the problem
1204 is gone. When you have found the culprit, you might want to turn the rest on
1209 If the above paragraph sounds gibberish to you, you might want to <link
1210 linkend="actions-file">read more about the actions concept</link>
1211 or even dive deep into the <link linkend="actionsanat">Appendix
1216 If you can't get rid of the problem at all, think you've found a bug in
1217 Privoxy, want to propose a new feature or smarter rules, please see the
1218 section <link linkend="contact"><quote>Contacting the
1219 Developers</quote></link> below.
1224 <!-- ~~~~~ New section ~~~~~ -->
1225 <sect2 id="cmdoptions">
1226 <title>Command Line Options</title>
1228 <application>Privoxy</application> may be invoked with the following
1229 command-line options:
1236 <emphasis>--config-test</emphasis>
1239 Exit after loading the configuration files before binding to
1240 the listen address. The exit code signals whether or not the
1241 configuration files have been successfully loaded.
1244 If the exit code is 1, at least one of the configuration files
1245 is invalid, if it is 0, all the configuration files have been
1246 successfully loaded (but may still contain errors that can
1247 currently only be detected at run time).
1250 This option doesn't affect the log setting, combination with
1251 <emphasis>--no-daemon</emphasis> is recommended if a configured
1252 log file shouldn't be used.
1257 <emphasis>--version</emphasis>
1260 Print version info and exit. Unix only.
1265 <emphasis>--help</emphasis>
1268 Print short usage info and exit. Unix only.
1273 <emphasis>--no-daemon</emphasis>
1276 Don't become a daemon, i.e. don't fork and become process group
1277 leader, and don't detach from controlling tty. Unix only.
1282 <emphasis>--pidfile FILE</emphasis>
1285 On startup, write the process ID to <emphasis>FILE</emphasis>. Delete the
1286 <emphasis>FILE</emphasis> on exit. Failure to create or delete the
1287 <emphasis>FILE</emphasis> is non-fatal. If no <emphasis>FILE</emphasis>
1288 option is given, no PID file will be used. Unix only.
1293 <emphasis>--user USER[.GROUP]</emphasis>
1296 After (optionally) writing the PID file, assume the user ID of
1297 <emphasis>USER</emphasis>, and if included the GID of GROUP. Exit if the
1298 privileges are not sufficient to do so. Unix only.
1303 <emphasis>--chroot</emphasis>
1306 Before changing to the user ID given in the <emphasis>--user</emphasis> option,
1307 chroot to that user's home directory, i.e. make the kernel pretend to the &my-app;
1308 process that the directory tree starts there. If set up carefully, this can limit
1309 the impact of possible vulnerabilities in &my-app; to the files contained in that hierarchy.
1315 <emphasis>--pre-chroot-nslookup hostname</emphasis>
1318 Specifies a hostname (for example www.privoxy.org) to look up before doing a chroot.
1319 On some systems, initializing the resolver library involves reading config files from
1320 /etc and/or loading additional shared libraries from /lib.
1321 On these systems, doing a hostname lookup before the chroot reduces
1322 the number of files that must be copied into the chroot tree.
1325 For fastest startup speed, a good value is a hostname that is not in /etc/hosts but that
1326 your local name server (listed in /etc/resolv.conf) can resolve without recursion
1327 (that is, without having to ask any other name servers). The hostname need not exist,
1328 but if it doesn't, an error message (which can be ignored) will be output.
1334 <emphasis>configfile</emphasis>
1337 If no <emphasis>configfile</emphasis> is included on the command line,
1338 <application>Privoxy</application> will look for a file named
1339 <quote>config</quote> in the current directory (except on Win32
1340 where it will look for <quote>config.txt</quote> instead). Specify
1341 full path to avoid confusion. If no config file is found,
1342 <application>Privoxy</application> will fail to start.
1349 On <application>MS Windows</application> only there are two additional
1350 command-line options to allow <application>Privoxy</application> to install and
1351 run as a <emphasis>service</emphasis>. See the
1352 <link linkend="installation-pack-win">Window Installation section</link>
1360 <!-- ~ End section ~ -->
1363 <!-- ~~~~~ New section ~~~~~ -->
1364 <sect1 id="configuration"><title>Privoxy Configuration</title>
1366 All <application>Privoxy</application> configuration is stored
1367 in text files. These files can be edited with a text editor.
1368 Many important aspects of <application>Privoxy</application> can
1369 also be controlled easily with a web browser.
1373 <!-- ~~~~~ New section ~~~~~ -->
1375 <sect2 id="control-with-webbrowser">
1376 <title>Controlling Privoxy with Your Web Browser</title>
1378 <application>Privoxy</application>'s user interface can be reached through the special
1379 URL <ulink url="http://config.privoxy.org/">http://config.privoxy.org/</ulink>
1380 (shortcut: <ulink url="http://p.p/">http://p.p/</ulink>),
1381 which is a built-in page and works without Internet access.
1382 You will see the following section:
1385 <!-- Needs to be put in a table and colorized -->
1388 <bridgehead renderas="sect2"> Privoxy Menu</bridgehead>
1392 ▪ <ulink url="http://config.privoxy.org/show-status">View & change the current configuration</ulink>
1395 ▪ <ulink url="http://config.privoxy.org/show-version">View the source code version numbers</ulink>
1398 ▪ <ulink url="http://config.privoxy.org/show-request">View the request headers.</ulink>
1401 ▪ <ulink url="http://config.privoxy.org/show-url-info">Look up which actions apply to a URL and why</ulink>
1404 ▪ <ulink url="http://config.privoxy.org/toggle">Toggle Privoxy on or off</ulink>
1407 ▪ <ulink
1408 url="https://www.privoxy.org/&p-version;/user-manual/">Documentation</ulink>
1416 This should be self-explanatory. Note the first item leads to an editor for the
1417 <link linkend="actions-file">actions files</link>, which is where the ad, banner,
1418 cookie, and URL blocking magic is configured as well as other advanced features of
1419 <application>Privoxy</application>. This is an easy way to adjust various
1420 aspects of <application>Privoxy</application> configuration. The actions
1421 file, and other configuration files, are explained in detail below.
1425 <quote>Toggle Privoxy On or Off</quote> is handy for sites that might
1426 have problems with your current actions and filters. You can in fact use
1427 it as a test to see whether it is <application>Privoxy</application>
1428 causing the problem or not. <application>Privoxy</application> continues
1429 to run as a proxy in this case, but all manipulation is disabled, i.e.
1430 <application>Privoxy</application> acts like a normal forwarding proxy.
1434 Note that several of the features described above are disabled by default
1435 in <application>Privoxy</application> 3.0.7 beta and later.
1437 <ulink url="config.html">configuration file</ulink> to learn why
1438 and in which cases it's safe to enable them again.
1443 <!-- ~ End section ~ -->
1448 <!-- ~~~~~ New section ~~~~~ -->
1450 <sect2 id="confoverview">
1451 <title>Configuration Files Overview</title>
1453 For Unix, *BSD and Linux, all configuration files are located in
1454 <filename>/etc/privoxy/</filename> by default. For MS Windows, OS/2, and
1455 AmigaOS these are all in the same directory as the
1456 <application>Privoxy</application> executable. <![%p-not-stable;[ The name
1457 and number of configuration files has changed from previous versions, and is
1458 subject to change as development progresses.]]>
1462 The installed defaults provide a reasonable starting point, though
1463 some settings may be aggressive by some standards. For the time being, the
1464 principle configuration files are:
1471 The <link linkend="config">main configuration file</link> is named <filename>config</filename>
1472 on Linux, Unix, BSD, OS/2, and AmigaOS and <filename>config.txt</filename>
1473 on Windows. This is a required file.
1479 <filename>match-all.action</filename> is used to define which <quote>actions</quote>
1480 relating to banner-blocking, images, pop-ups, content modification, cookie handling
1481 etc should be applied by default. It should be the first actions file loaded.
1484 <filename>default.action</filename> defines many exceptions (both positive and negative)
1485 from the default set of actions that's configured in <filename>match-all.action</filename>.
1486 It should be the second actions file loaded and shouldn't be edited by the user.
1489 Multiple actions files may be defined in <filename>config</filename>. These
1490 are processed in the order they are defined. Local customizations and locally
1491 preferred exceptions to the default policies as defined in
1492 <filename>match-all.action</filename> (which you will most probably want
1493 to define sooner or later) are best applied in <filename>user.action</filename>,
1494 where you can preserve them across upgrades. The file isn't installed by all
1495 installers, but you can easily create it yourself with a text editor.
1498 There is also a web based editor that can be accessed from
1500 url="http://config.privoxy.org/show-status">http://config.privoxy.org/show-status</ulink>
1502 url="http://p.p/show-status">http://p.p/show-status</ulink>) for the
1503 various actions files.
1509 <quote>Filter files</quote> (the <link linkend="filter-file">filter
1510 file</link>) can be used to re-write the raw page content, including
1511 viewable text as well as embedded HTML and JavaScript, and whatever else
1512 lurks on any given web page. The filtering jobs are only pre-defined here;
1513 whether to apply them or not is up to the actions files.
1514 <filename>default.filter</filename> includes various filters made
1515 available for use by the developers. Some are much more intrusive than
1516 others, and all should be used with caution. You may define additional
1517 filter files in <filename>config</filename> as you can with
1518 actions files. We suggest <filename>user.filter</filename> for any
1519 locally defined filters or customizations.
1526 The syntax of the configuration and filter files may change between different
1527 Privoxy versions, unfortunately some enhancements cost backwards compatibility.
1528 <!-- Add link to documentation-->
1532 All files use the <quote><literal>#</literal></quote> character to denote a
1533 comment (the rest of the line will be ignored) and understand line continuation
1534 through placing a backslash ("<literal>\</literal>") as the very last character
1535 in a line. If the <literal>#</literal> is preceded by a backslash, it looses
1536 its special function. Placing a <literal>#</literal> in front of an otherwise
1537 valid configuration line to prevent it from being interpreted is called "commenting
1538 out" that line. Blank lines are ignored.
1542 The actions files and filter files
1543 can use Perl style <link linkend="regex">regular expressions</link> for
1544 maximum flexibility.
1548 After making any changes, there is no need to restart
1549 <application>Privoxy</application> in order for the changes to take
1550 effect. <application>Privoxy</application> detects such changes
1551 automatically. Note, however, that it may take one or two additional
1552 requests for the change to take effect. When changing the listening address
1553 of <application>Privoxy</application>, these <quote>wake up</quote> requests
1554 must obviously be sent to the <emphasis>old</emphasis> listening address.
1559 While under development, the configuration content is subject to change.
1560 The below documentation may not be accurate by the time you read this.
1561 Also, what constitutes a <quote>default</quote> setting, may change, so
1562 please check all your configuration files on important issues.
1568 <!-- ~ End section ~ -->
1571 <!-- ~~~~~~~~ New section Header ~~~~~~~~~ -->
1573 <!-- **************************************************** -->
1574 <!-- Include config.sgml here -->
1575 <!-- This is where the entire config file is detailed. -->
1577 <!-- end include -->
1580 <!-- ~ End section ~ -->
1584 <!-- ~~~~~~~~ New section Header ~~~~~~~~~ -->
1586 <sect1 id="actions-file"><title>Actions Files</title>
1590 XXX: similar descriptions are in the Configuration Files sections.
1591 We should only describe them at one place.
1594 The actions files are used to define what <emphasis>actions</emphasis>
1595 <application>Privoxy</application> takes for which URLs, and thus determines
1596 how ad images, cookies and various other aspects of HTTP content and
1597 transactions are handled, and on which sites (or even parts thereof).
1598 There are a number of such actions, with a wide range of functionality.
1599 Each action does something a little different.
1600 These actions give us a veritable arsenal of tools with which to exert
1601 our control, preferences and independence. Actions can be combined so that
1602 their effects are aggregated when applied against a given set of URLs.
1606 are three action files included with <application>Privoxy</application> with
1612 <filename>match-all.action</filename> - is used to define which
1613 <quote>actions</quote> relating to banner-blocking, images, pop-ups,
1614 content modification, cookie handling etc should be applied by default.
1615 It should be the first actions file loaded
1620 <filename>default.action</filename> - defines many exceptions (both
1621 positive and negative) from the default set of actions that's configured
1622 in <filename>match-all.action</filename>. It is a set of rules that should
1623 work reasonably well as-is for most users. This file is only supposed to
1624 be edited by the developers. It should be the second actions file loaded.
1629 <filename>user.action</filename> - is intended to be for local site
1630 preferences and exceptions. As an example, if your ISP or your bank
1631 has specific requirements, and need special handling, this kind of
1632 thing should go here. This file will not be upgraded.
1637 <guibutton>Edit</guibutton> <guibutton>Set to Cautious</guibutton> <guibutton>Set to Medium</guibutton> <guibutton>Set to Advanced</guibutton>
1640 These have increasing levels of aggressiveness <emphasis>and have no
1641 influence on your browsing unless you select them explicitly in the
1642 editor</emphasis>. A default installation should be pre-set to
1643 <literal>Cautious</literal>. New users should try this for a while before
1644 adjusting the settings to more aggressive levels. The more aggressive
1645 the settings, then the more likelihood there is of problems such as sites
1646 not working as they should.
1649 The <guibutton>Edit</guibutton> button allows you to turn each
1650 action on/off individually for fine-tuning. The <guibutton>Cautious</guibutton>
1651 button changes the actions list to low/safe settings which will activate
1652 ad blocking and a minimal set of &my-app;'s features, and subsequently
1653 there will be less of a chance for accidental problems. The
1654 <guibutton>Medium</guibutton> button sets the list to a medium level of
1655 other features and a low level set of privacy features. The
1656 <guibutton>Advanced</guibutton> button sets the list to a high level of
1657 ad blocking and medium level of privacy. See the chart below. The latter
1658 three buttons over-ride any changes via with the
1659 <guibutton>Edit</guibutton> button. More fine-tuning can be done in the
1660 lower sections of this internal page.
1663 While the actions file editor allows to enable these settings in all
1664 actions files, they are only supposed to be enabled in the first one
1665 to make sure you don't unintentionally overrule earlier rules.
1668 The default profiles, and their associated actions, as pre-defined in
1669 <filename>default.action</filename> are:
1671 <table frame=all><title>Default Configurations</title>
1672 <tgroup cols=4 align=left colsep=1 rowsep=1>
1673 <colspec colname=c1>
1674 <colspec colname=c2>
1675 <colspec colname=c3>
1676 <colspec colname=c4>
1679 <entry>Feature</entry>
1680 <entry>Cautious</entry>
1681 <entry>Medium</entry>
1682 <entry>Advanced</entry>
1687 <!-- <entry>f1</entry> -->
1688 <!-- <entry>f2</entry> -->
1689 <!-- <entry>f3</entry> -->
1690 <!-- <entry>f4</entry> -->
1696 <entry>Ad-blocking Aggressiveness</entry>
1697 <entry>medium</entry>
1703 <entry>Ad-filtering by size</entry>
1710 <entry>Ad-filtering by link</entry>
1716 <entry>Pop-up killing</entry>
1717 <entry>blocks only</entry>
1718 <entry>blocks only</entry>
1719 <entry>blocks only</entry>
1723 <entry>Privacy Features</entry>
1725 <entry>medium</entry>
1726 <entry>medium/high</entry>
1730 <entry>Cookie handling</entry>
1732 <entry>session-only</entry>
1737 <entry>Referer forging</entry>
1744 <entry>GIF de-animation</entry>
1751 <entry>Fast redirects</entry>
1758 <entry>HTML taming</entry>
1765 <entry>JavaScript taming</entry>
1772 <entry>Web-bug killing</entry>
1779 <entry>Image tag reordering</entry>
1793 The list of actions files to be used are defined in the main configuration
1794 file, and are processed in the order they are defined (e.g.
1795 <filename>default.action</filename> is typically processed before
1796 <filename>user.action</filename>). The content of these can all be viewed and
1798 url="http://config.privoxy.org/show-status">http://config.privoxy.org/show-status</ulink>.
1799 The over-riding principle when applying actions, is that the last action that
1800 matches a given URL wins. The broadest, most general rules go first
1801 (defined in <filename>default.action</filename>),
1802 followed by any exceptions (typically also in
1803 <filename>default.action</filename>), which are then followed lastly by any
1804 local preferences (typically in <emphasis>user</emphasis><filename>.action</filename>).
1805 Generally, <filename>user.action</filename> has the last word.
1809 An actions file typically has multiple sections. If you want to use
1810 <quote>aliases</quote> in an actions file, you have to place the (optional)
1811 <link linkend="aliases">alias section</link> at the top of that file.
1812 Then comes the default set of rules which will apply universally to all
1813 sites and pages (be <emphasis>very careful</emphasis> with using such a
1814 universal set in <filename>user.action</filename> or any other actions file after
1815 <filename>default.action</filename>, because it will override the result
1816 from consulting any previous file). And then below that,
1817 exceptions to the defined universal policies. You can regard
1818 <filename>user.action</filename> as an appendix to <filename>default.action</filename>,
1819 with the advantage that it is a separate file, which makes preserving your
1820 personal settings across <application>Privoxy</application> upgrades easier.
1824 Actions can be used to block anything you want, including ads, banners, or
1825 just some obnoxious URL whose content you would rather not see. Cookies can be accepted
1826 or rejected, or accepted only during the current browser session (i.e. not
1827 written to disk), content can be modified, some JavaScripts tamed, user-tracking
1828 fooled, and much more. See below for a <link linkend="actions">complete list
1832 <!-- ~~~~~ New section ~~~~~ -->
1833 <sect2 id="right-mix">
1834 <title>Finding the Right Mix</title>
1836 Note that some <link linkend="actions">actions</link>, like cookie suppression
1837 or script disabling, may render some sites unusable that rely on these
1838 techniques to work properly. Finding the right mix of actions is not always easy and
1839 certainly a matter of personal taste. And, things can always change, requiring
1840 refinements in the configuration. In general, it can be said that the more
1841 <quote>aggressive</quote> your default settings (in the top section of the
1842 actions file) are, the more exceptions for <quote>trusted</quote> sites you
1843 will have to make later. If, for example, you want to crunch all cookies per
1844 default, you'll have to make exceptions from that rule for sites that you
1845 regularly use and that require cookies for actually useful purposes, like maybe
1846 your bank, favorite shop, or newspaper.
1850 We have tried to provide you with reasonable rules to start from in the
1851 distribution actions files. But there is no general rule of thumb on these
1852 things. There just are too many variables, and sites are constantly changing.
1853 Sooner or later you will want to change the rules (and read this chapter again :).
1857 <!-- ~~~~~ New section ~~~~~ -->
1858 <sect2 id="how-to-edit">
1859 <title>How to Edit</title>
1861 The easiest way to edit the actions files is with a browser by
1862 using our browser-based editor, which can be reached from <ulink
1863 url="http://config.privoxy.org/show-status">http://config.privoxy.org/show-status</ulink>.
1864 Note: the config file option <link
1865 linkend="enable-edit-actions">enable-edit-actions</link> must be enabled for
1866 this to work. The editor allows both fine-grained control over every single
1867 feature on a per-URL basis, and easy choosing from wholesale sets of defaults
1868 like <quote>Cautious</quote>, <quote>Medium</quote> or
1869 <quote>Advanced</quote>. Warning: the <quote>Advanced</quote> setting is more
1870 aggressive, and will be more likely to cause problems for some sites.
1871 Experienced users only!
1875 If you prefer plain text editing to GUIs, you can of course also directly edit the
1876 the actions files with your favorite text editor. Look at
1877 <filename>default.action</filename> which is richly commented with many
1883 <sect2 id="actions-apply">
1884 <title>How Actions are Applied to Requests</title>
1886 Actions files are divided into sections. There are special sections,
1887 like the <quote><link linkend="aliases">alias</link></quote> sections which will
1888 be discussed later. For now let's concentrate on regular sections: They have a
1889 heading line (often split up to multiple lines for readability) which consist
1890 of a list of actions, separated by whitespace and enclosed in curly braces.
1891 Below that, there is a list of URL and tag patterns, each on a separate line.
1895 To determine which actions apply to a request, the URL of the request is
1896 compared to all URL patterns in each <quote>action file</quote>.
1897 Every time it matches, the list of applicable actions for the request is
1898 incrementally updated, using the heading of the section in which the
1899 pattern is located. The same is done again for tags and tag patterns later on.
1903 If multiple applying sections set the same action differently,
1904 the last match wins. If not, the effects are aggregated.
1905 E.g. a URL might match a regular section with a heading line of <literal>{
1906 +<link linkend="handle-as-image">handle-as-image</link> }</literal>,
1907 then later another one with just <literal>{
1908 +<link linkend="block">block</link> }</literal>, resulting
1909 in <emphasis>both</emphasis> actions to apply. And there may well be
1910 cases where you will want to combine actions together. Such a section then
1915 { +<literal>handle-as-image</literal> +<literal>block{Banner ads.}</literal> }
1916 # Block these as if they were images. Send no block page.
1918 media.example.com/.*banners
1919 .example.com/images/ads/</screen>
1922 You can trace this process for URL patterns and any given URL by visiting <ulink
1923 url="http://config.privoxy.org/show-url-info">http://config.privoxy.org/show-url-info</ulink>.
1927 Examples and more detail on this is provided in the Appendix, <link linkend="ACTIONSANAT">
1928 Troubleshooting: Anatomy of an Action</link> section.
1932 <!-- ~~~~~ New section ~~~~~ -->
1933 <sect2 id="af-patterns">
1934 <title>Patterns</title>
1936 As mentioned, <application>Privoxy</application> uses <quote>patterns</quote>
1937 to determine what <emphasis>actions</emphasis> might apply to which sites and
1938 pages your browser attempts to access. These <quote>patterns</quote> use wild
1939 card type <emphasis>pattern</emphasis> matching to achieve a high degree of
1940 flexibility. This allows one expression to be expanded and potentially match
1941 against many similar patterns.
1945 Generally, an URL pattern has the form
1946 <literal><host><port>/<path></literal>, where the
1947 <literal><host></literal>, the <literal><port></literal>
1948 and the <literal><path></literal> are optional. (This is why the special
1949 <literal>/</literal> pattern matches all URLs). Note that the protocol
1950 portion of the URL pattern (e.g. <literal>http://</literal>) should
1951 <emphasis>not</emphasis> be included in the pattern. This is assumed already!
1954 The pattern matching syntax is different for the host and path parts of
1955 the URL. The host part uses a simple globbing type matching technique,
1956 while the path part uses more flexible
1957 <ulink url="http://en.wikipedia.org/wiki/Regular_expressions"><quote>Regular
1958 Expressions</quote></ulink> (POSIX 1003.2).
1961 The port part of a pattern is a decimal port number preceded by a colon
1962 (<literal>:</literal>). If the host part contains a numerical IPv6 address,
1963 it has to be put into angle brackets
1964 (<literal><</literal>, <literal>></literal>).
1969 <term><literal>www.example.com/</literal></term>
1972 is a host-only pattern and will match any request to <literal>www.example.com</literal>,
1973 regardless of which document on that server is requested. So ALL pages in
1974 this domain would be covered by the scope of this action. Note that a
1975 simple <literal>example.com</literal> is different and would NOT match.
1980 <term><literal>www.example.com</literal></term>
1983 means exactly the same. For host-only patterns, the trailing <literal>/</literal> may
1989 <term><literal>www.example.com/index.html</literal></term>
1992 matches all the documents on <literal>www.example.com</literal>
1993 whose name starts with <literal>/index.html</literal>.
1998 <term><literal>www.example.com/index.html$</literal></term>
2001 matches only the single document <literal>/index.html</literal>
2002 on <literal>www.example.com</literal>.
2007 <term><literal>/index.html$</literal></term>
2010 matches the document <literal>/index.html</literal>, regardless of the domain,
2011 i.e. on <emphasis>any</emphasis> web server anywhere.
2016 <term><literal>/</literal></term>
2019 Matches any URL because there's no requirement for either the
2020 domain or the path to match anything.
2025 <term><literal>:8000/</literal></term>
2028 Matches any URL pointing to TCP port 8000.
2033 <term><literal>10.0.0.1/</literal></term>
2036 Matches any URL with the host address <literal>10.0.0.1</literal>.
2037 (Note that the real URL uses plain brackets, not angle brackets.)
2042 <term><literal><2001:db8::1>/</literal></term>
2045 Matches any URL with the host address <literal>2001:db8::1</literal>.
2046 (Note that the real URL uses plain brackets, not angle brackets.)
2051 <term><literal>index.html</literal></term>
2054 matches nothing, since it would be interpreted as a domain name and
2055 there is no top-level domain called <literal>.html</literal>. So its
2063 <!-- ~~~~~ New section ~~~~~ -->
2064 <sect3 id="host-pattern"><title>The Host Pattern</title>
2067 The matching of the host part offers some flexible options: if the
2068 host pattern starts or ends with a dot, it becomes unanchored at that end.
2069 The host pattern is often referred to as domain pattern as it is usually
2070 used to match domain names and not IP addresses.
2076 <term><literal>.example.com</literal></term>
2079 matches any domain with first-level domain <literal>com</literal>
2080 and second-level domain <literal>example</literal>.
2081 For example <literal>www.example.com</literal>,
2082 <literal>example.com</literal> and <literal>foo.bar.baz.example.com</literal>.
2083 Note that it wouldn't match if the second-level domain was <literal>another-example</literal>.
2088 <term><literal>www.</literal></term>
2091 matches any domain that <emphasis>STARTS</emphasis> with
2092 <literal>www.</literal> (It also matches the domain
2093 <literal>www</literal> but most of the time that doesn't matter.)
2098 <term><literal>.example.</literal></term>
2101 matches any domain that <emphasis>CONTAINS</emphasis> <literal>.example.</literal>.
2102 And, by the way, also included would be any files or documents that exist
2103 within that domain since no path limitations are specified. (Correctly
2104 speaking: It matches any FQDN that contains <literal>example</literal> as
2105 a domain.) This might be <literal>www.example.com</literal>,
2106 <literal>news.example.de</literal>, or
2107 <literal>www.example.net/cgi/testing.pl</literal> for instance. All these
2115 Additionally, there are wild-cards that you can use in the domain names
2116 themselves. These work similarly to shell globbing type wild-cards:
2117 <quote>*</quote> represents zero or more arbitrary characters (this is
2119 <ulink url="http://en.wikipedia.org/wiki/Regular_expressions"><quote>Regular
2120 Expression</quote></ulink> based syntax of <quote>.*</quote>),
2121 <quote>?</quote> represents any single character (this is equivalent to the
2122 regular expression syntax of a simple <quote>.</quote>), and you can define
2123 <quote>character classes</quote> in square brackets which is similar to
2124 the same regular expression technique. All of this can be freely mixed:
2129 <term><literal>ad*.example.com</literal></term>
2132 matches <quote>adserver.example.com</quote>,
2133 <quote>ads.example.com</quote>, etc but not <quote>sfads.example.com</quote>
2138 <term><literal>*ad*.example.com</literal></term>
2141 matches all of the above, and then some.
2146 <term><literal>.?pix.com</literal></term>
2149 matches <literal>www.ipix.com</literal>,
2150 <literal>pictures.epix.com</literal>, <literal>a.b.c.d.e.upix.com</literal> etc.
2155 <term><literal>www[1-9a-ez].example.c*</literal></term>
2158 matches <literal>www1.example.com</literal>,
2159 <literal>www4.example.cc</literal>, <literal>wwwd.example.cy</literal>,
2160 <literal>wwwz.example.com</literal> etc., but <emphasis>not</emphasis>
2161 <literal>wwww.example.com</literal>.
2168 While flexible, this is not the sophistication of full regular expression based syntax.
2173 <!-- ~ End section ~ -->
2176 <!-- ~~~~~ New section ~~~~~ -->
2177 <sect3 id="path-pattern"><title>The Path Pattern</title>
2180 <application>Privoxy</application> uses <quote>modern</quote> POSIX 1003.2
2181 <ulink url="http://en.wikipedia.org/wiki/Regular_expressions"><quote>Regular
2182 Expressions</quote></ulink> for matching the path portion (after the slash),
2183 and is thus more flexible.
2187 There is an <link linkend="regex">Appendix</link> with a brief quick-start into regular
2188 expressions, you also might want to have a look at your operating system's documentation
2189 on regular expressions (try <literal>man re_format</literal>).
2193 Note that the path pattern is automatically left-anchored at the <quote>/</quote>,
2194 i.e. it matches as if it would start with a <quote>^</quote> (regular expression speak
2195 for the beginning of a line).
2199 Please also note that matching in the path is <emphasis>CASE INSENSITIVE</emphasis>
2200 by default, but you can switch to case sensitive at any point in the pattern by using the
2201 <quote>(?-i)</quote> switch: <literal>www.example.com/(?-i)PaTtErN.*</literal> will match
2202 only documents whose path starts with <literal>PaTtErN</literal> in
2203 <emphasis>exactly</emphasis> this capitalization.
2208 <term><literal>.example.com/.*</literal></term>
2211 Is equivalent to just <quote>.example.com</quote>, since any documents
2212 within that domain are matched with or without the <quote>.*</quote>
2213 regular expression. This is redundant
2218 <term><literal>.example.com/.*/index.html$</literal></term>
2221 Will match any page in the domain of <quote>example.com</quote> that is
2222 named <quote>index.html</quote>, and that is part of some path. For
2223 example, it matches <quote>www.example.com/testing/index.html</quote> but
2224 NOT <quote>www.example.com/index.html</quote> because the regular
2225 expression called for at least two <quote>/'s</quote>, thus the path
2226 requirement. It also would match
2227 <quote>www.example.com/testing/index_html</quote>, because of the
2228 special meta-character <quote>.</quote>.
2233 <term><literal>.example.com/(.*/)?index\.html$</literal></term>
2236 This regular expression is conditional so it will match any page
2237 named <quote>index.html</quote> regardless of path which in this case can
2238 have one or more <quote>/'s</quote>. And this one must contain exactly
2239 <quote>.html</quote> (and end with that!).
2244 <term><literal>.example.com/(.*/)(ads|banners?|junk)</literal></term>
2247 This regular expression will match any path of <quote>example.com</quote>
2248 that contains any of the words <quote>ads</quote>, <quote>banner</quote>,
2249 <quote>banners</quote> (because of the <quote>?</quote>) or <quote>junk</quote>.
2250 The path does not have to end in these words, just contain them.
2251 The path has to contain at least two slashes (including the one at the beginning).
2256 <term><literal>.example.com/(.*/)(ads|banners?|junk)/.*\.(jpe?g|gif|png)$</literal></term>
2259 This is very much the same as above, except now it must end in either
2260 <quote>.jpg</quote>, <quote>.jpeg</quote>, <quote>.gif</quote> or <quote>.png</quote>. So this
2261 one is limited to common image formats.
2268 There are many, many good examples to be found in <filename>default.action</filename>,
2269 and more tutorials below in <link linkend="regex">Appendix on regular expressions</link>.
2274 <!-- ~ End section ~ -->
2277 <!-- ~~~~~ New section ~~~~~ -->
2278 <sect3 id="tag-pattern"><title>The Request Tag Pattern</title>
2281 Request tag patterns are used to change the applying actions based on the
2282 request's tags. Tags can be created based on HTTP headers with either
2283 the <link linkend="CLIENT-HEADER-TAGGER">client-header-tagger</link>
2284 or the <link linkend="SERVER-HEADER-TAGGER">server-header-tagger</link> action.
2288 Request tag patterns have to start with <quote>TAG:</quote>, so &my-app;
2289 can tell them apart from other patterns. Everything after the colon
2290 including white space, is interpreted as a regular expression with
2291 path pattern syntax, except that tag patterns aren't left-anchored
2292 automatically (&my-app; doesn't silently add a <quote>^</quote>,
2293 you have to do it yourself if you need it).
2297 To match all requests that are tagged with <quote>foo</quote>
2298 your pattern line should be <quote>TAG:^foo$</quote>,
2299 <quote>TAG:foo</quote> would work as well, but it would also
2300 match requests whose tags contain <quote>foo</quote> somewhere.
2301 <quote>TAG: foo</quote> wouldn't work as it requires white space.
2305 Sections can contain URL and request tag patterns at the same time,
2306 but request tag patterns are checked after the URL patterns and thus
2307 always overrule them, even if they are located before the URL patterns.
2311 Once a new request tag is added, Privoxy checks right away if it's matched by one
2312 of the request tag patterns and updates the action settings accordingly. As a result
2313 request tags can be used to activate other tagger actions, as long as these other
2314 taggers look for headers that haven't already be parsed.
2318 For example you could tag client requests which use the
2319 <literal>POST</literal> method,
2320 then use this tag to activate another tagger that adds a tag if cookies
2321 are sent, and then use a block action based on the cookie tag. This allows
2322 the outcome of one action, to be input into a subsequent action. However if
2323 you'd reverse the position of the described taggers, and activated the
2324 method tagger based on the cookie tagger, no method tags would be created.
2325 The method tagger would look for the request line, but at the time
2326 the cookie tag is created, the request line has already been parsed.
2330 While this is a limitation you should be aware of, this kind of
2331 indirection is seldom needed anyway and even the example doesn't
2332 make too much sense.
2337 <!-- ~~~~~ New section ~~~~~ -->
2338 <sect3 id="negative-tag-patterns"><title>The Negative Request Tag Patterns</title>
2341 To match requests that do not have a certain request tag, specify a negative tag pattern
2342 by prefixing the tag pattern line with either <quote>NO-REQUEST-TAG:</quote>
2343 or <quote>NO-RESPONSE-TAG:</quote> instead of <quote>TAG:</quote>.
2347 Negative request tag patterns created with <quote>NO-REQUEST-TAG:</quote> are checked
2348 after all client headers are scanned, the ones created with <quote>NO-RESPONSE-TAG:</quote>
2349 are checked after all server headers are scanned. In both cases all the created
2350 tags are considered.
2354 <!-- ~~~~~ New section ~~~~~ -->
2355 <sect3 id="client-tag-pattern"><title>The Client Tag Pattern</title>
2357 <!-- XXX: This section contains duplicates content from the
2358 client-specific-tag documentation. -->
2362 This is an experimental feature. The syntax is likely to change in future versions.
2367 Client tag patterns are not set based on HTTP headers but based on
2368 the client's IP address. Users can enable them themselves, but the
2369 Privoxy admin controls which tags are available and what their effect
2374 After a client-specific tag has been defined with the
2375 <link linkend="client-specific-tag">client-specific-tag</link>,
2376 directive, action sections can be activated based on the tag by using a
2377 CLIENT-TAG pattern. The CLIENT-TAG pattern is evaluated at the same priority
2378 as URL patterns, as a result the last matching pattern wins. Tags that
2379 are created based on client or server headers are evaluated later on
2380 and can overrule CLIENT-TAG and URL patterns!
2383 The tag is set for all requests that come from clients that requested
2384 it to be set. Note that "clients" are differentiated by IP address,
2385 if the IP address changes the tag has to be requested again.
2388 Clients can request tags to be set by using the CGI interface <ulink
2389 url="http://config.privoxy.org/client-tags">http://config.privoxy.org/client-tags</ulink>.
2397 # If the admin defined the client-specific-tag circumvent-blocks,
2398 # and the request comes from a client that previously requested
2399 # the tag to be set, overrule all previous +block actions that
2400 # are enabled based on URL to CLIENT-TAG patterns.
2402 CLIENT-TAG:^circumvent-blocks$
2404 # This section is not overruled because it's located after
2406 {+block{Nobody is supposed to request this.}}
2407 example.org/blocked-example-page</screen>
2413 <!-- ~ End section ~ -->
2416 <!-- ~~~~~ New section ~~~~~ -->
2418 <sect2 id="actions">
2419 <title>Actions</title>
2421 All actions are disabled by default, until they are explicitly enabled
2422 somewhere in an actions file. Actions are turned on if preceded with a
2423 <quote>+</quote>, and turned off if preceded with a <quote>-</quote>. So a
2424 <literal>+action</literal> means <quote>do that action</quote>, e.g.
2425 <literal>+block</literal> means <quote>please block URLs that match the
2426 following patterns</quote>, and <literal>-block</literal> means <quote>don't
2427 block URLs that match the following patterns, even if <literal>+block</literal>
2428 previously applied.</quote>
2432 Again, actions are invoked by placing them on a line, enclosed in curly braces and
2433 separated by whitespace, like in
2434 <literal>{+some-action -some-other-action{some-parameter}}</literal>,
2435 followed by a list of URL patterns, one per line, to which they apply.
2436 Together, the actions line and the following pattern lines make up a section
2437 of the actions file.
2441 Actions fall into three categories:
2447 Boolean, i.e the action can only be <quote>enabled</quote> or
2448 <quote>disabled</quote>. Syntax:
2451 +<replaceable class="function">name</replaceable> # enable action <replaceable class="parameter">name</replaceable>
2452 -<replaceable class="function">name</replaceable> # disable action <replaceable class="parameter">name</replaceable></screen>
2454 Example: <literal>+handle-as-image</literal>
2461 Parameterized, where some value is required in order to enable this type of action.
2465 +<replaceable class="function">name</replaceable>{<replaceable class="parameter">param</replaceable>} # enable action and set parameter to <replaceable class="parameter">param</replaceable>,
2466 # overwriting parameter from previous match if necessary
2467 -<replaceable class="function">name</replaceable> # disable action. The parameter can be omitted</screen>
2469 Note that if the URL matches multiple positive forms of a parameterized action,
2470 the last match wins, i.e. the params from earlier matches are simply ignored.
2473 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>
2479 Multi-value. These look exactly like parameterized actions,
2480 but they behave differently: If the action applies multiple times to the
2481 same URL, but with different parameters, <emphasis>all</emphasis> the parameters
2482 from <emphasis>all</emphasis> matches are remembered. This is used for actions
2483 that can be executed for the same request repeatedly, like adding multiple
2484 headers, or filtering through multiple filters. Syntax:
2487 +<replaceable class="function">name</replaceable>{<replaceable class="parameter">param</replaceable>} # enable action and add <replaceable class="parameter">param</replaceable> to the list of parameters
2488 -<replaceable class="function">name</replaceable>{<replaceable class="parameter">param</replaceable>} # remove the parameter <replaceable class="parameter">param</replaceable> from the list of parameters
2489 # If it was the last one left, disable the action.
2490 <replaceable class="parameter">-name</replaceable> # disable this action completely and remove all parameters from the list</screen>
2492 Examples: <literal>+add-header{X-Fun-Header: Some text}</literal> and
2493 <literal>+filter{html-annoyances}</literal>
2500 If nothing is specified in any actions file, no <quote>actions</quote> are
2501 taken. So in this case <application>Privoxy</application> would just be a
2502 normal, non-blocking, non-filtering proxy. You must specifically enable the
2503 privacy and blocking features you need (although the provided default actions
2504 files will give a good starting point).
2508 Later defined action sections always over-ride earlier ones of the same type.
2509 So exceptions to any rules you make, should come in the latter part of the file (or
2510 in a file that is processed later when using multiple actions files such
2511 as <filename>user.action</filename>). For multi-valued actions, the actions
2512 are applied in the order they are specified. Actions files are processed in
2513 the order they are defined in <filename>config</filename> (the default
2514 installation has three actions files). It also quite possible for any given
2515 URL to match more than one <quote>pattern</quote> (because of wildcards and
2516 regular expressions), and thus to trigger more than one set of actions! Last
2520 <!-- start actions listing -->
2522 The list of valid <application>Privoxy</application> actions are:
2526 <!-- ********************************************************** -->
2527 <!-- Please note the below defined actions use id's that are -->
2528 <!-- probably linked from other places, so please don't change. -->
2530 <!-- ********************************************************** -->
2533 <!-- ~~~~~ New section ~~~~~ -->
2535 <sect3 renderas="sect4" id="add-header">
2536 <title>add-header</title>
2540 <term>Typical use:</term>
2542 <para>Confuse log analysis, custom applications</para>
2547 <term>Effect:</term>
2550 Sends a user defined HTTP header to the web server.
2557 <!-- boolean, parameterized, Multi-value -->
2559 <para>Multi-value.</para>
2564 <term>Parameter:</term>
2567 Any string value is possible. Validity of the defined HTTP headers is not checked.
2568 It is recommended that you use the <quote><literal>X-</literal></quote> prefix
2578 This action may be specified multiple times, in order to define multiple
2579 headers. This is rarely needed for the typical user. If you don't know what
2580 <quote>HTTP headers</quote> are, you definitely don't need to worry about this
2584 Headers added by this action are not modified by other actions.
2590 <term>Example usage:</term>
2592 <screen># Add a DNT ("Do not track") header to all requests,
2593 # event to those that already have one.
2595 # This is just an example, not a recommendation.
2597 # There is no reason to believe that user-tracking websites care
2598 # about the DNT header and depending on the User-Agent, adding the
2599 # header may make user-tracking easier.
2600 {+add-header{DNT: 1}}
2608 <!-- ~~~~~ New section ~~~~~ -->
2609 <sect3 renderas="sect4" id="block">
2610 <title>block</title>
2614 <term>Typical use:</term>
2616 <para>Block ads or other unwanted content</para>
2621 <term>Effect:</term>
2624 Requests for URLs to which this action applies are blocked, i.e. the
2625 requests are trapped by &my-app; and the requested URL is never retrieved,
2626 but is answered locally with a substitute page or image, as determined by
2628 linkend="handle-as-image">handle-as-image</link></literal>,
2630 linkend="set-image-blocker">set-image-blocker</link></literal>, and
2632 linkend="handle-as-empty-document">handle-as-empty-document</link></literal> actions.
2640 <!-- boolean, parameterized, Multi-value -->
2642 <para>Parameterized.</para>
2647 <term>Parameter:</term>
2649 <para>A block reason that should be given to the user.</para>
2657 <application>Privoxy</application> sends a special <quote>BLOCKED</quote> page
2658 for requests to blocked pages. This page contains the block reason given as
2659 parameter, a link to find out why the block action applies, and a click-through
2660 to the blocked content (the latter only if the force feature is available and
2664 A very important exception occurs if <emphasis>both</emphasis>
2665 <literal>block</literal> and <literal><link linkend="handle-as-image">handle-as-image</link></literal>,
2666 apply to the same request: it will then be replaced by an image. If
2667 <literal><link linkend="set-image-blocker">set-image-blocker</link></literal>
2668 (see below) also applies, the type of image will be determined by its parameter,
2669 if not, the standard checkerboard pattern is sent.
2672 It is important to understand this process, in order
2673 to understand how <application>Privoxy</application> deals with
2674 ads and other unwanted content. Blocking is a core feature, and one
2675 upon which various other features depend.
2678 The <literal><link linkend="filter">filter</link></literal>
2679 action can perform a very similar task, by <quote>blocking</quote>
2680 banner images and other content through rewriting the relevant URLs in the
2681 document's HTML source, so they don't get requested in the first place.
2682 Note that this is a totally different technique, and it's easy to confuse the two.
2688 <term>Example usage (section):</term>
2690 <screen>{+block{No nasty stuff for you.}}
2691 # Block and replace with "blocked" page
2692 .nasty-stuff.example.com
2694 {+block{Doubleclick banners.} +handle-as-image}
2695 # Block and replace with image
2699 {+block{Layered ads.} +handle-as-empty-document}
2700 # Block and then ignore
2701 adserver.example.net/.*\.js$</screen>
2710 <!-- ~~~~~ New section ~~~~~ -->
2711 <sect3 renderas="sect4" id="change-x-forwarded-for">
2712 <title>change-x-forwarded-for</title>
2716 <term>Typical use:</term>
2718 <para>Improve privacy by not forwarding the source of the request in the HTTP headers.</para>
2723 <term>Effect:</term>
2726 Deletes the <quote>X-Forwarded-For:</quote> HTTP header from the client request,
2734 <!-- Boolean, Parameterized, Multi-value -->
2736 <para>Parameterized.</para>
2741 <term>Parameter:</term>
2745 <para><quote>block</quote> to delete the header.</para>
2749 <quote>add</quote> to create the header (or append
2750 the client's IP address to an already existing one).
2761 It is safe and recommended to use <literal>block</literal>.
2764 Forwarding the source address of the request may make
2765 sense in some multi-user setups but is also a privacy risk.
2770 <term>Example usage:</term>
2772 <screen>+change-x-forwarded-for{block}</screen>
2778 <!-- ~~~~~ New section ~~~~~ -->
2779 <sect3 renderas="sect4" id="client-header-filter">
2780 <title>client-header-filter</title>
2784 <term>Typical use:</term>
2787 Rewrite or remove single client headers.
2793 <term>Effect:</term>
2796 All client headers to which this action applies are filtered on-the-fly through
2797 the specified regular expression based substitutions.
2804 <!-- boolean, parameterized, Multi-value -->
2806 <para>Multi-value.</para>
2811 <term>Parameter:</term>
2814 The name of a client-header filter, as defined in one of the
2815 <link linkend="filter-file">filter files</link>.
2824 Client-header filters are applied to each header on its own, not to
2825 all at once. This makes it easier to diagnose problems, but on the downside
2826 you can't write filters that only change header x if header y's value is z.
2827 You can do that by using tags though.
2830 Client-header filters are executed after the other header actions have finished
2831 and use their output as input.
2834 If the request URI gets changed, &my-app; will detect that and use the new
2835 one. This can be used to rewrite the request destination behind the client's
2836 back, for example to specify a Tor exit relay for certain requests.
2839 Please refer to the <link linkend="filter-file">filter file chapter</link>
2840 to learn which client-header filters are available by default, and how to
2848 <term>Example usage (section):</term>
2851 # Hide Tor exit notation in Host and Referer Headers
2852 {+client-header-filter{hide-tor-exit-notation}}
2862 <!-- ~~~~~ New section ~~~~~ -->
2863 <sect3 renderas="sect4" id="client-header-tagger">
2864 <title>client-header-tagger</title>
2868 <term>Typical use:</term>
2871 Block requests based on their headers.
2877 <term>Effect:</term>
2880 Client headers to which this action applies are filtered on-the-fly through
2881 the specified regular expression based substitutions, the result is used as
2889 <!-- boolean, parameterized, Multi-value -->
2891 <para>Multi-value.</para>
2896 <term>Parameter:</term>
2899 The name of a client-header tagger, as defined in one of the
2900 <link linkend="filter-file">filter files</link>.
2909 Client-header taggers are applied to each header on its own,
2910 and as the header isn't modified, each tagger <quote>sees</quote>
2914 Client-header taggers are the first actions that are executed
2915 and their tags can be used to control every other action.
2921 <term>Example usage (section):</term>
2924 # Tag every request with the User-Agent header
2925 {+client-header-tagger{user-agent}}
2928 # Tagging itself doesn't change the action
2929 # settings, sections with TAG patterns do:
2931 # If it's a download agent, use a different forwarding proxy,
2932 # show the real User-Agent and make sure resume works.
2933 {+forward-override{forward-socks5 10.0.0.2:2222 .} \
2934 -hide-if-modified-since \
2935 -overwrite-last-modified \
2940 TAG:^User-Agent: NetBSD-ftp/
2941 TAG:^User-Agent: Novell ZYPP Installer
2942 TAG:^User-Agent: RPM APT-HTTP/
2943 TAG:^User-Agent: fetch libfetch/
2944 TAG:^User-Agent: Ubuntu APT-HTTP/
2945 TAG:^User-Agent: MPlayer/
2949 # Tag all requests with the Range header set
2950 {+client-header-tagger{range-requests}}
2953 # Disable filtering for the tagged requests.
2955 # With filtering enabled Privoxy would remove the Range headers
2956 # to be able to filter the whole response. The downside is that
2957 # it prevents clients from resuming downloads or skipping over
2958 # parts of multimedia files.
2959 {-filter -deanimate-gifs}
2964 # Tag all requests with the client IP address
2966 # (Technically the client IP address isn't included in the
2967 # client headers but client-header taggers can set it anyway.
2968 # For details see the tagger in default.filter)
2969 {+client-header-tagger{client-ip-address}}
2972 # Change forwarding settings for requests coming from address 10.0.0.1
2973 {+forward-override{forward-socks5 127.0.1.2:2222 .}}
2974 TAG:^IP-ADDRESS: 10\.0\.0\.1$
2983 <!-- ~~~~~ New section ~~~~~ -->
2984 <sect3 renderas="sect4" id="content-type-overwrite">
2985 <title>content-type-overwrite</title>
2989 <term>Typical use:</term>
2991 <para>Stop useless download menus from popping up, or change the browser's rendering mode</para>
2996 <term>Effect:</term>
2999 Replaces the <quote>Content-Type:</quote> HTTP server header.
3006 <!-- Boolean, Parameterized, Multi-value -->
3008 <para>Parameterized.</para>
3013 <term>Parameter:</term>
3025 The <quote>Content-Type:</quote> HTTP server header is used by the
3026 browser to decide what to do with the document. The value of this
3027 header can cause the browser to open a download menu instead of
3028 displaying the document by itself, even if the document's format is
3029 supported by the browser.
3032 The declared content type can also affect which rendering mode
3033 the browser chooses. If XHTML is delivered as <quote>text/html</quote>,
3034 many browsers treat it as yet another broken HTML document.
3035 If it is send as <quote>application/xml</quote>, browsers with
3036 XHTML support will only display it, if the syntax is correct.
3039 If you see a web site that proudly uses XHTML buttons, but sets
3040 <quote>Content-Type: text/html</quote>, you can use &my-app;
3041 to overwrite it with <quote>application/xml</quote> and validate
3042 the web master's claim inside your XHTML-supporting browser.
3043 If the syntax is incorrect, the browser will complain loudly.
3046 You can also go the opposite direction: if your browser prints
3047 error messages instead of rendering a document falsely declared
3048 as XHTML, you can overwrite the content type with
3049 <quote>text/html</quote> and have it rendered as broken HTML document.
3052 By default <literal>content-type-overwrite</literal> only replaces
3053 <quote>Content-Type:</quote> headers that look like some kind of text.
3054 If you want to overwrite it unconditionally, you have to combine it with
3055 <literal><link linkend="force-text-mode">force-text-mode</link></literal>.
3056 This limitation exists for a reason, think twice before circumventing it.
3059 Most of the time it's easier to replace this action with a custom
3060 <literal><link linkend="server-header-filter">server-header filter</link></literal>.
3061 It allows you to activate it for every document of a certain site and it will still
3062 only replace the content types you aimed at.
3065 Of course you can apply <literal>content-type-overwrite</literal>
3066 to a whole site and then make URL based exceptions, but it's a lot
3067 more work to get the same precision.
3073 <term>Example usage (sections):</term>
3075 <screen># Check if www.example.net/ really uses valid XHTML
3076 { +content-type-overwrite{application/xml} }
3079 # but leave the content type unmodified if the URL looks like a style sheet
3080 {-content-type-overwrite}
3081 www.example.net/.*\.css$
3082 www.example.net/.*style
3090 <!-- ~~~~~ New section ~~~~~ -->
3091 <sect3 renderas="sect4" id="crunch-client-header">
3095 <title>crunch-client-header</title>
3099 <term>Typical use:</term>
3101 <para>Remove a client header <application>Privoxy</application> has no dedicated action for.</para>
3106 <term>Effect:</term>
3109 Deletes every header sent by the client that contains the string the user supplied as parameter.
3116 <!-- Boolean, Parameterized, Multi-value -->
3118 <para>Parameterized.</para>
3123 <term>Parameter:</term>
3135 This action allows you to block client headers for which no dedicated
3136 <application>Privoxy</application> action exists.
3137 <application>Privoxy</application> will remove every client header that
3138 contains the string you supplied as parameter.
3141 Regular expressions are <emphasis>not supported</emphasis> and you can't
3142 use this action to block different headers in the same request, unless
3143 they contain the same string.
3146 <literal>crunch-client-header</literal> is only meant for quick tests.
3147 If you have to block several different headers, or only want to modify
3148 parts of them, you should use a
3149 <literal><link linkend="client-header-filter">client-header filter</link></literal>.
3153 Don't block any header without understanding the consequences.
3160 <term>Example usage (section):</term>
3162 <screen># Block the non-existent "Privacy-Violation:" client header
3163 { +crunch-client-header{Privacy-Violation:} }
3172 <!-- ~~~~~ New section ~~~~~ -->
3173 <sect3 renderas="sect4" id="crunch-if-none-match">
3174 <title>crunch-if-none-match</title>
3180 <term>Typical use:</term>
3182 <para>Prevent yet another way to track the user's steps between sessions.</para>
3187 <term>Effect:</term>
3190 Deletes the <quote>If-None-Match:</quote> HTTP client header.
3197 <!-- Boolean, Parameterized, Multi-value -->
3199 <para>Boolean.</para>
3204 <term>Parameter:</term>
3216 Removing the <quote>If-None-Match:</quote> HTTP client header
3217 is useful for filter testing, where you want to force a real
3218 reload instead of getting status code <quote>304</quote> which
3219 would cause the browser to use a cached copy of the page.
3222 It is also useful to make sure the header isn't used as a cookie
3223 replacement (unlikely but possible).
3226 Blocking the <quote>If-None-Match:</quote> header shouldn't cause any
3227 caching problems, as long as the <quote>If-Modified-Since:</quote> header
3228 isn't blocked or missing as well.
3231 It is recommended to use this action together with
3232 <literal><link linkend="hide-if-modified-since">hide-if-modified-since</link></literal>
3234 <literal><link linkend="overwrite-last-modified">overwrite-last-modified</link></literal>.
3240 <term>Example usage (section):</term>
3242 <screen># Let the browser revalidate cached documents but don't
3243 # allow the server to use the revalidation headers for user tracking.
3244 {+hide-if-modified-since{-60} \
3245 +overwrite-last-modified{randomize} \
3246 +crunch-if-none-match}
3254 <!-- ~~~~~ New section ~~~~~ -->
3255 <sect3 renderas="sect4" id="crunch-incoming-cookies">
3256 <title>crunch-incoming-cookies</title>
3260 <term>Typical use:</term>
3263 Prevent the web server from setting HTTP cookies on your system
3269 <term>Effect:</term>
3272 Deletes any <quote>Set-Cookie:</quote> HTTP headers from server replies.
3279 <!-- Boolean, Parameterized, Multi-value -->
3281 <para>Boolean.</para>
3286 <term>Parameter:</term>
3298 This action is only concerned with <emphasis>incoming</emphasis> HTTP cookies. For
3299 <emphasis>outgoing</emphasis> HTTP cookies, use
3300 <literal><link linkend="crunch-outgoing-cookies">crunch-outgoing-cookies</link></literal>.
3301 Use <emphasis>both</emphasis> to disable HTTP cookies completely.
3304 It makes <emphasis>no sense at all</emphasis> to use this action in conjunction
3305 with the <literal><link linkend="session-cookies-only">session-cookies-only</link></literal> action,
3306 since it would prevent the session cookies from being set. See also
3307 <literal><link linkend="filter-content-cookies">filter-content-cookies</link></literal>.
3313 <term>Example usage:</term>
3315 <screen>+crunch-incoming-cookies</screen>
3322 <!-- ~~~~~ New section ~~~~~ -->
3323 <sect3 renderas="sect4" id="crunch-server-header">
3324 <title>crunch-server-header</title>
3330 <term>Typical use:</term>
3332 <para>Remove a server header <application>Privoxy</application> has no dedicated action for.</para>
3337 <term>Effect:</term>
3340 Deletes every header sent by the server that contains the string the user supplied as parameter.
3347 <!-- Boolean, Parameterized, Multi-value -->
3349 <para>Parameterized.</para>
3354 <term>Parameter:</term>
3366 This action allows you to block server headers for which no dedicated
3367 <application>Privoxy</application> action exists. <application>Privoxy</application>
3368 will remove every server header that contains the string you supplied as parameter.
3371 Regular expressions are <emphasis>not supported</emphasis> and you can't
3372 use this action to block different headers in the same request, unless
3373 they contain the same string.
3376 <literal>crunch-server-header</literal> is only meant for quick tests.
3377 If you have to block several different headers, or only want to modify
3378 parts of them, you should use a custom
3379 <literal><link linkend="server-header-filter">server-header filter</link></literal>.
3383 Don't block any header without understanding the consequences.
3390 <term>Example usage (section):</term>
3392 <screen># Crunch server headers that try to prevent caching
3393 { +crunch-server-header{no-cache} }
3401 <!-- ~~~~~ New section ~~~~~ -->
3402 <sect3 renderas="sect4" id="crunch-outgoing-cookies">
3403 <title>crunch-outgoing-cookies</title>
3407 <term>Typical use:</term>
3410 Prevent the web server from reading any HTTP cookies from your system
3416 <term>Effect:</term>
3419 Deletes any <quote>Cookie:</quote> HTTP headers from client requests.
3426 <!-- Boolean, Parameterized, Multi-value -->
3428 <para>Boolean.</para>
3433 <term>Parameter:</term>
3445 This action is only concerned with <emphasis>outgoing</emphasis> HTTP cookies. For
3446 <emphasis>incoming</emphasis> HTTP cookies, use
3447 <literal><link linkend="crunch-incoming-cookies">crunch-incoming-cookies</link></literal>.
3448 Use <emphasis>both</emphasis> to disable HTTP cookies completely.
3451 It makes <emphasis>no sense at all</emphasis> to use this action in conjunction
3452 with the <literal><link linkend="session-cookies-only">session-cookies-only</link></literal> action,
3453 since it would prevent the session cookies from being read.
3459 <term>Example usage:</term>
3461 <screen>+crunch-outgoing-cookies</screen>
3469 <!-- ~~~~~ New section ~~~~~ -->
3470 <sect3 renderas="sect4" id="deanimate-gifs">
3471 <title>deanimate-gifs</title>
3475 <term>Typical use:</term>
3477 <para>Stop those annoying, distracting animated GIF images.</para>
3482 <term>Effect:</term>
3485 De-animate GIF animations, i.e. reduce them to their first or last image.
3492 <!-- boolean, parameterized, Multi-value -->
3494 <para>Parameterized.</para>
3499 <term>Parameter:</term>
3502 <quote>last</quote> or <quote>first</quote>
3511 This will also shrink the images considerably (in bytes, not pixels!). If
3512 the option <quote>first</quote> is given, the first frame of the animation
3513 is used as the replacement. If <quote>last</quote> is given, the last
3514 frame of the animation is used instead, which probably makes more sense for
3515 most banner animations, but also has the risk of not showing the entire
3516 last frame (if it is only a delta to an earlier frame).
3519 You can safely use this action with patterns that will also match non-GIF
3520 objects, because no attempt will be made at anything that doesn't look like
3527 <term>Example usage:</term>
3529 <screen>+deanimate-gifs{last}</screen>
3535 <!-- ~~~~~ New section ~~~~~ -->
3536 <sect3 renderas="sect4" id="downgrade-http-version">
3537 <title>downgrade-http-version</title>
3541 <term>Typical use:</term>
3543 <para>Work around (very rare) problems with HTTP/1.1</para>
3548 <term>Effect:</term>
3551 Downgrades HTTP/1.1 client requests and server replies to HTTP/1.0.
3558 <!-- boolean, parameterized, Multi-value -->
3560 <para>Boolean.</para>
3565 <term>Parameter:</term>
3577 This is a left-over from the time when <application>Privoxy</application>
3578 didn't support important HTTP/1.1 features well. It is left here for the
3579 unlikely case that you experience HTTP/1.1-related problems with some server
3583 Note that enabling this action is only a workaround. It should not
3584 be enabled for sites that work without it. While it shouldn't break
3585 any pages, it has an (usually negative) performance impact.
3588 If you come across a site where enabling this action helps, please report it,
3589 so the cause of the problem can be analyzed. If the problem turns out to be
3590 caused by a bug in <application>Privoxy</application> it should be
3591 fixed so the following release works without the work around.
3597 <term>Example usage (section):</term>
3599 <screen>{+downgrade-http-version}
3600 problem-host.example.com</screen>
3607 <!-- ~~~~~ New section ~~~~~ -->
3608 <sect3 renderas="sect4" id="external-filter">
3609 <title>external-filter</title>
3613 <term>Typical use:</term>
3615 <para>Modify content using a programming language of your choice.</para>
3620 <term>Effect:</term>
3623 All instances of text-based type, most notably HTML and JavaScript, to which
3624 this action applies, can be filtered on-the-fly through the specified external
3626 By default plain text documents are exempted from filtering, because web
3627 servers often use the <literal>text/plain</literal> MIME type for all files
3628 whose type they don't know.)
3635 <!-- boolean, parameterized, Multi-value -->
3637 <para>Multi-value.</para>
3642 <term>Parameter:</term>
3645 The name of an external content filter, as defined in the
3646 <link linkend="filter-file">filter file</link>.
3647 External filters can be defined in one or more files as defined by the
3648 <literal><link linkend="filterfile">filterfile</link></literal>
3649 option in the <link linkend="config">config file</link>.
3652 When used in its negative form,
3653 and without parameters, <emphasis>all</emphasis> filtering with external
3654 filters is completely disabled.
3663 External filters are scripts or programs that can modify the content in
3664 case common <literal><link linkend="filter">filters</link></literal>
3665 aren't powerful enough. With the exception that this action doesn't
3666 use pcrs-based filters, the notes in the
3667 <literal><link linkend="filter">filter</link></literal> section apply.
3671 Currently external filters are executed with &my-app;'s privileges.
3672 Only use external filters you understand and trust.
3676 This feature is experimental, the <literal><link
3677 linkend="external-filter-syntax">syntax</link></literal>
3678 may change in the future.
3685 <term>Example usage:</term>
3687 <screen>+external-filter{fancy-filter}</screen>
3693 <!-- ~~~~~ New section ~~~~~ -->
3694 <sect3 renderas="sect4" id="fast-redirects">
3695 <title>fast-redirects</title>
3699 <term>Typical use:</term>
3701 <para>Fool some click-tracking scripts and speed up indirect links.</para>
3706 <term>Effect:</term>
3709 Detects redirection URLs and redirects the browser without contacting
3710 the redirection server first.
3717 <!-- boolean, parameterized, Multi-value -->
3719 <para>Parameterized.</para>
3724 <term>Parameter:</term>
3729 <quote>simple-check</quote> to just search for the string <quote>http://</quote>
3730 to detect redirection URLs.
3735 <quote>check-decoded-url</quote> to decode URLs (if necessary) before searching
3736 for redirection URLs.
3747 Many sites, like yahoo.com, don't just link to other sites. Instead, they
3748 will link to some script on their own servers, giving the destination as a
3749 parameter, which will then redirect you to the final target. URLs
3750 resulting from this scheme typically look like:
3751 <quote>http://www.example.org/click-tracker.cgi?target=http%3a//www.example.net/</quote>.
3754 Sometimes, there are even multiple consecutive redirects encoded in the
3755 URL. These redirections via scripts make your web browsing more traceable,
3756 since the server from which you follow such a link can see where you go
3757 to. Apart from that, valuable bandwidth and time is wasted, while your
3758 browser asks the server for one redirect after the other. Plus, it feeds
3762 This feature is currently not very smart and is scheduled for improvement.
3763 If it is enabled by default, you will have to create some exceptions to
3764 this action. It can lead to failures in several ways:
3767 Not every URLs with other URLs as parameters is evil.
3768 Some sites offer a real service that requires this information to work.
3769 For example a validation service needs to know, which document to validate.
3770 <literal>fast-redirects</literal> assumes that every URL parameter that
3771 looks like another URL is a redirection target, and will always redirect to
3772 the last one. Most of the time the assumption is correct, but if it isn't,
3773 the user gets redirected anyway.
3776 Another failure occurs if the URL contains other parameters after the URL parameter.
3778 <quote>http://www.example.org/?redirect=http%3a//www.example.net/&foo=bar</quote>.
3779 contains the redirection URL <quote>http://www.example.net/</quote>,
3780 followed by another parameter. <literal>fast-redirects</literal> doesn't know that
3781 and will cause a redirect to <quote>http://www.example.net/&foo=bar</quote>.
3782 Depending on the target server configuration, the parameter will be silently ignored
3783 or lead to a <quote>page not found</quote> error. You can prevent this problem by
3784 first using the <literal><link linkend="redirect">redirect</link></literal> action
3785 to remove the last part of the URL, but it requires a little effort.
3788 To detect a redirection URL, <literal>fast-redirects</literal> only
3789 looks for the string <quote>http://</quote>, either in plain text
3790 (invalid but often used) or encoded as <quote>http%3a//</quote>.
3791 Some sites use their own URL encoding scheme, encrypt the address
3792 of the target server or replace it with a database id. In theses cases
3793 <literal>fast-redirects</literal> is fooled and the request reaches the
3794 redirection server where it probably gets logged.
3800 <term>Example usage:</term>
3803 { +fast-redirects{simple-check} }
3806 { +fast-redirects{check-decoded-url} }
3807 another.example.com/testing</screen>
3815 <!-- ~~~~~ New section ~~~~~ -->
3816 <sect3 renderas="sect4" id="filter">
3817 <title>filter</title>
3821 <term>Typical use:</term>
3823 <para>Get rid of HTML and JavaScript annoyances, banner advertisements (by size),
3824 do fun text replacements, add personalized effects, etc.</para>
3829 <term>Effect:</term>
3832 All instances of text-based type, most notably HTML and JavaScript, to which
3833 this action applies, can be filtered on-the-fly through the specified regular
3834 expression based substitutions. (Note: as of version 3.0.3 plain text documents
3835 are exempted from filtering, because web servers often use the
3836 <literal>text/plain</literal> MIME type for all files whose type they don't know.)
3843 <!-- boolean, parameterized, Multi-value -->
3845 <para>Multi-value.</para>
3850 <term>Parameter:</term>
3853 The name of a content filter, as defined in the <link linkend="filter-file">filter file</link>.
3854 Filters can be defined in one or more files as defined by the
3855 <literal><link linkend="filterfile">filterfile</link></literal>
3856 option in the <link linkend="config">config file</link>.
3857 <filename>default.filter</filename> is the collection of filters
3858 supplied by the developers. Locally defined filters should go
3859 in their own file, such as <filename>user.filter</filename>.
3862 When used in its negative form,
3863 and without parameters, <emphasis>all</emphasis> filtering is completely disabled.
3872 For your convenience, there are a number of pre-defined filters available
3873 in the distribution filter file that you can use. See the examples below for
3877 Filtering requires buffering the page content, which may appear to
3878 slow down page rendering since nothing is displayed until all content has
3879 passed the filters. (The total time until the page is completely rendered
3880 doesn't change much, but it may be perceived as slower since the page is
3881 not incrementally displayed.)
3882 This effect will be more noticeable on slower connections.
3885 <quote>Rolling your own</quote>
3886 filters requires a knowledge of
3887 <ulink url="http://en.wikipedia.org/wiki/Regular_expressions"><quote>Regular
3888 Expressions</quote></ulink> and
3889 <ulink url="http://en.wikipedia.org/wiki/Html"><quote>HTML</quote></ulink>.
3890 This is very powerful feature, and potentially very intrusive.
3891 Filters should be used with caution, and where an equivalent
3892 <quote>action</quote> is not available.
3895 The amount of data that can be filtered is limited to the
3896 <literal><link linkend="buffer-limit">buffer-limit</link></literal>
3897 option in the main <link linkend="config">config file</link>. The
3898 default is 4096 KB (4 Megs). Once this limit is exceeded, the buffered
3899 data, and all pending data, is passed through unfiltered.
3902 Inappropriate MIME types, such as zipped files, are not filtered at all.
3903 (Again, only text-based types except plain text). Encrypted SSL data
3904 (from HTTPS servers) cannot be filtered either, since this would violate
3905 the integrity of the secure transaction. In some situations it might
3906 be necessary to protect certain text, like source code, from filtering
3907 by defining appropriate <literal>-filter</literal> exceptions.
3910 Compressed content can't be filtered either, but if &my-app;
3911 is compiled with zlib support and a supported compression algorithm
3912 is used (gzip or deflate), &my-app; can first decompress the content
3916 If you use a &my-app; version without zlib support, but want filtering to work on
3917 as much documents as possible, even those that would normally be sent compressed,
3918 you must use the <literal><link linkend="prevent-compression">prevent-compression</link></literal>
3919 action in conjunction with <literal>filter</literal>.
3922 Content filtering can achieve some of the same effects as the
3923 <literal><link linkend="block">block</link></literal>
3924 action, i.e. it can be used to block ads and banners. But the mechanism
3925 works quite differently. One effective use, is to block ad banners
3926 based on their size (see below), since many of these seem to be somewhat
3930 <link linkend="contact">Feedback</link> with suggestions for new or
3931 improved filters is particularly welcome!
3934 The below list has only the names and a one-line description of each
3935 predefined filter. There are <link linkend="predefined-filters">more
3936 verbose explanations</link> of what these filters do in the <link
3937 linkend="filter-file">filter file chapter</link>.
3943 <term>Example usage (with filters from the distribution <filename>default.filter</filename> file).
3944 See <link linkend="PREDEFINED-FILTERS">the Predefined Filters section</link> for
3945 more explanation on each:</term>
3948 <anchor id="filter-js-annoyances">
3950 <screen>+filter{js-annoyances} # Get rid of particularly annoying JavaScript abuse.</screen>
3952 <anchor id="filter-js-events">
3954 <screen>+filter{js-events} # Kill JavaScript event bindings and timers (Radically destructive! Only for extra nasty sites).</screen>
3956 <anchor id="filter-html-annoyances">
3958 <screen>+filter{html-annoyances} # Get rid of particularly annoying HTML abuse.</screen>
3960 <anchor id="filter-content-cookies">
3962 <screen>+filter{content-cookies} # Kill cookies that come in the HTML or JS content.</screen>
3964 <anchor id="filter-refresh-tags">
3966 <screen>+filter{refresh-tags} # Kill automatic refresh tags if refresh time is larger than 9 seconds.</screen>
3968 <anchor id="filter-unsolicited-popups">
3970 <screen>+filter{unsolicited-popups} # Disable only unsolicited pop-up windows.</screen>
3972 <anchor id="filter-all-popups">
3974 <screen>+filter{all-popups} # Kill all popups in JavaScript and HTML.</screen>
3976 <anchor id="filter-img-reorder">
3978 <screen>+filter{img-reorder} # Reorder attributes in <img> tags to make the banners-by-* filters more effective.</screen>
3980 <anchor id="filter-banners-by-size">
3982 <screen>+filter{banners-by-size} # Kill banners by size.</screen>
3984 <anchor id="filter-banners-by-link">
3986 <screen>+filter{banners-by-link} # Kill banners by their links to known clicktrackers.</screen>
3988 <anchor id="filter-webbugs">
3990 <screen>+filter{webbugs} # Squish WebBugs (1x1 invisible GIFs used for user tracking).</screen>
3992 <anchor id="filter-tiny-textforms">
3994 <screen>+filter{tiny-textforms} # Extend those tiny textareas up to 40x80 and kill the hard wrap.</screen>
3996 <anchor id="filter-jumping-windows">
3998 <screen>+filter{jumping-windows} # Prevent windows from resizing and moving themselves.</screen>
4000 <anchor id="filter-frameset-borders">
4002 <screen>+filter{frameset-borders} # Give frames a border and make them resizable.</screen>
4004 <anchor id="filter-iframes">
4006 <screen>+filter{iframes} # Removes all detected iframes. Should only be enabled for individual sites.</screen>
4008 <anchor id="filter-demoronizer">
4010 <screen>+filter{demoronizer} # Fix MS's non-standard use of standard charsets.</screen>
4012 <anchor id="filter-shockwave-flash">
4014 <screen>+filter{shockwave-flash} # Kill embedded Shockwave Flash objects.</screen>
4016 <anchor id="filter-quicktime-kioskmode">
4018 <screen>+filter{quicktime-kioskmode} # Make Quicktime movies saveable.</screen>
4020 <anchor id="filter-fun">
4022 <screen>+filter{fun} # Text replacements for subversive browsing fun!</screen>
4024 <anchor id="filter-crude-parental">
4026 <screen>+filter{crude-parental} # Crude parental filtering. Note that this filter doesn't work reliably.</screen>
4028 <anchor id="filter-ie-exploits">
4030 <screen>+filter{ie-exploits} # Disable some known Internet Explorer bug exploits.</screen>
4032 <anchor id="filter-site-specifics">
4034 <screen>+filter{site-specifics} # Cure for site-specific problems. Don't apply generally!</screen>
4036 <anchor id="filter-no-ping">
4038 <screen>+filter{no-ping} # Removes non-standard ping attributes in <a> and <area> tags.</screen>
4040 <anchor id="filter-google">
4042 <screen>+filter{google} # CSS-based block for Google text ads. Also removes a width limitation and the toolbar advertisement.</screen>
4044 <anchor id="filter-yahoo">
4046 <screen>+filter{yahoo} # CSS-based block for Yahoo text ads. Also removes a width limitation.</screen>
4048 <anchor id="filter-msn">
4050 <screen>+filter{msn} # CSS-based block for MSN text ads. Also removes tracking URLs and a width limitation.</screen>
4052 <anchor id="filter-blogspot">
4054 <screen>+filter{blogspot} # Cleans up some Blogspot blogs. Read the fine print before using this.</screen>
4061 <!-- ~~~~~ New section ~~~~~ -->
4062 <sect3 renderas="sect4" id="force-text-mode">
4063 <title>force-text-mode</title>
4069 <term>Typical use:</term>
4071 <para>Force <application>Privoxy</application> to treat a document as if it was in some kind of <emphasis>text</emphasis> format. </para>
4076 <term>Effect:</term>
4079 Declares a document as text, even if the <quote>Content-Type:</quote> isn't detected as such.
4086 <!-- Boolean, Parameterized, Multi-value -->
4088 <para>Boolean.</para>
4093 <term>Parameter:</term>
4105 As explained <literal><link linkend="filter">above</link></literal>,
4106 <application>Privoxy</application> tries to only filter files that are
4107 in some kind of text format. The same restrictions apply to
4108 <literal><link linkend="content-type-overwrite">content-type-overwrite</link></literal>.
4109 <literal>force-text-mode</literal> declares a document as text,
4110 without looking at the <quote>Content-Type:</quote> first.
4114 Think twice before activating this action. Filtering binary data
4115 with regular expressions can cause file damage.
4122 <term>Example usage:</term>
4133 <!-- ~~~~~ New section ~~~~~ -->
4134 <sect3 renderas="sect4" id="forward-override">
4135 <title>forward-override</title>
4141 <term>Typical use:</term>
4143 <para>Change the forwarding settings based on User-Agent or request origin</para>
4148 <term>Effect:</term>
4151 Overrules the forward directives in the configuration file.
4158 <!-- Boolean, Parameterized, Multi-value -->
4160 <para>Parameterized.</para>
4165 <term>Parameter:</term>
4169 <para><quote>forward .</quote> to use a direct connection without any additional proxies.</para>
4173 <quote>forward 127.0.0.1:8123</quote> to use the HTTP proxy listening at 127.0.0.1 port 8123.
4178 <quote>forward-socks4a 127.0.0.1:9050 .</quote> to use the socks4a proxy listening at
4179 127.0.0.1 port 9050. Replace <quote>forward-socks4a</quote> with <quote>forward-socks4</quote>
4180 to use a socks4 connection (with local DNS resolution) instead, use <quote>forward-socks5</quote>
4181 for socks5 connections (with remote DNS resolution).
4186 <quote>forward-socks4a 127.0.0.1:9050 proxy.example.org:8000</quote> to use the socks4a proxy
4187 listening at 127.0.0.1 port 9050 to reach the HTTP proxy listening at proxy.example.org port 8000.
4188 Replace <quote>forward-socks4a</quote> with <quote>forward-socks4</quote> to use a socks4 connection
4189 (with local DNS resolution) instead, use <quote>forward-socks5</quote>
4190 for socks5 connections (with remote DNS resolution).
4195 <quote>forward-webserver 127.0.0.1:80</quote> to use the HTTP
4196 server listening at 127.0.0.1 port 80 without adjusting the
4200 This makes it more convenient to use Privoxy to make
4201 existing websites available as onion services as well.
4204 Many websites serve content with hardcoded URLs and
4205 can't be easily adjusted to change the domain based
4206 on the one used by the client.
4209 Putting Privoxy between Tor and the webserver (or an stunnel
4210 that forwards to the webserver) allows to rewrite headers and
4211 content to make client and server happy at the same time.
4214 Using Privoxy for webservers that are only reachable through
4215 onion addresses and whose location is supposed to be secret
4216 is not recommended and should not be necessary anyway.
4227 This action takes parameters similar to the
4228 <link linkend="forwarding">forward</link> directives in the configuration
4229 file, but without the URL pattern. It can be used as replacement, but normally it's only
4230 used in cases where matching based on the request URL isn't sufficient.
4234 Please read the description for the <link linkend="forwarding">forward</link> directives before
4235 using this action. Forwarding to the wrong people will reduce your privacy and increase the
4236 chances of man-in-the-middle attacks.
4239 If the ports are missing or invalid, default values will be used. This might change
4240 in the future and you shouldn't rely on it. Otherwise incorrect syntax causes Privoxy
4241 to exit. Due to design limitations, invalid parameter syntax isn't detected until the
4242 action is used the first time.
4245 Use the <ulink url="http://config.privoxy.org/show-url-info">show-url-info CGI page</ulink>
4246 to verify that your forward settings do what you thought the do.
4253 <term>Example usage:</term>
4256 # Use an ssh tunnel for requests previously tagged as
4257 # <quote>User-Agent: fetch libfetch/2.0</quote> and make sure
4258 # resuming downloads continues to work.
4260 # This way you can continue to use Tor for your normal browsing,
4261 # without overloading the Tor network with your FreeBSD ports updates
4262 # or downloads of bigger files like ISOs.
4264 # Note that HTTP headers are easy to fake and therefore their
4265 # values are as (un)trustworthy as your clients and users.
4266 {+forward-override{forward-socks5 10.0.0.2:2222 .} \
4267 -hide-if-modified-since \
4268 -overwrite-last-modified \
4270 TAG:^User-Agent: fetch libfetch/2\.0$
4278 <!-- ~~~~~ New section ~~~~~ -->
4279 <sect3 renderas="sect4" id="handle-as-empty-document">
4280 <title>handle-as-empty-document</title>
4286 <term>Typical use:</term>
4288 <para>Mark URLs that should be replaced by empty documents <emphasis>if they get blocked</emphasis></para>
4293 <term>Effect:</term>
4296 This action alone doesn't do anything noticeable. It just marks URLs.
4297 If the <literal><link linkend="block">block</link></literal> action <emphasis>also applies</emphasis>,
4298 the presence or absence of this mark decides whether an HTML <quote>BLOCKED</quote>
4299 page, or an empty document will be sent to the client as a substitute for the blocked content.
4300 The <emphasis>empty</emphasis> document isn't literally empty, but actually contains a single space.
4307 <!-- Boolean, Parameterized, Multi-value -->
4309 <para>Boolean.</para>
4314 <term>Parameter:</term>
4326 Some browsers complain about syntax errors if JavaScript documents
4327 are blocked with <application>Privoxy's</application>
4328 default HTML page; this option can be used to silence them.
4329 And of course this action can also be used to eliminate the &my-app;
4330 BLOCKED message in frames.
4333 The content type for the empty document can be specified with
4334 <literal><link linkend="content-type-overwrite">content-type-overwrite{}</link></literal>,
4335 but usually this isn't necessary.
4341 <term>Example usage:</term>
4343 <screen># Block all documents on example.org that end with ".js",
4344 # but send an empty document instead of the usual HTML message.
4345 {+block{Blocked JavaScript} +handle-as-empty-document}
4354 <!-- ~~~~~ New section ~~~~~ -->
4355 <sect3 renderas="sect4" id="handle-as-image">
4356 <title>handle-as-image</title>
4360 <term>Typical use:</term>
4362 <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>
4367 <term>Effect:</term>
4370 This action alone doesn't do anything noticeable. It just marks URLs as images.
4371 If the <literal><link linkend="block">block</link></literal> action <emphasis>also applies</emphasis>,
4372 the presence or absence of this mark decides whether an HTML <quote>blocked</quote>
4373 page, or a replacement image (as determined by the <literal><link
4374 linkend="set-image-blocker">set-image-blocker</link></literal> action) will be sent to the
4375 client as a substitute for the blocked content.
4382 <!-- Boolean, Parameterized, Multi-value -->
4384 <para>Boolean.</para>
4389 <term>Parameter:</term>
4401 The below generic example section is actually part of <filename>default.action</filename>.
4402 It marks all URLs with well-known image file name extensions as images and should
4406 Users will probably only want to use the handle-as-image action in conjunction with
4407 <literal><link linkend="block">block</link></literal>, to block sources of banners, whose URLs don't
4408 reflect the file type, like in the second example section.
4411 Note that you cannot treat HTML pages as images in most cases. For instance, (in-line) ad
4412 frames require an HTML page to be sent, or they won't display properly.
4413 Forcing <literal>handle-as-image</literal> in this situation will not replace the
4414 ad frame with an image, but lead to error messages.
4420 <term>Example usage (sections):</term>
4422 <screen># Generic image extensions:
4425 /.*\.(gif|jpg|jpeg|png|bmp|ico)$
4427 # These don't look like images, but they're banners and should be
4428 # blocked as images:
4430 {+block{Nasty banners.} +handle-as-image}
4431 nasty-banner-server.example.com/junk.cgi\?output=trash
4439 <!-- ~~~~~ New section ~~~~~ -->
4440 <sect3 renderas="sect4" id="hide-accept-language">
4441 <title>hide-accept-language</title>
4447 <term>Typical use:</term>
4449 <para>Pretend to use different language settings.</para>
4454 <term>Effect:</term>
4457 Deletes or replaces the <quote>Accept-Language:</quote> HTTP header in client requests.
4464 <!-- Boolean, Parameterized, Multi-value -->
4466 <para>Parameterized.</para>
4471 <term>Parameter:</term>
4474 Keyword: <quote>block</quote>, or any user defined value.
4483 Faking the browser's language settings can be useful to make a
4484 foreign User-Agent set with
4485 <literal><link linkend="hide-user-agent">hide-user-agent</link></literal>
4489 However some sites with content in different languages check the
4490 <quote>Accept-Language:</quote> to decide which one to take by default.
4491 Sometimes it isn't possible to later switch to another language without
4492 changing the <quote>Accept-Language:</quote> header first.
4495 Therefore it's a good idea to either only change the
4496 <quote>Accept-Language:</quote> header to languages you understand,
4497 or to languages that aren't wide spread.
4500 Before setting the <quote>Accept-Language:</quote> header
4501 to a rare language, you should consider that it helps to
4502 make your requests unique and thus easier to trace.
4503 If you don't plan to change this header frequently,
4504 you should stick to a common language.
4510 <term>Example usage (section):</term>
4512 <screen># Pretend to use Canadian language settings.
4513 {+hide-accept-language{en-ca} \
4514 +hide-user-agent{Mozilla/5.0 (X11; U; OpenBSD i386; en-CA; rv:1.8.0.4) Gecko/20060628 Firefox/1.5.0.4} \
4523 <!-- ~~~~~ New section ~~~~~ -->
4524 <sect3 renderas="sect4" id="hide-content-disposition">
4525 <title>hide-content-disposition</title>
4531 <term>Typical use:</term>
4533 <para>Prevent download menus for content you prefer to view inside the browser.</para>
4538 <term>Effect:</term>
4541 Deletes or replaces the <quote>Content-Disposition:</quote> HTTP header set by some servers.
4548 <!-- Boolean, Parameterized, Multi-value -->
4550 <para>Parameterized.</para>
4555 <term>Parameter:</term>
4558 Keyword: <quote>block</quote>, or any user defined value.
4567 Some servers set the <quote>Content-Disposition:</quote> HTTP header for
4568 documents they assume you want to save locally before viewing them.
4569 The <quote>Content-Disposition:</quote> header contains the file name
4570 the browser is supposed to use by default.
4573 In most browsers that understand this header, it makes it impossible to
4574 <emphasis>just view</emphasis> the document, without downloading it first,
4575 even if it's just a simple text file or an image.
4578 Removing the <quote>Content-Disposition:</quote> header helps
4579 to prevent this annoyance, but some browsers additionally check the
4580 <quote>Content-Type:</quote> header, before they decide if they can
4581 display a document without saving it first. In these cases, you have
4582 to change this header as well, before the browser stops displaying
4586 It is also possible to change the server's file name suggestion
4587 to another one, but in most cases it isn't worth the time to set
4591 This action will probably be removed in the future,
4592 use server-header filters instead.
4598 <term>Example usage:</term>
4600 <screen># Disarm the download link in Sourceforge's patch tracker
4602 +content-type-overwrite{text/plain}\
4603 +hide-content-disposition{block} }
4604 .sourceforge.net/tracker/download\.php</screen>
4611 <!-- ~~~~~ New section ~~~~~ -->
4612 <sect3 renderas="sect4" id="hide-if-modified-since">
4613 <title>hide-if-modified-since</title>
4619 <term>Typical use:</term>
4621 <para>Prevent yet another way to track the user's steps between sessions.</para>
4626 <term>Effect:</term>
4629 Deletes the <quote>If-Modified-Since:</quote> HTTP client header or modifies its value.
4636 <!-- Boolean, Parameterized, Multi-value -->
4638 <para>Parameterized.</para>
4643 <term>Parameter:</term>
4646 Keyword: <quote>block</quote>, or a user defined value that specifies a range of hours.
4655 Removing this header is useful for filter testing, where you want to force a real
4656 reload instead of getting status code <quote>304</quote>, which would cause the
4657 browser to use a cached copy of the page.
4660 Instead of removing the header, <literal>hide-if-modified-since</literal> can
4661 also add or subtract a random amount of time to/from the header's value.
4662 You specify a range of minutes where the random factor should be chosen from and
4663 <application>Privoxy</application> does the rest. A negative value means
4664 subtracting, a positive value adding.
4667 Randomizing the value of the <quote>If-Modified-Since:</quote> makes
4668 it less likely that the server can use the time as a cookie replacement,
4669 but you will run into caching problems if the random range is too high.
4672 It is a good idea to only use a small negative value and let
4673 <literal><link linkend="overwrite-last-modified">overwrite-last-modified</link></literal>
4674 handle the greater changes.
4677 It is also recommended to use this action together with
4678 <literal><link linkend="crunch-if-none-match">crunch-if-none-match</link></literal>,
4679 otherwise it's more or less pointless.
4685 <term>Example usage (section):</term>
4687 <screen># Let the browser revalidate but make tracking based on the time less likely.
4688 {+hide-if-modified-since{-60} \
4689 +overwrite-last-modified{randomize} \
4690 +crunch-if-none-match}
4698 <!-- ~~~~~ New section ~~~~~ -->
4699 <sect3 renderas="sect4" id="hide-from-header">
4700 <title>hide-from-header</title>
4704 <term>Typical use:</term>
4706 <para>Keep your (old and ill) browser from telling web servers your email address</para>
4711 <term>Effect:</term>
4714 Deletes any existing <quote>From:</quote> HTTP header, or replaces it with the
4722 <!-- Boolean, Parameterized, Multi-value -->
4724 <para>Parameterized.</para>
4729 <term>Parameter:</term>
4732 Keyword: <quote>block</quote>, or any user defined value.
4741 The keyword <quote>block</quote> will completely remove the header
4742 (not to be confused with the <literal><link linkend="block">block</link></literal>
4746 Alternately, you can specify any value you prefer to be sent to the web
4747 server. If you do, it is a matter of fairness not to use any address that
4748 is actually used by a real person.
4751 This action is rarely needed, as modern web browsers don't send
4752 <quote>From:</quote> headers anymore.
4758 <term>Example usage:</term>
4760 <screen>+hide-from-header{block}</screen>
4762 <screen>+hide-from-header{spam-me-senseless@sittingduck.example.com}</screen>
4769 <!-- ~~~~~ New section ~~~~~ -->
4770 <sect3 renderas="sect4" id="hide-referrer">
4771 <title>hide-referrer</title>
4772 <anchor id="hide-referer">
4775 <term>Typical use:</term>
4777 <para>Conceal which link you followed to get to a particular site</para>
4782 <term>Effect:</term>
4785 Deletes the <quote>Referer:</quote> (sic) HTTP header from the client request,
4786 or replaces it with a forged one.
4793 <!-- Boolean, Parameterized, Multi-value -->
4795 <para>Parameterized.</para>
4800 <term>Parameter:</term>
4804 <para><quote>conditional-block</quote> to delete the header completely if the host has changed.</para>
4807 <para><quote>conditional-forge</quote> to forge the header if the host has changed.</para>
4810 <para><quote>block</quote> to delete the header unconditionally.</para>
4813 <para><quote>forge</quote> to pretend to be coming from the homepage of the server we are talking to.</para>
4816 <para>Any other string to set a user defined referrer.</para>
4826 <literal>conditional-block</literal> is the only parameter,
4827 that isn't easily detected in the server's log file. If it blocks the
4828 referrer, the request will look like the visitor used a bookmark or
4829 typed in the address directly.
4832 Leaving the referrer unmodified for requests on the same host
4833 allows the server owner to see the visitor's <quote>click path</quote>,
4834 but in most cases she could also get that information by comparing
4835 other parts of the log file: for example the User-Agent if it isn't
4836 a very common one, or the user's IP address if it doesn't change between
4840 Always blocking the referrer, or using a custom one, can lead to
4841 failures on servers that check the referrer before they answer any
4842 requests, in an attempt to prevent their content from being
4843 embedded or linked to elsewhere.
4846 Both <literal>conditional-block</literal> and <literal>forge</literal>
4847 will work with referrer checks, as long as content and valid referring page
4848 are on the same host. Most of the time that's the case.
4851 <literal>hide-referer</literal> is an alternate spelling of
4852 <literal>hide-referrer</literal> and the two can be can be freely
4853 substituted with each other. (<quote>referrer</quote> is the
4854 correct English spelling, however the HTTP specification has a bug - it
4855 requires it to be spelled as <quote>referer</quote>.)
4861 <term>Example usage:</term>
4863 <screen>+hide-referrer{forge}</screen>
4865 <screen>+hide-referrer{http://www.yahoo.com/}</screen>
4872 <!-- ~~~~~ New section ~~~~~ -->
4873 <sect3 renderas="sect4" id="hide-user-agent">
4874 <title>hide-user-agent</title>
4878 <term>Typical use:</term>
4880 <para>Try to conceal your type of browser and client operating system</para>
4885 <term>Effect:</term>
4888 Replaces the value of the <quote>User-Agent:</quote> HTTP header
4889 in client requests with the specified value.
4896 <!-- Boolean, Parameterized, Multi-value -->
4898 <para>Parameterized.</para>
4903 <term>Parameter:</term>
4906 Any user-defined string.
4916 This can lead to problems on web sites that depend on looking at this header in
4917 order to customize their content for different browsers (which, by the
4918 way, is <emphasis>NOT</emphasis> the right thing to do: good web sites
4919 work browser-independently).
4923 Using this action in multi-user setups or wherever different types of
4924 browsers will access the same <application>Privoxy</application> is
4925 <emphasis>not recommended</emphasis>. In single-user, single-browser
4926 setups, you might use it to delete your OS version information from
4927 the headers, because it is an invitation to exploit known bugs for your
4928 OS. It is also occasionally useful to forge this in order to access
4929 sites that won't let you in otherwise (though there may be a good
4930 reason in some cases).
4933 More information on known user-agent strings can be found at
4934 <ulink url="http://www.user-agents.org/">http://www.user-agents.org/</ulink>
4936 <ulink url="http://en.wikipedia.org/wiki/User_agent">http://en.wikipedia.org/wiki/User_agent</ulink>.
4942 <term>Example usage:</term>
4944 <screen>+hide-user-agent{Netscape 6.1 (X11; I; Linux 2.4.18 i686)}</screen>
4951 <!-- ~~~~~ New section ~~~~~ -->
4952 <sect3 renderas="sect4" id="limit-connect">
4953 <title>limit-connect</title>
4957 <term>Typical use:</term>
4959 <para>Prevent abuse of <application>Privoxy</application> as a TCP proxy relay or disable SSL for untrusted sites</para>
4964 <term>Effect:</term>
4967 Specifies to which ports HTTP CONNECT requests are allowable.
4974 <!-- Boolean, Parameterized, Multi-value -->
4976 <para>Parameterized.</para>
4981 <term>Parameter:</term>
4984 A comma-separated list of ports or port ranges (the latter using dashes, with the minimum
4985 defaulting to 0 and the maximum to 65K).
4994 By default, i.e. if no <literal>limit-connect</literal> action applies,
4995 <application>Privoxy</application> allows HTTP CONNECT requests to all
4996 ports. Use <literal>limit-connect</literal> if fine-grained control
4997 is desired for some or all destinations.
5000 The CONNECT methods exists in HTTP to allow access to secure websites
5001 (<quote>https://</quote> URLs) through proxies. It works very simply:
5002 the proxy connects to the server on the specified port, and then
5003 short-circuits its connections to the client and to the remote server.
5004 This means CONNECT-enabled proxies can be used as TCP relays very easily.
5007 <application>Privoxy</application> relays HTTPS traffic without seeing
5008 the decoded content. Websites can leverage this limitation to circumvent &my-app;'s
5009 filters. By specifying an invalid port range you can disable HTTPS entirely.
5015 <term>Example usages:</term>
5017 <!-- I had trouble getting the spacing to look right in my browser -->
5018 <!-- I probably have the wrong font setup, bollocks. -->
5019 <!-- Apparently the emphasis tag uses a proportional font no matter what -->
5020 <screen>+limit-connect{443} # Port 443 is OK.
5021 +limit-connect{80,443} # Ports 80 and 443 are OK.
5022 +limit-connect{-3, 7, 20-100, 500-} # Ports less than 3, 7, 20 to 100 and above 500 are OK.
5023 +limit-connect{-} # All ports are OK
5024 +limit-connect{,} # No HTTPS/SSL traffic is allowed</screen>
5031 <!-- ~~~~~ New section ~~~~~ -->
5032 <sect3 renderas="sect4" id="limit-cookie-lifetime">
5033 <title>limit-cookie-lifetime</title>
5037 <term>Typical use:</term>
5039 <para>Limit the lifetime of HTTP cookies to a couple of minutes or hours.</para>
5044 <term>Effect:</term>
5047 Overwrites the expires field in Set-Cookie server headers if it's above the specified limit.
5054 <!-- Boolean, Parameterized, Multi-value -->
5056 <para>Parameterized.</para>
5061 <term>Parameter:</term>
5064 The lifetime limit in minutes, or 0.
5073 This action reduces the lifetime of HTTP cookies coming from the
5074 server to the specified number of minutes, starting from the time
5075 the cookie passes Privoxy.
5078 Cookies with a lifetime below the limit are not modified.
5079 The lifetime of session cookies is set to the specified limit.
5082 The effect of this action depends on the server.
5085 In case of servers which refresh their cookies with each response
5086 (or at least frequently), the lifetime limit set by this action
5088 Thus, a session associated with the cookie continues to work with
5089 this action enabled, as long as a new request is made before the
5090 last limit set is reached.
5093 However, some servers send their cookies once, with a lifetime of several
5094 years (the year 2037 is a popular choice), and do not refresh them
5095 until a certain event in the future, for example the user logging out.
5096 In this case this action may limit the absolute lifetime of the session,
5097 even if requests are made frequently.
5100 If the parameter is <quote>0</quote>, this action behaves like
5101 <literal><link linkend="session-cookies-only">session-cookies-only</link></literal>.
5107 <term>Example usages:</term>
5109 <screen>+limit-cookie-lifetime{60}</screen>
5115 <!-- ~~~~~ New section ~~~~~ -->
5116 <sect3 renderas="sect4" id="prevent-compression">
5117 <title>prevent-compression</title>
5121 <term>Typical use:</term>
5124 Ensure that servers send the content uncompressed, so it can be
5125 passed through <literal><link linkend="filter">filter</link></literal>s.
5131 <term>Effect:</term>
5134 Removes the Accept-Encoding header which can be used to ask for compressed transfer.
5141 <!-- Boolean, Parameterized, Multi-value -->
5143 <para>Boolean.</para>
5148 <term>Parameter:</term>
5160 More and more websites send their content compressed by default, which
5161 is generally a good idea and saves bandwidth. But the <literal><link
5162 linkend="filter">filter</link></literal> and
5163 <literal><link linkend="deanimate-gifs">deanimate-gifs</link></literal>
5164 actions need access to the uncompressed data.
5167 When compiled with zlib support (available since &my-app; 3.0.7), content that should be
5168 filtered is decompressed on-the-fly and you don't have to worry about this action.
5169 If you are using an older &my-app; version, or one that hasn't been compiled with zlib
5170 support, this action can be used to convince the server to send the content uncompressed.
5173 Most text-based instances compress very well, the size is seldom decreased by less than 50%,
5174 for markup-heavy instances like news feeds saving more than 90% of the original size isn't
5178 Not using compression will therefore slow down the transfer, and you should only
5179 enable this action if you really need it. As of &my-app; 3.0.7 it's disabled in all
5180 predefined action settings.
5183 Note that some (rare) ill-configured sites don't handle requests for uncompressed
5184 documents correctly. Broken PHP applications tend to send an empty document body,
5185 some IIS versions only send the beginning of the content. If you enable
5186 <literal>prevent-compression</literal> per default, you might want to add
5187 exceptions for those sites. See the example for how to do that.
5193 <term>Example usage (sections):</term>
5196 # Selectively turn off compression, and enable a filter
5198 { +filter{tiny-textforms} +prevent-compression }
5199 # Match only these sites
5204 # Or instead, we could set a universal default:
5206 { +prevent-compression }
5209 # Then maybe make exceptions for broken sites:
5211 { -prevent-compression }
5212 .compusa.com/</screen>
5220 <!-- ~~~~~ New section ~~~~~ -->
5221 <sect3 renderas="sect4" id="overwrite-last-modified">
5222 <title>overwrite-last-modified</title>
5228 <term>Typical use:</term>
5230 <para>Prevent yet another way to track the user's steps between sessions.</para>
5235 <term>Effect:</term>
5238 Deletes the <quote>Last-Modified:</quote> HTTP server header or modifies its value.
5245 <!-- Boolean, Parameterized, Multi-value -->
5247 <para>Parameterized.</para>
5252 <term>Parameter:</term>
5255 One of the keywords: <quote>block</quote>, <quote>reset-to-request-time</quote>
5256 and <quote>randomize</quote>
5265 Removing the <quote>Last-Modified:</quote> header is useful for filter
5266 testing, where you want to force a real reload instead of getting status
5267 code <quote>304</quote>, which would cause the browser to reuse the old
5268 version of the page.
5271 The <quote>randomize</quote> option overwrites the value of the
5272 <quote>Last-Modified:</quote> header with a randomly chosen time
5273 between the original value and the current time. In theory the server
5274 could send each document with a different <quote>Last-Modified:</quote>
5275 header to track visits without using cookies. <quote>Randomize</quote>
5276 makes it impossible and the browser can still revalidate cached documents.
5279 <quote>reset-to-request-time</quote> overwrites the value of the
5280 <quote>Last-Modified:</quote> header with the current time. You could use
5281 this option together with
5282 <literal><link linkend="hide-if-modified-since">hide-if-modified-since</link></literal>
5283 to further customize your random range.
5286 The preferred parameter here is <quote>randomize</quote>. It is safe
5287 to use, as long as the time settings are more or less correct.
5288 If the server sets the <quote>Last-Modified:</quote> header to the time
5289 of the request, the random range becomes zero and the value stays the same.
5290 Therefore you should later randomize it a second time with
5291 <literal><link linkend="hide-if-modified-since">hided-if-modified-since</link></literal>,
5295 It is also recommended to use this action together with
5296 <literal><link linkend="crunch-if-none-match">crunch-if-none-match</link></literal>.
5302 <term>Example usage:</term>
5304 <screen># Let the browser revalidate without being tracked across sessions
5305 { +hide-if-modified-since{-60} \
5306 +overwrite-last-modified{randomize} \
5307 +crunch-if-none-match}
5315 <!-- ~~~~~ New section ~~~~~ -->
5316 <sect3 renderas="sect4" id="redirect">
5317 <title>redirect</title>
5323 <term>Typical use:</term>
5326 Redirect requests to other sites.
5332 <term>Effect:</term>
5335 Convinces the browser that the requested document has been moved
5336 to another location and the browser should get it from there.
5343 <!-- Boolean, Parameterized, Multi-value -->
5345 <para>Parameterized</para>
5350 <term>Parameter:</term>
5353 An absolute URL or a single pcrs command.
5362 Requests to which this action applies are answered with a
5363 HTTP redirect to URLs of your choosing. The new URL is
5364 either provided as parameter, or derived by applying a
5365 single pcrs command to the original URL.
5368 The syntax for pcrs commands is documented in the
5369 <link linkend="filter-file">filter file</link> section.
5372 Requests can't be blocked and redirected at the same time,
5373 applying this action together with
5374 <literal><link linkend="block">block</link></literal>
5375 is a configuration error. Currently the request is blocked
5376 and an error message logged, the behavior may change in the
5377 future and result in Privoxy rejecting the action file.
5380 This action can be combined with
5381 <literal><link linkend="fast-redirects">fast-redirects{check-decoded-url}</link></literal>
5382 to redirect to a decoded version of a rewritten URL.
5385 Use this action carefully, make sure not to create redirection loops
5386 and be aware that using your own redirects might make it
5387 possible to fingerprint your requests.
5390 In case of problems with your redirects, or simply to watch
5391 them working, enable <link linkend="DEBUG">debug 128</link>.
5397 <term>Example usages:</term>
5399 <screen># Replace example.com's style sheet with another one
5400 { +redirect{http://localhost/css-replacements/example.com.css} }
5401 example.com/stylesheet\.css
5403 # Create a short, easy to remember nickname for a favorite site
5404 # (relies on the browser to accept and forward invalid URLs to &my-app;)
5405 { +redirect{https://www.privoxy.org/user-manual/actions-file.html} }
5408 # Always use the expanded view for Undeadly.org articles
5409 # (Note the $ at the end of the URL pattern to make sure
5410 # the request for the rewritten URL isn't redirected as well)
5411 {+redirect{s@$@&mode=expanded@}}
5412 undeadly.org/cgi\?action=article&sid=\d*$
5414 # Redirect Google search requests to MSN
5415 {+redirect{s@^http://[^/]*/search\?q=([^&]*).*@http://search.msn.com/results.aspx?q=$1@}}
5418 # Redirect MSN search requests to Yahoo
5419 {+redirect{s@^http://[^/]*/results\.aspx\?q=([^&]*).*@http://search.yahoo.com/search?p=$1@}}
5420 search.msn.com//results\.aspx\?q=
5422 # Redirect http://example.com/&bla=fasel&toChange=foo (and any other value but "bar")
5423 # to http://example.com/&bla=fasel&toChange=bar
5425 # The URL pattern makes sure that the following request isn't redirected again.
5426 {+redirect{s@toChange=[^&]+@toChange=bar@}}
5427 example.com/.*toChange=(?!bar)
5429 # Add a shortcut to look up illumos bugs
5430 {+redirect{s@^http://i([0-9]+)/.*@https://www.illumos.org/issues/$1@}}
5431 # Redirected URL = http://i4974/
5432 # Redirect Destination = https://www.illumos.org/issues/4974
5433 i[0-9][0-9][0-9][0-9]*/
5435 # Redirect remote requests for this manual
5436 # to the local version delivered by Privoxy
5437 {+redirect{s@^http://www@http://config@}}
5438 www.privoxy.org/user-manual/</screen>
5446 <!-- ~~~~~ New section ~~~~~ -->
5447 <sect3 renderas="sect4" id="server-header-filter">
5448 <title>server-header-filter</title>
5452 <term>Typical use:</term>
5455 Rewrite or remove single server headers.
5461 <term>Effect:</term>
5464 All server headers to which this action applies are filtered on-the-fly
5465 through the specified regular expression based substitutions.
5472 <!-- boolean, parameterized, Multi-value -->
5474 <para>Multi-value.</para>
5479 <term>Parameter:</term>
5482 The name of a server-header filter, as defined in one of the
5483 <link linkend="filter-file">filter files</link>.
5492 Server-header filters are applied to each header on its own, not to
5493 all at once. This makes it easier to diagnose problems, but on the downside
5494 you can't write filters that only change header x if header y's value is z.
5495 You can do that by using tags though.
5498 Server-header filters are executed after the other header actions have finished
5499 and use their output as input.
5502 Please refer to the <link linkend="filter-file">filter file chapter</link>
5503 to learn which server-header filters are available by default, and how to
5510 <term>Example usage (section):</term>
5513 {+server-header-filter{html-to-xml}}
5514 example.org/xml-instance-that-is-delivered-as-html
5516 {+server-header-filter{xml-to-html}}
5517 example.org/instance-that-is-delivered-as-xml-but-is-not
5526 <!-- ~~~~~ New section ~~~~~ -->
5527 <sect3 renderas="sect4" id="server-header-tagger">
5528 <title>server-header-tagger</title>
5532 <term>Typical use:</term>
5535 Enable or disable filters based on the Content-Type header.
5541 <term>Effect:</term>
5544 Server headers to which this action applies are filtered on-the-fly through
5545 the specified regular expression based substitutions, the result is used as
5553 <!-- boolean, parameterized, Multi-value -->
5555 <para>Multi-value.</para>
5560 <term>Parameter:</term>
5563 The name of a server-header tagger, as defined in one of the
5564 <link linkend="filter-file">filter files</link>.
5573 Server-header taggers are applied to each header on its own,
5574 and as the header isn't modified, each tagger <quote>sees</quote>
5578 Server-header taggers are executed before all other header actions
5579 that modify server headers. Their tags can be used to control
5580 all of the other server-header actions, the content filters
5581 and the crunch actions (<link linkend="redirect">redirect</link>
5582 and <link linkend="block">block</link>).
5585 Obviously crunching based on tags created by server-header taggers
5586 doesn't prevent the request from showing up in the server's log file.
5593 <term>Example usage (section):</term>
5596 # Tag every request with the content type declared by the server
5597 {+server-header-tagger{content-type}}
5600 # If the response has a tag starting with 'image/' enable an external
5601 # filter that only applies to images.
5603 # Note that the filter is not available by default, it's just a
5604 # <literal><link linkend="external-filter-syntax">silly example</link></literal>.
5605 {+external-filter{rotate-image} +force-text-mode}
5615 <!-- ~~~~~ New section ~~~~~ -->
5616 <sect3 renderas="sect4" id="session-cookies-only">
5617 <title>session-cookies-only</title>
5621 <term>Typical use:</term>
5624 Allow only temporary <quote>session</quote> cookies (for the current
5625 browser session <emphasis>only</emphasis>).
5631 <term>Effect:</term>
5634 Deletes the <quote>expires</quote> field from <quote>Set-Cookie:</quote>
5635 server headers. Most browsers will not store such cookies permanently and
5636 forget them in between sessions.
5643 <!-- Boolean, Parameterized, Multi-value -->
5645 <para>Boolean.</para>
5650 <term>Parameter:</term>
5662 This is less strict than <literal><link linkend="crunch-incoming-cookies">crunch-incoming-cookies</link></literal> /
5663 <literal><link linkend="crunch-outgoing-cookies">crunch-outgoing-cookies</link></literal> and allows you to browse
5664 websites that insist or rely on setting cookies, without compromising your privacy too badly.
5667 Most browsers will not permanently store cookies that have been processed by
5668 <literal>session-cookies-only</literal> and will forget about them between sessions.
5669 This makes profiling cookies useless, but won't break sites which require cookies so
5670 that you can log in for transactions. This is generally turned on for all
5671 sites, and is the recommended setting.
5674 It makes <emphasis>no sense at all</emphasis> to use <literal>session-cookies-only</literal>
5675 together with <literal><link linkend="crunch-incoming-cookies">crunch-incoming-cookies</link></literal> or
5676 <literal><link linkend="crunch-outgoing-cookies">crunch-outgoing-cookies</link></literal>. If you do, cookies
5677 will be plainly killed.
5680 Note that it is up to the browser how it handles such cookies without an <quote>expires</quote>
5681 field. If you use an exotic browser, you might want to try it out to be sure.
5684 This setting also has no effect on cookies that may have been stored
5685 previously by the browser before starting <application>Privoxy</application>.
5686 These would have to be removed manually.
5689 <application>Privoxy</application> also uses
5690 the <link linkend="filter-content-cookies">content-cookies filter</link>
5691 to block some types of cookies. Content cookies are not effected by
5692 <literal>session-cookies-only</literal>.
5698 <term>Example usage:</term>
5700 <screen>+session-cookies-only</screen>
5707 <!-- ~~~~~ New section ~~~~~ -->
5708 <sect3 renderas="sect4" id="set-image-blocker">
5709 <title>set-image-blocker</title>
5713 <term>Typical use:</term>
5715 <para>Choose the replacement for blocked images</para>
5720 <term>Effect:</term>
5723 This action alone doesn't do anything noticeable. If <emphasis>both</emphasis>
5724 <literal><link linkend="block">block</link></literal> <emphasis>and</emphasis> <literal><link
5725 linkend="handle-as-image">handle-as-image</link></literal> <emphasis>also</emphasis>
5726 apply, i.e. if the request is to be blocked as an image,
5727 <emphasis>then</emphasis> the parameter of this action decides what will be
5728 sent as a replacement.
5735 <!-- Boolean, Parameterized, Multi-value -->
5737 <para>Parameterized.</para>
5742 <term>Parameter:</term>
5747 <quote>pattern</quote> to send a built-in checkerboard pattern image. The image is visually
5748 decent, scales very well, and makes it obvious where banners were busted.
5753 <quote>blank</quote> to send a built-in transparent image. This makes banners disappear
5754 completely, but makes it hard to detect where <application>Privoxy</application> has blocked
5755 images on a given page and complicates troubleshooting if <application>Privoxy</application>
5756 has blocked innocent images, like navigation icons.
5761 <quote><replaceable class="parameter">target-url</replaceable></quote> to
5762 send a redirect to <replaceable class="parameter">target-url</replaceable>. You can redirect
5763 to any image anywhere, even in your local filesystem via <quote>file:///</quote> URL.
5764 (But note that not all browsers support redirecting to a local file system).
5767 A good application of redirects is to use special <application>Privoxy</application>-built-in
5768 URLs, which send the built-in images, as <replaceable class="parameter">target-url</replaceable>.
5769 This has the same visual effect as specifying <quote>blank</quote> or <quote>pattern</quote> in
5770 the first place, but enables your browser to cache the replacement image, instead of requesting
5771 it over and over again.
5782 The URLs for the built-in images are <quote>http://config.privoxy.org/send-banner?type=<replaceable
5783 class="parameter">type</replaceable></quote>, where <replaceable class="parameter">type</replaceable> is
5784 either <quote>blank</quote> or <quote>pattern</quote>.
5787 There is a third (advanced) type, called <quote>auto</quote>. It is <emphasis>NOT</emphasis> to be
5788 used in <literal>set-image-blocker</literal>, but meant for use from <link linkend="filter-file">filters</link>.
5789 Auto will select the type of image that would have applied to the referring page, had it been an image.
5795 <term>Example usage:</term>
5800 <screen>+set-image-blocker{pattern}</screen>
5802 Redirect to the BSD daemon:
5804 <screen>+set-image-blocker{http://www.freebsd.org/gifs/dae_up3.gif}</screen>
5806 Redirect to the built-in pattern for better caching:
5808 <screen>+set-image-blocker{http://config.privoxy.org/send-banner?type=pattern}</screen>
5815 <!-- ~~~~~ New section ~~~~~ -->
5816 <sect3 id="summary">
5817 <title>Summary</title>
5819 Note that many of these actions have the potential to cause a page to
5820 misbehave, possibly even not to display at all. There are many ways
5821 a site designer may choose to design his site, and what HTTP header
5822 content, and other criteria, he may depend on. There is no way to have hard
5823 and fast rules for all sites. See the <link
5824 linkend="ACTIONSANAT">Appendix</link> for a brief example on troubleshooting
5830 <!-- ~~~~~ New section ~~~~~ -->
5831 <sect2 id="aliases">
5832 <title>Aliases</title>
5834 Custom <quote>actions</quote>, known to <application>Privoxy</application>
5835 as <quote>aliases</quote>, can be defined by combining other actions.
5836 These can in turn be invoked just like the built-in actions.
5837 Currently, an alias name can contain any character except space, tab,
5839 <quote>{</quote> and <quote>}</quote>, but we <emphasis>strongly
5840 recommend</emphasis> that you only use <quote>a</quote> to <quote>z</quote>,
5841 <quote>0</quote> to <quote>9</quote>, <quote>+</quote>, and <quote>-</quote>.
5842 Alias names are not case sensitive, and are not required to start with a
5843 <quote>+</quote> or <quote>-</quote> sign, since they are merely textually
5847 Aliases can be used throughout the actions file, but they <emphasis>must be
5848 defined in a special section at the top of the file!</emphasis>
5849 And there can only be one such section per actions file. Each actions file may
5850 have its own alias section, and the aliases defined in it are only visible
5854 There are two main reasons to use aliases: One is to save typing for frequently
5855 used combinations of actions, the other one is a gain in flexibility: If you
5856 decide once how you want to handle shops by defining an alias called
5857 <quote>shop</quote>, you can later change your policy on shops in
5858 <emphasis>one</emphasis> place, and your changes will take effect everywhere
5859 in the actions file where the <quote>shop</quote> alias is used. Calling aliases
5860 by their purpose also makes your actions files more readable.
5863 Currently, there is one big drawback to using aliases, though:
5864 <application>Privoxy</application>'s built-in web-based action file
5865 editor honors aliases when reading the actions files, but it expands
5866 them before writing. So the effects of your aliases are of course preserved,
5867 but the aliases themselves are lost when you edit sections that use aliases
5872 Now let's define some aliases...
5876 # Useful custom aliases we can use later.
5878 # Note the (required!) section header line and that this section
5879 # must be at the top of the actions file!
5883 # These aliases just save typing later:
5884 # (Note that some already use other aliases!)
5886 +crunch-all-cookies = +<link linkend="CRUNCH-INCOMING-COOKIES">crunch-incoming-cookies</link> +<link linkend="CRUNCH-OUTGOING-COOKIES">crunch-outgoing-cookies</link>
5887 -crunch-all-cookies = -<link linkend="CRUNCH-INCOMING-COOKIES">crunch-incoming-cookies</link> -<link linkend="CRUNCH-OUTGOING-COOKIES">crunch-outgoing-cookies</link>
5888 +block-as-image = +block{Blocked image.} +handle-as-image
5889 allow-all-cookies = -crunch-all-cookies -<link linkend="SESSION-COOKIES-ONLY">session-cookies-only</link> -<link linkend="FILTER-CONTENT-COOKIES">filter{content-cookies}</link>
5891 # These aliases define combinations of actions
5892 # that are useful for certain types of sites:
5894 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>
5896 shop = -crunch-all-cookies -<link linkend="FILTER-ALL-POPUPS">filter{all-popups}</link>
5898 # Short names for other aliases, for really lazy people ;-)
5900 c0 = +crunch-all-cookies
5901 c1 = -crunch-all-cookies</screen>
5904 ...and put them to use. These sections would appear in the lower part of an
5905 actions file and define exceptions to the default actions (as specified further
5906 up for the <quote>/</quote> pattern):
5910 # These sites are either very complex or very keen on
5911 # user data and require minimal interference to work:
5914 .office.microsoft.com
5915 .windowsupdate.microsoft.com
5916 # Gmail is really mail.google.com, not gmail.com
5920 # Allow cookies (for setting and retrieving your customer data)
5924 .worldpay.com # for quietpc.com
5927 # These shops require pop-ups:
5929 {-filter{all-popups} -filter{unsolicited-popups}}
5931 .overclockers.co.uk</screen>
5934 Aliases like <quote>shop</quote> and <quote>fragile</quote> are typically used for
5935 <quote>problem</quote> sites that require more than one action to be disabled
5936 in order to function properly.
5942 <!-- ~~~~~ New section ~~~~~ -->
5943 <sect2 id="act-examples">
5944 <title>Actions Files Tutorial</title>
5946 The above chapters have shown <link linkend="actions-file">which actions files
5947 there are and how they are organized</link>, how actions are <link
5948 linkend="actions">specified</link> and <link linkend="actions-apply">applied
5949 to URLs</link>, how <link linkend="af-patterns">patterns</link> work, and how to
5950 define and use <link linkend="aliases">aliases</link>. Now, let's look at an
5951 example <filename>match-all.action</filename>, <filename>default.action</filename>
5952 and <filename>user.action</filename> file and see how all these pieces come together:
5955 <sect3 id="match-all">
5956 <title>match-all.action</title>
5958 Remember <emphasis>all actions are disabled when matching starts</emphasis>,
5959 so we have to explicitly enable the ones we want.
5963 While the <filename>match-all.action</filename> file only contains a
5964 single section, it is probably the most important one. It has only one
5965 pattern, <quote><literal>/</literal></quote>, but this pattern
5966 <link linkend="af-patterns">matches all URLs</link>. Therefore, the set of
5967 actions used in this <quote>default</quote> section <emphasis>will
5968 be applied to all requests as a start</emphasis>. It can be partly or
5969 wholly overridden by other actions files like <filename>default.action</filename>
5970 and <filename>user.action</filename>, but it will still be largely responsible
5971 for your overall browsing experience.
5975 Again, at the start of matching, all actions are disabled, so there is
5976 no need to disable any actions here. (Remember: a <quote>+</quote>
5977 preceding the action name enables the action, a <quote>-</quote> disables!).
5978 Also note how this long line has been made more readable by splitting it into
5979 multiple lines with line continuation.
5984 +<link linkend="CHANGE-X-FORWARDED-FOR">change-x-forwarded-for{block}</link> \
5985 +<link linkend="HIDE-FROM-HEADER">hide-from-header{block}</link> \
5986 +<link linkend="SET-IMAGE-BLOCKER">set-image-blocker{pattern}</link> \
5992 The default behavior is now set.
5996 <sect3 id="default-action">
5997 <title>default.action</title>
6000 If you aren't a developer, there's no need for you to edit the
6001 <filename>default.action</filename> file. It is maintained by
6002 the &my-app; developers and if you disagree with some of the
6003 sections, you should overrule them in your <filename>user.action</filename>.
6007 Understanding the <filename>default.action</filename> file can
6008 help you with your <filename>user.action</filename>, though.
6012 The first section in this file is a special section for internal use
6013 that prevents older &my-app; versions from reading the file:
6017 ##########################################################################
6018 # Settings -- Don't change! For internal Privoxy use ONLY.
6019 ##########################################################################
6021 for-privoxy-version=3.0.11</screen>
6024 After that comes the (optional) alias section. We'll use the example
6025 section from the above <link linkend="aliases">chapter on aliases</link>,
6026 that also explains why and how aliases are used:
6030 ##########################################################################
6032 ##########################################################################
6035 # These aliases just save typing later:
6036 # (Note that some already use other aliases!)
6038 +crunch-all-cookies = +<link linkend="CRUNCH-INCOMING-COOKIES">crunch-incoming-cookies</link> +<link linkend="CRUNCH-OUTGOING-COOKIES">crunch-outgoing-cookies</link>
6039 -crunch-all-cookies = -<link linkend="CRUNCH-INCOMING-COOKIES">crunch-incoming-cookies</link> -<link linkend="CRUNCH-OUTGOING-COOKIES">crunch-outgoing-cookies</link>
6040 +block-as-image = +block{Blocked image.} +handle-as-image
6041 mercy-for-cookies = -crunch-all-cookies -<link linkend="SESSION-COOKIES-ONLY">session-cookies-only</link> -<link linkend="FILTER-CONTENT-COOKIES">filter{content-cookies}</link>
6043 # These aliases define combinations of actions
6044 # that are useful for certain types of sites:
6046 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>
6047 shop = -crunch-all-cookies -<link linkend="FILTER-ALL-POPUPS">filter{all-popups}</link></screen>
6050 The first of our specialized sections is concerned with <quote>fragile</quote>
6051 sites, i.e. sites that require minimum interference, because they are either
6052 very complex or very keen on tracking you (and have mechanisms in place that
6053 make them unusable for people who avoid being tracked). We will use
6054 our pre-defined <literal>fragile</literal> alias instead of stating the list
6055 of actions explicitly:
6059 ##########################################################################
6060 # Exceptions for sites that'll break under the default action set:
6061 ##########################################################################
6063 # "Fragile" Use a minimum set of actions for these sites (see alias above):
6066 .office.microsoft.com # surprise, surprise!
6067 .windowsupdate.microsoft.com
6068 mail.google.com</screen>
6071 Shopping sites are not as fragile, but they typically
6072 require cookies to log in, and pop-up windows for shopping
6073 carts or item details. Again, we'll use a pre-defined alias:
6081 .worldpay.com # for quietpc.com
6083 .scan.co.uk</screen>
6086 The <literal><link linkend="FAST-REDIRECTS">fast-redirects</link></literal>
6087 action, which may have been enabled in <filename>match-all.action</filename>,
6088 breaks some sites. So disable it for popular sites where we know it misbehaves:
6092 { -<link linkend="FAST-REDIRECTS">fast-redirects</link> }
6096 .altavista.com/.*(like|url|link):http
6097 .altavista.com/trans.*urltext=http
6098 .nytimes.com</screen>
6101 It is important that <application>Privoxy</application> knows which
6102 URLs belong to images, so that <emphasis>if</emphasis> they are to
6103 be blocked, a substitute image can be sent, rather than an HTML page.
6104 Contacting the remote site to find out is not an option, since it
6105 would destroy the loading time advantage of banner blocking, and it
6106 would feed the advertisers information about you. We can mark any
6107 URL as an image with the <literal><link
6108 linkend="handle-as-image">handle-as-image</link></literal> action,
6109 and marking all URLs that end in a known image file extension is a
6114 ##########################################################################
6116 ##########################################################################
6118 # Define which file types will be treated as images, in case they get
6119 # blocked further down this file:
6121 { +<link linkend="HANDLE-AS-IMAGE">handle-as-image</link> }
6122 /.*\.(gif|jpe?g|png|bmp|ico)$</screen>
6125 And then there are known banner sources. They often use scripts to
6126 generate the banners, so it won't be visible from the URL that the
6127 request is for an image. Hence we block them <emphasis>and</emphasis>
6128 mark them as images in one go, with the help of our
6129 <literal>+block-as-image</literal> alias defined above. (We could of
6130 course just as well use <literal>+<link linkend="block">block</link>
6131 +<link linkend="handle-as-image">handle-as-image</link></literal> here.)
6132 Remember that the type of the replacement image is chosen by the
6133 <literal><link linkend="set-image-blocker">set-image-blocker</link></literal>
6134 action. Since all URLs have matched the default section with its
6135 <literal>+<link linkend="set-image-blocker">set-image-blocker</link>{pattern}</literal>
6136 action before, it still applies and needn't be repeated:
6140 # Known ad generators:
6145 .ad.*.doubleclick.net
6146 .a.yimg.com/(?:(?!/i/).)*$
6147 .a[0-9].yimg.com/(?:(?!/i/).)*$
6152 One of the most important jobs of <application>Privoxy</application>
6153 is to block banners. Many of these can be <quote>blocked</quote>
6154 by the <literal><link linkend="filter">filter</link>{banners-by-size}</literal>
6155 action, which we enabled above, and which deletes the references to banner
6156 images from the pages while they are loaded, so the browser doesn't request
6157 them anymore, and hence they don't need to be blocked here. But this naturally
6158 doesn't catch all banners, and some people choose not to use filters, so we
6159 need a comprehensive list of patterns for banner URLs here, and apply the
6160 <literal><link linkend="block">block</link></literal> action to them.
6163 First comes many generic patterns, which do most of the work, by
6164 matching typical domain and path name components of banners. Then comes
6165 a list of individual patterns for specific sites, which is omitted here
6166 to keep the example short:
6170 ##########################################################################
6171 # Block these fine banners:
6172 ##########################################################################
6173 { <link linkend="BLOCK">+block{Banner ads.}</link> }
6181 /.*count(er)?\.(pl|cgi|exe|dll|asp|php[34]?)
6182 /(?:.*/)?(publicite|werbung|rekla(ma|me|am)|annonse|maino(kset|nta|s)?)/
6184 # Site-specific patterns (abbreviated):
6186 .hitbox.com</screen>
6189 It's quite remarkable how many advertisers actually call their banner
6190 servers ads.<replaceable>company</replaceable>.com, or call the directory
6191 in which the banners are stored literally <quote>banners</quote>. So the above
6192 generic patterns are surprisingly effective.
6195 But being very generic, they necessarily also catch URLs that we don't want
6196 to block. The pattern <literal>.*ads.</literal> e.g. catches
6197 <quote>nasty-<emphasis>ads</emphasis>.nasty-corp.com</quote> as intended,
6198 but also <quote>downlo<emphasis>ads</emphasis>.sourcefroge.net</quote> or
6199 <quote><emphasis>ads</emphasis>l.some-provider.net.</quote> So here come some
6200 well-known exceptions to the <literal>+<link linkend="BLOCK">block</link></literal>
6204 Note that these are exceptions to exceptions from the default! Consider the URL
6205 <quote>downloads.sourcefroge.net</quote>: Initially, all actions are deactivated,
6206 so it wouldn't get blocked. Then comes the defaults section, which matches the
6207 URL, but just deactivates the <literal><link linkend="BLOCK">block</link></literal>
6208 action once again. Then it matches <literal>.*ads.</literal>, an exception to the
6209 general non-blocking policy, and suddenly
6210 <literal><link linkend="BLOCK">+block</link></literal> applies. And now, it'll match
6211 <literal>.*loads.</literal>, where <literal><link linkend="BLOCK">-block</link></literal>
6212 applies, so (unless it matches <emphasis>again</emphasis> further down) it ends up
6213 with no <literal><link linkend="BLOCK">block</link></literal> action applying.
6217 ##########################################################################
6218 # Save some innocent victims of the above generic block patterns:
6219 ##########################################################################
6223 { -<link linkend="BLOCK">block</link> }
6224 adv[io]*. # (for advogato.org and advice.*)
6225 adsl. # (has nothing to do with ads)
6226 adobe. # (has nothing to do with ads either)
6227 ad[ud]*. # (adult.* and add.*)
6228 .edu # (universities don't host banners (yet!))
6229 .*loads. # (downloads, uploads etc)
6237 www.globalintersec.com/adv # (adv = advanced)
6238 www.ugu.com/sui/ugu/adv</screen>
6241 Filtering source code can have nasty side effects,
6242 so make an exception for our friends at sourceforge.net,
6243 and all paths with <quote>cvs</quote> in them. Note that
6244 <literal>-<link linkend="FILTER">filter</link></literal>
6245 disables <emphasis>all</emphasis> filters in one fell swoop!
6249 # Don't filter code!
6251 { -<link linkend="FILTER">filter</link> }
6256 .sourceforge.net</screen>
6259 The actual <filename>default.action</filename> is of course much more
6260 comprehensive, but we hope this example made clear how it works.
6265 <sect3 id="user-action"><title>user.action</title>
6268 So far we are painting with a broad brush by setting general policies,
6269 which would be a reasonable starting point for many people. Now,
6270 you might want to be more specific and have customized rules that
6271 are more suitable to your personal habits and preferences. These would
6272 be for narrowly defined situations like your ISP or your bank, and should
6273 be placed in <filename>user.action</filename>, which is parsed after all other
6274 actions files and hence has the last word, over-riding any previously
6275 defined actions. <filename>user.action</filename> is also a
6276 <emphasis>safe</emphasis> place for your personal settings, since
6277 <filename>default.action</filename> is actively maintained by the
6278 <application>Privoxy</application> developers and you'll probably want
6279 to install updated versions from time to time.
6283 So let's look at a few examples of things that one might typically do in
6284 <filename>user.action</filename>:
6288 <!-- brief sample user.action here -->
6291 # My user.action file. <fred@example.com></screen>
6294 As <link linkend="aliases">aliases</link> are local to the actions
6295 file that they are defined in, you can't use the ones from
6296 <filename>default.action</filename>, unless you repeat them here:
6300 # Aliases are local to the file they are defined in.
6301 # (Re-)define aliases for this file:
6305 # These aliases just save typing later, and the alias names should
6306 # be self explanatory.
6308 +crunch-all-cookies = +crunch-incoming-cookies +crunch-outgoing-cookies
6309 -crunch-all-cookies = -crunch-incoming-cookies -crunch-outgoing-cookies
6310 allow-all-cookies = -crunch-all-cookies -session-cookies-only
6311 allow-popups = -filter{all-popups}
6312 +block-as-image = +block{Blocked as image.} +handle-as-image
6313 -block-as-image = -block
6315 # These aliases define combinations of actions that are useful for
6316 # certain types of sites:
6318 fragile = -block -crunch-all-cookies -filter -fast-redirects -hide-referrer
6319 shop = -crunch-all-cookies allow-popups
6321 # Allow ads for selected useful free sites:
6323 allow-ads = -block -filter{banners-by-size} -filter{banners-by-link}
6325 # Alias for specific file types that are text, but might have conflicting
6326 # MIME types. We want the browser to force these to be text documents.
6327 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>
6330 Say you have accounts on some sites that you visit regularly, and
6331 you don't want to have to log in manually each time. So you'd like
6332 to allow persistent cookies for these sites. The
6333 <literal>allow-all-cookies</literal> alias defined above does exactly
6334 that, i.e. it disables crunching of cookies in any direction, and the
6335 processing of cookies to make them only temporary.
6339 { allow-all-cookies }
6343 .redhat.com</screen>
6346 Your bank is allergic to some filter, but you don't know which, so you disable them all:
6350 { -<link linkend="FILTER">filter</link> }
6351 .your-home-banking-site.com</screen>
6354 Some file types you may not want to filter for various reasons:
6358 # Technical documentation is likely to contain strings that might
6359 # erroneously get altered by the JavaScript-oriented filters:
6364 # And this stupid host sends streaming video with a wrong MIME type,
6365 # so that Privoxy thinks it is getting HTML and starts filtering:
6367 stupid-server.example.com/</screen>
6370 Example of a simple <link linkend="BLOCK">block</link> action. Say you've
6371 seen an ad on your favourite page on example.com that you want to get rid of.
6372 You have right-clicked the image, selected <quote>copy image location</quote>
6373 and pasted the URL below while removing the leading http://, into a
6374 <literal>{ +block{} }</literal> section. Note that <literal>{ +handle-as-image
6375 }</literal> need not be specified, since all URLs ending in
6376 <literal>.gif</literal> will be tagged as images by the general rules as set
6377 in default.action anyway:
6381 { +<link linkend="BLOCK">block</link>{Nasty ads.} }
6382 www.example.com/nasty-ads/sponsor\.gif
6383 another.example.net/more/junk/here/</screen>
6386 The URLs of dynamically generated banners, especially from large banner
6387 farms, often don't use the well-known image file name extensions, which
6388 makes it impossible for <application>Privoxy</application> to guess
6389 the file type just by looking at the URL.
6390 You can use the <literal>+block-as-image</literal> alias defined above for
6392 Note that objects which match this rule but then turn out NOT to be an
6393 image are typically rendered as a <quote>broken image</quote> icon by the
6394 browser. Use cautiously.
6402 ar.atwola.com/</screen>
6405 Now you noticed that the default configuration breaks Forbes Magazine,
6406 but you were too lazy to find out which action is the culprit, and you
6407 were again too lazy to give <link linkend="contact">feedback</link>, so
6408 you just used the <literal>fragile</literal> alias on the site, and
6409 -- <emphasis>whoa!</emphasis> -- it worked. The <literal>fragile</literal>
6410 aliases disables those actions that are most likely to break a site. Also,
6411 good for testing purposes to see if it is <application>Privoxy</application>
6412 that is causing the problem or not. We later find other regular sites
6413 that misbehave, and add those to our personalized list of troublemakers:
6420 .mybank.com</screen>
6423 You like the <quote>fun</quote> text replacements in <filename>default.filter</filename>,
6424 but it is disabled in the distributed actions file.
6425 So you'd like to turn it on in your private,
6426 update-safe config, once and for all:
6430 { +<link linkend="filter-fun">filter{fun}</link> }
6431 / # For ALL sites!</screen>
6434 Note that the above is not really a good idea: There are exceptions
6435 to the filters in <filename>default.action</filename> for things that
6436 really shouldn't be filtered, like code on CVS->Web interfaces. Since
6437 <filename>user.action</filename> has the last word, these exceptions
6438 won't be valid for the <quote>fun</quote> filtering specified here.
6442 You might also worry about how your favourite free websites are
6443 funded, and find that they rely on displaying banner advertisements
6444 to survive. So you might want to specifically allow banners for those
6445 sites that you feel provide value to you:
6455 Note that <literal>allow-ads</literal> has been aliased to
6456 <literal>-<link linkend="block">block</link></literal>,
6457 <literal>-<link linkend="filter-banners-by-size">filter{banners-by-size}</link></literal>, and
6458 <literal>-<link linkend="filter-banners-by-link">filter{banners-by-link}</link></literal> above.
6462 Invoke another alias here to force an over-ride of the MIME type <literal>
6463 application/x-sh</literal> which typically would open a download type
6464 dialog. In my case, I want to look at the shell script, and then I can save
6465 it should I choose to.
6473 <filename>user.action</filename> is generally the best place to define
6474 exceptions and additions to the default policies of
6475 <filename>default.action</filename>. Some actions are safe to have their
6476 default policies set here though. So let's set a default policy to have a
6477 <quote>blank</quote> image as opposed to the checkerboard pattern for
6478 <emphasis>ALL</emphasis> sites. <quote>/</quote> of course matches all URL
6483 { +<link linkend="set-image-blocker">set-image-blocker{blank}</link> }
6484 / # ALL sites</screen>
6489 <!-- ~ End section ~ -->
6493 <!-- ~ End section ~ -->
6495 <!-- ~~~~~~~~ New section Header ~~~~~~~~~ -->
6497 <sect1 id="filter-file">
6498 <title>Filter Files</title>
6501 On-the-fly text substitutions need
6502 to be defined in a <quote>filter file</quote>. Once defined, they
6503 can then be invoked as an <quote>action</quote>.
6507 &my-app; supports three different pcrs-based filter actions:
6508 <literal><link linkend="filter">filter</link></literal> to
6509 rewrite the content that is send to the client,
6510 <literal><link linkend="client-header-filter">client-header-filter</link></literal>
6511 to rewrite headers that are send by the client, and
6512 <literal><link linkend="server-header-filter">server-header-filter</link></literal>
6513 to rewrite headers that are send by the server.
6517 &my-app; also supports two tagger actions:
6518 <literal><link linkend="client-header-tagger">client-header-tagger</link></literal>
6520 <literal><link linkend="server-header-tagger">server-header-tagger</link></literal>.
6521 Taggers and filters use the same syntax in the filter files, the difference
6522 is that taggers don't modify the text they are filtering, but use a rewritten
6523 version of the filtered text as tag. The tags can then be used to change the
6524 applying actions through sections with <link linkend="tag-pattern">tag-patterns</link>.
6528 Finally &my-app; supports the
6529 <literal><link linkend="external-filter">external-filter</link></literal> action
6530 to enable <literal><link linkend="external-filter-syntax">external filters</link></literal>
6531 written in proper programming languages.
6536 Multiple filter files can be defined through the <literal> <link
6537 linkend="filterfile">filterfile</link></literal> config directive. The filters
6538 as supplied by the developers are located in
6539 <filename>default.filter</filename>. It is recommended that any locally
6540 defined or modified filters go in a separately defined file such as
6541 <filename>user.filter</filename>.
6545 Common tasks for content filters are to eliminate common annoyances in
6546 HTML and JavaScript, such as pop-up windows,
6547 exit consoles, crippled windows without navigation tools, the
6548 infamous <BLINK> tag etc, to suppress images with certain
6549 width and height attributes (standard banner sizes or web-bugs),
6550 or just to have fun.
6554 Enabled content filters are applied to any content whose
6555 <quote>Content Type</quote> header is recognised as a sign
6556 of text-based content, with the exception of <literal>text/plain</literal>.
6557 Use the <link linkend="FORCE-TEXT-MODE">force-text-mode</link> action
6558 to also filter other content.
6562 Substitutions are made at the source level, so if you want to <quote>roll
6563 your own</quote> filters, you should first be familiar with HTML syntax,
6564 and, of course, regular expressions.
6568 Just like the <link linkend="actions-file">actions files</link>, the
6569 filter file is organized in sections, which are called <emphasis>filters</emphasis>
6570 here. Each filter consists of a heading line, that starts with one of the
6571 <emphasis>keywords</emphasis> <literal>FILTER:</literal>,
6572 <literal>CLIENT-HEADER-FILTER:</literal> or <literal>SERVER-HEADER-FILTER:</literal>
6573 followed by the filter's <emphasis>name</emphasis>, and a short (one line)
6574 <emphasis>description</emphasis> of what it does. Below that line
6575 come the <emphasis>jobs</emphasis>, i.e. lines that define the actual
6576 text substitutions. By convention, the name of a filter
6577 should describe what the filter <emphasis>eliminates</emphasis>. The
6578 comment is used in the <ulink url="http://config.privoxy.org/">web-based
6579 user interface</ulink>.
6583 Once a filter called <replaceable>name</replaceable> has been defined
6584 in the filter file, it can be invoked by using an action of the form
6585 +<literal><link linkend="filter">filter</link>{<replaceable>name</replaceable>}</literal>
6586 in any <link linkend="actions-file">actions file</link>.
6590 Filter definitions start with a header line that contains the filter
6591 type, the filter name and the filter description.
6592 A content filter header line for a filter called <quote>foo</quote> could look
6596 <screen>FILTER: foo Replace all "foo" with "bar"</screen>
6599 Below that line, and up to the next header line, come the jobs that
6600 define what text replacements the filter executes. They are specified
6601 in a syntax that imitates <ulink url="http://www.perl.org/">Perl</ulink>'s
6602 <literal>s///</literal> operator. If you are familiar with Perl, you
6603 will find this to be quite intuitive, and may want to look at the
6604 PCRS documentation for the subtle differences to Perl behaviour.
6608 Most notably, the non-standard option letter <literal>U</literal> is supported,
6609 which turns the default to ungreedy matching (add <literal>?</literal> to
6610 quantifiers to turn them greedy again).
6614 The non-standard option letter <literal>D</literal> (dynamic) allows
6615 to use the variables $host, $origin (the IP address the request came from),
6616 $path, $url and $listen-address (the address on which Privoxy accepted the
6617 client request. Example: 127.0.0.1:8118).
6618 They will be replaced with the value they refer to before the filter
6623 Note that '$' is a bad choice for a delimiter in a dynamic filter as you
6624 might end up with unintended variables if you use a variable name
6625 directly after the delimiter. Variables will be resolved without
6626 escaping anything, therefore you also have to be careful not to chose
6627 delimiters that appear in the replacement text. For example '<' should
6628 be save, while '?' will sooner or later cause conflicts with $url.
6632 The non-standard option letter <literal>T</literal> (trivial) prevents
6633 parsing for backreferences in the substitute. Use it if you want to include
6634 text like '$&' in your substitute without quoting.
6639 <ulink url="http://en.wikipedia.org/wiki/Regular_expressions"><quote>Regular
6640 Expressions</quote></ulink>, you might want to take a look at
6641 the <link linkend="regex">Appendix on regular expressions</link>, and
6642 see the <ulink url="http://perldoc.perl.org/perlre.html">Perl
6644 <ulink url="http://perldoc.perl.org/perlop.html">the
6645 <literal>s///</literal> operator's syntax</ulink> and <ulink
6646 url="http://perldoc.perl.org/perlre.html">Perl-style regular
6647 expressions</ulink> in general.
6648 The below examples might also help to get you started.
6652 <!-- ~~~~~~~~ New section Header ~~~~~~~~~ -->
6654 <sect2 id="filter-file-tut"><title>Filter File Tutorial</title>
6656 Now, let's complete our <quote>foo</quote> content filter. We have already defined
6657 the heading, but the jobs are still missing. Since all it does is to replace
6658 <quote>foo</quote> with <quote>bar</quote>, there is only one (trivial) job
6662 <screen>s/foo/bar/</screen>
6665 But wait! Didn't the comment say that <emphasis>all</emphasis> occurrences
6666 of <quote>foo</quote> should be replaced? Our current job will only take
6667 care of the first <quote>foo</quote> on each page. For global substitution,
6668 we'll need to add the <literal>g</literal> option:
6671 <screen>s/foo/bar/g</screen>
6674 Our complete filter now looks like this:
6677 <screen>FILTER: foo Replace all "foo" with "bar"
6678 s/foo/bar/g</screen>
6681 Let's look at some real filters for more interesting examples. Here you see
6682 a filter that protects against some common annoyances that arise from JavaScript
6683 abuse. Let's look at its jobs one after the other:
6688 FILTER: js-annoyances Get rid of particularly annoying JavaScript abuse
6690 # Get rid of JavaScript referrer tracking. Test page: http://www.randomoddness.com/untitled.htm
6692 s|(<script.*)document\.referrer(.*</script>)|$1"Not Your Business!"$2|Usg</screen>
6695 Following the header line and a comment, you see the job. Note that it uses
6696 <literal>|</literal> as the delimiter instead of <literal>/</literal>, because
6697 the pattern contains a forward slash, which would otherwise have to be escaped
6698 by a backslash (<literal>\</literal>).
6702 Now, let's examine the pattern: it starts with the text <literal><script.*</literal>
6703 enclosed in parentheses. Since the dot matches any character, and <literal>*</literal>
6704 means: <quote>Match an arbitrary number of the element left of myself</quote>, this
6705 matches <quote><script</quote>, followed by <emphasis>any</emphasis> text, i.e.
6706 it matches the whole page, from the start of the first <script> tag.
6710 That's more than we want, but the pattern continues: <literal>document\.referrer</literal>
6711 matches only the exact string <quote>document.referrer</quote>. The dot needed to
6712 be <emphasis>escaped</emphasis>, i.e. preceded by a backslash, to take away its
6713 special meaning as a joker, and make it just a regular dot. So far, the meaning is:
6714 Match from the start of the first <script> tag in a the page, up to, and including,
6715 the text <quote>document.referrer</quote>, if <emphasis>both</emphasis> are present
6716 in the page (and appear in that order).
6720 But there's still more pattern to go. The next element, again enclosed in parentheses,
6721 is <literal>.*</script></literal>. You already know what <literal>.*</literal>
6722 means, so the whole pattern translates to: Match from the start of the first <script>
6723 tag in a page to the end of the last <script> tag, provided that the text
6724 <quote>document.referrer</quote> appears somewhere in between.
6728 This is still not the whole story, since we have ignored the options and the parentheses:
6729 The portions of the page matched by sub-patterns that are enclosed in parentheses, will be
6730 remembered and be available through the variables <literal>$1, $2, ...</literal> in
6731 the substitute. The <literal>U</literal> option switches to ungreedy matching, which means
6732 that the first <literal>.*</literal> in the pattern will only <quote>eat up</quote> all
6733 text in between <quote><script</quote> and the <emphasis>first</emphasis> occurrence
6734 of <quote>document.referrer</quote>, and that the second <literal>.*</literal> will
6735 only span the text up to the <emphasis>first</emphasis> <quote></script></quote>
6736 tag. Furthermore, the <literal>s</literal> option says that the match may span
6737 multiple lines in the page, and the <literal>g</literal> option again means that the
6738 substitution is global.
6742 So, to summarize, the pattern means: Match all scripts that contain the text
6743 <quote>document.referrer</quote>. Remember the parts of the script from
6744 (and including) the start tag up to (and excluding) the string
6745 <quote>document.referrer</quote> as <literal>$1</literal>, and the part following
6746 that string, up to and including the closing tag, as <literal>$2</literal>.
6750 Now the pattern is deciphered, but wasn't this about substituting things? So
6751 lets look at the substitute: <literal>$1"Not Your Business!"$2</literal> is
6752 easy to read: The text remembered as <literal>$1</literal>, followed by
6753 <literal>"Not Your Business!"</literal> (<emphasis>including</emphasis>
6754 the quotation marks!), followed by the text remembered as <literal>$2</literal>.
6755 This produces an exact copy of the original string, with the middle part
6756 (the <quote>document.referrer</quote>) replaced by <literal>"Not Your
6757 Business!"</literal>.
6761 The whole job now reads: Replace <quote>document.referrer</quote> by
6762 <literal>"Not Your Business!"</literal> wherever it appears inside a
6763 <script> tag. Note that this job won't break JavaScript syntax,
6764 since both the original and the replacement are syntactically valid
6765 string objects. The script just won't have access to the referrer
6766 information anymore.
6770 We'll show you two other jobs from the JavaScript taming department, but
6771 this time only point out the constructs of special interest:
6775 # The status bar is for displaying link targets, not pointless blahblah
6777 s/window\.status\s*=\s*(['"]).*?\1/dUmMy=1/ig</screen>
6780 <literal>\s</literal> stands for whitespace characters (space, tab, newline,
6781 carriage return, form feed), so that <literal>\s*</literal> means: <quote>zero
6782 or more whitespace</quote>. The <literal>?</literal> in <literal>.*?</literal>
6783 makes this matching of arbitrary text ungreedy. (Note that the <literal>U</literal>
6784 option is not set). The <literal>['"]</literal> construct means: <quote>a single
6785 <emphasis>or</emphasis> a double quote</quote>. Finally, <literal>\1</literal> is
6786 a back-reference to the first parenthesis just like <literal>$1</literal> above,
6787 with the difference that in the <emphasis>pattern</emphasis>, a backslash indicates
6788 a back-reference, whereas in the <emphasis>substitute</emphasis>, it's the dollar.
6792 So what does this job do? It replaces assignments of single- or double-quoted
6793 strings to the <quote>window.status</quote> object with a dummy assignment
6794 (using a variable name that is hopefully odd enough not to conflict with
6795 real variables in scripts). Thus, it catches many cases where e.g. pointless
6796 descriptions are displayed in the status bar instead of the link target when
6797 you move your mouse over links.
6801 # Kill OnUnload popups. Yummy. Test: http://www.zdnet.com/zdsubs/yahoo/tree/yfs.html
6803 s/(<body [^>]*)onunload(.*>)/$1never$2/iU</screen>
6807 <ulink url="http://www.w3.org/TR/2000/REC-DOM-Level-2-Events-20001113/events.html#Events-eventgroupings-htmlevents">OnUnload
6808 event binding</ulink> in the HTML DOM was a <emphasis>CRIME</emphasis>.
6809 When I close a browser window, I want it to close and die. Basta.
6810 This job replaces the <quote>onunload</quote> attribute in
6811 <quote><body></quote> tags with the dummy word <literal>never</literal>.
6812 Note that the <literal>i</literal> option makes the pattern matching
6813 case-insensitive. Also note that ungreedy matching alone doesn't always guarantee
6814 a minimal match: In the first parenthesis, we had to use <literal>[^>]*</literal>
6815 instead of <literal>.*</literal> to prevent the match from exceeding the
6816 <body> tag if it doesn't contain <quote>OnUnload</quote>, but the page's
6821 The last example is from the fun department:
6825 FILTER: fun Fun text replacements
6827 # Spice the daily news:
6829 s/microsoft(?!\.com)/MicroSuck/ig</screen>
6832 Note the <literal>(?!\.com)</literal> part (a so-called negative lookahead)
6833 in the job's pattern, which means: Don't match, if the string
6834 <quote>.com</quote> appears directly following <quote>microsoft</quote>
6835 in the page. This prevents links to microsoft.com from being trashed, while
6836 still replacing the word everywhere else.
6840 # Buzzword Bingo (example for extended regex syntax)
6842 s* industry[ -]leading \
6844 | customer[ -]focused \
6845 | market[ -]driven \
6846 | award[ -]winning # Comments are OK, too! \
6847 | high[ -]performance \
6848 | solutions[ -]based \
6852 *<font color="red"><b>BINGO!</b></font> \
6856 The <literal>x</literal> option in this job turns on extended syntax, and allows for
6857 e.g. the liberal use of (non-interpreted!) whitespace for nicer formatting.
6865 <!-- ~~~~~~~~ New section Header ~~~~~~~~~ -->
6867 <sect2 id="predefined-filters"><title>The Pre-defined Filters</title>
6871 Note each filter is also listed in the +filter action section above. Please
6872 keep these listings in sync.
6877 The distribution <filename>default.filter</filename> file contains a selection of
6878 pre-defined filters for your convenience:
6883 <term><emphasis>js-annoyances</emphasis></term>
6886 The purpose of this filter is to get rid of particularly annoying JavaScript abuse.
6892 replaces JavaScript references to the browser's referrer information
6893 with the string "Not Your Business!". This compliments the <literal><link
6894 linkend="hide-referrer">hide-referrer</link></literal> action on the content level.
6899 removes the bindings to the DOM's
6900 <ulink url="http://www.w3.org/TR/2000/REC-DOM-Level-2-Events-20001113/events.html#Events-eventgroupings-htmlevents">unload
6901 event</ulink> which we feel has no right to exist and is responsible for most <quote>exit consoles</quote>, i.e.
6902 nasty windows that pop up when you close another one.
6907 removes code that causes new windows to be opened with undesired properties, such as being
6908 full-screen, non-resizeable, without location, status or menu bar etc.
6913 Use with caution. This is an aggressive filter, and can break sites that
6914 rely heavily on JavaScript.
6920 <term><emphasis>js-events</emphasis></term>
6923 This is a very radical measure. It removes virtually all JavaScript event bindings, which
6924 means that scripts can not react to user actions such as mouse movements or clicks, window
6925 resizing etc, anymore. Use with caution!
6928 We <emphasis>strongly discourage</emphasis> using this filter as a default since it breaks
6929 many legitimate scripts. It is meant for use only on extra-nasty sites (should you really
6936 <term><emphasis>html-annoyances</emphasis></term>
6939 This filter will undo many common instances of HTML based abuse.
6942 The <literal>BLINK</literal> and <literal>MARQUEE</literal> tags
6943 are neutralized (yeah baby!), and browser windows will be created as
6944 resizeable (as of course they should be!), and will have location,
6945 scroll and menu bars -- even if specified otherwise.
6951 <term><emphasis>content-cookies</emphasis></term>
6954 Most cookies are set in the HTTP dialog, where they can be intercepted
6956 <literal><link linkend="crunch-incoming-cookies">crunch-incoming-cookies</link></literal>
6957 and <literal><link linkend="crunch-outgoing-cookies">crunch-outgoing-cookies</link></literal>
6958 actions. But web sites increasingly make use of HTML meta tags and JavaScript
6959 to sneak cookies to the browser on the content level.
6962 This filter disables most HTML and JavaScript code that reads or sets
6963 cookies. It cannot detect all clever uses of these types of code, so it
6964 should not be relied on as an absolute fix. Use it wherever you would also
6965 use the cookie crunch actions.
6971 <term><emphasis>refresh-tags</emphasis></term>
6974 Disable any refresh tags if the interval is greater than nine seconds (so
6975 that redirections done via refresh tags are not destroyed). This is useful
6976 for dial-on-demand setups, or for those who find this HTML feature
6983 <term><emphasis>unsolicited-popups</emphasis></term>
6986 This filter attempts to prevent only <quote>unsolicited</quote> pop-up
6987 windows from opening, yet still allow pop-up windows that the user
6988 has explicitly chosen to open. It was added in version 3.0.1,
6989 as an improvement over earlier such filters.
6992 Technical note: The filter works by redefining the window.open JavaScript
6993 function to a dummy function, <literal>PrivoxyWindowOpen()</literal>,
6994 during the loading and rendering phase of each HTML page access, and
6995 restoring the function afterward.
6998 This is recommended only for browsers that cannot perform this function
6999 reliably themselves. And be aware that some sites require such windows
7000 in order to function normally. Use with caution.
7006 <term><emphasis>all-popups</emphasis></term>
7009 Attempt to prevent <emphasis>all</emphasis> pop-up windows from opening.
7010 Note this should be used with even more discretion than the above, since
7011 it is more likely to break some sites that require pop-ups for normal
7012 usage. Use with caution.
7018 <term><emphasis>img-reorder</emphasis></term>
7021 This is a helper filter that has no value if used alone. It makes the
7022 <literal>banners-by-size</literal> and <literal>banners-by-link</literal>
7023 (see below) filters more effective and should be enabled together with them.
7029 <term><emphasis>banners-by-size</emphasis></term>
7032 This filter removes image tags purely based on what size they are. Fortunately
7033 for us, many ads and banner images tend to conform to certain standardized
7034 sizes, which makes this filter quite effective for ad stripping purposes.
7037 Occasionally this filter will cause false positives on images that are not ads,
7038 but just happen to be of one of the standard banner sizes.
7041 Recommended only for those who require extreme ad blocking. The default
7042 block rules should catch 95+% of all ads <emphasis>without</emphasis> this filter enabled.
7048 <term><emphasis>banners-by-link</emphasis></term>
7051 This is an experimental filter that attempts to kill any banners if
7052 their URLs seem to point to known or suspected click trackers. It is currently
7053 not of much value and is not recommended for use by default.
7059 <term><emphasis>webbugs</emphasis></term>
7062 Webbugs are small, invisible images (technically 1X1 GIF images), that
7063 are used to track users across websites, and collect information on them.
7064 As an HTML page is loaded by the browser, an embedded image tag causes the
7065 browser to contact a third-party site, disclosing the tracking information
7066 through the requested URL and/or cookies for that third-party domain, without
7067 the user ever becoming aware of the interaction with the third-party site.
7068 HTML-ized spam also uses a similar technique to verify email addresses.
7071 This filter removes the HTML code that loads such <quote>webbugs</quote>.
7077 <term><emphasis>tiny-textforms</emphasis></term>
7080 A rather special-purpose filter that can be used to enlarge textareas (those
7081 multi-line text boxes in web forms) and turn off hard word wrap in them.
7082 It was written for the sourceforge.net tracker system where such boxes are
7083 a nuisance, but it can be handy on other sites, too.
7086 It is not recommended to use this filter as a default.
7092 <term><emphasis>jumping-windows</emphasis></term>
7095 Many consider windows that move, or resize themselves to be abusive. This filter
7096 neutralizes the related JavaScript code. Note that some sites might not display
7097 or behave as intended when using this filter. Use with caution.
7103 <term><emphasis>frameset-borders</emphasis></term>
7106 Some web designers seem to assume that everyone in the world will view their
7107 web sites using the same browser brand and version, screen resolution etc,
7108 because only that assumption could explain why they'd use static frame sizes,
7109 yet prevent their frames from being resized by the user, should they be too
7110 small to show their whole content.
7113 This filter removes the related HTML code. It should only be applied to sites
7120 <term><emphasis>demoronizer</emphasis></term>
7123 Many Microsoft products that generate HTML use non-standard extensions (read:
7124 violations) of the ISO 8859-1 aka Latin-1 character set. This can cause those
7125 HTML documents to display with errors on standard-compliant platforms.
7128 This filter translates the MS-only characters into Latin-1 equivalents.
7129 It is not necessary when using MS products, and will cause corruption of
7130 all documents that use 8-bit character sets other than Latin-1. It's mostly
7131 worthwhile for Europeans on non-MS platforms, if weird garbage characters
7132 sometimes appear on some pages, or user agents that don't correct for this on
7135 My version of Mozilla (ancient) shows litte square boxes for quote
7136 characters, and apostrophes on moronized pages. So many pages have this, I
7137 can read them fine now. HB 08/27/06
7144 <term><emphasis>shockwave-flash</emphasis></term>
7147 A filter for shockwave haters. As the name suggests, this filter strips code
7148 out of web pages that is used to embed shockwave flash objects.
7156 <term><emphasis>quicktime-kioskmode</emphasis></term>
7159 Change HTML code that embeds Quicktime objects so that kioskmode, which
7160 prevents saving, is disabled.
7166 <term><emphasis>fun</emphasis></term>
7169 Text replacements for subversive browsing fun. Make fun of your favorite
7170 Monopolist or play buzzword bingo.
7176 <term><emphasis>crude-parental</emphasis></term>
7179 A demonstration-only filter that shows how <application>Privoxy</application>
7180 can be used to delete web content on a keyword basis.
7186 <term><emphasis>ie-exploits</emphasis></term>
7189 An experimental collection of text replacements to disable malicious HTML and JavaScript
7190 code that exploits known security holes in Internet Explorer.
7193 Presently, it only protects against Nimda and a cross-site scripting bug, and
7194 would need active maintenance to provide more substantial protection.
7200 <term><emphasis>site-specifics</emphasis></term>
7203 Some web sites have very specific problems, the cure for which doesn't apply
7204 anywhere else, or could even cause damage on other sites.
7207 This is a collection of such site-specific cures which should only be applied
7208 to the sites they were intended for, which is what the supplied
7209 <filename>default.action</filename> file does. Users shouldn't need to change
7210 anything regarding this filter.
7216 <term><emphasis>google</emphasis></term>
7219 A CSS based block for Google text ads. Also removes a width limitation
7220 and the toolbar advertisement.
7226 <term><emphasis>yahoo</emphasis></term>
7229 Another CSS based block, this time for Yahoo text ads. And removes
7230 a width limitation as well.
7236 <term><emphasis>msn</emphasis></term>
7239 Another CSS based block, this time for MSN text ads. And removes
7240 tracking URLs, as well as a width limitation.
7246 <term><emphasis>blogspot</emphasis></term>
7249 Cleans up some Blogspot blogs. Read the fine print before using this one!
7252 This filter also intentionally removes some navigation stuff and sets the
7253 page width to 100%. As a result, some rounded <quote>corners</quote> would
7254 appear to early or not at all and as fixing this would require a browser
7255 that understands background-size (CSS3), they are removed instead.
7261 <term><emphasis>xml-to-html</emphasis></term>
7264 Server-header filter to change the Content-Type from xml to html.
7270 <term><emphasis>html-to-xml</emphasis></term>
7273 Server-header filter to change the Content-Type from html to xml.
7279 <term><emphasis>no-ping</emphasis></term>
7282 Removes the non-standard <literal>ping</literal> attribute from
7283 anchor and area HTML tags.
7289 <term><emphasis>hide-tor-exit-notation</emphasis></term>
7292 Client-header filter to remove the <command>Tor</command> exit node notation
7293 found in Host and Referer headers.
7296 If &my-app; and <command>Tor</command> are chained and &my-app;
7297 is configured to use socks4a, one can use <quote>http://www.example.org.foobar.exit/</quote>
7298 to access the host <quote>www.example.org</quote> through the
7299 <command>Tor</command> exit node <quote>foobar</quote>.
7302 As the HTTP client isn't aware of this notation, it treats the
7303 whole string <quote>www.example.org.foobar.exit</quote> as host and uses it
7304 for the <quote>Host</quote> and <quote>Referer</quote> headers. From the
7305 server's point of view the resulting headers are invalid and can cause problems.
7308 An invalid <quote>Referer</quote> header can trigger <quote>hot-linking</quote>
7309 protections, an invalid <quote>Host</quote> header will make it impossible for
7310 the server to find the right vhost (several domains hosted on the same IP address).
7313 This client-header filter removes the <quote>foo.exit</quote> part in those headers
7314 to prevent the mentioned problems. Note that it only modifies
7315 the HTTP headers, it doesn't make it impossible for the server
7316 to detect your <command>Tor</command> exit node based on the IP address
7317 the request is coming from.
7324 <term><emphasis> </emphasis></term>
7337 <!-- ~~~~~~~~ New section Header ~~~~~~~~~ -->
7338 <sect2 id="external-filter-syntax"><title>External filter syntax</title>
7340 External filters are scripts or programs that can modify the content in
7341 case common <literal><link linkend="filter">filters</link></literal>
7342 aren't powerful enough.
7345 External filters can be written in any language the platform &my-app; runs
7349 They are controlled with the
7350 <literal><link linkend="external-filter">external-filter</link></literal> action
7351 and have to be defined in the <literal><link linkend="filterfile">filterfile</link></literal>
7355 The header looks like any other filter, but instead of pcrs jobs, external
7356 filters contain a single job which can be a program or a shell script (which
7357 may call other scripts or programs).
7360 External filters read the content from STDIN and write the rewritten
7362 The environment variables PRIVOXY_URL, PRIVOXY_PATH, PRIVOXY_HOST,
7363 PRIVOXY_ORIGIN, PRIVOXY_LISTEN_ADDRESS can be used to get some details
7364 about the client request.
7367 &my-app; will temporary store the content to filter in the
7368 <literal><link linkend="temporary-directory">temporary-directory</link></literal>.
7372 EXTERNAL-FILTER: cat Pointless example filter that doesn't actually modify the content
7375 # Incorrect reimplementation of the filter above in POSIX shell.
7377 # Note that it's a single job that spans multiple lines, the line
7378 # breaks are not passed to the shell, thus the semicolons are required.
7380 # If the script isn't trivial, it is recommended to put it into an external file.
7382 # In general, writing external filters entirely in POSIX shell is not
7383 # considered a good idea.
7384 EXTERNAL-FILTER: cat2 Pointless example filter that despite its name may actually modify the content
7390 EXTERNAL-FILTER: rotate-image Rotate an image by 180 degree. Test filter with limited value.
7391 /usr/local/bin/convert - -rotate 180 -
7393 EXTERNAL-FILTER: citation-needed Adds a "[citation needed]" tag to an image. The coordinates may need adjustment.
7394 /usr/local/bin/convert - -pointsize 16 -fill white -annotate +17+418 "[citation needed]" -
7399 Currently external filters are executed with &my-app;'s privileges!
7400 Only use external filters you understand and trust.
7404 External filters are experimental and the syntax may change in the future.
7410 <!-- ~ End section ~ -->
7414 <!-- ~~~~~ New section ~~~~~ -->
7416 <sect1 id="templates">
7417 <title>Privoxy's Template Files</title>
7419 All <application>Privoxy</application> built-in pages, i.e. error pages such as the
7420 <ulink url="http://show-the-404-error.page"><quote>404 - No Such Domain</quote>
7421 error page</ulink>, the <ulink
7422 url="http://ads.bannerserver.example.com/nasty-ads/sponsor.html"><quote>BLOCKED</quote>
7424 and all pages of its <ulink url="http://config.privoxy.org/">web-based
7425 user interface</ulink>, are generated from <emphasis>templates</emphasis>.
7426 (<application>Privoxy</application> must be running for the above links to work as
7431 These templates are stored in a subdirectory of the <link linkend="confdir">configuration
7432 directory</link> called <filename>templates</filename>. On Unixish platforms,
7434 <ulink url="file:///etc/privoxy/templates/"><filename>/etc/privoxy/templates/</filename></ulink>.
7438 The templates are basically normal HTML files, but with place-holders (called symbols
7439 or exports), which <application>Privoxy</application> fills at run time. It
7440 is possible to edit the templates with a normal text editor, should you want
7441 to customize them. (<emphasis>Not recommended for the casual
7442 user</emphasis>). Should you create your own custom templates, you should use
7443 the <filename>config</filename> setting <link linkend="templdir">templdir</link>
7444 to specify an alternate location, so your templates do not get overwritten
7448 Note that just like in configuration files, lines starting
7449 with <literal>#</literal> are ignored when the templates are filled in.
7453 The place-holders are of the form <literal>@name@</literal>, and you will
7454 find a list of available symbols, which vary from template to template,
7455 in the comments at the start of each file. Note that these comments are not
7456 always accurate, and that it's probably best to look at the existing HTML
7457 code to find out which symbols are supported and what they are filled in with.
7461 A special application of this substitution mechanism is to make whole
7462 blocks of HTML code disappear when a specific symbol is set. We use this
7463 for many purposes, one of them being to include the beta warning in all
7464 our user interface (CGI) pages when <application>Privoxy</application>
7465 is in an alpha or beta development stage:
7469 <!-- @if-unstable-start -->
7471 ... beta warning HTML code goes here ...
7473 <!-- if-unstable-end@ --></screen>
7476 If the "unstable" symbol is set, everything in between and including
7477 <literal>@if-unstable-start</literal> and <literal>if-unstable-end@</literal>
7478 will disappear, leaving nothing but an empty comment:
7481 <screen><!-- --></screen>
7484 There's also an if-then-else construct and an <literal>#include</literal>
7485 mechanism, but you'll sure find out if you are inclined to edit the
7490 All templates refer to a style located at
7491 <ulink url="http://config.privoxy.org/send-stylesheet"><literal>http://config.privoxy.org/send-stylesheet</literal></ulink>.
7492 This is, of course, locally served by <application>Privoxy</application>
7493 and the source for it can be found and edited in the
7494 <filename>cgi-style.css</filename> template.
7499 <!-- ~ End section ~ -->
7503 <!-- ~~~~~ New section ~~~~~ -->
7505 <sect1 id="contact"><title>Contacting the Developers, Bug Reporting and Feature
7508 <!-- Include contacting.sgml boilerplate: -->
7510 <!-- end boilerplate -->
7514 <!-- ~ End section ~ -->
7517 <!-- ~~~~~ New section ~~~~~ -->
7518 <sect1 id="copyright"><title>Privoxy Copyright, License and History</title>
7520 <!-- Include copyright.sgml: -->
7522 <!-- end copyright -->
7525 <application>Privoxy</application> is free software; you can
7526 redistribute it and/or modify it under the terms of the
7527 <citetitle>GNU General Public License</citetitle>, version 2,
7528 as published by the Free Software Foundation and included in
7532 <!-- ~~~~~ New section ~~~~~ -->
7533 <sect2 id="license"><title>License</title>
7535 <screen><![ RCDATA [ &GPLv2; ]]></screen>
7538 <!-- ~ End section ~ -->
7541 <!-- ~~~~~ New section ~~~~~ -->
7543 <sect2 id="history"><title>History</title>
7544 <!-- Include history.sgml: -->
7546 <!-- end history -->
7549 <sect2 id="authors"><title>Authors</title>
7550 <!-- Include p-authors.sgml: -->
7552 <!-- end authors -->
7557 <!-- ~ End section ~ -->
7560 <!-- ~~~~~ New section ~~~~~ -->
7561 <sect1 id="seealso"><title>See Also</title>
7562 <!-- Include seealso.sgml: -->
7564 <!-- end seealso -->
7569 <!-- ~~~~~ New section ~~~~~ -->
7570 <sect1 id="appendix"><title>Appendix</title>
7573 <!-- ~~~~~ New section ~~~~~ -->
7575 <title>Regular Expressions</title>
7577 <application>Privoxy</application> uses Perl-style <quote>regular
7578 expressions</quote> in its <link linkend="actions-file">actions
7579 files</link> and <link linkend="filter-file">filter file</link>,
7580 through the <ulink url="http://www.pcre.org/">PCRE</ulink> and
7583 <ulink url="http://www.oesterhelt.org/pcrs/">PCRS</ulink> libraries.
7585 <application>PCRS</application> libraries.
7589 If you are reading this, you probably don't understand what <quote>regular
7590 expressions</quote> are, or what they can do. So this will be a very brief
7591 introduction only. A full explanation would require a <ulink
7592 url="http://www.oreilly.com/catalog/regex/">book</ulink> ;-)
7596 Regular expressions provide a language to describe patterns that can be
7597 run against strings of characters (letter, numbers, etc), to see if they
7598 match the string or not. The patterns are themselves (sometimes complex)
7599 strings of literal characters, combined with wild-cards, and other special
7600 characters, called meta-characters. The <quote>meta-characters</quote> have
7601 special meanings and are used to build complex patterns to be matched against.
7602 Perl Compatible Regular Expressions are an especially convenient
7603 <quote>dialect</quote> of the regular expression language.
7607 To make a simple analogy, we do something similar when we use wild-card
7608 characters when listing files with the <command>dir</command> command in DOS.
7609 <literal>*.*</literal> matches all filenames. The <quote>special</quote>
7610 character here is the asterisk which matches any and all characters. We can be
7611 more specific and use <literal>?</literal> to match just individual
7612 characters. So <quote>dir file?.text</quote> would match
7613 <quote>file1.txt</quote>, <quote>file2.txt</quote>, etc. We are pattern
7614 matching, using a similar technique to <quote>regular expressions</quote>!
7618 Regular expressions do essentially the same thing, but are much, much more
7619 powerful. There are many more <quote>special characters</quote> and ways of
7620 building complex patterns however. Let's look at a few of the common ones,
7621 and then some examples:
7626 <emphasis>.</emphasis> - Matches any single character, e.g. <quote>a</quote>,
7627 <quote>A</quote>, <quote>4</quote>, <quote>:</quote>, or <quote>@</quote>.
7633 <emphasis>?</emphasis> - The preceding character or expression is matched ZERO or ONE
7640 <emphasis>+</emphasis> - The preceding character or expression is matched ONE or MORE
7647 <emphasis>*</emphasis> - The preceding character or expression is matched ZERO or MORE
7654 <emphasis>\</emphasis> - The <quote>escape</quote> character denotes that
7655 the following character should be taken literally. This is used where one of the
7656 special characters (e.g. <quote>.</quote>) needs to be taken literally and
7657 not as a special meta-character. Example: <quote>example\.com</quote>, makes
7658 sure the period is recognized only as a period (and not expanded to its
7659 meta-character meaning of any single character).
7665 <emphasis>[ ]</emphasis> - Characters enclosed in brackets will be matched if
7666 any of the enclosed characters are encountered. For instance, <quote>[0-9]</quote>
7667 matches any numeric digit (zero through nine). As an example, we can combine
7668 this with <quote>+</quote> to match any digit one of more times: <quote>[0-9]+</quote>.
7674 <emphasis>( )</emphasis> - parentheses are used to group a sub-expression,
7675 or multiple sub-expressions.
7681 <emphasis>|</emphasis> - The <quote>bar</quote> character works like an
7682 <quote>or</quote> conditional statement. A match is successful if the
7683 sub-expression on either side of <quote>|</quote> matches. As an example:
7684 <quote>/(this|that) example/</quote> uses grouping and the bar character
7685 and would match either <quote>this example</quote> or <quote>that
7686 example</quote>, and nothing else.
7691 These are just some of the ones you are likely to use when matching URLs with
7692 <application>Privoxy</application>, and is a long way from a definitive
7693 list. This is enough to get us started with a few simple examples which may
7694 be more illuminating:
7698 <emphasis><literal>/.*/banners/.*</literal></emphasis> - A simple example
7699 that uses the common combination of <quote>.</quote> and <quote>*</quote> to
7700 denote any character, zero or more times. In other words, any string at all.
7701 So we start with a literal forward slash, then our regular expression pattern
7702 (<quote>.*</quote>) another literal forward slash, the string
7703 <quote>banners</quote>, another forward slash, and lastly another
7704 <quote>.*</quote>. We are building
7705 a directory path here. This will match any file with the path that has a
7706 directory named <quote>banners</quote> in it. The <quote>.*</quote> matches
7707 any characters, and this could conceivably be more forward slashes, so it
7708 might expand into a much longer looking path. For example, this could match:
7709 <quote>/eye/hate/spammers/banners/annoy_me_please.gif</quote>, or just
7710 <quote>/banners/annoying.html</quote>, or almost an infinite number of other
7711 possible combinations, just so it has <quote>banners</quote> in the path
7716 And now something a little more complex:
7720 <emphasis><literal>/.*/adv((er)?ts?|ertis(ing|ements?))?/</literal></emphasis> -
7721 We have several literal forward slashes again (<quote>/</quote>), so we are
7722 building another expression that is a file path statement. We have another
7723 <quote>.*</quote>, so we are matching against any conceivable sub-path, just so
7724 it matches our expression. The only true literal that <emphasis>must
7725 match</emphasis> our pattern is <application>adv</application>, together with
7726 the forward slashes. What comes after the <quote>adv</quote> string is the
7731 Remember the <quote>?</quote> means the preceding expression (either a
7732 literal character or anything grouped with <quote>(...)</quote> in this case)
7733 can exist or not, since this means either zero or one match. So
7734 <quote>((er)?ts?|ertis(ing|ements?))</quote> is optional, as are the
7735 individual sub-expressions: <quote>(er)</quote>,
7736 <quote>(ing|ements?)</quote>, and the <quote>s</quote>. The <quote>|</quote>
7737 means <quote>or</quote>. We have two of those. For instance,
7738 <quote>(ing|ements?)</quote>, can expand to match either <quote>ing</quote>
7739 <emphasis>OR</emphasis> <quote>ements?</quote>. What is being done here, is an
7740 attempt at matching as many variations of <quote>advertisement</quote>, and
7741 similar, as possible. So this would expand to match just <quote>adv</quote>,
7742 or <quote>advert</quote>, or <quote>adverts</quote>, or
7743 <quote>advertising</quote>, or <quote>advertisement</quote>, or
7744 <quote>advertisements</quote>. You get the idea. But it would not match
7745 <quote>advertizements</quote> (with a <quote>z</quote>). We could fix that by
7746 changing our regular expression to:
7747 <quote>/.*/adv((er)?ts?|erti(s|z)(ing|ements?))?/</quote>, which would then match
7752 <emphasis><literal>/.*/advert[0-9]+\.(gif|jpe?g)</literal></emphasis> - Again
7753 another path statement with forward slashes. Anything in the square brackets
7754 <quote>[ ]</quote> can be matched. This is using <quote>0-9</quote> as a
7755 shorthand expression to mean any digit one through nine. It is the same as
7756 saying <quote>0123456789</quote>. So any digit matches. The <quote>+</quote>
7757 means one or more of the preceding expression must be included. The preceding
7758 expression here is what is in the square brackets -- in this case, any digit
7759 one through nine. Then, at the end, we have a grouping: <quote>(gif|jpe?g)</quote>.
7760 This includes a <quote>|</quote>, so this needs to match the expression on
7761 either side of that bar character also. A simple <quote>gif</quote> on one side, and the other
7762 side will in turn match either <quote>jpeg</quote> or <quote>jpg</quote>,
7763 since the <quote>?</quote> means the letter <quote>e</quote> is optional and
7764 can be matched once or not at all. So we are building an expression here to
7765 match image GIF or JPEG type image file. It must include the literal
7766 string <quote>advert</quote>, then one or more digits, and a <quote>.</quote>
7767 (which is now a literal, and not a special character, since it is escaped
7768 with <quote>\</quote>), and lastly either <quote>gif</quote>, or
7769 <quote>jpeg</quote>, or <quote>jpg</quote>. Some possible matches would
7770 include: <quote>//advert1.jpg</quote>,
7771 <quote>/nasty/ads/advert1234.gif</quote>,
7772 <quote>/banners/from/hell/advert99.jpg</quote>. It would not match
7773 <quote>advert1.gif</quote> (no leading slash), or
7774 <quote>/adverts232.jpg</quote> (the expression does not include an
7775 <quote>s</quote>), or <quote>/advert1.jsp</quote> (<quote>jsp</quote> is not
7776 in the expression anywhere).
7780 We are barely scratching the surface of regular expressions here so that you
7781 can understand the default <application>Privoxy</application>
7782 configuration files, and maybe use this knowledge to customize your own
7783 installation. There is much, much more that can be done with regular
7784 expressions. Now that you know enough to get started, you can learn more on
7789 More reading on Perl Compatible Regular expressions:
7790 <ulink url="http://perldoc.perl.org/perlre.html">http://perldoc.perl.org/perlre.html</ulink>
7794 For information on regular expression based substitutions and their applications
7795 in filters, please see the <link linkend="filter-file">filter file tutorial</link>
7800 <!-- ~ End section ~ -->
7803 <!-- ~~~~~ New section ~~~~~ -->
7804 <sect2 id="internal-pages">
7805 <title>Privoxy's Internal Pages</title>
7808 Since <application>Privoxy</application> proxies each requested
7809 web page, it is easy for <application>Privoxy</application> to
7810 trap certain special URLs. In this way, we can talk directly to
7811 <application>Privoxy</application>, and see how it is
7812 configured, see how our rules are being applied, change these
7813 rules and other configuration options, and even turn
7814 <application>Privoxy's</application> filtering off, all with
7819 The URLs listed below are the special ones that allow direct access
7820 to <application>Privoxy</application>. Of course,
7821 <application>Privoxy</application> must be running to access these. If
7822 not, you will get a friendly error message. Internet access is not
7834 <ulink url="http://config.privoxy.org/">http://config.privoxy.org/</ulink>
7838 There is a shortcut: <ulink url="http://p.p/">http://p.p/</ulink> (But it
7839 doesn't provide a fall-back to a real page, in case the request is not
7840 sent through <application>Privoxy</application>)
7846 Show information about the current configuration, including viewing and
7847 editing of actions files:
7851 <ulink url="http://config.privoxy.org/show-status">http://config.privoxy.org/show-status</ulink>
7858 Show the source code version numbers:
7862 <ulink url="http://config.privoxy.org/show-version">http://config.privoxy.org/show-version</ulink>
7869 Show the browser's request headers:
7873 <ulink url="http://config.privoxy.org/show-request">http://config.privoxy.org/show-request</ulink>
7880 Show which actions apply to a URL and why:
7884 <ulink url="http://config.privoxy.org/show-url-info">http://config.privoxy.org/show-url-info</ulink>
7891 Toggle Privoxy on or off. This feature can be turned off/on in the main
7892 <filename>config</filename> file. When toggled <quote>off</quote>, <quote>Privoxy</quote>
7893 continues to run, but only as a pass-through proxy, with no actions taking
7898 <ulink url="http://config.privoxy.org/toggle">http://config.privoxy.org/toggle</ulink>
7902 Short cuts. Turn off, then on:
7906 <ulink url="http://config.privoxy.org/toggle?set=disable">http://config.privoxy.org/toggle?set=disable</ulink>
7911 <ulink url="http://config.privoxy.org/toggle?set=enable">http://config.privoxy.org/toggle?set=enable</ulink>
7921 <!-- ~~~~~ New section ~~~~~ -->
7923 <title>Chain of Events</title>
7925 Let's take a quick look at how some of <application>Privoxy's</application>
7926 core features are triggered, and the ensuing sequence of events when a web
7927 page is requested by your browser:
7933 First, your web browser requests a web page. The browser knows to send
7934 the request to <application>Privoxy</application>, which will in turn,
7935 relay the request to the remote web server after passing the following
7941 <application>Privoxy</application> traps any request for its own internal CGI
7942 pages (e.g <ulink url="http://p.p/">http://p.p/</ulink>) and sends the CGI page back to the browser.
7947 Next, <application>Privoxy</application> checks to see if the URL
7949 linkend="BLOCK"><quote>+block</quote></link> patterns. If
7950 so, the URL is then blocked, and the remote web server will not be contacted.
7951 <link linkend="HANDLE-AS-IMAGE"><quote>+handle-as-image</quote></link>
7953 <link linkend="HANDLE-AS-EMPTY-DOCUMENT"><quote>+handle-as-empty-document</quote></link>
7954 are then checked, and if there is no match, an
7955 HTML <quote>BLOCKED</quote> page is sent back to the browser. Otherwise, if
7956 it does match, an image is returned for the former, and an empty text
7957 document for the latter. The type of image would depend on the setting of
7958 <link linkend="SET-IMAGE-BLOCKER"><quote>+set-image-blocker</quote></link>
7959 (blank, checkerboard pattern, or an HTTP redirect to an image elsewhere).
7964 Untrusted URLs are blocked. If URLs are being added to the
7965 <filename>trust</filename> file, then that is done.
7970 If the URL pattern matches the <link
7971 linkend="FAST-REDIRECTS"><quote>+fast-redirects</quote></link> action,
7972 it is then processed. Unwanted parts of the requested URL are stripped.
7977 Now the rest of the client browser's request headers are processed. If any
7978 of these match any of the relevant actions (e.g. <link
7979 linkend="HIDE-USER-AGENT"><quote>+hide-user-agent</quote></link>,
7980 etc.), headers are suppressed or forged as determined by these actions and
7986 Now the web server starts sending its response back (i.e. typically a web
7992 First, the server headers are read and processed to determine, among other
7993 things, the MIME type (document type) and encoding. The headers are then
7994 filtered as determined by the
7995 <link linkend="CRUNCH-INCOMING-COOKIES"><quote>+crunch-incoming-cookies</quote></link>,
7996 <link linkend="SESSION-COOKIES-ONLY"><quote>+session-cookies-only</quote></link>,
7997 and <link linkend="DOWNGRADE-HTTP-VERSION"><quote>+downgrade-http-version</quote></link>
8003 If any <link linkend="FILTER"><quote>+filter</quote></link> action
8005 linkend="DEANIMATE-GIFS"><quote>+deanimate-gifs</quote></link>
8006 action applies (and the document type fits the action), the rest of the page is
8007 read into memory (up to a configurable limit). Then the filter rules (from
8008 <filename>default.filter</filename> and any other filter files) are
8009 processed against the buffered content. Filters are applied in the order
8010 they are specified in one of the filter files. Animated GIFs, if present,
8011 are reduced to either the first or last frame, depending on the action
8012 setting.The entire page, which is now filtered, is then sent by
8013 <application>Privoxy</application> back to your browser.
8016 If neither a <link linkend="FILTER"><quote>+filter</quote></link> action
8018 linkend="DEANIMATE-GIFS"><quote>+deanimate-gifs</quote></link>
8019 matches, then <application>Privoxy</application> passes the raw data through
8020 to the client browser as it becomes available.
8025 As the browser receives the now (possibly filtered) page content, it
8026 reads and then requests any URLs that may be embedded within the page
8027 source, e.g. ad images, stylesheets, JavaScript, other HTML documents (e.g.
8028 frames), sounds, etc. For each of these objects, the browser issues a
8029 separate request (this is easily viewable in <application>Privoxy's</application>
8030 logs). And each such request is in turn processed just as above. Note that a
8031 complex web page will have many, many such embedded URLs. If these
8032 secondary requests are to a different server, then quite possibly a very
8033 differing set of actions is triggered.
8040 NOTE: This is somewhat of a simplistic overview of what happens with each URL
8041 request. For the sake of brevity and simplicity, we have focused on
8042 <application>Privoxy's</application> core features only.
8048 <!-- ~~~~~ New section ~~~~~ -->
8049 <sect2 id="actionsanat">
8050 <title>Troubleshooting: Anatomy of an Action</title>
8053 The way <application>Privoxy</application> applies
8054 <link linkend="ACTIONS">actions</link> and <link linkend="FILTER">filters</link>
8055 to any given URL can be complex, and not always so
8056 easy to understand what is happening. And sometimes we need to be able to
8057 <emphasis>see</emphasis> just what <application>Privoxy</application> is
8058 doing. Especially, if something <application>Privoxy</application> is doing
8059 is causing us a problem inadvertently. It can be a little daunting to look at
8060 the actions and filters files themselves, since they tend to be filled with
8061 <link linkend="regex">regular expressions</link> whose consequences are not
8066 One quick test to see if <application>Privoxy</application> is causing a problem
8067 or not, is to disable it temporarily. This should be the first troubleshooting
8068 step (be sure to flush caches afterward!). Looking at the
8069 logs is a good idea too. (Note that both the toggle feature and logging are
8070 enabled via <filename>config</filename> file settings, and may need to be
8071 turned <quote>on</quote>.)
8074 Another easy troubleshooting step to try is if you have done any
8075 customization of your installation, revert back to the installed
8076 defaults and see if that helps. There are times the developers get complaints
8077 about one thing or another, and the problem is more related to a customized
8078 configuration issue.
8082 <application>Privoxy</application> also provides the
8083 <ulink url="http://config.privoxy.org/show-url-info">http://config.privoxy.org/show-url-info</ulink>
8084 page that can show us very specifically how <application>actions</application>
8085 are being applied to any given URL. This is a big help for troubleshooting.
8089 First, enter one URL (or partial URL) at the prompt, and then
8090 <application>Privoxy</application> will tell us
8091 how the current configuration will handle it. This will not
8092 help with filtering effects (i.e. the <link
8093 linkend="FILTER"><quote>+filter</quote></link> action) from
8094 one of the filter files since this is handled very
8095 differently and not so easy to trap! It also will not tell you about any other
8096 URLs that may be embedded within the URL you are testing. For instance, images
8097 such as ads are expressed as URLs within the raw page source of HTML pages. So
8098 you will only get info for the actual URL that is pasted into the prompt area
8099 -- not any sub-URLs. If you want to know about embedded URLs like ads, you
8100 will have to dig those out of the HTML source. Use your browser's <quote>View
8101 Page Source</quote> option for this. Or right click on the ad, and grab the
8106 Let's try an example, <ulink url="http://google.com">google.com</ulink>,
8107 and look at it one section at a time in a sample configuration (your real
8108 configuration may vary):
8112 Matches for http://www.google.com:
8114 In file: default.action <guibutton>[ View ]</guibutton> <guibutton>[ Edit ]</guibutton>
8116 {+change-x-forwarded-for{block}
8117 +deanimate-gifs {last}
8118 +fast-redirects {check-decoded-url}
8119 +filter {refresh-tags}
8120 +filter {img-reorder}
8121 +filter {banners-by-size}
8123 +filter {jumping-windows}
8124 +filter {ie-exploits}
8125 +hide-from-header {block}
8126 +hide-referrer {forge}
8127 +session-cookies-only
8128 +set-image-blocker {pattern}
8131 { -session-cookies-only }
8137 In file: user.action <guibutton>[ View ]</guibutton> <guibutton>[ Edit ]</guibutton>
8138 (no matches in this file)
8142 This is telling us how we have defined our
8143 <link linkend="ACTIONS"><quote>actions</quote></link>, and
8144 which ones match for our test case, <quote>google.com</quote>.
8145 Displayed is all the actions that are available to us. Remember,
8146 the <literal>+</literal> sign denotes <quote>on</quote>. <literal>-</literal>
8147 denotes <quote>off</quote>. So some are <quote>on</quote> here, but many
8148 are <quote>off</quote>. Each example we try may provide a slightly different
8149 end result, depending on our configuration directives.
8153 is for our <filename>default.action</filename> file. The large, multi-line
8154 listing, is how the actions are set to match for all URLs, i.e. our default
8155 settings. If you look at your <quote>actions</quote> file, this would be the
8156 section just below the <quote>aliases</quote> section near the top. This
8157 will apply to all URLs as signified by the single forward slash at the end
8158 of the listing -- <quote> / </quote>.
8162 But we have defined additional actions that would be exceptions to these general
8163 rules, and then we list specific URLs (or patterns) that these exceptions
8164 would apply to. Last match wins. Just below this then are two explicit
8165 matches for <quote>.google.com</quote>. The first is negating our previous
8166 cookie setting, which was for <link
8167 linkend="SESSION-COOKIES-ONLY"><quote>+session-cookies-only</quote></link>
8168 (i.e. not persistent). So we will allow persistent cookies for google, at
8169 least that is how it is in this example. The second turns
8170 <emphasis>off</emphasis> any <link
8171 linkend="FAST-REDIRECTS"><quote>+fast-redirects</quote></link>
8172 action, allowing this to take place unmolested. Note that there is a leading
8173 dot here -- <quote>.google.com</quote>. This will match any hosts and
8174 sub-domains, in the google.com domain also, such as
8175 <quote>www.google.com</quote> or <quote>mail.google.com</quote>. But it would not
8176 match <quote>www.google.de</quote>! So, apparently, we have these two actions
8177 defined as exceptions to the general rules at the top somewhere in the lower
8178 part of our <filename>default.action</filename> file, and
8179 <quote>google.com</quote> is referenced somewhere in these latter sections.
8183 Then, for our <filename>user.action</filename> file, we again have no hits.
8184 So there is nothing google-specific that we might have added to our own, local
8185 configuration. If there was, those actions would over-rule any actions from
8186 previously processed files, such as <filename>default.action</filename>.
8187 <filename>user.action</filename> typically has the last word. This is the
8188 best place to put hard and fast exceptions,
8192 And finally we pull it all together in the bottom section and summarize how
8193 <application>Privoxy</application> is applying all its <quote>actions</quote>
8194 to <quote>google.com</quote>:
8202 +change-x-forwarded-for{block}
8203 -client-header-filter{hide-tor-exit-notation}
8204 -content-type-overwrite
8205 -crunch-client-header
8206 -crunch-if-none-match
8207 -crunch-incoming-cookies
8208 -crunch-outgoing-cookies
8209 -crunch-server-header
8210 +deanimate-gifs {last}
8211 -downgrade-http-version
8214 -filter {content-cookies}
8215 -filter {all-popups}
8216 -filter {banners-by-link}
8217 -filter {tiny-textforms}
8218 -filter {frameset-borders}
8219 -filter {demoronizer}
8220 -filter {shockwave-flash}
8221 -filter {quicktime-kioskmode}
8223 -filter {crude-parental}
8224 -filter {site-specifics}
8225 -filter {js-annoyances}
8226 -filter {html-annoyances}
8227 +filter {refresh-tags}
8228 -filter {unsolicited-popups}
8229 +filter {img-reorder}
8230 +filter {banners-by-size}
8232 +filter {jumping-windows}
8233 +filter {ie-exploits}
8240 -handle-as-empty-document
8242 -hide-accept-language
8243 -hide-content-disposition
8244 +hide-from-header {block}
8245 -hide-if-modified-since
8246 +hide-referrer {forge}
8249 -overwrite-last-modified
8250 -prevent-compression
8252 -server-header-filter{xml-to-html}
8253 -server-header-filter{html-to-xml}
8254 -session-cookies-only
8255 +set-image-blocker {pattern} </screen>
8258 Notice the only difference here to the previous listing, is to
8259 <quote>fast-redirects</quote> and <quote>session-cookies-only</quote>,
8260 which are activated specifically for this site in our configuration,
8261 and thus show in the <quote>Final Results</quote>.
8265 Now another example, <quote>ad.doubleclick.net</quote>:
8269 { +block{Domains starts with "ad"} }
8272 { +block{Domain contains "ad"} }
8275 { +block{Doubleclick banner server} +handle-as-image }
8276 .[a-vx-z]*.doubleclick.net
8280 We'll just show the interesting part here - the explicit matches. It is
8281 matched three different times. Two <quote>+block{}</quote> sections,
8282 and a <quote>+block{} +handle-as-image</quote>,
8283 which is the expanded form of one of our aliases that had been defined as:
8284 <quote>+block-as-image</quote>. (<link
8285 linkend="ALIASES"><quote>Aliases</quote></link> are defined in
8286 the first section of the actions file and typically used to combine more
8291 Any one of these would have done the trick and blocked this as an unwanted
8292 image. This is unnecessarily redundant since the last case effectively
8293 would also cover the first. No point in taking chances with these guys
8294 though ;-) Note that if you want an ad or obnoxious
8295 URL to be invisible, it should be defined as <quote>ad.doubleclick.net</quote>
8296 is done here -- as both a <link
8297 linkend="BLOCK"><quote>+block{}</quote></link>
8298 <emphasis>and</emphasis> an
8299 <link linkend="HANDLE-AS-IMAGE"><quote>+handle-as-image</quote></link>.
8300 The custom alias <quote><literal>+block-as-image</literal></quote> just
8301 simplifies the process and make it more readable.
8305 One last example. Let's try <quote>http://www.example.net/adsl/HOWTO/</quote>.
8306 This one is giving us problems. We are getting a blank page. Hmmm ...
8310 Matches for http://www.example.net/adsl/HOWTO/:
8312 In file: default.action <guibutton>[ View ]</guibutton> <guibutton>[ Edit ]</guibutton>
8316 +change-x-forwarded-for{block}
8317 -client-header-filter{hide-tor-exit-notation}
8318 -content-type-overwrite
8319 -crunch-client-header
8320 -crunch-if-none-match
8321 -crunch-incoming-cookies
8322 -crunch-outgoing-cookies
8323 -crunch-server-header
8325 -downgrade-http-version
8326 +fast-redirects {check-decoded-url}
8328 -filter {content-cookies}
8329 -filter {all-popups}
8330 -filter {banners-by-link}
8331 -filter {tiny-textforms}
8332 -filter {frameset-borders}
8333 -filter {demoronizer}
8334 -filter {shockwave-flash}
8335 -filter {quicktime-kioskmode}
8337 -filter {crude-parental}
8338 -filter {site-specifics}
8339 -filter {js-annoyances}
8340 -filter {html-annoyances}
8341 +filter {refresh-tags}
8342 -filter {unsolicited-popups}
8343 +filter {img-reorder}
8344 +filter {banners-by-size}
8346 +filter {jumping-windows}
8347 +filter {ie-exploits}
8354 -handle-as-empty-document
8356 -hide-accept-language
8357 -hide-content-disposition
8358 +hide-from-header{block}
8359 +hide-referer{forge}
8361 -overwrite-last-modified
8362 +prevent-compression
8364 -server-header-filter{xml-to-html}
8365 -server-header-filter{html-to-xml}
8366 +session-cookies-only
8367 +set-image-blocker{blank} }
8370 { +block{Path contains "ads".} +handle-as-image }
8375 Ooops, the <quote>/adsl/</quote> is matching <quote>/ads</quote> in our
8376 configuration! But we did not want this at all! Now we see why we get the
8377 blank page. It is actually triggering two different actions here, and
8378 the effects are aggregated so that the URL is blocked, and &my-app; is told
8379 to treat the block as if it were an image. But this is, of course, all wrong.
8380 We could now add a new action below this (or better in our own
8381 <filename>user.action</filename> file) that explicitly
8382 <emphasis>un</emphasis> blocks (
8383 <link linkend="BLOCK"><quote>{-block}</quote></link>) paths with
8384 <quote>adsl</quote> in them (remember, last match in the configuration
8385 wins). There are various ways to handle such exceptions. Example:
8394 Now the page displays ;-)
8395 Remember to flush your browser's caches when making these kinds of changes to
8396 your configuration to insure that you get a freshly delivered page! Or, try
8397 using <literal>Shift+Reload</literal>.
8401 But now what about a situation where we get no explicit matches like
8406 { +block{Path starts with "ads".} +handle-as-image }
8411 That actually was very helpful and pointed us quickly to where the problem
8412 was. If you don't get this kind of match, then it means one of the default
8413 rules in the first section of <filename>default.action</filename> is causing
8414 the problem. This would require some guesswork, and maybe a little trial and
8415 error to isolate the offending rule. One likely cause would be one of the
8416 <link linkend="FILTER"><quote>+filter</quote></link> actions.
8417 These tend to be harder to troubleshoot.
8418 Try adding the URL for the site to one of aliases that turn off
8419 <link linkend="FILTER"><quote>+filter</quote></link>:
8425 .worldpay.com # for quietpc.com
8432 <quote><literal>{ shop }</literal></quote> is an <quote>alias</quote> that expands to
8433 <quote><literal>{ -filter -session-cookies-only }</literal></quote>.
8434 Or you could do your own exception to negate filtering:
8439 # Disable ALL filter actions for sites in this section
8446 This would turn off all filtering for these sites. This is best
8447 put in <filename>user.action</filename>, for local site
8448 exceptions. Note that when a simple domain pattern is used by itself (without
8449 the subsequent path portion), all sub-pages within that domain are included
8450 automatically in the scope of the action.
8454 Images that are inexplicably being blocked, may well be hitting the
8455 <link linkend="FILTER-BANNERS-BY-SIZE"><quote>+filter{banners-by-size}</quote></link>
8457 that images of certain sizes are ad banners (works well
8458 <emphasis>most of the time</emphasis> since these tend to be standardized).
8462 <quote><literal>{ fragile }</literal></quote> is an alias that disables most
8463 actions that are the most likely to cause trouble. This can be used as a
8464 last resort for problem sites.
8469 # Handle with care: easy to break
8471 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,
projects / privoxy.git / blob