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5 <!entity p-intro SYSTEM "privoxy.sgml">
6 <!entity seealso SYSTEM "seealso.sgml">
7 <!entity buildsource SYSTEM "buildsource.sgml">
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10 <!entity copyright SYSTEM "copyright.sgml">
11 <!entity license SYSTEM "license.sgml">
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13 <!entity GPLv3 SYSTEM "../../LICENSE.GPLv3">
14 <!entity p-authors SYSTEM "p-authors.sgml">
15 <!entity config SYSTEM "p-config.sgml">
16 <!entity changelog SYSTEM "changelog.sgml">
17 <!entity p-version "3.0.33">
18 <!entity p-status "UNRELEASED">
19 <!entity % p-authors-formal "INCLUDE"> <!-- include additional text, etc -->
20 <!entity % p-not-stable "INCLUDE">
21 <!entity % p-stable "IGNORE">
22 <!entity % p-text "IGNORE"> <!-- define we are not a text only doc -->
23 <!entity % p-doc "INCLUDE"> <!-- and we are a formal doc -->
24 <!entity % p-readme "IGNORE">
25 <!entity % user-man "IGNORE">
26 <!entity % config-file "IGNORE">
27 <!entity % p-supp-userman "IGNORE"> <!-- Omit some from supported.sgml -->
28 <!entity my-copy "©"> <!-- kludge for docbook2man -->
29 <!entity % draft "IGNORE"> <!-- WIP stuff -->
30 <!entity % seealso-extra "INCLUDE"> <!-- extra stuff from seealso.sgml -->
31 <!entity my-app "<application>Privoxy</application>">
34 File : doc/source/user-manual.sgml
38 Copyright (C) 2001-2021 Privoxy Developers https://www.privoxy.org/
41 ========================================================================
42 NOTE: Please read developer-manual/documentation.html before touching
43 anything in this, or other Privoxy documentation.
44 ========================================================================
51 <title>Privoxy &p-version; User Manual</title>
55 <!-- Completely the wrong markup, but very little is allowed -->
56 <!-- in this part of an article. FIXME -->
57 <link linkend="copyright">Copyright</link> &my-copy; 2001-2021 by
58 <ulink url="https://www.privoxy.org/">Privoxy Developers</ulink>
64 Note: the following should generate a separate page, and a live link to it,
65 all nicely done. But it doesn't for some mysterious reason. Please leave
66 commented unless it can be fixed proper. For the time being, the
67 copyright/license declarations will be in their own sgml.
80 This is here to keep vim syntax file from breaking :/
81 If I knew enough to fix it, I would.
82 PLEASE DO NOT REMOVE! HB: hal@foobox.net
88 The <citetitle>Privoxy User Manual</citetitle> gives users information on how to
89 install, configure and use <ulink
90 url="https://www.privoxy.org/">Privoxy</ulink>.
93 <!-- Include privoxy.sgml boilerplate: -->
95 <!-- end privoxy.sgml -->
98 You can find the latest version of the <citetitle>Privoxy User Manual</citetitle> at <ulink
99 url="https://www.privoxy.org/user-manual/">https://www.privoxy.org/user-manual/</ulink>.
100 Please see the <link linkend="contact">Contact section</link> on how to
101 contact the developers.
108 <!-- ~~~~~ New section ~~~~~ -->
109 <sect1 label="1" id="introduction"><title>Introduction</title>
111 This documentation is included with the current &p-status; version of
112 <application>Privoxy</application>, &p-version;<![%p-not-stable;[,
113 and is mostly complete at this point. The most up to date reference for the
114 time being is still the comments in the source files and in the individual
115 configuration files. Development of a new version is currently nearing
116 completion, and includes significant changes and enhancements over
120 <!-- include only in non-stable versions -->
123 Since this is a &p-status; version, not all new features are well tested. This
124 documentation may be slightly out of sync as a result (especially with
125 <ulink url="https://www.privoxy.org/gitweb/?p=privoxy.git;a=summary">git sources</ulink>).
126 And there <emphasis>may be</emphasis> bugs, though hopefully
131 <!-- ~~~~~ New section ~~~~~ -->
132 <sect2 id="features"><title>Features</title>
134 In addition to the core
135 features of ad blocking and
136 <ulink url="https://en.wikipedia.org/wiki/Browser_cookie">cookie</ulink> management,
137 <application>Privoxy</application> provides many supplemental
138 features<![%p-not-stable;[, some of them currently under development]]>,
139 that give the end-user more control, more privacy and more freedom:
141 <!-- Include newfeatures.sgml boilerplate here: -->
143 <!-- end boilerplate -->
148 <!-- ~ End section ~ -->
151 <!-- ~~~~~ New section ~~~~~ -->
152 <sect1 id="installation"><title>Installation</title>
155 <application>Privoxy</application> is available both in convenient pre-compiled
156 packages for a wide range of operating systems, and as raw source code.
157 For most users, we recommend using the packages, which can be downloaded from our
158 <ulink url="https://sourceforge.net/projects/ijbswa/">Privoxy Project
164 On some platforms, the installer may remove previously installed versions, if
165 found. (See below for your platform). In any case <emphasis>be sure to backup
166 your old configuration if it is valuable to you.</emphasis> See the <link
167 linkend="upgradersnote">note to upgraders</link> section below.
170 <!-- ~~~~~ New section ~~~~~ -->
171 <sect2 id="installation-packages"><title>Binary Packages</title>
173 How to install the binary packages depends on your operating system:
176 <!-- XXX: The installation sections should be sorted -->
178 <!-- ~~~~~ New section ~~~~~ -->
179 <sect3 id="installation-deb"><title>Debian and Ubuntu</title>
181 DEBs can be installed with <literal>apt-get install privoxy</literal>,
182 and will use <filename>/etc/privoxy</filename> for the location of
187 <!-- ~~~~~ New section ~~~~~ -->
188 <sect3 id="installation-pack-win"><title>Windows</title>
191 Just double-click the installer, which will guide you through
192 the installation process. You will find the configuration files
193 in the same directory as you installed <application>Privoxy</application> in.
196 Version 3.0.5 beta introduced full <application>Windows</application> service
197 functionality. On Windows only, the <application>Privoxy</application>
198 program has two new command line arguments to install and uninstall
199 <application>Privoxy</application> as a <emphasis>service</emphasis>.
203 <term>Arguments:</term>
206 <replaceable class="parameter">--install</replaceable>[:<replaceable class="parameter">service_name</replaceable>]
209 <replaceable class="parameter">--uninstall</replaceable>[:<replaceable class="parameter">service_name</replaceable>]
215 After invoking <application>Privoxy</application> with
216 <command>--install</command>, you will need to bring up the
217 <application>Windows</application> service console to assign the user you
218 want <application>Privoxy</application> to run under, and whether or not you
219 want it to run whenever the system starts. You can start the
220 <application>Windows</application> services console with the following
221 command: <command>services.msc</command>. If you do not take the manual step
222 of modifying <application>Privoxy's</application> service settings, it will
223 not start. Note too that you will need to give Privoxy a user account that
224 actually exists, or it will not be permitted to
225 write to its log and configuration files.
230 <!-- ~~~~~ New section ~~~~~ -->
231 <sect3 id="installation-mac"><title>Mac OS X</title>
233 Installation instructions for the OS X platform depend upon whether
234 you downloaded a ready-built installation package (.pkg or .mpkg) or have
235 downloaded the source code.
238 <sect3 renderas="sect4" id="OS-X-install-from-package">
239 <title>Installation from ready-built package</title>
241 The downloaded file will either be a .pkg (for OS X 10.5 upwards) or a bzipped
242 .mpkg file (for OS X 10.4). The former can be double-clicked as is and the
243 installation will start; double-clicking the latter will unzip the .mpkg file
244 which can then be double-clicked to commence the installation.
247 The privoxy service will automatically start after a successful installation
248 (and thereafter every time your computer starts up) however you will need to
249 configure your web browser(s) to use it. To do so, configure them to use a
250 proxy for HTTP and HTTPS at the address 127.0.0.1:8118.
253 To prevent the privoxy service from automatically starting when your computer
254 starts up, remove or rename the file <literal>/Library/LaunchDaemons/org.ijbswa.privoxy.plist</literal>
255 (on OS X 10.5 and higher) or the folder named
256 <literal>/Library/StartupItems/Privoxy</literal> (on OS X 10.4 'Tiger').
259 To manually start or stop the privoxy service, use the scripts startPrivoxy.sh
260 and stopPrivoxy.sh supplied in /Applications/Privoxy. They must be run from an
261 administrator account, using sudo.
264 To uninstall, run /Applications/Privoxy/uninstall.command as sudo from an
265 administrator account.
268 <sect3 renderas="sect4" id="OS-X-install-from-source">
269 <title>Installation from source</title>
271 To build and install the Privoxy source code on OS X you will need to obtain
272 the macsetup module from the Privoxy Sourceforge CVS repository (refer to
273 Sourceforge help for details of how to set up a CVS client to have read-only
274 access to the repository). This module contains scripts that leverage the usual
275 open-source tools (available as part of Apple's free of charge Xcode
276 distribution or via the usual open-source software package managers for OS X
277 (MacPorts, Homebrew, Fink etc.) to build and then install the privoxy binary
278 and associated files. The macsetup module's README file contains complete
279 instructions for its use.
282 The privoxy service will automatically start after a successful installation
283 (and thereafter every time your computer starts up) however you will need to
284 configure your web browser(s) to use it. To do so, configure them to use a
285 proxy for HTTP and HTTPS at the address 127.0.0.1:8118.
288 To prevent the privoxy service from automatically starting when your computer
289 starts up, remove or rename the file <literal>/Library/LaunchDaemons/org.ijbswa.privoxy.plist</literal>
290 (on OS X 10.5 and higher) or the folder named
291 <literal>/Library/StartupItems/Privoxy</literal> (on OS X 10.4 'Tiger').
294 To manually start or stop the privoxy service, use the Privoxy Utility
295 for Mac OS X (also part of the macsetup module). This application can start
296 and stop the privoxy service and display its log and configuration files.
299 To uninstall, run the macsetup module's uninstall.sh as sudo from an
300 administrator account.
304 <!-- ~~~~~ New section ~~~~~ -->
305 <sect3 id="installation-freebsd"><title>FreeBSD</title>
308 Privoxy is part of FreeBSD's Ports Collection, you can build and install
309 it with <literal>cd /usr/ports/www/privoxy; make install clean</literal>.
315 <!-- ~~~~~ New section ~~~~~ -->
316 <sect2 id="installation-source"><title>Building from Source</title>
319 The most convenient way to obtain the <application>Privoxy</application> source
320 code is to download the source tarball from our
321 <ulink url="https://sourceforge.net/projects/ijbswa/files/Sources/">
322 project download page</ulink>,
323 or you can get the up-to-the-minute, possibly unstable, development version from
324 <ulink url="https://www.privoxy.org/">https://www.privoxy.org/</ulink>.
327 <!-- include buildsource.sgml boilerplate: -->
329 <!-- end boilerplate -->
332 <sect3 id="WINBUILD-CYGWIN"><title>Windows</title>
334 <sect4 id="WINBUILD-SETUP"><title>Setup</title>
336 Install the Cygwin utilities needed to build <application>Privoxy</application>.
337 If you have a 64 bit CPU (which most people do by now), get the
338 Cygwin setup-x86_64.exe program <ulink url="https://cygwin.com/setup-x86_64.exe">here</ulink>
339 (the .sig file is <ulink url="https://cygwin.com/setup-x86_64.exe.sig">here</ulink>).
342 Run the setup program and from View / Category select:
354 mingw64-i686-gcc-core
359 libxslt: GNOME XSLT library (runtime)
375 If you haven't already downloaded the Privoxy source code, get it now:
380 git clone https://www.privoxy.org/git/privoxy.git
384 Get the source code (.zip or .tar.gz) for tidy from
385 <ulink url="https://github.com/htacg/tidy-html5/releases">
386 https://github.com/htacg/tidy-html5/releases</ulink>,
387 unzip into <root-dir> and build the software:
391 cd tidy-html5-x.y.z/build/cmake
392 cmake ../.. -DCMAKE_BUILD_TYPE=Release -DBUILD_SHARED_LIB:BOOL=OFF -DCMAKE_INSTALL_PREFIX=/usr/local
397 If you want to be able to make a Windows release package, get the NSIS .zip file from
398 <!-- FIXME: which version(s) are known to work? -->
399 <ulink url="https://sourceforge.net/projects/nsis/files/NSIS%203/">
400 https://sourceforge.net/projects/nsis/files/NSIS%203/</ulink>
401 and extract the NSIS directory to <literal>privoxy/windows</literal>.
402 Then edit the <filename>windows/GNUmakefile</filename> to set the location
403 of the NSIS executable - eg:
407 MAKENSIS = ./nsis/makensis.exe
412 <sect4 id="WINBUILD-BUILD"><title>Build</title>
415 To build just the Privoxy executable and not the whole installation package, do:
418 cd <root-dir>/privoxy
419 ./windows/MYconfigure && make
423 Privoxy uses the <ulink url="https://en.wikipedia.org/wiki/GNU_build_system">GNU Autotools</ulink>
424 for building software, so the process is:
427 $ autoheader # creates config.h.in
428 $ autoconf # uses config.h.in to create the configure shell script
429 $ ./configure [options] # creates GNUmakefile
430 $ make [options] # builds the program
434 The usual <literal>configure</literal> options for building a native Windows application under cygwin are
437 <literallayout class="Monospaced">
438 --host=i686-w64-mingw32
441 --enable-static-linking
443 --disable-dynamic-pcre
447 You can set the <literal>CFLAGS</literal> and <literal>LDFLAGS</literal> envars before
448 running <literal>configure</literal> to set compiler and linker flags. For example:
452 $ export CFLAGS="-O2" # set gcc optimization level
453 $ export LDFLAGS="-Wl,--nxcompat" # Enable DEP
454 $ ./configure --host=i686-w64-mingw32 --enable-mingw32 --enable-zlib \
455 > --enable-static-linking --disable-pthread --disable-dynamic-pcre
456 $ make # build Privoxy
460 See the <ulink url="../developer-manual/newrelease.html#NEWRELEASE-WINDOWS">Developer's Manual</ulink>
461 for building a Windows release package.
469 <!-- ~~~~~ New section ~~~~~ -->
470 <sect2 id="installation-keepupdated"><title>Keeping your Installation Up-to-Date</title>
473 If you wish to receive an email notification whenever we release updates of
474 <application>Privoxy</application> or the actions file, <ulink
475 url="https://lists.privoxy.org/mailman/listinfo/privoxy-announce">subscribe
476 to our announce mailing list</ulink>, privoxy-announce@lists.privoxy.org.
480 In order not to lose your personal changes and adjustments when updating
481 to the latest <literal>default.action</literal> file we <emphasis>strongly
482 recommend</emphasis> that you use <literal>user.action</literal> and
483 <literal>user.filter</literal> for your local
484 customizations of <application>Privoxy</application>. See the <link
485 linkend="actions-file">Chapter on actions files</link> for details.
493 <!-- ~ End section ~ -->
495 <!-- ~~~~~ New section ~~~~~ -->
496 <sect1 id="whatsnew">
497 <title>What's New in this Release</title>
501 <!-- ~~~~~ New section ~~~~~ -->
503 <sect2 id="upgradersnote">
504 <title>Note to Upgraders</title>
507 A quick list of things to be aware of before upgrading from earlier
508 versions of <application>Privoxy</application>:
515 The recommended way to upgrade &my-app; is to backup your old
516 configuration files, install the new ones, verify that &my-app;
517 is working correctly and finally merge back your changes using
518 <application>diff</application> and maybe <application>patch</application>.
521 There are a number of new features in each &my-app; release and
522 most of them have to be explicitly enabled in the configuration
523 files. Old configuration files obviously don't do that and due
524 to syntax changes using old configuration files with a new
525 &my-app; isn't always possible anyway.
530 Note that some installers remove earlier versions completely,
531 including configuration files, therefore you should really save
532 any important configuration files!
537 On the other hand, other installers don't overwrite existing configuration
538 files, thinking you will want to do that yourself.
543 In the default configuration only fatal errors are logged now.
544 You can change that in the <link linkend="DEBUG">debug section</link>
545 of the configuration file. You may also want to enable more verbose
546 logging until you verified that the new &my-app; version is working
553 Three other config file settings are now off by default:
554 <link linkend="enable-remote-toggle">enable-remote-toggle</link>,
555 <link linkend="enable-remote-http-toggle">enable-remote-http-toggle</link>,
556 and <link linkend="enable-edit-actions">enable-edit-actions</link>.
557 If you use or want these, you will need to explicitly enable them, and
558 be aware of the security issues involved.
565 What constitutes a <quote>default</quote> configuration has changed,
566 and you may want to review which actions are <quote>on</quote> by
567 default. This is primarily a matter of emphasis, but some features
568 you may have been used to, may now be <quote>off</quote> by default.
569 There are also a number of new actions and filters you may want to
570 consider, most of which are not fully incorporated into the default
571 settings as yet (see above).
578 The default actions setting is now <literal>Cautious</literal>. Previous
579 releases had a default setting of <literal>Medium</literal>. Experienced
580 users may want to adjust this, as it is fairly conservative by &my-app;
581 standards and past practices. See <ulink
582 url="http://config.privoxy.org/edit-actions-list?f=default">
583 http://config.privoxy.org/edit-actions-list?f=default</ulink>. New users
584 should try the default settings for a while before turning up the volume.
590 The default setting has filtering turned <emphasis>off</emphasis>, which
591 subsequently means that compression is <emphasis>on</emphasis>. Remember
592 that filtering does not work on compressed pages, so if you use, or want to
593 use, filtering, you will need to force compression off. Example:
596 { +<link linkend="filter">filter</link>{google} +<link linkend="prevent-compression">prevent-compression</link> }
599 Or if you use a number of filters, or filter many sites, you may just want
600 to turn off compression for all sites in
601 <filename>default.action</filename> (or
602 <filename>user.action</filename>).
609 Also, <link linkend="SESSION-COOKIES-ONLY">session-cookies-only</link> is
610 off by default now. If you've liked this feature in the past, you may want
611 to turn it back on in <filename>user.action</filename> now.
618 Some installers may not automatically start
619 <application>Privoxy</application> after installation.
629 <!-- ~~~~~ New section ~~~~~ -->
630 <sect1 id="quickstart"><title>Quickstart to Using Privoxy</title>
636 Install <application>Privoxy</application>. See the <link
637 linkend="installation">Installation Section</link> below for platform specific
644 Advanced users and those who want to offer <application>Privoxy</application>
645 service to more than just their local machine should check the <link
646 linkend="config">main config file</link>, especially the <link
647 linkend="access-control">security-relevant</link> options. These are
654 Start <application>Privoxy</application>, if the installation program has
655 not done this already (may vary according to platform). See the section
656 <link linkend="startup">Starting <application>Privoxy</application></link>.
662 Set your browser to use <application>Privoxy</application> as HTTP and
663 HTTPS (SSL) <ulink url="https://en.wikipedia.org/wiki/Proxy_server">proxy</ulink>
664 by setting the proxy configuration for address of
665 <literal>127.0.0.1</literal> and port <literal>8118</literal>.
666 <emphasis>DO NOT</emphasis> activate proxying for <literal>FTP</literal> or
667 any protocols besides HTTP and HTTPS (SSL) unless you intend to prevent your
668 browser from using these protocols.
674 Flush your browser's disk and memory caches, to remove any cached ad images.
675 If using <application>Privoxy</application> to manage
676 <ulink url="https://en.wikipedia.org/wiki/Browser_cookie">cookies</ulink>,
677 you should remove any currently stored cookies too.
683 A default installation should provide a reasonable starting point for
684 most. There will undoubtedly be occasions where you will want to adjust the
685 configuration, but that can be dealt with as the need arises. Little
686 to no initial configuration is required in most cases, you may want
688 <ulink url="config.html#ENABLE-EDIT-ACTIONS">web-based action editor</ulink> though.
689 Be sure to read the warnings first.
692 See the <link linkend="configuration">Configuration section</link> for more
693 configuration options, and how to customize your installation.
694 You might also want to look at the <link
695 linkend="quickstart-ad-blocking">next section</link> for a quick
696 introduction to how <application>Privoxy</application> blocks ads and
703 If you experience ads that slip through, innocent images that are
704 blocked, or otherwise feel the need to fine-tune
705 <application>Privoxy's</application> behavior, take a look at the <link
706 linkend="actions-file">actions files</link>. As a quick start, you might
707 find the <link linkend="act-examples">richly commented examples</link>
708 helpful. You can also view and edit the actions files through the <ulink
709 url="http://config.privoxy.org">web-based user interface</ulink>. The
710 Appendix <quote><link linkend="actionsanat">Troubleshooting: Anatomy of an
711 Action</link></quote> has hints on how to understand and debug actions that
712 <quote>misbehave</quote>.
718 Please see the section <link linkend="contact">Contacting the
719 Developers</link> on how to report bugs, problems with websites or to get
726 Now enjoy surfing with enhanced control, comfort and privacy!
733 <!-- ~~~~~ New section ~~~~~ -->
735 <sect2 id="quickstart-ad-blocking">
736 <title>Quickstart to Ad Blocking</title>
738 NOTE: This section is deliberately redundant for those that don't
739 want to read the whole thing (which is getting lengthy).
742 Ad blocking is but one of <application>Privoxy's</application>
743 array of features. Many of these features are for the technically minded advanced
744 user. But, ad and banner blocking is surely common ground for everybody.
747 This section will provide a quick summary of ad blocking so
748 you can get up to speed quickly without having to read the more extensive
749 information provided below, though this is highly recommended.
752 First a bit of a warning ... blocking ads is much like blocking SPAM: the
753 more aggressive you are about it, the more likely you are to block
754 things that were not intended. And the more likely that some things
755 may not work as intended. So there is a trade off here. If you want
756 extreme ad free browsing, be prepared to deal with more
757 <quote>problem</quote> sites, and to spend more time adjusting the
758 configuration to solve these unintended consequences. In short, there is
759 not an easy way to eliminate <emphasis>all</emphasis> ads. Either take
760 the easy way and settle for <emphasis>most</emphasis> ads blocked with the
761 default configuration, or jump in and tweak it for your personal surfing
762 habits and preferences.
765 Secondly, a brief explanation of <application>Privoxy's </application>
766 <quote>actions</quote>. <quote>Actions</quote> in this context, are
767 the directives we use to tell <application>Privoxy</application> to perform
768 some task relating to HTTP transactions (i.e. web browsing). We tell
769 <application>Privoxy</application> to take some <quote>action</quote>. Each
770 action has a unique name and function. While there are many potential
771 <application>actions</application> in <application>Privoxy's</application>
772 arsenal, only a few are used for ad blocking. <link
773 linkend="actions">Actions</link>, and <link linkend="actions-file">action
774 configuration files</link>, are explained in depth below.
777 Actions are specified in <application>Privoxy's</application> configuration,
778 followed by one or more URLs to which the action should apply. URLs
779 can actually be URL type <link linkend="af-patterns">patterns</link> that use
780 wildcards so they can apply potentially to a range of similar URLs. The
781 actions, together with the URL patterns are called a section.
784 When you connect to a website, the full URL will either match one or more
785 of the sections as defined in <application>Privoxy's</application> configuration,
786 or not. If so, then <application>Privoxy</application> will perform the
787 respective actions. If not, then nothing special happens. Furthermore, web
788 pages may contain embedded, secondary URLs that your web browser will
789 use to load additional components of the page, as it parses the
790 original page's HTML content. An ad image for instance, is just an URL
791 embedded in the page somewhere. The image itself may be on the same server,
792 or a server somewhere else on the Internet. Complex web pages will have many
793 such embedded URLs. &my-app; can deal with each URL individually, so, for
794 instance, the main page text is not touched, but images from such-and-such
799 The most important actions for basic ad blocking are: <literal><link
800 linkend="block">block</link></literal>, <literal><link
801 linkend="handle-as-image">handle-as-image</link></literal>,
803 linkend="handle-as-empty-document">handle-as-empty-document</link></literal>,and
804 <literal><link linkend="set-image-blocker">set-image-blocker</link></literal>:
811 <literal><link linkend="block">block</link></literal> - this is perhaps
812 the single most used action, and is particularly important for ad blocking.
813 This action stops any contact between your browser and any URL patterns
814 that match this action's configuration. It can be used for blocking ads,
815 but also anything that is determined to be unwanted. By itself, it simply
816 stops any communication with the remote server and sends
817 <application>Privoxy</application>'s own built-in BLOCKED page instead to
818 let you now what has happened (with some exceptions, see below).
824 <literal><link linkend="handle-as-image">handle-as-image</link></literal> -
825 tells <application>Privoxy</application> to treat this URL as an image.
826 <application>Privoxy</application>'s default configuration already does this
827 for all common image types (e.g. GIF), but there are many situations where this
828 is not so easy to determine. So we'll force it in these cases. This is particularly
829 important for ad blocking, since only if we know that it's an image of
830 some kind, can we replace it with an image of our choosing, instead of the
831 <application>Privoxy</application> BLOCKED page (which would only result in
832 a <quote>broken image</quote> icon). There are some limitations to this
833 though. For instance, you can't just brute-force an image substitution for
834 an entire HTML page in most situations.
840 <literal><link linkend="handle-as-empty-document">handle-as-empty-document</link></literal> -
841 sends an empty document instead of <application>Privoxy's</application>
842 normal BLOCKED HTML page. This is useful for file types that are neither
843 HTML nor images, such as blocking JavaScript files.
850 linkend="set-image-blocker">set-image-blocker</link></literal> - tells
851 <application>Privoxy</application> what to display in place of an ad image that
852 has hit a block rule. For this to come into play, the URL must match a
853 <literal><link linkend="block">block</link></literal> action somewhere in the
854 configuration, <emphasis>and</emphasis>, it must also match an
855 <literal><link linkend="handle-as-image">handle-as-image</link></literal> action.
858 The configuration options on what to display instead of the ad are:
862 <emphasis>pattern</emphasis> - a checkerboard pattern, so that an ad
863 replacement is obvious. This is the default.
868 <emphasis>blank</emphasis> - A very small empty GIF image is displayed.
869 This is the so-called <quote>invisible</quote> configuration option.
874 <emphasis>http://<URL></emphasis> - A redirect to any image anywhere
875 of the user's choosing (advanced usage).
883 Advanced users will eventually want to explore &my-app;
884 <literal><link linkend="filter">filters</link></literal> as well. Filters
885 are very different from <literal><link
886 linkend="block">blocks</link></literal>.
887 A <quote>block</quote> blocks a site, page, or unwanted contented. Filters
888 are a way of filtering or modifying what is actually on the page. An example
889 filter usage: a text replacement of <quote>no-no</quote> for
890 <quote>nasty-word</quote>. That is a very simple example. This process can be
891 used for ad blocking, but it is more in the realm of advanced usage and has
892 some pitfalls to be wary off.
896 The quickest way to adjust any of these settings is with your browser through
897 the special <application>Privoxy</application> editor at <ulink
898 url="http://config.privoxy.org/show-status">http://config.privoxy.org/show-status</ulink>
899 (shortcut: <ulink url="http://p.p/">http://p.p/show-status</ulink>). This
900 is an internal page, and does not require Internet access.
904 Note that as of <application>Privoxy</application> 3.0.7 beta the
905 action editor is disabled by default. Check the
906 <ulink url="config.html#ENABLE-EDIT-ACTIONS">enable-edit-actions
907 section in the configuration file</ulink> to learn why and in which
908 cases it's safe to enable again.
912 If you decided to enable the action editor, select the appropriate
913 <quote>actions</quote> file, and click
914 <quote><guibutton>Edit</guibutton></quote>. It is best to put personal or
915 local preferences in <filename>user.action</filename> since this is not
916 meant to be overwritten during upgrades, and will over-ride the settings in
917 other files. Here you can insert new <quote>actions</quote>, and URLs for ad
918 blocking or other purposes, and make other adjustments to the configuration.
919 <application>Privoxy</application> will detect these changes automatically.
923 A quick and simple step by step example:
930 Right click on the ad image to be blocked, then select
931 <quote><guimenuitem>Copy Link Location</guimenuitem></quote> from the
939 url="http://config.privoxy.org/show-status">http://config.privoxy.org/show-status</ulink>
944 Find <filename>user.action</filename> in the top section, and click
945 on <quote><guibutton>Edit</guibutton></quote>:
948 <!-- image of editor and actions files selections -->
949 <figure pgwide="0" float="0"><title>Actions Files in Use</title>
952 <imagedata fileref="files-in-use.jpg" format="jpg">
955 <phrase>[ Screenshot of Actions Files in Use ]</phrase>
963 You should have a section with only
964 <literal><link linkend="block">block</link></literal> listed under
965 <quote>Actions:</quote>.
966 If not, click a <quote><guibutton>Insert new section below</guibutton></quote>
967 button, and in the new section that just appeared, click the
968 <guibutton>Edit</guibutton> button right under the word <quote>Actions:</quote>.
969 This will bring up a list of all actions. Find
970 <literal><link linkend="block">block</link></literal> near the top, and click
971 in the <quote>Enabled</quote> column, then <quote><guibutton>Submit</guibutton></quote>
977 Now, in the <literal><link linkend="block">block</link></literal> actions section,
978 click the <quote><guibutton>Add</guibutton></quote> button, and paste the URL the
979 browser got from <quote><guimenuitem>Copy Link Location</guimenuitem></quote>.
980 Remove the <literal>http://</literal> at the beginning of the URL. Then, click
981 <quote><guibutton>Submit</guibutton></quote> (or
982 <quote><guibutton>OK</guibutton></quote> if in a pop-up window).
987 Now go back to the original page, and press <keycap>SHIFT-Reload</keycap>
988 (or flush all browser caches). The image should be gone now.
995 This is a very crude and simple example. There might be good reasons to use a
996 wildcard pattern match to include potentially similar images from the same
997 site. For a more extensive explanation of <quote>patterns</quote>, and
998 the entire actions concept, see <link linkend="actions-file">the Actions
1003 For advanced users who want to hand edit their config files, you might want
1004 to now go to the <link linkend="act-examples">Actions Files Tutorial</link>.
1005 The ideas explained therein also apply to the web-based editor.
1008 There are also various
1009 <link linkend="filter">filters</link> that can be used for ad blocking
1010 (filters are a special subset of actions). These
1011 fall into the <quote>advanced</quote> usage category, and are explained in
1012 depth in later sections.
1019 <!-- ~ End section ~ -->
1022 <!-- ~~~~~ New section ~~~~~ -->
1023 <sect1 id="startup">
1024 <title>Starting Privoxy</title>
1026 Before launching <application>Privoxy</application> for the first time, you
1027 will want to configure your browser(s) to use
1028 <application>Privoxy</application> as a HTTP and HTTPS (SSL)
1029 <ulink url="https://en.wikipedia.org/wiki/Proxy_server">proxy</ulink>. The default is
1030 127.0.0.1 (or localhost) for the proxy address, and port 8118 (earlier versions
1031 used port 8000). This is the one configuration step <emphasis>that must be done
1035 Please note that <application>Privoxy</application> can only proxy HTTP and
1036 HTTPS traffic. It will not work with FTP or other protocols.
1039 <!-- image of Mozilla Proxy configuration -->
1040 <figure pgwide="0" float="0"><title>Proxy Configuration Showing
1041 Mozilla Firefox HTTP and HTTPS (SSL) Settings</title>
1044 <imagedata fileref="proxy_setup.jpg" format="jpg">
1047 <phrase>[ Screenshot of Mozilla Firefox Proxy Configuration ]</phrase>
1054 With <application>Firefox</application>, this is typically set under:
1058 <guibutton>Edit</guibutton> -> <guibutton>Preferences</guibutton> -> <guibutton>Network Settings</guibutton> -> <guibutton>Settings</guibutton>
1062 Or optionally on some platforms:
1066 <guibutton>Edit</guibutton> -> <guibutton>Preferences</guibutton> -> <guibutton>General</guibutton> -> <guibutton>Connection Settings</guibutton> -> <guibutton>Manual Proxy Configuration</guibutton>
1071 With <application>Netscape</application> (and
1072 <application>Mozilla</application>), this can be set under:
1077 <!-- Mix ascii and gui art, something for everybody -->
1078 <!-- spacing on this is tricky -->
1079 <guibutton>Edit</guibutton> -> <guibutton>Preferences</guibutton> -> <guibutton>Advanced</guibutton> -> <guibutton>Proxies</guibutton> -> <guibutton>HTTP Proxy</guibutton>
1083 For <application>Internet Explorer v.5-7</application>:
1087 <guibutton>Tools</guibutton> -> <guibutton>Internet Options</guibutton> -> <guibutton>Connections</guibutton> -> <guibutton>LAN Settings</guibutton>
1091 Then, check <quote>Use Proxy</quote> and fill in the appropriate info
1092 (Address: 127.0.0.1, Port: 8118). Include HTTPS (SSL), if you want HTTPS
1093 proxy support too (sometimes labeled <quote>Secure</quote>). Make sure any
1094 checkboxes like <quote>Use the same proxy server for all protocols</quote> is
1095 <emphasis>UNCHECKED</emphasis>. You want only HTTP and HTTPS (SSL)!
1098 <!-- image of IE Proxy configuration -->
1099 <figure pgwide="0" float="0"><title>Proxy Configuration Showing
1100 Internet Explorer HTTP and HTTPS (Secure) Settings</title>
1103 <imagedata fileref="proxy2.jpg" format="jpg">
1106 <phrase>[ Screenshot of IE Proxy Configuration ]</phrase>
1113 After doing this, flush your browser's disk and memory caches to force a
1114 re-reading of all pages and to get rid of any ads that may be cached. Remove
1115 any <ulink url="https://en.wikipedia.org/wiki/Browser_cookie">cookies</ulink>,
1116 if you want <application>Privoxy</application> to manage that. You are now
1117 ready to start enjoying the benefits of using
1118 <application>Privoxy</application>!
1122 <application>Privoxy</application> itself is typically started by specifying the
1123 main configuration file to be used on the command line. If no configuration
1124 file is specified on the command line, <application>Privoxy</application>
1125 will look for a file named <filename>config</filename> in the current
1126 directory. Except on Win32 where it will try <filename>config.txt</filename>.
1129 <sect2 id="start-debian">
1130 <title>Debian</title>
1132 We use a script. Note that Debian typically starts &my-app; upon booting per
1133 default. It will use the file
1134 <filename>/etc/privoxy/config</filename> as its main configuration
1138 # /etc/init.d/privoxy start
1142 <sect2 id="start-freebsd">
1143 <title>FreeBSD and ElectroBSD</title>
1145 To start <application>Privoxy</application> upon booting, add
1146 "privoxy_enable='YES'" to <filename>/etc/rc.conf</filename>.
1147 <application>Privoxy</application> will use
1148 <filename>/usr/local/etc/privoxy/config</filename> as its main
1152 If you installed <application>Privoxy</application> into a jail, the
1153 paths above are relative to the jail root.
1156 To start <application>Privoxy</application> manually, run:
1159 # service privoxy onestart
1163 <sect2 id="start-windows">
1164 <title>Windows</title>
1166 Click on the &my-app; Icon to start <application>Privoxy</application>. If no configuration file is
1167 specified on the command line, <application>Privoxy</application> will look
1168 for a file named <filename>config.txt</filename>. Note that Windows will
1169 automatically start &my-app; when the system starts if you chose that option
1173 <application>Privoxy</application> can run with full Windows service functionality.
1174 On Windows only, the &my-app; program has two new command line arguments
1175 to install and uninstall &my-app; as a service. See the
1176 <link linkend="installation-pack-win">Windows Installation
1177 instructions</link> for details.
1181 <sect2 id="start-unices">
1182 <title>Generic instructions for Unix derivates (Solaris, NetBSD, HP-UX etc.)</title>
1184 Example Unix startup command:
1187 # /usr/sbin/privoxy --user privoxy /etc/privoxy/config
1190 Note that if you installed <application>Privoxy</application> through
1191 a package manager, the package will probably contain a platform-specific
1192 script or configuration file to start <application>Privoxy</application>
1197 <sect2 id="start-macosx">
1198 <title>Mac OS X</title>
1200 The privoxy service will automatically start after a successful installation
1201 (and thereafter every time your computer starts up) however you will need to
1202 configure your web browser(s) to use it. To do so, configure them to use a
1203 proxy for HTTP and HTTPS at the address 127.0.0.1:8118.
1206 To prevent the privoxy service from automatically starting when your computer
1207 starts up, remove or rename the file <literal>/Library/LaunchDaemons/org.ijbswa.privoxy.plist</literal>
1208 (on OS X 10.5 and higher) or the folder named
1209 <literal>/Library/StartupItems/Privoxy</literal> (on OS X 10.4 'Tiger').
1212 To manually start or stop the privoxy service, use the scripts startPrivoxy.sh
1213 and stopPrivoxy.sh supplied in /Applications/Privoxy. They must be run from an
1214 administrator account, using sudo.
1222 See the section <link linkend="cmdoptions">Command line options</link> for
1226 must find a better place for this paragraph
1229 The included default configuration files should give a reasonable starting
1230 point. Most of the per site configuration is done in the
1231 <ulink url="actions-file.html"><quote>actions</quote></ulink> files. These are
1232 where various cookie actions are defined, ad and banner blocking, and other
1233 aspects of <application>Privoxy</application> configuration. There are several
1234 such files included, with varying levels of aggressiveness.
1238 You will probably want to keep an eye out for sites for which you may prefer
1239 persistent cookies, and add these to your actions configuration as needed. By
1240 default, most of these will be accepted only during the current browser
1241 session (aka <quote>session cookies</quote>), unless you add them to the
1242 configuration. If you want the browser to handle this instead, you will need
1243 to edit <filename>user.action</filename> (or through the web based interface)
1244 and disable this feature. If you use more than one browser, it would make
1245 more sense to let <application>Privoxy</application> handle this. In which
1246 case, the browser(s) should be set to accept all cookies.
1250 Another feature where you will probably want to define exceptions for trusted
1251 sites is the popup-killing (through <ulink
1252 url="actions-file.html#FILTER-POPUPS"><quote>+filter{popups}</quote></ulink>),
1253 because your favorite shopping, banking, or leisure site may need
1254 popups (explained below).
1258 <application>Privoxy</application> does not support all of the optional HTTP/1.1
1259 features yet. In the unlikely event that you experience inexplicable problems
1260 with browsers that use HTTP/1.1 per default
1261 (like <application>Mozilla</application> or recent versions of I.E.), you might
1262 try to force HTTP/1.0 compatibility. For Mozilla, look under <literal>Edit ->
1263 Preferences -> Debug -> Networking</literal>.
1264 Alternatively, set the <quote>+downgrade-http-version</quote> config option in
1265 <filename>default.action</filename> which will downgrade your browser's HTTP
1266 requests from HTTP/1.1 to HTTP/1.0 before processing them.
1270 After running <application>Privoxy</application> for a while, you can
1271 start to fine tune the configuration to suit your personal, or site,
1272 preferences and requirements. There are many, many aspects that can
1273 be customized. <quote>Actions</quote>
1274 can be adjusted by pointing your browser to
1275 <ulink url="http://config.privoxy.org/">http://config.privoxy.org/</ulink>
1276 (shortcut: <ulink url="http://p.p/">http://p.p/</ulink>),
1277 and then follow the link to <quote>View & Change the Current Configuration</quote>.
1278 (This is an internal page and does not require Internet access.)
1282 In fact, various aspects of <application>Privoxy</application>
1283 configuration can be viewed from this page, including
1284 current configuration parameters, source code version numbers,
1285 the browser's request headers, and <quote>actions</quote> that apply
1286 to a given URL. In addition to the actions file
1287 editor mentioned above, <application>Privoxy</application> can also
1288 be turned <quote>on</quote> and <quote>off</quote> (toggled) from this page.
1292 If you encounter problems, try loading the page without
1293 <application>Privoxy</application>. If that helps, enter the URL where
1294 you have the problems into <ulink url="http://p.p/show-url-info">the browser
1295 based rule tracing utility</ulink>. See which rules apply and why, and
1296 then try turning them off for that site one after the other, until the problem
1297 is gone. When you have found the culprit, you might want to turn the rest on
1302 If the above paragraph sounds gibberish to you, you might want to <link
1303 linkend="actions-file">read more about the actions concept</link>
1304 or even dive deep into the <link linkend="actionsanat">Appendix
1309 If you can't get rid of the problem at all, think you've found a bug in
1310 Privoxy, want to propose a new feature or smarter rules, please see the
1311 section <link linkend="contact"><quote>Contacting the
1312 Developers</quote></link> below.
1317 <!-- ~~~~~ New section ~~~~~ -->
1318 <sect2 id="cmdoptions">
1319 <title>Command Line Options</title>
1321 <application>Privoxy</application> may be invoked with the following
1322 command-line options:
1329 <emphasis>--config-test</emphasis>
1332 Exit after loading the configuration files before binding to
1333 the listen address. The exit code signals whether or not the
1334 configuration files have been successfully loaded.
1337 If the exit code is 1, at least one of the configuration files
1338 is invalid, if it is 0, all the configuration files have been
1339 successfully loaded (but may still contain errors that can
1340 currently only be detected at run time).
1343 This option doesn't affect the log setting, combination with
1344 <emphasis>--no-daemon</emphasis> is recommended if a configured
1345 log file shouldn't be used.
1350 <emphasis>--version</emphasis>
1353 Print version info and exit. Unix only.
1358 <emphasis>--help</emphasis>
1361 Print short usage info and exit. Unix only.
1366 <emphasis>--no-daemon</emphasis>
1369 Don't become a daemon, i.e. don't fork and become process group
1370 leader, and don't detach from controlling tty. Unix only.
1375 <emphasis>--pidfile FILE</emphasis>
1378 On startup, write the process ID to <emphasis>FILE</emphasis>. Delete the
1379 <emphasis>FILE</emphasis> on exit. Failure to create or delete the
1380 <emphasis>FILE</emphasis> is non-fatal. If no <emphasis>FILE</emphasis>
1381 option is given, no PID file will be used. Unix only.
1386 <emphasis>--user USER[.GROUP]</emphasis>
1389 After (optionally) writing the PID file, assume the user ID of
1390 <emphasis>USER</emphasis>, and if included the GID of GROUP. Exit if the
1391 privileges are not sufficient to do so. Unix only.
1396 <emphasis>--chroot</emphasis>
1399 Before changing to the user ID given in the <emphasis>--user</emphasis> option,
1400 chroot to that user's home directory, i.e. make the kernel pretend to the &my-app;
1401 process that the directory tree starts there. If set up carefully, this can limit
1402 the impact of possible vulnerabilities in &my-app; to the files contained in that hierarchy.
1408 <emphasis>--pre-chroot-nslookup hostname</emphasis>
1411 Specifies a hostname (for example www.privoxy.org) to look up before doing a chroot.
1412 On some systems, initializing the resolver library involves reading config files from
1413 /etc and/or loading additional shared libraries from /lib.
1414 On these systems, doing a hostname lookup before the chroot reduces
1415 the number of files that must be copied into the chroot tree.
1418 For fastest startup speed, a good value is a hostname that is not in /etc/hosts but that
1419 your local name server (listed in /etc/resolv.conf) can resolve without recursion
1420 (that is, without having to ask any other name servers). The hostname need not exist,
1421 but if it doesn't, an error message (which can be ignored) will be output.
1427 <emphasis>configfile</emphasis>
1430 If no <emphasis>configfile</emphasis> is included on the command line,
1431 <application>Privoxy</application> will look for a file named
1432 <quote>config</quote> in the current directory (except on Win32
1433 where it will look for <quote>config.txt</quote> instead). Specify
1434 full path to avoid confusion. If no config file is found,
1435 <application>Privoxy</application> will fail to start.
1442 On <application>MS Windows</application> only there are two additional
1443 command-line options to allow <application>Privoxy</application> to install and
1444 run as a <emphasis>service</emphasis>. See the
1445 <link linkend="installation-pack-win">Window Installation section</link>
1453 <!-- ~ End section ~ -->
1456 <!-- ~~~~~ New section ~~~~~ -->
1457 <sect1 id="configuration"><title>Privoxy Configuration</title>
1459 All <application>Privoxy</application> configuration is stored
1460 in text files. These files can be edited with a text editor.
1461 Many important aspects of <application>Privoxy</application> can
1462 also be controlled easily with a web browser.
1466 <!-- ~~~~~ New section ~~~~~ -->
1468 <sect2 id="control-with-webbrowser">
1469 <title>Controlling Privoxy with Your Web Browser</title>
1471 <application>Privoxy</application>'s user interface can be reached through the special
1472 URL <ulink url="http://config.privoxy.org/">http://config.privoxy.org/</ulink>
1473 (shortcut: <ulink url="http://p.p/">http://p.p/</ulink>),
1474 which is a built-in page and works without Internet access.
1475 You will see the following section:
1478 <!-- Needs to be put in a table and colorized -->
1479 <screen><!-- want the background color that goes with screen -->
1481 <bridgehead renderas="sect2"> Privoxy Menu</bridgehead>
1484 ▪ <ulink url="http://config.privoxy.org/show-status">View & change the current configuration</ulink>
1487 ▪ <ulink url="http://config.privoxy.org/client-tags">View or toggle the tags that can be set based on the client's address</ulink>
1490 ▪ <ulink url="http://config.privoxy.org/show-request">View the request headers.</ulink>
1493 ▪ <ulink url="http://config.privoxy.org/show-url-info">Look up which actions apply to a URL and why</ulink>
1496 ▪ <ulink url="http://config.privoxy.org/toggle">Toggle Privoxy on or off</ulink>
1499 ▪ <ulink
1500 url="https://www.privoxy.org/&p-version;/user-manual/">Documentation</ulink>
1508 This should be self-explanatory. Note the first item leads to an editor for the
1509 <link linkend="actions-file">actions files</link>, which is where the ad, banner,
1510 cookie, and URL blocking magic is configured as well as other advanced features of
1511 <application>Privoxy</application>. This is an easy way to adjust various
1512 aspects of <application>Privoxy</application> configuration. The actions
1513 file, and other configuration files, are explained in detail below.
1517 <quote>Toggle Privoxy On or Off</quote> is handy for sites that might
1518 have problems with your current actions and filters. You can in fact use
1519 it as a test to see whether it is <application>Privoxy</application>
1520 causing the problem or not. <application>Privoxy</application> continues
1521 to run as a proxy in this case, but all manipulation is disabled, i.e.
1522 <application>Privoxy</application> acts like a normal forwarding proxy.
1526 Note that several of the features described above are disabled by default
1527 in <application>Privoxy</application> 3.0.7 beta and later.
1529 <ulink url="config.html">configuration file</ulink> to learn why
1530 and in which cases it's safe to enable them again.
1535 <!-- ~ End section ~ -->
1540 <!-- ~~~~~ New section ~~~~~ -->
1542 <sect2 id="confoverview">
1543 <title>Configuration Files Overview</title>
1545 For Unix, *BSD and GNU/Linux, all configuration files are located in
1546 <filename>/etc/privoxy/</filename> by default. For MS Windows
1547 these are all in the same directory as the
1548 <application>Privoxy</application> executable. <![%p-not-stable;[ The name
1549 and number of configuration files has changed from previous versions, and is
1550 subject to change as development progresses.]]>
1554 The installed defaults provide a reasonable starting point, though
1555 some settings may be aggressive by some standards. For the time being, the
1556 principle configuration files are:
1563 The <link linkend="config">main configuration file</link> is named <filename>config</filename>
1564 on GNU/Linux, Unix, BSD, and <filename>config.txt</filename>
1565 on Windows. This is a required file.
1571 <filename>match-all.action</filename> is used to define which <quote>actions</quote>
1572 relating to banner-blocking, images, pop-ups, content modification, cookie handling
1573 etc should be applied by default. It should be the first actions file loaded.
1576 <filename>default.action</filename> defines many exceptions (both positive and negative)
1577 from the default set of actions that's configured in <filename>match-all.action</filename>.
1578 It should be the second actions file loaded and shouldn't be edited by the user.
1581 Multiple actions files may be defined in <filename>config</filename>. These
1582 are processed in the order they are defined. Local customizations and locally
1583 preferred exceptions to the default policies as defined in
1584 <filename>match-all.action</filename> (which you will most probably want
1585 to define sooner or later) are best applied in <filename>user.action</filename>,
1586 where you can preserve them across upgrades. The file isn't installed by all
1587 installers, but you can easily create it yourself with a text editor.
1590 There is also a web based editor that can be accessed from
1592 url="http://config.privoxy.org/show-status">http://config.privoxy.org/show-status</ulink>
1594 url="http://p.p/show-status">http://p.p/show-status</ulink>) for the
1595 various actions files.
1601 <quote>Filter files</quote> (the <link linkend="filter-file">filter
1602 file</link>) can be used to re-write the raw page content, including
1603 viewable text as well as embedded HTML and JavaScript, and whatever else
1604 lurks on any given web page. The filtering jobs are only pre-defined here;
1605 whether to apply them or not is up to the actions files.
1606 <filename>default.filter</filename> includes various filters made
1607 available for use by the developers. Some are much more intrusive than
1608 others, and all should be used with caution. You may define additional
1609 filter files in <filename>config</filename> as you can with
1610 actions files. We suggest <filename>user.filter</filename> for any
1611 locally defined filters or customizations.
1618 The syntax of the configuration and filter files may change between different
1619 Privoxy versions, unfortunately some enhancements cost backwards compatibility.
1620 <!-- Add link to documentation-->
1624 All files use the <quote><literal>#</literal></quote> character to denote a
1625 comment (the rest of the line will be ignored) and understand line continuation
1626 through placing a backslash ("<literal>\</literal>") as the very last character
1627 in a line. If the <literal>#</literal> is preceded by a backslash, it looses
1628 its special function. Placing a <literal>#</literal> in front of an otherwise
1629 valid configuration line to prevent it from being interpreted is called "commenting
1630 out" that line. Blank lines are ignored.
1634 The actions files and filter files
1635 can use Perl style <link linkend="regex">regular expressions</link> for
1636 maximum flexibility.
1640 After making any changes, there is no need to restart
1641 <application>Privoxy</application> in order for the changes to take
1642 effect. <application>Privoxy</application> detects such changes
1643 automatically. Note, however, that it may take one or two additional
1644 requests for the change to take effect. When changing the listening address
1645 of <application>Privoxy</application>, these <quote>wake up</quote> requests
1646 must obviously be sent to the <emphasis>old</emphasis> listening address.
1651 While under development, the configuration content is subject to change.
1652 The below documentation may not be accurate by the time you read this.
1653 Also, what constitutes a <quote>default</quote> setting, may change, so
1654 please check all your configuration files on important issues.
1660 <!-- ~ End section ~ -->
1663 <!-- ~~~~~~~~ New section Header ~~~~~~~~~ -->
1665 <!-- **************************************************** -->
1666 <!-- Include config.sgml here -->
1667 <!-- This is where the entire config file is detailed. -->
1669 <!-- end include -->
1672 <!-- ~ End section ~ -->
1676 <!-- ~~~~~~~~ New section Header ~~~~~~~~~ -->
1678 <sect1 id="actions-file"><title>Actions Files</title>
1682 XXX: similar descriptions are in the Configuration Files sections.
1683 We should only describe them at one place.
1686 The actions files are used to define what <emphasis>actions</emphasis>
1687 <application>Privoxy</application> takes for which URLs, and thus determines
1688 how ad images, cookies and various other aspects of HTTP content and
1689 transactions are handled, and on which sites (or even parts thereof).
1690 There are a number of such actions, with a wide range of functionality.
1691 Each action does something a little different.
1692 These actions give us a veritable arsenal of tools with which to exert
1693 our control, preferences and independence. Actions can be combined so that
1694 their effects are aggregated when applied against a given set of URLs.
1698 are three action files included with <application>Privoxy</application> with
1704 <filename>match-all.action</filename> - is used to define which
1705 <quote>actions</quote> relating to banner-blocking, images, pop-ups,
1706 content modification, cookie handling etc should be applied by default.
1707 It should be the first actions file loaded
1712 <filename>default.action</filename> - defines many exceptions (both
1713 positive and negative) from the default set of actions that's configured
1714 in <filename>match-all.action</filename>. It is a set of rules that should
1715 work reasonably well as-is for most users. This file is only supposed to
1716 be edited by the developers. It should be the second actions file loaded.
1721 <filename>user.action</filename> - is intended to be for local site
1722 preferences and exceptions. As an example, if your ISP or your bank
1723 has specific requirements, and need special handling, this kind of
1724 thing should go here. This file will not be upgraded.
1729 <guibutton>Edit</guibutton> <guibutton>Set to Cautious</guibutton> <guibutton>Set to Medium</guibutton> <guibutton>Set to Advanced</guibutton>
1732 These have increasing levels of aggressiveness <emphasis>and have no
1733 influence on your browsing unless you select them explicitly in the
1734 editor</emphasis>. A default installation should be pre-set to
1735 <literal>Cautious</literal>. New users should try this for a while before
1736 adjusting the settings to more aggressive levels. The more aggressive
1737 the settings, then the more likelihood there is of problems such as sites
1738 not working as they should.
1741 The <guibutton>Edit</guibutton> button allows you to turn each
1742 action on/off individually for fine-tuning. The <guibutton>Cautious</guibutton>
1743 button changes the actions list to low/safe settings which will activate
1744 ad blocking and a minimal set of &my-app;'s features, and subsequently
1745 there will be less of a chance for accidental problems. The
1746 <guibutton>Medium</guibutton> button sets the list to a medium level of
1747 other features and a low level set of privacy features. The
1748 <guibutton>Advanced</guibutton> button sets the list to a high level of
1749 ad blocking and medium level of privacy. See the chart below. The latter
1750 three buttons over-ride any changes via with the
1751 <guibutton>Edit</guibutton> button. More fine-tuning can be done in the
1752 lower sections of this internal page.
1755 While the actions file editor allows to enable these settings in all
1756 actions files, they are only supposed to be enabled in the first one
1757 to make sure you don't unintentionally overrule earlier rules.
1760 The default profiles, and their associated actions, as pre-defined in
1761 <filename>default.action</filename> are:
1763 <table frame=all id="default-configurations"><title>Default Configurations</title>
1764 <tgroup cols=4 align=left colsep=1 rowsep=1>
1765 <colspec colname=c1>
1766 <colspec colname=c2>
1767 <colspec colname=c3>
1768 <colspec colname=c4>
1771 <entry>Feature</entry>
1772 <entry>Cautious</entry>
1773 <entry>Medium</entry>
1774 <entry>Advanced</entry>
1779 <!-- <entry>f1</entry> -->
1780 <!-- <entry>f2</entry> -->
1781 <!-- <entry>f3</entry> -->
1782 <!-- <entry>f4</entry> -->
1788 <entry>Ad-blocking Aggressiveness</entry>
1789 <entry>medium</entry>
1795 <entry>Ad-filtering by size</entry>
1802 <entry>Ad-filtering by link</entry>
1808 <entry>Pop-up killing</entry>
1809 <entry>blocks only</entry>
1810 <entry>blocks only</entry>
1811 <entry>blocks only</entry>
1815 <entry>Privacy Features</entry>
1817 <entry>medium</entry>
1818 <entry>medium/high</entry>
1822 <entry>Cookie handling</entry>
1824 <entry>session-only</entry>
1829 <entry>Referer forging</entry>
1836 <entry>GIF de-animation</entry>
1843 <entry>Fast redirects</entry>
1850 <entry>HTML taming</entry>
1857 <entry>JavaScript taming</entry>
1864 <entry>Web-bug killing</entry>
1871 <entry>Image tag reordering</entry>
1885 The list of actions files to be used are defined in the main configuration
1886 file, and are processed in the order they are defined (e.g.
1887 <filename>default.action</filename> is typically processed before
1888 <filename>user.action</filename>). The content of these can all be viewed and
1890 url="http://config.privoxy.org/show-status">http://config.privoxy.org/show-status</ulink>.
1891 The over-riding principle when applying actions, is that the last action that
1892 matches a given URL wins. The broadest, most general rules go first
1893 (defined in <filename>default.action</filename>),
1894 followed by any exceptions (typically also in
1895 <filename>default.action</filename>), which are then followed lastly by any
1896 local preferences (typically in <emphasis>user</emphasis><filename>.action</filename>).
1897 Generally, <filename>user.action</filename> has the last word.
1901 An actions file typically has multiple sections. If you want to use
1902 <quote>aliases</quote> in an actions file, you have to place the (optional)
1903 <link linkend="aliases">alias section</link> at the top of that file.
1904 Then comes the default set of rules which will apply universally to all
1905 sites and pages (be <emphasis>very careful</emphasis> with using such a
1906 universal set in <filename>user.action</filename> or any other actions file after
1907 <filename>default.action</filename>, because it will override the result
1908 from consulting any previous file). And then below that,
1909 exceptions to the defined universal policies. You can regard
1910 <filename>user.action</filename> as an appendix to <filename>default.action</filename>,
1911 with the advantage that it is a separate file, which makes preserving your
1912 personal settings across <application>Privoxy</application> upgrades easier.
1916 Actions can be used to block anything you want, including ads, banners, or
1917 just some obnoxious URL whose content you would rather not see. Cookies can be accepted
1918 or rejected, or accepted only during the current browser session (i.e. not
1919 written to disk), content can be modified, some JavaScripts tamed, user-tracking
1920 fooled, and much more. See below for a <link linkend="actions">complete list
1924 <!-- ~~~~~ New section ~~~~~ -->
1925 <sect2 id="right-mix">
1926 <title>Finding the Right Mix</title>
1928 Note that some <link linkend="actions">actions</link>, like cookie suppression
1929 or script disabling, may render some sites unusable that rely on these
1930 techniques to work properly. Finding the right mix of actions is not always easy and
1931 certainly a matter of personal taste. And, things can always change, requiring
1932 refinements in the configuration. In general, it can be said that the more
1933 <quote>aggressive</quote> your default settings (in the top section of the
1934 actions file) are, the more exceptions for <quote>trusted</quote> sites you
1935 will have to make later. If, for example, you want to crunch all cookies per
1936 default, you'll have to make exceptions from that rule for sites that you
1937 regularly use and that require cookies for actually useful purposes, like maybe
1938 your bank, favorite shop, or newspaper.
1942 We have tried to provide you with reasonable rules to start from in the
1943 distribution actions files. But there is no general rule of thumb on these
1944 things. There just are too many variables, and sites are constantly changing.
1945 Sooner or later you will want to change the rules (and read this chapter again :).
1949 <!-- ~~~~~ New section ~~~~~ -->
1950 <sect2 id="how-to-edit">
1951 <title>How to Edit</title>
1953 The easiest way to edit the actions files is with a browser by
1954 using our browser-based editor, which can be reached from <ulink
1955 url="http://config.privoxy.org/show-status">http://config.privoxy.org/show-status</ulink>.
1956 Note: the config file option <link
1957 linkend="enable-edit-actions">enable-edit-actions</link> must be enabled for
1958 this to work. The editor allows both fine-grained control over every single
1959 feature on a per-URL basis, and easy choosing from wholesale sets of defaults
1960 like <quote>Cautious</quote>, <quote>Medium</quote> or
1961 <quote>Advanced</quote>. Warning: the <quote>Advanced</quote> setting is more
1962 aggressive, and will be more likely to cause problems for some sites.
1963 Experienced users only!
1967 If you prefer plain text editing to GUIs, you can of course also directly edit the
1968 the actions files with your favorite text editor. Look at
1969 <filename>default.action</filename> which is richly commented with many
1975 <sect2 id="actions-apply">
1976 <title>How Actions are Applied to Requests</title>
1978 Actions files are divided into sections. There are special sections,
1979 like the <quote><link linkend="aliases">alias</link></quote> sections which will
1980 be discussed later. For now let's concentrate on regular sections: They have a
1981 heading line (often split up to multiple lines for readability) which consist
1982 of a list of actions, separated by whitespace and enclosed in curly braces.
1983 Below that, there is a list of URL and tag patterns, each on a separate line.
1987 To determine which actions apply to a request, the URL of the request is
1988 compared to all URL patterns in each <quote>action file</quote>.
1989 Every time it matches, the list of applicable actions for the request is
1990 incrementally updated, using the heading of the section in which the
1991 pattern is located. The same is done again for tags and tag patterns later on.
1995 If multiple applying sections set the same action differently,
1996 the last match wins. If not, the effects are aggregated.
1997 E.g. a URL might match a regular section with a heading line of <literal>{
1998 +<link linkend="handle-as-image">handle-as-image</link> }</literal>,
1999 then later another one with just <literal>{
2000 +<link linkend="block">block</link> }</literal>, resulting
2001 in <emphasis>both</emphasis> actions to apply. And there may well be
2002 cases where you will want to combine actions together. Such a section then
2007 { +<literal>handle-as-image</literal> +<literal>block{Banner ads.}</literal> }
2008 # Block these as if they were images. Send no block page.
2010 media.example.com/.*banners
2011 .example.com/images/ads/</screen>
2014 You can trace this process for URL patterns and any given URL by visiting <ulink
2015 url="http://config.privoxy.org/show-url-info">http://config.privoxy.org/show-url-info</ulink>.
2019 Examples and more detail on this is provided in the Appendix, <link linkend="ACTIONSANAT">
2020 Troubleshooting: Anatomy of an Action</link> section.
2024 <!-- ~~~~~ New section ~~~~~ -->
2025 <sect2 id="af-patterns">
2026 <title>Patterns</title>
2028 As mentioned, <application>Privoxy</application> uses <quote>patterns</quote>
2029 to determine what <emphasis>actions</emphasis> might apply to which sites and
2030 pages your browser attempts to access. These <quote>patterns</quote> use wild
2031 card type <emphasis>pattern</emphasis> matching to achieve a high degree of
2032 flexibility. This allows one expression to be expanded and potentially match
2033 against many similar patterns.
2037 Generally, an URL pattern has the form
2038 <literal><host><port>/<path></literal>, where the
2039 <literal><host></literal>, the <literal><port></literal>
2040 and the <literal><path></literal> are optional. (This is why the special
2041 <literal>/</literal> pattern matches all URLs). Note that the protocol
2042 portion of the URL pattern (e.g. <literal>http://</literal>) should
2043 <emphasis>not</emphasis> be included in the pattern. This is assumed already!
2046 The pattern matching syntax is different for the host and path parts of
2047 the URL. The host part uses a simple globbing type matching technique,
2048 while the path part uses more flexible
2049 <ulink url="https://en.wikipedia.org/wiki/Regular_expressions"><quote>Regular
2050 Expressions</quote></ulink> (POSIX 1003.2).
2053 The port part of a pattern is a decimal port number preceded by a colon
2054 (<literal>:</literal>). If the host part contains a numerical IPv6 address,
2055 it has to be put into angle brackets
2056 (<literal><</literal>, <literal>></literal>).
2061 <term><literal>www.example.com/</literal></term>
2064 is a host-only pattern and will match any request to <literal>www.example.com</literal>,
2065 regardless of which document on that server is requested. So ALL pages in
2066 this domain would be covered by the scope of this action. Note that a
2067 simple <literal>example.com</literal> is different and would NOT match.
2072 <term><literal>www.example.com</literal></term>
2075 means exactly the same. For host-only patterns, the trailing <literal>/</literal> may
2081 <term><literal>www.example.com/index.html</literal></term>
2084 matches all the documents on <literal>www.example.com</literal>
2085 whose name starts with <literal>/index.html</literal>.
2090 <term><literal>www.example.com/index.html$</literal></term>
2093 matches only the single document <literal>/index.html</literal>
2094 on <literal>www.example.com</literal>.
2099 <term><literal>/index.html$</literal></term>
2102 matches the document <literal>/index.html</literal>, regardless of the domain,
2103 i.e. on <emphasis>any</emphasis> web server anywhere.
2108 <term><literal>/</literal></term>
2111 Matches any URL because there's no requirement for either the
2112 domain or the path to match anything.
2117 <term><literal>:8000/</literal></term>
2120 Matches any URL pointing to TCP port 8000.
2125 <term><literal>10.0.0.1/</literal></term>
2128 Matches any URL with the host address <literal>10.0.0.1</literal>.
2129 (Note that the real URL uses plain brackets, not angle brackets.)
2134 <term><literal><2001:db8::1>/</literal></term>
2137 Matches any URL with the host address <literal>2001:db8::1</literal>.
2138 (Note that the real URL uses plain brackets, not angle brackets.)
2143 <term><literal>index.html</literal></term>
2146 matches nothing, since it would be interpreted as a domain name and
2147 there is no top-level domain called <literal>.html</literal>. So its
2155 <!-- ~~~~~ New section ~~~~~ -->
2156 <sect3 id="host-pattern"><title>The Host Pattern</title>
2159 The matching of the host part offers some flexible options: if the
2160 host pattern starts or ends with a dot, it becomes unanchored at that end.
2161 The host pattern is often referred to as domain pattern as it is usually
2162 used to match domain names and not IP addresses.
2168 <term><literal>.example.com</literal></term>
2171 matches any domain with first-level domain <literal>com</literal>
2172 and second-level domain <literal>example</literal>.
2173 For example <literal>www.example.com</literal>,
2174 <literal>example.com</literal> and <literal>foo.bar.baz.example.com</literal>.
2175 Note that it wouldn't match if the second-level domain was <literal>another-example</literal>.
2180 <term><literal>www.</literal></term>
2183 matches any domain that <emphasis>STARTS</emphasis> with
2184 <literal>www.</literal> (It also matches the domain
2185 <literal>www</literal> but most of the time that doesn't matter.)
2190 <term><literal>.example.</literal></term>
2193 matches any domain that <emphasis>CONTAINS</emphasis> <literal>.example.</literal>.
2194 And, by the way, also included would be any files or documents that exist
2195 within that domain since no path limitations are specified. (Correctly
2196 speaking: It matches any FQDN that contains <literal>example</literal> as
2197 a domain.) This might be <literal>www.example.com</literal>,
2198 <literal>news.example.de</literal>, or
2199 <literal>www.example.net/cgi/testing.pl</literal> for instance. All these
2207 Additionally, there are wild-cards that you can use in the domain names
2208 themselves. These work similarly to shell globbing type wild-cards:
2209 <quote>*</quote> represents zero or more arbitrary characters (this is
2211 <ulink url="https://en.wikipedia.org/wiki/Regular_expressions"><quote>Regular
2212 Expression</quote></ulink> based syntax of <quote>.*</quote>),
2213 <quote>?</quote> represents any single character (this is equivalent to the
2214 regular expression syntax of a simple <quote>.</quote>), and you can define
2215 <quote>character classes</quote> in square brackets which is similar to
2216 the same regular expression technique. All of this can be freely mixed:
2221 <term><literal>ad*.example.com</literal></term>
2224 matches <quote>adserver.example.com</quote>,
2225 <quote>ads.example.com</quote>, etc but not <quote>sfads.example.com</quote>
2230 <term><literal>*ad*.example.com</literal></term>
2233 matches all of the above, and then some.
2238 <term><literal>.?pix.com</literal></term>
2241 matches <literal>www.ipix.com</literal>,
2242 <literal>pictures.epix.com</literal>, <literal>a.b.c.d.e.upix.com</literal> etc.
2247 <term><literal>www[1-9a-ez].example.c*</literal></term>
2250 matches <literal>www1.example.com</literal>,
2251 <literal>www4.example.cc</literal>, <literal>wwwd.example.cy</literal>,
2252 <literal>wwwz.example.com</literal> etc., but <emphasis>not</emphasis>
2253 <literal>wwww.example.com</literal>.
2260 While flexible, this is not the sophistication of full regular expression based syntax.
2264 When compiled with FEATURE_PCRE_HOST_PATTERNS patterns can be prefixed with
2265 <quote>PCRE-HOST-PATTERN:</quote> in which case full regular expression
2266 (PCRE) can be used for the host pattern as well.
2271 <!-- ~ End section ~ -->
2274 <!-- ~~~~~ New section ~~~~~ -->
2275 <sect3 id="path-pattern"><title>The Path Pattern</title>
2278 <application>Privoxy</application> uses <quote>modern</quote> POSIX 1003.2
2279 <ulink url="https://en.wikipedia.org/wiki/Regular_expressions"><quote>Regular
2280 Expressions</quote></ulink> for matching the path portion (after the slash),
2281 and is thus more flexible.
2285 There is an <link linkend="regex">Appendix</link> with a brief quick-start into regular
2286 expressions, you also might want to have a look at your operating system's documentation
2287 on regular expressions (try <literal>man re_format</literal>).
2291 Note that the path pattern is automatically left-anchored at the <quote>/</quote>,
2292 i.e. it matches as if it would start with a <quote>^</quote> (regular expression speak
2293 for the beginning of a line).
2297 Please also note that matching in the path is <emphasis>CASE INSENSITIVE</emphasis>
2298 by default, but you can switch to case sensitive at any point in the pattern by using the
2299 <quote>(?-i)</quote> switch: <literal>www.example.com/(?-i)PaTtErN.*</literal> will match
2300 only documents whose path starts with <literal>PaTtErN</literal> in
2301 <emphasis>exactly</emphasis> this capitalization.
2306 <term><literal>.example.com/.*</literal></term>
2309 Is equivalent to just <quote>.example.com</quote>, since any documents
2310 within that domain are matched with or without the <quote>.*</quote>
2311 regular expression. This is redundant
2316 <term><literal>.example.com/.*/index.html$</literal></term>
2319 Will match any page in the domain of <quote>example.com</quote> that is
2320 named <quote>index.html</quote>, and that is part of some path. For
2321 example, it matches <quote>www.example.com/testing/index.html</quote> but
2322 NOT <quote>www.example.com/index.html</quote> because the regular
2323 expression called for at least two <quote>/'s</quote>, thus the path
2324 requirement. It also would match
2325 <quote>www.example.com/testing/index_html</quote>, because of the
2326 special meta-character <quote>.</quote>.
2331 <term><literal>.example.com/(.*/)?index\.html$</literal></term>
2334 This regular expression is conditional so it will match any page
2335 named <quote>index.html</quote> regardless of path which in this case can
2336 have one or more <quote>/'s</quote>. And this one must contain exactly
2337 <quote>.html</quote> (and end with that!).
2342 <term><literal>.example.com/(.*/)(ads|banners?|junk)</literal></term>
2345 This regular expression will match any path of <quote>example.com</quote>
2346 that contains any of the words <quote>ads</quote>, <quote>banner</quote>,
2347 <quote>banners</quote> (because of the <quote>?</quote>) or <quote>junk</quote>.
2348 The path does not have to end in these words, just contain them.
2349 The path has to contain at least two slashes (including the one at the beginning).
2354 <term><literal>.example.com/(.*/)(ads|banners?|junk)/.*\.(jpe?g|gif|png)$</literal></term>
2357 This is very much the same as above, except now it must end in either
2358 <quote>.jpg</quote>, <quote>.jpeg</quote>, <quote>.gif</quote> or <quote>.png</quote>. So this
2359 one is limited to common image formats.
2366 There are many, many good examples to be found in <filename>default.action</filename>,
2367 and more tutorials below in <link linkend="regex">Appendix on regular expressions</link>.
2372 <!-- ~ End section ~ -->
2375 <!-- ~~~~~ New section ~~~~~ -->
2376 <sect3 id="tag-pattern"><title>The Request Tag Pattern</title>
2379 Request tag patterns are used to change the applying actions based on the
2380 request's tags. Tags can be created based on HTTP headers with either
2381 the <link linkend="CLIENT-HEADER-TAGGER">client-header-tagger</link>
2382 or the <link linkend="SERVER-HEADER-TAGGER">server-header-tagger</link> action.
2386 Request tag patterns have to start with <quote>TAG:</quote>, so &my-app;
2387 can tell them apart from other patterns. Everything after the colon
2388 including white space, is interpreted as a regular expression with
2389 path pattern syntax, except that tag patterns aren't left-anchored
2390 automatically (&my-app; doesn't silently add a <quote>^</quote>,
2391 you have to do it yourself if you need it).
2395 To match all requests that are tagged with <quote>foo</quote>
2396 your pattern line should be <quote>TAG:^foo$</quote>,
2397 <quote>TAG:foo</quote> would work as well, but it would also
2398 match requests whose tags contain <quote>foo</quote> somewhere.
2399 <quote>TAG: foo</quote> wouldn't work as it requires white space.
2403 Sections can contain URL and request tag patterns at the same time,
2404 but request tag patterns are checked after the URL patterns and thus
2405 always overrule them, even if they are located before the URL patterns.
2409 Once a new request tag is added, Privoxy checks right away if it's matched by one
2410 of the request tag patterns and updates the action settings accordingly. As a result
2411 request tags can be used to activate other tagger actions, as long as these other
2412 taggers look for headers that haven't already be parsed.
2416 For example you could tag client requests which use the
2417 <literal>POST</literal> method,
2418 then use this tag to activate another tagger that adds a tag if cookies
2419 are sent, and then use a block action based on the cookie tag. This allows
2420 the outcome of one action, to be input into a subsequent action. However if
2421 you'd reverse the position of the described taggers, and activated the
2422 method tagger based on the cookie tagger, no method tags would be created.
2423 The method tagger would look for the request line, but at the time
2424 the cookie tag is created, the request line has already been parsed.
2428 While this is a limitation you should be aware of, this kind of
2429 indirection is seldom needed anyway and even the example doesn't
2430 make too much sense.
2435 <!-- ~~~~~ New section ~~~~~ -->
2436 <sect3 id="negative-tag-patterns"><title>The Negative Request Tag Patterns</title>
2439 To match requests that do not have a certain request tag, specify a negative tag pattern
2440 by prefixing the tag pattern line with either <quote>NO-REQUEST-TAG:</quote>
2441 or <quote>NO-RESPONSE-TAG:</quote> instead of <quote>TAG:</quote>.
2445 Negative request tag patterns created with <quote>NO-REQUEST-TAG:</quote> are checked
2446 after all client headers are scanned, the ones created with <quote>NO-RESPONSE-TAG:</quote>
2447 are checked after all server headers are scanned. In both cases all the created
2448 tags are considered.
2452 <!-- ~~~~~ New section ~~~~~ -->
2453 <sect3 id="client-tag-pattern"><title>The Client Tag Pattern</title>
2455 <!-- XXX: This section contains duplicates content from the
2456 client-specific-tag documentation. -->
2460 This is an experimental feature. The syntax is likely to change in future versions.
2465 Client tag patterns are not set based on HTTP headers but based on
2466 the client's IP address. Users can enable them themselves, but the
2467 Privoxy admin controls which tags are available and what their effect
2472 After a client-specific tag has been defined with the
2473 <link linkend="client-specific-tag">client-specific-tag</link>,
2474 directive, action sections can be activated based on the tag by using a
2475 CLIENT-TAG pattern. The CLIENT-TAG pattern is evaluated at the same priority
2476 as URL patterns, as a result the last matching pattern wins. Tags that
2477 are created based on client or server headers are evaluated later on
2478 and can overrule CLIENT-TAG and URL patterns!
2481 The tag is set for all requests that come from clients that requested
2482 it to be set. Note that "clients" are differentiated by IP address,
2483 if the IP address changes the tag has to be requested again.
2486 Clients can request tags to be set by using the CGI interface <ulink
2487 url="http://config.privoxy.org/client-tags">http://config.privoxy.org/client-tags</ulink>.
2495 # If the admin defined the client-specific-tag circumvent-blocks,
2496 # and the request comes from a client that previously requested
2497 # the tag to be set, overrule all previous +block actions that
2498 # are enabled based on URL to CLIENT-TAG patterns.
2500 CLIENT-TAG:^circumvent-blocks$
2502 # This section is not overruled because it's located after
2504 {+block{Nobody is supposed to request this.}}
2505 example.org/blocked-example-page</screen>
2511 <!-- ~ End section ~ -->
2514 <!-- ~~~~~ New section ~~~~~ -->
2516 <sect2 id="actions">
2517 <title>Actions</title>
2519 All actions are disabled by default, until they are explicitly enabled
2520 somewhere in an actions file. Actions are turned on if preceded with a
2521 <quote>+</quote>, and turned off if preceded with a <quote>-</quote>. So a
2522 <literal>+action</literal> means <quote>do that action</quote>, e.g.
2523 <literal>+block</literal> means <quote>please block URLs that match the
2524 following patterns</quote>, and <literal>-block</literal> means <quote>don't
2525 block URLs that match the following patterns, even if <literal>+block</literal>
2526 previously applied.</quote>
2530 Again, actions are invoked by placing them on a line, enclosed in curly braces and
2531 separated by whitespace, like in
2532 <literal>{+some-action -some-other-action{some-parameter}}</literal>,
2533 followed by a list of URL patterns, one per line, to which they apply.
2534 Together, the actions line and the following pattern lines make up a section
2535 of the actions file.
2539 Actions fall into three categories:
2545 Boolean, i.e the action can only be <quote>enabled</quote> or
2546 <quote>disabled</quote>. Syntax:
2549 +<replaceable class="function">name</replaceable> # enable action <replaceable class="parameter">name</replaceable>
2550 -<replaceable class="function">name</replaceable> # disable action <replaceable class="parameter">name</replaceable></screen>
2552 Example: <literal>+handle-as-image</literal>
2559 Parameterized, where some value is required in order to enable this type of action.
2563 +<replaceable class="function">name</replaceable>{<replaceable class="parameter">param</replaceable>} # enable action and set parameter to <replaceable class="parameter">param</replaceable>,
2564 # overwriting parameter from previous match if necessary
2565 -<replaceable class="function">name</replaceable> # disable action. The parameter can be omitted</screen>
2567 Note that if the URL matches multiple positive forms of a parameterized action,
2568 the last match wins, i.e. the params from earlier matches are simply ignored.
2571 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>
2577 Multi-value. These look exactly like parameterized actions,
2578 but they behave differently: If the action applies multiple times to the
2579 same URL, but with different parameters, <emphasis>all</emphasis> the parameters
2580 from <emphasis>all</emphasis> matches are remembered. This is used for actions
2581 that can be executed for the same request repeatedly, like adding multiple
2582 headers, or filtering through multiple filters. Syntax:
2585 +<replaceable class="function">name</replaceable>{<replaceable class="parameter">param</replaceable>} # enable action and add <replaceable class="parameter">param</replaceable> to the list of parameters
2586 -<replaceable class="function">name</replaceable>{<replaceable class="parameter">param</replaceable>} # remove the parameter <replaceable class="parameter">param</replaceable> from the list of parameters
2587 # If it was the last one left, disable the action.
2588 <replaceable class="parameter">-name</replaceable> # disable this action completely and remove all parameters from the list</screen>
2590 Examples: <literal>+add-header{X-Fun-Header: Some text}</literal> and
2591 <literal>+filter{html-annoyances}</literal>
2598 If nothing is specified in any actions file, no <quote>actions</quote> are
2599 taken. So in this case <application>Privoxy</application> would just be a
2600 normal, non-blocking, non-filtering proxy. You must specifically enable the
2601 privacy and blocking features you need (although the provided default actions
2602 files will give a good starting point).
2606 Later defined action sections always over-ride earlier ones of the same type.
2607 So exceptions to any rules you make, should come in the latter part of the file (or
2608 in a file that is processed later when using multiple actions files such
2609 as <filename>user.action</filename>). For multi-valued actions, the actions
2610 are applied in the order they are specified. Actions files are processed in
2611 the order they are defined in <filename>config</filename> (the default
2612 installation has three actions files). It also quite possible for any given
2613 URL to match more than one <quote>pattern</quote> (because of wildcards and
2614 regular expressions), and thus to trigger more than one set of actions! Last
2618 <!-- start actions listing -->
2620 The list of valid <application>Privoxy</application> actions are:
2624 <!-- ********************************************************** -->
2625 <!-- Please note the below defined actions use id's that are -->
2626 <!-- probably linked from other places, so please don't change. -->
2628 <!-- ********************************************************** -->
2631 <!-- ~~~~~ New section ~~~~~ -->
2633 <sect3 renderas="sect4" id="add-header">
2634 <title>add-header</title>
2638 <term>Typical use:</term>
2640 <para>Confuse log analysis, custom applications</para>
2645 <term>Effect:</term>
2648 Sends a user defined HTTP header to the web server.
2655 <!-- boolean, parameterized, Multi-value -->
2657 <para>Multi-value.</para>
2662 <term>Parameter:</term>
2665 Any string value is possible. Validity of the defined HTTP headers is not checked.
2666 It is recommended that you use the <quote><literal>X-</literal></quote> prefix
2676 This action may be specified multiple times, in order to define multiple
2677 headers. This is rarely needed for the typical user. If you don't know what
2678 <quote>HTTP headers</quote> are, you definitely don't need to worry about this
2682 Headers added by this action are not modified by other actions.
2688 <term>Example usage:</term>
2690 <screen># Add a DNT ("Do not track") header to all requests,
2691 # event to those that already have one.
2693 # This is just an example, not a recommendation.
2695 # There is no reason to believe that user-tracking websites care
2696 # about the DNT header and depending on the User-Agent, adding the
2697 # header may make user-tracking easier.
2698 {+add-header{DNT: 1}}
2706 <!-- ~~~~~ New section ~~~~~ -->
2707 <sect3 renderas="sect4" id="block">
2708 <title>block</title>
2712 <term>Typical use:</term>
2714 <para>Block ads or other unwanted content</para>
2719 <term>Effect:</term>
2722 Requests for URLs to which this action applies are blocked, i.e. the
2723 requests are trapped by &my-app; and the requested URL is never retrieved,
2724 but is answered locally with a substitute page or image, as determined by
2726 linkend="handle-as-image">handle-as-image</link></literal>,
2728 linkend="set-image-blocker">set-image-blocker</link></literal>, and
2730 linkend="handle-as-empty-document">handle-as-empty-document</link></literal> actions.
2738 <!-- boolean, parameterized, Multi-value -->
2740 <para>Parameterized.</para>
2745 <term>Parameter:</term>
2747 <para>A block reason that should be given to the user.</para>
2755 <application>Privoxy</application> sends a special <quote>BLOCKED</quote> page
2756 for requests to blocked pages. This page contains the block reason given as
2757 parameter, a link to find out why the block action applies, and a click-through
2758 to the blocked content (the latter only if the force feature is available and
2762 A very important exception occurs if <emphasis>both</emphasis>
2763 <literal>block</literal> and <literal><link linkend="handle-as-image">handle-as-image</link></literal>,
2764 apply to the same request: it will then be replaced by an image. If
2765 <literal><link linkend="set-image-blocker">set-image-blocker</link></literal>
2766 (see below) also applies, the type of image will be determined by its parameter,
2767 if not, the standard checkerboard pattern is sent.
2770 It is important to understand this process, in order
2771 to understand how <application>Privoxy</application> deals with
2772 ads and other unwanted content. Blocking is a core feature, and one
2773 upon which various other features depend.
2776 The <literal><link linkend="filter">filter</link></literal>
2777 action can perform a very similar task, by <quote>blocking</quote>
2778 banner images and other content through rewriting the relevant URLs in the
2779 document's HTML source, so they don't get requested in the first place.
2780 Note that this is a totally different technique, and it's easy to confuse the two.
2786 <term>Example usage (section):</term>
2788 <screen>{+block{No nasty stuff for you.}}
2789 # Block and replace with "blocked" page
2790 .nasty-stuff.example.com
2792 {+block{Doubleclick banners.} +handle-as-image}
2793 # Block and replace with image
2797 {+block{Layered ads.} +handle-as-empty-document}
2798 # Block and then ignore
2799 adserver.example.net/.*\.js$</screen>
2808 <!-- ~~~~~ New section ~~~~~ -->
2809 <sect3 renderas="sect4" id="change-x-forwarded-for">
2810 <title>change-x-forwarded-for</title>
2814 <term>Typical use:</term>
2816 <para>Improve privacy by not forwarding the source of the request in the HTTP headers.</para>
2821 <term>Effect:</term>
2824 Deletes the <quote>X-Forwarded-For:</quote> HTTP header from the client request,
2832 <!-- Boolean, Parameterized, Multi-value -->
2834 <para>Parameterized.</para>
2839 <term>Parameter:</term>
2843 <para><quote>block</quote> to delete the header.</para>
2847 <quote>add</quote> to create the header (or append
2848 the client's IP address to an already existing one).
2859 It is safe and recommended to use <literal>block</literal>.
2862 Forwarding the source address of the request may make
2863 sense in some multi-user setups but is also a privacy risk.
2868 <term>Example usage:</term>
2870 <screen>+change-x-forwarded-for{block}</screen>
2876 <!-- ~~~~~ New section ~~~~~ -->
2877 <sect3 renderas="sect4" id="client-header-filter">
2878 <title>client-header-filter</title>
2882 <term>Typical use:</term>
2885 Rewrite or remove single client headers.
2891 <term>Effect:</term>
2894 All client headers to which this action applies are filtered on-the-fly through
2895 the specified regular expression based substitutions.
2902 <!-- boolean, parameterized, Multi-value -->
2904 <para>Multi-value.</para>
2909 <term>Parameter:</term>
2912 The name of a client-header filter, as defined in one of the
2913 <link linkend="filter-file">filter files</link>.
2922 Client-header filters are applied to each header on its own, not to
2923 all at once. This makes it easier to diagnose problems, but on the downside
2924 you can't write filters that only change header x if header y's value is z.
2925 You can do that by using tags though.
2928 Client-header filters are executed after the other header actions have finished
2929 and use their output as input.
2932 If the request URI gets changed, &my-app; will detect that and use the new
2933 one. This can be used to rewrite the request destination behind the client's
2934 back, for example to specify a Tor exit relay for certain requests.
2937 Note that to change the destination host for
2938 <link linkend="HTTPS-INSPECTION">https-inspected</link>
2939 requests a protocol and host has to be added to the URI.
2942 If <link linkend="HTTPS-INSPECTION">https inspection</link>
2943 is enabled, the protocol can be downgraded from https to http
2944 but upgrading a request from http to https is currently not
2948 After detecting a rewrite, &my-app; does not update the actions
2949 used for the request based on the new host.
2952 Please refer to the <link linkend="filter-file">filter file chapter</link>
2953 to learn which client-header filters are available by default, and how to
2961 <term>Example usage (section):</term>
2964 # Hide Tor exit notation in Host and Referer Headers
2965 {+client-header-filter{hide-tor-exit-notation}}
2974 <!-- ~~~~~ New section ~~~~~ -->
2975 <sect3 renderas="sect4" id="client-body-filter">
2976 <title>client-body-filter</title>
2980 <term>Typical use:</term>
2983 Rewrite or remove client request body.
2989 <term>Effect:</term>
2992 All request bodies to which this action applies are filtered on-the-fly through
2993 the specified regular expression based substitutions.
3000 <!-- boolean, parameterized, Multi-value -->
3002 <para>Multi-value.</para>
3007 <term>Parameter:</term>
3010 The name of a client-body filter, as defined in one of the
3011 <link linkend="filter-file">filter files</link>.
3020 Please refer to the <link linkend="filter-file">filter file chapter</link>
3021 to learn how to create your own client-body filters.
3024 The distribution <filename>default.filter</filename> file contains a selection of
3025 client-body filters for example purposes.
3028 The amount of data that can be filtered is limited by the
3029 <literal><link linkend="buffer-limit">buffer-limit</link></literal>
3030 option in the main <link linkend="config">config file</link>. The
3031 default is 4096 KB (4 Megs). Once this limit is exceeded, the whole
3032 request body is passed through unfiltered.
3038 <term>Example usage (section):</term>
3041 # Remove "test" everywhere in the request body
3042 {+client-body-filter{remove-test}}
3052 <!-- ~~~~~ New section ~~~~~ -->
3053 <sect3 renderas="sect4" id="client-header-tagger">
3054 <title>client-header-tagger</title>
3058 <term>Typical use:</term>
3061 Block requests based on their headers.
3067 <term>Effect:</term>
3070 Client headers to which this action applies are filtered on-the-fly through
3071 the specified regular expression based substitutions, the result is used as
3079 <!-- boolean, parameterized, Multi-value -->
3081 <para>Multi-value.</para>
3086 <term>Parameter:</term>
3089 The name of a client-header tagger, as defined in one of the
3090 <link linkend="filter-file">filter files</link>.
3099 Client-header taggers are applied to each header on its own,
3100 and as the header isn't modified, each tagger <quote>sees</quote>
3104 Client-header taggers are the first actions that are executed
3105 and their tags can be used to control every other action.
3111 <term>Example usage (section):</term>
3114 # Tag every request with the User-Agent header
3115 {+client-header-tagger{user-agent}}
3118 # Tagging itself doesn't change the action
3119 # settings, sections with TAG patterns do:
3121 # If it's a download agent, use a different forwarding proxy,
3122 # show the real User-Agent and make sure resume works.
3123 {+forward-override{forward-socks5 10.0.0.2:2222 .} \
3124 -hide-if-modified-since \
3125 -overwrite-last-modified \
3130 TAG:^User-Agent: NetBSD-ftp/
3131 TAG:^User-Agent: Novell ZYPP Installer
3132 TAG:^User-Agent: RPM APT-HTTP/
3133 TAG:^User-Agent: fetch libfetch/
3134 TAG:^User-Agent: Ubuntu APT-HTTP/
3135 TAG:^User-Agent: MPlayer/
3139 # Tag all requests with the Range header set
3140 {+client-header-tagger{range-requests}}
3143 # Disable filtering for the tagged requests.
3145 # With filtering enabled Privoxy would remove the Range headers
3146 # to be able to filter the whole response. The downside is that
3147 # it prevents clients from resuming downloads or skipping over
3148 # parts of multimedia files.
3149 {-filter -deanimate-gifs}
3154 # Tag all requests with the client IP address
3156 # (Technically the client IP address isn't included in the
3157 # client headers but client-header taggers can set it anyway.
3158 # For details see the tagger in default.filter)
3159 {+client-header-tagger{client-ip-address}}
3162 # Change forwarding settings for requests coming from address 10.0.0.1
3163 {+forward-override{forward-socks5 127.0.1.2:2222 .}}
3164 TAG:^IP-ADDRESS: 10\.0\.0\.1$
3173 <!-- ~~~~~ New section ~~~~~ -->
3174 <sect3 renderas="sect4" id="content-type-overwrite">
3175 <title>content-type-overwrite</title>
3179 <term>Typical use:</term>
3181 <para>Stop useless download menus from popping up, or change the browser's rendering mode</para>
3186 <term>Effect:</term>
3189 Replaces the <quote>Content-Type:</quote> HTTP server header.
3196 <!-- Boolean, Parameterized, Multi-value -->
3198 <para>Parameterized.</para>
3203 <term>Parameter:</term>
3215 The <quote>Content-Type:</quote> HTTP server header is used by the
3216 browser to decide what to do with the document. The value of this
3217 header can cause the browser to open a download menu instead of
3218 displaying the document by itself, even if the document's format is
3219 supported by the browser.
3222 The declared content type can also affect which rendering mode
3223 the browser chooses. If XHTML is delivered as <quote>text/html</quote>,
3224 many browsers treat it as yet another broken HTML document.
3225 If it is send as <quote>application/xml</quote>, browsers with
3226 XHTML support will only display it, if the syntax is correct.
3229 If you see a web site that proudly uses XHTML buttons, but sets
3230 <quote>Content-Type: text/html</quote>, you can use &my-app;
3231 to overwrite it with <quote>application/xml</quote> and validate
3232 the web master's claim inside your XHTML-supporting browser.
3233 If the syntax is incorrect, the browser will complain loudly.
3236 You can also go the opposite direction: if your browser prints
3237 error messages instead of rendering a document falsely declared
3238 as XHTML, you can overwrite the content type with
3239 <quote>text/html</quote> and have it rendered as broken HTML document.
3242 By default <literal>content-type-overwrite</literal> only replaces
3243 <quote>Content-Type:</quote> headers that look like some kind of text.
3244 If you want to overwrite it unconditionally, you have to combine it with
3245 <literal><link linkend="force-text-mode">force-text-mode</link></literal>.
3246 This limitation exists for a reason, think twice before circumventing it.
3249 Most of the time it's easier to replace this action with a custom
3250 <literal><link linkend="server-header-filter">server-header filter</link></literal>.
3251 It allows you to activate it for every document of a certain site and it will still
3252 only replace the content types you aimed at.
3255 Of course you can apply <literal>content-type-overwrite</literal>
3256 to a whole site and then make URL based exceptions, but it's a lot
3257 more work to get the same precision.
3263 <term>Example usage (sections):</term>
3265 <screen># Check if www.example.net/ really uses valid XHTML
3266 { +content-type-overwrite{application/xml} }
3269 # but leave the content type unmodified if the URL looks like a style sheet
3270 {-content-type-overwrite}
3271 www.example.net/.*\.css$
3272 www.example.net/.*style
3280 <!-- ~~~~~ New section ~~~~~ -->
3281 <sect3 renderas="sect4" id="crunch-client-header">
3285 <title>crunch-client-header</title>
3289 <term>Typical use:</term>
3291 <para>Remove a client header <application>Privoxy</application> has no dedicated action for.</para>
3296 <term>Effect:</term>
3299 Deletes every header sent by the client that contains the string the user supplied as parameter.
3306 <!-- Boolean, Parameterized, Multi-value -->
3308 <para>Parameterized.</para>
3313 <term>Parameter:</term>
3325 This action allows you to block client headers for which no dedicated
3326 <application>Privoxy</application> action exists.
3327 <application>Privoxy</application> will remove every client header that
3328 contains the string you supplied as parameter.
3331 Regular expressions are <emphasis>not supported</emphasis> and you can't
3332 use this action to block different headers in the same request, unless
3333 they contain the same string.
3336 <literal>crunch-client-header</literal> is only meant for quick tests.
3337 If you have to block several different headers, or only want to modify
3338 parts of them, you should use a
3339 <literal><link linkend="client-header-filter">client-header filter</link></literal>.
3343 Don't block any header without understanding the consequences.
3350 <term>Example usage (section):</term>
3352 <screen># Block the non-existent "Privacy-Violation:" client header
3353 { +crunch-client-header{Privacy-Violation:} }
3362 <!-- ~~~~~ New section ~~~~~ -->
3363 <sect3 renderas="sect4" id="crunch-if-none-match">
3364 <title>crunch-if-none-match</title>
3370 <term>Typical use:</term>
3372 <para>Prevent yet another way to track the user's steps between sessions.</para>
3377 <term>Effect:</term>
3380 Deletes the <quote>If-None-Match:</quote> HTTP client header.
3387 <!-- Boolean, Parameterized, Multi-value -->
3389 <para>Boolean.</para>
3394 <term>Parameter:</term>
3406 Removing the <quote>If-None-Match:</quote> HTTP client header
3407 is useful for filter testing, where you want to force a real
3408 reload instead of getting status code <quote>304</quote> which
3409 would cause the browser to use a cached copy of the page.
3412 It is also useful to make sure the header isn't used as a cookie
3413 replacement (unlikely but possible).
3416 Blocking the <quote>If-None-Match:</quote> header shouldn't cause any
3417 caching problems, as long as the <quote>If-Modified-Since:</quote> header
3418 isn't blocked or missing as well.
3421 It is recommended to use this action together with
3422 <literal><link linkend="hide-if-modified-since">hide-if-modified-since</link></literal>
3424 <literal><link linkend="overwrite-last-modified">overwrite-last-modified</link></literal>.
3430 <term>Example usage (section):</term>
3432 <screen># Let the browser revalidate cached documents but don't
3433 # allow the server to use the revalidation headers for user tracking.
3434 {+hide-if-modified-since{-60} \
3435 +overwrite-last-modified{randomize} \
3436 +crunch-if-none-match}
3445 <!-- ~~~~~ New section ~~~~~ -->
3446 <sect3 renderas="sect4" id="crunch-incoming-cookies">
3447 <title>crunch-incoming-cookies</title>
3451 <term>Typical use:</term>
3454 Prevent the web server from setting HTTP cookies on your system
3460 <term>Effect:</term>
3463 Deletes any <quote>Set-Cookie:</quote> HTTP headers from server replies.
3470 <!-- Boolean, Parameterized, Multi-value -->
3472 <para>Boolean.</para>
3477 <term>Parameter:</term>
3489 This action is only concerned with <emphasis>incoming</emphasis> HTTP cookies. For
3490 <emphasis>outgoing</emphasis> HTTP cookies, use
3491 <literal><link linkend="crunch-outgoing-cookies">crunch-outgoing-cookies</link></literal>.
3492 Use <emphasis>both</emphasis> to disable HTTP cookies completely.
3495 It makes <emphasis>no sense at all</emphasis> to use this action in conjunction
3496 with the <literal><link linkend="session-cookies-only">session-cookies-only</link></literal> action,
3497 since it would prevent the session cookies from being set. See also
3498 <literal><link linkend="filter-content-cookies">filter-content-cookies</link></literal>.
3504 <term>Example usage:</term>
3506 <screen>+crunch-incoming-cookies</screen>
3513 <!-- ~~~~~ New section ~~~~~ -->
3514 <sect3 renderas="sect4" id="crunch-server-header">
3515 <title>crunch-server-header</title>
3521 <term>Typical use:</term>
3523 <para>Remove a server header <application>Privoxy</application> has no dedicated action for.</para>
3528 <term>Effect:</term>
3531 Deletes every header sent by the server that contains the string the user supplied as parameter.
3538 <!-- Boolean, Parameterized, Multi-value -->
3540 <para>Parameterized.</para>
3545 <term>Parameter:</term>
3557 This action allows you to block server headers for which no dedicated
3558 <application>Privoxy</application> action exists. <application>Privoxy</application>
3559 will remove every server header that contains the string you supplied as parameter.
3562 Regular expressions are <emphasis>not supported</emphasis> and you can't
3563 use this action to block different headers in the same request, unless
3564 they contain the same string.
3567 <literal>crunch-server-header</literal> is only meant for quick tests.
3568 If you have to block several different headers, or only want to modify
3569 parts of them, you should use a custom
3570 <literal><link linkend="server-header-filter">server-header filter</link></literal>.
3574 Don't block any header without understanding the consequences.
3581 <term>Example usage (section):</term>
3583 <screen># Crunch server headers that try to prevent caching
3584 { +crunch-server-header{no-cache} }
3593 <!-- ~~~~~ New section ~~~~~ -->
3594 <sect3 renderas="sect4" id="crunch-outgoing-cookies">
3595 <title>crunch-outgoing-cookies</title>
3599 <term>Typical use:</term>
3602 Prevent the web server from reading any HTTP cookies from your system
3608 <term>Effect:</term>
3611 Deletes any <quote>Cookie:</quote> HTTP headers from client requests.
3618 <!-- Boolean, Parameterized, Multi-value -->
3620 <para>Boolean.</para>
3625 <term>Parameter:</term>
3637 This action is only concerned with <emphasis>outgoing</emphasis> HTTP cookies. For
3638 <emphasis>incoming</emphasis> HTTP cookies, use
3639 <literal><link linkend="crunch-incoming-cookies">crunch-incoming-cookies</link></literal>.
3640 Use <emphasis>both</emphasis> to disable HTTP cookies completely.
3643 It makes <emphasis>no sense at all</emphasis> to use this action in conjunction
3644 with the <literal><link linkend="session-cookies-only">session-cookies-only</link></literal> action,
3645 since it would prevent the session cookies from being read.
3651 <term>Example usage:</term>
3653 <screen>+crunch-outgoing-cookies</screen>
3661 <!-- ~~~~~ New section ~~~~~ -->
3662 <sect3 renderas="sect4" id="deanimate-gifs">
3663 <title>deanimate-gifs</title>
3667 <term>Typical use:</term>
3669 <para>Stop those annoying, distracting animated GIF images.</para>
3674 <term>Effect:</term>
3677 De-animate GIF animations, i.e. reduce them to their first or last image.
3684 <!-- boolean, parameterized, Multi-value -->
3686 <para>Parameterized.</para>
3691 <term>Parameter:</term>
3694 <quote>last</quote> or <quote>first</quote>
3703 This will also shrink the images considerably (in bytes, not pixels!). If
3704 the option <quote>first</quote> is given, the first frame of the animation
3705 is used as the replacement. If <quote>last</quote> is given, the last
3706 frame of the animation is used instead, which probably makes more sense for
3707 most banner animations, but also has the risk of not showing the entire
3708 last frame (if it is only a delta to an earlier frame).
3711 You can safely use this action with patterns that will also match non-GIF
3712 objects, because no attempt will be made at anything that doesn't look like
3719 <term>Example usage:</term>
3721 <screen>+deanimate-gifs{last}</screen>
3728 <!-- ~~~~~ New section ~~~~~ -->
3729 <sect3 renderas="sect4" id="delay-response">
3730 <title>delay-response</title>
3734 <term>Typical use:</term>
3736 <para>Delay responses to the client to reduce the load</para>
3741 <term>Effect:</term>
3744 Delays responses to the client by sending the response in ca. 10 byte chunks.
3751 <!-- boolean, parameterized, Multi-value -->
3753 <para>Parameterized.</para>
3758 <term>Parameter:</term>
3761 <quote>Number of milliseconds</quote>
3770 Sometimes when JavaScript code is used to fetch advertisements
3771 it doesn't respect Privoxy's blocks and retries to fetch the
3772 same resource again causing unnecessary load on the client.
3775 This action delays responses to the client and can be combined
3776 with <literal><link linkend="block">blocks</link></literal>
3777 to slow down the JavaScript code, thus reducing
3778 the load on the client.
3781 When used without <literal><link linkend="block">blocks</link></literal>
3782 the action can also be used to simulate a slow internet connection.
3788 <term>Example usage:</term>
3790 <screen>+delay-response{100}</screen>
3797 <!-- ~~~~~ New section ~~~~~ -->
3798 <sect3 renderas="sect4" id="downgrade-http-version">
3799 <title>downgrade-http-version</title>
3803 <term>Typical use:</term>
3805 <para>Work around (very rare) problems with HTTP/1.1</para>
3810 <term>Effect:</term>
3813 Downgrades HTTP/1.1 client requests and server replies to HTTP/1.0.
3820 <!-- boolean, parameterized, Multi-value -->
3822 <para>Boolean.</para>
3827 <term>Parameter:</term>
3839 This is a left-over from the time when <application>Privoxy</application>
3840 didn't support important HTTP/1.1 features well. It is left here for the
3841 unlikely case that you experience HTTP/1.1-related problems with some server
3845 Note that enabling this action is only a workaround. It should not
3846 be enabled for sites that work without it. While it shouldn't break
3847 any pages, it has an (usually negative) performance impact.
3850 If you come across a site where enabling this action helps, please report it,
3851 so the cause of the problem can be analyzed. If the problem turns out to be
3852 caused by a bug in <application>Privoxy</application> it should be
3853 fixed so the following release works without the work around.
3859 <term>Example usage (section):</term>
3861 <screen>{+downgrade-http-version}
3862 problem-host.example.com</screen>
3870 <!-- ~~~~~ New section ~~~~~ -->
3871 <sect3 renderas="sect4" id="external-filter">
3872 <title>external-filter</title>
3876 <term>Typical use:</term>
3878 <para>Modify content using a programming language of your choice.</para>
3883 <term>Effect:</term>
3886 All instances of text-based type, most notably HTML and JavaScript, to which
3887 this action applies, can be filtered on-the-fly through the specified external
3889 By default plain text documents are exempted from filtering, because web
3890 servers often use the <literal>text/plain</literal> MIME type for all files
3891 whose type they don't know.)
3898 <!-- boolean, parameterized, Multi-value -->
3900 <para>Multi-value.</para>
3905 <term>Parameter:</term>
3908 The name of an external content filter, as defined in the
3909 <link linkend="filter-file">filter file</link>.
3910 External filters can be defined in one or more files as defined by the
3911 <literal><link linkend="filterfile">filterfile</link></literal>
3912 option in the <link linkend="config">config file</link>.
3915 When used in its negative form,
3916 and without parameters, <emphasis>all</emphasis> filtering with external
3917 filters is completely disabled.
3926 External filters are scripts or programs that can modify the content in
3927 case common <literal><link linkend="filter">filters</link></literal>
3928 aren't powerful enough. With the exception that this action doesn't
3929 use pcrs-based filters, the notes in the
3930 <literal><link linkend="filter">filter</link></literal> section apply.
3934 Currently external filters are executed with &my-app;'s privileges.
3935 Only use external filters you understand and trust.
3939 This feature is experimental, the <literal><link
3940 linkend="external-filter-syntax">syntax</link></literal>
3941 may change in the future.
3948 <term>Example usage:</term>
3950 <screen>+external-filter{fancy-filter}</screen>
3956 <!-- ~~~~~ New section ~~~~~ -->
3957 <sect3 renderas="sect4" id="fast-redirects">
3958 <title>fast-redirects</title>
3962 <term>Typical use:</term>
3964 <para>Fool some click-tracking scripts and speed up indirect links.</para>
3969 <term>Effect:</term>
3972 Detects redirection URLs and redirects the browser without contacting
3973 the redirection server first.
3980 <!-- boolean, parameterized, Multi-value -->
3982 <para>Parameterized.</para>
3987 <term>Parameter:</term>
3992 <quote>simple-check</quote> to just search for the string <quote>http://</quote>
3993 to detect redirection URLs.
3998 <quote>check-decoded-url</quote> to decode URLs (if necessary) before searching
3999 for redirection URLs.
4010 Many sites, like yahoo.com, don't just link to other sites. Instead, they
4011 will link to some script on their own servers, giving the destination as a
4012 parameter, which will then redirect you to the final target. URLs
4013 resulting from this scheme typically look like:
4014 <quote>http://www.example.org/click-tracker.cgi?target=http%3a//www.example.net/</quote>.
4017 Sometimes, there are even multiple consecutive redirects encoded in the
4018 URL. These redirections via scripts make your web browsing more traceable,
4019 since the server from which you follow such a link can see where you go
4020 to. Apart from that, valuable bandwidth and time is wasted, while your
4021 browser asks the server for one redirect after the other. Plus, it feeds
4025 This feature is currently not very smart and is scheduled for improvement.
4026 If it is enabled by default, you will have to create some exceptions to
4027 this action. It can lead to failures in several ways:
4030 Not every URLs with other URLs as parameters is evil.
4031 Some sites offer a real service that requires this information to work.
4032 For example a validation service needs to know, which document to validate.
4033 <literal>fast-redirects</literal> assumes that every URL parameter that
4034 looks like another URL is a redirection target, and will always redirect to
4035 the last one. Most of the time the assumption is correct, but if it isn't,
4036 the user gets redirected anyway.
4039 Another failure occurs if the URL contains other parameters after the URL parameter.
4041 <quote>http://www.example.org/?redirect=http%3a//www.example.net/&foo=bar</quote>.
4042 contains the redirection URL <quote>http://www.example.net/</quote>,
4043 followed by another parameter. <literal>fast-redirects</literal> doesn't know that
4044 and will cause a redirect to <quote>http://www.example.net/&foo=bar</quote>.
4045 Depending on the target server configuration, the parameter will be silently ignored
4046 or lead to a <quote>page not found</quote> error. You can prevent this problem by
4047 first using the <literal><link linkend="redirect">redirect</link></literal> action
4048 to remove the last part of the URL, but it requires a little effort.
4051 To detect a redirection URL, <literal>fast-redirects</literal> only
4052 looks for the string <quote>http://</quote>, either in plain text
4053 (invalid but often used) or encoded as <quote>http%3a//</quote>.
4054 Some sites use their own URL encoding scheme, encrypt the address
4055 of the target server or replace it with a database id. In these cases
4056 <literal>fast-redirects</literal> is fooled and the request reaches the
4057 redirection server where it probably gets logged.
4063 <term>Example usage:</term>
4066 { +fast-redirects{simple-check} }
4069 { +fast-redirects{check-decoded-url} }
4070 another.example.com/testing</screen>
4078 <!-- ~~~~~ New section ~~~~~ -->
4079 <sect3 renderas="sect4" id="filter">
4080 <title>filter</title>
4084 <term>Typical use:</term>
4086 <para>Get rid of HTML and JavaScript annoyances, banner advertisements (by size),
4087 do fun text replacements, add personalized effects, etc.</para>
4092 <term>Effect:</term>
4095 All instances of text-based type, most notably HTML and JavaScript, to which
4096 this action applies, can be filtered on-the-fly through the specified regular
4097 expression based substitutions. (Note: as of version 3.0.3 plain text documents
4098 are exempted from filtering, because web servers often use the
4099 <literal>text/plain</literal> MIME type for all files whose type they don't know.)
4106 <!-- boolean, parameterized, Multi-value -->
4108 <para>Multi-value.</para>
4113 <term>Parameter:</term>
4116 The name of a content filter, as defined in the <link linkend="filter-file">filter file</link>.
4117 Filters can be defined in one or more files as defined by the
4118 <literal><link linkend="filterfile">filterfile</link></literal>
4119 option in the <link linkend="config">config file</link>.
4120 <filename>default.filter</filename> is the collection of filters
4121 supplied by the developers. Locally defined filters should go
4122 in their own file, such as <filename>user.filter</filename>.
4125 When used in its negative form,
4126 and without parameters, <emphasis>all</emphasis> filtering is completely disabled.
4135 For your convenience, there are a number of pre-defined filters available
4136 in the distribution filter file that you can use. See the examples below for
4140 Filtering requires buffering the page content, which may appear to
4141 slow down page rendering since nothing is displayed until all content has
4142 passed the filters. (The total time until the page is completely rendered
4143 doesn't change much, but it may be perceived as slower since the page is
4144 not incrementally displayed.)
4145 This effect will be more noticeable on slower connections.
4148 <quote>Rolling your own</quote>
4149 filters requires a knowledge of
4150 <ulink url="https://en.wikipedia.org/wiki/Regular_expressions"><quote>Regular
4151 Expressions</quote></ulink> and
4152 <ulink url="https://en.wikipedia.org/wiki/Html"><quote>HTML</quote></ulink>.
4153 This is very powerful feature, and potentially very intrusive.
4154 Filters should be used with caution, and where an equivalent
4155 <quote>action</quote> is not available.
4158 The amount of data that can be filtered is limited by the
4159 <literal><link linkend="buffer-limit">buffer-limit</link></literal>
4160 option in the main <link linkend="config">config file</link>. The
4161 default is 4096 KB (4 Megs). Once this limit is exceeded, the buffered
4162 data, and all pending data, is passed through unfiltered.
4165 Inappropriate MIME types, such as zipped files, are not filtered at all.
4166 (Again, only text-based types except plain text). Encrypted SSL data
4167 (from HTTPS servers) cannot be filtered either, since this would violate
4168 the integrity of the secure transaction. In some situations it might
4169 be necessary to protect certain text, like source code, from filtering
4170 by defining appropriate <literal>-filter</literal> exceptions.
4173 Compressed content can't be filtered either, but if &my-app;
4174 is compiled with zlib support and a supported compression algorithm
4175 is used (gzip or deflate), &my-app; can first decompress the content
4179 If you use a &my-app; version without zlib support, but want filtering to work on
4180 as much documents as possible, even those that would normally be sent compressed,
4181 you must use the <literal><link linkend="prevent-compression">prevent-compression</link></literal>
4182 action in conjunction with <literal>filter</literal>.
4185 Content filtering can achieve some of the same effects as the
4186 <literal><link linkend="block">block</link></literal>
4187 action, i.e. it can be used to block ads and banners. But the mechanism
4188 works quite differently. One effective use, is to block ad banners
4189 based on their size (see below), since many of these seem to be somewhat
4193 <link linkend="contact">Feedback</link> with suggestions for new or
4194 improved filters is particularly welcome!
4197 The below list has only the names and a one-line description of each
4198 predefined filter. There are <link linkend="predefined-filters">more
4199 verbose explanations</link> of what these filters do in the <link
4200 linkend="filter-file">filter file chapter</link>.
4206 <term>Example usage (with filters from the distribution <filename>default.filter</filename> file).
4207 See <link linkend="PREDEFINED-FILTERS">the Predefined Filters section</link> for
4208 more explanation on each:</term>
4211 <anchor id="filter-js-annoyances">
4213 <screen>+filter{js-annoyances} # Get rid of particularly annoying JavaScript abuse.</screen>
4215 <anchor id="filter-js-events">
4217 <screen>+filter{js-events} # Kill JavaScript event bindings and timers (Radically destructive! Only for extra nasty sites).</screen>
4219 <anchor id="filter-html-annoyances">
4221 <screen>+filter{html-annoyances} # Get rid of particularly annoying HTML abuse.</screen>
4223 <anchor id="filter-content-cookies">
4225 <screen>+filter{content-cookies} # Kill cookies that come in the HTML or JS content.</screen>
4227 <anchor id="filter-refresh-tags">
4229 <screen>+filter{refresh-tags} # Kill automatic refresh tags if refresh time is larger than 9 seconds.</screen>
4231 <anchor id="filter-unsolicited-popups">
4233 <screen>+filter{unsolicited-popups} # Disable only unsolicited pop-up windows.</screen>
4235 <anchor id="filter-all-popups">
4237 <screen>+filter{all-popups} # Kill all popups in JavaScript and HTML.</screen>
4239 <anchor id="filter-img-reorder">
4241 <screen>+filter{img-reorder} # Reorder attributes in <img> tags to make the banners-by-* filters more effective.</screen>
4243 <anchor id="filter-banners-by-size">
4245 <screen>+filter{banners-by-size} # Kill banners by size.</screen>
4247 <anchor id="filter-banners-by-link">
4249 <screen>+filter{banners-by-link} # Kill banners by their links to known clicktrackers.</screen>
4251 <anchor id="filter-webbugs">
4253 <screen>+filter{webbugs} # Squish WebBugs (1x1 invisible GIFs used for user tracking).</screen>
4255 <anchor id="filter-tiny-textforms">
4257 <screen>+filter{tiny-textforms} # Extend those tiny textareas up to 40x80 and kill the hard wrap.</screen>
4259 <anchor id="filter-jumping-windows">
4261 <screen>+filter{jumping-windows} # Prevent windows from resizing and moving themselves.</screen>
4263 <anchor id="filter-frameset-borders">
4265 <screen>+filter{frameset-borders} # Give frames a border and make them resizable.</screen>
4267 <anchor id="filter-iframes">
4269 <screen>+filter{iframes} # Removes all detected iframes. Should only be enabled for individual sites.</screen>
4271 <anchor id="filter-demoronizer">
4273 <screen>+filter{demoronizer} # Fix MS's non-standard use of standard charsets.</screen>
4275 <anchor id="filter-shockwave-flash">
4277 <screen>+filter{shockwave-flash} # Kill embedded Shockwave Flash objects.</screen>
4279 <anchor id="filter-quicktime-kioskmode">
4281 <screen>+filter{quicktime-kioskmode} # Make Quicktime movies saveable.</screen>
4283 <anchor id="filter-fun">
4285 <screen>+filter{fun} # Text replacements for subversive browsing fun!</screen>
4287 <anchor id="filter-crude-parental">
4289 <screen>+filter{crude-parental} # Crude parental filtering. Note that this filter doesn't work reliably.</screen>
4291 <anchor id="filter-ie-exploits">
4293 <screen>+filter{ie-exploits} # Disable some known Internet Explorer bug exploits.</screen>
4295 <anchor id="filter-site-specifics">
4297 <screen>+filter{site-specifics} # Cure for site-specific problems. Don't apply generally!</screen>
4299 <anchor id="filter-no-ping">
4301 <screen>+filter{no-ping} # Removes non-standard ping attributes in <a> and <area> tags.</screen>
4303 <anchor id="filter-github">
4305 <screen>+filter{github} # Removes the annoying "Sign-Up" banner and the Cookie disclaimer.</screen>
4307 <anchor id="filter-google">
4309 <screen>+filter{google} # CSS-based block for Google text ads. Also removes a width limitation and the toolbar advertisement.</screen>
4311 <anchor id="filter-imdb">
4313 <screen>+filter{imdb} # Removes some ads on IMDb.</screen>
4315 <anchor id="filter-yahoo">
4317 <screen>+filter{yahoo} # CSS-based block for Yahoo text ads. Also removes a width limitation.</screen>
4319 <anchor id="filter-msn">
4321 <screen>+filter{msn} # CSS-based block for MSN text ads. Also removes tracking URLs and a width limitation.</screen>
4323 <anchor id="filter-blogspot">
4325 <screen>+filter{blogspot} # Cleans up some Blogspot blogs. Read the fine print before using this.</screen>
4327 <anchor id="filter-sourceforge">
4329 <screen>+filter{sourceforge} # Reduces the amount of ads for proprietary software on SourceForge.</screen>
4336 <!-- ~~~~~ New section ~~~~~ -->
4337 <sect3 renderas="sect4" id="force-text-mode">
4338 <title>force-text-mode</title>
4344 <term>Typical use:</term>
4346 <para>Force <application>Privoxy</application> to treat a document as if it was in some kind of <emphasis>text</emphasis> format. </para>
4351 <term>Effect:</term>
4354 Declares a document as text, even if the <quote>Content-Type:</quote> isn't detected as such.
4361 <!-- Boolean, Parameterized, Multi-value -->
4363 <para>Boolean.</para>
4368 <term>Parameter:</term>
4380 As explained <literal><link linkend="filter">above</link></literal>,
4381 <application>Privoxy</application> tries to only filter files that are
4382 in some kind of text format. The same restrictions apply to
4383 <literal><link linkend="content-type-overwrite">content-type-overwrite</link></literal>.
4384 <literal>force-text-mode</literal> declares a document as text,
4385 without looking at the <quote>Content-Type:</quote> first.
4389 Think twice before activating this action. Filtering binary data
4390 with regular expressions can cause file damage.
4397 <term>Example usage:</term>
4408 <!-- ~~~~~ New section ~~~~~ -->
4409 <sect3 renderas="sect4" id="forward-override">
4410 <title>forward-override</title>
4416 <term>Typical use:</term>
4418 <para>Change the forwarding settings based on User-Agent or request origin</para>
4423 <term>Effect:</term>
4426 Overrules the forward directives in the configuration file.
4433 <!-- Boolean, Parameterized, Multi-value -->
4435 <para>Parameterized.</para>
4440 <term>Parameter:</term>
4444 <para><quote>forward .</quote> to use a direct connection without any additional proxies.</para>
4448 <quote>forward 127.0.0.1:8123</quote> to use the HTTP proxy listening at 127.0.0.1 port 8123.
4453 <quote>forward-socks4a 127.0.0.1:9050 .</quote> to use the socks4a proxy listening at
4454 127.0.0.1 port 9050. Replace <quote>forward-socks4a</quote> with <quote>forward-socks4</quote>
4455 to use a socks4 connection (with local DNS resolution) instead, use <quote>forward-socks5</quote>
4456 for socks5 connections (with remote DNS resolution).
4461 <quote>forward-socks4a 127.0.0.1:9050 proxy.example.org:8000</quote> to use the socks4a proxy
4462 listening at 127.0.0.1 port 9050 to reach the HTTP proxy listening at proxy.example.org port 8000.
4463 Replace <quote>forward-socks4a</quote> with <quote>forward-socks4</quote> to use a socks4 connection
4464 (with local DNS resolution) instead, use <quote>forward-socks5</quote>
4465 for socks5 connections (with remote DNS resolution).
4470 <quote>forward-webserver 127.0.0.1:80</quote> to use the HTTP
4471 server listening at 127.0.0.1 port 80 without adjusting the
4475 This makes it more convenient to use Privoxy to make
4476 existing websites available as onion services as well.
4479 Many websites serve content with hardcoded URLs and
4480 can't be easily adjusted to change the domain based
4481 on the one used by the client.
4484 Putting Privoxy between Tor and the webserver (or an stunnel
4485 that forwards to the webserver) allows to rewrite headers and
4486 content to make client and server happy at the same time.
4489 Using Privoxy for webservers that are only reachable through
4490 onion addresses and whose location is supposed to be secret
4491 is not recommended and should not be necessary anyway.
4502 This action takes parameters similar to the
4503 <link linkend="forwarding">forward</link> directives in the configuration
4504 file, but without the URL pattern. It can be used as replacement, but normally it's only
4505 used in cases where matching based on the request URL isn't sufficient.
4509 Please read the description for the <link linkend="forwarding">forward</link> directives before
4510 using this action. Forwarding to the wrong people will reduce your privacy and increase the
4511 chances of man-in-the-middle attacks.
4514 If the ports are missing or invalid, default values will be used. This might change
4515 in the future and you shouldn't rely on it. Otherwise incorrect syntax causes Privoxy
4516 to exit. Due to design limitations, invalid parameter syntax isn't detected until the
4517 action is used the first time.
4520 Use the <ulink url="http://config.privoxy.org/show-url-info">show-url-info CGI page</ulink>
4521 to verify that your forward settings do what you thought the do.
4528 <term>Example usage:</term>
4531 # Use an ssh tunnel for requests previously tagged as
4532 # <quote>User-Agent: fetch libfetch/2.0</quote> and make sure
4533 # resuming downloads continues to work.
4535 # This way you can continue to use Tor for your normal browsing,
4536 # without overloading the Tor network with your FreeBSD ports updates
4537 # or downloads of bigger files like ISOs.
4539 # Note that HTTP headers are easy to fake and therefore their
4540 # values are as (un)trustworthy as your clients and users.
4541 {+forward-override{forward-socks5 10.0.0.2:2222 .} \
4542 -hide-if-modified-since \
4543 -overwrite-last-modified \
4545 TAG:^User-Agent: fetch libfetch/2\.0$
4553 <!-- ~~~~~ New section ~~~~~ -->
4554 <sect3 renderas="sect4" id="handle-as-empty-document">
4555 <title>handle-as-empty-document</title>
4561 <term>Typical use:</term>
4563 <para>Mark URLs that should be replaced by empty documents <emphasis>if they get blocked</emphasis></para>
4568 <term>Effect:</term>
4571 This action alone doesn't do anything noticeable. It just marks URLs.
4572 If the <literal><link linkend="block">block</link></literal> action <emphasis>also applies</emphasis>,
4573 the presence or absence of this mark decides whether an HTML <quote>BLOCKED</quote>
4574 page, or an empty document will be sent to the client as a substitute for the blocked content.
4575 The <emphasis>empty</emphasis> document isn't literally empty, but actually contains a single space.
4582 <!-- Boolean, Parameterized, Multi-value -->
4584 <para>Boolean.</para>
4589 <term>Parameter:</term>
4601 Some browsers complain about syntax errors if JavaScript documents
4602 are blocked with <application>Privoxy's</application>
4603 default HTML page; this option can be used to silence them.
4604 And of course this action can also be used to eliminate the &my-app;
4605 BLOCKED message in frames.
4608 The content type for the empty document can be specified with
4609 <literal><link linkend="content-type-overwrite">content-type-overwrite{}</link></literal>,
4610 but usually this isn't necessary.
4616 <term>Example usage:</term>
4618 <screen># Block all documents on example.org that end with ".js",
4619 # but send an empty document instead of the usual HTML message.
4620 {+block{Blocked JavaScript} +handle-as-empty-document}
4629 <!-- ~~~~~ New section ~~~~~ -->
4630 <sect3 renderas="sect4" id="handle-as-image">
4631 <title>handle-as-image</title>
4635 <term>Typical use:</term>
4637 <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>
4642 <term>Effect:</term>
4645 This action alone doesn't do anything noticeable. It just marks URLs as images.
4646 If the <literal><link linkend="block">block</link></literal> action <emphasis>also applies</emphasis>,
4647 the presence or absence of this mark decides whether an HTML <quote>blocked</quote>
4648 page, or a replacement image (as determined by the <literal><link
4649 linkend="set-image-blocker">set-image-blocker</link></literal> action) will be sent to the
4650 client as a substitute for the blocked content.
4657 <!-- Boolean, Parameterized, Multi-value -->
4659 <para>Boolean.</para>
4664 <term>Parameter:</term>
4676 The below generic example section is actually part of <filename>default.action</filename>.
4677 It marks all URLs with well-known image file name extensions as images and should
4681 Users will probably only want to use the handle-as-image action in conjunction with
4682 <literal><link linkend="block">block</link></literal>, to block sources of banners, whose URLs don't
4683 reflect the file type, like in the second example section.
4686 Note that you cannot treat HTML pages as images in most cases. For instance, (in-line) ad
4687 frames require an HTML page to be sent, or they won't display properly.
4688 Forcing <literal>handle-as-image</literal> in this situation will not replace the
4689 ad frame with an image, but lead to error messages.
4695 <term>Example usage (sections):</term>
4697 <screen># Generic image extensions:
4700 /.*\.(gif|jpg|jpeg|png|bmp|ico)$
4702 # These don't look like images, but they're banners and should be
4703 # blocked as images:
4705 {+block{Nasty banners.} +handle-as-image}
4706 nasty-banner-server.example.com/junk.cgi\?output=trash
4714 <!-- ~~~~~ New section ~~~~~ -->
4715 <sect3 renderas="sect4" id="hide-accept-language">
4716 <title>hide-accept-language</title>
4722 <term>Typical use:</term>
4724 <para>Pretend to use different language settings.</para>
4729 <term>Effect:</term>
4732 Deletes or replaces the <quote>Accept-Language:</quote> HTTP header in client requests.
4739 <!-- Boolean, Parameterized, Multi-value -->
4741 <para>Parameterized.</para>
4746 <term>Parameter:</term>
4749 Keyword: <quote>block</quote>, or any user defined value.
4758 Faking the browser's language settings can be useful to make a
4759 foreign User-Agent set with
4760 <literal><link linkend="hide-user-agent">hide-user-agent</link></literal>
4764 However some sites with content in different languages check the
4765 <quote>Accept-Language:</quote> to decide which one to take by default.
4766 Sometimes it isn't possible to later switch to another language without
4767 changing the <quote>Accept-Language:</quote> header first.
4770 Therefore it's a good idea to either only change the
4771 <quote>Accept-Language:</quote> header to languages you understand,
4772 or to languages that aren't wide spread.
4775 Before setting the <quote>Accept-Language:</quote> header
4776 to a rare language, you should consider that it helps to
4777 make your requests unique and thus easier to trace.
4778 If you don't plan to change this header frequently,
4779 you should stick to a common language.
4785 <term>Example usage (section):</term>
4787 <screen># Pretend to use Canadian language settings.
4788 {+hide-accept-language{en-ca} \
4789 +hide-user-agent{Mozilla/5.0 (X11; U; OpenBSD i386; en-CA; rv:1.8.0.4) Gecko/20060628 Firefox/1.5.0.4} \
4799 <!-- ~~~~~ New section ~~~~~ -->
4800 <sect3 renderas="sect4" id="hide-content-disposition">
4801 <title>hide-content-disposition</title>
4807 <term>Typical use:</term>
4809 <para>Prevent download menus for content you prefer to view inside the browser.</para>
4814 <term>Effect:</term>
4817 Deletes or replaces the <quote>Content-Disposition:</quote> HTTP header set by some servers.
4824 <!-- Boolean, Parameterized, Multi-value -->
4826 <para>Parameterized.</para>
4831 <term>Parameter:</term>
4834 Keyword: <quote>block</quote>, or any user defined value.
4843 Some servers set the <quote>Content-Disposition:</quote> HTTP header for
4844 documents they assume you want to save locally before viewing them.
4845 The <quote>Content-Disposition:</quote> header contains the file name
4846 the browser is supposed to use by default.
4849 In most browsers that understand this header, it makes it impossible to
4850 <emphasis>just view</emphasis> the document, without downloading it first,
4851 even if it's just a simple text file or an image.
4854 Removing the <quote>Content-Disposition:</quote> header helps
4855 to prevent this annoyance, but some browsers additionally check the
4856 <quote>Content-Type:</quote> header, before they decide if they can
4857 display a document without saving it first. In these cases, you have
4858 to change this header as well, before the browser stops displaying
4862 It is also possible to change the server's file name suggestion
4863 to another one, but in most cases it isn't worth the time to set
4867 This action will probably be removed in the future,
4868 use server-header filters instead.
4874 <term>Example usage:</term>
4876 <screen># Disarm the download link in Sourceforge's patch tracker
4878 +content-type-overwrite{text/plain}\
4879 +hide-content-disposition{block} }
4880 .sourceforge.net/tracker/download\.php</screen>
4887 <!-- ~~~~~ New section ~~~~~ -->
4888 <sect3 renderas="sect4" id="hide-if-modified-since">
4889 <title>hide-if-modified-since</title>
4895 <term>Typical use:</term>
4897 <para>Prevent yet another way to track the user's steps between sessions.</para>
4902 <term>Effect:</term>
4905 Deletes the <quote>If-Modified-Since:</quote> HTTP client header or modifies its value.
4912 <!-- Boolean, Parameterized, Multi-value -->
4914 <para>Parameterized.</para>
4919 <term>Parameter:</term>
4922 Keyword: <quote>block</quote>, or a user defined value that specifies a range of hours.
4931 Removing this header is useful for filter testing, where you want to force a real
4932 reload instead of getting status code <quote>304</quote>, which would cause the
4933 browser to use a cached copy of the page.
4936 Instead of removing the header, <literal>hide-if-modified-since</literal> can
4937 also add or subtract a random amount of time to/from the header's value.
4938 You specify a range of minutes where the random factor should be chosen from and
4939 <application>Privoxy</application> does the rest. A negative value means
4940 subtracting, a positive value adding.
4943 Randomizing the value of the <quote>If-Modified-Since:</quote> makes
4944 it less likely that the server can use the time as a cookie replacement,
4945 but you will run into caching problems if the random range is too high.
4948 It is a good idea to only use a small negative value and let
4949 <literal><link linkend="overwrite-last-modified">overwrite-last-modified</link></literal>
4950 handle the greater changes.
4953 It is also recommended to use this action together with
4954 <literal><link linkend="crunch-if-none-match">crunch-if-none-match</link></literal>,
4955 otherwise it's more or less pointless.
4961 <term>Example usage (section):</term>
4963 <screen># Let the browser revalidate but make tracking based on the time less likely.
4964 {+hide-if-modified-since{-60} \
4965 +overwrite-last-modified{randomize} \
4966 +crunch-if-none-match}
4974 <!-- ~~~~~ New section ~~~~~ -->
4975 <sect3 renderas="sect4" id="hide-from-header">
4976 <title>hide-from-header</title>
4980 <term>Typical use:</term>
4982 <para>Keep your (old and ill) browser from telling web servers your email address</para>
4987 <term>Effect:</term>
4990 Deletes any existing <quote>From:</quote> HTTP header, or replaces it with the
4998 <!-- Boolean, Parameterized, Multi-value -->
5000 <para>Parameterized.</para>
5005 <term>Parameter:</term>
5008 Keyword: <quote>block</quote>, or any user defined value.
5017 The keyword <quote>block</quote> will completely remove the header
5018 (not to be confused with the <literal><link linkend="block">block</link></literal>
5022 Alternately, you can specify any value you prefer to be sent to the web
5023 server. If you do, it is a matter of fairness not to use any address that
5024 is actually used by a real person.
5027 This action is rarely needed, as modern web browsers don't send
5028 <quote>From:</quote> headers anymore.
5034 <term>Example usage:</term>
5036 <screen>+hide-from-header{block}</screen>
5038 <screen>+hide-from-header{spam-me-senseless@sittingduck.example.com}</screen>
5045 <!-- ~~~~~ New section ~~~~~ -->
5046 <sect3 renderas="sect4" id="hide-referrer">
5047 <title>hide-referrer</title>
5048 <anchor id="hide-referer">
5051 <term>Typical use:</term>
5053 <para>Conceal which link you followed to get to a particular site</para>
5058 <term>Effect:</term>
5061 Deletes the <quote>Referer:</quote> (sic) HTTP header from the client request,
5062 or replaces it with a forged one.
5069 <!-- Boolean, Parameterized, Multi-value -->
5071 <para>Parameterized.</para>
5076 <term>Parameter:</term>
5080 <para><quote>conditional-block</quote> to delete the header completely if the host has changed.</para>
5083 <para><quote>conditional-forge</quote> to forge the header if the host has changed.</para>
5086 <para><quote>block</quote> to delete the header unconditionally.</para>
5089 <para><quote>forge</quote> to pretend to be coming from the homepage of the server we are talking to.</para>
5092 <para>Any other string to set a user defined referrer.</para>
5102 <literal>conditional-block</literal> is the only parameter,
5103 that isn't easily detected in the server's log file. If it blocks the
5104 referrer, the request will look like the visitor used a bookmark or
5105 typed in the address directly.
5108 Leaving the referrer unmodified for requests on the same host
5109 allows the server owner to see the visitor's <quote>click path</quote>,
5110 but in most cases she could also get that information by comparing
5111 other parts of the log file: for example the User-Agent if it isn't
5112 a very common one, or the user's IP address if it doesn't change between
5116 Always blocking the referrer, or using a custom one, can lead to
5117 failures on servers that check the referrer before they answer any
5118 requests, in an attempt to prevent their content from being
5119 embedded or linked to elsewhere.
5122 Both <literal>conditional-block</literal> and <literal>forge</literal>
5123 will work with referrer checks, as long as content and valid referring page
5124 are on the same host. Most of the time that's the case.
5127 <literal>hide-referer</literal> is an alternate spelling of
5128 <literal>hide-referrer</literal> and the two can be can be freely
5129 substituted with each other. (<quote>referrer</quote> is the
5130 correct English spelling, however the HTTP specification has a bug - it
5131 requires it to be spelled as <quote>referer</quote>.)
5137 <term>Example usage:</term>
5139 <screen>+hide-referrer{forge}</screen>
5141 <screen>+hide-referrer{http://www.yahoo.com/}</screen>
5148 <!-- ~~~~~ New section ~~~~~ -->
5149 <sect3 renderas="sect4" id="hide-user-agent">
5150 <title>hide-user-agent</title>
5154 <term>Typical use:</term>
5156 <para>Try to conceal your type of browser and client operating system</para>
5161 <term>Effect:</term>
5164 Replaces the value of the <quote>User-Agent:</quote> HTTP header
5165 in client requests with the specified value.
5172 <!-- Boolean, Parameterized, Multi-value -->
5174 <para>Parameterized.</para>
5179 <term>Parameter:</term>
5182 Any user-defined string.
5192 This can lead to problems on web sites that depend on looking at this header in
5193 order to customize their content for different browsers (which, by the
5194 way, is <emphasis>NOT</emphasis> the right thing to do: good web sites
5195 work browser-independently).
5199 Using this action in multi-user setups or wherever different types of
5200 browsers will access the same <application>Privoxy</application> is
5201 <emphasis>not recommended</emphasis>. In single-user, single-browser
5202 setups, you might use it to delete your OS version information from
5203 the headers, because it is an invitation to exploit known bugs for your
5204 OS. It is also occasionally useful to forge this in order to access
5205 sites that won't let you in otherwise (though there may be a good
5206 reason in some cases).
5209 More information on known user-agent strings can be found at
5210 <ulink url="http://www.user-agents.org/">http://www.user-agents.org/</ulink>
5212 <ulink url="https://en.wikipedia.org/wiki/User_agent">http://en.wikipedia.org/wiki/User_agent</ulink>.
5218 <term>Example usage:</term>
5220 <screen>+hide-user-agent{Mozilla/5.0 (X11; ElectroBSD i386; rv:78.0) Gecko/20100101 Firefox/78.0}</screen>
5227 <!-- ~~~~~ New section ~~~~~ -->
5228 <sect3 renderas="sect4" id="https-inspection">
5229 <title>https-inspection</title>
5233 <term>Typical use:</term>
5235 <para>Filter encrypted requests and responses</para>
5240 <term>Effect:</term>
5243 Encrypted requests are decrypted, filtered and forwarded encrypted.
5250 <!-- boolean, parameterized, Multi-value -->
5252 <para>Boolean.</para>
5257 <term>Parameter:</term>
5269 This action allows &my-app; to filter encrypted requests and responses.
5270 For this to work &my-app; has to generate a certificate and send it
5271 to the client which has to accept it.
5274 Before this works the directives in the
5275 <literal><ulink url="config.html#HTTPS-INSPECTION-DIRECTIVES">HTTPS inspection section</ulink></literal>
5276 of the config file have to be configured.
5279 Note that the action has to be enabled based on the CONNECT
5280 request which doesn't contain a path. Enabling it based on
5281 a pattern with path doesn't work as the path is only seen
5282 by &my-app; if the action is already enabled.
5285 This is an experimental feature.
5291 <term>Example usage (section):</term>
5293 <screen>{+https-inspection}
5294 www.example.com</screen>
5302 <!-- ~~~~~ New section ~~~~~ -->
5303 <sect3 renderas="sect4" id="ignore-certificate-errors">
5304 <title>ignore-certificate-errors</title>
5308 <term>Typical use:</term>
5310 <para>Filter encrypted requests and responses without verifying the certificate</para>
5315 <term>Effect:</term>
5318 Encrypted requests are forwarded to sites without verifying the certificate.
5325 <!-- Boolean, Parameterized, Multi-value -->
5327 <para>Boolean.</para>
5332 <term>Parameter:</term>
5345 <link linkend="HTTPS-INSPECTION"><quote>+https-inspection</quote></link>
5346 action is used &my-app; by default verifies that the remote site uses a valid
5350 If the certificate can't be validated by &my-app; the connection is aborted.
5353 This action disables the certificate check so requests to sites
5354 with certificates that can't be validated are allowed.
5357 Note that enabling this action allows Man-in-the-middle attacks.
5363 <term>Example usage:</term>
5366 {+ignore-certificate-errors}
5375 <!-- ~~~~~ New section ~~~~~ -->
5376 <sect3 renderas="sect4" id="limit-connect">
5377 <title>limit-connect</title>
5381 <term>Typical use:</term>
5383 <para>Prevent abuse of <application>Privoxy</application> as a TCP proxy relay or disable SSL for untrusted sites</para>
5388 <term>Effect:</term>
5391 Specifies to which ports HTTP CONNECT requests are allowable.
5398 <!-- Boolean, Parameterized, Multi-value -->
5400 <para>Parameterized.</para>
5405 <term>Parameter:</term>
5408 A comma-separated list of ports or port ranges (the latter using dashes, with the minimum
5409 defaulting to 0 and the maximum to 65K).
5418 By default, i.e. if no <literal>limit-connect</literal> action applies,
5419 <application>Privoxy</application> allows HTTP CONNECT requests to all
5420 ports. Use <literal>limit-connect</literal> if fine-grained control
5421 is desired for some or all destinations.
5424 The CONNECT methods exists in HTTP to allow access to secure websites
5425 (<quote>https://</quote> URLs) through proxies. It works very simply:
5426 the proxy connects to the server on the specified port, and then
5427 short-circuits its connections to the client and to the remote server.
5428 This means CONNECT-enabled proxies can be used as TCP relays very easily.
5431 <application>Privoxy</application> relays HTTPS traffic without seeing
5432 the decoded content. Websites can leverage this limitation to circumvent &my-app;'s
5433 filters. By specifying an invalid port range you can disable HTTPS entirely.
5439 <term>Example usages:</term>
5441 <!-- I had trouble getting the spacing to look right in my browser -->
5442 <!-- I probably have the wrong font setup, bollocks. -->
5443 <!-- Apparently the emphasis tag uses a proportional font no matter what -->
5444 <screen>+limit-connect{443} # Port 443 is OK.
5445 +limit-connect{80,443} # Ports 80 and 443 are OK.
5446 +limit-connect{-3, 7, 20-100, 500-} # Ports less than 3, 7, 20 to 100 and above 500 are OK.
5447 +limit-connect{-} # All ports are OK
5448 +limit-connect{,} # No HTTPS/SSL traffic is allowed</screen>
5455 <!-- ~~~~~ New section ~~~~~ -->
5456 <sect3 renderas="sect4" id="limit-cookie-lifetime">
5457 <title>limit-cookie-lifetime</title>
5461 <term>Typical use:</term>
5463 <para>Limit the lifetime of HTTP cookies to a couple of minutes or hours.</para>
5468 <term>Effect:</term>
5471 Overwrites the expires field in Set-Cookie server headers if it's above the specified limit.
5478 <!-- Boolean, Parameterized, Multi-value -->
5480 <para>Parameterized.</para>
5485 <term>Parameter:</term>
5488 The lifetime limit in minutes, or 0.
5497 This action reduces the lifetime of HTTP cookies coming from the
5498 server to the specified number of minutes, starting from the time
5499 the cookie passes Privoxy.
5502 Cookies with a lifetime below the limit are not modified.
5503 The lifetime of session cookies is set to the specified limit.
5506 The effect of this action depends on the server.
5509 In case of servers which refresh their cookies with each response
5510 (or at least frequently), the lifetime limit set by this action
5512 Thus, a session associated with the cookie continues to work with
5513 this action enabled, as long as a new request is made before the
5514 last limit set is reached.
5517 However, some servers send their cookies once, with a lifetime of several
5518 years (the year 2037 is a popular choice), and do not refresh them
5519 until a certain event in the future, for example the user logging out.
5520 In this case this action may limit the absolute lifetime of the session,
5521 even if requests are made frequently.
5524 If the parameter is <quote>0</quote>, this action behaves like
5525 <literal><link linkend="session-cookies-only">session-cookies-only</link></literal>.
5531 <term>Example usages:</term>
5533 <screen>+limit-cookie-lifetime{60}</screen>
5539 <!-- ~~~~~ New section ~~~~~ -->
5540 <sect3 renderas="sect4" id="prevent-compression">
5541 <title>prevent-compression</title>
5545 <term>Typical use:</term>
5548 Ensure that servers send the content uncompressed, so it can be
5549 passed through <literal><link linkend="filter">filter</link></literal>s.
5555 <term>Effect:</term>
5558 Removes the Accept-Encoding header which can be used to ask for compressed transfer.
5565 <!-- Boolean, Parameterized, Multi-value -->
5567 <para>Boolean.</para>
5572 <term>Parameter:</term>
5584 More and more websites send their content compressed by default, which
5585 is generally a good idea and saves bandwidth. But the <literal><link
5586 linkend="filter">filter</link></literal> and
5587 <literal><link linkend="deanimate-gifs">deanimate-gifs</link></literal>
5588 actions need access to the uncompressed data.
5591 When compiled with zlib support (available since &my-app; 3.0.7), content that should be
5592 filtered is decompressed on-the-fly and you don't have to worry about this action.
5593 If you are using an older &my-app; version, or one that hasn't been compiled with zlib
5594 support, this action can be used to convince the server to send the content uncompressed.
5597 Most text-based instances compress very well, the size is seldom decreased by less than 50%,
5598 for markup-heavy instances like news feeds saving more than 90% of the original size isn't
5602 Not using compression will therefore slow down the transfer, and you should only
5603 enable this action if you really need it. As of &my-app; 3.0.7 it's disabled in all
5604 predefined action settings.
5607 Note that some (rare) ill-configured sites don't handle requests for uncompressed
5608 documents correctly. Broken PHP applications tend to send an empty document body,
5609 some IIS versions only send the beginning of the content and some content delivery
5610 networks let the connection time out.
5611 If you enable <literal>prevent-compression</literal> per default, you might
5612 want to add exceptions for those sites. See the example for how to do that.
5618 <term>Example usage (sections):</term>
5621 # Selectively turn off compression, and enable a filter
5623 { +filter{tiny-textforms} +prevent-compression }
5624 # Match only these sites
5629 # Or instead, we could set a universal default:
5631 { +prevent-compression }
5634 # Then maybe make exceptions for broken sites:
5636 { -prevent-compression }
5637 .compusa.com/</screen>
5645 <!-- ~~~~~ New section ~~~~~ -->
5646 <sect3 renderas="sect4" id="overwrite-last-modified">
5647 <title>overwrite-last-modified</title>
5653 <term>Typical use:</term>
5655 <para>Prevent yet another way to track the user's steps between sessions.</para>
5660 <term>Effect:</term>
5663 Deletes the <quote>Last-Modified:</quote> HTTP server header or modifies its value.
5670 <!-- Boolean, Parameterized, Multi-value -->
5672 <para>Parameterized.</para>
5677 <term>Parameter:</term>
5680 One of the keywords: <quote>block</quote>, <quote>reset-to-request-time</quote>
5681 and <quote>randomize</quote>
5690 Removing the <quote>Last-Modified:</quote> header is useful for filter
5691 testing, where you want to force a real reload instead of getting status
5692 code <quote>304</quote>, which would cause the browser to reuse the old
5693 version of the page.
5696 The <quote>randomize</quote> option overwrites the value of the
5697 <quote>Last-Modified:</quote> header with a randomly chosen time
5698 between the original value and the current time. In theory the server
5699 could send each document with a different <quote>Last-Modified:</quote>
5700 header to track visits without using cookies. <quote>Randomize</quote>
5701 makes it impossible and the browser can still revalidate cached documents.
5704 <quote>reset-to-request-time</quote> overwrites the value of the
5705 <quote>Last-Modified:</quote> header with the current time. You could use
5706 this option together with
5707 <literal><link linkend="hide-if-modified-since">hide-if-modified-since</link></literal>
5708 to further customize your random range.
5711 The preferred parameter here is <quote>randomize</quote>. It is safe
5712 to use, as long as the time settings are more or less correct.
5713 If the server sets the <quote>Last-Modified:</quote> header to the time
5714 of the request, the random range becomes zero and the value stays the same.
5715 Therefore you should later randomize it a second time with
5716 <literal><link linkend="hide-if-modified-since">hided-if-modified-since</link></literal>,
5720 It is also recommended to use this action together with
5721 <literal><link linkend="crunch-if-none-match">crunch-if-none-match</link></literal>.
5727 <term>Example usage:</term>
5729 <screen># Let the browser revalidate without being tracked across sessions
5730 { +hide-if-modified-since{-60} \
5731 +overwrite-last-modified{randomize} \
5732 +crunch-if-none-match}
5740 <!-- ~~~~~ New section ~~~~~ -->
5741 <sect3 renderas="sect4" id="redirect">
5742 <title>redirect</title>
5748 <term>Typical use:</term>
5751 Redirect requests to other sites.
5757 <term>Effect:</term>
5760 Convinces the browser that the requested document has been moved
5761 to another location and the browser should get it from there.
5768 <!-- Boolean, Parameterized, Multi-value -->
5770 <para>Parameterized</para>
5775 <term>Parameter:</term>
5778 An absolute URL or a single pcrs command.
5787 Requests to which this action applies are answered with a
5788 HTTP redirect to URLs of your choosing. The new URL is
5789 either provided as parameter, or derived by applying a
5790 single pcrs command to the original URL.
5793 The syntax for pcrs commands is documented in the
5794 <link linkend="filter-file">filter file</link> section.
5797 Requests can't be blocked and redirected at the same time,
5798 applying this action together with
5799 <literal><link linkend="block">block</link></literal>
5800 is a configuration error. Currently the request is blocked
5801 and an error message logged, the behavior may change in the
5802 future and result in Privoxy rejecting the action file.
5805 This action can be combined with
5806 <literal><link linkend="fast-redirects">fast-redirects{check-decoded-url}</link></literal>
5807 to redirect to a decoded version of a rewritten URL.
5810 Use this action carefully, make sure not to create redirection loops
5811 and be aware that using your own redirects might make it
5812 possible to fingerprint your requests.
5815 In case of problems with your redirects, or simply to watch
5816 them working, enable <link linkend="DEBUG">debug 128</link>.
5822 <term>Example usages:</term>
5824 <screen># Replace example.com's style sheet with another one
5825 { +redirect{http://localhost/css-replacements/example.com.css} }
5826 example.com/stylesheet\.css
5828 # Create a short, easy to remember nickname for a favorite site
5829 # (relies on the browser to accept and forward invalid URLs to &my-app;)
5830 { +redirect{https://www.privoxy.org/user-manual/actions-file.html} }
5833 # Always use the expanded view for Undeadly.org articles
5834 # (Note the $ at the end of the URL pattern to make sure
5835 # the request for the rewritten URL isn't redirected as well)
5836 {+redirect{s@$@&mode=expanded@}}
5837 undeadly.org/cgi\?action=article&sid=\d*$
5839 # Redirect Google search requests to MSN
5840 {+redirect{s@^http://[^/]*/search\?q=([^&]*).*@http://search.msn.com/results.aspx?q=$1@}}
5843 # Redirect MSN search requests to Yahoo
5844 {+redirect{s@^http://[^/]*/results\.aspx\?q=([^&]*).*@http://search.yahoo.com/search?p=$1@}}
5845 search.msn.com//results\.aspx\?q=
5847 # Redirect http://example.com/&bla=fasel&toChange=foo (and any other value but "bar")
5848 # to http://example.com/&bla=fasel&toChange=bar
5850 # The URL pattern makes sure that the following request isn't redirected again.
5851 {+redirect{s@toChange=[^&]+@toChange=bar@}}
5852 example.com/.*toChange=(?!bar)
5854 # Add a shortcut to look up illumos bugs
5855 {+redirect{s@^http://i([0-9]+)/.*@https://www.illumos.org/issues/$1@}}
5856 # Redirected URL = http://i4974/
5857 # Redirect Destination = https://www.illumos.org/issues/4974
5858 i[0-9][0-9][0-9][0-9]*/
5860 # Redirect requests for the old Tor Hidden Service of the Privoxy website to the new one
5861 {+redirect{s@^http://jvauzb4sb3bwlsnc.onion/@http://l3tczdiiwoo63iwxty4lhs6p7eaxop5micbn7vbliydgv63x5zrrrfyd.onion/@}}
5862 jvauzb4sb3bwlsnc.onion/
5864 # Redirect remote requests for this manual
5865 # to the local version delivered by Privoxy
5866 {+redirect{s@^http://www@http://config@}}
5867 www.privoxy.org/user-manual/</screen>
5875 <!-- ~~~~~ New section ~~~~~ -->
5876 <sect3 renderas="sect4" id="server-header-filter">
5877 <title>server-header-filter</title>
5881 <term>Typical use:</term>
5884 Rewrite or remove single server headers.
5890 <term>Effect:</term>
5893 All server headers to which this action applies are filtered on-the-fly
5894 through the specified regular expression based substitutions.
5901 <!-- boolean, parameterized, Multi-value -->
5903 <para>Multi-value.</para>
5908 <term>Parameter:</term>
5911 The name of a server-header filter, as defined in one of the
5912 <link linkend="filter-file">filter files</link>.
5921 Server-header filters are applied to each header on its own, not to
5922 all at once. This makes it easier to diagnose problems, but on the downside
5923 you can't write filters that only change header x if header y's value is z.
5924 You can do that by using tags though.
5927 Server-header filters are executed after the other header actions have finished
5928 and use their output as input.
5931 Please refer to the <link linkend="filter-file">filter file chapter</link>
5932 to learn which server-header filters are available by default, and how to
5939 <term>Example usage (section):</term>
5942 {+server-header-filter{html-to-xml}}
5943 example.org/xml-instance-that-is-delivered-as-html
5945 {+server-header-filter{xml-to-html}}
5946 example.org/instance-that-is-delivered-as-xml-but-is-not
5955 <!-- ~~~~~ New section ~~~~~ -->
5956 <sect3 renderas="sect4" id="server-header-tagger">
5957 <title>server-header-tagger</title>
5961 <term>Typical use:</term>
5964 Enable or disable filters based on the Content-Type header.
5970 <term>Effect:</term>
5973 Server headers to which this action applies are filtered on-the-fly through
5974 the specified regular expression based substitutions, the result is used as
5982 <!-- boolean, parameterized, Multi-value -->
5984 <para>Multi-value.</para>
5989 <term>Parameter:</term>
5992 The name of a server-header tagger, as defined in one of the
5993 <link linkend="filter-file">filter files</link>.
6002 Server-header taggers are applied to each header on its own,
6003 and as the header isn't modified, each tagger <quote>sees</quote>
6007 Server-header taggers are executed before all other header actions
6008 that modify server headers. Their tags can be used to control
6009 all of the other server-header actions, the content filters
6010 and the crunch actions (<link linkend="redirect">redirect</link>
6011 and <link linkend="block">block</link>).
6014 Obviously crunching based on tags created by server-header taggers
6015 doesn't prevent the request from showing up in the server's log file.
6022 <term>Example usage (section):</term>
6025 # Tag every request with the content type declared by the server
6026 {+server-header-tagger{content-type}}
6029 # If the response has a tag starting with 'image/' enable an external
6030 # filter that only applies to images.
6032 # Note that the filter is not available by default, it's just a
6033 # <literal><link linkend="external-filter-syntax">silly example</link></literal>.
6034 {+external-filter{rotate-image} +force-text-mode}
6044 <!-- ~~~~~ New section ~~~~~ -->
6045 <sect3 renderas="sect4" id="suppress-tag">
6046 <title>suppress-tag</title>
6050 <term>Typical use:</term>
6053 Suppress client or server tag.
6059 <term>Effect:</term>
6062 Server or client tags to which this action applies are not added to the request,
6063 thus making all actions that are specific to these request tags inactive.
6070 <!-- boolean, parameterized, Multi-value -->
6072 <para>Multi-value.</para>
6077 <term>Parameter:</term>
6080 The result tag of a server-header or client-header tagger, as defined in one of the
6081 <link linkend="filter-file">filter files</link>.
6087 <term>Example usage (section):</term>
6090 # Suppress tag produced by range-requests client-header tagger for requests coming from address 10.0.0.1
6091 {+suppress-tag{RANGE-REQUEST}}
6092 TAG:^IP-ADDRESS: 10\.0\.0\.1$
6101 <!-- ~~~~~ New section ~~~~~ -->
6102 <sect3 renderas="sect4" id="session-cookies-only">
6103 <title>session-cookies-only</title>
6107 <term>Typical use:</term>
6110 Allow only temporary <quote>session</quote> cookies (for the current
6111 browser session <emphasis>only</emphasis>).
6117 <term>Effect:</term>
6120 Deletes the <quote>expires</quote> field from <quote>Set-Cookie:</quote>
6121 server headers. Most browsers will not store such cookies permanently and
6122 forget them in between sessions.
6129 <!-- Boolean, Parameterized, Multi-value -->
6131 <para>Boolean.</para>
6136 <term>Parameter:</term>
6148 This is less strict than <literal><link linkend="crunch-incoming-cookies">crunch-incoming-cookies</link></literal> /
6149 <literal><link linkend="crunch-outgoing-cookies">crunch-outgoing-cookies</link></literal> and allows you to browse
6150 websites that insist or rely on setting cookies, without compromising your privacy too badly.
6153 Most browsers will not permanently store cookies that have been processed by
6154 <literal>session-cookies-only</literal> and will forget about them between sessions.
6155 This makes profiling cookies useless, but won't break sites which require cookies so
6156 that you can log in for transactions. This is generally turned on for all
6157 sites, and is the recommended setting.
6160 It makes <emphasis>no sense at all</emphasis> to use <literal>session-cookies-only</literal>
6161 together with <literal><link linkend="crunch-incoming-cookies">crunch-incoming-cookies</link></literal> or
6162 <literal><link linkend="crunch-outgoing-cookies">crunch-outgoing-cookies</link></literal>. If you do, cookies
6163 will be plainly killed.
6166 Note that it is up to the browser how it handles such cookies without an <quote>expires</quote>
6167 field. If you use an exotic browser, you might want to try it out to be sure.
6170 This setting also has no effect on cookies that may have been stored
6171 previously by the browser before starting <application>Privoxy</application>.
6172 These would have to be removed manually.
6175 <application>Privoxy</application> also uses
6176 the <link linkend="filter-content-cookies">content-cookies filter</link>
6177 to block some types of cookies. Content cookies are not effected by
6178 <literal>session-cookies-only</literal>.
6184 <term>Example usage:</term>
6186 <screen>+session-cookies-only</screen>
6193 <!-- ~~~~~ New section ~~~~~ -->
6194 <sect3 renderas="sect4" id="set-image-blocker">
6195 <title>set-image-blocker</title>
6199 <term>Typical use:</term>
6201 <para>Choose the replacement for blocked images</para>
6206 <term>Effect:</term>
6209 This action alone doesn't do anything noticeable. If <emphasis>both</emphasis>
6210 <literal><link linkend="block">block</link></literal> <emphasis>and</emphasis> <literal><link
6211 linkend="handle-as-image">handle-as-image</link></literal> <emphasis>also</emphasis>
6212 apply, i.e. if the request is to be blocked as an image,
6213 <emphasis>then</emphasis> the parameter of this action decides what will be
6214 sent as a replacement.
6221 <!-- Boolean, Parameterized, Multi-value -->
6223 <para>Parameterized.</para>
6228 <term>Parameter:</term>
6233 <quote>pattern</quote> to send a built-in checkerboard pattern image. The image is visually
6234 decent, scales very well, and makes it obvious where banners were busted.
6239 <quote>blank</quote> to send a built-in transparent image. This makes banners disappear
6240 completely, but makes it hard to detect where <application>Privoxy</application> has blocked
6241 images on a given page and complicates troubleshooting if <application>Privoxy</application>
6242 has blocked innocent images, like navigation icons.
6247 <quote><replaceable class="parameter">target-url</replaceable></quote> to
6248 send a redirect to <replaceable class="parameter">target-url</replaceable>. You can redirect
6249 to any image anywhere, even in your local filesystem via <quote>file:///</quote> URL.
6250 (But note that not all browsers support redirecting to a local file system).
6253 A good application of redirects is to use special <application>Privoxy</application>-built-in
6254 URLs, which send the built-in images, as <replaceable class="parameter">target-url</replaceable>.
6255 This has the same visual effect as specifying <quote>blank</quote> or <quote>pattern</quote> in
6256 the first place, but enables your browser to cache the replacement image, instead of requesting
6257 it over and over again.
6268 The URLs for the built-in images are <quote>http://config.privoxy.org/send-banner?type=<replaceable
6269 class="parameter">type</replaceable></quote>, where <replaceable class="parameter">type</replaceable> is
6270 either <quote>blank</quote> or <quote>pattern</quote>.
6273 There is a third (advanced) type, called <quote>auto</quote>. It is <emphasis>NOT</emphasis> to be
6274 used in <literal>set-image-blocker</literal>, but meant for use from <link linkend="filter-file">filters</link>.
6275 Auto will select the type of image that would have applied to the referring page, had it been an image.
6281 <term>Example usage:</term>
6286 <screen>+set-image-blocker{pattern}</screen>
6288 Redirect to the BSD daemon:
6290 <screen>+set-image-blocker{http://www.freebsd.org/gifs/dae_up3.gif}</screen>
6292 Redirect to the built-in pattern for better caching:
6294 <screen>+set-image-blocker{http://config.privoxy.org/send-banner?type=pattern}</screen>
6301 <!-- ~~~~~ New section ~~~~~ -->
6302 <sect3 id="summary">
6303 <title>Summary</title>
6305 Note that many of these actions have the potential to cause a page to
6306 misbehave, possibly even not to display at all. There are many ways
6307 a site designer may choose to design his site, and what HTTP header
6308 content, and other criteria, he may depend on. There is no way to have hard
6309 and fast rules for all sites. See the <link
6310 linkend="ACTIONSANAT">Appendix</link> for a brief example on troubleshooting
6316 <!-- ~~~~~ New section ~~~~~ -->
6317 <sect2 id="aliases">
6318 <title>Aliases</title>
6320 Custom <quote>actions</quote>, known to <application>Privoxy</application>
6321 as <quote>aliases</quote>, can be defined by combining other actions.
6322 These can in turn be invoked just like the built-in actions.
6323 Currently, an alias name can contain any character except space, tab,
6325 <quote>{</quote> and <quote>}</quote>, but we <emphasis>strongly
6326 recommend</emphasis> that you only use <quote>a</quote> to <quote>z</quote>,
6327 <quote>0</quote> to <quote>9</quote>, <quote>+</quote>, and <quote>-</quote>.
6328 Alias names are not case sensitive, and are not required to start with a
6329 <quote>+</quote> or <quote>-</quote> sign, since they are merely textually
6333 Aliases can be used throughout the actions file, but they <emphasis>must be
6334 defined in a special section at the top of the file!</emphasis>
6335 And there can only be one such section per actions file. Each actions file may
6336 have its own alias section, and the aliases defined in it are only visible
6340 There are two main reasons to use aliases: One is to save typing for frequently
6341 used combinations of actions, the other one is a gain in flexibility: If you
6342 decide once how you want to handle shops by defining an alias called
6343 <quote>shop</quote>, you can later change your policy on shops in
6344 <emphasis>one</emphasis> place, and your changes will take effect everywhere
6345 in the actions file where the <quote>shop</quote> alias is used. Calling aliases
6346 by their purpose also makes your actions files more readable.
6349 Currently, there is one big drawback to using aliases, though:
6350 <application>Privoxy</application>'s built-in web-based action file
6351 editor honors aliases when reading the actions files, but it expands
6352 them before writing. So the effects of your aliases are of course preserved,
6353 but the aliases themselves are lost when you edit sections that use aliases
6358 Now let's define some aliases...
6362 # Useful custom aliases we can use later.
6364 # Note the (required!) section header line and that this section
6365 # must be at the top of the actions file!
6369 # These aliases just save typing later:
6370 # (Note that some already use other aliases!)
6372 +crunch-all-cookies = +<link linkend="CRUNCH-INCOMING-COOKIES">crunch-incoming-cookies</link> +<link linkend="CRUNCH-OUTGOING-COOKIES">crunch-outgoing-cookies</link>
6373 -crunch-all-cookies = -<link linkend="CRUNCH-INCOMING-COOKIES">crunch-incoming-cookies</link> -<link linkend="CRUNCH-OUTGOING-COOKIES">crunch-outgoing-cookies</link>
6374 +block-as-image = +block{Blocked image.} +handle-as-image
6375 allow-all-cookies = -crunch-all-cookies -<link linkend="SESSION-COOKIES-ONLY">session-cookies-only</link> -<link linkend="FILTER-CONTENT-COOKIES">filter{content-cookies}</link>
6377 # These aliases define combinations of actions
6378 # that are useful for certain types of sites:
6380 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>
6382 shop = -crunch-all-cookies -<link linkend="FILTER-ALL-POPUPS">filter{all-popups}</link>
6384 # Short names for other aliases, for really lazy people ;-)
6386 c0 = +crunch-all-cookies
6387 c1 = -crunch-all-cookies</screen>
6390 ...and put them to use. These sections would appear in the lower part of an
6391 actions file and define exceptions to the default actions (as specified further
6392 up for the <quote>/</quote> pattern):
6396 # These sites are either very complex or very keen on
6397 # user data and require minimal interference to work:
6400 .office.microsoft.com
6401 .windowsupdate.microsoft.com
6402 # Gmail is really mail.google.com, not gmail.com
6406 # Allow cookies (for setting and retrieving your customer data)
6410 .worldpay.com # for quietpc.com
6413 # These shops require pop-ups:
6415 {-filter{all-popups} -filter{unsolicited-popups}}
6417 .overclockers.co.uk</screen>
6420 Aliases like <quote>shop</quote> and <quote>fragile</quote> are typically used for
6421 <quote>problem</quote> sites that require more than one action to be disabled
6422 in order to function properly.
6428 <!-- ~~~~~ New section ~~~~~ -->
6429 <sect2 id="act-examples">
6430 <title>Actions Files Tutorial</title>
6432 The above chapters have shown <link linkend="actions-file">which actions files
6433 there are and how they are organized</link>, how actions are <link
6434 linkend="actions">specified</link> and <link linkend="actions-apply">applied
6435 to URLs</link>, how <link linkend="af-patterns">patterns</link> work, and how to
6436 define and use <link linkend="aliases">aliases</link>. Now, let's look at an
6437 example <filename>match-all.action</filename>, <filename>default.action</filename>
6438 and <filename>user.action</filename> file and see how all these pieces come together:
6441 <sect3 id="match-all">
6442 <title>match-all.action</title>
6444 Remember <emphasis>all actions are disabled when matching starts</emphasis>,
6445 so we have to explicitly enable the ones we want.
6449 While the <filename>match-all.action</filename> file only contains a
6450 single section, it is probably the most important one. It has only one
6451 pattern, <quote><literal>/</literal></quote>, but this pattern
6452 <link linkend="af-patterns">matches all URLs</link>. Therefore, the set of
6453 actions used in this <quote>default</quote> section <emphasis>will
6454 be applied to all requests as a start</emphasis>. It can be partly or
6455 wholly overridden by other actions files like <filename>default.action</filename>
6456 and <filename>user.action</filename>, but it will still be largely responsible
6457 for your overall browsing experience.
6461 Again, at the start of matching, all actions are disabled, so there is
6462 no need to disable any actions here. (Remember: a <quote>+</quote>
6463 preceding the action name enables the action, a <quote>-</quote> disables!).
6464 Also note how this long line has been made more readable by splitting it into
6465 multiple lines with line continuation.
6470 +<link linkend="CHANGE-X-FORWARDED-FOR">change-x-forwarded-for{block}</link> \
6471 +<link linkend="HIDE-FROM-HEADER">hide-from-header{block}</link> \
6472 +<link linkend="SET-IMAGE-BLOCKER">set-image-blocker{pattern}</link> \
6478 The default behavior is now set.
6482 <sect3 id="default-action">
6483 <title>default.action</title>
6486 If you aren't a developer, there's no need for you to edit the
6487 <filename>default.action</filename> file. It is maintained by
6488 the &my-app; developers and if you disagree with some of the
6489 sections, you should overrule them in your <filename>user.action</filename>.
6493 Understanding the <filename>default.action</filename> file can
6494 help you with your <filename>user.action</filename>, though.
6498 The first section in this file is a special section for internal use
6499 that prevents older &my-app; versions from reading the file:
6503 ##########################################################################
6504 # Settings -- Don't change! For internal Privoxy use ONLY.
6505 ##########################################################################
6507 for-privoxy-version=3.0.11</screen>
6510 After that comes the (optional) alias section. We'll use the example
6511 section from the above <link linkend="aliases">chapter on aliases</link>,
6512 that also explains why and how aliases are used:
6516 ##########################################################################
6518 ##########################################################################
6521 # These aliases just save typing later:
6522 # (Note that some already use other aliases!)
6524 +crunch-all-cookies = +<link linkend="CRUNCH-INCOMING-COOKIES">crunch-incoming-cookies</link> +<link linkend="CRUNCH-OUTGOING-COOKIES">crunch-outgoing-cookies</link>
6525 -crunch-all-cookies = -<link linkend="CRUNCH-INCOMING-COOKIES">crunch-incoming-cookies</link> -<link linkend="CRUNCH-OUTGOING-COOKIES">crunch-outgoing-cookies</link>
6526 +block-as-image = +block{Blocked image.} +handle-as-image
6527 mercy-for-cookies = -crunch-all-cookies -<link linkend="SESSION-COOKIES-ONLY">session-cookies-only</link> -<link linkend="FILTER-CONTENT-COOKIES">filter{content-cookies}</link>
6529 # These aliases define combinations of actions
6530 # that are useful for certain types of sites:
6532 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>
6533 shop = -crunch-all-cookies -<link linkend="FILTER-ALL-POPUPS">filter{all-popups}</link></screen>
6536 The first of our specialized sections is concerned with <quote>fragile</quote>
6537 sites, i.e. sites that require minimum interference, because they are either
6538 very complex or very keen on tracking you (and have mechanisms in place that
6539 make them unusable for people who avoid being tracked). We will use
6540 our pre-defined <literal>fragile</literal> alias instead of stating the list
6541 of actions explicitly:
6545 ##########################################################################
6546 # Exceptions for sites that'll break under the default action set:
6547 ##########################################################################
6549 # "Fragile" Use a minimum set of actions for these sites (see alias above):
6552 .office.microsoft.com # surprise, surprise!
6553 .windowsupdate.microsoft.com
6554 mail.google.com</screen>
6557 Shopping sites are not as fragile, but they typically
6558 require cookies to log in, and pop-up windows for shopping
6559 carts or item details. Again, we'll use a pre-defined alias:
6567 .worldpay.com # for quietpc.com
6569 .scan.co.uk</screen>
6572 The <literal><link linkend="FAST-REDIRECTS">fast-redirects</link></literal>
6573 action, which may have been enabled in <filename>match-all.action</filename>,
6574 breaks some sites. So disable it for popular sites where we know it misbehaves:
6578 { -<link linkend="FAST-REDIRECTS">fast-redirects</link> }
6582 .altavista.com/.*(like|url|link):http
6583 .altavista.com/trans.*urltext=http
6584 .nytimes.com</screen>
6587 It is important that <application>Privoxy</application> knows which
6588 URLs belong to images, so that <emphasis>if</emphasis> they are to
6589 be blocked, a substitute image can be sent, rather than an HTML page.
6590 Contacting the remote site to find out is not an option, since it
6591 would destroy the loading time advantage of banner blocking, and it
6592 would feed the advertisers information about you. We can mark any
6593 URL as an image with the <literal><link
6594 linkend="handle-as-image">handle-as-image</link></literal> action,
6595 and marking all URLs that end in a known image file extension is a
6600 ##########################################################################
6602 ##########################################################################
6604 # Define which file types will be treated as images, in case they get
6605 # blocked further down this file:
6607 { +<link linkend="HANDLE-AS-IMAGE">handle-as-image</link> }
6608 /.*\.(gif|jpe?g|png|bmp|ico)$</screen>
6611 And then there are known banner sources. They often use scripts to
6612 generate the banners, so it won't be visible from the URL that the
6613 request is for an image. Hence we block them <emphasis>and</emphasis>
6614 mark them as images in one go, with the help of our
6615 <literal>+block-as-image</literal> alias defined above. (We could of
6616 course just as well use <literal>+<link linkend="block">block</link>
6617 +<link linkend="handle-as-image">handle-as-image</link></literal> here.)
6618 Remember that the type of the replacement image is chosen by the
6619 <literal><link linkend="set-image-blocker">set-image-blocker</link></literal>
6620 action. Since all URLs have matched the default section with its
6621 <literal>+<link linkend="set-image-blocker">set-image-blocker</link>{pattern}</literal>
6622 action before, it still applies and needn't be repeated:
6626 # Known ad generators:
6631 .ad.*.doubleclick.net
6632 .a.yimg.com/(?:(?!/i/).)*$
6633 .a[0-9].yimg.com/(?:(?!/i/).)*$
6638 One of the most important jobs of <application>Privoxy</application>
6639 is to block banners. Many of these can be <quote>blocked</quote>
6640 by the <literal><link linkend="filter">filter</link>{banners-by-size}</literal>
6641 action, which we enabled above, and which deletes the references to banner
6642 images from the pages while they are loaded, so the browser doesn't request
6643 them anymore, and hence they don't need to be blocked here. But this naturally
6644 doesn't catch all banners, and some people choose not to use filters, so we
6645 need a comprehensive list of patterns for banner URLs here, and apply the
6646 <literal><link linkend="block">block</link></literal> action to them.
6649 First comes many generic patterns, which do most of the work, by
6650 matching typical domain and path name components of banners. Then comes
6651 a list of individual patterns for specific sites, which is omitted here
6652 to keep the example short:
6656 ##########################################################################
6657 # Block these fine banners:
6658 ##########################################################################
6659 { <link linkend="BLOCK">+block{Banner ads.}</link> }
6667 /.*count(er)?\.(pl|cgi|exe|dll|asp|php[34]?)
6668 /(?:.*/)?(publicite|werbung|rekla(ma|me|am)|annonse|maino(kset|nta|s)?)/
6670 # Site-specific patterns (abbreviated):
6672 .hitbox.com</screen>
6675 It's quite remarkable how many advertisers actually call their banner
6676 servers ads.<replaceable>company</replaceable>.com, or call the directory
6677 in which the banners are stored literally <quote>banners</quote>. So the above
6678 generic patterns are surprisingly effective.
6681 But being very generic, they necessarily also catch URLs that we don't want
6682 to block. The pattern <literal>.*ads.</literal> e.g. catches
6683 <quote>nasty-<emphasis>ads</emphasis>.nasty-corp.com</quote> as intended,
6684 but also <quote>downlo<emphasis>ads</emphasis>.sourcefroge.net</quote> or
6685 <quote><emphasis>ads</emphasis>l.some-provider.net.</quote> So here come some
6686 well-known exceptions to the <literal>+<link linkend="BLOCK">block</link></literal>
6690 Note that these are exceptions to exceptions from the default! Consider the URL
6691 <quote>downloads.sourcefroge.net</quote>: Initially, all actions are deactivated,
6692 so it wouldn't get blocked. Then comes the defaults section, which matches the
6693 URL, but just deactivates the <literal><link linkend="BLOCK">block</link></literal>
6694 action once again. Then it matches <literal>.*ads.</literal>, an exception to the
6695 general non-blocking policy, and suddenly
6696 <literal><link linkend="BLOCK">+block</link></literal> applies. And now, it'll match
6697 <literal>.*loads.</literal>, where <literal><link linkend="BLOCK">-block</link></literal>
6698 applies, so (unless it matches <emphasis>again</emphasis> further down) it ends up
6699 with no <literal><link linkend="BLOCK">block</link></literal> action applying.
6703 ##########################################################################
6704 # Save some innocent victims of the above generic block patterns:
6705 ##########################################################################
6709 { -<link linkend="BLOCK">block</link> }
6710 adv[io]*. # (for advogato.org and advice.*)
6711 adsl. # (has nothing to do with ads)
6712 adobe. # (has nothing to do with ads either)
6713 ad[ud]*. # (adult.* and add.*)
6714 .edu # (universities don't host banners (yet!))
6715 .*loads. # (downloads, uploads etc)
6723 www.globalintersec.com/adv # (adv = advanced)
6724 www.ugu.com/sui/ugu/adv</screen>
6727 Filtering source code can have nasty side effects,
6728 so make an exception for our friends at sourceforge.net,
6729 and all paths with <quote>cvs</quote> in them. Note that
6730 <literal>-<link linkend="FILTER">filter</link></literal>
6731 disables <emphasis>all</emphasis> filters in one fell swoop!
6735 # Don't filter code!
6737 { -<link linkend="FILTER">filter</link> }
6742 .sourceforge.net</screen>
6745 The actual <filename>default.action</filename> is of course much more
6746 comprehensive, but we hope this example made clear how it works.
6751 <sect3 id="user-action"><title>user.action</title>
6754 So far we are painting with a broad brush by setting general policies,
6755 which would be a reasonable starting point for many people. Now,
6756 you might want to be more specific and have customized rules that
6757 are more suitable to your personal habits and preferences. These would
6758 be for narrowly defined situations like your ISP or your bank, and should
6759 be placed in <filename>user.action</filename>, which is parsed after all other
6760 actions files and hence has the last word, over-riding any previously
6761 defined actions. <filename>user.action</filename> is also a
6762 <emphasis>safe</emphasis> place for your personal settings, since
6763 <filename>default.action</filename> is actively maintained by the
6764 <application>Privoxy</application> developers and you'll probably want
6765 to install updated versions from time to time.
6769 So let's look at a few examples of things that one might typically do in
6770 <filename>user.action</filename>:
6774 <!-- brief sample user.action here -->
6777 # My user.action file. <fred@example.com></screen>
6780 As <link linkend="aliases">aliases</link> are local to the actions
6781 file that they are defined in, you can't use the ones from
6782 <filename>default.action</filename>, unless you repeat them here:
6786 # Aliases are local to the file they are defined in.
6787 # (Re-)define aliases for this file:
6791 # These aliases just save typing later, and the alias names should
6792 # be self explanatory.
6794 +crunch-all-cookies = +crunch-incoming-cookies +crunch-outgoing-cookies
6795 -crunch-all-cookies = -crunch-incoming-cookies -crunch-outgoing-cookies
6796 allow-all-cookies = -crunch-all-cookies -session-cookies-only
6797 allow-popups = -filter{all-popups}
6798 +block-as-image = +block{Blocked as image.} +handle-as-image
6799 -block-as-image = -block
6801 # These aliases define combinations of actions that are useful for
6802 # certain types of sites:
6804 fragile = -block -crunch-all-cookies -filter -fast-redirects -hide-referrer
6805 shop = -crunch-all-cookies allow-popups
6807 # Allow ads for selected useful free sites:
6809 allow-ads = -block -filter{banners-by-size} -filter{banners-by-link}
6811 # Alias for specific file types that are text, but might have conflicting
6812 # MIME types. We want the browser to force these to be text documents.
6813 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>
6816 Say you have accounts on some sites that you visit regularly, and
6817 you don't want to have to log in manually each time. So you'd like
6818 to allow persistent cookies for these sites. The
6819 <literal>allow-all-cookies</literal> alias defined above does exactly
6820 that, i.e. it disables crunching of cookies in any direction, and the
6821 processing of cookies to make them only temporary.
6825 { allow-all-cookies }
6829 .redhat.com</screen>
6832 Your bank is allergic to some filter, but you don't know which, so you disable them all:
6836 { -<link linkend="FILTER">filter</link> }
6837 .your-home-banking-site.com</screen>
6840 Some file types you may not want to filter for various reasons:
6844 # Technical documentation is likely to contain strings that might
6845 # erroneously get altered by the JavaScript-oriented filters:
6850 # And this stupid host sends streaming video with a wrong MIME type,
6851 # so that Privoxy thinks it is getting HTML and starts filtering:
6853 stupid-server.example.com/</screen>
6856 Example of a simple <link linkend="BLOCK">block</link> action. Say you've
6857 seen an ad on your favourite page on example.com that you want to get rid of.
6858 You have right-clicked the image, selected <quote>copy image location</quote>
6859 and pasted the URL below while removing the leading http://, into a
6860 <literal>{ +block{} }</literal> section. Note that <literal>{ +handle-as-image
6861 }</literal> need not be specified, since all URLs ending in
6862 <literal>.gif</literal> will be tagged as images by the general rules as set
6863 in default.action anyway:
6867 { +<link linkend="BLOCK">block</link>{Nasty ads.} }
6868 www.example.com/nasty-ads/sponsor\.gif
6869 another.example.net/more/junk/here/</screen>
6872 The URLs of dynamically generated banners, especially from large banner
6873 farms, often don't use the well-known image file name extensions, which
6874 makes it impossible for <application>Privoxy</application> to guess
6875 the file type just by looking at the URL.
6876 You can use the <literal>+block-as-image</literal> alias defined above for
6878 Note that objects which match this rule but then turn out NOT to be an
6879 image are typically rendered as a <quote>broken image</quote> icon by the
6880 browser. Use cautiously.
6888 ar.atwola.com/</screen>
6891 Now you noticed that the default configuration breaks Forbes Magazine,
6892 but you were too lazy to find out which action is the culprit, and you
6893 were again too lazy to give <link linkend="contact">feedback</link>, so
6894 you just used the <literal>fragile</literal> alias on the site, and
6895 -- <emphasis>whoa!</emphasis> -- it worked. The <literal>fragile</literal>
6896 aliases disables those actions that are most likely to break a site. Also,
6897 good for testing purposes to see if it is <application>Privoxy</application>
6898 that is causing the problem or not. We later find other regular sites
6899 that misbehave, and add those to our personalized list of troublemakers:
6906 .mybank.com</screen>
6909 You like the <quote>fun</quote> text replacements in <filename>default.filter</filename>,
6910 but it is disabled in the distributed actions file.
6911 So you'd like to turn it on in your private,
6912 update-safe config, once and for all:
6916 { +<link linkend="filter-fun">filter{fun}</link> }
6917 / # For ALL sites!</screen>
6920 Note that the above is not really a good idea: There are exceptions
6921 to the filters in <filename>default.action</filename> for things that
6922 really shouldn't be filtered, like code on CVS->Web interfaces. Since
6923 <filename>user.action</filename> has the last word, these exceptions
6924 won't be valid for the <quote>fun</quote> filtering specified here.
6928 You might also worry about how your favourite free websites are
6929 funded, and find that they rely on displaying banner advertisements
6930 to survive. So you might want to specifically allow banners for those
6931 sites that you feel provide value to you:
6941 Note that <literal>allow-ads</literal> has been aliased to
6942 <literal>-<link linkend="block">block</link></literal>,
6943 <literal>-<link linkend="filter-banners-by-size">filter{banners-by-size}</link></literal>, and
6944 <literal>-<link linkend="filter-banners-by-link">filter{banners-by-link}</link></literal> above.
6948 Invoke another alias here to force an over-ride of the MIME type <literal>
6949 application/x-sh</literal> which typically would open a download type
6950 dialog. In my case, I want to look at the shell script, and then I can save
6951 it should I choose to.
6959 <filename>user.action</filename> is generally the best place to define
6960 exceptions and additions to the default policies of
6961 <filename>default.action</filename>. Some actions are safe to have their
6962 default policies set here though. So let's set a default policy to have a
6963 <quote>blank</quote> image as opposed to the checkerboard pattern for
6964 <emphasis>ALL</emphasis> sites. <quote>/</quote> of course matches all URL
6969 { +<link linkend="set-image-blocker">set-image-blocker{blank}</link> }
6970 / # ALL sites</screen>
6975 <!-- ~ End section ~ -->
6979 <!-- ~ End section ~ -->
6981 <!-- ~~~~~~~~ New section Header ~~~~~~~~~ -->
6983 <sect1 id="filter-file">
6984 <title>Filter Files</title>
6987 On-the-fly text substitutions need
6988 to be defined in a <quote>filter file</quote>. Once defined, they
6989 can then be invoked as an <quote>action</quote>.
6993 &my-app; supports four different pcrs-based filter actions:
6994 <literal><link linkend="filter">filter</link></literal> to
6995 rewrite the content that is send to the client,
6996 <literal><link linkend="client-header-filter">client-header-filter</link></literal>
6997 to rewrite headers that are send by the client,
6998 <literal><link linkend="server-header-filter">server-header-filter</link></literal>
6999 to rewrite headers that are send by the server, and
7000 <literal><link linkend="client-body-filter">client-body-filter</link></literal>
7001 to rewrite client request body.
7005 &my-app; also supports two tagger actions:
7006 <literal><link linkend="client-header-tagger">client-header-tagger</link></literal>
7008 <literal><link linkend="server-header-tagger">server-header-tagger</link></literal>.
7009 Taggers and filters use the same syntax in the filter files, the difference
7010 is that taggers don't modify the text they are filtering, but use a rewritten
7011 version of the filtered text as tag. The tags can then be used to change the
7012 applying actions through sections with <link linkend="tag-pattern">tag-patterns</link>.
7016 Finally &my-app; supports the
7017 <literal><link linkend="external-filter">external-filter</link></literal> action
7018 to enable <literal><link linkend="external-filter-syntax">external filters</link></literal>
7019 written in proper programming languages.
7024 Multiple filter files can be defined through the <literal> <link
7025 linkend="filterfile">filterfile</link></literal> config directive. The filters
7026 as supplied by the developers are located in
7027 <filename>default.filter</filename>. It is recommended that any locally
7028 defined or modified filters go in a separately defined file such as
7029 <filename>user.filter</filename>.
7033 Common tasks for content filters are to eliminate common annoyances in
7034 HTML and JavaScript, such as pop-up windows,
7035 exit consoles, crippled windows without navigation tools, the
7036 infamous <BLINK> tag etc, to suppress images with certain
7037 width and height attributes (standard banner sizes or web-bugs),
7038 or just to have fun.
7042 Enabled content filters are applied to any content whose
7043 <quote>Content Type</quote> header is recognised as a sign
7044 of text-based content, with the exception of <literal>text/plain</literal>.
7045 Use the <link linkend="FORCE-TEXT-MODE">force-text-mode</link> action
7046 to also filter other content.
7050 Substitutions are made at the source level, so if you want to <quote>roll
7051 your own</quote> filters, you should first be familiar with HTML syntax,
7052 and, of course, regular expressions.
7056 Just like the <link linkend="actions-file">actions files</link>, the
7057 filter file is organized in sections, which are called <emphasis>filters</emphasis>
7058 here. Each filter consists of a heading line, that starts with one of the
7059 <emphasis>keywords</emphasis> <literal>FILTER:</literal>,
7060 <literal>CLIENT-HEADER-FILTER:</literal>, <literal>SERVER-HEADER-FILTER:</literal> or
7061 <literal>CLIENT-BODY-FILTER:</literal>
7062 followed by the filter's <emphasis>name</emphasis>, and a short (one line)
7063 <emphasis>description</emphasis> of what it does. Below that line
7064 come the <emphasis>jobs</emphasis>, i.e. lines that define the actual
7065 text substitutions. By convention, the name of a filter
7066 should describe what the filter <emphasis>eliminates</emphasis>. The
7067 comment is used in the <ulink url="http://config.privoxy.org/">web-based
7068 user interface</ulink>.
7072 Once a filter called <replaceable>name</replaceable> has been defined
7073 in the filter file, it can be invoked by using an action of the form
7074 +<literal><link linkend="filter">filter</link>{<replaceable>name</replaceable>}</literal>
7075 in any <link linkend="actions-file">actions file</link>.
7079 Filter definitions start with a header line that contains the filter
7080 type, the filter name and the filter description.
7081 A content filter header line for a filter called <quote>foo</quote> could look
7085 <screen>FILTER: foo Replace all "foo" with "bar"</screen>
7088 Below that line, and up to the next header line, come the jobs that
7089 define what text replacements the filter executes. They are specified
7090 in a syntax that imitates <ulink url="http://www.perl.org/">Perl</ulink>'s
7091 <literal>s///</literal> operator. If you are familiar with Perl, you
7092 will find this to be quite intuitive, and may want to look at the
7093 PCRS documentation for the subtle differences to Perl behaviour.
7097 Most notably, the non-standard option letter <literal>U</literal> is supported,
7098 which turns the default to ungreedy matching (add <literal>?</literal> to
7099 quantifiers to turn them greedy again).
7103 The non-standard option letter <literal>D</literal> (dynamic) allows
7104 to use the variables $host, $origin (the IP address the request came from),
7105 $path, $url and $listen-address (the address on which Privoxy accepted the
7106 client request. Example: 127.0.0.1:8118).
7107 They will be replaced with the value they refer to before the filter
7112 Note that '$' is a bad choice for a delimiter in a dynamic filter as you
7113 might end up with unintended variables if you use a variable name
7114 directly after the delimiter. Variables will be resolved without
7115 escaping anything, therefore you also have to be careful not to chose
7116 delimiters that appear in the replacement text. For example '<' should
7117 be save, while '?' will sooner or later cause conflicts with $url.
7121 The non-standard option letter <literal>T</literal> (trivial) prevents
7122 parsing for backreferences in the substitute. Use it if you want to include
7123 text like '$&' in your substitute without quoting.
7128 <ulink url="https://en.wikipedia.org/wiki/Regular_expressions"><quote>Regular
7129 Expressions</quote></ulink>, you might want to take a look at
7130 the <link linkend="regex">Appendix on regular expressions</link>, and
7131 see the <ulink url="http://perldoc.perl.org/perlre.html">Perl
7133 <ulink url="http://perldoc.perl.org/perlop.html">the
7134 <literal>s///</literal> operator's syntax</ulink> and <ulink
7135 url="http://perldoc.perl.org/perlre.html">Perl-style regular
7136 expressions</ulink> in general.
7137 The below examples might also help to get you started.
7141 <!-- ~~~~~~~~ New section Header ~~~~~~~~~ -->
7143 <sect2 id="filter-file-tut"><title>Filter File Tutorial</title>
7145 Now, let's complete our <quote>foo</quote> content filter. We have already defined
7146 the heading, but the jobs are still missing. Since all it does is to replace
7147 <quote>foo</quote> with <quote>bar</quote>, there is only one (trivial) job
7151 <screen>s/foo/bar/</screen>
7154 But wait! Didn't the comment say that <emphasis>all</emphasis> occurrences
7155 of <quote>foo</quote> should be replaced? Our current job will only take
7156 care of the first <quote>foo</quote> on each page. For global substitution,
7157 we'll need to add the <literal>g</literal> option:
7160 <screen>s/foo/bar/g</screen>
7163 Our complete filter now looks like this:
7166 <screen>FILTER: foo Replace all "foo" with "bar"
7167 s/foo/bar/g</screen>
7170 Let's look at some real filters for more interesting examples. Here you see
7171 a filter that protects against some common annoyances that arise from JavaScript
7172 abuse. Let's look at its jobs one after the other:
7177 FILTER: js-annoyances Get rid of particularly annoying JavaScript abuse
7179 # Get rid of JavaScript referrer tracking. Test page: http://www.randomoddness.com/untitled.htm
7181 s|(<script.*)document\.referrer(.*</script>)|$1"Not Your Business!"$2|Usg</screen>
7184 Following the header line and a comment, you see the job. Note that it uses
7185 <literal>|</literal> as the delimiter instead of <literal>/</literal>, because
7186 the pattern contains a forward slash, which would otherwise have to be escaped
7187 by a backslash (<literal>\</literal>).
7191 Now, let's examine the pattern: it starts with the text <literal><script.*</literal>
7192 enclosed in parentheses. Since the dot matches any character, and <literal>*</literal>
7193 means: <quote>Match an arbitrary number of the element left of myself</quote>, this
7194 matches <quote><script</quote>, followed by <emphasis>any</emphasis> text, i.e.
7195 it matches the whole page, from the start of the first <script> tag.
7199 That's more than we want, but the pattern continues: <literal>document\.referrer</literal>
7200 matches only the exact string <quote>document.referrer</quote>. The dot needed to
7201 be <emphasis>escaped</emphasis>, i.e. preceded by a backslash, to take away its
7202 special meaning as a joker, and make it just a regular dot. So far, the meaning is:
7203 Match from the start of the first <script> tag in a the page, up to, and including,
7204 the text <quote>document.referrer</quote>, if <emphasis>both</emphasis> are present
7205 in the page (and appear in that order).
7209 But there's still more pattern to go. The next element, again enclosed in parentheses,
7210 is <literal>.*</script></literal>. You already know what <literal>.*</literal>
7211 means, so the whole pattern translates to: Match from the start of the first <script>
7212 tag in a page to the end of the last <script> tag, provided that the text
7213 <quote>document.referrer</quote> appears somewhere in between.
7217 This is still not the whole story, since we have ignored the options and the parentheses:
7218 The portions of the page matched by sub-patterns that are enclosed in parentheses, will be
7219 remembered and be available through the variables <literal>$1, $2, ...</literal> in
7220 the substitute. The <literal>U</literal> option switches to ungreedy matching, which means
7221 that the first <literal>.*</literal> in the pattern will only <quote>eat up</quote> all
7222 text in between <quote><script</quote> and the <emphasis>first</emphasis> occurrence
7223 of <quote>document.referrer</quote>, and that the second <literal>.*</literal> will
7224 only span the text up to the <emphasis>first</emphasis> <quote></script></quote>
7225 tag. Furthermore, the <literal>s</literal> option says that the match may span
7226 multiple lines in the page, and the <literal>g</literal> option again means that the
7227 substitution is global.
7231 So, to summarize, the pattern means: Match all scripts that contain the text
7232 <quote>document.referrer</quote>. Remember the parts of the script from
7233 (and including) the start tag up to (and excluding) the string
7234 <quote>document.referrer</quote> as <literal>$1</literal>, and the part following
7235 that string, up to and including the closing tag, as <literal>$2</literal>.
7239 Now the pattern is deciphered, but wasn't this about substituting things? So
7240 lets look at the substitute: <literal>$1"Not Your Business!"$2</literal> is
7241 easy to read: The text remembered as <literal>$1</literal>, followed by
7242 <literal>"Not Your Business!"</literal> (<emphasis>including</emphasis>
7243 the quotation marks!), followed by the text remembered as <literal>$2</literal>.
7244 This produces an exact copy of the original string, with the middle part
7245 (the <quote>document.referrer</quote>) replaced by <literal>"Not Your
7246 Business!"</literal>.
7250 The whole job now reads: Replace <quote>document.referrer</quote> by
7251 <literal>"Not Your Business!"</literal> wherever it appears inside a
7252 <script> tag. Note that this job won't break JavaScript syntax,
7253 since both the original and the replacement are syntactically valid
7254 string objects. The script just won't have access to the referrer
7255 information anymore.
7259 We'll show you two other jobs from the JavaScript taming department, but
7260 this time only point out the constructs of special interest:
7264 # The status bar is for displaying link targets, not pointless blahblah
7266 s/window\.status\s*=\s*(['"]).*?\1/dUmMy=1/ig</screen>
7269 <literal>\s</literal> stands for whitespace characters (space, tab, newline,
7270 carriage return, form feed), so that <literal>\s*</literal> means: <quote>zero
7271 or more whitespace</quote>. The <literal>?</literal> in <literal>.*?</literal>
7272 makes this matching of arbitrary text ungreedy. (Note that the <literal>U</literal>
7273 option is not set). The <literal>['"]</literal> construct means: <quote>a single
7274 <emphasis>or</emphasis> a double quote</quote>. Finally, <literal>\1</literal> is
7275 a back-reference to the first parenthesis just like <literal>$1</literal> above,
7276 with the difference that in the <emphasis>pattern</emphasis>, a backslash indicates
7277 a back-reference, whereas in the <emphasis>substitute</emphasis>, it's the dollar.
7281 So what does this job do? It replaces assignments of single- or double-quoted
7282 strings to the <quote>window.status</quote> object with a dummy assignment
7283 (using a variable name that is hopefully odd enough not to conflict with
7284 real variables in scripts). Thus, it catches many cases where e.g. pointless
7285 descriptions are displayed in the status bar instead of the link target when
7286 you move your mouse over links.
7290 # Kill OnUnload popups. Yummy. Test: http://www.zdnet.com/zdsubs/yahoo/tree/yfs.html
7292 s/(<body [^>]*)onunload(.*>)/$1never$2/iU</screen>
7296 <ulink url="http://www.w3.org/TR/2000/REC-DOM-Level-2-Events-20001113/events.html#Events-eventgroupings-htmlevents">OnUnload
7297 event binding</ulink> in the HTML DOM was a <emphasis>CRIME</emphasis>.
7298 When I close a browser window, I want it to close and die. Basta.
7299 This job replaces the <quote>onunload</quote> attribute in
7300 <quote><body></quote> tags with the dummy word <literal>never</literal>.
7301 Note that the <literal>i</literal> option makes the pattern matching
7302 case-insensitive. Also note that ungreedy matching alone doesn't always guarantee
7303 a minimal match: In the first parenthesis, we had to use <literal>[^>]*</literal>
7304 instead of <literal>.*</literal> to prevent the match from exceeding the
7305 <body> tag if it doesn't contain <quote>OnUnload</quote>, but the page's
7310 The last example is from the fun department:
7314 FILTER: fun Fun text replacements
7316 # Spice the daily news:
7318 s/microsoft(?!\.com)/MicroSuck/ig</screen>
7321 Note the <literal>(?!\.com)</literal> part (a so-called negative lookahead)
7322 in the job's pattern, which means: Don't match, if the string
7323 <quote>.com</quote> appears directly following <quote>microsoft</quote>
7324 in the page. This prevents links to microsoft.com from being trashed, while
7325 still replacing the word everywhere else.
7329 # Buzzword Bingo (example for extended regex syntax)
7331 s* industry[ -]leading \
7333 | customer[ -]focused \
7334 | market[ -]driven \
7335 | award[ -]winning # Comments are OK, too! \
7336 | high[ -]performance \
7337 | solutions[ -]based \
7341 *<font color="red"><b>BINGO!</b></font> \
7345 The <literal>x</literal> option in this job turns on extended syntax, and allows for
7346 e.g. the liberal use of (non-interpreted!) whitespace for nicer formatting.
7354 <!-- ~~~~~~~~ New section Header ~~~~~~~~~ -->
7356 <sect2 id="predefined-filters"><title>The Pre-defined Filters</title>
7360 Note each filter is also listed in the +filter action section above. Please
7361 keep these listings in sync.
7366 The distribution <filename>default.filter</filename> file contains a selection of
7367 pre-defined filters for your convenience:
7372 <term><emphasis>js-annoyances</emphasis></term>
7375 The purpose of this filter is to get rid of particularly annoying JavaScript abuse.
7381 replaces JavaScript references to the browser's referrer information
7382 with the string "Not Your Business!". This compliments the <literal><link
7383 linkend="hide-referrer">hide-referrer</link></literal> action on the content level.
7388 removes the bindings to the DOM's
7389 <ulink url="http://www.w3.org/TR/2000/REC-DOM-Level-2-Events-20001113/events.html#Events-eventgroupings-htmlevents">unload
7390 event</ulink> which we feel has no right to exist and is responsible for most <quote>exit consoles</quote>, i.e.
7391 nasty windows that pop up when you close another one.
7396 removes code that causes new windows to be opened with undesired properties, such as being
7397 full-screen, non-resizeable, without location, status or menu bar etc.
7402 Use with caution. This is an aggressive filter, and can break sites that
7403 rely heavily on JavaScript.
7409 <term><emphasis>js-events</emphasis></term>
7412 This is a very radical measure. It removes virtually all JavaScript event bindings, which
7413 means that scripts can not react to user actions such as mouse movements or clicks, window
7414 resizing etc, anymore. Use with caution!
7417 We <emphasis>strongly discourage</emphasis> using this filter as a default since it breaks
7418 many legitimate scripts. It is meant for use only on extra-nasty sites (should you really
7425 <term><emphasis>html-annoyances</emphasis></term>
7428 This filter will undo many common instances of HTML based abuse.
7431 The <literal>BLINK</literal> and <literal>MARQUEE</literal> tags
7432 are neutralized (yeah baby!), and browser windows will be created as
7433 resizeable (as of course they should be!), and will have location,
7434 scroll and menu bars -- even if specified otherwise.
7440 <term><emphasis>content-cookies</emphasis></term>
7443 Most cookies are set in the HTTP dialog, where they can be intercepted
7445 <literal><link linkend="crunch-incoming-cookies">crunch-incoming-cookies</link></literal>
7446 and <literal><link linkend="crunch-outgoing-cookies">crunch-outgoing-cookies</link></literal>
7447 actions. But web sites increasingly make use of HTML meta tags and JavaScript
7448 to sneak cookies to the browser on the content level.
7451 This filter disables most HTML and JavaScript code that reads or sets
7452 cookies. It cannot detect all clever uses of these types of code, so it
7453 should not be relied on as an absolute fix. Use it wherever you would also
7454 use the cookie crunch actions.
7460 <term><emphasis>refresh-tags</emphasis></term>
7463 Disable any refresh tags if the interval is greater than nine seconds (so
7464 that redirections done via refresh tags are not destroyed). This is useful
7465 for dial-on-demand setups, or for those who find this HTML feature
7472 <term><emphasis>unsolicited-popups</emphasis></term>
7475 This filter attempts to prevent only <quote>unsolicited</quote> pop-up
7476 windows from opening, yet still allow pop-up windows that the user
7477 has explicitly chosen to open. It was added in version 3.0.1,
7478 as an improvement over earlier such filters.
7481 Technical note: The filter works by redefining the window.open JavaScript
7482 function to a dummy function, <literal>PrivoxyWindowOpen()</literal>,
7483 during the loading and rendering phase of each HTML page access, and
7484 restoring the function afterward.
7487 This is recommended only for browsers that cannot perform this function
7488 reliably themselves. And be aware that some sites require such windows
7489 in order to function normally. Use with caution.
7495 <term><emphasis>all-popups</emphasis></term>
7498 Attempt to prevent <emphasis>all</emphasis> pop-up windows from opening.
7499 Note this should be used with even more discretion than the above, since
7500 it is more likely to break some sites that require pop-ups for normal
7501 usage. Use with caution.
7507 <term><emphasis>img-reorder</emphasis></term>
7510 This is a helper filter that has no value if used alone. It makes the
7511 <literal>banners-by-size</literal> and <literal>banners-by-link</literal>
7512 (see below) filters more effective and should be enabled together with them.
7518 <term><emphasis>banners-by-size</emphasis></term>
7521 This filter removes image tags purely based on what size they are. Fortunately
7522 for us, many ads and banner images tend to conform to certain standardized
7523 sizes, which makes this filter quite effective for ad stripping purposes.
7526 Occasionally this filter will cause false positives on images that are not ads,
7527 but just happen to be of one of the standard banner sizes.
7530 Recommended only for those who require extreme ad blocking. The default
7531 block rules should catch 95+% of all ads <emphasis>without</emphasis> this filter enabled.
7537 <term><emphasis>banners-by-link</emphasis></term>
7540 This is an experimental filter that attempts to kill any banners if
7541 their URLs seem to point to known or suspected click trackers. It is currently
7542 not of much value and is not recommended for use by default.
7548 <term><emphasis>webbugs</emphasis></term>
7551 Webbugs are small, invisible images (technically 1X1 GIF images), that
7552 are used to track users across websites, and collect information on them.
7553 As an HTML page is loaded by the browser, an embedded image tag causes the
7554 browser to contact a third-party site, disclosing the tracking information
7555 through the requested URL and/or cookies for that third-party domain, without
7556 the user ever becoming aware of the interaction with the third-party site.
7557 HTML-ized spam also uses a similar technique to verify email addresses.
7560 This filter removes the HTML code that loads such <quote>webbugs</quote>.
7566 <term><emphasis>tiny-textforms</emphasis></term>
7569 A rather special-purpose filter that can be used to enlarge textareas (those
7570 multi-line text boxes in web forms) and turn off hard word wrap in them.
7571 It was written for the sourceforge.net tracker system where such boxes are
7572 a nuisance, but it can be handy on other sites, too.
7575 It is not recommended to use this filter as a default.
7581 <term><emphasis>jumping-windows</emphasis></term>
7584 Many consider windows that move, or resize themselves to be abusive. This filter
7585 neutralizes the related JavaScript code. Note that some sites might not display
7586 or behave as intended when using this filter. Use with caution.
7592 <term><emphasis>frameset-borders</emphasis></term>
7595 Some web designers seem to assume that everyone in the world will view their
7596 web sites using the same browser brand and version, screen resolution etc,
7597 because only that assumption could explain why they'd use static frame sizes,
7598 yet prevent their frames from being resized by the user, should they be too
7599 small to show their whole content.
7602 This filter removes the related HTML code. It should only be applied to sites
7609 <term><emphasis>demoronizer</emphasis></term>
7612 Many Microsoft products that generate HTML use non-standard extensions (read:
7613 violations) of the ISO 8859-1 aka Latin-1 character set. This can cause those
7614 HTML documents to display with errors on standard-compliant platforms.
7617 This filter translates the MS-only characters into Latin-1 equivalents.
7618 It is not necessary when using MS products, and will cause corruption of
7619 all documents that use 8-bit character sets other than Latin-1. It's mostly
7620 worthwhile for Europeans on non-MS platforms, if weird garbage characters
7621 sometimes appear on some pages, or user agents that don't correct for this on
7624 My version of Mozilla (ancient) shows little square boxes for quote
7625 characters, and apostrophes on moronized pages. So many pages have this, I
7626 can read them fine now. HB 08/27/06
7633 <term><emphasis>shockwave-flash</emphasis></term>
7636 A filter for shockwave haters. As the name suggests, this filter strips code
7637 out of web pages that is used to embed shockwave flash objects.
7645 <term><emphasis>quicktime-kioskmode</emphasis></term>
7648 Change HTML code that embeds Quicktime objects so that kioskmode, which
7649 prevents saving, is disabled.
7655 <term><emphasis>fun</emphasis></term>
7658 Text replacements for subversive browsing fun. Make fun of your favorite
7659 Monopolist or play buzzword bingo.
7665 <term><emphasis>crude-parental</emphasis></term>
7668 A demonstration-only filter that shows how <application>Privoxy</application>
7669 can be used to delete web content on a keyword basis.
7675 <term><emphasis>ie-exploits</emphasis></term>
7678 An experimental collection of text replacements to disable malicious HTML and JavaScript
7679 code that exploits known security holes in Internet Explorer.
7682 Presently, it only protects against Nimda and a cross-site scripting bug, and
7683 would need active maintenance to provide more substantial protection.
7689 <term><emphasis>site-specifics</emphasis></term>
7692 Some web sites have very specific problems, the cure for which doesn't apply
7693 anywhere else, or could even cause damage on other sites.
7696 This is a collection of such site-specific cures which should only be applied
7697 to the sites they were intended for, which is what the supplied
7698 <filename>default.action</filename> file does. Users shouldn't need to change
7699 anything regarding this filter.
7705 <term><emphasis>google</emphasis></term>
7708 A CSS based block for Google text ads. Also removes a width limitation
7709 and the toolbar advertisement.
7715 <term><emphasis>yahoo</emphasis></term>
7718 Another CSS based block, this time for Yahoo text ads. And removes
7719 a width limitation as well.
7725 <term><emphasis>msn</emphasis></term>
7728 Another CSS based block, this time for MSN text ads. And removes
7729 tracking URLs, as well as a width limitation.
7735 <term><emphasis>blogspot</emphasis></term>
7738 Cleans up some Blogspot blogs. Read the fine print before using this one!
7741 This filter also intentionally removes some navigation stuff and sets the
7742 page width to 100%. As a result, some rounded <quote>corners</quote> would
7743 appear to early or not at all and as fixing this would require a browser
7744 that understands background-size (CSS3), they are removed instead.
7750 <term><emphasis>xml-to-html</emphasis></term>
7753 Server-header filter to change the Content-Type from xml to html.
7759 <term><emphasis>html-to-xml</emphasis></term>
7762 Server-header filter to change the Content-Type from html to xml.
7768 <term><emphasis>no-ping</emphasis></term>
7771 Removes the non-standard <literal>ping</literal> attribute from
7772 anchor and area HTML tags.
7778 <term><emphasis>hide-tor-exit-notation</emphasis></term>
7781 Client-header filter to remove the <command>Tor</command> exit node notation
7782 found in Host and Referer headers.
7785 If &my-app; and <command>Tor</command> are chained and &my-app;
7786 is configured to use socks4a, one can use <quote>http://www.example.org.foobar.exit/</quote>
7787 to access the host <quote>www.example.org</quote> through the
7788 <command>Tor</command> exit node <quote>foobar</quote>.
7791 As the HTTP client isn't aware of this notation, it treats the
7792 whole string <quote>www.example.org.foobar.exit</quote> as host and uses it
7793 for the <quote>Host</quote> and <quote>Referer</quote> headers. From the
7794 server's point of view the resulting headers are invalid and can cause problems.
7797 An invalid <quote>Referer</quote> header can trigger <quote>hot-linking</quote>
7798 protections, an invalid <quote>Host</quote> header will make it impossible for
7799 the server to find the right vhost (several domains hosted on the same IP address).
7802 This client-header filter removes the <quote>foo.exit</quote> part in those headers
7803 to prevent the mentioned problems. Note that it only modifies
7804 the HTTP headers, it doesn't make it impossible for the server
7805 to detect your <command>Tor</command> exit node based on the IP address
7806 the request is coming from.
7813 <term><emphasis> </emphasis></term>
7826 <!-- ~~~~~~~~ New section Header ~~~~~~~~~ -->
7827 <sect2 id="external-filter-syntax"><title>External filter syntax</title>
7829 External filters are scripts or programs that can modify the content in
7830 case common <literal><link linkend="filter">filters</link></literal>
7831 aren't powerful enough.
7834 External filters can be written in any language the platform &my-app; runs
7838 They are controlled with the
7839 <literal><link linkend="external-filter">external-filter</link></literal> action
7840 and have to be defined in the <literal><link linkend="filterfile">filterfile</link></literal>
7844 The header looks like any other filter, but instead of pcrs jobs, external
7845 filters contain a single job which can be a program or a shell script (which
7846 may call other scripts or programs).
7849 External filters read the content from STDIN and write the rewritten
7851 The environment variables PRIVOXY_URL, PRIVOXY_PATH, PRIVOXY_HOST,
7852 PRIVOXY_ORIGIN, PRIVOXY_LISTEN_ADDRESS can be used to get some details
7853 about the client request.
7856 &my-app; will temporary store the content to filter in the
7857 <literal><link linkend="temporary-directory">temporary-directory</link></literal>.
7861 EXTERNAL-FILTER: cat Pointless example filter that doesn't actually modify the content
7864 # Incorrect reimplementation of the filter above in POSIX shell.
7866 # Note that it's a single job that spans multiple lines, the line
7867 # breaks are not passed to the shell, thus the semicolons are required.
7869 # If the script isn't trivial, it is recommended to put it into an external file.
7871 # In general, writing external filters entirely in POSIX shell is not
7872 # considered a good idea.
7873 EXTERNAL-FILTER: cat2 Pointless example filter that despite its name may actually modify the content
7879 EXTERNAL-FILTER: rotate-image Rotate an image by 180 degree. Test filter with limited value.
7880 /usr/local/bin/convert - -rotate 180 -
7882 EXTERNAL-FILTER: citation-needed Adds a "[citation needed]" tag to an image. The coordinates may need adjustment.
7883 /usr/local/bin/convert - -pointsize 16 -fill white -annotate +17+418 "[citation needed]" -
7888 Currently external filters are executed with &my-app;'s privileges!
7889 Only use external filters you understand and trust.
7893 External filters are experimental and the syntax may change in the future.
7899 <!-- ~ End section ~ -->
7903 <!-- ~~~~~ New section ~~~~~ -->
7905 <sect1 id="templates">
7906 <title>Privoxy's Template Files</title>
7908 All <application>Privoxy</application> built-in pages, i.e. error pages such as the
7909 <ulink url="http://show-the-404-error.page"><quote>404 - No Such Domain</quote>
7910 error page</ulink>, the <ulink
7911 url="http://ads.bannerserver.example.com/nasty-ads/sponsor.html"><quote>BLOCKED</quote>
7913 and all pages of its <ulink url="http://config.privoxy.org/">web-based
7914 user interface</ulink>, are generated from <emphasis>templates</emphasis>.
7915 (<application>Privoxy</application> must be running for the above links to work as
7920 These templates are stored in a subdirectory of the <link linkend="confdir">configuration
7921 directory</link> called <filename>templates</filename>. On Unixish platforms,
7923 <ulink url="file:///etc/privoxy/templates/"><filename>/etc/privoxy/templates/</filename></ulink>.
7927 The templates are basically normal HTML files, but with place-holders (called symbols
7928 or exports), which <application>Privoxy</application> fills at run time. It
7929 is possible to edit the templates with a normal text editor, should you want
7930 to customize them. (<emphasis>Not recommended for the casual
7931 user</emphasis>). Should you create your own custom templates, you should use
7932 the <filename>config</filename> setting <link linkend="templdir">templdir</link>
7933 to specify an alternate location, so your templates do not get overwritten
7937 Note that just like in configuration files, lines starting
7938 with <literal>#</literal> are ignored when the templates are filled in.
7942 The place-holders are of the form <literal>@name@</literal>, and you will
7943 find a list of available symbols, which vary from template to template,
7944 in the comments at the start of each file. Note that these comments are not
7945 always accurate, and that it's probably best to look at the existing HTML
7946 code to find out which symbols are supported and what they are filled in with.
7950 A special application of this substitution mechanism is to make whole
7951 blocks of HTML code disappear when a specific symbol is set. We use this
7952 for many purposes, one of them being to include the beta warning in all
7953 our user interface (CGI) pages when <application>Privoxy</application>
7954 is in an alpha or beta development stage:
7958 <!-- @if-unstable-start -->
7960 ... beta warning HTML code goes here ...
7962 <!-- if-unstable-end@ --></screen>
7965 If the "unstable" symbol is set, everything in between and including
7966 <literal>@if-unstable-start</literal> and <literal>if-unstable-end@</literal>
7967 will disappear, leaving nothing but an empty comment:
7970 <screen><!-- --></screen>
7973 There's also an if-then-else construct and an <literal>#include</literal>
7974 mechanism, but you'll sure find out if you are inclined to edit the
7979 All templates refer to a style located at
7980 <ulink url="http://config.privoxy.org/send-stylesheet"><literal>http://config.privoxy.org/send-stylesheet</literal></ulink>.
7981 This is, of course, locally served by <application>Privoxy</application>
7982 and the source for it can be found and edited in the
7983 <filename>cgi-style.css</filename> template.
7988 <!-- ~ End section ~ -->
7992 <!-- ~~~~~ New section ~~~~~ -->
7994 <sect1 id="contact"><title>Contacting the Developers, Bug Reporting and Feature
7997 <!-- Include contacting.sgml boilerplate: -->
7999 <!-- end boilerplate -->
8003 <!-- ~ End section ~ -->
8006 <!-- ~~~~~ New section ~~~~~ -->
8007 <sect1 id="copyright"><title>Privoxy Copyright, License and History</title>
8009 <!-- Include copyright.sgml: -->
8011 <!-- end copyright -->
8014 <application>Privoxy</application> is free software; you can
8015 redistribute and/or modify its source code under the terms
8016 of the <citetitle>GNU General Public License</citetitle>
8017 as published by the Free Software Foundation, either version 2
8018 of the license, or (at your option) any later version.
8022 The same is true for <application>Privoxy</application> binaries
8023 unless they are linked with a
8024 <ulink url="https://tls.mbed.org/">mbed TLS</ulink> version
8025 that is licensed under the Apache 2.0 license in which
8026 case you can redistribute and/or modify the <application>Privoxy</application>
8027 binaries under the terms of the <citetitle>GNU General Public License</citetitle>
8028 as published by the Free Software Foundation, either version 3
8029 of the license, or (at your option) any later version.
8033 Both licenses are included in the next section.
8036 <!-- ~~~~~ New section ~~~~~ -->
8037 <sect2 id="license"><title>License</title>
8039 <sect3 id="gplv2"><title>GNU General Public License version 2</title>
8040 <screen><![ RCDATA [ &GPLv2; ]]></screen>
8043 <sect3 id="gplv3"><title>GNU General Public License version 3</title>
8044 <screen><![ RCDATA [ &GPLv3; ]]></screen>
8047 <sect3 id="third-party-licenses"><title>Third-party licenses and copyrights</title>
8049 Privoxy depends on a couple of third-party libraries which have seperate licenses.
8050 Please refer to the third-party websites for up-to-date license and copyright
8054 Privoxy depends on <ulink url="https://pcre.org/">pcre</ulink>.
8057 When compiled with FEATURE_BROTLI (optional), Privoxy depends on
8058 <ulink url="https://www.brotli.org/">brotli</ulink>.
8061 When compiled with FEATURE_HTTPS_INSPECTION (optional),
8062 Privoxy depends on a TLS library. The supported libraries are
8063 <ulink url="https://www.openssl.org/">LibreSSL</ulink>,
8064 <ulink url="https://tls.mbed.org/">mbed TLS</ulink> and
8065 <ulink url="https://www.openssl.org/">OpenSSL</ulink>.
8068 When compiled with FEATURE_ZLIB (optional),
8069 Privoxy depends on <ulink url="https://zlib.net/">zlib</ulink>.
8074 <!-- ~ End section ~ -->
8077 <!-- ~~~~~ New section ~~~~~ -->
8079 <sect2 id="history"><title>History</title>
8080 <!-- Include history.sgml: -->
8082 <!-- end history -->
8085 <sect2 id="authors"><title>Authors</title>
8086 <!-- Include p-authors.sgml: -->
8088 <!-- end authors -->
8093 <!-- ~ End section ~ -->
8096 <!-- ~~~~~ New section ~~~~~ -->
8097 <sect1 id="seealso"><title>See Also</title>
8098 <!-- Include seealso.sgml: -->
8100 <!-- end seealso -->
8105 <!-- ~~~~~ New section ~~~~~ -->
8106 <sect1 id="appendix"><title>Appendix</title>
8109 <!-- ~~~~~ New section ~~~~~ -->
8111 <title>Regular Expressions</title>
8113 <application>Privoxy</application> uses Perl-style <quote>regular
8114 expressions</quote> in its <link linkend="actions-file">actions
8115 files</link> and <link linkend="filter-file">filter file</link>,
8116 through the <ulink url="http://www.pcre.org/">PCRE</ulink> and
8119 <ulink url="http://www.oesterhelt.org/pcrs/">PCRS</ulink> libraries.
8121 <application>PCRS</application> libraries.
8125 If you are reading this, you probably don't understand what <quote>regular
8126 expressions</quote> are, or what they can do. So this will be a very brief
8127 introduction only. A full explanation would require a <ulink
8128 url="http://www.oreilly.com/catalog/regex/">book</ulink> ;-)
8132 Regular expressions provide a language to describe patterns that can be
8133 run against strings of characters (letter, numbers, etc), to see if they
8134 match the string or not. The patterns are themselves (sometimes complex)
8135 strings of literal characters, combined with wild-cards, and other special
8136 characters, called meta-characters. The <quote>meta-characters</quote> have
8137 special meanings and are used to build complex patterns to be matched against.
8138 Perl Compatible Regular Expressions are an especially convenient
8139 <quote>dialect</quote> of the regular expression language.
8143 To make a simple analogy, we do something similar when we use wild-card
8144 characters when listing files with the <command>dir</command> command in DOS.
8145 <literal>*.*</literal> matches all filenames. The <quote>special</quote>
8146 character here is the asterisk which matches any and all characters. We can be
8147 more specific and use <literal>?</literal> to match just individual
8148 characters. So <quote>dir file?.text</quote> would match
8149 <quote>file1.txt</quote>, <quote>file2.txt</quote>, etc. We are pattern
8150 matching, using a similar technique to <quote>regular expressions</quote>!
8154 Regular expressions do essentially the same thing, but are much, much more
8155 powerful. There are many more <quote>special characters</quote> and ways of
8156 building complex patterns however. Let's look at a few of the common ones,
8157 and then some examples:
8162 <emphasis>.</emphasis> - Matches any single character, e.g. <quote>a</quote>,
8163 <quote>A</quote>, <quote>4</quote>, <quote>:</quote>, or <quote>@</quote>.
8169 <emphasis>?</emphasis> - The preceding character or expression is matched ZERO or ONE
8176 <emphasis>+</emphasis> - The preceding character or expression is matched ONE or MORE
8183 <emphasis>*</emphasis> - The preceding character or expression is matched ZERO or MORE
8190 <emphasis>\</emphasis> - The <quote>escape</quote> character denotes that
8191 the following character should be taken literally. This is used where one of the
8192 special characters (e.g. <quote>.</quote>) needs to be taken literally and
8193 not as a special meta-character. Example: <quote>example\.com</quote>, makes
8194 sure the period is recognized only as a period (and not expanded to its
8195 meta-character meaning of any single character).
8201 <emphasis>[ ]</emphasis> - Characters enclosed in brackets will be matched if
8202 any of the enclosed characters are encountered. For instance, <quote>[0-9]</quote>
8203 matches any numeric digit (zero through nine). As an example, we can combine
8204 this with <quote>+</quote> to match any digit one of more times: <quote>[0-9]+</quote>.
8210 <emphasis>( )</emphasis> - parentheses are used to group a sub-expression,
8211 or multiple sub-expressions.
8217 <emphasis>|</emphasis> - The <quote>bar</quote> character works like an
8218 <quote>or</quote> conditional statement. A match is successful if the
8219 sub-expression on either side of <quote>|</quote> matches. As an example:
8220 <quote>/(this|that) example/</quote> uses grouping and the bar character
8221 and would match either <quote>this example</quote> or <quote>that
8222 example</quote>, and nothing else.
8227 These are just some of the ones you are likely to use when matching URLs with
8228 <application>Privoxy</application>, and is a long way from a definitive
8229 list. This is enough to get us started with a few simple examples which may
8230 be more illuminating:
8234 <emphasis><literal>/.*/banners/.*</literal></emphasis> - A simple example
8235 that uses the common combination of <quote>.</quote> and <quote>*</quote> to
8236 denote any character, zero or more times. In other words, any string at all.
8237 So we start with a literal forward slash, then our regular expression pattern
8238 (<quote>.*</quote>) another literal forward slash, the string
8239 <quote>banners</quote>, another forward slash, and lastly another
8240 <quote>.*</quote>. We are building
8241 a directory path here. This will match any file with the path that has a
8242 directory named <quote>banners</quote> in it. The <quote>.*</quote> matches
8243 any characters, and this could conceivably be more forward slashes, so it
8244 might expand into a much longer looking path. For example, this could match:
8245 <quote>/eye/hate/spammers/banners/annoy_me_please.gif</quote>, or just
8246 <quote>/banners/annoying.html</quote>, or almost an infinite number of other
8247 possible combinations, just so it has <quote>banners</quote> in the path
8252 And now something a little more complex:
8256 <emphasis><literal>/.*/adv((er)?ts?|ertis(ing|ements?))?/</literal></emphasis> -
8257 We have several literal forward slashes again (<quote>/</quote>), so we are
8258 building another expression that is a file path statement. We have another
8259 <quote>.*</quote>, so we are matching against any conceivable sub-path, just so
8260 it matches our expression. The only true literal that <emphasis>must
8261 match</emphasis> our pattern is <application>adv</application>, together with
8262 the forward slashes. What comes after the <quote>adv</quote> string is the
8267 Remember the <quote>?</quote> means the preceding expression (either a
8268 literal character or anything grouped with <quote>(...)</quote> in this case)
8269 can exist or not, since this means either zero or one match. So
8270 <quote>((er)?ts?|ertis(ing|ements?))</quote> is optional, as are the
8271 individual sub-expressions: <quote>(er)</quote>,
8272 <quote>(ing|ements?)</quote>, and the <quote>s</quote>. The <quote>|</quote>
8273 means <quote>or</quote>. We have two of those. For instance,
8274 <quote>(ing|ements?)</quote>, can expand to match either <quote>ing</quote>
8275 <emphasis>OR</emphasis> <quote>ements?</quote>. What is being done here, is an
8276 attempt at matching as many variations of <quote>advertisement</quote>, and
8277 similar, as possible. So this would expand to match just <quote>adv</quote>,
8278 or <quote>advert</quote>, or <quote>adverts</quote>, or
8279 <quote>advertising</quote>, or <quote>advertisement</quote>, or
8280 <quote>advertisements</quote>. You get the idea. But it would not match
8281 <quote>advertizements</quote> (with a <quote>z</quote>). We could fix that by
8282 changing our regular expression to:
8283 <quote>/.*/adv((er)?ts?|erti(s|z)(ing|ements?))?/</quote>, which would then match
8288 <emphasis><literal>/.*/advert[0-9]+\.(gif|jpe?g)</literal></emphasis> - Again
8289 another path statement with forward slashes. Anything in the square brackets
8290 <quote>[ ]</quote> can be matched. This is using <quote>0-9</quote> as a
8291 shorthand expression to mean any digit one through nine. It is the same as
8292 saying <quote>0123456789</quote>. So any digit matches. The <quote>+</quote>
8293 means one or more of the preceding expression must be included. The preceding
8294 expression here is what is in the square brackets -- in this case, any digit
8295 one through nine. Then, at the end, we have a grouping: <quote>(gif|jpe?g)</quote>.
8296 This includes a <quote>|</quote>, so this needs to match the expression on
8297 either side of that bar character also. A simple <quote>gif</quote> on one side, and the other
8298 side will in turn match either <quote>jpeg</quote> or <quote>jpg</quote>,
8299 since the <quote>?</quote> means the letter <quote>e</quote> is optional and
8300 can be matched once or not at all. So we are building an expression here to
8301 match image GIF or JPEG type image file. It must include the literal
8302 string <quote>advert</quote>, then one or more digits, and a <quote>.</quote>
8303 (which is now a literal, and not a special character, since it is escaped
8304 with <quote>\</quote>), and lastly either <quote>gif</quote>, or
8305 <quote>jpeg</quote>, or <quote>jpg</quote>. Some possible matches would
8306 include: <quote>//advert1.jpg</quote>,
8307 <quote>/nasty/ads/advert1234.gif</quote>,
8308 <quote>/banners/from/hell/advert99.jpg</quote>. It would not match
8309 <quote>advert1.gif</quote> (no leading slash), or
8310 <quote>/adverts232.jpg</quote> (the expression does not include an
8311 <quote>s</quote>), or <quote>/advert1.jsp</quote> (<quote>jsp</quote> is not
8312 in the expression anywhere).
8316 We are barely scratching the surface of regular expressions here so that you
8317 can understand the default <application>Privoxy</application>
8318 configuration files, and maybe use this knowledge to customize your own
8319 installation. There is much, much more that can be done with regular
8320 expressions. Now that you know enough to get started, you can learn more on
8325 More reading on Perl Compatible Regular expressions:
8326 <ulink url="http://perldoc.perl.org/perlre.html">http://perldoc.perl.org/perlre.html</ulink>
8330 For information on regular expression based substitutions and their applications
8331 in filters, please see the <link linkend="filter-file">filter file tutorial</link>
8336 <!-- ~ End section ~ -->
8339 <!-- ~~~~~ New section ~~~~~ -->
8340 <sect2 id="internal-pages">
8341 <title>Privoxy's Internal Pages</title>
8344 Since <application>Privoxy</application> proxies each requested
8345 web page, it is easy for <application>Privoxy</application> to
8346 trap certain special URLs. In this way, we can talk directly to
8347 <application>Privoxy</application>, and see how it is
8348 configured, see how our rules are being applied, change these
8349 rules and other configuration options, and even turn
8350 <application>Privoxy's</application> filtering off, all with
8355 The URLs listed below are the special ones that allow direct access
8356 to <application>Privoxy</application>. Of course,
8357 <application>Privoxy</application> must be running to access these. If
8358 not, you will get a friendly error message. Internet access is not
8370 <ulink url="http://config.privoxy.org/">http://config.privoxy.org/</ulink>
8374 There is a shortcut: <ulink url="http://p.p/">http://p.p/</ulink> (But it
8375 doesn't provide a fall-back to a real page, in case the request is not
8376 sent through <application>Privoxy</application>)
8382 View and toggle client tags:
8386 <ulink url="http://config.privoxy.org/client-tags">http://config.privoxy.org/client-tags</ulink>
8393 Show information about the current configuration, including viewing and
8394 editing of actions files:
8398 <ulink url="http://config.privoxy.org/show-status">http://config.privoxy.org/show-status</ulink>
8405 Show the browser's request headers:
8409 <ulink url="http://config.privoxy.org/show-request">http://config.privoxy.org/show-request</ulink>
8416 Show which actions apply to a URL and why:
8420 <ulink url="http://config.privoxy.org/show-url-info">http://config.privoxy.org/show-url-info</ulink>
8427 Toggle Privoxy on or off. This feature can be turned off/on in the main
8428 <filename>config</filename> file. When toggled <quote>off</quote>, <quote>Privoxy</quote>
8429 continues to run, but only as a pass-through proxy, with no actions taking
8434 <ulink url="http://config.privoxy.org/toggle">http://config.privoxy.org/toggle</ulink>
8438 Short cuts. Turn off, then on:
8442 <ulink url="http://config.privoxy.org/toggle?set=disable">http://config.privoxy.org/toggle?set=disable</ulink>
8447 <ulink url="http://config.privoxy.org/toggle?set=enable">http://config.privoxy.org/toggle?set=enable</ulink>
8457 <!-- ~~~~~ New section ~~~~~ -->
8459 <title>Chain of Events</title>
8461 Let's take a quick look at how some of <application>Privoxy's</application>
8462 core features are triggered, and the ensuing sequence of events when a web
8463 page is requested by your browser:
8469 First, your web browser requests a web page. The browser knows to send
8470 the request to <application>Privoxy</application>, which will in turn,
8471 relay the request to the remote web server after passing the following
8477 <application>Privoxy</application> traps any request for its own internal CGI
8478 pages (e.g <ulink url="http://p.p/">http://p.p/</ulink>) and sends the CGI page back to the browser.
8483 Next, <application>Privoxy</application> checks to see if the URL
8485 linkend="BLOCK"><quote>+block</quote></link> patterns. If
8486 so, the URL is then blocked, and the remote web server will not be contacted.
8487 <link linkend="HANDLE-AS-IMAGE"><quote>+handle-as-image</quote></link>
8489 <link linkend="HANDLE-AS-EMPTY-DOCUMENT"><quote>+handle-as-empty-document</quote></link>
8490 are then checked, and if there is no match, an
8491 HTML <quote>BLOCKED</quote> page is sent back to the browser. Otherwise, if
8492 it does match, an image is returned for the former, and an empty text
8493 document for the latter. The type of image would depend on the setting of
8494 <link linkend="SET-IMAGE-BLOCKER"><quote>+set-image-blocker</quote></link>
8495 (blank, checkerboard pattern, or an HTTP redirect to an image elsewhere).
8500 Untrusted URLs are blocked. If URLs are being added to the
8501 <filename>trust</filename> file, then that is done.
8506 If the URL pattern matches the <link
8507 linkend="FAST-REDIRECTS"><quote>+fast-redirects</quote></link> action,
8508 it is then processed. Unwanted parts of the requested URL are stripped.
8513 Now the rest of the client browser's request headers are processed. If any
8514 of these match any of the relevant actions (e.g. <link
8515 linkend="HIDE-USER-AGENT"><quote>+hide-user-agent</quote></link>,
8516 etc.), headers are suppressed or forged as determined by these actions and
8522 Now the web server starts sending its response back (i.e. typically a web
8528 First, the server headers are read and processed to determine, among other
8529 things, the MIME type (document type) and encoding. The headers are then
8530 filtered as determined by the
8531 <link linkend="CRUNCH-INCOMING-COOKIES"><quote>+crunch-incoming-cookies</quote></link>,
8532 <link linkend="SESSION-COOKIES-ONLY"><quote>+session-cookies-only</quote></link>,
8533 and <link linkend="DOWNGRADE-HTTP-VERSION"><quote>+downgrade-http-version</quote></link>
8539 If any <link linkend="FILTER"><quote>+filter</quote></link> action
8541 linkend="DEANIMATE-GIFS"><quote>+deanimate-gifs</quote></link>
8542 action applies (and the document type fits the action), the rest of the page is
8543 read into memory (up to a configurable limit). Then the filter rules (from
8544 <filename>default.filter</filename> and any other filter files) are
8545 processed against the buffered content. Filters are applied in the order
8546 they are specified in one of the filter files. Animated GIFs, if present,
8547 are reduced to either the first or last frame, depending on the action
8548 setting.The entire page, which is now filtered, is then sent by
8549 <application>Privoxy</application> back to your browser.
8552 If neither a <link linkend="FILTER"><quote>+filter</quote></link> action
8554 linkend="DEANIMATE-GIFS"><quote>+deanimate-gifs</quote></link>
8555 matches, then <application>Privoxy</application> passes the raw data through
8556 to the client browser as it becomes available.
8561 As the browser receives the now (possibly filtered) page content, it
8562 reads and then requests any URLs that may be embedded within the page
8563 source, e.g. ad images, stylesheets, JavaScript, other HTML documents (e.g.
8564 frames), sounds, etc. For each of these objects, the browser issues a
8565 separate request (this is easily viewable in <application>Privoxy's</application>
8566 logs). And each such request is in turn processed just as above. Note that a
8567 complex web page will have many, many such embedded URLs. If these
8568 secondary requests are to a different server, then quite possibly a very
8569 differing set of actions is triggered.
8576 NOTE: This is somewhat of a simplistic overview of what happens with each URL
8577 request. For the sake of brevity and simplicity, we have focused on
8578 <application>Privoxy's</application> core features only.
8584 <!-- ~~~~~ New section ~~~~~ -->
8585 <sect2 id="actionsanat">
8586 <title>Troubleshooting: Anatomy of an Action</title>
8589 The way <application>Privoxy</application> applies
8590 <link linkend="ACTIONS">actions</link> and <link linkend="FILTER">filters</link>
8591 to any given URL can be complex, and not always so
8592 easy to understand what is happening. And sometimes we need to be able to
8593 <emphasis>see</emphasis> just what <application>Privoxy</application> is
8594 doing. Especially, if something <application>Privoxy</application> is doing
8595 is causing us a problem inadvertently. It can be a little daunting to look at
8596 the actions and filters files themselves, since they tend to be filled with
8597 <link linkend="regex">regular expressions</link> whose consequences are not
8602 One quick test to see if <application>Privoxy</application> is causing a problem
8603 or not, is to disable it temporarily. This should be the first troubleshooting
8604 step (be sure to flush caches afterward!). Looking at the
8605 logs is a good idea too. (Note that both the toggle feature and logging are
8606 enabled via <filename>config</filename> file settings, and may need to be
8607 turned <quote>on</quote>.)
8610 Another easy troubleshooting step to try is if you have done any
8611 customization of your installation, revert back to the installed
8612 defaults and see if that helps. There are times the developers get complaints
8613 about one thing or another, and the problem is more related to a customized
8614 configuration issue.
8618 <application>Privoxy</application> also provides the
8619 <ulink url="http://config.privoxy.org/show-url-info">http://config.privoxy.org/show-url-info</ulink>
8620 page that can show us very specifically how <application>actions</application>
8621 are being applied to any given URL. This is a big help for troubleshooting.
8625 First, enter one URL (or partial URL) at the prompt, and then
8626 <application>Privoxy</application> will tell us
8627 how the current configuration will handle it. This will not
8628 help with filtering effects (i.e. the <link
8629 linkend="FILTER"><quote>+filter</quote></link> action) from
8630 one of the filter files since this is handled very
8631 differently and not so easy to trap! It also will not tell you about any other
8632 URLs that may be embedded within the URL you are testing. For instance, images
8633 such as ads are expressed as URLs within the raw page source of HTML pages. So
8634 you will only get info for the actual URL that is pasted into the prompt area
8635 -- not any sub-URLs. If you want to know about embedded URLs like ads, you
8636 will have to dig those out of the HTML source. Use your browser's <quote>View
8637 Page Source</quote> option for this. Or right click on the ad, and grab the
8642 Let's try an example, <ulink url="http://google.com">google.com</ulink>,
8643 and look at it one section at a time in a sample configuration (your real
8644 configuration may vary):
8648 Matches for http://www.google.com:
8650 In file: default.action <guibutton>[ View ]</guibutton> <guibutton>[ Edit ]</guibutton>
8652 {+change-x-forwarded-for{block}
8653 +deanimate-gifs {last}
8654 +fast-redirects {check-decoded-url}
8655 +filter {refresh-tags}
8656 +filter {img-reorder}
8657 +filter {banners-by-size}
8659 +filter {jumping-windows}
8660 +filter {ie-exploits}
8661 +hide-from-header {block}
8662 +hide-referrer {forge}
8663 +session-cookies-only
8664 +set-image-blocker {pattern}
8667 { -session-cookies-only }
8673 In file: user.action <guibutton>[ View ]</guibutton> <guibutton>[ Edit ]</guibutton>
8674 (no matches in this file)
8678 This is telling us how we have defined our
8679 <link linkend="ACTIONS"><quote>actions</quote></link>, and
8680 which ones match for our test case, <quote>google.com</quote>.
8681 Displayed is all the actions that are available to us. Remember,
8682 the <literal>+</literal> sign denotes <quote>on</quote>. <literal>-</literal>
8683 denotes <quote>off</quote>. So some are <quote>on</quote> here, but many
8684 are <quote>off</quote>. Each example we try may provide a slightly different
8685 end result, depending on our configuration directives.
8689 is for our <filename>default.action</filename> file. The large, multi-line
8690 listing, is how the actions are set to match for all URLs, i.e. our default
8691 settings. If you look at your <quote>actions</quote> file, this would be the
8692 section just below the <quote>aliases</quote> section near the top. This
8693 will apply to all URLs as signified by the single forward slash at the end
8694 of the listing -- <quote> / </quote>.
8698 But we have defined additional actions that would be exceptions to these general
8699 rules, and then we list specific URLs (or patterns) that these exceptions
8700 would apply to. Last match wins. Just below this then are two explicit
8701 matches for <quote>.google.com</quote>. The first is negating our previous
8702 cookie setting, which was for <link
8703 linkend="SESSION-COOKIES-ONLY"><quote>+session-cookies-only</quote></link>
8704 (i.e. not persistent). So we will allow persistent cookies for google, at
8705 least that is how it is in this example. The second turns
8706 <emphasis>off</emphasis> any <link
8707 linkend="FAST-REDIRECTS"><quote>+fast-redirects</quote></link>
8708 action, allowing this to take place unmolested. Note that there is a leading
8709 dot here -- <quote>.google.com</quote>. This will match any hosts and
8710 sub-domains, in the google.com domain also, such as
8711 <quote>www.google.com</quote> or <quote>mail.google.com</quote>. But it would not
8712 match <quote>www.google.de</quote>! So, apparently, we have these two actions
8713 defined as exceptions to the general rules at the top somewhere in the lower
8714 part of our <filename>default.action</filename> file, and
8715 <quote>google.com</quote> is referenced somewhere in these latter sections.
8719 Then, for our <filename>user.action</filename> file, we again have no hits.
8720 So there is nothing google-specific that we might have added to our own, local
8721 configuration. If there was, those actions would over-rule any actions from
8722 previously processed files, such as <filename>default.action</filename>.
8723 <filename>user.action</filename> typically has the last word. This is the
8724 best place to put hard and fast exceptions,
8728 And finally we pull it all together in the bottom section and summarize how
8729 <application>Privoxy</application> is applying all its <quote>actions</quote>
8730 to <quote>google.com</quote>:
8738 +change-x-forwarded-for{block}
8739 -client-header-filter{hide-tor-exit-notation}
8740 -content-type-overwrite
8741 -crunch-client-header
8742 -crunch-if-none-match
8743 -crunch-incoming-cookies
8744 -crunch-outgoing-cookies
8745 -crunch-server-header
8746 +deanimate-gifs {last}
8747 -downgrade-http-version
8750 -filter {content-cookies}
8751 -filter {all-popups}
8752 -filter {banners-by-link}
8753 -filter {tiny-textforms}
8754 -filter {frameset-borders}
8755 -filter {demoronizer}
8756 -filter {shockwave-flash}
8757 -filter {quicktime-kioskmode}
8759 -filter {crude-parental}
8760 -filter {site-specifics}
8761 -filter {js-annoyances}
8762 -filter {html-annoyances}
8763 +filter {refresh-tags}
8764 -filter {unsolicited-popups}
8765 +filter {img-reorder}
8766 +filter {banners-by-size}
8768 +filter {jumping-windows}
8769 +filter {ie-exploits}
8776 -handle-as-empty-document
8778 -hide-accept-language
8779 -hide-content-disposition
8780 +hide-from-header {block}
8781 -hide-if-modified-since
8782 +hide-referrer {forge}
8785 -overwrite-last-modified
8786 -prevent-compression
8788 -server-header-filter{xml-to-html}
8789 -server-header-filter{html-to-xml}
8790 -session-cookies-only
8791 +set-image-blocker {pattern}
8795 Notice the only difference here to the previous listing, is to
8796 <quote>fast-redirects</quote> and <quote>session-cookies-only</quote>,
8797 which are activated specifically for this site in our configuration,
8798 and thus show in the <quote>Final Results</quote>.
8802 Now another example, <quote>ad.doubleclick.net</quote>:
8806 { +block{Domains starts with "ad"} }
8809 { +block{Domain contains "ad"} }
8812 { +block{Doubleclick banner server} +handle-as-image }
8813 .[a-vx-z]*.doubleclick.net
8817 We'll just show the interesting part here - the explicit matches. It is
8818 matched three different times. Two <quote>+block{}</quote> sections,
8819 and a <quote>+block{} +handle-as-image</quote>,
8820 which is the expanded form of one of our aliases that had been defined as:
8821 <quote>+block-as-image</quote>. (<link
8822 linkend="ALIASES"><quote>Aliases</quote></link> are defined in
8823 the first section of the actions file and typically used to combine more
8828 Any one of these would have done the trick and blocked this as an unwanted
8829 image. This is unnecessarily redundant since the last case effectively
8830 would also cover the first. No point in taking chances with these guys
8831 though ;-) Note that if you want an ad or obnoxious
8832 URL to be invisible, it should be defined as <quote>ad.doubleclick.net</quote>
8833 is done here -- as both a <link
8834 linkend="BLOCK"><quote>+block{}</quote></link>
8835 <emphasis>and</emphasis> an
8836 <link linkend="HANDLE-AS-IMAGE"><quote>+handle-as-image</quote></link>.
8837 The custom alias <quote><literal>+block-as-image</literal></quote> just
8838 simplifies the process and make it more readable.
8842 One last example. Let's try <quote>http://www.example.net/adsl/HOWTO/</quote>.
8843 This one is giving us problems. We are getting a blank page. Hmmm ...
8847 Matches for http://www.example.net/adsl/HOWTO/:
8849 In file: default.action <guibutton>[ View ]</guibutton> <guibutton>[ Edit ]</guibutton>
8853 +change-x-forwarded-for{block}
8854 -client-header-filter{hide-tor-exit-notation}
8855 -content-type-overwrite
8856 -crunch-client-header
8857 -crunch-if-none-match
8858 -crunch-incoming-cookies
8859 -crunch-outgoing-cookies
8860 -crunch-server-header
8862 -downgrade-http-version
8863 +fast-redirects {check-decoded-url}
8865 -filter {content-cookies}
8866 -filter {all-popups}
8867 -filter {banners-by-link}
8868 -filter {tiny-textforms}
8869 -filter {frameset-borders}
8870 -filter {demoronizer}
8871 -filter {shockwave-flash}
8872 -filter {quicktime-kioskmode}
8874 -filter {crude-parental}
8875 -filter {site-specifics}
8876 -filter {js-annoyances}
8877 -filter {html-annoyances}
8878 +filter {refresh-tags}
8879 -filter {unsolicited-popups}
8880 +filter {img-reorder}
8881 +filter {banners-by-size}
8883 +filter {jumping-windows}
8884 +filter {ie-exploits}
8891 -handle-as-empty-document
8893 -hide-accept-language
8894 -hide-content-disposition
8895 +hide-from-header{block}
8896 +hide-referer{forge}
8898 -overwrite-last-modified
8899 +prevent-compression
8901 -server-header-filter{xml-to-html}
8902 -server-header-filter{html-to-xml}
8903 +session-cookies-only
8904 +set-image-blocker{blank} }
8907 { +block{Path contains "ads".} +handle-as-image }
8912 Ooops, the <quote>/adsl/</quote> is matching <quote>/ads</quote> in our
8913 configuration! But we did not want this at all! Now we see why we get the
8914 blank page. It is actually triggering two different actions here, and
8915 the effects are aggregated so that the URL is blocked, and &my-app; is told
8916 to treat the block as if it were an image. But this is, of course, all wrong.
8917 We could now add a new action below this (or better in our own
8918 <filename>user.action</filename> file) that explicitly
8919 <emphasis>un</emphasis> blocks (
8920 <link linkend="BLOCK"><quote>{-block}</quote></link>) paths with
8921 <quote>adsl</quote> in them (remember, last match in the configuration
8922 wins). There are various ways to handle such exceptions. Example:
8931 Now the page displays ;-)
8932 Remember to flush your browser's caches when making these kinds of changes to
8933 your configuration to insure that you get a freshly delivered page! Or, try
8934 using <literal>Shift+Reload</literal>.
8938 But now what about a situation where we get no explicit matches like
8943 { +block{Path starts with "ads".} +handle-as-image }
8948 That actually was very helpful and pointed us quickly to where the problem
8949 was. If you don't get this kind of match, then it means one of the default
8950 rules in the first section of <filename>default.action</filename> is causing
8951 the problem. This would require some guesswork, and maybe a little trial and
8952 error to isolate the offending rule. One likely cause would be one of the
8953 <link linkend="FILTER"><quote>+filter</quote></link> actions.
8954 These tend to be harder to troubleshoot.
8955 Try adding the URL for the site to one of aliases that turn off
8956 <link linkend="FILTER"><quote>+filter</quote></link>:
8962 .worldpay.com # for quietpc.com
8969 <quote><literal>{ shop }</literal></quote> is an <quote>alias</quote> that expands to
8970 <quote><literal>{ -filter -session-cookies-only }</literal></quote>.
8971 Or you could do your own exception to negate filtering:
8976 # Disable ALL filter actions for sites in this section
8983 This would turn off all filtering for these sites. This is best
8984 put in <filename>user.action</filename>, for local site
8985 exceptions. Note that when a simple domain pattern is used by itself (without
8986 the subsequent path portion), all sub-pages within that domain are included
8987 automatically in the scope of the action.
8991 Images that are inexplicably being blocked, may well be hitting the
8992 <link linkend="FILTER-BANNERS-BY-SIZE"><quote>+filter{banners-by-size}</quote></link>
8994 that images of certain sizes are ad banners (works well
8995 <emphasis>most of the time</emphasis> since these tend to be standardized).
8999 <quote><literal>{ fragile }</literal></quote> is an alias that disables most
9000 actions that are the most likely to cause trouble. This can be used as a
9001 last resort for problem sites.
9006 # Handle with care: easy to break
9008 mybank.example.com</screen>
9012 <emphasis>Remember to flush caches!</emphasis> Note that the
9013 <literal>mail.google</literal> reference lacks the TLD portion (e.g.
9014 <quote>.com</quote>). This will effectively match any TLD with
9015 <literal>google</literal> in it, such as <literal>mail.google.de.</literal>,
9019 If this still does not work, you will have to go through the remaining
9020 actions one by one to find which one(s) is causing the problem.
9029 This program is free software; you can redistribute it
9030 and/or modify it under the terms of the GNU General
9031 Public License as published by the Free Software
9032 Foundation; either version 2 of the License, or (at
9033 your option) any later version.
9035 This program is distributed in the hope that it will
9036 be useful, but WITHOUT ANY WARRANTY; without even the
9037 implied warranty of MERCHANTABILITY or FITNESS FOR A
9038 PARTICULAR PURPOSE. See the GNU General Public
9039 License for more details.
9041 The GNU General Public License should be included with
9042 this file. If not, you can view it at
9043 http://www.gnu.org/copyleft/gpl.html
9044 or write to the Free Software Foundation, Inc.,
9045 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,