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4 <!entity newfeatures SYSTEM "newfeatures.sgml">
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6 <!entity seealso SYSTEM "seealso.sgml">
7 <!entity buildsource SYSTEM "buildsource.sgml">
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10 <!entity copyright SYSTEM "copyright.sgml">
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13 <!entity GPLv3 SYSTEM "../../LICENSE.GPLv3">
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16 <!entity changelog SYSTEM "changelog.sgml">
17 <!entity p-version "3.0.30">
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 -->
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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 -->
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31 <!entity my-app "<application>Privoxy</application>">
34 File : doc/source/user-manual.sgml
38 Copyright (C) 2001-2020 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; 2001-2020 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 windows/GNUmakefile to set the location of the NSIS executable - eg:
406 MAKENSIS = ./nsis/makensis.exe
411 <sect4 id="WINBUILD-BUILD"><title>Build</title>
414 To build just the Privoxy executable and not the whole installation package, do:
417 cd <root-dir>/privoxy
418 ./windows/MYconfigure && make
422 Privoxy uses the <ulink url="https://en.wikipedia.org/wiki/GNU_build_system">GNU Autotools</ulink>
423 for building software, so the process is:
426 $ autoheader # creates config.h.in
427 $ autoconf # uses config.h.in to create the configure shell script
428 $ ./configure [options] # creates GNUmakefile
429 $ make [options] # builds the program
433 The usual <literal>configure</literal> options for building a native Windows application under cygwin are
436 <literallayout class="Monospaced">
437 --host=i686-w64-mingw32
440 --enable-static-linking
442 --disable-dynamic-pcre
446 You can set the <literal>CFLAGS</literal> and <literal>LDFLAGS</literal> envars before
447 running <literal>configure</literal> to set compiler and linker flags. For example:
451 $ export CFLAGS="-O2" # set gcc optimization level
452 $ export LDFLAGS="-Wl,--nxcompat" # Enable DEP
453 $ ./configure --host=i686-w64-mingw32 --enable-mingw32 --enable-zlib \
454 > --enable-static-linking --disable-pthread --disable-dynamic-pcre
455 $ make # build Privoxy
459 See the <ulink url="../developer-manual/newrelease.html#NEWRELEASE-WINDOWS">Developer's Manual</ulink>
460 for building a Windows release package.
468 <!-- ~~~~~ New section ~~~~~ -->
469 <sect2 id="installation-keepupdated"><title>Keeping your Installation Up-to-Date</title>
472 If you wish to receive an email notification whenever we release updates of
473 <application>Privoxy</application> or the actions file, <ulink
474 url="https://lists.privoxy.org/mailman/listinfo/privoxy-announce">subscribe
475 to our announce mailing list</ulink>, privoxy-announce@lists.privoxy.org.
479 In order not to lose your personal changes and adjustments when updating
480 to the latest <literal>default.action</literal> file we <emphasis>strongly
481 recommend</emphasis> that you use <literal>user.action</literal> and
482 <literal>user.filter</literal> for your local
483 customizations of <application>Privoxy</application>. See the <link
484 linkend="actions-file">Chapter on actions files</link> for details.
492 <!-- ~ End section ~ -->
494 <!-- ~~~~~ New section ~~~~~ -->
495 <sect1 id="whatsnew">
496 <title>What's New in this Release</title>
500 <!-- ~~~~~ New section ~~~~~ -->
502 <sect2 id="upgradersnote">
503 <title>Note to Upgraders</title>
506 A quick list of things to be aware of before upgrading from earlier
507 versions of <application>Privoxy</application>:
514 The recommended way to upgrade &my-app; is to backup your old
515 configuration files, install the new ones, verify that &my-app;
516 is working correctly and finally merge back your changes using
517 <application>diff</application> and maybe <application>patch</application>.
520 There are a number of new features in each &my-app; release and
521 most of them have to be explicitly enabled in the configuration
522 files. Old configuration files obviously don't do that and due
523 to syntax changes using old configuration files with a new
524 &my-app; isn't always possible anyway.
529 Note that some installers remove earlier versions completely,
530 including configuration files, therefore you should really save
531 any important configuration files!
536 On the other hand, other installers don't overwrite existing configuration
537 files, thinking you will want to do that yourself.
542 In the default configuration only fatal errors are logged now.
543 You can change that in the <link linkend="DEBUG">debug section</link>
544 of the configuration file. You may also want to enable more verbose
545 logging until you verified that the new &my-app; version is working
552 Three other config file settings are now off by default:
553 <link linkend="enable-remote-toggle">enable-remote-toggle</link>,
554 <link linkend="enable-remote-http-toggle">enable-remote-http-toggle</link>,
555 and <link linkend="enable-edit-actions">enable-edit-actions</link>.
556 If you use or want these, you will need to explicitly enable them, and
557 be aware of the security issues involved.
564 What constitutes a <quote>default</quote> configuration has changed,
565 and you may want to review which actions are <quote>on</quote> by
566 default. This is primarily a matter of emphasis, but some features
567 you may have been used to, may now be <quote>off</quote> by default.
568 There are also a number of new actions and filters you may want to
569 consider, most of which are not fully incorporated into the default
570 settings as yet (see above).
577 The default actions setting is now <literal>Cautious</literal>. Previous
578 releases had a default setting of <literal>Medium</literal>. Experienced
579 users may want to adjust this, as it is fairly conservative by &my-app;
580 standards and past practices. See <ulink
581 url="http://config.privoxy.org/edit-actions-list?f=default">
582 http://config.privoxy.org/edit-actions-list?f=default</ulink>. New users
583 should try the default settings for a while before turning up the volume.
589 The default setting has filtering turned <emphasis>off</emphasis>, which
590 subsequently means that compression is <emphasis>on</emphasis>. Remember
591 that filtering does not work on compressed pages, so if you use, or want to
592 use, filtering, you will need to force compression off. Example:
595 { +<link linkend="filter">filter</link>{google} +<link linkend="prevent-compression">prevent-compression</link> }
598 Or if you use a number of filters, or filter many sites, you may just want
599 to turn off compression for all sites in
600 <filename>default.action</filename> (or
601 <filename>user.action</filename>).
608 Also, <link linkend="SESSION-COOKIES-ONLY">session-cookies-only</link> is
609 off by default now. If you've liked this feature in the past, you may want
610 to turn it back on in <filename>user.action</filename> now.
617 Some installers may not automatically start
618 <application>Privoxy</application> after installation.
628 <!-- ~~~~~ New section ~~~~~ -->
629 <sect1 id="quickstart"><title>Quickstart to Using Privoxy</title>
635 Install <application>Privoxy</application>. See the <link
636 linkend="installation">Installation Section</link> below for platform specific
643 Advanced users and those who want to offer <application>Privoxy</application>
644 service to more than just their local machine should check the <link
645 linkend="config">main config file</link>, especially the <link
646 linkend="access-control">security-relevant</link> options. These are
653 Start <application>Privoxy</application>, if the installation program has
654 not done this already (may vary according to platform). See the section
655 <link linkend="startup">Starting <application>Privoxy</application></link>.
661 Set your browser to use <application>Privoxy</application> as HTTP and
662 HTTPS (SSL) <ulink url="https://en.wikipedia.org/wiki/Proxy_server">proxy</ulink>
663 by setting the proxy configuration for address of
664 <literal>127.0.0.1</literal> and port <literal>8118</literal>.
665 <emphasis>DO NOT</emphasis> activate proxying for <literal>FTP</literal> or
666 any protocols besides HTTP and HTTPS (SSL) unless you intend to prevent your
667 browser from using these protocols.
673 Flush your browser's disk and memory caches, to remove any cached ad images.
674 If using <application>Privoxy</application> to manage
675 <ulink url="https://en.wikipedia.org/wiki/Browser_cookie">cookies</ulink>,
676 you should remove any currently stored cookies too.
682 A default installation should provide a reasonable starting point for
683 most. There will undoubtedly be occasions where you will want to adjust the
684 configuration, but that can be dealt with as the need arises. Little
685 to no initial configuration is required in most cases, you may want
687 <ulink url="config.html#ENABLE-EDIT-ACTIONS">web-based action editor</ulink> though.
688 Be sure to read the warnings first.
691 See the <link linkend="configuration">Configuration section</link> for more
692 configuration options, and how to customize your installation.
693 You might also want to look at the <link
694 linkend="quickstart-ad-blocking">next section</link> for a quick
695 introduction to how <application>Privoxy</application> blocks ads and
702 If you experience ads that slip through, innocent images that are
703 blocked, or otherwise feel the need to fine-tune
704 <application>Privoxy's</application> behavior, take a look at the <link
705 linkend="actions-file">actions files</link>. As a quick start, you might
706 find the <link linkend="act-examples">richly commented examples</link>
707 helpful. You can also view and edit the actions files through the <ulink
708 url="http://config.privoxy.org">web-based user interface</ulink>. The
709 Appendix <quote><link linkend="actionsanat">Troubleshooting: Anatomy of an
710 Action</link></quote> has hints on how to understand and debug actions that
711 <quote>misbehave</quote>.
717 Please see the section <link linkend="contact">Contacting the
718 Developers</link> on how to report bugs, problems with websites or to get
725 Now enjoy surfing with enhanced control, comfort and privacy!
732 <!-- ~~~~~ New section ~~~~~ -->
734 <sect2 id="quickstart-ad-blocking">
735 <title>Quickstart to Ad Blocking</title>
737 NOTE: This section is deliberately redundant for those that don't
738 want to read the whole thing (which is getting lengthy).
741 Ad blocking is but one of <application>Privoxy's</application>
742 array of features. Many of these features are for the technically minded advanced
743 user. But, ad and banner blocking is surely common ground for everybody.
746 This section will provide a quick summary of ad blocking so
747 you can get up to speed quickly without having to read the more extensive
748 information provided below, though this is highly recommended.
751 First a bit of a warning ... blocking ads is much like blocking SPAM: the
752 more aggressive you are about it, the more likely you are to block
753 things that were not intended. And the more likely that some things
754 may not work as intended. So there is a trade off here. If you want
755 extreme ad free browsing, be prepared to deal with more
756 <quote>problem</quote> sites, and to spend more time adjusting the
757 configuration to solve these unintended consequences. In short, there is
758 not an easy way to eliminate <emphasis>all</emphasis> ads. Either take
759 the easy way and settle for <emphasis>most</emphasis> ads blocked with the
760 default configuration, or jump in and tweak it for your personal surfing
761 habits and preferences.
764 Secondly, a brief explanation of <application>Privoxy's </application>
765 <quote>actions</quote>. <quote>Actions</quote> in this context, are
766 the directives we use to tell <application>Privoxy</application> to perform
767 some task relating to HTTP transactions (i.e. web browsing). We tell
768 <application>Privoxy</application> to take some <quote>action</quote>. Each
769 action has a unique name and function. While there are many potential
770 <application>actions</application> in <application>Privoxy's</application>
771 arsenal, only a few are used for ad blocking. <link
772 linkend="actions">Actions</link>, and <link linkend="actions-file">action
773 configuration files</link>, are explained in depth below.
776 Actions are specified in <application>Privoxy's</application> configuration,
777 followed by one or more URLs to which the action should apply. URLs
778 can actually be URL type <link linkend="af-patterns">patterns</link> that use
779 wildcards so they can apply potentially to a range of similar URLs. The
780 actions, together with the URL patterns are called a section.
783 When you connect to a website, the full URL will either match one or more
784 of the sections as defined in <application>Privoxy's</application> configuration,
785 or not. If so, then <application>Privoxy</application> will perform the
786 respective actions. If not, then nothing special happens. Furthermore, web
787 pages may contain embedded, secondary URLs that your web browser will
788 use to load additional components of the page, as it parses the
789 original page's HTML content. An ad image for instance, is just an URL
790 embedded in the page somewhere. The image itself may be on the same server,
791 or a server somewhere else on the Internet. Complex web pages will have many
792 such embedded URLs. &my-app; can deal with each URL individually, so, for
793 instance, the main page text is not touched, but images from such-and-such
798 The most important actions for basic ad blocking are: <literal><link
799 linkend="block">block</link></literal>, <literal><link
800 linkend="handle-as-image">handle-as-image</link></literal>,
802 linkend="handle-as-empty-document">handle-as-empty-document</link></literal>,and
803 <literal><link linkend="set-image-blocker">set-image-blocker</link></literal>:
810 <literal><link linkend="block">block</link></literal> - this is perhaps
811 the single most used action, and is particularly important for ad blocking.
812 This action stops any contact between your browser and any URL patterns
813 that match this action's configuration. It can be used for blocking ads,
814 but also anything that is determined to be unwanted. By itself, it simply
815 stops any communication with the remote server and sends
816 <application>Privoxy</application>'s own built-in BLOCKED page instead to
817 let you now what has happened (with some exceptions, see below).
823 <literal><link linkend="handle-as-image">handle-as-image</link></literal> -
824 tells <application>Privoxy</application> to treat this URL as an image.
825 <application>Privoxy</application>'s default configuration already does this
826 for all common image types (e.g. GIF), but there are many situations where this
827 is not so easy to determine. So we'll force it in these cases. This is particularly
828 important for ad blocking, since only if we know that it's an image of
829 some kind, can we replace it with an image of our choosing, instead of the
830 <application>Privoxy</application> BLOCKED page (which would only result in
831 a <quote>broken image</quote> icon). There are some limitations to this
832 though. For instance, you can't just brute-force an image substitution for
833 an entire HTML page in most situations.
839 <literal><link linkend="handle-as-empty-document">handle-as-empty-document</link></literal> -
840 sends an empty document instead of <application>Privoxy's</application>
841 normal BLOCKED HTML page. This is useful for file types that are neither
842 HTML nor images, such as blocking JavaScript files.
849 linkend="set-image-blocker">set-image-blocker</link></literal> - tells
850 <application>Privoxy</application> what to display in place of an ad image that
851 has hit a block rule. For this to come into play, the URL must match a
852 <literal><link linkend="block">block</link></literal> action somewhere in the
853 configuration, <emphasis>and</emphasis>, it must also match an
854 <literal><link linkend="handle-as-image">handle-as-image</link></literal> action.
857 The configuration options on what to display instead of the ad are:
861 <emphasis>pattern</emphasis> - a checkerboard pattern, so that an ad
862 replacement is obvious. This is the default.
867 <emphasis>blank</emphasis> - A very small empty GIF image is displayed.
868 This is the so-called <quote>invisible</quote> configuration option.
873 <emphasis>http://<URL></emphasis> - A redirect to any image anywhere
874 of the user's choosing (advanced usage).
882 Advanced users will eventually want to explore &my-app;
883 <literal><link linkend="filter">filters</link></literal> as well. Filters
884 are very different from <literal><link
885 linkend="block">blocks</link></literal>.
886 A <quote>block</quote> blocks a site, page, or unwanted contented. Filters
887 are a way of filtering or modifying what is actually on the page. An example
888 filter usage: a text replacement of <quote>no-no</quote> for
889 <quote>nasty-word</quote>. That is a very simple example. This process can be
890 used for ad blocking, but it is more in the realm of advanced usage and has
891 some pitfalls to be wary off.
895 The quickest way to adjust any of these settings is with your browser through
896 the special <application>Privoxy</application> editor at <ulink
897 url="http://config.privoxy.org/show-status">http://config.privoxy.org/show-status</ulink>
898 (shortcut: <ulink url="http://p.p/">http://p.p/show-status</ulink>). This
899 is an internal page, and does not require Internet access.
903 Note that as of <application>Privoxy</application> 3.0.7 beta the
904 action editor is disabled by default. Check the
905 <ulink url="config.html#ENABLE-EDIT-ACTIONS">enable-edit-actions
906 section in the configuration file</ulink> to learn why and in which
907 cases it's safe to enable again.
911 If you decided to enable the action editor, select the appropriate
912 <quote>actions</quote> file, and click
913 <quote><guibutton>Edit</guibutton></quote>. It is best to put personal or
914 local preferences in <filename>user.action</filename> since this is not
915 meant to be overwritten during upgrades, and will over-ride the settings in
916 other files. Here you can insert new <quote>actions</quote>, and URLs for ad
917 blocking or other purposes, and make other adjustments to the configuration.
918 <application>Privoxy</application> will detect these changes automatically.
922 A quick and simple step by step example:
929 Right click on the ad image to be blocked, then select
930 <quote><guimenuitem>Copy Link Location</guimenuitem></quote> from the
938 url="http://config.privoxy.org/show-status">http://config.privoxy.org/show-status</ulink>
943 Find <filename>user.action</filename> in the top section, and click
944 on <quote><guibutton>Edit</guibutton></quote>:
947 <!-- image of editor and actions files selections -->
948 <figure pgwide="0" float="0"><title>Actions Files in Use</title>
951 <imagedata fileref="files-in-use.jpg" format="jpg">
954 <phrase>[ Screenshot of Actions Files in Use ]</phrase>
962 You should have a section with only
963 <literal><link linkend="block">block</link></literal> listed under
964 <quote>Actions:</quote>.
965 If not, click a <quote><guibutton>Insert new section below</guibutton></quote>
966 button, and in the new section that just appeared, click the
967 <guibutton>Edit</guibutton> button right under the word <quote>Actions:</quote>.
968 This will bring up a list of all actions. Find
969 <literal><link linkend="block">block</link></literal> near the top, and click
970 in the <quote>Enabled</quote> column, then <quote><guibutton>Submit</guibutton></quote>
976 Now, in the <literal><link linkend="block">block</link></literal> actions section,
977 click the <quote><guibutton>Add</guibutton></quote> button, and paste the URL the
978 browser got from <quote><guimenuitem>Copy Link Location</guimenuitem></quote>.
979 Remove the <literal>http://</literal> at the beginning of the URL. Then, click
980 <quote><guibutton>Submit</guibutton></quote> (or
981 <quote><guibutton>OK</guibutton></quote> if in a pop-up window).
986 Now go back to the original page, and press <keycap>SHIFT-Reload</keycap>
987 (or flush all browser caches). The image should be gone now.
994 This is a very crude and simple example. There might be good reasons to use a
995 wildcard pattern match to include potentially similar images from the same
996 site. For a more extensive explanation of <quote>patterns</quote>, and
997 the entire actions concept, see <link linkend="actions-file">the Actions
1002 For advanced users who want to hand edit their config files, you might want
1003 to now go to the <link linkend="act-examples">Actions Files Tutorial</link>.
1004 The ideas explained therein also apply to the web-based editor.
1007 There are also various
1008 <link linkend="filter">filters</link> that can be used for ad blocking
1009 (filters are a special subset of actions). These
1010 fall into the <quote>advanced</quote> usage category, and are explained in
1011 depth in later sections.
1018 <!-- ~ End section ~ -->
1021 <!-- ~~~~~ New section ~~~~~ -->
1022 <sect1 id="startup">
1023 <title>Starting Privoxy</title>
1025 Before launching <application>Privoxy</application> for the first time, you
1026 will want to configure your browser(s) to use
1027 <application>Privoxy</application> as a HTTP and HTTPS (SSL)
1028 <ulink url="https://en.wikipedia.org/wiki/Proxy_server">proxy</ulink>. The default is
1029 127.0.0.1 (or localhost) for the proxy address, and port 8118 (earlier versions
1030 used port 8000). This is the one configuration step <emphasis>that must be done
1034 Please note that <application>Privoxy</application> can only proxy HTTP and
1035 HTTPS traffic. It will not work with FTP or other protocols.
1038 <!-- image of Mozilla Proxy configuration -->
1039 <figure pgwide="0" float="0"><title>Proxy Configuration Showing
1040 Mozilla Firefox HTTP and HTTPS (SSL) Settings</title>
1043 <imagedata fileref="proxy_setup.jpg" format="jpg">
1046 <phrase>[ Screenshot of Mozilla Firefox Proxy Configuration ]</phrase>
1053 With <application>Firefox</application>, this is typically set under:
1057 <guibutton>Edit</guibutton> -> <guibutton>Preferences</guibutton> -> <guibutton>Network Settings</guibutton> -> <guibutton>Settings</guibutton>
1061 Or optionally on some platforms:
1065 <guibutton>Edit</guibutton> -> <guibutton>Preferences</guibutton> -> <guibutton>General</guibutton> -> <guibutton>Connection Settings</guibutton> -> <guibutton>Manual Proxy Configuration</guibutton>
1070 With <application>Netscape</application> (and
1071 <application>Mozilla</application>), this can be set under:
1076 <!-- Mix ascii and gui art, something for everybody -->
1077 <!-- spacing on this is tricky -->
1078 <guibutton>Edit</guibutton> -> <guibutton>Preferences</guibutton> -> <guibutton>Advanced</guibutton> -> <guibutton>Proxies</guibutton> -> <guibutton>HTTP Proxy</guibutton>
1082 For <application>Internet Explorer v.5-7</application>:
1086 <guibutton>Tools</guibutton> -> <guibutton>Internet Options</guibutton> -> <guibutton>Connections</guibutton> -> <guibutton>LAN Settings</guibutton>
1090 Then, check <quote>Use Proxy</quote> and fill in the appropriate info
1091 (Address: 127.0.0.1, Port: 8118). Include HTTPS (SSL), if you want HTTPS
1092 proxy support too (sometimes labeled <quote>Secure</quote>). Make sure any
1093 checkboxes like <quote>Use the same proxy server for all protocols</quote> is
1094 <emphasis>UNCHECKED</emphasis>. You want only HTTP and HTTPS (SSL)!
1097 <!-- image of IE Proxy configuration -->
1098 <figure pgwide="0" float="0"><title>Proxy Configuration Showing
1099 Internet Explorer HTTP and HTTPS (Secure) Settings</title>
1102 <imagedata fileref="proxy2.jpg" format="jpg">
1105 <phrase>[ Screenshot of IE Proxy Configuration ]</phrase>
1112 After doing this, flush your browser's disk and memory caches to force a
1113 re-reading of all pages and to get rid of any ads that may be cached. Remove
1114 any <ulink url="https://en.wikipedia.org/wiki/Browser_cookie">cookies</ulink>,
1115 if you want <application>Privoxy</application> to manage that. You are now
1116 ready to start enjoying the benefits of using
1117 <application>Privoxy</application>!
1121 <application>Privoxy</application> itself is typically started by specifying the
1122 main configuration file to be used on the command line. If no configuration
1123 file is specified on the command line, <application>Privoxy</application>
1124 will look for a file named <filename>config</filename> in the current
1125 directory. Except on Win32 where it will try <filename>config.txt</filename>.
1128 <sect2 id="start-debian">
1129 <title>Debian</title>
1131 We use a script. Note that Debian typically starts &my-app; upon booting per
1132 default. It will use the file
1133 <filename>/etc/privoxy/config</filename> as its main configuration
1137 # /etc/init.d/privoxy start
1141 <sect2 id="start-freebsd">
1142 <title>FreeBSD and ElectroBSD</title>
1144 To start <application>Privoxy</application> upon booting, add
1145 "privoxy_enable='YES'" to <filename>/etc/rc.conf</filename>.
1146 <application>Privoxy</application> will use
1147 <filename>/usr/local/etc/privoxy/config</filename> as its main
1151 If you installed <application>Privoxy</application> into a jail, the
1152 paths above are relative to the jail root.
1155 To start <application>Privoxy</application> manually, run:
1158 # service privoxy onestart
1162 <sect2 id="start-windows">
1163 <title>Windows</title>
1165 Click on the &my-app; Icon to start <application>Privoxy</application>. If no configuration file is
1166 specified on the command line, <application>Privoxy</application> will look
1167 for a file named <filename>config.txt</filename>. Note that Windows will
1168 automatically start &my-app; when the system starts if you chose that option
1172 <application>Privoxy</application> can run with full Windows service functionality.
1173 On Windows only, the &my-app; program has two new command line arguments
1174 to install and uninstall &my-app; as a service. See the
1175 <link linkend="installation-pack-win">Windows Installation
1176 instructions</link> for details.
1180 <sect2 id="start-unices">
1181 <title>Generic instructions for Unix derivates (Solaris, NetBSD, HP-UX etc.)</title>
1183 Example Unix startup command:
1186 # /usr/sbin/privoxy --user privoxy /etc/privoxy/config
1189 Note that if you installed <application>Privoxy</application> through
1190 a package manager, the package will probably contain a platform-specific
1191 script or configuration file to start <application>Privoxy</application>
1196 <sect2 id="start-macosx">
1197 <title>Mac OS X</title>
1199 The privoxy service will automatically start after a successful installation
1200 (and thereafter every time your computer starts up) however you will need to
1201 configure your web browser(s) to use it. To do so, configure them to use a
1202 proxy for HTTP and HTTPS at the address 127.0.0.1:8118.
1205 To prevent the privoxy service from automatically starting when your computer
1206 starts up, remove or rename the file <literal>/Library/LaunchDaemons/org.ijbswa.privoxy.plist</literal>
1207 (on OS X 10.5 and higher) or the folder named
1208 <literal>/Library/StartupItems/Privoxy</literal> (on OS X 10.4 'Tiger').
1211 To manually start or stop the privoxy service, use the scripts startPrivoxy.sh
1212 and stopPrivoxy.sh supplied in /Applications/Privoxy. They must be run from an
1213 administrator account, using sudo.
1221 See the section <link linkend="cmdoptions">Command line options</link> for
1225 must find a better place for this paragraph
1228 The included default configuration files should give a reasonable starting
1229 point. Most of the per site configuration is done in the
1230 <ulink url="actions-file.html"><quote>actions</quote></ulink> files. These are
1231 where various cookie actions are defined, ad and banner blocking, and other
1232 aspects of <application>Privoxy</application> configuration. There are several
1233 such files included, with varying levels of aggressiveness.
1237 You will probably want to keep an eye out for sites for which you may prefer
1238 persistent cookies, and add these to your actions configuration as needed. By
1239 default, most of these will be accepted only during the current browser
1240 session (aka <quote>session cookies</quote>), unless you add them to the
1241 configuration. If you want the browser to handle this instead, you will need
1242 to edit <filename>user.action</filename> (or through the web based interface)
1243 and disable this feature. If you use more than one browser, it would make
1244 more sense to let <application>Privoxy</application> handle this. In which
1245 case, the browser(s) should be set to accept all cookies.
1249 Another feature where you will probably want to define exceptions for trusted
1250 sites is the popup-killing (through <ulink
1251 url="actions-file.html#FILTER-POPUPS"><quote>+filter{popups}</quote></ulink>),
1252 because your favorite shopping, banking, or leisure site may need
1253 popups (explained below).
1257 <application>Privoxy</application> does not support all of the optional HTTP/1.1
1258 features yet. In the unlikely event that you experience inexplicable problems
1259 with browsers that use HTTP/1.1 per default
1260 (like <application>Mozilla</application> or recent versions of I.E.), you might
1261 try to force HTTP/1.0 compatibility. For Mozilla, look under <literal>Edit ->
1262 Preferences -> Debug -> Networking</literal>.
1263 Alternatively, set the <quote>+downgrade-http-version</quote> config option in
1264 <filename>default.action</filename> which will downgrade your browser's HTTP
1265 requests from HTTP/1.1 to HTTP/1.0 before processing them.
1269 After running <application>Privoxy</application> for a while, you can
1270 start to fine tune the configuration to suit your personal, or site,
1271 preferences and requirements. There are many, many aspects that can
1272 be customized. <quote>Actions</quote>
1273 can be adjusted by pointing your browser to
1274 <ulink url="http://config.privoxy.org/">http://config.privoxy.org/</ulink>
1275 (shortcut: <ulink url="http://p.p/">http://p.p/</ulink>),
1276 and then follow the link to <quote>View & Change the Current Configuration</quote>.
1277 (This is an internal page and does not require Internet access.)
1281 In fact, various aspects of <application>Privoxy</application>
1282 configuration can be viewed from this page, including
1283 current configuration parameters, source code version numbers,
1284 the browser's request headers, and <quote>actions</quote> that apply
1285 to a given URL. In addition to the actions file
1286 editor mentioned above, <application>Privoxy</application> can also
1287 be turned <quote>on</quote> and <quote>off</quote> (toggled) from this page.
1291 If you encounter problems, try loading the page without
1292 <application>Privoxy</application>. If that helps, enter the URL where
1293 you have the problems into <ulink url="http://p.p/show-url-info">the browser
1294 based rule tracing utility</ulink>. See which rules apply and why, and
1295 then try turning them off for that site one after the other, until the problem
1296 is gone. When you have found the culprit, you might want to turn the rest on
1301 If the above paragraph sounds gibberish to you, you might want to <link
1302 linkend="actions-file">read more about the actions concept</link>
1303 or even dive deep into the <link linkend="actionsanat">Appendix
1308 If you can't get rid of the problem at all, think you've found a bug in
1309 Privoxy, want to propose a new feature or smarter rules, please see the
1310 section <link linkend="contact"><quote>Contacting the
1311 Developers</quote></link> below.
1316 <!-- ~~~~~ New section ~~~~~ -->
1317 <sect2 id="cmdoptions">
1318 <title>Command Line Options</title>
1320 <application>Privoxy</application> may be invoked with the following
1321 command-line options:
1328 <emphasis>--config-test</emphasis>
1331 Exit after loading the configuration files before binding to
1332 the listen address. The exit code signals whether or not the
1333 configuration files have been successfully loaded.
1336 If the exit code is 1, at least one of the configuration files
1337 is invalid, if it is 0, all the configuration files have been
1338 successfully loaded (but may still contain errors that can
1339 currently only be detected at run time).
1342 This option doesn't affect the log setting, combination with
1343 <emphasis>--no-daemon</emphasis> is recommended if a configured
1344 log file shouldn't be used.
1349 <emphasis>--version</emphasis>
1352 Print version info and exit. Unix only.
1357 <emphasis>--help</emphasis>
1360 Print short usage info and exit. Unix only.
1365 <emphasis>--no-daemon</emphasis>
1368 Don't become a daemon, i.e. don't fork and become process group
1369 leader, and don't detach from controlling tty. Unix only.
1374 <emphasis>--pidfile FILE</emphasis>
1377 On startup, write the process ID to <emphasis>FILE</emphasis>. Delete the
1378 <emphasis>FILE</emphasis> on exit. Failure to create or delete the
1379 <emphasis>FILE</emphasis> is non-fatal. If no <emphasis>FILE</emphasis>
1380 option is given, no PID file will be used. Unix only.
1385 <emphasis>--user USER[.GROUP]</emphasis>
1388 After (optionally) writing the PID file, assume the user ID of
1389 <emphasis>USER</emphasis>, and if included the GID of GROUP. Exit if the
1390 privileges are not sufficient to do so. Unix only.
1395 <emphasis>--chroot</emphasis>
1398 Before changing to the user ID given in the <emphasis>--user</emphasis> option,
1399 chroot to that user's home directory, i.e. make the kernel pretend to the &my-app;
1400 process that the directory tree starts there. If set up carefully, this can limit
1401 the impact of possible vulnerabilities in &my-app; to the files contained in that hierarchy.
1407 <emphasis>--pre-chroot-nslookup hostname</emphasis>
1410 Specifies a hostname (for example www.privoxy.org) to look up before doing a chroot.
1411 On some systems, initializing the resolver library involves reading config files from
1412 /etc and/or loading additional shared libraries from /lib.
1413 On these systems, doing a hostname lookup before the chroot reduces
1414 the number of files that must be copied into the chroot tree.
1417 For fastest startup speed, a good value is a hostname that is not in /etc/hosts but that
1418 your local name server (listed in /etc/resolv.conf) can resolve without recursion
1419 (that is, without having to ask any other name servers). The hostname need not exist,
1420 but if it doesn't, an error message (which can be ignored) will be output.
1426 <emphasis>configfile</emphasis>
1429 If no <emphasis>configfile</emphasis> is included on the command line,
1430 <application>Privoxy</application> will look for a file named
1431 <quote>config</quote> in the current directory (except on Win32
1432 where it will look for <quote>config.txt</quote> instead). Specify
1433 full path to avoid confusion. If no config file is found,
1434 <application>Privoxy</application> will fail to start.
1441 On <application>MS Windows</application> only there are two additional
1442 command-line options to allow <application>Privoxy</application> to install and
1443 run as a <emphasis>service</emphasis>. See the
1444 <link linkend="installation-pack-win">Window Installation section</link>
1452 <!-- ~ End section ~ -->
1455 <!-- ~~~~~ New section ~~~~~ -->
1456 <sect1 id="configuration"><title>Privoxy Configuration</title>
1458 All <application>Privoxy</application> configuration is stored
1459 in text files. These files can be edited with a text editor.
1460 Many important aspects of <application>Privoxy</application> can
1461 also be controlled easily with a web browser.
1465 <!-- ~~~~~ New section ~~~~~ -->
1467 <sect2 id="control-with-webbrowser">
1468 <title>Controlling Privoxy with Your Web Browser</title>
1470 <application>Privoxy</application>'s user interface can be reached through the special
1471 URL <ulink url="http://config.privoxy.org/">http://config.privoxy.org/</ulink>
1472 (shortcut: <ulink url="http://p.p/">http://p.p/</ulink>),
1473 which is a built-in page and works without Internet access.
1474 You will see the following section:
1477 <!-- Needs to be put in a table and colorized -->
1478 <screen><!-- want the background color that goes with screen -->
1480 <bridgehead renderas="sect2"> Privoxy Menu</bridgehead>
1483 ▪ <ulink url="http://config.privoxy.org/show-status">View & change the current configuration</ulink>
1486 ▪ <ulink url="http://config.privoxy.org/client-tags">View or toggle the tags that can be set based on the client's address</ulink>
1489 ▪ <ulink url="http://config.privoxy.org/show-request">View the request headers.</ulink>
1492 ▪ <ulink url="http://config.privoxy.org/show-url-info">Look up which actions apply to a URL and why</ulink>
1495 ▪ <ulink url="http://config.privoxy.org/toggle">Toggle Privoxy on or off</ulink>
1498 ▪ <ulink
1499 url="https://www.privoxy.org/&p-version;/user-manual/">Documentation</ulink>
1507 This should be self-explanatory. Note the first item leads to an editor for the
1508 <link linkend="actions-file">actions files</link>, which is where the ad, banner,
1509 cookie, and URL blocking magic is configured as well as other advanced features of
1510 <application>Privoxy</application>. This is an easy way to adjust various
1511 aspects of <application>Privoxy</application> configuration. The actions
1512 file, and other configuration files, are explained in detail below.
1516 <quote>Toggle Privoxy On or Off</quote> is handy for sites that might
1517 have problems with your current actions and filters. You can in fact use
1518 it as a test to see whether it is <application>Privoxy</application>
1519 causing the problem or not. <application>Privoxy</application> continues
1520 to run as a proxy in this case, but all manipulation is disabled, i.e.
1521 <application>Privoxy</application> acts like a normal forwarding proxy.
1525 Note that several of the features described above are disabled by default
1526 in <application>Privoxy</application> 3.0.7 beta and later.
1528 <ulink url="config.html">configuration file</ulink> to learn why
1529 and in which cases it's safe to enable them again.
1534 <!-- ~ End section ~ -->
1539 <!-- ~~~~~ New section ~~~~~ -->
1541 <sect2 id="confoverview">
1542 <title>Configuration Files Overview</title>
1544 For Unix, *BSD and GNU/Linux, all configuration files are located in
1545 <filename>/etc/privoxy/</filename> by default. For MS Windows
1546 these are all in the same directory as the
1547 <application>Privoxy</application> executable. <![%p-not-stable;[ The name
1548 and number of configuration files has changed from previous versions, and is
1549 subject to change as development progresses.]]>
1553 The installed defaults provide a reasonable starting point, though
1554 some settings may be aggressive by some standards. For the time being, the
1555 principle configuration files are:
1562 The <link linkend="config">main configuration file</link> is named <filename>config</filename>
1563 on GNU/Linux, Unix, BSD, and <filename>config.txt</filename>
1564 on Windows. This is a required file.
1570 <filename>match-all.action</filename> is used to define which <quote>actions</quote>
1571 relating to banner-blocking, images, pop-ups, content modification, cookie handling
1572 etc should be applied by default. It should be the first actions file loaded.
1575 <filename>default.action</filename> defines many exceptions (both positive and negative)
1576 from the default set of actions that's configured in <filename>match-all.action</filename>.
1577 It should be the second actions file loaded and shouldn't be edited by the user.
1580 Multiple actions files may be defined in <filename>config</filename>. These
1581 are processed in the order they are defined. Local customizations and locally
1582 preferred exceptions to the default policies as defined in
1583 <filename>match-all.action</filename> (which you will most probably want
1584 to define sooner or later) are best applied in <filename>user.action</filename>,
1585 where you can preserve them across upgrades. The file isn't installed by all
1586 installers, but you can easily create it yourself with a text editor.
1589 There is also a web based editor that can be accessed from
1591 url="http://config.privoxy.org/show-status">http://config.privoxy.org/show-status</ulink>
1593 url="http://p.p/show-status">http://p.p/show-status</ulink>) for the
1594 various actions files.
1600 <quote>Filter files</quote> (the <link linkend="filter-file">filter
1601 file</link>) can be used to re-write the raw page content, including
1602 viewable text as well as embedded HTML and JavaScript, and whatever else
1603 lurks on any given web page. The filtering jobs are only pre-defined here;
1604 whether to apply them or not is up to the actions files.
1605 <filename>default.filter</filename> includes various filters made
1606 available for use by the developers. Some are much more intrusive than
1607 others, and all should be used with caution. You may define additional
1608 filter files in <filename>config</filename> as you can with
1609 actions files. We suggest <filename>user.filter</filename> for any
1610 locally defined filters or customizations.
1617 The syntax of the configuration and filter files may change between different
1618 Privoxy versions, unfortunately some enhancements cost backwards compatibility.
1619 <!-- Add link to documentation-->
1623 All files use the <quote><literal>#</literal></quote> character to denote a
1624 comment (the rest of the line will be ignored) and understand line continuation
1625 through placing a backslash ("<literal>\</literal>") as the very last character
1626 in a line. If the <literal>#</literal> is preceded by a backslash, it looses
1627 its special function. Placing a <literal>#</literal> in front of an otherwise
1628 valid configuration line to prevent it from being interpreted is called "commenting
1629 out" that line. Blank lines are ignored.
1633 The actions files and filter files
1634 can use Perl style <link linkend="regex">regular expressions</link> for
1635 maximum flexibility.
1639 After making any changes, there is no need to restart
1640 <application>Privoxy</application> in order for the changes to take
1641 effect. <application>Privoxy</application> detects such changes
1642 automatically. Note, however, that it may take one or two additional
1643 requests for the change to take effect. When changing the listening address
1644 of <application>Privoxy</application>, these <quote>wake up</quote> requests
1645 must obviously be sent to the <emphasis>old</emphasis> listening address.
1650 While under development, the configuration content is subject to change.
1651 The below documentation may not be accurate by the time you read this.
1652 Also, what constitutes a <quote>default</quote> setting, may change, so
1653 please check all your configuration files on important issues.
1659 <!-- ~ End section ~ -->
1662 <!-- ~~~~~~~~ New section Header ~~~~~~~~~ -->
1664 <!-- **************************************************** -->
1665 <!-- Include config.sgml here -->
1666 <!-- This is where the entire config file is detailed. -->
1668 <!-- end include -->
1671 <!-- ~ End section ~ -->
1675 <!-- ~~~~~~~~ New section Header ~~~~~~~~~ -->
1677 <sect1 id="actions-file"><title>Actions Files</title>
1681 XXX: similar descriptions are in the Configuration Files sections.
1682 We should only describe them at one place.
1685 The actions files are used to define what <emphasis>actions</emphasis>
1686 <application>Privoxy</application> takes for which URLs, and thus determines
1687 how ad images, cookies and various other aspects of HTTP content and
1688 transactions are handled, and on which sites (or even parts thereof).
1689 There are a number of such actions, with a wide range of functionality.
1690 Each action does something a little different.
1691 These actions give us a veritable arsenal of tools with which to exert
1692 our control, preferences and independence. Actions can be combined so that
1693 their effects are aggregated when applied against a given set of URLs.
1697 are three action files included with <application>Privoxy</application> with
1703 <filename>match-all.action</filename> - is used to define which
1704 <quote>actions</quote> relating to banner-blocking, images, pop-ups,
1705 content modification, cookie handling etc should be applied by default.
1706 It should be the first actions file loaded
1711 <filename>default.action</filename> - defines many exceptions (both
1712 positive and negative) from the default set of actions that's configured
1713 in <filename>match-all.action</filename>. It is a set of rules that should
1714 work reasonably well as-is for most users. This file is only supposed to
1715 be edited by the developers. It should be the second actions file loaded.
1720 <filename>user.action</filename> - is intended to be for local site
1721 preferences and exceptions. As an example, if your ISP or your bank
1722 has specific requirements, and need special handling, this kind of
1723 thing should go here. This file will not be upgraded.
1728 <guibutton>Edit</guibutton> <guibutton>Set to Cautious</guibutton> <guibutton>Set to Medium</guibutton> <guibutton>Set to Advanced</guibutton>
1731 These have increasing levels of aggressiveness <emphasis>and have no
1732 influence on your browsing unless you select them explicitly in the
1733 editor</emphasis>. A default installation should be pre-set to
1734 <literal>Cautious</literal>. New users should try this for a while before
1735 adjusting the settings to more aggressive levels. The more aggressive
1736 the settings, then the more likelihood there is of problems such as sites
1737 not working as they should.
1740 The <guibutton>Edit</guibutton> button allows you to turn each
1741 action on/off individually for fine-tuning. The <guibutton>Cautious</guibutton>
1742 button changes the actions list to low/safe settings which will activate
1743 ad blocking and a minimal set of &my-app;'s features, and subsequently
1744 there will be less of a chance for accidental problems. The
1745 <guibutton>Medium</guibutton> button sets the list to a medium level of
1746 other features and a low level set of privacy features. The
1747 <guibutton>Advanced</guibutton> button sets the list to a high level of
1748 ad blocking and medium level of privacy. See the chart below. The latter
1749 three buttons over-ride any changes via with the
1750 <guibutton>Edit</guibutton> button. More fine-tuning can be done in the
1751 lower sections of this internal page.
1754 While the actions file editor allows to enable these settings in all
1755 actions files, they are only supposed to be enabled in the first one
1756 to make sure you don't unintentionally overrule earlier rules.
1759 The default profiles, and their associated actions, as pre-defined in
1760 <filename>default.action</filename> are:
1762 <table frame=all id="default-configurations"><title>Default Configurations</title>
1763 <tgroup cols=4 align=left colsep=1 rowsep=1>
1764 <colspec colname=c1>
1765 <colspec colname=c2>
1766 <colspec colname=c3>
1767 <colspec colname=c4>
1770 <entry>Feature</entry>
1771 <entry>Cautious</entry>
1772 <entry>Medium</entry>
1773 <entry>Advanced</entry>
1778 <!-- <entry>f1</entry> -->
1779 <!-- <entry>f2</entry> -->
1780 <!-- <entry>f3</entry> -->
1781 <!-- <entry>f4</entry> -->
1787 <entry>Ad-blocking Aggressiveness</entry>
1788 <entry>medium</entry>
1794 <entry>Ad-filtering by size</entry>
1801 <entry>Ad-filtering by link</entry>
1807 <entry>Pop-up killing</entry>
1808 <entry>blocks only</entry>
1809 <entry>blocks only</entry>
1810 <entry>blocks only</entry>
1814 <entry>Privacy Features</entry>
1816 <entry>medium</entry>
1817 <entry>medium/high</entry>
1821 <entry>Cookie handling</entry>
1823 <entry>session-only</entry>
1828 <entry>Referer forging</entry>
1835 <entry>GIF de-animation</entry>
1842 <entry>Fast redirects</entry>
1849 <entry>HTML taming</entry>
1856 <entry>JavaScript taming</entry>
1863 <entry>Web-bug killing</entry>
1870 <entry>Image tag reordering</entry>
1884 The list of actions files to be used are defined in the main configuration
1885 file, and are processed in the order they are defined (e.g.
1886 <filename>default.action</filename> is typically processed before
1887 <filename>user.action</filename>). The content of these can all be viewed and
1889 url="http://config.privoxy.org/show-status">http://config.privoxy.org/show-status</ulink>.
1890 The over-riding principle when applying actions, is that the last action that
1891 matches a given URL wins. The broadest, most general rules go first
1892 (defined in <filename>default.action</filename>),
1893 followed by any exceptions (typically also in
1894 <filename>default.action</filename>), which are then followed lastly by any
1895 local preferences (typically in <emphasis>user</emphasis><filename>.action</filename>).
1896 Generally, <filename>user.action</filename> has the last word.
1900 An actions file typically has multiple sections. If you want to use
1901 <quote>aliases</quote> in an actions file, you have to place the (optional)
1902 <link linkend="aliases">alias section</link> at the top of that file.
1903 Then comes the default set of rules which will apply universally to all
1904 sites and pages (be <emphasis>very careful</emphasis> with using such a
1905 universal set in <filename>user.action</filename> or any other actions file after
1906 <filename>default.action</filename>, because it will override the result
1907 from consulting any previous file). And then below that,
1908 exceptions to the defined universal policies. You can regard
1909 <filename>user.action</filename> as an appendix to <filename>default.action</filename>,
1910 with the advantage that it is a separate file, which makes preserving your
1911 personal settings across <application>Privoxy</application> upgrades easier.
1915 Actions can be used to block anything you want, including ads, banners, or
1916 just some obnoxious URL whose content you would rather not see. Cookies can be accepted
1917 or rejected, or accepted only during the current browser session (i.e. not
1918 written to disk), content can be modified, some JavaScripts tamed, user-tracking
1919 fooled, and much more. See below for a <link linkend="actions">complete list
1923 <!-- ~~~~~ New section ~~~~~ -->
1924 <sect2 id="right-mix">
1925 <title>Finding the Right Mix</title>
1927 Note that some <link linkend="actions">actions</link>, like cookie suppression
1928 or script disabling, may render some sites unusable that rely on these
1929 techniques to work properly. Finding the right mix of actions is not always easy and
1930 certainly a matter of personal taste. And, things can always change, requiring
1931 refinements in the configuration. In general, it can be said that the more
1932 <quote>aggressive</quote> your default settings (in the top section of the
1933 actions file) are, the more exceptions for <quote>trusted</quote> sites you
1934 will have to make later. If, for example, you want to crunch all cookies per
1935 default, you'll have to make exceptions from that rule for sites that you
1936 regularly use and that require cookies for actually useful purposes, like maybe
1937 your bank, favorite shop, or newspaper.
1941 We have tried to provide you with reasonable rules to start from in the
1942 distribution actions files. But there is no general rule of thumb on these
1943 things. There just are too many variables, and sites are constantly changing.
1944 Sooner or later you will want to change the rules (and read this chapter again :).
1948 <!-- ~~~~~ New section ~~~~~ -->
1949 <sect2 id="how-to-edit">
1950 <title>How to Edit</title>
1952 The easiest way to edit the actions files is with a browser by
1953 using our browser-based editor, which can be reached from <ulink
1954 url="http://config.privoxy.org/show-status">http://config.privoxy.org/show-status</ulink>.
1955 Note: the config file option <link
1956 linkend="enable-edit-actions">enable-edit-actions</link> must be enabled for
1957 this to work. The editor allows both fine-grained control over every single
1958 feature on a per-URL basis, and easy choosing from wholesale sets of defaults
1959 like <quote>Cautious</quote>, <quote>Medium</quote> or
1960 <quote>Advanced</quote>. Warning: the <quote>Advanced</quote> setting is more
1961 aggressive, and will be more likely to cause problems for some sites.
1962 Experienced users only!
1966 If you prefer plain text editing to GUIs, you can of course also directly edit the
1967 the actions files with your favorite text editor. Look at
1968 <filename>default.action</filename> which is richly commented with many
1974 <sect2 id="actions-apply">
1975 <title>How Actions are Applied to Requests</title>
1977 Actions files are divided into sections. There are special sections,
1978 like the <quote><link linkend="aliases">alias</link></quote> sections which will
1979 be discussed later. For now let's concentrate on regular sections: They have a
1980 heading line (often split up to multiple lines for readability) which consist
1981 of a list of actions, separated by whitespace and enclosed in curly braces.
1982 Below that, there is a list of URL and tag patterns, each on a separate line.
1986 To determine which actions apply to a request, the URL of the request is
1987 compared to all URL patterns in each <quote>action file</quote>.
1988 Every time it matches, the list of applicable actions for the request is
1989 incrementally updated, using the heading of the section in which the
1990 pattern is located. The same is done again for tags and tag patterns later on.
1994 If multiple applying sections set the same action differently,
1995 the last match wins. If not, the effects are aggregated.
1996 E.g. a URL might match a regular section with a heading line of <literal>{
1997 +<link linkend="handle-as-image">handle-as-image</link> }</literal>,
1998 then later another one with just <literal>{
1999 +<link linkend="block">block</link> }</literal>, resulting
2000 in <emphasis>both</emphasis> actions to apply. And there may well be
2001 cases where you will want to combine actions together. Such a section then
2006 { +<literal>handle-as-image</literal> +<literal>block{Banner ads.}</literal> }
2007 # Block these as if they were images. Send no block page.
2009 media.example.com/.*banners
2010 .example.com/images/ads/</screen>
2013 You can trace this process for URL patterns and any given URL by visiting <ulink
2014 url="http://config.privoxy.org/show-url-info">http://config.privoxy.org/show-url-info</ulink>.
2018 Examples and more detail on this is provided in the Appendix, <link linkend="ACTIONSANAT">
2019 Troubleshooting: Anatomy of an Action</link> section.
2023 <!-- ~~~~~ New section ~~~~~ -->
2024 <sect2 id="af-patterns">
2025 <title>Patterns</title>
2027 As mentioned, <application>Privoxy</application> uses <quote>patterns</quote>
2028 to determine what <emphasis>actions</emphasis> might apply to which sites and
2029 pages your browser attempts to access. These <quote>patterns</quote> use wild
2030 card type <emphasis>pattern</emphasis> matching to achieve a high degree of
2031 flexibility. This allows one expression to be expanded and potentially match
2032 against many similar patterns.
2036 Generally, an URL pattern has the form
2037 <literal><host><port>/<path></literal>, where the
2038 <literal><host></literal>, the <literal><port></literal>
2039 and the <literal><path></literal> are optional. (This is why the special
2040 <literal>/</literal> pattern matches all URLs). Note that the protocol
2041 portion of the URL pattern (e.g. <literal>http://</literal>) should
2042 <emphasis>not</emphasis> be included in the pattern. This is assumed already!
2045 The pattern matching syntax is different for the host and path parts of
2046 the URL. The host part uses a simple globbing type matching technique,
2047 while the path part uses more flexible
2048 <ulink url="https://en.wikipedia.org/wiki/Regular_expressions"><quote>Regular
2049 Expressions</quote></ulink> (POSIX 1003.2).
2052 The port part of a pattern is a decimal port number preceded by a colon
2053 (<literal>:</literal>). If the host part contains a numerical IPv6 address,
2054 it has to be put into angle brackets
2055 (<literal><</literal>, <literal>></literal>).
2060 <term><literal>www.example.com/</literal></term>
2063 is a host-only pattern and will match any request to <literal>www.example.com</literal>,
2064 regardless of which document on that server is requested. So ALL pages in
2065 this domain would be covered by the scope of this action. Note that a
2066 simple <literal>example.com</literal> is different and would NOT match.
2071 <term><literal>www.example.com</literal></term>
2074 means exactly the same. For host-only patterns, the trailing <literal>/</literal> may
2080 <term><literal>www.example.com/index.html</literal></term>
2083 matches all the documents on <literal>www.example.com</literal>
2084 whose name starts with <literal>/index.html</literal>.
2089 <term><literal>www.example.com/index.html$</literal></term>
2092 matches only the single document <literal>/index.html</literal>
2093 on <literal>www.example.com</literal>.
2098 <term><literal>/index.html$</literal></term>
2101 matches the document <literal>/index.html</literal>, regardless of the domain,
2102 i.e. on <emphasis>any</emphasis> web server anywhere.
2107 <term><literal>/</literal></term>
2110 Matches any URL because there's no requirement for either the
2111 domain or the path to match anything.
2116 <term><literal>:8000/</literal></term>
2119 Matches any URL pointing to TCP port 8000.
2124 <term><literal>10.0.0.1/</literal></term>
2127 Matches any URL with the host address <literal>10.0.0.1</literal>.
2128 (Note that the real URL uses plain brackets, not angle brackets.)
2133 <term><literal><2001:db8::1>/</literal></term>
2136 Matches any URL with the host address <literal>2001:db8::1</literal>.
2137 (Note that the real URL uses plain brackets, not angle brackets.)
2142 <term><literal>index.html</literal></term>
2145 matches nothing, since it would be interpreted as a domain name and
2146 there is no top-level domain called <literal>.html</literal>. So its
2154 <!-- ~~~~~ New section ~~~~~ -->
2155 <sect3 id="host-pattern"><title>The Host Pattern</title>
2158 The matching of the host part offers some flexible options: if the
2159 host pattern starts or ends with a dot, it becomes unanchored at that end.
2160 The host pattern is often referred to as domain pattern as it is usually
2161 used to match domain names and not IP addresses.
2167 <term><literal>.example.com</literal></term>
2170 matches any domain with first-level domain <literal>com</literal>
2171 and second-level domain <literal>example</literal>.
2172 For example <literal>www.example.com</literal>,
2173 <literal>example.com</literal> and <literal>foo.bar.baz.example.com</literal>.
2174 Note that it wouldn't match if the second-level domain was <literal>another-example</literal>.
2179 <term><literal>www.</literal></term>
2182 matches any domain that <emphasis>STARTS</emphasis> with
2183 <literal>www.</literal> (It also matches the domain
2184 <literal>www</literal> but most of the time that doesn't matter.)
2189 <term><literal>.example.</literal></term>
2192 matches any domain that <emphasis>CONTAINS</emphasis> <literal>.example.</literal>.
2193 And, by the way, also included would be any files or documents that exist
2194 within that domain since no path limitations are specified. (Correctly
2195 speaking: It matches any FQDN that contains <literal>example</literal> as
2196 a domain.) This might be <literal>www.example.com</literal>,
2197 <literal>news.example.de</literal>, or
2198 <literal>www.example.net/cgi/testing.pl</literal> for instance. All these
2206 Additionally, there are wild-cards that you can use in the domain names
2207 themselves. These work similarly to shell globbing type wild-cards:
2208 <quote>*</quote> represents zero or more arbitrary characters (this is
2210 <ulink url="https://en.wikipedia.org/wiki/Regular_expressions"><quote>Regular
2211 Expression</quote></ulink> based syntax of <quote>.*</quote>),
2212 <quote>?</quote> represents any single character (this is equivalent to the
2213 regular expression syntax of a simple <quote>.</quote>), and you can define
2214 <quote>character classes</quote> in square brackets which is similar to
2215 the same regular expression technique. All of this can be freely mixed:
2220 <term><literal>ad*.example.com</literal></term>
2223 matches <quote>adserver.example.com</quote>,
2224 <quote>ads.example.com</quote>, etc but not <quote>sfads.example.com</quote>
2229 <term><literal>*ad*.example.com</literal></term>
2232 matches all of the above, and then some.
2237 <term><literal>.?pix.com</literal></term>
2240 matches <literal>www.ipix.com</literal>,
2241 <literal>pictures.epix.com</literal>, <literal>a.b.c.d.e.upix.com</literal> etc.
2246 <term><literal>www[1-9a-ez].example.c*</literal></term>
2249 matches <literal>www1.example.com</literal>,
2250 <literal>www4.example.cc</literal>, <literal>wwwd.example.cy</literal>,
2251 <literal>wwwz.example.com</literal> etc., but <emphasis>not</emphasis>
2252 <literal>wwww.example.com</literal>.
2259 While flexible, this is not the sophistication of full regular expression based syntax.
2263 When compiled with FEATURE_PCRE_HOST_PATTERNS patterns can be prefixed with
2264 <quote>PCRE-HOST-PATTERN:</quote> in which case full regular expression
2265 (PCRE) can be used for the host pattern as well.
2270 <!-- ~ End section ~ -->
2273 <!-- ~~~~~ New section ~~~~~ -->
2274 <sect3 id="path-pattern"><title>The Path Pattern</title>
2277 <application>Privoxy</application> uses <quote>modern</quote> POSIX 1003.2
2278 <ulink url="https://en.wikipedia.org/wiki/Regular_expressions"><quote>Regular
2279 Expressions</quote></ulink> for matching the path portion (after the slash),
2280 and is thus more flexible.
2284 There is an <link linkend="regex">Appendix</link> with a brief quick-start into regular
2285 expressions, you also might want to have a look at your operating system's documentation
2286 on regular expressions (try <literal>man re_format</literal>).
2290 Note that the path pattern is automatically left-anchored at the <quote>/</quote>,
2291 i.e. it matches as if it would start with a <quote>^</quote> (regular expression speak
2292 for the beginning of a line).
2296 Please also note that matching in the path is <emphasis>CASE INSENSITIVE</emphasis>
2297 by default, but you can switch to case sensitive at any point in the pattern by using the
2298 <quote>(?-i)</quote> switch: <literal>www.example.com/(?-i)PaTtErN.*</literal> will match
2299 only documents whose path starts with <literal>PaTtErN</literal> in
2300 <emphasis>exactly</emphasis> this capitalization.
2305 <term><literal>.example.com/.*</literal></term>
2308 Is equivalent to just <quote>.example.com</quote>, since any documents
2309 within that domain are matched with or without the <quote>.*</quote>
2310 regular expression. This is redundant
2315 <term><literal>.example.com/.*/index.html$</literal></term>
2318 Will match any page in the domain of <quote>example.com</quote> that is
2319 named <quote>index.html</quote>, and that is part of some path. For
2320 example, it matches <quote>www.example.com/testing/index.html</quote> but
2321 NOT <quote>www.example.com/index.html</quote> because the regular
2322 expression called for at least two <quote>/'s</quote>, thus the path
2323 requirement. It also would match
2324 <quote>www.example.com/testing/index_html</quote>, because of the
2325 special meta-character <quote>.</quote>.
2330 <term><literal>.example.com/(.*/)?index\.html$</literal></term>
2333 This regular expression is conditional so it will match any page
2334 named <quote>index.html</quote> regardless of path which in this case can
2335 have one or more <quote>/'s</quote>. And this one must contain exactly
2336 <quote>.html</quote> (and end with that!).
2341 <term><literal>.example.com/(.*/)(ads|banners?|junk)</literal></term>
2344 This regular expression will match any path of <quote>example.com</quote>
2345 that contains any of the words <quote>ads</quote>, <quote>banner</quote>,
2346 <quote>banners</quote> (because of the <quote>?</quote>) or <quote>junk</quote>.
2347 The path does not have to end in these words, just contain them.
2348 The path has to contain at least two slashes (including the one at the beginning).
2353 <term><literal>.example.com/(.*/)(ads|banners?|junk)/.*\.(jpe?g|gif|png)$</literal></term>
2356 This is very much the same as above, except now it must end in either
2357 <quote>.jpg</quote>, <quote>.jpeg</quote>, <quote>.gif</quote> or <quote>.png</quote>. So this
2358 one is limited to common image formats.
2365 There are many, many good examples to be found in <filename>default.action</filename>,
2366 and more tutorials below in <link linkend="regex">Appendix on regular expressions</link>.
2371 <!-- ~ End section ~ -->
2374 <!-- ~~~~~ New section ~~~~~ -->
2375 <sect3 id="tag-pattern"><title>The Request Tag Pattern</title>
2378 Request tag patterns are used to change the applying actions based on the
2379 request's tags. Tags can be created based on HTTP headers with either
2380 the <link linkend="CLIENT-HEADER-TAGGER">client-header-tagger</link>
2381 or the <link linkend="SERVER-HEADER-TAGGER">server-header-tagger</link> action.
2385 Request tag patterns have to start with <quote>TAG:</quote>, so &my-app;
2386 can tell them apart from other patterns. Everything after the colon
2387 including white space, is interpreted as a regular expression with
2388 path pattern syntax, except that tag patterns aren't left-anchored
2389 automatically (&my-app; doesn't silently add a <quote>^</quote>,
2390 you have to do it yourself if you need it).
2394 To match all requests that are tagged with <quote>foo</quote>
2395 your pattern line should be <quote>TAG:^foo$</quote>,
2396 <quote>TAG:foo</quote> would work as well, but it would also
2397 match requests whose tags contain <quote>foo</quote> somewhere.
2398 <quote>TAG: foo</quote> wouldn't work as it requires white space.
2402 Sections can contain URL and request tag patterns at the same time,
2403 but request tag patterns are checked after the URL patterns and thus
2404 always overrule them, even if they are located before the URL patterns.
2408 Once a new request tag is added, Privoxy checks right away if it's matched by one
2409 of the request tag patterns and updates the action settings accordingly. As a result
2410 request tags can be used to activate other tagger actions, as long as these other
2411 taggers look for headers that haven't already be parsed.
2415 For example you could tag client requests which use the
2416 <literal>POST</literal> method,
2417 then use this tag to activate another tagger that adds a tag if cookies
2418 are sent, and then use a block action based on the cookie tag. This allows
2419 the outcome of one action, to be input into a subsequent action. However if
2420 you'd reverse the position of the described taggers, and activated the
2421 method tagger based on the cookie tagger, no method tags would be created.
2422 The method tagger would look for the request line, but at the time
2423 the cookie tag is created, the request line has already been parsed.
2427 While this is a limitation you should be aware of, this kind of
2428 indirection is seldom needed anyway and even the example doesn't
2429 make too much sense.
2434 <!-- ~~~~~ New section ~~~~~ -->
2435 <sect3 id="negative-tag-patterns"><title>The Negative Request Tag Patterns</title>
2438 To match requests that do not have a certain request tag, specify a negative tag pattern
2439 by prefixing the tag pattern line with either <quote>NO-REQUEST-TAG:</quote>
2440 or <quote>NO-RESPONSE-TAG:</quote> instead of <quote>TAG:</quote>.
2444 Negative request tag patterns created with <quote>NO-REQUEST-TAG:</quote> are checked
2445 after all client headers are scanned, the ones created with <quote>NO-RESPONSE-TAG:</quote>
2446 are checked after all server headers are scanned. In both cases all the created
2447 tags are considered.
2451 <!-- ~~~~~ New section ~~~~~ -->
2452 <sect3 id="client-tag-pattern"><title>The Client Tag Pattern</title>
2454 <!-- XXX: This section contains duplicates content from the
2455 client-specific-tag documentation. -->
2459 This is an experimental feature. The syntax is likely to change in future versions.
2464 Client tag patterns are not set based on HTTP headers but based on
2465 the client's IP address. Users can enable them themselves, but the
2466 Privoxy admin controls which tags are available and what their effect
2471 After a client-specific tag has been defined with the
2472 <link linkend="client-specific-tag">client-specific-tag</link>,
2473 directive, action sections can be activated based on the tag by using a
2474 CLIENT-TAG pattern. The CLIENT-TAG pattern is evaluated at the same priority
2475 as URL patterns, as a result the last matching pattern wins. Tags that
2476 are created based on client or server headers are evaluated later on
2477 and can overrule CLIENT-TAG and URL patterns!
2480 The tag is set for all requests that come from clients that requested
2481 it to be set. Note that "clients" are differentiated by IP address,
2482 if the IP address changes the tag has to be requested again.
2485 Clients can request tags to be set by using the CGI interface <ulink
2486 url="http://config.privoxy.org/client-tags">http://config.privoxy.org/client-tags</ulink>.
2494 # If the admin defined the client-specific-tag circumvent-blocks,
2495 # and the request comes from a client that previously requested
2496 # the tag to be set, overrule all previous +block actions that
2497 # are enabled based on URL to CLIENT-TAG patterns.
2499 CLIENT-TAG:^circumvent-blocks$
2501 # This section is not overruled because it's located after
2503 {+block{Nobody is supposed to request this.}}
2504 example.org/blocked-example-page</screen>
2510 <!-- ~ End section ~ -->
2513 <!-- ~~~~~ New section ~~~~~ -->
2515 <sect2 id="actions">
2516 <title>Actions</title>
2518 All actions are disabled by default, until they are explicitly enabled
2519 somewhere in an actions file. Actions are turned on if preceded with a
2520 <quote>+</quote>, and turned off if preceded with a <quote>-</quote>. So a
2521 <literal>+action</literal> means <quote>do that action</quote>, e.g.
2522 <literal>+block</literal> means <quote>please block URLs that match the
2523 following patterns</quote>, and <literal>-block</literal> means <quote>don't
2524 block URLs that match the following patterns, even if <literal>+block</literal>
2525 previously applied.</quote>
2529 Again, actions are invoked by placing them on a line, enclosed in curly braces and
2530 separated by whitespace, like in
2531 <literal>{+some-action -some-other-action{some-parameter}}</literal>,
2532 followed by a list of URL patterns, one per line, to which they apply.
2533 Together, the actions line and the following pattern lines make up a section
2534 of the actions file.
2538 Actions fall into three categories:
2544 Boolean, i.e the action can only be <quote>enabled</quote> or
2545 <quote>disabled</quote>. Syntax:
2548 +<replaceable class="function">name</replaceable> # enable action <replaceable class="parameter">name</replaceable>
2549 -<replaceable class="function">name</replaceable> # disable action <replaceable class="parameter">name</replaceable></screen>
2551 Example: <literal>+handle-as-image</literal>
2558 Parameterized, where some value is required in order to enable this type of action.
2562 +<replaceable class="function">name</replaceable>{<replaceable class="parameter">param</replaceable>} # enable action and set parameter to <replaceable class="parameter">param</replaceable>,
2563 # overwriting parameter from previous match if necessary
2564 -<replaceable class="function">name</replaceable> # disable action. The parameter can be omitted</screen>
2566 Note that if the URL matches multiple positive forms of a parameterized action,
2567 the last match wins, i.e. the params from earlier matches are simply ignored.
2570 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>
2576 Multi-value. These look exactly like parameterized actions,
2577 but they behave differently: If the action applies multiple times to the
2578 same URL, but with different parameters, <emphasis>all</emphasis> the parameters
2579 from <emphasis>all</emphasis> matches are remembered. This is used for actions
2580 that can be executed for the same request repeatedly, like adding multiple
2581 headers, or filtering through multiple filters. Syntax:
2584 +<replaceable class="function">name</replaceable>{<replaceable class="parameter">param</replaceable>} # enable action and add <replaceable class="parameter">param</replaceable> to the list of parameters
2585 -<replaceable class="function">name</replaceable>{<replaceable class="parameter">param</replaceable>} # remove the parameter <replaceable class="parameter">param</replaceable> from the list of parameters
2586 # If it was the last one left, disable the action.
2587 <replaceable class="parameter">-name</replaceable> # disable this action completely and remove all parameters from the list</screen>
2589 Examples: <literal>+add-header{X-Fun-Header: Some text}</literal> and
2590 <literal>+filter{html-annoyances}</literal>
2597 If nothing is specified in any actions file, no <quote>actions</quote> are
2598 taken. So in this case <application>Privoxy</application> would just be a
2599 normal, non-blocking, non-filtering proxy. You must specifically enable the
2600 privacy and blocking features you need (although the provided default actions
2601 files will give a good starting point).
2605 Later defined action sections always over-ride earlier ones of the same type.
2606 So exceptions to any rules you make, should come in the latter part of the file (or
2607 in a file that is processed later when using multiple actions files such
2608 as <filename>user.action</filename>). For multi-valued actions, the actions
2609 are applied in the order they are specified. Actions files are processed in
2610 the order they are defined in <filename>config</filename> (the default
2611 installation has three actions files). It also quite possible for any given
2612 URL to match more than one <quote>pattern</quote> (because of wildcards and
2613 regular expressions), and thus to trigger more than one set of actions! Last
2617 <!-- start actions listing -->
2619 The list of valid <application>Privoxy</application> actions are:
2623 <!-- ********************************************************** -->
2624 <!-- Please note the below defined actions use id's that are -->
2625 <!-- probably linked from other places, so please don't change. -->
2627 <!-- ********************************************************** -->
2630 <!-- ~~~~~ New section ~~~~~ -->
2632 <sect3 renderas="sect4" id="add-header">
2633 <title>add-header</title>
2637 <term>Typical use:</term>
2639 <para>Confuse log analysis, custom applications</para>
2644 <term>Effect:</term>
2647 Sends a user defined HTTP header to the web server.
2654 <!-- boolean, parameterized, Multi-value -->
2656 <para>Multi-value.</para>
2661 <term>Parameter:</term>
2664 Any string value is possible. Validity of the defined HTTP headers is not checked.
2665 It is recommended that you use the <quote><literal>X-</literal></quote> prefix
2675 This action may be specified multiple times, in order to define multiple
2676 headers. This is rarely needed for the typical user. If you don't know what
2677 <quote>HTTP headers</quote> are, you definitely don't need to worry about this
2681 Headers added by this action are not modified by other actions.
2687 <term>Example usage:</term>
2689 <screen># Add a DNT ("Do not track") header to all requests,
2690 # event to those that already have one.
2692 # This is just an example, not a recommendation.
2694 # There is no reason to believe that user-tracking websites care
2695 # about the DNT header and depending on the User-Agent, adding the
2696 # header may make user-tracking easier.
2697 {+add-header{DNT: 1}}
2705 <!-- ~~~~~ New section ~~~~~ -->
2706 <sect3 renderas="sect4" id="block">
2707 <title>block</title>
2711 <term>Typical use:</term>
2713 <para>Block ads or other unwanted content</para>
2718 <term>Effect:</term>
2721 Requests for URLs to which this action applies are blocked, i.e. the
2722 requests are trapped by &my-app; and the requested URL is never retrieved,
2723 but is answered locally with a substitute page or image, as determined by
2725 linkend="handle-as-image">handle-as-image</link></literal>,
2727 linkend="set-image-blocker">set-image-blocker</link></literal>, and
2729 linkend="handle-as-empty-document">handle-as-empty-document</link></literal> actions.
2737 <!-- boolean, parameterized, Multi-value -->
2739 <para>Parameterized.</para>
2744 <term>Parameter:</term>
2746 <para>A block reason that should be given to the user.</para>
2754 <application>Privoxy</application> sends a special <quote>BLOCKED</quote> page
2755 for requests to blocked pages. This page contains the block reason given as
2756 parameter, a link to find out why the block action applies, and a click-through
2757 to the blocked content (the latter only if the force feature is available and
2761 A very important exception occurs if <emphasis>both</emphasis>
2762 <literal>block</literal> and <literal><link linkend="handle-as-image">handle-as-image</link></literal>,
2763 apply to the same request: it will then be replaced by an image. If
2764 <literal><link linkend="set-image-blocker">set-image-blocker</link></literal>
2765 (see below) also applies, the type of image will be determined by its parameter,
2766 if not, the standard checkerboard pattern is sent.
2769 It is important to understand this process, in order
2770 to understand how <application>Privoxy</application> deals with
2771 ads and other unwanted content. Blocking is a core feature, and one
2772 upon which various other features depend.
2775 The <literal><link linkend="filter">filter</link></literal>
2776 action can perform a very similar task, by <quote>blocking</quote>
2777 banner images and other content through rewriting the relevant URLs in the
2778 document's HTML source, so they don't get requested in the first place.
2779 Note that this is a totally different technique, and it's easy to confuse the two.
2785 <term>Example usage (section):</term>
2787 <screen>{+block{No nasty stuff for you.}}
2788 # Block and replace with "blocked" page
2789 .nasty-stuff.example.com
2791 {+block{Doubleclick banners.} +handle-as-image}
2792 # Block and replace with image
2796 {+block{Layered ads.} +handle-as-empty-document}
2797 # Block and then ignore
2798 adserver.example.net/.*\.js$</screen>
2807 <!-- ~~~~~ New section ~~~~~ -->
2808 <sect3 renderas="sect4" id="change-x-forwarded-for">
2809 <title>change-x-forwarded-for</title>
2813 <term>Typical use:</term>
2815 <para>Improve privacy by not forwarding the source of the request in the HTTP headers.</para>
2820 <term>Effect:</term>
2823 Deletes the <quote>X-Forwarded-For:</quote> HTTP header from the client request,
2831 <!-- Boolean, Parameterized, Multi-value -->
2833 <para>Parameterized.</para>
2838 <term>Parameter:</term>
2842 <para><quote>block</quote> to delete the header.</para>
2846 <quote>add</quote> to create the header (or append
2847 the client's IP address to an already existing one).
2858 It is safe and recommended to use <literal>block</literal>.
2861 Forwarding the source address of the request may make
2862 sense in some multi-user setups but is also a privacy risk.
2867 <term>Example usage:</term>
2869 <screen>+change-x-forwarded-for{block}</screen>
2875 <!-- ~~~~~ New section ~~~~~ -->
2876 <sect3 renderas="sect4" id="client-header-filter">
2877 <title>client-header-filter</title>
2881 <term>Typical use:</term>
2884 Rewrite or remove single client headers.
2890 <term>Effect:</term>
2893 All client headers to which this action applies are filtered on-the-fly through
2894 the specified regular expression based substitutions.
2901 <!-- boolean, parameterized, Multi-value -->
2903 <para>Multi-value.</para>
2908 <term>Parameter:</term>
2911 The name of a client-header filter, as defined in one of the
2912 <link linkend="filter-file">filter files</link>.
2921 Client-header filters are applied to each header on its own, not to
2922 all at once. This makes it easier to diagnose problems, but on the downside
2923 you can't write filters that only change header x if header y's value is z.
2924 You can do that by using tags though.
2927 Client-header filters are executed after the other header actions have finished
2928 and use their output as input.
2931 If the request URI gets changed, &my-app; will detect that and use the new
2932 one. This can be used to rewrite the request destination behind the client's
2933 back, for example to specify a Tor exit relay for certain requests.
2936 Please refer to the <link linkend="filter-file">filter file chapter</link>
2937 to learn which client-header filters are available by default, and how to
2945 <term>Example usage (section):</term>
2948 # Hide Tor exit notation in Host and Referer Headers
2949 {+client-header-filter{hide-tor-exit-notation}}
2959 <!-- ~~~~~ New section ~~~~~ -->
2960 <sect3 renderas="sect4" id="client-header-tagger">
2961 <title>client-header-tagger</title>
2965 <term>Typical use:</term>
2968 Block requests based on their headers.
2974 <term>Effect:</term>
2977 Client headers to which this action applies are filtered on-the-fly through
2978 the specified regular expression based substitutions, the result is used as
2986 <!-- boolean, parameterized, Multi-value -->
2988 <para>Multi-value.</para>
2993 <term>Parameter:</term>
2996 The name of a client-header tagger, as defined in one of the
2997 <link linkend="filter-file">filter files</link>.
3006 Client-header taggers are applied to each header on its own,
3007 and as the header isn't modified, each tagger <quote>sees</quote>
3011 Client-header taggers are the first actions that are executed
3012 and their tags can be used to control every other action.
3018 <term>Example usage (section):</term>
3021 # Tag every request with the User-Agent header
3022 {+client-header-tagger{user-agent}}
3025 # Tagging itself doesn't change the action
3026 # settings, sections with TAG patterns do:
3028 # If it's a download agent, use a different forwarding proxy,
3029 # show the real User-Agent and make sure resume works.
3030 {+forward-override{forward-socks5 10.0.0.2:2222 .} \
3031 -hide-if-modified-since \
3032 -overwrite-last-modified \
3037 TAG:^User-Agent: NetBSD-ftp/
3038 TAG:^User-Agent: Novell ZYPP Installer
3039 TAG:^User-Agent: RPM APT-HTTP/
3040 TAG:^User-Agent: fetch libfetch/
3041 TAG:^User-Agent: Ubuntu APT-HTTP/
3042 TAG:^User-Agent: MPlayer/
3046 # Tag all requests with the Range header set
3047 {+client-header-tagger{range-requests}}
3050 # Disable filtering for the tagged requests.
3052 # With filtering enabled Privoxy would remove the Range headers
3053 # to be able to filter the whole response. The downside is that
3054 # it prevents clients from resuming downloads or skipping over
3055 # parts of multimedia files.
3056 {-filter -deanimate-gifs}
3061 # Tag all requests with the client IP address
3063 # (Technically the client IP address isn't included in the
3064 # client headers but client-header taggers can set it anyway.
3065 # For details see the tagger in default.filter)
3066 {+client-header-tagger{client-ip-address}}
3069 # Change forwarding settings for requests coming from address 10.0.0.1
3070 {+forward-override{forward-socks5 127.0.1.2:2222 .}}
3071 TAG:^IP-ADDRESS: 10\.0\.0\.1$
3080 <!-- ~~~~~ New section ~~~~~ -->
3081 <sect3 renderas="sect4" id="content-type-overwrite">
3082 <title>content-type-overwrite</title>
3086 <term>Typical use:</term>
3088 <para>Stop useless download menus from popping up, or change the browser's rendering mode</para>
3093 <term>Effect:</term>
3096 Replaces the <quote>Content-Type:</quote> HTTP server header.
3103 <!-- Boolean, Parameterized, Multi-value -->
3105 <para>Parameterized.</para>
3110 <term>Parameter:</term>
3122 The <quote>Content-Type:</quote> HTTP server header is used by the
3123 browser to decide what to do with the document. The value of this
3124 header can cause the browser to open a download menu instead of
3125 displaying the document by itself, even if the document's format is
3126 supported by the browser.
3129 The declared content type can also affect which rendering mode
3130 the browser chooses. If XHTML is delivered as <quote>text/html</quote>,
3131 many browsers treat it as yet another broken HTML document.
3132 If it is send as <quote>application/xml</quote>, browsers with
3133 XHTML support will only display it, if the syntax is correct.
3136 If you see a web site that proudly uses XHTML buttons, but sets
3137 <quote>Content-Type: text/html</quote>, you can use &my-app;
3138 to overwrite it with <quote>application/xml</quote> and validate
3139 the web master's claim inside your XHTML-supporting browser.
3140 If the syntax is incorrect, the browser will complain loudly.
3143 You can also go the opposite direction: if your browser prints
3144 error messages instead of rendering a document falsely declared
3145 as XHTML, you can overwrite the content type with
3146 <quote>text/html</quote> and have it rendered as broken HTML document.
3149 By default <literal>content-type-overwrite</literal> only replaces
3150 <quote>Content-Type:</quote> headers that look like some kind of text.
3151 If you want to overwrite it unconditionally, you have to combine it with
3152 <literal><link linkend="force-text-mode">force-text-mode</link></literal>.
3153 This limitation exists for a reason, think twice before circumventing it.
3156 Most of the time it's easier to replace this action with a custom
3157 <literal><link linkend="server-header-filter">server-header filter</link></literal>.
3158 It allows you to activate it for every document of a certain site and it will still
3159 only replace the content types you aimed at.
3162 Of course you can apply <literal>content-type-overwrite</literal>
3163 to a whole site and then make URL based exceptions, but it's a lot
3164 more work to get the same precision.
3170 <term>Example usage (sections):</term>
3172 <screen># Check if www.example.net/ really uses valid XHTML
3173 { +content-type-overwrite{application/xml} }
3176 # but leave the content type unmodified if the URL looks like a style sheet
3177 {-content-type-overwrite}
3178 www.example.net/.*\.css$
3179 www.example.net/.*style
3187 <!-- ~~~~~ New section ~~~~~ -->
3188 <sect3 renderas="sect4" id="crunch-client-header">
3192 <title>crunch-client-header</title>
3196 <term>Typical use:</term>
3198 <para>Remove a client header <application>Privoxy</application> has no dedicated action for.</para>
3203 <term>Effect:</term>
3206 Deletes every header sent by the client that contains the string the user supplied as parameter.
3213 <!-- Boolean, Parameterized, Multi-value -->
3215 <para>Parameterized.</para>
3220 <term>Parameter:</term>
3232 This action allows you to block client headers for which no dedicated
3233 <application>Privoxy</application> action exists.
3234 <application>Privoxy</application> will remove every client header that
3235 contains the string you supplied as parameter.
3238 Regular expressions are <emphasis>not supported</emphasis> and you can't
3239 use this action to block different headers in the same request, unless
3240 they contain the same string.
3243 <literal>crunch-client-header</literal> is only meant for quick tests.
3244 If you have to block several different headers, or only want to modify
3245 parts of them, you should use a
3246 <literal><link linkend="client-header-filter">client-header filter</link></literal>.
3250 Don't block any header without understanding the consequences.
3257 <term>Example usage (section):</term>
3259 <screen># Block the non-existent "Privacy-Violation:" client header
3260 { +crunch-client-header{Privacy-Violation:} }
3269 <!-- ~~~~~ New section ~~~~~ -->
3270 <sect3 renderas="sect4" id="crunch-if-none-match">
3271 <title>crunch-if-none-match</title>
3277 <term>Typical use:</term>
3279 <para>Prevent yet another way to track the user's steps between sessions.</para>
3284 <term>Effect:</term>
3287 Deletes the <quote>If-None-Match:</quote> HTTP client header.
3294 <!-- Boolean, Parameterized, Multi-value -->
3296 <para>Boolean.</para>
3301 <term>Parameter:</term>
3313 Removing the <quote>If-None-Match:</quote> HTTP client header
3314 is useful for filter testing, where you want to force a real
3315 reload instead of getting status code <quote>304</quote> which
3316 would cause the browser to use a cached copy of the page.
3319 It is also useful to make sure the header isn't used as a cookie
3320 replacement (unlikely but possible).
3323 Blocking the <quote>If-None-Match:</quote> header shouldn't cause any
3324 caching problems, as long as the <quote>If-Modified-Since:</quote> header
3325 isn't blocked or missing as well.
3328 It is recommended to use this action together with
3329 <literal><link linkend="hide-if-modified-since">hide-if-modified-since</link></literal>
3331 <literal><link linkend="overwrite-last-modified">overwrite-last-modified</link></literal>.
3337 <term>Example usage (section):</term>
3339 <screen># Let the browser revalidate cached documents but don't
3340 # allow the server to use the revalidation headers for user tracking.
3341 {+hide-if-modified-since{-60} \
3342 +overwrite-last-modified{randomize} \
3343 +crunch-if-none-match}
3352 <!-- ~~~~~ New section ~~~~~ -->
3353 <sect3 renderas="sect4" id="crunch-incoming-cookies">
3354 <title>crunch-incoming-cookies</title>
3358 <term>Typical use:</term>
3361 Prevent the web server from setting HTTP cookies on your system
3367 <term>Effect:</term>
3370 Deletes any <quote>Set-Cookie:</quote> HTTP headers from server replies.
3377 <!-- Boolean, Parameterized, Multi-value -->
3379 <para>Boolean.</para>
3384 <term>Parameter:</term>
3396 This action is only concerned with <emphasis>incoming</emphasis> HTTP cookies. For
3397 <emphasis>outgoing</emphasis> HTTP cookies, use
3398 <literal><link linkend="crunch-outgoing-cookies">crunch-outgoing-cookies</link></literal>.
3399 Use <emphasis>both</emphasis> to disable HTTP cookies completely.
3402 It makes <emphasis>no sense at all</emphasis> to use this action in conjunction
3403 with the <literal><link linkend="session-cookies-only">session-cookies-only</link></literal> action,
3404 since it would prevent the session cookies from being set. See also
3405 <literal><link linkend="filter-content-cookies">filter-content-cookies</link></literal>.
3411 <term>Example usage:</term>
3413 <screen>+crunch-incoming-cookies</screen>
3420 <!-- ~~~~~ New section ~~~~~ -->
3421 <sect3 renderas="sect4" id="crunch-server-header">
3422 <title>crunch-server-header</title>
3428 <term>Typical use:</term>
3430 <para>Remove a server header <application>Privoxy</application> has no dedicated action for.</para>
3435 <term>Effect:</term>
3438 Deletes every header sent by the server that contains the string the user supplied as parameter.
3445 <!-- Boolean, Parameterized, Multi-value -->
3447 <para>Parameterized.</para>
3452 <term>Parameter:</term>
3464 This action allows you to block server headers for which no dedicated
3465 <application>Privoxy</application> action exists. <application>Privoxy</application>
3466 will remove every server header that contains the string you supplied as parameter.
3469 Regular expressions are <emphasis>not supported</emphasis> and you can't
3470 use this action to block different headers in the same request, unless
3471 they contain the same string.
3474 <literal>crunch-server-header</literal> is only meant for quick tests.
3475 If you have to block several different headers, or only want to modify
3476 parts of them, you should use a custom
3477 <literal><link linkend="server-header-filter">server-header filter</link></literal>.
3481 Don't block any header without understanding the consequences.
3488 <term>Example usage (section):</term>
3490 <screen># Crunch server headers that try to prevent caching
3491 { +crunch-server-header{no-cache} }
3500 <!-- ~~~~~ New section ~~~~~ -->
3501 <sect3 renderas="sect4" id="crunch-outgoing-cookies">
3502 <title>crunch-outgoing-cookies</title>
3506 <term>Typical use:</term>
3509 Prevent the web server from reading any HTTP cookies from your system
3515 <term>Effect:</term>
3518 Deletes any <quote>Cookie:</quote> HTTP headers from client requests.
3525 <!-- Boolean, Parameterized, Multi-value -->
3527 <para>Boolean.</para>
3532 <term>Parameter:</term>
3544 This action is only concerned with <emphasis>outgoing</emphasis> HTTP cookies. For
3545 <emphasis>incoming</emphasis> HTTP cookies, use
3546 <literal><link linkend="crunch-incoming-cookies">crunch-incoming-cookies</link></literal>.
3547 Use <emphasis>both</emphasis> to disable HTTP cookies completely.
3550 It makes <emphasis>no sense at all</emphasis> to use this action in conjunction
3551 with the <literal><link linkend="session-cookies-only">session-cookies-only</link></literal> action,
3552 since it would prevent the session cookies from being read.
3558 <term>Example usage:</term>
3560 <screen>+crunch-outgoing-cookies</screen>
3568 <!-- ~~~~~ New section ~~~~~ -->
3569 <sect3 renderas="sect4" id="deanimate-gifs">
3570 <title>deanimate-gifs</title>
3574 <term>Typical use:</term>
3576 <para>Stop those annoying, distracting animated GIF images.</para>
3581 <term>Effect:</term>
3584 De-animate GIF animations, i.e. reduce them to their first or last image.
3591 <!-- boolean, parameterized, Multi-value -->
3593 <para>Parameterized.</para>
3598 <term>Parameter:</term>
3601 <quote>last</quote> or <quote>first</quote>
3610 This will also shrink the images considerably (in bytes, not pixels!). If
3611 the option <quote>first</quote> is given, the first frame of the animation
3612 is used as the replacement. If <quote>last</quote> is given, the last
3613 frame of the animation is used instead, which probably makes more sense for
3614 most banner animations, but also has the risk of not showing the entire
3615 last frame (if it is only a delta to an earlier frame).
3618 You can safely use this action with patterns that will also match non-GIF
3619 objects, because no attempt will be made at anything that doesn't look like
3626 <term>Example usage:</term>
3628 <screen>+deanimate-gifs{last}</screen>
3635 <!-- ~~~~~ New section ~~~~~ -->
3636 <sect3 renderas="sect4" id="delay-response">
3637 <title>delay-response</title>
3641 <term>Typical use:</term>
3643 <para>Delay responses to the client to reduce the load</para>
3648 <term>Effect:</term>
3651 Delays responses to the client by sending the response in ca. 10 byte chunks.
3658 <!-- boolean, parameterized, Multi-value -->
3660 <para>Parameterized.</para>
3665 <term>Parameter:</term>
3668 <quote>Number of milliseconds</quote>
3677 Sometimes when JavaScript code is used to fetch advertisements
3678 it doesn't respect Privoxy's blocks and retries to fetch the
3679 same resource again causing unnecessary load on the client.
3682 This action delays responses to the client and can be combined
3683 with <literal><link linkend="block">blocks</link></literal>
3684 to slow down the JavaScript code, thus reducing
3685 the load on the client.
3688 When used without <literal><link linkend="block">blocks</link></literal>
3689 the action can also be used to simulate a slow internet connection.
3695 <term>Example usage:</term>
3697 <screen>+delay-response{100}</screen>
3704 <!-- ~~~~~ New section ~~~~~ -->
3705 <sect3 renderas="sect4" id="downgrade-http-version">
3706 <title>downgrade-http-version</title>
3710 <term>Typical use:</term>
3712 <para>Work around (very rare) problems with HTTP/1.1</para>
3717 <term>Effect:</term>
3720 Downgrades HTTP/1.1 client requests and server replies to HTTP/1.0.
3727 <!-- boolean, parameterized, Multi-value -->
3729 <para>Boolean.</para>
3734 <term>Parameter:</term>
3746 This is a left-over from the time when <application>Privoxy</application>
3747 didn't support important HTTP/1.1 features well. It is left here for the
3748 unlikely case that you experience HTTP/1.1-related problems with some server
3752 Note that enabling this action is only a workaround. It should not
3753 be enabled for sites that work without it. While it shouldn't break
3754 any pages, it has an (usually negative) performance impact.
3757 If you come across a site where enabling this action helps, please report it,
3758 so the cause of the problem can be analyzed. If the problem turns out to be
3759 caused by a bug in <application>Privoxy</application> it should be
3760 fixed so the following release works without the work around.
3766 <term>Example usage (section):</term>
3768 <screen>{+downgrade-http-version}
3769 problem-host.example.com</screen>
3777 <!-- ~~~~~ New section ~~~~~ -->
3778 <sect3 renderas="sect4" id="external-filter">
3779 <title>external-filter</title>
3783 <term>Typical use:</term>
3785 <para>Modify content using a programming language of your choice.</para>
3790 <term>Effect:</term>
3793 All instances of text-based type, most notably HTML and JavaScript, to which
3794 this action applies, can be filtered on-the-fly through the specified external
3796 By default plain text documents are exempted from filtering, because web
3797 servers often use the <literal>text/plain</literal> MIME type for all files
3798 whose type they don't know.)
3805 <!-- boolean, parameterized, Multi-value -->
3807 <para>Multi-value.</para>
3812 <term>Parameter:</term>
3815 The name of an external content filter, as defined in the
3816 <link linkend="filter-file">filter file</link>.
3817 External filters can be defined in one or more files as defined by the
3818 <literal><link linkend="filterfile">filterfile</link></literal>
3819 option in the <link linkend="config">config file</link>.
3822 When used in its negative form,
3823 and without parameters, <emphasis>all</emphasis> filtering with external
3824 filters is completely disabled.
3833 External filters are scripts or programs that can modify the content in
3834 case common <literal><link linkend="filter">filters</link></literal>
3835 aren't powerful enough. With the exception that this action doesn't
3836 use pcrs-based filters, the notes in the
3837 <literal><link linkend="filter">filter</link></literal> section apply.
3841 Currently external filters are executed with &my-app;'s privileges.
3842 Only use external filters you understand and trust.
3846 This feature is experimental, the <literal><link
3847 linkend="external-filter-syntax">syntax</link></literal>
3848 may change in the future.
3855 <term>Example usage:</term>
3857 <screen>+external-filter{fancy-filter}</screen>
3863 <!-- ~~~~~ New section ~~~~~ -->
3864 <sect3 renderas="sect4" id="fast-redirects">
3865 <title>fast-redirects</title>
3869 <term>Typical use:</term>
3871 <para>Fool some click-tracking scripts and speed up indirect links.</para>
3876 <term>Effect:</term>
3879 Detects redirection URLs and redirects the browser without contacting
3880 the redirection server first.
3887 <!-- boolean, parameterized, Multi-value -->
3889 <para>Parameterized.</para>
3894 <term>Parameter:</term>
3899 <quote>simple-check</quote> to just search for the string <quote>http://</quote>
3900 to detect redirection URLs.
3905 <quote>check-decoded-url</quote> to decode URLs (if necessary) before searching
3906 for redirection URLs.
3917 Many sites, like yahoo.com, don't just link to other sites. Instead, they
3918 will link to some script on their own servers, giving the destination as a
3919 parameter, which will then redirect you to the final target. URLs
3920 resulting from this scheme typically look like:
3921 <quote>http://www.example.org/click-tracker.cgi?target=http%3a//www.example.net/</quote>.
3924 Sometimes, there are even multiple consecutive redirects encoded in the
3925 URL. These redirections via scripts make your web browsing more traceable,
3926 since the server from which you follow such a link can see where you go
3927 to. Apart from that, valuable bandwidth and time is wasted, while your
3928 browser asks the server for one redirect after the other. Plus, it feeds
3932 This feature is currently not very smart and is scheduled for improvement.
3933 If it is enabled by default, you will have to create some exceptions to
3934 this action. It can lead to failures in several ways:
3937 Not every URLs with other URLs as parameters is evil.
3938 Some sites offer a real service that requires this information to work.
3939 For example a validation service needs to know, which document to validate.
3940 <literal>fast-redirects</literal> assumes that every URL parameter that
3941 looks like another URL is a redirection target, and will always redirect to
3942 the last one. Most of the time the assumption is correct, but if it isn't,
3943 the user gets redirected anyway.
3946 Another failure occurs if the URL contains other parameters after the URL parameter.
3948 <quote>http://www.example.org/?redirect=http%3a//www.example.net/&foo=bar</quote>.
3949 contains the redirection URL <quote>http://www.example.net/</quote>,
3950 followed by another parameter. <literal>fast-redirects</literal> doesn't know that
3951 and will cause a redirect to <quote>http://www.example.net/&foo=bar</quote>.
3952 Depending on the target server configuration, the parameter will be silently ignored
3953 or lead to a <quote>page not found</quote> error. You can prevent this problem by
3954 first using the <literal><link linkend="redirect">redirect</link></literal> action
3955 to remove the last part of the URL, but it requires a little effort.
3958 To detect a redirection URL, <literal>fast-redirects</literal> only
3959 looks for the string <quote>http://</quote>, either in plain text
3960 (invalid but often used) or encoded as <quote>http%3a//</quote>.
3961 Some sites use their own URL encoding scheme, encrypt the address
3962 of the target server or replace it with a database id. In these cases
3963 <literal>fast-redirects</literal> is fooled and the request reaches the
3964 redirection server where it probably gets logged.
3970 <term>Example usage:</term>
3973 { +fast-redirects{simple-check} }
3976 { +fast-redirects{check-decoded-url} }
3977 another.example.com/testing</screen>
3985 <!-- ~~~~~ New section ~~~~~ -->
3986 <sect3 renderas="sect4" id="filter">
3987 <title>filter</title>
3991 <term>Typical use:</term>
3993 <para>Get rid of HTML and JavaScript annoyances, banner advertisements (by size),
3994 do fun text replacements, add personalized effects, etc.</para>
3999 <term>Effect:</term>
4002 All instances of text-based type, most notably HTML and JavaScript, to which
4003 this action applies, can be filtered on-the-fly through the specified regular
4004 expression based substitutions. (Note: as of version 3.0.3 plain text documents
4005 are exempted from filtering, because web servers often use the
4006 <literal>text/plain</literal> MIME type for all files whose type they don't know.)
4013 <!-- boolean, parameterized, Multi-value -->
4015 <para>Multi-value.</para>
4020 <term>Parameter:</term>
4023 The name of a content filter, as defined in the <link linkend="filter-file">filter file</link>.
4024 Filters can be defined in one or more files as defined by the
4025 <literal><link linkend="filterfile">filterfile</link></literal>
4026 option in the <link linkend="config">config file</link>.
4027 <filename>default.filter</filename> is the collection of filters
4028 supplied by the developers. Locally defined filters should go
4029 in their own file, such as <filename>user.filter</filename>.
4032 When used in its negative form,
4033 and without parameters, <emphasis>all</emphasis> filtering is completely disabled.
4042 For your convenience, there are a number of pre-defined filters available
4043 in the distribution filter file that you can use. See the examples below for
4047 Filtering requires buffering the page content, which may appear to
4048 slow down page rendering since nothing is displayed until all content has
4049 passed the filters. (The total time until the page is completely rendered
4050 doesn't change much, but it may be perceived as slower since the page is
4051 not incrementally displayed.)
4052 This effect will be more noticeable on slower connections.
4055 <quote>Rolling your own</quote>
4056 filters requires a knowledge of
4057 <ulink url="https://en.wikipedia.org/wiki/Regular_expressions"><quote>Regular
4058 Expressions</quote></ulink> and
4059 <ulink url="https://en.wikipedia.org/wiki/Html"><quote>HTML</quote></ulink>.
4060 This is very powerful feature, and potentially very intrusive.
4061 Filters should be used with caution, and where an equivalent
4062 <quote>action</quote> is not available.
4065 The amount of data that can be filtered is limited to the
4066 <literal><link linkend="buffer-limit">buffer-limit</link></literal>
4067 option in the main <link linkend="config">config file</link>. The
4068 default is 4096 KB (4 Megs). Once this limit is exceeded, the buffered
4069 data, and all pending data, is passed through unfiltered.
4072 Inappropriate MIME types, such as zipped files, are not filtered at all.
4073 (Again, only text-based types except plain text). Encrypted SSL data
4074 (from HTTPS servers) cannot be filtered either, since this would violate
4075 the integrity of the secure transaction. In some situations it might
4076 be necessary to protect certain text, like source code, from filtering
4077 by defining appropriate <literal>-filter</literal> exceptions.
4080 Compressed content can't be filtered either, but if &my-app;
4081 is compiled with zlib support and a supported compression algorithm
4082 is used (gzip or deflate), &my-app; can first decompress the content
4086 If you use a &my-app; version without zlib support, but want filtering to work on
4087 as much documents as possible, even those that would normally be sent compressed,
4088 you must use the <literal><link linkend="prevent-compression">prevent-compression</link></literal>
4089 action in conjunction with <literal>filter</literal>.
4092 Content filtering can achieve some of the same effects as the
4093 <literal><link linkend="block">block</link></literal>
4094 action, i.e. it can be used to block ads and banners. But the mechanism
4095 works quite differently. One effective use, is to block ad banners
4096 based on their size (see below), since many of these seem to be somewhat
4100 <link linkend="contact">Feedback</link> with suggestions for new or
4101 improved filters is particularly welcome!
4104 The below list has only the names and a one-line description of each
4105 predefined filter. There are <link linkend="predefined-filters">more
4106 verbose explanations</link> of what these filters do in the <link
4107 linkend="filter-file">filter file chapter</link>.
4113 <term>Example usage (with filters from the distribution <filename>default.filter</filename> file).
4114 See <link linkend="PREDEFINED-FILTERS">the Predefined Filters section</link> for
4115 more explanation on each:</term>
4118 <anchor id="filter-js-annoyances">
4120 <screen>+filter{js-annoyances} # Get rid of particularly annoying JavaScript abuse.</screen>
4122 <anchor id="filter-js-events">
4124 <screen>+filter{js-events} # Kill JavaScript event bindings and timers (Radically destructive! Only for extra nasty sites).</screen>
4126 <anchor id="filter-html-annoyances">
4128 <screen>+filter{html-annoyances} # Get rid of particularly annoying HTML abuse.</screen>
4130 <anchor id="filter-content-cookies">
4132 <screen>+filter{content-cookies} # Kill cookies that come in the HTML or JS content.</screen>
4134 <anchor id="filter-refresh-tags">
4136 <screen>+filter{refresh-tags} # Kill automatic refresh tags if refresh time is larger than 9 seconds.</screen>
4138 <anchor id="filter-unsolicited-popups">
4140 <screen>+filter{unsolicited-popups} # Disable only unsolicited pop-up windows.</screen>
4142 <anchor id="filter-all-popups">
4144 <screen>+filter{all-popups} # Kill all popups in JavaScript and HTML.</screen>
4146 <anchor id="filter-img-reorder">
4148 <screen>+filter{img-reorder} # Reorder attributes in <img> tags to make the banners-by-* filters more effective.</screen>
4150 <anchor id="filter-banners-by-size">
4152 <screen>+filter{banners-by-size} # Kill banners by size.</screen>
4154 <anchor id="filter-banners-by-link">
4156 <screen>+filter{banners-by-link} # Kill banners by their links to known clicktrackers.</screen>
4158 <anchor id="filter-webbugs">
4160 <screen>+filter{webbugs} # Squish WebBugs (1x1 invisible GIFs used for user tracking).</screen>
4162 <anchor id="filter-tiny-textforms">
4164 <screen>+filter{tiny-textforms} # Extend those tiny textareas up to 40x80 and kill the hard wrap.</screen>
4166 <anchor id="filter-jumping-windows">
4168 <screen>+filter{jumping-windows} # Prevent windows from resizing and moving themselves.</screen>
4170 <anchor id="filter-frameset-borders">
4172 <screen>+filter{frameset-borders} # Give frames a border and make them resizable.</screen>
4174 <anchor id="filter-iframes">
4176 <screen>+filter{iframes} # Removes all detected iframes. Should only be enabled for individual sites.</screen>
4178 <anchor id="filter-demoronizer">
4180 <screen>+filter{demoronizer} # Fix MS's non-standard use of standard charsets.</screen>
4182 <anchor id="filter-shockwave-flash">
4184 <screen>+filter{shockwave-flash} # Kill embedded Shockwave Flash objects.</screen>
4186 <anchor id="filter-quicktime-kioskmode">
4188 <screen>+filter{quicktime-kioskmode} # Make Quicktime movies saveable.</screen>
4190 <anchor id="filter-fun">
4192 <screen>+filter{fun} # Text replacements for subversive browsing fun!</screen>
4194 <anchor id="filter-crude-parental">
4196 <screen>+filter{crude-parental} # Crude parental filtering. Note that this filter doesn't work reliably.</screen>
4198 <anchor id="filter-ie-exploits">
4200 <screen>+filter{ie-exploits} # Disable some known Internet Explorer bug exploits.</screen>
4202 <anchor id="filter-site-specifics">
4204 <screen>+filter{site-specifics} # Cure for site-specific problems. Don't apply generally!</screen>
4206 <anchor id="filter-no-ping">
4208 <screen>+filter{no-ping} # Removes non-standard ping attributes in <a> and <area> tags.</screen>
4210 <anchor id="filter-google">
4212 <screen>+filter{google} # CSS-based block for Google text ads. Also removes a width limitation and the toolbar advertisement.</screen>
4214 <anchor id="filter-yahoo">
4216 <screen>+filter{yahoo} # CSS-based block for Yahoo text ads. Also removes a width limitation.</screen>
4218 <anchor id="filter-msn">
4220 <screen>+filter{msn} # CSS-based block for MSN text ads. Also removes tracking URLs and a width limitation.</screen>
4222 <anchor id="filter-blogspot">
4224 <screen>+filter{blogspot} # Cleans up some Blogspot blogs. Read the fine print before using this.</screen>
4231 <!-- ~~~~~ New section ~~~~~ -->
4232 <sect3 renderas="sect4" id="force-text-mode">
4233 <title>force-text-mode</title>
4239 <term>Typical use:</term>
4241 <para>Force <application>Privoxy</application> to treat a document as if it was in some kind of <emphasis>text</emphasis> format. </para>
4246 <term>Effect:</term>
4249 Declares a document as text, even if the <quote>Content-Type:</quote> isn't detected as such.
4256 <!-- Boolean, Parameterized, Multi-value -->
4258 <para>Boolean.</para>
4263 <term>Parameter:</term>
4275 As explained <literal><link linkend="filter">above</link></literal>,
4276 <application>Privoxy</application> tries to only filter files that are
4277 in some kind of text format. The same restrictions apply to
4278 <literal><link linkend="content-type-overwrite">content-type-overwrite</link></literal>.
4279 <literal>force-text-mode</literal> declares a document as text,
4280 without looking at the <quote>Content-Type:</quote> first.
4284 Think twice before activating this action. Filtering binary data
4285 with regular expressions can cause file damage.
4292 <term>Example usage:</term>
4303 <!-- ~~~~~ New section ~~~~~ -->
4304 <sect3 renderas="sect4" id="forward-override">
4305 <title>forward-override</title>
4311 <term>Typical use:</term>
4313 <para>Change the forwarding settings based on User-Agent or request origin</para>
4318 <term>Effect:</term>
4321 Overrules the forward directives in the configuration file.
4328 <!-- Boolean, Parameterized, Multi-value -->
4330 <para>Parameterized.</para>
4335 <term>Parameter:</term>
4339 <para><quote>forward .</quote> to use a direct connection without any additional proxies.</para>
4343 <quote>forward 127.0.0.1:8123</quote> to use the HTTP proxy listening at 127.0.0.1 port 8123.
4348 <quote>forward-socks4a 127.0.0.1:9050 .</quote> to use the socks4a proxy listening at
4349 127.0.0.1 port 9050. Replace <quote>forward-socks4a</quote> with <quote>forward-socks4</quote>
4350 to use a socks4 connection (with local DNS resolution) instead, use <quote>forward-socks5</quote>
4351 for socks5 connections (with remote DNS resolution).
4356 <quote>forward-socks4a 127.0.0.1:9050 proxy.example.org:8000</quote> to use the socks4a proxy
4357 listening at 127.0.0.1 port 9050 to reach the HTTP proxy listening at proxy.example.org port 8000.
4358 Replace <quote>forward-socks4a</quote> with <quote>forward-socks4</quote> to use a socks4 connection
4359 (with local DNS resolution) instead, use <quote>forward-socks5</quote>
4360 for socks5 connections (with remote DNS resolution).
4365 <quote>forward-webserver 127.0.0.1:80</quote> to use the HTTP
4366 server listening at 127.0.0.1 port 80 without adjusting the
4370 This makes it more convenient to use Privoxy to make
4371 existing websites available as onion services as well.
4374 Many websites serve content with hardcoded URLs and
4375 can't be easily adjusted to change the domain based
4376 on the one used by the client.
4379 Putting Privoxy between Tor and the webserver (or an stunnel
4380 that forwards to the webserver) allows to rewrite headers and
4381 content to make client and server happy at the same time.
4384 Using Privoxy for webservers that are only reachable through
4385 onion addresses and whose location is supposed to be secret
4386 is not recommended and should not be necessary anyway.
4397 This action takes parameters similar to the
4398 <link linkend="forwarding">forward</link> directives in the configuration
4399 file, but without the URL pattern. It can be used as replacement, but normally it's only
4400 used in cases where matching based on the request URL isn't sufficient.
4404 Please read the description for the <link linkend="forwarding">forward</link> directives before
4405 using this action. Forwarding to the wrong people will reduce your privacy and increase the
4406 chances of man-in-the-middle attacks.
4409 If the ports are missing or invalid, default values will be used. This might change
4410 in the future and you shouldn't rely on it. Otherwise incorrect syntax causes Privoxy
4411 to exit. Due to design limitations, invalid parameter syntax isn't detected until the
4412 action is used the first time.
4415 Use the <ulink url="http://config.privoxy.org/show-url-info">show-url-info CGI page</ulink>
4416 to verify that your forward settings do what you thought the do.
4423 <term>Example usage:</term>
4426 # Use an ssh tunnel for requests previously tagged as
4427 # <quote>User-Agent: fetch libfetch/2.0</quote> and make sure
4428 # resuming downloads continues to work.
4430 # This way you can continue to use Tor for your normal browsing,
4431 # without overloading the Tor network with your FreeBSD ports updates
4432 # or downloads of bigger files like ISOs.
4434 # Note that HTTP headers are easy to fake and therefore their
4435 # values are as (un)trustworthy as your clients and users.
4436 {+forward-override{forward-socks5 10.0.0.2:2222 .} \
4437 -hide-if-modified-since \
4438 -overwrite-last-modified \
4440 TAG:^User-Agent: fetch libfetch/2\.0$
4448 <!-- ~~~~~ New section ~~~~~ -->
4449 <sect3 renderas="sect4" id="handle-as-empty-document">
4450 <title>handle-as-empty-document</title>
4456 <term>Typical use:</term>
4458 <para>Mark URLs that should be replaced by empty documents <emphasis>if they get blocked</emphasis></para>
4463 <term>Effect:</term>
4466 This action alone doesn't do anything noticeable. It just marks URLs.
4467 If the <literal><link linkend="block">block</link></literal> action <emphasis>also applies</emphasis>,
4468 the presence or absence of this mark decides whether an HTML <quote>BLOCKED</quote>
4469 page, or an empty document will be sent to the client as a substitute for the blocked content.
4470 The <emphasis>empty</emphasis> document isn't literally empty, but actually contains a single space.
4477 <!-- Boolean, Parameterized, Multi-value -->
4479 <para>Boolean.</para>
4484 <term>Parameter:</term>
4496 Some browsers complain about syntax errors if JavaScript documents
4497 are blocked with <application>Privoxy's</application>
4498 default HTML page; this option can be used to silence them.
4499 And of course this action can also be used to eliminate the &my-app;
4500 BLOCKED message in frames.
4503 The content type for the empty document can be specified with
4504 <literal><link linkend="content-type-overwrite">content-type-overwrite{}</link></literal>,
4505 but usually this isn't necessary.
4511 <term>Example usage:</term>
4513 <screen># Block all documents on example.org that end with ".js",
4514 # but send an empty document instead of the usual HTML message.
4515 {+block{Blocked JavaScript} +handle-as-empty-document}
4524 <!-- ~~~~~ New section ~~~~~ -->
4525 <sect3 renderas="sect4" id="handle-as-image">
4526 <title>handle-as-image</title>
4530 <term>Typical use:</term>
4532 <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>
4537 <term>Effect:</term>
4540 This action alone doesn't do anything noticeable. It just marks URLs as images.
4541 If the <literal><link linkend="block">block</link></literal> action <emphasis>also applies</emphasis>,
4542 the presence or absence of this mark decides whether an HTML <quote>blocked</quote>
4543 page, or a replacement image (as determined by the <literal><link
4544 linkend="set-image-blocker">set-image-blocker</link></literal> action) will be sent to the
4545 client as a substitute for the blocked content.
4552 <!-- Boolean, Parameterized, Multi-value -->
4554 <para>Boolean.</para>
4559 <term>Parameter:</term>
4571 The below generic example section is actually part of <filename>default.action</filename>.
4572 It marks all URLs with well-known image file name extensions as images and should
4576 Users will probably only want to use the handle-as-image action in conjunction with
4577 <literal><link linkend="block">block</link></literal>, to block sources of banners, whose URLs don't
4578 reflect the file type, like in the second example section.
4581 Note that you cannot treat HTML pages as images in most cases. For instance, (in-line) ad
4582 frames require an HTML page to be sent, or they won't display properly.
4583 Forcing <literal>handle-as-image</literal> in this situation will not replace the
4584 ad frame with an image, but lead to error messages.
4590 <term>Example usage (sections):</term>
4592 <screen># Generic image extensions:
4595 /.*\.(gif|jpg|jpeg|png|bmp|ico)$
4597 # These don't look like images, but they're banners and should be
4598 # blocked as images:
4600 {+block{Nasty banners.} +handle-as-image}
4601 nasty-banner-server.example.com/junk.cgi\?output=trash
4609 <!-- ~~~~~ New section ~~~~~ -->
4610 <sect3 renderas="sect4" id="hide-accept-language">
4611 <title>hide-accept-language</title>
4617 <term>Typical use:</term>
4619 <para>Pretend to use different language settings.</para>
4624 <term>Effect:</term>
4627 Deletes or replaces the <quote>Accept-Language:</quote> HTTP header in client requests.
4634 <!-- Boolean, Parameterized, Multi-value -->
4636 <para>Parameterized.</para>
4641 <term>Parameter:</term>
4644 Keyword: <quote>block</quote>, or any user defined value.
4653 Faking the browser's language settings can be useful to make a
4654 foreign User-Agent set with
4655 <literal><link linkend="hide-user-agent">hide-user-agent</link></literal>
4659 However some sites with content in different languages check the
4660 <quote>Accept-Language:</quote> to decide which one to take by default.
4661 Sometimes it isn't possible to later switch to another language without
4662 changing the <quote>Accept-Language:</quote> header first.
4665 Therefore it's a good idea to either only change the
4666 <quote>Accept-Language:</quote> header to languages you understand,
4667 or to languages that aren't wide spread.
4670 Before setting the <quote>Accept-Language:</quote> header
4671 to a rare language, you should consider that it helps to
4672 make your requests unique and thus easier to trace.
4673 If you don't plan to change this header frequently,
4674 you should stick to a common language.
4680 <term>Example usage (section):</term>
4682 <screen># Pretend to use Canadian language settings.
4683 {+hide-accept-language{en-ca} \
4684 +hide-user-agent{Mozilla/5.0 (X11; U; OpenBSD i386; en-CA; rv:1.8.0.4) Gecko/20060628 Firefox/1.5.0.4} \
4694 <!-- ~~~~~ New section ~~~~~ -->
4695 <sect3 renderas="sect4" id="hide-content-disposition">
4696 <title>hide-content-disposition</title>
4702 <term>Typical use:</term>
4704 <para>Prevent download menus for content you prefer to view inside the browser.</para>
4709 <term>Effect:</term>
4712 Deletes or replaces the <quote>Content-Disposition:</quote> HTTP header set by some servers.
4719 <!-- Boolean, Parameterized, Multi-value -->
4721 <para>Parameterized.</para>
4726 <term>Parameter:</term>
4729 Keyword: <quote>block</quote>, or any user defined value.
4738 Some servers set the <quote>Content-Disposition:</quote> HTTP header for
4739 documents they assume you want to save locally before viewing them.
4740 The <quote>Content-Disposition:</quote> header contains the file name
4741 the browser is supposed to use by default.
4744 In most browsers that understand this header, it makes it impossible to
4745 <emphasis>just view</emphasis> the document, without downloading it first,
4746 even if it's just a simple text file or an image.
4749 Removing the <quote>Content-Disposition:</quote> header helps
4750 to prevent this annoyance, but some browsers additionally check the
4751 <quote>Content-Type:</quote> header, before they decide if they can
4752 display a document without saving it first. In these cases, you have
4753 to change this header as well, before the browser stops displaying
4757 It is also possible to change the server's file name suggestion
4758 to another one, but in most cases it isn't worth the time to set
4762 This action will probably be removed in the future,
4763 use server-header filters instead.
4769 <term>Example usage:</term>
4771 <screen># Disarm the download link in Sourceforge's patch tracker
4773 +content-type-overwrite{text/plain}\
4774 +hide-content-disposition{block} }
4775 .sourceforge.net/tracker/download\.php</screen>
4782 <!-- ~~~~~ New section ~~~~~ -->
4783 <sect3 renderas="sect4" id="hide-if-modified-since">
4784 <title>hide-if-modified-since</title>
4790 <term>Typical use:</term>
4792 <para>Prevent yet another way to track the user's steps between sessions.</para>
4797 <term>Effect:</term>
4800 Deletes the <quote>If-Modified-Since:</quote> HTTP client header or modifies its value.
4807 <!-- Boolean, Parameterized, Multi-value -->
4809 <para>Parameterized.</para>
4814 <term>Parameter:</term>
4817 Keyword: <quote>block</quote>, or a user defined value that specifies a range of hours.
4826 Removing this header is useful for filter testing, where you want to force a real
4827 reload instead of getting status code <quote>304</quote>, which would cause the
4828 browser to use a cached copy of the page.
4831 Instead of removing the header, <literal>hide-if-modified-since</literal> can
4832 also add or subtract a random amount of time to/from the header's value.
4833 You specify a range of minutes where the random factor should be chosen from and
4834 <application>Privoxy</application> does the rest. A negative value means
4835 subtracting, a positive value adding.
4838 Randomizing the value of the <quote>If-Modified-Since:</quote> makes
4839 it less likely that the server can use the time as a cookie replacement,
4840 but you will run into caching problems if the random range is too high.
4843 It is a good idea to only use a small negative value and let
4844 <literal><link linkend="overwrite-last-modified">overwrite-last-modified</link></literal>
4845 handle the greater changes.
4848 It is also recommended to use this action together with
4849 <literal><link linkend="crunch-if-none-match">crunch-if-none-match</link></literal>,
4850 otherwise it's more or less pointless.
4856 <term>Example usage (section):</term>
4858 <screen># Let the browser revalidate but make tracking based on the time less likely.
4859 {+hide-if-modified-since{-60} \
4860 +overwrite-last-modified{randomize} \
4861 +crunch-if-none-match}
4869 <!-- ~~~~~ New section ~~~~~ -->
4870 <sect3 renderas="sect4" id="hide-from-header">
4871 <title>hide-from-header</title>
4875 <term>Typical use:</term>
4877 <para>Keep your (old and ill) browser from telling web servers your email address</para>
4882 <term>Effect:</term>
4885 Deletes any existing <quote>From:</quote> HTTP header, or replaces it with the
4893 <!-- Boolean, Parameterized, Multi-value -->
4895 <para>Parameterized.</para>
4900 <term>Parameter:</term>
4903 Keyword: <quote>block</quote>, or any user defined value.
4912 The keyword <quote>block</quote> will completely remove the header
4913 (not to be confused with the <literal><link linkend="block">block</link></literal>
4917 Alternately, you can specify any value you prefer to be sent to the web
4918 server. If you do, it is a matter of fairness not to use any address that
4919 is actually used by a real person.
4922 This action is rarely needed, as modern web browsers don't send
4923 <quote>From:</quote> headers anymore.
4929 <term>Example usage:</term>
4931 <screen>+hide-from-header{block}</screen>
4933 <screen>+hide-from-header{spam-me-senseless@sittingduck.example.com}</screen>
4940 <!-- ~~~~~ New section ~~~~~ -->
4941 <sect3 renderas="sect4" id="hide-referrer">
4942 <title>hide-referrer</title>
4943 <anchor id="hide-referer">
4946 <term>Typical use:</term>
4948 <para>Conceal which link you followed to get to a particular site</para>
4953 <term>Effect:</term>
4956 Deletes the <quote>Referer:</quote> (sic) HTTP header from the client request,
4957 or replaces it with a forged one.
4964 <!-- Boolean, Parameterized, Multi-value -->
4966 <para>Parameterized.</para>
4971 <term>Parameter:</term>
4975 <para><quote>conditional-block</quote> to delete the header completely if the host has changed.</para>
4978 <para><quote>conditional-forge</quote> to forge the header if the host has changed.</para>
4981 <para><quote>block</quote> to delete the header unconditionally.</para>
4984 <para><quote>forge</quote> to pretend to be coming from the homepage of the server we are talking to.</para>
4987 <para>Any other string to set a user defined referrer.</para>
4997 <literal>conditional-block</literal> is the only parameter,
4998 that isn't easily detected in the server's log file. If it blocks the
4999 referrer, the request will look like the visitor used a bookmark or
5000 typed in the address directly.
5003 Leaving the referrer unmodified for requests on the same host
5004 allows the server owner to see the visitor's <quote>click path</quote>,
5005 but in most cases she could also get that information by comparing
5006 other parts of the log file: for example the User-Agent if it isn't
5007 a very common one, or the user's IP address if it doesn't change between
5011 Always blocking the referrer, or using a custom one, can lead to
5012 failures on servers that check the referrer before they answer any
5013 requests, in an attempt to prevent their content from being
5014 embedded or linked to elsewhere.
5017 Both <literal>conditional-block</literal> and <literal>forge</literal>
5018 will work with referrer checks, as long as content and valid referring page
5019 are on the same host. Most of the time that's the case.
5022 <literal>hide-referer</literal> is an alternate spelling of
5023 <literal>hide-referrer</literal> and the two can be can be freely
5024 substituted with each other. (<quote>referrer</quote> is the
5025 correct English spelling, however the HTTP specification has a bug - it
5026 requires it to be spelled as <quote>referer</quote>.)
5032 <term>Example usage:</term>
5034 <screen>+hide-referrer{forge}</screen>
5036 <screen>+hide-referrer{http://www.yahoo.com/}</screen>
5043 <!-- ~~~~~ New section ~~~~~ -->
5044 <sect3 renderas="sect4" id="hide-user-agent">
5045 <title>hide-user-agent</title>
5049 <term>Typical use:</term>
5051 <para>Try to conceal your type of browser and client operating system</para>
5056 <term>Effect:</term>
5059 Replaces the value of the <quote>User-Agent:</quote> HTTP header
5060 in client requests with the specified value.
5067 <!-- Boolean, Parameterized, Multi-value -->
5069 <para>Parameterized.</para>
5074 <term>Parameter:</term>
5077 Any user-defined string.
5087 This can lead to problems on web sites that depend on looking at this header in
5088 order to customize their content for different browsers (which, by the
5089 way, is <emphasis>NOT</emphasis> the right thing to do: good web sites
5090 work browser-independently).
5094 Using this action in multi-user setups or wherever different types of
5095 browsers will access the same <application>Privoxy</application> is
5096 <emphasis>not recommended</emphasis>. In single-user, single-browser
5097 setups, you might use it to delete your OS version information from
5098 the headers, because it is an invitation to exploit known bugs for your
5099 OS. It is also occasionally useful to forge this in order to access
5100 sites that won't let you in otherwise (though there may be a good
5101 reason in some cases).
5104 More information on known user-agent strings can be found at
5105 <ulink url="http://www.user-agents.org/">http://www.user-agents.org/</ulink>
5107 <ulink url="https://en.wikipedia.org/wiki/User_agent">http://en.wikipedia.org/wiki/User_agent</ulink>.
5113 <term>Example usage:</term>
5115 <screen>+hide-user-agent{Mozilla/5.0 (X11; ElectroBSD i386; rv:78.0) Gecko/20100101 Firefox/78.0}</screen>
5122 <!-- ~~~~~ New section ~~~~~ -->
5123 <sect3 renderas="sect4" id="https-inspection">
5124 <title>https-inspection</title>
5128 <term>Typical use:</term>
5130 <para>Filter encrypted requests and responses</para>
5135 <term>Effect:</term>
5138 Encrypted requests are decrypted, filtered and forwarded encrypted.
5145 <!-- boolean, parameterized, Multi-value -->
5147 <para>Boolean.</para>
5152 <term>Parameter:</term>
5164 This action allows &my-app; to filter encrypted requests and responses.
5165 For this to work &my-app; has to generate a certificate and send it
5166 to the client which has to accept it.
5169 Before this works the directives in the
5170 <literal><ulink url="config.html#HTTPS-INSPECTION-DIRECTIVES">HTTPS inspection section</ulink></literal>
5171 of the config file have to be configured.
5174 Note that the action has to be enabled based on the CONNECT
5175 request which doesn't contain a path. Enabling it based on
5176 a pattern with path doesn't work as the path is only seen
5177 by &my-app; if the action is already enabled.
5180 This is an experimental feature.
5186 <term>Example usage (section):</term>
5188 <screen>{+https-inspection}
5189 www.example.com</screen>
5197 <!-- ~~~~~ New section ~~~~~ -->
5198 <sect3 renderas="sect4" id="ignore-certificate-errors">
5199 <title>ignore-certificate-errors</title>
5203 <term>Typical use:</term>
5205 <para>Filter encrypted requests and responses without verifying the certificate</para>
5210 <term>Effect:</term>
5213 Encrypted requests are forwarded to sites without verifying the certificate.
5220 <!-- Boolean, Parameterized, Multi-value -->
5222 <para>Boolean.</para>
5227 <term>Parameter:</term>
5240 <link linkend="HTTPS-INSPECTION"><quote>+https-inspection</quote></link>
5241 action is used &my-app; by default verifies that the remote site uses a valid
5245 If the certificate can't be validated by &my-app; the connection is aborted.
5248 This action disables the certificate check so requests to sites
5249 with certificates that can't be validated are allowed.
5252 Note that enabling this action allows Man-in-the-middle attacks.
5258 <term>Example usage:</term>
5261 {+ignore-certificate-errors}
5270 <!-- ~~~~~ New section ~~~~~ -->
5271 <sect3 renderas="sect4" id="limit-connect">
5272 <title>limit-connect</title>
5276 <term>Typical use:</term>
5278 <para>Prevent abuse of <application>Privoxy</application> as a TCP proxy relay or disable SSL for untrusted sites</para>
5283 <term>Effect:</term>
5286 Specifies to which ports HTTP CONNECT requests are allowable.
5293 <!-- Boolean, Parameterized, Multi-value -->
5295 <para>Parameterized.</para>
5300 <term>Parameter:</term>
5303 A comma-separated list of ports or port ranges (the latter using dashes, with the minimum
5304 defaulting to 0 and the maximum to 65K).
5313 By default, i.e. if no <literal>limit-connect</literal> action applies,
5314 <application>Privoxy</application> allows HTTP CONNECT requests to all
5315 ports. Use <literal>limit-connect</literal> if fine-grained control
5316 is desired for some or all destinations.
5319 The CONNECT methods exists in HTTP to allow access to secure websites
5320 (<quote>https://</quote> URLs) through proxies. It works very simply:
5321 the proxy connects to the server on the specified port, and then
5322 short-circuits its connections to the client and to the remote server.
5323 This means CONNECT-enabled proxies can be used as TCP relays very easily.
5326 <application>Privoxy</application> relays HTTPS traffic without seeing
5327 the decoded content. Websites can leverage this limitation to circumvent &my-app;'s
5328 filters. By specifying an invalid port range you can disable HTTPS entirely.
5334 <term>Example usages:</term>
5336 <!-- I had trouble getting the spacing to look right in my browser -->
5337 <!-- I probably have the wrong font setup, bollocks. -->
5338 <!-- Apparently the emphasis tag uses a proportional font no matter what -->
5339 <screen>+limit-connect{443} # Port 443 is OK.
5340 +limit-connect{80,443} # Ports 80 and 443 are OK.
5341 +limit-connect{-3, 7, 20-100, 500-} # Ports less than 3, 7, 20 to 100 and above 500 are OK.
5342 +limit-connect{-} # All ports are OK
5343 +limit-connect{,} # No HTTPS/SSL traffic is allowed</screen>
5350 <!-- ~~~~~ New section ~~~~~ -->
5351 <sect3 renderas="sect4" id="limit-cookie-lifetime">
5352 <title>limit-cookie-lifetime</title>
5356 <term>Typical use:</term>
5358 <para>Limit the lifetime of HTTP cookies to a couple of minutes or hours.</para>
5363 <term>Effect:</term>
5366 Overwrites the expires field in Set-Cookie server headers if it's above the specified limit.
5373 <!-- Boolean, Parameterized, Multi-value -->
5375 <para>Parameterized.</para>
5380 <term>Parameter:</term>
5383 The lifetime limit in minutes, or 0.
5392 This action reduces the lifetime of HTTP cookies coming from the
5393 server to the specified number of minutes, starting from the time
5394 the cookie passes Privoxy.
5397 Cookies with a lifetime below the limit are not modified.
5398 The lifetime of session cookies is set to the specified limit.
5401 The effect of this action depends on the server.
5404 In case of servers which refresh their cookies with each response
5405 (or at least frequently), the lifetime limit set by this action
5407 Thus, a session associated with the cookie continues to work with
5408 this action enabled, as long as a new request is made before the
5409 last limit set is reached.
5412 However, some servers send their cookies once, with a lifetime of several
5413 years (the year 2037 is a popular choice), and do not refresh them
5414 until a certain event in the future, for example the user logging out.
5415 In this case this action may limit the absolute lifetime of the session,
5416 even if requests are made frequently.
5419 If the parameter is <quote>0</quote>, this action behaves like
5420 <literal><link linkend="session-cookies-only">session-cookies-only</link></literal>.
5426 <term>Example usages:</term>
5428 <screen>+limit-cookie-lifetime{60}</screen>
5434 <!-- ~~~~~ New section ~~~~~ -->
5435 <sect3 renderas="sect4" id="prevent-compression">
5436 <title>prevent-compression</title>
5440 <term>Typical use:</term>
5443 Ensure that servers send the content uncompressed, so it can be
5444 passed through <literal><link linkend="filter">filter</link></literal>s.
5450 <term>Effect:</term>
5453 Removes the Accept-Encoding header which can be used to ask for compressed transfer.
5460 <!-- Boolean, Parameterized, Multi-value -->
5462 <para>Boolean.</para>
5467 <term>Parameter:</term>
5479 More and more websites send their content compressed by default, which
5480 is generally a good idea and saves bandwidth. But the <literal><link
5481 linkend="filter">filter</link></literal> and
5482 <literal><link linkend="deanimate-gifs">deanimate-gifs</link></literal>
5483 actions need access to the uncompressed data.
5486 When compiled with zlib support (available since &my-app; 3.0.7), content that should be
5487 filtered is decompressed on-the-fly and you don't have to worry about this action.
5488 If you are using an older &my-app; version, or one that hasn't been compiled with zlib
5489 support, this action can be used to convince the server to send the content uncompressed.
5492 Most text-based instances compress very well, the size is seldom decreased by less than 50%,
5493 for markup-heavy instances like news feeds saving more than 90% of the original size isn't
5497 Not using compression will therefore slow down the transfer, and you should only
5498 enable this action if you really need it. As of &my-app; 3.0.7 it's disabled in all
5499 predefined action settings.
5502 Note that some (rare) ill-configured sites don't handle requests for uncompressed
5503 documents correctly. Broken PHP applications tend to send an empty document body,
5504 some IIS versions only send the beginning of the content and some content delivery
5505 networks let the connection time out.
5506 If you enable <literal>prevent-compression</literal> per default, you might
5507 want to add exceptions for those sites. See the example for how to do that.
5513 <term>Example usage (sections):</term>
5516 # Selectively turn off compression, and enable a filter
5518 { +filter{tiny-textforms} +prevent-compression }
5519 # Match only these sites
5524 # Or instead, we could set a universal default:
5526 { +prevent-compression }
5529 # Then maybe make exceptions for broken sites:
5531 { -prevent-compression }
5532 .compusa.com/</screen>
5540 <!-- ~~~~~ New section ~~~~~ -->
5541 <sect3 renderas="sect4" id="overwrite-last-modified">
5542 <title>overwrite-last-modified</title>
5548 <term>Typical use:</term>
5550 <para>Prevent yet another way to track the user's steps between sessions.</para>
5555 <term>Effect:</term>
5558 Deletes the <quote>Last-Modified:</quote> HTTP server header or modifies its value.
5565 <!-- Boolean, Parameterized, Multi-value -->
5567 <para>Parameterized.</para>
5572 <term>Parameter:</term>
5575 One of the keywords: <quote>block</quote>, <quote>reset-to-request-time</quote>
5576 and <quote>randomize</quote>
5585 Removing the <quote>Last-Modified:</quote> header is useful for filter
5586 testing, where you want to force a real reload instead of getting status
5587 code <quote>304</quote>, which would cause the browser to reuse the old
5588 version of the page.
5591 The <quote>randomize</quote> option overwrites the value of the
5592 <quote>Last-Modified:</quote> header with a randomly chosen time
5593 between the original value and the current time. In theory the server
5594 could send each document with a different <quote>Last-Modified:</quote>
5595 header to track visits without using cookies. <quote>Randomize</quote>
5596 makes it impossible and the browser can still revalidate cached documents.
5599 <quote>reset-to-request-time</quote> overwrites the value of the
5600 <quote>Last-Modified:</quote> header with the current time. You could use
5601 this option together with
5602 <literal><link linkend="hide-if-modified-since">hide-if-modified-since</link></literal>
5603 to further customize your random range.
5606 The preferred parameter here is <quote>randomize</quote>. It is safe
5607 to use, as long as the time settings are more or less correct.
5608 If the server sets the <quote>Last-Modified:</quote> header to the time
5609 of the request, the random range becomes zero and the value stays the same.
5610 Therefore you should later randomize it a second time with
5611 <literal><link linkend="hide-if-modified-since">hided-if-modified-since</link></literal>,
5615 It is also recommended to use this action together with
5616 <literal><link linkend="crunch-if-none-match">crunch-if-none-match</link></literal>.
5622 <term>Example usage:</term>
5624 <screen># Let the browser revalidate without being tracked across sessions
5625 { +hide-if-modified-since{-60} \
5626 +overwrite-last-modified{randomize} \
5627 +crunch-if-none-match}
5635 <!-- ~~~~~ New section ~~~~~ -->
5636 <sect3 renderas="sect4" id="redirect">
5637 <title>redirect</title>
5643 <term>Typical use:</term>
5646 Redirect requests to other sites.
5652 <term>Effect:</term>
5655 Convinces the browser that the requested document has been moved
5656 to another location and the browser should get it from there.
5663 <!-- Boolean, Parameterized, Multi-value -->
5665 <para>Parameterized</para>
5670 <term>Parameter:</term>
5673 An absolute URL or a single pcrs command.
5682 Requests to which this action applies are answered with a
5683 HTTP redirect to URLs of your choosing. The new URL is
5684 either provided as parameter, or derived by applying a
5685 single pcrs command to the original URL.
5688 The syntax for pcrs commands is documented in the
5689 <link linkend="filter-file">filter file</link> section.
5692 Requests can't be blocked and redirected at the same time,
5693 applying this action together with
5694 <literal><link linkend="block">block</link></literal>
5695 is a configuration error. Currently the request is blocked
5696 and an error message logged, the behavior may change in the
5697 future and result in Privoxy rejecting the action file.
5700 This action can be combined with
5701 <literal><link linkend="fast-redirects">fast-redirects{check-decoded-url}</link></literal>
5702 to redirect to a decoded version of a rewritten URL.
5705 Use this action carefully, make sure not to create redirection loops
5706 and be aware that using your own redirects might make it
5707 possible to fingerprint your requests.
5710 In case of problems with your redirects, or simply to watch
5711 them working, enable <link linkend="DEBUG">debug 128</link>.
5717 <term>Example usages:</term>
5719 <screen># Replace example.com's style sheet with another one
5720 { +redirect{http://localhost/css-replacements/example.com.css} }
5721 example.com/stylesheet\.css
5723 # Create a short, easy to remember nickname for a favorite site
5724 # (relies on the browser to accept and forward invalid URLs to &my-app;)
5725 { +redirect{https://www.privoxy.org/user-manual/actions-file.html} }
5728 # Always use the expanded view for Undeadly.org articles
5729 # (Note the $ at the end of the URL pattern to make sure
5730 # the request for the rewritten URL isn't redirected as well)
5731 {+redirect{s@$@&mode=expanded@}}
5732 undeadly.org/cgi\?action=article&sid=\d*$
5734 # Redirect Google search requests to MSN
5735 {+redirect{s@^http://[^/]*/search\?q=([^&]*).*@http://search.msn.com/results.aspx?q=$1@}}
5738 # Redirect MSN search requests to Yahoo
5739 {+redirect{s@^http://[^/]*/results\.aspx\?q=([^&]*).*@http://search.yahoo.com/search?p=$1@}}
5740 search.msn.com//results\.aspx\?q=
5742 # Redirect http://example.com/&bla=fasel&toChange=foo (and any other value but "bar")
5743 # to http://example.com/&bla=fasel&toChange=bar
5745 # The URL pattern makes sure that the following request isn't redirected again.
5746 {+redirect{s@toChange=[^&]+@toChange=bar@}}
5747 example.com/.*toChange=(?!bar)
5749 # Add a shortcut to look up illumos bugs
5750 {+redirect{s@^http://i([0-9]+)/.*@https://www.illumos.org/issues/$1@}}
5751 # Redirected URL = http://i4974/
5752 # Redirect Destination = https://www.illumos.org/issues/4974
5753 i[0-9][0-9][0-9][0-9]*/
5755 # Redirect requests for the old Tor Hidden Service of the Privoxy website to the new one
5756 {+redirect{s@^http://jvauzb4sb3bwlsnc.onion/@http://l3tczdiiwoo63iwxty4lhs6p7eaxop5micbn7vbliydgv63x5zrrrfyd.onion/@}}
5757 jvauzb4sb3bwlsnc.onion/
5759 # Redirect remote requests for this manual
5760 # to the local version delivered by Privoxy
5761 {+redirect{s@^http://www@http://config@}}
5762 www.privoxy.org/user-manual/</screen>
5770 <!-- ~~~~~ New section ~~~~~ -->
5771 <sect3 renderas="sect4" id="server-header-filter">
5772 <title>server-header-filter</title>
5776 <term>Typical use:</term>
5779 Rewrite or remove single server headers.
5785 <term>Effect:</term>
5788 All server headers to which this action applies are filtered on-the-fly
5789 through the specified regular expression based substitutions.
5796 <!-- boolean, parameterized, Multi-value -->
5798 <para>Multi-value.</para>
5803 <term>Parameter:</term>
5806 The name of a server-header filter, as defined in one of the
5807 <link linkend="filter-file">filter files</link>.
5816 Server-header filters are applied to each header on its own, not to
5817 all at once. This makes it easier to diagnose problems, but on the downside
5818 you can't write filters that only change header x if header y's value is z.
5819 You can do that by using tags though.
5822 Server-header filters are executed after the other header actions have finished
5823 and use their output as input.
5826 Please refer to the <link linkend="filter-file">filter file chapter</link>
5827 to learn which server-header filters are available by default, and how to
5834 <term>Example usage (section):</term>
5837 {+server-header-filter{html-to-xml}}
5838 example.org/xml-instance-that-is-delivered-as-html
5840 {+server-header-filter{xml-to-html}}
5841 example.org/instance-that-is-delivered-as-xml-but-is-not
5850 <!-- ~~~~~ New section ~~~~~ -->
5851 <sect3 renderas="sect4" id="server-header-tagger">
5852 <title>server-header-tagger</title>
5856 <term>Typical use:</term>
5859 Enable or disable filters based on the Content-Type header.
5865 <term>Effect:</term>
5868 Server headers to which this action applies are filtered on-the-fly through
5869 the specified regular expression based substitutions, the result is used as
5877 <!-- boolean, parameterized, Multi-value -->
5879 <para>Multi-value.</para>
5884 <term>Parameter:</term>
5887 The name of a server-header tagger, as defined in one of the
5888 <link linkend="filter-file">filter files</link>.
5897 Server-header taggers are applied to each header on its own,
5898 and as the header isn't modified, each tagger <quote>sees</quote>
5902 Server-header taggers are executed before all other header actions
5903 that modify server headers. Their tags can be used to control
5904 all of the other server-header actions, the content filters
5905 and the crunch actions (<link linkend="redirect">redirect</link>
5906 and <link linkend="block">block</link>).
5909 Obviously crunching based on tags created by server-header taggers
5910 doesn't prevent the request from showing up in the server's log file.
5917 <term>Example usage (section):</term>
5920 # Tag every request with the content type declared by the server
5921 {+server-header-tagger{content-type}}
5924 # If the response has a tag starting with 'image/' enable an external
5925 # filter that only applies to images.
5927 # Note that the filter is not available by default, it's just a
5928 # <literal><link linkend="external-filter-syntax">silly example</link></literal>.
5929 {+external-filter{rotate-image} +force-text-mode}
5939 <!-- ~~~~~ New section ~~~~~ -->
5940 <sect3 renderas="sect4" id="suppress-tag">
5941 <title>suppress-tag</title>
5945 <term>Typical use:</term>
5948 Suppress client or server tag.
5954 <term>Effect:</term>
5957 Server or client tags to which this action applies are not added to the request,
5958 thus making all actions that are specific to these request tags inactive.
5965 <!-- boolean, parameterized, Multi-value -->
5967 <para>Multi-value.</para>
5972 <term>Parameter:</term>
5975 The result tag of a server-header or client-header tagger, as defined in one of the
5976 <link linkend="filter-file">filter files</link>.
5982 <term>Example usage (section):</term>
5985 # Suppress tag produced by range-requests client-header tagger for requests coming from address 10.0.0.1
5986 {+suppress-tag{RANGE-REQUEST}}
5987 TAG:^IP-ADDRESS: 10\.0\.0\.1$
5996 <!-- ~~~~~ New section ~~~~~ -->
5997 <sect3 renderas="sect4" id="session-cookies-only">
5998 <title>session-cookies-only</title>
6002 <term>Typical use:</term>
6005 Allow only temporary <quote>session</quote> cookies (for the current
6006 browser session <emphasis>only</emphasis>).
6012 <term>Effect:</term>
6015 Deletes the <quote>expires</quote> field from <quote>Set-Cookie:</quote>
6016 server headers. Most browsers will not store such cookies permanently and
6017 forget them in between sessions.
6024 <!-- Boolean, Parameterized, Multi-value -->
6026 <para>Boolean.</para>
6031 <term>Parameter:</term>
6043 This is less strict than <literal><link linkend="crunch-incoming-cookies">crunch-incoming-cookies</link></literal> /
6044 <literal><link linkend="crunch-outgoing-cookies">crunch-outgoing-cookies</link></literal> and allows you to browse
6045 websites that insist or rely on setting cookies, without compromising your privacy too badly.
6048 Most browsers will not permanently store cookies that have been processed by
6049 <literal>session-cookies-only</literal> and will forget about them between sessions.
6050 This makes profiling cookies useless, but won't break sites which require cookies so
6051 that you can log in for transactions. This is generally turned on for all
6052 sites, and is the recommended setting.
6055 It makes <emphasis>no sense at all</emphasis> to use <literal>session-cookies-only</literal>
6056 together with <literal><link linkend="crunch-incoming-cookies">crunch-incoming-cookies</link></literal> or
6057 <literal><link linkend="crunch-outgoing-cookies">crunch-outgoing-cookies</link></literal>. If you do, cookies
6058 will be plainly killed.
6061 Note that it is up to the browser how it handles such cookies without an <quote>expires</quote>
6062 field. If you use an exotic browser, you might want to try it out to be sure.
6065 This setting also has no effect on cookies that may have been stored
6066 previously by the browser before starting <application>Privoxy</application>.
6067 These would have to be removed manually.
6070 <application>Privoxy</application> also uses
6071 the <link linkend="filter-content-cookies">content-cookies filter</link>
6072 to block some types of cookies. Content cookies are not effected by
6073 <literal>session-cookies-only</literal>.
6079 <term>Example usage:</term>
6081 <screen>+session-cookies-only</screen>
6088 <!-- ~~~~~ New section ~~~~~ -->
6089 <sect3 renderas="sect4" id="set-image-blocker">
6090 <title>set-image-blocker</title>
6094 <term>Typical use:</term>
6096 <para>Choose the replacement for blocked images</para>
6101 <term>Effect:</term>
6104 This action alone doesn't do anything noticeable. If <emphasis>both</emphasis>
6105 <literal><link linkend="block">block</link></literal> <emphasis>and</emphasis> <literal><link
6106 linkend="handle-as-image">handle-as-image</link></literal> <emphasis>also</emphasis>
6107 apply, i.e. if the request is to be blocked as an image,
6108 <emphasis>then</emphasis> the parameter of this action decides what will be
6109 sent as a replacement.
6116 <!-- Boolean, Parameterized, Multi-value -->
6118 <para>Parameterized.</para>
6123 <term>Parameter:</term>
6128 <quote>pattern</quote> to send a built-in checkerboard pattern image. The image is visually
6129 decent, scales very well, and makes it obvious where banners were busted.
6134 <quote>blank</quote> to send a built-in transparent image. This makes banners disappear
6135 completely, but makes it hard to detect where <application>Privoxy</application> has blocked
6136 images on a given page and complicates troubleshooting if <application>Privoxy</application>
6137 has blocked innocent images, like navigation icons.
6142 <quote><replaceable class="parameter">target-url</replaceable></quote> to
6143 send a redirect to <replaceable class="parameter">target-url</replaceable>. You can redirect
6144 to any image anywhere, even in your local filesystem via <quote>file:///</quote> URL.
6145 (But note that not all browsers support redirecting to a local file system).
6148 A good application of redirects is to use special <application>Privoxy</application>-built-in
6149 URLs, which send the built-in images, as <replaceable class="parameter">target-url</replaceable>.
6150 This has the same visual effect as specifying <quote>blank</quote> or <quote>pattern</quote> in
6151 the first place, but enables your browser to cache the replacement image, instead of requesting
6152 it over and over again.
6163 The URLs for the built-in images are <quote>http://config.privoxy.org/send-banner?type=<replaceable
6164 class="parameter">type</replaceable></quote>, where <replaceable class="parameter">type</replaceable> is
6165 either <quote>blank</quote> or <quote>pattern</quote>.
6168 There is a third (advanced) type, called <quote>auto</quote>. It is <emphasis>NOT</emphasis> to be
6169 used in <literal>set-image-blocker</literal>, but meant for use from <link linkend="filter-file">filters</link>.
6170 Auto will select the type of image that would have applied to the referring page, had it been an image.
6176 <term>Example usage:</term>
6181 <screen>+set-image-blocker{pattern}</screen>
6183 Redirect to the BSD daemon:
6185 <screen>+set-image-blocker{http://www.freebsd.org/gifs/dae_up3.gif}</screen>
6187 Redirect to the built-in pattern for better caching:
6189 <screen>+set-image-blocker{http://config.privoxy.org/send-banner?type=pattern}</screen>
6196 <!-- ~~~~~ New section ~~~~~ -->
6197 <sect3 id="summary">
6198 <title>Summary</title>
6200 Note that many of these actions have the potential to cause a page to
6201 misbehave, possibly even not to display at all. There are many ways
6202 a site designer may choose to design his site, and what HTTP header
6203 content, and other criteria, he may depend on. There is no way to have hard
6204 and fast rules for all sites. See the <link
6205 linkend="ACTIONSANAT">Appendix</link> for a brief example on troubleshooting
6211 <!-- ~~~~~ New section ~~~~~ -->
6212 <sect2 id="aliases">
6213 <title>Aliases</title>
6215 Custom <quote>actions</quote>, known to <application>Privoxy</application>
6216 as <quote>aliases</quote>, can be defined by combining other actions.
6217 These can in turn be invoked just like the built-in actions.
6218 Currently, an alias name can contain any character except space, tab,
6220 <quote>{</quote> and <quote>}</quote>, but we <emphasis>strongly
6221 recommend</emphasis> that you only use <quote>a</quote> to <quote>z</quote>,
6222 <quote>0</quote> to <quote>9</quote>, <quote>+</quote>, and <quote>-</quote>.
6223 Alias names are not case sensitive, and are not required to start with a
6224 <quote>+</quote> or <quote>-</quote> sign, since they are merely textually
6228 Aliases can be used throughout the actions file, but they <emphasis>must be
6229 defined in a special section at the top of the file!</emphasis>
6230 And there can only be one such section per actions file. Each actions file may
6231 have its own alias section, and the aliases defined in it are only visible
6235 There are two main reasons to use aliases: One is to save typing for frequently
6236 used combinations of actions, the other one is a gain in flexibility: If you
6237 decide once how you want to handle shops by defining an alias called
6238 <quote>shop</quote>, you can later change your policy on shops in
6239 <emphasis>one</emphasis> place, and your changes will take effect everywhere
6240 in the actions file where the <quote>shop</quote> alias is used. Calling aliases
6241 by their purpose also makes your actions files more readable.
6244 Currently, there is one big drawback to using aliases, though:
6245 <application>Privoxy</application>'s built-in web-based action file
6246 editor honors aliases when reading the actions files, but it expands
6247 them before writing. So the effects of your aliases are of course preserved,
6248 but the aliases themselves are lost when you edit sections that use aliases
6253 Now let's define some aliases...
6257 # Useful custom aliases we can use later.
6259 # Note the (required!) section header line and that this section
6260 # must be at the top of the actions file!
6264 # These aliases just save typing later:
6265 # (Note that some already use other aliases!)
6267 +crunch-all-cookies = +<link linkend="CRUNCH-INCOMING-COOKIES">crunch-incoming-cookies</link> +<link linkend="CRUNCH-OUTGOING-COOKIES">crunch-outgoing-cookies</link>
6268 -crunch-all-cookies = -<link linkend="CRUNCH-INCOMING-COOKIES">crunch-incoming-cookies</link> -<link linkend="CRUNCH-OUTGOING-COOKIES">crunch-outgoing-cookies</link>
6269 +block-as-image = +block{Blocked image.} +handle-as-image
6270 allow-all-cookies = -crunch-all-cookies -<link linkend="SESSION-COOKIES-ONLY">session-cookies-only</link> -<link linkend="FILTER-CONTENT-COOKIES">filter{content-cookies}</link>
6272 # These aliases define combinations of actions
6273 # that are useful for certain types of sites:
6275 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>
6277 shop = -crunch-all-cookies -<link linkend="FILTER-ALL-POPUPS">filter{all-popups}</link>
6279 # Short names for other aliases, for really lazy people ;-)
6281 c0 = +crunch-all-cookies
6282 c1 = -crunch-all-cookies</screen>
6285 ...and put them to use. These sections would appear in the lower part of an
6286 actions file and define exceptions to the default actions (as specified further
6287 up for the <quote>/</quote> pattern):
6291 # These sites are either very complex or very keen on
6292 # user data and require minimal interference to work:
6295 .office.microsoft.com
6296 .windowsupdate.microsoft.com
6297 # Gmail is really mail.google.com, not gmail.com
6301 # Allow cookies (for setting and retrieving your customer data)
6305 .worldpay.com # for quietpc.com
6308 # These shops require pop-ups:
6310 {-filter{all-popups} -filter{unsolicited-popups}}
6312 .overclockers.co.uk</screen>
6315 Aliases like <quote>shop</quote> and <quote>fragile</quote> are typically used for
6316 <quote>problem</quote> sites that require more than one action to be disabled
6317 in order to function properly.
6323 <!-- ~~~~~ New section ~~~~~ -->
6324 <sect2 id="act-examples">
6325 <title>Actions Files Tutorial</title>
6327 The above chapters have shown <link linkend="actions-file">which actions files
6328 there are and how they are organized</link>, how actions are <link
6329 linkend="actions">specified</link> and <link linkend="actions-apply">applied
6330 to URLs</link>, how <link linkend="af-patterns">patterns</link> work, and how to
6331 define and use <link linkend="aliases">aliases</link>. Now, let's look at an
6332 example <filename>match-all.action</filename>, <filename>default.action</filename>
6333 and <filename>user.action</filename> file and see how all these pieces come together:
6336 <sect3 id="match-all">
6337 <title>match-all.action</title>
6339 Remember <emphasis>all actions are disabled when matching starts</emphasis>,
6340 so we have to explicitly enable the ones we want.
6344 While the <filename>match-all.action</filename> file only contains a
6345 single section, it is probably the most important one. It has only one
6346 pattern, <quote><literal>/</literal></quote>, but this pattern
6347 <link linkend="af-patterns">matches all URLs</link>. Therefore, the set of
6348 actions used in this <quote>default</quote> section <emphasis>will
6349 be applied to all requests as a start</emphasis>. It can be partly or
6350 wholly overridden by other actions files like <filename>default.action</filename>
6351 and <filename>user.action</filename>, but it will still be largely responsible
6352 for your overall browsing experience.
6356 Again, at the start of matching, all actions are disabled, so there is
6357 no need to disable any actions here. (Remember: a <quote>+</quote>
6358 preceding the action name enables the action, a <quote>-</quote> disables!).
6359 Also note how this long line has been made more readable by splitting it into
6360 multiple lines with line continuation.
6365 +<link linkend="CHANGE-X-FORWARDED-FOR">change-x-forwarded-for{block}</link> \
6366 +<link linkend="HIDE-FROM-HEADER">hide-from-header{block}</link> \
6367 +<link linkend="SET-IMAGE-BLOCKER">set-image-blocker{pattern}</link> \
6373 The default behavior is now set.
6377 <sect3 id="default-action">
6378 <title>default.action</title>
6381 If you aren't a developer, there's no need for you to edit the
6382 <filename>default.action</filename> file. It is maintained by
6383 the &my-app; developers and if you disagree with some of the
6384 sections, you should overrule them in your <filename>user.action</filename>.
6388 Understanding the <filename>default.action</filename> file can
6389 help you with your <filename>user.action</filename>, though.
6393 The first section in this file is a special section for internal use
6394 that prevents older &my-app; versions from reading the file:
6398 ##########################################################################
6399 # Settings -- Don't change! For internal Privoxy use ONLY.
6400 ##########################################################################
6402 for-privoxy-version=3.0.11</screen>
6405 After that comes the (optional) alias section. We'll use the example
6406 section from the above <link linkend="aliases">chapter on aliases</link>,
6407 that also explains why and how aliases are used:
6411 ##########################################################################
6413 ##########################################################################
6416 # These aliases just save typing later:
6417 # (Note that some already use other aliases!)
6419 +crunch-all-cookies = +<link linkend="CRUNCH-INCOMING-COOKIES">crunch-incoming-cookies</link> +<link linkend="CRUNCH-OUTGOING-COOKIES">crunch-outgoing-cookies</link>
6420 -crunch-all-cookies = -<link linkend="CRUNCH-INCOMING-COOKIES">crunch-incoming-cookies</link> -<link linkend="CRUNCH-OUTGOING-COOKIES">crunch-outgoing-cookies</link>
6421 +block-as-image = +block{Blocked image.} +handle-as-image
6422 mercy-for-cookies = -crunch-all-cookies -<link linkend="SESSION-COOKIES-ONLY">session-cookies-only</link> -<link linkend="FILTER-CONTENT-COOKIES">filter{content-cookies}</link>
6424 # These aliases define combinations of actions
6425 # that are useful for certain types of sites:
6427 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>
6428 shop = -crunch-all-cookies -<link linkend="FILTER-ALL-POPUPS">filter{all-popups}</link></screen>
6431 The first of our specialized sections is concerned with <quote>fragile</quote>
6432 sites, i.e. sites that require minimum interference, because they are either
6433 very complex or very keen on tracking you (and have mechanisms in place that
6434 make them unusable for people who avoid being tracked). We will use
6435 our pre-defined <literal>fragile</literal> alias instead of stating the list
6436 of actions explicitly:
6440 ##########################################################################
6441 # Exceptions for sites that'll break under the default action set:
6442 ##########################################################################
6444 # "Fragile" Use a minimum set of actions for these sites (see alias above):
6447 .office.microsoft.com # surprise, surprise!
6448 .windowsupdate.microsoft.com
6449 mail.google.com</screen>
6452 Shopping sites are not as fragile, but they typically
6453 require cookies to log in, and pop-up windows for shopping
6454 carts or item details. Again, we'll use a pre-defined alias:
6462 .worldpay.com # for quietpc.com
6464 .scan.co.uk</screen>
6467 The <literal><link linkend="FAST-REDIRECTS">fast-redirects</link></literal>
6468 action, which may have been enabled in <filename>match-all.action</filename>,
6469 breaks some sites. So disable it for popular sites where we know it misbehaves:
6473 { -<link linkend="FAST-REDIRECTS">fast-redirects</link> }
6477 .altavista.com/.*(like|url|link):http
6478 .altavista.com/trans.*urltext=http
6479 .nytimes.com</screen>
6482 It is important that <application>Privoxy</application> knows which
6483 URLs belong to images, so that <emphasis>if</emphasis> they are to
6484 be blocked, a substitute image can be sent, rather than an HTML page.
6485 Contacting the remote site to find out is not an option, since it
6486 would destroy the loading time advantage of banner blocking, and it
6487 would feed the advertisers information about you. We can mark any
6488 URL as an image with the <literal><link
6489 linkend="handle-as-image">handle-as-image</link></literal> action,
6490 and marking all URLs that end in a known image file extension is a
6495 ##########################################################################
6497 ##########################################################################
6499 # Define which file types will be treated as images, in case they get
6500 # blocked further down this file:
6502 { +<link linkend="HANDLE-AS-IMAGE">handle-as-image</link> }
6503 /.*\.(gif|jpe?g|png|bmp|ico)$</screen>
6506 And then there are known banner sources. They often use scripts to
6507 generate the banners, so it won't be visible from the URL that the
6508 request is for an image. Hence we block them <emphasis>and</emphasis>
6509 mark them as images in one go, with the help of our
6510 <literal>+block-as-image</literal> alias defined above. (We could of
6511 course just as well use <literal>+<link linkend="block">block</link>
6512 +<link linkend="handle-as-image">handle-as-image</link></literal> here.)
6513 Remember that the type of the replacement image is chosen by the
6514 <literal><link linkend="set-image-blocker">set-image-blocker</link></literal>
6515 action. Since all URLs have matched the default section with its
6516 <literal>+<link linkend="set-image-blocker">set-image-blocker</link>{pattern}</literal>
6517 action before, it still applies and needn't be repeated:
6521 # Known ad generators:
6526 .ad.*.doubleclick.net
6527 .a.yimg.com/(?:(?!/i/).)*$
6528 .a[0-9].yimg.com/(?:(?!/i/).)*$
6533 One of the most important jobs of <application>Privoxy</application>
6534 is to block banners. Many of these can be <quote>blocked</quote>
6535 by the <literal><link linkend="filter">filter</link>{banners-by-size}</literal>
6536 action, which we enabled above, and which deletes the references to banner
6537 images from the pages while they are loaded, so the browser doesn't request
6538 them anymore, and hence they don't need to be blocked here. But this naturally
6539 doesn't catch all banners, and some people choose not to use filters, so we
6540 need a comprehensive list of patterns for banner URLs here, and apply the
6541 <literal><link linkend="block">block</link></literal> action to them.
6544 First comes many generic patterns, which do most of the work, by
6545 matching typical domain and path name components of banners. Then comes
6546 a list of individual patterns for specific sites, which is omitted here
6547 to keep the example short:
6551 ##########################################################################
6552 # Block these fine banners:
6553 ##########################################################################
6554 { <link linkend="BLOCK">+block{Banner ads.}</link> }
6562 /.*count(er)?\.(pl|cgi|exe|dll|asp|php[34]?)
6563 /(?:.*/)?(publicite|werbung|rekla(ma|me|am)|annonse|maino(kset|nta|s)?)/
6565 # Site-specific patterns (abbreviated):
6567 .hitbox.com</screen>
6570 It's quite remarkable how many advertisers actually call their banner
6571 servers ads.<replaceable>company</replaceable>.com, or call the directory
6572 in which the banners are stored literally <quote>banners</quote>. So the above
6573 generic patterns are surprisingly effective.
6576 But being very generic, they necessarily also catch URLs that we don't want
6577 to block. The pattern <literal>.*ads.</literal> e.g. catches
6578 <quote>nasty-<emphasis>ads</emphasis>.nasty-corp.com</quote> as intended,
6579 but also <quote>downlo<emphasis>ads</emphasis>.sourcefroge.net</quote> or
6580 <quote><emphasis>ads</emphasis>l.some-provider.net.</quote> So here come some
6581 well-known exceptions to the <literal>+<link linkend="BLOCK">block</link></literal>
6585 Note that these are exceptions to exceptions from the default! Consider the URL
6586 <quote>downloads.sourcefroge.net</quote>: Initially, all actions are deactivated,
6587 so it wouldn't get blocked. Then comes the defaults section, which matches the
6588 URL, but just deactivates the <literal><link linkend="BLOCK">block</link></literal>
6589 action once again. Then it matches <literal>.*ads.</literal>, an exception to the
6590 general non-blocking policy, and suddenly
6591 <literal><link linkend="BLOCK">+block</link></literal> applies. And now, it'll match
6592 <literal>.*loads.</literal>, where <literal><link linkend="BLOCK">-block</link></literal>
6593 applies, so (unless it matches <emphasis>again</emphasis> further down) it ends up
6594 with no <literal><link linkend="BLOCK">block</link></literal> action applying.
6598 ##########################################################################
6599 # Save some innocent victims of the above generic block patterns:
6600 ##########################################################################
6604 { -<link linkend="BLOCK">block</link> }
6605 adv[io]*. # (for advogato.org and advice.*)
6606 adsl. # (has nothing to do with ads)
6607 adobe. # (has nothing to do with ads either)
6608 ad[ud]*. # (adult.* and add.*)
6609 .edu # (universities don't host banners (yet!))
6610 .*loads. # (downloads, uploads etc)
6618 www.globalintersec.com/adv # (adv = advanced)
6619 www.ugu.com/sui/ugu/adv</screen>
6622 Filtering source code can have nasty side effects,
6623 so make an exception for our friends at sourceforge.net,
6624 and all paths with <quote>cvs</quote> in them. Note that
6625 <literal>-<link linkend="FILTER">filter</link></literal>
6626 disables <emphasis>all</emphasis> filters in one fell swoop!
6630 # Don't filter code!
6632 { -<link linkend="FILTER">filter</link> }
6637 .sourceforge.net</screen>
6640 The actual <filename>default.action</filename> is of course much more
6641 comprehensive, but we hope this example made clear how it works.
6646 <sect3 id="user-action"><title>user.action</title>
6649 So far we are painting with a broad brush by setting general policies,
6650 which would be a reasonable starting point for many people. Now,
6651 you might want to be more specific and have customized rules that
6652 are more suitable to your personal habits and preferences. These would
6653 be for narrowly defined situations like your ISP or your bank, and should
6654 be placed in <filename>user.action</filename>, which is parsed after all other
6655 actions files and hence has the last word, over-riding any previously
6656 defined actions. <filename>user.action</filename> is also a
6657 <emphasis>safe</emphasis> place for your personal settings, since
6658 <filename>default.action</filename> is actively maintained by the
6659 <application>Privoxy</application> developers and you'll probably want
6660 to install updated versions from time to time.
6664 So let's look at a few examples of things that one might typically do in
6665 <filename>user.action</filename>:
6669 <!-- brief sample user.action here -->
6672 # My user.action file. <fred@example.com></screen>
6675 As <link linkend="aliases">aliases</link> are local to the actions
6676 file that they are defined in, you can't use the ones from
6677 <filename>default.action</filename>, unless you repeat them here:
6681 # Aliases are local to the file they are defined in.
6682 # (Re-)define aliases for this file:
6686 # These aliases just save typing later, and the alias names should
6687 # be self explanatory.
6689 +crunch-all-cookies = +crunch-incoming-cookies +crunch-outgoing-cookies
6690 -crunch-all-cookies = -crunch-incoming-cookies -crunch-outgoing-cookies
6691 allow-all-cookies = -crunch-all-cookies -session-cookies-only
6692 allow-popups = -filter{all-popups}
6693 +block-as-image = +block{Blocked as image.} +handle-as-image
6694 -block-as-image = -block
6696 # These aliases define combinations of actions that are useful for
6697 # certain types of sites:
6699 fragile = -block -crunch-all-cookies -filter -fast-redirects -hide-referrer
6700 shop = -crunch-all-cookies allow-popups
6702 # Allow ads for selected useful free sites:
6704 allow-ads = -block -filter{banners-by-size} -filter{banners-by-link}
6706 # Alias for specific file types that are text, but might have conflicting
6707 # MIME types. We want the browser to force these to be text documents.
6708 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>
6711 Say you have accounts on some sites that you visit regularly, and
6712 you don't want to have to log in manually each time. So you'd like
6713 to allow persistent cookies for these sites. The
6714 <literal>allow-all-cookies</literal> alias defined above does exactly
6715 that, i.e. it disables crunching of cookies in any direction, and the
6716 processing of cookies to make them only temporary.
6720 { allow-all-cookies }
6724 .redhat.com</screen>
6727 Your bank is allergic to some filter, but you don't know which, so you disable them all:
6731 { -<link linkend="FILTER">filter</link> }
6732 .your-home-banking-site.com</screen>
6735 Some file types you may not want to filter for various reasons:
6739 # Technical documentation is likely to contain strings that might
6740 # erroneously get altered by the JavaScript-oriented filters:
6745 # And this stupid host sends streaming video with a wrong MIME type,
6746 # so that Privoxy thinks it is getting HTML and starts filtering:
6748 stupid-server.example.com/</screen>
6751 Example of a simple <link linkend="BLOCK">block</link> action. Say you've
6752 seen an ad on your favourite page on example.com that you want to get rid of.
6753 You have right-clicked the image, selected <quote>copy image location</quote>
6754 and pasted the URL below while removing the leading http://, into a
6755 <literal>{ +block{} }</literal> section. Note that <literal>{ +handle-as-image
6756 }</literal> need not be specified, since all URLs ending in
6757 <literal>.gif</literal> will be tagged as images by the general rules as set
6758 in default.action anyway:
6762 { +<link linkend="BLOCK">block</link>{Nasty ads.} }
6763 www.example.com/nasty-ads/sponsor\.gif
6764 another.example.net/more/junk/here/</screen>
6767 The URLs of dynamically generated banners, especially from large banner
6768 farms, often don't use the well-known image file name extensions, which
6769 makes it impossible for <application>Privoxy</application> to guess
6770 the file type just by looking at the URL.
6771 You can use the <literal>+block-as-image</literal> alias defined above for
6773 Note that objects which match this rule but then turn out NOT to be an
6774 image are typically rendered as a <quote>broken image</quote> icon by the
6775 browser. Use cautiously.
6783 ar.atwola.com/</screen>
6786 Now you noticed that the default configuration breaks Forbes Magazine,
6787 but you were too lazy to find out which action is the culprit, and you
6788 were again too lazy to give <link linkend="contact">feedback</link>, so
6789 you just used the <literal>fragile</literal> alias on the site, and
6790 -- <emphasis>whoa!</emphasis> -- it worked. The <literal>fragile</literal>
6791 aliases disables those actions that are most likely to break a site. Also,
6792 good for testing purposes to see if it is <application>Privoxy</application>
6793 that is causing the problem or not. We later find other regular sites
6794 that misbehave, and add those to our personalized list of troublemakers:
6801 .mybank.com</screen>
6804 You like the <quote>fun</quote> text replacements in <filename>default.filter</filename>,
6805 but it is disabled in the distributed actions file.
6806 So you'd like to turn it on in your private,
6807 update-safe config, once and for all:
6811 { +<link linkend="filter-fun">filter{fun}</link> }
6812 / # For ALL sites!</screen>
6815 Note that the above is not really a good idea: There are exceptions
6816 to the filters in <filename>default.action</filename> for things that
6817 really shouldn't be filtered, like code on CVS->Web interfaces. Since
6818 <filename>user.action</filename> has the last word, these exceptions
6819 won't be valid for the <quote>fun</quote> filtering specified here.
6823 You might also worry about how your favourite free websites are
6824 funded, and find that they rely on displaying banner advertisements
6825 to survive. So you might want to specifically allow banners for those
6826 sites that you feel provide value to you:
6836 Note that <literal>allow-ads</literal> has been aliased to
6837 <literal>-<link linkend="block">block</link></literal>,
6838 <literal>-<link linkend="filter-banners-by-size">filter{banners-by-size}</link></literal>, and
6839 <literal>-<link linkend="filter-banners-by-link">filter{banners-by-link}</link></literal> above.
6843 Invoke another alias here to force an over-ride of the MIME type <literal>
6844 application/x-sh</literal> which typically would open a download type
6845 dialog. In my case, I want to look at the shell script, and then I can save
6846 it should I choose to.
6854 <filename>user.action</filename> is generally the best place to define
6855 exceptions and additions to the default policies of
6856 <filename>default.action</filename>. Some actions are safe to have their
6857 default policies set here though. So let's set a default policy to have a
6858 <quote>blank</quote> image as opposed to the checkerboard pattern for
6859 <emphasis>ALL</emphasis> sites. <quote>/</quote> of course matches all URL
6864 { +<link linkend="set-image-blocker">set-image-blocker{blank}</link> }
6865 / # ALL sites</screen>
6870 <!-- ~ End section ~ -->
6874 <!-- ~ End section ~ -->
6876 <!-- ~~~~~~~~ New section Header ~~~~~~~~~ -->
6878 <sect1 id="filter-file">
6879 <title>Filter Files</title>
6882 On-the-fly text substitutions need
6883 to be defined in a <quote>filter file</quote>. Once defined, they
6884 can then be invoked as an <quote>action</quote>.
6888 &my-app; supports three different pcrs-based filter actions:
6889 <literal><link linkend="filter">filter</link></literal> to
6890 rewrite the content that is send to the client,
6891 <literal><link linkend="client-header-filter">client-header-filter</link></literal>
6892 to rewrite headers that are send by the client, and
6893 <literal><link linkend="server-header-filter">server-header-filter</link></literal>
6894 to rewrite headers that are send by the server.
6898 &my-app; also supports two tagger actions:
6899 <literal><link linkend="client-header-tagger">client-header-tagger</link></literal>
6901 <literal><link linkend="server-header-tagger">server-header-tagger</link></literal>.
6902 Taggers and filters use the same syntax in the filter files, the difference
6903 is that taggers don't modify the text they are filtering, but use a rewritten
6904 version of the filtered text as tag. The tags can then be used to change the
6905 applying actions through sections with <link linkend="tag-pattern">tag-patterns</link>.
6909 Finally &my-app; supports the
6910 <literal><link linkend="external-filter">external-filter</link></literal> action
6911 to enable <literal><link linkend="external-filter-syntax">external filters</link></literal>
6912 written in proper programming languages.
6917 Multiple filter files can be defined through the <literal> <link
6918 linkend="filterfile">filterfile</link></literal> config directive. The filters
6919 as supplied by the developers are located in
6920 <filename>default.filter</filename>. It is recommended that any locally
6921 defined or modified filters go in a separately defined file such as
6922 <filename>user.filter</filename>.
6926 Common tasks for content filters are to eliminate common annoyances in
6927 HTML and JavaScript, such as pop-up windows,
6928 exit consoles, crippled windows without navigation tools, the
6929 infamous <BLINK> tag etc, to suppress images with certain
6930 width and height attributes (standard banner sizes or web-bugs),
6931 or just to have fun.
6935 Enabled content filters are applied to any content whose
6936 <quote>Content Type</quote> header is recognised as a sign
6937 of text-based content, with the exception of <literal>text/plain</literal>.
6938 Use the <link linkend="FORCE-TEXT-MODE">force-text-mode</link> action
6939 to also filter other content.
6943 Substitutions are made at the source level, so if you want to <quote>roll
6944 your own</quote> filters, you should first be familiar with HTML syntax,
6945 and, of course, regular expressions.
6949 Just like the <link linkend="actions-file">actions files</link>, the
6950 filter file is organized in sections, which are called <emphasis>filters</emphasis>
6951 here. Each filter consists of a heading line, that starts with one of the
6952 <emphasis>keywords</emphasis> <literal>FILTER:</literal>,
6953 <literal>CLIENT-HEADER-FILTER:</literal> or <literal>SERVER-HEADER-FILTER:</literal>
6954 followed by the filter's <emphasis>name</emphasis>, and a short (one line)
6955 <emphasis>description</emphasis> of what it does. Below that line
6956 come the <emphasis>jobs</emphasis>, i.e. lines that define the actual
6957 text substitutions. By convention, the name of a filter
6958 should describe what the filter <emphasis>eliminates</emphasis>. The
6959 comment is used in the <ulink url="http://config.privoxy.org/">web-based
6960 user interface</ulink>.
6964 Once a filter called <replaceable>name</replaceable> has been defined
6965 in the filter file, it can be invoked by using an action of the form
6966 +<literal><link linkend="filter">filter</link>{<replaceable>name</replaceable>}</literal>
6967 in any <link linkend="actions-file">actions file</link>.
6971 Filter definitions start with a header line that contains the filter
6972 type, the filter name and the filter description.
6973 A content filter header line for a filter called <quote>foo</quote> could look
6977 <screen>FILTER: foo Replace all "foo" with "bar"</screen>
6980 Below that line, and up to the next header line, come the jobs that
6981 define what text replacements the filter executes. They are specified
6982 in a syntax that imitates <ulink url="http://www.perl.org/">Perl</ulink>'s
6983 <literal>s///</literal> operator. If you are familiar with Perl, you
6984 will find this to be quite intuitive, and may want to look at the
6985 PCRS documentation for the subtle differences to Perl behaviour.
6989 Most notably, the non-standard option letter <literal>U</literal> is supported,
6990 which turns the default to ungreedy matching (add <literal>?</literal> to
6991 quantifiers to turn them greedy again).
6995 The non-standard option letter <literal>D</literal> (dynamic) allows
6996 to use the variables $host, $origin (the IP address the request came from),
6997 $path, $url and $listen-address (the address on which Privoxy accepted the
6998 client request. Example: 127.0.0.1:8118).
6999 They will be replaced with the value they refer to before the filter
7004 Note that '$' is a bad choice for a delimiter in a dynamic filter as you
7005 might end up with unintended variables if you use a variable name
7006 directly after the delimiter. Variables will be resolved without
7007 escaping anything, therefore you also have to be careful not to chose
7008 delimiters that appear in the replacement text. For example '<' should
7009 be save, while '?' will sooner or later cause conflicts with $url.
7013 The non-standard option letter <literal>T</literal> (trivial) prevents
7014 parsing for backreferences in the substitute. Use it if you want to include
7015 text like '$&' in your substitute without quoting.
7020 <ulink url="https://en.wikipedia.org/wiki/Regular_expressions"><quote>Regular
7021 Expressions</quote></ulink>, you might want to take a look at
7022 the <link linkend="regex">Appendix on regular expressions</link>, and
7023 see the <ulink url="http://perldoc.perl.org/perlre.html">Perl
7025 <ulink url="http://perldoc.perl.org/perlop.html">the
7026 <literal>s///</literal> operator's syntax</ulink> and <ulink
7027 url="http://perldoc.perl.org/perlre.html">Perl-style regular
7028 expressions</ulink> in general.
7029 The below examples might also help to get you started.
7033 <!-- ~~~~~~~~ New section Header ~~~~~~~~~ -->
7035 <sect2 id="filter-file-tut"><title>Filter File Tutorial</title>
7037 Now, let's complete our <quote>foo</quote> content filter. We have already defined
7038 the heading, but the jobs are still missing. Since all it does is to replace
7039 <quote>foo</quote> with <quote>bar</quote>, there is only one (trivial) job
7043 <screen>s/foo/bar/</screen>
7046 But wait! Didn't the comment say that <emphasis>all</emphasis> occurrences
7047 of <quote>foo</quote> should be replaced? Our current job will only take
7048 care of the first <quote>foo</quote> on each page. For global substitution,
7049 we'll need to add the <literal>g</literal> option:
7052 <screen>s/foo/bar/g</screen>
7055 Our complete filter now looks like this:
7058 <screen>FILTER: foo Replace all "foo" with "bar"
7059 s/foo/bar/g</screen>
7062 Let's look at some real filters for more interesting examples. Here you see
7063 a filter that protects against some common annoyances that arise from JavaScript
7064 abuse. Let's look at its jobs one after the other:
7069 FILTER: js-annoyances Get rid of particularly annoying JavaScript abuse
7071 # Get rid of JavaScript referrer tracking. Test page: http://www.randomoddness.com/untitled.htm
7073 s|(<script.*)document\.referrer(.*</script>)|$1"Not Your Business!"$2|Usg</screen>
7076 Following the header line and a comment, you see the job. Note that it uses
7077 <literal>|</literal> as the delimiter instead of <literal>/</literal>, because
7078 the pattern contains a forward slash, which would otherwise have to be escaped
7079 by a backslash (<literal>\</literal>).
7083 Now, let's examine the pattern: it starts with the text <literal><script.*</literal>
7084 enclosed in parentheses. Since the dot matches any character, and <literal>*</literal>
7085 means: <quote>Match an arbitrary number of the element left of myself</quote>, this
7086 matches <quote><script</quote>, followed by <emphasis>any</emphasis> text, i.e.
7087 it matches the whole page, from the start of the first <script> tag.
7091 That's more than we want, but the pattern continues: <literal>document\.referrer</literal>
7092 matches only the exact string <quote>document.referrer</quote>. The dot needed to
7093 be <emphasis>escaped</emphasis>, i.e. preceded by a backslash, to take away its
7094 special meaning as a joker, and make it just a regular dot. So far, the meaning is:
7095 Match from the start of the first <script> tag in a the page, up to, and including,
7096 the text <quote>document.referrer</quote>, if <emphasis>both</emphasis> are present
7097 in the page (and appear in that order).
7101 But there's still more pattern to go. The next element, again enclosed in parentheses,
7102 is <literal>.*</script></literal>. You already know what <literal>.*</literal>
7103 means, so the whole pattern translates to: Match from the start of the first <script>
7104 tag in a page to the end of the last <script> tag, provided that the text
7105 <quote>document.referrer</quote> appears somewhere in between.
7109 This is still not the whole story, since we have ignored the options and the parentheses:
7110 The portions of the page matched by sub-patterns that are enclosed in parentheses, will be
7111 remembered and be available through the variables <literal>$1, $2, ...</literal> in
7112 the substitute. The <literal>U</literal> option switches to ungreedy matching, which means
7113 that the first <literal>.*</literal> in the pattern will only <quote>eat up</quote> all
7114 text in between <quote><script</quote> and the <emphasis>first</emphasis> occurrence
7115 of <quote>document.referrer</quote>, and that the second <literal>.*</literal> will
7116 only span the text up to the <emphasis>first</emphasis> <quote></script></quote>
7117 tag. Furthermore, the <literal>s</literal> option says that the match may span
7118 multiple lines in the page, and the <literal>g</literal> option again means that the
7119 substitution is global.
7123 So, to summarize, the pattern means: Match all scripts that contain the text
7124 <quote>document.referrer</quote>. Remember the parts of the script from
7125 (and including) the start tag up to (and excluding) the string
7126 <quote>document.referrer</quote> as <literal>$1</literal>, and the part following
7127 that string, up to and including the closing tag, as <literal>$2</literal>.
7131 Now the pattern is deciphered, but wasn't this about substituting things? So
7132 lets look at the substitute: <literal>$1"Not Your Business!"$2</literal> is
7133 easy to read: The text remembered as <literal>$1</literal>, followed by
7134 <literal>"Not Your Business!"</literal> (<emphasis>including</emphasis>
7135 the quotation marks!), followed by the text remembered as <literal>$2</literal>.
7136 This produces an exact copy of the original string, with the middle part
7137 (the <quote>document.referrer</quote>) replaced by <literal>"Not Your
7138 Business!"</literal>.
7142 The whole job now reads: Replace <quote>document.referrer</quote> by
7143 <literal>"Not Your Business!"</literal> wherever it appears inside a
7144 <script> tag. Note that this job won't break JavaScript syntax,
7145 since both the original and the replacement are syntactically valid
7146 string objects. The script just won't have access to the referrer
7147 information anymore.
7151 We'll show you two other jobs from the JavaScript taming department, but
7152 this time only point out the constructs of special interest:
7156 # The status bar is for displaying link targets, not pointless blahblah
7158 s/window\.status\s*=\s*(['"]).*?\1/dUmMy=1/ig</screen>
7161 <literal>\s</literal> stands for whitespace characters (space, tab, newline,
7162 carriage return, form feed), so that <literal>\s*</literal> means: <quote>zero
7163 or more whitespace</quote>. The <literal>?</literal> in <literal>.*?</literal>
7164 makes this matching of arbitrary text ungreedy. (Note that the <literal>U</literal>
7165 option is not set). The <literal>['"]</literal> construct means: <quote>a single
7166 <emphasis>or</emphasis> a double quote</quote>. Finally, <literal>\1</literal> is
7167 a back-reference to the first parenthesis just like <literal>$1</literal> above,
7168 with the difference that in the <emphasis>pattern</emphasis>, a backslash indicates
7169 a back-reference, whereas in the <emphasis>substitute</emphasis>, it's the dollar.
7173 So what does this job do? It replaces assignments of single- or double-quoted
7174 strings to the <quote>window.status</quote> object with a dummy assignment
7175 (using a variable name that is hopefully odd enough not to conflict with
7176 real variables in scripts). Thus, it catches many cases where e.g. pointless
7177 descriptions are displayed in the status bar instead of the link target when
7178 you move your mouse over links.
7182 # Kill OnUnload popups. Yummy. Test: http://www.zdnet.com/zdsubs/yahoo/tree/yfs.html
7184 s/(<body [^>]*)onunload(.*>)/$1never$2/iU</screen>
7188 <ulink url="http://www.w3.org/TR/2000/REC-DOM-Level-2-Events-20001113/events.html#Events-eventgroupings-htmlevents">OnUnload
7189 event binding</ulink> in the HTML DOM was a <emphasis>CRIME</emphasis>.
7190 When I close a browser window, I want it to close and die. Basta.
7191 This job replaces the <quote>onunload</quote> attribute in
7192 <quote><body></quote> tags with the dummy word <literal>never</literal>.
7193 Note that the <literal>i</literal> option makes the pattern matching
7194 case-insensitive. Also note that ungreedy matching alone doesn't always guarantee
7195 a minimal match: In the first parenthesis, we had to use <literal>[^>]*</literal>
7196 instead of <literal>.*</literal> to prevent the match from exceeding the
7197 <body> tag if it doesn't contain <quote>OnUnload</quote>, but the page's
7202 The last example is from the fun department:
7206 FILTER: fun Fun text replacements
7208 # Spice the daily news:
7210 s/microsoft(?!\.com)/MicroSuck/ig</screen>
7213 Note the <literal>(?!\.com)</literal> part (a so-called negative lookahead)
7214 in the job's pattern, which means: Don't match, if the string
7215 <quote>.com</quote> appears directly following <quote>microsoft</quote>
7216 in the page. This prevents links to microsoft.com from being trashed, while
7217 still replacing the word everywhere else.
7221 # Buzzword Bingo (example for extended regex syntax)
7223 s* industry[ -]leading \
7225 | customer[ -]focused \
7226 | market[ -]driven \
7227 | award[ -]winning # Comments are OK, too! \
7228 | high[ -]performance \
7229 | solutions[ -]based \
7233 *<font color="red"><b>BINGO!</b></font> \
7237 The <literal>x</literal> option in this job turns on extended syntax, and allows for
7238 e.g. the liberal use of (non-interpreted!) whitespace for nicer formatting.
7246 <!-- ~~~~~~~~ New section Header ~~~~~~~~~ -->
7248 <sect2 id="predefined-filters"><title>The Pre-defined Filters</title>
7252 Note each filter is also listed in the +filter action section above. Please
7253 keep these listings in sync.
7258 The distribution <filename>default.filter</filename> file contains a selection of
7259 pre-defined filters for your convenience:
7264 <term><emphasis>js-annoyances</emphasis></term>
7267 The purpose of this filter is to get rid of particularly annoying JavaScript abuse.
7273 replaces JavaScript references to the browser's referrer information
7274 with the string "Not Your Business!". This compliments the <literal><link
7275 linkend="hide-referrer">hide-referrer</link></literal> action on the content level.
7280 removes the bindings to the DOM's
7281 <ulink url="http://www.w3.org/TR/2000/REC-DOM-Level-2-Events-20001113/events.html#Events-eventgroupings-htmlevents">unload
7282 event</ulink> which we feel has no right to exist and is responsible for most <quote>exit consoles</quote>, i.e.
7283 nasty windows that pop up when you close another one.
7288 removes code that causes new windows to be opened with undesired properties, such as being
7289 full-screen, non-resizeable, without location, status or menu bar etc.
7294 Use with caution. This is an aggressive filter, and can break sites that
7295 rely heavily on JavaScript.
7301 <term><emphasis>js-events</emphasis></term>
7304 This is a very radical measure. It removes virtually all JavaScript event bindings, which
7305 means that scripts can not react to user actions such as mouse movements or clicks, window
7306 resizing etc, anymore. Use with caution!
7309 We <emphasis>strongly discourage</emphasis> using this filter as a default since it breaks
7310 many legitimate scripts. It is meant for use only on extra-nasty sites (should you really
7317 <term><emphasis>html-annoyances</emphasis></term>
7320 This filter will undo many common instances of HTML based abuse.
7323 The <literal>BLINK</literal> and <literal>MARQUEE</literal> tags
7324 are neutralized (yeah baby!), and browser windows will be created as
7325 resizeable (as of course they should be!), and will have location,
7326 scroll and menu bars -- even if specified otherwise.
7332 <term><emphasis>content-cookies</emphasis></term>
7335 Most cookies are set in the HTTP dialog, where they can be intercepted
7337 <literal><link linkend="crunch-incoming-cookies">crunch-incoming-cookies</link></literal>
7338 and <literal><link linkend="crunch-outgoing-cookies">crunch-outgoing-cookies</link></literal>
7339 actions. But web sites increasingly make use of HTML meta tags and JavaScript
7340 to sneak cookies to the browser on the content level.
7343 This filter disables most HTML and JavaScript code that reads or sets
7344 cookies. It cannot detect all clever uses of these types of code, so it
7345 should not be relied on as an absolute fix. Use it wherever you would also
7346 use the cookie crunch actions.
7352 <term><emphasis>refresh-tags</emphasis></term>
7355 Disable any refresh tags if the interval is greater than nine seconds (so
7356 that redirections done via refresh tags are not destroyed). This is useful
7357 for dial-on-demand setups, or for those who find this HTML feature
7364 <term><emphasis>unsolicited-popups</emphasis></term>
7367 This filter attempts to prevent only <quote>unsolicited</quote> pop-up
7368 windows from opening, yet still allow pop-up windows that the user
7369 has explicitly chosen to open. It was added in version 3.0.1,
7370 as an improvement over earlier such filters.
7373 Technical note: The filter works by redefining the window.open JavaScript
7374 function to a dummy function, <literal>PrivoxyWindowOpen()</literal>,
7375 during the loading and rendering phase of each HTML page access, and
7376 restoring the function afterward.
7379 This is recommended only for browsers that cannot perform this function
7380 reliably themselves. And be aware that some sites require such windows
7381 in order to function normally. Use with caution.
7387 <term><emphasis>all-popups</emphasis></term>
7390 Attempt to prevent <emphasis>all</emphasis> pop-up windows from opening.
7391 Note this should be used with even more discretion than the above, since
7392 it is more likely to break some sites that require pop-ups for normal
7393 usage. Use with caution.
7399 <term><emphasis>img-reorder</emphasis></term>
7402 This is a helper filter that has no value if used alone. It makes the
7403 <literal>banners-by-size</literal> and <literal>banners-by-link</literal>
7404 (see below) filters more effective and should be enabled together with them.
7410 <term><emphasis>banners-by-size</emphasis></term>
7413 This filter removes image tags purely based on what size they are. Fortunately
7414 for us, many ads and banner images tend to conform to certain standardized
7415 sizes, which makes this filter quite effective for ad stripping purposes.
7418 Occasionally this filter will cause false positives on images that are not ads,
7419 but just happen to be of one of the standard banner sizes.
7422 Recommended only for those who require extreme ad blocking. The default
7423 block rules should catch 95+% of all ads <emphasis>without</emphasis> this filter enabled.
7429 <term><emphasis>banners-by-link</emphasis></term>
7432 This is an experimental filter that attempts to kill any banners if
7433 their URLs seem to point to known or suspected click trackers. It is currently
7434 not of much value and is not recommended for use by default.
7440 <term><emphasis>webbugs</emphasis></term>
7443 Webbugs are small, invisible images (technically 1X1 GIF images), that
7444 are used to track users across websites, and collect information on them.
7445 As an HTML page is loaded by the browser, an embedded image tag causes the
7446 browser to contact a third-party site, disclosing the tracking information
7447 through the requested URL and/or cookies for that third-party domain, without
7448 the user ever becoming aware of the interaction with the third-party site.
7449 HTML-ized spam also uses a similar technique to verify email addresses.
7452 This filter removes the HTML code that loads such <quote>webbugs</quote>.
7458 <term><emphasis>tiny-textforms</emphasis></term>
7461 A rather special-purpose filter that can be used to enlarge textareas (those
7462 multi-line text boxes in web forms) and turn off hard word wrap in them.
7463 It was written for the sourceforge.net tracker system where such boxes are
7464 a nuisance, but it can be handy on other sites, too.
7467 It is not recommended to use this filter as a default.
7473 <term><emphasis>jumping-windows</emphasis></term>
7476 Many consider windows that move, or resize themselves to be abusive. This filter
7477 neutralizes the related JavaScript code. Note that some sites might not display
7478 or behave as intended when using this filter. Use with caution.
7484 <term><emphasis>frameset-borders</emphasis></term>
7487 Some web designers seem to assume that everyone in the world will view their
7488 web sites using the same browser brand and version, screen resolution etc,
7489 because only that assumption could explain why they'd use static frame sizes,
7490 yet prevent their frames from being resized by the user, should they be too
7491 small to show their whole content.
7494 This filter removes the related HTML code. It should only be applied to sites
7501 <term><emphasis>demoronizer</emphasis></term>
7504 Many Microsoft products that generate HTML use non-standard extensions (read:
7505 violations) of the ISO 8859-1 aka Latin-1 character set. This can cause those
7506 HTML documents to display with errors on standard-compliant platforms.
7509 This filter translates the MS-only characters into Latin-1 equivalents.
7510 It is not necessary when using MS products, and will cause corruption of
7511 all documents that use 8-bit character sets other than Latin-1. It's mostly
7512 worthwhile for Europeans on non-MS platforms, if weird garbage characters
7513 sometimes appear on some pages, or user agents that don't correct for this on
7516 My version of Mozilla (ancient) shows little square boxes for quote
7517 characters, and apostrophes on moronized pages. So many pages have this, I
7518 can read them fine now. HB 08/27/06
7525 <term><emphasis>shockwave-flash</emphasis></term>
7528 A filter for shockwave haters. As the name suggests, this filter strips code
7529 out of web pages that is used to embed shockwave flash objects.
7537 <term><emphasis>quicktime-kioskmode</emphasis></term>
7540 Change HTML code that embeds Quicktime objects so that kioskmode, which
7541 prevents saving, is disabled.
7547 <term><emphasis>fun</emphasis></term>
7550 Text replacements for subversive browsing fun. Make fun of your favorite
7551 Monopolist or play buzzword bingo.
7557 <term><emphasis>crude-parental</emphasis></term>
7560 A demonstration-only filter that shows how <application>Privoxy</application>
7561 can be used to delete web content on a keyword basis.
7567 <term><emphasis>ie-exploits</emphasis></term>
7570 An experimental collection of text replacements to disable malicious HTML and JavaScript
7571 code that exploits known security holes in Internet Explorer.
7574 Presently, it only protects against Nimda and a cross-site scripting bug, and
7575 would need active maintenance to provide more substantial protection.
7581 <term><emphasis>site-specifics</emphasis></term>
7584 Some web sites have very specific problems, the cure for which doesn't apply
7585 anywhere else, or could even cause damage on other sites.
7588 This is a collection of such site-specific cures which should only be applied
7589 to the sites they were intended for, which is what the supplied
7590 <filename>default.action</filename> file does. Users shouldn't need to change
7591 anything regarding this filter.
7597 <term><emphasis>google</emphasis></term>
7600 A CSS based block for Google text ads. Also removes a width limitation
7601 and the toolbar advertisement.
7607 <term><emphasis>yahoo</emphasis></term>
7610 Another CSS based block, this time for Yahoo text ads. And removes
7611 a width limitation as well.
7617 <term><emphasis>msn</emphasis></term>
7620 Another CSS based block, this time for MSN text ads. And removes
7621 tracking URLs, as well as a width limitation.
7627 <term><emphasis>blogspot</emphasis></term>
7630 Cleans up some Blogspot blogs. Read the fine print before using this one!
7633 This filter also intentionally removes some navigation stuff and sets the
7634 page width to 100%. As a result, some rounded <quote>corners</quote> would
7635 appear to early or not at all and as fixing this would require a browser
7636 that understands background-size (CSS3), they are removed instead.
7642 <term><emphasis>xml-to-html</emphasis></term>
7645 Server-header filter to change the Content-Type from xml to html.
7651 <term><emphasis>html-to-xml</emphasis></term>
7654 Server-header filter to change the Content-Type from html to xml.
7660 <term><emphasis>no-ping</emphasis></term>
7663 Removes the non-standard <literal>ping</literal> attribute from
7664 anchor and area HTML tags.
7670 <term><emphasis>hide-tor-exit-notation</emphasis></term>
7673 Client-header filter to remove the <command>Tor</command> exit node notation
7674 found in Host and Referer headers.
7677 If &my-app; and <command>Tor</command> are chained and &my-app;
7678 is configured to use socks4a, one can use <quote>http://www.example.org.foobar.exit/</quote>
7679 to access the host <quote>www.example.org</quote> through the
7680 <command>Tor</command> exit node <quote>foobar</quote>.
7683 As the HTTP client isn't aware of this notation, it treats the
7684 whole string <quote>www.example.org.foobar.exit</quote> as host and uses it
7685 for the <quote>Host</quote> and <quote>Referer</quote> headers. From the
7686 server's point of view the resulting headers are invalid and can cause problems.
7689 An invalid <quote>Referer</quote> header can trigger <quote>hot-linking</quote>
7690 protections, an invalid <quote>Host</quote> header will make it impossible for
7691 the server to find the right vhost (several domains hosted on the same IP address).
7694 This client-header filter removes the <quote>foo.exit</quote> part in those headers
7695 to prevent the mentioned problems. Note that it only modifies
7696 the HTTP headers, it doesn't make it impossible for the server
7697 to detect your <command>Tor</command> exit node based on the IP address
7698 the request is coming from.
7705 <term><emphasis> </emphasis></term>
7718 <!-- ~~~~~~~~ New section Header ~~~~~~~~~ -->
7719 <sect2 id="external-filter-syntax"><title>External filter syntax</title>
7721 External filters are scripts or programs that can modify the content in
7722 case common <literal><link linkend="filter">filters</link></literal>
7723 aren't powerful enough.
7726 External filters can be written in any language the platform &my-app; runs
7730 They are controlled with the
7731 <literal><link linkend="external-filter">external-filter</link></literal> action
7732 and have to be defined in the <literal><link linkend="filterfile">filterfile</link></literal>
7736 The header looks like any other filter, but instead of pcrs jobs, external
7737 filters contain a single job which can be a program or a shell script (which
7738 may call other scripts or programs).
7741 External filters read the content from STDIN and write the rewritten
7743 The environment variables PRIVOXY_URL, PRIVOXY_PATH, PRIVOXY_HOST,
7744 PRIVOXY_ORIGIN, PRIVOXY_LISTEN_ADDRESS can be used to get some details
7745 about the client request.
7748 &my-app; will temporary store the content to filter in the
7749 <literal><link linkend="temporary-directory">temporary-directory</link></literal>.
7753 EXTERNAL-FILTER: cat Pointless example filter that doesn't actually modify the content
7756 # Incorrect reimplementation of the filter above in POSIX shell.
7758 # Note that it's a single job that spans multiple lines, the line
7759 # breaks are not passed to the shell, thus the semicolons are required.
7761 # If the script isn't trivial, it is recommended to put it into an external file.
7763 # In general, writing external filters entirely in POSIX shell is not
7764 # considered a good idea.
7765 EXTERNAL-FILTER: cat2 Pointless example filter that despite its name may actually modify the content
7771 EXTERNAL-FILTER: rotate-image Rotate an image by 180 degree. Test filter with limited value.
7772 /usr/local/bin/convert - -rotate 180 -
7774 EXTERNAL-FILTER: citation-needed Adds a "[citation needed]" tag to an image. The coordinates may need adjustment.
7775 /usr/local/bin/convert - -pointsize 16 -fill white -annotate +17+418 "[citation needed]" -
7780 Currently external filters are executed with &my-app;'s privileges!
7781 Only use external filters you understand and trust.
7785 External filters are experimental and the syntax may change in the future.
7791 <!-- ~ End section ~ -->
7795 <!-- ~~~~~ New section ~~~~~ -->
7797 <sect1 id="templates">
7798 <title>Privoxy's Template Files</title>
7800 All <application>Privoxy</application> built-in pages, i.e. error pages such as the
7801 <ulink url="http://show-the-404-error.page"><quote>404 - No Such Domain</quote>
7802 error page</ulink>, the <ulink
7803 url="http://ads.bannerserver.example.com/nasty-ads/sponsor.html"><quote>BLOCKED</quote>
7805 and all pages of its <ulink url="http://config.privoxy.org/">web-based
7806 user interface</ulink>, are generated from <emphasis>templates</emphasis>.
7807 (<application>Privoxy</application> must be running for the above links to work as
7812 These templates are stored in a subdirectory of the <link linkend="confdir">configuration
7813 directory</link> called <filename>templates</filename>. On Unixish platforms,
7815 <ulink url="file:///etc/privoxy/templates/"><filename>/etc/privoxy/templates/</filename></ulink>.
7819 The templates are basically normal HTML files, but with place-holders (called symbols
7820 or exports), which <application>Privoxy</application> fills at run time. It
7821 is possible to edit the templates with a normal text editor, should you want
7822 to customize them. (<emphasis>Not recommended for the casual
7823 user</emphasis>). Should you create your own custom templates, you should use
7824 the <filename>config</filename> setting <link linkend="templdir">templdir</link>
7825 to specify an alternate location, so your templates do not get overwritten
7829 Note that just like in configuration files, lines starting
7830 with <literal>#</literal> are ignored when the templates are filled in.
7834 The place-holders are of the form <literal>@name@</literal>, and you will
7835 find a list of available symbols, which vary from template to template,
7836 in the comments at the start of each file. Note that these comments are not
7837 always accurate, and that it's probably best to look at the existing HTML
7838 code to find out which symbols are supported and what they are filled in with.
7842 A special application of this substitution mechanism is to make whole
7843 blocks of HTML code disappear when a specific symbol is set. We use this
7844 for many purposes, one of them being to include the beta warning in all
7845 our user interface (CGI) pages when <application>Privoxy</application>
7846 is in an alpha or beta development stage:
7850 <!-- @if-unstable-start -->
7852 ... beta warning HTML code goes here ...
7854 <!-- if-unstable-end@ --></screen>
7857 If the "unstable" symbol is set, everything in between and including
7858 <literal>@if-unstable-start</literal> and <literal>if-unstable-end@</literal>
7859 will disappear, leaving nothing but an empty comment:
7862 <screen><!-- --></screen>
7865 There's also an if-then-else construct and an <literal>#include</literal>
7866 mechanism, but you'll sure find out if you are inclined to edit the
7871 All templates refer to a style located at
7872 <ulink url="http://config.privoxy.org/send-stylesheet"><literal>http://config.privoxy.org/send-stylesheet</literal></ulink>.
7873 This is, of course, locally served by <application>Privoxy</application>
7874 and the source for it can be found and edited in the
7875 <filename>cgi-style.css</filename> template.
7880 <!-- ~ End section ~ -->
7884 <!-- ~~~~~ New section ~~~~~ -->
7886 <sect1 id="contact"><title>Contacting the Developers, Bug Reporting and Feature
7889 <!-- Include contacting.sgml boilerplate: -->
7891 <!-- end boilerplate -->
7895 <!-- ~ End section ~ -->
7898 <!-- ~~~~~ New section ~~~~~ -->
7899 <sect1 id="copyright"><title>Privoxy Copyright, License and History</title>
7901 <!-- Include copyright.sgml: -->
7903 <!-- end copyright -->
7906 <application>Privoxy</application> is free software; you can
7907 redistribute and/or modify its source code under the terms
7908 of the <citetitle>GNU General Public License</citetitle>
7909 as published by the Free Software Foundation, either version 2
7910 of the license, or (at your option) any later version.
7914 The same is true for <application>Privoxy</application> binaries
7915 unless they are linked with a
7916 <ulink url="https://tls.mbed.org/">mbed TLS</ulink> version
7917 that is licensed under the Apache 2.0 license in which
7918 case you can redistribute and/or modify the <application>Privoxy</application>
7919 binaries under the terms of the <citetitle>GNU General Public License</citetitle>
7920 as published by the Free Software Foundation, either version 3
7921 of the license, or (at your option) any later version.
7925 Both licenses are included in the next section.
7928 <!-- ~~~~~ New section ~~~~~ -->
7929 <sect2 id="license"><title>License</title>
7931 <sect3 id="gplv2"><title>GNU General Public License version 2</title>
7932 <screen><![ RCDATA [ &GPLv2; ]]></screen>
7935 <sect3 id="gplv3"><title>GNU General Public License version 3</title>
7936 <screen><![ RCDATA [ &GPLv3; ]]></screen>
7940 <!-- ~ End section ~ -->
7943 <!-- ~~~~~ New section ~~~~~ -->
7945 <sect2 id="history"><title>History</title>
7946 <!-- Include history.sgml: -->
7948 <!-- end history -->
7951 <sect2 id="authors"><title>Authors</title>
7952 <!-- Include p-authors.sgml: -->
7954 <!-- end authors -->
7959 <!-- ~ End section ~ -->
7962 <!-- ~~~~~ New section ~~~~~ -->
7963 <sect1 id="seealso"><title>See Also</title>
7964 <!-- Include seealso.sgml: -->
7966 <!-- end seealso -->
7971 <!-- ~~~~~ New section ~~~~~ -->
7972 <sect1 id="appendix"><title>Appendix</title>
7975 <!-- ~~~~~ New section ~~~~~ -->
7977 <title>Regular Expressions</title>
7979 <application>Privoxy</application> uses Perl-style <quote>regular
7980 expressions</quote> in its <link linkend="actions-file">actions
7981 files</link> and <link linkend="filter-file">filter file</link>,
7982 through the <ulink url="http://www.pcre.org/">PCRE</ulink> and
7985 <ulink url="http://www.oesterhelt.org/pcrs/">PCRS</ulink> libraries.
7987 <application>PCRS</application> libraries.
7991 If you are reading this, you probably don't understand what <quote>regular
7992 expressions</quote> are, or what they can do. So this will be a very brief
7993 introduction only. A full explanation would require a <ulink
7994 url="http://www.oreilly.com/catalog/regex/">book</ulink> ;-)
7998 Regular expressions provide a language to describe patterns that can be
7999 run against strings of characters (letter, numbers, etc), to see if they
8000 match the string or not. The patterns are themselves (sometimes complex)
8001 strings of literal characters, combined with wild-cards, and other special
8002 characters, called meta-characters. The <quote>meta-characters</quote> have
8003 special meanings and are used to build complex patterns to be matched against.
8004 Perl Compatible Regular Expressions are an especially convenient
8005 <quote>dialect</quote> of the regular expression language.
8009 To make a simple analogy, we do something similar when we use wild-card
8010 characters when listing files with the <command>dir</command> command in DOS.
8011 <literal>*.*</literal> matches all filenames. The <quote>special</quote>
8012 character here is the asterisk which matches any and all characters. We can be
8013 more specific and use <literal>?</literal> to match just individual
8014 characters. So <quote>dir file?.text</quote> would match
8015 <quote>file1.txt</quote>, <quote>file2.txt</quote>, etc. We are pattern
8016 matching, using a similar technique to <quote>regular expressions</quote>!
8020 Regular expressions do essentially the same thing, but are much, much more
8021 powerful. There are many more <quote>special characters</quote> and ways of
8022 building complex patterns however. Let's look at a few of the common ones,
8023 and then some examples:
8028 <emphasis>.</emphasis> - Matches any single character, e.g. <quote>a</quote>,
8029 <quote>A</quote>, <quote>4</quote>, <quote>:</quote>, or <quote>@</quote>.
8035 <emphasis>?</emphasis> - The preceding character or expression is matched ZERO or ONE
8042 <emphasis>+</emphasis> - The preceding character or expression is matched ONE or MORE
8049 <emphasis>*</emphasis> - The preceding character or expression is matched ZERO or MORE
8056 <emphasis>\</emphasis> - The <quote>escape</quote> character denotes that
8057 the following character should be taken literally. This is used where one of the
8058 special characters (e.g. <quote>.</quote>) needs to be taken literally and
8059 not as a special meta-character. Example: <quote>example\.com</quote>, makes
8060 sure the period is recognized only as a period (and not expanded to its
8061 meta-character meaning of any single character).
8067 <emphasis>[ ]</emphasis> - Characters enclosed in brackets will be matched if
8068 any of the enclosed characters are encountered. For instance, <quote>[0-9]</quote>
8069 matches any numeric digit (zero through nine). As an example, we can combine
8070 this with <quote>+</quote> to match any digit one of more times: <quote>[0-9]+</quote>.
8076 <emphasis>( )</emphasis> - parentheses are used to group a sub-expression,
8077 or multiple sub-expressions.
8083 <emphasis>|</emphasis> - The <quote>bar</quote> character works like an
8084 <quote>or</quote> conditional statement. A match is successful if the
8085 sub-expression on either side of <quote>|</quote> matches. As an example:
8086 <quote>/(this|that) example/</quote> uses grouping and the bar character
8087 and would match either <quote>this example</quote> or <quote>that
8088 example</quote>, and nothing else.
8093 These are just some of the ones you are likely to use when matching URLs with
8094 <application>Privoxy</application>, and is a long way from a definitive
8095 list. This is enough to get us started with a few simple examples which may
8096 be more illuminating:
8100 <emphasis><literal>/.*/banners/.*</literal></emphasis> - A simple example
8101 that uses the common combination of <quote>.</quote> and <quote>*</quote> to
8102 denote any character, zero or more times. In other words, any string at all.
8103 So we start with a literal forward slash, then our regular expression pattern
8104 (<quote>.*</quote>) another literal forward slash, the string
8105 <quote>banners</quote>, another forward slash, and lastly another
8106 <quote>.*</quote>. We are building
8107 a directory path here. This will match any file with the path that has a
8108 directory named <quote>banners</quote> in it. The <quote>.*</quote> matches
8109 any characters, and this could conceivably be more forward slashes, so it
8110 might expand into a much longer looking path. For example, this could match:
8111 <quote>/eye/hate/spammers/banners/annoy_me_please.gif</quote>, or just
8112 <quote>/banners/annoying.html</quote>, or almost an infinite number of other
8113 possible combinations, just so it has <quote>banners</quote> in the path
8118 And now something a little more complex:
8122 <emphasis><literal>/.*/adv((er)?ts?|ertis(ing|ements?))?/</literal></emphasis> -
8123 We have several literal forward slashes again (<quote>/</quote>), so we are
8124 building another expression that is a file path statement. We have another
8125 <quote>.*</quote>, so we are matching against any conceivable sub-path, just so
8126 it matches our expression. The only true literal that <emphasis>must
8127 match</emphasis> our pattern is <application>adv</application>, together with
8128 the forward slashes. What comes after the <quote>adv</quote> string is the
8133 Remember the <quote>?</quote> means the preceding expression (either a
8134 literal character or anything grouped with <quote>(...)</quote> in this case)
8135 can exist or not, since this means either zero or one match. So
8136 <quote>((er)?ts?|ertis(ing|ements?))</quote> is optional, as are the
8137 individual sub-expressions: <quote>(er)</quote>,
8138 <quote>(ing|ements?)</quote>, and the <quote>s</quote>. The <quote>|</quote>
8139 means <quote>or</quote>. We have two of those. For instance,
8140 <quote>(ing|ements?)</quote>, can expand to match either <quote>ing</quote>
8141 <emphasis>OR</emphasis> <quote>ements?</quote>. What is being done here, is an
8142 attempt at matching as many variations of <quote>advertisement</quote>, and
8143 similar, as possible. So this would expand to match just <quote>adv</quote>,
8144 or <quote>advert</quote>, or <quote>adverts</quote>, or
8145 <quote>advertising</quote>, or <quote>advertisement</quote>, or
8146 <quote>advertisements</quote>. You get the idea. But it would not match
8147 <quote>advertizements</quote> (with a <quote>z</quote>). We could fix that by
8148 changing our regular expression to:
8149 <quote>/.*/adv((er)?ts?|erti(s|z)(ing|ements?))?/</quote>, which would then match
8154 <emphasis><literal>/.*/advert[0-9]+\.(gif|jpe?g)</literal></emphasis> - Again
8155 another path statement with forward slashes. Anything in the square brackets
8156 <quote>[ ]</quote> can be matched. This is using <quote>0-9</quote> as a
8157 shorthand expression to mean any digit one through nine. It is the same as
8158 saying <quote>0123456789</quote>. So any digit matches. The <quote>+</quote>
8159 means one or more of the preceding expression must be included. The preceding
8160 expression here is what is in the square brackets -- in this case, any digit
8161 one through nine. Then, at the end, we have a grouping: <quote>(gif|jpe?g)</quote>.
8162 This includes a <quote>|</quote>, so this needs to match the expression on
8163 either side of that bar character also. A simple <quote>gif</quote> on one side, and the other
8164 side will in turn match either <quote>jpeg</quote> or <quote>jpg</quote>,
8165 since the <quote>?</quote> means the letter <quote>e</quote> is optional and
8166 can be matched once or not at all. So we are building an expression here to
8167 match image GIF or JPEG type image file. It must include the literal
8168 string <quote>advert</quote>, then one or more digits, and a <quote>.</quote>
8169 (which is now a literal, and not a special character, since it is escaped
8170 with <quote>\</quote>), and lastly either <quote>gif</quote>, or
8171 <quote>jpeg</quote>, or <quote>jpg</quote>. Some possible matches would
8172 include: <quote>//advert1.jpg</quote>,
8173 <quote>/nasty/ads/advert1234.gif</quote>,
8174 <quote>/banners/from/hell/advert99.jpg</quote>. It would not match
8175 <quote>advert1.gif</quote> (no leading slash), or
8176 <quote>/adverts232.jpg</quote> (the expression does not include an
8177 <quote>s</quote>), or <quote>/advert1.jsp</quote> (<quote>jsp</quote> is not
8178 in the expression anywhere).
8182 We are barely scratching the surface of regular expressions here so that you
8183 can understand the default <application>Privoxy</application>
8184 configuration files, and maybe use this knowledge to customize your own
8185 installation. There is much, much more that can be done with regular
8186 expressions. Now that you know enough to get started, you can learn more on
8191 More reading on Perl Compatible Regular expressions:
8192 <ulink url="http://perldoc.perl.org/perlre.html">http://perldoc.perl.org/perlre.html</ulink>
8196 For information on regular expression based substitutions and their applications
8197 in filters, please see the <link linkend="filter-file">filter file tutorial</link>
8202 <!-- ~ End section ~ -->
8205 <!-- ~~~~~ New section ~~~~~ -->
8206 <sect2 id="internal-pages">
8207 <title>Privoxy's Internal Pages</title>
8210 Since <application>Privoxy</application> proxies each requested
8211 web page, it is easy for <application>Privoxy</application> to
8212 trap certain special URLs. In this way, we can talk directly to
8213 <application>Privoxy</application>, and see how it is
8214 configured, see how our rules are being applied, change these
8215 rules and other configuration options, and even turn
8216 <application>Privoxy's</application> filtering off, all with
8221 The URLs listed below are the special ones that allow direct access
8222 to <application>Privoxy</application>. Of course,
8223 <application>Privoxy</application> must be running to access these. If
8224 not, you will get a friendly error message. Internet access is not
8236 <ulink url="http://config.privoxy.org/">http://config.privoxy.org/</ulink>
8240 There is a shortcut: <ulink url="http://p.p/">http://p.p/</ulink> (But it
8241 doesn't provide a fall-back to a real page, in case the request is not
8242 sent through <application>Privoxy</application>)
8248 View and toggle client tags:
8252 <ulink url="http://config.privoxy.org/client-tags">http://config.privoxy.org/client-tags</ulink>
8259 Show information about the current configuration, including viewing and
8260 editing of actions files:
8264 <ulink url="http://config.privoxy.org/show-status">http://config.privoxy.org/show-status</ulink>
8271 Show the browser's request headers:
8275 <ulink url="http://config.privoxy.org/show-request">http://config.privoxy.org/show-request</ulink>
8282 Show which actions apply to a URL and why:
8286 <ulink url="http://config.privoxy.org/show-url-info">http://config.privoxy.org/show-url-info</ulink>
8293 Toggle Privoxy on or off. This feature can be turned off/on in the main
8294 <filename>config</filename> file. When toggled <quote>off</quote>, <quote>Privoxy</quote>
8295 continues to run, but only as a pass-through proxy, with no actions taking
8300 <ulink url="http://config.privoxy.org/toggle">http://config.privoxy.org/toggle</ulink>
8304 Short cuts. Turn off, then on:
8308 <ulink url="http://config.privoxy.org/toggle?set=disable">http://config.privoxy.org/toggle?set=disable</ulink>
8313 <ulink url="http://config.privoxy.org/toggle?set=enable">http://config.privoxy.org/toggle?set=enable</ulink>
8323 <!-- ~~~~~ New section ~~~~~ -->
8325 <title>Chain of Events</title>
8327 Let's take a quick look at how some of <application>Privoxy's</application>
8328 core features are triggered, and the ensuing sequence of events when a web
8329 page is requested by your browser:
8335 First, your web browser requests a web page. The browser knows to send
8336 the request to <application>Privoxy</application>, which will in turn,
8337 relay the request to the remote web server after passing the following
8343 <application>Privoxy</application> traps any request for its own internal CGI
8344 pages (e.g <ulink url="http://p.p/">http://p.p/</ulink>) and sends the CGI page back to the browser.
8349 Next, <application>Privoxy</application> checks to see if the URL
8351 linkend="BLOCK"><quote>+block</quote></link> patterns. If
8352 so, the URL is then blocked, and the remote web server will not be contacted.
8353 <link linkend="HANDLE-AS-IMAGE"><quote>+handle-as-image</quote></link>
8355 <link linkend="HANDLE-AS-EMPTY-DOCUMENT"><quote>+handle-as-empty-document</quote></link>
8356 are then checked, and if there is no match, an
8357 HTML <quote>BLOCKED</quote> page is sent back to the browser. Otherwise, if
8358 it does match, an image is returned for the former, and an empty text
8359 document for the latter. The type of image would depend on the setting of
8360 <link linkend="SET-IMAGE-BLOCKER"><quote>+set-image-blocker</quote></link>
8361 (blank, checkerboard pattern, or an HTTP redirect to an image elsewhere).
8366 Untrusted URLs are blocked. If URLs are being added to the
8367 <filename>trust</filename> file, then that is done.
8372 If the URL pattern matches the <link
8373 linkend="FAST-REDIRECTS"><quote>+fast-redirects</quote></link> action,
8374 it is then processed. Unwanted parts of the requested URL are stripped.
8379 Now the rest of the client browser's request headers are processed. If any
8380 of these match any of the relevant actions (e.g. <link
8381 linkend="HIDE-USER-AGENT"><quote>+hide-user-agent</quote></link>,
8382 etc.), headers are suppressed or forged as determined by these actions and
8388 Now the web server starts sending its response back (i.e. typically a web
8394 First, the server headers are read and processed to determine, among other
8395 things, the MIME type (document type) and encoding. The headers are then
8396 filtered as determined by the
8397 <link linkend="CRUNCH-INCOMING-COOKIES"><quote>+crunch-incoming-cookies</quote></link>,
8398 <link linkend="SESSION-COOKIES-ONLY"><quote>+session-cookies-only</quote></link>,
8399 and <link linkend="DOWNGRADE-HTTP-VERSION"><quote>+downgrade-http-version</quote></link>
8405 If any <link linkend="FILTER"><quote>+filter</quote></link> action
8407 linkend="DEANIMATE-GIFS"><quote>+deanimate-gifs</quote></link>
8408 action applies (and the document type fits the action), the rest of the page is
8409 read into memory (up to a configurable limit). Then the filter rules (from
8410 <filename>default.filter</filename> and any other filter files) are
8411 processed against the buffered content. Filters are applied in the order
8412 they are specified in one of the filter files. Animated GIFs, if present,
8413 are reduced to either the first or last frame, depending on the action
8414 setting.The entire page, which is now filtered, is then sent by
8415 <application>Privoxy</application> back to your browser.
8418 If neither a <link linkend="FILTER"><quote>+filter</quote></link> action
8420 linkend="DEANIMATE-GIFS"><quote>+deanimate-gifs</quote></link>
8421 matches, then <application>Privoxy</application> passes the raw data through
8422 to the client browser as it becomes available.
8427 As the browser receives the now (possibly filtered) page content, it
8428 reads and then requests any URLs that may be embedded within the page
8429 source, e.g. ad images, stylesheets, JavaScript, other HTML documents (e.g.
8430 frames), sounds, etc. For each of these objects, the browser issues a
8431 separate request (this is easily viewable in <application>Privoxy's</application>
8432 logs). And each such request is in turn processed just as above. Note that a
8433 complex web page will have many, many such embedded URLs. If these
8434 secondary requests are to a different server, then quite possibly a very
8435 differing set of actions is triggered.
8442 NOTE: This is somewhat of a simplistic overview of what happens with each URL
8443 request. For the sake of brevity and simplicity, we have focused on
8444 <application>Privoxy's</application> core features only.
8450 <!-- ~~~~~ New section ~~~~~ -->
8451 <sect2 id="actionsanat">
8452 <title>Troubleshooting: Anatomy of an Action</title>
8455 The way <application>Privoxy</application> applies
8456 <link linkend="ACTIONS">actions</link> and <link linkend="FILTER">filters</link>
8457 to any given URL can be complex, and not always so
8458 easy to understand what is happening. And sometimes we need to be able to
8459 <emphasis>see</emphasis> just what <application>Privoxy</application> is
8460 doing. Especially, if something <application>Privoxy</application> is doing
8461 is causing us a problem inadvertently. It can be a little daunting to look at
8462 the actions and filters files themselves, since they tend to be filled with
8463 <link linkend="regex">regular expressions</link> whose consequences are not
8468 One quick test to see if <application>Privoxy</application> is causing a problem
8469 or not, is to disable it temporarily. This should be the first troubleshooting
8470 step (be sure to flush caches afterward!). Looking at the
8471 logs is a good idea too. (Note that both the toggle feature and logging are
8472 enabled via <filename>config</filename> file settings, and may need to be
8473 turned <quote>on</quote>.)
8476 Another easy troubleshooting step to try is if you have done any
8477 customization of your installation, revert back to the installed
8478 defaults and see if that helps. There are times the developers get complaints
8479 about one thing or another, and the problem is more related to a customized
8480 configuration issue.
8484 <application>Privoxy</application> also provides the
8485 <ulink url="http://config.privoxy.org/show-url-info">http://config.privoxy.org/show-url-info</ulink>
8486 page that can show us very specifically how <application>actions</application>
8487 are being applied to any given URL. This is a big help for troubleshooting.
8491 First, enter one URL (or partial URL) at the prompt, and then
8492 <application>Privoxy</application> will tell us
8493 how the current configuration will handle it. This will not
8494 help with filtering effects (i.e. the <link
8495 linkend="FILTER"><quote>+filter</quote></link> action) from
8496 one of the filter files since this is handled very
8497 differently and not so easy to trap! It also will not tell you about any other
8498 URLs that may be embedded within the URL you are testing. For instance, images
8499 such as ads are expressed as URLs within the raw page source of HTML pages. So
8500 you will only get info for the actual URL that is pasted into the prompt area
8501 -- not any sub-URLs. If you want to know about embedded URLs like ads, you
8502 will have to dig those out of the HTML source. Use your browser's <quote>View
8503 Page Source</quote> option for this. Or right click on the ad, and grab the
8508 Let's try an example, <ulink url="http://google.com">google.com</ulink>,
8509 and look at it one section at a time in a sample configuration (your real
8510 configuration may vary):
8514 Matches for http://www.google.com:
8516 In file: default.action <guibutton>[ View ]</guibutton> <guibutton>[ Edit ]</guibutton>
8518 {+change-x-forwarded-for{block}
8519 +deanimate-gifs {last}
8520 +fast-redirects {check-decoded-url}
8521 +filter {refresh-tags}
8522 +filter {img-reorder}
8523 +filter {banners-by-size}
8525 +filter {jumping-windows}
8526 +filter {ie-exploits}
8527 +hide-from-header {block}
8528 +hide-referrer {forge}
8529 +session-cookies-only
8530 +set-image-blocker {pattern}
8533 { -session-cookies-only }
8539 In file: user.action <guibutton>[ View ]</guibutton> <guibutton>[ Edit ]</guibutton>
8540 (no matches in this file)
8544 This is telling us how we have defined our
8545 <link linkend="ACTIONS"><quote>actions</quote></link>, and
8546 which ones match for our test case, <quote>google.com</quote>.
8547 Displayed is all the actions that are available to us. Remember,
8548 the <literal>+</literal> sign denotes <quote>on</quote>. <literal>-</literal>
8549 denotes <quote>off</quote>. So some are <quote>on</quote> here, but many
8550 are <quote>off</quote>. Each example we try may provide a slightly different
8551 end result, depending on our configuration directives.
8555 is for our <filename>default.action</filename> file. The large, multi-line
8556 listing, is how the actions are set to match for all URLs, i.e. our default
8557 settings. If you look at your <quote>actions</quote> file, this would be the
8558 section just below the <quote>aliases</quote> section near the top. This
8559 will apply to all URLs as signified by the single forward slash at the end
8560 of the listing -- <quote> / </quote>.
8564 But we have defined additional actions that would be exceptions to these general
8565 rules, and then we list specific URLs (or patterns) that these exceptions
8566 would apply to. Last match wins. Just below this then are two explicit
8567 matches for <quote>.google.com</quote>. The first is negating our previous
8568 cookie setting, which was for <link
8569 linkend="SESSION-COOKIES-ONLY"><quote>+session-cookies-only</quote></link>
8570 (i.e. not persistent). So we will allow persistent cookies for google, at
8571 least that is how it is in this example. The second turns
8572 <emphasis>off</emphasis> any <link
8573 linkend="FAST-REDIRECTS"><quote>+fast-redirects</quote></link>
8574 action, allowing this to take place unmolested. Note that there is a leading
8575 dot here -- <quote>.google.com</quote>. This will match any hosts and
8576 sub-domains, in the google.com domain also, such as
8577 <quote>www.google.com</quote> or <quote>mail.google.com</quote>. But it would not
8578 match <quote>www.google.de</quote>! So, apparently, we have these two actions
8579 defined as exceptions to the general rules at the top somewhere in the lower
8580 part of our <filename>default.action</filename> file, and
8581 <quote>google.com</quote> is referenced somewhere in these latter sections.
8585 Then, for our <filename>user.action</filename> file, we again have no hits.
8586 So there is nothing google-specific that we might have added to our own, local
8587 configuration. If there was, those actions would over-rule any actions from
8588 previously processed files, such as <filename>default.action</filename>.
8589 <filename>user.action</filename> typically has the last word. This is the
8590 best place to put hard and fast exceptions,
8594 And finally we pull it all together in the bottom section and summarize how
8595 <application>Privoxy</application> is applying all its <quote>actions</quote>
8596 to <quote>google.com</quote>:
8604 +change-x-forwarded-for{block}
8605 -client-header-filter{hide-tor-exit-notation}
8606 -content-type-overwrite
8607 -crunch-client-header
8608 -crunch-if-none-match
8609 -crunch-incoming-cookies
8610 -crunch-outgoing-cookies
8611 -crunch-server-header
8612 +deanimate-gifs {last}
8613 -downgrade-http-version
8616 -filter {content-cookies}
8617 -filter {all-popups}
8618 -filter {banners-by-link}
8619 -filter {tiny-textforms}
8620 -filter {frameset-borders}
8621 -filter {demoronizer}
8622 -filter {shockwave-flash}
8623 -filter {quicktime-kioskmode}
8625 -filter {crude-parental}
8626 -filter {site-specifics}
8627 -filter {js-annoyances}
8628 -filter {html-annoyances}
8629 +filter {refresh-tags}
8630 -filter {unsolicited-popups}
8631 +filter {img-reorder}
8632 +filter {banners-by-size}
8634 +filter {jumping-windows}
8635 +filter {ie-exploits}
8642 -handle-as-empty-document
8644 -hide-accept-language
8645 -hide-content-disposition
8646 +hide-from-header {block}
8647 -hide-if-modified-since
8648 +hide-referrer {forge}
8651 -overwrite-last-modified
8652 -prevent-compression
8654 -server-header-filter{xml-to-html}
8655 -server-header-filter{html-to-xml}
8656 -session-cookies-only
8657 +set-image-blocker {pattern}
8661 Notice the only difference here to the previous listing, is to
8662 <quote>fast-redirects</quote> and <quote>session-cookies-only</quote>,
8663 which are activated specifically for this site in our configuration,
8664 and thus show in the <quote>Final Results</quote>.
8668 Now another example, <quote>ad.doubleclick.net</quote>:
8672 { +block{Domains starts with "ad"} }
8675 { +block{Domain contains "ad"} }
8678 { +block{Doubleclick banner server} +handle-as-image }
8679 .[a-vx-z]*.doubleclick.net
8683 We'll just show the interesting part here - the explicit matches. It is
8684 matched three different times. Two <quote>+block{}</quote> sections,
8685 and a <quote>+block{} +handle-as-image</quote>,
8686 which is the expanded form of one of our aliases that had been defined as:
8687 <quote>+block-as-image</quote>. (<link
8688 linkend="ALIASES"><quote>Aliases</quote></link> are defined in
8689 the first section of the actions file and typically used to combine more
8694 Any one of these would have done the trick and blocked this as an unwanted
8695 image. This is unnecessarily redundant since the last case effectively
8696 would also cover the first. No point in taking chances with these guys
8697 though ;-) Note that if you want an ad or obnoxious
8698 URL to be invisible, it should be defined as <quote>ad.doubleclick.net</quote>
8699 is done here -- as both a <link
8700 linkend="BLOCK"><quote>+block{}</quote></link>
8701 <emphasis>and</emphasis> an
8702 <link linkend="HANDLE-AS-IMAGE"><quote>+handle-as-image</quote></link>.
8703 The custom alias <quote><literal>+block-as-image</literal></quote> just
8704 simplifies the process and make it more readable.
8708 One last example. Let's try <quote>http://www.example.net/adsl/HOWTO/</quote>.
8709 This one is giving us problems. We are getting a blank page. Hmmm ...
8713 Matches for http://www.example.net/adsl/HOWTO/:
8715 In file: default.action <guibutton>[ View ]</guibutton> <guibutton>[ Edit ]</guibutton>
8719 +change-x-forwarded-for{block}
8720 -client-header-filter{hide-tor-exit-notation}
8721 -content-type-overwrite
8722 -crunch-client-header
8723 -crunch-if-none-match
8724 -crunch-incoming-cookies
8725 -crunch-outgoing-cookies
8726 -crunch-server-header
8728 -downgrade-http-version
8729 +fast-redirects {check-decoded-url}
8731 -filter {content-cookies}
8732 -filter {all-popups}
8733 -filter {banners-by-link}
8734 -filter {tiny-textforms}
8735 -filter {frameset-borders}
8736 -filter {demoronizer}
8737 -filter {shockwave-flash}
8738 -filter {quicktime-kioskmode}
8740 -filter {crude-parental}
8741 -filter {site-specifics}
8742 -filter {js-annoyances}
8743 -filter {html-annoyances}
8744 +filter {refresh-tags}
8745 -filter {unsolicited-popups}
8746 +filter {img-reorder}
8747 +filter {banners-by-size}
8749 +filter {jumping-windows}
8750 +filter {ie-exploits}
8757 -handle-as-empty-document
8759 -hide-accept-language
8760 -hide-content-disposition
8761 +hide-from-header{block}
8762 +hide-referer{forge}
8764 -overwrite-last-modified
8765 +prevent-compression
8767 -server-header-filter{xml-to-html}
8768 -server-header-filter{html-to-xml}
8769 +session-cookies-only
8770 +set-image-blocker{blank} }
8773 { +block{Path contains "ads".} +handle-as-image }
8778 Ooops, the <quote>/adsl/</quote> is matching <quote>/ads</quote> in our
8779 configuration! But we did not want this at all! Now we see why we get the
8780 blank page. It is actually triggering two different actions here, and
8781 the effects are aggregated so that the URL is blocked, and &my-app; is told
8782 to treat the block as if it were an image. But this is, of course, all wrong.
8783 We could now add a new action below this (or better in our own
8784 <filename>user.action</filename> file) that explicitly
8785 <emphasis>un</emphasis> blocks (
8786 <link linkend="BLOCK"><quote>{-block}</quote></link>) paths with
8787 <quote>adsl</quote> in them (remember, last match in the configuration
8788 wins). There are various ways to handle such exceptions. Example:
8797 Now the page displays ;-)
8798 Remember to flush your browser's caches when making these kinds of changes to
8799 your configuration to insure that you get a freshly delivered page! Or, try
8800 using <literal>Shift+Reload</literal>.
8804 But now what about a situation where we get no explicit matches like
8809 { +block{Path starts with "ads".} +handle-as-image }
8814 That actually was very helpful and pointed us quickly to where the problem
8815 was. If you don't get this kind of match, then it means one of the default
8816 rules in the first section of <filename>default.action</filename> is causing
8817 the problem. This would require some guesswork, and maybe a little trial and
8818 error to isolate the offending rule. One likely cause would be one of the
8819 <link linkend="FILTER"><quote>+filter</quote></link> actions.
8820 These tend to be harder to troubleshoot.
8821 Try adding the URL for the site to one of aliases that turn off
8822 <link linkend="FILTER"><quote>+filter</quote></link>:
8828 .worldpay.com # for quietpc.com
8835 <quote><literal>{ shop }</literal></quote> is an <quote>alias</quote> that expands to
8836 <quote><literal>{ -filter -session-cookies-only }</literal></quote>.
8837 Or you could do your own exception to negate filtering:
8842 # Disable ALL filter actions for sites in this section
8849 This would turn off all filtering for these sites. This is best
8850 put in <filename>user.action</filename>, for local site
8851 exceptions. Note that when a simple domain pattern is used by itself (without
8852 the subsequent path portion), all sub-pages within that domain are included
8853 automatically in the scope of the action.
8857 Images that are inexplicably being blocked, may well be hitting the
8858 <link linkend="FILTER-BANNERS-BY-SIZE"><quote>+filter{banners-by-size}</quote></link>
8860 that images of certain sizes are ad banners (works well
8861 <emphasis>most of the time</emphasis> since these tend to be standardized).
8865 <quote><literal>{ fragile }</literal></quote> is an alias that disables most
8866 actions that are the most likely to cause trouble. This can be used as a
8867 last resort for problem sites.
8872 # Handle with care: easy to break
8874 mybank.example.com</screen>
8878 <emphasis>Remember to flush caches!</emphasis> Note that the
8879 <literal>mail.google</literal> reference lacks the TLD portion (e.g.
8880 <quote>.com</quote>). This will effectively match any TLD with
8881 <literal>google</literal> in it, such as <literal>mail.google.de.</literal>,
8885 If this still does not work, you will have to go through the remaining
8886 actions one by one to find which one(s) is causing the problem.
8895 This program is free software; you can redistribute it
8896 and/or modify it under the terms of the GNU General
8897 Public License as published by the Free Software
8898 Foundation; either version 2 of the License, or (at
8899 your option) any later version.
8901 This program is distributed in the hope that it will
8902 be useful, but WITHOUT ANY WARRANTY; without even the
8903 implied warranty of MERCHANTABILITY or FITNESS FOR A
8904 PARTICULAR PURPOSE. See the GNU General Public
8905 License for more details.
8907 The GNU General Public License should be included with
8908 this file. If not, you can view it at
8909 http://www.gnu.org/copyleft/gpl.html
8910 or write to the Free Software Foundation, Inc.,
8911 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,