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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 Note that to change the destination host for
2937 <link linkend="HTTPS-INSPECTION">https-inspected</link>
2938 requests a protocol and host has to be added to the URI.
2941 If <link linkend="HTTPS-INSPECTION">https inspection</link>
2942 is enabled, the protocol can be downgraded from https to http
2943 but upgrading a request from http to https is currently not
2947 Please refer to the <link linkend="filter-file">filter file chapter</link>
2948 to learn which client-header filters are available by default, and how to
2956 <term>Example usage (section):</term>
2959 # Hide Tor exit notation in Host and Referer Headers
2960 {+client-header-filter{hide-tor-exit-notation}}
2969 <!-- ~~~~~ New section ~~~~~ -->
2970 <sect3 renderas="sect4" id="client-body-filter">
2971 <title>client-body-filter</title>
2975 <term>Typical use:</term>
2978 Rewrite or remove client request body.
2984 <term>Effect:</term>
2987 All request bodies to which this action applies are filtered on-the-fly through
2988 the specified regular expression based substitutions.
2995 <!-- boolean, parameterized, Multi-value -->
2997 <para>Multi-value.</para>
3002 <term>Parameter:</term>
3005 The name of a client-body filter, as defined in one of the
3006 <link linkend="filter-file">filter files</link>.
3015 Please refer to the <link linkend="filter-file">filter file chapter</link>
3016 to learn how to create your own client-body filters.
3019 The distribution <filename>default.filter</filename> file contains a selection of
3020 client-body filters for example purposes.
3023 The amount of data that can be filtered is limited by the
3024 <literal><link linkend="buffer-limit">buffer-limit</link></literal>
3025 option in the main <link linkend="config">config file</link>. The
3026 default is 4096 KB (4 Megs). Once this limit is exceeded, the whole
3027 request body is passed through unfiltered.
3033 <term>Example usage (section):</term>
3036 # Remove "test" everywhere in the request body
3037 {+client-body-filter{remove-test}}
3047 <!-- ~~~~~ New section ~~~~~ -->
3048 <sect3 renderas="sect4" id="client-header-tagger">
3049 <title>client-header-tagger</title>
3053 <term>Typical use:</term>
3056 Block requests based on their headers.
3062 <term>Effect:</term>
3065 Client headers to which this action applies are filtered on-the-fly through
3066 the specified regular expression based substitutions, the result is used as
3074 <!-- boolean, parameterized, Multi-value -->
3076 <para>Multi-value.</para>
3081 <term>Parameter:</term>
3084 The name of a client-header tagger, as defined in one of the
3085 <link linkend="filter-file">filter files</link>.
3094 Client-header taggers are applied to each header on its own,
3095 and as the header isn't modified, each tagger <quote>sees</quote>
3099 Client-header taggers are the first actions that are executed
3100 and their tags can be used to control every other action.
3106 <term>Example usage (section):</term>
3109 # Tag every request with the User-Agent header
3110 {+client-header-tagger{user-agent}}
3113 # Tagging itself doesn't change the action
3114 # settings, sections with TAG patterns do:
3116 # If it's a download agent, use a different forwarding proxy,
3117 # show the real User-Agent and make sure resume works.
3118 {+forward-override{forward-socks5 10.0.0.2:2222 .} \
3119 -hide-if-modified-since \
3120 -overwrite-last-modified \
3125 TAG:^User-Agent: NetBSD-ftp/
3126 TAG:^User-Agent: Novell ZYPP Installer
3127 TAG:^User-Agent: RPM APT-HTTP/
3128 TAG:^User-Agent: fetch libfetch/
3129 TAG:^User-Agent: Ubuntu APT-HTTP/
3130 TAG:^User-Agent: MPlayer/
3134 # Tag all requests with the Range header set
3135 {+client-header-tagger{range-requests}}
3138 # Disable filtering for the tagged requests.
3140 # With filtering enabled Privoxy would remove the Range headers
3141 # to be able to filter the whole response. The downside is that
3142 # it prevents clients from resuming downloads or skipping over
3143 # parts of multimedia files.
3144 {-filter -deanimate-gifs}
3149 # Tag all requests with the client IP address
3151 # (Technically the client IP address isn't included in the
3152 # client headers but client-header taggers can set it anyway.
3153 # For details see the tagger in default.filter)
3154 {+client-header-tagger{client-ip-address}}
3157 # Change forwarding settings for requests coming from address 10.0.0.1
3158 {+forward-override{forward-socks5 127.0.1.2:2222 .}}
3159 TAG:^IP-ADDRESS: 10\.0\.0\.1$
3168 <!-- ~~~~~ New section ~~~~~ -->
3169 <sect3 renderas="sect4" id="content-type-overwrite">
3170 <title>content-type-overwrite</title>
3174 <term>Typical use:</term>
3176 <para>Stop useless download menus from popping up, or change the browser's rendering mode</para>
3181 <term>Effect:</term>
3184 Replaces the <quote>Content-Type:</quote> HTTP server header.
3191 <!-- Boolean, Parameterized, Multi-value -->
3193 <para>Parameterized.</para>
3198 <term>Parameter:</term>
3210 The <quote>Content-Type:</quote> HTTP server header is used by the
3211 browser to decide what to do with the document. The value of this
3212 header can cause the browser to open a download menu instead of
3213 displaying the document by itself, even if the document's format is
3214 supported by the browser.
3217 The declared content type can also affect which rendering mode
3218 the browser chooses. If XHTML is delivered as <quote>text/html</quote>,
3219 many browsers treat it as yet another broken HTML document.
3220 If it is send as <quote>application/xml</quote>, browsers with
3221 XHTML support will only display it, if the syntax is correct.
3224 If you see a web site that proudly uses XHTML buttons, but sets
3225 <quote>Content-Type: text/html</quote>, you can use &my-app;
3226 to overwrite it with <quote>application/xml</quote> and validate
3227 the web master's claim inside your XHTML-supporting browser.
3228 If the syntax is incorrect, the browser will complain loudly.
3231 You can also go the opposite direction: if your browser prints
3232 error messages instead of rendering a document falsely declared
3233 as XHTML, you can overwrite the content type with
3234 <quote>text/html</quote> and have it rendered as broken HTML document.
3237 By default <literal>content-type-overwrite</literal> only replaces
3238 <quote>Content-Type:</quote> headers that look like some kind of text.
3239 If you want to overwrite it unconditionally, you have to combine it with
3240 <literal><link linkend="force-text-mode">force-text-mode</link></literal>.
3241 This limitation exists for a reason, think twice before circumventing it.
3244 Most of the time it's easier to replace this action with a custom
3245 <literal><link linkend="server-header-filter">server-header filter</link></literal>.
3246 It allows you to activate it for every document of a certain site and it will still
3247 only replace the content types you aimed at.
3250 Of course you can apply <literal>content-type-overwrite</literal>
3251 to a whole site and then make URL based exceptions, but it's a lot
3252 more work to get the same precision.
3258 <term>Example usage (sections):</term>
3260 <screen># Check if www.example.net/ really uses valid XHTML
3261 { +content-type-overwrite{application/xml} }
3264 # but leave the content type unmodified if the URL looks like a style sheet
3265 {-content-type-overwrite}
3266 www.example.net/.*\.css$
3267 www.example.net/.*style
3275 <!-- ~~~~~ New section ~~~~~ -->
3276 <sect3 renderas="sect4" id="crunch-client-header">
3280 <title>crunch-client-header</title>
3284 <term>Typical use:</term>
3286 <para>Remove a client header <application>Privoxy</application> has no dedicated action for.</para>
3291 <term>Effect:</term>
3294 Deletes every header sent by the client that contains the string the user supplied as parameter.
3301 <!-- Boolean, Parameterized, Multi-value -->
3303 <para>Parameterized.</para>
3308 <term>Parameter:</term>
3320 This action allows you to block client headers for which no dedicated
3321 <application>Privoxy</application> action exists.
3322 <application>Privoxy</application> will remove every client header that
3323 contains the string you supplied as parameter.
3326 Regular expressions are <emphasis>not supported</emphasis> and you can't
3327 use this action to block different headers in the same request, unless
3328 they contain the same string.
3331 <literal>crunch-client-header</literal> is only meant for quick tests.
3332 If you have to block several different headers, or only want to modify
3333 parts of them, you should use a
3334 <literal><link linkend="client-header-filter">client-header filter</link></literal>.
3338 Don't block any header without understanding the consequences.
3345 <term>Example usage (section):</term>
3347 <screen># Block the non-existent "Privacy-Violation:" client header
3348 { +crunch-client-header{Privacy-Violation:} }
3357 <!-- ~~~~~ New section ~~~~~ -->
3358 <sect3 renderas="sect4" id="crunch-if-none-match">
3359 <title>crunch-if-none-match</title>
3365 <term>Typical use:</term>
3367 <para>Prevent yet another way to track the user's steps between sessions.</para>
3372 <term>Effect:</term>
3375 Deletes the <quote>If-None-Match:</quote> HTTP client header.
3382 <!-- Boolean, Parameterized, Multi-value -->
3384 <para>Boolean.</para>
3389 <term>Parameter:</term>
3401 Removing the <quote>If-None-Match:</quote> HTTP client header
3402 is useful for filter testing, where you want to force a real
3403 reload instead of getting status code <quote>304</quote> which
3404 would cause the browser to use a cached copy of the page.
3407 It is also useful to make sure the header isn't used as a cookie
3408 replacement (unlikely but possible).
3411 Blocking the <quote>If-None-Match:</quote> header shouldn't cause any
3412 caching problems, as long as the <quote>If-Modified-Since:</quote> header
3413 isn't blocked or missing as well.
3416 It is recommended to use this action together with
3417 <literal><link linkend="hide-if-modified-since">hide-if-modified-since</link></literal>
3419 <literal><link linkend="overwrite-last-modified">overwrite-last-modified</link></literal>.
3425 <term>Example usage (section):</term>
3427 <screen># Let the browser revalidate cached documents but don't
3428 # allow the server to use the revalidation headers for user tracking.
3429 {+hide-if-modified-since{-60} \
3430 +overwrite-last-modified{randomize} \
3431 +crunch-if-none-match}
3440 <!-- ~~~~~ New section ~~~~~ -->
3441 <sect3 renderas="sect4" id="crunch-incoming-cookies">
3442 <title>crunch-incoming-cookies</title>
3446 <term>Typical use:</term>
3449 Prevent the web server from setting HTTP cookies on your system
3455 <term>Effect:</term>
3458 Deletes any <quote>Set-Cookie:</quote> HTTP headers from server replies.
3465 <!-- Boolean, Parameterized, Multi-value -->
3467 <para>Boolean.</para>
3472 <term>Parameter:</term>
3484 This action is only concerned with <emphasis>incoming</emphasis> HTTP cookies. For
3485 <emphasis>outgoing</emphasis> HTTP cookies, use
3486 <literal><link linkend="crunch-outgoing-cookies">crunch-outgoing-cookies</link></literal>.
3487 Use <emphasis>both</emphasis> to disable HTTP cookies completely.
3490 It makes <emphasis>no sense at all</emphasis> to use this action in conjunction
3491 with the <literal><link linkend="session-cookies-only">session-cookies-only</link></literal> action,
3492 since it would prevent the session cookies from being set. See also
3493 <literal><link linkend="filter-content-cookies">filter-content-cookies</link></literal>.
3499 <term>Example usage:</term>
3501 <screen>+crunch-incoming-cookies</screen>
3508 <!-- ~~~~~ New section ~~~~~ -->
3509 <sect3 renderas="sect4" id="crunch-server-header">
3510 <title>crunch-server-header</title>
3516 <term>Typical use:</term>
3518 <para>Remove a server header <application>Privoxy</application> has no dedicated action for.</para>
3523 <term>Effect:</term>
3526 Deletes every header sent by the server that contains the string the user supplied as parameter.
3533 <!-- Boolean, Parameterized, Multi-value -->
3535 <para>Parameterized.</para>
3540 <term>Parameter:</term>
3552 This action allows you to block server headers for which no dedicated
3553 <application>Privoxy</application> action exists. <application>Privoxy</application>
3554 will remove every server header that contains the string you supplied as parameter.
3557 Regular expressions are <emphasis>not supported</emphasis> and you can't
3558 use this action to block different headers in the same request, unless
3559 they contain the same string.
3562 <literal>crunch-server-header</literal> is only meant for quick tests.
3563 If you have to block several different headers, or only want to modify
3564 parts of them, you should use a custom
3565 <literal><link linkend="server-header-filter">server-header filter</link></literal>.
3569 Don't block any header without understanding the consequences.
3576 <term>Example usage (section):</term>
3578 <screen># Crunch server headers that try to prevent caching
3579 { +crunch-server-header{no-cache} }
3588 <!-- ~~~~~ New section ~~~~~ -->
3589 <sect3 renderas="sect4" id="crunch-outgoing-cookies">
3590 <title>crunch-outgoing-cookies</title>
3594 <term>Typical use:</term>
3597 Prevent the web server from reading any HTTP cookies from your system
3603 <term>Effect:</term>
3606 Deletes any <quote>Cookie:</quote> HTTP headers from client requests.
3613 <!-- Boolean, Parameterized, Multi-value -->
3615 <para>Boolean.</para>
3620 <term>Parameter:</term>
3632 This action is only concerned with <emphasis>outgoing</emphasis> HTTP cookies. For
3633 <emphasis>incoming</emphasis> HTTP cookies, use
3634 <literal><link linkend="crunch-incoming-cookies">crunch-incoming-cookies</link></literal>.
3635 Use <emphasis>both</emphasis> to disable HTTP cookies completely.
3638 It makes <emphasis>no sense at all</emphasis> to use this action in conjunction
3639 with the <literal><link linkend="session-cookies-only">session-cookies-only</link></literal> action,
3640 since it would prevent the session cookies from being read.
3646 <term>Example usage:</term>
3648 <screen>+crunch-outgoing-cookies</screen>
3656 <!-- ~~~~~ New section ~~~~~ -->
3657 <sect3 renderas="sect4" id="deanimate-gifs">
3658 <title>deanimate-gifs</title>
3662 <term>Typical use:</term>
3664 <para>Stop those annoying, distracting animated GIF images.</para>
3669 <term>Effect:</term>
3672 De-animate GIF animations, i.e. reduce them to their first or last image.
3679 <!-- boolean, parameterized, Multi-value -->
3681 <para>Parameterized.</para>
3686 <term>Parameter:</term>
3689 <quote>last</quote> or <quote>first</quote>
3698 This will also shrink the images considerably (in bytes, not pixels!). If
3699 the option <quote>first</quote> is given, the first frame of the animation
3700 is used as the replacement. If <quote>last</quote> is given, the last
3701 frame of the animation is used instead, which probably makes more sense for
3702 most banner animations, but also has the risk of not showing the entire
3703 last frame (if it is only a delta to an earlier frame).
3706 You can safely use this action with patterns that will also match non-GIF
3707 objects, because no attempt will be made at anything that doesn't look like
3714 <term>Example usage:</term>
3716 <screen>+deanimate-gifs{last}</screen>
3723 <!-- ~~~~~ New section ~~~~~ -->
3724 <sect3 renderas="sect4" id="delay-response">
3725 <title>delay-response</title>
3729 <term>Typical use:</term>
3731 <para>Delay responses to the client to reduce the load</para>
3736 <term>Effect:</term>
3739 Delays responses to the client by sending the response in ca. 10 byte chunks.
3746 <!-- boolean, parameterized, Multi-value -->
3748 <para>Parameterized.</para>
3753 <term>Parameter:</term>
3756 <quote>Number of milliseconds</quote>
3765 Sometimes when JavaScript code is used to fetch advertisements
3766 it doesn't respect Privoxy's blocks and retries to fetch the
3767 same resource again causing unnecessary load on the client.
3770 This action delays responses to the client and can be combined
3771 with <literal><link linkend="block">blocks</link></literal>
3772 to slow down the JavaScript code, thus reducing
3773 the load on the client.
3776 When used without <literal><link linkend="block">blocks</link></literal>
3777 the action can also be used to simulate a slow internet connection.
3783 <term>Example usage:</term>
3785 <screen>+delay-response{100}</screen>
3792 <!-- ~~~~~ New section ~~~~~ -->
3793 <sect3 renderas="sect4" id="downgrade-http-version">
3794 <title>downgrade-http-version</title>
3798 <term>Typical use:</term>
3800 <para>Work around (very rare) problems with HTTP/1.1</para>
3805 <term>Effect:</term>
3808 Downgrades HTTP/1.1 client requests and server replies to HTTP/1.0.
3815 <!-- boolean, parameterized, Multi-value -->
3817 <para>Boolean.</para>
3822 <term>Parameter:</term>
3834 This is a left-over from the time when <application>Privoxy</application>
3835 didn't support important HTTP/1.1 features well. It is left here for the
3836 unlikely case that you experience HTTP/1.1-related problems with some server
3840 Note that enabling this action is only a workaround. It should not
3841 be enabled for sites that work without it. While it shouldn't break
3842 any pages, it has an (usually negative) performance impact.
3845 If you come across a site where enabling this action helps, please report it,
3846 so the cause of the problem can be analyzed. If the problem turns out to be
3847 caused by a bug in <application>Privoxy</application> it should be
3848 fixed so the following release works without the work around.
3854 <term>Example usage (section):</term>
3856 <screen>{+downgrade-http-version}
3857 problem-host.example.com</screen>
3865 <!-- ~~~~~ New section ~~~~~ -->
3866 <sect3 renderas="sect4" id="external-filter">
3867 <title>external-filter</title>
3871 <term>Typical use:</term>
3873 <para>Modify content using a programming language of your choice.</para>
3878 <term>Effect:</term>
3881 All instances of text-based type, most notably HTML and JavaScript, to which
3882 this action applies, can be filtered on-the-fly through the specified external
3884 By default plain text documents are exempted from filtering, because web
3885 servers often use the <literal>text/plain</literal> MIME type for all files
3886 whose type they don't know.)
3893 <!-- boolean, parameterized, Multi-value -->
3895 <para>Multi-value.</para>
3900 <term>Parameter:</term>
3903 The name of an external content filter, as defined in the
3904 <link linkend="filter-file">filter file</link>.
3905 External filters can be defined in one or more files as defined by the
3906 <literal><link linkend="filterfile">filterfile</link></literal>
3907 option in the <link linkend="config">config file</link>.
3910 When used in its negative form,
3911 and without parameters, <emphasis>all</emphasis> filtering with external
3912 filters is completely disabled.
3921 External filters are scripts or programs that can modify the content in
3922 case common <literal><link linkend="filter">filters</link></literal>
3923 aren't powerful enough. With the exception that this action doesn't
3924 use pcrs-based filters, the notes in the
3925 <literal><link linkend="filter">filter</link></literal> section apply.
3929 Currently external filters are executed with &my-app;'s privileges.
3930 Only use external filters you understand and trust.
3934 This feature is experimental, the <literal><link
3935 linkend="external-filter-syntax">syntax</link></literal>
3936 may change in the future.
3943 <term>Example usage:</term>
3945 <screen>+external-filter{fancy-filter}</screen>
3951 <!-- ~~~~~ New section ~~~~~ -->
3952 <sect3 renderas="sect4" id="fast-redirects">
3953 <title>fast-redirects</title>
3957 <term>Typical use:</term>
3959 <para>Fool some click-tracking scripts and speed up indirect links.</para>
3964 <term>Effect:</term>
3967 Detects redirection URLs and redirects the browser without contacting
3968 the redirection server first.
3975 <!-- boolean, parameterized, Multi-value -->
3977 <para>Parameterized.</para>
3982 <term>Parameter:</term>
3987 <quote>simple-check</quote> to just search for the string <quote>http://</quote>
3988 to detect redirection URLs.
3993 <quote>check-decoded-url</quote> to decode URLs (if necessary) before searching
3994 for redirection URLs.
4005 Many sites, like yahoo.com, don't just link to other sites. Instead, they
4006 will link to some script on their own servers, giving the destination as a
4007 parameter, which will then redirect you to the final target. URLs
4008 resulting from this scheme typically look like:
4009 <quote>http://www.example.org/click-tracker.cgi?target=http%3a//www.example.net/</quote>.
4012 Sometimes, there are even multiple consecutive redirects encoded in the
4013 URL. These redirections via scripts make your web browsing more traceable,
4014 since the server from which you follow such a link can see where you go
4015 to. Apart from that, valuable bandwidth and time is wasted, while your
4016 browser asks the server for one redirect after the other. Plus, it feeds
4020 This feature is currently not very smart and is scheduled for improvement.
4021 If it is enabled by default, you will have to create some exceptions to
4022 this action. It can lead to failures in several ways:
4025 Not every URLs with other URLs as parameters is evil.
4026 Some sites offer a real service that requires this information to work.
4027 For example a validation service needs to know, which document to validate.
4028 <literal>fast-redirects</literal> assumes that every URL parameter that
4029 looks like another URL is a redirection target, and will always redirect to
4030 the last one. Most of the time the assumption is correct, but if it isn't,
4031 the user gets redirected anyway.
4034 Another failure occurs if the URL contains other parameters after the URL parameter.
4036 <quote>http://www.example.org/?redirect=http%3a//www.example.net/&foo=bar</quote>.
4037 contains the redirection URL <quote>http://www.example.net/</quote>,
4038 followed by another parameter. <literal>fast-redirects</literal> doesn't know that
4039 and will cause a redirect to <quote>http://www.example.net/&foo=bar</quote>.
4040 Depending on the target server configuration, the parameter will be silently ignored
4041 or lead to a <quote>page not found</quote> error. You can prevent this problem by
4042 first using the <literal><link linkend="redirect">redirect</link></literal> action
4043 to remove the last part of the URL, but it requires a little effort.
4046 To detect a redirection URL, <literal>fast-redirects</literal> only
4047 looks for the string <quote>http://</quote>, either in plain text
4048 (invalid but often used) or encoded as <quote>http%3a//</quote>.
4049 Some sites use their own URL encoding scheme, encrypt the address
4050 of the target server or replace it with a database id. In these cases
4051 <literal>fast-redirects</literal> is fooled and the request reaches the
4052 redirection server where it probably gets logged.
4058 <term>Example usage:</term>
4061 { +fast-redirects{simple-check} }
4064 { +fast-redirects{check-decoded-url} }
4065 another.example.com/testing</screen>
4073 <!-- ~~~~~ New section ~~~~~ -->
4074 <sect3 renderas="sect4" id="filter">
4075 <title>filter</title>
4079 <term>Typical use:</term>
4081 <para>Get rid of HTML and JavaScript annoyances, banner advertisements (by size),
4082 do fun text replacements, add personalized effects, etc.</para>
4087 <term>Effect:</term>
4090 All instances of text-based type, most notably HTML and JavaScript, to which
4091 this action applies, can be filtered on-the-fly through the specified regular
4092 expression based substitutions. (Note: as of version 3.0.3 plain text documents
4093 are exempted from filtering, because web servers often use the
4094 <literal>text/plain</literal> MIME type for all files whose type they don't know.)
4101 <!-- boolean, parameterized, Multi-value -->
4103 <para>Multi-value.</para>
4108 <term>Parameter:</term>
4111 The name of a content filter, as defined in the <link linkend="filter-file">filter file</link>.
4112 Filters can be defined in one or more files as defined by the
4113 <literal><link linkend="filterfile">filterfile</link></literal>
4114 option in the <link linkend="config">config file</link>.
4115 <filename>default.filter</filename> is the collection of filters
4116 supplied by the developers. Locally defined filters should go
4117 in their own file, such as <filename>user.filter</filename>.
4120 When used in its negative form,
4121 and without parameters, <emphasis>all</emphasis> filtering is completely disabled.
4130 For your convenience, there are a number of pre-defined filters available
4131 in the distribution filter file that you can use. See the examples below for
4135 Filtering requires buffering the page content, which may appear to
4136 slow down page rendering since nothing is displayed until all content has
4137 passed the filters. (The total time until the page is completely rendered
4138 doesn't change much, but it may be perceived as slower since the page is
4139 not incrementally displayed.)
4140 This effect will be more noticeable on slower connections.
4143 <quote>Rolling your own</quote>
4144 filters requires a knowledge of
4145 <ulink url="https://en.wikipedia.org/wiki/Regular_expressions"><quote>Regular
4146 Expressions</quote></ulink> and
4147 <ulink url="https://en.wikipedia.org/wiki/Html"><quote>HTML</quote></ulink>.
4148 This is very powerful feature, and potentially very intrusive.
4149 Filters should be used with caution, and where an equivalent
4150 <quote>action</quote> is not available.
4153 The amount of data that can be filtered is limited by the
4154 <literal><link linkend="buffer-limit">buffer-limit</link></literal>
4155 option in the main <link linkend="config">config file</link>. The
4156 default is 4096 KB (4 Megs). Once this limit is exceeded, the buffered
4157 data, and all pending data, is passed through unfiltered.
4160 Inappropriate MIME types, such as zipped files, are not filtered at all.
4161 (Again, only text-based types except plain text). Encrypted SSL data
4162 (from HTTPS servers) cannot be filtered either, since this would violate
4163 the integrity of the secure transaction. In some situations it might
4164 be necessary to protect certain text, like source code, from filtering
4165 by defining appropriate <literal>-filter</literal> exceptions.
4168 Compressed content can't be filtered either, but if &my-app;
4169 is compiled with zlib support and a supported compression algorithm
4170 is used (gzip or deflate), &my-app; can first decompress the content
4174 If you use a &my-app; version without zlib support, but want filtering to work on
4175 as much documents as possible, even those that would normally be sent compressed,
4176 you must use the <literal><link linkend="prevent-compression">prevent-compression</link></literal>
4177 action in conjunction with <literal>filter</literal>.
4180 Content filtering can achieve some of the same effects as the
4181 <literal><link linkend="block">block</link></literal>
4182 action, i.e. it can be used to block ads and banners. But the mechanism
4183 works quite differently. One effective use, is to block ad banners
4184 based on their size (see below), since many of these seem to be somewhat
4188 <link linkend="contact">Feedback</link> with suggestions for new or
4189 improved filters is particularly welcome!
4192 The below list has only the names and a one-line description of each
4193 predefined filter. There are <link linkend="predefined-filters">more
4194 verbose explanations</link> of what these filters do in the <link
4195 linkend="filter-file">filter file chapter</link>.
4201 <term>Example usage (with filters from the distribution <filename>default.filter</filename> file).
4202 See <link linkend="PREDEFINED-FILTERS">the Predefined Filters section</link> for
4203 more explanation on each:</term>
4206 <anchor id="filter-js-annoyances">
4208 <screen>+filter{js-annoyances} # Get rid of particularly annoying JavaScript abuse.</screen>
4210 <anchor id="filter-js-events">
4212 <screen>+filter{js-events} # Kill JavaScript event bindings and timers (Radically destructive! Only for extra nasty sites).</screen>
4214 <anchor id="filter-html-annoyances">
4216 <screen>+filter{html-annoyances} # Get rid of particularly annoying HTML abuse.</screen>
4218 <anchor id="filter-content-cookies">
4220 <screen>+filter{content-cookies} # Kill cookies that come in the HTML or JS content.</screen>
4222 <anchor id="filter-refresh-tags">
4224 <screen>+filter{refresh-tags} # Kill automatic refresh tags if refresh time is larger than 9 seconds.</screen>
4226 <anchor id="filter-unsolicited-popups">
4228 <screen>+filter{unsolicited-popups} # Disable only unsolicited pop-up windows.</screen>
4230 <anchor id="filter-all-popups">
4232 <screen>+filter{all-popups} # Kill all popups in JavaScript and HTML.</screen>
4234 <anchor id="filter-img-reorder">
4236 <screen>+filter{img-reorder} # Reorder attributes in <img> tags to make the banners-by-* filters more effective.</screen>
4238 <anchor id="filter-banners-by-size">
4240 <screen>+filter{banners-by-size} # Kill banners by size.</screen>
4242 <anchor id="filter-banners-by-link">
4244 <screen>+filter{banners-by-link} # Kill banners by their links to known clicktrackers.</screen>
4246 <anchor id="filter-webbugs">
4248 <screen>+filter{webbugs} # Squish WebBugs (1x1 invisible GIFs used for user tracking).</screen>
4250 <anchor id="filter-tiny-textforms">
4252 <screen>+filter{tiny-textforms} # Extend those tiny textareas up to 40x80 and kill the hard wrap.</screen>
4254 <anchor id="filter-jumping-windows">
4256 <screen>+filter{jumping-windows} # Prevent windows from resizing and moving themselves.</screen>
4258 <anchor id="filter-frameset-borders">
4260 <screen>+filter{frameset-borders} # Give frames a border and make them resizable.</screen>
4262 <anchor id="filter-iframes">
4264 <screen>+filter{iframes} # Removes all detected iframes. Should only be enabled for individual sites.</screen>
4266 <anchor id="filter-demoronizer">
4268 <screen>+filter{demoronizer} # Fix MS's non-standard use of standard charsets.</screen>
4270 <anchor id="filter-shockwave-flash">
4272 <screen>+filter{shockwave-flash} # Kill embedded Shockwave Flash objects.</screen>
4274 <anchor id="filter-quicktime-kioskmode">
4276 <screen>+filter{quicktime-kioskmode} # Make Quicktime movies saveable.</screen>
4278 <anchor id="filter-fun">
4280 <screen>+filter{fun} # Text replacements for subversive browsing fun!</screen>
4282 <anchor id="filter-crude-parental">
4284 <screen>+filter{crude-parental} # Crude parental filtering. Note that this filter doesn't work reliably.</screen>
4286 <anchor id="filter-ie-exploits">
4288 <screen>+filter{ie-exploits} # Disable some known Internet Explorer bug exploits.</screen>
4290 <anchor id="filter-site-specifics">
4292 <screen>+filter{site-specifics} # Cure for site-specific problems. Don't apply generally!</screen>
4294 <anchor id="filter-no-ping">
4296 <screen>+filter{no-ping} # Removes non-standard ping attributes in <a> and <area> tags.</screen>
4298 <anchor id="filter-google">
4300 <screen>+filter{google} # CSS-based block for Google text ads. Also removes a width limitation and the toolbar advertisement.</screen>
4302 <anchor id="filter-yahoo">
4304 <screen>+filter{yahoo} # CSS-based block for Yahoo text ads. Also removes a width limitation.</screen>
4306 <anchor id="filter-msn">
4308 <screen>+filter{msn} # CSS-based block for MSN text ads. Also removes tracking URLs and a width limitation.</screen>
4310 <anchor id="filter-blogspot">
4312 <screen>+filter{blogspot} # Cleans up some Blogspot blogs. Read the fine print before using this.</screen>
4319 <!-- ~~~~~ New section ~~~~~ -->
4320 <sect3 renderas="sect4" id="force-text-mode">
4321 <title>force-text-mode</title>
4327 <term>Typical use:</term>
4329 <para>Force <application>Privoxy</application> to treat a document as if it was in some kind of <emphasis>text</emphasis> format. </para>
4334 <term>Effect:</term>
4337 Declares a document as text, even if the <quote>Content-Type:</quote> isn't detected as such.
4344 <!-- Boolean, Parameterized, Multi-value -->
4346 <para>Boolean.</para>
4351 <term>Parameter:</term>
4363 As explained <literal><link linkend="filter">above</link></literal>,
4364 <application>Privoxy</application> tries to only filter files that are
4365 in some kind of text format. The same restrictions apply to
4366 <literal><link linkend="content-type-overwrite">content-type-overwrite</link></literal>.
4367 <literal>force-text-mode</literal> declares a document as text,
4368 without looking at the <quote>Content-Type:</quote> first.
4372 Think twice before activating this action. Filtering binary data
4373 with regular expressions can cause file damage.
4380 <term>Example usage:</term>
4391 <!-- ~~~~~ New section ~~~~~ -->
4392 <sect3 renderas="sect4" id="forward-override">
4393 <title>forward-override</title>
4399 <term>Typical use:</term>
4401 <para>Change the forwarding settings based on User-Agent or request origin</para>
4406 <term>Effect:</term>
4409 Overrules the forward directives in the configuration file.
4416 <!-- Boolean, Parameterized, Multi-value -->
4418 <para>Parameterized.</para>
4423 <term>Parameter:</term>
4427 <para><quote>forward .</quote> to use a direct connection without any additional proxies.</para>
4431 <quote>forward 127.0.0.1:8123</quote> to use the HTTP proxy listening at 127.0.0.1 port 8123.
4436 <quote>forward-socks4a 127.0.0.1:9050 .</quote> to use the socks4a proxy listening at
4437 127.0.0.1 port 9050. Replace <quote>forward-socks4a</quote> with <quote>forward-socks4</quote>
4438 to use a socks4 connection (with local DNS resolution) instead, use <quote>forward-socks5</quote>
4439 for socks5 connections (with remote DNS resolution).
4444 <quote>forward-socks4a 127.0.0.1:9050 proxy.example.org:8000</quote> to use the socks4a proxy
4445 listening at 127.0.0.1 port 9050 to reach the HTTP proxy listening at proxy.example.org port 8000.
4446 Replace <quote>forward-socks4a</quote> with <quote>forward-socks4</quote> to use a socks4 connection
4447 (with local DNS resolution) instead, use <quote>forward-socks5</quote>
4448 for socks5 connections (with remote DNS resolution).
4453 <quote>forward-webserver 127.0.0.1:80</quote> to use the HTTP
4454 server listening at 127.0.0.1 port 80 without adjusting the
4458 This makes it more convenient to use Privoxy to make
4459 existing websites available as onion services as well.
4462 Many websites serve content with hardcoded URLs and
4463 can't be easily adjusted to change the domain based
4464 on the one used by the client.
4467 Putting Privoxy between Tor and the webserver (or an stunnel
4468 that forwards to the webserver) allows to rewrite headers and
4469 content to make client and server happy at the same time.
4472 Using Privoxy for webservers that are only reachable through
4473 onion addresses and whose location is supposed to be secret
4474 is not recommended and should not be necessary anyway.
4485 This action takes parameters similar to the
4486 <link linkend="forwarding">forward</link> directives in the configuration
4487 file, but without the URL pattern. It can be used as replacement, but normally it's only
4488 used in cases where matching based on the request URL isn't sufficient.
4492 Please read the description for the <link linkend="forwarding">forward</link> directives before
4493 using this action. Forwarding to the wrong people will reduce your privacy and increase the
4494 chances of man-in-the-middle attacks.
4497 If the ports are missing or invalid, default values will be used. This might change
4498 in the future and you shouldn't rely on it. Otherwise incorrect syntax causes Privoxy
4499 to exit. Due to design limitations, invalid parameter syntax isn't detected until the
4500 action is used the first time.
4503 Use the <ulink url="http://config.privoxy.org/show-url-info">show-url-info CGI page</ulink>
4504 to verify that your forward settings do what you thought the do.
4511 <term>Example usage:</term>
4514 # Use an ssh tunnel for requests previously tagged as
4515 # <quote>User-Agent: fetch libfetch/2.0</quote> and make sure
4516 # resuming downloads continues to work.
4518 # This way you can continue to use Tor for your normal browsing,
4519 # without overloading the Tor network with your FreeBSD ports updates
4520 # or downloads of bigger files like ISOs.
4522 # Note that HTTP headers are easy to fake and therefore their
4523 # values are as (un)trustworthy as your clients and users.
4524 {+forward-override{forward-socks5 10.0.0.2:2222 .} \
4525 -hide-if-modified-since \
4526 -overwrite-last-modified \
4528 TAG:^User-Agent: fetch libfetch/2\.0$
4536 <!-- ~~~~~ New section ~~~~~ -->
4537 <sect3 renderas="sect4" id="handle-as-empty-document">
4538 <title>handle-as-empty-document</title>
4544 <term>Typical use:</term>
4546 <para>Mark URLs that should be replaced by empty documents <emphasis>if they get blocked</emphasis></para>
4551 <term>Effect:</term>
4554 This action alone doesn't do anything noticeable. It just marks URLs.
4555 If the <literal><link linkend="block">block</link></literal> action <emphasis>also applies</emphasis>,
4556 the presence or absence of this mark decides whether an HTML <quote>BLOCKED</quote>
4557 page, or an empty document will be sent to the client as a substitute for the blocked content.
4558 The <emphasis>empty</emphasis> document isn't literally empty, but actually contains a single space.
4565 <!-- Boolean, Parameterized, Multi-value -->
4567 <para>Boolean.</para>
4572 <term>Parameter:</term>
4584 Some browsers complain about syntax errors if JavaScript documents
4585 are blocked with <application>Privoxy's</application>
4586 default HTML page; this option can be used to silence them.
4587 And of course this action can also be used to eliminate the &my-app;
4588 BLOCKED message in frames.
4591 The content type for the empty document can be specified with
4592 <literal><link linkend="content-type-overwrite">content-type-overwrite{}</link></literal>,
4593 but usually this isn't necessary.
4599 <term>Example usage:</term>
4601 <screen># Block all documents on example.org that end with ".js",
4602 # but send an empty document instead of the usual HTML message.
4603 {+block{Blocked JavaScript} +handle-as-empty-document}
4612 <!-- ~~~~~ New section ~~~~~ -->
4613 <sect3 renderas="sect4" id="handle-as-image">
4614 <title>handle-as-image</title>
4618 <term>Typical use:</term>
4620 <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>
4625 <term>Effect:</term>
4628 This action alone doesn't do anything noticeable. It just marks URLs as images.
4629 If the <literal><link linkend="block">block</link></literal> action <emphasis>also applies</emphasis>,
4630 the presence or absence of this mark decides whether an HTML <quote>blocked</quote>
4631 page, or a replacement image (as determined by the <literal><link
4632 linkend="set-image-blocker">set-image-blocker</link></literal> action) will be sent to the
4633 client as a substitute for the blocked content.
4640 <!-- Boolean, Parameterized, Multi-value -->
4642 <para>Boolean.</para>
4647 <term>Parameter:</term>
4659 The below generic example section is actually part of <filename>default.action</filename>.
4660 It marks all URLs with well-known image file name extensions as images and should
4664 Users will probably only want to use the handle-as-image action in conjunction with
4665 <literal><link linkend="block">block</link></literal>, to block sources of banners, whose URLs don't
4666 reflect the file type, like in the second example section.
4669 Note that you cannot treat HTML pages as images in most cases. For instance, (in-line) ad
4670 frames require an HTML page to be sent, or they won't display properly.
4671 Forcing <literal>handle-as-image</literal> in this situation will not replace the
4672 ad frame with an image, but lead to error messages.
4678 <term>Example usage (sections):</term>
4680 <screen># Generic image extensions:
4683 /.*\.(gif|jpg|jpeg|png|bmp|ico)$
4685 # These don't look like images, but they're banners and should be
4686 # blocked as images:
4688 {+block{Nasty banners.} +handle-as-image}
4689 nasty-banner-server.example.com/junk.cgi\?output=trash
4697 <!-- ~~~~~ New section ~~~~~ -->
4698 <sect3 renderas="sect4" id="hide-accept-language">
4699 <title>hide-accept-language</title>
4705 <term>Typical use:</term>
4707 <para>Pretend to use different language settings.</para>
4712 <term>Effect:</term>
4715 Deletes or replaces the <quote>Accept-Language:</quote> HTTP header in client requests.
4722 <!-- Boolean, Parameterized, Multi-value -->
4724 <para>Parameterized.</para>
4729 <term>Parameter:</term>
4732 Keyword: <quote>block</quote>, or any user defined value.
4741 Faking the browser's language settings can be useful to make a
4742 foreign User-Agent set with
4743 <literal><link linkend="hide-user-agent">hide-user-agent</link></literal>
4747 However some sites with content in different languages check the
4748 <quote>Accept-Language:</quote> to decide which one to take by default.
4749 Sometimes it isn't possible to later switch to another language without
4750 changing the <quote>Accept-Language:</quote> header first.
4753 Therefore it's a good idea to either only change the
4754 <quote>Accept-Language:</quote> header to languages you understand,
4755 or to languages that aren't wide spread.
4758 Before setting the <quote>Accept-Language:</quote> header
4759 to a rare language, you should consider that it helps to
4760 make your requests unique and thus easier to trace.
4761 If you don't plan to change this header frequently,
4762 you should stick to a common language.
4768 <term>Example usage (section):</term>
4770 <screen># Pretend to use Canadian language settings.
4771 {+hide-accept-language{en-ca} \
4772 +hide-user-agent{Mozilla/5.0 (X11; U; OpenBSD i386; en-CA; rv:1.8.0.4) Gecko/20060628 Firefox/1.5.0.4} \
4782 <!-- ~~~~~ New section ~~~~~ -->
4783 <sect3 renderas="sect4" id="hide-content-disposition">
4784 <title>hide-content-disposition</title>
4790 <term>Typical use:</term>
4792 <para>Prevent download menus for content you prefer to view inside the browser.</para>
4797 <term>Effect:</term>
4800 Deletes or replaces the <quote>Content-Disposition:</quote> HTTP header set by some servers.
4807 <!-- Boolean, Parameterized, Multi-value -->
4809 <para>Parameterized.</para>
4814 <term>Parameter:</term>
4817 Keyword: <quote>block</quote>, or any user defined value.
4826 Some servers set the <quote>Content-Disposition:</quote> HTTP header for
4827 documents they assume you want to save locally before viewing them.
4828 The <quote>Content-Disposition:</quote> header contains the file name
4829 the browser is supposed to use by default.
4832 In most browsers that understand this header, it makes it impossible to
4833 <emphasis>just view</emphasis> the document, without downloading it first,
4834 even if it's just a simple text file or an image.
4837 Removing the <quote>Content-Disposition:</quote> header helps
4838 to prevent this annoyance, but some browsers additionally check the
4839 <quote>Content-Type:</quote> header, before they decide if they can
4840 display a document without saving it first. In these cases, you have
4841 to change this header as well, before the browser stops displaying
4845 It is also possible to change the server's file name suggestion
4846 to another one, but in most cases it isn't worth the time to set
4850 This action will probably be removed in the future,
4851 use server-header filters instead.
4857 <term>Example usage:</term>
4859 <screen># Disarm the download link in Sourceforge's patch tracker
4861 +content-type-overwrite{text/plain}\
4862 +hide-content-disposition{block} }
4863 .sourceforge.net/tracker/download\.php</screen>
4870 <!-- ~~~~~ New section ~~~~~ -->
4871 <sect3 renderas="sect4" id="hide-if-modified-since">
4872 <title>hide-if-modified-since</title>
4878 <term>Typical use:</term>
4880 <para>Prevent yet another way to track the user's steps between sessions.</para>
4885 <term>Effect:</term>
4888 Deletes the <quote>If-Modified-Since:</quote> HTTP client header or modifies its value.
4895 <!-- Boolean, Parameterized, Multi-value -->
4897 <para>Parameterized.</para>
4902 <term>Parameter:</term>
4905 Keyword: <quote>block</quote>, or a user defined value that specifies a range of hours.
4914 Removing this header is useful for filter testing, where you want to force a real
4915 reload instead of getting status code <quote>304</quote>, which would cause the
4916 browser to use a cached copy of the page.
4919 Instead of removing the header, <literal>hide-if-modified-since</literal> can
4920 also add or subtract a random amount of time to/from the header's value.
4921 You specify a range of minutes where the random factor should be chosen from and
4922 <application>Privoxy</application> does the rest. A negative value means
4923 subtracting, a positive value adding.
4926 Randomizing the value of the <quote>If-Modified-Since:</quote> makes
4927 it less likely that the server can use the time as a cookie replacement,
4928 but you will run into caching problems if the random range is too high.
4931 It is a good idea to only use a small negative value and let
4932 <literal><link linkend="overwrite-last-modified">overwrite-last-modified</link></literal>
4933 handle the greater changes.
4936 It is also recommended to use this action together with
4937 <literal><link linkend="crunch-if-none-match">crunch-if-none-match</link></literal>,
4938 otherwise it's more or less pointless.
4944 <term>Example usage (section):</term>
4946 <screen># Let the browser revalidate but make tracking based on the time less likely.
4947 {+hide-if-modified-since{-60} \
4948 +overwrite-last-modified{randomize} \
4949 +crunch-if-none-match}
4957 <!-- ~~~~~ New section ~~~~~ -->
4958 <sect3 renderas="sect4" id="hide-from-header">
4959 <title>hide-from-header</title>
4963 <term>Typical use:</term>
4965 <para>Keep your (old and ill) browser from telling web servers your email address</para>
4970 <term>Effect:</term>
4973 Deletes any existing <quote>From:</quote> HTTP header, or replaces it with the
4981 <!-- Boolean, Parameterized, Multi-value -->
4983 <para>Parameterized.</para>
4988 <term>Parameter:</term>
4991 Keyword: <quote>block</quote>, or any user defined value.
5000 The keyword <quote>block</quote> will completely remove the header
5001 (not to be confused with the <literal><link linkend="block">block</link></literal>
5005 Alternately, you can specify any value you prefer to be sent to the web
5006 server. If you do, it is a matter of fairness not to use any address that
5007 is actually used by a real person.
5010 This action is rarely needed, as modern web browsers don't send
5011 <quote>From:</quote> headers anymore.
5017 <term>Example usage:</term>
5019 <screen>+hide-from-header{block}</screen>
5021 <screen>+hide-from-header{spam-me-senseless@sittingduck.example.com}</screen>
5028 <!-- ~~~~~ New section ~~~~~ -->
5029 <sect3 renderas="sect4" id="hide-referrer">
5030 <title>hide-referrer</title>
5031 <anchor id="hide-referer">
5034 <term>Typical use:</term>
5036 <para>Conceal which link you followed to get to a particular site</para>
5041 <term>Effect:</term>
5044 Deletes the <quote>Referer:</quote> (sic) HTTP header from the client request,
5045 or replaces it with a forged one.
5052 <!-- Boolean, Parameterized, Multi-value -->
5054 <para>Parameterized.</para>
5059 <term>Parameter:</term>
5063 <para><quote>conditional-block</quote> to delete the header completely if the host has changed.</para>
5066 <para><quote>conditional-forge</quote> to forge the header if the host has changed.</para>
5069 <para><quote>block</quote> to delete the header unconditionally.</para>
5072 <para><quote>forge</quote> to pretend to be coming from the homepage of the server we are talking to.</para>
5075 <para>Any other string to set a user defined referrer.</para>
5085 <literal>conditional-block</literal> is the only parameter,
5086 that isn't easily detected in the server's log file. If it blocks the
5087 referrer, the request will look like the visitor used a bookmark or
5088 typed in the address directly.
5091 Leaving the referrer unmodified for requests on the same host
5092 allows the server owner to see the visitor's <quote>click path</quote>,
5093 but in most cases she could also get that information by comparing
5094 other parts of the log file: for example the User-Agent if it isn't
5095 a very common one, or the user's IP address if it doesn't change between
5099 Always blocking the referrer, or using a custom one, can lead to
5100 failures on servers that check the referrer before they answer any
5101 requests, in an attempt to prevent their content from being
5102 embedded or linked to elsewhere.
5105 Both <literal>conditional-block</literal> and <literal>forge</literal>
5106 will work with referrer checks, as long as content and valid referring page
5107 are on the same host. Most of the time that's the case.
5110 <literal>hide-referer</literal> is an alternate spelling of
5111 <literal>hide-referrer</literal> and the two can be can be freely
5112 substituted with each other. (<quote>referrer</quote> is the
5113 correct English spelling, however the HTTP specification has a bug - it
5114 requires it to be spelled as <quote>referer</quote>.)
5120 <term>Example usage:</term>
5122 <screen>+hide-referrer{forge}</screen>
5124 <screen>+hide-referrer{http://www.yahoo.com/}</screen>
5131 <!-- ~~~~~ New section ~~~~~ -->
5132 <sect3 renderas="sect4" id="hide-user-agent">
5133 <title>hide-user-agent</title>
5137 <term>Typical use:</term>
5139 <para>Try to conceal your type of browser and client operating system</para>
5144 <term>Effect:</term>
5147 Replaces the value of the <quote>User-Agent:</quote> HTTP header
5148 in client requests with the specified value.
5155 <!-- Boolean, Parameterized, Multi-value -->
5157 <para>Parameterized.</para>
5162 <term>Parameter:</term>
5165 Any user-defined string.
5175 This can lead to problems on web sites that depend on looking at this header in
5176 order to customize their content for different browsers (which, by the
5177 way, is <emphasis>NOT</emphasis> the right thing to do: good web sites
5178 work browser-independently).
5182 Using this action in multi-user setups or wherever different types of
5183 browsers will access the same <application>Privoxy</application> is
5184 <emphasis>not recommended</emphasis>. In single-user, single-browser
5185 setups, you might use it to delete your OS version information from
5186 the headers, because it is an invitation to exploit known bugs for your
5187 OS. It is also occasionally useful to forge this in order to access
5188 sites that won't let you in otherwise (though there may be a good
5189 reason in some cases).
5192 More information on known user-agent strings can be found at
5193 <ulink url="http://www.user-agents.org/">http://www.user-agents.org/</ulink>
5195 <ulink url="https://en.wikipedia.org/wiki/User_agent">http://en.wikipedia.org/wiki/User_agent</ulink>.
5201 <term>Example usage:</term>
5203 <screen>+hide-user-agent{Mozilla/5.0 (X11; ElectroBSD i386; rv:78.0) Gecko/20100101 Firefox/78.0}</screen>
5210 <!-- ~~~~~ New section ~~~~~ -->
5211 <sect3 renderas="sect4" id="https-inspection">
5212 <title>https-inspection</title>
5216 <term>Typical use:</term>
5218 <para>Filter encrypted requests and responses</para>
5223 <term>Effect:</term>
5226 Encrypted requests are decrypted, filtered and forwarded encrypted.
5233 <!-- boolean, parameterized, Multi-value -->
5235 <para>Boolean.</para>
5240 <term>Parameter:</term>
5252 This action allows &my-app; to filter encrypted requests and responses.
5253 For this to work &my-app; has to generate a certificate and send it
5254 to the client which has to accept it.
5257 Before this works the directives in the
5258 <literal><ulink url="config.html#HTTPS-INSPECTION-DIRECTIVES">HTTPS inspection section</ulink></literal>
5259 of the config file have to be configured.
5262 Note that the action has to be enabled based on the CONNECT
5263 request which doesn't contain a path. Enabling it based on
5264 a pattern with path doesn't work as the path is only seen
5265 by &my-app; if the action is already enabled.
5268 This is an experimental feature.
5274 <term>Example usage (section):</term>
5276 <screen>{+https-inspection}
5277 www.example.com</screen>
5285 <!-- ~~~~~ New section ~~~~~ -->
5286 <sect3 renderas="sect4" id="ignore-certificate-errors">
5287 <title>ignore-certificate-errors</title>
5291 <term>Typical use:</term>
5293 <para>Filter encrypted requests and responses without verifying the certificate</para>
5298 <term>Effect:</term>
5301 Encrypted requests are forwarded to sites without verifying the certificate.
5308 <!-- Boolean, Parameterized, Multi-value -->
5310 <para>Boolean.</para>
5315 <term>Parameter:</term>
5328 <link linkend="HTTPS-INSPECTION"><quote>+https-inspection</quote></link>
5329 action is used &my-app; by default verifies that the remote site uses a valid
5333 If the certificate can't be validated by &my-app; the connection is aborted.
5336 This action disables the certificate check so requests to sites
5337 with certificates that can't be validated are allowed.
5340 Note that enabling this action allows Man-in-the-middle attacks.
5346 <term>Example usage:</term>
5349 {+ignore-certificate-errors}
5358 <!-- ~~~~~ New section ~~~~~ -->
5359 <sect3 renderas="sect4" id="limit-connect">
5360 <title>limit-connect</title>
5364 <term>Typical use:</term>
5366 <para>Prevent abuse of <application>Privoxy</application> as a TCP proxy relay or disable SSL for untrusted sites</para>
5371 <term>Effect:</term>
5374 Specifies to which ports HTTP CONNECT requests are allowable.
5381 <!-- Boolean, Parameterized, Multi-value -->
5383 <para>Parameterized.</para>
5388 <term>Parameter:</term>
5391 A comma-separated list of ports or port ranges (the latter using dashes, with the minimum
5392 defaulting to 0 and the maximum to 65K).
5401 By default, i.e. if no <literal>limit-connect</literal> action applies,
5402 <application>Privoxy</application> allows HTTP CONNECT requests to all
5403 ports. Use <literal>limit-connect</literal> if fine-grained control
5404 is desired for some or all destinations.
5407 The CONNECT methods exists in HTTP to allow access to secure websites
5408 (<quote>https://</quote> URLs) through proxies. It works very simply:
5409 the proxy connects to the server on the specified port, and then
5410 short-circuits its connections to the client and to the remote server.
5411 This means CONNECT-enabled proxies can be used as TCP relays very easily.
5414 <application>Privoxy</application> relays HTTPS traffic without seeing
5415 the decoded content. Websites can leverage this limitation to circumvent &my-app;'s
5416 filters. By specifying an invalid port range you can disable HTTPS entirely.
5422 <term>Example usages:</term>
5424 <!-- I had trouble getting the spacing to look right in my browser -->
5425 <!-- I probably have the wrong font setup, bollocks. -->
5426 <!-- Apparently the emphasis tag uses a proportional font no matter what -->
5427 <screen>+limit-connect{443} # Port 443 is OK.
5428 +limit-connect{80,443} # Ports 80 and 443 are OK.
5429 +limit-connect{-3, 7, 20-100, 500-} # Ports less than 3, 7, 20 to 100 and above 500 are OK.
5430 +limit-connect{-} # All ports are OK
5431 +limit-connect{,} # No HTTPS/SSL traffic is allowed</screen>
5438 <!-- ~~~~~ New section ~~~~~ -->
5439 <sect3 renderas="sect4" id="limit-cookie-lifetime">
5440 <title>limit-cookie-lifetime</title>
5444 <term>Typical use:</term>
5446 <para>Limit the lifetime of HTTP cookies to a couple of minutes or hours.</para>
5451 <term>Effect:</term>
5454 Overwrites the expires field in Set-Cookie server headers if it's above the specified limit.
5461 <!-- Boolean, Parameterized, Multi-value -->
5463 <para>Parameterized.</para>
5468 <term>Parameter:</term>
5471 The lifetime limit in minutes, or 0.
5480 This action reduces the lifetime of HTTP cookies coming from the
5481 server to the specified number of minutes, starting from the time
5482 the cookie passes Privoxy.
5485 Cookies with a lifetime below the limit are not modified.
5486 The lifetime of session cookies is set to the specified limit.
5489 The effect of this action depends on the server.
5492 In case of servers which refresh their cookies with each response
5493 (or at least frequently), the lifetime limit set by this action
5495 Thus, a session associated with the cookie continues to work with
5496 this action enabled, as long as a new request is made before the
5497 last limit set is reached.
5500 However, some servers send their cookies once, with a lifetime of several
5501 years (the year 2037 is a popular choice), and do not refresh them
5502 until a certain event in the future, for example the user logging out.
5503 In this case this action may limit the absolute lifetime of the session,
5504 even if requests are made frequently.
5507 If the parameter is <quote>0</quote>, this action behaves like
5508 <literal><link linkend="session-cookies-only">session-cookies-only</link></literal>.
5514 <term>Example usages:</term>
5516 <screen>+limit-cookie-lifetime{60}</screen>
5522 <!-- ~~~~~ New section ~~~~~ -->
5523 <sect3 renderas="sect4" id="prevent-compression">
5524 <title>prevent-compression</title>
5528 <term>Typical use:</term>
5531 Ensure that servers send the content uncompressed, so it can be
5532 passed through <literal><link linkend="filter">filter</link></literal>s.
5538 <term>Effect:</term>
5541 Removes the Accept-Encoding header which can be used to ask for compressed transfer.
5548 <!-- Boolean, Parameterized, Multi-value -->
5550 <para>Boolean.</para>
5555 <term>Parameter:</term>
5567 More and more websites send their content compressed by default, which
5568 is generally a good idea and saves bandwidth. But the <literal><link
5569 linkend="filter">filter</link></literal> and
5570 <literal><link linkend="deanimate-gifs">deanimate-gifs</link></literal>
5571 actions need access to the uncompressed data.
5574 When compiled with zlib support (available since &my-app; 3.0.7), content that should be
5575 filtered is decompressed on-the-fly and you don't have to worry about this action.
5576 If you are using an older &my-app; version, or one that hasn't been compiled with zlib
5577 support, this action can be used to convince the server to send the content uncompressed.
5580 Most text-based instances compress very well, the size is seldom decreased by less than 50%,
5581 for markup-heavy instances like news feeds saving more than 90% of the original size isn't
5585 Not using compression will therefore slow down the transfer, and you should only
5586 enable this action if you really need it. As of &my-app; 3.0.7 it's disabled in all
5587 predefined action settings.
5590 Note that some (rare) ill-configured sites don't handle requests for uncompressed
5591 documents correctly. Broken PHP applications tend to send an empty document body,
5592 some IIS versions only send the beginning of the content and some content delivery
5593 networks let the connection time out.
5594 If you enable <literal>prevent-compression</literal> per default, you might
5595 want to add exceptions for those sites. See the example for how to do that.
5601 <term>Example usage (sections):</term>
5604 # Selectively turn off compression, and enable a filter
5606 { +filter{tiny-textforms} +prevent-compression }
5607 # Match only these sites
5612 # Or instead, we could set a universal default:
5614 { +prevent-compression }
5617 # Then maybe make exceptions for broken sites:
5619 { -prevent-compression }
5620 .compusa.com/</screen>
5628 <!-- ~~~~~ New section ~~~~~ -->
5629 <sect3 renderas="sect4" id="overwrite-last-modified">
5630 <title>overwrite-last-modified</title>
5636 <term>Typical use:</term>
5638 <para>Prevent yet another way to track the user's steps between sessions.</para>
5643 <term>Effect:</term>
5646 Deletes the <quote>Last-Modified:</quote> HTTP server header or modifies its value.
5653 <!-- Boolean, Parameterized, Multi-value -->
5655 <para>Parameterized.</para>
5660 <term>Parameter:</term>
5663 One of the keywords: <quote>block</quote>, <quote>reset-to-request-time</quote>
5664 and <quote>randomize</quote>
5673 Removing the <quote>Last-Modified:</quote> header is useful for filter
5674 testing, where you want to force a real reload instead of getting status
5675 code <quote>304</quote>, which would cause the browser to reuse the old
5676 version of the page.
5679 The <quote>randomize</quote> option overwrites the value of the
5680 <quote>Last-Modified:</quote> header with a randomly chosen time
5681 between the original value and the current time. In theory the server
5682 could send each document with a different <quote>Last-Modified:</quote>
5683 header to track visits without using cookies. <quote>Randomize</quote>
5684 makes it impossible and the browser can still revalidate cached documents.
5687 <quote>reset-to-request-time</quote> overwrites the value of the
5688 <quote>Last-Modified:</quote> header with the current time. You could use
5689 this option together with
5690 <literal><link linkend="hide-if-modified-since">hide-if-modified-since</link></literal>
5691 to further customize your random range.
5694 The preferred parameter here is <quote>randomize</quote>. It is safe
5695 to use, as long as the time settings are more or less correct.
5696 If the server sets the <quote>Last-Modified:</quote> header to the time
5697 of the request, the random range becomes zero and the value stays the same.
5698 Therefore you should later randomize it a second time with
5699 <literal><link linkend="hide-if-modified-since">hided-if-modified-since</link></literal>,
5703 It is also recommended to use this action together with
5704 <literal><link linkend="crunch-if-none-match">crunch-if-none-match</link></literal>.
5710 <term>Example usage:</term>
5712 <screen># Let the browser revalidate without being tracked across sessions
5713 { +hide-if-modified-since{-60} \
5714 +overwrite-last-modified{randomize} \
5715 +crunch-if-none-match}
5723 <!-- ~~~~~ New section ~~~~~ -->
5724 <sect3 renderas="sect4" id="redirect">
5725 <title>redirect</title>
5731 <term>Typical use:</term>
5734 Redirect requests to other sites.
5740 <term>Effect:</term>
5743 Convinces the browser that the requested document has been moved
5744 to another location and the browser should get it from there.
5751 <!-- Boolean, Parameterized, Multi-value -->
5753 <para>Parameterized</para>
5758 <term>Parameter:</term>
5761 An absolute URL or a single pcrs command.
5770 Requests to which this action applies are answered with a
5771 HTTP redirect to URLs of your choosing. The new URL is
5772 either provided as parameter, or derived by applying a
5773 single pcrs command to the original URL.
5776 The syntax for pcrs commands is documented in the
5777 <link linkend="filter-file">filter file</link> section.
5780 Requests can't be blocked and redirected at the same time,
5781 applying this action together with
5782 <literal><link linkend="block">block</link></literal>
5783 is a configuration error. Currently the request is blocked
5784 and an error message logged, the behavior may change in the
5785 future and result in Privoxy rejecting the action file.
5788 This action can be combined with
5789 <literal><link linkend="fast-redirects">fast-redirects{check-decoded-url}</link></literal>
5790 to redirect to a decoded version of a rewritten URL.
5793 Use this action carefully, make sure not to create redirection loops
5794 and be aware that using your own redirects might make it
5795 possible to fingerprint your requests.
5798 In case of problems with your redirects, or simply to watch
5799 them working, enable <link linkend="DEBUG">debug 128</link>.
5805 <term>Example usages:</term>
5807 <screen># Replace example.com's style sheet with another one
5808 { +redirect{http://localhost/css-replacements/example.com.css} }
5809 example.com/stylesheet\.css
5811 # Create a short, easy to remember nickname for a favorite site
5812 # (relies on the browser to accept and forward invalid URLs to &my-app;)
5813 { +redirect{https://www.privoxy.org/user-manual/actions-file.html} }
5816 # Always use the expanded view for Undeadly.org articles
5817 # (Note the $ at the end of the URL pattern to make sure
5818 # the request for the rewritten URL isn't redirected as well)
5819 {+redirect{s@$@&mode=expanded@}}
5820 undeadly.org/cgi\?action=article&sid=\d*$
5822 # Redirect Google search requests to MSN
5823 {+redirect{s@^http://[^/]*/search\?q=([^&]*).*@http://search.msn.com/results.aspx?q=$1@}}
5826 # Redirect MSN search requests to Yahoo
5827 {+redirect{s@^http://[^/]*/results\.aspx\?q=([^&]*).*@http://search.yahoo.com/search?p=$1@}}
5828 search.msn.com//results\.aspx\?q=
5830 # Redirect http://example.com/&bla=fasel&toChange=foo (and any other value but "bar")
5831 # to http://example.com/&bla=fasel&toChange=bar
5833 # The URL pattern makes sure that the following request isn't redirected again.
5834 {+redirect{s@toChange=[^&]+@toChange=bar@}}
5835 example.com/.*toChange=(?!bar)
5837 # Add a shortcut to look up illumos bugs
5838 {+redirect{s@^http://i([0-9]+)/.*@https://www.illumos.org/issues/$1@}}
5839 # Redirected URL = http://i4974/
5840 # Redirect Destination = https://www.illumos.org/issues/4974
5841 i[0-9][0-9][0-9][0-9]*/
5843 # Redirect requests for the old Tor Hidden Service of the Privoxy website to the new one
5844 {+redirect{s@^http://jvauzb4sb3bwlsnc.onion/@http://l3tczdiiwoo63iwxty4lhs6p7eaxop5micbn7vbliydgv63x5zrrrfyd.onion/@}}
5845 jvauzb4sb3bwlsnc.onion/
5847 # Redirect remote requests for this manual
5848 # to the local version delivered by Privoxy
5849 {+redirect{s@^http://www@http://config@}}
5850 www.privoxy.org/user-manual/</screen>
5858 <!-- ~~~~~ New section ~~~~~ -->
5859 <sect3 renderas="sect4" id="server-header-filter">
5860 <title>server-header-filter</title>
5864 <term>Typical use:</term>
5867 Rewrite or remove single server headers.
5873 <term>Effect:</term>
5876 All server headers to which this action applies are filtered on-the-fly
5877 through the specified regular expression based substitutions.
5884 <!-- boolean, parameterized, Multi-value -->
5886 <para>Multi-value.</para>
5891 <term>Parameter:</term>
5894 The name of a server-header filter, as defined in one of the
5895 <link linkend="filter-file">filter files</link>.
5904 Server-header filters are applied to each header on its own, not to
5905 all at once. This makes it easier to diagnose problems, but on the downside
5906 you can't write filters that only change header x if header y's value is z.
5907 You can do that by using tags though.
5910 Server-header filters are executed after the other header actions have finished
5911 and use their output as input.
5914 Please refer to the <link linkend="filter-file">filter file chapter</link>
5915 to learn which server-header filters are available by default, and how to
5922 <term>Example usage (section):</term>
5925 {+server-header-filter{html-to-xml}}
5926 example.org/xml-instance-that-is-delivered-as-html
5928 {+server-header-filter{xml-to-html}}
5929 example.org/instance-that-is-delivered-as-xml-but-is-not
5938 <!-- ~~~~~ New section ~~~~~ -->
5939 <sect3 renderas="sect4" id="server-header-tagger">
5940 <title>server-header-tagger</title>
5944 <term>Typical use:</term>
5947 Enable or disable filters based on the Content-Type header.
5953 <term>Effect:</term>
5956 Server headers to which this action applies are filtered on-the-fly through
5957 the specified regular expression based substitutions, the result is used as
5965 <!-- boolean, parameterized, Multi-value -->
5967 <para>Multi-value.</para>
5972 <term>Parameter:</term>
5975 The name of a server-header tagger, as defined in one of the
5976 <link linkend="filter-file">filter files</link>.
5985 Server-header taggers are applied to each header on its own,
5986 and as the header isn't modified, each tagger <quote>sees</quote>
5990 Server-header taggers are executed before all other header actions
5991 that modify server headers. Their tags can be used to control
5992 all of the other server-header actions, the content filters
5993 and the crunch actions (<link linkend="redirect">redirect</link>
5994 and <link linkend="block">block</link>).
5997 Obviously crunching based on tags created by server-header taggers
5998 doesn't prevent the request from showing up in the server's log file.
6005 <term>Example usage (section):</term>
6008 # Tag every request with the content type declared by the server
6009 {+server-header-tagger{content-type}}
6012 # If the response has a tag starting with 'image/' enable an external
6013 # filter that only applies to images.
6015 # Note that the filter is not available by default, it's just a
6016 # <literal><link linkend="external-filter-syntax">silly example</link></literal>.
6017 {+external-filter{rotate-image} +force-text-mode}
6027 <!-- ~~~~~ New section ~~~~~ -->
6028 <sect3 renderas="sect4" id="suppress-tag">
6029 <title>suppress-tag</title>
6033 <term>Typical use:</term>
6036 Suppress client or server tag.
6042 <term>Effect:</term>
6045 Server or client tags to which this action applies are not added to the request,
6046 thus making all actions that are specific to these request tags inactive.
6053 <!-- boolean, parameterized, Multi-value -->
6055 <para>Multi-value.</para>
6060 <term>Parameter:</term>
6063 The result tag of a server-header or client-header tagger, as defined in one of the
6064 <link linkend="filter-file">filter files</link>.
6070 <term>Example usage (section):</term>
6073 # Suppress tag produced by range-requests client-header tagger for requests coming from address 10.0.0.1
6074 {+suppress-tag{RANGE-REQUEST}}
6075 TAG:^IP-ADDRESS: 10\.0\.0\.1$
6084 <!-- ~~~~~ New section ~~~~~ -->
6085 <sect3 renderas="sect4" id="session-cookies-only">
6086 <title>session-cookies-only</title>
6090 <term>Typical use:</term>
6093 Allow only temporary <quote>session</quote> cookies (for the current
6094 browser session <emphasis>only</emphasis>).
6100 <term>Effect:</term>
6103 Deletes the <quote>expires</quote> field from <quote>Set-Cookie:</quote>
6104 server headers. Most browsers will not store such cookies permanently and
6105 forget them in between sessions.
6112 <!-- Boolean, Parameterized, Multi-value -->
6114 <para>Boolean.</para>
6119 <term>Parameter:</term>
6131 This is less strict than <literal><link linkend="crunch-incoming-cookies">crunch-incoming-cookies</link></literal> /
6132 <literal><link linkend="crunch-outgoing-cookies">crunch-outgoing-cookies</link></literal> and allows you to browse
6133 websites that insist or rely on setting cookies, without compromising your privacy too badly.
6136 Most browsers will not permanently store cookies that have been processed by
6137 <literal>session-cookies-only</literal> and will forget about them between sessions.
6138 This makes profiling cookies useless, but won't break sites which require cookies so
6139 that you can log in for transactions. This is generally turned on for all
6140 sites, and is the recommended setting.
6143 It makes <emphasis>no sense at all</emphasis> to use <literal>session-cookies-only</literal>
6144 together with <literal><link linkend="crunch-incoming-cookies">crunch-incoming-cookies</link></literal> or
6145 <literal><link linkend="crunch-outgoing-cookies">crunch-outgoing-cookies</link></literal>. If you do, cookies
6146 will be plainly killed.
6149 Note that it is up to the browser how it handles such cookies without an <quote>expires</quote>
6150 field. If you use an exotic browser, you might want to try it out to be sure.
6153 This setting also has no effect on cookies that may have been stored
6154 previously by the browser before starting <application>Privoxy</application>.
6155 These would have to be removed manually.
6158 <application>Privoxy</application> also uses
6159 the <link linkend="filter-content-cookies">content-cookies filter</link>
6160 to block some types of cookies. Content cookies are not effected by
6161 <literal>session-cookies-only</literal>.
6167 <term>Example usage:</term>
6169 <screen>+session-cookies-only</screen>
6176 <!-- ~~~~~ New section ~~~~~ -->
6177 <sect3 renderas="sect4" id="set-image-blocker">
6178 <title>set-image-blocker</title>
6182 <term>Typical use:</term>
6184 <para>Choose the replacement for blocked images</para>
6189 <term>Effect:</term>
6192 This action alone doesn't do anything noticeable. If <emphasis>both</emphasis>
6193 <literal><link linkend="block">block</link></literal> <emphasis>and</emphasis> <literal><link
6194 linkend="handle-as-image">handle-as-image</link></literal> <emphasis>also</emphasis>
6195 apply, i.e. if the request is to be blocked as an image,
6196 <emphasis>then</emphasis> the parameter of this action decides what will be
6197 sent as a replacement.
6204 <!-- Boolean, Parameterized, Multi-value -->
6206 <para>Parameterized.</para>
6211 <term>Parameter:</term>
6216 <quote>pattern</quote> to send a built-in checkerboard pattern image. The image is visually
6217 decent, scales very well, and makes it obvious where banners were busted.
6222 <quote>blank</quote> to send a built-in transparent image. This makes banners disappear
6223 completely, but makes it hard to detect where <application>Privoxy</application> has blocked
6224 images on a given page and complicates troubleshooting if <application>Privoxy</application>
6225 has blocked innocent images, like navigation icons.
6230 <quote><replaceable class="parameter">target-url</replaceable></quote> to
6231 send a redirect to <replaceable class="parameter">target-url</replaceable>. You can redirect
6232 to any image anywhere, even in your local filesystem via <quote>file:///</quote> URL.
6233 (But note that not all browsers support redirecting to a local file system).
6236 A good application of redirects is to use special <application>Privoxy</application>-built-in
6237 URLs, which send the built-in images, as <replaceable class="parameter">target-url</replaceable>.
6238 This has the same visual effect as specifying <quote>blank</quote> or <quote>pattern</quote> in
6239 the first place, but enables your browser to cache the replacement image, instead of requesting
6240 it over and over again.
6251 The URLs for the built-in images are <quote>http://config.privoxy.org/send-banner?type=<replaceable
6252 class="parameter">type</replaceable></quote>, where <replaceable class="parameter">type</replaceable> is
6253 either <quote>blank</quote> or <quote>pattern</quote>.
6256 There is a third (advanced) type, called <quote>auto</quote>. It is <emphasis>NOT</emphasis> to be
6257 used in <literal>set-image-blocker</literal>, but meant for use from <link linkend="filter-file">filters</link>.
6258 Auto will select the type of image that would have applied to the referring page, had it been an image.
6264 <term>Example usage:</term>
6269 <screen>+set-image-blocker{pattern}</screen>
6271 Redirect to the BSD daemon:
6273 <screen>+set-image-blocker{http://www.freebsd.org/gifs/dae_up3.gif}</screen>
6275 Redirect to the built-in pattern for better caching:
6277 <screen>+set-image-blocker{http://config.privoxy.org/send-banner?type=pattern}</screen>
6284 <!-- ~~~~~ New section ~~~~~ -->
6285 <sect3 id="summary">
6286 <title>Summary</title>
6288 Note that many of these actions have the potential to cause a page to
6289 misbehave, possibly even not to display at all. There are many ways
6290 a site designer may choose to design his site, and what HTTP header
6291 content, and other criteria, he may depend on. There is no way to have hard
6292 and fast rules for all sites. See the <link
6293 linkend="ACTIONSANAT">Appendix</link> for a brief example on troubleshooting
6299 <!-- ~~~~~ New section ~~~~~ -->
6300 <sect2 id="aliases">
6301 <title>Aliases</title>
6303 Custom <quote>actions</quote>, known to <application>Privoxy</application>
6304 as <quote>aliases</quote>, can be defined by combining other actions.
6305 These can in turn be invoked just like the built-in actions.
6306 Currently, an alias name can contain any character except space, tab,
6308 <quote>{</quote> and <quote>}</quote>, but we <emphasis>strongly
6309 recommend</emphasis> that you only use <quote>a</quote> to <quote>z</quote>,
6310 <quote>0</quote> to <quote>9</quote>, <quote>+</quote>, and <quote>-</quote>.
6311 Alias names are not case sensitive, and are not required to start with a
6312 <quote>+</quote> or <quote>-</quote> sign, since they are merely textually
6316 Aliases can be used throughout the actions file, but they <emphasis>must be
6317 defined in a special section at the top of the file!</emphasis>
6318 And there can only be one such section per actions file. Each actions file may
6319 have its own alias section, and the aliases defined in it are only visible
6323 There are two main reasons to use aliases: One is to save typing for frequently
6324 used combinations of actions, the other one is a gain in flexibility: If you
6325 decide once how you want to handle shops by defining an alias called
6326 <quote>shop</quote>, you can later change your policy on shops in
6327 <emphasis>one</emphasis> place, and your changes will take effect everywhere
6328 in the actions file where the <quote>shop</quote> alias is used. Calling aliases
6329 by their purpose also makes your actions files more readable.
6332 Currently, there is one big drawback to using aliases, though:
6333 <application>Privoxy</application>'s built-in web-based action file
6334 editor honors aliases when reading the actions files, but it expands
6335 them before writing. So the effects of your aliases are of course preserved,
6336 but the aliases themselves are lost when you edit sections that use aliases
6341 Now let's define some aliases...
6345 # Useful custom aliases we can use later.
6347 # Note the (required!) section header line and that this section
6348 # must be at the top of the actions file!
6352 # These aliases just save typing later:
6353 # (Note that some already use other aliases!)
6355 +crunch-all-cookies = +<link linkend="CRUNCH-INCOMING-COOKIES">crunch-incoming-cookies</link> +<link linkend="CRUNCH-OUTGOING-COOKIES">crunch-outgoing-cookies</link>
6356 -crunch-all-cookies = -<link linkend="CRUNCH-INCOMING-COOKIES">crunch-incoming-cookies</link> -<link linkend="CRUNCH-OUTGOING-COOKIES">crunch-outgoing-cookies</link>
6357 +block-as-image = +block{Blocked image.} +handle-as-image
6358 allow-all-cookies = -crunch-all-cookies -<link linkend="SESSION-COOKIES-ONLY">session-cookies-only</link> -<link linkend="FILTER-CONTENT-COOKIES">filter{content-cookies}</link>
6360 # These aliases define combinations of actions
6361 # that are useful for certain types of sites:
6363 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>
6365 shop = -crunch-all-cookies -<link linkend="FILTER-ALL-POPUPS">filter{all-popups}</link>
6367 # Short names for other aliases, for really lazy people ;-)
6369 c0 = +crunch-all-cookies
6370 c1 = -crunch-all-cookies</screen>
6373 ...and put them to use. These sections would appear in the lower part of an
6374 actions file and define exceptions to the default actions (as specified further
6375 up for the <quote>/</quote> pattern):
6379 # These sites are either very complex or very keen on
6380 # user data and require minimal interference to work:
6383 .office.microsoft.com
6384 .windowsupdate.microsoft.com
6385 # Gmail is really mail.google.com, not gmail.com
6389 # Allow cookies (for setting and retrieving your customer data)
6393 .worldpay.com # for quietpc.com
6396 # These shops require pop-ups:
6398 {-filter{all-popups} -filter{unsolicited-popups}}
6400 .overclockers.co.uk</screen>
6403 Aliases like <quote>shop</quote> and <quote>fragile</quote> are typically used for
6404 <quote>problem</quote> sites that require more than one action to be disabled
6405 in order to function properly.
6411 <!-- ~~~~~ New section ~~~~~ -->
6412 <sect2 id="act-examples">
6413 <title>Actions Files Tutorial</title>
6415 The above chapters have shown <link linkend="actions-file">which actions files
6416 there are and how they are organized</link>, how actions are <link
6417 linkend="actions">specified</link> and <link linkend="actions-apply">applied
6418 to URLs</link>, how <link linkend="af-patterns">patterns</link> work, and how to
6419 define and use <link linkend="aliases">aliases</link>. Now, let's look at an
6420 example <filename>match-all.action</filename>, <filename>default.action</filename>
6421 and <filename>user.action</filename> file and see how all these pieces come together:
6424 <sect3 id="match-all">
6425 <title>match-all.action</title>
6427 Remember <emphasis>all actions are disabled when matching starts</emphasis>,
6428 so we have to explicitly enable the ones we want.
6432 While the <filename>match-all.action</filename> file only contains a
6433 single section, it is probably the most important one. It has only one
6434 pattern, <quote><literal>/</literal></quote>, but this pattern
6435 <link linkend="af-patterns">matches all URLs</link>. Therefore, the set of
6436 actions used in this <quote>default</quote> section <emphasis>will
6437 be applied to all requests as a start</emphasis>. It can be partly or
6438 wholly overridden by other actions files like <filename>default.action</filename>
6439 and <filename>user.action</filename>, but it will still be largely responsible
6440 for your overall browsing experience.
6444 Again, at the start of matching, all actions are disabled, so there is
6445 no need to disable any actions here. (Remember: a <quote>+</quote>
6446 preceding the action name enables the action, a <quote>-</quote> disables!).
6447 Also note how this long line has been made more readable by splitting it into
6448 multiple lines with line continuation.
6453 +<link linkend="CHANGE-X-FORWARDED-FOR">change-x-forwarded-for{block}</link> \
6454 +<link linkend="HIDE-FROM-HEADER">hide-from-header{block}</link> \
6455 +<link linkend="SET-IMAGE-BLOCKER">set-image-blocker{pattern}</link> \
6461 The default behavior is now set.
6465 <sect3 id="default-action">
6466 <title>default.action</title>
6469 If you aren't a developer, there's no need for you to edit the
6470 <filename>default.action</filename> file. It is maintained by
6471 the &my-app; developers and if you disagree with some of the
6472 sections, you should overrule them in your <filename>user.action</filename>.
6476 Understanding the <filename>default.action</filename> file can
6477 help you with your <filename>user.action</filename>, though.
6481 The first section in this file is a special section for internal use
6482 that prevents older &my-app; versions from reading the file:
6486 ##########################################################################
6487 # Settings -- Don't change! For internal Privoxy use ONLY.
6488 ##########################################################################
6490 for-privoxy-version=3.0.11</screen>
6493 After that comes the (optional) alias section. We'll use the example
6494 section from the above <link linkend="aliases">chapter on aliases</link>,
6495 that also explains why and how aliases are used:
6499 ##########################################################################
6501 ##########################################################################
6504 # These aliases just save typing later:
6505 # (Note that some already use other aliases!)
6507 +crunch-all-cookies = +<link linkend="CRUNCH-INCOMING-COOKIES">crunch-incoming-cookies</link> +<link linkend="CRUNCH-OUTGOING-COOKIES">crunch-outgoing-cookies</link>
6508 -crunch-all-cookies = -<link linkend="CRUNCH-INCOMING-COOKIES">crunch-incoming-cookies</link> -<link linkend="CRUNCH-OUTGOING-COOKIES">crunch-outgoing-cookies</link>
6509 +block-as-image = +block{Blocked image.} +handle-as-image
6510 mercy-for-cookies = -crunch-all-cookies -<link linkend="SESSION-COOKIES-ONLY">session-cookies-only</link> -<link linkend="FILTER-CONTENT-COOKIES">filter{content-cookies}</link>
6512 # These aliases define combinations of actions
6513 # that are useful for certain types of sites:
6515 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>
6516 shop = -crunch-all-cookies -<link linkend="FILTER-ALL-POPUPS">filter{all-popups}</link></screen>
6519 The first of our specialized sections is concerned with <quote>fragile</quote>
6520 sites, i.e. sites that require minimum interference, because they are either
6521 very complex or very keen on tracking you (and have mechanisms in place that
6522 make them unusable for people who avoid being tracked). We will use
6523 our pre-defined <literal>fragile</literal> alias instead of stating the list
6524 of actions explicitly:
6528 ##########################################################################
6529 # Exceptions for sites that'll break under the default action set:
6530 ##########################################################################
6532 # "Fragile" Use a minimum set of actions for these sites (see alias above):
6535 .office.microsoft.com # surprise, surprise!
6536 .windowsupdate.microsoft.com
6537 mail.google.com</screen>
6540 Shopping sites are not as fragile, but they typically
6541 require cookies to log in, and pop-up windows for shopping
6542 carts or item details. Again, we'll use a pre-defined alias:
6550 .worldpay.com # for quietpc.com
6552 .scan.co.uk</screen>
6555 The <literal><link linkend="FAST-REDIRECTS">fast-redirects</link></literal>
6556 action, which may have been enabled in <filename>match-all.action</filename>,
6557 breaks some sites. So disable it for popular sites where we know it misbehaves:
6561 { -<link linkend="FAST-REDIRECTS">fast-redirects</link> }
6565 .altavista.com/.*(like|url|link):http
6566 .altavista.com/trans.*urltext=http
6567 .nytimes.com</screen>
6570 It is important that <application>Privoxy</application> knows which
6571 URLs belong to images, so that <emphasis>if</emphasis> they are to
6572 be blocked, a substitute image can be sent, rather than an HTML page.
6573 Contacting the remote site to find out is not an option, since it
6574 would destroy the loading time advantage of banner blocking, and it
6575 would feed the advertisers information about you. We can mark any
6576 URL as an image with the <literal><link
6577 linkend="handle-as-image">handle-as-image</link></literal> action,
6578 and marking all URLs that end in a known image file extension is a
6583 ##########################################################################
6585 ##########################################################################
6587 # Define which file types will be treated as images, in case they get
6588 # blocked further down this file:
6590 { +<link linkend="HANDLE-AS-IMAGE">handle-as-image</link> }
6591 /.*\.(gif|jpe?g|png|bmp|ico)$</screen>
6594 And then there are known banner sources. They often use scripts to
6595 generate the banners, so it won't be visible from the URL that the
6596 request is for an image. Hence we block them <emphasis>and</emphasis>
6597 mark them as images in one go, with the help of our
6598 <literal>+block-as-image</literal> alias defined above. (We could of
6599 course just as well use <literal>+<link linkend="block">block</link>
6600 +<link linkend="handle-as-image">handle-as-image</link></literal> here.)
6601 Remember that the type of the replacement image is chosen by the
6602 <literal><link linkend="set-image-blocker">set-image-blocker</link></literal>
6603 action. Since all URLs have matched the default section with its
6604 <literal>+<link linkend="set-image-blocker">set-image-blocker</link>{pattern}</literal>
6605 action before, it still applies and needn't be repeated:
6609 # Known ad generators:
6614 .ad.*.doubleclick.net
6615 .a.yimg.com/(?:(?!/i/).)*$
6616 .a[0-9].yimg.com/(?:(?!/i/).)*$
6621 One of the most important jobs of <application>Privoxy</application>
6622 is to block banners. Many of these can be <quote>blocked</quote>
6623 by the <literal><link linkend="filter">filter</link>{banners-by-size}</literal>
6624 action, which we enabled above, and which deletes the references to banner
6625 images from the pages while they are loaded, so the browser doesn't request
6626 them anymore, and hence they don't need to be blocked here. But this naturally
6627 doesn't catch all banners, and some people choose not to use filters, so we
6628 need a comprehensive list of patterns for banner URLs here, and apply the
6629 <literal><link linkend="block">block</link></literal> action to them.
6632 First comes many generic patterns, which do most of the work, by
6633 matching typical domain and path name components of banners. Then comes
6634 a list of individual patterns for specific sites, which is omitted here
6635 to keep the example short:
6639 ##########################################################################
6640 # Block these fine banners:
6641 ##########################################################################
6642 { <link linkend="BLOCK">+block{Banner ads.}</link> }
6650 /.*count(er)?\.(pl|cgi|exe|dll|asp|php[34]?)
6651 /(?:.*/)?(publicite|werbung|rekla(ma|me|am)|annonse|maino(kset|nta|s)?)/
6653 # Site-specific patterns (abbreviated):
6655 .hitbox.com</screen>
6658 It's quite remarkable how many advertisers actually call their banner
6659 servers ads.<replaceable>company</replaceable>.com, or call the directory
6660 in which the banners are stored literally <quote>banners</quote>. So the above
6661 generic patterns are surprisingly effective.
6664 But being very generic, they necessarily also catch URLs that we don't want
6665 to block. The pattern <literal>.*ads.</literal> e.g. catches
6666 <quote>nasty-<emphasis>ads</emphasis>.nasty-corp.com</quote> as intended,
6667 but also <quote>downlo<emphasis>ads</emphasis>.sourcefroge.net</quote> or
6668 <quote><emphasis>ads</emphasis>l.some-provider.net.</quote> So here come some
6669 well-known exceptions to the <literal>+<link linkend="BLOCK">block</link></literal>
6673 Note that these are exceptions to exceptions from the default! Consider the URL
6674 <quote>downloads.sourcefroge.net</quote>: Initially, all actions are deactivated,
6675 so it wouldn't get blocked. Then comes the defaults section, which matches the
6676 URL, but just deactivates the <literal><link linkend="BLOCK">block</link></literal>
6677 action once again. Then it matches <literal>.*ads.</literal>, an exception to the
6678 general non-blocking policy, and suddenly
6679 <literal><link linkend="BLOCK">+block</link></literal> applies. And now, it'll match
6680 <literal>.*loads.</literal>, where <literal><link linkend="BLOCK">-block</link></literal>
6681 applies, so (unless it matches <emphasis>again</emphasis> further down) it ends up
6682 with no <literal><link linkend="BLOCK">block</link></literal> action applying.
6686 ##########################################################################
6687 # Save some innocent victims of the above generic block patterns:
6688 ##########################################################################
6692 { -<link linkend="BLOCK">block</link> }
6693 adv[io]*. # (for advogato.org and advice.*)
6694 adsl. # (has nothing to do with ads)
6695 adobe. # (has nothing to do with ads either)
6696 ad[ud]*. # (adult.* and add.*)
6697 .edu # (universities don't host banners (yet!))
6698 .*loads. # (downloads, uploads etc)
6706 www.globalintersec.com/adv # (adv = advanced)
6707 www.ugu.com/sui/ugu/adv</screen>
6710 Filtering source code can have nasty side effects,
6711 so make an exception for our friends at sourceforge.net,
6712 and all paths with <quote>cvs</quote> in them. Note that
6713 <literal>-<link linkend="FILTER">filter</link></literal>
6714 disables <emphasis>all</emphasis> filters in one fell swoop!
6718 # Don't filter code!
6720 { -<link linkend="FILTER">filter</link> }
6725 .sourceforge.net</screen>
6728 The actual <filename>default.action</filename> is of course much more
6729 comprehensive, but we hope this example made clear how it works.
6734 <sect3 id="user-action"><title>user.action</title>
6737 So far we are painting with a broad brush by setting general policies,
6738 which would be a reasonable starting point for many people. Now,
6739 you might want to be more specific and have customized rules that
6740 are more suitable to your personal habits and preferences. These would
6741 be for narrowly defined situations like your ISP or your bank, and should
6742 be placed in <filename>user.action</filename>, which is parsed after all other
6743 actions files and hence has the last word, over-riding any previously
6744 defined actions. <filename>user.action</filename> is also a
6745 <emphasis>safe</emphasis> place for your personal settings, since
6746 <filename>default.action</filename> is actively maintained by the
6747 <application>Privoxy</application> developers and you'll probably want
6748 to install updated versions from time to time.
6752 So let's look at a few examples of things that one might typically do in
6753 <filename>user.action</filename>:
6757 <!-- brief sample user.action here -->
6760 # My user.action file. <fred@example.com></screen>
6763 As <link linkend="aliases">aliases</link> are local to the actions
6764 file that they are defined in, you can't use the ones from
6765 <filename>default.action</filename>, unless you repeat them here:
6769 # Aliases are local to the file they are defined in.
6770 # (Re-)define aliases for this file:
6774 # These aliases just save typing later, and the alias names should
6775 # be self explanatory.
6777 +crunch-all-cookies = +crunch-incoming-cookies +crunch-outgoing-cookies
6778 -crunch-all-cookies = -crunch-incoming-cookies -crunch-outgoing-cookies
6779 allow-all-cookies = -crunch-all-cookies -session-cookies-only
6780 allow-popups = -filter{all-popups}
6781 +block-as-image = +block{Blocked as image.} +handle-as-image
6782 -block-as-image = -block
6784 # These aliases define combinations of actions that are useful for
6785 # certain types of sites:
6787 fragile = -block -crunch-all-cookies -filter -fast-redirects -hide-referrer
6788 shop = -crunch-all-cookies allow-popups
6790 # Allow ads for selected useful free sites:
6792 allow-ads = -block -filter{banners-by-size} -filter{banners-by-link}
6794 # Alias for specific file types that are text, but might have conflicting
6795 # MIME types. We want the browser to force these to be text documents.
6796 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>
6799 Say you have accounts on some sites that you visit regularly, and
6800 you don't want to have to log in manually each time. So you'd like
6801 to allow persistent cookies for these sites. The
6802 <literal>allow-all-cookies</literal> alias defined above does exactly
6803 that, i.e. it disables crunching of cookies in any direction, and the
6804 processing of cookies to make them only temporary.
6808 { allow-all-cookies }
6812 .redhat.com</screen>
6815 Your bank is allergic to some filter, but you don't know which, so you disable them all:
6819 { -<link linkend="FILTER">filter</link> }
6820 .your-home-banking-site.com</screen>
6823 Some file types you may not want to filter for various reasons:
6827 # Technical documentation is likely to contain strings that might
6828 # erroneously get altered by the JavaScript-oriented filters:
6833 # And this stupid host sends streaming video with a wrong MIME type,
6834 # so that Privoxy thinks it is getting HTML and starts filtering:
6836 stupid-server.example.com/</screen>
6839 Example of a simple <link linkend="BLOCK">block</link> action. Say you've
6840 seen an ad on your favourite page on example.com that you want to get rid of.
6841 You have right-clicked the image, selected <quote>copy image location</quote>
6842 and pasted the URL below while removing the leading http://, into a
6843 <literal>{ +block{} }</literal> section. Note that <literal>{ +handle-as-image
6844 }</literal> need not be specified, since all URLs ending in
6845 <literal>.gif</literal> will be tagged as images by the general rules as set
6846 in default.action anyway:
6850 { +<link linkend="BLOCK">block</link>{Nasty ads.} }
6851 www.example.com/nasty-ads/sponsor\.gif
6852 another.example.net/more/junk/here/</screen>
6855 The URLs of dynamically generated banners, especially from large banner
6856 farms, often don't use the well-known image file name extensions, which
6857 makes it impossible for <application>Privoxy</application> to guess
6858 the file type just by looking at the URL.
6859 You can use the <literal>+block-as-image</literal> alias defined above for
6861 Note that objects which match this rule but then turn out NOT to be an
6862 image are typically rendered as a <quote>broken image</quote> icon by the
6863 browser. Use cautiously.
6871 ar.atwola.com/</screen>
6874 Now you noticed that the default configuration breaks Forbes Magazine,
6875 but you were too lazy to find out which action is the culprit, and you
6876 were again too lazy to give <link linkend="contact">feedback</link>, so
6877 you just used the <literal>fragile</literal> alias on the site, and
6878 -- <emphasis>whoa!</emphasis> -- it worked. The <literal>fragile</literal>
6879 aliases disables those actions that are most likely to break a site. Also,
6880 good for testing purposes to see if it is <application>Privoxy</application>
6881 that is causing the problem or not. We later find other regular sites
6882 that misbehave, and add those to our personalized list of troublemakers:
6889 .mybank.com</screen>
6892 You like the <quote>fun</quote> text replacements in <filename>default.filter</filename>,
6893 but it is disabled in the distributed actions file.
6894 So you'd like to turn it on in your private,
6895 update-safe config, once and for all:
6899 { +<link linkend="filter-fun">filter{fun}</link> }
6900 / # For ALL sites!</screen>
6903 Note that the above is not really a good idea: There are exceptions
6904 to the filters in <filename>default.action</filename> for things that
6905 really shouldn't be filtered, like code on CVS->Web interfaces. Since
6906 <filename>user.action</filename> has the last word, these exceptions
6907 won't be valid for the <quote>fun</quote> filtering specified here.
6911 You might also worry about how your favourite free websites are
6912 funded, and find that they rely on displaying banner advertisements
6913 to survive. So you might want to specifically allow banners for those
6914 sites that you feel provide value to you:
6924 Note that <literal>allow-ads</literal> has been aliased to
6925 <literal>-<link linkend="block">block</link></literal>,
6926 <literal>-<link linkend="filter-banners-by-size">filter{banners-by-size}</link></literal>, and
6927 <literal>-<link linkend="filter-banners-by-link">filter{banners-by-link}</link></literal> above.
6931 Invoke another alias here to force an over-ride of the MIME type <literal>
6932 application/x-sh</literal> which typically would open a download type
6933 dialog. In my case, I want to look at the shell script, and then I can save
6934 it should I choose to.
6942 <filename>user.action</filename> is generally the best place to define
6943 exceptions and additions to the default policies of
6944 <filename>default.action</filename>. Some actions are safe to have their
6945 default policies set here though. So let's set a default policy to have a
6946 <quote>blank</quote> image as opposed to the checkerboard pattern for
6947 <emphasis>ALL</emphasis> sites. <quote>/</quote> of course matches all URL
6952 { +<link linkend="set-image-blocker">set-image-blocker{blank}</link> }
6953 / # ALL sites</screen>
6958 <!-- ~ End section ~ -->
6962 <!-- ~ End section ~ -->
6964 <!-- ~~~~~~~~ New section Header ~~~~~~~~~ -->
6966 <sect1 id="filter-file">
6967 <title>Filter Files</title>
6970 On-the-fly text substitutions need
6971 to be defined in a <quote>filter file</quote>. Once defined, they
6972 can then be invoked as an <quote>action</quote>.
6976 &my-app; supports four different pcrs-based filter actions:
6977 <literal><link linkend="filter">filter</link></literal> to
6978 rewrite the content that is send to the client,
6979 <literal><link linkend="client-header-filter">client-header-filter</link></literal>
6980 to rewrite headers that are send by the client,
6981 <literal><link linkend="server-header-filter">server-header-filter</link></literal>
6982 to rewrite headers that are send by the server, and
6983 <literal><link linkend="client-body-filter">client-body-filter</link></literal>
6984 to rewrite client request body.
6988 &my-app; also supports two tagger actions:
6989 <literal><link linkend="client-header-tagger">client-header-tagger</link></literal>
6991 <literal><link linkend="server-header-tagger">server-header-tagger</link></literal>.
6992 Taggers and filters use the same syntax in the filter files, the difference
6993 is that taggers don't modify the text they are filtering, but use a rewritten
6994 version of the filtered text as tag. The tags can then be used to change the
6995 applying actions through sections with <link linkend="tag-pattern">tag-patterns</link>.
6999 Finally &my-app; supports the
7000 <literal><link linkend="external-filter">external-filter</link></literal> action
7001 to enable <literal><link linkend="external-filter-syntax">external filters</link></literal>
7002 written in proper programming languages.
7007 Multiple filter files can be defined through the <literal> <link
7008 linkend="filterfile">filterfile</link></literal> config directive. The filters
7009 as supplied by the developers are located in
7010 <filename>default.filter</filename>. It is recommended that any locally
7011 defined or modified filters go in a separately defined file such as
7012 <filename>user.filter</filename>.
7016 Common tasks for content filters are to eliminate common annoyances in
7017 HTML and JavaScript, such as pop-up windows,
7018 exit consoles, crippled windows without navigation tools, the
7019 infamous <BLINK> tag etc, to suppress images with certain
7020 width and height attributes (standard banner sizes or web-bugs),
7021 or just to have fun.
7025 Enabled content filters are applied to any content whose
7026 <quote>Content Type</quote> header is recognised as a sign
7027 of text-based content, with the exception of <literal>text/plain</literal>.
7028 Use the <link linkend="FORCE-TEXT-MODE">force-text-mode</link> action
7029 to also filter other content.
7033 Substitutions are made at the source level, so if you want to <quote>roll
7034 your own</quote> filters, you should first be familiar with HTML syntax,
7035 and, of course, regular expressions.
7039 Just like the <link linkend="actions-file">actions files</link>, the
7040 filter file is organized in sections, which are called <emphasis>filters</emphasis>
7041 here. Each filter consists of a heading line, that starts with one of the
7042 <emphasis>keywords</emphasis> <literal>FILTER:</literal>,
7043 <literal>CLIENT-HEADER-FILTER:</literal>, <literal>SERVER-HEADER-FILTER:</literal> or
7044 <literal>CLIENT-BODY-FILTER:</literal>
7045 followed by the filter's <emphasis>name</emphasis>, and a short (one line)
7046 <emphasis>description</emphasis> of what it does. Below that line
7047 come the <emphasis>jobs</emphasis>, i.e. lines that define the actual
7048 text substitutions. By convention, the name of a filter
7049 should describe what the filter <emphasis>eliminates</emphasis>. The
7050 comment is used in the <ulink url="http://config.privoxy.org/">web-based
7051 user interface</ulink>.
7055 Once a filter called <replaceable>name</replaceable> has been defined
7056 in the filter file, it can be invoked by using an action of the form
7057 +<literal><link linkend="filter">filter</link>{<replaceable>name</replaceable>}</literal>
7058 in any <link linkend="actions-file">actions file</link>.
7062 Filter definitions start with a header line that contains the filter
7063 type, the filter name and the filter description.
7064 A content filter header line for a filter called <quote>foo</quote> could look
7068 <screen>FILTER: foo Replace all "foo" with "bar"</screen>
7071 Below that line, and up to the next header line, come the jobs that
7072 define what text replacements the filter executes. They are specified
7073 in a syntax that imitates <ulink url="http://www.perl.org/">Perl</ulink>'s
7074 <literal>s///</literal> operator. If you are familiar with Perl, you
7075 will find this to be quite intuitive, and may want to look at the
7076 PCRS documentation for the subtle differences to Perl behaviour.
7080 Most notably, the non-standard option letter <literal>U</literal> is supported,
7081 which turns the default to ungreedy matching (add <literal>?</literal> to
7082 quantifiers to turn them greedy again).
7086 The non-standard option letter <literal>D</literal> (dynamic) allows
7087 to use the variables $host, $origin (the IP address the request came from),
7088 $path, $url and $listen-address (the address on which Privoxy accepted the
7089 client request. Example: 127.0.0.1:8118).
7090 They will be replaced with the value they refer to before the filter
7095 Note that '$' is a bad choice for a delimiter in a dynamic filter as you
7096 might end up with unintended variables if you use a variable name
7097 directly after the delimiter. Variables will be resolved without
7098 escaping anything, therefore you also have to be careful not to chose
7099 delimiters that appear in the replacement text. For example '<' should
7100 be save, while '?' will sooner or later cause conflicts with $url.
7104 The non-standard option letter <literal>T</literal> (trivial) prevents
7105 parsing for backreferences in the substitute. Use it if you want to include
7106 text like '$&' in your substitute without quoting.
7111 <ulink url="https://en.wikipedia.org/wiki/Regular_expressions"><quote>Regular
7112 Expressions</quote></ulink>, you might want to take a look at
7113 the <link linkend="regex">Appendix on regular expressions</link>, and
7114 see the <ulink url="http://perldoc.perl.org/perlre.html">Perl
7116 <ulink url="http://perldoc.perl.org/perlop.html">the
7117 <literal>s///</literal> operator's syntax</ulink> and <ulink
7118 url="http://perldoc.perl.org/perlre.html">Perl-style regular
7119 expressions</ulink> in general.
7120 The below examples might also help to get you started.
7124 <!-- ~~~~~~~~ New section Header ~~~~~~~~~ -->
7126 <sect2 id="filter-file-tut"><title>Filter File Tutorial</title>
7128 Now, let's complete our <quote>foo</quote> content filter. We have already defined
7129 the heading, but the jobs are still missing. Since all it does is to replace
7130 <quote>foo</quote> with <quote>bar</quote>, there is only one (trivial) job
7134 <screen>s/foo/bar/</screen>
7137 But wait! Didn't the comment say that <emphasis>all</emphasis> occurrences
7138 of <quote>foo</quote> should be replaced? Our current job will only take
7139 care of the first <quote>foo</quote> on each page. For global substitution,
7140 we'll need to add the <literal>g</literal> option:
7143 <screen>s/foo/bar/g</screen>
7146 Our complete filter now looks like this:
7149 <screen>FILTER: foo Replace all "foo" with "bar"
7150 s/foo/bar/g</screen>
7153 Let's look at some real filters for more interesting examples. Here you see
7154 a filter that protects against some common annoyances that arise from JavaScript
7155 abuse. Let's look at its jobs one after the other:
7160 FILTER: js-annoyances Get rid of particularly annoying JavaScript abuse
7162 # Get rid of JavaScript referrer tracking. Test page: http://www.randomoddness.com/untitled.htm
7164 s|(<script.*)document\.referrer(.*</script>)|$1"Not Your Business!"$2|Usg</screen>
7167 Following the header line and a comment, you see the job. Note that it uses
7168 <literal>|</literal> as the delimiter instead of <literal>/</literal>, because
7169 the pattern contains a forward slash, which would otherwise have to be escaped
7170 by a backslash (<literal>\</literal>).
7174 Now, let's examine the pattern: it starts with the text <literal><script.*</literal>
7175 enclosed in parentheses. Since the dot matches any character, and <literal>*</literal>
7176 means: <quote>Match an arbitrary number of the element left of myself</quote>, this
7177 matches <quote><script</quote>, followed by <emphasis>any</emphasis> text, i.e.
7178 it matches the whole page, from the start of the first <script> tag.
7182 That's more than we want, but the pattern continues: <literal>document\.referrer</literal>
7183 matches only the exact string <quote>document.referrer</quote>. The dot needed to
7184 be <emphasis>escaped</emphasis>, i.e. preceded by a backslash, to take away its
7185 special meaning as a joker, and make it just a regular dot. So far, the meaning is:
7186 Match from the start of the first <script> tag in a the page, up to, and including,
7187 the text <quote>document.referrer</quote>, if <emphasis>both</emphasis> are present
7188 in the page (and appear in that order).
7192 But there's still more pattern to go. The next element, again enclosed in parentheses,
7193 is <literal>.*</script></literal>. You already know what <literal>.*</literal>
7194 means, so the whole pattern translates to: Match from the start of the first <script>
7195 tag in a page to the end of the last <script> tag, provided that the text
7196 <quote>document.referrer</quote> appears somewhere in between.
7200 This is still not the whole story, since we have ignored the options and the parentheses:
7201 The portions of the page matched by sub-patterns that are enclosed in parentheses, will be
7202 remembered and be available through the variables <literal>$1, $2, ...</literal> in
7203 the substitute. The <literal>U</literal> option switches to ungreedy matching, which means
7204 that the first <literal>.*</literal> in the pattern will only <quote>eat up</quote> all
7205 text in between <quote><script</quote> and the <emphasis>first</emphasis> occurrence
7206 of <quote>document.referrer</quote>, and that the second <literal>.*</literal> will
7207 only span the text up to the <emphasis>first</emphasis> <quote></script></quote>
7208 tag. Furthermore, the <literal>s</literal> option says that the match may span
7209 multiple lines in the page, and the <literal>g</literal> option again means that the
7210 substitution is global.
7214 So, to summarize, the pattern means: Match all scripts that contain the text
7215 <quote>document.referrer</quote>. Remember the parts of the script from
7216 (and including) the start tag up to (and excluding) the string
7217 <quote>document.referrer</quote> as <literal>$1</literal>, and the part following
7218 that string, up to and including the closing tag, as <literal>$2</literal>.
7222 Now the pattern is deciphered, but wasn't this about substituting things? So
7223 lets look at the substitute: <literal>$1"Not Your Business!"$2</literal> is
7224 easy to read: The text remembered as <literal>$1</literal>, followed by
7225 <literal>"Not Your Business!"</literal> (<emphasis>including</emphasis>
7226 the quotation marks!), followed by the text remembered as <literal>$2</literal>.
7227 This produces an exact copy of the original string, with the middle part
7228 (the <quote>document.referrer</quote>) replaced by <literal>"Not Your
7229 Business!"</literal>.
7233 The whole job now reads: Replace <quote>document.referrer</quote> by
7234 <literal>"Not Your Business!"</literal> wherever it appears inside a
7235 <script> tag. Note that this job won't break JavaScript syntax,
7236 since both the original and the replacement are syntactically valid
7237 string objects. The script just won't have access to the referrer
7238 information anymore.
7242 We'll show you two other jobs from the JavaScript taming department, but
7243 this time only point out the constructs of special interest:
7247 # The status bar is for displaying link targets, not pointless blahblah
7249 s/window\.status\s*=\s*(['"]).*?\1/dUmMy=1/ig</screen>
7252 <literal>\s</literal> stands for whitespace characters (space, tab, newline,
7253 carriage return, form feed), so that <literal>\s*</literal> means: <quote>zero
7254 or more whitespace</quote>. The <literal>?</literal> in <literal>.*?</literal>
7255 makes this matching of arbitrary text ungreedy. (Note that the <literal>U</literal>
7256 option is not set). The <literal>['"]</literal> construct means: <quote>a single
7257 <emphasis>or</emphasis> a double quote</quote>. Finally, <literal>\1</literal> is
7258 a back-reference to the first parenthesis just like <literal>$1</literal> above,
7259 with the difference that in the <emphasis>pattern</emphasis>, a backslash indicates
7260 a back-reference, whereas in the <emphasis>substitute</emphasis>, it's the dollar.
7264 So what does this job do? It replaces assignments of single- or double-quoted
7265 strings to the <quote>window.status</quote> object with a dummy assignment
7266 (using a variable name that is hopefully odd enough not to conflict with
7267 real variables in scripts). Thus, it catches many cases where e.g. pointless
7268 descriptions are displayed in the status bar instead of the link target when
7269 you move your mouse over links.
7273 # Kill OnUnload popups. Yummy. Test: http://www.zdnet.com/zdsubs/yahoo/tree/yfs.html
7275 s/(<body [^>]*)onunload(.*>)/$1never$2/iU</screen>
7279 <ulink url="http://www.w3.org/TR/2000/REC-DOM-Level-2-Events-20001113/events.html#Events-eventgroupings-htmlevents">OnUnload
7280 event binding</ulink> in the HTML DOM was a <emphasis>CRIME</emphasis>.
7281 When I close a browser window, I want it to close and die. Basta.
7282 This job replaces the <quote>onunload</quote> attribute in
7283 <quote><body></quote> tags with the dummy word <literal>never</literal>.
7284 Note that the <literal>i</literal> option makes the pattern matching
7285 case-insensitive. Also note that ungreedy matching alone doesn't always guarantee
7286 a minimal match: In the first parenthesis, we had to use <literal>[^>]*</literal>
7287 instead of <literal>.*</literal> to prevent the match from exceeding the
7288 <body> tag if it doesn't contain <quote>OnUnload</quote>, but the page's
7293 The last example is from the fun department:
7297 FILTER: fun Fun text replacements
7299 # Spice the daily news:
7301 s/microsoft(?!\.com)/MicroSuck/ig</screen>
7304 Note the <literal>(?!\.com)</literal> part (a so-called negative lookahead)
7305 in the job's pattern, which means: Don't match, if the string
7306 <quote>.com</quote> appears directly following <quote>microsoft</quote>
7307 in the page. This prevents links to microsoft.com from being trashed, while
7308 still replacing the word everywhere else.
7312 # Buzzword Bingo (example for extended regex syntax)
7314 s* industry[ -]leading \
7316 | customer[ -]focused \
7317 | market[ -]driven \
7318 | award[ -]winning # Comments are OK, too! \
7319 | high[ -]performance \
7320 | solutions[ -]based \
7324 *<font color="red"><b>BINGO!</b></font> \
7328 The <literal>x</literal> option in this job turns on extended syntax, and allows for
7329 e.g. the liberal use of (non-interpreted!) whitespace for nicer formatting.
7337 <!-- ~~~~~~~~ New section Header ~~~~~~~~~ -->
7339 <sect2 id="predefined-filters"><title>The Pre-defined Filters</title>
7343 Note each filter is also listed in the +filter action section above. Please
7344 keep these listings in sync.
7349 The distribution <filename>default.filter</filename> file contains a selection of
7350 pre-defined filters for your convenience:
7355 <term><emphasis>js-annoyances</emphasis></term>
7358 The purpose of this filter is to get rid of particularly annoying JavaScript abuse.
7364 replaces JavaScript references to the browser's referrer information
7365 with the string "Not Your Business!". This compliments the <literal><link
7366 linkend="hide-referrer">hide-referrer</link></literal> action on the content level.
7371 removes the bindings to the DOM's
7372 <ulink url="http://www.w3.org/TR/2000/REC-DOM-Level-2-Events-20001113/events.html#Events-eventgroupings-htmlevents">unload
7373 event</ulink> which we feel has no right to exist and is responsible for most <quote>exit consoles</quote>, i.e.
7374 nasty windows that pop up when you close another one.
7379 removes code that causes new windows to be opened with undesired properties, such as being
7380 full-screen, non-resizeable, without location, status or menu bar etc.
7385 Use with caution. This is an aggressive filter, and can break sites that
7386 rely heavily on JavaScript.
7392 <term><emphasis>js-events</emphasis></term>
7395 This is a very radical measure. It removes virtually all JavaScript event bindings, which
7396 means that scripts can not react to user actions such as mouse movements or clicks, window
7397 resizing etc, anymore. Use with caution!
7400 We <emphasis>strongly discourage</emphasis> using this filter as a default since it breaks
7401 many legitimate scripts. It is meant for use only on extra-nasty sites (should you really
7408 <term><emphasis>html-annoyances</emphasis></term>
7411 This filter will undo many common instances of HTML based abuse.
7414 The <literal>BLINK</literal> and <literal>MARQUEE</literal> tags
7415 are neutralized (yeah baby!), and browser windows will be created as
7416 resizeable (as of course they should be!), and will have location,
7417 scroll and menu bars -- even if specified otherwise.
7423 <term><emphasis>content-cookies</emphasis></term>
7426 Most cookies are set in the HTTP dialog, where they can be intercepted
7428 <literal><link linkend="crunch-incoming-cookies">crunch-incoming-cookies</link></literal>
7429 and <literal><link linkend="crunch-outgoing-cookies">crunch-outgoing-cookies</link></literal>
7430 actions. But web sites increasingly make use of HTML meta tags and JavaScript
7431 to sneak cookies to the browser on the content level.
7434 This filter disables most HTML and JavaScript code that reads or sets
7435 cookies. It cannot detect all clever uses of these types of code, so it
7436 should not be relied on as an absolute fix. Use it wherever you would also
7437 use the cookie crunch actions.
7443 <term><emphasis>refresh-tags</emphasis></term>
7446 Disable any refresh tags if the interval is greater than nine seconds (so
7447 that redirections done via refresh tags are not destroyed). This is useful
7448 for dial-on-demand setups, or for those who find this HTML feature
7455 <term><emphasis>unsolicited-popups</emphasis></term>
7458 This filter attempts to prevent only <quote>unsolicited</quote> pop-up
7459 windows from opening, yet still allow pop-up windows that the user
7460 has explicitly chosen to open. It was added in version 3.0.1,
7461 as an improvement over earlier such filters.
7464 Technical note: The filter works by redefining the window.open JavaScript
7465 function to a dummy function, <literal>PrivoxyWindowOpen()</literal>,
7466 during the loading and rendering phase of each HTML page access, and
7467 restoring the function afterward.
7470 This is recommended only for browsers that cannot perform this function
7471 reliably themselves. And be aware that some sites require such windows
7472 in order to function normally. Use with caution.
7478 <term><emphasis>all-popups</emphasis></term>
7481 Attempt to prevent <emphasis>all</emphasis> pop-up windows from opening.
7482 Note this should be used with even more discretion than the above, since
7483 it is more likely to break some sites that require pop-ups for normal
7484 usage. Use with caution.
7490 <term><emphasis>img-reorder</emphasis></term>
7493 This is a helper filter that has no value if used alone. It makes the
7494 <literal>banners-by-size</literal> and <literal>banners-by-link</literal>
7495 (see below) filters more effective and should be enabled together with them.
7501 <term><emphasis>banners-by-size</emphasis></term>
7504 This filter removes image tags purely based on what size they are. Fortunately
7505 for us, many ads and banner images tend to conform to certain standardized
7506 sizes, which makes this filter quite effective for ad stripping purposes.
7509 Occasionally this filter will cause false positives on images that are not ads,
7510 but just happen to be of one of the standard banner sizes.
7513 Recommended only for those who require extreme ad blocking. The default
7514 block rules should catch 95+% of all ads <emphasis>without</emphasis> this filter enabled.
7520 <term><emphasis>banners-by-link</emphasis></term>
7523 This is an experimental filter that attempts to kill any banners if
7524 their URLs seem to point to known or suspected click trackers. It is currently
7525 not of much value and is not recommended for use by default.
7531 <term><emphasis>webbugs</emphasis></term>
7534 Webbugs are small, invisible images (technically 1X1 GIF images), that
7535 are used to track users across websites, and collect information on them.
7536 As an HTML page is loaded by the browser, an embedded image tag causes the
7537 browser to contact a third-party site, disclosing the tracking information
7538 through the requested URL and/or cookies for that third-party domain, without
7539 the user ever becoming aware of the interaction with the third-party site.
7540 HTML-ized spam also uses a similar technique to verify email addresses.
7543 This filter removes the HTML code that loads such <quote>webbugs</quote>.
7549 <term><emphasis>tiny-textforms</emphasis></term>
7552 A rather special-purpose filter that can be used to enlarge textareas (those
7553 multi-line text boxes in web forms) and turn off hard word wrap in them.
7554 It was written for the sourceforge.net tracker system where such boxes are
7555 a nuisance, but it can be handy on other sites, too.
7558 It is not recommended to use this filter as a default.
7564 <term><emphasis>jumping-windows</emphasis></term>
7567 Many consider windows that move, or resize themselves to be abusive. This filter
7568 neutralizes the related JavaScript code. Note that some sites might not display
7569 or behave as intended when using this filter. Use with caution.
7575 <term><emphasis>frameset-borders</emphasis></term>
7578 Some web designers seem to assume that everyone in the world will view their
7579 web sites using the same browser brand and version, screen resolution etc,
7580 because only that assumption could explain why they'd use static frame sizes,
7581 yet prevent their frames from being resized by the user, should they be too
7582 small to show their whole content.
7585 This filter removes the related HTML code. It should only be applied to sites
7592 <term><emphasis>demoronizer</emphasis></term>
7595 Many Microsoft products that generate HTML use non-standard extensions (read:
7596 violations) of the ISO 8859-1 aka Latin-1 character set. This can cause those
7597 HTML documents to display with errors on standard-compliant platforms.
7600 This filter translates the MS-only characters into Latin-1 equivalents.
7601 It is not necessary when using MS products, and will cause corruption of
7602 all documents that use 8-bit character sets other than Latin-1. It's mostly
7603 worthwhile for Europeans on non-MS platforms, if weird garbage characters
7604 sometimes appear on some pages, or user agents that don't correct for this on
7607 My version of Mozilla (ancient) shows little square boxes for quote
7608 characters, and apostrophes on moronized pages. So many pages have this, I
7609 can read them fine now. HB 08/27/06
7616 <term><emphasis>shockwave-flash</emphasis></term>
7619 A filter for shockwave haters. As the name suggests, this filter strips code
7620 out of web pages that is used to embed shockwave flash objects.
7628 <term><emphasis>quicktime-kioskmode</emphasis></term>
7631 Change HTML code that embeds Quicktime objects so that kioskmode, which
7632 prevents saving, is disabled.
7638 <term><emphasis>fun</emphasis></term>
7641 Text replacements for subversive browsing fun. Make fun of your favorite
7642 Monopolist or play buzzword bingo.
7648 <term><emphasis>crude-parental</emphasis></term>
7651 A demonstration-only filter that shows how <application>Privoxy</application>
7652 can be used to delete web content on a keyword basis.
7658 <term><emphasis>ie-exploits</emphasis></term>
7661 An experimental collection of text replacements to disable malicious HTML and JavaScript
7662 code that exploits known security holes in Internet Explorer.
7665 Presently, it only protects against Nimda and a cross-site scripting bug, and
7666 would need active maintenance to provide more substantial protection.
7672 <term><emphasis>site-specifics</emphasis></term>
7675 Some web sites have very specific problems, the cure for which doesn't apply
7676 anywhere else, or could even cause damage on other sites.
7679 This is a collection of such site-specific cures which should only be applied
7680 to the sites they were intended for, which is what the supplied
7681 <filename>default.action</filename> file does. Users shouldn't need to change
7682 anything regarding this filter.
7688 <term><emphasis>google</emphasis></term>
7691 A CSS based block for Google text ads. Also removes a width limitation
7692 and the toolbar advertisement.
7698 <term><emphasis>yahoo</emphasis></term>
7701 Another CSS based block, this time for Yahoo text ads. And removes
7702 a width limitation as well.
7708 <term><emphasis>msn</emphasis></term>
7711 Another CSS based block, this time for MSN text ads. And removes
7712 tracking URLs, as well as a width limitation.
7718 <term><emphasis>blogspot</emphasis></term>
7721 Cleans up some Blogspot blogs. Read the fine print before using this one!
7724 This filter also intentionally removes some navigation stuff and sets the
7725 page width to 100%. As a result, some rounded <quote>corners</quote> would
7726 appear to early or not at all and as fixing this would require a browser
7727 that understands background-size (CSS3), they are removed instead.
7733 <term><emphasis>xml-to-html</emphasis></term>
7736 Server-header filter to change the Content-Type from xml to html.
7742 <term><emphasis>html-to-xml</emphasis></term>
7745 Server-header filter to change the Content-Type from html to xml.
7751 <term><emphasis>no-ping</emphasis></term>
7754 Removes the non-standard <literal>ping</literal> attribute from
7755 anchor and area HTML tags.
7761 <term><emphasis>hide-tor-exit-notation</emphasis></term>
7764 Client-header filter to remove the <command>Tor</command> exit node notation
7765 found in Host and Referer headers.
7768 If &my-app; and <command>Tor</command> are chained and &my-app;
7769 is configured to use socks4a, one can use <quote>http://www.example.org.foobar.exit/</quote>
7770 to access the host <quote>www.example.org</quote> through the
7771 <command>Tor</command> exit node <quote>foobar</quote>.
7774 As the HTTP client isn't aware of this notation, it treats the
7775 whole string <quote>www.example.org.foobar.exit</quote> as host and uses it
7776 for the <quote>Host</quote> and <quote>Referer</quote> headers. From the
7777 server's point of view the resulting headers are invalid and can cause problems.
7780 An invalid <quote>Referer</quote> header can trigger <quote>hot-linking</quote>
7781 protections, an invalid <quote>Host</quote> header will make it impossible for
7782 the server to find the right vhost (several domains hosted on the same IP address).
7785 This client-header filter removes the <quote>foo.exit</quote> part in those headers
7786 to prevent the mentioned problems. Note that it only modifies
7787 the HTTP headers, it doesn't make it impossible for the server
7788 to detect your <command>Tor</command> exit node based on the IP address
7789 the request is coming from.
7796 <term><emphasis> </emphasis></term>
7809 <!-- ~~~~~~~~ New section Header ~~~~~~~~~ -->
7810 <sect2 id="external-filter-syntax"><title>External filter syntax</title>
7812 External filters are scripts or programs that can modify the content in
7813 case common <literal><link linkend="filter">filters</link></literal>
7814 aren't powerful enough.
7817 External filters can be written in any language the platform &my-app; runs
7821 They are controlled with the
7822 <literal><link linkend="external-filter">external-filter</link></literal> action
7823 and have to be defined in the <literal><link linkend="filterfile">filterfile</link></literal>
7827 The header looks like any other filter, but instead of pcrs jobs, external
7828 filters contain a single job which can be a program or a shell script (which
7829 may call other scripts or programs).
7832 External filters read the content from STDIN and write the rewritten
7834 The environment variables PRIVOXY_URL, PRIVOXY_PATH, PRIVOXY_HOST,
7835 PRIVOXY_ORIGIN, PRIVOXY_LISTEN_ADDRESS can be used to get some details
7836 about the client request.
7839 &my-app; will temporary store the content to filter in the
7840 <literal><link linkend="temporary-directory">temporary-directory</link></literal>.
7844 EXTERNAL-FILTER: cat Pointless example filter that doesn't actually modify the content
7847 # Incorrect reimplementation of the filter above in POSIX shell.
7849 # Note that it's a single job that spans multiple lines, the line
7850 # breaks are not passed to the shell, thus the semicolons are required.
7852 # If the script isn't trivial, it is recommended to put it into an external file.
7854 # In general, writing external filters entirely in POSIX shell is not
7855 # considered a good idea.
7856 EXTERNAL-FILTER: cat2 Pointless example filter that despite its name may actually modify the content
7862 EXTERNAL-FILTER: rotate-image Rotate an image by 180 degree. Test filter with limited value.
7863 /usr/local/bin/convert - -rotate 180 -
7865 EXTERNAL-FILTER: citation-needed Adds a "[citation needed]" tag to an image. The coordinates may need adjustment.
7866 /usr/local/bin/convert - -pointsize 16 -fill white -annotate +17+418 "[citation needed]" -
7871 Currently external filters are executed with &my-app;'s privileges!
7872 Only use external filters you understand and trust.
7876 External filters are experimental and the syntax may change in the future.
7882 <!-- ~ End section ~ -->
7886 <!-- ~~~~~ New section ~~~~~ -->
7888 <sect1 id="templates">
7889 <title>Privoxy's Template Files</title>
7891 All <application>Privoxy</application> built-in pages, i.e. error pages such as the
7892 <ulink url="http://show-the-404-error.page"><quote>404 - No Such Domain</quote>
7893 error page</ulink>, the <ulink
7894 url="http://ads.bannerserver.example.com/nasty-ads/sponsor.html"><quote>BLOCKED</quote>
7896 and all pages of its <ulink url="http://config.privoxy.org/">web-based
7897 user interface</ulink>, are generated from <emphasis>templates</emphasis>.
7898 (<application>Privoxy</application> must be running for the above links to work as
7903 These templates are stored in a subdirectory of the <link linkend="confdir">configuration
7904 directory</link> called <filename>templates</filename>. On Unixish platforms,
7906 <ulink url="file:///etc/privoxy/templates/"><filename>/etc/privoxy/templates/</filename></ulink>.
7910 The templates are basically normal HTML files, but with place-holders (called symbols
7911 or exports), which <application>Privoxy</application> fills at run time. It
7912 is possible to edit the templates with a normal text editor, should you want
7913 to customize them. (<emphasis>Not recommended for the casual
7914 user</emphasis>). Should you create your own custom templates, you should use
7915 the <filename>config</filename> setting <link linkend="templdir">templdir</link>
7916 to specify an alternate location, so your templates do not get overwritten
7920 Note that just like in configuration files, lines starting
7921 with <literal>#</literal> are ignored when the templates are filled in.
7925 The place-holders are of the form <literal>@name@</literal>, and you will
7926 find a list of available symbols, which vary from template to template,
7927 in the comments at the start of each file. Note that these comments are not
7928 always accurate, and that it's probably best to look at the existing HTML
7929 code to find out which symbols are supported and what they are filled in with.
7933 A special application of this substitution mechanism is to make whole
7934 blocks of HTML code disappear when a specific symbol is set. We use this
7935 for many purposes, one of them being to include the beta warning in all
7936 our user interface (CGI) pages when <application>Privoxy</application>
7937 is in an alpha or beta development stage:
7941 <!-- @if-unstable-start -->
7943 ... beta warning HTML code goes here ...
7945 <!-- if-unstable-end@ --></screen>
7948 If the "unstable" symbol is set, everything in between and including
7949 <literal>@if-unstable-start</literal> and <literal>if-unstable-end@</literal>
7950 will disappear, leaving nothing but an empty comment:
7953 <screen><!-- --></screen>
7956 There's also an if-then-else construct and an <literal>#include</literal>
7957 mechanism, but you'll sure find out if you are inclined to edit the
7962 All templates refer to a style located at
7963 <ulink url="http://config.privoxy.org/send-stylesheet"><literal>http://config.privoxy.org/send-stylesheet</literal></ulink>.
7964 This is, of course, locally served by <application>Privoxy</application>
7965 and the source for it can be found and edited in the
7966 <filename>cgi-style.css</filename> template.
7971 <!-- ~ End section ~ -->
7975 <!-- ~~~~~ New section ~~~~~ -->
7977 <sect1 id="contact"><title>Contacting the Developers, Bug Reporting and Feature
7980 <!-- Include contacting.sgml boilerplate: -->
7982 <!-- end boilerplate -->
7986 <!-- ~ End section ~ -->
7989 <!-- ~~~~~ New section ~~~~~ -->
7990 <sect1 id="copyright"><title>Privoxy Copyright, License and History</title>
7992 <!-- Include copyright.sgml: -->
7994 <!-- end copyright -->
7997 <application>Privoxy</application> is free software; you can
7998 redistribute and/or modify its source code under the terms
7999 of the <citetitle>GNU General Public License</citetitle>
8000 as published by the Free Software Foundation, either version 2
8001 of the license, or (at your option) any later version.
8005 The same is true for <application>Privoxy</application> binaries
8006 unless they are linked with a
8007 <ulink url="https://tls.mbed.org/">mbed TLS</ulink> version
8008 that is licensed under the Apache 2.0 license in which
8009 case you can redistribute and/or modify the <application>Privoxy</application>
8010 binaries under the terms of the <citetitle>GNU General Public License</citetitle>
8011 as published by the Free Software Foundation, either version 3
8012 of the license, or (at your option) any later version.
8016 Both licenses are included in the next section.
8019 <!-- ~~~~~ New section ~~~~~ -->
8020 <sect2 id="license"><title>License</title>
8022 <sect3 id="gplv2"><title>GNU General Public License version 2</title>
8023 <screen><![ RCDATA [ &GPLv2; ]]></screen>
8026 <sect3 id="gplv3"><title>GNU General Public License version 3</title>
8027 <screen><![ RCDATA [ &GPLv3; ]]></screen>
8031 <!-- ~ End section ~ -->
8034 <!-- ~~~~~ New section ~~~~~ -->
8036 <sect2 id="history"><title>History</title>
8037 <!-- Include history.sgml: -->
8039 <!-- end history -->
8042 <sect2 id="authors"><title>Authors</title>
8043 <!-- Include p-authors.sgml: -->
8045 <!-- end authors -->
8050 <!-- ~ End section ~ -->
8053 <!-- ~~~~~ New section ~~~~~ -->
8054 <sect1 id="seealso"><title>See Also</title>
8055 <!-- Include seealso.sgml: -->
8057 <!-- end seealso -->
8062 <!-- ~~~~~ New section ~~~~~ -->
8063 <sect1 id="appendix"><title>Appendix</title>
8066 <!-- ~~~~~ New section ~~~~~ -->
8068 <title>Regular Expressions</title>
8070 <application>Privoxy</application> uses Perl-style <quote>regular
8071 expressions</quote> in its <link linkend="actions-file">actions
8072 files</link> and <link linkend="filter-file">filter file</link>,
8073 through the <ulink url="http://www.pcre.org/">PCRE</ulink> and
8076 <ulink url="http://www.oesterhelt.org/pcrs/">PCRS</ulink> libraries.
8078 <application>PCRS</application> libraries.
8082 If you are reading this, you probably don't understand what <quote>regular
8083 expressions</quote> are, or what they can do. So this will be a very brief
8084 introduction only. A full explanation would require a <ulink
8085 url="http://www.oreilly.com/catalog/regex/">book</ulink> ;-)
8089 Regular expressions provide a language to describe patterns that can be
8090 run against strings of characters (letter, numbers, etc), to see if they
8091 match the string or not. The patterns are themselves (sometimes complex)
8092 strings of literal characters, combined with wild-cards, and other special
8093 characters, called meta-characters. The <quote>meta-characters</quote> have
8094 special meanings and are used to build complex patterns to be matched against.
8095 Perl Compatible Regular Expressions are an especially convenient
8096 <quote>dialect</quote> of the regular expression language.
8100 To make a simple analogy, we do something similar when we use wild-card
8101 characters when listing files with the <command>dir</command> command in DOS.
8102 <literal>*.*</literal> matches all filenames. The <quote>special</quote>
8103 character here is the asterisk which matches any and all characters. We can be
8104 more specific and use <literal>?</literal> to match just individual
8105 characters. So <quote>dir file?.text</quote> would match
8106 <quote>file1.txt</quote>, <quote>file2.txt</quote>, etc. We are pattern
8107 matching, using a similar technique to <quote>regular expressions</quote>!
8111 Regular expressions do essentially the same thing, but are much, much more
8112 powerful. There are many more <quote>special characters</quote> and ways of
8113 building complex patterns however. Let's look at a few of the common ones,
8114 and then some examples:
8119 <emphasis>.</emphasis> - Matches any single character, e.g. <quote>a</quote>,
8120 <quote>A</quote>, <quote>4</quote>, <quote>:</quote>, or <quote>@</quote>.
8126 <emphasis>?</emphasis> - The preceding character or expression is matched ZERO or ONE
8133 <emphasis>+</emphasis> - The preceding character or expression is matched ONE or MORE
8140 <emphasis>*</emphasis> - The preceding character or expression is matched ZERO or MORE
8147 <emphasis>\</emphasis> - The <quote>escape</quote> character denotes that
8148 the following character should be taken literally. This is used where one of the
8149 special characters (e.g. <quote>.</quote>) needs to be taken literally and
8150 not as a special meta-character. Example: <quote>example\.com</quote>, makes
8151 sure the period is recognized only as a period (and not expanded to its
8152 meta-character meaning of any single character).
8158 <emphasis>[ ]</emphasis> - Characters enclosed in brackets will be matched if
8159 any of the enclosed characters are encountered. For instance, <quote>[0-9]</quote>
8160 matches any numeric digit (zero through nine). As an example, we can combine
8161 this with <quote>+</quote> to match any digit one of more times: <quote>[0-9]+</quote>.
8167 <emphasis>( )</emphasis> - parentheses are used to group a sub-expression,
8168 or multiple sub-expressions.
8174 <emphasis>|</emphasis> - The <quote>bar</quote> character works like an
8175 <quote>or</quote> conditional statement. A match is successful if the
8176 sub-expression on either side of <quote>|</quote> matches. As an example:
8177 <quote>/(this|that) example/</quote> uses grouping and the bar character
8178 and would match either <quote>this example</quote> or <quote>that
8179 example</quote>, and nothing else.
8184 These are just some of the ones you are likely to use when matching URLs with
8185 <application>Privoxy</application>, and is a long way from a definitive
8186 list. This is enough to get us started with a few simple examples which may
8187 be more illuminating:
8191 <emphasis><literal>/.*/banners/.*</literal></emphasis> - A simple example
8192 that uses the common combination of <quote>.</quote> and <quote>*</quote> to
8193 denote any character, zero or more times. In other words, any string at all.
8194 So we start with a literal forward slash, then our regular expression pattern
8195 (<quote>.*</quote>) another literal forward slash, the string
8196 <quote>banners</quote>, another forward slash, and lastly another
8197 <quote>.*</quote>. We are building
8198 a directory path here. This will match any file with the path that has a
8199 directory named <quote>banners</quote> in it. The <quote>.*</quote> matches
8200 any characters, and this could conceivably be more forward slashes, so it
8201 might expand into a much longer looking path. For example, this could match:
8202 <quote>/eye/hate/spammers/banners/annoy_me_please.gif</quote>, or just
8203 <quote>/banners/annoying.html</quote>, or almost an infinite number of other
8204 possible combinations, just so it has <quote>banners</quote> in the path
8209 And now something a little more complex:
8213 <emphasis><literal>/.*/adv((er)?ts?|ertis(ing|ements?))?/</literal></emphasis> -
8214 We have several literal forward slashes again (<quote>/</quote>), so we are
8215 building another expression that is a file path statement. We have another
8216 <quote>.*</quote>, so we are matching against any conceivable sub-path, just so
8217 it matches our expression. The only true literal that <emphasis>must
8218 match</emphasis> our pattern is <application>adv</application>, together with
8219 the forward slashes. What comes after the <quote>adv</quote> string is the
8224 Remember the <quote>?</quote> means the preceding expression (either a
8225 literal character or anything grouped with <quote>(...)</quote> in this case)
8226 can exist or not, since this means either zero or one match. So
8227 <quote>((er)?ts?|ertis(ing|ements?))</quote> is optional, as are the
8228 individual sub-expressions: <quote>(er)</quote>,
8229 <quote>(ing|ements?)</quote>, and the <quote>s</quote>. The <quote>|</quote>
8230 means <quote>or</quote>. We have two of those. For instance,
8231 <quote>(ing|ements?)</quote>, can expand to match either <quote>ing</quote>
8232 <emphasis>OR</emphasis> <quote>ements?</quote>. What is being done here, is an
8233 attempt at matching as many variations of <quote>advertisement</quote>, and
8234 similar, as possible. So this would expand to match just <quote>adv</quote>,
8235 or <quote>advert</quote>, or <quote>adverts</quote>, or
8236 <quote>advertising</quote>, or <quote>advertisement</quote>, or
8237 <quote>advertisements</quote>. You get the idea. But it would not match
8238 <quote>advertizements</quote> (with a <quote>z</quote>). We could fix that by
8239 changing our regular expression to:
8240 <quote>/.*/adv((er)?ts?|erti(s|z)(ing|ements?))?/</quote>, which would then match
8245 <emphasis><literal>/.*/advert[0-9]+\.(gif|jpe?g)</literal></emphasis> - Again
8246 another path statement with forward slashes. Anything in the square brackets
8247 <quote>[ ]</quote> can be matched. This is using <quote>0-9</quote> as a
8248 shorthand expression to mean any digit one through nine. It is the same as
8249 saying <quote>0123456789</quote>. So any digit matches. The <quote>+</quote>
8250 means one or more of the preceding expression must be included. The preceding
8251 expression here is what is in the square brackets -- in this case, any digit
8252 one through nine. Then, at the end, we have a grouping: <quote>(gif|jpe?g)</quote>.
8253 This includes a <quote>|</quote>, so this needs to match the expression on
8254 either side of that bar character also. A simple <quote>gif</quote> on one side, and the other
8255 side will in turn match either <quote>jpeg</quote> or <quote>jpg</quote>,
8256 since the <quote>?</quote> means the letter <quote>e</quote> is optional and
8257 can be matched once or not at all. So we are building an expression here to
8258 match image GIF or JPEG type image file. It must include the literal
8259 string <quote>advert</quote>, then one or more digits, and a <quote>.</quote>
8260 (which is now a literal, and not a special character, since it is escaped
8261 with <quote>\</quote>), and lastly either <quote>gif</quote>, or
8262 <quote>jpeg</quote>, or <quote>jpg</quote>. Some possible matches would
8263 include: <quote>//advert1.jpg</quote>,
8264 <quote>/nasty/ads/advert1234.gif</quote>,
8265 <quote>/banners/from/hell/advert99.jpg</quote>. It would not match
8266 <quote>advert1.gif</quote> (no leading slash), or
8267 <quote>/adverts232.jpg</quote> (the expression does not include an
8268 <quote>s</quote>), or <quote>/advert1.jsp</quote> (<quote>jsp</quote> is not
8269 in the expression anywhere).
8273 We are barely scratching the surface of regular expressions here so that you
8274 can understand the default <application>Privoxy</application>
8275 configuration files, and maybe use this knowledge to customize your own
8276 installation. There is much, much more that can be done with regular
8277 expressions. Now that you know enough to get started, you can learn more on
8282 More reading on Perl Compatible Regular expressions:
8283 <ulink url="http://perldoc.perl.org/perlre.html">http://perldoc.perl.org/perlre.html</ulink>
8287 For information on regular expression based substitutions and their applications
8288 in filters, please see the <link linkend="filter-file">filter file tutorial</link>
8293 <!-- ~ End section ~ -->
8296 <!-- ~~~~~ New section ~~~~~ -->
8297 <sect2 id="internal-pages">
8298 <title>Privoxy's Internal Pages</title>
8301 Since <application>Privoxy</application> proxies each requested
8302 web page, it is easy for <application>Privoxy</application> to
8303 trap certain special URLs. In this way, we can talk directly to
8304 <application>Privoxy</application>, and see how it is
8305 configured, see how our rules are being applied, change these
8306 rules and other configuration options, and even turn
8307 <application>Privoxy's</application> filtering off, all with
8312 The URLs listed below are the special ones that allow direct access
8313 to <application>Privoxy</application>. Of course,
8314 <application>Privoxy</application> must be running to access these. If
8315 not, you will get a friendly error message. Internet access is not
8327 <ulink url="http://config.privoxy.org/">http://config.privoxy.org/</ulink>
8331 There is a shortcut: <ulink url="http://p.p/">http://p.p/</ulink> (But it
8332 doesn't provide a fall-back to a real page, in case the request is not
8333 sent through <application>Privoxy</application>)
8339 View and toggle client tags:
8343 <ulink url="http://config.privoxy.org/client-tags">http://config.privoxy.org/client-tags</ulink>
8350 Show information about the current configuration, including viewing and
8351 editing of actions files:
8355 <ulink url="http://config.privoxy.org/show-status">http://config.privoxy.org/show-status</ulink>
8362 Show the browser's request headers:
8366 <ulink url="http://config.privoxy.org/show-request">http://config.privoxy.org/show-request</ulink>
8373 Show which actions apply to a URL and why:
8377 <ulink url="http://config.privoxy.org/show-url-info">http://config.privoxy.org/show-url-info</ulink>
8384 Toggle Privoxy on or off. This feature can be turned off/on in the main
8385 <filename>config</filename> file. When toggled <quote>off</quote>, <quote>Privoxy</quote>
8386 continues to run, but only as a pass-through proxy, with no actions taking
8391 <ulink url="http://config.privoxy.org/toggle">http://config.privoxy.org/toggle</ulink>
8395 Short cuts. Turn off, then on:
8399 <ulink url="http://config.privoxy.org/toggle?set=disable">http://config.privoxy.org/toggle?set=disable</ulink>
8404 <ulink url="http://config.privoxy.org/toggle?set=enable">http://config.privoxy.org/toggle?set=enable</ulink>
8414 <!-- ~~~~~ New section ~~~~~ -->
8416 <title>Chain of Events</title>
8418 Let's take a quick look at how some of <application>Privoxy's</application>
8419 core features are triggered, and the ensuing sequence of events when a web
8420 page is requested by your browser:
8426 First, your web browser requests a web page. The browser knows to send
8427 the request to <application>Privoxy</application>, which will in turn,
8428 relay the request to the remote web server after passing the following
8434 <application>Privoxy</application> traps any request for its own internal CGI
8435 pages (e.g <ulink url="http://p.p/">http://p.p/</ulink>) and sends the CGI page back to the browser.
8440 Next, <application>Privoxy</application> checks to see if the URL
8442 linkend="BLOCK"><quote>+block</quote></link> patterns. If
8443 so, the URL is then blocked, and the remote web server will not be contacted.
8444 <link linkend="HANDLE-AS-IMAGE"><quote>+handle-as-image</quote></link>
8446 <link linkend="HANDLE-AS-EMPTY-DOCUMENT"><quote>+handle-as-empty-document</quote></link>
8447 are then checked, and if there is no match, an
8448 HTML <quote>BLOCKED</quote> page is sent back to the browser. Otherwise, if
8449 it does match, an image is returned for the former, and an empty text
8450 document for the latter. The type of image would depend on the setting of
8451 <link linkend="SET-IMAGE-BLOCKER"><quote>+set-image-blocker</quote></link>
8452 (blank, checkerboard pattern, or an HTTP redirect to an image elsewhere).
8457 Untrusted URLs are blocked. If URLs are being added to the
8458 <filename>trust</filename> file, then that is done.
8463 If the URL pattern matches the <link
8464 linkend="FAST-REDIRECTS"><quote>+fast-redirects</quote></link> action,
8465 it is then processed. Unwanted parts of the requested URL are stripped.
8470 Now the rest of the client browser's request headers are processed. If any
8471 of these match any of the relevant actions (e.g. <link
8472 linkend="HIDE-USER-AGENT"><quote>+hide-user-agent</quote></link>,
8473 etc.), headers are suppressed or forged as determined by these actions and
8479 Now the web server starts sending its response back (i.e. typically a web
8485 First, the server headers are read and processed to determine, among other
8486 things, the MIME type (document type) and encoding. The headers are then
8487 filtered as determined by the
8488 <link linkend="CRUNCH-INCOMING-COOKIES"><quote>+crunch-incoming-cookies</quote></link>,
8489 <link linkend="SESSION-COOKIES-ONLY"><quote>+session-cookies-only</quote></link>,
8490 and <link linkend="DOWNGRADE-HTTP-VERSION"><quote>+downgrade-http-version</quote></link>
8496 If any <link linkend="FILTER"><quote>+filter</quote></link> action
8498 linkend="DEANIMATE-GIFS"><quote>+deanimate-gifs</quote></link>
8499 action applies (and the document type fits the action), the rest of the page is
8500 read into memory (up to a configurable limit). Then the filter rules (from
8501 <filename>default.filter</filename> and any other filter files) are
8502 processed against the buffered content. Filters are applied in the order
8503 they are specified in one of the filter files. Animated GIFs, if present,
8504 are reduced to either the first or last frame, depending on the action
8505 setting.The entire page, which is now filtered, is then sent by
8506 <application>Privoxy</application> back to your browser.
8509 If neither a <link linkend="FILTER"><quote>+filter</quote></link> action
8511 linkend="DEANIMATE-GIFS"><quote>+deanimate-gifs</quote></link>
8512 matches, then <application>Privoxy</application> passes the raw data through
8513 to the client browser as it becomes available.
8518 As the browser receives the now (possibly filtered) page content, it
8519 reads and then requests any URLs that may be embedded within the page
8520 source, e.g. ad images, stylesheets, JavaScript, other HTML documents (e.g.
8521 frames), sounds, etc. For each of these objects, the browser issues a
8522 separate request (this is easily viewable in <application>Privoxy's</application>
8523 logs). And each such request is in turn processed just as above. Note that a
8524 complex web page will have many, many such embedded URLs. If these
8525 secondary requests are to a different server, then quite possibly a very
8526 differing set of actions is triggered.
8533 NOTE: This is somewhat of a simplistic overview of what happens with each URL
8534 request. For the sake of brevity and simplicity, we have focused on
8535 <application>Privoxy's</application> core features only.
8541 <!-- ~~~~~ New section ~~~~~ -->
8542 <sect2 id="actionsanat">
8543 <title>Troubleshooting: Anatomy of an Action</title>
8546 The way <application>Privoxy</application> applies
8547 <link linkend="ACTIONS">actions</link> and <link linkend="FILTER">filters</link>
8548 to any given URL can be complex, and not always so
8549 easy to understand what is happening. And sometimes we need to be able to
8550 <emphasis>see</emphasis> just what <application>Privoxy</application> is
8551 doing. Especially, if something <application>Privoxy</application> is doing
8552 is causing us a problem inadvertently. It can be a little daunting to look at
8553 the actions and filters files themselves, since they tend to be filled with
8554 <link linkend="regex">regular expressions</link> whose consequences are not
8559 One quick test to see if <application>Privoxy</application> is causing a problem
8560 or not, is to disable it temporarily. This should be the first troubleshooting
8561 step (be sure to flush caches afterward!). Looking at the
8562 logs is a good idea too. (Note that both the toggle feature and logging are
8563 enabled via <filename>config</filename> file settings, and may need to be
8564 turned <quote>on</quote>.)
8567 Another easy troubleshooting step to try is if you have done any
8568 customization of your installation, revert back to the installed
8569 defaults and see if that helps. There are times the developers get complaints
8570 about one thing or another, and the problem is more related to a customized
8571 configuration issue.
8575 <application>Privoxy</application> also provides the
8576 <ulink url="http://config.privoxy.org/show-url-info">http://config.privoxy.org/show-url-info</ulink>
8577 page that can show us very specifically how <application>actions</application>
8578 are being applied to any given URL. This is a big help for troubleshooting.
8582 First, enter one URL (or partial URL) at the prompt, and then
8583 <application>Privoxy</application> will tell us
8584 how the current configuration will handle it. This will not
8585 help with filtering effects (i.e. the <link
8586 linkend="FILTER"><quote>+filter</quote></link> action) from
8587 one of the filter files since this is handled very
8588 differently and not so easy to trap! It also will not tell you about any other
8589 URLs that may be embedded within the URL you are testing. For instance, images
8590 such as ads are expressed as URLs within the raw page source of HTML pages. So
8591 you will only get info for the actual URL that is pasted into the prompt area
8592 -- not any sub-URLs. If you want to know about embedded URLs like ads, you
8593 will have to dig those out of the HTML source. Use your browser's <quote>View
8594 Page Source</quote> option for this. Or right click on the ad, and grab the
8599 Let's try an example, <ulink url="http://google.com">google.com</ulink>,
8600 and look at it one section at a time in a sample configuration (your real
8601 configuration may vary):
8605 Matches for http://www.google.com:
8607 In file: default.action <guibutton>[ View ]</guibutton> <guibutton>[ Edit ]</guibutton>
8609 {+change-x-forwarded-for{block}
8610 +deanimate-gifs {last}
8611 +fast-redirects {check-decoded-url}
8612 +filter {refresh-tags}
8613 +filter {img-reorder}
8614 +filter {banners-by-size}
8616 +filter {jumping-windows}
8617 +filter {ie-exploits}
8618 +hide-from-header {block}
8619 +hide-referrer {forge}
8620 +session-cookies-only
8621 +set-image-blocker {pattern}
8624 { -session-cookies-only }
8630 In file: user.action <guibutton>[ View ]</guibutton> <guibutton>[ Edit ]</guibutton>
8631 (no matches in this file)
8635 This is telling us how we have defined our
8636 <link linkend="ACTIONS"><quote>actions</quote></link>, and
8637 which ones match for our test case, <quote>google.com</quote>.
8638 Displayed is all the actions that are available to us. Remember,
8639 the <literal>+</literal> sign denotes <quote>on</quote>. <literal>-</literal>
8640 denotes <quote>off</quote>. So some are <quote>on</quote> here, but many
8641 are <quote>off</quote>. Each example we try may provide a slightly different
8642 end result, depending on our configuration directives.
8646 is for our <filename>default.action</filename> file. The large, multi-line
8647 listing, is how the actions are set to match for all URLs, i.e. our default
8648 settings. If you look at your <quote>actions</quote> file, this would be the
8649 section just below the <quote>aliases</quote> section near the top. This
8650 will apply to all URLs as signified by the single forward slash at the end
8651 of the listing -- <quote> / </quote>.
8655 But we have defined additional actions that would be exceptions to these general
8656 rules, and then we list specific URLs (or patterns) that these exceptions
8657 would apply to. Last match wins. Just below this then are two explicit
8658 matches for <quote>.google.com</quote>. The first is negating our previous
8659 cookie setting, which was for <link
8660 linkend="SESSION-COOKIES-ONLY"><quote>+session-cookies-only</quote></link>
8661 (i.e. not persistent). So we will allow persistent cookies for google, at
8662 least that is how it is in this example. The second turns
8663 <emphasis>off</emphasis> any <link
8664 linkend="FAST-REDIRECTS"><quote>+fast-redirects</quote></link>
8665 action, allowing this to take place unmolested. Note that there is a leading
8666 dot here -- <quote>.google.com</quote>. This will match any hosts and
8667 sub-domains, in the google.com domain also, such as
8668 <quote>www.google.com</quote> or <quote>mail.google.com</quote>. But it would not
8669 match <quote>www.google.de</quote>! So, apparently, we have these two actions
8670 defined as exceptions to the general rules at the top somewhere in the lower
8671 part of our <filename>default.action</filename> file, and
8672 <quote>google.com</quote> is referenced somewhere in these latter sections.
8676 Then, for our <filename>user.action</filename> file, we again have no hits.
8677 So there is nothing google-specific that we might have added to our own, local
8678 configuration. If there was, those actions would over-rule any actions from
8679 previously processed files, such as <filename>default.action</filename>.
8680 <filename>user.action</filename> typically has the last word. This is the
8681 best place to put hard and fast exceptions,
8685 And finally we pull it all together in the bottom section and summarize how
8686 <application>Privoxy</application> is applying all its <quote>actions</quote>
8687 to <quote>google.com</quote>:
8695 +change-x-forwarded-for{block}
8696 -client-header-filter{hide-tor-exit-notation}
8697 -content-type-overwrite
8698 -crunch-client-header
8699 -crunch-if-none-match
8700 -crunch-incoming-cookies
8701 -crunch-outgoing-cookies
8702 -crunch-server-header
8703 +deanimate-gifs {last}
8704 -downgrade-http-version
8707 -filter {content-cookies}
8708 -filter {all-popups}
8709 -filter {banners-by-link}
8710 -filter {tiny-textforms}
8711 -filter {frameset-borders}
8712 -filter {demoronizer}
8713 -filter {shockwave-flash}
8714 -filter {quicktime-kioskmode}
8716 -filter {crude-parental}
8717 -filter {site-specifics}
8718 -filter {js-annoyances}
8719 -filter {html-annoyances}
8720 +filter {refresh-tags}
8721 -filter {unsolicited-popups}
8722 +filter {img-reorder}
8723 +filter {banners-by-size}
8725 +filter {jumping-windows}
8726 +filter {ie-exploits}
8733 -handle-as-empty-document
8735 -hide-accept-language
8736 -hide-content-disposition
8737 +hide-from-header {block}
8738 -hide-if-modified-since
8739 +hide-referrer {forge}
8742 -overwrite-last-modified
8743 -prevent-compression
8745 -server-header-filter{xml-to-html}
8746 -server-header-filter{html-to-xml}
8747 -session-cookies-only
8748 +set-image-blocker {pattern}
8752 Notice the only difference here to the previous listing, is to
8753 <quote>fast-redirects</quote> and <quote>session-cookies-only</quote>,
8754 which are activated specifically for this site in our configuration,
8755 and thus show in the <quote>Final Results</quote>.
8759 Now another example, <quote>ad.doubleclick.net</quote>:
8763 { +block{Domains starts with "ad"} }
8766 { +block{Domain contains "ad"} }
8769 { +block{Doubleclick banner server} +handle-as-image }
8770 .[a-vx-z]*.doubleclick.net
8774 We'll just show the interesting part here - the explicit matches. It is
8775 matched three different times. Two <quote>+block{}</quote> sections,
8776 and a <quote>+block{} +handle-as-image</quote>,
8777 which is the expanded form of one of our aliases that had been defined as:
8778 <quote>+block-as-image</quote>. (<link
8779 linkend="ALIASES"><quote>Aliases</quote></link> are defined in
8780 the first section of the actions file and typically used to combine more
8785 Any one of these would have done the trick and blocked this as an unwanted
8786 image. This is unnecessarily redundant since the last case effectively
8787 would also cover the first. No point in taking chances with these guys
8788 though ;-) Note that if you want an ad or obnoxious
8789 URL to be invisible, it should be defined as <quote>ad.doubleclick.net</quote>
8790 is done here -- as both a <link
8791 linkend="BLOCK"><quote>+block{}</quote></link>
8792 <emphasis>and</emphasis> an
8793 <link linkend="HANDLE-AS-IMAGE"><quote>+handle-as-image</quote></link>.
8794 The custom alias <quote><literal>+block-as-image</literal></quote> just
8795 simplifies the process and make it more readable.
8799 One last example. Let's try <quote>http://www.example.net/adsl/HOWTO/</quote>.
8800 This one is giving us problems. We are getting a blank page. Hmmm ...
8804 Matches for http://www.example.net/adsl/HOWTO/:
8806 In file: default.action <guibutton>[ View ]</guibutton> <guibutton>[ Edit ]</guibutton>
8810 +change-x-forwarded-for{block}
8811 -client-header-filter{hide-tor-exit-notation}
8812 -content-type-overwrite
8813 -crunch-client-header
8814 -crunch-if-none-match
8815 -crunch-incoming-cookies
8816 -crunch-outgoing-cookies
8817 -crunch-server-header
8819 -downgrade-http-version
8820 +fast-redirects {check-decoded-url}
8822 -filter {content-cookies}
8823 -filter {all-popups}
8824 -filter {banners-by-link}
8825 -filter {tiny-textforms}
8826 -filter {frameset-borders}
8827 -filter {demoronizer}
8828 -filter {shockwave-flash}
8829 -filter {quicktime-kioskmode}
8831 -filter {crude-parental}
8832 -filter {site-specifics}
8833 -filter {js-annoyances}
8834 -filter {html-annoyances}
8835 +filter {refresh-tags}
8836 -filter {unsolicited-popups}
8837 +filter {img-reorder}
8838 +filter {banners-by-size}
8840 +filter {jumping-windows}
8841 +filter {ie-exploits}
8848 -handle-as-empty-document
8850 -hide-accept-language
8851 -hide-content-disposition
8852 +hide-from-header{block}
8853 +hide-referer{forge}
8855 -overwrite-last-modified
8856 +prevent-compression
8858 -server-header-filter{xml-to-html}
8859 -server-header-filter{html-to-xml}
8860 +session-cookies-only
8861 +set-image-blocker{blank} }
8864 { +block{Path contains "ads".} +handle-as-image }
8869 Ooops, the <quote>/adsl/</quote> is matching <quote>/ads</quote> in our
8870 configuration! But we did not want this at all! Now we see why we get the
8871 blank page. It is actually triggering two different actions here, and
8872 the effects are aggregated so that the URL is blocked, and &my-app; is told
8873 to treat the block as if it were an image. But this is, of course, all wrong.
8874 We could now add a new action below this (or better in our own
8875 <filename>user.action</filename> file) that explicitly
8876 <emphasis>un</emphasis> blocks (
8877 <link linkend="BLOCK"><quote>{-block}</quote></link>) paths with
8878 <quote>adsl</quote> in them (remember, last match in the configuration
8879 wins). There are various ways to handle such exceptions. Example:
8888 Now the page displays ;-)
8889 Remember to flush your browser's caches when making these kinds of changes to
8890 your configuration to insure that you get a freshly delivered page! Or, try
8891 using <literal>Shift+Reload</literal>.
8895 But now what about a situation where we get no explicit matches like
8900 { +block{Path starts with "ads".} +handle-as-image }
8905 That actually was very helpful and pointed us quickly to where the problem
8906 was. If you don't get this kind of match, then it means one of the default
8907 rules in the first section of <filename>default.action</filename> is causing
8908 the problem. This would require some guesswork, and maybe a little trial and
8909 error to isolate the offending rule. One likely cause would be one of the
8910 <link linkend="FILTER"><quote>+filter</quote></link> actions.
8911 These tend to be harder to troubleshoot.
8912 Try adding the URL for the site to one of aliases that turn off
8913 <link linkend="FILTER"><quote>+filter</quote></link>:
8919 .worldpay.com # for quietpc.com
8926 <quote><literal>{ shop }</literal></quote> is an <quote>alias</quote> that expands to
8927 <quote><literal>{ -filter -session-cookies-only }</literal></quote>.
8928 Or you could do your own exception to negate filtering:
8933 # Disable ALL filter actions for sites in this section
8940 This would turn off all filtering for these sites. This is best
8941 put in <filename>user.action</filename>, for local site
8942 exceptions. Note that when a simple domain pattern is used by itself (without
8943 the subsequent path portion), all sub-pages within that domain are included
8944 automatically in the scope of the action.
8948 Images that are inexplicably being blocked, may well be hitting the
8949 <link linkend="FILTER-BANNERS-BY-SIZE"><quote>+filter{banners-by-size}</quote></link>
8951 that images of certain sizes are ad banners (works well
8952 <emphasis>most of the time</emphasis> since these tend to be standardized).
8956 <quote><literal>{ fragile }</literal></quote> is an alias that disables most
8957 actions that are the most likely to cause trouble. This can be used as a
8958 last resort for problem sites.
8963 # Handle with care: easy to break
8965 mybank.example.com</screen>
8969 <emphasis>Remember to flush caches!</emphasis> Note that the
8970 <literal>mail.google</literal> reference lacks the TLD portion (e.g.
8971 <quote>.com</quote>). This will effectively match any TLD with
8972 <literal>google</literal> in it, such as <literal>mail.google.de.</literal>,
8976 If this still does not work, you will have to go through the remaining
8977 actions one by one to find which one(s) is causing the problem.
8986 This program is free software; you can redistribute it
8987 and/or modify it under the terms of the GNU General
8988 Public License as published by the Free Software
8989 Foundation; either version 2 of the License, or (at
8990 your option) any later version.
8992 This program is distributed in the hope that it will
8993 be useful, but WITHOUT ANY WARRANTY; without even the
8994 implied warranty of MERCHANTABILITY or FITNESS FOR A
8995 PARTICULAR PURPOSE. See the GNU General Public
8996 License for more details.
8998 The GNU General Public License should be included with
8999 this file. If not, you can view it at
9000 http://www.gnu.org/copyleft/gpl.html
9001 or write to the Free Software Foundation, Inc.,
9002 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,