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6 <!entity seealso SYSTEM "seealso.sgml">
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10 <!entity copyright SYSTEM "copyright.sgml">
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16 <!entity changelog SYSTEM "changelog.sgml">
17 <!entity p-version "3.0.29">
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="http://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-os2"><title>OS/2</title>
234 First, make sure that no previous installations of
235 <application>Junkbuster</application> and / or
236 <application>Privoxy</application> are left on your
237 system. Check that no <application>Junkbuster</application>
238 or <application>Privoxy</application> objects are in
243 Then, just double-click the WarpIN self-installing archive, which will
244 guide you through the installation process. A shadow of the
245 <application>Privoxy</application> executable will be placed in your
246 startup folder so it will start automatically whenever OS/2 starts.
250 The directory you choose to install <application>Privoxy</application>
251 into will contain all of the configuration files.
255 <!-- ~~~~~ New section ~~~~~ -->
256 <sect3 id="installation-mac"><title>Mac OS X</title>
258 Installation instructions for the OS X platform depend upon whether
259 you downloaded a ready-built installation package (.pkg or .mpkg) or have
260 downloaded the source code.
263 <sect3 renderas="sect4" id="OS-X-install-from-package">
264 <title>Installation from ready-built package</title>
266 The downloaded file will either be a .pkg (for OS X 10.5 upwards) or a bzipped
267 .mpkg file (for OS X 10.4). The former can be double-clicked as is and the
268 installation will start; double-clicking the latter will unzip the .mpkg file
269 which can then be double-clicked to commence the installation.
272 The privoxy service will automatically start after a successful installation
273 (and thereafter every time your computer starts up) however you will need to
274 configure your web browser(s) to use it. To do so, configure them to use a
275 proxy for HTTP and HTTPS at the address 127.0.0.1:8118.
278 To prevent the privoxy service from automatically starting when your computer
279 starts up, remove or rename the file <literal>/Library/LaunchDaemons/org.ijbswa.privoxy.plist</literal>
280 (on OS X 10.5 and higher) or the folder named
281 <literal>/Library/StartupItems/Privoxy</literal> (on OS X 10.4 'Tiger').
284 To manually start or stop the privoxy service, use the scripts startPrivoxy.sh
285 and stopPrivoxy.sh supplied in /Applications/Privoxy. They must be run from an
286 administrator account, using sudo.
289 To uninstall, run /Applications/Privoxy/uninstall.command as sudo from an
290 administrator account.
293 <sect3 renderas="sect4" id="OS-X-install-from-source">
294 <title>Installation from source</title>
296 To build and install the Privoxy source code on OS X you will need to obtain
297 the macsetup module from the Privoxy Sourceforge CVS repository (refer to
298 Sourceforge help for details of how to set up a CVS client to have read-only
299 access to the repository). This module contains scripts that leverage the usual
300 open-source tools (available as part of Apple's free of charge Xcode
301 distribution or via the usual open-source software package managers for OS X
302 (MacPorts, Homebrew, Fink etc.) to build and then install the privoxy binary
303 and associated files. The macsetup module's README file contains complete
304 instructions for its use.
307 The privoxy service will automatically start after a successful installation
308 (and thereafter every time your computer starts up) however you will need to
309 configure your web browser(s) to use it. To do so, configure them to use a
310 proxy for HTTP and HTTPS at the address 127.0.0.1:8118.
313 To prevent the privoxy service from automatically starting when your computer
314 starts up, remove or rename the file <literal>/Library/LaunchDaemons/org.ijbswa.privoxy.plist</literal>
315 (on OS X 10.5 and higher) or the folder named
316 <literal>/Library/StartupItems/Privoxy</literal> (on OS X 10.4 'Tiger').
319 To manually start or stop the privoxy service, use the Privoxy Utility
320 for Mac OS X (also part of the macsetup module). This application can start
321 and stop the privoxy service and display its log and configuration files.
324 To uninstall, run the macsetup module's uninstall.sh as sudo from an
325 administrator account.
329 <!-- ~~~~~ New section ~~~~~ -->
330 <sect3 id="installation-freebsd"><title>FreeBSD</title>
333 Privoxy is part of FreeBSD's Ports Collection, you can build and install
334 it with <literal>cd /usr/ports/www/privoxy; make install clean</literal>.
340 <!-- ~~~~~ New section ~~~~~ -->
341 <sect2 id="installation-source"><title>Building from Source</title>
344 The most convenient way to obtain the <application>Privoxy</application> source
345 code is to download the source tarball from our
346 <ulink url="https://sourceforge.net/projects/ijbswa/files/Sources/">
347 project download page</ulink>,
348 or you can get the up-to-the-minute, possibly unstable, development version from
349 <ulink url="https://www.privoxy.org/">https://www.privoxy.org/</ulink>.
352 <!-- include buildsource.sgml boilerplate: -->
354 <!-- end boilerplate -->
357 <sect3 id="WINBUILD-CYGWIN"><title>Windows</title>
359 <sect4 id="WINBUILD-SETUP"><title>Setup</title>
361 Install the Cygwin utilities needed to build <application>Privoxy</application>.
362 If you have a 64 bit CPU (which most people do by now), get the
363 Cygwin setup-x86_64.exe program <ulink url="https://cygwin.com/setup-x86_64.exe">here</ulink>
364 (the .sig file is <ulink url="https://cygwin.com/setup-x86_64.exe.sig">here</ulink>).
367 Run the setup program and from View / Category select:
379 mingw64-i686-gcc-core
384 libxslt: GNOME XSLT library (runtime)
400 If you haven't already downloaded the Privoxy source code, get it now:
405 git clone https://www.privoxy.org/git/privoxy.git
409 Get the source code (.zip or .tar.gz) for tidy from
410 <ulink url="https://github.com/htacg/tidy-html5/releases">
411 https://github.com/htacg/tidy-html5/releases</ulink>,
412 unzip into <root-dir> and build the software:
416 cd tidy-html5-x.y.z/build/cmake
417 cmake ../.. -DCMAKE_BUILD_TYPE=Release -DBUILD_SHARED_LIB:BOOL=OFF -DCMAKE_INSTALL_PREFIX=/usr/local
422 If you want to be able to make a Windows release package, get the NSIS .zip file from
423 <!-- FIXME: which version(s) are known to work? -->
424 <ulink url="https://sourceforge.net/projects/nsis/files/NSIS%203/">
425 https://sourceforge.net/projects/nsis/files/NSIS%203/</ulink>
426 and extract the NSIS directory to <literal>privoxy/windows</literal>.
427 Then edit the windows/GNUmakefile to set the location of the NSIS executable - eg:
431 MAKENSIS = ./nsis/makensis.exe
436 <sect4 id="WINBUILD-BUILD"><title>Build</title>
439 To build just the Privoxy executable and not the whole installation package, do:
442 cd <root-dir>/privoxy
443 ./windows/MYconfigure && make
447 Privoxy uses the <ulink url="https://en.wikipedia.org/wiki/GNU_build_system">GNU Autotools</ulink>
448 for building software, so the process is:
451 $ autoheader # creates config.h.in
452 $ autoconf # uses config.h.in to create the configure shell script
453 $ ./configure [options] # creates GNUmakefile
454 $ make [options] # builds the program
458 The usual <literal>configure</literal> options for building a native Windows application under cygwin are
461 <literallayout class="Monospaced">
462 --host=i686-w64-mingw32
465 --enable-static-linking
467 --disable-dynamic-pcre
471 You can set the <literal>CFLAGS</literal> and <literal>LDFLAGS</literal> envars before
472 running <literal>configure</literal> to set compiler and linker flags. For example:
476 $ export CFLAGS="-O2" # set gcc optimization level
477 $ export LDFLAGS="-Wl,--nxcompat" # Enable DEP
478 $ ./configure --host=i686-w64-mingw32 --enable-mingw32 --enable-zlib \
479 > --enable-static-linking --disable-pthread --disable-dynamic-pcre
480 $ make # build Privoxy
484 See the <ulink url="../developer-manual/newrelease.html#NEWRELEASE-WINDOWS">Developer's Manual</ulink>
485 for building a Windows release package.
493 <!-- ~~~~~ New section ~~~~~ -->
494 <sect2 id="installation-keepupdated"><title>Keeping your Installation Up-to-Date</title>
497 If you wish to receive an email notification whenever we release updates of
498 <application>Privoxy</application> or the actions file, <ulink
499 url="https://lists.privoxy.org/mailman/listinfo/privoxy-announce">subscribe
500 to our announce mailing list</ulink>, privoxy-announce@lists.privoxy.org.
504 In order not to lose your personal changes and adjustments when updating
505 to the latest <literal>default.action</literal> file we <emphasis>strongly
506 recommend</emphasis> that you use <literal>user.action</literal> and
507 <literal>user.filter</literal> for your local
508 customizations of <application>Privoxy</application>. See the <link
509 linkend="actions-file">Chapter on actions files</link> for details.
517 <!-- ~ End section ~ -->
519 <!-- ~~~~~ New section ~~~~~ -->
520 <sect1 id="whatsnew">
521 <title>What's New in this Release</title>
525 <!-- ~~~~~ New section ~~~~~ -->
527 <sect2 id="upgradersnote">
528 <title>Note to Upgraders</title>
531 A quick list of things to be aware of before upgrading from earlier
532 versions of <application>Privoxy</application>:
539 The recommended way to upgrade &my-app; is to backup your old
540 configuration files, install the new ones, verify that &my-app;
541 is working correctly and finally merge back your changes using
542 <application>diff</application> and maybe <application>patch</application>.
545 There are a number of new features in each &my-app; release and
546 most of them have to be explicitly enabled in the configuration
547 files. Old configuration files obviously don't do that and due
548 to syntax changes using old configuration files with a new
549 &my-app; isn't always possible anyway.
554 Note that some installers remove earlier versions completely,
555 including configuration files, therefore you should really save
556 any important configuration files!
561 On the other hand, other installers don't overwrite existing configuration
562 files, thinking you will want to do that yourself.
567 In the default configuration only fatal errors are logged now.
568 You can change that in the <link linkend="DEBUG">debug section</link>
569 of the configuration file. You may also want to enable more verbose
570 logging until you verified that the new &my-app; version is working
577 Three other config file settings are now off by default:
578 <link linkend="enable-remote-toggle">enable-remote-toggle</link>,
579 <link linkend="enable-remote-http-toggle">enable-remote-http-toggle</link>,
580 and <link linkend="enable-edit-actions">enable-edit-actions</link>.
581 If you use or want these, you will need to explicitly enable them, and
582 be aware of the security issues involved.
589 What constitutes a <quote>default</quote> configuration has changed,
590 and you may want to review which actions are <quote>on</quote> by
591 default. This is primarily a matter of emphasis, but some features
592 you may have been used to, may now be <quote>off</quote> by default.
593 There are also a number of new actions and filters you may want to
594 consider, most of which are not fully incorporated into the default
595 settings as yet (see above).
602 The default actions setting is now <literal>Cautious</literal>. Previous
603 releases had a default setting of <literal>Medium</literal>. Experienced
604 users may want to adjust this, as it is fairly conservative by &my-app;
605 standards and past practices. See <ulink
606 url="http://config.privoxy.org/edit-actions-list?f=default">
607 http://config.privoxy.org/edit-actions-list?f=default</ulink>. New users
608 should try the default settings for a while before turning up the volume.
614 The default setting has filtering turned <emphasis>off</emphasis>, which
615 subsequently means that compression is <emphasis>on</emphasis>. Remember
616 that filtering does not work on compressed pages, so if you use, or want to
617 use, filtering, you will need to force compression off. Example:
620 { +<link linkend="filter">filter</link>{google} +<link linkend="prevent-compression">prevent-compression</link> }
623 Or if you use a number of filters, or filter many sites, you may just want
624 to turn off compression for all sites in
625 <filename>default.action</filename> (or
626 <filename>user.action</filename>).
633 Also, <link linkend="SESSION-COOKIES-ONLY">session-cookies-only</link> is
634 off by default now. If you've liked this feature in the past, you may want
635 to turn it back on in <filename>user.action</filename> now.
642 Some installers may not automatically start
643 <application>Privoxy</application> after installation.
653 <!-- ~~~~~ New section ~~~~~ -->
654 <sect1 id="quickstart"><title>Quickstart to Using Privoxy</title>
660 Install <application>Privoxy</application>. See the <link
661 linkend="installation">Installation Section</link> below for platform specific
668 Advanced users and those who want to offer <application>Privoxy</application>
669 service to more than just their local machine should check the <link
670 linkend="config">main config file</link>, especially the <link
671 linkend="access-control">security-relevant</link> options. These are
678 Start <application>Privoxy</application>, if the installation program has
679 not done this already (may vary according to platform). See the section
680 <link linkend="startup">Starting <application>Privoxy</application></link>.
686 Set your browser to use <application>Privoxy</application> as HTTP and
687 HTTPS (SSL) <ulink url="http://en.wikipedia.org/wiki/Proxy_server">proxy</ulink>
688 by setting the proxy configuration for address of
689 <literal>127.0.0.1</literal> and port <literal>8118</literal>.
690 <emphasis>DO NOT</emphasis> activate proxying for <literal>FTP</literal> or
691 any protocols besides HTTP and HTTPS (SSL) unless you intend to prevent your
692 browser from using these protocols.
698 Flush your browser's disk and memory caches, to remove any cached ad images.
699 If using <application>Privoxy</application> to manage
700 <ulink url="http://en.wikipedia.org/wiki/Browser_cookie">cookies</ulink>,
701 you should remove any currently stored cookies too.
707 A default installation should provide a reasonable starting point for
708 most. There will undoubtedly be occasions where you will want to adjust the
709 configuration, but that can be dealt with as the need arises. Little
710 to no initial configuration is required in most cases, you may want
712 <ulink url="config.html#ENABLE-EDIT-ACTIONS">web-based action editor</ulink> though.
713 Be sure to read the warnings first.
716 See the <link linkend="configuration">Configuration section</link> for more
717 configuration options, and how to customize your installation.
718 You might also want to look at the <link
719 linkend="quickstart-ad-blocking">next section</link> for a quick
720 introduction to how <application>Privoxy</application> blocks ads and
727 If you experience ads that slip through, innocent images that are
728 blocked, or otherwise feel the need to fine-tune
729 <application>Privoxy's</application> behavior, take a look at the <link
730 linkend="actions-file">actions files</link>. As a quick start, you might
731 find the <link linkend="act-examples">richly commented examples</link>
732 helpful. You can also view and edit the actions files through the <ulink
733 url="http://config.privoxy.org">web-based user interface</ulink>. The
734 Appendix <quote><link linkend="actionsanat">Troubleshooting: Anatomy of an
735 Action</link></quote> has hints on how to understand and debug actions that
736 <quote>misbehave</quote>.
742 Please see the section <link linkend="contact">Contacting the
743 Developers</link> on how to report bugs, problems with websites or to get
750 Now enjoy surfing with enhanced control, comfort and privacy!
757 <!-- ~~~~~ New section ~~~~~ -->
759 <sect2 id="quickstart-ad-blocking">
760 <title>Quickstart to Ad Blocking</title>
762 NOTE: This section is deliberately redundant for those that don't
763 want to read the whole thing (which is getting lengthy).
766 Ad blocking is but one of <application>Privoxy's</application>
767 array of features. Many of these features are for the technically minded advanced
768 user. But, ad and banner blocking is surely common ground for everybody.
771 This section will provide a quick summary of ad blocking so
772 you can get up to speed quickly without having to read the more extensive
773 information provided below, though this is highly recommended.
776 First a bit of a warning ... blocking ads is much like blocking SPAM: the
777 more aggressive you are about it, the more likely you are to block
778 things that were not intended. And the more likely that some things
779 may not work as intended. So there is a trade off here. If you want
780 extreme ad free browsing, be prepared to deal with more
781 <quote>problem</quote> sites, and to spend more time adjusting the
782 configuration to solve these unintended consequences. In short, there is
783 not an easy way to eliminate <emphasis>all</emphasis> ads. Either take
784 the easy way and settle for <emphasis>most</emphasis> ads blocked with the
785 default configuration, or jump in and tweak it for your personal surfing
786 habits and preferences.
789 Secondly, a brief explanation of <application>Privoxy's </application>
790 <quote>actions</quote>. <quote>Actions</quote> in this context, are
791 the directives we use to tell <application>Privoxy</application> to perform
792 some task relating to HTTP transactions (i.e. web browsing). We tell
793 <application>Privoxy</application> to take some <quote>action</quote>. Each
794 action has a unique name and function. While there are many potential
795 <application>actions</application> in <application>Privoxy's</application>
796 arsenal, only a few are used for ad blocking. <link
797 linkend="actions">Actions</link>, and <link linkend="actions-file">action
798 configuration files</link>, are explained in depth below.
801 Actions are specified in <application>Privoxy's</application> configuration,
802 followed by one or more URLs to which the action should apply. URLs
803 can actually be URL type <link linkend="af-patterns">patterns</link> that use
804 wildcards so they can apply potentially to a range of similar URLs. The
805 actions, together with the URL patterns are called a section.
808 When you connect to a website, the full URL will either match one or more
809 of the sections as defined in <application>Privoxy's</application> configuration,
810 or not. If so, then <application>Privoxy</application> will perform the
811 respective actions. If not, then nothing special happens. Furthermore, web
812 pages may contain embedded, secondary URLs that your web browser will
813 use to load additional components of the page, as it parses the
814 original page's HTML content. An ad image for instance, is just an URL
815 embedded in the page somewhere. The image itself may be on the same server,
816 or a server somewhere else on the Internet. Complex web pages will have many
817 such embedded URLs. &my-app; can deal with each URL individually, so, for
818 instance, the main page text is not touched, but images from such-and-such
823 The most important actions for basic ad blocking are: <literal><link
824 linkend="block">block</link></literal>, <literal><link
825 linkend="handle-as-image">handle-as-image</link></literal>,
827 linkend="handle-as-empty-document">handle-as-empty-document</link></literal>,and
828 <literal><link linkend="set-image-blocker">set-image-blocker</link></literal>:
835 <literal><link linkend="block">block</link></literal> - this is perhaps
836 the single most used action, and is particularly important for ad blocking.
837 This action stops any contact between your browser and any URL patterns
838 that match this action's configuration. It can be used for blocking ads,
839 but also anything that is determined to be unwanted. By itself, it simply
840 stops any communication with the remote server and sends
841 <application>Privoxy</application>'s own built-in BLOCKED page instead to
842 let you now what has happened (with some exceptions, see below).
848 <literal><link linkend="handle-as-image">handle-as-image</link></literal> -
849 tells <application>Privoxy</application> to treat this URL as an image.
850 <application>Privoxy</application>'s default configuration already does this
851 for all common image types (e.g. GIF), but there are many situations where this
852 is not so easy to determine. So we'll force it in these cases. This is particularly
853 important for ad blocking, since only if we know that it's an image of
854 some kind, can we replace it with an image of our choosing, instead of the
855 <application>Privoxy</application> BLOCKED page (which would only result in
856 a <quote>broken image</quote> icon). There are some limitations to this
857 though. For instance, you can't just brute-force an image substitution for
858 an entire HTML page in most situations.
864 <literal><link linkend="handle-as-empty-document">handle-as-empty-document</link></literal> -
865 sends an empty document instead of <application>Privoxy's</application>
866 normal BLOCKED HTML page. This is useful for file types that are neither
867 HTML nor images, such as blocking JavaScript files.
874 linkend="set-image-blocker">set-image-blocker</link></literal> - tells
875 <application>Privoxy</application> what to display in place of an ad image that
876 has hit a block rule. For this to come into play, the URL must match a
877 <literal><link linkend="block">block</link></literal> action somewhere in the
878 configuration, <emphasis>and</emphasis>, it must also match an
879 <literal><link linkend="handle-as-image">handle-as-image</link></literal> action.
882 The configuration options on what to display instead of the ad are:
886 <emphasis>pattern</emphasis> - a checkerboard pattern, so that an ad
887 replacement is obvious. This is the default.
892 <emphasis>blank</emphasis> - A very small empty GIF image is displayed.
893 This is the so-called <quote>invisible</quote> configuration option.
898 <emphasis>http://<URL></emphasis> - A redirect to any image anywhere
899 of the user's choosing (advanced usage).
907 Advanced users will eventually want to explore &my-app;
908 <literal><link linkend="filter">filters</link></literal> as well. Filters
909 are very different from <literal><link
910 linkend="block">blocks</link></literal>.
911 A <quote>block</quote> blocks a site, page, or unwanted contented. Filters
912 are a way of filtering or modifying what is actually on the page. An example
913 filter usage: a text replacement of <quote>no-no</quote> for
914 <quote>nasty-word</quote>. That is a very simple example. This process can be
915 used for ad blocking, but it is more in the realm of advanced usage and has
916 some pitfalls to be wary off.
920 The quickest way to adjust any of these settings is with your browser through
921 the special <application>Privoxy</application> editor at <ulink
922 url="http://config.privoxy.org/show-status">http://config.privoxy.org/show-status</ulink>
923 (shortcut: <ulink url="http://p.p/">http://p.p/show-status</ulink>). This
924 is an internal page, and does not require Internet access.
928 Note that as of <application>Privoxy</application> 3.0.7 beta the
929 action editor is disabled by default. Check the
930 <ulink url="config.html#ENABLE-EDIT-ACTIONS">enable-edit-actions
931 section in the configuration file</ulink> to learn why and in which
932 cases it's safe to enable again.
936 If you decided to enable the action editor, select the appropriate
937 <quote>actions</quote> file, and click
938 <quote><guibutton>Edit</guibutton></quote>. It is best to put personal or
939 local preferences in <filename>user.action</filename> since this is not
940 meant to be overwritten during upgrades, and will over-ride the settings in
941 other files. Here you can insert new <quote>actions</quote>, and URLs for ad
942 blocking or other purposes, and make other adjustments to the configuration.
943 <application>Privoxy</application> will detect these changes automatically.
947 A quick and simple step by step example:
954 Right click on the ad image to be blocked, then select
955 <quote><guimenuitem>Copy Link Location</guimenuitem></quote> from the
963 url="http://config.privoxy.org/show-status">http://config.privoxy.org/show-status</ulink>
968 Find <filename>user.action</filename> in the top section, and click
969 on <quote><guibutton>Edit</guibutton></quote>:
972 <!-- image of editor and actions files selections -->
973 <figure pgwide="0" float="0"><title>Actions Files in Use</title>
976 <imagedata fileref="files-in-use.jpg" format="jpg">
979 <phrase>[ Screenshot of Actions Files in Use ]</phrase>
987 You should have a section with only
988 <literal><link linkend="block">block</link></literal> listed under
989 <quote>Actions:</quote>.
990 If not, click a <quote><guibutton>Insert new section below</guibutton></quote>
991 button, and in the new section that just appeared, click the
992 <guibutton>Edit</guibutton> button right under the word <quote>Actions:</quote>.
993 This will bring up a list of all actions. Find
994 <literal><link linkend="block">block</link></literal> near the top, and click
995 in the <quote>Enabled</quote> column, then <quote><guibutton>Submit</guibutton></quote>
1001 Now, in the <literal><link linkend="block">block</link></literal> actions section,
1002 click the <quote><guibutton>Add</guibutton></quote> button, and paste the URL the
1003 browser got from <quote><guimenuitem>Copy Link Location</guimenuitem></quote>.
1004 Remove the <literal>http://</literal> at the beginning of the URL. Then, click
1005 <quote><guibutton>Submit</guibutton></quote> (or
1006 <quote><guibutton>OK</guibutton></quote> if in a pop-up window).
1011 Now go back to the original page, and press <keycap>SHIFT-Reload</keycap>
1012 (or flush all browser caches). The image should be gone now.
1019 This is a very crude and simple example. There might be good reasons to use a
1020 wildcard pattern match to include potentially similar images from the same
1021 site. For a more extensive explanation of <quote>patterns</quote>, and
1022 the entire actions concept, see <link linkend="actions-file">the Actions
1027 For advanced users who want to hand edit their config files, you might want
1028 to now go to the <link linkend="act-examples">Actions Files Tutorial</link>.
1029 The ideas explained therein also apply to the web-based editor.
1032 There are also various
1033 <link linkend="filter">filters</link> that can be used for ad blocking
1034 (filters are a special subset of actions). These
1035 fall into the <quote>advanced</quote> usage category, and are explained in
1036 depth in later sections.
1043 <!-- ~ End section ~ -->
1046 <!-- ~~~~~ New section ~~~~~ -->
1047 <sect1 id="startup">
1048 <title>Starting Privoxy</title>
1050 Before launching <application>Privoxy</application> for the first time, you
1051 will want to configure your browser(s) to use
1052 <application>Privoxy</application> as a HTTP and HTTPS (SSL)
1053 <ulink url="http://en.wikipedia.org/wiki/Proxy_server">proxy</ulink>. The default is
1054 127.0.0.1 (or localhost) for the proxy address, and port 8118 (earlier versions
1055 used port 8000). This is the one configuration step <emphasis>that must be done
1059 Please note that <application>Privoxy</application> can only proxy HTTP and
1060 HTTPS traffic. It will not work with FTP or other protocols.
1063 <!-- image of Mozilla Proxy configuration -->
1064 <figure pgwide="0" float="0"><title>Proxy Configuration Showing
1065 Mozilla/Netscape HTTP and HTTPS (SSL) Settings</title>
1068 <imagedata fileref="proxy_setup.jpg" format="jpg">
1071 <phrase>[ Screenshot of Mozilla Proxy Configuration ]</phrase>
1078 With <application>Firefox</application>, this is typically set under:
1082 <guibutton>Tools</guibutton> -> <guibutton>Options</guibutton> -> <guibutton>Advanced</guibutton> -> <guibutton>Network</guibutton> -><guibutton>Connection</guibutton> -> <guibutton>Settings</guibutton>
1086 Or optionally on some platforms:
1090 <guibutton>Edit</guibutton> -> <guibutton>Preferences</guibutton> -> <guibutton>General</guibutton> -> <guibutton>Connection Settings</guibutton> -> <guibutton>Manual Proxy Configuration</guibutton>
1095 With <application>Netscape</application> (and
1096 <application>Mozilla</application>), this can be set under:
1101 <!-- Mix ascii and gui art, something for everybody -->
1102 <!-- spacing on this is tricky -->
1103 <guibutton>Edit</guibutton> -> <guibutton>Preferences</guibutton> -> <guibutton>Advanced</guibutton> -> <guibutton>Proxies</guibutton> -> <guibutton>HTTP Proxy</guibutton>
1107 For <application>Internet Explorer v.5-7</application>:
1111 <guibutton>Tools</guibutton> -> <guibutton>Internet Options</guibutton> -> <guibutton>Connections</guibutton> -> <guibutton>LAN Settings</guibutton>
1115 Then, check <quote>Use Proxy</quote> and fill in the appropriate info
1116 (Address: 127.0.0.1, Port: 8118). Include HTTPS (SSL), if you want HTTPS
1117 proxy support too (sometimes labeled <quote>Secure</quote>). Make sure any
1118 checkboxes like <quote>Use the same proxy server for all protocols</quote> is
1119 <emphasis>UNCHECKED</emphasis>. You want only HTTP and HTTPS (SSL)!
1122 <!-- image of IE Proxy configuration -->
1123 <figure pgwide="0" float="0"><title>Proxy Configuration Showing
1124 Internet Explorer HTTP and HTTPS (Secure) Settings</title>
1127 <imagedata fileref="proxy2.jpg" format="jpg">
1130 <phrase>[ Screenshot of IE Proxy Configuration ]</phrase>
1137 After doing this, flush your browser's disk and memory caches to force a
1138 re-reading of all pages and to get rid of any ads that may be cached. Remove
1139 any <ulink url="http://en.wikipedia.org/wiki/Browser_cookie">cookies</ulink>,
1140 if you want <application>Privoxy</application> to manage that. You are now
1141 ready to start enjoying the benefits of using
1142 <application>Privoxy</application>!
1146 <application>Privoxy</application> itself is typically started by specifying the
1147 main configuration file to be used on the command line. If no configuration
1148 file is specified on the command line, <application>Privoxy</application>
1149 will look for a file named <filename>config</filename> in the current
1150 directory. Except on Win32 where it will try <filename>config.txt</filename>.
1153 <sect2 id="start-debian">
1154 <title>Debian</title>
1156 We use a script. Note that Debian typically starts &my-app; upon booting per
1157 default. It will use the file
1158 <filename>/etc/privoxy/config</filename> as its main configuration
1162 # /etc/init.d/privoxy start
1166 <sect2 id="start-freebsd">
1167 <title>FreeBSD and ElectroBSD</title>
1169 To start <application>Privoxy</application> upon booting, add
1170 "privoxy_enable='YES'" to <filename>/etc/rc.conf</filename>.
1171 <application>Privoxy</application> will use
1172 <filename>/usr/local/etc/privoxy/config</filename> as its main
1176 If you installed <application>Privoxy</application> into a jail, the
1177 paths above are relative to the jail root.
1180 To start <application>Privoxy</application> manually, run:
1183 # service privoxy onestart
1187 <sect2 id="start-windows">
1188 <title>Windows</title>
1190 Click on the &my-app; Icon to start <application>Privoxy</application>. If no configuration file is
1191 specified on the command line, <application>Privoxy</application> will look
1192 for a file named <filename>config.txt</filename>. Note that Windows will
1193 automatically start &my-app; when the system starts if you chose that option
1197 <application>Privoxy</application> can run with full Windows service functionality.
1198 On Windows only, the &my-app; program has two new command line arguments
1199 to install and uninstall &my-app; as a service. See the
1200 <link linkend="installation-pack-win">Windows Installation
1201 instructions</link> for details.
1205 <sect2 id="start-unices">
1206 <title>Generic instructions for Unix derivates (Solaris, NetBSD, HP-UX etc.)</title>
1208 Example Unix startup command:
1211 # /usr/sbin/privoxy --user privoxy /etc/privoxy/config
1214 Note that if you installed <application>Privoxy</application> through
1215 a package manager, the package will probably contain a platform-specific
1216 script or configuration file to start <application>Privoxy</application>
1221 <sect2 id="start-os2">
1224 During installation, <application>Privoxy</application> is configured to
1225 start automatically when the system restarts. You can start it manually by
1226 double-clicking on the <application>Privoxy</application> icon in the
1227 <application>Privoxy</application> folder.
1231 <sect2 id="start-macosx">
1232 <title>Mac OS X</title>
1234 The privoxy service will automatically start after a successful installation
1235 (and thereafter every time your computer starts up) however you will need to
1236 configure your web browser(s) to use it. To do so, configure them to use a
1237 proxy for HTTP and HTTPS at the address 127.0.0.1:8118.
1240 To prevent the privoxy service from automatically starting when your computer
1241 starts up, remove or rename the file <literal>/Library/LaunchDaemons/org.ijbswa.privoxy.plist</literal>
1242 (on OS X 10.5 and higher) or the folder named
1243 <literal>/Library/StartupItems/Privoxy</literal> (on OS X 10.4 'Tiger').
1246 To manually start or stop the privoxy service, use the scripts startPrivoxy.sh
1247 and stopPrivoxy.sh supplied in /Applications/Privoxy. They must be run from an
1248 administrator account, using sudo.
1256 See the section <link linkend="cmdoptions">Command line options</link> for
1260 must find a better place for this paragraph
1263 The included default configuration files should give a reasonable starting
1264 point. Most of the per site configuration is done in the
1265 <ulink url="actions-file.html"><quote>actions</quote></ulink> files. These are
1266 where various cookie actions are defined, ad and banner blocking, and other
1267 aspects of <application>Privoxy</application> configuration. There are several
1268 such files included, with varying levels of aggressiveness.
1272 You will probably want to keep an eye out for sites for which you may prefer
1273 persistent cookies, and add these to your actions configuration as needed. By
1274 default, most of these will be accepted only during the current browser
1275 session (aka <quote>session cookies</quote>), unless you add them to the
1276 configuration. If you want the browser to handle this instead, you will need
1277 to edit <filename>user.action</filename> (or through the web based interface)
1278 and disable this feature. If you use more than one browser, it would make
1279 more sense to let <application>Privoxy</application> handle this. In which
1280 case, the browser(s) should be set to accept all cookies.
1284 Another feature where you will probably want to define exceptions for trusted
1285 sites is the popup-killing (through <ulink
1286 url="actions-file.html#FILTER-POPUPS"><quote>+filter{popups}</quote></ulink>),
1287 because your favorite shopping, banking, or leisure site may need
1288 popups (explained below).
1292 <application>Privoxy</application> does not support all of the optional HTTP/1.1
1293 features yet. In the unlikely event that you experience inexplicable problems
1294 with browsers that use HTTP/1.1 per default
1295 (like <application>Mozilla</application> or recent versions of I.E.), you might
1296 try to force HTTP/1.0 compatibility. For Mozilla, look under <literal>Edit ->
1297 Preferences -> Debug -> Networking</literal>.
1298 Alternatively, set the <quote>+downgrade-http-version</quote> config option in
1299 <filename>default.action</filename> which will downgrade your browser's HTTP
1300 requests from HTTP/1.1 to HTTP/1.0 before processing them.
1304 After running <application>Privoxy</application> for a while, you can
1305 start to fine tune the configuration to suit your personal, or site,
1306 preferences and requirements. There are many, many aspects that can
1307 be customized. <quote>Actions</quote>
1308 can be adjusted by pointing your browser to
1309 <ulink url="http://config.privoxy.org/">http://config.privoxy.org/</ulink>
1310 (shortcut: <ulink url="http://p.p/">http://p.p/</ulink>),
1311 and then follow the link to <quote>View & Change the Current Configuration</quote>.
1312 (This is an internal page and does not require Internet access.)
1316 In fact, various aspects of <application>Privoxy</application>
1317 configuration can be viewed from this page, including
1318 current configuration parameters, source code version numbers,
1319 the browser's request headers, and <quote>actions</quote> that apply
1320 to a given URL. In addition to the actions file
1321 editor mentioned above, <application>Privoxy</application> can also
1322 be turned <quote>on</quote> and <quote>off</quote> (toggled) from this page.
1326 If you encounter problems, try loading the page without
1327 <application>Privoxy</application>. If that helps, enter the URL where
1328 you have the problems into <ulink url="http://p.p/show-url-info">the browser
1329 based rule tracing utility</ulink>. See which rules apply and why, and
1330 then try turning them off for that site one after the other, until the problem
1331 is gone. When you have found the culprit, you might want to turn the rest on
1336 If the above paragraph sounds gibberish to you, you might want to <link
1337 linkend="actions-file">read more about the actions concept</link>
1338 or even dive deep into the <link linkend="actionsanat">Appendix
1343 If you can't get rid of the problem at all, think you've found a bug in
1344 Privoxy, want to propose a new feature or smarter rules, please see the
1345 section <link linkend="contact"><quote>Contacting the
1346 Developers</quote></link> below.
1351 <!-- ~~~~~ New section ~~~~~ -->
1352 <sect2 id="cmdoptions">
1353 <title>Command Line Options</title>
1355 <application>Privoxy</application> may be invoked with the following
1356 command-line options:
1363 <emphasis>--config-test</emphasis>
1366 Exit after loading the configuration files before binding to
1367 the listen address. The exit code signals whether or not the
1368 configuration files have been successfully loaded.
1371 If the exit code is 1, at least one of the configuration files
1372 is invalid, if it is 0, all the configuration files have been
1373 successfully loaded (but may still contain errors that can
1374 currently only be detected at run time).
1377 This option doesn't affect the log setting, combination with
1378 <emphasis>--no-daemon</emphasis> is recommended if a configured
1379 log file shouldn't be used.
1384 <emphasis>--version</emphasis>
1387 Print version info and exit. Unix only.
1392 <emphasis>--help</emphasis>
1395 Print short usage info and exit. Unix only.
1400 <emphasis>--no-daemon</emphasis>
1403 Don't become a daemon, i.e. don't fork and become process group
1404 leader, and don't detach from controlling tty. Unix only.
1409 <emphasis>--pidfile FILE</emphasis>
1412 On startup, write the process ID to <emphasis>FILE</emphasis>. Delete the
1413 <emphasis>FILE</emphasis> on exit. Failure to create or delete the
1414 <emphasis>FILE</emphasis> is non-fatal. If no <emphasis>FILE</emphasis>
1415 option is given, no PID file will be used. Unix only.
1420 <emphasis>--user USER[.GROUP]</emphasis>
1423 After (optionally) writing the PID file, assume the user ID of
1424 <emphasis>USER</emphasis>, and if included the GID of GROUP. Exit if the
1425 privileges are not sufficient to do so. Unix only.
1430 <emphasis>--chroot</emphasis>
1433 Before changing to the user ID given in the <emphasis>--user</emphasis> option,
1434 chroot to that user's home directory, i.e. make the kernel pretend to the &my-app;
1435 process that the directory tree starts there. If set up carefully, this can limit
1436 the impact of possible vulnerabilities in &my-app; to the files contained in that hierarchy.
1442 <emphasis>--pre-chroot-nslookup hostname</emphasis>
1445 Specifies a hostname (for example www.privoxy.org) to look up before doing a chroot.
1446 On some systems, initializing the resolver library involves reading config files from
1447 /etc and/or loading additional shared libraries from /lib.
1448 On these systems, doing a hostname lookup before the chroot reduces
1449 the number of files that must be copied into the chroot tree.
1452 For fastest startup speed, a good value is a hostname that is not in /etc/hosts but that
1453 your local name server (listed in /etc/resolv.conf) can resolve without recursion
1454 (that is, without having to ask any other name servers). The hostname need not exist,
1455 but if it doesn't, an error message (which can be ignored) will be output.
1461 <emphasis>configfile</emphasis>
1464 If no <emphasis>configfile</emphasis> is included on the command line,
1465 <application>Privoxy</application> will look for a file named
1466 <quote>config</quote> in the current directory (except on Win32
1467 where it will look for <quote>config.txt</quote> instead). Specify
1468 full path to avoid confusion. If no config file is found,
1469 <application>Privoxy</application> will fail to start.
1476 On <application>MS Windows</application> only there are two additional
1477 command-line options to allow <application>Privoxy</application> to install and
1478 run as a <emphasis>service</emphasis>. See the
1479 <link linkend="installation-pack-win">Window Installation section</link>
1487 <!-- ~ End section ~ -->
1490 <!-- ~~~~~ New section ~~~~~ -->
1491 <sect1 id="configuration"><title>Privoxy Configuration</title>
1493 All <application>Privoxy</application> configuration is stored
1494 in text files. These files can be edited with a text editor.
1495 Many important aspects of <application>Privoxy</application> can
1496 also be controlled easily with a web browser.
1500 <!-- ~~~~~ New section ~~~~~ -->
1502 <sect2 id="control-with-webbrowser">
1503 <title>Controlling Privoxy with Your Web Browser</title>
1505 <application>Privoxy</application>'s user interface can be reached through the special
1506 URL <ulink url="http://config.privoxy.org/">http://config.privoxy.org/</ulink>
1507 (shortcut: <ulink url="http://p.p/">http://p.p/</ulink>),
1508 which is a built-in page and works without Internet access.
1509 You will see the following section:
1512 <!-- Needs to be put in a table and colorized -->
1513 <screen><!-- want the background color that goes with screen -->
1515 <bridgehead renderas="sect2"> Privoxy Menu</bridgehead>
1518 ▪ <ulink url="http://config.privoxy.org/show-status">View & change the current configuration</ulink>
1521 ▪ <ulink url="http://config.privoxy.org/client-tags">View or toggle the tags that can be set based on the clients address</ulink>
1524 ▪ <ulink url="http://config.privoxy.org/show-request">View the request headers.</ulink>
1527 ▪ <ulink url="http://config.privoxy.org/show-url-info">Look up which actions apply to a URL and why</ulink>
1530 ▪ <ulink url="http://config.privoxy.org/toggle">Toggle Privoxy on or off</ulink>
1533 ▪ <ulink
1534 url="https://www.privoxy.org/&p-version;/user-manual/">Documentation</ulink>
1542 This should be self-explanatory. Note the first item leads to an editor for the
1543 <link linkend="actions-file">actions files</link>, which is where the ad, banner,
1544 cookie, and URL blocking magic is configured as well as other advanced features of
1545 <application>Privoxy</application>. This is an easy way to adjust various
1546 aspects of <application>Privoxy</application> configuration. The actions
1547 file, and other configuration files, are explained in detail below.
1551 <quote>Toggle Privoxy On or Off</quote> is handy for sites that might
1552 have problems with your current actions and filters. You can in fact use
1553 it as a test to see whether it is <application>Privoxy</application>
1554 causing the problem or not. <application>Privoxy</application> continues
1555 to run as a proxy in this case, but all manipulation is disabled, i.e.
1556 <application>Privoxy</application> acts like a normal forwarding proxy.
1560 Note that several of the features described above are disabled by default
1561 in <application>Privoxy</application> 3.0.7 beta and later.
1563 <ulink url="config.html">configuration file</ulink> to learn why
1564 and in which cases it's safe to enable them again.
1569 <!-- ~ End section ~ -->
1574 <!-- ~~~~~ New section ~~~~~ -->
1576 <sect2 id="confoverview">
1577 <title>Configuration Files Overview</title>
1579 For Unix, *BSD and GNU/Linux, all configuration files are located in
1580 <filename>/etc/privoxy/</filename> by default. For MS Windows and OS/2
1581 these are all in the same directory as the
1582 <application>Privoxy</application> executable. <![%p-not-stable;[ The name
1583 and number of configuration files has changed from previous versions, and is
1584 subject to change as development progresses.]]>
1588 The installed defaults provide a reasonable starting point, though
1589 some settings may be aggressive by some standards. For the time being, the
1590 principle configuration files are:
1597 The <link linkend="config">main configuration file</link> is named <filename>config</filename>
1598 on GNU/Linux, Unix, BSD, and OS/2, and <filename>config.txt</filename>
1599 on Windows. This is a required file.
1605 <filename>match-all.action</filename> is used to define which <quote>actions</quote>
1606 relating to banner-blocking, images, pop-ups, content modification, cookie handling
1607 etc should be applied by default. It should be the first actions file loaded.
1610 <filename>default.action</filename> defines many exceptions (both positive and negative)
1611 from the default set of actions that's configured in <filename>match-all.action</filename>.
1612 It should be the second actions file loaded and shouldn't be edited by the user.
1615 Multiple actions files may be defined in <filename>config</filename>. These
1616 are processed in the order they are defined. Local customizations and locally
1617 preferred exceptions to the default policies as defined in
1618 <filename>match-all.action</filename> (which you will most probably want
1619 to define sooner or later) are best applied in <filename>user.action</filename>,
1620 where you can preserve them across upgrades. The file isn't installed by all
1621 installers, but you can easily create it yourself with a text editor.
1624 There is also a web based editor that can be accessed from
1626 url="http://config.privoxy.org/show-status">http://config.privoxy.org/show-status</ulink>
1628 url="http://p.p/show-status">http://p.p/show-status</ulink>) for the
1629 various actions files.
1635 <quote>Filter files</quote> (the <link linkend="filter-file">filter
1636 file</link>) can be used to re-write the raw page content, including
1637 viewable text as well as embedded HTML and JavaScript, and whatever else
1638 lurks on any given web page. The filtering jobs are only pre-defined here;
1639 whether to apply them or not is up to the actions files.
1640 <filename>default.filter</filename> includes various filters made
1641 available for use by the developers. Some are much more intrusive than
1642 others, and all should be used with caution. You may define additional
1643 filter files in <filename>config</filename> as you can with
1644 actions files. We suggest <filename>user.filter</filename> for any
1645 locally defined filters or customizations.
1652 The syntax of the configuration and filter files may change between different
1653 Privoxy versions, unfortunately some enhancements cost backwards compatibility.
1654 <!-- Add link to documentation-->
1658 All files use the <quote><literal>#</literal></quote> character to denote a
1659 comment (the rest of the line will be ignored) and understand line continuation
1660 through placing a backslash ("<literal>\</literal>") as the very last character
1661 in a line. If the <literal>#</literal> is preceded by a backslash, it looses
1662 its special function. Placing a <literal>#</literal> in front of an otherwise
1663 valid configuration line to prevent it from being interpreted is called "commenting
1664 out" that line. Blank lines are ignored.
1668 The actions files and filter files
1669 can use Perl style <link linkend="regex">regular expressions</link> for
1670 maximum flexibility.
1674 After making any changes, there is no need to restart
1675 <application>Privoxy</application> in order for the changes to take
1676 effect. <application>Privoxy</application> detects such changes
1677 automatically. Note, however, that it may take one or two additional
1678 requests for the change to take effect. When changing the listening address
1679 of <application>Privoxy</application>, these <quote>wake up</quote> requests
1680 must obviously be sent to the <emphasis>old</emphasis> listening address.
1685 While under development, the configuration content is subject to change.
1686 The below documentation may not be accurate by the time you read this.
1687 Also, what constitutes a <quote>default</quote> setting, may change, so
1688 please check all your configuration files on important issues.
1694 <!-- ~ End section ~ -->
1697 <!-- ~~~~~~~~ New section Header ~~~~~~~~~ -->
1699 <!-- **************************************************** -->
1700 <!-- Include config.sgml here -->
1701 <!-- This is where the entire config file is detailed. -->
1703 <!-- end include -->
1706 <!-- ~ End section ~ -->
1710 <!-- ~~~~~~~~ New section Header ~~~~~~~~~ -->
1712 <sect1 id="actions-file"><title>Actions Files</title>
1716 XXX: similar descriptions are in the Configuration Files sections.
1717 We should only describe them at one place.
1720 The actions files are used to define what <emphasis>actions</emphasis>
1721 <application>Privoxy</application> takes for which URLs, and thus determines
1722 how ad images, cookies and various other aspects of HTTP content and
1723 transactions are handled, and on which sites (or even parts thereof).
1724 There are a number of such actions, with a wide range of functionality.
1725 Each action does something a little different.
1726 These actions give us a veritable arsenal of tools with which to exert
1727 our control, preferences and independence. Actions can be combined so that
1728 their effects are aggregated when applied against a given set of URLs.
1732 are three action files included with <application>Privoxy</application> with
1738 <filename>match-all.action</filename> - is used to define which
1739 <quote>actions</quote> relating to banner-blocking, images, pop-ups,
1740 content modification, cookie handling etc should be applied by default.
1741 It should be the first actions file loaded
1746 <filename>default.action</filename> - defines many exceptions (both
1747 positive and negative) from the default set of actions that's configured
1748 in <filename>match-all.action</filename>. It is a set of rules that should
1749 work reasonably well as-is for most users. This file is only supposed to
1750 be edited by the developers. It should be the second actions file loaded.
1755 <filename>user.action</filename> - is intended to be for local site
1756 preferences and exceptions. As an example, if your ISP or your bank
1757 has specific requirements, and need special handling, this kind of
1758 thing should go here. This file will not be upgraded.
1763 <guibutton>Edit</guibutton> <guibutton>Set to Cautious</guibutton> <guibutton>Set to Medium</guibutton> <guibutton>Set to Advanced</guibutton>
1766 These have increasing levels of aggressiveness <emphasis>and have no
1767 influence on your browsing unless you select them explicitly in the
1768 editor</emphasis>. A default installation should be pre-set to
1769 <literal>Cautious</literal>. New users should try this for a while before
1770 adjusting the settings to more aggressive levels. The more aggressive
1771 the settings, then the more likelihood there is of problems such as sites
1772 not working as they should.
1775 The <guibutton>Edit</guibutton> button allows you to turn each
1776 action on/off individually for fine-tuning. The <guibutton>Cautious</guibutton>
1777 button changes the actions list to low/safe settings which will activate
1778 ad blocking and a minimal set of &my-app;'s features, and subsequently
1779 there will be less of a chance for accidental problems. The
1780 <guibutton>Medium</guibutton> button sets the list to a medium level of
1781 other features and a low level set of privacy features. The
1782 <guibutton>Advanced</guibutton> button sets the list to a high level of
1783 ad blocking and medium level of privacy. See the chart below. The latter
1784 three buttons over-ride any changes via with the
1785 <guibutton>Edit</guibutton> button. More fine-tuning can be done in the
1786 lower sections of this internal page.
1789 While the actions file editor allows to enable these settings in all
1790 actions files, they are only supposed to be enabled in the first one
1791 to make sure you don't unintentionally overrule earlier rules.
1794 The default profiles, and their associated actions, as pre-defined in
1795 <filename>default.action</filename> are:
1797 <table frame=all><title>Default Configurations</title>
1798 <tgroup cols=4 align=left colsep=1 rowsep=1>
1799 <colspec colname=c1>
1800 <colspec colname=c2>
1801 <colspec colname=c3>
1802 <colspec colname=c4>
1805 <entry>Feature</entry>
1806 <entry>Cautious</entry>
1807 <entry>Medium</entry>
1808 <entry>Advanced</entry>
1813 <!-- <entry>f1</entry> -->
1814 <!-- <entry>f2</entry> -->
1815 <!-- <entry>f3</entry> -->
1816 <!-- <entry>f4</entry> -->
1822 <entry>Ad-blocking Aggressiveness</entry>
1823 <entry>medium</entry>
1829 <entry>Ad-filtering by size</entry>
1836 <entry>Ad-filtering by link</entry>
1842 <entry>Pop-up killing</entry>
1843 <entry>blocks only</entry>
1844 <entry>blocks only</entry>
1845 <entry>blocks only</entry>
1849 <entry>Privacy Features</entry>
1851 <entry>medium</entry>
1852 <entry>medium/high</entry>
1856 <entry>Cookie handling</entry>
1858 <entry>session-only</entry>
1863 <entry>Referer forging</entry>
1870 <entry>GIF de-animation</entry>
1877 <entry>Fast redirects</entry>
1884 <entry>HTML taming</entry>
1891 <entry>JavaScript taming</entry>
1898 <entry>Web-bug killing</entry>
1905 <entry>Image tag reordering</entry>
1919 The list of actions files to be used are defined in the main configuration
1920 file, and are processed in the order they are defined (e.g.
1921 <filename>default.action</filename> is typically processed before
1922 <filename>user.action</filename>). The content of these can all be viewed and
1924 url="http://config.privoxy.org/show-status">http://config.privoxy.org/show-status</ulink>.
1925 The over-riding principle when applying actions, is that the last action that
1926 matches a given URL wins. The broadest, most general rules go first
1927 (defined in <filename>default.action</filename>),
1928 followed by any exceptions (typically also in
1929 <filename>default.action</filename>), which are then followed lastly by any
1930 local preferences (typically in <emphasis>user</emphasis><filename>.action</filename>).
1931 Generally, <filename>user.action</filename> has the last word.
1935 An actions file typically has multiple sections. If you want to use
1936 <quote>aliases</quote> in an actions file, you have to place the (optional)
1937 <link linkend="aliases">alias section</link> at the top of that file.
1938 Then comes the default set of rules which will apply universally to all
1939 sites and pages (be <emphasis>very careful</emphasis> with using such a
1940 universal set in <filename>user.action</filename> or any other actions file after
1941 <filename>default.action</filename>, because it will override the result
1942 from consulting any previous file). And then below that,
1943 exceptions to the defined universal policies. You can regard
1944 <filename>user.action</filename> as an appendix to <filename>default.action</filename>,
1945 with the advantage that it is a separate file, which makes preserving your
1946 personal settings across <application>Privoxy</application> upgrades easier.
1950 Actions can be used to block anything you want, including ads, banners, or
1951 just some obnoxious URL whose content you would rather not see. Cookies can be accepted
1952 or rejected, or accepted only during the current browser session (i.e. not
1953 written to disk), content can be modified, some JavaScripts tamed, user-tracking
1954 fooled, and much more. See below for a <link linkend="actions">complete list
1958 <!-- ~~~~~ New section ~~~~~ -->
1959 <sect2 id="right-mix">
1960 <title>Finding the Right Mix</title>
1962 Note that some <link linkend="actions">actions</link>, like cookie suppression
1963 or script disabling, may render some sites unusable that rely on these
1964 techniques to work properly. Finding the right mix of actions is not always easy and
1965 certainly a matter of personal taste. And, things can always change, requiring
1966 refinements in the configuration. In general, it can be said that the more
1967 <quote>aggressive</quote> your default settings (in the top section of the
1968 actions file) are, the more exceptions for <quote>trusted</quote> sites you
1969 will have to make later. If, for example, you want to crunch all cookies per
1970 default, you'll have to make exceptions from that rule for sites that you
1971 regularly use and that require cookies for actually useful purposes, like maybe
1972 your bank, favorite shop, or newspaper.
1976 We have tried to provide you with reasonable rules to start from in the
1977 distribution actions files. But there is no general rule of thumb on these
1978 things. There just are too many variables, and sites are constantly changing.
1979 Sooner or later you will want to change the rules (and read this chapter again :).
1983 <!-- ~~~~~ New section ~~~~~ -->
1984 <sect2 id="how-to-edit">
1985 <title>How to Edit</title>
1987 The easiest way to edit the actions files is with a browser by
1988 using our browser-based editor, which can be reached from <ulink
1989 url="http://config.privoxy.org/show-status">http://config.privoxy.org/show-status</ulink>.
1990 Note: the config file option <link
1991 linkend="enable-edit-actions">enable-edit-actions</link> must be enabled for
1992 this to work. The editor allows both fine-grained control over every single
1993 feature on a per-URL basis, and easy choosing from wholesale sets of defaults
1994 like <quote>Cautious</quote>, <quote>Medium</quote> or
1995 <quote>Advanced</quote>. Warning: the <quote>Advanced</quote> setting is more
1996 aggressive, and will be more likely to cause problems for some sites.
1997 Experienced users only!
2001 If you prefer plain text editing to GUIs, you can of course also directly edit the
2002 the actions files with your favorite text editor. Look at
2003 <filename>default.action</filename> which is richly commented with many
2009 <sect2 id="actions-apply">
2010 <title>How Actions are Applied to Requests</title>
2012 Actions files are divided into sections. There are special sections,
2013 like the <quote><link linkend="aliases">alias</link></quote> sections which will
2014 be discussed later. For now let's concentrate on regular sections: They have a
2015 heading line (often split up to multiple lines for readability) which consist
2016 of a list of actions, separated by whitespace and enclosed in curly braces.
2017 Below that, there is a list of URL and tag patterns, each on a separate line.
2021 To determine which actions apply to a request, the URL of the request is
2022 compared to all URL patterns in each <quote>action file</quote>.
2023 Every time it matches, the list of applicable actions for the request is
2024 incrementally updated, using the heading of the section in which the
2025 pattern is located. The same is done again for tags and tag patterns later on.
2029 If multiple applying sections set the same action differently,
2030 the last match wins. If not, the effects are aggregated.
2031 E.g. a URL might match a regular section with a heading line of <literal>{
2032 +<link linkend="handle-as-image">handle-as-image</link> }</literal>,
2033 then later another one with just <literal>{
2034 +<link linkend="block">block</link> }</literal>, resulting
2035 in <emphasis>both</emphasis> actions to apply. And there may well be
2036 cases where you will want to combine actions together. Such a section then
2041 { +<literal>handle-as-image</literal> +<literal>block{Banner ads.}</literal> }
2042 # Block these as if they were images. Send no block page.
2044 media.example.com/.*banners
2045 .example.com/images/ads/</screen>
2048 You can trace this process for URL patterns and any given URL by visiting <ulink
2049 url="http://config.privoxy.org/show-url-info">http://config.privoxy.org/show-url-info</ulink>.
2053 Examples and more detail on this is provided in the Appendix, <link linkend="ACTIONSANAT">
2054 Troubleshooting: Anatomy of an Action</link> section.
2058 <!-- ~~~~~ New section ~~~~~ -->
2059 <sect2 id="af-patterns">
2060 <title>Patterns</title>
2062 As mentioned, <application>Privoxy</application> uses <quote>patterns</quote>
2063 to determine what <emphasis>actions</emphasis> might apply to which sites and
2064 pages your browser attempts to access. These <quote>patterns</quote> use wild
2065 card type <emphasis>pattern</emphasis> matching to achieve a high degree of
2066 flexibility. This allows one expression to be expanded and potentially match
2067 against many similar patterns.
2071 Generally, an URL pattern has the form
2072 <literal><host><port>/<path></literal>, where the
2073 <literal><host></literal>, the <literal><port></literal>
2074 and the <literal><path></literal> are optional. (This is why the special
2075 <literal>/</literal> pattern matches all URLs). Note that the protocol
2076 portion of the URL pattern (e.g. <literal>http://</literal>) should
2077 <emphasis>not</emphasis> be included in the pattern. This is assumed already!
2080 The pattern matching syntax is different for the host and path parts of
2081 the URL. The host part uses a simple globbing type matching technique,
2082 while the path part uses more flexible
2083 <ulink url="http://en.wikipedia.org/wiki/Regular_expressions"><quote>Regular
2084 Expressions</quote></ulink> (POSIX 1003.2).
2087 The port part of a pattern is a decimal port number preceded by a colon
2088 (<literal>:</literal>). If the host part contains a numerical IPv6 address,
2089 it has to be put into angle brackets
2090 (<literal><</literal>, <literal>></literal>).
2095 <term><literal>www.example.com/</literal></term>
2098 is a host-only pattern and will match any request to <literal>www.example.com</literal>,
2099 regardless of which document on that server is requested. So ALL pages in
2100 this domain would be covered by the scope of this action. Note that a
2101 simple <literal>example.com</literal> is different and would NOT match.
2106 <term><literal>www.example.com</literal></term>
2109 means exactly the same. For host-only patterns, the trailing <literal>/</literal> may
2115 <term><literal>www.example.com/index.html</literal></term>
2118 matches all the documents on <literal>www.example.com</literal>
2119 whose name starts with <literal>/index.html</literal>.
2124 <term><literal>www.example.com/index.html$</literal></term>
2127 matches only the single document <literal>/index.html</literal>
2128 on <literal>www.example.com</literal>.
2133 <term><literal>/index.html$</literal></term>
2136 matches the document <literal>/index.html</literal>, regardless of the domain,
2137 i.e. on <emphasis>any</emphasis> web server anywhere.
2142 <term><literal>/</literal></term>
2145 Matches any URL because there's no requirement for either the
2146 domain or the path to match anything.
2151 <term><literal>:8000/</literal></term>
2154 Matches any URL pointing to TCP port 8000.
2159 <term><literal>10.0.0.1/</literal></term>
2162 Matches any URL with the host address <literal>10.0.0.1</literal>.
2163 (Note that the real URL uses plain brackets, not angle brackets.)
2168 <term><literal><2001:db8::1>/</literal></term>
2171 Matches any URL with the host address <literal>2001:db8::1</literal>.
2172 (Note that the real URL uses plain brackets, not angle brackets.)
2177 <term><literal>index.html</literal></term>
2180 matches nothing, since it would be interpreted as a domain name and
2181 there is no top-level domain called <literal>.html</literal>. So its
2189 <!-- ~~~~~ New section ~~~~~ -->
2190 <sect3 id="host-pattern"><title>The Host Pattern</title>
2193 The matching of the host part offers some flexible options: if the
2194 host pattern starts or ends with a dot, it becomes unanchored at that end.
2195 The host pattern is often referred to as domain pattern as it is usually
2196 used to match domain names and not IP addresses.
2202 <term><literal>.example.com</literal></term>
2205 matches any domain with first-level domain <literal>com</literal>
2206 and second-level domain <literal>example</literal>.
2207 For example <literal>www.example.com</literal>,
2208 <literal>example.com</literal> and <literal>foo.bar.baz.example.com</literal>.
2209 Note that it wouldn't match if the second-level domain was <literal>another-example</literal>.
2214 <term><literal>www.</literal></term>
2217 matches any domain that <emphasis>STARTS</emphasis> with
2218 <literal>www.</literal> (It also matches the domain
2219 <literal>www</literal> but most of the time that doesn't matter.)
2224 <term><literal>.example.</literal></term>
2227 matches any domain that <emphasis>CONTAINS</emphasis> <literal>.example.</literal>.
2228 And, by the way, also included would be any files or documents that exist
2229 within that domain since no path limitations are specified. (Correctly
2230 speaking: It matches any FQDN that contains <literal>example</literal> as
2231 a domain.) This might be <literal>www.example.com</literal>,
2232 <literal>news.example.de</literal>, or
2233 <literal>www.example.net/cgi/testing.pl</literal> for instance. All these
2241 Additionally, there are wild-cards that you can use in the domain names
2242 themselves. These work similarly to shell globbing type wild-cards:
2243 <quote>*</quote> represents zero or more arbitrary characters (this is
2245 <ulink url="http://en.wikipedia.org/wiki/Regular_expressions"><quote>Regular
2246 Expression</quote></ulink> based syntax of <quote>.*</quote>),
2247 <quote>?</quote> represents any single character (this is equivalent to the
2248 regular expression syntax of a simple <quote>.</quote>), and you can define
2249 <quote>character classes</quote> in square brackets which is similar to
2250 the same regular expression technique. All of this can be freely mixed:
2255 <term><literal>ad*.example.com</literal></term>
2258 matches <quote>adserver.example.com</quote>,
2259 <quote>ads.example.com</quote>, etc but not <quote>sfads.example.com</quote>
2264 <term><literal>*ad*.example.com</literal></term>
2267 matches all of the above, and then some.
2272 <term><literal>.?pix.com</literal></term>
2275 matches <literal>www.ipix.com</literal>,
2276 <literal>pictures.epix.com</literal>, <literal>a.b.c.d.e.upix.com</literal> etc.
2281 <term><literal>www[1-9a-ez].example.c*</literal></term>
2284 matches <literal>www1.example.com</literal>,
2285 <literal>www4.example.cc</literal>, <literal>wwwd.example.cy</literal>,
2286 <literal>wwwz.example.com</literal> etc., but <emphasis>not</emphasis>
2287 <literal>wwww.example.com</literal>.
2294 While flexible, this is not the sophistication of full regular expression based syntax.
2298 When compiled with FEATURE_PCRE_HOST_PATTERNS patterns can be prefixed with
2299 <quote>PCRE-HOST-PATTERN:</quote> in which case full regular expression
2300 (PCRE) can be used for the host pattern as well.
2305 <!-- ~ End section ~ -->
2308 <!-- ~~~~~ New section ~~~~~ -->
2309 <sect3 id="path-pattern"><title>The Path Pattern</title>
2312 <application>Privoxy</application> uses <quote>modern</quote> POSIX 1003.2
2313 <ulink url="http://en.wikipedia.org/wiki/Regular_expressions"><quote>Regular
2314 Expressions</quote></ulink> for matching the path portion (after the slash),
2315 and is thus more flexible.
2319 There is an <link linkend="regex">Appendix</link> with a brief quick-start into regular
2320 expressions, you also might want to have a look at your operating system's documentation
2321 on regular expressions (try <literal>man re_format</literal>).
2325 Note that the path pattern is automatically left-anchored at the <quote>/</quote>,
2326 i.e. it matches as if it would start with a <quote>^</quote> (regular expression speak
2327 for the beginning of a line).
2331 Please also note that matching in the path is <emphasis>CASE INSENSITIVE</emphasis>
2332 by default, but you can switch to case sensitive at any point in the pattern by using the
2333 <quote>(?-i)</quote> switch: <literal>www.example.com/(?-i)PaTtErN.*</literal> will match
2334 only documents whose path starts with <literal>PaTtErN</literal> in
2335 <emphasis>exactly</emphasis> this capitalization.
2340 <term><literal>.example.com/.*</literal></term>
2343 Is equivalent to just <quote>.example.com</quote>, since any documents
2344 within that domain are matched with or without the <quote>.*</quote>
2345 regular expression. This is redundant
2350 <term><literal>.example.com/.*/index.html$</literal></term>
2353 Will match any page in the domain of <quote>example.com</quote> that is
2354 named <quote>index.html</quote>, and that is part of some path. For
2355 example, it matches <quote>www.example.com/testing/index.html</quote> but
2356 NOT <quote>www.example.com/index.html</quote> because the regular
2357 expression called for at least two <quote>/'s</quote>, thus the path
2358 requirement. It also would match
2359 <quote>www.example.com/testing/index_html</quote>, because of the
2360 special meta-character <quote>.</quote>.
2365 <term><literal>.example.com/(.*/)?index\.html$</literal></term>
2368 This regular expression is conditional so it will match any page
2369 named <quote>index.html</quote> regardless of path which in this case can
2370 have one or more <quote>/'s</quote>. And this one must contain exactly
2371 <quote>.html</quote> (and end with that!).
2376 <term><literal>.example.com/(.*/)(ads|banners?|junk)</literal></term>
2379 This regular expression will match any path of <quote>example.com</quote>
2380 that contains any of the words <quote>ads</quote>, <quote>banner</quote>,
2381 <quote>banners</quote> (because of the <quote>?</quote>) or <quote>junk</quote>.
2382 The path does not have to end in these words, just contain them.
2383 The path has to contain at least two slashes (including the one at the beginning).
2388 <term><literal>.example.com/(.*/)(ads|banners?|junk)/.*\.(jpe?g|gif|png)$</literal></term>
2391 This is very much the same as above, except now it must end in either
2392 <quote>.jpg</quote>, <quote>.jpeg</quote>, <quote>.gif</quote> or <quote>.png</quote>. So this
2393 one is limited to common image formats.
2400 There are many, many good examples to be found in <filename>default.action</filename>,
2401 and more tutorials below in <link linkend="regex">Appendix on regular expressions</link>.
2406 <!-- ~ End section ~ -->
2409 <!-- ~~~~~ New section ~~~~~ -->
2410 <sect3 id="tag-pattern"><title>The Request Tag Pattern</title>
2413 Request tag patterns are used to change the applying actions based on the
2414 request's tags. Tags can be created based on HTTP headers with either
2415 the <link linkend="CLIENT-HEADER-TAGGER">client-header-tagger</link>
2416 or the <link linkend="SERVER-HEADER-TAGGER">server-header-tagger</link> action.
2420 Request tag patterns have to start with <quote>TAG:</quote>, so &my-app;
2421 can tell them apart from other patterns. Everything after the colon
2422 including white space, is interpreted as a regular expression with
2423 path pattern syntax, except that tag patterns aren't left-anchored
2424 automatically (&my-app; doesn't silently add a <quote>^</quote>,
2425 you have to do it yourself if you need it).
2429 To match all requests that are tagged with <quote>foo</quote>
2430 your pattern line should be <quote>TAG:^foo$</quote>,
2431 <quote>TAG:foo</quote> would work as well, but it would also
2432 match requests whose tags contain <quote>foo</quote> somewhere.
2433 <quote>TAG: foo</quote> wouldn't work as it requires white space.
2437 Sections can contain URL and request tag patterns at the same time,
2438 but request tag patterns are checked after the URL patterns and thus
2439 always overrule them, even if they are located before the URL patterns.
2443 Once a new request tag is added, Privoxy checks right away if it's matched by one
2444 of the request tag patterns and updates the action settings accordingly. As a result
2445 request tags can be used to activate other tagger actions, as long as these other
2446 taggers look for headers that haven't already be parsed.
2450 For example you could tag client requests which use the
2451 <literal>POST</literal> method,
2452 then use this tag to activate another tagger that adds a tag if cookies
2453 are sent, and then use a block action based on the cookie tag. This allows
2454 the outcome of one action, to be input into a subsequent action. However if
2455 you'd reverse the position of the described taggers, and activated the
2456 method tagger based on the cookie tagger, no method tags would be created.
2457 The method tagger would look for the request line, but at the time
2458 the cookie tag is created, the request line has already been parsed.
2462 While this is a limitation you should be aware of, this kind of
2463 indirection is seldom needed anyway and even the example doesn't
2464 make too much sense.
2469 <!-- ~~~~~ New section ~~~~~ -->
2470 <sect3 id="negative-tag-patterns"><title>The Negative Request Tag Patterns</title>
2473 To match requests that do not have a certain request tag, specify a negative tag pattern
2474 by prefixing the tag pattern line with either <quote>NO-REQUEST-TAG:</quote>
2475 or <quote>NO-RESPONSE-TAG:</quote> instead of <quote>TAG:</quote>.
2479 Negative request tag patterns created with <quote>NO-REQUEST-TAG:</quote> are checked
2480 after all client headers are scanned, the ones created with <quote>NO-RESPONSE-TAG:</quote>
2481 are checked after all server headers are scanned. In both cases all the created
2482 tags are considered.
2486 <!-- ~~~~~ New section ~~~~~ -->
2487 <sect3 id="client-tag-pattern"><title>The Client Tag Pattern</title>
2489 <!-- XXX: This section contains duplicates content from the
2490 client-specific-tag documentation. -->
2494 This is an experimental feature. The syntax is likely to change in future versions.
2499 Client tag patterns are not set based on HTTP headers but based on
2500 the client's IP address. Users can enable them themselves, but the
2501 Privoxy admin controls which tags are available and what their effect
2506 After a client-specific tag has been defined with the
2507 <link linkend="client-specific-tag">client-specific-tag</link>,
2508 directive, action sections can be activated based on the tag by using a
2509 CLIENT-TAG pattern. The CLIENT-TAG pattern is evaluated at the same priority
2510 as URL patterns, as a result the last matching pattern wins. Tags that
2511 are created based on client or server headers are evaluated later on
2512 and can overrule CLIENT-TAG and URL patterns!
2515 The tag is set for all requests that come from clients that requested
2516 it to be set. Note that "clients" are differentiated by IP address,
2517 if the IP address changes the tag has to be requested again.
2520 Clients can request tags to be set by using the CGI interface <ulink
2521 url="http://config.privoxy.org/client-tags">http://config.privoxy.org/client-tags</ulink>.
2529 # If the admin defined the client-specific-tag circumvent-blocks,
2530 # and the request comes from a client that previously requested
2531 # the tag to be set, overrule all previous +block actions that
2532 # are enabled based on URL to CLIENT-TAG patterns.
2534 CLIENT-TAG:^circumvent-blocks$
2536 # This section is not overruled because it's located after
2538 {+block{Nobody is supposed to request this.}}
2539 example.org/blocked-example-page</screen>
2545 <!-- ~ End section ~ -->
2548 <!-- ~~~~~ New section ~~~~~ -->
2550 <sect2 id="actions">
2551 <title>Actions</title>
2553 All actions are disabled by default, until they are explicitly enabled
2554 somewhere in an actions file. Actions are turned on if preceded with a
2555 <quote>+</quote>, and turned off if preceded with a <quote>-</quote>. So a
2556 <literal>+action</literal> means <quote>do that action</quote>, e.g.
2557 <literal>+block</literal> means <quote>please block URLs that match the
2558 following patterns</quote>, and <literal>-block</literal> means <quote>don't
2559 block URLs that match the following patterns, even if <literal>+block</literal>
2560 previously applied.</quote>
2564 Again, actions are invoked by placing them on a line, enclosed in curly braces and
2565 separated by whitespace, like in
2566 <literal>{+some-action -some-other-action{some-parameter}}</literal>,
2567 followed by a list of URL patterns, one per line, to which they apply.
2568 Together, the actions line and the following pattern lines make up a section
2569 of the actions file.
2573 Actions fall into three categories:
2579 Boolean, i.e the action can only be <quote>enabled</quote> or
2580 <quote>disabled</quote>. Syntax:
2583 +<replaceable class="function">name</replaceable> # enable action <replaceable class="parameter">name</replaceable>
2584 -<replaceable class="function">name</replaceable> # disable action <replaceable class="parameter">name</replaceable></screen>
2586 Example: <literal>+handle-as-image</literal>
2593 Parameterized, where some value is required in order to enable this type of action.
2597 +<replaceable class="function">name</replaceable>{<replaceable class="parameter">param</replaceable>} # enable action and set parameter to <replaceable class="parameter">param</replaceable>,
2598 # overwriting parameter from previous match if necessary
2599 -<replaceable class="function">name</replaceable> # disable action. The parameter can be omitted</screen>
2601 Note that if the URL matches multiple positive forms of a parameterized action,
2602 the last match wins, i.e. the params from earlier matches are simply ignored.
2605 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>
2611 Multi-value. These look exactly like parameterized actions,
2612 but they behave differently: If the action applies multiple times to the
2613 same URL, but with different parameters, <emphasis>all</emphasis> the parameters
2614 from <emphasis>all</emphasis> matches are remembered. This is used for actions
2615 that can be executed for the same request repeatedly, like adding multiple
2616 headers, or filtering through multiple filters. Syntax:
2619 +<replaceable class="function">name</replaceable>{<replaceable class="parameter">param</replaceable>} # enable action and add <replaceable class="parameter">param</replaceable> to the list of parameters
2620 -<replaceable class="function">name</replaceable>{<replaceable class="parameter">param</replaceable>} # remove the parameter <replaceable class="parameter">param</replaceable> from the list of parameters
2621 # If it was the last one left, disable the action.
2622 <replaceable class="parameter">-name</replaceable> # disable this action completely and remove all parameters from the list</screen>
2624 Examples: <literal>+add-header{X-Fun-Header: Some text}</literal> and
2625 <literal>+filter{html-annoyances}</literal>
2632 If nothing is specified in any actions file, no <quote>actions</quote> are
2633 taken. So in this case <application>Privoxy</application> would just be a
2634 normal, non-blocking, non-filtering proxy. You must specifically enable the
2635 privacy and blocking features you need (although the provided default actions
2636 files will give a good starting point).
2640 Later defined action sections always over-ride earlier ones of the same type.
2641 So exceptions to any rules you make, should come in the latter part of the file (or
2642 in a file that is processed later when using multiple actions files such
2643 as <filename>user.action</filename>). For multi-valued actions, the actions
2644 are applied in the order they are specified. Actions files are processed in
2645 the order they are defined in <filename>config</filename> (the default
2646 installation has three actions files). It also quite possible for any given
2647 URL to match more than one <quote>pattern</quote> (because of wildcards and
2648 regular expressions), and thus to trigger more than one set of actions! Last
2652 <!-- start actions listing -->
2654 The list of valid <application>Privoxy</application> actions are:
2658 <!-- ********************************************************** -->
2659 <!-- Please note the below defined actions use id's that are -->
2660 <!-- probably linked from other places, so please don't change. -->
2662 <!-- ********************************************************** -->
2665 <!-- ~~~~~ New section ~~~~~ -->
2667 <sect3 renderas="sect4" id="add-header">
2668 <title>add-header</title>
2672 <term>Typical use:</term>
2674 <para>Confuse log analysis, custom applications</para>
2679 <term>Effect:</term>
2682 Sends a user defined HTTP header to the web server.
2689 <!-- boolean, parameterized, Multi-value -->
2691 <para>Multi-value.</para>
2696 <term>Parameter:</term>
2699 Any string value is possible. Validity of the defined HTTP headers is not checked.
2700 It is recommended that you use the <quote><literal>X-</literal></quote> prefix
2710 This action may be specified multiple times, in order to define multiple
2711 headers. This is rarely needed for the typical user. If you don't know what
2712 <quote>HTTP headers</quote> are, you definitely don't need to worry about this
2716 Headers added by this action are not modified by other actions.
2722 <term>Example usage:</term>
2724 <screen># Add a DNT ("Do not track") header to all requests,
2725 # event to those that already have one.
2727 # This is just an example, not a recommendation.
2729 # There is no reason to believe that user-tracking websites care
2730 # about the DNT header and depending on the User-Agent, adding the
2731 # header may make user-tracking easier.
2732 {+add-header{DNT: 1}}
2740 <!-- ~~~~~ New section ~~~~~ -->
2741 <sect3 renderas="sect4" id="block">
2742 <title>block</title>
2746 <term>Typical use:</term>
2748 <para>Block ads or other unwanted content</para>
2753 <term>Effect:</term>
2756 Requests for URLs to which this action applies are blocked, i.e. the
2757 requests are trapped by &my-app; and the requested URL is never retrieved,
2758 but is answered locally with a substitute page or image, as determined by
2760 linkend="handle-as-image">handle-as-image</link></literal>,
2762 linkend="set-image-blocker">set-image-blocker</link></literal>, and
2764 linkend="handle-as-empty-document">handle-as-empty-document</link></literal> actions.
2772 <!-- boolean, parameterized, Multi-value -->
2774 <para>Parameterized.</para>
2779 <term>Parameter:</term>
2781 <para>A block reason that should be given to the user.</para>
2789 <application>Privoxy</application> sends a special <quote>BLOCKED</quote> page
2790 for requests to blocked pages. This page contains the block reason given as
2791 parameter, a link to find out why the block action applies, and a click-through
2792 to the blocked content (the latter only if the force feature is available and
2796 A very important exception occurs if <emphasis>both</emphasis>
2797 <literal>block</literal> and <literal><link linkend="handle-as-image">handle-as-image</link></literal>,
2798 apply to the same request: it will then be replaced by an image. If
2799 <literal><link linkend="set-image-blocker">set-image-blocker</link></literal>
2800 (see below) also applies, the type of image will be determined by its parameter,
2801 if not, the standard checkerboard pattern is sent.
2804 It is important to understand this process, in order
2805 to understand how <application>Privoxy</application> deals with
2806 ads and other unwanted content. Blocking is a core feature, and one
2807 upon which various other features depend.
2810 The <literal><link linkend="filter">filter</link></literal>
2811 action can perform a very similar task, by <quote>blocking</quote>
2812 banner images and other content through rewriting the relevant URLs in the
2813 document's HTML source, so they don't get requested in the first place.
2814 Note that this is a totally different technique, and it's easy to confuse the two.
2820 <term>Example usage (section):</term>
2822 <screen>{+block{No nasty stuff for you.}}
2823 # Block and replace with "blocked" page
2824 .nasty-stuff.example.com
2826 {+block{Doubleclick banners.} +handle-as-image}
2827 # Block and replace with image
2831 {+block{Layered ads.} +handle-as-empty-document}
2832 # Block and then ignore
2833 adserver.example.net/.*\.js$</screen>
2842 <!-- ~~~~~ New section ~~~~~ -->
2843 <sect3 renderas="sect4" id="change-x-forwarded-for">
2844 <title>change-x-forwarded-for</title>
2848 <term>Typical use:</term>
2850 <para>Improve privacy by not forwarding the source of the request in the HTTP headers.</para>
2855 <term>Effect:</term>
2858 Deletes the <quote>X-Forwarded-For:</quote> HTTP header from the client request,
2866 <!-- Boolean, Parameterized, Multi-value -->
2868 <para>Parameterized.</para>
2873 <term>Parameter:</term>
2877 <para><quote>block</quote> to delete the header.</para>
2881 <quote>add</quote> to create the header (or append
2882 the client's IP address to an already existing one).
2893 It is safe and recommended to use <literal>block</literal>.
2896 Forwarding the source address of the request may make
2897 sense in some multi-user setups but is also a privacy risk.
2902 <term>Example usage:</term>
2904 <screen>+change-x-forwarded-for{block}</screen>
2910 <!-- ~~~~~ New section ~~~~~ -->
2911 <sect3 renderas="sect4" id="client-header-filter">
2912 <title>client-header-filter</title>
2916 <term>Typical use:</term>
2919 Rewrite or remove single client headers.
2925 <term>Effect:</term>
2928 All client headers to which this action applies are filtered on-the-fly through
2929 the specified regular expression based substitutions.
2936 <!-- boolean, parameterized, Multi-value -->
2938 <para>Multi-value.</para>
2943 <term>Parameter:</term>
2946 The name of a client-header filter, as defined in one of the
2947 <link linkend="filter-file">filter files</link>.
2956 Client-header filters are applied to each header on its own, not to
2957 all at once. This makes it easier to diagnose problems, but on the downside
2958 you can't write filters that only change header x if header y's value is z.
2959 You can do that by using tags though.
2962 Client-header filters are executed after the other header actions have finished
2963 and use their output as input.
2966 If the request URI gets changed, &my-app; will detect that and use the new
2967 one. This can be used to rewrite the request destination behind the client's
2968 back, for example to specify a Tor exit relay for certain requests.
2971 Please refer to the <link linkend="filter-file">filter file chapter</link>
2972 to learn which client-header filters are available by default, and how to
2980 <term>Example usage (section):</term>
2983 # Hide Tor exit notation in Host and Referer Headers
2984 {+client-header-filter{hide-tor-exit-notation}}
2994 <!-- ~~~~~ New section ~~~~~ -->
2995 <sect3 renderas="sect4" id="client-header-tagger">
2996 <title>client-header-tagger</title>
3000 <term>Typical use:</term>
3003 Block requests based on their headers.
3009 <term>Effect:</term>
3012 Client headers to which this action applies are filtered on-the-fly through
3013 the specified regular expression based substitutions, the result is used as
3021 <!-- boolean, parameterized, Multi-value -->
3023 <para>Multi-value.</para>
3028 <term>Parameter:</term>
3031 The name of a client-header tagger, as defined in one of the
3032 <link linkend="filter-file">filter files</link>.
3041 Client-header taggers are applied to each header on its own,
3042 and as the header isn't modified, each tagger <quote>sees</quote>
3046 Client-header taggers are the first actions that are executed
3047 and their tags can be used to control every other action.
3053 <term>Example usage (section):</term>
3056 # Tag every request with the User-Agent header
3057 {+client-header-tagger{user-agent}}
3060 # Tagging itself doesn't change the action
3061 # settings, sections with TAG patterns do:
3063 # If it's a download agent, use a different forwarding proxy,
3064 # show the real User-Agent and make sure resume works.
3065 {+forward-override{forward-socks5 10.0.0.2:2222 .} \
3066 -hide-if-modified-since \
3067 -overwrite-last-modified \
3072 TAG:^User-Agent: NetBSD-ftp/
3073 TAG:^User-Agent: Novell ZYPP Installer
3074 TAG:^User-Agent: RPM APT-HTTP/
3075 TAG:^User-Agent: fetch libfetch/
3076 TAG:^User-Agent: Ubuntu APT-HTTP/
3077 TAG:^User-Agent: MPlayer/
3081 # Tag all requests with the Range header set
3082 {+client-header-tagger{range-requests}}
3085 # Disable filtering for the tagged requests.
3087 # With filtering enabled Privoxy would remove the Range headers
3088 # to be able to filter the whole response. The downside is that
3089 # it prevents clients from resuming downloads or skipping over
3090 # parts of multimedia files.
3091 {-filter -deanimate-gifs}
3096 # Tag all requests with the client IP address
3098 # (Technically the client IP address isn't included in the
3099 # client headers but client-header taggers can set it anyway.
3100 # For details see the tagger in default.filter)
3101 {+client-header-tagger{client-ip-address}}
3104 # Change forwarding settings for requests coming from address 10.0.0.1
3105 {+forward-override{forward-socks5 127.0.1.2:2222 .}}
3106 TAG:^IP-ADDRESS: 10\.0\.0\.1$
3115 <!-- ~~~~~ New section ~~~~~ -->
3116 <sect3 renderas="sect4" id="content-type-overwrite">
3117 <title>content-type-overwrite</title>
3121 <term>Typical use:</term>
3123 <para>Stop useless download menus from popping up, or change the browser's rendering mode</para>
3128 <term>Effect:</term>
3131 Replaces the <quote>Content-Type:</quote> HTTP server header.
3138 <!-- Boolean, Parameterized, Multi-value -->
3140 <para>Parameterized.</para>
3145 <term>Parameter:</term>
3157 The <quote>Content-Type:</quote> HTTP server header is used by the
3158 browser to decide what to do with the document. The value of this
3159 header can cause the browser to open a download menu instead of
3160 displaying the document by itself, even if the document's format is
3161 supported by the browser.
3164 The declared content type can also affect which rendering mode
3165 the browser chooses. If XHTML is delivered as <quote>text/html</quote>,
3166 many browsers treat it as yet another broken HTML document.
3167 If it is send as <quote>application/xml</quote>, browsers with
3168 XHTML support will only display it, if the syntax is correct.
3171 If you see a web site that proudly uses XHTML buttons, but sets
3172 <quote>Content-Type: text/html</quote>, you can use &my-app;
3173 to overwrite it with <quote>application/xml</quote> and validate
3174 the web master's claim inside your XHTML-supporting browser.
3175 If the syntax is incorrect, the browser will complain loudly.
3178 You can also go the opposite direction: if your browser prints
3179 error messages instead of rendering a document falsely declared
3180 as XHTML, you can overwrite the content type with
3181 <quote>text/html</quote> and have it rendered as broken HTML document.
3184 By default <literal>content-type-overwrite</literal> only replaces
3185 <quote>Content-Type:</quote> headers that look like some kind of text.
3186 If you want to overwrite it unconditionally, you have to combine it with
3187 <literal><link linkend="force-text-mode">force-text-mode</link></literal>.
3188 This limitation exists for a reason, think twice before circumventing it.
3191 Most of the time it's easier to replace this action with a custom
3192 <literal><link linkend="server-header-filter">server-header filter</link></literal>.
3193 It allows you to activate it for every document of a certain site and it will still
3194 only replace the content types you aimed at.
3197 Of course you can apply <literal>content-type-overwrite</literal>
3198 to a whole site and then make URL based exceptions, but it's a lot
3199 more work to get the same precision.
3205 <term>Example usage (sections):</term>
3207 <screen># Check if www.example.net/ really uses valid XHTML
3208 { +content-type-overwrite{application/xml} }
3211 # but leave the content type unmodified if the URL looks like a style sheet
3212 {-content-type-overwrite}
3213 www.example.net/.*\.css$
3214 www.example.net/.*style
3222 <!-- ~~~~~ New section ~~~~~ -->
3223 <sect3 renderas="sect4" id="crunch-client-header">
3227 <title>crunch-client-header</title>
3231 <term>Typical use:</term>
3233 <para>Remove a client header <application>Privoxy</application> has no dedicated action for.</para>
3238 <term>Effect:</term>
3241 Deletes every header sent by the client that contains the string the user supplied as parameter.
3248 <!-- Boolean, Parameterized, Multi-value -->
3250 <para>Parameterized.</para>
3255 <term>Parameter:</term>
3267 This action allows you to block client headers for which no dedicated
3268 <application>Privoxy</application> action exists.
3269 <application>Privoxy</application> will remove every client header that
3270 contains the string you supplied as parameter.
3273 Regular expressions are <emphasis>not supported</emphasis> and you can't
3274 use this action to block different headers in the same request, unless
3275 they contain the same string.
3278 <literal>crunch-client-header</literal> is only meant for quick tests.
3279 If you have to block several different headers, or only want to modify
3280 parts of them, you should use a
3281 <literal><link linkend="client-header-filter">client-header filter</link></literal>.
3285 Don't block any header without understanding the consequences.
3292 <term>Example usage (section):</term>
3294 <screen># Block the non-existent "Privacy-Violation:" client header
3295 { +crunch-client-header{Privacy-Violation:} }
3304 <!-- ~~~~~ New section ~~~~~ -->
3305 <sect3 renderas="sect4" id="crunch-if-none-match">
3306 <title>crunch-if-none-match</title>
3312 <term>Typical use:</term>
3314 <para>Prevent yet another way to track the user's steps between sessions.</para>
3319 <term>Effect:</term>
3322 Deletes the <quote>If-None-Match:</quote> HTTP client header.
3329 <!-- Boolean, Parameterized, Multi-value -->
3331 <para>Boolean.</para>
3336 <term>Parameter:</term>
3348 Removing the <quote>If-None-Match:</quote> HTTP client header
3349 is useful for filter testing, where you want to force a real
3350 reload instead of getting status code <quote>304</quote> which
3351 would cause the browser to use a cached copy of the page.
3354 It is also useful to make sure the header isn't used as a cookie
3355 replacement (unlikely but possible).
3358 Blocking the <quote>If-None-Match:</quote> header shouldn't cause any
3359 caching problems, as long as the <quote>If-Modified-Since:</quote> header
3360 isn't blocked or missing as well.
3363 It is recommended to use this action together with
3364 <literal><link linkend="hide-if-modified-since">hide-if-modified-since</link></literal>
3366 <literal><link linkend="overwrite-last-modified">overwrite-last-modified</link></literal>.
3372 <term>Example usage (section):</term>
3374 <screen># Let the browser revalidate cached documents but don't
3375 # allow the server to use the revalidation headers for user tracking.
3376 {+hide-if-modified-since{-60} \
3377 +overwrite-last-modified{randomize} \
3378 +crunch-if-none-match}
3387 <!-- ~~~~~ New section ~~~~~ -->
3388 <sect3 renderas="sect4" id="crunch-incoming-cookies">
3389 <title>crunch-incoming-cookies</title>
3393 <term>Typical use:</term>
3396 Prevent the web server from setting HTTP cookies on your system
3402 <term>Effect:</term>
3405 Deletes any <quote>Set-Cookie:</quote> HTTP headers from server replies.
3412 <!-- Boolean, Parameterized, Multi-value -->
3414 <para>Boolean.</para>
3419 <term>Parameter:</term>
3431 This action is only concerned with <emphasis>incoming</emphasis> HTTP cookies. For
3432 <emphasis>outgoing</emphasis> HTTP cookies, use
3433 <literal><link linkend="crunch-outgoing-cookies">crunch-outgoing-cookies</link></literal>.
3434 Use <emphasis>both</emphasis> to disable HTTP cookies completely.
3437 It makes <emphasis>no sense at all</emphasis> to use this action in conjunction
3438 with the <literal><link linkend="session-cookies-only">session-cookies-only</link></literal> action,
3439 since it would prevent the session cookies from being set. See also
3440 <literal><link linkend="filter-content-cookies">filter-content-cookies</link></literal>.
3446 <term>Example usage:</term>
3448 <screen>+crunch-incoming-cookies</screen>
3455 <!-- ~~~~~ New section ~~~~~ -->
3456 <sect3 renderas="sect4" id="crunch-server-header">
3457 <title>crunch-server-header</title>
3463 <term>Typical use:</term>
3465 <para>Remove a server header <application>Privoxy</application> has no dedicated action for.</para>
3470 <term>Effect:</term>
3473 Deletes every header sent by the server that contains the string the user supplied as parameter.
3480 <!-- Boolean, Parameterized, Multi-value -->
3482 <para>Parameterized.</para>
3487 <term>Parameter:</term>
3499 This action allows you to block server headers for which no dedicated
3500 <application>Privoxy</application> action exists. <application>Privoxy</application>
3501 will remove every server header that contains the string you supplied as parameter.
3504 Regular expressions are <emphasis>not supported</emphasis> and you can't
3505 use this action to block different headers in the same request, unless
3506 they contain the same string.
3509 <literal>crunch-server-header</literal> is only meant for quick tests.
3510 If you have to block several different headers, or only want to modify
3511 parts of them, you should use a custom
3512 <literal><link linkend="server-header-filter">server-header filter</link></literal>.
3516 Don't block any header without understanding the consequences.
3523 <term>Example usage (section):</term>
3525 <screen># Crunch server headers that try to prevent caching
3526 { +crunch-server-header{no-cache} }
3535 <!-- ~~~~~ New section ~~~~~ -->
3536 <sect3 renderas="sect4" id="crunch-outgoing-cookies">
3537 <title>crunch-outgoing-cookies</title>
3541 <term>Typical use:</term>
3544 Prevent the web server from reading any HTTP cookies from your system
3550 <term>Effect:</term>
3553 Deletes any <quote>Cookie:</quote> HTTP headers from client requests.
3560 <!-- Boolean, Parameterized, Multi-value -->
3562 <para>Boolean.</para>
3567 <term>Parameter:</term>
3579 This action is only concerned with <emphasis>outgoing</emphasis> HTTP cookies. For
3580 <emphasis>incoming</emphasis> HTTP cookies, use
3581 <literal><link linkend="crunch-incoming-cookies">crunch-incoming-cookies</link></literal>.
3582 Use <emphasis>both</emphasis> to disable HTTP cookies completely.
3585 It makes <emphasis>no sense at all</emphasis> to use this action in conjunction
3586 with the <literal><link linkend="session-cookies-only">session-cookies-only</link></literal> action,
3587 since it would prevent the session cookies from being read.
3593 <term>Example usage:</term>
3595 <screen>+crunch-outgoing-cookies</screen>
3603 <!-- ~~~~~ New section ~~~~~ -->
3604 <sect3 renderas="sect4" id="deanimate-gifs">
3605 <title>deanimate-gifs</title>
3609 <term>Typical use:</term>
3611 <para>Stop those annoying, distracting animated GIF images.</para>
3616 <term>Effect:</term>
3619 De-animate GIF animations, i.e. reduce them to their first or last image.
3626 <!-- boolean, parameterized, Multi-value -->
3628 <para>Parameterized.</para>
3633 <term>Parameter:</term>
3636 <quote>last</quote> or <quote>first</quote>
3645 This will also shrink the images considerably (in bytes, not pixels!). If
3646 the option <quote>first</quote> is given, the first frame of the animation
3647 is used as the replacement. If <quote>last</quote> is given, the last
3648 frame of the animation is used instead, which probably makes more sense for
3649 most banner animations, but also has the risk of not showing the entire
3650 last frame (if it is only a delta to an earlier frame).
3653 You can safely use this action with patterns that will also match non-GIF
3654 objects, because no attempt will be made at anything that doesn't look like
3661 <term>Example usage:</term>
3663 <screen>+deanimate-gifs{last}</screen>
3670 <!-- ~~~~~ New section ~~~~~ -->
3671 <sect3 renderas="sect4" id="delay-response">
3672 <title>delay-response</title>
3676 <term>Typical use:</term>
3678 <para>Delay responses to the client to reduce the load</para>
3683 <term>Effect:</term>
3686 Delays responses to the client by sending the response in ca. 10 byte chunks.
3693 <!-- boolean, parameterized, Multi-value -->
3695 <para>Parameterized.</para>
3700 <term>Parameter:</term>
3703 <quote>Number of milliseconds</quote>
3712 Sometimes when JavaScript code is used to fetch advertisements
3713 it doesn't respect Privoxy's blocks and retries to fetch the
3714 same resource again causing unnecessary load on the client.
3717 This action delays responses to the client and can be combined
3718 with <literal><link linkend="block">blocks</link></literal>
3719 to slow down the JavaScript code, thus reducing
3720 the load on the client.
3723 When used without <literal><link linkend="block">blocks</link></literal>
3724 the action can also be used to simulate a slow internet connection.
3730 <term>Example usage:</term>
3732 <screen>+delay-response{100}</screen>
3739 <!-- ~~~~~ New section ~~~~~ -->
3740 <sect3 renderas="sect4" id="downgrade-http-version">
3741 <title>downgrade-http-version</title>
3745 <term>Typical use:</term>
3747 <para>Work around (very rare) problems with HTTP/1.1</para>
3752 <term>Effect:</term>
3755 Downgrades HTTP/1.1 client requests and server replies to HTTP/1.0.
3762 <!-- boolean, parameterized, Multi-value -->
3764 <para>Boolean.</para>
3769 <term>Parameter:</term>
3781 This is a left-over from the time when <application>Privoxy</application>
3782 didn't support important HTTP/1.1 features well. It is left here for the
3783 unlikely case that you experience HTTP/1.1-related problems with some server
3787 Note that enabling this action is only a workaround. It should not
3788 be enabled for sites that work without it. While it shouldn't break
3789 any pages, it has an (usually negative) performance impact.
3792 If you come across a site where enabling this action helps, please report it,
3793 so the cause of the problem can be analyzed. If the problem turns out to be
3794 caused by a bug in <application>Privoxy</application> it should be
3795 fixed so the following release works without the work around.
3801 <term>Example usage (section):</term>
3803 <screen>{+downgrade-http-version}
3804 problem-host.example.com</screen>
3812 <!-- ~~~~~ New section ~~~~~ -->
3813 <sect3 renderas="sect4" id="external-filter">
3814 <title>external-filter</title>
3818 <term>Typical use:</term>
3820 <para>Modify content using a programming language of your choice.</para>
3825 <term>Effect:</term>
3828 All instances of text-based type, most notably HTML and JavaScript, to which
3829 this action applies, can be filtered on-the-fly through the specified external
3831 By default plain text documents are exempted from filtering, because web
3832 servers often use the <literal>text/plain</literal> MIME type for all files
3833 whose type they don't know.)
3840 <!-- boolean, parameterized, Multi-value -->
3842 <para>Multi-value.</para>
3847 <term>Parameter:</term>
3850 The name of an external content filter, as defined in the
3851 <link linkend="filter-file">filter file</link>.
3852 External filters can be defined in one or more files as defined by the
3853 <literal><link linkend="filterfile">filterfile</link></literal>
3854 option in the <link linkend="config">config file</link>.
3857 When used in its negative form,
3858 and without parameters, <emphasis>all</emphasis> filtering with external
3859 filters is completely disabled.
3868 External filters are scripts or programs that can modify the content in
3869 case common <literal><link linkend="filter">filters</link></literal>
3870 aren't powerful enough. With the exception that this action doesn't
3871 use pcrs-based filters, the notes in the
3872 <literal><link linkend="filter">filter</link></literal> section apply.
3876 Currently external filters are executed with &my-app;'s privileges.
3877 Only use external filters you understand and trust.
3881 This feature is experimental, the <literal><link
3882 linkend="external-filter-syntax">syntax</link></literal>
3883 may change in the future.
3890 <term>Example usage:</term>
3892 <screen>+external-filter{fancy-filter}</screen>
3898 <!-- ~~~~~ New section ~~~~~ -->
3899 <sect3 renderas="sect4" id="fast-redirects">
3900 <title>fast-redirects</title>
3904 <term>Typical use:</term>
3906 <para>Fool some click-tracking scripts and speed up indirect links.</para>
3911 <term>Effect:</term>
3914 Detects redirection URLs and redirects the browser without contacting
3915 the redirection server first.
3922 <!-- boolean, parameterized, Multi-value -->
3924 <para>Parameterized.</para>
3929 <term>Parameter:</term>
3934 <quote>simple-check</quote> to just search for the string <quote>http://</quote>
3935 to detect redirection URLs.
3940 <quote>check-decoded-url</quote> to decode URLs (if necessary) before searching
3941 for redirection URLs.
3952 Many sites, like yahoo.com, don't just link to other sites. Instead, they
3953 will link to some script on their own servers, giving the destination as a
3954 parameter, which will then redirect you to the final target. URLs
3955 resulting from this scheme typically look like:
3956 <quote>http://www.example.org/click-tracker.cgi?target=http%3a//www.example.net/</quote>.
3959 Sometimes, there are even multiple consecutive redirects encoded in the
3960 URL. These redirections via scripts make your web browsing more traceable,
3961 since the server from which you follow such a link can see where you go
3962 to. Apart from that, valuable bandwidth and time is wasted, while your
3963 browser asks the server for one redirect after the other. Plus, it feeds
3967 This feature is currently not very smart and is scheduled for improvement.
3968 If it is enabled by default, you will have to create some exceptions to
3969 this action. It can lead to failures in several ways:
3972 Not every URLs with other URLs as parameters is evil.
3973 Some sites offer a real service that requires this information to work.
3974 For example a validation service needs to know, which document to validate.
3975 <literal>fast-redirects</literal> assumes that every URL parameter that
3976 looks like another URL is a redirection target, and will always redirect to
3977 the last one. Most of the time the assumption is correct, but if it isn't,
3978 the user gets redirected anyway.
3981 Another failure occurs if the URL contains other parameters after the URL parameter.
3983 <quote>http://www.example.org/?redirect=http%3a//www.example.net/&foo=bar</quote>.
3984 contains the redirection URL <quote>http://www.example.net/</quote>,
3985 followed by another parameter. <literal>fast-redirects</literal> doesn't know that
3986 and will cause a redirect to <quote>http://www.example.net/&foo=bar</quote>.
3987 Depending on the target server configuration, the parameter will be silently ignored
3988 or lead to a <quote>page not found</quote> error. You can prevent this problem by
3989 first using the <literal><link linkend="redirect">redirect</link></literal> action
3990 to remove the last part of the URL, but it requires a little effort.
3993 To detect a redirection URL, <literal>fast-redirects</literal> only
3994 looks for the string <quote>http://</quote>, either in plain text
3995 (invalid but often used) or encoded as <quote>http%3a//</quote>.
3996 Some sites use their own URL encoding scheme, encrypt the address
3997 of the target server or replace it with a database id. In these cases
3998 <literal>fast-redirects</literal> is fooled and the request reaches the
3999 redirection server where it probably gets logged.
4005 <term>Example usage:</term>
4008 { +fast-redirects{simple-check} }
4011 { +fast-redirects{check-decoded-url} }
4012 another.example.com/testing</screen>
4020 <!-- ~~~~~ New section ~~~~~ -->
4021 <sect3 renderas="sect4" id="filter">
4022 <title>filter</title>
4026 <term>Typical use:</term>
4028 <para>Get rid of HTML and JavaScript annoyances, banner advertisements (by size),
4029 do fun text replacements, add personalized effects, etc.</para>
4034 <term>Effect:</term>
4037 All instances of text-based type, most notably HTML and JavaScript, to which
4038 this action applies, can be filtered on-the-fly through the specified regular
4039 expression based substitutions. (Note: as of version 3.0.3 plain text documents
4040 are exempted from filtering, because web servers often use the
4041 <literal>text/plain</literal> MIME type for all files whose type they don't know.)
4048 <!-- boolean, parameterized, Multi-value -->
4050 <para>Multi-value.</para>
4055 <term>Parameter:</term>
4058 The name of a content filter, as defined in the <link linkend="filter-file">filter file</link>.
4059 Filters can be defined in one or more files as defined by the
4060 <literal><link linkend="filterfile">filterfile</link></literal>
4061 option in the <link linkend="config">config file</link>.
4062 <filename>default.filter</filename> is the collection of filters
4063 supplied by the developers. Locally defined filters should go
4064 in their own file, such as <filename>user.filter</filename>.
4067 When used in its negative form,
4068 and without parameters, <emphasis>all</emphasis> filtering is completely disabled.
4077 For your convenience, there are a number of pre-defined filters available
4078 in the distribution filter file that you can use. See the examples below for
4082 Filtering requires buffering the page content, which may appear to
4083 slow down page rendering since nothing is displayed until all content has
4084 passed the filters. (The total time until the page is completely rendered
4085 doesn't change much, but it may be perceived as slower since the page is
4086 not incrementally displayed.)
4087 This effect will be more noticeable on slower connections.
4090 <quote>Rolling your own</quote>
4091 filters requires a knowledge of
4092 <ulink url="http://en.wikipedia.org/wiki/Regular_expressions"><quote>Regular
4093 Expressions</quote></ulink> and
4094 <ulink url="http://en.wikipedia.org/wiki/Html"><quote>HTML</quote></ulink>.
4095 This is very powerful feature, and potentially very intrusive.
4096 Filters should be used with caution, and where an equivalent
4097 <quote>action</quote> is not available.
4100 The amount of data that can be filtered is limited to the
4101 <literal><link linkend="buffer-limit">buffer-limit</link></literal>
4102 option in the main <link linkend="config">config file</link>. The
4103 default is 4096 KB (4 Megs). Once this limit is exceeded, the buffered
4104 data, and all pending data, is passed through unfiltered.
4107 Inappropriate MIME types, such as zipped files, are not filtered at all.
4108 (Again, only text-based types except plain text). Encrypted SSL data
4109 (from HTTPS servers) cannot be filtered either, since this would violate
4110 the integrity of the secure transaction. In some situations it might
4111 be necessary to protect certain text, like source code, from filtering
4112 by defining appropriate <literal>-filter</literal> exceptions.
4115 Compressed content can't be filtered either, but if &my-app;
4116 is compiled with zlib support and a supported compression algorithm
4117 is used (gzip or deflate), &my-app; can first decompress the content
4121 If you use a &my-app; version without zlib support, but want filtering to work on
4122 as much documents as possible, even those that would normally be sent compressed,
4123 you must use the <literal><link linkend="prevent-compression">prevent-compression</link></literal>
4124 action in conjunction with <literal>filter</literal>.
4127 Content filtering can achieve some of the same effects as the
4128 <literal><link linkend="block">block</link></literal>
4129 action, i.e. it can be used to block ads and banners. But the mechanism
4130 works quite differently. One effective use, is to block ad banners
4131 based on their size (see below), since many of these seem to be somewhat
4135 <link linkend="contact">Feedback</link> with suggestions for new or
4136 improved filters is particularly welcome!
4139 The below list has only the names and a one-line description of each
4140 predefined filter. There are <link linkend="predefined-filters">more
4141 verbose explanations</link> of what these filters do in the <link
4142 linkend="filter-file">filter file chapter</link>.
4148 <term>Example usage (with filters from the distribution <filename>default.filter</filename> file).
4149 See <link linkend="PREDEFINED-FILTERS">the Predefined Filters section</link> for
4150 more explanation on each:</term>
4153 <anchor id="filter-js-annoyances">
4155 <screen>+filter{js-annoyances} # Get rid of particularly annoying JavaScript abuse.</screen>
4157 <anchor id="filter-js-events">
4159 <screen>+filter{js-events} # Kill JavaScript event bindings and timers (Radically destructive! Only for extra nasty sites).</screen>
4161 <anchor id="filter-html-annoyances">
4163 <screen>+filter{html-annoyances} # Get rid of particularly annoying HTML abuse.</screen>
4165 <anchor id="filter-content-cookies">
4167 <screen>+filter{content-cookies} # Kill cookies that come in the HTML or JS content.</screen>
4169 <anchor id="filter-refresh-tags">
4171 <screen>+filter{refresh-tags} # Kill automatic refresh tags if refresh time is larger than 9 seconds.</screen>
4173 <anchor id="filter-unsolicited-popups">
4175 <screen>+filter{unsolicited-popups} # Disable only unsolicited pop-up windows.</screen>
4177 <anchor id="filter-all-popups">
4179 <screen>+filter{all-popups} # Kill all popups in JavaScript and HTML.</screen>
4181 <anchor id="filter-img-reorder">
4183 <screen>+filter{img-reorder} # Reorder attributes in <img> tags to make the banners-by-* filters more effective.</screen>
4185 <anchor id="filter-banners-by-size">
4187 <screen>+filter{banners-by-size} # Kill banners by size.</screen>
4189 <anchor id="filter-banners-by-link">
4191 <screen>+filter{banners-by-link} # Kill banners by their links to known clicktrackers.</screen>
4193 <anchor id="filter-webbugs">
4195 <screen>+filter{webbugs} # Squish WebBugs (1x1 invisible GIFs used for user tracking).</screen>
4197 <anchor id="filter-tiny-textforms">
4199 <screen>+filter{tiny-textforms} # Extend those tiny textareas up to 40x80 and kill the hard wrap.</screen>
4201 <anchor id="filter-jumping-windows">
4203 <screen>+filter{jumping-windows} # Prevent windows from resizing and moving themselves.</screen>
4205 <anchor id="filter-frameset-borders">
4207 <screen>+filter{frameset-borders} # Give frames a border and make them resizable.</screen>
4209 <anchor id="filter-iframes">
4211 <screen>+filter{iframes} # Removes all detected iframes. Should only be enabled for individual sites.</screen>
4213 <anchor id="filter-demoronizer">
4215 <screen>+filter{demoronizer} # Fix MS's non-standard use of standard charsets.</screen>
4217 <anchor id="filter-shockwave-flash">
4219 <screen>+filter{shockwave-flash} # Kill embedded Shockwave Flash objects.</screen>
4221 <anchor id="filter-quicktime-kioskmode">
4223 <screen>+filter{quicktime-kioskmode} # Make Quicktime movies saveable.</screen>
4225 <anchor id="filter-fun">
4227 <screen>+filter{fun} # Text replacements for subversive browsing fun!</screen>
4229 <anchor id="filter-crude-parental">
4231 <screen>+filter{crude-parental} # Crude parental filtering. Note that this filter doesn't work reliably.</screen>
4233 <anchor id="filter-ie-exploits">
4235 <screen>+filter{ie-exploits} # Disable some known Internet Explorer bug exploits.</screen>
4237 <anchor id="filter-site-specifics">
4239 <screen>+filter{site-specifics} # Cure for site-specific problems. Don't apply generally!</screen>
4241 <anchor id="filter-no-ping">
4243 <screen>+filter{no-ping} # Removes non-standard ping attributes in <a> and <area> tags.</screen>
4245 <anchor id="filter-google">
4247 <screen>+filter{google} # CSS-based block for Google text ads. Also removes a width limitation and the toolbar advertisement.</screen>
4249 <anchor id="filter-yahoo">
4251 <screen>+filter{yahoo} # CSS-based block for Yahoo text ads. Also removes a width limitation.</screen>
4253 <anchor id="filter-msn">
4255 <screen>+filter{msn} # CSS-based block for MSN text ads. Also removes tracking URLs and a width limitation.</screen>
4257 <anchor id="filter-blogspot">
4259 <screen>+filter{blogspot} # Cleans up some Blogspot blogs. Read the fine print before using this.</screen>
4266 <!-- ~~~~~ New section ~~~~~ -->
4267 <sect3 renderas="sect4" id="force-text-mode">
4268 <title>force-text-mode</title>
4274 <term>Typical use:</term>
4276 <para>Force <application>Privoxy</application> to treat a document as if it was in some kind of <emphasis>text</emphasis> format. </para>
4281 <term>Effect:</term>
4284 Declares a document as text, even if the <quote>Content-Type:</quote> isn't detected as such.
4291 <!-- Boolean, Parameterized, Multi-value -->
4293 <para>Boolean.</para>
4298 <term>Parameter:</term>
4310 As explained <literal><link linkend="filter">above</link></literal>,
4311 <application>Privoxy</application> tries to only filter files that are
4312 in some kind of text format. The same restrictions apply to
4313 <literal><link linkend="content-type-overwrite">content-type-overwrite</link></literal>.
4314 <literal>force-text-mode</literal> declares a document as text,
4315 without looking at the <quote>Content-Type:</quote> first.
4319 Think twice before activating this action. Filtering binary data
4320 with regular expressions can cause file damage.
4327 <term>Example usage:</term>
4338 <!-- ~~~~~ New section ~~~~~ -->
4339 <sect3 renderas="sect4" id="forward-override">
4340 <title>forward-override</title>
4346 <term>Typical use:</term>
4348 <para>Change the forwarding settings based on User-Agent or request origin</para>
4353 <term>Effect:</term>
4356 Overrules the forward directives in the configuration file.
4363 <!-- Boolean, Parameterized, Multi-value -->
4365 <para>Parameterized.</para>
4370 <term>Parameter:</term>
4374 <para><quote>forward .</quote> to use a direct connection without any additional proxies.</para>
4378 <quote>forward 127.0.0.1:8123</quote> to use the HTTP proxy listening at 127.0.0.1 port 8123.
4383 <quote>forward-socks4a 127.0.0.1:9050 .</quote> to use the socks4a proxy listening at
4384 127.0.0.1 port 9050. Replace <quote>forward-socks4a</quote> with <quote>forward-socks4</quote>
4385 to use a socks4 connection (with local DNS resolution) instead, use <quote>forward-socks5</quote>
4386 for socks5 connections (with remote DNS resolution).
4391 <quote>forward-socks4a 127.0.0.1:9050 proxy.example.org:8000</quote> to use the socks4a proxy
4392 listening at 127.0.0.1 port 9050 to reach the HTTP proxy listening at proxy.example.org port 8000.
4393 Replace <quote>forward-socks4a</quote> with <quote>forward-socks4</quote> to use a socks4 connection
4394 (with local DNS resolution) instead, use <quote>forward-socks5</quote>
4395 for socks5 connections (with remote DNS resolution).
4400 <quote>forward-webserver 127.0.0.1:80</quote> to use the HTTP
4401 server listening at 127.0.0.1 port 80 without adjusting the
4405 This makes it more convenient to use Privoxy to make
4406 existing websites available as onion services as well.
4409 Many websites serve content with hardcoded URLs and
4410 can't be easily adjusted to change the domain based
4411 on the one used by the client.
4414 Putting Privoxy between Tor and the webserver (or an stunnel
4415 that forwards to the webserver) allows to rewrite headers and
4416 content to make client and server happy at the same time.
4419 Using Privoxy for webservers that are only reachable through
4420 onion addresses and whose location is supposed to be secret
4421 is not recommended and should not be necessary anyway.
4432 This action takes parameters similar to the
4433 <link linkend="forwarding">forward</link> directives in the configuration
4434 file, but without the URL pattern. It can be used as replacement, but normally it's only
4435 used in cases where matching based on the request URL isn't sufficient.
4439 Please read the description for the <link linkend="forwarding">forward</link> directives before
4440 using this action. Forwarding to the wrong people will reduce your privacy and increase the
4441 chances of man-in-the-middle attacks.
4444 If the ports are missing or invalid, default values will be used. This might change
4445 in the future and you shouldn't rely on it. Otherwise incorrect syntax causes Privoxy
4446 to exit. Due to design limitations, invalid parameter syntax isn't detected until the
4447 action is used the first time.
4450 Use the <ulink url="http://config.privoxy.org/show-url-info">show-url-info CGI page</ulink>
4451 to verify that your forward settings do what you thought the do.
4458 <term>Example usage:</term>
4461 # Use an ssh tunnel for requests previously tagged as
4462 # <quote>User-Agent: fetch libfetch/2.0</quote> and make sure
4463 # resuming downloads continues to work.
4465 # This way you can continue to use Tor for your normal browsing,
4466 # without overloading the Tor network with your FreeBSD ports updates
4467 # or downloads of bigger files like ISOs.
4469 # Note that HTTP headers are easy to fake and therefore their
4470 # values are as (un)trustworthy as your clients and users.
4471 {+forward-override{forward-socks5 10.0.0.2:2222 .} \
4472 -hide-if-modified-since \
4473 -overwrite-last-modified \
4475 TAG:^User-Agent: fetch libfetch/2\.0$
4483 <!-- ~~~~~ New section ~~~~~ -->
4484 <sect3 renderas="sect4" id="handle-as-empty-document">
4485 <title>handle-as-empty-document</title>
4491 <term>Typical use:</term>
4493 <para>Mark URLs that should be replaced by empty documents <emphasis>if they get blocked</emphasis></para>
4498 <term>Effect:</term>
4501 This action alone doesn't do anything noticeable. It just marks URLs.
4502 If the <literal><link linkend="block">block</link></literal> action <emphasis>also applies</emphasis>,
4503 the presence or absence of this mark decides whether an HTML <quote>BLOCKED</quote>
4504 page, or an empty document will be sent to the client as a substitute for the blocked content.
4505 The <emphasis>empty</emphasis> document isn't literally empty, but actually contains a single space.
4512 <!-- Boolean, Parameterized, Multi-value -->
4514 <para>Boolean.</para>
4519 <term>Parameter:</term>
4531 Some browsers complain about syntax errors if JavaScript documents
4532 are blocked with <application>Privoxy's</application>
4533 default HTML page; this option can be used to silence them.
4534 And of course this action can also be used to eliminate the &my-app;
4535 BLOCKED message in frames.
4538 The content type for the empty document can be specified with
4539 <literal><link linkend="content-type-overwrite">content-type-overwrite{}</link></literal>,
4540 but usually this isn't necessary.
4546 <term>Example usage:</term>
4548 <screen># Block all documents on example.org that end with ".js",
4549 # but send an empty document instead of the usual HTML message.
4550 {+block{Blocked JavaScript} +handle-as-empty-document}
4559 <!-- ~~~~~ New section ~~~~~ -->
4560 <sect3 renderas="sect4" id="handle-as-image">
4561 <title>handle-as-image</title>
4565 <term>Typical use:</term>
4567 <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>
4572 <term>Effect:</term>
4575 This action alone doesn't do anything noticeable. It just marks URLs as images.
4576 If the <literal><link linkend="block">block</link></literal> action <emphasis>also applies</emphasis>,
4577 the presence or absence of this mark decides whether an HTML <quote>blocked</quote>
4578 page, or a replacement image (as determined by the <literal><link
4579 linkend="set-image-blocker">set-image-blocker</link></literal> action) will be sent to the
4580 client as a substitute for the blocked content.
4587 <!-- Boolean, Parameterized, Multi-value -->
4589 <para>Boolean.</para>
4594 <term>Parameter:</term>
4606 The below generic example section is actually part of <filename>default.action</filename>.
4607 It marks all URLs with well-known image file name extensions as images and should
4611 Users will probably only want to use the handle-as-image action in conjunction with
4612 <literal><link linkend="block">block</link></literal>, to block sources of banners, whose URLs don't
4613 reflect the file type, like in the second example section.
4616 Note that you cannot treat HTML pages as images in most cases. For instance, (in-line) ad
4617 frames require an HTML page to be sent, or they won't display properly.
4618 Forcing <literal>handle-as-image</literal> in this situation will not replace the
4619 ad frame with an image, but lead to error messages.
4625 <term>Example usage (sections):</term>
4627 <screen># Generic image extensions:
4630 /.*\.(gif|jpg|jpeg|png|bmp|ico)$
4632 # These don't look like images, but they're banners and should be
4633 # blocked as images:
4635 {+block{Nasty banners.} +handle-as-image}
4636 nasty-banner-server.example.com/junk.cgi\?output=trash
4644 <!-- ~~~~~ New section ~~~~~ -->
4645 <sect3 renderas="sect4" id="hide-accept-language">
4646 <title>hide-accept-language</title>
4652 <term>Typical use:</term>
4654 <para>Pretend to use different language settings.</para>
4659 <term>Effect:</term>
4662 Deletes or replaces the <quote>Accept-Language:</quote> HTTP header in client requests.
4669 <!-- Boolean, Parameterized, Multi-value -->
4671 <para>Parameterized.</para>
4676 <term>Parameter:</term>
4679 Keyword: <quote>block</quote>, or any user defined value.
4688 Faking the browser's language settings can be useful to make a
4689 foreign User-Agent set with
4690 <literal><link linkend="hide-user-agent">hide-user-agent</link></literal>
4694 However some sites with content in different languages check the
4695 <quote>Accept-Language:</quote> to decide which one to take by default.
4696 Sometimes it isn't possible to later switch to another language without
4697 changing the <quote>Accept-Language:</quote> header first.
4700 Therefore it's a good idea to either only change the
4701 <quote>Accept-Language:</quote> header to languages you understand,
4702 or to languages that aren't wide spread.
4705 Before setting the <quote>Accept-Language:</quote> header
4706 to a rare language, you should consider that it helps to
4707 make your requests unique and thus easier to trace.
4708 If you don't plan to change this header frequently,
4709 you should stick to a common language.
4715 <term>Example usage (section):</term>
4717 <screen># Pretend to use Canadian language settings.
4718 {+hide-accept-language{en-ca} \
4719 +hide-user-agent{Mozilla/5.0 (X11; U; OpenBSD i386; en-CA; rv:1.8.0.4) Gecko/20060628 Firefox/1.5.0.4} \
4729 <!-- ~~~~~ New section ~~~~~ -->
4730 <sect3 renderas="sect4" id="hide-content-disposition">
4731 <title>hide-content-disposition</title>
4737 <term>Typical use:</term>
4739 <para>Prevent download menus for content you prefer to view inside the browser.</para>
4744 <term>Effect:</term>
4747 Deletes or replaces the <quote>Content-Disposition:</quote> HTTP header set by some servers.
4754 <!-- Boolean, Parameterized, Multi-value -->
4756 <para>Parameterized.</para>
4761 <term>Parameter:</term>
4764 Keyword: <quote>block</quote>, or any user defined value.
4773 Some servers set the <quote>Content-Disposition:</quote> HTTP header for
4774 documents they assume you want to save locally before viewing them.
4775 The <quote>Content-Disposition:</quote> header contains the file name
4776 the browser is supposed to use by default.
4779 In most browsers that understand this header, it makes it impossible to
4780 <emphasis>just view</emphasis> the document, without downloading it first,
4781 even if it's just a simple text file or an image.
4784 Removing the <quote>Content-Disposition:</quote> header helps
4785 to prevent this annoyance, but some browsers additionally check the
4786 <quote>Content-Type:</quote> header, before they decide if they can
4787 display a document without saving it first. In these cases, you have
4788 to change this header as well, before the browser stops displaying
4792 It is also possible to change the server's file name suggestion
4793 to another one, but in most cases it isn't worth the time to set
4797 This action will probably be removed in the future,
4798 use server-header filters instead.
4804 <term>Example usage:</term>
4806 <screen># Disarm the download link in Sourceforge's patch tracker
4808 +content-type-overwrite{text/plain}\
4809 +hide-content-disposition{block} }
4810 .sourceforge.net/tracker/download\.php</screen>
4817 <!-- ~~~~~ New section ~~~~~ -->
4818 <sect3 renderas="sect4" id="hide-if-modified-since">
4819 <title>hide-if-modified-since</title>
4825 <term>Typical use:</term>
4827 <para>Prevent yet another way to track the user's steps between sessions.</para>
4832 <term>Effect:</term>
4835 Deletes the <quote>If-Modified-Since:</quote> HTTP client header or modifies its value.
4842 <!-- Boolean, Parameterized, Multi-value -->
4844 <para>Parameterized.</para>
4849 <term>Parameter:</term>
4852 Keyword: <quote>block</quote>, or a user defined value that specifies a range of hours.
4861 Removing this header is useful for filter testing, where you want to force a real
4862 reload instead of getting status code <quote>304</quote>, which would cause the
4863 browser to use a cached copy of the page.
4866 Instead of removing the header, <literal>hide-if-modified-since</literal> can
4867 also add or subtract a random amount of time to/from the header's value.
4868 You specify a range of minutes where the random factor should be chosen from and
4869 <application>Privoxy</application> does the rest. A negative value means
4870 subtracting, a positive value adding.
4873 Randomizing the value of the <quote>If-Modified-Since:</quote> makes
4874 it less likely that the server can use the time as a cookie replacement,
4875 but you will run into caching problems if the random range is too high.
4878 It is a good idea to only use a small negative value and let
4879 <literal><link linkend="overwrite-last-modified">overwrite-last-modified</link></literal>
4880 handle the greater changes.
4883 It is also recommended to use this action together with
4884 <literal><link linkend="crunch-if-none-match">crunch-if-none-match</link></literal>,
4885 otherwise it's more or less pointless.
4891 <term>Example usage (section):</term>
4893 <screen># Let the browser revalidate but make tracking based on the time less likely.
4894 {+hide-if-modified-since{-60} \
4895 +overwrite-last-modified{randomize} \
4896 +crunch-if-none-match}
4904 <!-- ~~~~~ New section ~~~~~ -->
4905 <sect3 renderas="sect4" id="hide-from-header">
4906 <title>hide-from-header</title>
4910 <term>Typical use:</term>
4912 <para>Keep your (old and ill) browser from telling web servers your email address</para>
4917 <term>Effect:</term>
4920 Deletes any existing <quote>From:</quote> HTTP header, or replaces it with the
4928 <!-- Boolean, Parameterized, Multi-value -->
4930 <para>Parameterized.</para>
4935 <term>Parameter:</term>
4938 Keyword: <quote>block</quote>, or any user defined value.
4947 The keyword <quote>block</quote> will completely remove the header
4948 (not to be confused with the <literal><link linkend="block">block</link></literal>
4952 Alternately, you can specify any value you prefer to be sent to the web
4953 server. If you do, it is a matter of fairness not to use any address that
4954 is actually used by a real person.
4957 This action is rarely needed, as modern web browsers don't send
4958 <quote>From:</quote> headers anymore.
4964 <term>Example usage:</term>
4966 <screen>+hide-from-header{block}</screen>
4968 <screen>+hide-from-header{spam-me-senseless@sittingduck.example.com}</screen>
4975 <!-- ~~~~~ New section ~~~~~ -->
4976 <sect3 renderas="sect4" id="hide-referrer">
4977 <title>hide-referrer</title>
4978 <anchor id="hide-referer">
4981 <term>Typical use:</term>
4983 <para>Conceal which link you followed to get to a particular site</para>
4988 <term>Effect:</term>
4991 Deletes the <quote>Referer:</quote> (sic) HTTP header from the client request,
4992 or replaces it with a forged one.
4999 <!-- Boolean, Parameterized, Multi-value -->
5001 <para>Parameterized.</para>
5006 <term>Parameter:</term>
5010 <para><quote>conditional-block</quote> to delete the header completely if the host has changed.</para>
5013 <para><quote>conditional-forge</quote> to forge the header if the host has changed.</para>
5016 <para><quote>block</quote> to delete the header unconditionally.</para>
5019 <para><quote>forge</quote> to pretend to be coming from the homepage of the server we are talking to.</para>
5022 <para>Any other string to set a user defined referrer.</para>
5032 <literal>conditional-block</literal> is the only parameter,
5033 that isn't easily detected in the server's log file. If it blocks the
5034 referrer, the request will look like the visitor used a bookmark or
5035 typed in the address directly.
5038 Leaving the referrer unmodified for requests on the same host
5039 allows the server owner to see the visitor's <quote>click path</quote>,
5040 but in most cases she could also get that information by comparing
5041 other parts of the log file: for example the User-Agent if it isn't
5042 a very common one, or the user's IP address if it doesn't change between
5046 Always blocking the referrer, or using a custom one, can lead to
5047 failures on servers that check the referrer before they answer any
5048 requests, in an attempt to prevent their content from being
5049 embedded or linked to elsewhere.
5052 Both <literal>conditional-block</literal> and <literal>forge</literal>
5053 will work with referrer checks, as long as content and valid referring page
5054 are on the same host. Most of the time that's the case.
5057 <literal>hide-referer</literal> is an alternate spelling of
5058 <literal>hide-referrer</literal> and the two can be can be freely
5059 substituted with each other. (<quote>referrer</quote> is the
5060 correct English spelling, however the HTTP specification has a bug - it
5061 requires it to be spelled as <quote>referer</quote>.)
5067 <term>Example usage:</term>
5069 <screen>+hide-referrer{forge}</screen>
5071 <screen>+hide-referrer{http://www.yahoo.com/}</screen>
5078 <!-- ~~~~~ New section ~~~~~ -->
5079 <sect3 renderas="sect4" id="hide-user-agent">
5080 <title>hide-user-agent</title>
5084 <term>Typical use:</term>
5086 <para>Try to conceal your type of browser and client operating system</para>
5091 <term>Effect:</term>
5094 Replaces the value of the <quote>User-Agent:</quote> HTTP header
5095 in client requests with the specified value.
5102 <!-- Boolean, Parameterized, Multi-value -->
5104 <para>Parameterized.</para>
5109 <term>Parameter:</term>
5112 Any user-defined string.
5122 This can lead to problems on web sites that depend on looking at this header in
5123 order to customize their content for different browsers (which, by the
5124 way, is <emphasis>NOT</emphasis> the right thing to do: good web sites
5125 work browser-independently).
5129 Using this action in multi-user setups or wherever different types of
5130 browsers will access the same <application>Privoxy</application> is
5131 <emphasis>not recommended</emphasis>. In single-user, single-browser
5132 setups, you might use it to delete your OS version information from
5133 the headers, because it is an invitation to exploit known bugs for your
5134 OS. It is also occasionally useful to forge this in order to access
5135 sites that won't let you in otherwise (though there may be a good
5136 reason in some cases).
5139 More information on known user-agent strings can be found at
5140 <ulink url="http://www.user-agents.org/">http://www.user-agents.org/</ulink>
5142 <ulink url="http://en.wikipedia.org/wiki/User_agent">http://en.wikipedia.org/wiki/User_agent</ulink>.
5148 <term>Example usage:</term>
5150 <screen>+hide-user-agent{Netscape 6.1 (X11; I; Linux 2.4.18 i686)}</screen>
5157 <!-- ~~~~~ New section ~~~~~ -->
5158 <sect3 renderas="sect4" id="https-inspection">
5159 <title>https-inspection</title>
5163 <term>Typical use:</term>
5165 <para>Filter encrypted requests and responses</para>
5170 <term>Effect:</term>
5173 Encrypted requests are decrypted, filtered and forwarded encrypted.
5180 <!-- boolean, parameterized, Multi-value -->
5182 <para>Boolean.</para>
5187 <term>Parameter:</term>
5199 This action allows &my-app; to filter encrypted requests and responses.
5200 For this to work &my-app; has to generate a certificate and send it
5201 to the client which has to accept it.
5204 Before this works the directives in the
5205 <literal><ulink url="config.html#TLS">TLS section</ulink></literal>
5206 of the config file have to be configured.
5209 Note that the action has to be enabled based on the CONNECT
5210 request which doesn't contain a path. Enabling it based on
5211 a pattern with path doesn't work as the path is only seen
5212 by &my-app; if the action is already enabled.
5218 <term>Example usage (section):</term>
5220 <screen>{+https-inspection}
5221 www.example.com</screen>
5229 <!-- ~~~~~ New section ~~~~~ -->
5230 <sect3 renderas="sect4" id="ignore-certificate-errors">
5231 <title>ignore-certificate-errors</title>
5235 <term>Typical use:</term>
5237 <para>Filter encrypted requests and responses without verifying the certificate</para>
5242 <term>Effect:</term>
5245 Encrypted requests are forwarded to sites without verifying the certificate.
5252 <!-- Boolean, Parameterized, Multi-value -->
5254 <para>Boolean.</para>
5259 <term>Parameter:</term>
5272 <link linkend="HTTPS-INSPECTION"><quote>+https-inspection</quote></link>
5273 action is used &my-app; by default verifies that the remote site uses a valid
5277 If the certificate can't be validated by &my-app; the connection is aborted.
5280 This action disables the certificate check so requests to sites
5281 with certificates that can't be validated are allowed.
5284 Note that enabling this action allows Man-in-the-middle attacks.
5290 <term>Example usage:</term>
5293 {+ignore-certificate-errors}
5302 <!-- ~~~~~ New section ~~~~~ -->
5303 <sect3 renderas="sect4" id="limit-connect">
5304 <title>limit-connect</title>
5308 <term>Typical use:</term>
5310 <para>Prevent abuse of <application>Privoxy</application> as a TCP proxy relay or disable SSL for untrusted sites</para>
5315 <term>Effect:</term>
5318 Specifies to which ports HTTP CONNECT requests are allowable.
5325 <!-- Boolean, Parameterized, Multi-value -->
5327 <para>Parameterized.</para>
5332 <term>Parameter:</term>
5335 A comma-separated list of ports or port ranges (the latter using dashes, with the minimum
5336 defaulting to 0 and the maximum to 65K).
5345 By default, i.e. if no <literal>limit-connect</literal> action applies,
5346 <application>Privoxy</application> allows HTTP CONNECT requests to all
5347 ports. Use <literal>limit-connect</literal> if fine-grained control
5348 is desired for some or all destinations.
5351 The CONNECT methods exists in HTTP to allow access to secure websites
5352 (<quote>https://</quote> URLs) through proxies. It works very simply:
5353 the proxy connects to the server on the specified port, and then
5354 short-circuits its connections to the client and to the remote server.
5355 This means CONNECT-enabled proxies can be used as TCP relays very easily.
5358 <application>Privoxy</application> relays HTTPS traffic without seeing
5359 the decoded content. Websites can leverage this limitation to circumvent &my-app;'s
5360 filters. By specifying an invalid port range you can disable HTTPS entirely.
5366 <term>Example usages:</term>
5368 <!-- I had trouble getting the spacing to look right in my browser -->
5369 <!-- I probably have the wrong font setup, bollocks. -->
5370 <!-- Apparently the emphasis tag uses a proportional font no matter what -->
5371 <screen>+limit-connect{443} # Port 443 is OK.
5372 +limit-connect{80,443} # Ports 80 and 443 are OK.
5373 +limit-connect{-3, 7, 20-100, 500-} # Ports less than 3, 7, 20 to 100 and above 500 are OK.
5374 +limit-connect{-} # All ports are OK
5375 +limit-connect{,} # No HTTPS/SSL traffic is allowed</screen>
5382 <!-- ~~~~~ New section ~~~~~ -->
5383 <sect3 renderas="sect4" id="limit-cookie-lifetime">
5384 <title>limit-cookie-lifetime</title>
5388 <term>Typical use:</term>
5390 <para>Limit the lifetime of HTTP cookies to a couple of minutes or hours.</para>
5395 <term>Effect:</term>
5398 Overwrites the expires field in Set-Cookie server headers if it's above the specified limit.
5405 <!-- Boolean, Parameterized, Multi-value -->
5407 <para>Parameterized.</para>
5412 <term>Parameter:</term>
5415 The lifetime limit in minutes, or 0.
5424 This action reduces the lifetime of HTTP cookies coming from the
5425 server to the specified number of minutes, starting from the time
5426 the cookie passes Privoxy.
5429 Cookies with a lifetime below the limit are not modified.
5430 The lifetime of session cookies is set to the specified limit.
5433 The effect of this action depends on the server.
5436 In case of servers which refresh their cookies with each response
5437 (or at least frequently), the lifetime limit set by this action
5439 Thus, a session associated with the cookie continues to work with
5440 this action enabled, as long as a new request is made before the
5441 last limit set is reached.
5444 However, some servers send their cookies once, with a lifetime of several
5445 years (the year 2037 is a popular choice), and do not refresh them
5446 until a certain event in the future, for example the user logging out.
5447 In this case this action may limit the absolute lifetime of the session,
5448 even if requests are made frequently.
5451 If the parameter is <quote>0</quote>, this action behaves like
5452 <literal><link linkend="session-cookies-only">session-cookies-only</link></literal>.
5458 <term>Example usages:</term>
5460 <screen>+limit-cookie-lifetime{60}</screen>
5466 <!-- ~~~~~ New section ~~~~~ -->
5467 <sect3 renderas="sect4" id="prevent-compression">
5468 <title>prevent-compression</title>
5472 <term>Typical use:</term>
5475 Ensure that servers send the content uncompressed, so it can be
5476 passed through <literal><link linkend="filter">filter</link></literal>s.
5482 <term>Effect:</term>
5485 Removes the Accept-Encoding header which can be used to ask for compressed transfer.
5492 <!-- Boolean, Parameterized, Multi-value -->
5494 <para>Boolean.</para>
5499 <term>Parameter:</term>
5511 More and more websites send their content compressed by default, which
5512 is generally a good idea and saves bandwidth. But the <literal><link
5513 linkend="filter">filter</link></literal> and
5514 <literal><link linkend="deanimate-gifs">deanimate-gifs</link></literal>
5515 actions need access to the uncompressed data.
5518 When compiled with zlib support (available since &my-app; 3.0.7), content that should be
5519 filtered is decompressed on-the-fly and you don't have to worry about this action.
5520 If you are using an older &my-app; version, or one that hasn't been compiled with zlib
5521 support, this action can be used to convince the server to send the content uncompressed.
5524 Most text-based instances compress very well, the size is seldom decreased by less than 50%,
5525 for markup-heavy instances like news feeds saving more than 90% of the original size isn't
5529 Not using compression will therefore slow down the transfer, and you should only
5530 enable this action if you really need it. As of &my-app; 3.0.7 it's disabled in all
5531 predefined action settings.
5534 Note that some (rare) ill-configured sites don't handle requests for uncompressed
5535 documents correctly. Broken PHP applications tend to send an empty document body,
5536 some IIS versions only send the beginning of the content and some content delivery
5537 networks let the connection time out.
5538 If you enable <literal>prevent-compression</literal> per default, you might
5539 want to add exceptions for those sites. See the example for how to do that.
5545 <term>Example usage (sections):</term>
5548 # Selectively turn off compression, and enable a filter
5550 { +filter{tiny-textforms} +prevent-compression }
5551 # Match only these sites
5556 # Or instead, we could set a universal default:
5558 { +prevent-compression }
5561 # Then maybe make exceptions for broken sites:
5563 { -prevent-compression }
5564 .compusa.com/</screen>
5572 <!-- ~~~~~ New section ~~~~~ -->
5573 <sect3 renderas="sect4" id="overwrite-last-modified">
5574 <title>overwrite-last-modified</title>
5580 <term>Typical use:</term>
5582 <para>Prevent yet another way to track the user's steps between sessions.</para>
5587 <term>Effect:</term>
5590 Deletes the <quote>Last-Modified:</quote> HTTP server header or modifies its value.
5597 <!-- Boolean, Parameterized, Multi-value -->
5599 <para>Parameterized.</para>
5604 <term>Parameter:</term>
5607 One of the keywords: <quote>block</quote>, <quote>reset-to-request-time</quote>
5608 and <quote>randomize</quote>
5617 Removing the <quote>Last-Modified:</quote> header is useful for filter
5618 testing, where you want to force a real reload instead of getting status
5619 code <quote>304</quote>, which would cause the browser to reuse the old
5620 version of the page.
5623 The <quote>randomize</quote> option overwrites the value of the
5624 <quote>Last-Modified:</quote> header with a randomly chosen time
5625 between the original value and the current time. In theory the server
5626 could send each document with a different <quote>Last-Modified:</quote>
5627 header to track visits without using cookies. <quote>Randomize</quote>
5628 makes it impossible and the browser can still revalidate cached documents.
5631 <quote>reset-to-request-time</quote> overwrites the value of the
5632 <quote>Last-Modified:</quote> header with the current time. You could use
5633 this option together with
5634 <literal><link linkend="hide-if-modified-since">hide-if-modified-since</link></literal>
5635 to further customize your random range.
5638 The preferred parameter here is <quote>randomize</quote>. It is safe
5639 to use, as long as the time settings are more or less correct.
5640 If the server sets the <quote>Last-Modified:</quote> header to the time
5641 of the request, the random range becomes zero and the value stays the same.
5642 Therefore you should later randomize it a second time with
5643 <literal><link linkend="hide-if-modified-since">hided-if-modified-since</link></literal>,
5647 It is also recommended to use this action together with
5648 <literal><link linkend="crunch-if-none-match">crunch-if-none-match</link></literal>.
5654 <term>Example usage:</term>
5656 <screen># Let the browser revalidate without being tracked across sessions
5657 { +hide-if-modified-since{-60} \
5658 +overwrite-last-modified{randomize} \
5659 +crunch-if-none-match}
5667 <!-- ~~~~~ New section ~~~~~ -->
5668 <sect3 renderas="sect4" id="redirect">
5669 <title>redirect</title>
5675 <term>Typical use:</term>
5678 Redirect requests to other sites.
5684 <term>Effect:</term>
5687 Convinces the browser that the requested document has been moved
5688 to another location and the browser should get it from there.
5695 <!-- Boolean, Parameterized, Multi-value -->
5697 <para>Parameterized</para>
5702 <term>Parameter:</term>
5705 An absolute URL or a single pcrs command.
5714 Requests to which this action applies are answered with a
5715 HTTP redirect to URLs of your choosing. The new URL is
5716 either provided as parameter, or derived by applying a
5717 single pcrs command to the original URL.
5720 The syntax for pcrs commands is documented in the
5721 <link linkend="filter-file">filter file</link> section.
5724 Requests can't be blocked and redirected at the same time,
5725 applying this action together with
5726 <literal><link linkend="block">block</link></literal>
5727 is a configuration error. Currently the request is blocked
5728 and an error message logged, the behavior may change in the
5729 future and result in Privoxy rejecting the action file.
5732 This action can be combined with
5733 <literal><link linkend="fast-redirects">fast-redirects{check-decoded-url}</link></literal>
5734 to redirect to a decoded version of a rewritten URL.
5737 Use this action carefully, make sure not to create redirection loops
5738 and be aware that using your own redirects might make it
5739 possible to fingerprint your requests.
5742 In case of problems with your redirects, or simply to watch
5743 them working, enable <link linkend="DEBUG">debug 128</link>.
5749 <term>Example usages:</term>
5751 <screen># Replace example.com's style sheet with another one
5752 { +redirect{http://localhost/css-replacements/example.com.css} }
5753 example.com/stylesheet\.css
5755 # Create a short, easy to remember nickname for a favorite site
5756 # (relies on the browser to accept and forward invalid URLs to &my-app;)
5757 { +redirect{https://www.privoxy.org/user-manual/actions-file.html} }
5760 # Always use the expanded view for Undeadly.org articles
5761 # (Note the $ at the end of the URL pattern to make sure
5762 # the request for the rewritten URL isn't redirected as well)
5763 {+redirect{s@$@&mode=expanded@}}
5764 undeadly.org/cgi\?action=article&sid=\d*$
5766 # Redirect Google search requests to MSN
5767 {+redirect{s@^http://[^/]*/search\?q=([^&]*).*@http://search.msn.com/results.aspx?q=$1@}}
5770 # Redirect MSN search requests to Yahoo
5771 {+redirect{s@^http://[^/]*/results\.aspx\?q=([^&]*).*@http://search.yahoo.com/search?p=$1@}}
5772 search.msn.com//results\.aspx\?q=
5774 # Redirect http://example.com/&bla=fasel&toChange=foo (and any other value but "bar")
5775 # to http://example.com/&bla=fasel&toChange=bar
5777 # The URL pattern makes sure that the following request isn't redirected again.
5778 {+redirect{s@toChange=[^&]+@toChange=bar@}}
5779 example.com/.*toChange=(?!bar)
5781 # Add a shortcut to look up illumos bugs
5782 {+redirect{s@^http://i([0-9]+)/.*@https://www.illumos.org/issues/$1@}}
5783 # Redirected URL = http://i4974/
5784 # Redirect Destination = https://www.illumos.org/issues/4974
5785 i[0-9][0-9][0-9][0-9]*/
5787 # Redirect remote requests for this manual
5788 # to the local version delivered by Privoxy
5789 {+redirect{s@^http://www@http://config@}}
5790 www.privoxy.org/user-manual/</screen>
5798 <!-- ~~~~~ New section ~~~~~ -->
5799 <sect3 renderas="sect4" id="server-header-filter">
5800 <title>server-header-filter</title>
5804 <term>Typical use:</term>
5807 Rewrite or remove single server headers.
5813 <term>Effect:</term>
5816 All server headers to which this action applies are filtered on-the-fly
5817 through the specified regular expression based substitutions.
5824 <!-- boolean, parameterized, Multi-value -->
5826 <para>Multi-value.</para>
5831 <term>Parameter:</term>
5834 The name of a server-header filter, as defined in one of the
5835 <link linkend="filter-file">filter files</link>.
5844 Server-header filters are applied to each header on its own, not to
5845 all at once. This makes it easier to diagnose problems, but on the downside
5846 you can't write filters that only change header x if header y's value is z.
5847 You can do that by using tags though.
5850 Server-header filters are executed after the other header actions have finished
5851 and use their output as input.
5854 Please refer to the <link linkend="filter-file">filter file chapter</link>
5855 to learn which server-header filters are available by default, and how to
5862 <term>Example usage (section):</term>
5865 {+server-header-filter{html-to-xml}}
5866 example.org/xml-instance-that-is-delivered-as-html
5868 {+server-header-filter{xml-to-html}}
5869 example.org/instance-that-is-delivered-as-xml-but-is-not
5878 <!-- ~~~~~ New section ~~~~~ -->
5879 <sect3 renderas="sect4" id="server-header-tagger">
5880 <title>server-header-tagger</title>
5884 <term>Typical use:</term>
5887 Enable or disable filters based on the Content-Type header.
5893 <term>Effect:</term>
5896 Server headers to which this action applies are filtered on-the-fly through
5897 the specified regular expression based substitutions, the result is used as
5905 <!-- boolean, parameterized, Multi-value -->
5907 <para>Multi-value.</para>
5912 <term>Parameter:</term>
5915 The name of a server-header tagger, as defined in one of the
5916 <link linkend="filter-file">filter files</link>.
5925 Server-header taggers are applied to each header on its own,
5926 and as the header isn't modified, each tagger <quote>sees</quote>
5930 Server-header taggers are executed before all other header actions
5931 that modify server headers. Their tags can be used to control
5932 all of the other server-header actions, the content filters
5933 and the crunch actions (<link linkend="redirect">redirect</link>
5934 and <link linkend="block">block</link>).
5937 Obviously crunching based on tags created by server-header taggers
5938 doesn't prevent the request from showing up in the server's log file.
5945 <term>Example usage (section):</term>
5948 # Tag every request with the content type declared by the server
5949 {+server-header-tagger{content-type}}
5952 # If the response has a tag starting with 'image/' enable an external
5953 # filter that only applies to images.
5955 # Note that the filter is not available by default, it's just a
5956 # <literal><link linkend="external-filter-syntax">silly example</link></literal>.
5957 {+external-filter{rotate-image} +force-text-mode}
5967 <!-- ~~~~~ New section ~~~~~ -->
5968 <sect3 renderas="sect4" id="session-cookies-only">
5969 <title>session-cookies-only</title>
5973 <term>Typical use:</term>
5976 Allow only temporary <quote>session</quote> cookies (for the current
5977 browser session <emphasis>only</emphasis>).
5983 <term>Effect:</term>
5986 Deletes the <quote>expires</quote> field from <quote>Set-Cookie:</quote>
5987 server headers. Most browsers will not store such cookies permanently and
5988 forget them in between sessions.
5995 <!-- Boolean, Parameterized, Multi-value -->
5997 <para>Boolean.</para>
6002 <term>Parameter:</term>
6014 This is less strict than <literal><link linkend="crunch-incoming-cookies">crunch-incoming-cookies</link></literal> /
6015 <literal><link linkend="crunch-outgoing-cookies">crunch-outgoing-cookies</link></literal> and allows you to browse
6016 websites that insist or rely on setting cookies, without compromising your privacy too badly.
6019 Most browsers will not permanently store cookies that have been processed by
6020 <literal>session-cookies-only</literal> and will forget about them between sessions.
6021 This makes profiling cookies useless, but won't break sites which require cookies so
6022 that you can log in for transactions. This is generally turned on for all
6023 sites, and is the recommended setting.
6026 It makes <emphasis>no sense at all</emphasis> to use <literal>session-cookies-only</literal>
6027 together with <literal><link linkend="crunch-incoming-cookies">crunch-incoming-cookies</link></literal> or
6028 <literal><link linkend="crunch-outgoing-cookies">crunch-outgoing-cookies</link></literal>. If you do, cookies
6029 will be plainly killed.
6032 Note that it is up to the browser how it handles such cookies without an <quote>expires</quote>
6033 field. If you use an exotic browser, you might want to try it out to be sure.
6036 This setting also has no effect on cookies that may have been stored
6037 previously by the browser before starting <application>Privoxy</application>.
6038 These would have to be removed manually.
6041 <application>Privoxy</application> also uses
6042 the <link linkend="filter-content-cookies">content-cookies filter</link>
6043 to block some types of cookies. Content cookies are not effected by
6044 <literal>session-cookies-only</literal>.
6050 <term>Example usage:</term>
6052 <screen>+session-cookies-only</screen>
6059 <!-- ~~~~~ New section ~~~~~ -->
6060 <sect3 renderas="sect4" id="set-image-blocker">
6061 <title>set-image-blocker</title>
6065 <term>Typical use:</term>
6067 <para>Choose the replacement for blocked images</para>
6072 <term>Effect:</term>
6075 This action alone doesn't do anything noticeable. If <emphasis>both</emphasis>
6076 <literal><link linkend="block">block</link></literal> <emphasis>and</emphasis> <literal><link
6077 linkend="handle-as-image">handle-as-image</link></literal> <emphasis>also</emphasis>
6078 apply, i.e. if the request is to be blocked as an image,
6079 <emphasis>then</emphasis> the parameter of this action decides what will be
6080 sent as a replacement.
6087 <!-- Boolean, Parameterized, Multi-value -->
6089 <para>Parameterized.</para>
6094 <term>Parameter:</term>
6099 <quote>pattern</quote> to send a built-in checkerboard pattern image. The image is visually
6100 decent, scales very well, and makes it obvious where banners were busted.
6105 <quote>blank</quote> to send a built-in transparent image. This makes banners disappear
6106 completely, but makes it hard to detect where <application>Privoxy</application> has blocked
6107 images on a given page and complicates troubleshooting if <application>Privoxy</application>
6108 has blocked innocent images, like navigation icons.
6113 <quote><replaceable class="parameter">target-url</replaceable></quote> to
6114 send a redirect to <replaceable class="parameter">target-url</replaceable>. You can redirect
6115 to any image anywhere, even in your local filesystem via <quote>file:///</quote> URL.
6116 (But note that not all browsers support redirecting to a local file system).
6119 A good application of redirects is to use special <application>Privoxy</application>-built-in
6120 URLs, which send the built-in images, as <replaceable class="parameter">target-url</replaceable>.
6121 This has the same visual effect as specifying <quote>blank</quote> or <quote>pattern</quote> in
6122 the first place, but enables your browser to cache the replacement image, instead of requesting
6123 it over and over again.
6134 The URLs for the built-in images are <quote>http://config.privoxy.org/send-banner?type=<replaceable
6135 class="parameter">type</replaceable></quote>, where <replaceable class="parameter">type</replaceable> is
6136 either <quote>blank</quote> or <quote>pattern</quote>.
6139 There is a third (advanced) type, called <quote>auto</quote>. It is <emphasis>NOT</emphasis> to be
6140 used in <literal>set-image-blocker</literal>, but meant for use from <link linkend="filter-file">filters</link>.
6141 Auto will select the type of image that would have applied to the referring page, had it been an image.
6147 <term>Example usage:</term>
6152 <screen>+set-image-blocker{pattern}</screen>
6154 Redirect to the BSD daemon:
6156 <screen>+set-image-blocker{http://www.freebsd.org/gifs/dae_up3.gif}</screen>
6158 Redirect to the built-in pattern for better caching:
6160 <screen>+set-image-blocker{http://config.privoxy.org/send-banner?type=pattern}</screen>
6167 <!-- ~~~~~ New section ~~~~~ -->
6168 <sect3 id="summary">
6169 <title>Summary</title>
6171 Note that many of these actions have the potential to cause a page to
6172 misbehave, possibly even not to display at all. There are many ways
6173 a site designer may choose to design his site, and what HTTP header
6174 content, and other criteria, he may depend on. There is no way to have hard
6175 and fast rules for all sites. See the <link
6176 linkend="ACTIONSANAT">Appendix</link> for a brief example on troubleshooting
6182 <!-- ~~~~~ New section ~~~~~ -->
6183 <sect2 id="aliases">
6184 <title>Aliases</title>
6186 Custom <quote>actions</quote>, known to <application>Privoxy</application>
6187 as <quote>aliases</quote>, can be defined by combining other actions.
6188 These can in turn be invoked just like the built-in actions.
6189 Currently, an alias name can contain any character except space, tab,
6191 <quote>{</quote> and <quote>}</quote>, but we <emphasis>strongly
6192 recommend</emphasis> that you only use <quote>a</quote> to <quote>z</quote>,
6193 <quote>0</quote> to <quote>9</quote>, <quote>+</quote>, and <quote>-</quote>.
6194 Alias names are not case sensitive, and are not required to start with a
6195 <quote>+</quote> or <quote>-</quote> sign, since they are merely textually
6199 Aliases can be used throughout the actions file, but they <emphasis>must be
6200 defined in a special section at the top of the file!</emphasis>
6201 And there can only be one such section per actions file. Each actions file may
6202 have its own alias section, and the aliases defined in it are only visible
6206 There are two main reasons to use aliases: One is to save typing for frequently
6207 used combinations of actions, the other one is a gain in flexibility: If you
6208 decide once how you want to handle shops by defining an alias called
6209 <quote>shop</quote>, you can later change your policy on shops in
6210 <emphasis>one</emphasis> place, and your changes will take effect everywhere
6211 in the actions file where the <quote>shop</quote> alias is used. Calling aliases
6212 by their purpose also makes your actions files more readable.
6215 Currently, there is one big drawback to using aliases, though:
6216 <application>Privoxy</application>'s built-in web-based action file
6217 editor honors aliases when reading the actions files, but it expands
6218 them before writing. So the effects of your aliases are of course preserved,
6219 but the aliases themselves are lost when you edit sections that use aliases
6224 Now let's define some aliases...
6228 # Useful custom aliases we can use later.
6230 # Note the (required!) section header line and that this section
6231 # must be at the top of the actions file!
6235 # These aliases just save typing later:
6236 # (Note that some already use other aliases!)
6238 +crunch-all-cookies = +<link linkend="CRUNCH-INCOMING-COOKIES">crunch-incoming-cookies</link> +<link linkend="CRUNCH-OUTGOING-COOKIES">crunch-outgoing-cookies</link>
6239 -crunch-all-cookies = -<link linkend="CRUNCH-INCOMING-COOKIES">crunch-incoming-cookies</link> -<link linkend="CRUNCH-OUTGOING-COOKIES">crunch-outgoing-cookies</link>
6240 +block-as-image = +block{Blocked image.} +handle-as-image
6241 allow-all-cookies = -crunch-all-cookies -<link linkend="SESSION-COOKIES-ONLY">session-cookies-only</link> -<link linkend="FILTER-CONTENT-COOKIES">filter{content-cookies}</link>
6243 # These aliases define combinations of actions
6244 # that are useful for certain types of sites:
6246 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>
6248 shop = -crunch-all-cookies -<link linkend="FILTER-ALL-POPUPS">filter{all-popups}</link>
6250 # Short names for other aliases, for really lazy people ;-)
6252 c0 = +crunch-all-cookies
6253 c1 = -crunch-all-cookies</screen>
6256 ...and put them to use. These sections would appear in the lower part of an
6257 actions file and define exceptions to the default actions (as specified further
6258 up for the <quote>/</quote> pattern):
6262 # These sites are either very complex or very keen on
6263 # user data and require minimal interference to work:
6266 .office.microsoft.com
6267 .windowsupdate.microsoft.com
6268 # Gmail is really mail.google.com, not gmail.com
6272 # Allow cookies (for setting and retrieving your customer data)
6276 .worldpay.com # for quietpc.com
6279 # These shops require pop-ups:
6281 {-filter{all-popups} -filter{unsolicited-popups}}
6283 .overclockers.co.uk</screen>
6286 Aliases like <quote>shop</quote> and <quote>fragile</quote> are typically used for
6287 <quote>problem</quote> sites that require more than one action to be disabled
6288 in order to function properly.
6294 <!-- ~~~~~ New section ~~~~~ -->
6295 <sect2 id="act-examples">
6296 <title>Actions Files Tutorial</title>
6298 The above chapters have shown <link linkend="actions-file">which actions files
6299 there are and how they are organized</link>, how actions are <link
6300 linkend="actions">specified</link> and <link linkend="actions-apply">applied
6301 to URLs</link>, how <link linkend="af-patterns">patterns</link> work, and how to
6302 define and use <link linkend="aliases">aliases</link>. Now, let's look at an
6303 example <filename>match-all.action</filename>, <filename>default.action</filename>
6304 and <filename>user.action</filename> file and see how all these pieces come together:
6307 <sect3 id="match-all">
6308 <title>match-all.action</title>
6310 Remember <emphasis>all actions are disabled when matching starts</emphasis>,
6311 so we have to explicitly enable the ones we want.
6315 While the <filename>match-all.action</filename> file only contains a
6316 single section, it is probably the most important one. It has only one
6317 pattern, <quote><literal>/</literal></quote>, but this pattern
6318 <link linkend="af-patterns">matches all URLs</link>. Therefore, the set of
6319 actions used in this <quote>default</quote> section <emphasis>will
6320 be applied to all requests as a start</emphasis>. It can be partly or
6321 wholly overridden by other actions files like <filename>default.action</filename>
6322 and <filename>user.action</filename>, but it will still be largely responsible
6323 for your overall browsing experience.
6327 Again, at the start of matching, all actions are disabled, so there is
6328 no need to disable any actions here. (Remember: a <quote>+</quote>
6329 preceding the action name enables the action, a <quote>-</quote> disables!).
6330 Also note how this long line has been made more readable by splitting it into
6331 multiple lines with line continuation.
6336 +<link linkend="CHANGE-X-FORWARDED-FOR">change-x-forwarded-for{block}</link> \
6337 +<link linkend="HIDE-FROM-HEADER">hide-from-header{block}</link> \
6338 +<link linkend="SET-IMAGE-BLOCKER">set-image-blocker{pattern}</link> \
6344 The default behavior is now set.
6348 <sect3 id="default-action">
6349 <title>default.action</title>
6352 If you aren't a developer, there's no need for you to edit the
6353 <filename>default.action</filename> file. It is maintained by
6354 the &my-app; developers and if you disagree with some of the
6355 sections, you should overrule them in your <filename>user.action</filename>.
6359 Understanding the <filename>default.action</filename> file can
6360 help you with your <filename>user.action</filename>, though.
6364 The first section in this file is a special section for internal use
6365 that prevents older &my-app; versions from reading the file:
6369 ##########################################################################
6370 # Settings -- Don't change! For internal Privoxy use ONLY.
6371 ##########################################################################
6373 for-privoxy-version=3.0.11</screen>
6376 After that comes the (optional) alias section. We'll use the example
6377 section from the above <link linkend="aliases">chapter on aliases</link>,
6378 that also explains why and how aliases are used:
6382 ##########################################################################
6384 ##########################################################################
6387 # These aliases just save typing later:
6388 # (Note that some already use other aliases!)
6390 +crunch-all-cookies = +<link linkend="CRUNCH-INCOMING-COOKIES">crunch-incoming-cookies</link> +<link linkend="CRUNCH-OUTGOING-COOKIES">crunch-outgoing-cookies</link>
6391 -crunch-all-cookies = -<link linkend="CRUNCH-INCOMING-COOKIES">crunch-incoming-cookies</link> -<link linkend="CRUNCH-OUTGOING-COOKIES">crunch-outgoing-cookies</link>
6392 +block-as-image = +block{Blocked image.} +handle-as-image
6393 mercy-for-cookies = -crunch-all-cookies -<link linkend="SESSION-COOKIES-ONLY">session-cookies-only</link> -<link linkend="FILTER-CONTENT-COOKIES">filter{content-cookies}</link>
6395 # These aliases define combinations of actions
6396 # that are useful for certain types of sites:
6398 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>
6399 shop = -crunch-all-cookies -<link linkend="FILTER-ALL-POPUPS">filter{all-popups}</link></screen>
6402 The first of our specialized sections is concerned with <quote>fragile</quote>
6403 sites, i.e. sites that require minimum interference, because they are either
6404 very complex or very keen on tracking you (and have mechanisms in place that
6405 make them unusable for people who avoid being tracked). We will use
6406 our pre-defined <literal>fragile</literal> alias instead of stating the list
6407 of actions explicitly:
6411 ##########################################################################
6412 # Exceptions for sites that'll break under the default action set:
6413 ##########################################################################
6415 # "Fragile" Use a minimum set of actions for these sites (see alias above):
6418 .office.microsoft.com # surprise, surprise!
6419 .windowsupdate.microsoft.com
6420 mail.google.com</screen>
6423 Shopping sites are not as fragile, but they typically
6424 require cookies to log in, and pop-up windows for shopping
6425 carts or item details. Again, we'll use a pre-defined alias:
6433 .worldpay.com # for quietpc.com
6435 .scan.co.uk</screen>
6438 The <literal><link linkend="FAST-REDIRECTS">fast-redirects</link></literal>
6439 action, which may have been enabled in <filename>match-all.action</filename>,
6440 breaks some sites. So disable it for popular sites where we know it misbehaves:
6444 { -<link linkend="FAST-REDIRECTS">fast-redirects</link> }
6448 .altavista.com/.*(like|url|link):http
6449 .altavista.com/trans.*urltext=http
6450 .nytimes.com</screen>
6453 It is important that <application>Privoxy</application> knows which
6454 URLs belong to images, so that <emphasis>if</emphasis> they are to
6455 be blocked, a substitute image can be sent, rather than an HTML page.
6456 Contacting the remote site to find out is not an option, since it
6457 would destroy the loading time advantage of banner blocking, and it
6458 would feed the advertisers information about you. We can mark any
6459 URL as an image with the <literal><link
6460 linkend="handle-as-image">handle-as-image</link></literal> action,
6461 and marking all URLs that end in a known image file extension is a
6466 ##########################################################################
6468 ##########################################################################
6470 # Define which file types will be treated as images, in case they get
6471 # blocked further down this file:
6473 { +<link linkend="HANDLE-AS-IMAGE">handle-as-image</link> }
6474 /.*\.(gif|jpe?g|png|bmp|ico)$</screen>
6477 And then there are known banner sources. They often use scripts to
6478 generate the banners, so it won't be visible from the URL that the
6479 request is for an image. Hence we block them <emphasis>and</emphasis>
6480 mark them as images in one go, with the help of our
6481 <literal>+block-as-image</literal> alias defined above. (We could of
6482 course just as well use <literal>+<link linkend="block">block</link>
6483 +<link linkend="handle-as-image">handle-as-image</link></literal> here.)
6484 Remember that the type of the replacement image is chosen by the
6485 <literal><link linkend="set-image-blocker">set-image-blocker</link></literal>
6486 action. Since all URLs have matched the default section with its
6487 <literal>+<link linkend="set-image-blocker">set-image-blocker</link>{pattern}</literal>
6488 action before, it still applies and needn't be repeated:
6492 # Known ad generators:
6497 .ad.*.doubleclick.net
6498 .a.yimg.com/(?:(?!/i/).)*$
6499 .a[0-9].yimg.com/(?:(?!/i/).)*$
6504 One of the most important jobs of <application>Privoxy</application>
6505 is to block banners. Many of these can be <quote>blocked</quote>
6506 by the <literal><link linkend="filter">filter</link>{banners-by-size}</literal>
6507 action, which we enabled above, and which deletes the references to banner
6508 images from the pages while they are loaded, so the browser doesn't request
6509 them anymore, and hence they don't need to be blocked here. But this naturally
6510 doesn't catch all banners, and some people choose not to use filters, so we
6511 need a comprehensive list of patterns for banner URLs here, and apply the
6512 <literal><link linkend="block">block</link></literal> action to them.
6515 First comes many generic patterns, which do most of the work, by
6516 matching typical domain and path name components of banners. Then comes
6517 a list of individual patterns for specific sites, which is omitted here
6518 to keep the example short:
6522 ##########################################################################
6523 # Block these fine banners:
6524 ##########################################################################
6525 { <link linkend="BLOCK">+block{Banner ads.}</link> }
6533 /.*count(er)?\.(pl|cgi|exe|dll|asp|php[34]?)
6534 /(?:.*/)?(publicite|werbung|rekla(ma|me|am)|annonse|maino(kset|nta|s)?)/
6536 # Site-specific patterns (abbreviated):
6538 .hitbox.com</screen>
6541 It's quite remarkable how many advertisers actually call their banner
6542 servers ads.<replaceable>company</replaceable>.com, or call the directory
6543 in which the banners are stored literally <quote>banners</quote>. So the above
6544 generic patterns are surprisingly effective.
6547 But being very generic, they necessarily also catch URLs that we don't want
6548 to block. The pattern <literal>.*ads.</literal> e.g. catches
6549 <quote>nasty-<emphasis>ads</emphasis>.nasty-corp.com</quote> as intended,
6550 but also <quote>downlo<emphasis>ads</emphasis>.sourcefroge.net</quote> or
6551 <quote><emphasis>ads</emphasis>l.some-provider.net.</quote> So here come some
6552 well-known exceptions to the <literal>+<link linkend="BLOCK">block</link></literal>
6556 Note that these are exceptions to exceptions from the default! Consider the URL
6557 <quote>downloads.sourcefroge.net</quote>: Initially, all actions are deactivated,
6558 so it wouldn't get blocked. Then comes the defaults section, which matches the
6559 URL, but just deactivates the <literal><link linkend="BLOCK">block</link></literal>
6560 action once again. Then it matches <literal>.*ads.</literal>, an exception to the
6561 general non-blocking policy, and suddenly
6562 <literal><link linkend="BLOCK">+block</link></literal> applies. And now, it'll match
6563 <literal>.*loads.</literal>, where <literal><link linkend="BLOCK">-block</link></literal>
6564 applies, so (unless it matches <emphasis>again</emphasis> further down) it ends up
6565 with no <literal><link linkend="BLOCK">block</link></literal> action applying.
6569 ##########################################################################
6570 # Save some innocent victims of the above generic block patterns:
6571 ##########################################################################
6575 { -<link linkend="BLOCK">block</link> }
6576 adv[io]*. # (for advogato.org and advice.*)
6577 adsl. # (has nothing to do with ads)
6578 adobe. # (has nothing to do with ads either)
6579 ad[ud]*. # (adult.* and add.*)
6580 .edu # (universities don't host banners (yet!))
6581 .*loads. # (downloads, uploads etc)
6589 www.globalintersec.com/adv # (adv = advanced)
6590 www.ugu.com/sui/ugu/adv</screen>
6593 Filtering source code can have nasty side effects,
6594 so make an exception for our friends at sourceforge.net,
6595 and all paths with <quote>cvs</quote> in them. Note that
6596 <literal>-<link linkend="FILTER">filter</link></literal>
6597 disables <emphasis>all</emphasis> filters in one fell swoop!
6601 # Don't filter code!
6603 { -<link linkend="FILTER">filter</link> }
6608 .sourceforge.net</screen>
6611 The actual <filename>default.action</filename> is of course much more
6612 comprehensive, but we hope this example made clear how it works.
6617 <sect3 id="user-action"><title>user.action</title>
6620 So far we are painting with a broad brush by setting general policies,
6621 which would be a reasonable starting point for many people. Now,
6622 you might want to be more specific and have customized rules that
6623 are more suitable to your personal habits and preferences. These would
6624 be for narrowly defined situations like your ISP or your bank, and should
6625 be placed in <filename>user.action</filename>, which is parsed after all other
6626 actions files and hence has the last word, over-riding any previously
6627 defined actions. <filename>user.action</filename> is also a
6628 <emphasis>safe</emphasis> place for your personal settings, since
6629 <filename>default.action</filename> is actively maintained by the
6630 <application>Privoxy</application> developers and you'll probably want
6631 to install updated versions from time to time.
6635 So let's look at a few examples of things that one might typically do in
6636 <filename>user.action</filename>:
6640 <!-- brief sample user.action here -->
6643 # My user.action file. <fred@example.com></screen>
6646 As <link linkend="aliases">aliases</link> are local to the actions
6647 file that they are defined in, you can't use the ones from
6648 <filename>default.action</filename>, unless you repeat them here:
6652 # Aliases are local to the file they are defined in.
6653 # (Re-)define aliases for this file:
6657 # These aliases just save typing later, and the alias names should
6658 # be self explanatory.
6660 +crunch-all-cookies = +crunch-incoming-cookies +crunch-outgoing-cookies
6661 -crunch-all-cookies = -crunch-incoming-cookies -crunch-outgoing-cookies
6662 allow-all-cookies = -crunch-all-cookies -session-cookies-only
6663 allow-popups = -filter{all-popups}
6664 +block-as-image = +block{Blocked as image.} +handle-as-image
6665 -block-as-image = -block
6667 # These aliases define combinations of actions that are useful for
6668 # certain types of sites:
6670 fragile = -block -crunch-all-cookies -filter -fast-redirects -hide-referrer
6671 shop = -crunch-all-cookies allow-popups
6673 # Allow ads for selected useful free sites:
6675 allow-ads = -block -filter{banners-by-size} -filter{banners-by-link}
6677 # Alias for specific file types that are text, but might have conflicting
6678 # MIME types. We want the browser to force these to be text documents.
6679 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>
6682 Say you have accounts on some sites that you visit regularly, and
6683 you don't want to have to log in manually each time. So you'd like
6684 to allow persistent cookies for these sites. The
6685 <literal>allow-all-cookies</literal> alias defined above does exactly
6686 that, i.e. it disables crunching of cookies in any direction, and the
6687 processing of cookies to make them only temporary.
6691 { allow-all-cookies }
6695 .redhat.com</screen>
6698 Your bank is allergic to some filter, but you don't know which, so you disable them all:
6702 { -<link linkend="FILTER">filter</link> }
6703 .your-home-banking-site.com</screen>
6706 Some file types you may not want to filter for various reasons:
6710 # Technical documentation is likely to contain strings that might
6711 # erroneously get altered by the JavaScript-oriented filters:
6716 # And this stupid host sends streaming video with a wrong MIME type,
6717 # so that Privoxy thinks it is getting HTML and starts filtering:
6719 stupid-server.example.com/</screen>
6722 Example of a simple <link linkend="BLOCK">block</link> action. Say you've
6723 seen an ad on your favourite page on example.com that you want to get rid of.
6724 You have right-clicked the image, selected <quote>copy image location</quote>
6725 and pasted the URL below while removing the leading http://, into a
6726 <literal>{ +block{} }</literal> section. Note that <literal>{ +handle-as-image
6727 }</literal> need not be specified, since all URLs ending in
6728 <literal>.gif</literal> will be tagged as images by the general rules as set
6729 in default.action anyway:
6733 { +<link linkend="BLOCK">block</link>{Nasty ads.} }
6734 www.example.com/nasty-ads/sponsor\.gif
6735 another.example.net/more/junk/here/</screen>
6738 The URLs of dynamically generated banners, especially from large banner
6739 farms, often don't use the well-known image file name extensions, which
6740 makes it impossible for <application>Privoxy</application> to guess
6741 the file type just by looking at the URL.
6742 You can use the <literal>+block-as-image</literal> alias defined above for
6744 Note that objects which match this rule but then turn out NOT to be an
6745 image are typically rendered as a <quote>broken image</quote> icon by the
6746 browser. Use cautiously.
6754 ar.atwola.com/</screen>
6757 Now you noticed that the default configuration breaks Forbes Magazine,
6758 but you were too lazy to find out which action is the culprit, and you
6759 were again too lazy to give <link linkend="contact">feedback</link>, so
6760 you just used the <literal>fragile</literal> alias on the site, and
6761 -- <emphasis>whoa!</emphasis> -- it worked. The <literal>fragile</literal>
6762 aliases disables those actions that are most likely to break a site. Also,
6763 good for testing purposes to see if it is <application>Privoxy</application>
6764 that is causing the problem or not. We later find other regular sites
6765 that misbehave, and add those to our personalized list of troublemakers:
6772 .mybank.com</screen>
6775 You like the <quote>fun</quote> text replacements in <filename>default.filter</filename>,
6776 but it is disabled in the distributed actions file.
6777 So you'd like to turn it on in your private,
6778 update-safe config, once and for all:
6782 { +<link linkend="filter-fun">filter{fun}</link> }
6783 / # For ALL sites!</screen>
6786 Note that the above is not really a good idea: There are exceptions
6787 to the filters in <filename>default.action</filename> for things that
6788 really shouldn't be filtered, like code on CVS->Web interfaces. Since
6789 <filename>user.action</filename> has the last word, these exceptions
6790 won't be valid for the <quote>fun</quote> filtering specified here.
6794 You might also worry about how your favourite free websites are
6795 funded, and find that they rely on displaying banner advertisements
6796 to survive. So you might want to specifically allow banners for those
6797 sites that you feel provide value to you:
6807 Note that <literal>allow-ads</literal> has been aliased to
6808 <literal>-<link linkend="block">block</link></literal>,
6809 <literal>-<link linkend="filter-banners-by-size">filter{banners-by-size}</link></literal>, and
6810 <literal>-<link linkend="filter-banners-by-link">filter{banners-by-link}</link></literal> above.
6814 Invoke another alias here to force an over-ride of the MIME type <literal>
6815 application/x-sh</literal> which typically would open a download type
6816 dialog. In my case, I want to look at the shell script, and then I can save
6817 it should I choose to.
6825 <filename>user.action</filename> is generally the best place to define
6826 exceptions and additions to the default policies of
6827 <filename>default.action</filename>. Some actions are safe to have their
6828 default policies set here though. So let's set a default policy to have a
6829 <quote>blank</quote> image as opposed to the checkerboard pattern for
6830 <emphasis>ALL</emphasis> sites. <quote>/</quote> of course matches all URL
6835 { +<link linkend="set-image-blocker">set-image-blocker{blank}</link> }
6836 / # ALL sites</screen>
6841 <!-- ~ End section ~ -->
6845 <!-- ~ End section ~ -->
6847 <!-- ~~~~~~~~ New section Header ~~~~~~~~~ -->
6849 <sect1 id="filter-file">
6850 <title>Filter Files</title>
6853 On-the-fly text substitutions need
6854 to be defined in a <quote>filter file</quote>. Once defined, they
6855 can then be invoked as an <quote>action</quote>.
6859 &my-app; supports three different pcrs-based filter actions:
6860 <literal><link linkend="filter">filter</link></literal> to
6861 rewrite the content that is send to the client,
6862 <literal><link linkend="client-header-filter">client-header-filter</link></literal>
6863 to rewrite headers that are send by the client, and
6864 <literal><link linkend="server-header-filter">server-header-filter</link></literal>
6865 to rewrite headers that are send by the server.
6869 &my-app; also supports two tagger actions:
6870 <literal><link linkend="client-header-tagger">client-header-tagger</link></literal>
6872 <literal><link linkend="server-header-tagger">server-header-tagger</link></literal>.
6873 Taggers and filters use the same syntax in the filter files, the difference
6874 is that taggers don't modify the text they are filtering, but use a rewritten
6875 version of the filtered text as tag. The tags can then be used to change the
6876 applying actions through sections with <link linkend="tag-pattern">tag-patterns</link>.
6880 Finally &my-app; supports the
6881 <literal><link linkend="external-filter">external-filter</link></literal> action
6882 to enable <literal><link linkend="external-filter-syntax">external filters</link></literal>
6883 written in proper programming languages.
6888 Multiple filter files can be defined through the <literal> <link
6889 linkend="filterfile">filterfile</link></literal> config directive. The filters
6890 as supplied by the developers are located in
6891 <filename>default.filter</filename>. It is recommended that any locally
6892 defined or modified filters go in a separately defined file such as
6893 <filename>user.filter</filename>.
6897 Common tasks for content filters are to eliminate common annoyances in
6898 HTML and JavaScript, such as pop-up windows,
6899 exit consoles, crippled windows without navigation tools, the
6900 infamous <BLINK> tag etc, to suppress images with certain
6901 width and height attributes (standard banner sizes or web-bugs),
6902 or just to have fun.
6906 Enabled content filters are applied to any content whose
6907 <quote>Content Type</quote> header is recognised as a sign
6908 of text-based content, with the exception of <literal>text/plain</literal>.
6909 Use the <link linkend="FORCE-TEXT-MODE">force-text-mode</link> action
6910 to also filter other content.
6914 Substitutions are made at the source level, so if you want to <quote>roll
6915 your own</quote> filters, you should first be familiar with HTML syntax,
6916 and, of course, regular expressions.
6920 Just like the <link linkend="actions-file">actions files</link>, the
6921 filter file is organized in sections, which are called <emphasis>filters</emphasis>
6922 here. Each filter consists of a heading line, that starts with one of the
6923 <emphasis>keywords</emphasis> <literal>FILTER:</literal>,
6924 <literal>CLIENT-HEADER-FILTER:</literal> or <literal>SERVER-HEADER-FILTER:</literal>
6925 followed by the filter's <emphasis>name</emphasis>, and a short (one line)
6926 <emphasis>description</emphasis> of what it does. Below that line
6927 come the <emphasis>jobs</emphasis>, i.e. lines that define the actual
6928 text substitutions. By convention, the name of a filter
6929 should describe what the filter <emphasis>eliminates</emphasis>. The
6930 comment is used in the <ulink url="http://config.privoxy.org/">web-based
6931 user interface</ulink>.
6935 Once a filter called <replaceable>name</replaceable> has been defined
6936 in the filter file, it can be invoked by using an action of the form
6937 +<literal><link linkend="filter">filter</link>{<replaceable>name</replaceable>}</literal>
6938 in any <link linkend="actions-file">actions file</link>.
6942 Filter definitions start with a header line that contains the filter
6943 type, the filter name and the filter description.
6944 A content filter header line for a filter called <quote>foo</quote> could look
6948 <screen>FILTER: foo Replace all "foo" with "bar"</screen>
6951 Below that line, and up to the next header line, come the jobs that
6952 define what text replacements the filter executes. They are specified
6953 in a syntax that imitates <ulink url="http://www.perl.org/">Perl</ulink>'s
6954 <literal>s///</literal> operator. If you are familiar with Perl, you
6955 will find this to be quite intuitive, and may want to look at the
6956 PCRS documentation for the subtle differences to Perl behaviour.
6960 Most notably, the non-standard option letter <literal>U</literal> is supported,
6961 which turns the default to ungreedy matching (add <literal>?</literal> to
6962 quantifiers to turn them greedy again).
6966 The non-standard option letter <literal>D</literal> (dynamic) allows
6967 to use the variables $host, $origin (the IP address the request came from),
6968 $path, $url and $listen-address (the address on which Privoxy accepted the
6969 client request. Example: 127.0.0.1:8118).
6970 They will be replaced with the value they refer to before the filter
6975 Note that '$' is a bad choice for a delimiter in a dynamic filter as you
6976 might end up with unintended variables if you use a variable name
6977 directly after the delimiter. Variables will be resolved without
6978 escaping anything, therefore you also have to be careful not to chose
6979 delimiters that appear in the replacement text. For example '<' should
6980 be save, while '?' will sooner or later cause conflicts with $url.
6984 The non-standard option letter <literal>T</literal> (trivial) prevents
6985 parsing for backreferences in the substitute. Use it if you want to include
6986 text like '$&' in your substitute without quoting.
6991 <ulink url="http://en.wikipedia.org/wiki/Regular_expressions"><quote>Regular
6992 Expressions</quote></ulink>, you might want to take a look at
6993 the <link linkend="regex">Appendix on regular expressions</link>, and
6994 see the <ulink url="http://perldoc.perl.org/perlre.html">Perl
6996 <ulink url="http://perldoc.perl.org/perlop.html">the
6997 <literal>s///</literal> operator's syntax</ulink> and <ulink
6998 url="http://perldoc.perl.org/perlre.html">Perl-style regular
6999 expressions</ulink> in general.
7000 The below examples might also help to get you started.
7004 <!-- ~~~~~~~~ New section Header ~~~~~~~~~ -->
7006 <sect2 id="filter-file-tut"><title>Filter File Tutorial</title>
7008 Now, let's complete our <quote>foo</quote> content filter. We have already defined
7009 the heading, but the jobs are still missing. Since all it does is to replace
7010 <quote>foo</quote> with <quote>bar</quote>, there is only one (trivial) job
7014 <screen>s/foo/bar/</screen>
7017 But wait! Didn't the comment say that <emphasis>all</emphasis> occurrences
7018 of <quote>foo</quote> should be replaced? Our current job will only take
7019 care of the first <quote>foo</quote> on each page. For global substitution,
7020 we'll need to add the <literal>g</literal> option:
7023 <screen>s/foo/bar/g</screen>
7026 Our complete filter now looks like this:
7029 <screen>FILTER: foo Replace all "foo" with "bar"
7030 s/foo/bar/g</screen>
7033 Let's look at some real filters for more interesting examples. Here you see
7034 a filter that protects against some common annoyances that arise from JavaScript
7035 abuse. Let's look at its jobs one after the other:
7040 FILTER: js-annoyances Get rid of particularly annoying JavaScript abuse
7042 # Get rid of JavaScript referrer tracking. Test page: http://www.randomoddness.com/untitled.htm
7044 s|(<script.*)document\.referrer(.*</script>)|$1"Not Your Business!"$2|Usg</screen>
7047 Following the header line and a comment, you see the job. Note that it uses
7048 <literal>|</literal> as the delimiter instead of <literal>/</literal>, because
7049 the pattern contains a forward slash, which would otherwise have to be escaped
7050 by a backslash (<literal>\</literal>).
7054 Now, let's examine the pattern: it starts with the text <literal><script.*</literal>
7055 enclosed in parentheses. Since the dot matches any character, and <literal>*</literal>
7056 means: <quote>Match an arbitrary number of the element left of myself</quote>, this
7057 matches <quote><script</quote>, followed by <emphasis>any</emphasis> text, i.e.
7058 it matches the whole page, from the start of the first <script> tag.
7062 That's more than we want, but the pattern continues: <literal>document\.referrer</literal>
7063 matches only the exact string <quote>document.referrer</quote>. The dot needed to
7064 be <emphasis>escaped</emphasis>, i.e. preceded by a backslash, to take away its
7065 special meaning as a joker, and make it just a regular dot. So far, the meaning is:
7066 Match from the start of the first <script> tag in a the page, up to, and including,
7067 the text <quote>document.referrer</quote>, if <emphasis>both</emphasis> are present
7068 in the page (and appear in that order).
7072 But there's still more pattern to go. The next element, again enclosed in parentheses,
7073 is <literal>.*</script></literal>. You already know what <literal>.*</literal>
7074 means, so the whole pattern translates to: Match from the start of the first <script>
7075 tag in a page to the end of the last <script> tag, provided that the text
7076 <quote>document.referrer</quote> appears somewhere in between.
7080 This is still not the whole story, since we have ignored the options and the parentheses:
7081 The portions of the page matched by sub-patterns that are enclosed in parentheses, will be
7082 remembered and be available through the variables <literal>$1, $2, ...</literal> in
7083 the substitute. The <literal>U</literal> option switches to ungreedy matching, which means
7084 that the first <literal>.*</literal> in the pattern will only <quote>eat up</quote> all
7085 text in between <quote><script</quote> and the <emphasis>first</emphasis> occurrence
7086 of <quote>document.referrer</quote>, and that the second <literal>.*</literal> will
7087 only span the text up to the <emphasis>first</emphasis> <quote></script></quote>
7088 tag. Furthermore, the <literal>s</literal> option says that the match may span
7089 multiple lines in the page, and the <literal>g</literal> option again means that the
7090 substitution is global.
7094 So, to summarize, the pattern means: Match all scripts that contain the text
7095 <quote>document.referrer</quote>. Remember the parts of the script from
7096 (and including) the start tag up to (and excluding) the string
7097 <quote>document.referrer</quote> as <literal>$1</literal>, and the part following
7098 that string, up to and including the closing tag, as <literal>$2</literal>.
7102 Now the pattern is deciphered, but wasn't this about substituting things? So
7103 lets look at the substitute: <literal>$1"Not Your Business!"$2</literal> is
7104 easy to read: The text remembered as <literal>$1</literal>, followed by
7105 <literal>"Not Your Business!"</literal> (<emphasis>including</emphasis>
7106 the quotation marks!), followed by the text remembered as <literal>$2</literal>.
7107 This produces an exact copy of the original string, with the middle part
7108 (the <quote>document.referrer</quote>) replaced by <literal>"Not Your
7109 Business!"</literal>.
7113 The whole job now reads: Replace <quote>document.referrer</quote> by
7114 <literal>"Not Your Business!"</literal> wherever it appears inside a
7115 <script> tag. Note that this job won't break JavaScript syntax,
7116 since both the original and the replacement are syntactically valid
7117 string objects. The script just won't have access to the referrer
7118 information anymore.
7122 We'll show you two other jobs from the JavaScript taming department, but
7123 this time only point out the constructs of special interest:
7127 # The status bar is for displaying link targets, not pointless blahblah
7129 s/window\.status\s*=\s*(['"]).*?\1/dUmMy=1/ig</screen>
7132 <literal>\s</literal> stands for whitespace characters (space, tab, newline,
7133 carriage return, form feed), so that <literal>\s*</literal> means: <quote>zero
7134 or more whitespace</quote>. The <literal>?</literal> in <literal>.*?</literal>
7135 makes this matching of arbitrary text ungreedy. (Note that the <literal>U</literal>
7136 option is not set). The <literal>['"]</literal> construct means: <quote>a single
7137 <emphasis>or</emphasis> a double quote</quote>. Finally, <literal>\1</literal> is
7138 a back-reference to the first parenthesis just like <literal>$1</literal> above,
7139 with the difference that in the <emphasis>pattern</emphasis>, a backslash indicates
7140 a back-reference, whereas in the <emphasis>substitute</emphasis>, it's the dollar.
7144 So what does this job do? It replaces assignments of single- or double-quoted
7145 strings to the <quote>window.status</quote> object with a dummy assignment
7146 (using a variable name that is hopefully odd enough not to conflict with
7147 real variables in scripts). Thus, it catches many cases where e.g. pointless
7148 descriptions are displayed in the status bar instead of the link target when
7149 you move your mouse over links.
7153 # Kill OnUnload popups. Yummy. Test: http://www.zdnet.com/zdsubs/yahoo/tree/yfs.html
7155 s/(<body [^>]*)onunload(.*>)/$1never$2/iU</screen>
7159 <ulink url="http://www.w3.org/TR/2000/REC-DOM-Level-2-Events-20001113/events.html#Events-eventgroupings-htmlevents">OnUnload
7160 event binding</ulink> in the HTML DOM was a <emphasis>CRIME</emphasis>.
7161 When I close a browser window, I want it to close and die. Basta.
7162 This job replaces the <quote>onunload</quote> attribute in
7163 <quote><body></quote> tags with the dummy word <literal>never</literal>.
7164 Note that the <literal>i</literal> option makes the pattern matching
7165 case-insensitive. Also note that ungreedy matching alone doesn't always guarantee
7166 a minimal match: In the first parenthesis, we had to use <literal>[^>]*</literal>
7167 instead of <literal>.*</literal> to prevent the match from exceeding the
7168 <body> tag if it doesn't contain <quote>OnUnload</quote>, but the page's
7173 The last example is from the fun department:
7177 FILTER: fun Fun text replacements
7179 # Spice the daily news:
7181 s/microsoft(?!\.com)/MicroSuck/ig</screen>
7184 Note the <literal>(?!\.com)</literal> part (a so-called negative lookahead)
7185 in the job's pattern, which means: Don't match, if the string
7186 <quote>.com</quote> appears directly following <quote>microsoft</quote>
7187 in the page. This prevents links to microsoft.com from being trashed, while
7188 still replacing the word everywhere else.
7192 # Buzzword Bingo (example for extended regex syntax)
7194 s* industry[ -]leading \
7196 | customer[ -]focused \
7197 | market[ -]driven \
7198 | award[ -]winning # Comments are OK, too! \
7199 | high[ -]performance \
7200 | solutions[ -]based \
7204 *<font color="red"><b>BINGO!</b></font> \
7208 The <literal>x</literal> option in this job turns on extended syntax, and allows for
7209 e.g. the liberal use of (non-interpreted!) whitespace for nicer formatting.
7217 <!-- ~~~~~~~~ New section Header ~~~~~~~~~ -->
7219 <sect2 id="predefined-filters"><title>The Pre-defined Filters</title>
7223 Note each filter is also listed in the +filter action section above. Please
7224 keep these listings in sync.
7229 The distribution <filename>default.filter</filename> file contains a selection of
7230 pre-defined filters for your convenience:
7235 <term><emphasis>js-annoyances</emphasis></term>
7238 The purpose of this filter is to get rid of particularly annoying JavaScript abuse.
7244 replaces JavaScript references to the browser's referrer information
7245 with the string "Not Your Business!". This compliments the <literal><link
7246 linkend="hide-referrer">hide-referrer</link></literal> action on the content level.
7251 removes the bindings to the DOM's
7252 <ulink url="http://www.w3.org/TR/2000/REC-DOM-Level-2-Events-20001113/events.html#Events-eventgroupings-htmlevents">unload
7253 event</ulink> which we feel has no right to exist and is responsible for most <quote>exit consoles</quote>, i.e.
7254 nasty windows that pop up when you close another one.
7259 removes code that causes new windows to be opened with undesired properties, such as being
7260 full-screen, non-resizeable, without location, status or menu bar etc.
7265 Use with caution. This is an aggressive filter, and can break sites that
7266 rely heavily on JavaScript.
7272 <term><emphasis>js-events</emphasis></term>
7275 This is a very radical measure. It removes virtually all JavaScript event bindings, which
7276 means that scripts can not react to user actions such as mouse movements or clicks, window
7277 resizing etc, anymore. Use with caution!
7280 We <emphasis>strongly discourage</emphasis> using this filter as a default since it breaks
7281 many legitimate scripts. It is meant for use only on extra-nasty sites (should you really
7288 <term><emphasis>html-annoyances</emphasis></term>
7291 This filter will undo many common instances of HTML based abuse.
7294 The <literal>BLINK</literal> and <literal>MARQUEE</literal> tags
7295 are neutralized (yeah baby!), and browser windows will be created as
7296 resizeable (as of course they should be!), and will have location,
7297 scroll and menu bars -- even if specified otherwise.
7303 <term><emphasis>content-cookies</emphasis></term>
7306 Most cookies are set in the HTTP dialog, where they can be intercepted
7308 <literal><link linkend="crunch-incoming-cookies">crunch-incoming-cookies</link></literal>
7309 and <literal><link linkend="crunch-outgoing-cookies">crunch-outgoing-cookies</link></literal>
7310 actions. But web sites increasingly make use of HTML meta tags and JavaScript
7311 to sneak cookies to the browser on the content level.
7314 This filter disables most HTML and JavaScript code that reads or sets
7315 cookies. It cannot detect all clever uses of these types of code, so it
7316 should not be relied on as an absolute fix. Use it wherever you would also
7317 use the cookie crunch actions.
7323 <term><emphasis>refresh-tags</emphasis></term>
7326 Disable any refresh tags if the interval is greater than nine seconds (so
7327 that redirections done via refresh tags are not destroyed). This is useful
7328 for dial-on-demand setups, or for those who find this HTML feature
7335 <term><emphasis>unsolicited-popups</emphasis></term>
7338 This filter attempts to prevent only <quote>unsolicited</quote> pop-up
7339 windows from opening, yet still allow pop-up windows that the user
7340 has explicitly chosen to open. It was added in version 3.0.1,
7341 as an improvement over earlier such filters.
7344 Technical note: The filter works by redefining the window.open JavaScript
7345 function to a dummy function, <literal>PrivoxyWindowOpen()</literal>,
7346 during the loading and rendering phase of each HTML page access, and
7347 restoring the function afterward.
7350 This is recommended only for browsers that cannot perform this function
7351 reliably themselves. And be aware that some sites require such windows
7352 in order to function normally. Use with caution.
7358 <term><emphasis>all-popups</emphasis></term>
7361 Attempt to prevent <emphasis>all</emphasis> pop-up windows from opening.
7362 Note this should be used with even more discretion than the above, since
7363 it is more likely to break some sites that require pop-ups for normal
7364 usage. Use with caution.
7370 <term><emphasis>img-reorder</emphasis></term>
7373 This is a helper filter that has no value if used alone. It makes the
7374 <literal>banners-by-size</literal> and <literal>banners-by-link</literal>
7375 (see below) filters more effective and should be enabled together with them.
7381 <term><emphasis>banners-by-size</emphasis></term>
7384 This filter removes image tags purely based on what size they are. Fortunately
7385 for us, many ads and banner images tend to conform to certain standardized
7386 sizes, which makes this filter quite effective for ad stripping purposes.
7389 Occasionally this filter will cause false positives on images that are not ads,
7390 but just happen to be of one of the standard banner sizes.
7393 Recommended only for those who require extreme ad blocking. The default
7394 block rules should catch 95+% of all ads <emphasis>without</emphasis> this filter enabled.
7400 <term><emphasis>banners-by-link</emphasis></term>
7403 This is an experimental filter that attempts to kill any banners if
7404 their URLs seem to point to known or suspected click trackers. It is currently
7405 not of much value and is not recommended for use by default.
7411 <term><emphasis>webbugs</emphasis></term>
7414 Webbugs are small, invisible images (technically 1X1 GIF images), that
7415 are used to track users across websites, and collect information on them.
7416 As an HTML page is loaded by the browser, an embedded image tag causes the
7417 browser to contact a third-party site, disclosing the tracking information
7418 through the requested URL and/or cookies for that third-party domain, without
7419 the user ever becoming aware of the interaction with the third-party site.
7420 HTML-ized spam also uses a similar technique to verify email addresses.
7423 This filter removes the HTML code that loads such <quote>webbugs</quote>.
7429 <term><emphasis>tiny-textforms</emphasis></term>
7432 A rather special-purpose filter that can be used to enlarge textareas (those
7433 multi-line text boxes in web forms) and turn off hard word wrap in them.
7434 It was written for the sourceforge.net tracker system where such boxes are
7435 a nuisance, but it can be handy on other sites, too.
7438 It is not recommended to use this filter as a default.
7444 <term><emphasis>jumping-windows</emphasis></term>
7447 Many consider windows that move, or resize themselves to be abusive. This filter
7448 neutralizes the related JavaScript code. Note that some sites might not display
7449 or behave as intended when using this filter. Use with caution.
7455 <term><emphasis>frameset-borders</emphasis></term>
7458 Some web designers seem to assume that everyone in the world will view their
7459 web sites using the same browser brand and version, screen resolution etc,
7460 because only that assumption could explain why they'd use static frame sizes,
7461 yet prevent their frames from being resized by the user, should they be too
7462 small to show their whole content.
7465 This filter removes the related HTML code. It should only be applied to sites
7472 <term><emphasis>demoronizer</emphasis></term>
7475 Many Microsoft products that generate HTML use non-standard extensions (read:
7476 violations) of the ISO 8859-1 aka Latin-1 character set. This can cause those
7477 HTML documents to display with errors on standard-compliant platforms.
7480 This filter translates the MS-only characters into Latin-1 equivalents.
7481 It is not necessary when using MS products, and will cause corruption of
7482 all documents that use 8-bit character sets other than Latin-1. It's mostly
7483 worthwhile for Europeans on non-MS platforms, if weird garbage characters
7484 sometimes appear on some pages, or user agents that don't correct for this on
7487 My version of Mozilla (ancient) shows little square boxes for quote
7488 characters, and apostrophes on moronized pages. So many pages have this, I
7489 can read them fine now. HB 08/27/06
7496 <term><emphasis>shockwave-flash</emphasis></term>
7499 A filter for shockwave haters. As the name suggests, this filter strips code
7500 out of web pages that is used to embed shockwave flash objects.
7508 <term><emphasis>quicktime-kioskmode</emphasis></term>
7511 Change HTML code that embeds Quicktime objects so that kioskmode, which
7512 prevents saving, is disabled.
7518 <term><emphasis>fun</emphasis></term>
7521 Text replacements for subversive browsing fun. Make fun of your favorite
7522 Monopolist or play buzzword bingo.
7528 <term><emphasis>crude-parental</emphasis></term>
7531 A demonstration-only filter that shows how <application>Privoxy</application>
7532 can be used to delete web content on a keyword basis.
7538 <term><emphasis>ie-exploits</emphasis></term>
7541 An experimental collection of text replacements to disable malicious HTML and JavaScript
7542 code that exploits known security holes in Internet Explorer.
7545 Presently, it only protects against Nimda and a cross-site scripting bug, and
7546 would need active maintenance to provide more substantial protection.
7552 <term><emphasis>site-specifics</emphasis></term>
7555 Some web sites have very specific problems, the cure for which doesn't apply
7556 anywhere else, or could even cause damage on other sites.
7559 This is a collection of such site-specific cures which should only be applied
7560 to the sites they were intended for, which is what the supplied
7561 <filename>default.action</filename> file does. Users shouldn't need to change
7562 anything regarding this filter.
7568 <term><emphasis>google</emphasis></term>
7571 A CSS based block for Google text ads. Also removes a width limitation
7572 and the toolbar advertisement.
7578 <term><emphasis>yahoo</emphasis></term>
7581 Another CSS based block, this time for Yahoo text ads. And removes
7582 a width limitation as well.
7588 <term><emphasis>msn</emphasis></term>
7591 Another CSS based block, this time for MSN text ads. And removes
7592 tracking URLs, as well as a width limitation.
7598 <term><emphasis>blogspot</emphasis></term>
7601 Cleans up some Blogspot blogs. Read the fine print before using this one!
7604 This filter also intentionally removes some navigation stuff and sets the
7605 page width to 100%. As a result, some rounded <quote>corners</quote> would
7606 appear to early or not at all and as fixing this would require a browser
7607 that understands background-size (CSS3), they are removed instead.
7613 <term><emphasis>xml-to-html</emphasis></term>
7616 Server-header filter to change the Content-Type from xml to html.
7622 <term><emphasis>html-to-xml</emphasis></term>
7625 Server-header filter to change the Content-Type from html to xml.
7631 <term><emphasis>no-ping</emphasis></term>
7634 Removes the non-standard <literal>ping</literal> attribute from
7635 anchor and area HTML tags.
7641 <term><emphasis>hide-tor-exit-notation</emphasis></term>
7644 Client-header filter to remove the <command>Tor</command> exit node notation
7645 found in Host and Referer headers.
7648 If &my-app; and <command>Tor</command> are chained and &my-app;
7649 is configured to use socks4a, one can use <quote>http://www.example.org.foobar.exit/</quote>
7650 to access the host <quote>www.example.org</quote> through the
7651 <command>Tor</command> exit node <quote>foobar</quote>.
7654 As the HTTP client isn't aware of this notation, it treats the
7655 whole string <quote>www.example.org.foobar.exit</quote> as host and uses it
7656 for the <quote>Host</quote> and <quote>Referer</quote> headers. From the
7657 server's point of view the resulting headers are invalid and can cause problems.
7660 An invalid <quote>Referer</quote> header can trigger <quote>hot-linking</quote>
7661 protections, an invalid <quote>Host</quote> header will make it impossible for
7662 the server to find the right vhost (several domains hosted on the same IP address).
7665 This client-header filter removes the <quote>foo.exit</quote> part in those headers
7666 to prevent the mentioned problems. Note that it only modifies
7667 the HTTP headers, it doesn't make it impossible for the server
7668 to detect your <command>Tor</command> exit node based on the IP address
7669 the request is coming from.
7676 <term><emphasis> </emphasis></term>
7689 <!-- ~~~~~~~~ New section Header ~~~~~~~~~ -->
7690 <sect2 id="external-filter-syntax"><title>External filter syntax</title>
7692 External filters are scripts or programs that can modify the content in
7693 case common <literal><link linkend="filter">filters</link></literal>
7694 aren't powerful enough.
7697 External filters can be written in any language the platform &my-app; runs
7701 They are controlled with the
7702 <literal><link linkend="external-filter">external-filter</link></literal> action
7703 and have to be defined in the <literal><link linkend="filterfile">filterfile</link></literal>
7707 The header looks like any other filter, but instead of pcrs jobs, external
7708 filters contain a single job which can be a program or a shell script (which
7709 may call other scripts or programs).
7712 External filters read the content from STDIN and write the rewritten
7714 The environment variables PRIVOXY_URL, PRIVOXY_PATH, PRIVOXY_HOST,
7715 PRIVOXY_ORIGIN, PRIVOXY_LISTEN_ADDRESS can be used to get some details
7716 about the client request.
7719 &my-app; will temporary store the content to filter in the
7720 <literal><link linkend="temporary-directory">temporary-directory</link></literal>.
7724 EXTERNAL-FILTER: cat Pointless example filter that doesn't actually modify the content
7727 # Incorrect reimplementation of the filter above in POSIX shell.
7729 # Note that it's a single job that spans multiple lines, the line
7730 # breaks are not passed to the shell, thus the semicolons are required.
7732 # If the script isn't trivial, it is recommended to put it into an external file.
7734 # In general, writing external filters entirely in POSIX shell is not
7735 # considered a good idea.
7736 EXTERNAL-FILTER: cat2 Pointless example filter that despite its name may actually modify the content
7742 EXTERNAL-FILTER: rotate-image Rotate an image by 180 degree. Test filter with limited value.
7743 /usr/local/bin/convert - -rotate 180 -
7745 EXTERNAL-FILTER: citation-needed Adds a "[citation needed]" tag to an image. The coordinates may need adjustment.
7746 /usr/local/bin/convert - -pointsize 16 -fill white -annotate +17+418 "[citation needed]" -
7751 Currently external filters are executed with &my-app;'s privileges!
7752 Only use external filters you understand and trust.
7756 External filters are experimental and the syntax may change in the future.
7762 <!-- ~ End section ~ -->
7766 <!-- ~~~~~ New section ~~~~~ -->
7768 <sect1 id="templates">
7769 <title>Privoxy's Template Files</title>
7771 All <application>Privoxy</application> built-in pages, i.e. error pages such as the
7772 <ulink url="http://show-the-404-error.page"><quote>404 - No Such Domain</quote>
7773 error page</ulink>, the <ulink
7774 url="http://ads.bannerserver.example.com/nasty-ads/sponsor.html"><quote>BLOCKED</quote>
7776 and all pages of its <ulink url="http://config.privoxy.org/">web-based
7777 user interface</ulink>, are generated from <emphasis>templates</emphasis>.
7778 (<application>Privoxy</application> must be running for the above links to work as
7783 These templates are stored in a subdirectory of the <link linkend="confdir">configuration
7784 directory</link> called <filename>templates</filename>. On Unixish platforms,
7786 <ulink url="file:///etc/privoxy/templates/"><filename>/etc/privoxy/templates/</filename></ulink>.
7790 The templates are basically normal HTML files, but with place-holders (called symbols
7791 or exports), which <application>Privoxy</application> fills at run time. It
7792 is possible to edit the templates with a normal text editor, should you want
7793 to customize them. (<emphasis>Not recommended for the casual
7794 user</emphasis>). Should you create your own custom templates, you should use
7795 the <filename>config</filename> setting <link linkend="templdir">templdir</link>
7796 to specify an alternate location, so your templates do not get overwritten
7800 Note that just like in configuration files, lines starting
7801 with <literal>#</literal> are ignored when the templates are filled in.
7805 The place-holders are of the form <literal>@name@</literal>, and you will
7806 find a list of available symbols, which vary from template to template,
7807 in the comments at the start of each file. Note that these comments are not
7808 always accurate, and that it's probably best to look at the existing HTML
7809 code to find out which symbols are supported and what they are filled in with.
7813 A special application of this substitution mechanism is to make whole
7814 blocks of HTML code disappear when a specific symbol is set. We use this
7815 for many purposes, one of them being to include the beta warning in all
7816 our user interface (CGI) pages when <application>Privoxy</application>
7817 is in an alpha or beta development stage:
7821 <!-- @if-unstable-start -->
7823 ... beta warning HTML code goes here ...
7825 <!-- if-unstable-end@ --></screen>
7828 If the "unstable" symbol is set, everything in between and including
7829 <literal>@if-unstable-start</literal> and <literal>if-unstable-end@</literal>
7830 will disappear, leaving nothing but an empty comment:
7833 <screen><!-- --></screen>
7836 There's also an if-then-else construct and an <literal>#include</literal>
7837 mechanism, but you'll sure find out if you are inclined to edit the
7842 All templates refer to a style located at
7843 <ulink url="http://config.privoxy.org/send-stylesheet"><literal>http://config.privoxy.org/send-stylesheet</literal></ulink>.
7844 This is, of course, locally served by <application>Privoxy</application>
7845 and the source for it can be found and edited in the
7846 <filename>cgi-style.css</filename> template.
7851 <!-- ~ End section ~ -->
7855 <!-- ~~~~~ New section ~~~~~ -->
7857 <sect1 id="contact"><title>Contacting the Developers, Bug Reporting and Feature
7860 <!-- Include contacting.sgml boilerplate: -->
7862 <!-- end boilerplate -->
7866 <!-- ~ End section ~ -->
7869 <!-- ~~~~~ New section ~~~~~ -->
7870 <sect1 id="copyright"><title>Privoxy Copyright, License and History</title>
7872 <!-- Include copyright.sgml: -->
7874 <!-- end copyright -->
7877 <application>Privoxy</application> is free software; you can
7878 redistribute and/or modify its source code under the terms
7879 of the <citetitle>GNU General Public License</citetitle>
7880 as published by the Free Software Foundation, either version 2
7881 of the license, or (at your option) any later version.
7885 The same is true for <application>Privoxy</application> binaries
7886 unless they are linked with
7887 <ulink url="https://tls.mbed.org/">mbed TLS</ulink> in which
7888 case you can redistribute them and/or modify them under the terms
7889 of the <citetitle>GNU General Public License</citetitle>
7890 as published by the Free Software Foundation, either version 3
7891 of the license, or (at your option) any later version.
7895 Both licenses are included in the next section.
7898 <!-- ~~~~~ New section ~~~~~ -->
7899 <sect2 id="license"><title>License</title>
7901 <sect3 id="gplv2"><title>GNU General Public License version 2</title>
7902 <screen><![ RCDATA [ &GPLv2; ]]></screen>
7905 <sect3 id="gplv3"><title>GNU General Public License version 3</title>
7906 <screen><![ RCDATA [ &GPLv3; ]]></screen>
7910 <!-- ~ End section ~ -->
7913 <!-- ~~~~~ New section ~~~~~ -->
7915 <sect2 id="history"><title>History</title>
7916 <!-- Include history.sgml: -->
7918 <!-- end history -->
7921 <sect2 id="authors"><title>Authors</title>
7922 <!-- Include p-authors.sgml: -->
7924 <!-- end authors -->
7929 <!-- ~ End section ~ -->
7932 <!-- ~~~~~ New section ~~~~~ -->
7933 <sect1 id="seealso"><title>See Also</title>
7934 <!-- Include seealso.sgml: -->
7936 <!-- end seealso -->
7941 <!-- ~~~~~ New section ~~~~~ -->
7942 <sect1 id="appendix"><title>Appendix</title>
7945 <!-- ~~~~~ New section ~~~~~ -->
7947 <title>Regular Expressions</title>
7949 <application>Privoxy</application> uses Perl-style <quote>regular
7950 expressions</quote> in its <link linkend="actions-file">actions
7951 files</link> and <link linkend="filter-file">filter file</link>,
7952 through the <ulink url="http://www.pcre.org/">PCRE</ulink> and
7955 <ulink url="http://www.oesterhelt.org/pcrs/">PCRS</ulink> libraries.
7957 <application>PCRS</application> libraries.
7961 If you are reading this, you probably don't understand what <quote>regular
7962 expressions</quote> are, or what they can do. So this will be a very brief
7963 introduction only. A full explanation would require a <ulink
7964 url="http://www.oreilly.com/catalog/regex/">book</ulink> ;-)
7968 Regular expressions provide a language to describe patterns that can be
7969 run against strings of characters (letter, numbers, etc), to see if they
7970 match the string or not. The patterns are themselves (sometimes complex)
7971 strings of literal characters, combined with wild-cards, and other special
7972 characters, called meta-characters. The <quote>meta-characters</quote> have
7973 special meanings and are used to build complex patterns to be matched against.
7974 Perl Compatible Regular Expressions are an especially convenient
7975 <quote>dialect</quote> of the regular expression language.
7979 To make a simple analogy, we do something similar when we use wild-card
7980 characters when listing files with the <command>dir</command> command in DOS.
7981 <literal>*.*</literal> matches all filenames. The <quote>special</quote>
7982 character here is the asterisk which matches any and all characters. We can be
7983 more specific and use <literal>?</literal> to match just individual
7984 characters. So <quote>dir file?.text</quote> would match
7985 <quote>file1.txt</quote>, <quote>file2.txt</quote>, etc. We are pattern
7986 matching, using a similar technique to <quote>regular expressions</quote>!
7990 Regular expressions do essentially the same thing, but are much, much more
7991 powerful. There are many more <quote>special characters</quote> and ways of
7992 building complex patterns however. Let's look at a few of the common ones,
7993 and then some examples:
7998 <emphasis>.</emphasis> - Matches any single character, e.g. <quote>a</quote>,
7999 <quote>A</quote>, <quote>4</quote>, <quote>:</quote>, or <quote>@</quote>.
8005 <emphasis>?</emphasis> - The preceding character or expression is matched ZERO or ONE
8012 <emphasis>+</emphasis> - The preceding character or expression is matched ONE or MORE
8019 <emphasis>*</emphasis> - The preceding character or expression is matched ZERO or MORE
8026 <emphasis>\</emphasis> - The <quote>escape</quote> character denotes that
8027 the following character should be taken literally. This is used where one of the
8028 special characters (e.g. <quote>.</quote>) needs to be taken literally and
8029 not as a special meta-character. Example: <quote>example\.com</quote>, makes
8030 sure the period is recognized only as a period (and not expanded to its
8031 meta-character meaning of any single character).
8037 <emphasis>[ ]</emphasis> - Characters enclosed in brackets will be matched if
8038 any of the enclosed characters are encountered. For instance, <quote>[0-9]</quote>
8039 matches any numeric digit (zero through nine). As an example, we can combine
8040 this with <quote>+</quote> to match any digit one of more times: <quote>[0-9]+</quote>.
8046 <emphasis>( )</emphasis> - parentheses are used to group a sub-expression,
8047 or multiple sub-expressions.
8053 <emphasis>|</emphasis> - The <quote>bar</quote> character works like an
8054 <quote>or</quote> conditional statement. A match is successful if the
8055 sub-expression on either side of <quote>|</quote> matches. As an example:
8056 <quote>/(this|that) example/</quote> uses grouping and the bar character
8057 and would match either <quote>this example</quote> or <quote>that
8058 example</quote>, and nothing else.
8063 These are just some of the ones you are likely to use when matching URLs with
8064 <application>Privoxy</application>, and is a long way from a definitive
8065 list. This is enough to get us started with a few simple examples which may
8066 be more illuminating:
8070 <emphasis><literal>/.*/banners/.*</literal></emphasis> - A simple example
8071 that uses the common combination of <quote>.</quote> and <quote>*</quote> to
8072 denote any character, zero or more times. In other words, any string at all.
8073 So we start with a literal forward slash, then our regular expression pattern
8074 (<quote>.*</quote>) another literal forward slash, the string
8075 <quote>banners</quote>, another forward slash, and lastly another
8076 <quote>.*</quote>. We are building
8077 a directory path here. This will match any file with the path that has a
8078 directory named <quote>banners</quote> in it. The <quote>.*</quote> matches
8079 any characters, and this could conceivably be more forward slashes, so it
8080 might expand into a much longer looking path. For example, this could match:
8081 <quote>/eye/hate/spammers/banners/annoy_me_please.gif</quote>, or just
8082 <quote>/banners/annoying.html</quote>, or almost an infinite number of other
8083 possible combinations, just so it has <quote>banners</quote> in the path
8088 And now something a little more complex:
8092 <emphasis><literal>/.*/adv((er)?ts?|ertis(ing|ements?))?/</literal></emphasis> -
8093 We have several literal forward slashes again (<quote>/</quote>), so we are
8094 building another expression that is a file path statement. We have another
8095 <quote>.*</quote>, so we are matching against any conceivable sub-path, just so
8096 it matches our expression. The only true literal that <emphasis>must
8097 match</emphasis> our pattern is <application>adv</application>, together with
8098 the forward slashes. What comes after the <quote>adv</quote> string is the
8103 Remember the <quote>?</quote> means the preceding expression (either a
8104 literal character or anything grouped with <quote>(...)</quote> in this case)
8105 can exist or not, since this means either zero or one match. So
8106 <quote>((er)?ts?|ertis(ing|ements?))</quote> is optional, as are the
8107 individual sub-expressions: <quote>(er)</quote>,
8108 <quote>(ing|ements?)</quote>, and the <quote>s</quote>. The <quote>|</quote>
8109 means <quote>or</quote>. We have two of those. For instance,
8110 <quote>(ing|ements?)</quote>, can expand to match either <quote>ing</quote>
8111 <emphasis>OR</emphasis> <quote>ements?</quote>. What is being done here, is an
8112 attempt at matching as many variations of <quote>advertisement</quote>, and
8113 similar, as possible. So this would expand to match just <quote>adv</quote>,
8114 or <quote>advert</quote>, or <quote>adverts</quote>, or
8115 <quote>advertising</quote>, or <quote>advertisement</quote>, or
8116 <quote>advertisements</quote>. You get the idea. But it would not match
8117 <quote>advertizements</quote> (with a <quote>z</quote>). We could fix that by
8118 changing our regular expression to:
8119 <quote>/.*/adv((er)?ts?|erti(s|z)(ing|ements?))?/</quote>, which would then match
8124 <emphasis><literal>/.*/advert[0-9]+\.(gif|jpe?g)</literal></emphasis> - Again
8125 another path statement with forward slashes. Anything in the square brackets
8126 <quote>[ ]</quote> can be matched. This is using <quote>0-9</quote> as a
8127 shorthand expression to mean any digit one through nine. It is the same as
8128 saying <quote>0123456789</quote>. So any digit matches. The <quote>+</quote>
8129 means one or more of the preceding expression must be included. The preceding
8130 expression here is what is in the square brackets -- in this case, any digit
8131 one through nine. Then, at the end, we have a grouping: <quote>(gif|jpe?g)</quote>.
8132 This includes a <quote>|</quote>, so this needs to match the expression on
8133 either side of that bar character also. A simple <quote>gif</quote> on one side, and the other
8134 side will in turn match either <quote>jpeg</quote> or <quote>jpg</quote>,
8135 since the <quote>?</quote> means the letter <quote>e</quote> is optional and
8136 can be matched once or not at all. So we are building an expression here to
8137 match image GIF or JPEG type image file. It must include the literal
8138 string <quote>advert</quote>, then one or more digits, and a <quote>.</quote>
8139 (which is now a literal, and not a special character, since it is escaped
8140 with <quote>\</quote>), and lastly either <quote>gif</quote>, or
8141 <quote>jpeg</quote>, or <quote>jpg</quote>. Some possible matches would
8142 include: <quote>//advert1.jpg</quote>,
8143 <quote>/nasty/ads/advert1234.gif</quote>,
8144 <quote>/banners/from/hell/advert99.jpg</quote>. It would not match
8145 <quote>advert1.gif</quote> (no leading slash), or
8146 <quote>/adverts232.jpg</quote> (the expression does not include an
8147 <quote>s</quote>), or <quote>/advert1.jsp</quote> (<quote>jsp</quote> is not
8148 in the expression anywhere).
8152 We are barely scratching the surface of regular expressions here so that you
8153 can understand the default <application>Privoxy</application>
8154 configuration files, and maybe use this knowledge to customize your own
8155 installation. There is much, much more that can be done with regular
8156 expressions. Now that you know enough to get started, you can learn more on
8161 More reading on Perl Compatible Regular expressions:
8162 <ulink url="http://perldoc.perl.org/perlre.html">http://perldoc.perl.org/perlre.html</ulink>
8166 For information on regular expression based substitutions and their applications
8167 in filters, please see the <link linkend="filter-file">filter file tutorial</link>
8172 <!-- ~ End section ~ -->
8175 <!-- ~~~~~ New section ~~~~~ -->
8176 <sect2 id="internal-pages">
8177 <title>Privoxy's Internal Pages</title>
8180 Since <application>Privoxy</application> proxies each requested
8181 web page, it is easy for <application>Privoxy</application> to
8182 trap certain special URLs. In this way, we can talk directly to
8183 <application>Privoxy</application>, and see how it is
8184 configured, see how our rules are being applied, change these
8185 rules and other configuration options, and even turn
8186 <application>Privoxy's</application> filtering off, all with
8191 The URLs listed below are the special ones that allow direct access
8192 to <application>Privoxy</application>. Of course,
8193 <application>Privoxy</application> must be running to access these. If
8194 not, you will get a friendly error message. Internet access is not
8206 <ulink url="http://config.privoxy.org/">http://config.privoxy.org/</ulink>
8210 There is a shortcut: <ulink url="http://p.p/">http://p.p/</ulink> (But it
8211 doesn't provide a fall-back to a real page, in case the request is not
8212 sent through <application>Privoxy</application>)
8218 View and toggle client tags:
8222 <ulink url="http://config.privoxy.org/client-tags">http://config.privoxy.org/client-tags</ulink>
8229 Show information about the current configuration, including viewing and
8230 editing of actions files:
8234 <ulink url="http://config.privoxy.org/show-status">http://config.privoxy.org/show-status</ulink>
8241 Show the browser's request headers:
8245 <ulink url="http://config.privoxy.org/show-request">http://config.privoxy.org/show-request</ulink>
8252 Show which actions apply to a URL and why:
8256 <ulink url="http://config.privoxy.org/show-url-info">http://config.privoxy.org/show-url-info</ulink>
8263 Toggle Privoxy on or off. This feature can be turned off/on in the main
8264 <filename>config</filename> file. When toggled <quote>off</quote>, <quote>Privoxy</quote>
8265 continues to run, but only as a pass-through proxy, with no actions taking
8270 <ulink url="http://config.privoxy.org/toggle">http://config.privoxy.org/toggle</ulink>
8274 Short cuts. Turn off, then on:
8278 <ulink url="http://config.privoxy.org/toggle?set=disable">http://config.privoxy.org/toggle?set=disable</ulink>
8283 <ulink url="http://config.privoxy.org/toggle?set=enable">http://config.privoxy.org/toggle?set=enable</ulink>
8293 <!-- ~~~~~ New section ~~~~~ -->
8295 <title>Chain of Events</title>
8297 Let's take a quick look at how some of <application>Privoxy's</application>
8298 core features are triggered, and the ensuing sequence of events when a web
8299 page is requested by your browser:
8305 First, your web browser requests a web page. The browser knows to send
8306 the request to <application>Privoxy</application>, which will in turn,
8307 relay the request to the remote web server after passing the following
8313 <application>Privoxy</application> traps any request for its own internal CGI
8314 pages (e.g <ulink url="http://p.p/">http://p.p/</ulink>) and sends the CGI page back to the browser.
8319 Next, <application>Privoxy</application> checks to see if the URL
8321 linkend="BLOCK"><quote>+block</quote></link> patterns. If
8322 so, the URL is then blocked, and the remote web server will not be contacted.
8323 <link linkend="HANDLE-AS-IMAGE"><quote>+handle-as-image</quote></link>
8325 <link linkend="HANDLE-AS-EMPTY-DOCUMENT"><quote>+handle-as-empty-document</quote></link>
8326 are then checked, and if there is no match, an
8327 HTML <quote>BLOCKED</quote> page is sent back to the browser. Otherwise, if
8328 it does match, an image is returned for the former, and an empty text
8329 document for the latter. The type of image would depend on the setting of
8330 <link linkend="SET-IMAGE-BLOCKER"><quote>+set-image-blocker</quote></link>
8331 (blank, checkerboard pattern, or an HTTP redirect to an image elsewhere).
8336 Untrusted URLs are blocked. If URLs are being added to the
8337 <filename>trust</filename> file, then that is done.
8342 If the URL pattern matches the <link
8343 linkend="FAST-REDIRECTS"><quote>+fast-redirects</quote></link> action,
8344 it is then processed. Unwanted parts of the requested URL are stripped.
8349 Now the rest of the client browser's request headers are processed. If any
8350 of these match any of the relevant actions (e.g. <link
8351 linkend="HIDE-USER-AGENT"><quote>+hide-user-agent</quote></link>,
8352 etc.), headers are suppressed or forged as determined by these actions and
8358 Now the web server starts sending its response back (i.e. typically a web
8364 First, the server headers are read and processed to determine, among other
8365 things, the MIME type (document type) and encoding. The headers are then
8366 filtered as determined by the
8367 <link linkend="CRUNCH-INCOMING-COOKIES"><quote>+crunch-incoming-cookies</quote></link>,
8368 <link linkend="SESSION-COOKIES-ONLY"><quote>+session-cookies-only</quote></link>,
8369 and <link linkend="DOWNGRADE-HTTP-VERSION"><quote>+downgrade-http-version</quote></link>
8375 If any <link linkend="FILTER"><quote>+filter</quote></link> action
8377 linkend="DEANIMATE-GIFS"><quote>+deanimate-gifs</quote></link>
8378 action applies (and the document type fits the action), the rest of the page is
8379 read into memory (up to a configurable limit). Then the filter rules (from
8380 <filename>default.filter</filename> and any other filter files) are
8381 processed against the buffered content. Filters are applied in the order
8382 they are specified in one of the filter files. Animated GIFs, if present,
8383 are reduced to either the first or last frame, depending on the action
8384 setting.The entire page, which is now filtered, is then sent by
8385 <application>Privoxy</application> back to your browser.
8388 If neither a <link linkend="FILTER"><quote>+filter</quote></link> action
8390 linkend="DEANIMATE-GIFS"><quote>+deanimate-gifs</quote></link>
8391 matches, then <application>Privoxy</application> passes the raw data through
8392 to the client browser as it becomes available.
8397 As the browser receives the now (possibly filtered) page content, it
8398 reads and then requests any URLs that may be embedded within the page
8399 source, e.g. ad images, stylesheets, JavaScript, other HTML documents (e.g.
8400 frames), sounds, etc. For each of these objects, the browser issues a
8401 separate request (this is easily viewable in <application>Privoxy's</application>
8402 logs). And each such request is in turn processed just as above. Note that a
8403 complex web page will have many, many such embedded URLs. If these
8404 secondary requests are to a different server, then quite possibly a very
8405 differing set of actions is triggered.
8412 NOTE: This is somewhat of a simplistic overview of what happens with each URL
8413 request. For the sake of brevity and simplicity, we have focused on
8414 <application>Privoxy's</application> core features only.
8420 <!-- ~~~~~ New section ~~~~~ -->
8421 <sect2 id="actionsanat">
8422 <title>Troubleshooting: Anatomy of an Action</title>
8425 The way <application>Privoxy</application> applies
8426 <link linkend="ACTIONS">actions</link> and <link linkend="FILTER">filters</link>
8427 to any given URL can be complex, and not always so
8428 easy to understand what is happening. And sometimes we need to be able to
8429 <emphasis>see</emphasis> just what <application>Privoxy</application> is
8430 doing. Especially, if something <application>Privoxy</application> is doing
8431 is causing us a problem inadvertently. It can be a little daunting to look at
8432 the actions and filters files themselves, since they tend to be filled with
8433 <link linkend="regex">regular expressions</link> whose consequences are not
8438 One quick test to see if <application>Privoxy</application> is causing a problem
8439 or not, is to disable it temporarily. This should be the first troubleshooting
8440 step (be sure to flush caches afterward!). Looking at the
8441 logs is a good idea too. (Note that both the toggle feature and logging are
8442 enabled via <filename>config</filename> file settings, and may need to be
8443 turned <quote>on</quote>.)
8446 Another easy troubleshooting step to try is if you have done any
8447 customization of your installation, revert back to the installed
8448 defaults and see if that helps. There are times the developers get complaints
8449 about one thing or another, and the problem is more related to a customized
8450 configuration issue.
8454 <application>Privoxy</application> also provides the
8455 <ulink url="http://config.privoxy.org/show-url-info">http://config.privoxy.org/show-url-info</ulink>
8456 page that can show us very specifically how <application>actions</application>
8457 are being applied to any given URL. This is a big help for troubleshooting.
8461 First, enter one URL (or partial URL) at the prompt, and then
8462 <application>Privoxy</application> will tell us
8463 how the current configuration will handle it. This will not
8464 help with filtering effects (i.e. the <link
8465 linkend="FILTER"><quote>+filter</quote></link> action) from
8466 one of the filter files since this is handled very
8467 differently and not so easy to trap! It also will not tell you about any other
8468 URLs that may be embedded within the URL you are testing. For instance, images
8469 such as ads are expressed as URLs within the raw page source of HTML pages. So
8470 you will only get info for the actual URL that is pasted into the prompt area
8471 -- not any sub-URLs. If you want to know about embedded URLs like ads, you
8472 will have to dig those out of the HTML source. Use your browser's <quote>View
8473 Page Source</quote> option for this. Or right click on the ad, and grab the
8478 Let's try an example, <ulink url="http://google.com">google.com</ulink>,
8479 and look at it one section at a time in a sample configuration (your real
8480 configuration may vary):
8484 Matches for http://www.google.com:
8486 In file: default.action <guibutton>[ View ]</guibutton> <guibutton>[ Edit ]</guibutton>
8488 {+change-x-forwarded-for{block}
8489 +deanimate-gifs {last}
8490 +fast-redirects {check-decoded-url}
8491 +filter {refresh-tags}
8492 +filter {img-reorder}
8493 +filter {banners-by-size}
8495 +filter {jumping-windows}
8496 +filter {ie-exploits}
8497 +hide-from-header {block}
8498 +hide-referrer {forge}
8499 +session-cookies-only
8500 +set-image-blocker {pattern}
8503 { -session-cookies-only }
8509 In file: user.action <guibutton>[ View ]</guibutton> <guibutton>[ Edit ]</guibutton>
8510 (no matches in this file)
8514 This is telling us how we have defined our
8515 <link linkend="ACTIONS"><quote>actions</quote></link>, and
8516 which ones match for our test case, <quote>google.com</quote>.
8517 Displayed is all the actions that are available to us. Remember,
8518 the <literal>+</literal> sign denotes <quote>on</quote>. <literal>-</literal>
8519 denotes <quote>off</quote>. So some are <quote>on</quote> here, but many
8520 are <quote>off</quote>. Each example we try may provide a slightly different
8521 end result, depending on our configuration directives.
8525 is for our <filename>default.action</filename> file. The large, multi-line
8526 listing, is how the actions are set to match for all URLs, i.e. our default
8527 settings. If you look at your <quote>actions</quote> file, this would be the
8528 section just below the <quote>aliases</quote> section near the top. This
8529 will apply to all URLs as signified by the single forward slash at the end
8530 of the listing -- <quote> / </quote>.
8534 But we have defined additional actions that would be exceptions to these general
8535 rules, and then we list specific URLs (or patterns) that these exceptions
8536 would apply to. Last match wins. Just below this then are two explicit
8537 matches for <quote>.google.com</quote>. The first is negating our previous
8538 cookie setting, which was for <link
8539 linkend="SESSION-COOKIES-ONLY"><quote>+session-cookies-only</quote></link>
8540 (i.e. not persistent). So we will allow persistent cookies for google, at
8541 least that is how it is in this example. The second turns
8542 <emphasis>off</emphasis> any <link
8543 linkend="FAST-REDIRECTS"><quote>+fast-redirects</quote></link>
8544 action, allowing this to take place unmolested. Note that there is a leading
8545 dot here -- <quote>.google.com</quote>. This will match any hosts and
8546 sub-domains, in the google.com domain also, such as
8547 <quote>www.google.com</quote> or <quote>mail.google.com</quote>. But it would not
8548 match <quote>www.google.de</quote>! So, apparently, we have these two actions
8549 defined as exceptions to the general rules at the top somewhere in the lower
8550 part of our <filename>default.action</filename> file, and
8551 <quote>google.com</quote> is referenced somewhere in these latter sections.
8555 Then, for our <filename>user.action</filename> file, we again have no hits.
8556 So there is nothing google-specific that we might have added to our own, local
8557 configuration. If there was, those actions would over-rule any actions from
8558 previously processed files, such as <filename>default.action</filename>.
8559 <filename>user.action</filename> typically has the last word. This is the
8560 best place to put hard and fast exceptions,
8564 And finally we pull it all together in the bottom section and summarize how
8565 <application>Privoxy</application> is applying all its <quote>actions</quote>
8566 to <quote>google.com</quote>:
8574 +change-x-forwarded-for{block}
8575 -client-header-filter{hide-tor-exit-notation}
8576 -content-type-overwrite
8577 -crunch-client-header
8578 -crunch-if-none-match
8579 -crunch-incoming-cookies
8580 -crunch-outgoing-cookies
8581 -crunch-server-header
8582 +deanimate-gifs {last}
8583 -downgrade-http-version
8586 -filter {content-cookies}
8587 -filter {all-popups}
8588 -filter {banners-by-link}
8589 -filter {tiny-textforms}
8590 -filter {frameset-borders}
8591 -filter {demoronizer}
8592 -filter {shockwave-flash}
8593 -filter {quicktime-kioskmode}
8595 -filter {crude-parental}
8596 -filter {site-specifics}
8597 -filter {js-annoyances}
8598 -filter {html-annoyances}
8599 +filter {refresh-tags}
8600 -filter {unsolicited-popups}
8601 +filter {img-reorder}
8602 +filter {banners-by-size}
8604 +filter {jumping-windows}
8605 +filter {ie-exploits}
8612 -handle-as-empty-document
8614 -hide-accept-language
8615 -hide-content-disposition
8616 +hide-from-header {block}
8617 -hide-if-modified-since
8618 +hide-referrer {forge}
8621 -overwrite-last-modified
8622 -prevent-compression
8624 -server-header-filter{xml-to-html}
8625 -server-header-filter{html-to-xml}
8626 -session-cookies-only
8627 +set-image-blocker {pattern}
8631 Notice the only difference here to the previous listing, is to
8632 <quote>fast-redirects</quote> and <quote>session-cookies-only</quote>,
8633 which are activated specifically for this site in our configuration,
8634 and thus show in the <quote>Final Results</quote>.
8638 Now another example, <quote>ad.doubleclick.net</quote>:
8642 { +block{Domains starts with "ad"} }
8645 { +block{Domain contains "ad"} }
8648 { +block{Doubleclick banner server} +handle-as-image }
8649 .[a-vx-z]*.doubleclick.net
8653 We'll just show the interesting part here - the explicit matches. It is
8654 matched three different times. Two <quote>+block{}</quote> sections,
8655 and a <quote>+block{} +handle-as-image</quote>,
8656 which is the expanded form of one of our aliases that had been defined as:
8657 <quote>+block-as-image</quote>. (<link
8658 linkend="ALIASES"><quote>Aliases</quote></link> are defined in
8659 the first section of the actions file and typically used to combine more
8664 Any one of these would have done the trick and blocked this as an unwanted
8665 image. This is unnecessarily redundant since the last case effectively
8666 would also cover the first. No point in taking chances with these guys
8667 though ;-) Note that if you want an ad or obnoxious
8668 URL to be invisible, it should be defined as <quote>ad.doubleclick.net</quote>
8669 is done here -- as both a <link
8670 linkend="BLOCK"><quote>+block{}</quote></link>
8671 <emphasis>and</emphasis> an
8672 <link linkend="HANDLE-AS-IMAGE"><quote>+handle-as-image</quote></link>.
8673 The custom alias <quote><literal>+block-as-image</literal></quote> just
8674 simplifies the process and make it more readable.
8678 One last example. Let's try <quote>http://www.example.net/adsl/HOWTO/</quote>.
8679 This one is giving us problems. We are getting a blank page. Hmmm ...
8683 Matches for http://www.example.net/adsl/HOWTO/:
8685 In file: default.action <guibutton>[ View ]</guibutton> <guibutton>[ Edit ]</guibutton>
8689 +change-x-forwarded-for{block}
8690 -client-header-filter{hide-tor-exit-notation}
8691 -content-type-overwrite
8692 -crunch-client-header
8693 -crunch-if-none-match
8694 -crunch-incoming-cookies
8695 -crunch-outgoing-cookies
8696 -crunch-server-header
8698 -downgrade-http-version
8699 +fast-redirects {check-decoded-url}
8701 -filter {content-cookies}
8702 -filter {all-popups}
8703 -filter {banners-by-link}
8704 -filter {tiny-textforms}
8705 -filter {frameset-borders}
8706 -filter {demoronizer}
8707 -filter {shockwave-flash}
8708 -filter {quicktime-kioskmode}
8710 -filter {crude-parental}
8711 -filter {site-specifics}
8712 -filter {js-annoyances}
8713 -filter {html-annoyances}
8714 +filter {refresh-tags}
8715 -filter {unsolicited-popups}
8716 +filter {img-reorder}
8717 +filter {banners-by-size}
8719 +filter {jumping-windows}
8720 +filter {ie-exploits}
8727 -handle-as-empty-document
8729 -hide-accept-language
8730 -hide-content-disposition
8731 +hide-from-header{block}
8732 +hide-referer{forge}
8734 -overwrite-last-modified
8735 +prevent-compression
8737 -server-header-filter{xml-to-html}
8738 -server-header-filter{html-to-xml}
8739 +session-cookies-only
8740 +set-image-blocker{blank} }
8743 { +block{Path contains "ads".} +handle-as-image }
8748 Ooops, the <quote>/adsl/</quote> is matching <quote>/ads</quote> in our
8749 configuration! But we did not want this at all! Now we see why we get the
8750 blank page. It is actually triggering two different actions here, and
8751 the effects are aggregated so that the URL is blocked, and &my-app; is told
8752 to treat the block as if it were an image. But this is, of course, all wrong.
8753 We could now add a new action below this (or better in our own
8754 <filename>user.action</filename> file) that explicitly
8755 <emphasis>un</emphasis> blocks (
8756 <link linkend="BLOCK"><quote>{-block}</quote></link>) paths with
8757 <quote>adsl</quote> in them (remember, last match in the configuration
8758 wins). There are various ways to handle such exceptions. Example:
8767 Now the page displays ;-)
8768 Remember to flush your browser's caches when making these kinds of changes to
8769 your configuration to insure that you get a freshly delivered page! Or, try
8770 using <literal>Shift+Reload</literal>.
8774 But now what about a situation where we get no explicit matches like
8779 { +block{Path starts with "ads".} +handle-as-image }
8784 That actually was very helpful and pointed us quickly to where the problem
8785 was. If you don't get this kind of match, then it means one of the default
8786 rules in the first section of <filename>default.action</filename> is causing
8787 the problem. This would require some guesswork, and maybe a little trial and
8788 error to isolate the offending rule. One likely cause would be one of the
8789 <link linkend="FILTER"><quote>+filter</quote></link> actions.
8790 These tend to be harder to troubleshoot.
8791 Try adding the URL for the site to one of aliases that turn off
8792 <link linkend="FILTER"><quote>+filter</quote></link>:
8798 .worldpay.com # for quietpc.com
8805 <quote><literal>{ shop }</literal></quote> is an <quote>alias</quote> that expands to
8806 <quote><literal>{ -filter -session-cookies-only }</literal></quote>.
8807 Or you could do your own exception to negate filtering:
8812 # Disable ALL filter actions for sites in this section
8819 This would turn off all filtering for these sites. This is best
8820 put in <filename>user.action</filename>, for local site
8821 exceptions. Note that when a simple domain pattern is used by itself (without
8822 the subsequent path portion), all sub-pages within that domain are included
8823 automatically in the scope of the action.
8827 Images that are inexplicably being blocked, may well be hitting the
8828 <link linkend="FILTER-BANNERS-BY-SIZE"><quote>+filter{banners-by-size}</quote></link>
8830 that images of certain sizes are ad banners (works well
8831 <emphasis>most of the time</emphasis> since these tend to be standardized).
8835 <quote><literal>{ fragile }</literal></quote> is an alias that disables most
8836 actions that are the most likely to cause trouble. This can be used as a
8837 last resort for problem sites.
8842 # Handle with care: easy to break
8844 mybank.example.com</screen>
8848 <emphasis>Remember to flush caches!</emphasis> Note that the
8849 <literal>mail.google</literal> reference lacks the TLD portion (e.g.
8850 <quote>.com</quote>). This will effectively match any TLD with
8851 <literal>google</literal> in it, such as <literal>mail.google.de.</literal>,
8855 If this still does not work, you will have to go through the remaining
8856 actions one by one to find which one(s) is causing the problem.
8865 This program is free software; you can redistribute it
8866 and/or modify it under the terms of the GNU General
8867 Public License as published by the Free Software
8868 Foundation; either version 2 of the License, or (at
8869 your option) any later version.
8871 This program is distributed in the hope that it will
8872 be useful, but WITHOUT ANY WARRANTY; without even the
8873 implied warranty of MERCHANTABILITY or FITNESS FOR A
8874 PARTICULAR PURPOSE. See the GNU General Public
8875 License for more details.
8877 The GNU General Public License should be included with
8878 this file. If not, you can view it at
8879 http://www.gnu.org/copyleft/gpl.html
8880 or write to the Free Software Foundation, Inc.,
8881 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,