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13 <!entity p-authors SYSTEM "p-authors.sgml">
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15 <!entity changelog SYSTEM "changelog.sgml">
16 <!entity p-version "3.0.29">
17 <!entity p-status "UNRELEASED">
18 <!entity % p-authors-formal "INCLUDE"> <!-- include additional text, etc -->
19 <!entity % p-not-stable "INCLUDE">
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21 <!entity % p-text "IGNORE"> <!-- define we are not a text only doc -->
22 <!entity % p-doc "INCLUDE"> <!-- and we are a formal doc -->
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26 <!entity % p-supp-userman "IGNORE"> <!-- Omit some from supported.sgml -->
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30 <!entity my-app "<application>Privoxy</application>">
33 File : doc/source/user-manual.sgml
37 Copyright (C) 2001-2020 Privoxy Developers https://www.privoxy.org/
40 ========================================================================
41 NOTE: Please read developer-manual/documentation.html before touching
42 anything in this, or other Privoxy documentation.
43 ========================================================================
50 <title>Privoxy &p-version; User Manual</title>
54 <!-- Completely the wrong markup, but very little is allowed -->
55 <!-- in this part of an article. FIXME -->
56 <link linkend="copyright">Copyright</link> &my-copy; 2001-2020 by
57 <ulink url="https://www.privoxy.org/">Privoxy Developers</ulink>
63 Note: the following should generate a separate page, and a live link to it,
64 all nicely done. But it doesn't for some mysterious reason. Please leave
65 commented unless it can be fixed proper. For the time being, the
66 copyright/license declarations will be in their own sgml.
79 This is here to keep vim syntax file from breaking :/
80 If I knew enough to fix it, I would.
81 PLEASE DO NOT REMOVE! HB: hal@foobox.net
87 The <citetitle>Privoxy User Manual</citetitle> gives users information on how to
88 install, configure and use <ulink
89 url="https://www.privoxy.org/">Privoxy</ulink>.
92 <!-- Include privoxy.sgml boilerplate: -->
94 <!-- end privoxy.sgml -->
97 You can find the latest version of the <citetitle>Privoxy User Manual</citetitle> at <ulink
98 url="https://www.privoxy.org/user-manual/">https://www.privoxy.org/user-manual/</ulink>.
99 Please see the <link linkend="contact">Contact section</link> on how to
100 contact the developers.
107 <!-- ~~~~~ New section ~~~~~ -->
108 <sect1 label="1" id="introduction"><title>Introduction</title>
110 This documentation is included with the current &p-status; version of
111 <application>Privoxy</application>, &p-version;<![%p-not-stable;[,
112 and is mostly complete at this point. The most up to date reference for the
113 time being is still the comments in the source files and in the individual
114 configuration files. Development of a new version is currently nearing
115 completion, and includes significant changes and enhancements over
119 <!-- include only in non-stable versions -->
122 Since this is a &p-status; version, not all new features are well tested. This
123 documentation may be slightly out of sync as a result (especially with
124 <ulink url="https://www.privoxy.org/gitweb/?p=privoxy.git;a=summary">git sources</ulink>).
125 And there <emphasis>may be</emphasis> bugs, though hopefully
130 <!-- ~~~~~ New section ~~~~~ -->
131 <sect2 id="features"><title>Features</title>
133 In addition to the core
134 features of ad blocking and
135 <ulink url="http://en.wikipedia.org/wiki/Browser_cookie">cookie</ulink> management,
136 <application>Privoxy</application> provides many supplemental
137 features<![%p-not-stable;[, some of them currently under development]]>,
138 that give the end-user more control, more privacy and more freedom:
140 <!-- Include newfeatures.sgml boilerplate here: -->
142 <!-- end boilerplate -->
147 <!-- ~ End section ~ -->
150 <!-- ~~~~~ New section ~~~~~ -->
151 <sect1 id="installation"><title>Installation</title>
154 <application>Privoxy</application> is available both in convenient pre-compiled
155 packages for a wide range of operating systems, and as raw source code.
156 For most users, we recommend using the packages, which can be downloaded from our
157 <ulink url="https://sourceforge.net/projects/ijbswa/">Privoxy Project
163 On some platforms, the installer may remove previously installed versions, if
164 found. (See below for your platform). In any case <emphasis>be sure to backup
165 your old configuration if it is valuable to you.</emphasis> See the <link
166 linkend="upgradersnote">note to upgraders</link> section below.
169 <!-- ~~~~~ New section ~~~~~ -->
170 <sect2 id="installation-packages"><title>Binary Packages</title>
172 How to install the binary packages depends on your operating system:
175 <!-- XXX: The installation sections should be sorted -->
177 <!-- ~~~~~ New section ~~~~~ -->
178 <sect3 id="installation-deb"><title>Debian and Ubuntu</title>
180 DEBs can be installed with <literal>apt-get install privoxy</literal>,
181 and will use <filename>/etc/privoxy</filename> for the location of
186 <!-- ~~~~~ New section ~~~~~ -->
187 <sect3 id="installation-pack-win"><title>Windows</title>
190 Just double-click the installer, which will guide you through
191 the installation process. You will find the configuration files
192 in the same directory as you installed <application>Privoxy</application> in.
195 Version 3.0.5 beta introduced full <application>Windows</application> service
196 functionality. On Windows only, the <application>Privoxy</application>
197 program has two new command line arguments to install and uninstall
198 <application>Privoxy</application> as a <emphasis>service</emphasis>.
202 <term>Arguments:</term>
205 <replaceable class="parameter">--install</replaceable>[:<replaceable class="parameter">service_name</replaceable>]
208 <replaceable class="parameter">--uninstall</replaceable>[:<replaceable class="parameter">service_name</replaceable>]
214 After invoking <application>Privoxy</application> with
215 <command>--install</command>, you will need to bring up the
216 <application>Windows</application> service console to assign the user you
217 want <application>Privoxy</application> to run under, and whether or not you
218 want it to run whenever the system starts. You can start the
219 <application>Windows</application> services console with the following
220 command: <command>services.msc</command>. If you do not take the manual step
221 of modifying <application>Privoxy's</application> service settings, it will
222 not start. Note too that you will need to give Privoxy a user account that
223 actually exists, or it will not be permitted to
224 write to its log and configuration files.
229 <!-- ~~~~~ New section ~~~~~ -->
230 <sect3 id="installation-os2"><title>OS/2</title>
233 First, make sure that no previous installations of
234 <application>Junkbuster</application> and / or
235 <application>Privoxy</application> are left on your
236 system. Check that no <application>Junkbuster</application>
237 or <application>Privoxy</application> objects are in
242 Then, just double-click the WarpIN self-installing archive, which will
243 guide you through the installation process. A shadow of the
244 <application>Privoxy</application> executable will be placed in your
245 startup folder so it will start automatically whenever OS/2 starts.
249 The directory you choose to install <application>Privoxy</application>
250 into will contain all of the configuration files.
254 <!-- ~~~~~ New section ~~~~~ -->
255 <sect3 id="installation-mac"><title>Mac OS X</title>
257 Installation instructions for the OS X platform depend upon whether
258 you downloaded a ready-built installation package (.pkg or .mpkg) or have
259 downloaded the source code.
262 <sect3 renderas="sect4" id="OS-X-install-from-package">
263 <title>Installation from ready-built package</title>
265 The downloaded file will either be a .pkg (for OS X 10.5 upwards) or a bzipped
266 .mpkg file (for OS X 10.4). The former can be double-clicked as is and the
267 installation will start; double-clicking the latter will unzip the .mpkg file
268 which can then be double-clicked to commence the installation.
271 The privoxy service will automatically start after a successful installation
272 (and thereafter every time your computer starts up) however you will need to
273 configure your web browser(s) to use it. To do so, configure them to use a
274 proxy for HTTP and HTTPS at the address 127.0.0.1:8118.
277 To prevent the privoxy service from automatically starting when your computer
278 starts up, remove or rename the file <literal>/Library/LaunchDaemons/org.ijbswa.privoxy.plist</literal>
279 (on OS X 10.5 and higher) or the folder named
280 <literal>/Library/StartupItems/Privoxy</literal> (on OS X 10.4 'Tiger').
283 To manually start or stop the privoxy service, use the scripts startPrivoxy.sh
284 and stopPrivoxy.sh supplied in /Applications/Privoxy. They must be run from an
285 administrator account, using sudo.
288 To uninstall, run /Applications/Privoxy/uninstall.command as sudo from an
289 administrator account.
292 <sect3 renderas="sect4" id="OS-X-install-from-source">
293 <title>Installation from source</title>
295 To build and install the Privoxy source code on OS X you will need to obtain
296 the macsetup module from the Privoxy Sourceforge CVS repository (refer to
297 Sourceforge help for details of how to set up a CVS client to have read-only
298 access to the repository). This module contains scripts that leverage the usual
299 open-source tools (available as part of Apple's free of charge Xcode
300 distribution or via the usual open-source software package managers for OS X
301 (MacPorts, Homebrew, Fink etc.) to build and then install the privoxy binary
302 and associated files. The macsetup module's README file contains complete
303 instructions for its use.
306 The privoxy service will automatically start after a successful installation
307 (and thereafter every time your computer starts up) however you will need to
308 configure your web browser(s) to use it. To do so, configure them to use a
309 proxy for HTTP and HTTPS at the address 127.0.0.1:8118.
312 To prevent the privoxy service from automatically starting when your computer
313 starts up, remove or rename the file <literal>/Library/LaunchDaemons/org.ijbswa.privoxy.plist</literal>
314 (on OS X 10.5 and higher) or the folder named
315 <literal>/Library/StartupItems/Privoxy</literal> (on OS X 10.4 'Tiger').
318 To manually start or stop the privoxy service, use the Privoxy Utility
319 for Mac OS X (also part of the macsetup module). This application can start
320 and stop the privoxy service and display its log and configuration files.
323 To uninstall, run the macsetup module's uninstall.sh as sudo from an
324 administrator account.
328 <!-- ~~~~~ New section ~~~~~ -->
329 <sect3 id="installation-freebsd"><title>FreeBSD</title>
332 Privoxy is part of FreeBSD's Ports Collection, you can build and install
333 it with <literal>cd /usr/ports/www/privoxy; make install clean</literal>.
339 <!-- ~~~~~ New section ~~~~~ -->
340 <sect2 id="installation-source"><title>Building from Source</title>
343 The most convenient way to obtain the <application>Privoxy</application> source
344 code is to download the source tarball from our
345 <ulink url="https://sourceforge.net/projects/ijbswa/files/Sources/">
346 project download page</ulink>,
347 or you can get the up-to-the-minute, possibly unstable, development version from
348 <ulink url="https://www.privoxy.org/">https://www.privoxy.org/</ulink>.
351 <!-- include buildsource.sgml boilerplate: -->
353 <!-- end boilerplate -->
356 <sect3 id="WINBUILD-CYGWIN"><title>Windows</title>
358 <sect4 id="WINBUILD-SETUP"><title>Setup</title>
360 Install the Cygwin utilities needed to build <application>Privoxy</application>.
361 If you have a 64 bit CPU (which most people do by now), get the
362 Cygwin setup-x86_64.exe program <ulink url="https://cygwin.com/setup-x86_64.exe">here</ulink>
363 (the .sig file is <ulink url="https://cygwin.com/setup-x86_64.exe.sig">here</ulink>).
366 Run the setup program and from View / Category select:
378 mingw64-i686-gcc-core
383 libxslt: GNOME XSLT library (runtime)
399 If you haven't already downloaded the Privoxy source code, get it now:
404 git clone https://www.privoxy.org/git/privoxy.git
408 Get the source code (.zip or .tar.gz) for tidy from
409 <ulink url="https://github.com/htacg/tidy-html5/releases">
410 https://github.com/htacg/tidy-html5/releases</ulink>,
411 unzip into <root-dir> and build the software:
415 cd tidy-html5-x.y.z/build/cmake
416 cmake ../.. -DCMAKE_BUILD_TYPE=Release -DBUILD_SHARED_LIB:BOOL=OFF -DCMAKE_INSTALL_PREFIX=/usr/local
421 If you want to be able to make a Windows release package, get the NSIS .zip file from
422 <!-- FIXME: which version(s) are known to work? -->
423 <ulink url="https://sourceforge.net/projects/nsis/files/NSIS%203/">
424 https://sourceforge.net/projects/nsis/files/NSIS%203/</ulink>
425 and extract the NSIS directory to <literal>privoxy/windows</literal>.
426 Then edit the windows/GNUmakefile to set the location of the NSIS executable - eg:
430 MAKENSIS = ./nsis/makensis.exe
435 <sect4 id="WINBUILD-BUILD"><title>Build</title>
438 To build just the Privoxy executable and not the whole installation package, do:
441 cd <root-dir>/privoxy
442 ./windows/MYconfigure && make
446 Privoxy uses the <ulink url="https://en.wikipedia.org/wiki/GNU_build_system">GNU Autotools</ulink>
447 for building software, so the process is:
450 $ autoheader # creates config.h.in
451 $ autoconf # uses config.h.in to create the configure shell script
452 $ ./configure [options] # creates GNUmakefile
453 $ make [options] # builds the program
457 The usual <literal>configure</literal> options for building a native Windows application under cygwin are
460 <literallayout class="Monospaced">
461 --host=i686-w64-mingw32
464 --enable-static-linking
466 --disable-dynamic-pcre
470 You can set the <literal>CFLAGS</literal> and <literal>LDFLAGS</literal> envars before
471 running <literal>configure</literal> to set compiler and linker flags. For example:
475 $ export CFLAGS="-O2" # set gcc optimization level
476 $ export LDFLAGS="-Wl,--nxcompat" # Enable DEP
477 $ ./configure --host=i686-w64-mingw32 --enable-mingw32 --enable-zlib \
478 > --enable-static-linking --disable-pthread --disable-dynamic-pcre
479 $ make # build Privoxy
483 See the <ulink url="../developer-manual/newrelease.html#NEWRELEASE-WINDOWS">Developer's Manual</ulink>
484 for building a Windows release package.
492 <!-- ~~~~~ New section ~~~~~ -->
493 <sect2 id="installation-keepupdated"><title>Keeping your Installation Up-to-Date</title>
496 If you wish to receive an email notification whenever we release updates of
497 <application>Privoxy</application> or the actions file, <ulink
498 url="https://lists.privoxy.org/mailman/listinfo/privoxy-announce">subscribe
499 to our announce mailing list</ulink>, privoxy-announce@lists.privoxy.org.
503 In order not to lose your personal changes and adjustments when updating
504 to the latest <literal>default.action</literal> file we <emphasis>strongly
505 recommend</emphasis> that you use <literal>user.action</literal> and
506 <literal>user.filter</literal> for your local
507 customizations of <application>Privoxy</application>. See the <link
508 linkend="actions-file">Chapter on actions files</link> for details.
516 <!-- ~ End section ~ -->
518 <!-- ~~~~~ New section ~~~~~ -->
519 <sect1 id="whatsnew">
520 <title>What's New in this Release</title>
524 <!-- ~~~~~ New section ~~~~~ -->
526 <sect2 id="upgradersnote">
527 <title>Note to Upgraders</title>
530 A quick list of things to be aware of before upgrading from earlier
531 versions of <application>Privoxy</application>:
538 The recommended way to upgrade &my-app; is to backup your old
539 configuration files, install the new ones, verify that &my-app;
540 is working correctly and finally merge back your changes using
541 <application>diff</application> and maybe <application>patch</application>.
544 There are a number of new features in each &my-app; release and
545 most of them have to be explicitly enabled in the configuration
546 files. Old configuration files obviously don't do that and due
547 to syntax changes using old configuration files with a new
548 &my-app; isn't always possible anyway.
553 Note that some installers remove earlier versions completely,
554 including configuration files, therefore you should really save
555 any important configuration files!
560 On the other hand, other installers don't overwrite existing configuration
561 files, thinking you will want to do that yourself.
566 In the default configuration only fatal errors are logged now.
567 You can change that in the <link linkend="DEBUG">debug section</link>
568 of the configuration file. You may also want to enable more verbose
569 logging until you verified that the new &my-app; version is working
576 Three other config file settings are now off by default:
577 <link linkend="enable-remote-toggle">enable-remote-toggle</link>,
578 <link linkend="enable-remote-http-toggle">enable-remote-http-toggle</link>,
579 and <link linkend="enable-edit-actions">enable-edit-actions</link>.
580 If you use or want these, you will need to explicitly enable them, and
581 be aware of the security issues involved.
588 What constitutes a <quote>default</quote> configuration has changed,
589 and you may want to review which actions are <quote>on</quote> by
590 default. This is primarily a matter of emphasis, but some features
591 you may have been used to, may now be <quote>off</quote> by default.
592 There are also a number of new actions and filters you may want to
593 consider, most of which are not fully incorporated into the default
594 settings as yet (see above).
601 The default actions setting is now <literal>Cautious</literal>. Previous
602 releases had a default setting of <literal>Medium</literal>. Experienced
603 users may want to adjust this, as it is fairly conservative by &my-app;
604 standards and past practices. See <ulink
605 url="http://config.privoxy.org/edit-actions-list?f=default">
606 http://config.privoxy.org/edit-actions-list?f=default</ulink>. New users
607 should try the default settings for a while before turning up the volume.
613 The default setting has filtering turned <emphasis>off</emphasis>, which
614 subsequently means that compression is <emphasis>on</emphasis>. Remember
615 that filtering does not work on compressed pages, so if you use, or want to
616 use, filtering, you will need to force compression off. Example:
619 { +<link linkend="filter">filter</link>{google} +<link linkend="prevent-compression">prevent-compression</link> }
622 Or if you use a number of filters, or filter many sites, you may just want
623 to turn off compression for all sites in
624 <filename>default.action</filename> (or
625 <filename>user.action</filename>).
632 Also, <link linkend="SESSION-COOKIES-ONLY">session-cookies-only</link> is
633 off by default now. If you've liked this feature in the past, you may want
634 to turn it back on in <filename>user.action</filename> now.
641 Some installers may not automatically start
642 <application>Privoxy</application> after installation.
652 <!-- ~~~~~ New section ~~~~~ -->
653 <sect1 id="quickstart"><title>Quickstart to Using Privoxy</title>
659 Install <application>Privoxy</application>. See the <link
660 linkend="installation">Installation Section</link> below for platform specific
667 Advanced users and those who want to offer <application>Privoxy</application>
668 service to more than just their local machine should check the <link
669 linkend="config">main config file</link>, especially the <link
670 linkend="access-control">security-relevant</link> options. These are
677 Start <application>Privoxy</application>, if the installation program has
678 not done this already (may vary according to platform). See the section
679 <link linkend="startup">Starting <application>Privoxy</application></link>.
685 Set your browser to use <application>Privoxy</application> as HTTP and
686 HTTPS (SSL) <ulink url="http://en.wikipedia.org/wiki/Proxy_server">proxy</ulink>
687 by setting the proxy configuration for address of
688 <literal>127.0.0.1</literal> and port <literal>8118</literal>.
689 <emphasis>DO NOT</emphasis> activate proxying for <literal>FTP</literal> or
690 any protocols besides HTTP and HTTPS (SSL) unless you intend to prevent your
691 browser from using these protocols.
697 Flush your browser's disk and memory caches, to remove any cached ad images.
698 If using <application>Privoxy</application> to manage
699 <ulink url="http://en.wikipedia.org/wiki/Browser_cookie">cookies</ulink>,
700 you should remove any currently stored cookies too.
706 A default installation should provide a reasonable starting point for
707 most. There will undoubtedly be occasions where you will want to adjust the
708 configuration, but that can be dealt with as the need arises. Little
709 to no initial configuration is required in most cases, you may want
711 <ulink url="config.html#ENABLE-EDIT-ACTIONS">web-based action editor</ulink> though.
712 Be sure to read the warnings first.
715 See the <link linkend="configuration">Configuration section</link> for more
716 configuration options, and how to customize your installation.
717 You might also want to look at the <link
718 linkend="quickstart-ad-blocking">next section</link> for a quick
719 introduction to how <application>Privoxy</application> blocks ads and
726 If you experience ads that slip through, innocent images that are
727 blocked, or otherwise feel the need to fine-tune
728 <application>Privoxy's</application> behavior, take a look at the <link
729 linkend="actions-file">actions files</link>. As a quick start, you might
730 find the <link linkend="act-examples">richly commented examples</link>
731 helpful. You can also view and edit the actions files through the <ulink
732 url="http://config.privoxy.org">web-based user interface</ulink>. The
733 Appendix <quote><link linkend="actionsanat">Troubleshooting: Anatomy of an
734 Action</link></quote> has hints on how to understand and debug actions that
735 <quote>misbehave</quote>.
741 Please see the section <link linkend="contact">Contacting the
742 Developers</link> on how to report bugs, problems with websites or to get
749 Now enjoy surfing with enhanced control, comfort and privacy!
756 <!-- ~~~~~ New section ~~~~~ -->
758 <sect2 id="quickstart-ad-blocking">
759 <title>Quickstart to Ad Blocking</title>
761 NOTE: This section is deliberately redundant for those that don't
762 want to read the whole thing (which is getting lengthy).
765 Ad blocking is but one of <application>Privoxy's</application>
766 array of features. Many of these features are for the technically minded advanced
767 user. But, ad and banner blocking is surely common ground for everybody.
770 This section will provide a quick summary of ad blocking so
771 you can get up to speed quickly without having to read the more extensive
772 information provided below, though this is highly recommended.
775 First a bit of a warning ... blocking ads is much like blocking SPAM: the
776 more aggressive you are about it, the more likely you are to block
777 things that were not intended. And the more likely that some things
778 may not work as intended. So there is a trade off here. If you want
779 extreme ad free browsing, be prepared to deal with more
780 <quote>problem</quote> sites, and to spend more time adjusting the
781 configuration to solve these unintended consequences. In short, there is
782 not an easy way to eliminate <emphasis>all</emphasis> ads. Either take
783 the easy way and settle for <emphasis>most</emphasis> ads blocked with the
784 default configuration, or jump in and tweak it for your personal surfing
785 habits and preferences.
788 Secondly, a brief explanation of <application>Privoxy's </application>
789 <quote>actions</quote>. <quote>Actions</quote> in this context, are
790 the directives we use to tell <application>Privoxy</application> to perform
791 some task relating to HTTP transactions (i.e. web browsing). We tell
792 <application>Privoxy</application> to take some <quote>action</quote>. Each
793 action has a unique name and function. While there are many potential
794 <application>actions</application> in <application>Privoxy's</application>
795 arsenal, only a few are used for ad blocking. <link
796 linkend="actions">Actions</link>, and <link linkend="actions-file">action
797 configuration files</link>, are explained in depth below.
800 Actions are specified in <application>Privoxy's</application> configuration,
801 followed by one or more URLs to which the action should apply. URLs
802 can actually be URL type <link linkend="af-patterns">patterns</link> that use
803 wildcards so they can apply potentially to a range of similar URLs. The
804 actions, together with the URL patterns are called a section.
807 When you connect to a website, the full URL will either match one or more
808 of the sections as defined in <application>Privoxy's</application> configuration,
809 or not. If so, then <application>Privoxy</application> will perform the
810 respective actions. If not, then nothing special happens. Furthermore, web
811 pages may contain embedded, secondary URLs that your web browser will
812 use to load additional components of the page, as it parses the
813 original page's HTML content. An ad image for instance, is just an URL
814 embedded in the page somewhere. The image itself may be on the same server,
815 or a server somewhere else on the Internet. Complex web pages will have many
816 such embedded URLs. &my-app; can deal with each URL individually, so, for
817 instance, the main page text is not touched, but images from such-and-such
822 The most important actions for basic ad blocking are: <literal><link
823 linkend="block">block</link></literal>, <literal><link
824 linkend="handle-as-image">handle-as-image</link></literal>,
826 linkend="handle-as-empty-document">handle-as-empty-document</link></literal>,and
827 <literal><link linkend="set-image-blocker">set-image-blocker</link></literal>:
834 <literal><link linkend="block">block</link></literal> - this is perhaps
835 the single most used action, and is particularly important for ad blocking.
836 This action stops any contact between your browser and any URL patterns
837 that match this action's configuration. It can be used for blocking ads,
838 but also anything that is determined to be unwanted. By itself, it simply
839 stops any communication with the remote server and sends
840 <application>Privoxy</application>'s own built-in BLOCKED page instead to
841 let you now what has happened (with some exceptions, see below).
847 <literal><link linkend="handle-as-image">handle-as-image</link></literal> -
848 tells <application>Privoxy</application> to treat this URL as an image.
849 <application>Privoxy</application>'s default configuration already does this
850 for all common image types (e.g. GIF), but there are many situations where this
851 is not so easy to determine. So we'll force it in these cases. This is particularly
852 important for ad blocking, since only if we know that it's an image of
853 some kind, can we replace it with an image of our choosing, instead of the
854 <application>Privoxy</application> BLOCKED page (which would only result in
855 a <quote>broken image</quote> icon). There are some limitations to this
856 though. For instance, you can't just brute-force an image substitution for
857 an entire HTML page in most situations.
863 <literal><link linkend="handle-as-empty-document">handle-as-empty-document</link></literal> -
864 sends an empty document instead of <application>Privoxy's</application>
865 normal BLOCKED HTML page. This is useful for file types that are neither
866 HTML nor images, such as blocking JavaScript files.
873 linkend="set-image-blocker">set-image-blocker</link></literal> - tells
874 <application>Privoxy</application> what to display in place of an ad image that
875 has hit a block rule. For this to come into play, the URL must match a
876 <literal><link linkend="block">block</link></literal> action somewhere in the
877 configuration, <emphasis>and</emphasis>, it must also match an
878 <literal><link linkend="handle-as-image">handle-as-image</link></literal> action.
881 The configuration options on what to display instead of the ad are:
885 <emphasis>pattern</emphasis> - a checkerboard pattern, so that an ad
886 replacement is obvious. This is the default.
891 <emphasis>blank</emphasis> - A very small empty GIF image is displayed.
892 This is the so-called <quote>invisible</quote> configuration option.
897 <emphasis>http://<URL></emphasis> - A redirect to any image anywhere
898 of the user's choosing (advanced usage).
906 Advanced users will eventually want to explore &my-app;
907 <literal><link linkend="filter">filters</link></literal> as well. Filters
908 are very different from <literal><link
909 linkend="block">blocks</link></literal>.
910 A <quote>block</quote> blocks a site, page, or unwanted contented. Filters
911 are a way of filtering or modifying what is actually on the page. An example
912 filter usage: a text replacement of <quote>no-no</quote> for
913 <quote>nasty-word</quote>. That is a very simple example. This process can be
914 used for ad blocking, but it is more in the realm of advanced usage and has
915 some pitfalls to be wary off.
919 The quickest way to adjust any of these settings is with your browser through
920 the special <application>Privoxy</application> editor at <ulink
921 url="http://config.privoxy.org/show-status">http://config.privoxy.org/show-status</ulink>
922 (shortcut: <ulink url="http://p.p/">http://p.p/show-status</ulink>). This
923 is an internal page, and does not require Internet access.
927 Note that as of <application>Privoxy</application> 3.0.7 beta the
928 action editor is disabled by default. Check the
929 <ulink url="config.html#ENABLE-EDIT-ACTIONS">enable-edit-actions
930 section in the configuration file</ulink> to learn why and in which
931 cases it's safe to enable again.
935 If you decided to enable the action editor, select the appropriate
936 <quote>actions</quote> file, and click
937 <quote><guibutton>Edit</guibutton></quote>. It is best to put personal or
938 local preferences in <filename>user.action</filename> since this is not
939 meant to be overwritten during upgrades, and will over-ride the settings in
940 other files. Here you can insert new <quote>actions</quote>, and URLs for ad
941 blocking or other purposes, and make other adjustments to the configuration.
942 <application>Privoxy</application> will detect these changes automatically.
946 A quick and simple step by step example:
953 Right click on the ad image to be blocked, then select
954 <quote><guimenuitem>Copy Link Location</guimenuitem></quote> from the
962 url="http://config.privoxy.org/show-status">http://config.privoxy.org/show-status</ulink>
967 Find <filename>user.action</filename> in the top section, and click
968 on <quote><guibutton>Edit</guibutton></quote>:
971 <!-- image of editor and actions files selections -->
972 <figure pgwide="0" float="0"><title>Actions Files in Use</title>
975 <imagedata fileref="files-in-use.jpg" format="jpg">
978 <phrase>[ Screenshot of Actions Files in Use ]</phrase>
986 You should have a section with only
987 <literal><link linkend="block">block</link></literal> listed under
988 <quote>Actions:</quote>.
989 If not, click a <quote><guibutton>Insert new section below</guibutton></quote>
990 button, and in the new section that just appeared, click the
991 <guibutton>Edit</guibutton> button right under the word <quote>Actions:</quote>.
992 This will bring up a list of all actions. Find
993 <literal><link linkend="block">block</link></literal> near the top, and click
994 in the <quote>Enabled</quote> column, then <quote><guibutton>Submit</guibutton></quote>
1000 Now, in the <literal><link linkend="block">block</link></literal> actions section,
1001 click the <quote><guibutton>Add</guibutton></quote> button, and paste the URL the
1002 browser got from <quote><guimenuitem>Copy Link Location</guimenuitem></quote>.
1003 Remove the <literal>http://</literal> at the beginning of the URL. Then, click
1004 <quote><guibutton>Submit</guibutton></quote> (or
1005 <quote><guibutton>OK</guibutton></quote> if in a pop-up window).
1010 Now go back to the original page, and press <keycap>SHIFT-Reload</keycap>
1011 (or flush all browser caches). The image should be gone now.
1018 This is a very crude and simple example. There might be good reasons to use a
1019 wildcard pattern match to include potentially similar images from the same
1020 site. For a more extensive explanation of <quote>patterns</quote>, and
1021 the entire actions concept, see <link linkend="actions-file">the Actions
1026 For advanced users who want to hand edit their config files, you might want
1027 to now go to the <link linkend="act-examples">Actions Files Tutorial</link>.
1028 The ideas explained therein also apply to the web-based editor.
1031 There are also various
1032 <link linkend="filter">filters</link> that can be used for ad blocking
1033 (filters are a special subset of actions). These
1034 fall into the <quote>advanced</quote> usage category, and are explained in
1035 depth in later sections.
1042 <!-- ~ End section ~ -->
1045 <!-- ~~~~~ New section ~~~~~ -->
1046 <sect1 id="startup">
1047 <title>Starting Privoxy</title>
1049 Before launching <application>Privoxy</application> for the first time, you
1050 will want to configure your browser(s) to use
1051 <application>Privoxy</application> as a HTTP and HTTPS (SSL)
1052 <ulink url="http://en.wikipedia.org/wiki/Proxy_server">proxy</ulink>. The default is
1053 127.0.0.1 (or localhost) for the proxy address, and port 8118 (earlier versions
1054 used port 8000). This is the one configuration step <emphasis>that must be done
1058 Please note that <application>Privoxy</application> can only proxy HTTP and
1059 HTTPS traffic. It will not work with FTP or other protocols.
1062 <!-- image of Mozilla Proxy configuration -->
1063 <figure pgwide="0" float="0"><title>Proxy Configuration Showing
1064 Mozilla/Netscape HTTP and HTTPS (SSL) Settings</title>
1067 <imagedata fileref="proxy_setup.jpg" format="jpg">
1070 <phrase>[ Screenshot of Mozilla Proxy Configuration ]</phrase>
1077 With <application>Firefox</application>, this is typically set under:
1081 <guibutton>Tools</guibutton> -> <guibutton>Options</guibutton> -> <guibutton>Advanced</guibutton> -> <guibutton>Network</guibutton> -><guibutton>Connection</guibutton> -> <guibutton>Settings</guibutton>
1085 Or optionally on some platforms:
1089 <guibutton>Edit</guibutton> -> <guibutton>Preferences</guibutton> -> <guibutton>General</guibutton> -> <guibutton>Connection Settings</guibutton> -> <guibutton>Manual Proxy Configuration</guibutton>
1094 With <application>Netscape</application> (and
1095 <application>Mozilla</application>), this can be set under:
1100 <!-- Mix ascii and gui art, something for everybody -->
1101 <!-- spacing on this is tricky -->
1102 <guibutton>Edit</guibutton> -> <guibutton>Preferences</guibutton> -> <guibutton>Advanced</guibutton> -> <guibutton>Proxies</guibutton> -> <guibutton>HTTP Proxy</guibutton>
1106 For <application>Internet Explorer v.5-7</application>:
1110 <guibutton>Tools</guibutton> -> <guibutton>Internet Options</guibutton> -> <guibutton>Connections</guibutton> -> <guibutton>LAN Settings</guibutton>
1114 Then, check <quote>Use Proxy</quote> and fill in the appropriate info
1115 (Address: 127.0.0.1, Port: 8118). Include HTTPS (SSL), if you want HTTPS
1116 proxy support too (sometimes labeled <quote>Secure</quote>). Make sure any
1117 checkboxes like <quote>Use the same proxy server for all protocols</quote> is
1118 <emphasis>UNCHECKED</emphasis>. You want only HTTP and HTTPS (SSL)!
1121 <!-- image of IE Proxy configuration -->
1122 <figure pgwide="0" float="0"><title>Proxy Configuration Showing
1123 Internet Explorer HTTP and HTTPS (Secure) Settings</title>
1126 <imagedata fileref="proxy2.jpg" format="jpg">
1129 <phrase>[ Screenshot of IE Proxy Configuration ]</phrase>
1136 After doing this, flush your browser's disk and memory caches to force a
1137 re-reading of all pages and to get rid of any ads that may be cached. Remove
1138 any <ulink url="http://en.wikipedia.org/wiki/Browser_cookie">cookies</ulink>,
1139 if you want <application>Privoxy</application> to manage that. You are now
1140 ready to start enjoying the benefits of using
1141 <application>Privoxy</application>!
1145 <application>Privoxy</application> itself is typically started by specifying the
1146 main configuration file to be used on the command line. If no configuration
1147 file is specified on the command line, <application>Privoxy</application>
1148 will look for a file named <filename>config</filename> in the current
1149 directory. Except on Win32 where it will try <filename>config.txt</filename>.
1152 <sect2 id="start-debian">
1153 <title>Debian</title>
1155 We use a script. Note that Debian typically starts &my-app; upon booting per
1156 default. It will use the file
1157 <filename>/etc/privoxy/config</filename> as its main configuration
1161 # /etc/init.d/privoxy start
1165 <sect2 id="start-freebsd">
1166 <title>FreeBSD and ElectroBSD</title>
1168 To start <application>Privoxy</application> upon booting, add
1169 "privoxy_enable='YES'" to <filename>/etc/rc.conf</filename>.
1170 <application>Privoxy</application> will use
1171 <filename>/usr/local/etc/privoxy/config</filename> as its main
1175 If you installed <application>Privoxy</application> into a jail, the
1176 paths above are relative to the jail root.
1179 To start <application>Privoxy</application> manually, run:
1182 # service privoxy onestart
1186 <sect2 id="start-windows">
1187 <title>Windows</title>
1189 Click on the &my-app; Icon to start <application>Privoxy</application>. If no configuration file is
1190 specified on the command line, <application>Privoxy</application> will look
1191 for a file named <filename>config.txt</filename>. Note that Windows will
1192 automatically start &my-app; when the system starts if you chose that option
1196 <application>Privoxy</application> can run with full Windows service functionality.
1197 On Windows only, the &my-app; program has two new command line arguments
1198 to install and uninstall &my-app; as a service. See the
1199 <link linkend="installation-pack-win">Windows Installation
1200 instructions</link> for details.
1204 <sect2 id="start-unices">
1205 <title>Generic instructions for Unix derivates (Solaris, NetBSD, HP-UX etc.)</title>
1207 Example Unix startup command:
1210 # /usr/sbin/privoxy --user privoxy /etc/privoxy/config
1213 Note that if you installed <application>Privoxy</application> through
1214 a package manager, the package will probably contain a platform-specific
1215 script or configuration file to start <application>Privoxy</application>
1220 <sect2 id="start-os2">
1223 During installation, <application>Privoxy</application> is configured to
1224 start automatically when the system restarts. You can start it manually by
1225 double-clicking on the <application>Privoxy</application> icon in the
1226 <application>Privoxy</application> folder.
1230 <sect2 id="start-macosx">
1231 <title>Mac OS X</title>
1233 The privoxy service will automatically start after a successful installation
1234 (and thereafter every time your computer starts up) however you will need to
1235 configure your web browser(s) to use it. To do so, configure them to use a
1236 proxy for HTTP and HTTPS at the address 127.0.0.1:8118.
1239 To prevent the privoxy service from automatically starting when your computer
1240 starts up, remove or rename the file <literal>/Library/LaunchDaemons/org.ijbswa.privoxy.plist</literal>
1241 (on OS X 10.5 and higher) or the folder named
1242 <literal>/Library/StartupItems/Privoxy</literal> (on OS X 10.4 'Tiger').
1245 To manually start or stop the privoxy service, use the scripts startPrivoxy.sh
1246 and stopPrivoxy.sh supplied in /Applications/Privoxy. They must be run from an
1247 administrator account, using sudo.
1255 See the section <link linkend="cmdoptions">Command line options</link> for
1259 must find a better place for this paragraph
1262 The included default configuration files should give a reasonable starting
1263 point. Most of the per site configuration is done in the
1264 <ulink url="actions-file.html"><quote>actions</quote></ulink> files. These are
1265 where various cookie actions are defined, ad and banner blocking, and other
1266 aspects of <application>Privoxy</application> configuration. There are several
1267 such files included, with varying levels of aggressiveness.
1271 You will probably want to keep an eye out for sites for which you may prefer
1272 persistent cookies, and add these to your actions configuration as needed. By
1273 default, most of these will be accepted only during the current browser
1274 session (aka <quote>session cookies</quote>), unless you add them to the
1275 configuration. If you want the browser to handle this instead, you will need
1276 to edit <filename>user.action</filename> (or through the web based interface)
1277 and disable this feature. If you use more than one browser, it would make
1278 more sense to let <application>Privoxy</application> handle this. In which
1279 case, the browser(s) should be set to accept all cookies.
1283 Another feature where you will probably want to define exceptions for trusted
1284 sites is the popup-killing (through <ulink
1285 url="actions-file.html#FILTER-POPUPS"><quote>+filter{popups}</quote></ulink>),
1286 because your favorite shopping, banking, or leisure site may need
1287 popups (explained below).
1291 <application>Privoxy</application> does not support all of the optional HTTP/1.1
1292 features yet. In the unlikely event that you experience inexplicable problems
1293 with browsers that use HTTP/1.1 per default
1294 (like <application>Mozilla</application> or recent versions of I.E.), you might
1295 try to force HTTP/1.0 compatibility. For Mozilla, look under <literal>Edit ->
1296 Preferences -> Debug -> Networking</literal>.
1297 Alternatively, set the <quote>+downgrade-http-version</quote> config option in
1298 <filename>default.action</filename> which will downgrade your browser's HTTP
1299 requests from HTTP/1.1 to HTTP/1.0 before processing them.
1303 After running <application>Privoxy</application> for a while, you can
1304 start to fine tune the configuration to suit your personal, or site,
1305 preferences and requirements. There are many, many aspects that can
1306 be customized. <quote>Actions</quote>
1307 can be adjusted by pointing your browser to
1308 <ulink url="http://config.privoxy.org/">http://config.privoxy.org/</ulink>
1309 (shortcut: <ulink url="http://p.p/">http://p.p/</ulink>),
1310 and then follow the link to <quote>View & Change the Current Configuration</quote>.
1311 (This is an internal page and does not require Internet access.)
1315 In fact, various aspects of <application>Privoxy</application>
1316 configuration can be viewed from this page, including
1317 current configuration parameters, source code version numbers,
1318 the browser's request headers, and <quote>actions</quote> that apply
1319 to a given URL. In addition to the actions file
1320 editor mentioned above, <application>Privoxy</application> can also
1321 be turned <quote>on</quote> and <quote>off</quote> (toggled) from this page.
1325 If you encounter problems, try loading the page without
1326 <application>Privoxy</application>. If that helps, enter the URL where
1327 you have the problems into <ulink url="http://p.p/show-url-info">the browser
1328 based rule tracing utility</ulink>. See which rules apply and why, and
1329 then try turning them off for that site one after the other, until the problem
1330 is gone. When you have found the culprit, you might want to turn the rest on
1335 If the above paragraph sounds gibberish to you, you might want to <link
1336 linkend="actions-file">read more about the actions concept</link>
1337 or even dive deep into the <link linkend="actionsanat">Appendix
1342 If you can't get rid of the problem at all, think you've found a bug in
1343 Privoxy, want to propose a new feature or smarter rules, please see the
1344 section <link linkend="contact"><quote>Contacting the
1345 Developers</quote></link> below.
1350 <!-- ~~~~~ New section ~~~~~ -->
1351 <sect2 id="cmdoptions">
1352 <title>Command Line Options</title>
1354 <application>Privoxy</application> may be invoked with the following
1355 command-line options:
1362 <emphasis>--config-test</emphasis>
1365 Exit after loading the configuration files before binding to
1366 the listen address. The exit code signals whether or not the
1367 configuration files have been successfully loaded.
1370 If the exit code is 1, at least one of the configuration files
1371 is invalid, if it is 0, all the configuration files have been
1372 successfully loaded (but may still contain errors that can
1373 currently only be detected at run time).
1376 This option doesn't affect the log setting, combination with
1377 <emphasis>--no-daemon</emphasis> is recommended if a configured
1378 log file shouldn't be used.
1383 <emphasis>--version</emphasis>
1386 Print version info and exit. Unix only.
1391 <emphasis>--help</emphasis>
1394 Print short usage info and exit. Unix only.
1399 <emphasis>--no-daemon</emphasis>
1402 Don't become a daemon, i.e. don't fork and become process group
1403 leader, and don't detach from controlling tty. Unix only.
1408 <emphasis>--pidfile FILE</emphasis>
1411 On startup, write the process ID to <emphasis>FILE</emphasis>. Delete the
1412 <emphasis>FILE</emphasis> on exit. Failure to create or delete the
1413 <emphasis>FILE</emphasis> is non-fatal. If no <emphasis>FILE</emphasis>
1414 option is given, no PID file will be used. Unix only.
1419 <emphasis>--user USER[.GROUP]</emphasis>
1422 After (optionally) writing the PID file, assume the user ID of
1423 <emphasis>USER</emphasis>, and if included the GID of GROUP. Exit if the
1424 privileges are not sufficient to do so. Unix only.
1429 <emphasis>--chroot</emphasis>
1432 Before changing to the user ID given in the <emphasis>--user</emphasis> option,
1433 chroot to that user's home directory, i.e. make the kernel pretend to the &my-app;
1434 process that the directory tree starts there. If set up carefully, this can limit
1435 the impact of possible vulnerabilities in &my-app; to the files contained in that hierarchy.
1441 <emphasis>--pre-chroot-nslookup hostname</emphasis>
1444 Specifies a hostname (for example www.privoxy.org) to look up before doing a chroot.
1445 On some systems, initializing the resolver library involves reading config files from
1446 /etc and/or loading additional shared libraries from /lib.
1447 On these systems, doing a hostname lookup before the chroot reduces
1448 the number of files that must be copied into the chroot tree.
1451 For fastest startup speed, a good value is a hostname that is not in /etc/hosts but that
1452 your local name server (listed in /etc/resolv.conf) can resolve without recursion
1453 (that is, without having to ask any other name servers). The hostname need not exist,
1454 but if it doesn't, an error message (which can be ignored) will be output.
1460 <emphasis>configfile</emphasis>
1463 If no <emphasis>configfile</emphasis> is included on the command line,
1464 <application>Privoxy</application> will look for a file named
1465 <quote>config</quote> in the current directory (except on Win32
1466 where it will look for <quote>config.txt</quote> instead). Specify
1467 full path to avoid confusion. If no config file is found,
1468 <application>Privoxy</application> will fail to start.
1475 On <application>MS Windows</application> only there are two additional
1476 command-line options to allow <application>Privoxy</application> to install and
1477 run as a <emphasis>service</emphasis>. See the
1478 <link linkend="installation-pack-win">Window Installation section</link>
1486 <!-- ~ End section ~ -->
1489 <!-- ~~~~~ New section ~~~~~ -->
1490 <sect1 id="configuration"><title>Privoxy Configuration</title>
1492 All <application>Privoxy</application> configuration is stored
1493 in text files. These files can be edited with a text editor.
1494 Many important aspects of <application>Privoxy</application> can
1495 also be controlled easily with a web browser.
1499 <!-- ~~~~~ New section ~~~~~ -->
1501 <sect2 id="control-with-webbrowser">
1502 <title>Controlling Privoxy with Your Web Browser</title>
1504 <application>Privoxy</application>'s user interface can be reached through the special
1505 URL <ulink url="http://config.privoxy.org/">http://config.privoxy.org/</ulink>
1506 (shortcut: <ulink url="http://p.p/">http://p.p/</ulink>),
1507 which is a built-in page and works without Internet access.
1508 You will see the following section:
1511 <!-- Needs to be put in a table and colorized -->
1512 <screen><!-- want the background color that goes with screen -->
1514 <bridgehead renderas="sect2"> Privoxy Menu</bridgehead>
1517 ▪ <ulink url="http://config.privoxy.org/show-status">View & change the current configuration</ulink>
1520 ▪ <ulink url="http://config.privoxy.org/client-tags">View or toggle the tags that can be set based on the clients address</ulink>
1523 ▪ <ulink url="http://config.privoxy.org/show-request">View the request headers.</ulink>
1526 ▪ <ulink url="http://config.privoxy.org/show-url-info">Look up which actions apply to a URL and why</ulink>
1529 ▪ <ulink url="http://config.privoxy.org/toggle">Toggle Privoxy on or off</ulink>
1532 ▪ <ulink
1533 url="https://www.privoxy.org/&p-version;/user-manual/">Documentation</ulink>
1541 This should be self-explanatory. Note the first item leads to an editor for the
1542 <link linkend="actions-file">actions files</link>, which is where the ad, banner,
1543 cookie, and URL blocking magic is configured as well as other advanced features of
1544 <application>Privoxy</application>. This is an easy way to adjust various
1545 aspects of <application>Privoxy</application> configuration. The actions
1546 file, and other configuration files, are explained in detail below.
1550 <quote>Toggle Privoxy On or Off</quote> is handy for sites that might
1551 have problems with your current actions and filters. You can in fact use
1552 it as a test to see whether it is <application>Privoxy</application>
1553 causing the problem or not. <application>Privoxy</application> continues
1554 to run as a proxy in this case, but all manipulation is disabled, i.e.
1555 <application>Privoxy</application> acts like a normal forwarding proxy.
1559 Note that several of the features described above are disabled by default
1560 in <application>Privoxy</application> 3.0.7 beta and later.
1562 <ulink url="config.html">configuration file</ulink> to learn why
1563 and in which cases it's safe to enable them again.
1568 <!-- ~ End section ~ -->
1573 <!-- ~~~~~ New section ~~~~~ -->
1575 <sect2 id="confoverview">
1576 <title>Configuration Files Overview</title>
1578 For Unix, *BSD and GNU/Linux, all configuration files are located in
1579 <filename>/etc/privoxy/</filename> by default. For MS Windows and OS/2
1580 these are all in the same directory as the
1581 <application>Privoxy</application> executable. <![%p-not-stable;[ The name
1582 and number of configuration files has changed from previous versions, and is
1583 subject to change as development progresses.]]>
1587 The installed defaults provide a reasonable starting point, though
1588 some settings may be aggressive by some standards. For the time being, the
1589 principle configuration files are:
1596 The <link linkend="config">main configuration file</link> is named <filename>config</filename>
1597 on GNU/Linux, Unix, BSD, and OS/2, and <filename>config.txt</filename>
1598 on Windows. This is a required file.
1604 <filename>match-all.action</filename> is used to define which <quote>actions</quote>
1605 relating to banner-blocking, images, pop-ups, content modification, cookie handling
1606 etc should be applied by default. It should be the first actions file loaded.
1609 <filename>default.action</filename> defines many exceptions (both positive and negative)
1610 from the default set of actions that's configured in <filename>match-all.action</filename>.
1611 It should be the second actions file loaded and shouldn't be edited by the user.
1614 Multiple actions files may be defined in <filename>config</filename>. These
1615 are processed in the order they are defined. Local customizations and locally
1616 preferred exceptions to the default policies as defined in
1617 <filename>match-all.action</filename> (which you will most probably want
1618 to define sooner or later) are best applied in <filename>user.action</filename>,
1619 where you can preserve them across upgrades. The file isn't installed by all
1620 installers, but you can easily create it yourself with a text editor.
1623 There is also a web based editor that can be accessed from
1625 url="http://config.privoxy.org/show-status">http://config.privoxy.org/show-status</ulink>
1627 url="http://p.p/show-status">http://p.p/show-status</ulink>) for the
1628 various actions files.
1634 <quote>Filter files</quote> (the <link linkend="filter-file">filter
1635 file</link>) can be used to re-write the raw page content, including
1636 viewable text as well as embedded HTML and JavaScript, and whatever else
1637 lurks on any given web page. The filtering jobs are only pre-defined here;
1638 whether to apply them or not is up to the actions files.
1639 <filename>default.filter</filename> includes various filters made
1640 available for use by the developers. Some are much more intrusive than
1641 others, and all should be used with caution. You may define additional
1642 filter files in <filename>config</filename> as you can with
1643 actions files. We suggest <filename>user.filter</filename> for any
1644 locally defined filters or customizations.
1651 The syntax of the configuration and filter files may change between different
1652 Privoxy versions, unfortunately some enhancements cost backwards compatibility.
1653 <!-- Add link to documentation-->
1657 All files use the <quote><literal>#</literal></quote> character to denote a
1658 comment (the rest of the line will be ignored) and understand line continuation
1659 through placing a backslash ("<literal>\</literal>") as the very last character
1660 in a line. If the <literal>#</literal> is preceded by a backslash, it looses
1661 its special function. Placing a <literal>#</literal> in front of an otherwise
1662 valid configuration line to prevent it from being interpreted is called "commenting
1663 out" that line. Blank lines are ignored.
1667 The actions files and filter files
1668 can use Perl style <link linkend="regex">regular expressions</link> for
1669 maximum flexibility.
1673 After making any changes, there is no need to restart
1674 <application>Privoxy</application> in order for the changes to take
1675 effect. <application>Privoxy</application> detects such changes
1676 automatically. Note, however, that it may take one or two additional
1677 requests for the change to take effect. When changing the listening address
1678 of <application>Privoxy</application>, these <quote>wake up</quote> requests
1679 must obviously be sent to the <emphasis>old</emphasis> listening address.
1684 While under development, the configuration content is subject to change.
1685 The below documentation may not be accurate by the time you read this.
1686 Also, what constitutes a <quote>default</quote> setting, may change, so
1687 please check all your configuration files on important issues.
1693 <!-- ~ End section ~ -->
1696 <!-- ~~~~~~~~ New section Header ~~~~~~~~~ -->
1698 <!-- **************************************************** -->
1699 <!-- Include config.sgml here -->
1700 <!-- This is where the entire config file is detailed. -->
1702 <!-- end include -->
1705 <!-- ~ End section ~ -->
1709 <!-- ~~~~~~~~ New section Header ~~~~~~~~~ -->
1711 <sect1 id="actions-file"><title>Actions Files</title>
1715 XXX: similar descriptions are in the Configuration Files sections.
1716 We should only describe them at one place.
1719 The actions files are used to define what <emphasis>actions</emphasis>
1720 <application>Privoxy</application> takes for which URLs, and thus determines
1721 how ad images, cookies and various other aspects of HTTP content and
1722 transactions are handled, and on which sites (or even parts thereof).
1723 There are a number of such actions, with a wide range of functionality.
1724 Each action does something a little different.
1725 These actions give us a veritable arsenal of tools with which to exert
1726 our control, preferences and independence. Actions can be combined so that
1727 their effects are aggregated when applied against a given set of URLs.
1731 are three action files included with <application>Privoxy</application> with
1737 <filename>match-all.action</filename> - is used to define which
1738 <quote>actions</quote> relating to banner-blocking, images, pop-ups,
1739 content modification, cookie handling etc should be applied by default.
1740 It should be the first actions file loaded
1745 <filename>default.action</filename> - defines many exceptions (both
1746 positive and negative) from the default set of actions that's configured
1747 in <filename>match-all.action</filename>. It is a set of rules that should
1748 work reasonably well as-is for most users. This file is only supposed to
1749 be edited by the developers. It should be the second actions file loaded.
1754 <filename>user.action</filename> - is intended to be for local site
1755 preferences and exceptions. As an example, if your ISP or your bank
1756 has specific requirements, and need special handling, this kind of
1757 thing should go here. This file will not be upgraded.
1762 <guibutton>Edit</guibutton> <guibutton>Set to Cautious</guibutton> <guibutton>Set to Medium</guibutton> <guibutton>Set to Advanced</guibutton>
1765 These have increasing levels of aggressiveness <emphasis>and have no
1766 influence on your browsing unless you select them explicitly in the
1767 editor</emphasis>. A default installation should be pre-set to
1768 <literal>Cautious</literal>. New users should try this for a while before
1769 adjusting the settings to more aggressive levels. The more aggressive
1770 the settings, then the more likelihood there is of problems such as sites
1771 not working as they should.
1774 The <guibutton>Edit</guibutton> button allows you to turn each
1775 action on/off individually for fine-tuning. The <guibutton>Cautious</guibutton>
1776 button changes the actions list to low/safe settings which will activate
1777 ad blocking and a minimal set of &my-app;'s features, and subsequently
1778 there will be less of a chance for accidental problems. The
1779 <guibutton>Medium</guibutton> button sets the list to a medium level of
1780 other features and a low level set of privacy features. The
1781 <guibutton>Advanced</guibutton> button sets the list to a high level of
1782 ad blocking and medium level of privacy. See the chart below. The latter
1783 three buttons over-ride any changes via with the
1784 <guibutton>Edit</guibutton> button. More fine-tuning can be done in the
1785 lower sections of this internal page.
1788 While the actions file editor allows to enable these settings in all
1789 actions files, they are only supposed to be enabled in the first one
1790 to make sure you don't unintentionally overrule earlier rules.
1793 The default profiles, and their associated actions, as pre-defined in
1794 <filename>default.action</filename> are:
1796 <table frame=all><title>Default Configurations</title>
1797 <tgroup cols=4 align=left colsep=1 rowsep=1>
1798 <colspec colname=c1>
1799 <colspec colname=c2>
1800 <colspec colname=c3>
1801 <colspec colname=c4>
1804 <entry>Feature</entry>
1805 <entry>Cautious</entry>
1806 <entry>Medium</entry>
1807 <entry>Advanced</entry>
1812 <!-- <entry>f1</entry> -->
1813 <!-- <entry>f2</entry> -->
1814 <!-- <entry>f3</entry> -->
1815 <!-- <entry>f4</entry> -->
1821 <entry>Ad-blocking Aggressiveness</entry>
1822 <entry>medium</entry>
1828 <entry>Ad-filtering by size</entry>
1835 <entry>Ad-filtering by link</entry>
1841 <entry>Pop-up killing</entry>
1842 <entry>blocks only</entry>
1843 <entry>blocks only</entry>
1844 <entry>blocks only</entry>
1848 <entry>Privacy Features</entry>
1850 <entry>medium</entry>
1851 <entry>medium/high</entry>
1855 <entry>Cookie handling</entry>
1857 <entry>session-only</entry>
1862 <entry>Referer forging</entry>
1869 <entry>GIF de-animation</entry>
1876 <entry>Fast redirects</entry>
1883 <entry>HTML taming</entry>
1890 <entry>JavaScript taming</entry>
1897 <entry>Web-bug killing</entry>
1904 <entry>Image tag reordering</entry>
1918 The list of actions files to be used are defined in the main configuration
1919 file, and are processed in the order they are defined (e.g.
1920 <filename>default.action</filename> is typically processed before
1921 <filename>user.action</filename>). The content of these can all be viewed and
1923 url="http://config.privoxy.org/show-status">http://config.privoxy.org/show-status</ulink>.
1924 The over-riding principle when applying actions, is that the last action that
1925 matches a given URL wins. The broadest, most general rules go first
1926 (defined in <filename>default.action</filename>),
1927 followed by any exceptions (typically also in
1928 <filename>default.action</filename>), which are then followed lastly by any
1929 local preferences (typically in <emphasis>user</emphasis><filename>.action</filename>).
1930 Generally, <filename>user.action</filename> has the last word.
1934 An actions file typically has multiple sections. If you want to use
1935 <quote>aliases</quote> in an actions file, you have to place the (optional)
1936 <link linkend="aliases">alias section</link> at the top of that file.
1937 Then comes the default set of rules which will apply universally to all
1938 sites and pages (be <emphasis>very careful</emphasis> with using such a
1939 universal set in <filename>user.action</filename> or any other actions file after
1940 <filename>default.action</filename>, because it will override the result
1941 from consulting any previous file). And then below that,
1942 exceptions to the defined universal policies. You can regard
1943 <filename>user.action</filename> as an appendix to <filename>default.action</filename>,
1944 with the advantage that it is a separate file, which makes preserving your
1945 personal settings across <application>Privoxy</application> upgrades easier.
1949 Actions can be used to block anything you want, including ads, banners, or
1950 just some obnoxious URL whose content you would rather not see. Cookies can be accepted
1951 or rejected, or accepted only during the current browser session (i.e. not
1952 written to disk), content can be modified, some JavaScripts tamed, user-tracking
1953 fooled, and much more. See below for a <link linkend="actions">complete list
1957 <!-- ~~~~~ New section ~~~~~ -->
1958 <sect2 id="right-mix">
1959 <title>Finding the Right Mix</title>
1961 Note that some <link linkend="actions">actions</link>, like cookie suppression
1962 or script disabling, may render some sites unusable that rely on these
1963 techniques to work properly. Finding the right mix of actions is not always easy and
1964 certainly a matter of personal taste. And, things can always change, requiring
1965 refinements in the configuration. In general, it can be said that the more
1966 <quote>aggressive</quote> your default settings (in the top section of the
1967 actions file) are, the more exceptions for <quote>trusted</quote> sites you
1968 will have to make later. If, for example, you want to crunch all cookies per
1969 default, you'll have to make exceptions from that rule for sites that you
1970 regularly use and that require cookies for actually useful purposes, like maybe
1971 your bank, favorite shop, or newspaper.
1975 We have tried to provide you with reasonable rules to start from in the
1976 distribution actions files. But there is no general rule of thumb on these
1977 things. There just are too many variables, and sites are constantly changing.
1978 Sooner or later you will want to change the rules (and read this chapter again :).
1982 <!-- ~~~~~ New section ~~~~~ -->
1983 <sect2 id="how-to-edit">
1984 <title>How to Edit</title>
1986 The easiest way to edit the actions files is with a browser by
1987 using our browser-based editor, which can be reached from <ulink
1988 url="http://config.privoxy.org/show-status">http://config.privoxy.org/show-status</ulink>.
1989 Note: the config file option <link
1990 linkend="enable-edit-actions">enable-edit-actions</link> must be enabled for
1991 this to work. The editor allows both fine-grained control over every single
1992 feature on a per-URL basis, and easy choosing from wholesale sets of defaults
1993 like <quote>Cautious</quote>, <quote>Medium</quote> or
1994 <quote>Advanced</quote>. Warning: the <quote>Advanced</quote> setting is more
1995 aggressive, and will be more likely to cause problems for some sites.
1996 Experienced users only!
2000 If you prefer plain text editing to GUIs, you can of course also directly edit the
2001 the actions files with your favorite text editor. Look at
2002 <filename>default.action</filename> which is richly commented with many
2008 <sect2 id="actions-apply">
2009 <title>How Actions are Applied to Requests</title>
2011 Actions files are divided into sections. There are special sections,
2012 like the <quote><link linkend="aliases">alias</link></quote> sections which will
2013 be discussed later. For now let's concentrate on regular sections: They have a
2014 heading line (often split up to multiple lines for readability) which consist
2015 of a list of actions, separated by whitespace and enclosed in curly braces.
2016 Below that, there is a list of URL and tag patterns, each on a separate line.
2020 To determine which actions apply to a request, the URL of the request is
2021 compared to all URL patterns in each <quote>action file</quote>.
2022 Every time it matches, the list of applicable actions for the request is
2023 incrementally updated, using the heading of the section in which the
2024 pattern is located. The same is done again for tags and tag patterns later on.
2028 If multiple applying sections set the same action differently,
2029 the last match wins. If not, the effects are aggregated.
2030 E.g. a URL might match a regular section with a heading line of <literal>{
2031 +<link linkend="handle-as-image">handle-as-image</link> }</literal>,
2032 then later another one with just <literal>{
2033 +<link linkend="block">block</link> }</literal>, resulting
2034 in <emphasis>both</emphasis> actions to apply. And there may well be
2035 cases where you will want to combine actions together. Such a section then
2040 { +<literal>handle-as-image</literal> +<literal>block{Banner ads.}</literal> }
2041 # Block these as if they were images. Send no block page.
2043 media.example.com/.*banners
2044 .example.com/images/ads/</screen>
2047 You can trace this process for URL patterns and any given URL by visiting <ulink
2048 url="http://config.privoxy.org/show-url-info">http://config.privoxy.org/show-url-info</ulink>.
2052 Examples and more detail on this is provided in the Appendix, <link linkend="ACTIONSANAT">
2053 Troubleshooting: Anatomy of an Action</link> section.
2057 <!-- ~~~~~ New section ~~~~~ -->
2058 <sect2 id="af-patterns">
2059 <title>Patterns</title>
2061 As mentioned, <application>Privoxy</application> uses <quote>patterns</quote>
2062 to determine what <emphasis>actions</emphasis> might apply to which sites and
2063 pages your browser attempts to access. These <quote>patterns</quote> use wild
2064 card type <emphasis>pattern</emphasis> matching to achieve a high degree of
2065 flexibility. This allows one expression to be expanded and potentially match
2066 against many similar patterns.
2070 Generally, an URL pattern has the form
2071 <literal><host><port>/<path></literal>, where the
2072 <literal><host></literal>, the <literal><port></literal>
2073 and the <literal><path></literal> are optional. (This is why the special
2074 <literal>/</literal> pattern matches all URLs). Note that the protocol
2075 portion of the URL pattern (e.g. <literal>http://</literal>) should
2076 <emphasis>not</emphasis> be included in the pattern. This is assumed already!
2079 The pattern matching syntax is different for the host and path parts of
2080 the URL. The host part uses a simple globbing type matching technique,
2081 while the path part uses more flexible
2082 <ulink url="http://en.wikipedia.org/wiki/Regular_expressions"><quote>Regular
2083 Expressions</quote></ulink> (POSIX 1003.2).
2086 The port part of a pattern is a decimal port number preceded by a colon
2087 (<literal>:</literal>). If the host part contains a numerical IPv6 address,
2088 it has to be put into angle brackets
2089 (<literal><</literal>, <literal>></literal>).
2094 <term><literal>www.example.com/</literal></term>
2097 is a host-only pattern and will match any request to <literal>www.example.com</literal>,
2098 regardless of which document on that server is requested. So ALL pages in
2099 this domain would be covered by the scope of this action. Note that a
2100 simple <literal>example.com</literal> is different and would NOT match.
2105 <term><literal>www.example.com</literal></term>
2108 means exactly the same. For host-only patterns, the trailing <literal>/</literal> may
2114 <term><literal>www.example.com/index.html</literal></term>
2117 matches all the documents on <literal>www.example.com</literal>
2118 whose name starts with <literal>/index.html</literal>.
2123 <term><literal>www.example.com/index.html$</literal></term>
2126 matches only the single document <literal>/index.html</literal>
2127 on <literal>www.example.com</literal>.
2132 <term><literal>/index.html$</literal></term>
2135 matches the document <literal>/index.html</literal>, regardless of the domain,
2136 i.e. on <emphasis>any</emphasis> web server anywhere.
2141 <term><literal>/</literal></term>
2144 Matches any URL because there's no requirement for either the
2145 domain or the path to match anything.
2150 <term><literal>:8000/</literal></term>
2153 Matches any URL pointing to TCP port 8000.
2158 <term><literal>10.0.0.1/</literal></term>
2161 Matches any URL with the host address <literal>10.0.0.1</literal>.
2162 (Note that the real URL uses plain brackets, not angle brackets.)
2167 <term><literal><2001:db8::1>/</literal></term>
2170 Matches any URL with the host address <literal>2001:db8::1</literal>.
2171 (Note that the real URL uses plain brackets, not angle brackets.)
2176 <term><literal>index.html</literal></term>
2179 matches nothing, since it would be interpreted as a domain name and
2180 there is no top-level domain called <literal>.html</literal>. So its
2188 <!-- ~~~~~ New section ~~~~~ -->
2189 <sect3 id="host-pattern"><title>The Host Pattern</title>
2192 The matching of the host part offers some flexible options: if the
2193 host pattern starts or ends with a dot, it becomes unanchored at that end.
2194 The host pattern is often referred to as domain pattern as it is usually
2195 used to match domain names and not IP addresses.
2201 <term><literal>.example.com</literal></term>
2204 matches any domain with first-level domain <literal>com</literal>
2205 and second-level domain <literal>example</literal>.
2206 For example <literal>www.example.com</literal>,
2207 <literal>example.com</literal> and <literal>foo.bar.baz.example.com</literal>.
2208 Note that it wouldn't match if the second-level domain was <literal>another-example</literal>.
2213 <term><literal>www.</literal></term>
2216 matches any domain that <emphasis>STARTS</emphasis> with
2217 <literal>www.</literal> (It also matches the domain
2218 <literal>www</literal> but most of the time that doesn't matter.)
2223 <term><literal>.example.</literal></term>
2226 matches any domain that <emphasis>CONTAINS</emphasis> <literal>.example.</literal>.
2227 And, by the way, also included would be any files or documents that exist
2228 within that domain since no path limitations are specified. (Correctly
2229 speaking: It matches any FQDN that contains <literal>example</literal> as
2230 a domain.) This might be <literal>www.example.com</literal>,
2231 <literal>news.example.de</literal>, or
2232 <literal>www.example.net/cgi/testing.pl</literal> for instance. All these
2240 Additionally, there are wild-cards that you can use in the domain names
2241 themselves. These work similarly to shell globbing type wild-cards:
2242 <quote>*</quote> represents zero or more arbitrary characters (this is
2244 <ulink url="http://en.wikipedia.org/wiki/Regular_expressions"><quote>Regular
2245 Expression</quote></ulink> based syntax of <quote>.*</quote>),
2246 <quote>?</quote> represents any single character (this is equivalent to the
2247 regular expression syntax of a simple <quote>.</quote>), and you can define
2248 <quote>character classes</quote> in square brackets which is similar to
2249 the same regular expression technique. All of this can be freely mixed:
2254 <term><literal>ad*.example.com</literal></term>
2257 matches <quote>adserver.example.com</quote>,
2258 <quote>ads.example.com</quote>, etc but not <quote>sfads.example.com</quote>
2263 <term><literal>*ad*.example.com</literal></term>
2266 matches all of the above, and then some.
2271 <term><literal>.?pix.com</literal></term>
2274 matches <literal>www.ipix.com</literal>,
2275 <literal>pictures.epix.com</literal>, <literal>a.b.c.d.e.upix.com</literal> etc.
2280 <term><literal>www[1-9a-ez].example.c*</literal></term>
2283 matches <literal>www1.example.com</literal>,
2284 <literal>www4.example.cc</literal>, <literal>wwwd.example.cy</literal>,
2285 <literal>wwwz.example.com</literal> etc., but <emphasis>not</emphasis>
2286 <literal>wwww.example.com</literal>.
2293 While flexible, this is not the sophistication of full regular expression based syntax.
2298 <!-- ~ End section ~ -->
2301 <!-- ~~~~~ New section ~~~~~ -->
2302 <sect3 id="path-pattern"><title>The Path Pattern</title>
2305 <application>Privoxy</application> uses <quote>modern</quote> POSIX 1003.2
2306 <ulink url="http://en.wikipedia.org/wiki/Regular_expressions"><quote>Regular
2307 Expressions</quote></ulink> for matching the path portion (after the slash),
2308 and is thus more flexible.
2312 There is an <link linkend="regex">Appendix</link> with a brief quick-start into regular
2313 expressions, you also might want to have a look at your operating system's documentation
2314 on regular expressions (try <literal>man re_format</literal>).
2318 Note that the path pattern is automatically left-anchored at the <quote>/</quote>,
2319 i.e. it matches as if it would start with a <quote>^</quote> (regular expression speak
2320 for the beginning of a line).
2324 Please also note that matching in the path is <emphasis>CASE INSENSITIVE</emphasis>
2325 by default, but you can switch to case sensitive at any point in the pattern by using the
2326 <quote>(?-i)</quote> switch: <literal>www.example.com/(?-i)PaTtErN.*</literal> will match
2327 only documents whose path starts with <literal>PaTtErN</literal> in
2328 <emphasis>exactly</emphasis> this capitalization.
2333 <term><literal>.example.com/.*</literal></term>
2336 Is equivalent to just <quote>.example.com</quote>, since any documents
2337 within that domain are matched with or without the <quote>.*</quote>
2338 regular expression. This is redundant
2343 <term><literal>.example.com/.*/index.html$</literal></term>
2346 Will match any page in the domain of <quote>example.com</quote> that is
2347 named <quote>index.html</quote>, and that is part of some path. For
2348 example, it matches <quote>www.example.com/testing/index.html</quote> but
2349 NOT <quote>www.example.com/index.html</quote> because the regular
2350 expression called for at least two <quote>/'s</quote>, thus the path
2351 requirement. It also would match
2352 <quote>www.example.com/testing/index_html</quote>, because of the
2353 special meta-character <quote>.</quote>.
2358 <term><literal>.example.com/(.*/)?index\.html$</literal></term>
2361 This regular expression is conditional so it will match any page
2362 named <quote>index.html</quote> regardless of path which in this case can
2363 have one or more <quote>/'s</quote>. And this one must contain exactly
2364 <quote>.html</quote> (and end with that!).
2369 <term><literal>.example.com/(.*/)(ads|banners?|junk)</literal></term>
2372 This regular expression will match any path of <quote>example.com</quote>
2373 that contains any of the words <quote>ads</quote>, <quote>banner</quote>,
2374 <quote>banners</quote> (because of the <quote>?</quote>) or <quote>junk</quote>.
2375 The path does not have to end in these words, just contain them.
2376 The path has to contain at least two slashes (including the one at the beginning).
2381 <term><literal>.example.com/(.*/)(ads|banners?|junk)/.*\.(jpe?g|gif|png)$</literal></term>
2384 This is very much the same as above, except now it must end in either
2385 <quote>.jpg</quote>, <quote>.jpeg</quote>, <quote>.gif</quote> or <quote>.png</quote>. So this
2386 one is limited to common image formats.
2393 There are many, many good examples to be found in <filename>default.action</filename>,
2394 and more tutorials below in <link linkend="regex">Appendix on regular expressions</link>.
2399 <!-- ~ End section ~ -->
2402 <!-- ~~~~~ New section ~~~~~ -->
2403 <sect3 id="tag-pattern"><title>The Request Tag Pattern</title>
2406 Request tag patterns are used to change the applying actions based on the
2407 request's tags. Tags can be created based on HTTP headers with either
2408 the <link linkend="CLIENT-HEADER-TAGGER">client-header-tagger</link>
2409 or the <link linkend="SERVER-HEADER-TAGGER">server-header-tagger</link> action.
2413 Request tag patterns have to start with <quote>TAG:</quote>, so &my-app;
2414 can tell them apart from other patterns. Everything after the colon
2415 including white space, is interpreted as a regular expression with
2416 path pattern syntax, except that tag patterns aren't left-anchored
2417 automatically (&my-app; doesn't silently add a <quote>^</quote>,
2418 you have to do it yourself if you need it).
2422 To match all requests that are tagged with <quote>foo</quote>
2423 your pattern line should be <quote>TAG:^foo$</quote>,
2424 <quote>TAG:foo</quote> would work as well, but it would also
2425 match requests whose tags contain <quote>foo</quote> somewhere.
2426 <quote>TAG: foo</quote> wouldn't work as it requires white space.
2430 Sections can contain URL and request tag patterns at the same time,
2431 but request tag patterns are checked after the URL patterns and thus
2432 always overrule them, even if they are located before the URL patterns.
2436 Once a new request tag is added, Privoxy checks right away if it's matched by one
2437 of the request tag patterns and updates the action settings accordingly. As a result
2438 request tags can be used to activate other tagger actions, as long as these other
2439 taggers look for headers that haven't already be parsed.
2443 For example you could tag client requests which use the
2444 <literal>POST</literal> method,
2445 then use this tag to activate another tagger that adds a tag if cookies
2446 are sent, and then use a block action based on the cookie tag. This allows
2447 the outcome of one action, to be input into a subsequent action. However if
2448 you'd reverse the position of the described taggers, and activated the
2449 method tagger based on the cookie tagger, no method tags would be created.
2450 The method tagger would look for the request line, but at the time
2451 the cookie tag is created, the request line has already been parsed.
2455 While this is a limitation you should be aware of, this kind of
2456 indirection is seldom needed anyway and even the example doesn't
2457 make too much sense.
2462 <!-- ~~~~~ New section ~~~~~ -->
2463 <sect3 id="negative-tag-patterns"><title>The Negative Request Tag Patterns</title>
2466 To match requests that do not have a certain request tag, specify a negative tag pattern
2467 by prefixing the tag pattern line with either <quote>NO-REQUEST-TAG:</quote>
2468 or <quote>NO-RESPONSE-TAG:</quote> instead of <quote>TAG:</quote>.
2472 Negative request tag patterns created with <quote>NO-REQUEST-TAG:</quote> are checked
2473 after all client headers are scanned, the ones created with <quote>NO-RESPONSE-TAG:</quote>
2474 are checked after all server headers are scanned. In both cases all the created
2475 tags are considered.
2479 <!-- ~~~~~ New section ~~~~~ -->
2480 <sect3 id="client-tag-pattern"><title>The Client Tag Pattern</title>
2482 <!-- XXX: This section contains duplicates content from the
2483 client-specific-tag documentation. -->
2487 This is an experimental feature. The syntax is likely to change in future versions.
2492 Client tag patterns are not set based on HTTP headers but based on
2493 the client's IP address. Users can enable them themselves, but the
2494 Privoxy admin controls which tags are available and what their effect
2499 After a client-specific tag has been defined with the
2500 <link linkend="client-specific-tag">client-specific-tag</link>,
2501 directive, action sections can be activated based on the tag by using a
2502 CLIENT-TAG pattern. The CLIENT-TAG pattern is evaluated at the same priority
2503 as URL patterns, as a result the last matching pattern wins. Tags that
2504 are created based on client or server headers are evaluated later on
2505 and can overrule CLIENT-TAG and URL patterns!
2508 The tag is set for all requests that come from clients that requested
2509 it to be set. Note that "clients" are differentiated by IP address,
2510 if the IP address changes the tag has to be requested again.
2513 Clients can request tags to be set by using the CGI interface <ulink
2514 url="http://config.privoxy.org/client-tags">http://config.privoxy.org/client-tags</ulink>.
2522 # If the admin defined the client-specific-tag circumvent-blocks,
2523 # and the request comes from a client that previously requested
2524 # the tag to be set, overrule all previous +block actions that
2525 # are enabled based on URL to CLIENT-TAG patterns.
2527 CLIENT-TAG:^circumvent-blocks$
2529 # This section is not overruled because it's located after
2531 {+block{Nobody is supposed to request this.}}
2532 example.org/blocked-example-page</screen>
2538 <!-- ~ End section ~ -->
2541 <!-- ~~~~~ New section ~~~~~ -->
2543 <sect2 id="actions">
2544 <title>Actions</title>
2546 All actions are disabled by default, until they are explicitly enabled
2547 somewhere in an actions file. Actions are turned on if preceded with a
2548 <quote>+</quote>, and turned off if preceded with a <quote>-</quote>. So a
2549 <literal>+action</literal> means <quote>do that action</quote>, e.g.
2550 <literal>+block</literal> means <quote>please block URLs that match the
2551 following patterns</quote>, and <literal>-block</literal> means <quote>don't
2552 block URLs that match the following patterns, even if <literal>+block</literal>
2553 previously applied.</quote>
2557 Again, actions are invoked by placing them on a line, enclosed in curly braces and
2558 separated by whitespace, like in
2559 <literal>{+some-action -some-other-action{some-parameter}}</literal>,
2560 followed by a list of URL patterns, one per line, to which they apply.
2561 Together, the actions line and the following pattern lines make up a section
2562 of the actions file.
2566 Actions fall into three categories:
2572 Boolean, i.e the action can only be <quote>enabled</quote> or
2573 <quote>disabled</quote>. Syntax:
2576 +<replaceable class="function">name</replaceable> # enable action <replaceable class="parameter">name</replaceable>
2577 -<replaceable class="function">name</replaceable> # disable action <replaceable class="parameter">name</replaceable></screen>
2579 Example: <literal>+handle-as-image</literal>
2586 Parameterized, where some value is required in order to enable this type of action.
2590 +<replaceable class="function">name</replaceable>{<replaceable class="parameter">param</replaceable>} # enable action and set parameter to <replaceable class="parameter">param</replaceable>,
2591 # overwriting parameter from previous match if necessary
2592 -<replaceable class="function">name</replaceable> # disable action. The parameter can be omitted</screen>
2594 Note that if the URL matches multiple positive forms of a parameterized action,
2595 the last match wins, i.e. the params from earlier matches are simply ignored.
2598 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>
2604 Multi-value. These look exactly like parameterized actions,
2605 but they behave differently: If the action applies multiple times to the
2606 same URL, but with different parameters, <emphasis>all</emphasis> the parameters
2607 from <emphasis>all</emphasis> matches are remembered. This is used for actions
2608 that can be executed for the same request repeatedly, like adding multiple
2609 headers, or filtering through multiple filters. Syntax:
2612 +<replaceable class="function">name</replaceable>{<replaceable class="parameter">param</replaceable>} # enable action and add <replaceable class="parameter">param</replaceable> to the list of parameters
2613 -<replaceable class="function">name</replaceable>{<replaceable class="parameter">param</replaceable>} # remove the parameter <replaceable class="parameter">param</replaceable> from the list of parameters
2614 # If it was the last one left, disable the action.
2615 <replaceable class="parameter">-name</replaceable> # disable this action completely and remove all parameters from the list</screen>
2617 Examples: <literal>+add-header{X-Fun-Header: Some text}</literal> and
2618 <literal>+filter{html-annoyances}</literal>
2625 If nothing is specified in any actions file, no <quote>actions</quote> are
2626 taken. So in this case <application>Privoxy</application> would just be a
2627 normal, non-blocking, non-filtering proxy. You must specifically enable the
2628 privacy and blocking features you need (although the provided default actions
2629 files will give a good starting point).
2633 Later defined action sections always over-ride earlier ones of the same type.
2634 So exceptions to any rules you make, should come in the latter part of the file (or
2635 in a file that is processed later when using multiple actions files such
2636 as <filename>user.action</filename>). For multi-valued actions, the actions
2637 are applied in the order they are specified. Actions files are processed in
2638 the order they are defined in <filename>config</filename> (the default
2639 installation has three actions files). It also quite possible for any given
2640 URL to match more than one <quote>pattern</quote> (because of wildcards and
2641 regular expressions), and thus to trigger more than one set of actions! Last
2645 <!-- start actions listing -->
2647 The list of valid <application>Privoxy</application> actions are:
2651 <!-- ********************************************************** -->
2652 <!-- Please note the below defined actions use id's that are -->
2653 <!-- probably linked from other places, so please don't change. -->
2655 <!-- ********************************************************** -->
2658 <!-- ~~~~~ New section ~~~~~ -->
2660 <sect3 renderas="sect4" id="add-header">
2661 <title>add-header</title>
2665 <term>Typical use:</term>
2667 <para>Confuse log analysis, custom applications</para>
2672 <term>Effect:</term>
2675 Sends a user defined HTTP header to the web server.
2682 <!-- boolean, parameterized, Multi-value -->
2684 <para>Multi-value.</para>
2689 <term>Parameter:</term>
2692 Any string value is possible. Validity of the defined HTTP headers is not checked.
2693 It is recommended that you use the <quote><literal>X-</literal></quote> prefix
2703 This action may be specified multiple times, in order to define multiple
2704 headers. This is rarely needed for the typical user. If you don't know what
2705 <quote>HTTP headers</quote> are, you definitely don't need to worry about this
2709 Headers added by this action are not modified by other actions.
2715 <term>Example usage:</term>
2717 <screen># Add a DNT ("Do not track") header to all requests,
2718 # event to those that already have one.
2720 # This is just an example, not a recommendation.
2722 # There is no reason to believe that user-tracking websites care
2723 # about the DNT header and depending on the User-Agent, adding the
2724 # header may make user-tracking easier.
2725 {+add-header{DNT: 1}}
2733 <!-- ~~~~~ New section ~~~~~ -->
2734 <sect3 renderas="sect4" id="block">
2735 <title>block</title>
2739 <term>Typical use:</term>
2741 <para>Block ads or other unwanted content</para>
2746 <term>Effect:</term>
2749 Requests for URLs to which this action applies are blocked, i.e. the
2750 requests are trapped by &my-app; and the requested URL is never retrieved,
2751 but is answered locally with a substitute page or image, as determined by
2753 linkend="handle-as-image">handle-as-image</link></literal>,
2755 linkend="set-image-blocker">set-image-blocker</link></literal>, and
2757 linkend="handle-as-empty-document">handle-as-empty-document</link></literal> actions.
2765 <!-- boolean, parameterized, Multi-value -->
2767 <para>Parameterized.</para>
2772 <term>Parameter:</term>
2774 <para>A block reason that should be given to the user.</para>
2782 <application>Privoxy</application> sends a special <quote>BLOCKED</quote> page
2783 for requests to blocked pages. This page contains the block reason given as
2784 parameter, a link to find out why the block action applies, and a click-through
2785 to the blocked content (the latter only if the force feature is available and
2789 A very important exception occurs if <emphasis>both</emphasis>
2790 <literal>block</literal> and <literal><link linkend="handle-as-image">handle-as-image</link></literal>,
2791 apply to the same request: it will then be replaced by an image. If
2792 <literal><link linkend="set-image-blocker">set-image-blocker</link></literal>
2793 (see below) also applies, the type of image will be determined by its parameter,
2794 if not, the standard checkerboard pattern is sent.
2797 It is important to understand this process, in order
2798 to understand how <application>Privoxy</application> deals with
2799 ads and other unwanted content. Blocking is a core feature, and one
2800 upon which various other features depend.
2803 The <literal><link linkend="filter">filter</link></literal>
2804 action can perform a very similar task, by <quote>blocking</quote>
2805 banner images and other content through rewriting the relevant URLs in the
2806 document's HTML source, so they don't get requested in the first place.
2807 Note that this is a totally different technique, and it's easy to confuse the two.
2813 <term>Example usage (section):</term>
2815 <screen>{+block{No nasty stuff for you.}}
2816 # Block and replace with "blocked" page
2817 .nasty-stuff.example.com
2819 {+block{Doubleclick banners.} +handle-as-image}
2820 # Block and replace with image
2824 {+block{Layered ads.} +handle-as-empty-document}
2825 # Block and then ignore
2826 adserver.example.net/.*\.js$</screen>
2835 <!-- ~~~~~ New section ~~~~~ -->
2836 <sect3 renderas="sect4" id="change-x-forwarded-for">
2837 <title>change-x-forwarded-for</title>
2841 <term>Typical use:</term>
2843 <para>Improve privacy by not forwarding the source of the request in the HTTP headers.</para>
2848 <term>Effect:</term>
2851 Deletes the <quote>X-Forwarded-For:</quote> HTTP header from the client request,
2859 <!-- Boolean, Parameterized, Multi-value -->
2861 <para>Parameterized.</para>
2866 <term>Parameter:</term>
2870 <para><quote>block</quote> to delete the header.</para>
2874 <quote>add</quote> to create the header (or append
2875 the client's IP address to an already existing one).
2886 It is safe and recommended to use <literal>block</literal>.
2889 Forwarding the source address of the request may make
2890 sense in some multi-user setups but is also a privacy risk.
2895 <term>Example usage:</term>
2897 <screen>+change-x-forwarded-for{block}</screen>
2903 <!-- ~~~~~ New section ~~~~~ -->
2904 <sect3 renderas="sect4" id="client-header-filter">
2905 <title>client-header-filter</title>
2909 <term>Typical use:</term>
2912 Rewrite or remove single client headers.
2918 <term>Effect:</term>
2921 All client headers to which this action applies are filtered on-the-fly through
2922 the specified regular expression based substitutions.
2929 <!-- boolean, parameterized, Multi-value -->
2931 <para>Multi-value.</para>
2936 <term>Parameter:</term>
2939 The name of a client-header filter, as defined in one of the
2940 <link linkend="filter-file">filter files</link>.
2949 Client-header filters are applied to each header on its own, not to
2950 all at once. This makes it easier to diagnose problems, but on the downside
2951 you can't write filters that only change header x if header y's value is z.
2952 You can do that by using tags though.
2955 Client-header filters are executed after the other header actions have finished
2956 and use their output as input.
2959 If the request URI gets changed, &my-app; will detect that and use the new
2960 one. This can be used to rewrite the request destination behind the client's
2961 back, for example to specify a Tor exit relay for certain requests.
2964 Please refer to the <link linkend="filter-file">filter file chapter</link>
2965 to learn which client-header filters are available by default, and how to
2973 <term>Example usage (section):</term>
2976 # Hide Tor exit notation in Host and Referer Headers
2977 {+client-header-filter{hide-tor-exit-notation}}
2987 <!-- ~~~~~ New section ~~~~~ -->
2988 <sect3 renderas="sect4" id="client-header-tagger">
2989 <title>client-header-tagger</title>
2993 <term>Typical use:</term>
2996 Block requests based on their headers.
3002 <term>Effect:</term>
3005 Client headers to which this action applies are filtered on-the-fly through
3006 the specified regular expression based substitutions, the result is used as
3014 <!-- boolean, parameterized, Multi-value -->
3016 <para>Multi-value.</para>
3021 <term>Parameter:</term>
3024 The name of a client-header tagger, as defined in one of the
3025 <link linkend="filter-file">filter files</link>.
3034 Client-header taggers are applied to each header on its own,
3035 and as the header isn't modified, each tagger <quote>sees</quote>
3039 Client-header taggers are the first actions that are executed
3040 and their tags can be used to control every other action.
3046 <term>Example usage (section):</term>
3049 # Tag every request with the User-Agent header
3050 {+client-header-tagger{user-agent}}
3053 # Tagging itself doesn't change the action
3054 # settings, sections with TAG patterns do:
3056 # If it's a download agent, use a different forwarding proxy,
3057 # show the real User-Agent and make sure resume works.
3058 {+forward-override{forward-socks5 10.0.0.2:2222 .} \
3059 -hide-if-modified-since \
3060 -overwrite-last-modified \
3065 TAG:^User-Agent: NetBSD-ftp/
3066 TAG:^User-Agent: Novell ZYPP Installer
3067 TAG:^User-Agent: RPM APT-HTTP/
3068 TAG:^User-Agent: fetch libfetch/
3069 TAG:^User-Agent: Ubuntu APT-HTTP/
3070 TAG:^User-Agent: MPlayer/
3074 # Tag all requests with the Range header set
3075 {+client-header-tagger{range-requests}}
3078 # Disable filtering for the tagged requests.
3080 # With filtering enabled Privoxy would remove the Range headers
3081 # to be able to filter the whole response. The downside is that
3082 # it prevents clients from resuming downloads or skipping over
3083 # parts of multimedia files.
3084 {-filter -deanimate-gifs}
3089 # Tag all requests with the client IP address
3091 # (Technically the client IP address isn't included in the
3092 # client headers but client-header taggers can set it anyway.
3093 # For details see the tagger in default.filter)
3094 {+client-header-tagger{client-ip-address}}
3097 # Change forwarding settings for requests coming from address 10.0.0.1
3098 {+forward-override{forward-socks5 127.0.1.2:2222 .}}
3099 TAG:^IP-ADDRESS: 10\.0\.0\.1$
3108 <!-- ~~~~~ New section ~~~~~ -->
3109 <sect3 renderas="sect4" id="content-type-overwrite">
3110 <title>content-type-overwrite</title>
3114 <term>Typical use:</term>
3116 <para>Stop useless download menus from popping up, or change the browser's rendering mode</para>
3121 <term>Effect:</term>
3124 Replaces the <quote>Content-Type:</quote> HTTP server header.
3131 <!-- Boolean, Parameterized, Multi-value -->
3133 <para>Parameterized.</para>
3138 <term>Parameter:</term>
3150 The <quote>Content-Type:</quote> HTTP server header is used by the
3151 browser to decide what to do with the document. The value of this
3152 header can cause the browser to open a download menu instead of
3153 displaying the document by itself, even if the document's format is
3154 supported by the browser.
3157 The declared content type can also affect which rendering mode
3158 the browser chooses. If XHTML is delivered as <quote>text/html</quote>,
3159 many browsers treat it as yet another broken HTML document.
3160 If it is send as <quote>application/xml</quote>, browsers with
3161 XHTML support will only display it, if the syntax is correct.
3164 If you see a web site that proudly uses XHTML buttons, but sets
3165 <quote>Content-Type: text/html</quote>, you can use &my-app;
3166 to overwrite it with <quote>application/xml</quote> and validate
3167 the web master's claim inside your XHTML-supporting browser.
3168 If the syntax is incorrect, the browser will complain loudly.
3171 You can also go the opposite direction: if your browser prints
3172 error messages instead of rendering a document falsely declared
3173 as XHTML, you can overwrite the content type with
3174 <quote>text/html</quote> and have it rendered as broken HTML document.
3177 By default <literal>content-type-overwrite</literal> only replaces
3178 <quote>Content-Type:</quote> headers that look like some kind of text.
3179 If you want to overwrite it unconditionally, you have to combine it with
3180 <literal><link linkend="force-text-mode">force-text-mode</link></literal>.
3181 This limitation exists for a reason, think twice before circumventing it.
3184 Most of the time it's easier to replace this action with a custom
3185 <literal><link linkend="server-header-filter">server-header filter</link></literal>.
3186 It allows you to activate it for every document of a certain site and it will still
3187 only replace the content types you aimed at.
3190 Of course you can apply <literal>content-type-overwrite</literal>
3191 to a whole site and then make URL based exceptions, but it's a lot
3192 more work to get the same precision.
3198 <term>Example usage (sections):</term>
3200 <screen># Check if www.example.net/ really uses valid XHTML
3201 { +content-type-overwrite{application/xml} }
3204 # but leave the content type unmodified if the URL looks like a style sheet
3205 {-content-type-overwrite}
3206 www.example.net/.*\.css$
3207 www.example.net/.*style
3215 <!-- ~~~~~ New section ~~~~~ -->
3216 <sect3 renderas="sect4" id="crunch-client-header">
3220 <title>crunch-client-header</title>
3224 <term>Typical use:</term>
3226 <para>Remove a client header <application>Privoxy</application> has no dedicated action for.</para>
3231 <term>Effect:</term>
3234 Deletes every header sent by the client that contains the string the user supplied as parameter.
3241 <!-- Boolean, Parameterized, Multi-value -->
3243 <para>Parameterized.</para>
3248 <term>Parameter:</term>
3260 This action allows you to block client headers for which no dedicated
3261 <application>Privoxy</application> action exists.
3262 <application>Privoxy</application> will remove every client header that
3263 contains the string you supplied as parameter.
3266 Regular expressions are <emphasis>not supported</emphasis> and you can't
3267 use this action to block different headers in the same request, unless
3268 they contain the same string.
3271 <literal>crunch-client-header</literal> is only meant for quick tests.
3272 If you have to block several different headers, or only want to modify
3273 parts of them, you should use a
3274 <literal><link linkend="client-header-filter">client-header filter</link></literal>.
3278 Don't block any header without understanding the consequences.
3285 <term>Example usage (section):</term>
3287 <screen># Block the non-existent "Privacy-Violation:" client header
3288 { +crunch-client-header{Privacy-Violation:} }
3297 <!-- ~~~~~ New section ~~~~~ -->
3298 <sect3 renderas="sect4" id="crunch-if-none-match">
3299 <title>crunch-if-none-match</title>
3305 <term>Typical use:</term>
3307 <para>Prevent yet another way to track the user's steps between sessions.</para>
3312 <term>Effect:</term>
3315 Deletes the <quote>If-None-Match:</quote> HTTP client header.
3322 <!-- Boolean, Parameterized, Multi-value -->
3324 <para>Boolean.</para>
3329 <term>Parameter:</term>
3341 Removing the <quote>If-None-Match:</quote> HTTP client header
3342 is useful for filter testing, where you want to force a real
3343 reload instead of getting status code <quote>304</quote> which
3344 would cause the browser to use a cached copy of the page.
3347 It is also useful to make sure the header isn't used as a cookie
3348 replacement (unlikely but possible).
3351 Blocking the <quote>If-None-Match:</quote> header shouldn't cause any
3352 caching problems, as long as the <quote>If-Modified-Since:</quote> header
3353 isn't blocked or missing as well.
3356 It is recommended to use this action together with
3357 <literal><link linkend="hide-if-modified-since">hide-if-modified-since</link></literal>
3359 <literal><link linkend="overwrite-last-modified">overwrite-last-modified</link></literal>.
3365 <term>Example usage (section):</term>
3367 <screen># Let the browser revalidate cached documents but don't
3368 # allow the server to use the revalidation headers for user tracking.
3369 {+hide-if-modified-since{-60} \
3370 +overwrite-last-modified{randomize} \
3371 +crunch-if-none-match}
3380 <!-- ~~~~~ New section ~~~~~ -->
3381 <sect3 renderas="sect4" id="crunch-incoming-cookies">
3382 <title>crunch-incoming-cookies</title>
3386 <term>Typical use:</term>
3389 Prevent the web server from setting HTTP cookies on your system
3395 <term>Effect:</term>
3398 Deletes any <quote>Set-Cookie:</quote> HTTP headers from server replies.
3405 <!-- Boolean, Parameterized, Multi-value -->
3407 <para>Boolean.</para>
3412 <term>Parameter:</term>
3424 This action is only concerned with <emphasis>incoming</emphasis> HTTP cookies. For
3425 <emphasis>outgoing</emphasis> HTTP cookies, use
3426 <literal><link linkend="crunch-outgoing-cookies">crunch-outgoing-cookies</link></literal>.
3427 Use <emphasis>both</emphasis> to disable HTTP cookies completely.
3430 It makes <emphasis>no sense at all</emphasis> to use this action in conjunction
3431 with the <literal><link linkend="session-cookies-only">session-cookies-only</link></literal> action,
3432 since it would prevent the session cookies from being set. See also
3433 <literal><link linkend="filter-content-cookies">filter-content-cookies</link></literal>.
3439 <term>Example usage:</term>
3441 <screen>+crunch-incoming-cookies</screen>
3448 <!-- ~~~~~ New section ~~~~~ -->
3449 <sect3 renderas="sect4" id="crunch-server-header">
3450 <title>crunch-server-header</title>
3456 <term>Typical use:</term>
3458 <para>Remove a server header <application>Privoxy</application> has no dedicated action for.</para>
3463 <term>Effect:</term>
3466 Deletes every header sent by the server that contains the string the user supplied as parameter.
3473 <!-- Boolean, Parameterized, Multi-value -->
3475 <para>Parameterized.</para>
3480 <term>Parameter:</term>
3492 This action allows you to block server headers for which no dedicated
3493 <application>Privoxy</application> action exists. <application>Privoxy</application>
3494 will remove every server header that contains the string you supplied as parameter.
3497 Regular expressions are <emphasis>not supported</emphasis> and you can't
3498 use this action to block different headers in the same request, unless
3499 they contain the same string.
3502 <literal>crunch-server-header</literal> is only meant for quick tests.
3503 If you have to block several different headers, or only want to modify
3504 parts of them, you should use a custom
3505 <literal><link linkend="server-header-filter">server-header filter</link></literal>.
3509 Don't block any header without understanding the consequences.
3516 <term>Example usage (section):</term>
3518 <screen># Crunch server headers that try to prevent caching
3519 { +crunch-server-header{no-cache} }
3528 <!-- ~~~~~ New section ~~~~~ -->
3529 <sect3 renderas="sect4" id="crunch-outgoing-cookies">
3530 <title>crunch-outgoing-cookies</title>
3534 <term>Typical use:</term>
3537 Prevent the web server from reading any HTTP cookies from your system
3543 <term>Effect:</term>
3546 Deletes any <quote>Cookie:</quote> HTTP headers from client requests.
3553 <!-- Boolean, Parameterized, Multi-value -->
3555 <para>Boolean.</para>
3560 <term>Parameter:</term>
3572 This action is only concerned with <emphasis>outgoing</emphasis> HTTP cookies. For
3573 <emphasis>incoming</emphasis> HTTP cookies, use
3574 <literal><link linkend="crunch-incoming-cookies">crunch-incoming-cookies</link></literal>.
3575 Use <emphasis>both</emphasis> to disable HTTP cookies completely.
3578 It makes <emphasis>no sense at all</emphasis> to use this action in conjunction
3579 with the <literal><link linkend="session-cookies-only">session-cookies-only</link></literal> action,
3580 since it would prevent the session cookies from being read.
3586 <term>Example usage:</term>
3588 <screen>+crunch-outgoing-cookies</screen>
3596 <!-- ~~~~~ New section ~~~~~ -->
3597 <sect3 renderas="sect4" id="deanimate-gifs">
3598 <title>deanimate-gifs</title>
3602 <term>Typical use:</term>
3604 <para>Stop those annoying, distracting animated GIF images.</para>
3609 <term>Effect:</term>
3612 De-animate GIF animations, i.e. reduce them to their first or last image.
3619 <!-- boolean, parameterized, Multi-value -->
3621 <para>Parameterized.</para>
3626 <term>Parameter:</term>
3629 <quote>last</quote> or <quote>first</quote>
3638 This will also shrink the images considerably (in bytes, not pixels!). If
3639 the option <quote>first</quote> is given, the first frame of the animation
3640 is used as the replacement. If <quote>last</quote> is given, the last
3641 frame of the animation is used instead, which probably makes more sense for
3642 most banner animations, but also has the risk of not showing the entire
3643 last frame (if it is only a delta to an earlier frame).
3646 You can safely use this action with patterns that will also match non-GIF
3647 objects, because no attempt will be made at anything that doesn't look like
3654 <term>Example usage:</term>
3656 <screen>+deanimate-gifs{last}</screen>
3663 <!-- ~~~~~ New section ~~~~~ -->
3664 <sect3 renderas="sect4" id="delay-response">
3665 <title>delay-response</title>
3669 <term>Typical use:</term>
3671 <para>Delay responses to the client to reduce the load</para>
3676 <term>Effect:</term>
3679 Delays responses to the client by sending the response in ca. 10 byte chunks.
3686 <!-- boolean, parameterized, Multi-value -->
3688 <para>Parameterized.</para>
3693 <term>Parameter:</term>
3696 <quote>Number of milliseconds</quote>
3705 Sometimes when JavaScript code is used to fetch advertisements
3706 it doesn't respect Privoxy's blocks and retries to fetch the
3707 same resource again causing unnecessary load on the client.
3710 This action delays responses to the client and can be combined
3711 with <literal><link linkend="block">blocks</link></literal>
3712 to slow down the JavaScript code, thus reducing
3713 the load on the client.
3716 When used without <literal><link linkend="block">blocks</link></literal>
3717 the action can also be used to simulate a slow internet connection.
3723 <term>Example usage:</term>
3725 <screen>+delay-response{100}</screen>
3732 <!-- ~~~~~ New section ~~~~~ -->
3733 <sect3 renderas="sect4" id="downgrade-http-version">
3734 <title>downgrade-http-version</title>
3738 <term>Typical use:</term>
3740 <para>Work around (very rare) problems with HTTP/1.1</para>
3745 <term>Effect:</term>
3748 Downgrades HTTP/1.1 client requests and server replies to HTTP/1.0.
3755 <!-- boolean, parameterized, Multi-value -->
3757 <para>Boolean.</para>
3762 <term>Parameter:</term>
3774 This is a left-over from the time when <application>Privoxy</application>
3775 didn't support important HTTP/1.1 features well. It is left here for the
3776 unlikely case that you experience HTTP/1.1-related problems with some server
3780 Note that enabling this action is only a workaround. It should not
3781 be enabled for sites that work without it. While it shouldn't break
3782 any pages, it has an (usually negative) performance impact.
3785 If you come across a site where enabling this action helps, please report it,
3786 so the cause of the problem can be analyzed. If the problem turns out to be
3787 caused by a bug in <application>Privoxy</application> it should be
3788 fixed so the following release works without the work around.
3794 <term>Example usage (section):</term>
3796 <screen>{+downgrade-http-version}
3797 problem-host.example.com</screen>
3805 <!-- ~~~~~ New section ~~~~~ -->
3806 <sect3 renderas="sect4" id="external-filter">
3807 <title>external-filter</title>
3811 <term>Typical use:</term>
3813 <para>Modify content using a programming language of your choice.</para>
3818 <term>Effect:</term>
3821 All instances of text-based type, most notably HTML and JavaScript, to which
3822 this action applies, can be filtered on-the-fly through the specified external
3824 By default plain text documents are exempted from filtering, because web
3825 servers often use the <literal>text/plain</literal> MIME type for all files
3826 whose type they don't know.)
3833 <!-- boolean, parameterized, Multi-value -->
3835 <para>Multi-value.</para>
3840 <term>Parameter:</term>
3843 The name of an external content filter, as defined in the
3844 <link linkend="filter-file">filter file</link>.
3845 External filters can be defined in one or more files as defined by the
3846 <literal><link linkend="filterfile">filterfile</link></literal>
3847 option in the <link linkend="config">config file</link>.
3850 When used in its negative form,
3851 and without parameters, <emphasis>all</emphasis> filtering with external
3852 filters is completely disabled.
3861 External filters are scripts or programs that can modify the content in
3862 case common <literal><link linkend="filter">filters</link></literal>
3863 aren't powerful enough. With the exception that this action doesn't
3864 use pcrs-based filters, the notes in the
3865 <literal><link linkend="filter">filter</link></literal> section apply.
3869 Currently external filters are executed with &my-app;'s privileges.
3870 Only use external filters you understand and trust.
3874 This feature is experimental, the <literal><link
3875 linkend="external-filter-syntax">syntax</link></literal>
3876 may change in the future.
3883 <term>Example usage:</term>
3885 <screen>+external-filter{fancy-filter}</screen>
3891 <!-- ~~~~~ New section ~~~~~ -->
3892 <sect3 renderas="sect4" id="fast-redirects">
3893 <title>fast-redirects</title>
3897 <term>Typical use:</term>
3899 <para>Fool some click-tracking scripts and speed up indirect links.</para>
3904 <term>Effect:</term>
3907 Detects redirection URLs and redirects the browser without contacting
3908 the redirection server first.
3915 <!-- boolean, parameterized, Multi-value -->
3917 <para>Parameterized.</para>
3922 <term>Parameter:</term>
3927 <quote>simple-check</quote> to just search for the string <quote>http://</quote>
3928 to detect redirection URLs.
3933 <quote>check-decoded-url</quote> to decode URLs (if necessary) before searching
3934 for redirection URLs.
3945 Many sites, like yahoo.com, don't just link to other sites. Instead, they
3946 will link to some script on their own servers, giving the destination as a
3947 parameter, which will then redirect you to the final target. URLs
3948 resulting from this scheme typically look like:
3949 <quote>http://www.example.org/click-tracker.cgi?target=http%3a//www.example.net/</quote>.
3952 Sometimes, there are even multiple consecutive redirects encoded in the
3953 URL. These redirections via scripts make your web browsing more traceable,
3954 since the server from which you follow such a link can see where you go
3955 to. Apart from that, valuable bandwidth and time is wasted, while your
3956 browser asks the server for one redirect after the other. Plus, it feeds
3960 This feature is currently not very smart and is scheduled for improvement.
3961 If it is enabled by default, you will have to create some exceptions to
3962 this action. It can lead to failures in several ways:
3965 Not every URLs with other URLs as parameters is evil.
3966 Some sites offer a real service that requires this information to work.
3967 For example a validation service needs to know, which document to validate.
3968 <literal>fast-redirects</literal> assumes that every URL parameter that
3969 looks like another URL is a redirection target, and will always redirect to
3970 the last one. Most of the time the assumption is correct, but if it isn't,
3971 the user gets redirected anyway.
3974 Another failure occurs if the URL contains other parameters after the URL parameter.
3976 <quote>http://www.example.org/?redirect=http%3a//www.example.net/&foo=bar</quote>.
3977 contains the redirection URL <quote>http://www.example.net/</quote>,
3978 followed by another parameter. <literal>fast-redirects</literal> doesn't know that
3979 and will cause a redirect to <quote>http://www.example.net/&foo=bar</quote>.
3980 Depending on the target server configuration, the parameter will be silently ignored
3981 or lead to a <quote>page not found</quote> error. You can prevent this problem by
3982 first using the <literal><link linkend="redirect">redirect</link></literal> action
3983 to remove the last part of the URL, but it requires a little effort.
3986 To detect a redirection URL, <literal>fast-redirects</literal> only
3987 looks for the string <quote>http://</quote>, either in plain text
3988 (invalid but often used) or encoded as <quote>http%3a//</quote>.
3989 Some sites use their own URL encoding scheme, encrypt the address
3990 of the target server or replace it with a database id. In theses cases
3991 <literal>fast-redirects</literal> is fooled and the request reaches the
3992 redirection server where it probably gets logged.
3998 <term>Example usage:</term>
4001 { +fast-redirects{simple-check} }
4004 { +fast-redirects{check-decoded-url} }
4005 another.example.com/testing</screen>
4013 <!-- ~~~~~ New section ~~~~~ -->
4014 <sect3 renderas="sect4" id="filter">
4015 <title>filter</title>
4019 <term>Typical use:</term>
4021 <para>Get rid of HTML and JavaScript annoyances, banner advertisements (by size),
4022 do fun text replacements, add personalized effects, etc.</para>
4027 <term>Effect:</term>
4030 All instances of text-based type, most notably HTML and JavaScript, to which
4031 this action applies, can be filtered on-the-fly through the specified regular
4032 expression based substitutions. (Note: as of version 3.0.3 plain text documents
4033 are exempted from filtering, because web servers often use the
4034 <literal>text/plain</literal> MIME type for all files whose type they don't know.)
4041 <!-- boolean, parameterized, Multi-value -->
4043 <para>Multi-value.</para>
4048 <term>Parameter:</term>
4051 The name of a content filter, as defined in the <link linkend="filter-file">filter file</link>.
4052 Filters can be defined in one or more files as defined by the
4053 <literal><link linkend="filterfile">filterfile</link></literal>
4054 option in the <link linkend="config">config file</link>.
4055 <filename>default.filter</filename> is the collection of filters
4056 supplied by the developers. Locally defined filters should go
4057 in their own file, such as <filename>user.filter</filename>.
4060 When used in its negative form,
4061 and without parameters, <emphasis>all</emphasis> filtering is completely disabled.
4070 For your convenience, there are a number of pre-defined filters available
4071 in the distribution filter file that you can use. See the examples below for
4075 Filtering requires buffering the page content, which may appear to
4076 slow down page rendering since nothing is displayed until all content has
4077 passed the filters. (The total time until the page is completely rendered
4078 doesn't change much, but it may be perceived as slower since the page is
4079 not incrementally displayed.)
4080 This effect will be more noticeable on slower connections.
4083 <quote>Rolling your own</quote>
4084 filters requires a knowledge of
4085 <ulink url="http://en.wikipedia.org/wiki/Regular_expressions"><quote>Regular
4086 Expressions</quote></ulink> and
4087 <ulink url="http://en.wikipedia.org/wiki/Html"><quote>HTML</quote></ulink>.
4088 This is very powerful feature, and potentially very intrusive.
4089 Filters should be used with caution, and where an equivalent
4090 <quote>action</quote> is not available.
4093 The amount of data that can be filtered is limited to the
4094 <literal><link linkend="buffer-limit">buffer-limit</link></literal>
4095 option in the main <link linkend="config">config file</link>. The
4096 default is 4096 KB (4 Megs). Once this limit is exceeded, the buffered
4097 data, and all pending data, is passed through unfiltered.
4100 Inappropriate MIME types, such as zipped files, are not filtered at all.
4101 (Again, only text-based types except plain text). Encrypted SSL data
4102 (from HTTPS servers) cannot be filtered either, since this would violate
4103 the integrity of the secure transaction. In some situations it might
4104 be necessary to protect certain text, like source code, from filtering
4105 by defining appropriate <literal>-filter</literal> exceptions.
4108 Compressed content can't be filtered either, but if &my-app;
4109 is compiled with zlib support and a supported compression algorithm
4110 is used (gzip or deflate), &my-app; can first decompress the content
4114 If you use a &my-app; version without zlib support, but want filtering to work on
4115 as much documents as possible, even those that would normally be sent compressed,
4116 you must use the <literal><link linkend="prevent-compression">prevent-compression</link></literal>
4117 action in conjunction with <literal>filter</literal>.
4120 Content filtering can achieve some of the same effects as the
4121 <literal><link linkend="block">block</link></literal>
4122 action, i.e. it can be used to block ads and banners. But the mechanism
4123 works quite differently. One effective use, is to block ad banners
4124 based on their size (see below), since many of these seem to be somewhat
4128 <link linkend="contact">Feedback</link> with suggestions for new or
4129 improved filters is particularly welcome!
4132 The below list has only the names and a one-line description of each
4133 predefined filter. There are <link linkend="predefined-filters">more
4134 verbose explanations</link> of what these filters do in the <link
4135 linkend="filter-file">filter file chapter</link>.
4141 <term>Example usage (with filters from the distribution <filename>default.filter</filename> file).
4142 See <link linkend="PREDEFINED-FILTERS">the Predefined Filters section</link> for
4143 more explanation on each:</term>
4146 <anchor id="filter-js-annoyances">
4148 <screen>+filter{js-annoyances} # Get rid of particularly annoying JavaScript abuse.</screen>
4150 <anchor id="filter-js-events">
4152 <screen>+filter{js-events} # Kill JavaScript event bindings and timers (Radically destructive! Only for extra nasty sites).</screen>
4154 <anchor id="filter-html-annoyances">
4156 <screen>+filter{html-annoyances} # Get rid of particularly annoying HTML abuse.</screen>
4158 <anchor id="filter-content-cookies">
4160 <screen>+filter{content-cookies} # Kill cookies that come in the HTML or JS content.</screen>
4162 <anchor id="filter-refresh-tags">
4164 <screen>+filter{refresh-tags} # Kill automatic refresh tags if refresh time is larger than 9 seconds.</screen>
4166 <anchor id="filter-unsolicited-popups">
4168 <screen>+filter{unsolicited-popups} # Disable only unsolicited pop-up windows.</screen>
4170 <anchor id="filter-all-popups">
4172 <screen>+filter{all-popups} # Kill all popups in JavaScript and HTML.</screen>
4174 <anchor id="filter-img-reorder">
4176 <screen>+filter{img-reorder} # Reorder attributes in <img> tags to make the banners-by-* filters more effective.</screen>
4178 <anchor id="filter-banners-by-size">
4180 <screen>+filter{banners-by-size} # Kill banners by size.</screen>
4182 <anchor id="filter-banners-by-link">
4184 <screen>+filter{banners-by-link} # Kill banners by their links to known clicktrackers.</screen>
4186 <anchor id="filter-webbugs">
4188 <screen>+filter{webbugs} # Squish WebBugs (1x1 invisible GIFs used for user tracking).</screen>
4190 <anchor id="filter-tiny-textforms">
4192 <screen>+filter{tiny-textforms} # Extend those tiny textareas up to 40x80 and kill the hard wrap.</screen>
4194 <anchor id="filter-jumping-windows">
4196 <screen>+filter{jumping-windows} # Prevent windows from resizing and moving themselves.</screen>
4198 <anchor id="filter-frameset-borders">
4200 <screen>+filter{frameset-borders} # Give frames a border and make them resizable.</screen>
4202 <anchor id="filter-iframes">
4204 <screen>+filter{iframes} # Removes all detected iframes. Should only be enabled for individual sites.</screen>
4206 <anchor id="filter-demoronizer">
4208 <screen>+filter{demoronizer} # Fix MS's non-standard use of standard charsets.</screen>
4210 <anchor id="filter-shockwave-flash">
4212 <screen>+filter{shockwave-flash} # Kill embedded Shockwave Flash objects.</screen>
4214 <anchor id="filter-quicktime-kioskmode">
4216 <screen>+filter{quicktime-kioskmode} # Make Quicktime movies saveable.</screen>
4218 <anchor id="filter-fun">
4220 <screen>+filter{fun} # Text replacements for subversive browsing fun!</screen>
4222 <anchor id="filter-crude-parental">
4224 <screen>+filter{crude-parental} # Crude parental filtering. Note that this filter doesn't work reliably.</screen>
4226 <anchor id="filter-ie-exploits">
4228 <screen>+filter{ie-exploits} # Disable some known Internet Explorer bug exploits.</screen>
4230 <anchor id="filter-site-specifics">
4232 <screen>+filter{site-specifics} # Cure for site-specific problems. Don't apply generally!</screen>
4234 <anchor id="filter-no-ping">
4236 <screen>+filter{no-ping} # Removes non-standard ping attributes in <a> and <area> tags.</screen>
4238 <anchor id="filter-google">
4240 <screen>+filter{google} # CSS-based block for Google text ads. Also removes a width limitation and the toolbar advertisement.</screen>
4242 <anchor id="filter-yahoo">
4244 <screen>+filter{yahoo} # CSS-based block for Yahoo text ads. Also removes a width limitation.</screen>
4246 <anchor id="filter-msn">
4248 <screen>+filter{msn} # CSS-based block for MSN text ads. Also removes tracking URLs and a width limitation.</screen>
4250 <anchor id="filter-blogspot">
4252 <screen>+filter{blogspot} # Cleans up some Blogspot blogs. Read the fine print before using this.</screen>
4259 <!-- ~~~~~ New section ~~~~~ -->
4260 <sect3 renderas="sect4" id="force-text-mode">
4261 <title>force-text-mode</title>
4267 <term>Typical use:</term>
4269 <para>Force <application>Privoxy</application> to treat a document as if it was in some kind of <emphasis>text</emphasis> format. </para>
4274 <term>Effect:</term>
4277 Declares a document as text, even if the <quote>Content-Type:</quote> isn't detected as such.
4284 <!-- Boolean, Parameterized, Multi-value -->
4286 <para>Boolean.</para>
4291 <term>Parameter:</term>
4303 As explained <literal><link linkend="filter">above</link></literal>,
4304 <application>Privoxy</application> tries to only filter files that are
4305 in some kind of text format. The same restrictions apply to
4306 <literal><link linkend="content-type-overwrite">content-type-overwrite</link></literal>.
4307 <literal>force-text-mode</literal> declares a document as text,
4308 without looking at the <quote>Content-Type:</quote> first.
4312 Think twice before activating this action. Filtering binary data
4313 with regular expressions can cause file damage.
4320 <term>Example usage:</term>
4331 <!-- ~~~~~ New section ~~~~~ -->
4332 <sect3 renderas="sect4" id="forward-override">
4333 <title>forward-override</title>
4339 <term>Typical use:</term>
4341 <para>Change the forwarding settings based on User-Agent or request origin</para>
4346 <term>Effect:</term>
4349 Overrules the forward directives in the configuration file.
4356 <!-- Boolean, Parameterized, Multi-value -->
4358 <para>Parameterized.</para>
4363 <term>Parameter:</term>
4367 <para><quote>forward .</quote> to use a direct connection without any additional proxies.</para>
4371 <quote>forward 127.0.0.1:8123</quote> to use the HTTP proxy listening at 127.0.0.1 port 8123.
4376 <quote>forward-socks4a 127.0.0.1:9050 .</quote> to use the socks4a proxy listening at
4377 127.0.0.1 port 9050. Replace <quote>forward-socks4a</quote> with <quote>forward-socks4</quote>
4378 to use a socks4 connection (with local DNS resolution) instead, use <quote>forward-socks5</quote>
4379 for socks5 connections (with remote DNS resolution).
4384 <quote>forward-socks4a 127.0.0.1:9050 proxy.example.org:8000</quote> to use the socks4a proxy
4385 listening at 127.0.0.1 port 9050 to reach the HTTP proxy listening at proxy.example.org port 8000.
4386 Replace <quote>forward-socks4a</quote> with <quote>forward-socks4</quote> to use a socks4 connection
4387 (with local DNS resolution) instead, use <quote>forward-socks5</quote>
4388 for socks5 connections (with remote DNS resolution).
4393 <quote>forward-webserver 127.0.0.1:80</quote> to use the HTTP
4394 server listening at 127.0.0.1 port 80 without adjusting the
4398 This makes it more convenient to use Privoxy to make
4399 existing websites available as onion services as well.
4402 Many websites serve content with hardcoded URLs and
4403 can't be easily adjusted to change the domain based
4404 on the one used by the client.
4407 Putting Privoxy between Tor and the webserver (or an stunnel
4408 that forwards to the webserver) allows to rewrite headers and
4409 content to make client and server happy at the same time.
4412 Using Privoxy for webservers that are only reachable through
4413 onion addresses and whose location is supposed to be secret
4414 is not recommended and should not be necessary anyway.
4425 This action takes parameters similar to the
4426 <link linkend="forwarding">forward</link> directives in the configuration
4427 file, but without the URL pattern. It can be used as replacement, but normally it's only
4428 used in cases where matching based on the request URL isn't sufficient.
4432 Please read the description for the <link linkend="forwarding">forward</link> directives before
4433 using this action. Forwarding to the wrong people will reduce your privacy and increase the
4434 chances of man-in-the-middle attacks.
4437 If the ports are missing or invalid, default values will be used. This might change
4438 in the future and you shouldn't rely on it. Otherwise incorrect syntax causes Privoxy
4439 to exit. Due to design limitations, invalid parameter syntax isn't detected until the
4440 action is used the first time.
4443 Use the <ulink url="http://config.privoxy.org/show-url-info">show-url-info CGI page</ulink>
4444 to verify that your forward settings do what you thought the do.
4451 <term>Example usage:</term>
4454 # Use an ssh tunnel for requests previously tagged as
4455 # <quote>User-Agent: fetch libfetch/2.0</quote> and make sure
4456 # resuming downloads continues to work.
4458 # This way you can continue to use Tor for your normal browsing,
4459 # without overloading the Tor network with your FreeBSD ports updates
4460 # or downloads of bigger files like ISOs.
4462 # Note that HTTP headers are easy to fake and therefore their
4463 # values are as (un)trustworthy as your clients and users.
4464 {+forward-override{forward-socks5 10.0.0.2:2222 .} \
4465 -hide-if-modified-since \
4466 -overwrite-last-modified \
4468 TAG:^User-Agent: fetch libfetch/2\.0$
4476 <!-- ~~~~~ New section ~~~~~ -->
4477 <sect3 renderas="sect4" id="handle-as-empty-document">
4478 <title>handle-as-empty-document</title>
4484 <term>Typical use:</term>
4486 <para>Mark URLs that should be replaced by empty documents <emphasis>if they get blocked</emphasis></para>
4491 <term>Effect:</term>
4494 This action alone doesn't do anything noticeable. It just marks URLs.
4495 If the <literal><link linkend="block">block</link></literal> action <emphasis>also applies</emphasis>,
4496 the presence or absence of this mark decides whether an HTML <quote>BLOCKED</quote>
4497 page, or an empty document will be sent to the client as a substitute for the blocked content.
4498 The <emphasis>empty</emphasis> document isn't literally empty, but actually contains a single space.
4505 <!-- Boolean, Parameterized, Multi-value -->
4507 <para>Boolean.</para>
4512 <term>Parameter:</term>
4524 Some browsers complain about syntax errors if JavaScript documents
4525 are blocked with <application>Privoxy's</application>
4526 default HTML page; this option can be used to silence them.
4527 And of course this action can also be used to eliminate the &my-app;
4528 BLOCKED message in frames.
4531 The content type for the empty document can be specified with
4532 <literal><link linkend="content-type-overwrite">content-type-overwrite{}</link></literal>,
4533 but usually this isn't necessary.
4539 <term>Example usage:</term>
4541 <screen># Block all documents on example.org that end with ".js",
4542 # but send an empty document instead of the usual HTML message.
4543 {+block{Blocked JavaScript} +handle-as-empty-document}
4552 <!-- ~~~~~ New section ~~~~~ -->
4553 <sect3 renderas="sect4" id="handle-as-image">
4554 <title>handle-as-image</title>
4558 <term>Typical use:</term>
4560 <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>
4565 <term>Effect:</term>
4568 This action alone doesn't do anything noticeable. It just marks URLs as images.
4569 If the <literal><link linkend="block">block</link></literal> action <emphasis>also applies</emphasis>,
4570 the presence or absence of this mark decides whether an HTML <quote>blocked</quote>
4571 page, or a replacement image (as determined by the <literal><link
4572 linkend="set-image-blocker">set-image-blocker</link></literal> action) will be sent to the
4573 client as a substitute for the blocked content.
4580 <!-- Boolean, Parameterized, Multi-value -->
4582 <para>Boolean.</para>
4587 <term>Parameter:</term>
4599 The below generic example section is actually part of <filename>default.action</filename>.
4600 It marks all URLs with well-known image file name extensions as images and should
4604 Users will probably only want to use the handle-as-image action in conjunction with
4605 <literal><link linkend="block">block</link></literal>, to block sources of banners, whose URLs don't
4606 reflect the file type, like in the second example section.
4609 Note that you cannot treat HTML pages as images in most cases. For instance, (in-line) ad
4610 frames require an HTML page to be sent, or they won't display properly.
4611 Forcing <literal>handle-as-image</literal> in this situation will not replace the
4612 ad frame with an image, but lead to error messages.
4618 <term>Example usage (sections):</term>
4620 <screen># Generic image extensions:
4623 /.*\.(gif|jpg|jpeg|png|bmp|ico)$
4625 # These don't look like images, but they're banners and should be
4626 # blocked as images:
4628 {+block{Nasty banners.} +handle-as-image}
4629 nasty-banner-server.example.com/junk.cgi\?output=trash
4637 <!-- ~~~~~ New section ~~~~~ -->
4638 <sect3 renderas="sect4" id="hide-accept-language">
4639 <title>hide-accept-language</title>
4645 <term>Typical use:</term>
4647 <para>Pretend to use different language settings.</para>
4652 <term>Effect:</term>
4655 Deletes or replaces the <quote>Accept-Language:</quote> HTTP header in client requests.
4662 <!-- Boolean, Parameterized, Multi-value -->
4664 <para>Parameterized.</para>
4669 <term>Parameter:</term>
4672 Keyword: <quote>block</quote>, or any user defined value.
4681 Faking the browser's language settings can be useful to make a
4682 foreign User-Agent set with
4683 <literal><link linkend="hide-user-agent">hide-user-agent</link></literal>
4687 However some sites with content in different languages check the
4688 <quote>Accept-Language:</quote> to decide which one to take by default.
4689 Sometimes it isn't possible to later switch to another language without
4690 changing the <quote>Accept-Language:</quote> header first.
4693 Therefore it's a good idea to either only change the
4694 <quote>Accept-Language:</quote> header to languages you understand,
4695 or to languages that aren't wide spread.
4698 Before setting the <quote>Accept-Language:</quote> header
4699 to a rare language, you should consider that it helps to
4700 make your requests unique and thus easier to trace.
4701 If you don't plan to change this header frequently,
4702 you should stick to a common language.
4708 <term>Example usage (section):</term>
4710 <screen># Pretend to use Canadian language settings.
4711 {+hide-accept-language{en-ca} \
4712 +hide-user-agent{Mozilla/5.0 (X11; U; OpenBSD i386; en-CA; rv:1.8.0.4) Gecko/20060628 Firefox/1.5.0.4} \
4722 <!-- ~~~~~ New section ~~~~~ -->
4723 <sect3 renderas="sect4" id="hide-content-disposition">
4724 <title>hide-content-disposition</title>
4730 <term>Typical use:</term>
4732 <para>Prevent download menus for content you prefer to view inside the browser.</para>
4737 <term>Effect:</term>
4740 Deletes or replaces the <quote>Content-Disposition:</quote> HTTP header set by some servers.
4747 <!-- Boolean, Parameterized, Multi-value -->
4749 <para>Parameterized.</para>
4754 <term>Parameter:</term>
4757 Keyword: <quote>block</quote>, or any user defined value.
4766 Some servers set the <quote>Content-Disposition:</quote> HTTP header for
4767 documents they assume you want to save locally before viewing them.
4768 The <quote>Content-Disposition:</quote> header contains the file name
4769 the browser is supposed to use by default.
4772 In most browsers that understand this header, it makes it impossible to
4773 <emphasis>just view</emphasis> the document, without downloading it first,
4774 even if it's just a simple text file or an image.
4777 Removing the <quote>Content-Disposition:</quote> header helps
4778 to prevent this annoyance, but some browsers additionally check the
4779 <quote>Content-Type:</quote> header, before they decide if they can
4780 display a document without saving it first. In these cases, you have
4781 to change this header as well, before the browser stops displaying
4785 It is also possible to change the server's file name suggestion
4786 to another one, but in most cases it isn't worth the time to set
4790 This action will probably be removed in the future,
4791 use server-header filters instead.
4797 <term>Example usage:</term>
4799 <screen># Disarm the download link in Sourceforge's patch tracker
4801 +content-type-overwrite{text/plain}\
4802 +hide-content-disposition{block} }
4803 .sourceforge.net/tracker/download\.php</screen>
4810 <!-- ~~~~~ New section ~~~~~ -->
4811 <sect3 renderas="sect4" id="hide-if-modified-since">
4812 <title>hide-if-modified-since</title>
4818 <term>Typical use:</term>
4820 <para>Prevent yet another way to track the user's steps between sessions.</para>
4825 <term>Effect:</term>
4828 Deletes the <quote>If-Modified-Since:</quote> HTTP client header or modifies its value.
4835 <!-- Boolean, Parameterized, Multi-value -->
4837 <para>Parameterized.</para>
4842 <term>Parameter:</term>
4845 Keyword: <quote>block</quote>, or a user defined value that specifies a range of hours.
4854 Removing this header is useful for filter testing, where you want to force a real
4855 reload instead of getting status code <quote>304</quote>, which would cause the
4856 browser to use a cached copy of the page.
4859 Instead of removing the header, <literal>hide-if-modified-since</literal> can
4860 also add or subtract a random amount of time to/from the header's value.
4861 You specify a range of minutes where the random factor should be chosen from and
4862 <application>Privoxy</application> does the rest. A negative value means
4863 subtracting, a positive value adding.
4866 Randomizing the value of the <quote>If-Modified-Since:</quote> makes
4867 it less likely that the server can use the time as a cookie replacement,
4868 but you will run into caching problems if the random range is too high.
4871 It is a good idea to only use a small negative value and let
4872 <literal><link linkend="overwrite-last-modified">overwrite-last-modified</link></literal>
4873 handle the greater changes.
4876 It is also recommended to use this action together with
4877 <literal><link linkend="crunch-if-none-match">crunch-if-none-match</link></literal>,
4878 otherwise it's more or less pointless.
4884 <term>Example usage (section):</term>
4886 <screen># Let the browser revalidate but make tracking based on the time less likely.
4887 {+hide-if-modified-since{-60} \
4888 +overwrite-last-modified{randomize} \
4889 +crunch-if-none-match}
4897 <!-- ~~~~~ New section ~~~~~ -->
4898 <sect3 renderas="sect4" id="hide-from-header">
4899 <title>hide-from-header</title>
4903 <term>Typical use:</term>
4905 <para>Keep your (old and ill) browser from telling web servers your email address</para>
4910 <term>Effect:</term>
4913 Deletes any existing <quote>From:</quote> HTTP header, or replaces it with the
4921 <!-- Boolean, Parameterized, Multi-value -->
4923 <para>Parameterized.</para>
4928 <term>Parameter:</term>
4931 Keyword: <quote>block</quote>, or any user defined value.
4940 The keyword <quote>block</quote> will completely remove the header
4941 (not to be confused with the <literal><link linkend="block">block</link></literal>
4945 Alternately, you can specify any value you prefer to be sent to the web
4946 server. If you do, it is a matter of fairness not to use any address that
4947 is actually used by a real person.
4950 This action is rarely needed, as modern web browsers don't send
4951 <quote>From:</quote> headers anymore.
4957 <term>Example usage:</term>
4959 <screen>+hide-from-header{block}</screen>
4961 <screen>+hide-from-header{spam-me-senseless@sittingduck.example.com}</screen>
4968 <!-- ~~~~~ New section ~~~~~ -->
4969 <sect3 renderas="sect4" id="hide-referrer">
4970 <title>hide-referrer</title>
4971 <anchor id="hide-referer">
4974 <term>Typical use:</term>
4976 <para>Conceal which link you followed to get to a particular site</para>
4981 <term>Effect:</term>
4984 Deletes the <quote>Referer:</quote> (sic) HTTP header from the client request,
4985 or replaces it with a forged one.
4992 <!-- Boolean, Parameterized, Multi-value -->
4994 <para>Parameterized.</para>
4999 <term>Parameter:</term>
5003 <para><quote>conditional-block</quote> to delete the header completely if the host has changed.</para>
5006 <para><quote>conditional-forge</quote> to forge the header if the host has changed.</para>
5009 <para><quote>block</quote> to delete the header unconditionally.</para>
5012 <para><quote>forge</quote> to pretend to be coming from the homepage of the server we are talking to.</para>
5015 <para>Any other string to set a user defined referrer.</para>
5025 <literal>conditional-block</literal> is the only parameter,
5026 that isn't easily detected in the server's log file. If it blocks the
5027 referrer, the request will look like the visitor used a bookmark or
5028 typed in the address directly.
5031 Leaving the referrer unmodified for requests on the same host
5032 allows the server owner to see the visitor's <quote>click path</quote>,
5033 but in most cases she could also get that information by comparing
5034 other parts of the log file: for example the User-Agent if it isn't
5035 a very common one, or the user's IP address if it doesn't change between
5039 Always blocking the referrer, or using a custom one, can lead to
5040 failures on servers that check the referrer before they answer any
5041 requests, in an attempt to prevent their content from being
5042 embedded or linked to elsewhere.
5045 Both <literal>conditional-block</literal> and <literal>forge</literal>
5046 will work with referrer checks, as long as content and valid referring page
5047 are on the same host. Most of the time that's the case.
5050 <literal>hide-referer</literal> is an alternate spelling of
5051 <literal>hide-referrer</literal> and the two can be can be freely
5052 substituted with each other. (<quote>referrer</quote> is the
5053 correct English spelling, however the HTTP specification has a bug - it
5054 requires it to be spelled as <quote>referer</quote>.)
5060 <term>Example usage:</term>
5062 <screen>+hide-referrer{forge}</screen>
5064 <screen>+hide-referrer{http://www.yahoo.com/}</screen>
5071 <!-- ~~~~~ New section ~~~~~ -->
5072 <sect3 renderas="sect4" id="hide-user-agent">
5073 <title>hide-user-agent</title>
5077 <term>Typical use:</term>
5079 <para>Try to conceal your type of browser and client operating system</para>
5084 <term>Effect:</term>
5087 Replaces the value of the <quote>User-Agent:</quote> HTTP header
5088 in client requests with the specified value.
5095 <!-- Boolean, Parameterized, Multi-value -->
5097 <para>Parameterized.</para>
5102 <term>Parameter:</term>
5105 Any user-defined string.
5115 This can lead to problems on web sites that depend on looking at this header in
5116 order to customize their content for different browsers (which, by the
5117 way, is <emphasis>NOT</emphasis> the right thing to do: good web sites
5118 work browser-independently).
5122 Using this action in multi-user setups or wherever different types of
5123 browsers will access the same <application>Privoxy</application> is
5124 <emphasis>not recommended</emphasis>. In single-user, single-browser
5125 setups, you might use it to delete your OS version information from
5126 the headers, because it is an invitation to exploit known bugs for your
5127 OS. It is also occasionally useful to forge this in order to access
5128 sites that won't let you in otherwise (though there may be a good
5129 reason in some cases).
5132 More information on known user-agent strings can be found at
5133 <ulink url="http://www.user-agents.org/">http://www.user-agents.org/</ulink>
5135 <ulink url="http://en.wikipedia.org/wiki/User_agent">http://en.wikipedia.org/wiki/User_agent</ulink>.
5141 <term>Example usage:</term>
5143 <screen>+hide-user-agent{Netscape 6.1 (X11; I; Linux 2.4.18 i686)}</screen>
5150 <!-- ~~~~~ New section ~~~~~ -->
5151 <sect3 renderas="sect4" id="https-inspection">
5152 <title>https-inspection</title>
5156 <term>Typical use:</term>
5158 <para>Filter encrypted requests and responses</para>
5163 <term>Effect:</term>
5166 Encrypted requests are decrypted, filtered and forwarded encrypted.
5173 <!-- boolean, parameterized, Multi-value -->
5175 <para>Boolean.</para>
5180 <term>Parameter:</term>
5192 This action allows &my-app; to filter encrypted requests and responses.
5193 For this to work &my-app; has to generate a certificate and send it
5194 to the client which has to accept it.
5197 Before this works the directives in the
5198 <literal><ulink url="config.html#TLS">TLS section</ulink></literal>
5199 of the config file have to be configured.
5202 Note that the action has to be enabled based on the CONNECT
5203 request which doesn't contain a path. Enabling it based on
5204 a pattern with path doesn't work as the path is only seen
5205 by &my-app; if the action is already enabled.
5211 <term>Example usage (section):</term>
5213 <screen>{+https-inspection}
5214 www.example.com</screen>
5222 <!-- ~~~~~ New section ~~~~~ -->
5223 <sect3 renderas="sect4" id="ignore-certificate-errors">
5224 <title>ignore-certificate-errors</title>
5228 <term>Typical use:</term>
5230 <para>Filter encrypted requests and responses without verifying the certificate</para>
5235 <term>Effect:</term>
5238 Encrypted requests are forwarded to sites without verifying the certificate.
5245 <!-- Boolean, Parameterized, Multi-value -->
5247 <para>Boolean.</para>
5252 <term>Parameter:</term>
5265 <link linkend="HTTPS-INSPECTION"><quote>+https-inspection</quote></link>
5266 action is used &my-app; by default verifies that the remote site uses a valid
5270 If the certificate is invalid the connection is aborted.
5273 This action disabled the certificate check allowing requests to sites
5274 with invalid certificates.
5280 <term>Example usage:</term>
5283 {+ignore-certificate-errors}
5292 <!-- ~~~~~ New section ~~~~~ -->
5293 <sect3 renderas="sect4" id="limit-connect">
5294 <title>limit-connect</title>
5298 <term>Typical use:</term>
5300 <para>Prevent abuse of <application>Privoxy</application> as a TCP proxy relay or disable SSL for untrusted sites</para>
5305 <term>Effect:</term>
5308 Specifies to which ports HTTP CONNECT requests are allowable.
5315 <!-- Boolean, Parameterized, Multi-value -->
5317 <para>Parameterized.</para>
5322 <term>Parameter:</term>
5325 A comma-separated list of ports or port ranges (the latter using dashes, with the minimum
5326 defaulting to 0 and the maximum to 65K).
5335 By default, i.e. if no <literal>limit-connect</literal> action applies,
5336 <application>Privoxy</application> allows HTTP CONNECT requests to all
5337 ports. Use <literal>limit-connect</literal> if fine-grained control
5338 is desired for some or all destinations.
5341 The CONNECT methods exists in HTTP to allow access to secure websites
5342 (<quote>https://</quote> URLs) through proxies. It works very simply:
5343 the proxy connects to the server on the specified port, and then
5344 short-circuits its connections to the client and to the remote server.
5345 This means CONNECT-enabled proxies can be used as TCP relays very easily.
5348 <application>Privoxy</application> relays HTTPS traffic without seeing
5349 the decoded content. Websites can leverage this limitation to circumvent &my-app;'s
5350 filters. By specifying an invalid port range you can disable HTTPS entirely.
5356 <term>Example usages:</term>
5358 <!-- I had trouble getting the spacing to look right in my browser -->
5359 <!-- I probably have the wrong font setup, bollocks. -->
5360 <!-- Apparently the emphasis tag uses a proportional font no matter what -->
5361 <screen>+limit-connect{443} # Port 443 is OK.
5362 +limit-connect{80,443} # Ports 80 and 443 are OK.
5363 +limit-connect{-3, 7, 20-100, 500-} # Ports less than 3, 7, 20 to 100 and above 500 are OK.
5364 +limit-connect{-} # All ports are OK
5365 +limit-connect{,} # No HTTPS/SSL traffic is allowed</screen>
5372 <!-- ~~~~~ New section ~~~~~ -->
5373 <sect3 renderas="sect4" id="limit-cookie-lifetime">
5374 <title>limit-cookie-lifetime</title>
5378 <term>Typical use:</term>
5380 <para>Limit the lifetime of HTTP cookies to a couple of minutes or hours.</para>
5385 <term>Effect:</term>
5388 Overwrites the expires field in Set-Cookie server headers if it's above the specified limit.
5395 <!-- Boolean, Parameterized, Multi-value -->
5397 <para>Parameterized.</para>
5402 <term>Parameter:</term>
5405 The lifetime limit in minutes, or 0.
5414 This action reduces the lifetime of HTTP cookies coming from the
5415 server to the specified number of minutes, starting from the time
5416 the cookie passes Privoxy.
5419 Cookies with a lifetime below the limit are not modified.
5420 The lifetime of session cookies is set to the specified limit.
5423 The effect of this action depends on the server.
5426 In case of servers which refresh their cookies with each response
5427 (or at least frequently), the lifetime limit set by this action
5429 Thus, a session associated with the cookie continues to work with
5430 this action enabled, as long as a new request is made before the
5431 last limit set is reached.
5434 However, some servers send their cookies once, with a lifetime of several
5435 years (the year 2037 is a popular choice), and do not refresh them
5436 until a certain event in the future, for example the user logging out.
5437 In this case this action may limit the absolute lifetime of the session,
5438 even if requests are made frequently.
5441 If the parameter is <quote>0</quote>, this action behaves like
5442 <literal><link linkend="session-cookies-only">session-cookies-only</link></literal>.
5448 <term>Example usages:</term>
5450 <screen>+limit-cookie-lifetime{60}</screen>
5456 <!-- ~~~~~ New section ~~~~~ -->
5457 <sect3 renderas="sect4" id="prevent-compression">
5458 <title>prevent-compression</title>
5462 <term>Typical use:</term>
5465 Ensure that servers send the content uncompressed, so it can be
5466 passed through <literal><link linkend="filter">filter</link></literal>s.
5472 <term>Effect:</term>
5475 Removes the Accept-Encoding header which can be used to ask for compressed transfer.
5482 <!-- Boolean, Parameterized, Multi-value -->
5484 <para>Boolean.</para>
5489 <term>Parameter:</term>
5501 More and more websites send their content compressed by default, which
5502 is generally a good idea and saves bandwidth. But the <literal><link
5503 linkend="filter">filter</link></literal> and
5504 <literal><link linkend="deanimate-gifs">deanimate-gifs</link></literal>
5505 actions need access to the uncompressed data.
5508 When compiled with zlib support (available since &my-app; 3.0.7), content that should be
5509 filtered is decompressed on-the-fly and you don't have to worry about this action.
5510 If you are using an older &my-app; version, or one that hasn't been compiled with zlib
5511 support, this action can be used to convince the server to send the content uncompressed.
5514 Most text-based instances compress very well, the size is seldom decreased by less than 50%,
5515 for markup-heavy instances like news feeds saving more than 90% of the original size isn't
5519 Not using compression will therefore slow down the transfer, and you should only
5520 enable this action if you really need it. As of &my-app; 3.0.7 it's disabled in all
5521 predefined action settings.
5524 Note that some (rare) ill-configured sites don't handle requests for uncompressed
5525 documents correctly. Broken PHP applications tend to send an empty document body,
5526 some IIS versions only send the beginning of the content. If you enable
5527 <literal>prevent-compression</literal> per default, you might want to add
5528 exceptions for those sites. See the example for how to do that.
5534 <term>Example usage (sections):</term>
5537 # Selectively turn off compression, and enable a filter
5539 { +filter{tiny-textforms} +prevent-compression }
5540 # Match only these sites
5545 # Or instead, we could set a universal default:
5547 { +prevent-compression }
5550 # Then maybe make exceptions for broken sites:
5552 { -prevent-compression }
5553 .compusa.com/</screen>
5561 <!-- ~~~~~ New section ~~~~~ -->
5562 <sect3 renderas="sect4" id="overwrite-last-modified">
5563 <title>overwrite-last-modified</title>
5569 <term>Typical use:</term>
5571 <para>Prevent yet another way to track the user's steps between sessions.</para>
5576 <term>Effect:</term>
5579 Deletes the <quote>Last-Modified:</quote> HTTP server header or modifies its value.
5586 <!-- Boolean, Parameterized, Multi-value -->
5588 <para>Parameterized.</para>
5593 <term>Parameter:</term>
5596 One of the keywords: <quote>block</quote>, <quote>reset-to-request-time</quote>
5597 and <quote>randomize</quote>
5606 Removing the <quote>Last-Modified:</quote> header is useful for filter
5607 testing, where you want to force a real reload instead of getting status
5608 code <quote>304</quote>, which would cause the browser to reuse the old
5609 version of the page.
5612 The <quote>randomize</quote> option overwrites the value of the
5613 <quote>Last-Modified:</quote> header with a randomly chosen time
5614 between the original value and the current time. In theory the server
5615 could send each document with a different <quote>Last-Modified:</quote>
5616 header to track visits without using cookies. <quote>Randomize</quote>
5617 makes it impossible and the browser can still revalidate cached documents.
5620 <quote>reset-to-request-time</quote> overwrites the value of the
5621 <quote>Last-Modified:</quote> header with the current time. You could use
5622 this option together with
5623 <literal><link linkend="hide-if-modified-since">hide-if-modified-since</link></literal>
5624 to further customize your random range.
5627 The preferred parameter here is <quote>randomize</quote>. It is safe
5628 to use, as long as the time settings are more or less correct.
5629 If the server sets the <quote>Last-Modified:</quote> header to the time
5630 of the request, the random range becomes zero and the value stays the same.
5631 Therefore you should later randomize it a second time with
5632 <literal><link linkend="hide-if-modified-since">hided-if-modified-since</link></literal>,
5636 It is also recommended to use this action together with
5637 <literal><link linkend="crunch-if-none-match">crunch-if-none-match</link></literal>.
5643 <term>Example usage:</term>
5645 <screen># Let the browser revalidate without being tracked across sessions
5646 { +hide-if-modified-since{-60} \
5647 +overwrite-last-modified{randomize} \
5648 +crunch-if-none-match}
5656 <!-- ~~~~~ New section ~~~~~ -->
5657 <sect3 renderas="sect4" id="redirect">
5658 <title>redirect</title>
5664 <term>Typical use:</term>
5667 Redirect requests to other sites.
5673 <term>Effect:</term>
5676 Convinces the browser that the requested document has been moved
5677 to another location and the browser should get it from there.
5684 <!-- Boolean, Parameterized, Multi-value -->
5686 <para>Parameterized</para>
5691 <term>Parameter:</term>
5694 An absolute URL or a single pcrs command.
5703 Requests to which this action applies are answered with a
5704 HTTP redirect to URLs of your choosing. The new URL is
5705 either provided as parameter, or derived by applying a
5706 single pcrs command to the original URL.
5709 The syntax for pcrs commands is documented in the
5710 <link linkend="filter-file">filter file</link> section.
5713 Requests can't be blocked and redirected at the same time,
5714 applying this action together with
5715 <literal><link linkend="block">block</link></literal>
5716 is a configuration error. Currently the request is blocked
5717 and an error message logged, the behavior may change in the
5718 future and result in Privoxy rejecting the action file.
5721 This action can be combined with
5722 <literal><link linkend="fast-redirects">fast-redirects{check-decoded-url}</link></literal>
5723 to redirect to a decoded version of a rewritten URL.
5726 Use this action carefully, make sure not to create redirection loops
5727 and be aware that using your own redirects might make it
5728 possible to fingerprint your requests.
5731 In case of problems with your redirects, or simply to watch
5732 them working, enable <link linkend="DEBUG">debug 128</link>.
5738 <term>Example usages:</term>
5740 <screen># Replace example.com's style sheet with another one
5741 { +redirect{http://localhost/css-replacements/example.com.css} }
5742 example.com/stylesheet\.css
5744 # Create a short, easy to remember nickname for a favorite site
5745 # (relies on the browser to accept and forward invalid URLs to &my-app;)
5746 { +redirect{https://www.privoxy.org/user-manual/actions-file.html} }
5749 # Always use the expanded view for Undeadly.org articles
5750 # (Note the $ at the end of the URL pattern to make sure
5751 # the request for the rewritten URL isn't redirected as well)
5752 {+redirect{s@$@&mode=expanded@}}
5753 undeadly.org/cgi\?action=article&sid=\d*$
5755 # Redirect Google search requests to MSN
5756 {+redirect{s@^http://[^/]*/search\?q=([^&]*).*@http://search.msn.com/results.aspx?q=$1@}}
5759 # Redirect MSN search requests to Yahoo
5760 {+redirect{s@^http://[^/]*/results\.aspx\?q=([^&]*).*@http://search.yahoo.com/search?p=$1@}}
5761 search.msn.com//results\.aspx\?q=
5763 # Redirect http://example.com/&bla=fasel&toChange=foo (and any other value but "bar")
5764 # to http://example.com/&bla=fasel&toChange=bar
5766 # The URL pattern makes sure that the following request isn't redirected again.
5767 {+redirect{s@toChange=[^&]+@toChange=bar@}}
5768 example.com/.*toChange=(?!bar)
5770 # Add a shortcut to look up illumos bugs
5771 {+redirect{s@^http://i([0-9]+)/.*@https://www.illumos.org/issues/$1@}}
5772 # Redirected URL = http://i4974/
5773 # Redirect Destination = https://www.illumos.org/issues/4974
5774 i[0-9][0-9][0-9][0-9]*/
5776 # Redirect remote requests for this manual
5777 # to the local version delivered by Privoxy
5778 {+redirect{s@^http://www@http://config@}}
5779 www.privoxy.org/user-manual/</screen>
5787 <!-- ~~~~~ New section ~~~~~ -->
5788 <sect3 renderas="sect4" id="server-header-filter">
5789 <title>server-header-filter</title>
5793 <term>Typical use:</term>
5796 Rewrite or remove single server headers.
5802 <term>Effect:</term>
5805 All server headers to which this action applies are filtered on-the-fly
5806 through the specified regular expression based substitutions.
5813 <!-- boolean, parameterized, Multi-value -->
5815 <para>Multi-value.</para>
5820 <term>Parameter:</term>
5823 The name of a server-header filter, as defined in one of the
5824 <link linkend="filter-file">filter files</link>.
5833 Server-header filters are applied to each header on its own, not to
5834 all at once. This makes it easier to diagnose problems, but on the downside
5835 you can't write filters that only change header x if header y's value is z.
5836 You can do that by using tags though.
5839 Server-header filters are executed after the other header actions have finished
5840 and use their output as input.
5843 Please refer to the <link linkend="filter-file">filter file chapter</link>
5844 to learn which server-header filters are available by default, and how to
5851 <term>Example usage (section):</term>
5854 {+server-header-filter{html-to-xml}}
5855 example.org/xml-instance-that-is-delivered-as-html
5857 {+server-header-filter{xml-to-html}}
5858 example.org/instance-that-is-delivered-as-xml-but-is-not
5867 <!-- ~~~~~ New section ~~~~~ -->
5868 <sect3 renderas="sect4" id="server-header-tagger">
5869 <title>server-header-tagger</title>
5873 <term>Typical use:</term>
5876 Enable or disable filters based on the Content-Type header.
5882 <term>Effect:</term>
5885 Server headers to which this action applies are filtered on-the-fly through
5886 the specified regular expression based substitutions, the result is used as
5894 <!-- boolean, parameterized, Multi-value -->
5896 <para>Multi-value.</para>
5901 <term>Parameter:</term>
5904 The name of a server-header tagger, as defined in one of the
5905 <link linkend="filter-file">filter files</link>.
5914 Server-header taggers are applied to each header on its own,
5915 and as the header isn't modified, each tagger <quote>sees</quote>
5919 Server-header taggers are executed before all other header actions
5920 that modify server headers. Their tags can be used to control
5921 all of the other server-header actions, the content filters
5922 and the crunch actions (<link linkend="redirect">redirect</link>
5923 and <link linkend="block">block</link>).
5926 Obviously crunching based on tags created by server-header taggers
5927 doesn't prevent the request from showing up in the server's log file.
5934 <term>Example usage (section):</term>
5937 # Tag every request with the content type declared by the server
5938 {+server-header-tagger{content-type}}
5941 # If the response has a tag starting with 'image/' enable an external
5942 # filter that only applies to images.
5944 # Note that the filter is not available by default, it's just a
5945 # <literal><link linkend="external-filter-syntax">silly example</link></literal>.
5946 {+external-filter{rotate-image} +force-text-mode}
5956 <!-- ~~~~~ New section ~~~~~ -->
5957 <sect3 renderas="sect4" id="session-cookies-only">
5958 <title>session-cookies-only</title>
5962 <term>Typical use:</term>
5965 Allow only temporary <quote>session</quote> cookies (for the current
5966 browser session <emphasis>only</emphasis>).
5972 <term>Effect:</term>
5975 Deletes the <quote>expires</quote> field from <quote>Set-Cookie:</quote>
5976 server headers. Most browsers will not store such cookies permanently and
5977 forget them in between sessions.
5984 <!-- Boolean, Parameterized, Multi-value -->
5986 <para>Boolean.</para>
5991 <term>Parameter:</term>
6003 This is less strict than <literal><link linkend="crunch-incoming-cookies">crunch-incoming-cookies</link></literal> /
6004 <literal><link linkend="crunch-outgoing-cookies">crunch-outgoing-cookies</link></literal> and allows you to browse
6005 websites that insist or rely on setting cookies, without compromising your privacy too badly.
6008 Most browsers will not permanently store cookies that have been processed by
6009 <literal>session-cookies-only</literal> and will forget about them between sessions.
6010 This makes profiling cookies useless, but won't break sites which require cookies so
6011 that you can log in for transactions. This is generally turned on for all
6012 sites, and is the recommended setting.
6015 It makes <emphasis>no sense at all</emphasis> to use <literal>session-cookies-only</literal>
6016 together with <literal><link linkend="crunch-incoming-cookies">crunch-incoming-cookies</link></literal> or
6017 <literal><link linkend="crunch-outgoing-cookies">crunch-outgoing-cookies</link></literal>. If you do, cookies
6018 will be plainly killed.
6021 Note that it is up to the browser how it handles such cookies without an <quote>expires</quote>
6022 field. If you use an exotic browser, you might want to try it out to be sure.
6025 This setting also has no effect on cookies that may have been stored
6026 previously by the browser before starting <application>Privoxy</application>.
6027 These would have to be removed manually.
6030 <application>Privoxy</application> also uses
6031 the <link linkend="filter-content-cookies">content-cookies filter</link>
6032 to block some types of cookies. Content cookies are not effected by
6033 <literal>session-cookies-only</literal>.
6039 <term>Example usage:</term>
6041 <screen>+session-cookies-only</screen>
6048 <!-- ~~~~~ New section ~~~~~ -->
6049 <sect3 renderas="sect4" id="set-image-blocker">
6050 <title>set-image-blocker</title>
6054 <term>Typical use:</term>
6056 <para>Choose the replacement for blocked images</para>
6061 <term>Effect:</term>
6064 This action alone doesn't do anything noticeable. If <emphasis>both</emphasis>
6065 <literal><link linkend="block">block</link></literal> <emphasis>and</emphasis> <literal><link
6066 linkend="handle-as-image">handle-as-image</link></literal> <emphasis>also</emphasis>
6067 apply, i.e. if the request is to be blocked as an image,
6068 <emphasis>then</emphasis> the parameter of this action decides what will be
6069 sent as a replacement.
6076 <!-- Boolean, Parameterized, Multi-value -->
6078 <para>Parameterized.</para>
6083 <term>Parameter:</term>
6088 <quote>pattern</quote> to send a built-in checkerboard pattern image. The image is visually
6089 decent, scales very well, and makes it obvious where banners were busted.
6094 <quote>blank</quote> to send a built-in transparent image. This makes banners disappear
6095 completely, but makes it hard to detect where <application>Privoxy</application> has blocked
6096 images on a given page and complicates troubleshooting if <application>Privoxy</application>
6097 has blocked innocent images, like navigation icons.
6102 <quote><replaceable class="parameter">target-url</replaceable></quote> to
6103 send a redirect to <replaceable class="parameter">target-url</replaceable>. You can redirect
6104 to any image anywhere, even in your local filesystem via <quote>file:///</quote> URL.
6105 (But note that not all browsers support redirecting to a local file system).
6108 A good application of redirects is to use special <application>Privoxy</application>-built-in
6109 URLs, which send the built-in images, as <replaceable class="parameter">target-url</replaceable>.
6110 This has the same visual effect as specifying <quote>blank</quote> or <quote>pattern</quote> in
6111 the first place, but enables your browser to cache the replacement image, instead of requesting
6112 it over and over again.
6123 The URLs for the built-in images are <quote>http://config.privoxy.org/send-banner?type=<replaceable
6124 class="parameter">type</replaceable></quote>, where <replaceable class="parameter">type</replaceable> is
6125 either <quote>blank</quote> or <quote>pattern</quote>.
6128 There is a third (advanced) type, called <quote>auto</quote>. It is <emphasis>NOT</emphasis> to be
6129 used in <literal>set-image-blocker</literal>, but meant for use from <link linkend="filter-file">filters</link>.
6130 Auto will select the type of image that would have applied to the referring page, had it been an image.
6136 <term>Example usage:</term>
6141 <screen>+set-image-blocker{pattern}</screen>
6143 Redirect to the BSD daemon:
6145 <screen>+set-image-blocker{http://www.freebsd.org/gifs/dae_up3.gif}</screen>
6147 Redirect to the built-in pattern for better caching:
6149 <screen>+set-image-blocker{http://config.privoxy.org/send-banner?type=pattern}</screen>
6156 <!-- ~~~~~ New section ~~~~~ -->
6157 <sect3 id="summary">
6158 <title>Summary</title>
6160 Note that many of these actions have the potential to cause a page to
6161 misbehave, possibly even not to display at all. There are many ways
6162 a site designer may choose to design his site, and what HTTP header
6163 content, and other criteria, he may depend on. There is no way to have hard
6164 and fast rules for all sites. See the <link
6165 linkend="ACTIONSANAT">Appendix</link> for a brief example on troubleshooting
6171 <!-- ~~~~~ New section ~~~~~ -->
6172 <sect2 id="aliases">
6173 <title>Aliases</title>
6175 Custom <quote>actions</quote>, known to <application>Privoxy</application>
6176 as <quote>aliases</quote>, can be defined by combining other actions.
6177 These can in turn be invoked just like the built-in actions.
6178 Currently, an alias name can contain any character except space, tab,
6180 <quote>{</quote> and <quote>}</quote>, but we <emphasis>strongly
6181 recommend</emphasis> that you only use <quote>a</quote> to <quote>z</quote>,
6182 <quote>0</quote> to <quote>9</quote>, <quote>+</quote>, and <quote>-</quote>.
6183 Alias names are not case sensitive, and are not required to start with a
6184 <quote>+</quote> or <quote>-</quote> sign, since they are merely textually
6188 Aliases can be used throughout the actions file, but they <emphasis>must be
6189 defined in a special section at the top of the file!</emphasis>
6190 And there can only be one such section per actions file. Each actions file may
6191 have its own alias section, and the aliases defined in it are only visible
6195 There are two main reasons to use aliases: One is to save typing for frequently
6196 used combinations of actions, the other one is a gain in flexibility: If you
6197 decide once how you want to handle shops by defining an alias called
6198 <quote>shop</quote>, you can later change your policy on shops in
6199 <emphasis>one</emphasis> place, and your changes will take effect everywhere
6200 in the actions file where the <quote>shop</quote> alias is used. Calling aliases
6201 by their purpose also makes your actions files more readable.
6204 Currently, there is one big drawback to using aliases, though:
6205 <application>Privoxy</application>'s built-in web-based action file
6206 editor honors aliases when reading the actions files, but it expands
6207 them before writing. So the effects of your aliases are of course preserved,
6208 but the aliases themselves are lost when you edit sections that use aliases
6213 Now let's define some aliases...
6217 # Useful custom aliases we can use later.
6219 # Note the (required!) section header line and that this section
6220 # must be at the top of the actions file!
6224 # These aliases just save typing later:
6225 # (Note that some already use other aliases!)
6227 +crunch-all-cookies = +<link linkend="CRUNCH-INCOMING-COOKIES">crunch-incoming-cookies</link> +<link linkend="CRUNCH-OUTGOING-COOKIES">crunch-outgoing-cookies</link>
6228 -crunch-all-cookies = -<link linkend="CRUNCH-INCOMING-COOKIES">crunch-incoming-cookies</link> -<link linkend="CRUNCH-OUTGOING-COOKIES">crunch-outgoing-cookies</link>
6229 +block-as-image = +block{Blocked image.} +handle-as-image
6230 allow-all-cookies = -crunch-all-cookies -<link linkend="SESSION-COOKIES-ONLY">session-cookies-only</link> -<link linkend="FILTER-CONTENT-COOKIES">filter{content-cookies}</link>
6232 # These aliases define combinations of actions
6233 # that are useful for certain types of sites:
6235 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>
6237 shop = -crunch-all-cookies -<link linkend="FILTER-ALL-POPUPS">filter{all-popups}</link>
6239 # Short names for other aliases, for really lazy people ;-)
6241 c0 = +crunch-all-cookies
6242 c1 = -crunch-all-cookies</screen>
6245 ...and put them to use. These sections would appear in the lower part of an
6246 actions file and define exceptions to the default actions (as specified further
6247 up for the <quote>/</quote> pattern):
6251 # These sites are either very complex or very keen on
6252 # user data and require minimal interference to work:
6255 .office.microsoft.com
6256 .windowsupdate.microsoft.com
6257 # Gmail is really mail.google.com, not gmail.com
6261 # Allow cookies (for setting and retrieving your customer data)
6265 .worldpay.com # for quietpc.com
6268 # These shops require pop-ups:
6270 {-filter{all-popups} -filter{unsolicited-popups}}
6272 .overclockers.co.uk</screen>
6275 Aliases like <quote>shop</quote> and <quote>fragile</quote> are typically used for
6276 <quote>problem</quote> sites that require more than one action to be disabled
6277 in order to function properly.
6283 <!-- ~~~~~ New section ~~~~~ -->
6284 <sect2 id="act-examples">
6285 <title>Actions Files Tutorial</title>
6287 The above chapters have shown <link linkend="actions-file">which actions files
6288 there are and how they are organized</link>, how actions are <link
6289 linkend="actions">specified</link> and <link linkend="actions-apply">applied
6290 to URLs</link>, how <link linkend="af-patterns">patterns</link> work, and how to
6291 define and use <link linkend="aliases">aliases</link>. Now, let's look at an
6292 example <filename>match-all.action</filename>, <filename>default.action</filename>
6293 and <filename>user.action</filename> file and see how all these pieces come together:
6296 <sect3 id="match-all">
6297 <title>match-all.action</title>
6299 Remember <emphasis>all actions are disabled when matching starts</emphasis>,
6300 so we have to explicitly enable the ones we want.
6304 While the <filename>match-all.action</filename> file only contains a
6305 single section, it is probably the most important one. It has only one
6306 pattern, <quote><literal>/</literal></quote>, but this pattern
6307 <link linkend="af-patterns">matches all URLs</link>. Therefore, the set of
6308 actions used in this <quote>default</quote> section <emphasis>will
6309 be applied to all requests as a start</emphasis>. It can be partly or
6310 wholly overridden by other actions files like <filename>default.action</filename>
6311 and <filename>user.action</filename>, but it will still be largely responsible
6312 for your overall browsing experience.
6316 Again, at the start of matching, all actions are disabled, so there is
6317 no need to disable any actions here. (Remember: a <quote>+</quote>
6318 preceding the action name enables the action, a <quote>-</quote> disables!).
6319 Also note how this long line has been made more readable by splitting it into
6320 multiple lines with line continuation.
6325 +<link linkend="CHANGE-X-FORWARDED-FOR">change-x-forwarded-for{block}</link> \
6326 +<link linkend="HIDE-FROM-HEADER">hide-from-header{block}</link> \
6327 +<link linkend="SET-IMAGE-BLOCKER">set-image-blocker{pattern}</link> \
6333 The default behavior is now set.
6337 <sect3 id="default-action">
6338 <title>default.action</title>
6341 If you aren't a developer, there's no need for you to edit the
6342 <filename>default.action</filename> file. It is maintained by
6343 the &my-app; developers and if you disagree with some of the
6344 sections, you should overrule them in your <filename>user.action</filename>.
6348 Understanding the <filename>default.action</filename> file can
6349 help you with your <filename>user.action</filename>, though.
6353 The first section in this file is a special section for internal use
6354 that prevents older &my-app; versions from reading the file:
6358 ##########################################################################
6359 # Settings -- Don't change! For internal Privoxy use ONLY.
6360 ##########################################################################
6362 for-privoxy-version=3.0.11</screen>
6365 After that comes the (optional) alias section. We'll use the example
6366 section from the above <link linkend="aliases">chapter on aliases</link>,
6367 that also explains why and how aliases are used:
6371 ##########################################################################
6373 ##########################################################################
6376 # These aliases just save typing later:
6377 # (Note that some already use other aliases!)
6379 +crunch-all-cookies = +<link linkend="CRUNCH-INCOMING-COOKIES">crunch-incoming-cookies</link> +<link linkend="CRUNCH-OUTGOING-COOKIES">crunch-outgoing-cookies</link>
6380 -crunch-all-cookies = -<link linkend="CRUNCH-INCOMING-COOKIES">crunch-incoming-cookies</link> -<link linkend="CRUNCH-OUTGOING-COOKIES">crunch-outgoing-cookies</link>
6381 +block-as-image = +block{Blocked image.} +handle-as-image
6382 mercy-for-cookies = -crunch-all-cookies -<link linkend="SESSION-COOKIES-ONLY">session-cookies-only</link> -<link linkend="FILTER-CONTENT-COOKIES">filter{content-cookies}</link>
6384 # These aliases define combinations of actions
6385 # that are useful for certain types of sites:
6387 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>
6388 shop = -crunch-all-cookies -<link linkend="FILTER-ALL-POPUPS">filter{all-popups}</link></screen>
6391 The first of our specialized sections is concerned with <quote>fragile</quote>
6392 sites, i.e. sites that require minimum interference, because they are either
6393 very complex or very keen on tracking you (and have mechanisms in place that
6394 make them unusable for people who avoid being tracked). We will use
6395 our pre-defined <literal>fragile</literal> alias instead of stating the list
6396 of actions explicitly:
6400 ##########################################################################
6401 # Exceptions for sites that'll break under the default action set:
6402 ##########################################################################
6404 # "Fragile" Use a minimum set of actions for these sites (see alias above):
6407 .office.microsoft.com # surprise, surprise!
6408 .windowsupdate.microsoft.com
6409 mail.google.com</screen>
6412 Shopping sites are not as fragile, but they typically
6413 require cookies to log in, and pop-up windows for shopping
6414 carts or item details. Again, we'll use a pre-defined alias:
6422 .worldpay.com # for quietpc.com
6424 .scan.co.uk</screen>
6427 The <literal><link linkend="FAST-REDIRECTS">fast-redirects</link></literal>
6428 action, which may have been enabled in <filename>match-all.action</filename>,
6429 breaks some sites. So disable it for popular sites where we know it misbehaves:
6433 { -<link linkend="FAST-REDIRECTS">fast-redirects</link> }
6437 .altavista.com/.*(like|url|link):http
6438 .altavista.com/trans.*urltext=http
6439 .nytimes.com</screen>
6442 It is important that <application>Privoxy</application> knows which
6443 URLs belong to images, so that <emphasis>if</emphasis> they are to
6444 be blocked, a substitute image can be sent, rather than an HTML page.
6445 Contacting the remote site to find out is not an option, since it
6446 would destroy the loading time advantage of banner blocking, and it
6447 would feed the advertisers information about you. We can mark any
6448 URL as an image with the <literal><link
6449 linkend="handle-as-image">handle-as-image</link></literal> action,
6450 and marking all URLs that end in a known image file extension is a
6455 ##########################################################################
6457 ##########################################################################
6459 # Define which file types will be treated as images, in case they get
6460 # blocked further down this file:
6462 { +<link linkend="HANDLE-AS-IMAGE">handle-as-image</link> }
6463 /.*\.(gif|jpe?g|png|bmp|ico)$</screen>
6466 And then there are known banner sources. They often use scripts to
6467 generate the banners, so it won't be visible from the URL that the
6468 request is for an image. Hence we block them <emphasis>and</emphasis>
6469 mark them as images in one go, with the help of our
6470 <literal>+block-as-image</literal> alias defined above. (We could of
6471 course just as well use <literal>+<link linkend="block">block</link>
6472 +<link linkend="handle-as-image">handle-as-image</link></literal> here.)
6473 Remember that the type of the replacement image is chosen by the
6474 <literal><link linkend="set-image-blocker">set-image-blocker</link></literal>
6475 action. Since all URLs have matched the default section with its
6476 <literal>+<link linkend="set-image-blocker">set-image-blocker</link>{pattern}</literal>
6477 action before, it still applies and needn't be repeated:
6481 # Known ad generators:
6486 .ad.*.doubleclick.net
6487 .a.yimg.com/(?:(?!/i/).)*$
6488 .a[0-9].yimg.com/(?:(?!/i/).)*$
6493 One of the most important jobs of <application>Privoxy</application>
6494 is to block banners. Many of these can be <quote>blocked</quote>
6495 by the <literal><link linkend="filter">filter</link>{banners-by-size}</literal>
6496 action, which we enabled above, and which deletes the references to banner
6497 images from the pages while they are loaded, so the browser doesn't request
6498 them anymore, and hence they don't need to be blocked here. But this naturally
6499 doesn't catch all banners, and some people choose not to use filters, so we
6500 need a comprehensive list of patterns for banner URLs here, and apply the
6501 <literal><link linkend="block">block</link></literal> action to them.
6504 First comes many generic patterns, which do most of the work, by
6505 matching typical domain and path name components of banners. Then comes
6506 a list of individual patterns for specific sites, which is omitted here
6507 to keep the example short:
6511 ##########################################################################
6512 # Block these fine banners:
6513 ##########################################################################
6514 { <link linkend="BLOCK">+block{Banner ads.}</link> }
6522 /.*count(er)?\.(pl|cgi|exe|dll|asp|php[34]?)
6523 /(?:.*/)?(publicite|werbung|rekla(ma|me|am)|annonse|maino(kset|nta|s)?)/
6525 # Site-specific patterns (abbreviated):
6527 .hitbox.com</screen>
6530 It's quite remarkable how many advertisers actually call their banner
6531 servers ads.<replaceable>company</replaceable>.com, or call the directory
6532 in which the banners are stored literally <quote>banners</quote>. So the above
6533 generic patterns are surprisingly effective.
6536 But being very generic, they necessarily also catch URLs that we don't want
6537 to block. The pattern <literal>.*ads.</literal> e.g. catches
6538 <quote>nasty-<emphasis>ads</emphasis>.nasty-corp.com</quote> as intended,
6539 but also <quote>downlo<emphasis>ads</emphasis>.sourcefroge.net</quote> or
6540 <quote><emphasis>ads</emphasis>l.some-provider.net.</quote> So here come some
6541 well-known exceptions to the <literal>+<link linkend="BLOCK">block</link></literal>
6545 Note that these are exceptions to exceptions from the default! Consider the URL
6546 <quote>downloads.sourcefroge.net</quote>: Initially, all actions are deactivated,
6547 so it wouldn't get blocked. Then comes the defaults section, which matches the
6548 URL, but just deactivates the <literal><link linkend="BLOCK">block</link></literal>
6549 action once again. Then it matches <literal>.*ads.</literal>, an exception to the
6550 general non-blocking policy, and suddenly
6551 <literal><link linkend="BLOCK">+block</link></literal> applies. And now, it'll match
6552 <literal>.*loads.</literal>, where <literal><link linkend="BLOCK">-block</link></literal>
6553 applies, so (unless it matches <emphasis>again</emphasis> further down) it ends up
6554 with no <literal><link linkend="BLOCK">block</link></literal> action applying.
6558 ##########################################################################
6559 # Save some innocent victims of the above generic block patterns:
6560 ##########################################################################
6564 { -<link linkend="BLOCK">block</link> }
6565 adv[io]*. # (for advogato.org and advice.*)
6566 adsl. # (has nothing to do with ads)
6567 adobe. # (has nothing to do with ads either)
6568 ad[ud]*. # (adult.* and add.*)
6569 .edu # (universities don't host banners (yet!))
6570 .*loads. # (downloads, uploads etc)
6578 www.globalintersec.com/adv # (adv = advanced)
6579 www.ugu.com/sui/ugu/adv</screen>
6582 Filtering source code can have nasty side effects,
6583 so make an exception for our friends at sourceforge.net,
6584 and all paths with <quote>cvs</quote> in them. Note that
6585 <literal>-<link linkend="FILTER">filter</link></literal>
6586 disables <emphasis>all</emphasis> filters in one fell swoop!
6590 # Don't filter code!
6592 { -<link linkend="FILTER">filter</link> }
6597 .sourceforge.net</screen>
6600 The actual <filename>default.action</filename> is of course much more
6601 comprehensive, but we hope this example made clear how it works.
6606 <sect3 id="user-action"><title>user.action</title>
6609 So far we are painting with a broad brush by setting general policies,
6610 which would be a reasonable starting point for many people. Now,
6611 you might want to be more specific and have customized rules that
6612 are more suitable to your personal habits and preferences. These would
6613 be for narrowly defined situations like your ISP or your bank, and should
6614 be placed in <filename>user.action</filename>, which is parsed after all other
6615 actions files and hence has the last word, over-riding any previously
6616 defined actions. <filename>user.action</filename> is also a
6617 <emphasis>safe</emphasis> place for your personal settings, since
6618 <filename>default.action</filename> is actively maintained by the
6619 <application>Privoxy</application> developers and you'll probably want
6620 to install updated versions from time to time.
6624 So let's look at a few examples of things that one might typically do in
6625 <filename>user.action</filename>:
6629 <!-- brief sample user.action here -->
6632 # My user.action file. <fred@example.com></screen>
6635 As <link linkend="aliases">aliases</link> are local to the actions
6636 file that they are defined in, you can't use the ones from
6637 <filename>default.action</filename>, unless you repeat them here:
6641 # Aliases are local to the file they are defined in.
6642 # (Re-)define aliases for this file:
6646 # These aliases just save typing later, and the alias names should
6647 # be self explanatory.
6649 +crunch-all-cookies = +crunch-incoming-cookies +crunch-outgoing-cookies
6650 -crunch-all-cookies = -crunch-incoming-cookies -crunch-outgoing-cookies
6651 allow-all-cookies = -crunch-all-cookies -session-cookies-only
6652 allow-popups = -filter{all-popups}
6653 +block-as-image = +block{Blocked as image.} +handle-as-image
6654 -block-as-image = -block
6656 # These aliases define combinations of actions that are useful for
6657 # certain types of sites:
6659 fragile = -block -crunch-all-cookies -filter -fast-redirects -hide-referrer
6660 shop = -crunch-all-cookies allow-popups
6662 # Allow ads for selected useful free sites:
6664 allow-ads = -block -filter{banners-by-size} -filter{banners-by-link}
6666 # Alias for specific file types that are text, but might have conflicting
6667 # MIME types. We want the browser to force these to be text documents.
6668 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>
6671 Say you have accounts on some sites that you visit regularly, and
6672 you don't want to have to log in manually each time. So you'd like
6673 to allow persistent cookies for these sites. The
6674 <literal>allow-all-cookies</literal> alias defined above does exactly
6675 that, i.e. it disables crunching of cookies in any direction, and the
6676 processing of cookies to make them only temporary.
6680 { allow-all-cookies }
6684 .redhat.com</screen>
6687 Your bank is allergic to some filter, but you don't know which, so you disable them all:
6691 { -<link linkend="FILTER">filter</link> }
6692 .your-home-banking-site.com</screen>
6695 Some file types you may not want to filter for various reasons:
6699 # Technical documentation is likely to contain strings that might
6700 # erroneously get altered by the JavaScript-oriented filters:
6705 # And this stupid host sends streaming video with a wrong MIME type,
6706 # so that Privoxy thinks it is getting HTML and starts filtering:
6708 stupid-server.example.com/</screen>
6711 Example of a simple <link linkend="BLOCK">block</link> action. Say you've
6712 seen an ad on your favourite page on example.com that you want to get rid of.
6713 You have right-clicked the image, selected <quote>copy image location</quote>
6714 and pasted the URL below while removing the leading http://, into a
6715 <literal>{ +block{} }</literal> section. Note that <literal>{ +handle-as-image
6716 }</literal> need not be specified, since all URLs ending in
6717 <literal>.gif</literal> will be tagged as images by the general rules as set
6718 in default.action anyway:
6722 { +<link linkend="BLOCK">block</link>{Nasty ads.} }
6723 www.example.com/nasty-ads/sponsor\.gif
6724 another.example.net/more/junk/here/</screen>
6727 The URLs of dynamically generated banners, especially from large banner
6728 farms, often don't use the well-known image file name extensions, which
6729 makes it impossible for <application>Privoxy</application> to guess
6730 the file type just by looking at the URL.
6731 You can use the <literal>+block-as-image</literal> alias defined above for
6733 Note that objects which match this rule but then turn out NOT to be an
6734 image are typically rendered as a <quote>broken image</quote> icon by the
6735 browser. Use cautiously.
6743 ar.atwola.com/</screen>
6746 Now you noticed that the default configuration breaks Forbes Magazine,
6747 but you were too lazy to find out which action is the culprit, and you
6748 were again too lazy to give <link linkend="contact">feedback</link>, so
6749 you just used the <literal>fragile</literal> alias on the site, and
6750 -- <emphasis>whoa!</emphasis> -- it worked. The <literal>fragile</literal>
6751 aliases disables those actions that are most likely to break a site. Also,
6752 good for testing purposes to see if it is <application>Privoxy</application>
6753 that is causing the problem or not. We later find other regular sites
6754 that misbehave, and add those to our personalized list of troublemakers:
6761 .mybank.com</screen>
6764 You like the <quote>fun</quote> text replacements in <filename>default.filter</filename>,
6765 but it is disabled in the distributed actions file.
6766 So you'd like to turn it on in your private,
6767 update-safe config, once and for all:
6771 { +<link linkend="filter-fun">filter{fun}</link> }
6772 / # For ALL sites!</screen>
6775 Note that the above is not really a good idea: There are exceptions
6776 to the filters in <filename>default.action</filename> for things that
6777 really shouldn't be filtered, like code on CVS->Web interfaces. Since
6778 <filename>user.action</filename> has the last word, these exceptions
6779 won't be valid for the <quote>fun</quote> filtering specified here.
6783 You might also worry about how your favourite free websites are
6784 funded, and find that they rely on displaying banner advertisements
6785 to survive. So you might want to specifically allow banners for those
6786 sites that you feel provide value to you:
6796 Note that <literal>allow-ads</literal> has been aliased to
6797 <literal>-<link linkend="block">block</link></literal>,
6798 <literal>-<link linkend="filter-banners-by-size">filter{banners-by-size}</link></literal>, and
6799 <literal>-<link linkend="filter-banners-by-link">filter{banners-by-link}</link></literal> above.
6803 Invoke another alias here to force an over-ride of the MIME type <literal>
6804 application/x-sh</literal> which typically would open a download type
6805 dialog. In my case, I want to look at the shell script, and then I can save
6806 it should I choose to.
6814 <filename>user.action</filename> is generally the best place to define
6815 exceptions and additions to the default policies of
6816 <filename>default.action</filename>. Some actions are safe to have their
6817 default policies set here though. So let's set a default policy to have a
6818 <quote>blank</quote> image as opposed to the checkerboard pattern for
6819 <emphasis>ALL</emphasis> sites. <quote>/</quote> of course matches all URL
6824 { +<link linkend="set-image-blocker">set-image-blocker{blank}</link> }
6825 / # ALL sites</screen>
6830 <!-- ~ End section ~ -->
6834 <!-- ~ End section ~ -->
6836 <!-- ~~~~~~~~ New section Header ~~~~~~~~~ -->
6838 <sect1 id="filter-file">
6839 <title>Filter Files</title>
6842 On-the-fly text substitutions need
6843 to be defined in a <quote>filter file</quote>. Once defined, they
6844 can then be invoked as an <quote>action</quote>.
6848 &my-app; supports three different pcrs-based filter actions:
6849 <literal><link linkend="filter">filter</link></literal> to
6850 rewrite the content that is send to the client,
6851 <literal><link linkend="client-header-filter">client-header-filter</link></literal>
6852 to rewrite headers that are send by the client, and
6853 <literal><link linkend="server-header-filter">server-header-filter</link></literal>
6854 to rewrite headers that are send by the server.
6858 &my-app; also supports two tagger actions:
6859 <literal><link linkend="client-header-tagger">client-header-tagger</link></literal>
6861 <literal><link linkend="server-header-tagger">server-header-tagger</link></literal>.
6862 Taggers and filters use the same syntax in the filter files, the difference
6863 is that taggers don't modify the text they are filtering, but use a rewritten
6864 version of the filtered text as tag. The tags can then be used to change the
6865 applying actions through sections with <link linkend="tag-pattern">tag-patterns</link>.
6869 Finally &my-app; supports the
6870 <literal><link linkend="external-filter">external-filter</link></literal> action
6871 to enable <literal><link linkend="external-filter-syntax">external filters</link></literal>
6872 written in proper programming languages.
6877 Multiple filter files can be defined through the <literal> <link
6878 linkend="filterfile">filterfile</link></literal> config directive. The filters
6879 as supplied by the developers are located in
6880 <filename>default.filter</filename>. It is recommended that any locally
6881 defined or modified filters go in a separately defined file such as
6882 <filename>user.filter</filename>.
6886 Common tasks for content filters are to eliminate common annoyances in
6887 HTML and JavaScript, such as pop-up windows,
6888 exit consoles, crippled windows without navigation tools, the
6889 infamous <BLINK> tag etc, to suppress images with certain
6890 width and height attributes (standard banner sizes or web-bugs),
6891 or just to have fun.
6895 Enabled content filters are applied to any content whose
6896 <quote>Content Type</quote> header is recognised as a sign
6897 of text-based content, with the exception of <literal>text/plain</literal>.
6898 Use the <link linkend="FORCE-TEXT-MODE">force-text-mode</link> action
6899 to also filter other content.
6903 Substitutions are made at the source level, so if you want to <quote>roll
6904 your own</quote> filters, you should first be familiar with HTML syntax,
6905 and, of course, regular expressions.
6909 Just like the <link linkend="actions-file">actions files</link>, the
6910 filter file is organized in sections, which are called <emphasis>filters</emphasis>
6911 here. Each filter consists of a heading line, that starts with one of the
6912 <emphasis>keywords</emphasis> <literal>FILTER:</literal>,
6913 <literal>CLIENT-HEADER-FILTER:</literal> or <literal>SERVER-HEADER-FILTER:</literal>
6914 followed by the filter's <emphasis>name</emphasis>, and a short (one line)
6915 <emphasis>description</emphasis> of what it does. Below that line
6916 come the <emphasis>jobs</emphasis>, i.e. lines that define the actual
6917 text substitutions. By convention, the name of a filter
6918 should describe what the filter <emphasis>eliminates</emphasis>. The
6919 comment is used in the <ulink url="http://config.privoxy.org/">web-based
6920 user interface</ulink>.
6924 Once a filter called <replaceable>name</replaceable> has been defined
6925 in the filter file, it can be invoked by using an action of the form
6926 +<literal><link linkend="filter">filter</link>{<replaceable>name</replaceable>}</literal>
6927 in any <link linkend="actions-file">actions file</link>.
6931 Filter definitions start with a header line that contains the filter
6932 type, the filter name and the filter description.
6933 A content filter header line for a filter called <quote>foo</quote> could look
6937 <screen>FILTER: foo Replace all "foo" with "bar"</screen>
6940 Below that line, and up to the next header line, come the jobs that
6941 define what text replacements the filter executes. They are specified
6942 in a syntax that imitates <ulink url="http://www.perl.org/">Perl</ulink>'s
6943 <literal>s///</literal> operator. If you are familiar with Perl, you
6944 will find this to be quite intuitive, and may want to look at the
6945 PCRS documentation for the subtle differences to Perl behaviour.
6949 Most notably, the non-standard option letter <literal>U</literal> is supported,
6950 which turns the default to ungreedy matching (add <literal>?</literal> to
6951 quantifiers to turn them greedy again).
6955 The non-standard option letter <literal>D</literal> (dynamic) allows
6956 to use the variables $host, $origin (the IP address the request came from),
6957 $path, $url and $listen-address (the address on which Privoxy accepted the
6958 client request. Example: 127.0.0.1:8118).
6959 They will be replaced with the value they refer to before the filter
6964 Note that '$' is a bad choice for a delimiter in a dynamic filter as you
6965 might end up with unintended variables if you use a variable name
6966 directly after the delimiter. Variables will be resolved without
6967 escaping anything, therefore you also have to be careful not to chose
6968 delimiters that appear in the replacement text. For example '<' should
6969 be save, while '?' will sooner or later cause conflicts with $url.
6973 The non-standard option letter <literal>T</literal> (trivial) prevents
6974 parsing for backreferences in the substitute. Use it if you want to include
6975 text like '$&' in your substitute without quoting.
6980 <ulink url="http://en.wikipedia.org/wiki/Regular_expressions"><quote>Regular
6981 Expressions</quote></ulink>, you might want to take a look at
6982 the <link linkend="regex">Appendix on regular expressions</link>, and
6983 see the <ulink url="http://perldoc.perl.org/perlre.html">Perl
6985 <ulink url="http://perldoc.perl.org/perlop.html">the
6986 <literal>s///</literal> operator's syntax</ulink> and <ulink
6987 url="http://perldoc.perl.org/perlre.html">Perl-style regular
6988 expressions</ulink> in general.
6989 The below examples might also help to get you started.
6993 <!-- ~~~~~~~~ New section Header ~~~~~~~~~ -->
6995 <sect2 id="filter-file-tut"><title>Filter File Tutorial</title>
6997 Now, let's complete our <quote>foo</quote> content filter. We have already defined
6998 the heading, but the jobs are still missing. Since all it does is to replace
6999 <quote>foo</quote> with <quote>bar</quote>, there is only one (trivial) job
7003 <screen>s/foo/bar/</screen>
7006 But wait! Didn't the comment say that <emphasis>all</emphasis> occurrences
7007 of <quote>foo</quote> should be replaced? Our current job will only take
7008 care of the first <quote>foo</quote> on each page. For global substitution,
7009 we'll need to add the <literal>g</literal> option:
7012 <screen>s/foo/bar/g</screen>
7015 Our complete filter now looks like this:
7018 <screen>FILTER: foo Replace all "foo" with "bar"
7019 s/foo/bar/g</screen>
7022 Let's look at some real filters for more interesting examples. Here you see
7023 a filter that protects against some common annoyances that arise from JavaScript
7024 abuse. Let's look at its jobs one after the other:
7029 FILTER: js-annoyances Get rid of particularly annoying JavaScript abuse
7031 # Get rid of JavaScript referrer tracking. Test page: http://www.randomoddness.com/untitled.htm
7033 s|(<script.*)document\.referrer(.*</script>)|$1"Not Your Business!"$2|Usg</screen>
7036 Following the header line and a comment, you see the job. Note that it uses
7037 <literal>|</literal> as the delimiter instead of <literal>/</literal>, because
7038 the pattern contains a forward slash, which would otherwise have to be escaped
7039 by a backslash (<literal>\</literal>).
7043 Now, let's examine the pattern: it starts with the text <literal><script.*</literal>
7044 enclosed in parentheses. Since the dot matches any character, and <literal>*</literal>
7045 means: <quote>Match an arbitrary number of the element left of myself</quote>, this
7046 matches <quote><script</quote>, followed by <emphasis>any</emphasis> text, i.e.
7047 it matches the whole page, from the start of the first <script> tag.
7051 That's more than we want, but the pattern continues: <literal>document\.referrer</literal>
7052 matches only the exact string <quote>document.referrer</quote>. The dot needed to
7053 be <emphasis>escaped</emphasis>, i.e. preceded by a backslash, to take away its
7054 special meaning as a joker, and make it just a regular dot. So far, the meaning is:
7055 Match from the start of the first <script> tag in a the page, up to, and including,
7056 the text <quote>document.referrer</quote>, if <emphasis>both</emphasis> are present
7057 in the page (and appear in that order).
7061 But there's still more pattern to go. The next element, again enclosed in parentheses,
7062 is <literal>.*</script></literal>. You already know what <literal>.*</literal>
7063 means, so the whole pattern translates to: Match from the start of the first <script>
7064 tag in a page to the end of the last <script> tag, provided that the text
7065 <quote>document.referrer</quote> appears somewhere in between.
7069 This is still not the whole story, since we have ignored the options and the parentheses:
7070 The portions of the page matched by sub-patterns that are enclosed in parentheses, will be
7071 remembered and be available through the variables <literal>$1, $2, ...</literal> in
7072 the substitute. The <literal>U</literal> option switches to ungreedy matching, which means
7073 that the first <literal>.*</literal> in the pattern will only <quote>eat up</quote> all
7074 text in between <quote><script</quote> and the <emphasis>first</emphasis> occurrence
7075 of <quote>document.referrer</quote>, and that the second <literal>.*</literal> will
7076 only span the text up to the <emphasis>first</emphasis> <quote></script></quote>
7077 tag. Furthermore, the <literal>s</literal> option says that the match may span
7078 multiple lines in the page, and the <literal>g</literal> option again means that the
7079 substitution is global.
7083 So, to summarize, the pattern means: Match all scripts that contain the text
7084 <quote>document.referrer</quote>. Remember the parts of the script from
7085 (and including) the start tag up to (and excluding) the string
7086 <quote>document.referrer</quote> as <literal>$1</literal>, and the part following
7087 that string, up to and including the closing tag, as <literal>$2</literal>.
7091 Now the pattern is deciphered, but wasn't this about substituting things? So
7092 lets look at the substitute: <literal>$1"Not Your Business!"$2</literal> is
7093 easy to read: The text remembered as <literal>$1</literal>, followed by
7094 <literal>"Not Your Business!"</literal> (<emphasis>including</emphasis>
7095 the quotation marks!), followed by the text remembered as <literal>$2</literal>.
7096 This produces an exact copy of the original string, with the middle part
7097 (the <quote>document.referrer</quote>) replaced by <literal>"Not Your
7098 Business!"</literal>.
7102 The whole job now reads: Replace <quote>document.referrer</quote> by
7103 <literal>"Not Your Business!"</literal> wherever it appears inside a
7104 <script> tag. Note that this job won't break JavaScript syntax,
7105 since both the original and the replacement are syntactically valid
7106 string objects. The script just won't have access to the referrer
7107 information anymore.
7111 We'll show you two other jobs from the JavaScript taming department, but
7112 this time only point out the constructs of special interest:
7116 # The status bar is for displaying link targets, not pointless blahblah
7118 s/window\.status\s*=\s*(['"]).*?\1/dUmMy=1/ig</screen>
7121 <literal>\s</literal> stands for whitespace characters (space, tab, newline,
7122 carriage return, form feed), so that <literal>\s*</literal> means: <quote>zero
7123 or more whitespace</quote>. The <literal>?</literal> in <literal>.*?</literal>
7124 makes this matching of arbitrary text ungreedy. (Note that the <literal>U</literal>
7125 option is not set). The <literal>['"]</literal> construct means: <quote>a single
7126 <emphasis>or</emphasis> a double quote</quote>. Finally, <literal>\1</literal> is
7127 a back-reference to the first parenthesis just like <literal>$1</literal> above,
7128 with the difference that in the <emphasis>pattern</emphasis>, a backslash indicates
7129 a back-reference, whereas in the <emphasis>substitute</emphasis>, it's the dollar.
7133 So what does this job do? It replaces assignments of single- or double-quoted
7134 strings to the <quote>window.status</quote> object with a dummy assignment
7135 (using a variable name that is hopefully odd enough not to conflict with
7136 real variables in scripts). Thus, it catches many cases where e.g. pointless
7137 descriptions are displayed in the status bar instead of the link target when
7138 you move your mouse over links.
7142 # Kill OnUnload popups. Yummy. Test: http://www.zdnet.com/zdsubs/yahoo/tree/yfs.html
7144 s/(<body [^>]*)onunload(.*>)/$1never$2/iU</screen>
7148 <ulink url="http://www.w3.org/TR/2000/REC-DOM-Level-2-Events-20001113/events.html#Events-eventgroupings-htmlevents">OnUnload
7149 event binding</ulink> in the HTML DOM was a <emphasis>CRIME</emphasis>.
7150 When I close a browser window, I want it to close and die. Basta.
7151 This job replaces the <quote>onunload</quote> attribute in
7152 <quote><body></quote> tags with the dummy word <literal>never</literal>.
7153 Note that the <literal>i</literal> option makes the pattern matching
7154 case-insensitive. Also note that ungreedy matching alone doesn't always guarantee
7155 a minimal match: In the first parenthesis, we had to use <literal>[^>]*</literal>
7156 instead of <literal>.*</literal> to prevent the match from exceeding the
7157 <body> tag if it doesn't contain <quote>OnUnload</quote>, but the page's
7162 The last example is from the fun department:
7166 FILTER: fun Fun text replacements
7168 # Spice the daily news:
7170 s/microsoft(?!\.com)/MicroSuck/ig</screen>
7173 Note the <literal>(?!\.com)</literal> part (a so-called negative lookahead)
7174 in the job's pattern, which means: Don't match, if the string
7175 <quote>.com</quote> appears directly following <quote>microsoft</quote>
7176 in the page. This prevents links to microsoft.com from being trashed, while
7177 still replacing the word everywhere else.
7181 # Buzzword Bingo (example for extended regex syntax)
7183 s* industry[ -]leading \
7185 | customer[ -]focused \
7186 | market[ -]driven \
7187 | award[ -]winning # Comments are OK, too! \
7188 | high[ -]performance \
7189 | solutions[ -]based \
7193 *<font color="red"><b>BINGO!</b></font> \
7197 The <literal>x</literal> option in this job turns on extended syntax, and allows for
7198 e.g. the liberal use of (non-interpreted!) whitespace for nicer formatting.
7206 <!-- ~~~~~~~~ New section Header ~~~~~~~~~ -->
7208 <sect2 id="predefined-filters"><title>The Pre-defined Filters</title>
7212 Note each filter is also listed in the +filter action section above. Please
7213 keep these listings in sync.
7218 The distribution <filename>default.filter</filename> file contains a selection of
7219 pre-defined filters for your convenience:
7224 <term><emphasis>js-annoyances</emphasis></term>
7227 The purpose of this filter is to get rid of particularly annoying JavaScript abuse.
7233 replaces JavaScript references to the browser's referrer information
7234 with the string "Not Your Business!". This compliments the <literal><link
7235 linkend="hide-referrer">hide-referrer</link></literal> action on the content level.
7240 removes the bindings to the DOM's
7241 <ulink url="http://www.w3.org/TR/2000/REC-DOM-Level-2-Events-20001113/events.html#Events-eventgroupings-htmlevents">unload
7242 event</ulink> which we feel has no right to exist and is responsible for most <quote>exit consoles</quote>, i.e.
7243 nasty windows that pop up when you close another one.
7248 removes code that causes new windows to be opened with undesired properties, such as being
7249 full-screen, non-resizeable, without location, status or menu bar etc.
7254 Use with caution. This is an aggressive filter, and can break sites that
7255 rely heavily on JavaScript.
7261 <term><emphasis>js-events</emphasis></term>
7264 This is a very radical measure. It removes virtually all JavaScript event bindings, which
7265 means that scripts can not react to user actions such as mouse movements or clicks, window
7266 resizing etc, anymore. Use with caution!
7269 We <emphasis>strongly discourage</emphasis> using this filter as a default since it breaks
7270 many legitimate scripts. It is meant for use only on extra-nasty sites (should you really
7277 <term><emphasis>html-annoyances</emphasis></term>
7280 This filter will undo many common instances of HTML based abuse.
7283 The <literal>BLINK</literal> and <literal>MARQUEE</literal> tags
7284 are neutralized (yeah baby!), and browser windows will be created as
7285 resizeable (as of course they should be!), and will have location,
7286 scroll and menu bars -- even if specified otherwise.
7292 <term><emphasis>content-cookies</emphasis></term>
7295 Most cookies are set in the HTTP dialog, where they can be intercepted
7297 <literal><link linkend="crunch-incoming-cookies">crunch-incoming-cookies</link></literal>
7298 and <literal><link linkend="crunch-outgoing-cookies">crunch-outgoing-cookies</link></literal>
7299 actions. But web sites increasingly make use of HTML meta tags and JavaScript
7300 to sneak cookies to the browser on the content level.
7303 This filter disables most HTML and JavaScript code that reads or sets
7304 cookies. It cannot detect all clever uses of these types of code, so it
7305 should not be relied on as an absolute fix. Use it wherever you would also
7306 use the cookie crunch actions.
7312 <term><emphasis>refresh-tags</emphasis></term>
7315 Disable any refresh tags if the interval is greater than nine seconds (so
7316 that redirections done via refresh tags are not destroyed). This is useful
7317 for dial-on-demand setups, or for those who find this HTML feature
7324 <term><emphasis>unsolicited-popups</emphasis></term>
7327 This filter attempts to prevent only <quote>unsolicited</quote> pop-up
7328 windows from opening, yet still allow pop-up windows that the user
7329 has explicitly chosen to open. It was added in version 3.0.1,
7330 as an improvement over earlier such filters.
7333 Technical note: The filter works by redefining the window.open JavaScript
7334 function to a dummy function, <literal>PrivoxyWindowOpen()</literal>,
7335 during the loading and rendering phase of each HTML page access, and
7336 restoring the function afterward.
7339 This is recommended only for browsers that cannot perform this function
7340 reliably themselves. And be aware that some sites require such windows
7341 in order to function normally. Use with caution.
7347 <term><emphasis>all-popups</emphasis></term>
7350 Attempt to prevent <emphasis>all</emphasis> pop-up windows from opening.
7351 Note this should be used with even more discretion than the above, since
7352 it is more likely to break some sites that require pop-ups for normal
7353 usage. Use with caution.
7359 <term><emphasis>img-reorder</emphasis></term>
7362 This is a helper filter that has no value if used alone. It makes the
7363 <literal>banners-by-size</literal> and <literal>banners-by-link</literal>
7364 (see below) filters more effective and should be enabled together with them.
7370 <term><emphasis>banners-by-size</emphasis></term>
7373 This filter removes image tags purely based on what size they are. Fortunately
7374 for us, many ads and banner images tend to conform to certain standardized
7375 sizes, which makes this filter quite effective for ad stripping purposes.
7378 Occasionally this filter will cause false positives on images that are not ads,
7379 but just happen to be of one of the standard banner sizes.
7382 Recommended only for those who require extreme ad blocking. The default
7383 block rules should catch 95+% of all ads <emphasis>without</emphasis> this filter enabled.
7389 <term><emphasis>banners-by-link</emphasis></term>
7392 This is an experimental filter that attempts to kill any banners if
7393 their URLs seem to point to known or suspected click trackers. It is currently
7394 not of much value and is not recommended for use by default.
7400 <term><emphasis>webbugs</emphasis></term>
7403 Webbugs are small, invisible images (technically 1X1 GIF images), that
7404 are used to track users across websites, and collect information on them.
7405 As an HTML page is loaded by the browser, an embedded image tag causes the
7406 browser to contact a third-party site, disclosing the tracking information
7407 through the requested URL and/or cookies for that third-party domain, without
7408 the user ever becoming aware of the interaction with the third-party site.
7409 HTML-ized spam also uses a similar technique to verify email addresses.
7412 This filter removes the HTML code that loads such <quote>webbugs</quote>.
7418 <term><emphasis>tiny-textforms</emphasis></term>
7421 A rather special-purpose filter that can be used to enlarge textareas (those
7422 multi-line text boxes in web forms) and turn off hard word wrap in them.
7423 It was written for the sourceforge.net tracker system where such boxes are
7424 a nuisance, but it can be handy on other sites, too.
7427 It is not recommended to use this filter as a default.
7433 <term><emphasis>jumping-windows</emphasis></term>
7436 Many consider windows that move, or resize themselves to be abusive. This filter
7437 neutralizes the related JavaScript code. Note that some sites might not display
7438 or behave as intended when using this filter. Use with caution.
7444 <term><emphasis>frameset-borders</emphasis></term>
7447 Some web designers seem to assume that everyone in the world will view their
7448 web sites using the same browser brand and version, screen resolution etc,
7449 because only that assumption could explain why they'd use static frame sizes,
7450 yet prevent their frames from being resized by the user, should they be too
7451 small to show their whole content.
7454 This filter removes the related HTML code. It should only be applied to sites
7461 <term><emphasis>demoronizer</emphasis></term>
7464 Many Microsoft products that generate HTML use non-standard extensions (read:
7465 violations) of the ISO 8859-1 aka Latin-1 character set. This can cause those
7466 HTML documents to display with errors on standard-compliant platforms.
7469 This filter translates the MS-only characters into Latin-1 equivalents.
7470 It is not necessary when using MS products, and will cause corruption of
7471 all documents that use 8-bit character sets other than Latin-1. It's mostly
7472 worthwhile for Europeans on non-MS platforms, if weird garbage characters
7473 sometimes appear on some pages, or user agents that don't correct for this on
7476 My version of Mozilla (ancient) shows litte square boxes for quote
7477 characters, and apostrophes on moronized pages. So many pages have this, I
7478 can read them fine now. HB 08/27/06
7485 <term><emphasis>shockwave-flash</emphasis></term>
7488 A filter for shockwave haters. As the name suggests, this filter strips code
7489 out of web pages that is used to embed shockwave flash objects.
7497 <term><emphasis>quicktime-kioskmode</emphasis></term>
7500 Change HTML code that embeds Quicktime objects so that kioskmode, which
7501 prevents saving, is disabled.
7507 <term><emphasis>fun</emphasis></term>
7510 Text replacements for subversive browsing fun. Make fun of your favorite
7511 Monopolist or play buzzword bingo.
7517 <term><emphasis>crude-parental</emphasis></term>
7520 A demonstration-only filter that shows how <application>Privoxy</application>
7521 can be used to delete web content on a keyword basis.
7527 <term><emphasis>ie-exploits</emphasis></term>
7530 An experimental collection of text replacements to disable malicious HTML and JavaScript
7531 code that exploits known security holes in Internet Explorer.
7534 Presently, it only protects against Nimda and a cross-site scripting bug, and
7535 would need active maintenance to provide more substantial protection.
7541 <term><emphasis>site-specifics</emphasis></term>
7544 Some web sites have very specific problems, the cure for which doesn't apply
7545 anywhere else, or could even cause damage on other sites.
7548 This is a collection of such site-specific cures which should only be applied
7549 to the sites they were intended for, which is what the supplied
7550 <filename>default.action</filename> file does. Users shouldn't need to change
7551 anything regarding this filter.
7557 <term><emphasis>google</emphasis></term>
7560 A CSS based block for Google text ads. Also removes a width limitation
7561 and the toolbar advertisement.
7567 <term><emphasis>yahoo</emphasis></term>
7570 Another CSS based block, this time for Yahoo text ads. And removes
7571 a width limitation as well.
7577 <term><emphasis>msn</emphasis></term>
7580 Another CSS based block, this time for MSN text ads. And removes
7581 tracking URLs, as well as a width limitation.
7587 <term><emphasis>blogspot</emphasis></term>
7590 Cleans up some Blogspot blogs. Read the fine print before using this one!
7593 This filter also intentionally removes some navigation stuff and sets the
7594 page width to 100%. As a result, some rounded <quote>corners</quote> would
7595 appear to early or not at all and as fixing this would require a browser
7596 that understands background-size (CSS3), they are removed instead.
7602 <term><emphasis>xml-to-html</emphasis></term>
7605 Server-header filter to change the Content-Type from xml to html.
7611 <term><emphasis>html-to-xml</emphasis></term>
7614 Server-header filter to change the Content-Type from html to xml.
7620 <term><emphasis>no-ping</emphasis></term>
7623 Removes the non-standard <literal>ping</literal> attribute from
7624 anchor and area HTML tags.
7630 <term><emphasis>hide-tor-exit-notation</emphasis></term>
7633 Client-header filter to remove the <command>Tor</command> exit node notation
7634 found in Host and Referer headers.
7637 If &my-app; and <command>Tor</command> are chained and &my-app;
7638 is configured to use socks4a, one can use <quote>http://www.example.org.foobar.exit/</quote>
7639 to access the host <quote>www.example.org</quote> through the
7640 <command>Tor</command> exit node <quote>foobar</quote>.
7643 As the HTTP client isn't aware of this notation, it treats the
7644 whole string <quote>www.example.org.foobar.exit</quote> as host and uses it
7645 for the <quote>Host</quote> and <quote>Referer</quote> headers. From the
7646 server's point of view the resulting headers are invalid and can cause problems.
7649 An invalid <quote>Referer</quote> header can trigger <quote>hot-linking</quote>
7650 protections, an invalid <quote>Host</quote> header will make it impossible for
7651 the server to find the right vhost (several domains hosted on the same IP address).
7654 This client-header filter removes the <quote>foo.exit</quote> part in those headers
7655 to prevent the mentioned problems. Note that it only modifies
7656 the HTTP headers, it doesn't make it impossible for the server
7657 to detect your <command>Tor</command> exit node based on the IP address
7658 the request is coming from.
7665 <term><emphasis> </emphasis></term>
7678 <!-- ~~~~~~~~ New section Header ~~~~~~~~~ -->
7679 <sect2 id="external-filter-syntax"><title>External filter syntax</title>
7681 External filters are scripts or programs that can modify the content in
7682 case common <literal><link linkend="filter">filters</link></literal>
7683 aren't powerful enough.
7686 External filters can be written in any language the platform &my-app; runs
7690 They are controlled with the
7691 <literal><link linkend="external-filter">external-filter</link></literal> action
7692 and have to be defined in the <literal><link linkend="filterfile">filterfile</link></literal>
7696 The header looks like any other filter, but instead of pcrs jobs, external
7697 filters contain a single job which can be a program or a shell script (which
7698 may call other scripts or programs).
7701 External filters read the content from STDIN and write the rewritten
7703 The environment variables PRIVOXY_URL, PRIVOXY_PATH, PRIVOXY_HOST,
7704 PRIVOXY_ORIGIN, PRIVOXY_LISTEN_ADDRESS can be used to get some details
7705 about the client request.
7708 &my-app; will temporary store the content to filter in the
7709 <literal><link linkend="temporary-directory">temporary-directory</link></literal>.
7713 EXTERNAL-FILTER: cat Pointless example filter that doesn't actually modify the content
7716 # Incorrect reimplementation of the filter above in POSIX shell.
7718 # Note that it's a single job that spans multiple lines, the line
7719 # breaks are not passed to the shell, thus the semicolons are required.
7721 # If the script isn't trivial, it is recommended to put it into an external file.
7723 # In general, writing external filters entirely in POSIX shell is not
7724 # considered a good idea.
7725 EXTERNAL-FILTER: cat2 Pointless example filter that despite its name may actually modify the content
7731 EXTERNAL-FILTER: rotate-image Rotate an image by 180 degree. Test filter with limited value.
7732 /usr/local/bin/convert - -rotate 180 -
7734 EXTERNAL-FILTER: citation-needed Adds a "[citation needed]" tag to an image. The coordinates may need adjustment.
7735 /usr/local/bin/convert - -pointsize 16 -fill white -annotate +17+418 "[citation needed]" -
7740 Currently external filters are executed with &my-app;'s privileges!
7741 Only use external filters you understand and trust.
7745 External filters are experimental and the syntax may change in the future.
7751 <!-- ~ End section ~ -->
7755 <!-- ~~~~~ New section ~~~~~ -->
7757 <sect1 id="templates">
7758 <title>Privoxy's Template Files</title>
7760 All <application>Privoxy</application> built-in pages, i.e. error pages such as the
7761 <ulink url="http://show-the-404-error.page"><quote>404 - No Such Domain</quote>
7762 error page</ulink>, the <ulink
7763 url="http://ads.bannerserver.example.com/nasty-ads/sponsor.html"><quote>BLOCKED</quote>
7765 and all pages of its <ulink url="http://config.privoxy.org/">web-based
7766 user interface</ulink>, are generated from <emphasis>templates</emphasis>.
7767 (<application>Privoxy</application> must be running for the above links to work as
7772 These templates are stored in a subdirectory of the <link linkend="confdir">configuration
7773 directory</link> called <filename>templates</filename>. On Unixish platforms,
7775 <ulink url="file:///etc/privoxy/templates/"><filename>/etc/privoxy/templates/</filename></ulink>.
7779 The templates are basically normal HTML files, but with place-holders (called symbols
7780 or exports), which <application>Privoxy</application> fills at run time. It
7781 is possible to edit the templates with a normal text editor, should you want
7782 to customize them. (<emphasis>Not recommended for the casual
7783 user</emphasis>). Should you create your own custom templates, you should use
7784 the <filename>config</filename> setting <link linkend="templdir">templdir</link>
7785 to specify an alternate location, so your templates do not get overwritten
7789 Note that just like in configuration files, lines starting
7790 with <literal>#</literal> are ignored when the templates are filled in.
7794 The place-holders are of the form <literal>@name@</literal>, and you will
7795 find a list of available symbols, which vary from template to template,
7796 in the comments at the start of each file. Note that these comments are not
7797 always accurate, and that it's probably best to look at the existing HTML
7798 code to find out which symbols are supported and what they are filled in with.
7802 A special application of this substitution mechanism is to make whole
7803 blocks of HTML code disappear when a specific symbol is set. We use this
7804 for many purposes, one of them being to include the beta warning in all
7805 our user interface (CGI) pages when <application>Privoxy</application>
7806 is in an alpha or beta development stage:
7810 <!-- @if-unstable-start -->
7812 ... beta warning HTML code goes here ...
7814 <!-- if-unstable-end@ --></screen>
7817 If the "unstable" symbol is set, everything in between and including
7818 <literal>@if-unstable-start</literal> and <literal>if-unstable-end@</literal>
7819 will disappear, leaving nothing but an empty comment:
7822 <screen><!-- --></screen>
7825 There's also an if-then-else construct and an <literal>#include</literal>
7826 mechanism, but you'll sure find out if you are inclined to edit the
7831 All templates refer to a style located at
7832 <ulink url="http://config.privoxy.org/send-stylesheet"><literal>http://config.privoxy.org/send-stylesheet</literal></ulink>.
7833 This is, of course, locally served by <application>Privoxy</application>
7834 and the source for it can be found and edited in the
7835 <filename>cgi-style.css</filename> template.
7840 <!-- ~ End section ~ -->
7844 <!-- ~~~~~ New section ~~~~~ -->
7846 <sect1 id="contact"><title>Contacting the Developers, Bug Reporting and Feature
7849 <!-- Include contacting.sgml boilerplate: -->
7851 <!-- end boilerplate -->
7855 <!-- ~ End section ~ -->
7858 <!-- ~~~~~ New section ~~~~~ -->
7859 <sect1 id="copyright"><title>Privoxy Copyright, License and History</title>
7861 <!-- Include copyright.sgml: -->
7863 <!-- end copyright -->
7866 <application>Privoxy</application> is free software; you can
7867 redistribute it and/or modify it under the terms of the
7868 <citetitle>GNU General Public License</citetitle>, version 2,
7869 as published by the Free Software Foundation and included in
7873 <!-- ~~~~~ New section ~~~~~ -->
7874 <sect2 id="license"><title>License</title>
7876 <screen><![ RCDATA [ &GPLv2; ]]></screen>
7879 <!-- ~ End section ~ -->
7882 <!-- ~~~~~ New section ~~~~~ -->
7884 <sect2 id="history"><title>History</title>
7885 <!-- Include history.sgml: -->
7887 <!-- end history -->
7890 <sect2 id="authors"><title>Authors</title>
7891 <!-- Include p-authors.sgml: -->
7893 <!-- end authors -->
7898 <!-- ~ End section ~ -->
7901 <!-- ~~~~~ New section ~~~~~ -->
7902 <sect1 id="seealso"><title>See Also</title>
7903 <!-- Include seealso.sgml: -->
7905 <!-- end seealso -->
7910 <!-- ~~~~~ New section ~~~~~ -->
7911 <sect1 id="appendix"><title>Appendix</title>
7914 <!-- ~~~~~ New section ~~~~~ -->
7916 <title>Regular Expressions</title>
7918 <application>Privoxy</application> uses Perl-style <quote>regular
7919 expressions</quote> in its <link linkend="actions-file">actions
7920 files</link> and <link linkend="filter-file">filter file</link>,
7921 through the <ulink url="http://www.pcre.org/">PCRE</ulink> and
7924 <ulink url="http://www.oesterhelt.org/pcrs/">PCRS</ulink> libraries.
7926 <application>PCRS</application> libraries.
7930 If you are reading this, you probably don't understand what <quote>regular
7931 expressions</quote> are, or what they can do. So this will be a very brief
7932 introduction only. A full explanation would require a <ulink
7933 url="http://www.oreilly.com/catalog/regex/">book</ulink> ;-)
7937 Regular expressions provide a language to describe patterns that can be
7938 run against strings of characters (letter, numbers, etc), to see if they
7939 match the string or not. The patterns are themselves (sometimes complex)
7940 strings of literal characters, combined with wild-cards, and other special
7941 characters, called meta-characters. The <quote>meta-characters</quote> have
7942 special meanings and are used to build complex patterns to be matched against.
7943 Perl Compatible Regular Expressions are an especially convenient
7944 <quote>dialect</quote> of the regular expression language.
7948 To make a simple analogy, we do something similar when we use wild-card
7949 characters when listing files with the <command>dir</command> command in DOS.
7950 <literal>*.*</literal> matches all filenames. The <quote>special</quote>
7951 character here is the asterisk which matches any and all characters. We can be
7952 more specific and use <literal>?</literal> to match just individual
7953 characters. So <quote>dir file?.text</quote> would match
7954 <quote>file1.txt</quote>, <quote>file2.txt</quote>, etc. We are pattern
7955 matching, using a similar technique to <quote>regular expressions</quote>!
7959 Regular expressions do essentially the same thing, but are much, much more
7960 powerful. There are many more <quote>special characters</quote> and ways of
7961 building complex patterns however. Let's look at a few of the common ones,
7962 and then some examples:
7967 <emphasis>.</emphasis> - Matches any single character, e.g. <quote>a</quote>,
7968 <quote>A</quote>, <quote>4</quote>, <quote>:</quote>, or <quote>@</quote>.
7974 <emphasis>?</emphasis> - The preceding character or expression is matched ZERO or ONE
7981 <emphasis>+</emphasis> - The preceding character or expression is matched ONE or MORE
7988 <emphasis>*</emphasis> - The preceding character or expression is matched ZERO or MORE
7995 <emphasis>\</emphasis> - The <quote>escape</quote> character denotes that
7996 the following character should be taken literally. This is used where one of the
7997 special characters (e.g. <quote>.</quote>) needs to be taken literally and
7998 not as a special meta-character. Example: <quote>example\.com</quote>, makes
7999 sure the period is recognized only as a period (and not expanded to its
8000 meta-character meaning of any single character).
8006 <emphasis>[ ]</emphasis> - Characters enclosed in brackets will be matched if
8007 any of the enclosed characters are encountered. For instance, <quote>[0-9]</quote>
8008 matches any numeric digit (zero through nine). As an example, we can combine
8009 this with <quote>+</quote> to match any digit one of more times: <quote>[0-9]+</quote>.
8015 <emphasis>( )</emphasis> - parentheses are used to group a sub-expression,
8016 or multiple sub-expressions.
8022 <emphasis>|</emphasis> - The <quote>bar</quote> character works like an
8023 <quote>or</quote> conditional statement. A match is successful if the
8024 sub-expression on either side of <quote>|</quote> matches. As an example:
8025 <quote>/(this|that) example/</quote> uses grouping and the bar character
8026 and would match either <quote>this example</quote> or <quote>that
8027 example</quote>, and nothing else.
8032 These are just some of the ones you are likely to use when matching URLs with
8033 <application>Privoxy</application>, and is a long way from a definitive
8034 list. This is enough to get us started with a few simple examples which may
8035 be more illuminating:
8039 <emphasis><literal>/.*/banners/.*</literal></emphasis> - A simple example
8040 that uses the common combination of <quote>.</quote> and <quote>*</quote> to
8041 denote any character, zero or more times. In other words, any string at all.
8042 So we start with a literal forward slash, then our regular expression pattern
8043 (<quote>.*</quote>) another literal forward slash, the string
8044 <quote>banners</quote>, another forward slash, and lastly another
8045 <quote>.*</quote>. We are building
8046 a directory path here. This will match any file with the path that has a
8047 directory named <quote>banners</quote> in it. The <quote>.*</quote> matches
8048 any characters, and this could conceivably be more forward slashes, so it
8049 might expand into a much longer looking path. For example, this could match:
8050 <quote>/eye/hate/spammers/banners/annoy_me_please.gif</quote>, or just
8051 <quote>/banners/annoying.html</quote>, or almost an infinite number of other
8052 possible combinations, just so it has <quote>banners</quote> in the path
8057 And now something a little more complex:
8061 <emphasis><literal>/.*/adv((er)?ts?|ertis(ing|ements?))?/</literal></emphasis> -
8062 We have several literal forward slashes again (<quote>/</quote>), so we are
8063 building another expression that is a file path statement. We have another
8064 <quote>.*</quote>, so we are matching against any conceivable sub-path, just so
8065 it matches our expression. The only true literal that <emphasis>must
8066 match</emphasis> our pattern is <application>adv</application>, together with
8067 the forward slashes. What comes after the <quote>adv</quote> string is the
8072 Remember the <quote>?</quote> means the preceding expression (either a
8073 literal character or anything grouped with <quote>(...)</quote> in this case)
8074 can exist or not, since this means either zero or one match. So
8075 <quote>((er)?ts?|ertis(ing|ements?))</quote> is optional, as are the
8076 individual sub-expressions: <quote>(er)</quote>,
8077 <quote>(ing|ements?)</quote>, and the <quote>s</quote>. The <quote>|</quote>
8078 means <quote>or</quote>. We have two of those. For instance,
8079 <quote>(ing|ements?)</quote>, can expand to match either <quote>ing</quote>
8080 <emphasis>OR</emphasis> <quote>ements?</quote>. What is being done here, is an
8081 attempt at matching as many variations of <quote>advertisement</quote>, and
8082 similar, as possible. So this would expand to match just <quote>adv</quote>,
8083 or <quote>advert</quote>, or <quote>adverts</quote>, or
8084 <quote>advertising</quote>, or <quote>advertisement</quote>, or
8085 <quote>advertisements</quote>. You get the idea. But it would not match
8086 <quote>advertizements</quote> (with a <quote>z</quote>). We could fix that by
8087 changing our regular expression to:
8088 <quote>/.*/adv((er)?ts?|erti(s|z)(ing|ements?))?/</quote>, which would then match
8093 <emphasis><literal>/.*/advert[0-9]+\.(gif|jpe?g)</literal></emphasis> - Again
8094 another path statement with forward slashes. Anything in the square brackets
8095 <quote>[ ]</quote> can be matched. This is using <quote>0-9</quote> as a
8096 shorthand expression to mean any digit one through nine. It is the same as
8097 saying <quote>0123456789</quote>. So any digit matches. The <quote>+</quote>
8098 means one or more of the preceding expression must be included. The preceding
8099 expression here is what is in the square brackets -- in this case, any digit
8100 one through nine. Then, at the end, we have a grouping: <quote>(gif|jpe?g)</quote>.
8101 This includes a <quote>|</quote>, so this needs to match the expression on
8102 either side of that bar character also. A simple <quote>gif</quote> on one side, and the other
8103 side will in turn match either <quote>jpeg</quote> or <quote>jpg</quote>,
8104 since the <quote>?</quote> means the letter <quote>e</quote> is optional and
8105 can be matched once or not at all. So we are building an expression here to
8106 match image GIF or JPEG type image file. It must include the literal
8107 string <quote>advert</quote>, then one or more digits, and a <quote>.</quote>
8108 (which is now a literal, and not a special character, since it is escaped
8109 with <quote>\</quote>), and lastly either <quote>gif</quote>, or
8110 <quote>jpeg</quote>, or <quote>jpg</quote>. Some possible matches would
8111 include: <quote>//advert1.jpg</quote>,
8112 <quote>/nasty/ads/advert1234.gif</quote>,
8113 <quote>/banners/from/hell/advert99.jpg</quote>. It would not match
8114 <quote>advert1.gif</quote> (no leading slash), or
8115 <quote>/adverts232.jpg</quote> (the expression does not include an
8116 <quote>s</quote>), or <quote>/advert1.jsp</quote> (<quote>jsp</quote> is not
8117 in the expression anywhere).
8121 We are barely scratching the surface of regular expressions here so that you
8122 can understand the default <application>Privoxy</application>
8123 configuration files, and maybe use this knowledge to customize your own
8124 installation. There is much, much more that can be done with regular
8125 expressions. Now that you know enough to get started, you can learn more on
8130 More reading on Perl Compatible Regular expressions:
8131 <ulink url="http://perldoc.perl.org/perlre.html">http://perldoc.perl.org/perlre.html</ulink>
8135 For information on regular expression based substitutions and their applications
8136 in filters, please see the <link linkend="filter-file">filter file tutorial</link>
8141 <!-- ~ End section ~ -->
8144 <!-- ~~~~~ New section ~~~~~ -->
8145 <sect2 id="internal-pages">
8146 <title>Privoxy's Internal Pages</title>
8149 Since <application>Privoxy</application> proxies each requested
8150 web page, it is easy for <application>Privoxy</application> to
8151 trap certain special URLs. In this way, we can talk directly to
8152 <application>Privoxy</application>, and see how it is
8153 configured, see how our rules are being applied, change these
8154 rules and other configuration options, and even turn
8155 <application>Privoxy's</application> filtering off, all with
8160 The URLs listed below are the special ones that allow direct access
8161 to <application>Privoxy</application>. Of course,
8162 <application>Privoxy</application> must be running to access these. If
8163 not, you will get a friendly error message. Internet access is not
8175 <ulink url="http://config.privoxy.org/">http://config.privoxy.org/</ulink>
8179 There is a shortcut: <ulink url="http://p.p/">http://p.p/</ulink> (But it
8180 doesn't provide a fall-back to a real page, in case the request is not
8181 sent through <application>Privoxy</application>)
8187 View and toggle client tags:
8191 <ulink url="http://config.privoxy.org/client-tags">http://config.privoxy.org/client-tags</ulink>
8198 Show information about the current configuration, including viewing and
8199 editing of actions files:
8203 <ulink url="http://config.privoxy.org/show-status">http://config.privoxy.org/show-status</ulink>
8210 Show the browser's request headers:
8214 <ulink url="http://config.privoxy.org/show-request">http://config.privoxy.org/show-request</ulink>
8221 Show which actions apply to a URL and why:
8225 <ulink url="http://config.privoxy.org/show-url-info">http://config.privoxy.org/show-url-info</ulink>
8232 Toggle Privoxy on or off. This feature can be turned off/on in the main
8233 <filename>config</filename> file. When toggled <quote>off</quote>, <quote>Privoxy</quote>
8234 continues to run, but only as a pass-through proxy, with no actions taking
8239 <ulink url="http://config.privoxy.org/toggle">http://config.privoxy.org/toggle</ulink>
8243 Short cuts. Turn off, then on:
8247 <ulink url="http://config.privoxy.org/toggle?set=disable">http://config.privoxy.org/toggle?set=disable</ulink>
8252 <ulink url="http://config.privoxy.org/toggle?set=enable">http://config.privoxy.org/toggle?set=enable</ulink>
8262 <!-- ~~~~~ New section ~~~~~ -->
8264 <title>Chain of Events</title>
8266 Let's take a quick look at how some of <application>Privoxy's</application>
8267 core features are triggered, and the ensuing sequence of events when a web
8268 page is requested by your browser:
8274 First, your web browser requests a web page. The browser knows to send
8275 the request to <application>Privoxy</application>, which will in turn,
8276 relay the request to the remote web server after passing the following
8282 <application>Privoxy</application> traps any request for its own internal CGI
8283 pages (e.g <ulink url="http://p.p/">http://p.p/</ulink>) and sends the CGI page back to the browser.
8288 Next, <application>Privoxy</application> checks to see if the URL
8290 linkend="BLOCK"><quote>+block</quote></link> patterns. If
8291 so, the URL is then blocked, and the remote web server will not be contacted.
8292 <link linkend="HANDLE-AS-IMAGE"><quote>+handle-as-image</quote></link>
8294 <link linkend="HANDLE-AS-EMPTY-DOCUMENT"><quote>+handle-as-empty-document</quote></link>
8295 are then checked, and if there is no match, an
8296 HTML <quote>BLOCKED</quote> page is sent back to the browser. Otherwise, if
8297 it does match, an image is returned for the former, and an empty text
8298 document for the latter. The type of image would depend on the setting of
8299 <link linkend="SET-IMAGE-BLOCKER"><quote>+set-image-blocker</quote></link>
8300 (blank, checkerboard pattern, or an HTTP redirect to an image elsewhere).
8305 Untrusted URLs are blocked. If URLs are being added to the
8306 <filename>trust</filename> file, then that is done.
8311 If the URL pattern matches the <link
8312 linkend="FAST-REDIRECTS"><quote>+fast-redirects</quote></link> action,
8313 it is then processed. Unwanted parts of the requested URL are stripped.
8318 Now the rest of the client browser's request headers are processed. If any
8319 of these match any of the relevant actions (e.g. <link
8320 linkend="HIDE-USER-AGENT"><quote>+hide-user-agent</quote></link>,
8321 etc.), headers are suppressed or forged as determined by these actions and
8327 Now the web server starts sending its response back (i.e. typically a web
8333 First, the server headers are read and processed to determine, among other
8334 things, the MIME type (document type) and encoding. The headers are then
8335 filtered as determined by the
8336 <link linkend="CRUNCH-INCOMING-COOKIES"><quote>+crunch-incoming-cookies</quote></link>,
8337 <link linkend="SESSION-COOKIES-ONLY"><quote>+session-cookies-only</quote></link>,
8338 and <link linkend="DOWNGRADE-HTTP-VERSION"><quote>+downgrade-http-version</quote></link>
8344 If any <link linkend="FILTER"><quote>+filter</quote></link> action
8346 linkend="DEANIMATE-GIFS"><quote>+deanimate-gifs</quote></link>
8347 action applies (and the document type fits the action), the rest of the page is
8348 read into memory (up to a configurable limit). Then the filter rules (from
8349 <filename>default.filter</filename> and any other filter files) are
8350 processed against the buffered content. Filters are applied in the order
8351 they are specified in one of the filter files. Animated GIFs, if present,
8352 are reduced to either the first or last frame, depending on the action
8353 setting.The entire page, which is now filtered, is then sent by
8354 <application>Privoxy</application> back to your browser.
8357 If neither a <link linkend="FILTER"><quote>+filter</quote></link> action
8359 linkend="DEANIMATE-GIFS"><quote>+deanimate-gifs</quote></link>
8360 matches, then <application>Privoxy</application> passes the raw data through
8361 to the client browser as it becomes available.
8366 As the browser receives the now (possibly filtered) page content, it
8367 reads and then requests any URLs that may be embedded within the page
8368 source, e.g. ad images, stylesheets, JavaScript, other HTML documents (e.g.
8369 frames), sounds, etc. For each of these objects, the browser issues a
8370 separate request (this is easily viewable in <application>Privoxy's</application>
8371 logs). And each such request is in turn processed just as above. Note that a
8372 complex web page will have many, many such embedded URLs. If these
8373 secondary requests are to a different server, then quite possibly a very
8374 differing set of actions is triggered.
8381 NOTE: This is somewhat of a simplistic overview of what happens with each URL
8382 request. For the sake of brevity and simplicity, we have focused on
8383 <application>Privoxy's</application> core features only.
8389 <!-- ~~~~~ New section ~~~~~ -->
8390 <sect2 id="actionsanat">
8391 <title>Troubleshooting: Anatomy of an Action</title>
8394 The way <application>Privoxy</application> applies
8395 <link linkend="ACTIONS">actions</link> and <link linkend="FILTER">filters</link>
8396 to any given URL can be complex, and not always so
8397 easy to understand what is happening. And sometimes we need to be able to
8398 <emphasis>see</emphasis> just what <application>Privoxy</application> is
8399 doing. Especially, if something <application>Privoxy</application> is doing
8400 is causing us a problem inadvertently. It can be a little daunting to look at
8401 the actions and filters files themselves, since they tend to be filled with
8402 <link linkend="regex">regular expressions</link> whose consequences are not
8407 One quick test to see if <application>Privoxy</application> is causing a problem
8408 or not, is to disable it temporarily. This should be the first troubleshooting
8409 step (be sure to flush caches afterward!). Looking at the
8410 logs is a good idea too. (Note that both the toggle feature and logging are
8411 enabled via <filename>config</filename> file settings, and may need to be
8412 turned <quote>on</quote>.)
8415 Another easy troubleshooting step to try is if you have done any
8416 customization of your installation, revert back to the installed
8417 defaults and see if that helps. There are times the developers get complaints
8418 about one thing or another, and the problem is more related to a customized
8419 configuration issue.
8423 <application>Privoxy</application> also provides the
8424 <ulink url="http://config.privoxy.org/show-url-info">http://config.privoxy.org/show-url-info</ulink>
8425 page that can show us very specifically how <application>actions</application>
8426 are being applied to any given URL. This is a big help for troubleshooting.
8430 First, enter one URL (or partial URL) at the prompt, and then
8431 <application>Privoxy</application> will tell us
8432 how the current configuration will handle it. This will not
8433 help with filtering effects (i.e. the <link
8434 linkend="FILTER"><quote>+filter</quote></link> action) from
8435 one of the filter files since this is handled very
8436 differently and not so easy to trap! It also will not tell you about any other
8437 URLs that may be embedded within the URL you are testing. For instance, images
8438 such as ads are expressed as URLs within the raw page source of HTML pages. So
8439 you will only get info for the actual URL that is pasted into the prompt area
8440 -- not any sub-URLs. If you want to know about embedded URLs like ads, you
8441 will have to dig those out of the HTML source. Use your browser's <quote>View
8442 Page Source</quote> option for this. Or right click on the ad, and grab the
8447 Let's try an example, <ulink url="http://google.com">google.com</ulink>,
8448 and look at it one section at a time in a sample configuration (your real
8449 configuration may vary):
8453 Matches for http://www.google.com:
8455 In file: default.action <guibutton>[ View ]</guibutton> <guibutton>[ Edit ]</guibutton>
8457 {+change-x-forwarded-for{block}
8458 +deanimate-gifs {last}
8459 +fast-redirects {check-decoded-url}
8460 +filter {refresh-tags}
8461 +filter {img-reorder}
8462 +filter {banners-by-size}
8464 +filter {jumping-windows}
8465 +filter {ie-exploits}
8466 +hide-from-header {block}
8467 +hide-referrer {forge}
8468 +session-cookies-only
8469 +set-image-blocker {pattern}
8472 { -session-cookies-only }
8478 In file: user.action <guibutton>[ View ]</guibutton> <guibutton>[ Edit ]</guibutton>
8479 (no matches in this file)
8483 This is telling us how we have defined our
8484 <link linkend="ACTIONS"><quote>actions</quote></link>, and
8485 which ones match for our test case, <quote>google.com</quote>.
8486 Displayed is all the actions that are available to us. Remember,
8487 the <literal>+</literal> sign denotes <quote>on</quote>. <literal>-</literal>
8488 denotes <quote>off</quote>. So some are <quote>on</quote> here, but many
8489 are <quote>off</quote>. Each example we try may provide a slightly different
8490 end result, depending on our configuration directives.
8494 is for our <filename>default.action</filename> file. The large, multi-line
8495 listing, is how the actions are set to match for all URLs, i.e. our default
8496 settings. If you look at your <quote>actions</quote> file, this would be the
8497 section just below the <quote>aliases</quote> section near the top. This
8498 will apply to all URLs as signified by the single forward slash at the end
8499 of the listing -- <quote> / </quote>.
8503 But we have defined additional actions that would be exceptions to these general
8504 rules, and then we list specific URLs (or patterns) that these exceptions
8505 would apply to. Last match wins. Just below this then are two explicit
8506 matches for <quote>.google.com</quote>. The first is negating our previous
8507 cookie setting, which was for <link
8508 linkend="SESSION-COOKIES-ONLY"><quote>+session-cookies-only</quote></link>
8509 (i.e. not persistent). So we will allow persistent cookies for google, at
8510 least that is how it is in this example. The second turns
8511 <emphasis>off</emphasis> any <link
8512 linkend="FAST-REDIRECTS"><quote>+fast-redirects</quote></link>
8513 action, allowing this to take place unmolested. Note that there is a leading
8514 dot here -- <quote>.google.com</quote>. This will match any hosts and
8515 sub-domains, in the google.com domain also, such as
8516 <quote>www.google.com</quote> or <quote>mail.google.com</quote>. But it would not
8517 match <quote>www.google.de</quote>! So, apparently, we have these two actions
8518 defined as exceptions to the general rules at the top somewhere in the lower
8519 part of our <filename>default.action</filename> file, and
8520 <quote>google.com</quote> is referenced somewhere in these latter sections.
8524 Then, for our <filename>user.action</filename> file, we again have no hits.
8525 So there is nothing google-specific that we might have added to our own, local
8526 configuration. If there was, those actions would over-rule any actions from
8527 previously processed files, such as <filename>default.action</filename>.
8528 <filename>user.action</filename> typically has the last word. This is the
8529 best place to put hard and fast exceptions,
8533 And finally we pull it all together in the bottom section and summarize how
8534 <application>Privoxy</application> is applying all its <quote>actions</quote>
8535 to <quote>google.com</quote>:
8543 +change-x-forwarded-for{block}
8544 -client-header-filter{hide-tor-exit-notation}
8545 -content-type-overwrite
8546 -crunch-client-header
8547 -crunch-if-none-match
8548 -crunch-incoming-cookies
8549 -crunch-outgoing-cookies
8550 -crunch-server-header
8551 +deanimate-gifs {last}
8552 -downgrade-http-version
8555 -filter {content-cookies}
8556 -filter {all-popups}
8557 -filter {banners-by-link}
8558 -filter {tiny-textforms}
8559 -filter {frameset-borders}
8560 -filter {demoronizer}
8561 -filter {shockwave-flash}
8562 -filter {quicktime-kioskmode}
8564 -filter {crude-parental}
8565 -filter {site-specifics}
8566 -filter {js-annoyances}
8567 -filter {html-annoyances}
8568 +filter {refresh-tags}
8569 -filter {unsolicited-popups}
8570 +filter {img-reorder}
8571 +filter {banners-by-size}
8573 +filter {jumping-windows}
8574 +filter {ie-exploits}
8581 -handle-as-empty-document
8583 -hide-accept-language
8584 -hide-content-disposition
8585 +hide-from-header {block}
8586 -hide-if-modified-since
8587 +hide-referrer {forge}
8590 -overwrite-last-modified
8591 -prevent-compression
8593 -server-header-filter{xml-to-html}
8594 -server-header-filter{html-to-xml}
8595 -session-cookies-only
8596 +set-image-blocker {pattern}
8600 Notice the only difference here to the previous listing, is to
8601 <quote>fast-redirects</quote> and <quote>session-cookies-only</quote>,
8602 which are activated specifically for this site in our configuration,
8603 and thus show in the <quote>Final Results</quote>.
8607 Now another example, <quote>ad.doubleclick.net</quote>:
8611 { +block{Domains starts with "ad"} }
8614 { +block{Domain contains "ad"} }
8617 { +block{Doubleclick banner server} +handle-as-image }
8618 .[a-vx-z]*.doubleclick.net
8622 We'll just show the interesting part here - the explicit matches. It is
8623 matched three different times. Two <quote>+block{}</quote> sections,
8624 and a <quote>+block{} +handle-as-image</quote>,
8625 which is the expanded form of one of our aliases that had been defined as:
8626 <quote>+block-as-image</quote>. (<link
8627 linkend="ALIASES"><quote>Aliases</quote></link> are defined in
8628 the first section of the actions file and typically used to combine more
8633 Any one of these would have done the trick and blocked this as an unwanted
8634 image. This is unnecessarily redundant since the last case effectively
8635 would also cover the first. No point in taking chances with these guys
8636 though ;-) Note that if you want an ad or obnoxious
8637 URL to be invisible, it should be defined as <quote>ad.doubleclick.net</quote>
8638 is done here -- as both a <link
8639 linkend="BLOCK"><quote>+block{}</quote></link>
8640 <emphasis>and</emphasis> an
8641 <link linkend="HANDLE-AS-IMAGE"><quote>+handle-as-image</quote></link>.
8642 The custom alias <quote><literal>+block-as-image</literal></quote> just
8643 simplifies the process and make it more readable.
8647 One last example. Let's try <quote>http://www.example.net/adsl/HOWTO/</quote>.
8648 This one is giving us problems. We are getting a blank page. Hmmm ...
8652 Matches for http://www.example.net/adsl/HOWTO/:
8654 In file: default.action <guibutton>[ View ]</guibutton> <guibutton>[ Edit ]</guibutton>
8658 +change-x-forwarded-for{block}
8659 -client-header-filter{hide-tor-exit-notation}
8660 -content-type-overwrite
8661 -crunch-client-header
8662 -crunch-if-none-match
8663 -crunch-incoming-cookies
8664 -crunch-outgoing-cookies
8665 -crunch-server-header
8667 -downgrade-http-version
8668 +fast-redirects {check-decoded-url}
8670 -filter {content-cookies}
8671 -filter {all-popups}
8672 -filter {banners-by-link}
8673 -filter {tiny-textforms}
8674 -filter {frameset-borders}
8675 -filter {demoronizer}
8676 -filter {shockwave-flash}
8677 -filter {quicktime-kioskmode}
8679 -filter {crude-parental}
8680 -filter {site-specifics}
8681 -filter {js-annoyances}
8682 -filter {html-annoyances}
8683 +filter {refresh-tags}
8684 -filter {unsolicited-popups}
8685 +filter {img-reorder}
8686 +filter {banners-by-size}
8688 +filter {jumping-windows}
8689 +filter {ie-exploits}
8696 -handle-as-empty-document
8698 -hide-accept-language
8699 -hide-content-disposition
8700 +hide-from-header{block}
8701 +hide-referer{forge}
8703 -overwrite-last-modified
8704 +prevent-compression
8706 -server-header-filter{xml-to-html}
8707 -server-header-filter{html-to-xml}
8708 +session-cookies-only
8709 +set-image-blocker{blank} }
8712 { +block{Path contains "ads".} +handle-as-image }
8717 Ooops, the <quote>/adsl/</quote> is matching <quote>/ads</quote> in our
8718 configuration! But we did not want this at all! Now we see why we get the
8719 blank page. It is actually triggering two different actions here, and
8720 the effects are aggregated so that the URL is blocked, and &my-app; is told
8721 to treat the block as if it were an image. But this is, of course, all wrong.
8722 We could now add a new action below this (or better in our own
8723 <filename>user.action</filename> file) that explicitly
8724 <emphasis>un</emphasis> blocks (
8725 <link linkend="BLOCK"><quote>{-block}</quote></link>) paths with
8726 <quote>adsl</quote> in them (remember, last match in the configuration
8727 wins). There are various ways to handle such exceptions. Example:
8736 Now the page displays ;-)
8737 Remember to flush your browser's caches when making these kinds of changes to
8738 your configuration to insure that you get a freshly delivered page! Or, try
8739 using <literal>Shift+Reload</literal>.
8743 But now what about a situation where we get no explicit matches like
8748 { +block{Path starts with "ads".} +handle-as-image }
8753 That actually was very helpful and pointed us quickly to where the problem
8754 was. If you don't get this kind of match, then it means one of the default
8755 rules in the first section of <filename>default.action</filename> is causing
8756 the problem. This would require some guesswork, and maybe a little trial and
8757 error to isolate the offending rule. One likely cause would be one of the
8758 <link linkend="FILTER"><quote>+filter</quote></link> actions.
8759 These tend to be harder to troubleshoot.
8760 Try adding the URL for the site to one of aliases that turn off
8761 <link linkend="FILTER"><quote>+filter</quote></link>:
8767 .worldpay.com # for quietpc.com
8774 <quote><literal>{ shop }</literal></quote> is an <quote>alias</quote> that expands to
8775 <quote><literal>{ -filter -session-cookies-only }</literal></quote>.
8776 Or you could do your own exception to negate filtering:
8781 # Disable ALL filter actions for sites in this section
8788 This would turn off all filtering for these sites. This is best
8789 put in <filename>user.action</filename>, for local site
8790 exceptions. Note that when a simple domain pattern is used by itself (without
8791 the subsequent path portion), all sub-pages within that domain are included
8792 automatically in the scope of the action.
8796 Images that are inexplicably being blocked, may well be hitting the
8797 <link linkend="FILTER-BANNERS-BY-SIZE"><quote>+filter{banners-by-size}</quote></link>
8799 that images of certain sizes are ad banners (works well
8800 <emphasis>most of the time</emphasis> since these tend to be standardized).
8804 <quote><literal>{ fragile }</literal></quote> is an alias that disables most
8805 actions that are the most likely to cause trouble. This can be used as a
8806 last resort for problem sites.
8811 # Handle with care: easy to break
8813 mybank.example.com</screen>
8817 <emphasis>Remember to flush caches!</emphasis> Note that the
8818 <literal>mail.google</literal> reference lacks the TLD portion (e.g.
8819 <quote>.com</quote>). This will effectively match any TLD with
8820 <literal>google</literal> in it, such as <literal>mail.google.de.</literal>,
8824 If this still does not work, you will have to go through the remaining
8825 actions one by one to find which one(s) is causing the problem.
8834 This program is free software; you can redistribute it
8835 and/or modify it under the terms of the GNU General
8836 Public License as published by the Free Software
8837 Foundation; either version 2 of the License, or (at
8838 your option) any later version.
8840 This program is distributed in the hope that it will
8841 be useful, but WITHOUT ANY WARRANTY; without even the
8842 implied warranty of MERCHANTABILITY or FITNESS FOR A
8843 PARTICULAR PURPOSE. See the GNU General Public
8844 License for more details.
8846 The GNU General Public License should be included with
8847 this file. If not, you can view it at
8848 http://www.gnu.org/copyleft/gpl.html
8849 or write to the Free Software Foundation, Inc.,
8850 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,