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5 <!entity p-intro SYSTEM "privoxy.sgml">
6 <!entity seealso SYSTEM "seealso.sgml">
7 <!entity buildsource SYSTEM "buildsource.sgml">
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10 <!entity copyright SYSTEM "copyright.sgml">
11 <!entity license SYSTEM "license.sgml">
12 <!entity GPLv2 SYSTEM "../../LICENSE">
13 <!entity p-authors SYSTEM "p-authors.sgml">
14 <!entity config SYSTEM "p-config.sgml">
15 <!entity changelog SYSTEM "changelog.sgml">
16 <!entity p-version "3.0.27">
17 <!entity p-status "UNRELEASED">
18 <!entity % p-authors-formal "INCLUDE"> <!-- include additional text, etc -->
19 <!entity % p-not-stable "INCLUDE">
20 <!entity % p-stable "IGNORE">
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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24 <!entity % user-man "IGNORE">
25 <!entity % config-file "IGNORE">
26 <!entity % p-supp-userman "IGNORE"> <!-- Omit some from supported.sgml -->
27 <!entity my-copy "©"> <!-- kludge for docbook2man -->
28 <!entity % draft "IGNORE"> <!-- WIP stuff -->
29 <!entity % seealso-extra "INCLUDE"> <!-- extra stuff from seealso.sgml -->
30 <!entity my-app "<application>Privoxy</application>">
33 File : doc/source/user-manual.sgml
37 Copyright (C) 2001-2018 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; 2001-2018 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 CVS sources). And there <emphasis>may be</emphasis> bugs, though hopefully
129 <!-- ~~~~~ New section ~~~~~ -->
130 <sect2 id="features"><title>Features</title>
132 In addition to the core
133 features of ad blocking and
134 <ulink url="http://en.wikipedia.org/wiki/Browser_cookie">cookie</ulink> management,
135 <application>Privoxy</application> provides many supplemental
136 features<![%p-not-stable;[, some of them currently under development]]>,
137 that give the end-user more control, more privacy and more freedom:
139 <!-- Include newfeatures.sgml boilerplate here: -->
141 <!-- end boilerplate -->
146 <!-- ~ End section ~ -->
149 <!-- ~~~~~ New section ~~~~~ -->
150 <sect1 id="installation"><title>Installation</title>
153 <application>Privoxy</application> is available both in convenient pre-compiled
154 packages for a wide range of operating systems, and as raw source code.
155 For most users, we recommend using the packages, which can be downloaded from our
156 <ulink url="https://sourceforge.net/projects/ijbswa/">Privoxy Project
162 On some platforms, the installer may remove previously installed versions, if
163 found. (See below for your platform). In any case <emphasis>be sure to backup
164 your old configuration if it is valuable to you.</emphasis> See the <link
165 linkend="upgradersnote">note to upgraders</link> section below.
168 <!-- ~~~~~ New section ~~~~~ -->
169 <sect2 id="installation-packages"><title>Binary Packages</title>
171 How to install the binary packages depends on your operating system:
174 <!-- XXX: The installation sections should be sorted -->
176 <!-- ~~~~~ New section ~~~~~ -->
177 <sect3 id="installation-deb"><title>Debian and Ubuntu</title>
179 DEBs can be installed with <literal>apt-get install privoxy</literal>,
180 and will use <filename>/etc/privoxy</filename> for the location of
185 <!-- ~~~~~ New section ~~~~~ -->
186 <sect3 id="installation-pack-win"><title>Windows</title>
189 Just double-click the installer, which will guide you through
190 the installation process. You will find the configuration files
191 in the same directory as you installed <application>Privoxy</application> in.
194 Version 3.0.5 beta introduced full <application>Windows</application> service
195 functionality. On Windows only, the <application>Privoxy</application>
196 program has two new command line arguments to install and uninstall
197 <application>Privoxy</application> as a <emphasis>service</emphasis>.
201 <term>Arguments:</term>
204 <replaceable class="parameter">--install</replaceable>[:<replaceable class="parameter">service_name</replaceable>]
207 <replaceable class="parameter">--uninstall</replaceable>[:<replaceable class="parameter">service_name</replaceable>]
213 After invoking <application>Privoxy</application> with
214 <command>--install</command>, you will need to bring up the
215 <application>Windows</application> service console to assign the user you
216 want <application>Privoxy</application> to run under, and whether or not you
217 want it to run whenever the system starts. You can start the
218 <application>Windows</application> services console with the following
219 command: <command>services.msc</command>. If you do not take the manual step
220 of modifying <application>Privoxy's</application> service settings, it will
221 not start. Note too that you will need to give Privoxy a user account that
222 actually exists, or it will not be permitted to
223 write to its log and configuration files.
228 <!-- ~~~~~ New section ~~~~~ -->
229 <sect3 id="installation-os2"><title>OS/2</title>
232 First, make sure that no previous installations of
233 <application>Junkbuster</application> and / or
234 <application>Privoxy</application> are left on your
235 system. Check that no <application>Junkbuster</application>
236 or <application>Privoxy</application> objects are in
241 Then, just double-click the WarpIN self-installing archive, which will
242 guide you through the installation process. A shadow of the
243 <application>Privoxy</application> executable will be placed in your
244 startup folder so it will start automatically whenever OS/2 starts.
248 The directory you choose to install <application>Privoxy</application>
249 into will contain all of the configuration files.
253 <!-- ~~~~~ New section ~~~~~ -->
254 <sect3 id="installation-mac"><title>Mac OS X</title>
256 Installation instructions for the OS X platform depend upon whether
257 you downloaded a ready-built installation package (.pkg or .mpkg) or have
258 downloaded the source code.
261 <sect3 renderas="sect4" id="OS-X-install-from-package">
262 <title>Installation from ready-built package</title>
264 The downloaded file will either be a .pkg (for OS X 10.5 upwards) or a bzipped
265 .mpkg file (for OS X 10.4). The former can be double-clicked as is and the
266 installation will start; double-clicking the latter will unzip the .mpkg file
267 which can then be double-clicked to commence the installation.
270 The privoxy service will automatically start after a successful installation
271 (and thereafter every time your computer starts up) however you will need to
272 configure your web browser(s) to use it. To do so, configure them to use a
273 proxy for HTTP and HTTPS at the address 127.0.0.1:8118.
276 To prevent the privoxy service from automatically starting when your computer
277 starts up, remove or rename the file <literal>/Library/LaunchDaemons/org.ijbswa.privoxy.plist</literal>
278 (on OS X 10.5 and higher) or the folder named
279 <literal>/Library/StartupItems/Privoxy</literal> (on OS X 10.4 'Tiger').
282 To manually start or stop the privoxy service, use the scripts startPrivoxy.sh
283 and stopPrivoxy.sh supplied in /Applications/Privoxy. They must be run from an
284 administrator account, using sudo.
287 To uninstall, run /Applications/Privoxy/uninstall.command as sudo from an
288 administrator account.
291 <sect3 renderas="sect4" id="OS-X-install-from-source">
292 <title>Installation from source</title>
294 To build and install the Privoxy source code on OS X you will need to obtain
295 the macsetup module from the Privoxy Sourceforge CVS repository (refer to
296 Sourceforge help for details of how to set up a CVS client to have read-only
297 access to the repository). This module contains scripts that leverage the usual
298 open-source tools (available as part of Apple's free of charge Xcode
299 distribution or via the usual open-source software package managers for OS X
300 (MacPorts, Homebrew, Fink etc.) to build and then install the privoxy binary
301 and associated files. The macsetup module's README file contains complete
302 instructions for its use.
305 The privoxy service will automatically start after a successful installation
306 (and thereafter every time your computer starts up) however you will need to
307 configure your web browser(s) to use it. To do so, configure them to use a
308 proxy for HTTP and HTTPS at the address 127.0.0.1:8118.
311 To prevent the privoxy service from automatically starting when your computer
312 starts up, remove or rename the file <literal>/Library/LaunchDaemons/org.ijbswa.privoxy.plist</literal>
313 (on OS X 10.5 and higher) or the folder named
314 <literal>/Library/StartupItems/Privoxy</literal> (on OS X 10.4 'Tiger').
317 To manually start or stop the privoxy service, use the Privoxy Utility
318 for Mac OS X (also part of the macsetup module). This application can start
319 and stop the privoxy service and display its log and configuration files.
322 To uninstall, run the macsetup module's uninstall.sh as sudo from an
323 administrator account.
327 <!-- ~~~~~ New section ~~~~~ -->
328 <sect3 id="installation-freebsd"><title>FreeBSD</title>
331 Privoxy is part of FreeBSD's Ports Collection, you can build and install
332 it with <literal>cd /usr/ports/www/privoxy; make install clean</literal>.
338 <!-- ~~~~~ New section ~~~~~ -->
339 <sect2 id="installation-source"><title>Building from Source</title>
342 The most convenient way to obtain the <application>Privoxy</application> source
343 code is to download the source tarball from our
344 <ulink url="https://sourceforge.net/projects/ijbswa/files/Sources/">
345 project download page</ulink>,
346 or you can get the up-to-the-minute, possibly unstable, development version from
347 <ulink url="https://www.privoxy.org/">https://www.privoxy.org/</ulink>.
350 <!-- include buildsource.sgml boilerplate: -->
352 <!-- end boilerplate -->
355 <sect3 id="WINBUILD-CYGWIN"><title>Windows</title>
357 <sect4 id="WINBUILD-SETUP"><title>Setup</title>
359 Install the Cygwin utilities needed to build <application>Privoxy</application>.
360 If you have a 64 bit CPU (which most people do by now), get the
361 Cygwin setup-x86_64.exe program <ulink url="https://cygwin.com/setup-x86_64.exe">here</ulink>
362 (the .sig file is <ulink url="https://cygwin.com/setup-x86_64.exe.sig">here</ulink>).
365 Run the setup program and from View / Category select:
377 mingw64-i686-gcc-core
382 libxslt: GNOME XSLT library (runtime)
398 If you haven't already downloaded the Privoxy source code, get it now:
403 git clone https://www.privoxy.org/git/privoxy.git
407 Get the source code (.zip or .tar.gz) for tidy from
408 <ulink url="https://github.com/htacg/tidy-html5/releases">
409 https://github.com/htacg/tidy-html5/releases</ulink>,
410 unzip into <root-dir> and build the software:
414 cd tidy-html5-x.y.z/build/cmake
415 cmake ../.. -DCMAKE_BUILD_TYPE=Release -DBUILD_SHARED_LIB:BOOL=OFF -DCMAKE_INSTALL_PREFIX=/usr/local
420 If you want to be able to make a Windows release package, get the NSIS .zip file from
421 <!-- FIXME: which version(s) are known to work? -->
422 <ulink url="https://sourceforge.net/projects/nsis/files/NSIS%203/">
423 https://sourceforge.net/projects/nsis/files/NSIS%203/</ulink>
424 and extract the NSIS directory to <literal>privoxy/windows</literal>.
425 Then edit the windows/GNUmakefile to set the location of the NSIS executable - eg:
429 MAKENSIS = ./nsis/makensis.exe
434 <sect4 id="WINBUILD-BUILD"><title>Build</title>
437 To build just the Privoxy executable and not the whole installation package, do:
440 cd <root-dir>/privoxy
441 ./windows/MYconfigure && make
445 Privoxy uses the <ulink url="https://en.wikipedia.org/wiki/GNU_build_system">GNU Autotools</ulink>
446 for building software, so the process is:
449 $ autoheader # creates config.h.in
450 $ autoconf # uses config.h.in to create the configure shell script
451 $ ./configure [options] # creates GNUmakefile
452 $ make [options] # builds the program
456 The usual <literal>configure</literal> options for building a native Windows application under cygwin are
459 <literallayout class="Monospaced">
460 --host=i686-w64-mingw32
463 --enable-static-linking
465 --disable-dynamic-pcre
469 You can set the <literal>CFLAGS</literal> and <literal>LDFLAGS</literal> envars before
470 running <literal>configure</literal> to set compiler and linker flags. For example:
474 $ export CFLAGS="-O2" # set gcc optimization level
475 $ export LDFLAGS="-Wl,--nxcompat" # Enable DEP
476 $ ./configure --host=i686-w64-mingw32 --enable-mingw32 --enable-zlib \
477 > --enable-static-linking --disable-pthread --disable-dynamic-pcre
478 $ make # build Privoxy
482 See the <ulink url="../developer-manual/newrelease.html#NEWRELEASE-WINDOWS">Developer's Manual</ulink>
483 for building a Windows release package.
491 <!-- ~~~~~ New section ~~~~~ -->
492 <sect2 id="installation-keepupdated"><title>Keeping your Installation Up-to-Date</title>
495 If you wish to receive an email notification whenever we release updates of
496 <application>Privoxy</application> or the actions file, <ulink
497 url="https://lists.privoxy.org/mailman/listinfo/privoxy-announce">subscribe
498 to our announce mailing list</ulink>, privoxy-announce@lists.privoxy.org.
502 In order not to lose your personal changes and adjustments when updating
503 to the latest <literal>default.action</literal> file we <emphasis>strongly
504 recommend</emphasis> that you use <literal>user.action</literal> and
505 <literal>user.filter</literal> for your local
506 customizations of <application>Privoxy</application>. See the <link
507 linkend="actions-file">Chapter on actions files</link> for details.
515 <!-- ~ End section ~ -->
517 <!-- ~~~~~ New section ~~~~~ -->
518 <sect1 id="whatsnew">
519 <title>What's New in this Release</title>
523 <!-- ~~~~~ New section ~~~~~ -->
525 <sect2 id="upgradersnote">
526 <title>Note to Upgraders</title>
529 A quick list of things to be aware of before upgrading from earlier
530 versions of <application>Privoxy</application>:
537 The recommended way to upgrade &my-app; is to backup your old
538 configuration files, install the new ones, verify that &my-app;
539 is working correctly and finally merge back your changes using
540 <application>diff</application> and maybe <application>patch</application>.
543 There are a number of new features in each &my-app; release and
544 most of them have to be explicitly enabled in the configuration
545 files. Old configuration files obviously don't do that and due
546 to syntax changes using old configuration files with a new
547 &my-app; isn't always possible anyway.
552 Note that some installers remove earlier versions completely,
553 including configuration files, therefore you should really save
554 any important configuration files!
559 On the other hand, other installers don't overwrite existing configuration
560 files, thinking you will want to do that yourself.
565 In the default configuration only fatal errors are logged now.
566 You can change that in the <link linkend="DEBUG">debug section</link>
567 of the configuration file. You may also want to enable more verbose
568 logging until you verified that the new &my-app; version is working
575 Three other config file settings are now off by default:
576 <link linkend="enable-remote-toggle">enable-remote-toggle</link>,
577 <link linkend="enable-remote-http-toggle">enable-remote-http-toggle</link>,
578 and <link linkend="enable-edit-actions">enable-edit-actions</link>.
579 If you use or want these, you will need to explicitly enable them, and
580 be aware of the security issues involved.
587 What constitutes a <quote>default</quote> configuration has changed,
588 and you may want to review which actions are <quote>on</quote> by
589 default. This is primarily a matter of emphasis, but some features
590 you may have been used to, may now be <quote>off</quote> by default.
591 There are also a number of new actions and filters you may want to
592 consider, most of which are not fully incorporated into the default
593 settings as yet (see above).
600 The default actions setting is now <literal>Cautious</literal>. Previous
601 releases had a default setting of <literal>Medium</literal>. Experienced
602 users may want to adjust this, as it is fairly conservative by &my-app;
603 standards and past practices. See <ulink
604 url="http://config.privoxy.org/edit-actions-list?f=default">
605 http://config.privoxy.org/edit-actions-list?f=default</ulink>. New users
606 should try the default settings for a while before turning up the volume.
612 The default setting has filtering turned <emphasis>off</emphasis>, which
613 subsequently means that compression is <emphasis>on</emphasis>. Remember
614 that filtering does not work on compressed pages, so if you use, or want to
615 use, filtering, you will need to force compression off. Example:
618 { +<link linkend="filter">filter</link>{google} +<link linkend="prevent-compression">prevent-compression</link> }
621 Or if you use a number of filters, or filter many sites, you may just want
622 to turn off compression for all sites in
623 <filename>default.action</filename> (or
624 <filename>user.action</filename>).
631 Also, <link linkend="SESSION-COOKIES-ONLY">session-cookies-only</link> is
632 off by default now. If you've liked this feature in the past, you may want
633 to turn it back on in <filename>user.action</filename> now.
640 Some installers may not automatically start
641 <application>Privoxy</application> after installation.
651 <!-- ~~~~~ New section ~~~~~ -->
652 <sect1 id="quickstart"><title>Quickstart to Using Privoxy</title>
658 Install <application>Privoxy</application>. See the <link
659 linkend="installation">Installation Section</link> below for platform specific
666 Advanced users and those who want to offer <application>Privoxy</application>
667 service to more than just their local machine should check the <link
668 linkend="config">main config file</link>, especially the <link
669 linkend="access-control">security-relevant</link> options. These are
676 Start <application>Privoxy</application>, if the installation program has
677 not done this already (may vary according to platform). See the section
678 <link linkend="startup">Starting <application>Privoxy</application></link>.
684 Set your browser to use <application>Privoxy</application> as HTTP and
685 HTTPS (SSL) <ulink url="http://en.wikipedia.org/wiki/Proxy_server">proxy</ulink>
686 by setting the proxy configuration for address of
687 <literal>127.0.0.1</literal> and port <literal>8118</literal>.
688 <emphasis>DO NOT</emphasis> activate proxying for <literal>FTP</literal> or
689 any protocols besides HTTP and HTTPS (SSL) unless you intend to prevent your
690 browser from using these protocols.
696 Flush your browser's disk and memory caches, to remove any cached ad images.
697 If using <application>Privoxy</application> to manage
698 <ulink url="http://en.wikipedia.org/wiki/Browser_cookie">cookies</ulink>,
699 you should remove any currently stored cookies too.
705 A default installation should provide a reasonable starting point for
706 most. There will undoubtedly be occasions where you will want to adjust the
707 configuration, but that can be dealt with as the need arises. Little
708 to no initial configuration is required in most cases, you may want
710 <ulink url="config.html#ENABLE-EDIT-ACTIONS">web-based action editor</ulink> though.
711 Be sure to read the warnings first.
714 See the <link linkend="configuration">Configuration section</link> for more
715 configuration options, and how to customize your installation.
716 You might also want to look at the <link
717 linkend="quickstart-ad-blocking">next section</link> for a quick
718 introduction to how <application>Privoxy</application> blocks ads and
725 If you experience ads that slip through, innocent images that are
726 blocked, or otherwise feel the need to fine-tune
727 <application>Privoxy's</application> behavior, take a look at the <link
728 linkend="actions-file">actions files</link>. As a quick start, you might
729 find the <link linkend="act-examples">richly commented examples</link>
730 helpful. You can also view and edit the actions files through the <ulink
731 url="http://config.privoxy.org">web-based user interface</ulink>. The
732 Appendix <quote><link linkend="actionsanat">Troubleshooting: Anatomy of an
733 Action</link></quote> has hints on how to understand and debug actions that
734 <quote>misbehave</quote>.
740 Please see the section <link linkend="contact">Contacting the
741 Developers</link> on how to report bugs, problems with websites or to get
748 Now enjoy surfing with enhanced control, comfort and privacy!
755 <!-- ~~~~~ New section ~~~~~ -->
757 <sect2 id="quickstart-ad-blocking">
758 <title>Quickstart to Ad Blocking</title>
760 NOTE: This section is deliberately redundant for those that don't
761 want to read the whole thing (which is getting lengthy).
764 Ad blocking is but one of <application>Privoxy's</application>
765 array of features. Many of these features are for the technically minded advanced
766 user. But, ad and banner blocking is surely common ground for everybody.
769 This section will provide a quick summary of ad blocking so
770 you can get up to speed quickly without having to read the more extensive
771 information provided below, though this is highly recommended.
774 First a bit of a warning ... blocking ads is much like blocking SPAM: the
775 more aggressive you are about it, the more likely you are to block
776 things that were not intended. And the more likely that some things
777 may not work as intended. So there is a trade off here. If you want
778 extreme ad free browsing, be prepared to deal with more
779 <quote>problem</quote> sites, and to spend more time adjusting the
780 configuration to solve these unintended consequences. In short, there is
781 not an easy way to eliminate <emphasis>all</emphasis> ads. Either take
782 the easy way and settle for <emphasis>most</emphasis> ads blocked with the
783 default configuration, or jump in and tweak it for your personal surfing
784 habits and preferences.
787 Secondly, a brief explanation of <application>Privoxy's </application>
788 <quote>actions</quote>. <quote>Actions</quote> in this context, are
789 the directives we use to tell <application>Privoxy</application> to perform
790 some task relating to HTTP transactions (i.e. web browsing). We tell
791 <application>Privoxy</application> to take some <quote>action</quote>. Each
792 action has a unique name and function. While there are many potential
793 <application>actions</application> in <application>Privoxy's</application>
794 arsenal, only a few are used for ad blocking. <link
795 linkend="actions">Actions</link>, and <link linkend="actions-file">action
796 configuration files</link>, are explained in depth below.
799 Actions are specified in <application>Privoxy's</application> configuration,
800 followed by one or more URLs to which the action should apply. URLs
801 can actually be URL type <link linkend="af-patterns">patterns</link> that use
802 wildcards so they can apply potentially to a range of similar URLs. The
803 actions, together with the URL patterns are called a section.
806 When you connect to a website, the full URL will either match one or more
807 of the sections as defined in <application>Privoxy's</application> configuration,
808 or not. If so, then <application>Privoxy</application> will perform the
809 respective actions. If not, then nothing special happens. Furthermore, web
810 pages may contain embedded, secondary URLs that your web browser will
811 use to load additional components of the page, as it parses the
812 original page's HTML content. An ad image for instance, is just an URL
813 embedded in the page somewhere. The image itself may be on the same server,
814 or a server somewhere else on the Internet. Complex web pages will have many
815 such embedded URLs. &my-app; can deal with each URL individually, so, for
816 instance, the main page text is not touched, but images from such-and-such
821 The most important actions for basic ad blocking are: <literal><link
822 linkend="block">block</link></literal>, <literal><link
823 linkend="handle-as-image">handle-as-image</link></literal>,
825 linkend="handle-as-empty-document">handle-as-empty-document</link></literal>,and
826 <literal><link linkend="set-image-blocker">set-image-blocker</link></literal>:
833 <literal><link linkend="block">block</link></literal> - this is perhaps
834 the single most used action, and is particularly important for ad blocking.
835 This action stops any contact between your browser and any URL patterns
836 that match this action's configuration. It can be used for blocking ads,
837 but also anything that is determined to be unwanted. By itself, it simply
838 stops any communication with the remote server and sends
839 <application>Privoxy</application>'s own built-in BLOCKED page instead to
840 let you now what has happened (with some exceptions, see below).
846 <literal><link linkend="handle-as-image">handle-as-image</link></literal> -
847 tells <application>Privoxy</application> to treat this URL as an image.
848 <application>Privoxy</application>'s default configuration already does this
849 for all common image types (e.g. GIF), but there are many situations where this
850 is not so easy to determine. So we'll force it in these cases. This is particularly
851 important for ad blocking, since only if we know that it's an image of
852 some kind, can we replace it with an image of our choosing, instead of the
853 <application>Privoxy</application> BLOCKED page (which would only result in
854 a <quote>broken image</quote> icon). There are some limitations to this
855 though. For instance, you can't just brute-force an image substitution for
856 an entire HTML page in most situations.
862 <literal><link linkend="handle-as-empty-document">handle-as-empty-document</link></literal> -
863 sends an empty document instead of <application>Privoxy's</application>
864 normal BLOCKED HTML page. This is useful for file types that are neither
865 HTML nor images, such as blocking JavaScript files.
872 linkend="set-image-blocker">set-image-blocker</link></literal> - tells
873 <application>Privoxy</application> what to display in place of an ad image that
874 has hit a block rule. For this to come into play, the URL must match a
875 <literal><link linkend="block">block</link></literal> action somewhere in the
876 configuration, <emphasis>and</emphasis>, it must also match an
877 <literal><link linkend="handle-as-image">handle-as-image</link></literal> action.
880 The configuration options on what to display instead of the ad are:
884 <emphasis>pattern</emphasis> - a checkerboard pattern, so that an ad
885 replacement is obvious. This is the default.
890 <emphasis>blank</emphasis> - A very small empty GIF image is displayed.
891 This is the so-called <quote>invisible</quote> configuration option.
896 <emphasis>http://<URL></emphasis> - A redirect to any image anywhere
897 of the user's choosing (advanced usage).
905 Advanced users will eventually want to explore &my-app;
906 <literal><link linkend="filter">filters</link></literal> as well. Filters
907 are very different from <literal><link
908 linkend="block">blocks</link></literal>.
909 A <quote>block</quote> blocks a site, page, or unwanted contented. Filters
910 are a way of filtering or modifying what is actually on the page. An example
911 filter usage: a text replacement of <quote>no-no</quote> for
912 <quote>nasty-word</quote>. That is a very simple example. This process can be
913 used for ad blocking, but it is more in the realm of advanced usage and has
914 some pitfalls to be wary off.
918 The quickest way to adjust any of these settings is with your browser through
919 the special <application>Privoxy</application> editor at <ulink
920 url="http://config.privoxy.org/show-status">http://config.privoxy.org/show-status</ulink>
921 (shortcut: <ulink url="http://p.p/">http://p.p/show-status</ulink>). This
922 is an internal page, and does not require Internet access.
926 Note that as of <application>Privoxy</application> 3.0.7 beta the
927 action editor is disabled by default. Check the
928 <ulink url="config.html#ENABLE-EDIT-ACTIONS">enable-edit-actions
929 section in the configuration file</ulink> to learn why and in which
930 cases it's safe to enable again.
934 If you decided to enable the action editor, select the appropriate
935 <quote>actions</quote> file, and click
936 <quote><guibutton>Edit</guibutton></quote>. It is best to put personal or
937 local preferences in <filename>user.action</filename> since this is not
938 meant to be overwritten during upgrades, and will over-ride the settings in
939 other files. Here you can insert new <quote>actions</quote>, and URLs for ad
940 blocking or other purposes, and make other adjustments to the configuration.
941 <application>Privoxy</application> will detect these changes automatically.
945 A quick and simple step by step example:
952 Right click on the ad image to be blocked, then select
953 <quote><guimenuitem>Copy Link Location</guimenuitem></quote> from the
961 url="http://config.privoxy.org/show-status">http://config.privoxy.org/show-status</ulink>
966 Find <filename>user.action</filename> in the top section, and click
967 on <quote><guibutton>Edit</guibutton></quote>:
970 <!-- image of editor and actions files selections -->
971 <figure pgwide="0" float="0"><title>Actions Files in Use</title>
974 <imagedata fileref="files-in-use.jpg" format="jpg">
977 <phrase>[ Screenshot of Actions Files in Use ]</phrase>
985 You should have a section with only
986 <literal><link linkend="block">block</link></literal> listed under
987 <quote>Actions:</quote>.
988 If not, click a <quote><guibutton>Insert new section below</guibutton></quote>
989 button, and in the new section that just appeared, click the
990 <guibutton>Edit</guibutton> button right under the word <quote>Actions:</quote>.
991 This will bring up a list of all actions. Find
992 <literal><link linkend="block">block</link></literal> near the top, and click
993 in the <quote>Enabled</quote> column, then <quote><guibutton>Submit</guibutton></quote>
999 Now, in the <literal><link linkend="block">block</link></literal> actions section,
1000 click the <quote><guibutton>Add</guibutton></quote> button, and paste the URL the
1001 browser got from <quote><guimenuitem>Copy Link Location</guimenuitem></quote>.
1002 Remove the <literal>http://</literal> at the beginning of the URL. Then, click
1003 <quote><guibutton>Submit</guibutton></quote> (or
1004 <quote><guibutton>OK</guibutton></quote> if in a pop-up window).
1009 Now go back to the original page, and press <keycap>SHIFT-Reload</keycap>
1010 (or flush all browser caches). The image should be gone now.
1017 This is a very crude and simple example. There might be good reasons to use a
1018 wildcard pattern match to include potentially similar images from the same
1019 site. For a more extensive explanation of <quote>patterns</quote>, and
1020 the entire actions concept, see <link linkend="actions-file">the Actions
1025 For advanced users who want to hand edit their config files, you might want
1026 to now go to the <link linkend="act-examples">Actions Files Tutorial</link>.
1027 The ideas explained therein also apply to the web-based editor.
1030 There are also various
1031 <link linkend="filter">filters</link> that can be used for ad blocking
1032 (filters are a special subset of actions). These
1033 fall into the <quote>advanced</quote> usage category, and are explained in
1034 depth in later sections.
1041 <!-- ~ End section ~ -->
1044 <!-- ~~~~~ New section ~~~~~ -->
1045 <sect1 id="startup">
1046 <title>Starting Privoxy</title>
1048 Before launching <application>Privoxy</application> for the first time, you
1049 will want to configure your browser(s) to use
1050 <application>Privoxy</application> as a HTTP and HTTPS (SSL)
1051 <ulink url="http://en.wikipedia.org/wiki/Proxy_server">proxy</ulink>. The default is
1052 127.0.0.1 (or localhost) for the proxy address, and port 8118 (earlier versions
1053 used port 8000). This is the one configuration step <emphasis>that must be done
1057 Please note that <application>Privoxy</application> can only proxy HTTP and
1058 HTTPS traffic. It will not work with FTP or other protocols.
1061 <!-- image of Mozilla Proxy configuration -->
1062 <figure pgwide="0" float="0"><title>Proxy Configuration Showing
1063 Mozilla/Netscape HTTP and HTTPS (SSL) Settings</title>
1066 <imagedata fileref="proxy_setup.jpg" format="jpg">
1069 <phrase>[ Screenshot of Mozilla Proxy Configuration ]</phrase>
1076 With <application>Firefox</application>, this is typically set under:
1080 <guibutton>Tools</guibutton> -> <guibutton>Options</guibutton> -> <guibutton>Advanced</guibutton> -> <guibutton>Network</guibutton> -><guibutton>Connection</guibutton> -> <guibutton>Settings</guibutton>
1084 Or optionally on some platforms:
1088 <guibutton>Edit</guibutton> -> <guibutton>Preferences</guibutton> -> <guibutton>General</guibutton> -> <guibutton>Connection Settings</guibutton> -> <guibutton>Manual Proxy Configuration</guibutton>
1093 With <application>Netscape</application> (and
1094 <application>Mozilla</application>), this can be set under:
1099 <!-- Mix ascii and gui art, something for everybody -->
1100 <!-- spacing on this is tricky -->
1101 <guibutton>Edit</guibutton> -> <guibutton>Preferences</guibutton> -> <guibutton>Advanced</guibutton> -> <guibutton>Proxies</guibutton> -> <guibutton>HTTP Proxy</guibutton>
1105 For <application>Internet Explorer v.5-7</application>:
1109 <guibutton>Tools</guibutton> -> <guibutton>Internet Options</guibutton> -> <guibutton>Connections</guibutton> -> <guibutton>LAN Settings</guibutton>
1113 Then, check <quote>Use Proxy</quote> and fill in the appropriate info
1114 (Address: 127.0.0.1, Port: 8118). Include HTTPS (SSL), if you want HTTPS
1115 proxy support too (sometimes labeled <quote>Secure</quote>). Make sure any
1116 checkboxes like <quote>Use the same proxy server for all protocols</quote> is
1117 <emphasis>UNCHECKED</emphasis>. You want only HTTP and HTTPS (SSL)!
1120 <!-- image of IE Proxy configuration -->
1121 <figure pgwide="0" float="0"><title>Proxy Configuration Showing
1122 Internet Explorer HTTP and HTTPS (Secure) Settings</title>
1125 <imagedata fileref="proxy2.jpg" format="jpg">
1128 <phrase>[ Screenshot of IE Proxy Configuration ]</phrase>
1135 After doing this, flush your browser's disk and memory caches to force a
1136 re-reading of all pages and to get rid of any ads that may be cached. Remove
1137 any <ulink url="http://en.wikipedia.org/wiki/Browser_cookie">cookies</ulink>,
1138 if you want <application>Privoxy</application> to manage that. You are now
1139 ready to start enjoying the benefits of using
1140 <application>Privoxy</application>!
1144 <application>Privoxy</application> itself is typically started by specifying the
1145 main configuration file to be used on the command line. If no configuration
1146 file is specified on the command line, <application>Privoxy</application>
1147 will look for a file named <filename>config</filename> in the current
1148 directory. Except on Win32 where it will try <filename>config.txt</filename>.
1151 <sect2 id="start-debian">
1152 <title>Debian</title>
1154 We use a script. Note that Debian typically starts &my-app; upon booting per
1155 default. It will use the file
1156 <filename>/etc/privoxy/config</filename> as its main configuration
1160 # /etc/init.d/privoxy start
1164 <sect2 id="start-freebsd">
1165 <title>FreeBSD and ElectroBSD</title>
1167 To start <application>Privoxy</application> upon booting, add
1168 "privoxy_enable='YES'" to <filename>/etc/rc.conf</filename>.
1169 <application>Privoxy</application> will use
1170 <filename>/usr/local/etc/privoxy/config</filename> as its main
1174 If you installed <application>Privoxy</application> into a jail, the
1175 paths above are relative to the jail root.
1178 To start <application>Privoxy</application> manually, run:
1181 # service privoxy onestart
1185 <sect2 id="start-windows">
1186 <title>Windows</title>
1188 Click on the &my-app; Icon to start <application>Privoxy</application>. If no configuration file is
1189 specified on the command line, <application>Privoxy</application> will look
1190 for a file named <filename>config.txt</filename>. Note that Windows will
1191 automatically start &my-app; when the system starts if you chose that option
1195 <application>Privoxy</application> can run with full Windows service functionality.
1196 On Windows only, the &my-app; program has two new command line arguments
1197 to install and uninstall &my-app; as a service. See the
1198 <link linkend="installation-pack-win">Windows Installation
1199 instructions</link> for details.
1203 <sect2 id="start-unices">
1204 <title>Generic instructions for Unix derivates (Solaris, NetBSD, HP-UX etc.)</title>
1206 Example Unix startup command:
1209 # /usr/sbin/privoxy --user privoxy /etc/privoxy/config
1212 Note that if you installed <application>Privoxy</application> through
1213 a package manager, the package will probably contain a platform-specific
1214 script or configuration file to start <application>Privoxy</application>
1219 <sect2 id="start-os2">
1222 During installation, <application>Privoxy</application> is configured to
1223 start automatically when the system restarts. You can start it manually by
1224 double-clicking on the <application>Privoxy</application> icon in the
1225 <application>Privoxy</application> folder.
1229 <sect2 id="start-macosx">
1230 <title>Mac OS X</title>
1232 The privoxy service will automatically start after a successful installation
1233 (and thereafter every time your computer starts up) however you will need to
1234 configure your web browser(s) to use it. To do so, configure them to use a
1235 proxy for HTTP and HTTPS at the address 127.0.0.1:8118.
1238 To prevent the privoxy service from automatically starting when your computer
1239 starts up, remove or rename the file <literal>/Library/LaunchDaemons/org.ijbswa.privoxy.plist</literal>
1240 (on OS X 10.5 and higher) or the folder named
1241 <literal>/Library/StartupItems/Privoxy</literal> (on OS X 10.4 'Tiger').
1244 To manually start or stop the privoxy service, use the scripts startPrivoxy.sh
1245 and stopPrivoxy.sh supplied in /Applications/Privoxy. They must be run from an
1246 administrator account, using sudo.
1254 See the section <link linkend="cmdoptions">Command line options</link> for
1258 must find a better place for this paragraph
1261 The included default configuration files should give a reasonable starting
1262 point. Most of the per site configuration is done in the
1263 <ulink url="actions-file.html"><quote>actions</quote></ulink> files. These are
1264 where various cookie actions are defined, ad and banner blocking, and other
1265 aspects of <application>Privoxy</application> configuration. There are several
1266 such files included, with varying levels of aggressiveness.
1270 You will probably want to keep an eye out for sites for which you may prefer
1271 persistent cookies, and add these to your actions configuration as needed. By
1272 default, most of these will be accepted only during the current browser
1273 session (aka <quote>session cookies</quote>), unless you add them to the
1274 configuration. If you want the browser to handle this instead, you will need
1275 to edit <filename>user.action</filename> (or through the web based interface)
1276 and disable this feature. If you use more than one browser, it would make
1277 more sense to let <application>Privoxy</application> handle this. In which
1278 case, the browser(s) should be set to accept all cookies.
1282 Another feature where you will probably want to define exceptions for trusted
1283 sites is the popup-killing (through <ulink
1284 url="actions-file.html#FILTER-POPUPS"><quote>+filter{popups}</quote></ulink>),
1285 because your favorite shopping, banking, or leisure site may need
1286 popups (explained below).
1290 <application>Privoxy</application> does not support all of the optional HTTP/1.1
1291 features yet. In the unlikely event that you experience inexplicable problems
1292 with browsers that use HTTP/1.1 per default
1293 (like <application>Mozilla</application> or recent versions of I.E.), you might
1294 try to force HTTP/1.0 compatibility. For Mozilla, look under <literal>Edit ->
1295 Preferences -> Debug -> Networking</literal>.
1296 Alternatively, set the <quote>+downgrade-http-version</quote> config option in
1297 <filename>default.action</filename> which will downgrade your browser's HTTP
1298 requests from HTTP/1.1 to HTTP/1.0 before processing them.
1302 After running <application>Privoxy</application> for a while, you can
1303 start to fine tune the configuration to suit your personal, or site,
1304 preferences and requirements. There are many, many aspects that can
1305 be customized. <quote>Actions</quote>
1306 can be adjusted by pointing your browser to
1307 <ulink url="http://config.privoxy.org/">http://config.privoxy.org/</ulink>
1308 (shortcut: <ulink url="http://p.p/">http://p.p/</ulink>),
1309 and then follow the link to <quote>View & Change the Current Configuration</quote>.
1310 (This is an internal page and does not require Internet access.)
1314 In fact, various aspects of <application>Privoxy</application>
1315 configuration can be viewed from this page, including
1316 current configuration parameters, source code version numbers,
1317 the browser's request headers, and <quote>actions</quote> that apply
1318 to a given URL. In addition to the actions file
1319 editor mentioned above, <application>Privoxy</application> can also
1320 be turned <quote>on</quote> and <quote>off</quote> (toggled) from this page.
1324 If you encounter problems, try loading the page without
1325 <application>Privoxy</application>. If that helps, enter the URL where
1326 you have the problems into <ulink url="http://p.p/show-url-info">the browser
1327 based rule tracing utility</ulink>. See which rules apply and why, and
1328 then try turning them off for that site one after the other, until the problem
1329 is gone. When you have found the culprit, you might want to turn the rest on
1334 If the above paragraph sounds gibberish to you, you might want to <link
1335 linkend="actions-file">read more about the actions concept</link>
1336 or even dive deep into the <link linkend="actionsanat">Appendix
1341 If you can't get rid of the problem at all, think you've found a bug in
1342 Privoxy, want to propose a new feature or smarter rules, please see the
1343 section <link linkend="contact"><quote>Contacting the
1344 Developers</quote></link> below.
1349 <!-- ~~~~~ New section ~~~~~ -->
1350 <sect2 id="cmdoptions">
1351 <title>Command Line Options</title>
1353 <application>Privoxy</application> may be invoked with the following
1354 command-line options:
1361 <emphasis>--config-test</emphasis>
1364 Exit after loading the configuration files before binding to
1365 the listen address. The exit code signals whether or not the
1366 configuration files have been successfully loaded.
1369 If the exit code is 1, at least one of the configuration files
1370 is invalid, if it is 0, all the configuration files have been
1371 successfully loaded (but may still contain errors that can
1372 currently only be detected at run time).
1375 This option doesn't affect the log setting, combination with
1376 <emphasis>--no-daemon</emphasis> is recommended if a configured
1377 log file shouldn't be used.
1382 <emphasis>--version</emphasis>
1385 Print version info and exit. Unix only.
1390 <emphasis>--help</emphasis>
1393 Print short usage info and exit. Unix only.
1398 <emphasis>--no-daemon</emphasis>
1401 Don't become a daemon, i.e. don't fork and become process group
1402 leader, and don't detach from controlling tty. Unix only.
1407 <emphasis>--pidfile FILE</emphasis>
1410 On startup, write the process ID to <emphasis>FILE</emphasis>. Delete the
1411 <emphasis>FILE</emphasis> on exit. Failure to create or delete the
1412 <emphasis>FILE</emphasis> is non-fatal. If no <emphasis>FILE</emphasis>
1413 option is given, no PID file will be used. Unix only.
1418 <emphasis>--user USER[.GROUP]</emphasis>
1421 After (optionally) writing the PID file, assume the user ID of
1422 <emphasis>USER</emphasis>, and if included the GID of GROUP. Exit if the
1423 privileges are not sufficient to do so. Unix only.
1428 <emphasis>--chroot</emphasis>
1431 Before changing to the user ID given in the <emphasis>--user</emphasis> option,
1432 chroot to that user's home directory, i.e. make the kernel pretend to the &my-app;
1433 process that the directory tree starts there. If set up carefully, this can limit
1434 the impact of possible vulnerabilities in &my-app; to the files contained in that hierarchy.
1440 <emphasis>--pre-chroot-nslookup hostname</emphasis>
1443 Specifies a hostname (for example www.privoxy.org) to look up before doing a chroot.
1444 On some systems, initializing the resolver library involves reading config files from
1445 /etc and/or loading additional shared libraries from /lib.
1446 On these systems, doing a hostname lookup before the chroot reduces
1447 the number of files that must be copied into the chroot tree.
1450 For fastest startup speed, a good value is a hostname that is not in /etc/hosts but that
1451 your local name server (listed in /etc/resolv.conf) can resolve without recursion
1452 (that is, without having to ask any other name servers). The hostname need not exist,
1453 but if it doesn't, an error message (which can be ignored) will be output.
1459 <emphasis>configfile</emphasis>
1462 If no <emphasis>configfile</emphasis> is included on the command line,
1463 <application>Privoxy</application> will look for a file named
1464 <quote>config</quote> in the current directory (except on Win32
1465 where it will look for <quote>config.txt</quote> instead). Specify
1466 full path to avoid confusion. If no config file is found,
1467 <application>Privoxy</application> will fail to start.
1474 On <application>MS Windows</application> only there are two additional
1475 command-line options to allow <application>Privoxy</application> to install and
1476 run as a <emphasis>service</emphasis>. See the
1477 <link linkend="installation-pack-win">Window Installation section</link>
1485 <!-- ~ End section ~ -->
1488 <!-- ~~~~~ New section ~~~~~ -->
1489 <sect1 id="configuration"><title>Privoxy Configuration</title>
1491 All <application>Privoxy</application> configuration is stored
1492 in text files. These files can be edited with a text editor.
1493 Many important aspects of <application>Privoxy</application> can
1494 also be controlled easily with a web browser.
1498 <!-- ~~~~~ New section ~~~~~ -->
1500 <sect2 id="control-with-webbrowser">
1501 <title>Controlling Privoxy with Your Web Browser</title>
1503 <application>Privoxy</application>'s user interface can be reached through the special
1504 URL <ulink url="http://config.privoxy.org/">http://config.privoxy.org/</ulink>
1505 (shortcut: <ulink url="http://p.p/">http://p.p/</ulink>),
1506 which is a built-in page and works without Internet access.
1507 You will see the following section:
1510 <!-- Needs to be put in a table and colorized -->
1511 <screen><!-- want the background color that goes with screen -->
1513 <bridgehead renderas="sect2"> Privoxy Menu</bridgehead>
1516 ▪ <ulink url="http://config.privoxy.org/show-status">View & change the current configuration</ulink>
1519 ▪ <ulink url="http://config.privoxy.org/show-version">View the source code version numbers</ulink>
1522 ▪ <ulink url="http://config.privoxy.org/show-request">View the request headers.</ulink>
1525 ▪ <ulink url="http://config.privoxy.org/show-url-info">Look up which actions apply to a URL and why</ulink>
1528 ▪ <ulink url="http://config.privoxy.org/toggle">Toggle Privoxy on or off</ulink>
1531 ▪ <ulink
1532 url="https://www.privoxy.org/&p-version;/user-manual/">Documentation</ulink>
1540 This should be self-explanatory. Note the first item leads to an editor for the
1541 <link linkend="actions-file">actions files</link>, which is where the ad, banner,
1542 cookie, and URL blocking magic is configured as well as other advanced features of
1543 <application>Privoxy</application>. This is an easy way to adjust various
1544 aspects of <application>Privoxy</application> configuration. The actions
1545 file, and other configuration files, are explained in detail below.
1549 <quote>Toggle Privoxy On or Off</quote> is handy for sites that might
1550 have problems with your current actions and filters. You can in fact use
1551 it as a test to see whether it is <application>Privoxy</application>
1552 causing the problem or not. <application>Privoxy</application> continues
1553 to run as a proxy in this case, but all manipulation is disabled, i.e.
1554 <application>Privoxy</application> acts like a normal forwarding proxy.
1558 Note that several of the features described above are disabled by default
1559 in <application>Privoxy</application> 3.0.7 beta and later.
1561 <ulink url="config.html">configuration file</ulink> to learn why
1562 and in which cases it's safe to enable them again.
1567 <!-- ~ End section ~ -->
1572 <!-- ~~~~~ New section ~~~~~ -->
1574 <sect2 id="confoverview">
1575 <title>Configuration Files Overview</title>
1577 For Unix, *BSD and Linux, all configuration files are located in
1578 <filename>/etc/privoxy/</filename> by default. For MS Windows, OS/2, and
1579 AmigaOS these are all in the same directory as the
1580 <application>Privoxy</application> executable. <![%p-not-stable;[ The name
1581 and number of configuration files has changed from previous versions, and is
1582 subject to change as development progresses.]]>
1586 The installed defaults provide a reasonable starting point, though
1587 some settings may be aggressive by some standards. For the time being, the
1588 principle configuration files are:
1595 The <link linkend="config">main configuration file</link> is named <filename>config</filename>
1596 on Linux, Unix, BSD, OS/2, and AmigaOS and <filename>config.txt</filename>
1597 on Windows. This is a required file.
1603 <filename>match-all.action</filename> is used to define which <quote>actions</quote>
1604 relating to banner-blocking, images, pop-ups, content modification, cookie handling
1605 etc should be applied by default. It should be the first actions file loaded.
1608 <filename>default.action</filename> defines many exceptions (both positive and negative)
1609 from the default set of actions that's configured in <filename>match-all.action</filename>.
1610 It should be the second actions file loaded and shouldn't be edited by the user.
1613 Multiple actions files may be defined in <filename>config</filename>. These
1614 are processed in the order they are defined. Local customizations and locally
1615 preferred exceptions to the default policies as defined in
1616 <filename>match-all.action</filename> (which you will most probably want
1617 to define sooner or later) are best applied in <filename>user.action</filename>,
1618 where you can preserve them across upgrades. The file isn't installed by all
1619 installers, but you can easily create it yourself with a text editor.
1622 There is also a web based editor that can be accessed from
1624 url="http://config.privoxy.org/show-status">http://config.privoxy.org/show-status</ulink>
1626 url="http://p.p/show-status">http://p.p/show-status</ulink>) for the
1627 various actions files.
1633 <quote>Filter files</quote> (the <link linkend="filter-file">filter
1634 file</link>) can be used to re-write the raw page content, including
1635 viewable text as well as embedded HTML and JavaScript, and whatever else
1636 lurks on any given web page. The filtering jobs are only pre-defined here;
1637 whether to apply them or not is up to the actions files.
1638 <filename>default.filter</filename> includes various filters made
1639 available for use by the developers. Some are much more intrusive than
1640 others, and all should be used with caution. You may define additional
1641 filter files in <filename>config</filename> as you can with
1642 actions files. We suggest <filename>user.filter</filename> for any
1643 locally defined filters or customizations.
1650 The syntax of the configuration and filter files may change between different
1651 Privoxy versions, unfortunately some enhancements cost backwards compatibility.
1652 <!-- Add link to documentation-->
1656 All files use the <quote><literal>#</literal></quote> character to denote a
1657 comment (the rest of the line will be ignored) and understand line continuation
1658 through placing a backslash ("<literal>\</literal>") as the very last character
1659 in a line. If the <literal>#</literal> is preceded by a backslash, it looses
1660 its special function. Placing a <literal>#</literal> in front of an otherwise
1661 valid configuration line to prevent it from being interpreted is called "commenting
1662 out" that line. Blank lines are ignored.
1666 The actions files and filter files
1667 can use Perl style <link linkend="regex">regular expressions</link> for
1668 maximum flexibility.
1672 After making any changes, there is no need to restart
1673 <application>Privoxy</application> in order for the changes to take
1674 effect. <application>Privoxy</application> detects such changes
1675 automatically. Note, however, that it may take one or two additional
1676 requests for the change to take effect. When changing the listening address
1677 of <application>Privoxy</application>, these <quote>wake up</quote> requests
1678 must obviously be sent to the <emphasis>old</emphasis> listening address.
1683 While under development, the configuration content is subject to change.
1684 The below documentation may not be accurate by the time you read this.
1685 Also, what constitutes a <quote>default</quote> setting, may change, so
1686 please check all your configuration files on important issues.
1692 <!-- ~ End section ~ -->
1695 <!-- ~~~~~~~~ New section Header ~~~~~~~~~ -->
1697 <!-- **************************************************** -->
1698 <!-- Include config.sgml here -->
1699 <!-- This is where the entire config file is detailed. -->
1701 <!-- end include -->
1704 <!-- ~ End section ~ -->
1708 <!-- ~~~~~~~~ New section Header ~~~~~~~~~ -->
1710 <sect1 id="actions-file"><title>Actions Files</title>
1714 XXX: similar descriptions are in the Configuration Files sections.
1715 We should only describe them at one place.
1718 The actions files are used to define what <emphasis>actions</emphasis>
1719 <application>Privoxy</application> takes for which URLs, and thus determines
1720 how ad images, cookies and various other aspects of HTTP content and
1721 transactions are handled, and on which sites (or even parts thereof).
1722 There are a number of such actions, with a wide range of functionality.
1723 Each action does something a little different.
1724 These actions give us a veritable arsenal of tools with which to exert
1725 our control, preferences and independence. Actions can be combined so that
1726 their effects are aggregated when applied against a given set of URLs.
1730 are three action files included with <application>Privoxy</application> with
1736 <filename>match-all.action</filename> - is used to define which
1737 <quote>actions</quote> relating to banner-blocking, images, pop-ups,
1738 content modification, cookie handling etc should be applied by default.
1739 It should be the first actions file loaded
1744 <filename>default.action</filename> - defines many exceptions (both
1745 positive and negative) from the default set of actions that's configured
1746 in <filename>match-all.action</filename>. It is a set of rules that should
1747 work reasonably well as-is for most users. This file is only supposed to
1748 be edited by the developers. It should be the second actions file loaded.
1753 <filename>user.action</filename> - is intended to be for local site
1754 preferences and exceptions. As an example, if your ISP or your bank
1755 has specific requirements, and need special handling, this kind of
1756 thing should go here. This file will not be upgraded.
1761 <guibutton>Edit</guibutton> <guibutton>Set to Cautious</guibutton> <guibutton>Set to Medium</guibutton> <guibutton>Set to Advanced</guibutton>
1764 These have increasing levels of aggressiveness <emphasis>and have no
1765 influence on your browsing unless you select them explicitly in the
1766 editor</emphasis>. A default installation should be pre-set to
1767 <literal>Cautious</literal>. New users should try this for a while before
1768 adjusting the settings to more aggressive levels. The more aggressive
1769 the settings, then the more likelihood there is of problems such as sites
1770 not working as they should.
1773 The <guibutton>Edit</guibutton> button allows you to turn each
1774 action on/off individually for fine-tuning. The <guibutton>Cautious</guibutton>
1775 button changes the actions list to low/safe settings which will activate
1776 ad blocking and a minimal set of &my-app;'s features, and subsequently
1777 there will be less of a chance for accidental problems. The
1778 <guibutton>Medium</guibutton> button sets the list to a medium level of
1779 other features and a low level set of privacy features. The
1780 <guibutton>Advanced</guibutton> button sets the list to a high level of
1781 ad blocking and medium level of privacy. See the chart below. The latter
1782 three buttons over-ride any changes via with the
1783 <guibutton>Edit</guibutton> button. More fine-tuning can be done in the
1784 lower sections of this internal page.
1787 While the actions file editor allows to enable these settings in all
1788 actions files, they are only supposed to be enabled in the first one
1789 to make sure you don't unintentionally overrule earlier rules.
1792 The default profiles, and their associated actions, as pre-defined in
1793 <filename>default.action</filename> are:
1795 <table frame=all><title>Default Configurations</title>
1796 <tgroup cols=4 align=left colsep=1 rowsep=1>
1797 <colspec colname=c1>
1798 <colspec colname=c2>
1799 <colspec colname=c3>
1800 <colspec colname=c4>
1803 <entry>Feature</entry>
1804 <entry>Cautious</entry>
1805 <entry>Medium</entry>
1806 <entry>Advanced</entry>
1811 <!-- <entry>f1</entry> -->
1812 <!-- <entry>f2</entry> -->
1813 <!-- <entry>f3</entry> -->
1814 <!-- <entry>f4</entry> -->
1820 <entry>Ad-blocking Aggressiveness</entry>
1821 <entry>medium</entry>
1827 <entry>Ad-filtering by size</entry>
1834 <entry>Ad-filtering by link</entry>
1840 <entry>Pop-up killing</entry>
1841 <entry>blocks only</entry>
1842 <entry>blocks only</entry>
1843 <entry>blocks only</entry>
1847 <entry>Privacy Features</entry>
1849 <entry>medium</entry>
1850 <entry>medium/high</entry>
1854 <entry>Cookie handling</entry>
1856 <entry>session-only</entry>
1861 <entry>Referer forging</entry>
1868 <entry>GIF de-animation</entry>
1875 <entry>Fast redirects</entry>
1882 <entry>HTML taming</entry>
1889 <entry>JavaScript taming</entry>
1896 <entry>Web-bug killing</entry>
1903 <entry>Image tag reordering</entry>
1917 The list of actions files to be used are defined in the main configuration
1918 file, and are processed in the order they are defined (e.g.
1919 <filename>default.action</filename> is typically processed before
1920 <filename>user.action</filename>). The content of these can all be viewed and
1922 url="http://config.privoxy.org/show-status">http://config.privoxy.org/show-status</ulink>.
1923 The over-riding principle when applying actions, is that the last action that
1924 matches a given URL wins. The broadest, most general rules go first
1925 (defined in <filename>default.action</filename>),
1926 followed by any exceptions (typically also in
1927 <filename>default.action</filename>), which are then followed lastly by any
1928 local preferences (typically in <emphasis>user</emphasis><filename>.action</filename>).
1929 Generally, <filename>user.action</filename> has the last word.
1933 An actions file typically has multiple sections. If you want to use
1934 <quote>aliases</quote> in an actions file, you have to place the (optional)
1935 <link linkend="aliases">alias section</link> at the top of that file.
1936 Then comes the default set of rules which will apply universally to all
1937 sites and pages (be <emphasis>very careful</emphasis> with using such a
1938 universal set in <filename>user.action</filename> or any other actions file after
1939 <filename>default.action</filename>, because it will override the result
1940 from consulting any previous file). And then below that,
1941 exceptions to the defined universal policies. You can regard
1942 <filename>user.action</filename> as an appendix to <filename>default.action</filename>,
1943 with the advantage that it is a separate file, which makes preserving your
1944 personal settings across <application>Privoxy</application> upgrades easier.
1948 Actions can be used to block anything you want, including ads, banners, or
1949 just some obnoxious URL whose content you would rather not see. Cookies can be accepted
1950 or rejected, or accepted only during the current browser session (i.e. not
1951 written to disk), content can be modified, some JavaScripts tamed, user-tracking
1952 fooled, and much more. See below for a <link linkend="actions">complete list
1956 <!-- ~~~~~ New section ~~~~~ -->
1957 <sect2 id="right-mix">
1958 <title>Finding the Right Mix</title>
1960 Note that some <link linkend="actions">actions</link>, like cookie suppression
1961 or script disabling, may render some sites unusable that rely on these
1962 techniques to work properly. Finding the right mix of actions is not always easy and
1963 certainly a matter of personal taste. And, things can always change, requiring
1964 refinements in the configuration. In general, it can be said that the more
1965 <quote>aggressive</quote> your default settings (in the top section of the
1966 actions file) are, the more exceptions for <quote>trusted</quote> sites you
1967 will have to make later. If, for example, you want to crunch all cookies per
1968 default, you'll have to make exceptions from that rule for sites that you
1969 regularly use and that require cookies for actually useful purposes, like maybe
1970 your bank, favorite shop, or newspaper.
1974 We have tried to provide you with reasonable rules to start from in the
1975 distribution actions files. But there is no general rule of thumb on these
1976 things. There just are too many variables, and sites are constantly changing.
1977 Sooner or later you will want to change the rules (and read this chapter again :).
1981 <!-- ~~~~~ New section ~~~~~ -->
1982 <sect2 id="how-to-edit">
1983 <title>How to Edit</title>
1985 The easiest way to edit the actions files is with a browser by
1986 using our browser-based editor, which can be reached from <ulink
1987 url="http://config.privoxy.org/show-status">http://config.privoxy.org/show-status</ulink>.
1988 Note: the config file option <link
1989 linkend="enable-edit-actions">enable-edit-actions</link> must be enabled for
1990 this to work. The editor allows both fine-grained control over every single
1991 feature on a per-URL basis, and easy choosing from wholesale sets of defaults
1992 like <quote>Cautious</quote>, <quote>Medium</quote> or
1993 <quote>Advanced</quote>. Warning: the <quote>Advanced</quote> setting is more
1994 aggressive, and will be more likely to cause problems for some sites.
1995 Experienced users only!
1999 If you prefer plain text editing to GUIs, you can of course also directly edit the
2000 the actions files with your favorite text editor. Look at
2001 <filename>default.action</filename> which is richly commented with many
2007 <sect2 id="actions-apply">
2008 <title>How Actions are Applied to Requests</title>
2010 Actions files are divided into sections. There are special sections,
2011 like the <quote><link linkend="aliases">alias</link></quote> sections which will
2012 be discussed later. For now let's concentrate on regular sections: They have a
2013 heading line (often split up to multiple lines for readability) which consist
2014 of a list of actions, separated by whitespace and enclosed in curly braces.
2015 Below that, there is a list of URL and tag patterns, each on a separate line.
2019 To determine which actions apply to a request, the URL of the request is
2020 compared to all URL patterns in each <quote>action file</quote>.
2021 Every time it matches, the list of applicable actions for the request is
2022 incrementally updated, using the heading of the section in which the
2023 pattern is located. The same is done again for tags and tag patterns later on.
2027 If multiple applying sections set the same action differently,
2028 the last match wins. If not, the effects are aggregated.
2029 E.g. a URL might match a regular section with a heading line of <literal>{
2030 +<link linkend="handle-as-image">handle-as-image</link> }</literal>,
2031 then later another one with just <literal>{
2032 +<link linkend="block">block</link> }</literal>, resulting
2033 in <emphasis>both</emphasis> actions to apply. And there may well be
2034 cases where you will want to combine actions together. Such a section then
2039 { +<literal>handle-as-image</literal> +<literal>block{Banner ads.}</literal> }
2040 # Block these as if they were images. Send no block page.
2042 media.example.com/.*banners
2043 .example.com/images/ads/</screen>
2046 You can trace this process for URL patterns and any given URL by visiting <ulink
2047 url="http://config.privoxy.org/show-url-info">http://config.privoxy.org/show-url-info</ulink>.
2051 Examples and more detail on this is provided in the Appendix, <link linkend="ACTIONSANAT">
2052 Troubleshooting: Anatomy of an Action</link> section.
2056 <!-- ~~~~~ New section ~~~~~ -->
2057 <sect2 id="af-patterns">
2058 <title>Patterns</title>
2060 As mentioned, <application>Privoxy</application> uses <quote>patterns</quote>
2061 to determine what <emphasis>actions</emphasis> might apply to which sites and
2062 pages your browser attempts to access. These <quote>patterns</quote> use wild
2063 card type <emphasis>pattern</emphasis> matching to achieve a high degree of
2064 flexibility. This allows one expression to be expanded and potentially match
2065 against many similar patterns.
2069 Generally, an URL pattern has the form
2070 <literal><host><port>/<path></literal>, where the
2071 <literal><host></literal>, the <literal><port></literal>
2072 and the <literal><path></literal> are optional. (This is why the special
2073 <literal>/</literal> pattern matches all URLs). Note that the protocol
2074 portion of the URL pattern (e.g. <literal>http://</literal>) should
2075 <emphasis>not</emphasis> be included in the pattern. This is assumed already!
2078 The pattern matching syntax is different for the host and path parts of
2079 the URL. The host part uses a simple globbing type matching technique,
2080 while the path part uses more flexible
2081 <ulink url="http://en.wikipedia.org/wiki/Regular_expressions"><quote>Regular
2082 Expressions</quote></ulink> (POSIX 1003.2).
2085 The port part of a pattern is a decimal port number preceded by a colon
2086 (<literal>:</literal>). If the host part contains a numerical IPv6 address,
2087 it has to be put into angle brackets
2088 (<literal><</literal>, <literal>></literal>).
2093 <term><literal>www.example.com/</literal></term>
2096 is a host-only pattern and will match any request to <literal>www.example.com</literal>,
2097 regardless of which document on that server is requested. So ALL pages in
2098 this domain would be covered by the scope of this action. Note that a
2099 simple <literal>example.com</literal> is different and would NOT match.
2104 <term><literal>www.example.com</literal></term>
2107 means exactly the same. For host-only patterns, the trailing <literal>/</literal> may
2113 <term><literal>www.example.com/index.html</literal></term>
2116 matches all the documents on <literal>www.example.com</literal>
2117 whose name starts with <literal>/index.html</literal>.
2122 <term><literal>www.example.com/index.html$</literal></term>
2125 matches only the single document <literal>/index.html</literal>
2126 on <literal>www.example.com</literal>.
2131 <term><literal>/index.html$</literal></term>
2134 matches the document <literal>/index.html</literal>, regardless of the domain,
2135 i.e. on <emphasis>any</emphasis> web server anywhere.
2140 <term><literal>/</literal></term>
2143 Matches any URL because there's no requirement for either the
2144 domain or the path to match anything.
2149 <term><literal>:8000/</literal></term>
2152 Matches any URL pointing to TCP port 8000.
2157 <term><literal>10.0.0.1/</literal></term>
2160 Matches any URL with the host address <literal>10.0.0.1</literal>.
2161 (Note that the real URL uses plain brackets, not angle brackets.)
2166 <term><literal><2001:db8::1>/</literal></term>
2169 Matches any URL with the host address <literal>2001:db8::1</literal>.
2170 (Note that the real URL uses plain brackets, not angle brackets.)
2175 <term><literal>index.html</literal></term>
2178 matches nothing, since it would be interpreted as a domain name and
2179 there is no top-level domain called <literal>.html</literal>. So its
2187 <!-- ~~~~~ New section ~~~~~ -->
2188 <sect3 id="host-pattern"><title>The Host Pattern</title>
2191 The matching of the host part offers some flexible options: if the
2192 host pattern starts or ends with a dot, it becomes unanchored at that end.
2193 The host pattern is often referred to as domain pattern as it is usually
2194 used to match domain names and not IP addresses.
2200 <term><literal>.example.com</literal></term>
2203 matches any domain with first-level domain <literal>com</literal>
2204 and second-level domain <literal>example</literal>.
2205 For example <literal>www.example.com</literal>,
2206 <literal>example.com</literal> and <literal>foo.bar.baz.example.com</literal>.
2207 Note that it wouldn't match if the second-level domain was <literal>another-example</literal>.
2212 <term><literal>www.</literal></term>
2215 matches any domain that <emphasis>STARTS</emphasis> with
2216 <literal>www.</literal> (It also matches the domain
2217 <literal>www</literal> but most of the time that doesn't matter.)
2222 <term><literal>.example.</literal></term>
2225 matches any domain that <emphasis>CONTAINS</emphasis> <literal>.example.</literal>.
2226 And, by the way, also included would be any files or documents that exist
2227 within that domain since no path limitations are specified. (Correctly
2228 speaking: It matches any FQDN that contains <literal>example</literal> as
2229 a domain.) This might be <literal>www.example.com</literal>,
2230 <literal>news.example.de</literal>, or
2231 <literal>www.example.net/cgi/testing.pl</literal> for instance. All these
2239 Additionally, there are wild-cards that you can use in the domain names
2240 themselves. These work similarly to shell globbing type wild-cards:
2241 <quote>*</quote> represents zero or more arbitrary characters (this is
2243 <ulink url="http://en.wikipedia.org/wiki/Regular_expressions"><quote>Regular
2244 Expression</quote></ulink> based syntax of <quote>.*</quote>),
2245 <quote>?</quote> represents any single character (this is equivalent to the
2246 regular expression syntax of a simple <quote>.</quote>), and you can define
2247 <quote>character classes</quote> in square brackets which is similar to
2248 the same regular expression technique. All of this can be freely mixed:
2253 <term><literal>ad*.example.com</literal></term>
2256 matches <quote>adserver.example.com</quote>,
2257 <quote>ads.example.com</quote>, etc but not <quote>sfads.example.com</quote>
2262 <term><literal>*ad*.example.com</literal></term>
2265 matches all of the above, and then some.
2270 <term><literal>.?pix.com</literal></term>
2273 matches <literal>www.ipix.com</literal>,
2274 <literal>pictures.epix.com</literal>, <literal>a.b.c.d.e.upix.com</literal> etc.
2279 <term><literal>www[1-9a-ez].example.c*</literal></term>
2282 matches <literal>www1.example.com</literal>,
2283 <literal>www4.example.cc</literal>, <literal>wwwd.example.cy</literal>,
2284 <literal>wwwz.example.com</literal> etc., but <emphasis>not</emphasis>
2285 <literal>wwww.example.com</literal>.
2292 While flexible, this is not the sophistication of full regular expression based syntax.
2297 <!-- ~ End section ~ -->
2300 <!-- ~~~~~ New section ~~~~~ -->
2301 <sect3 id="path-pattern"><title>The Path Pattern</title>
2304 <application>Privoxy</application> uses <quote>modern</quote> POSIX 1003.2
2305 <ulink url="http://en.wikipedia.org/wiki/Regular_expressions"><quote>Regular
2306 Expressions</quote></ulink> for matching the path portion (after the slash),
2307 and is thus more flexible.
2311 There is an <link linkend="regex">Appendix</link> with a brief quick-start into regular
2312 expressions, you also might want to have a look at your operating system's documentation
2313 on regular expressions (try <literal>man re_format</literal>).
2317 Note that the path pattern is automatically left-anchored at the <quote>/</quote>,
2318 i.e. it matches as if it would start with a <quote>^</quote> (regular expression speak
2319 for the beginning of a line).
2323 Please also note that matching in the path is <emphasis>CASE INSENSITIVE</emphasis>
2324 by default, but you can switch to case sensitive at any point in the pattern by using the
2325 <quote>(?-i)</quote> switch: <literal>www.example.com/(?-i)PaTtErN.*</literal> will match
2326 only documents whose path starts with <literal>PaTtErN</literal> in
2327 <emphasis>exactly</emphasis> this capitalization.
2332 <term><literal>.example.com/.*</literal></term>
2335 Is equivalent to just <quote>.example.com</quote>, since any documents
2336 within that domain are matched with or without the <quote>.*</quote>
2337 regular expression. This is redundant
2342 <term><literal>.example.com/.*/index.html$</literal></term>
2345 Will match any page in the domain of <quote>example.com</quote> that is
2346 named <quote>index.html</quote>, and that is part of some path. For
2347 example, it matches <quote>www.example.com/testing/index.html</quote> but
2348 NOT <quote>www.example.com/index.html</quote> because the regular
2349 expression called for at least two <quote>/'s</quote>, thus the path
2350 requirement. It also would match
2351 <quote>www.example.com/testing/index_html</quote>, because of the
2352 special meta-character <quote>.</quote>.
2357 <term><literal>.example.com/(.*/)?index\.html$</literal></term>
2360 This regular expression is conditional so it will match any page
2361 named <quote>index.html</quote> regardless of path which in this case can
2362 have one or more <quote>/'s</quote>. And this one must contain exactly
2363 <quote>.html</quote> (and end with that!).
2368 <term><literal>.example.com/(.*/)(ads|banners?|junk)</literal></term>
2371 This regular expression will match any path of <quote>example.com</quote>
2372 that contains any of the words <quote>ads</quote>, <quote>banner</quote>,
2373 <quote>banners</quote> (because of the <quote>?</quote>) or <quote>junk</quote>.
2374 The path does not have to end in these words, just contain them.
2375 The path has to contain at least two slashes (including the one at the beginning).
2380 <term><literal>.example.com/(.*/)(ads|banners?|junk)/.*\.(jpe?g|gif|png)$</literal></term>
2383 This is very much the same as above, except now it must end in either
2384 <quote>.jpg</quote>, <quote>.jpeg</quote>, <quote>.gif</quote> or <quote>.png</quote>. So this
2385 one is limited to common image formats.
2392 There are many, many good examples to be found in <filename>default.action</filename>,
2393 and more tutorials below in <link linkend="regex">Appendix on regular expressions</link>.
2398 <!-- ~ End section ~ -->
2401 <!-- ~~~~~ New section ~~~~~ -->
2402 <sect3 id="tag-pattern"><title>The Request Tag Pattern</title>
2405 Request tag patterns are used to change the applying actions based on the
2406 request's tags. Tags can be created based on HTTP headers with either
2407 the <link linkend="CLIENT-HEADER-TAGGER">client-header-tagger</link>
2408 or the <link linkend="SERVER-HEADER-TAGGER">server-header-tagger</link> action.
2412 Request tag patterns have to start with <quote>TAG:</quote>, so &my-app;
2413 can tell them apart from other patterns. Everything after the colon
2414 including white space, is interpreted as a regular expression with
2415 path pattern syntax, except that tag patterns aren't left-anchored
2416 automatically (&my-app; doesn't silently add a <quote>^</quote>,
2417 you have to do it yourself if you need it).
2421 To match all requests that are tagged with <quote>foo</quote>
2422 your pattern line should be <quote>TAG:^foo$</quote>,
2423 <quote>TAG:foo</quote> would work as well, but it would also
2424 match requests whose tags contain <quote>foo</quote> somewhere.
2425 <quote>TAG: foo</quote> wouldn't work as it requires white space.
2429 Sections can contain URL and request tag patterns at the same time,
2430 but request tag patterns are checked after the URL patterns and thus
2431 always overrule them, even if they are located before the URL patterns.
2435 Once a new request tag is added, Privoxy checks right away if it's matched by one
2436 of the request tag patterns and updates the action settings accordingly. As a result
2437 request tags can be used to activate other tagger actions, as long as these other
2438 taggers look for headers that haven't already be parsed.
2442 For example you could tag client requests which use the
2443 <literal>POST</literal> method,
2444 then use this tag to activate another tagger that adds a tag if cookies
2445 are sent, and then use a block action based on the cookie tag. This allows
2446 the outcome of one action, to be input into a subsequent action. However if
2447 you'd reverse the position of the described taggers, and activated the
2448 method tagger based on the cookie tagger, no method tags would be created.
2449 The method tagger would look for the request line, but at the time
2450 the cookie tag is created, the request line has already been parsed.
2454 While this is a limitation you should be aware of, this kind of
2455 indirection is seldom needed anyway and even the example doesn't
2456 make too much sense.
2461 <!-- ~~~~~ New section ~~~~~ -->
2462 <sect3 id="negative-tag-patterns"><title>The Negative Request Tag Patterns</title>
2465 To match requests that do not have a certain request tag, specify a negative tag pattern
2466 by prefixing the tag pattern line with either <quote>NO-REQUEST-TAG:</quote>
2467 or <quote>NO-RESPONSE-TAG:</quote> instead of <quote>TAG:</quote>.
2471 Negative request tag patterns created with <quote>NO-REQUEST-TAG:</quote> are checked
2472 after all client headers are scanned, the ones created with <quote>NO-RESPONSE-TAG:</quote>
2473 are checked after all server headers are scanned. In both cases all the created
2474 tags are considered.
2478 <!-- ~~~~~ New section ~~~~~ -->
2479 <sect3 id="client-tag-pattern"><title>The Client Tag Pattern</title>
2481 <!-- XXX: This section contains duplicates content from the
2482 client-specific-tag documentation. -->
2486 This is an experimental feature. The syntax is likely to change in future versions.
2491 Client tag patterns are not set based on HTTP headers but based on
2492 the client's IP address. Users can enable them themselves, but the
2493 Privoxy admin controls which tags are available and what their effect
2498 After a client-specific tag has been defined with the
2499 <link linkend="client-specific-tag">client-specific-tag</link>,
2500 directive, action sections can be activated based on the tag by using a
2501 CLIENT-TAG pattern. The CLIENT-TAG pattern is evaluated at the same priority
2502 as URL patterns, as a result the last matching pattern wins. Tags that
2503 are created based on client or server headers are evaluated later on
2504 and can overrule CLIENT-TAG and URL patterns!
2507 The tag is set for all requests that come from clients that requested
2508 it to be set. Note that "clients" are differentiated by IP address,
2509 if the IP address changes the tag has to be requested again.
2512 Clients can request tags to be set by using the CGI interface <ulink
2513 url="http://config.privoxy.org/client-tags">http://config.privoxy.org/client-tags</ulink>.
2521 # If the admin defined the client-specific-tag circumvent-blocks,
2522 # and the request comes from a client that previously requested
2523 # the tag to be set, overrule all previous +block actions that
2524 # are enabled based on URL to CLIENT-TAG patterns.
2526 CLIENT-TAG:^circumvent-blocks$
2528 # This section is not overruled because it's located after
2530 {+block{Nobody is supposed to request this.}}
2531 example.org/blocked-example-page</screen>
2537 <!-- ~ End section ~ -->
2540 <!-- ~~~~~ New section ~~~~~ -->
2542 <sect2 id="actions">
2543 <title>Actions</title>
2545 All actions are disabled by default, until they are explicitly enabled
2546 somewhere in an actions file. Actions are turned on if preceded with a
2547 <quote>+</quote>, and turned off if preceded with a <quote>-</quote>. So a
2548 <literal>+action</literal> means <quote>do that action</quote>, e.g.
2549 <literal>+block</literal> means <quote>please block URLs that match the
2550 following patterns</quote>, and <literal>-block</literal> means <quote>don't
2551 block URLs that match the following patterns, even if <literal>+block</literal>
2552 previously applied.</quote>
2556 Again, actions are invoked by placing them on a line, enclosed in curly braces and
2557 separated by whitespace, like in
2558 <literal>{+some-action -some-other-action{some-parameter}}</literal>,
2559 followed by a list of URL patterns, one per line, to which they apply.
2560 Together, the actions line and the following pattern lines make up a section
2561 of the actions file.
2565 Actions fall into three categories:
2571 Boolean, i.e the action can only be <quote>enabled</quote> or
2572 <quote>disabled</quote>. Syntax:
2575 +<replaceable class="function">name</replaceable> # enable action <replaceable class="parameter">name</replaceable>
2576 -<replaceable class="function">name</replaceable> # disable action <replaceable class="parameter">name</replaceable></screen>
2578 Example: <literal>+handle-as-image</literal>
2585 Parameterized, where some value is required in order to enable this type of action.
2589 +<replaceable class="function">name</replaceable>{<replaceable class="parameter">param</replaceable>} # enable action and set parameter to <replaceable class="parameter">param</replaceable>,
2590 # overwriting parameter from previous match if necessary
2591 -<replaceable class="function">name</replaceable> # disable action. The parameter can be omitted</screen>
2593 Note that if the URL matches multiple positive forms of a parameterized action,
2594 the last match wins, i.e. the params from earlier matches are simply ignored.
2597 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>
2603 Multi-value. These look exactly like parameterized actions,
2604 but they behave differently: If the action applies multiple times to the
2605 same URL, but with different parameters, <emphasis>all</emphasis> the parameters
2606 from <emphasis>all</emphasis> matches are remembered. This is used for actions
2607 that can be executed for the same request repeatedly, like adding multiple
2608 headers, or filtering through multiple filters. Syntax:
2611 +<replaceable class="function">name</replaceable>{<replaceable class="parameter">param</replaceable>} # enable action and add <replaceable class="parameter">param</replaceable> to the list of parameters
2612 -<replaceable class="function">name</replaceable>{<replaceable class="parameter">param</replaceable>} # remove the parameter <replaceable class="parameter">param</replaceable> from the list of parameters
2613 # If it was the last one left, disable the action.
2614 <replaceable class="parameter">-name</replaceable> # disable this action completely and remove all parameters from the list</screen>
2616 Examples: <literal>+add-header{X-Fun-Header: Some text}</literal> and
2617 <literal>+filter{html-annoyances}</literal>
2624 If nothing is specified in any actions file, no <quote>actions</quote> are
2625 taken. So in this case <application>Privoxy</application> would just be a
2626 normal, non-blocking, non-filtering proxy. You must specifically enable the
2627 privacy and blocking features you need (although the provided default actions
2628 files will give a good starting point).
2632 Later defined action sections always over-ride earlier ones of the same type.
2633 So exceptions to any rules you make, should come in the latter part of the file (or
2634 in a file that is processed later when using multiple actions files such
2635 as <filename>user.action</filename>). For multi-valued actions, the actions
2636 are applied in the order they are specified. Actions files are processed in
2637 the order they are defined in <filename>config</filename> (the default
2638 installation has three actions files). It also quite possible for any given
2639 URL to match more than one <quote>pattern</quote> (because of wildcards and
2640 regular expressions), and thus to trigger more than one set of actions! Last
2644 <!-- start actions listing -->
2646 The list of valid <application>Privoxy</application> actions are:
2650 <!-- ********************************************************** -->
2651 <!-- Please note the below defined actions use id's that are -->
2652 <!-- probably linked from other places, so please don't change. -->
2654 <!-- ********************************************************** -->
2657 <!-- ~~~~~ New section ~~~~~ -->
2659 <sect3 renderas="sect4" id="add-header">
2660 <title>add-header</title>
2664 <term>Typical use:</term>
2666 <para>Confuse log analysis, custom applications</para>
2671 <term>Effect:</term>
2674 Sends a user defined HTTP header to the web server.
2681 <!-- boolean, parameterized, Multi-value -->
2683 <para>Multi-value.</para>
2688 <term>Parameter:</term>
2691 Any string value is possible. Validity of the defined HTTP headers is not checked.
2692 It is recommended that you use the <quote><literal>X-</literal></quote> prefix
2702 This action may be specified multiple times, in order to define multiple
2703 headers. This is rarely needed for the typical user. If you don't know what
2704 <quote>HTTP headers</quote> are, you definitely don't need to worry about this
2708 Headers added by this action are not modified by other actions.
2714 <term>Example usage:</term>
2716 <screen># Add a DNT ("Do not track") header to all requests,
2717 # event to those that already have one.
2719 # This is just an example, not a recommendation.
2721 # There is no reason to believe that user-tracking websites care
2722 # about the DNT header and depending on the User-Agent, adding the
2723 # header may make user-tracking easier.
2724 {+add-header{DNT: 1}}
2732 <!-- ~~~~~ New section ~~~~~ -->
2733 <sect3 renderas="sect4" id="block">
2734 <title>block</title>
2738 <term>Typical use:</term>
2740 <para>Block ads or other unwanted content</para>
2745 <term>Effect:</term>
2748 Requests for URLs to which this action applies are blocked, i.e. the
2749 requests are trapped by &my-app; and the requested URL is never retrieved,
2750 but is answered locally with a substitute page or image, as determined by
2752 linkend="handle-as-image">handle-as-image</link></literal>,
2754 linkend="set-image-blocker">set-image-blocker</link></literal>, and
2756 linkend="handle-as-empty-document">handle-as-empty-document</link></literal> actions.
2764 <!-- boolean, parameterized, Multi-value -->
2766 <para>Parameterized.</para>
2771 <term>Parameter:</term>
2773 <para>A block reason that should be given to the user.</para>
2781 <application>Privoxy</application> sends a special <quote>BLOCKED</quote> page
2782 for requests to blocked pages. This page contains the block reason given as
2783 parameter, a link to find out why the block action applies, and a click-through
2784 to the blocked content (the latter only if the force feature is available and
2788 A very important exception occurs if <emphasis>both</emphasis>
2789 <literal>block</literal> and <literal><link linkend="handle-as-image">handle-as-image</link></literal>,
2790 apply to the same request: it will then be replaced by an image. If
2791 <literal><link linkend="set-image-blocker">set-image-blocker</link></literal>
2792 (see below) also applies, the type of image will be determined by its parameter,
2793 if not, the standard checkerboard pattern is sent.
2796 It is important to understand this process, in order
2797 to understand how <application>Privoxy</application> deals with
2798 ads and other unwanted content. Blocking is a core feature, and one
2799 upon which various other features depend.
2802 The <literal><link linkend="filter">filter</link></literal>
2803 action can perform a very similar task, by <quote>blocking</quote>
2804 banner images and other content through rewriting the relevant URLs in the
2805 document's HTML source, so they don't get requested in the first place.
2806 Note that this is a totally different technique, and it's easy to confuse the two.
2812 <term>Example usage (section):</term>
2814 <screen>{+block{No nasty stuff for you.}}
2815 # Block and replace with "blocked" page
2816 .nasty-stuff.example.com
2818 {+block{Doubleclick banners.} +handle-as-image}
2819 # Block and replace with image
2823 {+block{Layered ads.} +handle-as-empty-document}
2824 # Block and then ignore
2825 adserver.example.net/.*\.js$</screen>
2834 <!-- ~~~~~ New section ~~~~~ -->
2835 <sect3 renderas="sect4" id="change-x-forwarded-for">
2836 <title>change-x-forwarded-for</title>
2840 <term>Typical use:</term>
2842 <para>Improve privacy by not forwarding the source of the request in the HTTP headers.</para>
2847 <term>Effect:</term>
2850 Deletes the <quote>X-Forwarded-For:</quote> HTTP header from the client request,
2858 <!-- Boolean, Parameterized, Multi-value -->
2860 <para>Parameterized.</para>
2865 <term>Parameter:</term>
2869 <para><quote>block</quote> to delete the header.</para>
2873 <quote>add</quote> to create the header (or append
2874 the client's IP address to an already existing one).
2885 It is safe and recommended to use <literal>block</literal>.
2888 Forwarding the source address of the request may make
2889 sense in some multi-user setups but is also a privacy risk.
2894 <term>Example usage:</term>
2896 <screen>+change-x-forwarded-for{block}</screen>
2902 <!-- ~~~~~ New section ~~~~~ -->
2903 <sect3 renderas="sect4" id="client-header-filter">
2904 <title>client-header-filter</title>
2908 <term>Typical use:</term>
2911 Rewrite or remove single client headers.
2917 <term>Effect:</term>
2920 All client headers to which this action applies are filtered on-the-fly through
2921 the specified regular expression based substitutions.
2928 <!-- boolean, parameterized, Multi-value -->
2930 <para>Multi-value.</para>
2935 <term>Parameter:</term>
2938 The name of a client-header filter, as defined in one of the
2939 <link linkend="filter-file">filter files</link>.
2948 Client-header filters are applied to each header on its own, not to
2949 all at once. This makes it easier to diagnose problems, but on the downside
2950 you can't write filters that only change header x if header y's value is z.
2951 You can do that by using tags though.
2954 Client-header filters are executed after the other header actions have finished
2955 and use their output as input.
2958 If the request URI gets changed, &my-app; will detect that and use the new
2959 one. This can be used to rewrite the request destination behind the client's
2960 back, for example to specify a Tor exit relay for certain requests.
2963 Please refer to the <link linkend="filter-file">filter file chapter</link>
2964 to learn which client-header filters are available by default, and how to
2972 <term>Example usage (section):</term>
2975 # Hide Tor exit notation in Host and Referer Headers
2976 {+client-header-filter{hide-tor-exit-notation}}
2986 <!-- ~~~~~ New section ~~~~~ -->
2987 <sect3 renderas="sect4" id="client-header-tagger">
2988 <title>client-header-tagger</title>
2992 <term>Typical use:</term>
2995 Block requests based on their headers.
3001 <term>Effect:</term>
3004 Client headers to which this action applies are filtered on-the-fly through
3005 the specified regular expression based substitutions, the result is used as
3013 <!-- boolean, parameterized, Multi-value -->
3015 <para>Multi-value.</para>
3020 <term>Parameter:</term>
3023 The name of a client-header tagger, as defined in one of the
3024 <link linkend="filter-file">filter files</link>.
3033 Client-header taggers are applied to each header on its own,
3034 and as the header isn't modified, each tagger <quote>sees</quote>
3038 Client-header taggers are the first actions that are executed
3039 and their tags can be used to control every other action.
3045 <term>Example usage (section):</term>
3048 # Tag every request with the User-Agent header
3049 {+client-header-tagger{user-agent}}
3052 # Tagging itself doesn't change the action
3053 # settings, sections with TAG patterns do:
3055 # If it's a download agent, use a different forwarding proxy,
3056 # show the real User-Agent and make sure resume works.
3057 {+forward-override{forward-socks5 10.0.0.2:2222 .} \
3058 -hide-if-modified-since \
3059 -overwrite-last-modified \
3064 TAG:^User-Agent: NetBSD-ftp/
3065 TAG:^User-Agent: Novell ZYPP Installer
3066 TAG:^User-Agent: RPM APT-HTTP/
3067 TAG:^User-Agent: fetch libfetch/
3068 TAG:^User-Agent: Ubuntu APT-HTTP/
3069 TAG:^User-Agent: MPlayer/
3073 # Tag all requests with the Range header set
3074 {+client-header-tagger{range-requests}}
3077 # Disable filtering for the tagged requests.
3079 # With filtering enabled Privoxy would remove the Range headers
3080 # to be able to filter the whole response. The downside is that
3081 # it prevents clients from resuming downloads or skipping over
3082 # parts of multimedia files.
3083 {-filter -deanimate-gifs}
3088 # Tag all requests with the client IP address
3090 # (Technically the client IP address isn't included in the
3091 # client headers but client-header taggers can set it anyway.
3092 # For details see the tagger in default.filter)
3093 {+client-header-tagger{client-ip-address}}
3096 # Change forwarding settings for requests coming from address 10.0.0.1
3097 {+forward-override{forward-socks5 127.0.1.2:2222 .}}
3098 TAG:^IP-ADDRESS: 10\.0\.0\.1$
3107 <!-- ~~~~~ New section ~~~~~ -->
3108 <sect3 renderas="sect4" id="content-type-overwrite">
3109 <title>content-type-overwrite</title>
3113 <term>Typical use:</term>
3115 <para>Stop useless download menus from popping up, or change the browser's rendering mode</para>
3120 <term>Effect:</term>
3123 Replaces the <quote>Content-Type:</quote> HTTP server header.
3130 <!-- Boolean, Parameterized, Multi-value -->
3132 <para>Parameterized.</para>
3137 <term>Parameter:</term>
3149 The <quote>Content-Type:</quote> HTTP server header is used by the
3150 browser to decide what to do with the document. The value of this
3151 header can cause the browser to open a download menu instead of
3152 displaying the document by itself, even if the document's format is
3153 supported by the browser.
3156 The declared content type can also affect which rendering mode
3157 the browser chooses. If XHTML is delivered as <quote>text/html</quote>,
3158 many browsers treat it as yet another broken HTML document.
3159 If it is send as <quote>application/xml</quote>, browsers with
3160 XHTML support will only display it, if the syntax is correct.
3163 If you see a web site that proudly uses XHTML buttons, but sets
3164 <quote>Content-Type: text/html</quote>, you can use &my-app;
3165 to overwrite it with <quote>application/xml</quote> and validate
3166 the web master's claim inside your XHTML-supporting browser.
3167 If the syntax is incorrect, the browser will complain loudly.
3170 You can also go the opposite direction: if your browser prints
3171 error messages instead of rendering a document falsely declared
3172 as XHTML, you can overwrite the content type with
3173 <quote>text/html</quote> and have it rendered as broken HTML document.
3176 By default <literal>content-type-overwrite</literal> only replaces
3177 <quote>Content-Type:</quote> headers that look like some kind of text.
3178 If you want to overwrite it unconditionally, you have to combine it with
3179 <literal><link linkend="force-text-mode">force-text-mode</link></literal>.
3180 This limitation exists for a reason, think twice before circumventing it.
3183 Most of the time it's easier to replace this action with a custom
3184 <literal><link linkend="server-header-filter">server-header filter</link></literal>.
3185 It allows you to activate it for every document of a certain site and it will still
3186 only replace the content types you aimed at.
3189 Of course you can apply <literal>content-type-overwrite</literal>
3190 to a whole site and then make URL based exceptions, but it's a lot
3191 more work to get the same precision.
3197 <term>Example usage (sections):</term>
3199 <screen># Check if www.example.net/ really uses valid XHTML
3200 { +content-type-overwrite{application/xml} }
3203 # but leave the content type unmodified if the URL looks like a style sheet
3204 {-content-type-overwrite}
3205 www.example.net/.*\.css$
3206 www.example.net/.*style
3214 <!-- ~~~~~ New section ~~~~~ -->
3215 <sect3 renderas="sect4" id="crunch-client-header">
3219 <title>crunch-client-header</title>
3223 <term>Typical use:</term>
3225 <para>Remove a client header <application>Privoxy</application> has no dedicated action for.</para>
3230 <term>Effect:</term>
3233 Deletes every header sent by the client that contains the string the user supplied as parameter.
3240 <!-- Boolean, Parameterized, Multi-value -->
3242 <para>Parameterized.</para>
3247 <term>Parameter:</term>
3259 This action allows you to block client headers for which no dedicated
3260 <application>Privoxy</application> action exists.
3261 <application>Privoxy</application> will remove every client header that
3262 contains the string you supplied as parameter.
3265 Regular expressions are <emphasis>not supported</emphasis> and you can't
3266 use this action to block different headers in the same request, unless
3267 they contain the same string.
3270 <literal>crunch-client-header</literal> is only meant for quick tests.
3271 If you have to block several different headers, or only want to modify
3272 parts of them, you should use a
3273 <literal><link linkend="client-header-filter">client-header filter</link></literal>.
3277 Don't block any header without understanding the consequences.
3284 <term>Example usage (section):</term>
3286 <screen># Block the non-existent "Privacy-Violation:" client header
3287 { +crunch-client-header{Privacy-Violation:} }
3296 <!-- ~~~~~ New section ~~~~~ -->
3297 <sect3 renderas="sect4" id="crunch-if-none-match">
3298 <title>crunch-if-none-match</title>
3304 <term>Typical use:</term>
3306 <para>Prevent yet another way to track the user's steps between sessions.</para>
3311 <term>Effect:</term>
3314 Deletes the <quote>If-None-Match:</quote> HTTP client header.
3321 <!-- Boolean, Parameterized, Multi-value -->
3323 <para>Boolean.</para>
3328 <term>Parameter:</term>
3340 Removing the <quote>If-None-Match:</quote> HTTP client header
3341 is useful for filter testing, where you want to force a real
3342 reload instead of getting status code <quote>304</quote> which
3343 would cause the browser to use a cached copy of the page.
3346 It is also useful to make sure the header isn't used as a cookie
3347 replacement (unlikely but possible).
3350 Blocking the <quote>If-None-Match:</quote> header shouldn't cause any
3351 caching problems, as long as the <quote>If-Modified-Since:</quote> header
3352 isn't blocked or missing as well.
3355 It is recommended to use this action together with
3356 <literal><link linkend="hide-if-modified-since">hide-if-modified-since</link></literal>
3358 <literal><link linkend="overwrite-last-modified">overwrite-last-modified</link></literal>.
3364 <term>Example usage (section):</term>
3366 <screen># Let the browser revalidate cached documents but don't
3367 # allow the server to use the revalidation headers for user tracking.
3368 {+hide-if-modified-since{-60} \
3369 +overwrite-last-modified{randomize} \
3370 +crunch-if-none-match}
3379 <!-- ~~~~~ New section ~~~~~ -->
3380 <sect3 renderas="sect4" id="crunch-incoming-cookies">
3381 <title>crunch-incoming-cookies</title>
3385 <term>Typical use:</term>
3388 Prevent the web server from setting HTTP cookies on your system
3394 <term>Effect:</term>
3397 Deletes any <quote>Set-Cookie:</quote> HTTP headers from server replies.
3404 <!-- Boolean, Parameterized, Multi-value -->
3406 <para>Boolean.</para>
3411 <term>Parameter:</term>
3423 This action is only concerned with <emphasis>incoming</emphasis> HTTP cookies. For
3424 <emphasis>outgoing</emphasis> HTTP cookies, use
3425 <literal><link linkend="crunch-outgoing-cookies">crunch-outgoing-cookies</link></literal>.
3426 Use <emphasis>both</emphasis> to disable HTTP cookies completely.
3429 It makes <emphasis>no sense at all</emphasis> to use this action in conjunction
3430 with the <literal><link linkend="session-cookies-only">session-cookies-only</link></literal> action,
3431 since it would prevent the session cookies from being set. See also
3432 <literal><link linkend="filter-content-cookies">filter-content-cookies</link></literal>.
3438 <term>Example usage:</term>
3440 <screen>+crunch-incoming-cookies</screen>
3447 <!-- ~~~~~ New section ~~~~~ -->
3448 <sect3 renderas="sect4" id="crunch-server-header">
3449 <title>crunch-server-header</title>
3455 <term>Typical use:</term>
3457 <para>Remove a server header <application>Privoxy</application> has no dedicated action for.</para>
3462 <term>Effect:</term>
3465 Deletes every header sent by the server that contains the string the user supplied as parameter.
3472 <!-- Boolean, Parameterized, Multi-value -->
3474 <para>Parameterized.</para>
3479 <term>Parameter:</term>
3491 This action allows you to block server headers for which no dedicated
3492 <application>Privoxy</application> action exists. <application>Privoxy</application>
3493 will remove every server header that contains the string you supplied as parameter.
3496 Regular expressions are <emphasis>not supported</emphasis> and you can't
3497 use this action to block different headers in the same request, unless
3498 they contain the same string.
3501 <literal>crunch-server-header</literal> is only meant for quick tests.
3502 If you have to block several different headers, or only want to modify
3503 parts of them, you should use a custom
3504 <literal><link linkend="server-header-filter">server-header filter</link></literal>.
3508 Don't block any header without understanding the consequences.
3515 <term>Example usage (section):</term>
3517 <screen># Crunch server headers that try to prevent caching
3518 { +crunch-server-header{no-cache} }
3527 <!-- ~~~~~ New section ~~~~~ -->
3528 <sect3 renderas="sect4" id="crunch-outgoing-cookies">
3529 <title>crunch-outgoing-cookies</title>
3533 <term>Typical use:</term>
3536 Prevent the web server from reading any HTTP cookies from your system
3542 <term>Effect:</term>
3545 Deletes any <quote>Cookie:</quote> HTTP headers from client requests.
3552 <!-- Boolean, Parameterized, Multi-value -->
3554 <para>Boolean.</para>
3559 <term>Parameter:</term>
3571 This action is only concerned with <emphasis>outgoing</emphasis> HTTP cookies. For
3572 <emphasis>incoming</emphasis> HTTP cookies, use
3573 <literal><link linkend="crunch-incoming-cookies">crunch-incoming-cookies</link></literal>.
3574 Use <emphasis>both</emphasis> to disable HTTP cookies completely.
3577 It makes <emphasis>no sense at all</emphasis> to use this action in conjunction
3578 with the <literal><link linkend="session-cookies-only">session-cookies-only</link></literal> action,
3579 since it would prevent the session cookies from being read.
3585 <term>Example usage:</term>
3587 <screen>+crunch-outgoing-cookies</screen>
3595 <!-- ~~~~~ New section ~~~~~ -->
3596 <sect3 renderas="sect4" id="deanimate-gifs">
3597 <title>deanimate-gifs</title>
3601 <term>Typical use:</term>
3603 <para>Stop those annoying, distracting animated GIF images.</para>
3608 <term>Effect:</term>
3611 De-animate GIF animations, i.e. reduce them to their first or last image.
3618 <!-- boolean, parameterized, Multi-value -->
3620 <para>Parameterized.</para>
3625 <term>Parameter:</term>
3628 <quote>last</quote> or <quote>first</quote>
3637 This will also shrink the images considerably (in bytes, not pixels!). If
3638 the option <quote>first</quote> is given, the first frame of the animation
3639 is used as the replacement. If <quote>last</quote> is given, the last
3640 frame of the animation is used instead, which probably makes more sense for
3641 most banner animations, but also has the risk of not showing the entire
3642 last frame (if it is only a delta to an earlier frame).
3645 You can safely use this action with patterns that will also match non-GIF
3646 objects, because no attempt will be made at anything that doesn't look like
3653 <term>Example usage:</term>
3655 <screen>+deanimate-gifs{last}</screen>
3661 <!-- ~~~~~ New section ~~~~~ -->
3662 <sect3 renderas="sect4" id="downgrade-http-version">
3663 <title>downgrade-http-version</title>
3667 <term>Typical use:</term>
3669 <para>Work around (very rare) problems with HTTP/1.1</para>
3674 <term>Effect:</term>
3677 Downgrades HTTP/1.1 client requests and server replies to HTTP/1.0.
3684 <!-- boolean, parameterized, Multi-value -->
3686 <para>Boolean.</para>
3691 <term>Parameter:</term>
3703 This is a left-over from the time when <application>Privoxy</application>
3704 didn't support important HTTP/1.1 features well. It is left here for the
3705 unlikely case that you experience HTTP/1.1-related problems with some server
3709 Note that enabling this action is only a workaround. It should not
3710 be enabled for sites that work without it. While it shouldn't break
3711 any pages, it has an (usually negative) performance impact.
3714 If you come across a site where enabling this action helps, please report it,
3715 so the cause of the problem can be analyzed. If the problem turns out to be
3716 caused by a bug in <application>Privoxy</application> it should be
3717 fixed so the following release works without the work around.
3723 <term>Example usage (section):</term>
3725 <screen>{+downgrade-http-version}
3726 problem-host.example.com</screen>
3733 <!-- ~~~~~ New section ~~~~~ -->
3734 <sect3 renderas="sect4" id="external-filter">
3735 <title>external-filter</title>
3739 <term>Typical use:</term>
3741 <para>Modify content using a programming language of your choice.</para>
3746 <term>Effect:</term>
3749 All instances of text-based type, most notably HTML and JavaScript, to which
3750 this action applies, can be filtered on-the-fly through the specified external
3752 By default plain text documents are exempted from filtering, because web
3753 servers often use the <literal>text/plain</literal> MIME type for all files
3754 whose type they don't know.)
3761 <!-- boolean, parameterized, Multi-value -->
3763 <para>Multi-value.</para>
3768 <term>Parameter:</term>
3771 The name of an external content filter, as defined in the
3772 <link linkend="filter-file">filter file</link>.
3773 External filters can be defined in one or more files as defined by the
3774 <literal><link linkend="filterfile">filterfile</link></literal>
3775 option in the <link linkend="config">config file</link>.
3778 When used in its negative form,
3779 and without parameters, <emphasis>all</emphasis> filtering with external
3780 filters is completely disabled.
3789 External filters are scripts or programs that can modify the content in
3790 case common <literal><link linkend="filter">filters</link></literal>
3791 aren't powerful enough. With the exception that this action doesn't
3792 use pcrs-based filters, the notes in the
3793 <literal><link linkend="filter">filter</link></literal> section apply.
3797 Currently external filters are executed with &my-app;'s privileges.
3798 Only use external filters you understand and trust.
3802 This feature is experimental, the <literal><link
3803 linkend="external-filter-syntax">syntax</link></literal>
3804 may change in the future.
3811 <term>Example usage:</term>
3813 <screen>+external-filter{fancy-filter}</screen>
3819 <!-- ~~~~~ New section ~~~~~ -->
3820 <sect3 renderas="sect4" id="fast-redirects">
3821 <title>fast-redirects</title>
3825 <term>Typical use:</term>
3827 <para>Fool some click-tracking scripts and speed up indirect links.</para>
3832 <term>Effect:</term>
3835 Detects redirection URLs and redirects the browser without contacting
3836 the redirection server first.
3843 <!-- boolean, parameterized, Multi-value -->
3845 <para>Parameterized.</para>
3850 <term>Parameter:</term>
3855 <quote>simple-check</quote> to just search for the string <quote>http://</quote>
3856 to detect redirection URLs.
3861 <quote>check-decoded-url</quote> to decode URLs (if necessary) before searching
3862 for redirection URLs.
3873 Many sites, like yahoo.com, don't just link to other sites. Instead, they
3874 will link to some script on their own servers, giving the destination as a
3875 parameter, which will then redirect you to the final target. URLs
3876 resulting from this scheme typically look like:
3877 <quote>http://www.example.org/click-tracker.cgi?target=http%3a//www.example.net/</quote>.
3880 Sometimes, there are even multiple consecutive redirects encoded in the
3881 URL. These redirections via scripts make your web browsing more traceable,
3882 since the server from which you follow such a link can see where you go
3883 to. Apart from that, valuable bandwidth and time is wasted, while your
3884 browser asks the server for one redirect after the other. Plus, it feeds
3888 This feature is currently not very smart and is scheduled for improvement.
3889 If it is enabled by default, you will have to create some exceptions to
3890 this action. It can lead to failures in several ways:
3893 Not every URLs with other URLs as parameters is evil.
3894 Some sites offer a real service that requires this information to work.
3895 For example a validation service needs to know, which document to validate.
3896 <literal>fast-redirects</literal> assumes that every URL parameter that
3897 looks like another URL is a redirection target, and will always redirect to
3898 the last one. Most of the time the assumption is correct, but if it isn't,
3899 the user gets redirected anyway.
3902 Another failure occurs if the URL contains other parameters after the URL parameter.
3904 <quote>http://www.example.org/?redirect=http%3a//www.example.net/&foo=bar</quote>.
3905 contains the redirection URL <quote>http://www.example.net/</quote>,
3906 followed by another parameter. <literal>fast-redirects</literal> doesn't know that
3907 and will cause a redirect to <quote>http://www.example.net/&foo=bar</quote>.
3908 Depending on the target server configuration, the parameter will be silently ignored
3909 or lead to a <quote>page not found</quote> error. You can prevent this problem by
3910 first using the <literal><link linkend="redirect">redirect</link></literal> action
3911 to remove the last part of the URL, but it requires a little effort.
3914 To detect a redirection URL, <literal>fast-redirects</literal> only
3915 looks for the string <quote>http://</quote>, either in plain text
3916 (invalid but often used) or encoded as <quote>http%3a//</quote>.
3917 Some sites use their own URL encoding scheme, encrypt the address
3918 of the target server or replace it with a database id. In theses cases
3919 <literal>fast-redirects</literal> is fooled and the request reaches the
3920 redirection server where it probably gets logged.
3926 <term>Example usage:</term>
3929 { +fast-redirects{simple-check} }
3932 { +fast-redirects{check-decoded-url} }
3933 another.example.com/testing</screen>
3941 <!-- ~~~~~ New section ~~~~~ -->
3942 <sect3 renderas="sect4" id="filter">
3943 <title>filter</title>
3947 <term>Typical use:</term>
3949 <para>Get rid of HTML and JavaScript annoyances, banner advertisements (by size),
3950 do fun text replacements, add personalized effects, etc.</para>
3955 <term>Effect:</term>
3958 All instances of text-based type, most notably HTML and JavaScript, to which
3959 this action applies, can be filtered on-the-fly through the specified regular
3960 expression based substitutions. (Note: as of version 3.0.3 plain text documents
3961 are exempted from filtering, because web servers often use the
3962 <literal>text/plain</literal> MIME type for all files whose type they don't know.)
3969 <!-- boolean, parameterized, Multi-value -->
3971 <para>Multi-value.</para>
3976 <term>Parameter:</term>
3979 The name of a content filter, as defined in the <link linkend="filter-file">filter file</link>.
3980 Filters can be defined in one or more files as defined by the
3981 <literal><link linkend="filterfile">filterfile</link></literal>
3982 option in the <link linkend="config">config file</link>.
3983 <filename>default.filter</filename> is the collection of filters
3984 supplied by the developers. Locally defined filters should go
3985 in their own file, such as <filename>user.filter</filename>.
3988 When used in its negative form,
3989 and without parameters, <emphasis>all</emphasis> filtering is completely disabled.
3998 For your convenience, there are a number of pre-defined filters available
3999 in the distribution filter file that you can use. See the examples below for
4003 Filtering requires buffering the page content, which may appear to
4004 slow down page rendering since nothing is displayed until all content has
4005 passed the filters. (The total time until the page is completely rendered
4006 doesn't change much, but it may be perceived as slower since the page is
4007 not incrementally displayed.)
4008 This effect will be more noticeable on slower connections.
4011 <quote>Rolling your own</quote>
4012 filters requires a knowledge of
4013 <ulink url="http://en.wikipedia.org/wiki/Regular_expressions"><quote>Regular
4014 Expressions</quote></ulink> and
4015 <ulink url="http://en.wikipedia.org/wiki/Html"><quote>HTML</quote></ulink>.
4016 This is very powerful feature, and potentially very intrusive.
4017 Filters should be used with caution, and where an equivalent
4018 <quote>action</quote> is not available.
4021 The amount of data that can be filtered is limited to the
4022 <literal><link linkend="buffer-limit">buffer-limit</link></literal>
4023 option in the main <link linkend="config">config file</link>. The
4024 default is 4096 KB (4 Megs). Once this limit is exceeded, the buffered
4025 data, and all pending data, is passed through unfiltered.
4028 Inappropriate MIME types, such as zipped files, are not filtered at all.
4029 (Again, only text-based types except plain text). Encrypted SSL data
4030 (from HTTPS servers) cannot be filtered either, since this would violate
4031 the integrity of the secure transaction. In some situations it might
4032 be necessary to protect certain text, like source code, from filtering
4033 by defining appropriate <literal>-filter</literal> exceptions.
4036 Compressed content can't be filtered either, but if &my-app;
4037 is compiled with zlib support and a supported compression algorithm
4038 is used (gzip or deflate), &my-app; can first decompress the content
4042 If you use a &my-app; version without zlib support, but want filtering to work on
4043 as much documents as possible, even those that would normally be sent compressed,
4044 you must use the <literal><link linkend="prevent-compression">prevent-compression</link></literal>
4045 action in conjunction with <literal>filter</literal>.
4048 Content filtering can achieve some of the same effects as the
4049 <literal><link linkend="block">block</link></literal>
4050 action, i.e. it can be used to block ads and banners. But the mechanism
4051 works quite differently. One effective use, is to block ad banners
4052 based on their size (see below), since many of these seem to be somewhat
4056 <link linkend="contact">Feedback</link> with suggestions for new or
4057 improved filters is particularly welcome!
4060 The below list has only the names and a one-line description of each
4061 predefined filter. There are <link linkend="predefined-filters">more
4062 verbose explanations</link> of what these filters do in the <link
4063 linkend="filter-file">filter file chapter</link>.
4069 <term>Example usage (with filters from the distribution <filename>default.filter</filename> file).
4070 See <link linkend="PREDEFINED-FILTERS">the Predefined Filters section</link> for
4071 more explanation on each:</term>
4074 <anchor id="filter-js-annoyances">
4076 <screen>+filter{js-annoyances} # Get rid of particularly annoying JavaScript abuse.</screen>
4078 <anchor id="filter-js-events">
4080 <screen>+filter{js-events} # Kill JavaScript event bindings and timers (Radically destructive! Only for extra nasty sites).</screen>
4082 <anchor id="filter-html-annoyances">
4084 <screen>+filter{html-annoyances} # Get rid of particularly annoying HTML abuse.</screen>
4086 <anchor id="filter-content-cookies">
4088 <screen>+filter{content-cookies} # Kill cookies that come in the HTML or JS content.</screen>
4090 <anchor id="filter-refresh-tags">
4092 <screen>+filter{refresh-tags} # Kill automatic refresh tags if refresh time is larger than 9 seconds.</screen>
4094 <anchor id="filter-unsolicited-popups">
4096 <screen>+filter{unsolicited-popups} # Disable only unsolicited pop-up windows.</screen>
4098 <anchor id="filter-all-popups">
4100 <screen>+filter{all-popups} # Kill all popups in JavaScript and HTML.</screen>
4102 <anchor id="filter-img-reorder">
4104 <screen>+filter{img-reorder} # Reorder attributes in <img> tags to make the banners-by-* filters more effective.</screen>
4106 <anchor id="filter-banners-by-size">
4108 <screen>+filter{banners-by-size} # Kill banners by size.</screen>
4110 <anchor id="filter-banners-by-link">
4112 <screen>+filter{banners-by-link} # Kill banners by their links to known clicktrackers.</screen>
4114 <anchor id="filter-webbugs">
4116 <screen>+filter{webbugs} # Squish WebBugs (1x1 invisible GIFs used for user tracking).</screen>
4118 <anchor id="filter-tiny-textforms">
4120 <screen>+filter{tiny-textforms} # Extend those tiny textareas up to 40x80 and kill the hard wrap.</screen>
4122 <anchor id="filter-jumping-windows">
4124 <screen>+filter{jumping-windows} # Prevent windows from resizing and moving themselves.</screen>
4126 <anchor id="filter-frameset-borders">
4128 <screen>+filter{frameset-borders} # Give frames a border and make them resizable.</screen>
4130 <anchor id="filter-iframes">
4132 <screen>+filter{iframes} # Removes all detected iframes. Should only be enabled for individual sites.</screen>
4134 <anchor id="filter-demoronizer">
4136 <screen>+filter{demoronizer} # Fix MS's non-standard use of standard charsets.</screen>
4138 <anchor id="filter-shockwave-flash">
4140 <screen>+filter{shockwave-flash} # Kill embedded Shockwave Flash objects.</screen>
4142 <anchor id="filter-quicktime-kioskmode">
4144 <screen>+filter{quicktime-kioskmode} # Make Quicktime movies saveable.</screen>
4146 <anchor id="filter-fun">
4148 <screen>+filter{fun} # Text replacements for subversive browsing fun!</screen>
4150 <anchor id="filter-crude-parental">
4152 <screen>+filter{crude-parental} # Crude parental filtering. Note that this filter doesn't work reliably.</screen>
4154 <anchor id="filter-ie-exploits">
4156 <screen>+filter{ie-exploits} # Disable some known Internet Explorer bug exploits.</screen>
4158 <anchor id="filter-site-specifics">
4160 <screen>+filter{site-specifics} # Cure for site-specific problems. Don't apply generally!</screen>
4162 <anchor id="filter-no-ping">
4164 <screen>+filter{no-ping} # Removes non-standard ping attributes in <a> and <area> tags.</screen>
4166 <anchor id="filter-google">
4168 <screen>+filter{google} # CSS-based block for Google text ads. Also removes a width limitation and the toolbar advertisement.</screen>
4170 <anchor id="filter-yahoo">
4172 <screen>+filter{yahoo} # CSS-based block for Yahoo text ads. Also removes a width limitation.</screen>
4174 <anchor id="filter-msn">
4176 <screen>+filter{msn} # CSS-based block for MSN text ads. Also removes tracking URLs and a width limitation.</screen>
4178 <anchor id="filter-blogspot">
4180 <screen>+filter{blogspot} # Cleans up some Blogspot blogs. Read the fine print before using this.</screen>
4187 <!-- ~~~~~ New section ~~~~~ -->
4188 <sect3 renderas="sect4" id="force-text-mode">
4189 <title>force-text-mode</title>
4195 <term>Typical use:</term>
4197 <para>Force <application>Privoxy</application> to treat a document as if it was in some kind of <emphasis>text</emphasis> format. </para>
4202 <term>Effect:</term>
4205 Declares a document as text, even if the <quote>Content-Type:</quote> isn't detected as such.
4212 <!-- Boolean, Parameterized, Multi-value -->
4214 <para>Boolean.</para>
4219 <term>Parameter:</term>
4231 As explained <literal><link linkend="filter">above</link></literal>,
4232 <application>Privoxy</application> tries to only filter files that are
4233 in some kind of text format. The same restrictions apply to
4234 <literal><link linkend="content-type-overwrite">content-type-overwrite</link></literal>.
4235 <literal>force-text-mode</literal> declares a document as text,
4236 without looking at the <quote>Content-Type:</quote> first.
4240 Think twice before activating this action. Filtering binary data
4241 with regular expressions can cause file damage.
4248 <term>Example usage:</term>
4259 <!-- ~~~~~ New section ~~~~~ -->
4260 <sect3 renderas="sect4" id="forward-override">
4261 <title>forward-override</title>
4267 <term>Typical use:</term>
4269 <para>Change the forwarding settings based on User-Agent or request origin</para>
4274 <term>Effect:</term>
4277 Overrules the forward directives in the configuration file.
4284 <!-- Boolean, Parameterized, Multi-value -->
4286 <para>Parameterized.</para>
4291 <term>Parameter:</term>
4295 <para><quote>forward .</quote> to use a direct connection without any additional proxies.</para>
4299 <quote>forward 127.0.0.1:8123</quote> to use the HTTP proxy listening at 127.0.0.1 port 8123.
4304 <quote>forward-socks4a 127.0.0.1:9050 .</quote> to use the socks4a proxy listening at
4305 127.0.0.1 port 9050. Replace <quote>forward-socks4a</quote> with <quote>forward-socks4</quote>
4306 to use a socks4 connection (with local DNS resolution) instead, use <quote>forward-socks5</quote>
4307 for socks5 connections (with remote DNS resolution).
4312 <quote>forward-socks4a 127.0.0.1:9050 proxy.example.org:8000</quote> to use the socks4a proxy
4313 listening at 127.0.0.1 port 9050 to reach the HTTP proxy listening at proxy.example.org port 8000.
4314 Replace <quote>forward-socks4a</quote> with <quote>forward-socks4</quote> to use a socks4 connection
4315 (with local DNS resolution) instead, use <quote>forward-socks5</quote>
4316 for socks5 connections (with remote DNS resolution).
4321 <quote>forward-webserver 127.0.0.1:80</quote> to use the HTTP
4322 server listening at 127.0.0.1 port 80 without adjusting the
4326 This makes it more convenient to use Privoxy to make
4327 existing websites available as onion services as well.
4330 Many websites serve content with hardcoded URLs and
4331 can't be easily adjusted to change the domain based
4332 on the one used by the client.
4335 Putting Privoxy between Tor and the webserver (or an stunnel
4336 that forwards to the webserver) allows to rewrite headers and
4337 content to make client and server happy at the same time.
4340 Using Privoxy for webservers that are only reachable through
4341 onion addresses and whose location is supposed to be secret
4342 is not recommended and should not be necessary anyway.
4353 This action takes parameters similar to the
4354 <link linkend="forwarding">forward</link> directives in the configuration
4355 file, but without the URL pattern. It can be used as replacement, but normally it's only
4356 used in cases where matching based on the request URL isn't sufficient.
4360 Please read the description for the <link linkend="forwarding">forward</link> directives before
4361 using this action. Forwarding to the wrong people will reduce your privacy and increase the
4362 chances of man-in-the-middle attacks.
4365 If the ports are missing or invalid, default values will be used. This might change
4366 in the future and you shouldn't rely on it. Otherwise incorrect syntax causes Privoxy
4367 to exit. Due to design limitations, invalid parameter syntax isn't detected until the
4368 action is used the first time.
4371 Use the <ulink url="http://config.privoxy.org/show-url-info">show-url-info CGI page</ulink>
4372 to verify that your forward settings do what you thought the do.
4379 <term>Example usage:</term>
4382 # Use an ssh tunnel for requests previously tagged as
4383 # <quote>User-Agent: fetch libfetch/2.0</quote> and make sure
4384 # resuming downloads continues to work.
4386 # This way you can continue to use Tor for your normal browsing,
4387 # without overloading the Tor network with your FreeBSD ports updates
4388 # or downloads of bigger files like ISOs.
4390 # Note that HTTP headers are easy to fake and therefore their
4391 # values are as (un)trustworthy as your clients and users.
4392 {+forward-override{forward-socks5 10.0.0.2:2222 .} \
4393 -hide-if-modified-since \
4394 -overwrite-last-modified \
4396 TAG:^User-Agent: fetch libfetch/2\.0$
4404 <!-- ~~~~~ New section ~~~~~ -->
4405 <sect3 renderas="sect4" id="handle-as-empty-document">
4406 <title>handle-as-empty-document</title>
4412 <term>Typical use:</term>
4414 <para>Mark URLs that should be replaced by empty documents <emphasis>if they get blocked</emphasis></para>
4419 <term>Effect:</term>
4422 This action alone doesn't do anything noticeable. It just marks URLs.
4423 If the <literal><link linkend="block">block</link></literal> action <emphasis>also applies</emphasis>,
4424 the presence or absence of this mark decides whether an HTML <quote>BLOCKED</quote>
4425 page, or an empty document will be sent to the client as a substitute for the blocked content.
4426 The <emphasis>empty</emphasis> document isn't literally empty, but actually contains a single space.
4433 <!-- Boolean, Parameterized, Multi-value -->
4435 <para>Boolean.</para>
4440 <term>Parameter:</term>
4452 Some browsers complain about syntax errors if JavaScript documents
4453 are blocked with <application>Privoxy's</application>
4454 default HTML page; this option can be used to silence them.
4455 And of course this action can also be used to eliminate the &my-app;
4456 BLOCKED message in frames.
4459 The content type for the empty document can be specified with
4460 <literal><link linkend="content-type-overwrite">content-type-overwrite{}</link></literal>,
4461 but usually this isn't necessary.
4467 <term>Example usage:</term>
4469 <screen># Block all documents on example.org that end with ".js",
4470 # but send an empty document instead of the usual HTML message.
4471 {+block{Blocked JavaScript} +handle-as-empty-document}
4480 <!-- ~~~~~ New section ~~~~~ -->
4481 <sect3 renderas="sect4" id="handle-as-image">
4482 <title>handle-as-image</title>
4486 <term>Typical use:</term>
4488 <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>
4493 <term>Effect:</term>
4496 This action alone doesn't do anything noticeable. It just marks URLs as images.
4497 If the <literal><link linkend="block">block</link></literal> action <emphasis>also applies</emphasis>,
4498 the presence or absence of this mark decides whether an HTML <quote>blocked</quote>
4499 page, or a replacement image (as determined by the <literal><link
4500 linkend="set-image-blocker">set-image-blocker</link></literal> action) will be sent to the
4501 client as a substitute for the blocked content.
4508 <!-- Boolean, Parameterized, Multi-value -->
4510 <para>Boolean.</para>
4515 <term>Parameter:</term>
4527 The below generic example section is actually part of <filename>default.action</filename>.
4528 It marks all URLs with well-known image file name extensions as images and should
4532 Users will probably only want to use the handle-as-image action in conjunction with
4533 <literal><link linkend="block">block</link></literal>, to block sources of banners, whose URLs don't
4534 reflect the file type, like in the second example section.
4537 Note that you cannot treat HTML pages as images in most cases. For instance, (in-line) ad
4538 frames require an HTML page to be sent, or they won't display properly.
4539 Forcing <literal>handle-as-image</literal> in this situation will not replace the
4540 ad frame with an image, but lead to error messages.
4546 <term>Example usage (sections):</term>
4548 <screen># Generic image extensions:
4551 /.*\.(gif|jpg|jpeg|png|bmp|ico)$
4553 # These don't look like images, but they're banners and should be
4554 # blocked as images:
4556 {+block{Nasty banners.} +handle-as-image}
4557 nasty-banner-server.example.com/junk.cgi\?output=trash
4565 <!-- ~~~~~ New section ~~~~~ -->
4566 <sect3 renderas="sect4" id="hide-accept-language">
4567 <title>hide-accept-language</title>
4573 <term>Typical use:</term>
4575 <para>Pretend to use different language settings.</para>
4580 <term>Effect:</term>
4583 Deletes or replaces the <quote>Accept-Language:</quote> HTTP header in client requests.
4590 <!-- Boolean, Parameterized, Multi-value -->
4592 <para>Parameterized.</para>
4597 <term>Parameter:</term>
4600 Keyword: <quote>block</quote>, or any user defined value.
4609 Faking the browser's language settings can be useful to make a
4610 foreign User-Agent set with
4611 <literal><link linkend="hide-user-agent">hide-user-agent</link></literal>
4615 However some sites with content in different languages check the
4616 <quote>Accept-Language:</quote> to decide which one to take by default.
4617 Sometimes it isn't possible to later switch to another language without
4618 changing the <quote>Accept-Language:</quote> header first.
4621 Therefore it's a good idea to either only change the
4622 <quote>Accept-Language:</quote> header to languages you understand,
4623 or to languages that aren't wide spread.
4626 Before setting the <quote>Accept-Language:</quote> header
4627 to a rare language, you should consider that it helps to
4628 make your requests unique and thus easier to trace.
4629 If you don't plan to change this header frequently,
4630 you should stick to a common language.
4636 <term>Example usage (section):</term>
4638 <screen># Pretend to use Canadian language settings.
4639 {+hide-accept-language{en-ca} \
4640 +hide-user-agent{Mozilla/5.0 (X11; U; OpenBSD i386; en-CA; rv:1.8.0.4) Gecko/20060628 Firefox/1.5.0.4} \
4650 <!-- ~~~~~ New section ~~~~~ -->
4651 <sect3 renderas="sect4" id="hide-content-disposition">
4652 <title>hide-content-disposition</title>
4658 <term>Typical use:</term>
4660 <para>Prevent download menus for content you prefer to view inside the browser.</para>
4665 <term>Effect:</term>
4668 Deletes or replaces the <quote>Content-Disposition:</quote> HTTP header set by some servers.
4675 <!-- Boolean, Parameterized, Multi-value -->
4677 <para>Parameterized.</para>
4682 <term>Parameter:</term>
4685 Keyword: <quote>block</quote>, or any user defined value.
4694 Some servers set the <quote>Content-Disposition:</quote> HTTP header for
4695 documents they assume you want to save locally before viewing them.
4696 The <quote>Content-Disposition:</quote> header contains the file name
4697 the browser is supposed to use by default.
4700 In most browsers that understand this header, it makes it impossible to
4701 <emphasis>just view</emphasis> the document, without downloading it first,
4702 even if it's just a simple text file or an image.
4705 Removing the <quote>Content-Disposition:</quote> header helps
4706 to prevent this annoyance, but some browsers additionally check the
4707 <quote>Content-Type:</quote> header, before they decide if they can
4708 display a document without saving it first. In these cases, you have
4709 to change this header as well, before the browser stops displaying
4713 It is also possible to change the server's file name suggestion
4714 to another one, but in most cases it isn't worth the time to set
4718 This action will probably be removed in the future,
4719 use server-header filters instead.
4725 <term>Example usage:</term>
4727 <screen># Disarm the download link in Sourceforge's patch tracker
4729 +content-type-overwrite{text/plain}\
4730 +hide-content-disposition{block} }
4731 .sourceforge.net/tracker/download\.php</screen>
4738 <!-- ~~~~~ New section ~~~~~ -->
4739 <sect3 renderas="sect4" id="hide-if-modified-since">
4740 <title>hide-if-modified-since</title>
4746 <term>Typical use:</term>
4748 <para>Prevent yet another way to track the user's steps between sessions.</para>
4753 <term>Effect:</term>
4756 Deletes the <quote>If-Modified-Since:</quote> HTTP client header or modifies its value.
4763 <!-- Boolean, Parameterized, Multi-value -->
4765 <para>Parameterized.</para>
4770 <term>Parameter:</term>
4773 Keyword: <quote>block</quote>, or a user defined value that specifies a range of hours.
4782 Removing this header is useful for filter testing, where you want to force a real
4783 reload instead of getting status code <quote>304</quote>, which would cause the
4784 browser to use a cached copy of the page.
4787 Instead of removing the header, <literal>hide-if-modified-since</literal> can
4788 also add or subtract a random amount of time to/from the header's value.
4789 You specify a range of minutes where the random factor should be chosen from and
4790 <application>Privoxy</application> does the rest. A negative value means
4791 subtracting, a positive value adding.
4794 Randomizing the value of the <quote>If-Modified-Since:</quote> makes
4795 it less likely that the server can use the time as a cookie replacement,
4796 but you will run into caching problems if the random range is too high.
4799 It is a good idea to only use a small negative value and let
4800 <literal><link linkend="overwrite-last-modified">overwrite-last-modified</link></literal>
4801 handle the greater changes.
4804 It is also recommended to use this action together with
4805 <literal><link linkend="crunch-if-none-match">crunch-if-none-match</link></literal>,
4806 otherwise it's more or less pointless.
4812 <term>Example usage (section):</term>
4814 <screen># Let the browser revalidate but make tracking based on the time less likely.
4815 {+hide-if-modified-since{-60} \
4816 +overwrite-last-modified{randomize} \
4817 +crunch-if-none-match}
4825 <!-- ~~~~~ New section ~~~~~ -->
4826 <sect3 renderas="sect4" id="hide-from-header">
4827 <title>hide-from-header</title>
4831 <term>Typical use:</term>
4833 <para>Keep your (old and ill) browser from telling web servers your email address</para>
4838 <term>Effect:</term>
4841 Deletes any existing <quote>From:</quote> HTTP header, or replaces it with the
4849 <!-- Boolean, Parameterized, Multi-value -->
4851 <para>Parameterized.</para>
4856 <term>Parameter:</term>
4859 Keyword: <quote>block</quote>, or any user defined value.
4868 The keyword <quote>block</quote> will completely remove the header
4869 (not to be confused with the <literal><link linkend="block">block</link></literal>
4873 Alternately, you can specify any value you prefer to be sent to the web
4874 server. If you do, it is a matter of fairness not to use any address that
4875 is actually used by a real person.
4878 This action is rarely needed, as modern web browsers don't send
4879 <quote>From:</quote> headers anymore.
4885 <term>Example usage:</term>
4887 <screen>+hide-from-header{block}</screen>
4889 <screen>+hide-from-header{spam-me-senseless@sittingduck.example.com}</screen>
4896 <!-- ~~~~~ New section ~~~~~ -->
4897 <sect3 renderas="sect4" id="hide-referrer">
4898 <title>hide-referrer</title>
4899 <anchor id="hide-referer">
4902 <term>Typical use:</term>
4904 <para>Conceal which link you followed to get to a particular site</para>
4909 <term>Effect:</term>
4912 Deletes the <quote>Referer:</quote> (sic) HTTP header from the client request,
4913 or replaces it with a forged one.
4920 <!-- Boolean, Parameterized, Multi-value -->
4922 <para>Parameterized.</para>
4927 <term>Parameter:</term>
4931 <para><quote>conditional-block</quote> to delete the header completely if the host has changed.</para>
4934 <para><quote>conditional-forge</quote> to forge the header if the host has changed.</para>
4937 <para><quote>block</quote> to delete the header unconditionally.</para>
4940 <para><quote>forge</quote> to pretend to be coming from the homepage of the server we are talking to.</para>
4943 <para>Any other string to set a user defined referrer.</para>
4953 <literal>conditional-block</literal> is the only parameter,
4954 that isn't easily detected in the server's log file. If it blocks the
4955 referrer, the request will look like the visitor used a bookmark or
4956 typed in the address directly.
4959 Leaving the referrer unmodified for requests on the same host
4960 allows the server owner to see the visitor's <quote>click path</quote>,
4961 but in most cases she could also get that information by comparing
4962 other parts of the log file: for example the User-Agent if it isn't
4963 a very common one, or the user's IP address if it doesn't change between
4967 Always blocking the referrer, or using a custom one, can lead to
4968 failures on servers that check the referrer before they answer any
4969 requests, in an attempt to prevent their content from being
4970 embedded or linked to elsewhere.
4973 Both <literal>conditional-block</literal> and <literal>forge</literal>
4974 will work with referrer checks, as long as content and valid referring page
4975 are on the same host. Most of the time that's the case.
4978 <literal>hide-referer</literal> is an alternate spelling of
4979 <literal>hide-referrer</literal> and the two can be can be freely
4980 substituted with each other. (<quote>referrer</quote> is the
4981 correct English spelling, however the HTTP specification has a bug - it
4982 requires it to be spelled as <quote>referer</quote>.)
4988 <term>Example usage:</term>
4990 <screen>+hide-referrer{forge}</screen>
4992 <screen>+hide-referrer{http://www.yahoo.com/}</screen>
4999 <!-- ~~~~~ New section ~~~~~ -->
5000 <sect3 renderas="sect4" id="hide-user-agent">
5001 <title>hide-user-agent</title>
5005 <term>Typical use:</term>
5007 <para>Try to conceal your type of browser and client operating system</para>
5012 <term>Effect:</term>
5015 Replaces the value of the <quote>User-Agent:</quote> HTTP header
5016 in client requests with the specified value.
5023 <!-- Boolean, Parameterized, Multi-value -->
5025 <para>Parameterized.</para>
5030 <term>Parameter:</term>
5033 Any user-defined string.
5043 This can lead to problems on web sites that depend on looking at this header in
5044 order to customize their content for different browsers (which, by the
5045 way, is <emphasis>NOT</emphasis> the right thing to do: good web sites
5046 work browser-independently).
5050 Using this action in multi-user setups or wherever different types of
5051 browsers will access the same <application>Privoxy</application> is
5052 <emphasis>not recommended</emphasis>. In single-user, single-browser
5053 setups, you might use it to delete your OS version information from
5054 the headers, because it is an invitation to exploit known bugs for your
5055 OS. It is also occasionally useful to forge this in order to access
5056 sites that won't let you in otherwise (though there may be a good
5057 reason in some cases).
5060 More information on known user-agent strings can be found at
5061 <ulink url="http://www.user-agents.org/">http://www.user-agents.org/</ulink>
5063 <ulink url="http://en.wikipedia.org/wiki/User_agent">http://en.wikipedia.org/wiki/User_agent</ulink>.
5069 <term>Example usage:</term>
5071 <screen>+hide-user-agent{Netscape 6.1 (X11; I; Linux 2.4.18 i686)}</screen>
5078 <!-- ~~~~~ New section ~~~~~ -->
5079 <sect3 renderas="sect4" id="limit-connect">
5080 <title>limit-connect</title>
5084 <term>Typical use:</term>
5086 <para>Prevent abuse of <application>Privoxy</application> as a TCP proxy relay or disable SSL for untrusted sites</para>
5091 <term>Effect:</term>
5094 Specifies to which ports HTTP CONNECT requests are allowable.
5101 <!-- Boolean, Parameterized, Multi-value -->
5103 <para>Parameterized.</para>
5108 <term>Parameter:</term>
5111 A comma-separated list of ports or port ranges (the latter using dashes, with the minimum
5112 defaulting to 0 and the maximum to 65K).
5121 By default, i.e. if no <literal>limit-connect</literal> action applies,
5122 <application>Privoxy</application> allows HTTP CONNECT requests to all
5123 ports. Use <literal>limit-connect</literal> if fine-grained control
5124 is desired for some or all destinations.
5127 The CONNECT methods exists in HTTP to allow access to secure websites
5128 (<quote>https://</quote> URLs) through proxies. It works very simply:
5129 the proxy connects to the server on the specified port, and then
5130 short-circuits its connections to the client and to the remote server.
5131 This means CONNECT-enabled proxies can be used as TCP relays very easily.
5134 <application>Privoxy</application> relays HTTPS traffic without seeing
5135 the decoded content. Websites can leverage this limitation to circumvent &my-app;'s
5136 filters. By specifying an invalid port range you can disable HTTPS entirely.
5142 <term>Example usages:</term>
5144 <!-- I had trouble getting the spacing to look right in my browser -->
5145 <!-- I probably have the wrong font setup, bollocks. -->
5146 <!-- Apparently the emphasis tag uses a proportional font no matter what -->
5147 <screen>+limit-connect{443} # Port 443 is OK.
5148 +limit-connect{80,443} # Ports 80 and 443 are OK.
5149 +limit-connect{-3, 7, 20-100, 500-} # Ports less than 3, 7, 20 to 100 and above 500 are OK.
5150 +limit-connect{-} # All ports are OK
5151 +limit-connect{,} # No HTTPS/SSL traffic is allowed</screen>
5158 <!-- ~~~~~ New section ~~~~~ -->
5159 <sect3 renderas="sect4" id="limit-cookie-lifetime">
5160 <title>limit-cookie-lifetime</title>
5164 <term>Typical use:</term>
5166 <para>Limit the lifetime of HTTP cookies to a couple of minutes or hours.</para>
5171 <term>Effect:</term>
5174 Overwrites the expires field in Set-Cookie server headers if it's above the specified limit.
5181 <!-- Boolean, Parameterized, Multi-value -->
5183 <para>Parameterized.</para>
5188 <term>Parameter:</term>
5191 The lifetime limit in minutes, or 0.
5200 This action reduces the lifetime of HTTP cookies coming from the
5201 server to the specified number of minutes, starting from the time
5202 the cookie passes Privoxy.
5205 Cookies with a lifetime below the limit are not modified.
5206 The lifetime of session cookies is set to the specified limit.
5209 The effect of this action depends on the server.
5212 In case of servers which refresh their cookies with each response
5213 (or at least frequently), the lifetime limit set by this action
5215 Thus, a session associated with the cookie continues to work with
5216 this action enabled, as long as a new request is made before the
5217 last limit set is reached.
5220 However, some servers send their cookies once, with a lifetime of several
5221 years (the year 2037 is a popular choice), and do not refresh them
5222 until a certain event in the future, for example the user logging out.
5223 In this case this action may limit the absolute lifetime of the session,
5224 even if requests are made frequently.
5227 If the parameter is <quote>0</quote>, this action behaves like
5228 <literal><link linkend="session-cookies-only">session-cookies-only</link></literal>.
5234 <term>Example usages:</term>
5236 <screen>+limit-cookie-lifetime{60}</screen>
5242 <!-- ~~~~~ New section ~~~~~ -->
5243 <sect3 renderas="sect4" id="prevent-compression">
5244 <title>prevent-compression</title>
5248 <term>Typical use:</term>
5251 Ensure that servers send the content uncompressed, so it can be
5252 passed through <literal><link linkend="filter">filter</link></literal>s.
5258 <term>Effect:</term>
5261 Removes the Accept-Encoding header which can be used to ask for compressed transfer.
5268 <!-- Boolean, Parameterized, Multi-value -->
5270 <para>Boolean.</para>
5275 <term>Parameter:</term>
5287 More and more websites send their content compressed by default, which
5288 is generally a good idea and saves bandwidth. But the <literal><link
5289 linkend="filter">filter</link></literal> and
5290 <literal><link linkend="deanimate-gifs">deanimate-gifs</link></literal>
5291 actions need access to the uncompressed data.
5294 When compiled with zlib support (available since &my-app; 3.0.7), content that should be
5295 filtered is decompressed on-the-fly and you don't have to worry about this action.
5296 If you are using an older &my-app; version, or one that hasn't been compiled with zlib
5297 support, this action can be used to convince the server to send the content uncompressed.
5300 Most text-based instances compress very well, the size is seldom decreased by less than 50%,
5301 for markup-heavy instances like news feeds saving more than 90% of the original size isn't
5305 Not using compression will therefore slow down the transfer, and you should only
5306 enable this action if you really need it. As of &my-app; 3.0.7 it's disabled in all
5307 predefined action settings.
5310 Note that some (rare) ill-configured sites don't handle requests for uncompressed
5311 documents correctly. Broken PHP applications tend to send an empty document body,
5312 some IIS versions only send the beginning of the content. If you enable
5313 <literal>prevent-compression</literal> per default, you might want to add
5314 exceptions for those sites. See the example for how to do that.
5320 <term>Example usage (sections):</term>
5323 # Selectively turn off compression, and enable a filter
5325 { +filter{tiny-textforms} +prevent-compression }
5326 # Match only these sites
5331 # Or instead, we could set a universal default:
5333 { +prevent-compression }
5336 # Then maybe make exceptions for broken sites:
5338 { -prevent-compression }
5339 .compusa.com/</screen>
5347 <!-- ~~~~~ New section ~~~~~ -->
5348 <sect3 renderas="sect4" id="overwrite-last-modified">
5349 <title>overwrite-last-modified</title>
5355 <term>Typical use:</term>
5357 <para>Prevent yet another way to track the user's steps between sessions.</para>
5362 <term>Effect:</term>
5365 Deletes the <quote>Last-Modified:</quote> HTTP server header or modifies its value.
5372 <!-- Boolean, Parameterized, Multi-value -->
5374 <para>Parameterized.</para>
5379 <term>Parameter:</term>
5382 One of the keywords: <quote>block</quote>, <quote>reset-to-request-time</quote>
5383 and <quote>randomize</quote>
5392 Removing the <quote>Last-Modified:</quote> header is useful for filter
5393 testing, where you want to force a real reload instead of getting status
5394 code <quote>304</quote>, which would cause the browser to reuse the old
5395 version of the page.
5398 The <quote>randomize</quote> option overwrites the value of the
5399 <quote>Last-Modified:</quote> header with a randomly chosen time
5400 between the original value and the current time. In theory the server
5401 could send each document with a different <quote>Last-Modified:</quote>
5402 header to track visits without using cookies. <quote>Randomize</quote>
5403 makes it impossible and the browser can still revalidate cached documents.
5406 <quote>reset-to-request-time</quote> overwrites the value of the
5407 <quote>Last-Modified:</quote> header with the current time. You could use
5408 this option together with
5409 <literal><link linkend="hide-if-modified-since">hide-if-modified-since</link></literal>
5410 to further customize your random range.
5413 The preferred parameter here is <quote>randomize</quote>. It is safe
5414 to use, as long as the time settings are more or less correct.
5415 If the server sets the <quote>Last-Modified:</quote> header to the time
5416 of the request, the random range becomes zero and the value stays the same.
5417 Therefore you should later randomize it a second time with
5418 <literal><link linkend="hide-if-modified-since">hided-if-modified-since</link></literal>,
5422 It is also recommended to use this action together with
5423 <literal><link linkend="crunch-if-none-match">crunch-if-none-match</link></literal>.
5429 <term>Example usage:</term>
5431 <screen># Let the browser revalidate without being tracked across sessions
5432 { +hide-if-modified-since{-60} \
5433 +overwrite-last-modified{randomize} \
5434 +crunch-if-none-match}
5442 <!-- ~~~~~ New section ~~~~~ -->
5443 <sect3 renderas="sect4" id="redirect">
5444 <title>redirect</title>
5450 <term>Typical use:</term>
5453 Redirect requests to other sites.
5459 <term>Effect:</term>
5462 Convinces the browser that the requested document has been moved
5463 to another location and the browser should get it from there.
5470 <!-- Boolean, Parameterized, Multi-value -->
5472 <para>Parameterized</para>
5477 <term>Parameter:</term>
5480 An absolute URL or a single pcrs command.
5489 Requests to which this action applies are answered with a
5490 HTTP redirect to URLs of your choosing. The new URL is
5491 either provided as parameter, or derived by applying a
5492 single pcrs command to the original URL.
5495 The syntax for pcrs commands is documented in the
5496 <link linkend="filter-file">filter file</link> section.
5499 Requests can't be blocked and redirected at the same time,
5500 applying this action together with
5501 <literal><link linkend="block">block</link></literal>
5502 is a configuration error. Currently the request is blocked
5503 and an error message logged, the behavior may change in the
5504 future and result in Privoxy rejecting the action file.
5507 This action can be combined with
5508 <literal><link linkend="fast-redirects">fast-redirects{check-decoded-url}</link></literal>
5509 to redirect to a decoded version of a rewritten URL.
5512 Use this action carefully, make sure not to create redirection loops
5513 and be aware that using your own redirects might make it
5514 possible to fingerprint your requests.
5517 In case of problems with your redirects, or simply to watch
5518 them working, enable <link linkend="DEBUG">debug 128</link>.
5524 <term>Example usages:</term>
5526 <screen># Replace example.com's style sheet with another one
5527 { +redirect{http://localhost/css-replacements/example.com.css} }
5528 example.com/stylesheet\.css
5530 # Create a short, easy to remember nickname for a favorite site
5531 # (relies on the browser to accept and forward invalid URLs to &my-app;)
5532 { +redirect{https://www.privoxy.org/user-manual/actions-file.html} }
5535 # Always use the expanded view for Undeadly.org articles
5536 # (Note the $ at the end of the URL pattern to make sure
5537 # the request for the rewritten URL isn't redirected as well)
5538 {+redirect{s@$@&mode=expanded@}}
5539 undeadly.org/cgi\?action=article&sid=\d*$
5541 # Redirect Google search requests to MSN
5542 {+redirect{s@^http://[^/]*/search\?q=([^&]*).*@http://search.msn.com/results.aspx?q=$1@}}
5545 # Redirect MSN search requests to Yahoo
5546 {+redirect{s@^http://[^/]*/results\.aspx\?q=([^&]*).*@http://search.yahoo.com/search?p=$1@}}
5547 search.msn.com//results\.aspx\?q=
5549 # Redirect http://example.com/&bla=fasel&toChange=foo (and any other value but "bar")
5550 # to http://example.com/&bla=fasel&toChange=bar
5552 # The URL pattern makes sure that the following request isn't redirected again.
5553 {+redirect{s@toChange=[^&]+@toChange=bar@}}
5554 example.com/.*toChange=(?!bar)
5556 # Add a shortcut to look up illumos bugs
5557 {+redirect{s@^http://i([0-9]+)/.*@https://www.illumos.org/issues/$1@}}
5558 # Redirected URL = http://i4974/
5559 # Redirect Destination = https://www.illumos.org/issues/4974
5560 i[0-9][0-9][0-9][0-9]*/
5562 # Redirect remote requests for this manual
5563 # to the local version delivered by Privoxy
5564 {+redirect{s@^http://www@http://config@}}
5565 www.privoxy.org/user-manual/</screen>
5573 <!-- ~~~~~ New section ~~~~~ -->
5574 <sect3 renderas="sect4" id="server-header-filter">
5575 <title>server-header-filter</title>
5579 <term>Typical use:</term>
5582 Rewrite or remove single server headers.
5588 <term>Effect:</term>
5591 All server headers to which this action applies are filtered on-the-fly
5592 through the specified regular expression based substitutions.
5599 <!-- boolean, parameterized, Multi-value -->
5601 <para>Multi-value.</para>
5606 <term>Parameter:</term>
5609 The name of a server-header filter, as defined in one of the
5610 <link linkend="filter-file">filter files</link>.
5619 Server-header filters are applied to each header on its own, not to
5620 all at once. This makes it easier to diagnose problems, but on the downside
5621 you can't write filters that only change header x if header y's value is z.
5622 You can do that by using tags though.
5625 Server-header filters are executed after the other header actions have finished
5626 and use their output as input.
5629 Please refer to the <link linkend="filter-file">filter file chapter</link>
5630 to learn which server-header filters are available by default, and how to
5637 <term>Example usage (section):</term>
5640 {+server-header-filter{html-to-xml}}
5641 example.org/xml-instance-that-is-delivered-as-html
5643 {+server-header-filter{xml-to-html}}
5644 example.org/instance-that-is-delivered-as-xml-but-is-not
5653 <!-- ~~~~~ New section ~~~~~ -->
5654 <sect3 renderas="sect4" id="server-header-tagger">
5655 <title>server-header-tagger</title>
5659 <term>Typical use:</term>
5662 Enable or disable filters based on the Content-Type header.
5668 <term>Effect:</term>
5671 Server headers to which this action applies are filtered on-the-fly through
5672 the specified regular expression based substitutions, the result is used as
5680 <!-- boolean, parameterized, Multi-value -->
5682 <para>Multi-value.</para>
5687 <term>Parameter:</term>
5690 The name of a server-header tagger, as defined in one of the
5691 <link linkend="filter-file">filter files</link>.
5700 Server-header taggers are applied to each header on its own,
5701 and as the header isn't modified, each tagger <quote>sees</quote>
5705 Server-header taggers are executed before all other header actions
5706 that modify server headers. Their tags can be used to control
5707 all of the other server-header actions, the content filters
5708 and the crunch actions (<link linkend="redirect">redirect</link>
5709 and <link linkend="block">block</link>).
5712 Obviously crunching based on tags created by server-header taggers
5713 doesn't prevent the request from showing up in the server's log file.
5720 <term>Example usage (section):</term>
5723 # Tag every request with the content type declared by the server
5724 {+server-header-tagger{content-type}}
5727 # If the response has a tag starting with 'image/' enable an external
5728 # filter that only applies to images.
5730 # Note that the filter is not available by default, it's just a
5731 # <literal><link linkend="external-filter-syntax">silly example</link></literal>.
5732 {+external-filter{rotate-image} +force-text-mode}
5742 <!-- ~~~~~ New section ~~~~~ -->
5743 <sect3 renderas="sect4" id="session-cookies-only">
5744 <title>session-cookies-only</title>
5748 <term>Typical use:</term>
5751 Allow only temporary <quote>session</quote> cookies (for the current
5752 browser session <emphasis>only</emphasis>).
5758 <term>Effect:</term>
5761 Deletes the <quote>expires</quote> field from <quote>Set-Cookie:</quote>
5762 server headers. Most browsers will not store such cookies permanently and
5763 forget them in between sessions.
5770 <!-- Boolean, Parameterized, Multi-value -->
5772 <para>Boolean.</para>
5777 <term>Parameter:</term>
5789 This is less strict than <literal><link linkend="crunch-incoming-cookies">crunch-incoming-cookies</link></literal> /
5790 <literal><link linkend="crunch-outgoing-cookies">crunch-outgoing-cookies</link></literal> and allows you to browse
5791 websites that insist or rely on setting cookies, without compromising your privacy too badly.
5794 Most browsers will not permanently store cookies that have been processed by
5795 <literal>session-cookies-only</literal> and will forget about them between sessions.
5796 This makes profiling cookies useless, but won't break sites which require cookies so
5797 that you can log in for transactions. This is generally turned on for all
5798 sites, and is the recommended setting.
5801 It makes <emphasis>no sense at all</emphasis> to use <literal>session-cookies-only</literal>
5802 together with <literal><link linkend="crunch-incoming-cookies">crunch-incoming-cookies</link></literal> or
5803 <literal><link linkend="crunch-outgoing-cookies">crunch-outgoing-cookies</link></literal>. If you do, cookies
5804 will be plainly killed.
5807 Note that it is up to the browser how it handles such cookies without an <quote>expires</quote>
5808 field. If you use an exotic browser, you might want to try it out to be sure.
5811 This setting also has no effect on cookies that may have been stored
5812 previously by the browser before starting <application>Privoxy</application>.
5813 These would have to be removed manually.
5816 <application>Privoxy</application> also uses
5817 the <link linkend="filter-content-cookies">content-cookies filter</link>
5818 to block some types of cookies. Content cookies are not effected by
5819 <literal>session-cookies-only</literal>.
5825 <term>Example usage:</term>
5827 <screen>+session-cookies-only</screen>
5834 <!-- ~~~~~ New section ~~~~~ -->
5835 <sect3 renderas="sect4" id="set-image-blocker">
5836 <title>set-image-blocker</title>
5840 <term>Typical use:</term>
5842 <para>Choose the replacement for blocked images</para>
5847 <term>Effect:</term>
5850 This action alone doesn't do anything noticeable. If <emphasis>both</emphasis>
5851 <literal><link linkend="block">block</link></literal> <emphasis>and</emphasis> <literal><link
5852 linkend="handle-as-image">handle-as-image</link></literal> <emphasis>also</emphasis>
5853 apply, i.e. if the request is to be blocked as an image,
5854 <emphasis>then</emphasis> the parameter of this action decides what will be
5855 sent as a replacement.
5862 <!-- Boolean, Parameterized, Multi-value -->
5864 <para>Parameterized.</para>
5869 <term>Parameter:</term>
5874 <quote>pattern</quote> to send a built-in checkerboard pattern image. The image is visually
5875 decent, scales very well, and makes it obvious where banners were busted.
5880 <quote>blank</quote> to send a built-in transparent image. This makes banners disappear
5881 completely, but makes it hard to detect where <application>Privoxy</application> has blocked
5882 images on a given page and complicates troubleshooting if <application>Privoxy</application>
5883 has blocked innocent images, like navigation icons.
5888 <quote><replaceable class="parameter">target-url</replaceable></quote> to
5889 send a redirect to <replaceable class="parameter">target-url</replaceable>. You can redirect
5890 to any image anywhere, even in your local filesystem via <quote>file:///</quote> URL.
5891 (But note that not all browsers support redirecting to a local file system).
5894 A good application of redirects is to use special <application>Privoxy</application>-built-in
5895 URLs, which send the built-in images, as <replaceable class="parameter">target-url</replaceable>.
5896 This has the same visual effect as specifying <quote>blank</quote> or <quote>pattern</quote> in
5897 the first place, but enables your browser to cache the replacement image, instead of requesting
5898 it over and over again.
5909 The URLs for the built-in images are <quote>http://config.privoxy.org/send-banner?type=<replaceable
5910 class="parameter">type</replaceable></quote>, where <replaceable class="parameter">type</replaceable> is
5911 either <quote>blank</quote> or <quote>pattern</quote>.
5914 There is a third (advanced) type, called <quote>auto</quote>. It is <emphasis>NOT</emphasis> to be
5915 used in <literal>set-image-blocker</literal>, but meant for use from <link linkend="filter-file">filters</link>.
5916 Auto will select the type of image that would have applied to the referring page, had it been an image.
5922 <term>Example usage:</term>
5927 <screen>+set-image-blocker{pattern}</screen>
5929 Redirect to the BSD daemon:
5931 <screen>+set-image-blocker{http://www.freebsd.org/gifs/dae_up3.gif}</screen>
5933 Redirect to the built-in pattern for better caching:
5935 <screen>+set-image-blocker{http://config.privoxy.org/send-banner?type=pattern}</screen>
5942 <!-- ~~~~~ New section ~~~~~ -->
5943 <sect3 id="summary">
5944 <title>Summary</title>
5946 Note that many of these actions have the potential to cause a page to
5947 misbehave, possibly even not to display at all. There are many ways
5948 a site designer may choose to design his site, and what HTTP header
5949 content, and other criteria, he may depend on. There is no way to have hard
5950 and fast rules for all sites. See the <link
5951 linkend="ACTIONSANAT">Appendix</link> for a brief example on troubleshooting
5957 <!-- ~~~~~ New section ~~~~~ -->
5958 <sect2 id="aliases">
5959 <title>Aliases</title>
5961 Custom <quote>actions</quote>, known to <application>Privoxy</application>
5962 as <quote>aliases</quote>, can be defined by combining other actions.
5963 These can in turn be invoked just like the built-in actions.
5964 Currently, an alias name can contain any character except space, tab,
5966 <quote>{</quote> and <quote>}</quote>, but we <emphasis>strongly
5967 recommend</emphasis> that you only use <quote>a</quote> to <quote>z</quote>,
5968 <quote>0</quote> to <quote>9</quote>, <quote>+</quote>, and <quote>-</quote>.
5969 Alias names are not case sensitive, and are not required to start with a
5970 <quote>+</quote> or <quote>-</quote> sign, since they are merely textually
5974 Aliases can be used throughout the actions file, but they <emphasis>must be
5975 defined in a special section at the top of the file!</emphasis>
5976 And there can only be one such section per actions file. Each actions file may
5977 have its own alias section, and the aliases defined in it are only visible
5981 There are two main reasons to use aliases: One is to save typing for frequently
5982 used combinations of actions, the other one is a gain in flexibility: If you
5983 decide once how you want to handle shops by defining an alias called
5984 <quote>shop</quote>, you can later change your policy on shops in
5985 <emphasis>one</emphasis> place, and your changes will take effect everywhere
5986 in the actions file where the <quote>shop</quote> alias is used. Calling aliases
5987 by their purpose also makes your actions files more readable.
5990 Currently, there is one big drawback to using aliases, though:
5991 <application>Privoxy</application>'s built-in web-based action file
5992 editor honors aliases when reading the actions files, but it expands
5993 them before writing. So the effects of your aliases are of course preserved,
5994 but the aliases themselves are lost when you edit sections that use aliases
5999 Now let's define some aliases...
6003 # Useful custom aliases we can use later.
6005 # Note the (required!) section header line and that this section
6006 # must be at the top of the actions file!
6010 # These aliases just save typing later:
6011 # (Note that some already use other aliases!)
6013 +crunch-all-cookies = +<link linkend="CRUNCH-INCOMING-COOKIES">crunch-incoming-cookies</link> +<link linkend="CRUNCH-OUTGOING-COOKIES">crunch-outgoing-cookies</link>
6014 -crunch-all-cookies = -<link linkend="CRUNCH-INCOMING-COOKIES">crunch-incoming-cookies</link> -<link linkend="CRUNCH-OUTGOING-COOKIES">crunch-outgoing-cookies</link>
6015 +block-as-image = +block{Blocked image.} +handle-as-image
6016 allow-all-cookies = -crunch-all-cookies -<link linkend="SESSION-COOKIES-ONLY">session-cookies-only</link> -<link linkend="FILTER-CONTENT-COOKIES">filter{content-cookies}</link>
6018 # These aliases define combinations of actions
6019 # that are useful for certain types of sites:
6021 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>
6023 shop = -crunch-all-cookies -<link linkend="FILTER-ALL-POPUPS">filter{all-popups}</link>
6025 # Short names for other aliases, for really lazy people ;-)
6027 c0 = +crunch-all-cookies
6028 c1 = -crunch-all-cookies</screen>
6031 ...and put them to use. These sections would appear in the lower part of an
6032 actions file and define exceptions to the default actions (as specified further
6033 up for the <quote>/</quote> pattern):
6037 # These sites are either very complex or very keen on
6038 # user data and require minimal interference to work:
6041 .office.microsoft.com
6042 .windowsupdate.microsoft.com
6043 # Gmail is really mail.google.com, not gmail.com
6047 # Allow cookies (for setting and retrieving your customer data)
6051 .worldpay.com # for quietpc.com
6054 # These shops require pop-ups:
6056 {-filter{all-popups} -filter{unsolicited-popups}}
6058 .overclockers.co.uk</screen>
6061 Aliases like <quote>shop</quote> and <quote>fragile</quote> are typically used for
6062 <quote>problem</quote> sites that require more than one action to be disabled
6063 in order to function properly.
6069 <!-- ~~~~~ New section ~~~~~ -->
6070 <sect2 id="act-examples">
6071 <title>Actions Files Tutorial</title>
6073 The above chapters have shown <link linkend="actions-file">which actions files
6074 there are and how they are organized</link>, how actions are <link
6075 linkend="actions">specified</link> and <link linkend="actions-apply">applied
6076 to URLs</link>, how <link linkend="af-patterns">patterns</link> work, and how to
6077 define and use <link linkend="aliases">aliases</link>. Now, let's look at an
6078 example <filename>match-all.action</filename>, <filename>default.action</filename>
6079 and <filename>user.action</filename> file and see how all these pieces come together:
6082 <sect3 id="match-all">
6083 <title>match-all.action</title>
6085 Remember <emphasis>all actions are disabled when matching starts</emphasis>,
6086 so we have to explicitly enable the ones we want.
6090 While the <filename>match-all.action</filename> file only contains a
6091 single section, it is probably the most important one. It has only one
6092 pattern, <quote><literal>/</literal></quote>, but this pattern
6093 <link linkend="af-patterns">matches all URLs</link>. Therefore, the set of
6094 actions used in this <quote>default</quote> section <emphasis>will
6095 be applied to all requests as a start</emphasis>. It can be partly or
6096 wholly overridden by other actions files like <filename>default.action</filename>
6097 and <filename>user.action</filename>, but it will still be largely responsible
6098 for your overall browsing experience.
6102 Again, at the start of matching, all actions are disabled, so there is
6103 no need to disable any actions here. (Remember: a <quote>+</quote>
6104 preceding the action name enables the action, a <quote>-</quote> disables!).
6105 Also note how this long line has been made more readable by splitting it into
6106 multiple lines with line continuation.
6111 +<link linkend="CHANGE-X-FORWARDED-FOR">change-x-forwarded-for{block}</link> \
6112 +<link linkend="HIDE-FROM-HEADER">hide-from-header{block}</link> \
6113 +<link linkend="SET-IMAGE-BLOCKER">set-image-blocker{pattern}</link> \
6119 The default behavior is now set.
6123 <sect3 id="default-action">
6124 <title>default.action</title>
6127 If you aren't a developer, there's no need for you to edit the
6128 <filename>default.action</filename> file. It is maintained by
6129 the &my-app; developers and if you disagree with some of the
6130 sections, you should overrule them in your <filename>user.action</filename>.
6134 Understanding the <filename>default.action</filename> file can
6135 help you with your <filename>user.action</filename>, though.
6139 The first section in this file is a special section for internal use
6140 that prevents older &my-app; versions from reading the file:
6144 ##########################################################################
6145 # Settings -- Don't change! For internal Privoxy use ONLY.
6146 ##########################################################################
6148 for-privoxy-version=3.0.11</screen>
6151 After that comes the (optional) alias section. We'll use the example
6152 section from the above <link linkend="aliases">chapter on aliases</link>,
6153 that also explains why and how aliases are used:
6157 ##########################################################################
6159 ##########################################################################
6162 # These aliases just save typing later:
6163 # (Note that some already use other aliases!)
6165 +crunch-all-cookies = +<link linkend="CRUNCH-INCOMING-COOKIES">crunch-incoming-cookies</link> +<link linkend="CRUNCH-OUTGOING-COOKIES">crunch-outgoing-cookies</link>
6166 -crunch-all-cookies = -<link linkend="CRUNCH-INCOMING-COOKIES">crunch-incoming-cookies</link> -<link linkend="CRUNCH-OUTGOING-COOKIES">crunch-outgoing-cookies</link>
6167 +block-as-image = +block{Blocked image.} +handle-as-image
6168 mercy-for-cookies = -crunch-all-cookies -<link linkend="SESSION-COOKIES-ONLY">session-cookies-only</link> -<link linkend="FILTER-CONTENT-COOKIES">filter{content-cookies}</link>
6170 # These aliases define combinations of actions
6171 # that are useful for certain types of sites:
6173 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>
6174 shop = -crunch-all-cookies -<link linkend="FILTER-ALL-POPUPS">filter{all-popups}</link></screen>
6177 The first of our specialized sections is concerned with <quote>fragile</quote>
6178 sites, i.e. sites that require minimum interference, because they are either
6179 very complex or very keen on tracking you (and have mechanisms in place that
6180 make them unusable for people who avoid being tracked). We will use
6181 our pre-defined <literal>fragile</literal> alias instead of stating the list
6182 of actions explicitly:
6186 ##########################################################################
6187 # Exceptions for sites that'll break under the default action set:
6188 ##########################################################################
6190 # "Fragile" Use a minimum set of actions for these sites (see alias above):
6193 .office.microsoft.com # surprise, surprise!
6194 .windowsupdate.microsoft.com
6195 mail.google.com</screen>
6198 Shopping sites are not as fragile, but they typically
6199 require cookies to log in, and pop-up windows for shopping
6200 carts or item details. Again, we'll use a pre-defined alias:
6208 .worldpay.com # for quietpc.com
6210 .scan.co.uk</screen>
6213 The <literal><link linkend="FAST-REDIRECTS">fast-redirects</link></literal>
6214 action, which may have been enabled in <filename>match-all.action</filename>,
6215 breaks some sites. So disable it for popular sites where we know it misbehaves:
6219 { -<link linkend="FAST-REDIRECTS">fast-redirects</link> }
6223 .altavista.com/.*(like|url|link):http
6224 .altavista.com/trans.*urltext=http
6225 .nytimes.com</screen>
6228 It is important that <application>Privoxy</application> knows which
6229 URLs belong to images, so that <emphasis>if</emphasis> they are to
6230 be blocked, a substitute image can be sent, rather than an HTML page.
6231 Contacting the remote site to find out is not an option, since it
6232 would destroy the loading time advantage of banner blocking, and it
6233 would feed the advertisers information about you. We can mark any
6234 URL as an image with the <literal><link
6235 linkend="handle-as-image">handle-as-image</link></literal> action,
6236 and marking all URLs that end in a known image file extension is a
6241 ##########################################################################
6243 ##########################################################################
6245 # Define which file types will be treated as images, in case they get
6246 # blocked further down this file:
6248 { +<link linkend="HANDLE-AS-IMAGE">handle-as-image</link> }
6249 /.*\.(gif|jpe?g|png|bmp|ico)$</screen>
6252 And then there are known banner sources. They often use scripts to
6253 generate the banners, so it won't be visible from the URL that the
6254 request is for an image. Hence we block them <emphasis>and</emphasis>
6255 mark them as images in one go, with the help of our
6256 <literal>+block-as-image</literal> alias defined above. (We could of
6257 course just as well use <literal>+<link linkend="block">block</link>
6258 +<link linkend="handle-as-image">handle-as-image</link></literal> here.)
6259 Remember that the type of the replacement image is chosen by the
6260 <literal><link linkend="set-image-blocker">set-image-blocker</link></literal>
6261 action. Since all URLs have matched the default section with its
6262 <literal>+<link linkend="set-image-blocker">set-image-blocker</link>{pattern}</literal>
6263 action before, it still applies and needn't be repeated:
6267 # Known ad generators:
6272 .ad.*.doubleclick.net
6273 .a.yimg.com/(?:(?!/i/).)*$
6274 .a[0-9].yimg.com/(?:(?!/i/).)*$
6279 One of the most important jobs of <application>Privoxy</application>
6280 is to block banners. Many of these can be <quote>blocked</quote>
6281 by the <literal><link linkend="filter">filter</link>{banners-by-size}</literal>
6282 action, which we enabled above, and which deletes the references to banner
6283 images from the pages while they are loaded, so the browser doesn't request
6284 them anymore, and hence they don't need to be blocked here. But this naturally
6285 doesn't catch all banners, and some people choose not to use filters, so we
6286 need a comprehensive list of patterns for banner URLs here, and apply the
6287 <literal><link linkend="block">block</link></literal> action to them.
6290 First comes many generic patterns, which do most of the work, by
6291 matching typical domain and path name components of banners. Then comes
6292 a list of individual patterns for specific sites, which is omitted here
6293 to keep the example short:
6297 ##########################################################################
6298 # Block these fine banners:
6299 ##########################################################################
6300 { <link linkend="BLOCK">+block{Banner ads.}</link> }
6308 /.*count(er)?\.(pl|cgi|exe|dll|asp|php[34]?)
6309 /(?:.*/)?(publicite|werbung|rekla(ma|me|am)|annonse|maino(kset|nta|s)?)/
6311 # Site-specific patterns (abbreviated):
6313 .hitbox.com</screen>
6316 It's quite remarkable how many advertisers actually call their banner
6317 servers ads.<replaceable>company</replaceable>.com, or call the directory
6318 in which the banners are stored literally <quote>banners</quote>. So the above
6319 generic patterns are surprisingly effective.
6322 But being very generic, they necessarily also catch URLs that we don't want
6323 to block. The pattern <literal>.*ads.</literal> e.g. catches
6324 <quote>nasty-<emphasis>ads</emphasis>.nasty-corp.com</quote> as intended,
6325 but also <quote>downlo<emphasis>ads</emphasis>.sourcefroge.net</quote> or
6326 <quote><emphasis>ads</emphasis>l.some-provider.net.</quote> So here come some
6327 well-known exceptions to the <literal>+<link linkend="BLOCK">block</link></literal>
6331 Note that these are exceptions to exceptions from the default! Consider the URL
6332 <quote>downloads.sourcefroge.net</quote>: Initially, all actions are deactivated,
6333 so it wouldn't get blocked. Then comes the defaults section, which matches the
6334 URL, but just deactivates the <literal><link linkend="BLOCK">block</link></literal>
6335 action once again. Then it matches <literal>.*ads.</literal>, an exception to the
6336 general non-blocking policy, and suddenly
6337 <literal><link linkend="BLOCK">+block</link></literal> applies. And now, it'll match
6338 <literal>.*loads.</literal>, where <literal><link linkend="BLOCK">-block</link></literal>
6339 applies, so (unless it matches <emphasis>again</emphasis> further down) it ends up
6340 with no <literal><link linkend="BLOCK">block</link></literal> action applying.
6344 ##########################################################################
6345 # Save some innocent victims of the above generic block patterns:
6346 ##########################################################################
6350 { -<link linkend="BLOCK">block</link> }
6351 adv[io]*. # (for advogato.org and advice.*)
6352 adsl. # (has nothing to do with ads)
6353 adobe. # (has nothing to do with ads either)
6354 ad[ud]*. # (adult.* and add.*)
6355 .edu # (universities don't host banners (yet!))
6356 .*loads. # (downloads, uploads etc)
6364 www.globalintersec.com/adv # (adv = advanced)
6365 www.ugu.com/sui/ugu/adv</screen>
6368 Filtering source code can have nasty side effects,
6369 so make an exception for our friends at sourceforge.net,
6370 and all paths with <quote>cvs</quote> in them. Note that
6371 <literal>-<link linkend="FILTER">filter</link></literal>
6372 disables <emphasis>all</emphasis> filters in one fell swoop!
6376 # Don't filter code!
6378 { -<link linkend="FILTER">filter</link> }
6383 .sourceforge.net</screen>
6386 The actual <filename>default.action</filename> is of course much more
6387 comprehensive, but we hope this example made clear how it works.
6392 <sect3 id="user-action"><title>user.action</title>
6395 So far we are painting with a broad brush by setting general policies,
6396 which would be a reasonable starting point for many people. Now,
6397 you might want to be more specific and have customized rules that
6398 are more suitable to your personal habits and preferences. These would
6399 be for narrowly defined situations like your ISP or your bank, and should
6400 be placed in <filename>user.action</filename>, which is parsed after all other
6401 actions files and hence has the last word, over-riding any previously
6402 defined actions. <filename>user.action</filename> is also a
6403 <emphasis>safe</emphasis> place for your personal settings, since
6404 <filename>default.action</filename> is actively maintained by the
6405 <application>Privoxy</application> developers and you'll probably want
6406 to install updated versions from time to time.
6410 So let's look at a few examples of things that one might typically do in
6411 <filename>user.action</filename>:
6415 <!-- brief sample user.action here -->
6418 # My user.action file. <fred@example.com></screen>
6421 As <link linkend="aliases">aliases</link> are local to the actions
6422 file that they are defined in, you can't use the ones from
6423 <filename>default.action</filename>, unless you repeat them here:
6427 # Aliases are local to the file they are defined in.
6428 # (Re-)define aliases for this file:
6432 # These aliases just save typing later, and the alias names should
6433 # be self explanatory.
6435 +crunch-all-cookies = +crunch-incoming-cookies +crunch-outgoing-cookies
6436 -crunch-all-cookies = -crunch-incoming-cookies -crunch-outgoing-cookies
6437 allow-all-cookies = -crunch-all-cookies -session-cookies-only
6438 allow-popups = -filter{all-popups}
6439 +block-as-image = +block{Blocked as image.} +handle-as-image
6440 -block-as-image = -block
6442 # These aliases define combinations of actions that are useful for
6443 # certain types of sites:
6445 fragile = -block -crunch-all-cookies -filter -fast-redirects -hide-referrer
6446 shop = -crunch-all-cookies allow-popups
6448 # Allow ads for selected useful free sites:
6450 allow-ads = -block -filter{banners-by-size} -filter{banners-by-link}
6452 # Alias for specific file types that are text, but might have conflicting
6453 # MIME types. We want the browser to force these to be text documents.
6454 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>
6457 Say you have accounts on some sites that you visit regularly, and
6458 you don't want to have to log in manually each time. So you'd like
6459 to allow persistent cookies for these sites. The
6460 <literal>allow-all-cookies</literal> alias defined above does exactly
6461 that, i.e. it disables crunching of cookies in any direction, and the
6462 processing of cookies to make them only temporary.
6466 { allow-all-cookies }
6470 .redhat.com</screen>
6473 Your bank is allergic to some filter, but you don't know which, so you disable them all:
6477 { -<link linkend="FILTER">filter</link> }
6478 .your-home-banking-site.com</screen>
6481 Some file types you may not want to filter for various reasons:
6485 # Technical documentation is likely to contain strings that might
6486 # erroneously get altered by the JavaScript-oriented filters:
6491 # And this stupid host sends streaming video with a wrong MIME type,
6492 # so that Privoxy thinks it is getting HTML and starts filtering:
6494 stupid-server.example.com/</screen>
6497 Example of a simple <link linkend="BLOCK">block</link> action. Say you've
6498 seen an ad on your favourite page on example.com that you want to get rid of.
6499 You have right-clicked the image, selected <quote>copy image location</quote>
6500 and pasted the URL below while removing the leading http://, into a
6501 <literal>{ +block{} }</literal> section. Note that <literal>{ +handle-as-image
6502 }</literal> need not be specified, since all URLs ending in
6503 <literal>.gif</literal> will be tagged as images by the general rules as set
6504 in default.action anyway:
6508 { +<link linkend="BLOCK">block</link>{Nasty ads.} }
6509 www.example.com/nasty-ads/sponsor\.gif
6510 another.example.net/more/junk/here/</screen>
6513 The URLs of dynamically generated banners, especially from large banner
6514 farms, often don't use the well-known image file name extensions, which
6515 makes it impossible for <application>Privoxy</application> to guess
6516 the file type just by looking at the URL.
6517 You can use the <literal>+block-as-image</literal> alias defined above for
6519 Note that objects which match this rule but then turn out NOT to be an
6520 image are typically rendered as a <quote>broken image</quote> icon by the
6521 browser. Use cautiously.
6529 ar.atwola.com/</screen>
6532 Now you noticed that the default configuration breaks Forbes Magazine,
6533 but you were too lazy to find out which action is the culprit, and you
6534 were again too lazy to give <link linkend="contact">feedback</link>, so
6535 you just used the <literal>fragile</literal> alias on the site, and
6536 -- <emphasis>whoa!</emphasis> -- it worked. The <literal>fragile</literal>
6537 aliases disables those actions that are most likely to break a site. Also,
6538 good for testing purposes to see if it is <application>Privoxy</application>
6539 that is causing the problem or not. We later find other regular sites
6540 that misbehave, and add those to our personalized list of troublemakers:
6547 .mybank.com</screen>
6550 You like the <quote>fun</quote> text replacements in <filename>default.filter</filename>,
6551 but it is disabled in the distributed actions file.
6552 So you'd like to turn it on in your private,
6553 update-safe config, once and for all:
6557 { +<link linkend="filter-fun">filter{fun}</link> }
6558 / # For ALL sites!</screen>
6561 Note that the above is not really a good idea: There are exceptions
6562 to the filters in <filename>default.action</filename> for things that
6563 really shouldn't be filtered, like code on CVS->Web interfaces. Since
6564 <filename>user.action</filename> has the last word, these exceptions
6565 won't be valid for the <quote>fun</quote> filtering specified here.
6569 You might also worry about how your favourite free websites are
6570 funded, and find that they rely on displaying banner advertisements
6571 to survive. So you might want to specifically allow banners for those
6572 sites that you feel provide value to you:
6582 Note that <literal>allow-ads</literal> has been aliased to
6583 <literal>-<link linkend="block">block</link></literal>,
6584 <literal>-<link linkend="filter-banners-by-size">filter{banners-by-size}</link></literal>, and
6585 <literal>-<link linkend="filter-banners-by-link">filter{banners-by-link}</link></literal> above.
6589 Invoke another alias here to force an over-ride of the MIME type <literal>
6590 application/x-sh</literal> which typically would open a download type
6591 dialog. In my case, I want to look at the shell script, and then I can save
6592 it should I choose to.
6600 <filename>user.action</filename> is generally the best place to define
6601 exceptions and additions to the default policies of
6602 <filename>default.action</filename>. Some actions are safe to have their
6603 default policies set here though. So let's set a default policy to have a
6604 <quote>blank</quote> image as opposed to the checkerboard pattern for
6605 <emphasis>ALL</emphasis> sites. <quote>/</quote> of course matches all URL
6610 { +<link linkend="set-image-blocker">set-image-blocker{blank}</link> }
6611 / # ALL sites</screen>
6616 <!-- ~ End section ~ -->
6620 <!-- ~ End section ~ -->
6622 <!-- ~~~~~~~~ New section Header ~~~~~~~~~ -->
6624 <sect1 id="filter-file">
6625 <title>Filter Files</title>
6628 On-the-fly text substitutions need
6629 to be defined in a <quote>filter file</quote>. Once defined, they
6630 can then be invoked as an <quote>action</quote>.
6634 &my-app; supports three different pcrs-based filter actions:
6635 <literal><link linkend="filter">filter</link></literal> to
6636 rewrite the content that is send to the client,
6637 <literal><link linkend="client-header-filter">client-header-filter</link></literal>
6638 to rewrite headers that are send by the client, and
6639 <literal><link linkend="server-header-filter">server-header-filter</link></literal>
6640 to rewrite headers that are send by the server.
6644 &my-app; also supports two tagger actions:
6645 <literal><link linkend="client-header-tagger">client-header-tagger</link></literal>
6647 <literal><link linkend="server-header-tagger">server-header-tagger</link></literal>.
6648 Taggers and filters use the same syntax in the filter files, the difference
6649 is that taggers don't modify the text they are filtering, but use a rewritten
6650 version of the filtered text as tag. The tags can then be used to change the
6651 applying actions through sections with <link linkend="tag-pattern">tag-patterns</link>.
6655 Finally &my-app; supports the
6656 <literal><link linkend="external-filter">external-filter</link></literal> action
6657 to enable <literal><link linkend="external-filter-syntax">external filters</link></literal>
6658 written in proper programming languages.
6663 Multiple filter files can be defined through the <literal> <link
6664 linkend="filterfile">filterfile</link></literal> config directive. The filters
6665 as supplied by the developers are located in
6666 <filename>default.filter</filename>. It is recommended that any locally
6667 defined or modified filters go in a separately defined file such as
6668 <filename>user.filter</filename>.
6672 Common tasks for content filters are to eliminate common annoyances in
6673 HTML and JavaScript, such as pop-up windows,
6674 exit consoles, crippled windows without navigation tools, the
6675 infamous <BLINK> tag etc, to suppress images with certain
6676 width and height attributes (standard banner sizes or web-bugs),
6677 or just to have fun.
6681 Enabled content filters are applied to any content whose
6682 <quote>Content Type</quote> header is recognised as a sign
6683 of text-based content, with the exception of <literal>text/plain</literal>.
6684 Use the <link linkend="FORCE-TEXT-MODE">force-text-mode</link> action
6685 to also filter other content.
6689 Substitutions are made at the source level, so if you want to <quote>roll
6690 your own</quote> filters, you should first be familiar with HTML syntax,
6691 and, of course, regular expressions.
6695 Just like the <link linkend="actions-file">actions files</link>, the
6696 filter file is organized in sections, which are called <emphasis>filters</emphasis>
6697 here. Each filter consists of a heading line, that starts with one of the
6698 <emphasis>keywords</emphasis> <literal>FILTER:</literal>,
6699 <literal>CLIENT-HEADER-FILTER:</literal> or <literal>SERVER-HEADER-FILTER:</literal>
6700 followed by the filter's <emphasis>name</emphasis>, and a short (one line)
6701 <emphasis>description</emphasis> of what it does. Below that line
6702 come the <emphasis>jobs</emphasis>, i.e. lines that define the actual
6703 text substitutions. By convention, the name of a filter
6704 should describe what the filter <emphasis>eliminates</emphasis>. The
6705 comment is used in the <ulink url="http://config.privoxy.org/">web-based
6706 user interface</ulink>.
6710 Once a filter called <replaceable>name</replaceable> has been defined
6711 in the filter file, it can be invoked by using an action of the form
6712 +<literal><link linkend="filter">filter</link>{<replaceable>name</replaceable>}</literal>
6713 in any <link linkend="actions-file">actions file</link>.
6717 Filter definitions start with a header line that contains the filter
6718 type, the filter name and the filter description.
6719 A content filter header line for a filter called <quote>foo</quote> could look
6723 <screen>FILTER: foo Replace all "foo" with "bar"</screen>
6726 Below that line, and up to the next header line, come the jobs that
6727 define what text replacements the filter executes. They are specified
6728 in a syntax that imitates <ulink url="http://www.perl.org/">Perl</ulink>'s
6729 <literal>s///</literal> operator. If you are familiar with Perl, you
6730 will find this to be quite intuitive, and may want to look at the
6731 PCRS documentation for the subtle differences to Perl behaviour.
6735 Most notably, the non-standard option letter <literal>U</literal> is supported,
6736 which turns the default to ungreedy matching (add <literal>?</literal> to
6737 quantifiers to turn them greedy again).
6741 The non-standard option letter <literal>D</literal> (dynamic) allows
6742 to use the variables $host, $origin (the IP address the request came from),
6743 $path, $url and $listen-address (the address on which Privoxy accepted the
6744 client request. Example: 127.0.0.1:8118).
6745 They will be replaced with the value they refer to before the filter
6750 Note that '$' is a bad choice for a delimiter in a dynamic filter as you
6751 might end up with unintended variables if you use a variable name
6752 directly after the delimiter. Variables will be resolved without
6753 escaping anything, therefore you also have to be careful not to chose
6754 delimiters that appear in the replacement text. For example '<' should
6755 be save, while '?' will sooner or later cause conflicts with $url.
6759 The non-standard option letter <literal>T</literal> (trivial) prevents
6760 parsing for backreferences in the substitute. Use it if you want to include
6761 text like '$&' in your substitute without quoting.
6766 <ulink url="http://en.wikipedia.org/wiki/Regular_expressions"><quote>Regular
6767 Expressions</quote></ulink>, you might want to take a look at
6768 the <link linkend="regex">Appendix on regular expressions</link>, and
6769 see the <ulink url="http://perldoc.perl.org/perlre.html">Perl
6771 <ulink url="http://perldoc.perl.org/perlop.html">the
6772 <literal>s///</literal> operator's syntax</ulink> and <ulink
6773 url="http://perldoc.perl.org/perlre.html">Perl-style regular
6774 expressions</ulink> in general.
6775 The below examples might also help to get you started.
6779 <!-- ~~~~~~~~ New section Header ~~~~~~~~~ -->
6781 <sect2 id="filter-file-tut"><title>Filter File Tutorial</title>
6783 Now, let's complete our <quote>foo</quote> content filter. We have already defined
6784 the heading, but the jobs are still missing. Since all it does is to replace
6785 <quote>foo</quote> with <quote>bar</quote>, there is only one (trivial) job
6789 <screen>s/foo/bar/</screen>
6792 But wait! Didn't the comment say that <emphasis>all</emphasis> occurrences
6793 of <quote>foo</quote> should be replaced? Our current job will only take
6794 care of the first <quote>foo</quote> on each page. For global substitution,
6795 we'll need to add the <literal>g</literal> option:
6798 <screen>s/foo/bar/g</screen>
6801 Our complete filter now looks like this:
6804 <screen>FILTER: foo Replace all "foo" with "bar"
6805 s/foo/bar/g</screen>
6808 Let's look at some real filters for more interesting examples. Here you see
6809 a filter that protects against some common annoyances that arise from JavaScript
6810 abuse. Let's look at its jobs one after the other:
6815 FILTER: js-annoyances Get rid of particularly annoying JavaScript abuse
6817 # Get rid of JavaScript referrer tracking. Test page: http://www.randomoddness.com/untitled.htm
6819 s|(<script.*)document\.referrer(.*</script>)|$1"Not Your Business!"$2|Usg</screen>
6822 Following the header line and a comment, you see the job. Note that it uses
6823 <literal>|</literal> as the delimiter instead of <literal>/</literal>, because
6824 the pattern contains a forward slash, which would otherwise have to be escaped
6825 by a backslash (<literal>\</literal>).
6829 Now, let's examine the pattern: it starts with the text <literal><script.*</literal>
6830 enclosed in parentheses. Since the dot matches any character, and <literal>*</literal>
6831 means: <quote>Match an arbitrary number of the element left of myself</quote>, this
6832 matches <quote><script</quote>, followed by <emphasis>any</emphasis> text, i.e.
6833 it matches the whole page, from the start of the first <script> tag.
6837 That's more than we want, but the pattern continues: <literal>document\.referrer</literal>
6838 matches only the exact string <quote>document.referrer</quote>. The dot needed to
6839 be <emphasis>escaped</emphasis>, i.e. preceded by a backslash, to take away its
6840 special meaning as a joker, and make it just a regular dot. So far, the meaning is:
6841 Match from the start of the first <script> tag in a the page, up to, and including,
6842 the text <quote>document.referrer</quote>, if <emphasis>both</emphasis> are present
6843 in the page (and appear in that order).
6847 But there's still more pattern to go. The next element, again enclosed in parentheses,
6848 is <literal>.*</script></literal>. You already know what <literal>.*</literal>
6849 means, so the whole pattern translates to: Match from the start of the first <script>
6850 tag in a page to the end of the last <script> tag, provided that the text
6851 <quote>document.referrer</quote> appears somewhere in between.
6855 This is still not the whole story, since we have ignored the options and the parentheses:
6856 The portions of the page matched by sub-patterns that are enclosed in parentheses, will be
6857 remembered and be available through the variables <literal>$1, $2, ...</literal> in
6858 the substitute. The <literal>U</literal> option switches to ungreedy matching, which means
6859 that the first <literal>.*</literal> in the pattern will only <quote>eat up</quote> all
6860 text in between <quote><script</quote> and the <emphasis>first</emphasis> occurrence
6861 of <quote>document.referrer</quote>, and that the second <literal>.*</literal> will
6862 only span the text up to the <emphasis>first</emphasis> <quote></script></quote>
6863 tag. Furthermore, the <literal>s</literal> option says that the match may span
6864 multiple lines in the page, and the <literal>g</literal> option again means that the
6865 substitution is global.
6869 So, to summarize, the pattern means: Match all scripts that contain the text
6870 <quote>document.referrer</quote>. Remember the parts of the script from
6871 (and including) the start tag up to (and excluding) the string
6872 <quote>document.referrer</quote> as <literal>$1</literal>, and the part following
6873 that string, up to and including the closing tag, as <literal>$2</literal>.
6877 Now the pattern is deciphered, but wasn't this about substituting things? So
6878 lets look at the substitute: <literal>$1"Not Your Business!"$2</literal> is
6879 easy to read: The text remembered as <literal>$1</literal>, followed by
6880 <literal>"Not Your Business!"</literal> (<emphasis>including</emphasis>
6881 the quotation marks!), followed by the text remembered as <literal>$2</literal>.
6882 This produces an exact copy of the original string, with the middle part
6883 (the <quote>document.referrer</quote>) replaced by <literal>"Not Your
6884 Business!"</literal>.
6888 The whole job now reads: Replace <quote>document.referrer</quote> by
6889 <literal>"Not Your Business!"</literal> wherever it appears inside a
6890 <script> tag. Note that this job won't break JavaScript syntax,
6891 since both the original and the replacement are syntactically valid
6892 string objects. The script just won't have access to the referrer
6893 information anymore.
6897 We'll show you two other jobs from the JavaScript taming department, but
6898 this time only point out the constructs of special interest:
6902 # The status bar is for displaying link targets, not pointless blahblah
6904 s/window\.status\s*=\s*(['"]).*?\1/dUmMy=1/ig</screen>
6907 <literal>\s</literal> stands for whitespace characters (space, tab, newline,
6908 carriage return, form feed), so that <literal>\s*</literal> means: <quote>zero
6909 or more whitespace</quote>. The <literal>?</literal> in <literal>.*?</literal>
6910 makes this matching of arbitrary text ungreedy. (Note that the <literal>U</literal>
6911 option is not set). The <literal>['"]</literal> construct means: <quote>a single
6912 <emphasis>or</emphasis> a double quote</quote>. Finally, <literal>\1</literal> is
6913 a back-reference to the first parenthesis just like <literal>$1</literal> above,
6914 with the difference that in the <emphasis>pattern</emphasis>, a backslash indicates
6915 a back-reference, whereas in the <emphasis>substitute</emphasis>, it's the dollar.
6919 So what does this job do? It replaces assignments of single- or double-quoted
6920 strings to the <quote>window.status</quote> object with a dummy assignment
6921 (using a variable name that is hopefully odd enough not to conflict with
6922 real variables in scripts). Thus, it catches many cases where e.g. pointless
6923 descriptions are displayed in the status bar instead of the link target when
6924 you move your mouse over links.
6928 # Kill OnUnload popups. Yummy. Test: http://www.zdnet.com/zdsubs/yahoo/tree/yfs.html
6930 s/(<body [^>]*)onunload(.*>)/$1never$2/iU</screen>
6934 <ulink url="http://www.w3.org/TR/2000/REC-DOM-Level-2-Events-20001113/events.html#Events-eventgroupings-htmlevents">OnUnload
6935 event binding</ulink> in the HTML DOM was a <emphasis>CRIME</emphasis>.
6936 When I close a browser window, I want it to close and die. Basta.
6937 This job replaces the <quote>onunload</quote> attribute in
6938 <quote><body></quote> tags with the dummy word <literal>never</literal>.
6939 Note that the <literal>i</literal> option makes the pattern matching
6940 case-insensitive. Also note that ungreedy matching alone doesn't always guarantee
6941 a minimal match: In the first parenthesis, we had to use <literal>[^>]*</literal>
6942 instead of <literal>.*</literal> to prevent the match from exceeding the
6943 <body> tag if it doesn't contain <quote>OnUnload</quote>, but the page's
6948 The last example is from the fun department:
6952 FILTER: fun Fun text replacements
6954 # Spice the daily news:
6956 s/microsoft(?!\.com)/MicroSuck/ig</screen>
6959 Note the <literal>(?!\.com)</literal> part (a so-called negative lookahead)
6960 in the job's pattern, which means: Don't match, if the string
6961 <quote>.com</quote> appears directly following <quote>microsoft</quote>
6962 in the page. This prevents links to microsoft.com from being trashed, while
6963 still replacing the word everywhere else.
6967 # Buzzword Bingo (example for extended regex syntax)
6969 s* industry[ -]leading \
6971 | customer[ -]focused \
6972 | market[ -]driven \
6973 | award[ -]winning # Comments are OK, too! \
6974 | high[ -]performance \
6975 | solutions[ -]based \
6979 *<font color="red"><b>BINGO!</b></font> \
6983 The <literal>x</literal> option in this job turns on extended syntax, and allows for
6984 e.g. the liberal use of (non-interpreted!) whitespace for nicer formatting.
6992 <!-- ~~~~~~~~ New section Header ~~~~~~~~~ -->
6994 <sect2 id="predefined-filters"><title>The Pre-defined Filters</title>
6998 Note each filter is also listed in the +filter action section above. Please
6999 keep these listings in sync.
7004 The distribution <filename>default.filter</filename> file contains a selection of
7005 pre-defined filters for your convenience:
7010 <term><emphasis>js-annoyances</emphasis></term>
7013 The purpose of this filter is to get rid of particularly annoying JavaScript abuse.
7019 replaces JavaScript references to the browser's referrer information
7020 with the string "Not Your Business!". This compliments the <literal><link
7021 linkend="hide-referrer">hide-referrer</link></literal> action on the content level.
7026 removes the bindings to the DOM's
7027 <ulink url="http://www.w3.org/TR/2000/REC-DOM-Level-2-Events-20001113/events.html#Events-eventgroupings-htmlevents">unload
7028 event</ulink> which we feel has no right to exist and is responsible for most <quote>exit consoles</quote>, i.e.
7029 nasty windows that pop up when you close another one.
7034 removes code that causes new windows to be opened with undesired properties, such as being
7035 full-screen, non-resizeable, without location, status or menu bar etc.
7040 Use with caution. This is an aggressive filter, and can break sites that
7041 rely heavily on JavaScript.
7047 <term><emphasis>js-events</emphasis></term>
7050 This is a very radical measure. It removes virtually all JavaScript event bindings, which
7051 means that scripts can not react to user actions such as mouse movements or clicks, window
7052 resizing etc, anymore. Use with caution!
7055 We <emphasis>strongly discourage</emphasis> using this filter as a default since it breaks
7056 many legitimate scripts. It is meant for use only on extra-nasty sites (should you really
7063 <term><emphasis>html-annoyances</emphasis></term>
7066 This filter will undo many common instances of HTML based abuse.
7069 The <literal>BLINK</literal> and <literal>MARQUEE</literal> tags
7070 are neutralized (yeah baby!), and browser windows will be created as
7071 resizeable (as of course they should be!), and will have location,
7072 scroll and menu bars -- even if specified otherwise.
7078 <term><emphasis>content-cookies</emphasis></term>
7081 Most cookies are set in the HTTP dialog, where they can be intercepted
7083 <literal><link linkend="crunch-incoming-cookies">crunch-incoming-cookies</link></literal>
7084 and <literal><link linkend="crunch-outgoing-cookies">crunch-outgoing-cookies</link></literal>
7085 actions. But web sites increasingly make use of HTML meta tags and JavaScript
7086 to sneak cookies to the browser on the content level.
7089 This filter disables most HTML and JavaScript code that reads or sets
7090 cookies. It cannot detect all clever uses of these types of code, so it
7091 should not be relied on as an absolute fix. Use it wherever you would also
7092 use the cookie crunch actions.
7098 <term><emphasis>refresh-tags</emphasis></term>
7101 Disable any refresh tags if the interval is greater than nine seconds (so
7102 that redirections done via refresh tags are not destroyed). This is useful
7103 for dial-on-demand setups, or for those who find this HTML feature
7110 <term><emphasis>unsolicited-popups</emphasis></term>
7113 This filter attempts to prevent only <quote>unsolicited</quote> pop-up
7114 windows from opening, yet still allow pop-up windows that the user
7115 has explicitly chosen to open. It was added in version 3.0.1,
7116 as an improvement over earlier such filters.
7119 Technical note: The filter works by redefining the window.open JavaScript
7120 function to a dummy function, <literal>PrivoxyWindowOpen()</literal>,
7121 during the loading and rendering phase of each HTML page access, and
7122 restoring the function afterward.
7125 This is recommended only for browsers that cannot perform this function
7126 reliably themselves. And be aware that some sites require such windows
7127 in order to function normally. Use with caution.
7133 <term><emphasis>all-popups</emphasis></term>
7136 Attempt to prevent <emphasis>all</emphasis> pop-up windows from opening.
7137 Note this should be used with even more discretion than the above, since
7138 it is more likely to break some sites that require pop-ups for normal
7139 usage. Use with caution.
7145 <term><emphasis>img-reorder</emphasis></term>
7148 This is a helper filter that has no value if used alone. It makes the
7149 <literal>banners-by-size</literal> and <literal>banners-by-link</literal>
7150 (see below) filters more effective and should be enabled together with them.
7156 <term><emphasis>banners-by-size</emphasis></term>
7159 This filter removes image tags purely based on what size they are. Fortunately
7160 for us, many ads and banner images tend to conform to certain standardized
7161 sizes, which makes this filter quite effective for ad stripping purposes.
7164 Occasionally this filter will cause false positives on images that are not ads,
7165 but just happen to be of one of the standard banner sizes.
7168 Recommended only for those who require extreme ad blocking. The default
7169 block rules should catch 95+% of all ads <emphasis>without</emphasis> this filter enabled.
7175 <term><emphasis>banners-by-link</emphasis></term>
7178 This is an experimental filter that attempts to kill any banners if
7179 their URLs seem to point to known or suspected click trackers. It is currently
7180 not of much value and is not recommended for use by default.
7186 <term><emphasis>webbugs</emphasis></term>
7189 Webbugs are small, invisible images (technically 1X1 GIF images), that
7190 are used to track users across websites, and collect information on them.
7191 As an HTML page is loaded by the browser, an embedded image tag causes the
7192 browser to contact a third-party site, disclosing the tracking information
7193 through the requested URL and/or cookies for that third-party domain, without
7194 the user ever becoming aware of the interaction with the third-party site.
7195 HTML-ized spam also uses a similar technique to verify email addresses.
7198 This filter removes the HTML code that loads such <quote>webbugs</quote>.
7204 <term><emphasis>tiny-textforms</emphasis></term>
7207 A rather special-purpose filter that can be used to enlarge textareas (those
7208 multi-line text boxes in web forms) and turn off hard word wrap in them.
7209 It was written for the sourceforge.net tracker system where such boxes are
7210 a nuisance, but it can be handy on other sites, too.
7213 It is not recommended to use this filter as a default.
7219 <term><emphasis>jumping-windows</emphasis></term>
7222 Many consider windows that move, or resize themselves to be abusive. This filter
7223 neutralizes the related JavaScript code. Note that some sites might not display
7224 or behave as intended when using this filter. Use with caution.
7230 <term><emphasis>frameset-borders</emphasis></term>
7233 Some web designers seem to assume that everyone in the world will view their
7234 web sites using the same browser brand and version, screen resolution etc,
7235 because only that assumption could explain why they'd use static frame sizes,
7236 yet prevent their frames from being resized by the user, should they be too
7237 small to show their whole content.
7240 This filter removes the related HTML code. It should only be applied to sites
7247 <term><emphasis>demoronizer</emphasis></term>
7250 Many Microsoft products that generate HTML use non-standard extensions (read:
7251 violations) of the ISO 8859-1 aka Latin-1 character set. This can cause those
7252 HTML documents to display with errors on standard-compliant platforms.
7255 This filter translates the MS-only characters into Latin-1 equivalents.
7256 It is not necessary when using MS products, and will cause corruption of
7257 all documents that use 8-bit character sets other than Latin-1. It's mostly
7258 worthwhile for Europeans on non-MS platforms, if weird garbage characters
7259 sometimes appear on some pages, or user agents that don't correct for this on
7262 My version of Mozilla (ancient) shows litte square boxes for quote
7263 characters, and apostrophes on moronized pages. So many pages have this, I
7264 can read them fine now. HB 08/27/06
7271 <term><emphasis>shockwave-flash</emphasis></term>
7274 A filter for shockwave haters. As the name suggests, this filter strips code
7275 out of web pages that is used to embed shockwave flash objects.
7283 <term><emphasis>quicktime-kioskmode</emphasis></term>
7286 Change HTML code that embeds Quicktime objects so that kioskmode, which
7287 prevents saving, is disabled.
7293 <term><emphasis>fun</emphasis></term>
7296 Text replacements for subversive browsing fun. Make fun of your favorite
7297 Monopolist or play buzzword bingo.
7303 <term><emphasis>crude-parental</emphasis></term>
7306 A demonstration-only filter that shows how <application>Privoxy</application>
7307 can be used to delete web content on a keyword basis.
7313 <term><emphasis>ie-exploits</emphasis></term>
7316 An experimental collection of text replacements to disable malicious HTML and JavaScript
7317 code that exploits known security holes in Internet Explorer.
7320 Presently, it only protects against Nimda and a cross-site scripting bug, and
7321 would need active maintenance to provide more substantial protection.
7327 <term><emphasis>site-specifics</emphasis></term>
7330 Some web sites have very specific problems, the cure for which doesn't apply
7331 anywhere else, or could even cause damage on other sites.
7334 This is a collection of such site-specific cures which should only be applied
7335 to the sites they were intended for, which is what the supplied
7336 <filename>default.action</filename> file does. Users shouldn't need to change
7337 anything regarding this filter.
7343 <term><emphasis>google</emphasis></term>
7346 A CSS based block for Google text ads. Also removes a width limitation
7347 and the toolbar advertisement.
7353 <term><emphasis>yahoo</emphasis></term>
7356 Another CSS based block, this time for Yahoo text ads. And removes
7357 a width limitation as well.
7363 <term><emphasis>msn</emphasis></term>
7366 Another CSS based block, this time for MSN text ads. And removes
7367 tracking URLs, as well as a width limitation.
7373 <term><emphasis>blogspot</emphasis></term>
7376 Cleans up some Blogspot blogs. Read the fine print before using this one!
7379 This filter also intentionally removes some navigation stuff and sets the
7380 page width to 100%. As a result, some rounded <quote>corners</quote> would
7381 appear to early or not at all and as fixing this would require a browser
7382 that understands background-size (CSS3), they are removed instead.
7388 <term><emphasis>xml-to-html</emphasis></term>
7391 Server-header filter to change the Content-Type from xml to html.
7397 <term><emphasis>html-to-xml</emphasis></term>
7400 Server-header filter to change the Content-Type from html to xml.
7406 <term><emphasis>no-ping</emphasis></term>
7409 Removes the non-standard <literal>ping</literal> attribute from
7410 anchor and area HTML tags.
7416 <term><emphasis>hide-tor-exit-notation</emphasis></term>
7419 Client-header filter to remove the <command>Tor</command> exit node notation
7420 found in Host and Referer headers.
7423 If &my-app; and <command>Tor</command> are chained and &my-app;
7424 is configured to use socks4a, one can use <quote>http://www.example.org.foobar.exit/</quote>
7425 to access the host <quote>www.example.org</quote> through the
7426 <command>Tor</command> exit node <quote>foobar</quote>.
7429 As the HTTP client isn't aware of this notation, it treats the
7430 whole string <quote>www.example.org.foobar.exit</quote> as host and uses it
7431 for the <quote>Host</quote> and <quote>Referer</quote> headers. From the
7432 server's point of view the resulting headers are invalid and can cause problems.
7435 An invalid <quote>Referer</quote> header can trigger <quote>hot-linking</quote>
7436 protections, an invalid <quote>Host</quote> header will make it impossible for
7437 the server to find the right vhost (several domains hosted on the same IP address).
7440 This client-header filter removes the <quote>foo.exit</quote> part in those headers
7441 to prevent the mentioned problems. Note that it only modifies
7442 the HTTP headers, it doesn't make it impossible for the server
7443 to detect your <command>Tor</command> exit node based on the IP address
7444 the request is coming from.
7451 <term><emphasis> </emphasis></term>
7464 <!-- ~~~~~~~~ New section Header ~~~~~~~~~ -->
7465 <sect2 id="external-filter-syntax"><title>External filter syntax</title>
7467 External filters are scripts or programs that can modify the content in
7468 case common <literal><link linkend="filter">filters</link></literal>
7469 aren't powerful enough.
7472 External filters can be written in any language the platform &my-app; runs
7476 They are controlled with the
7477 <literal><link linkend="external-filter">external-filter</link></literal> action
7478 and have to be defined in the <literal><link linkend="filterfile">filterfile</link></literal>
7482 The header looks like any other filter, but instead of pcrs jobs, external
7483 filters contain a single job which can be a program or a shell script (which
7484 may call other scripts or programs).
7487 External filters read the content from STDIN and write the rewritten
7489 The environment variables PRIVOXY_URL, PRIVOXY_PATH, PRIVOXY_HOST,
7490 PRIVOXY_ORIGIN, PRIVOXY_LISTEN_ADDRESS can be used to get some details
7491 about the client request.
7494 &my-app; will temporary store the content to filter in the
7495 <literal><link linkend="temporary-directory">temporary-directory</link></literal>.
7499 EXTERNAL-FILTER: cat Pointless example filter that doesn't actually modify the content
7502 # Incorrect reimplementation of the filter above in POSIX shell.
7504 # Note that it's a single job that spans multiple lines, the line
7505 # breaks are not passed to the shell, thus the semicolons are required.
7507 # If the script isn't trivial, it is recommended to put it into an external file.
7509 # In general, writing external filters entirely in POSIX shell is not
7510 # considered a good idea.
7511 EXTERNAL-FILTER: cat2 Pointless example filter that despite its name may actually modify the content
7517 EXTERNAL-FILTER: rotate-image Rotate an image by 180 degree. Test filter with limited value.
7518 /usr/local/bin/convert - -rotate 180 -
7520 EXTERNAL-FILTER: citation-needed Adds a "[citation needed]" tag to an image. The coordinates may need adjustment.
7521 /usr/local/bin/convert - -pointsize 16 -fill white -annotate +17+418 "[citation needed]" -
7526 Currently external filters are executed with &my-app;'s privileges!
7527 Only use external filters you understand and trust.
7531 External filters are experimental and the syntax may change in the future.
7537 <!-- ~ End section ~ -->
7541 <!-- ~~~~~ New section ~~~~~ -->
7543 <sect1 id="templates">
7544 <title>Privoxy's Template Files</title>
7546 All <application>Privoxy</application> built-in pages, i.e. error pages such as the
7547 <ulink url="http://show-the-404-error.page"><quote>404 - No Such Domain</quote>
7548 error page</ulink>, the <ulink
7549 url="http://ads.bannerserver.example.com/nasty-ads/sponsor.html"><quote>BLOCKED</quote>
7551 and all pages of its <ulink url="http://config.privoxy.org/">web-based
7552 user interface</ulink>, are generated from <emphasis>templates</emphasis>.
7553 (<application>Privoxy</application> must be running for the above links to work as
7558 These templates are stored in a subdirectory of the <link linkend="confdir">configuration
7559 directory</link> called <filename>templates</filename>. On Unixish platforms,
7561 <ulink url="file:///etc/privoxy/templates/"><filename>/etc/privoxy/templates/</filename></ulink>.
7565 The templates are basically normal HTML files, but with place-holders (called symbols
7566 or exports), which <application>Privoxy</application> fills at run time. It
7567 is possible to edit the templates with a normal text editor, should you want
7568 to customize them. (<emphasis>Not recommended for the casual
7569 user</emphasis>). Should you create your own custom templates, you should use
7570 the <filename>config</filename> setting <link linkend="templdir">templdir</link>
7571 to specify an alternate location, so your templates do not get overwritten
7575 Note that just like in configuration files, lines starting
7576 with <literal>#</literal> are ignored when the templates are filled in.
7580 The place-holders are of the form <literal>@name@</literal>, and you will
7581 find a list of available symbols, which vary from template to template,
7582 in the comments at the start of each file. Note that these comments are not
7583 always accurate, and that it's probably best to look at the existing HTML
7584 code to find out which symbols are supported and what they are filled in with.
7588 A special application of this substitution mechanism is to make whole
7589 blocks of HTML code disappear when a specific symbol is set. We use this
7590 for many purposes, one of them being to include the beta warning in all
7591 our user interface (CGI) pages when <application>Privoxy</application>
7592 is in an alpha or beta development stage:
7596 <!-- @if-unstable-start -->
7598 ... beta warning HTML code goes here ...
7600 <!-- if-unstable-end@ --></screen>
7603 If the "unstable" symbol is set, everything in between and including
7604 <literal>@if-unstable-start</literal> and <literal>if-unstable-end@</literal>
7605 will disappear, leaving nothing but an empty comment:
7608 <screen><!-- --></screen>
7611 There's also an if-then-else construct and an <literal>#include</literal>
7612 mechanism, but you'll sure find out if you are inclined to edit the
7617 All templates refer to a style located at
7618 <ulink url="http://config.privoxy.org/send-stylesheet"><literal>http://config.privoxy.org/send-stylesheet</literal></ulink>.
7619 This is, of course, locally served by <application>Privoxy</application>
7620 and the source for it can be found and edited in the
7621 <filename>cgi-style.css</filename> template.
7626 <!-- ~ End section ~ -->
7630 <!-- ~~~~~ New section ~~~~~ -->
7632 <sect1 id="contact"><title>Contacting the Developers, Bug Reporting and Feature
7635 <!-- Include contacting.sgml boilerplate: -->
7637 <!-- end boilerplate -->
7641 <!-- ~ End section ~ -->
7644 <!-- ~~~~~ New section ~~~~~ -->
7645 <sect1 id="copyright"><title>Privoxy Copyright, License and History</title>
7647 <!-- Include copyright.sgml: -->
7649 <!-- end copyright -->
7652 <application>Privoxy</application> is free software; you can
7653 redistribute it and/or modify it under the terms of the
7654 <citetitle>GNU General Public License</citetitle>, version 2,
7655 as published by the Free Software Foundation and included in
7659 <!-- ~~~~~ New section ~~~~~ -->
7660 <sect2 id="license"><title>License</title>
7662 <screen><![ RCDATA [ &GPLv2; ]]></screen>
7665 <!-- ~ End section ~ -->
7668 <!-- ~~~~~ New section ~~~~~ -->
7670 <sect2 id="history"><title>History</title>
7671 <!-- Include history.sgml: -->
7673 <!-- end history -->
7676 <sect2 id="authors"><title>Authors</title>
7677 <!-- Include p-authors.sgml: -->
7679 <!-- end authors -->
7684 <!-- ~ End section ~ -->
7687 <!-- ~~~~~ New section ~~~~~ -->
7688 <sect1 id="seealso"><title>See Also</title>
7689 <!-- Include seealso.sgml: -->
7691 <!-- end seealso -->
7696 <!-- ~~~~~ New section ~~~~~ -->
7697 <sect1 id="appendix"><title>Appendix</title>
7700 <!-- ~~~~~ New section ~~~~~ -->
7702 <title>Regular Expressions</title>
7704 <application>Privoxy</application> uses Perl-style <quote>regular
7705 expressions</quote> in its <link linkend="actions-file">actions
7706 files</link> and <link linkend="filter-file">filter file</link>,
7707 through the <ulink url="http://www.pcre.org/">PCRE</ulink> and
7710 <ulink url="http://www.oesterhelt.org/pcrs/">PCRS</ulink> libraries.
7712 <application>PCRS</application> libraries.
7716 If you are reading this, you probably don't understand what <quote>regular
7717 expressions</quote> are, or what they can do. So this will be a very brief
7718 introduction only. A full explanation would require a <ulink
7719 url="http://www.oreilly.com/catalog/regex/">book</ulink> ;-)
7723 Regular expressions provide a language to describe patterns that can be
7724 run against strings of characters (letter, numbers, etc), to see if they
7725 match the string or not. The patterns are themselves (sometimes complex)
7726 strings of literal characters, combined with wild-cards, and other special
7727 characters, called meta-characters. The <quote>meta-characters</quote> have
7728 special meanings and are used to build complex patterns to be matched against.
7729 Perl Compatible Regular Expressions are an especially convenient
7730 <quote>dialect</quote> of the regular expression language.
7734 To make a simple analogy, we do something similar when we use wild-card
7735 characters when listing files with the <command>dir</command> command in DOS.
7736 <literal>*.*</literal> matches all filenames. The <quote>special</quote>
7737 character here is the asterisk which matches any and all characters. We can be
7738 more specific and use <literal>?</literal> to match just individual
7739 characters. So <quote>dir file?.text</quote> would match
7740 <quote>file1.txt</quote>, <quote>file2.txt</quote>, etc. We are pattern
7741 matching, using a similar technique to <quote>regular expressions</quote>!
7745 Regular expressions do essentially the same thing, but are much, much more
7746 powerful. There are many more <quote>special characters</quote> and ways of
7747 building complex patterns however. Let's look at a few of the common ones,
7748 and then some examples:
7753 <emphasis>.</emphasis> - Matches any single character, e.g. <quote>a</quote>,
7754 <quote>A</quote>, <quote>4</quote>, <quote>:</quote>, or <quote>@</quote>.
7760 <emphasis>?</emphasis> - The preceding character or expression is matched ZERO or ONE
7767 <emphasis>+</emphasis> - The preceding character or expression is matched ONE or MORE
7774 <emphasis>*</emphasis> - The preceding character or expression is matched ZERO or MORE
7781 <emphasis>\</emphasis> - The <quote>escape</quote> character denotes that
7782 the following character should be taken literally. This is used where one of the
7783 special characters (e.g. <quote>.</quote>) needs to be taken literally and
7784 not as a special meta-character. Example: <quote>example\.com</quote>, makes
7785 sure the period is recognized only as a period (and not expanded to its
7786 meta-character meaning of any single character).
7792 <emphasis>[ ]</emphasis> - Characters enclosed in brackets will be matched if
7793 any of the enclosed characters are encountered. For instance, <quote>[0-9]</quote>
7794 matches any numeric digit (zero through nine). As an example, we can combine
7795 this with <quote>+</quote> to match any digit one of more times: <quote>[0-9]+</quote>.
7801 <emphasis>( )</emphasis> - parentheses are used to group a sub-expression,
7802 or multiple sub-expressions.
7808 <emphasis>|</emphasis> - The <quote>bar</quote> character works like an
7809 <quote>or</quote> conditional statement. A match is successful if the
7810 sub-expression on either side of <quote>|</quote> matches. As an example:
7811 <quote>/(this|that) example/</quote> uses grouping and the bar character
7812 and would match either <quote>this example</quote> or <quote>that
7813 example</quote>, and nothing else.
7818 These are just some of the ones you are likely to use when matching URLs with
7819 <application>Privoxy</application>, and is a long way from a definitive
7820 list. This is enough to get us started with a few simple examples which may
7821 be more illuminating:
7825 <emphasis><literal>/.*/banners/.*</literal></emphasis> - A simple example
7826 that uses the common combination of <quote>.</quote> and <quote>*</quote> to
7827 denote any character, zero or more times. In other words, any string at all.
7828 So we start with a literal forward slash, then our regular expression pattern
7829 (<quote>.*</quote>) another literal forward slash, the string
7830 <quote>banners</quote>, another forward slash, and lastly another
7831 <quote>.*</quote>. We are building
7832 a directory path here. This will match any file with the path that has a
7833 directory named <quote>banners</quote> in it. The <quote>.*</quote> matches
7834 any characters, and this could conceivably be more forward slashes, so it
7835 might expand into a much longer looking path. For example, this could match:
7836 <quote>/eye/hate/spammers/banners/annoy_me_please.gif</quote>, or just
7837 <quote>/banners/annoying.html</quote>, or almost an infinite number of other
7838 possible combinations, just so it has <quote>banners</quote> in the path
7843 And now something a little more complex:
7847 <emphasis><literal>/.*/adv((er)?ts?|ertis(ing|ements?))?/</literal></emphasis> -
7848 We have several literal forward slashes again (<quote>/</quote>), so we are
7849 building another expression that is a file path statement. We have another
7850 <quote>.*</quote>, so we are matching against any conceivable sub-path, just so
7851 it matches our expression. The only true literal that <emphasis>must
7852 match</emphasis> our pattern is <application>adv</application>, together with
7853 the forward slashes. What comes after the <quote>adv</quote> string is the
7858 Remember the <quote>?</quote> means the preceding expression (either a
7859 literal character or anything grouped with <quote>(...)</quote> in this case)
7860 can exist or not, since this means either zero or one match. So
7861 <quote>((er)?ts?|ertis(ing|ements?))</quote> is optional, as are the
7862 individual sub-expressions: <quote>(er)</quote>,
7863 <quote>(ing|ements?)</quote>, and the <quote>s</quote>. The <quote>|</quote>
7864 means <quote>or</quote>. We have two of those. For instance,
7865 <quote>(ing|ements?)</quote>, can expand to match either <quote>ing</quote>
7866 <emphasis>OR</emphasis> <quote>ements?</quote>. What is being done here, is an
7867 attempt at matching as many variations of <quote>advertisement</quote>, and
7868 similar, as possible. So this would expand to match just <quote>adv</quote>,
7869 or <quote>advert</quote>, or <quote>adverts</quote>, or
7870 <quote>advertising</quote>, or <quote>advertisement</quote>, or
7871 <quote>advertisements</quote>. You get the idea. But it would not match
7872 <quote>advertizements</quote> (with a <quote>z</quote>). We could fix that by
7873 changing our regular expression to:
7874 <quote>/.*/adv((er)?ts?|erti(s|z)(ing|ements?))?/</quote>, which would then match
7879 <emphasis><literal>/.*/advert[0-9]+\.(gif|jpe?g)</literal></emphasis> - Again
7880 another path statement with forward slashes. Anything in the square brackets
7881 <quote>[ ]</quote> can be matched. This is using <quote>0-9</quote> as a
7882 shorthand expression to mean any digit one through nine. It is the same as
7883 saying <quote>0123456789</quote>. So any digit matches. The <quote>+</quote>
7884 means one or more of the preceding expression must be included. The preceding
7885 expression here is what is in the square brackets -- in this case, any digit
7886 one through nine. Then, at the end, we have a grouping: <quote>(gif|jpe?g)</quote>.
7887 This includes a <quote>|</quote>, so this needs to match the expression on
7888 either side of that bar character also. A simple <quote>gif</quote> on one side, and the other
7889 side will in turn match either <quote>jpeg</quote> or <quote>jpg</quote>,
7890 since the <quote>?</quote> means the letter <quote>e</quote> is optional and
7891 can be matched once or not at all. So we are building an expression here to
7892 match image GIF or JPEG type image file. It must include the literal
7893 string <quote>advert</quote>, then one or more digits, and a <quote>.</quote>
7894 (which is now a literal, and not a special character, since it is escaped
7895 with <quote>\</quote>), and lastly either <quote>gif</quote>, or
7896 <quote>jpeg</quote>, or <quote>jpg</quote>. Some possible matches would
7897 include: <quote>//advert1.jpg</quote>,
7898 <quote>/nasty/ads/advert1234.gif</quote>,
7899 <quote>/banners/from/hell/advert99.jpg</quote>. It would not match
7900 <quote>advert1.gif</quote> (no leading slash), or
7901 <quote>/adverts232.jpg</quote> (the expression does not include an
7902 <quote>s</quote>), or <quote>/advert1.jsp</quote> (<quote>jsp</quote> is not
7903 in the expression anywhere).
7907 We are barely scratching the surface of regular expressions here so that you
7908 can understand the default <application>Privoxy</application>
7909 configuration files, and maybe use this knowledge to customize your own
7910 installation. There is much, much more that can be done with regular
7911 expressions. Now that you know enough to get started, you can learn more on
7916 More reading on Perl Compatible Regular expressions:
7917 <ulink url="http://perldoc.perl.org/perlre.html">http://perldoc.perl.org/perlre.html</ulink>
7921 For information on regular expression based substitutions and their applications
7922 in filters, please see the <link linkend="filter-file">filter file tutorial</link>
7927 <!-- ~ End section ~ -->
7930 <!-- ~~~~~ New section ~~~~~ -->
7931 <sect2 id="internal-pages">
7932 <title>Privoxy's Internal Pages</title>
7935 Since <application>Privoxy</application> proxies each requested
7936 web page, it is easy for <application>Privoxy</application> to
7937 trap certain special URLs. In this way, we can talk directly to
7938 <application>Privoxy</application>, and see how it is
7939 configured, see how our rules are being applied, change these
7940 rules and other configuration options, and even turn
7941 <application>Privoxy's</application> filtering off, all with
7946 The URLs listed below are the special ones that allow direct access
7947 to <application>Privoxy</application>. Of course,
7948 <application>Privoxy</application> must be running to access these. If
7949 not, you will get a friendly error message. Internet access is not
7961 <ulink url="http://config.privoxy.org/">http://config.privoxy.org/</ulink>
7965 There is a shortcut: <ulink url="http://p.p/">http://p.p/</ulink> (But it
7966 doesn't provide a fall-back to a real page, in case the request is not
7967 sent through <application>Privoxy</application>)
7973 Show information about the current configuration, including viewing and
7974 editing of actions files:
7978 <ulink url="http://config.privoxy.org/show-status">http://config.privoxy.org/show-status</ulink>
7985 Show the source code version numbers:
7989 <ulink url="http://config.privoxy.org/show-version">http://config.privoxy.org/show-version</ulink>
7996 Show the browser's request headers:
8000 <ulink url="http://config.privoxy.org/show-request">http://config.privoxy.org/show-request</ulink>
8007 Show which actions apply to a URL and why:
8011 <ulink url="http://config.privoxy.org/show-url-info">http://config.privoxy.org/show-url-info</ulink>
8018 Toggle Privoxy on or off. This feature can be turned off/on in the main
8019 <filename>config</filename> file. When toggled <quote>off</quote>, <quote>Privoxy</quote>
8020 continues to run, but only as a pass-through proxy, with no actions taking
8025 <ulink url="http://config.privoxy.org/toggle">http://config.privoxy.org/toggle</ulink>
8029 Short cuts. Turn off, then on:
8033 <ulink url="http://config.privoxy.org/toggle?set=disable">http://config.privoxy.org/toggle?set=disable</ulink>
8038 <ulink url="http://config.privoxy.org/toggle?set=enable">http://config.privoxy.org/toggle?set=enable</ulink>
8048 <!-- ~~~~~ New section ~~~~~ -->
8050 <title>Chain of Events</title>
8052 Let's take a quick look at how some of <application>Privoxy's</application>
8053 core features are triggered, and the ensuing sequence of events when a web
8054 page is requested by your browser:
8060 First, your web browser requests a web page. The browser knows to send
8061 the request to <application>Privoxy</application>, which will in turn,
8062 relay the request to the remote web server after passing the following
8068 <application>Privoxy</application> traps any request for its own internal CGI
8069 pages (e.g <ulink url="http://p.p/">http://p.p/</ulink>) and sends the CGI page back to the browser.
8074 Next, <application>Privoxy</application> checks to see if the URL
8076 linkend="BLOCK"><quote>+block</quote></link> patterns. If
8077 so, the URL is then blocked, and the remote web server will not be contacted.
8078 <link linkend="HANDLE-AS-IMAGE"><quote>+handle-as-image</quote></link>
8080 <link linkend="HANDLE-AS-EMPTY-DOCUMENT"><quote>+handle-as-empty-document</quote></link>
8081 are then checked, and if there is no match, an
8082 HTML <quote>BLOCKED</quote> page is sent back to the browser. Otherwise, if
8083 it does match, an image is returned for the former, and an empty text
8084 document for the latter. The type of image would depend on the setting of
8085 <link linkend="SET-IMAGE-BLOCKER"><quote>+set-image-blocker</quote></link>
8086 (blank, checkerboard pattern, or an HTTP redirect to an image elsewhere).
8091 Untrusted URLs are blocked. If URLs are being added to the
8092 <filename>trust</filename> file, then that is done.
8097 If the URL pattern matches the <link
8098 linkend="FAST-REDIRECTS"><quote>+fast-redirects</quote></link> action,
8099 it is then processed. Unwanted parts of the requested URL are stripped.
8104 Now the rest of the client browser's request headers are processed. If any
8105 of these match any of the relevant actions (e.g. <link
8106 linkend="HIDE-USER-AGENT"><quote>+hide-user-agent</quote></link>,
8107 etc.), headers are suppressed or forged as determined by these actions and
8113 Now the web server starts sending its response back (i.e. typically a web
8119 First, the server headers are read and processed to determine, among other
8120 things, the MIME type (document type) and encoding. The headers are then
8121 filtered as determined by the
8122 <link linkend="CRUNCH-INCOMING-COOKIES"><quote>+crunch-incoming-cookies</quote></link>,
8123 <link linkend="SESSION-COOKIES-ONLY"><quote>+session-cookies-only</quote></link>,
8124 and <link linkend="DOWNGRADE-HTTP-VERSION"><quote>+downgrade-http-version</quote></link>
8130 If any <link linkend="FILTER"><quote>+filter</quote></link> action
8132 linkend="DEANIMATE-GIFS"><quote>+deanimate-gifs</quote></link>
8133 action applies (and the document type fits the action), the rest of the page is
8134 read into memory (up to a configurable limit). Then the filter rules (from
8135 <filename>default.filter</filename> and any other filter files) are
8136 processed against the buffered content. Filters are applied in the order
8137 they are specified in one of the filter files. Animated GIFs, if present,
8138 are reduced to either the first or last frame, depending on the action
8139 setting.The entire page, which is now filtered, is then sent by
8140 <application>Privoxy</application> back to your browser.
8143 If neither a <link linkend="FILTER"><quote>+filter</quote></link> action
8145 linkend="DEANIMATE-GIFS"><quote>+deanimate-gifs</quote></link>
8146 matches, then <application>Privoxy</application> passes the raw data through
8147 to the client browser as it becomes available.
8152 As the browser receives the now (possibly filtered) page content, it
8153 reads and then requests any URLs that may be embedded within the page
8154 source, e.g. ad images, stylesheets, JavaScript, other HTML documents (e.g.
8155 frames), sounds, etc. For each of these objects, the browser issues a
8156 separate request (this is easily viewable in <application>Privoxy's</application>
8157 logs). And each such request is in turn processed just as above. Note that a
8158 complex web page will have many, many such embedded URLs. If these
8159 secondary requests are to a different server, then quite possibly a very
8160 differing set of actions is triggered.
8167 NOTE: This is somewhat of a simplistic overview of what happens with each URL
8168 request. For the sake of brevity and simplicity, we have focused on
8169 <application>Privoxy's</application> core features only.
8175 <!-- ~~~~~ New section ~~~~~ -->
8176 <sect2 id="actionsanat">
8177 <title>Troubleshooting: Anatomy of an Action</title>
8180 The way <application>Privoxy</application> applies
8181 <link linkend="ACTIONS">actions</link> and <link linkend="FILTER">filters</link>
8182 to any given URL can be complex, and not always so
8183 easy to understand what is happening. And sometimes we need to be able to
8184 <emphasis>see</emphasis> just what <application>Privoxy</application> is
8185 doing. Especially, if something <application>Privoxy</application> is doing
8186 is causing us a problem inadvertently. It can be a little daunting to look at
8187 the actions and filters files themselves, since they tend to be filled with
8188 <link linkend="regex">regular expressions</link> whose consequences are not
8193 One quick test to see if <application>Privoxy</application> is causing a problem
8194 or not, is to disable it temporarily. This should be the first troubleshooting
8195 step (be sure to flush caches afterward!). Looking at the
8196 logs is a good idea too. (Note that both the toggle feature and logging are
8197 enabled via <filename>config</filename> file settings, and may need to be
8198 turned <quote>on</quote>.)
8201 Another easy troubleshooting step to try is if you have done any
8202 customization of your installation, revert back to the installed
8203 defaults and see if that helps. There are times the developers get complaints
8204 about one thing or another, and the problem is more related to a customized
8205 configuration issue.
8209 <application>Privoxy</application> also provides the
8210 <ulink url="http://config.privoxy.org/show-url-info">http://config.privoxy.org/show-url-info</ulink>
8211 page that can show us very specifically how <application>actions</application>
8212 are being applied to any given URL. This is a big help for troubleshooting.
8216 First, enter one URL (or partial URL) at the prompt, and then
8217 <application>Privoxy</application> will tell us
8218 how the current configuration will handle it. This will not
8219 help with filtering effects (i.e. the <link
8220 linkend="FILTER"><quote>+filter</quote></link> action) from
8221 one of the filter files since this is handled very
8222 differently and not so easy to trap! It also will not tell you about any other
8223 URLs that may be embedded within the URL you are testing. For instance, images
8224 such as ads are expressed as URLs within the raw page source of HTML pages. So
8225 you will only get info for the actual URL that is pasted into the prompt area
8226 -- not any sub-URLs. If you want to know about embedded URLs like ads, you
8227 will have to dig those out of the HTML source. Use your browser's <quote>View
8228 Page Source</quote> option for this. Or right click on the ad, and grab the
8233 Let's try an example, <ulink url="http://google.com">google.com</ulink>,
8234 and look at it one section at a time in a sample configuration (your real
8235 configuration may vary):
8239 Matches for http://www.google.com:
8241 In file: default.action <guibutton>[ View ]</guibutton> <guibutton>[ Edit ]</guibutton>
8243 {+change-x-forwarded-for{block}
8244 +deanimate-gifs {last}
8245 +fast-redirects {check-decoded-url}
8246 +filter {refresh-tags}
8247 +filter {img-reorder}
8248 +filter {banners-by-size}
8250 +filter {jumping-windows}
8251 +filter {ie-exploits}
8252 +hide-from-header {block}
8253 +hide-referrer {forge}
8254 +session-cookies-only
8255 +set-image-blocker {pattern}
8258 { -session-cookies-only }
8264 In file: user.action <guibutton>[ View ]</guibutton> <guibutton>[ Edit ]</guibutton>
8265 (no matches in this file)
8269 This is telling us how we have defined our
8270 <link linkend="ACTIONS"><quote>actions</quote></link>, and
8271 which ones match for our test case, <quote>google.com</quote>.
8272 Displayed is all the actions that are available to us. Remember,
8273 the <literal>+</literal> sign denotes <quote>on</quote>. <literal>-</literal>
8274 denotes <quote>off</quote>. So some are <quote>on</quote> here, but many
8275 are <quote>off</quote>. Each example we try may provide a slightly different
8276 end result, depending on our configuration directives.
8280 is for our <filename>default.action</filename> file. The large, multi-line
8281 listing, is how the actions are set to match for all URLs, i.e. our default
8282 settings. If you look at your <quote>actions</quote> file, this would be the
8283 section just below the <quote>aliases</quote> section near the top. This
8284 will apply to all URLs as signified by the single forward slash at the end
8285 of the listing -- <quote> / </quote>.
8289 But we have defined additional actions that would be exceptions to these general
8290 rules, and then we list specific URLs (or patterns) that these exceptions
8291 would apply to. Last match wins. Just below this then are two explicit
8292 matches for <quote>.google.com</quote>. The first is negating our previous
8293 cookie setting, which was for <link
8294 linkend="SESSION-COOKIES-ONLY"><quote>+session-cookies-only</quote></link>
8295 (i.e. not persistent). So we will allow persistent cookies for google, at
8296 least that is how it is in this example. The second turns
8297 <emphasis>off</emphasis> any <link
8298 linkend="FAST-REDIRECTS"><quote>+fast-redirects</quote></link>
8299 action, allowing this to take place unmolested. Note that there is a leading
8300 dot here -- <quote>.google.com</quote>. This will match any hosts and
8301 sub-domains, in the google.com domain also, such as
8302 <quote>www.google.com</quote> or <quote>mail.google.com</quote>. But it would not
8303 match <quote>www.google.de</quote>! So, apparently, we have these two actions
8304 defined as exceptions to the general rules at the top somewhere in the lower
8305 part of our <filename>default.action</filename> file, and
8306 <quote>google.com</quote> is referenced somewhere in these latter sections.
8310 Then, for our <filename>user.action</filename> file, we again have no hits.
8311 So there is nothing google-specific that we might have added to our own, local
8312 configuration. If there was, those actions would over-rule any actions from
8313 previously processed files, such as <filename>default.action</filename>.
8314 <filename>user.action</filename> typically has the last word. This is the
8315 best place to put hard and fast exceptions,
8319 And finally we pull it all together in the bottom section and summarize how
8320 <application>Privoxy</application> is applying all its <quote>actions</quote>
8321 to <quote>google.com</quote>:
8329 +change-x-forwarded-for{block}
8330 -client-header-filter{hide-tor-exit-notation}
8331 -content-type-overwrite
8332 -crunch-client-header
8333 -crunch-if-none-match
8334 -crunch-incoming-cookies
8335 -crunch-outgoing-cookies
8336 -crunch-server-header
8337 +deanimate-gifs {last}
8338 -downgrade-http-version
8341 -filter {content-cookies}
8342 -filter {all-popups}
8343 -filter {banners-by-link}
8344 -filter {tiny-textforms}
8345 -filter {frameset-borders}
8346 -filter {demoronizer}
8347 -filter {shockwave-flash}
8348 -filter {quicktime-kioskmode}
8350 -filter {crude-parental}
8351 -filter {site-specifics}
8352 -filter {js-annoyances}
8353 -filter {html-annoyances}
8354 +filter {refresh-tags}
8355 -filter {unsolicited-popups}
8356 +filter {img-reorder}
8357 +filter {banners-by-size}
8359 +filter {jumping-windows}
8360 +filter {ie-exploits}
8367 -handle-as-empty-document
8369 -hide-accept-language
8370 -hide-content-disposition
8371 +hide-from-header {block}
8372 -hide-if-modified-since
8373 +hide-referrer {forge}
8376 -overwrite-last-modified
8377 -prevent-compression
8379 -server-header-filter{xml-to-html}
8380 -server-header-filter{html-to-xml}
8381 -session-cookies-only
8382 +set-image-blocker {pattern}
8386 Notice the only difference here to the previous listing, is to
8387 <quote>fast-redirects</quote> and <quote>session-cookies-only</quote>,
8388 which are activated specifically for this site in our configuration,
8389 and thus show in the <quote>Final Results</quote>.
8393 Now another example, <quote>ad.doubleclick.net</quote>:
8397 { +block{Domains starts with "ad"} }
8400 { +block{Domain contains "ad"} }
8403 { +block{Doubleclick banner server} +handle-as-image }
8404 .[a-vx-z]*.doubleclick.net
8408 We'll just show the interesting part here - the explicit matches. It is
8409 matched three different times. Two <quote>+block{}</quote> sections,
8410 and a <quote>+block{} +handle-as-image</quote>,
8411 which is the expanded form of one of our aliases that had been defined as:
8412 <quote>+block-as-image</quote>. (<link
8413 linkend="ALIASES"><quote>Aliases</quote></link> are defined in
8414 the first section of the actions file and typically used to combine more
8419 Any one of these would have done the trick and blocked this as an unwanted
8420 image. This is unnecessarily redundant since the last case effectively
8421 would also cover the first. No point in taking chances with these guys
8422 though ;-) Note that if you want an ad or obnoxious
8423 URL to be invisible, it should be defined as <quote>ad.doubleclick.net</quote>
8424 is done here -- as both a <link
8425 linkend="BLOCK"><quote>+block{}</quote></link>
8426 <emphasis>and</emphasis> an
8427 <link linkend="HANDLE-AS-IMAGE"><quote>+handle-as-image</quote></link>.
8428 The custom alias <quote><literal>+block-as-image</literal></quote> just
8429 simplifies the process and make it more readable.
8433 One last example. Let's try <quote>http://www.example.net/adsl/HOWTO/</quote>.
8434 This one is giving us problems. We are getting a blank page. Hmmm ...
8438 Matches for http://www.example.net/adsl/HOWTO/:
8440 In file: default.action <guibutton>[ View ]</guibutton> <guibutton>[ Edit ]</guibutton>
8444 +change-x-forwarded-for{block}
8445 -client-header-filter{hide-tor-exit-notation}
8446 -content-type-overwrite
8447 -crunch-client-header
8448 -crunch-if-none-match
8449 -crunch-incoming-cookies
8450 -crunch-outgoing-cookies
8451 -crunch-server-header
8453 -downgrade-http-version
8454 +fast-redirects {check-decoded-url}
8456 -filter {content-cookies}
8457 -filter {all-popups}
8458 -filter {banners-by-link}
8459 -filter {tiny-textforms}
8460 -filter {frameset-borders}
8461 -filter {demoronizer}
8462 -filter {shockwave-flash}
8463 -filter {quicktime-kioskmode}
8465 -filter {crude-parental}
8466 -filter {site-specifics}
8467 -filter {js-annoyances}
8468 -filter {html-annoyances}
8469 +filter {refresh-tags}
8470 -filter {unsolicited-popups}
8471 +filter {img-reorder}
8472 +filter {banners-by-size}
8474 +filter {jumping-windows}
8475 +filter {ie-exploits}
8482 -handle-as-empty-document
8484 -hide-accept-language
8485 -hide-content-disposition
8486 +hide-from-header{block}
8487 +hide-referer{forge}
8489 -overwrite-last-modified
8490 +prevent-compression
8492 -server-header-filter{xml-to-html}
8493 -server-header-filter{html-to-xml}
8494 +session-cookies-only
8495 +set-image-blocker{blank} }
8498 { +block{Path contains "ads".} +handle-as-image }
8503 Ooops, the <quote>/adsl/</quote> is matching <quote>/ads</quote> in our
8504 configuration! But we did not want this at all! Now we see why we get the
8505 blank page. It is actually triggering two different actions here, and
8506 the effects are aggregated so that the URL is blocked, and &my-app; is told
8507 to treat the block as if it were an image. But this is, of course, all wrong.
8508 We could now add a new action below this (or better in our own
8509 <filename>user.action</filename> file) that explicitly
8510 <emphasis>un</emphasis> blocks (
8511 <link linkend="BLOCK"><quote>{-block}</quote></link>) paths with
8512 <quote>adsl</quote> in them (remember, last match in the configuration
8513 wins). There are various ways to handle such exceptions. Example:
8522 Now the page displays ;-)
8523 Remember to flush your browser's caches when making these kinds of changes to
8524 your configuration to insure that you get a freshly delivered page! Or, try
8525 using <literal>Shift+Reload</literal>.
8529 But now what about a situation where we get no explicit matches like
8534 { +block{Path starts with "ads".} +handle-as-image }
8539 That actually was very helpful and pointed us quickly to where the problem
8540 was. If you don't get this kind of match, then it means one of the default
8541 rules in the first section of <filename>default.action</filename> is causing
8542 the problem. This would require some guesswork, and maybe a little trial and
8543 error to isolate the offending rule. One likely cause would be one of the
8544 <link linkend="FILTER"><quote>+filter</quote></link> actions.
8545 These tend to be harder to troubleshoot.
8546 Try adding the URL for the site to one of aliases that turn off
8547 <link linkend="FILTER"><quote>+filter</quote></link>:
8553 .worldpay.com # for quietpc.com
8560 <quote><literal>{ shop }</literal></quote> is an <quote>alias</quote> that expands to
8561 <quote><literal>{ -filter -session-cookies-only }</literal></quote>.
8562 Or you could do your own exception to negate filtering:
8567 # Disable ALL filter actions for sites in this section
8574 This would turn off all filtering for these sites. This is best
8575 put in <filename>user.action</filename>, for local site
8576 exceptions. Note that when a simple domain pattern is used by itself (without
8577 the subsequent path portion), all sub-pages within that domain are included
8578 automatically in the scope of the action.
8582 Images that are inexplicably being blocked, may well be hitting the
8583 <link linkend="FILTER-BANNERS-BY-SIZE"><quote>+filter{banners-by-size}</quote></link>
8585 that images of certain sizes are ad banners (works well
8586 <emphasis>most of the time</emphasis> since these tend to be standardized).
8590 <quote><literal>{ fragile }</literal></quote> is an alias that disables most
8591 actions that are the most likely to cause trouble. This can be used as a
8592 last resort for problem sites.
8597 # Handle with care: easy to break
8599 mybank.example.com</screen>
8603 <emphasis>Remember to flush caches!</emphasis> Note that the
8604 <literal>mail.google</literal> reference lacks the TLD portion (e.g.
8605 <quote>.com</quote>). This will effectively match any TLD with
8606 <literal>google</literal> in it, such as <literal>mail.google.de.</literal>,
8610 If this still does not work, you will have to go through the remaining
8611 actions one by one to find which one(s) is causing the problem.
8620 This program is free software; you can redistribute it
8621 and/or modify it under the terms of the GNU General
8622 Public License as published by the Free Software
8623 Foundation; either version 2 of the License, or (at
8624 your option) any later version.
8626 This program is distributed in the hope that it will
8627 be useful, but WITHOUT ANY WARRANTY; without even the
8628 implied warranty of MERCHANTABILITY or FITNESS FOR A
8629 PARTICULAR PURPOSE. See the GNU General Public
8630 License for more details.
8632 The GNU General Public License should be included with
8633 this file. If not, you can view it at
8634 http://www.gnu.org/copyleft/gpl.html
8635 or write to the Free Software Foundation, Inc.,
8636 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,