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6 <!entity seealso SYSTEM "seealso.sgml">
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12 <!entity GPLv2 SYSTEM "../../LICENSE">
13 <!entity p-authors SYSTEM "p-authors.sgml">
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15 <!entity changelog SYSTEM "changelog.sgml">
16 <!entity p-version "3.0.28">
17 <!entity p-status "stable">
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19 <!entity % p-not-stable "IGNORE">
20 <!entity % p-stable "INCLUDE">
21 <!entity % p-text "IGNORE"> <!-- define we are not a text only doc -->
22 <!entity % p-doc "INCLUDE"> <!-- and we are a formal doc -->
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26 <!entity % p-supp-userman "IGNORE"> <!-- Omit some from supported.sgml -->
27 <!entity my-copy "©"> <!-- kludge for docbook2man -->
28 <!entity % draft "IGNORE"> <!-- WIP stuff -->
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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 <ulink url="https://www.privoxy.org/gitweb/?p=privoxy.git;a=summary">git sources</ulink>).
125 And there <emphasis>may be</emphasis> bugs, though hopefully
130 <!-- ~~~~~ New section ~~~~~ -->
131 <sect2 id="features"><title>Features</title>
133 In addition to the core
134 features of ad blocking and
135 <ulink url="http://en.wikipedia.org/wiki/Browser_cookie">cookie</ulink> management,
136 <application>Privoxy</application> provides many supplemental
137 features<![%p-not-stable;[, some of them currently under development]]>,
138 that give the end-user more control, more privacy and more freedom:
140 <!-- Include newfeatures.sgml boilerplate here: -->
142 <!-- end boilerplate -->
147 <!-- ~ End section ~ -->
150 <!-- ~~~~~ New section ~~~~~ -->
151 <sect1 id="installation"><title>Installation</title>
154 <application>Privoxy</application> is available both in convenient pre-compiled
155 packages for a wide range of operating systems, and as raw source code.
156 For most users, we recommend using the packages, which can be downloaded from our
157 <ulink url="https://sourceforge.net/projects/ijbswa/">Privoxy Project
163 On some platforms, the installer may remove previously installed versions, if
164 found. (See below for your platform). In any case <emphasis>be sure to backup
165 your old configuration if it is valuable to you.</emphasis> See the <link
166 linkend="upgradersnote">note to upgraders</link> section below.
169 <!-- ~~~~~ New section ~~~~~ -->
170 <sect2 id="installation-packages"><title>Binary Packages</title>
172 How to install the binary packages depends on your operating system:
175 <!-- XXX: The installation sections should be sorted -->
177 <!-- ~~~~~ New section ~~~~~ -->
178 <sect3 id="installation-deb"><title>Debian and Ubuntu</title>
180 DEBs can be installed with <literal>apt-get install privoxy</literal>,
181 and will use <filename>/etc/privoxy</filename> for the location of
186 <!-- ~~~~~ New section ~~~~~ -->
187 <sect3 id="installation-pack-win"><title>Windows</title>
190 Just double-click the installer, which will guide you through
191 the installation process. You will find the configuration files
192 in the same directory as you installed <application>Privoxy</application> in.
195 Version 3.0.5 beta introduced full <application>Windows</application> service
196 functionality. On Windows only, the <application>Privoxy</application>
197 program has two new command line arguments to install and uninstall
198 <application>Privoxy</application> as a <emphasis>service</emphasis>.
202 <term>Arguments:</term>
205 <replaceable class="parameter">--install</replaceable>[:<replaceable class="parameter">service_name</replaceable>]
208 <replaceable class="parameter">--uninstall</replaceable>[:<replaceable class="parameter">service_name</replaceable>]
214 After invoking <application>Privoxy</application> with
215 <command>--install</command>, you will need to bring up the
216 <application>Windows</application> service console to assign the user you
217 want <application>Privoxy</application> to run under, and whether or not you
218 want it to run whenever the system starts. You can start the
219 <application>Windows</application> services console with the following
220 command: <command>services.msc</command>. If you do not take the manual step
221 of modifying <application>Privoxy's</application> service settings, it will
222 not start. Note too that you will need to give Privoxy a user account that
223 actually exists, or it will not be permitted to
224 write to its log and configuration files.
229 <!-- ~~~~~ New section ~~~~~ -->
230 <sect3 id="installation-os2"><title>OS/2</title>
233 First, make sure that no previous installations of
234 <application>Junkbuster</application> and / or
235 <application>Privoxy</application> are left on your
236 system. Check that no <application>Junkbuster</application>
237 or <application>Privoxy</application> objects are in
242 Then, just double-click the WarpIN self-installing archive, which will
243 guide you through the installation process. A shadow of the
244 <application>Privoxy</application> executable will be placed in your
245 startup folder so it will start automatically whenever OS/2 starts.
249 The directory you choose to install <application>Privoxy</application>
250 into will contain all of the configuration files.
254 <!-- ~~~~~ New section ~~~~~ -->
255 <sect3 id="installation-mac"><title>Mac OS X</title>
257 Installation instructions for the OS X platform depend upon whether
258 you downloaded a ready-built installation package (.pkg or .mpkg) or have
259 downloaded the source code.
262 <sect3 renderas="sect4" id="OS-X-install-from-package">
263 <title>Installation from ready-built package</title>
265 The downloaded file will either be a .pkg (for OS X 10.5 upwards) or a bzipped
266 .mpkg file (for OS X 10.4). The former can be double-clicked as is and the
267 installation will start; double-clicking the latter will unzip the .mpkg file
268 which can then be double-clicked to commence the installation.
271 The privoxy service will automatically start after a successful installation
272 (and thereafter every time your computer starts up) however you will need to
273 configure your web browser(s) to use it. To do so, configure them to use a
274 proxy for HTTP and HTTPS at the address 127.0.0.1:8118.
277 To prevent the privoxy service from automatically starting when your computer
278 starts up, remove or rename the file <literal>/Library/LaunchDaemons/org.ijbswa.privoxy.plist</literal>
279 (on OS X 10.5 and higher) or the folder named
280 <literal>/Library/StartupItems/Privoxy</literal> (on OS X 10.4 'Tiger').
283 To manually start or stop the privoxy service, use the scripts startPrivoxy.sh
284 and stopPrivoxy.sh supplied in /Applications/Privoxy. They must be run from an
285 administrator account, using sudo.
288 To uninstall, run /Applications/Privoxy/uninstall.command as sudo from an
289 administrator account.
292 <sect3 renderas="sect4" id="OS-X-install-from-source">
293 <title>Installation from source</title>
295 To build and install the Privoxy source code on OS X you will need to obtain
296 the macsetup module from the Privoxy Sourceforge CVS repository (refer to
297 Sourceforge help for details of how to set up a CVS client to have read-only
298 access to the repository). This module contains scripts that leverage the usual
299 open-source tools (available as part of Apple's free of charge Xcode
300 distribution or via the usual open-source software package managers for OS X
301 (MacPorts, Homebrew, Fink etc.) to build and then install the privoxy binary
302 and associated files. The macsetup module's README file contains complete
303 instructions for its use.
306 The privoxy service will automatically start after a successful installation
307 (and thereafter every time your computer starts up) however you will need to
308 configure your web browser(s) to use it. To do so, configure them to use a
309 proxy for HTTP and HTTPS at the address 127.0.0.1:8118.
312 To prevent the privoxy service from automatically starting when your computer
313 starts up, remove or rename the file <literal>/Library/LaunchDaemons/org.ijbswa.privoxy.plist</literal>
314 (on OS X 10.5 and higher) or the folder named
315 <literal>/Library/StartupItems/Privoxy</literal> (on OS X 10.4 'Tiger').
318 To manually start or stop the privoxy service, use the Privoxy Utility
319 for Mac OS X (also part of the macsetup module). This application can start
320 and stop the privoxy service and display its log and configuration files.
323 To uninstall, run the macsetup module's uninstall.sh as sudo from an
324 administrator account.
328 <!-- ~~~~~ New section ~~~~~ -->
329 <sect3 id="installation-freebsd"><title>FreeBSD</title>
332 Privoxy is part of FreeBSD's Ports Collection, you can build and install
333 it with <literal>cd /usr/ports/www/privoxy; make install clean</literal>.
339 <!-- ~~~~~ New section ~~~~~ -->
340 <sect2 id="installation-source"><title>Building from Source</title>
343 The most convenient way to obtain the <application>Privoxy</application> source
344 code is to download the source tarball from our
345 <ulink url="https://sourceforge.net/projects/ijbswa/files/Sources/">
346 project download page</ulink>,
347 or you can get the up-to-the-minute, possibly unstable, development version from
348 <ulink url="https://www.privoxy.org/">https://www.privoxy.org/</ulink>.
351 <!-- include buildsource.sgml boilerplate: -->
353 <!-- end boilerplate -->
356 <sect3 id="WINBUILD-CYGWIN"><title>Windows</title>
358 <sect4 id="WINBUILD-SETUP"><title>Setup</title>
360 Install the Cygwin utilities needed to build <application>Privoxy</application>.
361 If you have a 64 bit CPU (which most people do by now), get the
362 Cygwin setup-x86_64.exe program <ulink url="https://cygwin.com/setup-x86_64.exe">here</ulink>
363 (the .sig file is <ulink url="https://cygwin.com/setup-x86_64.exe.sig">here</ulink>).
366 Run the setup program and from View / Category select:
378 mingw64-i686-gcc-core
383 libxslt: GNOME XSLT library (runtime)
399 If you haven't already downloaded the Privoxy source code, get it now:
404 git clone https://www.privoxy.org/git/privoxy.git
408 Get the source code (.zip or .tar.gz) for tidy from
409 <ulink url="https://github.com/htacg/tidy-html5/releases">
410 https://github.com/htacg/tidy-html5/releases</ulink>,
411 unzip into <root-dir> and build the software:
415 cd tidy-html5-x.y.z/build/cmake
416 cmake ../.. -DCMAKE_BUILD_TYPE=Release -DBUILD_SHARED_LIB:BOOL=OFF -DCMAKE_INSTALL_PREFIX=/usr/local
421 If you want to be able to make a Windows release package, get the NSIS .zip file from
422 <!-- FIXME: which version(s) are known to work? -->
423 <ulink url="https://sourceforge.net/projects/nsis/files/NSIS%203/">
424 https://sourceforge.net/projects/nsis/files/NSIS%203/</ulink>
425 and extract the NSIS directory to <literal>privoxy/windows</literal>.
426 Then edit the windows/GNUmakefile to set the location of the NSIS executable - eg:
430 MAKENSIS = ./nsis/makensis.exe
435 <sect4 id="WINBUILD-BUILD"><title>Build</title>
438 To build just the Privoxy executable and not the whole installation package, do:
441 cd <root-dir>/privoxy
442 ./windows/MYconfigure && make
446 Privoxy uses the <ulink url="https://en.wikipedia.org/wiki/GNU_build_system">GNU Autotools</ulink>
447 for building software, so the process is:
450 $ autoheader # creates config.h.in
451 $ autoconf # uses config.h.in to create the configure shell script
452 $ ./configure [options] # creates GNUmakefile
453 $ make [options] # builds the program
457 The usual <literal>configure</literal> options for building a native Windows application under cygwin are
460 <literallayout class="Monospaced">
461 --host=i686-w64-mingw32
464 --enable-static-linking
466 --disable-dynamic-pcre
470 You can set the <literal>CFLAGS</literal> and <literal>LDFLAGS</literal> envars before
471 running <literal>configure</literal> to set compiler and linker flags. For example:
475 $ export CFLAGS="-O2" # set gcc optimization level
476 $ export LDFLAGS="-Wl,--nxcompat" # Enable DEP
477 $ ./configure --host=i686-w64-mingw32 --enable-mingw32 --enable-zlib \
478 > --enable-static-linking --disable-pthread --disable-dynamic-pcre
479 $ make # build Privoxy
483 See the <ulink url="../developer-manual/newrelease.html#NEWRELEASE-WINDOWS">Developer's Manual</ulink>
484 for building a Windows release package.
492 <!-- ~~~~~ New section ~~~~~ -->
493 <sect2 id="installation-keepupdated"><title>Keeping your Installation Up-to-Date</title>
496 If you wish to receive an email notification whenever we release updates of
497 <application>Privoxy</application> or the actions file, <ulink
498 url="https://lists.privoxy.org/mailman/listinfo/privoxy-announce">subscribe
499 to our announce mailing list</ulink>, privoxy-announce@lists.privoxy.org.
503 In order not to lose your personal changes and adjustments when updating
504 to the latest <literal>default.action</literal> file we <emphasis>strongly
505 recommend</emphasis> that you use <literal>user.action</literal> and
506 <literal>user.filter</literal> for your local
507 customizations of <application>Privoxy</application>. See the <link
508 linkend="actions-file">Chapter on actions files</link> for details.
516 <!-- ~ End section ~ -->
518 <!-- ~~~~~ New section ~~~~~ -->
519 <sect1 id="whatsnew">
520 <title>What's New in this Release</title>
524 <!-- ~~~~~ New section ~~~~~ -->
526 <sect2 id="upgradersnote">
527 <title>Note to Upgraders</title>
530 A quick list of things to be aware of before upgrading from earlier
531 versions of <application>Privoxy</application>:
538 The recommended way to upgrade &my-app; is to backup your old
539 configuration files, install the new ones, verify that &my-app;
540 is working correctly and finally merge back your changes using
541 <application>diff</application> and maybe <application>patch</application>.
544 There are a number of new features in each &my-app; release and
545 most of them have to be explicitly enabled in the configuration
546 files. Old configuration files obviously don't do that and due
547 to syntax changes using old configuration files with a new
548 &my-app; isn't always possible anyway.
553 Note that some installers remove earlier versions completely,
554 including configuration files, therefore you should really save
555 any important configuration files!
560 On the other hand, other installers don't overwrite existing configuration
561 files, thinking you will want to do that yourself.
566 In the default configuration only fatal errors are logged now.
567 You can change that in the <link linkend="DEBUG">debug section</link>
568 of the configuration file. You may also want to enable more verbose
569 logging until you verified that the new &my-app; version is working
576 Three other config file settings are now off by default:
577 <link linkend="enable-remote-toggle">enable-remote-toggle</link>,
578 <link linkend="enable-remote-http-toggle">enable-remote-http-toggle</link>,
579 and <link linkend="enable-edit-actions">enable-edit-actions</link>.
580 If you use or want these, you will need to explicitly enable them, and
581 be aware of the security issues involved.
588 What constitutes a <quote>default</quote> configuration has changed,
589 and you may want to review which actions are <quote>on</quote> by
590 default. This is primarily a matter of emphasis, but some features
591 you may have been used to, may now be <quote>off</quote> by default.
592 There are also a number of new actions and filters you may want to
593 consider, most of which are not fully incorporated into the default
594 settings as yet (see above).
601 The default actions setting is now <literal>Cautious</literal>. Previous
602 releases had a default setting of <literal>Medium</literal>. Experienced
603 users may want to adjust this, as it is fairly conservative by &my-app;
604 standards and past practices. See <ulink
605 url="http://config.privoxy.org/edit-actions-list?f=default">
606 http://config.privoxy.org/edit-actions-list?f=default</ulink>. New users
607 should try the default settings for a while before turning up the volume.
613 The default setting has filtering turned <emphasis>off</emphasis>, which
614 subsequently means that compression is <emphasis>on</emphasis>. Remember
615 that filtering does not work on compressed pages, so if you use, or want to
616 use, filtering, you will need to force compression off. Example:
619 { +<link linkend="filter">filter</link>{google} +<link linkend="prevent-compression">prevent-compression</link> }
622 Or if you use a number of filters, or filter many sites, you may just want
623 to turn off compression for all sites in
624 <filename>default.action</filename> (or
625 <filename>user.action</filename>).
632 Also, <link linkend="SESSION-COOKIES-ONLY">session-cookies-only</link> is
633 off by default now. If you've liked this feature in the past, you may want
634 to turn it back on in <filename>user.action</filename> now.
641 Some installers may not automatically start
642 <application>Privoxy</application> after installation.
652 <!-- ~~~~~ New section ~~~~~ -->
653 <sect1 id="quickstart"><title>Quickstart to Using Privoxy</title>
659 Install <application>Privoxy</application>. See the <link
660 linkend="installation">Installation Section</link> below for platform specific
667 Advanced users and those who want to offer <application>Privoxy</application>
668 service to more than just their local machine should check the <link
669 linkend="config">main config file</link>, especially the <link
670 linkend="access-control">security-relevant</link> options. These are
677 Start <application>Privoxy</application>, if the installation program has
678 not done this already (may vary according to platform). See the section
679 <link linkend="startup">Starting <application>Privoxy</application></link>.
685 Set your browser to use <application>Privoxy</application> as HTTP and
686 HTTPS (SSL) <ulink url="http://en.wikipedia.org/wiki/Proxy_server">proxy</ulink>
687 by setting the proxy configuration for address of
688 <literal>127.0.0.1</literal> and port <literal>8118</literal>.
689 <emphasis>DO NOT</emphasis> activate proxying for <literal>FTP</literal> or
690 any protocols besides HTTP and HTTPS (SSL) unless you intend to prevent your
691 browser from using these protocols.
697 Flush your browser's disk and memory caches, to remove any cached ad images.
698 If using <application>Privoxy</application> to manage
699 <ulink url="http://en.wikipedia.org/wiki/Browser_cookie">cookies</ulink>,
700 you should remove any currently stored cookies too.
706 A default installation should provide a reasonable starting point for
707 most. There will undoubtedly be occasions where you will want to adjust the
708 configuration, but that can be dealt with as the need arises. Little
709 to no initial configuration is required in most cases, you may want
711 <ulink url="config.html#ENABLE-EDIT-ACTIONS">web-based action editor</ulink> though.
712 Be sure to read the warnings first.
715 See the <link linkend="configuration">Configuration section</link> for more
716 configuration options, and how to customize your installation.
717 You might also want to look at the <link
718 linkend="quickstart-ad-blocking">next section</link> for a quick
719 introduction to how <application>Privoxy</application> blocks ads and
726 If you experience ads that slip through, innocent images that are
727 blocked, or otherwise feel the need to fine-tune
728 <application>Privoxy's</application> behavior, take a look at the <link
729 linkend="actions-file">actions files</link>. As a quick start, you might
730 find the <link linkend="act-examples">richly commented examples</link>
731 helpful. You can also view and edit the actions files through the <ulink
732 url="http://config.privoxy.org">web-based user interface</ulink>. The
733 Appendix <quote><link linkend="actionsanat">Troubleshooting: Anatomy of an
734 Action</link></quote> has hints on how to understand and debug actions that
735 <quote>misbehave</quote>.
741 Please see the section <link linkend="contact">Contacting the
742 Developers</link> on how to report bugs, problems with websites or to get
749 Now enjoy surfing with enhanced control, comfort and privacy!
756 <!-- ~~~~~ New section ~~~~~ -->
758 <sect2 id="quickstart-ad-blocking">
759 <title>Quickstart to Ad Blocking</title>
761 NOTE: This section is deliberately redundant for those that don't
762 want to read the whole thing (which is getting lengthy).
765 Ad blocking is but one of <application>Privoxy's</application>
766 array of features. Many of these features are for the technically minded advanced
767 user. But, ad and banner blocking is surely common ground for everybody.
770 This section will provide a quick summary of ad blocking so
771 you can get up to speed quickly without having to read the more extensive
772 information provided below, though this is highly recommended.
775 First a bit of a warning ... blocking ads is much like blocking SPAM: the
776 more aggressive you are about it, the more likely you are to block
777 things that were not intended. And the more likely that some things
778 may not work as intended. So there is a trade off here. If you want
779 extreme ad free browsing, be prepared to deal with more
780 <quote>problem</quote> sites, and to spend more time adjusting the
781 configuration to solve these unintended consequences. In short, there is
782 not an easy way to eliminate <emphasis>all</emphasis> ads. Either take
783 the easy way and settle for <emphasis>most</emphasis> ads blocked with the
784 default configuration, or jump in and tweak it for your personal surfing
785 habits and preferences.
788 Secondly, a brief explanation of <application>Privoxy's </application>
789 <quote>actions</quote>. <quote>Actions</quote> in this context, are
790 the directives we use to tell <application>Privoxy</application> to perform
791 some task relating to HTTP transactions (i.e. web browsing). We tell
792 <application>Privoxy</application> to take some <quote>action</quote>. Each
793 action has a unique name and function. While there are many potential
794 <application>actions</application> in <application>Privoxy's</application>
795 arsenal, only a few are used for ad blocking. <link
796 linkend="actions">Actions</link>, and <link linkend="actions-file">action
797 configuration files</link>, are explained in depth below.
800 Actions are specified in <application>Privoxy's</application> configuration,
801 followed by one or more URLs to which the action should apply. URLs
802 can actually be URL type <link linkend="af-patterns">patterns</link> that use
803 wildcards so they can apply potentially to a range of similar URLs. The
804 actions, together with the URL patterns are called a section.
807 When you connect to a website, the full URL will either match one or more
808 of the sections as defined in <application>Privoxy's</application> configuration,
809 or not. If so, then <application>Privoxy</application> will perform the
810 respective actions. If not, then nothing special happens. Furthermore, web
811 pages may contain embedded, secondary URLs that your web browser will
812 use to load additional components of the page, as it parses the
813 original page's HTML content. An ad image for instance, is just an URL
814 embedded in the page somewhere. The image itself may be on the same server,
815 or a server somewhere else on the Internet. Complex web pages will have many
816 such embedded URLs. &my-app; can deal with each URL individually, so, for
817 instance, the main page text is not touched, but images from such-and-such
822 The most important actions for basic ad blocking are: <literal><link
823 linkend="block">block</link></literal>, <literal><link
824 linkend="handle-as-image">handle-as-image</link></literal>,
826 linkend="handle-as-empty-document">handle-as-empty-document</link></literal>,and
827 <literal><link linkend="set-image-blocker">set-image-blocker</link></literal>:
834 <literal><link linkend="block">block</link></literal> - this is perhaps
835 the single most used action, and is particularly important for ad blocking.
836 This action stops any contact between your browser and any URL patterns
837 that match this action's configuration. It can be used for blocking ads,
838 but also anything that is determined to be unwanted. By itself, it simply
839 stops any communication with the remote server and sends
840 <application>Privoxy</application>'s own built-in BLOCKED page instead to
841 let you now what has happened (with some exceptions, see below).
847 <literal><link linkend="handle-as-image">handle-as-image</link></literal> -
848 tells <application>Privoxy</application> to treat this URL as an image.
849 <application>Privoxy</application>'s default configuration already does this
850 for all common image types (e.g. GIF), but there are many situations where this
851 is not so easy to determine. So we'll force it in these cases. This is particularly
852 important for ad blocking, since only if we know that it's an image of
853 some kind, can we replace it with an image of our choosing, instead of the
854 <application>Privoxy</application> BLOCKED page (which would only result in
855 a <quote>broken image</quote> icon). There are some limitations to this
856 though. For instance, you can't just brute-force an image substitution for
857 an entire HTML page in most situations.
863 <literal><link linkend="handle-as-empty-document">handle-as-empty-document</link></literal> -
864 sends an empty document instead of <application>Privoxy's</application>
865 normal BLOCKED HTML page. This is useful for file types that are neither
866 HTML nor images, such as blocking JavaScript files.
873 linkend="set-image-blocker">set-image-blocker</link></literal> - tells
874 <application>Privoxy</application> what to display in place of an ad image that
875 has hit a block rule. For this to come into play, the URL must match a
876 <literal><link linkend="block">block</link></literal> action somewhere in the
877 configuration, <emphasis>and</emphasis>, it must also match an
878 <literal><link linkend="handle-as-image">handle-as-image</link></literal> action.
881 The configuration options on what to display instead of the ad are:
885 <emphasis>pattern</emphasis> - a checkerboard pattern, so that an ad
886 replacement is obvious. This is the default.
891 <emphasis>blank</emphasis> - A very small empty GIF image is displayed.
892 This is the so-called <quote>invisible</quote> configuration option.
897 <emphasis>http://<URL></emphasis> - A redirect to any image anywhere
898 of the user's choosing (advanced usage).
906 Advanced users will eventually want to explore &my-app;
907 <literal><link linkend="filter">filters</link></literal> as well. Filters
908 are very different from <literal><link
909 linkend="block">blocks</link></literal>.
910 A <quote>block</quote> blocks a site, page, or unwanted contented. Filters
911 are a way of filtering or modifying what is actually on the page. An example
912 filter usage: a text replacement of <quote>no-no</quote> for
913 <quote>nasty-word</quote>. That is a very simple example. This process can be
914 used for ad blocking, but it is more in the realm of advanced usage and has
915 some pitfalls to be wary off.
919 The quickest way to adjust any of these settings is with your browser through
920 the special <application>Privoxy</application> editor at <ulink
921 url="http://config.privoxy.org/show-status">http://config.privoxy.org/show-status</ulink>
922 (shortcut: <ulink url="http://p.p/">http://p.p/show-status</ulink>). This
923 is an internal page, and does not require Internet access.
927 Note that as of <application>Privoxy</application> 3.0.7 beta the
928 action editor is disabled by default. Check the
929 <ulink url="config.html#ENABLE-EDIT-ACTIONS">enable-edit-actions
930 section in the configuration file</ulink> to learn why and in which
931 cases it's safe to enable again.
935 If you decided to enable the action editor, select the appropriate
936 <quote>actions</quote> file, and click
937 <quote><guibutton>Edit</guibutton></quote>. It is best to put personal or
938 local preferences in <filename>user.action</filename> since this is not
939 meant to be overwritten during upgrades, and will over-ride the settings in
940 other files. Here you can insert new <quote>actions</quote>, and URLs for ad
941 blocking or other purposes, and make other adjustments to the configuration.
942 <application>Privoxy</application> will detect these changes automatically.
946 A quick and simple step by step example:
953 Right click on the ad image to be blocked, then select
954 <quote><guimenuitem>Copy Link Location</guimenuitem></quote> from the
962 url="http://config.privoxy.org/show-status">http://config.privoxy.org/show-status</ulink>
967 Find <filename>user.action</filename> in the top section, and click
968 on <quote><guibutton>Edit</guibutton></quote>:
971 <!-- image of editor and actions files selections -->
972 <figure pgwide="0" float="0"><title>Actions Files in Use</title>
975 <imagedata fileref="files-in-use.jpg" format="jpg">
978 <phrase>[ Screenshot of Actions Files in Use ]</phrase>
986 You should have a section with only
987 <literal><link linkend="block">block</link></literal> listed under
988 <quote>Actions:</quote>.
989 If not, click a <quote><guibutton>Insert new section below</guibutton></quote>
990 button, and in the new section that just appeared, click the
991 <guibutton>Edit</guibutton> button right under the word <quote>Actions:</quote>.
992 This will bring up a list of all actions. Find
993 <literal><link linkend="block">block</link></literal> near the top, and click
994 in the <quote>Enabled</quote> column, then <quote><guibutton>Submit</guibutton></quote>
1000 Now, in the <literal><link linkend="block">block</link></literal> actions section,
1001 click the <quote><guibutton>Add</guibutton></quote> button, and paste the URL the
1002 browser got from <quote><guimenuitem>Copy Link Location</guimenuitem></quote>.
1003 Remove the <literal>http://</literal> at the beginning of the URL. Then, click
1004 <quote><guibutton>Submit</guibutton></quote> (or
1005 <quote><guibutton>OK</guibutton></quote> if in a pop-up window).
1010 Now go back to the original page, and press <keycap>SHIFT-Reload</keycap>
1011 (or flush all browser caches). The image should be gone now.
1018 This is a very crude and simple example. There might be good reasons to use a
1019 wildcard pattern match to include potentially similar images from the same
1020 site. For a more extensive explanation of <quote>patterns</quote>, and
1021 the entire actions concept, see <link linkend="actions-file">the Actions
1026 For advanced users who want to hand edit their config files, you might want
1027 to now go to the <link linkend="act-examples">Actions Files Tutorial</link>.
1028 The ideas explained therein also apply to the web-based editor.
1031 There are also various
1032 <link linkend="filter">filters</link> that can be used for ad blocking
1033 (filters are a special subset of actions). These
1034 fall into the <quote>advanced</quote> usage category, and are explained in
1035 depth in later sections.
1042 <!-- ~ End section ~ -->
1045 <!-- ~~~~~ New section ~~~~~ -->
1046 <sect1 id="startup">
1047 <title>Starting Privoxy</title>
1049 Before launching <application>Privoxy</application> for the first time, you
1050 will want to configure your browser(s) to use
1051 <application>Privoxy</application> as a HTTP and HTTPS (SSL)
1052 <ulink url="http://en.wikipedia.org/wiki/Proxy_server">proxy</ulink>. The default is
1053 127.0.0.1 (or localhost) for the proxy address, and port 8118 (earlier versions
1054 used port 8000). This is the one configuration step <emphasis>that must be done
1058 Please note that <application>Privoxy</application> can only proxy HTTP and
1059 HTTPS traffic. It will not work with FTP or other protocols.
1062 <!-- image of Mozilla Proxy configuration -->
1063 <figure pgwide="0" float="0"><title>Proxy Configuration Showing
1064 Mozilla/Netscape HTTP and HTTPS (SSL) Settings</title>
1067 <imagedata fileref="proxy_setup.jpg" format="jpg">
1070 <phrase>[ Screenshot of Mozilla Proxy Configuration ]</phrase>
1077 With <application>Firefox</application>, this is typically set under:
1081 <guibutton>Tools</guibutton> -> <guibutton>Options</guibutton> -> <guibutton>Advanced</guibutton> -> <guibutton>Network</guibutton> -><guibutton>Connection</guibutton> -> <guibutton>Settings</guibutton>
1085 Or optionally on some platforms:
1089 <guibutton>Edit</guibutton> -> <guibutton>Preferences</guibutton> -> <guibutton>General</guibutton> -> <guibutton>Connection Settings</guibutton> -> <guibutton>Manual Proxy Configuration</guibutton>
1094 With <application>Netscape</application> (and
1095 <application>Mozilla</application>), this can be set under:
1100 <!-- Mix ascii and gui art, something for everybody -->
1101 <!-- spacing on this is tricky -->
1102 <guibutton>Edit</guibutton> -> <guibutton>Preferences</guibutton> -> <guibutton>Advanced</guibutton> -> <guibutton>Proxies</guibutton> -> <guibutton>HTTP Proxy</guibutton>
1106 For <application>Internet Explorer v.5-7</application>:
1110 <guibutton>Tools</guibutton> -> <guibutton>Internet Options</guibutton> -> <guibutton>Connections</guibutton> -> <guibutton>LAN Settings</guibutton>
1114 Then, check <quote>Use Proxy</quote> and fill in the appropriate info
1115 (Address: 127.0.0.1, Port: 8118). Include HTTPS (SSL), if you want HTTPS
1116 proxy support too (sometimes labeled <quote>Secure</quote>). Make sure any
1117 checkboxes like <quote>Use the same proxy server for all protocols</quote> is
1118 <emphasis>UNCHECKED</emphasis>. You want only HTTP and HTTPS (SSL)!
1121 <!-- image of IE Proxy configuration -->
1122 <figure pgwide="0" float="0"><title>Proxy Configuration Showing
1123 Internet Explorer HTTP and HTTPS (Secure) Settings</title>
1126 <imagedata fileref="proxy2.jpg" format="jpg">
1129 <phrase>[ Screenshot of IE Proxy Configuration ]</phrase>
1136 After doing this, flush your browser's disk and memory caches to force a
1137 re-reading of all pages and to get rid of any ads that may be cached. Remove
1138 any <ulink url="http://en.wikipedia.org/wiki/Browser_cookie">cookies</ulink>,
1139 if you want <application>Privoxy</application> to manage that. You are now
1140 ready to start enjoying the benefits of using
1141 <application>Privoxy</application>!
1145 <application>Privoxy</application> itself is typically started by specifying the
1146 main configuration file to be used on the command line. If no configuration
1147 file is specified on the command line, <application>Privoxy</application>
1148 will look for a file named <filename>config</filename> in the current
1149 directory. Except on Win32 where it will try <filename>config.txt</filename>.
1152 <sect2 id="start-debian">
1153 <title>Debian</title>
1155 We use a script. Note that Debian typically starts &my-app; upon booting per
1156 default. It will use the file
1157 <filename>/etc/privoxy/config</filename> as its main configuration
1161 # /etc/init.d/privoxy start
1165 <sect2 id="start-freebsd">
1166 <title>FreeBSD and ElectroBSD</title>
1168 To start <application>Privoxy</application> upon booting, add
1169 "privoxy_enable='YES'" to <filename>/etc/rc.conf</filename>.
1170 <application>Privoxy</application> will use
1171 <filename>/usr/local/etc/privoxy/config</filename> as its main
1175 If you installed <application>Privoxy</application> into a jail, the
1176 paths above are relative to the jail root.
1179 To start <application>Privoxy</application> manually, run:
1182 # service privoxy onestart
1186 <sect2 id="start-windows">
1187 <title>Windows</title>
1189 Click on the &my-app; Icon to start <application>Privoxy</application>. If no configuration file is
1190 specified on the command line, <application>Privoxy</application> will look
1191 for a file named <filename>config.txt</filename>. Note that Windows will
1192 automatically start &my-app; when the system starts if you chose that option
1196 <application>Privoxy</application> can run with full Windows service functionality.
1197 On Windows only, the &my-app; program has two new command line arguments
1198 to install and uninstall &my-app; as a service. See the
1199 <link linkend="installation-pack-win">Windows Installation
1200 instructions</link> for details.
1204 <sect2 id="start-unices">
1205 <title>Generic instructions for Unix derivates (Solaris, NetBSD, HP-UX etc.)</title>
1207 Example Unix startup command:
1210 # /usr/sbin/privoxy --user privoxy /etc/privoxy/config
1213 Note that if you installed <application>Privoxy</application> through
1214 a package manager, the package will probably contain a platform-specific
1215 script or configuration file to start <application>Privoxy</application>
1220 <sect2 id="start-os2">
1223 During installation, <application>Privoxy</application> is configured to
1224 start automatically when the system restarts. You can start it manually by
1225 double-clicking on the <application>Privoxy</application> icon in the
1226 <application>Privoxy</application> folder.
1230 <sect2 id="start-macosx">
1231 <title>Mac OS X</title>
1233 The privoxy service will automatically start after a successful installation
1234 (and thereafter every time your computer starts up) however you will need to
1235 configure your web browser(s) to use it. To do so, configure them to use a
1236 proxy for HTTP and HTTPS at the address 127.0.0.1:8118.
1239 To prevent the privoxy service from automatically starting when your computer
1240 starts up, remove or rename the file <literal>/Library/LaunchDaemons/org.ijbswa.privoxy.plist</literal>
1241 (on OS X 10.5 and higher) or the folder named
1242 <literal>/Library/StartupItems/Privoxy</literal> (on OS X 10.4 'Tiger').
1245 To manually start or stop the privoxy service, use the scripts startPrivoxy.sh
1246 and stopPrivoxy.sh supplied in /Applications/Privoxy. They must be run from an
1247 administrator account, using sudo.
1255 See the section <link linkend="cmdoptions">Command line options</link> for
1259 must find a better place for this paragraph
1262 The included default configuration files should give a reasonable starting
1263 point. Most of the per site configuration is done in the
1264 <ulink url="actions-file.html"><quote>actions</quote></ulink> files. These are
1265 where various cookie actions are defined, ad and banner blocking, and other
1266 aspects of <application>Privoxy</application> configuration. There are several
1267 such files included, with varying levels of aggressiveness.
1271 You will probably want to keep an eye out for sites for which you may prefer
1272 persistent cookies, and add these to your actions configuration as needed. By
1273 default, most of these will be accepted only during the current browser
1274 session (aka <quote>session cookies</quote>), unless you add them to the
1275 configuration. If you want the browser to handle this instead, you will need
1276 to edit <filename>user.action</filename> (or through the web based interface)
1277 and disable this feature. If you use more than one browser, it would make
1278 more sense to let <application>Privoxy</application> handle this. In which
1279 case, the browser(s) should be set to accept all cookies.
1283 Another feature where you will probably want to define exceptions for trusted
1284 sites is the popup-killing (through <ulink
1285 url="actions-file.html#FILTER-POPUPS"><quote>+filter{popups}</quote></ulink>),
1286 because your favorite shopping, banking, or leisure site may need
1287 popups (explained below).
1291 <application>Privoxy</application> does not support all of the optional HTTP/1.1
1292 features yet. In the unlikely event that you experience inexplicable problems
1293 with browsers that use HTTP/1.1 per default
1294 (like <application>Mozilla</application> or recent versions of I.E.), you might
1295 try to force HTTP/1.0 compatibility. For Mozilla, look under <literal>Edit ->
1296 Preferences -> Debug -> Networking</literal>.
1297 Alternatively, set the <quote>+downgrade-http-version</quote> config option in
1298 <filename>default.action</filename> which will downgrade your browser's HTTP
1299 requests from HTTP/1.1 to HTTP/1.0 before processing them.
1303 After running <application>Privoxy</application> for a while, you can
1304 start to fine tune the configuration to suit your personal, or site,
1305 preferences and requirements. There are many, many aspects that can
1306 be customized. <quote>Actions</quote>
1307 can be adjusted by pointing your browser to
1308 <ulink url="http://config.privoxy.org/">http://config.privoxy.org/</ulink>
1309 (shortcut: <ulink url="http://p.p/">http://p.p/</ulink>),
1310 and then follow the link to <quote>View & Change the Current Configuration</quote>.
1311 (This is an internal page and does not require Internet access.)
1315 In fact, various aspects of <application>Privoxy</application>
1316 configuration can be viewed from this page, including
1317 current configuration parameters, source code version numbers,
1318 the browser's request headers, and <quote>actions</quote> that apply
1319 to a given URL. In addition to the actions file
1320 editor mentioned above, <application>Privoxy</application> can also
1321 be turned <quote>on</quote> and <quote>off</quote> (toggled) from this page.
1325 If you encounter problems, try loading the page without
1326 <application>Privoxy</application>. If that helps, enter the URL where
1327 you have the problems into <ulink url="http://p.p/show-url-info">the browser
1328 based rule tracing utility</ulink>. See which rules apply and why, and
1329 then try turning them off for that site one after the other, until the problem
1330 is gone. When you have found the culprit, you might want to turn the rest on
1335 If the above paragraph sounds gibberish to you, you might want to <link
1336 linkend="actions-file">read more about the actions concept</link>
1337 or even dive deep into the <link linkend="actionsanat">Appendix
1342 If you can't get rid of the problem at all, think you've found a bug in
1343 Privoxy, want to propose a new feature or smarter rules, please see the
1344 section <link linkend="contact"><quote>Contacting the
1345 Developers</quote></link> below.
1350 <!-- ~~~~~ New section ~~~~~ -->
1351 <sect2 id="cmdoptions">
1352 <title>Command Line Options</title>
1354 <application>Privoxy</application> may be invoked with the following
1355 command-line options:
1362 <emphasis>--config-test</emphasis>
1365 Exit after loading the configuration files before binding to
1366 the listen address. The exit code signals whether or not the
1367 configuration files have been successfully loaded.
1370 If the exit code is 1, at least one of the configuration files
1371 is invalid, if it is 0, all the configuration files have been
1372 successfully loaded (but may still contain errors that can
1373 currently only be detected at run time).
1376 This option doesn't affect the log setting, combination with
1377 <emphasis>--no-daemon</emphasis> is recommended if a configured
1378 log file shouldn't be used.
1383 <emphasis>--version</emphasis>
1386 Print version info and exit. Unix only.
1391 <emphasis>--help</emphasis>
1394 Print short usage info and exit. Unix only.
1399 <emphasis>--no-daemon</emphasis>
1402 Don't become a daemon, i.e. don't fork and become process group
1403 leader, and don't detach from controlling tty. Unix only.
1408 <emphasis>--pidfile FILE</emphasis>
1411 On startup, write the process ID to <emphasis>FILE</emphasis>. Delete the
1412 <emphasis>FILE</emphasis> on exit. Failure to create or delete the
1413 <emphasis>FILE</emphasis> is non-fatal. If no <emphasis>FILE</emphasis>
1414 option is given, no PID file will be used. Unix only.
1419 <emphasis>--user USER[.GROUP]</emphasis>
1422 After (optionally) writing the PID file, assume the user ID of
1423 <emphasis>USER</emphasis>, and if included the GID of GROUP. Exit if the
1424 privileges are not sufficient to do so. Unix only.
1429 <emphasis>--chroot</emphasis>
1432 Before changing to the user ID given in the <emphasis>--user</emphasis> option,
1433 chroot to that user's home directory, i.e. make the kernel pretend to the &my-app;
1434 process that the directory tree starts there. If set up carefully, this can limit
1435 the impact of possible vulnerabilities in &my-app; to the files contained in that hierarchy.
1441 <emphasis>--pre-chroot-nslookup hostname</emphasis>
1444 Specifies a hostname (for example www.privoxy.org) to look up before doing a chroot.
1445 On some systems, initializing the resolver library involves reading config files from
1446 /etc and/or loading additional shared libraries from /lib.
1447 On these systems, doing a hostname lookup before the chroot reduces
1448 the number of files that must be copied into the chroot tree.
1451 For fastest startup speed, a good value is a hostname that is not in /etc/hosts but that
1452 your local name server (listed in /etc/resolv.conf) can resolve without recursion
1453 (that is, without having to ask any other name servers). The hostname need not exist,
1454 but if it doesn't, an error message (which can be ignored) will be output.
1460 <emphasis>configfile</emphasis>
1463 If no <emphasis>configfile</emphasis> is included on the command line,
1464 <application>Privoxy</application> will look for a file named
1465 <quote>config</quote> in the current directory (except on Win32
1466 where it will look for <quote>config.txt</quote> instead). Specify
1467 full path to avoid confusion. If no config file is found,
1468 <application>Privoxy</application> will fail to start.
1475 On <application>MS Windows</application> only there are two additional
1476 command-line options to allow <application>Privoxy</application> to install and
1477 run as a <emphasis>service</emphasis>. See the
1478 <link linkend="installation-pack-win">Window Installation section</link>
1486 <!-- ~ End section ~ -->
1489 <!-- ~~~~~ New section ~~~~~ -->
1490 <sect1 id="configuration"><title>Privoxy Configuration</title>
1492 All <application>Privoxy</application> configuration is stored
1493 in text files. These files can be edited with a text editor.
1494 Many important aspects of <application>Privoxy</application> can
1495 also be controlled easily with a web browser.
1499 <!-- ~~~~~ New section ~~~~~ -->
1501 <sect2 id="control-with-webbrowser">
1502 <title>Controlling Privoxy with Your Web Browser</title>
1504 <application>Privoxy</application>'s user interface can be reached through the special
1505 URL <ulink url="http://config.privoxy.org/">http://config.privoxy.org/</ulink>
1506 (shortcut: <ulink url="http://p.p/">http://p.p/</ulink>),
1507 which is a built-in page and works without Internet access.
1508 You will see the following section:
1511 <!-- Needs to be put in a table and colorized -->
1512 <screen><!-- want the background color that goes with screen -->
1514 <bridgehead renderas="sect2"> Privoxy Menu</bridgehead>
1517 ▪ <ulink url="http://config.privoxy.org/show-status">View & change the current configuration</ulink>
1520 ▪ <ulink url="http://config.privoxy.org/show-request">View the request headers.</ulink>
1523 ▪ <ulink url="http://config.privoxy.org/show-url-info">Look up which actions apply to a URL and why</ulink>
1526 ▪ <ulink url="http://config.privoxy.org/toggle">Toggle Privoxy on or off</ulink>
1529 ▪ <ulink
1530 url="https://www.privoxy.org/&p-version;/user-manual/">Documentation</ulink>
1538 This should be self-explanatory. Note the first item leads to an editor for the
1539 <link linkend="actions-file">actions files</link>, which is where the ad, banner,
1540 cookie, and URL blocking magic is configured as well as other advanced features of
1541 <application>Privoxy</application>. This is an easy way to adjust various
1542 aspects of <application>Privoxy</application> configuration. The actions
1543 file, and other configuration files, are explained in detail below.
1547 <quote>Toggle Privoxy On or Off</quote> is handy for sites that might
1548 have problems with your current actions and filters. You can in fact use
1549 it as a test to see whether it is <application>Privoxy</application>
1550 causing the problem or not. <application>Privoxy</application> continues
1551 to run as a proxy in this case, but all manipulation is disabled, i.e.
1552 <application>Privoxy</application> acts like a normal forwarding proxy.
1556 Note that several of the features described above are disabled by default
1557 in <application>Privoxy</application> 3.0.7 beta and later.
1559 <ulink url="config.html">configuration file</ulink> to learn why
1560 and in which cases it's safe to enable them again.
1565 <!-- ~ End section ~ -->
1570 <!-- ~~~~~ New section ~~~~~ -->
1572 <sect2 id="confoverview">
1573 <title>Configuration Files Overview</title>
1575 For Unix, *BSD and GNU/Linux, all configuration files are located in
1576 <filename>/etc/privoxy/</filename> by default. For MS Windows and OS/2
1577 these are all in the same directory as the
1578 <application>Privoxy</application> executable. <![%p-not-stable;[ The name
1579 and number of configuration files has changed from previous versions, and is
1580 subject to change as development progresses.]]>
1584 The installed defaults provide a reasonable starting point, though
1585 some settings may be aggressive by some standards. For the time being, the
1586 principle configuration files are:
1593 The <link linkend="config">main configuration file</link> is named <filename>config</filename>
1594 on GNU/Linux, Unix, BSD, and OS/2, and <filename>config.txt</filename>
1595 on Windows. This is a required file.
1601 <filename>match-all.action</filename> is used to define which <quote>actions</quote>
1602 relating to banner-blocking, images, pop-ups, content modification, cookie handling
1603 etc should be applied by default. It should be the first actions file loaded.
1606 <filename>default.action</filename> defines many exceptions (both positive and negative)
1607 from the default set of actions that's configured in <filename>match-all.action</filename>.
1608 It should be the second actions file loaded and shouldn't be edited by the user.
1611 Multiple actions files may be defined in <filename>config</filename>. These
1612 are processed in the order they are defined. Local customizations and locally
1613 preferred exceptions to the default policies as defined in
1614 <filename>match-all.action</filename> (which you will most probably want
1615 to define sooner or later) are best applied in <filename>user.action</filename>,
1616 where you can preserve them across upgrades. The file isn't installed by all
1617 installers, but you can easily create it yourself with a text editor.
1620 There is also a web based editor that can be accessed from
1622 url="http://config.privoxy.org/show-status">http://config.privoxy.org/show-status</ulink>
1624 url="http://p.p/show-status">http://p.p/show-status</ulink>) for the
1625 various actions files.
1631 <quote>Filter files</quote> (the <link linkend="filter-file">filter
1632 file</link>) can be used to re-write the raw page content, including
1633 viewable text as well as embedded HTML and JavaScript, and whatever else
1634 lurks on any given web page. The filtering jobs are only pre-defined here;
1635 whether to apply them or not is up to the actions files.
1636 <filename>default.filter</filename> includes various filters made
1637 available for use by the developers. Some are much more intrusive than
1638 others, and all should be used with caution. You may define additional
1639 filter files in <filename>config</filename> as you can with
1640 actions files. We suggest <filename>user.filter</filename> for any
1641 locally defined filters or customizations.
1648 The syntax of the configuration and filter files may change between different
1649 Privoxy versions, unfortunately some enhancements cost backwards compatibility.
1650 <!-- Add link to documentation-->
1654 All files use the <quote><literal>#</literal></quote> character to denote a
1655 comment (the rest of the line will be ignored) and understand line continuation
1656 through placing a backslash ("<literal>\</literal>") as the very last character
1657 in a line. If the <literal>#</literal> is preceded by a backslash, it looses
1658 its special function. Placing a <literal>#</literal> in front of an otherwise
1659 valid configuration line to prevent it from being interpreted is called "commenting
1660 out" that line. Blank lines are ignored.
1664 The actions files and filter files
1665 can use Perl style <link linkend="regex">regular expressions</link> for
1666 maximum flexibility.
1670 After making any changes, there is no need to restart
1671 <application>Privoxy</application> in order for the changes to take
1672 effect. <application>Privoxy</application> detects such changes
1673 automatically. Note, however, that it may take one or two additional
1674 requests for the change to take effect. When changing the listening address
1675 of <application>Privoxy</application>, these <quote>wake up</quote> requests
1676 must obviously be sent to the <emphasis>old</emphasis> listening address.
1681 While under development, the configuration content is subject to change.
1682 The below documentation may not be accurate by the time you read this.
1683 Also, what constitutes a <quote>default</quote> setting, may change, so
1684 please check all your configuration files on important issues.
1690 <!-- ~ End section ~ -->
1693 <!-- ~~~~~~~~ New section Header ~~~~~~~~~ -->
1695 <!-- **************************************************** -->
1696 <!-- Include config.sgml here -->
1697 <!-- This is where the entire config file is detailed. -->
1699 <!-- end include -->
1702 <!-- ~ End section ~ -->
1706 <!-- ~~~~~~~~ New section Header ~~~~~~~~~ -->
1708 <sect1 id="actions-file"><title>Actions Files</title>
1712 XXX: similar descriptions are in the Configuration Files sections.
1713 We should only describe them at one place.
1716 The actions files are used to define what <emphasis>actions</emphasis>
1717 <application>Privoxy</application> takes for which URLs, and thus determines
1718 how ad images, cookies and various other aspects of HTTP content and
1719 transactions are handled, and on which sites (or even parts thereof).
1720 There are a number of such actions, with a wide range of functionality.
1721 Each action does something a little different.
1722 These actions give us a veritable arsenal of tools with which to exert
1723 our control, preferences and independence. Actions can be combined so that
1724 their effects are aggregated when applied against a given set of URLs.
1728 are three action files included with <application>Privoxy</application> with
1734 <filename>match-all.action</filename> - is used to define which
1735 <quote>actions</quote> relating to banner-blocking, images, pop-ups,
1736 content modification, cookie handling etc should be applied by default.
1737 It should be the first actions file loaded
1742 <filename>default.action</filename> - defines many exceptions (both
1743 positive and negative) from the default set of actions that's configured
1744 in <filename>match-all.action</filename>. It is a set of rules that should
1745 work reasonably well as-is for most users. This file is only supposed to
1746 be edited by the developers. It should be the second actions file loaded.
1751 <filename>user.action</filename> - is intended to be for local site
1752 preferences and exceptions. As an example, if your ISP or your bank
1753 has specific requirements, and need special handling, this kind of
1754 thing should go here. This file will not be upgraded.
1759 <guibutton>Edit</guibutton> <guibutton>Set to Cautious</guibutton> <guibutton>Set to Medium</guibutton> <guibutton>Set to Advanced</guibutton>
1762 These have increasing levels of aggressiveness <emphasis>and have no
1763 influence on your browsing unless you select them explicitly in the
1764 editor</emphasis>. A default installation should be pre-set to
1765 <literal>Cautious</literal>. New users should try this for a while before
1766 adjusting the settings to more aggressive levels. The more aggressive
1767 the settings, then the more likelihood there is of problems such as sites
1768 not working as they should.
1771 The <guibutton>Edit</guibutton> button allows you to turn each
1772 action on/off individually for fine-tuning. The <guibutton>Cautious</guibutton>
1773 button changes the actions list to low/safe settings which will activate
1774 ad blocking and a minimal set of &my-app;'s features, and subsequently
1775 there will be less of a chance for accidental problems. The
1776 <guibutton>Medium</guibutton> button sets the list to a medium level of
1777 other features and a low level set of privacy features. The
1778 <guibutton>Advanced</guibutton> button sets the list to a high level of
1779 ad blocking and medium level of privacy. See the chart below. The latter
1780 three buttons over-ride any changes via with the
1781 <guibutton>Edit</guibutton> button. More fine-tuning can be done in the
1782 lower sections of this internal page.
1785 While the actions file editor allows to enable these settings in all
1786 actions files, they are only supposed to be enabled in the first one
1787 to make sure you don't unintentionally overrule earlier rules.
1790 The default profiles, and their associated actions, as pre-defined in
1791 <filename>default.action</filename> are:
1793 <table frame=all><title>Default Configurations</title>
1794 <tgroup cols=4 align=left colsep=1 rowsep=1>
1795 <colspec colname=c1>
1796 <colspec colname=c2>
1797 <colspec colname=c3>
1798 <colspec colname=c4>
1801 <entry>Feature</entry>
1802 <entry>Cautious</entry>
1803 <entry>Medium</entry>
1804 <entry>Advanced</entry>
1809 <!-- <entry>f1</entry> -->
1810 <!-- <entry>f2</entry> -->
1811 <!-- <entry>f3</entry> -->
1812 <!-- <entry>f4</entry> -->
1818 <entry>Ad-blocking Aggressiveness</entry>
1819 <entry>medium</entry>
1825 <entry>Ad-filtering by size</entry>
1832 <entry>Ad-filtering by link</entry>
1838 <entry>Pop-up killing</entry>
1839 <entry>blocks only</entry>
1840 <entry>blocks only</entry>
1841 <entry>blocks only</entry>
1845 <entry>Privacy Features</entry>
1847 <entry>medium</entry>
1848 <entry>medium/high</entry>
1852 <entry>Cookie handling</entry>
1854 <entry>session-only</entry>
1859 <entry>Referer forging</entry>
1866 <entry>GIF de-animation</entry>
1873 <entry>Fast redirects</entry>
1880 <entry>HTML taming</entry>
1887 <entry>JavaScript taming</entry>
1894 <entry>Web-bug killing</entry>
1901 <entry>Image tag reordering</entry>
1915 The list of actions files to be used are defined in the main configuration
1916 file, and are processed in the order they are defined (e.g.
1917 <filename>default.action</filename> is typically processed before
1918 <filename>user.action</filename>). The content of these can all be viewed and
1920 url="http://config.privoxy.org/show-status">http://config.privoxy.org/show-status</ulink>.
1921 The over-riding principle when applying actions, is that the last action that
1922 matches a given URL wins. The broadest, most general rules go first
1923 (defined in <filename>default.action</filename>),
1924 followed by any exceptions (typically also in
1925 <filename>default.action</filename>), which are then followed lastly by any
1926 local preferences (typically in <emphasis>user</emphasis><filename>.action</filename>).
1927 Generally, <filename>user.action</filename> has the last word.
1931 An actions file typically has multiple sections. If you want to use
1932 <quote>aliases</quote> in an actions file, you have to place the (optional)
1933 <link linkend="aliases">alias section</link> at the top of that file.
1934 Then comes the default set of rules which will apply universally to all
1935 sites and pages (be <emphasis>very careful</emphasis> with using such a
1936 universal set in <filename>user.action</filename> or any other actions file after
1937 <filename>default.action</filename>, because it will override the result
1938 from consulting any previous file). And then below that,
1939 exceptions to the defined universal policies. You can regard
1940 <filename>user.action</filename> as an appendix to <filename>default.action</filename>,
1941 with the advantage that it is a separate file, which makes preserving your
1942 personal settings across <application>Privoxy</application> upgrades easier.
1946 Actions can be used to block anything you want, including ads, banners, or
1947 just some obnoxious URL whose content you would rather not see. Cookies can be accepted
1948 or rejected, or accepted only during the current browser session (i.e. not
1949 written to disk), content can be modified, some JavaScripts tamed, user-tracking
1950 fooled, and much more. See below for a <link linkend="actions">complete list
1954 <!-- ~~~~~ New section ~~~~~ -->
1955 <sect2 id="right-mix">
1956 <title>Finding the Right Mix</title>
1958 Note that some <link linkend="actions">actions</link>, like cookie suppression
1959 or script disabling, may render some sites unusable that rely on these
1960 techniques to work properly. Finding the right mix of actions is not always easy and
1961 certainly a matter of personal taste. And, things can always change, requiring
1962 refinements in the configuration. In general, it can be said that the more
1963 <quote>aggressive</quote> your default settings (in the top section of the
1964 actions file) are, the more exceptions for <quote>trusted</quote> sites you
1965 will have to make later. If, for example, you want to crunch all cookies per
1966 default, you'll have to make exceptions from that rule for sites that you
1967 regularly use and that require cookies for actually useful purposes, like maybe
1968 your bank, favorite shop, or newspaper.
1972 We have tried to provide you with reasonable rules to start from in the
1973 distribution actions files. But there is no general rule of thumb on these
1974 things. There just are too many variables, and sites are constantly changing.
1975 Sooner or later you will want to change the rules (and read this chapter again :).
1979 <!-- ~~~~~ New section ~~~~~ -->
1980 <sect2 id="how-to-edit">
1981 <title>How to Edit</title>
1983 The easiest way to edit the actions files is with a browser by
1984 using our browser-based editor, which can be reached from <ulink
1985 url="http://config.privoxy.org/show-status">http://config.privoxy.org/show-status</ulink>.
1986 Note: the config file option <link
1987 linkend="enable-edit-actions">enable-edit-actions</link> must be enabled for
1988 this to work. The editor allows both fine-grained control over every single
1989 feature on a per-URL basis, and easy choosing from wholesale sets of defaults
1990 like <quote>Cautious</quote>, <quote>Medium</quote> or
1991 <quote>Advanced</quote>. Warning: the <quote>Advanced</quote> setting is more
1992 aggressive, and will be more likely to cause problems for some sites.
1993 Experienced users only!
1997 If you prefer plain text editing to GUIs, you can of course also directly edit the
1998 the actions files with your favorite text editor. Look at
1999 <filename>default.action</filename> which is richly commented with many
2005 <sect2 id="actions-apply">
2006 <title>How Actions are Applied to Requests</title>
2008 Actions files are divided into sections. There are special sections,
2009 like the <quote><link linkend="aliases">alias</link></quote> sections which will
2010 be discussed later. For now let's concentrate on regular sections: They have a
2011 heading line (often split up to multiple lines for readability) which consist
2012 of a list of actions, separated by whitespace and enclosed in curly braces.
2013 Below that, there is a list of URL and tag patterns, each on a separate line.
2017 To determine which actions apply to a request, the URL of the request is
2018 compared to all URL patterns in each <quote>action file</quote>.
2019 Every time it matches, the list of applicable actions for the request is
2020 incrementally updated, using the heading of the section in which the
2021 pattern is located. The same is done again for tags and tag patterns later on.
2025 If multiple applying sections set the same action differently,
2026 the last match wins. If not, the effects are aggregated.
2027 E.g. a URL might match a regular section with a heading line of <literal>{
2028 +<link linkend="handle-as-image">handle-as-image</link> }</literal>,
2029 then later another one with just <literal>{
2030 +<link linkend="block">block</link> }</literal>, resulting
2031 in <emphasis>both</emphasis> actions to apply. And there may well be
2032 cases where you will want to combine actions together. Such a section then
2037 { +<literal>handle-as-image</literal> +<literal>block{Banner ads.}</literal> }
2038 # Block these as if they were images. Send no block page.
2040 media.example.com/.*banners
2041 .example.com/images/ads/</screen>
2044 You can trace this process for URL patterns and any given URL by visiting <ulink
2045 url="http://config.privoxy.org/show-url-info">http://config.privoxy.org/show-url-info</ulink>.
2049 Examples and more detail on this is provided in the Appendix, <link linkend="ACTIONSANAT">
2050 Troubleshooting: Anatomy of an Action</link> section.
2054 <!-- ~~~~~ New section ~~~~~ -->
2055 <sect2 id="af-patterns">
2056 <title>Patterns</title>
2058 As mentioned, <application>Privoxy</application> uses <quote>patterns</quote>
2059 to determine what <emphasis>actions</emphasis> might apply to which sites and
2060 pages your browser attempts to access. These <quote>patterns</quote> use wild
2061 card type <emphasis>pattern</emphasis> matching to achieve a high degree of
2062 flexibility. This allows one expression to be expanded and potentially match
2063 against many similar patterns.
2067 Generally, an URL pattern has the form
2068 <literal><host><port>/<path></literal>, where the
2069 <literal><host></literal>, the <literal><port></literal>
2070 and the <literal><path></literal> are optional. (This is why the special
2071 <literal>/</literal> pattern matches all URLs). Note that the protocol
2072 portion of the URL pattern (e.g. <literal>http://</literal>) should
2073 <emphasis>not</emphasis> be included in the pattern. This is assumed already!
2076 The pattern matching syntax is different for the host and path parts of
2077 the URL. The host part uses a simple globbing type matching technique,
2078 while the path part uses more flexible
2079 <ulink url="http://en.wikipedia.org/wiki/Regular_expressions"><quote>Regular
2080 Expressions</quote></ulink> (POSIX 1003.2).
2083 The port part of a pattern is a decimal port number preceded by a colon
2084 (<literal>:</literal>). If the host part contains a numerical IPv6 address,
2085 it has to be put into angle brackets
2086 (<literal><</literal>, <literal>></literal>).
2091 <term><literal>www.example.com/</literal></term>
2094 is a host-only pattern and will match any request to <literal>www.example.com</literal>,
2095 regardless of which document on that server is requested. So ALL pages in
2096 this domain would be covered by the scope of this action. Note that a
2097 simple <literal>example.com</literal> is different and would NOT match.
2102 <term><literal>www.example.com</literal></term>
2105 means exactly the same. For host-only patterns, the trailing <literal>/</literal> may
2111 <term><literal>www.example.com/index.html</literal></term>
2114 matches all the documents on <literal>www.example.com</literal>
2115 whose name starts with <literal>/index.html</literal>.
2120 <term><literal>www.example.com/index.html$</literal></term>
2123 matches only the single document <literal>/index.html</literal>
2124 on <literal>www.example.com</literal>.
2129 <term><literal>/index.html$</literal></term>
2132 matches the document <literal>/index.html</literal>, regardless of the domain,
2133 i.e. on <emphasis>any</emphasis> web server anywhere.
2138 <term><literal>/</literal></term>
2141 Matches any URL because there's no requirement for either the
2142 domain or the path to match anything.
2147 <term><literal>:8000/</literal></term>
2150 Matches any URL pointing to TCP port 8000.
2155 <term><literal>10.0.0.1/</literal></term>
2158 Matches any URL with the host address <literal>10.0.0.1</literal>.
2159 (Note that the real URL uses plain brackets, not angle brackets.)
2164 <term><literal><2001:db8::1>/</literal></term>
2167 Matches any URL with the host address <literal>2001:db8::1</literal>.
2168 (Note that the real URL uses plain brackets, not angle brackets.)
2173 <term><literal>index.html</literal></term>
2176 matches nothing, since it would be interpreted as a domain name and
2177 there is no top-level domain called <literal>.html</literal>. So its
2185 <!-- ~~~~~ New section ~~~~~ -->
2186 <sect3 id="host-pattern"><title>The Host Pattern</title>
2189 The matching of the host part offers some flexible options: if the
2190 host pattern starts or ends with a dot, it becomes unanchored at that end.
2191 The host pattern is often referred to as domain pattern as it is usually
2192 used to match domain names and not IP addresses.
2198 <term><literal>.example.com</literal></term>
2201 matches any domain with first-level domain <literal>com</literal>
2202 and second-level domain <literal>example</literal>.
2203 For example <literal>www.example.com</literal>,
2204 <literal>example.com</literal> and <literal>foo.bar.baz.example.com</literal>.
2205 Note that it wouldn't match if the second-level domain was <literal>another-example</literal>.
2210 <term><literal>www.</literal></term>
2213 matches any domain that <emphasis>STARTS</emphasis> with
2214 <literal>www.</literal> (It also matches the domain
2215 <literal>www</literal> but most of the time that doesn't matter.)
2220 <term><literal>.example.</literal></term>
2223 matches any domain that <emphasis>CONTAINS</emphasis> <literal>.example.</literal>.
2224 And, by the way, also included would be any files or documents that exist
2225 within that domain since no path limitations are specified. (Correctly
2226 speaking: It matches any FQDN that contains <literal>example</literal> as
2227 a domain.) This might be <literal>www.example.com</literal>,
2228 <literal>news.example.de</literal>, or
2229 <literal>www.example.net/cgi/testing.pl</literal> for instance. All these
2237 Additionally, there are wild-cards that you can use in the domain names
2238 themselves. These work similarly to shell globbing type wild-cards:
2239 <quote>*</quote> represents zero or more arbitrary characters (this is
2241 <ulink url="http://en.wikipedia.org/wiki/Regular_expressions"><quote>Regular
2242 Expression</quote></ulink> based syntax of <quote>.*</quote>),
2243 <quote>?</quote> represents any single character (this is equivalent to the
2244 regular expression syntax of a simple <quote>.</quote>), and you can define
2245 <quote>character classes</quote> in square brackets which is similar to
2246 the same regular expression technique. All of this can be freely mixed:
2251 <term><literal>ad*.example.com</literal></term>
2254 matches <quote>adserver.example.com</quote>,
2255 <quote>ads.example.com</quote>, etc but not <quote>sfads.example.com</quote>
2260 <term><literal>*ad*.example.com</literal></term>
2263 matches all of the above, and then some.
2268 <term><literal>.?pix.com</literal></term>
2271 matches <literal>www.ipix.com</literal>,
2272 <literal>pictures.epix.com</literal>, <literal>a.b.c.d.e.upix.com</literal> etc.
2277 <term><literal>www[1-9a-ez].example.c*</literal></term>
2280 matches <literal>www1.example.com</literal>,
2281 <literal>www4.example.cc</literal>, <literal>wwwd.example.cy</literal>,
2282 <literal>wwwz.example.com</literal> etc., but <emphasis>not</emphasis>
2283 <literal>wwww.example.com</literal>.
2290 While flexible, this is not the sophistication of full regular expression based syntax.
2295 <!-- ~ End section ~ -->
2298 <!-- ~~~~~ New section ~~~~~ -->
2299 <sect3 id="path-pattern"><title>The Path Pattern</title>
2302 <application>Privoxy</application> uses <quote>modern</quote> POSIX 1003.2
2303 <ulink url="http://en.wikipedia.org/wiki/Regular_expressions"><quote>Regular
2304 Expressions</quote></ulink> for matching the path portion (after the slash),
2305 and is thus more flexible.
2309 There is an <link linkend="regex">Appendix</link> with a brief quick-start into regular
2310 expressions, you also might want to have a look at your operating system's documentation
2311 on regular expressions (try <literal>man re_format</literal>).
2315 Note that the path pattern is automatically left-anchored at the <quote>/</quote>,
2316 i.e. it matches as if it would start with a <quote>^</quote> (regular expression speak
2317 for the beginning of a line).
2321 Please also note that matching in the path is <emphasis>CASE INSENSITIVE</emphasis>
2322 by default, but you can switch to case sensitive at any point in the pattern by using the
2323 <quote>(?-i)</quote> switch: <literal>www.example.com/(?-i)PaTtErN.*</literal> will match
2324 only documents whose path starts with <literal>PaTtErN</literal> in
2325 <emphasis>exactly</emphasis> this capitalization.
2330 <term><literal>.example.com/.*</literal></term>
2333 Is equivalent to just <quote>.example.com</quote>, since any documents
2334 within that domain are matched with or without the <quote>.*</quote>
2335 regular expression. This is redundant
2340 <term><literal>.example.com/.*/index.html$</literal></term>
2343 Will match any page in the domain of <quote>example.com</quote> that is
2344 named <quote>index.html</quote>, and that is part of some path. For
2345 example, it matches <quote>www.example.com/testing/index.html</quote> but
2346 NOT <quote>www.example.com/index.html</quote> because the regular
2347 expression called for at least two <quote>/'s</quote>, thus the path
2348 requirement. It also would match
2349 <quote>www.example.com/testing/index_html</quote>, because of the
2350 special meta-character <quote>.</quote>.
2355 <term><literal>.example.com/(.*/)?index\.html$</literal></term>
2358 This regular expression is conditional so it will match any page
2359 named <quote>index.html</quote> regardless of path which in this case can
2360 have one or more <quote>/'s</quote>. And this one must contain exactly
2361 <quote>.html</quote> (and end with that!).
2366 <term><literal>.example.com/(.*/)(ads|banners?|junk)</literal></term>
2369 This regular expression will match any path of <quote>example.com</quote>
2370 that contains any of the words <quote>ads</quote>, <quote>banner</quote>,
2371 <quote>banners</quote> (because of the <quote>?</quote>) or <quote>junk</quote>.
2372 The path does not have to end in these words, just contain them.
2373 The path has to contain at least two slashes (including the one at the beginning).
2378 <term><literal>.example.com/(.*/)(ads|banners?|junk)/.*\.(jpe?g|gif|png)$</literal></term>
2381 This is very much the same as above, except now it must end in either
2382 <quote>.jpg</quote>, <quote>.jpeg</quote>, <quote>.gif</quote> or <quote>.png</quote>. So this
2383 one is limited to common image formats.
2390 There are many, many good examples to be found in <filename>default.action</filename>,
2391 and more tutorials below in <link linkend="regex">Appendix on regular expressions</link>.
2396 <!-- ~ End section ~ -->
2399 <!-- ~~~~~ New section ~~~~~ -->
2400 <sect3 id="tag-pattern"><title>The Request Tag Pattern</title>
2403 Request tag patterns are used to change the applying actions based on the
2404 request's tags. Tags can be created based on HTTP headers with either
2405 the <link linkend="CLIENT-HEADER-TAGGER">client-header-tagger</link>
2406 or the <link linkend="SERVER-HEADER-TAGGER">server-header-tagger</link> action.
2410 Request tag patterns have to start with <quote>TAG:</quote>, so &my-app;
2411 can tell them apart from other patterns. Everything after the colon
2412 including white space, is interpreted as a regular expression with
2413 path pattern syntax, except that tag patterns aren't left-anchored
2414 automatically (&my-app; doesn't silently add a <quote>^</quote>,
2415 you have to do it yourself if you need it).
2419 To match all requests that are tagged with <quote>foo</quote>
2420 your pattern line should be <quote>TAG:^foo$</quote>,
2421 <quote>TAG:foo</quote> would work as well, but it would also
2422 match requests whose tags contain <quote>foo</quote> somewhere.
2423 <quote>TAG: foo</quote> wouldn't work as it requires white space.
2427 Sections can contain URL and request tag patterns at the same time,
2428 but request tag patterns are checked after the URL patterns and thus
2429 always overrule them, even if they are located before the URL patterns.
2433 Once a new request tag is added, Privoxy checks right away if it's matched by one
2434 of the request tag patterns and updates the action settings accordingly. As a result
2435 request tags can be used to activate other tagger actions, as long as these other
2436 taggers look for headers that haven't already be parsed.
2440 For example you could tag client requests which use the
2441 <literal>POST</literal> method,
2442 then use this tag to activate another tagger that adds a tag if cookies
2443 are sent, and then use a block action based on the cookie tag. This allows
2444 the outcome of one action, to be input into a subsequent action. However if
2445 you'd reverse the position of the described taggers, and activated the
2446 method tagger based on the cookie tagger, no method tags would be created.
2447 The method tagger would look for the request line, but at the time
2448 the cookie tag is created, the request line has already been parsed.
2452 While this is a limitation you should be aware of, this kind of
2453 indirection is seldom needed anyway and even the example doesn't
2454 make too much sense.
2459 <!-- ~~~~~ New section ~~~~~ -->
2460 <sect3 id="negative-tag-patterns"><title>The Negative Request Tag Patterns</title>
2463 To match requests that do not have a certain request tag, specify a negative tag pattern
2464 by prefixing the tag pattern line with either <quote>NO-REQUEST-TAG:</quote>
2465 or <quote>NO-RESPONSE-TAG:</quote> instead of <quote>TAG:</quote>.
2469 Negative request tag patterns created with <quote>NO-REQUEST-TAG:</quote> are checked
2470 after all client headers are scanned, the ones created with <quote>NO-RESPONSE-TAG:</quote>
2471 are checked after all server headers are scanned. In both cases all the created
2472 tags are considered.
2476 <!-- ~~~~~ New section ~~~~~ -->
2477 <sect3 id="client-tag-pattern"><title>The Client Tag Pattern</title>
2479 <!-- XXX: This section contains duplicates content from the
2480 client-specific-tag documentation. -->
2484 This is an experimental feature. The syntax is likely to change in future versions.
2489 Client tag patterns are not set based on HTTP headers but based on
2490 the client's IP address. Users can enable them themselves, but the
2491 Privoxy admin controls which tags are available and what their effect
2496 After a client-specific tag has been defined with the
2497 <link linkend="client-specific-tag">client-specific-tag</link>,
2498 directive, action sections can be activated based on the tag by using a
2499 CLIENT-TAG pattern. The CLIENT-TAG pattern is evaluated at the same priority
2500 as URL patterns, as a result the last matching pattern wins. Tags that
2501 are created based on client or server headers are evaluated later on
2502 and can overrule CLIENT-TAG and URL patterns!
2505 The tag is set for all requests that come from clients that requested
2506 it to be set. Note that "clients" are differentiated by IP address,
2507 if the IP address changes the tag has to be requested again.
2510 Clients can request tags to be set by using the CGI interface <ulink
2511 url="http://config.privoxy.org/client-tags">http://config.privoxy.org/client-tags</ulink>.
2519 # If the admin defined the client-specific-tag circumvent-blocks,
2520 # and the request comes from a client that previously requested
2521 # the tag to be set, overrule all previous +block actions that
2522 # are enabled based on URL to CLIENT-TAG patterns.
2524 CLIENT-TAG:^circumvent-blocks$
2526 # This section is not overruled because it's located after
2528 {+block{Nobody is supposed to request this.}}
2529 example.org/blocked-example-page</screen>
2535 <!-- ~ End section ~ -->
2538 <!-- ~~~~~ New section ~~~~~ -->
2540 <sect2 id="actions">
2541 <title>Actions</title>
2543 All actions are disabled by default, until they are explicitly enabled
2544 somewhere in an actions file. Actions are turned on if preceded with a
2545 <quote>+</quote>, and turned off if preceded with a <quote>-</quote>. So a
2546 <literal>+action</literal> means <quote>do that action</quote>, e.g.
2547 <literal>+block</literal> means <quote>please block URLs that match the
2548 following patterns</quote>, and <literal>-block</literal> means <quote>don't
2549 block URLs that match the following patterns, even if <literal>+block</literal>
2550 previously applied.</quote>
2554 Again, actions are invoked by placing them on a line, enclosed in curly braces and
2555 separated by whitespace, like in
2556 <literal>{+some-action -some-other-action{some-parameter}}</literal>,
2557 followed by a list of URL patterns, one per line, to which they apply.
2558 Together, the actions line and the following pattern lines make up a section
2559 of the actions file.
2563 Actions fall into three categories:
2569 Boolean, i.e the action can only be <quote>enabled</quote> or
2570 <quote>disabled</quote>. Syntax:
2573 +<replaceable class="function">name</replaceable> # enable action <replaceable class="parameter">name</replaceable>
2574 -<replaceable class="function">name</replaceable> # disable action <replaceable class="parameter">name</replaceable></screen>
2576 Example: <literal>+handle-as-image</literal>
2583 Parameterized, where some value is required in order to enable this type of action.
2587 +<replaceable class="function">name</replaceable>{<replaceable class="parameter">param</replaceable>} # enable action and set parameter to <replaceable class="parameter">param</replaceable>,
2588 # overwriting parameter from previous match if necessary
2589 -<replaceable class="function">name</replaceable> # disable action. The parameter can be omitted</screen>
2591 Note that if the URL matches multiple positive forms of a parameterized action,
2592 the last match wins, i.e. the params from earlier matches are simply ignored.
2595 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>
2601 Multi-value. These look exactly like parameterized actions,
2602 but they behave differently: If the action applies multiple times to the
2603 same URL, but with different parameters, <emphasis>all</emphasis> the parameters
2604 from <emphasis>all</emphasis> matches are remembered. This is used for actions
2605 that can be executed for the same request repeatedly, like adding multiple
2606 headers, or filtering through multiple filters. Syntax:
2609 +<replaceable class="function">name</replaceable>{<replaceable class="parameter">param</replaceable>} # enable action and add <replaceable class="parameter">param</replaceable> to the list of parameters
2610 -<replaceable class="function">name</replaceable>{<replaceable class="parameter">param</replaceable>} # remove the parameter <replaceable class="parameter">param</replaceable> from the list of parameters
2611 # If it was the last one left, disable the action.
2612 <replaceable class="parameter">-name</replaceable> # disable this action completely and remove all parameters from the list</screen>
2614 Examples: <literal>+add-header{X-Fun-Header: Some text}</literal> and
2615 <literal>+filter{html-annoyances}</literal>
2622 If nothing is specified in any actions file, no <quote>actions</quote> are
2623 taken. So in this case <application>Privoxy</application> would just be a
2624 normal, non-blocking, non-filtering proxy. You must specifically enable the
2625 privacy and blocking features you need (although the provided default actions
2626 files will give a good starting point).
2630 Later defined action sections always over-ride earlier ones of the same type.
2631 So exceptions to any rules you make, should come in the latter part of the file (or
2632 in a file that is processed later when using multiple actions files such
2633 as <filename>user.action</filename>). For multi-valued actions, the actions
2634 are applied in the order they are specified. Actions files are processed in
2635 the order they are defined in <filename>config</filename> (the default
2636 installation has three actions files). It also quite possible for any given
2637 URL to match more than one <quote>pattern</quote> (because of wildcards and
2638 regular expressions), and thus to trigger more than one set of actions! Last
2642 <!-- start actions listing -->
2644 The list of valid <application>Privoxy</application> actions are:
2648 <!-- ********************************************************** -->
2649 <!-- Please note the below defined actions use id's that are -->
2650 <!-- probably linked from other places, so please don't change. -->
2652 <!-- ********************************************************** -->
2655 <!-- ~~~~~ New section ~~~~~ -->
2657 <sect3 renderas="sect4" id="add-header">
2658 <title>add-header</title>
2662 <term>Typical use:</term>
2664 <para>Confuse log analysis, custom applications</para>
2669 <term>Effect:</term>
2672 Sends a user defined HTTP header to the web server.
2679 <!-- boolean, parameterized, Multi-value -->
2681 <para>Multi-value.</para>
2686 <term>Parameter:</term>
2689 Any string value is possible. Validity of the defined HTTP headers is not checked.
2690 It is recommended that you use the <quote><literal>X-</literal></quote> prefix
2700 This action may be specified multiple times, in order to define multiple
2701 headers. This is rarely needed for the typical user. If you don't know what
2702 <quote>HTTP headers</quote> are, you definitely don't need to worry about this
2706 Headers added by this action are not modified by other actions.
2712 <term>Example usage:</term>
2714 <screen># Add a DNT ("Do not track") header to all requests,
2715 # event to those that already have one.
2717 # This is just an example, not a recommendation.
2719 # There is no reason to believe that user-tracking websites care
2720 # about the DNT header and depending on the User-Agent, adding the
2721 # header may make user-tracking easier.
2722 {+add-header{DNT: 1}}
2730 <!-- ~~~~~ New section ~~~~~ -->
2731 <sect3 renderas="sect4" id="block">
2732 <title>block</title>
2736 <term>Typical use:</term>
2738 <para>Block ads or other unwanted content</para>
2743 <term>Effect:</term>
2746 Requests for URLs to which this action applies are blocked, i.e. the
2747 requests are trapped by &my-app; and the requested URL is never retrieved,
2748 but is answered locally with a substitute page or image, as determined by
2750 linkend="handle-as-image">handle-as-image</link></literal>,
2752 linkend="set-image-blocker">set-image-blocker</link></literal>, and
2754 linkend="handle-as-empty-document">handle-as-empty-document</link></literal> actions.
2762 <!-- boolean, parameterized, Multi-value -->
2764 <para>Parameterized.</para>
2769 <term>Parameter:</term>
2771 <para>A block reason that should be given to the user.</para>
2779 <application>Privoxy</application> sends a special <quote>BLOCKED</quote> page
2780 for requests to blocked pages. This page contains the block reason given as
2781 parameter, a link to find out why the block action applies, and a click-through
2782 to the blocked content (the latter only if the force feature is available and
2786 A very important exception occurs if <emphasis>both</emphasis>
2787 <literal>block</literal> and <literal><link linkend="handle-as-image">handle-as-image</link></literal>,
2788 apply to the same request: it will then be replaced by an image. If
2789 <literal><link linkend="set-image-blocker">set-image-blocker</link></literal>
2790 (see below) also applies, the type of image will be determined by its parameter,
2791 if not, the standard checkerboard pattern is sent.
2794 It is important to understand this process, in order
2795 to understand how <application>Privoxy</application> deals with
2796 ads and other unwanted content. Blocking is a core feature, and one
2797 upon which various other features depend.
2800 The <literal><link linkend="filter">filter</link></literal>
2801 action can perform a very similar task, by <quote>blocking</quote>
2802 banner images and other content through rewriting the relevant URLs in the
2803 document's HTML source, so they don't get requested in the first place.
2804 Note that this is a totally different technique, and it's easy to confuse the two.
2810 <term>Example usage (section):</term>
2812 <screen>{+block{No nasty stuff for you.}}
2813 # Block and replace with "blocked" page
2814 .nasty-stuff.example.com
2816 {+block{Doubleclick banners.} +handle-as-image}
2817 # Block and replace with image
2821 {+block{Layered ads.} +handle-as-empty-document}
2822 # Block and then ignore
2823 adserver.example.net/.*\.js$</screen>
2832 <!-- ~~~~~ New section ~~~~~ -->
2833 <sect3 renderas="sect4" id="change-x-forwarded-for">
2834 <title>change-x-forwarded-for</title>
2838 <term>Typical use:</term>
2840 <para>Improve privacy by not forwarding the source of the request in the HTTP headers.</para>
2845 <term>Effect:</term>
2848 Deletes the <quote>X-Forwarded-For:</quote> HTTP header from the client request,
2856 <!-- Boolean, Parameterized, Multi-value -->
2858 <para>Parameterized.</para>
2863 <term>Parameter:</term>
2867 <para><quote>block</quote> to delete the header.</para>
2871 <quote>add</quote> to create the header (or append
2872 the client's IP address to an already existing one).
2883 It is safe and recommended to use <literal>block</literal>.
2886 Forwarding the source address of the request may make
2887 sense in some multi-user setups but is also a privacy risk.
2892 <term>Example usage:</term>
2894 <screen>+change-x-forwarded-for{block}</screen>
2900 <!-- ~~~~~ New section ~~~~~ -->
2901 <sect3 renderas="sect4" id="client-header-filter">
2902 <title>client-header-filter</title>
2906 <term>Typical use:</term>
2909 Rewrite or remove single client headers.
2915 <term>Effect:</term>
2918 All client headers to which this action applies are filtered on-the-fly through
2919 the specified regular expression based substitutions.
2926 <!-- boolean, parameterized, Multi-value -->
2928 <para>Multi-value.</para>
2933 <term>Parameter:</term>
2936 The name of a client-header filter, as defined in one of the
2937 <link linkend="filter-file">filter files</link>.
2946 Client-header filters are applied to each header on its own, not to
2947 all at once. This makes it easier to diagnose problems, but on the downside
2948 you can't write filters that only change header x if header y's value is z.
2949 You can do that by using tags though.
2952 Client-header filters are executed after the other header actions have finished
2953 and use their output as input.
2956 If the request URI gets changed, &my-app; will detect that and use the new
2957 one. This can be used to rewrite the request destination behind the client's
2958 back, for example to specify a Tor exit relay for certain requests.
2961 Please refer to the <link linkend="filter-file">filter file chapter</link>
2962 to learn which client-header filters are available by default, and how to
2970 <term>Example usage (section):</term>
2973 # Hide Tor exit notation in Host and Referer Headers
2974 {+client-header-filter{hide-tor-exit-notation}}
2984 <!-- ~~~~~ New section ~~~~~ -->
2985 <sect3 renderas="sect4" id="client-header-tagger">
2986 <title>client-header-tagger</title>
2990 <term>Typical use:</term>
2993 Block requests based on their headers.
2999 <term>Effect:</term>
3002 Client headers to which this action applies are filtered on-the-fly through
3003 the specified regular expression based substitutions, the result is used as
3011 <!-- boolean, parameterized, Multi-value -->
3013 <para>Multi-value.</para>
3018 <term>Parameter:</term>
3021 The name of a client-header tagger, as defined in one of the
3022 <link linkend="filter-file">filter files</link>.
3031 Client-header taggers are applied to each header on its own,
3032 and as the header isn't modified, each tagger <quote>sees</quote>
3036 Client-header taggers are the first actions that are executed
3037 and their tags can be used to control every other action.
3043 <term>Example usage (section):</term>
3046 # Tag every request with the User-Agent header
3047 {+client-header-tagger{user-agent}}
3050 # Tagging itself doesn't change the action
3051 # settings, sections with TAG patterns do:
3053 # If it's a download agent, use a different forwarding proxy,
3054 # show the real User-Agent and make sure resume works.
3055 {+forward-override{forward-socks5 10.0.0.2:2222 .} \
3056 -hide-if-modified-since \
3057 -overwrite-last-modified \
3062 TAG:^User-Agent: NetBSD-ftp/
3063 TAG:^User-Agent: Novell ZYPP Installer
3064 TAG:^User-Agent: RPM APT-HTTP/
3065 TAG:^User-Agent: fetch libfetch/
3066 TAG:^User-Agent: Ubuntu APT-HTTP/
3067 TAG:^User-Agent: MPlayer/
3071 # Tag all requests with the Range header set
3072 {+client-header-tagger{range-requests}}
3075 # Disable filtering for the tagged requests.
3077 # With filtering enabled Privoxy would remove the Range headers
3078 # to be able to filter the whole response. The downside is that
3079 # it prevents clients from resuming downloads or skipping over
3080 # parts of multimedia files.
3081 {-filter -deanimate-gifs}
3086 # Tag all requests with the client IP address
3088 # (Technically the client IP address isn't included in the
3089 # client headers but client-header taggers can set it anyway.
3090 # For details see the tagger in default.filter)
3091 {+client-header-tagger{client-ip-address}}
3094 # Change forwarding settings for requests coming from address 10.0.0.1
3095 {+forward-override{forward-socks5 127.0.1.2:2222 .}}
3096 TAG:^IP-ADDRESS: 10\.0\.0\.1$
3105 <!-- ~~~~~ New section ~~~~~ -->
3106 <sect3 renderas="sect4" id="content-type-overwrite">
3107 <title>content-type-overwrite</title>
3111 <term>Typical use:</term>
3113 <para>Stop useless download menus from popping up, or change the browser's rendering mode</para>
3118 <term>Effect:</term>
3121 Replaces the <quote>Content-Type:</quote> HTTP server header.
3128 <!-- Boolean, Parameterized, Multi-value -->
3130 <para>Parameterized.</para>
3135 <term>Parameter:</term>
3147 The <quote>Content-Type:</quote> HTTP server header is used by the
3148 browser to decide what to do with the document. The value of this
3149 header can cause the browser to open a download menu instead of
3150 displaying the document by itself, even if the document's format is
3151 supported by the browser.
3154 The declared content type can also affect which rendering mode
3155 the browser chooses. If XHTML is delivered as <quote>text/html</quote>,
3156 many browsers treat it as yet another broken HTML document.
3157 If it is send as <quote>application/xml</quote>, browsers with
3158 XHTML support will only display it, if the syntax is correct.
3161 If you see a web site that proudly uses XHTML buttons, but sets
3162 <quote>Content-Type: text/html</quote>, you can use &my-app;
3163 to overwrite it with <quote>application/xml</quote> and validate
3164 the web master's claim inside your XHTML-supporting browser.
3165 If the syntax is incorrect, the browser will complain loudly.
3168 You can also go the opposite direction: if your browser prints
3169 error messages instead of rendering a document falsely declared
3170 as XHTML, you can overwrite the content type with
3171 <quote>text/html</quote> and have it rendered as broken HTML document.
3174 By default <literal>content-type-overwrite</literal> only replaces
3175 <quote>Content-Type:</quote> headers that look like some kind of text.
3176 If you want to overwrite it unconditionally, you have to combine it with
3177 <literal><link linkend="force-text-mode">force-text-mode</link></literal>.
3178 This limitation exists for a reason, think twice before circumventing it.
3181 Most of the time it's easier to replace this action with a custom
3182 <literal><link linkend="server-header-filter">server-header filter</link></literal>.
3183 It allows you to activate it for every document of a certain site and it will still
3184 only replace the content types you aimed at.
3187 Of course you can apply <literal>content-type-overwrite</literal>
3188 to a whole site and then make URL based exceptions, but it's a lot
3189 more work to get the same precision.
3195 <term>Example usage (sections):</term>
3197 <screen># Check if www.example.net/ really uses valid XHTML
3198 { +content-type-overwrite{application/xml} }
3201 # but leave the content type unmodified if the URL looks like a style sheet
3202 {-content-type-overwrite}
3203 www.example.net/.*\.css$
3204 www.example.net/.*style
3212 <!-- ~~~~~ New section ~~~~~ -->
3213 <sect3 renderas="sect4" id="crunch-client-header">
3217 <title>crunch-client-header</title>
3221 <term>Typical use:</term>
3223 <para>Remove a client header <application>Privoxy</application> has no dedicated action for.</para>
3228 <term>Effect:</term>
3231 Deletes every header sent by the client that contains the string the user supplied as parameter.
3238 <!-- Boolean, Parameterized, Multi-value -->
3240 <para>Parameterized.</para>
3245 <term>Parameter:</term>
3257 This action allows you to block client headers for which no dedicated
3258 <application>Privoxy</application> action exists.
3259 <application>Privoxy</application> will remove every client header that
3260 contains the string you supplied as parameter.
3263 Regular expressions are <emphasis>not supported</emphasis> and you can't
3264 use this action to block different headers in the same request, unless
3265 they contain the same string.
3268 <literal>crunch-client-header</literal> is only meant for quick tests.
3269 If you have to block several different headers, or only want to modify
3270 parts of them, you should use a
3271 <literal><link linkend="client-header-filter">client-header filter</link></literal>.
3275 Don't block any header without understanding the consequences.
3282 <term>Example usage (section):</term>
3284 <screen># Block the non-existent "Privacy-Violation:" client header
3285 { +crunch-client-header{Privacy-Violation:} }
3294 <!-- ~~~~~ New section ~~~~~ -->
3295 <sect3 renderas="sect4" id="crunch-if-none-match">
3296 <title>crunch-if-none-match</title>
3302 <term>Typical use:</term>
3304 <para>Prevent yet another way to track the user's steps between sessions.</para>
3309 <term>Effect:</term>
3312 Deletes the <quote>If-None-Match:</quote> HTTP client header.
3319 <!-- Boolean, Parameterized, Multi-value -->
3321 <para>Boolean.</para>
3326 <term>Parameter:</term>
3338 Removing the <quote>If-None-Match:</quote> HTTP client header
3339 is useful for filter testing, where you want to force a real
3340 reload instead of getting status code <quote>304</quote> which
3341 would cause the browser to use a cached copy of the page.
3344 It is also useful to make sure the header isn't used as a cookie
3345 replacement (unlikely but possible).
3348 Blocking the <quote>If-None-Match:</quote> header shouldn't cause any
3349 caching problems, as long as the <quote>If-Modified-Since:</quote> header
3350 isn't blocked or missing as well.
3353 It is recommended to use this action together with
3354 <literal><link linkend="hide-if-modified-since">hide-if-modified-since</link></literal>
3356 <literal><link linkend="overwrite-last-modified">overwrite-last-modified</link></literal>.
3362 <term>Example usage (section):</term>
3364 <screen># Let the browser revalidate cached documents but don't
3365 # allow the server to use the revalidation headers for user tracking.
3366 {+hide-if-modified-since{-60} \
3367 +overwrite-last-modified{randomize} \
3368 +crunch-if-none-match}
3377 <!-- ~~~~~ New section ~~~~~ -->
3378 <sect3 renderas="sect4" id="crunch-incoming-cookies">
3379 <title>crunch-incoming-cookies</title>
3383 <term>Typical use:</term>
3386 Prevent the web server from setting HTTP cookies on your system
3392 <term>Effect:</term>
3395 Deletes any <quote>Set-Cookie:</quote> HTTP headers from server replies.
3402 <!-- Boolean, Parameterized, Multi-value -->
3404 <para>Boolean.</para>
3409 <term>Parameter:</term>
3421 This action is only concerned with <emphasis>incoming</emphasis> HTTP cookies. For
3422 <emphasis>outgoing</emphasis> HTTP cookies, use
3423 <literal><link linkend="crunch-outgoing-cookies">crunch-outgoing-cookies</link></literal>.
3424 Use <emphasis>both</emphasis> to disable HTTP cookies completely.
3427 It makes <emphasis>no sense at all</emphasis> to use this action in conjunction
3428 with the <literal><link linkend="session-cookies-only">session-cookies-only</link></literal> action,
3429 since it would prevent the session cookies from being set. See also
3430 <literal><link linkend="filter-content-cookies">filter-content-cookies</link></literal>.
3436 <term>Example usage:</term>
3438 <screen>+crunch-incoming-cookies</screen>
3445 <!-- ~~~~~ New section ~~~~~ -->
3446 <sect3 renderas="sect4" id="crunch-server-header">
3447 <title>crunch-server-header</title>
3453 <term>Typical use:</term>
3455 <para>Remove a server header <application>Privoxy</application> has no dedicated action for.</para>
3460 <term>Effect:</term>
3463 Deletes every header sent by the server that contains the string the user supplied as parameter.
3470 <!-- Boolean, Parameterized, Multi-value -->
3472 <para>Parameterized.</para>
3477 <term>Parameter:</term>
3489 This action allows you to block server headers for which no dedicated
3490 <application>Privoxy</application> action exists. <application>Privoxy</application>
3491 will remove every server header that contains the string you supplied as parameter.
3494 Regular expressions are <emphasis>not supported</emphasis> and you can't
3495 use this action to block different headers in the same request, unless
3496 they contain the same string.
3499 <literal>crunch-server-header</literal> is only meant for quick tests.
3500 If you have to block several different headers, or only want to modify
3501 parts of them, you should use a custom
3502 <literal><link linkend="server-header-filter">server-header filter</link></literal>.
3506 Don't block any header without understanding the consequences.
3513 <term>Example usage (section):</term>
3515 <screen># Crunch server headers that try to prevent caching
3516 { +crunch-server-header{no-cache} }
3525 <!-- ~~~~~ New section ~~~~~ -->
3526 <sect3 renderas="sect4" id="crunch-outgoing-cookies">
3527 <title>crunch-outgoing-cookies</title>
3531 <term>Typical use:</term>
3534 Prevent the web server from reading any HTTP cookies from your system
3540 <term>Effect:</term>
3543 Deletes any <quote>Cookie:</quote> HTTP headers from client requests.
3550 <!-- Boolean, Parameterized, Multi-value -->
3552 <para>Boolean.</para>
3557 <term>Parameter:</term>
3569 This action is only concerned with <emphasis>outgoing</emphasis> HTTP cookies. For
3570 <emphasis>incoming</emphasis> HTTP cookies, use
3571 <literal><link linkend="crunch-incoming-cookies">crunch-incoming-cookies</link></literal>.
3572 Use <emphasis>both</emphasis> to disable HTTP cookies completely.
3575 It makes <emphasis>no sense at all</emphasis> to use this action in conjunction
3576 with the <literal><link linkend="session-cookies-only">session-cookies-only</link></literal> action,
3577 since it would prevent the session cookies from being read.
3583 <term>Example usage:</term>
3585 <screen>+crunch-outgoing-cookies</screen>
3593 <!-- ~~~~~ New section ~~~~~ -->
3594 <sect3 renderas="sect4" id="deanimate-gifs">
3595 <title>deanimate-gifs</title>
3599 <term>Typical use:</term>
3601 <para>Stop those annoying, distracting animated GIF images.</para>
3606 <term>Effect:</term>
3609 De-animate GIF animations, i.e. reduce them to their first or last image.
3616 <!-- boolean, parameterized, Multi-value -->
3618 <para>Parameterized.</para>
3623 <term>Parameter:</term>
3626 <quote>last</quote> or <quote>first</quote>
3635 This will also shrink the images considerably (in bytes, not pixels!). If
3636 the option <quote>first</quote> is given, the first frame of the animation
3637 is used as the replacement. If <quote>last</quote> is given, the last
3638 frame of the animation is used instead, which probably makes more sense for
3639 most banner animations, but also has the risk of not showing the entire
3640 last frame (if it is only a delta to an earlier frame).
3643 You can safely use this action with patterns that will also match non-GIF
3644 objects, because no attempt will be made at anything that doesn't look like
3651 <term>Example usage:</term>
3653 <screen>+deanimate-gifs{last}</screen>
3660 <!-- ~~~~~ New section ~~~~~ -->
3661 <sect3 renderas="sect4" id="delay-response">
3662 <title>delay-response</title>
3666 <term>Typical use:</term>
3668 <para>Delay responses to the client to reduce the load</para>
3673 <term>Effect:</term>
3676 Delays responses to the client by sending the response in ca. 10 byte chunks.
3683 <!-- boolean, parameterized, Multi-value -->
3685 <para>Parameterized.</para>
3690 <term>Parameter:</term>
3693 <quote>Number of milliseconds</quote>
3702 Sometimes when JavaScript code is used to fetch advertisements
3703 it doesn't respect Privoxy's blocks and retries to fetch the
3704 same resource again causing unnecessary load on the client.
3707 This action delays responses to the client and can be combined
3708 with <literal><link linkend="block">blocks</link></literal>
3709 to slow down the JavaScript code, thus reducing
3710 the load on the client.
3713 When used without <literal><link linkend="block">blocks</link></literal>
3714 the action can also be used to simulate a slow internet connection.
3720 <term>Example usage:</term>
3722 <screen>+delay-response{100}</screen>
3729 <!-- ~~~~~ New section ~~~~~ -->
3730 <sect3 renderas="sect4" id="downgrade-http-version">
3731 <title>downgrade-http-version</title>
3735 <term>Typical use:</term>
3737 <para>Work around (very rare) problems with HTTP/1.1</para>
3742 <term>Effect:</term>
3745 Downgrades HTTP/1.1 client requests and server replies to HTTP/1.0.
3752 <!-- boolean, parameterized, Multi-value -->
3754 <para>Boolean.</para>
3759 <term>Parameter:</term>
3771 This is a left-over from the time when <application>Privoxy</application>
3772 didn't support important HTTP/1.1 features well. It is left here for the
3773 unlikely case that you experience HTTP/1.1-related problems with some server
3777 Note that enabling this action is only a workaround. It should not
3778 be enabled for sites that work without it. While it shouldn't break
3779 any pages, it has an (usually negative) performance impact.
3782 If you come across a site where enabling this action helps, please report it,
3783 so the cause of the problem can be analyzed. If the problem turns out to be
3784 caused by a bug in <application>Privoxy</application> it should be
3785 fixed so the following release works without the work around.
3791 <term>Example usage (section):</term>
3793 <screen>{+downgrade-http-version}
3794 problem-host.example.com</screen>
3801 <!-- ~~~~~ New section ~~~~~ -->
3802 <sect3 renderas="sect4" id="external-filter">
3803 <title>external-filter</title>
3807 <term>Typical use:</term>
3809 <para>Modify content using a programming language of your choice.</para>
3814 <term>Effect:</term>
3817 All instances of text-based type, most notably HTML and JavaScript, to which
3818 this action applies, can be filtered on-the-fly through the specified external
3820 By default plain text documents are exempted from filtering, because web
3821 servers often use the <literal>text/plain</literal> MIME type for all files
3822 whose type they don't know.)
3829 <!-- boolean, parameterized, Multi-value -->
3831 <para>Multi-value.</para>
3836 <term>Parameter:</term>
3839 The name of an external content filter, as defined in the
3840 <link linkend="filter-file">filter file</link>.
3841 External filters can be defined in one or more files as defined by the
3842 <literal><link linkend="filterfile">filterfile</link></literal>
3843 option in the <link linkend="config">config file</link>.
3846 When used in its negative form,
3847 and without parameters, <emphasis>all</emphasis> filtering with external
3848 filters is completely disabled.
3857 External filters are scripts or programs that can modify the content in
3858 case common <literal><link linkend="filter">filters</link></literal>
3859 aren't powerful enough. With the exception that this action doesn't
3860 use pcrs-based filters, the notes in the
3861 <literal><link linkend="filter">filter</link></literal> section apply.
3865 Currently external filters are executed with &my-app;'s privileges.
3866 Only use external filters you understand and trust.
3870 This feature is experimental, the <literal><link
3871 linkend="external-filter-syntax">syntax</link></literal>
3872 may change in the future.
3879 <term>Example usage:</term>
3881 <screen>+external-filter{fancy-filter}</screen>
3887 <!-- ~~~~~ New section ~~~~~ -->
3888 <sect3 renderas="sect4" id="fast-redirects">
3889 <title>fast-redirects</title>
3893 <term>Typical use:</term>
3895 <para>Fool some click-tracking scripts and speed up indirect links.</para>
3900 <term>Effect:</term>
3903 Detects redirection URLs and redirects the browser without contacting
3904 the redirection server first.
3911 <!-- boolean, parameterized, Multi-value -->
3913 <para>Parameterized.</para>
3918 <term>Parameter:</term>
3923 <quote>simple-check</quote> to just search for the string <quote>http://</quote>
3924 to detect redirection URLs.
3929 <quote>check-decoded-url</quote> to decode URLs (if necessary) before searching
3930 for redirection URLs.
3941 Many sites, like yahoo.com, don't just link to other sites. Instead, they
3942 will link to some script on their own servers, giving the destination as a
3943 parameter, which will then redirect you to the final target. URLs
3944 resulting from this scheme typically look like:
3945 <quote>http://www.example.org/click-tracker.cgi?target=http%3a//www.example.net/</quote>.
3948 Sometimes, there are even multiple consecutive redirects encoded in the
3949 URL. These redirections via scripts make your web browsing more traceable,
3950 since the server from which you follow such a link can see where you go
3951 to. Apart from that, valuable bandwidth and time is wasted, while your
3952 browser asks the server for one redirect after the other. Plus, it feeds
3956 This feature is currently not very smart and is scheduled for improvement.
3957 If it is enabled by default, you will have to create some exceptions to
3958 this action. It can lead to failures in several ways:
3961 Not every URLs with other URLs as parameters is evil.
3962 Some sites offer a real service that requires this information to work.
3963 For example a validation service needs to know, which document to validate.
3964 <literal>fast-redirects</literal> assumes that every URL parameter that
3965 looks like another URL is a redirection target, and will always redirect to
3966 the last one. Most of the time the assumption is correct, but if it isn't,
3967 the user gets redirected anyway.
3970 Another failure occurs if the URL contains other parameters after the URL parameter.
3972 <quote>http://www.example.org/?redirect=http%3a//www.example.net/&foo=bar</quote>.
3973 contains the redirection URL <quote>http://www.example.net/</quote>,
3974 followed by another parameter. <literal>fast-redirects</literal> doesn't know that
3975 and will cause a redirect to <quote>http://www.example.net/&foo=bar</quote>.
3976 Depending on the target server configuration, the parameter will be silently ignored
3977 or lead to a <quote>page not found</quote> error. You can prevent this problem by
3978 first using the <literal><link linkend="redirect">redirect</link></literal> action
3979 to remove the last part of the URL, but it requires a little effort.
3982 To detect a redirection URL, <literal>fast-redirects</literal> only
3983 looks for the string <quote>http://</quote>, either in plain text
3984 (invalid but often used) or encoded as <quote>http%3a//</quote>.
3985 Some sites use their own URL encoding scheme, encrypt the address
3986 of the target server or replace it with a database id. In theses cases
3987 <literal>fast-redirects</literal> is fooled and the request reaches the
3988 redirection server where it probably gets logged.
3994 <term>Example usage:</term>
3997 { +fast-redirects{simple-check} }
4000 { +fast-redirects{check-decoded-url} }
4001 another.example.com/testing</screen>
4009 <!-- ~~~~~ New section ~~~~~ -->
4010 <sect3 renderas="sect4" id="filter">
4011 <title>filter</title>
4015 <term>Typical use:</term>
4017 <para>Get rid of HTML and JavaScript annoyances, banner advertisements (by size),
4018 do fun text replacements, add personalized effects, etc.</para>
4023 <term>Effect:</term>
4026 All instances of text-based type, most notably HTML and JavaScript, to which
4027 this action applies, can be filtered on-the-fly through the specified regular
4028 expression based substitutions. (Note: as of version 3.0.3 plain text documents
4029 are exempted from filtering, because web servers often use the
4030 <literal>text/plain</literal> MIME type for all files whose type they don't know.)
4037 <!-- boolean, parameterized, Multi-value -->
4039 <para>Multi-value.</para>
4044 <term>Parameter:</term>
4047 The name of a content filter, as defined in the <link linkend="filter-file">filter file</link>.
4048 Filters can be defined in one or more files as defined by the
4049 <literal><link linkend="filterfile">filterfile</link></literal>
4050 option in the <link linkend="config">config file</link>.
4051 <filename>default.filter</filename> is the collection of filters
4052 supplied by the developers. Locally defined filters should go
4053 in their own file, such as <filename>user.filter</filename>.
4056 When used in its negative form,
4057 and without parameters, <emphasis>all</emphasis> filtering is completely disabled.
4066 For your convenience, there are a number of pre-defined filters available
4067 in the distribution filter file that you can use. See the examples below for
4071 Filtering requires buffering the page content, which may appear to
4072 slow down page rendering since nothing is displayed until all content has
4073 passed the filters. (The total time until the page is completely rendered
4074 doesn't change much, but it may be perceived as slower since the page is
4075 not incrementally displayed.)
4076 This effect will be more noticeable on slower connections.
4079 <quote>Rolling your own</quote>
4080 filters requires a knowledge of
4081 <ulink url="http://en.wikipedia.org/wiki/Regular_expressions"><quote>Regular
4082 Expressions</quote></ulink> and
4083 <ulink url="http://en.wikipedia.org/wiki/Html"><quote>HTML</quote></ulink>.
4084 This is very powerful feature, and potentially very intrusive.
4085 Filters should be used with caution, and where an equivalent
4086 <quote>action</quote> is not available.
4089 The amount of data that can be filtered is limited to the
4090 <literal><link linkend="buffer-limit">buffer-limit</link></literal>
4091 option in the main <link linkend="config">config file</link>. The
4092 default is 4096 KB (4 Megs). Once this limit is exceeded, the buffered
4093 data, and all pending data, is passed through unfiltered.
4096 Inappropriate MIME types, such as zipped files, are not filtered at all.
4097 (Again, only text-based types except plain text). Encrypted SSL data
4098 (from HTTPS servers) cannot be filtered either, since this would violate
4099 the integrity of the secure transaction. In some situations it might
4100 be necessary to protect certain text, like source code, from filtering
4101 by defining appropriate <literal>-filter</literal> exceptions.
4104 Compressed content can't be filtered either, but if &my-app;
4105 is compiled with zlib support and a supported compression algorithm
4106 is used (gzip or deflate), &my-app; can first decompress the content
4110 If you use a &my-app; version without zlib support, but want filtering to work on
4111 as much documents as possible, even those that would normally be sent compressed,
4112 you must use the <literal><link linkend="prevent-compression">prevent-compression</link></literal>
4113 action in conjunction with <literal>filter</literal>.
4116 Content filtering can achieve some of the same effects as the
4117 <literal><link linkend="block">block</link></literal>
4118 action, i.e. it can be used to block ads and banners. But the mechanism
4119 works quite differently. One effective use, is to block ad banners
4120 based on their size (see below), since many of these seem to be somewhat
4124 <link linkend="contact">Feedback</link> with suggestions for new or
4125 improved filters is particularly welcome!
4128 The below list has only the names and a one-line description of each
4129 predefined filter. There are <link linkend="predefined-filters">more
4130 verbose explanations</link> of what these filters do in the <link
4131 linkend="filter-file">filter file chapter</link>.
4137 <term>Example usage (with filters from the distribution <filename>default.filter</filename> file).
4138 See <link linkend="PREDEFINED-FILTERS">the Predefined Filters section</link> for
4139 more explanation on each:</term>
4142 <anchor id="filter-js-annoyances">
4144 <screen>+filter{js-annoyances} # Get rid of particularly annoying JavaScript abuse.</screen>
4146 <anchor id="filter-js-events">
4148 <screen>+filter{js-events} # Kill JavaScript event bindings and timers (Radically destructive! Only for extra nasty sites).</screen>
4150 <anchor id="filter-html-annoyances">
4152 <screen>+filter{html-annoyances} # Get rid of particularly annoying HTML abuse.</screen>
4154 <anchor id="filter-content-cookies">
4156 <screen>+filter{content-cookies} # Kill cookies that come in the HTML or JS content.</screen>
4158 <anchor id="filter-refresh-tags">
4160 <screen>+filter{refresh-tags} # Kill automatic refresh tags if refresh time is larger than 9 seconds.</screen>
4162 <anchor id="filter-unsolicited-popups">
4164 <screen>+filter{unsolicited-popups} # Disable only unsolicited pop-up windows.</screen>
4166 <anchor id="filter-all-popups">
4168 <screen>+filter{all-popups} # Kill all popups in JavaScript and HTML.</screen>
4170 <anchor id="filter-img-reorder">
4172 <screen>+filter{img-reorder} # Reorder attributes in <img> tags to make the banners-by-* filters more effective.</screen>
4174 <anchor id="filter-banners-by-size">
4176 <screen>+filter{banners-by-size} # Kill banners by size.</screen>
4178 <anchor id="filter-banners-by-link">
4180 <screen>+filter{banners-by-link} # Kill banners by their links to known clicktrackers.</screen>
4182 <anchor id="filter-webbugs">
4184 <screen>+filter{webbugs} # Squish WebBugs (1x1 invisible GIFs used for user tracking).</screen>
4186 <anchor id="filter-tiny-textforms">
4188 <screen>+filter{tiny-textforms} # Extend those tiny textareas up to 40x80 and kill the hard wrap.</screen>
4190 <anchor id="filter-jumping-windows">
4192 <screen>+filter{jumping-windows} # Prevent windows from resizing and moving themselves.</screen>
4194 <anchor id="filter-frameset-borders">
4196 <screen>+filter{frameset-borders} # Give frames a border and make them resizable.</screen>
4198 <anchor id="filter-iframes">
4200 <screen>+filter{iframes} # Removes all detected iframes. Should only be enabled for individual sites.</screen>
4202 <anchor id="filter-demoronizer">
4204 <screen>+filter{demoronizer} # Fix MS's non-standard use of standard charsets.</screen>
4206 <anchor id="filter-shockwave-flash">
4208 <screen>+filter{shockwave-flash} # Kill embedded Shockwave Flash objects.</screen>
4210 <anchor id="filter-quicktime-kioskmode">
4212 <screen>+filter{quicktime-kioskmode} # Make Quicktime movies saveable.</screen>
4214 <anchor id="filter-fun">
4216 <screen>+filter{fun} # Text replacements for subversive browsing fun!</screen>
4218 <anchor id="filter-crude-parental">
4220 <screen>+filter{crude-parental} # Crude parental filtering. Note that this filter doesn't work reliably.</screen>
4222 <anchor id="filter-ie-exploits">
4224 <screen>+filter{ie-exploits} # Disable some known Internet Explorer bug exploits.</screen>
4226 <anchor id="filter-site-specifics">
4228 <screen>+filter{site-specifics} # Cure for site-specific problems. Don't apply generally!</screen>
4230 <anchor id="filter-no-ping">
4232 <screen>+filter{no-ping} # Removes non-standard ping attributes in <a> and <area> tags.</screen>
4234 <anchor id="filter-google">
4236 <screen>+filter{google} # CSS-based block for Google text ads. Also removes a width limitation and the toolbar advertisement.</screen>
4238 <anchor id="filter-yahoo">
4240 <screen>+filter{yahoo} # CSS-based block for Yahoo text ads. Also removes a width limitation.</screen>
4242 <anchor id="filter-msn">
4244 <screen>+filter{msn} # CSS-based block for MSN text ads. Also removes tracking URLs and a width limitation.</screen>
4246 <anchor id="filter-blogspot">
4248 <screen>+filter{blogspot} # Cleans up some Blogspot blogs. Read the fine print before using this.</screen>
4255 <!-- ~~~~~ New section ~~~~~ -->
4256 <sect3 renderas="sect4" id="force-text-mode">
4257 <title>force-text-mode</title>
4263 <term>Typical use:</term>
4265 <para>Force <application>Privoxy</application> to treat a document as if it was in some kind of <emphasis>text</emphasis> format. </para>
4270 <term>Effect:</term>
4273 Declares a document as text, even if the <quote>Content-Type:</quote> isn't detected as such.
4280 <!-- Boolean, Parameterized, Multi-value -->
4282 <para>Boolean.</para>
4287 <term>Parameter:</term>
4299 As explained <literal><link linkend="filter">above</link></literal>,
4300 <application>Privoxy</application> tries to only filter files that are
4301 in some kind of text format. The same restrictions apply to
4302 <literal><link linkend="content-type-overwrite">content-type-overwrite</link></literal>.
4303 <literal>force-text-mode</literal> declares a document as text,
4304 without looking at the <quote>Content-Type:</quote> first.
4308 Think twice before activating this action. Filtering binary data
4309 with regular expressions can cause file damage.
4316 <term>Example usage:</term>
4327 <!-- ~~~~~ New section ~~~~~ -->
4328 <sect3 renderas="sect4" id="forward-override">
4329 <title>forward-override</title>
4335 <term>Typical use:</term>
4337 <para>Change the forwarding settings based on User-Agent or request origin</para>
4342 <term>Effect:</term>
4345 Overrules the forward directives in the configuration file.
4352 <!-- Boolean, Parameterized, Multi-value -->
4354 <para>Parameterized.</para>
4359 <term>Parameter:</term>
4363 <para><quote>forward .</quote> to use a direct connection without any additional proxies.</para>
4367 <quote>forward 127.0.0.1:8123</quote> to use the HTTP proxy listening at 127.0.0.1 port 8123.
4372 <quote>forward-socks4a 127.0.0.1:9050 .</quote> to use the socks4a proxy listening at
4373 127.0.0.1 port 9050. Replace <quote>forward-socks4a</quote> with <quote>forward-socks4</quote>
4374 to use a socks4 connection (with local DNS resolution) instead, use <quote>forward-socks5</quote>
4375 for socks5 connections (with remote DNS resolution).
4380 <quote>forward-socks4a 127.0.0.1:9050 proxy.example.org:8000</quote> to use the socks4a proxy
4381 listening at 127.0.0.1 port 9050 to reach the HTTP proxy listening at proxy.example.org port 8000.
4382 Replace <quote>forward-socks4a</quote> with <quote>forward-socks4</quote> to use a socks4 connection
4383 (with local DNS resolution) instead, use <quote>forward-socks5</quote>
4384 for socks5 connections (with remote DNS resolution).
4389 <quote>forward-webserver 127.0.0.1:80</quote> to use the HTTP
4390 server listening at 127.0.0.1 port 80 without adjusting the
4394 This makes it more convenient to use Privoxy to make
4395 existing websites available as onion services as well.
4398 Many websites serve content with hardcoded URLs and
4399 can't be easily adjusted to change the domain based
4400 on the one used by the client.
4403 Putting Privoxy between Tor and the webserver (or an stunnel
4404 that forwards to the webserver) allows to rewrite headers and
4405 content to make client and server happy at the same time.
4408 Using Privoxy for webservers that are only reachable through
4409 onion addresses and whose location is supposed to be secret
4410 is not recommended and should not be necessary anyway.
4421 This action takes parameters similar to the
4422 <link linkend="forwarding">forward</link> directives in the configuration
4423 file, but without the URL pattern. It can be used as replacement, but normally it's only
4424 used in cases where matching based on the request URL isn't sufficient.
4428 Please read the description for the <link linkend="forwarding">forward</link> directives before
4429 using this action. Forwarding to the wrong people will reduce your privacy and increase the
4430 chances of man-in-the-middle attacks.
4433 If the ports are missing or invalid, default values will be used. This might change
4434 in the future and you shouldn't rely on it. Otherwise incorrect syntax causes Privoxy
4435 to exit. Due to design limitations, invalid parameter syntax isn't detected until the
4436 action is used the first time.
4439 Use the <ulink url="http://config.privoxy.org/show-url-info">show-url-info CGI page</ulink>
4440 to verify that your forward settings do what you thought the do.
4447 <term>Example usage:</term>
4450 # Use an ssh tunnel for requests previously tagged as
4451 # <quote>User-Agent: fetch libfetch/2.0</quote> and make sure
4452 # resuming downloads continues to work.
4454 # This way you can continue to use Tor for your normal browsing,
4455 # without overloading the Tor network with your FreeBSD ports updates
4456 # or downloads of bigger files like ISOs.
4458 # Note that HTTP headers are easy to fake and therefore their
4459 # values are as (un)trustworthy as your clients and users.
4460 {+forward-override{forward-socks5 10.0.0.2:2222 .} \
4461 -hide-if-modified-since \
4462 -overwrite-last-modified \
4464 TAG:^User-Agent: fetch libfetch/2\.0$
4472 <!-- ~~~~~ New section ~~~~~ -->
4473 <sect3 renderas="sect4" id="handle-as-empty-document">
4474 <title>handle-as-empty-document</title>
4480 <term>Typical use:</term>
4482 <para>Mark URLs that should be replaced by empty documents <emphasis>if they get blocked</emphasis></para>
4487 <term>Effect:</term>
4490 This action alone doesn't do anything noticeable. It just marks URLs.
4491 If the <literal><link linkend="block">block</link></literal> action <emphasis>also applies</emphasis>,
4492 the presence or absence of this mark decides whether an HTML <quote>BLOCKED</quote>
4493 page, or an empty document will be sent to the client as a substitute for the blocked content.
4494 The <emphasis>empty</emphasis> document isn't literally empty, but actually contains a single space.
4501 <!-- Boolean, Parameterized, Multi-value -->
4503 <para>Boolean.</para>
4508 <term>Parameter:</term>
4520 Some browsers complain about syntax errors if JavaScript documents
4521 are blocked with <application>Privoxy's</application>
4522 default HTML page; this option can be used to silence them.
4523 And of course this action can also be used to eliminate the &my-app;
4524 BLOCKED message in frames.
4527 The content type for the empty document can be specified with
4528 <literal><link linkend="content-type-overwrite">content-type-overwrite{}</link></literal>,
4529 but usually this isn't necessary.
4535 <term>Example usage:</term>
4537 <screen># Block all documents on example.org that end with ".js",
4538 # but send an empty document instead of the usual HTML message.
4539 {+block{Blocked JavaScript} +handle-as-empty-document}
4548 <!-- ~~~~~ New section ~~~~~ -->
4549 <sect3 renderas="sect4" id="handle-as-image">
4550 <title>handle-as-image</title>
4554 <term>Typical use:</term>
4556 <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>
4561 <term>Effect:</term>
4564 This action alone doesn't do anything noticeable. It just marks URLs as images.
4565 If the <literal><link linkend="block">block</link></literal> action <emphasis>also applies</emphasis>,
4566 the presence or absence of this mark decides whether an HTML <quote>blocked</quote>
4567 page, or a replacement image (as determined by the <literal><link
4568 linkend="set-image-blocker">set-image-blocker</link></literal> action) will be sent to the
4569 client as a substitute for the blocked content.
4576 <!-- Boolean, Parameterized, Multi-value -->
4578 <para>Boolean.</para>
4583 <term>Parameter:</term>
4595 The below generic example section is actually part of <filename>default.action</filename>.
4596 It marks all URLs with well-known image file name extensions as images and should
4600 Users will probably only want to use the handle-as-image action in conjunction with
4601 <literal><link linkend="block">block</link></literal>, to block sources of banners, whose URLs don't
4602 reflect the file type, like in the second example section.
4605 Note that you cannot treat HTML pages as images in most cases. For instance, (in-line) ad
4606 frames require an HTML page to be sent, or they won't display properly.
4607 Forcing <literal>handle-as-image</literal> in this situation will not replace the
4608 ad frame with an image, but lead to error messages.
4614 <term>Example usage (sections):</term>
4616 <screen># Generic image extensions:
4619 /.*\.(gif|jpg|jpeg|png|bmp|ico)$
4621 # These don't look like images, but they're banners and should be
4622 # blocked as images:
4624 {+block{Nasty banners.} +handle-as-image}
4625 nasty-banner-server.example.com/junk.cgi\?output=trash
4633 <!-- ~~~~~ New section ~~~~~ -->
4634 <sect3 renderas="sect4" id="hide-accept-language">
4635 <title>hide-accept-language</title>
4641 <term>Typical use:</term>
4643 <para>Pretend to use different language settings.</para>
4648 <term>Effect:</term>
4651 Deletes or replaces the <quote>Accept-Language:</quote> HTTP header in client requests.
4658 <!-- Boolean, Parameterized, Multi-value -->
4660 <para>Parameterized.</para>
4665 <term>Parameter:</term>
4668 Keyword: <quote>block</quote>, or any user defined value.
4677 Faking the browser's language settings can be useful to make a
4678 foreign User-Agent set with
4679 <literal><link linkend="hide-user-agent">hide-user-agent</link></literal>
4683 However some sites with content in different languages check the
4684 <quote>Accept-Language:</quote> to decide which one to take by default.
4685 Sometimes it isn't possible to later switch to another language without
4686 changing the <quote>Accept-Language:</quote> header first.
4689 Therefore it's a good idea to either only change the
4690 <quote>Accept-Language:</quote> header to languages you understand,
4691 or to languages that aren't wide spread.
4694 Before setting the <quote>Accept-Language:</quote> header
4695 to a rare language, you should consider that it helps to
4696 make your requests unique and thus easier to trace.
4697 If you don't plan to change this header frequently,
4698 you should stick to a common language.
4704 <term>Example usage (section):</term>
4706 <screen># Pretend to use Canadian language settings.
4707 {+hide-accept-language{en-ca} \
4708 +hide-user-agent{Mozilla/5.0 (X11; U; OpenBSD i386; en-CA; rv:1.8.0.4) Gecko/20060628 Firefox/1.5.0.4} \
4718 <!-- ~~~~~ New section ~~~~~ -->
4719 <sect3 renderas="sect4" id="hide-content-disposition">
4720 <title>hide-content-disposition</title>
4726 <term>Typical use:</term>
4728 <para>Prevent download menus for content you prefer to view inside the browser.</para>
4733 <term>Effect:</term>
4736 Deletes or replaces the <quote>Content-Disposition:</quote> HTTP header set by some servers.
4743 <!-- Boolean, Parameterized, Multi-value -->
4745 <para>Parameterized.</para>
4750 <term>Parameter:</term>
4753 Keyword: <quote>block</quote>, or any user defined value.
4762 Some servers set the <quote>Content-Disposition:</quote> HTTP header for
4763 documents they assume you want to save locally before viewing them.
4764 The <quote>Content-Disposition:</quote> header contains the file name
4765 the browser is supposed to use by default.
4768 In most browsers that understand this header, it makes it impossible to
4769 <emphasis>just view</emphasis> the document, without downloading it first,
4770 even if it's just a simple text file or an image.
4773 Removing the <quote>Content-Disposition:</quote> header helps
4774 to prevent this annoyance, but some browsers additionally check the
4775 <quote>Content-Type:</quote> header, before they decide if they can
4776 display a document without saving it first. In these cases, you have
4777 to change this header as well, before the browser stops displaying
4781 It is also possible to change the server's file name suggestion
4782 to another one, but in most cases it isn't worth the time to set
4786 This action will probably be removed in the future,
4787 use server-header filters instead.
4793 <term>Example usage:</term>
4795 <screen># Disarm the download link in Sourceforge's patch tracker
4797 +content-type-overwrite{text/plain}\
4798 +hide-content-disposition{block} }
4799 .sourceforge.net/tracker/download\.php</screen>
4806 <!-- ~~~~~ New section ~~~~~ -->
4807 <sect3 renderas="sect4" id="hide-if-modified-since">
4808 <title>hide-if-modified-since</title>
4814 <term>Typical use:</term>
4816 <para>Prevent yet another way to track the user's steps between sessions.</para>
4821 <term>Effect:</term>
4824 Deletes the <quote>If-Modified-Since:</quote> HTTP client header or modifies its value.
4831 <!-- Boolean, Parameterized, Multi-value -->
4833 <para>Parameterized.</para>
4838 <term>Parameter:</term>
4841 Keyword: <quote>block</quote>, or a user defined value that specifies a range of hours.
4850 Removing this header is useful for filter testing, where you want to force a real
4851 reload instead of getting status code <quote>304</quote>, which would cause the
4852 browser to use a cached copy of the page.
4855 Instead of removing the header, <literal>hide-if-modified-since</literal> can
4856 also add or subtract a random amount of time to/from the header's value.
4857 You specify a range of minutes where the random factor should be chosen from and
4858 <application>Privoxy</application> does the rest. A negative value means
4859 subtracting, a positive value adding.
4862 Randomizing the value of the <quote>If-Modified-Since:</quote> makes
4863 it less likely that the server can use the time as a cookie replacement,
4864 but you will run into caching problems if the random range is too high.
4867 It is a good idea to only use a small negative value and let
4868 <literal><link linkend="overwrite-last-modified">overwrite-last-modified</link></literal>
4869 handle the greater changes.
4872 It is also recommended to use this action together with
4873 <literal><link linkend="crunch-if-none-match">crunch-if-none-match</link></literal>,
4874 otherwise it's more or less pointless.
4880 <term>Example usage (section):</term>
4882 <screen># Let the browser revalidate but make tracking based on the time less likely.
4883 {+hide-if-modified-since{-60} \
4884 +overwrite-last-modified{randomize} \
4885 +crunch-if-none-match}
4893 <!-- ~~~~~ New section ~~~~~ -->
4894 <sect3 renderas="sect4" id="hide-from-header">
4895 <title>hide-from-header</title>
4899 <term>Typical use:</term>
4901 <para>Keep your (old and ill) browser from telling web servers your email address</para>
4906 <term>Effect:</term>
4909 Deletes any existing <quote>From:</quote> HTTP header, or replaces it with the
4917 <!-- Boolean, Parameterized, Multi-value -->
4919 <para>Parameterized.</para>
4924 <term>Parameter:</term>
4927 Keyword: <quote>block</quote>, or any user defined value.
4936 The keyword <quote>block</quote> will completely remove the header
4937 (not to be confused with the <literal><link linkend="block">block</link></literal>
4941 Alternately, you can specify any value you prefer to be sent to the web
4942 server. If you do, it is a matter of fairness not to use any address that
4943 is actually used by a real person.
4946 This action is rarely needed, as modern web browsers don't send
4947 <quote>From:</quote> headers anymore.
4953 <term>Example usage:</term>
4955 <screen>+hide-from-header{block}</screen>
4957 <screen>+hide-from-header{spam-me-senseless@sittingduck.example.com}</screen>
4964 <!-- ~~~~~ New section ~~~~~ -->
4965 <sect3 renderas="sect4" id="hide-referrer">
4966 <title>hide-referrer</title>
4967 <anchor id="hide-referer">
4970 <term>Typical use:</term>
4972 <para>Conceal which link you followed to get to a particular site</para>
4977 <term>Effect:</term>
4980 Deletes the <quote>Referer:</quote> (sic) HTTP header from the client request,
4981 or replaces it with a forged one.
4988 <!-- Boolean, Parameterized, Multi-value -->
4990 <para>Parameterized.</para>
4995 <term>Parameter:</term>
4999 <para><quote>conditional-block</quote> to delete the header completely if the host has changed.</para>
5002 <para><quote>conditional-forge</quote> to forge the header if the host has changed.</para>
5005 <para><quote>block</quote> to delete the header unconditionally.</para>
5008 <para><quote>forge</quote> to pretend to be coming from the homepage of the server we are talking to.</para>
5011 <para>Any other string to set a user defined referrer.</para>
5021 <literal>conditional-block</literal> is the only parameter,
5022 that isn't easily detected in the server's log file. If it blocks the
5023 referrer, the request will look like the visitor used a bookmark or
5024 typed in the address directly.
5027 Leaving the referrer unmodified for requests on the same host
5028 allows the server owner to see the visitor's <quote>click path</quote>,
5029 but in most cases she could also get that information by comparing
5030 other parts of the log file: for example the User-Agent if it isn't
5031 a very common one, or the user's IP address if it doesn't change between
5035 Always blocking the referrer, or using a custom one, can lead to
5036 failures on servers that check the referrer before they answer any
5037 requests, in an attempt to prevent their content from being
5038 embedded or linked to elsewhere.
5041 Both <literal>conditional-block</literal> and <literal>forge</literal>
5042 will work with referrer checks, as long as content and valid referring page
5043 are on the same host. Most of the time that's the case.
5046 <literal>hide-referer</literal> is an alternate spelling of
5047 <literal>hide-referrer</literal> and the two can be can be freely
5048 substituted with each other. (<quote>referrer</quote> is the
5049 correct English spelling, however the HTTP specification has a bug - it
5050 requires it to be spelled as <quote>referer</quote>.)
5056 <term>Example usage:</term>
5058 <screen>+hide-referrer{forge}</screen>
5060 <screen>+hide-referrer{http://www.yahoo.com/}</screen>
5067 <!-- ~~~~~ New section ~~~~~ -->
5068 <sect3 renderas="sect4" id="hide-user-agent">
5069 <title>hide-user-agent</title>
5073 <term>Typical use:</term>
5075 <para>Try to conceal your type of browser and client operating system</para>
5080 <term>Effect:</term>
5083 Replaces the value of the <quote>User-Agent:</quote> HTTP header
5084 in client requests with the specified value.
5091 <!-- Boolean, Parameterized, Multi-value -->
5093 <para>Parameterized.</para>
5098 <term>Parameter:</term>
5101 Any user-defined string.
5111 This can lead to problems on web sites that depend on looking at this header in
5112 order to customize their content for different browsers (which, by the
5113 way, is <emphasis>NOT</emphasis> the right thing to do: good web sites
5114 work browser-independently).
5118 Using this action in multi-user setups or wherever different types of
5119 browsers will access the same <application>Privoxy</application> is
5120 <emphasis>not recommended</emphasis>. In single-user, single-browser
5121 setups, you might use it to delete your OS version information from
5122 the headers, because it is an invitation to exploit known bugs for your
5123 OS. It is also occasionally useful to forge this in order to access
5124 sites that won't let you in otherwise (though there may be a good
5125 reason in some cases).
5128 More information on known user-agent strings can be found at
5129 <ulink url="http://www.user-agents.org/">http://www.user-agents.org/</ulink>
5131 <ulink url="http://en.wikipedia.org/wiki/User_agent">http://en.wikipedia.org/wiki/User_agent</ulink>.
5137 <term>Example usage:</term>
5139 <screen>+hide-user-agent{Netscape 6.1 (X11; I; Linux 2.4.18 i686)}</screen>
5146 <!-- ~~~~~ New section ~~~~~ -->
5147 <sect3 renderas="sect4" id="limit-connect">
5148 <title>limit-connect</title>
5152 <term>Typical use:</term>
5154 <para>Prevent abuse of <application>Privoxy</application> as a TCP proxy relay or disable SSL for untrusted sites</para>
5159 <term>Effect:</term>
5162 Specifies to which ports HTTP CONNECT requests are allowable.
5169 <!-- Boolean, Parameterized, Multi-value -->
5171 <para>Parameterized.</para>
5176 <term>Parameter:</term>
5179 A comma-separated list of ports or port ranges (the latter using dashes, with the minimum
5180 defaulting to 0 and the maximum to 65K).
5189 By default, i.e. if no <literal>limit-connect</literal> action applies,
5190 <application>Privoxy</application> allows HTTP CONNECT requests to all
5191 ports. Use <literal>limit-connect</literal> if fine-grained control
5192 is desired for some or all destinations.
5195 The CONNECT methods exists in HTTP to allow access to secure websites
5196 (<quote>https://</quote> URLs) through proxies. It works very simply:
5197 the proxy connects to the server on the specified port, and then
5198 short-circuits its connections to the client and to the remote server.
5199 This means CONNECT-enabled proxies can be used as TCP relays very easily.
5202 <application>Privoxy</application> relays HTTPS traffic without seeing
5203 the decoded content. Websites can leverage this limitation to circumvent &my-app;'s
5204 filters. By specifying an invalid port range you can disable HTTPS entirely.
5210 <term>Example usages:</term>
5212 <!-- I had trouble getting the spacing to look right in my browser -->
5213 <!-- I probably have the wrong font setup, bollocks. -->
5214 <!-- Apparently the emphasis tag uses a proportional font no matter what -->
5215 <screen>+limit-connect{443} # Port 443 is OK.
5216 +limit-connect{80,443} # Ports 80 and 443 are OK.
5217 +limit-connect{-3, 7, 20-100, 500-} # Ports less than 3, 7, 20 to 100 and above 500 are OK.
5218 +limit-connect{-} # All ports are OK
5219 +limit-connect{,} # No HTTPS/SSL traffic is allowed</screen>
5226 <!-- ~~~~~ New section ~~~~~ -->
5227 <sect3 renderas="sect4" id="limit-cookie-lifetime">
5228 <title>limit-cookie-lifetime</title>
5232 <term>Typical use:</term>
5234 <para>Limit the lifetime of HTTP cookies to a couple of minutes or hours.</para>
5239 <term>Effect:</term>
5242 Overwrites the expires field in Set-Cookie server headers if it's above the specified limit.
5249 <!-- Boolean, Parameterized, Multi-value -->
5251 <para>Parameterized.</para>
5256 <term>Parameter:</term>
5259 The lifetime limit in minutes, or 0.
5268 This action reduces the lifetime of HTTP cookies coming from the
5269 server to the specified number of minutes, starting from the time
5270 the cookie passes Privoxy.
5273 Cookies with a lifetime below the limit are not modified.
5274 The lifetime of session cookies is set to the specified limit.
5277 The effect of this action depends on the server.
5280 In case of servers which refresh their cookies with each response
5281 (or at least frequently), the lifetime limit set by this action
5283 Thus, a session associated with the cookie continues to work with
5284 this action enabled, as long as a new request is made before the
5285 last limit set is reached.
5288 However, some servers send their cookies once, with a lifetime of several
5289 years (the year 2037 is a popular choice), and do not refresh them
5290 until a certain event in the future, for example the user logging out.
5291 In this case this action may limit the absolute lifetime of the session,
5292 even if requests are made frequently.
5295 If the parameter is <quote>0</quote>, this action behaves like
5296 <literal><link linkend="session-cookies-only">session-cookies-only</link></literal>.
5302 <term>Example usages:</term>
5304 <screen>+limit-cookie-lifetime{60}</screen>
5310 <!-- ~~~~~ New section ~~~~~ -->
5311 <sect3 renderas="sect4" id="prevent-compression">
5312 <title>prevent-compression</title>
5316 <term>Typical use:</term>
5319 Ensure that servers send the content uncompressed, so it can be
5320 passed through <literal><link linkend="filter">filter</link></literal>s.
5326 <term>Effect:</term>
5329 Removes the Accept-Encoding header which can be used to ask for compressed transfer.
5336 <!-- Boolean, Parameterized, Multi-value -->
5338 <para>Boolean.</para>
5343 <term>Parameter:</term>
5355 More and more websites send their content compressed by default, which
5356 is generally a good idea and saves bandwidth. But the <literal><link
5357 linkend="filter">filter</link></literal> and
5358 <literal><link linkend="deanimate-gifs">deanimate-gifs</link></literal>
5359 actions need access to the uncompressed data.
5362 When compiled with zlib support (available since &my-app; 3.0.7), content that should be
5363 filtered is decompressed on-the-fly and you don't have to worry about this action.
5364 If you are using an older &my-app; version, or one that hasn't been compiled with zlib
5365 support, this action can be used to convince the server to send the content uncompressed.
5368 Most text-based instances compress very well, the size is seldom decreased by less than 50%,
5369 for markup-heavy instances like news feeds saving more than 90% of the original size isn't
5373 Not using compression will therefore slow down the transfer, and you should only
5374 enable this action if you really need it. As of &my-app; 3.0.7 it's disabled in all
5375 predefined action settings.
5378 Note that some (rare) ill-configured sites don't handle requests for uncompressed
5379 documents correctly. Broken PHP applications tend to send an empty document body,
5380 some IIS versions only send the beginning of the content. If you enable
5381 <literal>prevent-compression</literal> per default, you might want to add
5382 exceptions for those sites. See the example for how to do that.
5388 <term>Example usage (sections):</term>
5391 # Selectively turn off compression, and enable a filter
5393 { +filter{tiny-textforms} +prevent-compression }
5394 # Match only these sites
5399 # Or instead, we could set a universal default:
5401 { +prevent-compression }
5404 # Then maybe make exceptions for broken sites:
5406 { -prevent-compression }
5407 .compusa.com/</screen>
5415 <!-- ~~~~~ New section ~~~~~ -->
5416 <sect3 renderas="sect4" id="overwrite-last-modified">
5417 <title>overwrite-last-modified</title>
5423 <term>Typical use:</term>
5425 <para>Prevent yet another way to track the user's steps between sessions.</para>
5430 <term>Effect:</term>
5433 Deletes the <quote>Last-Modified:</quote> HTTP server header or modifies its value.
5440 <!-- Boolean, Parameterized, Multi-value -->
5442 <para>Parameterized.</para>
5447 <term>Parameter:</term>
5450 One of the keywords: <quote>block</quote>, <quote>reset-to-request-time</quote>
5451 and <quote>randomize</quote>
5460 Removing the <quote>Last-Modified:</quote> header is useful for filter
5461 testing, where you want to force a real reload instead of getting status
5462 code <quote>304</quote>, which would cause the browser to reuse the old
5463 version of the page.
5466 The <quote>randomize</quote> option overwrites the value of the
5467 <quote>Last-Modified:</quote> header with a randomly chosen time
5468 between the original value and the current time. In theory the server
5469 could send each document with a different <quote>Last-Modified:</quote>
5470 header to track visits without using cookies. <quote>Randomize</quote>
5471 makes it impossible and the browser can still revalidate cached documents.
5474 <quote>reset-to-request-time</quote> overwrites the value of the
5475 <quote>Last-Modified:</quote> header with the current time. You could use
5476 this option together with
5477 <literal><link linkend="hide-if-modified-since">hide-if-modified-since</link></literal>
5478 to further customize your random range.
5481 The preferred parameter here is <quote>randomize</quote>. It is safe
5482 to use, as long as the time settings are more or less correct.
5483 If the server sets the <quote>Last-Modified:</quote> header to the time
5484 of the request, the random range becomes zero and the value stays the same.
5485 Therefore you should later randomize it a second time with
5486 <literal><link linkend="hide-if-modified-since">hided-if-modified-since</link></literal>,
5490 It is also recommended to use this action together with
5491 <literal><link linkend="crunch-if-none-match">crunch-if-none-match</link></literal>.
5497 <term>Example usage:</term>
5499 <screen># Let the browser revalidate without being tracked across sessions
5500 { +hide-if-modified-since{-60} \
5501 +overwrite-last-modified{randomize} \
5502 +crunch-if-none-match}
5510 <!-- ~~~~~ New section ~~~~~ -->
5511 <sect3 renderas="sect4" id="redirect">
5512 <title>redirect</title>
5518 <term>Typical use:</term>
5521 Redirect requests to other sites.
5527 <term>Effect:</term>
5530 Convinces the browser that the requested document has been moved
5531 to another location and the browser should get it from there.
5538 <!-- Boolean, Parameterized, Multi-value -->
5540 <para>Parameterized</para>
5545 <term>Parameter:</term>
5548 An absolute URL or a single pcrs command.
5557 Requests to which this action applies are answered with a
5558 HTTP redirect to URLs of your choosing. The new URL is
5559 either provided as parameter, or derived by applying a
5560 single pcrs command to the original URL.
5563 The syntax for pcrs commands is documented in the
5564 <link linkend="filter-file">filter file</link> section.
5567 Requests can't be blocked and redirected at the same time,
5568 applying this action together with
5569 <literal><link linkend="block">block</link></literal>
5570 is a configuration error. Currently the request is blocked
5571 and an error message logged, the behavior may change in the
5572 future and result in Privoxy rejecting the action file.
5575 This action can be combined with
5576 <literal><link linkend="fast-redirects">fast-redirects{check-decoded-url}</link></literal>
5577 to redirect to a decoded version of a rewritten URL.
5580 Use this action carefully, make sure not to create redirection loops
5581 and be aware that using your own redirects might make it
5582 possible to fingerprint your requests.
5585 In case of problems with your redirects, or simply to watch
5586 them working, enable <link linkend="DEBUG">debug 128</link>.
5592 <term>Example usages:</term>
5594 <screen># Replace example.com's style sheet with another one
5595 { +redirect{http://localhost/css-replacements/example.com.css} }
5596 example.com/stylesheet\.css
5598 # Create a short, easy to remember nickname for a favorite site
5599 # (relies on the browser to accept and forward invalid URLs to &my-app;)
5600 { +redirect{https://www.privoxy.org/user-manual/actions-file.html} }
5603 # Always use the expanded view for Undeadly.org articles
5604 # (Note the $ at the end of the URL pattern to make sure
5605 # the request for the rewritten URL isn't redirected as well)
5606 {+redirect{s@$@&mode=expanded@}}
5607 undeadly.org/cgi\?action=article&sid=\d*$
5609 # Redirect Google search requests to MSN
5610 {+redirect{s@^http://[^/]*/search\?q=([^&]*).*@http://search.msn.com/results.aspx?q=$1@}}
5613 # Redirect MSN search requests to Yahoo
5614 {+redirect{s@^http://[^/]*/results\.aspx\?q=([^&]*).*@http://search.yahoo.com/search?p=$1@}}
5615 search.msn.com//results\.aspx\?q=
5617 # Redirect http://example.com/&bla=fasel&toChange=foo (and any other value but "bar")
5618 # to http://example.com/&bla=fasel&toChange=bar
5620 # The URL pattern makes sure that the following request isn't redirected again.
5621 {+redirect{s@toChange=[^&]+@toChange=bar@}}
5622 example.com/.*toChange=(?!bar)
5624 # Add a shortcut to look up illumos bugs
5625 {+redirect{s@^http://i([0-9]+)/.*@https://www.illumos.org/issues/$1@}}
5626 # Redirected URL = http://i4974/
5627 # Redirect Destination = https://www.illumos.org/issues/4974
5628 i[0-9][0-9][0-9][0-9]*/
5630 # Redirect remote requests for this manual
5631 # to the local version delivered by Privoxy
5632 {+redirect{s@^http://www@http://config@}}
5633 www.privoxy.org/user-manual/</screen>
5641 <!-- ~~~~~ New section ~~~~~ -->
5642 <sect3 renderas="sect4" id="server-header-filter">
5643 <title>server-header-filter</title>
5647 <term>Typical use:</term>
5650 Rewrite or remove single server headers.
5656 <term>Effect:</term>
5659 All server headers to which this action applies are filtered on-the-fly
5660 through the specified regular expression based substitutions.
5667 <!-- boolean, parameterized, Multi-value -->
5669 <para>Multi-value.</para>
5674 <term>Parameter:</term>
5677 The name of a server-header filter, as defined in one of the
5678 <link linkend="filter-file">filter files</link>.
5687 Server-header filters are applied to each header on its own, not to
5688 all at once. This makes it easier to diagnose problems, but on the downside
5689 you can't write filters that only change header x if header y's value is z.
5690 You can do that by using tags though.
5693 Server-header filters are executed after the other header actions have finished
5694 and use their output as input.
5697 Please refer to the <link linkend="filter-file">filter file chapter</link>
5698 to learn which server-header filters are available by default, and how to
5705 <term>Example usage (section):</term>
5708 {+server-header-filter{html-to-xml}}
5709 example.org/xml-instance-that-is-delivered-as-html
5711 {+server-header-filter{xml-to-html}}
5712 example.org/instance-that-is-delivered-as-xml-but-is-not
5721 <!-- ~~~~~ New section ~~~~~ -->
5722 <sect3 renderas="sect4" id="server-header-tagger">
5723 <title>server-header-tagger</title>
5727 <term>Typical use:</term>
5730 Enable or disable filters based on the Content-Type header.
5736 <term>Effect:</term>
5739 Server headers to which this action applies are filtered on-the-fly through
5740 the specified regular expression based substitutions, the result is used as
5748 <!-- boolean, parameterized, Multi-value -->
5750 <para>Multi-value.</para>
5755 <term>Parameter:</term>
5758 The name of a server-header tagger, as defined in one of the
5759 <link linkend="filter-file">filter files</link>.
5768 Server-header taggers are applied to each header on its own,
5769 and as the header isn't modified, each tagger <quote>sees</quote>
5773 Server-header taggers are executed before all other header actions
5774 that modify server headers. Their tags can be used to control
5775 all of the other server-header actions, the content filters
5776 and the crunch actions (<link linkend="redirect">redirect</link>
5777 and <link linkend="block">block</link>).
5780 Obviously crunching based on tags created by server-header taggers
5781 doesn't prevent the request from showing up in the server's log file.
5788 <term>Example usage (section):</term>
5791 # Tag every request with the content type declared by the server
5792 {+server-header-tagger{content-type}}
5795 # If the response has a tag starting with 'image/' enable an external
5796 # filter that only applies to images.
5798 # Note that the filter is not available by default, it's just a
5799 # <literal><link linkend="external-filter-syntax">silly example</link></literal>.
5800 {+external-filter{rotate-image} +force-text-mode}
5810 <!-- ~~~~~ New section ~~~~~ -->
5811 <sect3 renderas="sect4" id="session-cookies-only">
5812 <title>session-cookies-only</title>
5816 <term>Typical use:</term>
5819 Allow only temporary <quote>session</quote> cookies (for the current
5820 browser session <emphasis>only</emphasis>).
5826 <term>Effect:</term>
5829 Deletes the <quote>expires</quote> field from <quote>Set-Cookie:</quote>
5830 server headers. Most browsers will not store such cookies permanently and
5831 forget them in between sessions.
5838 <!-- Boolean, Parameterized, Multi-value -->
5840 <para>Boolean.</para>
5845 <term>Parameter:</term>
5857 This is less strict than <literal><link linkend="crunch-incoming-cookies">crunch-incoming-cookies</link></literal> /
5858 <literal><link linkend="crunch-outgoing-cookies">crunch-outgoing-cookies</link></literal> and allows you to browse
5859 websites that insist or rely on setting cookies, without compromising your privacy too badly.
5862 Most browsers will not permanently store cookies that have been processed by
5863 <literal>session-cookies-only</literal> and will forget about them between sessions.
5864 This makes profiling cookies useless, but won't break sites which require cookies so
5865 that you can log in for transactions. This is generally turned on for all
5866 sites, and is the recommended setting.
5869 It makes <emphasis>no sense at all</emphasis> to use <literal>session-cookies-only</literal>
5870 together with <literal><link linkend="crunch-incoming-cookies">crunch-incoming-cookies</link></literal> or
5871 <literal><link linkend="crunch-outgoing-cookies">crunch-outgoing-cookies</link></literal>. If you do, cookies
5872 will be plainly killed.
5875 Note that it is up to the browser how it handles such cookies without an <quote>expires</quote>
5876 field. If you use an exotic browser, you might want to try it out to be sure.
5879 This setting also has no effect on cookies that may have been stored
5880 previously by the browser before starting <application>Privoxy</application>.
5881 These would have to be removed manually.
5884 <application>Privoxy</application> also uses
5885 the <link linkend="filter-content-cookies">content-cookies filter</link>
5886 to block some types of cookies. Content cookies are not effected by
5887 <literal>session-cookies-only</literal>.
5893 <term>Example usage:</term>
5895 <screen>+session-cookies-only</screen>
5902 <!-- ~~~~~ New section ~~~~~ -->
5903 <sect3 renderas="sect4" id="set-image-blocker">
5904 <title>set-image-blocker</title>
5908 <term>Typical use:</term>
5910 <para>Choose the replacement for blocked images</para>
5915 <term>Effect:</term>
5918 This action alone doesn't do anything noticeable. If <emphasis>both</emphasis>
5919 <literal><link linkend="block">block</link></literal> <emphasis>and</emphasis> <literal><link
5920 linkend="handle-as-image">handle-as-image</link></literal> <emphasis>also</emphasis>
5921 apply, i.e. if the request is to be blocked as an image,
5922 <emphasis>then</emphasis> the parameter of this action decides what will be
5923 sent as a replacement.
5930 <!-- Boolean, Parameterized, Multi-value -->
5932 <para>Parameterized.</para>
5937 <term>Parameter:</term>
5942 <quote>pattern</quote> to send a built-in checkerboard pattern image. The image is visually
5943 decent, scales very well, and makes it obvious where banners were busted.
5948 <quote>blank</quote> to send a built-in transparent image. This makes banners disappear
5949 completely, but makes it hard to detect where <application>Privoxy</application> has blocked
5950 images on a given page and complicates troubleshooting if <application>Privoxy</application>
5951 has blocked innocent images, like navigation icons.
5956 <quote><replaceable class="parameter">target-url</replaceable></quote> to
5957 send a redirect to <replaceable class="parameter">target-url</replaceable>. You can redirect
5958 to any image anywhere, even in your local filesystem via <quote>file:///</quote> URL.
5959 (But note that not all browsers support redirecting to a local file system).
5962 A good application of redirects is to use special <application>Privoxy</application>-built-in
5963 URLs, which send the built-in images, as <replaceable class="parameter">target-url</replaceable>.
5964 This has the same visual effect as specifying <quote>blank</quote> or <quote>pattern</quote> in
5965 the first place, but enables your browser to cache the replacement image, instead of requesting
5966 it over and over again.
5977 The URLs for the built-in images are <quote>http://config.privoxy.org/send-banner?type=<replaceable
5978 class="parameter">type</replaceable></quote>, where <replaceable class="parameter">type</replaceable> is
5979 either <quote>blank</quote> or <quote>pattern</quote>.
5982 There is a third (advanced) type, called <quote>auto</quote>. It is <emphasis>NOT</emphasis> to be
5983 used in <literal>set-image-blocker</literal>, but meant for use from <link linkend="filter-file">filters</link>.
5984 Auto will select the type of image that would have applied to the referring page, had it been an image.
5990 <term>Example usage:</term>
5995 <screen>+set-image-blocker{pattern}</screen>
5997 Redirect to the BSD daemon:
5999 <screen>+set-image-blocker{http://www.freebsd.org/gifs/dae_up3.gif}</screen>
6001 Redirect to the built-in pattern for better caching:
6003 <screen>+set-image-blocker{http://config.privoxy.org/send-banner?type=pattern}</screen>
6010 <!-- ~~~~~ New section ~~~~~ -->
6011 <sect3 id="summary">
6012 <title>Summary</title>
6014 Note that many of these actions have the potential to cause a page to
6015 misbehave, possibly even not to display at all. There are many ways
6016 a site designer may choose to design his site, and what HTTP header
6017 content, and other criteria, he may depend on. There is no way to have hard
6018 and fast rules for all sites. See the <link
6019 linkend="ACTIONSANAT">Appendix</link> for a brief example on troubleshooting
6025 <!-- ~~~~~ New section ~~~~~ -->
6026 <sect2 id="aliases">
6027 <title>Aliases</title>
6029 Custom <quote>actions</quote>, known to <application>Privoxy</application>
6030 as <quote>aliases</quote>, can be defined by combining other actions.
6031 These can in turn be invoked just like the built-in actions.
6032 Currently, an alias name can contain any character except space, tab,
6034 <quote>{</quote> and <quote>}</quote>, but we <emphasis>strongly
6035 recommend</emphasis> that you only use <quote>a</quote> to <quote>z</quote>,
6036 <quote>0</quote> to <quote>9</quote>, <quote>+</quote>, and <quote>-</quote>.
6037 Alias names are not case sensitive, and are not required to start with a
6038 <quote>+</quote> or <quote>-</quote> sign, since they are merely textually
6042 Aliases can be used throughout the actions file, but they <emphasis>must be
6043 defined in a special section at the top of the file!</emphasis>
6044 And there can only be one such section per actions file. Each actions file may
6045 have its own alias section, and the aliases defined in it are only visible
6049 There are two main reasons to use aliases: One is to save typing for frequently
6050 used combinations of actions, the other one is a gain in flexibility: If you
6051 decide once how you want to handle shops by defining an alias called
6052 <quote>shop</quote>, you can later change your policy on shops in
6053 <emphasis>one</emphasis> place, and your changes will take effect everywhere
6054 in the actions file where the <quote>shop</quote> alias is used. Calling aliases
6055 by their purpose also makes your actions files more readable.
6058 Currently, there is one big drawback to using aliases, though:
6059 <application>Privoxy</application>'s built-in web-based action file
6060 editor honors aliases when reading the actions files, but it expands
6061 them before writing. So the effects of your aliases are of course preserved,
6062 but the aliases themselves are lost when you edit sections that use aliases
6067 Now let's define some aliases...
6071 # Useful custom aliases we can use later.
6073 # Note the (required!) section header line and that this section
6074 # must be at the top of the actions file!
6078 # These aliases just save typing later:
6079 # (Note that some already use other aliases!)
6081 +crunch-all-cookies = +<link linkend="CRUNCH-INCOMING-COOKIES">crunch-incoming-cookies</link> +<link linkend="CRUNCH-OUTGOING-COOKIES">crunch-outgoing-cookies</link>
6082 -crunch-all-cookies = -<link linkend="CRUNCH-INCOMING-COOKIES">crunch-incoming-cookies</link> -<link linkend="CRUNCH-OUTGOING-COOKIES">crunch-outgoing-cookies</link>
6083 +block-as-image = +block{Blocked image.} +handle-as-image
6084 allow-all-cookies = -crunch-all-cookies -<link linkend="SESSION-COOKIES-ONLY">session-cookies-only</link> -<link linkend="FILTER-CONTENT-COOKIES">filter{content-cookies}</link>
6086 # These aliases define combinations of actions
6087 # that are useful for certain types of sites:
6089 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>
6091 shop = -crunch-all-cookies -<link linkend="FILTER-ALL-POPUPS">filter{all-popups}</link>
6093 # Short names for other aliases, for really lazy people ;-)
6095 c0 = +crunch-all-cookies
6096 c1 = -crunch-all-cookies</screen>
6099 ...and put them to use. These sections would appear in the lower part of an
6100 actions file and define exceptions to the default actions (as specified further
6101 up for the <quote>/</quote> pattern):
6105 # These sites are either very complex or very keen on
6106 # user data and require minimal interference to work:
6109 .office.microsoft.com
6110 .windowsupdate.microsoft.com
6111 # Gmail is really mail.google.com, not gmail.com
6115 # Allow cookies (for setting and retrieving your customer data)
6119 .worldpay.com # for quietpc.com
6122 # These shops require pop-ups:
6124 {-filter{all-popups} -filter{unsolicited-popups}}
6126 .overclockers.co.uk</screen>
6129 Aliases like <quote>shop</quote> and <quote>fragile</quote> are typically used for
6130 <quote>problem</quote> sites that require more than one action to be disabled
6131 in order to function properly.
6137 <!-- ~~~~~ New section ~~~~~ -->
6138 <sect2 id="act-examples">
6139 <title>Actions Files Tutorial</title>
6141 The above chapters have shown <link linkend="actions-file">which actions files
6142 there are and how they are organized</link>, how actions are <link
6143 linkend="actions">specified</link> and <link linkend="actions-apply">applied
6144 to URLs</link>, how <link linkend="af-patterns">patterns</link> work, and how to
6145 define and use <link linkend="aliases">aliases</link>. Now, let's look at an
6146 example <filename>match-all.action</filename>, <filename>default.action</filename>
6147 and <filename>user.action</filename> file and see how all these pieces come together:
6150 <sect3 id="match-all">
6151 <title>match-all.action</title>
6153 Remember <emphasis>all actions are disabled when matching starts</emphasis>,
6154 so we have to explicitly enable the ones we want.
6158 While the <filename>match-all.action</filename> file only contains a
6159 single section, it is probably the most important one. It has only one
6160 pattern, <quote><literal>/</literal></quote>, but this pattern
6161 <link linkend="af-patterns">matches all URLs</link>. Therefore, the set of
6162 actions used in this <quote>default</quote> section <emphasis>will
6163 be applied to all requests as a start</emphasis>. It can be partly or
6164 wholly overridden by other actions files like <filename>default.action</filename>
6165 and <filename>user.action</filename>, but it will still be largely responsible
6166 for your overall browsing experience.
6170 Again, at the start of matching, all actions are disabled, so there is
6171 no need to disable any actions here. (Remember: a <quote>+</quote>
6172 preceding the action name enables the action, a <quote>-</quote> disables!).
6173 Also note how this long line has been made more readable by splitting it into
6174 multiple lines with line continuation.
6179 +<link linkend="CHANGE-X-FORWARDED-FOR">change-x-forwarded-for{block}</link> \
6180 +<link linkend="HIDE-FROM-HEADER">hide-from-header{block}</link> \
6181 +<link linkend="SET-IMAGE-BLOCKER">set-image-blocker{pattern}</link> \
6187 The default behavior is now set.
6191 <sect3 id="default-action">
6192 <title>default.action</title>
6195 If you aren't a developer, there's no need for you to edit the
6196 <filename>default.action</filename> file. It is maintained by
6197 the &my-app; developers and if you disagree with some of the
6198 sections, you should overrule them in your <filename>user.action</filename>.
6202 Understanding the <filename>default.action</filename> file can
6203 help you with your <filename>user.action</filename>, though.
6207 The first section in this file is a special section for internal use
6208 that prevents older &my-app; versions from reading the file:
6212 ##########################################################################
6213 # Settings -- Don't change! For internal Privoxy use ONLY.
6214 ##########################################################################
6216 for-privoxy-version=3.0.11</screen>
6219 After that comes the (optional) alias section. We'll use the example
6220 section from the above <link linkend="aliases">chapter on aliases</link>,
6221 that also explains why and how aliases are used:
6225 ##########################################################################
6227 ##########################################################################
6230 # These aliases just save typing later:
6231 # (Note that some already use other aliases!)
6233 +crunch-all-cookies = +<link linkend="CRUNCH-INCOMING-COOKIES">crunch-incoming-cookies</link> +<link linkend="CRUNCH-OUTGOING-COOKIES">crunch-outgoing-cookies</link>
6234 -crunch-all-cookies = -<link linkend="CRUNCH-INCOMING-COOKIES">crunch-incoming-cookies</link> -<link linkend="CRUNCH-OUTGOING-COOKIES">crunch-outgoing-cookies</link>
6235 +block-as-image = +block{Blocked image.} +handle-as-image
6236 mercy-for-cookies = -crunch-all-cookies -<link linkend="SESSION-COOKIES-ONLY">session-cookies-only</link> -<link linkend="FILTER-CONTENT-COOKIES">filter{content-cookies}</link>
6238 # These aliases define combinations of actions
6239 # that are useful for certain types of sites:
6241 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>
6242 shop = -crunch-all-cookies -<link linkend="FILTER-ALL-POPUPS">filter{all-popups}</link></screen>
6245 The first of our specialized sections is concerned with <quote>fragile</quote>
6246 sites, i.e. sites that require minimum interference, because they are either
6247 very complex or very keen on tracking you (and have mechanisms in place that
6248 make them unusable for people who avoid being tracked). We will use
6249 our pre-defined <literal>fragile</literal> alias instead of stating the list
6250 of actions explicitly:
6254 ##########################################################################
6255 # Exceptions for sites that'll break under the default action set:
6256 ##########################################################################
6258 # "Fragile" Use a minimum set of actions for these sites (see alias above):
6261 .office.microsoft.com # surprise, surprise!
6262 .windowsupdate.microsoft.com
6263 mail.google.com</screen>
6266 Shopping sites are not as fragile, but they typically
6267 require cookies to log in, and pop-up windows for shopping
6268 carts or item details. Again, we'll use a pre-defined alias:
6276 .worldpay.com # for quietpc.com
6278 .scan.co.uk</screen>
6281 The <literal><link linkend="FAST-REDIRECTS">fast-redirects</link></literal>
6282 action, which may have been enabled in <filename>match-all.action</filename>,
6283 breaks some sites. So disable it for popular sites where we know it misbehaves:
6287 { -<link linkend="FAST-REDIRECTS">fast-redirects</link> }
6291 .altavista.com/.*(like|url|link):http
6292 .altavista.com/trans.*urltext=http
6293 .nytimes.com</screen>
6296 It is important that <application>Privoxy</application> knows which
6297 URLs belong to images, so that <emphasis>if</emphasis> they are to
6298 be blocked, a substitute image can be sent, rather than an HTML page.
6299 Contacting the remote site to find out is not an option, since it
6300 would destroy the loading time advantage of banner blocking, and it
6301 would feed the advertisers information about you. We can mark any
6302 URL as an image with the <literal><link
6303 linkend="handle-as-image">handle-as-image</link></literal> action,
6304 and marking all URLs that end in a known image file extension is a
6309 ##########################################################################
6311 ##########################################################################
6313 # Define which file types will be treated as images, in case they get
6314 # blocked further down this file:
6316 { +<link linkend="HANDLE-AS-IMAGE">handle-as-image</link> }
6317 /.*\.(gif|jpe?g|png|bmp|ico)$</screen>
6320 And then there are known banner sources. They often use scripts to
6321 generate the banners, so it won't be visible from the URL that the
6322 request is for an image. Hence we block them <emphasis>and</emphasis>
6323 mark them as images in one go, with the help of our
6324 <literal>+block-as-image</literal> alias defined above. (We could of
6325 course just as well use <literal>+<link linkend="block">block</link>
6326 +<link linkend="handle-as-image">handle-as-image</link></literal> here.)
6327 Remember that the type of the replacement image is chosen by the
6328 <literal><link linkend="set-image-blocker">set-image-blocker</link></literal>
6329 action. Since all URLs have matched the default section with its
6330 <literal>+<link linkend="set-image-blocker">set-image-blocker</link>{pattern}</literal>
6331 action before, it still applies and needn't be repeated:
6335 # Known ad generators:
6340 .ad.*.doubleclick.net
6341 .a.yimg.com/(?:(?!/i/).)*$
6342 .a[0-9].yimg.com/(?:(?!/i/).)*$
6347 One of the most important jobs of <application>Privoxy</application>
6348 is to block banners. Many of these can be <quote>blocked</quote>
6349 by the <literal><link linkend="filter">filter</link>{banners-by-size}</literal>
6350 action, which we enabled above, and which deletes the references to banner
6351 images from the pages while they are loaded, so the browser doesn't request
6352 them anymore, and hence they don't need to be blocked here. But this naturally
6353 doesn't catch all banners, and some people choose not to use filters, so we
6354 need a comprehensive list of patterns for banner URLs here, and apply the
6355 <literal><link linkend="block">block</link></literal> action to them.
6358 First comes many generic patterns, which do most of the work, by
6359 matching typical domain and path name components of banners. Then comes
6360 a list of individual patterns for specific sites, which is omitted here
6361 to keep the example short:
6365 ##########################################################################
6366 # Block these fine banners:
6367 ##########################################################################
6368 { <link linkend="BLOCK">+block{Banner ads.}</link> }
6376 /.*count(er)?\.(pl|cgi|exe|dll|asp|php[34]?)
6377 /(?:.*/)?(publicite|werbung|rekla(ma|me|am)|annonse|maino(kset|nta|s)?)/
6379 # Site-specific patterns (abbreviated):
6381 .hitbox.com</screen>
6384 It's quite remarkable how many advertisers actually call their banner
6385 servers ads.<replaceable>company</replaceable>.com, or call the directory
6386 in which the banners are stored literally <quote>banners</quote>. So the above
6387 generic patterns are surprisingly effective.
6390 But being very generic, they necessarily also catch URLs that we don't want
6391 to block. The pattern <literal>.*ads.</literal> e.g. catches
6392 <quote>nasty-<emphasis>ads</emphasis>.nasty-corp.com</quote> as intended,
6393 but also <quote>downlo<emphasis>ads</emphasis>.sourcefroge.net</quote> or
6394 <quote><emphasis>ads</emphasis>l.some-provider.net.</quote> So here come some
6395 well-known exceptions to the <literal>+<link linkend="BLOCK">block</link></literal>
6399 Note that these are exceptions to exceptions from the default! Consider the URL
6400 <quote>downloads.sourcefroge.net</quote>: Initially, all actions are deactivated,
6401 so it wouldn't get blocked. Then comes the defaults section, which matches the
6402 URL, but just deactivates the <literal><link linkend="BLOCK">block</link></literal>
6403 action once again. Then it matches <literal>.*ads.</literal>, an exception to the
6404 general non-blocking policy, and suddenly
6405 <literal><link linkend="BLOCK">+block</link></literal> applies. And now, it'll match
6406 <literal>.*loads.</literal>, where <literal><link linkend="BLOCK">-block</link></literal>
6407 applies, so (unless it matches <emphasis>again</emphasis> further down) it ends up
6408 with no <literal><link linkend="BLOCK">block</link></literal> action applying.
6412 ##########################################################################
6413 # Save some innocent victims of the above generic block patterns:
6414 ##########################################################################
6418 { -<link linkend="BLOCK">block</link> }
6419 adv[io]*. # (for advogato.org and advice.*)
6420 adsl. # (has nothing to do with ads)
6421 adobe. # (has nothing to do with ads either)
6422 ad[ud]*. # (adult.* and add.*)
6423 .edu # (universities don't host banners (yet!))
6424 .*loads. # (downloads, uploads etc)
6432 www.globalintersec.com/adv # (adv = advanced)
6433 www.ugu.com/sui/ugu/adv</screen>
6436 Filtering source code can have nasty side effects,
6437 so make an exception for our friends at sourceforge.net,
6438 and all paths with <quote>cvs</quote> in them. Note that
6439 <literal>-<link linkend="FILTER">filter</link></literal>
6440 disables <emphasis>all</emphasis> filters in one fell swoop!
6444 # Don't filter code!
6446 { -<link linkend="FILTER">filter</link> }
6451 .sourceforge.net</screen>
6454 The actual <filename>default.action</filename> is of course much more
6455 comprehensive, but we hope this example made clear how it works.
6460 <sect3 id="user-action"><title>user.action</title>
6463 So far we are painting with a broad brush by setting general policies,
6464 which would be a reasonable starting point for many people. Now,
6465 you might want to be more specific and have customized rules that
6466 are more suitable to your personal habits and preferences. These would
6467 be for narrowly defined situations like your ISP or your bank, and should
6468 be placed in <filename>user.action</filename>, which is parsed after all other
6469 actions files and hence has the last word, over-riding any previously
6470 defined actions. <filename>user.action</filename> is also a
6471 <emphasis>safe</emphasis> place for your personal settings, since
6472 <filename>default.action</filename> is actively maintained by the
6473 <application>Privoxy</application> developers and you'll probably want
6474 to install updated versions from time to time.
6478 So let's look at a few examples of things that one might typically do in
6479 <filename>user.action</filename>:
6483 <!-- brief sample user.action here -->
6486 # My user.action file. <fred@example.com></screen>
6489 As <link linkend="aliases">aliases</link> are local to the actions
6490 file that they are defined in, you can't use the ones from
6491 <filename>default.action</filename>, unless you repeat them here:
6495 # Aliases are local to the file they are defined in.
6496 # (Re-)define aliases for this file:
6500 # These aliases just save typing later, and the alias names should
6501 # be self explanatory.
6503 +crunch-all-cookies = +crunch-incoming-cookies +crunch-outgoing-cookies
6504 -crunch-all-cookies = -crunch-incoming-cookies -crunch-outgoing-cookies
6505 allow-all-cookies = -crunch-all-cookies -session-cookies-only
6506 allow-popups = -filter{all-popups}
6507 +block-as-image = +block{Blocked as image.} +handle-as-image
6508 -block-as-image = -block
6510 # These aliases define combinations of actions that are useful for
6511 # certain types of sites:
6513 fragile = -block -crunch-all-cookies -filter -fast-redirects -hide-referrer
6514 shop = -crunch-all-cookies allow-popups
6516 # Allow ads for selected useful free sites:
6518 allow-ads = -block -filter{banners-by-size} -filter{banners-by-link}
6520 # Alias for specific file types that are text, but might have conflicting
6521 # MIME types. We want the browser to force these to be text documents.
6522 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>
6525 Say you have accounts on some sites that you visit regularly, and
6526 you don't want to have to log in manually each time. So you'd like
6527 to allow persistent cookies for these sites. The
6528 <literal>allow-all-cookies</literal> alias defined above does exactly
6529 that, i.e. it disables crunching of cookies in any direction, and the
6530 processing of cookies to make them only temporary.
6534 { allow-all-cookies }
6538 .redhat.com</screen>
6541 Your bank is allergic to some filter, but you don't know which, so you disable them all:
6545 { -<link linkend="FILTER">filter</link> }
6546 .your-home-banking-site.com</screen>
6549 Some file types you may not want to filter for various reasons:
6553 # Technical documentation is likely to contain strings that might
6554 # erroneously get altered by the JavaScript-oriented filters:
6559 # And this stupid host sends streaming video with a wrong MIME type,
6560 # so that Privoxy thinks it is getting HTML and starts filtering:
6562 stupid-server.example.com/</screen>
6565 Example of a simple <link linkend="BLOCK">block</link> action. Say you've
6566 seen an ad on your favourite page on example.com that you want to get rid of.
6567 You have right-clicked the image, selected <quote>copy image location</quote>
6568 and pasted the URL below while removing the leading http://, into a
6569 <literal>{ +block{} }</literal> section. Note that <literal>{ +handle-as-image
6570 }</literal> need not be specified, since all URLs ending in
6571 <literal>.gif</literal> will be tagged as images by the general rules as set
6572 in default.action anyway:
6576 { +<link linkend="BLOCK">block</link>{Nasty ads.} }
6577 www.example.com/nasty-ads/sponsor\.gif
6578 another.example.net/more/junk/here/</screen>
6581 The URLs of dynamically generated banners, especially from large banner
6582 farms, often don't use the well-known image file name extensions, which
6583 makes it impossible for <application>Privoxy</application> to guess
6584 the file type just by looking at the URL.
6585 You can use the <literal>+block-as-image</literal> alias defined above for
6587 Note that objects which match this rule but then turn out NOT to be an
6588 image are typically rendered as a <quote>broken image</quote> icon by the
6589 browser. Use cautiously.
6597 ar.atwola.com/</screen>
6600 Now you noticed that the default configuration breaks Forbes Magazine,
6601 but you were too lazy to find out which action is the culprit, and you
6602 were again too lazy to give <link linkend="contact">feedback</link>, so
6603 you just used the <literal>fragile</literal> alias on the site, and
6604 -- <emphasis>whoa!</emphasis> -- it worked. The <literal>fragile</literal>
6605 aliases disables those actions that are most likely to break a site. Also,
6606 good for testing purposes to see if it is <application>Privoxy</application>
6607 that is causing the problem or not. We later find other regular sites
6608 that misbehave, and add those to our personalized list of troublemakers:
6615 .mybank.com</screen>
6618 You like the <quote>fun</quote> text replacements in <filename>default.filter</filename>,
6619 but it is disabled in the distributed actions file.
6620 So you'd like to turn it on in your private,
6621 update-safe config, once and for all:
6625 { +<link linkend="filter-fun">filter{fun}</link> }
6626 / # For ALL sites!</screen>
6629 Note that the above is not really a good idea: There are exceptions
6630 to the filters in <filename>default.action</filename> for things that
6631 really shouldn't be filtered, like code on CVS->Web interfaces. Since
6632 <filename>user.action</filename> has the last word, these exceptions
6633 won't be valid for the <quote>fun</quote> filtering specified here.
6637 You might also worry about how your favourite free websites are
6638 funded, and find that they rely on displaying banner advertisements
6639 to survive. So you might want to specifically allow banners for those
6640 sites that you feel provide value to you:
6650 Note that <literal>allow-ads</literal> has been aliased to
6651 <literal>-<link linkend="block">block</link></literal>,
6652 <literal>-<link linkend="filter-banners-by-size">filter{banners-by-size}</link></literal>, and
6653 <literal>-<link linkend="filter-banners-by-link">filter{banners-by-link}</link></literal> above.
6657 Invoke another alias here to force an over-ride of the MIME type <literal>
6658 application/x-sh</literal> which typically would open a download type
6659 dialog. In my case, I want to look at the shell script, and then I can save
6660 it should I choose to.
6668 <filename>user.action</filename> is generally the best place to define
6669 exceptions and additions to the default policies of
6670 <filename>default.action</filename>. Some actions are safe to have their
6671 default policies set here though. So let's set a default policy to have a
6672 <quote>blank</quote> image as opposed to the checkerboard pattern for
6673 <emphasis>ALL</emphasis> sites. <quote>/</quote> of course matches all URL
6678 { +<link linkend="set-image-blocker">set-image-blocker{blank}</link> }
6679 / # ALL sites</screen>
6684 <!-- ~ End section ~ -->
6688 <!-- ~ End section ~ -->
6690 <!-- ~~~~~~~~ New section Header ~~~~~~~~~ -->
6692 <sect1 id="filter-file">
6693 <title>Filter Files</title>
6696 On-the-fly text substitutions need
6697 to be defined in a <quote>filter file</quote>. Once defined, they
6698 can then be invoked as an <quote>action</quote>.
6702 &my-app; supports three different pcrs-based filter actions:
6703 <literal><link linkend="filter">filter</link></literal> to
6704 rewrite the content that is send to the client,
6705 <literal><link linkend="client-header-filter">client-header-filter</link></literal>
6706 to rewrite headers that are send by the client, and
6707 <literal><link linkend="server-header-filter">server-header-filter</link></literal>
6708 to rewrite headers that are send by the server.
6712 &my-app; also supports two tagger actions:
6713 <literal><link linkend="client-header-tagger">client-header-tagger</link></literal>
6715 <literal><link linkend="server-header-tagger">server-header-tagger</link></literal>.
6716 Taggers and filters use the same syntax in the filter files, the difference
6717 is that taggers don't modify the text they are filtering, but use a rewritten
6718 version of the filtered text as tag. The tags can then be used to change the
6719 applying actions through sections with <link linkend="tag-pattern">tag-patterns</link>.
6723 Finally &my-app; supports the
6724 <literal><link linkend="external-filter">external-filter</link></literal> action
6725 to enable <literal><link linkend="external-filter-syntax">external filters</link></literal>
6726 written in proper programming languages.
6731 Multiple filter files can be defined through the <literal> <link
6732 linkend="filterfile">filterfile</link></literal> config directive. The filters
6733 as supplied by the developers are located in
6734 <filename>default.filter</filename>. It is recommended that any locally
6735 defined or modified filters go in a separately defined file such as
6736 <filename>user.filter</filename>.
6740 Common tasks for content filters are to eliminate common annoyances in
6741 HTML and JavaScript, such as pop-up windows,
6742 exit consoles, crippled windows without navigation tools, the
6743 infamous <BLINK> tag etc, to suppress images with certain
6744 width and height attributes (standard banner sizes or web-bugs),
6745 or just to have fun.
6749 Enabled content filters are applied to any content whose
6750 <quote>Content Type</quote> header is recognised as a sign
6751 of text-based content, with the exception of <literal>text/plain</literal>.
6752 Use the <link linkend="FORCE-TEXT-MODE">force-text-mode</link> action
6753 to also filter other content.
6757 Substitutions are made at the source level, so if you want to <quote>roll
6758 your own</quote> filters, you should first be familiar with HTML syntax,
6759 and, of course, regular expressions.
6763 Just like the <link linkend="actions-file">actions files</link>, the
6764 filter file is organized in sections, which are called <emphasis>filters</emphasis>
6765 here. Each filter consists of a heading line, that starts with one of the
6766 <emphasis>keywords</emphasis> <literal>FILTER:</literal>,
6767 <literal>CLIENT-HEADER-FILTER:</literal> or <literal>SERVER-HEADER-FILTER:</literal>
6768 followed by the filter's <emphasis>name</emphasis>, and a short (one line)
6769 <emphasis>description</emphasis> of what it does. Below that line
6770 come the <emphasis>jobs</emphasis>, i.e. lines that define the actual
6771 text substitutions. By convention, the name of a filter
6772 should describe what the filter <emphasis>eliminates</emphasis>. The
6773 comment is used in the <ulink url="http://config.privoxy.org/">web-based
6774 user interface</ulink>.
6778 Once a filter called <replaceable>name</replaceable> has been defined
6779 in the filter file, it can be invoked by using an action of the form
6780 +<literal><link linkend="filter">filter</link>{<replaceable>name</replaceable>}</literal>
6781 in any <link linkend="actions-file">actions file</link>.
6785 Filter definitions start with a header line that contains the filter
6786 type, the filter name and the filter description.
6787 A content filter header line for a filter called <quote>foo</quote> could look
6791 <screen>FILTER: foo Replace all "foo" with "bar"</screen>
6794 Below that line, and up to the next header line, come the jobs that
6795 define what text replacements the filter executes. They are specified
6796 in a syntax that imitates <ulink url="http://www.perl.org/">Perl</ulink>'s
6797 <literal>s///</literal> operator. If you are familiar with Perl, you
6798 will find this to be quite intuitive, and may want to look at the
6799 PCRS documentation for the subtle differences to Perl behaviour.
6803 Most notably, the non-standard option letter <literal>U</literal> is supported,
6804 which turns the default to ungreedy matching (add <literal>?</literal> to
6805 quantifiers to turn them greedy again).
6809 The non-standard option letter <literal>D</literal> (dynamic) allows
6810 to use the variables $host, $origin (the IP address the request came from),
6811 $path, $url and $listen-address (the address on which Privoxy accepted the
6812 client request. Example: 127.0.0.1:8118).
6813 They will be replaced with the value they refer to before the filter
6818 Note that '$' is a bad choice for a delimiter in a dynamic filter as you
6819 might end up with unintended variables if you use a variable name
6820 directly after the delimiter. Variables will be resolved without
6821 escaping anything, therefore you also have to be careful not to chose
6822 delimiters that appear in the replacement text. For example '<' should
6823 be save, while '?' will sooner or later cause conflicts with $url.
6827 The non-standard option letter <literal>T</literal> (trivial) prevents
6828 parsing for backreferences in the substitute. Use it if you want to include
6829 text like '$&' in your substitute without quoting.
6834 <ulink url="http://en.wikipedia.org/wiki/Regular_expressions"><quote>Regular
6835 Expressions</quote></ulink>, you might want to take a look at
6836 the <link linkend="regex">Appendix on regular expressions</link>, and
6837 see the <ulink url="http://perldoc.perl.org/perlre.html">Perl
6839 <ulink url="http://perldoc.perl.org/perlop.html">the
6840 <literal>s///</literal> operator's syntax</ulink> and <ulink
6841 url="http://perldoc.perl.org/perlre.html">Perl-style regular
6842 expressions</ulink> in general.
6843 The below examples might also help to get you started.
6847 <!-- ~~~~~~~~ New section Header ~~~~~~~~~ -->
6849 <sect2 id="filter-file-tut"><title>Filter File Tutorial</title>
6851 Now, let's complete our <quote>foo</quote> content filter. We have already defined
6852 the heading, but the jobs are still missing. Since all it does is to replace
6853 <quote>foo</quote> with <quote>bar</quote>, there is only one (trivial) job
6857 <screen>s/foo/bar/</screen>
6860 But wait! Didn't the comment say that <emphasis>all</emphasis> occurrences
6861 of <quote>foo</quote> should be replaced? Our current job will only take
6862 care of the first <quote>foo</quote> on each page. For global substitution,
6863 we'll need to add the <literal>g</literal> option:
6866 <screen>s/foo/bar/g</screen>
6869 Our complete filter now looks like this:
6872 <screen>FILTER: foo Replace all "foo" with "bar"
6873 s/foo/bar/g</screen>
6876 Let's look at some real filters for more interesting examples. Here you see
6877 a filter that protects against some common annoyances that arise from JavaScript
6878 abuse. Let's look at its jobs one after the other:
6883 FILTER: js-annoyances Get rid of particularly annoying JavaScript abuse
6885 # Get rid of JavaScript referrer tracking. Test page: http://www.randomoddness.com/untitled.htm
6887 s|(<script.*)document\.referrer(.*</script>)|$1"Not Your Business!"$2|Usg</screen>
6890 Following the header line and a comment, you see the job. Note that it uses
6891 <literal>|</literal> as the delimiter instead of <literal>/</literal>, because
6892 the pattern contains a forward slash, which would otherwise have to be escaped
6893 by a backslash (<literal>\</literal>).
6897 Now, let's examine the pattern: it starts with the text <literal><script.*</literal>
6898 enclosed in parentheses. Since the dot matches any character, and <literal>*</literal>
6899 means: <quote>Match an arbitrary number of the element left of myself</quote>, this
6900 matches <quote><script</quote>, followed by <emphasis>any</emphasis> text, i.e.
6901 it matches the whole page, from the start of the first <script> tag.
6905 That's more than we want, but the pattern continues: <literal>document\.referrer</literal>
6906 matches only the exact string <quote>document.referrer</quote>. The dot needed to
6907 be <emphasis>escaped</emphasis>, i.e. preceded by a backslash, to take away its
6908 special meaning as a joker, and make it just a regular dot. So far, the meaning is:
6909 Match from the start of the first <script> tag in a the page, up to, and including,
6910 the text <quote>document.referrer</quote>, if <emphasis>both</emphasis> are present
6911 in the page (and appear in that order).
6915 But there's still more pattern to go. The next element, again enclosed in parentheses,
6916 is <literal>.*</script></literal>. You already know what <literal>.*</literal>
6917 means, so the whole pattern translates to: Match from the start of the first <script>
6918 tag in a page to the end of the last <script> tag, provided that the text
6919 <quote>document.referrer</quote> appears somewhere in between.
6923 This is still not the whole story, since we have ignored the options and the parentheses:
6924 The portions of the page matched by sub-patterns that are enclosed in parentheses, will be
6925 remembered and be available through the variables <literal>$1, $2, ...</literal> in
6926 the substitute. The <literal>U</literal> option switches to ungreedy matching, which means
6927 that the first <literal>.*</literal> in the pattern will only <quote>eat up</quote> all
6928 text in between <quote><script</quote> and the <emphasis>first</emphasis> occurrence
6929 of <quote>document.referrer</quote>, and that the second <literal>.*</literal> will
6930 only span the text up to the <emphasis>first</emphasis> <quote></script></quote>
6931 tag. Furthermore, the <literal>s</literal> option says that the match may span
6932 multiple lines in the page, and the <literal>g</literal> option again means that the
6933 substitution is global.
6937 So, to summarize, the pattern means: Match all scripts that contain the text
6938 <quote>document.referrer</quote>. Remember the parts of the script from
6939 (and including) the start tag up to (and excluding) the string
6940 <quote>document.referrer</quote> as <literal>$1</literal>, and the part following
6941 that string, up to and including the closing tag, as <literal>$2</literal>.
6945 Now the pattern is deciphered, but wasn't this about substituting things? So
6946 lets look at the substitute: <literal>$1"Not Your Business!"$2</literal> is
6947 easy to read: The text remembered as <literal>$1</literal>, followed by
6948 <literal>"Not Your Business!"</literal> (<emphasis>including</emphasis>
6949 the quotation marks!), followed by the text remembered as <literal>$2</literal>.
6950 This produces an exact copy of the original string, with the middle part
6951 (the <quote>document.referrer</quote>) replaced by <literal>"Not Your
6952 Business!"</literal>.
6956 The whole job now reads: Replace <quote>document.referrer</quote> by
6957 <literal>"Not Your Business!"</literal> wherever it appears inside a
6958 <script> tag. Note that this job won't break JavaScript syntax,
6959 since both the original and the replacement are syntactically valid
6960 string objects. The script just won't have access to the referrer
6961 information anymore.
6965 We'll show you two other jobs from the JavaScript taming department, but
6966 this time only point out the constructs of special interest:
6970 # The status bar is for displaying link targets, not pointless blahblah
6972 s/window\.status\s*=\s*(['"]).*?\1/dUmMy=1/ig</screen>
6975 <literal>\s</literal> stands for whitespace characters (space, tab, newline,
6976 carriage return, form feed), so that <literal>\s*</literal> means: <quote>zero
6977 or more whitespace</quote>. The <literal>?</literal> in <literal>.*?</literal>
6978 makes this matching of arbitrary text ungreedy. (Note that the <literal>U</literal>
6979 option is not set). The <literal>['"]</literal> construct means: <quote>a single
6980 <emphasis>or</emphasis> a double quote</quote>. Finally, <literal>\1</literal> is
6981 a back-reference to the first parenthesis just like <literal>$1</literal> above,
6982 with the difference that in the <emphasis>pattern</emphasis>, a backslash indicates
6983 a back-reference, whereas in the <emphasis>substitute</emphasis>, it's the dollar.
6987 So what does this job do? It replaces assignments of single- or double-quoted
6988 strings to the <quote>window.status</quote> object with a dummy assignment
6989 (using a variable name that is hopefully odd enough not to conflict with
6990 real variables in scripts). Thus, it catches many cases where e.g. pointless
6991 descriptions are displayed in the status bar instead of the link target when
6992 you move your mouse over links.
6996 # Kill OnUnload popups. Yummy. Test: http://www.zdnet.com/zdsubs/yahoo/tree/yfs.html
6998 s/(<body [^>]*)onunload(.*>)/$1never$2/iU</screen>
7002 <ulink url="http://www.w3.org/TR/2000/REC-DOM-Level-2-Events-20001113/events.html#Events-eventgroupings-htmlevents">OnUnload
7003 event binding</ulink> in the HTML DOM was a <emphasis>CRIME</emphasis>.
7004 When I close a browser window, I want it to close and die. Basta.
7005 This job replaces the <quote>onunload</quote> attribute in
7006 <quote><body></quote> tags with the dummy word <literal>never</literal>.
7007 Note that the <literal>i</literal> option makes the pattern matching
7008 case-insensitive. Also note that ungreedy matching alone doesn't always guarantee
7009 a minimal match: In the first parenthesis, we had to use <literal>[^>]*</literal>
7010 instead of <literal>.*</literal> to prevent the match from exceeding the
7011 <body> tag if it doesn't contain <quote>OnUnload</quote>, but the page's
7016 The last example is from the fun department:
7020 FILTER: fun Fun text replacements
7022 # Spice the daily news:
7024 s/microsoft(?!\.com)/MicroSuck/ig</screen>
7027 Note the <literal>(?!\.com)</literal> part (a so-called negative lookahead)
7028 in the job's pattern, which means: Don't match, if the string
7029 <quote>.com</quote> appears directly following <quote>microsoft</quote>
7030 in the page. This prevents links to microsoft.com from being trashed, while
7031 still replacing the word everywhere else.
7035 # Buzzword Bingo (example for extended regex syntax)
7037 s* industry[ -]leading \
7039 | customer[ -]focused \
7040 | market[ -]driven \
7041 | award[ -]winning # Comments are OK, too! \
7042 | high[ -]performance \
7043 | solutions[ -]based \
7047 *<font color="red"><b>BINGO!</b></font> \
7051 The <literal>x</literal> option in this job turns on extended syntax, and allows for
7052 e.g. the liberal use of (non-interpreted!) whitespace for nicer formatting.
7060 <!-- ~~~~~~~~ New section Header ~~~~~~~~~ -->
7062 <sect2 id="predefined-filters"><title>The Pre-defined Filters</title>
7066 Note each filter is also listed in the +filter action section above. Please
7067 keep these listings in sync.
7072 The distribution <filename>default.filter</filename> file contains a selection of
7073 pre-defined filters for your convenience:
7078 <term><emphasis>js-annoyances</emphasis></term>
7081 The purpose of this filter is to get rid of particularly annoying JavaScript abuse.
7087 replaces JavaScript references to the browser's referrer information
7088 with the string "Not Your Business!". This compliments the <literal><link
7089 linkend="hide-referrer">hide-referrer</link></literal> action on the content level.
7094 removes the bindings to the DOM's
7095 <ulink url="http://www.w3.org/TR/2000/REC-DOM-Level-2-Events-20001113/events.html#Events-eventgroupings-htmlevents">unload
7096 event</ulink> which we feel has no right to exist and is responsible for most <quote>exit consoles</quote>, i.e.
7097 nasty windows that pop up when you close another one.
7102 removes code that causes new windows to be opened with undesired properties, such as being
7103 full-screen, non-resizeable, without location, status or menu bar etc.
7108 Use with caution. This is an aggressive filter, and can break sites that
7109 rely heavily on JavaScript.
7115 <term><emphasis>js-events</emphasis></term>
7118 This is a very radical measure. It removes virtually all JavaScript event bindings, which
7119 means that scripts can not react to user actions such as mouse movements or clicks, window
7120 resizing etc, anymore. Use with caution!
7123 We <emphasis>strongly discourage</emphasis> using this filter as a default since it breaks
7124 many legitimate scripts. It is meant for use only on extra-nasty sites (should you really
7131 <term><emphasis>html-annoyances</emphasis></term>
7134 This filter will undo many common instances of HTML based abuse.
7137 The <literal>BLINK</literal> and <literal>MARQUEE</literal> tags
7138 are neutralized (yeah baby!), and browser windows will be created as
7139 resizeable (as of course they should be!), and will have location,
7140 scroll and menu bars -- even if specified otherwise.
7146 <term><emphasis>content-cookies</emphasis></term>
7149 Most cookies are set in the HTTP dialog, where they can be intercepted
7151 <literal><link linkend="crunch-incoming-cookies">crunch-incoming-cookies</link></literal>
7152 and <literal><link linkend="crunch-outgoing-cookies">crunch-outgoing-cookies</link></literal>
7153 actions. But web sites increasingly make use of HTML meta tags and JavaScript
7154 to sneak cookies to the browser on the content level.
7157 This filter disables most HTML and JavaScript code that reads or sets
7158 cookies. It cannot detect all clever uses of these types of code, so it
7159 should not be relied on as an absolute fix. Use it wherever you would also
7160 use the cookie crunch actions.
7166 <term><emphasis>refresh-tags</emphasis></term>
7169 Disable any refresh tags if the interval is greater than nine seconds (so
7170 that redirections done via refresh tags are not destroyed). This is useful
7171 for dial-on-demand setups, or for those who find this HTML feature
7178 <term><emphasis>unsolicited-popups</emphasis></term>
7181 This filter attempts to prevent only <quote>unsolicited</quote> pop-up
7182 windows from opening, yet still allow pop-up windows that the user
7183 has explicitly chosen to open. It was added in version 3.0.1,
7184 as an improvement over earlier such filters.
7187 Technical note: The filter works by redefining the window.open JavaScript
7188 function to a dummy function, <literal>PrivoxyWindowOpen()</literal>,
7189 during the loading and rendering phase of each HTML page access, and
7190 restoring the function afterward.
7193 This is recommended only for browsers that cannot perform this function
7194 reliably themselves. And be aware that some sites require such windows
7195 in order to function normally. Use with caution.
7201 <term><emphasis>all-popups</emphasis></term>
7204 Attempt to prevent <emphasis>all</emphasis> pop-up windows from opening.
7205 Note this should be used with even more discretion than the above, since
7206 it is more likely to break some sites that require pop-ups for normal
7207 usage. Use with caution.
7213 <term><emphasis>img-reorder</emphasis></term>
7216 This is a helper filter that has no value if used alone. It makes the
7217 <literal>banners-by-size</literal> and <literal>banners-by-link</literal>
7218 (see below) filters more effective and should be enabled together with them.
7224 <term><emphasis>banners-by-size</emphasis></term>
7227 This filter removes image tags purely based on what size they are. Fortunately
7228 for us, many ads and banner images tend to conform to certain standardized
7229 sizes, which makes this filter quite effective for ad stripping purposes.
7232 Occasionally this filter will cause false positives on images that are not ads,
7233 but just happen to be of one of the standard banner sizes.
7236 Recommended only for those who require extreme ad blocking. The default
7237 block rules should catch 95+% of all ads <emphasis>without</emphasis> this filter enabled.
7243 <term><emphasis>banners-by-link</emphasis></term>
7246 This is an experimental filter that attempts to kill any banners if
7247 their URLs seem to point to known or suspected click trackers. It is currently
7248 not of much value and is not recommended for use by default.
7254 <term><emphasis>webbugs</emphasis></term>
7257 Webbugs are small, invisible images (technically 1X1 GIF images), that
7258 are used to track users across websites, and collect information on them.
7259 As an HTML page is loaded by the browser, an embedded image tag causes the
7260 browser to contact a third-party site, disclosing the tracking information
7261 through the requested URL and/or cookies for that third-party domain, without
7262 the user ever becoming aware of the interaction with the third-party site.
7263 HTML-ized spam also uses a similar technique to verify email addresses.
7266 This filter removes the HTML code that loads such <quote>webbugs</quote>.
7272 <term><emphasis>tiny-textforms</emphasis></term>
7275 A rather special-purpose filter that can be used to enlarge textareas (those
7276 multi-line text boxes in web forms) and turn off hard word wrap in them.
7277 It was written for the sourceforge.net tracker system where such boxes are
7278 a nuisance, but it can be handy on other sites, too.
7281 It is not recommended to use this filter as a default.
7287 <term><emphasis>jumping-windows</emphasis></term>
7290 Many consider windows that move, or resize themselves to be abusive. This filter
7291 neutralizes the related JavaScript code. Note that some sites might not display
7292 or behave as intended when using this filter. Use with caution.
7298 <term><emphasis>frameset-borders</emphasis></term>
7301 Some web designers seem to assume that everyone in the world will view their
7302 web sites using the same browser brand and version, screen resolution etc,
7303 because only that assumption could explain why they'd use static frame sizes,
7304 yet prevent their frames from being resized by the user, should they be too
7305 small to show their whole content.
7308 This filter removes the related HTML code. It should only be applied to sites
7315 <term><emphasis>demoronizer</emphasis></term>
7318 Many Microsoft products that generate HTML use non-standard extensions (read:
7319 violations) of the ISO 8859-1 aka Latin-1 character set. This can cause those
7320 HTML documents to display with errors on standard-compliant platforms.
7323 This filter translates the MS-only characters into Latin-1 equivalents.
7324 It is not necessary when using MS products, and will cause corruption of
7325 all documents that use 8-bit character sets other than Latin-1. It's mostly
7326 worthwhile for Europeans on non-MS platforms, if weird garbage characters
7327 sometimes appear on some pages, or user agents that don't correct for this on
7330 My version of Mozilla (ancient) shows litte square boxes for quote
7331 characters, and apostrophes on moronized pages. So many pages have this, I
7332 can read them fine now. HB 08/27/06
7339 <term><emphasis>shockwave-flash</emphasis></term>
7342 A filter for shockwave haters. As the name suggests, this filter strips code
7343 out of web pages that is used to embed shockwave flash objects.
7351 <term><emphasis>quicktime-kioskmode</emphasis></term>
7354 Change HTML code that embeds Quicktime objects so that kioskmode, which
7355 prevents saving, is disabled.
7361 <term><emphasis>fun</emphasis></term>
7364 Text replacements for subversive browsing fun. Make fun of your favorite
7365 Monopolist or play buzzword bingo.
7371 <term><emphasis>crude-parental</emphasis></term>
7374 A demonstration-only filter that shows how <application>Privoxy</application>
7375 can be used to delete web content on a keyword basis.
7381 <term><emphasis>ie-exploits</emphasis></term>
7384 An experimental collection of text replacements to disable malicious HTML and JavaScript
7385 code that exploits known security holes in Internet Explorer.
7388 Presently, it only protects against Nimda and a cross-site scripting bug, and
7389 would need active maintenance to provide more substantial protection.
7395 <term><emphasis>site-specifics</emphasis></term>
7398 Some web sites have very specific problems, the cure for which doesn't apply
7399 anywhere else, or could even cause damage on other sites.
7402 This is a collection of such site-specific cures which should only be applied
7403 to the sites they were intended for, which is what the supplied
7404 <filename>default.action</filename> file does. Users shouldn't need to change
7405 anything regarding this filter.
7411 <term><emphasis>google</emphasis></term>
7414 A CSS based block for Google text ads. Also removes a width limitation
7415 and the toolbar advertisement.
7421 <term><emphasis>yahoo</emphasis></term>
7424 Another CSS based block, this time for Yahoo text ads. And removes
7425 a width limitation as well.
7431 <term><emphasis>msn</emphasis></term>
7434 Another CSS based block, this time for MSN text ads. And removes
7435 tracking URLs, as well as a width limitation.
7441 <term><emphasis>blogspot</emphasis></term>
7444 Cleans up some Blogspot blogs. Read the fine print before using this one!
7447 This filter also intentionally removes some navigation stuff and sets the
7448 page width to 100%. As a result, some rounded <quote>corners</quote> would
7449 appear to early or not at all and as fixing this would require a browser
7450 that understands background-size (CSS3), they are removed instead.
7456 <term><emphasis>xml-to-html</emphasis></term>
7459 Server-header filter to change the Content-Type from xml to html.
7465 <term><emphasis>html-to-xml</emphasis></term>
7468 Server-header filter to change the Content-Type from html to xml.
7474 <term><emphasis>no-ping</emphasis></term>
7477 Removes the non-standard <literal>ping</literal> attribute from
7478 anchor and area HTML tags.
7484 <term><emphasis>hide-tor-exit-notation</emphasis></term>
7487 Client-header filter to remove the <command>Tor</command> exit node notation
7488 found in Host and Referer headers.
7491 If &my-app; and <command>Tor</command> are chained and &my-app;
7492 is configured to use socks4a, one can use <quote>http://www.example.org.foobar.exit/</quote>
7493 to access the host <quote>www.example.org</quote> through the
7494 <command>Tor</command> exit node <quote>foobar</quote>.
7497 As the HTTP client isn't aware of this notation, it treats the
7498 whole string <quote>www.example.org.foobar.exit</quote> as host and uses it
7499 for the <quote>Host</quote> and <quote>Referer</quote> headers. From the
7500 server's point of view the resulting headers are invalid and can cause problems.
7503 An invalid <quote>Referer</quote> header can trigger <quote>hot-linking</quote>
7504 protections, an invalid <quote>Host</quote> header will make it impossible for
7505 the server to find the right vhost (several domains hosted on the same IP address).
7508 This client-header filter removes the <quote>foo.exit</quote> part in those headers
7509 to prevent the mentioned problems. Note that it only modifies
7510 the HTTP headers, it doesn't make it impossible for the server
7511 to detect your <command>Tor</command> exit node based on the IP address
7512 the request is coming from.
7519 <term><emphasis> </emphasis></term>
7532 <!-- ~~~~~~~~ New section Header ~~~~~~~~~ -->
7533 <sect2 id="external-filter-syntax"><title>External filter syntax</title>
7535 External filters are scripts or programs that can modify the content in
7536 case common <literal><link linkend="filter">filters</link></literal>
7537 aren't powerful enough.
7540 External filters can be written in any language the platform &my-app; runs
7544 They are controlled with the
7545 <literal><link linkend="external-filter">external-filter</link></literal> action
7546 and have to be defined in the <literal><link linkend="filterfile">filterfile</link></literal>
7550 The header looks like any other filter, but instead of pcrs jobs, external
7551 filters contain a single job which can be a program or a shell script (which
7552 may call other scripts or programs).
7555 External filters read the content from STDIN and write the rewritten
7557 The environment variables PRIVOXY_URL, PRIVOXY_PATH, PRIVOXY_HOST,
7558 PRIVOXY_ORIGIN, PRIVOXY_LISTEN_ADDRESS can be used to get some details
7559 about the client request.
7562 &my-app; will temporary store the content to filter in the
7563 <literal><link linkend="temporary-directory">temporary-directory</link></literal>.
7567 EXTERNAL-FILTER: cat Pointless example filter that doesn't actually modify the content
7570 # Incorrect reimplementation of the filter above in POSIX shell.
7572 # Note that it's a single job that spans multiple lines, the line
7573 # breaks are not passed to the shell, thus the semicolons are required.
7575 # If the script isn't trivial, it is recommended to put it into an external file.
7577 # In general, writing external filters entirely in POSIX shell is not
7578 # considered a good idea.
7579 EXTERNAL-FILTER: cat2 Pointless example filter that despite its name may actually modify the content
7585 EXTERNAL-FILTER: rotate-image Rotate an image by 180 degree. Test filter with limited value.
7586 /usr/local/bin/convert - -rotate 180 -
7588 EXTERNAL-FILTER: citation-needed Adds a "[citation needed]" tag to an image. The coordinates may need adjustment.
7589 /usr/local/bin/convert - -pointsize 16 -fill white -annotate +17+418 "[citation needed]" -
7594 Currently external filters are executed with &my-app;'s privileges!
7595 Only use external filters you understand and trust.
7599 External filters are experimental and the syntax may change in the future.
7605 <!-- ~ End section ~ -->
7609 <!-- ~~~~~ New section ~~~~~ -->
7611 <sect1 id="templates">
7612 <title>Privoxy's Template Files</title>
7614 All <application>Privoxy</application> built-in pages, i.e. error pages such as the
7615 <ulink url="http://show-the-404-error.page"><quote>404 - No Such Domain</quote>
7616 error page</ulink>, the <ulink
7617 url="http://ads.bannerserver.example.com/nasty-ads/sponsor.html"><quote>BLOCKED</quote>
7619 and all pages of its <ulink url="http://config.privoxy.org/">web-based
7620 user interface</ulink>, are generated from <emphasis>templates</emphasis>.
7621 (<application>Privoxy</application> must be running for the above links to work as
7626 These templates are stored in a subdirectory of the <link linkend="confdir">configuration
7627 directory</link> called <filename>templates</filename>. On Unixish platforms,
7629 <ulink url="file:///etc/privoxy/templates/"><filename>/etc/privoxy/templates/</filename></ulink>.
7633 The templates are basically normal HTML files, but with place-holders (called symbols
7634 or exports), which <application>Privoxy</application> fills at run time. It
7635 is possible to edit the templates with a normal text editor, should you want
7636 to customize them. (<emphasis>Not recommended for the casual
7637 user</emphasis>). Should you create your own custom templates, you should use
7638 the <filename>config</filename> setting <link linkend="templdir">templdir</link>
7639 to specify an alternate location, so your templates do not get overwritten
7643 Note that just like in configuration files, lines starting
7644 with <literal>#</literal> are ignored when the templates are filled in.
7648 The place-holders are of the form <literal>@name@</literal>, and you will
7649 find a list of available symbols, which vary from template to template,
7650 in the comments at the start of each file. Note that these comments are not
7651 always accurate, and that it's probably best to look at the existing HTML
7652 code to find out which symbols are supported and what they are filled in with.
7656 A special application of this substitution mechanism is to make whole
7657 blocks of HTML code disappear when a specific symbol is set. We use this
7658 for many purposes, one of them being to include the beta warning in all
7659 our user interface (CGI) pages when <application>Privoxy</application>
7660 is in an alpha or beta development stage:
7664 <!-- @if-unstable-start -->
7666 ... beta warning HTML code goes here ...
7668 <!-- if-unstable-end@ --></screen>
7671 If the "unstable" symbol is set, everything in between and including
7672 <literal>@if-unstable-start</literal> and <literal>if-unstable-end@</literal>
7673 will disappear, leaving nothing but an empty comment:
7676 <screen><!-- --></screen>
7679 There's also an if-then-else construct and an <literal>#include</literal>
7680 mechanism, but you'll sure find out if you are inclined to edit the
7685 All templates refer to a style located at
7686 <ulink url="http://config.privoxy.org/send-stylesheet"><literal>http://config.privoxy.org/send-stylesheet</literal></ulink>.
7687 This is, of course, locally served by <application>Privoxy</application>
7688 and the source for it can be found and edited in the
7689 <filename>cgi-style.css</filename> template.
7694 <!-- ~ End section ~ -->
7698 <!-- ~~~~~ New section ~~~~~ -->
7700 <sect1 id="contact"><title>Contacting the Developers, Bug Reporting and Feature
7703 <!-- Include contacting.sgml boilerplate: -->
7705 <!-- end boilerplate -->
7709 <!-- ~ End section ~ -->
7712 <!-- ~~~~~ New section ~~~~~ -->
7713 <sect1 id="copyright"><title>Privoxy Copyright, License and History</title>
7715 <!-- Include copyright.sgml: -->
7717 <!-- end copyright -->
7720 <application>Privoxy</application> is free software; you can
7721 redistribute it and/or modify it under the terms of the
7722 <citetitle>GNU General Public License</citetitle>, version 2,
7723 as published by the Free Software Foundation and included in
7727 <!-- ~~~~~ New section ~~~~~ -->
7728 <sect2 id="license"><title>License</title>
7730 <screen><![ RCDATA [ &GPLv2; ]]></screen>
7733 <!-- ~ End section ~ -->
7736 <!-- ~~~~~ New section ~~~~~ -->
7738 <sect2 id="history"><title>History</title>
7739 <!-- Include history.sgml: -->
7741 <!-- end history -->
7744 <sect2 id="authors"><title>Authors</title>
7745 <!-- Include p-authors.sgml: -->
7747 <!-- end authors -->
7752 <!-- ~ End section ~ -->
7755 <!-- ~~~~~ New section ~~~~~ -->
7756 <sect1 id="seealso"><title>See Also</title>
7757 <!-- Include seealso.sgml: -->
7759 <!-- end seealso -->
7764 <!-- ~~~~~ New section ~~~~~ -->
7765 <sect1 id="appendix"><title>Appendix</title>
7768 <!-- ~~~~~ New section ~~~~~ -->
7770 <title>Regular Expressions</title>
7772 <application>Privoxy</application> uses Perl-style <quote>regular
7773 expressions</quote> in its <link linkend="actions-file">actions
7774 files</link> and <link linkend="filter-file">filter file</link>,
7775 through the <ulink url="http://www.pcre.org/">PCRE</ulink> and
7778 <ulink url="http://www.oesterhelt.org/pcrs/">PCRS</ulink> libraries.
7780 <application>PCRS</application> libraries.
7784 If you are reading this, you probably don't understand what <quote>regular
7785 expressions</quote> are, or what they can do. So this will be a very brief
7786 introduction only. A full explanation would require a <ulink
7787 url="http://www.oreilly.com/catalog/regex/">book</ulink> ;-)
7791 Regular expressions provide a language to describe patterns that can be
7792 run against strings of characters (letter, numbers, etc), to see if they
7793 match the string or not. The patterns are themselves (sometimes complex)
7794 strings of literal characters, combined with wild-cards, and other special
7795 characters, called meta-characters. The <quote>meta-characters</quote> have
7796 special meanings and are used to build complex patterns to be matched against.
7797 Perl Compatible Regular Expressions are an especially convenient
7798 <quote>dialect</quote> of the regular expression language.
7802 To make a simple analogy, we do something similar when we use wild-card
7803 characters when listing files with the <command>dir</command> command in DOS.
7804 <literal>*.*</literal> matches all filenames. The <quote>special</quote>
7805 character here is the asterisk which matches any and all characters. We can be
7806 more specific and use <literal>?</literal> to match just individual
7807 characters. So <quote>dir file?.text</quote> would match
7808 <quote>file1.txt</quote>, <quote>file2.txt</quote>, etc. We are pattern
7809 matching, using a similar technique to <quote>regular expressions</quote>!
7813 Regular expressions do essentially the same thing, but are much, much more
7814 powerful. There are many more <quote>special characters</quote> and ways of
7815 building complex patterns however. Let's look at a few of the common ones,
7816 and then some examples:
7821 <emphasis>.</emphasis> - Matches any single character, e.g. <quote>a</quote>,
7822 <quote>A</quote>, <quote>4</quote>, <quote>:</quote>, or <quote>@</quote>.
7828 <emphasis>?</emphasis> - The preceding character or expression is matched ZERO or ONE
7835 <emphasis>+</emphasis> - The preceding character or expression is matched ONE or MORE
7842 <emphasis>*</emphasis> - The preceding character or expression is matched ZERO or MORE
7849 <emphasis>\</emphasis> - The <quote>escape</quote> character denotes that
7850 the following character should be taken literally. This is used where one of the
7851 special characters (e.g. <quote>.</quote>) needs to be taken literally and
7852 not as a special meta-character. Example: <quote>example\.com</quote>, makes
7853 sure the period is recognized only as a period (and not expanded to its
7854 meta-character meaning of any single character).
7860 <emphasis>[ ]</emphasis> - Characters enclosed in brackets will be matched if
7861 any of the enclosed characters are encountered. For instance, <quote>[0-9]</quote>
7862 matches any numeric digit (zero through nine). As an example, we can combine
7863 this with <quote>+</quote> to match any digit one of more times: <quote>[0-9]+</quote>.
7869 <emphasis>( )</emphasis> - parentheses are used to group a sub-expression,
7870 or multiple sub-expressions.
7876 <emphasis>|</emphasis> - The <quote>bar</quote> character works like an
7877 <quote>or</quote> conditional statement. A match is successful if the
7878 sub-expression on either side of <quote>|</quote> matches. As an example:
7879 <quote>/(this|that) example/</quote> uses grouping and the bar character
7880 and would match either <quote>this example</quote> or <quote>that
7881 example</quote>, and nothing else.
7886 These are just some of the ones you are likely to use when matching URLs with
7887 <application>Privoxy</application>, and is a long way from a definitive
7888 list. This is enough to get us started with a few simple examples which may
7889 be more illuminating:
7893 <emphasis><literal>/.*/banners/.*</literal></emphasis> - A simple example
7894 that uses the common combination of <quote>.</quote> and <quote>*</quote> to
7895 denote any character, zero or more times. In other words, any string at all.
7896 So we start with a literal forward slash, then our regular expression pattern
7897 (<quote>.*</quote>) another literal forward slash, the string
7898 <quote>banners</quote>, another forward slash, and lastly another
7899 <quote>.*</quote>. We are building
7900 a directory path here. This will match any file with the path that has a
7901 directory named <quote>banners</quote> in it. The <quote>.*</quote> matches
7902 any characters, and this could conceivably be more forward slashes, so it
7903 might expand into a much longer looking path. For example, this could match:
7904 <quote>/eye/hate/spammers/banners/annoy_me_please.gif</quote>, or just
7905 <quote>/banners/annoying.html</quote>, or almost an infinite number of other
7906 possible combinations, just so it has <quote>banners</quote> in the path
7911 And now something a little more complex:
7915 <emphasis><literal>/.*/adv((er)?ts?|ertis(ing|ements?))?/</literal></emphasis> -
7916 We have several literal forward slashes again (<quote>/</quote>), so we are
7917 building another expression that is a file path statement. We have another
7918 <quote>.*</quote>, so we are matching against any conceivable sub-path, just so
7919 it matches our expression. The only true literal that <emphasis>must
7920 match</emphasis> our pattern is <application>adv</application>, together with
7921 the forward slashes. What comes after the <quote>adv</quote> string is the
7926 Remember the <quote>?</quote> means the preceding expression (either a
7927 literal character or anything grouped with <quote>(...)</quote> in this case)
7928 can exist or not, since this means either zero or one match. So
7929 <quote>((er)?ts?|ertis(ing|ements?))</quote> is optional, as are the
7930 individual sub-expressions: <quote>(er)</quote>,
7931 <quote>(ing|ements?)</quote>, and the <quote>s</quote>. The <quote>|</quote>
7932 means <quote>or</quote>. We have two of those. For instance,
7933 <quote>(ing|ements?)</quote>, can expand to match either <quote>ing</quote>
7934 <emphasis>OR</emphasis> <quote>ements?</quote>. What is being done here, is an
7935 attempt at matching as many variations of <quote>advertisement</quote>, and
7936 similar, as possible. So this would expand to match just <quote>adv</quote>,
7937 or <quote>advert</quote>, or <quote>adverts</quote>, or
7938 <quote>advertising</quote>, or <quote>advertisement</quote>, or
7939 <quote>advertisements</quote>. You get the idea. But it would not match
7940 <quote>advertizements</quote> (with a <quote>z</quote>). We could fix that by
7941 changing our regular expression to:
7942 <quote>/.*/adv((er)?ts?|erti(s|z)(ing|ements?))?/</quote>, which would then match
7947 <emphasis><literal>/.*/advert[0-9]+\.(gif|jpe?g)</literal></emphasis> - Again
7948 another path statement with forward slashes. Anything in the square brackets
7949 <quote>[ ]</quote> can be matched. This is using <quote>0-9</quote> as a
7950 shorthand expression to mean any digit one through nine. It is the same as
7951 saying <quote>0123456789</quote>. So any digit matches. The <quote>+</quote>
7952 means one or more of the preceding expression must be included. The preceding
7953 expression here is what is in the square brackets -- in this case, any digit
7954 one through nine. Then, at the end, we have a grouping: <quote>(gif|jpe?g)</quote>.
7955 This includes a <quote>|</quote>, so this needs to match the expression on
7956 either side of that bar character also. A simple <quote>gif</quote> on one side, and the other
7957 side will in turn match either <quote>jpeg</quote> or <quote>jpg</quote>,
7958 since the <quote>?</quote> means the letter <quote>e</quote> is optional and
7959 can be matched once or not at all. So we are building an expression here to
7960 match image GIF or JPEG type image file. It must include the literal
7961 string <quote>advert</quote>, then one or more digits, and a <quote>.</quote>
7962 (which is now a literal, and not a special character, since it is escaped
7963 with <quote>\</quote>), and lastly either <quote>gif</quote>, or
7964 <quote>jpeg</quote>, or <quote>jpg</quote>. Some possible matches would
7965 include: <quote>//advert1.jpg</quote>,
7966 <quote>/nasty/ads/advert1234.gif</quote>,
7967 <quote>/banners/from/hell/advert99.jpg</quote>. It would not match
7968 <quote>advert1.gif</quote> (no leading slash), or
7969 <quote>/adverts232.jpg</quote> (the expression does not include an
7970 <quote>s</quote>), or <quote>/advert1.jsp</quote> (<quote>jsp</quote> is not
7971 in the expression anywhere).
7975 We are barely scratching the surface of regular expressions here so that you
7976 can understand the default <application>Privoxy</application>
7977 configuration files, and maybe use this knowledge to customize your own
7978 installation. There is much, much more that can be done with regular
7979 expressions. Now that you know enough to get started, you can learn more on
7984 More reading on Perl Compatible Regular expressions:
7985 <ulink url="http://perldoc.perl.org/perlre.html">http://perldoc.perl.org/perlre.html</ulink>
7989 For information on regular expression based substitutions and their applications
7990 in filters, please see the <link linkend="filter-file">filter file tutorial</link>
7995 <!-- ~ End section ~ -->
7998 <!-- ~~~~~ New section ~~~~~ -->
7999 <sect2 id="internal-pages">
8000 <title>Privoxy's Internal Pages</title>
8003 Since <application>Privoxy</application> proxies each requested
8004 web page, it is easy for <application>Privoxy</application> to
8005 trap certain special URLs. In this way, we can talk directly to
8006 <application>Privoxy</application>, and see how it is
8007 configured, see how our rules are being applied, change these
8008 rules and other configuration options, and even turn
8009 <application>Privoxy's</application> filtering off, all with
8014 The URLs listed below are the special ones that allow direct access
8015 to <application>Privoxy</application>. Of course,
8016 <application>Privoxy</application> must be running to access these. If
8017 not, you will get a friendly error message. Internet access is not
8029 <ulink url="http://config.privoxy.org/">http://config.privoxy.org/</ulink>
8033 There is a shortcut: <ulink url="http://p.p/">http://p.p/</ulink> (But it
8034 doesn't provide a fall-back to a real page, in case the request is not
8035 sent through <application>Privoxy</application>)
8041 Show information about the current configuration, including viewing and
8042 editing of actions files:
8046 <ulink url="http://config.privoxy.org/show-status">http://config.privoxy.org/show-status</ulink>
8053 Show the browser's request headers:
8057 <ulink url="http://config.privoxy.org/show-request">http://config.privoxy.org/show-request</ulink>
8064 Show which actions apply to a URL and why:
8068 <ulink url="http://config.privoxy.org/show-url-info">http://config.privoxy.org/show-url-info</ulink>
8075 Toggle Privoxy on or off. This feature can be turned off/on in the main
8076 <filename>config</filename> file. When toggled <quote>off</quote>, <quote>Privoxy</quote>
8077 continues to run, but only as a pass-through proxy, with no actions taking
8082 <ulink url="http://config.privoxy.org/toggle">http://config.privoxy.org/toggle</ulink>
8086 Short cuts. Turn off, then on:
8090 <ulink url="http://config.privoxy.org/toggle?set=disable">http://config.privoxy.org/toggle?set=disable</ulink>
8095 <ulink url="http://config.privoxy.org/toggle?set=enable">http://config.privoxy.org/toggle?set=enable</ulink>
8105 <!-- ~~~~~ New section ~~~~~ -->
8107 <title>Chain of Events</title>
8109 Let's take a quick look at how some of <application>Privoxy's</application>
8110 core features are triggered, and the ensuing sequence of events when a web
8111 page is requested by your browser:
8117 First, your web browser requests a web page. The browser knows to send
8118 the request to <application>Privoxy</application>, which will in turn,
8119 relay the request to the remote web server after passing the following
8125 <application>Privoxy</application> traps any request for its own internal CGI
8126 pages (e.g <ulink url="http://p.p/">http://p.p/</ulink>) and sends the CGI page back to the browser.
8131 Next, <application>Privoxy</application> checks to see if the URL
8133 linkend="BLOCK"><quote>+block</quote></link> patterns. If
8134 so, the URL is then blocked, and the remote web server will not be contacted.
8135 <link linkend="HANDLE-AS-IMAGE"><quote>+handle-as-image</quote></link>
8137 <link linkend="HANDLE-AS-EMPTY-DOCUMENT"><quote>+handle-as-empty-document</quote></link>
8138 are then checked, and if there is no match, an
8139 HTML <quote>BLOCKED</quote> page is sent back to the browser. Otherwise, if
8140 it does match, an image is returned for the former, and an empty text
8141 document for the latter. The type of image would depend on the setting of
8142 <link linkend="SET-IMAGE-BLOCKER"><quote>+set-image-blocker</quote></link>
8143 (blank, checkerboard pattern, or an HTTP redirect to an image elsewhere).
8148 Untrusted URLs are blocked. If URLs are being added to the
8149 <filename>trust</filename> file, then that is done.
8154 If the URL pattern matches the <link
8155 linkend="FAST-REDIRECTS"><quote>+fast-redirects</quote></link> action,
8156 it is then processed. Unwanted parts of the requested URL are stripped.
8161 Now the rest of the client browser's request headers are processed. If any
8162 of these match any of the relevant actions (e.g. <link
8163 linkend="HIDE-USER-AGENT"><quote>+hide-user-agent</quote></link>,
8164 etc.), headers are suppressed or forged as determined by these actions and
8170 Now the web server starts sending its response back (i.e. typically a web
8176 First, the server headers are read and processed to determine, among other
8177 things, the MIME type (document type) and encoding. The headers are then
8178 filtered as determined by the
8179 <link linkend="CRUNCH-INCOMING-COOKIES"><quote>+crunch-incoming-cookies</quote></link>,
8180 <link linkend="SESSION-COOKIES-ONLY"><quote>+session-cookies-only</quote></link>,
8181 and <link linkend="DOWNGRADE-HTTP-VERSION"><quote>+downgrade-http-version</quote></link>
8187 If any <link linkend="FILTER"><quote>+filter</quote></link> action
8189 linkend="DEANIMATE-GIFS"><quote>+deanimate-gifs</quote></link>
8190 action applies (and the document type fits the action), the rest of the page is
8191 read into memory (up to a configurable limit). Then the filter rules (from
8192 <filename>default.filter</filename> and any other filter files) are
8193 processed against the buffered content. Filters are applied in the order
8194 they are specified in one of the filter files. Animated GIFs, if present,
8195 are reduced to either the first or last frame, depending on the action
8196 setting.The entire page, which is now filtered, is then sent by
8197 <application>Privoxy</application> back to your browser.
8200 If neither a <link linkend="FILTER"><quote>+filter</quote></link> action
8202 linkend="DEANIMATE-GIFS"><quote>+deanimate-gifs</quote></link>
8203 matches, then <application>Privoxy</application> passes the raw data through
8204 to the client browser as it becomes available.
8209 As the browser receives the now (possibly filtered) page content, it
8210 reads and then requests any URLs that may be embedded within the page
8211 source, e.g. ad images, stylesheets, JavaScript, other HTML documents (e.g.
8212 frames), sounds, etc. For each of these objects, the browser issues a
8213 separate request (this is easily viewable in <application>Privoxy's</application>
8214 logs). And each such request is in turn processed just as above. Note that a
8215 complex web page will have many, many such embedded URLs. If these
8216 secondary requests are to a different server, then quite possibly a very
8217 differing set of actions is triggered.
8224 NOTE: This is somewhat of a simplistic overview of what happens with each URL
8225 request. For the sake of brevity and simplicity, we have focused on
8226 <application>Privoxy's</application> core features only.
8232 <!-- ~~~~~ New section ~~~~~ -->
8233 <sect2 id="actionsanat">
8234 <title>Troubleshooting: Anatomy of an Action</title>
8237 The way <application>Privoxy</application> applies
8238 <link linkend="ACTIONS">actions</link> and <link linkend="FILTER">filters</link>
8239 to any given URL can be complex, and not always so
8240 easy to understand what is happening. And sometimes we need to be able to
8241 <emphasis>see</emphasis> just what <application>Privoxy</application> is
8242 doing. Especially, if something <application>Privoxy</application> is doing
8243 is causing us a problem inadvertently. It can be a little daunting to look at
8244 the actions and filters files themselves, since they tend to be filled with
8245 <link linkend="regex">regular expressions</link> whose consequences are not
8250 One quick test to see if <application>Privoxy</application> is causing a problem
8251 or not, is to disable it temporarily. This should be the first troubleshooting
8252 step (be sure to flush caches afterward!). Looking at the
8253 logs is a good idea too. (Note that both the toggle feature and logging are
8254 enabled via <filename>config</filename> file settings, and may need to be
8255 turned <quote>on</quote>.)
8258 Another easy troubleshooting step to try is if you have done any
8259 customization of your installation, revert back to the installed
8260 defaults and see if that helps. There are times the developers get complaints
8261 about one thing or another, and the problem is more related to a customized
8262 configuration issue.
8266 <application>Privoxy</application> also provides the
8267 <ulink url="http://config.privoxy.org/show-url-info">http://config.privoxy.org/show-url-info</ulink>
8268 page that can show us very specifically how <application>actions</application>
8269 are being applied to any given URL. This is a big help for troubleshooting.
8273 First, enter one URL (or partial URL) at the prompt, and then
8274 <application>Privoxy</application> will tell us
8275 how the current configuration will handle it. This will not
8276 help with filtering effects (i.e. the <link
8277 linkend="FILTER"><quote>+filter</quote></link> action) from
8278 one of the filter files since this is handled very
8279 differently and not so easy to trap! It also will not tell you about any other
8280 URLs that may be embedded within the URL you are testing. For instance, images
8281 such as ads are expressed as URLs within the raw page source of HTML pages. So
8282 you will only get info for the actual URL that is pasted into the prompt area
8283 -- not any sub-URLs. If you want to know about embedded URLs like ads, you
8284 will have to dig those out of the HTML source. Use your browser's <quote>View
8285 Page Source</quote> option for this. Or right click on the ad, and grab the
8290 Let's try an example, <ulink url="http://google.com">google.com</ulink>,
8291 and look at it one section at a time in a sample configuration (your real
8292 configuration may vary):
8296 Matches for http://www.google.com:
8298 In file: default.action <guibutton>[ View ]</guibutton> <guibutton>[ Edit ]</guibutton>
8300 {+change-x-forwarded-for{block}
8301 +deanimate-gifs {last}
8302 +fast-redirects {check-decoded-url}
8303 +filter {refresh-tags}
8304 +filter {img-reorder}
8305 +filter {banners-by-size}
8307 +filter {jumping-windows}
8308 +filter {ie-exploits}
8309 +hide-from-header {block}
8310 +hide-referrer {forge}
8311 +session-cookies-only
8312 +set-image-blocker {pattern}
8315 { -session-cookies-only }
8321 In file: user.action <guibutton>[ View ]</guibutton> <guibutton>[ Edit ]</guibutton>
8322 (no matches in this file)
8326 This is telling us how we have defined our
8327 <link linkend="ACTIONS"><quote>actions</quote></link>, and
8328 which ones match for our test case, <quote>google.com</quote>.
8329 Displayed is all the actions that are available to us. Remember,
8330 the <literal>+</literal> sign denotes <quote>on</quote>. <literal>-</literal>
8331 denotes <quote>off</quote>. So some are <quote>on</quote> here, but many
8332 are <quote>off</quote>. Each example we try may provide a slightly different
8333 end result, depending on our configuration directives.
8337 is for our <filename>default.action</filename> file. The large, multi-line
8338 listing, is how the actions are set to match for all URLs, i.e. our default
8339 settings. If you look at your <quote>actions</quote> file, this would be the
8340 section just below the <quote>aliases</quote> section near the top. This
8341 will apply to all URLs as signified by the single forward slash at the end
8342 of the listing -- <quote> / </quote>.
8346 But we have defined additional actions that would be exceptions to these general
8347 rules, and then we list specific URLs (or patterns) that these exceptions
8348 would apply to. Last match wins. Just below this then are two explicit
8349 matches for <quote>.google.com</quote>. The first is negating our previous
8350 cookie setting, which was for <link
8351 linkend="SESSION-COOKIES-ONLY"><quote>+session-cookies-only</quote></link>
8352 (i.e. not persistent). So we will allow persistent cookies for google, at
8353 least that is how it is in this example. The second turns
8354 <emphasis>off</emphasis> any <link
8355 linkend="FAST-REDIRECTS"><quote>+fast-redirects</quote></link>
8356 action, allowing this to take place unmolested. Note that there is a leading
8357 dot here -- <quote>.google.com</quote>. This will match any hosts and
8358 sub-domains, in the google.com domain also, such as
8359 <quote>www.google.com</quote> or <quote>mail.google.com</quote>. But it would not
8360 match <quote>www.google.de</quote>! So, apparently, we have these two actions
8361 defined as exceptions to the general rules at the top somewhere in the lower
8362 part of our <filename>default.action</filename> file, and
8363 <quote>google.com</quote> is referenced somewhere in these latter sections.
8367 Then, for our <filename>user.action</filename> file, we again have no hits.
8368 So there is nothing google-specific that we might have added to our own, local
8369 configuration. If there was, those actions would over-rule any actions from
8370 previously processed files, such as <filename>default.action</filename>.
8371 <filename>user.action</filename> typically has the last word. This is the
8372 best place to put hard and fast exceptions,
8376 And finally we pull it all together in the bottom section and summarize how
8377 <application>Privoxy</application> is applying all its <quote>actions</quote>
8378 to <quote>google.com</quote>:
8386 +change-x-forwarded-for{block}
8387 -client-header-filter{hide-tor-exit-notation}
8388 -content-type-overwrite
8389 -crunch-client-header
8390 -crunch-if-none-match
8391 -crunch-incoming-cookies
8392 -crunch-outgoing-cookies
8393 -crunch-server-header
8394 +deanimate-gifs {last}
8395 -downgrade-http-version
8398 -filter {content-cookies}
8399 -filter {all-popups}
8400 -filter {banners-by-link}
8401 -filter {tiny-textforms}
8402 -filter {frameset-borders}
8403 -filter {demoronizer}
8404 -filter {shockwave-flash}
8405 -filter {quicktime-kioskmode}
8407 -filter {crude-parental}
8408 -filter {site-specifics}
8409 -filter {js-annoyances}
8410 -filter {html-annoyances}
8411 +filter {refresh-tags}
8412 -filter {unsolicited-popups}
8413 +filter {img-reorder}
8414 +filter {banners-by-size}
8416 +filter {jumping-windows}
8417 +filter {ie-exploits}
8424 -handle-as-empty-document
8426 -hide-accept-language
8427 -hide-content-disposition
8428 +hide-from-header {block}
8429 -hide-if-modified-since
8430 +hide-referrer {forge}
8433 -overwrite-last-modified
8434 -prevent-compression
8436 -server-header-filter{xml-to-html}
8437 -server-header-filter{html-to-xml}
8438 -session-cookies-only
8439 +set-image-blocker {pattern}
8443 Notice the only difference here to the previous listing, is to
8444 <quote>fast-redirects</quote> and <quote>session-cookies-only</quote>,
8445 which are activated specifically for this site in our configuration,
8446 and thus show in the <quote>Final Results</quote>.
8450 Now another example, <quote>ad.doubleclick.net</quote>:
8454 { +block{Domains starts with "ad"} }
8457 { +block{Domain contains "ad"} }
8460 { +block{Doubleclick banner server} +handle-as-image }
8461 .[a-vx-z]*.doubleclick.net
8465 We'll just show the interesting part here - the explicit matches. It is
8466 matched three different times. Two <quote>+block{}</quote> sections,
8467 and a <quote>+block{} +handle-as-image</quote>,
8468 which is the expanded form of one of our aliases that had been defined as:
8469 <quote>+block-as-image</quote>. (<link
8470 linkend="ALIASES"><quote>Aliases</quote></link> are defined in
8471 the first section of the actions file and typically used to combine more
8476 Any one of these would have done the trick and blocked this as an unwanted
8477 image. This is unnecessarily redundant since the last case effectively
8478 would also cover the first. No point in taking chances with these guys
8479 though ;-) Note that if you want an ad or obnoxious
8480 URL to be invisible, it should be defined as <quote>ad.doubleclick.net</quote>
8481 is done here -- as both a <link
8482 linkend="BLOCK"><quote>+block{}</quote></link>
8483 <emphasis>and</emphasis> an
8484 <link linkend="HANDLE-AS-IMAGE"><quote>+handle-as-image</quote></link>.
8485 The custom alias <quote><literal>+block-as-image</literal></quote> just
8486 simplifies the process and make it more readable.
8490 One last example. Let's try <quote>http://www.example.net/adsl/HOWTO/</quote>.
8491 This one is giving us problems. We are getting a blank page. Hmmm ...
8495 Matches for http://www.example.net/adsl/HOWTO/:
8497 In file: default.action <guibutton>[ View ]</guibutton> <guibutton>[ Edit ]</guibutton>
8501 +change-x-forwarded-for{block}
8502 -client-header-filter{hide-tor-exit-notation}
8503 -content-type-overwrite
8504 -crunch-client-header
8505 -crunch-if-none-match
8506 -crunch-incoming-cookies
8507 -crunch-outgoing-cookies
8508 -crunch-server-header
8510 -downgrade-http-version
8511 +fast-redirects {check-decoded-url}
8513 -filter {content-cookies}
8514 -filter {all-popups}
8515 -filter {banners-by-link}
8516 -filter {tiny-textforms}
8517 -filter {frameset-borders}
8518 -filter {demoronizer}
8519 -filter {shockwave-flash}
8520 -filter {quicktime-kioskmode}
8522 -filter {crude-parental}
8523 -filter {site-specifics}
8524 -filter {js-annoyances}
8525 -filter {html-annoyances}
8526 +filter {refresh-tags}
8527 -filter {unsolicited-popups}
8528 +filter {img-reorder}
8529 +filter {banners-by-size}
8531 +filter {jumping-windows}
8532 +filter {ie-exploits}
8539 -handle-as-empty-document
8541 -hide-accept-language
8542 -hide-content-disposition
8543 +hide-from-header{block}
8544 +hide-referer{forge}
8546 -overwrite-last-modified
8547 +prevent-compression
8549 -server-header-filter{xml-to-html}
8550 -server-header-filter{html-to-xml}
8551 +session-cookies-only
8552 +set-image-blocker{blank} }
8555 { +block{Path contains "ads".} +handle-as-image }
8560 Ooops, the <quote>/adsl/</quote> is matching <quote>/ads</quote> in our
8561 configuration! But we did not want this at all! Now we see why we get the
8562 blank page. It is actually triggering two different actions here, and
8563 the effects are aggregated so that the URL is blocked, and &my-app; is told
8564 to treat the block as if it were an image. But this is, of course, all wrong.
8565 We could now add a new action below this (or better in our own
8566 <filename>user.action</filename> file) that explicitly
8567 <emphasis>un</emphasis> blocks (
8568 <link linkend="BLOCK"><quote>{-block}</quote></link>) paths with
8569 <quote>adsl</quote> in them (remember, last match in the configuration
8570 wins). There are various ways to handle such exceptions. Example:
8579 Now the page displays ;-)
8580 Remember to flush your browser's caches when making these kinds of changes to
8581 your configuration to insure that you get a freshly delivered page! Or, try
8582 using <literal>Shift+Reload</literal>.
8586 But now what about a situation where we get no explicit matches like
8591 { +block{Path starts with "ads".} +handle-as-image }
8596 That actually was very helpful and pointed us quickly to where the problem
8597 was. If you don't get this kind of match, then it means one of the default
8598 rules in the first section of <filename>default.action</filename> is causing
8599 the problem. This would require some guesswork, and maybe a little trial and
8600 error to isolate the offending rule. One likely cause would be one of the
8601 <link linkend="FILTER"><quote>+filter</quote></link> actions.
8602 These tend to be harder to troubleshoot.
8603 Try adding the URL for the site to one of aliases that turn off
8604 <link linkend="FILTER"><quote>+filter</quote></link>:
8610 .worldpay.com # for quietpc.com
8617 <quote><literal>{ shop }</literal></quote> is an <quote>alias</quote> that expands to
8618 <quote><literal>{ -filter -session-cookies-only }</literal></quote>.
8619 Or you could do your own exception to negate filtering:
8624 # Disable ALL filter actions for sites in this section
8631 This would turn off all filtering for these sites. This is best
8632 put in <filename>user.action</filename>, for local site
8633 exceptions. Note that when a simple domain pattern is used by itself (without
8634 the subsequent path portion), all sub-pages within that domain are included
8635 automatically in the scope of the action.
8639 Images that are inexplicably being blocked, may well be hitting the
8640 <link linkend="FILTER-BANNERS-BY-SIZE"><quote>+filter{banners-by-size}</quote></link>
8642 that images of certain sizes are ad banners (works well
8643 <emphasis>most of the time</emphasis> since these tend to be standardized).
8647 <quote><literal>{ fragile }</literal></quote> is an alias that disables most
8648 actions that are the most likely to cause trouble. This can be used as a
8649 last resort for problem sites.
8654 # Handle with care: easy to break
8656 mybank.example.com</screen>
8660 <emphasis>Remember to flush caches!</emphasis> Note that the
8661 <literal>mail.google</literal> reference lacks the TLD portion (e.g.
8662 <quote>.com</quote>). This will effectively match any TLD with
8663 <literal>google</literal> in it, such as <literal>mail.google.de.</literal>,
8667 If this still does not work, you will have to go through the remaining
8668 actions one by one to find which one(s) is causing the problem.
8677 This program is free software; you can redistribute it
8678 and/or modify it under the terms of the GNU General
8679 Public License as published by the Free Software
8680 Foundation; either version 2 of the License, or (at
8681 your option) any later version.
8683 This program is distributed in the hope that it will
8684 be useful, but WITHOUT ANY WARRANTY; without even the
8685 implied warranty of MERCHANTABILITY or FITNESS FOR A
8686 PARTICULAR PURPOSE. See the GNU General Public
8687 License for more details.
8689 The GNU General Public License should be included with
8690 this file. If not, you can view it at
8691 http://www.gnu.org/copyleft/gpl.html
8692 or write to the Free Software Foundation, Inc.,
8693 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,