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3 <!entity supported SYSTEM "supported.sgml">
4 <!entity newfeatures SYSTEM "newfeatures.sgml">
5 <!entity p-intro SYSTEM "privoxy.sgml">
6 <!entity seealso SYSTEM "seealso.sgml">
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15 <!entity config SYSTEM "p-config.sgml">
16 <!entity changelog SYSTEM "changelog.sgml">
17 <!entity p-version "3.0.34">
18 <!entity p-status "stable">
19 <!entity % p-authors-formal "INCLUDE"> <!-- include additional text, etc -->
20 <!entity % p-not-stable "IGNORE">
21 <!entity % p-stable "INCLUDE">
22 <!entity % p-text "IGNORE"> <!-- define we are not a text only doc -->
23 <!entity % p-doc "INCLUDE"> <!-- and we are a formal doc -->
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25 <!entity % user-man "IGNORE">
26 <!entity % config-file "IGNORE">
27 <!entity % p-supp-userman "IGNORE"> <!-- Omit some from supported.sgml -->
28 <!entity my-copy "©"> <!-- kludge for docbook2man -->
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31 <!entity my-app "<application>Privoxy</application>">
34 File : doc/source/user-manual.sgml
38 Copyright (C) 2001-2023 Privoxy Developers https://www.privoxy.org/
41 ========================================================================
42 NOTE: Please read developer-manual/documentation.html before touching
43 anything in this, or other Privoxy documentation.
44 ========================================================================
51 <title>Privoxy &p-version; User Manual</title>
55 <!-- Completely the wrong markup, but very little is allowed -->
56 <!-- in this part of an article. FIXME -->
57 <link linkend="copyright">Copyright</link> &my-copy; 2001-2023 by
58 <ulink url="https://www.privoxy.org/">Privoxy Developers</ulink>
64 Note: the following should generate a separate page, and a live link to it,
65 all nicely done. But it doesn't for some mysterious reason. Please leave
66 commented unless it can be fixed proper. For the time being, the
67 copyright/license declarations will be in their own sgml.
80 This is here to keep vim syntax file from breaking :/
81 If I knew enough to fix it, I would.
82 PLEASE DO NOT REMOVE! HB: hal@foobox.net
88 The <citetitle>Privoxy User Manual</citetitle> gives users information on how to
89 install, configure and use <ulink
90 url="https://www.privoxy.org/">Privoxy</ulink>.
93 <!-- Include privoxy.sgml boilerplate: -->
95 <!-- end privoxy.sgml -->
98 You can find the latest version of the <citetitle>Privoxy User Manual</citetitle> at <ulink
99 url="https://www.privoxy.org/user-manual/">https://www.privoxy.org/user-manual/</ulink>.
100 Please see the <link linkend="contact">Contact section</link> on how to
101 contact the developers.
108 <!-- ~~~~~ New section ~~~~~ -->
109 <sect1 label="1" id="introduction"><title>Introduction</title>
111 This documentation is included with the current &p-status; version of
112 <application>Privoxy</application>, &p-version;<![%p-not-stable;[,
113 and is mostly complete at this point. The most up to date reference for the
114 time being is still the comments in the source files and in the individual
115 configuration files. Development of a new version is currently nearing
116 completion, and includes significant changes and enhancements over
120 <!-- include only in non-stable versions -->
123 Since this is a &p-status; version, not all new features are well tested. This
124 documentation may be slightly out of sync as a result (especially with
125 <ulink url="https://www.privoxy.org/gitweb/?p=privoxy.git;a=summary">git sources</ulink>).
126 And there <emphasis>may be</emphasis> bugs, though hopefully
131 <!-- ~~~~~ New section ~~~~~ -->
132 <sect2 id="features"><title>Features</title>
134 In addition to the core
135 features of ad blocking and
136 <ulink url="https://en.wikipedia.org/wiki/Browser_cookie">cookie</ulink> management,
137 <application>Privoxy</application> provides many supplemental
138 features<![%p-not-stable;[, some of them currently under development]]>,
139 that give the end-user more control, more privacy and more freedom:
141 <!-- Include newfeatures.sgml boilerplate here: -->
143 <!-- end boilerplate -->
148 <!-- ~ End section ~ -->
151 <!-- ~~~~~ New section ~~~~~ -->
152 <sect1 id="installation"><title>Installation</title>
155 <application>Privoxy</application> is available both in convenient pre-compiled
156 packages for a wide range of operating systems, and as raw source code.
157 For most users, we recommend using the packages, which can be downloaded from our
158 <ulink url="https://sourceforge.net/projects/ijbswa/">Privoxy Project
164 On some platforms, the installer may remove previously installed versions, if
165 found. (See below for your platform). In any case <emphasis>be sure to backup
166 your old configuration if it is valuable to you.</emphasis> See the <link
167 linkend="upgradersnote">note to upgraders</link> section below.
170 <!-- ~~~~~ New section ~~~~~ -->
171 <sect2 id="installation-packages"><title>Binary Packages</title>
173 How to install the binary packages depends on your operating system:
176 <!-- XXX: The installation sections should be sorted -->
178 <!-- ~~~~~ New section ~~~~~ -->
179 <sect3 id="installation-deb"><title>Debian and Ubuntu</title>
181 DEBs can be installed with <literal>apt-get install privoxy</literal>,
182 and will use <filename>/etc/privoxy</filename> for the location of
187 <!-- ~~~~~ New section ~~~~~ -->
188 <sect3 id="installation-pack-win"><title>Windows</title>
191 Just double-click the installer, which will guide you through
192 the installation process. You will find the configuration files
193 in the same directory as you installed <application>Privoxy</application> in.
196 Version 3.0.5 beta introduced full <application>Windows</application> service
197 functionality. On Windows only, the <application>Privoxy</application>
198 program has two new command line arguments to install and uninstall
199 <application>Privoxy</application> as a <emphasis>service</emphasis>.
203 <term>Arguments:</term>
206 <replaceable class="parameter">--install</replaceable>[:<replaceable class="parameter">service_name</replaceable>]
209 <replaceable class="parameter">--uninstall</replaceable>[:<replaceable class="parameter">service_name</replaceable>]
215 After invoking <application>Privoxy</application> with
216 <command>--install</command>, you will need to bring up the
217 <application>Windows</application> service console to assign the user you
218 want <application>Privoxy</application> to run under, and whether or not you
219 want it to run whenever the system starts. You can start the
220 <application>Windows</application> services console with the following
221 command: <command>services.msc</command>. If you do not take the manual step
222 of modifying <application>Privoxy's</application> service settings, it will
223 not start. Note too that you will need to give Privoxy a user account that
224 actually exists, or it will not be permitted to
225 write to its log and configuration files.
230 <!-- ~~~~~ New section ~~~~~ -->
231 <sect3 id="installation-mac"><title>Mac OS X</title>
233 Installation instructions for the OS X platform depend upon whether
234 you downloaded a ready-built installation package (.pkg or .mpkg) or have
235 downloaded the source code.
238 <sect3 renderas="sect4" id="OS-X-install-from-package">
239 <title>Installation from ready-built package</title>
241 The downloaded file will either be a .pkg (for OS X 10.5 upwards) or a bzipped
242 .mpkg file (for OS X 10.4). The former can be double-clicked as is and the
243 installation will start; double-clicking the latter will unzip the .mpkg file
244 which can then be double-clicked to commence the installation.
247 The privoxy service will automatically start after a successful installation
248 (and thereafter every time your computer starts up) however you will need to
249 configure your web browser(s) to use it. To do so, configure them to use a
250 proxy for HTTP and HTTPS at the address 127.0.0.1:8118.
253 To prevent the privoxy service from automatically starting when your computer
254 starts up, remove or rename the file <literal>/Library/LaunchDaemons/org.ijbswa.privoxy.plist</literal>
255 (on OS X 10.5 and higher) or the folder named
256 <literal>/Library/StartupItems/Privoxy</literal> (on OS X 10.4 'Tiger').
259 To manually start or stop the privoxy service, use the scripts startPrivoxy.sh
260 and stopPrivoxy.sh supplied in /Applications/Privoxy. They must be run from an
261 administrator account, using sudo.
264 To uninstall, run /Applications/Privoxy/uninstall.command as sudo from an
265 administrator account.
268 <sect3 renderas="sect4" id="OS-X-install-from-source">
269 <title>Installation from source</title>
271 To build and install the Privoxy source code on OS X you will need to obtain
272 the macsetup module from the Privoxy Sourceforge CVS repository (refer to
273 Sourceforge help for details of how to set up a CVS client to have read-only
274 access to the repository). This module contains scripts that leverage the usual
275 open-source tools (available as part of Apple's free of charge Xcode
276 distribution or via the usual open-source software package managers for OS X
277 (MacPorts, Homebrew, Fink etc.) to build and then install the privoxy binary
278 and associated files. The macsetup module's README file contains complete
279 instructions for its use.
282 The privoxy service will automatically start after a successful installation
283 (and thereafter every time your computer starts up) however you will need to
284 configure your web browser(s) to use it. To do so, configure them to use a
285 proxy for HTTP and HTTPS at the address 127.0.0.1:8118.
288 To prevent the privoxy service from automatically starting when your computer
289 starts up, remove or rename the file <literal>/Library/LaunchDaemons/org.ijbswa.privoxy.plist</literal>
290 (on OS X 10.5 and higher) or the folder named
291 <literal>/Library/StartupItems/Privoxy</literal> (on OS X 10.4 'Tiger').
294 To manually start or stop the privoxy service, use the Privoxy Utility
295 for Mac OS X (also part of the macsetup module). This application can start
296 and stop the privoxy service and display its log and configuration files.
299 To uninstall, run the macsetup module's uninstall.sh as sudo from an
300 administrator account.
304 <!-- ~~~~~ New section ~~~~~ -->
305 <sect3 id="installation-freebsd"><title>FreeBSD and ElectroBSD</title>
308 Privoxy is part of FreeBSD's Ports Collection, you can build and install
309 it with <literal>cd /usr/ports/www/privoxy; make install clean</literal>.
315 <!-- ~~~~~ New section ~~~~~ -->
316 <sect2 id="installation-source"><title>Building from Source</title>
319 The most convenient way to obtain the <application>Privoxy</application> source
320 code is to download the source tarball from our
321 <ulink url="https://sourceforge.net/projects/ijbswa/files/Sources/">
322 project download page</ulink>,
323 or you can get the up-to-the-minute, possibly unstable, development version from
324 <ulink url="https://www.privoxy.org/">https://www.privoxy.org/</ulink>.
327 <!-- include buildsource.sgml boilerplate: -->
329 <!-- end boilerplate -->
332 <sect3 id="WINBUILD-CYGWIN"><title>Windows</title>
334 <sect4 id="WINBUILD-SETUP"><title>Setup</title>
336 Install the Cygwin utilities needed to build <application>Privoxy</application>.
337 If you have a 64 bit CPU (which most people do by now), get the
338 Cygwin setup-x86_64.exe program <ulink url="https://cygwin.com/setup-x86_64.exe">here</ulink>
339 (the .sig file is <ulink url="https://cygwin.com/setup-x86_64.exe.sig">here</ulink>).
342 Run the setup program and from View / Category select:
354 mingw64-i686-gcc-core
359 libxslt: GNOME XSLT library (runtime)
375 If you haven't already downloaded the Privoxy source code, get it now:
380 git clone https://www.privoxy.org/git/privoxy.git
384 Get the source code (.zip or .tar.gz) for tidy from
385 <ulink url="https://github.com/htacg/tidy-html5/releases">
386 https://github.com/htacg/tidy-html5/releases</ulink>,
387 unzip into <root-dir> and build the software:
391 cd tidy-html5-x.y.z/build/cmake
392 cmake ../.. -DCMAKE_BUILD_TYPE=Release -DBUILD_SHARED_LIB:BOOL=OFF -DCMAKE_INSTALL_PREFIX=/usr/local
397 If you want to be able to make a Windows release package, get the NSIS .zip file from
398 <!-- FIXME: which version(s) are known to work? -->
399 <ulink url="https://sourceforge.net/projects/nsis/files/NSIS%203/">
400 https://sourceforge.net/projects/nsis/files/NSIS%203/</ulink>
401 and extract the NSIS directory to <literal>/<root-dir>/nsis/</literal>.
402 Then edit the <filename>windows/GNUmakefile</filename> to set the location
403 of the NSIS executable - eg:
407 MAKENSIS = /<root-dir>/nsis/makensis.exe
411 Get the latest 8.x PCRE code from
412 <ulink url="https://sourceforge.net/projects/pcre/files/pcre/">PCRE
413 https://sourceforge.net/projects/pcre/files/pcre/</ulink>
414 and build the static PCRE libraries with
417 export CFLAGS="-O2 -fstack-protector-strong -D_FORTIFY_SOURCE=2"
418 export LDFLAGS="-fstack-protector-strong"
419 export CPPFLAGS="-DPCRE_STATIC"
421 ./configure --host=i686-w64-mingw32 \
422 --prefix=/usr/local/i686-w64-mingw32 \
423 --enable-utf --enable-unicode-properties \
425 --enable-newline-is-anycrlf \
428 --disable-pcregrep-libbz2 \
429 --disable-pcregrep-libz \
430 --disable-pcretest-libreadline \
431 --disable-stack-for-recursion \
432 --enable-static --disable-shared \
439 If you want to be able to have Privoxy do TLS Inspection, get the latest
440 2.28.x MBED-TLS library source code from
441 <ulink url="https://github.com/Mbed-TLS/mbedtls/tags">
442 https://github.com/Mbed-TLS/mbedtls/tags</ulink>,
443 extract the tar file into <literal><root-dir></literal>
444 and build the static libraries with
446 export WINDOWS_BUILD=1
447 # build for a Windows platform
451 export CC=i686-w64-mingw32-gcc
452 export LD=i686-w64-mingw32-gcc
453 export CFLAGS="-O2 -fstack-protector-strong -D_FORTIFY_SOURCE=2"
454 export LDFLAGS="${LDFLAGS} -fstack-protector-strong"
457 # build the libraries
463 Get the brotli library from
464 <ulink url="https://github.com/google/brotli/releases">
465 https://github.com/google/brotli/releases</ulink>
466 and build the static libraries with
469 # to create the GNU autotools files
473 export CFLAGS="-O2 -fstack-protector-strong -D_FORTIFY_SOURCE=2"
474 export LDFLAGS="${LDFLAGS} -fstack-protector-strong"
476 ./configure --host=i686-w64-mingw32 \
477 --prefix=/usr/local/i686-w64-mingw32 \
481 --disable-silent-rules \
490 <sect4 id="WINBUILD-BUILD"><title>Build</title>
493 To build just the Privoxy executable and not the whole installation package, do:
496 cd <root-dir>/privoxy
497 ./windows/MYconfigure && make
501 Privoxy uses the <ulink url="https://en.wikipedia.org/wiki/GNU_build_system">GNU Autotools</ulink>
502 for building software, so the process is:
505 autoheader # creates config.h.in
506 autoconf # uses config.h.in to create the configure shell script
507 ./configure [options] # creates GNUmakefile
508 make [options] # builds the program
512 The usual <literal>configure</literal> options for building a native Windows application under cygwin are
515 <literallayout class="Monospaced">
516 --host=i686-w64-mingw32
519 --enable-static-linking
526 You can set the <literal>CFLAGS</literal> and <literal>LDFLAGS</literal> envars before
527 running <literal>configure</literal> to set compiler and linker flags. For example:
531 $ export CFLAGS="-O2" # set gcc optimization level
532 $ export LDFLAGS="-Wl,--nxcompat" # Enable DEP
533 $ ./configure --host=i686-w64-mingw32 --enable-mingw32 --enable-zlib \
534 > --enable-static-linking --disable-pthread
535 $ make # build Privoxy
539 See the <ulink url="../developer-manual/newrelease.html#NEWRELEASE-WINDOWS">Developer's Manual</ulink>
540 for building a Windows release package.
548 <!-- ~~~~~ New section ~~~~~ -->
549 <sect2 id="installation-keepupdated"><title>Keeping your Installation Up-to-Date</title>
552 If you wish to receive an email notification whenever we release updates of
553 <application>Privoxy</application> or the actions file, <ulink
554 url="https://lists.privoxy.org/mailman/listinfo/privoxy-announce">subscribe
555 to our announce mailing list</ulink>, privoxy-announce@lists.privoxy.org.
559 In order not to lose your personal changes and adjustments when updating
560 to the latest <literal>default.action</literal> file we <emphasis>strongly
561 recommend</emphasis> that you use <literal>user.action</literal> and
562 <literal>user.filter</literal> for your local
563 customizations of <application>Privoxy</application>. See the <link
564 linkend="actions-file">Chapter on actions files</link> for details.
572 <!-- ~ End section ~ -->
574 <!-- ~~~~~ New section ~~~~~ -->
575 <sect1 id="whatsnew">
576 <title>What's New in this Release</title>
580 <!-- ~~~~~ New section ~~~~~ -->
582 <sect2 id="upgradersnote">
583 <title>Note to Upgraders</title>
586 A quick list of things to be aware of before upgrading from earlier
587 versions of <application>Privoxy</application>:
594 The recommended way to upgrade &my-app; is to backup your old
595 configuration files, install the new ones, verify that &my-app;
596 is working correctly and finally merge back your changes using
597 <application>diff</application> and maybe <application>patch</application>.
600 There are a number of new features in each &my-app; release and
601 most of them have to be explicitly enabled in the configuration
602 files. Old configuration files obviously don't do that and due
603 to syntax changes using old configuration files with a new
604 &my-app; isn't always possible anyway.
609 Note that some installers remove earlier versions completely,
610 including configuration files, therefore you should really save
611 any important configuration files!
616 On the other hand, other installers don't overwrite existing configuration
617 files, thinking you will want to do that yourself.
622 In the default configuration only fatal errors are logged now.
623 You can change that in the <link linkend="DEBUG">debug section</link>
624 of the configuration file. You may also want to enable more verbose
625 logging until you verified that the new &my-app; version is working
632 Three other config file settings are now off by default:
633 <link linkend="enable-remote-toggle">enable-remote-toggle</link>,
634 <link linkend="enable-remote-http-toggle">enable-remote-http-toggle</link>,
635 and <link linkend="enable-edit-actions">enable-edit-actions</link>.
636 If you use or want these, you will need to explicitly enable them, and
637 be aware of the security issues involved.
644 What constitutes a <quote>default</quote> configuration has changed,
645 and you may want to review which actions are <quote>on</quote> by
646 default. This is primarily a matter of emphasis, but some features
647 you may have been used to, may now be <quote>off</quote> by default.
648 There are also a number of new actions and filters you may want to
649 consider, most of which are not fully incorporated into the default
650 settings as yet (see above).
657 The default actions setting is now <literal>Cautious</literal>. Previous
658 releases had a default setting of <literal>Medium</literal>. Experienced
659 users may want to adjust this, as it is fairly conservative by &my-app;
660 standards and past practices. See <ulink
661 url="http://config.privoxy.org/edit-actions-list?f=default">
662 http://config.privoxy.org/edit-actions-list?f=default</ulink>. New users
663 should try the default settings for a while before turning up the volume.
669 The default setting has filtering turned <emphasis>off</emphasis>, which
670 subsequently means that compression is <emphasis>on</emphasis>. Remember
671 that filtering does not work on compressed pages, so if you use, or want to
672 use, filtering, you will need to force compression off. Example:
675 { +<link linkend="filter">filter</link>{google} +<link linkend="prevent-compression">prevent-compression</link> }
679 Or if you use a number of filters, or filter many sites, you may just want
680 to turn off compression for all sites in
681 <filename>default.action</filename> (or
682 <filename>user.action</filename>).
689 Also, <link linkend="SESSION-COOKIES-ONLY">session-cookies-only</link> is
690 off by default now. If you've liked this feature in the past, you may want
691 to turn it back on in <filename>user.action</filename> now.
698 Some installers may not automatically start
699 <application>Privoxy</application> after installation.
709 <!-- ~~~~~ New section ~~~~~ -->
710 <sect1 id="quickstart"><title>Quickstart to Using Privoxy</title>
716 Install <application>Privoxy</application>. See the <link
717 linkend="installation">Installation Section</link> below for platform specific
724 Advanced users and those who want to offer <application>Privoxy</application>
725 service to more than just their local machine should check the <link
726 linkend="config">main config file</link>, especially the <link
727 linkend="access-control">security-relevant</link> options. These are
734 Start <application>Privoxy</application>, if the installation program has
735 not done this already (may vary according to platform). See the section
736 <link linkend="startup">Starting <application>Privoxy</application></link>.
742 Set your browser to use <application>Privoxy</application> as HTTP and
743 HTTPS (SSL) <ulink url="https://en.wikipedia.org/wiki/Proxy_server">proxy</ulink>
744 by setting the proxy configuration for address of
745 <literal>127.0.0.1</literal> and port <literal>8118</literal>.
746 <emphasis>DO NOT</emphasis> activate proxying for <literal>FTP</literal> or
747 any protocols besides HTTP and HTTPS (SSL) unless you intend to prevent your
748 browser from using these protocols.
754 Flush your browser's disk and memory caches, to remove any cached ad images.
755 If using <application>Privoxy</application> to manage
756 <ulink url="https://en.wikipedia.org/wiki/Browser_cookie">cookies</ulink>,
757 you should remove any currently stored cookies too.
763 A default installation should provide a reasonable starting point for
764 most. There will undoubtedly be occasions where you will want to adjust the
765 configuration, but that can be dealt with as the need arises. Little
766 to no initial configuration is required in most cases, you may want
768 <ulink url="config.html#ENABLE-EDIT-ACTIONS">web-based action editor</ulink> though.
769 Be sure to read the warnings first.
772 See the <link linkend="configuration">Configuration section</link> for more
773 configuration options, and how to customize your installation.
774 You might also want to look at the <link
775 linkend="quickstart-ad-blocking">next section</link> for a quick
776 introduction to how <application>Privoxy</application> blocks ads and
783 If you experience ads that slip through, innocent images that are
784 blocked, or otherwise feel the need to fine-tune
785 <application>Privoxy's</application> behavior, take a look at the <link
786 linkend="actions-file">actions files</link>. As a quick start, you might
787 find the <link linkend="act-examples">richly commented examples</link>
788 helpful. You can also view and edit the actions files through the <ulink
789 url="http://config.privoxy.org">web-based user interface</ulink>. The
790 Appendix <quote><link linkend="actionsanat">Troubleshooting: Anatomy of an
791 Action</link></quote> has hints on how to understand and debug actions that
792 <quote>misbehave</quote>.
798 Please see the section <link linkend="contact">Contacting the
799 Developers</link> on how to report bugs, problems with websites or to get
806 Now enjoy surfing with enhanced control, comfort and privacy!
813 <!-- ~~~~~ New section ~~~~~ -->
815 <sect2 id="quickstart-ad-blocking">
816 <title>Quickstart to Ad Blocking</title>
818 NOTE: This section is deliberately redundant for those that don't
819 want to read the whole thing (which is getting lengthy).
822 Ad blocking is but one of <application>Privoxy's</application>
823 array of features. Many of these features are for the technically minded advanced
824 user. But, ad and banner blocking is surely common ground for everybody.
827 This section will provide a quick summary of ad blocking so
828 you can get up to speed quickly without having to read the more extensive
829 information provided below, though this is highly recommended.
832 First a bit of a warning ... blocking ads is much like blocking SPAM: the
833 more aggressive you are about it, the more likely you are to block
834 things that were not intended. And the more likely that some things
835 may not work as intended. So there is a trade off here. If you want
836 extreme ad free browsing, be prepared to deal with more
837 <quote>problem</quote> sites, and to spend more time adjusting the
838 configuration to solve these unintended consequences. In short, there is
839 not an easy way to eliminate <emphasis>all</emphasis> ads. Either take
840 the easy way and settle for <emphasis>most</emphasis> ads blocked with the
841 default configuration, or jump in and tweak it for your personal surfing
842 habits and preferences.
845 Secondly, a brief explanation of <application>Privoxy's </application>
846 <quote>actions</quote>. <quote>Actions</quote> in this context, are
847 the directives we use to tell <application>Privoxy</application> to perform
848 some task relating to HTTP transactions (i.e. web browsing). We tell
849 <application>Privoxy</application> to take some <quote>action</quote>. Each
850 action has a unique name and function. While there are many potential
851 <application>actions</application> in <application>Privoxy's</application>
852 arsenal, only a few are used for ad blocking. <link
853 linkend="actions">Actions</link>, and <link linkend="actions-file">action
854 configuration files</link>, are explained in depth below.
857 Actions are specified in <application>Privoxy's</application> configuration,
858 followed by one or more URLs to which the action should apply. URLs
859 can actually be URL type <link linkend="af-patterns">patterns</link> that use
860 wildcards so they can apply potentially to a range of similar URLs. The
861 actions, together with the URL patterns are called a section.
864 When you connect to a website, the full URL will either match one or more
865 of the sections as defined in <application>Privoxy's</application> configuration,
866 or not. If so, then <application>Privoxy</application> will perform the
867 respective actions. If not, then nothing special happens. Furthermore, web
868 pages may contain embedded, secondary URLs that your web browser will
869 use to load additional components of the page, as it parses the
870 original page's HTML content. An ad image for instance, is just an URL
871 embedded in the page somewhere. The image itself may be on the same server,
872 or a server somewhere else on the Internet. Complex web pages will have many
873 such embedded URLs. &my-app; can deal with each URL individually, so, for
874 instance, the main page text is not touched, but images from such-and-such
879 The most important actions for basic ad blocking are: <literal><link
880 linkend="block">block</link></literal>, <literal><link
881 linkend="handle-as-image">handle-as-image</link></literal>,
883 linkend="handle-as-empty-document">handle-as-empty-document</link></literal>,and
884 <literal><link linkend="set-image-blocker">set-image-blocker</link></literal>:
891 <literal><link linkend="block">block</link></literal> - this is perhaps
892 the single most used action, and is particularly important for ad blocking.
893 This action stops any contact between your browser and any URL patterns
894 that match this action's configuration. It can be used for blocking ads,
895 but also anything that is determined to be unwanted. By itself, it simply
896 stops any communication with the remote server and sends
897 <application>Privoxy</application>'s own built-in BLOCKED page instead to
898 let you now what has happened (with some exceptions, see below).
904 <literal><link linkend="handle-as-image">handle-as-image</link></literal> -
905 tells <application>Privoxy</application> to treat this URL as an image.
906 <application>Privoxy</application>'s default configuration already does this
907 for all common image types (e.g. GIF), but there are many situations where this
908 is not so easy to determine. So we'll force it in these cases. This is particularly
909 important for ad blocking, since only if we know that it's an image of
910 some kind, can we replace it with an image of our choosing, instead of the
911 <application>Privoxy</application> BLOCKED page (which would only result in
912 a <quote>broken image</quote> icon). There are some limitations to this
913 though. For instance, you can't just brute-force an image substitution for
914 an entire HTML page in most situations.
920 <literal><link linkend="handle-as-empty-document">handle-as-empty-document</link></literal> -
921 sends an empty document instead of <application>Privoxy's</application>
922 normal BLOCKED HTML page. This is useful for file types that are neither
923 HTML nor images, such as blocking JavaScript files.
930 linkend="set-image-blocker">set-image-blocker</link></literal> - tells
931 <application>Privoxy</application> what to display in place of an ad image that
932 has hit a block rule. For this to come into play, the URL must match a
933 <literal><link linkend="block">block</link></literal> action somewhere in the
934 configuration, <emphasis>and</emphasis>, it must also match an
935 <literal><link linkend="handle-as-image">handle-as-image</link></literal> action.
938 The configuration options on what to display instead of the ad are:
942 <emphasis>pattern</emphasis> - a checkerboard pattern, so that an ad
943 replacement is obvious. This is the default.
948 <emphasis>blank</emphasis> - A very small empty GIF image is displayed.
949 This is the so-called <quote>invisible</quote> configuration option.
954 <emphasis>http://<URL></emphasis> - A redirect to any image anywhere
955 of the user's choosing (advanced usage).
963 Advanced users will eventually want to explore &my-app;
964 <literal><link linkend="filter">filters</link></literal> as well. Filters
965 are very different from <literal><link
966 linkend="block">blocks</link></literal>.
967 A <quote>block</quote> blocks a site, page, or unwanted contented. Filters
968 are a way of filtering or modifying what is actually on the page. An example
969 filter usage: a text replacement of <quote>no-no</quote> for
970 <quote>nasty-word</quote>. That is a very simple example. This process can be
971 used for ad blocking, but it is more in the realm of advanced usage and has
972 some pitfalls to be wary off.
976 The quickest way to adjust any of these settings is with your browser through
977 the special <application>Privoxy</application> editor at <ulink
978 url="http://config.privoxy.org/show-status">http://config.privoxy.org/show-status</ulink>
979 (shortcut: <ulink url="http://p.p/">http://p.p/show-status</ulink>). This
980 is an internal page, and does not require Internet access.
984 Note that as of <application>Privoxy</application> 3.0.7 beta the
985 action editor is disabled by default. Check the
986 <ulink url="config.html#ENABLE-EDIT-ACTIONS">enable-edit-actions
987 section in the configuration file</ulink> to learn why and in which
988 cases it's safe to enable again.
992 If you decided to enable the action editor, select the appropriate
993 <quote>actions</quote> file, and click
994 <quote><guibutton>Edit</guibutton></quote>. It is best to put personal or
995 local preferences in <filename>user.action</filename> since this is not
996 meant to be overwritten during upgrades, and will over-ride the settings in
997 other files. Here you can insert new <quote>actions</quote>, and URLs for ad
998 blocking or other purposes, and make other adjustments to the configuration.
999 <application>Privoxy</application> will detect these changes automatically.
1003 A quick and simple step by step example:
1010 Right click on the ad image to be blocked, then select
1011 <quote><guimenuitem>Copy Link Location</guimenuitem></quote> from the
1019 url="http://config.privoxy.org/show-status">http://config.privoxy.org/show-status</ulink>
1024 Find <filename>user.action</filename> in the top section, and click
1025 on <quote><guibutton>Edit</guibutton></quote>:
1028 <!-- image of editor and actions files selections -->
1029 <figure pgwide="0" float="0"><title>Actions Files in Use</title>
1032 <imagedata fileref="files-in-use.jpg" format="jpg">
1035 <phrase>[ Screenshot of Actions Files in Use ]</phrase>
1043 You should have a section with only
1044 <literal><link linkend="block">block</link></literal> listed under
1045 <quote>Actions:</quote>.
1046 If not, click a <quote><guibutton>Insert new section below</guibutton></quote>
1047 button, and in the new section that just appeared, click the
1048 <guibutton>Edit</guibutton> button right under the word <quote>Actions:</quote>.
1049 This will bring up a list of all actions. Find
1050 <literal><link linkend="block">block</link></literal> near the top, and click
1051 in the <quote>Enabled</quote> column, then <quote><guibutton>Submit</guibutton></quote>
1052 just below the list.
1057 Now, in the <literal><link linkend="block">block</link></literal> actions section,
1058 click the <quote><guibutton>Add</guibutton></quote> button, and paste the URL the
1059 browser got from <quote><guimenuitem>Copy Link Location</guimenuitem></quote>.
1060 Remove the <literal>http://</literal> at the beginning of the URL. Then, click
1061 <quote><guibutton>Submit</guibutton></quote> (or
1062 <quote><guibutton>OK</guibutton></quote> if in a pop-up window).
1067 Now go back to the original page, and press <keycap>SHIFT-Reload</keycap>
1068 (or flush all browser caches). The image should be gone now.
1075 This is a very crude and simple example. There might be good reasons to use a
1076 wildcard pattern match to include potentially similar images from the same
1077 site. For a more extensive explanation of <quote>patterns</quote>, and
1078 the entire actions concept, see <link linkend="actions-file">the Actions
1083 For advanced users who want to hand edit their config files, you might want
1084 to now go to the <link linkend="act-examples">Actions Files Tutorial</link>.
1085 The ideas explained therein also apply to the web-based editor.
1088 There are also various
1089 <link linkend="filter">filters</link> that can be used for ad blocking
1090 (filters are a special subset of actions). These
1091 fall into the <quote>advanced</quote> usage category, and are explained in
1092 depth in later sections.
1099 <!-- ~ End section ~ -->
1102 <!-- ~~~~~ New section ~~~~~ -->
1103 <sect1 id="startup">
1104 <title>Starting Privoxy</title>
1106 Before launching <application>Privoxy</application> for the first time, you
1107 will want to configure your browser(s) to use
1108 <application>Privoxy</application> as a HTTP and HTTPS (SSL)
1109 <ulink url="https://en.wikipedia.org/wiki/Proxy_server">proxy</ulink>. The default is
1110 127.0.0.1 (or localhost) for the proxy address, and port 8118 (earlier versions
1111 used port 8000). This is the one configuration step <emphasis>that must be done
1115 Please note that <application>Privoxy</application> can only proxy HTTP and
1116 HTTPS traffic. It will not work with FTP or other protocols.
1119 <!-- image of Mozilla Proxy configuration -->
1120 <figure pgwide="0" float="0"><title>Proxy Configuration Showing
1121 Mozilla Firefox HTTP and HTTPS (SSL) Settings</title>
1124 <imagedata fileref="proxy_setup.jpg" format="jpg">
1127 <phrase>[ Screenshot of Mozilla Firefox Proxy Configuration ]</phrase>
1134 With <application>Firefox</application>, this is typically set under:
1138 <guibutton>Edit</guibutton> -> <guibutton>Preferences</guibutton> -> <guibutton>Network Settings</guibutton> -> <guibutton>Settings</guibutton>
1142 Or optionally on some platforms:
1146 <guibutton>Edit</guibutton> -> <guibutton>Preferences</guibutton> -> <guibutton>General</guibutton> -> <guibutton>Connection Settings</guibutton> -> <guibutton>Manual Proxy Configuration</guibutton>
1151 With <application>Netscape</application> (and
1152 <application>Mozilla</application>), this can be set under:
1157 <!-- Mix ascii and gui art, something for everybody -->
1158 <!-- spacing on this is tricky -->
1159 <guibutton>Edit</guibutton> -> <guibutton>Preferences</guibutton> -> <guibutton>Advanced</guibutton> -> <guibutton>Proxies</guibutton> -> <guibutton>HTTP Proxy</guibutton>
1163 For <application>Internet Explorer v.5-7</application>:
1167 <guibutton>Tools</guibutton> -> <guibutton>Internet Options</guibutton> -> <guibutton>Connections</guibutton> -> <guibutton>LAN Settings</guibutton>
1171 Then, check <quote>Use Proxy</quote> and fill in the appropriate info
1172 (Address: 127.0.0.1, Port: 8118). Include HTTPS (SSL), if you want HTTPS
1173 proxy support too (sometimes labeled <quote>Secure</quote>). Make sure any
1174 checkboxes like <quote>Use the same proxy server for all protocols</quote> is
1175 <emphasis>UNCHECKED</emphasis>. You want only HTTP and HTTPS (SSL)!
1178 <!-- image of IE Proxy configuration -->
1179 <figure pgwide="0" float="0"><title>Proxy Configuration Showing
1180 Internet Explorer HTTP and HTTPS (Secure) Settings</title>
1183 <imagedata fileref="proxy2.jpg" format="jpg">
1186 <phrase>[ Screenshot of IE Proxy Configuration ]</phrase>
1193 After doing this, flush your browser's disk and memory caches to force a
1194 re-reading of all pages and to get rid of any ads that may be cached. Remove
1195 any <ulink url="https://en.wikipedia.org/wiki/Browser_cookie">cookies</ulink>,
1196 if you want <application>Privoxy</application> to manage that. You are now
1197 ready to start enjoying the benefits of using
1198 <application>Privoxy</application>!
1202 <application>Privoxy</application> itself is typically started by specifying the
1203 main configuration file to be used on the command line. If no configuration
1204 file is specified on the command line, <application>Privoxy</application>
1205 will look for a file named <filename>config</filename> in the current
1206 directory. Except on Win32 where it will try <filename>config.txt</filename>.
1209 <sect2 id="start-debian">
1210 <title>Debian</title>
1212 We use a script. Note that Debian typically starts &my-app; upon booting per
1213 default. It will use the file
1214 <filename>/etc/privoxy/config</filename> as its main configuration
1218 # /etc/init.d/privoxy start
1222 <sect2 id="start-freebsd">
1223 <title>FreeBSD and ElectroBSD</title>
1225 To start <application>Privoxy</application> upon booting, add
1226 "privoxy_enable='YES'" to <filename>/etc/rc.conf</filename>.
1227 <application>Privoxy</application> will use
1228 <filename>/usr/local/etc/privoxy/config</filename> as its main
1232 If you installed <application>Privoxy</application> into a jail, the
1233 paths above are relative to the jail root.
1236 To start <application>Privoxy</application> manually, run:
1239 # service privoxy onestart
1243 <sect2 id="start-windows">
1244 <title>Windows</title>
1246 Click on the &my-app; Icon to start <application>Privoxy</application>. If no configuration file is
1247 specified on the command line, <application>Privoxy</application> will look
1248 for a file named <filename>config.txt</filename>. Note that Windows will
1249 automatically start &my-app; when the system starts if you chose that option
1253 <application>Privoxy</application> can run with full Windows service functionality.
1254 On Windows only, the &my-app; program has two new command line arguments
1255 to install and uninstall &my-app; as a service. See the
1256 <link linkend="installation-pack-win">Windows Installation
1257 instructions</link> for details.
1261 <sect2 id="start-unices">
1262 <title>Generic instructions for Unix derivates (Solaris, NetBSD, HP-UX etc.)</title>
1264 Example Unix startup command:
1267 # /usr/sbin/privoxy --user privoxy /etc/privoxy/config
1270 Note that if you installed <application>Privoxy</application> through
1271 a package manager, the package will probably contain a platform-specific
1272 script or configuration file to start <application>Privoxy</application>
1277 <sect2 id="start-macosx">
1278 <title>Mac OS X</title>
1280 The privoxy service will automatically start after a successful installation
1281 (and thereafter every time your computer starts up) however you will need to
1282 configure your web browser(s) to use it. To do so, configure them to use a
1283 proxy for HTTP and HTTPS at the address 127.0.0.1:8118.
1286 To prevent the privoxy service from automatically starting when your computer
1287 starts up, remove or rename the file <literal>/Library/LaunchDaemons/org.ijbswa.privoxy.plist</literal>
1288 (on OS X 10.5 and higher) or the folder named
1289 <literal>/Library/StartupItems/Privoxy</literal> (on OS X 10.4 'Tiger').
1292 To manually start or stop the privoxy service, use the scripts startPrivoxy.sh
1293 and stopPrivoxy.sh supplied in /Applications/Privoxy. They must be run from an
1294 administrator account, using sudo.
1302 See the section <link linkend="cmdoptions">Command line options</link> for
1306 must find a better place for this paragraph
1309 The included default configuration files should give a reasonable starting
1310 point. Most of the per site configuration is done in the
1311 <ulink url="actions-file.html"><quote>actions</quote></ulink> files. These are
1312 where various cookie actions are defined, ad and banner blocking, and other
1313 aspects of <application>Privoxy</application> configuration. There are several
1314 such files included, with varying levels of aggressiveness.
1318 You will probably want to keep an eye out for sites for which you may prefer
1319 persistent cookies, and add these to your actions configuration as needed. By
1320 default, most of these will be accepted only during the current browser
1321 session (aka <quote>session cookies</quote>), unless you add them to the
1322 configuration. If you want the browser to handle this instead, you will need
1323 to edit <filename>user.action</filename> (or through the web based interface)
1324 and disable this feature. If you use more than one browser, it would make
1325 more sense to let <application>Privoxy</application> handle this. In which
1326 case, the browser(s) should be set to accept all cookies.
1330 Another feature where you will probably want to define exceptions for trusted
1331 sites is the popup-killing (through <ulink
1332 url="actions-file.html#FILTER-POPUPS"><quote>+filter{popups}</quote></ulink>),
1333 because your favorite shopping, banking, or leisure site may need
1334 popups (explained below).
1338 <application>Privoxy</application> does not support all of the optional HTTP/1.1
1339 features yet. In the unlikely event that you experience inexplicable problems
1340 with browsers that use HTTP/1.1 per default
1341 (like <application>Mozilla</application> or recent versions of I.E.), you might
1342 try to force HTTP/1.0 compatibility. For Mozilla, look under <literal>Edit ->
1343 Preferences -> Debug -> Networking</literal>.
1344 Alternatively, set the <quote>+downgrade-http-version</quote> config option in
1345 <filename>default.action</filename> which will downgrade your browser's HTTP
1346 requests from HTTP/1.1 to HTTP/1.0 before processing them.
1350 After running <application>Privoxy</application> for a while, you can
1351 start to fine tune the configuration to suit your personal, or site,
1352 preferences and requirements. There are many, many aspects that can
1353 be customized. <quote>Actions</quote>
1354 can be adjusted by pointing your browser to
1355 <ulink url="http://config.privoxy.org/">http://config.privoxy.org/</ulink>
1356 (shortcut: <ulink url="http://p.p/">http://p.p/</ulink>),
1357 and then follow the link to <quote>View & Change the Current Configuration</quote>.
1358 (This is an internal page and does not require Internet access.)
1362 In fact, various aspects of <application>Privoxy</application>
1363 configuration can be viewed from this page, including
1364 current configuration parameters, source code version numbers,
1365 the browser's request headers, and <quote>actions</quote> that apply
1366 to a given URL. In addition to the actions file
1367 editor mentioned above, <application>Privoxy</application> can also
1368 be turned <quote>on</quote> and <quote>off</quote> (toggled) from this page.
1372 If you encounter problems, try loading the page without
1373 <application>Privoxy</application>. If that helps, enter the URL where
1374 you have the problems into <ulink url="http://p.p/show-url-info">the browser
1375 based rule tracing utility</ulink>. See which rules apply and why, and
1376 then try turning them off for that site one after the other, until the problem
1377 is gone. When you have found the culprit, you might want to turn the rest on
1382 If the above paragraph sounds gibberish to you, you might want to <link
1383 linkend="actions-file">read more about the actions concept</link>
1384 or even dive deep into the <link linkend="actionsanat">Appendix
1389 If you can't get rid of the problem at all, think you've found a bug in
1390 Privoxy, want to propose a new feature or smarter rules, please see the
1391 section <link linkend="contact"><quote>Contacting the
1392 Developers</quote></link> below.
1397 <!-- ~~~~~ New section ~~~~~ -->
1398 <sect2 id="cmdoptions">
1399 <title>Command Line Options</title>
1401 <application>Privoxy</application> may be invoked with the following
1402 command-line options:
1409 <emphasis>--config-test</emphasis>
1412 Exit after loading the configuration files before binding to
1413 the listen address. The exit code signals whether or not the
1414 configuration files have been successfully loaded.
1417 If the exit code is 1, at least one of the configuration files
1418 is invalid, if it is 0, all the configuration files have been
1419 successfully loaded (but may still contain errors that can
1420 currently only be detected at run time).
1423 This option doesn't affect the log setting, combination with
1424 <emphasis>--no-daemon</emphasis> is recommended if a configured
1425 log file shouldn't be used.
1430 <emphasis>--version</emphasis>
1433 Print version info and exit. Unix only.
1438 <emphasis>--help</emphasis>
1441 Print short usage info and exit. Unix only.
1446 <emphasis>--no-daemon</emphasis>
1449 Don't become a daemon, i.e. don't fork and become process group
1450 leader, and don't detach from controlling tty. Unix only.
1455 <emphasis>--pidfile FILE</emphasis>
1458 On startup, write the process ID to <emphasis>FILE</emphasis>. Delete the
1459 <emphasis>FILE</emphasis> on exit. Failure to create or delete the
1460 <emphasis>FILE</emphasis> is non-fatal. If no <emphasis>FILE</emphasis>
1461 option is given, no PID file will be used. Unix only.
1466 <emphasis>--user USER[.GROUP]</emphasis>
1469 After (optionally) writing the PID file, assume the user ID of
1470 <emphasis>USER</emphasis>, and if included the GID of GROUP. Exit if the
1471 privileges are not sufficient to do so. Unix only.
1476 <emphasis>--chroot</emphasis>
1479 Before changing to the user ID given in the <emphasis>--user</emphasis> option,
1480 chroot to that user's home directory, i.e. make the kernel pretend to the &my-app;
1481 process that the directory tree starts there. If set up carefully, this can limit
1482 the impact of possible vulnerabilities in &my-app; to the files contained in that hierarchy.
1488 <emphasis>--pre-chroot-nslookup hostname</emphasis>
1491 Specifies a hostname (for example www.privoxy.org) to look up before doing a chroot.
1492 On some systems, initializing the resolver library involves reading config files from
1493 /etc and/or loading additional shared libraries from /lib.
1494 On these systems, doing a hostname lookup before the chroot reduces
1495 the number of files that must be copied into the chroot tree.
1498 For fastest startup speed, a good value is a hostname that is not in /etc/hosts but that
1499 your local name server (listed in /etc/resolv.conf) can resolve without recursion
1500 (that is, without having to ask any other name servers). The hostname need not exist,
1501 but if it doesn't, an error message (which can be ignored) will be output.
1507 <emphasis>configfile</emphasis>
1510 If no <emphasis>configfile</emphasis> is included on the command line,
1511 <application>Privoxy</application> will look for a file named
1512 <quote>config</quote> in the current directory (except on Win32
1513 where it will look for <quote>config.txt</quote> instead). Specify
1514 full path to avoid confusion. If no config file is found,
1515 <application>Privoxy</application> will fail to start.
1522 On <application>MS Windows</application> only there are two additional
1523 command-line options to allow <application>Privoxy</application> to install and
1524 run as a <emphasis>service</emphasis>. See the
1525 <link linkend="installation-pack-win">Window Installation section</link>
1533 <!-- ~ End section ~ -->
1536 <!-- ~~~~~ New section ~~~~~ -->
1537 <sect1 id="configuration"><title>Privoxy Configuration</title>
1539 All <application>Privoxy</application> configuration is stored
1540 in text files. These files can be edited with a text editor.
1541 Many important aspects of <application>Privoxy</application> can
1542 also be controlled easily with a web browser.
1546 <!-- ~~~~~ New section ~~~~~ -->
1548 <sect2 id="control-with-webbrowser">
1549 <title>Controlling Privoxy with Your Web Browser</title>
1551 <application>Privoxy</application>'s user interface can be reached through the special
1552 URL <ulink url="http://config.privoxy.org/">http://config.privoxy.org/</ulink>
1553 (shortcut: <ulink url="http://p.p/">http://p.p/</ulink>),
1554 which is a built-in page and works without Internet access.
1555 You will see the following section:
1558 <!-- Needs to be put in a table and colorized -->
1559 <screen><!-- want the background color that goes with screen -->
1561 <bridgehead renderas="sect2"> Privoxy Menu</bridgehead>
1564 ▪ <ulink url="http://config.privoxy.org/show-status">View & change the current configuration</ulink>
1567 ▪ <ulink url="http://config.privoxy.org/client-tags">View or toggle the tags that can be set based on the client's address</ulink>
1570 ▪ <ulink url="http://config.privoxy.org/show-request">View the request headers.</ulink>
1573 ▪ <ulink url="http://config.privoxy.org/show-url-info">Look up which actions apply to a URL and why</ulink>
1576 ▪ <ulink url="http://config.privoxy.org/toggle">Toggle Privoxy on or off</ulink>
1579 ▪ <ulink
1580 url="https://www.privoxy.org/&p-version;/user-manual/">Documentation</ulink>
1588 This should be self-explanatory. Note the first item leads to an editor for the
1589 <link linkend="actions-file">actions files</link>, which is where the ad, banner,
1590 cookie, and URL blocking magic is configured as well as other advanced features of
1591 <application>Privoxy</application>. This is an easy way to adjust various
1592 aspects of <application>Privoxy</application> configuration. The actions
1593 file, and other configuration files, are explained in detail below.
1597 <quote>Toggle Privoxy On or Off</quote> is handy for sites that might
1598 have problems with your current actions and filters. You can in fact use
1599 it as a test to see whether it is <application>Privoxy</application>
1600 causing the problem or not. <application>Privoxy</application> continues
1601 to run as a proxy in this case, but all manipulation is disabled, i.e.
1602 <application>Privoxy</application> acts like a normal forwarding proxy.
1606 Note that several of the features described above are disabled by default
1607 in <application>Privoxy</application> 3.0.7 beta and later.
1609 <ulink url="config.html">configuration file</ulink> to learn why
1610 and in which cases it's safe to enable them again.
1615 <!-- ~ End section ~ -->
1620 <!-- ~~~~~ New section ~~~~~ -->
1622 <sect2 id="confoverview">
1623 <title>Configuration Files Overview</title>
1625 For Unix, *BSD and GNU/Linux, all configuration files are located in
1626 <filename>/etc/privoxy/</filename> by default. For MS Windows
1627 these are all in the same directory as the
1628 <application>Privoxy</application> executable. <![%p-not-stable;[ The name
1629 and number of configuration files has changed from previous versions, and is
1630 subject to change as development progresses.]]>
1634 The installed defaults provide a reasonable starting point, though
1635 some settings may be aggressive by some standards. For the time being, the
1636 principle configuration files are:
1643 The <link linkend="config">main configuration file</link> is named <filename>config</filename>
1644 on GNU/Linux, Unix, BSD, and <filename>config.txt</filename>
1645 on Windows. This is a required file.
1651 <filename>match-all.action</filename> is used to define which <quote>actions</quote>
1652 relating to banner-blocking, images, pop-ups, content modification, cookie handling
1653 etc should be applied by default. It should be the first actions file loaded.
1656 <filename>default.action</filename> defines many exceptions (both positive and negative)
1657 from the default set of actions that's configured in <filename>match-all.action</filename>.
1658 It should be the second actions file loaded and shouldn't be edited by the user.
1661 Multiple actions files may be defined in <filename>config</filename>. These
1662 are processed in the order they are defined. Local customizations and locally
1663 preferred exceptions to the default policies as defined in
1664 <filename>match-all.action</filename> (which you will most probably want
1665 to define sooner or later) are best applied in <filename>user.action</filename>,
1666 where you can preserve them across upgrades. The file isn't installed by all
1667 installers, but you can easily create it yourself with a text editor.
1670 There is also a web based editor that can be accessed from
1672 url="http://config.privoxy.org/show-status">http://config.privoxy.org/show-status</ulink>
1674 url="http://p.p/show-status">http://p.p/show-status</ulink>) for the
1675 various actions files.
1681 <quote>Filter files</quote> (the <link linkend="filter-file">filter
1682 file</link>) can be used to re-write the raw page content, including
1683 viewable text as well as embedded HTML and JavaScript, and whatever else
1684 lurks on any given web page. The filtering jobs are only pre-defined here;
1685 whether to apply them or not is up to the actions files.
1686 <filename>default.filter</filename> includes various filters made
1687 available for use by the developers. Some are much more intrusive than
1688 others, and all should be used with caution. You may define additional
1689 filter files in <filename>config</filename> as you can with
1690 actions files. We suggest <filename>user.filter</filename> for any
1691 locally defined filters or customizations.
1698 The syntax of the configuration and filter files may change between different
1699 Privoxy versions, unfortunately some enhancements cost backwards compatibility.
1700 <!-- Add link to documentation-->
1704 All files use the <quote><literal>#</literal></quote> character to denote a
1705 comment (the rest of the line will be ignored) and understand line continuation
1706 through placing a backslash ("<literal>\</literal>") as the very last character
1707 in a line. If the <literal>#</literal> is preceded by a backslash, it looses
1708 its special function. Placing a <literal>#</literal> in front of an otherwise
1709 valid configuration line to prevent it from being interpreted is called "commenting
1710 out" that line. Blank lines are ignored.
1714 The actions files and filter files
1715 can use Perl style <link linkend="regex">regular expressions</link> for
1716 maximum flexibility.
1720 After making any changes, there is no need to restart
1721 <application>Privoxy</application> in order for the changes to take
1722 effect. <application>Privoxy</application> detects such changes
1723 automatically. Note, however, that it may take one or two additional
1724 requests for the change to take effect. When changing the listening address
1725 of <application>Privoxy</application>, these <quote>wake up</quote> requests
1726 must obviously be sent to the <emphasis>old</emphasis> listening address.
1731 While under development, the configuration content is subject to change.
1732 The below documentation may not be accurate by the time you read this.
1733 Also, what constitutes a <quote>default</quote> setting, may change, so
1734 please check all your configuration files on important issues.
1740 <!-- ~ End section ~ -->
1743 <!-- ~~~~~~~~ New section Header ~~~~~~~~~ -->
1745 <!-- **************************************************** -->
1746 <!-- Include config.sgml here -->
1747 <!-- This is where the entire config file is detailed. -->
1749 <!-- end include -->
1752 <!-- ~ End section ~ -->
1756 <!-- ~~~~~~~~ New section Header ~~~~~~~~~ -->
1758 <sect1 id="actions-file"><title>Actions Files</title>
1762 XXX: similar descriptions are in the Configuration Files sections.
1763 We should only describe them at one place.
1766 The actions files are used to define what <emphasis>actions</emphasis>
1767 <application>Privoxy</application> takes for which URLs, and thus determines
1768 how ad images, cookies and various other aspects of HTTP content and
1769 transactions are handled, and on which sites (or even parts thereof).
1770 There are a number of such actions, with a wide range of functionality.
1771 Each action does something a little different.
1772 These actions give us a veritable arsenal of tools with which to exert
1773 our control, preferences and independence. Actions can be combined so that
1774 their effects are aggregated when applied against a given set of URLs.
1778 are three action files included with <application>Privoxy</application> with
1784 <filename>match-all.action</filename> - is used to define which
1785 <quote>actions</quote> relating to banner-blocking, images, pop-ups,
1786 content modification, cookie handling etc should be applied by default.
1787 It should be the first actions file loaded
1792 <filename>default.action</filename> - defines many exceptions (both
1793 positive and negative) from the default set of actions that's configured
1794 in <filename>match-all.action</filename>. It is a set of rules that should
1795 work reasonably well as-is for most users. This file is only supposed to
1796 be edited by the developers. It should be the second actions file loaded.
1801 <filename>user.action</filename> - is intended to be for local site
1802 preferences and exceptions. As an example, if your ISP or your bank
1803 has specific requirements, and need special handling, this kind of
1804 thing should go here. This file will not be upgraded.
1809 <guibutton>Edit</guibutton> <guibutton>Set to Cautious</guibutton> <guibutton>Set to Medium</guibutton> <guibutton>Set to Advanced</guibutton>
1812 These have increasing levels of aggressiveness <emphasis>and have no
1813 influence on your browsing unless you select them explicitly in the
1814 editor</emphasis>. A default installation should be pre-set to
1815 <literal>Cautious</literal>. New users should try this for a while before
1816 adjusting the settings to more aggressive levels. The more aggressive
1817 the settings, then the more likelihood there is of problems such as sites
1818 not working as they should.
1821 The <guibutton>Edit</guibutton> button allows you to turn each
1822 action on/off individually for fine-tuning. The <guibutton>Cautious</guibutton>
1823 button changes the actions list to low/safe settings which will activate
1824 ad blocking and a minimal set of &my-app;'s features, and subsequently
1825 there will be less of a chance for accidental problems. The
1826 <guibutton>Medium</guibutton> button sets the list to a medium level of
1827 other features and a low level set of privacy features. The
1828 <guibutton>Advanced</guibutton> button sets the list to a high level of
1829 ad blocking and medium level of privacy. See the chart below. The latter
1830 three buttons over-ride any changes via with the
1831 <guibutton>Edit</guibutton> button. More fine-tuning can be done in the
1832 lower sections of this internal page.
1835 While the actions file editor allows to enable these settings in all
1836 actions files, they are only supposed to be enabled in the first one
1837 to make sure you don't unintentionally overrule earlier rules.
1840 The default profiles, and their associated actions, as pre-defined in
1841 <filename>default.action</filename> are:
1843 <table frame=all id="default-configurations"><title>Default Configurations</title>
1844 <tgroup cols=4 align=left colsep=1 rowsep=1>
1845 <colspec colname=c1>
1846 <colspec colname=c2>
1847 <colspec colname=c3>
1848 <colspec colname=c4>
1851 <entry>Feature</entry>
1852 <entry>Cautious</entry>
1853 <entry>Medium</entry>
1854 <entry>Advanced</entry>
1859 <!-- <entry>f1</entry> -->
1860 <!-- <entry>f2</entry> -->
1861 <!-- <entry>f3</entry> -->
1862 <!-- <entry>f4</entry> -->
1868 <entry>Ad-blocking Aggressiveness</entry>
1869 <entry>medium</entry>
1875 <entry>Ad-filtering by size</entry>
1882 <entry>Ad-filtering by link</entry>
1888 <entry>Pop-up killing</entry>
1889 <entry>blocks only</entry>
1890 <entry>blocks only</entry>
1891 <entry>blocks only</entry>
1895 <entry>Privacy Features</entry>
1897 <entry>medium</entry>
1898 <entry>medium/high</entry>
1902 <entry>Cookie handling</entry>
1904 <entry>session-only</entry>
1909 <entry>Referer forging</entry>
1916 <entry>GIF de-animation</entry>
1923 <entry>Fast redirects</entry>
1930 <entry>HTML taming</entry>
1937 <entry>JavaScript taming</entry>
1944 <entry>Web-bug killing</entry>
1951 <entry>Image tag reordering</entry>
1965 The list of actions files to be used are defined in the main configuration
1966 file, and are processed in the order they are defined (e.g.
1967 <filename>default.action</filename> is typically processed before
1968 <filename>user.action</filename>). The content of these can all be viewed and
1970 url="http://config.privoxy.org/show-status">http://config.privoxy.org/show-status</ulink>.
1971 The over-riding principle when applying actions, is that the last action that
1972 matches a given URL wins. The broadest, most general rules go first
1973 (defined in <filename>default.action</filename>),
1974 followed by any exceptions (typically also in
1975 <filename>default.action</filename>), which are then followed lastly by any
1976 local preferences (typically in <emphasis>user</emphasis><filename>.action</filename>).
1977 Generally, <filename>user.action</filename> has the last word.
1981 An actions file typically has multiple sections. If you want to use
1982 <quote>aliases</quote> in an actions file, you have to place the (optional)
1983 <link linkend="aliases">alias section</link> at the top of that file.
1984 Then comes the default set of rules which will apply universally to all
1985 sites and pages (be <emphasis>very careful</emphasis> with using such a
1986 universal set in <filename>user.action</filename> or any other actions file after
1987 <filename>default.action</filename>, because it will override the result
1988 from consulting any previous file). And then below that,
1989 exceptions to the defined universal policies. You can regard
1990 <filename>user.action</filename> as an appendix to <filename>default.action</filename>,
1991 with the advantage that it is a separate file, which makes preserving your
1992 personal settings across <application>Privoxy</application> upgrades easier.
1996 Actions can be used to block anything you want, including ads, banners, or
1997 just some obnoxious URL whose content you would rather not see. Cookies can be accepted
1998 or rejected, or accepted only during the current browser session (i.e. not
1999 written to disk), content can be modified, some JavaScripts tamed, user-tracking
2000 fooled, and much more. See below for a <link linkend="actions">complete list
2004 <!-- ~~~~~ New section ~~~~~ -->
2005 <sect2 id="right-mix">
2006 <title>Finding the Right Mix</title>
2008 Note that some <link linkend="actions">actions</link>, like cookie suppression
2009 or script disabling, may render some sites unusable that rely on these
2010 techniques to work properly. Finding the right mix of actions is not always easy and
2011 certainly a matter of personal taste. And, things can always change, requiring
2012 refinements in the configuration. In general, it can be said that the more
2013 <quote>aggressive</quote> your default settings (in the top section of the
2014 actions file) are, the more exceptions for <quote>trusted</quote> sites you
2015 will have to make later. If, for example, you want to crunch all cookies per
2016 default, you'll have to make exceptions from that rule for sites that you
2017 regularly use and that require cookies for actually useful purposes, like maybe
2018 your bank, favorite shop, or newspaper.
2022 We have tried to provide you with reasonable rules to start from in the
2023 distribution actions files. But there is no general rule of thumb on these
2024 things. There just are too many variables, and sites are constantly changing.
2025 Sooner or later you will want to change the rules (and read this chapter again :).
2029 <!-- ~~~~~ New section ~~~~~ -->
2030 <sect2 id="how-to-edit">
2031 <title>How to Edit</title>
2033 The easiest way to edit the actions files is with a browser by
2034 using our browser-based editor, which can be reached from <ulink
2035 url="http://config.privoxy.org/show-status">http://config.privoxy.org/show-status</ulink>.
2036 Note: the config file option <link
2037 linkend="enable-edit-actions">enable-edit-actions</link> must be enabled for
2038 this to work. The editor allows both fine-grained control over every single
2039 feature on a per-URL basis, and easy choosing from wholesale sets of defaults
2040 like <quote>Cautious</quote>, <quote>Medium</quote> or
2041 <quote>Advanced</quote>. Warning: the <quote>Advanced</quote> setting is more
2042 aggressive, and will be more likely to cause problems for some sites.
2043 Experienced users only!
2047 If you prefer plain text editing to GUIs, you can of course also directly edit the
2048 the actions files with your favorite text editor. Look at
2049 <filename>default.action</filename> which is richly commented with many
2055 <sect2 id="actions-apply">
2056 <title>How Actions are Applied to Requests</title>
2058 Actions files are divided into sections. There are special sections,
2059 like the <quote><link linkend="aliases">alias</link></quote> sections which will
2060 be discussed later. For now let's concentrate on regular sections: They have a
2061 heading line (often split up to multiple lines for readability) which consist
2062 of a list of actions, separated by whitespace and enclosed in curly braces.
2063 Below that, there is a list of URL and tag patterns, each on a separate line.
2067 To determine which actions apply to a request, the URL of the request is
2068 compared to all URL patterns in each <quote>action file</quote>.
2069 Every time it matches, the list of applicable actions for the request is
2070 incrementally updated, using the heading of the section in which the
2071 pattern is located. The same is done again for tags and tag patterns later on.
2075 If multiple applying sections set the same action differently,
2076 the last match wins. If not, the effects are aggregated.
2077 E.g. a URL might match a regular section with a heading line of <literal>{
2078 +<link linkend="handle-as-image">handle-as-image</link> }</literal>,
2079 then later another one with just <literal>{
2080 +<link linkend="block">block</link> }</literal>, resulting
2081 in <emphasis>both</emphasis> actions to apply. And there may well be
2082 cases where you will want to combine actions together. Such a section then
2087 { +<literal>handle-as-image</literal> +<literal>block{Banner ads.}</literal> }
2088 # Block these as if they were images. Send no block page.
2090 media.example.com/.*banners
2091 .example.com/images/ads/
2095 You can trace this process for URL patterns and any given URL by visiting <ulink
2096 url="http://config.privoxy.org/show-url-info">http://config.privoxy.org/show-url-info</ulink>.
2100 Examples and more detail on this is provided in the Appendix, <link linkend="ACTIONSANAT">
2101 Troubleshooting: Anatomy of an Action</link> section.
2105 <!-- ~~~~~ New section ~~~~~ -->
2106 <sect2 id="af-patterns">
2107 <title>Patterns</title>
2109 As mentioned, <application>Privoxy</application> uses <quote>patterns</quote>
2110 to determine what <emphasis>actions</emphasis> might apply to which sites and
2111 pages your browser attempts to access. These <quote>patterns</quote> use wild
2112 card type <emphasis>pattern</emphasis> matching to achieve a high degree of
2113 flexibility. This allows one expression to be expanded and potentially match
2114 against many similar patterns.
2118 Generally, an URL pattern has the form
2119 <literal><host><port>/<path></literal>, where the
2120 <literal><host></literal>, the <literal><port></literal>
2121 and the <literal><path></literal> are optional. (This is why the special
2122 <literal>/</literal> pattern matches all URLs). Note that the protocol
2123 portion of the URL pattern (e.g. <literal>http://</literal>) should
2124 <emphasis>not</emphasis> be included in the pattern. This is assumed already!
2127 The pattern matching syntax is different for the host and path parts of
2128 the URL. The host part uses a simple globbing type matching technique,
2129 while the path part uses more flexible
2130 <ulink url="https://en.wikipedia.org/wiki/Regular_expressions"><quote>Regular
2131 Expressions</quote></ulink> (POSIX 1003.2).
2134 The port part of a pattern is a decimal port number preceded by a colon
2135 (<literal>:</literal>). If the host part contains a numerical IPv6 address,
2136 it has to be put into angle brackets
2137 (<literal><</literal>, <literal>></literal>).
2142 <term><literal>www.example.com/</literal></term>
2145 is a host-only pattern and will match any request to <literal>www.example.com</literal>,
2146 regardless of which document on that server is requested. So ALL pages in
2147 this domain would be covered by the scope of this action. Note that a
2148 simple <literal>example.com</literal> is different and would NOT match.
2153 <term><literal>www.example.com</literal></term>
2156 means exactly the same. For host-only patterns, the trailing <literal>/</literal> may
2162 <term><literal>www.example.com/index.html</literal></term>
2165 matches all the documents on <literal>www.example.com</literal>
2166 whose name starts with <literal>/index.html</literal>.
2171 <term><literal>www.example.com/index.html$</literal></term>
2174 matches only the single document <literal>/index.html</literal>
2175 on <literal>www.example.com</literal>.
2180 <term><literal>/index.html$</literal></term>
2183 matches the document <literal>/index.html</literal>, regardless of the domain,
2184 i.e. on <emphasis>any</emphasis> web server anywhere.
2189 <term><literal>/</literal></term>
2192 Matches any URL because there's no requirement for either the
2193 domain or the path to match anything.
2198 <term><literal>:8000/</literal></term>
2201 Matches any URL pointing to TCP port 8000.
2206 <term><literal>10.0.0.1/</literal></term>
2209 Matches any URL with the host address <literal>10.0.0.1</literal>.
2210 (Note that the real URL uses plain brackets, not angle brackets.)
2215 <term><literal><2001:db8::1>/</literal></term>
2218 Matches any URL with the host address <literal>2001:db8::1</literal>.
2219 (Note that the real URL uses plain brackets, not angle brackets.)
2224 <term><literal>index.html</literal></term>
2227 matches nothing, since it would be interpreted as a domain name and
2228 there is no top-level domain called <literal>.html</literal>. So its
2236 <!-- ~~~~~ New section ~~~~~ -->
2237 <sect3 id="host-pattern"><title>The Host Pattern</title>
2240 The matching of the host part offers some flexible options: if the
2241 host pattern starts or ends with a dot, it becomes unanchored at that end.
2242 The host pattern is often referred to as domain pattern as it is usually
2243 used to match domain names and not IP addresses.
2249 <term><literal>.example.com</literal></term>
2252 matches any domain with first-level domain <literal>com</literal>
2253 and second-level domain <literal>example</literal>.
2254 For example <literal>www.example.com</literal>,
2255 <literal>example.com</literal> and <literal>foo.bar.baz.example.com</literal>.
2256 Note that it wouldn't match if the second-level domain was <literal>another-example</literal>.
2261 <term><literal>www.</literal></term>
2264 matches any domain that <emphasis>STARTS</emphasis> with
2265 <literal>www.</literal> (It also matches the domain
2266 <literal>www</literal> but most of the time that doesn't matter.)
2271 <term><literal>.example.</literal></term>
2274 matches any domain that <emphasis>CONTAINS</emphasis> <literal>.example.</literal>.
2275 And, by the way, also included would be any files or documents that exist
2276 within that domain since no path limitations are specified. (Correctly
2277 speaking: It matches any FQDN that contains <literal>example</literal> as
2278 a domain.) This might be <literal>www.example.com</literal>,
2279 <literal>news.example.de</literal>, or
2280 <literal>www.example.net/cgi/testing.pl</literal> for instance. All these
2288 Additionally, there are wild-cards that you can use in the domain names
2289 themselves. These work similarly to shell globbing type wild-cards:
2290 <quote>*</quote> represents zero or more arbitrary characters (this is
2292 <ulink url="https://en.wikipedia.org/wiki/Regular_expressions"><quote>Regular
2293 Expression</quote></ulink> based syntax of <quote>.*</quote>),
2294 <quote>?</quote> represents any single character (this is equivalent to the
2295 regular expression syntax of a simple <quote>.</quote>), and you can define
2296 <quote>character classes</quote> in square brackets which is similar to
2297 the same regular expression technique. All of this can be freely mixed:
2302 <term><literal>ad*.example.com</literal></term>
2305 matches <quote>adserver.example.com</quote>,
2306 <quote>ads.example.com</quote>, etc but not <quote>sfads.example.com</quote>
2311 <term><literal>*ad*.example.com</literal></term>
2314 matches all of the above, and then some.
2319 <term><literal>.?pix.com</literal></term>
2322 matches <literal>www.ipix.com</literal>,
2323 <literal>pictures.epix.com</literal>, <literal>a.b.c.d.e.upix.com</literal> etc.
2328 <term><literal>www[1-9a-ez].example.c*</literal></term>
2331 matches <literal>www1.example.com</literal>,
2332 <literal>www4.example.cc</literal>, <literal>wwwd.example.cy</literal>,
2333 <literal>wwwz.example.com</literal> etc., but <emphasis>not</emphasis>
2334 <literal>wwww.example.com</literal>.
2341 While flexible, this is not the sophistication of full regular expression based syntax.
2345 When compiled with FEATURE_PCRE_HOST_PATTERNS patterns can be prefixed with
2346 <quote>PCRE-HOST-PATTERN:</quote> in which case full regular expression
2347 (PCRE) can be used for the host pattern as well.
2352 <!-- ~ End section ~ -->
2355 <!-- ~~~~~ New section ~~~~~ -->
2356 <sect3 id="path-pattern"><title>The Path Pattern</title>
2359 <application>Privoxy</application> uses <quote>modern</quote> POSIX 1003.2
2360 <ulink url="https://en.wikipedia.org/wiki/Regular_expressions"><quote>Regular
2361 Expressions</quote></ulink> for matching the path portion (after the slash),
2362 and is thus more flexible.
2366 There is an <link linkend="regex">Appendix</link> with a brief quick-start into regular
2367 expressions, you also might want to have a look at your operating system's documentation
2368 on regular expressions (try <literal>man re_format</literal>).
2372 Note that the path pattern is automatically left-anchored at the <quote>/</quote>,
2373 i.e. it matches as if it would start with a <quote>^</quote> (regular expression speak
2374 for the beginning of a line).
2378 Please also note that matching in the path is <emphasis>CASE INSENSITIVE</emphasis>
2379 by default, but you can switch to case sensitive at any point in the pattern by using the
2380 <quote>(?-i)</quote> switch: <literal>www.example.com/(?-i)PaTtErN.*</literal> will match
2381 only documents whose path starts with <literal>PaTtErN</literal> in
2382 <emphasis>exactly</emphasis> this capitalization.
2387 <term><literal>.example.com/.*</literal></term>
2390 Is equivalent to just <quote>.example.com</quote>, since any documents
2391 within that domain are matched with or without the <quote>.*</quote>
2392 regular expression. This is redundant
2397 <term><literal>.example.com/.*/index.html$</literal></term>
2400 Will match any page in the domain of <quote>example.com</quote> that is
2401 named <quote>index.html</quote>, and that is part of some path. For
2402 example, it matches <quote>www.example.com/testing/index.html</quote> but
2403 NOT <quote>www.example.com/index.html</quote> because the regular
2404 expression called for at least two <quote>/'s</quote>, thus the path
2405 requirement. It also would match
2406 <quote>www.example.com/testing/index_html</quote>, because of the
2407 special meta-character <quote>.</quote>.
2412 <term><literal>.example.com/(.*/)?index\.html$</literal></term>
2415 This regular expression is conditional so it will match any page
2416 named <quote>index.html</quote> regardless of path which in this case can
2417 have one or more <quote>/'s</quote>. And this one must contain exactly
2418 <quote>.html</quote> (and end with that!).
2423 <term><literal>.example.com/(.*/)(ads|banners?|junk)</literal></term>
2426 This regular expression will match any path of <quote>example.com</quote>
2427 that contains any of the words <quote>ads</quote>, <quote>banner</quote>,
2428 <quote>banners</quote> (because of the <quote>?</quote>) or <quote>junk</quote>.
2429 The path does not have to end in these words, just contain them.
2430 The path has to contain at least two slashes (including the one at the beginning).
2435 <term><literal>.example.com/(.*/)(ads|banners?|junk)/.*\.(jpe?g|gif|png)$</literal></term>
2438 This is very much the same as above, except now it must end in either
2439 <quote>.jpg</quote>, <quote>.jpeg</quote>, <quote>.gif</quote> or <quote>.png</quote>. So this
2440 one is limited to common image formats.
2447 There are many, many good examples to be found in <filename>default.action</filename>,
2448 and more tutorials below in <link linkend="regex">Appendix on regular expressions</link>.
2453 <!-- ~ End section ~ -->
2456 <!-- ~~~~~ New section ~~~~~ -->
2457 <sect3 id="tag-pattern"><title>The Request Tag Pattern</title>
2460 Request tag patterns are used to change the applying actions based on the
2461 request's tags. Tags can be created based on HTTP headers with either
2462 the <link linkend="CLIENT-HEADER-TAGGER">client-header-tagger</link>
2463 or the <link linkend="SERVER-HEADER-TAGGER">server-header-tagger</link> action.
2467 Request tag patterns have to start with <quote>TAG:</quote>, so &my-app;
2468 can tell them apart from other patterns. Everything after the colon
2469 including white space, is interpreted as a regular expression with
2470 path pattern syntax, except that tag patterns aren't left-anchored
2471 automatically (&my-app; doesn't silently add a <quote>^</quote>,
2472 you have to do it yourself if you need it).
2476 To match all requests that are tagged with <quote>foo</quote>
2477 your pattern line should be <quote>TAG:^foo$</quote>,
2478 <quote>TAG:foo</quote> would work as well, but it would also
2479 match requests whose tags contain <quote>foo</quote> somewhere.
2480 <quote>TAG: foo</quote> wouldn't work as it requires white space.
2484 Sections can contain URL and request tag patterns at the same time,
2485 but request tag patterns are checked after the URL patterns and thus
2486 always overrule them, even if they are located before the URL patterns.
2490 Once a new request tag is added, Privoxy checks right away if it's matched by one
2491 of the request tag patterns and updates the action settings accordingly. As a result
2492 request tags can be used to activate other tagger actions, as long as these other
2493 taggers look for headers that haven't already be parsed.
2497 For example you could tag client requests which use the
2498 <literal>POST</literal> method,
2499 then use this tag to activate another tagger that adds a tag if cookies
2500 are sent, and then use a block action based on the cookie tag. This allows
2501 the outcome of one action, to be input into a subsequent action. However if
2502 you'd reverse the position of the described taggers, and activated the
2503 method tagger based on the cookie tagger, no method tags would be created.
2504 The method tagger would look for the request line, but at the time
2505 the cookie tag is created, the request line has already been parsed.
2509 While this is a limitation you should be aware of, this kind of
2510 indirection is seldom needed anyway and even the example doesn't
2511 make too much sense.
2516 <!-- ~~~~~ New section ~~~~~ -->
2517 <sect3 id="negative-tag-patterns"><title>The Negative Request Tag Patterns</title>
2520 To match requests that do not have a certain request tag, specify a negative tag pattern
2521 by prefixing the tag pattern line with either <quote>NO-REQUEST-TAG:</quote>
2522 or <quote>NO-RESPONSE-TAG:</quote> instead of <quote>TAG:</quote>.
2526 Negative request tag patterns created with <quote>NO-REQUEST-TAG:</quote> are checked
2527 after all client headers are scanned, the ones created with <quote>NO-RESPONSE-TAG:</quote>
2528 are checked after all server headers are scanned. In both cases all the created
2529 tags are considered.
2533 <!-- ~~~~~ New section ~~~~~ -->
2534 <sect3 id="client-tag-pattern"><title>The Client Tag Pattern</title>
2536 <!-- XXX: This section contains duplicates content from the
2537 client-specific-tag documentation. -->
2540 Client tag patterns are not set based on HTTP headers but based on
2541 the client's IP address. Users can enable them themselves, but the
2542 Privoxy admin controls which tags are available and what their effect
2547 After a client-specific tag has been defined with the
2548 <link linkend="client-specific-tag">client-specific-tag</link>,
2549 directive, action sections can be activated based on the tag by using a
2550 CLIENT-TAG pattern. The CLIENT-TAG pattern is evaluated at the same priority
2551 as URL patterns, as a result the last matching pattern wins. Tags that
2552 are created based on client or server headers are evaluated later on
2553 and can overrule CLIENT-TAG and URL patterns!
2556 The tag is set for all requests that come from clients that requested
2557 it to be set. Note that "clients" are differentiated by IP address,
2558 if the IP address changes the tag has to be requested again.
2561 Clients can request tags to be set by using the CGI interface <ulink
2562 url="http://config.privoxy.org/client-tags">http://config.privoxy.org/client-tags</ulink>.
2570 # If the admin defined the client-specific-tag circumvent-blocks,
2571 # and the request comes from a client that previously requested
2572 # the tag to be set, overrule all previous +block actions that
2573 # are enabled based on URL to CLIENT-TAG patterns.
2575 CLIENT-TAG:^circumvent-blocks$
2577 # This section is not overruled because it's located after
2579 {+block{Nobody is supposed to request this.}}
2580 example.org/blocked-example-page</screen>
2586 <!-- ~ End section ~ -->
2589 <!-- ~~~~~ New section ~~~~~ -->
2591 <sect2 id="actions">
2592 <title>Actions</title>
2594 All actions are disabled by default, until they are explicitly enabled
2595 somewhere in an actions file. Actions are turned on if preceded with a
2596 <quote>+</quote>, and turned off if preceded with a <quote>-</quote>. So a
2597 <literal>+action</literal> means <quote>do that action</quote>, e.g.
2598 <literal>+block</literal> means <quote>please block URLs that match the
2599 following patterns</quote>, and <literal>-block</literal> means <quote>don't
2600 block URLs that match the following patterns, even if <literal>+block</literal>
2601 previously applied.</quote>
2605 Again, actions are invoked by placing them on a line, enclosed in curly braces and
2606 separated by whitespace, like in
2607 <literal>{+some-action -some-other-action{some-parameter}}</literal>,
2608 followed by a list of URL patterns, one per line, to which they apply.
2609 Together, the actions line and the following pattern lines make up a section
2610 of the actions file.
2614 Actions fall into three categories:
2620 Boolean, i.e the action can only be <quote>enabled</quote> or
2621 <quote>disabled</quote>. Syntax:
2624 +<replaceable class="function">name</replaceable> # enable action <replaceable class="parameter">name</replaceable>
2625 -<replaceable class="function">name</replaceable> # disable action <replaceable class="parameter">name</replaceable>
2628 Example: <literal>+handle-as-image</literal>
2635 Parameterized, where some value is required in order to enable this type of action.
2639 +<replaceable class="function">name</replaceable>{<replaceable class="parameter">param</replaceable>} # enable action and set parameter to <replaceable class="parameter">param</replaceable>,
2640 # overwriting parameter from previous match if necessary
2641 -<replaceable class="function">name</replaceable> # disable action. The parameter can be omitted
2644 Note that if the URL matches multiple positive forms of a parameterized action,
2645 the last match wins, i.e. the params from earlier matches are simply ignored.
2648 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>
2654 Multi-value. These look exactly like parameterized actions,
2655 but they behave differently: If the action applies multiple times to the
2656 same URL, but with different parameters, <emphasis>all</emphasis> the parameters
2657 from <emphasis>all</emphasis> matches are remembered. This is used for actions
2658 that can be executed for the same request repeatedly, like adding multiple
2659 headers, or filtering through multiple filters. Syntax:
2662 +<replaceable class="function">name</replaceable>{<replaceable class="parameter">param</replaceable>} # enable action and add <replaceable class="parameter">param</replaceable> to the list of parameters
2663 -<replaceable class="function">name</replaceable>{<replaceable class="parameter">param</replaceable>} # remove the parameter <replaceable class="parameter">param</replaceable> from the list of parameters
2664 # If it was the last one left, disable the action.
2665 <replaceable class="parameter">-name</replaceable> # disable this action completely and remove all parameters from the list
2668 Examples: <literal>+add-header{X-Fun-Header: Some text}</literal> and
2669 <literal>+filter{html-annoyances}</literal>
2676 If nothing is specified in any actions file, no <quote>actions</quote> are
2677 taken. So in this case <application>Privoxy</application> would just be a
2678 normal, non-blocking, non-filtering proxy. You must specifically enable the
2679 privacy and blocking features you need (although the provided default actions
2680 files will give a good starting point).
2684 Later defined action sections always over-ride earlier ones of the same type.
2685 So exceptions to any rules you make, should come in the latter part of the file (or
2686 in a file that is processed later when using multiple actions files such
2687 as <filename>user.action</filename>). For multi-valued actions, the actions
2688 are applied in the order they are specified. Actions files are processed in
2689 the order they are defined in <filename>config</filename> (the default
2690 installation has three actions files). It also quite possible for any given
2691 URL to match more than one <quote>pattern</quote> (because of wildcards and
2692 regular expressions), and thus to trigger more than one set of actions! Last
2696 <!-- start actions listing -->
2698 The list of valid <application>Privoxy</application> actions are:
2702 <!-- ********************************************************** -->
2703 <!-- Please note the below defined actions use id's that are -->
2704 <!-- probably linked from other places, so please don't change. -->
2706 <!-- ********************************************************** -->
2709 <!-- ~~~~~ New section ~~~~~ -->
2711 <sect3 renderas="sect4" id="add-header">
2712 <title>add-header</title>
2716 <term>Typical use:</term>
2718 <para>Confuse log analysis, custom applications</para>
2723 <term>Effect:</term>
2726 Sends a user defined HTTP header to the web server.
2733 <!-- boolean, parameterized, Multi-value -->
2735 <para>Multi-value.</para>
2740 <term>Parameter:</term>
2743 Any string value is possible. Validity of the defined HTTP headers is not checked.
2744 It is recommended that you use the <quote><literal>X-</literal></quote> prefix
2754 This action may be specified multiple times, in order to define multiple
2755 headers. This is rarely needed for the typical user. If you don't know what
2756 <quote>HTTP headers</quote> are, you definitely don't need to worry about this
2760 Headers added by this action are not modified by other actions.
2766 <term>Example usage:</term>
2768 <screen># Add a DNT ("Do not track") header to all requests,
2769 # event to those that already have one.
2771 # This is just an example, not a recommendation.
2773 # There is no reason to believe that user-tracking websites care
2774 # about the DNT header and depending on the User-Agent, adding the
2775 # header may make user-tracking easier.
2776 {+add-header{DNT: 1}}
2784 <!-- ~~~~~ New section ~~~~~ -->
2785 <sect3 renderas="sect4" id="block">
2786 <title>block</title>
2790 <term>Typical use:</term>
2792 <para>Block ads or other unwanted content</para>
2797 <term>Effect:</term>
2800 Requests for URLs to which this action applies are blocked, i.e. the
2801 requests are trapped by &my-app; and the requested URL is never retrieved,
2802 but is answered locally with a substitute page or image, as determined by
2804 linkend="handle-as-image">handle-as-image</link></literal>,
2806 linkend="set-image-blocker">set-image-blocker</link></literal>, and
2808 linkend="handle-as-empty-document">handle-as-empty-document</link></literal> actions.
2816 <!-- boolean, parameterized, Multi-value -->
2818 <para>Parameterized.</para>
2823 <term>Parameter:</term>
2825 <para>A block reason that should be given to the user.</para>
2833 <application>Privoxy</application> sends a special <quote>BLOCKED</quote> page
2834 for requests to blocked pages. This page contains the block reason given as
2835 parameter, a link to find out why the block action applies, and a click-through
2836 to the blocked content (the latter only if the force feature is available and
2840 A very important exception occurs if <emphasis>both</emphasis>
2841 <literal>block</literal> and <literal><link linkend="handle-as-image">handle-as-image</link></literal>,
2842 apply to the same request: it will then be replaced by an image. If
2843 <literal><link linkend="set-image-blocker">set-image-blocker</link></literal>
2844 (see below) also applies, the type of image will be determined by its parameter,
2845 if not, the standard checkerboard pattern is sent.
2848 It is important to understand this process, in order
2849 to understand how <application>Privoxy</application> deals with
2850 ads and other unwanted content. Blocking is a core feature, and one
2851 upon which various other features depend.
2854 The <literal><link linkend="filter">filter</link></literal>
2855 action can perform a very similar task, by <quote>blocking</quote>
2856 banner images and other content through rewriting the relevant URLs in the
2857 document's HTML source, so they don't get requested in the first place.
2858 Note that this is a totally different technique, and it's easy to confuse the two.
2864 <term>Example usage (section):</term>
2867 {+block{No nasty stuff for you.}}
2868 # Block and replace with "blocked" page
2869 .nasty-stuff.example.com
2871 {+block{Doubleclick banners.} +handle-as-image}
2872 # Block and replace with image
2876 {+block{Layered ads.} +handle-as-empty-document}
2877 # Block and then ignore
2878 adserver.example.net/.*\.js$
2888 <!-- ~~~~~ New section ~~~~~ -->
2889 <sect3 renderas="sect4" id="change-x-forwarded-for">
2890 <title>change-x-forwarded-for</title>
2894 <term>Typical use:</term>
2896 <para>Improve privacy by not forwarding the source of the request in the HTTP headers.</para>
2901 <term>Effect:</term>
2904 Deletes the <quote>X-Forwarded-For:</quote> HTTP header from the client request,
2912 <!-- Boolean, Parameterized, Multi-value -->
2914 <para>Parameterized.</para>
2919 <term>Parameter:</term>
2923 <para><quote>block</quote> to delete the header.</para>
2927 <quote>add</quote> to create the header (or append
2928 the client's IP address to an already existing one).
2939 It is safe and recommended to use <literal>block</literal>.
2942 Forwarding the source address of the request may make
2943 sense in some multi-user setups but is also a privacy risk.
2948 <term>Example usage:</term>
2950 <screen>+change-x-forwarded-for{block}</screen>
2956 <!-- ~~~~~ New section ~~~~~ -->
2957 <sect3 renderas="sect4" id="client-header-filter">
2958 <title>client-header-filter</title>
2962 <term>Typical use:</term>
2965 Rewrite or remove single client headers.
2971 <term>Effect:</term>
2974 All client headers to which this action applies are filtered on-the-fly through
2975 the specified regular expression based substitutions.
2982 <!-- boolean, parameterized, Multi-value -->
2984 <para>Multi-value.</para>
2989 <term>Parameter:</term>
2992 The name of a client-header filter, as defined in one of the
2993 <link linkend="filter-file">filter files</link>.
3002 Client-header filters are applied to each header on its own, not to
3003 all at once. This makes it easier to diagnose problems, but on the downside
3004 you can't write filters that only change header x if header y's value is z.
3005 You can do that by using tags though.
3008 Client-header filters are executed after the other header actions have finished
3009 and use their output as input.
3012 If the request URI gets changed, &my-app; will detect that and use the new
3013 one. This can be used to rewrite the request destination behind the client's
3014 back, for example to specify a Tor exit relay for certain requests.
3017 Note that to change the destination host for
3018 <link linkend="HTTPS-INSPECTION">https-inspected</link>
3019 requests a protocol and host has to be added to the URI.
3022 If <link linkend="HTTPS-INSPECTION">https inspection</link>
3023 is enabled, the protocol can be downgraded from https to http
3024 but upgrading a request from http to https is currently not
3028 After detecting a rewrite, &my-app; does not update the actions
3029 used for the request based on the new host.
3032 Please refer to the <link linkend="filter-file">filter file chapter</link>
3033 to learn which client-header filters are available by default, and how to
3041 <term>Example usage (section):</term>
3044 # Hide Tor exit notation in Host and Referer Headers
3045 {+client-header-filter{hide-tor-exit-notation}}
3054 <!-- ~~~~~ New section ~~~~~ -->
3055 <sect3 renderas="sect4" id="client-body-filter">
3056 <title>client-body-filter</title>
3060 <term>Typical use:</term>
3063 Rewrite or remove client request body.
3069 <term>Effect:</term>
3072 All request bodies to which this action applies are filtered on-the-fly through
3073 the specified regular expression based substitutions.
3080 <!-- boolean, parameterized, Multi-value -->
3082 <para>Multi-value.</para>
3087 <term>Parameter:</term>
3090 The name of a client-body filter, as defined in one of the
3091 <link linkend="filter-file">filter files</link>.
3100 Please refer to the <link linkend="filter-file">filter file chapter</link>
3101 to learn how to create your own client-body filters.
3104 The distribution <filename>default.filter</filename> file contains a selection of
3105 client-body filters for example purposes.
3108 The amount of data that can be filtered is limited by the
3109 <literal><link linkend="buffer-limit">buffer-limit</link></literal>
3110 option in the main <link linkend="config">config file</link>. The
3111 default is 4096 KB (4 Megs). Once this limit is exceeded, the whole
3112 request body is passed through unfiltered.
3118 <term>Example usage (section):</term>
3121 # Remove "test" everywhere in the request body
3122 {+client-body-filter{remove-test}}
3132 <!-- ~~~~~ New section ~~~~~ -->
3133 <sect3 renderas="sect4" id="client-body-tagger">
3134 <title>client-body-tagger</title>
3138 <term>Typical use:</term>
3141 Block requests based on the content of the body data.
3147 <term>Effect:</term>
3150 Client request bodies to which this action applies are filtered on-the-fly through
3151 the specified regular expression based substitutions, the result is used as tag.
3158 <!-- boolean, parameterized, Multi-value -->
3160 <para>Multi-value.</para>
3165 <term>Parameter:</term>
3168 The name of a client-body tagger, as defined in one of the
3169 <link linkend="filter-file">filter files</link>.
3178 Please refer to the <link linkend="filter-file">filter file chapter</link>
3179 to learn how to create your own client-body tagger.
3182 Client-body taggers are applied to each request body on its own,
3183 and as the body isn't modified, each tagger "sees" the original.
3186 Chunk-encoded request bodies currently can't be tagged.
3187 Request bodies larger than the buffer-limit can't be tagged either.
3193 <term>Example usage (section):</term>
3196 # Apply blafasel tagger.
3197 {+client-body-tagger{blafasel}}
3200 # Block request based on the tag created by the blafasel tagger.
3201 {+block{Request body contains blafasel}}
3202 TAG:^content contains blafasel$
3211 <!-- ~~~~~ New section ~~~~~ -->
3212 <sect3 renderas="sect4" id="client-header-tagger">
3213 <title>client-header-tagger</title>
3217 <term>Typical use:</term>
3220 Block requests based on their headers.
3226 <term>Effect:</term>
3229 Client headers to which this action applies are filtered on-the-fly through
3230 the specified regular expression based substitutions, the result is used as
3238 <!-- boolean, parameterized, Multi-value -->
3240 <para>Multi-value.</para>
3245 <term>Parameter:</term>
3248 The name of a client-header tagger, as defined in one of the
3249 <link linkend="filter-file">filter files</link>.
3258 Client-header taggers are applied to each header on its own,
3259 and as the header isn't modified, each tagger <quote>sees</quote>
3263 Client-header taggers are the first actions that are executed
3264 and their tags can be used to control every other action.
3270 <term>Example usage (section):</term>
3273 # Tag every request with the User-Agent header
3274 {+client-header-tagger{user-agent}}
3277 # Tagging itself doesn't change the action
3278 # settings, sections with TAG patterns do:
3280 # If it's a download agent, use a different forwarding proxy,
3281 # show the real User-Agent and make sure resume works.
3282 {+forward-override{forward-socks5 10.0.0.2:2222 .} \
3283 -hide-if-modified-since \
3284 -overwrite-last-modified \
3289 TAG:^User-Agent: NetBSD-ftp/
3290 TAG:^User-Agent: Novell ZYPP Installer
3291 TAG:^User-Agent: RPM APT-HTTP/
3292 TAG:^User-Agent: fetch libfetch/
3293 TAG:^User-Agent: Ubuntu APT-HTTP/
3294 TAG:^User-Agent: MPlayer/
3298 # Tag all requests with the Range header set
3299 {+client-header-tagger{range-requests}}
3302 # Disable filtering for the tagged requests.
3304 # With filtering enabled Privoxy would remove the Range headers
3305 # to be able to filter the whole response. The downside is that
3306 # it prevents clients from resuming downloads or skipping over
3307 # parts of multimedia files.
3308 {-filter -deanimate-gifs}
3313 # Tag all requests with the client IP address
3315 # (Technically the client IP address isn't included in the
3316 # client headers but client-header taggers can set it anyway.
3317 # For details see the tagger in default.filter)
3318 {+client-header-tagger{client-ip-address}}
3321 # Change forwarding settings for requests coming from address 10.0.0.1
3322 {+forward-override{forward-socks5 127.0.1.2:2222 .}}
3323 TAG:^IP-ADDRESS: 10\.0\.0\.1$
3332 <!-- ~~~~~ New section ~~~~~ -->
3333 <sect3 renderas="sect4" id="content-type-overwrite">
3334 <title>content-type-overwrite</title>
3338 <term>Typical use:</term>
3340 <para>Stop useless download menus from popping up, or change the browser's rendering mode</para>
3345 <term>Effect:</term>
3348 Replaces the <quote>Content-Type:</quote> HTTP server header.
3355 <!-- Boolean, Parameterized, Multi-value -->
3357 <para>Parameterized.</para>
3362 <term>Parameter:</term>
3374 The <quote>Content-Type:</quote> HTTP server header is used by the
3375 browser to decide what to do with the document. The value of this
3376 header can cause the browser to open a download menu instead of
3377 displaying the document by itself, even if the document's format is
3378 supported by the browser.
3381 The declared content type can also affect which rendering mode
3382 the browser chooses. If XHTML is delivered as <quote>text/html</quote>,
3383 many browsers treat it as yet another broken HTML document.
3384 If it is send as <quote>application/xml</quote>, browsers with
3385 XHTML support will only display it, if the syntax is correct.
3388 If you see a web site that proudly uses XHTML buttons, but sets
3389 <quote>Content-Type: text/html</quote>, you can use &my-app;
3390 to overwrite it with <quote>application/xml</quote> and validate
3391 the web master's claim inside your XHTML-supporting browser.
3392 If the syntax is incorrect, the browser will complain loudly.
3395 You can also go the opposite direction: if your browser prints
3396 error messages instead of rendering a document falsely declared
3397 as XHTML, you can overwrite the content type with
3398 <quote>text/html</quote> and have it rendered as broken HTML document.
3401 By default <literal>content-type-overwrite</literal> only replaces
3402 <quote>Content-Type:</quote> headers that look like some kind of text.
3403 If you want to overwrite it unconditionally, you have to combine it with
3404 <literal><link linkend="force-text-mode">force-text-mode</link></literal>.
3405 This limitation exists for a reason, think twice before circumventing it.
3408 Most of the time it's easier to replace this action with a custom
3409 <literal><link linkend="server-header-filter">server-header filter</link></literal>.
3410 It allows you to activate it for every document of a certain site and it will still
3411 only replace the content types you aimed at.
3414 Of course you can apply <literal>content-type-overwrite</literal>
3415 to a whole site and then make URL based exceptions, but it's a lot
3416 more work to get the same precision.
3422 <term>Example usage (sections):</term>
3424 <screen># Check if www.example.net/ really uses valid XHTML
3425 { +content-type-overwrite{application/xml} }
3428 # but leave the content type unmodified if the URL looks like a style sheet
3429 {-content-type-overwrite}
3430 www.example.net/.*\.css$
3431 www.example.net/.*style
3439 <!-- ~~~~~ New section ~~~~~ -->
3440 <sect3 renderas="sect4" id="crunch-client-header">
3444 <title>crunch-client-header</title>
3448 <term>Typical use:</term>
3450 <para>Remove a client header <application>Privoxy</application> has no dedicated action for.</para>
3455 <term>Effect:</term>
3458 Deletes every header sent by the client that contains the string the user supplied as parameter.
3465 <!-- Boolean, Parameterized, Multi-value -->
3467 <para>Parameterized.</para>
3472 <term>Parameter:</term>
3484 This action allows you to block client headers for which no dedicated
3485 <application>Privoxy</application> action exists.
3486 <application>Privoxy</application> will remove every client header that
3487 contains the string you supplied as parameter.
3490 Regular expressions are <emphasis>not supported</emphasis> and you can't
3491 use this action to block different headers in the same request, unless
3492 they contain the same string.
3495 <literal>crunch-client-header</literal> is only meant for quick tests.
3496 If you have to block several different headers, or only want to modify
3497 parts of them, you should use a
3498 <literal><link linkend="client-header-filter">client-header filter</link></literal>.
3502 Don't block any header without understanding the consequences.
3509 <term>Example usage (section):</term>
3511 <screen># Block the non-existent "Privacy-Violation:" client header
3512 { +crunch-client-header{Privacy-Violation:} }
3521 <!-- ~~~~~ New section ~~~~~ -->
3522 <sect3 renderas="sect4" id="crunch-if-none-match">
3523 <title>crunch-if-none-match</title>
3529 <term>Typical use:</term>
3531 <para>Prevent yet another way to track the user's steps between sessions.</para>
3536 <term>Effect:</term>
3539 Deletes the <quote>If-None-Match:</quote> HTTP client header.
3546 <!-- Boolean, Parameterized, Multi-value -->
3548 <para>Boolean.</para>
3553 <term>Parameter:</term>
3565 Removing the <quote>If-None-Match:</quote> HTTP client header
3566 is useful for filter testing, where you want to force a real
3567 reload instead of getting status code <quote>304</quote> which
3568 would cause the browser to use a cached copy of the page.
3571 It is also useful to make sure the header isn't used as a cookie
3572 replacement (unlikely but possible).
3575 Blocking the <quote>If-None-Match:</quote> header shouldn't cause any
3576 caching problems, as long as the <quote>If-Modified-Since:</quote> header
3577 isn't blocked or missing as well.
3580 It is recommended to use this action together with
3581 <literal><link linkend="hide-if-modified-since">hide-if-modified-since</link></literal>
3583 <literal><link linkend="overwrite-last-modified">overwrite-last-modified</link></literal>.
3589 <term>Example usage (section):</term>
3591 <screen># Let the browser revalidate cached documents but don't
3592 # allow the server to use the revalidation headers for user tracking.
3593 {+hide-if-modified-since{-60} \
3594 +overwrite-last-modified{randomize} \
3595 +crunch-if-none-match}
3604 <!-- ~~~~~ New section ~~~~~ -->
3605 <sect3 renderas="sect4" id="crunch-incoming-cookies">
3606 <title>crunch-incoming-cookies</title>
3610 <term>Typical use:</term>
3613 Prevent the web server from setting HTTP cookies on your system
3619 <term>Effect:</term>
3622 Deletes any <quote>Set-Cookie:</quote> HTTP headers from server replies.
3629 <!-- Boolean, Parameterized, Multi-value -->
3631 <para>Boolean.</para>
3636 <term>Parameter:</term>
3648 This action is only concerned with <emphasis>incoming</emphasis> HTTP cookies. For
3649 <emphasis>outgoing</emphasis> HTTP cookies, use
3650 <literal><link linkend="crunch-outgoing-cookies">crunch-outgoing-cookies</link></literal>.
3651 Use <emphasis>both</emphasis> to disable HTTP cookies completely.
3654 It makes <emphasis>no sense at all</emphasis> to use this action in conjunction
3655 with the <literal><link linkend="session-cookies-only">session-cookies-only</link></literal> action,
3656 since it would prevent the session cookies from being set. See also
3657 <literal><link linkend="filter-content-cookies">filter-content-cookies</link></literal>.
3663 <term>Example usage:</term>
3665 <screen>+crunch-incoming-cookies</screen>
3672 <!-- ~~~~~ New section ~~~~~ -->
3673 <sect3 renderas="sect4" id="crunch-server-header">
3674 <title>crunch-server-header</title>
3680 <term>Typical use:</term>
3682 <para>Remove a server header <application>Privoxy</application> has no dedicated action for.</para>
3687 <term>Effect:</term>
3690 Deletes every header sent by the server that contains the string the user supplied as parameter.
3697 <!-- Boolean, Parameterized, Multi-value -->
3699 <para>Parameterized.</para>
3704 <term>Parameter:</term>
3716 This action allows you to block server headers for which no dedicated
3717 <application>Privoxy</application> action exists. <application>Privoxy</application>
3718 will remove every server header that contains the string you supplied as parameter.
3721 Regular expressions are <emphasis>not supported</emphasis> and you can't
3722 use this action to block different headers in the same request, unless
3723 they contain the same string.
3726 <literal>crunch-server-header</literal> is only meant for quick tests.
3727 If you have to block several different headers, or only want to modify
3728 parts of them, you should use a custom
3729 <literal><link linkend="server-header-filter">server-header filter</link></literal>.
3733 Don't block any header without understanding the consequences.
3740 <term>Example usage (section):</term>
3742 <screen># Crunch server headers that try to prevent caching
3743 { +crunch-server-header{no-cache} }
3752 <!-- ~~~~~ New section ~~~~~ -->
3753 <sect3 renderas="sect4" id="crunch-outgoing-cookies">
3754 <title>crunch-outgoing-cookies</title>
3758 <term>Typical use:</term>
3761 Prevent the web server from reading any HTTP cookies from your system
3767 <term>Effect:</term>
3770 Deletes any <quote>Cookie:</quote> HTTP headers from client requests.
3777 <!-- Boolean, Parameterized, Multi-value -->
3779 <para>Boolean.</para>
3784 <term>Parameter:</term>
3796 This action is only concerned with <emphasis>outgoing</emphasis> HTTP cookies. For
3797 <emphasis>incoming</emphasis> HTTP cookies, use
3798 <literal><link linkend="crunch-incoming-cookies">crunch-incoming-cookies</link></literal>.
3799 Use <emphasis>both</emphasis> to disable HTTP cookies completely.
3802 It makes <emphasis>no sense at all</emphasis> to use this action in conjunction
3803 with the <literal><link linkend="session-cookies-only">session-cookies-only</link></literal> action,
3804 since it would prevent the session cookies from being read.
3810 <term>Example usage:</term>
3812 <screen>+crunch-outgoing-cookies</screen>
3820 <!-- ~~~~~ New section ~~~~~ -->
3821 <sect3 renderas="sect4" id="deanimate-gifs">
3822 <title>deanimate-gifs</title>
3826 <term>Typical use:</term>
3828 <para>Stop those annoying, distracting animated GIF images.</para>
3833 <term>Effect:</term>
3836 De-animate GIF animations, i.e. reduce them to their first or last image.
3843 <!-- boolean, parameterized, Multi-value -->
3845 <para>Parameterized.</para>
3850 <term>Parameter:</term>
3853 <quote>last</quote> or <quote>first</quote>
3862 This will also shrink the images considerably (in bytes, not pixels!). If
3863 the option <quote>first</quote> is given, the first frame of the animation
3864 is used as the replacement. If <quote>last</quote> is given, the last
3865 frame of the animation is used instead, which probably makes more sense for
3866 most banner animations, but also has the risk of not showing the entire
3867 last frame (if it is only a delta to an earlier frame).
3870 You can safely use this action with patterns that will also match non-GIF
3871 objects, because no attempt will be made at anything that doesn't look like
3878 <term>Example usage:</term>
3880 <screen>+deanimate-gifs{last}</screen>
3887 <!-- ~~~~~ New section ~~~~~ -->
3888 <sect3 renderas="sect4" id="delay-response">
3889 <title>delay-response</title>
3893 <term>Typical use:</term>
3895 <para>Delay responses to the client to reduce the load</para>
3900 <term>Effect:</term>
3903 Delays responses to the client by sending the response in ca. 10 byte chunks.
3910 <!-- boolean, parameterized, Multi-value -->
3912 <para>Parameterized.</para>
3917 <term>Parameter:</term>
3920 <quote>Number of milliseconds</quote>
3929 Sometimes when JavaScript code is used to fetch advertisements
3930 it doesn't respect Privoxy's blocks and retries to fetch the
3931 same resource again causing unnecessary load on the client.
3934 This action delays responses to the client and can be combined
3935 with <literal><link linkend="block">blocks</link></literal>
3936 to slow down the JavaScript code, thus reducing
3937 the load on the client.
3940 When used without <literal><link linkend="block">blocks</link></literal>
3941 the action can also be used to simulate a slow internet connection.
3947 <term>Example usage:</term>
3949 <screen>+delay-response{100}</screen>
3956 <!-- ~~~~~ New section ~~~~~ -->
3957 <sect3 renderas="sect4" id="downgrade-http-version">
3958 <title>downgrade-http-version</title>
3962 <term>Typical use:</term>
3964 <para>Work around (very rare) problems with HTTP/1.1</para>
3969 <term>Effect:</term>
3972 Downgrades HTTP/1.1 client requests and server replies to HTTP/1.0.
3979 <!-- boolean, parameterized, Multi-value -->
3981 <para>Boolean.</para>
3986 <term>Parameter:</term>
3998 This is a left-over from the time when <application>Privoxy</application>
3999 didn't support important HTTP/1.1 features well. It is left here for the
4000 unlikely case that you experience HTTP/1.1-related problems with some server
4004 Note that enabling this action is only a workaround. It should not
4005 be enabled for sites that work without it. While it shouldn't break
4006 any pages, it has an (usually negative) performance impact.
4009 If you come across a site where enabling this action helps, please report it,
4010 so the cause of the problem can be analyzed. If the problem turns out to be
4011 caused by a bug in <application>Privoxy</application> it should be
4012 fixed so the following release works without the work around.
4018 <term>Example usage (section):</term>
4020 <screen>{+downgrade-http-version}
4021 problem-host.example.com</screen>
4029 <!-- ~~~~~ New section ~~~~~ -->
4030 <sect3 renderas="sect4" id="external-filter">
4031 <title>external-filter</title>
4035 <term>Typical use:</term>
4037 <para>Modify content using a programming language of your choice.</para>
4042 <term>Effect:</term>
4045 All instances of text-based type, most notably HTML and JavaScript, to which
4046 this action applies, can be filtered on-the-fly through the specified external
4048 By default plain text documents are exempted from filtering, because web
4049 servers often use the <literal>text/plain</literal> MIME type for all files
4050 whose type they don't know.)
4057 <!-- boolean, parameterized, Multi-value -->
4059 <para>Multi-value.</para>
4064 <term>Parameter:</term>
4067 The name of an external content filter, as defined in the
4068 <link linkend="filter-file">filter file</link>.
4069 External filters can be defined in one or more files as defined by the
4070 <literal><link linkend="filterfile">filterfile</link></literal>
4071 option in the <link linkend="config">config file</link>.
4074 When used in its negative form,
4075 and without parameters, <emphasis>all</emphasis> filtering with external
4076 filters is completely disabled.
4085 External filters are scripts or programs that can modify the content in
4086 case common <literal><link linkend="filter">filters</link></literal>
4087 aren't powerful enough. With the exception that this action doesn't
4088 use pcrs-based filters, the notes in the
4089 <literal><link linkend="filter">filter</link></literal> section apply.
4093 Currently external filters are executed with &my-app;'s privileges.
4094 Only use external filters you understand and trust.
4098 This feature is experimental, the <literal><link
4099 linkend="external-filter-syntax">syntax</link></literal>
4100 may change in the future.
4107 <term>Example usage:</term>
4109 <screen>+external-filter{fancy-filter}</screen>
4115 <!-- ~~~~~ New section ~~~~~ -->
4116 <sect3 renderas="sect4" id="fast-redirects">
4117 <title>fast-redirects</title>
4121 <term>Typical use:</term>
4123 <para>Fool some click-tracking scripts and speed up indirect links.</para>
4128 <term>Effect:</term>
4131 Detects redirection URLs and redirects the browser without contacting
4132 the redirection server first.
4139 <!-- boolean, parameterized, Multi-value -->
4141 <para>Parameterized.</para>
4146 <term>Parameter:</term>
4151 <quote>simple-check</quote> to just search for the string <quote>http://</quote>
4152 to detect redirection URLs.
4157 <quote>check-decoded-url</quote> to decode URLs (if necessary) before searching
4158 for redirection URLs.
4169 Many sites, like yahoo.com, don't just link to other sites. Instead, they
4170 will link to some script on their own servers, giving the destination as a
4171 parameter, which will then redirect you to the final target. URLs
4172 resulting from this scheme typically look like:
4173 <quote>http://www.example.org/click-tracker.cgi?target=http%3a//www.example.net/</quote>.
4176 Sometimes, there are even multiple consecutive redirects encoded in the
4177 URL. These redirections via scripts make your web browsing more traceable,
4178 since the server from which you follow such a link can see where you go
4179 to. Apart from that, valuable bandwidth and time is wasted, while your
4180 browser asks the server for one redirect after the other. Plus, it feeds
4184 This feature is currently not very smart and is scheduled for improvement.
4185 If it is enabled by default, you will have to create some exceptions to
4186 this action. It can lead to failures in several ways:
4189 Not every URLs with other URLs as parameters is evil.
4190 Some sites offer a real service that requires this information to work.
4191 For example a validation service needs to know, which document to validate.
4192 <literal>fast-redirects</literal> assumes that every URL parameter that
4193 looks like another URL is a redirection target, and will always redirect to
4194 the last one. Most of the time the assumption is correct, but if it isn't,
4195 the user gets redirected anyway.
4198 Another failure occurs if the URL contains other parameters after the URL parameter.
4200 <quote>http://www.example.org/?redirect=http%3a//www.example.net/&foo=bar</quote>.
4201 contains the redirection URL <quote>http://www.example.net/</quote>,
4202 followed by another parameter. <literal>fast-redirects</literal> doesn't know that
4203 and will cause a redirect to <quote>http://www.example.net/&foo=bar</quote>.
4204 Depending on the target server configuration, the parameter will be silently ignored
4205 or lead to a <quote>page not found</quote> error. You can prevent this problem by
4206 first using the <literal><link linkend="redirect">redirect</link></literal> action
4207 to remove the last part of the URL, but it requires a little effort.
4210 To detect a redirection URL, <literal>fast-redirects</literal> only
4211 looks for the string <quote>http://</quote>, either in plain text
4212 (invalid but often used) or encoded as <quote>http%3a//</quote>.
4213 Some sites use their own URL encoding scheme, encrypt the address
4214 of the target server or replace it with a database id. In these cases
4215 <literal>fast-redirects</literal> is fooled and the request reaches the
4216 redirection server where it probably gets logged.
4222 <term>Example usage:</term>
4225 { +fast-redirects{simple-check} }
4228 { +fast-redirects{check-decoded-url} }
4229 another.example.com/testing
4238 <!-- ~~~~~ New section ~~~~~ -->
4239 <sect3 renderas="sect4" id="filter">
4240 <title>filter</title>
4244 <term>Typical use:</term>
4246 <para>Get rid of HTML and JavaScript annoyances, banner advertisements (by size),
4247 do fun text replacements, add personalized effects, etc.</para>
4252 <term>Effect:</term>
4255 All instances of text-based type, most notably HTML and JavaScript, to which
4256 this action applies, can be filtered on-the-fly through the specified regular
4257 expression based substitutions. (Note: as of version 3.0.3 plain text documents
4258 are exempted from filtering, because web servers often use the
4259 <literal>text/plain</literal> MIME type for all files whose type they don't know.)
4266 <!-- boolean, parameterized, Multi-value -->
4268 <para>Multi-value.</para>
4273 <term>Parameter:</term>
4276 The name of a content filter, as defined in the <link linkend="filter-file">filter file</link>.
4277 Filters can be defined in one or more files as defined by the
4278 <literal><link linkend="filterfile">filterfile</link></literal>
4279 option in the <link linkend="config">config file</link>.
4280 <filename>default.filter</filename> is the collection of filters
4281 supplied by the developers. Locally defined filters should go
4282 in their own file, such as <filename>user.filter</filename>.
4285 When used in its negative form,
4286 and without parameters, <emphasis>all</emphasis> filtering is completely disabled.
4295 For your convenience, there are a number of pre-defined filters available
4296 in the distribution filter file that you can use. See the examples below for
4300 Filtering requires buffering the page content, which may appear to
4301 slow down page rendering since nothing is displayed until all content has
4302 passed the filters. (The total time until the page is completely rendered
4303 doesn't change much, but it may be perceived as slower since the page is
4304 not incrementally displayed.)
4305 This effect will be more noticeable on slower connections.
4308 <quote>Rolling your own</quote>
4309 filters requires a knowledge of
4310 <ulink url="https://en.wikipedia.org/wiki/Regular_expressions"><quote>Regular
4311 Expressions</quote></ulink> and
4312 <ulink url="https://en.wikipedia.org/wiki/Html"><quote>HTML</quote></ulink>.
4313 This is very powerful feature, and potentially very intrusive.
4314 Filters should be used with caution, and where an equivalent
4315 <quote>action</quote> is not available.
4318 The amount of data that can be filtered is limited by the
4319 <literal><link linkend="buffer-limit">buffer-limit</link></literal>
4320 option in the main <link linkend="config">config file</link>. The
4321 default is 4096 KB (4 Megs). Once this limit is exceeded, the buffered
4322 data, and all pending data, is passed through unfiltered.
4325 Inappropriate MIME types, such as zipped files, are not filtered at all.
4326 (Again, only text-based types except plain text). Encrypted SSL data
4327 (from HTTPS servers) cannot be filtered either, since this would violate
4328 the integrity of the secure transaction. In some situations it might
4329 be necessary to protect certain text, like source code, from filtering
4330 by defining appropriate <literal>-filter</literal> exceptions.
4333 Compressed content can't be filtered either, but if &my-app;
4334 is compiled with zlib support and a supported compression algorithm
4335 is used (gzip or deflate), &my-app; can first decompress the content
4339 If you use a &my-app; version without zlib support, but want filtering to work on
4340 as much documents as possible, even those that would normally be sent compressed,
4341 you must use the <literal><link linkend="prevent-compression">prevent-compression</link></literal>
4342 action in conjunction with <literal>filter</literal>.
4345 Content filtering can achieve some of the same effects as the
4346 <literal><link linkend="block">block</link></literal>
4347 action, i.e. it can be used to block ads and banners. But the mechanism
4348 works quite differently. One effective use, is to block ad banners
4349 based on their size (see below), since many of these seem to be somewhat
4353 <link linkend="contact">Feedback</link> with suggestions for new or
4354 improved filters is particularly welcome!
4357 The below list has only the names and a one-line description of each
4358 predefined filter. There are <link linkend="predefined-filters">more
4359 verbose explanations</link> of what these filters do in the <link
4360 linkend="filter-file">filter file chapter</link>.
4366 <term>Example usage (with filters from the distribution <filename>default.filter</filename> file).
4367 See <link linkend="PREDEFINED-FILTERS">the Predefined Filters section</link> for
4368 more explanation on each:</term>
4371 <anchor id="filter-js-annoyances">
4373 <screen>+filter{js-annoyances} # Get rid of particularly annoying JavaScript abuse.</screen>
4375 <anchor id="filter-js-events">
4377 <screen>+filter{js-events} # Kill JavaScript event bindings and timers (Radically destructive! Only for extra nasty sites).</screen>
4379 <anchor id="filter-html-annoyances">
4381 <screen>+filter{html-annoyances} # Get rid of particularly annoying HTML abuse.</screen>
4383 <anchor id="filter-content-cookies">
4385 <screen>+filter{content-cookies} # Kill cookies that come in the HTML or JS content.</screen>
4387 <anchor id="filter-refresh-tags">
4389 <screen>+filter{refresh-tags} # Kill automatic refresh tags if refresh time is larger than 9 seconds.</screen>
4391 <anchor id="filter-unsolicited-popups">
4393 <screen>+filter{unsolicited-popups} # Disable only unsolicited pop-up windows.</screen>
4395 <anchor id="filter-all-popups">
4397 <screen>+filter{all-popups} # Kill all popups in JavaScript and HTML.</screen>
4399 <anchor id="filter-img-reorder">
4401 <screen>+filter{img-reorder} # Reorder attributes in <img> tags to make the banners-by-* filters more effective.</screen>
4403 <anchor id="filter-banners-by-size">
4405 <screen>+filter{banners-by-size} # Kill banners by size.</screen>
4407 <anchor id="filter-banners-by-link">
4409 <screen>+filter{banners-by-link} # Kill banners by their links to known clicktrackers.</screen>
4411 <anchor id="filter-webbugs">
4413 <screen>+filter{webbugs} # Squish WebBugs (1x1 invisible GIFs used for user tracking).</screen>
4415 <anchor id="filter-tiny-textforms">
4417 <screen>+filter{tiny-textforms} # Extend those tiny textareas up to 40x80 and kill the hard wrap.</screen>
4419 <anchor id="filter-jumping-windows">
4421 <screen>+filter{jumping-windows} # Prevent windows from resizing and moving themselves.</screen>
4423 <anchor id="filter-frameset-borders">
4425 <screen>+filter{frameset-borders} # Give frames a border and make them resizable.</screen>
4427 <anchor id="filter-iframes">
4429 <screen>+filter{iframes} # Removes all detected iframes. Should only be enabled for individual sites.</screen>
4431 <anchor id="filter-demoronizer">
4433 <screen>+filter{demoronizer} # Fix MS's non-standard use of standard charsets.</screen>
4435 <anchor id="filter-shockwave-flash">
4437 <screen>+filter{shockwave-flash} # Kill embedded Shockwave Flash objects.</screen>
4439 <anchor id="filter-quicktime-kioskmode">
4441 <screen>+filter{quicktime-kioskmode} # Make Quicktime movies saveable.</screen>
4443 <anchor id="filter-fun">
4445 <screen>+filter{fun} # Text replacements for subversive browsing fun!</screen>
4447 <anchor id="filter-crude-parental">
4449 <screen>+filter{crude-parental} # Crude parental filtering. Note that this filter doesn't work reliably.</screen>
4451 <anchor id="filter-ie-exploits">
4453 <screen>+filter{ie-exploits} # Disable some known Internet Explorer bug exploits.</screen>
4455 <anchor id="filter-site-specifics">
4457 <screen>+filter{site-specifics} # Cure for site-specific problems. Don't apply generally!</screen>
4459 <anchor id="filter-no-ping">
4461 <screen>+filter{no-ping} # Removes non-standard ping attributes in <a> and <area> tags.</screen>
4463 <anchor id="filter-bundeswehr.de">
4465 <screen>+filter{bundeswehr.de} # Hide the cookie and privacy info banner on bundeswehr.de.</screen>
4467 <anchor id="filter-github">
4469 <screen>+filter{github} # Removes the annoying "Sign-Up" banner and the Cookie disclaimer.</screen>
4471 <anchor id="filter-google">
4473 <screen>+filter{google} # CSS-based block for Google text ads. Also removes a width limitation and the toolbar advertisement.</screen>
4475 <anchor id="filter-imdb">
4477 <screen>+filter{imdb} # Removes some ads on IMDb.</screen>
4479 <anchor id="filter-yahoo">
4481 <screen>+filter{yahoo} # CSS-based block for Yahoo text ads. Also removes a width limitation.</screen>
4483 <anchor id="filter-msn">
4485 <screen>+filter{msn} # CSS-based block for MSN text ads. Also removes tracking URLs and a width limitation.</screen>
4487 <anchor id="filter-blogspot">
4489 <screen>+filter{blogspot} # Cleans up some Blogspot blogs. Read the fine print before using this.</screen>
4491 <anchor id="filter-sourceforge">
4493 <screen>+filter{sourceforge} # Reduces the amount of ads for proprietary software on SourceForge.</screen>
4500 <!-- ~~~~~ New section ~~~~~ -->
4501 <sect3 renderas="sect4" id="force-text-mode">
4502 <title>force-text-mode</title>
4508 <term>Typical use:</term>
4510 <para>Force <application>Privoxy</application> to treat a document as if it was in some kind of <emphasis>text</emphasis> format. </para>
4515 <term>Effect:</term>
4518 Declares a document as text, even if the <quote>Content-Type:</quote> isn't detected as such.
4525 <!-- Boolean, Parameterized, Multi-value -->
4527 <para>Boolean.</para>
4532 <term>Parameter:</term>
4544 As explained <literal><link linkend="filter">above</link></literal>,
4545 <application>Privoxy</application> tries to only filter files that are
4546 in some kind of text format. The same restrictions apply to
4547 <literal><link linkend="content-type-overwrite">content-type-overwrite</link></literal>.
4548 <literal>force-text-mode</literal> declares a document as text,
4549 without looking at the <quote>Content-Type:</quote> first.
4553 Think twice before activating this action. Filtering binary data
4554 with regular expressions can cause file damage.
4561 <term>Example usage:</term>
4572 <!-- ~~~~~ New section ~~~~~ -->
4573 <sect3 renderas="sect4" id="forward-override">
4574 <title>forward-override</title>
4580 <term>Typical use:</term>
4582 <para>Change the forwarding settings based on User-Agent or request origin</para>
4587 <term>Effect:</term>
4590 Overrules the forward directives in the configuration file.
4597 <!-- Boolean, Parameterized, Multi-value -->
4599 <para>Parameterized.</para>
4604 <term>Parameter:</term>
4608 <para><quote>forward .</quote> to use a direct connection without any additional proxies.</para>
4612 <quote>forward 127.0.0.1:8123</quote> to use the HTTP proxy listening at 127.0.0.1 port 8123.
4617 <quote>forward-socks4a 127.0.0.1:9050 .</quote> to use the socks4a proxy listening at
4618 127.0.0.1 port 9050. Replace <quote>forward-socks4a</quote> with <quote>forward-socks4</quote>
4619 to use a socks4 connection (with local DNS resolution) instead, use <quote>forward-socks5</quote>
4620 for socks5 connections (with remote DNS resolution).
4625 <quote>forward-socks4a 127.0.0.1:9050 proxy.example.org:8000</quote> to use the socks4a proxy
4626 listening at 127.0.0.1 port 9050 to reach the HTTP proxy listening at proxy.example.org port 8000.
4627 Replace <quote>forward-socks4a</quote> with <quote>forward-socks4</quote> to use a socks4 connection
4628 (with local DNS resolution) instead, use <quote>forward-socks5</quote>
4629 for socks5 connections (with remote DNS resolution).
4634 <quote>forward-webserver 127.0.0.1:80</quote> to use the HTTP
4635 server listening at 127.0.0.1 port 80 without adjusting the
4639 This makes it more convenient to use Privoxy to make
4640 existing websites available as onion services as well.
4643 Many websites serve content with hardcoded URLs and
4644 can't be easily adjusted to change the domain based
4645 on the one used by the client.
4648 Putting Privoxy between Tor and the webserver (or an stunnel
4649 that forwards to the webserver) allows to rewrite headers and
4650 content to make client and server happy at the same time.
4653 Using Privoxy for webservers that are only reachable through
4654 onion addresses and whose location is supposed to be secret
4655 is not recommended and should not be necessary anyway.
4666 This action takes parameters similar to the
4667 <link linkend="forwarding">forward</link> directives in the configuration
4668 file, but without the URL pattern. It can be used as replacement, but normally it's only
4669 used in cases where matching based on the request URL isn't sufficient.
4673 Please read the description for the <link linkend="forwarding">forward</link> directives before
4674 using this action. Forwarding to the wrong people will reduce your privacy and increase the
4675 chances of man-in-the-middle attacks.
4678 If the ports are missing or invalid, default values will be used. This might change
4679 in the future and you shouldn't rely on it. Otherwise incorrect syntax causes Privoxy
4680 to exit. Due to design limitations, invalid parameter syntax isn't detected until the
4681 action is used the first time.
4684 Use the <ulink url="http://config.privoxy.org/show-url-info">show-url-info CGI page</ulink>
4685 to verify that your forward settings do what you thought the do.
4692 <term>Example usage:</term>
4695 # Use an ssh tunnel for requests previously tagged as
4696 # <quote>User-Agent: fetch libfetch/2.0</quote> and make sure
4697 # resuming downloads continues to work.
4699 # This way you can continue to use Tor for your normal browsing,
4700 # without overloading the Tor network with your FreeBSD ports updates
4701 # or downloads of bigger files like ISOs.
4703 # Note that HTTP headers are easy to fake and therefore their
4704 # values are as (un)trustworthy as your clients and users.
4705 {+forward-override{forward-socks5 10.0.0.2:2222 .} \
4706 -hide-if-modified-since \
4707 -overwrite-last-modified \
4709 TAG:^User-Agent: fetch libfetch/2\.0$
4717 <!-- ~~~~~ New section ~~~~~ -->
4718 <sect3 renderas="sect4" id="handle-as-empty-document">
4719 <title>handle-as-empty-document</title>
4725 <term>Typical use:</term>
4727 <para>Mark URLs that should be replaced by empty documents <emphasis>if they get blocked</emphasis></para>
4732 <term>Effect:</term>
4735 This action alone doesn't do anything noticeable. It just marks URLs.
4736 If the <literal><link linkend="block">block</link></literal> action <emphasis>also applies</emphasis>,
4737 the presence or absence of this mark decides whether an HTML <quote>BLOCKED</quote>
4738 page, or an empty document will be sent to the client as a substitute for the blocked content.
4739 The <emphasis>empty</emphasis> document isn't literally empty, but actually contains a single space.
4746 <!-- Boolean, Parameterized, Multi-value -->
4748 <para>Boolean.</para>
4753 <term>Parameter:</term>
4765 Some browsers complain about syntax errors if JavaScript documents
4766 are blocked with <application>Privoxy's</application>
4767 default HTML page; this option can be used to silence them.
4768 And of course this action can also be used to eliminate the &my-app;
4769 BLOCKED message in frames.
4772 The content type for the empty document can be specified with
4773 <literal><link linkend="content-type-overwrite">content-type-overwrite{}</link></literal>,
4774 but usually this isn't necessary.
4780 <term>Example usage:</term>
4782 <screen># Block all documents on example.org that end with ".js",
4783 # but send an empty document instead of the usual HTML message.
4784 {+block{Blocked JavaScript} +handle-as-empty-document}
4793 <!-- ~~~~~ New section ~~~~~ -->
4794 <sect3 renderas="sect4" id="handle-as-image">
4795 <title>handle-as-image</title>
4799 <term>Typical use:</term>
4801 <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>
4806 <term>Effect:</term>
4809 This action alone doesn't do anything noticeable. It just marks URLs as images.
4810 If the <literal><link linkend="block">block</link></literal> action <emphasis>also applies</emphasis>,
4811 the presence or absence of this mark decides whether an HTML <quote>blocked</quote>
4812 page, or a replacement image (as determined by the <literal><link
4813 linkend="set-image-blocker">set-image-blocker</link></literal> action) will be sent to the
4814 client as a substitute for the blocked content.
4821 <!-- Boolean, Parameterized, Multi-value -->
4823 <para>Boolean.</para>
4828 <term>Parameter:</term>
4840 The below generic example section is actually part of <filename>default.action</filename>.
4841 It marks all URLs with well-known image file name extensions as images and should
4845 Users will probably only want to use the handle-as-image action in conjunction with
4846 <literal><link linkend="block">block</link></literal>, to block sources of banners, whose URLs don't
4847 reflect the file type, like in the second example section.
4850 Note that you cannot treat HTML pages as images in most cases. For instance, (in-line) ad
4851 frames require an HTML page to be sent, or they won't display properly.
4852 Forcing <literal>handle-as-image</literal> in this situation will not replace the
4853 ad frame with an image, but lead to error messages.
4859 <term>Example usage (sections):</term>
4861 <screen># Generic image extensions:
4864 /.*\.(gif|jpg|jpeg|png|bmp|ico)$
4866 # These don't look like images, but they're banners and should be
4867 # blocked as images:
4869 {+block{Nasty banners.} +handle-as-image}
4870 nasty-banner-server.example.com/junk.cgi\?output=trash
4878 <!-- ~~~~~ New section ~~~~~ -->
4879 <sect3 renderas="sect4" id="hide-accept-language">
4880 <title>hide-accept-language</title>
4886 <term>Typical use:</term>
4888 <para>Pretend to use different language settings.</para>
4893 <term>Effect:</term>
4896 Deletes or replaces the <quote>Accept-Language:</quote> HTTP header in client requests.
4903 <!-- Boolean, Parameterized, Multi-value -->
4905 <para>Parameterized.</para>
4910 <term>Parameter:</term>
4913 Keyword: <quote>block</quote>, or any user defined value.
4922 Faking the browser's language settings can be useful to make a
4923 foreign User-Agent set with
4924 <literal><link linkend="hide-user-agent">hide-user-agent</link></literal>
4928 However some sites with content in different languages check the
4929 <quote>Accept-Language:</quote> to decide which one to take by default.
4930 Sometimes it isn't possible to later switch to another language without
4931 changing the <quote>Accept-Language:</quote> header first.
4934 Therefore it's a good idea to either only change the
4935 <quote>Accept-Language:</quote> header to languages you understand,
4936 or to languages that aren't wide spread.
4939 Before setting the <quote>Accept-Language:</quote> header
4940 to a rare language, you should consider that it helps to
4941 make your requests unique and thus easier to trace.
4942 If you don't plan to change this header frequently,
4943 you should stick to a common language.
4949 <term>Example usage (section):</term>
4951 <screen># Pretend to use Canadian language settings.
4952 {+hide-accept-language{en-ca} \
4953 +hide-user-agent{Mozilla/5.0 (X11; U; OpenBSD i386; en-CA; rv:1.8.0.4) Gecko/20060628 Firefox/1.5.0.4} \
4963 <!-- ~~~~~ New section ~~~~~ -->
4964 <sect3 renderas="sect4" id="hide-content-disposition">
4965 <title>hide-content-disposition</title>
4971 <term>Typical use:</term>
4973 <para>Prevent download menus for content you prefer to view inside the browser.</para>
4978 <term>Effect:</term>
4981 Deletes or replaces the <quote>Content-Disposition:</quote> HTTP header set by some servers.
4988 <!-- Boolean, Parameterized, Multi-value -->
4990 <para>Parameterized.</para>
4995 <term>Parameter:</term>
4998 Keyword: <quote>block</quote>, or any user defined value.
5007 Some servers set the <quote>Content-Disposition:</quote> HTTP header for
5008 documents they assume you want to save locally before viewing them.
5009 The <quote>Content-Disposition:</quote> header contains the file name
5010 the browser is supposed to use by default.
5013 In most browsers that understand this header, it makes it impossible to
5014 <emphasis>just view</emphasis> the document, without downloading it first,
5015 even if it's just a simple text file or an image.
5018 Removing the <quote>Content-Disposition:</quote> header helps
5019 to prevent this annoyance, but some browsers additionally check the
5020 <quote>Content-Type:</quote> header, before they decide if they can
5021 display a document without saving it first. In these cases, you have
5022 to change this header as well, before the browser stops displaying
5026 It is also possible to change the server's file name suggestion
5027 to another one, but in most cases it isn't worth the time to set
5031 This action will probably be removed in the future,
5032 use server-header filters instead.
5038 <term>Example usage:</term>
5041 # Disarm the download link in Sourceforge's patch tracker
5043 +content-type-overwrite{text/plain} \
5044 +hide-content-disposition{block} \
5046 .sourceforge.net/tracker/download\.php
5054 <!-- ~~~~~ New section ~~~~~ -->
5055 <sect3 renderas="sect4" id="hide-if-modified-since">
5056 <title>hide-if-modified-since</title>
5062 <term>Typical use:</term>
5064 <para>Prevent yet another way to track the user's steps between sessions.</para>
5069 <term>Effect:</term>
5072 Deletes the <quote>If-Modified-Since:</quote> HTTP client header or modifies its value.
5079 <!-- Boolean, Parameterized, Multi-value -->
5081 <para>Parameterized.</para>
5086 <term>Parameter:</term>
5089 Keyword: <quote>block</quote>, or a user defined value that specifies a range of hours.
5098 Removing this header is useful for filter testing, where you want to force a real
5099 reload instead of getting status code <quote>304</quote>, which would cause the
5100 browser to use a cached copy of the page.
5103 Instead of removing the header, <literal>hide-if-modified-since</literal> can
5104 also add or subtract a random amount of time to/from the header's value.
5105 You specify a range of minutes where the random factor should be chosen from and
5106 <application>Privoxy</application> does the rest. A negative value means
5107 subtracting, a positive value adding.
5110 Randomizing the value of the <quote>If-Modified-Since:</quote> makes
5111 it less likely that the server can use the time as a cookie replacement,
5112 but you will run into caching problems if the random range is too high.
5115 It is a good idea to only use a small negative value and let
5116 <literal><link linkend="overwrite-last-modified">overwrite-last-modified</link></literal>
5117 handle the greater changes.
5120 It is also recommended to use this action together with
5121 <literal><link linkend="crunch-if-none-match">crunch-if-none-match</link></literal>,
5122 otherwise it's more or less pointless.
5128 <term>Example usage (section):</term>
5130 <screen># Let the browser revalidate but make tracking based on the time less likely.
5131 {+hide-if-modified-since{-60} \
5132 +overwrite-last-modified{randomize} \
5133 +crunch-if-none-match}
5141 <!-- ~~~~~ New section ~~~~~ -->
5142 <sect3 renderas="sect4" id="hide-from-header">
5143 <title>hide-from-header</title>
5147 <term>Typical use:</term>
5149 <para>Keep your (old and ill) browser from telling web servers your email address</para>
5154 <term>Effect:</term>
5157 Deletes any existing <quote>From:</quote> HTTP header, or replaces it with the
5165 <!-- Boolean, Parameterized, Multi-value -->
5167 <para>Parameterized.</para>
5172 <term>Parameter:</term>
5175 Keyword: <quote>block</quote>, or any user defined value.
5184 The keyword <quote>block</quote> will completely remove the header
5185 (not to be confused with the <literal><link linkend="block">block</link></literal>
5189 Alternately, you can specify any value you prefer to be sent to the web
5190 server. If you do, it is a matter of fairness not to use any address that
5191 is actually used by a real person.
5194 This action is rarely needed, as modern web browsers don't send
5195 <quote>From:</quote> headers anymore.
5201 <term>Example usage:</term>
5203 <screen>+hide-from-header{block}</screen>
5205 <screen>+hide-from-header{spam-me-senseless@sittingduck.example.com}</screen>
5212 <!-- ~~~~~ New section ~~~~~ -->
5213 <sect3 renderas="sect4" id="hide-referrer">
5214 <title>hide-referrer</title>
5215 <anchor id="hide-referer">
5218 <term>Typical use:</term>
5220 <para>Conceal which link you followed to get to a particular site</para>
5225 <term>Effect:</term>
5228 Deletes the <quote>Referer:</quote> (sic) HTTP header from the client request,
5229 or replaces it with a forged one.
5236 <!-- Boolean, Parameterized, Multi-value -->
5238 <para>Parameterized.</para>
5243 <term>Parameter:</term>
5247 <para><quote>conditional-block</quote> to delete the header completely if the host has changed.</para>
5250 <para><quote>conditional-forge</quote> to forge the header if the host has changed.</para>
5253 <para><quote>block</quote> to delete the header unconditionally.</para>
5256 <para><quote>forge</quote> to pretend to be coming from the homepage of the server we are talking to.</para>
5259 <para>Any other string to set a user defined referrer.</para>
5269 <literal>conditional-block</literal> is the only parameter,
5270 that isn't easily detected in the server's log file. If it blocks the
5271 referrer, the request will look like the visitor used a bookmark or
5272 typed in the address directly.
5275 Leaving the referrer unmodified for requests on the same host
5276 allows the server owner to see the visitor's <quote>click path</quote>,
5277 but in most cases she could also get that information by comparing
5278 other parts of the log file: for example the User-Agent if it isn't
5279 a very common one, or the user's IP address if it doesn't change between
5283 Always blocking the referrer, or using a custom one, can lead to
5284 failures on servers that check the referrer before they answer any
5285 requests, in an attempt to prevent their content from being
5286 embedded or linked to elsewhere.
5289 Both <literal>conditional-block</literal> and <literal>forge</literal>
5290 will work with referrer checks, as long as content and valid referring page
5291 are on the same host. Most of the time that's the case.
5294 <literal>hide-referer</literal> is an alternate spelling of
5295 <literal>hide-referrer</literal> and the two can be can be freely
5296 substituted with each other. (<quote>referrer</quote> is the
5297 correct English spelling, however the HTTP specification has a bug - it
5298 requires it to be spelled as <quote>referer</quote>.)
5304 <term>Example usage:</term>
5306 <screen>+hide-referrer{forge}</screen>
5308 <screen>+hide-referrer{http://www.yahoo.com/}</screen>
5315 <!-- ~~~~~ New section ~~~~~ -->
5316 <sect3 renderas="sect4" id="hide-user-agent">
5317 <title>hide-user-agent</title>
5321 <term>Typical use:</term>
5323 <para>Try to conceal your type of browser and client operating system</para>
5328 <term>Effect:</term>
5331 Replaces the value of the <quote>User-Agent:</quote> HTTP header
5332 in client requests with the specified value.
5339 <!-- Boolean, Parameterized, Multi-value -->
5341 <para>Parameterized.</para>
5346 <term>Parameter:</term>
5349 Any user-defined string.
5359 This can lead to problems on web sites that depend on looking at this header in
5360 order to customize their content for different browsers (which, by the
5361 way, is <emphasis>NOT</emphasis> the right thing to do: good web sites
5362 work browser-independently).
5366 Using this action in multi-user setups or wherever different types of
5367 browsers will access the same <application>Privoxy</application> is
5368 <emphasis>not recommended</emphasis>. In single-user, single-browser
5369 setups, you might use it to delete your OS version information from
5370 the headers, because it is an invitation to exploit known bugs for your
5371 OS. It is also occasionally useful to forge this in order to access
5372 sites that won't let you in otherwise (though there may be a good
5373 reason in some cases).
5376 More information on known user-agent strings can be found at
5377 <ulink url="http://www.user-agents.org/">http://www.user-agents.org/</ulink>
5379 <ulink url="https://en.wikipedia.org/wiki/User_agent">http://en.wikipedia.org/wiki/User_agent</ulink>.
5385 <term>Example usage:</term>
5387 <screen>+hide-user-agent{Mozilla/5.0 (X11; ElectroBSD i386; rv:78.0) Gecko/20100101 Firefox/78.0}</screen>
5394 <!-- ~~~~~ New section ~~~~~ -->
5395 <sect3 renderas="sect4" id="https-inspection">
5396 <title>https-inspection</title>
5400 <term>Typical use:</term>
5402 <para>Filter encrypted requests and responses</para>
5407 <term>Effect:</term>
5410 Encrypted requests are decrypted, filtered and forwarded encrypted.
5417 <!-- boolean, parameterized, Multi-value -->
5419 <para>Boolean.</para>
5424 <term>Parameter:</term>
5436 This action allows &my-app; to filter encrypted requests and responses.
5437 For this to work &my-app; has to generate a certificate for the web site
5438 and send it to the client which has to accept it.
5441 Before this works the directives in the
5442 <literal><ulink url="config.html#HTTPS-INSPECTION-DIRECTIVES">HTTPS inspection section</ulink></literal>
5443 of the config file have to be configured.
5446 Note that the action has to be enabled based on the CONNECT
5447 request which doesn't contain a path. Enabling it based on
5448 a pattern with path doesn't work as the path is only seen
5449 by &my-app; if the action is already enabled.
5455 <term>Example usage (section):</term>
5457 <screen>{+https-inspection}
5458 www.example.com</screen>
5466 <!-- ~~~~~ New section ~~~~~ -->
5467 <sect3 renderas="sect4" id="ignore-certificate-errors">
5468 <title>ignore-certificate-errors</title>
5472 <term>Typical use:</term>
5474 <para>Filter encrypted requests and responses without verifying the certificate</para>
5479 <term>Effect:</term>
5482 Encrypted requests are forwarded to sites without verifying the certificate.
5489 <!-- Boolean, Parameterized, Multi-value -->
5491 <para>Boolean.</para>
5496 <term>Parameter:</term>
5509 <link linkend="HTTPS-INSPECTION"><quote>+https-inspection</quote></link>
5510 action is used &my-app; by default verifies that the remote site uses a valid
5514 If the certificate can't be validated by &my-app; the connection is aborted.
5517 This action disables the certificate check so requests to sites
5518 with certificates that can't be validated are allowed.
5521 Note that enabling this action allows Man-in-the-middle attacks.
5527 <term>Example usage:</term>
5530 {+ignore-certificate-errors}
5539 <!-- ~~~~~ New section ~~~~~ -->
5540 <sect3 renderas="sect4" id="limit-connect">
5541 <title>limit-connect</title>
5545 <term>Typical use:</term>
5547 <para>Prevent abuse of <application>Privoxy</application> as a TCP proxy relay or disable SSL for untrusted sites</para>
5552 <term>Effect:</term>
5555 Specifies to which ports HTTP CONNECT requests are allowable.
5562 <!-- Boolean, Parameterized, Multi-value -->
5564 <para>Parameterized.</para>
5569 <term>Parameter:</term>
5572 A comma-separated list of ports or port ranges (the latter using dashes, with the minimum
5573 defaulting to 0 and the maximum to 65K).
5582 By default, i.e. if no <literal>limit-connect</literal> action applies,
5583 <application>Privoxy</application> allows HTTP CONNECT requests to all
5584 ports. Use <literal>limit-connect</literal> if fine-grained control
5585 is desired for some or all destinations.
5588 The CONNECT methods exists in HTTP to allow access to secure websites
5589 (<quote>https://</quote> URLs) through proxies. It works very simply:
5590 the proxy connects to the server on the specified port, and then
5591 short-circuits its connections to the client and to the remote server.
5592 This means CONNECT-enabled proxies can be used as TCP relays very easily.
5595 <application>Privoxy</application> relays HTTPS traffic without seeing
5596 the decoded content. Websites can leverage this limitation to circumvent &my-app;'s
5597 filters. By specifying an invalid port range you can disable HTTPS entirely.
5603 <term>Example usages:</term>
5605 <!-- I had trouble getting the spacing to look right in my browser -->
5606 <!-- I probably have the wrong font setup, bollocks. -->
5607 <!-- Apparently the emphasis tag uses a proportional font no matter what -->
5608 <screen>+limit-connect{443} # Port 443 is OK.
5609 +limit-connect{80,443} # Ports 80 and 443 are OK.
5610 +limit-connect{-3, 7, 20-100, 500-} # Ports less than 3, 7, 20 to 100 and above 500 are OK.
5611 +limit-connect{-} # All ports are OK
5612 +limit-connect{,} # No HTTPS/SSL traffic is allowed</screen>
5619 <!-- ~~~~~ New section ~~~~~ -->
5620 <sect3 renderas="sect4" id="limit-cookie-lifetime">
5621 <title>limit-cookie-lifetime</title>
5625 <term>Typical use:</term>
5627 <para>Limit the lifetime of HTTP cookies to a couple of minutes or hours.</para>
5632 <term>Effect:</term>
5635 Overwrites the expires field in Set-Cookie server headers if it's above the specified limit.
5642 <!-- Boolean, Parameterized, Multi-value -->
5644 <para>Parameterized.</para>
5649 <term>Parameter:</term>
5652 The lifetime limit in minutes, or 0.
5661 This action reduces the lifetime of HTTP cookies coming from the
5662 server to the specified number of minutes, starting from the time
5663 the cookie passes Privoxy.
5666 Cookies with a lifetime below the limit are not modified.
5667 The lifetime of session cookies is set to the specified limit.
5670 The effect of this action depends on the server.
5673 In case of servers which refresh their cookies with each response
5674 (or at least frequently), the lifetime limit set by this action
5676 Thus, a session associated with the cookie continues to work with
5677 this action enabled, as long as a new request is made before the
5678 last limit set is reached.
5681 However, some servers send their cookies once, with a lifetime of several
5682 years (the year 2037 is a popular choice), and do not refresh them
5683 until a certain event in the future, for example the user logging out.
5684 In this case this action may limit the absolute lifetime of the session,
5685 even if requests are made frequently.
5688 If the parameter is <quote>0</quote>, this action behaves like
5689 <literal><link linkend="session-cookies-only">session-cookies-only</link></literal>.
5695 <term>Example usages:</term>
5697 <screen>+limit-cookie-lifetime{60}</screen>
5703 <!-- ~~~~~ New section ~~~~~ -->
5704 <sect3 renderas="sect4" id="prevent-compression">
5705 <title>prevent-compression</title>
5709 <term>Typical use:</term>
5712 Ensure that servers send the content uncompressed, so it can be
5713 passed through <literal><link linkend="filter">filter</link></literal>s.
5719 <term>Effect:</term>
5722 Removes the Accept-Encoding header which can be used to ask for compressed transfer.
5729 <!-- Boolean, Parameterized, Multi-value -->
5731 <para>Boolean.</para>
5736 <term>Parameter:</term>
5748 More and more websites send their content compressed by default, which
5749 is generally a good idea and saves bandwidth. But the <literal><link
5750 linkend="filter">filter</link></literal> and
5751 <literal><link linkend="deanimate-gifs">deanimate-gifs</link></literal>
5752 actions need access to the uncompressed data.
5755 When compiled with zlib support (available since &my-app; 3.0.7), content that should be
5756 filtered is decompressed on-the-fly and you don't have to worry about this action.
5757 If you are using an older &my-app; version, or one that hasn't been compiled with zlib
5758 support, this action can be used to convince the server to send the content uncompressed.
5761 Most text-based instances compress very well, the size is seldom decreased by less than 50%,
5762 for markup-heavy instances like news feeds saving more than 90% of the original size isn't
5766 Not using compression will therefore slow down the transfer, and you should only
5767 enable this action if you really need it. As of &my-app; 3.0.7 it's disabled in all
5768 predefined action settings.
5771 Note that some (rare) ill-configured sites don't handle requests for uncompressed
5772 documents correctly. Broken PHP applications tend to send an empty document body,
5773 some IIS versions only send the beginning of the content and some content delivery
5774 networks let the connection time out.
5775 If you enable <literal>prevent-compression</literal> per default, you might
5776 want to add exceptions for those sites. See the example for how to do that.
5782 <term>Example usage (sections):</term>
5785 # Selectively turn off compression, and enable a filter
5787 { +filter{tiny-textforms} +prevent-compression }
5788 # Match only these sites
5793 # Or instead, we could set a universal default:
5795 { +prevent-compression }
5798 # Then maybe make exceptions for broken sites:
5800 { -prevent-compression }
5810 <!-- ~~~~~ New section ~~~~~ -->
5811 <sect3 renderas="sect4" id="overwrite-last-modified">
5812 <title>overwrite-last-modified</title>
5818 <term>Typical use:</term>
5820 <para>Prevent yet another way to track the user's steps between sessions.</para>
5825 <term>Effect:</term>
5828 Deletes the <quote>Last-Modified:</quote> HTTP server header or modifies its value.
5835 <!-- Boolean, Parameterized, Multi-value -->
5837 <para>Parameterized.</para>
5842 <term>Parameter:</term>
5845 One of the keywords: <quote>block</quote>, <quote>reset-to-request-time</quote>
5846 and <quote>randomize</quote>
5855 Removing the <quote>Last-Modified:</quote> header is useful for filter
5856 testing, where you want to force a real reload instead of getting status
5857 code <quote>304</quote>, which would cause the browser to reuse the old
5858 version of the page.
5861 The <quote>randomize</quote> option overwrites the value of the
5862 <quote>Last-Modified:</quote> header with a randomly chosen time
5863 between the original value and the current time. In theory the server
5864 could send each document with a different <quote>Last-Modified:</quote>
5865 header to track visits without using cookies. <quote>Randomize</quote>
5866 makes it impossible and the browser can still revalidate cached documents.
5869 <quote>reset-to-request-time</quote> overwrites the value of the
5870 <quote>Last-Modified:</quote> header with the current time. You could use
5871 this option together with
5872 <literal><link linkend="hide-if-modified-since">hide-if-modified-since</link></literal>
5873 to further customize your random range.
5876 The preferred parameter here is <quote>randomize</quote>. It is safe
5877 to use, as long as the time settings are more or less correct.
5878 If the server sets the <quote>Last-Modified:</quote> header to the time
5879 of the request, the random range becomes zero and the value stays the same.
5880 Therefore you should later randomize it a second time with
5881 <literal><link linkend="hide-if-modified-since">hided-if-modified-since</link></literal>,
5885 It is also recommended to use this action together with
5886 <literal><link linkend="crunch-if-none-match">crunch-if-none-match</link></literal>.
5892 <term>Example usage:</term>
5895 # Let the browser revalidate without being tracked across sessions
5896 { +hide-if-modified-since{-60} \
5897 +overwrite-last-modified{randomize} \
5898 +crunch-if-none-match \
5908 <!-- ~~~~~ New section ~~~~~ -->
5909 <sect3 renderas="sect4" id="redirect">
5910 <title>redirect</title>
5916 <term>Typical use:</term>
5919 Redirect requests to other sites.
5925 <term>Effect:</term>
5928 Convinces the browser that the requested document has been moved
5929 to another location and the browser should get it from there.
5936 <!-- Boolean, Parameterized, Multi-value -->
5938 <para>Parameterized</para>
5943 <term>Parameter:</term>
5946 An absolute URL or a single pcrs command.
5955 Requests to which this action applies are answered with a
5956 HTTP redirect to URLs of your choosing. The new URL is
5957 either provided as parameter, or derived by applying a
5958 single pcrs command to the original URL.
5961 The syntax for pcrs commands is documented in the
5962 <link linkend="filter-file">filter file</link> section.
5965 Requests can't be blocked and redirected at the same time,
5966 applying this action together with
5967 <literal><link linkend="block">block</link></literal>
5968 is a configuration error. Currently the request is blocked
5969 and an error message logged, the behavior may change in the
5970 future and result in Privoxy rejecting the action file.
5973 This action can be combined with
5974 <literal><link linkend="fast-redirects">fast-redirects{check-decoded-url}</link></literal>
5975 to redirect to a decoded version of a rewritten URL.
5978 Use this action carefully, make sure not to create redirection loops
5979 and be aware that using your own redirects might make it
5980 possible to fingerprint your requests.
5983 In case of problems with your redirects, or simply to watch
5984 them working, enable <link linkend="DEBUG">debug 128</link>.
5990 <term>Example usages:</term>
5993 # Replace example.com's style sheet with another one
5994 { +redirect{http://localhost/css-replacements/example.com.css} }
5995 example.com/stylesheet\.css
5997 # Create a short, easy to remember nickname for a favorite site
5998 # (relies on the browser to accept and forward invalid URLs to &my-app;)
5999 { +redirect{https://www.privoxy.org/user-manual/actions-file.html} }
6002 # Always use the expanded view for Undeadly.org articles
6003 # (Note the $ at the end of the URL pattern to make sure
6004 # the request for the rewritten URL isn't redirected as well)
6005 {+redirect{s@$@&mode=expanded@}}
6006 undeadly.org/cgi\?action=article&sid=\d*$
6008 # Redirect Google search requests to MSN
6009 {+redirect{s@^http://[^/]*/search\?q=([^&]*).*@http://search.msn.com/results.aspx?q=$1@}}
6012 # Redirect MSN search requests to Yahoo
6013 {+redirect{s@^http://[^/]*/results\.aspx\?q=([^&]*).*@http://search.yahoo.com/search?p=$1@}}
6014 search.msn.com//results\.aspx\?q=
6016 # Redirect http://example.com/&bla=fasel&toChange=foo (and any other value but "bar")
6017 # to http://example.com/&bla=fasel&toChange=bar
6019 # The URL pattern makes sure that the following request isn't redirected again.
6020 {+redirect{s@toChange=[^&]+@toChange=bar@}}
6021 example.com/.*toChange=(?!bar)
6023 # Add a shortcut to look up illumos bugs
6024 {+redirect{s@^http://i([0-9]+)/.*@https://www.illumos.org/issues/$1@}}
6025 # Redirected URL = http://i4974/
6026 # Redirect Destination = https://www.illumos.org/issues/4974
6027 i[0-9][0-9][0-9][0-9]*/
6029 # Redirect requests for the old Tor Hidden Service of the Privoxy website to the new one
6030 {+redirect{s@^http://jvauzb4sb3bwlsnc.onion/@http://l3tczdiiwoo63iwxty4lhs6p7eaxop5micbn7vbliydgv63x5zrrrfyd.onion/@}}
6031 jvauzb4sb3bwlsnc.onion/
6033 # Redirect remote requests for this manual
6034 # to the local version delivered by Privoxy
6035 {+redirect{s@^http://www@http://config@}}
6036 www.privoxy.org/user-manual/</screen>
6044 <!-- ~~~~~ New section ~~~~~ -->
6045 <sect3 renderas="sect4" id="server-header-filter">
6046 <title>server-header-filter</title>
6050 <term>Typical use:</term>
6053 Rewrite or remove single server headers.
6059 <term>Effect:</term>
6062 All server headers to which this action applies are filtered on-the-fly
6063 through the specified regular expression based substitutions.
6070 <!-- boolean, parameterized, Multi-value -->
6072 <para>Multi-value.</para>
6077 <term>Parameter:</term>
6080 The name of a server-header filter, as defined in one of the
6081 <link linkend="filter-file">filter files</link>.
6090 Server-header filters are applied to each header on its own, not to
6091 all at once. This makes it easier to diagnose problems, but on the downside
6092 you can't write filters that only change header x if header y's value is z.
6093 You can do that by using tags though.
6096 Server-header filters are executed after the other header actions have finished
6097 and use their output as input.
6100 Please refer to the <link linkend="filter-file">filter file chapter</link>
6101 to learn which server-header filters are available by default, and how to
6108 <term>Example usage (section):</term>
6111 {+server-header-filter{html-to-xml}}
6112 example.org/xml-instance-that-is-delivered-as-html
6114 {+server-header-filter{xml-to-html}}
6115 example.org/instance-that-is-delivered-as-xml-but-is-not
6124 <!-- ~~~~~ New section ~~~~~ -->
6125 <sect3 renderas="sect4" id="server-header-tagger">
6126 <title>server-header-tagger</title>
6130 <term>Typical use:</term>
6133 Enable or disable filters based on the Content-Type header.
6139 <term>Effect:</term>
6142 Server headers to which this action applies are filtered on-the-fly through
6143 the specified regular expression based substitutions, the result is used as
6151 <!-- boolean, parameterized, Multi-value -->
6153 <para>Multi-value.</para>
6158 <term>Parameter:</term>
6161 The name of a server-header tagger, as defined in one of the
6162 <link linkend="filter-file">filter files</link>.
6171 Server-header taggers are applied to each header on its own,
6172 and as the header isn't modified, each tagger <quote>sees</quote>
6176 Server-header taggers are executed before all other header actions
6177 that modify server headers. Their tags can be used to control
6178 all of the other server-header actions, the content filters
6179 and the crunch actions (<link linkend="redirect">redirect</link>
6180 and <link linkend="block">block</link>).
6183 Obviously crunching based on tags created by server-header taggers
6184 doesn't prevent the request from showing up in the server's log file.
6191 <term>Example usage (section):</term>
6194 # Tag every request with the content type declared by the server
6195 {+server-header-tagger{content-type}}
6198 # If the response has a tag starting with 'image/' enable an external
6199 # filter that only applies to images.
6201 # Note that the filter is not available by default, it's just a
6202 # <literal><link linkend="external-filter-syntax">silly example</link></literal>.
6203 {+external-filter{rotate-image} +force-text-mode}
6213 <!-- ~~~~~ New section ~~~~~ -->
6214 <sect3 renderas="sect4" id="suppress-tag">
6215 <title>suppress-tag</title>
6219 <term>Typical use:</term>
6222 Suppress client or server tag.
6228 <term>Effect:</term>
6231 Server or client tags to which this action applies are not added to the request,
6232 thus making all actions that are specific to these request tags inactive.
6239 <!-- boolean, parameterized, Multi-value -->
6241 <para>Multi-value.</para>
6246 <term>Parameter:</term>
6249 The result tag of a server-header or client-header tagger, as defined in one of the
6250 <link linkend="filter-file">filter files</link>.
6256 <term>Example usage (section):</term>
6259 # Suppress tag produced by range-requests client-header tagger for requests coming from address 10.0.0.1
6260 {+suppress-tag{RANGE-REQUEST}}
6261 TAG:^IP-ADDRESS: 10\.0\.0\.1$
6270 <!-- ~~~~~ New section ~~~~~ -->
6271 <sect3 renderas="sect4" id="session-cookies-only">
6272 <title>session-cookies-only</title>
6276 <term>Typical use:</term>
6279 Allow only temporary <quote>session</quote> cookies (for the current
6280 browser session <emphasis>only</emphasis>).
6286 <term>Effect:</term>
6289 Deletes the <quote>expires</quote> field from <quote>Set-Cookie:</quote>
6290 server headers. Most browsers will not store such cookies permanently and
6291 forget them in between sessions.
6298 <!-- Boolean, Parameterized, Multi-value -->
6300 <para>Boolean.</para>
6305 <term>Parameter:</term>
6317 This is less strict than <literal><link linkend="crunch-incoming-cookies">crunch-incoming-cookies</link></literal> /
6318 <literal><link linkend="crunch-outgoing-cookies">crunch-outgoing-cookies</link></literal> and allows you to browse
6319 websites that insist or rely on setting cookies, without compromising your privacy too badly.
6322 Most browsers will not permanently store cookies that have been processed by
6323 <literal>session-cookies-only</literal> and will forget about them between sessions.
6324 This makes profiling cookies useless, but won't break sites which require cookies so
6325 that you can log in for transactions. This is generally turned on for all
6326 sites, and is the recommended setting.
6329 It makes <emphasis>no sense at all</emphasis> to use <literal>session-cookies-only</literal>
6330 together with <literal><link linkend="crunch-incoming-cookies">crunch-incoming-cookies</link></literal> or
6331 <literal><link linkend="crunch-outgoing-cookies">crunch-outgoing-cookies</link></literal>. If you do, cookies
6332 will be plainly killed.
6335 Note that it is up to the browser how it handles such cookies without an <quote>expires</quote>
6336 field. If you use an exotic browser, you might want to try it out to be sure.
6339 This setting also has no effect on cookies that may have been stored
6340 previously by the browser before starting <application>Privoxy</application>.
6341 These would have to be removed manually.
6344 <application>Privoxy</application> also uses
6345 the <link linkend="filter-content-cookies">content-cookies filter</link>
6346 to block some types of cookies. Content cookies are not effected by
6347 <literal>session-cookies-only</literal>.
6353 <term>Example usage:</term>
6355 <screen>+session-cookies-only</screen>
6362 <!-- ~~~~~ New section ~~~~~ -->
6363 <sect3 renderas="sect4" id="set-image-blocker">
6364 <title>set-image-blocker</title>
6368 <term>Typical use:</term>
6370 <para>Choose the replacement for blocked images</para>
6375 <term>Effect:</term>
6378 This action alone doesn't do anything noticeable. If <emphasis>both</emphasis>
6379 <literal><link linkend="block">block</link></literal> <emphasis>and</emphasis> <literal><link
6380 linkend="handle-as-image">handle-as-image</link></literal> <emphasis>also</emphasis>
6381 apply, i.e. if the request is to be blocked as an image,
6382 <emphasis>then</emphasis> the parameter of this action decides what will be
6383 sent as a replacement.
6390 <!-- Boolean, Parameterized, Multi-value -->
6392 <para>Parameterized.</para>
6397 <term>Parameter:</term>
6402 <quote>pattern</quote> to send a built-in checkerboard pattern image. The image is visually
6403 decent, scales very well, and makes it obvious where banners were busted.
6408 <quote>blank</quote> to send a built-in transparent image. This makes banners disappear
6409 completely, but makes it hard to detect where <application>Privoxy</application> has blocked
6410 images on a given page and complicates troubleshooting if <application>Privoxy</application>
6411 has blocked innocent images, like navigation icons.
6416 <quote><replaceable class="parameter">target-url</replaceable></quote> to
6417 send a redirect to <replaceable class="parameter">target-url</replaceable>. You can redirect
6418 to any image anywhere, even in your local filesystem via <quote>file:///</quote> URL.
6419 (But note that not all browsers support redirecting to a local file system).
6422 A good application of redirects is to use special <application>Privoxy</application>-built-in
6423 URLs, which send the built-in images, as <replaceable class="parameter">target-url</replaceable>.
6424 This has the same visual effect as specifying <quote>blank</quote> or <quote>pattern</quote> in
6425 the first place, but enables your browser to cache the replacement image, instead of requesting
6426 it over and over again.
6437 The URLs for the built-in images are <quote>http://config.privoxy.org/send-banner?type=<replaceable
6438 class="parameter">type</replaceable></quote>, where <replaceable class="parameter">type</replaceable> is
6439 either <quote>blank</quote> or <quote>pattern</quote>.
6442 There is a third (advanced) type, called <quote>auto</quote>. It is <emphasis>NOT</emphasis> to be
6443 used in <literal>set-image-blocker</literal>, but meant for use from <link linkend="filter-file">filters</link>.
6444 Auto will select the type of image that would have applied to the referring page, had it been an image.
6450 <term>Example usage:</term>
6455 <screen>+set-image-blocker{pattern}</screen>
6457 Redirect to the BSD daemon:
6459 <screen>+set-image-blocker{http://www.freebsd.org/gifs/dae_up3.gif}</screen>
6461 Redirect to the built-in pattern for better caching:
6463 <screen>+set-image-blocker{http://config.privoxy.org/send-banner?type=pattern}</screen>
6470 <!-- ~~~~~ New section ~~~~~ -->
6471 <sect3 id="summary">
6472 <title>Summary</title>
6474 Note that many of these actions have the potential to cause a page to
6475 misbehave, possibly even not to display at all. There are many ways
6476 a site designer may choose to design his site, and what HTTP header
6477 content, and other criteria, he may depend on. There is no way to have hard
6478 and fast rules for all sites. See the <link
6479 linkend="ACTIONSANAT">Appendix</link> for a brief example on troubleshooting
6485 <!-- ~~~~~ New section ~~~~~ -->
6486 <sect2 id="aliases">
6487 <title>Aliases</title>
6489 Custom <quote>actions</quote>, known to <application>Privoxy</application>
6490 as <quote>aliases</quote>, can be defined by combining other actions.
6491 These can in turn be invoked just like the built-in actions.
6492 Currently, an alias name can contain any character except space, tab,
6494 <quote>{</quote> and <quote>}</quote>, but we <emphasis>strongly
6495 recommend</emphasis> that you only use <quote>a</quote> to <quote>z</quote>,
6496 <quote>0</quote> to <quote>9</quote>, <quote>+</quote>, and <quote>-</quote>.
6497 Alias names are not case sensitive, and are not required to start with a
6498 <quote>+</quote> or <quote>-</quote> sign, since they are merely textually
6502 Aliases can be used throughout the actions file, but they <emphasis>must be
6503 defined in a special section at the top of the file!</emphasis>
6504 And there can only be one such section per actions file. Each actions file may
6505 have its own alias section, and the aliases defined in it are only visible
6509 There are two main reasons to use aliases: One is to save typing for frequently
6510 used combinations of actions, the other one is a gain in flexibility: If you
6511 decide once how you want to handle shops by defining an alias called
6512 <quote>shop</quote>, you can later change your policy on shops in
6513 <emphasis>one</emphasis> place, and your changes will take effect everywhere
6514 in the actions file where the <quote>shop</quote> alias is used. Calling aliases
6515 by their purpose also makes your actions files more readable.
6518 Currently, there is one big drawback to using aliases, though:
6519 <application>Privoxy</application>'s built-in web-based action file
6520 editor honors aliases when reading the actions files, but it expands
6521 them before writing. So the effects of your aliases are of course preserved,
6522 but the aliases themselves are lost when you edit sections that use aliases
6527 Now let's define some aliases...
6531 # Useful custom aliases we can use later.
6533 # Note the (required!) section header line and that this section
6534 # must be at the top of the actions file!
6538 # These aliases just save typing later:
6539 # (Note that some already use other aliases!)
6541 +crunch-all-cookies = +<link linkend="CRUNCH-INCOMING-COOKIES">crunch-incoming-cookies</link> +<link linkend="CRUNCH-OUTGOING-COOKIES">crunch-outgoing-cookies</link>
6542 -crunch-all-cookies = -<link linkend="CRUNCH-INCOMING-COOKIES">crunch-incoming-cookies</link> -<link linkend="CRUNCH-OUTGOING-COOKIES">crunch-outgoing-cookies</link>
6543 +block-as-image = +block{Blocked image.} +handle-as-image
6544 allow-all-cookies = -crunch-all-cookies -<link linkend="SESSION-COOKIES-ONLY">session-cookies-only</link> -<link linkend="FILTER-CONTENT-COOKIES">filter{content-cookies}</link>
6546 # These aliases define combinations of actions
6547 # that are useful for certain types of sites:
6549 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>
6551 shop = -crunch-all-cookies -<link linkend="FILTER-ALL-POPUPS">filter{all-popups}</link>
6553 # Short names for other aliases, for really lazy people ;-)
6555 c0 = +crunch-all-cookies
6556 c1 = -crunch-all-cookies
6560 ...and put them to use. These sections would appear in the lower part of an
6561 actions file and define exceptions to the default actions (as specified further
6562 up for the <quote>/</quote> pattern):
6566 # These sites are either very complex or very keen on
6567 # user data and require minimal interference to work:
6570 .office.microsoft.com
6571 .windowsupdate.microsoft.com
6572 # Gmail is really mail.google.com, not gmail.com
6576 # Allow cookies (for setting and retrieving your customer data)
6580 .worldpay.com # for quietpc.com
6583 # These shops require pop-ups:
6585 {-filter{all-popups} -filter{unsolicited-popups}}
6591 Aliases like <quote>shop</quote> and <quote>fragile</quote> are typically used for
6592 <quote>problem</quote> sites that require more than one action to be disabled
6593 in order to function properly.
6599 <!-- ~~~~~ New section ~~~~~ -->
6600 <sect2 id="act-examples">
6601 <title>Actions Files Tutorial</title>
6603 The above chapters have shown <link linkend="actions-file">which actions files
6604 there are and how they are organized</link>, how actions are <link
6605 linkend="actions">specified</link> and <link linkend="actions-apply">applied
6606 to URLs</link>, how <link linkend="af-patterns">patterns</link> work, and how to
6607 define and use <link linkend="aliases">aliases</link>. Now, let's look at an
6608 example <filename>match-all.action</filename>, <filename>default.action</filename>
6609 and <filename>user.action</filename> file and see how all these pieces come together:
6612 <sect3 id="match-all">
6613 <title>match-all.action</title>
6615 Remember <emphasis>all actions are disabled when matching starts</emphasis>,
6616 so we have to explicitly enable the ones we want.
6620 While the <filename>match-all.action</filename> file only contains a
6621 single section, it is probably the most important one. It has only one
6622 pattern, <quote><literal>/</literal></quote>, but this pattern
6623 <link linkend="af-patterns">matches all URLs</link>. Therefore, the set of
6624 actions used in this <quote>default</quote> section <emphasis>will
6625 be applied to all requests as a start</emphasis>. It can be partly or
6626 wholly overridden by other actions files like <filename>default.action</filename>
6627 and <filename>user.action</filename>, but it will still be largely responsible
6628 for your overall browsing experience.
6632 Again, at the start of matching, all actions are disabled, so there is
6633 no need to disable any actions here. (Remember: a <quote>+</quote>
6634 preceding the action name enables the action, a <quote>-</quote> disables!).
6635 Also note how this long line has been made more readable by splitting it into
6636 multiple lines with line continuation.
6641 +<link linkend="CHANGE-X-FORWARDED-FOR">change-x-forwarded-for{block}</link> \
6642 +<link linkend="HIDE-FROM-HEADER">hide-from-header{block}</link> \
6643 +<link linkend="SET-IMAGE-BLOCKER">set-image-blocker{pattern}</link> \
6649 The default behavior is now set.
6653 <sect3 id="default-action">
6654 <title>default.action</title>
6657 If you aren't a developer, there's no need for you to edit the
6658 <filename>default.action</filename> file. It is maintained by
6659 the &my-app; developers and if you disagree with some of the
6660 sections, you should overrule them in your <filename>user.action</filename>.
6664 Understanding the <filename>default.action</filename> file can
6665 help you with your <filename>user.action</filename>, though.
6669 The first section in this file is a special section for internal use
6670 that prevents older &my-app; versions from reading the file:
6674 ##########################################################################
6675 # Settings -- Don't change! For internal Privoxy use ONLY.
6676 ##########################################################################
6678 for-privoxy-version=3.0.11</screen>
6681 After that comes the (optional) alias section. We'll use the example
6682 section from the above <link linkend="aliases">chapter on aliases</link>,
6683 that also explains why and how aliases are used:
6687 ##########################################################################
6689 ##########################################################################
6692 # These aliases just save typing later:
6693 # (Note that some already use other aliases!)
6695 +crunch-all-cookies = +<link linkend="CRUNCH-INCOMING-COOKIES">crunch-incoming-cookies</link> +<link linkend="CRUNCH-OUTGOING-COOKIES">crunch-outgoing-cookies</link>
6696 -crunch-all-cookies = -<link linkend="CRUNCH-INCOMING-COOKIES">crunch-incoming-cookies</link> -<link linkend="CRUNCH-OUTGOING-COOKIES">crunch-outgoing-cookies</link>
6697 +block-as-image = +block{Blocked image.} +handle-as-image
6698 mercy-for-cookies = -crunch-all-cookies -<link linkend="SESSION-COOKIES-ONLY">session-cookies-only</link> -<link linkend="FILTER-CONTENT-COOKIES">filter{content-cookies}</link>
6700 # These aliases define combinations of actions
6701 # that are useful for certain types of sites:
6703 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>
6704 shop = -crunch-all-cookies -<link linkend="FILTER-ALL-POPUPS">filter{all-popups}</link></screen>
6707 The first of our specialized sections is concerned with <quote>fragile</quote>
6708 sites, i.e. sites that require minimum interference, because they are either
6709 very complex or very keen on tracking you (and have mechanisms in place that
6710 make them unusable for people who avoid being tracked). We will use
6711 our pre-defined <literal>fragile</literal> alias instead of stating the list
6712 of actions explicitly:
6716 ##########################################################################
6717 # Exceptions for sites that'll break under the default action set:
6718 ##########################################################################
6720 # "Fragile" Use a minimum set of actions for these sites (see alias above):
6723 .office.microsoft.com # surprise, surprise!
6724 .windowsupdate.microsoft.com
6725 mail.google.com</screen>
6728 Shopping sites are not as fragile, but they typically
6729 require cookies to log in, and pop-up windows for shopping
6730 carts or item details. Again, we'll use a pre-defined alias:
6738 .worldpay.com # for quietpc.com
6740 .scan.co.uk</screen>
6743 The <literal><link linkend="FAST-REDIRECTS">fast-redirects</link></literal>
6744 action, which may have been enabled in <filename>match-all.action</filename>,
6745 breaks some sites. So disable it for popular sites where we know it misbehaves:
6749 { -<link linkend="FAST-REDIRECTS">fast-redirects</link> }
6753 .altavista.com/.*(like|url|link):http
6754 .altavista.com/trans.*urltext=http
6755 .nytimes.com</screen>
6758 It is important that <application>Privoxy</application> knows which
6759 URLs belong to images, so that <emphasis>if</emphasis> they are to
6760 be blocked, a substitute image can be sent, rather than an HTML page.
6761 Contacting the remote site to find out is not an option, since it
6762 would destroy the loading time advantage of banner blocking, and it
6763 would feed the advertisers information about you. We can mark any
6764 URL as an image with the <literal><link
6765 linkend="handle-as-image">handle-as-image</link></literal> action,
6766 and marking all URLs that end in a known image file extension is a
6771 ##########################################################################
6773 ##########################################################################
6775 # Define which file types will be treated as images, in case they get
6776 # blocked further down this file:
6778 { +<link linkend="HANDLE-AS-IMAGE">handle-as-image</link> }
6779 /.*\.(gif|jpe?g|png|bmp|ico)$</screen>
6782 And then there are known banner sources. They often use scripts to
6783 generate the banners, so it won't be visible from the URL that the
6784 request is for an image. Hence we block them <emphasis>and</emphasis>
6785 mark them as images in one go, with the help of our
6786 <literal>+block-as-image</literal> alias defined above. (We could of
6787 course just as well use <literal>+<link linkend="block">block</link>
6788 +<link linkend="handle-as-image">handle-as-image</link></literal> here.)
6789 Remember that the type of the replacement image is chosen by the
6790 <literal><link linkend="set-image-blocker">set-image-blocker</link></literal>
6791 action. Since all URLs have matched the default section with its
6792 <literal>+<link linkend="set-image-blocker">set-image-blocker</link>{pattern}</literal>
6793 action before, it still applies and needn't be repeated:
6797 # Known ad generators:
6802 .ad.*.doubleclick.net
6803 .a.yimg.com/(?:(?!/i/).)*$
6804 .a[0-9].yimg.com/(?:(?!/i/).)*$
6809 One of the most important jobs of <application>Privoxy</application>
6810 is to block banners. Many of these can be <quote>blocked</quote>
6811 by the <literal><link linkend="filter">filter</link>{banners-by-size}</literal>
6812 action, which we enabled above, and which deletes the references to banner
6813 images from the pages while they are loaded, so the browser doesn't request
6814 them anymore, and hence they don't need to be blocked here. But this naturally
6815 doesn't catch all banners, and some people choose not to use filters, so we
6816 need a comprehensive list of patterns for banner URLs here, and apply the
6817 <literal><link linkend="block">block</link></literal> action to them.
6820 First comes many generic patterns, which do most of the work, by
6821 matching typical domain and path name components of banners. Then comes
6822 a list of individual patterns for specific sites, which is omitted here
6823 to keep the example short:
6827 ##########################################################################
6828 # Block these fine banners:
6829 ##########################################################################
6830 { <link linkend="BLOCK">+block{Banner ads.}</link> }
6838 /.*count(er)?\.(pl|cgi|exe|dll|asp|php[34]?)
6839 /(?:.*/)?(publicite|werbung|rekla(ma|me|am)|annonse|maino(kset|nta|s)?)/
6841 # Site-specific patterns (abbreviated):
6843 .hitbox.com</screen>
6846 It's quite remarkable how many advertisers actually call their banner
6847 servers ads.<replaceable>company</replaceable>.com, or call the directory
6848 in which the banners are stored literally <quote>banners</quote>. So the above
6849 generic patterns are surprisingly effective.
6852 But being very generic, they necessarily also catch URLs that we don't want
6853 to block. The pattern <literal>.*ads.</literal> e.g. catches
6854 <quote>nasty-<emphasis>ads</emphasis>.nasty-corp.com</quote> as intended,
6855 but also <quote>downlo<emphasis>ads</emphasis>.sourcefroge.net</quote> or
6856 <quote><emphasis>ads</emphasis>l.some-provider.net.</quote> So here come some
6857 well-known exceptions to the <literal>+<link linkend="BLOCK">block</link></literal>
6861 Note that these are exceptions to exceptions from the default! Consider the URL
6862 <quote>downloads.sourcefroge.net</quote>: Initially, all actions are deactivated,
6863 so it wouldn't get blocked. Then comes the defaults section, which matches the
6864 URL, but just deactivates the <literal><link linkend="BLOCK">block</link></literal>
6865 action once again. Then it matches <literal>.*ads.</literal>, an exception to the
6866 general non-blocking policy, and suddenly
6867 <literal><link linkend="BLOCK">+block</link></literal> applies. And now, it'll match
6868 <literal>.*loads.</literal>, where <literal><link linkend="BLOCK">-block</link></literal>
6869 applies, so (unless it matches <emphasis>again</emphasis> further down) it ends up
6870 with no <literal><link linkend="BLOCK">block</link></literal> action applying.
6874 ##########################################################################
6875 # Save some innocent victims of the above generic block patterns:
6876 ##########################################################################
6880 { -<link linkend="BLOCK">block</link> }
6881 adv[io]*. # (for advogato.org and advice.*)
6882 adsl. # (has nothing to do with ads)
6883 adobe. # (has nothing to do with ads either)
6884 ad[ud]*. # (adult.* and add.*)
6885 .edu # (universities don't host banners (yet!))
6886 .*loads. # (downloads, uploads etc)
6894 www.globalintersec.com/adv # (adv = advanced)
6895 www.ugu.com/sui/ugu/adv</screen>
6898 Filtering source code can have nasty side effects,
6899 so make an exception for our friends at sourceforge.net,
6900 and all paths with <quote>cvs</quote> in them. Note that
6901 <literal>-<link linkend="FILTER">filter</link></literal>
6902 disables <emphasis>all</emphasis> filters in one fell swoop!
6906 # Don't filter code!
6908 { -<link linkend="FILTER">filter</link> }
6913 .sourceforge.net</screen>
6916 The actual <filename>default.action</filename> is of course much more
6917 comprehensive, but we hope this example made clear how it works.
6922 <sect3 id="user-action"><title>user.action</title>
6925 So far we are painting with a broad brush by setting general policies,
6926 which would be a reasonable starting point for many people. Now,
6927 you might want to be more specific and have customized rules that
6928 are more suitable to your personal habits and preferences. These would
6929 be for narrowly defined situations like your ISP or your bank, and should
6930 be placed in <filename>user.action</filename>, which is parsed after all other
6931 actions files and hence has the last word, over-riding any previously
6932 defined actions. <filename>user.action</filename> is also a
6933 <emphasis>safe</emphasis> place for your personal settings, since
6934 <filename>default.action</filename> is actively maintained by the
6935 <application>Privoxy</application> developers and you'll probably want
6936 to install updated versions from time to time.
6940 So let's look at a few examples of things that one might typically do in
6941 <filename>user.action</filename>:
6945 <!-- brief sample user.action here -->
6948 # My user.action file. <fred@example.com></screen>
6951 As <link linkend="aliases">aliases</link> are local to the actions
6952 file that they are defined in, you can't use the ones from
6953 <filename>default.action</filename>, unless you repeat them here:
6957 # Aliases are local to the file they are defined in.
6958 # (Re-)define aliases for this file:
6962 # These aliases just save typing later, and the alias names should
6963 # be self explanatory.
6965 +crunch-all-cookies = +crunch-incoming-cookies +crunch-outgoing-cookies
6966 -crunch-all-cookies = -crunch-incoming-cookies -crunch-outgoing-cookies
6967 allow-all-cookies = -crunch-all-cookies -session-cookies-only
6968 allow-popups = -filter{all-popups}
6969 +block-as-image = +block{Blocked as image.} +handle-as-image
6970 -block-as-image = -block
6972 # These aliases define combinations of actions that are useful for
6973 # certain types of sites:
6975 fragile = -block -crunch-all-cookies -filter -fast-redirects -hide-referrer
6976 shop = -crunch-all-cookies allow-popups
6978 # Allow ads for selected useful free sites:
6980 allow-ads = -block -filter{banners-by-size} -filter{banners-by-link}
6982 # Alias for specific file types that are text, but might have conflicting
6983 # MIME types. We want the browser to force these to be text documents.
6984 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>
6987 Say you have accounts on some sites that you visit regularly, and
6988 you don't want to have to log in manually each time. So you'd like
6989 to allow persistent cookies for these sites. The
6990 <literal>allow-all-cookies</literal> alias defined above does exactly
6991 that, i.e. it disables crunching of cookies in any direction, and the
6992 processing of cookies to make them only temporary.
6996 { allow-all-cookies }
7004 Your bank is allergic to some filter, but you don't know which, so you disable them all:
7008 { -<link linkend="FILTER">filter</link> }
7009 .your-home-banking-site.com
7013 Some file types you may not want to filter for various reasons:
7017 # Technical documentation is likely to contain strings that might
7018 # erroneously get altered by the JavaScript-oriented filters:
7023 # And this stupid host sends streaming video with a wrong MIME type,
7024 # so that Privoxy thinks it is getting HTML and starts filtering:
7026 stupid-server.example.com/</screen>
7029 Example of a simple <link linkend="BLOCK">block</link> action. Say you've
7030 seen an ad on your favourite page on example.com that you want to get rid of.
7031 You have right-clicked the image, selected <quote>copy image location</quote>
7032 and pasted the URL below while removing the leading http://, into a
7033 <literal>{ +block{} }</literal> section. Note that <literal>{ +handle-as-image
7034 }</literal> need not be specified, since all URLs ending in
7035 <literal>.gif</literal> will be tagged as images by the general rules as set
7036 in default.action anyway:
7040 { +<link linkend="BLOCK">block</link>{Nasty ads.} }
7041 www.example.com/nasty-ads/sponsor\.gif
7042 another.example.net/more/junk/here/
7046 The URLs of dynamically generated banners, especially from large banner
7047 farms, often don't use the well-known image file name extensions, which
7048 makes it impossible for <application>Privoxy</application> to guess
7049 the file type just by looking at the URL.
7050 You can use the <literal>+block-as-image</literal> alias defined above for
7052 Note that objects which match this rule but then turn out NOT to be an
7053 image are typically rendered as a <quote>broken image</quote> icon by the
7054 browser. Use cautiously.
7066 Now you noticed that the default configuration breaks Forbes Magazine,
7067 but you were too lazy to find out which action is the culprit, and you
7068 were again too lazy to give <link linkend="contact">feedback</link>, so
7069 you just used the <literal>fragile</literal> alias on the site, and
7070 -- <emphasis>whoa!</emphasis> -- it worked. The <literal>fragile</literal>
7071 aliases disables those actions that are most likely to break a site. Also,
7072 good for testing purposes to see if it is <application>Privoxy</application>
7073 that is causing the problem or not. We later find other regular sites
7074 that misbehave, and add those to our personalized list of troublemakers:
7085 You like the <quote>fun</quote> text replacements in <filename>default.filter</filename>,
7086 but it is disabled in the distributed actions file.
7087 So you'd like to turn it on in your private,
7088 update-safe config, once and for all:
7092 { +<link linkend="filter-fun">filter{fun}</link> }
7097 Note that the above is not really a good idea: There are exceptions
7098 to the filters in <filename>default.action</filename> for things that
7099 really shouldn't be filtered, like code on CVS->Web interfaces. Since
7100 <filename>user.action</filename> has the last word, these exceptions
7101 won't be valid for the <quote>fun</quote> filtering specified here.
7105 You might also worry about how your favourite free websites are
7106 funded, and find that they rely on displaying banner advertisements
7107 to survive. So you might want to specifically allow banners for those
7108 sites that you feel provide value to you:
7119 Note that <literal>allow-ads</literal> has been aliased to
7120 <literal>-<link linkend="block">block</link></literal>,
7121 <literal>-<link linkend="filter-banners-by-size">filter{banners-by-size}</link></literal>, and
7122 <literal>-<link linkend="filter-banners-by-link">filter{banners-by-link}</link></literal> above.
7126 Invoke another alias here to force an over-ride of the MIME type <literal>
7127 application/x-sh</literal> which typically would open a download type
7128 dialog. In my case, I want to look at the shell script, and then I can save
7129 it should I choose to.
7138 <filename>user.action</filename> is generally the best place to define
7139 exceptions and additions to the default policies of
7140 <filename>default.action</filename>. Some actions are safe to have their
7141 default policies set here though. So let's set a default policy to have a
7142 <quote>blank</quote> image as opposed to the checkerboard pattern for
7143 <emphasis>ALL</emphasis> sites. <quote>/</quote> of course matches all URL
7148 { +<link linkend="set-image-blocker">set-image-blocker{blank}</link> }
7149 / # ALL sites</screen>
7154 <!-- ~ End section ~ -->
7158 <!-- ~ End section ~ -->
7160 <!-- ~~~~~~~~ New section Header ~~~~~~~~~ -->
7162 <sect1 id="filter-file">
7163 <title>Filter Files</title>
7166 On-the-fly text substitutions need
7167 to be defined in a <quote>filter file</quote>. Once defined, they
7168 can then be invoked as an <quote>action</quote>.
7172 &my-app; supports four different pcrs-based filter actions:
7173 <literal><link linkend="filter">filter</link></literal> to
7174 rewrite the content that is send to the client,
7175 <literal><link linkend="client-header-filter">client-header-filter</link></literal>
7176 to rewrite headers that are send by the client,
7177 <literal><link linkend="server-header-filter">server-header-filter</link></literal>
7178 to rewrite headers that are send by the server, and
7179 <literal><link linkend="client-body-filter">client-body-filter</link></literal>
7180 to rewrite client request body.
7184 &my-app; also supports three tagger actions:
7185 <literal><link linkend="client-header-tagger">client-header-tagger</link></literal>,
7186 <literal><link linkend="client-body-tagger">client-body-tagger</link></literal>
7188 <literal><link linkend="server-header-tagger">server-header-tagger</link></literal>.
7189 Taggers and filters use the same syntax in the filter files, the difference
7190 is that taggers don't modify the text they are filtering, but use a rewritten
7191 version of the filtered text as tag. The tags can then be used to change the
7192 applying actions through sections with <link linkend="tag-pattern">tag-patterns</link>.
7196 Finally &my-app; supports the
7197 <literal><link linkend="external-filter">external-filter</link></literal> action
7198 to enable <literal><link linkend="external-filter-syntax">external filters</link></literal>
7199 written in proper programming languages.
7204 Multiple filter files can be defined through the <literal> <link
7205 linkend="filterfile">filterfile</link></literal> config directive. The filters
7206 as supplied by the developers are located in
7207 <filename>default.filter</filename>. It is recommended that any locally
7208 defined or modified filters go in a separately defined file such as
7209 <filename>user.filter</filename>.
7213 Common tasks for content filters are to eliminate common annoyances in
7214 HTML and JavaScript, such as pop-up windows,
7215 exit consoles, crippled windows without navigation tools, the
7216 infamous <BLINK> tag etc, to suppress images with certain
7217 width and height attributes (standard banner sizes or web-bugs),
7218 or just to have fun.
7222 Enabled content filters are applied to any content whose
7223 <quote>Content Type</quote> header is recognised as a sign
7224 of text-based content, with the exception of <literal>text/plain</literal>.
7225 Use the <link linkend="FORCE-TEXT-MODE">force-text-mode</link> action
7226 to also filter other content.
7230 Substitutions are made at the source level, so if you want to <quote>roll
7231 your own</quote> filters, you should first be familiar with HTML syntax,
7232 and, of course, regular expressions.
7236 Just like the <link linkend="actions-file">actions files</link>, the
7237 filter file is organized in sections, which are called <emphasis>filters</emphasis>
7238 here. Each filter consists of a heading line, that starts with one of the
7239 <emphasis>keywords</emphasis> <literal>FILTER:</literal>,
7240 <literal>CLIENT-HEADER-FILTER:</literal>, <literal>SERVER-HEADER-FILTER:</literal> or
7241 <literal>CLIENT-BODY-FILTER:</literal>
7242 followed by the filter's <emphasis>name</emphasis>, and a short (one line)
7243 <emphasis>description</emphasis> of what it does. Below that line
7244 come the <emphasis>jobs</emphasis>, i.e. lines that define the actual
7245 text substitutions. By convention, the name of a filter
7246 should describe what the filter <emphasis>eliminates</emphasis>. The
7247 comment is used in the <ulink url="http://config.privoxy.org/">web-based
7248 user interface</ulink>.
7252 Once a filter called <replaceable>name</replaceable> has been defined
7253 in the filter file, it can be invoked by using an action of the form
7254 +<literal><link linkend="filter">filter</link>{<replaceable>name</replaceable>}</literal>
7255 in any <link linkend="actions-file">actions file</link>.
7259 Filter definitions start with a header line that contains the filter
7260 type, the filter name and the filter description.
7261 A content filter header line for a filter called <quote>foo</quote> could look
7265 <screen>FILTER: foo Replace all "foo" with "bar"</screen>
7268 Below that line, and up to the next header line, come the jobs that
7269 define what text replacements the filter executes. They are specified
7270 in a syntax that imitates <ulink url="http://www.perl.org/">Perl</ulink>'s
7271 <literal>s///</literal> operator. If you are familiar with Perl, you
7272 will find this to be quite intuitive, and may want to look at the
7273 PCRS documentation for the subtle differences to Perl behaviour.
7277 Most notably, the non-standard option letter <literal>U</literal> is supported,
7278 which turns the default to ungreedy matching (add <literal>?</literal> to
7279 quantifiers to turn them greedy again).
7283 The non-standard option letter <literal>D</literal> (dynamic) allows
7284 to use the variables $host, $origin (the IP address the request came from),
7285 $path, $url and $listen-address (the address on which Privoxy accepted the
7286 client request. Example: 127.0.0.1:8118).
7287 They will be replaced with the value they refer to before the filter
7292 Note that '$' is a bad choice for a delimiter in a dynamic filter as you
7293 might end up with unintended variables if you use a variable name
7294 directly after the delimiter. Variables will be resolved without
7295 escaping anything, therefore you also have to be careful not to chose
7296 delimiters that appear in the replacement text. For example '<' should
7297 be save, while '?' will sooner or later cause conflicts with $url.
7301 The non-standard option letter <literal>T</literal> (trivial) prevents
7302 parsing for backreferences in the substitute. Use it if you want to include
7303 text like '$&' in your substitute without quoting.
7308 <ulink url="https://en.wikipedia.org/wiki/Regular_expressions"><quote>Regular
7309 Expressions</quote></ulink>, you might want to take a look at
7310 the <link linkend="regex">Appendix on regular expressions</link>, and
7311 see the <ulink url="http://perldoc.perl.org/perlre.html">Perl
7313 <ulink url="http://perldoc.perl.org/perlop.html">the
7314 <literal>s///</literal> operator's syntax</ulink> and <ulink
7315 url="http://perldoc.perl.org/perlre.html">Perl-style regular
7316 expressions</ulink> in general.
7317 The below examples might also help to get you started.
7321 <!-- ~~~~~~~~ New section Header ~~~~~~~~~ -->
7323 <sect2 id="filter-file-tut"><title>Filter File Tutorial</title>
7325 Now, let's complete our <quote>foo</quote> content filter. We have already defined
7326 the heading, but the jobs are still missing. Since all it does is to replace
7327 <quote>foo</quote> with <quote>bar</quote>, there is only one (trivial) job
7331 <screen>s/foo/bar/</screen>
7334 But wait! Didn't the comment say that <emphasis>all</emphasis> occurrences
7335 of <quote>foo</quote> should be replaced? Our current job will only take
7336 care of the first <quote>foo</quote> on each page. For global substitution,
7337 we'll need to add the <literal>g</literal> option:
7340 <screen>s/foo/bar/g</screen>
7343 Our complete filter now looks like this:
7346 <screen>FILTER: foo Replace all "foo" with "bar"
7347 s/foo/bar/g</screen>
7350 Let's look at some real filters for more interesting examples. Here you see
7351 a filter that protects against some common annoyances that arise from JavaScript
7352 abuse. Let's look at its jobs one after the other:
7357 FILTER: js-annoyances Get rid of particularly annoying JavaScript abuse
7359 # Get rid of JavaScript referrer tracking. Test page: http://www.randomoddness.com/untitled.htm
7361 s|(<script.*)document\.referrer(.*</script>)|$1"Not Your Business!"$2|Usg</screen>
7364 Following the header line and a comment, you see the job. Note that it uses
7365 <literal>|</literal> as the delimiter instead of <literal>/</literal>, because
7366 the pattern contains a forward slash, which would otherwise have to be escaped
7367 by a backslash (<literal>\</literal>).
7371 Now, let's examine the pattern: it starts with the text <literal><script.*</literal>
7372 enclosed in parentheses. Since the dot matches any character, and <literal>*</literal>
7373 means: <quote>Match an arbitrary number of the element left of myself</quote>, this
7374 matches <quote><script</quote>, followed by <emphasis>any</emphasis> text, i.e.
7375 it matches the whole page, from the start of the first <script> tag.
7379 That's more than we want, but the pattern continues: <literal>document\.referrer</literal>
7380 matches only the exact string <quote>document.referrer</quote>. The dot needed to
7381 be <emphasis>escaped</emphasis>, i.e. preceded by a backslash, to take away its
7382 special meaning as a joker, and make it just a regular dot. So far, the meaning is:
7383 Match from the start of the first <script> tag in a the page, up to, and including,
7384 the text <quote>document.referrer</quote>, if <emphasis>both</emphasis> are present
7385 in the page (and appear in that order).
7389 But there's still more pattern to go. The next element, again enclosed in parentheses,
7390 is <literal>.*</script></literal>. You already know what <literal>.*</literal>
7391 means, so the whole pattern translates to: Match from the start of the first <script>
7392 tag in a page to the end of the last <script> tag, provided that the text
7393 <quote>document.referrer</quote> appears somewhere in between.
7397 This is still not the whole story, since we have ignored the options and the parentheses:
7398 The portions of the page matched by sub-patterns that are enclosed in parentheses, will be
7399 remembered and be available through the variables <literal>$1, $2, ...</literal> in
7400 the substitute. The <literal>U</literal> option switches to ungreedy matching, which means
7401 that the first <literal>.*</literal> in the pattern will only <quote>eat up</quote> all
7402 text in between <quote><script</quote> and the <emphasis>first</emphasis> occurrence
7403 of <quote>document.referrer</quote>, and that the second <literal>.*</literal> will
7404 only span the text up to the <emphasis>first</emphasis> <quote></script></quote>
7405 tag. Furthermore, the <literal>s</literal> option says that the match may span
7406 multiple lines in the page, and the <literal>g</literal> option again means that the
7407 substitution is global.
7411 So, to summarize, the pattern means: Match all scripts that contain the text
7412 <quote>document.referrer</quote>. Remember the parts of the script from
7413 (and including) the start tag up to (and excluding) the string
7414 <quote>document.referrer</quote> as <literal>$1</literal>, and the part following
7415 that string, up to and including the closing tag, as <literal>$2</literal>.
7419 Now the pattern is deciphered, but wasn't this about substituting things? So
7420 lets look at the substitute: <literal>$1"Not Your Business!"$2</literal> is
7421 easy to read: The text remembered as <literal>$1</literal>, followed by
7422 <literal>"Not Your Business!"</literal> (<emphasis>including</emphasis>
7423 the quotation marks!), followed by the text remembered as <literal>$2</literal>.
7424 This produces an exact copy of the original string, with the middle part
7425 (the <quote>document.referrer</quote>) replaced by <literal>"Not Your
7426 Business!"</literal>.
7430 The whole job now reads: Replace <quote>document.referrer</quote> by
7431 <literal>"Not Your Business!"</literal> wherever it appears inside a
7432 <script> tag. Note that this job won't break JavaScript syntax,
7433 since both the original and the replacement are syntactically valid
7434 string objects. The script just won't have access to the referrer
7435 information anymore.
7439 We'll show you two other jobs from the JavaScript taming department, but
7440 this time only point out the constructs of special interest:
7444 # The status bar is for displaying link targets, not pointless blahblah
7446 s/window\.status\s*=\s*(['"]).*?\1/dUmMy=1/ig</screen>
7449 <literal>\s</literal> stands for whitespace characters (space, tab, newline,
7450 carriage return, form feed), so that <literal>\s*</literal> means: <quote>zero
7451 or more whitespace</quote>. The <literal>?</literal> in <literal>.*?</literal>
7452 makes this matching of arbitrary text ungreedy. (Note that the <literal>U</literal>
7453 option is not set). The <literal>['"]</literal> construct means: <quote>a single
7454 <emphasis>or</emphasis> a double quote</quote>. Finally, <literal>\1</literal> is
7455 a back-reference to the first parenthesis just like <literal>$1</literal> above,
7456 with the difference that in the <emphasis>pattern</emphasis>, a backslash indicates
7457 a back-reference, whereas in the <emphasis>substitute</emphasis>, it's the dollar.
7461 So what does this job do? It replaces assignments of single- or double-quoted
7462 strings to the <quote>window.status</quote> object with a dummy assignment
7463 (using a variable name that is hopefully odd enough not to conflict with
7464 real variables in scripts). Thus, it catches many cases where e.g. pointless
7465 descriptions are displayed in the status bar instead of the link target when
7466 you move your mouse over links.
7470 # Kill OnUnload popups. Yummy. Test: http://www.zdnet.com/zdsubs/yahoo/tree/yfs.html
7472 s/(<body [^>]*)onunload(.*>)/$1never$2/iU</screen>
7476 <ulink url="http://www.w3.org/TR/2000/REC-DOM-Level-2-Events-20001113/events.html#Events-eventgroupings-htmlevents">OnUnload
7477 event binding</ulink> in the HTML DOM was a <emphasis>CRIME</emphasis>.
7478 When I close a browser window, I want it to close and die. Basta.
7479 This job replaces the <quote>onunload</quote> attribute in
7480 <quote><body></quote> tags with the dummy word <literal>never</literal>.
7481 Note that the <literal>i</literal> option makes the pattern matching
7482 case-insensitive. Also note that ungreedy matching alone doesn't always guarantee
7483 a minimal match: In the first parenthesis, we had to use <literal>[^>]*</literal>
7484 instead of <literal>.*</literal> to prevent the match from exceeding the
7485 <body> tag if it doesn't contain <quote>OnUnload</quote>, but the page's
7490 The last example is from the fun department:
7494 FILTER: fun Fun text replacements
7496 # Spice the daily news:
7498 s/microsoft(?!\.com)/MicroSuck/ig</screen>
7501 Note the <literal>(?!\.com)</literal> part (a so-called negative lookahead)
7502 in the job's pattern, which means: Don't match, if the string
7503 <quote>.com</quote> appears directly following <quote>microsoft</quote>
7504 in the page. This prevents links to microsoft.com from being trashed, while
7505 still replacing the word everywhere else.
7509 # Buzzword Bingo (example for extended regex syntax)
7511 s* industry[ -]leading \
7513 | customer[ -]focused \
7514 | market[ -]driven \
7515 | award[ -]winning # Comments are OK, too! \
7516 | high[ -]performance \
7517 | solutions[ -]based \
7521 *<font color="red"><b>BINGO!</b></font> \
7525 The <literal>x</literal> option in this job turns on extended syntax, and allows for
7526 e.g. the liberal use of (non-interpreted!) whitespace for nicer formatting.
7534 <!-- ~~~~~~~~ New section Header ~~~~~~~~~ -->
7536 <sect2 id="predefined-filters"><title>The Pre-defined Filters</title>
7540 Note each filter is also listed in the +filter action section above. Please
7541 keep these listings in sync.
7546 The distribution <filename>default.filter</filename> file contains a selection of
7547 pre-defined filters for your convenience:
7552 <term><emphasis>js-annoyances</emphasis></term>
7555 The purpose of this filter is to get rid of particularly annoying JavaScript abuse.
7561 replaces JavaScript references to the browser's referrer information
7562 with the string "Not Your Business!". This compliments the <literal><link
7563 linkend="hide-referrer">hide-referrer</link></literal> action on the content level.
7568 removes the bindings to the DOM's
7569 <ulink url="http://www.w3.org/TR/2000/REC-DOM-Level-2-Events-20001113/events.html#Events-eventgroupings-htmlevents">unload
7570 event</ulink> which we feel has no right to exist and is responsible for most <quote>exit consoles</quote>, i.e.
7571 nasty windows that pop up when you close another one.
7576 removes code that causes new windows to be opened with undesired properties, such as being
7577 full-screen, non-resizeable, without location, status or menu bar etc.
7582 Use with caution. This is an aggressive filter, and can break sites that
7583 rely heavily on JavaScript.
7589 <term><emphasis>js-events</emphasis></term>
7592 This is a very radical measure. It removes virtually all JavaScript event bindings, which
7593 means that scripts can not react to user actions such as mouse movements or clicks, window
7594 resizing etc, anymore. Use with caution!
7597 We <emphasis>strongly discourage</emphasis> using this filter as a default since it breaks
7598 many legitimate scripts. It is meant for use only on extra-nasty sites (should you really
7605 <term><emphasis>html-annoyances</emphasis></term>
7608 This filter will undo many common instances of HTML based abuse.
7611 The <literal>BLINK</literal> and <literal>MARQUEE</literal> tags
7612 are neutralized (yeah baby!), and browser windows will be created as
7613 resizeable (as of course they should be!), and will have location,
7614 scroll and menu bars -- even if specified otherwise.
7620 <term><emphasis>content-cookies</emphasis></term>
7623 Most cookies are set in the HTTP dialog, where they can be intercepted
7625 <literal><link linkend="crunch-incoming-cookies">crunch-incoming-cookies</link></literal>
7626 and <literal><link linkend="crunch-outgoing-cookies">crunch-outgoing-cookies</link></literal>
7627 actions. But web sites increasingly make use of HTML meta tags and JavaScript
7628 to sneak cookies to the browser on the content level.
7631 This filter disables most HTML and JavaScript code that reads or sets
7632 cookies. It cannot detect all clever uses of these types of code, so it
7633 should not be relied on as an absolute fix. Use it wherever you would also
7634 use the cookie crunch actions.
7640 <term><emphasis>refresh-tags</emphasis></term>
7643 Disable any refresh tags if the interval is greater than nine seconds (so
7644 that redirections done via refresh tags are not destroyed). This is useful
7645 for dial-on-demand setups, or for those who find this HTML feature
7652 <term><emphasis>unsolicited-popups</emphasis></term>
7655 This filter attempts to prevent only <quote>unsolicited</quote> pop-up
7656 windows from opening, yet still allow pop-up windows that the user
7657 has explicitly chosen to open. It was added in version 3.0.1,
7658 as an improvement over earlier such filters.
7661 Technical note: The filter works by redefining the window.open JavaScript
7662 function to a dummy function, <literal>PrivoxyWindowOpen()</literal>,
7663 during the loading and rendering phase of each HTML page access, and
7664 restoring the function afterward.
7667 This is recommended only for browsers that cannot perform this function
7668 reliably themselves. And be aware that some sites require such windows
7669 in order to function normally. Use with caution.
7675 <term><emphasis>all-popups</emphasis></term>
7678 Attempt to prevent <emphasis>all</emphasis> pop-up windows from opening.
7679 Note this should be used with even more discretion than the above, since
7680 it is more likely to break some sites that require pop-ups for normal
7681 usage. Use with caution.
7687 <term><emphasis>img-reorder</emphasis></term>
7690 This is a helper filter that has no value if used alone. It makes the
7691 <literal>banners-by-size</literal> and <literal>banners-by-link</literal>
7692 (see below) filters more effective and should be enabled together with them.
7698 <term><emphasis>banners-by-size</emphasis></term>
7701 This filter removes image tags purely based on what size they are. Fortunately
7702 for us, many ads and banner images tend to conform to certain standardized
7703 sizes, which makes this filter quite effective for ad stripping purposes.
7706 Occasionally this filter will cause false positives on images that are not ads,
7707 but just happen to be of one of the standard banner sizes.
7710 Recommended only for those who require extreme ad blocking. The default
7711 block rules should catch 95+% of all ads <emphasis>without</emphasis> this filter enabled.
7717 <term><emphasis>banners-by-link</emphasis></term>
7720 This filter attempts to kill any banners if their URLs seem to point
7721 to known or suspected click trackers. It is currently not of much value
7722 and is not recommended for use by default.
7728 <term><emphasis>webbugs</emphasis></term>
7731 Webbugs are small, invisible images (technically 1X1 GIF images), that
7732 are used to track users across websites, and collect information on them.
7733 As an HTML page is loaded by the browser, an embedded image tag causes the
7734 browser to contact a third-party site, disclosing the tracking information
7735 through the requested URL and/or cookies for that third-party domain, without
7736 the user ever becoming aware of the interaction with the third-party site.
7737 HTML-ized spam also uses a similar technique to verify email addresses.
7740 This filter removes the HTML code that loads such <quote>webbugs</quote>.
7746 <term><emphasis>tiny-textforms</emphasis></term>
7749 A rather special-purpose filter that can be used to enlarge textareas (those
7750 multi-line text boxes in web forms) and turn off hard word wrap in them.
7751 It was written for the sourceforge.net tracker system where such boxes are
7752 a nuisance, but it can be handy on other sites, too.
7755 It is not recommended to use this filter as a default.
7761 <term><emphasis>jumping-windows</emphasis></term>
7764 Many consider windows that move, or resize themselves to be abusive. This filter
7765 neutralizes the related JavaScript code. Note that some sites might not display
7766 or behave as intended when using this filter. Use with caution.
7772 <term><emphasis>frameset-borders</emphasis></term>
7775 Some web designers seem to assume that everyone in the world will view their
7776 web sites using the same browser brand and version, screen resolution etc,
7777 because only that assumption could explain why they'd use static frame sizes,
7778 yet prevent their frames from being resized by the user, should they be too
7779 small to show their whole content.
7782 This filter removes the related HTML code. It should only be applied to sites
7789 <term><emphasis>demoronizer</emphasis></term>
7792 Many Microsoft products that generate HTML use non-standard extensions (read:
7793 violations) of the ISO 8859-1 aka Latin-1 character set. This can cause those
7794 HTML documents to display with errors on standard-compliant platforms.
7797 This filter translates the MS-only characters into Latin-1 equivalents.
7798 It is not necessary when using MS products, and will cause corruption of
7799 all documents that use 8-bit character sets other than Latin-1. It's mostly
7800 worthwhile for Europeans on non-MS platforms, if weird garbage characters
7801 sometimes appear on some pages, or user agents that don't correct for this on
7804 My version of Mozilla (ancient) shows little square boxes for quote
7805 characters, and apostrophes on moronized pages. So many pages have this, I
7806 can read them fine now. HB 08/27/06
7813 <term><emphasis>shockwave-flash</emphasis></term>
7816 A filter for shockwave haters. As the name suggests, this filter strips code
7817 out of web pages that is used to embed shockwave flash objects.
7825 <term><emphasis>quicktime-kioskmode</emphasis></term>
7828 Change HTML code that embeds Quicktime objects so that kioskmode, which
7829 prevents saving, is disabled.
7835 <term><emphasis>fun</emphasis></term>
7838 Text replacements for subversive browsing fun. Make fun of your favorite
7839 Monopolist or play buzzword bingo.
7845 <term><emphasis>crude-parental</emphasis></term>
7848 A demonstration-only filter that shows how <application>Privoxy</application>
7849 can be used to delete web content on a keyword basis.
7855 <term><emphasis>ie-exploits</emphasis></term>
7858 An experimental collection of text replacements to disable malicious HTML and JavaScript
7859 code that exploits known security holes in Internet Explorer.
7862 Presently, it only protects against Nimda and a cross-site scripting bug, and
7863 would need active maintenance to provide more substantial protection.
7869 <term><emphasis>site-specifics</emphasis></term>
7872 Some web sites have very specific problems, the cure for which doesn't apply
7873 anywhere else, or could even cause damage on other sites.
7876 This is a collection of such site-specific cures which should only be applied
7877 to the sites they were intended for, which is what the supplied
7878 <filename>default.action</filename> file does. Users shouldn't need to change
7879 anything regarding this filter.
7885 <term><emphasis>google</emphasis></term>
7888 A CSS based block for Google text ads. Also removes a width limitation
7889 and the toolbar advertisement.
7895 <term><emphasis>yahoo</emphasis></term>
7898 Another CSS based block, this time for Yahoo text ads. And removes
7899 a width limitation as well.
7905 <term><emphasis>msn</emphasis></term>
7908 Another CSS based block, this time for MSN text ads. And removes
7909 tracking URLs, as well as a width limitation.
7915 <term><emphasis>blogspot</emphasis></term>
7918 Cleans up some Blogspot blogs. Read the fine print before using this one!
7921 This filter also intentionally removes some navigation stuff and sets the
7922 page width to 100%. As a result, some rounded <quote>corners</quote> would
7923 appear to early or not at all and as fixing this would require a browser
7924 that understands background-size (CSS3), they are removed instead.
7930 <term><emphasis>xml-to-html</emphasis></term>
7933 Server-header filter to change the Content-Type from xml to html.
7939 <term><emphasis>html-to-xml</emphasis></term>
7942 Server-header filter to change the Content-Type from html to xml.
7948 <term><emphasis>no-ping</emphasis></term>
7951 Removes the non-standard <literal>ping</literal> attribute from
7952 anchor and area HTML tags.
7958 <term><emphasis>hide-tor-exit-notation</emphasis></term>
7961 Client-header filter to remove the <command>Tor</command> exit node notation
7962 found in Host and Referer headers.
7965 If &my-app; and <command>Tor</command> are chained and &my-app;
7966 is configured to use socks4a, one can use <quote>http://www.example.org.foobar.exit/</quote>
7967 to access the host <quote>www.example.org</quote> through the
7968 <command>Tor</command> exit node <quote>foobar</quote>.
7971 As the HTTP client isn't aware of this notation, it treats the
7972 whole string <quote>www.example.org.foobar.exit</quote> as host and uses it
7973 for the <quote>Host</quote> and <quote>Referer</quote> headers. From the
7974 server's point of view the resulting headers are invalid and can cause problems.
7977 An invalid <quote>Referer</quote> header can trigger <quote>hot-linking</quote>
7978 protections, an invalid <quote>Host</quote> header will make it impossible for
7979 the server to find the right vhost (several domains hosted on the same IP address).
7982 This client-header filter removes the <quote>foo.exit</quote> part in those headers
7983 to prevent the mentioned problems. Note that it only modifies
7984 the HTTP headers, it doesn't make it impossible for the server
7985 to detect your <command>Tor</command> exit node based on the IP address
7986 the request is coming from.
7993 <term><emphasis> </emphasis></term>
8006 <!-- ~~~~~~~~ New section Header ~~~~~~~~~ -->
8007 <sect2 id="external-filter-syntax"><title>External filter syntax</title>
8009 External filters are scripts or programs that can modify the content in
8010 case common <literal><link linkend="filter">filters</link></literal>
8011 aren't powerful enough.
8014 External filters can be written in any language the platform &my-app; runs
8018 They are controlled with the
8019 <literal><link linkend="external-filter">external-filter</link></literal> action
8020 and have to be defined in the <literal><link linkend="filterfile">filterfile</link></literal>
8024 The header looks like any other filter, but instead of pcrs jobs, external
8025 filters contain a single job which can be a program or a shell script (which
8026 may call other scripts or programs).
8029 External filters read the content from STDIN and write the rewritten
8031 The environment variables PRIVOXY_URL, PRIVOXY_PATH, PRIVOXY_HOST,
8032 PRIVOXY_ORIGIN, PRIVOXY_LISTEN_ADDRESS can be used to get some details
8033 about the client request.
8036 &my-app; will temporary store the content to filter in the
8037 <literal><link linkend="temporary-directory">temporary-directory</link></literal>.
8041 EXTERNAL-FILTER: cat Pointless example filter that doesn't actually modify the content
8044 # Incorrect reimplementation of the filter above in POSIX shell.
8046 # Note that it's a single job that spans multiple lines, the line
8047 # breaks are not passed to the shell, thus the semicolons are required.
8049 # If the script isn't trivial, it is recommended to put it into an external file.
8051 # In general, writing external filters entirely in POSIX shell is not
8052 # considered a good idea.
8053 EXTERNAL-FILTER: cat2 Pointless example filter that despite its name may actually modify the content
8059 EXTERNAL-FILTER: rotate-image Rotate an image by 180 degree. Test filter with limited value.
8060 /usr/local/bin/convert - -rotate 180 -
8062 EXTERNAL-FILTER: citation-needed Adds a "[citation needed]" tag to an image. The coordinates may need adjustment.
8063 /usr/local/bin/convert - -pointsize 16 -fill white -annotate +17+418 "[citation needed]" -
8068 Currently external filters are executed with &my-app;'s privileges!
8069 Only use external filters you understand and trust.
8073 External filters are experimental and the syntax may change in the future.
8079 <!-- ~ End section ~ -->
8083 <!-- ~~~~~ New section ~~~~~ -->
8085 <sect1 id="templates">
8086 <title>Privoxy's Template Files</title>
8088 All <application>Privoxy</application> built-in pages, i.e. error pages such as the
8089 <ulink url="http://show-the-404-error.page"><quote>404 - No Such Domain</quote>
8090 error page</ulink>, the <ulink
8091 url="http://ads.bannerserver.example.com/nasty-ads/sponsor.html"><quote>BLOCKED</quote>
8093 and all pages of its <ulink url="http://config.privoxy.org/">web-based
8094 user interface</ulink>, are generated from <emphasis>templates</emphasis>.
8095 (<application>Privoxy</application> must be running for the above links to work as
8100 These templates are stored in a subdirectory of the <link linkend="confdir">configuration
8101 directory</link> called <filename>templates</filename>. On Unixish platforms,
8103 <ulink url="file:///etc/privoxy/templates/"><filename>/etc/privoxy/templates/</filename></ulink>.
8107 The templates are basically normal HTML files, but with place-holders (called symbols
8108 or exports), which <application>Privoxy</application> fills at run time. It
8109 is possible to edit the templates with a normal text editor, should you want
8110 to customize them. (<emphasis>Not recommended for the casual
8111 user</emphasis>). Should you create your own custom templates, you should use
8112 the <filename>config</filename> setting <link linkend="templdir">templdir</link>
8113 to specify an alternate location, so your templates do not get overwritten
8117 Note that just like in configuration files, lines starting
8118 with <literal>#</literal> are ignored when the templates are filled in.
8122 The place-holders are of the form <literal>@name@</literal>, and you will
8123 find a list of available symbols, which vary from template to template,
8124 in the comments at the start of each file. Note that these comments are not
8125 always accurate, and that it's probably best to look at the existing HTML
8126 code to find out which symbols are supported and what they are filled in with.
8130 A special application of this substitution mechanism is to make whole
8131 blocks of HTML code disappear when a specific symbol is set. We use this
8132 for many purposes, one of them being to include the beta warning in all
8133 our user interface (CGI) pages when <application>Privoxy</application>
8134 is in an alpha or beta development stage:
8138 <!-- @if-unstable-start -->
8140 ... beta warning HTML code goes here ...
8142 <!-- if-unstable-end@ --></screen>
8145 If the "unstable" symbol is set, everything in between and including
8146 <literal>@if-unstable-start</literal> and <literal>if-unstable-end@</literal>
8147 will disappear, leaving nothing but an empty comment:
8150 <screen><!-- --></screen>
8153 There's also an if-then-else construct and an <literal>#include</literal>
8154 mechanism, but you'll sure find out if you are inclined to edit the
8159 All templates refer to a style located at
8160 <ulink url="http://config.privoxy.org/send-stylesheet"><literal>http://config.privoxy.org/send-stylesheet</literal></ulink>.
8161 This is, of course, locally served by <application>Privoxy</application>
8162 and the source for it can be found and edited in the
8163 <filename>cgi-style.css</filename> template.
8168 <!-- ~ End section ~ -->
8172 <!-- ~~~~~ New section ~~~~~ -->
8174 <sect1 id="contact"><title>Contacting the Developers, Bug Reporting and Feature
8177 <!-- Include contacting.sgml boilerplate: -->
8179 <!-- end boilerplate -->
8183 <!-- ~ End section ~ -->
8186 <!-- ~~~~~ New section ~~~~~ -->
8187 <sect1 id="copyright"><title>Privoxy Copyright, License and History</title>
8189 <!-- Include copyright.sgml: -->
8191 <!-- end copyright -->
8194 <application>Privoxy</application> is free software; you can
8195 redistribute and/or modify its source code under the terms
8196 of the <citetitle>GNU General Public License</citetitle>
8197 as published by the Free Software Foundation, either version 2
8198 of the license, or (at your option) any later version.
8202 The same is true for <application>Privoxy</application> binaries
8203 unless they are linked with a
8204 <ulink url="https://www.trustedfirmware.org/projects/mbed-tls/">mbed TLS</ulink> version
8205 that is licensed under the Apache 2.0 license in which
8206 case you can redistribute and/or modify the <application>Privoxy</application>
8207 binaries under the terms of the <citetitle>GNU General Public License</citetitle>
8208 as published by the Free Software Foundation, either version 3
8209 of the license, or (at your option) any later version.
8213 Both licenses are included in the next section.
8216 <!-- ~~~~~ New section ~~~~~ -->
8217 <sect2 id="license"><title>License</title>
8219 <sect3 id="gplv2"><title>GNU General Public License version 2</title>
8220 <literallayout class="Monospaced"><![ RCDATA [ &GPLv2; ]]></literallayout>
8223 <sect3 id="gplv3"><title>GNU General Public License version 3</title>
8224 <literallayout class="Monospaced"><![ RCDATA [ &GPLv3; ]]></literallayout>
8227 <sect3 id="third-party-licenses"><title>Third-party licenses and copyrights</title>
8229 Privoxy depends on a couple of third-party libraries which have seperate licenses.
8230 Please refer to the third-party websites for up-to-date license and copyright
8234 Privoxy depends on <ulink url="https://pcre.org/">pcre</ulink>.
8237 When compiled with FEATURE_BROTLI (optional), Privoxy depends on
8238 <ulink url="https://www.brotli.org/">brotli</ulink>.
8241 When compiled with FEATURE_HTTPS_INSPECTION (optional),
8242 Privoxy depends on a TLS library. The supported libraries are
8243 <ulink url="https://www.openssl.org/">LibreSSL</ulink>,
8244 <ulink url="https://github.com/Mbed-TLS/mbedtls/tags">mbed TLS 2.28.x</ulink> and
8245 <ulink url="https://www.openssl.org/">OpenSSL</ulink>.
8248 When compiled with FEATURE_ZLIB (optional),
8249 Privoxy depends on <ulink url="https://zlib.net/">zlib</ulink>.
8254 <!-- ~ End section ~ -->
8257 <!-- ~~~~~ New section ~~~~~ -->
8259 <sect2 id="history"><title>History</title>
8260 <!-- Include history.sgml: -->
8262 <!-- end history -->
8265 <sect2 id="authors"><title>Authors</title>
8266 <!-- Include p-authors.sgml: -->
8268 <!-- end authors -->
8273 <!-- ~ End section ~ -->
8276 <!-- ~~~~~ New section ~~~~~ -->
8277 <sect1 id="seealso"><title>See Also</title>
8278 <!-- Include seealso.sgml: -->
8280 <!-- end seealso -->
8285 <!-- ~~~~~ New section ~~~~~ -->
8286 <sect1 id="appendix"><title>Appendix</title>
8289 <!-- ~~~~~ New section ~~~~~ -->
8291 <title>Regular Expressions</title>
8293 <application>Privoxy</application> uses Perl-style <quote>regular
8294 expressions</quote> in its <link linkend="actions-file">actions
8295 files</link> and <link linkend="filter-file">filter file</link>,
8296 through the <ulink url="http://www.pcre.org/">PCRE</ulink> and
8299 <ulink url="http://www.oesterhelt.org/pcrs/">PCRS</ulink> libraries.
8301 <application>PCRS</application> libraries.
8305 If you are reading this, you probably don't understand what <quote>regular
8306 expressions</quote> are, or what they can do. So this will be a very brief
8307 introduction only. A full explanation would require a <ulink
8308 url="http://www.oreilly.com/catalog/regex/">book</ulink> ;-)
8312 Regular expressions provide a language to describe patterns that can be
8313 run against strings of characters (letter, numbers, etc), to see if they
8314 match the string or not. The patterns are themselves (sometimes complex)
8315 strings of literal characters, combined with wild-cards, and other special
8316 characters, called meta-characters. The <quote>meta-characters</quote> have
8317 special meanings and are used to build complex patterns to be matched against.
8318 Perl Compatible Regular Expressions are an especially convenient
8319 <quote>dialect</quote> of the regular expression language.
8323 To make a simple analogy, we do something similar when we use wild-card
8324 characters when listing files with the <command>dir</command> command in DOS.
8325 <literal>*.*</literal> matches all filenames. The <quote>special</quote>
8326 character here is the asterisk which matches any and all characters. We can be
8327 more specific and use <literal>?</literal> to match just individual
8328 characters. So <quote>dir file?.text</quote> would match
8329 <quote>file1.txt</quote>, <quote>file2.txt</quote>, etc. We are pattern
8330 matching, using a similar technique to <quote>regular expressions</quote>!
8334 Regular expressions do essentially the same thing, but are much, much more
8335 powerful. There are many more <quote>special characters</quote> and ways of
8336 building complex patterns however. Let's look at a few of the common ones,
8337 and then some examples:
8342 <emphasis>.</emphasis> - Matches any single character, e.g. <quote>a</quote>,
8343 <quote>A</quote>, <quote>4</quote>, <quote>:</quote>, or <quote>@</quote>.
8349 <emphasis>?</emphasis> - The preceding character or expression is matched ZERO or ONE
8356 <emphasis>+</emphasis> - The preceding character or expression is matched ONE or MORE
8363 <emphasis>*</emphasis> - The preceding character or expression is matched ZERO or MORE
8370 <emphasis>\</emphasis> - The <quote>escape</quote> character denotes that
8371 the following character should be taken literally. This is used where one of the
8372 special characters (e.g. <quote>.</quote>) needs to be taken literally and
8373 not as a special meta-character. Example: <quote>example\.com</quote>, makes
8374 sure the period is recognized only as a period (and not expanded to its
8375 meta-character meaning of any single character).
8381 <emphasis>[ ]</emphasis> - Characters enclosed in brackets will be matched if
8382 any of the enclosed characters are encountered. For instance, <quote>[0-9]</quote>
8383 matches any numeric digit (zero through nine). As an example, we can combine
8384 this with <quote>+</quote> to match any digit one of more times: <quote>[0-9]+</quote>.
8390 <emphasis>( )</emphasis> - parentheses are used to group a sub-expression,
8391 or multiple sub-expressions.
8397 <emphasis>|</emphasis> - The <quote>bar</quote> character works like an
8398 <quote>or</quote> conditional statement. A match is successful if the
8399 sub-expression on either side of <quote>|</quote> matches. As an example:
8400 <quote>/(this|that) example/</quote> uses grouping and the bar character
8401 and would match either <quote>this example</quote> or <quote>that
8402 example</quote>, and nothing else.
8407 These are just some of the ones you are likely to use when matching URLs with
8408 <application>Privoxy</application>, and is a long way from a definitive
8409 list. This is enough to get us started with a few simple examples which may
8410 be more illuminating:
8414 <emphasis><literal>/.*/banners/.*</literal></emphasis> - A simple example
8415 that uses the common combination of <quote>.</quote> and <quote>*</quote> to
8416 denote any character, zero or more times. In other words, any string at all.
8417 So we start with a literal forward slash, then our regular expression pattern
8418 (<quote>.*</quote>) another literal forward slash, the string
8419 <quote>banners</quote>, another forward slash, and lastly another
8420 <quote>.*</quote>. We are building
8421 a directory path here. This will match any file with the path that has a
8422 directory named <quote>banners</quote> in it. The <quote>.*</quote> matches
8423 any characters, and this could conceivably be more forward slashes, so it
8424 might expand into a much longer looking path. For example, this could match:
8425 <quote>/eye/hate/spammers/banners/annoy_me_please.gif</quote>, or just
8426 <quote>/banners/annoying.html</quote>, or almost an infinite number of other
8427 possible combinations, just so it has <quote>banners</quote> in the path
8432 And now something a little more complex:
8436 <emphasis><literal>/.*/adv((er)?ts?|ertis(ing|ements?))?/</literal></emphasis> -
8437 We have several literal forward slashes again (<quote>/</quote>), so we are
8438 building another expression that is a file path statement. We have another
8439 <quote>.*</quote>, so we are matching against any conceivable sub-path, just so
8440 it matches our expression. The only true literal that <emphasis>must
8441 match</emphasis> our pattern is <application>adv</application>, together with
8442 the forward slashes. What comes after the <quote>adv</quote> string is the
8447 Remember the <quote>?</quote> means the preceding expression (either a
8448 literal character or anything grouped with <quote>(...)</quote> in this case)
8449 can exist or not, since this means either zero or one match. So
8450 <quote>((er)?ts?|ertis(ing|ements?))</quote> is optional, as are the
8451 individual sub-expressions: <quote>(er)</quote>,
8452 <quote>(ing|ements?)</quote>, and the <quote>s</quote>. The <quote>|</quote>
8453 means <quote>or</quote>. We have two of those. For instance,
8454 <quote>(ing|ements?)</quote>, can expand to match either <quote>ing</quote>
8455 <emphasis>OR</emphasis> <quote>ements?</quote>. What is being done here, is an
8456 attempt at matching as many variations of <quote>advertisement</quote>, and
8457 similar, as possible. So this would expand to match just <quote>adv</quote>,
8458 or <quote>advert</quote>, or <quote>adverts</quote>, or
8459 <quote>advertising</quote>, or <quote>advertisement</quote>, or
8460 <quote>advertisements</quote>. You get the idea. But it would not match
8461 <quote>advertizements</quote> (with a <quote>z</quote>). We could fix that by
8462 changing our regular expression to:
8463 <quote>/.*/adv((er)?ts?|erti(s|z)(ing|ements?))?/</quote>, which would then match
8468 <emphasis><literal>/.*/advert[0-9]+\.(gif|jpe?g)</literal></emphasis> - Again
8469 another path statement with forward slashes. Anything in the square brackets
8470 <quote>[ ]</quote> can be matched. This is using <quote>0-9</quote> as a
8471 shorthand expression to mean any digit one through nine. It is the same as
8472 saying <quote>0123456789</quote>. So any digit matches. The <quote>+</quote>
8473 means one or more of the preceding expression must be included. The preceding
8474 expression here is what is in the square brackets -- in this case, any digit
8475 one through nine. Then, at the end, we have a grouping: <quote>(gif|jpe?g)</quote>.
8476 This includes a <quote>|</quote>, so this needs to match the expression on
8477 either side of that bar character also. A simple <quote>gif</quote> on one side, and the other
8478 side will in turn match either <quote>jpeg</quote> or <quote>jpg</quote>,
8479 since the <quote>?</quote> means the letter <quote>e</quote> is optional and
8480 can be matched once or not at all. So we are building an expression here to
8481 match image GIF or JPEG type image file. It must include the literal
8482 string <quote>advert</quote>, then one or more digits, and a <quote>.</quote>
8483 (which is now a literal, and not a special character, since it is escaped
8484 with <quote>\</quote>), and lastly either <quote>gif</quote>, or
8485 <quote>jpeg</quote>, or <quote>jpg</quote>. Some possible matches would
8486 include: <quote>//advert1.jpg</quote>,
8487 <quote>/nasty/ads/advert1234.gif</quote>,
8488 <quote>/banners/from/hell/advert99.jpg</quote>. It would not match
8489 <quote>advert1.gif</quote> (no leading slash), or
8490 <quote>/adverts232.jpg</quote> (the expression does not include an
8491 <quote>s</quote>), or <quote>/advert1.jsp</quote> (<quote>jsp</quote> is not
8492 in the expression anywhere).
8496 We are barely scratching the surface of regular expressions here so that you
8497 can understand the default <application>Privoxy</application>
8498 configuration files, and maybe use this knowledge to customize your own
8499 installation. There is much, much more that can be done with regular
8500 expressions. Now that you know enough to get started, you can learn more on
8505 More reading on Perl Compatible Regular expressions:
8506 <ulink url="http://perldoc.perl.org/perlre.html">http://perldoc.perl.org/perlre.html</ulink>
8510 For information on regular expression based substitutions and their applications
8511 in filters, please see the <link linkend="filter-file">filter file tutorial</link>
8516 <!-- ~ End section ~ -->
8519 <!-- ~~~~~ New section ~~~~~ -->
8520 <sect2 id="internal-pages">
8521 <title>Privoxy's Internal Pages</title>
8524 Since <application>Privoxy</application> proxies each requested
8525 web page, it is easy for <application>Privoxy</application> to
8526 trap certain special URLs. In this way, we can talk directly to
8527 <application>Privoxy</application>, and see how it is
8528 configured, see how our rules are being applied, change these
8529 rules and other configuration options, and even turn
8530 <application>Privoxy's</application> filtering off, all with
8535 The URLs listed below are the special ones that allow direct access
8536 to <application>Privoxy</application>. Of course,
8537 <application>Privoxy</application> must be running to access these. If
8538 not, you will get a friendly error message. Internet access is not
8550 <ulink url="http://config.privoxy.org/">http://config.privoxy.org/</ulink>
8554 There is a shortcut: <ulink url="http://p.p/">http://p.p/</ulink> (But it
8555 doesn't provide a fall-back to a real page, in case the request is not
8556 sent through <application>Privoxy</application>)
8562 View and toggle client tags:
8566 <ulink url="http://config.privoxy.org/client-tags">http://config.privoxy.org/client-tags</ulink>
8573 Show information about the current configuration, including viewing and
8574 editing of actions files:
8578 <ulink url="http://config.privoxy.org/show-status">http://config.privoxy.org/show-status</ulink>
8585 Show the browser's request headers:
8589 <ulink url="http://config.privoxy.org/show-request">http://config.privoxy.org/show-request</ulink>
8596 Show which actions apply to a URL and why:
8600 <ulink url="http://config.privoxy.org/show-url-info">http://config.privoxy.org/show-url-info</ulink>
8607 Toggle Privoxy on or off. This feature can be turned off/on in the main
8608 <filename>config</filename> file. When toggled <quote>off</quote>, <quote>Privoxy</quote>
8609 continues to run, but only as a pass-through proxy, with no actions taking
8614 <ulink url="http://config.privoxy.org/toggle">http://config.privoxy.org/toggle</ulink>
8618 Short cuts. Turn off, then on:
8622 <ulink url="http://config.privoxy.org/toggle?set=disable">http://config.privoxy.org/toggle?set=disable</ulink>
8627 <ulink url="http://config.privoxy.org/toggle?set=enable">http://config.privoxy.org/toggle?set=enable</ulink>
8637 <!-- ~~~~~ New section ~~~~~ -->
8639 <title>Chain of Events</title>
8641 Let's take a quick look at how some of <application>Privoxy's</application>
8642 core features are triggered, and the ensuing sequence of events when a web
8643 page is requested by your browser:
8649 First, your web browser requests a web page. The browser knows to send
8650 the request to <application>Privoxy</application>, which will in turn,
8651 relay the request to the remote web server after passing the following
8657 <application>Privoxy</application> traps any request for its own internal CGI
8658 pages (e.g <ulink url="http://p.p/">http://p.p/</ulink>) and sends the CGI page back to the browser.
8663 Next, <application>Privoxy</application> checks to see if the URL
8665 linkend="BLOCK"><quote>+block</quote></link> patterns. If
8666 so, the URL is then blocked, and the remote web server will not be contacted.
8667 <link linkend="HANDLE-AS-IMAGE"><quote>+handle-as-image</quote></link>
8669 <link linkend="HANDLE-AS-EMPTY-DOCUMENT"><quote>+handle-as-empty-document</quote></link>
8670 are then checked, and if there is no match, an
8671 HTML <quote>BLOCKED</quote> page is sent back to the browser. Otherwise, if
8672 it does match, an image is returned for the former, and an empty text
8673 document for the latter. The type of image would depend on the setting of
8674 <link linkend="SET-IMAGE-BLOCKER"><quote>+set-image-blocker</quote></link>
8675 (blank, checkerboard pattern, or an HTTP redirect to an image elsewhere).
8680 Untrusted URLs are blocked. If URLs are being added to the
8681 <filename>trust</filename> file, then that is done.
8686 If the URL pattern matches the <link
8687 linkend="FAST-REDIRECTS"><quote>+fast-redirects</quote></link> action,
8688 it is then processed. Unwanted parts of the requested URL are stripped.
8693 Now the rest of the client browser's request headers are processed. If any
8694 of these match any of the relevant actions (e.g. <link
8695 linkend="HIDE-USER-AGENT"><quote>+hide-user-agent</quote></link>,
8696 etc.), headers are suppressed or forged as determined by these actions and
8702 Now the web server starts sending its response back (i.e. typically a web
8708 First, the server headers are read and processed to determine, among other
8709 things, the MIME type (document type) and encoding. The headers are then
8710 filtered as determined by the
8711 <link linkend="CRUNCH-INCOMING-COOKIES"><quote>+crunch-incoming-cookies</quote></link>,
8712 <link linkend="SESSION-COOKIES-ONLY"><quote>+session-cookies-only</quote></link>,
8713 and <link linkend="DOWNGRADE-HTTP-VERSION"><quote>+downgrade-http-version</quote></link>
8719 If any <link linkend="FILTER"><quote>+filter</quote></link> action
8721 linkend="DEANIMATE-GIFS"><quote>+deanimate-gifs</quote></link>
8722 action applies (and the document type fits the action), the rest of the page is
8723 read into memory (up to a configurable limit). Then the filter rules (from
8724 <filename>default.filter</filename> and any other filter files) are
8725 processed against the buffered content. Filters are applied in the order
8726 they are specified in one of the filter files. Animated GIFs, if present,
8727 are reduced to either the first or last frame, depending on the action
8728 setting.The entire page, which is now filtered, is then sent by
8729 <application>Privoxy</application> back to your browser.
8732 If neither a <link linkend="FILTER"><quote>+filter</quote></link> action
8734 linkend="DEANIMATE-GIFS"><quote>+deanimate-gifs</quote></link>
8735 matches, then <application>Privoxy</application> passes the raw data through
8736 to the client browser as it becomes available.
8741 As the browser receives the now (possibly filtered) page content, it
8742 reads and then requests any URLs that may be embedded within the page
8743 source, e.g. ad images, stylesheets, JavaScript, other HTML documents (e.g.
8744 frames), sounds, etc. For each of these objects, the browser issues a
8745 separate request (this is easily viewable in <application>Privoxy's</application>
8746 logs). And each such request is in turn processed just as above. Note that a
8747 complex web page will have many, many such embedded URLs. If these
8748 secondary requests are to a different server, then quite possibly a very
8749 differing set of actions is triggered.
8756 NOTE: This is somewhat of a simplistic overview of what happens with each URL
8757 request. For the sake of brevity and simplicity, we have focused on
8758 <application>Privoxy's</application> core features only.
8764 <!-- ~~~~~ New section ~~~~~ -->
8765 <sect2 id="actionsanat">
8766 <title>Troubleshooting: Anatomy of an Action</title>
8769 The way <application>Privoxy</application> applies
8770 <link linkend="ACTIONS">actions</link> and <link linkend="FILTER">filters</link>
8771 to any given URL can be complex, and not always so
8772 easy to understand what is happening. And sometimes we need to be able to
8773 <emphasis>see</emphasis> just what <application>Privoxy</application> is
8774 doing. Especially, if something <application>Privoxy</application> is doing
8775 is causing us a problem inadvertently. It can be a little daunting to look at
8776 the actions and filters files themselves, since they tend to be filled with
8777 <link linkend="regex">regular expressions</link> whose consequences are not
8782 One quick test to see if <application>Privoxy</application> is causing a problem
8783 or not, is to disable it temporarily. This should be the first troubleshooting
8784 step (be sure to flush caches afterward!). Looking at the
8785 logs is a good idea too. (Note that both the toggle feature and logging are
8786 enabled via <filename>config</filename> file settings, and may need to be
8787 turned <quote>on</quote>.)
8790 Another easy troubleshooting step to try is if you have done any
8791 customization of your installation, revert back to the installed
8792 defaults and see if that helps. There are times the developers get complaints
8793 about one thing or another, and the problem is more related to a customized
8794 configuration issue.
8798 <application>Privoxy</application> also provides the
8799 <ulink url="http://config.privoxy.org/show-url-info">http://config.privoxy.org/show-url-info</ulink>
8800 page that can show us very specifically how <application>actions</application>
8801 are being applied to any given URL. This is a big help for troubleshooting.
8805 First, enter one URL (or partial URL) at the prompt, and then
8806 <application>Privoxy</application> will tell us
8807 how the current configuration will handle it. This will not
8808 help with filtering effects (i.e. the <link
8809 linkend="FILTER"><quote>+filter</quote></link> action) from
8810 one of the filter files since this is handled very
8811 differently and not so easy to trap! It also will not tell you about any other
8812 URLs that may be embedded within the URL you are testing. For instance, images
8813 such as ads are expressed as URLs within the raw page source of HTML pages. So
8814 you will only get info for the actual URL that is pasted into the prompt area
8815 -- not any sub-URLs. If you want to know about embedded URLs like ads, you
8816 will have to dig those out of the HTML source. Use your browser's <quote>View
8817 Page Source</quote> option for this. Or right click on the ad, and grab the
8822 Let's try an example, <ulink url="http://google.com">google.com</ulink>,
8823 and look at it one section at a time in a sample configuration (your real
8824 configuration may vary):
8828 Matches for http://www.google.com:
8830 In file: default.action <guibutton>[ View ]</guibutton> <guibutton>[ Edit ]</guibutton>
8832 {+change-x-forwarded-for{block}
8833 +deanimate-gifs {last}
8834 +fast-redirects {check-decoded-url}
8835 +filter {refresh-tags}
8836 +filter {img-reorder}
8837 +filter {banners-by-size}
8839 +filter {jumping-windows}
8840 +filter {ie-exploits}
8841 +hide-from-header {block}
8842 +hide-referrer {forge}
8843 +session-cookies-only
8844 +set-image-blocker {pattern} }
8847 { -session-cookies-only }
8853 In file: user.action <guibutton>[ View ]</guibutton> <guibutton>[ Edit ]</guibutton>
8854 (no matches in this file)
8858 This is telling us how we have defined our
8859 <link linkend="ACTIONS"><quote>actions</quote></link>, and
8860 which ones match for our test case, <quote>google.com</quote>.
8861 Displayed is all the actions that are available to us. Remember,
8862 the <literal>+</literal> sign denotes <quote>on</quote>. <literal>-</literal>
8863 denotes <quote>off</quote>. So some are <quote>on</quote> here, but many
8864 are <quote>off</quote>. Each example we try may provide a slightly different
8865 end result, depending on our configuration directives.
8869 is for our <filename>default.action</filename> file. The large, multi-line
8870 listing, is how the actions are set to match for all URLs, i.e. our default
8871 settings. If you look at your <quote>actions</quote> file, this would be the
8872 section just below the <quote>aliases</quote> section near the top. This
8873 will apply to all URLs as signified by the single forward slash at the end
8874 of the listing -- <quote> / </quote>.
8878 But we have defined additional actions that would be exceptions to these general
8879 rules, and then we list specific URLs (or patterns) that these exceptions
8880 would apply to. Last match wins. Just below this then are two explicit
8881 matches for <quote>.google.com</quote>. The first is negating our previous
8882 cookie setting, which was for <link
8883 linkend="SESSION-COOKIES-ONLY"><quote>+session-cookies-only</quote></link>
8884 (i.e. not persistent). So we will allow persistent cookies for google, at
8885 least that is how it is in this example. The second turns
8886 <emphasis>off</emphasis> any <link
8887 linkend="FAST-REDIRECTS"><quote>+fast-redirects</quote></link>
8888 action, allowing this to take place unmolested. Note that there is a leading
8889 dot here -- <quote>.google.com</quote>. This will match any hosts and
8890 sub-domains, in the google.com domain also, such as
8891 <quote>www.google.com</quote> or <quote>mail.google.com</quote>. But it would not
8892 match <quote>www.google.de</quote>! So, apparently, we have these two actions
8893 defined as exceptions to the general rules at the top somewhere in the lower
8894 part of our <filename>default.action</filename> file, and
8895 <quote>google.com</quote> is referenced somewhere in these latter sections.
8899 Then, for our <filename>user.action</filename> file, we again have no hits.
8900 So there is nothing google-specific that we might have added to our own, local
8901 configuration. If there was, those actions would over-rule any actions from
8902 previously processed files, such as <filename>default.action</filename>.
8903 <filename>user.action</filename> typically has the last word. This is the
8904 best place to put hard and fast exceptions,
8908 And finally we pull it all together in the bottom section and summarize how
8909 <application>Privoxy</application> is applying all its <quote>actions</quote>
8910 to <quote>google.com</quote>:
8918 +change-x-forwarded-for{block}
8919 -client-header-filter{hide-tor-exit-notation}
8920 -content-type-overwrite
8921 -crunch-client-header
8922 -crunch-if-none-match
8923 -crunch-incoming-cookies
8924 -crunch-outgoing-cookies
8925 -crunch-server-header
8926 +deanimate-gifs {last}
8927 -downgrade-http-version
8930 -filter {content-cookies}
8931 -filter {all-popups}
8932 -filter {banners-by-link}
8933 -filter {tiny-textforms}
8934 -filter {frameset-borders}
8935 -filter {demoronizer}
8936 -filter {shockwave-flash}
8937 -filter {quicktime-kioskmode}
8939 -filter {crude-parental}
8940 -filter {site-specifics}
8941 -filter {js-annoyances}
8942 -filter {html-annoyances}
8943 +filter {refresh-tags}
8944 -filter {unsolicited-popups}
8945 +filter {img-reorder}
8946 +filter {banners-by-size}
8948 +filter {jumping-windows}
8949 +filter {ie-exploits}
8956 -handle-as-empty-document
8958 -hide-accept-language
8959 -hide-content-disposition
8960 +hide-from-header {block}
8961 -hide-if-modified-since
8962 +hide-referrer {forge}
8965 -overwrite-last-modified
8966 -prevent-compression
8968 -server-header-filter{xml-to-html}
8969 -server-header-filter{html-to-xml}
8970 -session-cookies-only
8971 +set-image-blocker {pattern}
8975 Notice the only difference here to the previous listing, is to
8976 <quote>fast-redirects</quote> and <quote>session-cookies-only</quote>,
8977 which are activated specifically for this site in our configuration,
8978 and thus show in the <quote>Final Results</quote>.
8982 Now another example, <quote>ad.doubleclick.net</quote>:
8986 { +block{Domains starts with "ad"} }
8989 { +block{Domain contains "ad"} }
8992 { +block{Doubleclick banner server} +handle-as-image }
8993 .[a-vx-z]*.doubleclick.net
8997 We'll just show the interesting part here - the explicit matches. It is
8998 matched three different times. Two <quote>+block{}</quote> sections,
8999 and a <quote>+block{} +handle-as-image</quote>,
9000 which is the expanded form of one of our aliases that had been defined as:
9001 <quote>+block-as-image</quote>. (<link
9002 linkend="ALIASES"><quote>Aliases</quote></link> are defined in
9003 the first section of the actions file and typically used to combine more
9008 Any one of these would have done the trick and blocked this as an unwanted
9009 image. This is unnecessarily redundant since the last case effectively
9010 would also cover the first. No point in taking chances with these guys
9011 though ;-) Note that if you want an ad or obnoxious
9012 URL to be invisible, it should be defined as <quote>ad.doubleclick.net</quote>
9013 is done here -- as both a <link
9014 linkend="BLOCK"><quote>+block{}</quote></link>
9015 <emphasis>and</emphasis> an
9016 <link linkend="HANDLE-AS-IMAGE"><quote>+handle-as-image</quote></link>.
9017 The custom alias <quote><literal>+block-as-image</literal></quote> just
9018 simplifies the process and make it more readable.
9022 One last example. Let's try <quote>http://www.example.net/adsl/HOWTO/</quote>.
9023 This one is giving us problems. We are getting a blank page. Hmmm ...
9027 Matches for http://www.example.net/adsl/HOWTO/:
9029 In file: default.action <guibutton>[ View ]</guibutton> <guibutton>[ Edit ]</guibutton>
9033 +change-x-forwarded-for{block}
9034 -client-header-filter{hide-tor-exit-notation}
9035 -content-type-overwrite
9036 -crunch-client-header
9037 -crunch-if-none-match
9038 -crunch-incoming-cookies
9039 -crunch-outgoing-cookies
9040 -crunch-server-header
9042 -downgrade-http-version
9043 +fast-redirects {check-decoded-url}
9045 -filter {content-cookies}
9046 -filter {all-popups}
9047 -filter {banners-by-link}
9048 -filter {tiny-textforms}
9049 -filter {frameset-borders}
9050 -filter {demoronizer}
9051 -filter {shockwave-flash}
9052 -filter {quicktime-kioskmode}
9054 -filter {crude-parental}
9055 -filter {site-specifics}
9056 -filter {js-annoyances}
9057 -filter {html-annoyances}
9058 +filter {refresh-tags}
9059 -filter {unsolicited-popups}
9060 +filter {img-reorder}
9061 +filter {banners-by-size}
9063 +filter {jumping-windows}
9064 +filter {ie-exploits}
9071 -handle-as-empty-document
9073 -hide-accept-language
9074 -hide-content-disposition
9075 +hide-from-header{block}
9076 +hide-referer{forge}
9078 -overwrite-last-modified
9079 +prevent-compression
9081 -server-header-filter{xml-to-html}
9082 -server-header-filter{html-to-xml}
9083 +session-cookies-only
9084 +set-image-blocker{blank} }
9087 { +block{Path contains "ads".} +handle-as-image }
9092 Ooops, the <quote>/adsl/</quote> is matching <quote>/ads</quote> in our
9093 configuration! But we did not want this at all! Now we see why we get the
9094 blank page. It is actually triggering two different actions here, and
9095 the effects are aggregated so that the URL is blocked, and &my-app; is told
9096 to treat the block as if it were an image. But this is, of course, all wrong.
9097 We could now add a new action below this (or better in our own
9098 <filename>user.action</filename> file) that explicitly
9099 <emphasis>un</emphasis> blocks (
9100 <link linkend="BLOCK"><quote>{-block}</quote></link>) paths with
9101 <quote>adsl</quote> in them (remember, last match in the configuration
9102 wins). There are various ways to handle such exceptions. Example:
9111 Now the page displays ;-)
9112 Remember to flush your browser's caches when making these kinds of changes to
9113 your configuration to insure that you get a freshly delivered page! Or, try
9114 using <literal>Shift+Reload</literal>.
9118 But now what about a situation where we get no explicit matches like
9123 { +block{Path starts with "ads".} +handle-as-image }
9128 That actually was very helpful and pointed us quickly to where the problem
9129 was. If you don't get this kind of match, then it means one of the default
9130 rules in the first section of <filename>default.action</filename> is causing
9131 the problem. This would require some guesswork, and maybe a little trial and
9132 error to isolate the offending rule. One likely cause would be one of the
9133 <link linkend="FILTER"><quote>+filter</quote></link> actions.
9134 These tend to be harder to troubleshoot.
9135 Try adding the URL for the site to one of aliases that turn off
9136 <link linkend="FILTER"><quote>+filter</quote></link>:
9142 .worldpay.com # for quietpc.com
9149 <quote><literal>{ shop }</literal></quote> is an <quote>alias</quote> that expands to
9150 <quote><literal>{ -filter -session-cookies-only }</literal></quote>.
9151 Or you could do your own exception to negate filtering:
9156 # Disable ALL filter actions for sites in this section
9163 This would turn off all filtering for these sites. This is best
9164 put in <filename>user.action</filename>, for local site
9165 exceptions. Note that when a simple domain pattern is used by itself (without
9166 the subsequent path portion), all sub-pages within that domain are included
9167 automatically in the scope of the action.
9171 Images that are inexplicably being blocked, may well be hitting the
9172 <link linkend="FILTER-BANNERS-BY-SIZE"><quote>+filter{banners-by-size}</quote></link>
9174 that images of certain sizes are ad banners (works well
9175 <emphasis>most of the time</emphasis> since these tend to be standardized).
9179 <quote><literal>{ fragile }</literal></quote> is an alias that disables most
9180 actions that are the most likely to cause trouble. This can be used as a
9181 last resort for problem sites.
9186 # Handle with care: easy to break
9193 <emphasis>Remember to flush caches!</emphasis> Note that the
9194 <literal>mail.google</literal> reference lacks the TLD portion (e.g.
9195 <quote>.com</quote>). This will effectively match any TLD with
9196 <literal>google</literal> in it, such as <literal>mail.google.de.</literal>,
9200 If this still does not work, you will have to go through the remaining
9201 actions one by one to find which one(s) is causing the problem.
9210 This program is free software; you can redistribute it
9211 and/or modify it under the terms of the GNU General
9212 Public License as published by the Free Software
9213 Foundation; either version 2 of the License, or (at
9214 your option) any later version.
9216 This program is distributed in the hope that it will
9217 be useful, but WITHOUT ANY WARRANTY; without even the
9218 implied warranty of MERCHANTABILITY or FITNESS FOR A
9219 PARTICULAR PURPOSE. See the GNU General Public
9220 License for more details.
9222 The GNU General Public License should be included with
9223 this file. If not, you can view it at
9224 http://www.gnu.org/copyleft/gpl.html
9225 or write to the Free Software Foundation, Inc.,
9226 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,