+++ /dev/null
- Privoxy 3.0.8 User Manual
-
- [Copyright[ (c) 2001 - 2008 by Privoxy Developers]]
-
- $Id: user-manual.txt,v 1.75 2008/01/20 08:42:48 fabiankeil Exp $
-
- The Privoxy User Manual gives users information on how to install,
- configure and use Privoxy.
-
- Privoxy is a non-caching web proxy with advanced filtering capabilities
- for enhancing privacy, modifying web page data, managing HTTP cookies,
- controlling access, and removing ads, banners, pop-ups and other obnoxious
- Internet junk. Privoxy has a flexible configuration and can be customized
- to suit individual needs and tastes. Privoxy has application for both
- stand-alone systems and multi-user networks.
-
- Privoxy is based on Internet Junkbuster (tm).
-
- You can find the latest version of the Privoxy User Manual at
- http://www.privoxy.org/user-manual/. Please see the Contact section on how
- to contact the developers.
-
- --------------------------------------------------------------------------
-
- Table of Contents
-
- 1. Introduction
-
- 1.1. Features
-
- 2. Installation
-
- 2.1. Binary Packages
-
- 2.1.1. Red Hat and Fedora RPMs
-
- 2.1.2. Debian and Ubuntu
-
- 2.1.3. Windows
-
- 2.1.4. Solaris
-
- 2.1.5. OS/2
-
- 2.1.6. Mac OSX
-
- 2.1.7. AmigaOS
-
- 2.1.8. FreeBSD
-
- 2.1.9. Gentoo
-
- 2.2. Building from Source
-
- 2.3. Keeping your Installation Up-to-Date
-
- 3. What's New in this Release
-
- 3.1. Note to Upgraders
-
- 4. Quickstart to Using Privoxy
-
- 4.1. Quickstart to Ad Blocking
-
- 5. Starting Privoxy
-
- 5.1. Red Hat and Fedora
-
- 5.2. Debian
-
- 5.3. Windows
-
- 5.4. Solaris, NetBSD, FreeBSD, HP-UX and others
-
- 5.5. OS/2
-
- 5.6. Mac OSX
-
- 5.7. AmigaOS
-
- 5.8. Gentoo
-
- 5.9. Command Line Options
-
- 6. Privoxy Configuration
-
- 6.1. Controlling Privoxy with Your Web Browser
-
- 6.2. Configuration Files Overview
-
- 7. The Main Configuration File
-
- 7.1. Local Set-up Documentation
-
- 7.1.1. user-manual
-
- 7.1.2. trust-info-url
-
- 7.1.3. admin-address
-
- 7.1.4. proxy-info-url
-
- 7.2. Configuration and Log File Locations
-
- 7.2.1. confdir
-
- 7.2.2. templdir
-
- 7.2.3. logdir
-
- 7.2.4. actionsfile
-
- 7.2.5. filterfile
-
- 7.2.6. logfile
-
- 7.2.7. jarfile
-
- 7.2.8. trustfile
-
- 7.3. Debugging
-
- 7.3.1. debug
-
- 7.3.2. single-threaded
-
- 7.4. Access Control and Security
-
- 7.4.1. listen-address
-
- 7.4.2. toggle
-
- 7.4.3. enable-remote-toggle
-
- 7.4.4. enable-remote-http-toggle
-
- 7.4.5. enable-edit-actions
-
- 7.4.6. enforce-blocks
-
- 7.4.7. ACLs: permit-access and deny-access
-
- 7.4.8. buffer-limit
-
- 7.5. Forwarding
-
- 7.5.1. forward
-
- 7.5.2. forward-socks4 and forward-socks4a
-
- 7.5.3. Advanced Forwarding Examples
-
- 7.5.4. forwarded-connect-retries
-
- 7.5.5. accept-intercepted-requests
-
- 7.5.6. allow-cgi-request-crunching
-
- 7.5.7. split-large-forms
-
- 7.6. Windows GUI Options
-
- 8. Actions Files
-
- 8.1. Finding the Right Mix
-
- 8.2. How to Edit
-
- 8.3. How Actions are Applied to Requests
-
- 8.4. Patterns
-
- 8.4.1. The Domain Pattern
-
- 8.4.2. The Path Pattern
-
- 8.4.3. The Tag Pattern
-
- 8.5. Actions
-
- 8.5.1. add-header
-
- 8.5.2. block
-
- 8.5.3. client-header-filter
-
- 8.5.4. client-header-tagger
-
- 8.5.5. content-type-overwrite
-
- 8.5.6. crunch-client-header
-
- 8.5.7. crunch-if-none-match
-
- 8.5.8. crunch-incoming-cookies
-
- 8.5.9. crunch-server-header
-
- 8.5.10. crunch-outgoing-cookies
-
- 8.5.11. deanimate-gifs
-
- 8.5.12. downgrade-http-version
-
- 8.5.13. fast-redirects
-
- 8.5.14. filter
-
- 8.5.15. force-text-mode
-
- 8.5.16. forward-override
-
- 8.5.17. handle-as-empty-document
-
- 8.5.18. handle-as-image
-
- 8.5.19. hide-accept-language
-
- 8.5.20. hide-content-disposition
-
- 8.5.21. hide-if-modified-since
-
- 8.5.22. hide-forwarded-for-headers
-
- 8.5.23. hide-from-header
-
- 8.5.24. hide-referrer
-
- 8.5.25. hide-user-agent
-
- 8.5.26. inspect-jpegs
-
- 8.5.27. kill-popups
-
- 8.5.28. limit-connect
-
- 8.5.29. prevent-compression
-
- 8.5.30. overwrite-last-modified
-
- 8.5.31. redirect
-
- 8.5.32. send-vanilla-wafer
-
- 8.5.33. send-wafer
-
- 8.5.34. server-header-filter
-
- 8.5.35. server-header-tagger
-
- 8.5.36. session-cookies-only
-
- 8.5.37. set-image-blocker
-
- 8.5.38. treat-forbidden-connects-like-blocks
-
- 8.5.39. Summary
-
- 8.6. Aliases
-
- 8.7. Actions Files Tutorial
-
- 8.7.1. default.action
-
- 8.7.2. user.action
-
- 9. Filter Files
-
- 9.1. Filter File Tutorial
-
- 9.2. The Pre-defined Filters
-
- 10. Privoxy's Template Files
-
- 11. Contacting the Developers, Bug Reporting and Feature Requests
-
- 11.1. Get Support
-
- 11.2. Reporting Problems
-
- 11.2.1. Reporting Ads or Other Configuration
- Problems
-
- 11.2.2. Reporting Bugs
-
- 11.3. Request New Features
-
- 11.4. Other
-
- 12. Privoxy Copyright, License and History
-
- 12.1. License
-
- 12.2. History
-
- 12.3. Authors
-
- 13. See Also
-
- 14. Appendix
-
- 14.1. Regular Expressions
-
- 14.2. Privoxy's Internal Pages
-
- 14.2.1. Bookmarklets
-
- 14.3. Chain of Events
-
- 14.4. Troubleshooting: Anatomy of an Action
-
-1. Introduction
-
- This documentation is included with the current stable version of Privoxy,
- v.3.0.8.
-
- --------------------------------------------------------------------------
-
- 1.1. Features
-
- In addition to the core features of ad blocking and cookie management,
- Privoxy provides many supplemental features, that give the end-user more
- control, more privacy and more freedom:
-
- * Can be run as an "intercepting" proxy, which obviates the need to
- configure browsers individually.
-
- * Sophisticated actions and filters for manipulating both server and
- client headers.
-
- * Can be chained with other proxies.
-
- * Integrated browser based configuration and control utility at
- http://config.privoxy.org/ (shortcut: http://p.p/). Browser-based
- tracing of rule and filter effects. Remote toggling.
-
- * Web page filtering (text replacements, removes banners based on size,
- invisible "web-bugs", JavaScript and HTML annoyances, pop-up windows,
- etc.)
-
- * Modularized configuration that allows for standard settings and user
- settings to reside in separate files, so that installing updated
- actions files won't overwrite individual user settings.
-
- * Support for Perl Compatible Regular Expressions in the configuration
- files, and a more sophisticated and flexible configuration syntax.
-
- * Improved cookie management features (e.g. session based cookies).
-
- * GIF de-animation.
-
- * Bypass many click-tracking scripts (avoids script redirection).
-
- * Multi-threaded (POSIX and native threads).
-
- * User-customizable HTML templates for all proxy-generated pages (e.g.
- "blocked" page).
-
- * Auto-detection and re-reading of config file changes.
-
- * Improved signal handling, and a true daemon mode (Unix).
-
- * Every feature now controllable on a per-site or per-location basis,
- configuration more powerful and versatile over-all.
-
- * Many smaller new features added, limitations and bugs removed, and
- security holes fixed.
-
- --------------------------------------------------------------------------
-
-2. Installation
-
- Privoxy is available both in convenient pre-compiled packages for a wide
- range of operating systems, and as raw source code. For most users, we
- recommend using the packages, which can be downloaded from our Privoxy
- Project Page.
-
- Note: On some platforms, the installer may remove previously installed
- versions, if found. (See below for your platform). In any case be sure to
- backup your old configuration if it is valuable to you. See the note to
- upgraders section below.
-
- --------------------------------------------------------------------------
-
- 2.1. Binary Packages
-
- How to install the binary packages depends on your operating system:
-
- --------------------------------------------------------------------------
-
- 2.1.1. Red Hat and Fedora RPMs
-
- RPMs can be installed with rpm -Uvh privoxy-3.0.8-1.rpm, and will use
- /etc/privoxy for the location of configuration files.
-
- Note that on Red Hat, Privoxy will not be automatically started on system
- boot. You will need to enable that using chkconfig, ntsysv, or similar
- methods.
-
- If you have problems with failed dependencies, try rebuilding the SRC RPM:
- rpm --rebuild privoxy-3.0.8-1.src.rpm. This will use your locally
- installed libraries and RPM version.
-
- Also note that if you have a Junkbuster RPM installed on your system, you
- need to remove it first, because the packages conflict. Otherwise, RPM
- will try to remove Junkbuster automatically if found, before installing
- Privoxy.
-
- --------------------------------------------------------------------------
-
- 2.1.2. Debian and Ubuntu
-
- DEBs can be installed with apt-get install privoxy, and will use
- /etc/privoxy for the location of configuration files.
-
- --------------------------------------------------------------------------
-
- 2.1.3. Windows
-
- Just double-click the installer, which will guide you through the
- installation process. You will find the configuration files in the same
- directory as you installed Privoxy in.
-
- Version 3.0.5 beta introduced full Windows service functionality. On
- Windows only, the Privoxy program has two new command line arguments to
- install and uninstall Privoxy as a service.
-
- Arguments:
-
- --install[:service_name]
-
- --uninstall[:service_name]
-
- After invoking Privoxy with --install, you will need to bring up the
- Windows service console to assign the user you want Privoxy to run under,
- and whether or not you want it to run whenever the system starts. You can
- start the Windows services console with the following command:
- services.msc. If you do not take the manual step of modifying Privoxy's
- service settings, it will not start. Note too that you will need to give
- Privoxy a user account that actually exists, or it will not be permitted
- to write to its log and configuration files.
-
- --------------------------------------------------------------------------
-
- 2.1.4. Solaris
-
- Create a new directory, cd to it, then unzip and untar the archive. For
- the most part, you'll have to figure out where things go.
-
- --------------------------------------------------------------------------
-
- 2.1.5. OS/2
-
- First, make sure that no previous installations of Junkbuster and / or
- Privoxy are left on your system. Check that no Junkbuster or Privoxy
- objects are in your startup folder.
-
- Then, just double-click the WarpIN self-installing archive, which will
- guide you through the installation process. A shadow of the Privoxy
- executable will be placed in your startup folder so it will start
- automatically whenever OS/2 starts.
-
- The directory you choose to install Privoxy into will contain all of the
- configuration files.
-
- --------------------------------------------------------------------------
-
- 2.1.6. Mac OSX
-
- Unzip the downloaded file (you can either double-click on the file from
- the finder, or from the desktop if you downloaded it there). Then,
- double-click on the package installer icon named Privoxy.pkg and follow
- the installation process. Privoxy will be installed in the folder
- /Library/Privoxy. It will start automatically whenever you start up. To
- prevent it from starting automatically, remove or rename the folder
- /Library/StartupItems/Privoxy.
-
- To start Privoxy by hand, double-click on StartPrivoxy.command in the
- /Library/Privoxy folder. Or, type this command in the Terminal:
-
- /Library/Privoxy/StartPrivoxy.command
-
-
- You will be prompted for the administrator password.
-
- --------------------------------------------------------------------------
-
- 2.1.7. AmigaOS
-
- Copy and then unpack the lha archive to a suitable location. All necessary
- files will be installed into Privoxy directory, including all
- configuration and log files. To uninstall, just remove this directory.
-
- --------------------------------------------------------------------------
-
- 2.1.8. FreeBSD
-
- Privoxy is part of FreeBSD's Ports Collection, you can build and install
- it with cd /usr/ports/www/privoxy; make install clean.
-
- If you don't use the ports, you can fetch and install the package with
- pkg_add -r privoxy.
-
- The port skeleton and the package can also be downloaded from the File
- Release Page, but there's no reason to use them unless you're interested
- in the beta releases which are only available there.
-
- --------------------------------------------------------------------------
-
- 2.1.9. Gentoo
-
- Gentoo source packages (Ebuilds) for Privoxy are contained in the Gentoo
- Portage Tree (they are not on the download page, but there is a Gentoo
- section, where you can see when a new Privoxy Version is added to the
- Portage Tree).
-
- Before installing Privoxy under Gentoo just do first emerge rsync to get
- the latest changes from the Portage tree. With emerge privoxy you install
- the latest version.
-
- Configuration files are in /etc/privoxy, the documentation is in
- /usr/share/doc/privoxy-3.0.8 and the Log directory is in /var/log/privoxy.
-
- --------------------------------------------------------------------------
-
- 2.2. Building from Source
-
- The most convenient way to obtain the Privoxy sources is to download the
- source tarball from our project download page.
-
- If you like to live on the bleeding edge and are not afraid of using
- possibly unstable development versions, you can check out the
- up-to-the-minute version directly from the CVS repository.
-
- To build Privoxy from source, autoconf, GNU make (gmake), and, of course,
- a C compiler like gcc are required.
-
- When building from a source tarball, first unpack the source:
-
- tar xzvf privoxy-3.0.8-src* [.tgz or .tar.gz]
- cd privoxy-3.0.8
-
- For retrieving the current CVS sources, you'll need a CVS client
- installed. Note that sources from CVS are typically development quality,
- and may not be stable, or well tested. To download CVS source, check the
- Sourceforge documentation, which might give commands like:
-
- cvs -d:pserver:anonymous@ijbswa.cvs.sourceforge.net:/cvsroot/ijbswa login
- cvs -z3 -d:pserver:anonymous@ijbswa.cvs.sourceforge.net:/cvsroot/ijbswa co current
- cd current
-
- This will create a directory named current/, which will contain the source
- tree.
-
- You can also check out any Privoxy "branch", just exchange the current
- name with the wanted branch name (Example: v_3_0_branch for the 3.0 cvs
- tree).
-
- It is also strongly recommended to not run Privoxy as root. You should
- configure/install/run Privoxy as an unprivileged user, preferably by
- creating a "privoxy" user and group just for this purpose. See your local
- documentation for the correct command line to do add new users and groups
- (something like adduser, but the command syntax may vary from platform to
- platform).
-
- /etc/passwd might then look like:
-
- privoxy:*:7777:7777:privoxy proxy:/no/home:/no/shell
-
- And then /etc/group, like:
-
- privoxy:*:7777:
-
- Some binary packages may do this for you.
-
- Then, to build from either unpacked tarball or CVS source:
-
- autoheader
- autoconf
- ./configure # (--help to see options)
- make # (the make from GNU, sometimes called gmake)
- su # Possibly required
- make -n install # (to see where all the files will go)
- make -s install # (to really install, -s to silence output)
-
- Using GNU make, you can have the first four steps automatically done for
- you by just typing:
-
- make
-
- in the freshly downloaded or unpacked source directory.
-
- To build an executable with security enhanced features so that users
- cannot easily bypass the proxy (e.g. "Go There Anyway"), or alter their
- own configurations, configure like this:
-
- ./configure --disable-toggle --disable-editor --disable-force
-
- Then build as above. In Privoxy 3.0.7 and later, all of these options can
- also be disabled through the configuration file.
-
- WARNING: If installing as root, the install will fail unless a non-root
- user or group is specified, or a privoxy user and group already exist on
- the system. If a non-root user is specified, and no group, then the
- installation will try to also use a group of the same name as "user". If a
- group is specified (and no user), then the support files will be installed
- as writable by that group, and owned by the user running the installation.
-
- configure accepts --with-user and --with-group options for setting user
- and group ownership of the configuration files (which need to be writable
- by the daemon). The specified user must already exist. When starting
- Privoxy, it must be run as this same user to insure write access to
- configuration and log files!
-
- Alternately, you can specify user and group on the make command line, but
- be sure both already exist:
-
- make -s install USER=privoxy GROUP=privoxy
-
- The default installation path for make install is /usr/local. This may of
- course be customized with the various ./configure path options. If you are
- doing an install to anywhere besides /usr/local, be sure to set the
- appropriate paths with the correct configure options (./configure --help).
- Non-privileged users must of course have write access permissions to
- wherever the target installation is going.
-
- If you do install to /usr/local, the install will use
- sysconfdir=$prefix/etc/privoxy by default. All other destinations, and the
- direct usage of --sysconfdir flag behave like normal, i.e. will not add
- the extra privoxy directory. This is for a safer install, as there may
- already exist another program that uses a file with the "config" name, and
- thus makes /usr/local/etc cleaner.
-
- If installing to /usr/local, the documentation will go by default to
- $prefix/share/doc. But if this directory doesn't exist, it will then try
- $prefix/doc and install there before creating a new $prefix/share/doc just
- for Privoxy.
-
- Again, if the installs goes to /usr/local, the localstatedir (ie: var/)
- will default to /var instead of $prefix/var so the logs will go to
- /var/log/privoxy/, and the pid file will be created in
- /var/run/privoxy.pid.
-
- make install will attempt to set the correct values in config (main
- configuration file). You should check this to make sure all values are
- correct. If appropriate, an init script will be installed, but it is up to
- the user to determine how and where to start Privoxy. The init script
- should be checked for correct paths and values, if anything other than a
- default install is done.
-
- If install finds previous versions of local configuration files, most of
- these will not be overwritten, and the new ones will be installed with a
- "new" extension. default.action, default.filter, and standard.action will
- be overwritten. You will then need to manually update the other installed
- configuration files as needed. The default template files will be
- overwritten. If you have customized, local templates, these should be
- stored safely in a separate directory and defined in config by the
- "templdir" directive. It is of course wise to always back-up any important
- configuration files "just in case". If a previous version of Privoxy is
- already running, you will have to restart it manually.
-
- For more detailed instructions on how to build Redhat RPMs, Windows
- self-extracting installers, building on platforms with special
- requirements etc, please consult the developer manual.
-
- --------------------------------------------------------------------------
-
- 2.3. Keeping your Installation Up-to-Date
-
- As user feedback comes in and development continues, we will make updated
- versions of both the main actions file (as a separate package) and the
- software itself (including the actions file) available for download.
-
- If you wish to receive an email notification whenever we release updates
- of Privoxy or the actions file, subscribe to our announce mailing list,
- ijbswa-announce@lists.sourceforge.net.
-
- In order not to lose your personal changes and adjustments when updating
- to the latest default.action file we strongly recommend that you use
- user.action and user.filter for your local customizations of Privoxy. See
- the Chapter on actions files for details.
-
- --------------------------------------------------------------------------
-
-3. What's New in this Release
-
- There are many improvements and new features since Privoxy 3.0.6, the last
- stable release:
-
- * Two new actions server-header-tagger and client-header-tagger that can
- be used to create arbitrary "tags" based on client and server headers.
- These "tags" can then subsequently be used to control the other
- actions used for the current request, greatly increasing Privoxy's
- flexibility and selectivity. See tag patterns for more information on
- tags.
-
- * Header filtering is done with dedicated header filters now. As a
- result the actions "filter-client-headers" and "filter-server-headers"
- that were introduced with Privoxy 3.0.5 to apply content filters to
- the headers have been removed. See the new actions
- server-header-filter and client-header-filter for details.
-
- * There are four new options for the main config file:
-
- * allow-cgi-request-crunching which allows requests for Privoxy's
- internal CGI pages to be blocked, redirected or (un)trusted like
- ordinary requests.
-
- * split-large-forms that will work around a browser bug that caused
- IE6 and IE7 to ignore the Submit button on the Privoxy's
- edit-actions-for-url CGI page.
-
- * accept-intercepted-requests which allows to combine Privoxy with
- any packet filter to create an intercepting proxy for HTTP/1.1
- requests (and for HTTP/1.0 requests with Host header set). This
- means clients can be forced to use Privoxy even if their proxy
- settings are configured differently.
-
- * templdir to designate an alternate location for Privoxy's locally
- customized CGI templates so that these are not overwritten during
- upgrades.
-
- * A new command line option --pre-chroot-nslookup hostname to initialize
- the resolver library before chroot'ing. On some systems this reduces
- the number of files that must be copied into the chroot tree. (Patch
- provided by Stephen Gildea)
-
- * The forward-override action allows changing of the forwarding settings
- through the actions files. Combined with tags, this allows to choose
- the forwarder based on client headers like the User-Agent, or the
- request origin.
-
- * The redirect action can now use regular expression substitutions
- against the original URL.
-
- * zlib support is now available as a compile time option to filter
- compressed content. Patch provided by Wil Mahan.
-
- * Improve various filters, and add new ones.
-
- * Include support for RFC 3253 so that Subversion works with Privoxy.
- Patch provided by Petr Kadlec.
-
- * Logging can be completely turned off by not specifying a logfile
- directive.
-
- * A number of improvements to Privoxy's internal CGI pages, including
- the use of favicons for error and control pages.
-
- * Many bugfixes, memory leaks addressed, code improvements, and logging
- improvements.
-
- For a more detailed list of changes please have a look at the ChangeLog.
-
- --------------------------------------------------------------------------
-
- 3.1. Note to Upgraders
-
- A quick list of things to be aware of before upgrading from earlier
- versions of Privoxy:
-
- * The recommended way to upgrade Privoxy is to backup your old
- configuration files, install the new ones, verify that Privoxy is
- working correctly and finally merge back your changes using diff and
- maybe patch.
-
- There are a number of new features in each Privoxy release and most of
- them have to be explicitly enabled in the configuration files. Old
- configuration files obviously don't do that and due to syntax changes
- using old configuration files with a new Privoxy isn't always possible
- anyway.
-
- * Note that some installers remove earlier versions completely,
- including configuration files, therefore you should really save any
- important configuration files!
-
- * On the other hand, other installers don't overwrite existing
- configuration files, thinking you will want to do that yourself.
-
- * standard.action now only includes the enabled actions. Not all actions
- as before.
-
- * In the default configuration only fatal errors are logged now. You can
- change that in the debug section of the configuration file. You may
- also want to enable more verbose logging until you verified that the
- new Privoxy version is working as expected.
-
- * Three other config file settings are now off by default:
- enable-remote-toggle, enable-remote-http-toggle, and
- enable-edit-actions. If you use or want these, you will need to
- explicitly enable them, and be aware of the security issues involved.
-
- * The "filter-client-headers" and "filter-server-headers" actions that
- were introduced with Privoxy 3.0.5 to apply content filters to the
- headers have been removed and replaced with new actions. See the
- What's New section above.
-
- --------------------------------------------------------------------------
-
-4. Quickstart to Using Privoxy
-
- * Install Privoxy. See the Installation Section below for platform
- specific information.
-
- * Advanced users and those who want to offer Privoxy service to more
- than just their local machine should check the main config file,
- especially the security-relevant options. These are off by default.
-
- * Start Privoxy, if the installation program has not done this already
- (may vary according to platform). See the section Starting Privoxy.
-
- * Set your browser to use Privoxy as HTTP and HTTPS (SSL) proxy by
- setting the proxy configuration for address of 127.0.0.1 and port
- 8118. DO NOT activate proxying for FTP or any protocols besides HTTP
- and HTTPS (SSL) unless you intend to prevent your browser from using
- these protocols.
-
- * Flush your browser's disk and memory caches, to remove any cached ad
- images. If using Privoxy to manage cookies, you should remove any
- currently stored cookies too.
-
- * A default installation should provide a reasonable starting point for
- most. There will undoubtedly be occasions where you will want to
- adjust the configuration, but that can be dealt with as the need
- arises. Little to no initial configuration is required in most cases,
- you may want to enable the web-based action editor though. Be sure to
- read the warnings first.
-
- See the Configuration section for more configuration options, and how
- to customize your installation. You might also want to look at the
- next section for a quick introduction to how Privoxy blocks ads and
- banners.
-
- * If you experience ads that slip through, innocent images that are
- blocked, or otherwise feel the need to fine-tune Privoxy's behavior,
- take a look at the actions files. As a quick start, you might find the
- richly commented examples helpful. You can also view and edit the
- actions files through the web-based user interface. The Appendix
- "Troubleshooting: Anatomy of an Action" has hints on how to understand
- and debug actions that "misbehave".
-
- * Please see the section Contacting the Developers on how to report
- bugs, problems with websites or to get help.
-
- * Now enjoy surfing with enhanced control, comfort and privacy!
-
- --------------------------------------------------------------------------
-
- 4.1. Quickstart to Ad Blocking
-
- Ad blocking is but one of Privoxy's array of features. Many of these
- features are for the technically minded advanced user. But, ad and banner
- blocking is surely common ground for everybody.
-
- This section will provide a quick summary of ad blocking so you can get up
- to speed quickly without having to read the more extensive information
- provided below, though this is highly recommended.
-
- First a bit of a warning ... blocking ads is much like blocking SPAM: the
- more aggressive you are about it, the more likely you are to block things
- that were not intended. And the more likely that some things may not work
- as intended. So there is a trade off here. If you want extreme ad free
- browsing, be prepared to deal with more "problem" sites, and to spend more
- time adjusting the configuration to solve these unintended consequences.
- In short, there is not an easy way to eliminate all ads. Either take the
- easy way and settle for most ads blocked with the default configuration,
- or jump in and tweak it for your personal surfing habits and preferences.
-
- Secondly, a brief explanation of Privoxy's "actions". "Actions" in this
- context, are the directives we use to tell Privoxy to perform some task
- relating to HTTP transactions (i.e. web browsing). We tell Privoxy to take
- some "action". Each action has a unique name and function. While there are
- many potential actions in Privoxy's arsenal, only a few are used for ad
- blocking. Actions, and action configuration files, are explained in depth
- below.
-
- Actions are specified in Privoxy's configuration, followed by one or more
- URLs to which the action should apply. URLs can actually be URL type
- patterns that use wildcards so they can apply potentially to a range of
- similar URLs. The actions, together with the URL patterns are called a
- section.
-
- When you connect to a website, the full URL will either match one or more
- of the sections as defined in Privoxy's configuration, or not. If so, then
- Privoxy will perform the respective actions. If not, then nothing special
- happens. Furthermore, web pages may contain embedded, secondary URLs that
- your web browser will use to load additional components of the page, as it
- parses the original page's HTML content. An ad image for instance, is just
- an URL embedded in the page somewhere. The image itself may be on the same
- server, or a server somewhere else on the Internet. Complex web pages will
- have many such embedded URLs. Privoxy can deal with each URL individually,
- so, for instance, the main page text is not touched, but images from
- such-and-such server are blocked.
-
- The most important actions for basic ad blocking are: block,
- handle-as-image, handle-as-empty-document,and set-image-blocker:
-
- * block - this is perhaps the single most used action, and is
- particularly important for ad blocking. This action stops any contact
- between your browser and any URL patterns that match this action's
- configuration. It can be used for blocking ads, but also anything that
- is determined to be unwanted. By itself, it simply stops any
- communication with the remote server and sends Privoxy's own built-in
- BLOCKED page instead to let you now what has happened (with some
- exceptions, see below).
-
- * handle-as-image - tells Privoxy to treat this URL as an image.
- Privoxy's default configuration already does this for all common image
- types (e.g. GIF), but there are many situations where this is not so
- easy to determine. So we'll force it in these cases. This is
- particularly important for ad blocking, since only if we know that
- it's an image of some kind, can we replace it with an image of our
- choosing, instead of the Privoxy BLOCKED page (which would only result
- in a "broken image" icon). There are some limitations to this though.
- For instance, you can't just brute-force an image substitution for an
- entire HTML page in most situations.
-
- * handle-as-empty-document - sends an empty document instead of
- Privoxy's normal BLOCKED HTML page. This is useful for file types that
- are neither HTML nor images, such as blocking JavaScript files.
-
- * set-image-blocker - tells Privoxy what to display in place of an ad
- image that has hit a block rule. For this to come into play, the URL
- must match a block action somewhere in the configuration, and, it must
- also match an handle-as-image action.
-
- The configuration options on what to display instead of the ad are:
-
- pattern - a checkerboard pattern, so that an ad replacement is
- obvious. This is the default.
-
- blank - A very small empty GIF image is displayed. This is the
- so-called "invisible" configuration option.
-
- http://<URL> - A redirect to any image anywhere of the user's
- choosing (advanced usage).
-
- Advanced users will eventually want to explore Privoxy filters as well.
- Filters are very different from blocks. A "block" blocks a site, page, or
- unwanted contented. Filters are a way of filtering or modifying what is
- actually on the page. An example filter usage: a text replacement of
- "no-no" for "nasty-word". That is a very simple example. This process can
- be used for ad blocking, but it is more in the realm of advanced usage and
- has some pitfalls to be wary off.
-
- The quickest way to adjust any of these settings is with your browser
- through the special Privoxy editor at
- http://config.privoxy.org/show-status (shortcut: http://p.p/show-status).
- This is an internal page, and does not require Internet access.
-
- Note that as of Privoxy 3.0.7 beta the action editor is disabled by
- default. Check the enable-edit-actions section in the configuration file
- to learn why and in which cases it's safe to enable again.
-
- If you decided to enable the action editor, select the appropriate
- "actions" file, and click "Edit". It is best to put personal or local
- preferences in user.action since this is not meant to be overwritten
- during upgrades, and will over-ride the settings in other files. Here you
- can insert new "actions", and URLs for ad blocking or other purposes, and
- make other adjustments to the configuration. Privoxy will detect these
- changes automatically.
-
- A quick and simple step by step example:
-
- * Right click on the ad image to be blocked, then select "Copy Link
- Location" from the pop-up menu.
-
- * Set your browser to http://config.privoxy.org/show-status
-
- * Find user.action in the top section, and click on "Edit":
-
- Figure 1. Actions Files in Use
-
- * You should have a section with only block listed under "Actions:". If
- not, click a "Insert new section below" button, and in the new section
- that just appeared, click the Edit button right under the word
- "Actions:". This will bring up a list of all actions. Find block near
- the top, and click in the "Enabled" column, then "Submit" just below
- the list.
-
- * Now, in the block actions section, click the "Add" button, and paste
- the URL the browser got from "Copy Link Location". Remove the http://
- at the beginning of the URL. Then, click "Submit" (or "OK" if in a
- pop-up window).
-
- * Now go back to the original page, and press SHIFT-Reload (or flush all
- browser caches). The image should be gone now.
-
- This is a very crude and simple example. There might be good reasons to
- use a wildcard pattern match to include potentially similar images from
- the same site. For a more extensive explanation of "patterns", and the
- entire actions concept, see the Actions section.
-
- For advanced users who want to hand edit their config files, you might
- want to now go to the Actions Files Tutorial. The ideas explained therein
- also apply to the web-based editor.
-
- There are also various filters that can be used for ad blocking (filters
- are a special subset of actions). These fall into the "advanced" usage
- category, and are explained in depth in later sections.
-
- --------------------------------------------------------------------------
-
-5. Starting Privoxy
-
- Before launching Privoxy for the first time, you will want to configure
- your browser(s) to use Privoxy as a HTTP and HTTPS (SSL) proxy. The
- default is 127.0.0.1 (or localhost) for the proxy address, and port 8118
- (earlier versions used port 8000). This is the one configuration step that
- must be done!
-
- Please note that Privoxy can only proxy HTTP and HTTPS traffic. It will
- not work with FTP or other protocols.
-
- Figure 2. Proxy Configuration Showing Mozilla/Netscape HTTP and HTTPS
- (SSL) Settings
-
- With Firefox, this is typically set under:
-
- Tools -> Options -> Advanced -> Network ->Connection -> Settings
-
-
- Or optionally on some platforms:
-
- Edit -> Preferences -> General -> Connection Settings -> Manual Proxy
- Configuration
-
-
- With Netscape (and Mozilla), this can be set under:
-
- Edit -> Preferences -> Advanced -> Proxies -> HTTP Proxy
-
-
- For Internet Explorer v.5-7:
-
- Tools -> Internet Options -> Connections -> LAN Settings
-
- Then, check "Use Proxy" and fill in the appropriate info (Address:
- 127.0.0.1, Port: 8118). Include HTTPS (SSL), if you want HTTPS proxy
- support too (sometimes labeled "Secure"). Make sure any checkboxes like
- "Use the same proxy server for all protocols" is UNCHECKED. You want only
- HTTP and HTTPS (SSL)!
-
- Figure 3. Proxy Configuration Showing Internet Explorer HTTP and HTTPS
- (Secure) Settings
-
- After doing this, flush your browser's disk and memory caches to force a
- re-reading of all pages and to get rid of any ads that may be cached.
- Remove any cookies, if you want Privoxy to manage that. You are now ready
- to start enjoying the benefits of using Privoxy!
-
- Privoxy itself is typically started by specifying the main configuration
- file to be used on the command line. If no configuration file is specified
- on the command line, Privoxy will look for a file named config in the
- current directory. Except on Win32 where it will try config.txt.
-
- --------------------------------------------------------------------------
-
- 5.1. Red Hat and Fedora
-
- A default Red Hat installation may not start Privoxy upon boot. It will
- use the file /etc/privoxy/config as its main configuration file.
-
- # /etc/rc.d/init.d/privoxy start
-
- Or ...
-
- # service privoxy start
-
- --------------------------------------------------------------------------
-
- 5.2. Debian
-
- We use a script. Note that Debian typically starts Privoxy upon booting
- per default. It will use the file /etc/privoxy/config as its main
- configuration file.
-
- # /etc/init.d/privoxy start
-
- --------------------------------------------------------------------------
-
- 5.3. Windows
-
- Click on the Privoxy Icon to start Privoxy. If no configuration file is
- specified on the command line, Privoxy will look for a file named
- config.txt. Note that Windows will automatically start Privoxy when the
- system starts if you chose that option when installing.
-
- Privoxy can run with full Windows service functionality. On Windows only,
- the Privoxy program has two new command line arguments to install and
- uninstall Privoxy as a service. See the Windows Installation instructions
- for details.
-
- --------------------------------------------------------------------------
-
- 5.4. Solaris, NetBSD, FreeBSD, HP-UX and others
-
- Example Unix startup command:
-
- # /usr/sbin/privoxy /etc/privoxy/config
-
- --------------------------------------------------------------------------
-
- 5.5. OS/2
-
- During installation, Privoxy is configured to start automatically when the
- system restarts. You can start it manually by double-clicking on the
- Privoxy icon in the Privoxy folder.
-
- --------------------------------------------------------------------------
-
- 5.6. Mac OSX
-
- During installation, Privoxy is configured to start automatically when the
- system restarts. To start Privoxy manually, double-click on the
- StartPrivoxy.command icon in the /Library/Privoxy folder. Or, type this
- command in the Terminal:
-
- /Library/Privoxy/StartPrivoxy.command
-
-
- You will be prompted for the administrator password.
-
- --------------------------------------------------------------------------
-
- 5.7. AmigaOS
-
- Start Privoxy (with RUN <>NIL:) in your startnet script (AmiTCP), in
- s:user-startup (RoadShow), as startup program in your startup script
- (Genesis), or as startup action (Miami and MiamiDx). Privoxy will
- automatically quit when you quit your TCP/IP stack (just ignore the
- harmless warning your TCP/IP stack may display that Privoxy is still
- running).
-
- --------------------------------------------------------------------------
-
- 5.8. Gentoo
-
- A script is again used. It will use the file /etc/privoxy/config as its
- main configuration file.
-
- /etc/init.d/privoxy start
-
-
- Note that Privoxy is not automatically started at boot time by default.
- You can change this with the rc-update command.
-
- rc-update add privoxy default
-
-
- --------------------------------------------------------------------------
-
- 5.9. Command Line Options
-
- Privoxy may be invoked with the following command-line options:
-
- * --version
-
- Print version info and exit. Unix only.
-
- * --help
-
- Print short usage info and exit. Unix only.
-
- * --no-daemon
-
- Don't become a daemon, i.e. don't fork and become process group
- leader, and don't detach from controlling tty. Unix only.
-
- * --pidfile FILE
-
- On startup, write the process ID to FILE. Delete the FILE on exit.
- Failure to create or delete the FILE is non-fatal. If no FILE option
- is given, no PID file will be used. Unix only.
-
- * --user USER[.GROUP]
-
- After (optionally) writing the PID file, assume the user ID of USER,
- and if included the GID of GROUP. Exit if the privileges are not
- sufficient to do so. Unix only.
-
- * --chroot
-
- Before changing to the user ID given in the --user option, chroot to
- that user's home directory, i.e. make the kernel pretend to the
- Privoxy process that the directory tree starts there. If set up
- carefully, this can limit the impact of possible vulnerabilities in
- Privoxy to the files contained in that hierarchy. Unix only.
-
- * --pre-chroot-nslookup hostname
-
- Specifies a hostname to look up before doing a chroot. On some
- systems, initializing the resolver library involves reading config
- files from /etc and/or loading additional shared libraries from /lib.
- On these systems, doing a hostname lookup before the chroot reduces
- the number of files that must be copied into the chroot tree.
-
- For fastest startup speed, a good value is a hostname that is not in
- /etc/hosts but that your local name server (listed in
- /etc/resolv.conf) can resolve without recursion (that is, without
- having to ask any other name servers). The hostname need not exist,
- but if it doesn't, an error message (which can be ignored) will be
- output.
-
- * configfile
-
- If no configfile is included on the command line, Privoxy will look
- for a file named "config" in the current directory (except on Win32
- where it will look for "config.txt" instead). Specify full path to
- avoid confusion. If no config file is found, Privoxy will fail to
- start.
-
- On MS Windows only there are two additional command-line options to allow
- Privoxy to install and run as a service. See the Window Installation
- section for details.
-
- --------------------------------------------------------------------------
-
-6. Privoxy Configuration
-
- All Privoxy configuration is stored in text files. These files can be
- edited with a text editor. Many important aspects of Privoxy can also be
- controlled easily with a web browser.
-
- --------------------------------------------------------------------------
-
- 6.1. Controlling Privoxy with Your Web Browser
-
- Privoxy's user interface can be reached through the special URL
- http://config.privoxy.org/ (shortcut: http://p.p/), which is a built-in
- page and works without Internet access. You will see the following
- section:
-
-
-
- Privoxy Menu
-
- View & change the current configuration
-
- View the source code version numbers
-
- View the request headers.
-
- Look up which actions apply to a URL and why
-
- Toggle Privoxy on or off
-
- Documentation
-
-
- This should be self-explanatory. Note the first item leads to an editor
- for the actions files, which is where the ad, banner, cookie, and URL
- blocking magic is configured as well as other advanced features of
- Privoxy. This is an easy way to adjust various aspects of Privoxy
- configuration. The actions file, and other configuration files, are
- explained in detail below.
-
- "Toggle Privoxy On or Off" is handy for sites that might have problems
- with your current actions and filters. You can in fact use it as a test to
- see whether it is Privoxy causing the problem or not. Privoxy continues to
- run as a proxy in this case, but all manipulation is disabled, i.e.
- Privoxy acts like a normal forwarding proxy. There is even a toggle
- Bookmarklet offered, so that you can toggle Privoxy with one click from
- your browser.
-
- Note that several of the features described above are disabled by default
- in Privoxy 3.0.7 beta and later. Check the configuration file to learn why
- and in which cases it's safe to enable them again.
-
- --------------------------------------------------------------------------
-
- 6.2. Configuration Files Overview
-
- For Unix, *BSD and Linux, all configuration files are located in
- /etc/privoxy/ by default. For MS Windows, OS/2, and AmigaOS these are all
- in the same directory as the Privoxy executable.
-
- The installed defaults provide a reasonable starting point, though some
- settings may be aggressive by some standards. For the time being, the
- principle configuration files are:
-
- * The main configuration file is named config on Linux, Unix, BSD, OS/2,
- and AmigaOS and config.txt on Windows. This is a required file.
-
- * default.action (the main actions file) is used to define which
- "actions" relating to banner-blocking, images, pop-ups, content
- modification, cookie handling etc should be applied by default. It
- also defines many exceptions (both positive and negative) from this
- default set of actions that enable Privoxy to selectively eliminate
- the junk, and only the junk, on as many websites as possible.
-
- Multiple actions files may be defined in config. These are processed
- in the order they are defined. Local customizations and locally
- preferred exceptions to the default policies as defined in
- default.action (which you will most probably want to define sooner or
- later) are probably best applied in user.action, where you can
- preserve them across upgrades. standard.action is only for Privoxy's
- internal use.
-
- There is also a web based editor that can be accessed from
- http://config.privoxy.org/show-status (Shortcut:
- http://p.p/show-status) for the various actions files.
-
- * "Filter files" (the filter file) can be used to re-write the raw page
- content, including viewable text as well as embedded HTML and
- JavaScript, and whatever else lurks on any given web page. The
- filtering jobs are only pre-defined here; whether to apply them or not
- is up to the actions files. default.filter includes various filters
- made available for use by the developers. Some are much more intrusive
- than others, and all should be used with caution. You may define
- additional filter files in config as you can with actions files. We
- suggest user.filter for any locally defined filters or customizations.
-
- The syntax of the configuration and filter files may change between
- different Privoxy versions, unfortunately some enhancements cost backwards
- compatibility.
-
- All files use the "#" character to denote a comment (the rest of the line
- will be ignored) and understand line continuation through placing a
- backslash ("\") as the very last character in a line. If the # is preceded
- by a backslash, it looses its special function. Placing a # in front of an
- otherwise valid configuration line to prevent it from being interpreted is
- called "commenting out" that line. Blank lines are ignored.
-
- The actions files and filter files can use Perl style regular expressions
- for maximum flexibility.
-
- After making any changes, there is no need to restart Privoxy in order for
- the changes to take effect. Privoxy detects such changes automatically.
- Note, however, that it may take one or two additional requests for the
- change to take effect. When changing the listening address of Privoxy,
- these "wake up" requests must obviously be sent to the old listening
- address.
-
- --------------------------------------------------------------------------
-
-7. The Main Configuration File
-
- Again, the main configuration file is named config on Linux/Unix/BSD and
- OS/2, and config.txt on Windows. Configuration lines consist of an initial
- keyword followed by a list of values, all separated by whitespace (any
- number of spaces or tabs). For example:
-
- confdir /etc/privoxy
-
- Assigns the value /etc/privoxy to the option confdir and thus indicates
- that the configuration directory is named "/etc/privoxy/".
-
- All options in the config file except for confdir and logdir are optional.
- Watch out in the below description for what happens if you leave them
- unset.
-
- The main config file controls all aspects of Privoxy's operation that are
- not location dependent (i.e. they apply universally, no matter where you
- may be surfing).
-
- --------------------------------------------------------------------------
-
- 7.1. Local Set-up Documentation
-
- If you intend to operate Privoxy for more users than just yourself, it
- might be a good idea to let them know how to reach you, what you block and
- why you do that, your policies, etc.
-
- --------------------------------------------------------------------------
-
- 7.1.1. user-manual
-
- Specifies:
-
- Location of the Privoxy User Manual.
-
- Type of value:
-
- A fully qualified URI
-
- Default value:
-
- Unset
-
- Effect if unset:
-
- http://www.privoxy.org/version/user-manual/ will be used, where
- version is the Privoxy version.
-
- Notes:
-
- The User Manual URI is the single best source of information on
- Privoxy, and is used for help links from some of the internal CGI
- pages. The manual itself is normally packaged with the binary
- distributions, so you probably want to set this to a locally
- installed copy.
-
- Examples:
-
- The best all purpose solution is simply to put the full local PATH
- to where the User Manual is located:
-
- user-manual /usr/share/doc/privoxy/user-manual
-
- The User Manual is then available to anyone with access to
- Privoxy, by following the built-in URL:
- http://config.privoxy.org/user-manual/ (or the shortcut:
- http://p.p/user-manual/).
-
- If the documentation is not on the local system, it can be
- accessed from a remote server, as:
-
- user-manual http://example.com/privoxy/user-manual/
-
- +---------------------------------------------------------+
- | Warning |
- |---------------------------------------------------------|
- | If set, this option should be the first option in the |
- | config file, because it is used while the config file |
- | is being read on start-up. |
- +---------------------------------------------------------+
-
- --------------------------------------------------------------------------
-
- 7.1.2. trust-info-url
-
- Specifies:
-
- A URL to be displayed in the error page that users will see if
- access to an untrusted page is denied.
-
- Type of value:
-
- URL
-
- Default value:
-
- Two example URLs are provided
-
- Effect if unset:
-
- No links are displayed on the "untrusted" error page.
-
- Notes:
-
- The value of this option only matters if the experimental trust
- mechanism has been activated. (See trustfile below.)
-
- If you use the trust mechanism, it is a good idea to write up some
- on-line documentation about your trust policy and to specify the
- URL(s) here. Use multiple times for multiple URLs.
-
- The URL(s) should be added to the trustfile as well, so users
- don't end up locked out from the information on why they were
- locked out in the first place!
-
- --------------------------------------------------------------------------
-
- 7.1.3. admin-address
-
- Specifies:
-
- An email address to reach the Privoxy administrator.
-
- Type of value:
-
- Email address
-
- Default value:
-
- Unset
-
- Effect if unset:
-
- No email address is displayed on error pages and the CGI user
- interface.
-
- Notes:
-
- If both admin-address and proxy-info-url are unset, the whole
- "Local Privoxy Support" box on all generated pages will not be
- shown.
-
- --------------------------------------------------------------------------
-
- 7.1.4. proxy-info-url
-
- Specifies:
-
- A URL to documentation about the local Privoxy setup,
- configuration or policies.
-
- Type of value:
-
- URL
-
- Default value:
-
- Unset
-
- Effect if unset:
-
- No link to local documentation is displayed on error pages and the
- CGI user interface.
-
- Notes:
-
- If both admin-address and proxy-info-url are unset, the whole
- "Local Privoxy Support" box on all generated pages will not be
- shown.
-
- This URL shouldn't be blocked ;-)
-
- --------------------------------------------------------------------------
-
- 7.2. Configuration and Log File Locations
-
- Privoxy can (and normally does) use a number of other files for additional
- configuration, help and logging. This section of the configuration file
- tells Privoxy where to find those other files.
-
- The user running Privoxy, must have read permission for all configuration
- files, and write permission to any files that would be modified, such as
- log files and actions files.
-
- --------------------------------------------------------------------------
-
- 7.2.1. confdir
-
- Specifies:
-
- The directory where the other configuration files are located.
-
- Type of value:
-
- Path name
-
- Default value:
-
- /etc/privoxy (Unix) or Privoxy installation dir (Windows)
-
- Effect if unset:
-
- Mandatory
-
- Notes:
-
- No trailing "/", please.
-
- --------------------------------------------------------------------------
-
- 7.2.2. templdir
-
- Specifies:
-
- An alternative directory where the templates are loaded from.
-
- Type of value:
-
- Path name
-
- Default value:
-
- unset
-
- Effect if unset:
-
- The templates are assumed to be located in confdir/template.
-
- Notes:
-
- Privoxy's original templates are usually overwritten with each
- update. Use this option to relocate customized templates that
- should be kept. As template variables might change between
- updates, you shouldn't expect templates to work with Privoxy
- releases other than the one they were part of, though.
-
- --------------------------------------------------------------------------
-
- 7.2.3. logdir
-
- Specifies:
-
- The directory where all logging takes place (i.e. where logfile
- and jarfile are located).
-
- Type of value:
-
- Path name
-
- Default value:
-
- /var/log/privoxy (Unix) or Privoxy installation dir (Windows)
-
- Effect if unset:
-
- Mandatory
-
- Notes:
-
- No trailing "/", please.
-
- --------------------------------------------------------------------------
-
- 7.2.4. actionsfile
-
- Specifies:
-
- The actions file(s) to use
-
- Type of value:
-
- Complete file name, relative to confdir
-
- Default values:
-
- standard.action # Internal purposes, no editing recommended
- default.action # Main actions file
- user.action # User customizations
-
- Effect if unset:
-
- No actions are taken at all. More or less neutral proxying.
-
- Notes:
-
- Multiple actionsfile lines are permitted, and are in fact
- recommended!
-
- The default values include standard.action, which is used for
- internal purposes and should be loaded, default.action, which is
- the "main" actions file maintained by the developers, and
- user.action, where you can make your personal additions.
-
- Actions files contain all the per site and per URL configuration
- for ad blocking, cookie management, privacy considerations, etc.
- There is no point in using Privoxy without at least one actions
- file.
-
- Note that since Privoxy 3.0.7, the complete filename, including
- the ".action" extension has to be specified. The syntax change was
- necessary to be consistent with the other file options and to
- allow previously forbidden characters.
-
- --------------------------------------------------------------------------
-
- 7.2.5. filterfile
-
- Specifies:
-
- The filter file(s) to use
-
- Type of value:
-
- File name, relative to confdir
-
- Default value:
-
- default.filter (Unix) or default.filter.txt (Windows)
-
- Effect if unset:
-
- No textual content filtering takes place, i.e. all +filter{name}
- actions in the actions files are turned neutral.
-
- Notes:
-
- Multiple filterfile lines are permitted.
-
- The filter files contain content modification rules that use
- regular expressions. These rules permit powerful changes on the
- content of Web pages, and optionally the headers as well, e.g.,
- you could try to disable your favorite JavaScript annoyances,
- re-write the actual displayed text, or just have some fun playing
- buzzword bingo with web pages.
-
- The +filter{name} actions rely on the relevant filter (name) to be
- defined in a filter file!
-
- A pre-defined filter file called default.filter that contains a
- number of useful filters for common problems is included in the
- distribution. See the section on the filter action for a list.
-
- It is recommended to place any locally adapted filters into a
- separate file, such as user.filter.
-
- --------------------------------------------------------------------------
-
- 7.2.6. logfile
-
- Specifies:
-
- The log file to use
-
- Type of value:
-
- File name, relative to logdir
-
- Default value:
-
- Unset (commented out). When activated: logfile (Unix) or
- privoxy.log (Windows).
-
- Effect if unset:
-
- No logfile is written.
-
- Notes:
-
- The logfile is where all logging and error messages are written.
- The level of detail and number of messages are set with the debug
- option (see below). The logfile can be useful for tracking down a
- problem with Privoxy (e.g., it's not blocking an ad you think it
- should block) and it can help you to monitor what your browser is
- doing.
-
- Depending on the debug options below, the logfile may be a privacy
- risk if third parties can get access to it. As most users will
- never look at it, Privoxy 3.0.7 and later only log fatal errors by
- default.
-
- For most troubleshooting purposes, you will have to change that,
- please refer to the debugging section for details.
-
- Your logfile will grow indefinitely, and you will probably want to
- periodically remove it. On Unix systems, you can do this with a
- cron job (see "man cron"). For Red Hat based Linux distributions,
- a logrotate script has been included.
-
- Any log files must be writable by whatever user Privoxy is being
- run as (on Unix, default user id is "privoxy").
-
- --------------------------------------------------------------------------
-
- 7.2.7. jarfile
-
- Specifies:
-
- The file to store intercepted cookies in
-
- Type of value:
-
- File name, relative to logdir
-
- Default value:
-
- Unset (commented out). When activated: jarfile (Unix) or
- privoxy.jar (Windows).
-
- Effect if unset:
-
- Intercepted cookies are not stored in a dedicated log file.
-
- Notes:
-
- The jarfile may grow to ridiculous sizes over time.
-
- If debug 8 (show header parsing) is enabled, cookies are also
- written to the logfile with the rest of the headers. Therefore
- this option isn't very useful and may be removed in future
- releases. Please report to the developers if you are still using
- it.
-
- --------------------------------------------------------------------------
-
- 7.2.8. trustfile
-
- Specifies:
-
- The name of the trust file to use
-
- Type of value:
-
- File name, relative to confdir
-
- Default value:
-
- Unset (commented out). When activated: trust (Unix) or trust.txt
- (Windows)
-
- Effect if unset:
-
- The entire trust mechanism is disabled.
-
- Notes:
-
- The trust mechanism is an experimental feature for building
- white-lists and should be used with care. It is NOT recommended
- for the casual user.
-
- If you specify a trust file, Privoxy will only allow access to
- sites that are specified in the trustfile. Sites can be listed in
- one of two ways:
-
- Prepending a ~ character limits access to this site only (and any
- sub-paths within this site), e.g. ~www.example.com allows access
- to ~www.example.com/features/news.html, etc.
-
- Or, you can designate sites as trusted referrers, by prepending
- the name with a + character. The effect is that access to
- untrusted sites will be granted -- but only if a link from this
- trusted referrer was used to get there. The link target will then
- be added to the "trustfile" so that future, direct accesses will
- be granted. Sites added via this mechanism do not become trusted
- referrers themselves (i.e. they are added with a ~ designation).
- There is a limit of 512 such entries, after which new entries will
- not be made.
-
- If you use the + operator in the trust file, it may grow
- considerably over time.
-
- It is recommended that Privoxy be compiled with the
- --disable-force, --disable-toggle and --disable-editor options, if
- this feature is to be used.
-
- Possible applications include limiting Internet access for
- children.
-
- --------------------------------------------------------------------------
-
- 7.3. Debugging
-
- These options are mainly useful when tracing a problem. Note that you
- might also want to invoke Privoxy with the --no-daemon command line option
- when debugging.
-
- --------------------------------------------------------------------------
-
- 7.3.1. debug
-
- Specifies:
-
- Key values that determine what information gets logged.
-
- Type of value:
-
- Integer values
-
- Default value:
-
- 0 (i.e.: only fatal errors (that cause Privoxy to exit) are
- logged)
-
- Effect if unset:
-
- Default value is used (see above).
-
- Notes:
-
- The available debug levels are:
-
- debug 1 # log each request destination (and the crunch reason if Privoxy intercepted the request)
- debug 2 # show each connection status
- debug 4 # show I/O status
- debug 8 # show header parsing
- debug 16 # log all data written to the network into the logfile
- debug 32 # debug force feature
- debug 64 # debug regular expression filters
- debug 128 # debug redirects
- debug 256 # debug GIF de-animation
- debug 512 # Common Log Format
- debug 1024 # debug kill pop-ups
- debug 2048 # CGI user interface
- debug 4096 # Startup banner and warnings.
- debug 8192 # Non-fatal errors
-
- To select multiple debug levels, you can either add them or use
- multiple debug lines.
-
- A debug level of 1 is informative because it will show you each
- request as it happens. 1, 4096 and 8192 are recommended so that
- you will notice when things go wrong. The other levels are
- probably only of interest if you are hunting down a specific
- problem. They can produce a hell of an output (especially 16).
-
- Privoxy used to ship with the debug levels recommended above
- enabled by default, but due to privacy concerns 3.0.7 and later
- are configured to only log fatal errors.
-
- If you are used to the more verbose settings, simply enable the
- debug lines below again.
-
- If you want to use pure CLF (Common Log Format), you should set
- "debug 512" ONLY and not enable anything else.
-
- Privoxy has a hard-coded limit for the length of log messages. If
- it's reached, messages are logged truncated and marked with "...
- [too long, truncated]".
-
- Please don't file any support requests without trying to reproduce
- the problem with increased debug level first. Once you read the
- log messages, you may even be able to solve the problem on your
- own.
-
- --------------------------------------------------------------------------
-
- 7.3.2. single-threaded
-
- Specifies:
-
- Whether to run only one server thread.
-
- Type of value:
-
- None
-
- Default value:
-
- Unset
-
- Effect if unset:
-
- Multi-threaded (or, where unavailable: forked) operation, i.e. the
- ability to serve multiple requests simultaneously.
-
- Notes:
-
- This option is only there for debugging purposes. It will
- drastically reduce performance.
-
- --------------------------------------------------------------------------
-
- 7.4. Access Control and Security
-
- This section of the config file controls the security-relevant aspects of
- Privoxy's configuration.
-
- --------------------------------------------------------------------------
-
- 7.4.1. listen-address
-
- Specifies:
-
- The IP address and TCP port on which Privoxy will listen for
- client requests.
-
- Type of value:
-
- [IP-Address]:Port
-
- Default value:
-
- 127.0.0.1:8118
-
- Effect if unset:
-
- Bind to 127.0.0.1 (localhost), port 8118. This is suitable and
- recommended for home users who run Privoxy on the same machine as
- their browser.
-
- Notes:
-
- You will need to configure your browser(s) to this proxy address
- and port.
-
- If you already have another service running on port 8118, or if
- you want to serve requests from other machines (e.g. on your local
- network) as well, you will need to override the default.
-
- If you leave out the IP address, Privoxy will bind to all
- interfaces (addresses) on your machine and may become reachable
- from the Internet. In that case, consider using access control
- lists (ACL's, see below), and/or a firewall.
-
- If you open Privoxy to untrusted users, you will also want to make
- sure that the following actions are disabled: enable-edit-actions
- and enable-remote-toggle
-
- Example:
-
- Suppose you are running Privoxy on a machine which has the address
- 192.168.0.1 on your local private network (192.168.0.0) and has
- another outside connection with a different address. You want it
- to serve requests from inside only:
-
- listen-address 192.168.0.1:8118
-
- --------------------------------------------------------------------------
-
- 7.4.2. toggle
-
- Specifies:
-
- Initial state of "toggle" status
-
- Type of value:
-
- 1 or 0
-
- Default value:
-
- 1
-
- Effect if unset:
-
- Act as if toggled on
-
- Notes:
-
- If set to 0, Privoxy will start in "toggled off" mode, i.e. mostly
- behave like a normal, content-neutral proxy with both ad blocking
- and content filtering disabled. See enable-remote-toggle below.
-
- The windows version will only display the toggle icon in the
- system tray if this option is present.
-
- --------------------------------------------------------------------------
-
- 7.4.3. enable-remote-toggle
-
- Specifies:
-
- Whether or not the web-based toggle feature may be used
-
- Type of value:
-
- 0 or 1
-
- Default value:
-
- 0
-
- Effect if unset:
-
- The web-based toggle feature is disabled.
-
- Notes:
-
- When toggled off, Privoxy mostly acts like a normal,
- content-neutral proxy, i.e. doesn't block ads or filter content.
-
- Access to the toggle feature can not be controlled separately by
- "ACLs" or HTTP authentication, so that everybody who can access
- Privoxy (see "ACLs" and listen-address above) can toggle it for
- all users. So this option is not recommended for multi-user
- environments with untrusted users.
-
- Note that malicious client side code (e.g Java) is also capable of
- using this option.
-
- As a lot of Privoxy users don't read documentation, this feature
- is disabled by default.
-
- Note that you must have compiled Privoxy with support for this
- feature, otherwise this option has no effect.
-
- --------------------------------------------------------------------------
-
- 7.4.4. enable-remote-http-toggle
-
- Specifies:
-
- Whether or not Privoxy recognizes special HTTP headers to change
- its behaviour.
-
- Type of value:
-
- 0 or 1
-
- Default value:
-
- 0
-
- Effect if unset:
-
- Privoxy ignores special HTTP headers.
-
- Notes:
-
- When toggled on, the client can change Privoxy's behaviour by
- setting special HTTP headers. Currently the only supported special
- header is "X-Filter: No", to disable filtering for the ongoing
- request, even if it is enabled in one of the action files.
-
- This feature is disabled by default. If you are using Privoxy in a
- environment with trusted clients, you may enable this feature at
- your discretion. Note that malicious client side code (e.g Java)
- is also capable of using this feature.
-
- This option will be removed in future releases as it has been
- obsoleted by the more general header taggers.
-
- --------------------------------------------------------------------------
-
- 7.4.5. enable-edit-actions
-
- Specifies:
-
- Whether or not the web-based actions file editor may be used
-
- Type of value:
-
- 0 or 1
-
- Default value:
-
- 0
-
- Effect if unset:
-
- The web-based actions file editor is disabled.
-
- Notes:
-
- Access to the editor can not be controlled separately by "ACLs" or
- HTTP authentication, so that everybody who can access Privoxy (see
- "ACLs" and listen-address above) can modify its configuration for
- all users.
-
- This option is not recommended for environments with untrusted
- users and as a lot of Privoxy users don't read documentation, this
- feature is disabled by default.
-
- Note that malicious client side code (e.g Java) is also capable of
- using the actions editor and you shouldn't enable this options
- unless you understand the consequences and are sure your browser
- is configured correctly.
-
- Note that you must have compiled Privoxy with support for this
- feature, otherwise this option has no effect.
-
- --------------------------------------------------------------------------
-
- 7.4.6. enforce-blocks
-
- Specifies:
-
- Whether the user is allowed to ignore blocks and can "go there
- anyway".
-
- Type of value:
-
- 0 or 1
-
- Default value:
-
- 0
-
- Effect if unset:
-
- Blocks are not enforced.
-
- Notes:
-
- Privoxy is mainly used to block and filter requests as a service
- to the user, for example to block ads and other junk that clogs
- the pipes. Privoxy's configuration isn't perfect and sometimes
- innocent pages are blocked. In this situation it makes sense to
- allow the user to enforce the request and have Privoxy ignore the
- block.
-
- In the default configuration Privoxy's "Blocked" page contains a
- "go there anyway" link to adds a special string (the force prefix)
- to the request URL. If that link is used, Privoxy will detect the
- force prefix, remove it again and let the request pass.
-
- Of course Privoxy can also be used to enforce a network policy. In
- that case the user obviously should not be able to bypass any
- blocks, and that's what the "enforce-blocks" option is for. If
- it's enabled, Privoxy hides the "go there anyway" link. If the
- user adds the force prefix by hand, it will not be accepted and
- the circumvention attempt is logged.
-
- Examples:
-
- enforce-blocks 1
-
- --------------------------------------------------------------------------
-
- 7.4.7. ACLs: permit-access and deny-access
-
- Specifies:
-
- Who can access what.
-
- Type of value:
-
- src_addr[/src_masklen] [dst_addr[/dst_masklen]]
-
- Where src_addr and dst_addr are IP addresses in dotted decimal
- notation or valid DNS names, and src_masklen and dst_masklen are
- subnet masks in CIDR notation, i.e. integer values from 2 to 30
- representing the length (in bits) of the network address. The
- masks and the whole destination part are optional.
-
- Default value:
-
- Unset
-
- Effect if unset:
-
- Don't restrict access further than implied by listen-address
-
- Notes:
-
- Access controls are included at the request of ISPs and systems
- administrators, and are not usually needed by individual users.
- For a typical home user, it will normally suffice to ensure that
- Privoxy only listens on the localhost (127.0.0.1) or internal
- (home) network address by means of the listen-address option.
-
- Please see the warnings in the FAQ that Privoxy is not intended to
- be a substitute for a firewall or to encourage anyone to defer
- addressing basic security weaknesses.
-
- Multiple ACL lines are OK. If any ACLs are specified, Privoxy only
- talks to IP addresses that match at least one permit-access line
- and don't match any subsequent deny-access line. In other words,
- the last match wins, with the default being deny-access.
-
- If Privoxy is using a forwarder (see forward below) for a
- particular destination URL, the dst_addr that is examined is the
- address of the forwarder and NOT the address of the ultimate
- target. This is necessary because it may be impossible for the
- local Privoxy to determine the IP address of the ultimate target
- (that's often what gateways are used for).
-
- You should prefer using IP addresses over DNS names, because the
- address lookups take time. All DNS names must resolve! You can not
- use domain patterns like "*.org" or partial domain names. If a DNS
- name resolves to multiple IP addresses, only the first one is
- used.
-
- Denying access to particular sites by ACL may have undesired side
- effects if the site in question is hosted on a machine which also
- hosts other sites (most sites are).
-
- Examples:
-
- Explicitly define the default behavior if no ACL and
- listen-address are set: "localhost" is OK. The absence of a
- dst_addr implies that all destination addresses are OK:
-
- permit-access localhost
-
- Allow any host on the same class C subnet as www.privoxy.org
- access to nothing but www.example.com (or other domains hosted on
- the same system):
-
- permit-access www.privoxy.org/24 www.example.com/32
-
- Allow access from any host on the 26-bit subnet 192.168.45.64 to
- anywhere, with the exception that 192.168.45.73 may not access the
- IP address behind www.dirty-stuff.example.com:
-
- permit-access 192.168.45.64/26
- deny-access 192.168.45.73 www.dirty-stuff.example.com
-
- --------------------------------------------------------------------------
-
- 7.4.8. buffer-limit
-
- Specifies:
-
- Maximum size of the buffer for content filtering.
-
- Type of value:
-
- Size in Kbytes
-
- Default value:
-
- 4096
-
- Effect if unset:
-
- Use a 4MB (4096 KB) limit.
-
- Notes:
-
- For content filtering, i.e. the +filter and +deanimate-gif
- actions, it is necessary that Privoxy buffers the entire document
- body. This can be potentially dangerous, since a server could just
- keep sending data indefinitely and wait for your RAM to exhaust --
- with nasty consequences. Hence this option.
-
- When a document buffer size reaches the buffer-limit, it is
- flushed to the client unfiltered and no further attempt to filter
- the rest of the document is made. Remember that there may be
- multiple threads running, which might require up to buffer-limit
- Kbytes each, unless you have enabled "single-threaded" above.
-
- --------------------------------------------------------------------------
-
- 7.5. Forwarding
-
- This feature allows routing of HTTP requests through a chain of multiple
- proxies.
-
- Forwarding can be used to chain Privoxy with a caching proxy to speed up
- browsing. Using a parent proxy may also be necessary if the machine that
- Privoxy runs on has no direct Internet access.
-
- Note that parent proxies can severely decrease your privacy level. For
- example a parent proxy could add your IP address to the request headers
- and if it's a caching proxy it may add the "Etag" header to revalidation
- requests again, even though you configured Privoxy to remove it. It may
- also ignore Privoxy's header time randomization and use the original
- values which could be used by the server as cookie replacement to track
- your steps between visits.
-
- Also specified here are SOCKS proxies. Privoxy supports the SOCKS 4 and
- SOCKS 4A protocols.
-
- --------------------------------------------------------------------------
-
- 7.5.1. forward
-
- Specifies:
-
- To which parent HTTP proxy specific requests should be routed.
-
- Type of value:
-
- target_pattern http_parent[:port]
-
- where target_pattern is a URL pattern that specifies to which
- requests (i.e. URLs) this forward rule shall apply. Use / to
- denote "all URLs". http_parent[:port] is the DNS name or IP
- address of the parent HTTP proxy through which the requests should
- be forwarded, optionally followed by its listening port (default:
- 8080). Use a single dot (.) to denote "no forwarding".
-
- Default value:
-
- Unset
-
- Effect if unset:
-
- Don't use parent HTTP proxies.
-
- Notes:
-
- If http_parent is ".", then requests are not forwarded to another
- HTTP proxy but are made directly to the web servers.
-
- Multiple lines are OK, they are checked in sequence, and the last
- match wins.
-
- Examples:
-
- Everything goes to an example parent proxy, except SSL on port 443
- (which it doesn't handle):
-
- forward / parent-proxy.example.org:8080
- forward :443 .
-
- Everything goes to our example ISP's caching proxy, except for
- requests to that ISP's sites:
-
- forward / caching-proxy.isp.example.net:8000
- forward .isp.example.net .
-
- --------------------------------------------------------------------------
-
- 7.5.2. forward-socks4 and forward-socks4a
-
- Specifies:
-
- Through which SOCKS proxy (and optionally to which parent HTTP
- proxy) specific requests should be routed.
-
- Type of value:
-
- target_pattern socks_proxy[:port] http_parent[:port]
-
- where target_pattern is a URL pattern that specifies to which
- requests (i.e. URLs) this forward rule shall apply. Use / to
- denote "all URLs". http_parent and socks_proxy are IP addresses in
- dotted decimal notation or valid DNS names (http_parent may be "."
- to denote "no HTTP forwarding"), and the optional port parameters
- are TCP ports, i.e. integer values from 1 to 64535
-
- Default value:
-
- Unset
-
- Effect if unset:
-
- Don't use SOCKS proxies.
-
- Notes:
-
- Multiple lines are OK, they are checked in sequence, and the last
- match wins.
-
- The difference between forward-socks4 and forward-socks4a is that
- in the SOCKS 4A protocol, the DNS resolution of the target
- hostname happens on the SOCKS server, while in SOCKS 4 it happens
- locally.
-
- If http_parent is ".", then requests are not forwarded to another
- HTTP proxy but are made (HTTP-wise) directly to the web servers,
- albeit through a SOCKS proxy.
-
- Examples:
-
- From the company example.com, direct connections are made to all
- "internal" domains, but everything outbound goes through their
- ISP's proxy by way of example.com's corporate SOCKS 4A gateway to
- the Internet.
-
- forward-socks4a / socks-gw.example.com:1080 www-cache.isp.example.net:8080
- forward .example.com .
-
- A rule that uses a SOCKS 4 gateway for all destinations but no
- HTTP parent looks like this:
-
- forward-socks4 / socks-gw.example.com:1080 .
-
- To chain Privoxy and Tor, both running on the same system, you
- would use something like:
-
- forward-socks4a / 127.0.0.1:9050 .
-
- The public Tor network can't be used to reach your local network,
- if you need to access local servers you therefore might want to
- make some exceptions:
-
- forward 192.168.*.*/ .
- forward 10.*.*.*/ .
- forward 127.*.*.*/ .
-
- Unencrypted connections to systems in these address ranges will be
- as (un)secure as the local network is, but the alternative is that
- you can't reach the local network through Privoxy at all. Of
- course this may actually be desired and there is no reason to make
- these exceptions if you aren't sure you need them.
-
- If you also want to be able to reach servers in your local network
- by using their names, you will need additional exceptions that
- look like this:
-
- forward localhost/ .
-
- --------------------------------------------------------------------------
-
- 7.5.3. Advanced Forwarding Examples
-
- If you have links to multiple ISPs that provide various special content
- only to their subscribers, you can configure multiple Privoxies which have
- connections to the respective ISPs to act as forwarders to each other, so
- that your users can see the internal content of all ISPs.
-
- Assume that host-a has a PPP connection to isp-a.example.net. And host-b
- has a PPP connection to isp-b.example.org. Both run Privoxy. Their
- forwarding configuration can look like this:
-
- host-a:
-
- forward / .
- forward .isp-b.example.net host-b:8118
-
- host-b:
-
- forward / .
- forward .isp-a.example.org host-a:8118
-
- Now, your users can set their browser's proxy to use either host-a or
- host-b and be able to browse the internal content of both isp-a and isp-b.
-
- If you intend to chain Privoxy and squid locally, then chaining as browser
- -> squid -> privoxy is the recommended way.
-
- Assuming that Privoxy and squid run on the same box, your squid
- configuration could then look like this:
-
- # Define Privoxy as parent proxy (without ICP)
- cache_peer 127.0.0.1 parent 8118 7 no-query
-
- # Define ACL for protocol FTP
- acl ftp proto FTP
-
- # Do not forward FTP requests to Privoxy
- always_direct allow ftp
-
- # Forward all the rest to Privoxy
- never_direct allow all
-
- You would then need to change your browser's proxy settings to squid's
- address and port. Squid normally uses port 3128. If unsure consult
- http_port in squid.conf.
-
- You could just as well decide to only forward requests you suspect of
- leading to Windows executables through a virus-scanning parent proxy, say,
- on antivir.example.com, port 8010:
-
- forward / .
- forward /.*\.(exe|com|dll|zip)$ antivir.example.com:8010
-
- --------------------------------------------------------------------------
-
- 7.5.4. forwarded-connect-retries
-
- Specifies:
-
- How often Privoxy retries if a forwarded connection request fails.
-
- Type of value:
-
- Number of retries.
-
- Default value:
-
- 0
-
- Effect if unset:
-
- Connections forwarded through other proxies are treated like
- direct connections and no retry attempts are made.
-
- Notes:
-
- forwarded-connect-retries is mainly interesting for socks4a
- connections, where Privoxy can't detect why the connections
- failed. The connection might have failed because of a DNS timeout
- in which case a retry makes sense, but it might also have failed
- because the server doesn't exist or isn't reachable. In this case
- the retry will just delay the appearance of Privoxy's error
- message.
-
- Note that in the context of this option, "forwarded connections"
- includes all connections that Privoxy forwards through other
- proxies. This option is not limited to the HTTP CONNECT method.
-
- Only use this option, if you are getting lots of
- forwarding-related error messages that go away when you try again
- manually. Start with a small value and check Privoxy's logfile
- from time to time, to see how many retries are usually needed.
-
- Examples:
-
- forwarded-connect-retries 1
-
- --------------------------------------------------------------------------
-
- 7.5.5. accept-intercepted-requests
-
- Specifies:
-
- Whether intercepted requests should be treated as valid.
-
- Type of value:
-
- 0 or 1
-
- Default value:
-
- 0
-
- Effect if unset:
-
- Only proxy requests are accepted, intercepted requests are treated
- as invalid.
-
- Notes:
-
- If you don't trust your clients and want to force them to use
- Privoxy, enable this option and configure your packet filter to
- redirect outgoing HTTP connections into Privoxy.
-
- Make sure that Privoxy's own requests aren't redirected as well.
- Additionally take care that Privoxy can't intentionally connect to
- itself, otherwise you could run into redirection loops if
- Privoxy's listening port is reachable by the outside or an
- attacker has access to the pages you visit.
-
- Examples:
-
- accept-intercepted-requests 1
-
- --------------------------------------------------------------------------
-
- 7.5.6. allow-cgi-request-crunching
-
- Specifies:
-
- Whether requests to Privoxy's CGI pages can be blocked or
- redirected.
-
- Type of value:
-
- 0 or 1
-
- Default value:
-
- 0
-
- Effect if unset:
-
- Privoxy ignores block and redirect actions for its CGI pages.
-
- Notes:
-
- By default Privoxy ignores block or redirect actions for its CGI
- pages. Intercepting these requests can be useful in multi-user
- setups to implement fine-grained access control, but it can also
- render the complete web interface useless and make debugging
- problems painful if done without care.
-
- Don't enable this option unless you're sure that you really need
- it.
-
- Examples:
-
- allow-cgi-request-crunching 1
-
- --------------------------------------------------------------------------
-
- 7.5.7. split-large-forms
-
- Specifies:
-
- Whether the CGI interface should stay compatible with broken HTTP
- clients.
-
- Type of value:
-
- 0 or 1
-
- Default value:
-
- 0
-
- Effect if unset:
-
- The CGI form generate long GET URLs.
-
- Notes:
-
- Privoxy's CGI forms can lead to rather long URLs. This isn't a
- problem as far as the HTTP standard is concerned, but it can
- confuse clients with arbitrary URL length limitations.
-
- Enabling split-large-forms causes Privoxy to divide big forms into
- smaller ones to keep the URL length down. It makes editing a lot
- less convenient and you can no longer submit all changes at once,
- but at least it works around this browser bug.
-
- If you don't notice any editing problems, there is no reason to
- enable this option, but if one of the submit buttons appears to be
- broken, you should give it a try.
-
- Examples:
-
- split-large-forms 1
-
- --------------------------------------------------------------------------
-
- 7.6. Windows GUI Options
-
- Privoxy has a number of options specific to the Windows GUI interface:
-
- If "activity-animation" is set to 1, the Privoxy icon will animate when
- "Privoxy" is active. To turn off, set to 0.
-
- activity-animation 1
-
-
- If "log-messages" is set to 1, Privoxy will log messages to the console
- window:
-
- log-messages 1
-
-
- If "log-buffer-size" is set to 1, the size of the log buffer, i.e. the
- amount of memory used for the log messages displayed in the console
- window, will be limited to "log-max-lines" (see below).
-
- Warning: Setting this to 0 will result in the buffer to grow infinitely
- and eat up all your memory!
-
- log-buffer-size 1
-
-
- log-max-lines is the maximum number of lines held in the log buffer. See
- above.
-
- log-max-lines 200
-
-
- If "log-highlight-messages" is set to 1, Privoxy will highlight portions
- of the log messages with a bold-faced font:
-
- log-highlight-messages 1
-
-
- The font used in the console window:
-
- log-font-name Comic Sans MS
-
-
- Font size used in the console window:
-
- log-font-size 8
-
-
- "show-on-task-bar" controls whether or not Privoxy will appear as a button
- on the Task bar when minimized:
-
- show-on-task-bar 0
-
-
- If "close-button-minimizes" is set to 1, the Windows close button will
- minimize Privoxy instead of closing the program (close with the exit
- option on the File menu).
-
- close-button-minimizes 1
-
-
- The "hide-console" option is specific to the MS-Win console version of
- Privoxy. If this option is used, Privoxy will disconnect from and hide the
- command console.
-
- #hide-console
-
-
- --------------------------------------------------------------------------
-
-8. Actions Files
-
- The actions files are used to define what actions Privoxy takes for which
- URLs, and thus determines how ad images, cookies and various other aspects
- of HTTP content and transactions are handled, and on which sites (or even
- parts thereof). There are a number of such actions, with a wide range of
- functionality. Each action does something a little different. These
- actions give us a veritable arsenal of tools with which to exert our
- control, preferences and independence. Actions can be combined so that
- their effects are aggregated when applied against a given set of URLs.
-
- There are three action files included with Privoxy with differing
- purposes:
-
- * default.action - is the primary action file that sets the initial
- values for all actions. It is intended to provide a base level of
- functionality for Privoxy's array of features. So it is a set of broad
- rules that should work reasonably well as-is for most users. This is
- the file that the developers are keeping updated, and making available
- to users. The user's preferences as set in standard.action, e.g.
- either Cautious (the default), Medium, or Advanced (see below).
-
- * user.action - is intended to be for local site preferences and
- exceptions. As an example, if your ISP or your bank has specific
- requirements, and need special handling, this kind of thing should go
- here. This file will not be upgraded.
-
- * standard.action - is used only by the web based editor at
- http://config.privoxy.org/edit-actions-list?f=default, to set various
- pre-defined sets of rules for the default actions section in
- default.action.
-
- Edit Set to Cautious Set to Medium Set to Advanced
-
- These have increasing levels of aggressiveness and have no influence
- on your browsing unless you select them explicitly in the editor. A
- default installation should be pre-set to Cautious (versions prior to
- 3.0.5 were set to Medium). New users should try this for a while
- before adjusting the settings to more aggressive levels. The more
- aggressive the settings, then the more likelihood there is of problems
- such as sites not working as they should.
-
- The Edit button allows you to turn each action on/off individually for
- fine-tuning. The Cautious button changes the actions list to low/safe
- settings which will activate ad blocking and a minimal set of
- Privoxy's features, and subsequently there will be less of a chance
- for accidental problems. The Medium button sets the list to a medium
- level of other features and a low level set of privacy features. The
- Advanced button sets the list to a high level of ad blocking and
- medium level of privacy. See the chart below. The latter three buttons
- over-ride any changes via with the Edit button. More fine-tuning can
- be done in the lower sections of this internal page.
-
- It is not recommend to edit the standard.action file itself.
-
- The default profiles, and their associated actions, as pre-defined in
- standard.action are:
-
- Table 1. Default Configurations
-
- +--------------------------------------------------------------------+
- | Feature | Cautious | Medium | Advanced |
- |-------------------------+-------------+--------------+-------------|
- | Ad-blocking | medium | high | high |
- | Aggressiveness | | | |
- |-------------------------+-------------+--------------+-------------|
- | Ad-filtering by size | no | yes | yes |
- |-------------------------+-------------+--------------+-------------|
- | Ad-filtering by link | no | no | yes |
- |-------------------------+-------------+--------------+-------------|
- | Pop-up killing | blocks only | blocks only | blocks only |
- |-------------------------+-------------+--------------+-------------|
- | Privacy Features | low | medium | medium/high |
- |-------------------------+-------------+--------------+-------------|
- | Cookie handling | none | session-only | kill |
- |-------------------------+-------------+--------------+-------------|
- | Referer forging | no | yes | yes |
- |-------------------------+-------------+--------------+-------------|
- | GIF de-animation | no | yes | yes |
- |-------------------------+-------------+--------------+-------------|
- | Fast redirects | no | no | yes |
- |-------------------------+-------------+--------------+-------------|
- | HTML taming | no | no | yes |
- |-------------------------+-------------+--------------+-------------|
- | JavaScript taming | no | no | yes |
- |-------------------------+-------------+--------------+-------------|
- | Web-bug killing | no | yes | yes |
- |-------------------------+-------------+--------------+-------------|
- | Image tag reordering | no | no | yes |
- +--------------------------------------------------------------------+
-
- The list of actions files to be used are defined in the main configuration
- file, and are processed in the order they are defined (e.g. default.action
- is typically processed before user.action). The content of these can all
- be viewed and edited from http://config.privoxy.org/show-status. The
- over-riding principle when applying actions, is that the last action that
- matches a given URL wins. The broadest, most general rules go first
- (defined in default.action), followed by any exceptions (typically also in
- default.action), which are then followed lastly by any local preferences
- (typically in user.action). Generally, user.action has the last word.
-
- An actions file typically has multiple sections. If you want to use
- "aliases" in an actions file, you have to place the (optional) alias
- section at the top of that file. Then comes the default set of rules which
- will apply universally to all sites and pages (be very careful with using
- such a universal set in user.action or any other actions file after
- default.action, because it will override the result from consulting any
- previous file). And then below that, exceptions to the defined universal
- policies. You can regard user.action as an appendix to default.action,
- with the advantage that it is a separate file, which makes preserving your
- personal settings across Privoxy upgrades easier.
-
- Actions can be used to block anything you want, including ads, banners, or
- just some obnoxious URL whose content you would rather not see. Cookies
- can be accepted or rejected, or accepted only during the current browser
- session (i.e. not written to disk), content can be modified, some
- JavaScripts tamed, user-tracking fooled, and much more. See below for a
- complete list of actions.
-
- --------------------------------------------------------------------------
-
- 8.1. Finding the Right Mix
-
- Note that some actions, like cookie suppression or script disabling, may
- render some sites unusable that rely on these techniques to work properly.
- Finding the right mix of actions is not always easy and certainly a matter
- of personal taste. And, things can always change, requiring refinements in
- the configuration. In general, it can be said that the more "aggressive"
- your default settings (in the top section of the actions file) are, the
- more exceptions for "trusted" sites you will have to make later. If, for
- example, you want to crunch all cookies per default, you'll have to make
- exceptions from that rule for sites that you regularly use and that
- require cookies for actually useful purposes, like maybe your bank,
- favorite shop, or newspaper.
-
- We have tried to provide you with reasonable rules to start from in the
- distribution actions files. But there is no general rule of thumb on these
- things. There just are too many variables, and sites are constantly
- changing. Sooner or later you will want to change the rules (and read this
- chapter again :).
-
- --------------------------------------------------------------------------
-
- 8.2. How to Edit
-
- The easiest way to edit the actions files is with a browser by using our
- browser-based editor, which can be reached from
- http://config.privoxy.org/show-status. Note: the config file option
- enable-edit-actions must be enabled for this to work. The editor allows
- both fine-grained control over every single feature on a per-URL basis,
- and easy choosing from wholesale sets of defaults like "Cautious",
- "Medium" or "Advanced". Warning: the "Advanced" setting is more
- aggressive, and will be more likely to cause problems for some sites.
- Experienced users only!
-
- If you prefer plain text editing to GUIs, you can of course also directly
- edit the the actions files with your favorite text editor. Look at
- default.action which is richly commented with many good examples.
-
- --------------------------------------------------------------------------
-
- 8.3. How Actions are Applied to Requests
-
- Actions files are divided into sections. There are special sections, like
- the "alias" sections which will be discussed later. For now let's
- concentrate on regular sections: They have a heading line (often split up
- to multiple lines for readability) which consist of a list of actions,
- separated by whitespace and enclosed in curly braces. Below that, there is
- a list of URL and tag patterns, each on a separate line.
-
- To determine which actions apply to a request, the URL of the request is
- compared to all URL patterns in each "action file". Every time it matches,
- the list of applicable actions for the request is incrementally updated,
- using the heading of the section in which the pattern is located. The same
- is done again for tags and tag patterns later on.
-
- If multiple applying sections set the same action differently, the last
- match wins. If not, the effects are aggregated. E.g. a URL might match a
- regular section with a heading line of { +handle-as-image }, then later
- another one with just { +block }, resulting in both actions to apply. And
- there may well be cases where you will want to combine actions together.
- Such a section then might look like:
-
- { +handle-as-image +block }
- # Block these as if they were images. Send no block page.
- banners.example.com
- media.example.com/.*banners
- .example.com/images/ads/
-
- You can trace this process for URL patterns and any given URL by visiting
- http://config.privoxy.org/show-url-info.
-
- Examples and more detail on this is provided in the Appendix,
- Troubleshooting: Anatomy of an Action section.
-
- --------------------------------------------------------------------------
-
- 8.4. Patterns
-
- As mentioned, Privoxy uses "patterns" to determine what actions might
- apply to which sites and pages your browser attempts to access. These
- "patterns" use wild card type pattern matching to achieve a high degree of
- flexibility. This allows one expression to be expanded and potentially
- match against many similar patterns.
-
- Generally, an URL pattern has the form <domain>/<path>, where both the
- <domain> and <path> are optional. (This is why the special / pattern
- matches all URLs). Note that the protocol portion of the URL pattern (e.g.
- http://) should not be included in the pattern. This is assumed already!
-
- The pattern matching syntax is different for the domain and path parts of
- the URL. The domain part uses a simple globbing type matching technique,
- while the path part uses a more flexible "Regular Expressions (PCRE)"
- based syntax.
-
- www.example.com/
-
- is a domain-only pattern and will match any request to
- www.example.com, regardless of which document on that server is
- requested. So ALL pages in this domain would be covered by the
- scope of this action. Note that a simple example.com is different
- and would NOT match.
-
- www.example.com
-
- means exactly the same. For domain-only patterns, the trailing /
- may be omitted.
-
- www.example.com/index.html$
-
- matches all the documents on www.example.com whose name starts
- with /index.html.
-
- www.example.com/index.html$
-
- matches only the single document /index.html on www.example.com.
-
- /index.html$
-
- matches the document /index.html, regardless of the domain, i.e.
- on any web server anywhere.
-
- index.html
-
- matches nothing, since it would be interpreted as a domain name
- and there is no top-level domain called .html. So its a mistake.
-
- --------------------------------------------------------------------------
-
- 8.4.1. The Domain Pattern
-
- The matching of the domain part offers some flexible options: if the
- domain starts or ends with a dot, it becomes unanchored at that end. For
- example:
-
- .example.com
-
- matches any domain with first-level domain com and second-level
- domain example. For example www.example.com, example.com and
- foo.bar.baz.example.com. Note that it wouldn't match if the
- second-level domain was another-example.
-
- www.
-
- matches any domain that STARTS with www. (It also matches the
- domain www but most of the time that doesn't matter.)
-
- .example.
-
- matches any domain that CONTAINS .example.. And, by the way, also
- included would be any files or documents that exist within that
- domain since no path limitations are specified. (Correctly
- speaking: It matches any FQDN that contains example as a domain.)
- This might be www.example.com, news.example.de, or
- www.example.net/cgi/testing.pl for instance. All these cases are
- matched.
-
- Additionally, there are wild-cards that you can use in the domain names
- themselves. These work similarly to shell globbing type wild-cards: "*"
- represents zero or more arbitrary characters (this is equivalent to the
- "Regular Expression" based syntax of ".*"), "?" represents any single
- character (this is equivalent to the regular expression syntax of a simple
- "."), and you can define "character classes" in square brackets which is
- similar to the same regular expression technique. All of this can be
- freely mixed:
-
- ad*.example.com
-
- matches "adserver.example.com", "ads.example.com", etc but not
- "sfads.example.com"
-
- *ad*.example.com
-
- matches all of the above, and then some.
-
- .?pix.com
-
- matches www.ipix.com, pictures.epix.com, a.b.c.d.e.upix.com etc.
-
- www[1-9a-ez].example.c*
-
- matches www1.example.com, www4.example.cc, wwwd.example.cy,
- wwwz.example.com etc., but not wwww.example.com.
-
- While flexible, this is not the sophistication of full regular expression
- based syntax.
-
- --------------------------------------------------------------------------
-
- 8.4.2. The Path Pattern
-
- Privoxy uses Perl compatible (PCRE) "Regular Expression" based syntax
- (through the PCRE library) for matching the path portion (after the
- slash), and is thus more flexible.
-
- There is an Appendix with a brief quick-start into regular expressions,
- and full (very technical) documentation on PCRE regex syntax is available
- on-line at http://www.pcre.org/man.txt. You might also find the Perl man
- page on regular expressions (man perlre) useful, which is available
- on-line at http://perldoc.perl.org/perlre.html.
-
- Note that the path pattern is automatically left-anchored at the "/", i.e.
- it matches as if it would start with a "^" (regular expression speak for
- the beginning of a line).
-
- Please also note that matching in the path is CASE INSENSITIVE by default,
- but you can switch to case sensitive at any point in the pattern by using
- the "(?-i)" switch: www.example.com/(?-i)PaTtErN.* will match only
- documents whose path starts with PaTtErN in exactly this capitalization.
-
- .example.com/.*
-
- Is equivalent to just ".example.com", since any documents within
- that domain are matched with or without the ".*" regular
- expression. This is redundant
-
- .example.com/.*/index.html$
-
- Will match any page in the domain of "example.com" that is named
- "index.html", and that is part of some path. For example, it
- matches "www.example.com/testing/index.html" but NOT
- "www.example.com/index.html" because the regular expression called
- for at least two "/'s", thus the path requirement. It also would
- match "www.example.com/testing/index_html", because of the special
- meta-character ".".
-
- .example.com/(.*/)?index\.html$
-
- This regular expression is conditional so it will match any page
- named "index.html" regardless of path which in this case can have
- one or more "/'s". And this one must contain exactly ".html" (but
- does not have to end with that!).
-
- .example.com/(.*/)(ads|banners?|junk)
-
- This regular expression will match any path of "example.com" that
- contains any of the words "ads", "banner", "banners" (because of
- the "?") or "junk". The path does not have to end in these words,
- just contain them.
-
- .example.com/(.*/)(ads|banners?|junk)/.*\.(jpe?g|gif|png)$
-
- This is very much the same as above, except now it must end in
- either ".jpg", ".jpeg", ".gif" or ".png". So this one is limited
- to common image formats.
-
- There are many, many good examples to be found in default.action, and more
- tutorials below in Appendix on regular expressions.
-
- --------------------------------------------------------------------------
-
- 8.4.3. The Tag Pattern
-
- Tag patterns are used to change the applying actions based on the
- request's tags. Tags can be created with either the client-header-tagger
- or the server-header-tagger action.
-
- Tag patterns have to start with "TAG:", so Privoxy can tell them apart
- from URL patterns. Everything after the colon including white space, is
- interpreted as a regular expression with path pattern syntax, except that
- tag patterns aren't left-anchored automatically (Privoxy doesn't silently
- add a "^", you have to do it yourself if you need it).
-
- To match all requests that are tagged with "foo" your pattern line should
- be "TAG:^foo$", "TAG:foo" would work as well, but it would also match
- requests whose tags contain "foo" somewhere. "TAG: foo" wouldn't work as
- it requires white space.
-
- Sections can contain URL and tag patterns at the same time, but tag
- patterns are checked after the URL patterns and thus always overrule them,
- even if they are located before the URL patterns.
-
- Once a new tag is added, Privoxy checks right away if it's matched by one
- of the tag patterns and updates the action settings accordingly. As a
- result tags can be used to activate other tagger actions, as long as these
- other taggers look for headers that haven't already be parsed.
-
- For example you could tag client requests which use the POST method, then
- use this tag to activate another tagger that adds a tag if cookies are
- sent, and then use a block action based on the cookie tag. This allows the
- outcome of one action, to be input into a subsequent action. However if
- you'd reverse the position of the described taggers, and activated the
- method tagger based on the cookie tagger, no method tags would be created.
- The method tagger would look for the request line, but at the time the
- cookie tag is created, the request line has already been parsed.
-
- While this is a limitation you should be aware of, this kind of
- indirection is seldom needed anyway and even the example doesn't make too
- much sense.
-
- --------------------------------------------------------------------------
-
- 8.5. Actions
-
- All actions are disabled by default, until they are explicitly enabled
- somewhere in an actions file. Actions are turned on if preceded with a
- "+", and turned off if preceded with a "-". So a +action means "do that
- action", e.g. +block means "please block URLs that match the following
- patterns", and -block means "don't block URLs that match the following
- patterns, even if +block previously applied."
-
- Again, actions are invoked by placing them on a line, enclosed in curly
- braces and separated by whitespace, like in {+some-action
- -some-other-action{some-parameter}}, followed by a list of URL patterns,
- one per line, to which they apply. Together, the actions line and the
- following pattern lines make up a section of the actions file.
-
- Actions fall into three categories:
-
- * Boolean, i.e the action can only be "enabled" or "disabled". Syntax:
-
- +name # enable action name
- -name # disable action name
-
- Example: +block
-
- * Parameterized, where some value is required in order to enable this
- type of action. Syntax:
-
- +name{param} # enable action and set parameter to param,
- # overwriting parameter from previous match if necessary
- -name # disable action. The parameter can be omitted
-
- Note that if the URL matches multiple positive forms of a
- parameterized action, the last match wins, i.e. the params from
- earlier matches are simply ignored.
-
- Example: +hide-user-agent{Mozilla/5.0 (X11; U; FreeBSD i386; en-US;
- rv:1.8.1.4) Gecko/20070602 Firefox/2.0.0.4}
-
- * Multi-value. These look exactly like parameterized actions, but they
- behave differently: If the action applies multiple times to the same
- URL, but with different parameters, all the parameters from all
- matches are remembered. This is used for actions that can be executed
- for the same request repeatedly, like adding multiple headers, or
- filtering through multiple filters. Syntax:
-
- +name{param} # enable action and add param to the list of parameters
- -name{param} # remove the parameter param from the list of parameters
- # If it was the last one left, disable the action.
- -name # disable this action completely and remove all parameters from the list
-
- Examples: +add-header{X-Fun-Header: Some text} and
- +filter{html-annoyances}
-
- If nothing is specified in any actions file, no "actions" are taken. So in
- this case Privoxy would just be a normal, non-blocking, non-filtering
- proxy. You must specifically enable the privacy and blocking features you
- need (although the provided default actions files will give a good
- starting point).
-
- Later defined action sections always over-ride earlier ones of the same
- type. So exceptions to any rules you make, should come in the latter part
- of the file (or in a file that is processed later when using multiple
- actions files such as user.action). For multi-valued actions, the actions
- are applied in the order they are specified. Actions files are processed
- in the order they are defined in config (the default installation has
- three actions files). It also quite possible for any given URL to match
- more than one "pattern" (because of wildcards and regular expressions),
- and thus to trigger more than one set of actions! Last match wins.
-
- The list of valid Privoxy actions are:
-
- --------------------------------------------------------------------------
-
- 8.5.1. add-header
-
- Typical use:
-
- Confuse log analysis, custom applications
-
- Effect:
-
- Sends a user defined HTTP header to the web server.
-
- Type:
-
- Multi-value.
-
- Parameter:
-
- Any string value is possible. Validity of the defined HTTP headers
- is not checked. It is recommended that you use the "X-" prefix for
- custom headers.
-
- Notes:
-
- This action may be specified multiple times, in order to define
- multiple headers. This is rarely needed for the typical user. If
- you don't know what "HTTP headers" are, you definitely don't need
- to worry about this one.
-
- Example usage:
-
- +add-header{X-User-Tracking: sucks}
-
- --------------------------------------------------------------------------
-
- 8.5.2. block
-
- Typical use:
-
- Block ads or other unwanted content
-
- Effect:
-
- Requests for URLs to which this action applies are blocked, i.e.
- the requests are trapped by Privoxy and the requested URL is never
- retrieved, but is answered locally with a substitute page or
- image, as determined by the handle-as-image, set-image-blocker,
- and handle-as-empty-document actions.
-
- Type:
-
- Boolean.
-
- Parameter:
-
- N/A
-
- Notes:
-
- Privoxy sends a special "BLOCKED" page for requests to blocked
- pages. This page contains links to find out why the request was
- blocked, and a click-through to the blocked content (the latter
- only if compiled with the force feature enabled). The "BLOCKED"
- page adapts to the available screen space -- it displays
- full-blown if space allows, or miniaturized and text-only if
- loaded into a small frame or window. If you are using Privoxy
- right now, you can take a look at the "BLOCKED" page.
-
- A very important exception occurs if both block and
- handle-as-image, apply to the same request: it will then be
- replaced by an image. If set-image-blocker (see below) also
- applies, the type of image will be determined by its parameter, if
- not, the standard checkerboard pattern is sent.
-
- It is important to understand this process, in order to understand
- how Privoxy deals with ads and other unwanted content. Blocking is
- a core feature, and one upon which various other features depend.
-
- The filter action can perform a very similar task, by "blocking"
- banner images and other content through rewriting the relevant
- URLs in the document's HTML source, so they don't get requested in
- the first place. Note that this is a totally different technique,
- and it's easy to confuse the two.
-
- Example usage (section):
-
- {+block}
- # Block and replace with "blocked" page
- .nasty-stuff.example.com
-
- {+block +handle-as-image}
- # Block and replace with image
- .ad.doubleclick.net
- .ads.r.us/banners/
-
- {+block +handle-as-empty-document}
- # Block and then ignore
- adserver.exampleclick.net/.*\.js$
-
- --------------------------------------------------------------------------
-
- 8.5.3. client-header-filter
-
- Typical use:
-
- Rewrite or remove single client headers.
-
- Effect:
-
- All client headers to which this action applies are filtered
- on-the-fly through the specified regular expression based
- substitutions.
-
- Type:
-
- Parameterized.
-
- Parameter:
-
- The name of a client-header filter, as defined in one of the
- filter files.
-
- Notes:
-
- Client-header filters are applied to each header on its own, not
- to all at once. This makes it easier to diagnose problems, but on
- the downside you can't write filters that only change header x if
- header y's value is z. You can do that by using tags though.
-
- Client-header filters are executed after the other header actions
- have finished and use their output as input.
-
- If the request URL gets changed, Privoxy will detect that and use
- the new one. This can be used to rewrite the request destination
- behind the client's back, for example to specify a Tor exit relay
- for certain requests.
-
- Please refer to the filter file chapter to learn which
- client-header filters are available by default, and how to create
- your own.
-
- Example usage (section):
-
- {+client-header-filter{hide-tor-exit-notation}}
- .exit/
-
-
- --------------------------------------------------------------------------
-
- 8.5.4. client-header-tagger
-
- Typical use:
-
- Block requests based on their headers.
-
- Effect:
-
- Client headers to which this action applies are filtered
- on-the-fly through the specified regular expression based
- substitutions, the result is used as tag.
-
- Type:
-
- Parameterized.
-
- Parameter:
-
- The name of a client-header tagger, as defined in one of the
- filter files.
-
- Notes:
-
- Client-header taggers are applied to each header on its own, and
- as the header isn't modified, each tagger "sees" the original.
-
- Client-header taggers are the first actions that are executed and
- their tags can be used to control every other action.
-
- Example usage (section):
-
- # Tag every request with the User-Agent header
- {+client-header-tagger{user-agent}}
- /
-
-
- --------------------------------------------------------------------------
-
- 8.5.5. content-type-overwrite
-
- Typical use:
-
- Stop useless download menus from popping up, or change the
- browser's rendering mode
-
- Effect:
-
- Replaces the "Content-Type:" HTTP server header.
-
- Type:
-
- Parameterized.
-
- Parameter:
-
- Any string.
-
- Notes:
-
- The "Content-Type:" HTTP server header is used by the browser to
- decide what to do with the document. The value of this header can
- cause the browser to open a download menu instead of displaying
- the document by itself, even if the document's format is supported
- by the browser.
-
- The declared content type can also affect which rendering mode the
- browser chooses. If XHTML is delivered as "text/html", many
- browsers treat it as yet another broken HTML document. If it is
- send as "application/xml", browsers with XHTML support will only
- display it, if the syntax is correct.
-
- If you see a web site that proudly uses XHTML buttons, but sets
- "Content-Type: text/html", you can use Privoxy to overwrite it
- with "application/xml" and validate the web master's claim inside
- your XHTML-supporting browser. If the syntax is incorrect, the
- browser will complain loudly.
-
- You can also go the opposite direction: if your browser prints
- error messages instead of rendering a document falsely declared as
- XHTML, you can overwrite the content type with "text/html" and
- have it rendered as broken HTML document.
-
- By default content-type-overwrite only replaces "Content-Type:"
- headers that look like some kind of text. If you want to overwrite
- it unconditionally, you have to combine it with force-text-mode.
- This limitation exists for a reason, think twice before
- circumventing it.
-
- Most of the time it's easier to replace this action with a custom
- server-header filter. It allows you to activate it for every
- document of a certain site and it will still only replace the
- content types you aimed at.
-
- Of course you can apply content-type-overwrite to a whole site and
- then make URL based exceptions, but it's a lot more work to get
- the same precision.
-
- Example usage (sections):
-
- # Check if www.example.net/ really uses valid XHTML
- { +content-type-overwrite{application/xml} }
- www.example.net/
-
- # but leave the content type unmodified if the URL looks like a style sheet
- {-content-type-overwrite}
- www.example.net/.*\.css$
- www.example.net/.*style
-
- --------------------------------------------------------------------------
-
- 8.5.6. crunch-client-header
-
- Typical use:
-
- Remove a client header Privoxy has no dedicated action for.
-
- Effect:
-
- Deletes every header sent by the client that contains the string
- the user supplied as parameter.
-
- Type:
-
- Parameterized.
-
- Parameter:
-
- Any string.
-
- Notes:
-
- This action allows you to block client headers for which no
- dedicated Privoxy action exists. Privoxy will remove every client
- header that contains the string you supplied as parameter.
-
- Regular expressions are not supported and you can't use this
- action to block different headers in the same request, unless they
- contain the same string.
-
- crunch-client-header is only meant for quick tests. If you have to
- block several different headers, or only want to modify parts of
- them, you should use a client-header filter.
-
- +---------------------------------------------------------+
- | Warning |
- |---------------------------------------------------------|
- | Don't block any header without understanding the |
- | consequences. |
- +---------------------------------------------------------+
-
- Example usage (section):
-
- # Block the non-existent "Privacy-Violation:" client header
- { +crunch-client-header{Privacy-Violation:} }
- /
-
-
- --------------------------------------------------------------------------
-
- 8.5.7. crunch-if-none-match
-
- Typical use:
-
- Prevent yet another way to track the user's steps between
- sessions.
-
- Effect:
-
- Deletes the "If-None-Match:" HTTP client header.
-
- Type:
-
- Boolean.
-
- Parameter:
-
- N/A
-
- Notes:
-
- Removing the "If-None-Match:" HTTP client header is useful for
- filter testing, where you want to force a real reload instead of
- getting status code "304" which would cause the browser to use a
- cached copy of the page.
-
- It is also useful to make sure the header isn't used as a cookie
- replacement (unlikely but possible).
-
- Blocking the "If-None-Match:" header shouldn't cause any caching
- problems, as long as the "If-Modified-Since:" header isn't blocked
- or missing as well.
-
- It is recommended to use this action together with
- hide-if-modified-since and overwrite-last-modified.
-
- Example usage (section):
-
- # Let the browser revalidate cached documents but don't
- # allow the server to use the revalidation headers for user tracking.
- {+hide-if-modified-since{-60} \
- +overwrite-last-modified{randomize} \
- +crunch-if-none-match}
- /
-
- --------------------------------------------------------------------------
-
- 8.5.8. crunch-incoming-cookies
-
- Typical use:
-
- Prevent the web server from setting HTTP cookies on your system
-
- Effect:
-
- Deletes any "Set-Cookie:" HTTP headers from server replies.
-
- Type:
-
- Boolean.
-
- Parameter:
-
- N/A
-
- Notes:
-
- This action is only concerned with incoming HTTP cookies. For
- outgoing HTTP cookies, use crunch-outgoing-cookies. Use both to
- disable HTTP cookies completely.
-
- It makes no sense at all to use this action in conjunction with
- the session-cookies-only action, since it would prevent the
- session cookies from being set. See also filter-content-cookies.
-
- Example usage:
-
- +crunch-incoming-cookies
-
- --------------------------------------------------------------------------
-
- 8.5.9. crunch-server-header
-
- Typical use:
-
- Remove a server header Privoxy has no dedicated action for.
-
- Effect:
-
- Deletes every header sent by the server that contains the string
- the user supplied as parameter.
-
- Type:
-
- Parameterized.
-
- Parameter:
-
- Any string.
-
- Notes:
-
- This action allows you to block server headers for which no
- dedicated Privoxy action exists. Privoxy will remove every server
- header that contains the string you supplied as parameter.
-
- Regular expressions are not supported and you can't use this
- action to block different headers in the same request, unless they
- contain the same string.
-
- crunch-server-header is only meant for quick tests. If you have to
- block several different headers, or only want to modify parts of
- them, you should use a custom server-header filter.
-
- +---------------------------------------------------------+
- | Warning |
- |---------------------------------------------------------|
- | Don't block any header without understanding the |
- | consequences. |
- +---------------------------------------------------------+
-
- Example usage (section):
-
- # Crunch server headers that try to prevent caching
- { +crunch-server-header{no-cache} }
- /
-
- --------------------------------------------------------------------------
-
- 8.5.10. crunch-outgoing-cookies
-
- Typical use:
-
- Prevent the web server from reading any HTTP cookies from your
- system
-
- Effect:
-
- Deletes any "Cookie:" HTTP headers from client requests.
-
- Type:
-
- Boolean.
-
- Parameter:
-
- N/A
-
- Notes:
-
- This action is only concerned with outgoing HTTP cookies. For
- incoming HTTP cookies, use crunch-incoming-cookies. Use both to
- disable HTTP cookies completely.
-
- It makes no sense at all to use this action in conjunction with
- the session-cookies-only action, since it would prevent the
- session cookies from being read.
-
- Example usage:
-
- +crunch-outgoing-cookies
-
- --------------------------------------------------------------------------
-
- 8.5.11. deanimate-gifs
-
- Typical use:
-
- Stop those annoying, distracting animated GIF images.
-
- Effect:
-
- De-animate GIF animations, i.e. reduce them to their first or last
- image.
-
- Type:
-
- Parameterized.
-
- Parameter:
-
- "last" or "first"
-
- Notes:
-
- This will also shrink the images considerably (in bytes, not
- pixels!). If the option "first" is given, the first frame of the
- animation is used as the replacement. If "last" is given, the last
- frame of the animation is used instead, which probably makes more
- sense for most banner animations, but also has the risk of not
- showing the entire last frame (if it is only a delta to an earlier
- frame).
-
- You can safely use this action with patterns that will also match
- non-GIF objects, because no attempt will be made at anything that
- doesn't look like a GIF.
-
- Example usage:
-
- +deanimate-gifs{last}
-
- --------------------------------------------------------------------------
-
- 8.5.12. downgrade-http-version
-
- Typical use:
-
- Work around (very rare) problems with HTTP/1.1
-
- Effect:
-
- Downgrades HTTP/1.1 client requests and server replies to
- HTTP/1.0.
-
- Type:
-
- Boolean.
-
- Parameter:
-
- N/A
-
- Notes:
-
- This is a left-over from the time when Privoxy didn't support
- important HTTP/1.1 features well. It is left here for the unlikely
- case that you experience HTTP/1.1 related problems with some
- server out there. Not all HTTP/1.1 features and requirements are
- supported yet, so there is a chance you might need this action.
-
- Example usage (section):
-
- {+downgrade-http-version}
- problem-host.example.com
-
- --------------------------------------------------------------------------
-
- 8.5.13. fast-redirects
-
- Typical use:
-
- Fool some click-tracking scripts and speed up indirect links.
-
- Effect:
-
- Detects redirection URLs and redirects the browser without
- contacting the redirection server first.
-
- Type:
-
- Parameterized.
-
- Parameter:
-
- * "simple-check" to just search for the string "http://" to
- detect redirection URLs.
-
- * "check-decoded-url" to decode URLs (if necessary) before
- searching for redirection URLs.
-
- Notes:
-
- Many sites, like yahoo.com, don't just link to other sites.
- Instead, they will link to some script on their own servers,
- giving the destination as a parameter, which will then redirect
- you to the final target. URLs resulting from this scheme typically
- look like:
- "http://www.example.org/click-tracker.cgi?target=http%3a//www.example.net/".
-
- Sometimes, there are even multiple consecutive redirects encoded
- in the URL. These redirections via scripts make your web browsing
- more traceable, since the server from which you follow such a link
- can see where you go to. Apart from that, valuable bandwidth and
- time is wasted, while your browser asks the server for one
- redirect after the other. Plus, it feeds the advertisers.
-
- This feature is currently not very smart and is scheduled for
- improvement. If it is enabled by default, you will have to create
- some exceptions to this action. It can lead to failures in several
- ways:
-
- Not every URLs with other URLs as parameters is evil. Some sites
- offer a real service that requires this information to work. For
- example a validation service needs to know, which document to
- validate. fast-redirects assumes that every URL parameter that
- looks like another URL is a redirection target, and will always
- redirect to the last one. Most of the time the assumption is
- correct, but if it isn't, the user gets redirected anyway.
-
- Another failure occurs if the URL contains other parameters after
- the URL parameter. The URL:
- "http://www.example.org/?redirect=http%3a//www.example.net/&foo=bar".
- contains the redirection URL "http://www.example.net/", followed
- by another parameter. fast-redirects doesn't know that and will
- cause a redirect to "http://www.example.net/&foo=bar". Depending
- on the target server configuration, the parameter will be silently
- ignored or lead to a "page not found" error. You can prevent this
- problem by first using the redirect action to remove the last part
- of the URL, but it requires a little effort.
-
- To detect a redirection URL, fast-redirects only looks for the
- string "http://", either in plain text (invalid but often used) or
- encoded as "http%3a//". Some sites use their own URL encoding
- scheme, encrypt the address of the target server or replace it
- with a database id. In theses cases fast-redirects is fooled and
- the request reaches the redirection server where it probably gets
- logged.
-
- Example usage:
-
- { +fast-redirects{simple-check} }
- one.example.com
-
- { +fast-redirects{check-decoded-url} }
- another.example.com/testing
-
- --------------------------------------------------------------------------
-
- 8.5.14. filter
-
- Typical use:
-
- Get rid of HTML and JavaScript annoyances, banner advertisements
- (by size), do fun text replacements, add personalized effects,
- etc.
-
- Effect:
-
- All instances of text-based type, most notably HTML and
- JavaScript, to which this action applies, can be filtered
- on-the-fly through the specified regular expression based
- substitutions. (Note: as of version 3.0.3 plain text documents are
- exempted from filtering, because web servers often use the
- text/plain MIME type for all files whose type they don't know.)
-
- Type:
-
- Parameterized.
-
- Parameter:
-
- The name of a content filter, as defined in the filter file.
- Filters can be defined in one or more files as defined by the
- filterfile option in the config file. default.filter is the
- collection of filters supplied by the developers. Locally defined
- filters should go in their own file, such as user.filter.
-
- When used in its negative form, and without parameters, all
- filtering is completely disabled.
-
- Notes:
-
- For your convenience, there are a number of pre-defined filters
- available in the distribution filter file that you can use. See
- the examples below for a list.
-
- Filtering requires buffering the page content, which may appear to
- slow down page rendering since nothing is displayed until all
- content has passed the filters. (It does not really take longer,
- but seems that way since the page is not incrementally displayed.)
- This effect will be more noticeable on slower connections.
-
- "Rolling your own" filters requires a knowledge of "Regular
- Expressions" and "HTML". This is very powerful feature, and
- potentially very intrusive. Filters should be used with caution,
- and where an equivalent "action" is not available.
-
- The amount of data that can be filtered is limited to the
- buffer-limit option in the main config file. The default is 4096
- KB (4 Megs). Once this limit is exceeded, the buffered data, and
- all pending data, is passed through unfiltered.
-
- Inappropriate MIME types, such as zipped files, are not filtered
- at all. (Again, only text-based types except plain text).
- Encrypted SSL data (from HTTPS servers) cannot be filtered either,
- since this would violate the integrity of the secure transaction.
- In some situations it might be necessary to protect certain text,
- like source code, from filtering by defining appropriate -filter
- exceptions.
-
- Compressed content can't be filtered either, unless Privoxy is
- compiled with zlib support (requires at least Privoxy 3.0.7), in
- which case Privoxy will decompress the content before filtering
- it.
-
- If you use a Privoxy version without zlib support, but want
- filtering to work on as much documents as possible, even those
- that would normally be sent compressed, you must use the
- prevent-compression action in conjunction with filter.
-
- Content filtering can achieve some of the same effects as the
- block action, i.e. it can be used to block ads and banners. But
- the mechanism works quite differently. One effective use, is to
- block ad banners based on their size (see below), since many of
- these seem to be somewhat standardized.
-
- Feedback with suggestions for new or improved filters is
- particularly welcome!
-
- The below list has only the names and a one-line description of
- each predefined filter. There are more verbose explanations of
- what these filters do in the filter file chapter.
-
- Example usage (with filters from the distribution default.filter file).
- See the Predefined Filters section for more explanation on each:
-
-+filter{js-annoyances} # Get rid of particularly annoying JavaScript abuse
-
-+filter{js-events} # Kill all JS event bindings (Radically destructive! Only for extra nasty sites)
-
- +filter{html-annoyances} # Get rid of particularly annoying HTML abuse
-
- +filter{content-cookies} # Kill cookies that come in the HTML or JS content
-
-+filter{refresh-tags} # Kill automatic refresh tags (for dial-on-demand setups)
-
-+filter{unsolicited-popups} # Disable only unsolicited pop-up windows. Useful if your browser lacks this ability.
-
-+filter{all-popups} # Kill all popups in JavaScript and HTML. Useful if your browser lacks this ability.
-
-+filter{img-reorder} # Reorder attributes in <img> tags to make the banners-by-* filters more effective
-
- +filter{banners-by-size} # Kill banners by size
-
-+filter{banners-by-link} # Kill banners by their links to known clicktrackers
-
-+filter{webbugs} # Squish WebBugs (1x1 invisible GIFs used for user tracking)
-
-+filter{tiny-textforms} # Extend those tiny textareas up to 40x80 and kill the hard wrap
-
-+filter{jumping-windows} # Prevent windows from resizing and moving themselves
-
- +filter{frameset-borders} # Give frames a border and make them resizeable
-
- +filter{demoronizer} # Fix MS's non-standard use of standard charsets
-
- +filter{shockwave-flash} # Kill embedded Shockwave Flash objects
-
- +filter{quicktime-kioskmode} # Make Quicktime movies savable
-
- +filter{fun} # Text replacements for subversive browsing fun!
-
- +filter{crude-parental} # Crude parental filtering (demo only)
-
- +filter{ie-exploits} # Disable a known Internet Explorer bug exploits
-
-+filter{site-specifics} # Custom filters for specific site related problems
-
-+filter{google} # Removes text ads and other Google specific improvements
-
-+filter{yahoo} # Removes text ads and other Yahoo specific improvements
-
-+filter{msn} # Removes text ads and other MSN specific improvements
-
- +filter{blogspot} # Cleans up Blogspot blogs
-
-+filter{no-ping} # Removes non-standard ping attributes from anchor and area tags
-
- --------------------------------------------------------------------------
-
- 8.5.15. force-text-mode
-
- Typical use:
-
- Force Privoxy to treat a document as if it was in some kind of
- text format.
-
- Effect:
-
- Declares a document as text, even if the "Content-Type:" isn't
- detected as such.
-
- Type:
-
- Boolean.
-
- Parameter:
-
- N/A
-
- Notes:
-
- As explained above, Privoxy tries to only filter files that are in
- some kind of text format. The same restrictions apply to
- content-type-overwrite. force-text-mode declares a document as
- text, without looking at the "Content-Type:" first.
-
- +---------------------------------------------------------+
- | Warning |
- |---------------------------------------------------------|
- | Think twice before activating this action. Filtering |
- | binary data with regular expressions can cause file |
- | damage. |
- +---------------------------------------------------------+
-
- Example usage:
-
- +force-text-mode
-
-
- --------------------------------------------------------------------------
-
- 8.5.16. forward-override
-
- Typical use:
-
- Change the forwarding settings based on User-Agent or request
- origin
-
- Effect:
-
- Overrules the forward directives in the configuration file.
-
- Type:
-
- Multi-value.
-
- Parameter:
-
- * "forward ." to use a direct connection without any additional
- proxies.
-
- * "forward 127.0.0.1:8123" to use the HTTP proxy listening at
- 127.0.0.1 port 8123.
-
- * "forward-socks4a 127.0.0.1:9050 ." to use the socks4a proxy
- listening at 127.0.0.1 port 9050. Replace "forward-socks4a"
- with "forward-socks4" to use a socks4 connection (with local
- DNS resolution) instead.
-
- * "forward-socks4a 127.0.0.1:9050 proxy.example.org:8000" to
- use the socks4a proxy listening at 127.0.0.1 port 9050 to
- reach the HTTP proxy listening at proxy.example.org port
- 8000. Replace "forward-socks4a" with "forward-socks4" to use
- a socks4 connection (with local DNS resolution) instead.
-
- Notes:
-
- This action takes parameters similar to the forward directives in
- the configuration file, but without the URL pattern. It can be
- used as replacement, but normally it's only used in cases where
- matching based on the request URL isn't sufficient.
-
- +---------------------------------------------------------+
- | Warning |
- |---------------------------------------------------------|
- | Please read the description for the forward directives |
- | before using this action. Forwarding to the wrong |
- | people will reduce your privacy and increase the |
- | chances of man-in-the-middle attacks. |
- | |
- | If the ports are missing or invalid, default values |
- | will be used. This might change in the future and you |
- | shouldn't rely on it. Otherwise incorrect syntax causes |
- | Privoxy to exit. |
- | |
- | Use the show-url-info CGI page to verify that your |
- | forward settings do what you thought the do. |
- +---------------------------------------------------------+
-
- Example usage:
-
- # Always use direct connections for requests previously tagged as
- # "User-Agent: fetch libfetch/2.0" and make sure
- # resuming downloads continues to work.
- # This way you can continue to use Tor for your normal browsing,
- # without overloading the Tor network with your FreeBSD ports updates
- # or downloads of bigger files like ISOs.
- # Note that HTTP headers are easy to fake and therefore their
- # values are as (un)trustworthy as your clients and users.
- {+forward-override{forward .} \
- -hide-if-modified-since \
- -overwrite-last-modified \
- }
- TAG:^User-Agent: fetch libfetch/2\.0$
-
-
- --------------------------------------------------------------------------
-
- 8.5.17. handle-as-empty-document
-
- Typical use:
-
- Mark URLs that should be replaced by empty documents if they get
- blocked
-
- Effect:
-
- This action alone doesn't do anything noticeable. It just marks
- URLs. If the block action also applies, the presence or absence of
- this mark decides whether an HTML "BLOCKED" page, or an empty
- document will be sent to the client as a substitute for the
- blocked content. The empty document isn't literally empty, but
- actually contains a single space.
-
- Type:
-
- Boolean.
-
- Parameter:
-
- N/A
-
- Notes:
-
- Some browsers complain about syntax errors if JavaScript documents
- are blocked with Privoxy's default HTML page; this option can be
- used to silence them. And of course this action can also be used
- to eliminate the Privoxy BLOCKED message in frames.
-
- The content type for the empty document can be specified with
- content-type-overwrite{}, but usually this isn't necessary.
-
- Example usage:
-
- # Block all documents on example.org that end with ".js",
- # but send an empty document instead of the usual HTML message.
- {+block +handle-as-empty-document}
- example.org/.*\.js$
-
-
- --------------------------------------------------------------------------
-
- 8.5.18. handle-as-image
-
- Typical use:
-
- Mark URLs as belonging to images (so they'll be replaced by images
- if they do get blocked, rather than HTML pages)
-
- Effect:
-
- This action alone doesn't do anything noticeable. It just marks
- URLs as images. If the block action also applies, the presence or
- absence of this mark decides whether an HTML "blocked" page, or a
- replacement image (as determined by the set-image-blocker action)
- will be sent to the client as a substitute for the blocked
- content.
-
- Type:
-
- Boolean.
-
- Parameter:
-
- N/A
-
- Notes:
-
- The below generic example section is actually part of
- default.action. It marks all URLs with well-known image file name
- extensions as images and should be left intact.
-
- Users will probably only want to use the handle-as-image action in
- conjunction with block, to block sources of banners, whose URLs
- don't reflect the file type, like in the second example section.
-
- Note that you cannot treat HTML pages as images in most cases. For
- instance, (in-line) ad frames require an HTML page to be sent, or
- they won't display properly. Forcing handle-as-image in this
- situation will not replace the ad frame with an image, but lead to
- error messages.
-
- Example usage (sections):
-
- # Generic image extensions:
- #
- {+handle-as-image}
- /.*\.(gif|jpg|jpeg|png|bmp|ico)$
-
- # These don't look like images, but they're banners and should be
- # blocked as images:
- #
- {+block +handle-as-image}
- some.nasty-banner-server.com/junk.cgi\?output=trash
-
- # Banner source! Who cares if they also have non-image content?
- ad.doubleclick.net
-
- --------------------------------------------------------------------------
-
- 8.5.19. hide-accept-language
-
- Typical use:
-
- Pretend to use different language settings.
-
- Effect:
-
- Deletes or replaces the "Accept-Language:" HTTP header in client
- requests.
-
- Type:
-
- Parameterized.
-
- Parameter:
-
- Keyword: "block", or any user defined value.
-
- Notes:
-
- Faking the browser's language settings can be useful to make a
- foreign User-Agent set with hide-user-agent more believable.
-
- However some sites with content in different languages check the
- "Accept-Language:" to decide which one to take by default.
- Sometimes it isn't possible to later switch to another language
- without changing the "Accept-Language:" header first.
-
- Therefore it's a good idea to either only change the
- "Accept-Language:" header to languages you understand, or to
- languages that aren't wide spread.
-
- Before setting the "Accept-Language:" header to a rare language,
- you should consider that it helps to make your requests unique and
- thus easier to trace. If you don't plan to change this header
- frequently, you should stick to a common language.
-
- Example usage (section):
-
-# Pretend to use Canadian language settings.
-{+hide-accept-language{en-ca} \
-+hide-user-agent{Mozilla/5.0 (X11; U; OpenBSD i386; en-CA; rv:1.8.0.4) Gecko/20060628 Firefox/1.5.0.4} \
-}
-/
-
- --------------------------------------------------------------------------
-
- 8.5.20. hide-content-disposition
-
- Typical use:
-
- Prevent download menus for content you prefer to view inside the
- browser.
-
- Effect:
-
- Deletes or replaces the "Content-Disposition:" HTTP header set by
- some servers.
-
- Type:
-
- Parameterized.
-
- Parameter:
-
- Keyword: "block", or any user defined value.
-
- Notes:
-
- Some servers set the "Content-Disposition:" HTTP header for
- documents they assume you want to save locally before viewing
- them. The "Content-Disposition:" header contains the file name the
- browser is supposed to use by default.
-
- In most browsers that understand this header, it makes it
- impossible to just view the document, without downloading it
- first, even if it's just a simple text file or an image.
-
- Removing the "Content-Disposition:" header helps to prevent this
- annoyance, but some browsers additionally check the
- "Content-Type:" header, before they decide if they can display a
- document without saving it first. In these cases, you have to
- change this header as well, before the browser stops displaying
- download menus.
-
- It is also possible to change the server's file name suggestion to
- another one, but in most cases it isn't worth the time to set it
- up.
-
- This action will probably be removed in the future, use
- server-header filters instead.
-
- Example usage:
-
- # Disarm the download link in Sourceforge's patch tracker
- { -filter \
- +content-type-overwrite{text/plain}\
- +hide-content-disposition{block} }
- .sourceforge.net/tracker/download\.php
-
- --------------------------------------------------------------------------
-
- 8.5.21. hide-if-modified-since
-
- Typical use:
-
- Prevent yet another way to track the user's steps between
- sessions.
-
- Effect:
-
- Deletes the "If-Modified-Since:" HTTP client header or modifies
- its value.
-
- Type:
-
- Parameterized.
-
- Parameter:
-
- Keyword: "block", or a user defined value that specifies a range
- of hours.
-
- Notes:
-
- Removing this header is useful for filter testing, where you want
- to force a real reload instead of getting status code "304", which
- would cause the browser to use a cached copy of the page.
-
- Instead of removing the header, hide-if-modified-since can also
- add or subtract a random amount of time to/from the header's
- value. You specify a range of minutes where the random factor
- should be chosen from and Privoxy does the rest. A negative value
- means subtracting, a positive value adding.
-
- Randomizing the value of the "If-Modified-Since:" makes it less
- likely that the server can use the time as a cookie replacement,
- but you will run into caching problems if the random range is too
- high.
-
- It is a good idea to only use a small negative value and let
- overwrite-last-modified handle the greater changes.
-
- It is also recommended to use this action together with
- crunch-if-none-match, otherwise it's more or less pointless.
-
- Example usage (section):
-
- # Let the browser revalidate but make tracking based on the time less likely.
- {+hide-if-modified-since{-60} \
- +overwrite-last-modified{randomize} \
- +crunch-if-none-match}
- /
-
- --------------------------------------------------------------------------
-
- 8.5.22. hide-forwarded-for-headers
-
- Typical use:
-
- Improve privacy by not forwarding the source of the request in the
- HTTP headers.
-
- Effect:
-
- Deletes any existing "X-Forwarded-for:" HTTP header from client
- requests.
-
- Type:
-
- Boolean.
-
- Parameter:
-
- N/A
-
- Notes:
-
- It is safe and recommended to leave this on.
-
- Example usage:
-
- +hide-forwarded-for-headers
-
- --------------------------------------------------------------------------
-
- 8.5.23. hide-from-header
-
- Typical use:
-
- Keep your (old and ill) browser from telling web servers your
- email address
-
- Effect:
-
- Deletes any existing "From:" HTTP header, or replaces it with the
- specified string.
-
- Type:
-
- Parameterized.
-
- Parameter:
-
- Keyword: "block", or any user defined value.
-
- Notes:
-
- The keyword "block" will completely remove the header (not to be
- confused with the block action).
-
- Alternately, you can specify any value you prefer to be sent to
- the web server. If you do, it is a matter of fairness not to use
- any address that is actually used by a real person.
-
- This action is rarely needed, as modern web browsers don't send
- "From:" headers anymore.
-
- Example usage:
-
- +hide-from-header{block}
-
- or
-
- +hide-from-header{spam-me-senseless@sittingduck.example.com}
-
- --------------------------------------------------------------------------
-
- 8.5.24. hide-referrer
-
- Typical use:
-
- Conceal which link you followed to get to a particular site
-
- Effect:
-
- Deletes the "Referer:" (sic) HTTP header from the client request,
- or replaces it with a forged one.
-
- Type:
-
- Parameterized.
-
- Parameter:
-
- * "conditional-block" to delete the header completely if the
- host has changed.
-
- * "conditional-forge" to forge the header if the host has
- changed.
-
- * "block" to delete the header unconditionally.
-
- * "forge" to pretend to be coming from the homepage of the
- server we are talking to.
-
- * Any other string to set a user defined referrer.
-
- Notes:
-
- conditional-block is the only parameter, that isn't easily
- detected in the server's log file. If it blocks the referrer, the
- request will look like the visitor used a bookmark or typed in the
- address directly.
-
- Leaving the referrer unmodified for requests on the same host
- allows the server owner to see the visitor's "click path", but in
- most cases she could also get that information by comparing other
- parts of the log file: for example the User-Agent if it isn't a
- very common one, or the user's IP address if it doesn't change
- between different requests.
-
- Always blocking the referrer, or using a custom one, can lead to
- failures on servers that check the referrer before they answer any
- requests, in an attempt to prevent their content from being
- embedded or linked to elsewhere.
-
- Both conditional-block and forge will work with referrer checks,
- as long as content and valid referring page are on the same host.
- Most of the time that's the case.
-
- hide-referer is an alternate spelling of hide-referrer and the two
- can be can be freely substituted with each other. ("referrer" is
- the correct English spelling, however the HTTP specification has a
- bug - it requires it to be spelled as "referer".)
-
- Example usage:
-
- +hide-referrer{forge}
-
- or
-
- +hide-referrer{http://www.yahoo.com/}
-
- --------------------------------------------------------------------------
-
- 8.5.25. hide-user-agent
-
- Typical use:
-
- Try to conceal your type of browser and client operating system
-
- Effect:
-
- Replaces the value of the "User-Agent:" HTTP header in client
- requests with the specified value.
-
- Type:
-
- Parameterized.
-
- Parameter:
-
- Any user-defined string.
-
- Notes:
-
- +---------------------------------------------------------+
- | Warning |
- |---------------------------------------------------------|
- | This can lead to problems on web sites that depend on |
- | looking at this header in order to customize their |
- | content for different browsers (which, by the way, is |
- | NOT the right thing to do: good web sites work |
- | browser-independently). |
- +---------------------------------------------------------+
-
- Using this action in multi-user setups or wherever different types
- of browsers will access the same Privoxy is not recommended. In
- single-user, single-browser setups, you might use it to delete
- your OS version information from the headers, because it is an
- invitation to exploit known bugs for your OS. It is also
- occasionally useful to forge this in order to access sites that
- won't let you in otherwise (though there may be a good reason in
- some cases). Example of this: some MSN sites will not let Mozilla
- enter, yet forging to a Netscape 6.1 user-agent works just fine.
- (Must be just a silly MS goof, I'm sure :-).
-
- More information on known user-agent strings can be found at
- http://www.user-agents.org/ and
- http://en.wikipedia.org/wiki/User_agent.
-
- Example usage:
-
- +hide-user-agent{Netscape 6.1 (X11; I; Linux 2.4.18 i686)}
-
- --------------------------------------------------------------------------
-
- 8.5.26. inspect-jpegs
-
- Typical use:
-
- Try to protect against a MS buffer over-run in JPEG processing
-
- Effect:
-
- Protect against a known exploit
-
- Type:
-
- Boolean.
-
- Parameter:
-
- N/A
-
- Notes:
-
- See Microsoft Security Bulletin MS04-028. JPEG images are one of
- the most common image types found across the Internet. The exploit
- as described can allow execution of code on the target system,
- giving an attacker access to the system in question by merely
- planting an altered JPEG image, which would have no obvious
- indications of what lurks inside. This action tries to prevent
- this exploit if delivered through unencrypted HTTP.
-
- Note that the exploit mentioned is several years old and it's
- unlikely that your client is still vulnerable against it. This
- action may be removed in one of the next releases.
-
- Example usage:
-
- +inspect-jpegs
-
- --------------------------------------------------------------------------
-
- 8.5.27. kill-popups
-
- Typical use:
-
- Eliminate those annoying pop-up windows (deprecated)
-
- Effect:
-
- While loading the document, replace JavaScript code that opens
- pop-up windows with (syntactically neutral) dummy code on the fly.
-
- Type:
-
- Boolean.
-
- Parameter:
-
- N/A
-
- Notes:
-
- This action is basically a built-in, hardwired special-purpose
- filter action, but there are important differences: For
- kill-popups, the document need not be buffered, so it can be
- incrementally rendered while downloading. But kill-popups doesn't
- catch as many pop-ups as filter{all-popups} does and is not as
- smart as filter{unsolicited-popups} is.
-
- Think of it as a fast and efficient replacement for a filter that
- you can use if you don't want any filtering at all. Note that it
- doesn't make sense to combine it with any filter action, since as
- soon as one filter applies, the whole document needs to be
- buffered anyway, which destroys the advantage of the kill-popups
- action over its filter equivalent.
-
- Killing all pop-ups unconditionally is problematic. Many shops and
- banks rely on pop-ups to display forms, shopping carts etc, and
- the filter{unsolicited-popups} does a better job of catching only
- the unwanted ones.
-
- If the only kind of pop-ups that you want to kill are exit
- consoles (those really nasty windows that appear when you close an
- other one), you might want to use filter{js-annoyances} instead.
-
- This action is most appropriate for browsers that don't have any
- controls for unwanted pop-ups. Not recommended for general usage.
-
- This action doesn't work very reliable and may be removed in
- future releases.
-
- Example usage:
-
- +kill-popups
-
- --------------------------------------------------------------------------
-
- 8.5.28. limit-connect
-
- Typical use:
-
- Prevent abuse of Privoxy as a TCP proxy relay or disable SSL for
- untrusted sites
-
- Effect:
-
- Specifies to which ports HTTP CONNECT requests are allowable.
-
- Type:
-
- Parameterized.
-
- Parameter:
-
- A comma-separated list of ports or port ranges (the latter using
- dashes, with the minimum defaulting to 0 and the maximum to 65K).
-
- Notes:
-
- By default, i.e. if no limit-connect action applies, Privoxy only
- allows HTTP CONNECT requests to port 443 (the standard, secure
- HTTPS port). Use limit-connect if more fine-grained control is
- desired for some or all destinations.
-
- The CONNECT methods exists in HTTP to allow access to secure
- websites ("https://" URLs) through proxies. It works very simply:
- the proxy connects to the server on the specified port, and then
- short-circuits its connections to the client and to the remote
- server. This means CONNECT-enabled proxies can be used as TCP
- relays very easily.
-
- Privoxy relays HTTPS traffic without seeing the decoded content.
- Websites can leverage this limitation to circumvent Privoxy's
- filters. By specifying an invalid port range you can disable HTTPS
- entirely. If you plan to disable SSL by default, consider enabling
- treat-forbidden-connects-like-blocks as well, to be able to
- quickly create exceptions.
-
- Example usages:
-
-+limit-connect{443} # This is the default and need not be specified.
-+limit-connect{80,443} # Ports 80 and 443 are OK.
-+limit-connect{-3, 7, 20-100, 500-} # Ports less than 3, 7, 20 to 100 and above 500 are OK.
-+limit-connect{-} # All ports are OK
-+limit-connect{,} # No HTTPS/SSL traffic is allowed
-
- --------------------------------------------------------------------------
-
- 8.5.29. prevent-compression
-
- Typical use:
-
- Ensure that servers send the content uncompressed, so it can be
- passed through filters.
-
- Effect:
-
- Removes the Accept-Encoding header which can be used to ask for
- compressed transfer.
-
- Type:
-
- Boolean.
-
- Parameter:
-
- N/A
-
- Notes:
-
- More and more websites send their content compressed by default,
- which is generally a good idea and saves bandwidth. But the
- filter, deanimate-gifs and kill-popups actions need access to the
- uncompressed data.
-
- When compiled with zlib support (available since Privoxy 3.0.7),
- content that should be filtered is decompressed on-the-fly and you
- don't have to worry about this action. If you are using an older
- Privoxy version, or one that hasn't been compiled with zlib
- support, this action can be used to convince the server to send
- the content uncompressed.
-
- Most text-based instances compress very well, the size is seldom
- decreased by less than 50%, for markup-heavy instances like news
- feeds saving more than 90% of the original size isn't unusual.
-
- Not using compression will therefore slow down the transfer, and
- you should only enable this action if you really need it. As of
- Privoxy 3.0.7 it's disabled in all predefined action settings.
-
- Note that some (rare) ill-configured sites don't handle requests
- for uncompressed documents correctly. Broken PHP applications tend
- to send an empty document body, some IIS versions only send the
- beginning of the content. If you enable prevent-compression per
- default, you might want to add exceptions for those sites. See the
- example for how to do that.
-
- Example usage (sections):
-
- # Selectively turn off compression, and enable a filter
- #
- { +filter{tiny-textforms} +prevent-compression }
- # Match only these sites
- .google.
- sourceforge.net
- sf.net
-
- # Or instead, we could set a universal default:
- #
- { +prevent-compression }
- / # Match all sites
-
- # Then maybe make exceptions for broken sites:
- #
- { -prevent-compression }
- .compusa.com/
-
- --------------------------------------------------------------------------
-
- 8.5.30. overwrite-last-modified
-
- Typical use:
-
- Prevent yet another way to track the user's steps between
- sessions.
-
- Effect:
-
- Deletes the "Last-Modified:" HTTP server header or modifies its
- value.
-
- Type:
-
- Parameterized.
-
- Parameter:
-
- One of the keywords: "block", "reset-to-request-time" and
- "randomize"
-
- Notes:
-
- Removing the "Last-Modified:" header is useful for filter testing,
- where you want to force a real reload instead of getting status
- code "304", which would cause the browser to reuse the old version
- of the page.
-
- The "randomize" option overwrites the value of the
- "Last-Modified:" header with a randomly chosen time between the
- original value and the current time. In theory the server could
- send each document with a different "Last-Modified:" header to
- track visits without using cookies. "Randomize" makes it
- impossible and the browser can still revalidate cached documents.
-
- "reset-to-request-time" overwrites the value of the
- "Last-Modified:" header with the current time. You could use this
- option together with hided-if-modified-since to further customize
- your random range.
-
- The preferred parameter here is "randomize". It is safe to use, as
- long as the time settings are more or less correct. If the server
- sets the "Last-Modified:" header to the time of the request, the
- random range becomes zero and the value stays the same. Therefore
- you should later randomize it a second time with
- hided-if-modified-since, just to be sure.
-
- It is also recommended to use this action together with
- crunch-if-none-match.
-
- Example usage:
-
- # Let the browser revalidate without being tracked across sessions
- { +hide-if-modified-since{-60} \
- +overwrite-last-modified{randomize} \
- +crunch-if-none-match}
- /
-
- --------------------------------------------------------------------------
-
- 8.5.31. redirect
-
- Typical use:
-
- Redirect requests to other sites.
-
- Effect:
-
- Convinces the browser that the requested document has been moved
- to another location and the browser should get it from there.
-
- Type:
-
- Parameterized
-
- Parameter:
-
- An absolute URL or a single pcrs command.
-
- Notes:
-
- Requests to which this action applies are answered with a HTTP
- redirect to URLs of your choosing. The new URL is either provided
- as parameter, or derived by applying a single pcrs command to the
- original URL.
-
- This action will be ignored if you use it together with block. It
- can be combined with fast-redirects{check-decoded-url} to redirect
- to a decoded version of a rewritten URL.
-
- Use this action carefully, make sure not to create redirection
- loops and be aware that using your own redirects might make it
- possible to fingerprint your requests.
-
- Example usages:
-
- # Replace example.com's style sheet with another one
- { +redirect{http://localhost/css-replacements/example.com.css} }
- example.com/stylesheet\.css
-
- # Create a short, easy to remember nickname for a favorite site
- # (relies on the browser accept and forward invalid URLs to Privoxy)
- { +redirect{http://www.privoxy.org/user-manual/actions-file.html} }
- a
-
- # Always use the expanded view for Undeadly.org articles
- # (Note the $ at the end of the URL pattern to make sure
- # the request for the rewritten URL isn't redirected as well)
- {+redirect{s@$@&mode=expanded@}}
- undeadly.org/cgi\?action=article&sid=\d*$
-
- --------------------------------------------------------------------------
-
- 8.5.32. send-vanilla-wafer
-
- Typical use:
-
- Feed log analysis scripts with useless data.
-
- Effect:
-
- Sends a cookie with each request stating that you do not accept
- any copyright on cookies sent to you, and asking the site operator
- not to track you.
-
- Type:
-
- Boolean.
-
- Parameter:
-
- N/A
-
- Notes:
-
- The vanilla wafer is a (relatively) unique header and could
- conceivably be used to track you.
-
- This action is rarely used and not enabled in the default
- configuration.
-
- Example usage:
-
- +send-vanilla-wafer
-
- --------------------------------------------------------------------------
-
- 8.5.33. send-wafer
-
- Typical use:
-
- Send custom cookies or feed log analysis scripts with even more
- useless data.
-
- Effect:
-
- Sends a custom, user-defined cookie with each request.
-
- Type:
-
- Multi-value.
-
- Parameter:
-
- A string of the form "name=value".
-
- Notes:
-
- Being multi-valued, multiple instances of this action can apply to
- the same request, resulting in multiple cookies being sent.
-
- This action is rarely used and not enabled in the default
- configuration.
-
- Example usage (section):
-
- {+send-wafer{UsingPrivoxy=true}}
- my-internal-testing-server.void
-
- --------------------------------------------------------------------------
-
- 8.5.34. server-header-filter
-
- Typical use:
-
- Rewrite or remove single server headers.
-
- Effect:
-
- All server headers to which this action applies are filtered
- on-the-fly through the specified regular expression based
- substitutions.
-
- Type:
-
- Parameterized.
-
- Parameter:
-
- The name of a server-header filter, as defined in one of the
- filter files.
-
- Notes:
-
- Server-header filters are applied to each header on its own, not
- to all at once. This makes it easier to diagnose problems, but on
- the downside you can't write filters that only change header x if
- header y's value is z. You can do that by using tags though.
-
- Server-header filters are executed after the other header actions
- have finished and use their output as input.
-
- Please refer to the filter file chapter to learn which
- server-header filters are available by default, and how to create
- your own.
-
- Example usage (section):
-
- {+server-header-filter{html-to-xml}}
- example.org/xml-instance-that-is-delivered-as-html
-
- {+server-header-filter{xml-to-html}}
- example.org/instance-that-is-delivered-as-xml-but-is-not
-
-
- --------------------------------------------------------------------------
-
- 8.5.35. server-header-tagger
-
- Typical use:
-
- Enable or disable filters based on the Content-Type header.
-
- Effect:
-
- Server headers to which this action applies are filtered
- on-the-fly through the specified regular expression based
- substitutions, the result is used as tag.
-
- Type:
-
- Parameterized.
-
- Parameter:
-
- The name of a server-header tagger, as defined in one of the
- filter files.
-
- Notes:
-
- Server-header taggers are applied to each header on its own, and
- as the header isn't modified, each tagger "sees" the original.
-
- Server-header taggers are executed before all other header actions
- that modify server headers. Their tags can be used to control all
- of the other server-header actions, the content filters and the
- crunch actions (redirect and block).
-
- Obviously crunching based on tags created by server-header taggers
- doesn't prevent the request from showing up in the server's log
- file.
-
- Example usage (section):
-
- # Tag every request with the content type declared by the server
- {+server-header-tagger{content-type}}
- /
-
-
- --------------------------------------------------------------------------
-
- 8.5.36. session-cookies-only
-
- Typical use:
-
- Allow only temporary "session" cookies (for the current browser
- session only).
-
- Effect:
-
- Deletes the "expires" field from "Set-Cookie:" server headers.
- Most browsers will not store such cookies permanently and forget
- them in between sessions.
-
- Type:
-
- Boolean.
-
- Parameter:
-
- N/A
-
- Notes:
-
- This is less strict than crunch-incoming-cookies /
- crunch-outgoing-cookies and allows you to browse websites that
- insist or rely on setting cookies, without compromising your
- privacy too badly.
-
- Most browsers will not permanently store cookies that have been
- processed by session-cookies-only and will forget about them
- between sessions. This makes profiling cookies useless, but won't
- break sites which require cookies so that you can log in for
- transactions. This is generally turned on for all sites, and is
- the recommended setting.
-
- It makes no sense at all to use session-cookies-only together with
- crunch-incoming-cookies or crunch-outgoing-cookies. If you do,
- cookies will be plainly killed.
-
- Note that it is up to the browser how it handles such cookies
- without an "expires" field. If you use an exotic browser, you
- might want to try it out to be sure.
-
- This setting also has no effect on cookies that may have been
- stored previously by the browser before starting Privoxy. These
- would have to be removed manually.
-
- Privoxy also uses the content-cookies filter to block some types
- of cookies. Content cookies are not effected by
- session-cookies-only.
-
- Example usage:
-
- +session-cookies-only
-
- --------------------------------------------------------------------------
-
- 8.5.37. set-image-blocker
-
- Typical use:
-
- Choose the replacement for blocked images
-
- Effect:
-
- This action alone doesn't do anything noticeable. If both block
- and handle-as-image also apply, i.e. if the request is to be
- blocked as an image, then the parameter of this action decides
- what will be sent as a replacement.
-
- Type:
-
- Parameterized.
-
- Parameter:
-
- * "pattern" to send a built-in checkerboard pattern image. The
- image is visually decent, scales very well, and makes it
- obvious where banners were busted.
-
- * "blank" to send a built-in transparent image. This makes
- banners disappear completely, but makes it hard to detect
- where Privoxy has blocked images on a given page and
- complicates troubleshooting if Privoxy has blocked innocent
- images, like navigation icons.
-
- * "target-url" to send a redirect to target-url. You can
- redirect to any image anywhere, even in your local filesystem
- via "file:///" URL. (But note that not all browsers support
- redirecting to a local file system).
-
- A good application of redirects is to use special
- Privoxy-built-in URLs, which send the built-in images, as
- target-url. This has the same visual effect as specifying
- "blank" or "pattern" in the first place, but enables your
- browser to cache the replacement image, instead of requesting
- it over and over again.
-
- Notes:
-
- The URLs for the built-in images are
- "http://config.privoxy.org/send-banner?type=type", where type is
- either "blank" or "pattern".
-
- There is a third (advanced) type, called "auto". It is NOT to be
- used in set-image-blocker, but meant for use from filters. Auto
- will select the type of image that would have applied to the
- referring page, had it been an image.
-
- Example usage:
-
- Built-in pattern:
-
- +set-image-blocker{pattern}
-
- Redirect to the BSD daemon:
-
- +set-image-blocker{http://www.freebsd.org/gifs/dae_up3.gif}
-
- Redirect to the built-in pattern for better caching:
-
- +set-image-blocker{http://config.privoxy.org/send-banner?type=pattern}
-
- --------------------------------------------------------------------------
-
- 8.5.38. treat-forbidden-connects-like-blocks
-
- Typical use:
-
- Block forbidden connects with an easy to find error message.
-
- Effect:
-
- If this action is enabled, Privoxy no longer makes a difference
- between forbidden connects and ordinary blocks.
-
- Type:
-
- Boolean
-
- Parameter:
-
- N/A
-
- Notes:
-
- By default Privoxy answers forbidden "Connect" requests with a
- short error message inside the headers. If the browser doesn't
- display headers (most don't), you just see an empty page.
-
- With this action enabled, Privoxy displays the message that is
- used for ordinary blocks instead. If you decide to make an
- exception for the page in question, you can do so by following the
- "See why" link.
-
- For "Connect" requests the clients tell Privoxy which host they
- are interested in, but not which document they plan to get later.
- As a result, the "Go there anyway" wouldn't work and is therefore
- suppressed.
-
- Example usage:
-
- +treat-forbidden-connects-like-blocks
-
- --------------------------------------------------------------------------
-
- 8.5.39. Summary
-
- Note that many of these actions have the potential to cause a page to
- misbehave, possibly even not to display at all. There are many ways a site
- designer may choose to design his site, and what HTTP header content, and
- other criteria, he may depend on. There is no way to have hard and fast
- rules for all sites. See the Appendix for a brief example on
- troubleshooting actions.
-
- --------------------------------------------------------------------------
-
- 8.6. Aliases
-
- Custom "actions", known to Privoxy as "aliases", can be defined by
- combining other actions. These can in turn be invoked just like the
- built-in actions. Currently, an alias name can contain any character
- except space, tab, "=", "{" and "}", but we strongly recommend that you
- only use "a" to "z", "0" to "9", "+", and "-". Alias names are not case
- sensitive, and are not required to start with a "+" or "-" sign, since
- they are merely textually expanded.
-
- Aliases can be used throughout the actions file, but they must be defined
- in a special section at the top of the file! And there can only be one
- such section per actions file. Each actions file may have its own alias
- section, and the aliases defined in it are only visible within that file.
-
- There are two main reasons to use aliases: One is to save typing for
- frequently used combinations of actions, the other one is a gain in
- flexibility: If you decide once how you want to handle shops by defining
- an alias called "shop", you can later change your policy on shops in one
- place, and your changes will take effect everywhere in the actions file
- where the "shop" alias is used. Calling aliases by their purpose also
- makes your actions files more readable.
-
- Currently, there is one big drawback to using aliases, though: Privoxy's
- built-in web-based action file editor honors aliases when reading the
- actions files, but it expands them before writing. So the effects of your
- aliases are of course preserved, but the aliases themselves are lost when
- you edit sections that use aliases with it.
-
- Now let's define some aliases...
-
- # Useful custom aliases we can use later.
- #
- # Note the (required!) section header line and that this section
- # must be at the top of the actions file!
- #
- {{alias}}
-
- # These aliases just save typing later:
- # (Note that some already use other aliases!)
- #
- +crunch-all-cookies = +crunch-incoming-cookies +crunch-outgoing-cookies
- -crunch-all-cookies = -crunch-incoming-cookies -crunch-outgoing-cookies
- +block-as-image = +block +handle-as-image
- allow-all-cookies = -crunch-all-cookies -session-cookies-only -filter{content-cookies}
-
- # These aliases define combinations of actions
- # that are useful for certain types of sites:
- #
- fragile = -block -filter -crunch-all-cookies -fast-redirects -hide-referrer -kill-popups -prevent-compression
-
- shop = -crunch-all-cookies -filter{all-popups} -kill-popups
-
- # Short names for other aliases, for really lazy people ;-)
- #
- c0 = +crunch-all-cookies
- c1 = -crunch-all-cookies
-
- ...and put them to use. These sections would appear in the lower part of
- an actions file and define exceptions to the default actions (as specified
- further up for the "/" pattern):
-
- # These sites are either very complex or very keen on
- # user data and require minimal interference to work:
- #
- {fragile}
- .office.microsoft.com
- .windowsupdate.microsoft.com
- # Gmail is really mail.google.com, not gmail.com
- mail.google.com
-
- # Shopping sites:
- # Allow cookies (for setting and retrieving your customer data)
- #
- {shop}
- .quietpc.com
- .worldpay.com # for quietpc.com
- mybank.example.com
-
- # These shops require pop-ups:
- #
- {-kill-popups -filter{all-popups} -filter{unsolicited-popups}}
- .dabs.com
- .overclockers.co.uk
-
- Aliases like "shop" and "fragile" are typically used for "problem" sites
- that require more than one action to be disabled in order to function
- properly.
-
- --------------------------------------------------------------------------
-
- 8.7. Actions Files Tutorial
-
- The above chapters have shown which actions files there are and how they
- are organized, how actions are specified and applied to URLs, how patterns
- work, and how to define and use aliases. Now, let's look at an example
- default.action and user.action file and see how all these pieces come
- together:
-
- --------------------------------------------------------------------------
-
- 8.7.1. default.action
-
- Every config file should start with a short comment stating its purpose:
-
- # Sample default.action file <ijbswa-developers@lists.sourceforge.net>
-
- Then, since this is the default.action file, the first section is a
- special section for internal use that you needn't change or worry about:
-
- ##########################################################################
- # Settings -- Don't change! For internal Privoxy use ONLY.
- ##########################################################################
-
- {{settings}}
- for-privoxy-version=3.0
-
- After that comes the (optional) alias section. We'll use the example
- section from the above chapter on aliases, that also explains why and how
- aliases are used:
-
-##########################################################################
-# Aliases
-##########################################################################
-{{alias}}
-
- # These aliases just save typing later:
- # (Note that some already use other aliases!)
- #
- +crunch-all-cookies = +crunch-incoming-cookies +crunch-outgoing-cookies
- -crunch-all-cookies = -crunch-incoming-cookies -crunch-outgoing-cookies
- +block-as-image = +block +handle-as-image
- mercy-for-cookies = -crunch-all-cookies -session-cookies-only -filter{content-cookies}
-
- # These aliases define combinations of actions
- # that are useful for certain types of sites:
- #
- fragile = -block -filter -crunch-all-cookies -fast-redirects -hide-referrer -kill-popups
- shop = -crunch-all-cookies -filter{all-popups} -kill-popups
-
- Now come the regular sections, i.e. sets of actions, accompanied by URL
- patterns to which they apply. Remember all actions are disabled when
- matching starts, so we have to explicitly enable the ones we want.
-
- The first regular section is probably the most important. It has only one
- pattern, "/", but this pattern matches all URLs. Therefore, the set of
- actions used in this "default" section will be applied to all requests as
- a start. It can be partly or wholly overridden by later matches further
- down this file, or in user.action, but it will still be largely
- responsible for your overall browsing experience.
-
- Again, at the start of matching, all actions are disabled, so there is no
- need to disable any actions here. (Remember: a "+" preceding the action
- name enables the action, a "-" disables!). Also note how this long line
- has been made more readable by splitting it into multiple lines with line
- continuation.
-
- ##########################################################################
- # "Defaults" section:
- ##########################################################################
- { \
- +deanimate-gifs \
- +filter{html-annoyances} \
- +filter{refresh-tags} \
- +filter{webbugs} \
- +filter{ie-exploits} \
- +hide-forwarded-for-headers \
- +hide-from-header{block} \
- +hide-referrer{forge} \
- +prevent-compression \
- +session-cookies-only \
- +set-image-blocker{pattern} \
- }
- / # forward slash will match *all* potential URL patterns.
-
- The default behavior is now set.
-
- The first of our specialized sections is concerned with "fragile" sites,
- i.e. sites that require minimum interference, because they are either very
- complex or very keen on tracking you (and have mechanisms in place that
- make them unusable for people who avoid being tracked). We will simply use
- our pre-defined fragile alias instead of stating the list of actions
- explicitly:
-
- ##########################################################################
- # Exceptions for sites that'll break under the default action set:
- ##########################################################################
-
- # "Fragile" Use a minimum set of actions for these sites (see alias above):
- #
- { fragile }
- .office.microsoft.com # surprise, surprise!
- .windowsupdate.microsoft.com
- mail.google.com
-
- Shopping sites are not as fragile, but they typically require cookies to
- log in, and pop-up windows for shopping carts or item details. Again,
- we'll use a pre-defined alias:
-
- # Shopping sites:
- #
- { shop }
- .quietpc.com
- .worldpay.com # for quietpc.com
- .jungle.com
- .scan.co.uk
-
- The fast-redirects action, which we enabled per default above, breaks some
- sites. So disable it for popular sites where we know it misbehaves:
-
- { -fast-redirects }
- login.yahoo.com
- edit.*.yahoo.com
- .google.com
- .altavista.com/.*(like|url|link):http
- .altavista.com/trans.*urltext=http
- .nytimes.com
-
- It is important that Privoxy knows which URLs belong to images, so that if
- they are to be blocked, a substitute image can be sent, rather than an
- HTML page. Contacting the remote site to find out is not an option, since
- it would destroy the loading time advantage of banner blocking, and it
- would feed the advertisers (in terms of money and information). We can
- mark any URL as an image with the handle-as-image action, and marking all
- URLs that end in a known image file extension is a good start:
-
- ##########################################################################
- # Images:
- ##########################################################################
-
- # Define which file types will be treated as images, in case they get
- # blocked further down this file:
- #
- { +handle-as-image }
- /.*\.(gif|jpe?g|png|bmp|ico)$
-
- And then there are known banner sources. They often use scripts to
- generate the banners, so it won't be visible from the URL that the request
- is for an image. Hence we block them and mark them as images in one go,
- with the help of our +block-as-image alias defined above. (We could of
- course just as well use +block +handle-as-image here.) Remember that the
- type of the replacement image is chosen by the set-image-blocker action.
- Since all URLs have matched the default section with its
- +set-image-blocker{pattern} action before, it still applies and needn't be
- repeated:
-
- # Known ad generators:
- #
- { +block-as-image }
- ar.atwola.com
- .ad.doubleclick.net
- .ad.*.doubleclick.net
- .a.yimg.com/(?:(?!/i/).)*$
- .a[0-9].yimg.com/(?:(?!/i/).)*$
- bs*.gsanet.com
- .qkimg.net
-
- One of the most important jobs of Privoxy is to block banners. Many of
- these can be "blocked" by the filter{banners-by-size} action, which we
- enabled above, and which deletes the references to banner images from the
- pages while they are loaded, so the browser doesn't request them anymore,
- and hence they don't need to be blocked here. But this naturally doesn't
- catch all banners, and some people choose not to use filters, so we need a
- comprehensive list of patterns for banner URLs here, and apply the block
- action to them.
-
- First comes many generic patterns, which do most of the work, by matching
- typical domain and path name components of banners. Then comes a list of
- individual patterns for specific sites, which is omitted here to keep the
- example short:
-
- ##########################################################################
- # Block these fine banners:
- ##########################################################################
- { +block }
-
- # Generic patterns:
- #
- ad*.
- .*ads.
- banner?.
- count*.
- /.*count(er)?\.(pl|cgi|exe|dll|asp|php[34]?)
- /(?:.*/)?(publicite|werbung|rekla(ma|me|am)|annonse|maino(kset|nta|s)?)/
-
- # Site-specific patterns (abbreviated):
- #
- .hitbox.com
-
- It's quite remarkable how many advertisers actually call their banner
- servers ads.company.com, or call the directory in which the banners are
- stored simply "banners". So the above generic patterns are surprisingly
- effective.
-
- But being very generic, they necessarily also catch URLs that we don't
- want to block. The pattern .*ads. e.g. catches "nasty-ads.nasty-corp.com"
- as intended, but also "downloads.sourcefroge.net" or
- "adsl.some-provider.net." So here come some well-known exceptions to the
- +block section above.
-
- Note that these are exceptions to exceptions from the default! Consider
- the URL "downloads.sourcefroge.net": Initially, all actions are
- deactivated, so it wouldn't get blocked. Then comes the defaults section,
- which matches the URL, but just deactivates the block action once again.
- Then it matches .*ads., an exception to the general non-blocking policy,
- and suddenly +block applies. And now, it'll match .*loads., where -block
- applies, so (unless it matches again further down) it ends up with no
- block action applying.
-
- ##########################################################################
- # Save some innocent victims of the above generic block patterns:
- ##########################################################################
-
- # By domain:
- #
- { -block }
- adv[io]*. # (for advogato.org and advice.*)
- adsl. # (has nothing to do with ads)
- adobe. # (has nothing to do with ads either)
- ad[ud]*. # (adult.* and add.*)
- .edu # (universities don't host banners (yet!))
- .*loads. # (downloads, uploads etc)
-
- # By path:
- #
- /.*loads/
-
- # Site-specific:
- #
- www.globalintersec.com/adv # (adv = advanced)
- www.ugu.com/sui/ugu/adv
-
- Filtering source code can have nasty side effects, so make an exception
- for our friends at sourceforge.net, and all paths with "cvs" in them. Note
- that -filter disables all filters in one fell swoop!
-
- # Don't filter code!
- #
- { -filter }
- /(.*/)?cvs
- bugzilla.
- developer.
- wiki.
- .sourceforge.net
-
- The actual default.action is of course much more comprehensive, but we
- hope this example made clear how it works.
-
- --------------------------------------------------------------------------
-
- 8.7.2. user.action
-
- So far we are painting with a broad brush by setting general policies,
- which would be a reasonable starting point for many people. Now, you might
- want to be more specific and have customized rules that are more suitable
- to your personal habits and preferences. These would be for narrowly
- defined situations like your ISP or your bank, and should be placed in
- user.action, which is parsed after all other actions files and hence has
- the last word, over-riding any previously defined actions. user.action is
- also a safe place for your personal settings, since default.action is
- actively maintained by the Privoxy developers and you'll probably want to
- install updated versions from time to time.
-
- So let's look at a few examples of things that one might typically do in
- user.action:
-
- # My user.action file. <fred@example.com>
-
- As aliases are local to the actions file that they are defined in, you
- can't use the ones from default.action, unless you repeat them here:
-
-# Aliases are local to the file they are defined in.
-# (Re-)define aliases for this file:
-#
-{{alias}}
-#
-# These aliases just save typing later, and the alias names should
-# be self explanatory.
-#
-+crunch-all-cookies = +crunch-incoming-cookies +crunch-outgoing-cookies
--crunch-all-cookies = -crunch-incoming-cookies -crunch-outgoing-cookies
- allow-all-cookies = -crunch-all-cookies -session-cookies-only
- allow-popups = -filter{all-popups} -kill-popups
-+block-as-image = +block +handle-as-image
--block-as-image = -block
-
-# These aliases define combinations of actions that are useful for
-# certain types of sites:
-#
-fragile = -block -crunch-all-cookies -filter -fast-redirects -hide-referrer -kill-popups
-shop = -crunch-all-cookies allow-popups
-
-# Allow ads for selected useful free sites:
-#
-allow-ads = -block -filter{banners-by-size} -filter{banners-by-link}
-
-# Alias for specific file types that are text, but might have conflicting
-# MIME types. We want the browser to force these to be text documents.
-handle-as-text = -filter +-content-type-overwrite{text/plain} +-force-text-mode -hide-content-disposition
-
-
-
- Say you have accounts on some sites that you visit regularly, and you
- don't want to have to log in manually each time. So you'd like to allow
- persistent cookies for these sites. The allow-all-cookies alias defined
- above does exactly that, i.e. it disables crunching of cookies in any
- direction, and the processing of cookies to make them only temporary.
-
- { allow-all-cookies }
- sourceforge.net
- .yahoo.com
- .msdn.microsoft.com
- .redhat.com
-
- Your bank is allergic to some filter, but you don't know which, so you
- disable them all:
-
- { -filter }
- .your-home-banking-site.com
-
- Some file types you may not want to filter for various reasons:
-
- # Technical documentation is likely to contain strings that might
- # erroneously get altered by the JavaScript-oriented filters:
- #
- .tldp.org
- /(.*/)?selfhtml/
-
- # And this stupid host sends streaming video with a wrong MIME type,
- # so that Privoxy thinks it is getting HTML and starts filtering:
- #
- stupid-server.example.com/
-
- Example of a simple block action. Say you've seen an ad on your favourite
- page on example.com that you want to get rid of. You have right-clicked
- the image, selected "copy image location" and pasted the URL below while
- removing the leading http://, into a { +block } section. Note that {
- +handle-as-image } need not be specified, since all URLs ending in .gif
- will be tagged as images by the general rules as set in default.action
- anyway:
-
- { +block }
- www.example.com/nasty-ads/sponsor\.gif
- another.example.net/more/junk/here/
-
- The URLs of dynamically generated banners, especially from large banner
- farms, often don't use the well-known image file name extensions, which
- makes it impossible for Privoxy to guess the file type just by looking at
- the URL. You can use the +block-as-image alias defined above for these
- cases. Note that objects which match this rule but then turn out NOT to be
- an image are typically rendered as a "broken image" icon by the browser.
- Use cautiously.
-
- { +block-as-image }
- .doubleclick.net
- .fastclick.net
- /Realmedia/ads/
- ar.atwola.com/
-
- Now you noticed that the default configuration breaks Forbes Magazine, but
- you were too lazy to find out which action is the culprit, and you were
- again too lazy to give feedback, so you just used the fragile alias on the
- site, and -- whoa! -- it worked. The fragile aliases disables those
- actions that are most likely to break a site. Also, good for testing
- purposes to see if it is Privoxy that is causing the problem or not. We
- later find other regular sites that misbehave, and add those to our
- personalized list of troublemakers:
-
- { fragile }
- .forbes.com
- webmail.example.com
- .mybank.com
-
- You like the "fun" text replacements in default.filter, but it is disabled
- in the distributed actions file. So you'd like to turn it on in your
- private, update-safe config, once and for all:
-
- { +filter{fun} }
- / # For ALL sites!
-
- Note that the above is not really a good idea: There are exceptions to the
- filters in default.action for things that really shouldn't be filtered,
- like code on CVS->Web interfaces. Since user.action has the last word,
- these exceptions won't be valid for the "fun" filtering specified here.
-
- You might also worry about how your favourite free websites are funded,
- and find that they rely on displaying banner advertisements to survive. So
- you might want to specifically allow banners for those sites that you feel
- provide value to you:
-
- { allow-ads }
- .sourceforge.net
- .slashdot.org
- .osdn.net
-
- Note that allow-ads has been aliased to -block, -filter{banners-by-size},
- and -filter{banners-by-link} above.
-
- Invoke another alias here to force an over-ride of the MIME type
- application/x-sh which typically would open a download type dialog. In my
- case, I want to look at the shell script, and then I can save it should I
- choose to.
-
- { handle-as-text }
- /.*\.sh$
-
- user.action is generally the best place to define exceptions and additions
- to the default policies of default.action. Some actions are safe to have
- their default policies set here though. So let's set a default policy to
- have a "blank" image as opposed to the checkerboard pattern for ALL sites.
- "/" of course matches all URL paths and patterns:
-
- { +set-image-blocker{blank} }
- / # ALL sites
-
- --------------------------------------------------------------------------
-
-9. Filter Files
-
- On-the-fly text substitutions need to be defined in a "filter file". Once
- defined, they can then be invoked as an "action".
-
- Privoxy supports three different filter actions: filter to rewrite the
- content that is send to the client, client-header-filter to rewrite
- headers that are send by the client, and server-header-filter to rewrite
- headers that are send by the server.
-
- Privoxy also supports two tagger actions: client-header-tagger and
- server-header-tagger. Taggers and filters use the same syntax in the
- filter files, the difference is that taggers don't modify the text they
- are filtering, but use a rewritten version of the filtered text as tag.
- The tags can then be used to change the applying actions through sections
- with tag-patterns.
-
- Multiple filter files can be defined through the filterfile config
- directive. The filters as supplied by the developers are located in
- default.filter. It is recommended that any locally defined or modified
- filters go in a separately defined file such as user.filter.
-
- Common tasks for content filters are to eliminate common annoyances in
- HTML and JavaScript, such as pop-up windows, exit consoles, crippled
- windows without navigation tools, the infamous <BLINK> tag etc, to
- suppress images with certain width and height attributes (standard banner
- sizes or web-bugs), or just to have fun.
-
- Enabled content filters are applied to any content whose "Content Type"
- header is recognised as a sign of text-based content, with the exception
- of text/plain. Use the force-text-mode action to also filter other
- content.
-
- Substitutions are made at the source level, so if you want to "roll your
- own" filters, you should first be familiar with HTML syntax, and, of
- course, regular expressions.
-
- Just like the actions files, the filter file is organized in sections,
- which are called filters here. Each filter consists of a heading line,
- that starts with one of the keywords FILTER:, CLIENT-HEADER-FILTER: or
- SERVER-HEADER-FILTER: followed by the filter's name, and a short (one
- line) description of what it does. Below that line come the jobs, i.e.
- lines that define the actual text substitutions. By convention, the name
- of a filter should describe what the filter eliminates. The comment is
- used in the web-based user interface.
-
- Once a filter called name has been defined in the filter file, it can be
- invoked by using an action of the form +filter{name} in any actions file.
-
- Filter definitions start with a header line that contains the filter type,
- the filter name and the filter description. A content filter header line
- for a filter called "foo" could look like this:
-
- FILTER: foo Replace all "foo" with "bar"
-
- Below that line, and up to the next header line, come the jobs that define
- what text replacements the filter executes. They are specified in a syntax
- that imitates Perl's s/// operator. If you are familiar with Perl, you
- will find this to be quite intuitive, and may want to look at the PCRS
- documentation for the subtle differences to Perl behaviour. Most notably,
- the non-standard option letter U is supported, which turns the default to
- ungreedy matching.
-
- If you are new to "Regular Expressions", you might want to take a look at
- the Appendix on regular expressions, and see the Perl manual for the s///
- operator's syntax and Perl-style regular expressions in general. The below
- examples might also help to get you started.
-
- --------------------------------------------------------------------------
-
- 9.1. Filter File Tutorial
-
- Now, let's complete our "foo" content filter. We have already defined the
- heading, but the jobs are still missing. Since all it does is to replace
- "foo" with "bar", there is only one (trivial) job needed:
-
- s/foo/bar/
-
- But wait! Didn't the comment say that all occurrences of "foo" should be
- replaced? Our current job will only take care of the first "foo" on each
- page. For global substitution, we'll need to add the g option:
-
- s/foo/bar/g
-
- Our complete filter now looks like this:
-
- FILTER: foo Replace all "foo" with "bar"
- s/foo/bar/g
-
- Let's look at some real filters for more interesting examples. Here you
- see a filter that protects against some common annoyances that arise from
- JavaScript abuse. Let's look at its jobs one after the other:
-
-FILTER: js-annoyances Get rid of particularly annoying JavaScript abuse
-
-# Get rid of JavaScript referrer tracking. Test page: http://www.randomoddness.com/untitled.htm
-#
-s|(<script.*)document\.referrer(.*</script>)|$1"Not Your Business!"$2|Usg
-
- Following the header line and a comment, you see the job. Note that it
- uses | as the delimiter instead of /, because the pattern contains a
- forward slash, which would otherwise have to be escaped by a backslash
- (\).
-
- Now, let's examine the pattern: it starts with the text <script.* enclosed
- in parentheses. Since the dot matches any character, and * means: "Match
- an arbitrary number of the element left of myself", this matches
- "<script", followed by any text, i.e. it matches the whole page, from the
- start of the first <script> tag.
-
- That's more than we want, but the pattern continues: document\.referrer
- matches only the exact string "document.referrer". The dot needed to be
- escaped, i.e. preceded by a backslash, to take away its special meaning as
- a joker, and make it just a regular dot. So far, the meaning is: Match
- from the start of the first <script> tag in a the page, up to, and
- including, the text "document.referrer", if both are present in the page
- (and appear in that order).
-
- But there's still more pattern to go. The next element, again enclosed in
- parentheses, is .*</script>. You already know what .* means, so the whole
- pattern translates to: Match from the start of the first <script> tag in a
- page to the end of the last <script> tag, provided that the text
- "document.referrer" appears somewhere in between.
-
- This is still not the whole story, since we have ignored the options and
- the parentheses: The portions of the page matched by sub-patterns that are
- enclosed in parentheses, will be remembered and be available through the
- variables $1, $2, ... in the substitute. The U option switches to ungreedy
- matching, which means that the first .* in the pattern will only "eat up"
- all text in between "<script" and the first occurrence of
- "document.referrer", and that the second .* will only span the text up to
- the first "</script>" tag. Furthermore, the s option says that the match
- may span multiple lines in the page, and the g option again means that the
- substitution is global.
-
- So, to summarize, the pattern means: Match all scripts that contain the
- text "document.referrer". Remember the parts of the script from (and
- including) the start tag up to (and excluding) the string
- "document.referrer" as $1, and the part following that string, up to and
- including the closing tag, as $2.
-
- Now the pattern is deciphered, but wasn't this about substituting things?
- So lets look at the substitute: $1"Not Your Business!"$2 is easy to read:
- The text remembered as $1, followed by "Not Your Business!" (including the
- quotation marks!), followed by the text remembered as $2. This produces an
- exact copy of the original string, with the middle part (the
- "document.referrer") replaced by "Not Your Business!".
-
- The whole job now reads: Replace "document.referrer" by "Not Your
- Business!" wherever it appears inside a <script> tag. Note that this job
- won't break JavaScript syntax, since both the original and the replacement
- are syntactically valid string objects. The script just won't have access
- to the referrer information anymore.
-
- We'll show you two other jobs from the JavaScript taming department, but
- this time only point out the constructs of special interest:
-
- # The status bar is for displaying link targets, not pointless blahblah
- #
- s/window\.status\s*=\s*(['"]).*?\1/dUmMy=1/ig
-
- \s stands for whitespace characters (space, tab, newline, carriage return,
- form feed), so that \s* means: "zero or more whitespace". The ? in .*?
- makes this matching of arbitrary text ungreedy. (Note that the U option is
- not set). The ['"] construct means: "a single or a double quote". Finally,
- \1 is a back-reference to the first parenthesis just like $1 above, with
- the difference that in the pattern, a backslash indicates a
- back-reference, whereas in the substitute, it's the dollar.
-
- So what does this job do? It replaces assignments of single- or
- double-quoted strings to the "window.status" object with a dummy
- assignment (using a variable name that is hopefully odd enough not to
- conflict with real variables in scripts). Thus, it catches many cases
- where e.g. pointless descriptions are displayed in the status bar instead
- of the link target when you move your mouse over links.
-
-# Kill OnUnload popups. Yummy. Test: http://www.zdnet.com/zdsubs/yahoo/tree/yfs.html
-#
-s/(<body [^>]*)onunload(.*>)/$1never$2/iU
-
- Including the OnUnload event binding in the HTML DOM was a CRIME. When I
- close a browser window, I want it to close and die. Basta. This job
- replaces the "onunload" attribute in "<body>" tags with the dummy word
- never. Note that the i option makes the pattern matching case-insensitive.
- Also note that ungreedy matching alone doesn't always guarantee a minimal
- match: In the first parenthesis, we had to use [^>]* instead of .* to
- prevent the match from exceeding the <body> tag if it doesn't contain
- "OnUnload", but the page's content does.
-
- The last example is from the fun department:
-
- FILTER: fun Fun text replacements
-
- # Spice the daily news:
- #
- s/microsoft(?!\.com)/MicroSuck/ig
-
- Note the (?!\.com) part (a so-called negative lookahead) in the job's
- pattern, which means: Don't match, if the string ".com" appears directly
- following "microsoft" in the page. This prevents links to microsoft.com
- from being trashed, while still replacing the word everywhere else.
-
- # Buzzword Bingo (example for extended regex syntax)
- #
- s* industry[ -]leading \
- | cutting[ -]edge \
- | customer[ -]focused \
- | market[ -]driven \
- | award[ -]winning # Comments are OK, too! \
- | high[ -]performance \
- | solutions[ -]based \
- | unmatched \
- | unparalleled \
- | unrivalled \
- *<font color="red"><b>BINGO!</b></font> \
- *igx
-
- The x option in this job turns on extended syntax, and allows for e.g. the
- liberal use of (non-interpreted!) whitespace for nicer formatting.
-
- You get the idea?
-
- --------------------------------------------------------------------------
-
- 9.2. The Pre-defined Filters
-
- The distribution default.filter file contains a selection of pre-defined
- filters for your convenience:
-
- js-annoyances
-
- The purpose of this filter is to get rid of particularly annoying
- JavaScript abuse. To that end, it
-
- * replaces JavaScript references to the browser's referrer
- information with the string "Not Your Business!". This
- compliments the hide-referrer action on the content level.
-
- * removes the bindings to the DOM's unload event which we feel
- has no right to exist and is responsible for most "exit
- consoles", i.e. nasty windows that pop up when you close
- another one.
-
- * removes code that causes new windows to be opened with
- undesired properties, such as being full-screen,
- non-resizeable, without location, status or menu bar etc.
-
- Use with caution. This is an aggressive filter, and can break
- sites that rely heavily on JavaScript.
-
- js-events
-
- This is a very radical measure. It removes virtually all
- JavaScript event bindings, which means that scripts can not react
- to user actions such as mouse movements or clicks, window resizing
- etc, anymore. Use with caution!
-
- We strongly discourage using this filter as a default since it
- breaks many legitimate scripts. It is meant for use only on
- extra-nasty sites (should you really need to go there).
-
- html-annoyances
-
- This filter will undo many common instances of HTML based abuse.
-
- The BLINK and MARQUEE tags are neutralized (yeah baby!), and
- browser windows will be created as resizeable (as of course they
- should be!), and will have location, scroll and menu bars -- even
- if specified otherwise.
-
- content-cookies
-
- Most cookies are set in the HTTP dialog, where they can be
- intercepted by the crunch-incoming-cookies and
- crunch-outgoing-cookies actions. But web sites increasingly make
- use of HTML meta tags and JavaScript to sneak cookies to the
- browser on the content level.
-
- This filter disables most HTML and JavaScript code that reads or
- sets cookies. It cannot detect all clever uses of these types of
- code, so it should not be relied on as an absolute fix. Use it
- wherever you would also use the cookie crunch actions.
-
- refresh tags
-
- Disable any refresh tags if the interval is greater than nine
- seconds (so that redirections done via refresh tags are not
- destroyed). This is useful for dial-on-demand setups, or for those
- who find this HTML feature annoying.
-
- unsolicited-popups
-
- This filter attempts to prevent only "unsolicited" pop-up windows
- from opening, yet still allow pop-up windows that the user has
- explicitly chosen to open. It was added in version 3.0.1, as an
- improvement over earlier such filters.
-
- Technical note: The filter works by redefining the window.open
- JavaScript function to a dummy function, PrivoxyWindowOpen(),
- during the loading and rendering phase of each HTML page access,
- and restoring the function afterward.
-
- This is recommended only for browsers that cannot perform this
- function reliably themselves. And be aware that some sites require
- such windows in order to function normally. Use with caution.
-
- all-popups
-
- Attempt to prevent all pop-up windows from opening. Note this
- should be used with even more discretion than the above, since it
- is more likely to break some sites that require pop-ups for normal
- usage. Use with caution.
-
- img-reorder
-
- This is a helper filter that has no value if used alone. It makes
- the banners-by-size and banners-by-link (see below) filters more
- effective and should be enabled together with them.
-
- banners-by-size
-
- This filter removes image tags purely based on what size they are.
- Fortunately for us, many ads and banner images tend to conform to
- certain standardized sizes, which makes this filter quite
- effective for ad stripping purposes.
-
- Occasionally this filter will cause false positives on images that
- are not ads, but just happen to be of one of the standard banner
- sizes.
-
- Recommended only for those who require extreme ad blocking. The
- default block rules should catch 95+% of all ads without this
- filter enabled.
-
- banners-by-link
-
- This is an experimental filter that attempts to kill any banners
- if their URLs seem to point to known or suspected click trackers.
- It is currently not of much value and is not recommended for use
- by default.
-
- webbugs
-
- Webbugs are small, invisible images (technically 1X1 GIF images),
- that are used to track users across websites, and collect
- information on them. As an HTML page is loaded by the browser, an
- embedded image tag causes the browser to contact a third-party
- site, disclosing the tracking information through the requested
- URL and/or cookies for that third-party domain, without the user
- ever becoming aware of the interaction with the third-party site.
- HTML-ized spam also uses a similar technique to verify email
- addresses.
-
- This filter removes the HTML code that loads such "webbugs".
-
- tiny-textforms
-
- A rather special-purpose filter that can be used to enlarge
- textareas (those multi-line text boxes in web forms) and turn off
- hard word wrap in them. It was written for the sourceforge.net
- tracker system where such boxes are a nuisance, but it can be
- handy on other sites, too.
-
- It is not recommended to use this filter as a default.
-
- jumping-windows
-
- Many consider windows that move, or resize themselves to be
- abusive. This filter neutralizes the related JavaScript code. Note
- that some sites might not display or behave as intended when using
- this filter. Use with caution.
-
- frameset-borders
-
- Some web designers seem to assume that everyone in the world will
- view their web sites using the same browser brand and version,
- screen resolution etc, because only that assumption could explain
- why they'd use static frame sizes, yet prevent their frames from
- being resized by the user, should they be too small to show their
- whole content.
-
- This filter removes the related HTML code. It should only be
- applied to sites which need it.
-
- demoronizer
-
- Many Microsoft products that generate HTML use non-standard
- extensions (read: violations) of the ISO 8859-1 aka Latin-1
- character set. This can cause those HTML documents to display with
- errors on standard-compliant platforms.
-
- This filter translates the MS-only characters into Latin-1
- equivalents. It is not necessary when using MS products, and will
- cause corruption of all documents that use 8-bit character sets
- other than Latin-1. It's mostly worthwhile for Europeans on non-MS
- platforms, if weird garbage characters sometimes appear on some
- pages, or user agents that don't correct for this on the fly.
-
- shockwave-flash
-
- A filter for shockwave haters. As the name suggests, this filter
- strips code out of web pages that is used to embed shockwave flash
- objects.
-
- quicktime-kioskmode
-
- Change HTML code that embeds Quicktime objects so that kioskmode,
- which prevents saving, is disabled.
-
- fun
-
- Text replacements for subversive browsing fun. Make fun of your
- favorite Monopolist or play buzzword bingo.
-
- crude-parental
-
- A demonstration-only filter that shows how Privoxy can be used to
- delete web content on a keyword basis.
-
- ie-exploits
-
- An experimental collection of text replacements to disable
- malicious HTML and JavaScript code that exploits known security
- holes in Internet Explorer.
-
- Presently, it only protects against Nimda and a cross-site
- scripting bug, and would need active maintenance to provide more
- substantial protection.
-
- site-specifics
-
- Some web sites have very specific problems, the cure for which
- doesn't apply anywhere else, or could even cause damage on other
- sites.
-
- This is a collection of such site-specific cures which should only
- be applied to the sites they were intended for, which is what the
- supplied default.action file does. Users shouldn't need to change
- anything regarding this filter.
-
- google
-
- A CSS based block for Google text ads. Also removes a width
- limitation and the toolbar advertisement.
-
- yahoo
-
- Another CSS based block, this time for Yahoo text ads. And removes
- a width limitation as well.
-
- msn
-
- Another CSS based block, this time for MSN text ads. And removes
- tracking URLs, as well as a width limitation.
-
- blogspot
-
- Cleans up some Blogspot blogs. Read the fine print before using
- this one!
-
- This filter also intentionally removes some navigation stuff and
- sets the page width to 100%. As a result, some rounded "corners"
- would appear to early or not at all and as fixing this would
- require a browser that understands background-size (CSS3), they
- are removed instead.
-
- xml-to-html
-
- Server-header filter to change the Content-Type from xml to html.
-
- html-to-xml
-
- Server-header filter to change the Content-Type from html to xml.
-
- no-ping
-
- Removes the non-standard ping attribute from anchor and area HTML
- tags.
-
- hide-tor-exit-notation
-
- Client-header filter to remove the Tor exit node notation found in
- Host and Referer headers.
-
- If Privoxy and Tor are chained and Privoxy is configured to use
- socks4a, one can use "http://www.example.org.foobar.exit/" to
- access the host "www.example.org" through the Tor exit node
- "foobar".
-
- As the HTTP client isn't aware of this notation, it treats the
- whole string "www.example.org.foobar.exit" as host and uses it for
- the "Host" and "Referer" headers. From the server's point of view
- the resulting headers are invalid and can cause problems.
-
- An invalid "Referer" header can trigger "hot-linking" protections,
- an invalid "Host" header will make it impossible for the server to
- find the right vhost (several domains hosted on the same IP
- address).
-
- This client-header filter removes the "foo.exit" part in those
- headers to prevent the mentioned problems. Note that it only
- modifies the HTTP headers, it doesn't make it impossible for the
- server to detect your Tor exit node based on the IP address the
- request is coming from.
-
- --------------------------------------------------------------------------
-
-10. Privoxy's Template Files
-
- All Privoxy built-in pages, i.e. error pages such as the "404 - No Such
- Domain" error page, the "BLOCKED" page and all pages of its web-based user
- interface, are generated from templates. (Privoxy must be running for the
- above links to work as intended.)
-
- These templates are stored in a subdirectory of the configuration
- directory called templates. On Unixish platforms, this is typically
- /etc/privoxy/templates/.
-
- The templates are basically normal HTML files, but with place-holders
- (called symbols or exports), which Privoxy fills at run time. It is
- possible to edit the templates with a normal text editor, should you want
- to customize them. (Not recommended for the casual user). Should you
- create your own custom templates, you should use the config setting
- templdir to specify an alternate location, so your templates do not get
- overwritten during upgrades.
-
- Note that just like in configuration files, lines starting with # are
- ignored when the templates are filled in.
-
- The place-holders are of the form @name@, and you will find a list of
- available symbols, which vary from template to template, in the comments
- at the start of each file. Note that these comments are not always
- accurate, and that it's probably best to look at the existing HTML code to
- find out which symbols are supported and what they are filled in with.
-
- A special application of this substitution mechanism is to make whole
- blocks of HTML code disappear when a specific symbol is set. We use this
- for many purposes, one of them being to include the beta warning in all
- our user interface (CGI) pages when Privoxy is in an alpha or beta
- development stage:
-
- <!-- @if-unstable-start -->
-
- ... beta warning HTML code goes here ...
-
- <!-- if-unstable-end@ -->
-
- If the "unstable" symbol is set, everything in between and including
- @if-unstable-start and if-unstable-end@ will disappear, leaving nothing
- but an empty comment:
-
- <!-- -->
-
- There's also an if-then-else construct and an #include mechanism, but
- you'll sure find out if you are inclined to edit the templates ;-)
-
- All templates refer to a style located at
- http://config.privoxy.org/send-stylesheet. This is, of course, locally
- served by Privoxy and the source for it can be found and edited in the
- cgi-style.css template.
-
- --------------------------------------------------------------------------
-
-11. Contacting the Developers, Bug Reporting and Feature Requests
-
- We value your feedback. In fact, we rely on it to improve Privoxy and its
- configuration. However, please note the following hints, so we can provide
- you with the best support:
-
- --------------------------------------------------------------------------
-
- 11.1. Get Support
-
- For casual users, our support forum at SourceForge is probably best
- suited: http://sourceforge.net/tracker/?group_id=11118&atid=211118
-
- All users are of course welcome to discuss their issues on the users
- mailing list, where the developers also hang around.
-
- Note that the Privoxy mailing lists are moderated. Posts from unsubscribed
- addresses have to be accepted manually by a moderator. This may cause a
- delay of several days and if you use a subject that doesn't clearly
- mention Privoxy or one of its features, your message may be accidentally
- discarded as spam.
-
- If you aren't subscribed, you should therefore spend a few seconds to come
- up with a proper subject. Additionally you should make it clear that you
- want to get CC'd. Otherwise some responses will be directed to the mailing
- list only, and you won't see them.
-
- --------------------------------------------------------------------------
-
- 11.2. Reporting Problems
-
- "Problems" for our purposes, come in two forms:
-
- * Configuration issues, such as ads that slip through, or sites that
- don't function properly due to one Privoxy "action" or another being
- turned "on".
-
- * "Bugs" in the programming code that makes up Privoxy, such as that
- might cause a crash.
-
- --------------------------------------------------------------------------
-
- 11.2.1. Reporting Ads or Other Configuration Problems
-
- Please send feedback on ads that slipped through, innocent images that
- were blocked, sites that don't work properly, and other configuration
- related problem of default.action file, to
- http://sourceforge.net/tracker/?group_id=11118&atid=460288, the Actions
- File Tracker.
-
- New, improved default.action files may occasionally be made available
- based on your feedback. These will be announced on the ijbswa-announce
- list and available from our the files section of our project page.
-
- --------------------------------------------------------------------------
-
- 11.2.2. Reporting Bugs
-
- Please report all bugs through our bug tracker:
- http://sourceforge.net/tracker/?group_id=11118&atid=111118.
-
- Before doing so, please make sure that the bug has not already been
- submitted and observe the additional hints at the top of the submit form.
- If already submitted, please feel free to add any info to the original
- report that might help to solve the issue.
-
- Please try to verify that it is a Privoxy bug, and not a browser or site
- bug or documented behaviour that just happens to be different than what
- you expected. If unsure, try toggling off Privoxy, and see if the problem
- persists.
-
- If you are using your own custom configuration, please try the stock
- configs to see if the problem is configuration related. If you're having
- problems with a feature that is disabled by default, please ask around on
- the mailing list if others can reproduce the problem.
-
- If you aren't using the latest Privoxy version, the bug may have been
- found and fixed in the meantime. We would appreciate if you could take the
- time to upgrade to the latest version (or even the latest CVS snapshot)
- and verify that your bug still exists.
-
- Please be sure to provide the following information:
-
- * The exact Privoxy version you are using (if you got the source from
- CVS, please also provide the source code revisions as shown in
- http://config.privoxy.org/show-version).
-
- * The operating system and versions you run Privoxy on, (e.g. Windows XP
- SP2), if you are using a Unix flavor, sending the output of "uname -a"
- should do, in case of GNU/Linux, please also name the distribution.
-
- * The name, platform, and version of the browser you were using (e.g.
- Internet Explorer v5.5 for Mac).
-
- * The URL where the problem occurred, or some way for us to duplicate
- the problem (e.g. http://somesite.example.com/?somethingelse=123).
-
- * Whether your version of Privoxy is one supplied by the Privoxy
- developers via SourceForge, or if you got your copy somewhere else.
-
- * Whether you are using Privoxy in tandem with another proxy such as
- Tor. If so, please temporary disable the other proxy to see if the
- symptoms change.
-
- * Whether you are using a personal firewall product. If so, does Privoxy
- work without it?
-
- * Any other pertinent information to help identify the problem such as
- config or log file excerpts (yes, you should have log file entries for
- each action taken).
-
- You don't have to tell us your actual name when filing a problem report,
- but please use a nickname so we can differentiate between your messages
- and the ones entered by other "anonymous" users that may respond to your
- request if they have the same problem or already found a solution.
-
- Please also check the status of your request a few days after submitting
- it, as we may request additional information. If you use a SF id, you
- should automatically get a mail when someone responds to your request.
-
- The appendix of the Privoxy User Manual also has helpful information on
- understanding actions, and action debugging.
-
- --------------------------------------------------------------------------
-
- 11.3. Request New Features
-
- You are welcome to submit ideas on new features or other proposals for
- improvement through our feature request tracker at
- http://sourceforge.net/tracker/?atid=361118&group_id=11118.
-
- --------------------------------------------------------------------------
-
- 11.4. Other
-
- For any other issues, feel free to use the mailing lists. Technically
- interested users and people who wish to contribute to the project are also
- welcome on the developers list! You can find an overview of all
- Privoxy-related mailing lists, including list archives, at:
- http://sourceforge.net/mail/?group_id=11118.
-
- --------------------------------------------------------------------------
-
-12. Privoxy Copyright, License and History
-
- Copyright (c) 2001-2008 by Privoxy Developers
- <ijbswa-developers@lists.sourceforge.net>
-
- Some source code is based on code Copyright (c) 1997 by Anonymous Coders
- and Junkbusters, Inc. and licensed under the GNU General Public License.
-
- --------------------------------------------------------------------------
-
- 12.1. License
-
- Privoxy is free software; you can redistribute it and/or modify it under
- the terms of the GNU General Public License, version 2, as published by
- the Free Software Foundation.
-
- This program is distributed in the hope that it will be useful, but
- WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
- or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
- for more details, which is available from the Free Software Foundation,
- Inc, 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA
-
- You should have received a copy of the GNU General Public License along
- with this program; if not, write to the
-
- Free Software
- Foundation, Inc. 51 Franklin Street, Fifth Floor
- Boston, MA 02110-1301
- USA
-
- --------------------------------------------------------------------------
-
- 12.2. History
-
- A long time ago, there was the Internet Junkbuster, by Anonymous Coders
- and Junkbusters Corporation. This saved many users a lot of pain in the
- early days of web advertising and user tracking.
-
- But the web, its protocols and standards, and with it, the techniques for
- forcing ads on users, give up autonomy over their browsing, and for
- tracking them, keeps evolving. Unfortunately, the Internet Junkbuster did
- not. Version 2.0.2, published in 1998, was (and is) the last official
- release available from Junkbusters Corporation. Fortunately, it had been
- released under the GNU GPL, which allowed further development by others.
-
- So Stefan Waldherr started maintaining an improved version of the
- software, to which eventually a number of people contributed patches. It
- could already replace banners with a transparent image, and had a first
- version of pop-up killing, but it was still very closely based on the
- original, with all its limitations, such as the lack of HTTP/1.1 support,
- flexible per-site configuration, or content modification. The last release
- from this effort was version 2.0.2-10, published in 2000.
-
- Then, some developers picked up the thread, and started turning the
- software inside out, upside down, and then reassembled it, adding many new
- features along the way.
-
- The result of this is Privoxy, whose first stable version, 3.0, was
- released August, 2002.
-
- --------------------------------------------------------------------------
-
- 12.3. Authors
-
- Current Privoxy Team:
-
- Fabian Keil, lead developer
- David Schmidt, developer
-
- Hal Burgiss
- Gerry Murphy
- Roland Rosenfeld
- Jörg Strohmayer
-
- Former Privoxy Team Members:
-
- Johny Agotnes
- Rodrigo Barbosa
- Moritz Barsnick
- Ian Cummings
- Brian Dessent
- Jon Foster
- Karsten Hopp
- Alexander Lazic
- Daniel Leite
- Gábor Lipták
- Adam Lock
- Guy Laroche
- Mark Martinec
- Justin McMurtry
- Andreas Oesterhelt
- Haroon Rafique
- Georg Sauthoff
- Thomas Steudten
- Rodney Stromlund
- Sviatoslav Sviridov
- Sarantis Paskalis
- Stefan Waldherr
-
- Thanks to the many people who have tested Privoxy, reported bugs, provided
- patches, made suggestions or contributed in some way. These include (in
- alphabetical order):
-
- Ken Arromdee
- Devin Bayer
- Gergely Bor
- Reiner Buehl
- Andrew J. Caines
- Clifford Caoile
- Frédéric Crozat
- Michael T. Davis
- Mattes Dolak
- Peter E.
- Florian Effenberger
- Markus Elfring
- Dean Gaudet
- Stephen Gildea
- Daniel Griscom
- Felix Gröbert
- Aaron Hamid
- Darel Henman
- Magnus Holmgren
- Ralf Horstmann
- Stefan Huehner
- Peter Hyman
- Derek Jennings
- Petr Kadlec
- David Laight
- Bert van Leeuwen
- Don Libes
- Paul Lieverse
- Toby Lyward
- Wil Mahan
- Jindrich Makovicka
- David Mediavilla
- Raphael Moll
- Amuro Namie
- Adam Piggott
- Dan Price
- Lee R.
- Roberto Ragusa
- Félix Rauch
- Maynard Riley
- Chung-chieh Shan
- Spinor S.
- Bart Schelstraete
- Oliver Stoeneberg
- Peter Thoenen
- Martin Thomas
- Song Weijia
- Jörg Weinmann
- Darren Wiebe
- Bobby G. Vinyard
- Anduin Withers
- Oliver Yeoh
- Jamie Zawinski
-
- Privoxy is based in part on code originally developed by Junkbusters Corp.
- and Anonymous Coders.
-
- Privoxy heavily relies on Philip Hazel's PCRE.
-
- The code to filter compressed content makes use of zlib which is written
- by Jean-loup Gailly and Mark Adler.
-
- On systems that lack snprintf(), Privoxy is using a version written by
- Mark Martinec. On systems that lack strptime(), Privoxy is using the one
- from the GNU C Library written by Ulrich Drepper.
-
- --------------------------------------------------------------------------
-
-13. See Also
-
- Other references and sites of interest to Privoxy users:
-
- http://www.privoxy.org/, the Privoxy Home page.
-
- http://www.privoxy.org/faq/, the Privoxy FAQ.
-
- http://sourceforge.net/projects/ijbswa/, the Project Page for Privoxy on
- SourceForge.
-
- http://config.privoxy.org/, the web-based user interface. Privoxy must be
- running for this to work. Shortcut: http://p.p/
-
- http://sourceforge.net/tracker/?group_id=11118&atid=460288, to submit
- "misses" and other configuration related suggestions to the developers.
-
- http://www.junkbusters.com/ht/en/cookies.html, an explanation how cookies
- are used to track web users.
-
- http://www.junkbusters.com/ijb.html, the original Internet Junkbuster.
-
- http://privacy.net/, a useful site to check what information about you is
- leaked while you browse the web.
-
- http://www.squid-cache.org/, a popular caching proxy, which is often used
- together with Privoxy.
-
- http://www.pps.jussieu.fr/~jch/software/polipo/, Polipo is a caching proxy
- with advanced features like pipelining, multiplexing and caching of
- partial instances. In many setups it can be used as Squid replacement.
-
- http://tor.eff.org/, Tor can help anonymize web browsing, web publishing,
- instant messaging, IRC, SSH, and other applications.
-
- http://www.privoxy.org/developer-manual/, the Privoxy developer manual.
-
- --------------------------------------------------------------------------
-
-14. Appendix
-
- 14.1. Regular Expressions
-
- Privoxy uses Perl-style "regular expressions" in its actions files and
- filter file, through the PCRE and PCRS libraries.
-
- If you are reading this, you probably don't understand what "regular
- expressions" are, or what they can do. So this will be a very brief
- introduction only. A full explanation would require a book ;-)
-
- Regular expressions provide a language to describe patterns that can be
- run against strings of characters (letter, numbers, etc), to see if they
- match the string or not. The patterns are themselves (sometimes complex)
- strings of literal characters, combined with wild-cards, and other special
- characters, called meta-characters. The "meta-characters" have special
- meanings and are used to build complex patterns to be matched against.
- Perl Compatible Regular Expressions are an especially convenient "dialect"
- of the regular expression language.
-
- To make a simple analogy, we do something similar when we use wild-card
- characters when listing files with the dir command in DOS. *.* matches all
- filenames. The "special" character here is the asterisk which matches any
- and all characters. We can be more specific and use ? to match just
- individual characters. So "dir file?.text" would match "file1.txt",
- "file2.txt", etc. We are pattern matching, using a similar technique to
- "regular expressions"!
-
- Regular expressions do essentially the same thing, but are much, much more
- powerful. There are many more "special characters" and ways of building
- complex patterns however. Let's look at a few of the common ones, and then
- some examples:
-
- . - Matches any single character, e.g. "a", "A", "4", ":", or "@".
-
- ? - The preceding character or expression is matched ZERO or ONE times.
- Either/or.
-
- + - The preceding character or expression is matched ONE or MORE times.
-
- * - The preceding character or expression is matched ZERO or MORE times.
-
- \ - The "escape" character denotes that the following character should be
- taken literally. This is used where one of the special characters (e.g.
- ".") needs to be taken literally and not as a special meta-character.
- Example: "example\.com", makes sure the period is recognized only as a
- period (and not expanded to its meta-character meaning of any single
- character).
-
- [ ] - Characters enclosed in brackets will be matched if any of the
- enclosed characters are encountered. For instance, "[0-9]" matches any
- numeric digit (zero through nine). As an example, we can combine this with
- "+" to match any digit one of more times: "[0-9]+".
-
- ( ) - parentheses are used to group a sub-expression, or multiple
- sub-expressions.
-
- | - The "bar" character works like an "or" conditional statement. A match
- is successful if the sub-expression on either side of "|" matches. As an
- example: "/(this|that) example/" uses grouping and the bar character and
- would match either "this example" or "that example", and nothing else.
-
- These are just some of the ones you are likely to use when matching URLs
- with Privoxy, and is a long way from a definitive list. This is enough to
- get us started with a few simple examples which may be more illuminating:
-
- /.*/banners/.* - A simple example that uses the common combination of "."
- and "*" to denote any character, zero or more times. In other words, any
- string at all. So we start with a literal forward slash, then our regular
- expression pattern (".*") another literal forward slash, the string
- "banners", another forward slash, and lastly another ".*". We are building
- a directory path here. This will match any file with the path that has a
- directory named "banners" in it. The ".*" matches any characters, and this
- could conceivably be more forward slashes, so it might expand into a much
- longer looking path. For example, this could match:
- "/eye/hate/spammers/banners/annoy_me_please.gif", or just
- "/banners/annoying.html", or almost an infinite number of other possible
- combinations, just so it has "banners" in the path somewhere.
-
- And now something a little more complex:
-
- /.*/adv((er)?ts?|ertis(ing|ements?))?/ - We have several literal forward
- slashes again ("/"), so we are building another expression that is a file
- path statement. We have another ".*", so we are matching against any
- conceivable sub-path, just so it matches our expression. The only true
- literal that must match our pattern is adv, together with the forward
- slashes. What comes after the "adv" string is the interesting part.
-
- Remember the "?" means the preceding expression (either a literal
- character or anything grouped with "(...)" in this case) can exist or not,
- since this means either zero or one match. So
- "((er)?ts?|ertis(ing|ements?))" is optional, as are the individual
- sub-expressions: "(er)", "(ing|ements?)", and the "s". The "|" means "or".
- We have two of those. For instance, "(ing|ements?)", can expand to match
- either "ing" OR "ements?". What is being done here, is an attempt at
- matching as many variations of "advertisement", and similar, as possible.
- So this would expand to match just "adv", or "advert", or "adverts", or
- "advertising", or "advertisement", or "advertisements". You get the idea.
- But it would not match "advertizements" (with a "z"). We could fix that by
- changing our regular expression to:
- "/.*/adv((er)?ts?|erti(s|z)(ing|ements?))?/", which would then match
- either spelling.
-
- /.*/advert[0-9]+\.(gif|jpe?g) - Again another path statement with forward
- slashes. Anything in the square brackets "[ ]" can be matched. This is
- using "0-9" as a shorthand expression to mean any digit one through nine.
- It is the same as saying "0123456789". So any digit matches. The "+" means
- one or more of the preceding expression must be included. The preceding
- expression here is what is in the square brackets -- in this case, any
- digit one through nine. Then, at the end, we have a grouping:
- "(gif|jpe?g)". This includes a "|", so this needs to match the expression
- on either side of that bar character also. A simple "gif" on one side, and
- the other side will in turn match either "jpeg" or "jpg", since the "?"
- means the letter "e" is optional and can be matched once or not at all. So
- we are building an expression here to match image GIF or JPEG type image
- file. It must include the literal string "advert", then one or more
- digits, and a "." (which is now a literal, and not a special character,
- since it is escaped with "\"), and lastly either "gif", or "jpeg", or
- "jpg". Some possible matches would include: "//advert1.jpg",
- "/nasty/ads/advert1234.gif", "/banners/from/hell/advert99.jpg". It would
- not match "advert1.gif" (no leading slash), or "/adverts232.jpg" (the
- expression does not include an "s"), or "/advert1.jsp" ("jsp" is not in
- the expression anywhere).
-
- We are barely scratching the surface of regular expressions here so that
- you can understand the default Privoxy configuration files, and maybe use
- this knowledge to customize your own installation. There is much, much
- more that can be done with regular expressions. Now that you know enough
- to get started, you can learn more on your own :/
-
- More reading on Perl Compatible Regular expressions:
- http://perldoc.perl.org/perlre.html
-
- For information on regular expression based substitutions and their
- applications in filters, please see the filter file tutorial in this
- manual.
-
- --------------------------------------------------------------------------
-
- 14.2. Privoxy's Internal Pages
-
- Since Privoxy proxies each requested web page, it is easy for Privoxy to
- trap certain special URLs. In this way, we can talk directly to Privoxy,
- and see how it is configured, see how our rules are being applied, change
- these rules and other configuration options, and even turn Privoxy's
- filtering off, all with a web browser.
-
- The URLs listed below are the special ones that allow direct access to
- Privoxy. Of course, Privoxy must be running to access these. If not, you
- will get a friendly error message. Internet access is not necessary
- either.
-
- * Privoxy main page:
-
- http://config.privoxy.org/
-
- There is a shortcut: http://p.p/ (But it doesn't provide a fall-back
- to a real page, in case the request is not sent through Privoxy)
-
- * Show information about the current configuration, including viewing
- and editing of actions files:
-
- http://config.privoxy.org/show-status
-
- * Show the source code version numbers:
-
- http://config.privoxy.org/show-version
-
- * Show the browser's request headers:
-
- http://config.privoxy.org/show-request
-
- * Show which actions apply to a URL and why:
-
- http://config.privoxy.org/show-url-info
-
- * Toggle Privoxy on or off. This feature can be turned off/on in the
- main config file. When toggled "off", "Privoxy" continues to run, but
- only as a pass-through proxy, with no actions taking place:
-
- http://config.privoxy.org/toggle
-
- Short cuts. Turn off, then on:
-
- http://config.privoxy.org/toggle?set=disable
-
- http://config.privoxy.org/toggle?set=enable
-
- These may be bookmarked for quick reference. See next.
-
- --------------------------------------------------------------------------
-
- 14.2.1. Bookmarklets
-
- Below are some "bookmarklets" to allow you to easily access a "mini"
- version of some of Privoxy's special pages. They are designed for MS
- Internet Explorer, but should work equally well in Netscape, Mozilla, and
- other browsers which support JavaScript. They are designed to run directly
- from your bookmarks - not by clicking the links below (although that
- should work for testing).
-
- To save them, right-click the link and choose "Add to Favorites" (IE) or
- "Add Bookmark" (Netscape). You will get a warning that the bookmark "may
- not be safe" - just click OK. Then you can run the Bookmarklet directly
- from your favorites/bookmarks. For even faster access, you can put them on
- the "Links" bar (IE) or the "Personal Toolbar" (Netscape), and run them
- with a single click.
-
- * Privoxy - Enable
-
- * Privoxy - Disable
-
- * Privoxy - Toggle Privoxy (Toggles between enabled and disabled)
-
- * Privoxy- View Status
-
- * Privoxy - Why?
-
- Credit: The site which gave us the general idea for these bookmarklets is
- www.bookmarklets.com. They have more information about bookmarklets.
-
- --------------------------------------------------------------------------
-
- 14.3. Chain of Events
-
- Let's take a quick look at how some of Privoxy's core features are
- triggered, and the ensuing sequence of events when a web page is requested
- by your browser:
-
- * First, your web browser requests a web page. The browser knows to send
- the request to Privoxy, which will in turn, relay the request to the
- remote web server after passing the following tests:
-
- * Privoxy traps any request for its own internal CGI pages (e.g
- http://p.p/) and sends the CGI page back to the browser.
-
- * Next, Privoxy checks to see if the URL matches any "+block" patterns.
- If so, the URL is then blocked, and the remote web server will not be
- contacted. "+handle-as-image" and "+handle-as-empty-document" are then
- checked, and if there is no match, an HTML "BLOCKED" page is sent back
- to the browser. Otherwise, if it does match, an image is returned for
- the former, and an empty text document for the latter. The type of
- image would depend on the setting of "+set-image-blocker" (blank,
- checkerboard pattern, or an HTTP redirect to an image elsewhere).
-
- * Untrusted URLs are blocked. If URLs are being added to the trust file,
- then that is done.
-
- * If the URL pattern matches the "+fast-redirects" action, it is then
- processed. Unwanted parts of the requested URL are stripped.
-
- * Now the rest of the client browser's request headers are processed. If
- any of these match any of the relevant actions (e.g.
- "+hide-user-agent", etc.), headers are suppressed or forged as
- determined by these actions and their parameters.
-
- * Now the web server starts sending its response back (i.e. typically a
- web page).
-
- * First, the server headers are read and processed to determine, among
- other things, the MIME type (document type) and encoding. The headers
- are then filtered as determined by the "+crunch-incoming-cookies",
- "+session-cookies-only", and "+downgrade-http-version" actions.
-
- * If the "+kill-popups" action applies, and it is an HTML or JavaScript
- document, the popup-code in the response is filtered on-the-fly as it
- is received.
-
- * If any "+filter" action or "+deanimate-gifs" action applies (and the
- document type fits the action), the rest of the page is read into
- memory (up to a configurable limit). Then the filter rules (from
- default.filter and any other filter files) are processed against the
- buffered content. Filters are applied in the order they are specified
- in one of the filter files. Animated GIFs, if present, are reduced to
- either the first or last frame, depending on the action setting.The
- entire page, which is now filtered, is then sent by Privoxy back to
- your browser.
-
- If neither a "+filter" action or "+deanimate-gifs" matches, then
- Privoxy passes the raw data through to the client browser as it
- becomes available.
-
- * As the browser receives the now (possibly filtered) page content, it
- reads and then requests any URLs that may be embedded within the page
- source, e.g. ad images, stylesheets, JavaScript, other HTML documents
- (e.g. frames), sounds, etc. For each of these objects, the browser
- issues a separate request (this is easily viewable in Privoxy's logs).
- And each such request is in turn processed just as above. Note that a
- complex web page will have many, many such embedded URLs. If these
- secondary requests are to a different server, then quite possibly a
- very differing set of actions is triggered.
-
- NOTE: This is somewhat of a simplistic overview of what happens with each
- URL request. For the sake of brevity and simplicity, we have focused on
- Privoxy's core features only.
-
- --------------------------------------------------------------------------
-
- 14.4. Troubleshooting: Anatomy of an Action
-
- The way Privoxy applies actions and filters to any given URL can be
- complex, and not always so easy to understand what is happening. And
- sometimes we need to be able to see just what Privoxy is doing.
- Especially, if something Privoxy is doing is causing us a problem
- inadvertently. It can be a little daunting to look at the actions and
- filters files themselves, since they tend to be filled with regular
- expressions whose consequences are not always so obvious.
-
- One quick test to see if Privoxy is causing a problem or not, is to
- disable it temporarily. This should be the first troubleshooting step. See
- the Bookmarklets section on a quick and easy way to do this (be sure to
- flush caches afterward!). Looking at the logs is a good idea too. (Note
- that both the toggle feature and logging are enabled via config file
- settings, and may need to be turned "on".)
-
- Another easy troubleshooting step to try is if you have done any
- customization of your installation, revert back to the installed defaults
- and see if that helps. There are times the developers get complaints about
- one thing or another, and the problem is more related to a customized
- configuration issue.
-
- Privoxy also provides the http://config.privoxy.org/show-url-info page
- that can show us very specifically how actions are being applied to any
- given URL. This is a big help for troubleshooting.
-
- First, enter one URL (or partial URL) at the prompt, and then Privoxy will
- tell us how the current configuration will handle it. This will not help
- with filtering effects (i.e. the "+filter" action) from one of the filter
- files since this is handled very differently and not so easy to trap! It
- also will not tell you about any other URLs that may be embedded within
- the URL you are testing. For instance, images such as ads are expressed as
- URLs within the raw page source of HTML pages. So you will only get info
- for the actual URL that is pasted into the prompt area -- not any
- sub-URLs. If you want to know about embedded URLs like ads, you will have
- to dig those out of the HTML source. Use your browser's "View Page Source"
- option for this. Or right click on the ad, and grab the URL.
-
- Let's try an example, google.com, and look at it one section at a time in
- a sample configuration (your real configuration may vary):
-
- Matches for http://www.google.com:
-
- In file: default.action [ View ] [ Edit ]
-
- {+deanimate-gifs {last}
- +fast-redirects {check-decoded-url}
- +filter {refresh-tags}
- +filter {img-reorder}
- +filter {banners-by-size}
- +filter {webbugs}
- +filter {jumping-windows}
- +filter {ie-exploits}
- +hide-forwarded-for-headers
- +hide-from-header {block}
- +hide-referrer {forge}
- +session-cookies-only
- +set-image-blocker {pattern}
- /
-
- { -session-cookies-only }
- .google.com
-
- { -fast-redirects }
- .google.com
-
- In file: user.action [ View ] [ Edit ]
- (no matches in this file)
-
- This is telling us how we have defined our "actions", and which ones match
- for our test case, "google.com". Displayed is all the actions that are
- available to us. Remember, the + sign denotes "on". - denotes "off". So
- some are "on" here, but many are "off". Each example we try may provide a
- slightly different end result, depending on our configuration directives.
-
- The first listing is for our default.action file. The large, multi-line
- listing, is how the actions are set to match for all URLs, i.e. our
- default settings. If you look at your "actions" file, this would be the
- section just below the "aliases" section near the top. This will apply to
- all URLs as signified by the single forward slash at the end of the
- listing -- " / ".
-
- But we have defined additional actions that would be exceptions to these
- general rules, and then we list specific URLs (or patterns) that these
- exceptions would apply to. Last match wins. Just below this then are two
- explicit matches for ".google.com". The first is negating our previous
- cookie setting, which was for "+session-cookies-only" (i.e. not
- persistent). So we will allow persistent cookies for google, at least that
- is how it is in this example. The second turns off any "+fast-redirects"
- action, allowing this to take place unmolested. Note that there is a
- leading dot here -- ".google.com". This will match any hosts and
- sub-domains, in the google.com domain also, such as "www.google.com" or
- "mail.google.com". But it would not match "www.google.de"! So, apparently,
- we have these two actions defined as exceptions to the general rules at
- the top somewhere in the lower part of our default.action file, and
- "google.com" is referenced somewhere in these latter sections.
-
- Then, for our user.action file, we again have no hits. So there is nothing
- google-specific that we might have added to our own, local configuration.
- If there was, those actions would over-rule any actions from previously
- processed files, such as default.action. user.action typically has the
- last word. This is the best place to put hard and fast exceptions,
-
- And finally we pull it all together in the bottom section and summarize
- how Privoxy is applying all its "actions" to "google.com":
-
- Final results:
-
- -add-header
- -block
- -client-header-filter{hide-tor-exit-notation}
- -content-type-overwrite
- -crunch-client-header
- -crunch-if-none-match
- -crunch-incoming-cookies
- -crunch-outgoing-cookies
- -crunch-server-header
- +deanimate-gifs {last}
- -downgrade-http-version
- -fast-redirects
- -filter {js-events}
- -filter {content-cookies}
- -filter {all-popups}
- -filter {banners-by-link}
- -filter {tiny-textforms}
- -filter {frameset-borders}
- -filter {demoronizer}
- -filter {shockwave-flash}
- -filter {quicktime-kioskmode}
- -filter {fun}
- -filter {crude-parental}
- -filter {site-specifics}
- -filter {js-annoyances}
- -filter {html-annoyances}
- +filter {refresh-tags}
- -filter {unsolicited-popups}
- +filter {img-reorder}
- +filter {banners-by-size}
- +filter {webbugs}
- +filter {jumping-windows}
- +filter {ie-exploits}
- -filter {google}
- -filter {yahoo}
- -filter {msn}
- -filter {blogspot}
- -filter {no-ping}
- -force-text-mode
- -handle-as-empty-document
- -handle-as-image
- -hide-accept-language
- -hide-content-disposition
- +hide-forwarded-for-headers
- +hide-from-header {block}
- -hide-if-modified-since
- +hide-referrer {forge}
- -hide-user-agent
- -inspect-jpegs
- -kill-popups
- -limit-connect
- -overwrite-last-modified
- -prevent-compression
- -redirect
- -send-vanilla-wafer
- -send-wafer
- -server-header-filter{xml-to-html}
- -server-header-filter{html-to-xml}
- -session-cookies-only
- +set-image-blocker {pattern}
- -treat-forbidden-connects-like-blocks
-
- Notice the only difference here to the previous listing, is to
- "fast-redirects" and "session-cookies-only", which are activated
- specifically for this site in our configuration, and thus show in the
- "Final Results".
-
- Now another example, "ad.doubleclick.net":
-
- { +block }
- ad*.
-
- { +block }
- .ad.
-
- { +block +handle-as-image }
- .[a-vx-z]*.doubleclick.net
-
- We'll just show the interesting part here - the explicit matches. It is
- matched three different times. Two "+block" sections, and a "+block
- +handle-as-image", which is the expanded form of one of our aliases that
- had been defined as: "+block-as-image". ("Aliases" are defined in the
- first section of the actions file and typically used to combine more than
- one action.)
-
- Any one of these would have done the trick and blocked this as an unwanted
- image. This is unnecessarily redundant since the last case effectively
- would also cover the first. No point in taking chances with these guys
- though ;-) Note that if you want an ad or obnoxious URL to be invisible,
- it should be defined as "ad.doubleclick.net" is done here -- as both a
- "+block" and an "+handle-as-image". The custom alias "+block-as-image"
- just simplifies the process and make it more readable.
-
- One last example. Let's try "http://www.example.net/adsl/HOWTO/". This one
- is giving us problems. We are getting a blank page. Hmmm ...
-
- Matches for http://www.example.net/adsl/HOWTO/:
-
- In file: default.action [ View ] [ Edit ]
-
- {-add-header
- -block
- -client-header-filter{hide-tor-exit-notation}
- -content-type-overwrite
- -crunch-client-header
- -crunch-if-none-match
- -crunch-incoming-cookies
- -crunch-outgoing-cookies
- -crunch-server-header
- +deanimate-gifs
- -downgrade-http-version
- +fast-redirects {check-decoded-url}
- -filter {js-events}
- -filter {content-cookies}
- -filter {all-popups}
- -filter {banners-by-link}
- -filter {tiny-textforms}
- -filter {frameset-borders}
- -filter {demoronizer}
- -filter {shockwave-flash}
- -filter {quicktime-kioskmode}
- -filter {fun}
- -filter {crude-parental}
- -filter {site-specifics}
- -filter {js-annoyances}
- -filter {html-annoyances}
- +filter {refresh-tags}
- -filter {unsolicited-popups}
- +filter {img-reorder}
- +filter {banners-by-size}
- +filter {webbugs}
- +filter {jumping-windows}
- +filter {ie-exploits}
- -filter {google}
- -filter {yahoo}
- -filter {msn}
- -filter {blogspot}
- -filter {no-ping}
- -force-text-mode
- -handle-as-empty-document
- -handle-as-image
- -hide-accept-language
- -hide-content-disposition
- +hide-forwarded-for-headers
- +hide-from-header{block}
- +hide-referer{forge}
- -hide-user-agent
- -inspect-jpegs
- -kill-popups
- -overwrite-last-modified
- +prevent-compression
- -redirect
- -send-vanilla-wafer
- -send-wafer
- -server-header-filter{xml-to-html}
- -server-header-filter{html-to-xml}
- +session-cookies-only
- +set-image-blocker{blank}
- -treat-forbidden-connects-like-blocks }
- /
-
- { +block +handle-as-image }
- /ads
-
- Ooops, the "/adsl/" is matching "/ads" in our configuration! But we did
- not want this at all! Now we see why we get the blank page. It is actually
- triggering two different actions here, and the effects are aggregated so
- that the URL is blocked, and Privoxy is told to treat the block as if it
- were an image. But this is, of course, all wrong. We could now add a new
- action below this (or better in our own user.action file) that explicitly
- un blocks ( "{-block}") paths with "adsl" in them (remember, last match in
- the configuration wins). There are various ways to handle such exceptions.
- Example:
-
- { -block }
- /adsl
-
- Now the page displays ;-) Remember to flush your browser's caches when
- making these kinds of changes to your configuration to insure that you get
- a freshly delivered page! Or, try using Shift+Reload.
-
- But now what about a situation where we get no explicit matches like we
- did with:
-
- { +block +handle-as-image }
- /ads
-
- That actually was very helpful and pointed us quickly to where the problem
- was. If you don't get this kind of match, then it means one of the default
- rules in the first section of default.action is causing the problem. This
- would require some guesswork, and maybe a little trial and error to
- isolate the offending rule. One likely cause would be one of the "+filter"
- actions. These tend to be harder to troubleshoot. Try adding the URL for
- the site to one of aliases that turn off "+filter":
-
- { shop }
- .quietpc.com
- .worldpay.com # for quietpc.com
- .jungle.com
- .scan.co.uk
- .forbes.com
-
- "{ shop }" is an "alias" that expands to "{ -filter -session-cookies-only
- }". Or you could do your own exception to negate filtering:
-
- { -filter }
- # Disable ALL filter actions for sites in this section
- .forbes.com
- developer.ibm.com
- localhost
-
- This would turn off all filtering for these sites. This is best put in
- user.action, for local site exceptions. Note that when a simple domain
- pattern is used by itself (without the subsequent path portion), all
- sub-pages within that domain are included automatically in the scope of
- the action.
-
- Images that are inexplicably being blocked, may well be hitting the
- "+filter{banners-by-size}" rule, which assumes that images of certain
- sizes are ad banners (works well most of the time since these tend to be
- standardized).
-
- "{ fragile }" is an alias that disables most actions that are the most
- likely to cause trouble. This can be used as a last resort for problem
- sites.
-
- { fragile }
- # Handle with care: easy to break
- mail.google.
- mybank.example.com
-
- Remember to flush caches! Note that the mail.google reference lacks the
- TLD portion (e.g. ".com"). This will effectively match any TLD with google
- in it, such as mail.google.de., just as an example.
-
- If this still does not work, you will have to go through the remaining
- actions one by one to find which one(s) is causing the problem.
projects / privoxy.git / blobdiff