Privoxy User Manual Copyright © 2001, 2002 by Privoxy Developers $Id: user-manual.sgml,v 1.117 2002/05/17 13:56:16 oes Exp $ The user manual gives users information on how to install, configure and use Privoxy. Privoxy is a web proxy with advanced filtering capabilities for protecting privacy, filtering web page content, managing cookies, controlling access, and removing ads, banners, pop-ups and other obnoxious Internet junk. Privoxy has a very 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 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, SuSE RPMs and Conectiva 2.1.2. Debian 2.1.3. Windows 2.1.4. Solaris, NetBSD, FreeBSD, HP-UX 2.1.5. OS/2 2.1.6. Max OSX 2.1.7. AmigaOS 2.2. Building from Source 3. Note to Upgraders 4. Quickstart to Using Privoxy 4.1. Quickstart to Ad Blocking 5. Starting Privoxy 5.1. RedHat, Conectiva and Debian 5.2. SuSE 5.3. Windows 5.4. Solaris, NetBSD, FreeBSD, HP-UX and others 5.5. OS/2 5.6. MAX OSX 5.7. AmigaOS 5.8. 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. Configuration and Log File Locations 7.1.1. confdir 7.1.2. logdir 7.1.3. actionsfile 7.1.4. filterfile 7.1.5. logfile 7.1.6. jarfile 7.1.7. trustfile 7.2. Local Set-up Documentation 7.2.1. user-manual 7.2.2. trust-info-url 7.2.3. admin-address 7.2.4. proxy-info-url 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-edit-actions 7.4.5. ACLs: permit-access and deny-access 7.4.6. buffer-limit 7.5. Forwarding 7.5.1. forward 7.5.2. forward-socks4 and forward-socks4a 7.5.3. Advanced Forwarding Examples 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 URLs 8.4. Patterns 8.4.1. The Domain Pattern 8.4.2. The Path Pattern 8.5. Actions 8.5.1. add-header 8.5.2. block 8.5.3. crunch-incoming-cookies 8.5.4. crunch-outgoing-cookies 8.5.5. deanimate-gifs 8.5.6. downgrade-http-version 8.5.7. fast-redirects 8.5.8. filter 8.5.9. handle-as-image 8.5.10. hide-forwarded-for-headers 8.5.11. hide-from-header 8.5.12. hide-referrer 8.5.13. hide-user-agent 8.5.14. kill-popups 8.5.15. limit-connect 8.5.16. prevent-compression 8.5.17. send-vanilla-wafer 8.5.18. send-wafer 8.5.19. session-cookies-only 8.5.20. set-image-blocker 8.5.21. Summary 8.6. Aliases 8.7. Actions Files Tutorial 8.7.1. default.action 8.7.2. user.action 9. The Filter File 9.1. Filter File Tutorial 10. Templates 11. Contacting the Developers, Bug Reporting and Feature Requests 11.1. Get Support 11.2. Report Bugs 11.3. Request New Features 11.4. Report Ads or Other Actions-Related Problems 11.5. 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. Anatomy of an Action 1. Introduction This documentation is included with the current beta version of Privoxy, v.2.9.15, and is mostly complete at this point. The most up to date reference for the time being is still the comments in the source files and in the individual configuration files. Development of version 3.0 is currently nearing completion, and includes many significant changes and enhancements over earlier versions. The target release date for stable v3.0 is "soon" ;-). Since this is a beta version, not all new features are well tested. This documentation may be slightly out of sync as a result (especially with CVS sources). And there may be bugs, though hopefully not many! ------------------------------------------------------------------------------- 1.1. Features In addition to Internet Junkbuster's traditional features of ad and banner blocking and cookie management, Privoxy provides new features, some of them currently under development: * 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 content filtering (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. * HTTP/1.1 compliant (but not all optional 1.1 features are supported). * Support for Perl Compatible Regular Expressions in the configuration files, and generally a more sophisticated and flexible configuration syntax over previous versions. * 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: If you have a previous Junkbuster or Privoxy installation on your system, you will need to remove it. On some platforms, this may be done for you as part of their installation procedure. (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, SuSE RPMs and Conectiva RPMs can be installed with rpm -Uvh privoxy-2.9.15-1.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. Note that SuSE will automatically start Privoxy in the boot process. If you have problems with failed dependencies, try rebuilding the SRC RPM: rpm --rebuild privoxy-2.9.15-1.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, before installing Privoxy. ------------------------------------------------------------------------------- 2.1.2. Debian FIXME. ------------------------------------------------------------------------------- 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. We do not use the registry of Windows. ------------------------------------------------------------------------------- 2.1.4. Solaris, NetBSD, FreeBSD, HP-UX 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. FIXME. ------------------------------------------------------------------------------- 2.1.5. OS/2 First, make sure that no previous installations of Junkbuster and / or Privoxy are left on your system. You can do this by 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. Max OSX Unzip the downloaded package (you can either double-click on the file in the finder, or on the desktop if you downloaded it there). Then, double-click on the package installer icon and follow the installation process. Privoxy will be installed in the subdirectory /Applications/Privoxy.app. Privoxy will set itself up to start automatically on system bring-up via /System/Library/ StartupItems/Privoxy. ------------------------------------------------------------------------------- 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. 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). ------------------------------------------------------------------------------- 2.2. Building from Source The most convenient way to obtain the Privoxy sources is to download the source tarball from our project 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 or simply download the nightly CVS tarball. 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 (either release version or nightly CVS tarball), first unpack the source: tar xzvf privoxy-2.9.15-beta-src* [.tgz or .tar.gz] cd privoxy-2.9.15-beta For retrieving the current CVS sources, you'll need CVS installed. Note that sources from CVS are development quality, and may not be stable, or well tested. To download CVS source: cvs -d:pserver:anonymous@cvs.ijbswa.sourceforge.net:/cvsroot/ijbswa login cvs -z3 -d:pserver:anonymous@cvs.ijbswa.sourceforge.net:/cvsroot/ijbswa co current cd current This will create a directory named current/, which will contain the source tree. Then, in either case, to build from unpacked tarball or CVS source: autoheader autoconf ./configure # (--help to see options) make # (the make from gnu, gmake for *BSD) su make -n install # (to see where all the files will go) make install # (to really install) If you have 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. For more detailed instructions on how to build Redhat and SuSE RPMs, Windows self-extracting installers, building on platforms with special requirements etc, please consult the developer manual. ------------------------------------------------------------------------------- 3. Note to Upgraders There are very significant changes from earlier Junkbuster versions to the current Privoxy. The number, names, syntax, and purposes of configuration files have substantially changed. Junkbuster 2.0.x configuration files will not migrate, Junkbuster 2.9.x and Privoxy configurations will need to be ported. The functionalities of the old blockfile, cookiefile and imagelist are now combined into the "actions files". default.action, is the main actions file. Local exceptions should best be put into user.action. A "filter file" (typically default.filter) is new as of Privoxy 2.9.x, and provides some of the new sophistication (explained below). config is much the same as before. If upgrading from a 2.0.x version, you will have to use the new config files, and possibly adapt any personal rules from your older files. When porting personal rules over from the old blockfile to the new actions files, please note that even the pattern syntax has changed. If upgrading from 2.9.x development versions, it is still recommended to use the new configuration files. A quick list of things to be aware of before upgrading: * The default listening port is now 8118 due to a conflict with another service (NAS). * Some installers may remove earlier versions completely. Save any important configuration files! * Privoxy is controllable with a web browser at the special URL: http:// config.privoxy.org/ (Shortcut: http://p.p/). Many aspects of configuration can be done here, including temporarily disabling Privoxy. * The primary configuration files for cookie management, ad and banner blocking, and many other aspects of Privoxy configuration are the actions files. It is strongly recommended to become familiar with the new actions concept below, before modifying these files. Locally defined rules should go into user.action. * Some installers may not automatically start Privoxy after installation. ------------------------------------------------------------------------------- 4. Quickstart to Using Privoxy * If upgrading, from versions before 2.9.16, please back up any configuration files. See the Note to Upgraders Section. * 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 proxy by setting the proxy configuration for address of 127.0.0.1 and port 8118. (Junkbuster and earlier versions of Privoxy used port 8000.) See the section Starting Privoxy below for more details on this. * Flush your browser's disk and memory caches, to remove any cached ad images. * 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. See the Configuration section for more configuration options, and how to customize your installation. * If you experience ads that slipped through, innocent images that are blocked, or otherwise feel the need to fine-tune Privoxy's behaviour, 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 "Anatomy of an Action" has hints how to debug actions that "misbehave". * Please see the section Contacting the Developers on how to report bugs or problems with websites or to get help. * Now enjoy surfing with enhanced 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 recommeneded. 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. 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. When you connect to a website, the full path of the URL will either match one of the "actions" as defined in Privoxy's configuration, or not. If so, then Privoxy will perform the action accordingly. If not, then nothing special happens. Futhermore, web pages may contain embedded, secondary URLs that your web browser will display as it parses the original page's HTML content. An ad image for instance, is just a 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. The actions we need to know about for ad blocking are: block, handle-as-image, and set-image-blocker: * block - 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. If this is the only action that matches for this particular URL, then Privoxy will display its own BLOCKED page to let you now what has happened. * handle-as-image - forces Privoxy to treat this URL as if it were an image. Privoxy knows about common image types (e.g. GIF), but there are many situations where this does not apply. So we'll force it. This is particularly important for ad blocking, since once we can treat it as an image, we can make more intelligent decisisions on how to handle it. There are some limitations to this though. For instance, you can't just force an image substituion for an entire HTML page in most situations. * 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 either be of a known image type, or match an handle-as-image action. The configuration options on what to display instead of the ad are: pattern - a checkboard 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:// - A redirect to any URL of the user's choosing (advanced usage). 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. 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 Screenshot of Files in Use * You should have an Actions section labeled +block. If not, click the "Edit" button just 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". * 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. ------------------------------------------------------------------------------- 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 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! With Netscape (and Mozilla), this can be set under Edit -> Preferences -> Advanced -> Proxies -> HTTP Proxy. For Internet Explorer: Tools -> Internet Properties -> Connections -> LAN Setting. Then, check "Use Proxy" and fill in the appropriate info (Address: 127.0.0.1, Port: 8118). Include if HTTPS proxy support too. 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. You are now ready to start enjoying the benefits of using Privoxy! Privoxy 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. RedHat, Conectiva and Debian We use a script. Note that RedHat does not start Privoxy upon booting per default. It will use the file /etc/privoxy/config as its main configuration file. FIXME: Debian?? # /etc/rc.d/init.d/privoxy start ------------------------------------------------------------------------------- 5.2. SuSE We use a script. It will use the file /etc/privoxy/config as its main configuration file. Note that SuSE starts Privoxy upon booting your PC. # rcprivoxy 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 upon booting you PC. ------------------------------------------------------------------------------- 5.4. Solaris, NetBSD, FreeBSD, HP-UX and others Example Unix startup command: # /usr/sbin/privoxy /etc/privoxy/config ------------------------------------------------------------------------------- 5.5. OS/2 FIXME. ------------------------------------------------------------------------------- 5.6. MAX OSX FIXME. ------------------------------------------------------------------------------- 5.7. AmigaOS FIXME. ------------------------------------------------------------------------------- 5.8. 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. * 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. ------------------------------------------------------------------------------- 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 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. ------------------------------------------------------------------------------- 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 name and number of configuration files has changed from previous versions, and is subject to change as development progresses. 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 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. * default.filter (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. 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. The actions files and default.filter 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. While under development, the configuration content is subject to change. The below documentation may not be accurate by the time you read this. Also, what constitutes a "default" setting, may change, so please check all your configuration files on important issues. ------------------------------------------------------------------------------- 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. 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. ------------------------------------------------------------------------------- 7.1.1. 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 When development goes modular and multi-user, the blocker, filter, and per-user config will be stored in subdirectories of "confdir". For now, the configuration directory structure is flat, except for confdir/templates, where the HTML templates for CGI output reside (e.g. Privoxy's 404 error page). ------------------------------------------------------------------------------- 7.1.2. 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 ------------------------------------------------------------------------------- 7.1.3. actionsfile Specifies: The actions file(s) to use Type of value: File name, relative to confdir, without the .action suffix Default values: standard # Internal purposes, no editing recommended default # Main actions file user # User customizations Effect if unset: No actions are taken at all. Simple 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 are where all the per site and per URL configuration is done for ad blocking, cookie management, privacy considerations, etc. There is no point in using Privoxy without at least one actions file. ------------------------------------------------------------------------------- 7.1.4. filterfile Specifies: The filter file 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: The filter file contains content modification rules that use regular expressions. These rules permit powerful changes on the content of Web pages, e.g., you could disable your favorite JavaScript annoyances, re-write the actual displayed text, or just have some fun replacing "Microsoft" with "MicroSuck" wherever it appears on a Web page. The +filter{name} actions rely on the relevant filter (name) to be defined in the filter file! A pre-defined filter file called default.filter that contains a bunch of handy filters for common problems is included in the distribution. See the section on the filter action for a list. ------------------------------------------------------------------------------- 7.1.5. logfile Specifies: The log file to use Type of value: File name, relative to logdir Default value: logfile (Unix) or privoxy.log (Windows) Effect if unset: No log file is used, all log messages go to the console (stderr). Notes: The windows version will additionally log to the console. 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) but in most cases you probably will never look at it. 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, a logrotate script has been included. On SuSE Linux systems, you can place a line like "/var/log/privoxy.* +1024k 644 nobody.nogroup" in /etc/logfiles, with the effect that cron.daily will automatically archive, gzip, and empty the log, when it exceeds 1M size. Any log files must be writable by whatever user Privoxy is being run as (default on UNIX, user id is "privoxy"). ------------------------------------------------------------------------------- 7.1.6. jarfile Specifies: The file to store intercepted cookies in Type of value: File name, relative to logdir Default value: jarfile (Unix) or privoxy.jar (Windows) Effect if unset: Intercepted cookies are not stored at all. Notes: The jarfile may grow to ridiculous sizes over time. ------------------------------------------------------------------------------- 7.1.7. trustfile Specifies: 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 whole trust mechanism is turned off. 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 named in the trustfile. You can also mark sites as trusted referrers (with +), with the effect that access to untrusted sites will be granted, if a link from a trusted referrer was used. The link target will then be added to the "trustfile". Possible applications include limiting Internet access for children. If you use + operator in the trust file, it may grow considerably over time. ------------------------------------------------------------------------------- 7.2. 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. ------------------------------------------------------------------------------- 7.2.1. 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 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. For multi-user setups, you could provide a copy on a local webserver for all your users and use the corresponding URL here. Examples: Unix, in local filesystem: user-manual file:///usr/share/doc/privoxy-2.9.15/user-manual/ Any platform, on local webserver (called "local-webserver"): user-manual http://local-webserver/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. | +-----------------------------------------------------------------+ ------------------------------------------------------------------------------- 7.2.2. 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 URL 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 above.) 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! ------------------------------------------------------------------------------- 7.2.3. admin-address Specifies: An email address to reach the proxy 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. ------------------------------------------------------------------------------- 7.2.4. 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 ;-) ------------------------------------------------------------------------------- 7.3. 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 to the logfile. Type of value: Integer values Default value: 12289 (i.e.: URLs plus informational and warning messages) Effect if unset: Nothing gets logged. Notes: The available debug levels are: debug 1 # show each GET/POST/CONNECT request debug 2 # show each connection status debug 4 # show I/O status debug 8 # show header parsing debug 16 # log all data into the logfile debug 32 # debug force feature debug 64 # debug regular expression filter debug 128 # debug fast redirects debug 256 # debug GIF de-animation debug 512 # Common Log Format debug 1024 # debug kill pop-ups 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 highly 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). The reporting of fatal errors (i.e. ones which crash Privoxy) is always on and cannot be disabled. If you want to use CLF (Common Log Format), you should set "debug 512" ONLY and not enable anything else. ------------------------------------------------------------------------------- 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 debug purposes and you should never need to use it. 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 "ACLs" below), or a firewall. 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. behave like a normal, content-neutral proxy where all ad blocking, filtering, etc are disabled. See enable-remote-toggle below. This is not really useful anymore, since toggling is much easier via the web interface than via editing the conf file. 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: 1 Effect if unset: The web-based toggle feature is disabled. Notes: When toggled off, Privoxy acts like a normal, content-neutral proxy, i.e. it acts as if none of the actions applied to any URL. For the time being, 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 you must have compiled Privoxy with support for this feature, otherwise this option has no effect. ------------------------------------------------------------------------------- 7.4.4. enable-edit-actions Specifies: Whether or not the web-based actions file editor may be used Type of value: 0 or 1 Default value: 1 Effect if unset: The web-based actions file editor is disabled. Notes: For the time being, 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. So this option is not recommended for multi-user environments with untrusted users. Note that you must have compiled Privoxy with support for this feature, otherwise this option has no effect. ------------------------------------------------------------------------------- 7.4.5. 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 this proxy 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, then the Privoxy talks only 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. 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: 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 www.dirty-stuff.example.com: permit-access 192.168.45.64/26 deny-access 192.168.45.73 www.dirty-stuff.example.com ------------------------------------------------------------------------------- 7.4.6. 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. It can be used to better protect privacy and confidentiality when accessing specific domains by routing requests to those domains through an anonymous public proxy (see e.g. http://www.multiproxy.org/anon_list.htm) Or to use a caching proxy to speed up browsing. Or chaining to a parent proxy may be necessary because the machine that Privoxy runs on has no direct Internet access. 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_domain[:port] http_parent[/port] Where target_domain is a domain name pattern (see the chapter on domain matching in the default.action file), http_parent is the address of the parent HTTP proxy as an IP addresses in dotted decimal notation or as a valid DNS name (or "." to denote "no 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 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 anonymizing proxy, except SSL on port 443 (which it doesn't handle): forward .* anon-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.example-isp.net:8000 forward .example-isp.net . ------------------------------------------------------------------------------- 7.5.2. forward-socks4 and forward-socks4a Specifies: Through which SOCKS proxy (and to which parent HTTP proxy) specific requests should be routed. Type of value: target_domain[:port] socks_proxy[/port] http_parent[/port] Where target_domain is a domain name pattern (see the chapter on domain matching in the default.action file), 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.example-isp.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 . ------------------------------------------------------------------------------- 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.net. And host-b has a PPP connection to isp-b.net. Both run Privoxy. Their forwarding configuration can look like this: host-a: forward .*. . forward .isp-b.net host-b:8118 host-b: forward .*. . forward .isp-a.net 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 chain 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. ------------------------------------------------------------------------------- 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 determine 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 three such files included with Privoxy (as of version 2.9.15), 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 for users everywhere. This is the file that the developers are keeping updated, and making available to users. * 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 by the web based editor, to set various pre-defined sets of rules for the default actions section in default.action. These have increasing levels of aggressiveness and have no influence on your browsing unless you select them explicitly in the editor. It is not recommend to edit this file. The list of actions files to be used are defined in the main configuration file, and are processed in the order they are defined. The content of these can all be viewed and edited from http://config.privoxy.org/show-status. 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 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 that 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, 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. 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 kill popup windows per default, you'll have to make exceptions from that rule for sites that you regularly use and that require popups for actually useful content, 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. 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". If you prefer plain text editing to GUIs, you can of course also directly edit the the actions files. Look at default.action which is richly commented. ------------------------------------------------------------------------------- 8.3. How Actions are Applied to URLs 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 patterns, each on a separate line. To determine which actions apply to a request, the URL of the request is compared to all patterns in each action file file. Every time it matches, the list of applicable actions for the URL is incrementally updated, using the heading of the section in which the pattern is located. If multiple matches for the same URL set the same action differently, the last match wins. If not, the effects are aggregated (e.g. a URL might match both the "+handle-as-image" and "+block" actions). You can trace this process for any given URL by visiting http:// config.privoxy.org/show-url-info. More detail on this is provided in the Appendix, Anatomy of an Action. ------------------------------------------------------------------------------- 8.4. Patterns Generally, a pattern has the form /, where both the and are optional. (This is why the pattern / matches all URLs). 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. www.example.com means exactly the same. For domain-only patterns, the trailing / may be omitted. 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. index.html matches nothing, since it would be interpreted as a domain name and there is no top-level domain called .html. ------------------------------------------------------------------------------- 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 that ENDS in .example.com www. matches any domain that STARTS with www. .example. matches any domain that CONTAINS .example. (Correctly speaking: It matches any FQDN that contains example as a domain.) Additionally, there are wild-cards that you can use in the domain names themselves. They work pretty similar to shell wild-cards: "*" stands for zero or more arbitrary characters, "?" stands for any single character, you can define character classes in square brackets and all of that 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. ------------------------------------------------------------------------------- 8.4.2. The Path Pattern Privoxy uses Perl compatible regular expressions (through the PCRE library) for matching the path. 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:// www.perldoc.com/perl5.6/pod/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. ------------------------------------------------------------------------------- 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. There are three classes of actions: * 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 1.0 } * 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-anonymizing 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 actions always over-ride earlier ones. 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). 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 pattern to match more than one pattern and thus more than one set of actions! 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 obnoxious content Effect: Requests for URLs to which this action applies are blocked, i.e. the requests are not forwarded to the remote server, but answered locally with a substitute page or image, as determined by the handle-as-image and set-image-blocker 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. 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 ------------------------------------------------------------------------------- 8.5.3. crunch-incoming-cookies Typical use: Prevent the web server from setting any 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 cookies. For outgoing cookies, use crunch-outgoing-cookies. Use both to disable 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. Example usage: +crunch-incoming-cookies ------------------------------------------------------------------------------- 8.5.4. crunch-outgoing-cookies Typical use: Prevent the web server from reading any 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 cookies. For incoming cookies, use crunch-incoming-cookies. Use both to disable 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 ------------------------------------------------------------------------------- 8.5.5. 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} ------------------------------------------------------------------------------- 8.5.6. 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 (optional) HTTP/1.1 features are supported yet, so there is a chance you might need this action. Example usage (section): {+downgrade-http-version} problem-host.example.com ------------------------------------------------------------------------------- 8.5.7. fast-redirects Typical use: Fool some click-tracking scripts and speed up indirect links Effect: Cut off all but the last valid URL from requests. Type: Boolean. Parameter: N/A 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://some.place/click-tracker.cgi? target=http://some.where.else. 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 ask 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. It is likely to break some sites. You should expect to need possibly many exceptions to this action, if it is enabled by default in default.action. Some sites just don't work without it. Example usage: {+fast-redirects} ------------------------------------------------------------------------------- 8.5.8. filter Typical use: Get rid of HTML and JavaScript annoyances, banner advertisements (by size), do fun text replacements, etc. Effect: Text documents, including HTML and JavaScript, to which this action applies, are filtered on-the-fly through the specified regular expression based substitutions. Type: Parameterized. Parameter: The name of a filter, as defined in the filter file (typically default.filter, set by the filterfile option in the config file) Notes: For your convenience, there are a bunch of pre-defined filters available in the distribution filter file that you can use. See the example below for a list. This is potentially a very powerful feature! But "rolling your own" filters requires a knowledge of regular expressions and HTML. 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. At this time, Privoxy cannot (yet!) uncompress compressed documents. If you want filtering to work on all documents, even those that would normally be sent compressed, use the prevent-compression action in conjunction with filter. Filtering can achieve some of the effects as the block action, i.e. it can be used to block ads and banners. Feedback with suggestions for new or improved filters is particularly welcome! Example usage (with filters from the distribution default.filter file): +filter{html-annoyances} # Get rid of particularly annoying HTML abuse. +filter{js-annoyances} # Get rid of particularly annoying JavaScript abuse +filter{banners-by-size} # Kill banners by size (very efficient!) +filter{content-cookies} # Kill cookies that come sneaking in the HTML or JS content +filter{popups} # Kill all popups in JS and HTML +filter{webbugs} # Squish WebBugs (1x1 invisible GIFs used for user tracking) +filter{fun} # Text replacements for subversive browsing fun! +filter{frameset-borders} # Give frames a border and make them resizeable +filter{refresh-tags} # Kill automatic refresh tags (for dial-on-demand setups) +filter{nimda} # Remove Nimda (virus) code. +filter{shockwave-flash} # Kill embedded Shockwave Flash objects +filter{crude-parental} # Kill all web pages that contain the words "sex" or "warez" ------------------------------------------------------------------------------- 8.5.9. handle-as-image Typical use: Mark URLs as belonging to images (so they'll be replaced by images if they get blocked) 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, (inline) 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 ------------------------------------------------------------------------------- 8.5.10. hide-forwarded-for-headers Typical use: Improve privacy by hiding the true source of the request Effect: Deletes any existing "X-Forwarded-for:" HTTP header from client requests, and prevents adding a new one. Type: Boolean. Parameter: N/A Notes: It is fairly safe to leave this on. This action is scheduled for improvement: It should be able to generate forged "X-Forwarded-for:" headers using random IP addresses from a specified network, to make successive requests from the same client look like requests from a pool of different users sharing the same proxy. Example usage: +hide-forwarded-for-headers ------------------------------------------------------------------------------- 8.5.11. 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} ------------------------------------------------------------------------------- 8.5.12. 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: + "block" to delete the header completely. + "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: "forge" is the preferred option here, since some servers will not send images back otherwise, in an attempt to prevent their valuable content from being embedded elsewhere (and hence, without being surrounded by their banners). 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/} ------------------------------------------------------------------------------- 8.5.13. hide-user-agent Typical use: 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 breaks many web sites that depend on looking at this header | |in order to customize their content for different browsers | |(which, by the way, is NOT a smart way to do that!). | +-----------------------------------------------------------------+ 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 :-). This action is scheduled for improvement. Example usage: +hide-user-agent{Netscape 6.1 (X11; I; Linux 2.4.18 i686)} ------------------------------------------------------------------------------- 8.5.14. kill-popups Typical use: Eliminate those annoying pop-up windows 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 easily confused with the built-in, hardwired 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{popups} does. 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 is a dangerous business. Many shops and banks rely on pop-ups to display forms, shopping carts etc, and killing only the unwanted pop-ups would require artificial intelligence in Privoxy. 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. Example usage: +kill-popups ------------------------------------------------------------------------------- 8.5.15. limit-connect Typical use: Prevent abuse of Privoxy as a TCP proxy relay 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 can be a big security hole, since CONNECT-enabled proxies can be abused as TCP relays very easily. If you don't know what any of this means, there probably is no reason to change this one, since the default is already very restrictive. 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 (gaping security hole!) ------------------------------------------------------------------------------- 8.5.16. prevent-compression Typical use: Ensure that servers send the content uncompressed, so it can be passed through filters Effect: Adds a header to the request that asks for uncompressed 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 for the filter, deanimate-gifs and kill-popups actions to work, Privoxy needs access to the uncompressed data. Unfortunately, Privoxy can't yet(!) uncompress, filter, and re-compress the content on the fly. So if you want to ensure that all websites, including those that normally compress, can be filtered, you need to use this action. This will slow down transfers from those websites, though. If you use any of the above-mentioned actions, you will typically want to use prevent-compression in conjunction with them. Note that some (rare) ill-configured sites don't handle requests for uncompressed documents correctly (they send an empty document body). If you use prevent-compression per default, you'll have to add exceptions for those sites. See the example for how to do that. Example usage (sections): # Set default: # {+prevent-compression} / # Match all sites # Make exceptions for ill sites: # {-prevent-compression} www.debianhelp.org www.pclinuxonline.com ------------------------------------------------------------------------------- 8.5.17. 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 ------------------------------------------------------------------------------- 8.5.18. 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 ------------------------------------------------------------------------------- 8.5.19. 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. Example usage: +session-cookies-only ------------------------------------------------------------------------------- 8.5.20. 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). 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 devil: +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} ------------------------------------------------------------------------------- 8.5.21. 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. This is likely to change in future versions of Privoxy. 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 mercy-for-cookies = -crunch-all-cookies -session-cookies-only # These aliases define combinations of actions # that are useful for certain types of sites: # fragile = -block -crunch-all-cookies -filter -fast-redirects -hide-referer -kill-popups shop = -crunch-all-cookies -filter{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 .nytimes.com # Shopping sites: # Allow cookies (for setting and retrieving your customer data) # {shop} .quietpc.com .worldpay.com # for quietpc.com .scan.co.uk # These shops require pop-ups: # {shop -kill-popups -filter{popups}} .dabs.com .overclockers.co.uk Aliases like "shop" and "fragile" are often used for "problem" sites that require some actions 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 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 # These aliases define combinations of actions # that are useful for certain types of sites: # fragile = -block -crunch-all-cookies -filter -fast-redirects -hide-referer -kill-popups shop = mercy-for-cookies -filter{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 real need to disable any actions here, but we will do that nonetheless, to have a complete listing for your reference. (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: ########################################################################## { \ -add-header \ -block \ -crunch-incoming-cookies \ -crunch-outgoing-cookies \ +deanimate-gifs \ -downgrade-http-version \ +fast-redirects \ +filter{html-annoyances} \ +filter{js-annoyances} \ -filter{content-cookies} \ +filter{popups} \ +filter{webbugs} \ -filter{refresh-tags} \ -filter{fun} \ +filter{nimda} \ +filter{banners-by-size} \ -filter{shockwave-flash} \ -filter{crude-parental} \ -handle-as-image \ +hide-forwarded-for-headers \ +hide-from-header{block} \ +hide-referrer{forge} \ -hide-user-agent \ -kill-popups \ -limit-connect \ +prevent-compression \ -send-vanilla-wafer \ -send-wafer \ +session-cookies-only \ +set-image-blocker{pattern} \ } / # forward slash will match *all* potential URL patterns. The default behavior is now set. Note that some actions, like not hiding the user agent, are part of a "general policy" that applies universally and won't get any exceptions defined later. Other choices, like not blocking (which is understandably the default!) need exceptions, i.e. we need to specify explicitly what we want to block in later sections. We will also want to make exceptions from our general pop-up-killing, and use our defined aliases for that. 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 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 Then, there are sites which rely on pop-up windows (yuck!) to work. Since we made pop-up-killing our default above, we need to make exceptions now. Mozilla users, who can turn on smart handling of unwanted pop-ups in their browsers, can safely choose -filter{popups} (and -kill-popups) above and hence don't need this section. Anyway, disabling an already disabled action doesn't hurt, so we'll define our exceptions regardless of what was chosen in the defaults section: # These sites require pop-ups too :( # { -kill-popups -filter{popups} } .dabs.com .overclockers.co.uk .deutsche-bank-24.de 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 bs*.einets.com .qkimg.net One of the most important jobs of Privoxy is to block banners. A huge bunch of them are already "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 a bunch of 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 You wouldn't believe 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) 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 .sourceforge.net The actual default.action is of course 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'd maybe 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. 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: # (Re-)define aliases for this file: # {{alias}} -crunch-all-cookies = -crunch-incoming-cookies -crunch-outgoing-cookies mercy-for-cookies = -crunch-all-cookies -session-cookies-only fragile = -block -crunch-all-cookies -filter -fast-redirects -hide-referer -kill-popups shop = mercy-for-cookies -filter{popups} -kill-popups allow-ads = -block -filter{banners-by-size} # (see below) 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 mercy-for-cookies alias defined above does exactly that, i.e. it disables crunching of cookies in any direction, and processing of cookies to make them temporary. { mercy-for-cookies } sunsolve.sun.com slashdot.org .yahoo.com .msdn.microsoft.com .redhat.com Your bank needs popups and is allergic to some filter, but you don't know which, so you disable them all: { -filter -kill-popups } .your-home-banking-site.com While browsing the web with Privoxy you noticed some ads that sneaked through, but you were too lazy to report them through our fine and easy feedback system, so you have added them here: { +block } www.a-popular-site.com/some/unobvious/path another.popular.site.net/more/junk/here/ Note that, assuming the banners in the above example have regular image extensions (most do), +handle-as-image need not be specified, since all URLs ending in these extensions will already have been tagged as images in the relevant section of default.action by now. Then 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: { fragile } .forbes.com You like the "fun" text replacements in default.filter, but it is disabled in the distributed actions file. (My colleagues on the team just don't have a sense of humour, that's why! ;-). 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. Finally, you might think 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} above. ------------------------------------------------------------------------------- 9. The Filter File All text substitutions that can be invoked through the filter action must first be defined in the filter file, which is typically called default.filter and which can be selected through the filterfile config option. Typical reasons for doing such substitutions are to eliminate common annoyances in HTML and JavaScript, such as pop-up windows, exit consoles, crippled windows without navigation tools, the infamous tag etc, to suppress images with certain width and height attributes (standard banner sizes or web-bugs), or just to have fun. The possibilities are endless. Filtering works on any text-based document type, including plain text, HTML, JavaScript, CSS etc. (all text/* MIME types). Substitutions are made at the source level, so if you want to "roll your own" filters, you should be familiar with HTML syntax. 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 the keyword 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. A 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 man page 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" 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|()|$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 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 . You already know what .* means, so the whole pattern translates to: Match from the start of the first " 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