                       Privoxy Frequently Asked Questions

   [Copyright[ (c) 2001-2008 by Privoxy Developers]]

   $Id: faq.txt,v 1.57 2008/01/20 08:42:48 fabiankeil Exp $

   This FAQ gives quick answers to frequently asked questions about Privoxy.
   It is not a substitute for the Privoxy User Manual.

   What is Privoxy?

   Privoxy is a non-caching web proxy with advanced filtering capabilities
   for enhancing privacy, modifying web page data, managing HTTP cookies,
   controlling access, and removing ads, banners, pop-ups and other obnoxious
   Internet junk. Privoxy has a flexible configuration and can be customized
   to suit individual needs and tastes. Privoxy has application for both
   stand-alone systems and multi-user networks.

   Privoxy is based on Internet Junkbuster (tm).

   Please note that this document is a work in progress. This copy represents
   the state at the release of version 3.0.8. You can find the latest version
   of the document at http://www.privoxy.org/faq/. Please see the Contact
   section if you want to contact the developers.

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   Table of Contents

   1. General Information

                1.1. Who should give Privoxy a try?

                1.2. Is Privoxy the best choice for me?

                1.3. What is a "proxy"? How does Privoxy work?

                1.4. Does Privoxy do anything more than ad blocking?

                1.5. What is this new version of "Junkbuster"?

                1.6. Why "Privoxy"? Why change the name from Junkbuster at
                all?

                1.7. How does Privoxy differ from the old Junkbuster?

                1.8. How does Privoxy know what is an ad, and what is not?

                1.9. Can Privoxy make mistakes? This does not sound very
                scientific.

                1.10. Will I have to configure Privoxy before I can use it?

                1.11. Can Privoxy run as a server on a network?

                1.12. My browser does the same things as Privoxy. Why should
                I use Privoxy at all?

                1.13. Why should I trust Privoxy?

                1.14. Is there is a license or fee? What about a warranty?
                Registration?

                1.15. Can Privoxy remove spyware? Adware? Viruses?

                1.16. Can I use Privoxy with other ad-blocking software?

                1.17. I would like to help you, what can I do?

                             1.17.1. Would you like to participate?

                             1.17.2. Contribute!

                             1.17.3. Software

   2. Installation

                2.1. Which browsers are supported by Privoxy?

                2.2. Which operating systems are supported?

                2.3. Can I use Privoxy with my email client?

                2.4. I just installed Privoxy. Is there anything special I
                have to do now?

                2.5. What is the proxy address of Privoxy?

                2.6. I just installed Privoxy, and nothing is happening. All
                the ads are there. What's wrong?

                2.7. I get a "Privoxy is not being used" dummy page although
                Privoxy is running and being used.

   3. Configuration

                3.1. What exactly is an "actions" file?

                3.2. The "actions" concept confuses me. Please list some of
                these "actions".

                3.3. How are actions files configured? What is the easiest
                way to do this?

                3.4. There are several different "actions" files. What are
                the differences?

                3.5. Where can I get updated Actions Files?

                3.6. Can I use my old config files?

                3.7. Why is the configuration so complicated?

                3.8. How can I make my Yahoo/Hotmail/Gmail account work?

                3.9. What's the difference between the "Cautious", "Medium"
                and "Advanced" defaults?

                3.10. Why can I change the configuration with a browser? Does
                that not raise security issues?

                3.11. What is the default.filter file? What is a "filter"?

                3.12. How can I set up Privoxy to act as a proxy for my LAN?

                3.13. Instead of ads, now I get a checkerboard pattern. I
                don't want to see anything.

                3.14. Why would anybody want to see a checkerboard pattern?

                3.15. I see some images being replaced with text instead of
                the checkerboard image. Why and how do I get rid of this?

                3.16. Can Privoxy run as a service on Win2K/NT/XP?

                3.17. How can I make Privoxy work with other proxies like
                Squid or Tor?

                3.18. Can I just set Privoxy to use port 80 and thus avoid
                individual browser configuration?

                3.19. Can Privoxy run as a "transparent" proxy?

                3.20. Can Privoxy run as a "intercepting" proxy?

                3.21. How can I configure Privoxy for use with Outlook
                Express?

                3.22. How can I have separate rules just for HTML mail?

                3.23. I sometimes notice cookies sneaking through. How?

                3.24. Are all cookies bad? Why?

                3.25. How can I allow permanent cookies for my trusted sites?

                3.26. Can I have separate configurations for different users?

                3.27. Can I set-up Privoxy as a whitelist of "good" sites?

                3.28. How can I turn off ad-blocking?

                3.29. How can I have custom template pages, like the BLOCKED
                page?

                3.30. How can I remove the "Go There Anyway" link from the
                BLOCKED page?

   4. Miscellaneous

                4.1. How much does Privoxy slow my browsing down? This has to
                add extra time to browsing.

                4.2. I notice considerable delays in page requests. What's
                wrong?

                4.3. What are "http://config.privoxy.org/" and "http://p.p/"?

                4.4. How can I submit new ads, or report problems?

                4.5. If I do submit missed ads, will they be included in
                future updates?

                4.6. Why doesn't anyone answer my support request?

                4.7. How can I hide my IP address?

                4.8. Can Privoxy guarantee I am anonymous?

                4.9. A test site says I am not using a Proxy.

                4.10. How do I use Privoxy together with Tor?

                4.11. Might some things break because header information or
                content is being altered?

                4.12. Can Privoxy act as a "caching" proxy to speed up web
                browsing?

                4.13. What about as a firewall? Can Privoxy protect me?

                4.14. I have large empty spaces / a checkerboard pattern now
                where ads used to be. Why?

                4.15. How can Privoxy filter Secure (HTTPS) URLs?

                4.16. Privoxy runs as a "server". How secure is it? Do I need
                to take any special precautions?

                4.17. Can I temporarily disable Privoxy?

                4.18. When "disabled" is Privoxy totally out of the picture?

                4.19. How can I tell Privoxy to totally ignore certain sites?

                4.20. My logs show Privoxy "crunches" ads, but also its own
                internal CGI pages. What is a "crunch"?

                4.21. Can Privoxy effect files that I download from a
                webserver? FTP server?

                4.22. I just downloaded a Perl script, and Privoxy altered
                it! Yikes, what is wrong!

                4.23. Should I continue to use a "HOSTS" file for
                ad-blocking?

                4.24. Where can I find more information about Privoxy and
                related issues?

                4.25. I've noticed that Privoxy changes "Microsoft" to
                "MicroSuck"! Why are you manipulating my browsing?

                4.26. Does Privoxy produce "valid" HTML (or XHTML)?

   5. Troubleshooting

                5.1. I cannot connect to any websites. Or, I am getting
                "connection refused" message with every web page. Why?

                5.2. Why am I getting a 503 Error (WSAECONNREFUSED) on every
                page?

                5.3. I just added a new rule, but the steenkin ad is still
                getting through. How?

                5.4. One of my favorite sites does not work with Privoxy.
                What can I do?

                5.5. After installing Privoxy, I have to log in every time I
                start IE. What gives?

                5.6. I cannot connect to any FTP sites. Privoxy is blocking
                me.

                5.7. In Mac OSX, I can't configure Microsoft Internet
                Explorer to use Privoxy as the HTTP proxy.

                5.8. In Mac OSX, I dragged the Privoxy folder to the trash in
                order to uninstall it. Now the finder tells me I don't have
                sufficient privileges to empty the trash.

                5.9. In Mac OSX Panther (10.3), images often fail to load
                and/or I experience random delays in page loading. I'm using
                localhost as my browser's proxy setting.

                5.10. I get a completely blank page at one site. "View
                Source" shows only: <html><body></body></html>. Without
                Privoxy the page loads fine.

                5.11. My logs show many "Unable to get my own hostname"
                lines. Why?

                5.12. When I try to launch Privoxy, I get an error message
                "port 8118 is already in use" (or similar wording). Why?

                5.13. Pages with UTF-8 fonts are garbled.

                5.14. Why are binary files (such as images) corrupted when
                Privoxy is used?

                5.15. What is the "demoronizer" and why is it there?

                5.16. Why do I keep seeing "PrivoxyWindowOpen()" in raw
                source code?

                5.17. I am getting too many DNS errors like "404 No Such
                Domain". Why can't Privoxy do this better?

                5.18. At one site Privoxy just hangs, and starts taking all
                CPU. Why is this?

                5.19. I just installed Privoxy, and all my browsing has
                slowed to a crawl. What gives?

                5.20. Why do my filters work on some sites but not on others?

   6. Contacting the developers, Bug Reporting and Feature Requests

                6.1. Get Support

                6.2. Reporting Problems

                             6.2.1. Reporting Ads or Other Configuration
                             Problems

                             6.2.2. Reporting Bugs

                6.3. Request New Features

                6.4. Other

   7. Privoxy Copyright, License and History

                7.1. License

                7.2. History

1. General Information

    1.1. Who should give Privoxy a try?

   Anyone who is interested in security, privacy, or in finer-grained control
   over their web and Internet experience.

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    1.2. Is Privoxy the best choice for me?

   Privoxy is certainly a good choice, especially for those who want more
   control and security. Those with the willingness to read the documentation
   and the ability to fine-tune their installation will benefit the most.

   One of Privoxy's strengths is that it is highly configurable giving you
   the ability to completely personalize your installation. Being familiar
   with, or at least having an interest in learning about HTTP and other
   networking protocols, HTML, and "Regular Expressions" will be a big plus
   and will help you get the most out of Privoxy. A new installation just
   includes a very basic configuration. The user should take this as a
   starting point only, and enhance it as he or she sees fit. In fact, the
   user is encouraged, and expected to, fine-tune the configuration.

   Much of Privoxy's configuration can be done with a Web browser. But there
   are areas where configuration is done using a text editor to edit
   configuration files. Also note that the web-based action editor doesn't
   use authentication and should only be enabled in environments where all
   clients with access to Privoxy listening port can be trusted.

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    1.3. What is a "proxy"? How does Privoxy work?

   A web proxy is a service, based on a software such as Privoxy, that
   clients (i.e. browsers) can use instead of connecting directly to web
   servers on the Internet. The clients then ask the proxy to fetch the
   objects they need (web pages, images, movies etc) on their behalf, and
   when the proxy has done so, it hands the results back to the client. It is
   a "go-between". See the Wikipedia proxy definition for more.

   There are many reasons to use web proxies, such as security (firewalling),
   efficiency (caching) and others, and there are any number of proxies to
   accommodate those needs.

   Privoxy is a proxy that is primarily focused on privacy protection, ad and
   junk elimination and freeing the user from restrictions placed on his
   activities. Sitting between your browser(s) and the Internet, it is in a
   perfect position to filter outbound personal information that your browser
   is leaking, as well as inbound junk. It uses a variety of techniques to do
   this, all of which are under your complete control via the various
   configuration files and options. Being a proxy also makes it easier to
   share configurations among multiple browsers and/or users.

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    1.4. Does Privoxy do anything more than ad blocking?

   Yes, ad blocking is but one possible use. There are many, many ways
   Privoxy can be used to sanitize and customize web browsing.

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    1.5. What is this new version of "Junkbuster"?

   A long time ago, there was the Internet Junkbuster, by Anonymous Coders
   and Junkbusters Corporation. This saved many users a lot of pain in the
   early days of web advertising and user tracking.

   But the web, its protocols and standards, and with it, the techniques for
   forcing ads on users, give up autonomy over their browsing, and for
   tracking them, keeps evolving. Unfortunately, the Internet Junkbuster did
   not. Version 2.0.2, published in 1998, was (and is) the last official
   release available from Junkbusters Corporation. Fortunately, it had been
   released under the GNU GPL, which allowed further development by others.

   So Stefan Waldherr started maintaining an improved version of the
   software, to which eventually a number of people contributed patches. It
   could already replace banners with a transparent image, and had a first
   version of pop-up killing, but it was still very closely based on the
   original, with all its limitations, such as the lack of HTTP/1.1 support,
   flexible per-site configuration, or content modification. The last release
   from this effort was version 2.0.2-10, published in 2000.

   Then, some developers picked up the thread, and started turning the
   software inside out, upside down, and then reassembled it, adding many new
   features along the way.

   The result of this is Privoxy, whose first stable version, 3.0, was
   released August, 2002.

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    1.6. Why "Privoxy"? Why change the name from Junkbuster at all?

   Though outdated, Junkbusters Corporation continues to offer their original
   version of the Internet Junkbuster, so publishing our Junkbuster-derived
   software under the same name led to confusion.

   There are also potential legal complications from our use of the
   Junkbuster name, which is a registered trademark of Junkbusters
   Corporation. There are, however, no objections from Junkbusters
   Corporation to the Privoxy project itself, and they, in fact, still share
   our ideals and goals.

   The developers also believed that there are so many improvements over the
   original code, that it was time to make a clean break from the past and
   make a name in their own right.

   Privoxy is the "Privacy Enhancing Proxy". Also, its content modification
   and junk suppression gives you, the user, more control, more freedom, and
   allows you to browse your personal and "private edition" of the web.

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    1.7. How does Privoxy differ from the old Junkbuster?

   Privoxy picks up where Junkbuster left off. All the old features remain.
   The new Privoxy still blocks ads and banners, still manages cookies, and
   still helps protect your privacy. But, most of these features have been
   enhanced, and many new ones have been added, all in the same vein.

   Privoxy's new features include:

     * Can be run as an "intercepting" proxy, which obviates the need to
       configure browsers individually.

     * Sophisticated actions and filters for manipulating both server and
       client headers.

     * Can be chained with other proxies.

     * Integrated browser based configuration and control utility at
       http://config.privoxy.org/ (shortcut: http://p.p/). Browser-based
       tracing of rule and filter effects. Remote toggling.

     * Web page filtering (text replacements, removes banners based on size,
       invisible "web-bugs", JavaScript and HTML annoyances, pop-up windows,
       etc.)

     * Modularized configuration that allows for standard settings and user
       settings to reside in separate files, so that installing updated
       actions files won't overwrite individual user settings.

     * Support for Perl Compatible Regular Expressions in the configuration
       files, and a more sophisticated and flexible configuration syntax.

     * Improved cookie management features (e.g. session based cookies).

     * GIF de-animation.

     * Bypass many click-tracking scripts (avoids script redirection).

     * Multi-threaded (POSIX and native threads).

     * User-customizable HTML templates for all proxy-generated pages (e.g.
       "blocked" page).

     * Auto-detection and re-reading of config file changes.

     * Improved signal handling, and a true daemon mode (Unix).

     * Every feature now controllable on a per-site or per-location basis,
       configuration more powerful and versatile over-all.

     * Many smaller new features added, limitations and bugs removed, and
       security holes fixed.

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    1.8. How does Privoxy know what is an ad, and what is not?

   Privoxy's approach to blocking ads is twofold:

   First, there are certain patterns in the locations (URLs) of banner
   images. This applies to both the path (you wouldn't guess how many web
   sites serve their banners from a directory called "banners"!) and the host
   (blocking the big banner hosting services like doublecklick.net already
   helps a lot). Privoxy takes advantage of this fact by using URL patterns
   to sort out and block the requests for things that sound like they would
   be ads or banners.

   Second, banners tend to come in certain sizes. But you can't tell the size
   of an image by its URL without downloading it, and if you do, it's too
   late to save bandwidth. Therefore, Privoxy also inspects the HTML sources
   of web pages while they are loaded, and replaces references to images with
   standard banner sizes by dummy references, so that your browser doesn't
   request them anymore in the first place.

   Both of this involves a certain amount of guesswork and is, of course,
   freely and readily configurable.

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    1.9. Can Privoxy make mistakes? This does not sound very scientific.

   Actually, it's a black art ;-) And yes, it is always possible to have a
   broad rule accidentally block or change something by mistake. You will
   almost surely run into such situations at some point. It is tricky writing
   rules to cover every conceivable possibility, and not occasionally get
   false positives.

   But this should not be a big concern since the Privoxy configuration is
   very flexible, and includes tools to help identify these types of
   situations so they can be addressed as needed, allowing you to customize
   your installation. (See the Troubleshooting section below.)

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    1.10. Will I have to configure Privoxy before I can use it?

   That depends on your expectations. The default installation should give
   you a good starting point, and block most ads and unwanted content, but
   many of the more advanced features are off by default, and require you to
   activate them.

   You do have to set up your browser to use Privoxy (see the Installation
   section below).

   And you will certainly run into situations where there are false
   positives, or ads not being blocked that you may not want to see. In these
   cases, you would certainly benefit by customizing Privoxy's configuration
   to more closely match your individual situation. And we encourage you to
   do this. This is where the real power of Privoxy lies!

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    1.11. Can Privoxy run as a server on a network?

   Yes, Privoxy runs as a server already, and can easily be configured to
   "serve" more than one client. See How can I set up Privoxy to act as a
   proxy for my LAN below.

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    1.12. My browser does the same things as Privoxy. Why should I use Privoxy
    at all?

   Modern browsers do indeed have some of the same functionality as Privoxy.
   Maybe this is adequate for you. But Privoxy is very versatile and
   powerful, and can probably do a number of things your browser just can't.

   In addition, a proxy is good choice if you use multiple browsers, or have
   a LAN with multiple computers since Privoxy can run as a server
   application. This way all the configuration is in one place, and you don't
   have to maintain a similar configuration for possibly many browsers or
   users.

   Note, however, that it's recommended to leverage both your browser's and
   Privoxy's privacy enhancing features at the same time. While your browser
   probably lacks some features Privoxy offers, it should also be able to do
   some things more reliable, for example restricting and suppressing
   JavaScript.

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    1.13. Why should I trust Privoxy?

   The most important reason is because you have access to everything, and
   you can control everything. You can check every line of every
   configuration file yourself. You can check every last bit of source code
   should you desire. And even if you can't read code, there should be some
   comfort in knowing that other people can, and do read it. You can build
   the software from scratch, if you want, so that you know the executable is
   clean, and that it is yours. In fact, we encourage this level of scrutiny.
   It is one reason we use Privoxy ourselves.

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    1.14. Is there is a license or fee? What about a warranty? Registration?

   Privoxy is free software and licensed under the GNU General Public License
   (GPL) version 2. It is free to use, copy, modify or distribute as you wish
   under the terms of this license. Please see the Copyright section for more
   information on the license and copyright. Or the LICENSE file that should
   be included.

   There is no warranty of any kind, expressed, implied or otherwise. That is
   something that would cost real money ;-) There is no registration either.

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    1.15. Can Privoxy remove spyware? Adware? Viruses?

   No, at least not reliably enough to trust it. Privoxy is not designed to
   be a malware removal tool and the default configuration doesn't even try
   to filter out any malware.

   Privoxy could help prevent contact from (known) sites that use such
   tactics with appropriate configuration rules, and thus could conceivably
   prevent contamination from such sites. However, keeping such a
   configuration up to date would require a lot of time and effort that would
   be better spend on keeping your software itself up to date so it doesn't
   have known vulnerabilities.

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    1.16. Can I use Privoxy with other ad-blocking software?

   Privoxy should work fine with other proxies and other software in general.

   But it is probably not necessary to use Privoxy in conjunction with other
   ad-blocking products, and this could conceivably cause undesirable
   results. It might be better to choose one software or the other and work a
   little to tweak its configuration to your liking.

   Note that this is an advice specific to ad blocking.

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    1.17. I would like to help you, what can I do?

      1.17.1. Would you like to participate?

   Well, we always need help. There is something for everybody who wants to
   help us. We welcome new developers, packagers, testers, documentation
   writers or really anyone with a desire to help in any way. You DO NOT need
   to be a "programmer". There are many other tasks available. In fact, the
   programmers often can't spend as much time programming because of some of
   the other, more mundane things that need to be done, like checking the
   Tracker feedback sections.

   So first thing, get an account on SourceForge.net and mail your id to the
   developers mailing list. Then, please read the Developer's Manual, at
   least the pertinent sections.

   You can also start helping out without SourceForge.net account, simply by
   showing up on the mailing list, helping out other users, providing general
   feedback or reporting problems you noticed.

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      1.17.2. Contribute!

   We, of course, welcome donations and could use money for domain
   registering, buying software to test Privoxy with, and, of course, for
   regular world-wide get-togethers (hahaha). If you enjoy the software and
   feel like helping us with a donation, just drop us a note and get your
   name on the list of contributors.

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      1.17.3. Software

   If you are a vendor of a web-related software like a browser, web server
   or proxy, and would like us to ensure that Privoxy runs smoothly with your
   product, you might consider supplying us with a copy or license. We can't,
   however, guarantee that we will fix all potential compatibility issues as
   a result.

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2. Installation

    2.1. Which browsers are supported by Privoxy?

   Any browser that can be configured to use a proxy, which should be
   virtually all browsers, including Firefox, Internet Explorer, Opera, and
   Safari among others. Direct browser support is not an absolute requirement
   since Privoxy runs as a separate application and talks to the browser in
   the standardized HTTP protocol, just like a web server does.

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    2.2. Which operating systems are supported?

   At present, Privoxy is known to run on Windows(95, 98, ME, 2000, XP,
   Vista), GNU/Linux (RedHat, SuSE, Debian, Fedora, Gentoo, Slackware and
   others), Mac OSX, OS/2, AmigaOS, FreeBSD, NetBSD, OpenBSD, Solaris, and
   various other flavors of Unix.

   But any operating system that runs TCP/IP, can conceivably take advantage
   of Privoxy in a networked situation where Privoxy would run as a server on
   a LAN gateway. Then only the "gateway" needs to be running one of the
   above operating systems.

   Source code is freely available, so porting to other operating systems is
   always a possibility.

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    2.3. Can I use Privoxy with my email client?

   As long as there is some way to set a HTTP proxy for the client, then yes,
   any application can be used, whether it is strictly speaking a "browser"
   or not. Though this may not be the best approach for dealing with some of
   the common abuses of HTML in email. See How can I configure Privoxy with
   Outlook Express? below for more on this.

   Be aware that HTML email presents a number of unique security and privacy
   related issues, that can require advanced skills to overcome. The
   developers recommend using email clients that can be configured to convert
   HTML to plain text for these reasons.

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    2.4. I just installed Privoxy. Is there anything special I have to do now?

   All browsers should be told to use Privoxy as a proxy by specifying the
   correct proxy address and port number in the appropriate configuration
   area for the browser. It's possible to combine Privoxy with a packet
   filter to intercept HTTP requests even if the client isn't explicitly
   configured to use Privoxy, but where possible, configuring the client is
   recommended. See the User Manual for more details. You should also flush
   your browser's memory and disk cache to get rid of any cached junk items,
   and remove any stored cookies.

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    2.5. What is the proxy address of Privoxy?

   If you set up the Privoxy to run on the computer you browse from (rather
   than your ISP's server or some networked computer on a LAN), the proxy
   will be on 127.0.0.1 (sometimes referred to as "localhost", which is the
   special name used by every computer on the Internet to refer to itself)
   and the port will be 8118 (unless you used the listen-address config
   option to tell Privoxy to run on a different port).

   When configuring your browser's proxy settings you typically enter the
   word "localhost" or the IP address "127.0.0.1" in the boxes next to "HTTP"
   and "Secure" (HTTPS) and then the number "8118" for "port". This tells
   your browser to send all web requests to Privoxy instead of directly to
   the Internet.

   Privoxy can also be used to proxy for a Local Area Network. In this case,
   your would enter either the IP address of the LAN host where Privoxy is
   running, or the equivalent hostname, e.g. 192.168.1.1. Port assignment
   would be same as above. Note that Privoxy doesn't listen on any LAN
   interfaces by default.

   Privoxy does not currently handle any other protocols such as FTP, SMTP,
   IM, IRC, ICQ, etc.

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    2.6. I just installed Privoxy, and nothing is happening. All the ads are
    there. What's wrong?

   Did you configure your browser to use Privoxy as a proxy? It does not
   sound like it. See above. You might also try flushing the browser's caches
   to force a full re-reading of pages. You can verify that Privoxy is
   running, and your browser is correctly configured by entering the special
   URL: http://p.p/. This should take you to a page titled "This is
   Privoxy.." with access to Privoxy's internal configuration. If you see
   this, then you are good to go. If you receive a page saying "Privoxy is
   not running", then the browser is not set up to use your Privoxy
   installation. If you receive anything else (probably nothing at all), it
   could either be that the browser is not set up correctly, or that Privoxy
   is not running at all. Check the log file. For instructions on starting
   Privoxy and browser configuration, see the chapter on starting Privoxy in
   the User Manual.

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    2.7. I get a "Privoxy is not being used" dummy page although Privoxy is
    running and being used.

   First, make sure that Privoxy is really running and being used by visiting
   http://p.p/. You should see the Privoxy main page. If not, see the chapter
   on starting Privoxy in the User Manual.

   Now if http://p.p/ works for you, but other parts of Privoxy's web
   interface show the dummy page, your browser has cached a redirection it
   encountered before Privoxy was being used. You need to clear your
   browser's cache. Note that shift-reloading the dummy page won't help,
   since that'll only refresh the dummy page, not the redirection that lead
   you there.

   The procedure for clearing the cache varies from browser to browser. For
   example, Mozilla/Netscape users would click Edit --> Preferences -->
   Advanced --> Cache and then click both "Clear Memory Cache" and "Clear
   Disk Cache". In some Firefox versions it's Tools --> Options --> Privacy
   --> Cache and then click "Clear Cache Now".

   --------------------------------------------------------------------------

3. Configuration

    3.1. What exactly is an "actions" file?

   Privoxy utilizes the concept of " actions" that are used to manipulate and
   control web page data. Actions files are where these actions that Privoxy
   could take while processing a certain request, are configured. Typically,
   you would define a set of default actions that apply globally to all URLs,
   then add exceptions to these defaults where needed. There is a wide array
   of actions available that give the user a high degree of control and
   flexibility on how to process each and every web page.

   Actions can be defined on a URL pattern basis, i.e. for single URLs, whole
   web sites, groups or parts thereof etc. Actions can also be grouped
   together and then applied to requests matching one or more patterns. There
   are many possible actions that might apply to any given site. As an
   example, if you are blocking cookies as one of your default actions, but
   need to accept cookies from a given site, you would need to define an
   exception for this site in one of your actions files, preferably in
   user.action.

   --------------------------------------------------------------------------

    3.2. The "actions" concept confuses me. Please list some of these "actions".

   For a comprehensive discussion of the actions concept, please refer to the
   actions file chapter in the User Manual. It includes a list of all actions
   and an actions file tutorial to get you started.

   --------------------------------------------------------------------------

    3.3. How are actions files configured? What is the easiest way to do this?

   Actions files are just text files in a special syntax and can be edited
   with a text editor. But probably the easiest way is to access Privoxy's
   user interface with your web browser at http://config.privoxy.org/
   (Shortcut: http://p.p/) and then select "View & change the current
   configuration" from the menu. Note that this feature must be explicitly
   enabled in the main config file (see enable-edit-actions).

   --------------------------------------------------------------------------

    3.4. There are several different "actions" files. What are the differences?

   Three actions files are being included by the developers, to be used for
   different purposes: These are default.action, the "main" actions file
   which is actively maintained by the Privoxy developers and typically sets
   the default policies, user.action, where users are encouraged to make
   their private customizations, and standard.action, which is for internal
   Privoxy use only. Please see the actions chapter in the User Manual for a
   more detailed explanation.

   Earlier versions included three different versions of the default.action
   file. The new scheme allows for greater flexibility of local
   configuration, and for browser based selection of pre-defined
   "aggressiveness" levels.

   --------------------------------------------------------------------------

    3.5. Where can I get updated Actions Files?

   Based on your feedback and the continuing development, updates of
   default.action will be made available from time to time on the files
   section of our project page.

   If you wish to receive an email notification whenever we release updates
   of Privoxy or the actions file, subscribe to our announce mailing list,
   ijbswa-announce@lists.sourceforge.net.

   --------------------------------------------------------------------------

    3.6. Can I use my old config files?

   The syntax and purpose of configuration files has remained roughly the
   same throughout the 3.x series, but backwards compatibility is not
   guaranteed. Also each release contains updated, "improved" versions and it
   is therefore strongly recommended to install the newer configuration files
   and merge back your modifications.

   --------------------------------------------------------------------------

    3.7. Why is the configuration so complicated?

   "Complicated" is in the eye of the beholder. Those that are familiar with
   some of the underlying concepts, such as regular expression syntax, take
   to it like a fish takes to water. Also, software that tries hard to be
   "user friendly", often lacks sophistication and flexibility. There is
   always that trade-off there between power vs. easy-of-use. Furthermore,
   anyone is welcome to contribute ideas and implementations to enhance
   Privoxy.

   --------------------------------------------------------------------------

    3.8. How can I make my Yahoo/Hotmail/Gmail account work?

   The default configuration shouldn't impact the usability of any of these
   services. It may, however, make all cookies temporary, so that your
   browser will forget your login credentials in between browser sessions. If
   you would like not to have to log in manually each time you access those
   websites, simply turn off all cookie handling for them in the user.action
   file. An example for yahoo might look like:

   # Allow all cookies for Yahoo login:
   #
   { -crunch-incoming-cookies -crunch-outgoing-cookies -session-cookies-only }
   .login.yahoo.com

   These kinds of sites are often quite complex and heavy with Javascript and
   thus "fragile". So if still a problem, we have an alias just for such
   sticky situations:

   # Gmail is a _fragile_ site:
   #
   { fragile }
    # Gmail is ...
    mail.google.com

   Be sure to flush your browser's caches whenever making these kinds of
   changes, just to make sure the changes "take".

   Make sure the domain, host and path are appropriate as well. Your browser
   can tell you where you are specifically and you should use that
   information for your configuration settings. Note that above it is not
   referenced as gmail.com, which is a valid domain name.

   --------------------------------------------------------------------------

    3.9. What's the difference between the "Cautious", "Medium" and "Advanced"
    defaults?

   Configuring Privoxy is not entirely trivial. To help you get started, we
   provide you with three different default action "profiles" in the web
   based actions file editor at http://config.privoxy.org/show-status. See
   the User Manual for a list of actions, and how the default profiles are
   set.

   Where the defaults are likely to break some sites, exceptions for known
   popular "problem" sites are included, but in general, the more aggressive
   your default settings are, the more exceptions you will have to make
   later. New users are best to start off in "Cautious" setting. This is
   safest and will have the fewest problems. See the User Manual for a more
   detailed discussion.

   It should be noted that the "Advanced" profile (formerly known as the
   "Adventuresome" profile) is more aggressive, and will make use of some of
   Privoxy's advanced features. Use at your own risk!

   --------------------------------------------------------------------------

    3.10. Why can I change the configuration with a browser? Does that not raise
    security issues?

   It may seem strange that regular users can edit the config files with
   their browsers, although the whole /etc/privoxy hierarchy belongs to the
   user "privoxy", with only 644 permissions.

   When you use the browser-based editor, Privoxy itself is writing to the
   config files. Because Privoxy is running as the user "privoxy", it can
   update its own config files.

   If you run Privoxy for multiple untrusted users (e.g. in a LAN) or aren't
   entirely in control of your own browser, you will probably want to make
   sure that the the web-based editor and remote toggle features are "off" by
   setting "enable-edit-actions 0" and "enable-remote-toggle 0" in the main
   configuration file.

   As of Privoxy 3.0.7 these options are disabled by default.

   --------------------------------------------------------------------------

    3.11. What is the default.filter file? What is a "filter"?

   The default.filter file is where filters as supplied by the developers are
   defined. Filters are a special subset of actions that can be used to
   modify or remove web page content or headers on the fly. Content filters
   can be applied to anything in the page source, header filters can be
   applied to either server or client headers. Regular expressions are used
   to accomplish this.

   There are a number of pre-defined filters to deal with common annoyances.
   The filters are only defined here, to invoke them, you need to use the
   filter action in one of the actions files. Content filtering is
   automatically disabled for inappropriate MIME types, but if you now better
   than Privoxy what should or should not be filtered you can filter any
   content you like.

   Filters should not be confused with blocks, which is a completely
   different action, and is more typically used to block ads and unwanted
   sites.

   If you are familiar with regular expressions, and HTML, you can look at
   the provided default.filter with a text editor and define your own
   filters. This is potentially a very powerful feature, but requires some
   expertise in both regular expressions and HTML/HTTP. You should place any
   modifications to the default filters, or any new ones you create in a
   separate file, such as user.filter, so they won't be overwritten during
   upgrades. The ability to define multiple filter files in config is a new
   feature as of v. 3.0.5.

   There is no GUI editor option for this part of the configuration, but you
   can disable/enable the various pre-defined filters of the included
   default.filter file with the web-based actions file editor. Note that the
   custom actions editor must be explicitly enabled in the main config file
   (see enable-edit-actions).

   If you intend to develop your own filters, you might want to have a look
   at Privoxy-Filter-Test.

   --------------------------------------------------------------------------

    3.12. How can I set up Privoxy to act as a proxy for my LAN?

   By default, Privoxy only responds to requests from 127.0.0.1 (localhost).
   To have it act as a server for a network, this needs to be changed in the
   main configuration file. Look for the listen-address option, which may be
   commented out with a "#" symbol. Make sure it is uncommented, and assign
   it the address of the LAN gateway interface, and port number to use.
   Assuming your LAN address is 192.168.1.1 and you wish to run Privoxy on
   port 8118, this line should look like:

     listen-address  192.168.1.1:8118

   Save the file, and restart Privoxy. Configure all browsers on the network
   then to use this address and port number.

   Alternately, you can have Privoxy listen on all available interfaces:

     listen-address    :8118

   And then use Privoxy's permit-access feature to limit connections. A
   firewall in this situation is recommended as well.

   The above steps should be the same for any TCP network, regardless of
   operating system.

   If you run Privoxy on a LAN with untrusted users, we recommend that you
   double-check the access control and security options!

   --------------------------------------------------------------------------

    3.13. Instead of ads, now I get a checkerboard pattern. I don't want to see
    anything.

   The replacement for blocked images can be controlled with the
   set-image-blocker action. You have the choice of a checkerboard pattern, a
   transparent 1x1 GIF image (aka "blank"), or a redirect to a custom image
   of your choice. Note that this choice only has effect for images which are
   blocked as images, i.e. whose URLs match both a handle-as-image and block
   action.

   If you want to see nothing, then change the set-image-blocker action to
   "blank". This can be done by editing the user.action file, or through the
   web-based actions file editor.

   --------------------------------------------------------------------------

    3.14. Why would anybody want to see a checkerboard pattern?

   Remember that telling which image is an ad and which isn't, is an educated
   guess. While we hope that the standard configuration is rather smart, it
   will make occasional mistakes. The checkerboard image is visually decent,
   and it shows you where images have been blocked, which can be very helpful
   in case some navigation aid or otherwise innocent image was erroneously
   blocked. It is recommended for new users so they can "see" what is
   happening. Some people might also enjoy seeing how many banners they don't
   have to see.

   --------------------------------------------------------------------------

    3.15. I see some images being replaced with text instead of the checkerboard
    image. Why and how do I get rid of this?

   This happens when the banners are not embedded in the HTML code of the
   page itself, but in separate HTML (sub)documents that are loaded into
   (i)frames or (i)layers, and these external HTML documents are blocked.
   Being non-images they get replaced by a substitute HTML page rather than a
   substitute image, which wouldn't work out technically, since the browser
   expects and accepts only HTML when it has requested an HTML document.

   The substitute page adapts to the available space and shows itself as a
   miniature two-liner if loaded into small frames, or full-blown with a
   large red "BLOCKED" banner if space allows.

   If you prefer the banners to be blocked by images, you must see to it that
   the HTML documents in which they are embedded are not blocked. Clicking
   the "See why" link offered in the substitute page will show you which rule
   blocked the page. After changing the rule and un-blocking the HTML
   documents, the browser will try to load the actual banner images and the
   usual image blocking will (hopefully!) kick in.

   --------------------------------------------------------------------------

    3.16. Can Privoxy run as a service on Win2K/NT/XP?

   Yes. Version 3.0.5 introduces full Windows service functionality. See the
   User Manual for details on how to install and configure Privoxy as a
   service.

   Earlier 3.x versions could run as a system service using srvany.exe. See
   the discussion at
   http://sourceforge.net/tracker/?func=detail&atid=361118&aid=485617&group_id=11118,
   for details, and a sample configuration.

   --------------------------------------------------------------------------

    3.17. How can I make Privoxy work with other proxies like Squid or Tor?

   This can be done and is often useful to combine the benefits of Privoxy
   with those of a another proxy. See the forwarding chapter in the User
   Manual which describes how to do this, and the How do I use Privoxy
   together with Tor section below.

   --------------------------------------------------------------------------

    3.18. Can I just set Privoxy to use port 80 and thus avoid individual
    browser configuration?

   No, its more complicated than that. This only works with special kinds of
   proxies known as "intercepting" proxies (see below).

   --------------------------------------------------------------------------

    3.19. Can Privoxy run as a "transparent" proxy?

   The whole idea of Privoxy is to modify client requests and server
   responses in all sorts of ways and therefore it's not a transparent proxy
   as described in RFC 2616.

   However, some people say "transparent proxy" when they mean "intercepting
   proxy". If you are one of them, please read the next entry.

   --------------------------------------------------------------------------

    3.20. Can Privoxy run as a "intercepting" proxy?

   Privoxy can't intercept traffic itself, but it can handle requests that
   where intercepted and redirected with a packet filter (like PF or
   iptables), as long as the Host header is present.

   As the Host header is required by HTTP/1.1 and as most web sites rely on
   it anyway, this limitation shouldn't be a problem.

   Please refer to your packet filter's documentation to learn how to
   intercept and redirect traffic into Privoxy. Afterward you just have to
   configure Privoxy to accept intercepted requests.

   --------------------------------------------------------------------------

    3.21. How can I configure Privoxy for use with Outlook Express?

   Outlook Express uses Internet Explorer components to both render HTML, and
   fetch any HTTP requests that may be embedded in an HTML email. So however
   you have Privoxy configured to work with IE, this configuration should
   automatically be shared.

   --------------------------------------------------------------------------

    3.22. How can I have separate rules just for HTML mail?

   The short answer is, you can't. Privoxy has no way of knowing which
   particular application makes a request, so there is no way to distinguish
   between web pages and HTML mail. Privoxy just blindly proxies all
   requests. In the case of Outlook Express (see above), OE uses IE anyway,
   and there is no way for Privoxy to ever be able to distinguish between
   them (nor could any other proxy type application for that matter).

   For a good discussion of some of the issues involved (including privacy
   and security issues), see
   http://sourceforge.net/tracker/?func=detail&atid=211118&aid=629518&group_id=11118.

   --------------------------------------------------------------------------

    3.23. I sometimes notice cookies sneaking through. How?

   Cookies can be set in several ways. The classic method is via the
   Set-Cookie HTTP header. This is straightforward, and an easy one to
   manipulate, such as the Privoxy concept of session-cookies-only. There is
   also the possibility of using Javascript to set cookies (Privoxy calls
   these content-cookies). This is trickier because the syntax can vary
   widely, and thus requires a certain amount of guesswork. It is not
   realistic to catch all of these short of disabling Javascript, which would
   break many sites. And lastly, if the cookies are embedded in a HTTPS/SSL
   secure session via Javascript, they are beyond Privoxy's reach.

   All in all, Privoxy can help manage cookies in general, can help minimize
   the loss of privacy posed by cookies, but can't realistically stop all
   cookies.

   --------------------------------------------------------------------------

    3.24. Are all cookies bad? Why?

   No, in fact there are many beneficial uses of cookies. Cookies are just a
   method that browsers can use to store data between pages, or between
   browser sessions. Sometimes there is a good reason for this, and the
   user's life is a bit easier as a result. But there is a long history of
   some websites taking advantage of this layer of trust, and using the data
   they glean from you and your browsing habits for their own purposes, and
   maybe to your potential detriment. Such sites are using you and storing
   their data on your system. That is why the privacy conscious watch from
   whom those cookies come, and why they really need to be there.

   See the Wikipedia cookie definition for more.

   --------------------------------------------------------------------------

    3.25. How can I allow permanent cookies for my trusted sites?

   There are several actions that relate to cookies. The default behavior is
   to allow only "session cookies", which means the cookies only last for the
   current browser session. This eliminates most kinds of abuse related to
   cookies. But there may be cases where you want cookies to last.

   To disable all cookie actions, so that cookies are allowed unrestricted,
   both in and out, for example.com:

 { -crunch-incoming-cookies -crunch-outgoing-cookies -session-cookies-only -filter{content-cookies} }
  .example.com

   Place the above in user.action. Note that some of these may be off by
   default anyway, so this might be redundant, but there is no harm being
   explicit in what you want to happen. user.action includes an alias for
   this situation, called allow-all-cookies.

   --------------------------------------------------------------------------

    3.26. Can I have separate configurations for different users?

   Each instance of Privoxy has its own configuration, including such
   attributes as the TCP port that it listens on. What you can do is run
   multiple instances of Privoxy, each with a unique listen-address
   configuration setting, and configuration path, and then each of these can
   have their own configurations. Think of it as per-port configuration.

   Simple enough for a few users, but for large installations, consider
   having groups of users that might share like configurations.

   --------------------------------------------------------------------------

    3.27. Can I set-up Privoxy as a whitelist of "good" sites?

   Sure. There are a couple of things you can do for simple white-listing.
   Here's one real easy one:

    ############################################################
    # Blacklist
    ############################################################
    { +block }
    / # Block *all* URLs

    ############################################################
    # Whitelist
    ############################################################
    { -block }
     kids.example.com
     toys.example.com
     games.example.com

   This allows access to only those three sites by first blocking all URLs,
   and then subsequently allowing three specific exceptions.

   Another approach is Privoxy's trustfile concept, which incorporates the
   notion of "trusted referrers". See the Trust documentation for details.

   These are fairly simple approaches and are not completely foolproof. There
   are various other configuration options that should be disabled (described
   elsewhere here and in the User Manual) so that users can't modify their
   own configuration and easily circumvent the whitelist.

   --------------------------------------------------------------------------

    3.28. How can I turn off ad-blocking?

   Ad blocking is achieved through a complex application of various Privoxy
   actions. These actions are deployed against simple images, banners, flash
   animations, text pages, JavaScript, pop-ups and pop-unders, etc., so its
   not as simple as just turning one or two actions off. The various actions
   that make up Privoxy ad blocking are hard-coded into the default
   configuration files. It has been assumed that everyone using Privoxy is
   interested in this particular feature.

   If you want to do without this, there are several approaches you can take:
   You can manually undo the many block rules in default.action. Or even
   easier, just create your own default.action file from scratch without the
   many ad blocking rules, and corresponding exceptions. Or lastly, if you
   are not concerned about the additional blocks that are done for privacy
   reasons, you can very easily over-ride all blocking with the following
   very simple rule in your user.action:

    # Unblock everybody, everywhere
    { -block }
    / # UN-Block *all* URLs

   Or even a more comprehensive reversing of various ad related actions:

    # Unblock everybody, everywhere, and turn off appropriate filtering, etc
    { -block \
     -filter{banners-by-size} \
     -filter{banners-by-link} \
     allow-popups \
    }
    / # UN-Block *all* URLs and allow ads

   This last "action" in this compound statement, allow-popups, is an alias
   that disables various pop-up blocking features.

   --------------------------------------------------------------------------

    3.29. How can I have custom template pages, like the BLOCKED page?

   Privoxy "templates" are specialized text files utilized by Privoxy for
   various purposes and can easily be modified using any text editor. All the
   template pages are installed in a sub-directory appropriately named:
   templates. Knowing something about HTML syntax will of course be helpful.

   Be forewarned that the default templates are subject to being overwritten
   during upgrades. You can, however, create completely new templates, place
   them in another directory and specify the alternate path in the main
   config. For details, have a look at the templdir option.

   --------------------------------------------------------------------------

    3.30. How can I remove the "Go There Anyway" link from the BLOCKED page?

   There is more than one way to do it (although Perl is not involved).

   Editing the BLOCKED template page (see above) may dissuade some users, but
   this method is easily circumvented. Where you need this level of control,
   you might want to build Privoxy from source, and disable various features
   that are available as compile-time options. You should configure the
   sources as follows:

    ./configure  --disable-toggle  --disable-editor  --disable-force

   This will create an executable with hard-coded security features so that
   Privoxy does not allow easy bypassing of blocked sites, or changing the
   current configuration via any connected user's web browser.

   Finally, all of these features can also be toggled on/off via options in
   Privoxy's main config file which means you don't have to recompile
   anything.

   --------------------------------------------------------------------------

4. Miscellaneous

    4.1. How much does Privoxy slow my browsing down? This has to add extra time
    to browsing.

   How much of an impact depends on many things, including the CPU of the
   host system, how aggressive the configuration is, which specific actions
   are being triggered, the size of the page, the bandwidth of the
   connection, etc.

   Overall, it should not slow you down any in real terms, and may actually
   help speed things up since ads, banners and other junk are not typically
   being retrieved and displayed. The actual processing time required by
   Privoxy itself for each page, is relatively small in the overall scheme of
   things, and happens very quickly. This is typically more than offset by
   time saved not downloading and rendering ad images and other junk content
   (if ad blocking is being used).

   "Filtering" content via the filter or deanimate-gifs actions may cause a
   perceived slowdown, since the entire document needs to be buffered before
   displaying. And on very large documents, filtering may have some
   measurable impact. How much depends on the page size, the actual
   definition of the filter(s), etc. See below. Most other actions have
   little to no impact on speed.

   Also, when filtering is enabled but zlib support isn't available,
   compression is often disabled (see prevent-compression). This can have an
   impact on speed as well, although it's probably smaller than you might
   think. Again, the page size, etc. will determine how much of an impact.

   --------------------------------------------------------------------------

    4.2. I notice considerable delays in page requests. What's wrong?

   If you use any filter action, such as filtering banners by size, web-bugs
   etc, or the deanimate-gifs action, the entire document must be loaded into
   memory in order for the filtering mechanism to work, and nothing is sent
   to the browser during this time.

   The loading time typically does not really change much in real numbers,
   but the feeling is different, because most browsers are able to start
   rendering incomplete content, giving the user a feeling of "it works".
   This effect is more noticeable on slower dialup connections. Extremely
   large documents may have some impact on the time to load the page where
   there is filtering being done. But overall, the difference should be very
   minimal. If there is a big impact, then probably some other situation is
   contributing (like anti-virus software).

   Filtering is automatically disabled for inappropriate MIME types. But note
   that if the web server mis-reports the MIME type, then content that should
   not be filtered, could be. Privoxy only knows how to differentiate
   filterable content because of the MIME type as reported by the server, or
   because of some configuration setting that enables/disables filtering.

   --------------------------------------------------------------------------

    4.3. What are "http://config.privoxy.org/" and "http://p.p/"?

   http://config.privoxy.org/ is the address of Privoxy's built-in user
   interface, and http://p.p/ is a shortcut for it.

   Since Privoxy sits between your web browser and the Internet, it can
   simply intercept requests for these addresses and answer them with its
   built-in "web server".

   This also makes for a good test for your browser configuration: If
   entering the URL http://config.privoxy.org/ takes you to a page saying
   "This is Privoxy ...", everything is OK. If you get a page saying "Privoxy
   is not working" instead, then your browser didn't use Privoxy for the
   request, hence it could not be intercepted, and you have accessed the real
   web site at config.privoxy.org.

   --------------------------------------------------------------------------

    4.4. How can I submit new ads, or report problems?

   Please see the Contact section for various ways to interact with the
   developers.

   --------------------------------------------------------------------------

    4.5. If I do submit missed ads, will they be included in future updates?

   Whether such submissions are eventually included in the default.action
   configuration file depends on how significant the issue is. We of course
   want to address any potential problem with major, high-profile sites such
   as Google, Yahoo, etc. Any site with global or regional reach, has a good
   chance of being a candidate. But at the other end of the spectrum are any
   number of smaller, low-profile sites such as for local clubs or schools.
   Since their reach and impact are much less, they are best handled by
   inclusion in the user's user.action, and thus would be unlikely to be
   included.

   --------------------------------------------------------------------------

    4.6. Why doesn't anyone answer my support request?

   Rest assured that it has been read and considered. Why it is not answered,
   could be for various reasons, including no one has a good answer for it,
   no one has had time to yet investigate it thoroughly, it has been reported
   numerous times already, or because not enough information was provided to
   help us help you. Your efforts are not wasted, and we do appreciate them.

   --------------------------------------------------------------------------

    4.7. How can I hide my IP address?

   If you run both the browser and Privoxy locally, you cannot hide your IP
   address with Privoxy or ultimately any other software alone. The server
   needs to know your IP address so that it knows where to send the responses
   back.

   There are many publicly usable "anonymous" proxies out there, which
   provide a further level of indirection between you and the web server.

   However, these proxies are called "anonymous" because you don't need to
   authenticate, not because they would offer any real anonymity. Most of
   them will log your IP address and make it available to the authorities in
   case you violate the law of the country they run in. In fact you can't
   even rule out that some of them only exist to *collect* information on
   (those suspicious) people with a more than average preference for privacy.

   If you want to hide your IP address from most adversaries, you should
   consider chaining Privoxy with Tor. The configuration details can be found
   in How do I use Privoxy together with Tor section just below.

   --------------------------------------------------------------------------

    4.8. Can Privoxy guarantee I am anonymous?

   No. Your chances of remaining anonymous are improved, but unless you chain
   Privoxy with Tor or a similar proxy and know what you're doing when it
   comes to configuring the rest of your system, you should assume that
   everything you do on the Web can be traced back to you.

   Privoxy can remove various information about you, and allows you more
   freedom to decide which sites you can trust, and what details you want to
   reveal. But it neither hides your IP address, nor can it guarantee that
   the rest of the system behaves correctly. There are several possibilities
   how a web sites can find out who you are, even if you are using a strict
   Privoxy configuration and chained it with Tor.

   Most of Privoxy's privacy-enhancing features can be easily subverted by an
   insecure browser configuration, therefore you should use a browser that
   can be configured to only execute code from trusted sites, and be careful
   which sites you trust. For example there is no point in having Privoxy
   modify the User-Agent header, if websites can get all the information they
   want through JavaScript, ActiveX, Flash, Java etc.

   A few browsers disclose the user's email address in certain situations,
   such as when transferring a file by FTP. Privoxy does not filter FTP. If
   you need this feature, or are concerned about the mail handler of your
   browser disclosing your email address, you might consider products such as
   NSClean.

   Browsers available only as binaries could use non-standard headers to give
   out any information they can have access to: see the manufacturer's
   license agreement. It's impossible to anticipate and prevent every breach
   of privacy that might occur. The professionally paranoid prefer browsers
   available as source code, because anticipating their behavior is easier.
   Trust the source, Luke!

   --------------------------------------------------------------------------

    4.9. A test site says I am not using a Proxy.

   Good! Actually, they are probably testing for some other kinds of proxies.
   Hiding yourself completely would require additional steps.

   --------------------------------------------------------------------------

    4.10. How do I use Privoxy together with Tor?

   Before you configure Privoxy to use Tor, please follow the User Manual
   chapters 2. Installation and 5. Startup to make sure Privoxy itself is
   setup correctly.

   If it is, refer to Tor's extensive documentation to learn how to install
   Tor, and make sure Tor's logfile says that "Tor has successfully opened a
   circuit" and it "looks like client functionality is working".

   If either Tor or Privoxy isn't working, their combination most likely will
   neither. Testing them on their own will also help you to direct problem
   reports to the right audience. If Privoxy isn't working, don't bother the
   Tor developers. If Tor isn't working, don't send bug reports to the
   Privoxy Team.

   If you verified that Privoxy and Tor are working, it is time to connect
   them. As far as Privoxy is concerned, Tor is just another proxy that can
   be reached by socks4 or socks4a. Most likely you are interested in Tor to
   increase your anonymity level, therefore you should use socks4a, to make
   sure DNS requests are done through Tor and thus invisible to your local
   network.

   Since Privoxy 3.0.5, its main configuration file is already prepared for
   Tor, if you are using a default Tor configuration and run it on the same
   system as Privoxy, you just have to edit the forwarding section and
   uncomment the line:

   #        forward-socks4a             /     127.0.0.1:9050 .


   This is enough to reach the Internet, but additionally you might want to
   uncomment the following forward rules, to make sure your local network is
   still reachable through Privoxy:

   #        forward         192.168.*.*/     .
   #        forward            10.*.*.*/     .
   #        forward           127.*.*.*/     .


   Unencrypted connections to systems in these address ranges will be as
   (un)secure as the local network is, but the alternative is that your
   browser can't reach the network at all. Then again, that may actually be
   desired and if you don't know for sure that your browser has to be able to
   reach the local network, there's no reason to allow it.

   If you want your browser to be able to reach servers in your local network
   by using their names, you will need additional exceptions that look like
   this:

   #        forward           localhost/     .


   Save the modified configuration file and open
   http://config.privoxy.org/show-status/ in your browser, confirm that
   Privoxy has reloaded its configuration and that there are no other forward
   lines, unless you know that you need them. If everything looks good, refer
   to Tor Faq 4.2 to learn how to verify that you are really using Tor.

   Afterward, please take the time to at least skim through the rest of Tor's
   documentation. Make sure you understand what Tor does, why it is no
   replacement for application level security, and why you probably don't
   want to use it for unencrypted logins.

   --------------------------------------------------------------------------

    4.11. Might some things break because header information or content is being
    altered?

   Definitely. It is common for sites to use browser type, browser version,
   HTTP header content, and various other techniques in order to dynamically
   decide what to display and how to display it. What you see, and what I
   see, might be very different. There are many, many ways that this can be
   handled, so having hard and fast rules, is tricky.

   The "User-Agent" is sometimes used in this way to identify the browser,
   and adjust content accordingly.

   Also, different browsers use different encodings of non-English
   characters, certain web servers convert pages on-the-fly according to the
   User Agent header. Giving a "User Agent" with the wrong operating system
   or browser manufacturer causes some sites in these languages to be
   garbled; Surfers to Eastern European sites should change it to something
   closer. And then some page access counters work by looking at the
   "Referer" header; they may fail or break if unavailable. The weather maps
   of Intellicast have been blocked by their server when no "Referer" or
   cookie is provided, is another example. (But you can forge both headers
   without giving information away). There are many other ways things can go
   wrong when trying to fool a web server. The results of which could
   inadvertently cause pages to load incorrectly, partially, or even not at
   all. And there may be no obvious clues as to just what went wrong, or why.
   Nowhere will there be a message that says "Turn off fast-redirects or
   else! "

   Similar thoughts apply to modifying JavaScript, and, to a lesser degree,
   HTML elements.

   If you have problems with a site, you will have to adjust your
   configuration accordingly. Cookies are probably the most likely adjustment
   that may be required, but by no means the only one.

   --------------------------------------------------------------------------

    4.12. Can Privoxy act as a "caching" proxy to speed up web browsing?

   No, it does not have this ability at all. You want something like Squid or
   Polipo for this. And, yes, before you ask, Privoxy can co-exist with other
   kinds of proxies like Squid. See the forwarding chapter in the user manual
   for details.

   --------------------------------------------------------------------------

    4.13. What about as a firewall? Can Privoxy protect me?

   Not in the way you mean, or in the way some firewall vendors claim they
   can. Privoxy can help protect your privacy, but can't protect your system
   from intrusion attempts. It is, of course, perfectly possible to use both.

   --------------------------------------------------------------------------

    4.14. I have large empty spaces / a checkerboard pattern now where ads used
    to be. Why?

   It is technically possible to eliminate banners and ads in a way that
   frees their allocated page space. This could easily be done by blocking
   with Privoxy's filters, and eliminating the entire image references from
   the HTML page source.

   But, this would consume considerably more CPU resources (IOW, slow things
   down), would likely destroy the layout of some web pages which rely on the
   banners utilizing a certain amount of page space, and might fail in other
   cases, where the screen space is reserved (e.g. by HTML tables for
   instance). Also, making ads and banners disappear without any trace
   complicates troubleshooting, and would sooner or later be problematic.

   The better alternative is to instead let them stay, and block the
   resulting requests for the banners themselves as is now the case. This
   leaves either empty space, or the familiar checkerboard pattern.

   So the developers won't support this in the default configuration, but you
   can of course define appropriate filters yourself to achieve this.

   --------------------------------------------------------------------------

    4.15. How can Privoxy filter Secure (HTTPS) URLs?

   Since secure HTTP connections are encrypted SSL sessions between your
   browser and the secure site, and are meant to be reliably secure, there is
   little that Privoxy can do but hand the raw gibberish data though from one
   end to the other unprocessed.

   The only exception to this is blocking by host patterns, as the client
   needs to tell Privoxy the name of the remote server, so that Privoxy can
   establish the connection. If that name matches a host-only pattern, the
   connection will be blocked.

   As far as ad blocking is concerned, this is less of a restriction than it
   may seem, since ad sources are often identifiable by the host name, and
   often the banners to be placed in an encrypted page come unencrypted
   nonetheless for efficiency reasons, which exposes them to the full power
   of Privoxy's ad blocking.

   "Content cookies" (those that are embedded in the actual HTML or JS page
   content, see filter{content-cookies}), in an SSL transaction will be
   impossible to block under these conditions. Fortunately, this does not
   seem to be a very common scenario since most cookies come by traditional
   means.

   --------------------------------------------------------------------------

    4.16. Privoxy runs as a "server". How secure is it? Do I need to take any
    special precautions?

   On Unix-like systems, Privoxy can run as a non-privileged user, which is
   how we recommend it be run. Also, by default Privoxy listens to requests
   from "localhost" only.

   The server aspect of Privoxy is not itself directly exposed to the
   Internet in this configuration. If you want to have Privoxy serve as a LAN
   proxy, this will have to be opened up to allow for LAN requests. In this
   case, we'd recommend you specify only the LAN gateway address, e.g.
   192.168.1.1, in the main Privoxy configuration file and check all access
   control and security options. All LAN hosts can then use this as their
   proxy address in the browser proxy configuration, but Privoxy will not
   listen on any external interfaces. ACLs can be defined in addition, and
   using a firewall is always good too. Better safe than sorry.

   --------------------------------------------------------------------------

    4.17. Can I temporarily disable Privoxy?

   Privoxy doesn't have a transparent proxy mode, but you can toggle off
   blocking and content filtering.

   The easiest way to do that is to point your browser to the remote toggle
   URL: http://config.privoxy.org/toggle.

   See the Bookmarklets section of the User Manual for an easy way to access
   this feature. Note that this is a feature that may need to be enabled in
   the main config file.

   --------------------------------------------------------------------------

    4.18. When "disabled" is Privoxy totally out of the picture?

   No, this just means all optional filtering and actions are disabled.
   Privoxy is still acting as a proxy, but just doing less of the things that
   Privoxy would normally be expected to do. It is still a "middle-man" in
   the interaction between your browser and web sites. See below to bypass
   the proxy.

   --------------------------------------------------------------------------

    4.19. How can I tell Privoxy to totally ignore certain sites?

   Bypassing a proxy, or proxying based on arbitrary criteria, is purely a
   browser configuration issue, not a Privoxy issue. Modern browsers
   typically do have settings for not proxying certain sites. Check your
   browser's help files.

   --------------------------------------------------------------------------

    4.20. My logs show Privoxy "crunches" ads, but also its own internal CGI
    pages. What is a "crunch"?

   A "crunch" simply means Privoxy intercepted something, nothing more. Often
   this is indeed ads or banners, but Privoxy uses the same mechanism for
   trapping requests for its own internal pages. For instance, a request for
   Privoxy's configuration page at: http://config.privoxy.org, is intercepted
   (i.e. it does not go out to the 'net), and the familiar CGI configuration
   is returned to the browser, and the log consequently will show a "crunch".

   Since version 3.0.7, Privoxy will also log the crunch reason. If you are
   using an older version you might want to upgrade.

   --------------------------------------------------------------------------

    4.21. Can Privoxy effect files that I download from a webserver? FTP server?

   From the webserver's perspective, there is no difference between viewing a
   document (i.e. a page), and downloading a file. The same is true of
   Privoxy. If there is a match for a block pattern, it will still be
   blocked, and of course this is obvious.

   Filtering is potentially more of a concern since the results are not
   always so obvious, and the effects of filtering are there whether the file
   is simply viewed, or downloaded. And potentially whether the content is
   some obnoxious advertisement, or Mr. Jimmy's latest/greatest source code
   jewel. Of course, one of these presumably is "bad" content that we don't
   want, and the other is "good" content that we do want. Privoxy is blind to
   the differences, and can only distinguish "good from bad" by the
   configuration parameters we give it.

   Privoxy knows the differences in files according to the "Content Type" as
   reported by the webserver. If this is reported accurately (e.g.
   "application/zip" for a zip archive), then Privoxy knows to ignore these
   where appropriate. Privoxy potentially can filter HTML as well as plain
   text documents, subject to configuration parameters of course. Also,
   documents that are of an unknown type (generally assumed to be
   "text/plain") can be filtered, as will those that might be incorrectly
   reported by the webserver. If such a file is a downloaded file that is
   intended to be saved to disk, then any content that might have been
   altered by filtering, will be saved too, for these (probably rare) cases.

   Note that versions later than 3.0.2 do NOT filter document types reported
   as "text/plain". Prior to this, Privoxy did filter this document type.

   In short, filtering is "ON" if a) the content type as reported by the
   webserver is appropriate and b) the configuration allows it (or at least
   does not disallow it). That's it. There is no magic cookie anywhere to say
   this is "good" and this is "bad". It's the configuration that lets it all
   happen or not.

   If you download text files, you probably do not want these to be filtered,
   particularly if the content is source code, or other critical content.
   Source code sometimes might be mistaken for Javascript (i.e. the kind that
   might open a pop-up window). It is recommended to turn off filtering for
   download sites (particularly if the content may be plain text files and
   you are using version 3.0.2 or earlier) in your user.action file. And
   also, for any site or page where making any changes at all to the content
   is to be avoided.

   Privoxy does not do FTP at all, only HTTP and HTTPS (SSL) protocols, so
   please don't try.

   --------------------------------------------------------------------------

    4.22. I just downloaded a Perl script, and Privoxy altered it! Yikes, what
    is wrong!

   Please read above.

   --------------------------------------------------------------------------

    4.23. Should I continue to use a "HOSTS" file for ad-blocking?

   One time-tested technique to defeat common ads is to trick the local DNS
   system by giving a phony IP address for the ad generator in the local
   HOSTS file, typically using 127.0.0.1, aka localhost. This effectively
   blocks the ad.

   There is no reason to use this technique in conjunction with Privoxy.
   Privoxy does essentially the same thing, much more elegantly and with much
   more flexibility. A large HOSTS file, in fact, not only duplicates effort,
   but may get in the way and seriously slow down your system. It is
   recommended to remove such entries from your HOSTS file. If you think your
   hosts list is neglected by Privoxy's configuration, consider adding your
   list to your user.action file:

     { +block }
      www.ad.example1.com
      ad.example2.com
      ads.galore.example.com
      etc.example.com

   --------------------------------------------------------------------------

    4.24. Where can I find more information about Privoxy and related issues?

   Other references and sites of interest to Privoxy users:

   http://www.privoxy.org/, the Privoxy Home page.

   http://www.privoxy.org/faq/, the Privoxy FAQ.

   http://sourceforge.net/projects/ijbswa/, the Project Page for Privoxy on
   SourceForge.

   http://config.privoxy.org/, the web-based user interface. Privoxy must be
   running for this to work. Shortcut: http://p.p/

   http://sourceforge.net/tracker/?group_id=11118&atid=460288, to submit
   "misses" and other configuration related suggestions to the developers.

   http://www.junkbusters.com/ht/en/cookies.html, an explanation how cookies
   are used to track web users.

   http://www.junkbusters.com/ijb.html, the original Internet Junkbuster.

   http://privacy.net/, a useful site to check what information about you is
   leaked while you browse the web.

   http://www.squid-cache.org/, a popular caching proxy, which is often used
   together with Privoxy.

   http://www.pps.jussieu.fr/~jch/software/polipo/, Polipo is a caching proxy
   with advanced features like pipelining, multiplexing and caching of
   partial instances. In many setups it can be used as Squid replacement.

   http://tor.eff.org/, Tor can help anonymize web browsing, web publishing,
   instant messaging, IRC, SSH, and other applications.

   http://www.privoxy.org/developer-manual/, the Privoxy developer manual.

   --------------------------------------------------------------------------

    4.25. I've noticed that Privoxy changes "Microsoft" to "MicroSuck"! Why are
    you manipulating my browsing?

   We're not. The text substitutions that you are seeing are disabled in the
   default configuration as shipped. You have either manually activated the
   "fun" filter which is clearly labeled "Text replacements for subversive
   browsing fun!" or you are using an older Privoxy version and have
   implicitly activated it by choosing the "Adventuresome" profile in the
   web-based editor. Please upgrade.

   --------------------------------------------------------------------------

    4.26. Does Privoxy produce "valid" HTML (or XHTML)?

   Privoxy generates HTML in both its own "templates", and possibly whenever
   there are text substitutions via a Privoxy filter. While this should
   always conform to the HTML 4.01 specifications, it has not been validated
   against this or any other standard.

   --------------------------------------------------------------------------

5. Troubleshooting

    5.1. I cannot connect to any websites. Or, I am getting "connection refused"
    message with every web page. Why?

   There are several possibilities:

     * Privoxy is not running. Solution: verify that Privoxy is installed
       correctly, has not crashed, and is indeed running. Turn on Privoxy's
       logging, and look at the logs to see what they say.

     * Or your browser is configured for a different port than what Privoxy
       is using. Solution: verify that Privoxy and your browser are set to
       the same port (listen-address).

     * Or if using a forwarding rule, you have a configuration problem or a
       problem with a host in the forwarding chain. Solution: temporarily
       alter your configuration and take the forwarders out of the equation.

     * Or you have a firewall that is interfering and blocking you. Solution:
       try disabling or removing the firewall as a simple test.

   --------------------------------------------------------------------------

    5.2. Why am I getting a 503 Error (WSAECONNREFUSED) on every page?

   More than likely this is a problem with your TCP/IP networking. ZoneAlarm
   has been reported to cause this symptom -- even if not running! The
   solution is to either fight the ZA configuration, or uninstall ZoneAlarm,
   and then find something better behaved in its place. Other personal
   firewall type products may cause similar type problems if not configured
   correctly.

   --------------------------------------------------------------------------

    5.3. I just added a new rule, but the steenkin ad is still getting through.
    How?

   If the ad had been displayed before you added its URL, it will probably be
   held in the browser's cache for some time, so it will be displayed without
   the need for any request to the server, and Privoxy will not be involved.
   Flush the browser's caches, and then try again.

   If this doesn't help, you probably have an error in the rule you applied.
   Try pasting the full URL of the offending ad into
   http://config.privoxy.org/show-url-info and see if it really matches your
   new rule. Blocking ads is like blocking spam: a lot of tinkering is
   required to stay ahead of the game. And remember you need to block the URL
   of the ad in question, which may be entirely different from the site URL
   itself. Most ads are hosted on different servers than the main site
   itself. If you right-click on the ad, you should be able to get all the
   relevant information you need. Alternately, you can find the correct URL
   by looking at Privoxy's logs (you may need to enable logging in the main
   config file if its disabled).

   Below is a slightly modified real-life log snippet that originates with
   one requested URL: www.example.com (name of site was changed for this
   example, the number of requests is real). You can see in this the
   complexity of what goes into making up this one "page". There are eight
   different domains involved here, with thirty two separate URLs requested
   in all, making up all manner of images, Shockwave Flash, JavaScript, CSS
   stylesheets, scripts, and other related content. Some of this content is
   obviously "good" or "bad", but not all. Many of the more questionable
   looking requests, are going to outside domains that seem to be identifying
   themselves with suspicious looking names, making our job a little easier.
   Privoxy has "crunched" (meaning caught and BLOCKED) quite a few items in
   this example, but perhaps missed a few as well.

Request: www.example.com/
Request: www.example.com/favicon.ico
Request: img.example.com/main.css
Request: img.example.com/sr.js
Request: example.betamarker.com/example.html
Request: www.lik-sang.com/Banners/bestsellers/skyscraper.php?likref=BSellers
Request: img.example.com/pb.png
Request: www.google-analytics.com/urchin.js crunch! (Blocked)
Request: www.advertising-department.com/ats/switch.ps.php?26856 crunch! (Blocked)
Request: img.example.com/p.gif
Request: www.popuptraffic.com/assign.php?l=example&mode=behind crunch! (Blocked)
Request: www.popuptraffic.com/scripts/popup.php?hid=5c3cf&tmpl=PBa.tmpl crunch! (Blocked)
Request: www.popuptraffic.com/assign.php?l=example crunch! (Blocked)
Request: www.lik-sang.com/Banners/best_sellers/best_sellers.css
Request: www.adtrak.net/adx.js crunch! (Blocked)
Request: img.example.com/hbg.gif
Request: img.example.com/example.jpg
Request: img.example.com/mt.png
Request: img.example.com/mm.png
Request: img.example.com/mb.png
Request: www.popuptraffic.com/scripts/popup.php?hid=a71b91fa5&tmpl=Ua.tmp crunch! (Blocked)
Request: www.example.com/tracker.js
Request: www.lik-sang.com/Banners/best_sellers/lsi_head.gif
Request: www.adtrak.net/adjs.php?n=020548130&what=zone:61 crunch! (Blocked)
Request: www.adtrak.net/adjs.php?n=463594413&what=zone:58&source=Ua crunch! (Blocked)
Request: www.lik-sang.com/Banners/best_sellers/bottomani.swf
Request: mmm.elitemediagroup.net/install.php?allowpop=no&popupmincook=0&allowsp2=1 crunch! (Blocked)
Request: www.example.com/tracker.js?screen=1400x1050&win=962x693
Request: www.adtrak.net/adlog.php?bannerid=1309&clientid=439&zoneid=61 crunch! (Blocked)
Request: 66.70.21.80/scripts/click.php?hid=5c3cf599a9efd0320d26&si
Request: 66.70.21.80/img/pixel.gif
Request: www.adtrak.net/adlog.php?bannerid=1309&clientid=439&zoneid=58&source=Ua&block=86400 crunch! (Blocked)
Request: 66.70.21.80/scripts/click.php?hid=a71b9f6504b0c5681fa5&si=Ua

   Despite 12 out of 32 requests being blocked, the page looked, and seemed
   to behave perfectly "normal" (minus some ads, of course).

   --------------------------------------------------------------------------

    5.4. One of my favorite sites does not work with Privoxy. What can I do?

   First verify that it is indeed a Privoxy problem, by toggling off Privoxy
   through http://config.privoxy.org/toggle (the toggle feature may need to
   be enabled in the main config), and then shift-reloading the problem page
   (i.e. holding down the shift key while clicking reload. Alternatively,
   flush your browser's disk and memory caches).

   If the problem went away, we know we have a configuration related problem.
   Now go to http://config.privoxy.org/show-url-info and paste the full URL
   of the page in question into the prompt. See which actions are being
   applied to the URL, and which matches in which actions files are
   responsible for that. It might be helpful also to look at your logs for
   this site too, to see what else might be happening (note: logging may need
   to be enabled in the main config file). Many sites are complex and require
   a number of related pages to help present their content. Look at what else
   might be used by the page in question, and what of that might be required.
   Now, armed with this information, go to
   http://config.privoxy.org/show-status and select the appropriate actions
   files for editing.

   You can now either look for a section which disables the actions that you
   suspect to cause the problem and add a pattern for your site there, or
   make up a completely new section for your site. In any case, the
   recommended way is to disable only the prime suspect, reload the problem
   page, and only if the problem persists, disable more and more actions
   until you have identified the culprit. You may or may not want to turn the
   other actions on again. Remember to flush your browser's caches in between
   any such changes!

   Alternately, if you are comfortable with a text editor, you can accomplish
   the same thing by editing the appropriate actions file. Probably the
   easiest way to deal with such problems when editing by hand is to add your
   site to a { fragile } section in user.action, which is an alias that turns
   off most "dangerous" actions, but is also likely to turn off more actions
   then needed, and thus lower your privacy and protection more than
   necessary,

   Troubleshooting actions is discussed in more detail in the User Manual
   appendix, Troubleshooting: the Anatomy of an Action. There is also an
   actions tutorial with general configuration information and examples.

   As a last resort, you can always see if your browser has a setting that
   will bypass the proxy setting for selective sites. Modern browsers can do
   this.

   --------------------------------------------------------------------------

    5.5. After installing Privoxy, I have to log in every time I start IE. What
    gives?

   This is a quirk that effects the installation of Privoxy, in conjunction
   with Internet Explorer and Internet Connection Sharing on Windows 2000 and
   Windows XP. The symptoms may appear to be corrupted or invalid DUN
   settings, or passwords.

   When setting up an NT based Windows system with Privoxy you may find that
   things do not seem to be doing what you expect. When you set your system
   up you will probably have set up Internet Connection Sharing (ICS) with
   Dial up Networking (DUN) when logged in with administrator privileges. You
   will probably have made this DUN connection available to other accounts
   that you may have set-up on your system. E.g. Mum or Dad sets up the
   system and makes accounts suitably configured for the kids.

   When setting up Privoxy in this environment you will have to alter the
   proxy set-up of Internet Explorer (IE) for the specific DUN connection on
   which you wish to use Privoxy. When you do this the ICS DUN set-up becomes
   user specific. In this instance you will see no difference if you change
   the DUN connection under the account used to set-up the connection.
   However when you do this from another user you will notice that the DUN
   connection changes to make available to "Me only". You will also find that
   you have to store the password under each different user!

   The reason for this is that each user's set-up for IE is user specific.
   Each set-up DUN connection and each LAN connection in IE store the
   settings for each user individually. As such this enforces individual
   configurations rather than common ones. Hence the first time you use a DUN
   connection after re-booting your system it may not perform as you expect,
   and prompt you for the password. Just set and save the password again and
   all should be OK.

   [Thanks to Ray Griffith for this submission.]

   --------------------------------------------------------------------------

    5.6. I cannot connect to any FTP sites. Privoxy is blocking me.

   Privoxy cannot act as a proxy for FTP traffic, so do not configure your
   browser to use Privoxy as an FTP proxy. The same is true for any protocol
   other than HTTP or HTTPS (SSL).

   Most browsers understand FTP as well as HTTP. If you connect to a site,
   with a URL like ftp://ftp.example.com, your browser is making an FTP
   connection, and not a HTTP connection. So while your browser may speak
   FTP, Privoxy does not, and cannot proxy such traffic.

   To complicate matters, some systems may have a generic "proxy" setting,
   which will enable various protocols, including both HTTP and FTP proxying!
   So it is possible to accidentally enable FTP proxying in these cases. And
   of course, if this happens, Privoxy will indeed cause problems since it
   does not know FTP. Newer version will give a sane error message if a FTP
   connection is attempted. Just disable the FTP setting and all will be well
   again.

   Will Privoxy ever proxy FTP traffic? Unlikely. There just is not much
   reason, and the work to make this happen is more than it may seem.

   --------------------------------------------------------------------------

    5.7. In Mac OSX, I can't configure Microsoft Internet Explorer to use
    Privoxy as the HTTP proxy.

   Microsoft Internet Explorer (in versions like 5.1) respects system-wide
   network settings. In order to change the HTTP proxy, open System
   Preferences, and click on the Network icon. In the settings pane that
   comes up, click on the Proxies tab. Ensure the "Web Proxy (HTTP)" checkbox
   is checked and enter 127.0.0.1 in the entry field. Enter 8118 in the Port
   field. The next time you start IE, it should reflect these values.

   --------------------------------------------------------------------------

    5.8. In Mac OSX, I dragged the Privoxy folder to the trash in order to
    uninstall it. Now the finder tells me I don't have sufficient privileges to
    empty the trash.

   Just dragging the Privoxy folder to the trash is not enough to delete it.
   Privoxy supplies an uninstall.command file that takes care of these
   details. Open the trash, drag the uninstall.command file out of the trash
   and double-click on it. You will be prompted for confirmation and the
   administration password.

   The trash may still appear full after this command; emptying the trash
   from the desktop should make it appear empty again.

   --------------------------------------------------------------------------

    5.9. In Mac OSX Panther (10.3), images often fail to load and/or I
    experience random delays in page loading. I'm using localhost as my
    browser's proxy setting.

   We believe this is due to an IPv6-related bug in OSX, but don't fully
   understand the issue yet. In any case, changing the proxy setting to
   127.0.0.1 instead of localhost works around the problem.

   --------------------------------------------------------------------------

    5.10. I get a completely blank page at one site. "View Source" shows only:
    <html><body></body></html>. Without Privoxy the page loads fine.

   Chances are that the site suffers from a bug in PHP, which results in
   empty pages being sent if the client explicitly requests an uncompressed
   page, like Privoxy does. This bug has been fixed in PHP 4.2.3.

   To find out if this is in fact the source of the problem, try adding the
   site to a -prevent-compression section in user.action:

   # Make exceptions for ill-behaved sites:
   #
   {-prevent-compression}
    .example.com

   If that works, you may also want to report the problem to the site's
   webmasters, telling them to use zlib.output_compression instead of
   ob_gzhandler in their PHP applications (workaround) or upgrade to PHP
   4.2.3 or later (fix).

   --------------------------------------------------------------------------

    5.11. My logs show many "Unable to get my own hostname" lines. Why?

   Privoxy tries to get the hostname of the system its running on from the IP
   address of the system interface it is bound to (from the config file
   listen-address setting). If the system cannot supply this information,
   Privoxy logs this condition.

   Typically, this would be considered a minor system configuration error. It
   is not a fatal error to Privoxy however, but may result in a much slower
   response from Privoxy on some platforms due to DNS timeouts.

   This can be caused by a problem with the local HOSTS file. If this file
   has been changed from the original, try reverting it to see if that helps.
   Make sure whatever name(s) are used for the local system, that they
   resolve both ways.

   --------------------------------------------------------------------------

    5.12. When I try to launch Privoxy, I get an error message "port 8118 is
    already in use" (or similar wording). Why?

   Port 8118 is Privoxy's default TCP "listening" port. Typically this
   message would mean that there is already one instance of Privoxy running,
   and your system is actually trying to start a second Privoxy on the same
   port, which will not work. (You can have multiple instances but they must
   be assigned different ports.) How and why this might happen varies from
   platform to platform, but you need to check your installation and start-up
   procedures.

   --------------------------------------------------------------------------

    5.13. Pages with UTF-8 fonts are garbled.

   This is caused by the "demoronizer" filter. You should either upgrade
   Privoxy, or at least upgrade to the most recent default.action file
   available from SourceForge. Or you can simply disable the demoronizer
   filter.

   --------------------------------------------------------------------------

    5.14. Why are binary files (such as images) corrupted when Privoxy is used?

   This may also be caused by the "demoronizer" filter, in conjunction with a
   web server that is misreporting the content type. Binary files are
   exempted from Privoxy's filtering (unless the web server by mistake says
   the file is something else). Either upgrade Privoxy, or go to the most
   recent default.action file available from SourceForge.

   --------------------------------------------------------------------------

    5.15. What is the "demoronizer" and why is it there?

   The original demoronizer was a Perl script that cleaned up HTML pages
   which were created with certain Microsoft products. MS has used
   proprietary extensions to standardized font encodings (ISO 8859-1), which
   has caused problems for pages that are viewed with non-Microsoft products
   (and are expecting to see a standard set of fonts). The demoronizer
   corrected these errors so the pages displayed correctly. Privoxy borrowed
   from this script, introducing a filter based on the original demoronizer,
   which in turn could correct these errors on the fly.

   But this is only needed in some situations, and will cause serious
   problems in some other situations.

   If you are using Microsoft products, you do not need it. If you need to
   view pages with UTF-8 characters (such as Cyrillic or Chinese), then it
   will cause corruption of the fonts, and thus should not be on.

   On the other hand, if you use non-Microsoft products, and you occasionally
   notice weird characters on pages, you might want to try it.

   --------------------------------------------------------------------------

    5.16. Why do I keep seeing "PrivoxyWindowOpen()" in raw source code?

   Privoxy is attempting to disable malicious Javascript in this case, with
   the unsolicited-popups filter. Privoxy cannot tell very well "good" code
   snippets from "bad" code snippets.

   If you see this in HTML source, and the page displays without problems,
   then this is good, and likely some pop-up window was disabled. If you see
   this where it is causing a problem, such as a downloaded program source
   code file, then you should set an exception for this site or page such
   that the integrity of the page stays in tact by disabling all filtering.

   --------------------------------------------------------------------------

    5.17. I am getting too many DNS errors like "404 No Such Domain". Why can't
    Privoxy do this better?

   There are potentially several factors here. First of all, the DNS
   resolution is done by the underlying operating system -- not Privoxy
   itself. Privoxy merely initiates the process and hands it off, and then
   later reports whatever the outcome was. And tries to give a coherent
   message if there seems to be a problem. In some cases, this might
   otherwise be mitigated by the browser itself which might try some
   work-arounds and alternate approaches (e.g adding "www." to the URL).

   In other cases, if Privoxy is being chained with another proxy, this could
   complicate the issue, and cause undue delays and timeouts. In the case of
   a "socks4a" proxy, the socks server handles all the DNS. Privoxy would
   just be the "messenger" which is reporting whatever problem occurred
   downstream, and not the root cause of the error.

   In any case, versions newer than 3.0.3 include various improvements to
   help Privoxy better handle these cases.

   --------------------------------------------------------------------------

    5.18. At one site Privoxy just hangs, and starts taking all CPU. Why is
    this?

   This is probably a manifestation of the "100% cpu" problem that occurs on
   pages containing many (thousands upon thousands) of blank lines. The blank
   lines are in the raw HTML source of the page, and the browser just ignores
   them. But the pattern matching in Privoxy's page filtering mechanism is
   trying to match against absurdly long strings and this becomes very
   CPU-intensive, taking a long, long time to complete. Until a better
   solution comes along, disable filtering on these pages, particularly the
   js-annoyances and unsolicited-popups filters.

   --------------------------------------------------------------------------

    5.19. I just installed Privoxy, and all my browsing has slowed to a crawl.
    What gives?

   This should not happen, and for the overwhelming number of users
   world-wide, it does not happen. I would suspect some inadvertent
   interaction of software components such as anti-virus software, spyware
   protectors, personal firewalls or similar components. Try disabling (or
   uninstalling) these one at a time and see if that helps.

   --------------------------------------------------------------------------

    5.20. Why do my filters work on some sites but not on others?

   It's probably due to compression. It is a common practice for web servers
   to send their content "compressed" in order to speed things up, and then
   let the browser "uncompress" them. When compiled with zlib support Privoxy
   can decompress content before filtering, otherwise you may want to enable
   prevent-compression.

   --------------------------------------------------------------------------

6. Contacting the developers, Bug Reporting and Feature Requests

   We value your feedback. In fact, we rely on it to improve Privoxy and its
   configuration. However, please note the following hints, so we can provide
   you with the best support:

   --------------------------------------------------------------------------

  6.1. Get Support

   For casual users, our support forum at SourceForge is probably best
   suited: http://sourceforge.net/tracker/?group_id=11118&atid=211118

   All users are of course welcome to discuss their issues on the users
   mailing list, where the developers also hang around.

   Note that the Privoxy mailing lists are moderated. Posts from unsubscribed
   addresses have to be accepted manually by a moderator. This may cause a
   delay of several days and if you use a subject that doesn't clearly
   mention Privoxy or one of its features, your message may be accidentally
   discarded as spam.

   If you aren't subscribed, you should therefore spend a few seconds to come
   up with a proper subject. Additionally you should make it clear that you
   want to get CC'd. Otherwise some responses will be directed to the mailing
   list only, and you won't see them.

   --------------------------------------------------------------------------

  6.2. Reporting Problems

   "Problems" for our purposes, come in two forms:

     * Configuration issues, such as ads that slip through, or sites that
       don't function properly due to one Privoxy "action" or another being
       turned "on".

     * "Bugs" in the programming code that makes up Privoxy, such as that
       might cause a crash.

   --------------------------------------------------------------------------

    6.2.1. Reporting Ads or Other Configuration Problems

   Please send feedback on ads that slipped through, innocent images that
   were blocked, sites that don't work properly, and other configuration
   related problem of default.action file, to
   http://sourceforge.net/tracker/?group_id=11118&atid=460288, the Actions
   File Tracker.

   New, improved default.action files may occasionally be made available
   based on your feedback. These will be announced on the ijbswa-announce
   list and available from our the files section of our project page.

   --------------------------------------------------------------------------

    6.2.2. Reporting Bugs

   Please report all bugs through our bug tracker:
   http://sourceforge.net/tracker/?group_id=11118&atid=111118.

   Before doing so, please make sure that the bug has not already been
   submitted and observe the additional hints at the top of the submit form.
   If already submitted, please feel free to add any info to the original
   report that might help to solve the issue.

   Please try to verify that it is a Privoxy bug, and not a browser or site
   bug or documented behaviour that just happens to be different than what
   you expected. If unsure, try toggling off Privoxy, and see if the problem
   persists.

   If you are using your own custom configuration, please try the stock
   configs to see if the problem is configuration related. If you're having
   problems with a feature that is disabled by default, please ask around on
   the mailing list if others can reproduce the problem.

   If you aren't using the latest Privoxy version, the bug may have been
   found and fixed in the meantime. We would appreciate if you could take the
   time to upgrade to the latest version (or even the latest CVS snapshot)
   and verify that your bug still exists.

   Please be sure to provide the following information:

     * The exact Privoxy version you are using (if you got the source from
       CVS, please also provide the source code revisions as shown in
       http://config.privoxy.org/show-version).

     * The operating system and versions you run Privoxy on, (e.g. Windows XP
       SP2), if you are using a Unix flavor, sending the output of "uname -a"
       should do, in case of GNU/Linux, please also name the distribution.

     * The name, platform, and version of the browser you were using (e.g.
       Internet Explorer v5.5 for Mac).

     * The URL where the problem occurred, or some way for us to duplicate
       the problem (e.g. http://somesite.example.com/?somethingelse=123).

     * Whether your version of Privoxy is one supplied by the Privoxy
       developers via SourceForge, or if you got your copy somewhere else.

     * Whether you are using Privoxy in tandem with another proxy such as
       Tor. If so, please temporary disable the other proxy to see if the
       symptoms change.

     * Whether you are using a personal firewall product. If so, does Privoxy
       work without it?

     * Any other pertinent information to help identify the problem such as
       config or log file excerpts (yes, you should have log file entries for
       each action taken).

   You don't have to tell us your actual name when filing a problem report,
   but please use a nickname so we can differentiate between your messages
   and the ones entered by other "anonymous" users that may respond to your
   request if they have the same problem or already found a solution.

   Please also check the status of your request a few days after submitting
   it, as we may request additional information. If you use a SF id, you
   should automatically get a mail when someone responds to your request.

   The appendix of the Privoxy User Manual also has helpful information on
   understanding actions, and action debugging.

   --------------------------------------------------------------------------

  6.3. Request New Features

   You are welcome to submit ideas on new features or other proposals for
   improvement through our feature request tracker at
   http://sourceforge.net/tracker/?atid=361118&group_id=11118.

   --------------------------------------------------------------------------

  6.4. Other

   For any other issues, feel free to use the mailing lists. Technically
   interested users and people who wish to contribute to the project are also
   welcome on the developers list! You can find an overview of all
   Privoxy-related mailing lists, including list archives, at:
   http://sourceforge.net/mail/?group_id=11118.

   --------------------------------------------------------------------------

7. Privoxy Copyright, License and History

   Copyright (c) 2001-2008 by Privoxy Developers
   <ijbswa-developers@lists.sourceforge.net>

   Some source code is based on code Copyright (c) 1997 by Anonymous Coders
   and Junkbusters, Inc. and licensed under the GNU General Public License.

   Portions of this document are "borrowed" from the original Junkbuster (tm)
   FAQ, and modified as appropriate for Privoxy.

   --------------------------------------------------------------------------

  7.1. License

   Privoxy is free software; you can redistribute it and/or modify it under
   the terms of the GNU General Public License, version 2, as published by
   the Free Software Foundation.

   This program is distributed in the hope that it will be useful, but
   WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
   or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
   for more details, which is available from the Free Software Foundation,
   Inc, 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA

   You should have received a copy of the GNU General Public License along
   with this program; if not, write to the

    Free Software
    Foundation, Inc. 51 Franklin Street, Fifth Floor
    Boston, MA 02110-1301
    USA

   --------------------------------------------------------------------------

  7.2. History

   A long time ago, there was the Internet Junkbuster, by Anonymous Coders
   and Junkbusters Corporation. This saved many users a lot of pain in the
   early days of web advertising and user tracking.

   But the web, its protocols and standards, and with it, the techniques for
   forcing ads on users, give up autonomy over their browsing, and for
   tracking them, keeps evolving. Unfortunately, the Internet Junkbuster did
   not. Version 2.0.2, published in 1998, was (and is) the last official
   release available from Junkbusters Corporation. Fortunately, it had been
   released under the GNU GPL, which allowed further development by others.

   So Stefan Waldherr started maintaining an improved version of the
   software, to which eventually a number of people contributed patches. It
   could already replace banners with a transparent image, and had a first
   version of pop-up killing, but it was still very closely based on the
   original, with all its limitations, such as the lack of HTTP/1.1 support,
   flexible per-site configuration, or content modification. The last release
   from this effort was version 2.0.2-10, published in 2000.

   Then, some developers picked up the thread, and started turning the
   software inside out, upside down, and then reassembled it, adding many new
   features along the way.

   The result of this is Privoxy, whose first stable version, 3.0, was
   released August, 2002.
