+Notes:
+
+ The URLs for the built-in images are "http://config.privoxy.org/
+ send-banner?type=type", where type is either "blank" or "pattern".
+
+ There is a third (advanced) type, called "auto". It is NOT to be used in
+ set-image-blocker, but meant for use from filters. Auto will select the
+ type of image that would have applied to the referring page, had it been an
+ image.
+
+Example usage:
+
+ Built-in pattern:
+
+ +set-image-blocker{pattern}
+
+ Redirect to the BSD devil:
+
+ +set-image-blocker{http://www.freebsd.org/gifs/dae_up3.gif}
+
+ Redirect to the built-in pattern for better caching:
+
+ +set-image-blocker{http://config.privoxy.org/send-banner?type=pattern}
+
+-------------------------------------------------------------------------------
+
+8.5.21. Summary
+
+Note that many of these actions have the potential to cause a page to
+misbehave, possibly even not to display at all. There are many ways a site
+designer may choose to design his site, and what HTTP header content, and other
+criteria, he may depend on. There is no way to have hard and fast rules for all
+sites. See the Appendix for a brief example on troubleshooting actions.
+
+-------------------------------------------------------------------------------
+
+8.6. Aliases
+
+Custom "actions", known to Privoxy as "aliases", can be defined by combining
+other actions. These can in turn be invoked just like the built-in actions.
+Currently, an alias name can contain any character except space, tab, "=", "{"
+and "}", but we strongly recommend that you only use "a" to "z", "0" to "9",
+"+", and "-". Alias names are not case sensitive, and are not required to start
+with a "+" or "-" sign, since they are merely textually expanded.
+
+Aliases can be used throughout the actions file, but they must be defined in a
+special section at the top of the file! And there can only be one such section
+per actions file. Each actions file may have its own alias section, and the
+aliases defined in it are only visible within that file.
+
+There are two main reasons to use aliases: One is to save typing for frequently
+used combinations of actions, the other one is a gain in flexibility: If you
+decide once how you want to handle shops by defining an alias called "shop",
+you can later change your policy on shops in one place, and your changes will
+take effect everywhere in the actions file where the "shop" alias is used.
+Calling aliases by their purpose also makes your actions files more readable.
+
+Currently, there is one big drawback to using aliases, though: Privoxy's
+built-in web-based action file editor honors aliases when reading the actions
+files, but it expands them before writing. So the effects of your aliases are
+of course preserved, but the aliases themselves are lost when you edit sections
+that use aliases with it. This is likely to change in future versions of
+Privoxy.
+
+Now let's define some aliases...
+
+ # Useful custom aliases we can use later.
+ #
+ # Note the (required!) section header line and that this section
+ # must be at the top of the actions file!
+ #
+ {{alias}}
+
+ # These aliases just save typing later:
+ # (Note that some already use other aliases!)
+ #
+ +crunch-all-cookies = +crunch-incoming-cookies +crunch-outgoing-cookies
+ -crunch-all-cookies = -crunch-incoming-cookies -crunch-outgoing-cookies
+ block-as-image = +block +handle-as-image
+ mercy-for-cookies = -crunch-all-cookies -session-cookies-only
+
+ # These aliases define combinations of actions
+ # that are useful for certain types of sites:
+ #
+ fragile = -block -crunch-all-cookies -filter -fast-redirects -hide-referer -kill-popups
+ shop = -crunch-all-cookies -filter{popups} -kill-popups
+
+ # Short names for other aliases, for really lazy people ;-)
+ #
+ c0 = +crunch-all-cookies
+ c1 = -crunch-all-cookies
+
+...and put them to use. These sections would appear in the lower part of an
+actions file and define exceptions to the default actions (as specified further
+up for the "/" pattern):
+
+ # These sites are either very complex or very keen on
+ # user data and require minimal interference to work:
+ #
+ {fragile}
+ .office.microsoft.com
+ .windowsupdate.microsoft.com
+ .nytimes.com
+
+ # Shopping sites:
+ # Allow cookies (for setting and retrieving your customer data)
+ #
+ {shop}
+ .quietpc.com
+ .worldpay.com # for quietpc.com
+ .scan.co.uk
+
+ # These shops require pop-ups:
+ #
+ {shop -kill-popups -filter{popups}}
+ .dabs.com
+ .overclockers.co.uk
+
+Aliases like "shop" and "fragile" are often used for "problem" sites that
+require some actions to be disabled in order to function properly.
+
+-------------------------------------------------------------------------------
+
+8.7. Actions Files Tutorial
+
+The above chapters have shown which actions files there are and how they are
+organized, how actions are specified and applied to URLs, how patterns work,
+and how to define and use aliases. Now, let's look at an example default.action
+and user.action file and see how all these pieces come together:
+
+-------------------------------------------------------------------------------
+
+8.7.1. default.action
+
+Every config file should start with a short comment stating its purpose:
+
+# Sample default.action file <developers@privoxy.org>
+
+Then, since this is the default.action file, the first section is a special
+section for internal use that you needn't change or worry about:
+
+##########################################################################
+# Settings -- Don't change! For internal Privoxy use ONLY.
+##########################################################################
+
+{{settings}}
+for-privoxy-version=3.0
+
+After that comes the (optional) alias section. We'll use the example section
+from the above chapter on aliases, that also explains why and how aliases are
+used:
+
+##########################################################################
+# Aliases
+##########################################################################
+{{alias}}
+
+# These aliases just save typing later:
+# (Note that some already use other aliases!)
+#
++crunch-all-cookies = +crunch-incoming-cookies +crunch-outgoing-cookies
+-crunch-all-cookies = -crunch-incoming-cookies -crunch-outgoing-cookies
+block-as-image = +block +handle-as-image
+mercy-for-cookies = -crunch-all-cookies -session-cookies-only
+
+# These aliases define combinations of actions
+# that are useful for certain types of sites:
+#
+fragile = -block -crunch-all-cookies -filter -fast-redirects -hide-referer -kill-popups
+shop = mercy-for-cookies -filter{popups} -kill-popups
+
+Now come the regular sections, i.e. sets of actions, accompanied by URL
+patterns to which they apply. Remember all actions are disabled when matching
+starts, so we have to explicitly enable the ones we want.
+
+The first regular section is probably the most important. It has only one
+pattern, "/", but this pattern matches all URLs. Therefore, the set of actions
+used in this "default" section will be applied to all requests as a start. It
+can be partly or wholly overridden by later matches further down this file, or
+in user.action, but it will still be largely responsible for your overall
+browsing experience.
+
+Again, at the start of matching, all actions are disabled, so there is no real
+need to disable any actions here, but we will do that nonetheless, to have a
+complete listing for your reference. (Remember: a "+" preceding the action name
+enables the action, a "-" disables!). Also note how this long line has been
+made more readable by splitting it into multiple lines with line continuation.
+
+##########################################################################
+# "Defaults" section:
+##########################################################################
+ { \
+ -add-header \
+ -block \
+ -crunch-incoming-cookies \
+ -crunch-outgoing-cookies \
+ +deanimate-gifs \
+ -downgrade-http-version \
+ +fast-redirects \
+ +filter{html-annoyances} \
+ +filter{js-annoyances} \
+ -filter{content-cookies} \
+ +filter{popups} \
+ +filter{webbugs} \
+ -filter{refresh-tags} \
+ -filter{fun} \
+ +filter{nimda} \
+ +filter{banners-by-size} \
+ -filter{banners-by-link} \
+ -filter{img-reorder} \
+ -filter{shockwave-flash} \
+ -filter{crude-parental} \
+ -filter{js-events} \
+ -handle-as-image \
+ +hide-forwarded-for-headers \
+ +hide-from-header{block} \
+ +hide-referrer{forge} \
+ -hide-user-agent \
+ -kill-popups \
+ -limit-connect \
+ +prevent-compression \
+ -send-vanilla-wafer \
+ -send-wafer \
+ +session-cookies-only \
+ +set-image-blocker{pattern} \
+ }
+ / # forward slash will match *all* potential URL patterns.
+
+The default behavior is now set. Note that some actions, like not hiding the
+user agent, are part of a "general policy" that applies universally and won't
+get any exceptions defined later. Other choices, like not blocking (which is
+understandably the default!) need exceptions, i.e. we need to specify
+explicitly what we want to block in later sections. We will also want to make
+exceptions from our general pop-up-killing, and use our defined aliases for
+that.
+
+The first of our specialized sections is concerned with "fragile" sites, i.e.
+sites that require minimum interference, because they are either very complex
+or very keen on tracking you (and have mechanisms in place that make them
+unusable for people who avoid being tracked). We will simply use our
+pre-defined fragile alias instead of stating the list of actions explicitly:
+
+##########################################################################
+# Exceptions for sites that'll break under the default action set:
+##########################################################################
+
+# "Fragile" Use a minimum set of actions for these sites (see alias above):
+#
+{ fragile }
+.office.microsoft.com # surprise, surprise!
+.windowsupdate.microsoft.com
+
+Shopping sites are not as fragile, but they typically require cookies to log
+in, and pop-up windows for shopping carts or item details. Again, we'll use a
+pre-defined alias:
+
+# Shopping sites:
+#
+{ shop }
+.quietpc.com
+.worldpay.com # for quietpc.com
+.jungle.com
+.scan.co.uk
+
+Then, there are sites which rely on pop-up windows (yuck!) to work. Since we
+made pop-up-killing our default above, we need to make exceptions now. Mozilla
+users, who can turn on smart handling of unwanted pop-ups in their browsers,
+can safely choose -filter{popups} (and -kill-popups) above and hence don't need
+this section. Anyway, disabling an already disabled action doesn't hurt, so
+we'll define our exceptions regardless of what was chosen in the defaults
+section:
+
+# These sites require pop-ups too :(
+#
+{ -kill-popups -filter{popups} }
+.dabs.com
+.overclockers.co.uk
+.deutsche-bank-24.de
+
+The fast-redirects action, which we enabled per default above, breaks some
+sites. So disable it for popular sites where we know it misbehaves:
+
+{ -fast-redirects }
+login.yahoo.com
+edit.*.yahoo.com
+.google.com
+.altavista.com/.*(like|url|link):http
+.altavista.com/trans.*urltext=http
+.nytimes.com
+
+It is important that Privoxy knows which URLs belong to images, so that if they
+are to be blocked, a substitute image can be sent, rather than an HTML page.
+Contacting the remote site to find out is not an option, since it would destroy
+the loading time advantage of banner blocking, and it would feed the
+advertisers (in terms of money and information). We can mark any URL as an
+image with the handle-as-image action, and marking all URLs that end in a known
+image file extension is a good start:
+
+##########################################################################
+# Images:
+##########################################################################
+
+# Define which file types will be treated as images, in case they get
+# blocked further down this file:
+#
+{ +handle-as-image }
+/.*\.(gif|jpe?g|png|bmp|ico)$
+
+And then there are known banner sources. They often use scripts to generate the
+banners, so it won't be visible from the URL that the request is for an image.
+Hence we block them and mark them as images in one go, with the help of our
+block-as-image alias defined above. (We could of course just as well use +block
++handle-as-image here.) Remember that the type of the replacement image is
+chosen by the set-image-blocker action. Since all URLs have matched the default
+section with its +set-image-blocker{pattern} action before, it still applies
+and needn't be repeated:
+
+# Known ad generators:
+#
+{ block-as-image }
+ar.atwola.com
+.ad.doubleclick.net
+.ad.*.doubleclick.net
+.a.yimg.com/(?:(?!/i/).)*$
+.a[0-9].yimg.com/(?:(?!/i/).)*$
+bs*.gsanet.com
+bs*.einets.com
+.qkimg.net
+
+One of the most important jobs of Privoxy is to block banners. A huge bunch of
+them are already "blocked" by the filter{banners-by-size} action, which we
+enabled above, and which deletes the references to banner images from the pages
+while they are loaded, so the browser doesn't request them anymore, and hence
+they don't need to be blocked here. But this naturally doesn't catch all
+banners, and some people choose not to use filters, so we need a comprehensive
+list of patterns for banner URLs here, and apply the block action to them.
+
+First comes a bunch of generic patterns, which do most of the work, by matching
+typical domain and path name components of banners. Then comes a list of
+individual patterns for specific sites, which is omitted here to keep the
+example short:
+
+##########################################################################
+# Block these fine banners:
+##########################################################################
+{ +block }
+
+# Generic patterns:
+#
+ad*.
+.*ads.
+banner?.
+count*.
+/.*count(er)?\.(pl|cgi|exe|dll|asp|php[34]?)
+/(?:.*/)?(publicite|werbung|rekla(ma|me|am)|annonse|maino(kset|nta|s)?)/
+
+# Site-specific patterns (abbreviated):
+#
+.hitbox.com
+
+You wouldn't believe how many advertisers actually call their banner servers
+ads.company.com, or call the directory in which the banners are stored simply
+"banners". So the above generic patterns are surprisingly effective.
+
+But being very generic, they necessarily also catch URLs that we don't want to
+block. The pattern .*ads. e.g. catches "nasty-ads.nasty-corp.com" as intended,
+but also "downloads.sourcefroge.net" or "adsl.some-provider.net." So here come
+some well-known exceptions to the +block section above.
+
+Note that these are exceptions to exceptions from the default! Consider the URL
+"downloads.sourcefroge.net": Initially, all actions are deactivated, so it
+wouldn't get blocked. Then comes the defaults section, which matches the URL,
+but just deactivates the block action once again. Then it matches .*ads., an
+exception to the general non-blocking policy, and suddenly +block applies. And
+now, it'll match .*loads., where -block applies, so (unless it matches again
+further down) it ends up with no block action applying.
+
+##########################################################################
+# Save some innocent victims of the above generic block patterns:
+##########################################################################
+
+# By domain:
+#
+{ -block }
+adv[io]*. # (for advogato.org and advice.*)
+adsl. # (has nothing to do with ads)
+ad[ud]*. # (adult.* and add.*)
+.edu # (universities don't host banners (yet!))
+.*loads. # (downloads, uploads etc)
+
+# By path:
+#
+/.*loads/
+
+# Site-specific:
+#
+www.globalintersec.com/adv # (adv = advanced)
+www.ugu.com/sui/ugu/adv
+
+Filtering source code can have nasty side effects, so make an exception for our
+friends at sourceforge.net, and all paths with "cvs" in them. Note that -filter
+disables all filters in one fell swoop!
+
+# Don't filter code!
+#
+{ -filter }
+/.*cvs
+.sourceforge.net
+
+The actual default.action is of course more comprehensive, but we hope this
+example made clear how it works.
+
+-------------------------------------------------------------------------------
+
+8.7.2. user.action
+
+So far we are painting with a broad brush by setting general policies, which
+would be a reasonable starting point for many people. Now, you might want to be
+more specific and have customized rules that are more suitable to your personal
+habits and preferences. These would be for narrowly defined situations like
+your ISP or your bank, and should be placed in user.action, which is parsed
+after all other actions files and hence has the last word, over-riding any
+previously defined actions. user.action is also a safe place for your personal
+settings, since default.action is actively maintained by the Privoxy developers
+and you'll probably want to install updated versions from time to time.
+
+So let's look at a few examples of things that one might typically do in
+user.action:
+
+# My user.action file. <fred@foobar.com>
+
+As aliases are local to the actions file that they are defined in, you can't
+use the ones from default.action, unless you repeat them here:
+
+# (Re-)define aliases for this file:
+#
+{{alias}}
+-crunch-all-cookies = -crunch-incoming-cookies -crunch-outgoing-cookies
+mercy-for-cookies = -crunch-all-cookies -session-cookies-only
+fragile = -block -crunch-all-cookies -filter -fast-redirects -hide-referer -kill-popups
+shop = mercy-for-cookies -filter{popups} -kill-popups
+allow-ads = -block -filter{banners-by-size} # (see below)
+
+Say you have accounts on some sites that you visit regularly, and you don't
+want to have to log in manually each time. So you'd like to allow persistent
+cookies for these sites. The mercy-for-cookies alias defined above does exactly
+that, i.e. it disables crunching of cookies in any direction, and processing of
+cookies to make them temporary.
+
+{ mercy-for-cookies }
+sunsolve.sun.com
+slashdot.org
+.yahoo.com
+.msdn.microsoft.com
+.redhat.com
+
+Your bank needs popups and is allergic to some filter, but you don't know
+which, so you disable them all:
+
+{ -filter -kill-popups }
+.your-home-banking-site.com
+
+While browsing the web with Privoxy you noticed some ads that sneaked through,
+but you were too lazy to report them through our fine and easy feedback system,
+so you have added them here:
+
+{ +block }
+www.a-popular-site.com/some/unobvious/path
+another.popular.site.net/more/junk/here/
+
+Note that, assuming the banners in the above example have regular image
+extensions (most do), +handle-as-image need not be specified, since all URLs
+ending in these extensions will already have been tagged as images in the
+relevant section of default.action by now.
+
+Then you noticed that the default configuration breaks Forbes Magazine, but you
+were too lazy to find out which action is the culprit, and you were again too
+lazy to give feedback, so you just used the fragile alias on the site, and --
+whoa! -- it worked:
+
+{ fragile }
+.forbes.com
+
+You like the "fun" text replacements in default.filter, but it is disabled in
+the distributed actions file. (My colleagues on the team just don't have a
+sense of humour, that's why! ;-). So you'd like to turn it on in your private,
+update-safe config, once and for all:
+
+{ +filter{fun} }
+/ # For ALL sites!
+
+Note that the above is not really a good idea: There are exceptions to the
+filters in default.action for things that really shouldn't be filtered, like
+code on CVS->Web interfaces. Since user.action has the last word, these
+exceptions won't be valid for the "fun" filtering specified here.
+
+Finally, you might think about how your favourite free websites are funded, and
+find that they rely on displaying banner advertisements to survive. So you
+might want to specifically allow banners for those sites that you feel provide
+value to you:
+
+{ allow-ads }
+.sourceforge.net
+.slashdot.org
+.osdn.net
+
+Note that allow-ads has been aliased to -block -filter{banners-by-size} above.
+
+-------------------------------------------------------------------------------
+
+9. The Filter File
+
+All text substitutions that can be invoked through the filter action must first
+be defined in the filter file, which is typically called default.filter and
+which can be selected through the filterfile config option.
+
+Typical reasons for doing such substitutions are to eliminate common annoyances
+in HTML and JavaScript, such as pop-up windows, exit consoles, crippled windows
+without navigation tools, the infamous <BLINK> tag etc, to suppress images with
+certain width and height attributes (standard banner sizes or web-bugs), or
+just to have fun. The possibilities are endless.
+
+Filtering works on any text-based document type, including plain text, HTML,
+JavaScript, CSS etc. (all text/* MIME types). Substitutions are made at the
+source level, so if you want to "roll your own" filters, you should be familiar
+with HTML syntax.
+
+Just like the actions files, the filter file is organized in sections, which
+are called filters here. Each filter consists of a heading line, that starts
+with the keyword FILTER:, followed by the filter's name, and a short (one line)
+description of what it does. Below that line come the jobs, i.e. lines that
+define the actual text substitutions. By convention, the name of a filter
+should describe what the filter eliminates. The comment is used in the
+web-based user interface.
+
+Once a filter called name has been defined in the filter file, it can be
+invoked by using an action of the form +filter{name} in any actions file.
+
+A filter header line for a filter called "foo" could look like this:
+
+FILTER: foo Replace all "foo" with "bar"
+
+Below that line, and up to the next header line, come the jobs that define what
+text replacements the filter executes. They are specified in a syntax that
+imitates Perl's s/// operator. If you are familiar with Perl, you will find
+this to be quite intuitive, and may want to look at the PCRS man page for the
+subtle differences to Perl behaviour. Most notably, the non-standard option
+letter U is supported, which turns the default to ungreedy matching.
+
+If you are new to regular expressions, you might want to take a look at the
+Appendix on regular expressions, and see the Perl manual for the s///
+operator's syntax and Perl-style regular expressions in general. The below
+examples might also help to get you started.
+
+-------------------------------------------------------------------------------
+
+9.1. Filter File Tutorial
+
+Now, let's complete our "foo" filter. We have already defined the heading, but
+the jobs are still missing. Since all it does is to replace "foo" with "bar",
+there is only one (trivial) job needed:
+
+s/foo/bar/
+
+But wait! Didn't the comment say that all occurrences of "foo" should be
+replaced? Our current job will only take care of the first "foo" on each page.
+For global substitution, we'll need to add the g option:
+
+s/foo/bar/g
+
+Our complete filter now looks like this:
+
+FILTER: foo Replace all "foo" with "bar"
+s/foo/bar/g
+
+Let's look at some real filters for more interesting examples. Here you see a
+filter that protects against some common annoyances that arise from JavaScript
+abuse. Let's look at its jobs one after the other:
+
+FILTER: js-annoyances Get rid of particularly annoying JavaScript abuse
+
+# Get rid of JavaScript referrer tracking. Test page: http://www.randomoddness.com/untitled.htm
+#
+s|(<script.*)document\.referrer(.*</script>)|$1"Not Your Business!"$2|Usg
+
+Following the header line and a comment, you see the job. Note that it uses |
+as the delimiter instead of /, because the pattern contains a forward slash,
+which would otherwise have to be escaped by a backslash (\).
+
+Now, let's examine the pattern: it starts with the text <script.* enclosed in
+parentheses. Since the dot matches any character, and * means: "Match an
+arbitrary number of the element left of myself", this matches "<script",
+followed by any text, i.e. it matches the whole page, from the start of the
+first <script> tag.
+
+That's more than we want, but the pattern continues: document\.referrer matches
+only the exact string "document.referrer". The dot needed to be escaped, i.e.
+preceded by a backslash, to take away its special meaning as a joker, and make
+it just a regular dot. So far, the meaning is: Match from the start of the
+first <script> tag in a the page, up to, and including, the text
+"document.referrer", if both are present in the page (and appear in that
+order).
+
+But there's still more pattern to go. The next element, again enclosed in
+parentheses, is .*</script>. You already know what .* means, so the whole
+pattern translates to: Match from the start of the first <script> tag in a page
+to the end of the last <script> tag, provided that the text "document.referrer"
+appears somewhere in between.
+
+This is still not the whole story, since we have ignored the options and the
+parentheses: The portions of the page matched by sub-patterns that are enclosed
+in parentheses, will be remembered and be available through the variables $1,
+$2, ... in the substitute. The U option switches to ungreedy matching, which
+means that the first .* in the pattern will only "eat up" all text in between "
+<script" and the first occurrence of "document.referrer", and that the second .
+* will only span the text up to the first "</script>" tag. Furthermore, the s
+option says that the match may span multiple lines in the page, and the g
+option again means that the substitution is global.
+
+So, to summarize, the pattern means: Match all scripts that contain the text
+"document.referrer". Remember the parts of the script from (and including) the
+start tag up to (and excluding) the string "document.referrer" as $1, and the
+part following that string, up to and including the closing tag, as $2.
+
+Now the pattern is deciphered, but wasn't this about substituting things? So
+lets look at the substitute: $1"Not Your Business!"$2 is easy to read: The text
+remembered as $1, followed by "Not Your Business!" (including the quotation
+marks!), followed by the text remembered as $2. This produces an exact copy of
+the original string, with the middle part (the "document.referrer") replaced by
+"Not Your Business!".
+
+The whole job now reads: Replace "document.referrer" by "Not Your Business!"
+wherever it appears inside a <script> tag. Note that this job won't break
+JavaScript syntax, since both the original and the replacement are
+syntactically valid string objects. The script just won't have access to the
+referrer information anymore.
+
+We'll show you two other jobs from the JavaScript taming department, but this
+time only point out the constructs of special interest:
+
+# The status bar is for displaying link targets, not pointless blahblah
+#
+s/window\.status\s*=\s*(['"]).*?\1/dUmMy=1/ig
+
+\s stands for whitespace characters (space, tab, newline, carriage return, form
+feed), so that \s* means: "zero or more whitespace". The ? in .*? makes this
+matching of arbitrary text ungreedy. (Note that the U option is not set). The
+['"] construct means: "a single or a double quote". Finally, \1 is a
+backreference to the first parenthesis just like $1 above, with the difference
+that in the pattern, a backslash indicates a backreference, whereas in the
+substitute, it's the dollar.
+
+So what does this job do? It replaces assignments of single- or double-quoted
+strings to the "window.status" object with a dummy assignment (using a variable
+name that is hopefully odd enough not to conflict with real variables in
+scripts). Thus, it catches many cases where e.g. pointless descriptions are
+displayed in the status bar instead of the link target when you move your mouse
+over links.
+
+# Kill OnUnload popups. Yummy. Test: http://www.zdnet.com/zdsubs/yahoo/tree/yfs.html
+#
+s/(<body [^>]*)onunload(.*>)/$1never$2/iU
+
+Including the OnUnload event binding in the HTML DOM was a CRIME. When I close
+a browser window, I want it to close and die. Basta. This job replaces the
+"onunload" attribute in "<body>" tags with the dummy word never. Note that the
+i option makes the pattern matching case-insensitive. Also note that ungreedy
+matching alone doesn't always guarantee a minimal match: In the first
+parenthesis, we had to use [^>]* instead of .* to prevent the match from
+exceeding the <body> tag if it doesn't contain "OnUnload", but the page's
+content does.
+
+The last example is from the fun department:
+
+FILTER: fun Fun text replacements
+
+# Spice the daily news:
+#
+s/microsoft(?!\.com)/MicroSuck/ig
+
+Note the (?!\.com) part (a so-called negative lookahead) in the job's pattern,
+which means: Don't match, if the string ".com" appears directly following
+"microsoft" in the page. This prevents links to microsoft.com from being
+trashed, while still replacing the word everywhere else.
+
+# Buzzword Bingo (example for extended regex syntax)
+#
+s* industry[ -]leading \
+| cutting[ -]edge \
+| customer[ -]focused \
+| market[ -]driven \
+| award[ -]winning # Comments are OK, too! \
+| high[ -]performance \
+| solutions[ -]based \
+| unmatched \
+| unparalleled \
+| unrivalled \
+*<font color="red"><b>BINGO!</b></font> \
+*igx
+
+The x option in this job turns on extended syntax, and allows for e.g. the
+liberal use of (non-interpreted!) whitespace for nicer formatting.
+
+You get the idea?
+
+-------------------------------------------------------------------------------
+
+10. Templates
+
+All Privoxy built-in pages, i.e. error pages such as the "404 - No Such Domain"
+error page, the "BLOCKED" page and all pages of its web-based user interface,
+are generated from templates. (Privoxy must be running for the above links to
+work as intended.)
+
+These templates are stored in a subdirectory of the configuration directory
+called templates. On Unixish platforms, this is typically /etc/privoxy/
+templates/.
+
+The templates are basically normal HTML files, but with place-holders (called
+symbols or exports), which Privoxy fills at run time. You can edit the
+templates with a normal text editor, should you want to customize them. (Not
+recommended for the casual user). Note that just like in configuration files,
+lines starting with # are ignored when the templates are filled in.
+
+The place-holders are of the form @name@, and you will find a list of available
+symbols, which vary from template to template, in the comments at the start of
+each file. Note that these comments are not always accurate, and that it's
+probably best to look at the existing HTML code to find out which symbols are
+supported and what they are filled in with.
+
+A special application of this substitution mechanism is to make whole blocks of
+HTML code disappear when a specific symbol is set. We use this for many
+purposes, one of them being to include the beta warning in all our user
+interface (CGI) pages when Privoxy in in an alpha or beta development stage:
+
+<!-- @if-unstable-start -->
+
+ ... beta warning HTML code goes here ...
+
+<!-- if-unstable-end@ -->
+
+If the "unstable" symbol is set, everything in between and including
+@if-unstable-start and if-unstable-end@ will disappear, leaving nothing but an
+empty comment:
+
+<!-- -->
+
+There's also an if-then-else construct and an #include mechanism, but you'll
+sure find out if you are inclined to edit the templates ;-)
+
+All templates refer to a style located at http://config.privoxy.org/
+send-stylesheet. This is, of course, locally served by Privoxy and the source
+for it can be found and edited in the cgi-style.css template.
+
+-------------------------------------------------------------------------------
+
+11. Contacting the Developers, Bug Reporting and Feature Requests
+
+We value your feedback. In fact, we rely on it to improve Privoxy and its
+configuration. However, please note the following hints, so we can provide you
+with the best support:
+
+-------------------------------------------------------------------------------
+
+11.1. Get Support
+
+For casual users, our support forum at SourceForge is probably best suited:
+http://sourceforge.net/tracker/?group_id=11118&atid=211118
+
+All users are of course welcome to discuss their issues on the users mailing
+list, where the developers also hang around.
+
+-------------------------------------------------------------------------------
+
+11.2. Report Bugs
+
+Please report all bugs only 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.
+
+Please try to verify that it is a Privoxy bug, and not a browser or site bug
+first. If unsure, try toggling off Privoxy, and see if the problem persists.
+The appendix of the user manual also has helpful information on action
+debugging. If you are using your own custom configuration, please try the stock
+configs to see if the problem is configuration related.
+
+If not using the latest version, chances are that the bug has 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 your
+bug, but this is not required for reporting.
+
+-------------------------------------------------------------------------------
+
+11.3. Request New Features
+
+You are welcome to submit ideas on new features or other proposals for
+improvement through our feature request tracker at http://sourceforge.net/
+tracker/?atid=361118&group_id=11118.
+
+-------------------------------------------------------------------------------
+
+11.4. Report Ads or Other Actions-Related Problems
+
+Please send feedback on ads that slipped through, innocent images that were
+blocked, and any other problems relating to the default.action file through our
+actions feedback mechanism located at http://www.privoxy.org/actions/. On this
+page, you will also find a bookmark which will take you back there from any
+troubled site and even pre-fill the form!
+
+New, improved default.action files will occasionally be made available based on
+your feedback. These will be announced on the ijbswa-announce list and
+available from our the files section of our project page.
+
+-------------------------------------------------------------------------------
+
+11.5. Other
+
+For any other issues, feel free to use the mailing lists. Technically
+interested users and people who wish to contribute to the project are also
+welcome on the developers list! You can find an overview of all Privoxy-related
+mailing lists, including list archives, at: http://sourceforge.net/mail/?
+group_id=11118.
+
+-------------------------------------------------------------------------------
+
+12. Privoxy Copyright, License and History
+
+Copyright © 2001, 2002 by Privoxy Developers <developers@privoxy.org>
+
+Some source code is based on code Copyright © 1997 by Anonymous Coders and
+Junkbusters, Inc. and licensed under the GNU General Public License.
+
+-------------------------------------------------------------------------------
+
+12.1. License
+
+Privoxy is free software; you can redistribute it and/or modify it under the
+terms of the GNU General Public License, version 2, as published by the Free
+Software Foundation.
+
+This program is distributed in the hope that it will be useful, but WITHOUT ANY
+WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A
+PARTICULAR PURPOSE. See the GNU General Public License for more details, which
+is available from the Free Software Foundation, Inc, 59 Temple Place - Suite
+330, Boston, MA 02111-1307, 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. 59 Temple Place - Suite 330
+ Boston, MA 02111-1307
+ USA
+
+-------------------------------------------------------------------------------
+
+12.2. History
+
+In the beginning, there was the Internet Junkbuster, by Anonymous Coders and
+Junkbusters Corporation. It 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 users to consume ads, give up autonomy over their browsing, and for
+spying on them, kept 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 release, 3.0, was released
+August, 2002.
+
+-------------------------------------------------------------------------------
+
+12.3. Authors
+
+Current Project Developers:
+
+ Jon Foster
+ Andreas Oesterhelt
+ Stefan Waldherr
+
+ Thomas Steudten
+ Rodney Stromlund
+
+Current Project Contributors:
+
+ Rodrigo Barbosa (RPM specfiles)
+ Moritz Barsnick
+ Hal Burgiss (docs)
+ Karsten Hopp (Red Hat)
+ Alexander Lazic
+ Gábor Lipták
+ Guy
+ Haroon Rafique
+ Roland Rosenfeld (Debian)
+ Georg Sauthoff (Gentoo)
+ David Schmidt (OS/2, Mac OSX ports)
+ Joerg Strohmayer (Amiga)
+ Sarantis Paskalis
+
+Based in part on code originally developed by:
+
+ Junkbusters Corp.
+ Anonymous Coders
+
+Thanks to the many people who have tested Privoxy, reported bugs, or made
+suggestions. These include (in alphabetical order):
+
+ Ken Arromdee
+ Devin Bayer
+ Reiner Buehl
+ Andrew J. Caines
+ Clifford Caoile
+ Michael T. Davis
+ Peter E
+ Aaron Hamid
+ Magnus Holmgren
+ Daniel Leite
+ Paul Lieverse
+ David Mediavilla
+ Roberto Ragusa
+ Maynard Riley
+ Bart Schelstraete
+ Darren Wiebe
+ Jamie Zawinski
+
+-------------------------------------------------------------------------------
+
+13. See Also
+
+Other references and sites of interest to Privoxy users:
+
+http://www.privoxy.org/, the Privoxy Home page.
+
+http://www.privoxy.org/faq/, the Privoxy FAQ.
+
+http://sourceforge.net/projects/ijbswa/, the Project Page for Privoxy on
+SourceForge.
+
+http://config.privoxy.org/, the web-based user interface. Privoxy must be
+running for this to work. Shortcut: http://p.p/
+
+http://www.privoxy.org/actions/, to submit "misses" to the developers.
+
+http://cvs.sourceforge.net/cgi-bin/viewcvs.cgi/ijbswa/contrib/, cool and fun
+ideas from Privoxy users.
+
+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://www.waldherr.org/junkbuster/, Stefan Waldherr's version of Junkbuster,
+from which Privoxy was derived.
+
+http://privacy.net/analyze/, a useful site to check what information about you
+is leaked while you browse the web.
+
+http://www.squid-cache.org/, a very popular caching proxy, which is often used
+together with Privoxy.
+
+http://www.privoxy.org/developer-manual/, the Privoxy developer manual.
+
+-------------------------------------------------------------------------------
+
+14. Appendix
+
+14.1. Regular Expressions
+
+Privoxy uses Perl-style "regular expressions" in its actions files and filter
+file, through the PCRE and PCRS libraries.
+
+If you are reading this, you probably don't understand what "regular
+expressions" are, or what they can do. So this will be a very brief
+introduction only. A full explanation would require a book ;-)
+
+Regular expressions provide a language to describe patterns that can be run
+against strings of characters (letter, numbers, etc), to see if they match the
+string or not. The patterns are themselves (sometimes complex) strings of
+literal characters, combined with wild-cards, and other special characters,
+called meta-characters. The "meta-characters" have special meanings and are
+used to build complex patterns to be matched against. Perl Compatible Regular
+Expressions are an especially convenient "dialect" of the regular expression
+language.
+
+To make a simple analogy, we do something similar when we use wild-card
+characters when listing files with the dir command in DOS. *.* matches all
+filenames. The "special" character here is the asterisk which matches any and
+all characters. We can be more specific and use ? to match just individual
+characters. So "dir file?.text" would match "file1.txt", "file2.txt", etc. We
+are pattern matching, using a similar technique to "regular expressions"!
+
+Regular expressions do essentially the same thing, but are much, much more
+powerful. There are many more "special characters" and ways of building complex
+patterns however. Let's look at a few of the common ones, and then some
+examples:
+
+. - Matches any single character, e.g. "a", "A", "4", ":", or "@".
+
+? - The preceding character or expression is matched ZERO or ONE times. Either/
+or.
+
++ - The preceding character or expression is matched ONE or MORE times.
+
+* - The preceding character or expression is matched ZERO or MORE times.
+
+\ - The "escape" character denotes that the following character should be taken
+literally. This is used where one of the special characters (e.g. ".") needs to
+be taken literally and not as a special meta-character. Example: "example
+\.com", makes sure the period is recognized only as a period (and not expanded
+to its meta-character meaning of any single character).
+
+[] - Characters enclosed in brackets will be matched if any of the enclosed
+characters are encountered. For instance, "[0-9]" matches any numeric digit
+(zero through nine). As an example, we can combine this with "+" to match any
+digit one of more times: "[0-9]+".
+
+() - parentheses are used to group a sub-expression, or multiple
+sub-expressions.
+
+| - The "bar" character works like an "or" conditional statement. A match is
+successful if the sub-expression on either side of "|" matches. As an example:
+"/(this|that) example/" uses grouping and the bar character and would match
+either "this example" or "that example", and nothing else.
+
+These are just some of the ones you are likely to use when matching URLs with
+Privoxy, and is a long way from a definitive list. This is enough to get us
+started with a few simple examples which may be more illuminating:
+
+/.*/banners/.* - A simple example that uses the common combination of "." and "
+*" to denote any character, zero or more times. In other words, any string at
+all. So we start with a literal forward slash, then our regular expression
+pattern (".*") another literal forward slash, the string "banners", another
+forward slash, and lastly another ".*". We are building a directory path here.
+This will match any file with the path that has a directory named "banners" in
+it. The ".*" matches any characters, and this could conceivably be more forward
+slashes, so it might expand into a much longer looking path. For example, this
+could match: "/eye/hate/spammers/banners/annoy_me_please.gif", or just "/
+banners/annoying.html", or almost an infinite number of other possible
+combinations, just so it has "banners" in the path somewhere.
+
+A now something a little more complex:
+
+/.*/adv((er)?ts?|ertis(ing|ements?))?/ - We have several literal forward
+slashes again ("/"), so we are building another expression that is a file path
+statement. We have another ".*", so we are matching against any conceivable
+sub-path, just so it matches our expression. The only true literal that must
+match our pattern is adv, together with the forward slashes. What comes after
+the "adv" string is the interesting part.
+
+Remember the "?" means the preceding expression (either a literal character or
+anything grouped with "(...)" in this case) can exist or not, since this means
+either zero or one match. So "((er)?ts?|ertis(ing|ements?))" is optional, as
+are the individual sub-expressions: "(er)", "(ing|ements?)", and the "s". The "
+|" means "or". We have two of those. For instance, "(ing|ements?)", can expand
+to match either "ing" OR "ements?". What is being done here, is an attempt at
+matching as many variations of "advertisement", and similar, as possible. So
+this would expand to match just "adv", or "advert", or "adverts", or
+"advertising", or "advertisement", or "advertisements". You get the idea. But
+it would not match "advertizements" (with a "z"). We could fix that by changing
+our regular expression to: "/.*/adv((er)?ts?|erti(s|z)(ing|ements?))?/", which
+would then match either spelling.
+
+/.*/advert[0-9]+\.(gif|jpe?g) - Again another path statement with forward
+slashes. Anything in the square brackets "[]" can be matched. This is using
+"0-9" as a shorthand expression to mean any digit one through nine. It is the
+same as saying "0123456789". So any digit matches. The "+" means one or more of
+the preceding expression must be included. The preceding expression here is
+what is in the square brackets -- in this case, any digit one through nine.
+Then, at the end, we have a grouping: "(gif|jpe?g)". This includes a "|", so
+this needs to match the expression on either side of that bar character also. A
+simple "gif" on one side, and the other side will in turn match either "jpeg"
+or "jpg", since the "?" means the letter "e" is optional and can be matched
+once or not at all. So we are building an expression here to match image GIF or
+JPEG type image file. It must include the literal string "advert", then one or
+more digits, and a "." (which is now a literal, and not a special character,
+since it is escaped with "\"), and lastly either "gif", or "jpeg", or "jpg".
+Some possible matches would include: "//advert1.jpg", "/nasty/ads/
+advert1234.gif", "/banners/from/hell/advert99.jpg". It would not match
+"advert1.gif" (no leading slash), or "/adverts232.jpg" (the expression does not
+include an "s"), or "/advert1.jsp" ("jsp" is not in the expression anywhere).
+
+We are barely scratching the surface of regular expressions here so that you
+can understand the default Privoxy configuration files, and maybe use this
+knowledge to customize your own installation. There is much, much more that can
+be done with regular expressions. Now that you know enough to get started, you
+can learn more on your own :/
+
+More reading on Perl Compatible Regular expressions: http://www.perldoc.com/
+perl5.6/pod/perlre.html
+
+For information on regular expression based substitutions and their
+applications in filters, please see the filter file tutorial in this manual.
+
+-------------------------------------------------------------------------------
+
+14.2. Privoxy's Internal Pages
+
+Since Privoxy proxies each requested web page, it is easy for Privoxy to trap
+certain special URLs. In this way, we can talk directly to Privoxy, and see how
+it is configured, see how our rules are being applied, change these rules and
+other configuration options, and even turn Privoxy's filtering off, all with a
+web browser.
+
+The URLs listed below are the special ones that allow direct access to Privoxy.
+Of course, Privoxy must be running to access these. If not, you will get a
+friendly error message. Internet access is not necessary either.
+
+ * Privoxy main page:
+
+ http://config.privoxy.org/