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-
- <div class="SECT1">
- <h1 class="SECT1"><a name="FILTER-FILE" id="FILTER-FILE">9. Filter
- Files</a></h1>
-
- <p>On-the-fly text substitutions need to be defined in a <span class=
- "QUOTE">"filter file"</span>. Once defined, they can then be invoked as
- an <span class="QUOTE">"action"</span>.</p>
-
- <p><span class="APPLICATION">Privoxy</span> supports three different
- pcrs-based filter actions: <tt class="LITERAL"><a href=
- "actions-file.html#FILTER">filter</a></tt> to rewrite the content that is
- send to the client, <tt class="LITERAL"><a href=
- "actions-file.html#CLIENT-HEADER-FILTER">client-header-filter</a></tt> to
- rewrite headers that are send by the client, and <tt class=
- "LITERAL"><a href=
- "actions-file.html#SERVER-HEADER-FILTER">server-header-filter</a></tt> to
- rewrite headers that are send by the server.</p>
-
- <p><span class="APPLICATION">Privoxy</span> also supports two tagger
- actions: <tt class="LITERAL"><a href=
- "actions-file.html#CLIENT-HEADER-TAGGER">client-header-tagger</a></tt>
- and <tt class="LITERAL"><a href=
- "actions-file.html#SERVER-HEADER-TAGGER">server-header-tagger</a></tt>.
- Taggers and filters use the same syntax in the filter files, the
- difference is that taggers don't modify the text they are filtering, but
- use a rewritten version of the filtered text as tag. The tags can then be
- used to change the applying actions through sections with <a href=
- "actions-file.html#TAG-PATTERN">tag-patterns</a>.</p>
-
- <p>Finally <span class="APPLICATION">Privoxy</span> supports the
- <tt class="LITERAL"><a href=
- "actions-file.html#EXTERNAL-FILTER">external-filter</a></tt> action to
- enable <tt class="LITERAL"><a href=
- "filter-file.html#EXTERNAL-FILTER-SYNTAX">external filters</a></tt>
- written in proper programming languages.</p>
-
- <p>Multiple filter files can be defined through the <tt class=
- "LITERAL"><a href="config.html#FILTERFILE">filterfile</a></tt> config
- directive. The filters as supplied by the developers are located in
- <tt class="FILENAME">default.filter</tt>. It is recommended that any
- locally defined or modified filters go in a separately defined file such
- as <tt class="FILENAME">user.filter</tt>.</p>
-
- <p>Common tasks for content filters are to eliminate common annoyances in
- HTML and JavaScript, such as pop-up windows, exit consoles, crippled
- windows without navigation tools, the infamous <BLINK> tag etc, to
- suppress images with certain width and height attributes (standard banner
- sizes or web-bugs), or just to have fun.</p>
-
- <p>Enabled content filters are applied to any content whose <span class=
- "QUOTE">"Content Type"</span> header is recognised as a sign of
- text-based content, with the exception of <tt class=
- "LITERAL">text/plain</tt>. Use the <a href=
- "actions-file.html#FORCE-TEXT-MODE">force-text-mode</a> action to also
- filter other content.</p>
-
- <p>Substitutions are made at the source level, so if you want to
- <span class="QUOTE">"roll your own"</span> filters, you should first be
- familiar with HTML syntax, and, of course, regular expressions.</p>
-
- <p>Just like the <a href="actions-file.html">actions files</a>, the
- filter file is organized in sections, which are called <span class=
- "emphasis"><i class="EMPHASIS">filters</i></span> here. Each filter
- consists of a heading line, that starts with one of the <span class=
- "emphasis"><i class="EMPHASIS">keywords</i></span> <tt class=
- "LITERAL">FILTER:</tt>, <tt class="LITERAL">CLIENT-HEADER-FILTER:</tt> or
- <tt class="LITERAL">SERVER-HEADER-FILTER:</tt> followed by the filter's
- <span class="emphasis"><i class="EMPHASIS">name</i></span>, and a short
- (one line) <span class="emphasis"><i class=
- "EMPHASIS">description</i></span> of what it does. Below that line come
- the <span class="emphasis"><i class="EMPHASIS">jobs</i></span>, i.e.
- lines that define the actual text substitutions. By convention, the name
- of a filter should describe what the filter <span class=
- "emphasis"><i class="EMPHASIS">eliminates</i></span>. The comment is used
- in the <a href="http://config.privoxy.org/" target="_top">web-based user
- interface</a>.</p>
-
- <p>Once a filter called <tt class="REPLACEABLE"><i>name</i></tt> has been
- defined in the filter file, it can be invoked by using an action of the
- form +<tt class="LITERAL"><a href=
- "actions-file.html#FILTER">filter</a>{<tt class=
- "REPLACEABLE"><i>name</i></tt>}</tt> in any <a href=
- "actions-file.html">actions file</a>.</p>
-
- <p>Filter definitions start with a header line that contains the filter
- type, the filter name and the filter description. A content filter header
- line for a filter called <span class="QUOTE">"foo"</span> could look like
- this:</p>
-
- <table border="0" bgcolor="#E0E0E0" width="100%">
- <tr>
- <td>
- <pre class="SCREEN">
-FILTER: foo Replace all "foo" with "bar"
-</pre>
- </td>
- </tr>
- </table>
-
- <p>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 <a href="http://www.perl.org/" target=
- "_top">Perl</a>'s <tt class="LITERAL">s///</tt> operator. If you are
- familiar with Perl, you will find this to be quite intuitive, and may
- want to look at the PCRS documentation for the subtle differences to Perl
- behaviour.</p>
-
- <p>Most notably, the non-standard option letter <tt class=
- "LITERAL">U</tt> is supported, which turns the default to ungreedy
- matching (add <tt class="LITERAL">?</tt> to quantifiers to turn them
- greedy again).</p>
-
- <p>The non-standard option letter <tt class="LITERAL">D</tt> (dynamic)
- allows to use the variables $host, $origin (the IP address the request
- came from), $path, $url and $listen-address (the address on which Privoxy
- accepted the client request. Example: 127.0.0.1:8118). They will be
- replaced with the value they refer to before the filter is executed.</p>
-
- <p>Note that '$' is a bad choice for a delimiter in a dynamic filter as
- you might end up with unintended variables if you use a variable name
- directly after the delimiter. Variables will be resolved without escaping
- anything, therefore you also have to be careful not to chose delimiters
- that appear in the replacement text. For example '<' should be save,
- while '?' will sooner or later cause conflicts with $url.</p>
-
- <p>The non-standard option letter <tt class="LITERAL">T</tt> (trivial)
- prevents parsing for backreferences in the substitute. Use it if you want
- to include text like '$&' in your substitute without quoting.</p>
-
- <p>If you are new to <a href=
- "http://en.wikipedia.org/wiki/Regular_expressions" target=
- "_top"><span class="QUOTE">"Regular Expressions"</span></a>, you might
- want to take a look at the <a href="appendix.html#REGEX">Appendix on
- regular expressions</a>, and see the <a href=
- "http://perldoc.perl.org/perlre.html" target="_top">Perl manual</a> for
- <a href="http://perldoc.perl.org/perlop.html" target="_top">the
- <tt class="LITERAL">s///</tt> operator's syntax</a> and <a href=
- "http://perldoc.perl.org/perlre.html" target="_top">Perl-style regular
- expressions</a> in general. The below examples might also help to get you
- started.</p>
-
- <div class="SECT2">
- <h2 class="SECT2"><a name="FILTER-FILE-TUT" id="FILTER-FILE-TUT">9.1.
- Filter File Tutorial</a></h2>
-
- <p>Now, let's complete our <span class="QUOTE">"foo"</span> content
- filter. We have already defined the heading, but the jobs are still
- missing. Since all it does is to replace <span class=
- "QUOTE">"foo"</span> with <span class="QUOTE">"bar"</span>, there is
- only one (trivial) job needed:</p>
-
- <table border="0" bgcolor="#E0E0E0" width="100%">
+ <head>
+ <title>
+ Filter Files
+ </title>
+ <meta name="GENERATOR" content=
+ "Modular DocBook HTML Stylesheet Version 1.79">
+ <link rel="HOME" title="Privoxy 3.0.25 User Manual" href="index.html">
+ <link rel="PREVIOUS" title="Actions Files" href="actions-file.html">
+ <link rel="NEXT" title="Privoxy's Template Files" href="templates.html">
+ <link rel="STYLESHEET" type="text/css" href="../p_doc.css">
+ <meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
+ <link rel="STYLESHEET" type="text/css" href="p_doc.css">
+ </head>
+ <body class="SECT1" bgcolor="#EEEEEE" text="#000000" link="#0000FF" vlink=
+ "#840084" alink="#0000FF">
+ <div class="NAVHEADER">
+ <table summary="Header navigation table" width="100%" border="0"
+ cellpadding="0" cellspacing="0">
<tr>
- <td>
- <pre class="SCREEN">
-s/foo/bar/
-</pre>
+ <th colspan="3" align="center">
+ Privoxy 3.0.25 User Manual
+ </th>
+ </tr>
+ <tr>
+ <td width="10%" align="left" valign="bottom">
+ <a href="actions-file.html" accesskey="P">Prev</a>
+ </td>
+ <td width="80%" align="center" valign="bottom">
+ </td>
+ <td width="10%" align="right" valign="bottom">
+ <a href="templates.html" accesskey="N">Next</a>
</td>
</tr>
</table>
-
- <p>But wait! Didn't the comment say that <span class=
- "emphasis"><i class="EMPHASIS">all</i></span> occurrences of
- <span class="QUOTE">"foo"</span> should be replaced? Our current job
- will only take care of the first <span class="QUOTE">"foo"</span> on
- each page. For global substitution, we'll need to add the <tt class=
- "LITERAL">g</tt> option:</p>
-
+ <hr align="LEFT" width="100%">
+ </div>
+ <div class="SECT1">
+ <h1 class="SECT1">
+ <a name="FILTER-FILE">9. Filter Files</a>
+ </h1>
+ <p>
+ On-the-fly text substitutions need to be defined in a <span class=
+ "QUOTE">"filter file"</span>. Once defined, they can then be invoked
+ as an <span class="QUOTE">"action"</span>.
+ </p>
+ <p>
+ <span class="APPLICATION">Privoxy</span> supports three different
+ pcrs-based filter actions: <tt class="LITERAL"><a href=
+ "actions-file.html#FILTER">filter</a></tt> to rewrite the content
+ that is send to the client, <tt class="LITERAL"><a href=
+ "actions-file.html#CLIENT-HEADER-FILTER">client-header-filter</a></tt>
+ to rewrite headers that are send by the client, and <tt class=
+ "LITERAL"><a href=
+ "actions-file.html#SERVER-HEADER-FILTER">server-header-filter</a></tt>
+ to rewrite headers that are send by the server.
+ </p>
+ <p>
+ <span class="APPLICATION">Privoxy</span> also supports two tagger
+ actions: <tt class="LITERAL"><a href=
+ "actions-file.html#CLIENT-HEADER-TAGGER">client-header-tagger</a></tt>
+ and <tt class="LITERAL"><a href=
+ "actions-file.html#SERVER-HEADER-TAGGER">server-header-tagger</a></tt>.
+ Taggers and filters use the same syntax in the filter files, the
+ difference is that taggers don't modify the text they are filtering,
+ but use a rewritten version of the filtered text as tag. The tags can
+ then be used to change the applying actions through sections with <a
+ href="actions-file.html#TAG-PATTERN">tag-patterns</a>.
+ </p>
+ <p>
+ Finally <span class="APPLICATION">Privoxy</span> supports the <tt
+ class="LITERAL"><a href=
+ "actions-file.html#EXTERNAL-FILTER">external-filter</a></tt> action
+ to enable <tt class="LITERAL"><a href=
+ "filter-file.html#EXTERNAL-FILTER-SYNTAX">external filters</a></tt>
+ written in proper programming languages.
+ </p>
+ <p>
+ Multiple filter files can be defined through the <tt class=
+ "LITERAL"><a href="config.html#FILTERFILE">filterfile</a></tt> config
+ directive. The filters as supplied by the developers are located in
+ <tt class="FILENAME">default.filter</tt>. It is recommended that any
+ locally defined or modified filters go in a separately defined file
+ such as <tt class="FILENAME">user.filter</tt>.
+ </p>
+ <p>
+ Common tasks for content filters are to eliminate common annoyances
+ in HTML and JavaScript, such as pop-up windows, exit consoles,
+ crippled windows without navigation tools, the infamous <BLINK>
+ tag etc, to suppress images with certain width and height attributes
+ (standard banner sizes or web-bugs), or just to have fun.
+ </p>
+ <p>
+ Enabled content filters are applied to any content whose <span class=
+ "QUOTE">"Content Type"</span> header is recognised as a sign of
+ text-based content, with the exception of <tt class=
+ "LITERAL">text/plain</tt>. Use the <a href=
+ "actions-file.html#FORCE-TEXT-MODE">force-text-mode</a> action to
+ also filter other content.
+ </p>
+ <p>
+ Substitutions are made at the source level, so if you want to <span
+ class="QUOTE">"roll your own"</span> filters, you should first be
+ familiar with HTML syntax, and, of course, regular expressions.
+ </p>
+ <p>
+ Just like the <a href="actions-file.html">actions files</a>, the
+ filter file is organized in sections, which are called <span class=
+ "emphasis"><i class="EMPHASIS">filters</i></span> here. Each filter
+ consists of a heading line, that starts with one of the <span class=
+ "emphasis"><i class="EMPHASIS">keywords</i></span> <tt class=
+ "LITERAL">FILTER:</tt>, <tt class=
+ "LITERAL">CLIENT-HEADER-FILTER:</tt> or <tt class=
+ "LITERAL">SERVER-HEADER-FILTER:</tt> followed by the filter's <span
+ class="emphasis"><i class="EMPHASIS">name</i></span>, and a short
+ (one line) <span class="emphasis"><i class=
+ "EMPHASIS">description</i></span> of what it does. Below that line
+ come the <span class="emphasis"><i class="EMPHASIS">jobs</i></span>,
+ i.e. lines that define the actual text substitutions. By convention,
+ the name of a filter should describe what the filter <span class=
+ "emphasis"><i class="EMPHASIS">eliminates</i></span>. The comment is
+ used in the <a href="http://config.privoxy.org/" target=
+ "_top">web-based user interface</a>.
+ </p>
+ <p>
+ Once a filter called <tt class="REPLACEABLE"><i>name</i></tt> has
+ been defined in the filter file, it can be invoked by using an action
+ of the form +<tt class="LITERAL"><a href=
+ "actions-file.html#FILTER">filter</a>{<tt class=
+ "REPLACEABLE"><i>name</i></tt>}</tt> in any <a href=
+ "actions-file.html">actions file</a>.
+ </p>
+ <p>
+ Filter definitions start with a header line that contains the filter
+ type, the filter name and the filter description. A content filter
+ header line for a filter called <span class="QUOTE">"foo"</span>
+ could look like this:
+ </p>
+ <p>
+ </p>
<table border="0" bgcolor="#E0E0E0" width="100%">
<tr>
<td>
-s/foo/bar/g
+<pre class="SCREEN">
+FILTER: foo Replace all "foo" with "bar"
</pre>
</td>
</tr>
</table>
- <p>Our complete filter now looks like this:</p>
+ <p>
+ 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 <a href="http://www.perl.org/" target=
+ "_top">Perl</a>'s <tt class="LITERAL">s///</tt> operator. If you are
+ familiar with Perl, you will find this to be quite intuitive, and may
+ want to look at the PCRS documentation for the subtle differences to
+ Perl behaviour.
+ </p>
+ <p>
+ Most notably, the non-standard option letter <tt class=
+ "LITERAL">U</tt> is supported, which turns the default to ungreedy
+ matching (add <tt class="LITERAL">?</tt> to quantifiers to turn them
+ greedy again).
+ </p>
+ <p>
+ The non-standard option letter <tt class="LITERAL">D</tt> (dynamic)
+ allows to use the variables $host, $origin (the IP address the
+ request came from), $path, $url and $listen-address (the address on
+ which Privoxy accepted the client request. Example: 127.0.0.1:8118).
+ They will be replaced with the value they refer to before the filter
+ is executed.
+ </p>
+ <p>
+ Note that '$' is a bad choice for a delimiter in a dynamic filter as
+ you might end up with unintended variables if you use a variable name
+ directly after the delimiter. Variables will be resolved without
+ escaping anything, therefore you also have to be careful not to chose
+ delimiters that appear in the replacement text. For example '<'
+ should be save, while '?' will sooner or later cause conflicts with
+ $url.
+ </p>
+ <p>
+ The non-standard option letter <tt class="LITERAL">T</tt> (trivial)
+ prevents parsing for backreferences in the substitute. Use it if you
+ want to include text like '$&' in your substitute without
+ quoting.
+ </p>
+ <p>
+ If you are new to <a href=
+ "http://en.wikipedia.org/wiki/Regular_expressions" target=
+ "_top"><span class="QUOTE">"Regular Expressions"</span></a>, you
+ might want to take a look at the <a href=
+ "appendix.html#REGEX">Appendix on regular expressions</a>, and see
+ the <a href="http://perldoc.perl.org/perlre.html" target="_top">Perl
+ manual</a> for <a href="http://perldoc.perl.org/perlop.html" target=
+ "_top">the <tt class="LITERAL">s///</tt> operator's syntax</a> and <a
+ href="http://perldoc.perl.org/perlre.html" target="_top">Perl-style
+ regular expressions</a> in general. The below examples might also
+ help to get you started.
+ </p>
+ <div class="SECT2">
+ <h2 class="SECT2">
+ <a name="FILTER-FILE-TUT">9.1. Filter File Tutorial</a>
+ </h2>
+ <p>
+ Now, let's complete our <span class="QUOTE">"foo"</span> content
+ filter. We have already defined the heading, but the jobs are still
+ missing. Since all it does is to replace <span class=
+ "QUOTE">"foo"</span> with <span class="QUOTE">"bar"</span>, there
+ is only one (trivial) job needed:
+ </p>
+ <p>
+ </p>
+ <table border="0" bgcolor="#E0E0E0" width="100%">
+ <tr>
+ <td>
+<pre class="SCREEN">
+s/foo/bar/
+</pre>
+ </td>
+ </tr>
+ </table>
- <table border="0" bgcolor="#E0E0E0" width="100%">
- <tr>
- <td>
- <pre class="SCREEN">
-FILTER: foo Replace all "foo" with "bar"
+ <p>
+ But wait! Didn't the comment say that <span class="emphasis"><i
+ class="EMPHASIS">all</i></span> occurrences of <span class=
+ "QUOTE">"foo"</span> should be replaced? Our current job will only
+ take care of the first <span class="QUOTE">"foo"</span> on each
+ page. For global substitution, we'll need to add the <tt class=
+ "LITERAL">g</tt> option:
+ </p>
+ <p>
+ </p>
+ <table border="0" bgcolor="#E0E0E0" width="100%">
+ <tr>
+ <td>
+<pre class="SCREEN">
s/foo/bar/g
</pre>
- </td>
- </tr>
- </table>
+ </td>
+ </tr>
+ </table>
- <p>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:</p>
+ <p>
+ Our complete filter now looks like this:
+ </p>
+ <p>
+ </p>
+ <table border="0" bgcolor="#E0E0E0" width="100%">
+ <tr>
+ <td>
+<pre class="SCREEN">
+FILTER: foo Replace all "foo" with "bar"
+s/foo/bar/g
+</pre>
+ </td>
+ </tr>
+ </table>
- <table border="0" bgcolor="#E0E0E0" width="100%">
- <tr>
- <td>
- <pre class="SCREEN">
+ <p>
+ 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:
+ </p>
+ <p>
+ </p>
+ <table border="0" bgcolor="#E0E0E0" width="100%">
+ <tr>
+ <td>
+<pre class="SCREEN">
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
</pre>
- </td>
- </tr>
- </table>
-
- <p>Following the header line and a comment, you see the job. Note that
- it uses <tt class="LITERAL">|</tt> as the delimiter instead of
- <tt class="LITERAL">/</tt>, because the pattern contains a forward
- slash, which would otherwise have to be escaped by a backslash
- (<tt class="LITERAL">\</tt>).</p>
-
- <p>Now, let's examine the pattern: it starts with the text <tt class=
- "LITERAL"><script.*</tt> enclosed in parentheses. Since the dot
- matches any character, and <tt class="LITERAL">*</tt> means:
- <span class="QUOTE">"Match an arbitrary number of the element left of
- myself"</span>, this matches <span class="QUOTE">"<script"</span>,
- followed by <span class="emphasis"><i class="EMPHASIS">any</i></span>
- text, i.e. it matches the whole page, from the start of the first
- <script> tag.</p>
-
- <p>That's more than we want, but the pattern continues: <tt class=
- "LITERAL">document\.referrer</tt> matches only the exact string
- <span class="QUOTE">"document.referrer"</span>. The dot needed to be
- <span class="emphasis"><i class="EMPHASIS">escaped</i></span>, 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 <span class="QUOTE">"document.referrer"</span>, if
- <span class="emphasis"><i class="EMPHASIS">both</i></span> are present
- in the page (and appear in that order).</p>
-
- <p>But there's still more pattern to go. The next element, again
- enclosed in parentheses, is <tt class="LITERAL">.*</script></tt>.
- You already know what <tt class="LITERAL">.*</tt> 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 <span class="QUOTE">"document.referrer"</span> appears
- somewhere in between.</p>
-
- <p>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 <tt class="LITERAL">$1, $2, ...</tt> in the
- substitute. The <tt class="LITERAL">U</tt> option switches to ungreedy
- matching, which means that the first <tt class="LITERAL">.*</tt> in the
- pattern will only <span class="QUOTE">"eat up"</span> all text in
- between <span class="QUOTE">"<script"</span> and the <span class=
- "emphasis"><i class="EMPHASIS">first</i></span> occurrence of
- <span class="QUOTE">"document.referrer"</span>, and that the second
- <tt class="LITERAL">.*</tt> will only span the text up to the
- <span class="emphasis"><i class="EMPHASIS">first</i></span>
- <span class="QUOTE">"</script>"</span> tag. Furthermore, the
- <tt class="LITERAL">s</tt> option says that the match may span multiple
- lines in the page, and the <tt class="LITERAL">g</tt> option again
- means that the substitution is global.</p>
-
- <p>So, to summarize, the pattern means: Match all scripts that contain
- the text <span class="QUOTE">"document.referrer"</span>. Remember the
- parts of the script from (and including) the start tag up to (and
- excluding) the string <span class="QUOTE">"document.referrer"</span> as
- <tt class="LITERAL">$1</tt>, and the part following that string, up to
- and including the closing tag, as <tt class="LITERAL">$2</tt>.</p>
-
- <p>Now the pattern is deciphered, but wasn't this about substituting
- things? So lets look at the substitute: <tt class="LITERAL">$1"Not Your
- Business!"$2</tt> is easy to read: The text remembered as <tt class=
- "LITERAL">$1</tt>, followed by <tt class="LITERAL">"Not Your
- Business!"</tt> (<span class="emphasis"><i class=
- "EMPHASIS">including</i></span> the quotation marks!), followed by the
- text remembered as <tt class="LITERAL">$2</tt>. This produces an exact
- copy of the original string, with the middle part (the <span class=
- "QUOTE">"document.referrer"</span>) replaced by <tt class=
- "LITERAL">"Not Your Business!"</tt>.</p>
-
- <p>The whole job now reads: Replace <span class=
- "QUOTE">"document.referrer"</span> by <tt class="LITERAL">"Not Your
- Business!"</tt> 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.</p>
-
- <p>We'll show you two other jobs from the JavaScript taming department,
- but this time only point out the constructs of special interest:</p>
+ </td>
+ </tr>
+ </table>
- <table border="0" bgcolor="#E0E0E0" width="100%">
- <tr>
- <td>
- <pre class="SCREEN">
+ <p>
+ Following the header line and a comment, you see the job. Note that
+ it uses <tt class="LITERAL">|</tt> as the delimiter instead of <tt
+ class="LITERAL">/</tt>, because the pattern contains a forward
+ slash, which would otherwise have to be escaped by a backslash (<tt
+ class="LITERAL">\</tt>).
+ </p>
+ <p>
+ Now, let's examine the pattern: it starts with the text <tt class=
+ "LITERAL"><script.*</tt> enclosed in parentheses. Since the dot
+ matches any character, and <tt class="LITERAL">*</tt> means: <span
+ class="QUOTE">"Match an arbitrary number of the element left of
+ myself"</span>, this matches <span class=
+ "QUOTE">"<script"</span>, followed by <span class="emphasis"><i
+ class="EMPHASIS">any</i></span> text, i.e. it matches the whole
+ page, from the start of the first <script> tag.
+ </p>
+ <p>
+ That's more than we want, but the pattern continues: <tt class=
+ "LITERAL">document\.referrer</tt> matches only the exact string
+ <span class="QUOTE">"document.referrer"</span>. The dot needed to
+ be <span class="emphasis"><i class="EMPHASIS">escaped</i></span>,
+ 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 <span class=
+ "QUOTE">"document.referrer"</span>, if <span class="emphasis"><i
+ class="EMPHASIS">both</i></span> are present in the page (and
+ appear in that order).
+ </p>
+ <p>
+ But there's still more pattern to go. The next element, again
+ enclosed in parentheses, is <tt class=
+ "LITERAL">.*</script></tt>. You already know what <tt class=
+ "LITERAL">.*</tt> 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 <span class=
+ "QUOTE">"document.referrer"</span> appears somewhere in between.
+ </p>
+ <p>
+ 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 <tt class="LITERAL">$1, $2,
+ ...</tt> in the substitute. The <tt class="LITERAL">U</tt> option
+ switches to ungreedy matching, which means that the first <tt
+ class="LITERAL">.*</tt> in the pattern will only <span class=
+ "QUOTE">"eat up"</span> all text in between <span class=
+ "QUOTE">"<script"</span> and the <span class="emphasis"><i
+ class="EMPHASIS">first</i></span> occurrence of <span class=
+ "QUOTE">"document.referrer"</span>, and that the second <tt class=
+ "LITERAL">.*</tt> will only span the text up to the <span class=
+ "emphasis"><i class="EMPHASIS">first</i></span> <span class=
+ "QUOTE">"</script>"</span> tag. Furthermore, the <tt class=
+ "LITERAL">s</tt> option says that the match may span multiple lines
+ in the page, and the <tt class="LITERAL">g</tt> option again means
+ that the substitution is global.
+ </p>
+ <p>
+ So, to summarize, the pattern means: Match all scripts that contain
+ the text <span class="QUOTE">"document.referrer"</span>. Remember
+ the parts of the script from (and including) the start tag up to
+ (and excluding) the string <span class=
+ "QUOTE">"document.referrer"</span> as <tt class="LITERAL">$1</tt>,
+ and the part following that string, up to and including the closing
+ tag, as <tt class="LITERAL">$2</tt>.
+ </p>
+ <p>
+ Now the pattern is deciphered, but wasn't this about substituting
+ things? So lets look at the substitute: <tt class="LITERAL">$1"Not
+ Your Business!"$2</tt> is easy to read: The text remembered as <tt
+ class="LITERAL">$1</tt>, followed by <tt class="LITERAL">"Not Your
+ Business!"</tt> (<span class="emphasis"><i class=
+ "EMPHASIS">including</i></span> the quotation marks!), followed by
+ the text remembered as <tt class="LITERAL">$2</tt>. This produces
+ an exact copy of the original string, with the middle part (the
+ <span class="QUOTE">"document.referrer"</span>) replaced by <tt
+ class="LITERAL">"Not Your Business!"</tt>.
+ </p>
+ <p>
+ The whole job now reads: Replace <span class=
+ "QUOTE">"document.referrer"</span> by <tt class="LITERAL">"Not Your
+ Business!"</tt> 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.
+ </p>
+ <p>
+ We'll show you two other jobs from the JavaScript taming
+ department, but this time only point out the constructs of special
+ interest:
+ </p>
+ <p>
+ </p>
+ <table border="0" bgcolor="#E0E0E0" width="100%">
+ <tr>
+ <td>
+<pre class="SCREEN">
# The status bar is for displaying link targets, not pointless blahblah
#
s/window\.status\s*=\s*(['"]).*?\1/dUmMy=1/ig
</pre>
- </td>
- </tr>
- </table>
-
- <p><tt class="LITERAL">\s</tt> stands for whitespace characters (space,
- tab, newline, carriage return, form feed), so that <tt class=
- "LITERAL">\s*</tt> means: <span class="QUOTE">"zero or more
- whitespace"</span>. The <tt class="LITERAL">?</tt> in <tt class=
- "LITERAL">.*?</tt> makes this matching of arbitrary text ungreedy.
- (Note that the <tt class="LITERAL">U</tt> option is not set). The
- <tt class="LITERAL">['"]</tt> construct means: <span class="QUOTE">"a
- single <span class="emphasis"><i class="EMPHASIS">or</i></span> a
- double quote"</span>. Finally, <tt class="LITERAL">\1</tt> is a
- back-reference to the first parenthesis just like <tt class=
- "LITERAL">$1</tt> above, with the difference that in the <span class=
- "emphasis"><i class="EMPHASIS">pattern</i></span>, a backslash
- indicates a back-reference, whereas in the <span class=
- "emphasis"><i class="EMPHASIS">substitute</i></span>, it's the
- dollar.</p>
-
- <p>So what does this job do? It replaces assignments of single- or
- double-quoted strings to the <span class="QUOTE">"window.status"</span>
- 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.</p>
+ </td>
+ </tr>
+ </table>
- <table border="0" bgcolor="#E0E0E0" width="100%">
- <tr>
- <td>
- <pre class="SCREEN">
+ <p>
+ <tt class="LITERAL">\s</tt> stands for whitespace characters
+ (space, tab, newline, carriage return, form feed), so that <tt
+ class="LITERAL">\s*</tt> means: <span class="QUOTE">"zero or more
+ whitespace"</span>. The <tt class="LITERAL">?</tt> in <tt class=
+ "LITERAL">.*?</tt> makes this matching of arbitrary text ungreedy.
+ (Note that the <tt class="LITERAL">U</tt> option is not set). The
+ <tt class="LITERAL">['"]</tt> construct means: <span class=
+ "QUOTE">"a single <span class="emphasis"><i class=
+ "EMPHASIS">or</i></span> a double quote"</span>. Finally, <tt
+ class="LITERAL">\1</tt> is a back-reference to the first
+ parenthesis just like <tt class="LITERAL">$1</tt> above, with the
+ difference that in the <span class="emphasis"><i class=
+ "EMPHASIS">pattern</i></span>, a backslash indicates a
+ back-reference, whereas in the <span class="emphasis"><i class=
+ "EMPHASIS">substitute</i></span>, it's the dollar.
+ </p>
+ <p>
+ So what does this job do? It replaces assignments of single- or
+ double-quoted strings to the <span class=
+ "QUOTE">"window.status"</span> 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.
+ </p>
+ <p>
+ </p>
+ <table border="0" bgcolor="#E0E0E0" width="100%">
+ <tr>
+ <td>
+<pre class="SCREEN">
# Kill OnUnload popups. Yummy. Test: http://www.zdnet.com/zdsubs/yahoo/tree/yfs.html
#
s/(<body [^>]*)onunload(.*>)/$1never$2/iU
</pre>
- </td>
- </tr>
- </table>
-
- <p>Including the <a href=
- "http://www.w3.org/TR/2000/REC-DOM-Level-2-Events-20001113/events.html#Events-eventgroupings-htmlevents"
- target="_top">OnUnload event binding</a> in the HTML DOM was a
- <span class="emphasis"><i class="EMPHASIS">CRIME</i></span>. When I
- close a browser window, I want it to close and die. Basta. This job
- replaces the <span class="QUOTE">"onunload"</span> attribute in
- <span class="QUOTE">"<body>"</span> tags with the dummy word
- <tt class="LITERAL">never</tt>. Note that the <tt class=
- "LITERAL">i</tt> 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 <tt class=
- "LITERAL">[^>]*</tt> instead of <tt class="LITERAL">.*</tt> to
- prevent the match from exceeding the <body> tag if it doesn't
- contain <span class="QUOTE">"OnUnload"</span>, but the page's content
- does.</p>
-
- <p>The last example is from the fun department:</p>
+ </td>
+ </tr>
+ </table>
- <table border="0" bgcolor="#E0E0E0" width="100%">
- <tr>
- <td>
- <pre class="SCREEN">
+ <p>
+ Including the <a href=
+ "http://www.w3.org/TR/2000/REC-DOM-Level-2-Events-20001113/events.html#Events-eventgroupings-htmlevents"
+ target="_top">OnUnload event binding</a> in the HTML DOM was a
+ <span class="emphasis"><i class="EMPHASIS">CRIME</i></span>. When I
+ close a browser window, I want it to close and die. Basta. This job
+ replaces the <span class="QUOTE">"onunload"</span> attribute in
+ <span class="QUOTE">"<body>"</span> tags with the dummy word
+ <tt class="LITERAL">never</tt>. Note that the <tt class=
+ "LITERAL">i</tt> 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 <tt class="LITERAL">[^>]*</tt> instead of <tt class=
+ "LITERAL">.*</tt> to prevent the match from exceeding the
+ <body> tag if it doesn't contain <span class=
+ "QUOTE">"OnUnload"</span>, but the page's content does.
+ </p>
+ <p>
+ The last example is from the fun department:
+ </p>
+ <p>
+ </p>
+ <table border="0" bgcolor="#E0E0E0" width="100%">
+ <tr>
+ <td>
+<pre class="SCREEN">
FILTER: fun Fun text replacements
# Spice the daily news:
#
s/microsoft(?!\.com)/MicroSuck/ig
</pre>
- </td>
- </tr>
- </table>
-
- <p>Note the <tt class="LITERAL">(?!\.com)</tt> part (a so-called
- negative lookahead) in the job's pattern, which means: Don't match, if
- the string <span class="QUOTE">".com"</span> appears directly following
- <span class="QUOTE">"microsoft"</span> in the page. This prevents links
- to microsoft.com from being trashed, while still replacing the word
- everywhere else.</p>
+ </td>
+ </tr>
+ </table>
- <table border="0" bgcolor="#E0E0E0" width="100%">
- <tr>
- <td>
- <pre class="SCREEN">
+ <p>
+ Note the <tt class="LITERAL">(?!\.com)</tt> part (a so-called
+ negative lookahead) in the job's pattern, which means: Don't match,
+ if the string <span class="QUOTE">".com"</span> appears directly
+ following <span class="QUOTE">"microsoft"</span> in the page. This
+ prevents links to microsoft.com from being trashed, while still
+ replacing the word everywhere else.
+ </p>
+ <p>
+ </p>
+ <table border="0" bgcolor="#E0E0E0" width="100%">
+ <tr>
+ <td>
+<pre class="SCREEN">
# Buzzword Bingo (example for extended regex syntax)
#
s* industry[ -]leading \
*<font color="red"><b>BINGO!</b></font> \
*igx
</pre>
- </td>
- </tr>
- </table>
-
- <p>The <tt class="LITERAL">x</tt> option in this job turns on extended
- syntax, and allows for e.g. the liberal use of (non-interpreted!)
- whitespace for nicer formatting.</p>
-
- <p>You get the idea?</p>
- </div>
-
- <div class="SECT2">
- <h2 class="SECT2"><a name="PREDEFINED-FILTERS" id=
- "PREDEFINED-FILTERS">9.2. The Pre-defined Filters</a></h2>
-
- <p>The distribution <tt class="FILENAME">default.filter</tt> file
- contains a selection of pre-defined filters for your convenience:</p>
-
- <div class="VARIABLELIST">
- <dl>
- <dt><span class="emphasis"><i class=
- "EMPHASIS">js-annoyances</i></span></dt>
-
- <dd>
- <p>The purpose of this filter is to get rid of particularly
- annoying JavaScript abuse. To that end, it</p>
-
- <ul>
- <li>
- <p>replaces JavaScript references to the browser's referrer
- information with the string "Not Your Business!". This
- compliments the <tt class="LITERAL"><a href=
- "actions-file.html#HIDE-REFERRER">hide-referrer</a></tt>
- action on the content level.</p>
- </li>
-
- <li>
- <p>removes the bindings to the DOM's <a href=
- "http://www.w3.org/TR/2000/REC-DOM-Level-2-Events-20001113/events.html#Events-eventgroupings-htmlevents"
- target="_top">unload event</a> which we feel has no right to
- exist and is responsible for most <span class="QUOTE">"exit
- consoles"</span>, i.e. nasty windows that pop up when you
- close another one.</p>
- </li>
-
- <li>
- <p>removes code that causes new windows to be opened with
- undesired properties, such as being full-screen,
- non-resizeable, without location, status or menu bar etc.</p>
- </li>
- </ul>
-
- <p>Use with caution. This is an aggressive filter, and can break
- sites that rely heavily on JavaScript.</p>
- </dd>
-
- <dt><span class="emphasis"><i class=
- "EMPHASIS">js-events</i></span></dt>
-
- <dd>
- <p>This is a very radical measure. It removes virtually all
- JavaScript event bindings, which means that scripts can not react
- to user actions such as mouse movements or clicks, window
- resizing etc, anymore. Use with caution!</p>
-
- <p>We <span class="emphasis"><i class="EMPHASIS">strongly
- discourage</i></span> using this filter as a default since it
- breaks many legitimate scripts. It is meant for use only on
- extra-nasty sites (should you really need to go there).</p>
- </dd>
-
- <dt><span class="emphasis"><i class=
- "EMPHASIS">html-annoyances</i></span></dt>
-
- <dd>
- <p>This filter will undo many common instances of HTML based
- abuse.</p>
-
- <p>The <tt class="LITERAL">BLINK</tt> and <tt class=
- "LITERAL">MARQUEE</tt> tags are neutralized (yeah baby!), and
- browser windows will be created as resizeable (as of course they
- should be!), and will have location, scroll and menu bars -- even
- if specified otherwise.</p>
- </dd>
-
- <dt><span class="emphasis"><i class=
- "EMPHASIS">content-cookies</i></span></dt>
-
- <dd>
- <p>Most cookies are set in the HTTP dialog, where they can be
- intercepted by the <tt class="LITERAL"><a href=
- "actions-file.html#CRUNCH-INCOMING-COOKIES">crunch-incoming-cookies</a></tt>
- and <tt class="LITERAL"><a href=
- "actions-file.html#CRUNCH-OUTGOING-COOKIES">crunch-outgoing-cookies</a></tt>
- actions. But web sites increasingly make use of HTML meta tags
- and JavaScript to sneak cookies to the browser on the content
- level.</p>
-
- <p>This filter disables most HTML and JavaScript code that reads
- or sets cookies. It cannot detect all clever uses of these types
- of code, so it should not be relied on as an absolute fix. Use it
- wherever you would also use the cookie crunch actions.</p>
- </dd>
-
- <dt><span class="emphasis"><i class=
- "EMPHASIS">refresh-tags</i></span></dt>
-
- <dd>
- <p>Disable any refresh tags if the interval is greater than nine
- seconds (so that redirections done via refresh tags are not
- destroyed). This is useful for dial-on-demand setups, or for
- those who find this HTML feature annoying.</p>
- </dd>
-
- <dt><span class="emphasis"><i class=
- "EMPHASIS">unsolicited-popups</i></span></dt>
-
- <dd>
- <p>This filter attempts to prevent only <span class=
- "QUOTE">"unsolicited"</span> pop-up windows from opening, yet
- still allow pop-up windows that the user has explicitly chosen to
- open. It was added in version 3.0.1, as an improvement over
- earlier such filters.</p>
-
- <p>Technical note: The filter works by redefining the window.open
- JavaScript function to a dummy function, <tt class=
- "LITERAL">PrivoxyWindowOpen()</tt>, during the loading and
- rendering phase of each HTML page access, and restoring the
- function afterward.</p>
-
- <p>This is recommended only for browsers that cannot perform this
- function reliably themselves. And be aware that some sites
- require such windows in order to function normally. Use with
- caution.</p>
- </dd>
-
- <dt><span class="emphasis"><i class=
- "EMPHASIS">all-popups</i></span></dt>
-
- <dd>
- <p>Attempt to prevent <span class="emphasis"><i class=
- "EMPHASIS">all</i></span> pop-up windows from opening. Note this
- should be used with even more discretion than the above, since it
- is more likely to break some sites that require pop-ups for
- normal usage. Use with caution.</p>
- </dd>
-
- <dt><span class="emphasis"><i class=
- "EMPHASIS">img-reorder</i></span></dt>
-
- <dd>
- <p>This is a helper filter that has no value if used alone. It
- makes the <tt class="LITERAL">banners-by-size</tt> and <tt class=
- "LITERAL">banners-by-link</tt> (see below) filters more effective
- and should be enabled together with them.</p>
- </dd>
-
- <dt><span class="emphasis"><i class=
- "EMPHASIS">banners-by-size</i></span></dt>
-
- <dd>
- <p>This filter removes image tags purely based on what size they
- are. Fortunately for us, many ads and banner images tend to
- conform to certain standardized sizes, which makes this filter
- quite effective for ad stripping purposes.</p>
-
- <p>Occasionally this filter will cause false positives on images
- that are not ads, but just happen to be of one of the standard
- banner sizes.</p>
-
- <p>Recommended only for those who require extreme ad blocking.
- The default block rules should catch 95+% of all ads <span class=
- "emphasis"><i class="EMPHASIS">without</i></span> this filter
- enabled.</p>
- </dd>
-
- <dt><span class="emphasis"><i class=
- "EMPHASIS">banners-by-link</i></span></dt>
-
- <dd>
- <p>This is an experimental filter that attempts to kill any
- banners if their URLs seem to point to known or suspected click
- trackers. It is currently not of much value and is not
- recommended for use by default.</p>
- </dd>
-
- <dt><span class="emphasis"><i class=
- "EMPHASIS">webbugs</i></span></dt>
-
- <dd>
- <p>Webbugs are small, invisible images (technically 1X1 GIF
- images), that are used to track users across websites, and
- collect information on them. As an HTML page is loaded by the
- browser, an embedded image tag causes the browser to contact a
- third-party site, disclosing the tracking information through the
- requested URL and/or cookies for that third-party domain, without
- the user ever becoming aware of the interaction with the
- third-party site. HTML-ized spam also uses a similar technique to
- verify email addresses.</p>
-
- <p>This filter removes the HTML code that loads such <span class=
- "QUOTE">"webbugs"</span>.</p>
- </dd>
-
- <dt><span class="emphasis"><i class=
- "EMPHASIS">tiny-textforms</i></span></dt>
-
- <dd>
- <p>A rather special-purpose filter that can be used to enlarge
- textareas (those multi-line text boxes in web forms) and turn off
- hard word wrap in them. It was written for the sourceforge.net
- tracker system where such boxes are a nuisance, but it can be
- handy on other sites, too.</p>
-
- <p>It is not recommended to use this filter as a default.</p>
- </dd>
-
- <dt><span class="emphasis"><i class=
- "EMPHASIS">jumping-windows</i></span></dt>
-
- <dd>
- <p>Many consider windows that move, or resize themselves to be
- abusive. This filter neutralizes the related JavaScript code.
- Note that some sites might not display or behave as intended when
- using this filter. Use with caution.</p>
- </dd>
-
- <dt><span class="emphasis"><i class=
- "EMPHASIS">frameset-borders</i></span></dt>
-
- <dd>
- <p>Some web designers seem to assume that everyone in the world
- will view their web sites using the same browser brand and
- version, screen resolution etc, because only that assumption
- could explain why they'd use static frame sizes, yet prevent
- their frames from being resized by the user, should they be too
- small to show their whole content.</p>
-
- <p>This filter removes the related HTML code. It should only be
- applied to sites which need it.</p>
- </dd>
-
- <dt><span class="emphasis"><i class=
- "EMPHASIS">demoronizer</i></span></dt>
-
- <dd>
- <p>Many Microsoft products that generate HTML use non-standard
- extensions (read: violations) of the ISO 8859-1 aka Latin-1
- character set. This can cause those HTML documents to display
- with errors on standard-compliant platforms.</p>
-
- <p>This filter translates the MS-only characters into Latin-1
- equivalents. It is not necessary when using MS products, and will
- cause corruption of all documents that use 8-bit character sets
- other than Latin-1. It's mostly worthwhile for Europeans on
- non-MS platforms, if weird garbage characters sometimes appear on
- some pages, or user agents that don't correct for this on the
- fly.</p>
- </dd>
-
- <dt><span class="emphasis"><i class=
- "EMPHASIS">shockwave-flash</i></span></dt>
-
- <dd>
- <p>A filter for shockwave haters. As the name suggests, this
- filter strips code out of web pages that is used to embed
- shockwave flash objects.</p>
- </dd>
-
- <dt><span class="emphasis"><i class=
- "EMPHASIS">quicktime-kioskmode</i></span></dt>
-
- <dd>
- <p>Change HTML code that embeds Quicktime objects so that
- kioskmode, which prevents saving, is disabled.</p>
- </dd>
-
- <dt><span class="emphasis"><i class="EMPHASIS">fun</i></span></dt>
-
- <dd>
- <p>Text replacements for subversive browsing fun. Make fun of
- your favorite Monopolist or play buzzword bingo.</p>
- </dd>
-
- <dt><span class="emphasis"><i class=
- "EMPHASIS">crude-parental</i></span></dt>
-
- <dd>
- <p>A demonstration-only filter that shows how <span class=
- "APPLICATION">Privoxy</span> can be used to delete web content on
- a keyword basis.</p>
- </dd>
-
- <dt><span class="emphasis"><i class=
- "EMPHASIS">ie-exploits</i></span></dt>
-
- <dd>
- <p>An experimental collection of text replacements to disable
- malicious HTML and JavaScript code that exploits known security
- holes in Internet Explorer.</p>
-
- <p>Presently, it only protects against Nimda and a cross-site
- scripting bug, and would need active maintenance to provide more
- substantial protection.</p>
- </dd>
-
- <dt><span class="emphasis"><i class=
- "EMPHASIS">site-specifics</i></span></dt>
-
- <dd>
- <p>Some web sites have very specific problems, the cure for which
- doesn't apply anywhere else, or could even cause damage on other
- sites.</p>
-
- <p>This is a collection of such site-specific cures which should
- only be applied to the sites they were intended for, which is
- what the supplied <tt class="FILENAME">default.action</tt> file
- does. Users shouldn't need to change anything regarding this
- filter.</p>
- </dd>
-
- <dt><span class="emphasis"><i class=
- "EMPHASIS">google</i></span></dt>
-
- <dd>
- <p>A CSS based block for Google text ads. Also removes a width
- limitation and the toolbar advertisement.</p>
- </dd>
-
- <dt><span class="emphasis"><i class=
- "EMPHASIS">yahoo</i></span></dt>
-
- <dd>
- <p>Another CSS based block, this time for Yahoo text ads. And
- removes a width limitation as well.</p>
- </dd>
-
- <dt><span class="emphasis"><i class="EMPHASIS">msn</i></span></dt>
-
- <dd>
- <p>Another CSS based block, this time for MSN text ads. And
- removes tracking URLs, as well as a width limitation.</p>
- </dd>
-
- <dt><span class="emphasis"><i class=
- "EMPHASIS">blogspot</i></span></dt>
-
- <dd>
- <p>Cleans up some Blogspot blogs. Read the fine print before
- using this one!</p>
-
- <p>This filter also intentionally removes some navigation stuff
- and sets the page width to 100%. As a result, some rounded
- <span class="QUOTE">"corners"</span> would appear to early or not
- at all and as fixing this would require a browser that
- understands background-size (CSS3), they are removed instead.</p>
- </dd>
-
- <dt><span class="emphasis"><i class=
- "EMPHASIS">xml-to-html</i></span></dt>
-
- <dd>
- <p>Server-header filter to change the Content-Type from xml to
- html.</p>
- </dd>
-
- <dt><span class="emphasis"><i class=
- "EMPHASIS">html-to-xml</i></span></dt>
-
- <dd>
- <p>Server-header filter to change the Content-Type from html to
- xml.</p>
- </dd>
-
- <dt><span class="emphasis"><i class=
- "EMPHASIS">no-ping</i></span></dt>
-
- <dd>
- <p>Removes the non-standard <tt class="LITERAL">ping</tt>
- attribute from anchor and area HTML tags.</p>
- </dd>
-
- <dt><span class="emphasis"><i class=
- "EMPHASIS">hide-tor-exit-notation</i></span></dt>
-
- <dd>
- <p>Client-header filter to remove the <b class="COMMAND">Tor</b>
- exit node notation found in Host and Referer headers.</p>
-
- <p>If <span class="APPLICATION">Privoxy</span> and <b class=
- "COMMAND">Tor</b> are chained and <span class=
- "APPLICATION">Privoxy</span> is configured to use socks4a, one
- can use <span class=
- "QUOTE">"http://www.example.org.foobar.exit/"</span> to access
- the host <span class="QUOTE">"www.example.org"</span> through the
- <b class="COMMAND">Tor</b> exit node <span class=
- "QUOTE">"foobar"</span>.</p>
-
- <p>As the HTTP client isn't aware of this notation, it treats the
- whole string <span class=
- "QUOTE">"www.example.org.foobar.exit"</span> as host and uses it
- for the <span class="QUOTE">"Host"</span> and <span class=
- "QUOTE">"Referer"</span> headers. From the server's point of view
- the resulting headers are invalid and can cause problems.</p>
-
- <p>An invalid <span class="QUOTE">"Referer"</span> header can
- trigger <span class="QUOTE">"hot-linking"</span> protections, an
- invalid <span class="QUOTE">"Host"</span> header will make it
- impossible for the server to find the right vhost (several
- domains hosted on the same IP address).</p>
+ </td>
+ </tr>
+ </table>
- <p>This client-header filter removes the <span class=
- "QUOTE">"foo.exit"</span> part in those headers to prevent the
- mentioned problems. Note that it only modifies the HTTP headers,
- it doesn't make it impossible for the server to detect your
- <b class="COMMAND">Tor</b> exit node based on the IP address the
- request is coming from.</p>
- </dd>
- </dl>
+ <p>
+ The <tt class="LITERAL">x</tt> option in this job turns on extended
+ syntax, and allows for e.g. the liberal use of (non-interpreted!)
+ whitespace for nicer formatting.
+ </p>
+ <p>
+ You get the idea?
+ </p>
</div>
- </div>
-
- <div class="SECT2">
- <h2 class="SECT2"><a name="EXTERNAL-FILTER-SYNTAX" id=
- "EXTERNAL-FILTER-SYNTAX">9.3. External filter syntax</a></h2>
-
- <p>External filters are scripts or programs that can modify the content
- in case common <tt class="LITERAL"><a href=
- "actions-file.html#FILTER">filters</a></tt> aren't powerful enough.</p>
-
- <p>External filters can be written in any language the platform
- <span class="APPLICATION">Privoxy</span> runs on supports.</p>
-
- <p>They are controlled with the <tt class="LITERAL"><a href=
- "actions-file.html#EXTERNAL-FILTER">external-filter</a></tt> action and
- have to be defined in the <tt class="LITERAL"><a href=
- "config.html#FILTERFILE">filterfile</a></tt> first.</p>
-
- <p>The header looks like any other filter, but instead of pcrs jobs,
- external filters contain a single job which can be a program or a shell
- script (which may call other scripts or programs).</p>
-
- <p>External filters read the content from STDIN and write the rewritten
- content to STDOUT. The environment variables PRIVOXY_URL, PRIVOXY_PATH,
- PRIVOXY_HOST, PRIVOXY_ORIGIN, PRIVOXY_LISTEN_ADDRESS can be used to get
- some details about the client request.</p>
-
- <p><span class="APPLICATION">Privoxy</span> will temporary store the
- content to filter in the <tt class="LITERAL"><a href=
- "config.html#TEMPORARY-DIRECTORY">temporary-directory</a></tt>.</p>
-
- <table border="0" bgcolor="#E0E0E0" width="100%">
- <tr>
- <td>
- <pre class="SCREEN">
+ <div class="SECT2">
+ <h2 class="SECT2">
+ <a name="PREDEFINED-FILTERS">9.2. The Pre-defined Filters</a>
+ </h2>
+ <p>
+ The distribution <tt class="FILENAME">default.filter</tt> file
+ contains a selection of pre-defined filters for your convenience:
+ </p>
+ <div class="VARIABLELIST">
+ <dl>
+ <dt>
+ <span class="emphasis"><i class=
+ "EMPHASIS">js-annoyances</i></span>
+ </dt>
+ <dd>
+ <p>
+ The purpose of this filter is to get rid of particularly
+ annoying JavaScript abuse. To that end, it
+ </p>
+ <ul>
+ <li>
+ <p>
+ replaces JavaScript references to the browser's referrer
+ information with the string "Not Your Business!". This
+ compliments the <tt class="LITERAL"><a href=
+ "actions-file.html#HIDE-REFERRER">hide-referrer</a></tt>
+ action on the content level.
+ </p>
+ </li>
+ <li>
+ <p>
+ removes the bindings to the DOM's <a href=
+ "http://www.w3.org/TR/2000/REC-DOM-Level-2-Events-20001113/events.html#Events-eventgroupings-htmlevents"
+ target="_top">unload event</a> which we feel has no
+ right to exist and is responsible for most <span class=
+ "QUOTE">"exit consoles"</span>, i.e. nasty windows that
+ pop up when you close another one.
+ </p>
+ </li>
+ <li>
+ <p>
+ removes code that causes new windows to be opened with
+ undesired properties, such as being full-screen,
+ non-resizeable, without location, status or menu bar etc.
+ </p>
+ </li>
+ </ul>
+
+ <p>
+ Use with caution. This is an aggressive filter, and can break
+ sites that rely heavily on JavaScript.
+ </p>
+ </dd>
+ <dt>
+ <span class="emphasis"><i class="EMPHASIS">js-events</i></span>
+ </dt>
+ <dd>
+ <p>
+ This is a very radical measure. It removes virtually all
+ JavaScript event bindings, which means that scripts can not
+ react to user actions such as mouse movements or clicks,
+ window resizing etc, anymore. Use with caution!
+ </p>
+ <p>
+ We <span class="emphasis"><i class="EMPHASIS">strongly
+ discourage</i></span> using this filter as a default since it
+ breaks many legitimate scripts. It is meant for use only on
+ extra-nasty sites (should you really need to go there).
+ </p>
+ </dd>
+ <dt>
+ <span class="emphasis"><i class=
+ "EMPHASIS">html-annoyances</i></span>
+ </dt>
+ <dd>
+ <p>
+ This filter will undo many common instances of HTML based
+ abuse.
+ </p>
+ <p>
+ The <tt class="LITERAL">BLINK</tt> and <tt class=
+ "LITERAL">MARQUEE</tt> tags are neutralized (yeah baby!), and
+ browser windows will be created as resizeable (as of course
+ they should be!), and will have location, scroll and menu
+ bars -- even if specified otherwise.
+ </p>
+ </dd>
+ <dt>
+ <span class="emphasis"><i class=
+ "EMPHASIS">content-cookies</i></span>
+ </dt>
+ <dd>
+ <p>
+ Most cookies are set in the HTTP dialog, where they can be
+ intercepted by the <tt class="LITERAL"><a href=
+ "actions-file.html#CRUNCH-INCOMING-COOKIES">crunch-incoming-cookies</a></tt>
+ and <tt class="LITERAL"><a href=
+ "actions-file.html#CRUNCH-OUTGOING-COOKIES">crunch-outgoing-cookies</a></tt>
+ actions. But web sites increasingly make use of HTML meta
+ tags and JavaScript to sneak cookies to the browser on the
+ content level.
+ </p>
+ <p>
+ This filter disables most HTML and JavaScript code that reads
+ or sets cookies. It cannot detect all clever uses of these
+ types of code, so it should not be relied on as an absolute
+ fix. Use it wherever you would also use the cookie crunch
+ actions.
+ </p>
+ </dd>
+ <dt>
+ <span class="emphasis"><i class=
+ "EMPHASIS">refresh-tags</i></span>
+ </dt>
+ <dd>
+ <p>
+ Disable any refresh tags if the interval is greater than nine
+ seconds (so that redirections done via refresh tags are not
+ destroyed). This is useful for dial-on-demand setups, or for
+ those who find this HTML feature annoying.
+ </p>
+ </dd>
+ <dt>
+ <span class="emphasis"><i class=
+ "EMPHASIS">unsolicited-popups</i></span>
+ </dt>
+ <dd>
+ <p>
+ This filter attempts to prevent only <span class=
+ "QUOTE">"unsolicited"</span> pop-up windows from opening, yet
+ still allow pop-up windows that the user has explicitly
+ chosen to open. It was added in version 3.0.1, as an
+ improvement over earlier such filters.
+ </p>
+ <p>
+ Technical note: The filter works by redefining the
+ window.open JavaScript function to a dummy function, <tt
+ class="LITERAL">PrivoxyWindowOpen()</tt>, during the loading
+ and rendering phase of each HTML page access, and restoring
+ the function afterward.
+ </p>
+ <p>
+ This is recommended only for browsers that cannot perform
+ this function reliably themselves. And be aware that some
+ sites require such windows in order to function normally. Use
+ with caution.
+ </p>
+ </dd>
+ <dt>
+ <span class="emphasis"><i class=
+ "EMPHASIS">all-popups</i></span>
+ </dt>
+ <dd>
+ <p>
+ Attempt to prevent <span class="emphasis"><i class=
+ "EMPHASIS">all</i></span> pop-up windows from opening. Note
+ this should be used with even more discretion than the above,
+ since it is more likely to break some sites that require
+ pop-ups for normal usage. Use with caution.
+ </p>
+ </dd>
+ <dt>
+ <span class="emphasis"><i class=
+ "EMPHASIS">img-reorder</i></span>
+ </dt>
+ <dd>
+ <p>
+ This is a helper filter that has no value if used alone. It
+ makes the <tt class="LITERAL">banners-by-size</tt> and <tt
+ class="LITERAL">banners-by-link</tt> (see below) filters more
+ effective and should be enabled together with them.
+ </p>
+ </dd>
+ <dt>
+ <span class="emphasis"><i class=
+ "EMPHASIS">banners-by-size</i></span>
+ </dt>
+ <dd>
+ <p>
+ This filter removes image tags purely based on what size they
+ are. Fortunately for us, many ads and banner images tend to
+ conform to certain standardized sizes, which makes this
+ filter quite effective for ad stripping purposes.
+ </p>
+ <p>
+ Occasionally this filter will cause false positives on images
+ that are not ads, but just happen to be of one of the
+ standard banner sizes.
+ </p>
+ <p>
+ Recommended only for those who require extreme ad blocking.
+ The default block rules should catch 95+% of all ads <span
+ class="emphasis"><i class="EMPHASIS">without</i></span> this
+ filter enabled.
+ </p>
+ </dd>
+ <dt>
+ <span class="emphasis"><i class=
+ "EMPHASIS">banners-by-link</i></span>
+ </dt>
+ <dd>
+ <p>
+ This is an experimental filter that attempts to kill any
+ banners if their URLs seem to point to known or suspected
+ click trackers. It is currently not of much value and is not
+ recommended for use by default.
+ </p>
+ </dd>
+ <dt>
+ <span class="emphasis"><i class="EMPHASIS">webbugs</i></span>
+ </dt>
+ <dd>
+ <p>
+ Webbugs are small, invisible images (technically 1X1 GIF
+ images), that are used to track users across websites, and
+ collect information on them. As an HTML page is loaded by the
+ browser, an embedded image tag causes the browser to contact
+ a third-party site, disclosing the tracking information
+ through the requested URL and/or cookies for that third-party
+ domain, without the user ever becoming aware of the
+ interaction with the third-party site. HTML-ized spam also
+ uses a similar technique to verify email addresses.
+ </p>
+ <p>
+ This filter removes the HTML code that loads such <span
+ class="QUOTE">"webbugs"</span>.
+ </p>
+ </dd>
+ <dt>
+ <span class="emphasis"><i class=
+ "EMPHASIS">tiny-textforms</i></span>
+ </dt>
+ <dd>
+ <p>
+ A rather special-purpose filter that can be used to enlarge
+ textareas (those multi-line text boxes in web forms) and turn
+ off hard word wrap in them. It was written for the
+ sourceforge.net tracker system where such boxes are a
+ nuisance, but it can be handy on other sites, too.
+ </p>
+ <p>
+ It is not recommended to use this filter as a default.
+ </p>
+ </dd>
+ <dt>
+ <span class="emphasis"><i class=
+ "EMPHASIS">jumping-windows</i></span>
+ </dt>
+ <dd>
+ <p>
+ Many consider windows that move, or resize themselves to be
+ abusive. This filter neutralizes the related JavaScript code.
+ Note that some sites might not display or behave as intended
+ when using this filter. Use with caution.
+ </p>
+ </dd>
+ <dt>
+ <span class="emphasis"><i class=
+ "EMPHASIS">frameset-borders</i></span>
+ </dt>
+ <dd>
+ <p>
+ Some web designers seem to assume that everyone in the world
+ will view their web sites using the same browser brand and
+ version, screen resolution etc, because only that assumption
+ could explain why they'd use static frame sizes, yet prevent
+ their frames from being resized by the user, should they be
+ too small to show their whole content.
+ </p>
+ <p>
+ This filter removes the related HTML code. It should only be
+ applied to sites which need it.
+ </p>
+ </dd>
+ <dt>
+ <span class="emphasis"><i class=
+ "EMPHASIS">demoronizer</i></span>
+ </dt>
+ <dd>
+ <p>
+ Many Microsoft products that generate HTML use non-standard
+ extensions (read: violations) of the ISO 8859-1 aka Latin-1
+ character set. This can cause those HTML documents to display
+ with errors on standard-compliant platforms.
+ </p>
+ <p>
+ This filter translates the MS-only characters into Latin-1
+ equivalents. It is not necessary when using MS products, and
+ will cause corruption of all documents that use 8-bit
+ character sets other than Latin-1. It's mostly worthwhile for
+ Europeans on non-MS platforms, if weird garbage characters
+ sometimes appear on some pages, or user agents that don't
+ correct for this on the fly.
+ </p>
+ </dd>
+ <dt>
+ <span class="emphasis"><i class=
+ "EMPHASIS">shockwave-flash</i></span>
+ </dt>
+ <dd>
+ <p>
+ A filter for shockwave haters. As the name suggests, this
+ filter strips code out of web pages that is used to embed
+ shockwave flash objects.
+ </p>
+ <p>
+ </p>
+ </dd>
+ <dt>
+ <span class="emphasis"><i class=
+ "EMPHASIS">quicktime-kioskmode</i></span>
+ </dt>
+ <dd>
+ <p>
+ Change HTML code that embeds Quicktime objects so that
+ kioskmode, which prevents saving, is disabled.
+ </p>
+ </dd>
+ <dt>
+ <span class="emphasis"><i class="EMPHASIS">fun</i></span>
+ </dt>
+ <dd>
+ <p>
+ Text replacements for subversive browsing fun. Make fun of
+ your favorite Monopolist or play buzzword bingo.
+ </p>
+ </dd>
+ <dt>
+ <span class="emphasis"><i class=
+ "EMPHASIS">crude-parental</i></span>
+ </dt>
+ <dd>
+ <p>
+ A demonstration-only filter that shows how <span class=
+ "APPLICATION">Privoxy</span> can be used to delete web
+ content on a keyword basis.
+ </p>
+ </dd>
+ <dt>
+ <span class="emphasis"><i class=
+ "EMPHASIS">ie-exploits</i></span>
+ </dt>
+ <dd>
+ <p>
+ An experimental collection of text replacements to disable
+ malicious HTML and JavaScript code that exploits known
+ security holes in Internet Explorer.
+ </p>
+ <p>
+ Presently, it only protects against Nimda and a cross-site
+ scripting bug, and would need active maintenance to provide
+ more substantial protection.
+ </p>
+ </dd>
+ <dt>
+ <span class="emphasis"><i class=
+ "EMPHASIS">site-specifics</i></span>
+ </dt>
+ <dd>
+ <p>
+ Some web sites have very specific problems, the cure for
+ which doesn't apply anywhere else, or could even cause damage
+ on other sites.
+ </p>
+ <p>
+ This is a collection of such site-specific cures which should
+ only be applied to the sites they were intended for, which is
+ what the supplied <tt class="FILENAME">default.action</tt>
+ file does. Users shouldn't need to change anything regarding
+ this filter.
+ </p>
+ </dd>
+ <dt>
+ <span class="emphasis"><i class="EMPHASIS">google</i></span>
+ </dt>
+ <dd>
+ <p>
+ A CSS based block for Google text ads. Also removes a width
+ limitation and the toolbar advertisement.
+ </p>
+ </dd>
+ <dt>
+ <span class="emphasis"><i class="EMPHASIS">yahoo</i></span>
+ </dt>
+ <dd>
+ <p>
+ Another CSS based block, this time for Yahoo text ads. And
+ removes a width limitation as well.
+ </p>
+ </dd>
+ <dt>
+ <span class="emphasis"><i class="EMPHASIS">msn</i></span>
+ </dt>
+ <dd>
+ <p>
+ Another CSS based block, this time for MSN text ads. And
+ removes tracking URLs, as well as a width limitation.
+ </p>
+ </dd>
+ <dt>
+ <span class="emphasis"><i class="EMPHASIS">blogspot</i></span>
+ </dt>
+ <dd>
+ <p>
+ Cleans up some Blogspot blogs. Read the fine print before
+ using this one!
+ </p>
+ <p>
+ This filter also intentionally removes some navigation stuff
+ and sets the page width to 100%. As a result, some rounded
+ <span class="QUOTE">"corners"</span> would appear to early or
+ not at all and as fixing this would require a browser that
+ understands background-size (CSS3), they are removed instead.
+ </p>
+ </dd>
+ <dt>
+ <span class="emphasis"><i class=
+ "EMPHASIS">xml-to-html</i></span>
+ </dt>
+ <dd>
+ <p>
+ Server-header filter to change the Content-Type from xml to
+ html.
+ </p>
+ </dd>
+ <dt>
+ <span class="emphasis"><i class=
+ "EMPHASIS">html-to-xml</i></span>
+ </dt>
+ <dd>
+ <p>
+ Server-header filter to change the Content-Type from html to
+ xml.
+ </p>
+ </dd>
+ <dt>
+ <span class="emphasis"><i class="EMPHASIS">no-ping</i></span>
+ </dt>
+ <dd>
+ <p>
+ Removes the non-standard <tt class="LITERAL">ping</tt>
+ attribute from anchor and area HTML tags.
+ </p>
+ </dd>
+ <dt>
+ <span class="emphasis"><i class=
+ "EMPHASIS">hide-tor-exit-notation</i></span>
+ </dt>
+ <dd>
+ <p>
+ Client-header filter to remove the <b class="COMMAND">Tor</b>
+ exit node notation found in Host and Referer headers.
+ </p>
+ <p>
+ If <span class="APPLICATION">Privoxy</span> and <b class=
+ "COMMAND">Tor</b> are chained and <span class=
+ "APPLICATION">Privoxy</span> is configured to use socks4a,
+ one can use <span class=
+ "QUOTE">"http://www.example.org.foobar.exit/"</span> to
+ access the host <span class="QUOTE">"www.example.org"</span>
+ through the <b class="COMMAND">Tor</b> exit node <span class=
+ "QUOTE">"foobar"</span>.
+ </p>
+ <p>
+ As the HTTP client isn't aware of this notation, it treats
+ the whole string <span class=
+ "QUOTE">"www.example.org.foobar.exit"</span> as host and uses
+ it for the <span class="QUOTE">"Host"</span> and <span class=
+ "QUOTE">"Referer"</span> headers. From the server's point of
+ view the resulting headers are invalid and can cause
+ problems.
+ </p>
+ <p>
+ An invalid <span class="QUOTE">"Referer"</span> header can
+ trigger <span class="QUOTE">"hot-linking"</span> protections,
+ an invalid <span class="QUOTE">"Host"</span> header will make
+ it impossible for the server to find the right vhost (several
+ domains hosted on the same IP address).
+ </p>
+ <p>
+ This client-header filter removes the <span class=
+ "QUOTE">"foo.exit"</span> part in those headers to prevent
+ the mentioned problems. Note that it only modifies the HTTP
+ headers, it doesn't make it impossible for the server to
+ detect your <b class="COMMAND">Tor</b> exit node based on the
+ IP address the request is coming from.
+ </p>
+ </dd>
+ </dl>
+ </div>
+ </div>
+ <div class="SECT2">
+ <h2 class="SECT2">
+ <a name="EXTERNAL-FILTER-SYNTAX">9.3. External filter syntax</a>
+ </h2>
+ <p>
+ External filters are scripts or programs that can modify the
+ content in case common <tt class="LITERAL"><a href=
+ "actions-file.html#FILTER">filters</a></tt> aren't powerful enough.
+ </p>
+ <p>
+ External filters can be written in any language the platform <span
+ class="APPLICATION">Privoxy</span> runs on supports.
+ </p>
+ <p>
+ They are controlled with the <tt class="LITERAL"><a href=
+ "actions-file.html#EXTERNAL-FILTER">external-filter</a></tt> action
+ and have to be defined in the <tt class="LITERAL"><a href=
+ "config.html#FILTERFILE">filterfile</a></tt> first.
+ </p>
+ <p>
+ The header looks like any other filter, but instead of pcrs jobs,
+ external filters contain a single job which can be a program or a
+ shell script (which may call other scripts or programs).
+ </p>
+ <p>
+ External filters read the content from STDIN and write the
+ rewritten content to STDOUT. The environment variables PRIVOXY_URL,
+ PRIVOXY_PATH, PRIVOXY_HOST, PRIVOXY_ORIGIN, PRIVOXY_LISTEN_ADDRESS
+ can be used to get some details about the client request.
+ </p>
+ <p>
+ <span class="APPLICATION">Privoxy</span> will temporary store the
+ content to filter in the <tt class="LITERAL"><a href=
+ "config.html#TEMPORARY-DIRECTORY">temporary-directory</a></tt>.
+ </p>
+ <p>
+ </p>
+ <table border="0" bgcolor="#E0E0E0" width="100%">
+ <tr>
+ <td>
+<pre class="SCREEN">
EXTERNAL-FILTER: cat Pointless example filter that doesn't actually modify the content
/bin/cat
EXTERNAL-FILTER: citation-needed Adds a "[citation needed]" tag to an image. The coordinates may need adjustment.
/usr/local/bin/convert - -pointsize 16 -fill white -annotate +17+418 "[citation needed]" -
</pre>
- </td>
- </tr>
- </table>
-
- <div class="WARNING">
- <table class="WARNING" border="1" width="100%">
- <tr>
- <td align="center"><b>Warning</b></td>
- </tr>
-
- <tr>
- <td align="left">
- <p>Currently external filters are executed with <span class=
- "APPLICATION">Privoxy</span>'s privileges! Only use external
- filters you understand and trust.</p>
</td>
</tr>
</table>
- </div>
- <p>External filters are experimental and the syntax may change in the
- future.</p>
+ <div class="WARNING">
+ <table class="WARNING" border="1" width="100%">
+ <tr>
+ <td align="CENTER">
+ <b>Warning</b>
+ </td>
+ </tr>
+ <tr>
+ <td align="LEFT">
+ <p>
+ Currently external filters are executed with <span class=
+ "APPLICATION">Privoxy</span>'s privileges! Only use
+ external filters you understand and trust.
+ </p>
+ </td>
+ </tr>
+ </table>
+ </div>
+ <p>
+ External filters are experimental and the syntax may change in the
+ future.
+ </p>
+ </div>
</div>
- </div>
-
- <div class="NAVFOOTER">
- <hr align="left" width="100%">
-
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-
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+ <div class="NAVFOOTER">
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+ cellpadding="0" cellspacing="0">
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+ <td width="33%" align="left" valign="top">
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+ </td>
+ <td width="34%" align="center" valign="top">
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+ </td>
+ </tr>
+ <tr>
+ <td width="33%" align="left" valign="top">
+ Actions Files
+ </td>
+ <td width="34%" align="center" valign="top">
+
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+ </td>
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+ </div>
+ </body>
</html>
+
projects / privoxy.git / blobdiff