-<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN""http://www.w3.org/TR/html4/loose.dtd">
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-><HEAD
-><TITLE
->Filter Files</TITLE
-><META
-NAME="GENERATOR"
-CONTENT="Modular DocBook HTML Stylesheet Version 1.79"><LINK
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-CLASS="SECT1"
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-COLSPAN="3"
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->Privoxy 3.0.7 User Manual</TH
-></TR
-><TR
-><TD
-WIDTH="10%"
-ALIGN="left"
-VALIGN="bottom"
-><A
-HREF="actions-file.html"
-ACCESSKEY="P"
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-><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 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, and</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
-> 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 will be found 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
-> Command 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
-> Content filtering works on any text-based document type, including
- HTML, JavaScript, CSS etc. (all <TT
-CLASS="LITERAL"
->text/*</TT
->
- MIME types, <SPAN
-CLASS="emphasis"
-><I
-CLASS="EMPHASIS"
->except</I
-></SPAN
-> <TT
-CLASS="LITERAL"
->text/plain</TT
->).
- 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
-> <TABLE
-BORDER="0"
-BGCOLOR="#E0E0E0"
-WIDTH="100%"
-><TR
-><TD
-><PRE
-CLASS="SCREEN"
->FILTER: foo Replace all "foo" with "bar"</PRE
-></TD
-></TR
-></TABLE
-></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. Most
- notably, the non-standard option letter <TT
-CLASS="LITERAL"
->U</TT
-> is supported,
- which turns the default to ungreedy matching.</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="AEN4629"
->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
-> <TABLE
-BORDER="0"
-BGCOLOR="#E0E0E0"
-WIDTH="100%"
-><TR
-><TD
-><PRE
-CLASS="SCREEN"
->s/foo/bar/</PRE
-></TD
-></TR
-></TABLE
-></P
-><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
-> <TABLE
-BORDER="0"
-BGCOLOR="#E0E0E0"
-WIDTH="100%"
-><TR
-><TD
-><PRE
-CLASS="SCREEN"
->s/foo/bar/g</PRE
-></TD
-></TR
-></TABLE
-></P
-><P
-> Our complete filter now looks like this:</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
-></P
-><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
-> <TABLE
-BORDER="0"
-BGCOLOR="#E0E0E0"
-WIDTH="100%"
-><TR
-><TD
-><PRE
-CLASS="SCREEN"
->FILTER: js-annoyances Get rid of particularly annoying JavaScript abuse
+<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"
+"http://www.w3.org/TR/html4/loose.dtd">
+
+<html>
+<head>
+ <title>Filter Files</title>
+ <meta name="GENERATOR" content=
+ "Modular DocBook HTML Stylesheet Version 1.79">
+ <link rel="HOME" title="Privoxy 3.0.21 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=us-ascii">
+ <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>
+ <th colspan="3" align="center">Privoxy 3.0.21 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>
+ <hr align="left" width="100%">
+ </div>
+
+ <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
+ 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>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. Most notably, the non-standard option letter <tt class=
+ "LITERAL">U</tt> is supported, which turns the default to ungreedy
+ matching.</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="AEN5097" id="AEN5097">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%">
+ <tr>
+ <td>
+ <pre class="SCREEN">
+s/foo/bar/
+</pre>
+ </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>
+
+ <table border="0" bgcolor="#E0E0E0" width="100%">
+ <tr>
+ <td>
+ <pre class="SCREEN">
+s/foo/bar/g
+</pre>
+ </td>
+ </tr>
+ </table>
+
+ <p>Our complete filter now looks like this:</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>
+
+ <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>
+
+ <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
-><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
-> <TABLE
-BORDER="0"
-BGCOLOR="#E0E0E0"
-WIDTH="100%"
-><TR
-><TD
-><PRE
-CLASS="SCREEN"
-># The status bar is for displaying link targets, not pointless blahblah
+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>
+
+ <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
-><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
-> <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/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>
+
+ <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
-><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
-> <TABLE
-BORDER="0"
-BGCOLOR="#E0E0E0"
-WIDTH="100%"
-><TR
-><TD
-><PRE
-CLASS="SCREEN"
->FILTER: fun Fun text replacements
+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>
+
+ <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
-><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
-> <TABLE
-BORDER="0"
-BGCOLOR="#E0E0E0"
-WIDTH="100%"
-><TR
-><TD
-><PRE
-CLASS="SCREEN"
-># Buzzword Bingo (example for extended regex syntax)
+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>
+
+ <table border="0" bgcolor="#E0E0E0" width="100%">
+ <tr>
+ <td>
+ <pre class="SCREEN">
+# Buzzword Bingo (example for extended regex syntax)
#
s* industry[ -]leading \
| cutting[ -]edge \
| unmatched \
| unparalleled \
| unrivalled \
-*<font color="red"><b>BINGO!</b></font> \
-*igx</PRE
-></TD
-></TR
-></TABLE
-></P
-><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"
->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
-><P
-></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
-></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
-><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
-><DIV
-CLASS="NAVFOOTER"
-><HR
-ALIGN="LEFT"
-WIDTH="100%"><TABLE
-SUMMARY="Footer navigation table"
-WIDTH="100%"
-BORDER="0"
-CELLPADDING="0"
-CELLSPACING="0"
-><TR
-><TD
-WIDTH="33%"
-ALIGN="left"
-VALIGN="top"
-><A
-HREF="actions-file.html"
-ACCESSKEY="P"
->Prev</A
-></TD
-><TD
-WIDTH="34%"
-ALIGN="center"
-VALIGN="top"
-><A
-HREF="index.html"
-ACCESSKEY="H"
->Home</A
-></TD
-><TD
-WIDTH="33%"
-ALIGN="right"
-VALIGN="top"
-><A
-HREF="templates.html"
-ACCESSKEY="N"
->Next</A
-></TD
-></TR
-><TR
-><TD
-WIDTH="33%"
-ALIGN="left"
-VALIGN="top"
->Actions Files</TD
-><TD
-WIDTH="34%"
-ALIGN="center"
-VALIGN="top"
-> </TD
-><TD
-WIDTH="33%"
-ALIGN="right"
-VALIGN="top"
->Privoxy's Template Files</TD
-></TR
-></TABLE
-></DIV
-></BODY
-></HTML
->
\ No newline at end of file
+*<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>
+
+ <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>
+
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+
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+
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projects / privoxy.git / blobdiff