1 <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"
2 "http://www.w3.org/TR/html4/loose.dtd">
6 <title>Actions Files</title>
7 <meta name="GENERATOR" content=
8 "Modular DocBook HTML Stylesheet Version 1.79">
9 <link rel="HOME" title="Privoxy 3.0.20 User Manual" href="index.html">
10 <link rel="PREVIOUS" title="The Main Configuration File" href=
12 <link rel="NEXT" title="Filter Files" href="filter-file.html">
13 <link rel="STYLESHEET" type="text/css" href="../p_doc.css">
14 <meta http-equiv="Content-Type" content="text/html; charset=us-ascii">
15 <link rel="STYLESHEET" type="text/css" href="p_doc.css">
16 <style type="text/css">
18 background-color: #EEEEEE;
21 :link { color: #0000FF }
22 :visited { color: #840084 }
23 :active { color: #0000FF }
24 td.c6 {font-weight: bold}
25 tt.c5 {font-style: italic}
26 table.c4 {background-color: #E0E0E0}
27 p.c3 {font-weight: bold}
28 span.c2 {font-style: italic}
29 hr.c1 {text-align: left}
34 <div class="NAVHEADER">
35 <table summary="Header navigation table" width="100%" border="0"
36 cellpadding="0" cellspacing="0">
38 <th colspan="3" align="center">Privoxy 3.0.20 User Manual</th>
42 <td width="10%" align="left" valign="bottom"><a href="config.html"
43 accesskey="P">Prev</a></td>
45 <td width="80%" align="center" valign="bottom"></td>
47 <td width="10%" align="right" valign="bottom"><a href=
48 "filter-file.html" accesskey="N">Next</a></td>
51 <hr class="c1" width="100%">
55 <h1 class="SECT1"><a name="ACTIONS-FILE" id="ACTIONS-FILE">8. Actions
58 <p>The actions files are used to define what <span class=
59 "emphasis EMPHASIS c2">actions</span> <span class=
60 "APPLICATION">Privoxy</span> takes for which URLs, and thus determines
61 how ad images, cookies and various other aspects of HTTP content and
62 transactions are handled, and on which sites (or even parts thereof).
63 There are a number of such actions, with a wide range of functionality.
64 Each action does something a little different. These actions give us a
65 veritable arsenal of tools with which to exert our control, preferences
66 and independence. Actions can be combined so that their effects are
67 aggregated when applied against a given set of URLs.</p>
69 <p>There are three action files included with <span class=
70 "APPLICATION">Privoxy</span> with differing purposes:</p>
74 <p><tt class="FILENAME">match-all.action</tt> - is used to define
75 which <span class="QUOTE">"actions"</span> relating to
76 banner-blocking, images, pop-ups, content modification, cookie
77 handling etc should be applied by default. It should be the first
78 actions file loaded</p>
82 <p><tt class="FILENAME">default.action</tt> - defines many exceptions
83 (both positive and negative) from the default set of actions that's
84 configured in <tt class="FILENAME">match-all.action</tt>. It is a set
85 of rules that should work reasonably well as-is for most users. This
86 file is only supposed to be edited by the developers. It should be
87 the second actions file loaded.</p>
91 <p><tt class="FILENAME">user.action</tt> - is intended to be for
92 local site preferences and exceptions. As an example, if your ISP or
93 your bank has specific requirements, and need special handling, this
94 kind of thing should go here. This file will not be upgraded.</p>
98 <p><span class="GUIBUTTON">Edit</span> <span class="GUIBUTTON">Set to
99 Cautious</span> <span class="GUIBUTTON">Set to Medium</span>
100 <span class="GUIBUTTON">Set to Advanced</span></p>
102 <p>These have increasing levels of aggressiveness <span class=
103 "emphasis EMPHASIS c2">and have no influence on your browsing unless
104 you select them explicitly in the editor</span>. A default
105 installation should be pre-set to <tt class="LITERAL">Cautious</tt>.
106 New users should try this for a while before adjusting the settings
107 to more aggressive levels. The more aggressive the settings, then the
108 more likelihood there is of problems such as sites not working as
111 <p>The <span class="GUIBUTTON">Edit</span> button allows you to turn
112 each action on/off individually for fine-tuning. The <span class=
113 "GUIBUTTON">Cautious</span> button changes the actions list to
114 low/safe settings which will activate ad blocking and a minimal set
115 of <span class="APPLICATION">Privoxy</span>'s features, and
116 subsequently there will be less of a chance for accidental problems.
117 The <span class="GUIBUTTON">Medium</span> button sets the list to a
118 medium level of other features and a low level set of privacy
119 features. The <span class="GUIBUTTON">Advanced</span> button sets the
120 list to a high level of ad blocking and medium level of privacy. See
121 the chart below. The latter three buttons over-ride any changes via
122 with the <span class="GUIBUTTON">Edit</span> button. More fine-tuning
123 can be done in the lower sections of this internal page.</p>
125 <p>While the actions file editor allows to enable these settings in
126 all actions files, they are only supposed to be enabled in the first
127 one to make sure you don't unintentionally overrule earlier
130 <p>The default profiles, and their associated actions, as pre-defined
131 in <tt class="FILENAME">default.action</tt> are:</p>
134 <a name="AEN2799" id="AEN2799"></a>
136 <p class="c3">Table 1. Default Configurations</p>
138 <table border="1" frame="border" rules="all" class="CALSTABLE">
139 <col width="1*" title="C1">
140 <col width="1*" title="C2">
141 <col width="1*" title="C3">
142 <col width="1*" title="C4">
158 <td>Ad-blocking Aggressiveness</td>
168 <td>Ad-filtering by size</td>
178 <td>Ad-filtering by link</td>
188 <td>Pop-up killing</td>
198 <td>Privacy Features</td>
208 <td>Cookie handling</td>
212 <td>session-only</td>
218 <td>Referer forging</td>
228 <td>GIF de-animation</td>
238 <td>Fast redirects</td>
258 <td>JavaScript taming</td>
268 <td>Web-bug killing</td>
278 <td>Image tag reordering</td>
292 <p>The list of actions files to be used are defined in the main
293 configuration file, and are processed in the order they are defined (e.g.
294 <tt class="FILENAME">default.action</tt> is typically processed before
295 <tt class="FILENAME">user.action</tt>). The content of these can all be
296 viewed and edited from <a href="http://config.privoxy.org/show-status"
297 target="_top">http://config.privoxy.org/show-status</a>. The over-riding
298 principle when applying actions, is that the last action that matches a
299 given URL wins. The broadest, most general rules go first (defined in
300 <tt class="FILENAME">default.action</tt>), followed by any exceptions
301 (typically also in <tt class="FILENAME">default.action</tt>), which are
302 then followed lastly by any local preferences (typically in <span class=
303 "emphasis EMPHASIS c2">user</span><tt class="FILENAME">.action</tt>).
304 Generally, <tt class="FILENAME">user.action</tt> has the last word.</p>
306 <p>An actions file typically has multiple sections. If you want to use
307 <span class="QUOTE">"aliases"</span> in an actions file, you have to
308 place the (optional) <a href="actions-file.html#ALIASES">alias
309 section</a> at the top of that file. Then comes the default set of rules
310 which will apply universally to all sites and pages (be <span class=
311 "emphasis EMPHASIS c2">very careful</span> with using such a universal
312 set in <tt class="FILENAME">user.action</tt> or any other actions file
313 after <tt class="FILENAME">default.action</tt>, because it will override
314 the result from consulting any previous file). And then below that,
315 exceptions to the defined universal policies. You can regard <tt class=
316 "FILENAME">user.action</tt> as an appendix to <tt class=
317 "FILENAME">default.action</tt>, with the advantage that it is a separate
318 file, which makes preserving your personal settings across <span class=
319 "APPLICATION">Privoxy</span> upgrades easier.</p>
321 <p>Actions can be used to block anything you want, including ads,
322 banners, or just some obnoxious URL whose content you would rather not
323 see. Cookies can be accepted or rejected, or accepted only during the
324 current browser session (i.e. not written to disk), content can be
325 modified, some JavaScripts tamed, user-tracking fooled, and much more.
326 See below for a <a href="actions-file.html#ACTIONS">complete list of
330 <h2 class="SECT2"><a name="AEN2898" id="AEN2898">8.1. Finding the Right
333 <p>Note that some <a href="actions-file.html#ACTIONS">actions</a>, like
334 cookie suppression or script disabling, may render some sites unusable
335 that rely on these techniques to work properly. Finding the right mix
336 of actions is not always easy and certainly a matter of personal taste.
337 And, things can always change, requiring refinements in the
338 configuration. In general, it can be said that the more <span class=
339 "QUOTE">"aggressive"</span> your default settings (in the top section
340 of the actions file) are, the more exceptions for <span class=
341 "QUOTE">"trusted"</span> sites you will have to make later. If, for
342 example, you want to crunch all cookies per default, you'll have to
343 make exceptions from that rule for sites that you regularly use and
344 that require cookies for actually useful purposes, like maybe your
345 bank, favorite shop, or newspaper.</p>
347 <p>We have tried to provide you with reasonable rules to start from in
348 the distribution actions files. But there is no general rule of thumb
349 on these things. There just are too many variables, and sites are
350 constantly changing. Sooner or later you will want to change the rules
351 (and read this chapter again :).</p>
355 <h2 class="SECT2"><a name="AEN2905" id="AEN2905">8.2. How to
358 <p>The easiest way to edit the actions files is with a browser by using
359 our browser-based editor, which can be reached from <a href=
360 "http://config.privoxy.org/show-status" target=
361 "_top">http://config.privoxy.org/show-status</a>. Note: the config file
363 "config.html#ENABLE-EDIT-ACTIONS">enable-edit-actions</a> must be
364 enabled for this to work. The editor allows both fine-grained control
365 over every single feature on a per-URL basis, and easy choosing from
366 wholesale sets of defaults like <span class="QUOTE">"Cautious"</span>,
367 <span class="QUOTE">"Medium"</span> or <span class=
368 "QUOTE">"Advanced"</span>. Warning: the <span class=
369 "QUOTE">"Advanced"</span> setting is more aggressive, and will be more
370 likely to cause problems for some sites. Experienced users only!</p>
372 <p>If you prefer plain text editing to GUIs, you can of course also
373 directly edit the the actions files with your favorite text editor.
374 Look at <tt class="FILENAME">default.action</tt> which is richly
375 commented with many good examples.</p>
379 <h2 class="SECT2"><a name="ACTIONS-APPLY" id="ACTIONS-APPLY">8.3. How
380 Actions are Applied to Requests</a></h2>
382 <p>Actions files are divided into sections. There are special sections,
383 like the <span class="QUOTE">"<a href=
384 "actions-file.html#ALIASES">alias</a>"</span> sections which will be
385 discussed later. For now let's concentrate on regular sections: They
386 have a heading line (often split up to multiple lines for readability)
387 which consist of a list of actions, separated by whitespace and
388 enclosed in curly braces. Below that, there is a list of URL and tag
389 patterns, each on a separate line.</p>
391 <p>To determine which actions apply to a request, the URL of the
392 request is compared to all URL patterns in each <span class=
393 "QUOTE">"action file"</span>. Every time it matches, the list of
394 applicable actions for the request is incrementally updated, using the
395 heading of the section in which the pattern is located. The same is
396 done again for tags and tag patterns later on.</p>
398 <p>If multiple applying sections set the same action differently, the
399 last match wins. If not, the effects are aggregated. E.g. a URL might
400 match a regular section with a heading line of <tt class="LITERAL">{
401 +<a href="actions-file.html#HANDLE-AS-IMAGE">handle-as-image</a>
402 }</tt>, then later another one with just <tt class="LITERAL">{
403 +<a href="actions-file.html#BLOCK">block</a> }</tt>, resulting in
404 <span class="emphasis EMPHASIS c2">both</span> actions to apply. And
405 there may well be cases where you will want to combine actions
406 together. Such a section then might look like:</p>
408 <table class="c4" border="0" width="100%">
412 { +<tt class="LITERAL">handle-as-image</tt> +<tt class=
413 "LITERAL">block{Banner ads.}</tt> }
414 # Block these as if they were images. Send no block page.
416 media.example.com/.*banners
417 .example.com/images/ads/
423 <p>You can trace this process for URL patterns and any given URL by
424 visiting <a href="http://config.privoxy.org/show-url-info" target=
425 "_top">http://config.privoxy.org/show-url-info</a>.</p>
427 <p>Examples and more detail on this is provided in the Appendix,
428 <a href="appendix.html#ACTIONSANAT">Troubleshooting: Anatomy of an
429 Action</a> section.</p>
433 <h2 class="SECT2"><a name="AF-PATTERNS" id="AF-PATTERNS">8.4.
436 <p>As mentioned, <span class="APPLICATION">Privoxy</span> uses
437 <span class="QUOTE">"patterns"</span> to determine what <span class=
438 "emphasis EMPHASIS c2">actions</span> might apply to which sites and
439 pages your browser attempts to access. These <span class=
440 "QUOTE">"patterns"</span> use wild card type <span class=
441 "emphasis EMPHASIS c2">pattern</span> matching to achieve a high degree
442 of flexibility. This allows one expression to be expanded and
443 potentially match against many similar patterns.</p>
445 <p>Generally, an URL pattern has the form <tt class=
446 "LITERAL"><domain><port>/<path></tt>, where the
447 <tt class="LITERAL"><domain></tt>, the <tt class=
448 "LITERAL"><port></tt> and the <tt class=
449 "LITERAL"><path></tt> are optional. (This is why the special
450 <tt class="LITERAL">/</tt> pattern matches all URLs). Note that the
451 protocol portion of the URL pattern (e.g. <tt class=
452 "LITERAL">http://</tt>) should <span class=
453 "emphasis EMPHASIS c2">not</span> be included in the pattern. This is
456 <p>The pattern matching syntax is different for the domain and path
457 parts of the URL. The domain part uses a simple globbing type matching
458 technique, while the path part uses more flexible <a href=
459 "http://en.wikipedia.org/wiki/Regular_expressions" target=
460 "_top"><span class="QUOTE">"Regular Expressions"</span></a> (POSIX
463 <p>The port part of a pattern is a decimal port number preceded by a
464 colon (<tt class="LITERAL">:</tt>). If the domain part contains a
465 numerical IPv6 address, it has to be put into angle brackets
466 (<tt class="LITERAL"><</tt>, <tt class="LITERAL">></tt>).</p>
468 <div class="VARIABLELIST">
470 <dt><tt class="LITERAL">www.example.com/</tt></dt>
473 <p>is a domain-only pattern and will match any request to
474 <tt class="LITERAL">www.example.com</tt>, regardless of which
475 document on that server is requested. So ALL pages in this domain
476 would be covered by the scope of this action. Note that a simple
477 <tt class="LITERAL">example.com</tt> is different and would NOT
481 <dt><tt class="LITERAL">www.example.com</tt></dt>
484 <p>means exactly the same. For domain-only patterns, the trailing
485 <tt class="LITERAL">/</tt> may be omitted.</p>
488 <dt><tt class="LITERAL">www.example.com/index.html</tt></dt>
491 <p>matches all the documents on <tt class=
492 "LITERAL">www.example.com</tt> whose name starts with <tt class=
493 "LITERAL">/index.html</tt>.</p>
496 <dt><tt class="LITERAL">www.example.com/index.html$</tt></dt>
499 <p>matches only the single document <tt class=
500 "LITERAL">/index.html</tt> on <tt class=
501 "LITERAL">www.example.com</tt>.</p>
504 <dt><tt class="LITERAL">/index.html$</tt></dt>
507 <p>matches the document <tt class="LITERAL">/index.html</tt>,
508 regardless of the domain, i.e. on <span class=
509 "emphasis EMPHASIS c2">any</span> web server anywhere.</p>
512 <dt><tt class="LITERAL">/</tt></dt>
515 <p>Matches any URL because there's no requirement for either the
516 domain or the path to match anything.</p>
519 <dt><tt class="LITERAL">:8000/</tt></dt>
522 <p>Matches any URL pointing to TCP port 8000.</p>
525 <dt><tt class="LITERAL"><2001:db8::1>/</tt></dt>
528 <p>Matches any URL with the host address <tt class=
529 "LITERAL">2001:db8::1</tt>. (Note that the real URL uses plain
530 brackets, not angle brackets.)</p>
533 <dt><tt class="LITERAL">index.html</tt></dt>
536 <p>matches nothing, since it would be interpreted as a domain
537 name and there is no top-level domain called <tt class=
538 "LITERAL">.html</tt>. So its a mistake.</p>
544 <h3 class="SECT3"><a name="AEN3017" id="AEN3017">8.4.1. The Domain
547 <p>The matching of the domain part offers some flexible options: if
548 the domain starts or ends with a dot, it becomes unanchored at that
549 end. For example:</p>
551 <div class="VARIABLELIST">
553 <dt><tt class="LITERAL">.example.com</tt></dt>
556 <p>matches any domain with first-level domain <tt class=
557 "LITERAL">com</tt> and second-level domain <tt class=
558 "LITERAL">example</tt>. For example <tt class=
559 "LITERAL">www.example.com</tt>, <tt class=
560 "LITERAL">example.com</tt> and <tt class=
561 "LITERAL">foo.bar.baz.example.com</tt>. Note that it wouldn't
562 match if the second-level domain was <tt class=
563 "LITERAL">another-example</tt>.</p>
566 <dt><tt class="LITERAL">www.</tt></dt>
569 <p>matches any domain that <span class=
570 "emphasis EMPHASIS c2">STARTS</span> with <tt class=
571 "LITERAL">www.</tt> (It also matches the domain <tt class=
572 "LITERAL">www</tt> but most of the time that doesn't
576 <dt><tt class="LITERAL">.example.</tt></dt>
579 <p>matches any domain that <span class=
580 "emphasis EMPHASIS c2">CONTAINS</span> <tt class=
581 "LITERAL">.example.</tt>. And, by the way, also included would
582 be any files or documents that exist within that domain since
583 no path limitations are specified. (Correctly speaking: It
584 matches any FQDN that contains <tt class="LITERAL">example</tt>
585 as a domain.) This might be <tt class=
586 "LITERAL">www.example.com</tt>, <tt class=
587 "LITERAL">news.example.de</tt>, or <tt class=
588 "LITERAL">www.example.net/cgi/testing.pl</tt> for instance. All
589 these cases are matched.</p>
594 <p>Additionally, there are wild-cards that you can use in the domain
595 names themselves. These work similarly to shell globbing type
596 wild-cards: <span class="QUOTE">"*"</span> represents zero or more
597 arbitrary characters (this is equivalent to the <a href=
598 "http://en.wikipedia.org/wiki/Regular_expressions" target=
599 "_top"><span class="QUOTE">"Regular Expression"</span></a> based
600 syntax of <span class="QUOTE">".*"</span>), <span class=
601 "QUOTE">"?"</span> represents any single character (this is
602 equivalent to the regular expression syntax of a simple <span class=
603 "QUOTE">"."</span>), and you can define <span class=
604 "QUOTE">"character classes"</span> in square brackets which is
605 similar to the same regular expression technique. All of this can be
608 <div class="VARIABLELIST">
610 <dt><tt class="LITERAL">ad*.example.com</tt></dt>
613 <p>matches <span class="QUOTE">"adserver.example.com"</span>,
614 <span class="QUOTE">"ads.example.com"</span>, etc but not
615 <span class="QUOTE">"sfads.example.com"</span></p>
618 <dt><tt class="LITERAL">*ad*.example.com</tt></dt>
621 <p>matches all of the above, and then some.</p>
624 <dt><tt class="LITERAL">.?pix.com</tt></dt>
627 <p>matches <tt class="LITERAL">www.ipix.com</tt>, <tt class=
628 "LITERAL">pictures.epix.com</tt>, <tt class=
629 "LITERAL">a.b.c.d.e.upix.com</tt> etc.</p>
632 <dt><tt class="LITERAL">www[1-9a-ez].example.c*</tt></dt>
635 <p>matches <tt class="LITERAL">www1.example.com</tt>,
636 <tt class="LITERAL">www4.example.cc</tt>, <tt class=
637 "LITERAL">wwwd.example.cy</tt>, <tt class=
638 "LITERAL">wwwz.example.com</tt> etc., but <span class=
639 "emphasis EMPHASIS c2">not</span> <tt class=
640 "LITERAL">wwww.example.com</tt>.</p>
645 <p>While flexible, this is not the sophistication of full regular
646 expression based syntax.</p>
650 <h3 class="SECT3"><a name="AEN3093" id="AEN3093">8.4.2. The Path
653 <p><span class="APPLICATION">Privoxy</span> uses <span class=
654 "QUOTE">"modern"</span> POSIX 1003.2 <a href=
655 "http://en.wikipedia.org/wiki/Regular_expressions" target=
656 "_top"><span class="QUOTE">"Regular Expressions"</span></a> for
657 matching the path portion (after the slash), and is thus more
660 <p>There is an <a href="appendix.html#REGEX">Appendix</a> with a
661 brief quick-start into regular expressions, you also might want to
662 have a look at your operating system's documentation on regular
663 expressions (try <tt class="LITERAL">man re_format</tt>).</p>
665 <p>Note that the path pattern is automatically left-anchored at the
666 <span class="QUOTE">"/"</span>, i.e. it matches as if it would start
667 with a <span class="QUOTE">"^"</span> (regular expression speak for
668 the beginning of a line).</p>
670 <p>Please also note that matching in the path is <span class=
671 "emphasis EMPHASIS c2">CASE INSENSITIVE</span> by default, but you
672 can switch to case sensitive at any point in the pattern by using the
673 <span class="QUOTE">"(?-i)"</span> switch: <tt class=
674 "LITERAL">www.example.com/(?-i)PaTtErN.*</tt> will match only
675 documents whose path starts with <tt class="LITERAL">PaTtErN</tt> in
676 <span class="emphasis EMPHASIS c2">exactly</span> this
679 <div class="VARIABLELIST">
681 <dt><tt class="LITERAL">.example.com/.*</tt></dt>
684 <p>Is equivalent to just <span class=
685 "QUOTE">".example.com"</span>, since any documents within that
686 domain are matched with or without the <span class=
687 "QUOTE">".*"</span> regular expression. This is redundant</p>
690 <dt><tt class="LITERAL">.example.com/.*/index.html$</tt></dt>
693 <p>Will match any page in the domain of <span class=
694 "QUOTE">"example.com"</span> that is named <span class=
695 "QUOTE">"index.html"</span>, and that is part of some path. For
696 example, it matches <span class=
697 "QUOTE">"www.example.com/testing/index.html"</span> but NOT
698 <span class="QUOTE">"www.example.com/index.html"</span> because
699 the regular expression called for at least two <span class=
700 "QUOTE">"/'s"</span>, thus the path requirement. It also would
702 "QUOTE">"www.example.com/testing/index_html"</span>, because of
703 the special meta-character <span class="QUOTE">"."</span>.</p>
706 <dt><tt class="LITERAL">.example.com/(.*/)?index\.html$</tt></dt>
709 <p>This regular expression is conditional so it will match any
710 page named <span class="QUOTE">"index.html"</span> regardless
711 of path which in this case can have one or more <span class=
712 "QUOTE">"/'s"</span>. And this one must contain exactly
713 <span class="QUOTE">".html"</span> (but does not have to end
718 "LITERAL">.example.com/(.*/)(ads|banners?|junk)</tt></dt>
721 <p>This regular expression will match any path of <span class=
722 "QUOTE">"example.com"</span> that contains any of the words
723 <span class="QUOTE">"ads"</span>, <span class=
724 "QUOTE">"banner"</span>, <span class="QUOTE">"banners"</span>
725 (because of the <span class="QUOTE">"?"</span>) or <span class=
726 "QUOTE">"junk"</span>. The path does not have to end in these
727 words, just contain them.</p>
731 "LITERAL">.example.com/(.*/)(ads|banners?|junk)/.*\.(jpe?g|gif|png)$</tt></dt>
734 <p>This is very much the same as above, except now it must end
735 in either <span class="QUOTE">".jpg"</span>, <span class=
736 "QUOTE">".jpeg"</span>, <span class="QUOTE">".gif"</span> or
737 <span class="QUOTE">".png"</span>. So this one is limited to
738 common image formats.</p>
743 <p>There are many, many good examples to be found in <tt class=
744 "FILENAME">default.action</tt>, and more tutorials below in <a href=
745 "appendix.html#REGEX">Appendix on regular expressions</a>.</p>
749 <h3 class="SECT3"><a name="TAG-PATTERN" id="TAG-PATTERN">8.4.3. The
752 <p>Tag patterns are used to change the applying actions based on the
753 request's tags. Tags can be created with either the <a href=
754 "actions-file.html#CLIENT-HEADER-TAGGER">client-header-tagger</a> or
756 "actions-file.html#SERVER-HEADER-TAGGER">server-header-tagger</a>
759 <p>Tag patterns have to start with <span class="QUOTE">"TAG:"</span>,
760 so <span class="APPLICATION">Privoxy</span> can tell them apart from
761 URL patterns. Everything after the colon including white space, is
762 interpreted as a regular expression with path pattern syntax, except
763 that tag patterns aren't left-anchored automatically (<span class=
764 "APPLICATION">Privoxy</span> doesn't silently add a <span class=
765 "QUOTE">"^"</span>, you have to do it yourself if you need it).</p>
767 <p>To match all requests that are tagged with <span class=
768 "QUOTE">"foo"</span> your pattern line should be <span class=
769 "QUOTE">"TAG:^foo$"</span>, <span class="QUOTE">"TAG:foo"</span>
770 would work as well, but it would also match requests whose tags
771 contain <span class="QUOTE">"foo"</span> somewhere. <span class=
772 "QUOTE">"TAG: foo"</span> wouldn't work as it requires white
775 <p>Sections can contain URL and tag patterns at the same time, but
776 tag patterns are checked after the URL patterns and thus always
777 overrule them, even if they are located before the URL patterns.</p>
779 <p>Once a new tag is added, Privoxy checks right away if it's matched
780 by one of the tag patterns and updates the action settings
781 accordingly. As a result tags can be used to activate other tagger
782 actions, as long as these other taggers look for headers that haven't
783 already be parsed.</p>
785 <p>For example you could tag client requests which use the <tt class=
786 "LITERAL">POST</tt> method, then use this tag to activate another
787 tagger that adds a tag if cookies are sent, and then use a block
788 action based on the cookie tag. This allows the outcome of one
789 action, to be input into a subsequent action. However if you'd
790 reverse the position of the described taggers, and activated the
791 method tagger based on the cookie tagger, no method tags would be
792 created. The method tagger would look for the request line, but at
793 the time the cookie tag is created, the request line has already been
796 <p>While this is a limitation you should be aware of, this kind of
797 indirection is seldom needed anyway and even the example doesn't make
803 <h2 class="SECT2"><a name="ACTIONS" id="ACTIONS">8.5. Actions</a></h2>
805 <p>All actions are disabled by default, until they are explicitly
806 enabled somewhere in an actions file. Actions are turned on if preceded
807 with a <span class="QUOTE">"+"</span>, and turned off if preceded with
808 a <span class="QUOTE">"-"</span>. So a <tt class="LITERAL">+action</tt>
809 means <span class="QUOTE">"do that action"</span>, e.g. <tt class=
810 "LITERAL">+block</tt> means <span class="QUOTE">"please block URLs that
811 match the following patterns"</span>, and <tt class=
812 "LITERAL">-block</tt> means <span class="QUOTE">"don't block URLs that
813 match the following patterns, even if <tt class="LITERAL">+block</tt>
814 previously applied."</span></p>
816 <p>Again, actions are invoked by placing them on a line, enclosed in
817 curly braces and separated by whitespace, like in <tt class=
818 "LITERAL">{+some-action -some-other-action{some-parameter}}</tt>,
819 followed by a list of URL patterns, one per line, to which they apply.
820 Together, the actions line and the following pattern lines make up a
821 section of the actions file.</p>
823 <p>Actions fall into three categories:</p>
827 <p>Boolean, i.e the action can only be <span class=
828 "QUOTE">"enabled"</span> or <span class="QUOTE">"disabled"</span>.
831 <table class="c4" border="0" width="90%">
835 +<tt class="REPLACEABLE c5">name</tt> # enable action <tt class=
836 "REPLACEABLE c5">name</tt>
837 -<tt class="REPLACEABLE c5">name</tt> # disable action <tt class=
838 "REPLACEABLE c5">name</tt>
844 <p>Example: <tt class="LITERAL">+handle-as-image</tt></p>
848 <p>Parameterized, where some value is required in order to enable
849 this type of action. Syntax:</p>
851 <table class="c4" border="0" width="90%">
855 +<tt class="REPLACEABLE c5">name</tt>{<tt class=
856 "REPLACEABLE c5">param</tt>} # enable action and set parameter to <tt class=
857 "REPLACEABLE c5">param</tt>,
858 # overwriting parameter from previous match if necessary
860 "REPLACEABLE c5">name</tt> # disable action. The parameter can be omitted
866 <p>Note that if the URL matches multiple positive forms of a
867 parameterized action, the last match wins, i.e. the params from
868 earlier matches are simply ignored.</p>
870 <p>Example: <tt class="LITERAL">+hide-user-agent{Mozilla/5.0 (X11;
871 U; FreeBSD i386; en-US; rv:1.8.1.4) Gecko/20070602
872 Firefox/2.0.0.4}</tt></p>
876 <p>Multi-value. These look exactly like parameterized actions, but
877 they behave differently: If the action applies multiple times to
878 the same URL, but with different parameters, <span class=
879 "emphasis EMPHASIS c2">all</span> the parameters from <span class=
880 "emphasis EMPHASIS c2">all</span> matches are remembered. This is
881 used for actions that can be executed for the same request
882 repeatedly, like adding multiple headers, or filtering through
883 multiple filters. Syntax:</p>
885 <table class="c4" border="0" width="90%">
889 +<tt class="REPLACEABLE c5">name</tt>{<tt class=
890 "REPLACEABLE c5">param</tt>} # enable action and add <tt class=
891 "REPLACEABLE c5">param</tt> to the list of parameters
892 -<tt class="REPLACEABLE c5">name</tt>{<tt class=
893 "REPLACEABLE c5">param</tt>} # remove the parameter <tt class=
894 "REPLACEABLE c5">param</tt> from the list of parameters
895 # If it was the last one left, disable the action.
897 "REPLACEABLE c5">-name</tt> # disable this action completely and remove all parameters from the list
903 <p>Examples: <tt class="LITERAL">+add-header{X-Fun-Header: Some
904 text}</tt> and <tt class=
905 "LITERAL">+filter{html-annoyances}</tt></p>
909 <p>If nothing is specified in any actions file, no <span class=
910 "QUOTE">"actions"</span> are taken. So in this case <span class=
911 "APPLICATION">Privoxy</span> would just be a normal, non-blocking,
912 non-filtering proxy. You must specifically enable the privacy and
913 blocking features you need (although the provided default actions files
914 will give a good starting point).</p>
916 <p>Later defined action sections always over-ride earlier ones of the
917 same type. So exceptions to any rules you make, should come in the
918 latter part of the file (or in a file that is processed later when
919 using multiple actions files such as <tt class=
920 "FILENAME">user.action</tt>). For multi-valued actions, the actions are
921 applied in the order they are specified. Actions files are processed in
922 the order they are defined in <tt class="FILENAME">config</tt> (the
923 default installation has three actions files). It also quite possible
924 for any given URL to match more than one <span class=
925 "QUOTE">"pattern"</span> (because of wildcards and regular
926 expressions), and thus to trigger more than one set of actions! Last
929 <p>The list of valid <span class="APPLICATION">Privoxy</span> actions
933 <h4 class="SECT3"><a name="ADD-HEADER" id="ADD-HEADER">8.5.1.
936 <div class="VARIABLELIST">
938 <dt>Typical use:</dt>
941 <p>Confuse log analysis, custom applications</p>
947 <p>Sends a user defined HTTP header to the web server.</p>
959 <p>Any string value is possible. Validity of the defined HTTP
960 headers is not checked. It is recommended that you use the
961 <span class="QUOTE">"<tt class="LITERAL">X-</tt>"</span> prefix
962 for custom headers.</p>
968 <p>This action may be specified multiple times, in order to
969 define multiple headers. This is rarely needed for the typical
970 user. If you don't know what <span class="QUOTE">"HTTP
971 headers"</span> are, you definitely don't need to worry about
974 <p>Headers added by this action are not modified by other
978 <dt>Example usage:</dt>
981 <table class="c4" border="0" width="90%">
985 +add-header{X-User-Tracking: sucks}
996 <h4 class="SECT3"><a name="BLOCK" id="BLOCK">8.5.2. block</a></h4>
998 <div class="VARIABLELIST">
1000 <dt>Typical use:</dt>
1003 <p>Block ads or other unwanted content</p>
1009 <p>Requests for URLs to which this action applies are blocked,
1010 i.e. the requests are trapped by <span class=
1011 "APPLICATION">Privoxy</span> and the requested URL is never
1012 retrieved, but is answered locally with a substitute page or
1013 image, as determined by the <tt class="LITERAL"><a href=
1014 "actions-file.html#HANDLE-AS-IMAGE">handle-as-image</a></tt>,
1015 <tt class="LITERAL"><a href=
1016 "actions-file.html#SET-IMAGE-BLOCKER">set-image-blocker</a></tt>,
1017 and <tt class="LITERAL"><a href=
1018 "actions-file.html#HANDLE-AS-EMPTY-DOCUMENT">handle-as-empty-document</a></tt>
1025 <p>Parameterized.</p>
1031 <p>A block reason that should be given to the user.</p>
1037 <p><span class="APPLICATION">Privoxy</span> sends a special
1038 <span class="QUOTE">"BLOCKED"</span> page for requests to
1039 blocked pages. This page contains the block reason given as
1040 parameter, a link to find out why the block action applies, and
1041 a click-through to the blocked content (the latter only if the
1042 force feature is available and enabled).</p>
1044 <p>A very important exception occurs if <span class=
1045 "emphasis EMPHASIS c2">both</span> <tt class=
1046 "LITERAL">block</tt> and <tt class="LITERAL"><a href=
1047 "actions-file.html#HANDLE-AS-IMAGE">handle-as-image</a></tt>,
1048 apply to the same request: it will then be replaced by an
1049 image. If <tt class="LITERAL"><a href=
1050 "actions-file.html#SET-IMAGE-BLOCKER">set-image-blocker</a></tt>
1051 (see below) also applies, the type of image will be determined
1052 by its parameter, if not, the standard checkerboard pattern is
1055 <p>It is important to understand this process, in order to
1056 understand how <span class="APPLICATION">Privoxy</span> deals
1057 with ads and other unwanted content. Blocking is a core
1058 feature, and one upon which various other features depend.</p>
1060 <p>The <tt class="LITERAL"><a href=
1061 "actions-file.html#FILTER">filter</a></tt> action can perform a
1062 very similar task, by <span class="QUOTE">"blocking"</span>
1063 banner images and other content through rewriting the relevant
1064 URLs in the document's HTML source, so they don't get requested
1065 in the first place. Note that this is a totally different
1066 technique, and it's easy to confuse the two.</p>
1069 <dt>Example usage (section):</dt>
1072 <table class="c4" border="0" width="90%">
1075 <pre class="SCREEN">
1076 {+block{No nasty stuff for you.}}
1077 # Block and replace with "blocked" page
1078 .nasty-stuff.example.com
1080 {+block{Doubleclick banners.} +handle-as-image}
1081 # Block and replace with image
1085 {+block{Layered ads.} +handle-as-empty-document}
1086 # Block and then ignore
1087 adserver.example.net/.*\.js$
1098 <h4 class="SECT3"><a name="CHANGE-X-FORWARDED-FOR" id=
1099 "CHANGE-X-FORWARDED-FOR">8.5.3. change-x-forwarded-for</a></h4>
1101 <div class="VARIABLELIST">
1103 <dt>Typical use:</dt>
1106 <p>Improve privacy by not forwarding the source of the request
1107 in the HTTP headers.</p>
1113 <p>Deletes the <span class="QUOTE">"X-Forwarded-For:"</span>
1114 HTTP header from the client request, or adds a new one.</p>
1120 <p>Parameterized.</p>
1128 <p><span class="QUOTE">"block"</span> to delete the
1133 <p><span class="QUOTE">"add"</span> to create the header
1134 (or append the client's IP address to an already existing
1143 <p>It is safe and recommended to use <tt class=
1144 "LITERAL">block</tt>.</p>
1146 <p>Forwarding the source address of the request may make sense
1147 in some multi-user setups but is also a privacy risk.</p>
1150 <dt>Example usage:</dt>
1153 <table class="c4" border="0" width="90%">
1156 <pre class="SCREEN">
1157 +change-x-forwarded-for{block}
1168 <h4 class="SECT3"><a name="CLIENT-HEADER-FILTER" id=
1169 "CLIENT-HEADER-FILTER">8.5.4. client-header-filter</a></h4>
1171 <div class="VARIABLELIST">
1173 <dt>Typical use:</dt>
1176 <p>Rewrite or remove single client headers.</p>
1182 <p>All client headers to which this action applies are filtered
1183 on-the-fly through the specified regular expression based
1190 <p>Parameterized.</p>
1196 <p>The name of a client-header filter, as defined in one of the
1197 <a href="filter-file.html">filter files</a>.</p>
1203 <p>Client-header filters are applied to each header on its own,
1204 not to all at once. This makes it easier to diagnose problems,
1205 but on the downside you can't write filters that only change
1206 header x if header y's value is z. You can do that by using
1209 <p>Client-header filters are executed after the other header
1210 actions have finished and use their output as input.</p>
1212 <p>If the request URL gets changed, <span class=
1213 "APPLICATION">Privoxy</span> will detect that and use the new
1214 one. This can be used to rewrite the request destination behind
1215 the client's back, for example to specify a Tor exit relay for
1216 certain requests.</p>
1218 <p>Please refer to the <a href="filter-file.html">filter file
1219 chapter</a> to learn which client-header filters are available
1220 by default, and how to create your own.</p>
1223 <dt>Example usage (section):</dt>
1226 <table class="c4" border="0" width="90%">
1229 <pre class="SCREEN">
1230 # Hide Tor exit notation in Host and Referer Headers
1231 {+client-header-filter{hide-tor-exit-notation}}
1244 <h4 class="SECT3"><a name="CLIENT-HEADER-TAGGER" id=
1245 "CLIENT-HEADER-TAGGER">8.5.5. client-header-tagger</a></h4>
1247 <div class="VARIABLELIST">
1249 <dt>Typical use:</dt>
1252 <p>Block requests based on their headers.</p>
1258 <p>Client headers to which this action applies are filtered
1259 on-the-fly through the specified regular expression based
1260 substitutions, the result is used as tag.</p>
1266 <p>Parameterized.</p>
1272 <p>The name of a client-header tagger, as defined in one of the
1273 <a href="filter-file.html">filter files</a>.</p>
1279 <p>Client-header taggers are applied to each header on its own,
1280 and as the header isn't modified, each tagger <span class=
1281 "QUOTE">"sees"</span> the original.</p>
1283 <p>Client-header taggers are the first actions that are
1284 executed and their tags can be used to control every other
1288 <dt>Example usage (section):</dt>
1291 <table class="c4" border="0" width="90%">
1294 <pre class="SCREEN">
1295 # Tag every request with the User-Agent header
1296 {+client-header-tagger{user-agent}}
1299 # Tagging itself doesn't change the action
1300 # settings, sections with TAG patterns do:
1302 # If it's a download agent, use a different forwarding proxy,
1303 # show the real User-Agent and make sure resume works.
1304 {+forward-override{forward-socks5 10.0.0.2:2222 .} \
1305 -hide-if-modified-since \
1306 -overwrite-last-modified \
1311 TAG:^User-Agent: NetBSD-ftp/
1312 TAG:^User-Agent: Novell ZYPP Installer
1313 TAG:^User-Agent: RPM APT-HTTP/
1314 TAG:^User-Agent: fetch libfetch/
1315 TAG:^User-Agent: Ubuntu APT-HTTP/
1316 TAG:^User-Agent: MPlayer/
1328 <h4 class="SECT3"><a name="CONTENT-TYPE-OVERWRITE" id=
1329 "CONTENT-TYPE-OVERWRITE">8.5.6. content-type-overwrite</a></h4>
1331 <div class="VARIABLELIST">
1333 <dt>Typical use:</dt>
1336 <p>Stop useless download menus from popping up, or change the
1337 browser's rendering mode</p>
1343 <p>Replaces the <span class="QUOTE">"Content-Type:"</span> HTTP
1350 <p>Parameterized.</p>
1362 <p>The <span class="QUOTE">"Content-Type:"</span> HTTP server
1363 header is used by the browser to decide what to do with the
1364 document. The value of this header can cause the browser to
1365 open a download menu instead of displaying the document by
1366 itself, even if the document's format is supported by the
1369 <p>The declared content type can also affect which rendering
1370 mode the browser chooses. If XHTML is delivered as <span class=
1371 "QUOTE">"text/html"</span>, many browsers treat it as yet
1372 another broken HTML document. If it is send as <span class=
1373 "QUOTE">"application/xml"</span>, browsers with XHTML support
1374 will only display it, if the syntax is correct.</p>
1376 <p>If you see a web site that proudly uses XHTML buttons, but
1377 sets <span class="QUOTE">"Content-Type: text/html"</span>, you
1378 can use <span class="APPLICATION">Privoxy</span> to overwrite
1379 it with <span class="QUOTE">"application/xml"</span> and
1380 validate the web master's claim inside your XHTML-supporting
1381 browser. If the syntax is incorrect, the browser will complain
1384 <p>You can also go the opposite direction: if your browser
1385 prints error messages instead of rendering a document falsely
1386 declared as XHTML, you can overwrite the content type with
1387 <span class="QUOTE">"text/html"</span> and have it rendered as
1388 broken HTML document.</p>
1390 <p>By default <tt class="LITERAL">content-type-overwrite</tt>
1391 only replaces <span class="QUOTE">"Content-Type:"</span>
1392 headers that look like some kind of text. If you want to
1393 overwrite it unconditionally, you have to combine it with
1394 <tt class="LITERAL"><a href=
1395 "actions-file.html#FORCE-TEXT-MODE">force-text-mode</a></tt>.
1396 This limitation exists for a reason, think twice before
1397 circumventing it.</p>
1399 <p>Most of the time it's easier to replace this action with a
1400 custom <tt class="LITERAL"><a href=
1401 "actions-file.html#SERVER-HEADER-FILTER">server-header
1402 filter</a></tt>. It allows you to activate it for every
1403 document of a certain site and it will still only replace the
1404 content types you aimed at.</p>
1406 <p>Of course you can apply <tt class=
1407 "LITERAL">content-type-overwrite</tt> to a whole site and then
1408 make URL based exceptions, but it's a lot more work to get the
1412 <dt>Example usage (sections):</dt>
1415 <table class="c4" border="0" width="90%">
1418 <pre class="SCREEN">
1419 # Check if www.example.net/ really uses valid XHTML
1420 { +content-type-overwrite{application/xml} }
1423 # but leave the content type unmodified if the URL looks like a style sheet
1424 {-content-type-overwrite}
1425 www.example.net/.*\.css$
1426 www.example.net/.*style
1437 <h4 class="SECT3"><a name="CRUNCH-CLIENT-HEADER" id=
1438 "CRUNCH-CLIENT-HEADER">8.5.7. crunch-client-header</a></h4>
1440 <div class="VARIABLELIST">
1442 <dt>Typical use:</dt>
1445 <p>Remove a client header <span class=
1446 "APPLICATION">Privoxy</span> has no dedicated action for.</p>
1452 <p>Deletes every header sent by the client that contains the
1453 string the user supplied as parameter.</p>
1459 <p>Parameterized.</p>
1471 <p>This action allows you to block client headers for which no
1472 dedicated <span class="APPLICATION">Privoxy</span> action
1473 exists. <span class="APPLICATION">Privoxy</span> will remove
1474 every client header that contains the string you supplied as
1477 <p>Regular expressions are <span class=
1478 "emphasis EMPHASIS c2">not supported</span> and you can't use
1479 this action to block different headers in the same request,
1480 unless they contain the same string.</p>
1482 <p><tt class="LITERAL">crunch-client-header</tt> is only meant
1483 for quick tests. If you have to block several different
1484 headers, or only want to modify parts of them, you should use a
1485 <tt class="LITERAL"><a href=
1486 "actions-file.html#CLIENT-HEADER-FILTER">client-header
1487 filter</a></tt>.</p>
1489 <div class="WARNING">
1490 <table class="WARNING" border="1" width="90%">
1492 <td class="c6" align="center">Warning</td>
1497 <p>Don't block any header without understanding the
1505 <dt>Example usage (section):</dt>
1508 <table class="c4" border="0" width="90%">
1511 <pre class="SCREEN">
1512 # Block the non-existent "Privacy-Violation:" client header
1513 { +crunch-client-header{Privacy-Violation:} }
1526 <h4 class="SECT3"><a name="CRUNCH-IF-NONE-MATCH" id=
1527 "CRUNCH-IF-NONE-MATCH">8.5.8. crunch-if-none-match</a></h4>
1529 <div class="VARIABLELIST">
1531 <dt>Typical use:</dt>
1534 <p>Prevent yet another way to track the user's steps between
1541 <p>Deletes the <span class="QUOTE">"If-None-Match:"</span> HTTP
1560 <p>Removing the <span class="QUOTE">"If-None-Match:"</span>
1561 HTTP client header is useful for filter testing, where you want
1562 to force a real reload instead of getting status code
1563 <span class="QUOTE">"304"</span> which would cause the browser
1564 to use a cached copy of the page.</p>
1566 <p>It is also useful to make sure the header isn't used as a
1567 cookie replacement (unlikely but possible).</p>
1569 <p>Blocking the <span class="QUOTE">"If-None-Match:"</span>
1570 header shouldn't cause any caching problems, as long as the
1571 <span class="QUOTE">"If-Modified-Since:"</span> header isn't
1572 blocked or missing as well.</p>
1574 <p>It is recommended to use this action together with
1575 <tt class="LITERAL"><a href=
1576 "actions-file.html#HIDE-IF-MODIFIED-SINCE">hide-if-modified-since</a></tt>
1577 and <tt class="LITERAL"><a href=
1578 "actions-file.html#OVERWRITE-LAST-MODIFIED">overwrite-last-modified</a></tt>.</p>
1581 <dt>Example usage (section):</dt>
1584 <table class="c4" border="0" width="90%">
1587 <pre class="SCREEN">
1588 # Let the browser revalidate cached documents but don't
1589 # allow the server to use the revalidation headers for user tracking.
1590 {+hide-if-modified-since{-60} \
1591 +overwrite-last-modified{randomize} \
1592 +crunch-if-none-match}
1604 <h4 class="SECT3"><a name="CRUNCH-INCOMING-COOKIES" id=
1605 "CRUNCH-INCOMING-COOKIES">8.5.9. crunch-incoming-cookies</a></h4>
1607 <div class="VARIABLELIST">
1609 <dt>Typical use:</dt>
1612 <p>Prevent the web server from setting HTTP cookies on your
1619 <p>Deletes any <span class="QUOTE">"Set-Cookie:"</span> HTTP
1620 headers from server replies.</p>
1638 <p>This action is only concerned with <span class=
1639 "emphasis EMPHASIS c2">incoming</span> HTTP cookies. For
1640 <span class="emphasis EMPHASIS c2">outgoing</span> HTTP
1641 cookies, use <tt class="LITERAL"><a href=
1642 "actions-file.html#CRUNCH-OUTGOING-COOKIES">crunch-outgoing-cookies</a></tt>.
1643 Use <span class="emphasis EMPHASIS c2">both</span> to disable
1644 HTTP cookies completely.</p>
1646 <p>It makes <span class="emphasis EMPHASIS c2">no sense at
1647 all</span> to use this action in conjunction with the
1648 <tt class="LITERAL"><a href=
1649 "actions-file.html#SESSION-COOKIES-ONLY">session-cookies-only</a></tt>
1650 action, since it would prevent the session cookies from being
1651 set. See also <tt class="LITERAL"><a href=
1652 "actions-file.html#FILTER-CONTENT-COOKIES">filter-content-cookies</a></tt>.</p>
1655 <dt>Example usage:</dt>
1658 <table class="c4" border="0" width="90%">
1661 <pre class="SCREEN">
1662 +crunch-incoming-cookies
1673 <h4 class="SECT3"><a name="CRUNCH-SERVER-HEADER" id=
1674 "CRUNCH-SERVER-HEADER">8.5.10. crunch-server-header</a></h4>
1676 <div class="VARIABLELIST">
1678 <dt>Typical use:</dt>
1681 <p>Remove a server header <span class=
1682 "APPLICATION">Privoxy</span> has no dedicated action for.</p>
1688 <p>Deletes every header sent by the server that contains the
1689 string the user supplied as parameter.</p>
1695 <p>Parameterized.</p>
1707 <p>This action allows you to block server headers for which no
1708 dedicated <span class="APPLICATION">Privoxy</span> action
1709 exists. <span class="APPLICATION">Privoxy</span> will remove
1710 every server header that contains the string you supplied as
1713 <p>Regular expressions are <span class=
1714 "emphasis EMPHASIS c2">not supported</span> and you can't use
1715 this action to block different headers in the same request,
1716 unless they contain the same string.</p>
1718 <p><tt class="LITERAL">crunch-server-header</tt> is only meant
1719 for quick tests. If you have to block several different
1720 headers, or only want to modify parts of them, you should use a
1721 custom <tt class="LITERAL"><a href=
1722 "actions-file.html#SERVER-HEADER-FILTER">server-header
1723 filter</a></tt>.</p>
1725 <div class="WARNING">
1726 <table class="WARNING" border="1" width="90%">
1728 <td class="c6" align="center">Warning</td>
1733 <p>Don't block any header without understanding the
1741 <dt>Example usage (section):</dt>
1744 <table class="c4" border="0" width="90%">
1747 <pre class="SCREEN">
1748 # Crunch server headers that try to prevent caching
1749 { +crunch-server-header{no-cache} }
1761 <h4 class="SECT3"><a name="CRUNCH-OUTGOING-COOKIES" id=
1762 "CRUNCH-OUTGOING-COOKIES">8.5.11. crunch-outgoing-cookies</a></h4>
1764 <div class="VARIABLELIST">
1766 <dt>Typical use:</dt>
1769 <p>Prevent the web server from reading any HTTP cookies from
1776 <p>Deletes any <span class="QUOTE">"Cookie:"</span> HTTP
1777 headers from client requests.</p>
1795 <p>This action is only concerned with <span class=
1796 "emphasis EMPHASIS c2">outgoing</span> HTTP cookies. For
1797 <span class="emphasis EMPHASIS c2">incoming</span> HTTP
1798 cookies, use <tt class="LITERAL"><a href=
1799 "actions-file.html#CRUNCH-INCOMING-COOKIES">crunch-incoming-cookies</a></tt>.
1800 Use <span class="emphasis EMPHASIS c2">both</span> to disable
1801 HTTP cookies completely.</p>
1803 <p>It makes <span class="emphasis EMPHASIS c2">no sense at
1804 all</span> to use this action in conjunction with the
1805 <tt class="LITERAL"><a href=
1806 "actions-file.html#SESSION-COOKIES-ONLY">session-cookies-only</a></tt>
1807 action, since it would prevent the session cookies from being
1811 <dt>Example usage:</dt>
1814 <table class="c4" border="0" width="90%">
1817 <pre class="SCREEN">
1818 +crunch-outgoing-cookies
1829 <h4 class="SECT3"><a name="DEANIMATE-GIFS" id=
1830 "DEANIMATE-GIFS">8.5.12. deanimate-gifs</a></h4>
1832 <div class="VARIABLELIST">
1834 <dt>Typical use:</dt>
1837 <p>Stop those annoying, distracting animated GIF images.</p>
1843 <p>De-animate GIF animations, i.e. reduce them to their first
1850 <p>Parameterized.</p>
1856 <p><span class="QUOTE">"last"</span> or <span class=
1857 "QUOTE">"first"</span></p>
1863 <p>This will also shrink the images considerably (in bytes, not
1864 pixels!). If the option <span class="QUOTE">"first"</span> is
1865 given, the first frame of the animation is used as the
1866 replacement. If <span class="QUOTE">"last"</span> is given, the
1867 last frame of the animation is used instead, which probably
1868 makes more sense for most banner animations, but also has the
1869 risk of not showing the entire last frame (if it is only a
1870 delta to an earlier frame).</p>
1872 <p>You can safely use this action with patterns that will also
1873 match non-GIF objects, because no attempt will be made at
1874 anything that doesn't look like a GIF.</p>
1877 <dt>Example usage:</dt>
1880 <table class="c4" border="0" width="90%">
1883 <pre class="SCREEN">
1884 +deanimate-gifs{last}
1895 <h4 class="SECT3"><a name="DOWNGRADE-HTTP-VERSION" id=
1896 "DOWNGRADE-HTTP-VERSION">8.5.13. downgrade-http-version</a></h4>
1898 <div class="VARIABLELIST">
1900 <dt>Typical use:</dt>
1903 <p>Work around (very rare) problems with HTTP/1.1</p>
1909 <p>Downgrades HTTP/1.1 client requests and server replies to
1928 <p>This is a left-over from the time when <span class=
1929 "APPLICATION">Privoxy</span> didn't support important HTTP/1.1
1930 features well. It is left here for the unlikely case that you
1931 experience HTTP/1.1-related problems with some server out
1934 <p>Note that enabling this action is only a workaround. It
1935 should not be enabled for sites that work without it. While it
1936 shouldn't break any pages, it has an (usually negative)
1937 performance impact.</p>
1939 <p>If you come across a site where enabling this action helps,
1940 please report it, so the cause of the problem can be analyzed.
1941 If the problem turns out to be caused by a bug in <span class=
1942 "APPLICATION">Privoxy</span> it should be fixed so the
1943 following release works without the work around.</p>
1946 <dt>Example usage (section):</dt>
1949 <table class="c4" border="0" width="90%">
1952 <pre class="SCREEN">
1953 {+downgrade-http-version}
1954 problem-host.example.com
1965 <h4 class="SECT3"><a name="FAST-REDIRECTS" id=
1966 "FAST-REDIRECTS">8.5.14. fast-redirects</a></h4>
1968 <div class="VARIABLELIST">
1970 <dt>Typical use:</dt>
1973 <p>Fool some click-tracking scripts and speed up indirect
1980 <p>Detects redirection URLs and redirects the browser without
1981 contacting the redirection server first.</p>
1987 <p>Parameterized.</p>
1995 <p><span class="QUOTE">"simple-check"</span> to just search
1996 for the string <span class="QUOTE">"http://"</span> to
1997 detect redirection URLs.</p>
2001 <p><span class="QUOTE">"check-decoded-url"</span> to decode
2002 URLs (if necessary) before searching for redirection
2011 <p>Many sites, like yahoo.com, don't just link to other sites.
2012 Instead, they will link to some script on their own servers,
2013 giving the destination as a parameter, which will then redirect
2014 you to the final target. URLs resulting from this scheme
2015 typically look like: <span class=
2016 "QUOTE">"http://www.example.org/click-tracker.cgi?target=http%3a//www.example.net/"</span>.</p>
2018 <p>Sometimes, there are even multiple consecutive redirects
2019 encoded in the URL. These redirections via scripts make your
2020 web browsing more traceable, since the server from which you
2021 follow such a link can see where you go to. Apart from that,
2022 valuable bandwidth and time is wasted, while your browser asks
2023 the server for one redirect after the other. Plus, it feeds the
2026 <p>This feature is currently not very smart and is scheduled
2027 for improvement. If it is enabled by default, you will have to
2028 create some exceptions to this action. It can lead to failures
2029 in several ways:</p>
2031 <p>Not every URLs with other URLs as parameters is evil. Some
2032 sites offer a real service that requires this information to
2033 work. For example a validation service needs to know, which
2034 document to validate. <tt class="LITERAL">fast-redirects</tt>
2035 assumes that every URL parameter that looks like another URL is
2036 a redirection target, and will always redirect to the last one.
2037 Most of the time the assumption is correct, but if it isn't,
2038 the user gets redirected anyway.</p>
2040 <p>Another failure occurs if the URL contains other parameters
2041 after the URL parameter. The URL: <span class=
2042 "QUOTE">"http://www.example.org/?redirect=http%3a//www.example.net/&foo=bar"</span>.
2043 contains the redirection URL <span class=
2044 "QUOTE">"http://www.example.net/"</span>, followed by another
2045 parameter. <tt class="LITERAL">fast-redirects</tt> doesn't know
2046 that and will cause a redirect to <span class=
2047 "QUOTE">"http://www.example.net/&foo=bar"</span>. Depending
2048 on the target server configuration, the parameter will be
2049 silently ignored or lead to a <span class="QUOTE">"page not
2050 found"</span> error. You can prevent this problem by first
2051 using the <tt class="LITERAL"><a href=
2052 "actions-file.html#REDIRECT">redirect</a></tt> action to remove
2053 the last part of the URL, but it requires a little effort.</p>
2055 <p>To detect a redirection URL, <tt class=
2056 "LITERAL">fast-redirects</tt> only looks for the string
2057 <span class="QUOTE">"http://"</span>, either in plain text
2058 (invalid but often used) or encoded as <span class=
2059 "QUOTE">"http%3a//"</span>. Some sites use their own URL
2060 encoding scheme, encrypt the address of the target server or
2061 replace it with a database id. In theses cases <tt class=
2062 "LITERAL">fast-redirects</tt> is fooled and the request reaches
2063 the redirection server where it probably gets logged.</p>
2066 <dt>Example usage:</dt>
2069 <table class="c4" border="0" width="90%">
2072 <pre class="SCREEN">
2073 { +fast-redirects{simple-check} }
2076 { +fast-redirects{check-decoded-url} }
2077 another.example.com/testing
2088 <h4 class="SECT3"><a name="FILTER" id="FILTER">8.5.15.
2091 <div class="VARIABLELIST">
2093 <dt>Typical use:</dt>
2096 <p>Get rid of HTML and JavaScript annoyances, banner
2097 advertisements (by size), do fun text replacements, add
2098 personalized effects, etc.</p>
2104 <p>All instances of text-based type, most notably HTML and
2105 JavaScript, to which this action applies, can be filtered
2106 on-the-fly through the specified regular expression based
2107 substitutions. (Note: as of version 3.0.3 plain text documents
2108 are exempted from filtering, because web servers often use the
2109 <tt class="LITERAL">text/plain</tt> MIME type for all files
2110 whose type they don't know.)</p>
2116 <p>Parameterized.</p>
2122 <p>The name of a content filter, as defined in the <a href=
2123 "filter-file.html">filter file</a>. Filters can be defined in
2124 one or more files as defined by the <tt class=
2125 "LITERAL"><a href="config.html#FILTERFILE">filterfile</a></tt>
2126 option in the <a href="config.html">config file</a>. <tt class=
2127 "FILENAME">default.filter</tt> is the collection of filters
2128 supplied by the developers. Locally defined filters should go
2129 in their own file, such as <tt class=
2130 "FILENAME">user.filter</tt>.</p>
2132 <p>When used in its negative form, and without parameters,
2133 <span class="emphasis EMPHASIS c2">all</span> filtering is
2134 completely disabled.</p>
2140 <p>For your convenience, there are a number of pre-defined
2141 filters available in the distribution filter file that you can
2142 use. See the examples below for a list.</p>
2144 <p>Filtering requires buffering the page content, which may
2145 appear to slow down page rendering since nothing is displayed
2146 until all content has passed the filters. (The total time until
2147 the page is completely rendered doesn't change much, but it may
2148 be perceived as slower since the page is not incrementally
2149 displayed.) This effect will be more noticeable on slower
2152 <p><span class="QUOTE">"Rolling your own"</span> filters
2153 requires a knowledge of <a href=
2154 "http://en.wikipedia.org/wiki/Regular_expressions" target=
2155 "_top"><span class="QUOTE">"Regular Expressions"</span></a> and
2156 <a href="http://en.wikipedia.org/wiki/Html" target=
2157 "_top"><span class="QUOTE">"HTML"</span></a>. This is very
2158 powerful feature, and potentially very intrusive. Filters
2159 should be used with caution, and where an equivalent
2160 <span class="QUOTE">"action"</span> is not available.</p>
2162 <p>The amount of data that can be filtered is limited to the
2163 <tt class="LITERAL"><a href=
2164 "config.html#BUFFER-LIMIT">buffer-limit</a></tt> option in the
2165 main <a href="config.html">config file</a>. The default is 4096
2166 KB (4 Megs). Once this limit is exceeded, the buffered data,
2167 and all pending data, is passed through unfiltered.</p>
2169 <p>Inappropriate MIME types, such as zipped files, are not
2170 filtered at all. (Again, only text-based types except plain
2171 text). Encrypted SSL data (from HTTPS servers) cannot be
2172 filtered either, since this would violate the integrity of the
2173 secure transaction. In some situations it might be necessary to
2174 protect certain text, like source code, from filtering by
2175 defining appropriate <tt class="LITERAL">-filter</tt>
2178 <p>Compressed content can't be filtered either, but if
2179 <span class="APPLICATION">Privoxy</span> is compiled with zlib
2180 support and a supported compression algorithm is used (gzip or
2181 deflate), <span class="APPLICATION">Privoxy</span> can first
2182 decompress the content and then filter it.</p>
2184 <p>If you use a <span class="APPLICATION">Privoxy</span>
2185 version without zlib support, but want filtering to work on as
2186 much documents as possible, even those that would normally be
2187 sent compressed, you must use the <tt class="LITERAL"><a href=
2188 "actions-file.html#PREVENT-COMPRESSION">prevent-compression</a></tt>
2189 action in conjunction with <tt class="LITERAL">filter</tt>.</p>
2191 <p>Content filtering can achieve some of the same effects as
2192 the <tt class="LITERAL"><a href=
2193 "actions-file.html#BLOCK">block</a></tt> action, i.e. it can be
2194 used to block ads and banners. But the mechanism works quite
2195 differently. One effective use, is to block ad banners based on
2196 their size (see below), since many of these seem to be somewhat
2199 <p><a href="contact.html">Feedback</a> with suggestions for new
2200 or improved filters is particularly welcome!</p>
2202 <p>The below list has only the names and a one-line description
2203 of each predefined filter. There are <a href=
2204 "filter-file.html#PREDEFINED-FILTERS">more verbose
2205 explanations</a> of what these filters do in the <a href=
2206 "filter-file.html">filter file chapter</a>.</p>
2209 <dt>Example usage (with filters from the distribution <tt class=
2210 "FILENAME">default.filter</tt> file). See <a href=
2211 "filter-file.html#PREDEFINED-FILTERS">the Predefined Filters
2212 section</a> for more explanation on each:</dt>
2215 <p><a name="FILTER-JS-ANNOYANCES" id=
2216 "FILTER-JS-ANNOYANCES"></a></p>
2218 <table class="c4" border="0" width="90%">
2221 <pre class="SCREEN">
2222 +filter{js-annoyances} # Get rid of particularly annoying JavaScript abuse.
2228 <p><a name="FILTER-JS-EVENTS" id="FILTER-JS-EVENTS"></a></p>
2230 <table class="c4" border="0" width="90%">
2233 <pre class="SCREEN">
2234 +filter{js-events} # Kill all JS event bindings and timers (Radically destructive! Only for extra nasty sites).
2240 <p><a name="FILTER-HTML-ANNOYANCES" id=
2241 "FILTER-HTML-ANNOYANCES"></a></p>
2243 <table class="c4" border="0" width="90%">
2246 <pre class="SCREEN">
2247 +filter{html-annoyances} # Get rid of particularly annoying HTML abuse.
2253 <p><a name="FILTER-CONTENT-COOKIES" id=
2254 "FILTER-CONTENT-COOKIES"></a></p>
2256 <table class="c4" border="0" width="90%">
2259 <pre class="SCREEN">
2260 +filter{content-cookies} # Kill cookies that come in the HTML or JS content.
2266 <p><a name="FILTER-REFRESH-TAGS" id=
2267 "FILTER-REFRESH-TAGS"></a></p>
2269 <table class="c4" border="0" width="90%">
2272 <pre class="SCREEN">
2273 +filter{refresh-tags} # Kill automatic refresh tags (for dial-on-demand setups).
2279 <p><a name="FILTER-UNSOLICITED-POPUPS" id=
2280 "FILTER-UNSOLICITED-POPUPS"></a></p>
2282 <table class="c4" border="0" width="90%">
2285 <pre class="SCREEN">
2286 +filter{unsolicited-popups} # Disable only unsolicited pop-up windows. Useful if your browser lacks this ability.
2292 <p><a name="FILTER-ALL-POPUPS" id="FILTER-ALL-POPUPS"></a></p>
2294 <table class="c4" border="0" width="90%">
2297 <pre class="SCREEN">
2298 +filter{all-popups} # Kill all popups in JavaScript and HTML. Useful if your browser lacks this ability.
2304 <p><a name="FILTER-IMG-REORDER" id=
2305 "FILTER-IMG-REORDER"></a></p>
2307 <table class="c4" border="0" width="90%">
2310 <pre class="SCREEN">
2311 +filter{img-reorder} # Reorder attributes in <img> tags to make the banners-by-* filters more effective.
2317 <p><a name="FILTER-BANNERS-BY-SIZE" id=
2318 "FILTER-BANNERS-BY-SIZE"></a></p>
2320 <table class="c4" border="0" width="90%">
2323 <pre class="SCREEN">
2324 +filter{banners-by-size} # Kill banners by size.
2330 <p><a name="FILTER-BANNERS-BY-LINK" id=
2331 "FILTER-BANNERS-BY-LINK"></a></p>
2333 <table class="c4" border="0" width="90%">
2336 <pre class="SCREEN">
2337 +filter{banners-by-link} # Kill banners by their links to known clicktrackers.
2343 <p><a name="FILTER-WEBBUGS" id="FILTER-WEBBUGS"></a></p>
2345 <table class="c4" border="0" width="90%">
2348 <pre class="SCREEN">
2349 +filter{webbugs} # Squish WebBugs (1x1 invisible GIFs used for user tracking).
2355 <p><a name="FILTER-TINY-TEXTFORMS" id=
2356 "FILTER-TINY-TEXTFORMS"></a></p>
2358 <table class="c4" border="0" width="90%">
2361 <pre class="SCREEN">
2362 +filter{tiny-textforms} # Extend those tiny textareas up to 40x80 and kill the hard wrap.
2368 <p><a name="FILTER-JUMPING-WINDOWS" id=
2369 "FILTER-JUMPING-WINDOWS"></a></p>
2371 <table class="c4" border="0" width="90%">
2374 <pre class="SCREEN">
2375 +filter{jumping-windows} # Prevent windows from resizing and moving themselves.
2381 <p><a name="FILTER-FRAMESET-BORDERS" id=
2382 "FILTER-FRAMESET-BORDERS"></a></p>
2384 <table class="c4" border="0" width="90%">
2387 <pre class="SCREEN">
2388 +filter{frameset-borders} # Give frames a border and make them resizable.
2394 <p><a name="FILTER-DEMORONIZER" id=
2395 "FILTER-DEMORONIZER"></a></p>
2397 <table class="c4" border="0" width="90%">
2400 <pre class="SCREEN">
2401 +filter{demoronizer} # Fix MS's non-standard use of standard charsets.
2407 <p><a name="FILTER-SHOCKWAVE-FLASH" id=
2408 "FILTER-SHOCKWAVE-FLASH"></a></p>
2410 <table class="c4" border="0" width="90%">
2413 <pre class="SCREEN">
2414 +filter{shockwave-flash} # Kill embedded Shockwave Flash objects.
2420 <p><a name="FILTER-QUICKTIME-KIOSKMODE" id=
2421 "FILTER-QUICKTIME-KIOSKMODE"></a></p>
2423 <table class="c4" border="0" width="90%">
2426 <pre class="SCREEN">
2427 +filter{quicktime-kioskmode} # Make Quicktime movies saveable.
2433 <p><a name="FILTER-FUN" id="FILTER-FUN"></a></p>
2435 <table class="c4" border="0" width="90%">
2438 <pre class="SCREEN">
2439 +filter{fun} # Text replacements for subversive browsing fun!
2445 <p><a name="FILTER-CRUDE-PARENTAL" id=
2446 "FILTER-CRUDE-PARENTAL"></a></p>
2448 <table class="c4" border="0" width="90%">
2451 <pre class="SCREEN">
2452 +filter{crude-parental} # Crude parental filtering. Note that this filter doesn't work reliably.
2458 <p><a name="FILTER-IE-EXPLOITS" id=
2459 "FILTER-IE-EXPLOITS"></a></p>
2461 <table class="c4" border="0" width="90%">
2464 <pre class="SCREEN">
2465 +filter{ie-exploits} # Disable some known Internet Explorer bug exploits.
2471 <p><a name="FILTER-SITE-SPECIFICS" id=
2472 "FILTER-SITE-SPECIFICS"></a></p>
2474 <table class="c4" border="0" width="90%">
2477 <pre class="SCREEN">
2478 +filter{site-specifics} # Cure for site-specific problems. Don't apply generally!
2484 <p><a name="FILTER-NO-PING" id="FILTER-NO-PING"></a></p>
2486 <table class="c4" border="0" width="90%">
2489 <pre class="SCREEN">
2490 +filter{no-ping} # Removes non-standard ping attributes in <a> and <area> tags.
2496 <p><a name="FILTER-GOOGLE" id="FILTER-GOOGLE"></a></p>
2498 <table class="c4" border="0" width="90%">
2501 <pre class="SCREEN">
2502 +filter{google} # CSS-based block for Google text ads. Also removes a width limitation and the toolbar advertisement.
2508 <p><a name="FILTER-YAHOO" id="FILTER-YAHOO"></a></p>
2510 <table class="c4" border="0" width="90%">
2513 <pre class="SCREEN">
2514 +filter{yahoo} # CSS-based block for Yahoo text ads. Also removes a width limitation.
2520 <p><a name="FILTER-MSN" id="FILTER-MSN"></a></p>
2522 <table class="c4" border="0" width="90%">
2525 <pre class="SCREEN">
2526 +filter{msn} # CSS-based block for MSN text ads. Also removes tracking URLs and a width limitation.
2532 <p><a name="FILTER-BLOGSPOT" id="FILTER-BLOGSPOT"></a></p>
2534 <table class="c4" border="0" width="90%">
2537 <pre class="SCREEN">
2538 +filter{blogspot} # Cleans up some Blogspot blogs. Read the fine print before using this.
2549 <h4 class="SECT3"><a name="FORCE-TEXT-MODE" id=
2550 "FORCE-TEXT-MODE">8.5.16. force-text-mode</a></h4>
2552 <div class="VARIABLELIST">
2554 <dt>Typical use:</dt>
2557 <p>Force <span class="APPLICATION">Privoxy</span> to treat a
2558 document as if it was in some kind of <span class=
2559 "emphasis EMPHASIS c2">text</span> format.</p>
2565 <p>Declares a document as text, even if the <span class=
2566 "QUOTE">"Content-Type:"</span> isn't detected as such.</p>
2584 <p>As explained <tt class="LITERAL"><a href=
2585 "actions-file.html#FILTER">above</a></tt>, <span class=
2586 "APPLICATION">Privoxy</span> tries to only filter files that
2587 are in some kind of text format. The same restrictions apply to
2588 <tt class="LITERAL"><a href=
2589 "actions-file.html#CONTENT-TYPE-OVERWRITE">content-type-overwrite</a></tt>.
2590 <tt class="LITERAL">force-text-mode</tt> declares a document as
2591 text, without looking at the <span class=
2592 "QUOTE">"Content-Type:"</span> first.</p>
2594 <div class="WARNING">
2595 <table class="WARNING" border="1" width="90%">
2597 <td class="c6" align="center">Warning</td>
2602 <p>Think twice before activating this action. Filtering
2603 binary data with regular expressions can cause file
2611 <dt>Example usage:</dt>
2614 <table class="c4" border="0" width="90%">
2617 <pre class="SCREEN">
2630 <h4 class="SECT3"><a name="FORWARD-OVERRIDE" id=
2631 "FORWARD-OVERRIDE">8.5.17. forward-override</a></h4>
2633 <div class="VARIABLELIST">
2635 <dt>Typical use:</dt>
2638 <p>Change the forwarding settings based on User-Agent or
2645 <p>Overrules the forward directives in the configuration
2660 <p><span class="QUOTE">"forward ."</span> to use a direct
2661 connection without any additional proxies.</p>
2665 <p><span class="QUOTE">"forward 127.0.0.1:8123"</span> to
2666 use the HTTP proxy listening at 127.0.0.1 port 8123.</p>
2670 <p><span class="QUOTE">"forward-socks4a 127.0.0.1:9050
2671 ."</span> to use the socks4a proxy listening at 127.0.0.1
2672 port 9050. Replace <span class=
2673 "QUOTE">"forward-socks4a"</span> with <span class=
2674 "QUOTE">"forward-socks4"</span> to use a socks4 connection
2675 (with local DNS resolution) instead, use <span class=
2676 "QUOTE">"forward-socks5"</span> for socks5 connections
2677 (with remote DNS resolution).</p>
2681 <p><span class="QUOTE">"forward-socks4a 127.0.0.1:9050
2682 proxy.example.org:8000"</span> to use the socks4a proxy
2683 listening at 127.0.0.1 port 9050 to reach the HTTP proxy
2684 listening at proxy.example.org port 8000. Replace
2685 <span class="QUOTE">"forward-socks4a"</span> with
2686 <span class="QUOTE">"forward-socks4"</span> to use a socks4
2687 connection (with local DNS resolution) instead, use
2688 <span class="QUOTE">"forward-socks5"</span> for socks5
2689 connections (with remote DNS resolution).</p>
2697 <p>This action takes parameters similar to the <a href=
2698 "config.html#FORWARDING">forward</a> directives in the
2699 configuration file, but without the URL pattern. It can be used
2700 as replacement, but normally it's only used in cases where
2701 matching based on the request URL isn't sufficient.</p>
2703 <div class="WARNING">
2704 <table class="WARNING" border="1" width="90%">
2706 <td class="c6" align="center">Warning</td>
2711 <p>Please read the description for the <a href=
2712 "config.html#FORWARDING">forward</a> directives before
2713 using this action. Forwarding to the wrong people will
2714 reduce your privacy and increase the chances of
2715 man-in-the-middle attacks.</p>
2717 <p>If the ports are missing or invalid, default values
2718 will be used. This might change in the future and you
2719 shouldn't rely on it. Otherwise incorrect syntax causes
2720 Privoxy to exit.</p>
2723 "http://config.privoxy.org/show-url-info" target=
2724 "_top">show-url-info CGI page</a> to verify that your
2725 forward settings do what you thought the do.</p>
2732 <dt>Example usage:</dt>
2735 <table class="c4" border="0" width="90%">
2738 <pre class="SCREEN">
2739 # Always use direct connections for requests previously tagged as
2740 # <span class="QUOTE">"User-Agent: fetch libfetch/2.0"</span> and make sure
2741 # resuming downloads continues to work.
2742 # This way you can continue to use Tor for your normal browsing,
2743 # without overloading the Tor network with your FreeBSD ports updates
2744 # or downloads of bigger files like ISOs.
2745 # Note that HTTP headers are easy to fake and therefore their
2746 # values are as (un)trustworthy as your clients and users.
2747 {+forward-override{forward .} \
2748 -hide-if-modified-since \
2749 -overwrite-last-modified \
2751 TAG:^User-Agent: fetch libfetch/2\.0$
2763 <h4 class="SECT3"><a name="HANDLE-AS-EMPTY-DOCUMENT" id=
2764 "HANDLE-AS-EMPTY-DOCUMENT">8.5.18. handle-as-empty-document</a></h4>
2766 <div class="VARIABLELIST">
2768 <dt>Typical use:</dt>
2771 <p>Mark URLs that should be replaced by empty documents
2772 <span class="emphasis EMPHASIS c2">if they get
2779 <p>This action alone doesn't do anything noticeable. It just
2780 marks URLs. If the <tt class="LITERAL"><a href=
2781 "actions-file.html#BLOCK">block</a></tt> action <span class=
2782 "emphasis EMPHASIS c2">also applies</span>, the presence or
2783 absence of this mark decides whether an HTML <span class=
2784 "QUOTE">"BLOCKED"</span> page, or an empty document will be
2785 sent to the client as a substitute for the blocked content. The
2786 <span class="emphasis EMPHASIS c2">empty</span> document isn't
2787 literally empty, but actually contains a single space.</p>
2805 <p>Some browsers complain about syntax errors if JavaScript
2806 documents are blocked with <span class=
2807 "APPLICATION">Privoxy's</span> default HTML page; this option
2808 can be used to silence them. And of course this action can also
2809 be used to eliminate the <span class=
2810 "APPLICATION">Privoxy</span> BLOCKED message in frames.</p>
2812 <p>The content type for the empty document can be specified
2813 with <tt class="LITERAL"><a href=
2814 "actions-file.html#CONTENT-TYPE-OVERWRITE">content-type-overwrite{}</a></tt>,
2815 but usually this isn't necessary.</p>
2818 <dt>Example usage:</dt>
2821 <table class="c4" border="0" width="90%">
2824 <pre class="SCREEN">
2825 # Block all documents on example.org that end with ".js",
2826 # but send an empty document instead of the usual HTML message.
2827 {+block{Blocked JavaScript} +handle-as-empty-document}
2840 <h4 class="SECT3"><a name="HANDLE-AS-IMAGE" id=
2841 "HANDLE-AS-IMAGE">8.5.19. handle-as-image</a></h4>
2843 <div class="VARIABLELIST">
2845 <dt>Typical use:</dt>
2848 <p>Mark URLs as belonging to images (so they'll be replaced by
2849 images <span class="emphasis EMPHASIS c2">if they do get
2850 blocked</span>, rather than HTML pages)</p>
2856 <p>This action alone doesn't do anything noticeable. It just
2857 marks URLs as images. If the <tt class="LITERAL"><a href=
2858 "actions-file.html#BLOCK">block</a></tt> action <span class=
2859 "emphasis EMPHASIS c2">also applies</span>, the presence or
2860 absence of this mark decides whether an HTML <span class=
2861 "QUOTE">"blocked"</span> page, or a replacement image (as
2862 determined by the <tt class="LITERAL"><a href=
2863 "actions-file.html#SET-IMAGE-BLOCKER">set-image-blocker</a></tt>
2864 action) will be sent to the client as a substitute for the
2865 blocked content.</p>
2883 <p>The below generic example section is actually part of
2884 <tt class="FILENAME">default.action</tt>. It marks all URLs
2885 with well-known image file name extensions as images and should
2888 <p>Users will probably only want to use the handle-as-image
2889 action in conjunction with <tt class="LITERAL"><a href=
2890 "actions-file.html#BLOCK">block</a></tt>, to block sources of
2891 banners, whose URLs don't reflect the file type, like in the
2892 second example section.</p>
2894 <p>Note that you cannot treat HTML pages as images in most
2895 cases. For instance, (in-line) ad frames require an HTML page
2896 to be sent, or they won't display properly. Forcing <tt class=
2897 "LITERAL">handle-as-image</tt> in this situation will not
2898 replace the ad frame with an image, but lead to error
2902 <dt>Example usage (sections):</dt>
2905 <table class="c4" border="0" width="90%">
2908 <pre class="SCREEN">
2909 # Generic image extensions:
2912 /.*\.(gif|jpg|jpeg|png|bmp|ico)$
2914 # These don't look like images, but they're banners and should be
2915 # blocked as images:
2917 {+block{Nasty banners.} +handle-as-image}
2918 nasty-banner-server.example.com/junk.cgi\?output=trash
2929 <h4 class="SECT3"><a name="HIDE-ACCEPT-LANGUAGE" id=
2930 "HIDE-ACCEPT-LANGUAGE">8.5.20. hide-accept-language</a></h4>
2932 <div class="VARIABLELIST">
2934 <dt>Typical use:</dt>
2937 <p>Pretend to use different language settings.</p>
2943 <p>Deletes or replaces the <span class=
2944 "QUOTE">"Accept-Language:"</span> HTTP header in client
2951 <p>Parameterized.</p>
2957 <p>Keyword: <span class="QUOTE">"block"</span>, or any user
2964 <p>Faking the browser's language settings can be useful to make
2965 a foreign User-Agent set with <tt class="LITERAL"><a href=
2966 "actions-file.html#HIDE-USER-AGENT">hide-user-agent</a></tt>
2967 more believable.</p>
2969 <p>However some sites with content in different languages check
2970 the <span class="QUOTE">"Accept-Language:"</span> to decide
2971 which one to take by default. Sometimes it isn't possible to
2972 later switch to another language without changing the
2973 <span class="QUOTE">"Accept-Language:"</span> header first.</p>
2975 <p>Therefore it's a good idea to either only change the
2976 <span class="QUOTE">"Accept-Language:"</span> header to
2977 languages you understand, or to languages that aren't wide
2980 <p>Before setting the <span class=
2981 "QUOTE">"Accept-Language:"</span> header to a rare language,
2982 you should consider that it helps to make your requests unique
2983 and thus easier to trace. If you don't plan to change this
2984 header frequently, you should stick to a common language.</p>
2987 <dt>Example usage (section):</dt>
2990 <table class="c4" border="0" width="90%">
2993 <pre class="SCREEN">
2994 # Pretend to use Canadian language settings.
2995 {+hide-accept-language{en-ca} \
2996 +hide-user-agent{Mozilla/5.0 (X11; U; OpenBSD i386; en-CA; rv:1.8.0.4) Gecko/20060628 Firefox/1.5.0.4} \
3009 <h4 class="SECT3"><a name="HIDE-CONTENT-DISPOSITION" id=
3010 "HIDE-CONTENT-DISPOSITION">8.5.21. hide-content-disposition</a></h4>
3012 <div class="VARIABLELIST">
3014 <dt>Typical use:</dt>
3017 <p>Prevent download menus for content you prefer to view inside
3024 <p>Deletes or replaces the <span class=
3025 "QUOTE">"Content-Disposition:"</span> HTTP header set by some
3032 <p>Parameterized.</p>
3038 <p>Keyword: <span class="QUOTE">"block"</span>, or any user
3045 <p>Some servers set the <span class=
3046 "QUOTE">"Content-Disposition:"</span> HTTP header for documents
3047 they assume you want to save locally before viewing them. The
3048 <span class="QUOTE">"Content-Disposition:"</span> header
3049 contains the file name the browser is supposed to use by
3052 <p>In most browsers that understand this header, it makes it
3053 impossible to <span class="emphasis EMPHASIS c2">just
3054 view</span> the document, without downloading it first, even if
3055 it's just a simple text file or an image.</p>
3057 <p>Removing the <span class=
3058 "QUOTE">"Content-Disposition:"</span> header helps to prevent
3059 this annoyance, but some browsers additionally check the
3060 <span class="QUOTE">"Content-Type:"</span> header, before they
3061 decide if they can display a document without saving it first.
3062 In these cases, you have to change this header as well, before
3063 the browser stops displaying download menus.</p>
3065 <p>It is also possible to change the server's file name
3066 suggestion to another one, but in most cases it isn't worth the
3067 time to set it up.</p>
3069 <p>This action will probably be removed in the future, use
3070 server-header filters instead.</p>
3073 <dt>Example usage:</dt>
3076 <table class="c4" border="0" width="90%">
3079 <pre class="SCREEN">
3080 # Disarm the download link in Sourceforge's patch tracker
3082 +content-type-overwrite{text/plain}\
3083 +hide-content-disposition{block} }
3084 .sourceforge.net/tracker/download\.php
3095 <h4 class="SECT3"><a name="HIDE-IF-MODIFIED-SINCE" id=
3096 "HIDE-IF-MODIFIED-SINCE">8.5.22. hide-if-modified-since</a></h4>
3098 <div class="VARIABLELIST">
3100 <dt>Typical use:</dt>
3103 <p>Prevent yet another way to track the user's steps between
3110 <p>Deletes the <span class="QUOTE">"If-Modified-Since:"</span>
3111 HTTP client header or modifies its value.</p>
3117 <p>Parameterized.</p>
3123 <p>Keyword: <span class="QUOTE">"block"</span>, or a user
3124 defined value that specifies a range of hours.</p>
3130 <p>Removing this header is useful for filter testing, where you
3131 want to force a real reload instead of getting status code
3132 <span class="QUOTE">"304"</span>, which would cause the browser
3133 to use a cached copy of the page.</p>
3135 <p>Instead of removing the header, <tt class=
3136 "LITERAL">hide-if-modified-since</tt> can also add or subtract
3137 a random amount of time to/from the header's value. You specify
3138 a range of minutes where the random factor should be chosen
3139 from and <span class="APPLICATION">Privoxy</span> does the
3140 rest. A negative value means subtracting, a positive value
3143 <p>Randomizing the value of the <span class=
3144 "QUOTE">"If-Modified-Since:"</span> makes it less likely that
3145 the server can use the time as a cookie replacement, but you
3146 will run into caching problems if the random range is too
3149 <p>It is a good idea to only use a small negative value and let
3150 <tt class="LITERAL"><a href=
3151 "actions-file.html#OVERWRITE-LAST-MODIFIED">overwrite-last-modified</a></tt>
3152 handle the greater changes.</p>
3154 <p>It is also recommended to use this action together with
3155 <tt class="LITERAL"><a href=
3156 "actions-file.html#CRUNCH-IF-NONE-MATCH">crunch-if-none-match</a></tt>,
3157 otherwise it's more or less pointless.</p>
3160 <dt>Example usage (section):</dt>
3163 <table class="c4" border="0" width="90%">
3166 <pre class="SCREEN">
3167 # Let the browser revalidate but make tracking based on the time less likely.
3168 {+hide-if-modified-since{-60} \
3169 +overwrite-last-modified{randomize} \
3170 +crunch-if-none-match}
3182 <h4 class="SECT3"><a name="HIDE-FROM-HEADER" id=
3183 "HIDE-FROM-HEADER">8.5.23. hide-from-header</a></h4>
3185 <div class="VARIABLELIST">
3187 <dt>Typical use:</dt>
3190 <p>Keep your (old and ill) browser from telling web servers
3191 your email address</p>
3197 <p>Deletes any existing <span class="QUOTE">"From:"</span> HTTP
3198 header, or replaces it with the specified string.</p>
3204 <p>Parameterized.</p>
3210 <p>Keyword: <span class="QUOTE">"block"</span>, or any user
3217 <p>The keyword <span class="QUOTE">"block"</span> will
3218 completely remove the header (not to be confused with the
3219 <tt class="LITERAL"><a href=
3220 "actions-file.html#BLOCK">block</a></tt> action).</p>
3222 <p>Alternately, you can specify any value you prefer to be sent
3223 to the web server. If you do, it is a matter of fairness not to
3224 use any address that is actually used by a real person.</p>
3226 <p>This action is rarely needed, as modern web browsers don't
3227 send <span class="QUOTE">"From:"</span> headers anymore.</p>
3230 <dt>Example usage:</dt>
3233 <table class="c4" border="0" width="90%">
3236 <pre class="SCREEN">
3237 +hide-from-header{block}
3243 <table class="c4" border="0" width="90%">
3246 <pre class="SCREEN">
3247 +hide-from-header{spam-me-senseless@sittingduck.example.com}
3258 <h4 class="SECT3"><a name="HIDE-REFERRER" id="HIDE-REFERRER">8.5.24.
3259 hide-referrer</a></h4><a name="HIDE-REFERER" id="HIDE-REFERER"></a>
3261 <div class="VARIABLELIST">
3263 <dt>Typical use:</dt>
3266 <p>Conceal which link you followed to get to a particular
3273 <p>Deletes the <span class="QUOTE">"Referer:"</span> (sic) HTTP
3274 header from the client request, or replaces it with a forged
3281 <p>Parameterized.</p>
3289 <p><span class="QUOTE">"conditional-block"</span> to delete
3290 the header completely if the host has changed.</p>
3294 <p><span class="QUOTE">"conditional-forge"</span> to forge
3295 the header if the host has changed.</p>
3299 <p><span class="QUOTE">"block"</span> to delete the header
3300 unconditionally.</p>
3304 <p><span class="QUOTE">"forge"</span> to pretend to be
3305 coming from the homepage of the server we are talking
3310 <p>Any other string to set a user defined referrer.</p>
3318 <p><tt class="LITERAL">conditional-block</tt> is the only
3319 parameter, that isn't easily detected in the server's log file.
3320 If it blocks the referrer, the request will look like the
3321 visitor used a bookmark or typed in the address directly.</p>
3323 <p>Leaving the referrer unmodified for requests on the same
3324 host allows the server owner to see the visitor's <span class=
3325 "QUOTE">"click path"</span>, but in most cases she could also
3326 get that information by comparing other parts of the log file:
3327 for example the User-Agent if it isn't a very common one, or
3328 the user's IP address if it doesn't change between different
3331 <p>Always blocking the referrer, or using a custom one, can
3332 lead to failures on servers that check the referrer before they
3333 answer any requests, in an attempt to prevent their content
3334 from being embedded or linked to elsewhere.</p>
3336 <p>Both <tt class="LITERAL">conditional-block</tt> and
3337 <tt class="LITERAL">forge</tt> will work with referrer checks,
3338 as long as content and valid referring page are on the same
3339 host. Most of the time that's the case.</p>
3341 <p><tt class="LITERAL">hide-referer</tt> is an alternate
3342 spelling of <tt class="LITERAL">hide-referrer</tt> and the two
3343 can be can be freely substituted with each other. (<span class=
3344 "QUOTE">"referrer"</span> is the correct English spelling,
3345 however the HTTP specification has a bug - it requires it to be
3346 spelled as <span class="QUOTE">"referer"</span>.)</p>
3349 <dt>Example usage:</dt>
3352 <table class="c4" border="0" width="90%">
3355 <pre class="SCREEN">
3356 +hide-referrer{forge}
3362 <table class="c4" border="0" width="90%">
3365 <pre class="SCREEN">
3366 +hide-referrer{http://www.yahoo.com/}
3377 <h4 class="SECT3"><a name="HIDE-USER-AGENT" id=
3378 "HIDE-USER-AGENT">8.5.25. hide-user-agent</a></h4>
3380 <div class="VARIABLELIST">
3382 <dt>Typical use:</dt>
3385 <p>Try to conceal your type of browser and client operating
3392 <p>Replaces the value of the <span class=
3393 "QUOTE">"User-Agent:"</span> HTTP header in client requests
3394 with the specified value.</p>
3400 <p>Parameterized.</p>
3406 <p>Any user-defined string.</p>
3412 <div class="WARNING">
3413 <table class="WARNING" border="1" width="90%">
3415 <td class="c6" align="center">Warning</td>
3420 <p>This can lead to problems on web sites that depend
3421 on looking at this header in order to customize their
3422 content for different browsers (which, by the way, is
3423 <span class="emphasis EMPHASIS c2">NOT</span> the right
3424 thing to do: good web sites work
3425 browser-independently).</p>
3431 <p>Using this action in multi-user setups or wherever different
3432 types of browsers will access the same <span class=
3433 "APPLICATION">Privoxy</span> is <span class=
3434 "emphasis EMPHASIS c2">not recommended</span>. In single-user,
3435 single-browser setups, you might use it to delete your OS
3436 version information from the headers, because it is an
3437 invitation to exploit known bugs for your OS. It is also
3438 occasionally useful to forge this in order to access sites that
3439 won't let you in otherwise (though there may be a good reason
3442 <p>More information on known user-agent strings can be found at
3443 <a href="http://www.user-agents.org/" target=
3444 "_top">http://www.user-agents.org/</a> and <a href=
3445 "http://en.wikipedia.org/wiki/User_agent" target=
3446 "_top">http://en.wikipedia.org/wiki/User_agent</a>.</p>
3449 <dt>Example usage:</dt>
3452 <table class="c4" border="0" width="90%">
3455 <pre class="SCREEN">
3456 +hide-user-agent{Netscape 6.1 (X11; I; Linux 2.4.18 i686)}
3467 <h4 class="SECT3"><a name="LIMIT-CONNECT" id="LIMIT-CONNECT">8.5.26.
3468 limit-connect</a></h4>
3470 <div class="VARIABLELIST">
3472 <dt>Typical use:</dt>
3475 <p>Prevent abuse of <span class="APPLICATION">Privoxy</span> as
3476 a TCP proxy relay or disable SSL for untrusted sites</p>
3482 <p>Specifies to which ports HTTP CONNECT requests are
3489 <p>Parameterized.</p>
3495 <p>A comma-separated list of ports or port ranges (the latter
3496 using dashes, with the minimum defaulting to 0 and the maximum
3503 <p>By default, i.e. if no <tt class=
3504 "LITERAL">limit-connect</tt> action applies, <span class=
3505 "APPLICATION">Privoxy</span> allows HTTP CONNECT requests to
3506 all ports. Use <tt class="LITERAL">limit-connect</tt> if
3507 fine-grained control is desired for some or all
3510 <p>The CONNECT methods exists in HTTP to allow access to secure
3511 websites (<span class="QUOTE">"https://"</span> URLs) through
3512 proxies. It works very simply: the proxy connects to the server
3513 on the specified port, and then short-circuits its connections
3514 to the client and to the remote server. This means
3515 CONNECT-enabled proxies can be used as TCP relays very
3518 <p><span class="APPLICATION">Privoxy</span> relays HTTPS
3519 traffic without seeing the decoded content. Websites can
3520 leverage this limitation to circumvent <span class=
3521 "APPLICATION">Privoxy</span>'s filters. By specifying an
3522 invalid port range you can disable HTTPS entirely.</p>
3525 <dt>Example usages:</dt>
3528 <table class="c4" border="0" width="90%">
3531 <pre class="SCREEN">
3532 +limit-connect{443} # Port 443 is OK.
3533 +limit-connect{80,443} # Ports 80 and 443 are OK.
3534 +limit-connect{-3, 7, 20-100, 500-} # Ports less than 3, 7, 20 to 100 and above 500 are OK.
3535 +limit-connect{-} # All ports are OK
3536 +limit-connect{,} # No HTTPS/SSL traffic is allowed
3547 <h4 class="SECT3"><a name="PREVENT-COMPRESSION" id=
3548 "PREVENT-COMPRESSION">8.5.27. prevent-compression</a></h4>
3550 <div class="VARIABLELIST">
3552 <dt>Typical use:</dt>
3555 <p>Ensure that servers send the content uncompressed, so it can
3556 be passed through <tt class="LITERAL"><a href=
3557 "actions-file.html#FILTER">filter</a></tt>s.</p>
3563 <p>Removes the Accept-Encoding header which can be used to ask
3564 for compressed transfer.</p>
3582 <p>More and more websites send their content compressed by
3583 default, which is generally a good idea and saves bandwidth.
3584 But the <tt class="LITERAL"><a href=
3585 "actions-file.html#FILTER">filter</a></tt> and <tt class=
3587 "actions-file.html#DEANIMATE-GIFS">deanimate-gifs</a></tt>
3588 actions need access to the uncompressed data.</p>
3590 <p>When compiled with zlib support (available since
3591 <span class="APPLICATION">Privoxy</span> 3.0.7), content that
3592 should be filtered is decompressed on-the-fly and you don't
3593 have to worry about this action. If you are using an older
3594 <span class="APPLICATION">Privoxy</span> version, or one that
3595 hasn't been compiled with zlib support, this action can be used
3596 to convince the server to send the content uncompressed.</p>
3598 <p>Most text-based instances compress very well, the size is
3599 seldom decreased by less than 50%, for markup-heavy instances
3600 like news feeds saving more than 90% of the original size isn't
3603 <p>Not using compression will therefore slow down the transfer,
3604 and you should only enable this action if you really need it.
3605 As of <span class="APPLICATION">Privoxy</span> 3.0.7 it's
3606 disabled in all predefined action settings.</p>
3608 <p>Note that some (rare) ill-configured sites don't handle
3609 requests for uncompressed documents correctly. Broken PHP
3610 applications tend to send an empty document body, some IIS
3611 versions only send the beginning of the content. If you enable
3612 <tt class="LITERAL">prevent-compression</tt> per default, you
3613 might want to add exceptions for those sites. See the example
3614 for how to do that.</p>
3617 <dt>Example usage (sections):</dt>
3620 <table class="c4" border="0" width="90%">
3623 <pre class="SCREEN">
3624 # Selectively turn off compression, and enable a filter
3626 { +filter{tiny-textforms} +prevent-compression }
3627 # Match only these sites
3632 # Or instead, we could set a universal default:
3634 { +prevent-compression }
3637 # Then maybe make exceptions for broken sites:
3639 { -prevent-compression }
3651 <h4 class="SECT3"><a name="OVERWRITE-LAST-MODIFIED" id=
3652 "OVERWRITE-LAST-MODIFIED">8.5.28. overwrite-last-modified</a></h4>
3654 <div class="VARIABLELIST">
3656 <dt>Typical use:</dt>
3659 <p>Prevent yet another way to track the user's steps between
3666 <p>Deletes the <span class="QUOTE">"Last-Modified:"</span> HTTP
3667 server header or modifies its value.</p>
3673 <p>Parameterized.</p>
3679 <p>One of the keywords: <span class="QUOTE">"block"</span>,
3680 <span class="QUOTE">"reset-to-request-time"</span> and
3681 <span class="QUOTE">"randomize"</span></p>
3687 <p>Removing the <span class="QUOTE">"Last-Modified:"</span>
3688 header is useful for filter testing, where you want to force a
3689 real reload instead of getting status code <span class=
3690 "QUOTE">"304"</span>, which would cause the browser to reuse
3691 the old version of the page.</p>
3693 <p>The <span class="QUOTE">"randomize"</span> option overwrites
3694 the value of the <span class="QUOTE">"Last-Modified:"</span>
3695 header with a randomly chosen time between the original value
3696 and the current time. In theory the server could send each
3697 document with a different <span class=
3698 "QUOTE">"Last-Modified:"</span> header to track visits without
3699 using cookies. <span class="QUOTE">"Randomize"</span> makes it
3700 impossible and the browser can still revalidate cached
3703 <p><span class="QUOTE">"reset-to-request-time"</span>
3704 overwrites the value of the <span class=
3705 "QUOTE">"Last-Modified:"</span> header with the current time.
3706 You could use this option together with <tt class=
3708 "actions-file.html#HIDE-IF-MODIFIED-SINCE">hide-if-modified-since</a></tt>
3709 to further customize your random range.</p>
3711 <p>The preferred parameter here is <span class=
3712 "QUOTE">"randomize"</span>. It is safe to use, as long as the
3713 time settings are more or less correct. If the server sets the
3714 <span class="QUOTE">"Last-Modified:"</span> header to the time
3715 of the request, the random range becomes zero and the value
3716 stays the same. Therefore you should later randomize it a
3717 second time with <tt class="LITERAL"><a href=
3718 "actions-file.html#HIDE-IF-MODIFIED-SINCE">hided-if-modified-since</a></tt>,
3719 just to be sure.</p>
3721 <p>It is also recommended to use this action together with
3722 <tt class="LITERAL"><a href=
3723 "actions-file.html#CRUNCH-IF-NONE-MATCH">crunch-if-none-match</a></tt>.</p>
3726 <dt>Example usage:</dt>
3729 <table class="c4" border="0" width="90%">
3732 <pre class="SCREEN">
3733 # Let the browser revalidate without being tracked across sessions
3734 { +hide-if-modified-since{-60} \
3735 +overwrite-last-modified{randomize} \
3736 +crunch-if-none-match}
3748 <h4 class="SECT3"><a name="REDIRECT" id="REDIRECT">8.5.29.
3751 <div class="VARIABLELIST">
3753 <dt>Typical use:</dt>
3756 <p>Redirect requests to other sites.</p>
3762 <p>Convinces the browser that the requested document has been
3763 moved to another location and the browser should get it from
3770 <p>Parameterized</p>
3776 <p>An absolute URL or a single pcrs command.</p>
3782 <p>Requests to which this action applies are answered with a
3783 HTTP redirect to URLs of your choosing. The new URL is either
3784 provided as parameter, or derived by applying a single pcrs
3785 command to the original URL.</p>
3787 <p>This action will be ignored if you use it together with
3788 <tt class="LITERAL"><a href=
3789 "actions-file.html#BLOCK">block</a></tt>. It can be combined
3790 with <tt class="LITERAL"><a href=
3791 "actions-file.html#FAST-REDIRECTS">fast-redirects{check-decoded-url}</a></tt>
3792 to redirect to a decoded version of a rewritten URL.</p>
3794 <p>Use this action carefully, make sure not to create
3795 redirection loops and be aware that using your own redirects
3796 might make it possible to fingerprint your requests.</p>
3798 <p>In case of problems with your redirects, or simply to watch
3799 them working, enable <a href="config.html#DEBUG">debug
3803 <dt>Example usages:</dt>
3806 <table class="c4" border="0" width="90%">
3809 <pre class="SCREEN">
3810 # Replace example.com's style sheet with another one
3811 { +redirect{http://localhost/css-replacements/example.com.css} }
3812 example.com/stylesheet\.css
3814 # Create a short, easy to remember nickname for a favorite site
3815 # (relies on the browser accept and forward invalid URLs to <span class=
3816 "APPLICATION">Privoxy</span>)
3817 { +redirect{http://www.privoxy.org/user-manual/actions-file.html} }
3820 # Always use the expanded view for Undeadly.org articles
3821 # (Note the $ at the end of the URL pattern to make sure
3822 # the request for the rewritten URL isn't redirected as well)
3823 {+redirect{s@$@&mode=expanded@}}
3824 undeadly.org/cgi\?action=article&sid=\d*$
3826 # Redirect Google search requests to MSN
3827 {+redirect{s@^http://[^/]*/search\?q=([^&]*).*@http://search.msn.com/results.aspx?q=$1@}}
3830 # Redirect MSN search requests to Yahoo
3831 {+redirect{s@^http://[^/]*/results\.aspx\?q=([^&]*).*@http://search.yahoo.com/search?p=$1@}}
3832 search.msn.com//results\.aspx\?q=
3834 # Redirect remote requests for this manual
3835 # to the local version delivered by Privoxy
3836 {+redirect{s@^http://www@http://config@}}
3837 www.privoxy.org/user-manual/
3848 <h4 class="SECT3"><a name="SERVER-HEADER-FILTER" id=
3849 "SERVER-HEADER-FILTER">8.5.30. server-header-filter</a></h4>
3851 <div class="VARIABLELIST">
3853 <dt>Typical use:</dt>
3856 <p>Rewrite or remove single server headers.</p>
3862 <p>All server headers to which this action applies are filtered
3863 on-the-fly through the specified regular expression based
3870 <p>Parameterized.</p>
3876 <p>The name of a server-header filter, as defined in one of the
3877 <a href="filter-file.html">filter files</a>.</p>
3883 <p>Server-header filters are applied to each header on its own,
3884 not to all at once. This makes it easier to diagnose problems,
3885 but on the downside you can't write filters that only change
3886 header x if header y's value is z. You can do that by using
3889 <p>Server-header filters are executed after the other header
3890 actions have finished and use their output as input.</p>
3892 <p>Please refer to the <a href="filter-file.html">filter file
3893 chapter</a> to learn which server-header filters are available
3894 by default, and how to create your own.</p>
3897 <dt>Example usage (section):</dt>
3900 <table class="c4" border="0" width="90%">
3903 <pre class="SCREEN">
3904 {+server-header-filter{html-to-xml}}
3905 example.org/xml-instance-that-is-delivered-as-html
3907 {+server-header-filter{xml-to-html}}
3908 example.org/instance-that-is-delivered-as-xml-but-is-not
3920 <h4 class="SECT3"><a name="SERVER-HEADER-TAGGER" id=
3921 "SERVER-HEADER-TAGGER">8.5.31. server-header-tagger</a></h4>
3923 <div class="VARIABLELIST">
3925 <dt>Typical use:</dt>
3928 <p>Enable or disable filters based on the Content-Type
3935 <p>Server headers to which this action applies are filtered
3936 on-the-fly through the specified regular expression based
3937 substitutions, the result is used as tag.</p>
3943 <p>Parameterized.</p>
3949 <p>The name of a server-header tagger, as defined in one of the
3950 <a href="filter-file.html">filter files</a>.</p>
3956 <p>Server-header taggers are applied to each header on its own,
3957 and as the header isn't modified, each tagger <span class=
3958 "QUOTE">"sees"</span> the original.</p>
3960 <p>Server-header taggers are executed before all other header
3961 actions that modify server headers. Their tags can be used to
3962 control all of the other server-header actions, the content
3963 filters and the crunch actions (<a href=
3964 "actions-file.html#REDIRECT">redirect</a> and <a href=
3965 "actions-file.html#BLOCK">block</a>).</p>
3967 <p>Obviously crunching based on tags created by server-header
3968 taggers doesn't prevent the request from showing up in the
3969 server's log file.</p>
3972 <dt>Example usage (section):</dt>
3975 <table class="c4" border="0" width="90%">
3978 <pre class="SCREEN">
3979 # Tag every request with the content type declared by the server
3980 {+server-header-tagger{content-type}}
3993 <h4 class="SECT3"><a name="SESSION-COOKIES-ONLY" id=
3994 "SESSION-COOKIES-ONLY">8.5.32. session-cookies-only</a></h4>
3996 <div class="VARIABLELIST">
3998 <dt>Typical use:</dt>
4001 <p>Allow only temporary <span class="QUOTE">"session"</span>
4002 cookies (for the current browser session <span class=
4003 "emphasis EMPHASIS c2">only</span>).</p>
4009 <p>Deletes the <span class="QUOTE">"expires"</span> field from
4010 <span class="QUOTE">"Set-Cookie:"</span> server headers. Most
4011 browsers will not store such cookies permanently and forget
4012 them in between sessions.</p>
4030 <p>This is less strict than <tt class="LITERAL"><a href=
4031 "actions-file.html#CRUNCH-INCOMING-COOKIES">crunch-incoming-cookies</a></tt>
4032 / <tt class="LITERAL"><a href=
4033 "actions-file.html#CRUNCH-OUTGOING-COOKIES">crunch-outgoing-cookies</a></tt>
4034 and allows you to browse websites that insist or rely on
4035 setting cookies, without compromising your privacy too
4038 <p>Most browsers will not permanently store cookies that have
4039 been processed by <tt class="LITERAL">session-cookies-only</tt>
4040 and will forget about them between sessions. This makes
4041 profiling cookies useless, but won't break sites which require
4042 cookies so that you can log in for transactions. This is
4043 generally turned on for all sites, and is the recommended
4046 <p>It makes <span class="emphasis EMPHASIS c2">no sense at
4047 all</span> to use <tt class="LITERAL">session-cookies-only</tt>
4048 together with <tt class="LITERAL"><a href=
4049 "actions-file.html#CRUNCH-INCOMING-COOKIES">crunch-incoming-cookies</a></tt>
4050 or <tt class="LITERAL"><a href=
4051 "actions-file.html#CRUNCH-OUTGOING-COOKIES">crunch-outgoing-cookies</a></tt>.
4052 If you do, cookies will be plainly killed.</p>
4054 <p>Note that it is up to the browser how it handles such
4055 cookies without an <span class="QUOTE">"expires"</span> field.
4056 If you use an exotic browser, you might want to try it out to
4059 <p>This setting also has no effect on cookies that may have
4060 been stored previously by the browser before starting
4061 <span class="APPLICATION">Privoxy</span>. These would have to
4062 be removed manually.</p>
4064 <p><span class="APPLICATION">Privoxy</span> also uses the
4066 "actions-file.html#FILTER-CONTENT-COOKIES">content-cookies
4067 filter</a> to block some types of cookies. Content cookies are
4068 not effected by <tt class=
4069 "LITERAL">session-cookies-only</tt>.</p>
4072 <dt>Example usage:</dt>
4075 <table class="c4" border="0" width="90%">
4078 <pre class="SCREEN">
4079 +session-cookies-only
4090 <h4 class="SECT3"><a name="SET-IMAGE-BLOCKER" id=
4091 "SET-IMAGE-BLOCKER">8.5.33. set-image-blocker</a></h4>
4093 <div class="VARIABLELIST">
4095 <dt>Typical use:</dt>
4098 <p>Choose the replacement for blocked images</p>
4104 <p>This action alone doesn't do anything noticeable. If
4105 <span class="emphasis EMPHASIS c2">both</span> <tt class=
4106 "LITERAL"><a href="actions-file.html#BLOCK">block</a></tt>
4107 <span class="emphasis EMPHASIS c2">and</span> <tt class=
4109 "actions-file.html#HANDLE-AS-IMAGE">handle-as-image</a></tt>
4110 <span class="emphasis EMPHASIS c2">also</span> apply, i.e. if
4111 the request is to be blocked as an image, <span class=
4112 "emphasis EMPHASIS c2">then</span> the parameter of this action
4113 decides what will be sent as a replacement.</p>
4119 <p>Parameterized.</p>
4127 <p><span class="QUOTE">"pattern"</span> to send a built-in
4128 checkerboard pattern image. The image is visually decent,
4129 scales very well, and makes it obvious where banners were
4134 <p><span class="QUOTE">"blank"</span> to send a built-in
4135 transparent image. This makes banners disappear completely,
4136 but makes it hard to detect where <span class=
4137 "APPLICATION">Privoxy</span> has blocked images on a given
4138 page and complicates troubleshooting if <span class=
4139 "APPLICATION">Privoxy</span> has blocked innocent images,
4140 like navigation icons.</p>
4144 <p><span class="QUOTE">"<tt class=
4145 "REPLACEABLE c5">target-url</tt>"</span> to send a redirect
4146 to <tt class="REPLACEABLE c5">target-url</tt>. You can
4147 redirect to any image anywhere, even in your local
4148 filesystem via <span class="QUOTE">"file:///"</span> URL.
4149 (But note that not all browsers support redirecting to a
4150 local file system).</p>
4152 <p>A good application of redirects is to use special
4153 <span class="APPLICATION">Privoxy</span>-built-in URLs,
4154 which send the built-in images, as <tt class=
4155 "REPLACEABLE c5">target-url</tt>. This has the same visual
4156 effect as specifying <span class="QUOTE">"blank"</span> or
4157 <span class="QUOTE">"pattern"</span> in the first place,
4158 but enables your browser to cache the replacement image,
4159 instead of requesting it over and over again.</p>
4167 <p>The URLs for the built-in images are <span class=
4168 "QUOTE">"http://config.privoxy.org/send-banner?type=<tt class=
4169 "REPLACEABLE c5">type</tt>"</span>, where <tt class=
4170 "REPLACEABLE c5">type</tt> is either <span class=
4171 "QUOTE">"blank"</span> or <span class=
4172 "QUOTE">"pattern"</span>.</p>
4174 <p>There is a third (advanced) type, called <span class=
4175 "QUOTE">"auto"</span>. It is <span class=
4176 "emphasis EMPHASIS c2">NOT</span> to be used in <tt class=
4177 "LITERAL">set-image-blocker</tt>, but meant for use from
4178 <a href="filter-file.html">filters</a>. Auto will select the
4179 type of image that would have applied to the referring page,
4180 had it been an image.</p>
4183 <dt>Example usage:</dt>
4186 <p>Built-in pattern:</p>
4188 <table class="c4" border="0" width="90%">
4191 <pre class="SCREEN">
4192 +set-image-blocker{pattern}
4198 <p>Redirect to the BSD daemon:</p>
4200 <table class="c4" border="0" width="90%">
4203 <pre class="SCREEN">
4204 +set-image-blocker{http://www.freebsd.org/gifs/dae_up3.gif}
4210 <p>Redirect to the built-in pattern for better caching:</p>
4212 <table class="c4" border="0" width="90%">
4215 <pre class="SCREEN">
4216 +set-image-blocker{http://config.privoxy.org/send-banner?type=pattern}
4227 <h3 class="SECT3"><a name="AEN4725" id="AEN4725">8.5.34.
4230 <p>Note that many of these actions have the potential to cause a page
4231 to misbehave, possibly even not to display at all. There are many
4232 ways a site designer may choose to design his site, and what HTTP
4233 header content, and other criteria, he may depend on. There is no way
4234 to have hard and fast rules for all sites. See the <a href=
4235 "appendix.html#ACTIONSANAT">Appendix</a> for a brief example on
4236 troubleshooting actions.</p>
4241 <h2 class="SECT2"><a name="ALIASES" id="ALIASES">8.6. Aliases</a></h2>
4243 <p>Custom <span class="QUOTE">"actions"</span>, known to <span class=
4244 "APPLICATION">Privoxy</span> as <span class="QUOTE">"aliases"</span>,
4245 can be defined by combining other actions. These can in turn be invoked
4246 just like the built-in actions. Currently, an alias name can contain
4247 any character except space, tab, <span class="QUOTE">"="</span>,
4248 <span class="QUOTE">"{"</span> and <span class="QUOTE">"}"</span>, but
4249 we <span class="emphasis EMPHASIS c2">strongly recommend</span> that
4250 you only use <span class="QUOTE">"a"</span> to <span class=
4251 "QUOTE">"z"</span>, <span class="QUOTE">"0"</span> to <span class=
4252 "QUOTE">"9"</span>, <span class="QUOTE">"+"</span>, and <span class=
4253 "QUOTE">"-"</span>. Alias names are not case sensitive, and are not
4254 required to start with a <span class="QUOTE">"+"</span> or <span class=
4255 "QUOTE">"-"</span> sign, since they are merely textually expanded.</p>
4257 <p>Aliases can be used throughout the actions file, but they
4258 <span class="emphasis EMPHASIS c2">must be defined in a special section
4259 at the top of the file!</span> And there can only be one such section
4260 per actions file. Each actions file may have its own alias section, and
4261 the aliases defined in it are only visible within that file.</p>
4263 <p>There are two main reasons to use aliases: One is to save typing for
4264 frequently used combinations of actions, the other one is a gain in
4265 flexibility: If you decide once how you want to handle shops by
4266 defining an alias called <span class="QUOTE">"shop"</span>, you can
4267 later change your policy on shops in <span class=
4268 "emphasis EMPHASIS c2">one</span> place, and your changes will take
4269 effect everywhere in the actions file where the <span class=
4270 "QUOTE">"shop"</span> alias is used. Calling aliases by their purpose
4271 also makes your actions files more readable.</p>
4273 <p>Currently, there is one big drawback to using aliases, though:
4274 <span class="APPLICATION">Privoxy</span>'s built-in web-based action
4275 file editor honors aliases when reading the actions files, but it
4276 expands them before writing. So the effects of your aliases are of
4277 course preserved, but the aliases themselves are lost when you edit
4278 sections that use aliases with it.</p>
4280 <p>Now let's define some aliases...</p>
4282 <table class="c4" border="0" width="100%">
4285 <pre class="SCREEN">
4286 # Useful custom aliases we can use later.
4288 # Note the (required!) section header line and that this section
4289 # must be at the top of the actions file!
4293 # These aliases just save typing later:
4294 # (Note that some already use other aliases!)
4296 +crunch-all-cookies = +<a href=
4297 "actions-file.html#CRUNCH-INCOMING-COOKIES">crunch-incoming-cookies</a> +<a href="actions-file.html#CRUNCH-OUTGOING-COOKIES">crunch-outgoing-cookies</a>
4298 -crunch-all-cookies = -<a href=
4299 "actions-file.html#CRUNCH-INCOMING-COOKIES">crunch-incoming-cookies</a> -<a href="actions-file.html#CRUNCH-OUTGOING-COOKIES">crunch-outgoing-cookies</a>
4300 +block-as-image = +block{Blocked image.} +handle-as-image
4301 allow-all-cookies = -crunch-all-cookies -<a href=
4302 "actions-file.html#SESSION-COOKIES-ONLY">session-cookies-only</a> -<a href=
4303 "actions-file.html#FILTER-CONTENT-COOKIES">filter{content-cookies}</a>
4305 # These aliases define combinations of actions
4306 # that are useful for certain types of sites:
4308 fragile = -<a href="actions-file.html#BLOCK">block</a> -<a href=
4309 "actions-file.html#FILTER">filter</a> -crunch-all-cookies -<a href=
4310 "actions-file.html#FAST-REDIRECTS">fast-redirects</a> -<a href=
4311 "actions-file.html#HIDE-REFERER">hide-referrer</a> -<a href=
4312 "actions-file.html#PREVENT-COMPRESSION">prevent-compression</a>
4314 shop = -crunch-all-cookies -<a href=
4315 "actions-file.html#FILTER-ALL-POPUPS">filter{all-popups}</a>
4317 # Short names for other aliases, for really lazy people ;-)
4319 c0 = +crunch-all-cookies
4320 c1 = -crunch-all-cookies
4326 <p>...and put them to use. These sections would appear in the lower
4327 part of an actions file and define exceptions to the default actions
4328 (as specified further up for the <span class="QUOTE">"/"</span>
4331 <table class="c4" border="0" width="100%">
4334 <pre class="SCREEN">
4335 # These sites are either very complex or very keen on
4336 # user data and require minimal interference to work:
4339 .office.microsoft.com
4340 .windowsupdate.microsoft.com
4341 # Gmail is really mail.google.com, not gmail.com
4345 # Allow cookies (for setting and retrieving your customer data)
4349 .worldpay.com # for quietpc.com
4352 # These shops require pop-ups:
4354 {-filter{all-popups} -filter{unsolicited-popups}}
4362 <p>Aliases like <span class="QUOTE">"shop"</span> and <span class=
4363 "QUOTE">"fragile"</span> are typically used for <span class=
4364 "QUOTE">"problem"</span> sites that require more than one action to be
4365 disabled in order to function properly.</p>
4369 <h2 class="SECT2"><a name="ACT-EXAMPLES" id="ACT-EXAMPLES">8.7. Actions
4370 Files Tutorial</a></h2>
4372 <p>The above chapters have shown <a href="actions-file.html">which
4373 actions files there are and how they are organized</a>, how actions are
4374 <a href="actions-file.html#ACTIONS">specified</a> and <a href=
4375 "actions-file.html#ACTIONS-APPLY">applied to URLs</a>, how <a href=
4376 "actions-file.html#AF-PATTERNS">patterns</a> work, and how to define
4377 and use <a href="actions-file.html#ALIASES">aliases</a>. Now, let's
4378 look at an example <tt class="FILENAME">match-all.action</tt>,
4379 <tt class="FILENAME">default.action</tt> and <tt class=
4380 "FILENAME">user.action</tt> file and see how all these pieces come
4384 <h3 class="SECT3"><a name="AEN4789" id="AEN4789">8.7.1.
4385 match-all.action</a></h3>
4387 <p>Remember <span class="emphasis EMPHASIS c2">all actions are
4388 disabled when matching starts</span>, so we have to explicitly enable
4389 the ones we want.</p>
4391 <p>While the <tt class="FILENAME">match-all.action</tt> file only
4392 contains a single section, it is probably the most important one. It
4393 has only one pattern, <span class="QUOTE">"<tt class=
4394 "LITERAL">/</tt>"</span>, but this pattern <a href=
4395 "actions-file.html#AF-PATTERNS">matches all URLs</a>. Therefore, the
4396 set of actions used in this <span class="QUOTE">"default"</span>
4397 section <span class="emphasis EMPHASIS c2">will be applied to all
4398 requests as a start</span>. It can be partly or wholly overridden by
4399 other actions files like <tt class="FILENAME">default.action</tt> and
4400 <tt class="FILENAME">user.action</tt>, but it will still be largely
4401 responsible for your overall browsing experience.</p>
4403 <p>Again, at the start of matching, all actions are disabled, so
4404 there is no need to disable any actions here. (Remember: a
4405 <span class="QUOTE">"+"</span> preceding the action name enables the
4406 action, a <span class="QUOTE">"-"</span> disables!). Also note how
4407 this long line has been made more readable by splitting it into
4408 multiple lines with line continuation.</p>
4410 <table class="c4" border="0" width="100%">
4413 <pre class="SCREEN">
4416 "actions-file.html#CHANGE-X-FORWARDED-FOR">change-x-forwarded-for{block}</a> \
4417 +<a href="actions-file.html#HIDE-FROM-HEADER">hide-from-header{block}</a> \
4419 "actions-file.html#SET-IMAGE-BLOCKER">set-image-blocker{pattern}</a> \
4428 <p>The default behavior is now set.</p>
4432 <h3 class="SECT3"><a name="AEN4811" id="AEN4811">8.7.2.
4433 default.action</a></h3>
4435 <p>If you aren't a developer, there's no need for you to edit the
4436 <tt class="FILENAME">default.action</tt> file. It is maintained by
4437 the <span class="APPLICATION">Privoxy</span> developers and if you
4438 disagree with some of the sections, you should overrule them in your
4439 <tt class="FILENAME">user.action</tt>.</p>
4441 <p>Understanding the <tt class="FILENAME">default.action</tt> file
4442 can help you with your <tt class="FILENAME">user.action</tt>,
4445 <p>The first section in this file is a special section for internal
4446 use that prevents older <span class="APPLICATION">Privoxy</span>
4447 versions from reading the file:</p>
4449 <table class="c4" border="0" width="100%">
4452 <pre class="SCREEN">
4453 ##########################################################################
4454 # Settings -- Don't change! For internal Privoxy use ONLY.
4455 ##########################################################################
4457 for-privoxy-version=3.0.11
4463 <p>After that comes the (optional) alias section. We'll use the
4464 example section from the above <a href=
4465 "actions-file.html#ALIASES">chapter on aliases</a>, that also
4466 explains why and how aliases are used:</p>
4468 <table class="c4" border="0" width="100%">
4471 <pre class="SCREEN">
4472 ##########################################################################
4474 ##########################################################################
4477 # These aliases just save typing later:
4478 # (Note that some already use other aliases!)
4480 +crunch-all-cookies = +<a href=
4481 "actions-file.html#CRUNCH-INCOMING-COOKIES">crunch-incoming-cookies</a> +<a href="actions-file.html#CRUNCH-OUTGOING-COOKIES">crunch-outgoing-cookies</a>
4482 -crunch-all-cookies = -<a href=
4483 "actions-file.html#CRUNCH-INCOMING-COOKIES">crunch-incoming-cookies</a> -<a href="actions-file.html#CRUNCH-OUTGOING-COOKIES">crunch-outgoing-cookies</a>
4484 +block-as-image = +block{Blocked image.} +handle-as-image
4485 mercy-for-cookies = -crunch-all-cookies -<a href=
4486 "actions-file.html#SESSION-COOKIES-ONLY">session-cookies-only</a> -<a href=
4487 "actions-file.html#FILTER-CONTENT-COOKIES">filter{content-cookies}</a>
4489 # These aliases define combinations of actions
4490 # that are useful for certain types of sites:
4492 fragile = -<a href="actions-file.html#BLOCK">block</a> -<a href=
4493 "actions-file.html#FILTER">filter</a> -crunch-all-cookies -<a href=
4494 "actions-file.html#FAST-REDIRECTS">fast-redirects</a> -<a href=
4495 "actions-file.html#HIDE-REFERER">hide-referrer</a>
4496 shop = -crunch-all-cookies -<a href=
4497 "actions-file.html#FILTER-ALL-POPUPS">filter{all-popups}</a>
4503 <p>The first of our specialized sections is concerned with
4504 <span class="QUOTE">"fragile"</span> sites, i.e. sites that require
4505 minimum interference, because they are either very complex or very
4506 keen on tracking you (and have mechanisms in place that make them
4507 unusable for people who avoid being tracked). We will simply use our
4508 pre-defined <tt class="LITERAL">fragile</tt> alias instead of stating
4509 the list of actions explicitly:</p>
4511 <table class="c4" border="0" width="100%">
4514 <pre class="SCREEN">
4515 ##########################################################################
4516 # Exceptions for sites that'll break under the default action set:
4517 ##########################################################################
4519 # "Fragile" Use a minimum set of actions for these sites (see alias above):
4522 .office.microsoft.com # surprise, surprise!
4523 .windowsupdate.microsoft.com
4530 <p>Shopping sites are not as fragile, but they typically require
4531 cookies to log in, and pop-up windows for shopping carts or item
4532 details. Again, we'll use a pre-defined alias:</p>
4534 <table class="c4" border="0" width="100%">
4537 <pre class="SCREEN">
4542 .worldpay.com # for quietpc.com
4550 <p>The <tt class="LITERAL"><a href=
4551 "actions-file.html#FAST-REDIRECTS">fast-redirects</a></tt> action,
4552 which may have been enabled in <tt class=
4553 "FILENAME">match-all.action</tt>, breaks some sites. So disable it
4554 for popular sites where we know it misbehaves:</p>
4556 <table class="c4" border="0" width="100%">
4559 <pre class="SCREEN">
4560 { -<a href="actions-file.html#FAST-REDIRECTS">fast-redirects</a> }
4564 .altavista.com/.*(like|url|link):http
4565 .altavista.com/trans.*urltext=http
4572 <p>It is important that <span class="APPLICATION">Privoxy</span>
4573 knows which URLs belong to images, so that <span class=
4574 "emphasis EMPHASIS c2">if</span> they are to be blocked, a substitute
4575 image can be sent, rather than an HTML page. Contacting the remote
4576 site to find out is not an option, since it would destroy the loading
4577 time advantage of banner blocking, and it would feed the advertisers
4578 information about you. We can mark any URL as an image with the
4579 <tt class="LITERAL"><a href=
4580 "actions-file.html#HANDLE-AS-IMAGE">handle-as-image</a></tt> action,
4581 and marking all URLs that end in a known image file extension is a
4584 <table class="c4" border="0" width="100%">
4587 <pre class="SCREEN">
4588 ##########################################################################
4590 ##########################################################################
4592 # Define which file types will be treated as images, in case they get
4593 # blocked further down this file:
4595 { +<a href="actions-file.html#HANDLE-AS-IMAGE">handle-as-image</a> }
4596 /.*\.(gif|jpe?g|png|bmp|ico)$
4602 <p>And then there are known banner sources. They often use scripts to
4603 generate the banners, so it won't be visible from the URL that the
4604 request is for an image. Hence we block them <span class=
4605 "emphasis EMPHASIS c2">and</span> mark them as images in one go, with
4606 the help of our <tt class="LITERAL">+block-as-image</tt> alias
4607 defined above. (We could of course just as well use <tt class=
4608 "LITERAL">+<a href="actions-file.html#BLOCK">block</a> +<a href=
4609 "actions-file.html#HANDLE-AS-IMAGE">handle-as-image</a></tt> here.)
4610 Remember that the type of the replacement image is chosen by the
4611 <tt class="LITERAL"><a href=
4612 "actions-file.html#SET-IMAGE-BLOCKER">set-image-blocker</a></tt>
4613 action. Since all URLs have matched the default section with its
4614 <tt class="LITERAL">+<a href=
4615 "actions-file.html#SET-IMAGE-BLOCKER">set-image-blocker</a>{pattern}</tt>
4616 action before, it still applies and needn't be repeated:</p>
4618 <table class="c4" border="0" width="100%">
4621 <pre class="SCREEN">
4622 # Known ad generators:
4627 .ad.*.doubleclick.net
4628 .a.yimg.com/(?:(?!/i/).)*$
4629 .a[0-9].yimg.com/(?:(?!/i/).)*$
4637 <p>One of the most important jobs of <span class=
4638 "APPLICATION">Privoxy</span> is to block banners. Many of these can
4639 be <span class="QUOTE">"blocked"</span> by the <tt class=
4641 "actions-file.html#FILTER">filter</a>{banners-by-size}</tt> action,
4642 which we enabled above, and which deletes the references to banner
4643 images from the pages while they are loaded, so the browser doesn't
4644 request them anymore, and hence they don't need to be blocked here.
4645 But this naturally doesn't catch all banners, and some people choose
4646 not to use filters, so we need a comprehensive list of patterns for
4647 banner URLs here, and apply the <tt class="LITERAL"><a href=
4648 "actions-file.html#BLOCK">block</a></tt> action to them.</p>
4650 <p>First comes many generic patterns, which do most of the work, by
4651 matching typical domain and path name components of banners. Then
4652 comes a list of individual patterns for specific sites, which is
4653 omitted here to keep the example short:</p>
4655 <table class="c4" border="0" width="100%">
4658 <pre class="SCREEN">
4659 ##########################################################################
4660 # Block these fine banners:
4661 ##########################################################################
4662 { <a href="actions-file.html#BLOCK">+block{Banner ads.}</a> }
4670 /.*count(er)?\.(pl|cgi|exe|dll|asp|php[34]?)
4671 /(?:.*/)?(publicite|werbung|rekla(ma|me|am)|annonse|maino(kset|nta|s)?)/
4673 # Site-specific patterns (abbreviated):
4681 <p>It's quite remarkable how many advertisers actually call their
4682 banner servers ads.<tt class="REPLACEABLE c5">company</tt>.com, or
4683 call the directory in which the banners are stored simply
4684 <span class="QUOTE">"banners"</span>. So the above generic patterns
4685 are surprisingly effective.</p>
4687 <p>But being very generic, they necessarily also catch URLs that we
4688 don't want to block. The pattern <tt class="LITERAL">.*ads.</tt> e.g.
4689 catches <span class="QUOTE">"nasty-<span class=
4690 "emphasis EMPHASIS c2">ads</span>.nasty-corp.com"</span> as intended,
4691 but also <span class="QUOTE">"downlo<span class=
4692 "emphasis EMPHASIS c2">ads</span>.sourcefroge.net"</span> or
4693 <span class="QUOTE">"<span class=
4694 "emphasis EMPHASIS c2">ads</span>l.some-provider.net."</span> So here
4695 come some well-known exceptions to the <tt class="LITERAL">+<a href=
4696 "actions-file.html#BLOCK">block</a></tt> section above.</p>
4698 <p>Note that these are exceptions to exceptions from the default!
4699 Consider the URL <span class=
4700 "QUOTE">"downloads.sourcefroge.net"</span>: Initially, all actions
4701 are deactivated, so it wouldn't get blocked. Then comes the defaults
4702 section, which matches the URL, but just deactivates the <tt class=
4703 "LITERAL"><a href="actions-file.html#BLOCK">block</a></tt> action
4704 once again. Then it matches <tt class="LITERAL">.*ads.</tt>, an
4705 exception to the general non-blocking policy, and suddenly <tt class=
4706 "LITERAL"><a href="actions-file.html#BLOCK">+block</a></tt> applies.
4707 And now, it'll match <tt class="LITERAL">.*loads.</tt>, where
4708 <tt class="LITERAL"><a href="actions-file.html#BLOCK">-block</a></tt>
4709 applies, so (unless it matches <span class=
4710 "emphasis EMPHASIS c2">again</span> further down) it ends up with no
4711 <tt class="LITERAL"><a href="actions-file.html#BLOCK">block</a></tt>
4712 action applying.</p>
4714 <table class="c4" border="0" width="100%">
4717 <pre class="SCREEN">
4718 ##########################################################################
4719 # Save some innocent victims of the above generic block patterns:
4720 ##########################################################################
4724 { -<a href="actions-file.html#BLOCK">block</a> }
4725 adv[io]*. # (for advogato.org and advice.*)
4726 adsl. # (has nothing to do with ads)
4727 adobe. # (has nothing to do with ads either)
4728 ad[ud]*. # (adult.* and add.*)
4729 .edu # (universities don't host banners (yet!))
4730 .*loads. # (downloads, uploads etc)
4738 www.globalintersec.com/adv # (adv = advanced)
4739 www.ugu.com/sui/ugu/adv
4745 <p>Filtering source code can have nasty side effects, so make an
4746 exception for our friends at sourceforge.net, and all paths with
4747 <span class="QUOTE">"cvs"</span> in them. Note that <tt class=
4748 "LITERAL">-<a href="actions-file.html#FILTER">filter</a></tt>
4749 disables <span class="emphasis EMPHASIS c2">all</span> filters in one
4752 <table class="c4" border="0" width="100%">
4755 <pre class="SCREEN">
4756 # Don't filter code!
4758 { -<a href="actions-file.html#FILTER">filter</a> }
4769 <p>The actual <tt class="FILENAME">default.action</tt> is of course
4770 much more comprehensive, but we hope this example made clear how it
4775 <h3 class="SECT3"><a name="AEN4924" id="AEN4924">8.7.3.
4776 user.action</a></h3>
4778 <p>So far we are painting with a broad brush by setting general
4779 policies, which would be a reasonable starting point for many people.
4780 Now, you might want to be more specific and have customized rules
4781 that are more suitable to your personal habits and preferences. These
4782 would be for narrowly defined situations like your ISP or your bank,
4783 and should be placed in <tt class="FILENAME">user.action</tt>, which
4784 is parsed after all other actions files and hence has the last word,
4785 over-riding any previously defined actions. <tt class=
4786 "FILENAME">user.action</tt> is also a <span class=
4787 "emphasis EMPHASIS c2">safe</span> place for your personal settings,
4788 since <tt class="FILENAME">default.action</tt> is actively maintained
4789 by the <span class="APPLICATION">Privoxy</span> developers and you'll
4790 probably want to install updated versions from time to time.</p>
4792 <p>So let's look at a few examples of things that one might typically
4793 do in <tt class="FILENAME">user.action</tt>:</p>
4795 <table class="c4" border="0" width="100%">
4798 <pre class="SCREEN">
4799 # My user.action file. <fred@example.com>
4805 <p>As <a href="actions-file.html#ALIASES">aliases</a> are local to
4806 the actions file that they are defined in, you can't use the ones
4807 from <tt class="FILENAME">default.action</tt>, unless you repeat them
4810 <table class="c4" border="0" width="100%">
4813 <pre class="SCREEN">
4814 # Aliases are local to the file they are defined in.
4815 # (Re-)define aliases for this file:
4819 # These aliases just save typing later, and the alias names should
4820 # be self explanatory.
4822 +crunch-all-cookies = +crunch-incoming-cookies +crunch-outgoing-cookies
4823 -crunch-all-cookies = -crunch-incoming-cookies -crunch-outgoing-cookies
4824 allow-all-cookies = -crunch-all-cookies -session-cookies-only
4825 allow-popups = -filter{all-popups}
4826 +block-as-image = +block{Blocked as image.} +handle-as-image
4827 -block-as-image = -block
4829 # These aliases define combinations of actions that are useful for
4830 # certain types of sites:
4832 fragile = -block -crunch-all-cookies -filter -fast-redirects -hide-referrer
4833 shop = -crunch-all-cookies allow-popups
4835 # Allow ads for selected useful free sites:
4837 allow-ads = -block -filter{banners-by-size} -filter{banners-by-link}
4839 # Alias for specific file types that are text, but might have conflicting
4840 # MIME types. We want the browser to force these to be text documents.
4841 handle-as-text = -<a href="actions-file.html#FILTER">filter</a> +-<a href=
4842 "actions-file.html#CONTENT-TYPE-OVERWRITE">content-type-overwrite{text/plain}</a> +-<a href="actions-file.html#FORCE-TEXT-MODE">force-text-mode</a> -<a href="actions-file.html#HIDE-CONTENT-DISPOSITION">hide-content-disposition</a>
4848 <p>Say you have accounts on some sites that you visit regularly, and
4849 you don't want to have to log in manually each time. So you'd like to
4850 allow persistent cookies for these sites. The <tt class=
4851 "LITERAL">allow-all-cookies</tt> alias defined above does exactly
4852 that, i.e. it disables crunching of cookies in any direction, and the
4853 processing of cookies to make them only temporary.</p>
4855 <table class="c4" border="0" width="100%">
4858 <pre class="SCREEN">
4859 { allow-all-cookies }
4869 <p>Your bank is allergic to some filter, but you don't know which, so
4870 you disable them all:</p>
4872 <table class="c4" border="0" width="100%">
4875 <pre class="SCREEN">
4876 { -<a href="actions-file.html#FILTER">filter</a> }
4877 .your-home-banking-site.com
4883 <p>Some file types you may not want to filter for various
4886 <table class="c4" border="0" width="100%">
4889 <pre class="SCREEN">
4890 # Technical documentation is likely to contain strings that might
4891 # erroneously get altered by the JavaScript-oriented filters:
4896 # And this stupid host sends streaming video with a wrong MIME type,
4897 # so that Privoxy thinks it is getting HTML and starts filtering:
4899 stupid-server.example.com/
4905 <p>Example of a simple <a href="actions-file.html#BLOCK">block</a>
4906 action. Say you've seen an ad on your favourite page on example.com
4907 that you want to get rid of. You have right-clicked the image,
4908 selected <span class="QUOTE">"copy image location"</span> and pasted
4909 the URL below while removing the leading http://, into a <tt class=
4910 "LITERAL">{ +block{} }</tt> section. Note that <tt class="LITERAL">{
4911 +handle-as-image }</tt> need not be specified, since all URLs ending
4912 in <tt class="LITERAL">.gif</tt> will be tagged as images by the
4913 general rules as set in default.action anyway:</p>
4915 <table class="c4" border="0" width="100%">
4918 <pre class="SCREEN">
4919 { +<a href="actions-file.html#BLOCK">block</a>{Nasty ads.} }
4920 www.example.com/nasty-ads/sponsor\.gif
4921 another.example.net/more/junk/here/
4927 <p>The URLs of dynamically generated banners, especially from large
4928 banner farms, often don't use the well-known image file name
4929 extensions, which makes it impossible for <span class=
4930 "APPLICATION">Privoxy</span> to guess the file type just by looking
4931 at the URL. You can use the <tt class="LITERAL">+block-as-image</tt>
4932 alias defined above for these cases. Note that objects which match
4933 this rule but then turn out NOT to be an image are typically rendered
4934 as a <span class="QUOTE">"broken image"</span> icon by the browser.
4937 <table class="c4" border="0" width="100%">
4940 <pre class="SCREEN">
4951 <p>Now you noticed that the default configuration breaks Forbes
4952 Magazine, but you were too lazy to find out which action is the
4953 culprit, and you were again too lazy to give <a href=
4954 "contact.html">feedback</a>, so you just used the <tt class=
4955 "LITERAL">fragile</tt> alias on the site, and -- <span class=
4956 "emphasis EMPHASIS c2">whoa!</span> -- it worked. The <tt class=
4957 "LITERAL">fragile</tt> aliases disables those actions that are most
4958 likely to break a site. Also, good for testing purposes to see if it
4959 is <span class="APPLICATION">Privoxy</span> that is causing the
4960 problem or not. We later find other regular sites that misbehave, and
4961 add those to our personalized list of troublemakers:</p>
4963 <table class="c4" border="0" width="100%">
4966 <pre class="SCREEN">
4976 <p>You like the <span class="QUOTE">"fun"</span> text replacements in
4977 <tt class="FILENAME">default.filter</tt>, but it is disabled in the
4978 distributed actions file. So you'd like to turn it on in your
4979 private, update-safe config, once and for all:</p>
4981 <table class="c4" border="0" width="100%">
4984 <pre class="SCREEN">
4985 { +<a href="actions-file.html#FILTER-FUN">filter{fun}</a> }
4992 <p>Note that the above is not really a good idea: There are
4993 exceptions to the filters in <tt class="FILENAME">default.action</tt>
4994 for things that really shouldn't be filtered, like code on
4995 CVS->Web interfaces. Since <tt class="FILENAME">user.action</tt>
4996 has the last word, these exceptions won't be valid for the
4997 <span class="QUOTE">"fun"</span> filtering specified here.</p>
4999 <p>You might also worry about how your favourite free websites are
5000 funded, and find that they rely on displaying banner advertisements
5001 to survive. So you might want to specifically allow banners for those
5002 sites that you feel provide value to you:</p>
5004 <table class="c4" border="0" width="100%">
5007 <pre class="SCREEN">
5017 <p>Note that <tt class="LITERAL">allow-ads</tt> has been aliased to
5018 <tt class="LITERAL">-<a href=
5019 "actions-file.html#BLOCK">block</a></tt>, <tt class=
5021 "actions-file.html#FILTER-BANNERS-BY-SIZE">filter{banners-by-size}</a></tt>,
5022 and <tt class="LITERAL">-<a href=
5023 "actions-file.html#FILTER-BANNERS-BY-LINK">filter{banners-by-link}</a></tt>
5026 <p>Invoke another alias here to force an over-ride of the MIME type
5027 <tt class="LITERAL">application/x-sh</tt> which typically would open
5028 a download type dialog. In my case, I want to look at the shell
5029 script, and then I can save it should I choose to.</p>
5031 <table class="c4" border="0" width="100%">
5034 <pre class="SCREEN">
5042 <p><tt class="FILENAME">user.action</tt> is generally the best place
5043 to define exceptions and additions to the default policies of
5044 <tt class="FILENAME">default.action</tt>. Some actions are safe to
5045 have their default policies set here though. So let's set a default
5046 policy to have a <span class="QUOTE">"blank"</span> image as opposed
5047 to the checkerboard pattern for <span class=
5048 "emphasis EMPHASIS c2">ALL</span> sites. <span class=
5049 "QUOTE">"/"</span> of course matches all URL paths and patterns:</p>
5051 <table class="c4" border="0" width="100%">
5054 <pre class="SCREEN">
5056 "actions-file.html#SET-IMAGE-BLOCKER">set-image-blocker{blank}</a> }
5066 <div class="NAVFOOTER">
5067 <hr class="c1" width="100%">
5069 <table summary="Footer navigation table" width="100%" border="0"
5070 cellpadding="0" cellspacing="0">
5072 <td width="33%" align="left" valign="top"><a href="config.html"
5073 accesskey="P">Prev</a></td>
5075 <td width="34%" align="center" valign="top"><a href="index.html"
5076 accesskey="H">Home</a></td>
5078 <td width="33%" align="right" valign="top"><a href="filter-file.html"
5079 accesskey="N">Next</a></td>
5083 <td width="33%" align="left" valign="top">The Main Configuration
5086 <td width="34%" align="center" valign="top"> </td>
5088 <td width="33%" align="right" valign="top">Filter Files</td>