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58 <h1 class="SECT1"><a name="ACTIONS-FILE" id="ACTIONS-FILE">8. Actions
61 <p>The actions files are used to define what <span class=
62 "emphasis EMPHASIS c2">actions</span> <span class=
63 "APPLICATION">Privoxy</span> takes for which URLs, and thus determines
64 how ad images, cookies and various other aspects of HTTP content and
65 transactions are handled, and on which sites (or even parts thereof).
66 There are a number of such actions, with a wide range of functionality.
67 Each action does something a little different. These actions give us a
68 veritable arsenal of tools with which to exert our control, preferences
69 and independence. Actions can be combined so that their effects are
70 aggregated when applied against a given set of URLs.</p>
72 <p>There are three action files included with <span class=
73 "APPLICATION">Privoxy</span> with differing purposes:</p>
77 <p><tt class="FILENAME">match-all.action</tt> - is used to define
78 which <span class="QUOTE">"actions"</span> relating to
79 banner-blocking, images, pop-ups, content modification, cookie
80 handling etc should be applied by default. It should be the first
81 actions file loaded</p>
85 <p><tt class="FILENAME">default.action</tt> - defines many exceptions
86 (both positive and negative) from the default set of actions that's
87 configured in <tt class="FILENAME">match-all.action</tt>. It is a set
88 of rules that should work reasonably well as-is for most users. This
89 file is only supposed to be edited by the developers. It should be
90 the second actions file loaded.</p>
94 <p><tt class="FILENAME">user.action</tt> - is intended to be for
95 local site preferences and exceptions. As an example, if your ISP or
96 your bank has specific requirements, and need special handling, this
97 kind of thing should go here. This file will not be upgraded.</p>
101 <p><span class="GUIBUTTON">Edit</span> <span class="GUIBUTTON">Set to
102 Cautious</span> <span class="GUIBUTTON">Set to Medium</span>
103 <span class="GUIBUTTON">Set to Advanced</span></p>
105 <p>These have increasing levels of aggressiveness <span class=
106 "emphasis EMPHASIS c2">and have no influence on your browsing unless
107 you select them explicitly in the editor</span>. A default
108 installation should be pre-set to <tt class="LITERAL">Cautious</tt>.
109 New users should try this for a while before adjusting the settings
110 to more aggressive levels. The more aggressive the settings, then the
111 more likelihood there is of problems such as sites not working as
114 <p>The <span class="GUIBUTTON">Edit</span> button allows you to turn
115 each action on/off individually for fine-tuning. The <span class=
116 "GUIBUTTON">Cautious</span> button changes the actions list to
117 low/safe settings which will activate ad blocking and a minimal set
118 of <span class="APPLICATION">Privoxy</span>'s features, and
119 subsequently there will be less of a chance for accidental problems.
120 The <span class="GUIBUTTON">Medium</span> button sets the list to a
121 medium level of other features and a low level set of privacy
122 features. The <span class="GUIBUTTON">Advanced</span> button sets the
123 list to a high level of ad blocking and medium level of privacy. See
124 the chart below. The latter three buttons over-ride any changes via
125 with the <span class="GUIBUTTON">Edit</span> button. More fine-tuning
126 can be done in the lower sections of this internal page.</p>
128 <p>While the actions file editor allows to enable these settings in
129 all actions files, they are only supposed to be enabled in the first
130 one to make sure you don't unintentionally overrule earlier
133 <p>The default profiles, and their associated actions, as pre-defined
134 in <tt class="FILENAME">default.action</tt> are:</p>
137 <a name="AEN2780" id="AEN2780"></a>
139 <p class="c3">Table 1. Default Configurations</p>
141 <table border="1" frame="border" rules="all" class="CALSTABLE">
142 <col width="1*" title="C1">
143 <col width="1*" title="C2">
144 <col width="1*" title="C3">
145 <col width="1*" title="C4">
161 <td>Ad-blocking Aggressiveness</td>
171 <td>Ad-filtering by size</td>
181 <td>Ad-filtering by link</td>
191 <td>Pop-up killing</td>
201 <td>Privacy Features</td>
211 <td>Cookie handling</td>
215 <td>session-only</td>
221 <td>Referer forging</td>
231 <td>GIF de-animation</td>
241 <td>Fast redirects</td>
261 <td>JavaScript taming</td>
271 <td>Web-bug killing</td>
281 <td>Image tag reordering</td>
295 <p>The list of actions files to be used are defined in the main
296 configuration file, and are processed in the order they are defined (e.g.
297 <tt class="FILENAME">default.action</tt> is typically processed before
298 <tt class="FILENAME">user.action</tt>). The content of these can all be
299 viewed and edited from <a href="http://config.privoxy.org/show-status"
300 target="_top">http://config.privoxy.org/show-status</a>. The over-riding
301 principle when applying actions, is that the last action that matches a
302 given URL wins. The broadest, most general rules go first (defined in
303 <tt class="FILENAME">default.action</tt>), followed by any exceptions
304 (typically also in <tt class="FILENAME">default.action</tt>), which are
305 then followed lastly by any local preferences (typically in <span class=
306 "emphasis EMPHASIS c2">user</span><tt class="FILENAME">.action</tt>).
307 Generally, <tt class="FILENAME">user.action</tt> has the last word.</p>
309 <p>An actions file typically has multiple sections. If you want to use
310 <span class="QUOTE">"aliases"</span> in an actions file, you have to
311 place the (optional) <a href="actions-file.html#ALIASES">alias
312 section</a> at the top of that file. Then comes the default set of rules
313 which will apply universally to all sites and pages (be <span class=
314 "emphasis EMPHASIS c2">very careful</span> with using such a universal
315 set in <tt class="FILENAME">user.action</tt> or any other actions file
316 after <tt class="FILENAME">default.action</tt>, because it will override
317 the result from consulting any previous file). And then below that,
318 exceptions to the defined universal policies. You can regard <tt class=
319 "FILENAME">user.action</tt> as an appendix to <tt class=
320 "FILENAME">default.action</tt>, with the advantage that it is a separate
321 file, which makes preserving your personal settings across <span class=
322 "APPLICATION">Privoxy</span> upgrades easier.</p>
324 <p>Actions can be used to block anything you want, including ads,
325 banners, or just some obnoxious URL whose content you would rather not
326 see. Cookies can be accepted or rejected, or accepted only during the
327 current browser session (i.e. not written to disk), content can be
328 modified, some JavaScripts tamed, user-tracking fooled, and much more.
329 See below for a <a href="actions-file.html#ACTIONS">complete list of
333 <h2 class="SECT2"><a name="AEN2879" id="AEN2879">8.1. Finding the Right
336 <p>Note that some <a href="actions-file.html#ACTIONS">actions</a>, like
337 cookie suppression or script disabling, may render some sites unusable
338 that rely on these techniques to work properly. Finding the right mix
339 of actions is not always easy and certainly a matter of personal taste.
340 And, things can always change, requiring refinements in the
341 configuration. In general, it can be said that the more <span class=
342 "QUOTE">"aggressive"</span> your default settings (in the top section
343 of the actions file) are, the more exceptions for <span class=
344 "QUOTE">"trusted"</span> sites you will have to make later. If, for
345 example, you want to crunch all cookies per default, you'll have to
346 make exceptions from that rule for sites that you regularly use and
347 that require cookies for actually useful purposes, like maybe your
348 bank, favorite shop, or newspaper.</p>
350 <p>We have tried to provide you with reasonable rules to start from in
351 the distribution actions files. But there is no general rule of thumb
352 on these things. There just are too many variables, and sites are
353 constantly changing. Sooner or later you will want to change the rules
354 (and read this chapter again :).</p>
358 <h2 class="SECT2"><a name="AEN2886" id="AEN2886">8.2. How to
361 <p>The easiest way to edit the actions files is with a browser by using
362 our browser-based editor, which can be reached from <a href=
363 "http://config.privoxy.org/show-status" target=
364 "_top">http://config.privoxy.org/show-status</a>. Note: the config file
366 "config.html#ENABLE-EDIT-ACTIONS">enable-edit-actions</a> must be
367 enabled for this to work. The editor allows both fine-grained control
368 over every single feature on a per-URL basis, and easy choosing from
369 wholesale sets of defaults like <span class="QUOTE">"Cautious"</span>,
370 <span class="QUOTE">"Medium"</span> or <span class=
371 "QUOTE">"Advanced"</span>. Warning: the <span class=
372 "QUOTE">"Advanced"</span> setting is more aggressive, and will be more
373 likely to cause problems for some sites. Experienced users only!</p>
375 <p>If you prefer plain text editing to GUIs, you can of course also
376 directly edit the the actions files with your favorite text editor.
377 Look at <tt class="FILENAME">default.action</tt> which is richly
378 commented with many good examples.</p>
382 <h2 class="SECT2"><a name="ACTIONS-APPLY" id="ACTIONS-APPLY">8.3. How
383 Actions are Applied to Requests</a></h2>
385 <p>Actions files are divided into sections. There are special sections,
386 like the <span class="QUOTE">"<a href=
387 "actions-file.html#ALIASES">alias</a>"</span> sections which will be
388 discussed later. For now let's concentrate on regular sections: They
389 have a heading line (often split up to multiple lines for readability)
390 which consist of a list of actions, separated by whitespace and
391 enclosed in curly braces. Below that, there is a list of URL and tag
392 patterns, each on a separate line.</p>
394 <p>To determine which actions apply to a request, the URL of the
395 request is compared to all URL patterns in each <span class=
396 "QUOTE">"action file"</span>. Every time it matches, the list of
397 applicable actions for the request is incrementally updated, using the
398 heading of the section in which the pattern is located. The same is
399 done again for tags and tag patterns later on.</p>
401 <p>If multiple applying sections set the same action differently, the
402 last match wins. If not, the effects are aggregated. E.g. a URL might
403 match a regular section with a heading line of <tt class="LITERAL">{
404 +<a href="actions-file.html#HANDLE-AS-IMAGE">handle-as-image</a>
405 }</tt>, then later another one with just <tt class="LITERAL">{
406 +<a href="actions-file.html#BLOCK">block</a> }</tt>, resulting in
407 <span class="emphasis EMPHASIS c2">both</span> actions to apply. And
408 there may well be cases where you will want to combine actions
409 together. Such a section then might look like:</p>
411 <table class="c4" border="0" width="100%">
415 { +<tt class="LITERAL">handle-as-image</tt> +<tt class=
416 "LITERAL">block{Banner ads.}</tt> }
417 # Block these as if they were images. Send no block page.
419 media.example.com/.*banners
420 .example.com/images/ads/
426 <p>You can trace this process for URL patterns and any given URL by
427 visiting <a href="http://config.privoxy.org/show-url-info" target=
428 "_top">http://config.privoxy.org/show-url-info</a>.</p>
430 <p>Examples and more detail on this is provided in the Appendix,
431 <a href="appendix.html#ACTIONSANAT">Troubleshooting: Anatomy of an
432 Action</a> section.</p>
436 <h2 class="SECT2"><a name="AF-PATTERNS" id="AF-PATTERNS">8.4.
439 <p>As mentioned, <span class="APPLICATION">Privoxy</span> uses
440 <span class="QUOTE">"patterns"</span> to determine what <span class=
441 "emphasis EMPHASIS c2">actions</span> might apply to which sites and
442 pages your browser attempts to access. These <span class=
443 "QUOTE">"patterns"</span> use wild card type <span class=
444 "emphasis EMPHASIS c2">pattern</span> matching to achieve a high degree
445 of flexibility. This allows one expression to be expanded and
446 potentially match against many similar patterns.</p>
448 <p>Generally, an URL pattern has the form <tt class=
449 "LITERAL"><domain><port>/<path></tt>, where the
450 <tt class="LITERAL"><domain></tt>, the <tt class=
451 "LITERAL"><port></tt> and the <tt class=
452 "LITERAL"><path></tt> are optional. (This is why the special
453 <tt class="LITERAL">/</tt> pattern matches all URLs). Note that the
454 protocol portion of the URL pattern (e.g. <tt class=
455 "LITERAL">http://</tt>) should <span class=
456 "emphasis EMPHASIS c2">not</span> be included in the pattern. This is
459 <p>The pattern matching syntax is different for the domain and path
460 parts of the URL. The domain part uses a simple globbing type matching
461 technique, while the path part uses more flexible <a href=
462 "http://en.wikipedia.org/wiki/Regular_expressions" target=
463 "_top"><span class="QUOTE">"Regular Expressions"</span></a> (POSIX
466 <p>The port part of a pattern is a decimal port number preceded by a
467 colon (<tt class="LITERAL">:</tt>). If the domain part contains a
468 numerical IPv6 address, it has to be put into angle brackets
469 (<tt class="LITERAL"><</tt>, <tt class="LITERAL">></tt>).</p>
471 <div class="VARIABLELIST">
473 <dt><tt class="LITERAL">www.example.com/</tt></dt>
476 <p>is a domain-only pattern and will match any request to
477 <tt class="LITERAL">www.example.com</tt>, regardless of which
478 document on that server is requested. So ALL pages in this domain
479 would be covered by the scope of this action. Note that a simple
480 <tt class="LITERAL">example.com</tt> is different and would NOT
484 <dt><tt class="LITERAL">www.example.com</tt></dt>
487 <p>means exactly the same. For domain-only patterns, the trailing
488 <tt class="LITERAL">/</tt> may be omitted.</p>
491 <dt><tt class="LITERAL">www.example.com/index.html</tt></dt>
494 <p>matches all the documents on <tt class=
495 "LITERAL">www.example.com</tt> whose name starts with <tt class=
496 "LITERAL">/index.html</tt>.</p>
499 <dt><tt class="LITERAL">www.example.com/index.html$</tt></dt>
502 <p>matches only the single document <tt class=
503 "LITERAL">/index.html</tt> on <tt class=
504 "LITERAL">www.example.com</tt>.</p>
507 <dt><tt class="LITERAL">/index.html$</tt></dt>
510 <p>matches the document <tt class="LITERAL">/index.html</tt>,
511 regardless of the domain, i.e. on <span class=
512 "emphasis EMPHASIS c2">any</span> web server anywhere.</p>
515 <dt><tt class="LITERAL">/</tt></dt>
518 <p>Matches any URL because there's no requirement for either the
519 domain or the path to match anything.</p>
522 <dt><tt class="LITERAL">:8000/</tt></dt>
525 <p>Matches any URL pointing to TCP port 8000.</p>
528 <dt><tt class="LITERAL"><2001:db8::1>/</tt></dt>
531 <p>Matches any URL with the host address <tt class=
532 "LITERAL">2001:db8::1</tt>. (Note that the real URL uses plain
533 brackets, not angle brackets.)</p>
536 <dt><tt class="LITERAL">index.html</tt></dt>
539 <p>matches nothing, since it would be interpreted as a domain
540 name and there is no top-level domain called <tt class=
541 "LITERAL">.html</tt>. So its a mistake.</p>
547 <h3 class="SECT3"><a name="AEN2998" id="AEN2998">8.4.1. The Domain
550 <p>The matching of the domain part offers some flexible options: if
551 the domain starts or ends with a dot, it becomes unanchored at that
552 end. For example:</p>
554 <div class="VARIABLELIST">
556 <dt><tt class="LITERAL">.example.com</tt></dt>
559 <p>matches any domain with first-level domain <tt class=
560 "LITERAL">com</tt> and second-level domain <tt class=
561 "LITERAL">example</tt>. For example <tt class=
562 "LITERAL">www.example.com</tt>, <tt class=
563 "LITERAL">example.com</tt> and <tt class=
564 "LITERAL">foo.bar.baz.example.com</tt>. Note that it wouldn't
565 match if the second-level domain was <tt class=
566 "LITERAL">another-example</tt>.</p>
569 <dt><tt class="LITERAL">www.</tt></dt>
572 <p>matches any domain that <span class=
573 "emphasis EMPHASIS c2">STARTS</span> with <tt class=
574 "LITERAL">www.</tt> (It also matches the domain <tt class=
575 "LITERAL">www</tt> but most of the time that doesn't
579 <dt><tt class="LITERAL">.example.</tt></dt>
582 <p>matches any domain that <span class=
583 "emphasis EMPHASIS c2">CONTAINS</span> <tt class=
584 "LITERAL">.example.</tt>. And, by the way, also included would
585 be any files or documents that exist within that domain since
586 no path limitations are specified. (Correctly speaking: It
587 matches any FQDN that contains <tt class="LITERAL">example</tt>
588 as a domain.) This might be <tt class=
589 "LITERAL">www.example.com</tt>, <tt class=
590 "LITERAL">news.example.de</tt>, or <tt class=
591 "LITERAL">www.example.net/cgi/testing.pl</tt> for instance. All
592 these cases are matched.</p>
597 <p>Additionally, there are wild-cards that you can use in the domain
598 names themselves. These work similarly to shell globbing type
599 wild-cards: <span class="QUOTE">"*"</span> represents zero or more
600 arbitrary characters (this is equivalent to the <a href=
601 "http://en.wikipedia.org/wiki/Regular_expressions" target=
602 "_top"><span class="QUOTE">"Regular Expression"</span></a> based
603 syntax of <span class="QUOTE">".*"</span>), <span class=
604 "QUOTE">"?"</span> represents any single character (this is
605 equivalent to the regular expression syntax of a simple <span class=
606 "QUOTE">"."</span>), and you can define <span class=
607 "QUOTE">"character classes"</span> in square brackets which is
608 similar to the same regular expression technique. All of this can be
611 <div class="VARIABLELIST">
613 <dt><tt class="LITERAL">ad*.example.com</tt></dt>
616 <p>matches <span class="QUOTE">"adserver.example.com"</span>,
617 <span class="QUOTE">"ads.example.com"</span>, etc but not
618 <span class="QUOTE">"sfads.example.com"</span></p>
621 <dt><tt class="LITERAL">*ad*.example.com</tt></dt>
624 <p>matches all of the above, and then some.</p>
627 <dt><tt class="LITERAL">.?pix.com</tt></dt>
630 <p>matches <tt class="LITERAL">www.ipix.com</tt>, <tt class=
631 "LITERAL">pictures.epix.com</tt>, <tt class=
632 "LITERAL">a.b.c.d.e.upix.com</tt> etc.</p>
635 <dt><tt class="LITERAL">www[1-9a-ez].example.c*</tt></dt>
638 <p>matches <tt class="LITERAL">www1.example.com</tt>,
639 <tt class="LITERAL">www4.example.cc</tt>, <tt class=
640 "LITERAL">wwwd.example.cy</tt>, <tt class=
641 "LITERAL">wwwz.example.com</tt> etc., but <span class=
642 "emphasis EMPHASIS c2">not</span> <tt class=
643 "LITERAL">wwww.example.com</tt>.</p>
648 <p>While flexible, this is not the sophistication of full regular
649 expression based syntax.</p>
653 <h3 class="SECT3"><a name="AEN3074" id="AEN3074">8.4.2. The Path
656 <p><span class="APPLICATION">Privoxy</span> uses <span class=
657 "QUOTE">"modern"</span> POSIX 1003.2 <a href=
658 "http://en.wikipedia.org/wiki/Regular_expressions" target=
659 "_top"><span class="QUOTE">"Regular Expressions"</span></a> for
660 matching the path portion (after the slash), and is thus more
663 <p>There is an <a href="appendix.html#REGEX">Appendix</a> with a
664 brief quick-start into regular expressions, you also might want to
665 have a look at your operating system's documentation on regular
666 expressions (try <tt class="LITERAL">man re_format</tt>).</p>
668 <p>Note that the path pattern is automatically left-anchored at the
669 <span class="QUOTE">"/"</span>, i.e. it matches as if it would start
670 with a <span class="QUOTE">"^"</span> (regular expression speak for
671 the beginning of a line).</p>
673 <p>Please also note that matching in the path is <span class=
674 "emphasis EMPHASIS c2">CASE INSENSITIVE</span> by default, but you
675 can switch to case sensitive at any point in the pattern by using the
676 <span class="QUOTE">"(?-i)"</span> switch: <tt class=
677 "LITERAL">www.example.com/(?-i)PaTtErN.*</tt> will match only
678 documents whose path starts with <tt class="LITERAL">PaTtErN</tt> in
679 <span class="emphasis EMPHASIS c2">exactly</span> this
682 <div class="VARIABLELIST">
684 <dt><tt class="LITERAL">.example.com/.*</tt></dt>
687 <p>Is equivalent to just <span class=
688 "QUOTE">".example.com"</span>, since any documents within that
689 domain are matched with or without the <span class=
690 "QUOTE">".*"</span> regular expression. This is redundant</p>
693 <dt><tt class="LITERAL">.example.com/.*/index.html$</tt></dt>
696 <p>Will match any page in the domain of <span class=
697 "QUOTE">"example.com"</span> that is named <span class=
698 "QUOTE">"index.html"</span>, and that is part of some path. For
699 example, it matches <span class=
700 "QUOTE">"www.example.com/testing/index.html"</span> but NOT
701 <span class="QUOTE">"www.example.com/index.html"</span> because
702 the regular expression called for at least two <span class=
703 "QUOTE">"/'s"</span>, thus the path requirement. It also would
705 "QUOTE">"www.example.com/testing/index_html"</span>, because of
706 the special meta-character <span class="QUOTE">"."</span>.</p>
709 <dt><tt class="LITERAL">.example.com/(.*/)?index\.html$</tt></dt>
712 <p>This regular expression is conditional so it will match any
713 page named <span class="QUOTE">"index.html"</span> regardless
714 of path which in this case can have one or more <span class=
715 "QUOTE">"/'s"</span>. And this one must contain exactly
716 <span class="QUOTE">".html"</span> (but does not have to end
721 "LITERAL">.example.com/(.*/)(ads|banners?|junk)</tt></dt>
724 <p>This regular expression will match any path of <span class=
725 "QUOTE">"example.com"</span> that contains any of the words
726 <span class="QUOTE">"ads"</span>, <span class=
727 "QUOTE">"banner"</span>, <span class="QUOTE">"banners"</span>
728 (because of the <span class="QUOTE">"?"</span>) or <span class=
729 "QUOTE">"junk"</span>. The path does not have to end in these
730 words, just contain them.</p>
734 "LITERAL">.example.com/(.*/)(ads|banners?|junk)/.*\.(jpe?g|gif|png)$</tt></dt>
737 <p>This is very much the same as above, except now it must end
738 in either <span class="QUOTE">".jpg"</span>, <span class=
739 "QUOTE">".jpeg"</span>, <span class="QUOTE">".gif"</span> or
740 <span class="QUOTE">".png"</span>. So this one is limited to
741 common image formats.</p>
746 <p>There are many, many good examples to be found in <tt class=
747 "FILENAME">default.action</tt>, and more tutorials below in <a href=
748 "appendix.html#REGEX">Appendix on regular expressions</a>.</p>
752 <h3 class="SECT3"><a name="TAG-PATTERN" id="TAG-PATTERN">8.4.3. The
755 <p>Tag patterns are used to change the applying actions based on the
756 request's tags. Tags can be created with either the <a href=
757 "actions-file.html#CLIENT-HEADER-TAGGER">client-header-tagger</a> or
759 "actions-file.html#SERVER-HEADER-TAGGER">server-header-tagger</a>
762 <p>Tag patterns have to start with <span class="QUOTE">"TAG:"</span>,
763 so <span class="APPLICATION">Privoxy</span> can tell them apart from
764 URL patterns. Everything after the colon including white space, is
765 interpreted as a regular expression with path pattern syntax, except
766 that tag patterns aren't left-anchored automatically (<span class=
767 "APPLICATION">Privoxy</span> doesn't silently add a <span class=
768 "QUOTE">"^"</span>, you have to do it yourself if you need it).</p>
770 <p>To match all requests that are tagged with <span class=
771 "QUOTE">"foo"</span> your pattern line should be <span class=
772 "QUOTE">"TAG:^foo$"</span>, <span class="QUOTE">"TAG:foo"</span>
773 would work as well, but it would also match requests whose tags
774 contain <span class="QUOTE">"foo"</span> somewhere. <span class=
775 "QUOTE">"TAG: foo"</span> wouldn't work as it requires white
778 <p>Sections can contain URL and tag patterns at the same time, but
779 tag patterns are checked after the URL patterns and thus always
780 overrule them, even if they are located before the URL patterns.</p>
782 <p>Once a new tag is added, Privoxy checks right away if it's matched
783 by one of the tag patterns and updates the action settings
784 accordingly. As a result tags can be used to activate other tagger
785 actions, as long as these other taggers look for headers that haven't
786 already be parsed.</p>
788 <p>For example you could tag client requests which use the <tt class=
789 "LITERAL">POST</tt> method, then use this tag to activate another
790 tagger that adds a tag if cookies are sent, and then use a block
791 action based on the cookie tag. This allows the outcome of one
792 action, to be input into a subsequent action. However if you'd
793 reverse the position of the described taggers, and activated the
794 method tagger based on the cookie tagger, no method tags would be
795 created. The method tagger would look for the request line, but at
796 the time the cookie tag is created, the request line has already been
799 <p>While this is a limitation you should be aware of, this kind of
800 indirection is seldom needed anyway and even the example doesn't make
806 <h2 class="SECT2"><a name="ACTIONS" id="ACTIONS">8.5. Actions</a></h2>
808 <p>All actions are disabled by default, until they are explicitly
809 enabled somewhere in an actions file. Actions are turned on if preceded
810 with a <span class="QUOTE">"+"</span>, and turned off if preceded with
811 a <span class="QUOTE">"-"</span>. So a <tt class="LITERAL">+action</tt>
812 means <span class="QUOTE">"do that action"</span>, e.g. <tt class=
813 "LITERAL">+block</tt> means <span class="QUOTE">"please block URLs that
814 match the following patterns"</span>, and <tt class=
815 "LITERAL">-block</tt> means <span class="QUOTE">"don't block URLs that
816 match the following patterns, even if <tt class="LITERAL">+block</tt>
817 previously applied."</span></p>
819 <p>Again, actions are invoked by placing them on a line, enclosed in
820 curly braces and separated by whitespace, like in <tt class=
821 "LITERAL">{+some-action -some-other-action{some-parameter}}</tt>,
822 followed by a list of URL patterns, one per line, to which they apply.
823 Together, the actions line and the following pattern lines make up a
824 section of the actions file.</p>
826 <p>Actions fall into three categories:</p>
830 <p>Boolean, i.e the action can only be <span class=
831 "QUOTE">"enabled"</span> or <span class="QUOTE">"disabled"</span>.
834 <table class="c4" border="0" width="90%">
838 +<tt class="REPLACEABLE c5">name</tt> # enable action <tt class=
839 "REPLACEABLE c5">name</tt>
840 -<tt class="REPLACEABLE c5">name</tt> # disable action <tt class=
841 "REPLACEABLE c5">name</tt>
847 <p>Example: <tt class="LITERAL">+handle-as-image</tt></p>
851 <p>Parameterized, where some value is required in order to enable
852 this type of action. Syntax:</p>
854 <table class="c4" border="0" width="90%">
858 +<tt class="REPLACEABLE c5">name</tt>{<tt class=
859 "REPLACEABLE c5">param</tt>} # enable action and set parameter to <tt class=
860 "REPLACEABLE c5">param</tt>,
861 # overwriting parameter from previous match if necessary
863 "REPLACEABLE c5">name</tt> # disable action. The parameter can be omitted
869 <p>Note that if the URL matches multiple positive forms of a
870 parameterized action, the last match wins, i.e. the params from
871 earlier matches are simply ignored.</p>
873 <p>Example: <tt class="LITERAL">+hide-user-agent{Mozilla/5.0 (X11;
874 U; FreeBSD i386; en-US; rv:1.8.1.4) Gecko/20070602
875 Firefox/2.0.0.4}</tt></p>
879 <p>Multi-value. These look exactly like parameterized actions, but
880 they behave differently: If the action applies multiple times to
881 the same URL, but with different parameters, <span class=
882 "emphasis EMPHASIS c2">all</span> the parameters from <span class=
883 "emphasis EMPHASIS c2">all</span> matches are remembered. This is
884 used for actions that can be executed for the same request
885 repeatedly, like adding multiple headers, or filtering through
886 multiple filters. Syntax:</p>
888 <table class="c4" border="0" width="90%">
892 +<tt class="REPLACEABLE c5">name</tt>{<tt class=
893 "REPLACEABLE c5">param</tt>} # enable action and add <tt class=
894 "REPLACEABLE c5">param</tt> to the list of parameters
895 -<tt class="REPLACEABLE c5">name</tt>{<tt class=
896 "REPLACEABLE c5">param</tt>} # remove the parameter <tt class=
897 "REPLACEABLE c5">param</tt> from the list of parameters
898 # If it was the last one left, disable the action.
900 "REPLACEABLE c5">-name</tt> # disable this action completely and remove all parameters from the list
906 <p>Examples: <tt class="LITERAL">+add-header{X-Fun-Header: Some
907 text}</tt> and <tt class=
908 "LITERAL">+filter{html-annoyances}</tt></p>
912 <p>If nothing is specified in any actions file, no <span class=
913 "QUOTE">"actions"</span> are taken. So in this case <span class=
914 "APPLICATION">Privoxy</span> would just be a normal, non-blocking,
915 non-filtering proxy. You must specifically enable the privacy and
916 blocking features you need (although the provided default actions files
917 will give a good starting point).</p>
919 <p>Later defined action sections always over-ride earlier ones of the
920 same type. So exceptions to any rules you make, should come in the
921 latter part of the file (or in a file that is processed later when
922 using multiple actions files such as <tt class=
923 "FILENAME">user.action</tt>). For multi-valued actions, the actions are
924 applied in the order they are specified. Actions files are processed in
925 the order they are defined in <tt class="FILENAME">config</tt> (the
926 default installation has three actions files). It also quite possible
927 for any given URL to match more than one <span class=
928 "QUOTE">"pattern"</span> (because of wildcards and regular
929 expressions), and thus to trigger more than one set of actions! Last
932 <p>The list of valid <span class="APPLICATION">Privoxy</span> actions
936 <h4 class="SECT3"><a name="ADD-HEADER" id="ADD-HEADER">8.5.1.
939 <div class="VARIABLELIST">
941 <dt>Typical use:</dt>
944 <p>Confuse log analysis, custom applications</p>
950 <p>Sends a user defined HTTP header to the web server.</p>
962 <p>Any string value is possible. Validity of the defined HTTP
963 headers is not checked. It is recommended that you use the
964 <span class="QUOTE">"<tt class="LITERAL">X-</tt>"</span> prefix
965 for custom headers.</p>
971 <p>This action may be specified multiple times, in order to
972 define multiple headers. This is rarely needed for the typical
973 user. If you don't know what <span class="QUOTE">"HTTP
974 headers"</span> are, you definitely don't need to worry about
977 <p>Headers added by this action are not modified by other
981 <dt>Example usage:</dt>
984 <table class="c4" border="0" width="90%">
988 +add-header{X-User-Tracking: sucks}
999 <h4 class="SECT3"><a name="BLOCK" id="BLOCK">8.5.2. block</a></h4>
1001 <div class="VARIABLELIST">
1003 <dt>Typical use:</dt>
1006 <p>Block ads or other unwanted content</p>
1012 <p>Requests for URLs to which this action applies are blocked,
1013 i.e. the requests are trapped by <span class=
1014 "APPLICATION">Privoxy</span> and the requested URL is never
1015 retrieved, but is answered locally with a substitute page or
1016 image, as determined by the <tt class="LITERAL"><a href=
1017 "actions-file.html#HANDLE-AS-IMAGE">handle-as-image</a></tt>,
1018 <tt class="LITERAL"><a href=
1019 "actions-file.html#SET-IMAGE-BLOCKER">set-image-blocker</a></tt>,
1020 and <tt class="LITERAL"><a href=
1021 "actions-file.html#HANDLE-AS-EMPTY-DOCUMENT">handle-as-empty-document</a></tt>
1028 <p>Parameterized.</p>
1034 <p>A block reason that should be given to the user.</p>
1040 <p><span class="APPLICATION">Privoxy</span> sends a special
1041 <span class="QUOTE">"BLOCKED"</span> page for requests to
1042 blocked pages. This page contains the block reason given as
1043 parameter, a link to find out why the block action applies, and
1044 a click-through to the blocked content (the latter only if the
1045 force feature is available and enabled).</p>
1047 <p>A very important exception occurs if <span class=
1048 "emphasis EMPHASIS c2">both</span> <tt class=
1049 "LITERAL">block</tt> and <tt class="LITERAL"><a href=
1050 "actions-file.html#HANDLE-AS-IMAGE">handle-as-image</a></tt>,
1051 apply to the same request: it will then be replaced by an
1052 image. If <tt class="LITERAL"><a href=
1053 "actions-file.html#SET-IMAGE-BLOCKER">set-image-blocker</a></tt>
1054 (see below) also applies, the type of image will be determined
1055 by its parameter, if not, the standard checkerboard pattern is
1058 <p>It is important to understand this process, in order to
1059 understand how <span class="APPLICATION">Privoxy</span> deals
1060 with ads and other unwanted content. Blocking is a core
1061 feature, and one upon which various other features depend.</p>
1063 <p>The <tt class="LITERAL"><a href=
1064 "actions-file.html#FILTER">filter</a></tt> action can perform a
1065 very similar task, by <span class="QUOTE">"blocking"</span>
1066 banner images and other content through rewriting the relevant
1067 URLs in the document's HTML source, so they don't get requested
1068 in the first place. Note that this is a totally different
1069 technique, and it's easy to confuse the two.</p>
1072 <dt>Example usage (section):</dt>
1075 <table class="c4" border="0" width="90%">
1078 <pre class="SCREEN">
1079 {+block{No nasty stuff for you.}}
1080 # Block and replace with "blocked" page
1081 .nasty-stuff.example.com
1083 {+block{Doubleclick banners.} +handle-as-image}
1084 # Block and replace with image
1088 {+block{Layered ads.} +handle-as-empty-document}
1089 # Block and then ignore
1090 adserver.example.net/.*\.js$
1101 <h4 class="SECT3"><a name="CHANGE-X-FORWARDED-FOR" id=
1102 "CHANGE-X-FORWARDED-FOR">8.5.3. change-x-forwarded-for</a></h4>
1104 <div class="VARIABLELIST">
1106 <dt>Typical use:</dt>
1109 <p>Improve privacy by not forwarding the source of the request
1110 in the HTTP headers.</p>
1116 <p>Deletes the <span class="QUOTE">"X-Forwarded-For:"</span>
1117 HTTP header from the client request, or adds a new one.</p>
1123 <p>Parameterized.</p>
1131 <p><span class="QUOTE">"block"</span> to delete the
1136 <p><span class="QUOTE">"add"</span> to create the header
1137 (or append the client's IP address to an already existing
1146 <p>It is safe and recommended to use <tt class=
1147 "LITERAL">block</tt>.</p>
1149 <p>Forwarding the source address of the request may make sense
1150 in some multi-user setups but is also a privacy risk.</p>
1153 <dt>Example usage:</dt>
1156 <table class="c4" border="0" width="90%">
1159 <pre class="SCREEN">
1160 +change-x-forwarded-for{block}
1171 <h4 class="SECT3"><a name="CLIENT-HEADER-FILTER" id=
1172 "CLIENT-HEADER-FILTER">8.5.4. client-header-filter</a></h4>
1174 <div class="VARIABLELIST">
1176 <dt>Typical use:</dt>
1179 <p>Rewrite or remove single client headers.</p>
1185 <p>All client headers to which this action applies are filtered
1186 on-the-fly through the specified regular expression based
1193 <p>Parameterized.</p>
1199 <p>The name of a client-header filter, as defined in one of the
1200 <a href="filter-file.html">filter files</a>.</p>
1206 <p>Client-header filters are applied to each header on its own,
1207 not to all at once. This makes it easier to diagnose problems,
1208 but on the downside you can't write filters that only change
1209 header x if header y's value is z. You can do that by using
1212 <p>Client-header filters are executed after the other header
1213 actions have finished and use their output as input.</p>
1215 <p>If the request URL gets changed, <span class=
1216 "APPLICATION">Privoxy</span> will detect that and use the new
1217 one. This can be used to rewrite the request destination behind
1218 the client's back, for example to specify a Tor exit relay for
1219 certain requests.</p>
1221 <p>Please refer to the <a href="filter-file.html">filter file
1222 chapter</a> to learn which client-header filters are available
1223 by default, and how to create your own.</p>
1226 <dt>Example usage (section):</dt>
1229 <table class="c4" border="0" width="90%">
1232 <pre class="SCREEN">
1233 # Hide Tor exit notation in Host and Referer Headers
1234 {+client-header-filter{hide-tor-exit-notation}}
1247 <h4 class="SECT3"><a name="CLIENT-HEADER-TAGGER" id=
1248 "CLIENT-HEADER-TAGGER">8.5.5. client-header-tagger</a></h4>
1250 <div class="VARIABLELIST">
1252 <dt>Typical use:</dt>
1255 <p>Block requests based on their headers.</p>
1261 <p>Client headers to which this action applies are filtered
1262 on-the-fly through the specified regular expression based
1263 substitutions, the result is used as tag.</p>
1269 <p>Parameterized.</p>
1275 <p>The name of a client-header tagger, as defined in one of the
1276 <a href="filter-file.html">filter files</a>.</p>
1282 <p>Client-header taggers are applied to each header on its own,
1283 and as the header isn't modified, each tagger <span class=
1284 "QUOTE">"sees"</span> the original.</p>
1286 <p>Client-header taggers are the first actions that are
1287 executed and their tags can be used to control every other
1291 <dt>Example usage (section):</dt>
1294 <table class="c4" border="0" width="90%">
1297 <pre class="SCREEN">
1298 # Tag every request with the User-Agent header
1299 {+client-header-tagger{user-agent}}
1302 # Tagging itself doesn't change the action
1303 # settings, sections with TAG patterns do:
1305 # If it's a download agent, use a different forwarding proxy,
1306 # show the real User-Agent and make sure resume works.
1307 {+forward-override{forward-socks5 10.0.0.2:2222 .} \
1308 -hide-if-modified-since \
1309 -overwrite-last-modified \
1314 TAG:^User-Agent: NetBSD-ftp/
1315 TAG:^User-Agent: Novell ZYPP Installer
1316 TAG:^User-Agent: RPM APT-HTTP/
1317 TAG:^User-Agent: fetch libfetch/
1318 TAG:^User-Agent: Ubuntu APT-HTTP/
1319 TAG:^User-Agent: MPlayer/
1331 <h4 class="SECT3"><a name="CONTENT-TYPE-OVERWRITE" id=
1332 "CONTENT-TYPE-OVERWRITE">8.5.6. content-type-overwrite</a></h4>
1334 <div class="VARIABLELIST">
1336 <dt>Typical use:</dt>
1339 <p>Stop useless download menus from popping up, or change the
1340 browser's rendering mode</p>
1346 <p>Replaces the <span class="QUOTE">"Content-Type:"</span> HTTP
1353 <p>Parameterized.</p>
1365 <p>The <span class="QUOTE">"Content-Type:"</span> HTTP server
1366 header is used by the browser to decide what to do with the
1367 document. The value of this header can cause the browser to
1368 open a download menu instead of displaying the document by
1369 itself, even if the document's format is supported by the
1372 <p>The declared content type can also affect which rendering
1373 mode the browser chooses. If XHTML is delivered as <span class=
1374 "QUOTE">"text/html"</span>, many browsers treat it as yet
1375 another broken HTML document. If it is send as <span class=
1376 "QUOTE">"application/xml"</span>, browsers with XHTML support
1377 will only display it, if the syntax is correct.</p>
1379 <p>If you see a web site that proudly uses XHTML buttons, but
1380 sets <span class="QUOTE">"Content-Type: text/html"</span>, you
1381 can use <span class="APPLICATION">Privoxy</span> to overwrite
1382 it with <span class="QUOTE">"application/xml"</span> and
1383 validate the web master's claim inside your XHTML-supporting
1384 browser. If the syntax is incorrect, the browser will complain
1387 <p>You can also go the opposite direction: if your browser
1388 prints error messages instead of rendering a document falsely
1389 declared as XHTML, you can overwrite the content type with
1390 <span class="QUOTE">"text/html"</span> and have it rendered as
1391 broken HTML document.</p>
1393 <p>By default <tt class="LITERAL">content-type-overwrite</tt>
1394 only replaces <span class="QUOTE">"Content-Type:"</span>
1395 headers that look like some kind of text. If you want to
1396 overwrite it unconditionally, you have to combine it with
1397 <tt class="LITERAL"><a href=
1398 "actions-file.html#FORCE-TEXT-MODE">force-text-mode</a></tt>.
1399 This limitation exists for a reason, think twice before
1400 circumventing it.</p>
1402 <p>Most of the time it's easier to replace this action with a
1403 custom <tt class="LITERAL"><a href=
1404 "actions-file.html#SERVER-HEADER-FILTER">server-header
1405 filter</a></tt>. It allows you to activate it for every
1406 document of a certain site and it will still only replace the
1407 content types you aimed at.</p>
1409 <p>Of course you can apply <tt class=
1410 "LITERAL">content-type-overwrite</tt> to a whole site and then
1411 make URL based exceptions, but it's a lot more work to get the
1415 <dt>Example usage (sections):</dt>
1418 <table class="c4" border="0" width="90%">
1421 <pre class="SCREEN">
1422 # Check if www.example.net/ really uses valid XHTML
1423 { +content-type-overwrite{application/xml} }
1426 # but leave the content type unmodified if the URL looks like a style sheet
1427 {-content-type-overwrite}
1428 www.example.net/.*\.css$
1429 www.example.net/.*style
1440 <h4 class="SECT3"><a name="CRUNCH-CLIENT-HEADER" id=
1441 "CRUNCH-CLIENT-HEADER">8.5.7. crunch-client-header</a></h4>
1443 <div class="VARIABLELIST">
1445 <dt>Typical use:</dt>
1448 <p>Remove a client header <span class=
1449 "APPLICATION">Privoxy</span> has no dedicated action for.</p>
1455 <p>Deletes every header sent by the client that contains the
1456 string the user supplied as parameter.</p>
1462 <p>Parameterized.</p>
1474 <p>This action allows you to block client headers for which no
1475 dedicated <span class="APPLICATION">Privoxy</span> action
1476 exists. <span class="APPLICATION">Privoxy</span> will remove
1477 every client header that contains the string you supplied as
1480 <p>Regular expressions are <span class=
1481 "emphasis EMPHASIS c2">not supported</span> and you can't use
1482 this action to block different headers in the same request,
1483 unless they contain the same string.</p>
1485 <p><tt class="LITERAL">crunch-client-header</tt> is only meant
1486 for quick tests. If you have to block several different
1487 headers, or only want to modify parts of them, you should use a
1488 <tt class="LITERAL"><a href=
1489 "actions-file.html#CLIENT-HEADER-FILTER">client-header
1490 filter</a></tt>.</p>
1492 <div class="WARNING">
1493 <table class="WARNING" border="1" width="90%">
1495 <td class="c6" align="center">Warning</td>
1500 <p>Don't block any header without understanding the
1508 <dt>Example usage (section):</dt>
1511 <table class="c4" border="0" width="90%">
1514 <pre class="SCREEN">
1515 # Block the non-existent "Privacy-Violation:" client header
1516 { +crunch-client-header{Privacy-Violation:} }
1529 <h4 class="SECT3"><a name="CRUNCH-IF-NONE-MATCH" id=
1530 "CRUNCH-IF-NONE-MATCH">8.5.8. crunch-if-none-match</a></h4>
1532 <div class="VARIABLELIST">
1534 <dt>Typical use:</dt>
1537 <p>Prevent yet another way to track the user's steps between
1544 <p>Deletes the <span class="QUOTE">"If-None-Match:"</span> HTTP
1563 <p>Removing the <span class="QUOTE">"If-None-Match:"</span>
1564 HTTP client header is useful for filter testing, where you want
1565 to force a real reload instead of getting status code
1566 <span class="QUOTE">"304"</span> which would cause the browser
1567 to use a cached copy of the page.</p>
1569 <p>It is also useful to make sure the header isn't used as a
1570 cookie replacement (unlikely but possible).</p>
1572 <p>Blocking the <span class="QUOTE">"If-None-Match:"</span>
1573 header shouldn't cause any caching problems, as long as the
1574 <span class="QUOTE">"If-Modified-Since:"</span> header isn't
1575 blocked or missing as well.</p>
1577 <p>It is recommended to use this action together with
1578 <tt class="LITERAL"><a href=
1579 "actions-file.html#HIDE-IF-MODIFIED-SINCE">hide-if-modified-since</a></tt>
1580 and <tt class="LITERAL"><a href=
1581 "actions-file.html#OVERWRITE-LAST-MODIFIED">overwrite-last-modified</a></tt>.</p>
1584 <dt>Example usage (section):</dt>
1587 <table class="c4" border="0" width="90%">
1590 <pre class="SCREEN">
1591 # Let the browser revalidate cached documents but don't
1592 # allow the server to use the revalidation headers for user tracking.
1593 {+hide-if-modified-since{-60} \
1594 +overwrite-last-modified{randomize} \
1595 +crunch-if-none-match}
1607 <h4 class="SECT3"><a name="CRUNCH-INCOMING-COOKIES" id=
1608 "CRUNCH-INCOMING-COOKIES">8.5.9. crunch-incoming-cookies</a></h4>
1610 <div class="VARIABLELIST">
1612 <dt>Typical use:</dt>
1615 <p>Prevent the web server from setting HTTP cookies on your
1622 <p>Deletes any <span class="QUOTE">"Set-Cookie:"</span> HTTP
1623 headers from server replies.</p>
1641 <p>This action is only concerned with <span class=
1642 "emphasis EMPHASIS c2">incoming</span> HTTP cookies. For
1643 <span class="emphasis EMPHASIS c2">outgoing</span> HTTP
1644 cookies, use <tt class="LITERAL"><a href=
1645 "actions-file.html#CRUNCH-OUTGOING-COOKIES">crunch-outgoing-cookies</a></tt>.
1646 Use <span class="emphasis EMPHASIS c2">both</span> to disable
1647 HTTP cookies completely.</p>
1649 <p>It makes <span class="emphasis EMPHASIS c2">no sense at
1650 all</span> to use this action in conjunction with the
1651 <tt class="LITERAL"><a href=
1652 "actions-file.html#SESSION-COOKIES-ONLY">session-cookies-only</a></tt>
1653 action, since it would prevent the session cookies from being
1654 set. See also <tt class="LITERAL"><a href=
1655 "actions-file.html#FILTER-CONTENT-COOKIES">filter-content-cookies</a></tt>.</p>
1658 <dt>Example usage:</dt>
1661 <table class="c4" border="0" width="90%">
1664 <pre class="SCREEN">
1665 +crunch-incoming-cookies
1676 <h4 class="SECT3"><a name="CRUNCH-SERVER-HEADER" id=
1677 "CRUNCH-SERVER-HEADER">8.5.10. crunch-server-header</a></h4>
1679 <div class="VARIABLELIST">
1681 <dt>Typical use:</dt>
1684 <p>Remove a server header <span class=
1685 "APPLICATION">Privoxy</span> has no dedicated action for.</p>
1691 <p>Deletes every header sent by the server that contains the
1692 string the user supplied as parameter.</p>
1698 <p>Parameterized.</p>
1710 <p>This action allows you to block server headers for which no
1711 dedicated <span class="APPLICATION">Privoxy</span> action
1712 exists. <span class="APPLICATION">Privoxy</span> will remove
1713 every server header that contains the string you supplied as
1716 <p>Regular expressions are <span class=
1717 "emphasis EMPHASIS c2">not supported</span> and you can't use
1718 this action to block different headers in the same request,
1719 unless they contain the same string.</p>
1721 <p><tt class="LITERAL">crunch-server-header</tt> is only meant
1722 for quick tests. If you have to block several different
1723 headers, or only want to modify parts of them, you should use a
1724 custom <tt class="LITERAL"><a href=
1725 "actions-file.html#SERVER-HEADER-FILTER">server-header
1726 filter</a></tt>.</p>
1728 <div class="WARNING">
1729 <table class="WARNING" border="1" width="90%">
1731 <td class="c6" align="center">Warning</td>
1736 <p>Don't block any header without understanding the
1744 <dt>Example usage (section):</dt>
1747 <table class="c4" border="0" width="90%">
1750 <pre class="SCREEN">
1751 # Crunch server headers that try to prevent caching
1752 { +crunch-server-header{no-cache} }
1764 <h4 class="SECT3"><a name="CRUNCH-OUTGOING-COOKIES" id=
1765 "CRUNCH-OUTGOING-COOKIES">8.5.11. crunch-outgoing-cookies</a></h4>
1767 <div class="VARIABLELIST">
1769 <dt>Typical use:</dt>
1772 <p>Prevent the web server from reading any HTTP cookies from
1779 <p>Deletes any <span class="QUOTE">"Cookie:"</span> HTTP
1780 headers from client requests.</p>
1798 <p>This action is only concerned with <span class=
1799 "emphasis EMPHASIS c2">outgoing</span> HTTP cookies. For
1800 <span class="emphasis EMPHASIS c2">incoming</span> HTTP
1801 cookies, use <tt class="LITERAL"><a href=
1802 "actions-file.html#CRUNCH-INCOMING-COOKIES">crunch-incoming-cookies</a></tt>.
1803 Use <span class="emphasis EMPHASIS c2">both</span> to disable
1804 HTTP cookies completely.</p>
1806 <p>It makes <span class="emphasis EMPHASIS c2">no sense at
1807 all</span> to use this action in conjunction with the
1808 <tt class="LITERAL"><a href=
1809 "actions-file.html#SESSION-COOKIES-ONLY">session-cookies-only</a></tt>
1810 action, since it would prevent the session cookies from being
1814 <dt>Example usage:</dt>
1817 <table class="c4" border="0" width="90%">
1820 <pre class="SCREEN">
1821 +crunch-outgoing-cookies
1832 <h4 class="SECT3"><a name="DEANIMATE-GIFS" id=
1833 "DEANIMATE-GIFS">8.5.12. deanimate-gifs</a></h4>
1835 <div class="VARIABLELIST">
1837 <dt>Typical use:</dt>
1840 <p>Stop those annoying, distracting animated GIF images.</p>
1846 <p>De-animate GIF animations, i.e. reduce them to their first
1853 <p>Parameterized.</p>
1859 <p><span class="QUOTE">"last"</span> or <span class=
1860 "QUOTE">"first"</span></p>
1866 <p>This will also shrink the images considerably (in bytes, not
1867 pixels!). If the option <span class="QUOTE">"first"</span> is
1868 given, the first frame of the animation is used as the
1869 replacement. If <span class="QUOTE">"last"</span> is given, the
1870 last frame of the animation is used instead, which probably
1871 makes more sense for most banner animations, but also has the
1872 risk of not showing the entire last frame (if it is only a
1873 delta to an earlier frame).</p>
1875 <p>You can safely use this action with patterns that will also
1876 match non-GIF objects, because no attempt will be made at
1877 anything that doesn't look like a GIF.</p>
1880 <dt>Example usage:</dt>
1883 <table class="c4" border="0" width="90%">
1886 <pre class="SCREEN">
1887 +deanimate-gifs{last}
1898 <h4 class="SECT3"><a name="DOWNGRADE-HTTP-VERSION" id=
1899 "DOWNGRADE-HTTP-VERSION">8.5.13. downgrade-http-version</a></h4>
1901 <div class="VARIABLELIST">
1903 <dt>Typical use:</dt>
1906 <p>Work around (very rare) problems with HTTP/1.1</p>
1912 <p>Downgrades HTTP/1.1 client requests and server replies to
1931 <p>This is a left-over from the time when <span class=
1932 "APPLICATION">Privoxy</span> didn't support important HTTP/1.1
1933 features well. It is left here for the unlikely case that you
1934 experience HTTP/1.1-related problems with some server out
1937 <p>Note that enabling this action is only a workaround. It
1938 should not be enabled for sites that work without it. While it
1939 shouldn't break any pages, it has an (usually negative)
1940 performance impact.</p>
1942 <p>If you come across a site where enabling this action helps,
1943 please report it, so the cause of the problem can be analyzed.
1944 If the problem turns out to be caused by a bug in <span class=
1945 "APPLICATION">Privoxy</span> it should be fixed so the
1946 following release works without the work around.</p>
1949 <dt>Example usage (section):</dt>
1952 <table class="c4" border="0" width="90%">
1955 <pre class="SCREEN">
1956 {+downgrade-http-version}
1957 problem-host.example.com
1968 <h4 class="SECT3"><a name="FAST-REDIRECTS" id=
1969 "FAST-REDIRECTS">8.5.14. fast-redirects</a></h4>
1971 <div class="VARIABLELIST">
1973 <dt>Typical use:</dt>
1976 <p>Fool some click-tracking scripts and speed up indirect
1983 <p>Detects redirection URLs and redirects the browser without
1984 contacting the redirection server first.</p>
1990 <p>Parameterized.</p>
1998 <p><span class="QUOTE">"simple-check"</span> to just search
1999 for the string <span class="QUOTE">"http://"</span> to
2000 detect redirection URLs.</p>
2004 <p><span class="QUOTE">"check-decoded-url"</span> to decode
2005 URLs (if necessary) before searching for redirection
2014 <p>Many sites, like yahoo.com, don't just link to other sites.
2015 Instead, they will link to some script on their own servers,
2016 giving the destination as a parameter, which will then redirect
2017 you to the final target. URLs resulting from this scheme
2018 typically look like: <span class=
2019 "QUOTE">"http://www.example.org/click-tracker.cgi?target=http%3a//www.example.net/"</span>.</p>
2021 <p>Sometimes, there are even multiple consecutive redirects
2022 encoded in the URL. These redirections via scripts make your
2023 web browsing more traceable, since the server from which you
2024 follow such a link can see where you go to. Apart from that,
2025 valuable bandwidth and time is wasted, while your browser asks
2026 the server for one redirect after the other. Plus, it feeds the
2029 <p>This feature is currently not very smart and is scheduled
2030 for improvement. If it is enabled by default, you will have to
2031 create some exceptions to this action. It can lead to failures
2032 in several ways:</p>
2034 <p>Not every URLs with other URLs as parameters is evil. Some
2035 sites offer a real service that requires this information to
2036 work. For example a validation service needs to know, which
2037 document to validate. <tt class="LITERAL">fast-redirects</tt>
2038 assumes that every URL parameter that looks like another URL is
2039 a redirection target, and will always redirect to the last one.
2040 Most of the time the assumption is correct, but if it isn't,
2041 the user gets redirected anyway.</p>
2043 <p>Another failure occurs if the URL contains other parameters
2044 after the URL parameter. The URL: <span class=
2045 "QUOTE">"http://www.example.org/?redirect=http%3a//www.example.net/&foo=bar"</span>.
2046 contains the redirection URL <span class=
2047 "QUOTE">"http://www.example.net/"</span>, followed by another
2048 parameter. <tt class="LITERAL">fast-redirects</tt> doesn't know
2049 that and will cause a redirect to <span class=
2050 "QUOTE">"http://www.example.net/&foo=bar"</span>. Depending
2051 on the target server configuration, the parameter will be
2052 silently ignored or lead to a <span class="QUOTE">"page not
2053 found"</span> error. You can prevent this problem by first
2054 using the <tt class="LITERAL"><a href=
2055 "actions-file.html#REDIRECT">redirect</a></tt> action to remove
2056 the last part of the URL, but it requires a little effort.</p>
2058 <p>To detect a redirection URL, <tt class=
2059 "LITERAL">fast-redirects</tt> only looks for the string
2060 <span class="QUOTE">"http://"</span>, either in plain text
2061 (invalid but often used) or encoded as <span class=
2062 "QUOTE">"http%3a//"</span>. Some sites use their own URL
2063 encoding scheme, encrypt the address of the target server or
2064 replace it with a database id. In theses cases <tt class=
2065 "LITERAL">fast-redirects</tt> is fooled and the request reaches
2066 the redirection server where it probably gets logged.</p>
2069 <dt>Example usage:</dt>
2072 <table class="c4" border="0" width="90%">
2075 <pre class="SCREEN">
2076 { +fast-redirects{simple-check} }
2079 { +fast-redirects{check-decoded-url} }
2080 another.example.com/testing
2091 <h4 class="SECT3"><a name="FILTER" id="FILTER">8.5.15.
2094 <div class="VARIABLELIST">
2096 <dt>Typical use:</dt>
2099 <p>Get rid of HTML and JavaScript annoyances, banner
2100 advertisements (by size), do fun text replacements, add
2101 personalized effects, etc.</p>
2107 <p>All instances of text-based type, most notably HTML and
2108 JavaScript, to which this action applies, can be filtered
2109 on-the-fly through the specified regular expression based
2110 substitutions. (Note: as of version 3.0.3 plain text documents
2111 are exempted from filtering, because web servers often use the
2112 <tt class="LITERAL">text/plain</tt> MIME type for all files
2113 whose type they don't know.)</p>
2119 <p>Parameterized.</p>
2125 <p>The name of a content filter, as defined in the <a href=
2126 "filter-file.html">filter file</a>. Filters can be defined in
2127 one or more files as defined by the <tt class=
2128 "LITERAL"><a href="config.html#FILTERFILE">filterfile</a></tt>
2129 option in the <a href="config.html">config file</a>. <tt class=
2130 "FILENAME">default.filter</tt> is the collection of filters
2131 supplied by the developers. Locally defined filters should go
2132 in their own file, such as <tt class=
2133 "FILENAME">user.filter</tt>.</p>
2135 <p>When used in its negative form, and without parameters,
2136 <span class="emphasis EMPHASIS c2">all</span> filtering is
2137 completely disabled.</p>
2143 <p>For your convenience, there are a number of pre-defined
2144 filters available in the distribution filter file that you can
2145 use. See the examples below for a list.</p>
2147 <p>Filtering requires buffering the page content, which may
2148 appear to slow down page rendering since nothing is displayed
2149 until all content has passed the filters. (The total time until
2150 the page is completely rendered doesn't change much, but it may
2151 be perceived as slower since the page is not incrementally
2152 displayed.) This effect will be more noticeable on slower
2155 <p><span class="QUOTE">"Rolling your own"</span> filters
2156 requires a knowledge of <a href=
2157 "http://en.wikipedia.org/wiki/Regular_expressions" target=
2158 "_top"><span class="QUOTE">"Regular Expressions"</span></a> and
2159 <a href="http://en.wikipedia.org/wiki/Html" target=
2160 "_top"><span class="QUOTE">"HTML"</span></a>. This is very
2161 powerful feature, and potentially very intrusive. Filters
2162 should be used with caution, and where an equivalent
2163 <span class="QUOTE">"action"</span> is not available.</p>
2165 <p>The amount of data that can be filtered is limited to the
2166 <tt class="LITERAL"><a href=
2167 "config.html#BUFFER-LIMIT">buffer-limit</a></tt> option in the
2168 main <a href="config.html">config file</a>. The default is 4096
2169 KB (4 Megs). Once this limit is exceeded, the buffered data,
2170 and all pending data, is passed through unfiltered.</p>
2172 <p>Inappropriate MIME types, such as zipped files, are not
2173 filtered at all. (Again, only text-based types except plain
2174 text). Encrypted SSL data (from HTTPS servers) cannot be
2175 filtered either, since this would violate the integrity of the
2176 secure transaction. In some situations it might be necessary to
2177 protect certain text, like source code, from filtering by
2178 defining appropriate <tt class="LITERAL">-filter</tt>
2181 <p>Compressed content can't be filtered either, but if
2182 <span class="APPLICATION">Privoxy</span> is compiled with zlib
2183 support and a supported compression algorithm is used (gzip or
2184 deflate), <span class="APPLICATION">Privoxy</span> can first
2185 decompress the content and then filter it.</p>
2187 <p>If you use a <span class="APPLICATION">Privoxy</span>
2188 version without zlib support, but want filtering to work on as
2189 much documents as possible, even those that would normally be
2190 sent compressed, you must use the <tt class="LITERAL"><a href=
2191 "actions-file.html#PREVENT-COMPRESSION">prevent-compression</a></tt>
2192 action in conjunction with <tt class="LITERAL">filter</tt>.</p>
2194 <p>Content filtering can achieve some of the same effects as
2195 the <tt class="LITERAL"><a href=
2196 "actions-file.html#BLOCK">block</a></tt> action, i.e. it can be
2197 used to block ads and banners. But the mechanism works quite
2198 differently. One effective use, is to block ad banners based on
2199 their size (see below), since many of these seem to be somewhat
2202 <p><a href="contact.html">Feedback</a> with suggestions for new
2203 or improved filters is particularly welcome!</p>
2205 <p>The below list has only the names and a one-line description
2206 of each predefined filter. There are <a href=
2207 "filter-file.html#PREDEFINED-FILTERS">more verbose
2208 explanations</a> of what these filters do in the <a href=
2209 "filter-file.html">filter file chapter</a>.</p>
2212 <dt>Example usage (with filters from the distribution <tt class=
2213 "FILENAME">default.filter</tt> file). See <a href=
2214 "filter-file.html#PREDEFINED-FILTERS">the Predefined Filters
2215 section</a> for more explanation on each:</dt>
2218 <p><a name="FILTER-JS-ANNOYANCES" id=
2219 "FILTER-JS-ANNOYANCES"></a></p>
2221 <table class="c4" border="0" width="90%">
2224 <pre class="SCREEN">
2225 +filter{js-annoyances} # Get rid of particularly annoying JavaScript abuse.
2231 <p><a name="FILTER-JS-EVENTS" id="FILTER-JS-EVENTS"></a></p>
2233 <table class="c4" border="0" width="90%">
2236 <pre class="SCREEN">
2237 +filter{js-events} # Kill all JS event bindings and timers (Radically destructive! Only for extra nasty sites).
2243 <p><a name="FILTER-HTML-ANNOYANCES" id=
2244 "FILTER-HTML-ANNOYANCES"></a></p>
2246 <table class="c4" border="0" width="90%">
2249 <pre class="SCREEN">
2250 +filter{html-annoyances} # Get rid of particularly annoying HTML abuse.
2256 <p><a name="FILTER-CONTENT-COOKIES" id=
2257 "FILTER-CONTENT-COOKIES"></a></p>
2259 <table class="c4" border="0" width="90%">
2262 <pre class="SCREEN">
2263 +filter{content-cookies} # Kill cookies that come in the HTML or JS content.
2269 <p><a name="FILTER-REFRESH-TAGS" id=
2270 "FILTER-REFRESH-TAGS"></a></p>
2272 <table class="c4" border="0" width="90%">
2275 <pre class="SCREEN">
2276 +filter{refresh-tags} # Kill automatic refresh tags (for dial-on-demand setups).
2282 <p><a name="FILTER-UNSOLICITED-POPUPS" id=
2283 "FILTER-UNSOLICITED-POPUPS"></a></p>
2285 <table class="c4" border="0" width="90%">
2288 <pre class="SCREEN">
2289 +filter{unsolicited-popups} # Disable only unsolicited pop-up windows. Useful if your browser lacks this ability.
2295 <p><a name="FILTER-ALL-POPUPS" id="FILTER-ALL-POPUPS"></a></p>
2297 <table class="c4" border="0" width="90%">
2300 <pre class="SCREEN">
2301 +filter{all-popups} # Kill all popups in JavaScript and HTML. Useful if your browser lacks this ability.
2307 <p><a name="FILTER-IMG-REORDER" id=
2308 "FILTER-IMG-REORDER"></a></p>
2310 <table class="c4" border="0" width="90%">
2313 <pre class="SCREEN">
2314 +filter{img-reorder} # Reorder attributes in <img> tags to make the banners-by-* filters more effective.
2320 <p><a name="FILTER-BANNERS-BY-SIZE" id=
2321 "FILTER-BANNERS-BY-SIZE"></a></p>
2323 <table class="c4" border="0" width="90%">
2326 <pre class="SCREEN">
2327 +filter{banners-by-size} # Kill banners by size.
2333 <p><a name="FILTER-BANNERS-BY-LINK" id=
2334 "FILTER-BANNERS-BY-LINK"></a></p>
2336 <table class="c4" border="0" width="90%">
2339 <pre class="SCREEN">
2340 +filter{banners-by-link} # Kill banners by their links to known clicktrackers.
2346 <p><a name="FILTER-WEBBUGS" id="FILTER-WEBBUGS"></a></p>
2348 <table class="c4" border="0" width="90%">
2351 <pre class="SCREEN">
2352 +filter{webbugs} # Squish WebBugs (1x1 invisible GIFs used for user tracking).
2358 <p><a name="FILTER-TINY-TEXTFORMS" id=
2359 "FILTER-TINY-TEXTFORMS"></a></p>
2361 <table class="c4" border="0" width="90%">
2364 <pre class="SCREEN">
2365 +filter{tiny-textforms} # Extend those tiny textareas up to 40x80 and kill the hard wrap.
2371 <p><a name="FILTER-JUMPING-WINDOWS" id=
2372 "FILTER-JUMPING-WINDOWS"></a></p>
2374 <table class="c4" border="0" width="90%">
2377 <pre class="SCREEN">
2378 +filter{jumping-windows} # Prevent windows from resizing and moving themselves.
2384 <p><a name="FILTER-FRAMESET-BORDERS" id=
2385 "FILTER-FRAMESET-BORDERS"></a></p>
2387 <table class="c4" border="0" width="90%">
2390 <pre class="SCREEN">
2391 +filter{frameset-borders} # Give frames a border and make them resizable.
2397 <p><a name="FILTER-DEMORONIZER" id=
2398 "FILTER-DEMORONIZER"></a></p>
2400 <table class="c4" border="0" width="90%">
2403 <pre class="SCREEN">
2404 +filter{demoronizer} # Fix MS's non-standard use of standard charsets.
2410 <p><a name="FILTER-SHOCKWAVE-FLASH" id=
2411 "FILTER-SHOCKWAVE-FLASH"></a></p>
2413 <table class="c4" border="0" width="90%">
2416 <pre class="SCREEN">
2417 +filter{shockwave-flash} # Kill embedded Shockwave Flash objects.
2423 <p><a name="FILTER-QUICKTIME-KIOSKMODE" id=
2424 "FILTER-QUICKTIME-KIOSKMODE"></a></p>
2426 <table class="c4" border="0" width="90%">
2429 <pre class="SCREEN">
2430 +filter{quicktime-kioskmode} # Make Quicktime movies saveable.
2436 <p><a name="FILTER-FUN" id="FILTER-FUN"></a></p>
2438 <table class="c4" border="0" width="90%">
2441 <pre class="SCREEN">
2442 +filter{fun} # Text replacements for subversive browsing fun!
2448 <p><a name="FILTER-CRUDE-PARENTAL" id=
2449 "FILTER-CRUDE-PARENTAL"></a></p>
2451 <table class="c4" border="0" width="90%">
2454 <pre class="SCREEN">
2455 +filter{crude-parental} # Crude parental filtering. Note that this filter doesn't work reliably.
2461 <p><a name="FILTER-IE-EXPLOITS" id=
2462 "FILTER-IE-EXPLOITS"></a></p>
2464 <table class="c4" border="0" width="90%">
2467 <pre class="SCREEN">
2468 +filter{ie-exploits} # Disable some known Internet Explorer bug exploits.
2474 <p><a name="FILTER-SITE-SPECIFICS" id=
2475 "FILTER-SITE-SPECIFICS"></a></p>
2477 <table class="c4" border="0" width="90%">
2480 <pre class="SCREEN">
2481 +filter{site-specifics} # Cure for site-specific problems. Don't apply generally!
2487 <p><a name="FILTER-NO-PING" id="FILTER-NO-PING"></a></p>
2489 <table class="c4" border="0" width="90%">
2492 <pre class="SCREEN">
2493 +filter{no-ping} # Removes non-standard ping attributes in <a> and <area> tags.
2499 <p><a name="FILTER-GOOGLE" id="FILTER-GOOGLE"></a></p>
2501 <table class="c4" border="0" width="90%">
2504 <pre class="SCREEN">
2505 +filter{google} # CSS-based block for Google text ads. Also removes a width limitation and the toolbar advertisement.
2511 <p><a name="FILTER-YAHOO" id="FILTER-YAHOO"></a></p>
2513 <table class="c4" border="0" width="90%">
2516 <pre class="SCREEN">
2517 +filter{yahoo} # CSS-based block for Yahoo text ads. Also removes a width limitation.
2523 <p><a name="FILTER-MSN" id="FILTER-MSN"></a></p>
2525 <table class="c4" border="0" width="90%">
2528 <pre class="SCREEN">
2529 +filter{msn} # CSS-based block for MSN text ads. Also removes tracking URLs and a width limitation.
2535 <p><a name="FILTER-BLOGSPOT" id="FILTER-BLOGSPOT"></a></p>
2537 <table class="c4" border="0" width="90%">
2540 <pre class="SCREEN">
2541 +filter{blogspot} # Cleans up some Blogspot blogs. Read the fine print before using this.
2552 <h4 class="SECT3"><a name="FORCE-TEXT-MODE" id=
2553 "FORCE-TEXT-MODE">8.5.16. force-text-mode</a></h4>
2555 <div class="VARIABLELIST">
2557 <dt>Typical use:</dt>
2560 <p>Force <span class="APPLICATION">Privoxy</span> to treat a
2561 document as if it was in some kind of <span class=
2562 "emphasis EMPHASIS c2">text</span> format.</p>
2568 <p>Declares a document as text, even if the <span class=
2569 "QUOTE">"Content-Type:"</span> isn't detected as such.</p>
2587 <p>As explained <tt class="LITERAL"><a href=
2588 "actions-file.html#FILTER">above</a></tt>, <span class=
2589 "APPLICATION">Privoxy</span> tries to only filter files that
2590 are in some kind of text format. The same restrictions apply to
2591 <tt class="LITERAL"><a href=
2592 "actions-file.html#CONTENT-TYPE-OVERWRITE">content-type-overwrite</a></tt>.
2593 <tt class="LITERAL">force-text-mode</tt> declares a document as
2594 text, without looking at the <span class=
2595 "QUOTE">"Content-Type:"</span> first.</p>
2597 <div class="WARNING">
2598 <table class="WARNING" border="1" width="90%">
2600 <td class="c6" align="center">Warning</td>
2605 <p>Think twice before activating this action. Filtering
2606 binary data with regular expressions can cause file
2614 <dt>Example usage:</dt>
2617 <table class="c4" border="0" width="90%">
2620 <pre class="SCREEN">
2633 <h4 class="SECT3"><a name="FORWARD-OVERRIDE" id=
2634 "FORWARD-OVERRIDE">8.5.17. forward-override</a></h4>
2636 <div class="VARIABLELIST">
2638 <dt>Typical use:</dt>
2641 <p>Change the forwarding settings based on User-Agent or
2648 <p>Overrules the forward directives in the configuration
2663 <p><span class="QUOTE">"forward ."</span> to use a direct
2664 connection without any additional proxies.</p>
2668 <p><span class="QUOTE">"forward 127.0.0.1:8123"</span> to
2669 use the HTTP proxy listening at 127.0.0.1 port 8123.</p>
2673 <p><span class="QUOTE">"forward-socks4a 127.0.0.1:9050
2674 ."</span> to use the socks4a proxy listening at 127.0.0.1
2675 port 9050. Replace <span class=
2676 "QUOTE">"forward-socks4a"</span> with <span class=
2677 "QUOTE">"forward-socks4"</span> to use a socks4 connection
2678 (with local DNS resolution) instead, use <span class=
2679 "QUOTE">"forward-socks5"</span> for socks5 connections
2680 (with remote DNS resolution).</p>
2684 <p><span class="QUOTE">"forward-socks4a 127.0.0.1:9050
2685 proxy.example.org:8000"</span> to use the socks4a proxy
2686 listening at 127.0.0.1 port 9050 to reach the HTTP proxy
2687 listening at proxy.example.org port 8000. Replace
2688 <span class="QUOTE">"forward-socks4a"</span> with
2689 <span class="QUOTE">"forward-socks4"</span> to use a socks4
2690 connection (with local DNS resolution) instead, use
2691 <span class="QUOTE">"forward-socks5"</span> for socks5
2692 connections (with remote DNS resolution).</p>
2700 <p>This action takes parameters similar to the <a href=
2701 "config.html#FORWARDING">forward</a> directives in the
2702 configuration file, but without the URL pattern. It can be used
2703 as replacement, but normally it's only used in cases where
2704 matching based on the request URL isn't sufficient.</p>
2706 <div class="WARNING">
2707 <table class="WARNING" border="1" width="90%">
2709 <td class="c6" align="center">Warning</td>
2714 <p>Please read the description for the <a href=
2715 "config.html#FORWARDING">forward</a> directives before
2716 using this action. Forwarding to the wrong people will
2717 reduce your privacy and increase the chances of
2718 man-in-the-middle attacks.</p>
2720 <p>If the ports are missing or invalid, default values
2721 will be used. This might change in the future and you
2722 shouldn't rely on it. Otherwise incorrect syntax causes
2723 Privoxy to exit.</p>
2726 "http://config.privoxy.org/show-url-info" target=
2727 "_top">show-url-info CGI page</a> to verify that your
2728 forward settings do what you thought the do.</p>
2735 <dt>Example usage:</dt>
2738 <table class="c4" border="0" width="90%">
2741 <pre class="SCREEN">
2742 # Always use direct connections for requests previously tagged as
2743 # <span class="QUOTE">"User-Agent: fetch libfetch/2.0"</span> and make sure
2744 # resuming downloads continues to work.
2745 # This way you can continue to use Tor for your normal browsing,
2746 # without overloading the Tor network with your FreeBSD ports updates
2747 # or downloads of bigger files like ISOs.
2748 # Note that HTTP headers are easy to fake and therefore their
2749 # values are as (un)trustworthy as your clients and users.
2750 {+forward-override{forward .} \
2751 -hide-if-modified-since \
2752 -overwrite-last-modified \
2754 TAG:^User-Agent: fetch libfetch/2\.0$
2766 <h4 class="SECT3"><a name="HANDLE-AS-EMPTY-DOCUMENT" id=
2767 "HANDLE-AS-EMPTY-DOCUMENT">8.5.18. handle-as-empty-document</a></h4>
2769 <div class="VARIABLELIST">
2771 <dt>Typical use:</dt>
2774 <p>Mark URLs that should be replaced by empty documents
2775 <span class="emphasis EMPHASIS c2">if they get
2782 <p>This action alone doesn't do anything noticeable. It just
2783 marks URLs. If the <tt class="LITERAL"><a href=
2784 "actions-file.html#BLOCK">block</a></tt> action <span class=
2785 "emphasis EMPHASIS c2">also applies</span>, the presence or
2786 absence of this mark decides whether an HTML <span class=
2787 "QUOTE">"BLOCKED"</span> page, or an empty document will be
2788 sent to the client as a substitute for the blocked content. The
2789 <span class="emphasis EMPHASIS c2">empty</span> document isn't
2790 literally empty, but actually contains a single space.</p>
2808 <p>Some browsers complain about syntax errors if JavaScript
2809 documents are blocked with <span class=
2810 "APPLICATION">Privoxy's</span> default HTML page; this option
2811 can be used to silence them. And of course this action can also
2812 be used to eliminate the <span class=
2813 "APPLICATION">Privoxy</span> BLOCKED message in frames.</p>
2815 <p>The content type for the empty document can be specified
2816 with <tt class="LITERAL"><a href=
2817 "actions-file.html#CONTENT-TYPE-OVERWRITE">content-type-overwrite{}</a></tt>,
2818 but usually this isn't necessary.</p>
2821 <dt>Example usage:</dt>
2824 <table class="c4" border="0" width="90%">
2827 <pre class="SCREEN">
2828 # Block all documents on example.org that end with ".js",
2829 # but send an empty document instead of the usual HTML message.
2830 {+block{Blocked JavaScript} +handle-as-empty-document}
2843 <h4 class="SECT3"><a name="HANDLE-AS-IMAGE" id=
2844 "HANDLE-AS-IMAGE">8.5.19. handle-as-image</a></h4>
2846 <div class="VARIABLELIST">
2848 <dt>Typical use:</dt>
2851 <p>Mark URLs as belonging to images (so they'll be replaced by
2852 images <span class="emphasis EMPHASIS c2">if they do get
2853 blocked</span>, rather than HTML pages)</p>
2859 <p>This action alone doesn't do anything noticeable. It just
2860 marks URLs as images. If the <tt class="LITERAL"><a href=
2861 "actions-file.html#BLOCK">block</a></tt> action <span class=
2862 "emphasis EMPHASIS c2">also applies</span>, the presence or
2863 absence of this mark decides whether an HTML <span class=
2864 "QUOTE">"blocked"</span> page, or a replacement image (as
2865 determined by the <tt class="LITERAL"><a href=
2866 "actions-file.html#SET-IMAGE-BLOCKER">set-image-blocker</a></tt>
2867 action) will be sent to the client as a substitute for the
2868 blocked content.</p>
2886 <p>The below generic example section is actually part of
2887 <tt class="FILENAME">default.action</tt>. It marks all URLs
2888 with well-known image file name extensions as images and should
2891 <p>Users will probably only want to use the handle-as-image
2892 action in conjunction with <tt class="LITERAL"><a href=
2893 "actions-file.html#BLOCK">block</a></tt>, to block sources of
2894 banners, whose URLs don't reflect the file type, like in the
2895 second example section.</p>
2897 <p>Note that you cannot treat HTML pages as images in most
2898 cases. For instance, (in-line) ad frames require an HTML page
2899 to be sent, or they won't display properly. Forcing <tt class=
2900 "LITERAL">handle-as-image</tt> in this situation will not
2901 replace the ad frame with an image, but lead to error
2905 <dt>Example usage (sections):</dt>
2908 <table class="c4" border="0" width="90%">
2911 <pre class="SCREEN">
2912 # Generic image extensions:
2915 /.*\.(gif|jpg|jpeg|png|bmp|ico)$
2917 # These don't look like images, but they're banners and should be
2918 # blocked as images:
2920 {+block{Nasty banners.} +handle-as-image}
2921 nasty-banner-server.example.com/junk.cgi\?output=trash
2932 <h4 class="SECT3"><a name="HIDE-ACCEPT-LANGUAGE" id=
2933 "HIDE-ACCEPT-LANGUAGE">8.5.20. hide-accept-language</a></h4>
2935 <div class="VARIABLELIST">
2937 <dt>Typical use:</dt>
2940 <p>Pretend to use different language settings.</p>
2946 <p>Deletes or replaces the <span class=
2947 "QUOTE">"Accept-Language:"</span> HTTP header in client
2954 <p>Parameterized.</p>
2960 <p>Keyword: <span class="QUOTE">"block"</span>, or any user
2967 <p>Faking the browser's language settings can be useful to make
2968 a foreign User-Agent set with <tt class="LITERAL"><a href=
2969 "actions-file.html#HIDE-USER-AGENT">hide-user-agent</a></tt>
2970 more believable.</p>
2972 <p>However some sites with content in different languages check
2973 the <span class="QUOTE">"Accept-Language:"</span> to decide
2974 which one to take by default. Sometimes it isn't possible to
2975 later switch to another language without changing the
2976 <span class="QUOTE">"Accept-Language:"</span> header first.</p>
2978 <p>Therefore it's a good idea to either only change the
2979 <span class="QUOTE">"Accept-Language:"</span> header to
2980 languages you understand, or to languages that aren't wide
2983 <p>Before setting the <span class=
2984 "QUOTE">"Accept-Language:"</span> header to a rare language,
2985 you should consider that it helps to make your requests unique
2986 and thus easier to trace. If you don't plan to change this
2987 header frequently, you should stick to a common language.</p>
2990 <dt>Example usage (section):</dt>
2993 <table class="c4" border="0" width="90%">
2996 <pre class="SCREEN">
2997 # Pretend to use Canadian language settings.
2998 {+hide-accept-language{en-ca} \
2999 +hide-user-agent{Mozilla/5.0 (X11; U; OpenBSD i386; en-CA; rv:1.8.0.4) Gecko/20060628 Firefox/1.5.0.4} \
3012 <h4 class="SECT3"><a name="HIDE-CONTENT-DISPOSITION" id=
3013 "HIDE-CONTENT-DISPOSITION">8.5.21. hide-content-disposition</a></h4>
3015 <div class="VARIABLELIST">
3017 <dt>Typical use:</dt>
3020 <p>Prevent download menus for content you prefer to view inside
3027 <p>Deletes or replaces the <span class=
3028 "QUOTE">"Content-Disposition:"</span> HTTP header set by some
3035 <p>Parameterized.</p>
3041 <p>Keyword: <span class="QUOTE">"block"</span>, or any user
3048 <p>Some servers set the <span class=
3049 "QUOTE">"Content-Disposition:"</span> HTTP header for documents
3050 they assume you want to save locally before viewing them. The
3051 <span class="QUOTE">"Content-Disposition:"</span> header
3052 contains the file name the browser is supposed to use by
3055 <p>In most browsers that understand this header, it makes it
3056 impossible to <span class="emphasis EMPHASIS c2">just
3057 view</span> the document, without downloading it first, even if
3058 it's just a simple text file or an image.</p>
3060 <p>Removing the <span class=
3061 "QUOTE">"Content-Disposition:"</span> header helps to prevent
3062 this annoyance, but some browsers additionally check the
3063 <span class="QUOTE">"Content-Type:"</span> header, before they
3064 decide if they can display a document without saving it first.
3065 In these cases, you have to change this header as well, before
3066 the browser stops displaying download menus.</p>
3068 <p>It is also possible to change the server's file name
3069 suggestion to another one, but in most cases it isn't worth the
3070 time to set it up.</p>
3072 <p>This action will probably be removed in the future, use
3073 server-header filters instead.</p>
3076 <dt>Example usage:</dt>
3079 <table class="c4" border="0" width="90%">
3082 <pre class="SCREEN">
3083 # Disarm the download link in Sourceforge's patch tracker
3085 +content-type-overwrite{text/plain}\
3086 +hide-content-disposition{block} }
3087 .sourceforge.net/tracker/download\.php
3098 <h4 class="SECT3"><a name="HIDE-IF-MODIFIED-SINCE" id=
3099 "HIDE-IF-MODIFIED-SINCE">8.5.22. hide-if-modified-since</a></h4>
3101 <div class="VARIABLELIST">
3103 <dt>Typical use:</dt>
3106 <p>Prevent yet another way to track the user's steps between
3113 <p>Deletes the <span class="QUOTE">"If-Modified-Since:"</span>
3114 HTTP client header or modifies its value.</p>
3120 <p>Parameterized.</p>
3126 <p>Keyword: <span class="QUOTE">"block"</span>, or a user
3127 defined value that specifies a range of hours.</p>
3133 <p>Removing this header is useful for filter testing, where you
3134 want to force a real reload instead of getting status code
3135 <span class="QUOTE">"304"</span>, which would cause the browser
3136 to use a cached copy of the page.</p>
3138 <p>Instead of removing the header, <tt class=
3139 "LITERAL">hide-if-modified-since</tt> can also add or subtract
3140 a random amount of time to/from the header's value. You specify
3141 a range of minutes where the random factor should be chosen
3142 from and <span class="APPLICATION">Privoxy</span> does the
3143 rest. A negative value means subtracting, a positive value
3146 <p>Randomizing the value of the <span class=
3147 "QUOTE">"If-Modified-Since:"</span> makes it less likely that
3148 the server can use the time as a cookie replacement, but you
3149 will run into caching problems if the random range is too
3152 <p>It is a good idea to only use a small negative value and let
3153 <tt class="LITERAL"><a href=
3154 "actions-file.html#OVERWRITE-LAST-MODIFIED">overwrite-last-modified</a></tt>
3155 handle the greater changes.</p>
3157 <p>It is also recommended to use this action together with
3158 <tt class="LITERAL"><a href=
3159 "actions-file.html#CRUNCH-IF-NONE-MATCH">crunch-if-none-match</a></tt>,
3160 otherwise it's more or less pointless.</p>
3163 <dt>Example usage (section):</dt>
3166 <table class="c4" border="0" width="90%">
3169 <pre class="SCREEN">
3170 # Let the browser revalidate but make tracking based on the time less likely.
3171 {+hide-if-modified-since{-60} \
3172 +overwrite-last-modified{randomize} \
3173 +crunch-if-none-match}
3185 <h4 class="SECT3"><a name="HIDE-FROM-HEADER" id=
3186 "HIDE-FROM-HEADER">8.5.23. hide-from-header</a></h4>
3188 <div class="VARIABLELIST">
3190 <dt>Typical use:</dt>
3193 <p>Keep your (old and ill) browser from telling web servers
3194 your email address</p>
3200 <p>Deletes any existing <span class="QUOTE">"From:"</span> HTTP
3201 header, or replaces it with the specified string.</p>
3207 <p>Parameterized.</p>
3213 <p>Keyword: <span class="QUOTE">"block"</span>, or any user
3220 <p>The keyword <span class="QUOTE">"block"</span> will
3221 completely remove the header (not to be confused with the
3222 <tt class="LITERAL"><a href=
3223 "actions-file.html#BLOCK">block</a></tt> action).</p>
3225 <p>Alternately, you can specify any value you prefer to be sent
3226 to the web server. If you do, it is a matter of fairness not to
3227 use any address that is actually used by a real person.</p>
3229 <p>This action is rarely needed, as modern web browsers don't
3230 send <span class="QUOTE">"From:"</span> headers anymore.</p>
3233 <dt>Example usage:</dt>
3236 <table class="c4" border="0" width="90%">
3239 <pre class="SCREEN">
3240 +hide-from-header{block}
3246 <table class="c4" border="0" width="90%">
3249 <pre class="SCREEN">
3250 +hide-from-header{spam-me-senseless@sittingduck.example.com}
3261 <h4 class="SECT3"><a name="HIDE-REFERRER" id="HIDE-REFERRER">8.5.24.
3262 hide-referrer</a></h4><a name="HIDE-REFERER" id="HIDE-REFERER"></a>
3264 <div class="VARIABLELIST">
3266 <dt>Typical use:</dt>
3269 <p>Conceal which link you followed to get to a particular
3276 <p>Deletes the <span class="QUOTE">"Referer:"</span> (sic) HTTP
3277 header from the client request, or replaces it with a forged
3284 <p>Parameterized.</p>
3292 <p><span class="QUOTE">"conditional-block"</span> to delete
3293 the header completely if the host has changed.</p>
3297 <p><span class="QUOTE">"conditional-forge"</span> to forge
3298 the header if the host has changed.</p>
3302 <p><span class="QUOTE">"block"</span> to delete the header
3303 unconditionally.</p>
3307 <p><span class="QUOTE">"forge"</span> to pretend to be
3308 coming from the homepage of the server we are talking
3313 <p>Any other string to set a user defined referrer.</p>
3321 <p><tt class="LITERAL">conditional-block</tt> is the only
3322 parameter, that isn't easily detected in the server's log file.
3323 If it blocks the referrer, the request will look like the
3324 visitor used a bookmark or typed in the address directly.</p>
3326 <p>Leaving the referrer unmodified for requests on the same
3327 host allows the server owner to see the visitor's <span class=
3328 "QUOTE">"click path"</span>, but in most cases she could also
3329 get that information by comparing other parts of the log file:
3330 for example the User-Agent if it isn't a very common one, or
3331 the user's IP address if it doesn't change between different
3334 <p>Always blocking the referrer, or using a custom one, can
3335 lead to failures on servers that check the referrer before they
3336 answer any requests, in an attempt to prevent their content
3337 from being embedded or linked to elsewhere.</p>
3339 <p>Both <tt class="LITERAL">conditional-block</tt> and
3340 <tt class="LITERAL">forge</tt> will work with referrer checks,
3341 as long as content and valid referring page are on the same
3342 host. Most of the time that's the case.</p>
3344 <p><tt class="LITERAL">hide-referer</tt> is an alternate
3345 spelling of <tt class="LITERAL">hide-referrer</tt> and the two
3346 can be can be freely substituted with each other. (<span class=
3347 "QUOTE">"referrer"</span> is the correct English spelling,
3348 however the HTTP specification has a bug - it requires it to be
3349 spelled as <span class="QUOTE">"referer"</span>.)</p>
3352 <dt>Example usage:</dt>
3355 <table class="c4" border="0" width="90%">
3358 <pre class="SCREEN">
3359 +hide-referrer{forge}
3365 <table class="c4" border="0" width="90%">
3368 <pre class="SCREEN">
3369 +hide-referrer{http://www.yahoo.com/}
3380 <h4 class="SECT3"><a name="HIDE-USER-AGENT" id=
3381 "HIDE-USER-AGENT">8.5.25. hide-user-agent</a></h4>
3383 <div class="VARIABLELIST">
3385 <dt>Typical use:</dt>
3388 <p>Try to conceal your type of browser and client operating
3395 <p>Replaces the value of the <span class=
3396 "QUOTE">"User-Agent:"</span> HTTP header in client requests
3397 with the specified value.</p>
3403 <p>Parameterized.</p>
3409 <p>Any user-defined string.</p>
3415 <div class="WARNING">
3416 <table class="WARNING" border="1" width="90%">
3418 <td class="c6" align="center">Warning</td>
3423 <p>This can lead to problems on web sites that depend
3424 on looking at this header in order to customize their
3425 content for different browsers (which, by the way, is
3426 <span class="emphasis EMPHASIS c2">NOT</span> the right
3427 thing to do: good web sites work
3428 browser-independently).</p>
3434 <p>Using this action in multi-user setups or wherever different
3435 types of browsers will access the same <span class=
3436 "APPLICATION">Privoxy</span> is <span class=
3437 "emphasis EMPHASIS c2">not recommended</span>. In single-user,
3438 single-browser setups, you might use it to delete your OS
3439 version information from the headers, because it is an
3440 invitation to exploit known bugs for your OS. It is also
3441 occasionally useful to forge this in order to access sites that
3442 won't let you in otherwise (though there may be a good reason
3445 <p>More information on known user-agent strings can be found at
3446 <a href="http://www.user-agents.org/" target=
3447 "_top">http://www.user-agents.org/</a> and <a href=
3448 "http://en.wikipedia.org/wiki/User_agent" target=
3449 "_top">http://en.wikipedia.org/wiki/User_agent</a>.</p>
3452 <dt>Example usage:</dt>
3455 <table class="c4" border="0" width="90%">
3458 <pre class="SCREEN">
3459 +hide-user-agent{Netscape 6.1 (X11; I; Linux 2.4.18 i686)}
3470 <h4 class="SECT3"><a name="LIMIT-CONNECT" id="LIMIT-CONNECT">8.5.26.
3471 limit-connect</a></h4>
3473 <div class="VARIABLELIST">
3475 <dt>Typical use:</dt>
3478 <p>Prevent abuse of <span class="APPLICATION">Privoxy</span> as
3479 a TCP proxy relay or disable SSL for untrusted sites</p>
3485 <p>Specifies to which ports HTTP CONNECT requests are
3492 <p>Parameterized.</p>
3498 <p>A comma-separated list of ports or port ranges (the latter
3499 using dashes, with the minimum defaulting to 0 and the maximum
3506 <p>By default, i.e. if no <tt class=
3507 "LITERAL">limit-connect</tt> action applies, <span class=
3508 "APPLICATION">Privoxy</span> allows HTTP CONNECT requests to
3509 all ports. Use <tt class="LITERAL">limit-connect</tt> if
3510 fine-grained control is desired for some or all
3513 <p>The CONNECT methods exists in HTTP to allow access to secure
3514 websites (<span class="QUOTE">"https://"</span> URLs) through
3515 proxies. It works very simply: the proxy connects to the server
3516 on the specified port, and then short-circuits its connections
3517 to the client and to the remote server. This means
3518 CONNECT-enabled proxies can be used as TCP relays very
3521 <p><span class="APPLICATION">Privoxy</span> relays HTTPS
3522 traffic without seeing the decoded content. Websites can
3523 leverage this limitation to circumvent <span class=
3524 "APPLICATION">Privoxy</span>'s filters. By specifying an
3525 invalid port range you can disable HTTPS entirely.</p>
3528 <dt>Example usages:</dt>
3531 <table class="c4" border="0" width="90%">
3534 <pre class="SCREEN">
3535 +limit-connect{443} # Port 443 is OK.
3536 +limit-connect{80,443} # Ports 80 and 443 are OK.
3537 +limit-connect{-3, 7, 20-100, 500-} # Ports less than 3, 7, 20 to 100 and above 500 are OK.
3538 +limit-connect{-} # All ports are OK
3539 +limit-connect{,} # No HTTPS/SSL traffic is allowed
3550 <h4 class="SECT3"><a name="PREVENT-COMPRESSION" id=
3551 "PREVENT-COMPRESSION">8.5.27. prevent-compression</a></h4>
3553 <div class="VARIABLELIST">
3555 <dt>Typical use:</dt>
3558 <p>Ensure that servers send the content uncompressed, so it can
3559 be passed through <tt class="LITERAL"><a href=
3560 "actions-file.html#FILTER">filter</a></tt>s.</p>
3566 <p>Removes the Accept-Encoding header which can be used to ask
3567 for compressed transfer.</p>
3585 <p>More and more websites send their content compressed by
3586 default, which is generally a good idea and saves bandwidth.
3587 But the <tt class="LITERAL"><a href=
3588 "actions-file.html#FILTER">filter</a></tt> and <tt class=
3590 "actions-file.html#DEANIMATE-GIFS">deanimate-gifs</a></tt>
3591 actions need access to the uncompressed data.</p>
3593 <p>When compiled with zlib support (available since
3594 <span class="APPLICATION">Privoxy</span> 3.0.7), content that
3595 should be filtered is decompressed on-the-fly and you don't
3596 have to worry about this action. If you are using an older
3597 <span class="APPLICATION">Privoxy</span> version, or one that
3598 hasn't been compiled with zlib support, this action can be used
3599 to convince the server to send the content uncompressed.</p>
3601 <p>Most text-based instances compress very well, the size is
3602 seldom decreased by less than 50%, for markup-heavy instances
3603 like news feeds saving more than 90% of the original size isn't
3606 <p>Not using compression will therefore slow down the transfer,
3607 and you should only enable this action if you really need it.
3608 As of <span class="APPLICATION">Privoxy</span> 3.0.7 it's
3609 disabled in all predefined action settings.</p>
3611 <p>Note that some (rare) ill-configured sites don't handle
3612 requests for uncompressed documents correctly. Broken PHP
3613 applications tend to send an empty document body, some IIS
3614 versions only send the beginning of the content. If you enable
3615 <tt class="LITERAL">prevent-compression</tt> per default, you
3616 might want to add exceptions for those sites. See the example
3617 for how to do that.</p>
3620 <dt>Example usage (sections):</dt>
3623 <table class="c4" border="0" width="90%">
3626 <pre class="SCREEN">
3627 # Selectively turn off compression, and enable a filter
3629 { +filter{tiny-textforms} +prevent-compression }
3630 # Match only these sites
3635 # Or instead, we could set a universal default:
3637 { +prevent-compression }
3640 # Then maybe make exceptions for broken sites:
3642 { -prevent-compression }
3654 <h4 class="SECT3"><a name="OVERWRITE-LAST-MODIFIED" id=
3655 "OVERWRITE-LAST-MODIFIED">8.5.28. overwrite-last-modified</a></h4>
3657 <div class="VARIABLELIST">
3659 <dt>Typical use:</dt>
3662 <p>Prevent yet another way to track the user's steps between
3669 <p>Deletes the <span class="QUOTE">"Last-Modified:"</span> HTTP
3670 server header or modifies its value.</p>
3676 <p>Parameterized.</p>
3682 <p>One of the keywords: <span class="QUOTE">"block"</span>,
3683 <span class="QUOTE">"reset-to-request-time"</span> and
3684 <span class="QUOTE">"randomize"</span></p>
3690 <p>Removing the <span class="QUOTE">"Last-Modified:"</span>
3691 header is useful for filter testing, where you want to force a
3692 real reload instead of getting status code <span class=
3693 "QUOTE">"304"</span>, which would cause the browser to reuse
3694 the old version of the page.</p>
3696 <p>The <span class="QUOTE">"randomize"</span> option overwrites
3697 the value of the <span class="QUOTE">"Last-Modified:"</span>
3698 header with a randomly chosen time between the original value
3699 and the current time. In theory the server could send each
3700 document with a different <span class=
3701 "QUOTE">"Last-Modified:"</span> header to track visits without
3702 using cookies. <span class="QUOTE">"Randomize"</span> makes it
3703 impossible and the browser can still revalidate cached
3706 <p><span class="QUOTE">"reset-to-request-time"</span>
3707 overwrites the value of the <span class=
3708 "QUOTE">"Last-Modified:"</span> header with the current time.
3709 You could use this option together with <tt class=
3711 "actions-file.html#HIDE-IF-MODIFIED-SINCE">hide-if-modified-since</a></tt>
3712 to further customize your random range.</p>
3714 <p>The preferred parameter here is <span class=
3715 "QUOTE">"randomize"</span>. It is safe to use, as long as the
3716 time settings are more or less correct. If the server sets the
3717 <span class="QUOTE">"Last-Modified:"</span> header to the time
3718 of the request, the random range becomes zero and the value
3719 stays the same. Therefore you should later randomize it a
3720 second time with <tt class="LITERAL"><a href=
3721 "actions-file.html#HIDE-IF-MODIFIED-SINCE">hided-if-modified-since</a></tt>,
3722 just to be sure.</p>
3724 <p>It is also recommended to use this action together with
3725 <tt class="LITERAL"><a href=
3726 "actions-file.html#CRUNCH-IF-NONE-MATCH">crunch-if-none-match</a></tt>.</p>
3729 <dt>Example usage:</dt>
3732 <table class="c4" border="0" width="90%">
3735 <pre class="SCREEN">
3736 # Let the browser revalidate without being tracked across sessions
3737 { +hide-if-modified-since{-60} \
3738 +overwrite-last-modified{randomize} \
3739 +crunch-if-none-match}
3751 <h4 class="SECT3"><a name="REDIRECT" id="REDIRECT">8.5.29.
3754 <div class="VARIABLELIST">
3756 <dt>Typical use:</dt>
3759 <p>Redirect requests to other sites.</p>
3765 <p>Convinces the browser that the requested document has been
3766 moved to another location and the browser should get it from
3773 <p>Parameterized</p>
3779 <p>An absolute URL or a single pcrs command.</p>
3785 <p>Requests to which this action applies are answered with a
3786 HTTP redirect to URLs of your choosing. The new URL is either
3787 provided as parameter, or derived by applying a single pcrs
3788 command to the original URL.</p>
3790 <p>This action will be ignored if you use it together with
3791 <tt class="LITERAL"><a href=
3792 "actions-file.html#BLOCK">block</a></tt>. It can be combined
3793 with <tt class="LITERAL"><a href=
3794 "actions-file.html#FAST-REDIRECTS">fast-redirects{check-decoded-url}</a></tt>
3795 to redirect to a decoded version of a rewritten URL.</p>
3797 <p>Use this action carefully, make sure not to create
3798 redirection loops and be aware that using your own redirects
3799 might make it possible to fingerprint your requests.</p>
3801 <p>In case of problems with your redirects, or simply to watch
3802 them working, enable <a href="config.html#DEBUG">debug
3806 <dt>Example usages:</dt>
3809 <table class="c4" border="0" width="90%">
3812 <pre class="SCREEN">
3813 # Replace example.com's style sheet with another one
3814 { +redirect{http://localhost/css-replacements/example.com.css} }
3815 example.com/stylesheet\.css
3817 # Create a short, easy to remember nickname for a favorite site
3818 # (relies on the browser accept and forward invalid URLs to <span class=
3819 "APPLICATION">Privoxy</span>)
3820 { +redirect{http://www.privoxy.org/user-manual/actions-file.html} }
3823 # Always use the expanded view for Undeadly.org articles
3824 # (Note the $ at the end of the URL pattern to make sure
3825 # the request for the rewritten URL isn't redirected as well)
3826 {+redirect{s@$@&mode=expanded@}}
3827 undeadly.org/cgi\?action=article&sid=\d*$
3829 # Redirect Google search requests to MSN
3830 {+redirect{s@^http://[^/]*/search\?q=([^&]*).*@http://search.msn.com/results.aspx?q=$1@}}
3833 # Redirect MSN search requests to Yahoo
3834 {+redirect{s@^http://[^/]*/results\.aspx\?q=([^&]*).*@http://search.yahoo.com/search?p=$1@}}
3835 search.msn.com//results\.aspx\?q=
3837 # Redirect remote requests for this manual
3838 # to the local version delivered by Privoxy
3839 {+redirect{s@^http://www@http://config@}}
3840 www.privoxy.org/user-manual/
3851 <h4 class="SECT3"><a name="SERVER-HEADER-FILTER" id=
3852 "SERVER-HEADER-FILTER">8.5.30. server-header-filter</a></h4>
3854 <div class="VARIABLELIST">
3856 <dt>Typical use:</dt>
3859 <p>Rewrite or remove single server headers.</p>
3865 <p>All server headers to which this action applies are filtered
3866 on-the-fly through the specified regular expression based
3873 <p>Parameterized.</p>
3879 <p>The name of a server-header filter, as defined in one of the
3880 <a href="filter-file.html">filter files</a>.</p>
3886 <p>Server-header filters are applied to each header on its own,
3887 not to all at once. This makes it easier to diagnose problems,
3888 but on the downside you can't write filters that only change
3889 header x if header y's value is z. You can do that by using
3892 <p>Server-header filters are executed after the other header
3893 actions have finished and use their output as input.</p>
3895 <p>Please refer to the <a href="filter-file.html">filter file
3896 chapter</a> to learn which server-header filters are available
3897 by default, and how to create your own.</p>
3900 <dt>Example usage (section):</dt>
3903 <table class="c4" border="0" width="90%">
3906 <pre class="SCREEN">
3907 {+server-header-filter{html-to-xml}}
3908 example.org/xml-instance-that-is-delivered-as-html
3910 {+server-header-filter{xml-to-html}}
3911 example.org/instance-that-is-delivered-as-xml-but-is-not
3923 <h4 class="SECT3"><a name="SERVER-HEADER-TAGGER" id=
3924 "SERVER-HEADER-TAGGER">8.5.31. server-header-tagger</a></h4>
3926 <div class="VARIABLELIST">
3928 <dt>Typical use:</dt>
3931 <p>Enable or disable filters based on the Content-Type
3938 <p>Server headers to which this action applies are filtered
3939 on-the-fly through the specified regular expression based
3940 substitutions, the result is used as tag.</p>
3946 <p>Parameterized.</p>
3952 <p>The name of a server-header tagger, as defined in one of the
3953 <a href="filter-file.html">filter files</a>.</p>
3959 <p>Server-header taggers are applied to each header on its own,
3960 and as the header isn't modified, each tagger <span class=
3961 "QUOTE">"sees"</span> the original.</p>
3963 <p>Server-header taggers are executed before all other header
3964 actions that modify server headers. Their tags can be used to
3965 control all of the other server-header actions, the content
3966 filters and the crunch actions (<a href=
3967 "actions-file.html#REDIRECT">redirect</a> and <a href=
3968 "actions-file.html#BLOCK">block</a>).</p>
3970 <p>Obviously crunching based on tags created by server-header
3971 taggers doesn't prevent the request from showing up in the
3972 server's log file.</p>
3975 <dt>Example usage (section):</dt>
3978 <table class="c4" border="0" width="90%">
3981 <pre class="SCREEN">
3982 # Tag every request with the content type declared by the server
3983 {+server-header-tagger{content-type}}
3996 <h4 class="SECT3"><a name="SESSION-COOKIES-ONLY" id=
3997 "SESSION-COOKIES-ONLY">8.5.32. session-cookies-only</a></h4>
3999 <div class="VARIABLELIST">
4001 <dt>Typical use:</dt>
4004 <p>Allow only temporary <span class="QUOTE">"session"</span>
4005 cookies (for the current browser session <span class=
4006 "emphasis EMPHASIS c2">only</span>).</p>
4012 <p>Deletes the <span class="QUOTE">"expires"</span> field from
4013 <span class="QUOTE">"Set-Cookie:"</span> server headers. Most
4014 browsers will not store such cookies permanently and forget
4015 them in between sessions.</p>
4033 <p>This is less strict than <tt class="LITERAL"><a href=
4034 "actions-file.html#CRUNCH-INCOMING-COOKIES">crunch-incoming-cookies</a></tt>
4035 / <tt class="LITERAL"><a href=
4036 "actions-file.html#CRUNCH-OUTGOING-COOKIES">crunch-outgoing-cookies</a></tt>
4037 and allows you to browse websites that insist or rely on
4038 setting cookies, without compromising your privacy too
4041 <p>Most browsers will not permanently store cookies that have
4042 been processed by <tt class="LITERAL">session-cookies-only</tt>
4043 and will forget about them between sessions. This makes
4044 profiling cookies useless, but won't break sites which require
4045 cookies so that you can log in for transactions. This is
4046 generally turned on for all sites, and is the recommended
4049 <p>It makes <span class="emphasis EMPHASIS c2">no sense at
4050 all</span> to use <tt class="LITERAL">session-cookies-only</tt>
4051 together with <tt class="LITERAL"><a href=
4052 "actions-file.html#CRUNCH-INCOMING-COOKIES">crunch-incoming-cookies</a></tt>
4053 or <tt class="LITERAL"><a href=
4054 "actions-file.html#CRUNCH-OUTGOING-COOKIES">crunch-outgoing-cookies</a></tt>.
4055 If you do, cookies will be plainly killed.</p>
4057 <p>Note that it is up to the browser how it handles such
4058 cookies without an <span class="QUOTE">"expires"</span> field.
4059 If you use an exotic browser, you might want to try it out to
4062 <p>This setting also has no effect on cookies that may have
4063 been stored previously by the browser before starting
4064 <span class="APPLICATION">Privoxy</span>. These would have to
4065 be removed manually.</p>
4067 <p><span class="APPLICATION">Privoxy</span> also uses the
4069 "actions-file.html#FILTER-CONTENT-COOKIES">content-cookies
4070 filter</a> to block some types of cookies. Content cookies are
4071 not effected by <tt class=
4072 "LITERAL">session-cookies-only</tt>.</p>
4075 <dt>Example usage:</dt>
4078 <table class="c4" border="0" width="90%">
4081 <pre class="SCREEN">
4082 +session-cookies-only
4093 <h4 class="SECT3"><a name="SET-IMAGE-BLOCKER" id=
4094 "SET-IMAGE-BLOCKER">8.5.33. set-image-blocker</a></h4>
4096 <div class="VARIABLELIST">
4098 <dt>Typical use:</dt>
4101 <p>Choose the replacement for blocked images</p>
4107 <p>This action alone doesn't do anything noticeable. If
4108 <span class="emphasis EMPHASIS c2">both</span> <tt class=
4109 "LITERAL"><a href="actions-file.html#BLOCK">block</a></tt>
4110 <span class="emphasis EMPHASIS c2">and</span> <tt class=
4112 "actions-file.html#HANDLE-AS-IMAGE">handle-as-image</a></tt>
4113 <span class="emphasis EMPHASIS c2">also</span> apply, i.e. if
4114 the request is to be blocked as an image, <span class=
4115 "emphasis EMPHASIS c2">then</span> the parameter of this action
4116 decides what will be sent as a replacement.</p>
4122 <p>Parameterized.</p>
4130 <p><span class="QUOTE">"pattern"</span> to send a built-in
4131 checkerboard pattern image. The image is visually decent,
4132 scales very well, and makes it obvious where banners were
4137 <p><span class="QUOTE">"blank"</span> to send a built-in
4138 transparent image. This makes banners disappear completely,
4139 but makes it hard to detect where <span class=
4140 "APPLICATION">Privoxy</span> has blocked images on a given
4141 page and complicates troubleshooting if <span class=
4142 "APPLICATION">Privoxy</span> has blocked innocent images,
4143 like navigation icons.</p>
4147 <p><span class="QUOTE">"<tt class=
4148 "REPLACEABLE c5">target-url</tt>"</span> to send a redirect
4149 to <tt class="REPLACEABLE c5">target-url</tt>. You can
4150 redirect to any image anywhere, even in your local
4151 filesystem via <span class="QUOTE">"file:///"</span> URL.
4152 (But note that not all browsers support redirecting to a
4153 local file system).</p>
4155 <p>A good application of redirects is to use special
4156 <span class="APPLICATION">Privoxy</span>-built-in URLs,
4157 which send the built-in images, as <tt class=
4158 "REPLACEABLE c5">target-url</tt>. This has the same visual
4159 effect as specifying <span class="QUOTE">"blank"</span> or
4160 <span class="QUOTE">"pattern"</span> in the first place,
4161 but enables your browser to cache the replacement image,
4162 instead of requesting it over and over again.</p>
4170 <p>The URLs for the built-in images are <span class=
4171 "QUOTE">"http://config.privoxy.org/send-banner?type=<tt class=
4172 "REPLACEABLE c5">type</tt>"</span>, where <tt class=
4173 "REPLACEABLE c5">type</tt> is either <span class=
4174 "QUOTE">"blank"</span> or <span class=
4175 "QUOTE">"pattern"</span>.</p>
4177 <p>There is a third (advanced) type, called <span class=
4178 "QUOTE">"auto"</span>. It is <span class=
4179 "emphasis EMPHASIS c2">NOT</span> to be used in <tt class=
4180 "LITERAL">set-image-blocker</tt>, but meant for use from
4181 <a href="filter-file.html">filters</a>. Auto will select the
4182 type of image that would have applied to the referring page,
4183 had it been an image.</p>
4186 <dt>Example usage:</dt>
4189 <p>Built-in pattern:</p>
4191 <table class="c4" border="0" width="90%">
4194 <pre class="SCREEN">
4195 +set-image-blocker{pattern}
4201 <p>Redirect to the BSD daemon:</p>
4203 <table class="c4" border="0" width="90%">
4206 <pre class="SCREEN">
4207 +set-image-blocker{http://www.freebsd.org/gifs/dae_up3.gif}
4213 <p>Redirect to the built-in pattern for better caching:</p>
4215 <table class="c4" border="0" width="90%">
4218 <pre class="SCREEN">
4219 +set-image-blocker{http://config.privoxy.org/send-banner?type=pattern}
4230 <h3 class="SECT3"><a name="AEN4706" id="AEN4706">8.5.34.
4233 <p>Note that many of these actions have the potential to cause a page
4234 to misbehave, possibly even not to display at all. There are many
4235 ways a site designer may choose to design his site, and what HTTP
4236 header content, and other criteria, he may depend on. There is no way
4237 to have hard and fast rules for all sites. See the <a href=
4238 "appendix.html#ACTIONSANAT">Appendix</a> for a brief example on
4239 troubleshooting actions.</p>
4244 <h2 class="SECT2"><a name="ALIASES" id="ALIASES">8.6. Aliases</a></h2>
4246 <p>Custom <span class="QUOTE">"actions"</span>, known to <span class=
4247 "APPLICATION">Privoxy</span> as <span class="QUOTE">"aliases"</span>,
4248 can be defined by combining other actions. These can in turn be invoked
4249 just like the built-in actions. Currently, an alias name can contain
4250 any character except space, tab, <span class="QUOTE">"="</span>,
4251 <span class="QUOTE">"{"</span> and <span class="QUOTE">"}"</span>, but
4252 we <span class="emphasis EMPHASIS c2">strongly recommend</span> that
4253 you only use <span class="QUOTE">"a"</span> to <span class=
4254 "QUOTE">"z"</span>, <span class="QUOTE">"0"</span> to <span class=
4255 "QUOTE">"9"</span>, <span class="QUOTE">"+"</span>, and <span class=
4256 "QUOTE">"-"</span>. Alias names are not case sensitive, and are not
4257 required to start with a <span class="QUOTE">"+"</span> or <span class=
4258 "QUOTE">"-"</span> sign, since they are merely textually expanded.</p>
4260 <p>Aliases can be used throughout the actions file, but they
4261 <span class="emphasis EMPHASIS c2">must be defined in a special section
4262 at the top of the file!</span> And there can only be one such section
4263 per actions file. Each actions file may have its own alias section, and
4264 the aliases defined in it are only visible within that file.</p>
4266 <p>There are two main reasons to use aliases: One is to save typing for
4267 frequently used combinations of actions, the other one is a gain in
4268 flexibility: If you decide once how you want to handle shops by
4269 defining an alias called <span class="QUOTE">"shop"</span>, you can
4270 later change your policy on shops in <span class=
4271 "emphasis EMPHASIS c2">one</span> place, and your changes will take
4272 effect everywhere in the actions file where the <span class=
4273 "QUOTE">"shop"</span> alias is used. Calling aliases by their purpose
4274 also makes your actions files more readable.</p>
4276 <p>Currently, there is one big drawback to using aliases, though:
4277 <span class="APPLICATION">Privoxy</span>'s built-in web-based action
4278 file editor honors aliases when reading the actions files, but it
4279 expands them before writing. So the effects of your aliases are of
4280 course preserved, but the aliases themselves are lost when you edit
4281 sections that use aliases with it.</p>
4283 <p>Now let's define some aliases...</p>
4285 <table class="c4" border="0" width="100%">
4288 <pre class="SCREEN">
4289 # Useful custom aliases we can use later.
4291 # Note the (required!) section header line and that this section
4292 # must be at the top of the actions file!
4296 # These aliases just save typing later:
4297 # (Note that some already use other aliases!)
4299 +crunch-all-cookies = +<a href=
4300 "actions-file.html#CRUNCH-INCOMING-COOKIES">crunch-incoming-cookies</a> +<a href="actions-file.html#CRUNCH-OUTGOING-COOKIES">crunch-outgoing-cookies</a>
4301 -crunch-all-cookies = -<a href=
4302 "actions-file.html#CRUNCH-INCOMING-COOKIES">crunch-incoming-cookies</a> -<a href="actions-file.html#CRUNCH-OUTGOING-COOKIES">crunch-outgoing-cookies</a>
4303 +block-as-image = +block{Blocked image.} +handle-as-image
4304 allow-all-cookies = -crunch-all-cookies -<a href=
4305 "actions-file.html#SESSION-COOKIES-ONLY">session-cookies-only</a> -<a href=
4306 "actions-file.html#FILTER-CONTENT-COOKIES">filter{content-cookies}</a>
4308 # These aliases define combinations of actions
4309 # that are useful for certain types of sites:
4311 fragile = -<a href="actions-file.html#BLOCK">block</a> -<a href=
4312 "actions-file.html#FILTER">filter</a> -crunch-all-cookies -<a href=
4313 "actions-file.html#FAST-REDIRECTS">fast-redirects</a> -<a href=
4314 "actions-file.html#HIDE-REFERER">hide-referrer</a> -<a href=
4315 "actions-file.html#PREVENT-COMPRESSION">prevent-compression</a>
4317 shop = -crunch-all-cookies -<a href=
4318 "actions-file.html#FILTER-ALL-POPUPS">filter{all-popups}</a>
4320 # Short names for other aliases, for really lazy people ;-)
4322 c0 = +crunch-all-cookies
4323 c1 = -crunch-all-cookies
4329 <p>...and put them to use. These sections would appear in the lower
4330 part of an actions file and define exceptions to the default actions
4331 (as specified further up for the <span class="QUOTE">"/"</span>
4334 <table class="c4" border="0" width="100%">
4337 <pre class="SCREEN">
4338 # These sites are either very complex or very keen on
4339 # user data and require minimal interference to work:
4342 .office.microsoft.com
4343 .windowsupdate.microsoft.com
4344 # Gmail is really mail.google.com, not gmail.com
4348 # Allow cookies (for setting and retrieving your customer data)
4352 .worldpay.com # for quietpc.com
4355 # These shops require pop-ups:
4357 {-filter{all-popups} -filter{unsolicited-popups}}
4365 <p>Aliases like <span class="QUOTE">"shop"</span> and <span class=
4366 "QUOTE">"fragile"</span> are typically used for <span class=
4367 "QUOTE">"problem"</span> sites that require more than one action to be
4368 disabled in order to function properly.</p>
4372 <h2 class="SECT2"><a name="ACT-EXAMPLES" id="ACT-EXAMPLES">8.7. Actions
4373 Files Tutorial</a></h2>
4375 <p>The above chapters have shown <a href="actions-file.html">which
4376 actions files there are and how they are organized</a>, how actions are
4377 <a href="actions-file.html#ACTIONS">specified</a> and <a href=
4378 "actions-file.html#ACTIONS-APPLY">applied to URLs</a>, how <a href=
4379 "actions-file.html#AF-PATTERNS">patterns</a> work, and how to define
4380 and use <a href="actions-file.html#ALIASES">aliases</a>. Now, let's
4381 look at an example <tt class="FILENAME">match-all.action</tt>,
4382 <tt class="FILENAME">default.action</tt> and <tt class=
4383 "FILENAME">user.action</tt> file and see how all these pieces come
4387 <h3 class="SECT3"><a name="AEN4770" id="AEN4770">8.7.1.
4388 match-all.action</a></h3>
4390 <p>Remember <span class="emphasis EMPHASIS c2">all actions are
4391 disabled when matching starts</span>, so we have to explicitly enable
4392 the ones we want.</p>
4394 <p>While the <tt class="FILENAME">match-all.action</tt> file only
4395 contains a single section, it is probably the most important one. It
4396 has only one pattern, <span class="QUOTE">"<tt class=
4397 "LITERAL">/</tt>"</span>, but this pattern <a href=
4398 "actions-file.html#AF-PATTERNS">matches all URLs</a>. Therefore, the
4399 set of actions used in this <span class="QUOTE">"default"</span>
4400 section <span class="emphasis EMPHASIS c2">will be applied to all
4401 requests as a start</span>. It can be partly or wholly overridden by
4402 other actions files like <tt class="FILENAME">default.action</tt> and
4403 <tt class="FILENAME">user.action</tt>, but it will still be largely
4404 responsible for your overall browsing experience.</p>
4406 <p>Again, at the start of matching, all actions are disabled, so
4407 there is no need to disable any actions here. (Remember: a
4408 <span class="QUOTE">"+"</span> preceding the action name enables the
4409 action, a <span class="QUOTE">"-"</span> disables!). Also note how
4410 this long line has been made more readable by splitting it into
4411 multiple lines with line continuation.</p>
4413 <table class="c4" border="0" width="100%">
4416 <pre class="SCREEN">
4419 "actions-file.html#CHANGE-X-FORWARDED-FOR">change-x-forwarded-for{block}</a> \
4420 +<a href="actions-file.html#HIDE-FROM-HEADER">hide-from-header{block}</a> \
4422 "actions-file.html#SET-IMAGE-BLOCKER">set-image-blocker{pattern}</a> \
4431 <p>The default behavior is now set.</p>
4435 <h3 class="SECT3"><a name="AEN4792" id="AEN4792">8.7.2.
4436 default.action</a></h3>
4438 <p>If you aren't a developer, there's no need for you to edit the
4439 <tt class="FILENAME">default.action</tt> file. It is maintained by
4440 the <span class="APPLICATION">Privoxy</span> developers and if you
4441 disagree with some of the sections, you should overrule them in your
4442 <tt class="FILENAME">user.action</tt>.</p>
4444 <p>Understanding the <tt class="FILENAME">default.action</tt> file
4445 can help you with your <tt class="FILENAME">user.action</tt>,
4448 <p>The first section in this file is a special section for internal
4449 use that prevents older <span class="APPLICATION">Privoxy</span>
4450 versions from reading the file:</p>
4452 <table class="c4" border="0" width="100%">
4455 <pre class="SCREEN">
4456 ##########################################################################
4457 # Settings -- Don't change! For internal Privoxy use ONLY.
4458 ##########################################################################
4460 for-privoxy-version=3.0.11
4466 <p>After that comes the (optional) alias section. We'll use the
4467 example section from the above <a href=
4468 "actions-file.html#ALIASES">chapter on aliases</a>, that also
4469 explains why and how aliases are used:</p>
4471 <table class="c4" border="0" width="100%">
4474 <pre class="SCREEN">
4475 ##########################################################################
4477 ##########################################################################
4480 # These aliases just save typing later:
4481 # (Note that some already use other aliases!)
4483 +crunch-all-cookies = +<a href=
4484 "actions-file.html#CRUNCH-INCOMING-COOKIES">crunch-incoming-cookies</a> +<a href="actions-file.html#CRUNCH-OUTGOING-COOKIES">crunch-outgoing-cookies</a>
4485 -crunch-all-cookies = -<a href=
4486 "actions-file.html#CRUNCH-INCOMING-COOKIES">crunch-incoming-cookies</a> -<a href="actions-file.html#CRUNCH-OUTGOING-COOKIES">crunch-outgoing-cookies</a>
4487 +block-as-image = +block{Blocked image.} +handle-as-image
4488 mercy-for-cookies = -crunch-all-cookies -<a href=
4489 "actions-file.html#SESSION-COOKIES-ONLY">session-cookies-only</a> -<a href=
4490 "actions-file.html#FILTER-CONTENT-COOKIES">filter{content-cookies}</a>
4492 # These aliases define combinations of actions
4493 # that are useful for certain types of sites:
4495 fragile = -<a href="actions-file.html#BLOCK">block</a> -<a href=
4496 "actions-file.html#FILTER">filter</a> -crunch-all-cookies -<a href=
4497 "actions-file.html#FAST-REDIRECTS">fast-redirects</a> -<a href=
4498 "actions-file.html#HIDE-REFERER">hide-referrer</a>
4499 shop = -crunch-all-cookies -<a href=
4500 "actions-file.html#FILTER-ALL-POPUPS">filter{all-popups}</a>
4506 <p>The first of our specialized sections is concerned with
4507 <span class="QUOTE">"fragile"</span> sites, i.e. sites that require
4508 minimum interference, because they are either very complex or very
4509 keen on tracking you (and have mechanisms in place that make them
4510 unusable for people who avoid being tracked). We will simply use our
4511 pre-defined <tt class="LITERAL">fragile</tt> alias instead of stating
4512 the list of actions explicitly:</p>
4514 <table class="c4" border="0" width="100%">
4517 <pre class="SCREEN">
4518 ##########################################################################
4519 # Exceptions for sites that'll break under the default action set:
4520 ##########################################################################
4522 # "Fragile" Use a minimum set of actions for these sites (see alias above):
4525 .office.microsoft.com # surprise, surprise!
4526 .windowsupdate.microsoft.com
4533 <p>Shopping sites are not as fragile, but they typically require
4534 cookies to log in, and pop-up windows for shopping carts or item
4535 details. Again, we'll use a pre-defined alias:</p>
4537 <table class="c4" border="0" width="100%">
4540 <pre class="SCREEN">
4545 .worldpay.com # for quietpc.com
4553 <p>The <tt class="LITERAL"><a href=
4554 "actions-file.html#FAST-REDIRECTS">fast-redirects</a></tt> action,
4555 which may have been enabled in <tt class=
4556 "FILENAME">match-all.action</tt>, breaks some sites. So disable it
4557 for popular sites where we know it misbehaves:</p>
4559 <table class="c4" border="0" width="100%">
4562 <pre class="SCREEN">
4563 { -<a href="actions-file.html#FAST-REDIRECTS">fast-redirects</a> }
4567 .altavista.com/.*(like|url|link):http
4568 .altavista.com/trans.*urltext=http
4575 <p>It is important that <span class="APPLICATION">Privoxy</span>
4576 knows which URLs belong to images, so that <span class=
4577 "emphasis EMPHASIS c2">if</span> they are to be blocked, a substitute
4578 image can be sent, rather than an HTML page. Contacting the remote
4579 site to find out is not an option, since it would destroy the loading
4580 time advantage of banner blocking, and it would feed the advertisers
4581 information about you. We can mark any URL as an image with the
4582 <tt class="LITERAL"><a href=
4583 "actions-file.html#HANDLE-AS-IMAGE">handle-as-image</a></tt> action,
4584 and marking all URLs that end in a known image file extension is a
4587 <table class="c4" border="0" width="100%">
4590 <pre class="SCREEN">
4591 ##########################################################################
4593 ##########################################################################
4595 # Define which file types will be treated as images, in case they get
4596 # blocked further down this file:
4598 { +<a href="actions-file.html#HANDLE-AS-IMAGE">handle-as-image</a> }
4599 /.*\.(gif|jpe?g|png|bmp|ico)$
4605 <p>And then there are known banner sources. They often use scripts to
4606 generate the banners, so it won't be visible from the URL that the
4607 request is for an image. Hence we block them <span class=
4608 "emphasis EMPHASIS c2">and</span> mark them as images in one go, with
4609 the help of our <tt class="LITERAL">+block-as-image</tt> alias
4610 defined above. (We could of course just as well use <tt class=
4611 "LITERAL">+<a href="actions-file.html#BLOCK">block</a> +<a href=
4612 "actions-file.html#HANDLE-AS-IMAGE">handle-as-image</a></tt> here.)
4613 Remember that the type of the replacement image is chosen by the
4614 <tt class="LITERAL"><a href=
4615 "actions-file.html#SET-IMAGE-BLOCKER">set-image-blocker</a></tt>
4616 action. Since all URLs have matched the default section with its
4617 <tt class="LITERAL">+<a href=
4618 "actions-file.html#SET-IMAGE-BLOCKER">set-image-blocker</a>{pattern}</tt>
4619 action before, it still applies and needn't be repeated:</p>
4621 <table class="c4" border="0" width="100%">
4624 <pre class="SCREEN">
4625 # Known ad generators:
4630 .ad.*.doubleclick.net
4631 .a.yimg.com/(?:(?!/i/).)*$
4632 .a[0-9].yimg.com/(?:(?!/i/).)*$
4640 <p>One of the most important jobs of <span class=
4641 "APPLICATION">Privoxy</span> is to block banners. Many of these can
4642 be <span class="QUOTE">"blocked"</span> by the <tt class=
4644 "actions-file.html#FILTER">filter</a>{banners-by-size}</tt> action,
4645 which we enabled above, and which deletes the references to banner
4646 images from the pages while they are loaded, so the browser doesn't
4647 request them anymore, and hence they don't need to be blocked here.
4648 But this naturally doesn't catch all banners, and some people choose
4649 not to use filters, so we need a comprehensive list of patterns for
4650 banner URLs here, and apply the <tt class="LITERAL"><a href=
4651 "actions-file.html#BLOCK">block</a></tt> action to them.</p>
4653 <p>First comes many generic patterns, which do most of the work, by
4654 matching typical domain and path name components of banners. Then
4655 comes a list of individual patterns for specific sites, which is
4656 omitted here to keep the example short:</p>
4658 <table class="c4" border="0" width="100%">
4661 <pre class="SCREEN">
4662 ##########################################################################
4663 # Block these fine banners:
4664 ##########################################################################
4665 { <a href="actions-file.html#BLOCK">+block{Banner ads.}</a> }
4673 /.*count(er)?\.(pl|cgi|exe|dll|asp|php[34]?)
4674 /(?:.*/)?(publicite|werbung|rekla(ma|me|am)|annonse|maino(kset|nta|s)?)/
4676 # Site-specific patterns (abbreviated):
4684 <p>It's quite remarkable how many advertisers actually call their
4685 banner servers ads.<tt class="REPLACEABLE c5">company</tt>.com, or
4686 call the directory in which the banners are stored simply
4687 <span class="QUOTE">"banners"</span>. So the above generic patterns
4688 are surprisingly effective.</p>
4690 <p>But being very generic, they necessarily also catch URLs that we
4691 don't want to block. The pattern <tt class="LITERAL">.*ads.</tt> e.g.
4692 catches <span class="QUOTE">"nasty-<span class=
4693 "emphasis EMPHASIS c2">ads</span>.nasty-corp.com"</span> as intended,
4694 but also <span class="QUOTE">"downlo<span class=
4695 "emphasis EMPHASIS c2">ads</span>.sourcefroge.net"</span> or
4696 <span class="QUOTE">"<span class=
4697 "emphasis EMPHASIS c2">ads</span>l.some-provider.net."</span> So here
4698 come some well-known exceptions to the <tt class="LITERAL">+<a href=
4699 "actions-file.html#BLOCK">block</a></tt> section above.</p>
4701 <p>Note that these are exceptions to exceptions from the default!
4702 Consider the URL <span class=
4703 "QUOTE">"downloads.sourcefroge.net"</span>: Initially, all actions
4704 are deactivated, so it wouldn't get blocked. Then comes the defaults
4705 section, which matches the URL, but just deactivates the <tt class=
4706 "LITERAL"><a href="actions-file.html#BLOCK">block</a></tt> action
4707 once again. Then it matches <tt class="LITERAL">.*ads.</tt>, an
4708 exception to the general non-blocking policy, and suddenly <tt class=
4709 "LITERAL"><a href="actions-file.html#BLOCK">+block</a></tt> applies.
4710 And now, it'll match <tt class="LITERAL">.*loads.</tt>, where
4711 <tt class="LITERAL"><a href="actions-file.html#BLOCK">-block</a></tt>
4712 applies, so (unless it matches <span class=
4713 "emphasis EMPHASIS c2">again</span> further down) it ends up with no
4714 <tt class="LITERAL"><a href="actions-file.html#BLOCK">block</a></tt>
4715 action applying.</p>
4717 <table class="c4" border="0" width="100%">
4720 <pre class="SCREEN">
4721 ##########################################################################
4722 # Save some innocent victims of the above generic block patterns:
4723 ##########################################################################
4727 { -<a href="actions-file.html#BLOCK">block</a> }
4728 adv[io]*. # (for advogato.org and advice.*)
4729 adsl. # (has nothing to do with ads)
4730 adobe. # (has nothing to do with ads either)
4731 ad[ud]*. # (adult.* and add.*)
4732 .edu # (universities don't host banners (yet!))
4733 .*loads. # (downloads, uploads etc)
4741 www.globalintersec.com/adv # (adv = advanced)
4742 www.ugu.com/sui/ugu/adv
4748 <p>Filtering source code can have nasty side effects, so make an
4749 exception for our friends at sourceforge.net, and all paths with
4750 <span class="QUOTE">"cvs"</span> in them. Note that <tt class=
4751 "LITERAL">-<a href="actions-file.html#FILTER">filter</a></tt>
4752 disables <span class="emphasis EMPHASIS c2">all</span> filters in one
4755 <table class="c4" border="0" width="100%">
4758 <pre class="SCREEN">
4759 # Don't filter code!
4761 { -<a href="actions-file.html#FILTER">filter</a> }
4772 <p>The actual <tt class="FILENAME">default.action</tt> is of course
4773 much more comprehensive, but we hope this example made clear how it
4778 <h3 class="SECT3"><a name="AEN4905" id="AEN4905">8.7.3.
4779 user.action</a></h3>
4781 <p>So far we are painting with a broad brush by setting general
4782 policies, which would be a reasonable starting point for many people.
4783 Now, you might want to be more specific and have customized rules
4784 that are more suitable to your personal habits and preferences. These
4785 would be for narrowly defined situations like your ISP or your bank,
4786 and should be placed in <tt class="FILENAME">user.action</tt>, which
4787 is parsed after all other actions files and hence has the last word,
4788 over-riding any previously defined actions. <tt class=
4789 "FILENAME">user.action</tt> is also a <span class=
4790 "emphasis EMPHASIS c2">safe</span> place for your personal settings,
4791 since <tt class="FILENAME">default.action</tt> is actively maintained
4792 by the <span class="APPLICATION">Privoxy</span> developers and you'll
4793 probably want to install updated versions from time to time.</p>
4795 <p>So let's look at a few examples of things that one might typically
4796 do in <tt class="FILENAME">user.action</tt>:</p>
4798 <table class="c4" border="0" width="100%">
4801 <pre class="SCREEN">
4802 # My user.action file. <fred@example.com>
4808 <p>As <a href="actions-file.html#ALIASES">aliases</a> are local to
4809 the actions file that they are defined in, you can't use the ones
4810 from <tt class="FILENAME">default.action</tt>, unless you repeat them
4813 <table class="c4" border="0" width="100%">
4816 <pre class="SCREEN">
4817 # Aliases are local to the file they are defined in.
4818 # (Re-)define aliases for this file:
4822 # These aliases just save typing later, and the alias names should
4823 # be self explanatory.
4825 +crunch-all-cookies = +crunch-incoming-cookies +crunch-outgoing-cookies
4826 -crunch-all-cookies = -crunch-incoming-cookies -crunch-outgoing-cookies
4827 allow-all-cookies = -crunch-all-cookies -session-cookies-only
4828 allow-popups = -filter{all-popups}
4829 +block-as-image = +block{Blocked as image.} +handle-as-image
4830 -block-as-image = -block
4832 # These aliases define combinations of actions that are useful for
4833 # certain types of sites:
4835 fragile = -block -crunch-all-cookies -filter -fast-redirects -hide-referrer
4836 shop = -crunch-all-cookies allow-popups
4838 # Allow ads for selected useful free sites:
4840 allow-ads = -block -filter{banners-by-size} -filter{banners-by-link}
4842 # Alias for specific file types that are text, but might have conflicting
4843 # MIME types. We want the browser to force these to be text documents.
4844 handle-as-text = -<a href="actions-file.html#FILTER">filter</a> +-<a href=
4845 "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>
4851 <p>Say you have accounts on some sites that you visit regularly, and
4852 you don't want to have to log in manually each time. So you'd like to
4853 allow persistent cookies for these sites. The <tt class=
4854 "LITERAL">allow-all-cookies</tt> alias defined above does exactly
4855 that, i.e. it disables crunching of cookies in any direction, and the
4856 processing of cookies to make them only temporary.</p>
4858 <table class="c4" border="0" width="100%">
4861 <pre class="SCREEN">
4862 { allow-all-cookies }
4872 <p>Your bank is allergic to some filter, but you don't know which, so
4873 you disable them all:</p>
4875 <table class="c4" border="0" width="100%">
4878 <pre class="SCREEN">
4879 { -<a href="actions-file.html#FILTER">filter</a> }
4880 .your-home-banking-site.com
4886 <p>Some file types you may not want to filter for various
4889 <table class="c4" border="0" width="100%">
4892 <pre class="SCREEN">
4893 # Technical documentation is likely to contain strings that might
4894 # erroneously get altered by the JavaScript-oriented filters:
4899 # And this stupid host sends streaming video with a wrong MIME type,
4900 # so that Privoxy thinks it is getting HTML and starts filtering:
4902 stupid-server.example.com/
4908 <p>Example of a simple <a href="actions-file.html#BLOCK">block</a>
4909 action. Say you've seen an ad on your favourite page on example.com
4910 that you want to get rid of. You have right-clicked the image,
4911 selected <span class="QUOTE">"copy image location"</span> and pasted
4912 the URL below while removing the leading http://, into a <tt class=
4913 "LITERAL">{ +block{} }</tt> section. Note that <tt class="LITERAL">{
4914 +handle-as-image }</tt> need not be specified, since all URLs ending
4915 in <tt class="LITERAL">.gif</tt> will be tagged as images by the
4916 general rules as set in default.action anyway:</p>
4918 <table class="c4" border="0" width="100%">
4921 <pre class="SCREEN">
4922 { +<a href="actions-file.html#BLOCK">block</a>{Nasty ads.} }
4923 www.example.com/nasty-ads/sponsor\.gif
4924 another.example.net/more/junk/here/
4930 <p>The URLs of dynamically generated banners, especially from large
4931 banner farms, often don't use the well-known image file name
4932 extensions, which makes it impossible for <span class=
4933 "APPLICATION">Privoxy</span> to guess the file type just by looking
4934 at the URL. You can use the <tt class="LITERAL">+block-as-image</tt>
4935 alias defined above for these cases. Note that objects which match
4936 this rule but then turn out NOT to be an image are typically rendered
4937 as a <span class="QUOTE">"broken image"</span> icon by the browser.
4940 <table class="c4" border="0" width="100%">
4943 <pre class="SCREEN">
4954 <p>Now you noticed that the default configuration breaks Forbes
4955 Magazine, but you were too lazy to find out which action is the
4956 culprit, and you were again too lazy to give <a href=
4957 "contact.html">feedback</a>, so you just used the <tt class=
4958 "LITERAL">fragile</tt> alias on the site, and -- <span class=
4959 "emphasis EMPHASIS c2">whoa!</span> -- it worked. The <tt class=
4960 "LITERAL">fragile</tt> aliases disables those actions that are most
4961 likely to break a site. Also, good for testing purposes to see if it
4962 is <span class="APPLICATION">Privoxy</span> that is causing the
4963 problem or not. We later find other regular sites that misbehave, and
4964 add those to our personalized list of troublemakers:</p>
4966 <table class="c4" border="0" width="100%">
4969 <pre class="SCREEN">
4979 <p>You like the <span class="QUOTE">"fun"</span> text replacements in
4980 <tt class="FILENAME">default.filter</tt>, but it is disabled in the
4981 distributed actions file. So you'd like to turn it on in your
4982 private, update-safe config, once and for all:</p>
4984 <table class="c4" border="0" width="100%">
4987 <pre class="SCREEN">
4988 { +<a href="actions-file.html#FILTER-FUN">filter{fun}</a> }
4995 <p>Note that the above is not really a good idea: There are
4996 exceptions to the filters in <tt class="FILENAME">default.action</tt>
4997 for things that really shouldn't be filtered, like code on
4998 CVS->Web interfaces. Since <tt class="FILENAME">user.action</tt>
4999 has the last word, these exceptions won't be valid for the
5000 <span class="QUOTE">"fun"</span> filtering specified here.</p>
5002 <p>You might also worry about how your favourite free websites are
5003 funded, and find that they rely on displaying banner advertisements
5004 to survive. So you might want to specifically allow banners for those
5005 sites that you feel provide value to you:</p>
5007 <table class="c4" border="0" width="100%">
5010 <pre class="SCREEN">
5020 <p>Note that <tt class="LITERAL">allow-ads</tt> has been aliased to
5021 <tt class="LITERAL">-<a href=
5022 "actions-file.html#BLOCK">block</a></tt>, <tt class=
5024 "actions-file.html#FILTER-BANNERS-BY-SIZE">filter{banners-by-size}</a></tt>,
5025 and <tt class="LITERAL">-<a href=
5026 "actions-file.html#FILTER-BANNERS-BY-LINK">filter{banners-by-link}</a></tt>
5029 <p>Invoke another alias here to force an over-ride of the MIME type
5030 <tt class="LITERAL">application/x-sh</tt> which typically would open
5031 a download type dialog. In my case, I want to look at the shell
5032 script, and then I can save it should I choose to.</p>
5034 <table class="c4" border="0" width="100%">
5037 <pre class="SCREEN">
5045 <p><tt class="FILENAME">user.action</tt> is generally the best place
5046 to define exceptions and additions to the default policies of
5047 <tt class="FILENAME">default.action</tt>. Some actions are safe to
5048 have their default policies set here though. So let's set a default
5049 policy to have a <span class="QUOTE">"blank"</span> image as opposed
5050 to the checkerboard pattern for <span class=
5051 "emphasis EMPHASIS c2">ALL</span> sites. <span class=
5052 "QUOTE">"/"</span> of course matches all URL paths and patterns:</p>
5054 <table class="c4" border="0" width="100%">
5057 <pre class="SCREEN">
5059 "actions-file.html#SET-IMAGE-BLOCKER">set-image-blocker{blank}</a> }
5069 <div class="NAVFOOTER">
5070 <hr class="c1" width="100%">
5072 <table summary="Footer navigation table" width="100%" border="0"
5073 cellpadding="0" cellspacing="0">
5075 <td width="33%" align="left" valign="top"><a href="config.html"
5076 accesskey="P">Prev</a></td>
5078 <td width="34%" align="center" valign="top"><a href="index.html"
5079 accesskey="H">Home</a></td>
5081 <td width="33%" align="right" valign="top"><a href="filter-file.html"
5082 accesskey="N">Next</a></td>
5086 <td width="33%" align="left" valign="top">The Main Configuration
5089 <td width="34%" align="center" valign="top"> </td>
5091 <td width="33%" align="right" valign="top">Filter Files</td>