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41 <h1 class="SECT1"><a name="ACTIONS-FILE" id="ACTIONS-FILE">8. Actions
44 <p>The actions files are used to define what <span class=
45 "emphasis"><i class="EMPHASIS">actions</i></span> <span class=
46 "APPLICATION">Privoxy</span> takes for which URLs, and thus determines
47 how ad images, cookies and various other aspects of HTTP content and
48 transactions are handled, and on which sites (or even parts thereof).
49 There are a number of such actions, with a wide range of functionality.
50 Each action does something a little different. These actions give us a
51 veritable arsenal of tools with which to exert our control, preferences
52 and independence. Actions can be combined so that their effects are
53 aggregated when applied against a given set of URLs.</p>
55 <p>There are three action files included with <span class=
56 "APPLICATION">Privoxy</span> with differing purposes:</p>
60 <p><tt class="FILENAME">match-all.action</tt> - is used to define
61 which <span class="QUOTE">"actions"</span> relating to
62 banner-blocking, images, pop-ups, content modification, cookie
63 handling etc should be applied by default. It should be the first
64 actions file loaded</p>
68 <p><tt class="FILENAME">default.action</tt> - defines many exceptions
69 (both positive and negative) from the default set of actions that's
70 configured in <tt class="FILENAME">match-all.action</tt>. It is a set
71 of rules that should work reasonably well as-is for most users. This
72 file is only supposed to be edited by the developers. It should be
73 the second actions file loaded.</p>
77 <p><tt class="FILENAME">user.action</tt> - is intended to be for
78 local site preferences and exceptions. As an example, if your ISP or
79 your bank has specific requirements, and need special handling, this
80 kind of thing should go here. This file will not be upgraded.</p>
84 <p><span class="GUIBUTTON">Edit</span> <span class="GUIBUTTON">Set to
85 Cautious</span> <span class="GUIBUTTON">Set to Medium</span>
86 <span class="GUIBUTTON">Set to Advanced</span></p>
88 <p>These have increasing levels of aggressiveness <span class=
89 "emphasis"><i class="EMPHASIS">and have no influence on your browsing
90 unless you select them explicitly in the editor</i></span>. A default
91 installation should be pre-set to <tt class="LITERAL">Cautious</tt>.
92 New users should try this for a while before adjusting the settings
93 to more aggressive levels. The more aggressive the settings, then the
94 more likelihood there is of problems such as sites not working as
97 <p>The <span class="GUIBUTTON">Edit</span> button allows you to turn
98 each action on/off individually for fine-tuning. The <span class=
99 "GUIBUTTON">Cautious</span> button changes the actions list to
100 low/safe settings which will activate ad blocking and a minimal set
101 of <span class="APPLICATION">Privoxy</span>'s features, and
102 subsequently there will be less of a chance for accidental problems.
103 The <span class="GUIBUTTON">Medium</span> button sets the list to a
104 medium level of other features and a low level set of privacy
105 features. The <span class="GUIBUTTON">Advanced</span> button sets the
106 list to a high level of ad blocking and medium level of privacy. See
107 the chart below. The latter three buttons over-ride any changes via
108 with the <span class="GUIBUTTON">Edit</span> button. More fine-tuning
109 can be done in the lower sections of this internal page.</p>
111 <p>While the actions file editor allows to enable these settings in
112 all actions files, they are only supposed to be enabled in the first
113 one to make sure you don't unintentionally overrule earlier
116 <p>The default profiles, and their associated actions, as pre-defined
117 in <tt class="FILENAME">default.action</tt> are:</p>
120 <a name="AEN2682" id="AEN2682"></a>
122 <p><b>Table 1. Default Configurations</b></p>
124 <table border="1" frame="border" rules="all" class="CALSTABLE">
125 <col width="1*" title="C1">
126 <col width="1*" title="C2">
127 <col width="1*" title="C3">
128 <col width="1*" title="C4">
144 <td>Ad-blocking Aggressiveness</td>
154 <td>Ad-filtering by size</td>
164 <td>Ad-filtering by link</td>
174 <td>Pop-up killing</td>
184 <td>Privacy Features</td>
194 <td>Cookie handling</td>
198 <td>session-only</td>
204 <td>Referer forging</td>
214 <td>GIF de-animation</td>
224 <td>Fast redirects</td>
244 <td>JavaScript taming</td>
254 <td>Web-bug killing</td>
264 <td>Image tag reordering</td>
278 <p>The list of actions files to be used are defined in the main
279 configuration file, and are processed in the order they are defined (e.g.
280 <tt class="FILENAME">default.action</tt> is typically processed before
281 <tt class="FILENAME">user.action</tt>). The content of these can all be
282 viewed and edited from <a href="http://config.privoxy.org/show-status"
283 target="_top">http://config.privoxy.org/show-status</a>. The over-riding
284 principle when applying actions, is that the last action that matches a
285 given URL wins. The broadest, most general rules go first (defined in
286 <tt class="FILENAME">default.action</tt>), followed by any exceptions
287 (typically also in <tt class="FILENAME">default.action</tt>), which are
288 then followed lastly by any local preferences (typically in <span class=
289 "emphasis"><i class="EMPHASIS">user</i></span><tt class=
290 "FILENAME">.action</tt>). Generally, <tt class=
291 "FILENAME">user.action</tt> has the last word.</p>
293 <p>An actions file typically has multiple sections. If you want to use
294 <span class="QUOTE">"aliases"</span> in an actions file, you have to
295 place the (optional) <a href="actions-file.html#ALIASES">alias
296 section</a> at the top of that file. Then comes the default set of rules
297 which will apply universally to all sites and pages (be <span class=
298 "emphasis"><i class="EMPHASIS">very careful</i></span> with using such a
299 universal set in <tt class="FILENAME">user.action</tt> or any other
300 actions file after <tt class="FILENAME">default.action</tt>, because it
301 will override the result from consulting any previous file). And then
302 below that, exceptions to the defined universal policies. You can regard
303 <tt class="FILENAME">user.action</tt> as an appendix to <tt class=
304 "FILENAME">default.action</tt>, with the advantage that it is a separate
305 file, which makes preserving your personal settings across <span class=
306 "APPLICATION">Privoxy</span> upgrades easier.</p>
308 <p>Actions can be used to block anything you want, including ads,
309 banners, or just some obnoxious URL whose content you would rather not
310 see. Cookies can be accepted or rejected, or accepted only during the
311 current browser session (i.e. not written to disk), content can be
312 modified, some JavaScripts tamed, user-tracking fooled, and much more.
313 See below for a <a href="actions-file.html#ACTIONS">complete list of
317 <h2 class="SECT2"><a name="RIGHT-MIX" id="RIGHT-MIX">8.1. Finding the
320 <p>Note that some <a href="actions-file.html#ACTIONS">actions</a>, like
321 cookie suppression or script disabling, may render some sites unusable
322 that rely on these techniques to work properly. Finding the right mix
323 of actions is not always easy and certainly a matter of personal taste.
324 And, things can always change, requiring refinements in the
325 configuration. In general, it can be said that the more <span class=
326 "QUOTE">"aggressive"</span> your default settings (in the top section
327 of the actions file) are, the more exceptions for <span class=
328 "QUOTE">"trusted"</span> sites you will have to make later. If, for
329 example, you want to crunch all cookies per default, you'll have to
330 make exceptions from that rule for sites that you regularly use and
331 that require cookies for actually useful purposes, like maybe your
332 bank, favorite shop, or newspaper.</p>
334 <p>We have tried to provide you with reasonable rules to start from in
335 the distribution actions files. But there is no general rule of thumb
336 on these things. There just are too many variables, and sites are
337 constantly changing. Sooner or later you will want to change the rules
338 (and read this chapter again :).</p>
342 <h2 class="SECT2"><a name="HOW-TO-EDIT" id="HOW-TO-EDIT">8.2. How to
345 <p>The easiest way to edit the actions files is with a browser by using
346 our browser-based editor, which can be reached from <a href=
347 "http://config.privoxy.org/show-status" target=
348 "_top">http://config.privoxy.org/show-status</a>. Note: the config file
350 "config.html#ENABLE-EDIT-ACTIONS">enable-edit-actions</a> must be
351 enabled for this to work. The editor allows both fine-grained control
352 over every single feature on a per-URL basis, and easy choosing from
353 wholesale sets of defaults like <span class="QUOTE">"Cautious"</span>,
354 <span class="QUOTE">"Medium"</span> or <span class=
355 "QUOTE">"Advanced"</span>. Warning: the <span class=
356 "QUOTE">"Advanced"</span> setting is more aggressive, and will be more
357 likely to cause problems for some sites. Experienced users only!</p>
359 <p>If you prefer plain text editing to GUIs, you can of course also
360 directly edit the the actions files with your favorite text editor.
361 Look at <tt class="FILENAME">default.action</tt> which is richly
362 commented with many good examples.</p>
366 <h2 class="SECT2"><a name="ACTIONS-APPLY" id="ACTIONS-APPLY">8.3. How
367 Actions are Applied to Requests</a></h2>
369 <p>Actions files are divided into sections. There are special sections,
370 like the <span class="QUOTE">"<a href=
371 "actions-file.html#ALIASES">alias</a>"</span> sections which will be
372 discussed later. For now let's concentrate on regular sections: They
373 have a heading line (often split up to multiple lines for readability)
374 which consist of a list of actions, separated by whitespace and
375 enclosed in curly braces. Below that, there is a list of URL and tag
376 patterns, each on a separate line.</p>
378 <p>To determine which actions apply to a request, the URL of the
379 request is compared to all URL patterns in each <span class=
380 "QUOTE">"action file"</span>. Every time it matches, the list of
381 applicable actions for the request is incrementally updated, using the
382 heading of the section in which the pattern is located. The same is
383 done again for tags and tag patterns later on.</p>
385 <p>If multiple applying sections set the same action differently, the
386 last match wins. If not, the effects are aggregated. E.g. a URL might
387 match a regular section with a heading line of <tt class="LITERAL">{
388 +<a href="actions-file.html#HANDLE-AS-IMAGE">handle-as-image</a>
389 }</tt>, then later another one with just <tt class="LITERAL">{
390 +<a href="actions-file.html#BLOCK">block</a> }</tt>, resulting in
391 <span class="emphasis"><i class="EMPHASIS">both</i></span> actions to
392 apply. And there may well be cases where you will want to combine
393 actions together. Such a section then might look like:</p>
395 <table border="0" bgcolor="#E0E0E0" width="100%">
399 { +<tt class="LITERAL">handle-as-image</tt> +<tt class=
400 "LITERAL">block{Banner ads.}</tt> }
401 # Block these as if they were images. Send no block page.
403 media.example.com/.*banners
404 .example.com/images/ads/
410 <p>You can trace this process for URL patterns and any given URL by
411 visiting <a href="http://config.privoxy.org/show-url-info" target=
412 "_top">http://config.privoxy.org/show-url-info</a>.</p>
414 <p>Examples and more detail on this is provided in the Appendix,
415 <a href="appendix.html#ACTIONSANAT">Troubleshooting: Anatomy of an
416 Action</a> section.</p>
420 <h2 class="SECT2"><a name="AF-PATTERNS" id="AF-PATTERNS">8.4.
423 <p>As mentioned, <span class="APPLICATION">Privoxy</span> uses
424 <span class="QUOTE">"patterns"</span> to determine what <span class=
425 "emphasis"><i class="EMPHASIS">actions</i></span> might apply to which
426 sites and pages your browser attempts to access. These <span class=
427 "QUOTE">"patterns"</span> use wild card type <span class=
428 "emphasis"><i class="EMPHASIS">pattern</i></span> matching to achieve a
429 high degree of flexibility. This allows one expression to be expanded
430 and potentially match against many similar patterns.</p>
432 <p>Generally, an URL pattern has the form <tt class=
433 "LITERAL"><host><port>/<path></tt>, where the
434 <tt class="LITERAL"><host></tt>, the <tt class=
435 "LITERAL"><port></tt> and the <tt class=
436 "LITERAL"><path></tt> are optional. (This is why the special
437 <tt class="LITERAL">/</tt> pattern matches all URLs). Note that the
438 protocol portion of the URL pattern (e.g. <tt class=
439 "LITERAL">http://</tt>) should <span class="emphasis"><i class=
440 "EMPHASIS">not</i></span> be included in the pattern. This is assumed
443 <p>The pattern matching syntax is different for the host and path parts
444 of the URL. The host part uses a simple globbing type matching
445 technique, while the path part uses more flexible <a href=
446 "http://en.wikipedia.org/wiki/Regular_expressions" target=
447 "_top"><span class="QUOTE">"Regular Expressions"</span></a> (POSIX
450 <p>The port part of a pattern is a decimal port number preceded by a
451 colon (<tt class="LITERAL">:</tt>). If the host part contains a
452 numerical IPv6 address, it has to be put into angle brackets
453 (<tt class="LITERAL"><</tt>, <tt class="LITERAL">></tt>).</p>
455 <div class="VARIABLELIST">
457 <dt><tt class="LITERAL">www.example.com/</tt></dt>
460 <p>is a host-only pattern and will match any request to
461 <tt class="LITERAL">www.example.com</tt>, regardless of which
462 document on that server is requested. So ALL pages in this domain
463 would be covered by the scope of this action. Note that a simple
464 <tt class="LITERAL">example.com</tt> is different and would NOT
468 <dt><tt class="LITERAL">www.example.com</tt></dt>
471 <p>means exactly the same. For host-only patterns, the trailing
472 <tt class="LITERAL">/</tt> may be omitted.</p>
475 <dt><tt class="LITERAL">www.example.com/index.html</tt></dt>
478 <p>matches all the documents on <tt class=
479 "LITERAL">www.example.com</tt> whose name starts with <tt class=
480 "LITERAL">/index.html</tt>.</p>
483 <dt><tt class="LITERAL">www.example.com/index.html$</tt></dt>
486 <p>matches only the single document <tt class=
487 "LITERAL">/index.html</tt> on <tt class=
488 "LITERAL">www.example.com</tt>.</p>
491 <dt><tt class="LITERAL">/index.html$</tt></dt>
494 <p>matches the document <tt class="LITERAL">/index.html</tt>,
495 regardless of the domain, i.e. on <span class=
496 "emphasis"><i class="EMPHASIS">any</i></span> web server
500 <dt><tt class="LITERAL">/</tt></dt>
503 <p>Matches any URL because there's no requirement for either the
504 domain or the path to match anything.</p>
507 <dt><tt class="LITERAL">:8000/</tt></dt>
510 <p>Matches any URL pointing to TCP port 8000.</p>
513 <dt><tt class="LITERAL">10.0.0.1/</tt></dt>
516 <p>Matches any URL with the host address <tt class=
517 "LITERAL">10.0.0.1</tt>. (Note that the real URL uses plain
518 brackets, not angle brackets.)</p>
521 <dt><tt class="LITERAL"><2001:db8::1>/</tt></dt>
524 <p>Matches any URL with the host address <tt class=
525 "LITERAL">2001:db8::1</tt>. (Note that the real URL uses plain
526 brackets, not angle brackets.)</p>
529 <dt><tt class="LITERAL">index.html</tt></dt>
532 <p>matches nothing, since it would be interpreted as a domain
533 name and there is no top-level domain called <tt class=
534 "LITERAL">.html</tt>. So its a mistake.</p>
540 <h3 class="SECT3"><a name="HOST-PATTERN" id="HOST-PATTERN">8.4.1. The
541 Host Pattern</a></h3>
543 <p>The matching of the host part offers some flexible options: if the
544 host pattern starts or ends with a dot, it becomes unanchored at that
545 end. The host pattern is often referred to as domain pattern as it is
546 usually used to match domain names and not IP addresses. For
549 <div class="VARIABLELIST">
551 <dt><tt class="LITERAL">.example.com</tt></dt>
554 <p>matches any domain with first-level domain <tt class=
555 "LITERAL">com</tt> and second-level domain <tt class=
556 "LITERAL">example</tt>. For example <tt class=
557 "LITERAL">www.example.com</tt>, <tt class=
558 "LITERAL">example.com</tt> and <tt class=
559 "LITERAL">foo.bar.baz.example.com</tt>. Note that it wouldn't
560 match if the second-level domain was <tt class=
561 "LITERAL">another-example</tt>.</p>
564 <dt><tt class="LITERAL">www.</tt></dt>
567 <p>matches any domain that <span class="emphasis"><i class=
568 "EMPHASIS">STARTS</i></span> with <tt class="LITERAL">www.</tt>
569 (It also matches the domain <tt class="LITERAL">www</tt> but
570 most of the time that doesn't matter.)</p>
573 <dt><tt class="LITERAL">.example.</tt></dt>
576 <p>matches any domain that <span class="emphasis"><i class=
577 "EMPHASIS">CONTAINS</i></span> <tt class=
578 "LITERAL">.example.</tt>. And, by the way, also included would
579 be any files or documents that exist within that domain since
580 no path limitations are specified. (Correctly speaking: It
581 matches any FQDN that contains <tt class="LITERAL">example</tt>
582 as a domain.) This might be <tt class=
583 "LITERAL">www.example.com</tt>, <tt class=
584 "LITERAL">news.example.de</tt>, or <tt class=
585 "LITERAL">www.example.net/cgi/testing.pl</tt> for instance. All
586 these cases are matched.</p>
591 <p>Additionally, there are wild-cards that you can use in the domain
592 names themselves. These work similarly to shell globbing type
593 wild-cards: <span class="QUOTE">"*"</span> represents zero or more
594 arbitrary characters (this is equivalent to the <a href=
595 "http://en.wikipedia.org/wiki/Regular_expressions" target=
596 "_top"><span class="QUOTE">"Regular Expression"</span></a> based
597 syntax of <span class="QUOTE">".*"</span>), <span class=
598 "QUOTE">"?"</span> represents any single character (this is
599 equivalent to the regular expression syntax of a simple <span class=
600 "QUOTE">"."</span>), and you can define <span class=
601 "QUOTE">"character classes"</span> in square brackets which is
602 similar to the same regular expression technique. All of this can be
605 <div class="VARIABLELIST">
607 <dt><tt class="LITERAL">ad*.example.com</tt></dt>
610 <p>matches <span class="QUOTE">"adserver.example.com"</span>,
611 <span class="QUOTE">"ads.example.com"</span>, etc but not
612 <span class="QUOTE">"sfads.example.com"</span></p>
615 <dt><tt class="LITERAL">*ad*.example.com</tt></dt>
618 <p>matches all of the above, and then some.</p>
621 <dt><tt class="LITERAL">.?pix.com</tt></dt>
624 <p>matches <tt class="LITERAL">www.ipix.com</tt>, <tt class=
625 "LITERAL">pictures.epix.com</tt>, <tt class=
626 "LITERAL">a.b.c.d.e.upix.com</tt> etc.</p>
629 <dt><tt class="LITERAL">www[1-9a-ez].example.c*</tt></dt>
632 <p>matches <tt class="LITERAL">www1.example.com</tt>,
633 <tt class="LITERAL">www4.example.cc</tt>, <tt class=
634 "LITERAL">wwwd.example.cy</tt>, <tt class=
635 "LITERAL">wwwz.example.com</tt> etc., but <span class=
636 "emphasis"><i class="EMPHASIS">not</i></span> <tt class=
637 "LITERAL">wwww.example.com</tt>.</p>
642 <p>While flexible, this is not the sophistication of full regular
643 expression based syntax.</p>
647 <h3 class="SECT3"><a name="PATH-PATTERN" id="PATH-PATTERN">8.4.2. The
648 Path Pattern</a></h3>
650 <p><span class="APPLICATION">Privoxy</span> uses <span class=
651 "QUOTE">"modern"</span> POSIX 1003.2 <a href=
652 "http://en.wikipedia.org/wiki/Regular_expressions" target=
653 "_top"><span class="QUOTE">"Regular Expressions"</span></a> for
654 matching the path portion (after the slash), and is thus more
657 <p>There is an <a href="appendix.html#REGEX">Appendix</a> with a
658 brief quick-start into regular expressions, you also might want to
659 have a look at your operating system's documentation on regular
660 expressions (try <tt class="LITERAL">man re_format</tt>).</p>
662 <p>Note that the path pattern is automatically left-anchored at the
663 <span class="QUOTE">"/"</span>, i.e. it matches as if it would start
664 with a <span class="QUOTE">"^"</span> (regular expression speak for
665 the beginning of a line).</p>
667 <p>Please also note that matching in the path is <span class=
668 "emphasis"><i class="EMPHASIS">CASE INSENSITIVE</i></span> by
669 default, but you can switch to case sensitive at any point in the
670 pattern by using the <span class="QUOTE">"(?-i)"</span> switch:
671 <tt class="LITERAL">www.example.com/(?-i)PaTtErN.*</tt> will match
672 only documents whose path starts with <tt class=
673 "LITERAL">PaTtErN</tt> in <span class="emphasis"><i class=
674 "EMPHASIS">exactly</i></span> this capitalization.</p>
676 <div class="VARIABLELIST">
678 <dt><tt class="LITERAL">.example.com/.*</tt></dt>
681 <p>Is equivalent to just <span class=
682 "QUOTE">".example.com"</span>, since any documents within that
683 domain are matched with or without the <span class=
684 "QUOTE">".*"</span> regular expression. This is redundant</p>
687 <dt><tt class="LITERAL">.example.com/.*/index.html$</tt></dt>
690 <p>Will match any page in the domain of <span class=
691 "QUOTE">"example.com"</span> that is named <span class=
692 "QUOTE">"index.html"</span>, and that is part of some path. For
693 example, it matches <span class=
694 "QUOTE">"www.example.com/testing/index.html"</span> but NOT
695 <span class="QUOTE">"www.example.com/index.html"</span> because
696 the regular expression called for at least two <span class=
697 "QUOTE">"/'s"</span>, thus the path requirement. It also would
699 "QUOTE">"www.example.com/testing/index_html"</span>, because of
700 the special meta-character <span class="QUOTE">"."</span>.</p>
703 <dt><tt class="LITERAL">.example.com/(.*/)?index\.html$</tt></dt>
706 <p>This regular expression is conditional so it will match any
707 page named <span class="QUOTE">"index.html"</span> regardless
708 of path which in this case can have one or more <span class=
709 "QUOTE">"/'s"</span>. And this one must contain exactly
710 <span class="QUOTE">".html"</span> (but does not have to end
715 "LITERAL">.example.com/(.*/)(ads|banners?|junk)</tt></dt>
718 <p>This regular expression will match any path of <span class=
719 "QUOTE">"example.com"</span> that contains any of the words
720 <span class="QUOTE">"ads"</span>, <span class=
721 "QUOTE">"banner"</span>, <span class="QUOTE">"banners"</span>
722 (because of the <span class="QUOTE">"?"</span>) or <span class=
723 "QUOTE">"junk"</span>. The path does not have to end in these
724 words, just contain them.</p>
728 "LITERAL">.example.com/(.*/)(ads|banners?|junk)/.*\.(jpe?g|gif|png)$</tt></dt>
731 <p>This is very much the same as above, except now it must end
732 in either <span class="QUOTE">".jpg"</span>, <span class=
733 "QUOTE">".jpeg"</span>, <span class="QUOTE">".gif"</span> or
734 <span class="QUOTE">".png"</span>. So this one is limited to
735 common image formats.</p>
740 <p>There are many, many good examples to be found in <tt class=
741 "FILENAME">default.action</tt>, and more tutorials below in <a href=
742 "appendix.html#REGEX">Appendix on regular expressions</a>.</p>
746 <h3 class="SECT3"><a name="TAG-PATTERN" id="TAG-PATTERN">8.4.3. The
747 Request Tag Pattern</a></h3>
749 <p>Request tag patterns are used to change the applying actions based
750 on the request's tags. Tags can be created based on HTTP headers with
752 "actions-file.html#CLIENT-HEADER-TAGGER">client-header-tagger</a> or
754 "actions-file.html#SERVER-HEADER-TAGGER">server-header-tagger</a>
757 <p>Request tag patterns have to start with <span class=
758 "QUOTE">"TAG:"</span>, so <span class="APPLICATION">Privoxy</span>
759 can tell them apart from other patterns. Everything after the colon
760 including white space, is interpreted as a regular expression with
761 path pattern syntax, except that tag patterns aren't left-anchored
762 automatically (<span class="APPLICATION">Privoxy</span> doesn't
763 silently add a <span class="QUOTE">"^"</span>, you have to do it
764 yourself if you need it).</p>
766 <p>To match all requests that are tagged with <span class=
767 "QUOTE">"foo"</span> your pattern line should be <span class=
768 "QUOTE">"TAG:^foo$"</span>, <span class="QUOTE">"TAG:foo"</span>
769 would work as well, but it would also match requests whose tags
770 contain <span class="QUOTE">"foo"</span> somewhere. <span class=
771 "QUOTE">"TAG: foo"</span> wouldn't work as it requires white
774 <p>Sections can contain URL and request tag patterns at the same
775 time, but request tag patterns are checked after the URL patterns and
776 thus always overrule them, even if they are located before the URL
779 <p>Once a new request tag is added, Privoxy checks right away if it's
780 matched by one of the request tag patterns and updates the action
781 settings accordingly. As a result request tags can be used to
782 activate other tagger actions, as long as these other taggers look
783 for headers that haven't already be parsed.</p>
785 <p>For example you could tag client requests which use the <tt class=
786 "LITERAL">POST</tt> method, then use this tag to activate another
787 tagger that adds a tag if cookies are sent, and then use a block
788 action based on the cookie tag. This allows the outcome of one
789 action, to be input into a subsequent action. However if you'd
790 reverse the position of the described taggers, and activated the
791 method tagger based on the cookie tagger, no method tags would be
792 created. The method tagger would look for the request line, but at
793 the time the cookie tag is created, the request line has already been
796 <p>While this is a limitation you should be aware of, this kind of
797 indirection is seldom needed anyway and even the example doesn't make
802 <h3 class="SECT3"><a name="NEGATIVE-TAG-PATTERNS" id=
803 "NEGATIVE-TAG-PATTERNS">8.4.4. The Negative Request Tag
806 <p>To match requests that do not have a certain request tag, specify
807 a negative tag pattern by prefixing the tag pattern line with either
808 <span class="QUOTE">"NO-REQUEST-TAG:"</span> or <span class=
809 "QUOTE">"NO-RESPONSE-TAG:"</span> instead of <span class=
810 "QUOTE">"TAG:"</span>.</p>
812 <p>Negative request tag patterns created with <span class=
813 "QUOTE">"NO-REQUEST-TAG:"</span> are checked after all client headers
814 are scanned, the ones created with <span class=
815 "QUOTE">"NO-RESPONSE-TAG:"</span> are checked after all server
816 headers are scanned. In both cases all the created tags are
821 <h3 class="SECT3"><a name="CLIENT-TAG-PATTERN" id=
822 "CLIENT-TAG-PATTERN">8.4.5. The Client Tag Pattern</a></h3>
824 <div class="WARNING">
825 <table class="WARNING" border="1" width="100%">
827 <td align="center"><b>Warning</b></td>
832 <p>This is an experimental feature. The syntax is likely to
833 change in future versions.</p>
839 <p>Client tag patterns are not set based on HTTP headers but based on
840 the client's IP address. Users can enable them themselves, but the
841 Privoxy admin controls which tags are available and what their effect
844 <p>After a client-specific tag has been defined with the <a href=
845 "config.html#CLIENT-SPECIFIC-TAG">client-specific-tag</a>, directive,
846 action sections can be activated based on the tag by using a
847 CLIENT-TAG pattern. The CLIENT-TAG pattern is evaluated at the same
848 priority as URL patterns, as a result the last matching pattern wins.
849 Tags that are created based on client or server headers are evaluated
850 later on and can overrule CLIENT-TAG and URL patterns!</p>
852 <p>The tag is set for all requests that come from clients that
853 requested it to be set. Note that "clients" are differentiated by IP
854 address, if the IP address changes the tag has to be requested
857 <p>Clients can request tags to be set by using the CGI interface
858 <a href="http://config.privoxy.org/client-tags" target=
859 "_top">http://config.privoxy.org/client-tags</a>.</p>
863 <table border="0" bgcolor="#E0E0E0" width="100%">
867 # If the admin defined the client-specific-tag circumvent-blocks,
868 # and the request comes from a client that previously requested
869 # the tag to be set, overrule all previous +block actions that
870 # are enabled based on URL to CLIENT-TAG patterns.
872 CLIENT-TAG:^circumvent-blocks$
874 # This section is not overruled because it's located after
876 {+block{Nobody is supposed to request this.}}
877 example.org/blocked-example-page
886 <h2 class="SECT2"><a name="ACTIONS" id="ACTIONS">8.5. Actions</a></h2>
888 <p>All actions are disabled by default, until they are explicitly
889 enabled somewhere in an actions file. Actions are turned on if preceded
890 with a <span class="QUOTE">"+"</span>, and turned off if preceded with
891 a <span class="QUOTE">"-"</span>. So a <tt class="LITERAL">+action</tt>
892 means <span class="QUOTE">"do that action"</span>, e.g. <tt class=
893 "LITERAL">+block</tt> means <span class="QUOTE">"please block URLs that
894 match the following patterns"</span>, and <tt class=
895 "LITERAL">-block</tt> means <span class="QUOTE">"don't block URLs that
896 match the following patterns, even if <tt class="LITERAL">+block</tt>
897 previously applied."</span></p>
899 <p>Again, actions are invoked by placing them on a line, enclosed in
900 curly braces and separated by whitespace, like in <tt class=
901 "LITERAL">{+some-action -some-other-action{some-parameter}}</tt>,
902 followed by a list of URL patterns, one per line, to which they apply.
903 Together, the actions line and the following pattern lines make up a
904 section of the actions file.</p>
906 <p>Actions fall into three categories:</p>
910 <p>Boolean, i.e the action can only be <span class=
911 "QUOTE">"enabled"</span> or <span class="QUOTE">"disabled"</span>.
914 <table border="0" bgcolor="#E0E0E0" width="90%">
918 +<tt class="REPLACEABLE"><i>name</i></tt> # enable action <tt class=
919 "REPLACEABLE"><i>name</i></tt>
921 "REPLACEABLE"><i>name</i></tt> # disable action <tt class="REPLACEABLE"><i>name</i></tt>
927 <p>Example: <tt class="LITERAL">+handle-as-image</tt></p>
931 <p>Parameterized, where some value is required in order to enable
932 this type of action. Syntax:</p>
934 <table border="0" bgcolor="#E0E0E0" width="90%">
938 +<tt class="REPLACEABLE"><i>name</i></tt>{<tt class=
939 "REPLACEABLE"><i>param</i></tt>} # enable action and set parameter to <tt class="REPLACEABLE"><i>param</i></tt>,
940 # overwriting parameter from previous match if necessary
942 "REPLACEABLE"><i>name</i></tt> # disable action. The parameter can be omitted
948 <p>Note that if the URL matches multiple positive forms of a
949 parameterized action, the last match wins, i.e. the params from
950 earlier matches are simply ignored.</p>
952 <p>Example: <tt class="LITERAL">+hide-user-agent{Mozilla/5.0 (X11;
953 U; FreeBSD i386; en-US; rv:1.8.1.4) Gecko/20070602
954 Firefox/2.0.0.4}</tt></p>
958 <p>Multi-value. These look exactly like parameterized actions, but
959 they behave differently: If the action applies multiple times to
960 the same URL, but with different parameters, <span class=
961 "emphasis"><i class="EMPHASIS">all</i></span> the parameters from
962 <span class="emphasis"><i class="EMPHASIS">all</i></span> matches
963 are remembered. This is used for actions that can be executed for
964 the same request repeatedly, like adding multiple headers, or
965 filtering through multiple filters. Syntax:</p>
967 <table border="0" bgcolor="#E0E0E0" width="90%">
971 +<tt class="REPLACEABLE"><i>name</i></tt>{<tt class=
972 "REPLACEABLE"><i>param</i></tt>} # enable action and add <tt class=
973 "REPLACEABLE"><i>param</i></tt> to the list of parameters
974 -<tt class="REPLACEABLE"><i>name</i></tt>{<tt class=
975 "REPLACEABLE"><i>param</i></tt>} # remove the parameter <tt class=
976 "REPLACEABLE"><i>param</i></tt> from the list of parameters
977 # If it was the last one left, disable the action.
979 "REPLACEABLE"><i>-name</i></tt> # disable this action completely and remove all parameters from the list
985 <p>Examples: <tt class="LITERAL">+add-header{X-Fun-Header: Some
986 text}</tt> and <tt class=
987 "LITERAL">+filter{html-annoyances}</tt></p>
991 <p>If nothing is specified in any actions file, no <span class=
992 "QUOTE">"actions"</span> are taken. So in this case <span class=
993 "APPLICATION">Privoxy</span> would just be a normal, non-blocking,
994 non-filtering proxy. You must specifically enable the privacy and
995 blocking features you need (although the provided default actions files
996 will give a good starting point).</p>
998 <p>Later defined action sections always over-ride earlier ones of the
999 same type. So exceptions to any rules you make, should come in the
1000 latter part of the file (or in a file that is processed later when
1001 using multiple actions files such as <tt class=
1002 "FILENAME">user.action</tt>). For multi-valued actions, the actions are
1003 applied in the order they are specified. Actions files are processed in
1004 the order they are defined in <tt class="FILENAME">config</tt> (the
1005 default installation has three actions files). It also quite possible
1006 for any given URL to match more than one <span class=
1007 "QUOTE">"pattern"</span> (because of wildcards and regular
1008 expressions), and thus to trigger more than one set of actions! Last
1011 <p>The list of valid <span class="APPLICATION">Privoxy</span> actions
1015 <h4 class="SECT3"><a name="ADD-HEADER" id="ADD-HEADER">8.5.1.
1018 <div class="VARIABLELIST">
1020 <dt>Typical use:</dt>
1023 <p>Confuse log analysis, custom applications</p>
1029 <p>Sends a user defined HTTP header to the web server.</p>
1041 <p>Any string value is possible. Validity of the defined HTTP
1042 headers is not checked. It is recommended that you use the
1043 <span class="QUOTE">"<tt class="LITERAL">X-</tt>"</span> prefix
1044 for custom headers.</p>
1050 <p>This action may be specified multiple times, in order to
1051 define multiple headers. This is rarely needed for the typical
1052 user. If you don't know what <span class="QUOTE">"HTTP
1053 headers"</span> are, you definitely don't need to worry about
1056 <p>Headers added by this action are not modified by other
1060 <dt>Example usage:</dt>
1063 <table border="0" bgcolor="#E0E0E0" width="90%">
1066 <pre class="SCREEN">
1067 # Add a DNT ("Do not track") header to all requests,
1068 # event to those that already have one.
1070 # This is just an example, not a recommendation.
1072 # There is no reason to believe that user-tracking websites care
1073 # about the DNT header and depending on the User-Agent, adding the
1074 # header may make user-tracking easier.
1075 {+add-header{DNT: 1}}
1087 <h4 class="SECT3"><a name="BLOCK" id="BLOCK">8.5.2. block</a></h4>
1089 <div class="VARIABLELIST">
1091 <dt>Typical use:</dt>
1094 <p>Block ads or other unwanted content</p>
1100 <p>Requests for URLs to which this action applies are blocked,
1101 i.e. the requests are trapped by <span class=
1102 "APPLICATION">Privoxy</span> and the requested URL is never
1103 retrieved, but is answered locally with a substitute page or
1104 image, as determined by the <tt class="LITERAL"><a href=
1105 "actions-file.html#HANDLE-AS-IMAGE">handle-as-image</a></tt>,
1106 <tt class="LITERAL"><a href=
1107 "actions-file.html#SET-IMAGE-BLOCKER">set-image-blocker</a></tt>,
1108 and <tt class="LITERAL"><a href=
1109 "actions-file.html#HANDLE-AS-EMPTY-DOCUMENT">handle-as-empty-document</a></tt>
1116 <p>Parameterized.</p>
1122 <p>A block reason that should be given to the user.</p>
1128 <p><span class="APPLICATION">Privoxy</span> sends a special
1129 <span class="QUOTE">"BLOCKED"</span> page for requests to
1130 blocked pages. This page contains the block reason given as
1131 parameter, a link to find out why the block action applies, and
1132 a click-through to the blocked content (the latter only if the
1133 force feature is available and enabled).</p>
1135 <p>A very important exception occurs if <span class=
1136 "emphasis"><i class="EMPHASIS">both</i></span> <tt class=
1137 "LITERAL">block</tt> and <tt class="LITERAL"><a href=
1138 "actions-file.html#HANDLE-AS-IMAGE">handle-as-image</a></tt>,
1139 apply to the same request: it will then be replaced by an
1140 image. If <tt class="LITERAL"><a href=
1141 "actions-file.html#SET-IMAGE-BLOCKER">set-image-blocker</a></tt>
1142 (see below) also applies, the type of image will be determined
1143 by its parameter, if not, the standard checkerboard pattern is
1146 <p>It is important to understand this process, in order to
1147 understand how <span class="APPLICATION">Privoxy</span> deals
1148 with ads and other unwanted content. Blocking is a core
1149 feature, and one upon which various other features depend.</p>
1151 <p>The <tt class="LITERAL"><a href=
1152 "actions-file.html#FILTER">filter</a></tt> action can perform a
1153 very similar task, by <span class="QUOTE">"blocking"</span>
1154 banner images and other content through rewriting the relevant
1155 URLs in the document's HTML source, so they don't get requested
1156 in the first place. Note that this is a totally different
1157 technique, and it's easy to confuse the two.</p>
1160 <dt>Example usage (section):</dt>
1163 <table border="0" bgcolor="#E0E0E0" width="90%">
1166 <pre class="SCREEN">
1167 {+block{No nasty stuff for you.}}
1168 # Block and replace with "blocked" page
1169 .nasty-stuff.example.com
1171 {+block{Doubleclick banners.} +handle-as-image}
1172 # Block and replace with image
1176 {+block{Layered ads.} +handle-as-empty-document}
1177 # Block and then ignore
1178 adserver.example.net/.*\.js$
1189 <h4 class="SECT3"><a name="CHANGE-X-FORWARDED-FOR" id=
1190 "CHANGE-X-FORWARDED-FOR">8.5.3. change-x-forwarded-for</a></h4>
1192 <div class="VARIABLELIST">
1194 <dt>Typical use:</dt>
1197 <p>Improve privacy by not forwarding the source of the request
1198 in the HTTP headers.</p>
1204 <p>Deletes the <span class="QUOTE">"X-Forwarded-For:"</span>
1205 HTTP header from the client request, or adds a new one.</p>
1211 <p>Parameterized.</p>
1219 <p><span class="QUOTE">"block"</span> to delete the
1224 <p><span class="QUOTE">"add"</span> to create the header
1225 (or append the client's IP address to an already existing
1234 <p>It is safe and recommended to use <tt class=
1235 "LITERAL">block</tt>.</p>
1237 <p>Forwarding the source address of the request may make sense
1238 in some multi-user setups but is also a privacy risk.</p>
1241 <dt>Example usage:</dt>
1244 <table border="0" bgcolor="#E0E0E0" width="90%">
1247 <pre class="SCREEN">
1248 +change-x-forwarded-for{block}
1259 <h4 class="SECT3"><a name="CLIENT-HEADER-FILTER" id=
1260 "CLIENT-HEADER-FILTER">8.5.4. client-header-filter</a></h4>
1262 <div class="VARIABLELIST">
1264 <dt>Typical use:</dt>
1267 <p>Rewrite or remove single client headers.</p>
1273 <p>All client headers to which this action applies are filtered
1274 on-the-fly through the specified regular expression based
1287 <p>The name of a client-header filter, as defined in one of the
1288 <a href="filter-file.html">filter files</a>.</p>
1294 <p>Client-header filters are applied to each header on its own,
1295 not to all at once. This makes it easier to diagnose problems,
1296 but on the downside you can't write filters that only change
1297 header x if header y's value is z. You can do that by using
1300 <p>Client-header filters are executed after the other header
1301 actions have finished and use their output as input.</p>
1303 <p>If the request URI gets changed, <span class=
1304 "APPLICATION">Privoxy</span> will detect that and use the new
1305 one. This can be used to rewrite the request destination behind
1306 the client's back, for example to specify a Tor exit relay for
1307 certain requests.</p>
1309 <p>Please refer to the <a href="filter-file.html">filter file
1310 chapter</a> to learn which client-header filters are available
1311 by default, and how to create your own.</p>
1314 <dt>Example usage (section):</dt>
1317 <table border="0" bgcolor="#E0E0E0" width="90%">
1320 <pre class="SCREEN">
1321 # Hide Tor exit notation in Host and Referer Headers
1322 {+client-header-filter{hide-tor-exit-notation}}
1335 <h4 class="SECT3"><a name="CLIENT-HEADER-TAGGER" id=
1336 "CLIENT-HEADER-TAGGER">8.5.5. client-header-tagger</a></h4>
1338 <div class="VARIABLELIST">
1340 <dt>Typical use:</dt>
1343 <p>Block requests based on their headers.</p>
1349 <p>Client headers to which this action applies are filtered
1350 on-the-fly through the specified regular expression based
1351 substitutions, the result is used as tag.</p>
1363 <p>The name of a client-header tagger, as defined in one of the
1364 <a href="filter-file.html">filter files</a>.</p>
1370 <p>Client-header taggers are applied to each header on its own,
1371 and as the header isn't modified, each tagger <span class=
1372 "QUOTE">"sees"</span> the original.</p>
1374 <p>Client-header taggers are the first actions that are
1375 executed and their tags can be used to control every other
1379 <dt>Example usage (section):</dt>
1382 <table border="0" bgcolor="#E0E0E0" width="90%">
1385 <pre class="SCREEN">
1386 # Tag every request with the User-Agent header
1387 {+client-header-tagger{user-agent}}
1390 # Tagging itself doesn't change the action
1391 # settings, sections with TAG patterns do:
1393 # If it's a download agent, use a different forwarding proxy,
1394 # show the real User-Agent and make sure resume works.
1395 {+forward-override{forward-socks5 10.0.0.2:2222 .} \
1396 -hide-if-modified-since \
1397 -overwrite-last-modified \
1402 TAG:^User-Agent: NetBSD-ftp/
1403 TAG:^User-Agent: Novell ZYPP Installer
1404 TAG:^User-Agent: RPM APT-HTTP/
1405 TAG:^User-Agent: fetch libfetch/
1406 TAG:^User-Agent: Ubuntu APT-HTTP/
1407 TAG:^User-Agent: MPlayer/
1414 <table border="0" bgcolor="#E0E0E0" width="90%">
1417 <pre class="SCREEN">
1418 # Tag all requests with the Range header set
1419 {+client-header-tagger{range-requests}}
1422 # Disable filtering for the tagged requests.
1424 # With filtering enabled Privoxy would remove the Range headers
1425 # to be able to filter the whole response. The downside is that
1426 # it prevents clients from resuming downloads or skipping over
1427 # parts of multimedia files.
1428 {-filter -deanimate-gifs}
1441 <h4 class="SECT3"><a name="CONTENT-TYPE-OVERWRITE" id=
1442 "CONTENT-TYPE-OVERWRITE">8.5.6. content-type-overwrite</a></h4>
1444 <div class="VARIABLELIST">
1446 <dt>Typical use:</dt>
1449 <p>Stop useless download menus from popping up, or change the
1450 browser's rendering mode</p>
1456 <p>Replaces the <span class="QUOTE">"Content-Type:"</span> HTTP
1463 <p>Parameterized.</p>
1475 <p>The <span class="QUOTE">"Content-Type:"</span> HTTP server
1476 header is used by the browser to decide what to do with the
1477 document. The value of this header can cause the browser to
1478 open a download menu instead of displaying the document by
1479 itself, even if the document's format is supported by the
1482 <p>The declared content type can also affect which rendering
1483 mode the browser chooses. If XHTML is delivered as <span class=
1484 "QUOTE">"text/html"</span>, many browsers treat it as yet
1485 another broken HTML document. If it is send as <span class=
1486 "QUOTE">"application/xml"</span>, browsers with XHTML support
1487 will only display it, if the syntax is correct.</p>
1489 <p>If you see a web site that proudly uses XHTML buttons, but
1490 sets <span class="QUOTE">"Content-Type: text/html"</span>, you
1491 can use <span class="APPLICATION">Privoxy</span> to overwrite
1492 it with <span class="QUOTE">"application/xml"</span> and
1493 validate the web master's claim inside your XHTML-supporting
1494 browser. If the syntax is incorrect, the browser will complain
1497 <p>You can also go the opposite direction: if your browser
1498 prints error messages instead of rendering a document falsely
1499 declared as XHTML, you can overwrite the content type with
1500 <span class="QUOTE">"text/html"</span> and have it rendered as
1501 broken HTML document.</p>
1503 <p>By default <tt class="LITERAL">content-type-overwrite</tt>
1504 only replaces <span class="QUOTE">"Content-Type:"</span>
1505 headers that look like some kind of text. If you want to
1506 overwrite it unconditionally, you have to combine it with
1507 <tt class="LITERAL"><a href=
1508 "actions-file.html#FORCE-TEXT-MODE">force-text-mode</a></tt>.
1509 This limitation exists for a reason, think twice before
1510 circumventing it.</p>
1512 <p>Most of the time it's easier to replace this action with a
1513 custom <tt class="LITERAL"><a href=
1514 "actions-file.html#SERVER-HEADER-FILTER">server-header
1515 filter</a></tt>. It allows you to activate it for every
1516 document of a certain site and it will still only replace the
1517 content types you aimed at.</p>
1519 <p>Of course you can apply <tt class=
1520 "LITERAL">content-type-overwrite</tt> to a whole site and then
1521 make URL based exceptions, but it's a lot more work to get the
1525 <dt>Example usage (sections):</dt>
1528 <table border="0" bgcolor="#E0E0E0" width="90%">
1531 <pre class="SCREEN">
1532 # Check if www.example.net/ really uses valid XHTML
1533 { +content-type-overwrite{application/xml} }
1536 # but leave the content type unmodified if the URL looks like a style sheet
1537 {-content-type-overwrite}
1538 www.example.net/.*\.css$
1539 www.example.net/.*style
1550 <h4 class="SECT3"><a name="CRUNCH-CLIENT-HEADER" id=
1551 "CRUNCH-CLIENT-HEADER">8.5.7. crunch-client-header</a></h4>
1553 <div class="VARIABLELIST">
1555 <dt>Typical use:</dt>
1558 <p>Remove a client header <span class=
1559 "APPLICATION">Privoxy</span> has no dedicated action for.</p>
1565 <p>Deletes every header sent by the client that contains the
1566 string the user supplied as parameter.</p>
1572 <p>Parameterized.</p>
1584 <p>This action allows you to block client headers for which no
1585 dedicated <span class="APPLICATION">Privoxy</span> action
1586 exists. <span class="APPLICATION">Privoxy</span> will remove
1587 every client header that contains the string you supplied as
1590 <p>Regular expressions are <span class="emphasis"><i class=
1591 "EMPHASIS">not supported</i></span> and you can't use this
1592 action to block different headers in the same request, unless
1593 they contain the same string.</p>
1595 <p><tt class="LITERAL">crunch-client-header</tt> is only meant
1596 for quick tests. If you have to block several different
1597 headers, or only want to modify parts of them, you should use a
1598 <tt class="LITERAL"><a href=
1599 "actions-file.html#CLIENT-HEADER-FILTER">client-header
1600 filter</a></tt>.</p>
1602 <div class="WARNING">
1603 <table class="WARNING" border="1" width="90%">
1605 <td align="center"><b>Warning</b></td>
1610 <p>Don't block any header without understanding the
1618 <dt>Example usage (section):</dt>
1621 <table border="0" bgcolor="#E0E0E0" width="90%">
1624 <pre class="SCREEN">
1625 # Block the non-existent "Privacy-Violation:" client header
1626 { +crunch-client-header{Privacy-Violation:} }
1639 <h4 class="SECT3"><a name="CRUNCH-IF-NONE-MATCH" id=
1640 "CRUNCH-IF-NONE-MATCH">8.5.8. crunch-if-none-match</a></h4>
1642 <div class="VARIABLELIST">
1644 <dt>Typical use:</dt>
1647 <p>Prevent yet another way to track the user's steps between
1654 <p>Deletes the <span class="QUOTE">"If-None-Match:"</span> HTTP
1673 <p>Removing the <span class="QUOTE">"If-None-Match:"</span>
1674 HTTP client header is useful for filter testing, where you want
1675 to force a real reload instead of getting status code
1676 <span class="QUOTE">"304"</span> which would cause the browser
1677 to use a cached copy of the page.</p>
1679 <p>It is also useful to make sure the header isn't used as a
1680 cookie replacement (unlikely but possible).</p>
1682 <p>Blocking the <span class="QUOTE">"If-None-Match:"</span>
1683 header shouldn't cause any caching problems, as long as the
1684 <span class="QUOTE">"If-Modified-Since:"</span> header isn't
1685 blocked or missing as well.</p>
1687 <p>It is recommended to use this action together with
1688 <tt class="LITERAL"><a href=
1689 "actions-file.html#HIDE-IF-MODIFIED-SINCE">hide-if-modified-since</a></tt>
1690 and <tt class="LITERAL"><a href=
1691 "actions-file.html#OVERWRITE-LAST-MODIFIED">overwrite-last-modified</a></tt>.</p>
1694 <dt>Example usage (section):</dt>
1697 <table border="0" bgcolor="#E0E0E0" width="90%">
1700 <pre class="SCREEN">
1701 # Let the browser revalidate cached documents but don't
1702 # allow the server to use the revalidation headers for user tracking.
1703 {+hide-if-modified-since{-60} \
1704 +overwrite-last-modified{randomize} \
1705 +crunch-if-none-match}
1717 <h4 class="SECT3"><a name="CRUNCH-INCOMING-COOKIES" id=
1718 "CRUNCH-INCOMING-COOKIES">8.5.9. crunch-incoming-cookies</a></h4>
1720 <div class="VARIABLELIST">
1722 <dt>Typical use:</dt>
1725 <p>Prevent the web server from setting HTTP cookies on your
1732 <p>Deletes any <span class="QUOTE">"Set-Cookie:"</span> HTTP
1733 headers from server replies.</p>
1751 <p>This action is only concerned with <span class=
1752 "emphasis"><i class="EMPHASIS">incoming</i></span> HTTP
1753 cookies. For <span class="emphasis"><i class=
1754 "EMPHASIS">outgoing</i></span> HTTP cookies, use <tt class=
1756 "actions-file.html#CRUNCH-OUTGOING-COOKIES">crunch-outgoing-cookies</a></tt>.
1757 Use <span class="emphasis"><i class="EMPHASIS">both</i></span>
1758 to disable HTTP cookies completely.</p>
1760 <p>It makes <span class="emphasis"><i class="EMPHASIS">no sense
1761 at all</i></span> to use this action in conjunction with the
1762 <tt class="LITERAL"><a href=
1763 "actions-file.html#SESSION-COOKIES-ONLY">session-cookies-only</a></tt>
1764 action, since it would prevent the session cookies from being
1765 set. See also <tt class="LITERAL"><a href=
1766 "actions-file.html#FILTER-CONTENT-COOKIES">filter-content-cookies</a></tt>.</p>
1769 <dt>Example usage:</dt>
1772 <table border="0" bgcolor="#E0E0E0" width="90%">
1775 <pre class="SCREEN">
1776 +crunch-incoming-cookies
1787 <h4 class="SECT3"><a name="CRUNCH-SERVER-HEADER" id=
1788 "CRUNCH-SERVER-HEADER">8.5.10. crunch-server-header</a></h4>
1790 <div class="VARIABLELIST">
1792 <dt>Typical use:</dt>
1795 <p>Remove a server header <span class=
1796 "APPLICATION">Privoxy</span> has no dedicated action for.</p>
1802 <p>Deletes every header sent by the server that contains the
1803 string the user supplied as parameter.</p>
1809 <p>Parameterized.</p>
1821 <p>This action allows you to block server headers for which no
1822 dedicated <span class="APPLICATION">Privoxy</span> action
1823 exists. <span class="APPLICATION">Privoxy</span> will remove
1824 every server header that contains the string you supplied as
1827 <p>Regular expressions are <span class="emphasis"><i class=
1828 "EMPHASIS">not supported</i></span> and you can't use this
1829 action to block different headers in the same request, unless
1830 they contain the same string.</p>
1832 <p><tt class="LITERAL">crunch-server-header</tt> is only meant
1833 for quick tests. If you have to block several different
1834 headers, or only want to modify parts of them, you should use a
1835 custom <tt class="LITERAL"><a href=
1836 "actions-file.html#SERVER-HEADER-FILTER">server-header
1837 filter</a></tt>.</p>
1839 <div class="WARNING">
1840 <table class="WARNING" border="1" width="90%">
1842 <td align="center"><b>Warning</b></td>
1847 <p>Don't block any header without understanding the
1855 <dt>Example usage (section):</dt>
1858 <table border="0" bgcolor="#E0E0E0" width="90%">
1861 <pre class="SCREEN">
1862 # Crunch server headers that try to prevent caching
1863 { +crunch-server-header{no-cache} }
1875 <h4 class="SECT3"><a name="CRUNCH-OUTGOING-COOKIES" id=
1876 "CRUNCH-OUTGOING-COOKIES">8.5.11. crunch-outgoing-cookies</a></h4>
1878 <div class="VARIABLELIST">
1880 <dt>Typical use:</dt>
1883 <p>Prevent the web server from reading any HTTP cookies from
1890 <p>Deletes any <span class="QUOTE">"Cookie:"</span> HTTP
1891 headers from client requests.</p>
1909 <p>This action is only concerned with <span class=
1910 "emphasis"><i class="EMPHASIS">outgoing</i></span> HTTP
1911 cookies. For <span class="emphasis"><i class=
1912 "EMPHASIS">incoming</i></span> HTTP cookies, use <tt class=
1914 "actions-file.html#CRUNCH-INCOMING-COOKIES">crunch-incoming-cookies</a></tt>.
1915 Use <span class="emphasis"><i class="EMPHASIS">both</i></span>
1916 to disable HTTP cookies completely.</p>
1918 <p>It makes <span class="emphasis"><i class="EMPHASIS">no sense
1919 at all</i></span> to use this action in conjunction with the
1920 <tt class="LITERAL"><a href=
1921 "actions-file.html#SESSION-COOKIES-ONLY">session-cookies-only</a></tt>
1922 action, since it would prevent the session cookies from being
1926 <dt>Example usage:</dt>
1929 <table border="0" bgcolor="#E0E0E0" width="90%">
1932 <pre class="SCREEN">
1933 +crunch-outgoing-cookies
1944 <h4 class="SECT3"><a name="DEANIMATE-GIFS" id=
1945 "DEANIMATE-GIFS">8.5.12. deanimate-gifs</a></h4>
1947 <div class="VARIABLELIST">
1949 <dt>Typical use:</dt>
1952 <p>Stop those annoying, distracting animated GIF images.</p>
1958 <p>De-animate GIF animations, i.e. reduce them to their first
1965 <p>Parameterized.</p>
1971 <p><span class="QUOTE">"last"</span> or <span class=
1972 "QUOTE">"first"</span></p>
1978 <p>This will also shrink the images considerably (in bytes, not
1979 pixels!). If the option <span class="QUOTE">"first"</span> is
1980 given, the first frame of the animation is used as the
1981 replacement. If <span class="QUOTE">"last"</span> is given, the
1982 last frame of the animation is used instead, which probably
1983 makes more sense for most banner animations, but also has the
1984 risk of not showing the entire last frame (if it is only a
1985 delta to an earlier frame).</p>
1987 <p>You can safely use this action with patterns that will also
1988 match non-GIF objects, because no attempt will be made at
1989 anything that doesn't look like a GIF.</p>
1992 <dt>Example usage:</dt>
1995 <table border="0" bgcolor="#E0E0E0" width="90%">
1998 <pre class="SCREEN">
1999 +deanimate-gifs{last}
2010 <h4 class="SECT3"><a name="DOWNGRADE-HTTP-VERSION" id=
2011 "DOWNGRADE-HTTP-VERSION">8.5.13. downgrade-http-version</a></h4>
2013 <div class="VARIABLELIST">
2015 <dt>Typical use:</dt>
2018 <p>Work around (very rare) problems with HTTP/1.1</p>
2024 <p>Downgrades HTTP/1.1 client requests and server replies to
2043 <p>This is a left-over from the time when <span class=
2044 "APPLICATION">Privoxy</span> didn't support important HTTP/1.1
2045 features well. It is left here for the unlikely case that you
2046 experience HTTP/1.1-related problems with some server out
2049 <p>Note that enabling this action is only a workaround. It
2050 should not be enabled for sites that work without it. While it
2051 shouldn't break any pages, it has an (usually negative)
2052 performance impact.</p>
2054 <p>If you come across a site where enabling this action helps,
2055 please report it, so the cause of the problem can be analyzed.
2056 If the problem turns out to be caused by a bug in <span class=
2057 "APPLICATION">Privoxy</span> it should be fixed so the
2058 following release works without the work around.</p>
2061 <dt>Example usage (section):</dt>
2064 <table border="0" bgcolor="#E0E0E0" width="90%">
2067 <pre class="SCREEN">
2068 {+downgrade-http-version}
2069 problem-host.example.com
2080 <h4 class="SECT3"><a name="EXTERNAL-FILTER" id=
2081 "EXTERNAL-FILTER">8.5.14. external-filter</a></h4>
2083 <div class="VARIABLELIST">
2085 <dt>Typical use:</dt>
2088 <p>Modify content using a programming language of your
2095 <p>All instances of text-based type, most notably HTML and
2096 JavaScript, to which this action applies, can be filtered
2097 on-the-fly through the specified external filter. By default
2098 plain text documents are exempted from filtering, because web
2099 servers often use the <tt class="LITERAL">text/plain</tt> MIME
2100 type for all files whose type they don't know.)</p>
2112 <p>The name of an external content filter, as defined in the
2113 <a href="filter-file.html">filter file</a>. External filters
2114 can be defined in one or more files as defined by the
2115 <tt class="LITERAL"><a href=
2116 "config.html#FILTERFILE">filterfile</a></tt> option in the
2117 <a href="config.html">config file</a>.</p>
2119 <p>When used in its negative form, and without parameters,
2120 <span class="emphasis"><i class="EMPHASIS">all</i></span>
2121 filtering with external filters is completely disabled.</p>
2127 <p>External filters are scripts or programs that can modify the
2128 content in case common <tt class="LITERAL"><a href=
2129 "actions-file.html#FILTER">filters</a></tt> aren't powerful
2130 enough. With the exception that this action doesn't use
2131 pcrs-based filters, the notes in the <tt class=
2132 "LITERAL"><a href="actions-file.html#FILTER">filter</a></tt>
2135 <div class="WARNING">
2136 <table class="WARNING" border="1" width="90%">
2138 <td align="center"><b>Warning</b></td>
2143 <p>Currently external filters are executed with
2144 <span class="APPLICATION">Privoxy</span>'s privileges.
2145 Only use external filters you understand and trust.</p>
2151 <p>This feature is experimental, the <tt class=
2153 "filter-file.html#EXTERNAL-FILTER-SYNTAX">syntax</a></tt> may
2154 change in the future.</p>
2157 <dt>Example usage:</dt>
2160 <table border="0" bgcolor="#E0E0E0" width="90%">
2163 <pre class="SCREEN">
2164 +external-filter{fancy-filter}
2175 <h4 class="SECT3"><a name="FAST-REDIRECTS" id=
2176 "FAST-REDIRECTS">8.5.15. fast-redirects</a></h4>
2178 <div class="VARIABLELIST">
2180 <dt>Typical use:</dt>
2183 <p>Fool some click-tracking scripts and speed up indirect
2190 <p>Detects redirection URLs and redirects the browser without
2191 contacting the redirection server first.</p>
2197 <p>Parameterized.</p>
2205 <p><span class="QUOTE">"simple-check"</span> to just search
2206 for the string <span class="QUOTE">"http://"</span> to
2207 detect redirection URLs.</p>
2211 <p><span class="QUOTE">"check-decoded-url"</span> to decode
2212 URLs (if necessary) before searching for redirection
2221 <p>Many sites, like yahoo.com, don't just link to other sites.
2222 Instead, they will link to some script on their own servers,
2223 giving the destination as a parameter, which will then redirect
2224 you to the final target. URLs resulting from this scheme
2225 typically look like: <span class=
2226 "QUOTE">"http://www.example.org/click-tracker.cgi?target=http%3a//www.example.net/"</span>.</p>
2228 <p>Sometimes, there are even multiple consecutive redirects
2229 encoded in the URL. These redirections via scripts make your
2230 web browsing more traceable, since the server from which you
2231 follow such a link can see where you go to. Apart from that,
2232 valuable bandwidth and time is wasted, while your browser asks
2233 the server for one redirect after the other. Plus, it feeds the
2236 <p>This feature is currently not very smart and is scheduled
2237 for improvement. If it is enabled by default, you will have to
2238 create some exceptions to this action. It can lead to failures
2239 in several ways:</p>
2241 <p>Not every URLs with other URLs as parameters is evil. Some
2242 sites offer a real service that requires this information to
2243 work. For example a validation service needs to know, which
2244 document to validate. <tt class="LITERAL">fast-redirects</tt>
2245 assumes that every URL parameter that looks like another URL is
2246 a redirection target, and will always redirect to the last one.
2247 Most of the time the assumption is correct, but if it isn't,
2248 the user gets redirected anyway.</p>
2250 <p>Another failure occurs if the URL contains other parameters
2251 after the URL parameter. The URL: <span class=
2252 "QUOTE">"http://www.example.org/?redirect=http%3a//www.example.net/&foo=bar"</span>.
2253 contains the redirection URL <span class=
2254 "QUOTE">"http://www.example.net/"</span>, followed by another
2255 parameter. <tt class="LITERAL">fast-redirects</tt> doesn't know
2256 that and will cause a redirect to <span class=
2257 "QUOTE">"http://www.example.net/&foo=bar"</span>. Depending
2258 on the target server configuration, the parameter will be
2259 silently ignored or lead to a <span class="QUOTE">"page not
2260 found"</span> error. You can prevent this problem by first
2261 using the <tt class="LITERAL"><a href=
2262 "actions-file.html#REDIRECT">redirect</a></tt> action to remove
2263 the last part of the URL, but it requires a little effort.</p>
2265 <p>To detect a redirection URL, <tt class=
2266 "LITERAL">fast-redirects</tt> only looks for the string
2267 <span class="QUOTE">"http://"</span>, either in plain text
2268 (invalid but often used) or encoded as <span class=
2269 "QUOTE">"http%3a//"</span>. Some sites use their own URL
2270 encoding scheme, encrypt the address of the target server or
2271 replace it with a database id. In theses cases <tt class=
2272 "LITERAL">fast-redirects</tt> is fooled and the request reaches
2273 the redirection server where it probably gets logged.</p>
2276 <dt>Example usage:</dt>
2279 <table border="0" bgcolor="#E0E0E0" width="90%">
2282 <pre class="SCREEN">
2283 { +fast-redirects{simple-check} }
2286 { +fast-redirects{check-decoded-url} }
2287 another.example.com/testing
2298 <h4 class="SECT3"><a name="FILTER" id="FILTER">8.5.16.
2301 <div class="VARIABLELIST">
2303 <dt>Typical use:</dt>
2306 <p>Get rid of HTML and JavaScript annoyances, banner
2307 advertisements (by size), do fun text replacements, add
2308 personalized effects, etc.</p>
2314 <p>All instances of text-based type, most notably HTML and
2315 JavaScript, to which this action applies, can be filtered
2316 on-the-fly through the specified regular expression based
2317 substitutions. (Note: as of version 3.0.3 plain text documents
2318 are exempted from filtering, because web servers often use the
2319 <tt class="LITERAL">text/plain</tt> MIME type for all files
2320 whose type they don't know.)</p>
2332 <p>The name of a content filter, as defined in the <a href=
2333 "filter-file.html">filter file</a>. Filters can be defined in
2334 one or more files as defined by the <tt class=
2335 "LITERAL"><a href="config.html#FILTERFILE">filterfile</a></tt>
2336 option in the <a href="config.html">config file</a>. <tt class=
2337 "FILENAME">default.filter</tt> is the collection of filters
2338 supplied by the developers. Locally defined filters should go
2339 in their own file, such as <tt class=
2340 "FILENAME">user.filter</tt>.</p>
2342 <p>When used in its negative form, and without parameters,
2343 <span class="emphasis"><i class="EMPHASIS">all</i></span>
2344 filtering is completely disabled.</p>
2350 <p>For your convenience, there are a number of pre-defined
2351 filters available in the distribution filter file that you can
2352 use. See the examples below for a list.</p>
2354 <p>Filtering requires buffering the page content, which may
2355 appear to slow down page rendering since nothing is displayed
2356 until all content has passed the filters. (The total time until
2357 the page is completely rendered doesn't change much, but it may
2358 be perceived as slower since the page is not incrementally
2359 displayed.) This effect will be more noticeable on slower
2362 <p><span class="QUOTE">"Rolling your own"</span> filters
2363 requires a knowledge of <a href=
2364 "http://en.wikipedia.org/wiki/Regular_expressions" target=
2365 "_top"><span class="QUOTE">"Regular Expressions"</span></a> and
2366 <a href="http://en.wikipedia.org/wiki/Html" target=
2367 "_top"><span class="QUOTE">"HTML"</span></a>. This is very
2368 powerful feature, and potentially very intrusive. Filters
2369 should be used with caution, and where an equivalent
2370 <span class="QUOTE">"action"</span> is not available.</p>
2372 <p>The amount of data that can be filtered is limited to the
2373 <tt class="LITERAL"><a href=
2374 "config.html#BUFFER-LIMIT">buffer-limit</a></tt> option in the
2375 main <a href="config.html">config file</a>. The default is 4096
2376 KB (4 Megs). Once this limit is exceeded, the buffered data,
2377 and all pending data, is passed through unfiltered.</p>
2379 <p>Inappropriate MIME types, such as zipped files, are not
2380 filtered at all. (Again, only text-based types except plain
2381 text). Encrypted SSL data (from HTTPS servers) cannot be
2382 filtered either, since this would violate the integrity of the
2383 secure transaction. In some situations it might be necessary to
2384 protect certain text, like source code, from filtering by
2385 defining appropriate <tt class="LITERAL">-filter</tt>
2388 <p>Compressed content can't be filtered either, but if
2389 <span class="APPLICATION">Privoxy</span> is compiled with zlib
2390 support and a supported compression algorithm is used (gzip or
2391 deflate), <span class="APPLICATION">Privoxy</span> can first
2392 decompress the content and then filter it.</p>
2394 <p>If you use a <span class="APPLICATION">Privoxy</span>
2395 version without zlib support, but want filtering to work on as
2396 much documents as possible, even those that would normally be
2397 sent compressed, you must use the <tt class="LITERAL"><a href=
2398 "actions-file.html#PREVENT-COMPRESSION">prevent-compression</a></tt>
2399 action in conjunction with <tt class="LITERAL">filter</tt>.</p>
2401 <p>Content filtering can achieve some of the same effects as
2402 the <tt class="LITERAL"><a href=
2403 "actions-file.html#BLOCK">block</a></tt> action, i.e. it can be
2404 used to block ads and banners. But the mechanism works quite
2405 differently. One effective use, is to block ad banners based on
2406 their size (see below), since many of these seem to be somewhat
2409 <p><a href="contact.html">Feedback</a> with suggestions for new
2410 or improved filters is particularly welcome!</p>
2412 <p>The below list has only the names and a one-line description
2413 of each predefined filter. There are <a href=
2414 "filter-file.html#PREDEFINED-FILTERS">more verbose
2415 explanations</a> of what these filters do in the <a href=
2416 "filter-file.html">filter file chapter</a>.</p>
2419 <dt>Example usage (with filters from the distribution <tt class=
2420 "FILENAME">default.filter</tt> file). See <a href=
2421 "filter-file.html#PREDEFINED-FILTERS">the Predefined Filters
2422 section</a> for more explanation on each:</dt>
2425 <p><a name="FILTER-JS-ANNOYANCES" id=
2426 "FILTER-JS-ANNOYANCES"></a></p>
2428 <table border="0" bgcolor="#E0E0E0" width="90%">
2431 <pre class="SCREEN">
2432 +filter{js-annoyances} # Get rid of particularly annoying JavaScript abuse.
2438 <p><a name="FILTER-JS-EVENTS" id="FILTER-JS-EVENTS"></a></p>
2440 <table border="0" bgcolor="#E0E0E0" width="90%">
2443 <pre class="SCREEN">
2444 +filter{js-events} # Kill JavaScript event bindings and timers (Radically destructive! Only for extra nasty sites).
2450 <p><a name="FILTER-HTML-ANNOYANCES" id=
2451 "FILTER-HTML-ANNOYANCES"></a></p>
2453 <table border="0" bgcolor="#E0E0E0" width="90%">
2456 <pre class="SCREEN">
2457 +filter{html-annoyances} # Get rid of particularly annoying HTML abuse.
2463 <p><a name="FILTER-CONTENT-COOKIES" id=
2464 "FILTER-CONTENT-COOKIES"></a></p>
2466 <table border="0" bgcolor="#E0E0E0" width="90%">
2469 <pre class="SCREEN">
2470 +filter{content-cookies} # Kill cookies that come in the HTML or JS content.
2476 <p><a name="FILTER-REFRESH-TAGS" id=
2477 "FILTER-REFRESH-TAGS"></a></p>
2479 <table border="0" bgcolor="#E0E0E0" width="90%">
2482 <pre class="SCREEN">
2483 +filter{refresh-tags} # Kill automatic refresh tags if refresh time is larger than 9 seconds.
2489 <p><a name="FILTER-UNSOLICITED-POPUPS" id=
2490 "FILTER-UNSOLICITED-POPUPS"></a></p>
2492 <table border="0" bgcolor="#E0E0E0" width="90%">
2495 <pre class="SCREEN">
2496 +filter{unsolicited-popups} # Disable only unsolicited pop-up windows.
2502 <p><a name="FILTER-ALL-POPUPS" id="FILTER-ALL-POPUPS"></a></p>
2504 <table border="0" bgcolor="#E0E0E0" width="90%">
2507 <pre class="SCREEN">
2508 +filter{all-popups} # Kill all popups in JavaScript and HTML.
2514 <p><a name="FILTER-IMG-REORDER" id=
2515 "FILTER-IMG-REORDER"></a></p>
2517 <table border="0" bgcolor="#E0E0E0" width="90%">
2520 <pre class="SCREEN">
2521 +filter{img-reorder} # Reorder attributes in <img> tags to make the banners-by-* filters more effective.
2527 <p><a name="FILTER-BANNERS-BY-SIZE" id=
2528 "FILTER-BANNERS-BY-SIZE"></a></p>
2530 <table border="0" bgcolor="#E0E0E0" width="90%">
2533 <pre class="SCREEN">
2534 +filter{banners-by-size} # Kill banners by size.
2540 <p><a name="FILTER-BANNERS-BY-LINK" id=
2541 "FILTER-BANNERS-BY-LINK"></a></p>
2543 <table border="0" bgcolor="#E0E0E0" width="90%">
2546 <pre class="SCREEN">
2547 +filter{banners-by-link} # Kill banners by their links to known clicktrackers.
2553 <p><a name="FILTER-WEBBUGS" id="FILTER-WEBBUGS"></a></p>
2555 <table border="0" bgcolor="#E0E0E0" width="90%">
2558 <pre class="SCREEN">
2559 +filter{webbugs} # Squish WebBugs (1x1 invisible GIFs used for user tracking).
2565 <p><a name="FILTER-TINY-TEXTFORMS" id=
2566 "FILTER-TINY-TEXTFORMS"></a></p>
2568 <table border="0" bgcolor="#E0E0E0" width="90%">
2571 <pre class="SCREEN">
2572 +filter{tiny-textforms} # Extend those tiny textareas up to 40x80 and kill the hard wrap.
2578 <p><a name="FILTER-JUMPING-WINDOWS" id=
2579 "FILTER-JUMPING-WINDOWS"></a></p>
2581 <table border="0" bgcolor="#E0E0E0" width="90%">
2584 <pre class="SCREEN">
2585 +filter{jumping-windows} # Prevent windows from resizing and moving themselves.
2591 <p><a name="FILTER-FRAMESET-BORDERS" id=
2592 "FILTER-FRAMESET-BORDERS"></a></p>
2594 <table border="0" bgcolor="#E0E0E0" width="90%">
2597 <pre class="SCREEN">
2598 +filter{frameset-borders} # Give frames a border and make them resizable.
2604 <p><a name="FILTER-IFRAMES" id="FILTER-IFRAMES"></a></p>
2606 <table border="0" bgcolor="#E0E0E0" width="90%">
2609 <pre class="SCREEN">
2610 +filter{iframes} # Removes all detected iframes. Should only be enabled for individual sites.
2616 <p><a name="FILTER-DEMORONIZER" id=
2617 "FILTER-DEMORONIZER"></a></p>
2619 <table border="0" bgcolor="#E0E0E0" width="90%">
2622 <pre class="SCREEN">
2623 +filter{demoronizer} # Fix MS's non-standard use of standard charsets.
2629 <p><a name="FILTER-SHOCKWAVE-FLASH" id=
2630 "FILTER-SHOCKWAVE-FLASH"></a></p>
2632 <table border="0" bgcolor="#E0E0E0" width="90%">
2635 <pre class="SCREEN">
2636 +filter{shockwave-flash} # Kill embedded Shockwave Flash objects.
2642 <p><a name="FILTER-QUICKTIME-KIOSKMODE" id=
2643 "FILTER-QUICKTIME-KIOSKMODE"></a></p>
2645 <table border="0" bgcolor="#E0E0E0" width="90%">
2648 <pre class="SCREEN">
2649 +filter{quicktime-kioskmode} # Make Quicktime movies saveable.
2655 <p><a name="FILTER-FUN" id="FILTER-FUN"></a></p>
2657 <table border="0" bgcolor="#E0E0E0" width="90%">
2660 <pre class="SCREEN">
2661 +filter{fun} # Text replacements for subversive browsing fun!
2667 <p><a name="FILTER-CRUDE-PARENTAL" id=
2668 "FILTER-CRUDE-PARENTAL"></a></p>
2670 <table border="0" bgcolor="#E0E0E0" width="90%">
2673 <pre class="SCREEN">
2674 +filter{crude-parental} # Crude parental filtering. Note that this filter doesn't work reliably.
2680 <p><a name="FILTER-IE-EXPLOITS" id=
2681 "FILTER-IE-EXPLOITS"></a></p>
2683 <table border="0" bgcolor="#E0E0E0" width="90%">
2686 <pre class="SCREEN">
2687 +filter{ie-exploits} # Disable some known Internet Explorer bug exploits.
2693 <p><a name="FILTER-SITE-SPECIFICS" id=
2694 "FILTER-SITE-SPECIFICS"></a></p>
2696 <table border="0" bgcolor="#E0E0E0" width="90%">
2699 <pre class="SCREEN">
2700 +filter{site-specifics} # Cure for site-specific problems. Don't apply generally!
2706 <p><a name="FILTER-NO-PING" id="FILTER-NO-PING"></a></p>
2708 <table border="0" bgcolor="#E0E0E0" width="90%">
2711 <pre class="SCREEN">
2712 +filter{no-ping} # Removes non-standard ping attributes in <a> and <area> tags.
2718 <p><a name="FILTER-GOOGLE" id="FILTER-GOOGLE"></a></p>
2720 <table border="0" bgcolor="#E0E0E0" width="90%">
2723 <pre class="SCREEN">
2724 +filter{google} # CSS-based block for Google text ads. Also removes a width limitation and the toolbar advertisement.
2730 <p><a name="FILTER-YAHOO" id="FILTER-YAHOO"></a></p>
2732 <table border="0" bgcolor="#E0E0E0" width="90%">
2735 <pre class="SCREEN">
2736 +filter{yahoo} # CSS-based block for Yahoo text ads. Also removes a width limitation.
2742 <p><a name="FILTER-MSN" id="FILTER-MSN"></a></p>
2744 <table border="0" bgcolor="#E0E0E0" width="90%">
2747 <pre class="SCREEN">
2748 +filter{msn} # CSS-based block for MSN text ads. Also removes tracking URLs and a width limitation.
2754 <p><a name="FILTER-BLOGSPOT" id="FILTER-BLOGSPOT"></a></p>
2756 <table border="0" bgcolor="#E0E0E0" width="90%">
2759 <pre class="SCREEN">
2760 +filter{blogspot} # Cleans up some Blogspot blogs. Read the fine print before using this.
2771 <h4 class="SECT3"><a name="FORCE-TEXT-MODE" id=
2772 "FORCE-TEXT-MODE">8.5.17. force-text-mode</a></h4>
2774 <div class="VARIABLELIST">
2776 <dt>Typical use:</dt>
2779 <p>Force <span class="APPLICATION">Privoxy</span> to treat a
2780 document as if it was in some kind of <span class=
2781 "emphasis"><i class="EMPHASIS">text</i></span> format.</p>
2787 <p>Declares a document as text, even if the <span class=
2788 "QUOTE">"Content-Type:"</span> isn't detected as such.</p>
2806 <p>As explained <tt class="LITERAL"><a href=
2807 "actions-file.html#FILTER">above</a></tt>, <span class=
2808 "APPLICATION">Privoxy</span> tries to only filter files that
2809 are in some kind of text format. The same restrictions apply to
2810 <tt class="LITERAL"><a href=
2811 "actions-file.html#CONTENT-TYPE-OVERWRITE">content-type-overwrite</a></tt>.
2812 <tt class="LITERAL">force-text-mode</tt> declares a document as
2813 text, without looking at the <span class=
2814 "QUOTE">"Content-Type:"</span> first.</p>
2816 <div class="WARNING">
2817 <table class="WARNING" border="1" width="90%">
2819 <td align="center"><b>Warning</b></td>
2824 <p>Think twice before activating this action. Filtering
2825 binary data with regular expressions can cause file
2833 <dt>Example usage:</dt>
2836 <table border="0" bgcolor="#E0E0E0" width="90%">
2839 <pre class="SCREEN">
2852 <h4 class="SECT3"><a name="FORWARD-OVERRIDE" id=
2853 "FORWARD-OVERRIDE">8.5.18. forward-override</a></h4>
2855 <div class="VARIABLELIST">
2857 <dt>Typical use:</dt>
2860 <p>Change the forwarding settings based on User-Agent or
2867 <p>Overrules the forward directives in the configuration
2874 <p>Parameterized.</p>
2882 <p><span class="QUOTE">"forward ."</span> to use a direct
2883 connection without any additional proxies.</p>
2887 <p><span class="QUOTE">"forward 127.0.0.1:8123"</span> to
2888 use the HTTP proxy listening at 127.0.0.1 port 8123.</p>
2892 <p><span class="QUOTE">"forward-socks4a 127.0.0.1:9050
2893 ."</span> to use the socks4a proxy listening at 127.0.0.1
2894 port 9050. Replace <span class=
2895 "QUOTE">"forward-socks4a"</span> with <span class=
2896 "QUOTE">"forward-socks4"</span> to use a socks4 connection
2897 (with local DNS resolution) instead, use <span class=
2898 "QUOTE">"forward-socks5"</span> for socks5 connections
2899 (with remote DNS resolution).</p>
2903 <p><span class="QUOTE">"forward-socks4a 127.0.0.1:9050
2904 proxy.example.org:8000"</span> to use the socks4a proxy
2905 listening at 127.0.0.1 port 9050 to reach the HTTP proxy
2906 listening at proxy.example.org port 8000. Replace
2907 <span class="QUOTE">"forward-socks4a"</span> with
2908 <span class="QUOTE">"forward-socks4"</span> to use a socks4
2909 connection (with local DNS resolution) instead, use
2910 <span class="QUOTE">"forward-socks5"</span> for socks5
2911 connections (with remote DNS resolution).</p>
2915 <p><span class="QUOTE">"forward-webserver
2916 127.0.0.1:80"</span> to use the HTTP server listening at
2917 127.0.0.1 port 80 without adjusting the request
2920 <p>This makes it more convenient to use Privoxy to make
2921 existing websites available as onion services as well.</p>
2923 <p>Many websites serve content with hardcoded URLs and
2924 can't be easily adjusted to change the domain based on the
2925 one used by the client.</p>
2927 <p>Putting Privoxy between Tor and the webserver (or an
2928 stunnel that forwards to the webserver) allows to rewrite
2929 headers and content to make client and server happy at the
2932 <p>Using Privoxy for webservers that are only reachable
2933 through onion addresses and whose location is supposed to
2934 be secret is not recommended and should not be necessary
2943 <p>This action takes parameters similar to the <a href=
2944 "config.html#FORWARDING">forward</a> directives in the
2945 configuration file, but without the URL pattern. It can be used
2946 as replacement, but normally it's only used in cases where
2947 matching based on the request URL isn't sufficient.</p>
2949 <div class="WARNING">
2950 <table class="WARNING" border="1" width="90%">
2952 <td align="center"><b>Warning</b></td>
2957 <p>Please read the description for the <a href=
2958 "config.html#FORWARDING">forward</a> directives before
2959 using this action. Forwarding to the wrong people will
2960 reduce your privacy and increase the chances of
2961 man-in-the-middle attacks.</p>
2963 <p>If the ports are missing or invalid, default values
2964 will be used. This might change in the future and you
2965 shouldn't rely on it. Otherwise incorrect syntax causes
2966 Privoxy to exit. Due to design limitations, invalid
2967 parameter syntax isn't detected until the action is
2968 used the first time.</p>
2971 "http://config.privoxy.org/show-url-info" target=
2972 "_top">show-url-info CGI page</a> to verify that your
2973 forward settings do what you thought the do.</p>
2980 <dt>Example usage:</dt>
2983 <table border="0" bgcolor="#E0E0E0" width="90%">
2986 <pre class="SCREEN">
2987 # Use an ssh tunnel for requests previously tagged as
2988 # <span class="QUOTE">"User-Agent: fetch libfetch/2.0"</span> and make sure
2989 # resuming downloads continues to work.
2991 # This way you can continue to use Tor for your normal browsing,
2992 # without overloading the Tor network with your FreeBSD ports updates
2993 # or downloads of bigger files like ISOs.
2995 # Note that HTTP headers are easy to fake and therefore their
2996 # values are as (un)trustworthy as your clients and users.
2997 {+forward-override{forward-socks5 10.0.0.2:2222 .} \
2998 -hide-if-modified-since \
2999 -overwrite-last-modified \
3001 TAG:^User-Agent: fetch libfetch/2\.0$
3013 <h4 class="SECT3"><a name="HANDLE-AS-EMPTY-DOCUMENT" id=
3014 "HANDLE-AS-EMPTY-DOCUMENT">8.5.19. handle-as-empty-document</a></h4>
3016 <div class="VARIABLELIST">
3018 <dt>Typical use:</dt>
3021 <p>Mark URLs that should be replaced by empty documents
3022 <span class="emphasis"><i class="EMPHASIS">if they get
3023 blocked</i></span></p>
3029 <p>This action alone doesn't do anything noticeable. It just
3030 marks URLs. If the <tt class="LITERAL"><a href=
3031 "actions-file.html#BLOCK">block</a></tt> action <span class=
3032 "emphasis"><i class="EMPHASIS">also applies</i></span>, the
3033 presence or absence of this mark decides whether an HTML
3034 <span class="QUOTE">"BLOCKED"</span> page, or an empty document
3035 will be sent to the client as a substitute for the blocked
3036 content. The <span class="emphasis"><i class=
3037 "EMPHASIS">empty</i></span> document isn't literally empty, but
3038 actually contains a single space.</p>
3056 <p>Some browsers complain about syntax errors if JavaScript
3057 documents are blocked with <span class=
3058 "APPLICATION">Privoxy's</span> default HTML page; this option
3059 can be used to silence them. And of course this action can also
3060 be used to eliminate the <span class=
3061 "APPLICATION">Privoxy</span> BLOCKED message in frames.</p>
3063 <p>The content type for the empty document can be specified
3064 with <tt class="LITERAL"><a href=
3065 "actions-file.html#CONTENT-TYPE-OVERWRITE">content-type-overwrite{}</a></tt>,
3066 but usually this isn't necessary.</p>
3069 <dt>Example usage:</dt>
3072 <table border="0" bgcolor="#E0E0E0" width="90%">
3075 <pre class="SCREEN">
3076 # Block all documents on example.org that end with ".js",
3077 # but send an empty document instead of the usual HTML message.
3078 {+block{Blocked JavaScript} +handle-as-empty-document}
3091 <h4 class="SECT3"><a name="HANDLE-AS-IMAGE" id=
3092 "HANDLE-AS-IMAGE">8.5.20. handle-as-image</a></h4>
3094 <div class="VARIABLELIST">
3096 <dt>Typical use:</dt>
3099 <p>Mark URLs as belonging to images (so they'll be replaced by
3100 images <span class="emphasis"><i class="EMPHASIS">if they do
3101 get blocked</i></span>, rather than HTML pages)</p>
3107 <p>This action alone doesn't do anything noticeable. It just
3108 marks URLs as images. If the <tt class="LITERAL"><a href=
3109 "actions-file.html#BLOCK">block</a></tt> action <span class=
3110 "emphasis"><i class="EMPHASIS">also applies</i></span>, the
3111 presence or absence of this mark decides whether an HTML
3112 <span class="QUOTE">"blocked"</span> page, or a replacement
3113 image (as determined by the <tt class="LITERAL"><a href=
3114 "actions-file.html#SET-IMAGE-BLOCKER">set-image-blocker</a></tt>
3115 action) will be sent to the client as a substitute for the
3116 blocked content.</p>
3134 <p>The below generic example section is actually part of
3135 <tt class="FILENAME">default.action</tt>. It marks all URLs
3136 with well-known image file name extensions as images and should
3139 <p>Users will probably only want to use the handle-as-image
3140 action in conjunction with <tt class="LITERAL"><a href=
3141 "actions-file.html#BLOCK">block</a></tt>, to block sources of
3142 banners, whose URLs don't reflect the file type, like in the
3143 second example section.</p>
3145 <p>Note that you cannot treat HTML pages as images in most
3146 cases. For instance, (in-line) ad frames require an HTML page
3147 to be sent, or they won't display properly. Forcing <tt class=
3148 "LITERAL">handle-as-image</tt> in this situation will not
3149 replace the ad frame with an image, but lead to error
3153 <dt>Example usage (sections):</dt>
3156 <table border="0" bgcolor="#E0E0E0" width="90%">
3159 <pre class="SCREEN">
3160 # Generic image extensions:
3163 /.*\.(gif|jpg|jpeg|png|bmp|ico)$
3165 # These don't look like images, but they're banners and should be
3166 # blocked as images:
3168 {+block{Nasty banners.} +handle-as-image}
3169 nasty-banner-server.example.com/junk.cgi\?output=trash
3180 <h4 class="SECT3"><a name="HIDE-ACCEPT-LANGUAGE" id=
3181 "HIDE-ACCEPT-LANGUAGE">8.5.21. hide-accept-language</a></h4>
3183 <div class="VARIABLELIST">
3185 <dt>Typical use:</dt>
3188 <p>Pretend to use different language settings.</p>
3194 <p>Deletes or replaces the <span class=
3195 "QUOTE">"Accept-Language:"</span> HTTP header in client
3202 <p>Parameterized.</p>
3208 <p>Keyword: <span class="QUOTE">"block"</span>, or any user
3215 <p>Faking the browser's language settings can be useful to make
3216 a foreign User-Agent set with <tt class="LITERAL"><a href=
3217 "actions-file.html#HIDE-USER-AGENT">hide-user-agent</a></tt>
3218 more believable.</p>
3220 <p>However some sites with content in different languages check
3221 the <span class="QUOTE">"Accept-Language:"</span> to decide
3222 which one to take by default. Sometimes it isn't possible to
3223 later switch to another language without changing the
3224 <span class="QUOTE">"Accept-Language:"</span> header first.</p>
3226 <p>Therefore it's a good idea to either only change the
3227 <span class="QUOTE">"Accept-Language:"</span> header to
3228 languages you understand, or to languages that aren't wide
3231 <p>Before setting the <span class=
3232 "QUOTE">"Accept-Language:"</span> header to a rare language,
3233 you should consider that it helps to make your requests unique
3234 and thus easier to trace. If you don't plan to change this
3235 header frequently, you should stick to a common language.</p>
3238 <dt>Example usage (section):</dt>
3241 <table border="0" bgcolor="#E0E0E0" width="90%">
3244 <pre class="SCREEN">
3245 # Pretend to use Canadian language settings.
3246 {+hide-accept-language{en-ca} \
3247 +hide-user-agent{Mozilla/5.0 (X11; U; OpenBSD i386; en-CA; rv:1.8.0.4) Gecko/20060628 Firefox/1.5.0.4} \
3260 <h4 class="SECT3"><a name="HIDE-CONTENT-DISPOSITION" id=
3261 "HIDE-CONTENT-DISPOSITION">8.5.22. hide-content-disposition</a></h4>
3263 <div class="VARIABLELIST">
3265 <dt>Typical use:</dt>
3268 <p>Prevent download menus for content you prefer to view inside
3275 <p>Deletes or replaces the <span class=
3276 "QUOTE">"Content-Disposition:"</span> HTTP header set by some
3283 <p>Parameterized.</p>
3289 <p>Keyword: <span class="QUOTE">"block"</span>, or any user
3296 <p>Some servers set the <span class=
3297 "QUOTE">"Content-Disposition:"</span> HTTP header for documents
3298 they assume you want to save locally before viewing them. The
3299 <span class="QUOTE">"Content-Disposition:"</span> header
3300 contains the file name the browser is supposed to use by
3303 <p>In most browsers that understand this header, it makes it
3304 impossible to <span class="emphasis"><i class="EMPHASIS">just
3305 view</i></span> the document, without downloading it first,
3306 even if it's just a simple text file or an image.</p>
3308 <p>Removing the <span class=
3309 "QUOTE">"Content-Disposition:"</span> header helps to prevent
3310 this annoyance, but some browsers additionally check the
3311 <span class="QUOTE">"Content-Type:"</span> header, before they
3312 decide if they can display a document without saving it first.
3313 In these cases, you have to change this header as well, before
3314 the browser stops displaying download menus.</p>
3316 <p>It is also possible to change the server's file name
3317 suggestion to another one, but in most cases it isn't worth the
3318 time to set it up.</p>
3320 <p>This action will probably be removed in the future, use
3321 server-header filters instead.</p>
3324 <dt>Example usage:</dt>
3327 <table border="0" bgcolor="#E0E0E0" width="90%">
3330 <pre class="SCREEN">
3331 # Disarm the download link in Sourceforge's patch tracker
3333 +content-type-overwrite{text/plain}\
3334 +hide-content-disposition{block} }
3335 .sourceforge.net/tracker/download\.php
3346 <h4 class="SECT3"><a name="HIDE-IF-MODIFIED-SINCE" id=
3347 "HIDE-IF-MODIFIED-SINCE">8.5.23. hide-if-modified-since</a></h4>
3349 <div class="VARIABLELIST">
3351 <dt>Typical use:</dt>
3354 <p>Prevent yet another way to track the user's steps between
3361 <p>Deletes the <span class="QUOTE">"If-Modified-Since:"</span>
3362 HTTP client header or modifies its value.</p>
3368 <p>Parameterized.</p>
3374 <p>Keyword: <span class="QUOTE">"block"</span>, or a user
3375 defined value that specifies a range of hours.</p>
3381 <p>Removing this header is useful for filter testing, where you
3382 want to force a real reload instead of getting status code
3383 <span class="QUOTE">"304"</span>, which would cause the browser
3384 to use a cached copy of the page.</p>
3386 <p>Instead of removing the header, <tt class=
3387 "LITERAL">hide-if-modified-since</tt> can also add or subtract
3388 a random amount of time to/from the header's value. You specify
3389 a range of minutes where the random factor should be chosen
3390 from and <span class="APPLICATION">Privoxy</span> does the
3391 rest. A negative value means subtracting, a positive value
3394 <p>Randomizing the value of the <span class=
3395 "QUOTE">"If-Modified-Since:"</span> makes it less likely that
3396 the server can use the time as a cookie replacement, but you
3397 will run into caching problems if the random range is too
3400 <p>It is a good idea to only use a small negative value and let
3401 <tt class="LITERAL"><a href=
3402 "actions-file.html#OVERWRITE-LAST-MODIFIED">overwrite-last-modified</a></tt>
3403 handle the greater changes.</p>
3405 <p>It is also recommended to use this action together with
3406 <tt class="LITERAL"><a href=
3407 "actions-file.html#CRUNCH-IF-NONE-MATCH">crunch-if-none-match</a></tt>,
3408 otherwise it's more or less pointless.</p>
3411 <dt>Example usage (section):</dt>
3414 <table border="0" bgcolor="#E0E0E0" width="90%">
3417 <pre class="SCREEN">
3418 # Let the browser revalidate but make tracking based on the time less likely.
3419 {+hide-if-modified-since{-60} \
3420 +overwrite-last-modified{randomize} \
3421 +crunch-if-none-match}
3433 <h4 class="SECT3"><a name="HIDE-FROM-HEADER" id=
3434 "HIDE-FROM-HEADER">8.5.24. hide-from-header</a></h4>
3436 <div class="VARIABLELIST">
3438 <dt>Typical use:</dt>
3441 <p>Keep your (old and ill) browser from telling web servers
3442 your email address</p>
3448 <p>Deletes any existing <span class="QUOTE">"From:"</span> HTTP
3449 header, or replaces it with the specified string.</p>
3455 <p>Parameterized.</p>
3461 <p>Keyword: <span class="QUOTE">"block"</span>, or any user
3468 <p>The keyword <span class="QUOTE">"block"</span> will
3469 completely remove the header (not to be confused with the
3470 <tt class="LITERAL"><a href=
3471 "actions-file.html#BLOCK">block</a></tt> action).</p>
3473 <p>Alternately, you can specify any value you prefer to be sent
3474 to the web server. If you do, it is a matter of fairness not to
3475 use any address that is actually used by a real person.</p>
3477 <p>This action is rarely needed, as modern web browsers don't
3478 send <span class="QUOTE">"From:"</span> headers anymore.</p>
3481 <dt>Example usage:</dt>
3484 <table border="0" bgcolor="#E0E0E0" width="90%">
3487 <pre class="SCREEN">
3488 +hide-from-header{block}
3494 <table border="0" bgcolor="#E0E0E0" width="90%">
3497 <pre class="SCREEN">
3498 +hide-from-header{spam-me-senseless@sittingduck.example.com}
3509 <h4 class="SECT3"><a name="HIDE-REFERRER" id="HIDE-REFERRER">8.5.25.
3510 hide-referrer</a></h4><a name="HIDE-REFERER" id="HIDE-REFERER"></a>
3512 <div class="VARIABLELIST">
3514 <dt>Typical use:</dt>
3517 <p>Conceal which link you followed to get to a particular
3524 <p>Deletes the <span class="QUOTE">"Referer:"</span> (sic) HTTP
3525 header from the client request, or replaces it with a forged
3532 <p>Parameterized.</p>
3540 <p><span class="QUOTE">"conditional-block"</span> to delete
3541 the header completely if the host has changed.</p>
3545 <p><span class="QUOTE">"conditional-forge"</span> to forge
3546 the header if the host has changed.</p>
3550 <p><span class="QUOTE">"block"</span> to delete the header
3551 unconditionally.</p>
3555 <p><span class="QUOTE">"forge"</span> to pretend to be
3556 coming from the homepage of the server we are talking
3561 <p>Any other string to set a user defined referrer.</p>
3569 <p><tt class="LITERAL">conditional-block</tt> is the only
3570 parameter, that isn't easily detected in the server's log file.
3571 If it blocks the referrer, the request will look like the
3572 visitor used a bookmark or typed in the address directly.</p>
3574 <p>Leaving the referrer unmodified for requests on the same
3575 host allows the server owner to see the visitor's <span class=
3576 "QUOTE">"click path"</span>, but in most cases she could also
3577 get that information by comparing other parts of the log file:
3578 for example the User-Agent if it isn't a very common one, or
3579 the user's IP address if it doesn't change between different
3582 <p>Always blocking the referrer, or using a custom one, can
3583 lead to failures on servers that check the referrer before they
3584 answer any requests, in an attempt to prevent their content
3585 from being embedded or linked to elsewhere.</p>
3587 <p>Both <tt class="LITERAL">conditional-block</tt> and
3588 <tt class="LITERAL">forge</tt> will work with referrer checks,
3589 as long as content and valid referring page are on the same
3590 host. Most of the time that's the case.</p>
3592 <p><tt class="LITERAL">hide-referer</tt> is an alternate
3593 spelling of <tt class="LITERAL">hide-referrer</tt> and the two
3594 can be can be freely substituted with each other. (<span class=
3595 "QUOTE">"referrer"</span> is the correct English spelling,
3596 however the HTTP specification has a bug - it requires it to be
3597 spelled as <span class="QUOTE">"referer"</span>.)</p>
3600 <dt>Example usage:</dt>
3603 <table border="0" bgcolor="#E0E0E0" width="90%">
3606 <pre class="SCREEN">
3607 +hide-referrer{forge}
3613 <table border="0" bgcolor="#E0E0E0" width="90%">
3616 <pre class="SCREEN">
3617 +hide-referrer{http://www.yahoo.com/}
3628 <h4 class="SECT3"><a name="HIDE-USER-AGENT" id=
3629 "HIDE-USER-AGENT">8.5.26. hide-user-agent</a></h4>
3631 <div class="VARIABLELIST">
3633 <dt>Typical use:</dt>
3636 <p>Try to conceal your type of browser and client operating
3643 <p>Replaces the value of the <span class=
3644 "QUOTE">"User-Agent:"</span> HTTP header in client requests
3645 with the specified value.</p>
3651 <p>Parameterized.</p>
3657 <p>Any user-defined string.</p>
3663 <div class="WARNING">
3664 <table class="WARNING" border="1" width="90%">
3666 <td align="center"><b>Warning</b></td>
3671 <p>This can lead to problems on web sites that depend
3672 on looking at this header in order to customize their
3673 content for different browsers (which, by the way, is
3674 <span class="emphasis"><i class=
3675 "EMPHASIS">NOT</i></span> the right thing to do: good
3676 web sites work browser-independently).</p>
3682 <p>Using this action in multi-user setups or wherever different
3683 types of browsers will access the same <span class=
3684 "APPLICATION">Privoxy</span> is <span class=
3685 "emphasis"><i class="EMPHASIS">not recommended</i></span>. In
3686 single-user, single-browser setups, you might use it to delete
3687 your OS version information from the headers, because it is an
3688 invitation to exploit known bugs for your OS. It is also
3689 occasionally useful to forge this in order to access sites that
3690 won't let you in otherwise (though there may be a good reason
3693 <p>More information on known user-agent strings can be found at
3694 <a href="http://www.user-agents.org/" target=
3695 "_top">http://www.user-agents.org/</a> and <a href=
3696 "http://en.wikipedia.org/wiki/User_agent" target=
3697 "_top">http://en.wikipedia.org/wiki/User_agent</a>.</p>
3700 <dt>Example usage:</dt>
3703 <table border="0" bgcolor="#E0E0E0" width="90%">
3706 <pre class="SCREEN">
3707 +hide-user-agent{Netscape 6.1 (X11; I; Linux 2.4.18 i686)}
3718 <h4 class="SECT3"><a name="LIMIT-CONNECT" id="LIMIT-CONNECT">8.5.27.
3719 limit-connect</a></h4>
3721 <div class="VARIABLELIST">
3723 <dt>Typical use:</dt>
3726 <p>Prevent abuse of <span class="APPLICATION">Privoxy</span> as
3727 a TCP proxy relay or disable SSL for untrusted sites</p>
3733 <p>Specifies to which ports HTTP CONNECT requests are
3740 <p>Parameterized.</p>
3746 <p>A comma-separated list of ports or port ranges (the latter
3747 using dashes, with the minimum defaulting to 0 and the maximum
3754 <p>By default, i.e. if no <tt class=
3755 "LITERAL">limit-connect</tt> action applies, <span class=
3756 "APPLICATION">Privoxy</span> allows HTTP CONNECT requests to
3757 all ports. Use <tt class="LITERAL">limit-connect</tt> if
3758 fine-grained control is desired for some or all
3761 <p>The CONNECT methods exists in HTTP to allow access to secure
3762 websites (<span class="QUOTE">"https://"</span> URLs) through
3763 proxies. It works very simply: the proxy connects to the server
3764 on the specified port, and then short-circuits its connections
3765 to the client and to the remote server. This means
3766 CONNECT-enabled proxies can be used as TCP relays very
3769 <p><span class="APPLICATION">Privoxy</span> relays HTTPS
3770 traffic without seeing the decoded content. Websites can
3771 leverage this limitation to circumvent <span class=
3772 "APPLICATION">Privoxy</span>'s filters. By specifying an
3773 invalid port range you can disable HTTPS entirely.</p>
3776 <dt>Example usages:</dt>
3779 <table border="0" bgcolor="#E0E0E0" width="90%">
3782 <pre class="SCREEN">
3783 +limit-connect{443} # Port 443 is OK.
3784 +limit-connect{80,443} # Ports 80 and 443 are OK.
3785 +limit-connect{-3, 7, 20-100, 500-} # Ports less than 3, 7, 20 to 100 and above 500 are OK.
3786 +limit-connect{-} # All ports are OK
3787 +limit-connect{,} # No HTTPS/SSL traffic is allowed
3798 <h4 class="SECT3"><a name="LIMIT-COOKIE-LIFETIME" id=
3799 "LIMIT-COOKIE-LIFETIME">8.5.28. limit-cookie-lifetime</a></h4>
3801 <div class="VARIABLELIST">
3803 <dt>Typical use:</dt>
3806 <p>Limit the lifetime of HTTP cookies to a couple of minutes or
3813 <p>Overwrites the expires field in Set-Cookie server headers if
3814 it's above the specified limit.</p>
3820 <p>Parameterized.</p>
3826 <p>The lifetime limit in minutes, or 0.</p>
3832 <p>This action reduces the lifetime of HTTP cookies coming from
3833 the server to the specified number of minutes, starting from
3834 the time the cookie passes Privoxy.</p>
3836 <p>Cookies with a lifetime below the limit are not modified.
3837 The lifetime of session cookies is set to the specified
3840 <p>The effect of this action depends on the server.</p>
3842 <p>In case of servers which refresh their cookies with each
3843 response (or at least frequently), the lifetime limit set by
3844 this action is updated as well. Thus, a session associated with
3845 the cookie continues to work with this action enabled, as long
3846 as a new request is made before the last limit set is
3849 <p>However, some servers send their cookies once, with a
3850 lifetime of several years (the year 2037 is a popular choice),
3851 and do not refresh them until a certain event in the future,
3852 for example the user logging out. In this case this action may
3853 limit the absolute lifetime of the session, even if requests
3854 are made frequently.</p>
3856 <p>If the parameter is <span class="QUOTE">"0"</span>, this
3857 action behaves like <tt class="LITERAL"><a href=
3858 "actions-file.html#SESSION-COOKIES-ONLY">session-cookies-only</a></tt>.</p>
3861 <dt>Example usages:</dt>
3864 <table border="0" bgcolor="#E0E0E0" width="90%">
3867 <pre class="SCREEN">
3868 +limit-cookie-lifetime{60}
3880 <h4 class="SECT3"><a name="PREVENT-COMPRESSION" id=
3881 "PREVENT-COMPRESSION">8.5.29. prevent-compression</a></h4>
3883 <div class="VARIABLELIST">
3885 <dt>Typical use:</dt>
3888 <p>Ensure that servers send the content uncompressed, so it can
3889 be passed through <tt class="LITERAL"><a href=
3890 "actions-file.html#FILTER">filter</a></tt>s.</p>
3896 <p>Removes the Accept-Encoding header which can be used to ask
3897 for compressed transfer.</p>
3915 <p>More and more websites send their content compressed by
3916 default, which is generally a good idea and saves bandwidth.
3917 But the <tt class="LITERAL"><a href=
3918 "actions-file.html#FILTER">filter</a></tt> and <tt class=
3920 "actions-file.html#DEANIMATE-GIFS">deanimate-gifs</a></tt>
3921 actions need access to the uncompressed data.</p>
3923 <p>When compiled with zlib support (available since
3924 <span class="APPLICATION">Privoxy</span> 3.0.7), content that
3925 should be filtered is decompressed on-the-fly and you don't
3926 have to worry about this action. If you are using an older
3927 <span class="APPLICATION">Privoxy</span> version, or one that
3928 hasn't been compiled with zlib support, this action can be used
3929 to convince the server to send the content uncompressed.</p>
3931 <p>Most text-based instances compress very well, the size is
3932 seldom decreased by less than 50%, for markup-heavy instances
3933 like news feeds saving more than 90% of the original size isn't
3936 <p>Not using compression will therefore slow down the transfer,
3937 and you should only enable this action if you really need it.
3938 As of <span class="APPLICATION">Privoxy</span> 3.0.7 it's
3939 disabled in all predefined action settings.</p>
3941 <p>Note that some (rare) ill-configured sites don't handle
3942 requests for uncompressed documents correctly. Broken PHP
3943 applications tend to send an empty document body, some IIS
3944 versions only send the beginning of the content. If you enable
3945 <tt class="LITERAL">prevent-compression</tt> per default, you
3946 might want to add exceptions for those sites. See the example
3947 for how to do that.</p>
3950 <dt>Example usage (sections):</dt>
3953 <table border="0" bgcolor="#E0E0E0" width="90%">
3956 <pre class="SCREEN">
3957 # Selectively turn off compression, and enable a filter
3959 { +filter{tiny-textforms} +prevent-compression }
3960 # Match only these sites
3965 # Or instead, we could set a universal default:
3967 { +prevent-compression }
3970 # Then maybe make exceptions for broken sites:
3972 { -prevent-compression }
3984 <h4 class="SECT3"><a name="OVERWRITE-LAST-MODIFIED" id=
3985 "OVERWRITE-LAST-MODIFIED">8.5.30. overwrite-last-modified</a></h4>
3987 <div class="VARIABLELIST">
3989 <dt>Typical use:</dt>
3992 <p>Prevent yet another way to track the user's steps between
3999 <p>Deletes the <span class="QUOTE">"Last-Modified:"</span> HTTP
4000 server header or modifies its value.</p>
4006 <p>Parameterized.</p>
4012 <p>One of the keywords: <span class="QUOTE">"block"</span>,
4013 <span class="QUOTE">"reset-to-request-time"</span> and
4014 <span class="QUOTE">"randomize"</span></p>
4020 <p>Removing the <span class="QUOTE">"Last-Modified:"</span>
4021 header is useful for filter testing, where you want to force a
4022 real reload instead of getting status code <span class=
4023 "QUOTE">"304"</span>, which would cause the browser to reuse
4024 the old version of the page.</p>
4026 <p>The <span class="QUOTE">"randomize"</span> option overwrites
4027 the value of the <span class="QUOTE">"Last-Modified:"</span>
4028 header with a randomly chosen time between the original value
4029 and the current time. In theory the server could send each
4030 document with a different <span class=
4031 "QUOTE">"Last-Modified:"</span> header to track visits without
4032 using cookies. <span class="QUOTE">"Randomize"</span> makes it
4033 impossible and the browser can still revalidate cached
4036 <p><span class="QUOTE">"reset-to-request-time"</span>
4037 overwrites the value of the <span class=
4038 "QUOTE">"Last-Modified:"</span> header with the current time.
4039 You could use this option together with <tt class=
4041 "actions-file.html#HIDE-IF-MODIFIED-SINCE">hide-if-modified-since</a></tt>
4042 to further customize your random range.</p>
4044 <p>The preferred parameter here is <span class=
4045 "QUOTE">"randomize"</span>. It is safe to use, as long as the
4046 time settings are more or less correct. If the server sets the
4047 <span class="QUOTE">"Last-Modified:"</span> header to the time
4048 of the request, the random range becomes zero and the value
4049 stays the same. Therefore you should later randomize it a
4050 second time with <tt class="LITERAL"><a href=
4051 "actions-file.html#HIDE-IF-MODIFIED-SINCE">hided-if-modified-since</a></tt>,
4052 just to be sure.</p>
4054 <p>It is also recommended to use this action together with
4055 <tt class="LITERAL"><a href=
4056 "actions-file.html#CRUNCH-IF-NONE-MATCH">crunch-if-none-match</a></tt>.</p>
4059 <dt>Example usage:</dt>
4062 <table border="0" bgcolor="#E0E0E0" width="90%">
4065 <pre class="SCREEN">
4066 # Let the browser revalidate without being tracked across sessions
4067 { +hide-if-modified-since{-60} \
4068 +overwrite-last-modified{randomize} \
4069 +crunch-if-none-match}
4081 <h4 class="SECT3"><a name="REDIRECT" id="REDIRECT">8.5.31.
4084 <div class="VARIABLELIST">
4086 <dt>Typical use:</dt>
4089 <p>Redirect requests to other sites.</p>
4095 <p>Convinces the browser that the requested document has been
4096 moved to another location and the browser should get it from
4103 <p>Parameterized</p>
4109 <p>An absolute URL or a single pcrs command.</p>
4115 <p>Requests to which this action applies are answered with a
4116 HTTP redirect to URLs of your choosing. The new URL is either
4117 provided as parameter, or derived by applying a single pcrs
4118 command to the original URL.</p>
4120 <p>The syntax for pcrs commands is documented in the <a href=
4121 "filter-file.html">filter file</a> section.</p>
4123 <p>Requests can't be blocked and redirected at the same time,
4124 applying this action together with <tt class="LITERAL"><a href=
4125 "actions-file.html#BLOCK">block</a></tt> is a configuration
4126 error. Currently the request is blocked and an error message
4127 logged, the behavior may change in the future and result in
4128 Privoxy rejecting the action file.</p>
4130 <p>This action can be combined with <tt class=
4131 "LITERAL"><a href="actions-file.html#FAST-REDIRECTS">fast-redirects{check-decoded-url}</a></tt>
4132 to redirect to a decoded version of a rewritten URL.</p>
4134 <p>Use this action carefully, make sure not to create
4135 redirection loops and be aware that using your own redirects
4136 might make it possible to fingerprint your requests.</p>
4138 <p>In case of problems with your redirects, or simply to watch
4139 them working, enable <a href="config.html#DEBUG">debug
4143 <dt>Example usages:</dt>
4146 <table border="0" bgcolor="#E0E0E0" width="90%">
4149 <pre class="SCREEN">
4150 # Replace example.com's style sheet with another one
4151 { +redirect{http://localhost/css-replacements/example.com.css} }
4152 example.com/stylesheet\.css
4154 # Create a short, easy to remember nickname for a favorite site
4155 # (relies on the browser to accept and forward invalid URLs to <span class=
4156 "APPLICATION">Privoxy</span>)
4157 { +redirect{https://www.privoxy.org/user-manual/actions-file.html} }
4160 # Always use the expanded view for Undeadly.org articles
4161 # (Note the $ at the end of the URL pattern to make sure
4162 # the request for the rewritten URL isn't redirected as well)
4163 {+redirect{s@$@&mode=expanded@}}
4164 undeadly.org/cgi\?action=article&sid=\d*$
4166 # Redirect Google search requests to MSN
4167 {+redirect{s@^http://[^/]*/search\?q=([^&]*).*@http://search.msn.com/results.aspx?q=$1@}}
4170 # Redirect MSN search requests to Yahoo
4171 {+redirect{s@^http://[^/]*/results\.aspx\?q=([^&]*).*@http://search.yahoo.com/search?p=$1@}}
4172 search.msn.com//results\.aspx\?q=
4174 # Redirect http://example.com/&bla=fasel&toChange=foo (and any other value but "bar")
4175 # to http://example.com/&bla=fasel&toChange=bar
4177 # The URL pattern makes sure that the following request isn't redirected again.
4178 {+redirect{s@toChange=[^&]+@toChange=bar@}}
4179 example.com/.*toChange=(?!bar)
4181 # Add a shortcut to look up illumos bugs
4182 {+redirect{s@^http://i([0-9]+)/.*@https://www.illumos.org/issues/$1@}}
4183 # Redirected URL = http://i4974/
4184 # Redirect Destination = https://www.illumos.org/issues/4974
4185 i[0-9][0-9][0-9][0-9]*/
4187 # Redirect remote requests for this manual
4188 # to the local version delivered by Privoxy
4189 {+redirect{s@^http://www@http://config@}}
4190 www.privoxy.org/user-manual/
4201 <h4 class="SECT3"><a name="SERVER-HEADER-FILTER" id=
4202 "SERVER-HEADER-FILTER">8.5.32. server-header-filter</a></h4>
4204 <div class="VARIABLELIST">
4206 <dt>Typical use:</dt>
4209 <p>Rewrite or remove single server headers.</p>
4215 <p>All server headers to which this action applies are filtered
4216 on-the-fly through the specified regular expression based
4229 <p>The name of a server-header filter, as defined in one of the
4230 <a href="filter-file.html">filter files</a>.</p>
4236 <p>Server-header filters are applied to each header on its own,
4237 not to all at once. This makes it easier to diagnose problems,
4238 but on the downside you can't write filters that only change
4239 header x if header y's value is z. You can do that by using
4242 <p>Server-header filters are executed after the other header
4243 actions have finished and use their output as input.</p>
4245 <p>Please refer to the <a href="filter-file.html">filter file
4246 chapter</a> to learn which server-header filters are available
4247 by default, and how to create your own.</p>
4250 <dt>Example usage (section):</dt>
4253 <table border="0" bgcolor="#E0E0E0" width="90%">
4256 <pre class="SCREEN">
4257 {+server-header-filter{html-to-xml}}
4258 example.org/xml-instance-that-is-delivered-as-html
4260 {+server-header-filter{xml-to-html}}
4261 example.org/instance-that-is-delivered-as-xml-but-is-not
4273 <h4 class="SECT3"><a name="SERVER-HEADER-TAGGER" id=
4274 "SERVER-HEADER-TAGGER">8.5.33. server-header-tagger</a></h4>
4276 <div class="VARIABLELIST">
4278 <dt>Typical use:</dt>
4281 <p>Enable or disable filters based on the Content-Type
4288 <p>Server headers to which this action applies are filtered
4289 on-the-fly through the specified regular expression based
4290 substitutions, the result is used as tag.</p>
4302 <p>The name of a server-header tagger, as defined in one of the
4303 <a href="filter-file.html">filter files</a>.</p>
4309 <p>Server-header taggers are applied to each header on its own,
4310 and as the header isn't modified, each tagger <span class=
4311 "QUOTE">"sees"</span> the original.</p>
4313 <p>Server-header taggers are executed before all other header
4314 actions that modify server headers. Their tags can be used to
4315 control all of the other server-header actions, the content
4316 filters and the crunch actions (<a href=
4317 "actions-file.html#REDIRECT">redirect</a> and <a href=
4318 "actions-file.html#BLOCK">block</a>).</p>
4320 <p>Obviously crunching based on tags created by server-header
4321 taggers doesn't prevent the request from showing up in the
4322 server's log file.</p>
4325 <dt>Example usage (section):</dt>
4328 <table border="0" bgcolor="#E0E0E0" width="90%">
4331 <pre class="SCREEN">
4332 # Tag every request with the content type declared by the server
4333 {+server-header-tagger{content-type}}
4336 # If the response has a tag starting with 'image/' enable an external
4337 # filter that only applies to images.
4339 # Note that the filter is not available by default, it's just a
4340 # <tt class="LITERAL"><a href=
4341 "filter-file.html#EXTERNAL-FILTER-SYNTAX">silly example</a></tt>.
4342 {+external-filter{rotate-image} +force-text-mode}
4355 <h4 class="SECT3"><a name="SESSION-COOKIES-ONLY" id=
4356 "SESSION-COOKIES-ONLY">8.5.34. session-cookies-only</a></h4>
4358 <div class="VARIABLELIST">
4360 <dt>Typical use:</dt>
4363 <p>Allow only temporary <span class="QUOTE">"session"</span>
4364 cookies (for the current browser session <span class=
4365 "emphasis"><i class="EMPHASIS">only</i></span>).</p>
4371 <p>Deletes the <span class="QUOTE">"expires"</span> field from
4372 <span class="QUOTE">"Set-Cookie:"</span> server headers. Most
4373 browsers will not store such cookies permanently and forget
4374 them in between sessions.</p>
4392 <p>This is less strict than <tt class="LITERAL"><a href=
4393 "actions-file.html#CRUNCH-INCOMING-COOKIES">crunch-incoming-cookies</a></tt>
4394 / <tt class="LITERAL"><a href=
4395 "actions-file.html#CRUNCH-OUTGOING-COOKIES">crunch-outgoing-cookies</a></tt>
4396 and allows you to browse websites that insist or rely on
4397 setting cookies, without compromising your privacy too
4400 <p>Most browsers will not permanently store cookies that have
4401 been processed by <tt class="LITERAL">session-cookies-only</tt>
4402 and will forget about them between sessions. This makes
4403 profiling cookies useless, but won't break sites which require
4404 cookies so that you can log in for transactions. This is
4405 generally turned on for all sites, and is the recommended
4408 <p>It makes <span class="emphasis"><i class="EMPHASIS">no sense
4409 at all</i></span> to use <tt class=
4410 "LITERAL">session-cookies-only</tt> together with <tt class=
4412 "actions-file.html#CRUNCH-INCOMING-COOKIES">crunch-incoming-cookies</a></tt>
4413 or <tt class="LITERAL"><a href=
4414 "actions-file.html#CRUNCH-OUTGOING-COOKIES">crunch-outgoing-cookies</a></tt>.
4415 If you do, cookies will be plainly killed.</p>
4417 <p>Note that it is up to the browser how it handles such
4418 cookies without an <span class="QUOTE">"expires"</span> field.
4419 If you use an exotic browser, you might want to try it out to
4422 <p>This setting also has no effect on cookies that may have
4423 been stored previously by the browser before starting
4424 <span class="APPLICATION">Privoxy</span>. These would have to
4425 be removed manually.</p>
4427 <p><span class="APPLICATION">Privoxy</span> also uses the
4429 "actions-file.html#FILTER-CONTENT-COOKIES">content-cookies
4430 filter</a> to block some types of cookies. Content cookies are
4431 not effected by <tt class=
4432 "LITERAL">session-cookies-only</tt>.</p>
4435 <dt>Example usage:</dt>
4438 <table border="0" bgcolor="#E0E0E0" width="90%">
4441 <pre class="SCREEN">
4442 +session-cookies-only
4453 <h4 class="SECT3"><a name="SET-IMAGE-BLOCKER" id=
4454 "SET-IMAGE-BLOCKER">8.5.35. set-image-blocker</a></h4>
4456 <div class="VARIABLELIST">
4458 <dt>Typical use:</dt>
4461 <p>Choose the replacement for blocked images</p>
4467 <p>This action alone doesn't do anything noticeable. If
4468 <span class="emphasis"><i class="EMPHASIS">both</i></span>
4469 <tt class="LITERAL"><a href=
4470 "actions-file.html#BLOCK">block</a></tt> <span class=
4471 "emphasis"><i class="EMPHASIS">and</i></span> <tt class=
4473 "actions-file.html#HANDLE-AS-IMAGE">handle-as-image</a></tt>
4474 <span class="emphasis"><i class="EMPHASIS">also</i></span>
4475 apply, i.e. if the request is to be blocked as an image,
4476 <span class="emphasis"><i class="EMPHASIS">then</i></span> the
4477 parameter of this action decides what will be sent as a
4484 <p>Parameterized.</p>
4492 <p><span class="QUOTE">"pattern"</span> to send a built-in
4493 checkerboard pattern image. The image is visually decent,
4494 scales very well, and makes it obvious where banners were
4499 <p><span class="QUOTE">"blank"</span> to send a built-in
4500 transparent image. This makes banners disappear completely,
4501 but makes it hard to detect where <span class=
4502 "APPLICATION">Privoxy</span> has blocked images on a given
4503 page and complicates troubleshooting if <span class=
4504 "APPLICATION">Privoxy</span> has blocked innocent images,
4505 like navigation icons.</p>
4509 <p><span class="QUOTE">"<tt class=
4510 "REPLACEABLE"><i>target-url</i></tt>"</span> to send a
4511 redirect to <tt class="REPLACEABLE"><i>target-url</i></tt>.
4512 You can redirect to any image anywhere, even in your local
4513 filesystem via <span class="QUOTE">"file:///"</span> URL.
4514 (But note that not all browsers support redirecting to a
4515 local file system).</p>
4517 <p>A good application of redirects is to use special
4518 <span class="APPLICATION">Privoxy</span>-built-in URLs,
4519 which send the built-in images, as <tt class=
4520 "REPLACEABLE"><i>target-url</i></tt>. This has the same
4521 visual effect as specifying <span class=
4522 "QUOTE">"blank"</span> or <span class=
4523 "QUOTE">"pattern"</span> in the first place, but enables
4524 your browser to cache the replacement image, instead of
4525 requesting it over and over again.</p>
4533 <p>The URLs for the built-in images are <span class=
4534 "QUOTE">"http://config.privoxy.org/send-banner?type=<tt class=
4535 "REPLACEABLE"><i>type</i></tt>"</span>, where <tt class=
4536 "REPLACEABLE"><i>type</i></tt> is either <span class=
4537 "QUOTE">"blank"</span> or <span class=
4538 "QUOTE">"pattern"</span>.</p>
4540 <p>There is a third (advanced) type, called <span class=
4541 "QUOTE">"auto"</span>. It is <span class="emphasis"><i class=
4542 "EMPHASIS">NOT</i></span> to be used in <tt class=
4543 "LITERAL">set-image-blocker</tt>, but meant for use from
4544 <a href="filter-file.html">filters</a>. Auto will select the
4545 type of image that would have applied to the referring page,
4546 had it been an image.</p>
4549 <dt>Example usage:</dt>
4552 <p>Built-in pattern:</p>
4554 <table border="0" bgcolor="#E0E0E0" width="90%">
4557 <pre class="SCREEN">
4558 +set-image-blocker{pattern}
4564 <p>Redirect to the BSD daemon:</p>
4566 <table border="0" bgcolor="#E0E0E0" width="90%">
4569 <pre class="SCREEN">
4570 +set-image-blocker{http://www.freebsd.org/gifs/dae_up3.gif}
4576 <p>Redirect to the built-in pattern for better caching:</p>
4578 <table border="0" bgcolor="#E0E0E0" width="90%">
4581 <pre class="SCREEN">
4582 +set-image-blocker{http://config.privoxy.org/send-banner?type=pattern}
4593 <h3 class="SECT3"><a name="SUMMARY" id="SUMMARY">8.5.36.
4596 <p>Note that many of these actions have the potential to cause a page
4597 to misbehave, possibly even not to display at all. There are many
4598 ways a site designer may choose to design his site, and what HTTP
4599 header content, and other criteria, he may depend on. There is no way
4600 to have hard and fast rules for all sites. See the <a href=
4601 "appendix.html#ACTIONSANAT">Appendix</a> for a brief example on
4602 troubleshooting actions.</p>
4607 <h2 class="SECT2"><a name="ALIASES" id="ALIASES">8.6. Aliases</a></h2>
4609 <p>Custom <span class="QUOTE">"actions"</span>, known to <span class=
4610 "APPLICATION">Privoxy</span> as <span class="QUOTE">"aliases"</span>,
4611 can be defined by combining other actions. These can in turn be invoked
4612 just like the built-in actions. Currently, an alias name can contain
4613 any character except space, tab, <span class="QUOTE">"="</span>,
4614 <span class="QUOTE">"{"</span> and <span class="QUOTE">"}"</span>, but
4615 we <span class="emphasis"><i class="EMPHASIS">strongly
4616 recommend</i></span> that you only use <span class="QUOTE">"a"</span>
4617 to <span class="QUOTE">"z"</span>, <span class="QUOTE">"0"</span> to
4618 <span class="QUOTE">"9"</span>, <span class="QUOTE">"+"</span>, and
4619 <span class="QUOTE">"-"</span>. Alias names are not case sensitive, and
4620 are not required to start with a <span class="QUOTE">"+"</span> or
4621 <span class="QUOTE">"-"</span> sign, since they are merely textually
4624 <p>Aliases can be used throughout the actions file, but they
4625 <span class="emphasis"><i class="EMPHASIS">must be defined in a special
4626 section at the top of the file!</i></span> And there can only be one
4627 such section per actions file. Each actions file may have its own alias
4628 section, and the aliases defined in it are only visible within that
4631 <p>There are two main reasons to use aliases: One is to save typing for
4632 frequently used combinations of actions, the other one is a gain in
4633 flexibility: If you decide once how you want to handle shops by
4634 defining an alias called <span class="QUOTE">"shop"</span>, you can
4635 later change your policy on shops in <span class="emphasis"><i class=
4636 "EMPHASIS">one</i></span> place, and your changes will take effect
4637 everywhere in the actions file where the <span class=
4638 "QUOTE">"shop"</span> alias is used. Calling aliases by their purpose
4639 also makes your actions files more readable.</p>
4641 <p>Currently, there is one big drawback to using aliases, though:
4642 <span class="APPLICATION">Privoxy</span>'s built-in web-based action
4643 file editor honors aliases when reading the actions files, but it
4644 expands them before writing. So the effects of your aliases are of
4645 course preserved, but the aliases themselves are lost when you edit
4646 sections that use aliases with it.</p>
4648 <p>Now let's define some aliases...</p>
4650 <table border="0" bgcolor="#E0E0E0" width="100%">
4653 <pre class="SCREEN">
4654 # Useful custom aliases we can use later.
4656 # Note the (required!) section header line and that this section
4657 # must be at the top of the actions file!
4661 # These aliases just save typing later:
4662 # (Note that some already use other aliases!)
4664 +crunch-all-cookies = +<a href=
4665 "actions-file.html#CRUNCH-INCOMING-COOKIES">crunch-incoming-cookies</a> +<a href="actions-file.html#CRUNCH-OUTGOING-COOKIES">crunch-outgoing-cookies</a>
4666 -crunch-all-cookies = -<a href=
4667 "actions-file.html#CRUNCH-INCOMING-COOKIES">crunch-incoming-cookies</a> -<a href="actions-file.html#CRUNCH-OUTGOING-COOKIES">crunch-outgoing-cookies</a>
4668 +block-as-image = +block{Blocked image.} +handle-as-image
4669 allow-all-cookies = -crunch-all-cookies -<a href=
4670 "actions-file.html#SESSION-COOKIES-ONLY">session-cookies-only</a> -<a href=
4671 "actions-file.html#FILTER-CONTENT-COOKIES">filter{content-cookies}</a>
4673 # These aliases define combinations of actions
4674 # that are useful for certain types of sites:
4676 fragile = -<a href="actions-file.html#BLOCK">block</a> -<a href=
4677 "actions-file.html#FILTER">filter</a> -crunch-all-cookies -<a href=
4678 "actions-file.html#FAST-REDIRECTS">fast-redirects</a> -<a href=
4679 "actions-file.html#HIDE-REFERER">hide-referrer</a> -<a href=
4680 "actions-file.html#PREVENT-COMPRESSION">prevent-compression</a>
4682 shop = -crunch-all-cookies -<a href=
4683 "actions-file.html#FILTER-ALL-POPUPS">filter{all-popups}</a>
4685 # Short names for other aliases, for really lazy people ;-)
4687 c0 = +crunch-all-cookies
4688 c1 = -crunch-all-cookies
4694 <p>...and put them to use. These sections would appear in the lower
4695 part of an actions file and define exceptions to the default actions
4696 (as specified further up for the <span class="QUOTE">"/"</span>
4699 <table border="0" bgcolor="#E0E0E0" width="100%">
4702 <pre class="SCREEN">
4703 # These sites are either very complex or very keen on
4704 # user data and require minimal interference to work:
4707 .office.microsoft.com
4708 .windowsupdate.microsoft.com
4709 # Gmail is really mail.google.com, not gmail.com
4713 # Allow cookies (for setting and retrieving your customer data)
4717 .worldpay.com # for quietpc.com
4720 # These shops require pop-ups:
4722 {-filter{all-popups} -filter{unsolicited-popups}}
4730 <p>Aliases like <span class="QUOTE">"shop"</span> and <span class=
4731 "QUOTE">"fragile"</span> are typically used for <span class=
4732 "QUOTE">"problem"</span> sites that require more than one action to be
4733 disabled in order to function properly.</p>
4737 <h2 class="SECT2"><a name="ACT-EXAMPLES" id="ACT-EXAMPLES">8.7. Actions
4738 Files Tutorial</a></h2>
4740 <p>The above chapters have shown <a href="actions-file.html">which
4741 actions files there are and how they are organized</a>, how actions are
4742 <a href="actions-file.html#ACTIONS">specified</a> and <a href=
4743 "actions-file.html#ACTIONS-APPLY">applied to URLs</a>, how <a href=
4744 "actions-file.html#AF-PATTERNS">patterns</a> work, and how to define
4745 and use <a href="actions-file.html#ALIASES">aliases</a>. Now, let's
4746 look at an example <tt class="FILENAME">match-all.action</tt>,
4747 <tt class="FILENAME">default.action</tt> and <tt class=
4748 "FILENAME">user.action</tt> file and see how all these pieces come
4752 <h3 class="SECT3"><a name="MATCH-ALL" id="MATCH-ALL">8.7.1.
4753 match-all.action</a></h3>
4755 <p>Remember <span class="emphasis"><i class="EMPHASIS">all actions
4756 are disabled when matching starts</i></span>, so we have to
4757 explicitly enable the ones we want.</p>
4759 <p>While the <tt class="FILENAME">match-all.action</tt> file only
4760 contains a single section, it is probably the most important one. It
4761 has only one pattern, <span class="QUOTE">"<tt class=
4762 "LITERAL">/</tt>"</span>, but this pattern <a href=
4763 "actions-file.html#AF-PATTERNS">matches all URLs</a>. Therefore, the
4764 set of actions used in this <span class="QUOTE">"default"</span>
4765 section <span class="emphasis"><i class="EMPHASIS">will be applied to
4766 all requests as a start</i></span>. It can be partly or wholly
4767 overridden by other actions files like <tt class=
4768 "FILENAME">default.action</tt> and <tt class=
4769 "FILENAME">user.action</tt>, but it will still be largely responsible
4770 for your overall browsing experience.</p>
4772 <p>Again, at the start of matching, all actions are disabled, so
4773 there is no need to disable any actions here. (Remember: a
4774 <span class="QUOTE">"+"</span> preceding the action name enables the
4775 action, a <span class="QUOTE">"-"</span> disables!). Also note how
4776 this long line has been made more readable by splitting it into
4777 multiple lines with line continuation.</p>
4779 <table border="0" bgcolor="#E0E0E0" width="100%">
4782 <pre class="SCREEN">
4785 "actions-file.html#CHANGE-X-FORWARDED-FOR">change-x-forwarded-for{block}</a> \
4786 +<a href="actions-file.html#HIDE-FROM-HEADER">hide-from-header{block}</a> \
4788 "actions-file.html#SET-IMAGE-BLOCKER">set-image-blocker{pattern}</a> \
4797 <p>The default behavior is now set.</p>
4801 <h3 class="SECT3"><a name="DEFAULT-ACTION" id="DEFAULT-ACTION">8.7.2.
4802 default.action</a></h3>
4804 <p>If you aren't a developer, there's no need for you to edit the
4805 <tt class="FILENAME">default.action</tt> file. It is maintained by
4806 the <span class="APPLICATION">Privoxy</span> developers and if you
4807 disagree with some of the sections, you should overrule them in your
4808 <tt class="FILENAME">user.action</tt>.</p>
4810 <p>Understanding the <tt class="FILENAME">default.action</tt> file
4811 can help you with your <tt class="FILENAME">user.action</tt>,
4814 <p>The first section in this file is a special section for internal
4815 use that prevents older <span class="APPLICATION">Privoxy</span>
4816 versions from reading the file:</p>
4818 <table border="0" bgcolor="#E0E0E0" width="100%">
4821 <pre class="SCREEN">
4822 ##########################################################################
4823 # Settings -- Don't change! For internal Privoxy use ONLY.
4824 ##########################################################################
4826 for-privoxy-version=3.0.11
4832 <p>After that comes the (optional) alias section. We'll use the
4833 example section from the above <a href=
4834 "actions-file.html#ALIASES">chapter on aliases</a>, that also
4835 explains why and how aliases are used:</p>
4837 <table border="0" bgcolor="#E0E0E0" width="100%">
4840 <pre class="SCREEN">
4841 ##########################################################################
4843 ##########################################################################
4846 # These aliases just save typing later:
4847 # (Note that some already use other aliases!)
4849 +crunch-all-cookies = +<a href=
4850 "actions-file.html#CRUNCH-INCOMING-COOKIES">crunch-incoming-cookies</a> +<a href="actions-file.html#CRUNCH-OUTGOING-COOKIES">crunch-outgoing-cookies</a>
4851 -crunch-all-cookies = -<a href=
4852 "actions-file.html#CRUNCH-INCOMING-COOKIES">crunch-incoming-cookies</a> -<a href="actions-file.html#CRUNCH-OUTGOING-COOKIES">crunch-outgoing-cookies</a>
4853 +block-as-image = +block{Blocked image.} +handle-as-image
4854 mercy-for-cookies = -crunch-all-cookies -<a href=
4855 "actions-file.html#SESSION-COOKIES-ONLY">session-cookies-only</a> -<a href=
4856 "actions-file.html#FILTER-CONTENT-COOKIES">filter{content-cookies}</a>
4858 # These aliases define combinations of actions
4859 # that are useful for certain types of sites:
4861 fragile = -<a href="actions-file.html#BLOCK">block</a> -<a href=
4862 "actions-file.html#FILTER">filter</a> -crunch-all-cookies -<a href=
4863 "actions-file.html#FAST-REDIRECTS">fast-redirects</a> -<a href=
4864 "actions-file.html#HIDE-REFERER">hide-referrer</a>
4865 shop = -crunch-all-cookies -<a href=
4866 "actions-file.html#FILTER-ALL-POPUPS">filter{all-popups}</a>
4872 <p>The first of our specialized sections is concerned with
4873 <span class="QUOTE">"fragile"</span> sites, i.e. sites that require
4874 minimum interference, because they are either very complex or very
4875 keen on tracking you (and have mechanisms in place that make them
4876 unusable for people who avoid being tracked). We will simply use our
4877 pre-defined <tt class="LITERAL">fragile</tt> alias instead of stating
4878 the list of actions explicitly:</p>
4880 <table border="0" bgcolor="#E0E0E0" width="100%">
4883 <pre class="SCREEN">
4884 ##########################################################################
4885 # Exceptions for sites that'll break under the default action set:
4886 ##########################################################################
4888 # "Fragile" Use a minimum set of actions for these sites (see alias above):
4891 .office.microsoft.com # surprise, surprise!
4892 .windowsupdate.microsoft.com
4899 <p>Shopping sites are not as fragile, but they typically require
4900 cookies to log in, and pop-up windows for shopping carts or item
4901 details. Again, we'll use a pre-defined alias:</p>
4903 <table border="0" bgcolor="#E0E0E0" width="100%">
4906 <pre class="SCREEN">
4911 .worldpay.com # for quietpc.com
4919 <p>The <tt class="LITERAL"><a href=
4920 "actions-file.html#FAST-REDIRECTS">fast-redirects</a></tt> action,
4921 which may have been enabled in <tt class=
4922 "FILENAME">match-all.action</tt>, breaks some sites. So disable it
4923 for popular sites where we know it misbehaves:</p>
4925 <table border="0" bgcolor="#E0E0E0" width="100%">
4928 <pre class="SCREEN">
4929 { -<a href="actions-file.html#FAST-REDIRECTS">fast-redirects</a> }
4933 .altavista.com/.*(like|url|link):http
4934 .altavista.com/trans.*urltext=http
4941 <p>It is important that <span class="APPLICATION">Privoxy</span>
4942 knows which URLs belong to images, so that <span class=
4943 "emphasis"><i class="EMPHASIS">if</i></span> they are to be blocked,
4944 a substitute image can be sent, rather than an HTML page. Contacting
4945 the remote site to find out is not an option, since it would destroy
4946 the loading time advantage of banner blocking, and it would feed the
4947 advertisers information about you. We can mark any URL as an image
4948 with the <tt class="LITERAL"><a href=
4949 "actions-file.html#HANDLE-AS-IMAGE">handle-as-image</a></tt> action,
4950 and marking all URLs that end in a known image file extension is a
4953 <table border="0" bgcolor="#E0E0E0" width="100%">
4956 <pre class="SCREEN">
4957 ##########################################################################
4959 ##########################################################################
4961 # Define which file types will be treated as images, in case they get
4962 # blocked further down this file:
4964 { +<a href="actions-file.html#HANDLE-AS-IMAGE">handle-as-image</a> }
4965 /.*\.(gif|jpe?g|png|bmp|ico)$
4971 <p>And then there are known banner sources. They often use scripts to
4972 generate the banners, so it won't be visible from the URL that the
4973 request is for an image. Hence we block them <span class=
4974 "emphasis"><i class="EMPHASIS">and</i></span> mark them as images in
4975 one go, with the help of our <tt class="LITERAL">+block-as-image</tt>
4976 alias defined above. (We could of course just as well use <tt class=
4977 "LITERAL">+<a href="actions-file.html#BLOCK">block</a> +<a href=
4978 "actions-file.html#HANDLE-AS-IMAGE">handle-as-image</a></tt> here.)
4979 Remember that the type of the replacement image is chosen by the
4980 <tt class="LITERAL"><a href=
4981 "actions-file.html#SET-IMAGE-BLOCKER">set-image-blocker</a></tt>
4982 action. Since all URLs have matched the default section with its
4983 <tt class="LITERAL">+<a href=
4984 "actions-file.html#SET-IMAGE-BLOCKER">set-image-blocker</a>{pattern}</tt>
4985 action before, it still applies and needn't be repeated:</p>
4987 <table border="0" bgcolor="#E0E0E0" width="100%">
4990 <pre class="SCREEN">
4991 # Known ad generators:
4996 .ad.*.doubleclick.net
4997 .a.yimg.com/(?:(?!/i/).)*$
4998 .a[0-9].yimg.com/(?:(?!/i/).)*$
5006 <p>One of the most important jobs of <span class=
5007 "APPLICATION">Privoxy</span> is to block banners. Many of these can
5008 be <span class="QUOTE">"blocked"</span> by the <tt class=
5010 "actions-file.html#FILTER">filter</a>{banners-by-size}</tt> action,
5011 which we enabled above, and which deletes the references to banner
5012 images from the pages while they are loaded, so the browser doesn't
5013 request them anymore, and hence they don't need to be blocked here.
5014 But this naturally doesn't catch all banners, and some people choose
5015 not to use filters, so we need a comprehensive list of patterns for
5016 banner URLs here, and apply the <tt class="LITERAL"><a href=
5017 "actions-file.html#BLOCK">block</a></tt> action to them.</p>
5019 <p>First comes many generic patterns, which do most of the work, by
5020 matching typical domain and path name components of banners. Then
5021 comes a list of individual patterns for specific sites, which is
5022 omitted here to keep the example short:</p>
5024 <table border="0" bgcolor="#E0E0E0" width="100%">
5027 <pre class="SCREEN">
5028 ##########################################################################
5029 # Block these fine banners:
5030 ##########################################################################
5031 { <a href="actions-file.html#BLOCK">+block{Banner ads.}</a> }
5039 /.*count(er)?\.(pl|cgi|exe|dll|asp|php[34]?)
5040 /(?:.*/)?(publicite|werbung|rekla(ma|me|am)|annonse|maino(kset|nta|s)?)/
5042 # Site-specific patterns (abbreviated):
5050 <p>It's quite remarkable how many advertisers actually call their
5051 banner servers ads.<tt class="REPLACEABLE"><i>company</i></tt>.com,
5052 or call the directory in which the banners are stored simply
5053 <span class="QUOTE">"banners"</span>. So the above generic patterns
5054 are surprisingly effective.</p>
5056 <p>But being very generic, they necessarily also catch URLs that we
5057 don't want to block. The pattern <tt class="LITERAL">.*ads.</tt> e.g.
5058 catches <span class="QUOTE">"nasty-<span class="emphasis"><i class=
5059 "EMPHASIS">ads</i></span>.nasty-corp.com"</span> as intended, but
5060 also <span class="QUOTE">"downlo<span class="emphasis"><i class=
5061 "EMPHASIS">ads</i></span>.sourcefroge.net"</span> or <span class=
5062 "QUOTE">"<span class="emphasis"><i class=
5063 "EMPHASIS">ads</i></span>l.some-provider.net."</span> So here come
5064 some well-known exceptions to the <tt class="LITERAL">+<a href=
5065 "actions-file.html#BLOCK">block</a></tt> section above.</p>
5067 <p>Note that these are exceptions to exceptions from the default!
5068 Consider the URL <span class=
5069 "QUOTE">"downloads.sourcefroge.net"</span>: Initially, all actions
5070 are deactivated, so it wouldn't get blocked. Then comes the defaults
5071 section, which matches the URL, but just deactivates the <tt class=
5072 "LITERAL"><a href="actions-file.html#BLOCK">block</a></tt> action
5073 once again. Then it matches <tt class="LITERAL">.*ads.</tt>, an
5074 exception to the general non-blocking policy, and suddenly <tt class=
5075 "LITERAL"><a href="actions-file.html#BLOCK">+block</a></tt> applies.
5076 And now, it'll match <tt class="LITERAL">.*loads.</tt>, where
5077 <tt class="LITERAL"><a href="actions-file.html#BLOCK">-block</a></tt>
5078 applies, so (unless it matches <span class="emphasis"><i class=
5079 "EMPHASIS">again</i></span> further down) it ends up with no
5080 <tt class="LITERAL"><a href="actions-file.html#BLOCK">block</a></tt>
5081 action applying.</p>
5083 <table border="0" bgcolor="#E0E0E0" width="100%">
5086 <pre class="SCREEN">
5087 ##########################################################################
5088 # Save some innocent victims of the above generic block patterns:
5089 ##########################################################################
5093 { -<a href="actions-file.html#BLOCK">block</a> }
5094 adv[io]*. # (for advogato.org and advice.*)
5095 adsl. # (has nothing to do with ads)
5096 adobe. # (has nothing to do with ads either)
5097 ad[ud]*. # (adult.* and add.*)
5098 .edu # (universities don't host banners (yet!))
5099 .*loads. # (downloads, uploads etc)
5107 www.globalintersec.com/adv # (adv = advanced)
5108 www.ugu.com/sui/ugu/adv
5114 <p>Filtering source code can have nasty side effects, so make an
5115 exception for our friends at sourceforge.net, and all paths with
5116 <span class="QUOTE">"cvs"</span> in them. Note that <tt class=
5117 "LITERAL">-<a href="actions-file.html#FILTER">filter</a></tt>
5118 disables <span class="emphasis"><i class="EMPHASIS">all</i></span>
5119 filters in one fell swoop!</p>
5121 <table border="0" bgcolor="#E0E0E0" width="100%">
5124 <pre class="SCREEN">
5125 # Don't filter code!
5127 { -<a href="actions-file.html#FILTER">filter</a> }
5138 <p>The actual <tt class="FILENAME">default.action</tt> is of course
5139 much more comprehensive, but we hope this example made clear how it
5144 <h3 class="SECT3"><a name="USER-ACTION" id="USER-ACTION">8.7.3.
5145 user.action</a></h3>
5147 <p>So far we are painting with a broad brush by setting general
5148 policies, which would be a reasonable starting point for many people.
5149 Now, you might want to be more specific and have customized rules
5150 that are more suitable to your personal habits and preferences. These
5151 would be for narrowly defined situations like your ISP or your bank,
5152 and should be placed in <tt class="FILENAME">user.action</tt>, which
5153 is parsed after all other actions files and hence has the last word,
5154 over-riding any previously defined actions. <tt class=
5155 "FILENAME">user.action</tt> is also a <span class=
5156 "emphasis"><i class="EMPHASIS">safe</i></span> place for your
5157 personal settings, since <tt class="FILENAME">default.action</tt> is
5158 actively maintained by the <span class="APPLICATION">Privoxy</span>
5159 developers and you'll probably want to install updated versions from
5162 <p>So let's look at a few examples of things that one might typically
5163 do in <tt class="FILENAME">user.action</tt>:</p>
5165 <table border="0" bgcolor="#E0E0E0" width="100%">
5168 <pre class="SCREEN">
5169 # My user.action file. <fred@example.com>
5175 <p>As <a href="actions-file.html#ALIASES">aliases</a> are local to
5176 the actions file that they are defined in, you can't use the ones
5177 from <tt class="FILENAME">default.action</tt>, unless you repeat them
5180 <table border="0" bgcolor="#E0E0E0" width="100%">
5183 <pre class="SCREEN">
5184 # Aliases are local to the file they are defined in.
5185 # (Re-)define aliases for this file:
5189 # These aliases just save typing later, and the alias names should
5190 # be self explanatory.
5192 +crunch-all-cookies = +crunch-incoming-cookies +crunch-outgoing-cookies
5193 -crunch-all-cookies = -crunch-incoming-cookies -crunch-outgoing-cookies
5194 allow-all-cookies = -crunch-all-cookies -session-cookies-only
5195 allow-popups = -filter{all-popups}
5196 +block-as-image = +block{Blocked as image.} +handle-as-image
5197 -block-as-image = -block
5199 # These aliases define combinations of actions that are useful for
5200 # certain types of sites:
5202 fragile = -block -crunch-all-cookies -filter -fast-redirects -hide-referrer
5203 shop = -crunch-all-cookies allow-popups
5205 # Allow ads for selected useful free sites:
5207 allow-ads = -block -filter{banners-by-size} -filter{banners-by-link}
5209 # Alias for specific file types that are text, but might have conflicting
5210 # MIME types. We want the browser to force these to be text documents.
5211 handle-as-text = -<a href="actions-file.html#FILTER">filter</a> +-<a href=
5212 "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>
5218 <p>Say you have accounts on some sites that you visit regularly, and
5219 you don't want to have to log in manually each time. So you'd like to
5220 allow persistent cookies for these sites. The <tt class=
5221 "LITERAL">allow-all-cookies</tt> alias defined above does exactly
5222 that, i.e. it disables crunching of cookies in any direction, and the
5223 processing of cookies to make them only temporary.</p>
5225 <table border="0" bgcolor="#E0E0E0" width="100%">
5228 <pre class="SCREEN">
5229 { allow-all-cookies }
5239 <p>Your bank is allergic to some filter, but you don't know which, so
5240 you disable them all:</p>
5242 <table border="0" bgcolor="#E0E0E0" width="100%">
5245 <pre class="SCREEN">
5246 { -<a href="actions-file.html#FILTER">filter</a> }
5247 .your-home-banking-site.com
5253 <p>Some file types you may not want to filter for various
5256 <table border="0" bgcolor="#E0E0E0" width="100%">
5259 <pre class="SCREEN">
5260 # Technical documentation is likely to contain strings that might
5261 # erroneously get altered by the JavaScript-oriented filters:
5266 # And this stupid host sends streaming video with a wrong MIME type,
5267 # so that Privoxy thinks it is getting HTML and starts filtering:
5269 stupid-server.example.com/
5275 <p>Example of a simple <a href="actions-file.html#BLOCK">block</a>
5276 action. Say you've seen an ad on your favourite page on example.com
5277 that you want to get rid of. You have right-clicked the image,
5278 selected <span class="QUOTE">"copy image location"</span> and pasted
5279 the URL below while removing the leading http://, into a <tt class=
5280 "LITERAL">{ +block{} }</tt> section. Note that <tt class="LITERAL">{
5281 +handle-as-image }</tt> need not be specified, since all URLs ending
5282 in <tt class="LITERAL">.gif</tt> will be tagged as images by the
5283 general rules as set in default.action anyway:</p>
5285 <table border="0" bgcolor="#E0E0E0" width="100%">
5288 <pre class="SCREEN">
5289 { +<a href="actions-file.html#BLOCK">block</a>{Nasty ads.} }
5290 www.example.com/nasty-ads/sponsor\.gif
5291 another.example.net/more/junk/here/
5297 <p>The URLs of dynamically generated banners, especially from large
5298 banner farms, often don't use the well-known image file name
5299 extensions, which makes it impossible for <span class=
5300 "APPLICATION">Privoxy</span> to guess the file type just by looking
5301 at the URL. You can use the <tt class="LITERAL">+block-as-image</tt>
5302 alias defined above for these cases. Note that objects which match
5303 this rule but then turn out NOT to be an image are typically rendered
5304 as a <span class="QUOTE">"broken image"</span> icon by the browser.
5307 <table border="0" bgcolor="#E0E0E0" width="100%">
5310 <pre class="SCREEN">
5321 <p>Now you noticed that the default configuration breaks Forbes
5322 Magazine, but you were too lazy to find out which action is the
5323 culprit, and you were again too lazy to give <a href=
5324 "contact.html">feedback</a>, so you just used the <tt class=
5325 "LITERAL">fragile</tt> alias on the site, and -- <span class=
5326 "emphasis"><i class="EMPHASIS">whoa!</i></span> -- it worked. The
5327 <tt class="LITERAL">fragile</tt> aliases disables those actions that
5328 are most likely to break a site. Also, good for testing purposes to
5329 see if it is <span class="APPLICATION">Privoxy</span> that is causing
5330 the problem or not. We later find other regular sites that misbehave,
5331 and add those to our personalized list of troublemakers:</p>
5333 <table border="0" bgcolor="#E0E0E0" width="100%">
5336 <pre class="SCREEN">
5346 <p>You like the <span class="QUOTE">"fun"</span> text replacements in
5347 <tt class="FILENAME">default.filter</tt>, but it is disabled in the
5348 distributed actions file. So you'd like to turn it on in your
5349 private, update-safe config, once and for all:</p>
5351 <table border="0" bgcolor="#E0E0E0" width="100%">
5354 <pre class="SCREEN">
5355 { +<a href="actions-file.html#FILTER-FUN">filter{fun}</a> }
5362 <p>Note that the above is not really a good idea: There are
5363 exceptions to the filters in <tt class="FILENAME">default.action</tt>
5364 for things that really shouldn't be filtered, like code on
5365 CVS->Web interfaces. Since <tt class="FILENAME">user.action</tt>
5366 has the last word, these exceptions won't be valid for the
5367 <span class="QUOTE">"fun"</span> filtering specified here.</p>
5369 <p>You might also worry about how your favourite free websites are
5370 funded, and find that they rely on displaying banner advertisements
5371 to survive. So you might want to specifically allow banners for those
5372 sites that you feel provide value to you:</p>
5374 <table border="0" bgcolor="#E0E0E0" width="100%">
5377 <pre class="SCREEN">
5387 <p>Note that <tt class="LITERAL">allow-ads</tt> has been aliased to
5388 <tt class="LITERAL">-<a href=
5389 "actions-file.html#BLOCK">block</a></tt>, <tt class=
5391 "actions-file.html#FILTER-BANNERS-BY-SIZE">filter{banners-by-size}</a></tt>,
5392 and <tt class="LITERAL">-<a href=
5393 "actions-file.html#FILTER-BANNERS-BY-LINK">filter{banners-by-link}</a></tt>
5396 <p>Invoke another alias here to force an over-ride of the MIME type
5397 <tt class="LITERAL">application/x-sh</tt> which typically would open
5398 a download type dialog. In my case, I want to look at the shell
5399 script, and then I can save it should I choose to.</p>
5401 <table border="0" bgcolor="#E0E0E0" width="100%">
5404 <pre class="SCREEN">
5412 <p><tt class="FILENAME">user.action</tt> is generally the best place
5413 to define exceptions and additions to the default policies of
5414 <tt class="FILENAME">default.action</tt>. Some actions are safe to
5415 have their default policies set here though. So let's set a default
5416 policy to have a <span class="QUOTE">"blank"</span> image as opposed
5417 to the checkerboard pattern for <span class="emphasis"><i class=
5418 "EMPHASIS">ALL</i></span> sites. <span class="QUOTE">"/"</span> of
5419 course matches all URL paths and patterns:</p>
5421 <table border="0" bgcolor="#E0E0E0" width="100%">
5424 <pre class="SCREEN">
5426 "actions-file.html#SET-IMAGE-BLOCKER">set-image-blocker{blank}</a> }
5436 <div class="NAVFOOTER">
5437 <hr align="left" width="100%">
5439 <table summary="Footer navigation table" width="100%" border="0"
5440 cellpadding="0" cellspacing="0">
5442 <td width="33%" align="left" valign="top"><a href="config.html"
5443 accesskey="P">Prev</a></td>
5445 <td width="34%" align="center" valign="top"><a href="index.html"
5446 accesskey="H">Home</a></td>
5448 <td width="33%" align="right" valign="top"><a href="filter-file.html"
5449 accesskey="N">Next</a></td>
5453 <td width="33%" align="left" valign="top">The Main Configuration
5456 <td width="34%" align="center" valign="top"> </td>
5458 <td width="33%" align="right" valign="top">Filter Files</td>