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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="AEN2676" id="AEN2676"></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/show-client-tags" target=
859 "_top">http://config.privoxy.org/show-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-header{X-User-Tracking: sucks}
1078 <h4 class="SECT3"><a name="BLOCK" id="BLOCK">8.5.2. block</a></h4>
1080 <div class="VARIABLELIST">
1082 <dt>Typical use:</dt>
1085 <p>Block ads or other unwanted content</p>
1091 <p>Requests for URLs to which this action applies are blocked,
1092 i.e. the requests are trapped by <span class=
1093 "APPLICATION">Privoxy</span> and the requested URL is never
1094 retrieved, but is answered locally with a substitute page or
1095 image, as determined by the <tt class="LITERAL"><a href=
1096 "actions-file.html#HANDLE-AS-IMAGE">handle-as-image</a></tt>,
1097 <tt class="LITERAL"><a href=
1098 "actions-file.html#SET-IMAGE-BLOCKER">set-image-blocker</a></tt>,
1099 and <tt class="LITERAL"><a href=
1100 "actions-file.html#HANDLE-AS-EMPTY-DOCUMENT">handle-as-empty-document</a></tt>
1107 <p>Parameterized.</p>
1113 <p>A block reason that should be given to the user.</p>
1119 <p><span class="APPLICATION">Privoxy</span> sends a special
1120 <span class="QUOTE">"BLOCKED"</span> page for requests to
1121 blocked pages. This page contains the block reason given as
1122 parameter, a link to find out why the block action applies, and
1123 a click-through to the blocked content (the latter only if the
1124 force feature is available and enabled).</p>
1126 <p>A very important exception occurs if <span class=
1127 "emphasis"><i class="EMPHASIS">both</i></span> <tt class=
1128 "LITERAL">block</tt> and <tt class="LITERAL"><a href=
1129 "actions-file.html#HANDLE-AS-IMAGE">handle-as-image</a></tt>,
1130 apply to the same request: it will then be replaced by an
1131 image. If <tt class="LITERAL"><a href=
1132 "actions-file.html#SET-IMAGE-BLOCKER">set-image-blocker</a></tt>
1133 (see below) also applies, the type of image will be determined
1134 by its parameter, if not, the standard checkerboard pattern is
1137 <p>It is important to understand this process, in order to
1138 understand how <span class="APPLICATION">Privoxy</span> deals
1139 with ads and other unwanted content. Blocking is a core
1140 feature, and one upon which various other features depend.</p>
1142 <p>The <tt class="LITERAL"><a href=
1143 "actions-file.html#FILTER">filter</a></tt> action can perform a
1144 very similar task, by <span class="QUOTE">"blocking"</span>
1145 banner images and other content through rewriting the relevant
1146 URLs in the document's HTML source, so they don't get requested
1147 in the first place. Note that this is a totally different
1148 technique, and it's easy to confuse the two.</p>
1151 <dt>Example usage (section):</dt>
1154 <table border="0" bgcolor="#E0E0E0" width="90%">
1157 <pre class="SCREEN">
1158 {+block{No nasty stuff for you.}}
1159 # Block and replace with "blocked" page
1160 .nasty-stuff.example.com
1162 {+block{Doubleclick banners.} +handle-as-image}
1163 # Block and replace with image
1167 {+block{Layered ads.} +handle-as-empty-document}
1168 # Block and then ignore
1169 adserver.example.net/.*\.js$
1180 <h4 class="SECT3"><a name="CHANGE-X-FORWARDED-FOR" id=
1181 "CHANGE-X-FORWARDED-FOR">8.5.3. change-x-forwarded-for</a></h4>
1183 <div class="VARIABLELIST">
1185 <dt>Typical use:</dt>
1188 <p>Improve privacy by not forwarding the source of the request
1189 in the HTTP headers.</p>
1195 <p>Deletes the <span class="QUOTE">"X-Forwarded-For:"</span>
1196 HTTP header from the client request, or adds a new one.</p>
1202 <p>Parameterized.</p>
1210 <p><span class="QUOTE">"block"</span> to delete the
1215 <p><span class="QUOTE">"add"</span> to create the header
1216 (or append the client's IP address to an already existing
1225 <p>It is safe and recommended to use <tt class=
1226 "LITERAL">block</tt>.</p>
1228 <p>Forwarding the source address of the request may make sense
1229 in some multi-user setups but is also a privacy risk.</p>
1232 <dt>Example usage:</dt>
1235 <table border="0" bgcolor="#E0E0E0" width="90%">
1238 <pre class="SCREEN">
1239 +change-x-forwarded-for{block}
1250 <h4 class="SECT3"><a name="CLIENT-HEADER-FILTER" id=
1251 "CLIENT-HEADER-FILTER">8.5.4. client-header-filter</a></h4>
1253 <div class="VARIABLELIST">
1255 <dt>Typical use:</dt>
1258 <p>Rewrite or remove single client headers.</p>
1264 <p>All client headers to which this action applies are filtered
1265 on-the-fly through the specified regular expression based
1278 <p>The name of a client-header filter, as defined in one of the
1279 <a href="filter-file.html">filter files</a>.</p>
1285 <p>Client-header filters are applied to each header on its own,
1286 not to all at once. This makes it easier to diagnose problems,
1287 but on the downside you can't write filters that only change
1288 header x if header y's value is z. You can do that by using
1291 <p>Client-header filters are executed after the other header
1292 actions have finished and use their output as input.</p>
1294 <p>If the request URI gets changed, <span class=
1295 "APPLICATION">Privoxy</span> will detect that and use the new
1296 one. This can be used to rewrite the request destination behind
1297 the client's back, for example to specify a Tor exit relay for
1298 certain requests.</p>
1300 <p>Please refer to the <a href="filter-file.html">filter file
1301 chapter</a> to learn which client-header filters are available
1302 by default, and how to create your own.</p>
1305 <dt>Example usage (section):</dt>
1308 <table border="0" bgcolor="#E0E0E0" width="90%">
1311 <pre class="SCREEN">
1312 # Hide Tor exit notation in Host and Referer Headers
1313 {+client-header-filter{hide-tor-exit-notation}}
1326 <h4 class="SECT3"><a name="CLIENT-HEADER-TAGGER" id=
1327 "CLIENT-HEADER-TAGGER">8.5.5. client-header-tagger</a></h4>
1329 <div class="VARIABLELIST">
1331 <dt>Typical use:</dt>
1334 <p>Block requests based on their headers.</p>
1340 <p>Client headers to which this action applies are filtered
1341 on-the-fly through the specified regular expression based
1342 substitutions, the result is used as tag.</p>
1354 <p>The name of a client-header tagger, as defined in one of the
1355 <a href="filter-file.html">filter files</a>.</p>
1361 <p>Client-header taggers are applied to each header on its own,
1362 and as the header isn't modified, each tagger <span class=
1363 "QUOTE">"sees"</span> the original.</p>
1365 <p>Client-header taggers are the first actions that are
1366 executed and their tags can be used to control every other
1370 <dt>Example usage (section):</dt>
1373 <table border="0" bgcolor="#E0E0E0" width="90%">
1376 <pre class="SCREEN">
1377 # Tag every request with the User-Agent header
1378 {+client-header-tagger{user-agent}}
1381 # Tagging itself doesn't change the action
1382 # settings, sections with TAG patterns do:
1384 # If it's a download agent, use a different forwarding proxy,
1385 # show the real User-Agent and make sure resume works.
1386 {+forward-override{forward-socks5 10.0.0.2:2222 .} \
1387 -hide-if-modified-since \
1388 -overwrite-last-modified \
1393 TAG:^User-Agent: NetBSD-ftp/
1394 TAG:^User-Agent: Novell ZYPP Installer
1395 TAG:^User-Agent: RPM APT-HTTP/
1396 TAG:^User-Agent: fetch libfetch/
1397 TAG:^User-Agent: Ubuntu APT-HTTP/
1398 TAG:^User-Agent: MPlayer/
1405 <table border="0" bgcolor="#E0E0E0" width="90%">
1408 <pre class="SCREEN">
1409 # Tag all requests with the Range header set
1410 {+client-header-tagger{range-requests}}
1413 # Disable filtering for the tagged requests.
1415 # With filtering enabled Privoxy would remove the Range headers
1416 # to be able to filter the whole response. The downside is that
1417 # it prevents clients from resuming downloads or skipping over
1418 # parts of multimedia files.
1419 {-filter -deanimate-gifs}
1432 <h4 class="SECT3"><a name="CONTENT-TYPE-OVERWRITE" id=
1433 "CONTENT-TYPE-OVERWRITE">8.5.6. content-type-overwrite</a></h4>
1435 <div class="VARIABLELIST">
1437 <dt>Typical use:</dt>
1440 <p>Stop useless download menus from popping up, or change the
1441 browser's rendering mode</p>
1447 <p>Replaces the <span class="QUOTE">"Content-Type:"</span> HTTP
1454 <p>Parameterized.</p>
1466 <p>The <span class="QUOTE">"Content-Type:"</span> HTTP server
1467 header is used by the browser to decide what to do with the
1468 document. The value of this header can cause the browser to
1469 open a download menu instead of displaying the document by
1470 itself, even if the document's format is supported by the
1473 <p>The declared content type can also affect which rendering
1474 mode the browser chooses. If XHTML is delivered as <span class=
1475 "QUOTE">"text/html"</span>, many browsers treat it as yet
1476 another broken HTML document. If it is send as <span class=
1477 "QUOTE">"application/xml"</span>, browsers with XHTML support
1478 will only display it, if the syntax is correct.</p>
1480 <p>If you see a web site that proudly uses XHTML buttons, but
1481 sets <span class="QUOTE">"Content-Type: text/html"</span>, you
1482 can use <span class="APPLICATION">Privoxy</span> to overwrite
1483 it with <span class="QUOTE">"application/xml"</span> and
1484 validate the web master's claim inside your XHTML-supporting
1485 browser. If the syntax is incorrect, the browser will complain
1488 <p>You can also go the opposite direction: if your browser
1489 prints error messages instead of rendering a document falsely
1490 declared as XHTML, you can overwrite the content type with
1491 <span class="QUOTE">"text/html"</span> and have it rendered as
1492 broken HTML document.</p>
1494 <p>By default <tt class="LITERAL">content-type-overwrite</tt>
1495 only replaces <span class="QUOTE">"Content-Type:"</span>
1496 headers that look like some kind of text. If you want to
1497 overwrite it unconditionally, you have to combine it with
1498 <tt class="LITERAL"><a href=
1499 "actions-file.html#FORCE-TEXT-MODE">force-text-mode</a></tt>.
1500 This limitation exists for a reason, think twice before
1501 circumventing it.</p>
1503 <p>Most of the time it's easier to replace this action with a
1504 custom <tt class="LITERAL"><a href=
1505 "actions-file.html#SERVER-HEADER-FILTER">server-header
1506 filter</a></tt>. It allows you to activate it for every
1507 document of a certain site and it will still only replace the
1508 content types you aimed at.</p>
1510 <p>Of course you can apply <tt class=
1511 "LITERAL">content-type-overwrite</tt> to a whole site and then
1512 make URL based exceptions, but it's a lot more work to get the
1516 <dt>Example usage (sections):</dt>
1519 <table border="0" bgcolor="#E0E0E0" width="90%">
1522 <pre class="SCREEN">
1523 # Check if www.example.net/ really uses valid XHTML
1524 { +content-type-overwrite{application/xml} }
1527 # but leave the content type unmodified if the URL looks like a style sheet
1528 {-content-type-overwrite}
1529 www.example.net/.*\.css$
1530 www.example.net/.*style
1541 <h4 class="SECT3"><a name="CRUNCH-CLIENT-HEADER" id=
1542 "CRUNCH-CLIENT-HEADER">8.5.7. crunch-client-header</a></h4>
1544 <div class="VARIABLELIST">
1546 <dt>Typical use:</dt>
1549 <p>Remove a client header <span class=
1550 "APPLICATION">Privoxy</span> has no dedicated action for.</p>
1556 <p>Deletes every header sent by the client that contains the
1557 string the user supplied as parameter.</p>
1563 <p>Parameterized.</p>
1575 <p>This action allows you to block client headers for which no
1576 dedicated <span class="APPLICATION">Privoxy</span> action
1577 exists. <span class="APPLICATION">Privoxy</span> will remove
1578 every client header that contains the string you supplied as
1581 <p>Regular expressions are <span class="emphasis"><i class=
1582 "EMPHASIS">not supported</i></span> and you can't use this
1583 action to block different headers in the same request, unless
1584 they contain the same string.</p>
1586 <p><tt class="LITERAL">crunch-client-header</tt> is only meant
1587 for quick tests. If you have to block several different
1588 headers, or only want to modify parts of them, you should use a
1589 <tt class="LITERAL"><a href=
1590 "actions-file.html#CLIENT-HEADER-FILTER">client-header
1591 filter</a></tt>.</p>
1593 <div class="WARNING">
1594 <table class="WARNING" border="1" width="90%">
1596 <td align="center"><b>Warning</b></td>
1601 <p>Don't block any header without understanding the
1609 <dt>Example usage (section):</dt>
1612 <table border="0" bgcolor="#E0E0E0" width="90%">
1615 <pre class="SCREEN">
1616 # Block the non-existent "Privacy-Violation:" client header
1617 { +crunch-client-header{Privacy-Violation:} }
1630 <h4 class="SECT3"><a name="CRUNCH-IF-NONE-MATCH" id=
1631 "CRUNCH-IF-NONE-MATCH">8.5.8. crunch-if-none-match</a></h4>
1633 <div class="VARIABLELIST">
1635 <dt>Typical use:</dt>
1638 <p>Prevent yet another way to track the user's steps between
1645 <p>Deletes the <span class="QUOTE">"If-None-Match:"</span> HTTP
1664 <p>Removing the <span class="QUOTE">"If-None-Match:"</span>
1665 HTTP client header is useful for filter testing, where you want
1666 to force a real reload instead of getting status code
1667 <span class="QUOTE">"304"</span> which would cause the browser
1668 to use a cached copy of the page.</p>
1670 <p>It is also useful to make sure the header isn't used as a
1671 cookie replacement (unlikely but possible).</p>
1673 <p>Blocking the <span class="QUOTE">"If-None-Match:"</span>
1674 header shouldn't cause any caching problems, as long as the
1675 <span class="QUOTE">"If-Modified-Since:"</span> header isn't
1676 blocked or missing as well.</p>
1678 <p>It is recommended to use this action together with
1679 <tt class="LITERAL"><a href=
1680 "actions-file.html#HIDE-IF-MODIFIED-SINCE">hide-if-modified-since</a></tt>
1681 and <tt class="LITERAL"><a href=
1682 "actions-file.html#OVERWRITE-LAST-MODIFIED">overwrite-last-modified</a></tt>.</p>
1685 <dt>Example usage (section):</dt>
1688 <table border="0" bgcolor="#E0E0E0" width="90%">
1691 <pre class="SCREEN">
1692 # Let the browser revalidate cached documents but don't
1693 # allow the server to use the revalidation headers for user tracking.
1694 {+hide-if-modified-since{-60} \
1695 +overwrite-last-modified{randomize} \
1696 +crunch-if-none-match}
1708 <h4 class="SECT3"><a name="CRUNCH-INCOMING-COOKIES" id=
1709 "CRUNCH-INCOMING-COOKIES">8.5.9. crunch-incoming-cookies</a></h4>
1711 <div class="VARIABLELIST">
1713 <dt>Typical use:</dt>
1716 <p>Prevent the web server from setting HTTP cookies on your
1723 <p>Deletes any <span class="QUOTE">"Set-Cookie:"</span> HTTP
1724 headers from server replies.</p>
1742 <p>This action is only concerned with <span class=
1743 "emphasis"><i class="EMPHASIS">incoming</i></span> HTTP
1744 cookies. For <span class="emphasis"><i class=
1745 "EMPHASIS">outgoing</i></span> HTTP cookies, use <tt class=
1747 "actions-file.html#CRUNCH-OUTGOING-COOKIES">crunch-outgoing-cookies</a></tt>.
1748 Use <span class="emphasis"><i class="EMPHASIS">both</i></span>
1749 to disable HTTP cookies completely.</p>
1751 <p>It makes <span class="emphasis"><i class="EMPHASIS">no sense
1752 at all</i></span> to use this action in conjunction with the
1753 <tt class="LITERAL"><a href=
1754 "actions-file.html#SESSION-COOKIES-ONLY">session-cookies-only</a></tt>
1755 action, since it would prevent the session cookies from being
1756 set. See also <tt class="LITERAL"><a href=
1757 "actions-file.html#FILTER-CONTENT-COOKIES">filter-content-cookies</a></tt>.</p>
1760 <dt>Example usage:</dt>
1763 <table border="0" bgcolor="#E0E0E0" width="90%">
1766 <pre class="SCREEN">
1767 +crunch-incoming-cookies
1778 <h4 class="SECT3"><a name="CRUNCH-SERVER-HEADER" id=
1779 "CRUNCH-SERVER-HEADER">8.5.10. crunch-server-header</a></h4>
1781 <div class="VARIABLELIST">
1783 <dt>Typical use:</dt>
1786 <p>Remove a server header <span class=
1787 "APPLICATION">Privoxy</span> has no dedicated action for.</p>
1793 <p>Deletes every header sent by the server that contains the
1794 string the user supplied as parameter.</p>
1800 <p>Parameterized.</p>
1812 <p>This action allows you to block server headers for which no
1813 dedicated <span class="APPLICATION">Privoxy</span> action
1814 exists. <span class="APPLICATION">Privoxy</span> will remove
1815 every server header that contains the string you supplied as
1818 <p>Regular expressions are <span class="emphasis"><i class=
1819 "EMPHASIS">not supported</i></span> and you can't use this
1820 action to block different headers in the same request, unless
1821 they contain the same string.</p>
1823 <p><tt class="LITERAL">crunch-server-header</tt> is only meant
1824 for quick tests. If you have to block several different
1825 headers, or only want to modify parts of them, you should use a
1826 custom <tt class="LITERAL"><a href=
1827 "actions-file.html#SERVER-HEADER-FILTER">server-header
1828 filter</a></tt>.</p>
1830 <div class="WARNING">
1831 <table class="WARNING" border="1" width="90%">
1833 <td align="center"><b>Warning</b></td>
1838 <p>Don't block any header without understanding the
1846 <dt>Example usage (section):</dt>
1849 <table border="0" bgcolor="#E0E0E0" width="90%">
1852 <pre class="SCREEN">
1853 # Crunch server headers that try to prevent caching
1854 { +crunch-server-header{no-cache} }
1866 <h4 class="SECT3"><a name="CRUNCH-OUTGOING-COOKIES" id=
1867 "CRUNCH-OUTGOING-COOKIES">8.5.11. crunch-outgoing-cookies</a></h4>
1869 <div class="VARIABLELIST">
1871 <dt>Typical use:</dt>
1874 <p>Prevent the web server from reading any HTTP cookies from
1881 <p>Deletes any <span class="QUOTE">"Cookie:"</span> HTTP
1882 headers from client requests.</p>
1900 <p>This action is only concerned with <span class=
1901 "emphasis"><i class="EMPHASIS">outgoing</i></span> HTTP
1902 cookies. For <span class="emphasis"><i class=
1903 "EMPHASIS">incoming</i></span> HTTP cookies, use <tt class=
1905 "actions-file.html#CRUNCH-INCOMING-COOKIES">crunch-incoming-cookies</a></tt>.
1906 Use <span class="emphasis"><i class="EMPHASIS">both</i></span>
1907 to disable HTTP cookies completely.</p>
1909 <p>It makes <span class="emphasis"><i class="EMPHASIS">no sense
1910 at all</i></span> to use this action in conjunction with the
1911 <tt class="LITERAL"><a href=
1912 "actions-file.html#SESSION-COOKIES-ONLY">session-cookies-only</a></tt>
1913 action, since it would prevent the session cookies from being
1917 <dt>Example usage:</dt>
1920 <table border="0" bgcolor="#E0E0E0" width="90%">
1923 <pre class="SCREEN">
1924 +crunch-outgoing-cookies
1935 <h4 class="SECT3"><a name="DEANIMATE-GIFS" id=
1936 "DEANIMATE-GIFS">8.5.12. deanimate-gifs</a></h4>
1938 <div class="VARIABLELIST">
1940 <dt>Typical use:</dt>
1943 <p>Stop those annoying, distracting animated GIF images.</p>
1949 <p>De-animate GIF animations, i.e. reduce them to their first
1956 <p>Parameterized.</p>
1962 <p><span class="QUOTE">"last"</span> or <span class=
1963 "QUOTE">"first"</span></p>
1969 <p>This will also shrink the images considerably (in bytes, not
1970 pixels!). If the option <span class="QUOTE">"first"</span> is
1971 given, the first frame of the animation is used as the
1972 replacement. If <span class="QUOTE">"last"</span> is given, the
1973 last frame of the animation is used instead, which probably
1974 makes more sense for most banner animations, but also has the
1975 risk of not showing the entire last frame (if it is only a
1976 delta to an earlier frame).</p>
1978 <p>You can safely use this action with patterns that will also
1979 match non-GIF objects, because no attempt will be made at
1980 anything that doesn't look like a GIF.</p>
1983 <dt>Example usage:</dt>
1986 <table border="0" bgcolor="#E0E0E0" width="90%">
1989 <pre class="SCREEN">
1990 +deanimate-gifs{last}
2001 <h4 class="SECT3"><a name="DOWNGRADE-HTTP-VERSION" id=
2002 "DOWNGRADE-HTTP-VERSION">8.5.13. downgrade-http-version</a></h4>
2004 <div class="VARIABLELIST">
2006 <dt>Typical use:</dt>
2009 <p>Work around (very rare) problems with HTTP/1.1</p>
2015 <p>Downgrades HTTP/1.1 client requests and server replies to
2034 <p>This is a left-over from the time when <span class=
2035 "APPLICATION">Privoxy</span> didn't support important HTTP/1.1
2036 features well. It is left here for the unlikely case that you
2037 experience HTTP/1.1-related problems with some server out
2040 <p>Note that enabling this action is only a workaround. It
2041 should not be enabled for sites that work without it. While it
2042 shouldn't break any pages, it has an (usually negative)
2043 performance impact.</p>
2045 <p>If you come across a site where enabling this action helps,
2046 please report it, so the cause of the problem can be analyzed.
2047 If the problem turns out to be caused by a bug in <span class=
2048 "APPLICATION">Privoxy</span> it should be fixed so the
2049 following release works without the work around.</p>
2052 <dt>Example usage (section):</dt>
2055 <table border="0" bgcolor="#E0E0E0" width="90%">
2058 <pre class="SCREEN">
2059 {+downgrade-http-version}
2060 problem-host.example.com
2071 <h4 class="SECT3"><a name="EXTERNAL-FILTER" id=
2072 "EXTERNAL-FILTER">8.5.14. external-filter</a></h4>
2074 <div class="VARIABLELIST">
2076 <dt>Typical use:</dt>
2079 <p>Modify content using a programming language of your
2086 <p>All instances of text-based type, most notably HTML and
2087 JavaScript, to which this action applies, can be filtered
2088 on-the-fly through the specified external filter. By default
2089 plain text documents are exempted from filtering, because web
2090 servers often use the <tt class="LITERAL">text/plain</tt> MIME
2091 type for all files whose type they don't know.)</p>
2103 <p>The name of an external content filter, as defined in the
2104 <a href="filter-file.html">filter file</a>. External filters
2105 can be defined in one or more files as defined by the
2106 <tt class="LITERAL"><a href=
2107 "config.html#FILTERFILE">filterfile</a></tt> option in the
2108 <a href="config.html">config file</a>.</p>
2110 <p>When used in its negative form, and without parameters,
2111 <span class="emphasis"><i class="EMPHASIS">all</i></span>
2112 filtering with external filters is completely disabled.</p>
2118 <p>External filters are scripts or programs that can modify the
2119 content in case common <tt class="LITERAL"><a href=
2120 "actions-file.html#FILTER">filters</a></tt> aren't powerful
2121 enough. With the exception that this action doesn't use
2122 pcrs-based filters, the notes in the <tt class=
2123 "LITERAL"><a href="actions-file.html#FILTER">filter</a></tt>
2126 <div class="WARNING">
2127 <table class="WARNING" border="1" width="90%">
2129 <td align="center"><b>Warning</b></td>
2134 <p>Currently external filters are executed with
2135 <span class="APPLICATION">Privoxy</span>'s privileges.
2136 Only use external filters you understand and trust.</p>
2142 <p>This feature is experimental, the <tt class=
2144 "filter-file.html#EXTERNAL-FILTER-SYNTAX">syntax</a></tt> may
2145 change in the future.</p>
2148 <dt>Example usage:</dt>
2151 <table border="0" bgcolor="#E0E0E0" width="90%">
2154 <pre class="SCREEN">
2155 +external-filter{fancy-filter}
2166 <h4 class="SECT3"><a name="FAST-REDIRECTS" id=
2167 "FAST-REDIRECTS">8.5.15. fast-redirects</a></h4>
2169 <div class="VARIABLELIST">
2171 <dt>Typical use:</dt>
2174 <p>Fool some click-tracking scripts and speed up indirect
2181 <p>Detects redirection URLs and redirects the browser without
2182 contacting the redirection server first.</p>
2188 <p>Parameterized.</p>
2196 <p><span class="QUOTE">"simple-check"</span> to just search
2197 for the string <span class="QUOTE">"http://"</span> to
2198 detect redirection URLs.</p>
2202 <p><span class="QUOTE">"check-decoded-url"</span> to decode
2203 URLs (if necessary) before searching for redirection
2212 <p>Many sites, like yahoo.com, don't just link to other sites.
2213 Instead, they will link to some script on their own servers,
2214 giving the destination as a parameter, which will then redirect
2215 you to the final target. URLs resulting from this scheme
2216 typically look like: <span class=
2217 "QUOTE">"http://www.example.org/click-tracker.cgi?target=http%3a//www.example.net/"</span>.</p>
2219 <p>Sometimes, there are even multiple consecutive redirects
2220 encoded in the URL. These redirections via scripts make your
2221 web browsing more traceable, since the server from which you
2222 follow such a link can see where you go to. Apart from that,
2223 valuable bandwidth and time is wasted, while your browser asks
2224 the server for one redirect after the other. Plus, it feeds the
2227 <p>This feature is currently not very smart and is scheduled
2228 for improvement. If it is enabled by default, you will have to
2229 create some exceptions to this action. It can lead to failures
2230 in several ways:</p>
2232 <p>Not every URLs with other URLs as parameters is evil. Some
2233 sites offer a real service that requires this information to
2234 work. For example a validation service needs to know, which
2235 document to validate. <tt class="LITERAL">fast-redirects</tt>
2236 assumes that every URL parameter that looks like another URL is
2237 a redirection target, and will always redirect to the last one.
2238 Most of the time the assumption is correct, but if it isn't,
2239 the user gets redirected anyway.</p>
2241 <p>Another failure occurs if the URL contains other parameters
2242 after the URL parameter. The URL: <span class=
2243 "QUOTE">"http://www.example.org/?redirect=http%3a//www.example.net/&foo=bar"</span>.
2244 contains the redirection URL <span class=
2245 "QUOTE">"http://www.example.net/"</span>, followed by another
2246 parameter. <tt class="LITERAL">fast-redirects</tt> doesn't know
2247 that and will cause a redirect to <span class=
2248 "QUOTE">"http://www.example.net/&foo=bar"</span>. Depending
2249 on the target server configuration, the parameter will be
2250 silently ignored or lead to a <span class="QUOTE">"page not
2251 found"</span> error. You can prevent this problem by first
2252 using the <tt class="LITERAL"><a href=
2253 "actions-file.html#REDIRECT">redirect</a></tt> action to remove
2254 the last part of the URL, but it requires a little effort.</p>
2256 <p>To detect a redirection URL, <tt class=
2257 "LITERAL">fast-redirects</tt> only looks for the string
2258 <span class="QUOTE">"http://"</span>, either in plain text
2259 (invalid but often used) or encoded as <span class=
2260 "QUOTE">"http%3a//"</span>. Some sites use their own URL
2261 encoding scheme, encrypt the address of the target server or
2262 replace it with a database id. In theses cases <tt class=
2263 "LITERAL">fast-redirects</tt> is fooled and the request reaches
2264 the redirection server where it probably gets logged.</p>
2267 <dt>Example usage:</dt>
2270 <table border="0" bgcolor="#E0E0E0" width="90%">
2273 <pre class="SCREEN">
2274 { +fast-redirects{simple-check} }
2277 { +fast-redirects{check-decoded-url} }
2278 another.example.com/testing
2289 <h4 class="SECT3"><a name="FILTER" id="FILTER">8.5.16.
2292 <div class="VARIABLELIST">
2294 <dt>Typical use:</dt>
2297 <p>Get rid of HTML and JavaScript annoyances, banner
2298 advertisements (by size), do fun text replacements, add
2299 personalized effects, etc.</p>
2305 <p>All instances of text-based type, most notably HTML and
2306 JavaScript, to which this action applies, can be filtered
2307 on-the-fly through the specified regular expression based
2308 substitutions. (Note: as of version 3.0.3 plain text documents
2309 are exempted from filtering, because web servers often use the
2310 <tt class="LITERAL">text/plain</tt> MIME type for all files
2311 whose type they don't know.)</p>
2323 <p>The name of a content filter, as defined in the <a href=
2324 "filter-file.html">filter file</a>. Filters can be defined in
2325 one or more files as defined by the <tt class=
2326 "LITERAL"><a href="config.html#FILTERFILE">filterfile</a></tt>
2327 option in the <a href="config.html">config file</a>. <tt class=
2328 "FILENAME">default.filter</tt> is the collection of filters
2329 supplied by the developers. Locally defined filters should go
2330 in their own file, such as <tt class=
2331 "FILENAME">user.filter</tt>.</p>
2333 <p>When used in its negative form, and without parameters,
2334 <span class="emphasis"><i class="EMPHASIS">all</i></span>
2335 filtering is completely disabled.</p>
2341 <p>For your convenience, there are a number of pre-defined
2342 filters available in the distribution filter file that you can
2343 use. See the examples below for a list.</p>
2345 <p>Filtering requires buffering the page content, which may
2346 appear to slow down page rendering since nothing is displayed
2347 until all content has passed the filters. (The total time until
2348 the page is completely rendered doesn't change much, but it may
2349 be perceived as slower since the page is not incrementally
2350 displayed.) This effect will be more noticeable on slower
2353 <p><span class="QUOTE">"Rolling your own"</span> filters
2354 requires a knowledge of <a href=
2355 "http://en.wikipedia.org/wiki/Regular_expressions" target=
2356 "_top"><span class="QUOTE">"Regular Expressions"</span></a> and
2357 <a href="http://en.wikipedia.org/wiki/Html" target=
2358 "_top"><span class="QUOTE">"HTML"</span></a>. This is very
2359 powerful feature, and potentially very intrusive. Filters
2360 should be used with caution, and where an equivalent
2361 <span class="QUOTE">"action"</span> is not available.</p>
2363 <p>The amount of data that can be filtered is limited to the
2364 <tt class="LITERAL"><a href=
2365 "config.html#BUFFER-LIMIT">buffer-limit</a></tt> option in the
2366 main <a href="config.html">config file</a>. The default is 4096
2367 KB (4 Megs). Once this limit is exceeded, the buffered data,
2368 and all pending data, is passed through unfiltered.</p>
2370 <p>Inappropriate MIME types, such as zipped files, are not
2371 filtered at all. (Again, only text-based types except plain
2372 text). Encrypted SSL data (from HTTPS servers) cannot be
2373 filtered either, since this would violate the integrity of the
2374 secure transaction. In some situations it might be necessary to
2375 protect certain text, like source code, from filtering by
2376 defining appropriate <tt class="LITERAL">-filter</tt>
2379 <p>Compressed content can't be filtered either, but if
2380 <span class="APPLICATION">Privoxy</span> is compiled with zlib
2381 support and a supported compression algorithm is used (gzip or
2382 deflate), <span class="APPLICATION">Privoxy</span> can first
2383 decompress the content and then filter it.</p>
2385 <p>If you use a <span class="APPLICATION">Privoxy</span>
2386 version without zlib support, but want filtering to work on as
2387 much documents as possible, even those that would normally be
2388 sent compressed, you must use the <tt class="LITERAL"><a href=
2389 "actions-file.html#PREVENT-COMPRESSION">prevent-compression</a></tt>
2390 action in conjunction with <tt class="LITERAL">filter</tt>.</p>
2392 <p>Content filtering can achieve some of the same effects as
2393 the <tt class="LITERAL"><a href=
2394 "actions-file.html#BLOCK">block</a></tt> action, i.e. it can be
2395 used to block ads and banners. But the mechanism works quite
2396 differently. One effective use, is to block ad banners based on
2397 their size (see below), since many of these seem to be somewhat
2400 <p><a href="contact.html">Feedback</a> with suggestions for new
2401 or improved filters is particularly welcome!</p>
2403 <p>The below list has only the names and a one-line description
2404 of each predefined filter. There are <a href=
2405 "filter-file.html#PREDEFINED-FILTERS">more verbose
2406 explanations</a> of what these filters do in the <a href=
2407 "filter-file.html">filter file chapter</a>.</p>
2410 <dt>Example usage (with filters from the distribution <tt class=
2411 "FILENAME">default.filter</tt> file). See <a href=
2412 "filter-file.html#PREDEFINED-FILTERS">the Predefined Filters
2413 section</a> for more explanation on each:</dt>
2416 <p><a name="FILTER-JS-ANNOYANCES" id=
2417 "FILTER-JS-ANNOYANCES"></a></p>
2419 <table border="0" bgcolor="#E0E0E0" width="90%">
2422 <pre class="SCREEN">
2423 +filter{js-annoyances} # Get rid of particularly annoying JavaScript abuse.
2429 <p><a name="FILTER-JS-EVENTS" id="FILTER-JS-EVENTS"></a></p>
2431 <table border="0" bgcolor="#E0E0E0" width="90%">
2434 <pre class="SCREEN">
2435 +filter{js-events} # Kill JavaScript event bindings and timers (Radically destructive! Only for extra nasty sites).
2441 <p><a name="FILTER-HTML-ANNOYANCES" id=
2442 "FILTER-HTML-ANNOYANCES"></a></p>
2444 <table border="0" bgcolor="#E0E0E0" width="90%">
2447 <pre class="SCREEN">
2448 +filter{html-annoyances} # Get rid of particularly annoying HTML abuse.
2454 <p><a name="FILTER-CONTENT-COOKIES" id=
2455 "FILTER-CONTENT-COOKIES"></a></p>
2457 <table border="0" bgcolor="#E0E0E0" width="90%">
2460 <pre class="SCREEN">
2461 +filter{content-cookies} # Kill cookies that come in the HTML or JS content.
2467 <p><a name="FILTER-REFRESH-TAGS" id=
2468 "FILTER-REFRESH-TAGS"></a></p>
2470 <table border="0" bgcolor="#E0E0E0" width="90%">
2473 <pre class="SCREEN">
2474 +filter{refresh-tags} # Kill automatic refresh tags if refresh time is larger than 9 seconds.
2480 <p><a name="FILTER-UNSOLICITED-POPUPS" id=
2481 "FILTER-UNSOLICITED-POPUPS"></a></p>
2483 <table border="0" bgcolor="#E0E0E0" width="90%">
2486 <pre class="SCREEN">
2487 +filter{unsolicited-popups} # Disable only unsolicited pop-up windows.
2493 <p><a name="FILTER-ALL-POPUPS" id="FILTER-ALL-POPUPS"></a></p>
2495 <table border="0" bgcolor="#E0E0E0" width="90%">
2498 <pre class="SCREEN">
2499 +filter{all-popups} # Kill all popups in JavaScript and HTML.
2505 <p><a name="FILTER-IMG-REORDER" id=
2506 "FILTER-IMG-REORDER"></a></p>
2508 <table border="0" bgcolor="#E0E0E0" width="90%">
2511 <pre class="SCREEN">
2512 +filter{img-reorder} # Reorder attributes in <img> tags to make the banners-by-* filters more effective.
2518 <p><a name="FILTER-BANNERS-BY-SIZE" id=
2519 "FILTER-BANNERS-BY-SIZE"></a></p>
2521 <table border="0" bgcolor="#E0E0E0" width="90%">
2524 <pre class="SCREEN">
2525 +filter{banners-by-size} # Kill banners by size.
2531 <p><a name="FILTER-BANNERS-BY-LINK" id=
2532 "FILTER-BANNERS-BY-LINK"></a></p>
2534 <table border="0" bgcolor="#E0E0E0" width="90%">
2537 <pre class="SCREEN">
2538 +filter{banners-by-link} # Kill banners by their links to known clicktrackers.
2544 <p><a name="FILTER-WEBBUGS" id="FILTER-WEBBUGS"></a></p>
2546 <table border="0" bgcolor="#E0E0E0" width="90%">
2549 <pre class="SCREEN">
2550 +filter{webbugs} # Squish WebBugs (1x1 invisible GIFs used for user tracking).
2556 <p><a name="FILTER-TINY-TEXTFORMS" id=
2557 "FILTER-TINY-TEXTFORMS"></a></p>
2559 <table border="0" bgcolor="#E0E0E0" width="90%">
2562 <pre class="SCREEN">
2563 +filter{tiny-textforms} # Extend those tiny textareas up to 40x80 and kill the hard wrap.
2569 <p><a name="FILTER-JUMPING-WINDOWS" id=
2570 "FILTER-JUMPING-WINDOWS"></a></p>
2572 <table border="0" bgcolor="#E0E0E0" width="90%">
2575 <pre class="SCREEN">
2576 +filter{jumping-windows} # Prevent windows from resizing and moving themselves.
2582 <p><a name="FILTER-FRAMESET-BORDERS" id=
2583 "FILTER-FRAMESET-BORDERS"></a></p>
2585 <table border="0" bgcolor="#E0E0E0" width="90%">
2588 <pre class="SCREEN">
2589 +filter{frameset-borders} # Give frames a border and make them resizable.
2595 <p><a name="FILTER-IFRAMES" id="FILTER-IFRAMES"></a></p>
2597 <table border="0" bgcolor="#E0E0E0" width="90%">
2600 <pre class="SCREEN">
2601 +filter{iframes} # Removes all detected iframes. Should only be enabled for individual sites.
2607 <p><a name="FILTER-DEMORONIZER" id=
2608 "FILTER-DEMORONIZER"></a></p>
2610 <table border="0" bgcolor="#E0E0E0" width="90%">
2613 <pre class="SCREEN">
2614 +filter{demoronizer} # Fix MS's non-standard use of standard charsets.
2620 <p><a name="FILTER-SHOCKWAVE-FLASH" id=
2621 "FILTER-SHOCKWAVE-FLASH"></a></p>
2623 <table border="0" bgcolor="#E0E0E0" width="90%">
2626 <pre class="SCREEN">
2627 +filter{shockwave-flash} # Kill embedded Shockwave Flash objects.
2633 <p><a name="FILTER-QUICKTIME-KIOSKMODE" id=
2634 "FILTER-QUICKTIME-KIOSKMODE"></a></p>
2636 <table border="0" bgcolor="#E0E0E0" width="90%">
2639 <pre class="SCREEN">
2640 +filter{quicktime-kioskmode} # Make Quicktime movies saveable.
2646 <p><a name="FILTER-FUN" id="FILTER-FUN"></a></p>
2648 <table border="0" bgcolor="#E0E0E0" width="90%">
2651 <pre class="SCREEN">
2652 +filter{fun} # Text replacements for subversive browsing fun!
2658 <p><a name="FILTER-CRUDE-PARENTAL" id=
2659 "FILTER-CRUDE-PARENTAL"></a></p>
2661 <table border="0" bgcolor="#E0E0E0" width="90%">
2664 <pre class="SCREEN">
2665 +filter{crude-parental} # Crude parental filtering. Note that this filter doesn't work reliably.
2671 <p><a name="FILTER-IE-EXPLOITS" id=
2672 "FILTER-IE-EXPLOITS"></a></p>
2674 <table border="0" bgcolor="#E0E0E0" width="90%">
2677 <pre class="SCREEN">
2678 +filter{ie-exploits} # Disable some known Internet Explorer bug exploits.
2684 <p><a name="FILTER-SITE-SPECIFICS" id=
2685 "FILTER-SITE-SPECIFICS"></a></p>
2687 <table border="0" bgcolor="#E0E0E0" width="90%">
2690 <pre class="SCREEN">
2691 +filter{site-specifics} # Cure for site-specific problems. Don't apply generally!
2697 <p><a name="FILTER-NO-PING" id="FILTER-NO-PING"></a></p>
2699 <table border="0" bgcolor="#E0E0E0" width="90%">
2702 <pre class="SCREEN">
2703 +filter{no-ping} # Removes non-standard ping attributes in <a> and <area> tags.
2709 <p><a name="FILTER-GOOGLE" id="FILTER-GOOGLE"></a></p>
2711 <table border="0" bgcolor="#E0E0E0" width="90%">
2714 <pre class="SCREEN">
2715 +filter{google} # CSS-based block for Google text ads. Also removes a width limitation and the toolbar advertisement.
2721 <p><a name="FILTER-YAHOO" id="FILTER-YAHOO"></a></p>
2723 <table border="0" bgcolor="#E0E0E0" width="90%">
2726 <pre class="SCREEN">
2727 +filter{yahoo} # CSS-based block for Yahoo text ads. Also removes a width limitation.
2733 <p><a name="FILTER-MSN" id="FILTER-MSN"></a></p>
2735 <table border="0" bgcolor="#E0E0E0" width="90%">
2738 <pre class="SCREEN">
2739 +filter{msn} # CSS-based block for MSN text ads. Also removes tracking URLs and a width limitation.
2745 <p><a name="FILTER-BLOGSPOT" id="FILTER-BLOGSPOT"></a></p>
2747 <table border="0" bgcolor="#E0E0E0" width="90%">
2750 <pre class="SCREEN">
2751 +filter{blogspot} # Cleans up some Blogspot blogs. Read the fine print before using this.
2762 <h4 class="SECT3"><a name="FORCE-TEXT-MODE" id=
2763 "FORCE-TEXT-MODE">8.5.17. force-text-mode</a></h4>
2765 <div class="VARIABLELIST">
2767 <dt>Typical use:</dt>
2770 <p>Force <span class="APPLICATION">Privoxy</span> to treat a
2771 document as if it was in some kind of <span class=
2772 "emphasis"><i class="EMPHASIS">text</i></span> format.</p>
2778 <p>Declares a document as text, even if the <span class=
2779 "QUOTE">"Content-Type:"</span> isn't detected as such.</p>
2797 <p>As explained <tt class="LITERAL"><a href=
2798 "actions-file.html#FILTER">above</a></tt>, <span class=
2799 "APPLICATION">Privoxy</span> tries to only filter files that
2800 are in some kind of text format. The same restrictions apply to
2801 <tt class="LITERAL"><a href=
2802 "actions-file.html#CONTENT-TYPE-OVERWRITE">content-type-overwrite</a></tt>.
2803 <tt class="LITERAL">force-text-mode</tt> declares a document as
2804 text, without looking at the <span class=
2805 "QUOTE">"Content-Type:"</span> first.</p>
2807 <div class="WARNING">
2808 <table class="WARNING" border="1" width="90%">
2810 <td align="center"><b>Warning</b></td>
2815 <p>Think twice before activating this action. Filtering
2816 binary data with regular expressions can cause file
2824 <dt>Example usage:</dt>
2827 <table border="0" bgcolor="#E0E0E0" width="90%">
2830 <pre class="SCREEN">
2843 <h4 class="SECT3"><a name="FORWARD-OVERRIDE" id=
2844 "FORWARD-OVERRIDE">8.5.18. forward-override</a></h4>
2846 <div class="VARIABLELIST">
2848 <dt>Typical use:</dt>
2851 <p>Change the forwarding settings based on User-Agent or
2858 <p>Overrules the forward directives in the configuration
2865 <p>Parameterized.</p>
2873 <p><span class="QUOTE">"forward ."</span> to use a direct
2874 connection without any additional proxies.</p>
2878 <p><span class="QUOTE">"forward 127.0.0.1:8123"</span> to
2879 use the HTTP proxy listening at 127.0.0.1 port 8123.</p>
2883 <p><span class="QUOTE">"forward-socks4a 127.0.0.1:9050
2884 ."</span> to use the socks4a proxy listening at 127.0.0.1
2885 port 9050. Replace <span class=
2886 "QUOTE">"forward-socks4a"</span> with <span class=
2887 "QUOTE">"forward-socks4"</span> to use a socks4 connection
2888 (with local DNS resolution) instead, use <span class=
2889 "QUOTE">"forward-socks5"</span> for socks5 connections
2890 (with remote DNS resolution).</p>
2894 <p><span class="QUOTE">"forward-socks4a 127.0.0.1:9050
2895 proxy.example.org:8000"</span> to use the socks4a proxy
2896 listening at 127.0.0.1 port 9050 to reach the HTTP proxy
2897 listening at proxy.example.org port 8000. Replace
2898 <span class="QUOTE">"forward-socks4a"</span> with
2899 <span class="QUOTE">"forward-socks4"</span> to use a socks4
2900 connection (with local DNS resolution) instead, use
2901 <span class="QUOTE">"forward-socks5"</span> for socks5
2902 connections (with remote DNS resolution).</p>
2906 <p><span class="QUOTE">"forward-webserver
2907 127.0.0.1:80"</span> to use the HTTP server listening at
2908 127.0.0.1 port 80 without adjusting the request
2911 <p>This makes it more convenient to use Privoxy to make
2912 existing websites available as onion services as well.</p>
2914 <p>Many websites serve content with hardcoded URLs and
2915 can't be easily adjusted to change the domain based on the
2916 one used by the client.</p>
2918 <p>Putting Privoxy between Tor and the webserver (or an
2919 stunnel that forwards to the webserver) allows to rewrite
2920 headers and content to make client and server happy at the
2923 <p>Using Privoxy for webservers that are only reachable
2924 through onion addresses and whose location is supposed to
2925 be secret is not recommended and should not be necessary
2934 <p>This action takes parameters similar to the <a href=
2935 "config.html#FORWARDING">forward</a> directives in the
2936 configuration file, but without the URL pattern. It can be used
2937 as replacement, but normally it's only used in cases where
2938 matching based on the request URL isn't sufficient.</p>
2940 <div class="WARNING">
2941 <table class="WARNING" border="1" width="90%">
2943 <td align="center"><b>Warning</b></td>
2948 <p>Please read the description for the <a href=
2949 "config.html#FORWARDING">forward</a> directives before
2950 using this action. Forwarding to the wrong people will
2951 reduce your privacy and increase the chances of
2952 man-in-the-middle attacks.</p>
2954 <p>If the ports are missing or invalid, default values
2955 will be used. This might change in the future and you
2956 shouldn't rely on it. Otherwise incorrect syntax causes
2957 Privoxy to exit. Due to design limitations, invalid
2958 parameter syntax isn't detected until the action is
2959 used the first time.</p>
2962 "http://config.privoxy.org/show-url-info" target=
2963 "_top">show-url-info CGI page</a> to verify that your
2964 forward settings do what you thought the do.</p>
2971 <dt>Example usage:</dt>
2974 <table border="0" bgcolor="#E0E0E0" width="90%">
2977 <pre class="SCREEN">
2978 # Use an ssh tunnel for requests previously tagged as
2979 # <span class="QUOTE">"User-Agent: fetch libfetch/2.0"</span> and make sure
2980 # resuming downloads continues to work.
2982 # This way you can continue to use Tor for your normal browsing,
2983 # without overloading the Tor network with your FreeBSD ports updates
2984 # or downloads of bigger files like ISOs.
2986 # Note that HTTP headers are easy to fake and therefore their
2987 # values are as (un)trustworthy as your clients and users.
2988 {+forward-override{forward-socks5 10.0.0.2:2222 .} \
2989 -hide-if-modified-since \
2990 -overwrite-last-modified \
2992 TAG:^User-Agent: fetch libfetch/2\.0$
3004 <h4 class="SECT3"><a name="HANDLE-AS-EMPTY-DOCUMENT" id=
3005 "HANDLE-AS-EMPTY-DOCUMENT">8.5.19. handle-as-empty-document</a></h4>
3007 <div class="VARIABLELIST">
3009 <dt>Typical use:</dt>
3012 <p>Mark URLs that should be replaced by empty documents
3013 <span class="emphasis"><i class="EMPHASIS">if they get
3014 blocked</i></span></p>
3020 <p>This action alone doesn't do anything noticeable. It just
3021 marks URLs. If the <tt class="LITERAL"><a href=
3022 "actions-file.html#BLOCK">block</a></tt> action <span class=
3023 "emphasis"><i class="EMPHASIS">also applies</i></span>, the
3024 presence or absence of this mark decides whether an HTML
3025 <span class="QUOTE">"BLOCKED"</span> page, or an empty document
3026 will be sent to the client as a substitute for the blocked
3027 content. The <span class="emphasis"><i class=
3028 "EMPHASIS">empty</i></span> document isn't literally empty, but
3029 actually contains a single space.</p>
3047 <p>Some browsers complain about syntax errors if JavaScript
3048 documents are blocked with <span class=
3049 "APPLICATION">Privoxy's</span> default HTML page; this option
3050 can be used to silence them. And of course this action can also
3051 be used to eliminate the <span class=
3052 "APPLICATION">Privoxy</span> BLOCKED message in frames.</p>
3054 <p>The content type for the empty document can be specified
3055 with <tt class="LITERAL"><a href=
3056 "actions-file.html#CONTENT-TYPE-OVERWRITE">content-type-overwrite{}</a></tt>,
3057 but usually this isn't necessary.</p>
3060 <dt>Example usage:</dt>
3063 <table border="0" bgcolor="#E0E0E0" width="90%">
3066 <pre class="SCREEN">
3067 # Block all documents on example.org that end with ".js",
3068 # but send an empty document instead of the usual HTML message.
3069 {+block{Blocked JavaScript} +handle-as-empty-document}
3082 <h4 class="SECT3"><a name="HANDLE-AS-IMAGE" id=
3083 "HANDLE-AS-IMAGE">8.5.20. handle-as-image</a></h4>
3085 <div class="VARIABLELIST">
3087 <dt>Typical use:</dt>
3090 <p>Mark URLs as belonging to images (so they'll be replaced by
3091 images <span class="emphasis"><i class="EMPHASIS">if they do
3092 get blocked</i></span>, rather than HTML pages)</p>
3098 <p>This action alone doesn't do anything noticeable. It just
3099 marks URLs as images. If the <tt class="LITERAL"><a href=
3100 "actions-file.html#BLOCK">block</a></tt> action <span class=
3101 "emphasis"><i class="EMPHASIS">also applies</i></span>, the
3102 presence or absence of this mark decides whether an HTML
3103 <span class="QUOTE">"blocked"</span> page, or a replacement
3104 image (as determined by the <tt class="LITERAL"><a href=
3105 "actions-file.html#SET-IMAGE-BLOCKER">set-image-blocker</a></tt>
3106 action) will be sent to the client as a substitute for the
3107 blocked content.</p>
3125 <p>The below generic example section is actually part of
3126 <tt class="FILENAME">default.action</tt>. It marks all URLs
3127 with well-known image file name extensions as images and should
3130 <p>Users will probably only want to use the handle-as-image
3131 action in conjunction with <tt class="LITERAL"><a href=
3132 "actions-file.html#BLOCK">block</a></tt>, to block sources of
3133 banners, whose URLs don't reflect the file type, like in the
3134 second example section.</p>
3136 <p>Note that you cannot treat HTML pages as images in most
3137 cases. For instance, (in-line) ad frames require an HTML page
3138 to be sent, or they won't display properly. Forcing <tt class=
3139 "LITERAL">handle-as-image</tt> in this situation will not
3140 replace the ad frame with an image, but lead to error
3144 <dt>Example usage (sections):</dt>
3147 <table border="0" bgcolor="#E0E0E0" width="90%">
3150 <pre class="SCREEN">
3151 # Generic image extensions:
3154 /.*\.(gif|jpg|jpeg|png|bmp|ico)$
3156 # These don't look like images, but they're banners and should be
3157 # blocked as images:
3159 {+block{Nasty banners.} +handle-as-image}
3160 nasty-banner-server.example.com/junk.cgi\?output=trash
3171 <h4 class="SECT3"><a name="HIDE-ACCEPT-LANGUAGE" id=
3172 "HIDE-ACCEPT-LANGUAGE">8.5.21. hide-accept-language</a></h4>
3174 <div class="VARIABLELIST">
3176 <dt>Typical use:</dt>
3179 <p>Pretend to use different language settings.</p>
3185 <p>Deletes or replaces the <span class=
3186 "QUOTE">"Accept-Language:"</span> HTTP header in client
3193 <p>Parameterized.</p>
3199 <p>Keyword: <span class="QUOTE">"block"</span>, or any user
3206 <p>Faking the browser's language settings can be useful to make
3207 a foreign User-Agent set with <tt class="LITERAL"><a href=
3208 "actions-file.html#HIDE-USER-AGENT">hide-user-agent</a></tt>
3209 more believable.</p>
3211 <p>However some sites with content in different languages check
3212 the <span class="QUOTE">"Accept-Language:"</span> to decide
3213 which one to take by default. Sometimes it isn't possible to
3214 later switch to another language without changing the
3215 <span class="QUOTE">"Accept-Language:"</span> header first.</p>
3217 <p>Therefore it's a good idea to either only change the
3218 <span class="QUOTE">"Accept-Language:"</span> header to
3219 languages you understand, or to languages that aren't wide
3222 <p>Before setting the <span class=
3223 "QUOTE">"Accept-Language:"</span> header to a rare language,
3224 you should consider that it helps to make your requests unique
3225 and thus easier to trace. If you don't plan to change this
3226 header frequently, you should stick to a common language.</p>
3229 <dt>Example usage (section):</dt>
3232 <table border="0" bgcolor="#E0E0E0" width="90%">
3235 <pre class="SCREEN">
3236 # Pretend to use Canadian language settings.
3237 {+hide-accept-language{en-ca} \
3238 +hide-user-agent{Mozilla/5.0 (X11; U; OpenBSD i386; en-CA; rv:1.8.0.4) Gecko/20060628 Firefox/1.5.0.4} \
3251 <h4 class="SECT3"><a name="HIDE-CONTENT-DISPOSITION" id=
3252 "HIDE-CONTENT-DISPOSITION">8.5.22. hide-content-disposition</a></h4>
3254 <div class="VARIABLELIST">
3256 <dt>Typical use:</dt>
3259 <p>Prevent download menus for content you prefer to view inside
3266 <p>Deletes or replaces the <span class=
3267 "QUOTE">"Content-Disposition:"</span> HTTP header set by some
3274 <p>Parameterized.</p>
3280 <p>Keyword: <span class="QUOTE">"block"</span>, or any user
3287 <p>Some servers set the <span class=
3288 "QUOTE">"Content-Disposition:"</span> HTTP header for documents
3289 they assume you want to save locally before viewing them. The
3290 <span class="QUOTE">"Content-Disposition:"</span> header
3291 contains the file name the browser is supposed to use by
3294 <p>In most browsers that understand this header, it makes it
3295 impossible to <span class="emphasis"><i class="EMPHASIS">just
3296 view</i></span> the document, without downloading it first,
3297 even if it's just a simple text file or an image.</p>
3299 <p>Removing the <span class=
3300 "QUOTE">"Content-Disposition:"</span> header helps to prevent
3301 this annoyance, but some browsers additionally check the
3302 <span class="QUOTE">"Content-Type:"</span> header, before they
3303 decide if they can display a document without saving it first.
3304 In these cases, you have to change this header as well, before
3305 the browser stops displaying download menus.</p>
3307 <p>It is also possible to change the server's file name
3308 suggestion to another one, but in most cases it isn't worth the
3309 time to set it up.</p>
3311 <p>This action will probably be removed in the future, use
3312 server-header filters instead.</p>
3315 <dt>Example usage:</dt>
3318 <table border="0" bgcolor="#E0E0E0" width="90%">
3321 <pre class="SCREEN">
3322 # Disarm the download link in Sourceforge's patch tracker
3324 +content-type-overwrite{text/plain}\
3325 +hide-content-disposition{block} }
3326 .sourceforge.net/tracker/download\.php
3337 <h4 class="SECT3"><a name="HIDE-IF-MODIFIED-SINCE" id=
3338 "HIDE-IF-MODIFIED-SINCE">8.5.23. hide-if-modified-since</a></h4>
3340 <div class="VARIABLELIST">
3342 <dt>Typical use:</dt>
3345 <p>Prevent yet another way to track the user's steps between
3352 <p>Deletes the <span class="QUOTE">"If-Modified-Since:"</span>
3353 HTTP client header or modifies its value.</p>
3359 <p>Parameterized.</p>
3365 <p>Keyword: <span class="QUOTE">"block"</span>, or a user
3366 defined value that specifies a range of hours.</p>
3372 <p>Removing this header is useful for filter testing, where you
3373 want to force a real reload instead of getting status code
3374 <span class="QUOTE">"304"</span>, which would cause the browser
3375 to use a cached copy of the page.</p>
3377 <p>Instead of removing the header, <tt class=
3378 "LITERAL">hide-if-modified-since</tt> can also add or subtract
3379 a random amount of time to/from the header's value. You specify
3380 a range of minutes where the random factor should be chosen
3381 from and <span class="APPLICATION">Privoxy</span> does the
3382 rest. A negative value means subtracting, a positive value
3385 <p>Randomizing the value of the <span class=
3386 "QUOTE">"If-Modified-Since:"</span> makes it less likely that
3387 the server can use the time as a cookie replacement, but you
3388 will run into caching problems if the random range is too
3391 <p>It is a good idea to only use a small negative value and let
3392 <tt class="LITERAL"><a href=
3393 "actions-file.html#OVERWRITE-LAST-MODIFIED">overwrite-last-modified</a></tt>
3394 handle the greater changes.</p>
3396 <p>It is also recommended to use this action together with
3397 <tt class="LITERAL"><a href=
3398 "actions-file.html#CRUNCH-IF-NONE-MATCH">crunch-if-none-match</a></tt>,
3399 otherwise it's more or less pointless.</p>
3402 <dt>Example usage (section):</dt>
3405 <table border="0" bgcolor="#E0E0E0" width="90%">
3408 <pre class="SCREEN">
3409 # Let the browser revalidate but make tracking based on the time less likely.
3410 {+hide-if-modified-since{-60} \
3411 +overwrite-last-modified{randomize} \
3412 +crunch-if-none-match}
3424 <h4 class="SECT3"><a name="HIDE-FROM-HEADER" id=
3425 "HIDE-FROM-HEADER">8.5.24. hide-from-header</a></h4>
3427 <div class="VARIABLELIST">
3429 <dt>Typical use:</dt>
3432 <p>Keep your (old and ill) browser from telling web servers
3433 your email address</p>
3439 <p>Deletes any existing <span class="QUOTE">"From:"</span> HTTP
3440 header, or replaces it with the specified string.</p>
3446 <p>Parameterized.</p>
3452 <p>Keyword: <span class="QUOTE">"block"</span>, or any user
3459 <p>The keyword <span class="QUOTE">"block"</span> will
3460 completely remove the header (not to be confused with the
3461 <tt class="LITERAL"><a href=
3462 "actions-file.html#BLOCK">block</a></tt> action).</p>
3464 <p>Alternately, you can specify any value you prefer to be sent
3465 to the web server. If you do, it is a matter of fairness not to
3466 use any address that is actually used by a real person.</p>
3468 <p>This action is rarely needed, as modern web browsers don't
3469 send <span class="QUOTE">"From:"</span> headers anymore.</p>
3472 <dt>Example usage:</dt>
3475 <table border="0" bgcolor="#E0E0E0" width="90%">
3478 <pre class="SCREEN">
3479 +hide-from-header{block}
3485 <table border="0" bgcolor="#E0E0E0" width="90%">
3488 <pre class="SCREEN">
3489 +hide-from-header{spam-me-senseless@sittingduck.example.com}
3500 <h4 class="SECT3"><a name="HIDE-REFERRER" id="HIDE-REFERRER">8.5.25.
3501 hide-referrer</a></h4><a name="HIDE-REFERER" id="HIDE-REFERER"></a>
3503 <div class="VARIABLELIST">
3505 <dt>Typical use:</dt>
3508 <p>Conceal which link you followed to get to a particular
3515 <p>Deletes the <span class="QUOTE">"Referer:"</span> (sic) HTTP
3516 header from the client request, or replaces it with a forged
3523 <p>Parameterized.</p>
3531 <p><span class="QUOTE">"conditional-block"</span> to delete
3532 the header completely if the host has changed.</p>
3536 <p><span class="QUOTE">"conditional-forge"</span> to forge
3537 the header if the host has changed.</p>
3541 <p><span class="QUOTE">"block"</span> to delete the header
3542 unconditionally.</p>
3546 <p><span class="QUOTE">"forge"</span> to pretend to be
3547 coming from the homepage of the server we are talking
3552 <p>Any other string to set a user defined referrer.</p>
3560 <p><tt class="LITERAL">conditional-block</tt> is the only
3561 parameter, that isn't easily detected in the server's log file.
3562 If it blocks the referrer, the request will look like the
3563 visitor used a bookmark or typed in the address directly.</p>
3565 <p>Leaving the referrer unmodified for requests on the same
3566 host allows the server owner to see the visitor's <span class=
3567 "QUOTE">"click path"</span>, but in most cases she could also
3568 get that information by comparing other parts of the log file:
3569 for example the User-Agent if it isn't a very common one, or
3570 the user's IP address if it doesn't change between different
3573 <p>Always blocking the referrer, or using a custom one, can
3574 lead to failures on servers that check the referrer before they
3575 answer any requests, in an attempt to prevent their content
3576 from being embedded or linked to elsewhere.</p>
3578 <p>Both <tt class="LITERAL">conditional-block</tt> and
3579 <tt class="LITERAL">forge</tt> will work with referrer checks,
3580 as long as content and valid referring page are on the same
3581 host. Most of the time that's the case.</p>
3583 <p><tt class="LITERAL">hide-referer</tt> is an alternate
3584 spelling of <tt class="LITERAL">hide-referrer</tt> and the two
3585 can be can be freely substituted with each other. (<span class=
3586 "QUOTE">"referrer"</span> is the correct English spelling,
3587 however the HTTP specification has a bug - it requires it to be
3588 spelled as <span class="QUOTE">"referer"</span>.)</p>
3591 <dt>Example usage:</dt>
3594 <table border="0" bgcolor="#E0E0E0" width="90%">
3597 <pre class="SCREEN">
3598 +hide-referrer{forge}
3604 <table border="0" bgcolor="#E0E0E0" width="90%">
3607 <pre class="SCREEN">
3608 +hide-referrer{http://www.yahoo.com/}
3619 <h4 class="SECT3"><a name="HIDE-USER-AGENT" id=
3620 "HIDE-USER-AGENT">8.5.26. hide-user-agent</a></h4>
3622 <div class="VARIABLELIST">
3624 <dt>Typical use:</dt>
3627 <p>Try to conceal your type of browser and client operating
3634 <p>Replaces the value of the <span class=
3635 "QUOTE">"User-Agent:"</span> HTTP header in client requests
3636 with the specified value.</p>
3642 <p>Parameterized.</p>
3648 <p>Any user-defined string.</p>
3654 <div class="WARNING">
3655 <table class="WARNING" border="1" width="90%">
3657 <td align="center"><b>Warning</b></td>
3662 <p>This can lead to problems on web sites that depend
3663 on looking at this header in order to customize their
3664 content for different browsers (which, by the way, is
3665 <span class="emphasis"><i class=
3666 "EMPHASIS">NOT</i></span> the right thing to do: good
3667 web sites work browser-independently).</p>
3673 <p>Using this action in multi-user setups or wherever different
3674 types of browsers will access the same <span class=
3675 "APPLICATION">Privoxy</span> is <span class=
3676 "emphasis"><i class="EMPHASIS">not recommended</i></span>. In
3677 single-user, single-browser setups, you might use it to delete
3678 your OS version information from the headers, because it is an
3679 invitation to exploit known bugs for your OS. It is also
3680 occasionally useful to forge this in order to access sites that
3681 won't let you in otherwise (though there may be a good reason
3684 <p>More information on known user-agent strings can be found at
3685 <a href="http://www.user-agents.org/" target=
3686 "_top">http://www.user-agents.org/</a> and <a href=
3687 "http://en.wikipedia.org/wiki/User_agent" target=
3688 "_top">http://en.wikipedia.org/wiki/User_agent</a>.</p>
3691 <dt>Example usage:</dt>
3694 <table border="0" bgcolor="#E0E0E0" width="90%">
3697 <pre class="SCREEN">
3698 +hide-user-agent{Netscape 6.1 (X11; I; Linux 2.4.18 i686)}
3709 <h4 class="SECT3"><a name="LIMIT-CONNECT" id="LIMIT-CONNECT">8.5.27.
3710 limit-connect</a></h4>
3712 <div class="VARIABLELIST">
3714 <dt>Typical use:</dt>
3717 <p>Prevent abuse of <span class="APPLICATION">Privoxy</span> as
3718 a TCP proxy relay or disable SSL for untrusted sites</p>
3724 <p>Specifies to which ports HTTP CONNECT requests are
3731 <p>Parameterized.</p>
3737 <p>A comma-separated list of ports or port ranges (the latter
3738 using dashes, with the minimum defaulting to 0 and the maximum
3745 <p>By default, i.e. if no <tt class=
3746 "LITERAL">limit-connect</tt> action applies, <span class=
3747 "APPLICATION">Privoxy</span> allows HTTP CONNECT requests to
3748 all ports. Use <tt class="LITERAL">limit-connect</tt> if
3749 fine-grained control is desired for some or all
3752 <p>The CONNECT methods exists in HTTP to allow access to secure
3753 websites (<span class="QUOTE">"https://"</span> URLs) through
3754 proxies. It works very simply: the proxy connects to the server
3755 on the specified port, and then short-circuits its connections
3756 to the client and to the remote server. This means
3757 CONNECT-enabled proxies can be used as TCP relays very
3760 <p><span class="APPLICATION">Privoxy</span> relays HTTPS
3761 traffic without seeing the decoded content. Websites can
3762 leverage this limitation to circumvent <span class=
3763 "APPLICATION">Privoxy</span>'s filters. By specifying an
3764 invalid port range you can disable HTTPS entirely.</p>
3767 <dt>Example usages:</dt>
3770 <table border="0" bgcolor="#E0E0E0" width="90%">
3773 <pre class="SCREEN">
3774 +limit-connect{443} # Port 443 is OK.
3775 +limit-connect{80,443} # Ports 80 and 443 are OK.
3776 +limit-connect{-3, 7, 20-100, 500-} # Ports less than 3, 7, 20 to 100 and above 500 are OK.
3777 +limit-connect{-} # All ports are OK
3778 +limit-connect{,} # No HTTPS/SSL traffic is allowed
3789 <h4 class="SECT3"><a name="LIMIT-COOKIE-LIFETIME" id=
3790 "LIMIT-COOKIE-LIFETIME">8.5.28. limit-cookie-lifetime</a></h4>
3792 <div class="VARIABLELIST">
3794 <dt>Typical use:</dt>
3797 <p>Limit the lifetime of HTTP cookies to a couple of minutes or
3804 <p>Overwrites the expires field in Set-Cookie server headers if
3805 it's above the specified limit.</p>
3811 <p>Parameterized.</p>
3817 <p>The lifetime limit in minutes, or 0.</p>
3823 <p>This action reduces the lifetime of HTTP cookies coming from
3824 the server to the specified number of minutes, starting from
3825 the time the cookie passes Privoxy.</p>
3827 <p>Cookies with a lifetime below the limit are not modified.
3828 The lifetime of session cookies is set to the specified
3831 <p>The effect of this action depends on the server.</p>
3833 <p>In case of servers which refresh their cookies with each
3834 response (or at least frequently), the lifetime limit set by
3835 this action is updated as well. Thus, a session associated with
3836 the cookie continues to work with this action enabled, as long
3837 as a new request is made before the last limit set is
3840 <p>However, some servers send their cookies once, with a
3841 lifetime of several years (the year 2037 is a popular choice),
3842 and do not refresh them until a certain event in the future,
3843 for example the user logging out. In this case this action may
3844 limit the absolute lifetime of the session, even if requests
3845 are made frequently.</p>
3847 <p>If the parameter is <span class="QUOTE">"0"</span>, this
3848 action behaves like <tt class="LITERAL"><a href=
3849 "actions-file.html#SESSION-COOKIES-ONLY">session-cookies-only</a></tt>.</p>
3852 <dt>Example usages:</dt>
3855 <table border="0" bgcolor="#E0E0E0" width="90%">
3858 <pre class="SCREEN">
3859 +limit-cookie-lifetime{60}
3871 <h4 class="SECT3"><a name="PREVENT-COMPRESSION" id=
3872 "PREVENT-COMPRESSION">8.5.29. prevent-compression</a></h4>
3874 <div class="VARIABLELIST">
3876 <dt>Typical use:</dt>
3879 <p>Ensure that servers send the content uncompressed, so it can
3880 be passed through <tt class="LITERAL"><a href=
3881 "actions-file.html#FILTER">filter</a></tt>s.</p>
3887 <p>Removes the Accept-Encoding header which can be used to ask
3888 for compressed transfer.</p>
3906 <p>More and more websites send their content compressed by
3907 default, which is generally a good idea and saves bandwidth.
3908 But the <tt class="LITERAL"><a href=
3909 "actions-file.html#FILTER">filter</a></tt> and <tt class=
3911 "actions-file.html#DEANIMATE-GIFS">deanimate-gifs</a></tt>
3912 actions need access to the uncompressed data.</p>
3914 <p>When compiled with zlib support (available since
3915 <span class="APPLICATION">Privoxy</span> 3.0.7), content that
3916 should be filtered is decompressed on-the-fly and you don't
3917 have to worry about this action. If you are using an older
3918 <span class="APPLICATION">Privoxy</span> version, or one that
3919 hasn't been compiled with zlib support, this action can be used
3920 to convince the server to send the content uncompressed.</p>
3922 <p>Most text-based instances compress very well, the size is
3923 seldom decreased by less than 50%, for markup-heavy instances
3924 like news feeds saving more than 90% of the original size isn't
3927 <p>Not using compression will therefore slow down the transfer,
3928 and you should only enable this action if you really need it.
3929 As of <span class="APPLICATION">Privoxy</span> 3.0.7 it's
3930 disabled in all predefined action settings.</p>
3932 <p>Note that some (rare) ill-configured sites don't handle
3933 requests for uncompressed documents correctly. Broken PHP
3934 applications tend to send an empty document body, some IIS
3935 versions only send the beginning of the content. If you enable
3936 <tt class="LITERAL">prevent-compression</tt> per default, you
3937 might want to add exceptions for those sites. See the example
3938 for how to do that.</p>
3941 <dt>Example usage (sections):</dt>
3944 <table border="0" bgcolor="#E0E0E0" width="90%">
3947 <pre class="SCREEN">
3948 # Selectively turn off compression, and enable a filter
3950 { +filter{tiny-textforms} +prevent-compression }
3951 # Match only these sites
3956 # Or instead, we could set a universal default:
3958 { +prevent-compression }
3961 # Then maybe make exceptions for broken sites:
3963 { -prevent-compression }
3975 <h4 class="SECT3"><a name="OVERWRITE-LAST-MODIFIED" id=
3976 "OVERWRITE-LAST-MODIFIED">8.5.30. overwrite-last-modified</a></h4>
3978 <div class="VARIABLELIST">
3980 <dt>Typical use:</dt>
3983 <p>Prevent yet another way to track the user's steps between
3990 <p>Deletes the <span class="QUOTE">"Last-Modified:"</span> HTTP
3991 server header or modifies its value.</p>
3997 <p>Parameterized.</p>
4003 <p>One of the keywords: <span class="QUOTE">"block"</span>,
4004 <span class="QUOTE">"reset-to-request-time"</span> and
4005 <span class="QUOTE">"randomize"</span></p>
4011 <p>Removing the <span class="QUOTE">"Last-Modified:"</span>
4012 header is useful for filter testing, where you want to force a
4013 real reload instead of getting status code <span class=
4014 "QUOTE">"304"</span>, which would cause the browser to reuse
4015 the old version of the page.</p>
4017 <p>The <span class="QUOTE">"randomize"</span> option overwrites
4018 the value of the <span class="QUOTE">"Last-Modified:"</span>
4019 header with a randomly chosen time between the original value
4020 and the current time. In theory the server could send each
4021 document with a different <span class=
4022 "QUOTE">"Last-Modified:"</span> header to track visits without
4023 using cookies. <span class="QUOTE">"Randomize"</span> makes it
4024 impossible and the browser can still revalidate cached
4027 <p><span class="QUOTE">"reset-to-request-time"</span>
4028 overwrites the value of the <span class=
4029 "QUOTE">"Last-Modified:"</span> header with the current time.
4030 You could use this option together with <tt class=
4032 "actions-file.html#HIDE-IF-MODIFIED-SINCE">hide-if-modified-since</a></tt>
4033 to further customize your random range.</p>
4035 <p>The preferred parameter here is <span class=
4036 "QUOTE">"randomize"</span>. It is safe to use, as long as the
4037 time settings are more or less correct. If the server sets the
4038 <span class="QUOTE">"Last-Modified:"</span> header to the time
4039 of the request, the random range becomes zero and the value
4040 stays the same. Therefore you should later randomize it a
4041 second time with <tt class="LITERAL"><a href=
4042 "actions-file.html#HIDE-IF-MODIFIED-SINCE">hided-if-modified-since</a></tt>,
4043 just to be sure.</p>
4045 <p>It is also recommended to use this action together with
4046 <tt class="LITERAL"><a href=
4047 "actions-file.html#CRUNCH-IF-NONE-MATCH">crunch-if-none-match</a></tt>.</p>
4050 <dt>Example usage:</dt>
4053 <table border="0" bgcolor="#E0E0E0" width="90%">
4056 <pre class="SCREEN">
4057 # Let the browser revalidate without being tracked across sessions
4058 { +hide-if-modified-since{-60} \
4059 +overwrite-last-modified{randomize} \
4060 +crunch-if-none-match}
4072 <h4 class="SECT3"><a name="REDIRECT" id="REDIRECT">8.5.31.
4075 <div class="VARIABLELIST">
4077 <dt>Typical use:</dt>
4080 <p>Redirect requests to other sites.</p>
4086 <p>Convinces the browser that the requested document has been
4087 moved to another location and the browser should get it from
4094 <p>Parameterized</p>
4100 <p>An absolute URL or a single pcrs command.</p>
4106 <p>Requests to which this action applies are answered with a
4107 HTTP redirect to URLs of your choosing. The new URL is either
4108 provided as parameter, or derived by applying a single pcrs
4109 command to the original URL.</p>
4111 <p>The syntax for pcrs commands is documented in the <a href=
4112 "filter-file.html">filter file</a> section.</p>
4114 <p>Requests can't be blocked and redirected at the same time,
4115 applying this action together with <tt class="LITERAL"><a href=
4116 "actions-file.html#BLOCK">block</a></tt> is a configuration
4117 error. Currently the request is blocked and an error message
4118 logged, the behavior may change in the future and result in
4119 Privoxy rejecting the action file.</p>
4121 <p>This action can be combined with <tt class=
4122 "LITERAL"><a href="actions-file.html#FAST-REDIRECTS">fast-redirects{check-decoded-url}</a></tt>
4123 to redirect to a decoded version of a rewritten URL.</p>
4125 <p>Use this action carefully, make sure not to create
4126 redirection loops and be aware that using your own redirects
4127 might make it possible to fingerprint your requests.</p>
4129 <p>In case of problems with your redirects, or simply to watch
4130 them working, enable <a href="config.html#DEBUG">debug
4134 <dt>Example usages:</dt>
4137 <table border="0" bgcolor="#E0E0E0" width="90%">
4140 <pre class="SCREEN">
4141 # Replace example.com's style sheet with another one
4142 { +redirect{http://localhost/css-replacements/example.com.css} }
4143 example.com/stylesheet\.css
4145 # Create a short, easy to remember nickname for a favorite site
4146 # (relies on the browser to accept and forward invalid URLs to <span class=
4147 "APPLICATION">Privoxy</span>)
4148 { +redirect{http://www.privoxy.org/user-manual/actions-file.html} }
4151 # Always use the expanded view for Undeadly.org articles
4152 # (Note the $ at the end of the URL pattern to make sure
4153 # the request for the rewritten URL isn't redirected as well)
4154 {+redirect{s@$@&mode=expanded@}}
4155 undeadly.org/cgi\?action=article&sid=\d*$
4157 # Redirect Google search requests to MSN
4158 {+redirect{s@^http://[^/]*/search\?q=([^&]*).*@http://search.msn.com/results.aspx?q=$1@}}
4161 # Redirect MSN search requests to Yahoo
4162 {+redirect{s@^http://[^/]*/results\.aspx\?q=([^&]*).*@http://search.yahoo.com/search?p=$1@}}
4163 search.msn.com//results\.aspx\?q=
4165 # Redirect http://example.com/&bla=fasel&toChange=foo (and any other value but "bar")
4166 # to http://example.com/&bla=fasel&toChange=bar
4168 # The URL pattern makes sure that the following request isn't redirected again.
4169 {+redirect{s@toChange=[^&]+@toChange=bar@}}
4170 example.com/.*toChange=(?!bar)
4172 # Add a shortcut to look up illumos bugs
4173 {+redirect{s@^http://i([0-9]+)/.*@https://www.illumos.org/issues/$1@}}
4174 # Redirected URL = http://i4974/
4175 # Redirect Destination = https://www.illumos.org/issues/4974
4176 i[0-9][0-9][0-9][0-9]*/
4178 # Redirect remote requests for this manual
4179 # to the local version delivered by Privoxy
4180 {+redirect{s@^http://www@http://config@}}
4181 www.privoxy.org/user-manual/
4192 <h4 class="SECT3"><a name="SERVER-HEADER-FILTER" id=
4193 "SERVER-HEADER-FILTER">8.5.32. server-header-filter</a></h4>
4195 <div class="VARIABLELIST">
4197 <dt>Typical use:</dt>
4200 <p>Rewrite or remove single server headers.</p>
4206 <p>All server headers to which this action applies are filtered
4207 on-the-fly through the specified regular expression based
4220 <p>The name of a server-header filter, as defined in one of the
4221 <a href="filter-file.html">filter files</a>.</p>
4227 <p>Server-header filters are applied to each header on its own,
4228 not to all at once. This makes it easier to diagnose problems,
4229 but on the downside you can't write filters that only change
4230 header x if header y's value is z. You can do that by using
4233 <p>Server-header filters are executed after the other header
4234 actions have finished and use their output as input.</p>
4236 <p>Please refer to the <a href="filter-file.html">filter file
4237 chapter</a> to learn which server-header filters are available
4238 by default, and how to create your own.</p>
4241 <dt>Example usage (section):</dt>
4244 <table border="0" bgcolor="#E0E0E0" width="90%">
4247 <pre class="SCREEN">
4248 {+server-header-filter{html-to-xml}}
4249 example.org/xml-instance-that-is-delivered-as-html
4251 {+server-header-filter{xml-to-html}}
4252 example.org/instance-that-is-delivered-as-xml-but-is-not
4264 <h4 class="SECT3"><a name="SERVER-HEADER-TAGGER" id=
4265 "SERVER-HEADER-TAGGER">8.5.33. server-header-tagger</a></h4>
4267 <div class="VARIABLELIST">
4269 <dt>Typical use:</dt>
4272 <p>Enable or disable filters based on the Content-Type
4279 <p>Server headers to which this action applies are filtered
4280 on-the-fly through the specified regular expression based
4281 substitutions, the result is used as tag.</p>
4293 <p>The name of a server-header tagger, as defined in one of the
4294 <a href="filter-file.html">filter files</a>.</p>
4300 <p>Server-header taggers are applied to each header on its own,
4301 and as the header isn't modified, each tagger <span class=
4302 "QUOTE">"sees"</span> the original.</p>
4304 <p>Server-header taggers are executed before all other header
4305 actions that modify server headers. Their tags can be used to
4306 control all of the other server-header actions, the content
4307 filters and the crunch actions (<a href=
4308 "actions-file.html#REDIRECT">redirect</a> and <a href=
4309 "actions-file.html#BLOCK">block</a>).</p>
4311 <p>Obviously crunching based on tags created by server-header
4312 taggers doesn't prevent the request from showing up in the
4313 server's log file.</p>
4316 <dt>Example usage (section):</dt>
4319 <table border="0" bgcolor="#E0E0E0" width="90%">
4322 <pre class="SCREEN">
4323 # Tag every request with the content type declared by the server
4324 {+server-header-tagger{content-type}}
4327 # If the response has a tag starting with 'image/' enable an external
4328 # filter that only applies to images.
4330 # Note that the filter is not available by default, it's just a
4331 # <tt class="LITERAL"><a href=
4332 "filter-file.html#EXTERNAL-FILTER-SYNTAX">silly example</a></tt>.
4333 {+external-filter{rotate-image} +force-text-mode}
4346 <h4 class="SECT3"><a name="SESSION-COOKIES-ONLY" id=
4347 "SESSION-COOKIES-ONLY">8.5.34. session-cookies-only</a></h4>
4349 <div class="VARIABLELIST">
4351 <dt>Typical use:</dt>
4354 <p>Allow only temporary <span class="QUOTE">"session"</span>
4355 cookies (for the current browser session <span class=
4356 "emphasis"><i class="EMPHASIS">only</i></span>).</p>
4362 <p>Deletes the <span class="QUOTE">"expires"</span> field from
4363 <span class="QUOTE">"Set-Cookie:"</span> server headers. Most
4364 browsers will not store such cookies permanently and forget
4365 them in between sessions.</p>
4383 <p>This is less strict than <tt class="LITERAL"><a href=
4384 "actions-file.html#CRUNCH-INCOMING-COOKIES">crunch-incoming-cookies</a></tt>
4385 / <tt class="LITERAL"><a href=
4386 "actions-file.html#CRUNCH-OUTGOING-COOKIES">crunch-outgoing-cookies</a></tt>
4387 and allows you to browse websites that insist or rely on
4388 setting cookies, without compromising your privacy too
4391 <p>Most browsers will not permanently store cookies that have
4392 been processed by <tt class="LITERAL">session-cookies-only</tt>
4393 and will forget about them between sessions. This makes
4394 profiling cookies useless, but won't break sites which require
4395 cookies so that you can log in for transactions. This is
4396 generally turned on for all sites, and is the recommended
4399 <p>It makes <span class="emphasis"><i class="EMPHASIS">no sense
4400 at all</i></span> to use <tt class=
4401 "LITERAL">session-cookies-only</tt> together with <tt class=
4403 "actions-file.html#CRUNCH-INCOMING-COOKIES">crunch-incoming-cookies</a></tt>
4404 or <tt class="LITERAL"><a href=
4405 "actions-file.html#CRUNCH-OUTGOING-COOKIES">crunch-outgoing-cookies</a></tt>.
4406 If you do, cookies will be plainly killed.</p>
4408 <p>Note that it is up to the browser how it handles such
4409 cookies without an <span class="QUOTE">"expires"</span> field.
4410 If you use an exotic browser, you might want to try it out to
4413 <p>This setting also has no effect on cookies that may have
4414 been stored previously by the browser before starting
4415 <span class="APPLICATION">Privoxy</span>. These would have to
4416 be removed manually.</p>
4418 <p><span class="APPLICATION">Privoxy</span> also uses the
4420 "actions-file.html#FILTER-CONTENT-COOKIES">content-cookies
4421 filter</a> to block some types of cookies. Content cookies are
4422 not effected by <tt class=
4423 "LITERAL">session-cookies-only</tt>.</p>
4426 <dt>Example usage:</dt>
4429 <table border="0" bgcolor="#E0E0E0" width="90%">
4432 <pre class="SCREEN">
4433 +session-cookies-only
4444 <h4 class="SECT3"><a name="SET-IMAGE-BLOCKER" id=
4445 "SET-IMAGE-BLOCKER">8.5.35. set-image-blocker</a></h4>
4447 <div class="VARIABLELIST">
4449 <dt>Typical use:</dt>
4452 <p>Choose the replacement for blocked images</p>
4458 <p>This action alone doesn't do anything noticeable. If
4459 <span class="emphasis"><i class="EMPHASIS">both</i></span>
4460 <tt class="LITERAL"><a href=
4461 "actions-file.html#BLOCK">block</a></tt> <span class=
4462 "emphasis"><i class="EMPHASIS">and</i></span> <tt class=
4464 "actions-file.html#HANDLE-AS-IMAGE">handle-as-image</a></tt>
4465 <span class="emphasis"><i class="EMPHASIS">also</i></span>
4466 apply, i.e. if the request is to be blocked as an image,
4467 <span class="emphasis"><i class="EMPHASIS">then</i></span> the
4468 parameter of this action decides what will be sent as a
4475 <p>Parameterized.</p>
4483 <p><span class="QUOTE">"pattern"</span> to send a built-in
4484 checkerboard pattern image. The image is visually decent,
4485 scales very well, and makes it obvious where banners were
4490 <p><span class="QUOTE">"blank"</span> to send a built-in
4491 transparent image. This makes banners disappear completely,
4492 but makes it hard to detect where <span class=
4493 "APPLICATION">Privoxy</span> has blocked images on a given
4494 page and complicates troubleshooting if <span class=
4495 "APPLICATION">Privoxy</span> has blocked innocent images,
4496 like navigation icons.</p>
4500 <p><span class="QUOTE">"<tt class=
4501 "REPLACEABLE"><i>target-url</i></tt>"</span> to send a
4502 redirect to <tt class="REPLACEABLE"><i>target-url</i></tt>.
4503 You can redirect to any image anywhere, even in your local
4504 filesystem via <span class="QUOTE">"file:///"</span> URL.
4505 (But note that not all browsers support redirecting to a
4506 local file system).</p>
4508 <p>A good application of redirects is to use special
4509 <span class="APPLICATION">Privoxy</span>-built-in URLs,
4510 which send the built-in images, as <tt class=
4511 "REPLACEABLE"><i>target-url</i></tt>. This has the same
4512 visual effect as specifying <span class=
4513 "QUOTE">"blank"</span> or <span class=
4514 "QUOTE">"pattern"</span> in the first place, but enables
4515 your browser to cache the replacement image, instead of
4516 requesting it over and over again.</p>
4524 <p>The URLs for the built-in images are <span class=
4525 "QUOTE">"http://config.privoxy.org/send-banner?type=<tt class=
4526 "REPLACEABLE"><i>type</i></tt>"</span>, where <tt class=
4527 "REPLACEABLE"><i>type</i></tt> is either <span class=
4528 "QUOTE">"blank"</span> or <span class=
4529 "QUOTE">"pattern"</span>.</p>
4531 <p>There is a third (advanced) type, called <span class=
4532 "QUOTE">"auto"</span>. It is <span class="emphasis"><i class=
4533 "EMPHASIS">NOT</i></span> to be used in <tt class=
4534 "LITERAL">set-image-blocker</tt>, but meant for use from
4535 <a href="filter-file.html">filters</a>. Auto will select the
4536 type of image that would have applied to the referring page,
4537 had it been an image.</p>
4540 <dt>Example usage:</dt>
4543 <p>Built-in pattern:</p>
4545 <table border="0" bgcolor="#E0E0E0" width="90%">
4548 <pre class="SCREEN">
4549 +set-image-blocker{pattern}
4555 <p>Redirect to the BSD daemon:</p>
4557 <table border="0" bgcolor="#E0E0E0" width="90%">
4560 <pre class="SCREEN">
4561 +set-image-blocker{http://www.freebsd.org/gifs/dae_up3.gif}
4567 <p>Redirect to the built-in pattern for better caching:</p>
4569 <table border="0" bgcolor="#E0E0E0" width="90%">
4572 <pre class="SCREEN">
4573 +set-image-blocker{http://config.privoxy.org/send-banner?type=pattern}
4584 <h3 class="SECT3"><a name="SUMMARY" id="SUMMARY">8.5.36.
4587 <p>Note that many of these actions have the potential to cause a page
4588 to misbehave, possibly even not to display at all. There are many
4589 ways a site designer may choose to design his site, and what HTTP
4590 header content, and other criteria, he may depend on. There is no way
4591 to have hard and fast rules for all sites. See the <a href=
4592 "appendix.html#ACTIONSANAT">Appendix</a> for a brief example on
4593 troubleshooting actions.</p>
4598 <h2 class="SECT2"><a name="ALIASES" id="ALIASES">8.6. Aliases</a></h2>
4600 <p>Custom <span class="QUOTE">"actions"</span>, known to <span class=
4601 "APPLICATION">Privoxy</span> as <span class="QUOTE">"aliases"</span>,
4602 can be defined by combining other actions. These can in turn be invoked
4603 just like the built-in actions. Currently, an alias name can contain
4604 any character except space, tab, <span class="QUOTE">"="</span>,
4605 <span class="QUOTE">"{"</span> and <span class="QUOTE">"}"</span>, but
4606 we <span class="emphasis"><i class="EMPHASIS">strongly
4607 recommend</i></span> that you only use <span class="QUOTE">"a"</span>
4608 to <span class="QUOTE">"z"</span>, <span class="QUOTE">"0"</span> to
4609 <span class="QUOTE">"9"</span>, <span class="QUOTE">"+"</span>, and
4610 <span class="QUOTE">"-"</span>. Alias names are not case sensitive, and
4611 are not required to start with a <span class="QUOTE">"+"</span> or
4612 <span class="QUOTE">"-"</span> sign, since they are merely textually
4615 <p>Aliases can be used throughout the actions file, but they
4616 <span class="emphasis"><i class="EMPHASIS">must be defined in a special
4617 section at the top of the file!</i></span> And there can only be one
4618 such section per actions file. Each actions file may have its own alias
4619 section, and the aliases defined in it are only visible within that
4622 <p>There are two main reasons to use aliases: One is to save typing for
4623 frequently used combinations of actions, the other one is a gain in
4624 flexibility: If you decide once how you want to handle shops by
4625 defining an alias called <span class="QUOTE">"shop"</span>, you can
4626 later change your policy on shops in <span class="emphasis"><i class=
4627 "EMPHASIS">one</i></span> place, and your changes will take effect
4628 everywhere in the actions file where the <span class=
4629 "QUOTE">"shop"</span> alias is used. Calling aliases by their purpose
4630 also makes your actions files more readable.</p>
4632 <p>Currently, there is one big drawback to using aliases, though:
4633 <span class="APPLICATION">Privoxy</span>'s built-in web-based action
4634 file editor honors aliases when reading the actions files, but it
4635 expands them before writing. So the effects of your aliases are of
4636 course preserved, but the aliases themselves are lost when you edit
4637 sections that use aliases with it.</p>
4639 <p>Now let's define some aliases...</p>
4641 <table border="0" bgcolor="#E0E0E0" width="100%">
4644 <pre class="SCREEN">
4645 # Useful custom aliases we can use later.
4647 # Note the (required!) section header line and that this section
4648 # must be at the top of the actions file!
4652 # These aliases just save typing later:
4653 # (Note that some already use other aliases!)
4655 +crunch-all-cookies = +<a href=
4656 "actions-file.html#CRUNCH-INCOMING-COOKIES">crunch-incoming-cookies</a> +<a href="actions-file.html#CRUNCH-OUTGOING-COOKIES">crunch-outgoing-cookies</a>
4657 -crunch-all-cookies = -<a href=
4658 "actions-file.html#CRUNCH-INCOMING-COOKIES">crunch-incoming-cookies</a> -<a href="actions-file.html#CRUNCH-OUTGOING-COOKIES">crunch-outgoing-cookies</a>
4659 +block-as-image = +block{Blocked image.} +handle-as-image
4660 allow-all-cookies = -crunch-all-cookies -<a href=
4661 "actions-file.html#SESSION-COOKIES-ONLY">session-cookies-only</a> -<a href=
4662 "actions-file.html#FILTER-CONTENT-COOKIES">filter{content-cookies}</a>
4664 # These aliases define combinations of actions
4665 # that are useful for certain types of sites:
4667 fragile = -<a href="actions-file.html#BLOCK">block</a> -<a href=
4668 "actions-file.html#FILTER">filter</a> -crunch-all-cookies -<a href=
4669 "actions-file.html#FAST-REDIRECTS">fast-redirects</a> -<a href=
4670 "actions-file.html#HIDE-REFERER">hide-referrer</a> -<a href=
4671 "actions-file.html#PREVENT-COMPRESSION">prevent-compression</a>
4673 shop = -crunch-all-cookies -<a href=
4674 "actions-file.html#FILTER-ALL-POPUPS">filter{all-popups}</a>
4676 # Short names for other aliases, for really lazy people ;-)
4678 c0 = +crunch-all-cookies
4679 c1 = -crunch-all-cookies
4685 <p>...and put them to use. These sections would appear in the lower
4686 part of an actions file and define exceptions to the default actions
4687 (as specified further up for the <span class="QUOTE">"/"</span>
4690 <table border="0" bgcolor="#E0E0E0" width="100%">
4693 <pre class="SCREEN">
4694 # These sites are either very complex or very keen on
4695 # user data and require minimal interference to work:
4698 .office.microsoft.com
4699 .windowsupdate.microsoft.com
4700 # Gmail is really mail.google.com, not gmail.com
4704 # Allow cookies (for setting and retrieving your customer data)
4708 .worldpay.com # for quietpc.com
4711 # These shops require pop-ups:
4713 {-filter{all-popups} -filter{unsolicited-popups}}
4721 <p>Aliases like <span class="QUOTE">"shop"</span> and <span class=
4722 "QUOTE">"fragile"</span> are typically used for <span class=
4723 "QUOTE">"problem"</span> sites that require more than one action to be
4724 disabled in order to function properly.</p>
4728 <h2 class="SECT2"><a name="ACT-EXAMPLES" id="ACT-EXAMPLES">8.7. Actions
4729 Files Tutorial</a></h2>
4731 <p>The above chapters have shown <a href="actions-file.html">which
4732 actions files there are and how they are organized</a>, how actions are
4733 <a href="actions-file.html#ACTIONS">specified</a> and <a href=
4734 "actions-file.html#ACTIONS-APPLY">applied to URLs</a>, how <a href=
4735 "actions-file.html#AF-PATTERNS">patterns</a> work, and how to define
4736 and use <a href="actions-file.html#ALIASES">aliases</a>. Now, let's
4737 look at an example <tt class="FILENAME">match-all.action</tt>,
4738 <tt class="FILENAME">default.action</tt> and <tt class=
4739 "FILENAME">user.action</tt> file and see how all these pieces come
4743 <h3 class="SECT3"><a name="MATCH-ALL" id="MATCH-ALL">8.7.1.
4744 match-all.action</a></h3>
4746 <p>Remember <span class="emphasis"><i class="EMPHASIS">all actions
4747 are disabled when matching starts</i></span>, so we have to
4748 explicitly enable the ones we want.</p>
4750 <p>While the <tt class="FILENAME">match-all.action</tt> file only
4751 contains a single section, it is probably the most important one. It
4752 has only one pattern, <span class="QUOTE">"<tt class=
4753 "LITERAL">/</tt>"</span>, but this pattern <a href=
4754 "actions-file.html#AF-PATTERNS">matches all URLs</a>. Therefore, the
4755 set of actions used in this <span class="QUOTE">"default"</span>
4756 section <span class="emphasis"><i class="EMPHASIS">will be applied to
4757 all requests as a start</i></span>. It can be partly or wholly
4758 overridden by other actions files like <tt class=
4759 "FILENAME">default.action</tt> and <tt class=
4760 "FILENAME">user.action</tt>, but it will still be largely responsible
4761 for your overall browsing experience.</p>
4763 <p>Again, at the start of matching, all actions are disabled, so
4764 there is no need to disable any actions here. (Remember: a
4765 <span class="QUOTE">"+"</span> preceding the action name enables the
4766 action, a <span class="QUOTE">"-"</span> disables!). Also note how
4767 this long line has been made more readable by splitting it into
4768 multiple lines with line continuation.</p>
4770 <table border="0" bgcolor="#E0E0E0" width="100%">
4773 <pre class="SCREEN">
4776 "actions-file.html#CHANGE-X-FORWARDED-FOR">change-x-forwarded-for{block}</a> \
4777 +<a href="actions-file.html#HIDE-FROM-HEADER">hide-from-header{block}</a> \
4779 "actions-file.html#SET-IMAGE-BLOCKER">set-image-blocker{pattern}</a> \
4788 <p>The default behavior is now set.</p>
4792 <h3 class="SECT3"><a name="DEFAULT-ACTION" id="DEFAULT-ACTION">8.7.2.
4793 default.action</a></h3>
4795 <p>If you aren't a developer, there's no need for you to edit the
4796 <tt class="FILENAME">default.action</tt> file. It is maintained by
4797 the <span class="APPLICATION">Privoxy</span> developers and if you
4798 disagree with some of the sections, you should overrule them in your
4799 <tt class="FILENAME">user.action</tt>.</p>
4801 <p>Understanding the <tt class="FILENAME">default.action</tt> file
4802 can help you with your <tt class="FILENAME">user.action</tt>,
4805 <p>The first section in this file is a special section for internal
4806 use that prevents older <span class="APPLICATION">Privoxy</span>
4807 versions from reading the file:</p>
4809 <table border="0" bgcolor="#E0E0E0" width="100%">
4812 <pre class="SCREEN">
4813 ##########################################################################
4814 # Settings -- Don't change! For internal Privoxy use ONLY.
4815 ##########################################################################
4817 for-privoxy-version=3.0.11
4823 <p>After that comes the (optional) alias section. We'll use the
4824 example section from the above <a href=
4825 "actions-file.html#ALIASES">chapter on aliases</a>, that also
4826 explains why and how aliases are used:</p>
4828 <table border="0" bgcolor="#E0E0E0" width="100%">
4831 <pre class="SCREEN">
4832 ##########################################################################
4834 ##########################################################################
4837 # These aliases just save typing later:
4838 # (Note that some already use other aliases!)
4840 +crunch-all-cookies = +<a href=
4841 "actions-file.html#CRUNCH-INCOMING-COOKIES">crunch-incoming-cookies</a> +<a href="actions-file.html#CRUNCH-OUTGOING-COOKIES">crunch-outgoing-cookies</a>
4842 -crunch-all-cookies = -<a href=
4843 "actions-file.html#CRUNCH-INCOMING-COOKIES">crunch-incoming-cookies</a> -<a href="actions-file.html#CRUNCH-OUTGOING-COOKIES">crunch-outgoing-cookies</a>
4844 +block-as-image = +block{Blocked image.} +handle-as-image
4845 mercy-for-cookies = -crunch-all-cookies -<a href=
4846 "actions-file.html#SESSION-COOKIES-ONLY">session-cookies-only</a> -<a href=
4847 "actions-file.html#FILTER-CONTENT-COOKIES">filter{content-cookies}</a>
4849 # These aliases define combinations of actions
4850 # that are useful for certain types of sites:
4852 fragile = -<a href="actions-file.html#BLOCK">block</a> -<a href=
4853 "actions-file.html#FILTER">filter</a> -crunch-all-cookies -<a href=
4854 "actions-file.html#FAST-REDIRECTS">fast-redirects</a> -<a href=
4855 "actions-file.html#HIDE-REFERER">hide-referrer</a>
4856 shop = -crunch-all-cookies -<a href=
4857 "actions-file.html#FILTER-ALL-POPUPS">filter{all-popups}</a>
4863 <p>The first of our specialized sections is concerned with
4864 <span class="QUOTE">"fragile"</span> sites, i.e. sites that require
4865 minimum interference, because they are either very complex or very
4866 keen on tracking you (and have mechanisms in place that make them
4867 unusable for people who avoid being tracked). We will simply use our
4868 pre-defined <tt class="LITERAL">fragile</tt> alias instead of stating
4869 the list of actions explicitly:</p>
4871 <table border="0" bgcolor="#E0E0E0" width="100%">
4874 <pre class="SCREEN">
4875 ##########################################################################
4876 # Exceptions for sites that'll break under the default action set:
4877 ##########################################################################
4879 # "Fragile" Use a minimum set of actions for these sites (see alias above):
4882 .office.microsoft.com # surprise, surprise!
4883 .windowsupdate.microsoft.com
4890 <p>Shopping sites are not as fragile, but they typically require
4891 cookies to log in, and pop-up windows for shopping carts or item
4892 details. Again, we'll use a pre-defined alias:</p>
4894 <table border="0" bgcolor="#E0E0E0" width="100%">
4897 <pre class="SCREEN">
4902 .worldpay.com # for quietpc.com
4910 <p>The <tt class="LITERAL"><a href=
4911 "actions-file.html#FAST-REDIRECTS">fast-redirects</a></tt> action,
4912 which may have been enabled in <tt class=
4913 "FILENAME">match-all.action</tt>, breaks some sites. So disable it
4914 for popular sites where we know it misbehaves:</p>
4916 <table border="0" bgcolor="#E0E0E0" width="100%">
4919 <pre class="SCREEN">
4920 { -<a href="actions-file.html#FAST-REDIRECTS">fast-redirects</a> }
4924 .altavista.com/.*(like|url|link):http
4925 .altavista.com/trans.*urltext=http
4932 <p>It is important that <span class="APPLICATION">Privoxy</span>
4933 knows which URLs belong to images, so that <span class=
4934 "emphasis"><i class="EMPHASIS">if</i></span> they are to be blocked,
4935 a substitute image can be sent, rather than an HTML page. Contacting
4936 the remote site to find out is not an option, since it would destroy
4937 the loading time advantage of banner blocking, and it would feed the
4938 advertisers information about you. We can mark any URL as an image
4939 with the <tt class="LITERAL"><a href=
4940 "actions-file.html#HANDLE-AS-IMAGE">handle-as-image</a></tt> action,
4941 and marking all URLs that end in a known image file extension is a
4944 <table border="0" bgcolor="#E0E0E0" width="100%">
4947 <pre class="SCREEN">
4948 ##########################################################################
4950 ##########################################################################
4952 # Define which file types will be treated as images, in case they get
4953 # blocked further down this file:
4955 { +<a href="actions-file.html#HANDLE-AS-IMAGE">handle-as-image</a> }
4956 /.*\.(gif|jpe?g|png|bmp|ico)$
4962 <p>And then there are known banner sources. They often use scripts to
4963 generate the banners, so it won't be visible from the URL that the
4964 request is for an image. Hence we block them <span class=
4965 "emphasis"><i class="EMPHASIS">and</i></span> mark them as images in
4966 one go, with the help of our <tt class="LITERAL">+block-as-image</tt>
4967 alias defined above. (We could of course just as well use <tt class=
4968 "LITERAL">+<a href="actions-file.html#BLOCK">block</a> +<a href=
4969 "actions-file.html#HANDLE-AS-IMAGE">handle-as-image</a></tt> here.)
4970 Remember that the type of the replacement image is chosen by the
4971 <tt class="LITERAL"><a href=
4972 "actions-file.html#SET-IMAGE-BLOCKER">set-image-blocker</a></tt>
4973 action. Since all URLs have matched the default section with its
4974 <tt class="LITERAL">+<a href=
4975 "actions-file.html#SET-IMAGE-BLOCKER">set-image-blocker</a>{pattern}</tt>
4976 action before, it still applies and needn't be repeated:</p>
4978 <table border="0" bgcolor="#E0E0E0" width="100%">
4981 <pre class="SCREEN">
4982 # Known ad generators:
4987 .ad.*.doubleclick.net
4988 .a.yimg.com/(?:(?!/i/).)*$
4989 .a[0-9].yimg.com/(?:(?!/i/).)*$
4997 <p>One of the most important jobs of <span class=
4998 "APPLICATION">Privoxy</span> is to block banners. Many of these can
4999 be <span class="QUOTE">"blocked"</span> by the <tt class=
5001 "actions-file.html#FILTER">filter</a>{banners-by-size}</tt> action,
5002 which we enabled above, and which deletes the references to banner
5003 images from the pages while they are loaded, so the browser doesn't
5004 request them anymore, and hence they don't need to be blocked here.
5005 But this naturally doesn't catch all banners, and some people choose
5006 not to use filters, so we need a comprehensive list of patterns for
5007 banner URLs here, and apply the <tt class="LITERAL"><a href=
5008 "actions-file.html#BLOCK">block</a></tt> action to them.</p>
5010 <p>First comes many generic patterns, which do most of the work, by
5011 matching typical domain and path name components of banners. Then
5012 comes a list of individual patterns for specific sites, which is
5013 omitted here to keep the example short:</p>
5015 <table border="0" bgcolor="#E0E0E0" width="100%">
5018 <pre class="SCREEN">
5019 ##########################################################################
5020 # Block these fine banners:
5021 ##########################################################################
5022 { <a href="actions-file.html#BLOCK">+block{Banner ads.}</a> }
5030 /.*count(er)?\.(pl|cgi|exe|dll|asp|php[34]?)
5031 /(?:.*/)?(publicite|werbung|rekla(ma|me|am)|annonse|maino(kset|nta|s)?)/
5033 # Site-specific patterns (abbreviated):
5041 <p>It's quite remarkable how many advertisers actually call their
5042 banner servers ads.<tt class="REPLACEABLE"><i>company</i></tt>.com,
5043 or call the directory in which the banners are stored simply
5044 <span class="QUOTE">"banners"</span>. So the above generic patterns
5045 are surprisingly effective.</p>
5047 <p>But being very generic, they necessarily also catch URLs that we
5048 don't want to block. The pattern <tt class="LITERAL">.*ads.</tt> e.g.
5049 catches <span class="QUOTE">"nasty-<span class="emphasis"><i class=
5050 "EMPHASIS">ads</i></span>.nasty-corp.com"</span> as intended, but
5051 also <span class="QUOTE">"downlo<span class="emphasis"><i class=
5052 "EMPHASIS">ads</i></span>.sourcefroge.net"</span> or <span class=
5053 "QUOTE">"<span class="emphasis"><i class=
5054 "EMPHASIS">ads</i></span>l.some-provider.net."</span> So here come
5055 some well-known exceptions to the <tt class="LITERAL">+<a href=
5056 "actions-file.html#BLOCK">block</a></tt> section above.</p>
5058 <p>Note that these are exceptions to exceptions from the default!
5059 Consider the URL <span class=
5060 "QUOTE">"downloads.sourcefroge.net"</span>: Initially, all actions
5061 are deactivated, so it wouldn't get blocked. Then comes the defaults
5062 section, which matches the URL, but just deactivates the <tt class=
5063 "LITERAL"><a href="actions-file.html#BLOCK">block</a></tt> action
5064 once again. Then it matches <tt class="LITERAL">.*ads.</tt>, an
5065 exception to the general non-blocking policy, and suddenly <tt class=
5066 "LITERAL"><a href="actions-file.html#BLOCK">+block</a></tt> applies.
5067 And now, it'll match <tt class="LITERAL">.*loads.</tt>, where
5068 <tt class="LITERAL"><a href="actions-file.html#BLOCK">-block</a></tt>
5069 applies, so (unless it matches <span class="emphasis"><i class=
5070 "EMPHASIS">again</i></span> further down) it ends up with no
5071 <tt class="LITERAL"><a href="actions-file.html#BLOCK">block</a></tt>
5072 action applying.</p>
5074 <table border="0" bgcolor="#E0E0E0" width="100%">
5077 <pre class="SCREEN">
5078 ##########################################################################
5079 # Save some innocent victims of the above generic block patterns:
5080 ##########################################################################
5084 { -<a href="actions-file.html#BLOCK">block</a> }
5085 adv[io]*. # (for advogato.org and advice.*)
5086 adsl. # (has nothing to do with ads)
5087 adobe. # (has nothing to do with ads either)
5088 ad[ud]*. # (adult.* and add.*)
5089 .edu # (universities don't host banners (yet!))
5090 .*loads. # (downloads, uploads etc)
5098 www.globalintersec.com/adv # (adv = advanced)
5099 www.ugu.com/sui/ugu/adv
5105 <p>Filtering source code can have nasty side effects, so make an
5106 exception for our friends at sourceforge.net, and all paths with
5107 <span class="QUOTE">"cvs"</span> in them. Note that <tt class=
5108 "LITERAL">-<a href="actions-file.html#FILTER">filter</a></tt>
5109 disables <span class="emphasis"><i class="EMPHASIS">all</i></span>
5110 filters in one fell swoop!</p>
5112 <table border="0" bgcolor="#E0E0E0" width="100%">
5115 <pre class="SCREEN">
5116 # Don't filter code!
5118 { -<a href="actions-file.html#FILTER">filter</a> }
5129 <p>The actual <tt class="FILENAME">default.action</tt> is of course
5130 much more comprehensive, but we hope this example made clear how it
5135 <h3 class="SECT3"><a name="USER-ACTION" id="USER-ACTION">8.7.3.
5136 user.action</a></h3>
5138 <p>So far we are painting with a broad brush by setting general
5139 policies, which would be a reasonable starting point for many people.
5140 Now, you might want to be more specific and have customized rules
5141 that are more suitable to your personal habits and preferences. These
5142 would be for narrowly defined situations like your ISP or your bank,
5143 and should be placed in <tt class="FILENAME">user.action</tt>, which
5144 is parsed after all other actions files and hence has the last word,
5145 over-riding any previously defined actions. <tt class=
5146 "FILENAME">user.action</tt> is also a <span class=
5147 "emphasis"><i class="EMPHASIS">safe</i></span> place for your
5148 personal settings, since <tt class="FILENAME">default.action</tt> is
5149 actively maintained by the <span class="APPLICATION">Privoxy</span>
5150 developers and you'll probably want to install updated versions from
5153 <p>So let's look at a few examples of things that one might typically
5154 do in <tt class="FILENAME">user.action</tt>:</p>
5156 <table border="0" bgcolor="#E0E0E0" width="100%">
5159 <pre class="SCREEN">
5160 # My user.action file. <fred@example.com>
5166 <p>As <a href="actions-file.html#ALIASES">aliases</a> are local to
5167 the actions file that they are defined in, you can't use the ones
5168 from <tt class="FILENAME">default.action</tt>, unless you repeat them
5171 <table border="0" bgcolor="#E0E0E0" width="100%">
5174 <pre class="SCREEN">
5175 # Aliases are local to the file they are defined in.
5176 # (Re-)define aliases for this file:
5180 # These aliases just save typing later, and the alias names should
5181 # be self explanatory.
5183 +crunch-all-cookies = +crunch-incoming-cookies +crunch-outgoing-cookies
5184 -crunch-all-cookies = -crunch-incoming-cookies -crunch-outgoing-cookies
5185 allow-all-cookies = -crunch-all-cookies -session-cookies-only
5186 allow-popups = -filter{all-popups}
5187 +block-as-image = +block{Blocked as image.} +handle-as-image
5188 -block-as-image = -block
5190 # These aliases define combinations of actions that are useful for
5191 # certain types of sites:
5193 fragile = -block -crunch-all-cookies -filter -fast-redirects -hide-referrer
5194 shop = -crunch-all-cookies allow-popups
5196 # Allow ads for selected useful free sites:
5198 allow-ads = -block -filter{banners-by-size} -filter{banners-by-link}
5200 # Alias for specific file types that are text, but might have conflicting
5201 # MIME types. We want the browser to force these to be text documents.
5202 handle-as-text = -<a href="actions-file.html#FILTER">filter</a> +-<a href=
5203 "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>
5209 <p>Say you have accounts on some sites that you visit regularly, and
5210 you don't want to have to log in manually each time. So you'd like to
5211 allow persistent cookies for these sites. The <tt class=
5212 "LITERAL">allow-all-cookies</tt> alias defined above does exactly
5213 that, i.e. it disables crunching of cookies in any direction, and the
5214 processing of cookies to make them only temporary.</p>
5216 <table border="0" bgcolor="#E0E0E0" width="100%">
5219 <pre class="SCREEN">
5220 { allow-all-cookies }
5230 <p>Your bank is allergic to some filter, but you don't know which, so
5231 you disable them all:</p>
5233 <table border="0" bgcolor="#E0E0E0" width="100%">
5236 <pre class="SCREEN">
5237 { -<a href="actions-file.html#FILTER">filter</a> }
5238 .your-home-banking-site.com
5244 <p>Some file types you may not want to filter for various
5247 <table border="0" bgcolor="#E0E0E0" width="100%">
5250 <pre class="SCREEN">
5251 # Technical documentation is likely to contain strings that might
5252 # erroneously get altered by the JavaScript-oriented filters:
5257 # And this stupid host sends streaming video with a wrong MIME type,
5258 # so that Privoxy thinks it is getting HTML and starts filtering:
5260 stupid-server.example.com/
5266 <p>Example of a simple <a href="actions-file.html#BLOCK">block</a>
5267 action. Say you've seen an ad on your favourite page on example.com
5268 that you want to get rid of. You have right-clicked the image,
5269 selected <span class="QUOTE">"copy image location"</span> and pasted
5270 the URL below while removing the leading http://, into a <tt class=
5271 "LITERAL">{ +block{} }</tt> section. Note that <tt class="LITERAL">{
5272 +handle-as-image }</tt> need not be specified, since all URLs ending
5273 in <tt class="LITERAL">.gif</tt> will be tagged as images by the
5274 general rules as set in default.action anyway:</p>
5276 <table border="0" bgcolor="#E0E0E0" width="100%">
5279 <pre class="SCREEN">
5280 { +<a href="actions-file.html#BLOCK">block</a>{Nasty ads.} }
5281 www.example.com/nasty-ads/sponsor\.gif
5282 another.example.net/more/junk/here/
5288 <p>The URLs of dynamically generated banners, especially from large
5289 banner farms, often don't use the well-known image file name
5290 extensions, which makes it impossible for <span class=
5291 "APPLICATION">Privoxy</span> to guess the file type just by looking
5292 at the URL. You can use the <tt class="LITERAL">+block-as-image</tt>
5293 alias defined above for these cases. Note that objects which match
5294 this rule but then turn out NOT to be an image are typically rendered
5295 as a <span class="QUOTE">"broken image"</span> icon by the browser.
5298 <table border="0" bgcolor="#E0E0E0" width="100%">
5301 <pre class="SCREEN">
5312 <p>Now you noticed that the default configuration breaks Forbes
5313 Magazine, but you were too lazy to find out which action is the
5314 culprit, and you were again too lazy to give <a href=
5315 "contact.html">feedback</a>, so you just used the <tt class=
5316 "LITERAL">fragile</tt> alias on the site, and -- <span class=
5317 "emphasis"><i class="EMPHASIS">whoa!</i></span> -- it worked. The
5318 <tt class="LITERAL">fragile</tt> aliases disables those actions that
5319 are most likely to break a site. Also, good for testing purposes to
5320 see if it is <span class="APPLICATION">Privoxy</span> that is causing
5321 the problem or not. We later find other regular sites that misbehave,
5322 and add those to our personalized list of troublemakers:</p>
5324 <table border="0" bgcolor="#E0E0E0" width="100%">
5327 <pre class="SCREEN">
5337 <p>You like the <span class="QUOTE">"fun"</span> text replacements in
5338 <tt class="FILENAME">default.filter</tt>, but it is disabled in the
5339 distributed actions file. So you'd like to turn it on in your
5340 private, update-safe config, once and for all:</p>
5342 <table border="0" bgcolor="#E0E0E0" width="100%">
5345 <pre class="SCREEN">
5346 { +<a href="actions-file.html#FILTER-FUN">filter{fun}</a> }
5353 <p>Note that the above is not really a good idea: There are
5354 exceptions to the filters in <tt class="FILENAME">default.action</tt>
5355 for things that really shouldn't be filtered, like code on
5356 CVS->Web interfaces. Since <tt class="FILENAME">user.action</tt>
5357 has the last word, these exceptions won't be valid for the
5358 <span class="QUOTE">"fun"</span> filtering specified here.</p>
5360 <p>You might also worry about how your favourite free websites are
5361 funded, and find that they rely on displaying banner advertisements
5362 to survive. So you might want to specifically allow banners for those
5363 sites that you feel provide value to you:</p>
5365 <table border="0" bgcolor="#E0E0E0" width="100%">
5368 <pre class="SCREEN">
5378 <p>Note that <tt class="LITERAL">allow-ads</tt> has been aliased to
5379 <tt class="LITERAL">-<a href=
5380 "actions-file.html#BLOCK">block</a></tt>, <tt class=
5382 "actions-file.html#FILTER-BANNERS-BY-SIZE">filter{banners-by-size}</a></tt>,
5383 and <tt class="LITERAL">-<a href=
5384 "actions-file.html#FILTER-BANNERS-BY-LINK">filter{banners-by-link}</a></tt>
5387 <p>Invoke another alias here to force an over-ride of the MIME type
5388 <tt class="LITERAL">application/x-sh</tt> which typically would open
5389 a download type dialog. In my case, I want to look at the shell
5390 script, and then I can save it should I choose to.</p>
5392 <table border="0" bgcolor="#E0E0E0" width="100%">
5395 <pre class="SCREEN">
5403 <p><tt class="FILENAME">user.action</tt> is generally the best place
5404 to define exceptions and additions to the default policies of
5405 <tt class="FILENAME">default.action</tt>. Some actions are safe to
5406 have their default policies set here though. So let's set a default
5407 policy to have a <span class="QUOTE">"blank"</span> image as opposed
5408 to the checkerboard pattern for <span class="emphasis"><i class=
5409 "EMPHASIS">ALL</i></span> sites. <span class="QUOTE">"/"</span> of
5410 course matches all URL paths and patterns:</p>
5412 <table border="0" bgcolor="#E0E0E0" width="100%">
5415 <pre class="SCREEN">
5417 "actions-file.html#SET-IMAGE-BLOCKER">set-image-blocker{blank}</a> }
5427 <div class="NAVFOOTER">
5428 <hr align="left" width="100%">
5430 <table summary="Footer navigation table" width="100%" border="0"
5431 cellpadding="0" cellspacing="0">
5433 <td width="33%" align="left" valign="top"><a href="config.html"
5434 accesskey="P">Prev</a></td>
5436 <td width="34%" align="center" valign="top"><a href="index.html"
5437 accesskey="H">Home</a></td>
5439 <td width="33%" align="right" valign="top"><a href="filter-file.html"
5440 accesskey="N">Next</a></td>
5444 <td width="33%" align="left" valign="top">The Main Configuration
5447 <td width="34%" align="center" valign="top"> </td>
5449 <td width="33%" align="right" valign="top">Filter Files</td>