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29 <h1 class="SECT1"><a name="ACTIONS-FILE" id="ACTIONS-FILE">8. Actions Files</a></h1>
30 <p>The actions files are used to define what <span class="emphasis"><i class="EMPHASIS">actions</i></span>
31 <span class="APPLICATION">Privoxy</span> takes for which URLs, and thus determines how ad images, cookies and
32 various other aspects of HTTP content and transactions are handled, and on which sites (or even parts thereof).
33 There are a number of such actions, with a wide range of functionality. Each action does something a little
34 different. These actions give us a veritable arsenal of tools with which to exert our control, preferences and
35 independence. Actions can be combined so that their effects are aggregated when applied against a given set of
37 <p>There are three action files included with <span class="APPLICATION">Privoxy</span> with differing purposes:</p>
40 <p><tt class="FILENAME">match-all.action</tt> - is used to define which <span class="QUOTE">"actions"</span>
41 relating to banner-blocking, images, pop-ups, content modification, cookie handling etc should be applied by
42 default. It should be the first actions file loaded</p>
45 <p><tt class="FILENAME">default.action</tt> - defines many exceptions (both positive and negative) from the
46 default set of actions that's configured in <tt class="FILENAME">match-all.action</tt>. It is a set of rules
47 that should work reasonably well as-is for most users. This file is only supposed to be edited by the
48 developers. It should be the second actions file loaded.</p>
51 <p><tt class="FILENAME">user.action</tt> - is intended to be for local site preferences and exceptions. As an
52 example, if your ISP or your bank has specific requirements, and need special handling, this kind of thing
53 should go here. This file will not be upgraded.</p>
56 <p><span class="GUIBUTTON">Edit</span> <span class="GUIBUTTON">Set to Cautious</span> <span class=
57 "GUIBUTTON">Set to Medium</span> <span class="GUIBUTTON">Set to Advanced</span></p>
58 <p>These have increasing levels of aggressiveness <span class="emphasis"><i class="EMPHASIS">and have no
59 influence on your browsing unless you select them explicitly in the editor</i></span>. A default installation
60 should be pre-set to <tt class="LITERAL">Cautious</tt>. New users should try this for a while before adjusting
61 the settings to more aggressive levels. The more aggressive the settings, then the more likelihood there is of
62 problems such as sites not working as they should.</p>
63 <p>The <span class="GUIBUTTON">Edit</span> button allows you to turn each action on/off individually for
64 fine-tuning. The <span class="GUIBUTTON">Cautious</span> button changes the actions list to low/safe settings
65 which will activate ad blocking and a minimal set of <span class="APPLICATION">Privoxy</span>'s features, and
66 subsequently there will be less of a chance for accidental problems. The <span class="GUIBUTTON">Medium</span>
67 button sets the list to a medium level of other features and a low level set of privacy features. The
68 <span class="GUIBUTTON">Advanced</span> button sets the list to a high level of ad blocking and medium level of
69 privacy. See the chart below. The latter three buttons over-ride any changes via with the <span class=
70 "GUIBUTTON">Edit</span> button. More fine-tuning can be done in the lower sections of this internal page.</p>
71 <p>While the actions file editor allows to enable these settings in all actions files, they are only supposed
72 to be enabled in the first one to make sure you don't unintentionally overrule earlier rules.</p>
73 <p>The default profiles, and their associated actions, as pre-defined in <tt class=
74 "FILENAME">default.action</tt> are:</p>
76 <a name="DEFAULT-CONFIGURATIONS" id="DEFAULT-CONFIGURATIONS"></a>
77 <p><b>Table 1. Default Configurations</b></p>
78 <table border="1" frame="border" rules="all" class="CALSTABLE">
79 <col width="1*" title="C1">
80 <col width="1*" title="C2">
81 <col width="1*" title="C3">
82 <col width="1*" title="C4">
93 <td>Ad-blocking Aggressiveness</td>
99 <td>Ad-filtering by size</td>
105 <td>Ad-filtering by link</td>
111 <td>Pop-up killing</td>
117 <td>Privacy Features</td>
123 <td>Cookie handling</td>
125 <td>session-only</td>
129 <td>Referer forging</td>
135 <td>GIF de-animation</td>
141 <td>Fast redirects</td>
153 <td>JavaScript taming</td>
159 <td>Web-bug killing</td>
165 <td>Image tag reordering</td>
175 <p>The list of actions files to be used are defined in the main configuration file, and are processed in the order
176 they are defined (e.g. <tt class="FILENAME">default.action</tt> is typically processed before <tt class=
177 "FILENAME">user.action</tt>). The content of these can all be viewed and edited from <a href=
178 "http://config.privoxy.org/show-status" target="_top">http://config.privoxy.org/show-status</a>. The over-riding
179 principle when applying actions, is that the last action that matches a given URL wins. The broadest, most general
180 rules go first (defined in <tt class="FILENAME">default.action</tt>), followed by any exceptions (typically also in
181 <tt class="FILENAME">default.action</tt>), which are then followed lastly by any local preferences (typically in
182 <span class="emphasis"><i class="EMPHASIS">user</i></span><tt class="FILENAME">.action</tt>). Generally, <tt class=
183 "FILENAME">user.action</tt> has the last word.</p>
184 <p>An actions file typically has multiple sections. If you want to use <span class="QUOTE">"aliases"</span> in an
185 actions file, you have to place the (optional) <a href="actions-file.html#ALIASES">alias section</a> at the top of
186 that file. Then comes the default set of rules which will apply universally to all sites and pages (be <span class=
187 "emphasis"><i class="EMPHASIS">very careful</i></span> with using such a universal set in <tt class=
188 "FILENAME">user.action</tt> or any other actions file after <tt class="FILENAME">default.action</tt>, because it
189 will override the result from consulting any previous file). And then below that, exceptions to the defined
190 universal policies. You can regard <tt class="FILENAME">user.action</tt> as an appendix to <tt class=
191 "FILENAME">default.action</tt>, with the advantage that it is a separate file, which makes preserving your personal
192 settings across <span class="APPLICATION">Privoxy</span> upgrades easier.</p>
193 <p>Actions can be used to block anything you want, including ads, banners, or just some obnoxious URL whose content
194 you would rather not see. Cookies can be accepted or rejected, or accepted only during the current browser session
195 (i.e. not written to disk), content can be modified, some JavaScripts tamed, user-tracking fooled, and much more.
196 See below for a <a href="actions-file.html#ACTIONS">complete list of actions</a>.</p>
198 <h2 class="SECT2"><a name="RIGHT-MIX" id="RIGHT-MIX">8.1. Finding the Right Mix</a></h2>
199 <p>Note that some <a href="actions-file.html#ACTIONS">actions</a>, like cookie suppression or script disabling,
200 may render some sites unusable that rely on these techniques to work properly. Finding the right mix of actions
201 is not always easy and certainly a matter of personal taste. And, things can always change, requiring refinements
202 in the configuration. In general, it can be said that the more <span class="QUOTE">"aggressive"</span> your
203 default settings (in the top section of the actions file) are, the more exceptions for <span class=
204 "QUOTE">"trusted"</span> sites you will have to make later. If, for example, you want to crunch all cookies per
205 default, you'll have to make exceptions from that rule for sites that you regularly use and that require cookies
206 for actually useful purposes, like maybe your bank, favorite shop, or newspaper.</p>
207 <p>We have tried to provide you with reasonable rules to start from in the distribution actions files. But there
208 is no general rule of thumb on these things. There just are too many variables, and sites are constantly
209 changing. Sooner or later you will want to change the rules (and read this chapter again :).</p>
212 <h2 class="SECT2"><a name="HOW-TO-EDIT" id="HOW-TO-EDIT">8.2. How to Edit</a></h2>
213 <p>The easiest way to edit the actions files is with a browser by using our browser-based editor, which can be
214 reached from <a href="http://config.privoxy.org/show-status" target=
215 "_top">http://config.privoxy.org/show-status</a>. Note: the config file option <a href=
216 "config.html#ENABLE-EDIT-ACTIONS">enable-edit-actions</a> must be enabled for this to work. The editor allows
217 both fine-grained control over every single feature on a per-URL basis, and easy choosing from wholesale sets of
218 defaults like <span class="QUOTE">"Cautious"</span>, <span class="QUOTE">"Medium"</span> or <span class=
219 "QUOTE">"Advanced"</span>. Warning: the <span class="QUOTE">"Advanced"</span> setting is more aggressive, and
220 will be more likely to cause problems for some sites. Experienced users only!</p>
221 <p>If you prefer plain text editing to GUIs, you can of course also directly edit the the actions files with your
222 favorite text editor. Look at <tt class="FILENAME">default.action</tt> which is richly commented with many good
226 <h2 class="SECT2"><a name="ACTIONS-APPLY" id="ACTIONS-APPLY">8.3. How Actions are Applied to Requests</a></h2>
227 <p>Actions files are divided into sections. There are special sections, like the <span class="QUOTE">"<a href=
228 "actions-file.html#ALIASES">alias</a>"</span> sections which will be discussed later. For now let's concentrate
229 on regular sections: They have a heading line (often split up to multiple lines for readability) which consist of
230 a list of actions, separated by whitespace and enclosed in curly braces. Below that, there is a list of URL and
231 tag patterns, each on a separate line.</p>
232 <p>To determine which actions apply to a request, the URL of the request is compared to all URL patterns in each
233 <span class="QUOTE">"action file"</span>. Every time it matches, the list of applicable actions for the request
234 is incrementally updated, using the heading of the section in which the pattern is located. The same is done
235 again for tags and tag patterns later on.</p>
236 <p>If multiple applying sections set the same action differently, the last match wins. If not, the effects are
237 aggregated. E.g. a URL might match a regular section with a heading line of <tt class="LITERAL">{ +<a href=
238 "actions-file.html#HANDLE-AS-IMAGE">handle-as-image</a> }</tt>, then later another one with just <tt class=
239 "LITERAL">{ +<a href="actions-file.html#BLOCK">block</a> }</tt>, resulting in <span class="emphasis"><i class=
240 "EMPHASIS">both</i></span> actions to apply. And there may well be cases where you will want to combine actions
241 together. Such a section then might look like:</p>
242 <table border="0" bgcolor="#E0E0E0" width="100%">
245 <pre class="SCREEN"> { +<tt class="LITERAL">handle-as-image</tt> +<tt class=
246 "LITERAL">block{Banner ads.}</tt> }
247 # Block these as if they were images. Send no block page.
249 media.example.com/.*banners
250 .example.com/images/ads/</pre>
254 <p>You can trace this process for URL patterns and any given URL by visiting <a href=
255 "http://config.privoxy.org/show-url-info" target="_top">http://config.privoxy.org/show-url-info</a>.</p>
256 <p>Examples and more detail on this is provided in the Appendix, <a href=
257 "appendix.html#ACTIONSANAT">Troubleshooting: Anatomy of an Action</a> section.</p>
260 <h2 class="SECT2"><a name="AF-PATTERNS" id="AF-PATTERNS">8.4. Patterns</a></h2>
261 <p>As mentioned, <span class="APPLICATION">Privoxy</span> uses <span class="QUOTE">"patterns"</span> to determine
262 what <span class="emphasis"><i class="EMPHASIS">actions</i></span> might apply to which sites and pages your
263 browser attempts to access. These <span class="QUOTE">"patterns"</span> use wild card type <span class=
264 "emphasis"><i class="EMPHASIS">pattern</i></span> matching to achieve a high degree of flexibility. This allows
265 one expression to be expanded and potentially match against many similar patterns.</p>
266 <p>Generally, an URL pattern has the form <tt class="LITERAL"><host><port>/<path></tt>, where
267 the <tt class="LITERAL"><host></tt>, the <tt class="LITERAL"><port></tt> and the <tt class=
268 "LITERAL"><path></tt> are optional. (This is why the special <tt class="LITERAL">/</tt> pattern matches all
269 URLs). Note that the protocol portion of the URL pattern (e.g. <tt class="LITERAL">http://</tt>) should
270 <span class="emphasis"><i class="EMPHASIS">not</i></span> be included in the pattern. This is assumed
272 <p>The pattern matching syntax is different for the host and path parts of the URL. The host part uses a simple
273 globbing type matching technique, while the path part uses more flexible <a href=
274 "https://en.wikipedia.org/wiki/Regular_expressions" target="_top"><span class="QUOTE">"Regular
275 Expressions"</span></a> (POSIX 1003.2).</p>
276 <p>The port part of a pattern is a decimal port number preceded by a colon (<tt class="LITERAL">:</tt>). If the
277 host part contains a numerical IPv6 address, it has to be put into angle brackets (<tt class="LITERAL"><</tt>,
278 <tt class="LITERAL">></tt>).</p>
279 <div class="VARIABLELIST">
281 <dt><tt class="LITERAL">www.example.com/</tt></dt>
283 <p>is a host-only pattern and will match any request to <tt class="LITERAL">www.example.com</tt>,
284 regardless of which document on that server is requested. So ALL pages in this domain would be covered by
285 the scope of this action. Note that a simple <tt class="LITERAL">example.com</tt> is different and would
288 <dt><tt class="LITERAL">www.example.com</tt></dt>
290 <p>means exactly the same. For host-only patterns, the trailing <tt class="LITERAL">/</tt> may be
293 <dt><tt class="LITERAL">www.example.com/index.html</tt></dt>
295 <p>matches all the documents on <tt class="LITERAL">www.example.com</tt> whose name starts with <tt class=
296 "LITERAL">/index.html</tt>.</p>
298 <dt><tt class="LITERAL">www.example.com/index.html$</tt></dt>
300 <p>matches only the single document <tt class="LITERAL">/index.html</tt> on <tt class=
301 "LITERAL">www.example.com</tt>.</p>
303 <dt><tt class="LITERAL">/index.html$</tt></dt>
305 <p>matches the document <tt class="LITERAL">/index.html</tt>, regardless of the domain, i.e. on
306 <span class="emphasis"><i class="EMPHASIS">any</i></span> web server anywhere.</p>
308 <dt><tt class="LITERAL">/</tt></dt>
310 <p>Matches any URL because there's no requirement for either the domain or the path to match anything.</p>
312 <dt><tt class="LITERAL">:8000/</tt></dt>
314 <p>Matches any URL pointing to TCP port 8000.</p>
316 <dt><tt class="LITERAL">10.0.0.1/</tt></dt>
318 <p>Matches any URL with the host address <tt class="LITERAL">10.0.0.1</tt>. (Note that the real URL uses
319 plain brackets, not angle brackets.)</p>
321 <dt><tt class="LITERAL"><2001:db8::1>/</tt></dt>
323 <p>Matches any URL with the host address <tt class="LITERAL">2001:db8::1</tt>. (Note that the real URL uses
324 plain brackets, not angle brackets.)</p>
326 <dt><tt class="LITERAL">index.html</tt></dt>
328 <p>matches nothing, since it would be interpreted as a domain name and there is no top-level domain called
329 <tt class="LITERAL">.html</tt>. So its a mistake.</p>
334 <h3 class="SECT3"><a name="HOST-PATTERN" id="HOST-PATTERN">8.4.1. The Host Pattern</a></h3>
335 <p>The matching of the host part offers some flexible options: if the host pattern starts or ends with a dot,
336 it becomes unanchored at that end. The host pattern is often referred to as domain pattern as it is usually
337 used to match domain names and not IP addresses. For example:</p>
338 <div class="VARIABLELIST">
340 <dt><tt class="LITERAL">.example.com</tt></dt>
342 <p>matches any domain with first-level domain <tt class="LITERAL">com</tt> and second-level domain
343 <tt class="LITERAL">example</tt>. For example <tt class="LITERAL">www.example.com</tt>, <tt class=
344 "LITERAL">example.com</tt> and <tt class="LITERAL">foo.bar.baz.example.com</tt>. Note that it wouldn't
345 match if the second-level domain was <tt class="LITERAL">another-example</tt>.</p>
347 <dt><tt class="LITERAL">www.</tt></dt>
349 <p>matches any domain that <span class="emphasis"><i class="EMPHASIS">STARTS</i></span> with <tt class=
350 "LITERAL">www.</tt> (It also matches the domain <tt class="LITERAL">www</tt> but most of the time that
353 <dt><tt class="LITERAL">.example.</tt></dt>
355 <p>matches any domain that <span class="emphasis"><i class="EMPHASIS">CONTAINS</i></span> <tt class=
356 "LITERAL">.example.</tt>. And, by the way, also included would be any files or documents that exist
357 within that domain since no path limitations are specified. (Correctly speaking: It matches any FQDN that
358 contains <tt class="LITERAL">example</tt> as a domain.) This might be <tt class=
359 "LITERAL">www.example.com</tt>, <tt class="LITERAL">news.example.de</tt>, or <tt class=
360 "LITERAL">www.example.net/cgi/testing.pl</tt> for instance. All these cases are matched.</p>
364 <p>Additionally, there are wild-cards that you can use in the domain names themselves. These work similarly to
365 shell globbing type wild-cards: <span class="QUOTE">"*"</span> represents zero or more arbitrary characters
366 (this is equivalent to the <a href="https://en.wikipedia.org/wiki/Regular_expressions" target=
367 "_top"><span class="QUOTE">"Regular Expression"</span></a> based syntax of <span class="QUOTE">".*"</span>),
368 <span class="QUOTE">"?"</span> represents any single character (this is equivalent to the regular expression
369 syntax of a simple <span class="QUOTE">"."</span>), and you can define <span class="QUOTE">"character
370 classes"</span> in square brackets which is similar to the same regular expression technique. All of this can
372 <div class="VARIABLELIST">
374 <dt><tt class="LITERAL">ad*.example.com</tt></dt>
376 <p>matches <span class="QUOTE">"adserver.example.com"</span>, <span class=
377 "QUOTE">"ads.example.com"</span>, etc but not <span class="QUOTE">"sfads.example.com"</span></p>
379 <dt><tt class="LITERAL">*ad*.example.com</tt></dt>
381 <p>matches all of the above, and then some.</p>
383 <dt><tt class="LITERAL">.?pix.com</tt></dt>
385 <p>matches <tt class="LITERAL">www.ipix.com</tt>, <tt class="LITERAL">pictures.epix.com</tt>, <tt class=
386 "LITERAL">a.b.c.d.e.upix.com</tt> etc.</p>
388 <dt><tt class="LITERAL">www[1-9a-ez].example.c*</tt></dt>
390 <p>matches <tt class="LITERAL">www1.example.com</tt>, <tt class="LITERAL">www4.example.cc</tt>,
391 <tt class="LITERAL">wwwd.example.cy</tt>, <tt class="LITERAL">wwwz.example.com</tt> etc., but
392 <span class="emphasis"><i class="EMPHASIS">not</i></span> <tt class="LITERAL">wwww.example.com</tt>.</p>
396 <p>While flexible, this is not the sophistication of full regular expression based syntax.</p>
397 <p>When compiled with FEATURE_PCRE_HOST_PATTERNS patterns can be prefixed with <span class=
398 "QUOTE">"PCRE-HOST-PATTERN:"</span> in which case full regular expression (PCRE) can be used for the host
402 <h3 class="SECT3"><a name="PATH-PATTERN" id="PATH-PATTERN">8.4.2. The Path Pattern</a></h3>
403 <p><span class="APPLICATION">Privoxy</span> uses <span class="QUOTE">"modern"</span> POSIX 1003.2 <a href=
404 "https://en.wikipedia.org/wiki/Regular_expressions" target="_top"><span class="QUOTE">"Regular
405 Expressions"</span></a> for matching the path portion (after the slash), and is thus more flexible.</p>
406 <p>There is an <a href="appendix.html#REGEX">Appendix</a> with a brief quick-start into regular expressions,
407 you also might want to have a look at your operating system's documentation on regular expressions (try
408 <tt class="LITERAL">man re_format</tt>).</p>
409 <p>Note that the path pattern is automatically left-anchored at the <span class="QUOTE">"/"</span>, i.e. it
410 matches as if it would start with a <span class="QUOTE">"^"</span> (regular expression speak for the beginning
412 <p>Please also note that matching in the path is <span class="emphasis"><i class="EMPHASIS">CASE
413 INSENSITIVE</i></span> by default, but you can switch to case sensitive at any point in the pattern by using
414 the <span class="QUOTE">"(?-i)"</span> switch: <tt class="LITERAL">www.example.com/(?-i)PaTtErN.*</tt> will
415 match only documents whose path starts with <tt class="LITERAL">PaTtErN</tt> in <span class=
416 "emphasis"><i class="EMPHASIS">exactly</i></span> this capitalization.</p>
417 <div class="VARIABLELIST">
419 <dt><tt class="LITERAL">.example.com/.*</tt></dt>
421 <p>Is equivalent to just <span class="QUOTE">".example.com"</span>, since any documents within that
422 domain are matched with or without the <span class="QUOTE">".*"</span> regular expression. This is
425 <dt><tt class="LITERAL">.example.com/.*/index.html$</tt></dt>
427 <p>Will match any page in the domain of <span class="QUOTE">"example.com"</span> that is named
428 <span class="QUOTE">"index.html"</span>, and that is part of some path. For example, it matches
429 <span class="QUOTE">"www.example.com/testing/index.html"</span> but NOT <span class=
430 "QUOTE">"www.example.com/index.html"</span> because the regular expression called for at least two
431 <span class="QUOTE">"/'s"</span>, thus the path requirement. It also would match <span class=
432 "QUOTE">"www.example.com/testing/index_html"</span>, because of the special meta-character <span class=
433 "QUOTE">"."</span>.</p>
435 <dt><tt class="LITERAL">.example.com/(.*/)?index\.html$</tt></dt>
437 <p>This regular expression is conditional so it will match any page named <span class=
438 "QUOTE">"index.html"</span> regardless of path which in this case can have one or more <span class=
439 "QUOTE">"/'s"</span>. And this one must contain exactly <span class="QUOTE">".html"</span> (and end with
442 <dt><tt class="LITERAL">.example.com/(.*/)(ads|banners?|junk)</tt></dt>
444 <p>This regular expression will match any path of <span class="QUOTE">"example.com"</span> that contains
445 any of the words <span class="QUOTE">"ads"</span>, <span class="QUOTE">"banner"</span>, <span class=
446 "QUOTE">"banners"</span> (because of the <span class="QUOTE">"?"</span>) or <span class=
447 "QUOTE">"junk"</span>. The path does not have to end in these words, just contain them. The path has to
448 contain at least two slashes (including the one at the beginning).</p>
450 <dt><tt class="LITERAL">.example.com/(.*/)(ads|banners?|junk)/.*\.(jpe?g|gif|png)$</tt></dt>
452 <p>This is very much the same as above, except now it must end in either <span class=
453 "QUOTE">".jpg"</span>, <span class="QUOTE">".jpeg"</span>, <span class="QUOTE">".gif"</span> or
454 <span class="QUOTE">".png"</span>. So this one is limited to common image formats.</p>
458 <p>There are many, many good examples to be found in <tt class="FILENAME">default.action</tt>, and more
459 tutorials below in <a href="appendix.html#REGEX">Appendix on regular expressions</a>.</p>
462 <h3 class="SECT3"><a name="TAG-PATTERN" id="TAG-PATTERN">8.4.3. The Request Tag Pattern</a></h3>
463 <p>Request tag patterns are used to change the applying actions based on the request's tags. Tags can be
464 created based on HTTP headers with either the <a href=
465 "actions-file.html#CLIENT-HEADER-TAGGER">client-header-tagger</a> or the <a href=
466 "actions-file.html#SERVER-HEADER-TAGGER">server-header-tagger</a> action.</p>
467 <p>Request tag patterns have to start with <span class="QUOTE">"TAG:"</span>, so <span class=
468 "APPLICATION">Privoxy</span> can tell them apart from other patterns. Everything after the colon including
469 white space, is interpreted as a regular expression with path pattern syntax, except that tag patterns aren't
470 left-anchored automatically (<span class="APPLICATION">Privoxy</span> doesn't silently add a <span class=
471 "QUOTE">"^"</span>, you have to do it yourself if you need it).</p>
472 <p>To match all requests that are tagged with <span class="QUOTE">"foo"</span> your pattern line should be
473 <span class="QUOTE">"TAG:^foo$"</span>, <span class="QUOTE">"TAG:foo"</span> would work as well, but it would
474 also match requests whose tags contain <span class="QUOTE">"foo"</span> somewhere. <span class="QUOTE">"TAG:
475 foo"</span> wouldn't work as it requires white space.</p>
476 <p>Sections can contain URL and request tag patterns at the same time, but request tag patterns are checked
477 after the URL patterns and thus always overrule them, even if they are located before the URL patterns.</p>
478 <p>Once a new request tag is added, Privoxy checks right away if it's matched by one of the request tag
479 patterns and updates the action settings accordingly. As a result request tags can be used to activate other
480 tagger actions, as long as these other taggers look for headers that haven't already be parsed.</p>
481 <p>For example you could tag client requests which use the <tt class="LITERAL">POST</tt> method, then use this
482 tag to activate another tagger that adds a tag if cookies are sent, and then use a block action based on the
483 cookie tag. This allows the outcome of one action, to be input into a subsequent action. However if you'd
484 reverse the position of the described taggers, and activated the method tagger based on the cookie tagger, no
485 method tags would be created. The method tagger would look for the request line, but at the time the cookie tag
486 is created, the request line has already been parsed.</p>
487 <p>While this is a limitation you should be aware of, this kind of indirection is seldom needed anyway and even
488 the example doesn't make too much sense.</p>
491 <h3 class="SECT3"><a name="NEGATIVE-TAG-PATTERNS" id="NEGATIVE-TAG-PATTERNS">8.4.4. The Negative Request Tag
493 <p>To match requests that do not have a certain request tag, specify a negative tag pattern by prefixing the
494 tag pattern line with either <span class="QUOTE">"NO-REQUEST-TAG:"</span> or <span class=
495 "QUOTE">"NO-RESPONSE-TAG:"</span> instead of <span class="QUOTE">"TAG:"</span>.</p>
496 <p>Negative request tag patterns created with <span class="QUOTE">"NO-REQUEST-TAG:"</span> are checked after
497 all client headers are scanned, the ones created with <span class="QUOTE">"NO-RESPONSE-TAG:"</span> are checked
498 after all server headers are scanned. In both cases all the created tags are considered.</p>
501 <h3 class="SECT3"><a name="CLIENT-TAG-PATTERN" id="CLIENT-TAG-PATTERN">8.4.5. The Client Tag Pattern</a></h3>
502 <div class="WARNING">
503 <table class="WARNING" border="1" width="100%">
505 <td align="center"><b>Warning</b></td>
509 <p>This is an experimental feature. The syntax is likely to change in future versions.</p>
514 <p>Client tag patterns are not set based on HTTP headers but based on the client's IP address. Users can enable
515 them themselves, but the Privoxy admin controls which tags are available and what their effect is.</p>
516 <p>After a client-specific tag has been defined with the <a href=
517 "config.html#CLIENT-SPECIFIC-TAG">client-specific-tag</a>, directive, action sections can be activated based on
518 the tag by using a CLIENT-TAG pattern. The CLIENT-TAG pattern is evaluated at the same priority as URL
519 patterns, as a result the last matching pattern wins. Tags that are created based on client or server headers
520 are evaluated later on and can overrule CLIENT-TAG and URL patterns!</p>
521 <p>The tag is set for all requests that come from clients that requested it to be set. Note that "clients" are
522 differentiated by IP address, if the IP address changes the tag has to be requested again.</p>
523 <p>Clients can request tags to be set by using the CGI interface <a href=
524 "http://config.privoxy.org/client-tags" target="_top">http://config.privoxy.org/client-tags</a>.</p>
526 <table border="0" bgcolor="#E0E0E0" width="100%">
529 <pre class="SCREEN"># If the admin defined the client-specific-tag circumvent-blocks,
530 # and the request comes from a client that previously requested
531 # the tag to be set, overrule all previous +block actions that
532 # are enabled based on URL to CLIENT-TAG patterns.
534 CLIENT-TAG:^circumvent-blocks$
536 # This section is not overruled because it's located after
538 {+block{Nobody is supposed to request this.}}
539 example.org/blocked-example-page</pre>
546 <h2 class="SECT2"><a name="ACTIONS" id="ACTIONS">8.5. Actions</a></h2>
547 <p>All actions are disabled by default, until they are explicitly enabled somewhere in an actions file. Actions
548 are turned on if preceded with a <span class="QUOTE">"+"</span>, and turned off if preceded with a <span class=
549 "QUOTE">"-"</span>. So a <tt class="LITERAL">+action</tt> means <span class="QUOTE">"do that action"</span>, e.g.
550 <tt class="LITERAL">+block</tt> means <span class="QUOTE">"please block URLs that match the following
551 patterns"</span>, and <tt class="LITERAL">-block</tt> means <span class="QUOTE">"don't block URLs that match the
552 following patterns, even if <tt class="LITERAL">+block</tt> previously applied."</span></p>
553 <p>Again, actions are invoked by placing them on a line, enclosed in curly braces and separated by whitespace,
554 like in <tt class="LITERAL">{+some-action -some-other-action{some-parameter}}</tt>, followed by a list of URL
555 patterns, one per line, to which they apply. Together, the actions line and the following pattern lines make up a
556 section of the actions file.</p>
557 <p>Actions fall into three categories:</p>
560 <p>Boolean, i.e the action can only be <span class="QUOTE">"enabled"</span> or <span class=
561 "QUOTE">"disabled"</span>. Syntax:</p>
562 <table border="0" bgcolor="#E0E0E0" width="90%">
565 <pre class="SCREEN"> +<tt class="REPLACEABLE"><i>name</i></tt> # enable action <tt class=
566 "REPLACEABLE"><i>name</i></tt>
567 -<tt class="REPLACEABLE"><i>name</i></tt> # disable action <tt class="REPLACEABLE"><i>name</i></tt></pre>
571 <p>Example: <tt class="LITERAL">+handle-as-image</tt></p>
574 <p>Parameterized, where some value is required in order to enable this type of action. Syntax:</p>
575 <table border="0" bgcolor="#E0E0E0" width="90%">
578 <pre class="SCREEN"> +<tt class="REPLACEABLE"><i>name</i></tt>{<tt class=
579 "REPLACEABLE"><i>param</i></tt>} # enable action and set parameter to <tt class=
580 "REPLACEABLE"><i>param</i></tt>,
581 # overwriting parameter from previous match if necessary
582 -<tt class="REPLACEABLE"><i>name</i></tt> # disable action. The parameter can be omitted</pre>
586 <p>Note that if the URL matches multiple positive forms of a parameterized action, the last match wins, i.e.
587 the params from earlier matches are simply ignored.</p>
588 <p>Example: <tt class="LITERAL">+hide-user-agent{Mozilla/5.0 (X11; U; FreeBSD i386; en-US; rv:1.8.1.4)
589 Gecko/20070602 Firefox/2.0.0.4}</tt></p>
592 <p>Multi-value. These look exactly like parameterized actions, but they behave differently: If the action
593 applies multiple times to the same URL, but with different parameters, <span class="emphasis"><i class=
594 "EMPHASIS">all</i></span> the parameters from <span class="emphasis"><i class="EMPHASIS">all</i></span>
595 matches are remembered. This is used for actions that can be executed for the same request repeatedly, like
596 adding multiple headers, or filtering through multiple filters. Syntax:</p>
597 <table border="0" bgcolor="#E0E0E0" width="90%">
600 <pre class="SCREEN"> +<tt class="REPLACEABLE"><i>name</i></tt>{<tt class=
601 "REPLACEABLE"><i>param</i></tt>} # enable action and add <tt class=
602 "REPLACEABLE"><i>param</i></tt> to the list of parameters
603 -<tt class="REPLACEABLE"><i>name</i></tt>{<tt class=
604 "REPLACEABLE"><i>param</i></tt>} # remove the parameter <tt class=
605 "REPLACEABLE"><i>param</i></tt> from the list of parameters
606 # If it was the last one left, disable the action.
608 "REPLACEABLE"><i>-name</i></tt> # disable this action completely and remove all parameters from the list</pre>
612 <p>Examples: <tt class="LITERAL">+add-header{X-Fun-Header: Some text}</tt> and <tt class=
613 "LITERAL">+filter{html-annoyances}</tt></p>
616 <p>If nothing is specified in any actions file, no <span class="QUOTE">"actions"</span> are taken. So in this
617 case <span class="APPLICATION">Privoxy</span> would just be a normal, non-blocking, non-filtering proxy. You must
618 specifically enable the privacy and blocking features you need (although the provided default actions files will
619 give a good starting point).</p>
620 <p>Later defined action sections always over-ride earlier ones of the same type. So exceptions to any rules you
621 make, should come in the latter part of the file (or in a file that is processed later when using multiple
622 actions files such as <tt class="FILENAME">user.action</tt>). For multi-valued actions, the actions are applied
623 in the order they are specified. Actions files are processed in the order they are defined in <tt class=
624 "FILENAME">config</tt> (the default installation has three actions files). It also quite possible for any given
625 URL to match more than one <span class="QUOTE">"pattern"</span> (because of wildcards and regular expressions),
626 and thus to trigger more than one set of actions! Last match wins.</p>
627 <p>The list of valid <span class="APPLICATION">Privoxy</span> actions are:</p>
629 <h4 class="SECT3"><a name="ADD-HEADER" id="ADD-HEADER">8.5.1. add-header</a></h4>
630 <div class="VARIABLELIST">
632 <dt>Typical use:</dt>
634 <p>Confuse log analysis, custom applications</p>
638 <p>Sends a user defined HTTP header to the web server.</p>
646 <p>Any string value is possible. Validity of the defined HTTP headers is not checked. It is recommended
647 that you use the <span class="QUOTE">"<tt class="LITERAL">X-</tt>"</span> prefix for custom headers.</p>
651 <p>This action may be specified multiple times, in order to define multiple headers. This is rarely
652 needed for the typical user. If you don't know what <span class="QUOTE">"HTTP headers"</span> are, you
653 definitely don't need to worry about this one.</p>
654 <p>Headers added by this action are not modified by other actions.</p>
656 <dt>Example usage:</dt>
658 <table border="0" bgcolor="#E0E0E0" width="90%">
661 <pre class="SCREEN"># Add a DNT ("Do not track") header to all requests,
662 # event to those that already have one.
664 # This is just an example, not a recommendation.
666 # There is no reason to believe that user-tracking websites care
667 # about the DNT header and depending on the User-Agent, adding the
668 # header may make user-tracking easier.
669 {+add-header{DNT: 1}}
679 <h4 class="SECT3"><a name="BLOCK" id="BLOCK">8.5.2. block</a></h4>
680 <div class="VARIABLELIST">
682 <dt>Typical use:</dt>
684 <p>Block ads or other unwanted content</p>
688 <p>Requests for URLs to which this action applies are blocked, i.e. the requests are trapped by
689 <span class="APPLICATION">Privoxy</span> and the requested URL is never retrieved, but is answered
690 locally with a substitute page or image, as determined by the <tt class="LITERAL"><a href=
691 "actions-file.html#HANDLE-AS-IMAGE">handle-as-image</a></tt>, <tt class="LITERAL"><a href=
692 "actions-file.html#SET-IMAGE-BLOCKER">set-image-blocker</a></tt>, and <tt class="LITERAL"><a href=
693 "actions-file.html#HANDLE-AS-EMPTY-DOCUMENT">handle-as-empty-document</a></tt> actions.</p>
697 <p>Parameterized.</p>
701 <p>A block reason that should be given to the user.</p>
705 <p><span class="APPLICATION">Privoxy</span> sends a special <span class="QUOTE">"BLOCKED"</span> page for
706 requests to blocked pages. This page contains the block reason given as parameter, a link to find out why
707 the block action applies, and a click-through to the blocked content (the latter only if the force
708 feature is available and enabled).</p>
709 <p>A very important exception occurs if <span class="emphasis"><i class="EMPHASIS">both</i></span>
710 <tt class="LITERAL">block</tt> and <tt class="LITERAL"><a href=
711 "actions-file.html#HANDLE-AS-IMAGE">handle-as-image</a></tt>, apply to the same request: it will then be
712 replaced by an image. If <tt class="LITERAL"><a href=
713 "actions-file.html#SET-IMAGE-BLOCKER">set-image-blocker</a></tt> (see below) also applies, the type of
714 image will be determined by its parameter, if not, the standard checkerboard pattern is sent.</p>
715 <p>It is important to understand this process, in order to understand how <span class=
716 "APPLICATION">Privoxy</span> deals with ads and other unwanted content. Blocking is a core feature, and
717 one upon which various other features depend.</p>
718 <p>The <tt class="LITERAL"><a href="actions-file.html#FILTER">filter</a></tt> action can perform a very
719 similar task, by <span class="QUOTE">"blocking"</span> banner images and other content through rewriting
720 the relevant URLs in the document's HTML source, so they don't get requested in the first place. Note
721 that this is a totally different technique, and it's easy to confuse the two.</p>
723 <dt>Example usage (section):</dt>
725 <table border="0" bgcolor="#E0E0E0" width="90%">
728 <pre class="SCREEN">{+block{No nasty stuff for you.}}
729 # Block and replace with "blocked" page
730 .nasty-stuff.example.com
732 {+block{Doubleclick banners.} +handle-as-image}
733 # Block and replace with image
737 {+block{Layered ads.} +handle-as-empty-document}
738 # Block and then ignore
739 adserver.example.net/.*\.js$</pre>
748 <h4 class="SECT3"><a name="CHANGE-X-FORWARDED-FOR" id="CHANGE-X-FORWARDED-FOR">8.5.3.
749 change-x-forwarded-for</a></h4>
750 <div class="VARIABLELIST">
752 <dt>Typical use:</dt>
754 <p>Improve privacy by not forwarding the source of the request in the HTTP headers.</p>
758 <p>Deletes the <span class="QUOTE">"X-Forwarded-For:"</span> HTTP header from the client request, or adds
763 <p>Parameterized.</p>
769 <p><span class="QUOTE">"block"</span> to delete the header.</p>
772 <p><span class="QUOTE">"add"</span> to create the header (or append the client's IP address to an
773 already existing one).</p>
779 <p>It is safe and recommended to use <tt class="LITERAL">block</tt>.</p>
780 <p>Forwarding the source address of the request may make sense in some multi-user setups but is also a
783 <dt>Example usage:</dt>
785 <table border="0" bgcolor="#E0E0E0" width="90%">
788 <pre class="SCREEN">+change-x-forwarded-for{block}</pre>
797 <h4 class="SECT3"><a name="CLIENT-HEADER-FILTER" id="CLIENT-HEADER-FILTER">8.5.4. client-header-filter</a></h4>
798 <div class="VARIABLELIST">
800 <dt>Typical use:</dt>
802 <p>Rewrite or remove single client headers.</p>
806 <p>All client headers to which this action applies are filtered on-the-fly through the specified regular
807 expression based substitutions.</p>
815 <p>The name of a client-header filter, as defined in one of the <a href="filter-file.html">filter
820 <p>Client-header filters are applied to each header on its own, not to all at once. This makes it easier
821 to diagnose problems, but on the downside you can't write filters that only change header x if header y's
822 value is z. You can do that by using tags though.</p>
823 <p>Client-header filters are executed after the other header actions have finished and use their output
825 <p>If the request URI gets changed, <span class="APPLICATION">Privoxy</span> will detect that and use the
826 new one. This can be used to rewrite the request destination behind the client's back, for example to
827 specify a Tor exit relay for certain requests.</p>
828 <p>Please refer to the <a href="filter-file.html">filter file chapter</a> to learn which client-header
829 filters are available by default, and how to create your own.</p>
831 <dt>Example usage (section):</dt>
833 <table border="0" bgcolor="#E0E0E0" width="90%">
836 <pre class="SCREEN"># Hide Tor exit notation in Host and Referer Headers
837 {+client-header-filter{hide-tor-exit-notation}}
847 <h4 class="SECT3"><a name="CLIENT-HEADER-TAGGER" id="CLIENT-HEADER-TAGGER">8.5.5. client-header-tagger</a></h4>
848 <div class="VARIABLELIST">
850 <dt>Typical use:</dt>
852 <p>Block requests based on their headers.</p>
856 <p>Client headers to which this action applies are filtered on-the-fly through the specified regular
857 expression based substitutions, the result is used as tag.</p>
865 <p>The name of a client-header tagger, as defined in one of the <a href="filter-file.html">filter
870 <p>Client-header taggers are applied to each header on its own, and as the header isn't modified, each
871 tagger <span class="QUOTE">"sees"</span> the original.</p>
872 <p>Client-header taggers are the first actions that are executed and their tags can be used to control
873 every other action.</p>
875 <dt>Example usage (section):</dt>
877 <table border="0" bgcolor="#E0E0E0" width="90%">
880 <pre class="SCREEN"># Tag every request with the User-Agent header
881 {+client-header-tagger{user-agent}}
884 # Tagging itself doesn't change the action
885 # settings, sections with TAG patterns do:
887 # If it's a download agent, use a different forwarding proxy,
888 # show the real User-Agent and make sure resume works.
889 {+forward-override{forward-socks5 10.0.0.2:2222 .} \
890 -hide-if-modified-since \
891 -overwrite-last-modified \
896 TAG:^User-Agent: NetBSD-ftp/
897 TAG:^User-Agent: Novell ZYPP Installer
898 TAG:^User-Agent: RPM APT-HTTP/
899 TAG:^User-Agent: fetch libfetch/
900 TAG:^User-Agent: Ubuntu APT-HTTP/
901 TAG:^User-Agent: MPlayer/</pre>
905 <table border="0" bgcolor="#E0E0E0" width="90%">
908 <pre class="SCREEN"># Tag all requests with the Range header set
909 {+client-header-tagger{range-requests}}
912 # Disable filtering for the tagged requests.
914 # With filtering enabled Privoxy would remove the Range headers
915 # to be able to filter the whole response. The downside is that
916 # it prevents clients from resuming downloads or skipping over
917 # parts of multimedia files.
918 {-filter -deanimate-gifs}
919 TAG:^RANGE-REQUEST$</pre>
923 <table border="0" bgcolor="#E0E0E0" width="90%">
926 <pre class="SCREEN"># Tag all requests with the client IP address
928 # (Technically the client IP address isn't included in the
929 # client headers but client-header taggers can set it anyway.
930 # For details see the tagger in default.filter)
931 {+client-header-tagger{client-ip-address}}
934 # Change forwarding settings for requests coming from address 10.0.0.1
935 {+forward-override{forward-socks5 127.0.1.2:2222 .}}
936 TAG:^IP-ADDRESS: 10\.0\.0\.1$</pre>
945 <h4 class="SECT3"><a name="CONTENT-TYPE-OVERWRITE" id="CONTENT-TYPE-OVERWRITE">8.5.6.
946 content-type-overwrite</a></h4>
947 <div class="VARIABLELIST">
949 <dt>Typical use:</dt>
951 <p>Stop useless download menus from popping up, or change the browser's rendering mode</p>
955 <p>Replaces the <span class="QUOTE">"Content-Type:"</span> HTTP server header.</p>
959 <p>Parameterized.</p>
967 <p>The <span class="QUOTE">"Content-Type:"</span> HTTP server header is used by the browser to decide
968 what to do with the document. The value of this header can cause the browser to open a download menu
969 instead of displaying the document by itself, even if the document's format is supported by the
971 <p>The declared content type can also affect which rendering mode the browser chooses. If XHTML is
972 delivered as <span class="QUOTE">"text/html"</span>, many browsers treat it as yet another broken HTML
973 document. If it is send as <span class="QUOTE">"application/xml"</span>, browsers with XHTML support will
974 only display it, if the syntax is correct.</p>
975 <p>If you see a web site that proudly uses XHTML buttons, but sets <span class="QUOTE">"Content-Type:
976 text/html"</span>, you can use <span class="APPLICATION">Privoxy</span> to overwrite it with <span class=
977 "QUOTE">"application/xml"</span> and validate the web master's claim inside your XHTML-supporting
978 browser. If the syntax is incorrect, the browser will complain loudly.</p>
979 <p>You can also go the opposite direction: if your browser prints error messages instead of rendering a
980 document falsely declared as XHTML, you can overwrite the content type with <span class=
981 "QUOTE">"text/html"</span> and have it rendered as broken HTML document.</p>
982 <p>By default <tt class="LITERAL">content-type-overwrite</tt> only replaces <span class=
983 "QUOTE">"Content-Type:"</span> headers that look like some kind of text. If you want to overwrite it
984 unconditionally, you have to combine it with <tt class="LITERAL"><a href=
985 "actions-file.html#FORCE-TEXT-MODE">force-text-mode</a></tt>. This limitation exists for a reason, think
986 twice before circumventing it.</p>
987 <p>Most of the time it's easier to replace this action with a custom <tt class="LITERAL"><a href=
988 "actions-file.html#SERVER-HEADER-FILTER">server-header filter</a></tt>. It allows you to activate it for
989 every document of a certain site and it will still only replace the content types you aimed at.</p>
990 <p>Of course you can apply <tt class="LITERAL">content-type-overwrite</tt> to a whole site and then make
991 URL based exceptions, but it's a lot more work to get the same precision.</p>
993 <dt>Example usage (sections):</dt>
995 <table border="0" bgcolor="#E0E0E0" width="90%">
998 <pre class="SCREEN"># Check if www.example.net/ really uses valid XHTML
999 { +content-type-overwrite{application/xml} }
1002 # but leave the content type unmodified if the URL looks like a style sheet
1003 {-content-type-overwrite}
1004 www.example.net/.*\.css$
1005 www.example.net/.*style</pre>
1014 <h4 class="SECT3"><a name="CRUNCH-CLIENT-HEADER" id="CRUNCH-CLIENT-HEADER">8.5.7. crunch-client-header</a></h4>
1015 <div class="VARIABLELIST">
1017 <dt>Typical use:</dt>
1019 <p>Remove a client header <span class="APPLICATION">Privoxy</span> has no dedicated action for.</p>
1023 <p>Deletes every header sent by the client that contains the string the user supplied as parameter.</p>
1027 <p>Parameterized.</p>
1035 <p>This action allows you to block client headers for which no dedicated <span class=
1036 "APPLICATION">Privoxy</span> action exists. <span class="APPLICATION">Privoxy</span> will remove every
1037 client header that contains the string you supplied as parameter.</p>
1038 <p>Regular expressions are <span class="emphasis"><i class="EMPHASIS">not supported</i></span> and you
1039 can't use this action to block different headers in the same request, unless they contain the same
1041 <p><tt class="LITERAL">crunch-client-header</tt> is only meant for quick tests. If you have to block
1042 several different headers, or only want to modify parts of them, you should use a <tt class=
1043 "LITERAL"><a href="actions-file.html#CLIENT-HEADER-FILTER">client-header filter</a></tt>.</p>
1044 <div class="WARNING">
1045 <table class="WARNING" border="1" width="90%">
1047 <td align="center"><b>Warning</b></td>
1051 <p>Don't block any header without understanding the consequences.</p>
1057 <dt>Example usage (section):</dt>
1059 <table border="0" bgcolor="#E0E0E0" width="90%">
1062 <pre class="SCREEN"># Block the non-existent "Privacy-Violation:" client header
1063 { +crunch-client-header{Privacy-Violation:} }
1073 <h4 class="SECT3"><a name="CRUNCH-IF-NONE-MATCH" id="CRUNCH-IF-NONE-MATCH">8.5.8. crunch-if-none-match</a></h4>
1074 <div class="VARIABLELIST">
1076 <dt>Typical use:</dt>
1078 <p>Prevent yet another way to track the user's steps between sessions.</p>
1082 <p>Deletes the <span class="QUOTE">"If-None-Match:"</span> HTTP client header.</p>
1094 <p>Removing the <span class="QUOTE">"If-None-Match:"</span> HTTP client header is useful for filter
1095 testing, where you want to force a real reload instead of getting status code <span class=
1096 "QUOTE">"304"</span> which would cause the browser to use a cached copy of the page.</p>
1097 <p>It is also useful to make sure the header isn't used as a cookie replacement (unlikely but
1099 <p>Blocking the <span class="QUOTE">"If-None-Match:"</span> header shouldn't cause any caching problems,
1100 as long as the <span class="QUOTE">"If-Modified-Since:"</span> header isn't blocked or missing as
1102 <p>It is recommended to use this action together with <tt class="LITERAL"><a href=
1103 "actions-file.html#HIDE-IF-MODIFIED-SINCE">hide-if-modified-since</a></tt> and <tt class=
1104 "LITERAL"><a href="actions-file.html#OVERWRITE-LAST-MODIFIED">overwrite-last-modified</a></tt>.</p>
1106 <dt>Example usage (section):</dt>
1108 <table border="0" bgcolor="#E0E0E0" width="90%">
1111 <pre class="SCREEN"># Let the browser revalidate cached documents but don't
1112 # allow the server to use the revalidation headers for user tracking.
1113 {+hide-if-modified-since{-60} \
1114 +overwrite-last-modified{randomize} \
1115 +crunch-if-none-match}
1125 <h4 class="SECT3"><a name="CRUNCH-INCOMING-COOKIES" id="CRUNCH-INCOMING-COOKIES">8.5.9.
1126 crunch-incoming-cookies</a></h4>
1127 <div class="VARIABLELIST">
1129 <dt>Typical use:</dt>
1131 <p>Prevent the web server from setting HTTP cookies on your system</p>
1135 <p>Deletes any <span class="QUOTE">"Set-Cookie:"</span> HTTP headers from server replies.</p>
1147 <p>This action is only concerned with <span class="emphasis"><i class="EMPHASIS">incoming</i></span> HTTP
1148 cookies. For <span class="emphasis"><i class="EMPHASIS">outgoing</i></span> HTTP cookies, use <tt class=
1149 "LITERAL"><a href="actions-file.html#CRUNCH-OUTGOING-COOKIES">crunch-outgoing-cookies</a></tt>. Use
1150 <span class="emphasis"><i class="EMPHASIS">both</i></span> to disable HTTP cookies completely.</p>
1151 <p>It makes <span class="emphasis"><i class="EMPHASIS">no sense at all</i></span> to use this action in
1152 conjunction with the <tt class="LITERAL"><a href=
1153 "actions-file.html#SESSION-COOKIES-ONLY">session-cookies-only</a></tt> action, since it would prevent the
1154 session cookies from being set. See also <tt class="LITERAL"><a href=
1155 "actions-file.html#FILTER-CONTENT-COOKIES">filter-content-cookies</a></tt>.</p>
1157 <dt>Example usage:</dt>
1159 <table border="0" bgcolor="#E0E0E0" width="90%">
1162 <pre class="SCREEN">+crunch-incoming-cookies</pre>
1171 <h4 class="SECT3"><a name="CRUNCH-SERVER-HEADER" id="CRUNCH-SERVER-HEADER">8.5.10.
1172 crunch-server-header</a></h4>
1173 <div class="VARIABLELIST">
1175 <dt>Typical use:</dt>
1177 <p>Remove a server header <span class="APPLICATION">Privoxy</span> has no dedicated action for.</p>
1181 <p>Deletes every header sent by the server that contains the string the user supplied as parameter.</p>
1185 <p>Parameterized.</p>
1193 <p>This action allows you to block server headers for which no dedicated <span class=
1194 "APPLICATION">Privoxy</span> action exists. <span class="APPLICATION">Privoxy</span> will remove every
1195 server header that contains the string you supplied as parameter.</p>
1196 <p>Regular expressions are <span class="emphasis"><i class="EMPHASIS">not supported</i></span> and you
1197 can't use this action to block different headers in the same request, unless they contain the same
1199 <p><tt class="LITERAL">crunch-server-header</tt> is only meant for quick tests. If you have to block
1200 several different headers, or only want to modify parts of them, you should use a custom <tt class=
1201 "LITERAL"><a href="actions-file.html#SERVER-HEADER-FILTER">server-header filter</a></tt>.</p>
1202 <div class="WARNING">
1203 <table class="WARNING" border="1" width="90%">
1205 <td align="center"><b>Warning</b></td>
1209 <p>Don't block any header without understanding the consequences.</p>
1215 <dt>Example usage (section):</dt>
1217 <table border="0" bgcolor="#E0E0E0" width="90%">
1220 <pre class="SCREEN"># Crunch server headers that try to prevent caching
1221 { +crunch-server-header{no-cache} }
1231 <h4 class="SECT3"><a name="CRUNCH-OUTGOING-COOKIES" id="CRUNCH-OUTGOING-COOKIES">8.5.11.
1232 crunch-outgoing-cookies</a></h4>
1233 <div class="VARIABLELIST">
1235 <dt>Typical use:</dt>
1237 <p>Prevent the web server from reading any HTTP cookies from your system</p>
1241 <p>Deletes any <span class="QUOTE">"Cookie:"</span> HTTP headers from client requests.</p>
1253 <p>This action is only concerned with <span class="emphasis"><i class="EMPHASIS">outgoing</i></span> HTTP
1254 cookies. For <span class="emphasis"><i class="EMPHASIS">incoming</i></span> HTTP cookies, use <tt class=
1255 "LITERAL"><a href="actions-file.html#CRUNCH-INCOMING-COOKIES">crunch-incoming-cookies</a></tt>. Use
1256 <span class="emphasis"><i class="EMPHASIS">both</i></span> to disable HTTP cookies completely.</p>
1257 <p>It makes <span class="emphasis"><i class="EMPHASIS">no sense at all</i></span> to use this action in
1258 conjunction with the <tt class="LITERAL"><a href=
1259 "actions-file.html#SESSION-COOKIES-ONLY">session-cookies-only</a></tt> action, since it would prevent the
1260 session cookies from being read.</p>
1262 <dt>Example usage:</dt>
1264 <table border="0" bgcolor="#E0E0E0" width="90%">
1267 <pre class="SCREEN">+crunch-outgoing-cookies</pre>
1276 <h4 class="SECT3"><a name="DEANIMATE-GIFS" id="DEANIMATE-GIFS">8.5.12. deanimate-gifs</a></h4>
1277 <div class="VARIABLELIST">
1279 <dt>Typical use:</dt>
1281 <p>Stop those annoying, distracting animated GIF images.</p>
1285 <p>De-animate GIF animations, i.e. reduce them to their first or last image.</p>
1289 <p>Parameterized.</p>
1293 <p><span class="QUOTE">"last"</span> or <span class="QUOTE">"first"</span></p>
1297 <p>This will also shrink the images considerably (in bytes, not pixels!). If the option <span class=
1298 "QUOTE">"first"</span> is given, the first frame of the animation is used as the replacement. If
1299 <span class="QUOTE">"last"</span> is given, the last frame of the animation is used instead, which
1300 probably makes more sense for most banner animations, but also has the risk of not showing the entire
1301 last frame (if it is only a delta to an earlier frame).</p>
1302 <p>You can safely use this action with patterns that will also match non-GIF objects, because no attempt
1303 will be made at anything that doesn't look like a GIF.</p>
1305 <dt>Example usage:</dt>
1307 <table border="0" bgcolor="#E0E0E0" width="90%">
1310 <pre class="SCREEN">+deanimate-gifs{last}</pre>
1319 <h4 class="SECT3"><a name="DELAY-RESPONSE" id="DELAY-RESPONSE">8.5.13. delay-response</a></h4>
1320 <div class="VARIABLELIST">
1322 <dt>Typical use:</dt>
1324 <p>Delay responses to the client to reduce the load</p>
1328 <p>Delays responses to the client by sending the response in ca. 10 byte chunks.</p>
1332 <p>Parameterized.</p>
1336 <p><span class="QUOTE">"Number of milliseconds"</span></p>
1340 <p>Sometimes when JavaScript code is used to fetch advertisements it doesn't respect Privoxy's blocks and
1341 retries to fetch the same resource again causing unnecessary load on the client.</p>
1342 <p>This action delays responses to the client and can be combined with <tt class="LITERAL"><a href=
1343 "actions-file.html#BLOCK">blocks</a></tt> to slow down the JavaScript code, thus reducing the load on the
1345 <p>When used without <tt class="LITERAL"><a href="actions-file.html#BLOCK">blocks</a></tt> the action can
1346 also be used to simulate a slow internet connection.</p>
1348 <dt>Example usage:</dt>
1350 <table border="0" bgcolor="#E0E0E0" width="90%">
1353 <pre class="SCREEN">+delay-response{100}</pre>
1362 <h4 class="SECT3"><a name="DOWNGRADE-HTTP-VERSION" id="DOWNGRADE-HTTP-VERSION">8.5.14.
1363 downgrade-http-version</a></h4>
1364 <div class="VARIABLELIST">
1366 <dt>Typical use:</dt>
1368 <p>Work around (very rare) problems with HTTP/1.1</p>
1372 <p>Downgrades HTTP/1.1 client requests and server replies to HTTP/1.0.</p>
1384 <p>This is a left-over from the time when <span class="APPLICATION">Privoxy</span> didn't support
1385 important HTTP/1.1 features well. It is left here for the unlikely case that you experience
1386 HTTP/1.1-related problems with some server out there.</p>
1387 <p>Note that enabling this action is only a workaround. It should not be enabled for sites that work
1388 without it. While it shouldn't break any pages, it has an (usually negative) performance impact.</p>
1389 <p>If you come across a site where enabling this action helps, please report it, so the cause of the
1390 problem can be analyzed. If the problem turns out to be caused by a bug in <span class=
1391 "APPLICATION">Privoxy</span> it should be fixed so the following release works without the work
1394 <dt>Example usage (section):</dt>
1396 <table border="0" bgcolor="#E0E0E0" width="90%">
1399 <pre class="SCREEN">{+downgrade-http-version}
1400 problem-host.example.com</pre>
1409 <h4 class="SECT3"><a name="EXTERNAL-FILTER" id="EXTERNAL-FILTER">8.5.15. external-filter</a></h4>
1410 <div class="VARIABLELIST">
1412 <dt>Typical use:</dt>
1414 <p>Modify content using a programming language of your choice.</p>
1418 <p>All instances of text-based type, most notably HTML and JavaScript, to which this action applies, can
1419 be filtered on-the-fly through the specified external filter. By default plain text documents are
1420 exempted from filtering, because web servers often use the <tt class="LITERAL">text/plain</tt> MIME type
1421 for all files whose type they don't know.)</p>
1429 <p>The name of an external content filter, as defined in the <a href="filter-file.html">filter file</a>.
1430 External filters can be defined in one or more files as defined by the <tt class="LITERAL"><a href=
1431 "config.html#FILTERFILE">filterfile</a></tt> option in the <a href="config.html">config file</a>.</p>
1432 <p>When used in its negative form, and without parameters, <span class="emphasis"><i class=
1433 "EMPHASIS">all</i></span> filtering with external filters is completely disabled.</p>
1437 <p>External filters are scripts or programs that can modify the content in case common <tt class=
1438 "LITERAL"><a href="actions-file.html#FILTER">filters</a></tt> aren't powerful enough. With the exception
1439 that this action doesn't use pcrs-based filters, the notes in the <tt class="LITERAL"><a href=
1440 "actions-file.html#FILTER">filter</a></tt> section apply.</p>
1441 <div class="WARNING">
1442 <table class="WARNING" border="1" width="90%">
1444 <td align="center"><b>Warning</b></td>
1448 <p>Currently external filters are executed with <span class="APPLICATION">Privoxy</span>'s
1449 privileges. Only use external filters you understand and trust.</p>
1454 <p>This feature is experimental, the <tt class="LITERAL"><a href=
1455 "filter-file.html#EXTERNAL-FILTER-SYNTAX">syntax</a></tt> may change in the future.</p>
1457 <dt>Example usage:</dt>
1459 <table border="0" bgcolor="#E0E0E0" width="90%">
1462 <pre class="SCREEN">+external-filter{fancy-filter}</pre>
1471 <h4 class="SECT3"><a name="FAST-REDIRECTS" id="FAST-REDIRECTS">8.5.16. fast-redirects</a></h4>
1472 <div class="VARIABLELIST">
1474 <dt>Typical use:</dt>
1476 <p>Fool some click-tracking scripts and speed up indirect links.</p>
1480 <p>Detects redirection URLs and redirects the browser without contacting the redirection server
1485 <p>Parameterized.</p>
1491 <p><span class="QUOTE">"simple-check"</span> to just search for the string <span class=
1492 "QUOTE">"http://"</span> to detect redirection URLs.</p>
1495 <p><span class="QUOTE">"check-decoded-url"</span> to decode URLs (if necessary) before searching for
1496 redirection URLs.</p>
1502 <p>Many sites, like yahoo.com, don't just link to other sites. Instead, they will link to some script on
1503 their own servers, giving the destination as a parameter, which will then redirect you to the final
1504 target. URLs resulting from this scheme typically look like: <span class=
1505 "QUOTE">"http://www.example.org/click-tracker.cgi?target=http%3a//www.example.net/"</span>.</p>
1506 <p>Sometimes, there are even multiple consecutive redirects encoded in the URL. These redirections via
1507 scripts make your web browsing more traceable, since the server from which you follow such a link can see
1508 where you go to. Apart from that, valuable bandwidth and time is wasted, while your browser asks the
1509 server for one redirect after the other. Plus, it feeds the advertisers.</p>
1510 <p>This feature is currently not very smart and is scheduled for improvement. If it is enabled by
1511 default, you will have to create some exceptions to this action. It can lead to failures in several
1513 <p>Not every URLs with other URLs as parameters is evil. Some sites offer a real service that requires
1514 this information to work. For example a validation service needs to know, which document to validate.
1515 <tt class="LITERAL">fast-redirects</tt> assumes that every URL parameter that looks like another URL is a
1516 redirection target, and will always redirect to the last one. Most of the time the assumption is correct,
1517 but if it isn't, the user gets redirected anyway.</p>
1518 <p>Another failure occurs if the URL contains other parameters after the URL parameter. The URL:
1519 <span class="QUOTE">"http://www.example.org/?redirect=http%3a//www.example.net/&foo=bar"</span>.
1520 contains the redirection URL <span class="QUOTE">"http://www.example.net/"</span>, followed by another
1521 parameter. <tt class="LITERAL">fast-redirects</tt> doesn't know that and will cause a redirect to
1522 <span class="QUOTE">"http://www.example.net/&foo=bar"</span>. Depending on the target server
1523 configuration, the parameter will be silently ignored or lead to a <span class="QUOTE">"page not
1524 found"</span> error. You can prevent this problem by first using the <tt class="LITERAL"><a href=
1525 "actions-file.html#REDIRECT">redirect</a></tt> action to remove the last part of the URL, but it requires
1526 a little effort.</p>
1527 <p>To detect a redirection URL, <tt class="LITERAL">fast-redirects</tt> only looks for the string
1528 <span class="QUOTE">"http://"</span>, either in plain text (invalid but often used) or encoded as
1529 <span class="QUOTE">"http%3a//"</span>. Some sites use their own URL encoding scheme, encrypt the address
1530 of the target server or replace it with a database id. In these cases <tt class=
1531 "LITERAL">fast-redirects</tt> is fooled and the request reaches the redirection server where it probably
1534 <dt>Example usage:</dt>
1536 <table border="0" bgcolor="#E0E0E0" width="90%">
1539 <pre class="SCREEN"> { +fast-redirects{simple-check} }
1542 { +fast-redirects{check-decoded-url} }
1543 another.example.com/testing</pre>
1552 <h4 class="SECT3"><a name="FILTER" id="FILTER">8.5.17. filter</a></h4>
1553 <div class="VARIABLELIST">
1555 <dt>Typical use:</dt>
1557 <p>Get rid of HTML and JavaScript annoyances, banner advertisements (by size), do fun text replacements,
1558 add personalized effects, etc.</p>
1562 <p>All instances of text-based type, most notably HTML and JavaScript, to which this action applies, can
1563 be filtered on-the-fly through the specified regular expression based substitutions. (Note: as of version
1564 3.0.3 plain text documents are exempted from filtering, because web servers often use the <tt class=
1565 "LITERAL">text/plain</tt> MIME type for all files whose type they don't know.)</p>
1573 <p>The name of a content filter, as defined in the <a href="filter-file.html">filter file</a>. Filters
1574 can be defined in one or more files as defined by the <tt class="LITERAL"><a href=
1575 "config.html#FILTERFILE">filterfile</a></tt> option in the <a href="config.html">config file</a>.
1576 <tt class="FILENAME">default.filter</tt> is the collection of filters supplied by the developers. Locally
1577 defined filters should go in their own file, such as <tt class="FILENAME">user.filter</tt>.</p>
1578 <p>When used in its negative form, and without parameters, <span class="emphasis"><i class=
1579 "EMPHASIS">all</i></span> filtering is completely disabled.</p>
1583 <p>For your convenience, there are a number of pre-defined filters available in the distribution filter
1584 file that you can use. See the examples below for a list.</p>
1585 <p>Filtering requires buffering the page content, which may appear to slow down page rendering since
1586 nothing is displayed until all content has passed the filters. (The total time until the page is
1587 completely rendered doesn't change much, but it may be perceived as slower since the page is not
1588 incrementally displayed.) This effect will be more noticeable on slower connections.</p>
1589 <p><span class="QUOTE">"Rolling your own"</span> filters requires a knowledge of <a href=
1590 "https://en.wikipedia.org/wiki/Regular_expressions" target="_top"><span class="QUOTE">"Regular
1591 Expressions"</span></a> and <a href="https://en.wikipedia.org/wiki/Html" target="_top"><span class=
1592 "QUOTE">"HTML"</span></a>. This is very powerful feature, and potentially very intrusive. Filters should
1593 be used with caution, and where an equivalent <span class="QUOTE">"action"</span> is not available.</p>
1594 <p>The amount of data that can be filtered is limited to the <tt class="LITERAL"><a href=
1595 "config.html#BUFFER-LIMIT">buffer-limit</a></tt> option in the main <a href="config.html">config
1596 file</a>. The default is 4096 KB (4 Megs). Once this limit is exceeded, the buffered data, and all
1597 pending data, is passed through unfiltered.</p>
1598 <p>Inappropriate MIME types, such as zipped files, are not filtered at all. (Again, only text-based types
1599 except plain text). Encrypted SSL data (from HTTPS servers) cannot be filtered either, since this would
1600 violate the integrity of the secure transaction. In some situations it might be necessary to protect
1601 certain text, like source code, from filtering by defining appropriate <tt class="LITERAL">-filter</tt>
1603 <p>Compressed content can't be filtered either, but if <span class="APPLICATION">Privoxy</span> is
1604 compiled with zlib support and a supported compression algorithm is used (gzip or deflate), <span class=
1605 "APPLICATION">Privoxy</span> can first decompress the content and then filter it.</p>
1606 <p>If you use a <span class="APPLICATION">Privoxy</span> version without zlib support, but want filtering
1607 to work on as much documents as possible, even those that would normally be sent compressed, you must use
1608 the <tt class="LITERAL"><a href="actions-file.html#PREVENT-COMPRESSION">prevent-compression</a></tt>
1609 action in conjunction with <tt class="LITERAL">filter</tt>.</p>
1610 <p>Content filtering can achieve some of the same effects as the <tt class="LITERAL"><a href=
1611 "actions-file.html#BLOCK">block</a></tt> action, i.e. it can be used to block ads and banners. But the
1612 mechanism works quite differently. One effective use, is to block ad banners based on their size (see
1613 below), since many of these seem to be somewhat standardized.</p>
1614 <p><a href="contact.html">Feedback</a> with suggestions for new or improved filters is particularly
1616 <p>The below list has only the names and a one-line description of each predefined filter. There are
1617 <a href="filter-file.html#PREDEFINED-FILTERS">more verbose explanations</a> of what these filters do in
1618 the <a href="filter-file.html">filter file chapter</a>.</p>
1620 <dt>Example usage (with filters from the distribution <tt class="FILENAME">default.filter</tt> file). See
1621 <a href="filter-file.html#PREDEFINED-FILTERS">the Predefined Filters section</a> for more explanation on
1624 <p><a name="FILTER-JS-ANNOYANCES" id="FILTER-JS-ANNOYANCES"></a></p>
1625 <table border="0" bgcolor="#E0E0E0" width="90%">
1629 "SCREEN">+filter{js-annoyances} # Get rid of particularly annoying JavaScript abuse.</pre>
1633 <p><a name="FILTER-JS-EVENTS" id="FILTER-JS-EVENTS"></a></p>
1634 <table border="0" bgcolor="#E0E0E0" width="90%">
1638 "SCREEN">+filter{js-events} # Kill JavaScript event bindings and timers (Radically destructive! Only for extra nasty sites).</pre>
1642 <p><a name="FILTER-HTML-ANNOYANCES" id="FILTER-HTML-ANNOYANCES"></a></p>
1643 <table border="0" bgcolor="#E0E0E0" width="90%">
1647 "SCREEN">+filter{html-annoyances} # Get rid of particularly annoying HTML abuse.</pre>
1651 <p><a name="FILTER-CONTENT-COOKIES" id="FILTER-CONTENT-COOKIES"></a></p>
1652 <table border="0" bgcolor="#E0E0E0" width="90%">
1656 "SCREEN">+filter{content-cookies} # Kill cookies that come in the HTML or JS content.</pre>
1660 <p><a name="FILTER-REFRESH-TAGS" id="FILTER-REFRESH-TAGS"></a></p>
1661 <table border="0" bgcolor="#E0E0E0" width="90%">
1665 "SCREEN">+filter{refresh-tags} # Kill automatic refresh tags if refresh time is larger than 9 seconds.</pre>
1669 <p><a name="FILTER-UNSOLICITED-POPUPS" id="FILTER-UNSOLICITED-POPUPS"></a></p>
1670 <table border="0" bgcolor="#E0E0E0" width="90%">
1673 <pre class="SCREEN">+filter{unsolicited-popups} # Disable only unsolicited pop-up windows.</pre>
1677 <p><a name="FILTER-ALL-POPUPS" id="FILTER-ALL-POPUPS"></a></p>
1678 <table border="0" bgcolor="#E0E0E0" width="90%">
1681 <pre class="SCREEN">+filter{all-popups} # Kill all popups in JavaScript and HTML.</pre>
1685 <p><a name="FILTER-IMG-REORDER" id="FILTER-IMG-REORDER"></a></p>
1686 <table border="0" bgcolor="#E0E0E0" width="90%">
1690 "SCREEN">+filter{img-reorder} # Reorder attributes in <img> tags to make the banners-by-* filters more effective.</pre>
1694 <p><a name="FILTER-BANNERS-BY-SIZE" id="FILTER-BANNERS-BY-SIZE"></a></p>
1695 <table border="0" bgcolor="#E0E0E0" width="90%">
1698 <pre class="SCREEN">+filter{banners-by-size} # Kill banners by size.</pre>
1702 <p><a name="FILTER-BANNERS-BY-LINK" id="FILTER-BANNERS-BY-LINK"></a></p>
1703 <table border="0" bgcolor="#E0E0E0" width="90%">
1707 "SCREEN">+filter{banners-by-link} # Kill banners by their links to known clicktrackers.</pre>
1711 <p><a name="FILTER-WEBBUGS" id="FILTER-WEBBUGS"></a></p>
1712 <table border="0" bgcolor="#E0E0E0" width="90%">
1716 "SCREEN">+filter{webbugs} # Squish WebBugs (1x1 invisible GIFs used for user tracking).</pre>
1720 <p><a name="FILTER-TINY-TEXTFORMS" id="FILTER-TINY-TEXTFORMS"></a></p>
1721 <table border="0" bgcolor="#E0E0E0" width="90%">
1725 "SCREEN">+filter{tiny-textforms} # Extend those tiny textareas up to 40x80 and kill the hard wrap.</pre>
1729 <p><a name="FILTER-JUMPING-WINDOWS" id="FILTER-JUMPING-WINDOWS"></a></p>
1730 <table border="0" bgcolor="#E0E0E0" width="90%">
1734 "SCREEN">+filter{jumping-windows} # Prevent windows from resizing and moving themselves.</pre>
1738 <p><a name="FILTER-FRAMESET-BORDERS" id="FILTER-FRAMESET-BORDERS"></a></p>
1739 <table border="0" bgcolor="#E0E0E0" width="90%">
1743 "SCREEN">+filter{frameset-borders} # Give frames a border and make them resizable.</pre>
1747 <p><a name="FILTER-IFRAMES" id="FILTER-IFRAMES"></a></p>
1748 <table border="0" bgcolor="#E0E0E0" width="90%">
1752 "SCREEN">+filter{iframes} # Removes all detected iframes. Should only be enabled for individual sites.</pre>
1756 <p><a name="FILTER-DEMORONIZER" id="FILTER-DEMORONIZER"></a></p>
1757 <table border="0" bgcolor="#E0E0E0" width="90%">
1761 "SCREEN">+filter{demoronizer} # Fix MS's non-standard use of standard charsets.</pre>
1765 <p><a name="FILTER-SHOCKWAVE-FLASH" id="FILTER-SHOCKWAVE-FLASH"></a></p>
1766 <table border="0" bgcolor="#E0E0E0" width="90%">
1769 <pre class="SCREEN">+filter{shockwave-flash} # Kill embedded Shockwave Flash objects.</pre>
1773 <p><a name="FILTER-QUICKTIME-KIOSKMODE" id="FILTER-QUICKTIME-KIOSKMODE"></a></p>
1774 <table border="0" bgcolor="#E0E0E0" width="90%">
1777 <pre class="SCREEN">+filter{quicktime-kioskmode} # Make Quicktime movies saveable.</pre>
1781 <p><a name="FILTER-FUN" id="FILTER-FUN"></a></p>
1782 <table border="0" bgcolor="#E0E0E0" width="90%">
1786 "SCREEN">+filter{fun} # Text replacements for subversive browsing fun!</pre>
1790 <p><a name="FILTER-CRUDE-PARENTAL" id="FILTER-CRUDE-PARENTAL"></a></p>
1791 <table border="0" bgcolor="#E0E0E0" width="90%">
1795 "SCREEN">+filter{crude-parental} # Crude parental filtering. Note that this filter doesn't work reliably.</pre>
1799 <p><a name="FILTER-IE-EXPLOITS" id="FILTER-IE-EXPLOITS"></a></p>
1800 <table border="0" bgcolor="#E0E0E0" width="90%">
1804 "SCREEN">+filter{ie-exploits} # Disable some known Internet Explorer bug exploits.</pre>
1808 <p><a name="FILTER-SITE-SPECIFICS" id="FILTER-SITE-SPECIFICS"></a></p>
1809 <table border="0" bgcolor="#E0E0E0" width="90%">
1813 "SCREEN">+filter{site-specifics} # Cure for site-specific problems. Don't apply generally!</pre>
1817 <p><a name="FILTER-NO-PING" id="FILTER-NO-PING"></a></p>
1818 <table border="0" bgcolor="#E0E0E0" width="90%">
1822 "SCREEN">+filter{no-ping} # Removes non-standard ping attributes in <a> and <area> tags.</pre>
1826 <p><a name="FILTER-GOOGLE" id="FILTER-GOOGLE"></a></p>
1827 <table border="0" bgcolor="#E0E0E0" width="90%">
1831 "SCREEN">+filter{google} # CSS-based block for Google text ads. Also removes a width limitation and the toolbar advertisement.</pre>
1835 <p><a name="FILTER-YAHOO" id="FILTER-YAHOO"></a></p>
1836 <table border="0" bgcolor="#E0E0E0" width="90%">
1840 "SCREEN">+filter{yahoo} # CSS-based block for Yahoo text ads. Also removes a width limitation.</pre>
1844 <p><a name="FILTER-MSN" id="FILTER-MSN"></a></p>
1845 <table border="0" bgcolor="#E0E0E0" width="90%">
1849 "SCREEN">+filter{msn} # CSS-based block for MSN text ads. Also removes tracking URLs and a width limitation.</pre>
1853 <p><a name="FILTER-BLOGSPOT" id="FILTER-BLOGSPOT"></a></p>
1854 <table border="0" bgcolor="#E0E0E0" width="90%">
1858 "SCREEN">+filter{blogspot} # Cleans up some Blogspot blogs. Read the fine print before using this.</pre>
1867 <h4 class="SECT3"><a name="FORCE-TEXT-MODE" id="FORCE-TEXT-MODE">8.5.18. force-text-mode</a></h4>
1868 <div class="VARIABLELIST">
1870 <dt>Typical use:</dt>
1872 <p>Force <span class="APPLICATION">Privoxy</span> to treat a document as if it was in some kind of
1873 <span class="emphasis"><i class="EMPHASIS">text</i></span> format.</p>
1877 <p>Declares a document as text, even if the <span class="QUOTE">"Content-Type:"</span> isn't detected as
1890 <p>As explained <tt class="LITERAL"><a href="actions-file.html#FILTER">above</a></tt>, <span class=
1891 "APPLICATION">Privoxy</span> tries to only filter files that are in some kind of text format. The same
1892 restrictions apply to <tt class="LITERAL"><a href=
1893 "actions-file.html#CONTENT-TYPE-OVERWRITE">content-type-overwrite</a></tt>. <tt class=
1894 "LITERAL">force-text-mode</tt> declares a document as text, without looking at the <span class=
1895 "QUOTE">"Content-Type:"</span> first.</p>
1896 <div class="WARNING">
1897 <table class="WARNING" border="1" width="90%">
1899 <td align="center"><b>Warning</b></td>
1903 <p>Think twice before activating this action. Filtering binary data with regular expressions can
1904 cause file damage.</p>
1910 <dt>Example usage:</dt>
1912 <table border="0" bgcolor="#E0E0E0" width="90%">
1915 <pre class="SCREEN">+force-text-mode</pre>
1924 <h4 class="SECT3"><a name="FORWARD-OVERRIDE" id="FORWARD-OVERRIDE">8.5.19. forward-override</a></h4>
1925 <div class="VARIABLELIST">
1927 <dt>Typical use:</dt>
1929 <p>Change the forwarding settings based on User-Agent or request origin</p>
1933 <p>Overrules the forward directives in the configuration file.</p>
1937 <p>Parameterized.</p>
1943 <p><span class="QUOTE">"forward ."</span> to use a direct connection without any additional
1947 <p><span class="QUOTE">"forward 127.0.0.1:8123"</span> to use the HTTP proxy listening at 127.0.0.1
1951 <p><span class="QUOTE">"forward-socks4a 127.0.0.1:9050 ."</span> to use the socks4a proxy listening
1952 at 127.0.0.1 port 9050. Replace <span class="QUOTE">"forward-socks4a"</span> with <span class=
1953 "QUOTE">"forward-socks4"</span> to use a socks4 connection (with local DNS resolution) instead, use
1954 <span class="QUOTE">"forward-socks5"</span> for socks5 connections (with remote DNS resolution).</p>
1957 <p><span class="QUOTE">"forward-socks4a 127.0.0.1:9050 proxy.example.org:8000"</span> to use the
1958 socks4a proxy listening at 127.0.0.1 port 9050 to reach the HTTP proxy listening at proxy.example.org
1959 port 8000. Replace <span class="QUOTE">"forward-socks4a"</span> with <span class=
1960 "QUOTE">"forward-socks4"</span> to use a socks4 connection (with local DNS resolution) instead, use
1961 <span class="QUOTE">"forward-socks5"</span> for socks5 connections (with remote DNS resolution).</p>
1964 <p><span class="QUOTE">"forward-webserver 127.0.0.1:80"</span> to use the HTTP server listening at
1965 127.0.0.1 port 80 without adjusting the request headers.</p>
1966 <p>This makes it more convenient to use Privoxy to make existing websites available as onion services
1968 <p>Many websites serve content with hardcoded URLs and can't be easily adjusted to change the domain
1969 based on the one used by the client.</p>
1970 <p>Putting Privoxy between Tor and the webserver (or an stunnel that forwards to the webserver)
1971 allows to rewrite headers and content to make client and server happy at the same time.</p>
1972 <p>Using Privoxy for webservers that are only reachable through onion addresses and whose location is
1973 supposed to be secret is not recommended and should not be necessary anyway.</p>
1979 <p>This action takes parameters similar to the <a href="config.html#FORWARDING">forward</a> directives in
1980 the configuration file, but without the URL pattern. It can be used as replacement, but normally it's
1981 only used in cases where matching based on the request URL isn't sufficient.</p>
1982 <div class="WARNING">
1983 <table class="WARNING" border="1" width="90%">
1985 <td align="center"><b>Warning</b></td>
1989 <p>Please read the description for the <a href="config.html#FORWARDING">forward</a> directives
1990 before using this action. Forwarding to the wrong people will reduce your privacy and increase
1991 the chances of man-in-the-middle attacks.</p>
1992 <p>If the ports are missing or invalid, default values will be used. This might change in the
1993 future and you shouldn't rely on it. Otherwise incorrect syntax causes Privoxy to exit. Due to
1994 design limitations, invalid parameter syntax isn't detected until the action is used the first
1996 <p>Use the <a href="http://config.privoxy.org/show-url-info" target="_top">show-url-info CGI
1997 page</a> to verify that your forward settings do what you thought the do.</p>
2003 <dt>Example usage:</dt>
2005 <table border="0" bgcolor="#E0E0E0" width="90%">
2008 <pre class="SCREEN"># Use an ssh tunnel for requests previously tagged as
2009 # <span class="QUOTE">"User-Agent: fetch libfetch/2.0"</span> and make sure
2010 # resuming downloads continues to work.
2012 # This way you can continue to use Tor for your normal browsing,
2013 # without overloading the Tor network with your FreeBSD ports updates
2014 # or downloads of bigger files like ISOs.
2016 # Note that HTTP headers are easy to fake and therefore their
2017 # values are as (un)trustworthy as your clients and users.
2018 {+forward-override{forward-socks5 10.0.0.2:2222 .} \
2019 -hide-if-modified-since \
2020 -overwrite-last-modified \
2022 TAG:^User-Agent: fetch libfetch/2\.0$</pre>
2031 <h4 class="SECT3"><a name="HANDLE-AS-EMPTY-DOCUMENT" id="HANDLE-AS-EMPTY-DOCUMENT">8.5.20.
2032 handle-as-empty-document</a></h4>
2033 <div class="VARIABLELIST">
2035 <dt>Typical use:</dt>
2037 <p>Mark URLs that should be replaced by empty documents <span class="emphasis"><i class="EMPHASIS">if
2038 they get blocked</i></span></p>
2042 <p>This action alone doesn't do anything noticeable. It just marks URLs. If the <tt class=
2043 "LITERAL"><a href="actions-file.html#BLOCK">block</a></tt> action <span class="emphasis"><i class=
2044 "EMPHASIS">also applies</i></span>, the presence or absence of this mark decides whether an HTML
2045 <span class="QUOTE">"BLOCKED"</span> page, or an empty document will be sent to the client as a
2046 substitute for the blocked content. The <span class="emphasis"><i class="EMPHASIS">empty</i></span>
2047 document isn't literally empty, but actually contains a single space.</p>
2059 <p>Some browsers complain about syntax errors if JavaScript documents are blocked with <span class=
2060 "APPLICATION">Privoxy's</span> default HTML page; this option can be used to silence them. And of course
2061 this action can also be used to eliminate the <span class="APPLICATION">Privoxy</span> BLOCKED message in
2063 <p>The content type for the empty document can be specified with <tt class="LITERAL"><a href=
2064 "actions-file.html#CONTENT-TYPE-OVERWRITE">content-type-overwrite{}</a></tt>, but usually this isn't
2067 <dt>Example usage:</dt>
2069 <table border="0" bgcolor="#E0E0E0" width="90%">
2072 <pre class="SCREEN"># Block all documents on example.org that end with ".js",
2073 # but send an empty document instead of the usual HTML message.
2074 {+block{Blocked JavaScript} +handle-as-empty-document}
2075 example.org/.*\.js$</pre>
2084 <h4 class="SECT3"><a name="HANDLE-AS-IMAGE" id="HANDLE-AS-IMAGE">8.5.21. handle-as-image</a></h4>
2085 <div class="VARIABLELIST">
2087 <dt>Typical use:</dt>
2089 <p>Mark URLs as belonging to images (so they'll be replaced by images <span class="emphasis"><i class=
2090 "EMPHASIS">if they do get blocked</i></span>, rather than HTML pages)</p>
2094 <p>This action alone doesn't do anything noticeable. It just marks URLs as images. If the <tt class=
2095 "LITERAL"><a href="actions-file.html#BLOCK">block</a></tt> action <span class="emphasis"><i class=
2096 "EMPHASIS">also applies</i></span>, the presence or absence of this mark decides whether an HTML
2097 <span class="QUOTE">"blocked"</span> page, or a replacement image (as determined by the <tt class=
2098 "LITERAL"><a href="actions-file.html#SET-IMAGE-BLOCKER">set-image-blocker</a></tt> action) will be sent
2099 to the client as a substitute for the blocked content.</p>
2111 <p>The below generic example section is actually part of <tt class="FILENAME">default.action</tt>. It
2112 marks all URLs with well-known image file name extensions as images and should be left intact.</p>
2113 <p>Users will probably only want to use the handle-as-image action in conjunction with <tt class=
2114 "LITERAL"><a href="actions-file.html#BLOCK">block</a></tt>, to block sources of banners, whose URLs don't
2115 reflect the file type, like in the second example section.</p>
2116 <p>Note that you cannot treat HTML pages as images in most cases. For instance, (in-line) ad frames
2117 require an HTML page to be sent, or they won't display properly. Forcing <tt class=
2118 "LITERAL">handle-as-image</tt> in this situation will not replace the ad frame with an image, but lead to
2121 <dt>Example usage (sections):</dt>
2123 <table border="0" bgcolor="#E0E0E0" width="90%">
2126 <pre class="SCREEN"># Generic image extensions:
2129 /.*\.(gif|jpg|jpeg|png|bmp|ico)$
2131 # These don't look like images, but they're banners and should be
2132 # blocked as images:
2134 {+block{Nasty banners.} +handle-as-image}
2135 nasty-banner-server.example.com/junk.cgi\?output=trash</pre>
2144 <h4 class="SECT3"><a name="HIDE-ACCEPT-LANGUAGE" id="HIDE-ACCEPT-LANGUAGE">8.5.22.
2145 hide-accept-language</a></h4>
2146 <div class="VARIABLELIST">
2148 <dt>Typical use:</dt>
2150 <p>Pretend to use different language settings.</p>
2154 <p>Deletes or replaces the <span class="QUOTE">"Accept-Language:"</span> HTTP header in client
2159 <p>Parameterized.</p>
2163 <p>Keyword: <span class="QUOTE">"block"</span>, or any user defined value.</p>
2167 <p>Faking the browser's language settings can be useful to make a foreign User-Agent set with <tt class=
2168 "LITERAL"><a href="actions-file.html#HIDE-USER-AGENT">hide-user-agent</a></tt> more believable.</p>
2169 <p>However some sites with content in different languages check the <span class=
2170 "QUOTE">"Accept-Language:"</span> to decide which one to take by default. Sometimes it isn't possible to
2171 later switch to another language without changing the <span class="QUOTE">"Accept-Language:"</span>
2173 <p>Therefore it's a good idea to either only change the <span class="QUOTE">"Accept-Language:"</span>
2174 header to languages you understand, or to languages that aren't wide spread.</p>
2175 <p>Before setting the <span class="QUOTE">"Accept-Language:"</span> header to a rare language, you should
2176 consider that it helps to make your requests unique and thus easier to trace. If you don't plan to change
2177 this header frequently, you should stick to a common language.</p>
2179 <dt>Example usage (section):</dt>
2181 <table border="0" bgcolor="#E0E0E0" width="90%">
2184 <pre class="SCREEN"># Pretend to use Canadian language settings.
2185 {+hide-accept-language{en-ca} \
2186 +hide-user-agent{Mozilla/5.0 (X11; U; OpenBSD i386; en-CA; rv:1.8.0.4) Gecko/20060628 Firefox/1.5.0.4} \
2197 <h4 class="SECT3"><a name="HIDE-CONTENT-DISPOSITION" id="HIDE-CONTENT-DISPOSITION">8.5.23.
2198 hide-content-disposition</a></h4>
2199 <div class="VARIABLELIST">
2201 <dt>Typical use:</dt>
2203 <p>Prevent download menus for content you prefer to view inside the browser.</p>
2207 <p>Deletes or replaces the <span class="QUOTE">"Content-Disposition:"</span> HTTP header set by some
2212 <p>Parameterized.</p>
2216 <p>Keyword: <span class="QUOTE">"block"</span>, or any user defined value.</p>
2220 <p>Some servers set the <span class="QUOTE">"Content-Disposition:"</span> HTTP header for documents they
2221 assume you want to save locally before viewing them. The <span class=
2222 "QUOTE">"Content-Disposition:"</span> header contains the file name the browser is supposed to use by
2224 <p>In most browsers that understand this header, it makes it impossible to <span class=
2225 "emphasis"><i class="EMPHASIS">just view</i></span> the document, without downloading it first, even if
2226 it's just a simple text file or an image.</p>
2227 <p>Removing the <span class="QUOTE">"Content-Disposition:"</span> header helps to prevent this annoyance,
2228 but some browsers additionally check the <span class="QUOTE">"Content-Type:"</span> header, before they
2229 decide if they can display a document without saving it first. In these cases, you have to change this
2230 header as well, before the browser stops displaying download menus.</p>
2231 <p>It is also possible to change the server's file name suggestion to another one, but in most cases it
2232 isn't worth the time to set it up.</p>
2233 <p>This action will probably be removed in the future, use server-header filters instead.</p>
2235 <dt>Example usage:</dt>
2237 <table border="0" bgcolor="#E0E0E0" width="90%">
2240 <pre class="SCREEN"># Disarm the download link in Sourceforge's patch tracker
2242 +content-type-overwrite{text/plain}\
2243 +hide-content-disposition{block} }
2244 .sourceforge.net/tracker/download\.php</pre>
2253 <h4 class="SECT3"><a name="HIDE-IF-MODIFIED-SINCE" id="HIDE-IF-MODIFIED-SINCE">8.5.24.
2254 hide-if-modified-since</a></h4>
2255 <div class="VARIABLELIST">
2257 <dt>Typical use:</dt>
2259 <p>Prevent yet another way to track the user's steps between sessions.</p>
2263 <p>Deletes the <span class="QUOTE">"If-Modified-Since:"</span> HTTP client header or modifies its
2268 <p>Parameterized.</p>
2272 <p>Keyword: <span class="QUOTE">"block"</span>, or a user defined value that specifies a range of
2277 <p>Removing this header is useful for filter testing, where you want to force a real reload instead of
2278 getting status code <span class="QUOTE">"304"</span>, which would cause the browser to use a cached copy
2280 <p>Instead of removing the header, <tt class="LITERAL">hide-if-modified-since</tt> can also add or
2281 subtract a random amount of time to/from the header's value. You specify a range of minutes where the
2282 random factor should be chosen from and <span class="APPLICATION">Privoxy</span> does the rest. A
2283 negative value means subtracting, a positive value adding.</p>
2284 <p>Randomizing the value of the <span class="QUOTE">"If-Modified-Since:"</span> makes it less likely that
2285 the server can use the time as a cookie replacement, but you will run into caching problems if the random
2286 range is too high.</p>
2287 <p>It is a good idea to only use a small negative value and let <tt class="LITERAL"><a href=
2288 "actions-file.html#OVERWRITE-LAST-MODIFIED">overwrite-last-modified</a></tt> handle the greater
2290 <p>It is also recommended to use this action together with <tt class="LITERAL"><a href=
2291 "actions-file.html#CRUNCH-IF-NONE-MATCH">crunch-if-none-match</a></tt>, otherwise it's more or less
2294 <dt>Example usage (section):</dt>
2296 <table border="0" bgcolor="#E0E0E0" width="90%">
2299 <pre class="SCREEN"># Let the browser revalidate but make tracking based on the time less likely.
2300 {+hide-if-modified-since{-60} \
2301 +overwrite-last-modified{randomize} \
2302 +crunch-if-none-match}
2312 <h4 class="SECT3"><a name="HIDE-FROM-HEADER" id="HIDE-FROM-HEADER">8.5.25. hide-from-header</a></h4>
2313 <div class="VARIABLELIST">
2315 <dt>Typical use:</dt>
2317 <p>Keep your (old and ill) browser from telling web servers your email address</p>
2321 <p>Deletes any existing <span class="QUOTE">"From:"</span> HTTP header, or replaces it with the specified
2326 <p>Parameterized.</p>
2330 <p>Keyword: <span class="QUOTE">"block"</span>, or any user defined value.</p>
2334 <p>The keyword <span class="QUOTE">"block"</span> will completely remove the header (not to be confused
2335 with the <tt class="LITERAL"><a href="actions-file.html#BLOCK">block</a></tt> action).</p>
2336 <p>Alternately, you can specify any value you prefer to be sent to the web server. If you do, it is a
2337 matter of fairness not to use any address that is actually used by a real person.</p>
2338 <p>This action is rarely needed, as modern web browsers don't send <span class="QUOTE">"From:"</span>
2339 headers anymore.</p>
2341 <dt>Example usage:</dt>
2343 <table border="0" bgcolor="#E0E0E0" width="90%">
2346 <pre class="SCREEN">+hide-from-header{block}</pre>
2351 <table border="0" bgcolor="#E0E0E0" width="90%">
2354 <pre class="SCREEN">+hide-from-header{spam-me-senseless@sittingduck.example.com}</pre>
2363 <h4 class="SECT3"><a name="HIDE-REFERRER" id="HIDE-REFERRER">8.5.26. hide-referrer</a></h4><a name=
2364 "HIDE-REFERER" id="HIDE-REFERER"></a>
2365 <div class="VARIABLELIST">
2367 <dt>Typical use:</dt>
2369 <p>Conceal which link you followed to get to a particular site</p>
2373 <p>Deletes the <span class="QUOTE">"Referer:"</span> (sic) HTTP header from the client request, or
2374 replaces it with a forged one.</p>
2378 <p>Parameterized.</p>
2384 <p><span class="QUOTE">"conditional-block"</span> to delete the header completely if the host has
2388 <p><span class="QUOTE">"conditional-forge"</span> to forge the header if the host has changed.</p>
2391 <p><span class="QUOTE">"block"</span> to delete the header unconditionally.</p>
2394 <p><span class="QUOTE">"forge"</span> to pretend to be coming from the homepage of the server we are
2398 <p>Any other string to set a user defined referrer.</p>
2404 <p><tt class="LITERAL">conditional-block</tt> is the only parameter, that isn't easily detected in the
2405 server's log file. If it blocks the referrer, the request will look like the visitor used a bookmark or
2406 typed in the address directly.</p>
2407 <p>Leaving the referrer unmodified for requests on the same host allows the server owner to see the
2408 visitor's <span class="QUOTE">"click path"</span>, but in most cases she could also get that information
2409 by comparing other parts of the log file: for example the User-Agent if it isn't a very common one, or
2410 the user's IP address if it doesn't change between different requests.</p>
2411 <p>Always blocking the referrer, or using a custom one, can lead to failures on servers that check the
2412 referrer before they answer any requests, in an attempt to prevent their content from being embedded or
2413 linked to elsewhere.</p>
2414 <p>Both <tt class="LITERAL">conditional-block</tt> and <tt class="LITERAL">forge</tt> will work with
2415 referrer checks, as long as content and valid referring page are on the same host. Most of the time
2416 that's the case.</p>
2417 <p><tt class="LITERAL">hide-referer</tt> is an alternate spelling of <tt class=
2418 "LITERAL">hide-referrer</tt> and the two can be can be freely substituted with each other. (<span class=
2419 "QUOTE">"referrer"</span> is the correct English spelling, however the HTTP specification has a bug - it
2420 requires it to be spelled as <span class="QUOTE">"referer"</span>.)</p>
2422 <dt>Example usage:</dt>
2424 <table border="0" bgcolor="#E0E0E0" width="90%">
2427 <pre class="SCREEN">+hide-referrer{forge}</pre>
2432 <table border="0" bgcolor="#E0E0E0" width="90%">
2435 <pre class="SCREEN">+hide-referrer{http://www.yahoo.com/}</pre>
2444 <h4 class="SECT3"><a name="HIDE-USER-AGENT" id="HIDE-USER-AGENT">8.5.27. hide-user-agent</a></h4>
2445 <div class="VARIABLELIST">
2447 <dt>Typical use:</dt>
2449 <p>Try to conceal your type of browser and client operating system</p>
2453 <p>Replaces the value of the <span class="QUOTE">"User-Agent:"</span> HTTP header in client requests with
2454 the specified value.</p>
2458 <p>Parameterized.</p>
2462 <p>Any user-defined string.</p>
2466 <div class="WARNING">
2467 <table class="WARNING" border="1" width="90%">
2469 <td align="center"><b>Warning</b></td>
2473 <p>This can lead to problems on web sites that depend on looking at this header in order to
2474 customize their content for different browsers (which, by the way, is <span class=
2475 "emphasis"><i class="EMPHASIS">NOT</i></span> the right thing to do: good web sites work
2476 browser-independently).</p>
2481 <p>Using this action in multi-user setups or wherever different types of browsers will access the same
2482 <span class="APPLICATION">Privoxy</span> is <span class="emphasis"><i class="EMPHASIS">not
2483 recommended</i></span>. In single-user, single-browser setups, you might use it to delete your OS version
2484 information from the headers, because it is an invitation to exploit known bugs for your OS. It is also
2485 occasionally useful to forge this in order to access sites that won't let you in otherwise (though there
2486 may be a good reason in some cases).</p>
2487 <p>More information on known user-agent strings can be found at <a href="http://www.user-agents.org/"
2488 target="_top">http://www.user-agents.org/</a> and <a href="https://en.wikipedia.org/wiki/User_agent"
2489 target="_top">http://en.wikipedia.org/wiki/User_agent</a>.</p>
2491 <dt>Example usage:</dt>
2493 <table border="0" bgcolor="#E0E0E0" width="90%">
2497 "SCREEN">+hide-user-agent{Mozilla/5.0 (X11; ElectroBSD i386; rv:78.0) Gecko/20100101 Firefox/78.0}</pre>
2506 <h4 class="SECT3"><a name="HTTPS-INSPECTION" id="HTTPS-INSPECTION">8.5.28. https-inspection</a></h4>
2507 <div class="VARIABLELIST">
2509 <dt>Typical use:</dt>
2511 <p>Filter encrypted requests and responses</p>
2515 <p>Encrypted requests are decrypted, filtered and forwarded encrypted.</p>
2527 <p>This action allows <span class="APPLICATION">Privoxy</span> to filter encrypted requests and
2528 responses. For this to work <span class="APPLICATION">Privoxy</span> has to generate a certificate and
2529 send it to the client which has to accept it.</p>
2530 <p>Before this works the directives in the <tt class="LITERAL"><a href=
2531 "config.html#HTTPS-INSPECTION-DIRECTIVES" target="_top">HTTPS inspection section</a></tt> of the config
2532 file have to be configured.</p>
2533 <p>Note that the action has to be enabled based on the CONNECT request which doesn't contain a path.
2534 Enabling it based on a pattern with path doesn't work as the path is only seen by <span class=
2535 "APPLICATION">Privoxy</span> if the action is already enabled.</p>
2536 <p>This is an experimental feature.</p>
2538 <dt>Example usage (section):</dt>
2540 <table border="0" bgcolor="#E0E0E0" width="90%">
2543 <pre class="SCREEN">{+https-inspection}
2544 www.example.com</pre>
2553 <h4 class="SECT3"><a name="IGNORE-CERTIFICATE-ERRORS" id="IGNORE-CERTIFICATE-ERRORS">8.5.29.
2554 ignore-certificate-errors</a></h4>
2555 <div class="VARIABLELIST">
2557 <dt>Typical use:</dt>
2559 <p>Filter encrypted requests and responses without verifying the certificate</p>
2563 <p>Encrypted requests are forwarded to sites without verifying the certificate.</p>
2575 <p>When the <a href="actions-file.html#HTTPS-INSPECTION"><span class=
2576 "QUOTE">"+https-inspection"</span></a> action is used <span class="APPLICATION">Privoxy</span> by default
2577 verifies that the remote site uses a valid certificate.</p>
2578 <p>If the certificate can't be validated by <span class="APPLICATION">Privoxy</span> the connection is
2580 <p>This action disables the certificate check so requests to sites with certificates that can't be
2581 validated are allowed.</p>
2582 <p>Note that enabling this action allows Man-in-the-middle attacks.</p>
2584 <dt>Example usage:</dt>
2586 <table border="0" bgcolor="#E0E0E0" width="90%">
2589 <pre class="SCREEN"> {+ignore-certificate-errors}
2600 <h4 class="SECT3"><a name="LIMIT-CONNECT" id="LIMIT-CONNECT">8.5.30. limit-connect</a></h4>
2601 <div class="VARIABLELIST">
2603 <dt>Typical use:</dt>
2605 <p>Prevent abuse of <span class="APPLICATION">Privoxy</span> as a TCP proxy relay or disable SSL for
2610 <p>Specifies to which ports HTTP CONNECT requests are allowable.</p>
2614 <p>Parameterized.</p>
2618 <p>A comma-separated list of ports or port ranges (the latter using dashes, with the minimum defaulting
2619 to 0 and the maximum to 65K).</p>
2623 <p>By default, i.e. if no <tt class="LITERAL">limit-connect</tt> action applies, <span class=
2624 "APPLICATION">Privoxy</span> allows HTTP CONNECT requests to all ports. Use <tt class=
2625 "LITERAL">limit-connect</tt> if fine-grained control is desired for some or all destinations.</p>
2626 <p>The CONNECT methods exists in HTTP to allow access to secure websites (<span class=
2627 "QUOTE">"https://"</span> URLs) through proxies. It works very simply: the proxy connects to the server
2628 on the specified port, and then short-circuits its connections to the client and to the remote server.
2629 This means CONNECT-enabled proxies can be used as TCP relays very easily.</p>
2630 <p><span class="APPLICATION">Privoxy</span> relays HTTPS traffic without seeing the decoded content.
2631 Websites can leverage this limitation to circumvent <span class="APPLICATION">Privoxy</span>'s filters.
2632 By specifying an invalid port range you can disable HTTPS entirely.</p>
2634 <dt>Example usages:</dt>
2636 <table border="0" bgcolor="#E0E0E0" width="90%">
2639 <pre class="SCREEN">+limit-connect{443} # Port 443 is OK.
2640 +limit-connect{80,443} # Ports 80 and 443 are OK.
2641 +limit-connect{-3, 7, 20-100, 500-} # Ports less than 3, 7, 20 to 100 and above 500 are OK.
2642 +limit-connect{-} # All ports are OK
2643 +limit-connect{,} # No HTTPS/SSL traffic is allowed</pre>
2652 <h4 class="SECT3"><a name="LIMIT-COOKIE-LIFETIME" id="LIMIT-COOKIE-LIFETIME">8.5.31.
2653 limit-cookie-lifetime</a></h4>
2654 <div class="VARIABLELIST">
2656 <dt>Typical use:</dt>
2658 <p>Limit the lifetime of HTTP cookies to a couple of minutes or hours.</p>
2662 <p>Overwrites the expires field in Set-Cookie server headers if it's above the specified limit.</p>
2666 <p>Parameterized.</p>
2670 <p>The lifetime limit in minutes, or 0.</p>
2674 <p>This action reduces the lifetime of HTTP cookies coming from the server to the specified number of
2675 minutes, starting from the time the cookie passes Privoxy.</p>
2676 <p>Cookies with a lifetime below the limit are not modified. The lifetime of session cookies is set to
2677 the specified limit.</p>
2678 <p>The effect of this action depends on the server.</p>
2679 <p>In case of servers which refresh their cookies with each response (or at least frequently), the
2680 lifetime limit set by this action is updated as well. Thus, a session associated with the cookie
2681 continues to work with this action enabled, as long as a new request is made before the last limit set is
2683 <p>However, some servers send their cookies once, with a lifetime of several years (the year 2037 is a
2684 popular choice), and do not refresh them until a certain event in the future, for example the user
2685 logging out. In this case this action may limit the absolute lifetime of the session, even if requests
2686 are made frequently.</p>
2687 <p>If the parameter is <span class="QUOTE">"0"</span>, this action behaves like <tt class=
2688 "LITERAL"><a href="actions-file.html#SESSION-COOKIES-ONLY">session-cookies-only</a></tt>.</p>
2690 <dt>Example usages:</dt>
2692 <table border="0" bgcolor="#E0E0E0" width="90%">
2695 <pre class="SCREEN">+limit-cookie-lifetime{60}</pre>
2704 <h4 class="SECT3"><a name="PREVENT-COMPRESSION" id="PREVENT-COMPRESSION">8.5.32. prevent-compression</a></h4>
2705 <div class="VARIABLELIST">
2707 <dt>Typical use:</dt>
2709 <p>Ensure that servers send the content uncompressed, so it can be passed through <tt class=
2710 "LITERAL"><a href="actions-file.html#FILTER">filter</a></tt>s.</p>
2714 <p>Removes the Accept-Encoding header which can be used to ask for compressed transfer.</p>
2726 <p>More and more websites send their content compressed by default, which is generally a good idea and
2727 saves bandwidth. But the <tt class="LITERAL"><a href="actions-file.html#FILTER">filter</a></tt> and
2728 <tt class="LITERAL"><a href="actions-file.html#DEANIMATE-GIFS">deanimate-gifs</a></tt> actions need
2729 access to the uncompressed data.</p>
2730 <p>When compiled with zlib support (available since <span class="APPLICATION">Privoxy</span> 3.0.7),
2731 content that should be filtered is decompressed on-the-fly and you don't have to worry about this action.
2732 If you are using an older <span class="APPLICATION">Privoxy</span> version, or one that hasn't been
2733 compiled with zlib support, this action can be used to convince the server to send the content
2735 <p>Most text-based instances compress very well, the size is seldom decreased by less than 50%, for
2736 markup-heavy instances like news feeds saving more than 90% of the original size isn't unusual.</p>
2737 <p>Not using compression will therefore slow down the transfer, and you should only enable this action if
2738 you really need it. As of <span class="APPLICATION">Privoxy</span> 3.0.7 it's disabled in all predefined
2739 action settings.</p>
2740 <p>Note that some (rare) ill-configured sites don't handle requests for uncompressed documents correctly.
2741 Broken PHP applications tend to send an empty document body, some IIS versions only send the beginning of
2742 the content and some content delivery networks let the connection time out. If you enable <tt class=
2743 "LITERAL">prevent-compression</tt> per default, you might want to add exceptions for those sites. See the
2744 example for how to do that.</p>
2746 <dt>Example usage (sections):</dt>
2748 <table border="0" bgcolor="#E0E0E0" width="90%">
2751 <pre class="SCREEN"># Selectively turn off compression, and enable a filter
2753 { +filter{tiny-textforms} +prevent-compression }
2754 # Match only these sites
2759 # Or instead, we could set a universal default:
2761 { +prevent-compression }
2764 # Then maybe make exceptions for broken sites:
2766 { -prevent-compression }
2776 <h4 class="SECT3"><a name="OVERWRITE-LAST-MODIFIED" id="OVERWRITE-LAST-MODIFIED">8.5.33.
2777 overwrite-last-modified</a></h4>
2778 <div class="VARIABLELIST">
2780 <dt>Typical use:</dt>
2782 <p>Prevent yet another way to track the user's steps between sessions.</p>
2786 <p>Deletes the <span class="QUOTE">"Last-Modified:"</span> HTTP server header or modifies its value.</p>
2790 <p>Parameterized.</p>
2794 <p>One of the keywords: <span class="QUOTE">"block"</span>, <span class=
2795 "QUOTE">"reset-to-request-time"</span> and <span class="QUOTE">"randomize"</span></p>
2799 <p>Removing the <span class="QUOTE">"Last-Modified:"</span> header is useful for filter testing, where
2800 you want to force a real reload instead of getting status code <span class="QUOTE">"304"</span>, which
2801 would cause the browser to reuse the old version of the page.</p>
2802 <p>The <span class="QUOTE">"randomize"</span> option overwrites the value of the <span class=
2803 "QUOTE">"Last-Modified:"</span> header with a randomly chosen time between the original value and the
2804 current time. In theory the server could send each document with a different <span class=
2805 "QUOTE">"Last-Modified:"</span> header to track visits without using cookies. <span class=
2806 "QUOTE">"Randomize"</span> makes it impossible and the browser can still revalidate cached documents.</p>
2807 <p><span class="QUOTE">"reset-to-request-time"</span> overwrites the value of the <span class=
2808 "QUOTE">"Last-Modified:"</span> header with the current time. You could use this option together with
2809 <tt class="LITERAL"><a href="actions-file.html#HIDE-IF-MODIFIED-SINCE">hide-if-modified-since</a></tt> to
2810 further customize your random range.</p>
2811 <p>The preferred parameter here is <span class="QUOTE">"randomize"</span>. It is safe to use, as long as
2812 the time settings are more or less correct. If the server sets the <span class=
2813 "QUOTE">"Last-Modified:"</span> header to the time of the request, the random range becomes zero and the
2814 value stays the same. Therefore you should later randomize it a second time with <tt class=
2815 "LITERAL"><a href="actions-file.html#HIDE-IF-MODIFIED-SINCE">hided-if-modified-since</a></tt>, just to be
2817 <p>It is also recommended to use this action together with <tt class="LITERAL"><a href=
2818 "actions-file.html#CRUNCH-IF-NONE-MATCH">crunch-if-none-match</a></tt>.</p>
2820 <dt>Example usage:</dt>
2822 <table border="0" bgcolor="#E0E0E0" width="90%">
2825 <pre class="SCREEN"># Let the browser revalidate without being tracked across sessions
2826 { +hide-if-modified-since{-60} \
2827 +overwrite-last-modified{randomize} \
2828 +crunch-if-none-match}
2838 <h4 class="SECT3"><a name="REDIRECT" id="REDIRECT">8.5.34. redirect</a></h4>
2839 <div class="VARIABLELIST">
2841 <dt>Typical use:</dt>
2843 <p>Redirect requests to other sites.</p>
2847 <p>Convinces the browser that the requested document has been moved to another location and the browser
2848 should get it from there.</p>
2852 <p>Parameterized</p>
2856 <p>An absolute URL or a single pcrs command.</p>
2860 <p>Requests to which this action applies are answered with a HTTP redirect to URLs of your choosing. The
2861 new URL is either provided as parameter, or derived by applying a single pcrs command to the original
2863 <p>The syntax for pcrs commands is documented in the <a href="filter-file.html">filter file</a>
2865 <p>Requests can't be blocked and redirected at the same time, applying this action together with
2866 <tt class="LITERAL"><a href="actions-file.html#BLOCK">block</a></tt> is a configuration error. Currently
2867 the request is blocked and an error message logged, the behavior may change in the future and result in
2868 Privoxy rejecting the action file.</p>
2869 <p>This action can be combined with <tt class="LITERAL"><a href=
2870 "actions-file.html#FAST-REDIRECTS">fast-redirects{check-decoded-url}</a></tt> to redirect to a decoded
2871 version of a rewritten URL.</p>
2872 <p>Use this action carefully, make sure not to create redirection loops and be aware that using your own
2873 redirects might make it possible to fingerprint your requests.</p>
2874 <p>In case of problems with your redirects, or simply to watch them working, enable <a href=
2875 "config.html#DEBUG">debug 128</a>.</p>
2877 <dt>Example usages:</dt>
2879 <table border="0" bgcolor="#E0E0E0" width="90%">
2882 <pre class="SCREEN"># Replace example.com's style sheet with another one
2883 { +redirect{http://localhost/css-replacements/example.com.css} }
2884 example.com/stylesheet\.css
2886 # Create a short, easy to remember nickname for a favorite site
2887 # (relies on the browser to accept and forward invalid URLs to <span class="APPLICATION">Privoxy</span>)
2888 { +redirect{https://www.privoxy.org/user-manual/actions-file.html} }
2891 # Always use the expanded view for Undeadly.org articles
2892 # (Note the $ at the end of the URL pattern to make sure
2893 # the request for the rewritten URL isn't redirected as well)
2894 {+redirect{s@$@&mode=expanded@}}
2895 undeadly.org/cgi\?action=article&sid=\d*$
2897 # Redirect Google search requests to MSN
2898 {+redirect{s@^http://[^/]*/search\?q=([^&]*).*@http://search.msn.com/results.aspx?q=$1@}}
2901 # Redirect MSN search requests to Yahoo
2902 {+redirect{s@^http://[^/]*/results\.aspx\?q=([^&]*).*@http://search.yahoo.com/search?p=$1@}}
2903 search.msn.com//results\.aspx\?q=
2905 # Redirect http://example.com/&bla=fasel&toChange=foo (and any other value but "bar")
2906 # to http://example.com/&bla=fasel&toChange=bar
2908 # The URL pattern makes sure that the following request isn't redirected again.
2909 {+redirect{s@toChange=[^&]+@toChange=bar@}}
2910 example.com/.*toChange=(?!bar)
2912 # Add a shortcut to look up illumos bugs
2913 {+redirect{s@^http://i([0-9]+)/.*@https://www.illumos.org/issues/$1@}}
2914 # Redirected URL = http://i4974/
2915 # Redirect Destination = https://www.illumos.org/issues/4974
2916 i[0-9][0-9][0-9][0-9]*/
2918 # Redirect requests for the old Tor Hidden Service of the Privoxy website to the new one
2919 {+redirect{s@^http://jvauzb4sb3bwlsnc.onion/@http://l3tczdiiwoo63iwxty4lhs6p7eaxop5micbn7vbliydgv63x5zrrrfyd.onion/@}}
2920 jvauzb4sb3bwlsnc.onion/
2922 # Redirect remote requests for this manual
2923 # to the local version delivered by Privoxy
2924 {+redirect{s@^http://www@http://config@}}
2925 www.privoxy.org/user-manual/</pre>
2934 <h4 class="SECT3"><a name="SERVER-HEADER-FILTER" id="SERVER-HEADER-FILTER">8.5.35.
2935 server-header-filter</a></h4>
2936 <div class="VARIABLELIST">
2938 <dt>Typical use:</dt>
2940 <p>Rewrite or remove single server headers.</p>
2944 <p>All server headers to which this action applies are filtered on-the-fly through the specified regular
2945 expression based substitutions.</p>
2953 <p>The name of a server-header filter, as defined in one of the <a href="filter-file.html">filter
2958 <p>Server-header filters are applied to each header on its own, not to all at once. This makes it easier
2959 to diagnose problems, but on the downside you can't write filters that only change header x if header y's
2960 value is z. You can do that by using tags though.</p>
2961 <p>Server-header filters are executed after the other header actions have finished and use their output
2963 <p>Please refer to the <a href="filter-file.html">filter file chapter</a> to learn which server-header
2964 filters are available by default, and how to create your own.</p>
2966 <dt>Example usage (section):</dt>
2968 <table border="0" bgcolor="#E0E0E0" width="90%">
2971 <pre class="SCREEN">{+server-header-filter{html-to-xml}}
2972 example.org/xml-instance-that-is-delivered-as-html
2974 {+server-header-filter{xml-to-html}}
2975 example.org/instance-that-is-delivered-as-xml-but-is-not</pre>
2984 <h4 class="SECT3"><a name="SERVER-HEADER-TAGGER" id="SERVER-HEADER-TAGGER">8.5.36.
2985 server-header-tagger</a></h4>
2986 <div class="VARIABLELIST">
2988 <dt>Typical use:</dt>
2990 <p>Enable or disable filters based on the Content-Type header.</p>
2994 <p>Server headers to which this action applies are filtered on-the-fly through the specified regular
2995 expression based substitutions, the result is used as tag.</p>
3003 <p>The name of a server-header tagger, as defined in one of the <a href="filter-file.html">filter
3008 <p>Server-header taggers are applied to each header on its own, and as the header isn't modified, each
3009 tagger <span class="QUOTE">"sees"</span> the original.</p>
3010 <p>Server-header taggers are executed before all other header actions that modify server headers. Their
3011 tags can be used to control all of the other server-header actions, the content filters and the crunch
3012 actions (<a href="actions-file.html#REDIRECT">redirect</a> and <a href=
3013 "actions-file.html#BLOCK">block</a>).</p>
3014 <p>Obviously crunching based on tags created by server-header taggers doesn't prevent the request from
3015 showing up in the server's log file.</p>
3017 <dt>Example usage (section):</dt>
3019 <table border="0" bgcolor="#E0E0E0" width="90%">
3022 <pre class="SCREEN"># Tag every request with the content type declared by the server
3023 {+server-header-tagger{content-type}}
3026 # If the response has a tag starting with 'image/' enable an external
3027 # filter that only applies to images.
3029 # Note that the filter is not available by default, it's just a
3030 # <tt class="LITERAL"><a href="filter-file.html#EXTERNAL-FILTER-SYNTAX">silly example</a></tt>.
3031 {+external-filter{rotate-image} +force-text-mode}
3041 <h4 class="SECT3"><a name="SUPPRESS-TAG" id="SUPPRESS-TAG">8.5.37. suppress-tag</a></h4>
3042 <div class="VARIABLELIST">
3044 <dt>Typical use:</dt>
3046 <p>Suppress client or server tag.</p>
3050 <p>Server or client tags to which this action applies are not added to the request, thus making all
3051 actions that are specific to these request tags inactive.</p>
3059 <p>The result tag of a server-header or client-header tagger, as defined in one of the <a href=
3060 "filter-file.html">filter files</a>.</p>
3062 <dt>Example usage (section):</dt>
3064 <table border="0" bgcolor="#E0E0E0" width="90%">
3068 "SCREEN"># Suppress tag produced by range-requests client-header tagger for requests coming from address 10.0.0.1
3069 {+suppress-tag{RANGE-REQUEST}}
3070 TAG:^IP-ADDRESS: 10\.0\.0\.1$</pre>
3079 <h4 class="SECT3"><a name="SESSION-COOKIES-ONLY" id="SESSION-COOKIES-ONLY">8.5.38.
3080 session-cookies-only</a></h4>
3081 <div class="VARIABLELIST">
3083 <dt>Typical use:</dt>
3085 <p>Allow only temporary <span class="QUOTE">"session"</span> cookies (for the current browser session
3086 <span class="emphasis"><i class="EMPHASIS">only</i></span>).</p>
3090 <p>Deletes the <span class="QUOTE">"expires"</span> field from <span class="QUOTE">"Set-Cookie:"</span>
3091 server headers. Most browsers will not store such cookies permanently and forget them in between
3104 <p>This is less strict than <tt class="LITERAL"><a href=
3105 "actions-file.html#CRUNCH-INCOMING-COOKIES">crunch-incoming-cookies</a></tt> / <tt class=
3106 "LITERAL"><a href="actions-file.html#CRUNCH-OUTGOING-COOKIES">crunch-outgoing-cookies</a></tt> and allows
3107 you to browse websites that insist or rely on setting cookies, without compromising your privacy too
3109 <p>Most browsers will not permanently store cookies that have been processed by <tt class=
3110 "LITERAL">session-cookies-only</tt> and will forget about them between sessions. This makes profiling
3111 cookies useless, but won't break sites which require cookies so that you can log in for transactions.
3112 This is generally turned on for all sites, and is the recommended setting.</p>
3113 <p>It makes <span class="emphasis"><i class="EMPHASIS">no sense at all</i></span> to use <tt class=
3114 "LITERAL">session-cookies-only</tt> together with <tt class="LITERAL"><a href=
3115 "actions-file.html#CRUNCH-INCOMING-COOKIES">crunch-incoming-cookies</a></tt> or <tt class=
3116 "LITERAL"><a href="actions-file.html#CRUNCH-OUTGOING-COOKIES">crunch-outgoing-cookies</a></tt>. If you
3117 do, cookies will be plainly killed.</p>
3118 <p>Note that it is up to the browser how it handles such cookies without an <span class=
3119 "QUOTE">"expires"</span> field. If you use an exotic browser, you might want to try it out to be
3121 <p>This setting also has no effect on cookies that may have been stored previously by the browser before
3122 starting <span class="APPLICATION">Privoxy</span>. These would have to be removed manually.</p>
3123 <p><span class="APPLICATION">Privoxy</span> also uses the <a href=
3124 "actions-file.html#FILTER-CONTENT-COOKIES">content-cookies filter</a> to block some types of cookies.
3125 Content cookies are not effected by <tt class="LITERAL">session-cookies-only</tt>.</p>
3127 <dt>Example usage:</dt>
3129 <table border="0" bgcolor="#E0E0E0" width="90%">
3132 <pre class="SCREEN">+session-cookies-only</pre>
3141 <h4 class="SECT3"><a name="SET-IMAGE-BLOCKER" id="SET-IMAGE-BLOCKER">8.5.39. set-image-blocker</a></h4>
3142 <div class="VARIABLELIST">
3144 <dt>Typical use:</dt>
3146 <p>Choose the replacement for blocked images</p>
3150 <p>This action alone doesn't do anything noticeable. If <span class="emphasis"><i class=
3151 "EMPHASIS">both</i></span> <tt class="LITERAL"><a href="actions-file.html#BLOCK">block</a></tt>
3152 <span class="emphasis"><i class="EMPHASIS">and</i></span> <tt class="LITERAL"><a href=
3153 "actions-file.html#HANDLE-AS-IMAGE">handle-as-image</a></tt> <span class="emphasis"><i class=
3154 "EMPHASIS">also</i></span> apply, i.e. if the request is to be blocked as an image, <span class=
3155 "emphasis"><i class="EMPHASIS">then</i></span> the parameter of this action decides what will be sent as
3160 <p>Parameterized.</p>
3166 <p><span class="QUOTE">"pattern"</span> to send a built-in checkerboard pattern image. The image is
3167 visually decent, scales very well, and makes it obvious where banners were busted.</p>
3170 <p><span class="QUOTE">"blank"</span> to send a built-in transparent image. This makes banners
3171 disappear completely, but makes it hard to detect where <span class="APPLICATION">Privoxy</span> has
3172 blocked images on a given page and complicates troubleshooting if <span class=
3173 "APPLICATION">Privoxy</span> has blocked innocent images, like navigation icons.</p>
3176 <p><span class="QUOTE">"<tt class="REPLACEABLE"><i>target-url</i></tt>"</span> to send a redirect to
3177 <tt class="REPLACEABLE"><i>target-url</i></tt>. You can redirect to any image anywhere, even in your
3178 local filesystem via <span class="QUOTE">"file:///"</span> URL. (But note that not all browsers
3179 support redirecting to a local file system).</p>
3180 <p>A good application of redirects is to use special <span class=
3181 "APPLICATION">Privoxy</span>-built-in URLs, which send the built-in images, as <tt class=
3182 "REPLACEABLE"><i>target-url</i></tt>. This has the same visual effect as specifying <span class=
3183 "QUOTE">"blank"</span> or <span class="QUOTE">"pattern"</span> in the first place, but enables your
3184 browser to cache the replacement image, instead of requesting it over and over again.</p>
3190 <p>The URLs for the built-in images are <span class=
3191 "QUOTE">"http://config.privoxy.org/send-banner?type=<tt class="REPLACEABLE"><i>type</i></tt>"</span>,
3192 where <tt class="REPLACEABLE"><i>type</i></tt> is either <span class="QUOTE">"blank"</span> or
3193 <span class="QUOTE">"pattern"</span>.</p>
3194 <p>There is a third (advanced) type, called <span class="QUOTE">"auto"</span>. It is <span class=
3195 "emphasis"><i class="EMPHASIS">NOT</i></span> to be used in <tt class="LITERAL">set-image-blocker</tt>,
3196 but meant for use from <a href="filter-file.html">filters</a>. Auto will select the type of image that
3197 would have applied to the referring page, had it been an image.</p>
3199 <dt>Example usage:</dt>
3201 <p>Built-in pattern:</p>
3202 <table border="0" bgcolor="#E0E0E0" width="90%">
3205 <pre class="SCREEN">+set-image-blocker{pattern}</pre>
3209 <p>Redirect to the BSD daemon:</p>
3210 <table border="0" bgcolor="#E0E0E0" width="90%">
3213 <pre class="SCREEN">+set-image-blocker{http://www.freebsd.org/gifs/dae_up3.gif}</pre>
3217 <p>Redirect to the built-in pattern for better caching:</p>
3218 <table border="0" bgcolor="#E0E0E0" width="90%">
3221 <pre class="SCREEN">+set-image-blocker{http://config.privoxy.org/send-banner?type=pattern}</pre>
3230 <h3 class="SECT3"><a name="SUMMARY" id="SUMMARY">8.5.40. Summary</a></h3>
3231 <p>Note that many of these actions have the potential to cause a page to misbehave, possibly even not to
3232 display at all. There are many ways a site designer may choose to design his site, and what HTTP header
3233 content, and other criteria, he may depend on. There is no way to have hard and fast rules for all sites. See
3234 the <a href="appendix.html#ACTIONSANAT">Appendix</a> for a brief example on troubleshooting actions.</p>
3238 <h2 class="SECT2"><a name="ALIASES" id="ALIASES">8.6. Aliases</a></h2>
3239 <p>Custom <span class="QUOTE">"actions"</span>, known to <span class="APPLICATION">Privoxy</span> as <span class=
3240 "QUOTE">"aliases"</span>, can be defined by combining other actions. These can in turn be invoked just like the
3241 built-in actions. Currently, an alias name can contain any character except space, tab, <span class=
3242 "QUOTE">"="</span>, <span class="QUOTE">"{"</span> and <span class="QUOTE">"}"</span>, but we <span class=
3243 "emphasis"><i class="EMPHASIS">strongly recommend</i></span> that you only use <span class="QUOTE">"a"</span> to
3244 <span class="QUOTE">"z"</span>, <span class="QUOTE">"0"</span> to <span class="QUOTE">"9"</span>, <span class=
3245 "QUOTE">"+"</span>, and <span class="QUOTE">"-"</span>. Alias names are not case sensitive, and are not required
3246 to start with a <span class="QUOTE">"+"</span> or <span class="QUOTE">"-"</span> sign, since they are merely
3247 textually expanded.</p>
3248 <p>Aliases can be used throughout the actions file, but they <span class="emphasis"><i class="EMPHASIS">must be
3249 defined in a special section at the top of the file!</i></span> And there can only be one such section per
3250 actions file. Each actions file may have its own alias section, and the aliases defined in it are only visible
3251 within that file.</p>
3252 <p>There are two main reasons to use aliases: One is to save typing for frequently used combinations of actions,
3253 the other one is a gain in flexibility: If you decide once how you want to handle shops by defining an alias
3254 called <span class="QUOTE">"shop"</span>, you can later change your policy on shops in <span class=
3255 "emphasis"><i class="EMPHASIS">one</i></span> place, and your changes will take effect everywhere in the actions
3256 file where the <span class="QUOTE">"shop"</span> alias is used. Calling aliases by their purpose also makes your
3257 actions files more readable.</p>
3258 <p>Currently, there is one big drawback to using aliases, though: <span class="APPLICATION">Privoxy</span>'s
3259 built-in web-based action file editor honors aliases when reading the actions files, but it expands them before
3260 writing. So the effects of your aliases are of course preserved, but the aliases themselves are lost when you
3261 edit sections that use aliases with it.</p>
3262 <p>Now let's define some aliases...</p>
3263 <table border="0" bgcolor="#E0E0E0" width="100%">
3266 <pre class="SCREEN"> # Useful custom aliases we can use later.
3268 # Note the (required!) section header line and that this section
3269 # must be at the top of the actions file!
3273 # These aliases just save typing later:
3274 # (Note that some already use other aliases!)
3276 +crunch-all-cookies = +<a href="actions-file.html#CRUNCH-INCOMING-COOKIES">crunch-incoming-cookies</a> +<a href=
3277 "actions-file.html#CRUNCH-OUTGOING-COOKIES">crunch-outgoing-cookies</a>
3278 -crunch-all-cookies = -<a href="actions-file.html#CRUNCH-INCOMING-COOKIES">crunch-incoming-cookies</a> -<a href=
3279 "actions-file.html#CRUNCH-OUTGOING-COOKIES">crunch-outgoing-cookies</a>
3280 +block-as-image = +block{Blocked image.} +handle-as-image
3281 allow-all-cookies = -crunch-all-cookies -<a href=
3282 "actions-file.html#SESSION-COOKIES-ONLY">session-cookies-only</a> -<a href=
3283 "actions-file.html#FILTER-CONTENT-COOKIES">filter{content-cookies}</a>
3285 # These aliases define combinations of actions
3286 # that are useful for certain types of sites:
3288 fragile = -<a href="actions-file.html#BLOCK">block</a> -<a href=
3289 "actions-file.html#FILTER">filter</a> -crunch-all-cookies -<a href=
3290 "actions-file.html#FAST-REDIRECTS">fast-redirects</a> -<a href=
3291 "actions-file.html#HIDE-REFERER">hide-referrer</a> -<a href=
3292 "actions-file.html#PREVENT-COMPRESSION">prevent-compression</a>
3294 shop = -crunch-all-cookies -<a href="actions-file.html#FILTER-ALL-POPUPS">filter{all-popups}</a>
3296 # Short names for other aliases, for really lazy people ;-)
3298 c0 = +crunch-all-cookies
3299 c1 = -crunch-all-cookies</pre>
3303 <p>...and put them to use. These sections would appear in the lower part of an actions file and define exceptions
3304 to the default actions (as specified further up for the <span class="QUOTE">"/"</span> pattern):</p>
3305 <table border="0" bgcolor="#E0E0E0" width="100%">
3308 <pre class="SCREEN"> # These sites are either very complex or very keen on
3309 # user data and require minimal interference to work:
3312 .office.microsoft.com
3313 .windowsupdate.microsoft.com
3314 # Gmail is really mail.google.com, not gmail.com
3318 # Allow cookies (for setting and retrieving your customer data)
3322 .worldpay.com # for quietpc.com
3325 # These shops require pop-ups:
3327 {-filter{all-popups} -filter{unsolicited-popups}}
3329 .overclockers.co.uk</pre>
3333 <p>Aliases like <span class="QUOTE">"shop"</span> and <span class="QUOTE">"fragile"</span> are typically used for
3334 <span class="QUOTE">"problem"</span> sites that require more than one action to be disabled in order to function
3338 <h2 class="SECT2"><a name="ACT-EXAMPLES" id="ACT-EXAMPLES">8.7. Actions Files Tutorial</a></h2>
3339 <p>The above chapters have shown <a href="actions-file.html">which actions files there are and how they are
3340 organized</a>, how actions are <a href="actions-file.html#ACTIONS">specified</a> and <a href=
3341 "actions-file.html#ACTIONS-APPLY">applied to URLs</a>, how <a href="actions-file.html#AF-PATTERNS">patterns</a>
3342 work, and how to define and use <a href="actions-file.html#ALIASES">aliases</a>. Now, let's look at an example
3343 <tt class="FILENAME">match-all.action</tt>, <tt class="FILENAME">default.action</tt> and <tt class=
3344 "FILENAME">user.action</tt> file and see how all these pieces come together:</p>
3346 <h3 class="SECT3"><a name="MATCH-ALL" id="MATCH-ALL">8.7.1. match-all.action</a></h3>
3347 <p>Remember <span class="emphasis"><i class="EMPHASIS">all actions are disabled when matching
3348 starts</i></span>, so we have to explicitly enable the ones we want.</p>
3349 <p>While the <tt class="FILENAME">match-all.action</tt> file only contains a single section, it is probably the
3350 most important one. It has only one pattern, <span class="QUOTE">"<tt class="LITERAL">/</tt>"</span>, but this
3351 pattern <a href="actions-file.html#AF-PATTERNS">matches all URLs</a>. Therefore, the set of actions used in
3352 this <span class="QUOTE">"default"</span> section <span class="emphasis"><i class="EMPHASIS">will be applied to
3353 all requests as a start</i></span>. It can be partly or wholly overridden by other actions files like
3354 <tt class="FILENAME">default.action</tt> and <tt class="FILENAME">user.action</tt>, but it will still be
3355 largely responsible for your overall browsing experience.</p>
3356 <p>Again, at the start of matching, all actions are disabled, so there is no need to disable any actions here.
3357 (Remember: a <span class="QUOTE">"+"</span> preceding the action name enables the action, a <span class=
3358 "QUOTE">"-"</span> disables!). Also note how this long line has been made more readable by splitting it into
3359 multiple lines with line continuation.</p>
3360 <table border="0" bgcolor="#E0E0E0" width="100%">
3363 <pre class="SCREEN">{ \
3364 +<a href="actions-file.html#CHANGE-X-FORWARDED-FOR">change-x-forwarded-for{block}</a> \
3365 +<a href="actions-file.html#HIDE-FROM-HEADER">hide-from-header{block}</a> \
3366 +<a href="actions-file.html#SET-IMAGE-BLOCKER">set-image-blocker{pattern}</a> \
3368 / # Match all URLs</pre>
3372 <p>The default behavior is now set.</p>
3375 <h3 class="SECT3"><a name="DEFAULT-ACTION" id="DEFAULT-ACTION">8.7.2. default.action</a></h3>
3376 <p>If you aren't a developer, there's no need for you to edit the <tt class="FILENAME">default.action</tt>
3377 file. It is maintained by the <span class="APPLICATION">Privoxy</span> developers and if you disagree with some
3378 of the sections, you should overrule them in your <tt class="FILENAME">user.action</tt>.</p>
3379 <p>Understanding the <tt class="FILENAME">default.action</tt> file can help you with your <tt class=
3380 "FILENAME">user.action</tt>, though.</p>
3381 <p>The first section in this file is a special section for internal use that prevents older <span class=
3382 "APPLICATION">Privoxy</span> versions from reading the file:</p>
3383 <table border="0" bgcolor="#E0E0E0" width="100%">
3386 <pre class="SCREEN">##########################################################################
3387 # Settings -- Don't change! For internal Privoxy use ONLY.
3388 ##########################################################################
3390 for-privoxy-version=3.0.11</pre>
3394 <p>After that comes the (optional) alias section. We'll use the example section from the above <a href=
3395 "actions-file.html#ALIASES">chapter on aliases</a>, that also explains why and how aliases are used:</p>
3396 <table border="0" bgcolor="#E0E0E0" width="100%">
3399 <pre class="SCREEN">##########################################################################
3401 ##########################################################################
3404 # These aliases just save typing later:
3405 # (Note that some already use other aliases!)
3407 +crunch-all-cookies = +<a href="actions-file.html#CRUNCH-INCOMING-COOKIES">crunch-incoming-cookies</a> +<a href=
3408 "actions-file.html#CRUNCH-OUTGOING-COOKIES">crunch-outgoing-cookies</a>
3409 -crunch-all-cookies = -<a href="actions-file.html#CRUNCH-INCOMING-COOKIES">crunch-incoming-cookies</a> -<a href=
3410 "actions-file.html#CRUNCH-OUTGOING-COOKIES">crunch-outgoing-cookies</a>
3411 +block-as-image = +block{Blocked image.} +handle-as-image
3412 mercy-for-cookies = -crunch-all-cookies -<a href=
3413 "actions-file.html#SESSION-COOKIES-ONLY">session-cookies-only</a> -<a href=
3414 "actions-file.html#FILTER-CONTENT-COOKIES">filter{content-cookies}</a>
3416 # These aliases define combinations of actions
3417 # that are useful for certain types of sites:
3419 fragile = -<a href="actions-file.html#BLOCK">block</a> -<a href=
3420 "actions-file.html#FILTER">filter</a> -crunch-all-cookies -<a href=
3421 "actions-file.html#FAST-REDIRECTS">fast-redirects</a> -<a href="actions-file.html#HIDE-REFERER">hide-referrer</a>
3422 shop = -crunch-all-cookies -<a href="actions-file.html#FILTER-ALL-POPUPS">filter{all-popups}</a></pre>
3426 <p>The first of our specialized sections is concerned with <span class="QUOTE">"fragile"</span> sites, i.e.
3427 sites that require minimum interference, because they are either very complex or very keen on tracking you (and
3428 have mechanisms in place that make them unusable for people who avoid being tracked). We will use our
3429 pre-defined <tt class="LITERAL">fragile</tt> alias instead of stating the list of actions explicitly:</p>
3430 <table border="0" bgcolor="#E0E0E0" width="100%">
3433 <pre class="SCREEN">##########################################################################
3434 # Exceptions for sites that'll break under the default action set:
3435 ##########################################################################
3437 # "Fragile" Use a minimum set of actions for these sites (see alias above):
3440 .office.microsoft.com # surprise, surprise!
3441 .windowsupdate.microsoft.com
3442 mail.google.com</pre>
3446 <p>Shopping sites are not as fragile, but they typically require cookies to log in, and pop-up windows for
3447 shopping carts or item details. Again, we'll use a pre-defined alias:</p>
3448 <table border="0" bgcolor="#E0E0E0" width="100%">
3451 <pre class="SCREEN"># Shopping sites:
3455 .worldpay.com # for quietpc.com
3461 <p>The <tt class="LITERAL"><a href="actions-file.html#FAST-REDIRECTS">fast-redirects</a></tt> action, which may
3462 have been enabled in <tt class="FILENAME">match-all.action</tt>, breaks some sites. So disable it for popular
3463 sites where we know it misbehaves:</p>
3464 <table border="0" bgcolor="#E0E0E0" width="100%">
3467 <pre class="SCREEN">{ -<a href="actions-file.html#FAST-REDIRECTS">fast-redirects</a> }
3471 .altavista.com/.*(like|url|link):http
3472 .altavista.com/trans.*urltext=http
3477 <p>It is important that <span class="APPLICATION">Privoxy</span> knows which URLs belong to images, so that
3478 <span class="emphasis"><i class="EMPHASIS">if</i></span> they are to be blocked, a substitute image can be
3479 sent, rather than an HTML page. Contacting the remote site to find out is not an option, since it would destroy
3480 the loading time advantage of banner blocking, and it would feed the advertisers information about you. We can
3481 mark any URL as an image with the <tt class="LITERAL"><a href=
3482 "actions-file.html#HANDLE-AS-IMAGE">handle-as-image</a></tt> action, and marking all URLs that end in a known
3483 image file extension is a good start:</p>
3484 <table border="0" bgcolor="#E0E0E0" width="100%">
3487 <pre class="SCREEN">##########################################################################
3489 ##########################################################################
3491 # Define which file types will be treated as images, in case they get
3492 # blocked further down this file:
3494 { +<a href="actions-file.html#HANDLE-AS-IMAGE">handle-as-image</a> }
3495 /.*\.(gif|jpe?g|png|bmp|ico)$</pre>
3499 <p>And then there are known banner sources. They often use scripts to generate the banners, so it won't be
3500 visible from the URL that the request is for an image. Hence we block them <span class="emphasis"><i class=
3501 "EMPHASIS">and</i></span> mark them as images in one go, with the help of our <tt class=
3502 "LITERAL">+block-as-image</tt> alias defined above. (We could of course just as well use <tt class=
3503 "LITERAL">+<a href="actions-file.html#BLOCK">block</a> +<a href=
3504 "actions-file.html#HANDLE-AS-IMAGE">handle-as-image</a></tt> here.) Remember that the type of the replacement
3505 image is chosen by the <tt class="LITERAL"><a href=
3506 "actions-file.html#SET-IMAGE-BLOCKER">set-image-blocker</a></tt> action. Since all URLs have matched the
3507 default section with its <tt class="LITERAL">+<a href=
3508 "actions-file.html#SET-IMAGE-BLOCKER">set-image-blocker</a>{pattern}</tt> action before, it still applies and
3509 needn't be repeated:</p>
3510 <table border="0" bgcolor="#E0E0E0" width="100%">
3513 <pre class="SCREEN"># Known ad generators:
3518 .ad.*.doubleclick.net
3519 .a.yimg.com/(?:(?!/i/).)*$
3520 .a[0-9].yimg.com/(?:(?!/i/).)*$
3526 <p>One of the most important jobs of <span class="APPLICATION">Privoxy</span> is to block banners. Many of
3527 these can be <span class="QUOTE">"blocked"</span> by the <tt class="LITERAL"><a href=
3528 "actions-file.html#FILTER">filter</a>{banners-by-size}</tt> action, which we enabled above, and which deletes
3529 the references to banner images from the pages while they are loaded, so the browser doesn't request them
3530 anymore, and hence they don't need to be blocked here. But this naturally doesn't catch all banners, and some
3531 people choose not to use filters, so we need a comprehensive list of patterns for banner URLs here, and apply
3532 the <tt class="LITERAL"><a href="actions-file.html#BLOCK">block</a></tt> action to them.</p>
3533 <p>First comes many generic patterns, which do most of the work, by matching typical domain and path name
3534 components of banners. Then comes a list of individual patterns for specific sites, which is omitted here to
3535 keep the example short:</p>
3536 <table border="0" bgcolor="#E0E0E0" width="100%">
3539 <pre class="SCREEN">##########################################################################
3540 # Block these fine banners:
3541 ##########################################################################
3542 { <a href="actions-file.html#BLOCK">+block{Banner ads.}</a> }
3550 /.*count(er)?\.(pl|cgi|exe|dll|asp|php[34]?)
3551 /(?:.*/)?(publicite|werbung|rekla(ma|me|am)|annonse|maino(kset|nta|s)?)/
3553 # Site-specific patterns (abbreviated):
3559 <p>It's quite remarkable how many advertisers actually call their banner servers ads.<tt class=
3560 "REPLACEABLE"><i>company</i></tt>.com, or call the directory in which the banners are stored literally
3561 <span class="QUOTE">"banners"</span>. So the above generic patterns are surprisingly effective.</p>
3562 <p>But being very generic, they necessarily also catch URLs that we don't want to block. The pattern <tt class=
3563 "LITERAL">.*ads.</tt> e.g. catches <span class="QUOTE">"nasty-<span class="emphasis"><i class=
3564 "EMPHASIS">ads</i></span>.nasty-corp.com"</span> as intended, but also <span class="QUOTE">"downlo<span class=
3565 "emphasis"><i class="EMPHASIS">ads</i></span>.sourcefroge.net"</span> or <span class="QUOTE">"<span class=
3566 "emphasis"><i class="EMPHASIS">ads</i></span>l.some-provider.net."</span> So here come some well-known
3567 exceptions to the <tt class="LITERAL">+<a href="actions-file.html#BLOCK">block</a></tt> section above.</p>
3568 <p>Note that these are exceptions to exceptions from the default! Consider the URL <span class=
3569 "QUOTE">"downloads.sourcefroge.net"</span>: Initially, all actions are deactivated, so it wouldn't get blocked.
3570 Then comes the defaults section, which matches the URL, but just deactivates the <tt class="LITERAL"><a href=
3571 "actions-file.html#BLOCK">block</a></tt> action once again. Then it matches <tt class="LITERAL">.*ads.</tt>, an
3572 exception to the general non-blocking policy, and suddenly <tt class="LITERAL"><a href=
3573 "actions-file.html#BLOCK">+block</a></tt> applies. And now, it'll match <tt class="LITERAL">.*loads.</tt>,
3574 where <tt class="LITERAL"><a href="actions-file.html#BLOCK">-block</a></tt> applies, so (unless it matches
3575 <span class="emphasis"><i class="EMPHASIS">again</i></span> further down) it ends up with no <tt class=
3576 "LITERAL"><a href="actions-file.html#BLOCK">block</a></tt> action applying.</p>
3577 <table border="0" bgcolor="#E0E0E0" width="100%">
3580 <pre class="SCREEN">##########################################################################
3581 # Save some innocent victims of the above generic block patterns:
3582 ##########################################################################
3586 { -<a href="actions-file.html#BLOCK">block</a> }
3587 adv[io]*. # (for advogato.org and advice.*)
3588 adsl. # (has nothing to do with ads)
3589 adobe. # (has nothing to do with ads either)
3590 ad[ud]*. # (adult.* and add.*)
3591 .edu # (universities don't host banners (yet!))
3592 .*loads. # (downloads, uploads etc)
3600 www.globalintersec.com/adv # (adv = advanced)
3601 www.ugu.com/sui/ugu/adv</pre>
3605 <p>Filtering source code can have nasty side effects, so make an exception for our friends at sourceforge.net,
3606 and all paths with <span class="QUOTE">"cvs"</span> in them. Note that <tt class="LITERAL">-<a href=
3607 "actions-file.html#FILTER">filter</a></tt> disables <span class="emphasis"><i class="EMPHASIS">all</i></span>
3608 filters in one fell swoop!</p>
3609 <table border="0" bgcolor="#E0E0E0" width="100%">
3612 <pre class="SCREEN"># Don't filter code!
3614 { -<a href="actions-file.html#FILTER">filter</a> }
3619 .sourceforge.net</pre>
3623 <p>The actual <tt class="FILENAME">default.action</tt> is of course much more comprehensive, but we hope this
3624 example made clear how it works.</p>
3627 <h3 class="SECT3"><a name="USER-ACTION" id="USER-ACTION">8.7.3. user.action</a></h3>
3628 <p>So far we are painting with a broad brush by setting general policies, which would be a reasonable starting
3629 point for many people. Now, you might want to be more specific and have customized rules that are more suitable
3630 to your personal habits and preferences. These would be for narrowly defined situations like your ISP or your
3631 bank, and should be placed in <tt class="FILENAME">user.action</tt>, which is parsed after all other actions
3632 files and hence has the last word, over-riding any previously defined actions. <tt class=
3633 "FILENAME">user.action</tt> is also a <span class="emphasis"><i class="EMPHASIS">safe</i></span> place for your
3634 personal settings, since <tt class="FILENAME">default.action</tt> is actively maintained by the <span class=
3635 "APPLICATION">Privoxy</span> developers and you'll probably want to install updated versions from time to
3637 <p>So let's look at a few examples of things that one might typically do in <tt class=
3638 "FILENAME">user.action</tt>:</p>
3639 <table border="0" bgcolor="#E0E0E0" width="100%">
3642 <pre class="SCREEN"># My user.action file. <fred@example.com></pre>
3646 <p>As <a href="actions-file.html#ALIASES">aliases</a> are local to the actions file that they are defined in,
3647 you can't use the ones from <tt class="FILENAME">default.action</tt>, unless you repeat them here:</p>
3648 <table border="0" bgcolor="#E0E0E0" width="100%">
3651 <pre class="SCREEN"># Aliases are local to the file they are defined in.
3652 # (Re-)define aliases for this file:
3656 # These aliases just save typing later, and the alias names should
3657 # be self explanatory.
3659 +crunch-all-cookies = +crunch-incoming-cookies +crunch-outgoing-cookies
3660 -crunch-all-cookies = -crunch-incoming-cookies -crunch-outgoing-cookies
3661 allow-all-cookies = -crunch-all-cookies -session-cookies-only
3662 allow-popups = -filter{all-popups}
3663 +block-as-image = +block{Blocked as image.} +handle-as-image
3664 -block-as-image = -block
3666 # These aliases define combinations of actions that are useful for
3667 # certain types of sites:
3669 fragile = -block -crunch-all-cookies -filter -fast-redirects -hide-referrer
3670 shop = -crunch-all-cookies allow-popups
3672 # Allow ads for selected useful free sites:
3674 allow-ads = -block -filter{banners-by-size} -filter{banners-by-link}
3676 # Alias for specific file types that are text, but might have conflicting
3677 # MIME types. We want the browser to force these to be text documents.
3678 handle-as-text = -<a href="actions-file.html#FILTER">filter</a> +-<a href=
3679 "actions-file.html#CONTENT-TYPE-OVERWRITE">content-type-overwrite{text/plain}</a> +-<a href=
3680 "actions-file.html#FORCE-TEXT-MODE">force-text-mode</a> -<a href=
3681 "actions-file.html#HIDE-CONTENT-DISPOSITION">hide-content-disposition</a></pre>
3685 <p>Say you have accounts on some sites that you visit regularly, and you don't want to have to log in manually
3686 each time. So you'd like to allow persistent cookies for these sites. The <tt class=
3687 "LITERAL">allow-all-cookies</tt> alias defined above does exactly that, i.e. it disables crunching of cookies
3688 in any direction, and the processing of cookies to make them only temporary.</p>
3689 <table border="0" bgcolor="#E0E0E0" width="100%">
3692 <pre class="SCREEN">{ allow-all-cookies }
3700 <p>Your bank is allergic to some filter, but you don't know which, so you disable them all:</p>
3701 <table border="0" bgcolor="#E0E0E0" width="100%">
3704 <pre class="SCREEN">{ -<a href="actions-file.html#FILTER">filter</a> }
3705 .your-home-banking-site.com</pre>
3709 <p>Some file types you may not want to filter for various reasons:</p>
3710 <table border="0" bgcolor="#E0E0E0" width="100%">
3713 <pre class="SCREEN"># Technical documentation is likely to contain strings that might
3714 # erroneously get altered by the JavaScript-oriented filters:
3719 # And this stupid host sends streaming video with a wrong MIME type,
3720 # so that Privoxy thinks it is getting HTML and starts filtering:
3722 stupid-server.example.com/</pre>
3726 <p>Example of a simple <a href="actions-file.html#BLOCK">block</a> action. Say you've seen an ad on your
3727 favourite page on example.com that you want to get rid of. You have right-clicked the image, selected
3728 <span class="QUOTE">"copy image location"</span> and pasted the URL below while removing the leading http://,
3729 into a <tt class="LITERAL">{ +block{} }</tt> section. Note that <tt class="LITERAL">{ +handle-as-image }</tt>
3730 need not be specified, since all URLs ending in <tt class="LITERAL">.gif</tt> will be tagged as images by the
3731 general rules as set in default.action anyway:</p>
3732 <table border="0" bgcolor="#E0E0E0" width="100%">
3735 <pre class="SCREEN">{ +<a href="actions-file.html#BLOCK">block</a>{Nasty ads.} }
3736 www.example.com/nasty-ads/sponsor\.gif
3737 another.example.net/more/junk/here/</pre>
3741 <p>The URLs of dynamically generated banners, especially from large banner farms, often don't use the
3742 well-known image file name extensions, which makes it impossible for <span class="APPLICATION">Privoxy</span>
3743 to guess the file type just by looking at the URL. You can use the <tt class="LITERAL">+block-as-image</tt>
3744 alias defined above for these cases. Note that objects which match this rule but then turn out NOT to be an
3745 image are typically rendered as a <span class="QUOTE">"broken image"</span> icon by the browser. Use
3747 <table border="0" bgcolor="#E0E0E0" width="100%">
3750 <pre class="SCREEN">{ +block-as-image }
3754 ar.atwola.com/</pre>
3758 <p>Now you noticed that the default configuration breaks Forbes Magazine, but you were too lazy to find out
3759 which action is the culprit, and you were again too lazy to give <a href="contact.html">feedback</a>, so you
3760 just used the <tt class="LITERAL">fragile</tt> alias on the site, and -- <span class="emphasis"><i class=
3761 "EMPHASIS">whoa!</i></span> -- it worked. The <tt class="LITERAL">fragile</tt> aliases disables those actions
3762 that are most likely to break a site. Also, good for testing purposes to see if it is <span class=
3763 "APPLICATION">Privoxy</span> that is causing the problem or not. We later find other regular sites that
3764 misbehave, and add those to our personalized list of troublemakers:</p>
3765 <table border="0" bgcolor="#E0E0E0" width="100%">
3768 <pre class="SCREEN">{ fragile }
3775 <p>You like the <span class="QUOTE">"fun"</span> text replacements in <tt class="FILENAME">default.filter</tt>,
3776 but it is disabled in the distributed actions file. So you'd like to turn it on in your private, update-safe
3777 config, once and for all:</p>
3778 <table border="0" bgcolor="#E0E0E0" width="100%">
3781 <pre class="SCREEN">{ +<a href="actions-file.html#FILTER-FUN">filter{fun}</a> }
3782 / # For ALL sites!</pre>
3786 <p>Note that the above is not really a good idea: There are exceptions to the filters in <tt class=
3787 "FILENAME">default.action</tt> for things that really shouldn't be filtered, like code on CVS->Web
3788 interfaces. Since <tt class="FILENAME">user.action</tt> has the last word, these exceptions won't be valid for
3789 the <span class="QUOTE">"fun"</span> filtering specified here.</p>
3790 <p>You might also worry about how your favourite free websites are funded, and find that they rely on
3791 displaying banner advertisements to survive. So you might want to specifically allow banners for those sites
3792 that you feel provide value to you:</p>
3793 <table border="0" bgcolor="#E0E0E0" width="100%">
3796 <pre class="SCREEN">{ allow-ads }
3803 <p>Note that <tt class="LITERAL">allow-ads</tt> has been aliased to <tt class="LITERAL">-<a href=
3804 "actions-file.html#BLOCK">block</a></tt>, <tt class="LITERAL">-<a href=
3805 "actions-file.html#FILTER-BANNERS-BY-SIZE">filter{banners-by-size}</a></tt>, and <tt class="LITERAL">-<a href=
3806 "actions-file.html#FILTER-BANNERS-BY-LINK">filter{banners-by-link}</a></tt> above.</p>
3807 <p>Invoke another alias here to force an over-ride of the MIME type <tt class="LITERAL">application/x-sh</tt>
3808 which typically would open a download type dialog. In my case, I want to look at the shell script, and then I
3809 can save it should I choose to.</p>
3810 <table border="0" bgcolor="#E0E0E0" width="100%">
3813 <pre class="SCREEN">{ handle-as-text }
3818 <p><tt class="FILENAME">user.action</tt> is generally the best place to define exceptions and additions to the
3819 default policies of <tt class="FILENAME">default.action</tt>. Some actions are safe to have their default
3820 policies set here though. So let's set a default policy to have a <span class="QUOTE">"blank"</span> image as
3821 opposed to the checkerboard pattern for <span class="emphasis"><i class="EMPHASIS">ALL</i></span> sites.
3822 <span class="QUOTE">"/"</span> of course matches all URL paths and patterns:</p>
3823 <table border="0" bgcolor="#E0E0E0" width="100%">
3826 <pre class="SCREEN">{ +<a href="actions-file.html#SET-IMAGE-BLOCKER">set-image-blocker{blank}</a> }
3834 <div class="NAVFOOTER">
3835 <hr align="left" width="100%">
3836 <table summary="Footer navigation table" width="100%" border="0" cellpadding="0" cellspacing="0">
3838 <td width="33%" align="left" valign="top"><a href="config.html" accesskey="P">Prev</a></td>
3839 <td width="34%" align="center" valign="top"><a href="index.html" accesskey="H">Home</a></td>
3840 <td width="33%" align="right" valign="top"><a href="filter-file.html" accesskey="N">Next</a></td>
3843 <td width="33%" align="left" valign="top">The Main Configuration File</td>
3844 <td width="34%" align="center" valign="top"> </td>
3845 <td width="33%" align="right" valign="top">Filter Files</td>