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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 <p>Client tag patterns are not set based on HTTP headers but based on the client's IP address. Users can enable
503 them themselves, but the Privoxy admin controls which tags are available and what their effect is.</p>
504 <p>After a client-specific tag has been defined with the <a href=
505 "config.html#CLIENT-SPECIFIC-TAG">client-specific-tag</a>, directive, action sections can be activated based on
506 the tag by using a CLIENT-TAG pattern. The CLIENT-TAG pattern is evaluated at the same priority as URL
507 patterns, as a result the last matching pattern wins. Tags that are created based on client or server headers
508 are evaluated later on and can overrule CLIENT-TAG and URL patterns!</p>
509 <p>The tag is set for all requests that come from clients that requested it to be set. Note that "clients" are
510 differentiated by IP address, if the IP address changes the tag has to be requested again.</p>
511 <p>Clients can request tags to be set by using the CGI interface <a href=
512 "http://config.privoxy.org/client-tags" target="_top">http://config.privoxy.org/client-tags</a>.</p>
514 <table border="0" bgcolor="#E0E0E0" width="100%">
517 <pre class="SCREEN"> # If the admin defined the client-specific-tag circumvent-blocks,
518 # and the request comes from a client that previously requested
519 # the tag to be set, overrule all previous +block actions that
520 # are enabled based on URL to CLIENT-TAG patterns.
522 CLIENT-TAG:^circumvent-blocks$
524 # This section is not overruled because it's located after
526 {+block{Nobody is supposed to request this.}}
527 example.org/blocked-example-page</pre>
534 <h2 class="SECT2"><a name="ACTIONS" id="ACTIONS">8.5. Actions</a></h2>
535 <p>All actions are disabled by default, until they are explicitly enabled somewhere in an actions file. Actions
536 are turned on if preceded with a <span class="QUOTE">"+"</span>, and turned off if preceded with a <span class=
537 "QUOTE">"-"</span>. So a <tt class="LITERAL">+action</tt> means <span class="QUOTE">"do that action"</span>, e.g.
538 <tt class="LITERAL">+block</tt> means <span class="QUOTE">"please block URLs that match the following
539 patterns"</span>, and <tt class="LITERAL">-block</tt> means <span class="QUOTE">"don't block URLs that match the
540 following patterns, even if <tt class="LITERAL">+block</tt> previously applied."</span></p>
541 <p>Again, actions are invoked by placing them on a line, enclosed in curly braces and separated by whitespace,
542 like in <tt class="LITERAL">{+some-action -some-other-action{some-parameter}}</tt>, followed by a list of URL
543 patterns, one per line, to which they apply. Together, the actions line and the following pattern lines make up a
544 section of the actions file.</p>
545 <p>Actions fall into three categories:</p>
548 <p>Boolean, i.e the action can only be <span class="QUOTE">"enabled"</span> or <span class=
549 "QUOTE">"disabled"</span>. Syntax:</p>
550 <table border="0" bgcolor="#E0E0E0" width="90%">
553 <pre class="SCREEN"> +<tt class="REPLACEABLE"><i>name</i></tt> # enable action <tt class=
554 "REPLACEABLE"><i>name</i></tt>
555 -<tt class="REPLACEABLE"><i>name</i></tt> # disable action <tt class="REPLACEABLE"><i>name</i></tt></pre>
559 <p>Example: <tt class="LITERAL">+handle-as-image</tt></p>
562 <p>Parameterized, where some value is required in order to enable this type of action. Syntax:</p>
563 <table border="0" bgcolor="#E0E0E0" width="90%">
566 <pre class="SCREEN"> +<tt class="REPLACEABLE"><i>name</i></tt>{<tt class=
567 "REPLACEABLE"><i>param</i></tt>} # enable action and set parameter to <tt class=
568 "REPLACEABLE"><i>param</i></tt>,
569 # overwriting parameter from previous match if necessary
570 -<tt class="REPLACEABLE"><i>name</i></tt> # disable action. The parameter can be omitted</pre>
574 <p>Note that if the URL matches multiple positive forms of a parameterized action, the last match wins, i.e.
575 the params from earlier matches are simply ignored.</p>
576 <p>Example: <tt class="LITERAL">+hide-user-agent{Mozilla/5.0 (X11; U; FreeBSD i386; en-US; rv:1.8.1.4)
577 Gecko/20070602 Firefox/2.0.0.4}</tt></p>
580 <p>Multi-value. These look exactly like parameterized actions, but they behave differently: If the action
581 applies multiple times to the same URL, but with different parameters, <span class="emphasis"><i class=
582 "EMPHASIS">all</i></span> the parameters from <span class="emphasis"><i class="EMPHASIS">all</i></span>
583 matches are remembered. This is used for actions that can be executed for the same request repeatedly, like
584 adding multiple headers, or filtering through multiple filters. Syntax:</p>
585 <table border="0" bgcolor="#E0E0E0" width="90%">
588 <pre class="SCREEN"> +<tt class="REPLACEABLE"><i>name</i></tt>{<tt class=
589 "REPLACEABLE"><i>param</i></tt>} # enable action and add <tt class=
590 "REPLACEABLE"><i>param</i></tt> to the list of parameters
591 -<tt class="REPLACEABLE"><i>name</i></tt>{<tt class=
592 "REPLACEABLE"><i>param</i></tt>} # remove the parameter <tt class=
593 "REPLACEABLE"><i>param</i></tt> from the list of parameters
594 # If it was the last one left, disable the action.
596 "REPLACEABLE"><i>-name</i></tt> # disable this action completely and remove all parameters from the list</pre>
600 <p>Examples: <tt class="LITERAL">+add-header{X-Fun-Header: Some text}</tt> and <tt class=
601 "LITERAL">+filter{html-annoyances}</tt></p>
604 <p>If nothing is specified in any actions file, no <span class="QUOTE">"actions"</span> are taken. So in this
605 case <span class="APPLICATION">Privoxy</span> would just be a normal, non-blocking, non-filtering proxy. You must
606 specifically enable the privacy and blocking features you need (although the provided default actions files will
607 give a good starting point).</p>
608 <p>Later defined action sections always over-ride earlier ones of the same type. So exceptions to any rules you
609 make, should come in the latter part of the file (or in a file that is processed later when using multiple
610 actions files such as <tt class="FILENAME">user.action</tt>). For multi-valued actions, the actions are applied
611 in the order they are specified. Actions files are processed in the order they are defined in <tt class=
612 "FILENAME">config</tt> (the default installation has three actions files). It also quite possible for any given
613 URL to match more than one <span class="QUOTE">"pattern"</span> (because of wildcards and regular expressions),
614 and thus to trigger more than one set of actions! Last match wins.</p>
615 <p>The list of valid <span class="APPLICATION">Privoxy</span> actions are:</p>
617 <h4 class="SECT3"><a name="ADD-HEADER" id="ADD-HEADER">8.5.1. add-header</a></h4>
618 <div class="VARIABLELIST">
620 <dt>Typical use:</dt>
622 <p>Confuse log analysis, custom applications</p>
626 <p>Sends a user defined HTTP header to the web server.</p>
634 <p>Any string value is possible. Validity of the defined HTTP headers is not checked. It is recommended
635 that you use the <span class="QUOTE">"<tt class="LITERAL">X-</tt>"</span> prefix for custom headers.</p>
639 <p>This action may be specified multiple times, in order to define multiple headers. This is rarely
640 needed for the typical user. If you don't know what <span class="QUOTE">"HTTP headers"</span> are, you
641 definitely don't need to worry about this one.</p>
642 <p>Headers added by this action are not modified by other actions.</p>
644 <dt>Example usage:</dt>
646 <table border="0" bgcolor="#E0E0E0" width="90%">
649 <pre class="SCREEN"> # Add a DNT ("Do not track") header to all requests,
650 # event to those that already have one.
652 # This is just an example, not a recommendation.
654 # There is no reason to believe that user-tracking websites care
655 # about the DNT header and depending on the User-Agent, adding the
656 # header may make user-tracking easier.
657 {+add-header{DNT: 1}}
667 <h4 class="SECT3"><a name="BLOCK" id="BLOCK">8.5.2. block</a></h4>
668 <div class="VARIABLELIST">
670 <dt>Typical use:</dt>
672 <p>Block ads or other unwanted content</p>
676 <p>Requests for URLs to which this action applies are blocked, i.e. the requests are trapped by
677 <span class="APPLICATION">Privoxy</span> and the requested URL is never retrieved, but is answered
678 locally with a substitute page or image, as determined by the <tt class="LITERAL"><a href=
679 "actions-file.html#HANDLE-AS-IMAGE">handle-as-image</a></tt>, <tt class="LITERAL"><a href=
680 "actions-file.html#SET-IMAGE-BLOCKER">set-image-blocker</a></tt>, and <tt class="LITERAL"><a href=
681 "actions-file.html#HANDLE-AS-EMPTY-DOCUMENT">handle-as-empty-document</a></tt> actions.</p>
685 <p>Parameterized.</p>
689 <p>A block reason that should be given to the user.</p>
693 <p><span class="APPLICATION">Privoxy</span> sends a special <span class="QUOTE">"BLOCKED"</span> page for
694 requests to blocked pages. This page contains the block reason given as parameter, a link to find out why
695 the block action applies, and a click-through to the blocked content (the latter only if the force
696 feature is available and enabled).</p>
697 <p>A very important exception occurs if <span class="emphasis"><i class="EMPHASIS">both</i></span>
698 <tt class="LITERAL">block</tt> and <tt class="LITERAL"><a href=
699 "actions-file.html#HANDLE-AS-IMAGE">handle-as-image</a></tt>, apply to the same request: it will then be
700 replaced by an image. If <tt class="LITERAL"><a href=
701 "actions-file.html#SET-IMAGE-BLOCKER">set-image-blocker</a></tt> (see below) also applies, the type of
702 image will be determined by its parameter, if not, the standard checkerboard pattern is sent.</p>
703 <p>It is important to understand this process, in order to understand how <span class=
704 "APPLICATION">Privoxy</span> deals with ads and other unwanted content. Blocking is a core feature, and
705 one upon which various other features depend.</p>
706 <p>The <tt class="LITERAL"><a href="actions-file.html#FILTER">filter</a></tt> action can perform a very
707 similar task, by <span class="QUOTE">"blocking"</span> banner images and other content through rewriting
708 the relevant URLs in the document's HTML source, so they don't get requested in the first place. Note
709 that this is a totally different technique, and it's easy to confuse the two.</p>
711 <dt>Example usage (section):</dt>
713 <table border="0" bgcolor="#E0E0E0" width="90%">
716 <pre class="SCREEN"> {+block{No nasty stuff for you.}}
717 # Block and replace with "blocked" page
718 .nasty-stuff.example.com
720 {+block{Doubleclick banners.} +handle-as-image}
721 # Block and replace with image
725 {+block{Layered ads.} +handle-as-empty-document}
726 # Block and then ignore
727 adserver.example.net/.*\.js$</pre>
736 <h4 class="SECT3"><a name="CHANGE-X-FORWARDED-FOR" id="CHANGE-X-FORWARDED-FOR">8.5.3.
737 change-x-forwarded-for</a></h4>
738 <div class="VARIABLELIST">
740 <dt>Typical use:</dt>
742 <p>Improve privacy by not forwarding the source of the request in the HTTP headers.</p>
746 <p>Deletes the <span class="QUOTE">"X-Forwarded-For:"</span> HTTP header from the client request, or adds
751 <p>Parameterized.</p>
757 <p><span class="QUOTE">"block"</span> to delete the header.</p>
760 <p><span class="QUOTE">"add"</span> to create the header (or append the client's IP address to an
761 already existing one).</p>
767 <p>It is safe and recommended to use <tt class="LITERAL">block</tt>.</p>
768 <p>Forwarding the source address of the request may make sense in some multi-user setups but is also a
771 <dt>Example usage:</dt>
773 <table border="0" bgcolor="#E0E0E0" width="90%">
776 <pre class="SCREEN"> +change-x-forwarded-for{block}</pre>
785 <h4 class="SECT3"><a name="CLIENT-HEADER-FILTER" id="CLIENT-HEADER-FILTER">8.5.4. client-header-filter</a></h4>
786 <div class="VARIABLELIST">
788 <dt>Typical use:</dt>
790 <p>Rewrite or remove single client headers.</p>
794 <p>All client headers to which this action applies are filtered on-the-fly through the specified regular
795 expression based substitutions.</p>
803 <p>The name of a client-header filter, as defined in one of the <a href="filter-file.html">filter
808 <p>Client-header filters are applied to each header on its own, not to all at once. This makes it easier
809 to diagnose problems, but on the downside you can't write filters that only change header x if header y's
810 value is z. You can do that by using tags though.</p>
811 <p>Client-header filters are executed after the other header actions have finished and use their output
813 <p>If the request URI gets changed, <span class="APPLICATION">Privoxy</span> will detect that and use the
814 new one. This can be used to rewrite the request destination behind the client's back, for example to
815 specify a Tor exit relay for certain requests.</p>
816 <p>Note that to change the destination host for <a href=
817 "actions-file.html#HTTPS-INSPECTION">https-inspected</a> requests a protocol and host has to be added to
819 <p>If <a href="actions-file.html#HTTPS-INSPECTION">https inspection</a> is enabled, the protocol can be
820 downgraded from https to http but upgrading a request from http to https is currently not supported.</p>
821 <p>After detecting a rewrite, <span class="APPLICATION">Privoxy</span> does not update the actions used
822 for the request based on the new host.</p>
823 <p>Please refer to the <a href="filter-file.html">filter file chapter</a> to learn which client-header
824 filters are available by default, and how to create your own.</p>
826 <dt>Example usage (section):</dt>
828 <table border="0" bgcolor="#E0E0E0" width="90%">
831 <pre class="SCREEN"> # Hide Tor exit notation in Host and Referer Headers
832 {+client-header-filter{hide-tor-exit-notation}}
842 <h4 class="SECT3"><a name="CLIENT-BODY-FILTER" id="CLIENT-BODY-FILTER">8.5.5. client-body-filter</a></h4>
843 <div class="VARIABLELIST">
845 <dt>Typical use:</dt>
847 <p>Rewrite or remove client request body.</p>
851 <p>All request bodies to which this action applies are filtered on-the-fly through the specified regular
852 expression based substitutions.</p>
860 <p>The name of a client-body filter, as defined in one of the <a href="filter-file.html">filter
865 <p>Please refer to the <a href="filter-file.html">filter file chapter</a> to learn how to create your own
866 client-body filters.</p>
867 <p>The distribution <tt class="FILENAME">default.filter</tt> file contains a selection of client-body
868 filters for example purposes.</p>
869 <p>The amount of data that can be filtered is limited by the <tt class="LITERAL"><a href=
870 "config.html#BUFFER-LIMIT">buffer-limit</a></tt> option in the main <a href="config.html">config
871 file</a>. The default is 4096 KB (4 Megs). Once this limit is exceeded, the whole request body is passed
872 through unfiltered.</p>
874 <dt>Example usage (section):</dt>
876 <table border="0" bgcolor="#E0E0E0" width="90%">
879 <pre class="SCREEN"> # Remove "test" everywhere in the request body
880 {+client-body-filter{remove-test}}
890 <h4 class="SECT3"><a name="CLIENT-BODY-TAGGER" id="CLIENT-BODY-TAGGER">8.5.6. client-body-tagger</a></h4>
891 <div class="VARIABLELIST">
893 <dt>Typical use:</dt>
895 <p>Block requests based on the content of the body data.</p>
899 <p>Client request bodies to which this action applies are filtered on-the-fly through the specified
900 regular expression based substitutions, the result is used as tag.</p>
908 <p>The name of a client-body tagger, as defined in one of the <a href="filter-file.html">filter
913 <p>Please refer to the <a href="filter-file.html">filter file chapter</a> to learn how to create your own
914 client-body tagger.</p>
915 <p>Client-body taggers are applied to each request body on its own, and as the body isn't modified, each
916 tagger "sees" the original.</p>
917 <p>Chunk-encoded request bodies currently can't be tagged. Request bodies larger than the buffer-limit
918 can't be tagged either.</p>
920 <dt>Example usage (section):</dt>
922 <table border="0" bgcolor="#E0E0E0" width="90%">
925 <pre class="SCREEN"> # Apply blafasel tagger.
926 {+client-body-tagger{blafasel}}
929 # Block request based on the tag created by the blafasel tagger.
930 {+block{Request body contains blafasel}}
931 TAG:^content contains blafasel$</pre>
940 <h4 class="SECT3"><a name="CLIENT-HEADER-TAGGER" id="CLIENT-HEADER-TAGGER">8.5.7. client-header-tagger</a></h4>
941 <div class="VARIABLELIST">
943 <dt>Typical use:</dt>
945 <p>Block requests based on their headers.</p>
949 <p>Client headers to which this action applies are filtered on-the-fly through the specified regular
950 expression based substitutions, the result is used as tag.</p>
958 <p>The name of a client-header tagger, as defined in one of the <a href="filter-file.html">filter
963 <p>Client-header taggers are applied to each header on its own, and as the header isn't modified, each
964 tagger <span class="QUOTE">"sees"</span> the original.</p>
965 <p>Client-header taggers are the first actions that are executed and their tags can be used to control
966 every other action.</p>
968 <dt>Example usage (section):</dt>
970 <table border="0" bgcolor="#E0E0E0" width="90%">
973 <pre class="SCREEN"> # Tag every request with the User-Agent header
974 {+client-header-tagger{user-agent}}
977 # Tagging itself doesn't change the action
978 # settings, sections with TAG patterns do:
980 # If it's a download agent, use a different forwarding proxy,
981 # show the real User-Agent and make sure resume works.
982 {+forward-override{forward-socks5 10.0.0.2:2222 .} \
983 -hide-if-modified-since \
984 -overwrite-last-modified \
989 TAG:^User-Agent: NetBSD-ftp/
990 TAG:^User-Agent: Novell ZYPP Installer
991 TAG:^User-Agent: RPM APT-HTTP/
992 TAG:^User-Agent: fetch libfetch/
993 TAG:^User-Agent: Ubuntu APT-HTTP/
994 TAG:^User-Agent: MPlayer/</pre>
998 <table border="0" bgcolor="#E0E0E0" width="90%">
1001 <pre class="SCREEN"> # Tag all requests with the Range header set
1002 {+client-header-tagger{range-requests}}
1005 # Disable filtering for the tagged requests.
1007 # With filtering enabled Privoxy would remove the Range headers
1008 # to be able to filter the whole response. The downside is that
1009 # it prevents clients from resuming downloads or skipping over
1010 # parts of multimedia files.
1011 {-filter -deanimate-gifs}
1012 TAG:^RANGE-REQUEST$</pre>
1016 <table border="0" bgcolor="#E0E0E0" width="90%">
1019 <pre class="SCREEN"> # Tag all requests with the client IP address
1021 # (Technically the client IP address isn't included in the
1022 # client headers but client-header taggers can set it anyway.
1023 # For details see the tagger in default.filter)
1024 {+client-header-tagger{client-ip-address}}
1027 # Change forwarding settings for requests coming from address 10.0.0.1
1028 {+forward-override{forward-socks5 127.0.1.2:2222 .}}
1029 TAG:^IP-ADDRESS: 10\.0\.0\.1$</pre>
1038 <h4 class="SECT3"><a name="CONTENT-TYPE-OVERWRITE" id="CONTENT-TYPE-OVERWRITE">8.5.8.
1039 content-type-overwrite</a></h4>
1040 <div class="VARIABLELIST">
1042 <dt>Typical use:</dt>
1044 <p>Stop useless download menus from popping up, or change the browser's rendering mode</p>
1048 <p>Replaces the <span class="QUOTE">"Content-Type:"</span> HTTP server header.</p>
1052 <p>Parameterized.</p>
1060 <p>The <span class="QUOTE">"Content-Type:"</span> HTTP server header is used by the browser to decide
1061 what to do with the document. The value of this header can cause the browser to open a download menu
1062 instead of displaying the document by itself, even if the document's format is supported by the
1064 <p>The declared content type can also affect which rendering mode the browser chooses. If XHTML is
1065 delivered as <span class="QUOTE">"text/html"</span>, many browsers treat it as yet another broken HTML
1066 document. If it is send as <span class="QUOTE">"application/xml"</span>, browsers with XHTML support will
1067 only display it, if the syntax is correct.</p>
1068 <p>If you see a web site that proudly uses XHTML buttons, but sets <span class="QUOTE">"Content-Type:
1069 text/html"</span>, you can use <span class="APPLICATION">Privoxy</span> to overwrite it with <span class=
1070 "QUOTE">"application/xml"</span> and validate the web master's claim inside your XHTML-supporting
1071 browser. If the syntax is incorrect, the browser will complain loudly.</p>
1072 <p>You can also go the opposite direction: if your browser prints error messages instead of rendering a
1073 document falsely declared as XHTML, you can overwrite the content type with <span class=
1074 "QUOTE">"text/html"</span> and have it rendered as broken HTML document.</p>
1075 <p>By default <tt class="LITERAL">content-type-overwrite</tt> only replaces <span class=
1076 "QUOTE">"Content-Type:"</span> headers that look like some kind of text. If you want to overwrite it
1077 unconditionally, you have to combine it with <tt class="LITERAL"><a href=
1078 "actions-file.html#FORCE-TEXT-MODE">force-text-mode</a></tt>. This limitation exists for a reason, think
1079 twice before circumventing it.</p>
1080 <p>Most of the time it's easier to replace this action with a custom <tt class="LITERAL"><a href=
1081 "actions-file.html#SERVER-HEADER-FILTER">server-header filter</a></tt>. It allows you to activate it for
1082 every document of a certain site and it will still only replace the content types you aimed at.</p>
1083 <p>Of course you can apply <tt class="LITERAL">content-type-overwrite</tt> to a whole site and then make
1084 URL based exceptions, but it's a lot more work to get the same precision.</p>
1086 <dt>Example usage (sections):</dt>
1088 <table border="0" bgcolor="#E0E0E0" width="90%">
1091 <pre class="SCREEN"> # Check if www.example.net/ really uses valid XHTML
1092 { +content-type-overwrite{application/xml} }
1095 # but leave the content type unmodified if the URL looks like a style sheet
1096 {-content-type-overwrite}
1097 www.example.net/.*\.css$
1098 www.example.net/.*style</pre>
1107 <h4 class="SECT3"><a name="CRUNCH-CLIENT-HEADER" id="CRUNCH-CLIENT-HEADER">8.5.9. crunch-client-header</a></h4>
1108 <div class="VARIABLELIST">
1110 <dt>Typical use:</dt>
1112 <p>Remove a client header <span class="APPLICATION">Privoxy</span> has no dedicated action for.</p>
1116 <p>Deletes every header sent by the client that contains the string the user supplied as parameter.</p>
1120 <p>Parameterized.</p>
1128 <p>This action allows you to block client headers for which no dedicated <span class=
1129 "APPLICATION">Privoxy</span> action exists. <span class="APPLICATION">Privoxy</span> will remove every
1130 client header that contains the string you supplied as parameter.</p>
1131 <p>Regular expressions are <span class="emphasis"><i class="EMPHASIS">not supported</i></span> and you
1132 can't use this action to block different headers in the same request, unless they contain the same
1134 <p><tt class="LITERAL">crunch-client-header</tt> is only meant for quick tests. If you have to block
1135 several different headers, or only want to modify parts of them, you should use a <tt class=
1136 "LITERAL"><a href="actions-file.html#CLIENT-HEADER-FILTER">client-header filter</a></tt>.</p>
1137 <div class="WARNING">
1138 <table class="WARNING" border="1" width="90%">
1140 <td align="center"><b>Warning</b></td>
1144 <p>Don't block any header without understanding the consequences.</p>
1150 <dt>Example usage (section):</dt>
1152 <table border="0" bgcolor="#E0E0E0" width="90%">
1155 <pre class="SCREEN"> # Block the non-existent "Privacy-Violation:" client header
1156 { +crunch-client-header{Privacy-Violation:} }
1166 <h4 class="SECT3"><a name="CRUNCH-IF-NONE-MATCH" id="CRUNCH-IF-NONE-MATCH">8.5.10.
1167 crunch-if-none-match</a></h4>
1168 <div class="VARIABLELIST">
1170 <dt>Typical use:</dt>
1172 <p>Prevent yet another way to track the user's steps between sessions.</p>
1176 <p>Deletes the <span class="QUOTE">"If-None-Match:"</span> HTTP client header.</p>
1188 <p>Removing the <span class="QUOTE">"If-None-Match:"</span> HTTP client header is useful for filter
1189 testing, where you want to force a real reload instead of getting status code <span class=
1190 "QUOTE">"304"</span> which would cause the browser to use a cached copy of the page.</p>
1191 <p>It is also useful to make sure the header isn't used as a cookie replacement (unlikely but
1193 <p>Blocking the <span class="QUOTE">"If-None-Match:"</span> header shouldn't cause any caching problems,
1194 as long as the <span class="QUOTE">"If-Modified-Since:"</span> header isn't blocked or missing as
1196 <p>It is recommended to use this action together with <tt class="LITERAL"><a href=
1197 "actions-file.html#HIDE-IF-MODIFIED-SINCE">hide-if-modified-since</a></tt> and <tt class=
1198 "LITERAL"><a href="actions-file.html#OVERWRITE-LAST-MODIFIED">overwrite-last-modified</a></tt>.</p>
1200 <dt>Example usage (section):</dt>
1202 <table border="0" bgcolor="#E0E0E0" width="90%">
1205 <pre class="SCREEN"> # Let the browser revalidate cached documents but don't
1206 # allow the server to use the revalidation headers for user tracking.
1207 {+hide-if-modified-since{-60} \
1208 +overwrite-last-modified{randomize} \
1209 +crunch-if-none-match}
1219 <h4 class="SECT3"><a name="CRUNCH-INCOMING-COOKIES" id="CRUNCH-INCOMING-COOKIES">8.5.11.
1220 crunch-incoming-cookies</a></h4>
1221 <div class="VARIABLELIST">
1223 <dt>Typical use:</dt>
1225 <p>Prevent the web server from setting HTTP cookies on your system</p>
1229 <p>Deletes any <span class="QUOTE">"Set-Cookie:"</span> HTTP headers from server replies.</p>
1241 <p>This action is only concerned with <span class="emphasis"><i class="EMPHASIS">incoming</i></span> HTTP
1242 cookies. For <span class="emphasis"><i class="EMPHASIS">outgoing</i></span> HTTP cookies, use <tt class=
1243 "LITERAL"><a href="actions-file.html#CRUNCH-OUTGOING-COOKIES">crunch-outgoing-cookies</a></tt>. Use
1244 <span class="emphasis"><i class="EMPHASIS">both</i></span> to disable HTTP cookies completely.</p>
1245 <p>It makes <span class="emphasis"><i class="EMPHASIS">no sense at all</i></span> to use this action in
1246 conjunction with the <tt class="LITERAL"><a href=
1247 "actions-file.html#SESSION-COOKIES-ONLY">session-cookies-only</a></tt> action, since it would prevent the
1248 session cookies from being set. See also <tt class="LITERAL"><a href=
1249 "actions-file.html#FILTER-CONTENT-COOKIES">filter-content-cookies</a></tt>.</p>
1251 <dt>Example usage:</dt>
1253 <table border="0" bgcolor="#E0E0E0" width="90%">
1256 <pre class="SCREEN"> +crunch-incoming-cookies</pre>
1265 <h4 class="SECT3"><a name="CRUNCH-SERVER-HEADER" id="CRUNCH-SERVER-HEADER">8.5.12.
1266 crunch-server-header</a></h4>
1267 <div class="VARIABLELIST">
1269 <dt>Typical use:</dt>
1271 <p>Remove a server header <span class="APPLICATION">Privoxy</span> has no dedicated action for.</p>
1275 <p>Deletes every header sent by the server that contains the string the user supplied as parameter.</p>
1279 <p>Parameterized.</p>
1287 <p>This action allows you to block server headers for which no dedicated <span class=
1288 "APPLICATION">Privoxy</span> action exists. <span class="APPLICATION">Privoxy</span> will remove every
1289 server header that contains the string you supplied as parameter.</p>
1290 <p>Regular expressions are <span class="emphasis"><i class="EMPHASIS">not supported</i></span> and you
1291 can't use this action to block different headers in the same request, unless they contain the same
1293 <p><tt class="LITERAL">crunch-server-header</tt> is only meant for quick tests. If you have to block
1294 several different headers, or only want to modify parts of them, you should use a custom <tt class=
1295 "LITERAL"><a href="actions-file.html#SERVER-HEADER-FILTER">server-header filter</a></tt>.</p>
1296 <div class="WARNING">
1297 <table class="WARNING" border="1" width="90%">
1299 <td align="center"><b>Warning</b></td>
1303 <p>Don't block any header without understanding the consequences.</p>
1309 <dt>Example usage (section):</dt>
1311 <table border="0" bgcolor="#E0E0E0" width="90%">
1314 <pre class="SCREEN"> # Crunch server headers that try to prevent caching
1315 { +crunch-server-header{no-cache} }
1325 <h4 class="SECT3"><a name="CRUNCH-OUTGOING-COOKIES" id="CRUNCH-OUTGOING-COOKIES">8.5.13.
1326 crunch-outgoing-cookies</a></h4>
1327 <div class="VARIABLELIST">
1329 <dt>Typical use:</dt>
1331 <p>Prevent the web server from reading any HTTP cookies from your system</p>
1335 <p>Deletes any <span class="QUOTE">"Cookie:"</span> HTTP headers from client requests.</p>
1347 <p>This action is only concerned with <span class="emphasis"><i class="EMPHASIS">outgoing</i></span> HTTP
1348 cookies. For <span class="emphasis"><i class="EMPHASIS">incoming</i></span> HTTP cookies, use <tt class=
1349 "LITERAL"><a href="actions-file.html#CRUNCH-INCOMING-COOKIES">crunch-incoming-cookies</a></tt>. Use
1350 <span class="emphasis"><i class="EMPHASIS">both</i></span> to disable HTTP cookies completely.</p>
1351 <p>It makes <span class="emphasis"><i class="EMPHASIS">no sense at all</i></span> to use this action in
1352 conjunction with the <tt class="LITERAL"><a href=
1353 "actions-file.html#SESSION-COOKIES-ONLY">session-cookies-only</a></tt> action, since it would prevent the
1354 session cookies from being read.</p>
1356 <dt>Example usage:</dt>
1358 <table border="0" bgcolor="#E0E0E0" width="90%">
1361 <pre class="SCREEN"> +crunch-outgoing-cookies</pre>
1370 <h4 class="SECT3"><a name="DEANIMATE-GIFS" id="DEANIMATE-GIFS">8.5.14. deanimate-gifs</a></h4>
1371 <div class="VARIABLELIST">
1373 <dt>Typical use:</dt>
1375 <p>Stop those annoying, distracting animated GIF images.</p>
1379 <p>De-animate GIF animations, i.e. reduce them to their first or last image.</p>
1383 <p>Parameterized.</p>
1387 <p><span class="QUOTE">"last"</span> or <span class="QUOTE">"first"</span></p>
1391 <p>This will also shrink the images considerably (in bytes, not pixels!). If the option <span class=
1392 "QUOTE">"first"</span> is given, the first frame of the animation is used as the replacement. If
1393 <span class="QUOTE">"last"</span> is given, the last frame of the animation is used instead, which
1394 probably makes more sense for most banner animations, but also has the risk of not showing the entire
1395 last frame (if it is only a delta to an earlier frame).</p>
1396 <p>You can safely use this action with patterns that will also match non-GIF objects, because no attempt
1397 will be made at anything that doesn't look like a GIF.</p>
1399 <dt>Example usage:</dt>
1401 <table border="0" bgcolor="#E0E0E0" width="90%">
1404 <pre class="SCREEN"> +deanimate-gifs{last}</pre>
1413 <h4 class="SECT3"><a name="DELAY-RESPONSE" id="DELAY-RESPONSE">8.5.15. delay-response</a></h4>
1414 <div class="VARIABLELIST">
1416 <dt>Typical use:</dt>
1418 <p>Delay responses to the client to reduce the load</p>
1422 <p>Delays responses to the client by sending the response in ca. 10 byte chunks.</p>
1426 <p>Parameterized.</p>
1430 <p><span class="QUOTE">"Number of milliseconds"</span></p>
1434 <p>Sometimes when JavaScript code is used to fetch advertisements it doesn't respect Privoxy's blocks and
1435 retries to fetch the same resource again causing unnecessary load on the client.</p>
1436 <p>This action delays responses to the client and can be combined with <tt class="LITERAL"><a href=
1437 "actions-file.html#BLOCK">blocks</a></tt> to slow down the JavaScript code, thus reducing the load on the
1439 <p>When used without <tt class="LITERAL"><a href="actions-file.html#BLOCK">blocks</a></tt> the action can
1440 also be used to simulate a slow internet connection.</p>
1442 <dt>Example usage:</dt>
1444 <table border="0" bgcolor="#E0E0E0" width="90%">
1447 <pre class="SCREEN"> +delay-response{100}</pre>
1456 <h4 class="SECT3"><a name="DOWNGRADE-HTTP-VERSION" id="DOWNGRADE-HTTP-VERSION">8.5.16.
1457 downgrade-http-version</a></h4>
1458 <div class="VARIABLELIST">
1460 <dt>Typical use:</dt>
1462 <p>Work around (very rare) problems with HTTP/1.1</p>
1466 <p>Downgrades HTTP/1.1 client requests and server replies to HTTP/1.0.</p>
1478 <p>This is a left-over from the time when <span class="APPLICATION">Privoxy</span> didn't support
1479 important HTTP/1.1 features well. It is left here for the unlikely case that you experience
1480 HTTP/1.1-related problems with some server out there.</p>
1481 <p>Note that enabling this action is only a workaround. It should not be enabled for sites that work
1482 without it. While it shouldn't break any pages, it has an (usually negative) performance impact.</p>
1483 <p>If you come across a site where enabling this action helps, please report it, so the cause of the
1484 problem can be analyzed. If the problem turns out to be caused by a bug in <span class=
1485 "APPLICATION">Privoxy</span> it should be fixed so the following release works without the work
1488 <dt>Example usage (section):</dt>
1490 <table border="0" bgcolor="#E0E0E0" width="90%">
1493 <pre class="SCREEN"> {+downgrade-http-version}
1494 problem-host.example.com</pre>
1503 <h4 class="SECT3"><a name="EXTERNAL-FILTER" id="EXTERNAL-FILTER">8.5.17. external-filter</a></h4>
1504 <div class="VARIABLELIST">
1506 <dt>Typical use:</dt>
1508 <p>Modify content using a programming language of your choice.</p>
1512 <p>All instances of text-based type, most notably HTML and JavaScript, to which this action applies, can
1513 be filtered on-the-fly through the specified external filter. By default plain text documents are
1514 exempted from filtering, because web servers often use the <tt class="LITERAL">text/plain</tt> MIME type
1515 for all files whose type they don't know.)</p>
1523 <p>The name of an external content filter, as defined in the <a href="filter-file.html">filter file</a>.
1524 External filters can be defined in one or more files as defined by the <tt class="LITERAL"><a href=
1525 "config.html#FILTERFILE">filterfile</a></tt> option in the <a href="config.html">config file</a>.</p>
1526 <p>When used in its negative form, and without parameters, <span class="emphasis"><i class=
1527 "EMPHASIS">all</i></span> filtering with external filters is completely disabled.</p>
1531 <p>External filters are scripts or programs that can modify the content in case common <tt class=
1532 "LITERAL"><a href="actions-file.html#FILTER">filters</a></tt> aren't powerful enough. With the exception
1533 that this action doesn't use pcrs-based filters, the notes in the <tt class="LITERAL"><a href=
1534 "actions-file.html#FILTER">filter</a></tt> section apply.</p>
1535 <div class="WARNING">
1536 <table class="WARNING" border="1" width="90%">
1538 <td align="center"><b>Warning</b></td>
1542 <p>Currently external filters are executed with <span class="APPLICATION">Privoxy</span>'s
1543 privileges. Only use external filters you understand and trust.</p>
1548 <p>This feature is experimental, the <tt class="LITERAL"><a href=
1549 "filter-file.html#EXTERNAL-FILTER-SYNTAX">syntax</a></tt> may change in the future.</p>
1551 <dt>Example usage:</dt>
1553 <table border="0" bgcolor="#E0E0E0" width="90%">
1556 <pre class="SCREEN"> +external-filter{fancy-filter}</pre>
1565 <h4 class="SECT3"><a name="FAST-REDIRECTS" id="FAST-REDIRECTS">8.5.18. fast-redirects</a></h4>
1566 <div class="VARIABLELIST">
1568 <dt>Typical use:</dt>
1570 <p>Fool some click-tracking scripts and speed up indirect links.</p>
1574 <p>Detects redirection URLs and redirects the browser without contacting the redirection server
1579 <p>Parameterized.</p>
1585 <p><span class="QUOTE">"simple-check"</span> to just search for the string <span class=
1586 "QUOTE">"http://"</span> to detect redirection URLs.</p>
1589 <p><span class="QUOTE">"check-decoded-url"</span> to decode URLs (if necessary) before searching for
1590 redirection URLs.</p>
1596 <p>Many sites, like yahoo.com, don't just link to other sites. Instead, they will link to some script on
1597 their own servers, giving the destination as a parameter, which will then redirect you to the final
1598 target. URLs resulting from this scheme typically look like: <span class=
1599 "QUOTE">"http://www.example.org/click-tracker.cgi?target=http%3a//www.example.net/"</span>.</p>
1600 <p>Sometimes, there are even multiple consecutive redirects encoded in the URL. These redirections via
1601 scripts make your web browsing more traceable, since the server from which you follow such a link can see
1602 where you go to. Apart from that, valuable bandwidth and time is wasted, while your browser asks the
1603 server for one redirect after the other. Plus, it feeds the advertisers.</p>
1604 <p>This feature is currently not very smart and is scheduled for improvement. If it is enabled by
1605 default, you will have to create some exceptions to this action. It can lead to failures in several
1607 <p>Not every URLs with other URLs as parameters is evil. Some sites offer a real service that requires
1608 this information to work. For example a validation service needs to know, which document to validate.
1609 <tt class="LITERAL">fast-redirects</tt> assumes that every URL parameter that looks like another URL is a
1610 redirection target, and will always redirect to the last one. Most of the time the assumption is correct,
1611 but if it isn't, the user gets redirected anyway.</p>
1612 <p>Another failure occurs if the URL contains other parameters after the URL parameter. The URL:
1613 <span class="QUOTE">"http://www.example.org/?redirect=http%3a//www.example.net/&foo=bar"</span>.
1614 contains the redirection URL <span class="QUOTE">"http://www.example.net/"</span>, followed by another
1615 parameter. <tt class="LITERAL">fast-redirects</tt> doesn't know that and will cause a redirect to
1616 <span class="QUOTE">"http://www.example.net/&foo=bar"</span>. Depending on the target server
1617 configuration, the parameter will be silently ignored or lead to a <span class="QUOTE">"page not
1618 found"</span> error. You can prevent this problem by first using the <tt class="LITERAL"><a href=
1619 "actions-file.html#REDIRECT">redirect</a></tt> action to remove the last part of the URL, but it requires
1620 a little effort.</p>
1621 <p>To detect a redirection URL, <tt class="LITERAL">fast-redirects</tt> only looks for the string
1622 <span class="QUOTE">"http://"</span>, either in plain text (invalid but often used) or encoded as
1623 <span class="QUOTE">"http%3a//"</span>. Some sites use their own URL encoding scheme, encrypt the address
1624 of the target server or replace it with a database id. In these cases <tt class=
1625 "LITERAL">fast-redirects</tt> is fooled and the request reaches the redirection server where it probably
1628 <dt>Example usage:</dt>
1630 <table border="0" bgcolor="#E0E0E0" width="90%">
1633 <pre class="SCREEN"> { +fast-redirects{simple-check} }
1636 { +fast-redirects{check-decoded-url} }
1637 another.example.com/testing</pre>
1646 <h4 class="SECT3"><a name="FILTER" id="FILTER">8.5.19. filter</a></h4>
1647 <div class="VARIABLELIST">
1649 <dt>Typical use:</dt>
1651 <p>Get rid of HTML and JavaScript annoyances, banner advertisements (by size), do fun text replacements,
1652 add personalized effects, etc.</p>
1656 <p>All instances of text-based type, most notably HTML and JavaScript, to which this action applies, can
1657 be filtered on-the-fly through the specified regular expression based substitutions. (Note: as of version
1658 3.0.3 plain text documents are exempted from filtering, because web servers often use the <tt class=
1659 "LITERAL">text/plain</tt> MIME type for all files whose type they don't know.)</p>
1667 <p>The name of a content filter, as defined in the <a href="filter-file.html">filter file</a>. Filters
1668 can be defined in one or more files as defined by the <tt class="LITERAL"><a href=
1669 "config.html#FILTERFILE">filterfile</a></tt> option in the <a href="config.html">config file</a>.
1670 <tt class="FILENAME">default.filter</tt> is the collection of filters supplied by the developers. Locally
1671 defined filters should go in their own file, such as <tt class="FILENAME">user.filter</tt>.</p>
1672 <p>When used in its negative form, and without parameters, <span class="emphasis"><i class=
1673 "EMPHASIS">all</i></span> filtering is completely disabled.</p>
1677 <p>For your convenience, there are a number of pre-defined filters available in the distribution filter
1678 file that you can use. See the examples below for a list.</p>
1679 <p>Filtering requires buffering the page content, which may appear to slow down page rendering since
1680 nothing is displayed until all content has passed the filters. (The total time until the page is
1681 completely rendered doesn't change much, but it may be perceived as slower since the page is not
1682 incrementally displayed.) This effect will be more noticeable on slower connections.</p>
1683 <p><span class="QUOTE">"Rolling your own"</span> filters requires a knowledge of <a href=
1684 "https://en.wikipedia.org/wiki/Regular_expressions" target="_top"><span class="QUOTE">"Regular
1685 Expressions"</span></a> and <a href="https://en.wikipedia.org/wiki/Html" target="_top"><span class=
1686 "QUOTE">"HTML"</span></a>. This is very powerful feature, and potentially very intrusive. Filters should
1687 be used with caution, and where an equivalent <span class="QUOTE">"action"</span> is not available.</p>
1688 <p>The amount of data that can be filtered is limited by the <tt class="LITERAL"><a href=
1689 "config.html#BUFFER-LIMIT">buffer-limit</a></tt> option in the main <a href="config.html">config
1690 file</a>. The default is 4096 KB (4 Megs). Once this limit is exceeded, the buffered data, and all
1691 pending data, is passed through unfiltered.</p>
1692 <p>Inappropriate MIME types, such as zipped files, are not filtered at all. (Again, only text-based types
1693 except plain text). Encrypted SSL data (from HTTPS servers) cannot be filtered either, since this would
1694 violate the integrity of the secure transaction. In some situations it might be necessary to protect
1695 certain text, like source code, from filtering by defining appropriate <tt class="LITERAL">-filter</tt>
1697 <p>Compressed content can't be filtered either, but if <span class="APPLICATION">Privoxy</span> is
1698 compiled with zlib support and a supported compression algorithm is used (gzip or deflate), <span class=
1699 "APPLICATION">Privoxy</span> can first decompress the content and then filter it.</p>
1700 <p>If you use a <span class="APPLICATION">Privoxy</span> version without zlib support, but want filtering
1701 to work on as much documents as possible, even those that would normally be sent compressed, you must use
1702 the <tt class="LITERAL"><a href="actions-file.html#PREVENT-COMPRESSION">prevent-compression</a></tt>
1703 action in conjunction with <tt class="LITERAL">filter</tt>.</p>
1704 <p>Content filtering can achieve some of the same effects as the <tt class="LITERAL"><a href=
1705 "actions-file.html#BLOCK">block</a></tt> action, i.e. it can be used to block ads and banners. But the
1706 mechanism works quite differently. One effective use, is to block ad banners based on their size (see
1707 below), since many of these seem to be somewhat standardized.</p>
1708 <p><a href="contact.html">Feedback</a> with suggestions for new or improved filters is particularly
1710 <p>The below list has only the names and a one-line description of each predefined filter. There are
1711 <a href="filter-file.html#PREDEFINED-FILTERS">more verbose explanations</a> of what these filters do in
1712 the <a href="filter-file.html">filter file chapter</a>.</p>
1714 <dt>Example usage (with filters from the distribution <tt class="FILENAME">default.filter</tt> file). See
1715 <a href="filter-file.html#PREDEFINED-FILTERS">the Predefined Filters section</a> for more explanation on
1718 <p><a name="FILTER-JS-ANNOYANCES" id="FILTER-JS-ANNOYANCES"></a></p>
1719 <table border="0" bgcolor="#E0E0E0" width="90%">
1723 "SCREEN"> +filter{js-annoyances} # Get rid of particularly annoying JavaScript abuse.</pre>
1727 <p><a name="FILTER-JS-EVENTS" id="FILTER-JS-EVENTS"></a></p>
1728 <table border="0" bgcolor="#E0E0E0" width="90%">
1732 "SCREEN"> +filter{js-events} # Kill JavaScript event bindings and timers (Radically destructive! Only for extra nasty sites).</pre>
1736 <p><a name="FILTER-HTML-ANNOYANCES" id="FILTER-HTML-ANNOYANCES"></a></p>
1737 <table border="0" bgcolor="#E0E0E0" width="90%">
1741 "SCREEN"> +filter{html-annoyances} # Get rid of particularly annoying HTML abuse.</pre>
1745 <p><a name="FILTER-CONTENT-COOKIES" id="FILTER-CONTENT-COOKIES"></a></p>
1746 <table border="0" bgcolor="#E0E0E0" width="90%">
1750 "SCREEN"> +filter{content-cookies} # Kill cookies that come in the HTML or JS content.</pre>
1754 <p><a name="FILTER-REFRESH-TAGS" id="FILTER-REFRESH-TAGS"></a></p>
1755 <table border="0" bgcolor="#E0E0E0" width="90%">
1759 "SCREEN"> +filter{refresh-tags} # Kill automatic refresh tags if refresh time is larger than 9 seconds.</pre>
1763 <p><a name="FILTER-UNSOLICITED-POPUPS" id="FILTER-UNSOLICITED-POPUPS"></a></p>
1764 <table border="0" bgcolor="#E0E0E0" width="90%">
1767 <pre class="SCREEN"> +filter{unsolicited-popups} # Disable only unsolicited pop-up windows.</pre>
1771 <p><a name="FILTER-ALL-POPUPS" id="FILTER-ALL-POPUPS"></a></p>
1772 <table border="0" bgcolor="#E0E0E0" width="90%">
1775 <pre class="SCREEN"> +filter{all-popups} # Kill all popups in JavaScript and HTML.</pre>
1779 <p><a name="FILTER-IMG-REORDER" id="FILTER-IMG-REORDER"></a></p>
1780 <table border="0" bgcolor="#E0E0E0" width="90%">
1784 "SCREEN"> +filter{img-reorder} # Reorder attributes in <img> tags to make the banners-by-* filters more effective.</pre>
1788 <p><a name="FILTER-BANNERS-BY-SIZE" id="FILTER-BANNERS-BY-SIZE"></a></p>
1789 <table border="0" bgcolor="#E0E0E0" width="90%">
1792 <pre class="SCREEN"> +filter{banners-by-size} # Kill banners by size.</pre>
1796 <p><a name="FILTER-BANNERS-BY-LINK" id="FILTER-BANNERS-BY-LINK"></a></p>
1797 <table border="0" bgcolor="#E0E0E0" width="90%">
1801 "SCREEN"> +filter{banners-by-link} # Kill banners by their links to known clicktrackers.</pre>
1805 <p><a name="FILTER-WEBBUGS" id="FILTER-WEBBUGS"></a></p>
1806 <table border="0" bgcolor="#E0E0E0" width="90%">
1810 "SCREEN"> +filter{webbugs} # Squish WebBugs (1x1 invisible GIFs used for user tracking).</pre>
1814 <p><a name="FILTER-TINY-TEXTFORMS" id="FILTER-TINY-TEXTFORMS"></a></p>
1815 <table border="0" bgcolor="#E0E0E0" width="90%">
1819 "SCREEN"> +filter{tiny-textforms} # Extend those tiny textareas up to 40x80 and kill the hard wrap.</pre>
1823 <p><a name="FILTER-JUMPING-WINDOWS" id="FILTER-JUMPING-WINDOWS"></a></p>
1824 <table border="0" bgcolor="#E0E0E0" width="90%">
1828 "SCREEN"> +filter{jumping-windows} # Prevent windows from resizing and moving themselves.</pre>
1832 <p><a name="FILTER-FRAMESET-BORDERS" id="FILTER-FRAMESET-BORDERS"></a></p>
1833 <table border="0" bgcolor="#E0E0E0" width="90%">
1837 "SCREEN"> +filter{frameset-borders} # Give frames a border and make them resizable.</pre>
1841 <p><a name="FILTER-IFRAMES" id="FILTER-IFRAMES"></a></p>
1842 <table border="0" bgcolor="#E0E0E0" width="90%">
1846 "SCREEN"> +filter{iframes} # Removes all detected iframes. Should only be enabled for individual sites.</pre>
1850 <p><a name="FILTER-DEMORONIZER" id="FILTER-DEMORONIZER"></a></p>
1851 <table border="0" bgcolor="#E0E0E0" width="90%">
1855 "SCREEN"> +filter{demoronizer} # Fix MS's non-standard use of standard charsets.</pre>
1859 <p><a name="FILTER-SHOCKWAVE-FLASH" id="FILTER-SHOCKWAVE-FLASH"></a></p>
1860 <table border="0" bgcolor="#E0E0E0" width="90%">
1863 <pre class="SCREEN"> +filter{shockwave-flash} # Kill embedded Shockwave Flash objects.</pre>
1867 <p><a name="FILTER-QUICKTIME-KIOSKMODE" id="FILTER-QUICKTIME-KIOSKMODE"></a></p>
1868 <table border="0" bgcolor="#E0E0E0" width="90%">
1871 <pre class="SCREEN"> +filter{quicktime-kioskmode} # Make Quicktime movies saveable.</pre>
1875 <p><a name="FILTER-FUN" id="FILTER-FUN"></a></p>
1876 <table border="0" bgcolor="#E0E0E0" width="90%">
1880 "SCREEN"> +filter{fun} # Text replacements for subversive browsing fun!</pre>
1884 <p><a name="FILTER-CRUDE-PARENTAL" id="FILTER-CRUDE-PARENTAL"></a></p>
1885 <table border="0" bgcolor="#E0E0E0" width="90%">
1889 "SCREEN"> +filter{crude-parental} # Crude parental filtering. Note that this filter doesn't work reliably.</pre>
1893 <p><a name="FILTER-IE-EXPLOITS" id="FILTER-IE-EXPLOITS"></a></p>
1894 <table border="0" bgcolor="#E0E0E0" width="90%">
1898 "SCREEN"> +filter{ie-exploits} # Disable some known Internet Explorer bug exploits.</pre>
1902 <p><a name="FILTER-SITE-SPECIFICS" id="FILTER-SITE-SPECIFICS"></a></p>
1903 <table border="0" bgcolor="#E0E0E0" width="90%">
1907 "SCREEN"> +filter{site-specifics} # Cure for site-specific problems. Don't apply generally!</pre>
1911 <p><a name="FILTER-NO-PING" id="FILTER-NO-PING"></a></p>
1912 <table border="0" bgcolor="#E0E0E0" width="90%">
1916 "SCREEN"> +filter{no-ping} # Removes non-standard ping attributes in <a> and <area> tags.</pre>
1920 <p><a name="FILTER-BUNDESWEHR.DE" id="FILTER-BUNDESWEHR.DE"></a></p>
1921 <table border="0" bgcolor="#E0E0E0" width="90%">
1925 "SCREEN"> +filter{bundeswehr.de} # Hide the cookie and privacy info banner on bundeswehr.de.</pre>
1929 <p><a name="FILTER-GITHUB" id="FILTER-GITHUB"></a></p>
1930 <table border="0" bgcolor="#E0E0E0" width="90%">
1934 "SCREEN"> +filter{github} # Removes the annoying "Sign-Up" banner and the Cookie disclaimer.</pre>
1938 <p><a name="FILTER-GOOGLE" id="FILTER-GOOGLE"></a></p>
1939 <table border="0" bgcolor="#E0E0E0" width="90%">
1943 "SCREEN"> +filter{google} # CSS-based block for Google text ads. Also removes a width limitation and the toolbar advertisement.</pre>
1947 <p><a name="FILTER-IMDB" id="FILTER-IMDB"></a></p>
1948 <table border="0" bgcolor="#E0E0E0" width="90%">
1951 <pre class="SCREEN"> +filter{imdb} # Removes some ads on IMDb.</pre>
1955 <p><a name="FILTER-YAHOO" id="FILTER-YAHOO"></a></p>
1956 <table border="0" bgcolor="#E0E0E0" width="90%">
1960 "SCREEN"> +filter{yahoo} # CSS-based block for Yahoo text ads. Also removes a width limitation.</pre>
1964 <p><a name="FILTER-MSN" id="FILTER-MSN"></a></p>
1965 <table border="0" bgcolor="#E0E0E0" width="90%">
1969 "SCREEN"> +filter{msn} # CSS-based block for MSN text ads. Also removes tracking URLs and a width limitation.</pre>
1973 <p><a name="FILTER-BLOGSPOT" id="FILTER-BLOGSPOT"></a></p>
1974 <table border="0" bgcolor="#E0E0E0" width="90%">
1978 "SCREEN"> +filter{blogspot} # Cleans up some Blogspot blogs. Read the fine print before using this.</pre>
1982 <p><a name="FILTER-SOURCEFORGE" id="FILTER-SOURCEFORGE"></a></p>
1983 <table border="0" bgcolor="#E0E0E0" width="90%">
1987 "SCREEN"> +filter{sourceforge} # Reduces the amount of ads for proprietary software on SourceForge.</pre>
1996 <h4 class="SECT3"><a name="FORCE-TEXT-MODE" id="FORCE-TEXT-MODE">8.5.20. force-text-mode</a></h4>
1997 <div class="VARIABLELIST">
1999 <dt>Typical use:</dt>
2001 <p>Force <span class="APPLICATION">Privoxy</span> to treat a document as if it was in some kind of
2002 <span class="emphasis"><i class="EMPHASIS">text</i></span> format.</p>
2006 <p>Declares a document as text, even if the <span class="QUOTE">"Content-Type:"</span> isn't detected as
2019 <p>As explained <tt class="LITERAL"><a href="actions-file.html#FILTER">above</a></tt>, <span class=
2020 "APPLICATION">Privoxy</span> tries to only filter files that are in some kind of text format. The same
2021 restrictions apply to <tt class="LITERAL"><a href=
2022 "actions-file.html#CONTENT-TYPE-OVERWRITE">content-type-overwrite</a></tt>. <tt class=
2023 "LITERAL">force-text-mode</tt> declares a document as text, without looking at the <span class=
2024 "QUOTE">"Content-Type:"</span> first.</p>
2025 <div class="WARNING">
2026 <table class="WARNING" border="1" width="90%">
2028 <td align="center"><b>Warning</b></td>
2032 <p>Think twice before activating this action. Filtering binary data with regular expressions can
2033 cause file damage.</p>
2039 <dt>Example usage:</dt>
2041 <table border="0" bgcolor="#E0E0E0" width="90%">
2044 <pre class="SCREEN"> +force-text-mode</pre>
2053 <h4 class="SECT3"><a name="FORWARD-OVERRIDE" id="FORWARD-OVERRIDE">8.5.21. forward-override</a></h4>
2054 <div class="VARIABLELIST">
2056 <dt>Typical use:</dt>
2058 <p>Change the forwarding settings based on User-Agent or request origin</p>
2062 <p>Overrules the forward directives in the configuration file.</p>
2066 <p>Parameterized.</p>
2072 <p><span class="QUOTE">"forward ."</span> to use a direct connection without any additional
2076 <p><span class="QUOTE">"forward 127.0.0.1:8123"</span> to use the HTTP proxy listening at 127.0.0.1
2080 <p><span class="QUOTE">"forward-socks4a 127.0.0.1:9050 ."</span> to use the socks4a proxy listening
2081 at 127.0.0.1 port 9050. Replace <span class="QUOTE">"forward-socks4a"</span> with <span class=
2082 "QUOTE">"forward-socks4"</span> to use a socks4 connection (with local DNS resolution) instead, use
2083 <span class="QUOTE">"forward-socks5"</span> for socks5 connections (with remote DNS resolution).</p>
2086 <p><span class="QUOTE">"forward-socks4a 127.0.0.1:9050 proxy.example.org:8000"</span> to use the
2087 socks4a proxy listening at 127.0.0.1 port 9050 to reach the HTTP proxy listening at proxy.example.org
2088 port 8000. Replace <span class="QUOTE">"forward-socks4a"</span> with <span class=
2089 "QUOTE">"forward-socks4"</span> to use a socks4 connection (with local DNS resolution) instead, use
2090 <span class="QUOTE">"forward-socks5"</span> for socks5 connections (with remote DNS resolution).</p>
2093 <p><span class="QUOTE">"forward-webserver 127.0.0.1:80"</span> to use the HTTP server listening at
2094 127.0.0.1 port 80 without adjusting the request headers.</p>
2095 <p>This makes it more convenient to use Privoxy to make existing websites available as onion services
2097 <p>Many websites serve content with hardcoded URLs and can't be easily adjusted to change the domain
2098 based on the one used by the client.</p>
2099 <p>Putting Privoxy between Tor and the webserver (or an stunnel that forwards to the webserver)
2100 allows to rewrite headers and content to make client and server happy at the same time.</p>
2101 <p>Using Privoxy for webservers that are only reachable through onion addresses and whose location is
2102 supposed to be secret is not recommended and should not be necessary anyway.</p>
2108 <p>This action takes parameters similar to the <a href="config.html#FORWARDING">forward</a> directives in
2109 the configuration file, but without the URL pattern. It can be used as replacement, but normally it's
2110 only used in cases where matching based on the request URL isn't sufficient.</p>
2111 <div class="WARNING">
2112 <table class="WARNING" border="1" width="90%">
2114 <td align="center"><b>Warning</b></td>
2118 <p>Please read the description for the <a href="config.html#FORWARDING">forward</a> directives
2119 before using this action. Forwarding to the wrong people will reduce your privacy and increase
2120 the chances of man-in-the-middle attacks.</p>
2121 <p>If the ports are missing or invalid, default values will be used. This might change in the
2122 future and you shouldn't rely on it. Otherwise incorrect syntax causes Privoxy to exit. Due to
2123 design limitations, invalid parameter syntax isn't detected until the action is used the first
2125 <p>Use the <a href="http://config.privoxy.org/show-url-info" target="_top">show-url-info CGI
2126 page</a> to verify that your forward settings do what you thought the do.</p>
2132 <dt>Example usage:</dt>
2134 <table border="0" bgcolor="#E0E0E0" width="90%">
2137 <pre class="SCREEN"> # Use an ssh tunnel for requests previously tagged as
2138 # <span class="QUOTE">"User-Agent: fetch libfetch/2.0"</span> and make sure
2139 # resuming downloads continues to work.
2141 # This way you can continue to use Tor for your normal browsing,
2142 # without overloading the Tor network with your FreeBSD ports updates
2143 # or downloads of bigger files like ISOs.
2145 # Note that HTTP headers are easy to fake and therefore their
2146 # values are as (un)trustworthy as your clients and users.
2147 {+forward-override{forward-socks5 10.0.0.2:2222 .} \
2148 -hide-if-modified-since \
2149 -overwrite-last-modified \
2151 TAG:^User-Agent: fetch libfetch/2\.0$</pre>
2160 <h4 class="SECT3"><a name="HANDLE-AS-EMPTY-DOCUMENT" id="HANDLE-AS-EMPTY-DOCUMENT">8.5.22.
2161 handle-as-empty-document</a></h4>
2162 <div class="VARIABLELIST">
2164 <dt>Typical use:</dt>
2166 <p>Mark URLs that should be replaced by empty documents <span class="emphasis"><i class="EMPHASIS">if
2167 they get blocked</i></span></p>
2171 <p>This action alone doesn't do anything noticeable. It just marks URLs. If the <tt class=
2172 "LITERAL"><a href="actions-file.html#BLOCK">block</a></tt> action <span class="emphasis"><i class=
2173 "EMPHASIS">also applies</i></span>, the presence or absence of this mark decides whether an HTML
2174 <span class="QUOTE">"BLOCKED"</span> page, or an empty document will be sent to the client as a
2175 substitute for the blocked content. The <span class="emphasis"><i class="EMPHASIS">empty</i></span>
2176 document isn't literally empty, but actually contains a single space.</p>
2188 <p>Some browsers complain about syntax errors if JavaScript documents are blocked with <span class=
2189 "APPLICATION">Privoxy's</span> default HTML page; this option can be used to silence them. And of course
2190 this action can also be used to eliminate the <span class="APPLICATION">Privoxy</span> BLOCKED message in
2192 <p>The content type for the empty document can be specified with <tt class="LITERAL"><a href=
2193 "actions-file.html#CONTENT-TYPE-OVERWRITE">content-type-overwrite{}</a></tt>, but usually this isn't
2196 <dt>Example usage:</dt>
2198 <table border="0" bgcolor="#E0E0E0" width="90%">
2201 <pre class="SCREEN"> # Block all documents on example.org that end with ".js",
2202 # but send an empty document instead of the usual HTML message.
2203 {+block{Blocked JavaScript} +handle-as-empty-document}
2204 example.org/.*\.js$</pre>
2213 <h4 class="SECT3"><a name="HANDLE-AS-IMAGE" id="HANDLE-AS-IMAGE">8.5.23. handle-as-image</a></h4>
2214 <div class="VARIABLELIST">
2216 <dt>Typical use:</dt>
2218 <p>Mark URLs as belonging to images (so they'll be replaced by images <span class="emphasis"><i class=
2219 "EMPHASIS">if they do get blocked</i></span>, rather than HTML pages)</p>
2223 <p>This action alone doesn't do anything noticeable. It just marks URLs as images. If the <tt class=
2224 "LITERAL"><a href="actions-file.html#BLOCK">block</a></tt> action <span class="emphasis"><i class=
2225 "EMPHASIS">also applies</i></span>, the presence or absence of this mark decides whether an HTML
2226 <span class="QUOTE">"blocked"</span> page, or a replacement image (as determined by the <tt class=
2227 "LITERAL"><a href="actions-file.html#SET-IMAGE-BLOCKER">set-image-blocker</a></tt> action) will be sent
2228 to the client as a substitute for the blocked content.</p>
2240 <p>The below generic example section is actually part of <tt class="FILENAME">default.action</tt>. It
2241 marks all URLs with well-known image file name extensions as images and should be left intact.</p>
2242 <p>Users will probably only want to use the handle-as-image action in conjunction with <tt class=
2243 "LITERAL"><a href="actions-file.html#BLOCK">block</a></tt>, to block sources of banners, whose URLs don't
2244 reflect the file type, like in the second example section.</p>
2245 <p>Note that you cannot treat HTML pages as images in most cases. For instance, (in-line) ad frames
2246 require an HTML page to be sent, or they won't display properly. Forcing <tt class=
2247 "LITERAL">handle-as-image</tt> in this situation will not replace the ad frame with an image, but lead to
2250 <dt>Example usage (sections):</dt>
2252 <table border="0" bgcolor="#E0E0E0" width="90%">
2255 <pre class="SCREEN"> # Generic image extensions:
2258 /.*\.(gif|jpg|jpeg|png|bmp|ico)$
2260 # These don't look like images, but they're banners and should be
2261 # blocked as images:
2263 {+block{Nasty banners.} +handle-as-image}
2264 nasty-banner-server.example.com/junk.cgi\?output=trash</pre>
2273 <h4 class="SECT3"><a name="HIDE-ACCEPT-LANGUAGE" id="HIDE-ACCEPT-LANGUAGE">8.5.24.
2274 hide-accept-language</a></h4>
2275 <div class="VARIABLELIST">
2277 <dt>Typical use:</dt>
2279 <p>Pretend to use different language settings.</p>
2283 <p>Deletes or replaces the <span class="QUOTE">"Accept-Language:"</span> HTTP header in client
2288 <p>Parameterized.</p>
2292 <p>Keyword: <span class="QUOTE">"block"</span>, or any user defined value.</p>
2296 <p>Faking the browser's language settings can be useful to make a foreign User-Agent set with <tt class=
2297 "LITERAL"><a href="actions-file.html#HIDE-USER-AGENT">hide-user-agent</a></tt> more believable.</p>
2298 <p>However some sites with content in different languages check the <span class=
2299 "QUOTE">"Accept-Language:"</span> to decide which one to take by default. Sometimes it isn't possible to
2300 later switch to another language without changing the <span class="QUOTE">"Accept-Language:"</span>
2302 <p>Therefore it's a good idea to either only change the <span class="QUOTE">"Accept-Language:"</span>
2303 header to languages you understand, or to languages that aren't wide spread.</p>
2304 <p>Before setting the <span class="QUOTE">"Accept-Language:"</span> header to a rare language, you should
2305 consider that it helps to make your requests unique and thus easier to trace. If you don't plan to change
2306 this header frequently, you should stick to a common language.</p>
2308 <dt>Example usage (section):</dt>
2310 <table border="0" bgcolor="#E0E0E0" width="90%">
2313 <pre class="SCREEN"> # Pretend to use Canadian language settings.
2314 {+hide-accept-language{en-ca} \
2315 +hide-user-agent{Mozilla/5.0 (X11; U; OpenBSD i386; en-CA; rv:1.8.0.4) Gecko/20060628 Firefox/1.5.0.4} \
2326 <h4 class="SECT3"><a name="HIDE-CONTENT-DISPOSITION" id="HIDE-CONTENT-DISPOSITION">8.5.25.
2327 hide-content-disposition</a></h4>
2328 <div class="VARIABLELIST">
2330 <dt>Typical use:</dt>
2332 <p>Prevent download menus for content you prefer to view inside the browser.</p>
2336 <p>Deletes or replaces the <span class="QUOTE">"Content-Disposition:"</span> HTTP header set by some
2341 <p>Parameterized.</p>
2345 <p>Keyword: <span class="QUOTE">"block"</span>, or any user defined value.</p>
2349 <p>Some servers set the <span class="QUOTE">"Content-Disposition:"</span> HTTP header for documents they
2350 assume you want to save locally before viewing them. The <span class=
2351 "QUOTE">"Content-Disposition:"</span> header contains the file name the browser is supposed to use by
2353 <p>In most browsers that understand this header, it makes it impossible to <span class=
2354 "emphasis"><i class="EMPHASIS">just view</i></span> the document, without downloading it first, even if
2355 it's just a simple text file or an image.</p>
2356 <p>Removing the <span class="QUOTE">"Content-Disposition:"</span> header helps to prevent this annoyance,
2357 but some browsers additionally check the <span class="QUOTE">"Content-Type:"</span> header, before they
2358 decide if they can display a document without saving it first. In these cases, you have to change this
2359 header as well, before the browser stops displaying download menus.</p>
2360 <p>It is also possible to change the server's file name suggestion to another one, but in most cases it
2361 isn't worth the time to set it up.</p>
2362 <p>This action will probably be removed in the future, use server-header filters instead.</p>
2364 <dt>Example usage:</dt>
2366 <table border="0" bgcolor="#E0E0E0" width="90%">
2369 <pre class="SCREEN"> # Disarm the download link in Sourceforge's patch tracker
2371 +content-type-overwrite{text/plain} \
2372 +hide-content-disposition{block} \
2374 .sourceforge.net/tracker/download\.php</pre>
2383 <h4 class="SECT3"><a name="HIDE-IF-MODIFIED-SINCE" id="HIDE-IF-MODIFIED-SINCE">8.5.26.
2384 hide-if-modified-since</a></h4>
2385 <div class="VARIABLELIST">
2387 <dt>Typical use:</dt>
2389 <p>Prevent yet another way to track the user's steps between sessions.</p>
2393 <p>Deletes the <span class="QUOTE">"If-Modified-Since:"</span> HTTP client header or modifies its
2398 <p>Parameterized.</p>
2402 <p>Keyword: <span class="QUOTE">"block"</span>, or a user defined value that specifies a range of
2407 <p>Removing this header is useful for filter testing, where you want to force a real reload instead of
2408 getting status code <span class="QUOTE">"304"</span>, which would cause the browser to use a cached copy
2410 <p>Instead of removing the header, <tt class="LITERAL">hide-if-modified-since</tt> can also add or
2411 subtract a random amount of time to/from the header's value. You specify a range of minutes where the
2412 random factor should be chosen from and <span class="APPLICATION">Privoxy</span> does the rest. A
2413 negative value means subtracting, a positive value adding.</p>
2414 <p>Randomizing the value of the <span class="QUOTE">"If-Modified-Since:"</span> makes it less likely that
2415 the server can use the time as a cookie replacement, but you will run into caching problems if the random
2416 range is too high.</p>
2417 <p>It is a good idea to only use a small negative value and let <tt class="LITERAL"><a href=
2418 "actions-file.html#OVERWRITE-LAST-MODIFIED">overwrite-last-modified</a></tt> handle the greater
2420 <p>It is also recommended to use this action together with <tt class="LITERAL"><a href=
2421 "actions-file.html#CRUNCH-IF-NONE-MATCH">crunch-if-none-match</a></tt>, otherwise it's more or less
2424 <dt>Example usage (section):</dt>
2426 <table border="0" bgcolor="#E0E0E0" width="90%">
2429 <pre class="SCREEN"> # Let the browser revalidate but make tracking based on the time less likely.
2430 {+hide-if-modified-since{-60} \
2431 +overwrite-last-modified{randomize} \
2432 +crunch-if-none-match}
2442 <h4 class="SECT3"><a name="HIDE-FROM-HEADER" id="HIDE-FROM-HEADER">8.5.27. hide-from-header</a></h4>
2443 <div class="VARIABLELIST">
2445 <dt>Typical use:</dt>
2447 <p>Keep your (old and ill) browser from telling web servers your email address</p>
2451 <p>Deletes any existing <span class="QUOTE">"From:"</span> HTTP header, or replaces it with the specified
2456 <p>Parameterized.</p>
2460 <p>Keyword: <span class="QUOTE">"block"</span>, or any user defined value.</p>
2464 <p>The keyword <span class="QUOTE">"block"</span> will completely remove the header (not to be confused
2465 with the <tt class="LITERAL"><a href="actions-file.html#BLOCK">block</a></tt> action).</p>
2466 <p>Alternately, you can specify any value you prefer to be sent to the web server. If you do, it is a
2467 matter of fairness not to use any address that is actually used by a real person.</p>
2468 <p>This action is rarely needed, as modern web browsers don't send <span class="QUOTE">"From:"</span>
2469 headers anymore.</p>
2471 <dt>Example usage:</dt>
2473 <table border="0" bgcolor="#E0E0E0" width="90%">
2476 <pre class="SCREEN"> +hide-from-header{block}</pre>
2481 <table border="0" bgcolor="#E0E0E0" width="90%">
2484 <pre class="SCREEN"> +hide-from-header{spam-me-senseless@sittingduck.example.com}</pre>
2493 <h4 class="SECT3"><a name="HIDE-REFERRER" id="HIDE-REFERRER">8.5.28. hide-referrer</a></h4><a name=
2494 "HIDE-REFERER" id="HIDE-REFERER"></a>
2495 <div class="VARIABLELIST">
2497 <dt>Typical use:</dt>
2499 <p>Conceal which link you followed to get to a particular site</p>
2503 <p>Deletes the <span class="QUOTE">"Referer:"</span> (sic) HTTP header from the client request, or
2504 replaces it with a forged one.</p>
2508 <p>Parameterized.</p>
2514 <p><span class="QUOTE">"conditional-block"</span> to delete the header completely if the host has
2518 <p><span class="QUOTE">"conditional-forge"</span> to forge the header if the host has changed.</p>
2521 <p><span class="QUOTE">"block"</span> to delete the header unconditionally.</p>
2524 <p><span class="QUOTE">"forge"</span> to pretend to be coming from the homepage of the server we are
2528 <p>Any other string to set a user defined referrer.</p>
2534 <p><tt class="LITERAL">conditional-block</tt> is the only parameter, that isn't easily detected in the
2535 server's log file. If it blocks the referrer, the request will look like the visitor used a bookmark or
2536 typed in the address directly.</p>
2537 <p>Leaving the referrer unmodified for requests on the same host allows the server owner to see the
2538 visitor's <span class="QUOTE">"click path"</span>, but in most cases she could also get that information
2539 by comparing other parts of the log file: for example the User-Agent if it isn't a very common one, or
2540 the user's IP address if it doesn't change between different requests.</p>
2541 <p>Always blocking the referrer, or using a custom one, can lead to failures on servers that check the
2542 referrer before they answer any requests, in an attempt to prevent their content from being embedded or
2543 linked to elsewhere.</p>
2544 <p>Both <tt class="LITERAL">conditional-block</tt> and <tt class="LITERAL">forge</tt> will work with
2545 referrer checks, as long as content and valid referring page are on the same host. Most of the time
2546 that's the case.</p>
2547 <p><tt class="LITERAL">hide-referer</tt> is an alternate spelling of <tt class=
2548 "LITERAL">hide-referrer</tt> and the two can be can be freely substituted with each other. (<span class=
2549 "QUOTE">"referrer"</span> is the correct English spelling, however the HTTP specification has a bug - it
2550 requires it to be spelled as <span class="QUOTE">"referer"</span>.)</p>
2552 <dt>Example usage:</dt>
2554 <table border="0" bgcolor="#E0E0E0" width="90%">
2557 <pre class="SCREEN"> +hide-referrer{forge}</pre>
2562 <table border="0" bgcolor="#E0E0E0" width="90%">
2565 <pre class="SCREEN"> +hide-referrer{http://www.yahoo.com/}</pre>
2574 <h4 class="SECT3"><a name="HIDE-USER-AGENT" id="HIDE-USER-AGENT">8.5.29. hide-user-agent</a></h4>
2575 <div class="VARIABLELIST">
2577 <dt>Typical use:</dt>
2579 <p>Try to conceal your type of browser and client operating system</p>
2583 <p>Replaces the value of the <span class="QUOTE">"User-Agent:"</span> HTTP header in client requests with
2584 the specified value.</p>
2588 <p>Parameterized.</p>
2592 <p>Any user-defined string.</p>
2596 <div class="WARNING">
2597 <table class="WARNING" border="1" width="90%">
2599 <td align="center"><b>Warning</b></td>
2603 <p>This can lead to problems on web sites that depend on looking at this header in order to
2604 customize their content for different browsers (which, by the way, is <span class=
2605 "emphasis"><i class="EMPHASIS">NOT</i></span> the right thing to do: good web sites work
2606 browser-independently).</p>
2611 <p>Using this action in multi-user setups or wherever different types of browsers will access the same
2612 <span class="APPLICATION">Privoxy</span> is <span class="emphasis"><i class="EMPHASIS">not
2613 recommended</i></span>. In single-user, single-browser setups, you might use it to delete your OS version
2614 information from the headers, because it is an invitation to exploit known bugs for your OS. It is also
2615 occasionally useful to forge this in order to access sites that won't let you in otherwise (though there
2616 may be a good reason in some cases).</p>
2617 <p>More information on known user-agent strings can be found at <a href="http://www.user-agents.org/"
2618 target="_top">http://www.user-agents.org/</a> and <a href="https://en.wikipedia.org/wiki/User_agent"
2619 target="_top">http://en.wikipedia.org/wiki/User_agent</a>.</p>
2621 <dt>Example usage:</dt>
2623 <table border="0" bgcolor="#E0E0E0" width="90%">
2627 "SCREEN"> +hide-user-agent{Mozilla/5.0 (X11; ElectroBSD i386; rv:78.0) Gecko/20100101 Firefox/78.0}</pre>
2636 <h4 class="SECT3"><a name="HTTPS-INSPECTION" id="HTTPS-INSPECTION">8.5.30. https-inspection</a></h4>
2637 <div class="VARIABLELIST">
2639 <dt>Typical use:</dt>
2641 <p>Filter encrypted requests and responses</p>
2645 <p>Encrypted requests are decrypted, filtered and forwarded encrypted.</p>
2657 <p>This action allows <span class="APPLICATION">Privoxy</span> to filter encrypted requests and
2658 responses. For this to work <span class="APPLICATION">Privoxy</span> has to generate a certificate for
2659 the web site and send it to the client which has to accept it.</p>
2660 <p>Before this works the directives in the <tt class="LITERAL"><a href=
2661 "config.html#HTTPS-INSPECTION-DIRECTIVES" target="_top">HTTPS inspection section</a></tt> of the config
2662 file have to be configured.</p>
2663 <p>Note that the action has to be enabled based on the CONNECT request which doesn't contain a path.
2664 Enabling it based on a pattern with path doesn't work as the path is only seen by <span class=
2665 "APPLICATION">Privoxy</span> if the action is already enabled.</p>
2667 <dt>Example usage (section):</dt>
2669 <table border="0" bgcolor="#E0E0E0" width="90%">
2672 <pre class="SCREEN"> {+https-inspection}
2673 www.example.com</pre>
2682 <h4 class="SECT3"><a name="IGNORE-CERTIFICATE-ERRORS" id="IGNORE-CERTIFICATE-ERRORS">8.5.31.
2683 ignore-certificate-errors</a></h4>
2684 <div class="VARIABLELIST">
2686 <dt>Typical use:</dt>
2688 <p>Filter encrypted requests and responses without verifying the certificate</p>
2692 <p>Encrypted requests are forwarded to sites without verifying the certificate.</p>
2704 <p>When the <a href="actions-file.html#HTTPS-INSPECTION"><span class=
2705 "QUOTE">"+https-inspection"</span></a> action is used <span class="APPLICATION">Privoxy</span> by default
2706 verifies that the remote site uses a valid certificate.</p>
2707 <p>If the certificate can't be validated by <span class="APPLICATION">Privoxy</span> the connection is
2709 <p>This action disables the certificate check so requests to sites with certificates that can't be
2710 validated are allowed.</p>
2711 <p>Note that enabling this action allows Man-in-the-middle attacks.</p>
2713 <dt>Example usage:</dt>
2715 <table border="0" bgcolor="#E0E0E0" width="90%">
2718 <pre class="SCREEN"> {+ignore-certificate-errors}
2719 www.example.org</pre>
2728 <h4 class="SECT3"><a name="LIMIT-CONNECT" id="LIMIT-CONNECT">8.5.32. limit-connect</a></h4>
2729 <div class="VARIABLELIST">
2731 <dt>Typical use:</dt>
2733 <p>Prevent abuse of <span class="APPLICATION">Privoxy</span> as a TCP proxy relay or disable SSL for
2738 <p>Specifies to which ports HTTP CONNECT requests are allowable.</p>
2742 <p>Parameterized.</p>
2746 <p>A comma-separated list of ports or port ranges (the latter using dashes, with the minimum defaulting
2747 to 0 and the maximum to 65K).</p>
2751 <p>By default, i.e. if no <tt class="LITERAL">limit-connect</tt> action applies, <span class=
2752 "APPLICATION">Privoxy</span> allows HTTP CONNECT requests to all ports. Use <tt class=
2753 "LITERAL">limit-connect</tt> if fine-grained control is desired for some or all destinations.</p>
2754 <p>The CONNECT methods exists in HTTP to allow access to secure websites (<span class=
2755 "QUOTE">"https://"</span> URLs) through proxies. It works very simply: the proxy connects to the server
2756 on the specified port, and then short-circuits its connections to the client and to the remote server.
2757 This means CONNECT-enabled proxies can be used as TCP relays very easily.</p>
2758 <p><span class="APPLICATION">Privoxy</span> relays HTTPS traffic without seeing the decoded content.
2759 Websites can leverage this limitation to circumvent <span class="APPLICATION">Privoxy</span>'s filters.
2760 By specifying an invalid port range you can disable HTTPS entirely.</p>
2762 <dt>Example usages:</dt>
2764 <table border="0" bgcolor="#E0E0E0" width="90%">
2767 <pre class="SCREEN"> +limit-connect{443} # Port 443 is OK.
2768 +limit-connect{80,443} # Ports 80 and 443 are OK.
2769 +limit-connect{-3, 7, 20-100, 500-} # Ports less than 3, 7, 20 to 100 and above 500 are OK.
2770 +limit-connect{-} # All ports are OK
2771 +limit-connect{,} # No HTTPS/SSL traffic is allowed</pre>
2780 <h4 class="SECT3"><a name="LIMIT-COOKIE-LIFETIME" id="LIMIT-COOKIE-LIFETIME">8.5.33.
2781 limit-cookie-lifetime</a></h4>
2782 <div class="VARIABLELIST">
2784 <dt>Typical use:</dt>
2786 <p>Limit the lifetime of HTTP cookies to a couple of minutes or hours.</p>
2790 <p>Overwrites the expires field in Set-Cookie server headers if it's above the specified limit.</p>
2794 <p>Parameterized.</p>
2798 <p>The lifetime limit in minutes, or 0.</p>
2802 <p>This action reduces the lifetime of HTTP cookies coming from the server to the specified number of
2803 minutes, starting from the time the cookie passes Privoxy.</p>
2804 <p>Cookies with a lifetime below the limit are not modified. The lifetime of session cookies is set to
2805 the specified limit.</p>
2806 <p>The effect of this action depends on the server.</p>
2807 <p>In case of servers which refresh their cookies with each response (or at least frequently), the
2808 lifetime limit set by this action is updated as well. Thus, a session associated with the cookie
2809 continues to work with this action enabled, as long as a new request is made before the last limit set is
2811 <p>However, some servers send their cookies once, with a lifetime of several years (the year 2037 is a
2812 popular choice), and do not refresh them until a certain event in the future, for example the user
2813 logging out. In this case this action may limit the absolute lifetime of the session, even if requests
2814 are made frequently.</p>
2815 <p>If the parameter is <span class="QUOTE">"0"</span>, this action behaves like <tt class=
2816 "LITERAL"><a href="actions-file.html#SESSION-COOKIES-ONLY">session-cookies-only</a></tt>.</p>
2818 <dt>Example usages:</dt>
2820 <table border="0" bgcolor="#E0E0E0" width="90%">
2823 <pre class="SCREEN"> +limit-cookie-lifetime{60}</pre>
2832 <h4 class="SECT3"><a name="PREVENT-COMPRESSION" id="PREVENT-COMPRESSION">8.5.34. prevent-compression</a></h4>
2833 <div class="VARIABLELIST">
2835 <dt>Typical use:</dt>
2837 <p>Ensure that servers send the content uncompressed, so it can be passed through <tt class=
2838 "LITERAL"><a href="actions-file.html#FILTER">filter</a></tt>s.</p>
2842 <p>Removes the Accept-Encoding header which can be used to ask for compressed transfer.</p>
2854 <p>More and more websites send their content compressed by default, which is generally a good idea and
2855 saves bandwidth. But the <tt class="LITERAL"><a href="actions-file.html#FILTER">filter</a></tt> and
2856 <tt class="LITERAL"><a href="actions-file.html#DEANIMATE-GIFS">deanimate-gifs</a></tt> actions need
2857 access to the uncompressed data.</p>
2858 <p>When compiled with zlib support (available since <span class="APPLICATION">Privoxy</span> 3.0.7),
2859 content that should be filtered is decompressed on-the-fly and you don't have to worry about this action.
2860 If you are using an older <span class="APPLICATION">Privoxy</span> version, or one that hasn't been
2861 compiled with zlib support, this action can be used to convince the server to send the content
2863 <p>Most text-based instances compress very well, the size is seldom decreased by less than 50%, for
2864 markup-heavy instances like news feeds saving more than 90% of the original size isn't unusual.</p>
2865 <p>Not using compression will therefore slow down the transfer, and you should only enable this action if
2866 you really need it. As of <span class="APPLICATION">Privoxy</span> 3.0.7 it's disabled in all predefined
2867 action settings.</p>
2868 <p>Note that some (rare) ill-configured sites don't handle requests for uncompressed documents correctly.
2869 Broken PHP applications tend to send an empty document body, some IIS versions only send the beginning of
2870 the content and some content delivery networks let the connection time out. If you enable <tt class=
2871 "LITERAL">prevent-compression</tt> per default, you might want to add exceptions for those sites. See the
2872 example for how to do that.</p>
2874 <dt>Example usage (sections):</dt>
2876 <table border="0" bgcolor="#E0E0E0" width="90%">
2879 <pre class="SCREEN"> # Selectively turn off compression, and enable a filter
2881 { +filter{tiny-textforms} +prevent-compression }
2882 # Match only these sites
2887 # Or instead, we could set a universal default:
2889 { +prevent-compression }
2892 # Then maybe make exceptions for broken sites:
2894 { -prevent-compression }
2904 <h4 class="SECT3"><a name="OVERWRITE-LAST-MODIFIED" id="OVERWRITE-LAST-MODIFIED">8.5.35.
2905 overwrite-last-modified</a></h4>
2906 <div class="VARIABLELIST">
2908 <dt>Typical use:</dt>
2910 <p>Prevent yet another way to track the user's steps between sessions.</p>
2914 <p>Deletes the <span class="QUOTE">"Last-Modified:"</span> HTTP server header or modifies its value.</p>
2918 <p>Parameterized.</p>
2922 <p>One of the keywords: <span class="QUOTE">"block"</span>, <span class=
2923 "QUOTE">"reset-to-request-time"</span> and <span class="QUOTE">"randomize"</span></p>
2927 <p>Removing the <span class="QUOTE">"Last-Modified:"</span> header is useful for filter testing, where
2928 you want to force a real reload instead of getting status code <span class="QUOTE">"304"</span>, which
2929 would cause the browser to reuse the old version of the page.</p>
2930 <p>The <span class="QUOTE">"randomize"</span> option overwrites the value of the <span class=
2931 "QUOTE">"Last-Modified:"</span> header with a randomly chosen time between the original value and the
2932 current time. In theory the server could send each document with a different <span class=
2933 "QUOTE">"Last-Modified:"</span> header to track visits without using cookies. <span class=
2934 "QUOTE">"Randomize"</span> makes it impossible and the browser can still revalidate cached documents.</p>
2935 <p><span class="QUOTE">"reset-to-request-time"</span> overwrites the value of the <span class=
2936 "QUOTE">"Last-Modified:"</span> header with the current time. You could use this option together with
2937 <tt class="LITERAL"><a href="actions-file.html#HIDE-IF-MODIFIED-SINCE">hide-if-modified-since</a></tt> to
2938 further customize your random range.</p>
2939 <p>The preferred parameter here is <span class="QUOTE">"randomize"</span>. It is safe to use, as long as
2940 the time settings are more or less correct. If the server sets the <span class=
2941 "QUOTE">"Last-Modified:"</span> header to the time of the request, the random range becomes zero and the
2942 value stays the same. Therefore you should later randomize it a second time with <tt class=
2943 "LITERAL"><a href="actions-file.html#HIDE-IF-MODIFIED-SINCE">hided-if-modified-since</a></tt>, just to be
2945 <p>It is also recommended to use this action together with <tt class="LITERAL"><a href=
2946 "actions-file.html#CRUNCH-IF-NONE-MATCH">crunch-if-none-match</a></tt>.</p>
2948 <dt>Example usage:</dt>
2950 <table border="0" bgcolor="#E0E0E0" width="90%">
2953 <pre class="SCREEN"> # Let the browser revalidate without being tracked across sessions
2954 { +hide-if-modified-since{-60} \
2955 +overwrite-last-modified{randomize} \
2956 +crunch-if-none-match \
2967 <h4 class="SECT3"><a name="REDIRECT" id="REDIRECT">8.5.36. redirect</a></h4>
2968 <div class="VARIABLELIST">
2970 <dt>Typical use:</dt>
2972 <p>Redirect requests to other sites.</p>
2976 <p>Convinces the browser that the requested document has been moved to another location and the browser
2977 should get it from there.</p>
2981 <p>Parameterized</p>
2985 <p>An absolute URL or a single pcrs command.</p>
2989 <p>Requests to which this action applies are answered with a HTTP redirect to URLs of your choosing. The
2990 new URL is either provided as parameter, or derived by applying a single pcrs command to the original
2992 <p>The syntax for pcrs commands is documented in the <a href="filter-file.html">filter file</a>
2994 <p>Requests can't be blocked and redirected at the same time, applying this action together with
2995 <tt class="LITERAL"><a href="actions-file.html#BLOCK">block</a></tt> is a configuration error. Currently
2996 the request is blocked and an error message logged, the behavior may change in the future and result in
2997 Privoxy rejecting the action file.</p>
2998 <p>This action can be combined with <tt class="LITERAL"><a href=
2999 "actions-file.html#FAST-REDIRECTS">fast-redirects{check-decoded-url}</a></tt> to redirect to a decoded
3000 version of a rewritten URL.</p>
3001 <p>Use this action carefully, make sure not to create redirection loops and be aware that using your own
3002 redirects might make it possible to fingerprint your requests.</p>
3003 <p>In case of problems with your redirects, or simply to watch them working, enable <a href=
3004 "config.html#DEBUG">debug 128</a>.</p>
3006 <dt>Example usages:</dt>
3008 <table border="0" bgcolor="#E0E0E0" width="90%">
3011 <pre class="SCREEN"> # Replace example.com's style sheet with another one
3012 { +redirect{http://localhost/css-replacements/example.com.css} }
3013 example.com/stylesheet\.css
3015 # Create a short, easy to remember nickname for a favorite site
3016 # (relies on the browser to accept and forward invalid URLs to <span class="APPLICATION">Privoxy</span>)
3017 { +redirect{https://www.privoxy.org/user-manual/actions-file.html} }
3020 # Always use the expanded view for Undeadly.org articles
3021 # (Note the $ at the end of the URL pattern to make sure
3022 # the request for the rewritten URL isn't redirected as well)
3023 {+redirect{s@$@&mode=expanded@}}
3024 undeadly.org/cgi\?action=article&sid=\d*$
3026 # Redirect Google search requests to MSN
3027 {+redirect{s@^http://[^/]*/search\?q=([^&]*).*@http://search.msn.com/results.aspx?q=$1@}}
3030 # Redirect MSN search requests to Yahoo
3031 {+redirect{s@^http://[^/]*/results\.aspx\?q=([^&]*).*@http://search.yahoo.com/search?p=$1@}}
3032 search.msn.com//results\.aspx\?q=
3034 # Redirect http://example.com/&bla=fasel&toChange=foo (and any other value but "bar")
3035 # to http://example.com/&bla=fasel&toChange=bar
3037 # The URL pattern makes sure that the following request isn't redirected again.
3038 {+redirect{s@toChange=[^&]+@toChange=bar@}}
3039 example.com/.*toChange=(?!bar)
3041 # Add a shortcut to look up illumos bugs
3042 {+redirect{s@^http://i([0-9]+)/.*@https://www.illumos.org/issues/$1@}}
3043 # Redirected URL = http://i4974/
3044 # Redirect Destination = https://www.illumos.org/issues/4974
3045 i[0-9][0-9][0-9][0-9]*/
3047 # Redirect requests for the old Tor Hidden Service of the Privoxy website to the new one
3048 {+redirect{s@^http://jvauzb4sb3bwlsnc.onion/@http://l3tczdiiwoo63iwxty4lhs6p7eaxop5micbn7vbliydgv63x5zrrrfyd.onion/@}}
3049 jvauzb4sb3bwlsnc.onion/
3051 # Redirect remote requests for this manual
3052 # to the local version delivered by Privoxy
3053 {+redirect{s@^http://www@http://config@}}
3054 www.privoxy.org/user-manual/</pre>
3063 <h4 class="SECT3"><a name="SERVER-HEADER-FILTER" id="SERVER-HEADER-FILTER">8.5.37.
3064 server-header-filter</a></h4>
3065 <div class="VARIABLELIST">
3067 <dt>Typical use:</dt>
3069 <p>Rewrite or remove single server headers.</p>
3073 <p>All server headers to which this action applies are filtered on-the-fly through the specified regular
3074 expression based substitutions.</p>
3082 <p>The name of a server-header filter, as defined in one of the <a href="filter-file.html">filter
3087 <p>Server-header filters are applied to each header on its own, not to all at once. This makes it easier
3088 to diagnose problems, but on the downside you can't write filters that only change header x if header y's
3089 value is z. You can do that by using tags though.</p>
3090 <p>Server-header filters are executed after the other header actions have finished and use their output
3092 <p>Please refer to the <a href="filter-file.html">filter file chapter</a> to learn which server-header
3093 filters are available by default, and how to create your own.</p>
3095 <dt>Example usage (section):</dt>
3097 <table border="0" bgcolor="#E0E0E0" width="90%">
3100 <pre class="SCREEN"> {+server-header-filter{html-to-xml}}
3101 example.org/xml-instance-that-is-delivered-as-html
3103 {+server-header-filter{xml-to-html}}
3104 example.org/instance-that-is-delivered-as-xml-but-is-not</pre>
3113 <h4 class="SECT3"><a name="SERVER-HEADER-TAGGER" id="SERVER-HEADER-TAGGER">8.5.38.
3114 server-header-tagger</a></h4>
3115 <div class="VARIABLELIST">
3117 <dt>Typical use:</dt>
3119 <p>Enable or disable filters based on the Content-Type header.</p>
3123 <p>Server headers to which this action applies are filtered on-the-fly through the specified regular
3124 expression based substitutions, the result is used as tag.</p>
3132 <p>The name of a server-header tagger, as defined in one of the <a href="filter-file.html">filter
3137 <p>Server-header taggers are applied to each header on its own, and as the header isn't modified, each
3138 tagger <span class="QUOTE">"sees"</span> the original.</p>
3139 <p>Server-header taggers are executed before all other header actions that modify server headers. Their
3140 tags can be used to control all of the other server-header actions, the content filters and the crunch
3141 actions (<a href="actions-file.html#REDIRECT">redirect</a> and <a href=
3142 "actions-file.html#BLOCK">block</a>).</p>
3143 <p>Obviously crunching based on tags created by server-header taggers doesn't prevent the request from
3144 showing up in the server's log file.</p>
3146 <dt>Example usage (section):</dt>
3148 <table border="0" bgcolor="#E0E0E0" width="90%">
3151 <pre class="SCREEN"> # Tag every request with the content type declared by the server
3152 {+server-header-tagger{content-type}}
3155 # If the response has a tag starting with 'image/' enable an external
3156 # filter that only applies to images.
3158 # Note that the filter is not available by default, it's just a
3159 # <tt class="LITERAL"><a href="filter-file.html#EXTERNAL-FILTER-SYNTAX">silly example</a></tt>.
3160 {+external-filter{rotate-image} +force-text-mode}
3170 <h4 class="SECT3"><a name="SUPPRESS-TAG" id="SUPPRESS-TAG">8.5.39. suppress-tag</a></h4>
3171 <div class="VARIABLELIST">
3173 <dt>Typical use:</dt>
3175 <p>Suppress client or server tag.</p>
3179 <p>Server or client tags to which this action applies are not added to the request, thus making all
3180 actions that are specific to these request tags inactive.</p>
3188 <p>The result tag of a server-header or client-header tagger, as defined in one of the <a href=
3189 "filter-file.html">filter files</a>.</p>
3191 <dt>Example usage (section):</dt>
3193 <table border="0" bgcolor="#E0E0E0" width="90%">
3197 "SCREEN"> # Suppress tag produced by range-requests client-header tagger for requests coming from address 10.0.0.1
3198 {+suppress-tag{RANGE-REQUEST}}
3199 TAG:^IP-ADDRESS: 10\.0\.0\.1$</pre>
3208 <h4 class="SECT3"><a name="SESSION-COOKIES-ONLY" id="SESSION-COOKIES-ONLY">8.5.40.
3209 session-cookies-only</a></h4>
3210 <div class="VARIABLELIST">
3212 <dt>Typical use:</dt>
3214 <p>Allow only temporary <span class="QUOTE">"session"</span> cookies (for the current browser session
3215 <span class="emphasis"><i class="EMPHASIS">only</i></span>).</p>
3219 <p>Deletes the <span class="QUOTE">"expires"</span> field from <span class="QUOTE">"Set-Cookie:"</span>
3220 server headers. Most browsers will not store such cookies permanently and forget them in between
3233 <p>This is less strict than <tt class="LITERAL"><a href=
3234 "actions-file.html#CRUNCH-INCOMING-COOKIES">crunch-incoming-cookies</a></tt> / <tt class=
3235 "LITERAL"><a href="actions-file.html#CRUNCH-OUTGOING-COOKIES">crunch-outgoing-cookies</a></tt> and allows
3236 you to browse websites that insist or rely on setting cookies, without compromising your privacy too
3238 <p>Most browsers will not permanently store cookies that have been processed by <tt class=
3239 "LITERAL">session-cookies-only</tt> and will forget about them between sessions. This makes profiling
3240 cookies useless, but won't break sites which require cookies so that you can log in for transactions.
3241 This is generally turned on for all sites, and is the recommended setting.</p>
3242 <p>It makes <span class="emphasis"><i class="EMPHASIS">no sense at all</i></span> to use <tt class=
3243 "LITERAL">session-cookies-only</tt> together with <tt class="LITERAL"><a href=
3244 "actions-file.html#CRUNCH-INCOMING-COOKIES">crunch-incoming-cookies</a></tt> or <tt class=
3245 "LITERAL"><a href="actions-file.html#CRUNCH-OUTGOING-COOKIES">crunch-outgoing-cookies</a></tt>. If you
3246 do, cookies will be plainly killed.</p>
3247 <p>Note that it is up to the browser how it handles such cookies without an <span class=
3248 "QUOTE">"expires"</span> field. If you use an exotic browser, you might want to try it out to be
3250 <p>This setting also has no effect on cookies that may have been stored previously by the browser before
3251 starting <span class="APPLICATION">Privoxy</span>. These would have to be removed manually.</p>
3252 <p><span class="APPLICATION">Privoxy</span> also uses the <a href=
3253 "actions-file.html#FILTER-CONTENT-COOKIES">content-cookies filter</a> to block some types of cookies.
3254 Content cookies are not effected by <tt class="LITERAL">session-cookies-only</tt>.</p>
3256 <dt>Example usage:</dt>
3258 <table border="0" bgcolor="#E0E0E0" width="90%">
3261 <pre class="SCREEN"> +session-cookies-only</pre>
3270 <h4 class="SECT3"><a name="SET-IMAGE-BLOCKER" id="SET-IMAGE-BLOCKER">8.5.41. set-image-blocker</a></h4>
3271 <div class="VARIABLELIST">
3273 <dt>Typical use:</dt>
3275 <p>Choose the replacement for blocked images</p>
3279 <p>This action alone doesn't do anything noticeable. If <span class="emphasis"><i class=
3280 "EMPHASIS">both</i></span> <tt class="LITERAL"><a href="actions-file.html#BLOCK">block</a></tt>
3281 <span class="emphasis"><i class="EMPHASIS">and</i></span> <tt class="LITERAL"><a href=
3282 "actions-file.html#HANDLE-AS-IMAGE">handle-as-image</a></tt> <span class="emphasis"><i class=
3283 "EMPHASIS">also</i></span> apply, i.e. if the request is to be blocked as an image, <span class=
3284 "emphasis"><i class="EMPHASIS">then</i></span> the parameter of this action decides what will be sent as
3289 <p>Parameterized.</p>
3295 <p><span class="QUOTE">"pattern"</span> to send a built-in checkerboard pattern image. The image is
3296 visually decent, scales very well, and makes it obvious where banners were busted.</p>
3299 <p><span class="QUOTE">"blank"</span> to send a built-in transparent image. This makes banners
3300 disappear completely, but makes it hard to detect where <span class="APPLICATION">Privoxy</span> has
3301 blocked images on a given page and complicates troubleshooting if <span class=
3302 "APPLICATION">Privoxy</span> has blocked innocent images, like navigation icons.</p>
3305 <p><span class="QUOTE">"<tt class="REPLACEABLE"><i>target-url</i></tt>"</span> to send a redirect to
3306 <tt class="REPLACEABLE"><i>target-url</i></tt>. You can redirect to any image anywhere, even in your
3307 local filesystem via <span class="QUOTE">"file:///"</span> URL. (But note that not all browsers
3308 support redirecting to a local file system).</p>
3309 <p>A good application of redirects is to use special <span class=
3310 "APPLICATION">Privoxy</span>-built-in URLs, which send the built-in images, as <tt class=
3311 "REPLACEABLE"><i>target-url</i></tt>. This has the same visual effect as specifying <span class=
3312 "QUOTE">"blank"</span> or <span class="QUOTE">"pattern"</span> in the first place, but enables your
3313 browser to cache the replacement image, instead of requesting it over and over again.</p>
3319 <p>The URLs for the built-in images are <span class=
3320 "QUOTE">"http://config.privoxy.org/send-banner?type=<tt class="REPLACEABLE"><i>type</i></tt>"</span>,
3321 where <tt class="REPLACEABLE"><i>type</i></tt> is either <span class="QUOTE">"blank"</span> or
3322 <span class="QUOTE">"pattern"</span>.</p>
3323 <p>There is a third (advanced) type, called <span class="QUOTE">"auto"</span>. It is <span class=
3324 "emphasis"><i class="EMPHASIS">NOT</i></span> to be used in <tt class="LITERAL">set-image-blocker</tt>,
3325 but meant for use from <a href="filter-file.html">filters</a>. Auto will select the type of image that
3326 would have applied to the referring page, had it been an image.</p>
3328 <dt>Example usage:</dt>
3330 <p>Built-in pattern:</p>
3331 <table border="0" bgcolor="#E0E0E0" width="90%">
3334 <pre class="SCREEN"> +set-image-blocker{pattern}</pre>
3338 <p>Redirect to the BSD daemon:</p>
3339 <table border="0" bgcolor="#E0E0E0" width="90%">
3342 <pre class="SCREEN"> +set-image-blocker{http://www.freebsd.org/gifs/dae_up3.gif}</pre>
3346 <p>Redirect to the built-in pattern for better caching:</p>
3347 <table border="0" bgcolor="#E0E0E0" width="90%">
3350 <pre class="SCREEN"> +set-image-blocker{http://config.privoxy.org/send-banner?type=pattern}</pre>
3359 <h3 class="SECT3"><a name="SUMMARY" id="SUMMARY">8.5.42. Summary</a></h3>
3360 <p>Note that many of these actions have the potential to cause a page to misbehave, possibly even not to
3361 display at all. There are many ways a site designer may choose to design his site, and what HTTP header
3362 content, and other criteria, he may depend on. There is no way to have hard and fast rules for all sites. See
3363 the <a href="appendix.html#ACTIONSANAT">Appendix</a> for a brief example on troubleshooting actions.</p>
3367 <h2 class="SECT2"><a name="ALIASES" id="ALIASES">8.6. Aliases</a></h2>
3368 <p>Custom <span class="QUOTE">"actions"</span>, known to <span class="APPLICATION">Privoxy</span> as <span class=
3369 "QUOTE">"aliases"</span>, can be defined by combining other actions. These can in turn be invoked just like the
3370 built-in actions. Currently, an alias name can contain any character except space, tab, <span class=
3371 "QUOTE">"="</span>, <span class="QUOTE">"{"</span> and <span class="QUOTE">"}"</span>, but we <span class=
3372 "emphasis"><i class="EMPHASIS">strongly recommend</i></span> that you only use <span class="QUOTE">"a"</span> to
3373 <span class="QUOTE">"z"</span>, <span class="QUOTE">"0"</span> to <span class="QUOTE">"9"</span>, <span class=
3374 "QUOTE">"+"</span>, and <span class="QUOTE">"-"</span>. Alias names are not case sensitive, and are not required
3375 to start with a <span class="QUOTE">"+"</span> or <span class="QUOTE">"-"</span> sign, since they are merely
3376 textually expanded.</p>
3377 <p>Aliases can be used throughout the actions file, but they <span class="emphasis"><i class="EMPHASIS">must be
3378 defined in a special section at the top of the file!</i></span> And there can only be one such section per
3379 actions file. Each actions file may have its own alias section, and the aliases defined in it are only visible
3380 within that file.</p>
3381 <p>There are two main reasons to use aliases: One is to save typing for frequently used combinations of actions,
3382 the other one is a gain in flexibility: If you decide once how you want to handle shops by defining an alias
3383 called <span class="QUOTE">"shop"</span>, you can later change your policy on shops in <span class=
3384 "emphasis"><i class="EMPHASIS">one</i></span> place, and your changes will take effect everywhere in the actions
3385 file where the <span class="QUOTE">"shop"</span> alias is used. Calling aliases by their purpose also makes your
3386 actions files more readable.</p>
3387 <p>Currently, there is one big drawback to using aliases, though: <span class="APPLICATION">Privoxy</span>'s
3388 built-in web-based action file editor honors aliases when reading the actions files, but it expands them before
3389 writing. So the effects of your aliases are of course preserved, but the aliases themselves are lost when you
3390 edit sections that use aliases with it.</p>
3391 <p>Now let's define some aliases...</p>
3392 <table border="0" bgcolor="#E0E0E0" width="100%">
3395 <pre class="SCREEN"> # Useful custom aliases we can use later.
3397 # Note the (required!) section header line and that this section
3398 # must be at the top of the actions file!
3402 # These aliases just save typing later:
3403 # (Note that some already use other aliases!)
3405 +crunch-all-cookies = +<a href="actions-file.html#CRUNCH-INCOMING-COOKIES">crunch-incoming-cookies</a> +<a href=
3406 "actions-file.html#CRUNCH-OUTGOING-COOKIES">crunch-outgoing-cookies</a>
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 +block-as-image = +block{Blocked image.} +handle-as-image
3410 allow-all-cookies = -crunch-all-cookies -<a href=
3411 "actions-file.html#SESSION-COOKIES-ONLY">session-cookies-only</a> -<a href=
3412 "actions-file.html#FILTER-CONTENT-COOKIES">filter{content-cookies}</a>
3414 # These aliases define combinations of actions
3415 # that are useful for certain types of sites:
3417 fragile = -<a href="actions-file.html#BLOCK">block</a> -<a href=
3418 "actions-file.html#FILTER">filter</a> -crunch-all-cookies -<a href=
3419 "actions-file.html#FAST-REDIRECTS">fast-redirects</a> -<a href=
3420 "actions-file.html#HIDE-REFERER">hide-referrer</a> -<a href=
3421 "actions-file.html#PREVENT-COMPRESSION">prevent-compression</a>
3423 shop = -crunch-all-cookies -<a href="actions-file.html#FILTER-ALL-POPUPS">filter{all-popups}</a>
3425 # Short names for other aliases, for really lazy people ;-)
3427 c0 = +crunch-all-cookies
3428 c1 = -crunch-all-cookies</pre>
3432 <p>...and put them to use. These sections would appear in the lower part of an actions file and define exceptions
3433 to the default actions (as specified further up for the <span class="QUOTE">"/"</span> pattern):</p>
3434 <table border="0" bgcolor="#E0E0E0" width="100%">
3437 <pre class="SCREEN"> # These sites are either very complex or very keen on
3438 # user data and require minimal interference to work:
3441 .office.microsoft.com
3442 .windowsupdate.microsoft.com
3443 # Gmail is really mail.google.com, not gmail.com
3447 # Allow cookies (for setting and retrieving your customer data)
3451 .worldpay.com # for quietpc.com
3454 # These shops require pop-ups:
3456 {-filter{all-popups} -filter{unsolicited-popups}}
3458 .overclockers.co.uk</pre>
3462 <p>Aliases like <span class="QUOTE">"shop"</span> and <span class="QUOTE">"fragile"</span> are typically used for
3463 <span class="QUOTE">"problem"</span> sites that require more than one action to be disabled in order to function
3467 <h2 class="SECT2"><a name="ACT-EXAMPLES" id="ACT-EXAMPLES">8.7. Actions Files Tutorial</a></h2>
3468 <p>The above chapters have shown <a href="actions-file.html">which actions files there are and how they are
3469 organized</a>, how actions are <a href="actions-file.html#ACTIONS">specified</a> and <a href=
3470 "actions-file.html#ACTIONS-APPLY">applied to URLs</a>, how <a href="actions-file.html#AF-PATTERNS">patterns</a>
3471 work, and how to define and use <a href="actions-file.html#ALIASES">aliases</a>. Now, let's look at an example
3472 <tt class="FILENAME">match-all.action</tt>, <tt class="FILENAME">default.action</tt> and <tt class=
3473 "FILENAME">user.action</tt> file and see how all these pieces come together:</p>
3475 <h3 class="SECT3"><a name="MATCH-ALL" id="MATCH-ALL">8.7.1. match-all.action</a></h3>
3476 <p>Remember <span class="emphasis"><i class="EMPHASIS">all actions are disabled when matching
3477 starts</i></span>, so we have to explicitly enable the ones we want.</p>
3478 <p>While the <tt class="FILENAME">match-all.action</tt> file only contains a single section, it is probably the
3479 most important one. It has only one pattern, <span class="QUOTE">"<tt class="LITERAL">/</tt>"</span>, but this
3480 pattern <a href="actions-file.html#AF-PATTERNS">matches all URLs</a>. Therefore, the set of actions used in
3481 this <span class="QUOTE">"default"</span> section <span class="emphasis"><i class="EMPHASIS">will be applied to
3482 all requests as a start</i></span>. It can be partly or wholly overridden by other actions files like
3483 <tt class="FILENAME">default.action</tt> and <tt class="FILENAME">user.action</tt>, but it will still be
3484 largely responsible for your overall browsing experience.</p>
3485 <p>Again, at the start of matching, all actions are disabled, so there is no need to disable any actions here.
3486 (Remember: a <span class="QUOTE">"+"</span> preceding the action name enables the action, a <span class=
3487 "QUOTE">"-"</span> disables!). Also note how this long line has been made more readable by splitting it into
3488 multiple lines with line continuation.</p>
3489 <table border="0" bgcolor="#E0E0E0" width="100%">
3492 <pre class="SCREEN"> { \
3493 +<a href="actions-file.html#CHANGE-X-FORWARDED-FOR">change-x-forwarded-for{block}</a> \
3494 +<a href="actions-file.html#HIDE-FROM-HEADER">hide-from-header{block}</a> \
3495 +<a href="actions-file.html#SET-IMAGE-BLOCKER">set-image-blocker{pattern}</a> \
3497 / # Match all URLs</pre>
3501 <p>The default behavior is now set.</p>
3504 <h3 class="SECT3"><a name="DEFAULT-ACTION" id="DEFAULT-ACTION">8.7.2. default.action</a></h3>
3505 <p>If you aren't a developer, there's no need for you to edit the <tt class="FILENAME">default.action</tt>
3506 file. It is maintained by the <span class="APPLICATION">Privoxy</span> developers and if you disagree with some
3507 of the sections, you should overrule them in your <tt class="FILENAME">user.action</tt>.</p>
3508 <p>Understanding the <tt class="FILENAME">default.action</tt> file can help you with your <tt class=
3509 "FILENAME">user.action</tt>, though.</p>
3510 <p>The first section in this file is a special section for internal use that prevents older <span class=
3511 "APPLICATION">Privoxy</span> versions from reading the file:</p>
3512 <table border="0" bgcolor="#E0E0E0" width="100%">
3515 <pre class="SCREEN"> ##########################################################################
3516 # Settings -- Don't change! For internal Privoxy use ONLY.
3517 ##########################################################################
3519 for-privoxy-version=3.0.11</pre>
3523 <p>After that comes the (optional) alias section. We'll use the example section from the above <a href=
3524 "actions-file.html#ALIASES">chapter on aliases</a>, that also explains why and how aliases are used:</p>
3525 <table border="0" bgcolor="#E0E0E0" width="100%">
3528 <pre class="SCREEN"> ##########################################################################
3530 ##########################################################################
3533 # These aliases just save typing later:
3534 # (Note that some already use other aliases!)
3536 +crunch-all-cookies = +<a href="actions-file.html#CRUNCH-INCOMING-COOKIES">crunch-incoming-cookies</a> +<a href=
3537 "actions-file.html#CRUNCH-OUTGOING-COOKIES">crunch-outgoing-cookies</a>
3538 -crunch-all-cookies = -<a href="actions-file.html#CRUNCH-INCOMING-COOKIES">crunch-incoming-cookies</a> -<a href=
3539 "actions-file.html#CRUNCH-OUTGOING-COOKIES">crunch-outgoing-cookies</a>
3540 +block-as-image = +block{Blocked image.} +handle-as-image
3541 mercy-for-cookies = -crunch-all-cookies -<a href=
3542 "actions-file.html#SESSION-COOKIES-ONLY">session-cookies-only</a> -<a href=
3543 "actions-file.html#FILTER-CONTENT-COOKIES">filter{content-cookies}</a>
3545 # These aliases define combinations of actions
3546 # that are useful for certain types of sites:
3548 fragile = -<a href="actions-file.html#BLOCK">block</a> -<a href=
3549 "actions-file.html#FILTER">filter</a> -crunch-all-cookies -<a href=
3550 "actions-file.html#FAST-REDIRECTS">fast-redirects</a> -<a href="actions-file.html#HIDE-REFERER">hide-referrer</a>
3551 shop = -crunch-all-cookies -<a href="actions-file.html#FILTER-ALL-POPUPS">filter{all-popups}</a></pre>
3555 <p>The first of our specialized sections is concerned with <span class="QUOTE">"fragile"</span> sites, i.e.
3556 sites that require minimum interference, because they are either very complex or very keen on tracking you (and
3557 have mechanisms in place that make them unusable for people who avoid being tracked). We will use our
3558 pre-defined <tt class="LITERAL">fragile</tt> alias instead of stating the list of actions explicitly:</p>
3559 <table border="0" bgcolor="#E0E0E0" width="100%">
3562 <pre class="SCREEN"> ##########################################################################
3563 # Exceptions for sites that'll break under the default action set:
3564 ##########################################################################
3566 # "Fragile" Use a minimum set of actions for these sites (see alias above):
3569 .office.microsoft.com # surprise, surprise!
3570 .windowsupdate.microsoft.com
3571 mail.google.com</pre>
3575 <p>Shopping sites are not as fragile, but they typically require cookies to log in, and pop-up windows for
3576 shopping carts or item details. Again, we'll use a pre-defined alias:</p>
3577 <table border="0" bgcolor="#E0E0E0" width="100%">
3580 <pre class="SCREEN"> # Shopping sites:
3584 .worldpay.com # for quietpc.com
3590 <p>The <tt class="LITERAL"><a href="actions-file.html#FAST-REDIRECTS">fast-redirects</a></tt> action, which may
3591 have been enabled in <tt class="FILENAME">match-all.action</tt>, breaks some sites. So disable it for popular
3592 sites where we know it misbehaves:</p>
3593 <table border="0" bgcolor="#E0E0E0" width="100%">
3596 <pre class="SCREEN"> { -<a href="actions-file.html#FAST-REDIRECTS">fast-redirects</a> }
3600 .altavista.com/.*(like|url|link):http
3601 .altavista.com/trans.*urltext=http
3606 <p>It is important that <span class="APPLICATION">Privoxy</span> knows which URLs belong to images, so that
3607 <span class="emphasis"><i class="EMPHASIS">if</i></span> they are to be blocked, a substitute image can be
3608 sent, rather than an HTML page. Contacting the remote site to find out is not an option, since it would destroy
3609 the loading time advantage of banner blocking, and it would feed the advertisers information about you. We can
3610 mark any URL as an image with the <tt class="LITERAL"><a href=
3611 "actions-file.html#HANDLE-AS-IMAGE">handle-as-image</a></tt> action, and marking all URLs that end in a known
3612 image file extension is a good start:</p>
3613 <table border="0" bgcolor="#E0E0E0" width="100%">
3616 <pre class="SCREEN"> ##########################################################################
3618 ##########################################################################
3620 # Define which file types will be treated as images, in case they get
3621 # blocked further down this file:
3623 { +<a href="actions-file.html#HANDLE-AS-IMAGE">handle-as-image</a> }
3624 /.*\.(gif|jpe?g|png|bmp|ico)$</pre>
3628 <p>And then there are known banner sources. They often use scripts to generate the banners, so it won't be
3629 visible from the URL that the request is for an image. Hence we block them <span class="emphasis"><i class=
3630 "EMPHASIS">and</i></span> mark them as images in one go, with the help of our <tt class=
3631 "LITERAL">+block-as-image</tt> alias defined above. (We could of course just as well use <tt class=
3632 "LITERAL">+<a href="actions-file.html#BLOCK">block</a> +<a href=
3633 "actions-file.html#HANDLE-AS-IMAGE">handle-as-image</a></tt> here.) Remember that the type of the replacement
3634 image is chosen by the <tt class="LITERAL"><a href=
3635 "actions-file.html#SET-IMAGE-BLOCKER">set-image-blocker</a></tt> action. Since all URLs have matched the
3636 default section with its <tt class="LITERAL">+<a href=
3637 "actions-file.html#SET-IMAGE-BLOCKER">set-image-blocker</a>{pattern}</tt> action before, it still applies and
3638 needn't be repeated:</p>
3639 <table border="0" bgcolor="#E0E0E0" width="100%">
3642 <pre class="SCREEN"> # Known ad generators:
3647 .ad.*.doubleclick.net
3648 .a.yimg.com/(?:(?!/i/).)*$
3649 .a[0-9].yimg.com/(?:(?!/i/).)*$
3655 <p>One of the most important jobs of <span class="APPLICATION">Privoxy</span> is to block banners. Many of
3656 these can be <span class="QUOTE">"blocked"</span> by the <tt class="LITERAL"><a href=
3657 "actions-file.html#FILTER">filter</a>{banners-by-size}</tt> action, which we enabled above, and which deletes
3658 the references to banner images from the pages while they are loaded, so the browser doesn't request them
3659 anymore, and hence they don't need to be blocked here. But this naturally doesn't catch all banners, and some
3660 people choose not to use filters, so we need a comprehensive list of patterns for banner URLs here, and apply
3661 the <tt class="LITERAL"><a href="actions-file.html#BLOCK">block</a></tt> action to them.</p>
3662 <p>First comes many generic patterns, which do most of the work, by matching typical domain and path name
3663 components of banners. Then comes a list of individual patterns for specific sites, which is omitted here to
3664 keep the example short:</p>
3665 <table border="0" bgcolor="#E0E0E0" width="100%">
3668 <pre class="SCREEN"> ##########################################################################
3669 # Block these fine banners:
3670 ##########################################################################
3671 { <a href="actions-file.html#BLOCK">+block{Banner ads.}</a> }
3679 /.*count(er)?\.(pl|cgi|exe|dll|asp|php[34]?)
3680 /(?:.*/)?(publicite|werbung|rekla(ma|me|am)|annonse|maino(kset|nta|s)?)/
3682 # Site-specific patterns (abbreviated):
3688 <p>It's quite remarkable how many advertisers actually call their banner servers ads.<tt class=
3689 "REPLACEABLE"><i>company</i></tt>.com, or call the directory in which the banners are stored literally
3690 <span class="QUOTE">"banners"</span>. So the above generic patterns are surprisingly effective.</p>
3691 <p>But being very generic, they necessarily also catch URLs that we don't want to block. The pattern <tt class=
3692 "LITERAL">.*ads.</tt> e.g. catches <span class="QUOTE">"nasty-<span class="emphasis"><i class=
3693 "EMPHASIS">ads</i></span>.nasty-corp.com"</span> as intended, but also <span class="QUOTE">"downlo<span class=
3694 "emphasis"><i class="EMPHASIS">ads</i></span>.sourcefroge.net"</span> or <span class="QUOTE">"<span class=
3695 "emphasis"><i class="EMPHASIS">ads</i></span>l.some-provider.net."</span> So here come some well-known
3696 exceptions to the <tt class="LITERAL">+<a href="actions-file.html#BLOCK">block</a></tt> section above.</p>
3697 <p>Note that these are exceptions to exceptions from the default! Consider the URL <span class=
3698 "QUOTE">"downloads.sourcefroge.net"</span>: Initially, all actions are deactivated, so it wouldn't get blocked.
3699 Then comes the defaults section, which matches the URL, but just deactivates the <tt class="LITERAL"><a href=
3700 "actions-file.html#BLOCK">block</a></tt> action once again. Then it matches <tt class="LITERAL">.*ads.</tt>, an
3701 exception to the general non-blocking policy, and suddenly <tt class="LITERAL"><a href=
3702 "actions-file.html#BLOCK">+block</a></tt> applies. And now, it'll match <tt class="LITERAL">.*loads.</tt>,
3703 where <tt class="LITERAL"><a href="actions-file.html#BLOCK">-block</a></tt> applies, so (unless it matches
3704 <span class="emphasis"><i class="EMPHASIS">again</i></span> further down) it ends up with no <tt class=
3705 "LITERAL"><a href="actions-file.html#BLOCK">block</a></tt> action applying.</p>
3706 <table border="0" bgcolor="#E0E0E0" width="100%">
3709 <pre class="SCREEN"> ##########################################################################
3710 # Save some innocent victims of the above generic block patterns:
3711 ##########################################################################
3715 { -<a href="actions-file.html#BLOCK">block</a> }
3716 adv[io]*. # (for advogato.org and advice.*)
3717 adsl. # (has nothing to do with ads)
3718 adobe. # (has nothing to do with ads either)
3719 ad[ud]*. # (adult.* and add.*)
3720 .edu # (universities don't host banners (yet!))
3721 .*loads. # (downloads, uploads etc)
3729 www.globalintersec.com/adv # (adv = advanced)
3730 www.ugu.com/sui/ugu/adv</pre>
3734 <p>Filtering source code can have nasty side effects, so make an exception for our friends at sourceforge.net,
3735 and all paths with <span class="QUOTE">"cvs"</span> in them. Note that <tt class="LITERAL">-<a href=
3736 "actions-file.html#FILTER">filter</a></tt> disables <span class="emphasis"><i class="EMPHASIS">all</i></span>
3737 filters in one fell swoop!</p>
3738 <table border="0" bgcolor="#E0E0E0" width="100%">
3741 <pre class="SCREEN"> # Don't filter code!
3743 { -<a href="actions-file.html#FILTER">filter</a> }
3748 .sourceforge.net</pre>
3752 <p>The actual <tt class="FILENAME">default.action</tt> is of course much more comprehensive, but we hope this
3753 example made clear how it works.</p>
3756 <h3 class="SECT3"><a name="USER-ACTION" id="USER-ACTION">8.7.3. user.action</a></h3>
3757 <p>So far we are painting with a broad brush by setting general policies, which would be a reasonable starting
3758 point for many people. Now, you might want to be more specific and have customized rules that are more suitable
3759 to your personal habits and preferences. These would be for narrowly defined situations like your ISP or your
3760 bank, and should be placed in <tt class="FILENAME">user.action</tt>, which is parsed after all other actions
3761 files and hence has the last word, over-riding any previously defined actions. <tt class=
3762 "FILENAME">user.action</tt> is also a <span class="emphasis"><i class="EMPHASIS">safe</i></span> place for your
3763 personal settings, since <tt class="FILENAME">default.action</tt> is actively maintained by the <span class=
3764 "APPLICATION">Privoxy</span> developers and you'll probably want to install updated versions from time to
3766 <p>So let's look at a few examples of things that one might typically do in <tt class=
3767 "FILENAME">user.action</tt>:</p>
3768 <table border="0" bgcolor="#E0E0E0" width="100%">
3771 <pre class="SCREEN"> # My user.action file. <fred@example.com></pre>
3775 <p>As <a href="actions-file.html#ALIASES">aliases</a> are local to the actions file that they are defined in,
3776 you can't use the ones from <tt class="FILENAME">default.action</tt>, unless you repeat them here:</p>
3777 <table border="0" bgcolor="#E0E0E0" width="100%">
3780 <pre class="SCREEN"> # Aliases are local to the file they are defined in.
3781 # (Re-)define aliases for this file:
3785 # These aliases just save typing later, and the alias names should
3786 # be self explanatory.
3788 +crunch-all-cookies = +crunch-incoming-cookies +crunch-outgoing-cookies
3789 -crunch-all-cookies = -crunch-incoming-cookies -crunch-outgoing-cookies
3790 allow-all-cookies = -crunch-all-cookies -session-cookies-only
3791 allow-popups = -filter{all-popups}
3792 +block-as-image = +block{Blocked as image.} +handle-as-image
3793 -block-as-image = -block
3795 # These aliases define combinations of actions that are useful for
3796 # certain types of sites:
3798 fragile = -block -crunch-all-cookies -filter -fast-redirects -hide-referrer
3799 shop = -crunch-all-cookies allow-popups
3801 # Allow ads for selected useful free sites:
3803 allow-ads = -block -filter{banners-by-size} -filter{banners-by-link}
3805 # Alias for specific file types that are text, but might have conflicting
3806 # MIME types. We want the browser to force these to be text documents.
3807 handle-as-text = -<a href="actions-file.html#FILTER">filter</a> +-<a href=
3808 "actions-file.html#CONTENT-TYPE-OVERWRITE">content-type-overwrite{text/plain}</a> +-<a href=
3809 "actions-file.html#FORCE-TEXT-MODE">force-text-mode</a> -<a href=
3810 "actions-file.html#HIDE-CONTENT-DISPOSITION">hide-content-disposition</a></pre>
3814 <p>Say you have accounts on some sites that you visit regularly, and you don't want to have to log in manually
3815 each time. So you'd like to allow persistent cookies for these sites. The <tt class=
3816 "LITERAL">allow-all-cookies</tt> alias defined above does exactly that, i.e. it disables crunching of cookies
3817 in any direction, and the processing of cookies to make them only temporary.</p>
3818 <table border="0" bgcolor="#E0E0E0" width="100%">
3821 <pre class="SCREEN"> { allow-all-cookies }
3829 <p>Your bank is allergic to some filter, but you don't know which, so you disable them all:</p>
3830 <table border="0" bgcolor="#E0E0E0" width="100%">
3833 <pre class="SCREEN"> { -<a href="actions-file.html#FILTER">filter</a> }
3834 .your-home-banking-site.com</pre>
3838 <p>Some file types you may not want to filter for various reasons:</p>
3839 <table border="0" bgcolor="#E0E0E0" width="100%">
3842 <pre class="SCREEN"> # Technical documentation is likely to contain strings that might
3843 # erroneously get altered by the JavaScript-oriented filters:
3848 # And this stupid host sends streaming video with a wrong MIME type,
3849 # so that Privoxy thinks it is getting HTML and starts filtering:
3851 stupid-server.example.com/</pre>
3855 <p>Example of a simple <a href="actions-file.html#BLOCK">block</a> action. Say you've seen an ad on your
3856 favourite page on example.com that you want to get rid of. You have right-clicked the image, selected
3857 <span class="QUOTE">"copy image location"</span> and pasted the URL below while removing the leading http://,
3858 into a <tt class="LITERAL">{ +block{} }</tt> section. Note that <tt class="LITERAL">{ +handle-as-image }</tt>
3859 need not be specified, since all URLs ending in <tt class="LITERAL">.gif</tt> will be tagged as images by the
3860 general rules as set in default.action anyway:</p>
3861 <table border="0" bgcolor="#E0E0E0" width="100%">
3864 <pre class="SCREEN"> { +<a href="actions-file.html#BLOCK">block</a>{Nasty ads.} }
3865 www.example.com/nasty-ads/sponsor\.gif
3866 another.example.net/more/junk/here/</pre>
3870 <p>The URLs of dynamically generated banners, especially from large banner farms, often don't use the
3871 well-known image file name extensions, which makes it impossible for <span class="APPLICATION">Privoxy</span>
3872 to guess the file type just by looking at the URL. You can use the <tt class="LITERAL">+block-as-image</tt>
3873 alias defined above for these cases. Note that objects which match this rule but then turn out NOT to be an
3874 image are typically rendered as a <span class="QUOTE">"broken image"</span> icon by the browser. Use
3876 <table border="0" bgcolor="#E0E0E0" width="100%">
3879 <pre class="SCREEN"> { +block-as-image }
3883 ar.atwola.com/</pre>
3887 <p>Now you noticed that the default configuration breaks Forbes Magazine, but you were too lazy to find out
3888 which action is the culprit, and you were again too lazy to give <a href="contact.html">feedback</a>, so you
3889 just used the <tt class="LITERAL">fragile</tt> alias on the site, and -- <span class="emphasis"><i class=
3890 "EMPHASIS">whoa!</i></span> -- it worked. The <tt class="LITERAL">fragile</tt> aliases disables those actions
3891 that are most likely to break a site. Also, good for testing purposes to see if it is <span class=
3892 "APPLICATION">Privoxy</span> that is causing the problem or not. We later find other regular sites that
3893 misbehave, and add those to our personalized list of troublemakers:</p>
3894 <table border="0" bgcolor="#E0E0E0" width="100%">
3897 <pre class="SCREEN"> { fragile }
3904 <p>You like the <span class="QUOTE">"fun"</span> text replacements in <tt class="FILENAME">default.filter</tt>,
3905 but it is disabled in the distributed actions file. So you'd like to turn it on in your private, update-safe
3906 config, once and for all:</p>
3907 <table border="0" bgcolor="#E0E0E0" width="100%">
3910 <pre class="SCREEN"> { +<a href="actions-file.html#FILTER-FUN">filter{fun}</a> }
3911 / # For ALL sites!</pre>
3915 <p>Note that the above is not really a good idea: There are exceptions to the filters in <tt class=
3916 "FILENAME">default.action</tt> for things that really shouldn't be filtered, like code on CVS->Web
3917 interfaces. Since <tt class="FILENAME">user.action</tt> has the last word, these exceptions won't be valid for
3918 the <span class="QUOTE">"fun"</span> filtering specified here.</p>
3919 <p>You might also worry about how your favourite free websites are funded, and find that they rely on
3920 displaying banner advertisements to survive. So you might want to specifically allow banners for those sites
3921 that you feel provide value to you:</p>
3922 <table border="0" bgcolor="#E0E0E0" width="100%">
3925 <pre class="SCREEN"> { allow-ads }
3932 <p>Note that <tt class="LITERAL">allow-ads</tt> has been aliased to <tt class="LITERAL">-<a href=
3933 "actions-file.html#BLOCK">block</a></tt>, <tt class="LITERAL">-<a href=
3934 "actions-file.html#FILTER-BANNERS-BY-SIZE">filter{banners-by-size}</a></tt>, and <tt class="LITERAL">-<a href=
3935 "actions-file.html#FILTER-BANNERS-BY-LINK">filter{banners-by-link}</a></tt> above.</p>
3936 <p>Invoke another alias here to force an over-ride of the MIME type <tt class="LITERAL">application/x-sh</tt>
3937 which typically would open a download type dialog. In my case, I want to look at the shell script, and then I
3938 can save it should I choose to.</p>
3939 <table border="0" bgcolor="#E0E0E0" width="100%">
3942 <pre class="SCREEN"> { handle-as-text }
3947 <p><tt class="FILENAME">user.action</tt> is generally the best place to define exceptions and additions to the
3948 default policies of <tt class="FILENAME">default.action</tt>. Some actions are safe to have their default
3949 policies set here though. So let's set a default policy to have a <span class="QUOTE">"blank"</span> image as
3950 opposed to the checkerboard pattern for <span class="emphasis"><i class="EMPHASIS">ALL</i></span> sites.
3951 <span class="QUOTE">"/"</span> of course matches all URL paths and patterns:</p>
3952 <table border="0" bgcolor="#E0E0E0" width="100%">
3955 <pre class="SCREEN"> { +<a href="actions-file.html#SET-IMAGE-BLOCKER">set-image-blocker{blank}</a> }
3963 <div class="NAVFOOTER">
3964 <hr align="left" width="100%">
3965 <table summary="Footer navigation table" width="100%" border="0" cellpadding="0" cellspacing="0">
3967 <td width="33%" align="left" valign="top"><a href="config.html" accesskey="P">Prev</a></td>
3968 <td width="34%" align="center" valign="top"><a href="index.html" accesskey="H">Home</a></td>
3969 <td width="33%" align="right" valign="top"><a href="filter-file.html" accesskey="N">Next</a></td>
3972 <td width="33%" align="left" valign="top">The Main Configuration File</td>
3973 <td width="34%" align="center" valign="top"> </td>
3974 <td width="33%" align="right" valign="top">Filter Files</td>