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35 <h1 class="SECT1"><a name="CONFIGURATION" id="CONFIGURATION">3.
36 Configuration</a></h1>
38 <h3 class="SECT2"><a name="ACTIONSFILE" id="ACTIONSFILE">3.1. What
39 exactly is an <span class="QUOTE">"actions"</span> file?</a></h3>
40 <p><span class="APPLICATION">Privoxy</span> utilizes the concept of
41 <span class="QUOTE">" <a href=
42 "../user-manual/actions-file.html#ACTIONS" target=
43 "_top">actions</a>"</span> that are used to manipulate and control web
44 page data. <a href="../user-manual/actions-file.html" target=
45 "_top">Actions files</a> are where these <a href=
46 "../user-manual/actions-file.html#ACTIONS" target="_top">actions</a>
47 that <span class="APPLICATION">Privoxy</span> could take while
48 processing a certain request, are configured. Typically, you would
49 define a set of default actions that apply globally to all URLs, then
50 add exceptions to these defaults where needed. There is a wide array of
51 actions available that give the user a high degree of control and
52 flexibility on how to process each and every web page.</p>
53 <p>Actions can be defined on a <a href=
54 "../user-manual/actions-file.html#AF-PATTERNS" target="_top">URL
55 pattern</a> basis, i.e. for single URLs, whole web sites, groups or
56 parts thereof etc. Actions can also be grouped together and then
57 applied to requests matching one or more patterns. There are many
58 possible actions that might apply to any given site. As an example, if
59 you are blocking <a href="http://en.wikipedia.org/wiki/Browser_cookie"
60 target="_top">cookies</a> as one of your default actions, but need to
61 accept cookies from a given site, you would need to define an exception
62 for this site in one of your actions files, preferably in <tt class=
63 "FILENAME">user.action</tt>.</p>
66 <h3 class="SECT2"><a name="ACTIONSS" id="ACTIONSS">3.2. The
67 <span class="QUOTE">"actions"</span> concept confuses me. Please list
68 some of these <span class="QUOTE">"actions"</span>.</a></h3>
69 <p>For a comprehensive discussion of the actions concept, please refer
70 to the <a href="../user-manual/actions-file.html" target="_top">actions
71 file chapter</a> in the <a href="../user-manual/index.html" target=
72 "_top">User Manual</a>. It includes a <a href=
73 "../user-manual/actions-file.html#ACTIONS" target="_top">list of all
74 actions</a> and an <a href=
75 "../user-manual/actions-file.html#ACT-EXAMPLES" target="_top">actions
76 file tutorial</a> to get you started.</p>
79 <h3 class="SECT2"><a name="ACTCONFIG" id="ACTCONFIG">3.3. How are
80 actions files configured? What is the easiest way to do this?</a></h3>
81 <p>Actions files are just text files in a special syntax and can be
82 edited with a text editor. But probably the easiest way is to access
83 <span class="APPLICATION">Privoxy</span>'s user interface with your web
84 browser at <a href="http://config.privoxy.org/" target=
85 "_top">http://config.privoxy.org/</a> (Shortcut: <a href="http://p.p/"
86 target="_top">http://p.p/</a>) and then select <span class=
87 "QUOTE">"<a href="http://config.privoxy.org/show-status" target=
88 "_top">View & change the current configuration</a>"</span> from the
89 menu. Note that this feature must be explicitly enabled in the main
90 config file (see <a href=
91 "../user-manual/config.html#ENABLE-EDIT-ACTIONS" target=
92 "_top">enable-edit-actions</a>).</p>
95 <h3 class="SECT2"><a name="AEN420" id="AEN420">3.4. There are several
96 different <span class="QUOTE">"actions"</span> files. What are the
98 <p>Please have a look at the <a href="../user-manual/actions-file.html"
99 target="_top">the actions chapter</a> in the <a href=
100 "../user-manual/index.html" target="_top">User Manual</a> for a
101 detailed explanation.</p>
104 <h3 class="SECT2"><a name="GETUPDATES" id="GETUPDATES">3.5. Where can I
105 get updated Actions Files?</a></h3>
106 <p>Based on your feedback and the continuing development, updates of
107 <tt class="FILENAME">default.action</tt> will be made available from
108 time to time on the <a href=
109 "https://sourceforge.net/project/showfiles.php?group_id=11118" target=
110 "_top">files section</a> of our <a href=
111 "https://sourceforge.net/projects/ijbswa/" target="_top">project
113 <p>If you wish to receive an email notification whenever we release
114 updates of <span class="APPLICATION">Privoxy</span> or the actions
116 "https://lists.privoxy.org/mailman/listinfo/privoxy-announce" target=
117 "_top">subscribe to our announce mailing list</a>,
118 privoxy-announce@lists.privoxy.org.</p>
121 <h3 class="SECT2"><a name="NEWCONFIG" id="NEWCONFIG">3.6. Can I use my
122 old config files?</a></h3>
123 <p>The syntax and purpose of configuration files has remained roughly
124 the same throughout the 3.x series, but backwards compatibility is not
125 guaranteed. Also each release contains updated, <span class=
126 "QUOTE">"improved"</span> versions and it is therefore strongly
127 recommended to install the newer configuration files and merge back
128 your modifications.</p>
131 <h3 class="SECT2"><a name="DIFFICULT" id="DIFFICULT">3.7. Why is the
132 configuration so complicated?</a></h3>
133 <p><span class="QUOTE">"Complicated"</span> is in the eye of the
135 <p>Privoxy is currently mainly written by and for people who are
136 already familiar with the underlying concepts like regular expressions,
137 HTTP and HTML, or are willing to become familiar with them to be able
138 to get the most out of a powerful and flexible tool such as
140 <p>While everybody is expected to be able to get a Privoxy default
141 installation up and running, fine-tuning requires a certain amount of
142 background information and Privoxy's documentation mainly concentrates
143 on the Privoxy-specific parts while only providing references to the
145 <p>If you or anyone you know has the skills, time and energy to reduce
146 the barrier of entry, please <a href="general.html#PARTICIPATE">get
150 <h3 class="SECT2"><a name="YAHOO" id="YAHOO">3.8. How can I make my
151 Yahoo/Hotmail/Gmail account work?</a></h3>
152 <p>The default configuration shouldn't impact the usability of any of
153 these services. It may, however, make all <a href=
154 "http://en.wikipedia.org/wiki/Browser_cookie" target="_top">cookies</a>
155 temporary, so that your browser will forget your login credentials in
156 between browser sessions. If you would like not to have to log in
157 manually each time you access those websites, simply turn off all
158 cookie handling for them in the <tt class="FILENAME">user.action</tt>
159 file. An example for yahoo might look like:</p>
160 <table border="0" bgcolor="#E0E0E0" width="100%">
163 <pre class="SCREEN"># Allow all cookies for Yahoo login:
165 { -<a href="../user-manual/actions-file.html#CRUNCH-INCOMING-COOKIES" target=
166 "_top">crunch-incoming-cookies</a> -<a href=
167 "../user-manual/actions-file.html#CRUNCH-OUTGOING-COOKIES" target=
168 "_top">crunch-outgoing-cookies</a> -<a href=
169 "../user-manual/actions-file.html#SESSION-COOKIES-ONLY" target=
170 "_top">session-cookies-only</a> }
171 .login.yahoo.com</pre>
175 <p>These kinds of sites are often quite complex and heavy with <a href=
176 "http://en.wikipedia.org/wiki/Javascript" target="_top">Javascript</a>
177 and thus <span class="QUOTE">"fragile"</span>. So if <span class=
178 "emphasis"><i class="EMPHASIS">still</i></span> a problem, we have an
179 <a href="../user-manual/actions-file.html#ALIASES" target=
180 "_top">alias</a> just for such sticky situations:</p>
181 <table border="0" bgcolor="#E0E0E0" width="100%">
184 <pre class="SCREEN"># Gmail is a _fragile_ site:
186 { <tt class="LITERAL">fragile</tt> }
188 mail.google.com</pre>
192 <p>Be sure to flush your browser's caches whenever making these kinds
193 of changes, just to make sure the changes <span class=
194 "QUOTE">"take"</span>.</p>
195 <p>Make sure the domain, host and path are appropriate as well. Your
196 browser can tell you where you are specifically and you should use that
197 information for your configuration settings. Note that above it is not
198 referenced as <tt class="LITERAL">gmail.com</tt>, which is a valid
202 <h3 class="SECT2"><a name="CONFIGFILES" id="CONFIGFILES">3.9. What's
203 the difference between the <span class="QUOTE">"Cautious"</span>,
204 <span class="QUOTE">"Medium"</span> and <span class=
205 "QUOTE">"Advanced"</span> defaults?</a></h3>
206 <p>Configuring <span class="APPLICATION">Privoxy</span> is not entirely
207 trivial. To help you get started, we provide you with three different
208 default action <span class="QUOTE">"profiles"</span> in the web based
209 actions file editor at <a href="http://config.privoxy.org/show-status"
210 target="_top">http://config.privoxy.org/show-status</a>. See the
211 <a href="../user-manual/actions-file.html" target="_top"><i class=
212 "CITETITLE">User Manual</i></a> for a list of actions, and how the
213 default profiles are set.</p>
214 <p>Where the defaults are likely to break some sites, exceptions for
215 known popular <span class="QUOTE">"problem"</span> sites are included,
216 but in general, the more aggressive your default settings are, the more
217 exceptions you will have to make later. New users are best to start off
218 in <span class="QUOTE">"Cautious"</span> setting. This is safest and
219 will have the fewest problems. See the <a href=
220 "../user-manual/index.html" target="_top"><i class="CITETITLE">User
221 Manual</i></a> for a more detailed discussion.</p>
222 <p>It should be noted that the <span class="QUOTE">"Advanced"</span>
223 profile (formerly known as the <span class=
224 "QUOTE">"Adventuresome"</span> profile) is more aggressive, and will
225 make use of some of <span class="APPLICATION">Privoxy's</span> advanced
226 features. Use at your own risk!</p>
229 <h3 class="SECT2"><a name="BROWSECONFIG" id="BROWSECONFIG">3.10. Why
230 can I change the configuration with a browser? Does that not raise
231 security issues?</a></h3>
232 <p>It may seem strange that regular users can edit the config files
233 with their browsers, although the whole <tt class=
234 "FILENAME">/etc/privoxy</tt> hierarchy belongs to the user <span class=
235 "QUOTE">"privoxy"</span>, with only 644 permissions.</p>
236 <p>When you use the browser-based editor, <span class=
237 "APPLICATION">Privoxy</span> itself is writing to the config files.
238 Because <span class="APPLICATION">Privoxy</span> is running as the user
239 <span class="QUOTE">"privoxy"</span>, it can update its own config
241 <p>If you run <span class="APPLICATION">Privoxy</span> for multiple
242 untrusted users (e.g. in a LAN) or aren't entirely in control of your
243 own browser, you will probably want to make sure that the web-based
244 editor and remote toggle features are <span class="QUOTE">"off"</span>
245 by setting <span class="QUOTE">"<tt class="LITERAL"><a href=
246 "../user-manual/config.html#ENABLE-EDIT-ACTIONS" target=
247 "_top">enable-edit-actions</a> 0</tt>"</span> and <span class=
248 "QUOTE">"<tt class="LITERAL"><a href=
249 "../user-manual/config.html#ENABLE-REMOTE-TOGGLE" target=
250 "_top">enable-remote-toggle</a> 0</tt>"</span> in the <a href=
251 "../user-manual/config.html" target="_top">main configuration
253 <p>As of <span class="APPLICATION">Privoxy</span> 3.0.7 these options
254 are disabled by default.</p>
257 <h3 class="SECT2"><a name="FILTERFILE" id="FILTERFILE">3.11. What is
258 the <tt class="FILENAME">default.filter</tt> file? What is a
259 <span class="QUOTE">"filter"</span>?</a></h3>
260 <p>The <a href="../user-manual/filter-file.html" target=
261 "_top"><tt class="FILENAME">default.filter</tt></a> file is where
262 <span class="emphasis"><i class="EMPHASIS">filters</i></span> as
263 supplied by the developers are defined. Filters are a special subset of
264 actions that can be used to modify or remove web page content or
265 headers on the fly. Content filters can be applied to <span class=
266 "emphasis"><i class="EMPHASIS">anything</i></span> in the page source,
267 header filters can be applied to either server or client headers.
268 Regular expressions are used to accomplish this.</p>
269 <p>There are a number of pre-defined filters to deal with common
270 annoyances. The filters are only defined here, to invoke them, you need
271 to use the <a href="../user-manual/actions-file.html#FILTER" target=
272 "_top"><tt class="LITERAL">filter</tt> action</a> in one of the actions
273 files. Content filtering is automatically disabled for inappropriate
274 MIME types, but if you know better than Privoxy what should or should
275 not be filtered you can filter any content you like.</p>
276 <p>Filters should <span class="emphasis"><i class=
277 "EMPHASIS">not</i></span> be confused with <a href=
278 "../user-manual/actions-file.html#BLOCK" target="_top"><tt class=
279 "LITERAL">blocks</tt></a>, which is a completely different action, and
280 is more typically used to block ads and unwanted sites.</p>
281 <p>If you are familiar with regular expressions, and HTML, you can look
282 at the provided <tt class="FILENAME">default.filter</tt> with a text
283 editor and define your own filters. This is potentially a very powerful
284 feature, but requires some expertise in both regular expressions and
285 HTML/HTTP. You should place any modifications to the default filters,
286 or any new ones you create in a separate file, such as <tt class=
287 "FILENAME">user.filter</tt>, so they won't be overwritten during
288 upgrades. The ability to define multiple filter files in <tt class=
289 "FILENAME">config</tt> is a new feature as of v. 3.0.5.</p>
290 <p>There is no GUI editor option for this part of the configuration,
291 but you can disable/enable the various pre-defined filters of the
292 included <tt class="FILENAME">default.filter</tt> file with the
293 <a href="http://config.privoxy.org/show-status" target="_top">web-based
294 actions file editor</a>. Note that the custom actions editor must be
295 explicitly enabled in the main config file (see <a href=
296 "../user-manual/config.html#ENABLE-EDIT-ACTIONS" target=
297 "_top">enable-edit-actions</a>).</p>
298 <p>If you intend to develop your own filters, you might want to have a
299 look at <a href="https://www.fabiankeil.de/sourcecode/pft/" target=
300 "_top">Privoxy-Filter-Test</a>.</p>
303 <h3 class="SECT2"><a name="LANCONFIG" id="LANCONFIG">3.12. How can I
304 set up Privoxy to act as a proxy for my LAN?</a></h3>
305 <p>By default, <span class="APPLICATION">Privoxy</span> only responds
306 to requests from <tt class="LITERAL">127.0.0.1</tt> (localhost). To
307 have it act as a server for a network, this needs to be changed in the
308 <a href="../user-manual/config.html" target="_top">main configuration
309 file</a>. Look for the <tt class="LITERAL"><a href=
310 "../user-manual/config.html#LISTEN-ADDRESS" target=
311 "_top">listen-address</a></tt> option, which may be commented out with
312 a <span class="QUOTE">"#"</span> symbol. Make sure it is uncommented,
313 and assign it the address of the LAN gateway interface, and port number
314 to use. Assuming your LAN address is 192.168.1.1 and you wish to run
315 <span class="APPLICATION">Privoxy</span> on port 8118, this line should
317 <table border="0" bgcolor="#E0E0E0" width="100%">
320 <pre class="SCREEN"> listen-address 192.168.1.1:8118</pre>
324 <p>Save the file, and restart <span class="APPLICATION">Privoxy</span>.
325 Configure all browsers on the network then to use this address and port
327 <p>Alternately, you can have <span class="APPLICATION">Privoxy</span>
328 listen on all available interfaces:</p>
329 <table border="0" bgcolor="#E0E0E0" width="100%">
332 <pre class="SCREEN"> listen-address :8118</pre>
336 <p>And then use <span class="APPLICATION">Privoxy's</span> <a href=
337 "../user-manual/config.html#PERMIT-ACCESS" target=
338 "_top">permit-access</a> feature to limit connections. A firewall in
339 this situation is recommended as well.</p>
340 <p>The above steps should be the same for any TCP network, regardless
341 of operating system.</p>
342 <p>If you run <span class="APPLICATION">Privoxy</span> on a LAN with
343 untrusted users, we recommend that you double-check the <a href=
344 "../user-manual/config.html#ACCESS-CONTROL" target="_top">access
345 control and security</a> options!</p>
348 <h3 class="SECT2"><a name="NOSEEUM" id="NOSEEUM">3.13. Instead of ads,
349 now I get a checkerboard pattern. I don't want to see
351 <p>The replacement for blocked images can be controlled with the
352 <a href="../user-manual/actions-file.html#SET-IMAGE-BLOCKER" target=
353 "_top"><tt class="LITERAL">set-image-blocker</tt> action</a>. You have
354 the choice of a checkerboard pattern, a transparent 1x1 GIF image (aka
355 <span class="QUOTE">"blank"</span>), or a redirect to a custom image of
356 your choice. Note that this choice only has effect for images which are
357 blocked as images, i.e. whose URLs match both a <tt class=
358 "LITERAL"><a href="../user-manual/actions-file.html#HANDLE-AS-IMAGE"
359 target="_top">handle-as-image</a></tt> <span class="emphasis"><i class=
360 "EMPHASIS">and</i></span> <tt class="LITERAL"><a href=
361 "../user-manual/actions-file.html#BLOCK" target="_top">block</a></tt>
363 <p>If you want to see nothing, then change the <a href=
364 "../user-manual/actions-file.html#SET-IMAGE-BLOCKER" target=
365 "_top"><tt class="LITERAL">set-image-blocker</tt> action</a> to
366 <span class="QUOTE">"blank"</span>. This can be done by editing the
367 <tt class="FILENAME">user.action</tt> file, or through the <a href=
368 "http://config.privoxy.org/show-status" target="_top">web-based actions
372 <h3 class="SECT2"><a name="WHYSEEUM" id="WHYSEEUM">3.14. Why would
373 anybody want to see a checkerboard pattern?</a></h3>
374 <p>Remember that <a href="general.html#WHATSANAD">telling which image
375 is an ad and which isn't</a>, is an educated guess. While we hope that
376 the standard configuration is rather smart, it will make occasional
377 mistakes. The checkerboard image is visually decent, and it shows you
378 where images have been blocked, which can be very helpful in case some
379 navigation aid or otherwise innocent image was erroneously blocked. It
380 is recommended for new users so they can <span class=
381 "QUOTE">"see"</span> what is happening. Some people might also enjoy
382 seeing how many banners they <span class="emphasis"><i class=
383 "EMPHASIS">don't</i></span> have to see.</p>
386 <h3 class="SECT2"><a name="BLOCKEDBYTEXT" id="BLOCKEDBYTEXT">3.15. I
387 see some images being replaced with text instead of the checkerboard
388 image. Why and how do I get rid of this?</a></h3>
389 <p>This happens when the banners are not embedded in the HTML code of
390 the page itself, but in separate HTML (sub)documents that are loaded
391 into (i)frames or (i)layers, and these external HTML documents are
392 blocked. Being non-images they get replaced by a substitute HTML page
393 rather than a substitute image, which wouldn't work out technically,
394 since the browser expects and accepts only HTML when it has requested
395 an HTML document.</p>
396 <p>The substitute page adapts to the available space and shows itself
397 as a miniature two-liner if loaded into small frames, or full-blown
398 with a large red "BLOCKED" banner if space allows.</p>
399 <p>If you prefer the banners to be blocked by images, you must see to
400 it that the HTML documents in which they are embedded are not blocked.
401 Clicking the <span class="QUOTE">"See why"</span> link offered in the
402 substitute page will show you which rule blocked the page. After
403 changing the rule and un-blocking the HTML documents, the browser will
404 try to load the actual banner images and the usual image blocking will
405 (hopefully!) kick in.</p>
408 <h3 class="SECT2"><a name="SRVANY" id="SRVANY">3.16. Can Privoxy run as
409 a service on Win2K/NT/XP?</a></h3>
410 <p>Yes. Version 3.0.5 introduces full <span class=
411 "APPLICATION">Windows</span> service functionality. See <a href=
412 "../user-manual/installation.html#installation-pack-win" target=
413 "_top">the <i class="CITETITLE">User Manual</i></a> for details on how
414 to install and configure <span class="APPLICATION">Privoxy</span> as a
416 <p>Earlier 3.x versions could run as a system service using <b class=
417 "COMMAND">srvany.exe</b>. See the discussion at <a href=
418 "https://sourceforge.net/tracker/?func=detail&atid=361118&aid=485617&group_id=11118"
420 "_top">https://sourceforge.net/tracker/?func=detail&atid=361118&aid=485617&group_id=11118</a>,
421 for details, and a sample configuration.</p>
424 <h3 class="SECT2"><a name="OTHERPROXY" id="OTHERPROXY">3.17. How can I
425 make Privoxy work with other proxies?</a></h3>
426 <p>This can be done and is often useful to combine the benefits of
427 <span class="APPLICATION">Privoxy</span> with those of a another proxy,
428 for example to cache content. See the <a href=
429 "../user-manual/config.html#FORWARDING" target="_top">forwarding
430 chapter</a> in the <a href="../user-manual/index.html" target=
431 "_top">User Manual</a> which describes how to do this. If you intend to
432 use Privoxy with Tor, please also have a look at <a href=
433 "misc.html#TOR">How do I use Privoxy together with Tor</a>.</p>
436 <h3 class="SECT2"><a name="PORT-80" id="PORT-80">3.18. Can I just set
437 Privoxy to use port 80 and thus avoid individual browser
438 configuration?</a></h3>
439 <p>No, its more complicated than that. This only works with special
440 kinds of proxies known as <span class="QUOTE">"intercepting"</span>
441 proxies (<a href="configuration.html#INTERCEPTING">see below</a>).</p>
444 <h3 class="SECT2"><a name="TRANSPARENT" id="TRANSPARENT">3.19. Can
445 Privoxy run as a <span class="QUOTE">"transparent"</span>
447 <p>The whole idea of Privoxy is to modify client requests and server
448 responses in all sorts of ways and therefore it's not a transparent
449 proxy as described in <a href="http://tools.ietf.org/html/rfc2616"
450 target="_top">RFC 2616</a>.</p>
451 <p>However, some people say <span class="QUOTE">"transparent
452 proxy"</span> when they mean <span class="QUOTE">"intercepting
453 proxy"</span>. If you are one of them, please read the <a href=
454 "configuration.html#INTERCEPTING">next entry</a>.</p>
457 <h3 class="SECT2"><a name="INTERCEPTING" id="INTERCEPTING">3.20. Can
458 Privoxy run as a <span class="QUOTE">"intercepting"</span>
460 <p><span class="APPLICATION">Privoxy</span> can't intercept traffic
461 itself, but it can handle requests that where intercepted and
462 redirected with a packet filter (like <span class=
463 "APPLICATION">PF</span> or <span class="APPLICATION">iptables</span>),
464 as long as the <tt class="LITERAL">Host</tt> header is present.</p>
465 <p>As the <tt class="LITERAL">Host</tt> header is required by HTTP/1.1
466 and as most web sites rely on it anyway, this limitation shouldn't be a
468 <p>Please refer to your packet filter's documentation to learn how to
469 intercept and redirect traffic into <span class=
470 "APPLICATION">Privoxy</span>. Afterward you just have to configure
471 <span class="APPLICATION">Privoxy</span> to <a href=
472 "../user-manual/config.html#ACCEPT-INTERCEPTED-REQUESTS" target=
473 "_top">accept intercepted requests</a>.</p>
476 <h3 class="SECT2"><a name="OUTLOOK" id="OUTLOOK">3.21. How can I
477 configure Privoxy for use with Outlook?</a></h3>
478 <p>Versions of <span class="APPLICATION">Outlook</span> prior to Office
479 2007, use <span class="APPLICATION">Internet Explorer</span> components
480 to both render HTML, and fetch any HTTP requests that may be embedded
481 in an HTML email. So however you have <span class=
482 "APPLICATION">Privoxy</span> configured to work with IE, this
483 configuration should automatically be shared, at least with older
484 version of Internet Explorer.</p>
485 <p>Starting with Office 2007, Microsoft is instead using the MS-Word
486 rendering engine with Outlook. It is unknown whether this can be
487 configured to use a proxy.</p>
490 <h3 class="SECT2"><a name="OUTLOOK-MORE" id="OUTLOOK-MORE">3.22. How
491 can I have separate rules just for HTML mail?</a></h3>
492 <p>The short answer is, you can't. <span class=
493 "APPLICATION">Privoxy</span> has no way of knowing which particular
494 application makes a request, so there is no way to distinguish between
495 web pages and HTML mail. <span class="APPLICATION">Privoxy</span> just
496 blindly proxies all requests. In the case of <span class=
497 "APPLICATION">Outlook Express</span> (see above), OE uses IE anyway,
498 and there is no way for <span class="APPLICATION">Privoxy</span> to
499 ever be able to distinguish between them (nor could any other proxy
500 type application for that matter).</p>
501 <p>For a good discussion of some of the issues involved (including
502 privacy and security issues), see <a href=
503 "https://sourceforge.net/tracker/?func=detail&atid=211118&aid=629518&group_id=11118"
505 "_top">https://sourceforge.net/tracker/?func=detail&atid=211118&aid=629518&group_id=11118</a>.</p>
508 <h3 class="SECT2"><a name="SNEAKY-COOKIES" id="SNEAKY-COOKIES">3.23. I
509 sometimes notice cookies sneaking through. How?</a></h3>
510 <p><a href="http://en.wikipedia.org/wiki/Browser_cookie" target=
511 "_top">Cookies</a> can be set in several ways. The classic method is
512 via the <tt class="LITERAL">Set-Cookie</tt> HTTP header. This is
513 straightforward, and an easy one to manipulate, such as the
514 <span class="APPLICATION">Privoxy</span> concept of <a href=
515 "../user-manual/actions-file.html#SESSION-COOKIES-ONLY" target=
516 "_top">session-cookies-only</a>. There is also the possibility of using
517 <a href="http://en.wikipedia.org/wiki/Javascript" target=
518 "_top">Javascript</a> to set cookies (<span class=
519 "APPLICATION">Privoxy</span> calls these <tt class=
520 "LITERAL">content-cookies</tt>). This is trickier because the syntax
521 can vary widely, and thus requires a certain amount of guesswork. It is
522 not realistic to catch all of these short of disabling Javascript,
523 which would break many sites. And lastly, if the cookies are embedded
524 in a HTTPS/SSL secure session via Javascript, they are beyond
525 <span class="APPLICATION">Privoxy's</span> reach.</p>
526 <p>All in all, <span class="APPLICATION">Privoxy</span> can help manage
527 cookies in general, can help minimize the loss of privacy posed by
528 cookies, but can't realistically stop all cookies.</p>
531 <h3 class="SECT2"><a name="EVIL-COOKIES" id="EVIL-COOKIES">3.24. Are
532 all cookies bad? Why?</a></h3>
533 <p>No, in fact there are many beneficial uses of <a href=
534 "http://en.wikipedia.org/wiki/Browser_cookie" target=
535 "_top">cookies</a>. Cookies are just a method that browsers can use to
536 store data between pages, or between browser sessions. Sometimes there
537 is a good reason for this, and the user's life is a bit easier as a
538 result. But there is a long history of some websites taking advantage
539 of this layer of trust, and using the data they glean from you and your
540 browsing habits for their own purposes, and maybe to your potential
541 detriment. Such sites are using you and storing their data on your
542 system. That is why the privacy conscious watch from whom those cookies
543 come, and why they really <span class="emphasis"><i class=
544 "EMPHASIS">need</i></span> to be there.</p>
545 <p>See the <a href="http://en.wikipedia.org/wiki/Browser_cookie"
546 target="_top">Wikipedia cookie definition</a> for more.</p>
549 <h3 class="SECT2"><a name="ALLOW-COOKIES" id="ALLOW-COOKIES">3.25. How
550 can I allow permanent cookies for my trusted sites?</a></h3>
551 <p>There are several actions that relate to cookies. The default
552 behavior is to allow only <span class="QUOTE">"session cookies"</span>,
553 which means the cookies only last for the current browser session. This
554 eliminates most kinds of abuse related to cookies. But there may be
555 cases where you want cookies to last.</p>
556 <p>To disable all cookie actions, so that cookies are allowed
557 unrestricted, both in and out, for <tt class=
558 "LITERAL">example.com</tt>:</p>
559 <table border="0" bgcolor="#E0E0E0" width="100%">
563 { -crunch-incoming-cookies -crunch-outgoing-cookies -session-cookies-only -filter{content-cookies} }
568 <p>Place the above in <tt class="FILENAME">user.action</tt>. Note that
569 some of these may be off by default anyway, so this might be redundant,
570 but there is no harm being explicit in what you want to happen.
571 <tt class="FILENAME">user.action</tt> includes an alias for this
572 situation, called <tt class="LITERAL">allow-all-cookies</tt>.</p>
575 <h3 class="SECT2"><a name="MULTIPLES" id="MULTIPLES">3.26. Can I have
576 separate configurations for different users?</a></h3>
577 <p>Each instance of <span class="APPLICATION">Privoxy</span> has its
578 own configuration, including such attributes as the TCP port that it
579 listens on. What you can do is run multiple instances of <span class=
580 "APPLICATION">Privoxy</span>, each with a unique <a href=
581 "../user-manual/config.html#LISTEN-ADDRESS" target=
582 "_top">listen-address</a> configuration setting, and configuration
583 path, and then each of these can have their own configurations. Think
584 of it as per-port configuration.</p>
585 <p>Simple enough for a few users, but for large installations, consider
586 having groups of users that might share like configurations.</p>
589 <h3 class="SECT2"><a name="WHITELISTS" id="WHITELISTS">3.27. Can I
590 set-up Privoxy as a whitelist of <span class="QUOTE">"good"</span>
592 <p>Sure. There are a couple of things you can do for simple
593 white-listing. Here's one real easy one:</p>
594 <table border="0" bgcolor="#E0E0E0" width="100%">
598 ############################################################
600 ############################################################
601 { <a href="../user-manual/actions-file.html#BLOCK" target=
605 ############################################################
607 ############################################################
608 { <a href="../user-manual/actions-file.html#BLOCK" target=
612 games.example.com</pre>
616 <p>This allows access to only those three sites by first blocking all
617 URLs, and then subsequently allowing three specific exceptions.</p>
618 <p>Another approach is <span class="APPLICATION">Privoxy's</span>
619 <tt class="LITERAL">trustfile</tt> concept, which incorporates the
620 notion of <span class="QUOTE">"trusted referrers"</span>. See the
621 <a href="../user-manual/config.html#TRUSTFILE" target="_top">Trust
622 documentation</a> for details.</p>
623 <p>These are fairly simple approaches and are not completely foolproof.
624 There are various other configuration options that should be disabled
625 (described elsewhere here and in <a href="../user-manual/" target=
626 "_top">the User Manual</a>) so that users can't modify their own
627 configuration and easily circumvent the whitelist.</p>
630 <h3 class="SECT2"><a name="NO-ADBLOCK" id="NO-ADBLOCK">3.28. How can I
631 turn off ad-blocking?</a></h3>
632 <p>Ad blocking is achieved through a complex application of various
633 <span class="APPLICATION">Privoxy</span> <a href=
634 "../user-manual/actions-file.html" target="_top">actions</a>. These
635 actions are deployed against simple images, banners, flash animations,
636 text pages, JavaScript, pop-ups and pop-unders, etc., so its not as
637 simple as just turning one or two actions off. The various actions that
638 make up <span class="APPLICATION">Privoxy</span> ad blocking are
639 hard-coded into the default configuration files. It has been assumed
640 that everyone using <span class="APPLICATION">Privoxy</span> is
641 interested in this particular feature.</p>
642 <p>If you want to do without this, there are several approaches you can
643 take: You can manually undo the many block rules in <tt class=
644 "FILENAME">default.action</tt>. Or even easier, just create your own
645 <tt class="FILENAME">default.action</tt> file from scratch without the
646 many ad blocking rules, and corresponding exceptions. Or lastly, if you
647 are not concerned about the additional blocks that are done for privacy
648 reasons, you can very easily over-ride <span class="emphasis"><i class=
649 "EMPHASIS">all</i></span> blocking with the following very simple rule
650 in your <tt class="FILENAME">user.action</tt>:</p>
651 <table border="0" bgcolor="#E0E0E0" width="100%">
654 <pre class="SCREEN"> # Unblock everybody, everywhere
655 { <a href="../user-manual/actions-file.html#BLOCK" target=
657 / # UN-Block *all* URLs</pre>
661 <p>Or even a more comprehensive reversing of various ad related
663 <table border="0" bgcolor="#E0E0E0" width="100%">
667 # Unblock everybody, everywhere, and turn off appropriate filtering, etc
668 { <a href="../user-manual/actions-file.html#BLOCK" target=
670 <a href="../user-manual/actions-file.html#FILTER-BANNERS-BY-SIZE" target=
671 "_top">-filter{banners-by-size}</a> \
672 <a href="../user-manual/actions-file.html#FILTER-BANNERS-BY-LINK" target=
673 "_top">-filter{banners-by-link}</a> \
674 <tt class="LITERAL">allow-popups</tt> \
676 / # UN-Block *all* URLs and allow ads</pre>
680 <p>This last <span class="QUOTE">"action"</span> in this compound
681 statement, <tt class="LITERAL">allow-popups</tt>, is an <a href=
682 "../user-manual/actions-file.html#ALIASES" target="_top">alias</a> that
683 disables various pop-up blocking features.</p>
686 <h3 class="SECT2"><a name="TEMPLATES" id="TEMPLATES">3.29. How can I
687 have custom template pages, like the <span class="emphasis"><i class=
688 "EMPHASIS">BLOCKED</i></span> page?</a></h3>
689 <p><span class="APPLICATION">Privoxy</span> <span class=
690 "QUOTE">"templates"</span> are specialized text files utilized by
691 <span class="APPLICATION">Privoxy</span> for various purposes and can
692 easily be modified using any text editor. All the template pages are
693 installed in a sub-directory appropriately named: <tt class=
694 "FILENAME">templates</tt>. Knowing something about HTML syntax will of
695 course be helpful.</p>
696 <p>Be forewarned that the default templates are subject to being
697 overwritten during upgrades. You can, however, create completely new
698 templates, place them in another directory and specify the alternate
699 path in the main <tt class="FILENAME">config</tt>. For details, have a
700 look at the <a href="../user-manual/config.html#templdir" target=
701 "_top">templdir</a> option.</p>
704 <h3 class="SECT2"><a name="BLOCKALL" id="BLOCKALL">3.30. How can I
705 remove the <span class="QUOTE">"Go There Anyway"</span> link from the
706 <span class="emphasis"><i class="EMPHASIS">BLOCKED</i></span>
708 <p>There is more than one way to do it (although Perl is not
710 <p>Editing the BLOCKED template page (see above) may dissuade some
711 users, but this method is easily circumvented. Where you need this
712 level of control, you might want to build <span class=
713 "APPLICATION">Privoxy</span> from source, and disable various features
714 that are available as compile-time options. You should <b class=
715 "COMMAND">configure</b> the sources as follows:</p>
716 <table border="0" bgcolor="#E0E0E0" width="100%">
720 ./configure --disable-toggle --disable-editor --disable-force</pre>
724 <p>This will create an executable with hard-coded security features so
725 that <span class="APPLICATION">Privoxy</span> does not allow easy
726 bypassing of blocked sites, or changing the current configuration via
727 any connected user's web browser.</p>
728 <p>Finally, all of these features can also be toggled on/off via
729 options in <span class="APPLICATION">Privoxy's</span> main <a href=
730 "../user-manual/config.html#ACCESS-CONTROL" target="_top">config</a>
731 file which means you don't have to recompile anything.</p>
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