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42 <a name="MISC">4. Miscellaneous</a>
46 <a name="SLOWSME">4.1. How much does Privoxy slow my browsing down?
47 This has to add extra time to browsing.</a>
50 How much of an impact depends on many things, including the CPU of
51 the host system, how aggressive the configuration is, which
52 specific actions are being triggered, the size of the page, the
53 bandwidth of the connection, etc.
56 Overall, it should not slow you down any in real terms, and may
57 actually help speed things up since ads, banners and other junk are
58 not typically being retrieved and displayed. The actual processing
59 time required by <span class="APPLICATION">Privoxy</span> itself
60 for each page, is relatively small in the overall scheme of things,
61 and happens very quickly. This is typically more than offset by
62 time saved not downloading and rendering ad images and other junk
63 content (if ad blocking is being used).
66 <span class="QUOTE">"Filtering"</span> content via the <tt class=
67 "LITERAL"><a href="../user-manual/actions-file.html#FILTER" target=
68 "_top">filter</a></tt> or <tt class="LITERAL"><a href=
69 "../user-manual/actions-file.html#DEANIMATE-GIFS" target=
70 "_top">deanimate-gifs</a></tt> actions may cause a perceived
71 slowdown, since the entire document needs to be buffered before
72 displaying. And on very large documents, filtering may have some
73 measurable impact. How much depends on the page size, the actual
74 definition of the filter(s), etc. See below. Most other actions
75 have little to no impact on speed.
78 Also, when filtering is enabled but zlib support isn't available,
79 compression is often disabled (see <a href=
80 "../user-manual/actions-file.html#PREVENT-COMPRESSION" target=
81 "_top">prevent-compression</a>). This can have an impact on speed
82 as well, although it's probably smaller than you might think.
83 Again, the page size, etc. will determine how much of an impact.
88 <a name="LOADINGTIMES">4.2. I notice considerable delays in page
89 requests. What's wrong?</a>
92 If you use any <tt class="LITERAL"><a href=
93 "../user-manual/actions-file.html#FILTER" target=
94 "_top">filter</a></tt> action, such as filtering banners by size,
95 web-bugs etc, or the <tt class="LITERAL"><a href=
96 "../user-manual/actions-file.html#DEANIMATE-GIFS" target=
97 "_top">deanimate-gifs</a></tt> action, the entire document must be
98 loaded into memory in order for the filtering mechanism to work,
99 and nothing is sent to the browser during this time.
102 The loading time typically does not really change much in real
103 numbers, but the feeling is different, because most browsers are
104 able to start rendering incomplete content, giving the user a
105 feeling of "it works". This effect is more noticeable on slower
106 dialup connections. Extremely large documents may have some impact
107 on the time to load the page where there is filtering being done.
108 But overall, the difference should be very minimal. If there is a
109 big impact, then probably some other situation is contributing
110 (like anti-virus software).
113 Filtering is automatically disabled for inappropriate MIME types.
114 But note that if the web server mis-reports the MIME type, then
115 content that should not be filtered, could be. <span class=
116 "APPLICATION">Privoxy</span> only knows how to differentiate
117 filterable content because of the MIME type as reported by the
118 server, or because of some configuration setting that
119 enables/disables filtering.
124 <a name="CONFIGURL">4.3. What are "http://config.privoxy.org/" and
128 <a href="http://config.privoxy.org/" target=
129 "_top">http://config.privoxy.org/</a> is the address of <span
130 class="APPLICATION">Privoxy</span>'s built-in user interface, and
131 <a href="http://p.p/" target="_top">http://p.p/</a> is a shortcut
135 Since <span class="APPLICATION">Privoxy</span> sits between your
136 web browser and the Internet, it can simply intercept requests for
137 these addresses and answer them with its built-in <span class=
138 "QUOTE">"web server"</span>.
141 This also makes for a good test for your browser configuration: If
142 entering the URL <a href="http://config.privoxy.org/" target=
143 "_top">http://config.privoxy.org/</a> takes you to a page saying
144 <span class="QUOTE">"This is Privoxy ..."</span>, everything is OK.
145 If you get a page saying <span class="QUOTE">"Privoxy is not
146 working"</span> instead, then your browser didn't use <span class=
147 "APPLICATION">Privoxy</span> for the request, hence it could not be
148 intercepted, and you have accessed the <span class="emphasis"><i
149 class="EMPHASIS">real</i></span> web site at config.privoxy.org.
152 Note that config.privoxy.org resolves to a public IP address. If
153 you use config.privoxy.org as ping or traceroute target you will
154 reach the system on the Internet (Privoxy can't intercept ICMP
155 requests). If you want to ping the system Privoxy runs on, you
156 should use its IP address or local DNS name (if it has got one).
161 <a name="NEWADS">4.4. How can I submit new ads, or report
165 Please see the <a href="contact.html">Contact section</a> for
166 various ways to interact with the developers.
171 <a name="NEWADS2">4.5. If I do submit missed ads, will they be
172 included in future updates?</a>
175 Whether such submissions are eventually included in the <tt class=
176 "FILENAME">default.action</tt> configuration file depends on how
177 significant the issue is. We of course want to address any
178 potential problem with major, high-profile sites such as <i class=
179 "CITETITLE">Google</i>, <i class="CITETITLE">Yahoo</i>, etc. Any
180 site with global or regional reach, has a good chance of being a
181 candidate. But at the other end of the spectrum are any number of
182 smaller, low-profile sites such as for local clubs or schools.
183 Since their reach and impact are much less, they are best handled
184 by inclusion in the user's <tt class="FILENAME">user.action</tt>,
185 and thus would be unlikely to be included.
190 <a name="NOONECARES">4.6. Why doesn't anyone answer my support
194 Rest assured that it has been read and considered. Why it is not
195 answered, could be for various reasons, including no one has a good
196 answer for it, no one has had time to yet investigate it
197 thoroughly, it has been reported numerous times already, or because
198 not enough information was provided to help us help you. Your
199 efforts are not wasted, and we do appreciate them.
204 <a name="IP">4.7. How can I hide my IP address?</a>
207 If you run both the browser and <span class=
208 "APPLICATION">Privoxy</span> locally, you cannot hide your IP
209 address with <span class="APPLICATION">Privoxy</span> or ultimately
210 any other software alone. The server needs to know your IP address
211 so that it knows where to send the responses back.
214 There are many publicly usable "anonymous" proxies out there, which
215 provide a further level of indirection between you and the web
219 However, these proxies are called "anonymous" because you don't
220 need to authenticate, not because they would offer any real
221 anonymity. Most of them will log your IP address and make it
222 available to the authorities in case you violate the law of the
223 country they run in. In fact you can't even rule out that some of
224 them only exist to *collect* information on (those suspicious)
225 people with a more than average preference for privacy.
228 If you want to hide your IP address from most adversaries, you
229 should consider chaining <span class="APPLICATION">Privoxy</span>
230 with <a href="https://www.torproject.org/" target="_top">Tor</a>.
231 The configuration details can be found in <a href="#TOR" target=
232 "_top">How do I use <span class="APPLICATION">Privoxy</span>
233 together with <span class="APPLICATION">Tor</span> section</a> just
239 <a name="ANONFORSURE">4.8. Can Privoxy guarantee I am
243 No. Your chances of remaining anonymous are improved, but unless
244 you <a href="#TOR" target="_top">chain <span class=
245 "APPLICATION">Privoxy</span> with <span class=
246 "APPLICATION">Tor</span></a> or a similar proxy and know what
247 you're doing when it comes to configuring the rest of your system,
248 you should assume that everything you do on the Web can be traced
252 <span class="APPLICATION">Privoxy</span> can remove various
253 information about you, and allows <span class="emphasis"><i class=
254 "EMPHASIS">you</i></span> more freedom to decide which sites you
255 can trust, and what details you want to reveal. But it neither
256 hides your IP address, nor can it guarantee that the rest of the
257 system behaves correctly. There are several possibilities how a web
258 sites can find out who you are, even if you are using a strict
259 <span class="APPLICATION">Privoxy</span> configuration and chained
260 it with <span class="APPLICATION">Tor</span>.
263 Most of <span class="APPLICATION">Privoxy's</span>
264 privacy-enhancing features can be easily subverted by an insecure
265 browser configuration, therefore you should use a browser that can
266 be configured to only execute code from trusted sites, and be
267 careful which sites you trust. For example there is no point in
268 having <span class="APPLICATION">Privoxy</span> modify the
269 User-Agent header, if websites can get all the information they
270 want through JavaScript, ActiveX, Flash, Java etc.
273 A few browsers disclose the user's email address in certain
274 situations, such as when transferring a file by FTP. <span class=
275 "APPLICATION">Privoxy</span> does not filter FTP. If you need this
276 feature, or are concerned about the mail handler of your browser
277 disclosing your email address, you might consider products such as
278 <span class="APPLICATION">NSClean</span>.
281 Browsers available only as binaries could use non-standard headers
282 to give out any information they can have access to: see the
283 manufacturer's license agreement. It's impossible to anticipate and
284 prevent every breach of privacy that might occur. The
285 professionally paranoid prefer browsers available as source code,
286 because anticipating their behavior is easier. Trust the source,
292 <a name="PROXYTEST">4.9. A test site says I am not using a
296 Good! Actually, they are probably testing for some other kinds of
297 proxies. Hiding yourself completely would require additional steps.
302 <a name="TOR">4.10. How do I use Privoxy together with Tor?</a>
305 Before you configure <span class="APPLICATION">Privoxy</span> to
306 use <a href="https://www.torproject.org/" target="_top">Tor</a>,
307 please follow the <i class="CITETITLE">User Manual</i> chapters <a
308 href="../user-manual/installation.html" target="_top">2.
309 Installation</a> and <a href="../user-manual/startup.html" target=
310 "_top">5. Startup</a> to make sure <span class=
311 "APPLICATION">Privoxy</span> itself is setup correctly.
314 If it is, refer to <a href=
315 "https://www.torproject.org/documentation.html" target="_top">Tor's
316 extensive documentation</a> to learn how to install <span class=
317 "APPLICATION">Tor</span>, and make sure <span class=
318 "APPLICATION">Tor</span>'s logfile says that <span class=
319 "QUOTE">"Tor has successfully opened a circuit"</span> and it <span
320 class="QUOTE">"looks like client functionality is working"</span>.
323 If either <span class="APPLICATION">Tor</span> or <span class=
324 "APPLICATION">Privoxy</span> isn't working, their combination most
325 likely will neither. Testing them on their own will also help you
326 to direct problem reports to the right audience. If <span class=
327 "APPLICATION">Privoxy</span> isn't working, don't bother the <span
328 class="APPLICATION">Tor</span> developers. If <span class=
329 "APPLICATION">Tor</span> isn't working, don't send bug reports to
330 the <span class="APPLICATION">Privoxy</span> Team.
333 If you verified that <span class="APPLICATION">Privoxy</span> and
334 <span class="APPLICATION">Tor</span> are working, it is time to
335 connect them. As far as <span class="APPLICATION">Privoxy</span> is
336 concerned, <span class="APPLICATION">Tor</span> is just another
337 proxy that can be reached by socks4, socks4a and socks5. Most
338 likely you are interested in <span class="APPLICATION">Tor</span>
339 to increase your anonymity level, therefore you should use socks5,
340 to make sure DNS requests are done through <span class=
341 "APPLICATION">Tor</span> and thus invisible to your local network.
342 Using socks4a would work too, but with socks5 you get more precise
346 <span class="APPLICATION">Privoxy's</span> <a href=
347 "../user-manual/config.html" target="_top">main configuration
348 file</a> is already prepared for <span class=
349 "APPLICATION">Tor</span>, if you are using a default <span class=
350 "APPLICATION">Tor</span> configuration and run it on the same
351 system as <span class="APPLICATION">Privoxy</span>, you just have
352 to edit the <a href="../user-manual/config.html#FORWARDING" target=
353 "_top">forwarding section</a> and uncomment the line:
357 <table border="0" bgcolor="#E0E0E0" width="100%">
361 # forward-socks5t / 127.0.0.1:9050 .
368 Note that if you got Tor through one of the bundles, you may have
369 to change the port from 9050 to 9150 (or even another one). For
370 details, please check the documentation on the <a href=
371 "https://torproject.org/" target="_top">Tor website</a>.
374 This is enough to reach the Internet, but additionally you might
375 want to uncomment the following forward rules, to make sure your
376 local network is still reachable through Privoxy:
380 <table border="0" bgcolor="#E0E0E0" width="100%">
384 # forward 192.168.*.*/ .
385 # forward 10.*.*.*/ .
386 # forward 127.*.*.*/ .
393 Unencrypted connections to systems in these address ranges will be
394 as (un)secure as the local network is, but the alternative is that
395 your browser can't reach the network at all. Then again, that may
396 actually be desired and if you don't know for sure that your
397 browser has to be able to reach the local network, there's no
401 If you want your browser to be able to reach servers in your local
402 network by using their names, you will need additional exceptions
407 <table border="0" bgcolor="#E0E0E0" width="100%">
411 # forward localhost/ .
418 Save the modified configuration file and open <a href=
419 "http://config.privoxy.org/show-status" target=
420 "_top">http://config.privoxy.org/show-status</a> in your browser,
421 confirm that <span class="APPLICATION">Privoxy</span> has reloaded
422 its configuration and that there are no other forward lines, unless
423 you know that you need them. If everything looks good, refer to <a
425 "https://wiki.torproject.org/noreply/TheOnionRouter/TorFAQ#IsMyConnectionPrivate"
426 target="_top">Tor Faq 4.2</a> to learn how to verify that you are
427 really using <span class="APPLICATION">Tor</span>.
430 Afterward, please take the time to at least skim through the rest
431 of <span class="APPLICATION">Tor's</span> documentation. Make sure
432 you understand what <span class="APPLICATION">Tor</span> does, why
433 it is no replacement for application level security, and why you
434 probably don't want to use it for unencrypted logins.
439 <a name="SITEBREAK">4.11. Might some things break because header
440 information or content is being altered?</a>
443 Definitely. It is common for sites to use browser type, browser
444 version, HTTP header content, and various other techniques in order
445 to dynamically decide what to display and how to display it. What
446 you see, and what I see, might be very different. There are many,
447 many ways that this can be handled, so having hard and fast rules,
451 The <span class="QUOTE">"User-Agent"</span> is sometimes used in
452 this way to identify the browser, and adjust content accordingly.
455 Also, different browsers use different encodings of non-English
456 characters, certain web servers convert pages on-the-fly according
457 to the User Agent header. Giving a <span class="QUOTE">"User
458 Agent"</span> with the wrong operating system or browser
459 manufacturer causes some sites in these languages to be garbled;
460 Surfers to Eastern European sites should change it to something
461 closer. And then some page access counters work by looking at the
462 <span class="QUOTE">"Referer"</span> header; they may fail or break
463 if unavailable. The weather maps of Intellicast have been blocked
464 by their server when no <span class="QUOTE">"Referer"</span> or
465 cookie is provided, is another example. (But you can forge both
466 headers without giving information away). There are many other ways
467 things can go wrong when trying to fool a web server. The results
468 of which could inadvertently cause pages to load incorrectly,
469 partially, or even not at all. And there may be no obvious clues as
470 to just what went wrong, or why. Nowhere will there be a message
471 that says <span class="QUOTE">"<span class="emphasis"><i class=
472 "EMPHASIS">Turn off <tt class="LITERAL">fast-redirects</tt> or
473 else!</i></span> "</span>
476 Similar thoughts apply to modifying JavaScript, and, to a lesser
477 degree, HTML elements.
480 If you have problems with a site, you will have to adjust your
481 configuration accordingly. Cookies are probably the most likely
482 adjustment that may be required, but by no means the only one.
487 <a name="CACHING">4.12. Can Privoxy act as a <span class=
488 "QUOTE">"caching"</span> proxy to speed up web browsing?</a>
491 No, it does not have this ability at all. You want something like
492 <a href="http://www.squid-cache.org/" target="_top">Squid</a> or <a
493 href="http://www.pps.jussieu.fr/~jch/software/polipo/" target=
494 "_top">Polipo</a> for this. And, yes, before you ask, <span class=
495 "APPLICATION">Privoxy</span> can co-exist with other kinds of
496 proxies like <span class="APPLICATION">Squid</span>. See the <a
497 href="../user-manual/config.html#FORWARDING" target=
498 "_top">forwarding chapter</a> in the <a href=
499 "../user-manual/index.html" target="_top">user manual</a> for
505 <a name="FIREWALL">4.13. What about as a firewall? Can Privoxy
509 Not in the way you mean, or in the way some firewall vendors claim
510 they can. <span class="APPLICATION">Privoxy</span> can help protect
511 your privacy, but can't protect your system from intrusion
512 attempts. It is, of course, perfectly possible to use <span class=
513 "emphasis"><i class="EMPHASIS">both</i></span>.
518 <a name="WASTED">4.14. I have large empty spaces / a checkerboard
519 pattern now where ads used to be. Why?</a>
522 It is technically possible to eliminate banners and ads in a way
523 that frees their allocated page space. This could easily be done by
524 blocking with <span class="APPLICATION">Privoxy's</span> filters,
525 and eliminating the <span class="emphasis"><i class=
526 "EMPHASIS">entire</i></span> image references from the HTML page
530 But, this would consume considerably more CPU resources (IOW, slow
531 things down), would likely destroy the layout of some web pages
532 which rely on the banners utilizing a certain amount of page space,
533 and might fail in other cases, where the screen space is reserved
534 (e.g. by HTML tables for instance). Also, making ads and banners
535 disappear without any trace complicates troubleshooting, and would
536 sooner or later be problematic.
539 The better alternative is to instead let them stay, and block the
540 resulting requests for the banners themselves as is now the case.
541 This leaves either empty space, or the familiar checkerboard
545 So the developers won't support this in the default configuration,
546 but you can of course define appropriate filters yourself to
552 <a name="SSL">4.15. How can Privoxy filter Secure (HTTPS) URLs?</a>
555 Since secure HTTP connections are encrypted SSL sessions between
556 your browser and the secure site, and are meant to be reliably
557 <span class="emphasis"><i class="EMPHASIS">secure</i></span>, there
558 is little that <span class="APPLICATION">Privoxy</span> can do but
559 hand the raw gibberish data though from one end to the other
563 The only exception to this is blocking by host patterns, as the
564 client needs to tell <span class="APPLICATION">Privoxy</span> the
565 name of the remote server, so that <span class=
566 "APPLICATION">Privoxy</span> can establish the connection. If that
567 name matches a host-only pattern, the connection will be blocked.
570 As far as ad blocking is concerned, this is less of a restriction
571 than it may seem, since ad sources are often identifiable by the
572 host name, and often the banners to be placed in an encrypted page
573 come unencrypted nonetheless for efficiency reasons, which exposes
574 them to the full power of <span class=
575 "APPLICATION">Privoxy</span>'s ad blocking.
578 <span class="QUOTE">"Content cookies"</span> (those that are
579 embedded in the actual HTML or JS page content, see <tt class=
581 "../user-manual/actions-file.html#FILTER-CONTENT-COOKIES" target=
582 "_top">filter{content-cookies}</a></tt>), in an SSL transaction
583 will be impossible to block under these conditions. Fortunately,
584 this does not seem to be a very common scenario since most cookies
585 come by traditional means.
590 <a name="SECURE">4.16. Privoxy runs as a <span class=
591 "QUOTE">"server"</span>. How secure is it? Do I need to take any
592 special precautions?</a>
595 On Unix-like systems, <span class="APPLICATION">Privoxy</span> can
596 run as a non-privileged user, which is how we recommend it be run.
597 Also, by default <span class="APPLICATION">Privoxy</span> listens
598 to requests from <span class="QUOTE">"localhost"</span> only.
601 The server aspect of <span class="APPLICATION">Privoxy</span> is
602 not itself directly exposed to the Internet in this configuration.
603 If you want to have <span class="APPLICATION">Privoxy</span> serve
604 as a LAN proxy, this will have to be opened up to allow for LAN
605 requests. In this case, we'd recommend you specify only the LAN
606 gateway address, e.g. 192.168.1.1, in the main <span class=
607 "APPLICATION">Privoxy</span> configuration file and check all <a
608 href="../user-manual/config.html#ACCESS-CONTROL" target=
609 "_top">access control and security options</a>. All LAN hosts can
610 then use this as their proxy address in the browser proxy
611 configuration, but <span class="APPLICATION">Privoxy</span> will
612 not listen on any external interfaces. ACLs can be defined in
613 addition, and using a firewall is always good too. Better safe than
619 <a name="TURNOFF">4.17. Can I temporarily disable Privoxy?</a>
622 <span class="APPLICATION">Privoxy</span> doesn't have a transparent
623 proxy mode, but you can toggle off blocking and content filtering.
626 The easiest way to do that is to point your browser to the remote
627 toggle URL: <a href="http://config.privoxy.org/toggle" target=
628 "_top">http://config.privoxy.org/toggle</a>.
631 See the <a href="../user-manual/appendix.html#BOOKMARKLETS" target=
632 "_top">Bookmarklets section</a> of the <i class="CITETITLE">User
633 Manual</i> for an easy way to access this feature. Note that this
634 is a feature that may need to be enabled in the main <tt class=
635 "FILENAME">config</tt> file.
640 <a name="REALLYOFF">4.18. When <span class=
641 "QUOTE">"disabled"</span> is Privoxy totally out of the
645 No, this just means all optional filtering and actions are
646 disabled. <span class="APPLICATION">Privoxy</span> is still acting
647 as a proxy, but just doing less of the things that <span class=
648 "APPLICATION">Privoxy</span> would normally be expected to do. It
649 is still a <span class="QUOTE">"middle-man"</span> in the
650 interaction between your browser and web sites. See below to bypass
656 <a name="TURNOFF2">4.19. How can I tell Privoxy to totally ignore
660 Bypassing a proxy, or proxying based on arbitrary criteria, is
661 purely a browser configuration issue, not a <span class=
662 "APPLICATION">Privoxy</span> issue. Modern browsers typically do
663 have settings for not proxying certain sites. Check your browser's
669 <a name="CRUNCH">4.20. My logs show Privoxy <span class=
670 "QUOTE">"crunches"</span> ads, but also its own internal CGI pages.
671 What is a <span class="QUOTE">"crunch"</span>?</a>
674 A <span class="QUOTE">"crunch"</span> simply means <span class=
675 "APPLICATION">Privoxy</span> intercepted <span class="emphasis"><i
676 class="EMPHASIS">something</i></span>, nothing more. Often this is
677 indeed ads or banners, but <span class="APPLICATION">Privoxy</span>
678 uses the same mechanism for trapping requests for its own internal
679 pages. For instance, a request for <span class=
680 "APPLICATION">Privoxy's</span> configuration page at: <a href=
681 "http://config.privoxy.org" target=
682 "_top">http://config.privoxy.org</a>, is intercepted (i.e. it does
683 not go out to the 'net), and the familiar CGI configuration is
684 returned to the browser, and the log consequently will show a <span
685 class="QUOTE">"crunch"</span>.
688 Since version 3.0.7, Privoxy will also log the crunch reason. If
689 you are using an older version you might want to upgrade.
694 <a name="DOWNLOADS">4.21. Can Privoxy affect files that I download
695 from a webserver? FTP server?</a>
698 From the webserver's perspective, there is no difference between
699 viewing a document (i.e. a page), and downloading a file. The same
700 is true of <span class="APPLICATION">Privoxy</span>. If there is a
701 match for a <tt class="LITERAL"><a href=
702 "../user-manual/actions-file.html#BLOCK" target=
703 "_top">block</a></tt> pattern, it will still be blocked, and of
704 course this is obvious.
707 Filtering is potentially more of a concern since the results are
708 not always so obvious, and the effects of filtering are there
709 whether the file is simply viewed, or downloaded. And potentially
710 whether the content is some obnoxious advertisement, or Mr. Jimmy's
711 latest/greatest source code jewel. Of course, one of these
712 presumably is <span class="QUOTE">"bad"</span> content that we
713 don't want, and the other is <span class="QUOTE">"good"</span>
714 content that we do want. <span class="APPLICATION">Privoxy</span>
715 is blind to the differences, and can only distinguish <span class=
716 "QUOTE">"good from bad"</span> by the configuration parameters
717 <span class="emphasis"><i class="EMPHASIS">we</i></span> give it.
720 <span class="APPLICATION">Privoxy</span> knows the differences in
721 files according to the <span class="QUOTE">"Content Type"</span> as
722 reported by the webserver. If this is reported accurately (e.g.
723 <span class="QUOTE">"application/zip"</span> for a zip archive),
724 then <span class="APPLICATION">Privoxy</span> knows to ignore these
725 where appropriate. <span class="APPLICATION">Privoxy</span>
726 potentially can filter HTML as well as plain text documents,
727 subject to configuration parameters of course. Also, documents that
728 are of an unknown type (generally assumed to be <span class=
729 "QUOTE">"text/plain"</span>) can be filtered, as will those that
730 might be incorrectly reported by the webserver. If such a file is a
731 downloaded file that is intended to be saved to disk, then any
732 content that might have been altered by filtering, will be saved
733 too, for these (probably rare) cases.
736 Note that versions later than 3.0.2 do NOT filter document types
737 reported as <span class="QUOTE">"text/plain"</span>. Prior to this,
738 <span class="APPLICATION">Privoxy</span> did filter this document
742 In short, filtering is <span class="QUOTE">"ON"</span> if a) the
743 content type as reported by the webserver is appropriate <span
744 class="emphasis"><i class="EMPHASIS">and</i></span> b) the
745 configuration allows it (or at least does not disallow it). That's
746 it. There is no magic cookie anywhere to say this is <span class=
747 "QUOTE">"good"</span> and this is <span class="QUOTE">"bad"</span>.
748 It's the configuration that lets it all happen or not.
751 If you download text files, you probably do not want these to be
752 filtered, particularly if the content is source code, or other
753 critical content. Source code sometimes might be mistaken for
754 Javascript (i.e. the kind that might open a pop-up window). It is
755 recommended to turn off filtering for download sites (particularly
756 if the content may be plain text files and you are using version
757 3.0.2 or earlier) in your <tt class="FILENAME">user.action</tt>
758 file. And also, for any site or page where making <span class=
759 "emphasis"><i class="EMPHASIS">any</i></span> changes at all to the
760 content is to be avoided.
763 <span class="APPLICATION">Privoxy</span> does not do FTP at all,
764 only HTTP and HTTPS (SSL) protocols.
769 <a name="DOWNLOADS2">4.22. I just downloaded a Perl script, and
770 Privoxy altered it! Yikes, what is wrong!</a>
778 <a name="HOSTSFILE">4.23. Should I continue to use a <span class=
779 "QUOTE">"HOSTS"</span> file for ad-blocking?</a>
782 One time-tested technique to defeat common ads is to trick the
783 local DNS system by giving a phony IP address for the ad generator
784 in the local <tt class="FILENAME">HOSTS</tt> file, typically using
785 <tt class="LITERAL">127.0.0.1</tt>, aka <tt class=
786 "LITERAL">localhost</tt>. This effectively blocks the ad.
789 There is no reason to use this technique in conjunction with <span
790 class="APPLICATION">Privoxy</span>. <span class=
791 "APPLICATION">Privoxy</span> does essentially the same thing, much
792 more elegantly and with much more flexibility. A large <tt class=
793 "FILENAME">HOSTS</tt> file, in fact, not only duplicates effort,
794 but may get in the way and seriously slow down your system. It is
795 recommended to remove such entries from your <tt class=
796 "FILENAME">HOSTS</tt> file. If you think your hosts list is
797 neglected by <span class="APPLICATION">Privoxy's</span>
798 configuration, consider adding your list to your <tt class=
799 "FILENAME">user.action</tt> file:
803 <table border="0" bgcolor="#E0E0E0" width="100%">
810 ads.galore.example.com
819 <a name="SEEALSO">4.24. Where can I find more information about
820 Privoxy and related issues?</a>
823 Other references and sites of interest to <span class=
824 "APPLICATION">Privoxy</span> users:
832 <a href="https://www.privoxy.org/" target=
833 "_top">https://www.privoxy.org/</a>, the <span class=
834 "APPLICATION">Privoxy</span> Home page.
843 <a href="https://www.privoxy.org/faq/" target=
844 "_top">https://www.privoxy.org/faq/</a>, the <span class=
845 "APPLICATION">Privoxy</span> FAQ.
854 <a href="https://www.privoxy.org/developer-manual/" target=
855 "_top">https://www.privoxy.org/developer-manual/</a>, the
856 <span class="APPLICATION">Privoxy</span> developer manual.
865 <a href="https://sourceforge.net/projects/ijbswa/" target=
866 "_top">https://sourceforge.net/projects/ijbswa/</a>, the
867 Project Page for <span class="APPLICATION">Privoxy</span> on
868 <a href="http://sourceforge.net" target=
869 "_top">SourceForge</a>.
878 <a href="http://config.privoxy.org/" target=
879 "_top">http://config.privoxy.org/</a>, the web-based user
880 interface. <span class="APPLICATION">Privoxy</span> must be
881 running for this to work. Shortcut: <a href="http://p.p/"
882 target="_top">http://p.p/</a>
892 "https://sourceforge.net/tracker/?group_id=11118&atid=460288"
894 "_top">https://sourceforge.net/tracker/?group_id=11118&atid=460288</a>,
895 to submit <span class="QUOTE">"misses"</span> and other
896 configuration related suggestions to the developers.
905 <a href="http://www.squid-cache.org/" target=
906 "_top">http://www.squid-cache.org/</a>, a popular caching
907 proxy, which is often used together with <span class=
908 "APPLICATION">Privoxy</span>.
918 "http://www.pps.univ-paris-diderot.fr/~jch/software/polipo/"
920 "_top">http://www.pps.univ-paris-diderot.fr/~jch/software/polipo/</a>,
921 <span class="APPLICATION">Polipo</span> is a caching proxy
922 with advanced features like pipelining, multiplexing and
923 caching of partial instances. In many setups it can be used
924 as <span class="APPLICATION">Squid</span> replacement.
933 <a href="https://www.torproject.org/" target=
934 "_top">https://www.torproject.org/</a>, <span class=
935 "APPLICATION">Tor</span> can help anonymize web browsing, web
936 publishing, instant messaging, IRC, SSH, and other
945 <a name="MICROSUCK">4.25. I've noticed that Privoxy changes <span
946 class="QUOTE">"Microsoft"</span> to <span class=
947 "QUOTE">"MicroSuck"</span>! Why are you manipulating my
951 We're not. The text substitutions that you are seeing are disabled
952 in the default configuration as shipped. You have either manually
953 activated the <span class="QUOTE">"<tt class=
954 "LITERAL">fun</tt>"</span> filter which is clearly labeled <span
955 class="QUOTE">"Text replacements for subversive browsing
956 fun!"</span> or you are using an older Privoxy version and have
957 implicitly activated it by choosing the <span class=
958 "QUOTE">"Advanced"</span> profile in the web-based editor. Please
964 <a name="VALID">4.26. Does Privoxy produce <span class=
965 "QUOTE">"valid"</span> HTML (or XHTML)?</a>
968 Privoxy generates HTML in both its own <span class=
969 "QUOTE">"templates"</span>, and possibly whenever there are text
970 substitutions via a <span class="APPLICATION">Privoxy</span>
971 filter. While this should always conform to the HTML 4.01
972 specifications, it has not been validated against this or any other
978 <a name="SURPRISE-PRIVOXY">4.27. How did you manage to get Privoxy
979 on my computer without my consent?</a>
982 We didn't. We make Privoxy available for download, but we don't go
983 around installing it on other people's systems behind their back.
984 If you discover Privoxy running on your system and are sure you
985 didn't install it yourself, somebody else did. You may not even be
986 running the real Privoxy, but maybe something else that only
987 pretends to be Privoxy, or maybe something that is based on the
988 real Privoxy, but has been modified.
991 Lately there have been reports of problems with some kind of
992 "parental control" software based on Privoxy that came preinstalled
993 on certain <a href="https://sourceforge.net/p/ijbswa/bugs/813/"
994 target="_top">ASUS Netbooks</a>. The problems described are
995 inconsistent with the behaviour of official Privoxy versions, which
996 suggests that the preinstalled software may contain vendor
997 modifications that we don't know about and thus can't debug.
1000 Privoxy's <a href="copyright.html">license</a> allows vendor
1001 modifications, but the vendor has to comply with the license, which
1002 involves informing the user about the changes and to make the
1003 changes available under the same license as Privoxy itself.
1006 If you are having trouble with a modified Privoxy version, please
1007 try to talk to whoever made the modifications before reporting the
1008 problem to us. Please also try to convince whoever made the
1009 modifications to talk to us. If you think somebody gave you a
1010 modified Privoxy version without complying to the license, please
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