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43 >Privoxy Frequently Asked Questions</TH
51 HREF="installation.html"
88 >3.1. What exactly is an <SPAN
97 > utilizes the concept of <SPAN
100 HREF="../user-manual/actions-file.html#ACTIONS"
105 that are used to manipulate and control web page data.
107 HREF="../user-manual/actions-file.html"
112 HREF="../user-manual/actions-file.html#ACTIONS"
119 > could take while processing a certain
120 request, are configured. Typically, you would define a set of default actions
121 that apply globally to all URLs, then add exceptions to these defaults where needed.
122 There is a wide array of actions available that give the user a high degree
123 of control and flexibility on how to process each and every web page.</P
125 > Actions can be defined on a <A
126 HREF="../user-manual/actions-file.html#AF-PATTERNS"
130 for single URLs, whole web sites, groups or parts thereof etc. Actions can also be
131 grouped together and then applied to requests matching one or more patterns.
132 There are many possible actions that might apply to any given site. As an example,
133 if you are blocking <A
134 HREF="http://en.wikipedia.org/wiki/Browser_cookie"
138 as one of your default actions, but need to accept cookies from a given site,
139 you would need to define an exception for this site in one of your actions
140 files, preferably in <TT
154 > concept confuses me. Please list
161 > For a comprehensive discussion of the actions concept, please refer
163 HREF="../user-manual/actions-file.html"
168 HREF="../user-manual/index.html"
173 HREF="../user-manual/actions-file.html#ACTIONS"
175 >list of all actions</A
178 HREF="../user-manual/actions-file.html#ACT-EXAMPLES"
182 > to get you started.</P
190 >3.3. How are actions files configured? What is the easiest
194 > Actions files are just text files in a special syntax and can be edited
195 with a text editor. But probably the easiest way is to access
199 >'s user interface with your web browser
201 HREF="http://config.privoxy.org/"
203 >http://config.privoxy.org/</A
213 HREF="http://config.privoxy.org/show-status"
216 change the current configuration</A
218 > from the menu. Note
219 that this feature must be explicitly enabled in the main config file
221 HREF="../user-manual/config.html#ENABLE-EDIT-ACTIONS"
223 >enable-edit-actions</A
232 >3.4. There are several different <SPAN
239 > Please have a look at the <A
240 HREF="../user-manual/actions-file.html"
242 >the actions chapter</A
245 HREF="../user-manual/index.html"
248 > for a detailed explanation.</P
256 >3.5. Where can I get updated Actions Files?</A
259 > Based on your feedback and the continuing development, updates of
264 made available from time to time on the <A
265 HREF="https://sourceforge.net/project/showfiles.php?group_id=11118"
270 HREF="https://sourceforge.net/projects/ijbswa/"
276 > If you wish to receive an email notification whenever we release updates of
280 > or the actions file, <A
281 HREF="https://lists.privoxy.org/mailman/listinfo/privoxy-announce"
284 to our announce mailing list</A
285 >, privoxy-announce@lists.privoxy.org.
294 >3.6. Can I use my old config files?</A
297 > The syntax and purpose of configuration files has remained roughly the
298 same throughout the 3.x series, but backwards compatibility is not guaranteed.
299 Also each release contains updated, <SPAN
303 therefore strongly recommended to install the newer configuration files
304 and merge back your modifications.
313 >3.7. Why is the configuration so complicated?</A
319 > is in the eye of the beholder.
322 > Privoxy is currently mainly written by and for people who are already
323 familiar with the underlying concepts like regular expressions, HTTP and HTML,
324 or are willing to become familiar with them to be able to get the most
325 out of a powerful and flexible tool such as Privoxy.
328 > While everybody is expected to be able to get a Privoxy default installation
329 up and running, fine-tuning requires a certain amount of background
330 information and Privoxy's documentation mainly concentrates on the
331 Privoxy-specific parts while only providing references to the rest.
334 > If you or anyone you know has the skills, time and energy to
335 reduce the barrier of entry, please <A
336 HREF="general.html#PARTICIPATE"
347 >3.8. How can I make my Yahoo/Hotmail/Gmail account work?</A
350 > The default configuration shouldn't impact the usability of any of these services.
351 It may, however, make all <A
352 HREF="http://en.wikipedia.org/wiki/Browser_cookie"
356 temporary, so that your browser will forget your
357 login credentials in between browser sessions. If you would like not to have to log
358 in manually each time you access those websites, simply turn off all cookie handling
362 > file. An example for yahoo might
373 ># Allow all cookies for Yahoo login:
376 HREF="../user-manual/actions-file.html#CRUNCH-INCOMING-COOKIES"
378 >crunch-incoming-cookies</A
380 HREF="../user-manual/actions-file.html#CRUNCH-OUTGOING-COOKIES"
382 >crunch-outgoing-cookies</A
384 HREF="../user-manual/actions-file.html#SESSION-COOKIES-ONLY"
386 >session-cookies-only</A
388 .login.yahoo.com</PRE
393 > These kinds of sites are often quite complex and heavy with
395 HREF="http://en.wikipedia.org/wiki/Javascript"
410 HREF="../user-manual/actions-file.html#ALIASES"
424 ># Gmail is a _fragile_ site:
436 > Be sure to flush your browser's caches whenever making these kinds of
437 changes, just to make sure the changes <SPAN
443 > Make sure the domain, host and path are appropriate as well. Your browser can
444 tell you where you are specifically and you should use that information for
445 your configuration settings. Note that above it is not referenced as
449 >, which is a valid domain name.
458 >3.9. What's the difference between the
474 > is not entirely trivial. To
475 help you get started, we provide you with three different default action
479 > in the web based actions file editor at <A
480 HREF="http://config.privoxy.org/show-status"
482 >http://config.privoxy.org/show-status</A
485 HREF="../user-manual/actions-file.html"
492 > for a list of actions, and how the default
496 > Where the defaults are likely to break some sites, exceptions for
500 > sites are included, but in
501 general, the more aggressive your default settings are, the more exceptions
502 you will have to make later. New users are best to start off in
506 > setting. This is safest and will have the fewest
508 HREF="../user-manual/index.html"
515 for a more detailed discussion.</P
517 > It should be noted that the <SPAN
520 > profile (formerly known
523 >"Adventuresome"</SPAN
525 aggressive, and will make use of some of
529 > advanced features. Use at your own risk!</P
537 >3.10. Why can I change the configuration
538 with a browser? Does that not raise security issues?</A
541 > It may seem strange that regular users can edit the config files with their
542 browsers, although the whole <TT
546 belongs to the user <SPAN
549 >, with only 644 permissions.
552 > When you use the browser-based editor, <SPAN
556 itself is writing to the config files. Because
560 > is running as the user <SPAN
564 it can update its own config files.
570 > for multiple untrusted users (e.g. in
571 a LAN) or aren't entirely in control of your own browser, you will probably want
572 to make sure that the web-based editor and remote toggle features are
581 HREF="../user-manual/config.html#ENABLE-EDIT-ACTIONS"
583 >enable-edit-actions</A
592 HREF="../user-manual/config.html#ENABLE-REMOTE-TOGGLE"
594 >enable-remote-toggle</A
599 HREF="../user-manual/config.html"
601 >main configuration file</A
608 > 3.0.7 these options are disabled by default.
617 >3.11. What is the <TT
620 > file? What is a <SPAN
627 HREF="../user-manual/filter-file.html"
640 > as supplied by the developers are defined.
641 Filters are a special subset of actions that can be used to modify or
642 remove web page content or headers on the fly. Content filters can
649 > in the page source,
650 header filters can be applied to either server or client headers.
651 Regular expressions are used to accomplish this.</P
653 > There are a number of pre-defined filters to deal with common annoyances. The
654 filters are only defined here, to invoke them, you need to use the
656 HREF="../user-manual/actions-file.html#FILTER"
663 > in one of the actions files. Content filtering is automatically
664 disabled for inappropriate MIME types, but if you know better than Privoxy
665 what should or should not be filtered you can filter any content you like.</P
674 > be confused with <A
675 HREF="../user-manual/actions-file.html#BLOCK"
682 is a completely different action, and is more typically used to block ads and
685 > If you are familiar with regular expressions, and HTML, you can look at
689 > with a text editor and define
690 your own filters. This is potentially a very powerful feature, but
691 requires some expertise in both regular expressions and HTML/HTTP.
693 place any modifications to the default filters, or any new ones you create
694 in a separate file, such as <TT
698 be overwritten during upgrades.
699 The ability to define multiple filter files
703 > is a new feature as of v. 3.0.5.</P
705 > There is no GUI editor option for this part of the configuration,
706 but you can disable/enable the various pre-defined filters of the included
711 HREF="http://config.privoxy.org/show-status"
713 >web-based actions file editor</A
715 Note that the custom actions editor must be explicitly enabled in
716 the main config file (see <A
717 HREF="../user-manual/config.html#ENABLE-EDIT-ACTIONS"
719 >enable-edit-actions</A
722 > If you intend to develop your own filters, you might want to have a look at
724 HREF="https://www.fabiankeil.de/sourcecode/pft/"
726 >Privoxy-Filter-Test</A
735 >3.12. How can I set up Privoxy to act as a proxy for my
742 > only responds to requests
746 > (localhost). To have it act as a server for
747 a network, this needs to be changed in the <A
748 HREF="../user-manual/config.html"
750 >main configuration file</A
755 HREF="../user-manual/config.html#LISTEN-ADDRESS"
760 option, which may be commented out with a <SPAN
764 it is uncommented, and assign it the address of the LAN gateway interface,
765 and port number to use. Assuming your LAN address is 192.168.1.1 and you
769 > on port 8118, this line
779 > listen-address 192.168.1.1:8118</PRE
784 > Save the file, and restart <SPAN
788 all browsers on the network then to use this address and port number.</P
790 > Alternately, you can have <SPAN
794 all available interfaces:</P
803 > listen-address :8118</PRE
813 HREF="../user-manual/config.html#PERMIT-ACCESS"
817 feature to limit connections. A firewall in this situation is recommended
820 > The above steps should be the same for any TCP network, regardless of
826 > on a LAN with untrusted users,
827 we recommend that you double-check the <A
828 HREF="../user-manual/config.html#ACCESS-CONTROL"
830 >access control and security</A
840 >3.13. Instead of ads, now I get a checkerboard pattern. I don't want to see anything.</A
843 > The replacement for blocked images can be controlled with the <A
844 HREF="../user-manual/actions-file.html#SET-IMAGE-BLOCKER"
848 >set-image-blocker</TT
851 >. You have the choice of a checkerboard pattern, a transparent 1x1 GIF
855 >), or a redirect to a custom image of your choice.
856 Note that this choice only has effect for images which are blocked as images, i.e.
857 whose URLs match both a <TT
860 HREF="../user-manual/actions-file.html#HANDLE-AS-IMAGE"
874 HREF="../user-manual/actions-file.html#BLOCK"
880 > If you want to see nothing, then change the <A
881 HREF="../user-manual/actions-file.html#SET-IMAGE-BLOCKER"
885 >set-image-blocker</TT
891 >. This can be done by editing the
895 > file, or through the <A
896 HREF="http://config.privoxy.org/show-status"
898 >web-based actions file editor</A
907 >3.14. Why would anybody want to see a checkerboard pattern?</A
911 HREF="general.html#WHATSANAD"
912 >telling which image is an ad and which
914 >, is an educated guess. While we hope that the standard configuration
915 is rather smart, it will make occasional mistakes. The checkerboard image is visually
916 decent, and it shows you where images have been blocked, which can be very
917 helpful in case some navigation aid or otherwise innocent image was
918 erroneously blocked. It is recommended for new users so they can
922 > what is happening. Some people might also enjoy seeing how
923 many banners they <SPAN
937 >3.15. I see some images being replaced with text
938 instead of the checkerboard image. Why and how do I get rid of this?</A
941 > This happens when the banners are not embedded in the HTML code of the
942 page itself, but in separate HTML (sub)documents that are loaded into (i)frames
943 or (i)layers, and these external HTML documents are blocked. Being non-images
944 they get replaced by a substitute HTML page rather than a substitute image,
945 which wouldn't work out technically, since the browser expects and accepts
946 only HTML when it has requested an HTML document.</P
948 > The substitute page adapts to the available space and shows itself as a
949 miniature two-liner if loaded into small frames, or full-blown with a
950 large red "BLOCKED" banner if space allows.</P
952 > If you prefer the banners to be blocked by images, you must see to it that
953 the HTML documents in which they are embedded are not blocked. Clicking
957 > link offered in the substitute page will show
958 you which rule blocked the page. After changing the rule and un-blocking
959 the HTML documents, the browser will try to load the actual banner images
960 and the usual image blocking will (hopefully!) kick in.</P
968 >3.16. Can Privoxy run as a service
972 > Yes. Version 3.0.5 introduces full <SPAN
976 functionality. See <A
977 HREF="../user-manual/installation.html#INSTALLATION-PACK-WIN"
983 > for details on how to install and configure
989 > Earlier 3.x versions could run as a system service using <B
993 See the discussion at <A
994 HREF="https://sourceforge.net/tracker/?func=detail&atid=361118&aid=485617&group_id=11118"
996 >https://sourceforge.net/tracker/?func=detail&atid=361118&aid=485617&group_id=11118</A
998 for details, and a sample configuration.</P
1006 >3.17. How can I make Privoxy work with other proxies?</A
1009 > This can be done and is often useful to combine the benefits of
1013 > with those of a another proxy,
1014 for example to cache content.
1016 HREF="../user-manual/config.html#FORWARDING"
1018 >forwarding chapter</A
1021 HREF="../user-manual/index.html"
1025 describes how to do this. If you intend to use Privoxy with Tor,
1026 please also have a look at
1028 HREF="misc.html#TOR"
1029 >How do I use Privoxy together with Tor</A
1038 >3.18. Can I just set Privoxy to use port 80
1039 and thus avoid individual browser configuration?</A
1042 > No, its more complicated than that. This only works with special kinds
1043 of proxies known as <SPAN
1045 >"intercepting"</SPAN
1048 HREF="configuration.html#INTERCEPTING"
1058 >3.19. Can Privoxy run as a <SPAN
1060 >"transparent"</SPAN
1064 > The whole idea of Privoxy is to modify client requests
1065 and server responses in all sorts of ways and therefore
1066 it's not a transparent proxy as described in
1068 HREF="http://tools.ietf.org/html/rfc2616"
1073 > However, some people say <SPAN
1075 >"transparent proxy"</SPAN
1079 >"intercepting proxy"</SPAN
1080 >. If you are one of them,
1082 HREF="configuration.html#INTERCEPTING"
1092 >3.20. Can Privoxy run as a <SPAN
1094 >"intercepting"</SPAN
1101 > can't intercept traffic itself,
1102 but it can handle requests that where intercepted and redirected
1103 with a packet filter (like <SPAN
1110 >), as long as the <TT
1120 > header is required by HTTP/1.1 and as most
1121 web sites rely on it anyway, this limitation shouldn't be a problem.</P
1123 > Please refer to your packet filter's documentation to learn how to
1124 intercept and redirect traffic into <SPAN
1128 Afterward you just have to configure <SPAN
1133 HREF="../user-manual/config.html#ACCEPT-INTERCEPTED-REQUESTS"
1136 intercepted requests</A
1145 >3.21. How can I configure Privoxy for use with Outlook?</A
1151 > prior to Office 2007, use
1154 >Internet Explorer</SPAN
1155 > components to both render HTML,
1156 and fetch any HTTP requests that may be embedded in an HTML email. So however
1160 > configured to work with IE, this
1161 configuration should automatically be shared, at least with older version of
1162 Internet Explorer.</P
1164 > Starting with Office 2007, Microsoft is instead using the MS-Word rendering
1165 engine with Outlook. It is unknown whether this can be configured to use a
1175 >3.22. How can I have separate rules just for HTML mail?</A
1178 > The short answer is, you can't. <SPAN
1182 of knowing which particular application makes a request, so there is no way to
1183 distinguish between web pages and HTML mail.
1187 > just blindly proxies all requests. In the
1190 >Outlook Express</SPAN
1191 > (see above), OE uses
1192 IE anyway, and there is no way for <SPAN
1196 be able to distinguish between them (nor could any other proxy type application for
1199 > For a good discussion of some of the issues involved (including privacy and
1200 security issues), see
1202 HREF="https://sourceforge.net/tracker/?func=detail&atid=211118&aid=629518&group_id=11118"
1204 >https://sourceforge.net/tracker/?func=detail&atid=211118&aid=629518&group_id=11118</A
1212 NAME="SNEAKY-COOKIES"
1213 >3.23. I sometimes notice cookies sneaking through. How?</A
1217 HREF="http://en.wikipedia.org/wiki/Browser_cookie"
1221 set in several ways. The classic method is via the
1225 > HTTP header. This is straightforward, and an
1226 easy one to manipulate, such as the <SPAN
1231 HREF="../user-manual/actions-file.html#SESSION-COOKIES-ONLY"
1233 >session-cookies-only</A
1235 There is also the possibility of using
1237 HREF="http://en.wikipedia.org/wiki/Javascript"
1246 >content-cookies</TT
1248 is trickier because the syntax can vary widely, and thus requires a certain
1249 amount of guesswork. It is not realistic to catch all of these short of
1250 disabling Javascript, which would break many sites. And lastly, if the
1251 cookies are embedded in a HTTPS/SSL secure session via Javascript, they are beyond
1260 > can help manage cookies in general, can help minimize
1261 the loss of privacy posed by cookies, but can't realistically stop all
1270 >3.24. Are all cookies bad? Why?</A
1273 > No, in fact there are many beneficial uses of
1275 HREF="http://en.wikipedia.org/wiki/Browser_cookie"
1278 >. Cookies are just a
1279 method that browsers can use to store data between pages, or between browser
1280 sessions. Sometimes there is a good reason for this, and the user's life is a
1281 bit easier as a result. But there is a long history of some websites taking
1282 advantage of this layer of trust, and using the data they glean from you and
1283 your browsing habits for their own purposes, and maybe to your potential
1284 detriment. Such sites are using you and storing their data on your system.
1285 That is why the privacy conscious watch from whom those cookies come, and why
1296 HREF="http://en.wikipedia.org/wiki/Browser_cookie"
1307 NAME="ALLOW-COOKIES"
1308 >3.25. How can I allow permanent cookies for my trusted sites?</A
1311 > There are several actions that relate to cookies. The default behavior is to
1314 >"session cookies"</SPAN
1315 >, which means the cookies only last
1316 for the current browser session. This eliminates most kinds of abuse related
1317 to cookies. But there may be cases where you want cookies to last.</P
1319 > To disable all cookie actions, so that cookies are allowed unrestricted,
1320 both in and out, for <TT
1332 > { -crunch-incoming-cookies -crunch-outgoing-cookies -session-cookies-only -filter{content-cookies} }
1338 > Place the above in <TT
1341 >. Note that some of these may
1342 be off by default anyway, so this might be redundant, but there is no harm
1343 being explicit in what you want to happen. <TT
1347 includes an alias for this situation, called
1350 >allow-all-cookies</TT
1359 >3.26. Can I have separate configurations for different users?</A
1362 > Each instance of <SPAN
1366 configuration, including such attributes as the TCP port that it listens on.
1367 What you can do is run multiple instances of <SPAN
1373 HREF="../user-manual/config.html#LISTEN-ADDRESS"
1377 configuration setting, and configuration path, and then
1378 each of these can have their own configurations. Think of it as per-port
1381 > Simple enough for a few users, but for large installations, consider having
1382 groups of users that might share like configurations.</P
1390 >3.27. Can I set-up Privoxy as a whitelist of
1397 > Sure. There are a couple of things you can do for simple white-listing.
1398 Here's one real easy one:</P
1407 > ############################################################
1409 ############################################################
1411 HREF="../user-manual/actions-file.html#BLOCK"
1415 / # Block *all* URLs
1417 ############################################################
1419 ############################################################
1421 HREF="../user-manual/actions-file.html#BLOCK"
1427 games.example.com</PRE
1432 > This allows access to only those three sites by first blocking all URLs, and
1433 then subsequently allowing three specific exceptions.</P
1435 > Another approach is <SPAN
1442 > concept, which incorporates the notion of
1445 >"trusted referrers"</SPAN
1447 HREF="../user-manual/config.html#TRUSTFILE"
1449 >Trust documentation</A
1453 > These are fairly simple approaches and are not completely foolproof. There
1454 are various other configuration options that should be disabled (described
1455 elsewhere here and in <A
1456 HREF="../user-manual/"
1460 so that users can't modify their own configuration and easily circumvent the
1469 >3.28. How can I turn off ad-blocking?</A
1472 > Ad blocking is achieved through a complex application of various <SPAN
1477 HREF="../user-manual/actions-file.html"
1481 actions are deployed against simple images, banners, flash animations,
1482 text pages, JavaScript, pop-ups and pop-unders, etc., so its not as simple as
1483 just turning one or two actions off. The various actions that make up
1487 > ad blocking are hard-coded into the default configuration files. It
1488 has been assumed that everyone using <SPAN
1491 > is interested in this
1495 > If you want to do without this, there are several approaches you can take:
1496 You can manually undo the many block rules in
1500 >. Or even easier, just create your own
1504 > file from scratch without the many ad
1505 blocking rules, and corresponding exceptions. Or lastly, if you are not
1506 concerned about the additional blocks that are done for privacy reasons, you
1507 can very easily over-ride <SPAN
1514 following very simple rule in your <TT
1527 > # Unblock everybody, everywhere
1529 HREF="../user-manual/actions-file.html#BLOCK"
1533 / # UN-Block *all* URLs</PRE
1538 > Or even a more comprehensive reversing of various ad related actions:</P
1547 > # Unblock everybody, everywhere, and turn off appropriate filtering, etc
1549 HREF="../user-manual/actions-file.html#BLOCK"
1554 HREF="../user-manual/actions-file.html#FILTER-BANNERS-BY-SIZE"
1556 >-filter{banners-by-size}</A
1559 HREF="../user-manual/actions-file.html#FILTER-BANNERS-BY-LINK"
1561 >-filter{banners-by-link}</A
1568 / # UN-Block *all* URLs and allow ads</PRE
1576 > in this compound statement,
1581 HREF="../user-manual/actions-file.html#ALIASES"
1585 various pop-up blocking features.</P
1593 >3.29. How can I have custom template pages, like the
1609 > are specialized text files utilized by
1613 > for various purposes and can easily be modified using any text
1614 editor. All the template pages are installed in a sub-directory appropriately
1618 >. Knowing something about HTML syntax
1619 will of course be helpful.</P
1621 > Be forewarned that the default templates are subject to being overwritten
1622 during upgrades. You can, however, create completely new templates,
1623 place them in another directory and specify the alternate path in the main
1627 >. For details, have a look at the <A
1628 HREF="../user-manual/config.html#TEMPLDIR"
1639 >3.30. How can I remove the <SPAN
1641 >"Go There Anyway"</SPAN
1652 > There is more than one way to do it (although Perl is not involved).</P
1654 > Editing the BLOCKED template page (see above) may dissuade some users, but
1655 this method is easily circumvented. Where you need this level of control, you
1656 might want to build <SPAN
1659 > from source, and disable various features that are
1660 available as compile-time options. You should
1664 > the sources as follows:</P
1673 > ./configure --disable-toggle --disable-editor --disable-force</PRE
1678 > This will create an executable with hard-coded security features so that
1682 > does not allow easy bypassing of blocked sites, or changing the
1683 current configuration via any connected user's web browser.</P
1685 > Finally, all of these features can also be toggled on/off via options in
1690 HREF="../user-manual/config.html#ACCESS-CONTROL"
1694 means you don't have to recompile anything.</P
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