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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 > Three actions files
240 are being included by the developers, to be used for
241 different purposes: These are
249 which is actively maintained by the <SPAN
253 developers and typically sets the default policies, <TT
257 where users are encouraged to make their private customizations.
259 HREF="../user-manual/actions-file.html"
261 >the actions chapter</A
264 HREF="../user-manual/index.html"
268 detailed explanation.</P
270 > Earlier versions included three different versions of the
274 > file. The new scheme allows for
275 greater flexibility of local configuration, and for browser based
276 selection of pre-defined <SPAN
278 >"aggressiveness"</SPAN
287 >3.5. Where can I get updated Actions Files?</A
290 > Based on your feedback and the continuing development, updates of
295 made available from time to time on the <A
296 HREF="http://sourceforge.net/project/showfiles.php?group_id=11118"
301 HREF="http://sf.net/projects/ijbswa/"
307 > If you wish to receive an email notification whenever we release updates of
311 > or the actions file, <A
312 HREF="http://lists.sourceforge.net/lists/listinfo/ijbswa-announce/"
315 to our announce mailing list</A
316 >, ijbswa-announce@lists.sourceforge.net.
325 >3.6. Can I use my old config files?</A
328 > The syntax and purpose of configuration files has remained roughly the
329 same throughout the 3.x series, but backwards compatibility is not guaranteed.
330 Also each release contains updated, <SPAN
334 therefore strongly recommended to install the newer configuration files
335 and merge back your modifications.
344 >3.7. Why is the configuration so complicated?</A
350 > is in the eye of the beholder. Those that are
351 familiar with some of the underlying concepts, such as regular expression
352 syntax, take to it like a fish takes to water. Also, software that tries
355 >"user friendly"</SPAN
356 >, often lacks sophistication and
357 flexibility. There is always that trade-off there between power vs.
358 easy-of-use. Furthermore, anyone is welcome to contribute ideas and
359 implementations to enhance <SPAN
371 >3.8. How can I make my Yahoo/Hotmail/Gmail account work?</A
374 > The default configuration shouldn't impact the usability of any of these services.
375 It may, however, make all <A
376 HREF="http://en.wikipedia.org/wiki/Browser_cookie"
380 temporary, so that your browser will forget your
381 login credentials in between browser sessions. If you would like not to have to log
382 in manually each time you access those websites, simply turn off all cookie handling
386 > file. An example for yahoo might
398 ># Allow all cookies for Yahoo login:
401 HREF="../user-manual/actions-file.html#CRUNCH-INCOMING-COOKIES"
403 >crunch-incoming-cookies</A
405 HREF="../user-manual/actions-file.html#CRUNCH-OUTGOING-COOKIES"
407 >crunch-outgoing-cookies</A
409 HREF="../user-manual/actions-file.html#SESSION-COOKIES-ONLY"
411 >session-cookies-only</A
413 .login.yahoo.com</PRE
420 > These kinds of sites are often quite complex and heavy with
422 HREF="http://en.wikipedia.org/wiki/Javascript"
437 HREF="../user-manual/actions-file.html#ALIASES"
452 ># Gmail is a _fragile_ site:
466 > Be sure to flush your browser's caches whenever making these kinds of
467 changes, just to make sure the changes <SPAN
473 > Make sure the domain, host and path are appropriate as well. Your browser can
474 tell you where you are specifically and you should use that information for
475 your configuration settings. Note that above it is not referenced as
479 >, which is a valid domain name.
488 >3.9. What's the difference between the
504 > is not entirely trivial. To
505 help you get started, we provide you with three different default action
509 > in the web based actions file editor at <A
510 HREF="http://config.privoxy.org/show-status"
512 >http://config.privoxy.org/show-status</A
515 HREF="../user-manual/actions-file.html"
522 > for a list of actions, and how the default
526 > Where the defaults are likely to break some sites, exceptions for
530 > sites are included, but in
531 general, the more aggressive your default settings are, the more exceptions
532 you will have to make later. New users are best to start off in
536 > setting. This is safest and will have the fewest
538 HREF="../user-manual/index.html"
545 for a more detailed discussion.</P
547 > It should be noted that the <SPAN
550 > profile (formerly known
553 >"Adventuresome"</SPAN
555 aggressive, and will make use of some of
559 > advanced features. Use at your own risk!</P
567 >3.10. Why can I change the configuration
568 with a browser? Does that not raise security issues?</A
571 > It may seem strange that regular users can edit the config files with their
572 browsers, although the whole <TT
576 belongs to the user <SPAN
579 >, with only 644 permissions.
582 > When you use the browser-based editor, <SPAN
586 itself is writing to the config files. Because
590 > is running as the user <SPAN
594 it can update its own config files.
600 > for multiple untrusted users (e.g. in
601 a LAN) or aren't entirely in control of your own browser, you will probably want
602 to make sure that the the web-based editor and remote toggle features are
611 HREF="../user-manual/config.html#ENABLE-EDIT-ACTIONS"
613 >enable-edit-actions</A
622 HREF="../user-manual/config.html#ENABLE-REMOTE-TOGGLE"
624 >enable-remote-toggle</A
629 HREF="../user-manual/config.html"
631 >main configuration file</A
638 > 3.0.7 these options are disabled by default.
647 >3.11. What is the <TT
650 > file? What is a <SPAN
657 HREF="../user-manual/filter-file.html"
670 > as supplied by the developers are defined.
671 Filters are a special subset of actions that can be used to modify or
672 remove web page content or headers on the fly. Content filters can
679 > in the page source,
680 header filters can be applied to either server or client headers.
681 Regular expressions are used to accomplish this.</P
683 > There are a number of pre-defined filters to deal with common annoyances. The
684 filters are only defined here, to invoke them, you need to use the
686 HREF="../user-manual/actions-file.html#FILTER"
693 > in one of the actions files. Content filtering is automatically
694 disabled for inappropriate MIME types, but if you now better than Privoxy
695 what should or should not be filtered you can filter any content you like.</P
704 > be confused with <A
705 HREF="../user-manual/actions-file.html#BLOCK"
712 is a completely different action, and is more typically used to block ads and
715 > If you are familiar with regular expressions, and HTML, you can look at
719 > with a text editor and define
720 your own filters. This is potentially a very powerful feature, but
721 requires some expertise in both regular expressions and HTML/HTTP.
723 place any modifications to the default filters, or any new ones you create
724 in a separate file, such as <TT
728 be overwritten during upgrades.
729 The ability to define multiple filter files
733 > is a new feature as of v. 3.0.5.</P
735 > There is no GUI editor option for this part of the configuration,
736 but you can disable/enable the various pre-defined filters of the included
741 HREF="http://config.privoxy.org/show-status"
743 >web-based actions file editor</A
745 Note that the custom actions editor must be explicitly enabled in
746 the main config file (see <A
747 HREF="../user-manual/config.html#ENABLE-EDIT-ACTIONS"
749 >enable-edit-actions</A
752 > If you intend to develop your own filters, you might want to have a look at
754 HREF="http://www.fabiankeil.de/sourcecode/pft/"
756 >Privoxy-Filter-Test</A
765 >3.12. How can I set up Privoxy to act as a proxy for my
772 > only responds to requests
776 > (localhost). To have it act as a server for
777 a network, this needs to be changed in the <A
778 HREF="../user-manual/config.html"
780 >main configuration file</A
785 HREF="../user-manual/config.html#LISTEN-ADDRESS"
790 option, which may be commented out with a <SPAN
794 it is uncommented, and assign it the address of the LAN gateway interface,
795 and port number to use. Assuming your LAN address is 192.168.1.1 and you
799 > on port 8118, this line
810 > listen-address 192.168.1.1:8118</PRE
816 > Save the file, and restart <SPAN
820 all browsers on the network then to use this address and port number.</P
822 > Alternately, you can have <SPAN
826 all available interfaces:</P
836 > listen-address :8118</PRE
847 HREF="../user-manual/config.html#PERMIT-ACCESS"
851 feature to limit connections. A firewall in this situation is recommended
854 > The above steps should be the same for any TCP network, regardless of
860 > on a LAN with untrusted users,
861 we recommend that you double-check the <A
862 HREF="../user-manual/config.html#ACCESS-CONTROL"
864 >access control and security</A
874 >3.13. Instead of ads, now I get a checkerboard pattern. I don't want to see anything.</A
877 > The replacement for blocked images can be controlled with the <A
878 HREF="../user-manual/actions-file.html#SET-IMAGE-BLOCKER"
882 >set-image-blocker</TT
885 >. You have the choice of a checkerboard pattern, a transparent 1x1 GIF
889 >), or a redirect to a custom image of your choice.
890 Note that this choice only has effect for images which are blocked as images, i.e.
891 whose URLs match both a <TT
894 HREF="../user-manual/actions-file.html#HANDLE-AS-IMAGE"
908 HREF="../user-manual/actions-file.html#BLOCK"
914 > If you want to see nothing, then change the <A
915 HREF="../user-manual/actions-file.html#SET-IMAGE-BLOCKER"
919 >set-image-blocker</TT
925 >. This can be done by editing the
929 > file, or through the <A
930 HREF="http://config.privoxy.org/show-status"
932 >web-based actions file editor</A
941 >3.14. Why would anybody want to see a checkerboard pattern?</A
945 HREF="general.html#WHATSANAD"
946 >telling which image is an ad and which
948 >, is an educated guess. While we hope that the standard configuration
949 is rather smart, it will make occasional mistakes. The checkerboard image is visually
950 decent, and it shows you where images have been blocked, which can be very
951 helpful in case some navigation aid or otherwise innocent image was
952 erroneously blocked. It is recommended for new users so they can
956 > what is happening. Some people might also enjoy seeing how
957 many banners they <SPAN
971 >3.15. I see some images being replaced with text
972 instead of the checkerboard image. Why and how do I get rid of this?</A
975 > This happens when the banners are not embedded in the HTML code of the
976 page itself, but in separate HTML (sub)documents that are loaded into (i)frames
977 or (i)layers, and these external HTML documents are blocked. Being non-images
978 they get replaced by a substitute HTML page rather than a substitute image,
979 which wouldn't work out technically, since the browser expects and accepts
980 only HTML when it has requested an HTML document. </P
982 > The substitute page adapts to the available space and shows itself as a
983 miniature two-liner if loaded into small frames, or full-blown with a
984 large red "BLOCKED" banner if space allows.</P
986 > If you prefer the banners to be blocked by images, you must see to it that
987 the HTML documents in which they are embedded are not blocked. Clicking
991 > link offered in the substitute page will show
992 you which rule blocked the page. After changing the rule and un-blocking
993 the HTML documents, the browser will try to load the actual banner images
994 and the usual image blocking will (hopefully!) kick in.</P
1002 >3.16. Can Privoxy run as a service
1006 > Yes. Version 3.0.5 introduces full <SPAN
1010 functionality. See <A
1011 HREF="../user-manual/installation.html#installation-pack-win"
1017 > for details on how to install and configure
1023 > Earlier 3.x versions could run as a system service using <B
1027 See the discussion at <A
1028 HREF="http://sourceforge.net/tracker/?func=detail&atid=361118&aid=485617&group_id=11118"
1030 >http://sourceforge.net/tracker/?func=detail&atid=361118&aid=485617&group_id=11118</A
1032 for details, and a sample configuration.</P
1040 >3.17. How can I make Privoxy work with other
1041 proxies like Squid or Tor?</A
1044 > This can be done and is often useful to combine the benefits of
1048 > with those of a another proxy.
1050 HREF="../user-manual/config.html#FORWARDING"
1052 >forwarding chapter</A
1055 HREF="../user-manual/index.html"
1059 describes how to do this, and the <A
1060 HREF="misc.html#TOR"
1061 > How do I use Privoxy together with
1071 >3.18. Can I just set Privoxy to use port 80
1072 and thus avoid individual browser configuration?</A
1075 > No, its more complicated than that. This only works with special kinds
1076 of proxies known as <SPAN
1078 >"intercepting"</SPAN
1079 > proxies (see below).</P
1087 >3.19. Can Privoxy run as a <SPAN
1089 >"transparent"</SPAN
1093 > The whole idea of Privoxy is to modify client requests
1094 and server responses in all sorts of ways and therefore
1095 it's not a transparent proxy as described in
1097 HREF="http://tools.ietf.org/html/rfc2616"
1102 > However, some people say <SPAN
1104 >"transparent proxy"</SPAN
1108 >"intercepting proxy"</SPAN
1109 >. If you are one of them,
1111 HREF="#intercepting"
1122 >3.20. Can Privoxy run as a <SPAN
1124 >"intercepting"</SPAN
1131 > can't intercept traffic itself,
1132 but it can handle requests that where intercepted and redirected
1133 with a packet filter (like <SPAN
1140 >), as long as the <TT
1150 > header is required by HTTP/1.1 and as most
1151 web sites rely on it anyway, this limitation shouldn't be a problem.</P
1153 > Please refer to your packet filter's documentation to learn how to
1154 intercept and redirect traffic into <SPAN
1158 Afterward you just have to configure <SPAN
1163 HREF="../user-manual/config.html#ACCEPT-INTERCEPTED-REQUESTS"
1166 intercepted requests</A
1175 >3.21. How can I configure Privoxy for use with Outlook
1181 >Outlook Express</SPAN
1184 >Internet Explorer</SPAN
1186 components to both render HTML, and fetch any HTTP requests that may be embedded in an HTML email.
1187 So however you have <SPAN
1190 > configured to work
1191 with IE, this configuration should automatically be shared.</P
1199 >3.22. How can I have separate rules just for HTML mail?</A
1202 > The short answer is, you can't. <SPAN
1206 of knowing which particular application makes a request, so there is no way to
1207 distinguish between web pages and HTML mail.
1211 > just blindly proxies all requests. In the
1214 >Outlook Express</SPAN
1215 > (see above), OE uses
1216 IE anyway, and there is no way for <SPAN
1220 be able to distinguish between them (nor could any other proxy type application for
1223 > For a good discussion of some of the issues involved (including privacy and
1224 security issues), see
1226 HREF="http://sourceforge.net/tracker/?func=detail&atid=211118&aid=629518&group_id=11118"
1228 >http://sourceforge.net/tracker/?func=detail&atid=211118&aid=629518&group_id=11118</A
1236 NAME="SNEAKY-COOKIES"
1237 >3.23. I sometimes notice cookies sneaking through. How?</A
1241 HREF="http://en.wikipedia.org/wiki/Browser_cookie"
1245 set in several ways. The classic method is via the
1249 > HTTP header. This is straightforward, and an
1250 easy one to manipulate, such as the <SPAN
1255 HREF="../user-manual/actions-file.html#SESSION-COOKIES-ONLY"
1257 >session-cookies-only</A
1259 There is also the possibility of using
1261 HREF="http://en.wikipedia.org/wiki/Javascript"
1270 >content-cookies</TT
1272 is trickier because the syntax can vary widely, and thus requires a certain
1273 amount of guesswork. It is not realistic to catch all of these short of
1274 disabling Javascript, which would break many sites. And lastly, if the
1275 cookies are embedded in a HTTPS/SSL secure session via Javascript, they are beyond
1284 > can help manage cookies in general, can help minimize
1285 the loss of privacy posed by cookies, but can't realistically stop all
1294 >3.24. Are all cookies bad? Why?</A
1297 > No, in fact there are many beneficial uses of
1299 HREF="http://en.wikipedia.org/wiki/Browser_cookie"
1302 >. Cookies are just a
1303 method that browsers can use to store data between pages, or between browser
1304 sessions. Sometimes there is a good reason for this, and the user's life is a
1305 bit easier as a result. But there is a long history of some websites taking
1306 advantage of this layer of trust, and using the data they glean from you and
1307 your browsing habits for their own purposes, and maybe to your potential
1308 detriment. Such sites are using you and storing their data on your system.
1309 That is why the privacy conscious watch from whom those cookies come, and why
1320 HREF="http://en.wikipedia.org/wiki/Browser_cookie"
1331 NAME="ALLOW-COOKIES"
1332 >3.25. How can I allow permanent cookies for my trusted sites?</A
1335 > There are several actions that relate to cookies. The default behavior is to
1338 >"session cookies"</SPAN
1339 >, which means the cookies only last
1340 for the current browser session. This eliminates most kinds of abuse related
1341 to cookies. But there may be cases where you want cookies to last.</P
1343 > To disable all cookie actions, so that cookies are allowed unrestricted,
1344 both in and out, for <TT
1357 > { -crunch-incoming-cookies -crunch-outgoing-cookies -session-cookies-only -filter{content-cookies} }
1364 > Place the above in <TT
1367 >. Note that some of these may
1368 be off by default anyway, so this might be redundant, but there is no harm
1369 being explicit in what you want to happen. <TT
1373 includes an alias for this situation, called
1376 >allow-all-cookies</TT
1385 >3.26. Can I have separate configurations for different users?</A
1388 > Each instance of <SPAN
1392 configuration, including such attributes as the TCP port that it listens on.
1393 What you can do is run multiple instances of <SPAN
1399 HREF="../user-manual/config.html#LISTEN-ADDRESS"
1403 configuration setting, and configuration path, and then
1404 each of these can have their own configurations. Think of it as per-port
1408 Simple enough for a few users, but for large installations, consider having
1409 groups of users that might share like configurations.</P
1417 >3.27. Can I set-up Privoxy as a whitelist of
1424 > Sure. There are a couple of things you can do for simple white-listing.
1425 Here's one real easy one:</P
1434 > ############################################################
1436 ############################################################
1438 HREF="../user-manual/actions-file.html#BLOCK"
1442 / # Block *all* URLs
1444 ############################################################
1446 ############################################################
1448 HREF="../user-manual/actions-file.html#BLOCK"
1454 games.example.com</PRE
1459 > This allows access to only those three sites by first blocking all URLs, and
1460 then subsequently allowing three specific exceptions.</P
1462 > Another approach is <SPAN
1469 > concept, which incorporates the notion of
1472 >"trusted referrers"</SPAN
1474 HREF="../user-manual/config.html#TRUSTFILE"
1476 >Trust documentation</A
1480 > These are fairly simple approaches and are not completely foolproof. There
1481 are various other configuration options that should be disabled (described
1482 elsewhere here and in <A
1483 HREF="../user-manual/"
1487 so that users can't modify their own configuration and easily circumvent the
1496 >3.28. How can I turn off ad-blocking?</A
1499 > Ad blocking is achieved through a complex application of various <SPAN
1504 HREF="../user-manual/actions-file.html"
1508 actions are deployed against simple images, banners, flash animations,
1509 text pages, JavaScript, pop-ups and pop-unders, etc., so its not as simple as
1510 just turning one or two actions off. The various actions that make up
1514 > ad blocking are hard-coded into the default configuration files. It
1515 has been assumed that everyone using <SPAN
1518 > is interested in this
1522 > If you want to do without this, there are several approaches you can take:
1523 You can manually undo the many block rules in
1527 >. Or even easier, just create your own
1531 > file from scratch without the many ad
1532 blocking rules, and corresponding exceptions. Or lastly, if you are not
1533 concerned about the additional blocks that are done for privacy reasons, you
1534 can very easily over-ride <SPAN
1541 following very simple rule in your <TT
1555 > # Unblock everybody, everywhere
1557 HREF="../user-manual/actions-file.html#BLOCK"
1561 / # UN-Block *all* URLs</PRE
1568 Or even a more comprehensive reversing of various ad related actions:</P
1578 > # Unblock everybody, everywhere, and turn off appropriate filtering, etc
1580 HREF="../user-manual/actions-file.html#BLOCK"
1585 HREF="../user-manual/actions-file.html#FILTER-BANNERS-BY-SIZE"
1587 >-filter{banners-by-size}</A
1590 HREF="../user-manual/actions-file.html#FILTER-BANNERS-BY-LINK"
1592 >-filter{banners-by-link}</A
1599 / # UN-Block *all* URLs and allow ads</PRE
1608 > in this compound statement,
1613 HREF="../user-manual/actions-file.html#ALIASES"
1617 various pop-up blocking features.</P
1625 >3.29. How can I have custom template pages, like the
1641 > are specialized text files utilized by
1645 > for various purposes and can easily be modified using any text
1646 editor. All the template pages are installed in a sub-directory appropriately
1650 >. Knowing something about HTML syntax
1651 will of course be helpful.</P
1653 > Be forewarned that the default templates are subject to being overwritten
1654 during upgrades. You can, however, create completely new templates,
1655 place them in another directory and specify the alternate path in the main
1659 >. For details, have a look at the <A
1660 HREF="../user-manual/config.html#templdir"
1671 >3.30. How can I remove the <SPAN
1673 >"Go There Anyway"</SPAN
1684 > There is more than one way to do it (although Perl is not involved).</P
1686 > Editing the BLOCKED template page (see above) may dissuade some users, but
1687 this method is easily circumvented. Where you need this level of control, you
1688 might want to build <SPAN
1691 > from source, and disable various features that are
1692 available as compile-time options. You should
1696 > the sources as follows:</P
1706 > ./configure --disable-toggle --disable-editor --disable-force</PRE
1712 > This will create an executable with hard-coded security features so that
1716 > does not allow easy bypassing of blocked sites, or changing the
1717 current configuration via any connected user's web browser.</P
1719 > Finally, all of these features can also be toggled on/off via options in
1724 HREF="../user-manual/config.html#ACCESS-CONTROL"
1728 means you don't have to recompile anything.</P
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