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40 >Privoxy Frequently Asked Questions</TH
48 HREF="installation.html"
85 >3.1. What exactly is an <SPAN
94 > utilizes the concept of <SPAN
97 HREF="../user-manual/actions-file.html#ACTIONS"
102 that are used to manipulate and control web page data.
104 HREF="../user-manual/actions-file.html"
109 HREF="../user-manual/actions-file.html#ACTIONS"
116 > could take while processing a certain
117 request, are configured. Typically, you would define a set of default actions
118 that apply globally to all URLs, then add exceptions to these defaults where needed.
119 There is a wide array of actions available that give the user a high degree
120 of control and flexibility on how to process each and every web page.</P
122 > Actions can be defined on a <A
123 HREF="../user-manual/actions-file.html#AF-PATTERNS"
127 for single URLs, whole web sites, groups or parts thereof etc. Actions can also be
128 grouped together and then applied to requests matching one or more patterns.
129 There are many possible actions that might apply to any given site. As an example,
130 if you are blocking <A
131 HREF="http://en.wikipedia.org/wiki/Browser_cookie"
135 as one of your default actions, but need to accept cookies from a given site,
136 you would need to define an exception for this site in one of your actions
137 files, preferably in <TT
151 > concept confuses me. Please list
158 > For a comprehensive discussion of the actions concept, please refer
160 HREF="../user-manual/actions-file.html"
165 HREF="../user-manual/index.html"
170 HREF="../user-manual/actions-file.html#ACTIONS"
172 >list of all actions</A
175 HREF="../user-manual/actions-file.html#ACT-EXAMPLES"
179 > to get you started.</P
187 >3.3. How are actions files configured? What is the easiest
191 > Actions files are just text files in a special syntax and can be edited
192 with a text editor. But probably the easiest way is to access
196 >'s user interface with your web browser
198 HREF="http://config.privoxy.org/"
200 >http://config.privoxy.org/</A
210 HREF="http://config.privoxy.org/show-status"
213 change the current configuration</A
215 > from the menu. Note
216 that this feature must be explicitly enabled in the main config file
218 HREF="../user-manual/config.html#ENABLE-EDIT-ACTIONS"
220 >enable-edit-actions</A
229 >3.4. There are several different <SPAN
236 > Three actions files
237 are being included by the developers, to be used for
238 different purposes: These are
246 which is actively maintained by the <SPAN
250 developers and typically sets the default policies, <TT
253 >, where users are encouraged
254 to make their private customizations, and <TT
258 which is for internal <SPAN
263 HREF="../user-manual/actions-file.html"
265 >the actions chapter</A
268 HREF="../user-manual/index.html"
272 detailed explanation.</P
274 > Earlier versions included three different versions of the
278 > file. The new scheme allows for
279 greater flexibility of local configuration, and for browser based
280 selection of pre-defined <SPAN
282 >"aggressiveness"</SPAN
291 >3.5. Where can I get updated Actions Files?</A
294 > Based on your feedback and the continuing development, updates of
299 made available from time to time on the <A
300 HREF="http://sourceforge.net/project/showfiles.php?group_id=11118"
305 HREF="http://sf.net/projects/ijbswa/"
311 > If you wish to receive an email notification whenever we release updates of
315 > or the actions file, <A
316 HREF="http://lists.sourceforge.net/lists/listinfo/ijbswa-announce/"
319 to our announce mailing list</A
320 >, ijbswa-announce@lists.sourceforge.net.
329 >3.6. Can I use my old config files?</A
332 > The syntax and purpose of configuration files has remained roughly the
333 same throughout the 3.x series, but backwards compatibility is not guaranteed.
334 Also each release contains updated, <SPAN
338 therefore strongly recommended to install the newer configuration files
339 and merge back your modifications.
348 >3.7. Why is the configuration so complicated?</A
354 > is in the eye of the beholder. Those that are
355 familiar with some of the underlying concepts, such as regular expression
356 syntax, take to it like a fish takes to water. Also, software that tries
359 >"user friendly"</SPAN
360 >, often lacks sophistication and
361 flexibility. There is always that trade-off there between power vs.
362 easy-of-use. Furthermore, anyone is welcome to contribute ideas and
363 implementations to enhance <SPAN
375 >3.8. How can I make my Yahoo/Hotmail/Gmail account work?</A
378 > The default configuration shouldn't impact the usability of any of these services.
379 It may, however, make all <A
380 HREF="http://en.wikipedia.org/wiki/Browser_cookie"
384 temporary, so that your browser will forget your
385 login credentials in between browser sessions. If you would like not to have to log
386 in manually each time you access those websites, simply turn off all cookie handling
390 > file. An example for yahoo might
402 ># Allow all cookies for Yahoo login:
405 HREF="../user-manual/actions-file.html#CRUNCH-INCOMING-COOKIES"
407 >crunch-incoming-cookies</A
409 HREF="../user-manual/actions-file.html#CRUNCH-OUTGOING-COOKIES"
411 >crunch-outgoing-cookies</A
413 HREF="../user-manual/actions-file.html#SESSION-COOKIES-ONLY"
415 >session-cookies-only</A
417 .login.yahoo.com</PRE
424 > These kinds of sites are often quite complex and heavy with
426 HREF="http://en.wikipedia.org/wiki/Javascript"
441 HREF="../user-manual/actions-file.html#ALIASES"
456 ># Gmail is a _fragile_ site:
470 > Be sure to flush your browser's caches whenever making these kinds of
471 changes, just to make sure the changes <SPAN
477 > Make sure the domain, host and path are appropriate as well. Your browser can
478 tell you where you are specifically and you should use that information for
479 your configuration settings. Note that above it is not referenced as
483 >, which is a valid domain name.
492 >3.9. What's the difference between the
508 > is not entirely trivial. To
509 help you get started, we provide you with three different default action
513 > in the web based actions file editor at <A
514 HREF="http://config.privoxy.org/show-status"
516 >http://config.privoxy.org/show-status</A
519 HREF="../user-manual/actions-file.html"
526 > for a list of actions, and how the default
530 > Where the defaults are likely to break some sites, exceptions for
534 > sites are included, but in
535 general, the more aggressive your default settings are, the more exceptions
536 you will have to make later. New users are best to start off in
540 > setting. This is safest and will have the fewest
542 HREF="../user-manual/index.html"
549 for a more detailed discussion.</P
551 > It should be noted that the <SPAN
554 > profile (formerly known
557 >"Adventuresome"</SPAN
559 aggressive, and will make use of some of
563 > advanced features. Use at your own risk!</P
571 >3.10. Why can I change the configuration
572 with a browser? Does that not raise security issues?</A
575 > It may seem strange that regular users can edit the config files with their
576 browsers, although the whole <TT
580 belongs to the user <SPAN
583 >, with only 644 permissions.
586 > When you use the browser-based editor, <SPAN
590 itself is writing to the config files. Because
594 > is running as the user <SPAN
598 it can update its own config files.
604 > for multiple untrusted users (e.g. in
605 a LAN) or aren't entirely in control of your own browser, you will probably want
606 to make sure that the the web-based editor and remote toggle features are
615 HREF="../user-manual/config.html#ENABLE-EDIT-ACTIONS"
617 >enable-edit-actions</A
626 HREF="../user-manual/config.html#ENABLE-REMOTE-TOGGLE"
628 >enable-remote-toggle</A
633 HREF="../user-manual/config.html"
635 >main configuration file</A
642 > 3.0.7 these options are disabled by default.
651 >3.11. What is the <TT
654 > file? What is a <SPAN
661 HREF="../user-manual/filter-file.html"
674 > as supplied by the developers are defined.
675 Filters are a special subset of actions that can be used to modify or
676 remove web page content or headers on the fly. Content filters can
683 > in the page source,
684 header filters can be applied to either server or client headers.
685 Regular expressions are used to accomplish this.</P
687 > There are a number of pre-defined filters to deal with common annoyances. The
688 filters are only defined here, to invoke them, you need to use the
690 HREF="../user-manual/actions-file.html#FILTER"
697 > in one of the actions files. Content filtering is automatically
698 disabled for inappropriate MIME types, but if you now better than Privoxy
699 what should or should not be filtered you can filter any content you like.</P
708 > be confused with <A
709 HREF="../user-manual/actions-file.html#BLOCK"
716 is a completely different action, and is more typically used to block ads and
719 > If you are familiar with regular expressions, and HTML, you can look at
723 > with a text editor and define
724 your own filters. This is potentially a very powerful feature, but
725 requires some expertise in both regular expressions and HTML/HTTP.
727 place any modifications to the default filters, or any new ones you create
728 in a separate file, such as <TT
732 be overwritten during upgrades.
733 The ability to define multiple filter files
737 > is a new feature as of v. 3.0.5.</P
739 > There is no GUI editor option for this part of the configuration,
740 but you can disable/enable the various pre-defined filters of the included
745 HREF="http://config.privoxy.org/show-status"
747 >web-based actions file editor</A
749 Note that the custom actions editor must be explicitly enabled in
750 the main config file (see <A
751 HREF="../user-manual/config.html#ENABLE-EDIT-ACTIONS"
753 >enable-edit-actions</A
756 > If you intend to develop your own filters, you might want to have a look at
758 HREF="http://www.fabiankeil.de/sourcecode/pft/"
760 >Privoxy-Filter-Test</A
769 >3.12. How can I set up Privoxy to act as a proxy for my
776 > only responds to requests
780 > (localhost). To have it act as a server for
781 a network, this needs to be changed in the <A
782 HREF="../user-manual/config.html"
784 >main configuration file</A
789 HREF="../user-manual/config.html#LISTEN-ADDRESS"
794 option, which may be commented out with a <SPAN
798 it is uncommented, and assign it the address of the LAN gateway interface,
799 and port number to use. Assuming your LAN address is 192.168.1.1 and you
803 > on port 8118, this line
814 > listen-address 192.168.1.1:8118</PRE
820 > Save the file, and restart <SPAN
824 all browsers on the network then to use this address and port number.</P
826 > Alternately, you can have <SPAN
830 all available interfaces:</P
840 > listen-address :8118</PRE
851 HREF="../user-manual/config.html#PERMIT-ACCESS"
855 feature to limit connections. A firewall in this situation is recommended
858 > The above steps should be the same for any TCP network, regardless of
864 > on a LAN with untrusted users,
865 we recommend that you double-check the <A
866 HREF="../user-manual/config.html#ACCESS-CONTROL"
868 >access control and security</A
878 >3.13. Instead of ads, now I get a checkerboard pattern. I don't want to see anything.</A
881 > The replacement for blocked images can be controlled with the <A
882 HREF="../user-manual/actions-file.html#SET-IMAGE-BLOCKER"
886 >set-image-blocker</TT
889 >. You have the choice of a checkerboard pattern, a transparent 1x1 GIF
893 >), or a redirect to a custom image of your choice.
894 Note that this choice only has effect for images which are blocked as images, i.e.
895 whose URLs match both a <TT
898 HREF="../user-manual/actions-file.html#HANDLE-AS-IMAGE"
912 HREF="../user-manual/actions-file.html#BLOCK"
918 > If you want to see nothing, then change the <A
919 HREF="../user-manual/actions-file.html#SET-IMAGE-BLOCKER"
923 >set-image-blocker</TT
929 >. This can be done by editing the
933 > file, or through the <A
934 HREF="http://config.privoxy.org/show-status"
936 >web-based actions file editor</A
945 >3.14. Why would anybody want to see a checkerboard pattern?</A
949 HREF="general.html#WHATSANAD"
950 >telling which image is an ad and which
952 >, is an educated guess. While we hope that the standard configuration
953 is rather smart, it will make occasional mistakes. The checkerboard image is visually
954 decent, and it shows you where images have been blocked, which can be very
955 helpful in case some navigation aid or otherwise innocent image was
956 erroneously blocked. It is recommended for new users so they can
960 > what is happening. Some people might also enjoy seeing how
961 many banners they <SPAN
975 >3.15. I see some images being replaced with text
976 instead of the checkerboard image. Why and how do I get rid of this?</A
979 > This happens when the banners are not embedded in the HTML code of the
980 page itself, but in separate HTML (sub)documents that are loaded into (i)frames
981 or (i)layers, and these external HTML documents are blocked. Being non-images
982 they get replaced by a substitute HTML page rather than a substitute image,
983 which wouldn't work out technically, since the browser expects and accepts
984 only HTML when it has requested an HTML document. </P
986 > The substitute page adapts to the available space and shows itself as a
987 miniature two-liner if loaded into small frames, or full-blown with a
988 large red "BLOCKED" banner if space allows.</P
990 > If you prefer the banners to be blocked by images, you must see to it that
991 the HTML documents in which they are embedded are not blocked. Clicking
995 > link offered in the substitute page will show
996 you which rule blocked the page. After changing the rule and un-blocking
997 the HTML documents, the browser will try to load the actual banner images
998 and the usual image blocking will (hopefully!) kick in.</P
1006 >3.16. Can Privoxy run as a service
1010 > Yes. Version 3.0.5 introduces full <SPAN
1014 functionality. See <A
1015 HREF="../user-manual/installation.html#installation-pack-win"
1021 > for details on how to install and configure
1027 > Earlier 3.x versions could run as a system service using <B
1031 See the discussion at <A
1032 HREF="http://sourceforge.net/tracker/?func=detail&atid=361118&aid=485617&group_id=11118"
1034 >http://sourceforge.net/tracker/?func=detail&atid=361118&aid=485617&group_id=11118</A
1036 for details, and a sample configuration.</P
1044 >3.17. How can I make Privoxy work with other
1045 proxies like Squid or Tor?</A
1048 > This can be done and is often useful to combine the benefits of
1052 > with those of a another proxy.
1054 HREF="../user-manual/config.html#FORWARDING"
1056 >forwarding chapter</A
1059 HREF="../user-manual/index.html"
1063 describes how to do this, and the <A
1064 HREF="misc.html#TOR"
1065 > How do I use Privoxy together with
1075 >3.18. Can I just set Privoxy to use port 80
1076 and thus avoid individual browser configuration?</A
1079 > No, its more complicated than that. This only works with special kinds
1080 of proxies known as <SPAN
1082 >"intercepting"</SPAN
1083 > proxies (see below).</P
1091 >3.19. Can Privoxy run as a <SPAN
1093 >"transparent"</SPAN
1097 > The whole idea of Privoxy is to modify client requests
1098 and server responses in all sorts of ways and therefore
1099 it's not a transparent proxy as described in
1101 HREF="http://tools.ietf.org/html/rfc2616"
1106 > However, some people say <SPAN
1108 >"transparent proxy"</SPAN
1112 >"intercepting proxy"</SPAN
1113 >. If you are one of them,
1115 HREF="#intercepting"
1126 >3.20. Can Privoxy run as a <SPAN
1128 >"intercepting"</SPAN
1135 > can't intercept traffic itself,
1136 but it can handle requests that where intercepted and redirected
1137 with a packet filter (like <SPAN
1144 >), as long as the <TT
1154 > header is required by HTTP/1.1 and as most
1155 web sites rely on it anyway, this limitation shouldn't be a problem.</P
1157 > Please refer to your packet filter's documentation to learn how to
1158 intercept and redirect traffic into <SPAN
1162 Afterward you just have to configure <SPAN
1167 HREF="../user-manual/config.html#ACCEPT-INTERCEPTED-REQUESTS"
1170 intercepted requests</A
1179 >3.21. How can I configure Privoxy for use with Outlook
1185 >Outlook Express</SPAN
1188 >Internet Explorer</SPAN
1190 components to both render HTML, and fetch any HTTP requests that may be embedded in an HTML email.
1191 So however you have <SPAN
1194 > configured to work
1195 with IE, this configuration should automatically be shared.</P
1203 >3.22. How can I have separate rules just for HTML mail?</A
1206 > The short answer is, you can't. <SPAN
1210 of knowing which particular application makes a request, so there is no way to
1211 distinguish between web pages and HTML mail.
1215 > just blindly proxies all requests. In the
1218 >Outlook Express</SPAN
1219 > (see above), OE uses
1220 IE anyway, and there is no way for <SPAN
1224 be able to distinguish between them (nor could any other proxy type application for
1227 > For a good discussion of some of the issues involved (including privacy and
1228 security issues), see
1230 HREF="http://sourceforge.net/tracker/?func=detail&atid=211118&aid=629518&group_id=11118"
1232 >http://sourceforge.net/tracker/?func=detail&atid=211118&aid=629518&group_id=11118</A
1240 NAME="SNEAKY-COOKIES"
1241 >3.23. I sometimes notice cookies sneaking through. How?</A
1245 HREF="http://en.wikipedia.org/wiki/Browser_cookie"
1249 set in several ways. The classic method is via the
1253 > HTTP header. This is straightforward, and an
1254 easy one to manipulate, such as the <SPAN
1259 HREF="../user-manual/actions-file.html#SESSION-COOKIES-ONLY"
1261 >session-cookies-only</A
1263 There is also the possibility of using
1265 HREF="http://en.wikipedia.org/wiki/Javascript"
1274 >content-cookies</TT
1276 is trickier because the syntax can vary widely, and thus requires a certain
1277 amount of guesswork. It is not realistic to catch all of these short of
1278 disabling Javascript, which would break many sites. And lastly, if the
1279 cookies are embedded in a HTTPS/SSL secure session via Javascript, they are beyond
1288 > can help manage cookies in general, can help minimize
1289 the loss of privacy posed by cookies, but can't realistically stop all
1298 >3.24. Are all cookies bad? Why?</A
1301 > No, in fact there are many beneficial uses of
1303 HREF="http://en.wikipedia.org/wiki/Browser_cookie"
1306 >. Cookies are just a
1307 method that browsers can use to store data between pages, or between browser
1308 sessions. Sometimes there is a good reason for this, and the user's life is a
1309 bit easier as a result. But there is a long history of some websites taking
1310 advantage of this layer of trust, and using the data they glean from you and
1311 your browsing habits for their own purposes, and maybe to your potential
1312 detriment. Such sites are using you and storing their data on your system.
1313 That is why the privacy conscious watch from whom those cookies come, and why
1324 HREF="http://en.wikipedia.org/wiki/Browser_cookie"
1335 NAME="ALLOW-COOKIES"
1336 >3.25. How can I allow permanent cookies for my trusted sites?</A
1339 > There are several actions that relate to cookies. The default behavior is to
1342 >"session cookies"</SPAN
1343 >, which means the cookies only last
1344 for the current browser session. This eliminates most kinds of abuse related
1345 to cookies. But there may be cases where you want cookies to last.</P
1347 > To disable all cookie actions, so that cookies are allowed unrestricted,
1348 both in and out, for <TT
1361 > { -crunch-incoming-cookies -crunch-outgoing-cookies -session-cookies-only -filter{content-cookies} }
1368 > Place the above in <TT
1371 >. Note that some of these may
1372 be off by default anyway, so this might be redundant, but there is no harm
1373 being explicit in what you want to happen. <TT
1377 includes an alias for this situation, called
1380 >allow-all-cookies</TT
1389 >3.26. Can I have separate configurations for different users?</A
1392 > Each instance of <SPAN
1396 configuration, including such attributes as the TCP port that it listens on.
1397 What you can do is run multiple instances of <SPAN
1403 HREF="../user-manual/config.html#LISTEN-ADDRESS"
1407 configuration setting, and configuration path, and then
1408 each of these can have their own configurations. Think of it as per-port
1412 Simple enough for a few users, but for large installations, consider having
1413 groups of users that might share like configurations.</P
1421 >3.27. Can I set-up Privoxy as a whitelist of
1428 > Sure. There are a couple of things you can do for simple white-listing.
1429 Here's one real easy one:</P
1438 > ############################################################
1440 ############################################################
1442 HREF="../user-manual/actions-file.html#BLOCK"
1446 / # Block *all* URLs
1448 ############################################################
1450 ############################################################
1452 HREF="../user-manual/actions-file.html#BLOCK"
1458 games.example.com</PRE
1463 > This allows access to only those three sites by first blocking all URLs, and
1464 then subsequently allowing three specific exceptions.</P
1466 > Another approach is <SPAN
1473 > concept, which incorporates the notion of
1476 >"trusted referrers"</SPAN
1478 HREF="../user-manual/config.html#TRUSTFILE"
1480 >Trust documentation</A
1484 > These are fairly simple approaches and are not completely foolproof. There
1485 are various other configuration options that should be disabled (described
1486 elsewhere here and in <A
1487 HREF="../user-manual/"
1491 so that users can't modify their own configuration and easily circumvent the
1500 >3.28. How can I turn off ad-blocking?</A
1503 > Ad blocking is achieved through a complex application of various <SPAN
1508 HREF="../user-manual/actions-file.html"
1512 actions are deployed against simple images, banners, flash animations,
1513 text pages, JavaScript, pop-ups and pop-unders, etc., so its not as simple as
1514 just turning one or two actions off. The various actions that make up
1518 > ad blocking are hard-coded into the default configuration files. It
1519 has been assumed that everyone using <SPAN
1522 > is interested in this
1526 > If you want to do without this, there are several approaches you can take:
1527 You can manually undo the many block rules in
1531 >. Or even easier, just create your own
1535 > file from scratch without the many ad
1536 blocking rules, and corresponding exceptions. Or lastly, if you are not
1537 concerned about the additional blocks that are done for privacy reasons, you
1538 can very easily over-ride <SPAN
1545 following very simple rule in your <TT
1559 > # Unblock everybody, everywhere
1561 HREF="../user-manual/actions-file.html#BLOCK"
1565 / # UN-Block *all* URLs</PRE
1572 Or even a more comprehensive reversing of various ad related actions:</P
1582 > # Unblock everybody, everywhere, and turn off appropriate filtering, etc
1584 HREF="../user-manual/actions-file.html#BLOCK"
1589 HREF="../user-manual/actions-file.html#FILTER-BANNERS-BY-SIZE"
1591 >-filter{banners-by-size}</A
1594 HREF="../user-manual/actions-file.html#FILTER-BANNERS-BY-LINK"
1596 >-filter{banners-by-link}</A
1603 / # UN-Block *all* URLs and allow ads</PRE
1612 > in this compound statement,
1617 HREF="../user-manual/actions-file.html#ALIASES"
1621 various pop-up blocking features.</P
1629 >3.29. How can I have custom template pages, like the
1645 > are specialized text files utilized by
1649 > for various purposes and can easily be modified using any text
1650 editor. All the template pages are installed in a sub-directory appropriately
1654 >. Knowing something about HTML syntax
1655 will of course be helpful.</P
1657 > Be forewarned that the default templates are subject to being overwritten
1658 during upgrades. You can, however, create completely new templates,
1659 place them in another directory and specify the alternate path in the main
1663 >. For details, have a look at the <A
1664 HREF="../user-manual/config.html#templdir"
1675 >3.30. How can I remove the <SPAN
1677 >"Go There Anyway"</SPAN
1688 > There is more than one way to do it (although Perl is not involved).</P
1690 > Editing the BLOCKED template page (see above) may dissuade some users, but
1691 this method is easily circumvented. Where you need this level of control, you
1692 might want to build <SPAN
1695 > from source, and disable various features that are
1696 available as compile-time options. You should
1700 > the sources as follows:</P
1710 > ./configure --disable-toggle --disable-editor --disable-force</PRE
1716 > This will create an executable with hard-coded security features so that
1720 > does not allow easy bypassing of blocked sites, or changing the
1721 current configuration via any connected user's web browser.</P
1723 > Finally, all of these features can also be toggled on/off via options in
1728 HREF="../user-manual/config.html#ACCESS-CONTROL"
1732 means you don't have to recompile anything.</P
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