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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="http://sourceforge.net/project/showfiles.php?group_id=11118"
270 HREF="http://sf.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="http://lists.sourceforge.net/lists/listinfo/ijbswa-announce/"
284 to our announce mailing list</A
285 >, ijbswa-announce@lists.sourceforge.net.
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. Those that are
320 familiar with some of the underlying concepts, such as regular expression
321 syntax, take to it like a fish takes to water. Also, software that tries
324 >"user friendly"</SPAN
325 >, often lacks sophistication and
326 flexibility. There is always that trade-off there between power vs.
327 easy-of-use. Furthermore, anyone is welcome to contribute ideas and
328 implementations to enhance <SPAN
340 >3.8. How can I make my Yahoo/Hotmail/Gmail account work?</A
343 > The default configuration shouldn't impact the usability of any of these services.
344 It may, however, make all <A
345 HREF="http://en.wikipedia.org/wiki/Browser_cookie"
349 temporary, so that your browser will forget your
350 login credentials in between browser sessions. If you would like not to have to log
351 in manually each time you access those websites, simply turn off all cookie handling
355 > file. An example for yahoo might
367 ># Allow all cookies for Yahoo login:
370 HREF="../user-manual/actions-file.html#CRUNCH-INCOMING-COOKIES"
372 >crunch-incoming-cookies</A
374 HREF="../user-manual/actions-file.html#CRUNCH-OUTGOING-COOKIES"
376 >crunch-outgoing-cookies</A
378 HREF="../user-manual/actions-file.html#SESSION-COOKIES-ONLY"
380 >session-cookies-only</A
382 .login.yahoo.com</PRE
389 > These kinds of sites are often quite complex and heavy with
391 HREF="http://en.wikipedia.org/wiki/Javascript"
406 HREF="../user-manual/actions-file.html#ALIASES"
421 ># Gmail is a _fragile_ site:
435 > Be sure to flush your browser's caches whenever making these kinds of
436 changes, just to make sure the changes <SPAN
442 > Make sure the domain, host and path are appropriate as well. Your browser can
443 tell you where you are specifically and you should use that information for
444 your configuration settings. Note that above it is not referenced as
448 >, which is a valid domain name.
457 >3.9. What's the difference between the
473 > is not entirely trivial. To
474 help you get started, we provide you with three different default action
478 > in the web based actions file editor at <A
479 HREF="http://config.privoxy.org/show-status"
481 >http://config.privoxy.org/show-status</A
484 HREF="../user-manual/actions-file.html"
491 > for a list of actions, and how the default
495 > Where the defaults are likely to break some sites, exceptions for
499 > sites are included, but in
500 general, the more aggressive your default settings are, the more exceptions
501 you will have to make later. New users are best to start off in
505 > setting. This is safest and will have the fewest
507 HREF="../user-manual/index.html"
514 for a more detailed discussion.</P
516 > It should be noted that the <SPAN
519 > profile (formerly known
522 >"Adventuresome"</SPAN
524 aggressive, and will make use of some of
528 > advanced features. Use at your own risk!</P
536 >3.10. Why can I change the configuration
537 with a browser? Does that not raise security issues?</A
540 > It may seem strange that regular users can edit the config files with their
541 browsers, although the whole <TT
545 belongs to the user <SPAN
548 >, with only 644 permissions.
551 > When you use the browser-based editor, <SPAN
555 itself is writing to the config files. Because
559 > is running as the user <SPAN
563 it can update its own config files.
569 > for multiple untrusted users (e.g. in
570 a LAN) or aren't entirely in control of your own browser, you will probably want
571 to make sure that the the web-based editor and remote toggle features are
580 HREF="../user-manual/config.html#ENABLE-EDIT-ACTIONS"
582 >enable-edit-actions</A
591 HREF="../user-manual/config.html#ENABLE-REMOTE-TOGGLE"
593 >enable-remote-toggle</A
598 HREF="../user-manual/config.html"
600 >main configuration file</A
607 > 3.0.7 these options are disabled by default.
616 >3.11. What is the <TT
619 > file? What is a <SPAN
626 HREF="../user-manual/filter-file.html"
639 > as supplied by the developers are defined.
640 Filters are a special subset of actions that can be used to modify or
641 remove web page content or headers on the fly. Content filters can
648 > in the page source,
649 header filters can be applied to either server or client headers.
650 Regular expressions are used to accomplish this.</P
652 > There are a number of pre-defined filters to deal with common annoyances. The
653 filters are only defined here, to invoke them, you need to use the
655 HREF="../user-manual/actions-file.html#FILTER"
662 > in one of the actions files. Content filtering is automatically
663 disabled for inappropriate MIME types, but if you now better than Privoxy
664 what should or should not be filtered you can filter any content you like.</P
673 > be confused with <A
674 HREF="../user-manual/actions-file.html#BLOCK"
681 is a completely different action, and is more typically used to block ads and
684 > If you are familiar with regular expressions, and HTML, you can look at
688 > with a text editor and define
689 your own filters. This is potentially a very powerful feature, but
690 requires some expertise in both regular expressions and HTML/HTTP.
692 place any modifications to the default filters, or any new ones you create
693 in a separate file, such as <TT
697 be overwritten during upgrades.
698 The ability to define multiple filter files
702 > is a new feature as of v. 3.0.5.</P
704 > There is no GUI editor option for this part of the configuration,
705 but you can disable/enable the various pre-defined filters of the included
710 HREF="http://config.privoxy.org/show-status"
712 >web-based actions file editor</A
714 Note that the custom actions editor must be explicitly enabled in
715 the main config file (see <A
716 HREF="../user-manual/config.html#ENABLE-EDIT-ACTIONS"
718 >enable-edit-actions</A
721 > If you intend to develop your own filters, you might want to have a look at
723 HREF="http://www.fabiankeil.de/sourcecode/pft/"
725 >Privoxy-Filter-Test</A
734 >3.12. How can I set up Privoxy to act as a proxy for my
741 > only responds to requests
745 > (localhost). To have it act as a server for
746 a network, this needs to be changed in the <A
747 HREF="../user-manual/config.html"
749 >main configuration file</A
754 HREF="../user-manual/config.html#LISTEN-ADDRESS"
759 option, which may be commented out with a <SPAN
763 it is uncommented, and assign it the address of the LAN gateway interface,
764 and port number to use. Assuming your LAN address is 192.168.1.1 and you
768 > on port 8118, this line
779 > listen-address 192.168.1.1:8118</PRE
785 > Save the file, and restart <SPAN
789 all browsers on the network then to use this address and port number.</P
791 > Alternately, you can have <SPAN
795 all available interfaces:</P
805 > listen-address :8118</PRE
816 HREF="../user-manual/config.html#PERMIT-ACCESS"
820 feature to limit connections. A firewall in this situation is recommended
823 > The above steps should be the same for any TCP network, regardless of
829 > on a LAN with untrusted users,
830 we recommend that you double-check the <A
831 HREF="../user-manual/config.html#ACCESS-CONTROL"
833 >access control and security</A
843 >3.13. Instead of ads, now I get a checkerboard pattern. I don't want to see anything.</A
846 > The replacement for blocked images can be controlled with the <A
847 HREF="../user-manual/actions-file.html#SET-IMAGE-BLOCKER"
851 >set-image-blocker</TT
854 >. You have the choice of a checkerboard pattern, a transparent 1x1 GIF
858 >), or a redirect to a custom image of your choice.
859 Note that this choice only has effect for images which are blocked as images, i.e.
860 whose URLs match both a <TT
863 HREF="../user-manual/actions-file.html#HANDLE-AS-IMAGE"
877 HREF="../user-manual/actions-file.html#BLOCK"
883 > If you want to see nothing, then change the <A
884 HREF="../user-manual/actions-file.html#SET-IMAGE-BLOCKER"
888 >set-image-blocker</TT
894 >. This can be done by editing the
898 > file, or through the <A
899 HREF="http://config.privoxy.org/show-status"
901 >web-based actions file editor</A
910 >3.14. Why would anybody want to see a checkerboard pattern?</A
914 HREF="general.html#WHATSANAD"
915 >telling which image is an ad and which
917 >, is an educated guess. While we hope that the standard configuration
918 is rather smart, it will make occasional mistakes. The checkerboard image is visually
919 decent, and it shows you where images have been blocked, which can be very
920 helpful in case some navigation aid or otherwise innocent image was
921 erroneously blocked. It is recommended for new users so they can
925 > what is happening. Some people might also enjoy seeing how
926 many banners they <SPAN
940 >3.15. I see some images being replaced with text
941 instead of the checkerboard image. Why and how do I get rid of this?</A
944 > This happens when the banners are not embedded in the HTML code of the
945 page itself, but in separate HTML (sub)documents that are loaded into (i)frames
946 or (i)layers, and these external HTML documents are blocked. Being non-images
947 they get replaced by a substitute HTML page rather than a substitute image,
948 which wouldn't work out technically, since the browser expects and accepts
949 only HTML when it has requested an HTML document. </P
951 > The substitute page adapts to the available space and shows itself as a
952 miniature two-liner if loaded into small frames, or full-blown with a
953 large red "BLOCKED" banner if space allows.</P
955 > If you prefer the banners to be blocked by images, you must see to it that
956 the HTML documents in which they are embedded are not blocked. Clicking
960 > link offered in the substitute page will show
961 you which rule blocked the page. After changing the rule and un-blocking
962 the HTML documents, the browser will try to load the actual banner images
963 and the usual image blocking will (hopefully!) kick in.</P
971 >3.16. Can Privoxy run as a service
975 > Yes. Version 3.0.5 introduces full <SPAN
979 functionality. See <A
980 HREF="../user-manual/installation.html#installation-pack-win"
986 > for details on how to install and configure
992 > Earlier 3.x versions could run as a system service using <B
996 See the discussion at <A
997 HREF="http://sourceforge.net/tracker/?func=detail&atid=361118&aid=485617&group_id=11118"
999 >http://sourceforge.net/tracker/?func=detail&atid=361118&aid=485617&group_id=11118</A
1001 for details, and a sample configuration.</P
1009 >3.17. How can I make Privoxy work with other
1010 proxies like Squid or Tor?</A
1013 > This can be done and is often useful to combine the benefits of
1017 > with those of a another proxy.
1019 HREF="../user-manual/config.html#FORWARDING"
1021 >forwarding chapter</A
1024 HREF="../user-manual/index.html"
1028 describes how to do this, and the <A
1029 HREF="misc.html#TOR"
1030 > How do I use Privoxy together with
1040 >3.18. Can I just set Privoxy to use port 80
1041 and thus avoid individual browser configuration?</A
1044 > No, its more complicated than that. This only works with special kinds
1045 of proxies known as <SPAN
1047 >"intercepting"</SPAN
1048 > proxies (see below).</P
1056 >3.19. Can Privoxy run as a <SPAN
1058 >"transparent"</SPAN
1062 > The whole idea of Privoxy is to modify client requests
1063 and server responses in all sorts of ways and therefore
1064 it's not a transparent proxy as described in
1066 HREF="http://tools.ietf.org/html/rfc2616"
1071 > However, some people say <SPAN
1073 >"transparent proxy"</SPAN
1077 >"intercepting proxy"</SPAN
1078 >. If you are one of them,
1080 HREF="#intercepting"
1091 >3.20. Can Privoxy run as a <SPAN
1093 >"intercepting"</SPAN
1100 > can't intercept traffic itself,
1101 but it can handle requests that where intercepted and redirected
1102 with a packet filter (like <SPAN
1109 >), as long as the <TT
1119 > header is required by HTTP/1.1 and as most
1120 web sites rely on it anyway, this limitation shouldn't be a problem.</P
1122 > Please refer to your packet filter's documentation to learn how to
1123 intercept and redirect traffic into <SPAN
1127 Afterward you just have to configure <SPAN
1132 HREF="../user-manual/config.html#ACCEPT-INTERCEPTED-REQUESTS"
1135 intercepted requests</A
1144 >3.21. How can I configure Privoxy for use with Outlook?</A
1150 > prior to Office 2007, use
1153 >Internet Explorer</SPAN
1154 > components to both render HTML,
1155 and fetch any HTTP requests that may be embedded in an HTML email. So however
1159 > configured to work with IE, this
1160 configuration should automatically be shared, at least with older version of
1161 Internet Explorer.</P
1163 > Starting with Office 2007, Microsoft is instead using the MS-Word rendering
1164 engine with Outlook. It is unknown whether this can be configured to use a
1174 >3.22. How can I have separate rules just for HTML mail?</A
1177 > The short answer is, you can't. <SPAN
1181 of knowing which particular application makes a request, so there is no way to
1182 distinguish between web pages and HTML mail.
1186 > just blindly proxies all requests. In the
1189 >Outlook Express</SPAN
1190 > (see above), OE uses
1191 IE anyway, and there is no way for <SPAN
1195 be able to distinguish between them (nor could any other proxy type application for
1198 > For a good discussion of some of the issues involved (including privacy and
1199 security issues), see
1201 HREF="http://sourceforge.net/tracker/?func=detail&atid=211118&aid=629518&group_id=11118"
1203 >http://sourceforge.net/tracker/?func=detail&atid=211118&aid=629518&group_id=11118</A
1211 NAME="SNEAKY-COOKIES"
1212 >3.23. I sometimes notice cookies sneaking through. How?</A
1216 HREF="http://en.wikipedia.org/wiki/Browser_cookie"
1220 set in several ways. The classic method is via the
1224 > HTTP header. This is straightforward, and an
1225 easy one to manipulate, such as the <SPAN
1230 HREF="../user-manual/actions-file.html#SESSION-COOKIES-ONLY"
1232 >session-cookies-only</A
1234 There is also the possibility of using
1236 HREF="http://en.wikipedia.org/wiki/Javascript"
1245 >content-cookies</TT
1247 is trickier because the syntax can vary widely, and thus requires a certain
1248 amount of guesswork. It is not realistic to catch all of these short of
1249 disabling Javascript, which would break many sites. And lastly, if the
1250 cookies are embedded in a HTTPS/SSL secure session via Javascript, they are beyond
1259 > can help manage cookies in general, can help minimize
1260 the loss of privacy posed by cookies, but can't realistically stop all
1269 >3.24. Are all cookies bad? Why?</A
1272 > No, in fact there are many beneficial uses of
1274 HREF="http://en.wikipedia.org/wiki/Browser_cookie"
1277 >. Cookies are just a
1278 method that browsers can use to store data between pages, or between browser
1279 sessions. Sometimes there is a good reason for this, and the user's life is a
1280 bit easier as a result. But there is a long history of some websites taking
1281 advantage of this layer of trust, and using the data they glean from you and
1282 your browsing habits for their own purposes, and maybe to your potential
1283 detriment. Such sites are using you and storing their data on your system.
1284 That is why the privacy conscious watch from whom those cookies come, and why
1295 HREF="http://en.wikipedia.org/wiki/Browser_cookie"
1306 NAME="ALLOW-COOKIES"
1307 >3.25. How can I allow permanent cookies for my trusted sites?</A
1310 > There are several actions that relate to cookies. The default behavior is to
1313 >"session cookies"</SPAN
1314 >, which means the cookies only last
1315 for the current browser session. This eliminates most kinds of abuse related
1316 to cookies. But there may be cases where you want cookies to last.</P
1318 > To disable all cookie actions, so that cookies are allowed unrestricted,
1319 both in and out, for <TT
1332 > { -crunch-incoming-cookies -crunch-outgoing-cookies -session-cookies-only -filter{content-cookies} }
1339 > Place the above in <TT
1342 >. Note that some of these may
1343 be off by default anyway, so this might be redundant, but there is no harm
1344 being explicit in what you want to happen. <TT
1348 includes an alias for this situation, called
1351 >allow-all-cookies</TT
1360 >3.26. Can I have separate configurations for different users?</A
1363 > Each instance of <SPAN
1367 configuration, including such attributes as the TCP port that it listens on.
1368 What you can do is run multiple instances of <SPAN
1374 HREF="../user-manual/config.html#LISTEN-ADDRESS"
1378 configuration setting, and configuration path, and then
1379 each of these can have their own configurations. Think of it as per-port
1383 Simple enough for a few users, but for large installations, consider having
1384 groups of users that might share like configurations.</P
1392 >3.27. Can I set-up Privoxy as a whitelist of
1399 > Sure. There are a couple of things you can do for simple white-listing.
1400 Here's one real easy one:</P
1409 > ############################################################
1411 ############################################################
1413 HREF="../user-manual/actions-file.html#BLOCK"
1417 / # Block *all* URLs
1419 ############################################################
1421 ############################################################
1423 HREF="../user-manual/actions-file.html#BLOCK"
1429 games.example.com</PRE
1434 > This allows access to only those three sites by first blocking all URLs, and
1435 then subsequently allowing three specific exceptions.</P
1437 > Another approach is <SPAN
1444 > concept, which incorporates the notion of
1447 >"trusted referrers"</SPAN
1449 HREF="../user-manual/config.html#TRUSTFILE"
1451 >Trust documentation</A
1455 > These are fairly simple approaches and are not completely foolproof. There
1456 are various other configuration options that should be disabled (described
1457 elsewhere here and in <A
1458 HREF="../user-manual/"
1462 so that users can't modify their own configuration and easily circumvent the
1471 >3.28. How can I turn off ad-blocking?</A
1474 > Ad blocking is achieved through a complex application of various <SPAN
1479 HREF="../user-manual/actions-file.html"
1483 actions are deployed against simple images, banners, flash animations,
1484 text pages, JavaScript, pop-ups and pop-unders, etc., so its not as simple as
1485 just turning one or two actions off. The various actions that make up
1489 > ad blocking are hard-coded into the default configuration files. It
1490 has been assumed that everyone using <SPAN
1493 > is interested in this
1497 > If you want to do without this, there are several approaches you can take:
1498 You can manually undo the many block rules in
1502 >. Or even easier, just create your own
1506 > file from scratch without the many ad
1507 blocking rules, and corresponding exceptions. Or lastly, if you are not
1508 concerned about the additional blocks that are done for privacy reasons, you
1509 can very easily over-ride <SPAN
1516 following very simple rule in your <TT
1530 > # Unblock everybody, everywhere
1532 HREF="../user-manual/actions-file.html#BLOCK"
1536 / # UN-Block *all* URLs</PRE
1543 Or even a more comprehensive reversing of various ad related actions:</P
1553 > # Unblock everybody, everywhere, and turn off appropriate filtering, etc
1555 HREF="../user-manual/actions-file.html#BLOCK"
1560 HREF="../user-manual/actions-file.html#FILTER-BANNERS-BY-SIZE"
1562 >-filter{banners-by-size}</A
1565 HREF="../user-manual/actions-file.html#FILTER-BANNERS-BY-LINK"
1567 >-filter{banners-by-link}</A
1574 / # UN-Block *all* URLs and allow ads</PRE
1583 > in this compound statement,
1588 HREF="../user-manual/actions-file.html#ALIASES"
1592 various pop-up blocking features.</P
1600 >3.29. How can I have custom template pages, like the
1616 > are specialized text files utilized by
1620 > for various purposes and can easily be modified using any text
1621 editor. All the template pages are installed in a sub-directory appropriately
1625 >. Knowing something about HTML syntax
1626 will of course be helpful.</P
1628 > Be forewarned that the default templates are subject to being overwritten
1629 during upgrades. You can, however, create completely new templates,
1630 place them in another directory and specify the alternate path in the main
1634 >. For details, have a look at the <A
1635 HREF="../user-manual/config.html#templdir"
1646 >3.30. How can I remove the <SPAN
1648 >"Go There Anyway"</SPAN
1659 > There is more than one way to do it (although Perl is not involved).</P
1661 > Editing the BLOCKED template page (see above) may dissuade some users, but
1662 this method is easily circumvented. Where you need this level of control, you
1663 might want to build <SPAN
1666 > from source, and disable various features that are
1667 available as compile-time options. You should
1671 > the sources as follows:</P
1681 > ./configure --disable-toggle --disable-editor --disable-force</PRE
1687 > This will create an executable with hard-coded security features so that
1691 > does not allow easy bypassing of blocked sites, or changing the
1692 current configuration via any connected user's web browser.</P
1694 > Finally, all of these features can also be toggled on/off via options in
1699 HREF="../user-manual/config.html#ACCESS-CONTROL"
1703 means you don't have to recompile anything.</P
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