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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
256 >, where users are encouraged
257 to make their private customizations, and <TT
261 which is for internal <SPAN
266 HREF="../user-manual/actions-file.html"
268 >the actions chapter</A
271 HREF="../user-manual/index.html"
275 detailed explanation.</P
277 > Earlier versions included three different versions of the
281 > file. The new scheme allows for
282 greater flexibility of local configuration, and for browser based
283 selection of pre-defined <SPAN
285 >"aggressiveness"</SPAN
294 >3.5. Where can I get updated Actions Files?</A
297 > Based on your feedback and the continuing development, updates of
302 made available from time to time on the <A
303 HREF="http://sourceforge.net/project/showfiles.php?group_id=11118"
308 HREF="http://sf.net/projects/ijbswa/"
314 > If you wish to receive an email notification whenever we release updates of
318 > or the actions file, <A
319 HREF="http://lists.sourceforge.net/lists/listinfo/ijbswa-announce/"
322 to our announce mailing list</A
323 >, ijbswa-announce@lists.sourceforge.net.
332 >3.6. Can I use my old config files?</A
335 > The syntax and purpose of configuration files has remained roughly the
336 same throughout the 3.x series, but backwards compatibility is not guaranteed.
337 Also each release contains updated, <SPAN
341 therefore strongly recommended to install the newer configuration files
342 and merge back your modifications.
351 >3.7. Why is the configuration so complicated?</A
357 > is in the eye of the beholder. Those that are
358 familiar with some of the underlying concepts, such as regular expression
359 syntax, take to it like a fish takes to water. Also, software that tries
362 >"user friendly"</SPAN
363 >, often lacks sophistication and
364 flexibility. There is always that trade-off there between power vs.
365 easy-of-use. Furthermore, anyone is welcome to contribute ideas and
366 implementations to enhance <SPAN
378 >3.8. How can I make my Yahoo/Hotmail/Gmail account work?</A
381 > The default configuration shouldn't impact the usability of any of these services.
382 It may, however, make all <A
383 HREF="http://en.wikipedia.org/wiki/Browser_cookie"
387 temporary, so that your browser will forget your
388 login credentials in between browser sessions. If you would like not to have to log
389 in manually each time you access those websites, simply turn off all cookie handling
393 > file. An example for yahoo might
405 ># Allow all cookies for Yahoo login:
408 HREF="../user-manual/actions-file.html#CRUNCH-INCOMING-COOKIES"
410 >crunch-incoming-cookies</A
412 HREF="../user-manual/actions-file.html#CRUNCH-OUTGOING-COOKIES"
414 >crunch-outgoing-cookies</A
416 HREF="../user-manual/actions-file.html#SESSION-COOKIES-ONLY"
418 >session-cookies-only</A
420 .login.yahoo.com</PRE
427 > These kinds of sites are often quite complex and heavy with
429 HREF="http://en.wikipedia.org/wiki/Javascript"
444 HREF="../user-manual/actions-file.html#ALIASES"
459 ># Gmail is a _fragile_ site:
473 > Be sure to flush your browser's caches whenever making these kinds of
474 changes, just to make sure the changes <SPAN
480 > Make sure the domain, host and path are appropriate as well. Your browser can
481 tell you where you are specifically and you should use that information for
482 your configuration settings. Note that above it is not referenced as
486 >, which is a valid domain name.
495 >3.9. What's the difference between the
511 > is not entirely trivial. To
512 help you get started, we provide you with three different default action
516 > in the web based actions file editor at <A
517 HREF="http://config.privoxy.org/show-status"
519 >http://config.privoxy.org/show-status</A
522 HREF="../user-manual/actions-file.html"
529 > for a list of actions, and how the default
533 > Where the defaults are likely to break some sites, exceptions for
537 > sites are included, but in
538 general, the more aggressive your default settings are, the more exceptions
539 you will have to make later. New users are best to start off in
543 > setting. This is safest and will have the fewest
545 HREF="../user-manual/index.html"
552 for a more detailed discussion.</P
554 > It should be noted that the <SPAN
557 > profile (formerly known
560 >"Adventuresome"</SPAN
562 aggressive, and will make use of some of
566 > advanced features. Use at your own risk!</P
574 >3.10. Why can I change the configuration
575 with a browser? Does that not raise security issues?</A
578 > It may seem strange that regular users can edit the config files with their
579 browsers, although the whole <TT
583 belongs to the user <SPAN
586 >, with only 644 permissions.
589 > When you use the browser-based editor, <SPAN
593 itself is writing to the config files. Because
597 > is running as the user <SPAN
601 it can update its own config files.
607 > for multiple untrusted users (e.g. in
608 a LAN) or aren't entirely in control of your own browser, you will probably want
609 to make sure that the the web-based editor and remote toggle features are
618 HREF="../user-manual/config.html#ENABLE-EDIT-ACTIONS"
620 >enable-edit-actions</A
629 HREF="../user-manual/config.html#ENABLE-REMOTE-TOGGLE"
631 >enable-remote-toggle</A
636 HREF="../user-manual/config.html"
638 >main configuration file</A
645 > 3.0.7 these options are disabled by default.
654 >3.11. What is the <TT
657 > file? What is a <SPAN
664 HREF="../user-manual/filter-file.html"
677 > as supplied by the developers are defined.
678 Filters are a special subset of actions that can be used to modify or
679 remove web page content or headers on the fly. Content filters can
686 > in the page source,
687 header filters can be applied to either server or client headers.
688 Regular expressions are used to accomplish this.</P
690 > There are a number of pre-defined filters to deal with common annoyances. The
691 filters are only defined here, to invoke them, you need to use the
693 HREF="../user-manual/actions-file.html#FILTER"
700 > in one of the actions files. Content filtering is automatically
701 disabled for inappropriate MIME types, but if you now better than Privoxy
702 what should or should not be filtered you can filter any content you like.</P
711 > be confused with <A
712 HREF="../user-manual/actions-file.html#BLOCK"
719 is a completely different action, and is more typically used to block ads and
722 > If you are familiar with regular expressions, and HTML, you can look at
726 > with a text editor and define
727 your own filters. This is potentially a very powerful feature, but
728 requires some expertise in both regular expressions and HTML/HTTP.
730 place any modifications to the default filters, or any new ones you create
731 in a separate file, such as <TT
735 be overwritten during upgrades.
736 The ability to define multiple filter files
740 > is a new feature as of v. 3.0.5.</P
742 > There is no GUI editor option for this part of the configuration,
743 but you can disable/enable the various pre-defined filters of the included
748 HREF="http://config.privoxy.org/show-status"
750 >web-based actions file editor</A
752 Note that the custom actions editor must be explicitly enabled in
753 the main config file (see <A
754 HREF="../user-manual/config.html#ENABLE-EDIT-ACTIONS"
756 >enable-edit-actions</A
759 > If you intend to develop your own filters, you might want to have a look at
761 HREF="http://www.fabiankeil.de/sourcecode/pft/"
763 >Privoxy-Filter-Test</A
772 >3.12. How can I set up Privoxy to act as a proxy for my
779 > only responds to requests
783 > (localhost). To have it act as a server for
784 a network, this needs to be changed in the <A
785 HREF="../user-manual/config.html"
787 >main configuration file</A
792 HREF="../user-manual/config.html#LISTEN-ADDRESS"
797 option, which may be commented out with a <SPAN
801 it is uncommented, and assign it the address of the LAN gateway interface,
802 and port number to use. Assuming your LAN address is 192.168.1.1 and you
806 > on port 8118, this line
817 > listen-address 192.168.1.1:8118</PRE
823 > Save the file, and restart <SPAN
827 all browsers on the network then to use this address and port number.</P
829 > Alternately, you can have <SPAN
833 all available interfaces:</P
843 > listen-address :8118</PRE
854 HREF="../user-manual/config.html#PERMIT-ACCESS"
858 feature to limit connections. A firewall in this situation is recommended
861 > The above steps should be the same for any TCP network, regardless of
867 > on a LAN with untrusted users,
868 we recommend that you double-check the <A
869 HREF="../user-manual/config.html#ACCESS-CONTROL"
871 >access control and security</A
881 >3.13. Instead of ads, now I get a checkerboard pattern. I don't want to see anything.</A
884 > The replacement for blocked images can be controlled with the <A
885 HREF="../user-manual/actions-file.html#SET-IMAGE-BLOCKER"
889 >set-image-blocker</TT
892 >. You have the choice of a checkerboard pattern, a transparent 1x1 GIF
896 >), or a redirect to a custom image of your choice.
897 Note that this choice only has effect for images which are blocked as images, i.e.
898 whose URLs match both a <TT
901 HREF="../user-manual/actions-file.html#HANDLE-AS-IMAGE"
915 HREF="../user-manual/actions-file.html#BLOCK"
921 > If you want to see nothing, then change the <A
922 HREF="../user-manual/actions-file.html#SET-IMAGE-BLOCKER"
926 >set-image-blocker</TT
932 >. This can be done by editing the
936 > file, or through the <A
937 HREF="http://config.privoxy.org/show-status"
939 >web-based actions file editor</A
948 >3.14. Why would anybody want to see a checkerboard pattern?</A
952 HREF="general.html#WHATSANAD"
953 >telling which image is an ad and which
955 >, is an educated guess. While we hope that the standard configuration
956 is rather smart, it will make occasional mistakes. The checkerboard image is visually
957 decent, and it shows you where images have been blocked, which can be very
958 helpful in case some navigation aid or otherwise innocent image was
959 erroneously blocked. It is recommended for new users so they can
963 > what is happening. Some people might also enjoy seeing how
964 many banners they <SPAN
978 >3.15. I see some images being replaced with text
979 instead of the checkerboard image. Why and how do I get rid of this?</A
982 > This happens when the banners are not embedded in the HTML code of the
983 page itself, but in separate HTML (sub)documents that are loaded into (i)frames
984 or (i)layers, and these external HTML documents are blocked. Being non-images
985 they get replaced by a substitute HTML page rather than a substitute image,
986 which wouldn't work out technically, since the browser expects and accepts
987 only HTML when it has requested an HTML document. </P
989 > The substitute page adapts to the available space and shows itself as a
990 miniature two-liner if loaded into small frames, or full-blown with a
991 large red "BLOCKED" banner if space allows.</P
993 > If you prefer the banners to be blocked by images, you must see to it that
994 the HTML documents in which they are embedded are not blocked. Clicking
998 > link offered in the substitute page will show
999 you which rule blocked the page. After changing the rule and un-blocking
1000 the HTML documents, the browser will try to load the actual banner images
1001 and the usual image blocking will (hopefully!) kick in.</P
1009 >3.16. Can Privoxy run as a service
1013 > Yes. Version 3.0.5 introduces full <SPAN
1017 functionality. See <A
1018 HREF="../user-manual/installation.html#installation-pack-win"
1024 > for details on how to install and configure
1030 > Earlier 3.x versions could run as a system service using <B
1034 See the discussion at <A
1035 HREF="http://sourceforge.net/tracker/?func=detail&atid=361118&aid=485617&group_id=11118"
1037 >http://sourceforge.net/tracker/?func=detail&atid=361118&aid=485617&group_id=11118</A
1039 for details, and a sample configuration.</P
1047 >3.17. How can I make Privoxy work with other
1048 proxies like Squid or Tor?</A
1051 > This can be done and is often useful to combine the benefits of
1055 > with those of a another proxy.
1057 HREF="../user-manual/config.html#FORWARDING"
1059 >forwarding chapter</A
1062 HREF="../user-manual/index.html"
1066 describes how to do this, and the <A
1067 HREF="misc.html#TOR"
1068 > How do I use Privoxy together with
1078 >3.18. Can I just set Privoxy to use port 80
1079 and thus avoid individual browser configuration?</A
1082 > No, its more complicated than that. This only works with special kinds
1083 of proxies known as <SPAN
1085 >"intercepting"</SPAN
1086 > proxies (see below).</P
1094 >3.19. Can Privoxy run as a <SPAN
1096 >"transparent"</SPAN
1100 > The whole idea of Privoxy is to modify client requests
1101 and server responses in all sorts of ways and therefore
1102 it's not a transparent proxy as described in
1104 HREF="http://tools.ietf.org/html/rfc2616"
1109 > However, some people say <SPAN
1111 >"transparent proxy"</SPAN
1115 >"intercepting proxy"</SPAN
1116 >. If you are one of them,
1118 HREF="#intercepting"
1129 >3.20. Can Privoxy run as a <SPAN
1131 >"intercepting"</SPAN
1138 > can't intercept traffic itself,
1139 but it can handle requests that where intercepted and redirected
1140 with a packet filter (like <SPAN
1147 >), as long as the <TT
1157 > header is required by HTTP/1.1 and as most
1158 web sites rely on it anyway, this limitation shouldn't be a problem.</P
1160 > Please refer to your packet filter's documentation to learn how to
1161 intercept and redirect traffic into <SPAN
1165 Afterward you just have to configure <SPAN
1170 HREF="../user-manual/config.html#ACCEPT-INTERCEPTED-REQUESTS"
1173 intercepted requests</A
1182 >3.21. How can I configure Privoxy for use with Outlook
1188 >Outlook Express</SPAN
1191 >Internet Explorer</SPAN
1193 components to both render HTML, and fetch any HTTP requests that may be embedded in an HTML email.
1194 So however you have <SPAN
1197 > configured to work
1198 with IE, this configuration should automatically be shared.</P
1206 >3.22. How can I have separate rules just for HTML mail?</A
1209 > The short answer is, you can't. <SPAN
1213 of knowing which particular application makes a request, so there is no way to
1214 distinguish between web pages and HTML mail.
1218 > just blindly proxies all requests. In the
1221 >Outlook Express</SPAN
1222 > (see above), OE uses
1223 IE anyway, and there is no way for <SPAN
1227 be able to distinguish between them (nor could any other proxy type application for
1230 > For a good discussion of some of the issues involved (including privacy and
1231 security issues), see
1233 HREF="http://sourceforge.net/tracker/?func=detail&atid=211118&aid=629518&group_id=11118"
1235 >http://sourceforge.net/tracker/?func=detail&atid=211118&aid=629518&group_id=11118</A
1243 NAME="SNEAKY-COOKIES"
1244 >3.23. I sometimes notice cookies sneaking through. How?</A
1248 HREF="http://en.wikipedia.org/wiki/Browser_cookie"
1252 set in several ways. The classic method is via the
1256 > HTTP header. This is straightforward, and an
1257 easy one to manipulate, such as the <SPAN
1262 HREF="../user-manual/actions-file.html#SESSION-COOKIES-ONLY"
1264 >session-cookies-only</A
1266 There is also the possibility of using
1268 HREF="http://en.wikipedia.org/wiki/Javascript"
1277 >content-cookies</TT
1279 is trickier because the syntax can vary widely, and thus requires a certain
1280 amount of guesswork. It is not realistic to catch all of these short of
1281 disabling Javascript, which would break many sites. And lastly, if the
1282 cookies are embedded in a HTTPS/SSL secure session via Javascript, they are beyond
1291 > can help manage cookies in general, can help minimize
1292 the loss of privacy posed by cookies, but can't realistically stop all
1301 >3.24. Are all cookies bad? Why?</A
1304 > No, in fact there are many beneficial uses of
1306 HREF="http://en.wikipedia.org/wiki/Browser_cookie"
1309 >. Cookies are just a
1310 method that browsers can use to store data between pages, or between browser
1311 sessions. Sometimes there is a good reason for this, and the user's life is a
1312 bit easier as a result. But there is a long history of some websites taking
1313 advantage of this layer of trust, and using the data they glean from you and
1314 your browsing habits for their own purposes, and maybe to your potential
1315 detriment. Such sites are using you and storing their data on your system.
1316 That is why the privacy conscious watch from whom those cookies come, and why
1327 HREF="http://en.wikipedia.org/wiki/Browser_cookie"
1338 NAME="ALLOW-COOKIES"
1339 >3.25. How can I allow permanent cookies for my trusted sites?</A
1342 > There are several actions that relate to cookies. The default behavior is to
1345 >"session cookies"</SPAN
1346 >, which means the cookies only last
1347 for the current browser session. This eliminates most kinds of abuse related
1348 to cookies. But there may be cases where you want cookies to last.</P
1350 > To disable all cookie actions, so that cookies are allowed unrestricted,
1351 both in and out, for <TT
1364 > { -crunch-incoming-cookies -crunch-outgoing-cookies -session-cookies-only -filter{content-cookies} }
1371 > Place the above in <TT
1374 >. Note that some of these may
1375 be off by default anyway, so this might be redundant, but there is no harm
1376 being explicit in what you want to happen. <TT
1380 includes an alias for this situation, called
1383 >allow-all-cookies</TT
1392 >3.26. Can I have separate configurations for different users?</A
1395 > Each instance of <SPAN
1399 configuration, including such attributes as the TCP port that it listens on.
1400 What you can do is run multiple instances of <SPAN
1406 HREF="../user-manual/config.html#LISTEN-ADDRESS"
1410 configuration setting, and configuration path, and then
1411 each of these can have their own configurations. Think of it as per-port
1415 Simple enough for a few users, but for large installations, consider having
1416 groups of users that might share like configurations.</P
1424 >3.27. Can I set-up Privoxy as a whitelist of
1431 > Sure. There are a couple of things you can do for simple white-listing.
1432 Here's one real easy one:</P
1441 > ############################################################
1443 ############################################################
1445 HREF="../user-manual/actions-file.html#BLOCK"
1449 / # Block *all* URLs
1451 ############################################################
1453 ############################################################
1455 HREF="../user-manual/actions-file.html#BLOCK"
1461 games.example.com</PRE
1466 > This allows access to only those three sites by first blocking all URLs, and
1467 then subsequently allowing three specific exceptions.</P
1469 > Another approach is <SPAN
1476 > concept, which incorporates the notion of
1479 >"trusted referrers"</SPAN
1481 HREF="../user-manual/config.html#TRUSTFILE"
1483 >Trust documentation</A
1487 > These are fairly simple approaches and are not completely foolproof. There
1488 are various other configuration options that should be disabled (described
1489 elsewhere here and in <A
1490 HREF="../user-manual/"
1494 so that users can't modify their own configuration and easily circumvent the
1503 >3.28. How can I turn off ad-blocking?</A
1506 > Ad blocking is achieved through a complex application of various <SPAN
1511 HREF="../user-manual/actions-file.html"
1515 actions are deployed against simple images, banners, flash animations,
1516 text pages, JavaScript, pop-ups and pop-unders, etc., so its not as simple as
1517 just turning one or two actions off. The various actions that make up
1521 > ad blocking are hard-coded into the default configuration files. It
1522 has been assumed that everyone using <SPAN
1525 > is interested in this
1529 > If you want to do without this, there are several approaches you can take:
1530 You can manually undo the many block rules in
1534 >. Or even easier, just create your own
1538 > file from scratch without the many ad
1539 blocking rules, and corresponding exceptions. Or lastly, if you are not
1540 concerned about the additional blocks that are done for privacy reasons, you
1541 can very easily over-ride <SPAN
1548 following very simple rule in your <TT
1562 > # Unblock everybody, everywhere
1564 HREF="../user-manual/actions-file.html#BLOCK"
1568 / # UN-Block *all* URLs</PRE
1575 Or even a more comprehensive reversing of various ad related actions:</P
1585 > # Unblock everybody, everywhere, and turn off appropriate filtering, etc
1587 HREF="../user-manual/actions-file.html#BLOCK"
1592 HREF="../user-manual/actions-file.html#FILTER-BANNERS-BY-SIZE"
1594 >-filter{banners-by-size}</A
1597 HREF="../user-manual/actions-file.html#FILTER-BANNERS-BY-LINK"
1599 >-filter{banners-by-link}</A
1606 / # UN-Block *all* URLs and allow ads</PRE
1615 > in this compound statement,
1620 HREF="../user-manual/actions-file.html#ALIASES"
1624 various pop-up blocking features.</P
1632 >3.29. How can I have custom template pages, like the
1648 > are specialized text files utilized by
1652 > for various purposes and can easily be modified using any text
1653 editor. All the template pages are installed in a sub-directory appropriately
1657 >. Knowing something about HTML syntax
1658 will of course be helpful.</P
1660 > Be forewarned that the default templates are subject to being overwritten
1661 during upgrades. You can, however, create completely new templates,
1662 place them in another directory and specify the alternate path in the main
1666 >. For details, have a look at the <A
1667 HREF="../user-manual/config.html#templdir"
1678 >3.30. How can I remove the <SPAN
1680 >"Go There Anyway"</SPAN
1691 > There is more than one way to do it (although Perl is not involved).</P
1693 > Editing the BLOCKED template page (see above) may dissuade some users, but
1694 this method is easily circumvented. Where you need this level of control, you
1695 might want to build <SPAN
1698 > from source, and disable various features that are
1699 available as compile-time options. You should
1703 > the sources as follows:</P
1713 > ./configure --disable-toggle --disable-editor --disable-force</PRE
1719 > This will create an executable with hard-coded security features so that
1723 > does not allow easy bypassing of blocked sites, or changing the
1724 current configuration via any connected user's web browser.</P
1726 > Finally, all of these features can also be toggled on/off via options in
1731 HREF="../user-manual/config.html#ACCESS-CONTROL"
1735 means you don't have to recompile anything.</P
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