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40 >Privoxy Frequently Asked Questions</TH
48 HREF="installation.html"
86 >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
152 > 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
188 >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
224 >3.4. There are several different <SPAN
230 > Three actions files
231 are being included by the developers, to be used for
232 different purposes: These are
240 which is actively maintained by the <SPAN
244 developers and typically sets the default policies, <TT
247 >, where users are encouraged
248 to make their private customizations, and <TT
252 which is for internal <SPAN
257 HREF="../user-manual/actions-file.html"
259 >the actions chapter</A
262 HREF="../user-manual/index.html"
266 detailed explanation.</P
268 > Earlier versions included three different versions of the
272 > file. The new scheme allows for
273 greater flexibility of local configuration, and for browser based
274 selection of pre-defined <SPAN
276 >"aggressiveness"</SPAN
286 >3.5. Where can I get updated Actions Files?</H3
288 > Based on your feedback and the continuing development, updates of
293 made available from time to time on the <A
294 HREF="http://sourceforge.net/project/showfiles.php?group_id=11118"
299 HREF="http://sf.net/projects/ijbswa/"
305 > If you wish to receive an email notification whenever we release updates of
309 > or the actions file, <A
310 HREF="http://lists.sourceforge.net/lists/listinfo/ijbswa-announce/"
313 to our announce mailing list</A
314 >, ijbswa-announce@lists.sourceforge.net.
324 >3.6. Can I use my old config files?</H3
326 > The syntax and purpose of configuration files has remained the same
327 throughout the 3.x series. Although each release contains updated,
331 > versions and it is recommended to use the newer
334 If upgrading from version prior to 3.0.4 the syntax for <TT
338 has changed. See the <A
339 HREF="../user-manual/whatsnew.html"
341 >What's New section</A
349 > But all configuration files have substantially
350 changed from the <SPAN
357 >. The old files, like
361 > will not work at all.
365 HREF="../user-manual/whatsnew.html"
369 page for information on configuration changes that may occur from one release to another.
379 >3.7. Why is the configuration so complicated?</H3
384 > is in the eye of the beholder. Those that are
385 familiar with some of the underlying concepts, such as regular expression
386 syntax, take to it like a fish takes to water. Also, software that tries
389 >"user friendly"</SPAN
390 >, often lacks sophistication and
391 flexibility. There is always that trade-off there between power vs.
392 easy-of-use. Furthermore, anyone is welcome to contribute ideas and
393 implementations to enhance <SPAN
406 >3.8. How can I make my Yahoo/Hotmail/Gmail account work?</H3
408 > The default configuration shouldn't impact the usability of any of these services.
409 It may, however, make all <A
410 HREF="http://en.wikipedia.org/wiki/Browser_cookie"
414 temporary, so that your browser will forget your
415 login credentials in between browser sessions. If you would like not to have to log
416 in manually each time you access those websites, simply turn off all cookie handling
420 > file. An example for yahoo might
432 ># Allow all cookies for Yahoo login:
435 HREF="../user-manual/actions-file.html#CRUNCH-INCOMING-COOKIES"
437 >crunch-incoming-cookies</A
439 HREF="../user-manual/actions-file.html#CRUNCH-OUTGOING-COOKIES"
441 >crunch-outgoing-cookies</A
443 HREF="../user-manual/actions-file.html#SESSION-COOKIES-ONLY"
445 >session-cookies-only</A
447 .login.yahoo.com</PRE
454 > These kinds of sites are often quite complex and heavy with
456 HREF="http://en.wikipedia.org/wiki/Javascript"
471 HREF="../user-manual/actions-file.html#ALIASES"
486 ># Gmail is a _fragile_ site:
500 > Be sure to flush your browser's caches whenever making these kinds of
501 changes, just to make sure the changes <SPAN
507 > Make sure the domain, host and path are appropriate as well. Your browser can
508 tell you where you are specifically and you should use that information for
509 your configuration settings. Note that above it is not referenced as
513 >, which is a valid domain name.
523 >3.9. What's the difference between the
538 > is not entirely trivial. To
539 help you get started, we provide you with three different default action
543 > in the web based actions file editor at <A
544 HREF="http://config.privoxy.org/show-status"
546 >http://config.privoxy.org/show-status</A
549 HREF="../user-manual/actions-file.html"
556 > for a list of actions, and how the default
560 > Where the defaults are likely to break some sites, exceptions for
564 > sites are included, but in
565 general, the more aggressive your default settings are, the more exceptions
566 you will have to make later. New users are best to start off in
570 > setting. This is safest and will have the fewest
572 HREF="../user-manual/index.html"
579 for a more detailed discussion.</P
581 > It should be noted that the <SPAN
584 > profile (formerly known
587 >"Adventuresome"</SPAN
589 aggressive, and will make use of some of
593 > advanced features. Use at your own risk!</P
602 >3.10. Why can I change the configuration
603 with a browser? Does that not raise security issues?</H3
605 > It may seem strange that regular users can edit the config files with their
606 browsers, although the whole <TT
610 belongs to the user <SPAN
613 >, with only 644 permissions.
616 > When you use the browser-based editor, <SPAN
620 itself is writing to the config files. Because
624 > is running as the user <SPAN
628 it can update the config files.
634 > for multiple untrusted users (e.g. in
635 a LAN), you will probably want to turn the web-based editor and remote toggle
636 features off by setting <SPAN
641 HREF="../user-manual/config.html#ENABLE-EDIT-ACTIONS"
643 >enable-edit-actions</A
652 HREF="../user-manual/config.html#ENABLE-REMOTE-TOGGLE"
654 >enable-remote-toggle</A
659 HREF="../user-manual/config.html"
661 >main configuration file</A
665 > Note that in the default configuration, only local users (i.e. those on
669 >) can connect to <SPAN
673 so this is not (normally) a security problem.
683 >3.11. What is the <TT
686 > file? What is a <SPAN
692 HREF="../user-manual/filter-file.html"
705 > as supplied by the developers are defined.
706 Filters are a special subset of actions that can be used to modify or
707 remove, web page content on the fly. Filters apply to <SPAN
714 in the page source (and optionally both client and server headers), including
715 HTML tags, and JavaScript. Regular expressions are used to accomplish this.
716 There are a number of pre-defined filters to deal with common annoyances. The
717 filters are only defined here, to invoke them, you need to use the
719 HREF="../user-manual/actions-file.html#FILTER"
726 > in one of the actions files. Filtering is automatically
727 disabled for inappropriate MIME types.</P
729 > If you are familiar with regular expressions, and HTML, you can look at
733 > with a text editor and define
734 your own filters. This is potentially a very powerful feature, but
735 requires some expertise in both regular expressions and HTML/HTTP.
737 place any modifications to the default filters, or any new ones you create
738 in a separate file, such as <TT
742 be overwritten during upgrades.
743 The ability to define multiple filter files
747 > is a new feature as of v. 3.0.5.</P
749 > There is no GUI editor option for this part of the configuration,
750 but you can disable/enable the various pre-defined filters of the included
755 HREF="http://config.privoxy.org/show-status"
757 >web-based actions file editor</A
767 >3.12. How can I set up Privoxy to act as a proxy for my
773 > only responds to requests
777 > (localhost). To have it act as a server for
778 a network, this needs to be changed in the <A
779 HREF="../user-manual/config.html"
781 >main configuration file</A
786 HREF="../user-manual/config.html#LISTEN-ADDRESS"
791 option, which may be commented out with a <SPAN
795 it is uncommented, and assign it the address of the LAN gateway interface,
796 and port number to use. Assuming your LAN address is 192.168.1.1 and you
800 > on port 8118, this line
811 > listen-address 192.168.1.1:8118</PRE
817 > Save the file, and restart <SPAN
821 all browsers on the network then to use this address and port number.</P
823 > Alternately, you can have <SPAN
827 all available interfaces:</P
837 > listen-address :8118</PRE
848 HREF="../user-manual/config.html#PERMIT-ACCESS"
852 feature to limit connections. A firewall in this situation is recommended
855 > The above steps should be the same for any TCP network, regardless of
861 > on a LAN with untrusted users,
862 we recommend that you double-check the <A
863 HREF="../user-manual/config.html#ACCESS-CONTROL"
865 >access control and security</A
876 >3.13. Instead of ads, now I get a checkerboard pattern. I don't want to see anything.</H3
878 > The replacement for blocked images can be controlled with the <A
879 HREF="../user-manual/actions-file.html#SET-IMAGE-BLOCKER"
883 >set-image-blocker</TT
886 >. You have the choice of a checkerboard pattern, a transparent 1x1 GIF
890 >), or a redirect to a custom image of your choice.
891 Note that this choice only has effect for images which are blocked as images, i.e.
892 whose URLs match both a <TT
895 HREF="../user-manual/actions-file.html#HANDLE-AS-IMAGE"
909 HREF="../user-manual/actions-file.html#BLOCK"
915 > If you want to see nothing, then change the <A
916 HREF="../user-manual/actions-file.html#SET-IMAGE-BLOCKER"
920 >set-image-blocker</TT
926 >. This can be done by editing the
930 > file, or through the <A
931 HREF="http://config.privoxy.org/show-status"
933 >web-based actions file editor</A
943 >3.14. Why would anybody want to see a checkerboard pattern?</H3
946 HREF="general.html#WHATSANAD"
947 >telling which image is an ad and which
949 >, is an educated guess. While we hope that the standard configuration
950 is rather smart, it will make occasional mistakes. The checkerboard image is visually
951 decent, and it shows you where images have been blocked, which can be very
952 helpful in case some navigation aid or otherwise innocent image was
953 erroneously blocked. It is recommended for new users so they can
957 > what is happening. Some people might also enjoy seeing how
958 many banners they <SPAN
973 >3.15. I see some images being replaced by a text
974 instead of the checkerboard image. Why and how do I get rid of this?</H3
976 > This happens when the banners are not embedded in the HTML code of the
977 page itself, but in separate HTML (sub)documents that are loaded into (i)frames
978 or (i)layers, and these external HTML documents are blocked. Being non-images
979 they get replaced by a substitute HTML page rather than a substitute image,
980 which wouldn't work out technically, since the browser expects and accepts
981 only HTML when it has requested an HTML document. </P
983 > The substitute page adapts to the available space and shows itself as a
984 miniature two-liner if loaded into small frames, or full-blown with a
985 large red "BLOCKED" banner if space allows.</P
987 > If you prefer the banners to be blocked by images, you must see to it that
988 the HTML documents in which they are embedded are not blocked. Clicking
992 > link offered in the substitute page will show
993 you which rule blocked the page. After changing the rule and un-blocking
994 the HTML documents, the browser will try to load the actual banner images
995 and the usual image blocking will (hopefully!) kick in.</P
1004 >3.16. Can Privoxy run as a service
1007 > Yes. Version 3.0.5 introduces full <SPAN
1011 functionality. See <A
1012 HREF="../user-manual/installation.html#installation-pack-win"
1018 > for details on how to install and configure
1024 > Earlier 3.x versions could run as a system service using <B
1028 See the discussion at <A
1029 HREF="http://sourceforge.net/tracker/?func=detail&atid=361118&aid=485617&group_id=11118"
1031 >http://sourceforge.net/tracker/?func=detail&atid=361118&aid=485617&group_id=11118</A
1033 for details, and a sample configuration.</P
1042 >3.17. How can I make Privoxy work with other
1043 proxies like Squid or Tor?</H3
1045 > This can be done and is often useful to combine the benefits of
1049 > with those of a another proxy.
1051 HREF="../user-manual/config.html#FORWARDING"
1053 >forwarding chapter</A
1056 HREF="../user-manual/index.html"
1060 describes how to do this, and the <A
1061 HREF="misc.html#TOR"
1062 > How do I use Privoxy together with
1073 >3.18. Can I just set Privoxy to use port 80
1074 and thus avoid individual browser configuration?</H3
1076 > No, its more complicated than that. This only works with special kinds
1077 of proxies known as <SPAN
1079 >"transparent"</SPAN
1080 > proxies (see below).</P
1089 >3.19. Can Privoxy run as a <SPAN
1091 >"transparent"</SPAN
1097 > currently does not have this ability,
1098 though it may be added in a future release. Transparent proxies require
1099 special handling of the request headers beyond what
1103 > is now capable of. </P
1108 > behind another proxy that has
1109 this ability should work though.
1111 HREF="../user-manual/config.html#FORWARDING"
1113 >forwarding chapter</A
1116 HREF="../user-manual/index.html"
1120 a transparent proxy to be used for chaining we suggest Transproxy
1122 HREF="http://transproxy.sourceforge.net/"
1124 >http://transproxy.sourceforge.net/</A
1134 >3.20. How can I configure Privoxy for use with Outlook
1139 >Outlook Express</SPAN
1142 >Internet Explorer</SPAN
1144 components to both render HTML, and fetch any HTTP requests that may be embedded in an HTML email.
1145 So however you have <SPAN
1148 > configured to work
1149 with IE, this configuration should automatically be shared.</P
1158 >3.21. How can I have separate rules just for HTML mail?</H3
1160 > The short answer is, you can't. <SPAN
1164 of knowing which particular application makes a request, so there is no way to
1165 distinguish between web pages and HTML mail.
1169 > just blindly proxies all requests. In the
1172 >Outlook Express</SPAN
1173 > (see above), OE uses
1174 IE anyway, and there is no way for <SPAN
1178 be able to distinguish between them (nor could any other proxy type application for
1181 > For a good discussion of some of the issues involved (including privacy and
1182 security issues), see
1184 HREF="http://sourceforge.net/tracker/?func=detail&atid=211118&aid=629518&group_id=11118"
1186 >http://sourceforge.net/tracker/?func=detail&atid=211118&aid=629518&group_id=11118</A
1194 NAME="SNEAKY-COOKIES"
1196 >3.22. I sometimes notice cookies sneaking through. How?</H3
1199 HREF="http://en.wikipedia.org/wiki/Browser_cookie"
1203 set in several ways. The classic method is via the
1207 > HTTP header. This is straightforward, and an
1208 easy one to manipulate, such as the <SPAN
1213 HREF="../user-manual/actions-file.html#SESSION-COOKIES-ONLY"
1215 >session-cookies-only</A
1217 There is also the possibility of using
1219 HREF="http://en.wikipedia.org/wiki/Javascript"
1228 >content-cookies</TT
1230 is trickier because the syntax can vary widely, and thus requires a certain
1231 amount of guesswork. It is not realistic to catch all of these short of
1232 disabling Javascript, which would break many sites. And lastly, if the
1233 cookies are embedded in a HTTPS/SSL secure session via Javascript, they are beyond
1242 > can help manage cookies in general, can help minimize
1243 the loss of privacy posed by cookies, but can't realistically stop all
1253 >3.23. Are all cookies bad? Why?</H3
1255 > No, in fact there are many beneficial uses of
1257 HREF="http://en.wikipedia.org/wiki/Browser_cookie"
1260 >. Cookies are just a
1261 method that browsers can use to store data between pages, or between browser
1262 sessions. Sometimes there is a good reason for this, and the user's life is a
1263 bit easier as a result. But there is a long history of some websites taking
1264 advantage of this layer of trust, and using the data they glean from you and
1265 your browsing habits for their own purposes, and maybe to your potential
1266 detriment. Such sites are using you and storing their data on your system.
1267 That is why the security conscious watch from whom those cookies come, and why
1278 HREF="http://en.wikipedia.org/wiki/Browser_cookie"
1289 NAME="ALLOW-COOKIES"
1291 >3.24. How can I allow permanent cookies for my trusted sites?</H3
1293 > There are several actions that relate to cookies. The default behavior is to
1296 >"session cookies"</SPAN
1297 >, which means the cookies only last
1298 for the current browser session. This eliminates most kinds of abuse related
1299 to cookies. But there may be cases where we want cookies to last.</P
1301 > To disable all cookie actions, so that cookies are allowed unrestricted,
1302 both in and out, for <TT
1315 > { -crunch-incoming-cookies -crunch-outgoing-cookies -session-cookies-only -filter{content-cookies} }
1322 > Place the above in <TT
1325 >. Note some of these may
1326 be off by default anyway, so this might be redundant, but there is no harm
1327 being explicit in what you want to happen. <TT
1331 includes an alias for this situation, called
1334 >allow-all-cookies</TT
1344 >3.25. Can I have separate configurations for different users?</H3
1346 > Each instance of <SPAN
1350 configuration, including such attributes as the TCP port that it listens on.
1351 What you can do is run multiple instances of <SPAN
1357 HREF="../user-manual/config.html#LISTEN-ADDRESS"
1361 configuration setting, and configuration path, and then
1362 each of these can have their own configurations. Think of it as per-port
1366 Simple enough for a few users, but for large installations, consider having
1367 groups of users that might share like configurations.</P
1376 >3.26. Can I set-up Privoxy as a whitelist of
1382 > Sure. There are a couple of things you can do for simple white-listing.
1383 Here's one real easy one:</P
1392 > ############################################################
1394 ############################################################
1396 HREF="../user-manual/actions-file.html#BLOCK"
1400 / # Block *all* URLs
1402 ############################################################
1404 ############################################################
1406 HREF="../user-manual/actions-file.html#BLOCK"
1412 games.example.com</PRE
1417 > This allows access to only those three sites by first blocking all URLs, and
1418 then subsequently allowing three specific exceptions.</P
1420 > A more interesting approach is <SPAN
1427 > concept, which incorporates the notion of
1430 >"trusted referrers"</SPAN
1432 HREF="../user-manual/config.html#TRUSTFILE"
1434 >User Manual Trust</A
1438 > These are fairly simple approaches and are not completely foolproof. There
1439 are various other configuration options that should be disabled (described
1440 elsewhere here and in <A
1441 HREF="../user-manual/"
1445 so that users can't modify their own configuration and easily circumvent the
1455 >3.27. How can I turn off ad-blocking?</H3
1457 > Ad blocking is achieved through a complex application of various <SPAN
1462 HREF="../user-manual/actions-file.html"
1466 actions are deployed against simple images, banners, flash animations,
1467 text pages, JavaScript, pop-ups and pop-unders, etc., so its not as simple as
1468 just turning one or two actions off. The various actions that make up
1472 > ad blocking are hard-coded into the default configuration files. It
1473 has been assumed that everyone using <SPAN
1476 > is interested in this
1480 > If you want to do without this, there are several approaches you can take:
1481 You can manually undo the many block rules in
1485 >. Or even easier, just create your own
1489 > file from scratch without the many ad
1490 blocking rules, and corresponding exceptions. Or lastly, if you are not
1491 concerned about the additional blocks that are done for privacy reasons, you
1492 can very easily over-ride <SPAN
1499 following very simple rule in your <TT
1513 > # Unblock everybody, everywhere
1515 HREF="../user-manual/actions-file.html#BLOCK"
1519 / # UN-Block *all* URLs</PRE
1526 Or even a more comprehensive reversing of various ad related actions:</P
1536 > # Unblock everybody, everywhere, and turn off appropriate filtering, etc
1538 HREF="../user-manual/actions-file.html#BLOCK"
1543 HREF="../user-manual/actions-file.html#FILTER-BANNERS-BY-SIZE"
1545 >-filter{banners-by-size}</A
1548 HREF="../user-manual/actions-file.html#FILTER-BANNERS-BY-LINK"
1550 >-filter{banners-by-link}</A
1557 / # UN-Block *all* URLs and allow ads</PRE
1566 > in this compound statement,
1571 HREF="../user-manual/actions-file.html#ALIASES"
1575 various pop-up blocking features.</P
1584 >3.28. How can I have custom template pages, like the
1599 > are specialized text files utilized by
1603 > for various purposes and can easily be modified using any text
1604 editor. All the template pages are installed in a sub-directory appropriately
1608 >. Knowing something about HTML syntax
1609 will of course be helpful. You cannot rename any of these files, or create
1610 completely new templates, that is not possible. But you can change the page
1611 content to whatever you like. Be forewarned that these files are subject to
1612 being overwritten during upgrades, so be sure to save any customizations.</P
1621 >3.29. How can I remove the <SPAN
1623 >"Go There Anyway"</SPAN
1633 > Editing the BLOCKED template page (see above) may dissuade some users, but
1634 this method is easily circumvented. Where you need this level of control, you
1638 > from source, and enable various features that are
1639 available as compile-time options. You should
1643 > the sources as follows:</P
1653 > ./configure --disable-toggle --disable-editor --disable-force</PRE
1659 > This will create an executable with hard-coded security features so that
1663 > does not allow easy bypassing of blocked sites, or changing the
1664 current configuration via any connected user's web browser. Some of these
1665 features can also be toggled on/off via options in
1671 HREF="../user-manual/config.html#ACCESS-CONTROL"
1675 compiled-in compliance is a much better method of ensuring that a block is
1678 > Default builds of <SPAN
1681 > are typically built with these features
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1701 HREF="installation.html"