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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
223 >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
285 >3.5. Where can I get updated Actions Files?</A
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.
323 >3.6. Can I use my old config files?</A
326 > The syntax and purpose of configuration files has remained roughly the
327 same throughout the 3.x series, but backwards compatibility is not guaranteed.
328 Also each release contains updated, <SPAN
332 therefore strongly recommended to use the newer configuration files.
341 >3.7. Why is the configuration so complicated?</A
347 > is in the eye of the beholder. Those that are
348 familiar with some of the underlying concepts, such as regular expression
349 syntax, take to it like a fish takes to water. Also, software that tries
352 >"user friendly"</SPAN
353 >, often lacks sophistication and
354 flexibility. There is always that trade-off there between power vs.
355 easy-of-use. Furthermore, anyone is welcome to contribute ideas and
356 implementations to enhance <SPAN
368 >3.8. How can I make my Yahoo/Hotmail/Gmail account work?</A
371 > The default configuration shouldn't impact the usability of any of these services.
372 It may, however, make all <A
373 HREF="http://en.wikipedia.org/wiki/Browser_cookie"
377 temporary, so that your browser will forget your
378 login credentials in between browser sessions. If you would like not to have to log
379 in manually each time you access those websites, simply turn off all cookie handling
383 > file. An example for yahoo might
395 ># Allow all cookies for Yahoo login:
398 HREF="../user-manual/actions-file.html#CRUNCH-INCOMING-COOKIES"
400 >crunch-incoming-cookies</A
402 HREF="../user-manual/actions-file.html#CRUNCH-OUTGOING-COOKIES"
404 >crunch-outgoing-cookies</A
406 HREF="../user-manual/actions-file.html#SESSION-COOKIES-ONLY"
408 >session-cookies-only</A
410 .login.yahoo.com</PRE
417 > These kinds of sites are often quite complex and heavy with
419 HREF="http://en.wikipedia.org/wiki/Javascript"
434 HREF="../user-manual/actions-file.html#ALIASES"
449 ># Gmail is a _fragile_ site:
463 > Be sure to flush your browser's caches whenever making these kinds of
464 changes, just to make sure the changes <SPAN
470 > Make sure the domain, host and path are appropriate as well. Your browser can
471 tell you where you are specifically and you should use that information for
472 your configuration settings. Note that above it is not referenced as
476 >, which is a valid domain name.
485 >3.9. What's the difference between the
501 > is not entirely trivial. To
502 help you get started, we provide you with three different default action
506 > in the web based actions file editor at <A
507 HREF="http://config.privoxy.org/show-status"
509 >http://config.privoxy.org/show-status</A
512 HREF="../user-manual/actions-file.html"
519 > for a list of actions, and how the default
523 > Where the defaults are likely to break some sites, exceptions for
527 > sites are included, but in
528 general, the more aggressive your default settings are, the more exceptions
529 you will have to make later. New users are best to start off in
533 > setting. This is safest and will have the fewest
535 HREF="../user-manual/index.html"
542 for a more detailed discussion.</P
544 > It should be noted that the <SPAN
547 > profile (formerly known
550 >"Adventuresome"</SPAN
552 aggressive, and will make use of some of
556 > advanced features. Use at your own risk!</P
564 >3.10. Why can I change the configuration
565 with a browser? Does that not raise security issues?</A
568 > It may seem strange that regular users can edit the config files with their
569 browsers, although the whole <TT
573 belongs to the user <SPAN
576 >, with only 644 permissions.
579 > When you use the browser-based editor, <SPAN
583 itself is writing to the config files. Because
587 > is running as the user <SPAN
591 it can update its own config files.
597 > for multiple untrusted users (e.g. in
598 a LAN), you will probably want to make sure that the turn the web-based
599 editor and remote toggle features are <SPAN
607 HREF="../user-manual/config.html#ENABLE-EDIT-ACTIONS"
609 >enable-edit-actions</A
618 HREF="../user-manual/config.html#ENABLE-REMOTE-TOGGLE"
620 >enable-remote-toggle</A
625 HREF="../user-manual/config.html"
627 >main configuration file</A
631 > Note that in the default configuration, only local users (i.e. those on
635 >) can connect to <SPAN
639 so this is (normally) not a security problem.
648 >3.11. What is the <TT
651 > file? What is a <SPAN
658 HREF="../user-manual/filter-file.html"
671 > as supplied by the developers are defined.
672 Filters are a special subset of actions that can be used to modify or
673 remove, web page content on the fly. Filters apply to <SPAN
680 in the page source (and optionally both client and server headers), including
681 HTML tags, and JavaScript. Regular expressions are used to accomplish this.
682 There are a number of pre-defined filters to deal with common annoyances. The
683 filters are only defined here, to invoke them, you need to use the
685 HREF="../user-manual/actions-file.html#FILTER"
692 > in one of the actions files. Filtering is automatically
693 disabled for inappropriate MIME types.</P
695 > If you are familiar with regular expressions, and HTML, you can look at
699 > with a text editor and define
700 your own filters. This is potentially a very powerful feature, but
701 requires some expertise in both regular expressions and HTML/HTTP.
703 place any modifications to the default filters, or any new ones you create
704 in a separate file, such as <TT
708 be overwritten during upgrades.
709 The ability to define multiple filter files
713 > is a new feature as of v. 3.0.5.</P
715 > There is no GUI editor option for this part of the configuration,
716 but you can disable/enable the various pre-defined filters of the included
721 HREF="http://config.privoxy.org/show-status"
723 >web-based actions file editor</A
732 >3.12. How can I set up Privoxy to act as a proxy for my
739 > only responds to requests
743 > (localhost). To have it act as a server for
744 a network, this needs to be changed in the <A
745 HREF="../user-manual/config.html"
747 >main configuration file</A
752 HREF="../user-manual/config.html#LISTEN-ADDRESS"
757 option, which may be commented out with a <SPAN
761 it is uncommented, and assign it the address of the LAN gateway interface,
762 and port number to use. Assuming your LAN address is 192.168.1.1 and you
766 > on port 8118, this line
777 > listen-address 192.168.1.1:8118</PRE
783 > Save the file, and restart <SPAN
787 all browsers on the network then to use this address and port number.</P
789 > Alternately, you can have <SPAN
793 all available interfaces:</P
803 > listen-address :8118</PRE
814 HREF="../user-manual/config.html#PERMIT-ACCESS"
818 feature to limit connections. A firewall in this situation is recommended
821 > The above steps should be the same for any TCP network, regardless of
827 > on a LAN with untrusted users,
828 we recommend that you double-check the <A
829 HREF="../user-manual/config.html#ACCESS-CONTROL"
831 >access control and security</A
841 >3.13. Instead of ads, now I get a checkerboard pattern. I don't want to see anything.</A
844 > The replacement for blocked images can be controlled with the <A
845 HREF="../user-manual/actions-file.html#SET-IMAGE-BLOCKER"
849 >set-image-blocker</TT
852 >. You have the choice of a checkerboard pattern, a transparent 1x1 GIF
856 >), or a redirect to a custom image of your choice.
857 Note that this choice only has effect for images which are blocked as images, i.e.
858 whose URLs match both a <TT
861 HREF="../user-manual/actions-file.html#HANDLE-AS-IMAGE"
875 HREF="../user-manual/actions-file.html#BLOCK"
881 > If you want to see nothing, then change the <A
882 HREF="../user-manual/actions-file.html#SET-IMAGE-BLOCKER"
886 >set-image-blocker</TT
892 >. This can be done by editing the
896 > file, or through the <A
897 HREF="http://config.privoxy.org/show-status"
899 >web-based actions file editor</A
908 >3.14. Why would anybody want to see a checkerboard pattern?</A
912 HREF="general.html#WHATSANAD"
913 >telling which image is an ad and which
915 >, is an educated guess. While we hope that the standard configuration
916 is rather smart, it will make occasional mistakes. The checkerboard image is visually
917 decent, and it shows you where images have been blocked, which can be very
918 helpful in case some navigation aid or otherwise innocent image was
919 erroneously blocked. It is recommended for new users so they can
923 > what is happening. Some people might also enjoy seeing how
924 many banners they <SPAN
938 >3.15. I see some images being replaced with text
939 instead of the checkerboard image. Why and how do I get rid of this?</A
942 > This happens when the banners are not embedded in the HTML code of the
943 page itself, but in separate HTML (sub)documents that are loaded into (i)frames
944 or (i)layers, and these external HTML documents are blocked. Being non-images
945 they get replaced by a substitute HTML page rather than a substitute image,
946 which wouldn't work out technically, since the browser expects and accepts
947 only HTML when it has requested an HTML document. </P
949 > The substitute page adapts to the available space and shows itself as a
950 miniature two-liner if loaded into small frames, or full-blown with a
951 large red "BLOCKED" banner if space allows.</P
953 > If you prefer the banners to be blocked by images, you must see to it that
954 the HTML documents in which they are embedded are not blocked. Clicking
958 > link offered in the substitute page will show
959 you which rule blocked the page. After changing the rule and un-blocking
960 the HTML documents, the browser will try to load the actual banner images
961 and the usual image blocking will (hopefully!) kick in.</P
969 >3.16. Can Privoxy run as a service
973 > Yes. Version 3.0.5 introduces full <SPAN
977 functionality. See <A
978 HREF="../user-manual/installation.html#installation-pack-win"
984 > for details on how to install and configure
990 > Earlier 3.x versions could run as a system service using <B
994 See the discussion at <A
995 HREF="http://sourceforge.net/tracker/?func=detail&atid=361118&aid=485617&group_id=11118"
997 >http://sourceforge.net/tracker/?func=detail&atid=361118&aid=485617&group_id=11118</A
999 for details, and a sample configuration.</P
1007 >3.17. How can I make Privoxy work with other
1008 proxies like Squid or Tor?</A
1011 > This can be done and is often useful to combine the benefits of
1015 > with those of a another proxy.
1017 HREF="../user-manual/config.html#FORWARDING"
1019 >forwarding chapter</A
1022 HREF="../user-manual/index.html"
1026 describes how to do this, and the <A
1027 HREF="misc.html#TOR"
1028 > How do I use Privoxy together with
1038 >3.18. Can I just set Privoxy to use port 80
1039 and thus avoid individual browser configuration?</A
1042 > No, its more complicated than that. This only works with special kinds
1043 of proxies known as <SPAN
1045 >"intercepting"</SPAN
1046 > proxies (see below).</P
1054 >3.19. Can Privoxy run as a <SPAN
1056 >"transparent"</SPAN
1060 > The whole idea of Privoxy is to modify client requests
1061 and server responses in all sorts of ways and therefore
1062 it's not a transparent proxy as described in
1064 HREF="http://tools.ietf.org/html/rfc2616"
1069 > However, some people say <SPAN
1071 >"transparent proxy"</SPAN
1075 >"intercepting proxy"</SPAN
1076 >. If you are one of them,
1078 HREF="#intercepting"
1089 >3.20. Can Privoxy run as a <SPAN
1091 >"intercepting"</SPAN
1098 > can't intercept traffic itself,
1099 but it can handle requests that where intercepted and redirected
1100 with a packet filter (like <SPAN
1107 >), as long as the <TT
1117 > header is required by HTTP/1.1 and as most
1118 web sites don't work if it isn't set, this limitation shouldn't be a
1121 > Please refer to your packet filter's documentation to learn how to
1122 intercept and redirect traffic into <SPAN
1125 >. Afterward you just have
1131 HREF="../user-manual/config.html#ACCEPT-INTERCEPTED-REQUESTS"
1133 >accept intercepted requests</A
1142 >3.21. How can I configure Privoxy for use with Outlook
1148 >Outlook Express</SPAN
1151 >Internet Explorer</SPAN
1153 components to both render HTML, and fetch any HTTP requests that may be embedded in an HTML email.
1154 So however you have <SPAN
1157 > configured to work
1158 with IE, this configuration should automatically be shared.</P
1166 >3.22. How can I have separate rules just for HTML mail?</A
1169 > The short answer is, you can't. <SPAN
1173 of knowing which particular application makes a request, so there is no way to
1174 distinguish between web pages and HTML mail.
1178 > just blindly proxies all requests. In the
1181 >Outlook Express</SPAN
1182 > (see above), OE uses
1183 IE anyway, and there is no way for <SPAN
1187 be able to distinguish between them (nor could any other proxy type application for
1190 > For a good discussion of some of the issues involved (including privacy and
1191 security issues), see
1193 HREF="http://sourceforge.net/tracker/?func=detail&atid=211118&aid=629518&group_id=11118"
1195 >http://sourceforge.net/tracker/?func=detail&atid=211118&aid=629518&group_id=11118</A
1203 NAME="SNEAKY-COOKIES"
1204 >3.23. I sometimes notice cookies sneaking through. How?</A
1208 HREF="http://en.wikipedia.org/wiki/Browser_cookie"
1212 set in several ways. The classic method is via the
1216 > HTTP header. This is straightforward, and an
1217 easy one to manipulate, such as the <SPAN
1222 HREF="../user-manual/actions-file.html#SESSION-COOKIES-ONLY"
1224 >session-cookies-only</A
1226 There is also the possibility of using
1228 HREF="http://en.wikipedia.org/wiki/Javascript"
1237 >content-cookies</TT
1239 is trickier because the syntax can vary widely, and thus requires a certain
1240 amount of guesswork. It is not realistic to catch all of these short of
1241 disabling Javascript, which would break many sites. And lastly, if the
1242 cookies are embedded in a HTTPS/SSL secure session via Javascript, they are beyond
1251 > can help manage cookies in general, can help minimize
1252 the loss of privacy posed by cookies, but can't realistically stop all
1261 >3.24. Are all cookies bad? Why?</A
1264 > No, in fact there are many beneficial uses of
1266 HREF="http://en.wikipedia.org/wiki/Browser_cookie"
1269 >. Cookies are just a
1270 method that browsers can use to store data between pages, or between browser
1271 sessions. Sometimes there is a good reason for this, and the user's life is a
1272 bit easier as a result. But there is a long history of some websites taking
1273 advantage of this layer of trust, and using the data they glean from you and
1274 your browsing habits for their own purposes, and maybe to your potential
1275 detriment. Such sites are using you and storing their data on your system.
1276 That is why the privacy conscious watch from whom those cookies come, and why
1287 HREF="http://en.wikipedia.org/wiki/Browser_cookie"
1298 NAME="ALLOW-COOKIES"
1299 >3.25. How can I allow permanent cookies for my trusted sites?</A
1302 > There are several actions that relate to cookies. The default behavior is to
1305 >"session cookies"</SPAN
1306 >, which means the cookies only last
1307 for the current browser session. This eliminates most kinds of abuse related
1308 to cookies. But there may be cases where you want cookies to last.</P
1310 > To disable all cookie actions, so that cookies are allowed unrestricted,
1311 both in and out, for <TT
1324 > { -crunch-incoming-cookies -crunch-outgoing-cookies -session-cookies-only -filter{content-cookies} }
1331 > Place the above in <TT
1334 >. Note that some of these may
1335 be off by default anyway, so this might be redundant, but there is no harm
1336 being explicit in what you want to happen. <TT
1340 includes an alias for this situation, called
1343 >allow-all-cookies</TT
1352 >3.26. Can I have separate configurations for different users?</A
1355 > Each instance of <SPAN
1359 configuration, including such attributes as the TCP port that it listens on.
1360 What you can do is run multiple instances of <SPAN
1366 HREF="../user-manual/config.html#LISTEN-ADDRESS"
1370 configuration setting, and configuration path, and then
1371 each of these can have their own configurations. Think of it as per-port
1375 Simple enough for a few users, but for large installations, consider having
1376 groups of users that might share like configurations.</P
1384 >3.27. Can I set-up Privoxy as a whitelist of
1391 > Sure. There are a couple of things you can do for simple white-listing.
1392 Here's one real easy one:</P
1401 > ############################################################
1403 ############################################################
1405 HREF="../user-manual/actions-file.html#BLOCK"
1409 / # Block *all* URLs
1411 ############################################################
1413 ############################################################
1415 HREF="../user-manual/actions-file.html#BLOCK"
1421 games.example.com</PRE
1426 > This allows access to only those three sites by first blocking all URLs, and
1427 then subsequently allowing three specific exceptions.</P
1429 > A more interesting approach is <SPAN
1436 > concept, which incorporates the notion of
1439 >"trusted referrers"</SPAN
1441 HREF="../user-manual/config.html#TRUSTFILE"
1443 >User Manual Trust</A
1447 > These are fairly simple approaches and are not completely foolproof. There
1448 are various other configuration options that should be disabled (described
1449 elsewhere here and in <A
1450 HREF="../user-manual/"
1454 so that users can't modify their own configuration and easily circumvent the
1463 >3.28. How can I turn off ad-blocking?</A
1466 > Ad blocking is achieved through a complex application of various <SPAN
1471 HREF="../user-manual/actions-file.html"
1475 actions are deployed against simple images, banners, flash animations,
1476 text pages, JavaScript, pop-ups and pop-unders, etc., so its not as simple as
1477 just turning one or two actions off. The various actions that make up
1481 > ad blocking are hard-coded into the default configuration files. It
1482 has been assumed that everyone using <SPAN
1485 > is interested in this
1489 > If you want to do without this, there are several approaches you can take:
1490 You can manually undo the many block rules in
1494 >. Or even easier, just create your own
1498 > file from scratch without the many ad
1499 blocking rules, and corresponding exceptions. Or lastly, if you are not
1500 concerned about the additional blocks that are done for privacy reasons, you
1501 can very easily over-ride <SPAN
1508 following very simple rule in your <TT
1522 > # Unblock everybody, everywhere
1524 HREF="../user-manual/actions-file.html#BLOCK"
1528 / # UN-Block *all* URLs</PRE
1535 Or even a more comprehensive reversing of various ad related actions:</P
1545 > # Unblock everybody, everywhere, and turn off appropriate filtering, etc
1547 HREF="../user-manual/actions-file.html#BLOCK"
1552 HREF="../user-manual/actions-file.html#FILTER-BANNERS-BY-SIZE"
1554 >-filter{banners-by-size}</A
1557 HREF="../user-manual/actions-file.html#FILTER-BANNERS-BY-LINK"
1559 >-filter{banners-by-link}</A
1566 / # UN-Block *all* URLs and allow ads</PRE
1575 > in this compound statement,
1580 HREF="../user-manual/actions-file.html#ALIASES"
1584 various pop-up blocking features.</P
1592 >3.29. How can I have custom template pages, like the
1608 > are specialized text files utilized by
1612 > for various purposes and can easily be modified using any text
1613 editor. All the template pages are installed in a sub-directory appropriately
1617 >. Knowing something about HTML syntax
1618 will of course be helpful. You cannot rename any of these files, or create
1619 completely new templates, that is not possible. But you can change the page
1620 content to whatever you like. Be forewarned that these files are subject to
1621 being overwritten during upgrades, so be sure to save any customizations.</P
1629 >3.30. How can I remove the <SPAN
1631 >"Go There Anyway"</SPAN
1642 > There is more than one way to do it.</P
1644 > Editing the BLOCKED template page (see above) may dissuade some users, but
1645 this method is easily circumvented. Where you need this level of control, you
1649 > from source, and enable various features that are
1650 available as compile-time options. You should
1654 > the sources as follows:</P
1664 > ./configure --disable-toggle --disable-editor --disable-force</PRE
1670 > This will create an executable with hard-coded security features so that
1674 > does not allow easy bypassing of blocked sites, or changing the
1675 current configuration via any connected user's web browser.</P
1677 > Note that all of these features can also be toggled on/off via options in
1682 HREF="../user-manual/config.html#ACCESS-CONTROL"
1686 means you don't have to recompile anything.</P
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