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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. How can I make my Yahoo/Hotmail/Gmail account work?</H3
381 > The default configuration shouldn't impact the usability of any of these services.
382 It will, 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:
472 > Be sure to flush your browser's caches whenever making these kinds of
473 changes, just to make sure the changes <SPAN
479 > Make sure the domain, host and path are appropriate as well. Your browser can
480 tell you where you are specifically and you should use that information for
481 your configuration settings. Note that above it is not referenced as
485 >, which is a valid domain name.
495 >3.8. What's the difference between the
510 > is not entirely trivial. To
511 help you get started, we provide you with three different default action
515 > in the web based actions file editor at <A
516 HREF="http://config.privoxy.org/show-status"
518 >http://config.privoxy.org/show-status</A
521 HREF="../user-manual/actions-file.html"
528 > for a list of actions, and how the default
532 > Where the defaults are likely to break some sites, exceptions for
536 > sites are included, but in
537 general, the more aggressive your default settings are, the more exceptions
538 you will have to make later. New users are best to start off in
542 > setting. This is safest and will have the fewest
544 HREF="../user-manual/index.html"
551 for a more detailed discussion.</P
553 > It should be noted that the <SPAN
556 > profile (formerly known
559 >"Adventuresome"</SPAN
561 aggressive, and will make use of some of
565 > advanced features. Use at your own risk!</P
574 >3.9. Why can I change the configuration
575 with a browser? Does that not raise security issues?</H3
577 > It may seem strange that regular users can edit the config files with their
578 browsers, although the whole <TT
582 belongs to the user <SPAN
585 >, with only 644 permissions.
588 > When you use the browser-based editor, <SPAN
592 itself is writing to the config files. Because
596 > is running as the user <SPAN
600 it can update the config files.
606 > for multiple untrusted users (e.g. in
607 a LAN), you will probably want to turn the web-based editor and remote toggle
608 features off by setting <SPAN
613 HREF="../user-manual/config.html#ENABLE-EDIT-ACTIONS"
615 >enable-edit-actions</A
624 HREF="../user-manual/config.html#ENABLE-REMOTE-TOGGLE"
626 >enable-remote-toggle</A
631 HREF="../user-manual/config.html"
633 >main configuration file</A
637 > Note that in the default configuration, only local users (i.e. those on
641 >) can connect to <SPAN
645 so this is not (normally) a security problem.
655 >3.10. What is the <TT
658 > 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 on the fly. Filters apply to <SPAN
686 in the page source (and optionally both client and server headers), including
687 HTML tags, and JavaScript. Regular expressions are used to accomplish this.
688 There are a number of pre-defined filters to deal with common annoyances. The
689 filters are only defined here, to invoke them, you need to use the
691 HREF="../user-manual/actions-file.html#FILTER"
698 > in one of the actions files. Filtering is automatically
699 disabled for inappropriate MIME types.</P
701 > If you are familiar with regular expressions, and HTML, you can look at
705 > with a text editor and define
706 your own filters. This is potentially a very powerful feature, but
707 requires some expertise in both regular expressions and HTML/HTTP.
709 place any modifications to the default filters, or any new ones you create
710 in a separate file, such as <TT
714 be overwritten during upgrades.
715 The ability to define multiple filter files
719 > is a new feature as of v. 3.0.5.</P
721 > There is no GUI editor option for this part of the configuration,
722 but you can disable/enable the various pre-defined filters of the included
727 HREF="http://config.privoxy.org/show-status"
729 >web-based actions file editor</A
739 >3.11. How can I set up Privoxy to act as a proxy for my
745 > only responds to requests
749 > (localhost). To have it act as a server for
750 a network, this needs to be changed in the <A
751 HREF="../user-manual/config.html"
753 >main configuration file</A
758 HREF="../user-manual/config.html#LISTEN-ADDRESS"
763 option, which may be commented out with a <SPAN
767 it is uncommented, and assign it the address of the LAN gateway interface,
768 and port number to use. Assuming your LAN address is 192.168.1.1 and you
772 > on port 8118, this line
783 > listen-address 192.168.1.1:8118</PRE
789 > Save the file, and restart <SPAN
793 all browsers on the network then to use this address and port number.</P
795 > Alternately, you can have <SPAN
799 all available interfaces:</P
809 > listen-address :8118</PRE
820 HREF="../user-manual/config.html#PERMIT-ACCESS"
824 feature to limit connections. A firewall in this situation is recommended
827 > The above steps should be the same for any TCP network, regardless of
833 > on a LAN with untrusted users,
834 we recommend that you double-check the <A
835 HREF="../user-manual/config.html#ACCESS-CONTROL"
837 >access control and security</A
848 >3.12. Instead of ads, now I get a checkerboard pattern. I don't want to see anything.</H3
850 > The replacement for blocked images can be controlled with the <A
851 HREF="../user-manual/actions-file.html#SET-IMAGE-BLOCKER"
855 >set-image-blocker</TT
858 >. You have the choice of a checkerboard pattern, a transparent 1x1 GIF
862 >), or a redirect to a custom image of your choice.
863 Note that this choice only has effect for images which are blocked as images, i.e.
864 whose URLs match both a <TT
867 HREF="../user-manual/actions-file.html#HANDLE-AS-IMAGE"
881 HREF="../user-manual/actions-file.html#BLOCK"
887 > If you want to see nothing, then change the <A
888 HREF="../user-manual/actions-file.html#SET-IMAGE-BLOCKER"
892 >set-image-blocker</TT
898 >. This can be done by editing the
902 > file, or through the <A
903 HREF="http://config.privoxy.org/show-status"
905 >web-based actions file editor</A
915 >3.13. Why would anybody want to see a checkerboard pattern?</H3
918 HREF="general.html#WHATSANAD"
919 >telling which image is an ad and which
921 >, is an educated guess. While we hope that the standard configuration
922 is rather smart, it will make occasional mistakes. The checkerboard image is visually
923 decent, but it shows you that and where images were blocked, which can be very
924 helpful in case some navigation aid or otherwise innocent image was
925 erroneously blocked. It is recommended for new users so they can
929 > what is happening. Some people might also enjoy seeing how
930 many banners they <SPAN
945 >3.14. I see some images being replaced by a text
946 instead of the checkerboard image. Why and how do I get rid of this?</H3
948 > This happens when the banners are not embedded in the HTML code of the
949 page itself, but in separate HTML (sub)documents that are loaded into (i)frames
950 or (i)layers, and these external HTML documents are blocked. Being non-images
951 they get replaced by a substitute HTML page rather than a substitute image,
952 which wouldn't work out technically, since the browser expects and accepts
953 only HTML when it has requested an HTML document. </P
955 > The substitute page adapts to the available space and shows itself as a
956 miniature two-liner if loaded into small frames, or full-blown with a
957 large red "BLOCKED" banner if space allows.</P
959 > If you prefer the banners to be blocked by images, you must see to it that
960 the HTML documents in which they are embedded are not blocked. Clicking
964 > link offered in the substitute page will show
965 you which rule blocked the page. After changing the rule and un-blocking
966 the HTML documents, the browser will try to load the actual banner images
967 and the usual image blocking will (hopefully!) kick in.</P
976 >3.15. Can Privoxy run as a service
979 > Yes. Version 3.0.5 introduces full <SPAN
983 functionality. See <A
984 HREF="../user-manual/installation.html#installation-pack-win"
990 > for details on how to install and configure
996 > Earlier 3.x versions could run as a system service using <B
1000 See the discussion at <A
1001 HREF="http://sourceforge.net/tracker/?func=detail&atid=361118&aid=485617&group_id=11118"
1003 >http://sourceforge.net/tracker/?func=detail&atid=361118&aid=485617&group_id=11118</A
1005 for details, and a sample configuration.</P
1014 >3.16. How can I make Privoxy work with other
1015 proxies like Squid or Tor?</H3
1017 > This can be done and is often useful to combine the benefits of
1021 > with those of a another proxy.
1023 HREF="../user-manual/config.html#FORWARDING"
1025 >forwarding chapter</A
1028 HREF="../user-manual/index.html"
1032 describes how to do this, and the <A
1033 HREF="misc.html#TOR"
1034 > How do I use Privoxy together with
1045 >3.17. Can I just set Privoxy to use port 80
1046 and thus avoid individual browser configuration?</H3
1048 > No, its more complicated than that. This only works with special kinds
1049 of proxies known as <SPAN
1051 >"transparent"</SPAN
1052 > proxies (see below).</P
1061 >3.18. Can Privoxy run as a <SPAN
1063 >"transparent"</SPAN
1069 > currently does not have this ability,
1070 though it may be added in a future release. Transparent proxies require
1071 special handling of the request headers beyond what
1075 > is now capable of.</P
1080 > behind another proxy that has
1081 this ability should work though.
1083 HREF="../user-manual/config.html#FORWARDING"
1085 >forwarding chapter</A
1088 HREF="../user-manual/index.html"
1092 a transparent proxy to be used for chaining we recommend Transproxy
1094 HREF="http://transproxy.sourceforge.net/"
1096 >http://transproxy.sourceforge.net/</A
1106 >3.19. How can I configure Privoxy for use with Outlook
1111 >Outlook Express</SPAN
1114 >Internet Explorer</SPAN
1116 components to both render HTML, and fetch any HTTP requests that may be embedded in an HTML email.
1117 So however you have <SPAN
1120 > configured to work
1121 with IE, this configuration should automatically be shared.</P
1130 >3.20. How can I have separate rules just for HTML mail?</H3
1132 > The short answer is, you can't. <SPAN
1136 of knowing which particular application makes a request, so there is no way to
1137 distinguish between web pages and HTML mail.
1141 > just blindly proxies all requests. In the
1144 >Outlook Express</SPAN
1145 > (see above), OE uses
1146 IE anyway, and there is no way for <SPAN
1150 be able to distinguish between them (nor could any other proxy type application for
1153 > For a good discussion of some of the issues involved (including privacy and
1154 security issues), see
1156 HREF="http://sourceforge.net/tracker/?func=detail&atid=211118&aid=629518&group_id=11118"
1158 >http://sourceforge.net/tracker/?func=detail&atid=211118&aid=629518&group_id=11118</A
1166 NAME="SNEAKY-COOKIES"
1168 >3.21. I sometimes notice cookies sneaking through. How?</H3
1171 HREF="http://en.wikipedia.org/wiki/Browser_cookie"
1175 set in several ways. The classic method is via the
1179 > HTTP header. This is straightforward, and an
1180 easy one to manipulate, such as the <SPAN
1185 HREF="../user-manual/actions-file.html#SESSION-COOKIES-ONLY"
1187 >session-cookies-only</A
1189 There is also the possibility of using
1191 HREF="http://en.wikipedia.org/wiki/Javascript"
1200 >content-cookies</TT
1202 is trickier because the syntax can vary widely, and thus requires a certain
1203 amount of guesswork. It is not realistic to catch all of these short of
1204 disabling Javascript, which would break many sites. And lastly, if the
1205 cookies are embedded in a HTTPS/SSL secure session via Javascript, they are beyond
1214 > can help manage cookies in general, can help minimize
1215 the loss of privacy posed by cookies, but can't realistically stop all
1225 >3.22. Are all cookies bad? Why?</H3
1227 > No, in fact there are many beneficial uses of
1229 HREF="http://en.wikipedia.org/wiki/Browser_cookie"
1232 >. Cookies are just a
1233 method that browsers can use to store data between pages, or between browser
1234 sessions. Sometimes there is a good reason for this, and the user's life is a
1235 bit easier as a result. But there is a long history of some websites taking
1236 advantage of this layer of trust, and using the data they glean from you and
1237 your browsing habits for their own purposes, and maybe to your potential
1238 detriment. Such sites are using you and storing their data on your system.
1239 That is why the security conscious watch from whom those cookies come, and why
1250 HREF="http://en.wikipedia.org/wiki/Browser_cookie"
1261 NAME="ALLOW-COOKIES"
1263 >3.23. How can I allow permanent cookies for my trusted sites?</H3
1265 > There are several actions that relate to cookies. The default behavior is to
1268 >"session cookies"</SPAN
1269 >, which means the cookies only last
1270 for the current browser session. This eliminates most kinds of abuse related
1271 to cookies. But there may be cases where we want cookies to last.</P
1273 > To disable all cookie actions, so that cookies are allowed unrestricted,
1274 both in and out, for <TT
1287 > { -crunch-incoming-cookies -crunch-outgoing-cookies -session-cookies-only -filter{content-cookies} }
1294 > Place the above in <TT
1297 >. Note some of these may
1298 be off by default anyway, so this might be redundant, but there is no harm
1299 being explicit in what you want to happen. <TT
1303 includes an alias for this situation, called
1306 >allow-all-cookies</TT
1316 >3.24. Can I have separate configurations for different users?</H3
1318 > Each instance of <SPAN
1322 configuration, including such attributes as the TCP port that it listens on.
1323 What you can do is run multiple instances of <SPAN
1330 > and configuration path, and then
1331 each of these can have their own configurations. Think of it as per-port
1335 Simple enough for a few users, but for large installations, consider having
1336 groups of users that might share like configurations.</P
1345 >3.25. Can I set-up Privoxy as a whitelist of
1351 > Sure. There are a couple of things you can do for simple whitelisting.
1352 Here's one real easy one:</P
1361 > ############################################################
1363 ############################################################
1365 HREF="../user-manual/actions-file.html#BLOCK"
1369 / # Block *all* URLs
1371 ############################################################
1373 ############################################################
1375 HREF="../user-manual/actions-file.html#BLOCK"
1381 games.example.com</PRE
1386 > This allows access to only those three sites by first blocking all URLs, and
1387 then subsequently allowing three specific exceptions.</P
1389 > A more interesting approach is <SPAN
1396 > concept, which incorporates the notion of
1399 >"trusted referrers"</SPAN
1401 HREF="../user-manual/config.html#TRUSTFILE"
1403 >User Manual Trust</A
1407 > These are fairly simple approaches and are not completely foolproof. There
1408 are various other configuration options that should be disabled (described
1409 elsewhere here and in <A
1410 HREF="../user-manual/"
1414 so that users can't modify their own configuration and easily circumvent the
1424 >3.26. How can I turn off ad-blocking?</H3
1426 > Ad blocking is hard-coded into the default configuration files. It has been
1427 assumed that everyone using <SPAN
1430 > is interested in this feature. If you want
1431 to do without this, there are several approaches you can take: You can
1432 manually undo the many block rules in <TT
1436 even easier, just create your own <TT
1440 from scratch without the many ad blocking rules, and corresponding exceptions.
1441 Or lastly, if you are not concerned about the additional blocks that are
1442 done for privacy reasons, you can very easily over-ride
1449 > blocking with the following very simple rule in
1464 > # Unblock everybody, everywhere
1466 HREF="../user-manual/actions-file.html#BLOCK"
1470 / # UN-Block *all* URLs
1478 Or even a more comprehensive reversing of various ad related actions:</P
1488 > # Unblock everybody, everywhere, and turn off appropriate filtering, etc
1490 HREF="../user-manual/actions-file.html#BLOCK"
1495 HREF="../user-manual/actions-file.html#FILTER-BANNERS-BY-SIZE"
1497 >-filter{banners-by-size}</A
1500 HREF="../user-manual/actions-file.html#FILTER-BANNERS-BY-SIZE"
1502 >-filter{banners-by-link}</A
1509 / # UN-Block *all* URLs and allow ads
1519 > in this compound statement,
1524 HREF="../user-manual/actions-file.html#ALIASES"
1528 various pop-up blocking features.</P
1537 >3.27. How can I have custom template pages, like the
1546 > All the template pages are installed in a sub-directory appropriately named:
1550 >. These are specialized text files utilized
1554 > and can easily be modified using any text editor. Knowing something
1555 about HTML will of course be helpful. You cannot rename any of these files,
1556 or create completely new templates, that is not possible. But you can change
1557 the page content to whatever you like. Be forewarned that these files are
1558 subject to being overwritten during upgrades, so be sure to save any
1568 >3.28. How can I remove the <SPAN
1570 >"Go There Anyway"</SPAN
1580 > Editing the template page (see above) may dissuade some users, but this
1581 method is easily circumvented. Where you want this level of control, you should
1585 > from source, and enable various features that are
1586 available as compile-time options. You should use
1600 > ./configure --disable-toggle --disable-editor --disable-force
1607 > This will create an executable with hard-coded security features so that
1611 > does not allow easy bypassing of blocks or changing the current
1612 configuration. Some of these features can also by toggled on/off via options
1618 HREF="../user-manual/config.html#ACCESS-CONTROL"
1622 compiled-in compliance is a much better method of ensuring that a block is
1625 > Default builds of <SPAN
1628 > are typically built with these features
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