X-Git-Url: http://www.privoxy.org/gitweb/?p=privoxy.git;a=blobdiff_plain;f=doc%2Fwebserver%2Ffaq%2Fconfiguration.html;h=2c19d28e70e7028df09150415da31b14fdbe5e68;hp=ef878304669647f2cc78575efc77638f90423e2e;hb=6d810395712f0337682205c4ea304009c86c128f;hpb=18e25b02853818f5d1e34ce3c999f5e3a43f6b9d diff --git a/doc/webserver/faq/configuration.html b/doc/webserver/faq/configuration.html index ef878304..2c19d28e 100644 --- a/doc/webserver/faq/configuration.html +++ b/doc/webserver/faq/configuration.html @@ -1,1798 +1,1027 @@ - -Configuration
Privoxy Frequently Asked Questions
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3. Configuration

3.1. What exactly is an "actions" file?

Privoxy utilizes the concept of " actions" - that are used to manipulate and control web page data. - Actions files - are where these actions - that Privoxy could take while processing a certain - request, are configured. Typically, you would define a set of default actions - that apply globally to all URLs, then add exceptions to these defaults where needed. - There is a wide array of actions available that give the user a high degree - of control and flexibility on how to process each and every web page.

Actions can be defined on a URL pattern basis, i.e. - for single URLs, whole web sites, groups or parts thereof etc. Actions can also be - grouped together and then applied to requests matching one or more patterns. - There are many possible actions that might apply to any given site. As an example, - if you are blocking cookies - as one of your default actions, but need to accept cookies from a given site, - you would need to define an exception for this site in one of your actions - files, preferably in user.action.

3.2. The "actions" concept confuses me. Please list -some of these "actions".

For a comprehensive discussion of the actions concept, please refer - to the actions file - chapter in the User - Manual. It includes a list of all actions - and an actions - file tutorial to get you started.

3.3. How are actions files configured? What is the easiest -way to do this?

Actions files are just text files in a special syntax and can be edited - with a text editor. But probably the easiest way is to access - Privoxy's user interface with your web browser - at http://config.privoxy.org/ - (Shortcut: http://p.p/) and then select - "View & - change the current configuration" from the menu. Note - that this feature must be explicitly enabled in the main config file - (see enable-edit-actions).

3.4. There are several different "actions" files. What are -the differences?

Three actions files - are being included by the developers, to be used for - different purposes: These are - default.action, the "main" actions file - which is actively maintained by the Privoxy - developers and typically sets the default policies, user.action, where users are encouraged - to make their private customizations, and standard.action, - which is for internal Privoxy use only. - Please see the actions chapter - in the User Manual for a more - detailed explanation.

Earlier versions included three different versions of the - default.action file. The new scheme allows for - greater flexibility of local configuration, and for browser based - selection of pre-defined "aggressiveness" levels.

3.5. Where can I get updated Actions Files?

Based on your feedback and the continuing development, updates of - default.action will be - made available from time to time on the files section of - our project page. -

If you wish to receive an email notification whenever we release updates of - Privoxy or the actions file, subscribe - to our announce mailing list, ijbswa-announce@lists.sourceforge.net. -

3.6. Can I use my old config files?

The syntax and purpose of configuration files has remained roughly the - same throughout the 3.x series, but backwards compatibility is not guaranteed. - Also each release contains updated, "improved" versions and it is - therefore strongly recommended to install the newer configuration files - and merge back your modifications. -

3.7. Why is the configuration so complicated?

"Complicated" is in the eye of the beholder. Those that are - familiar with some of the underlying concepts, such as regular expression - syntax, take to it like a fish takes to water. Also, software that tries - hard to be "user friendly", often lacks sophistication and - flexibility. There is always that trade-off there between power vs. - easy-of-use. Furthermore, anyone is welcome to contribute ideas and - implementations to enhance Privoxy. -

3.8. How can I make my Yahoo/Hotmail/Gmail account work?

The default configuration shouldn't impact the usability of any of these services. - It may, however, make all cookies - temporary, so that your browser will forget your - login credentials in between browser sessions. If you would like not to have to log - in manually each time you access those websites, simply turn off all cookie handling - for them in the user.action file. An example for yahoo might - look like: -

+ +
# Allow all cookies for Yahoo login:
+
+
+  
+    
+    
+      Configuration
+    
+    
+    
+    
+    
+    
+    
+
+  
+  
+    
+    
+

+ 3. Configuration +

+
+

+ 3.1. What exactly is an "actions" file? +

+

+ Privoxy utilizes the concept of + " actions" that are used to manipulate and control + web page data. Actions files are where these actions that Privoxy + could take while processing a certain request, are configured. + Typically, you would define a set of default actions that apply + globally to all URLs, then add exceptions to these defaults where + needed. There is a wide array of actions available that give the + user a high degree of control and flexibility on how to process + each and every web page. +

+

+ Actions can be defined on a URL + pattern basis, i.e. for single URLs, whole web sites, groups or + parts thereof etc. Actions can also be grouped together and then + applied to requests matching one or more patterns. There are many + possible actions that might apply to any given site. As an example, + if you are blocking cookies as one of your default actions, but need to + accept cookies from a given site, you would need to define an + exception for this site in one of your actions files, preferably in + user.action. +

+
+
+

+ 3.2. The "actions" + concept confuses me. Please list some of these "actions". +

+

+ For a comprehensive discussion of the actions concept, please refer + to the actions file chapter in the User Manual. It + includes a list of all actions and an actions file tutorial to get you started. +

+
+
+

+ 3.3. How are actions files configured? What is the + easiest way to do this? +

+

+ Actions files are just text files in a special syntax and can be + edited with a text editor. But probably the easiest way is to + access Privoxy's user interface + with your web browser at http://config.privoxy.org/ (Shortcut: http://p.p/) and then select "View & change the current + configuration" from the menu. Note that this feature + must be explicitly enabled in the main config file (see enable-edit-actions). +

+
+
+

+ 3.4. There are several different "actions" files. What are the differences? +

+

+ Please have a look at the the actions + chapter in the User Manual for a detailed explanation. +

+
+
+

+ 3.5. Where can I get updated Actions + Files? +

+

+ Based on your feedback and the continuing development, updates of + default.action will be made available + from time to time on the files section of our project page. +

+

+ If you wish to receive an email notification whenever we release + updates of Privoxy or the actions + file, subscribe to our announce mailing list, + ijbswa-announce@lists.sourceforge.net. +

+
+
+

+ 3.6. Can I use my old config files? +

+

+ The syntax and purpose of configuration files has remained roughly + the same throughout the 3.x series, but backwards compatibility is + not guaranteed. Also each release contains updated, "improved" versions and it is therefore strongly + recommended to install the newer configuration files and merge back + your modifications. +

+
+
+

+ 3.7. Why is the configuration so + complicated? +

+

+ "Complicated" is in the eye of the + beholder. Those that are familiar with some of the underlying + concepts, such as regular expression syntax, take to it like a fish + takes to water. Also, software that tries hard to be "user friendly", often lacks sophistication and + flexibility. There is always that trade-off there between power vs. + easy-of-use. Furthermore, anyone is welcome to contribute ideas and + implementations to enhance Privoxy. +

+
+
+

+ 3.8. How can I make my Yahoo/Hotmail/Gmail account + work? +

+

+ The default configuration shouldn't impact the usability of any of + these services. It may, however, make all cookies temporary, so that your browser will forget your + login credentials in between browser sessions. If you would like + not to have to log in manually each time you access those websites, + simply turn off all cookie handling for them in the user.action file. An example for yahoo might look + like: +

+

+

+ + +
+
+# Allow all cookies for Yahoo login:
 #
-{ -crunch-incoming-cookies -crunch-outgoing-cookies -session-cookies-only }
-.login.yahoo.com
-

These kinds of sites are often quite complex and heavy with - Javascript and - thus "fragile". So if still a problem, - we have an alias just for such - sticky situations: -

+ +
# Gmail is a _fragile_ site:
+{ -crunch-incoming-cookies -crunch-outgoing-cookies -session-cookies-only }
+.login.yahoo.com
+
+
+ +

+ These kinds of sites are often quite complex and heavy with Javascript and thus "fragile". So if still a problem, we have an alias + just for such sticky situations: +

+

+

+ + +
+
+# Gmail is a _fragile_ site:
 #
-{ fragile }
+{ fragile }
  # Gmail is ...
- mail.google.com
-

Be sure to flush your browser's caches whenever making these kinds of - changes, just to make sure the changes "take". -

Make sure the domain, host and path are appropriate as well. Your browser can - tell you where you are specifically and you should use that information for - your configuration settings. Note that above it is not referenced as - gmail.com, which is a valid domain name. -

3.9. What's the difference between the -"Cautious", "Medium" and "Advanced" defaults?

Configuring Privoxy is not entirely trivial. To - help you get started, we provide you with three different default action - "profiles" in the web based actions file editor at http://config.privoxy.org/show-status. - See the User - Manual for a list of actions, and how the default - profiles are set. -

Where the defaults are likely to break some sites, exceptions for - known popular "problem" sites are included, but in - general, the more aggressive your default settings are, the more exceptions - you will have to make later. New users are best to start off in - "Cautious" setting. This is safest and will have the fewest - problems. See the User Manual - for a more detailed discussion.

It should be noted that the "Advanced" profile (formerly known - as the "Adventuresome" profile) is more - aggressive, and will make use of some of - Privoxy's advanced features. Use at your own risk!

3.10. Why can I change the configuration -with a browser? Does that not raise security issues?

It may seem strange that regular users can edit the config files with their - browsers, although the whole /etc/privoxy hierarchy - belongs to the user "privoxy", with only 644 permissions. -

When you use the browser-based editor, Privoxy - itself is writing to the config files. Because - Privoxy is running as the user "privoxy", - it can update its own config files. -

If you run Privoxy for multiple untrusted users (e.g. in - a LAN) or aren't entirely in control of your own browser, you will probably want - to make sure that the the web-based editor and remote toggle features are - "off" by setting "enable-edit-actions - 0" and "enable-remote-toggle - 0" in the main configuration file. -

As of Privoxy 3.0.7 these options are disabled by default. -

3.11. What is the default.filter file? What is a "filter"?

The default.filter - file is where filters as supplied by the developers are defined. - Filters are a special subset of actions that can be used to modify or - remove web page content or headers on the fly. Content filters can - be applied to anything in the page source, - header filters can be applied to either server or client headers. - Regular expressions are used to accomplish this.

There are a number of pre-defined filters to deal with common annoyances. The - filters are only defined here, to invoke them, you need to use the - filter - action in one of the actions files. Content filtering is automatically - disabled for inappropriate MIME types, but if you now better than Privoxy - what should or should not be filtered you can filter any content you like.

Filters should - not be confused with blocks, which - is a completely different action, and is more typically used to block ads and - unwanted sites.

If you are familiar with regular expressions, and HTML, you can look at - the provided default.filter with a text editor and define - your own filters. This is potentially a very powerful feature, but - requires some expertise in both regular expressions and HTML/HTTP. - You should - place any modifications to the default filters, or any new ones you create - in a separate file, such as user.filter, so they won't - be overwritten during upgrades. - The ability to define multiple filter files - in config is a new feature as of v. 3.0.5.

There is no GUI editor option for this part of the configuration, - but you can disable/enable the various pre-defined filters of the included - default.filter file with the web-based actions file editor. - Note that the custom actions editor must be explicitly enabled in - the main config file (see enable-edit-actions).

If you intend to develop your own filters, you might want to have a look at - Privoxy-Filter-Test.

3.12. How can I set up Privoxy to act as a proxy for my - LAN?

By default, Privoxy only responds to requests - from 127.0.0.1 (localhost). To have it act as a server for - a network, this needs to be changed in the main configuration file. Look for - the listen-address - option, which may be commented out with a "#" symbol. Make sure - it is uncommented, and assign it the address of the LAN gateway interface, - and port number to use. Assuming your LAN address is 192.168.1.1 and you - wish to run Privoxy on port 8118, this line - should look like:

  listen-address  192.168.1.1:8118

Save the file, and restart Privoxy. Configure - all browsers on the network then to use this address and port number.

Alternately, you can have Privoxy listen on - all available interfaces:

  listen-address    :8118

And then use Privoxy's - permit-access - feature to limit connections. A firewall in this situation is recommended - as well.

The above steps should be the same for any TCP network, regardless of - operating system.

If you run Privoxy on a LAN with untrusted users, - we recommend that you double-check the access control and security - options!

3.13. Instead of ads, now I get a checkerboard pattern. I don't want to see anything.

The replacement for blocked images can be controlled with the set-image-blocker - action. You have the choice of a checkerboard pattern, a transparent 1x1 GIF - image (aka "blank"), or a redirect to a custom image of your choice. - Note that this choice only has effect for images which are blocked as images, i.e. - whose URLs match both a handle-as-image - and block action.

If you want to see nothing, then change the set-image-blocker - action to "blank". This can be done by editing the - user.action file, or through the web-based actions file editor.

3.14. Why would anybody want to see a checkerboard pattern?

Remember that telling which image is an ad and which - isn't, is an educated guess. While we hope that the standard configuration - is rather smart, it will make occasional mistakes. The checkerboard image is visually - decent, and it shows you where images have been blocked, which can be very - helpful in case some navigation aid or otherwise innocent image was - erroneously blocked. It is recommended for new users so they can - "see" what is happening. Some people might also enjoy seeing how - many banners they don't have to see.

3.15. I see some images being replaced with text -instead of the checkerboard image. Why and how do I get rid of this?

This happens when the banners are not embedded in the HTML code of the - page itself, but in separate HTML (sub)documents that are loaded into (i)frames - or (i)layers, and these external HTML documents are blocked. Being non-images - they get replaced by a substitute HTML page rather than a substitute image, - which wouldn't work out technically, since the browser expects and accepts - only HTML when it has requested an HTML document.

The substitute page adapts to the available space and shows itself as a - miniature two-liner if loaded into small frames, or full-blown with a - large red "BLOCKED" banner if space allows.

If you prefer the banners to be blocked by images, you must see to it that - the HTML documents in which they are embedded are not blocked. Clicking - the "See why" link offered in the substitute page will show - you which rule blocked the page. After changing the rule and un-blocking - the HTML documents, the browser will try to load the actual banner images - and the usual image blocking will (hopefully!) kick in.

3.16. Can Privoxy run as a service -on Win2K/NT/XP?

Yes. Version 3.0.5 introduces full Windows service - functionality. See the User Manual for details on how to install and configure - Privoxy as a service.

Earlier 3.x versions could run as a system service using srvany.exe. - See the discussion at http://sourceforge.net/tracker/?func=detail&atid=361118&aid=485617&group_id=11118, - for details, and a sample configuration.

3.17. How can I make Privoxy work with other -proxies like Squid or Tor?

This can be done and is often useful to combine the benefits of - Privoxy with those of a another proxy. - See the forwarding chapter - in the User Manual which - describes how to do this, and the How do I use Privoxy together with - Tor section below.

3.18. Can I just set Privoxy to use port 80 -and thus avoid individual browser configuration?

No, its more complicated than that. This only works with special kinds - of proxies known as "intercepting" proxies (see below).

3.19. Can Privoxy run as a "transparent" proxy?

The whole idea of Privoxy is to modify client requests - and server responses in all sorts of ways and therefore - it's not a transparent proxy as described in - RFC 2616.

However, some people say "transparent proxy" when they - mean "intercepting proxy". If you are one of them, - please read the next entry.

3.20. Can Privoxy run as a "intercepting" proxy?

Privoxy can't intercept traffic itself, - but it can handle requests that where intercepted and redirected - with a packet filter (like PF or - iptables), as long as the Host - header is present. -

As the Host header is required by HTTP/1.1 and as most - web sites rely on it anyway, this limitation shouldn't be a problem.

Please refer to your packet filter's documentation to learn how to - intercept and redirect traffic into Privoxy. - Afterward you just have to configure Privoxy to - accept - intercepted requests.

3.21. How can I configure Privoxy for use with Outlook - Express?

Outlook Express uses Internet Explorer - components to both render HTML, and fetch any HTTP requests that may be embedded in an HTML email. - So however you have Privoxy configured to work - with IE, this configuration should automatically be shared.

3.22. How can I have separate rules just for HTML mail?

The short answer is, you can't. Privoxy has no way - of knowing which particular application makes a request, so there is no way to - distinguish between web pages and HTML mail. - Privoxy just blindly proxies all requests. In the - case of Outlook Express (see above), OE uses - IE anyway, and there is no way for Privoxy to ever - be able to distinguish between them (nor could any other proxy type application for - that matter).

For a good discussion of some of the issues involved (including privacy and - security issues), see - http://sourceforge.net/tracker/?func=detail&atid=211118&aid=629518&group_id=11118.

3.23. I sometimes notice cookies sneaking through. How?

Cookies can be - set in several ways. The classic method is via the - Set-Cookie HTTP header. This is straightforward, and an - easy one to manipulate, such as the Privoxy concept of - session-cookies-only. - There is also the possibility of using - Javascript to - set cookies (Privoxy calls these content-cookies). This - is trickier because the syntax can vary widely, and thus requires a certain - amount of guesswork. It is not realistic to catch all of these short of - disabling Javascript, which would break many sites. And lastly, if the - cookies are embedded in a HTTPS/SSL secure session via Javascript, they are beyond - Privoxy's reach.

All in all, Privoxy can help manage cookies in general, can help minimize - the loss of privacy posed by cookies, but can't realistically stop all - cookies.

3.24. Are all cookies bad? Why?

No, in fact there are many beneficial uses of - cookies. Cookies are just a - method that browsers can use to store data between pages, or between browser - sessions. Sometimes there is a good reason for this, and the user's life is a - bit easier as a result. But there is a long history of some websites taking - advantage of this layer of trust, and using the data they glean from you and - your browsing habits for their own purposes, and maybe to your potential - detriment. Such sites are using you and storing their data on your system. - That is why the privacy conscious watch from whom those cookies come, and why - they really need to be there.

See the - Wikipedia cookie - definition for more.

3.25. How can I allow permanent cookies for my trusted sites?

There are several actions that relate to cookies. The default behavior is to - allow only "session cookies", which means the cookies only last - for the current browser session. This eliminates most kinds of abuse related - to cookies. But there may be cases where you want cookies to last.

To disable all cookie actions, so that cookies are allowed unrestricted, - both in and out, for example.com:

 { -crunch-incoming-cookies -crunch-outgoing-cookies -session-cookies-only -filter{content-cookies} }
-  .example.com

Place the above in user.action. Note that some of these may - be off by default anyway, so this might be redundant, but there is no harm - being explicit in what you want to happen. user.action - includes an alias for this situation, called - allow-all-cookies.

3.26. Can I have separate configurations for different users?

Each instance of Privoxy has its own - configuration, including such attributes as the TCP port that it listens on. - What you can do is run multiple instances of Privoxy, each with - a unique - listen-address - configuration setting, and configuration path, and then - each of these can have their own configurations. Think of it as per-port - configuration.

- Simple enough for a few users, but for large installations, consider having - groups of users that might share like configurations.

3.27. Can I set-up Privoxy as a whitelist of -"good" sites?

Sure. There are a couple of things you can do for simple white-listing. - Here's one real easy one:

+ +
 ############################################################
+ mail.google.com
+
+
+ +

+ Be sure to flush your browser's caches whenever making these kinds + of changes, just to make sure the changes "take". +

+

+ Make sure the domain, host and path are appropriate as well. Your + browser can tell you where you are specifically and you should use + that information for your configuration settings. Note that above + it is not referenced as gmail.com, which + is a valid domain name. +

+
+
+

+ 3.9. What's the difference between the "Cautious", "Medium" and "Advanced" + defaults? +

+

+ Configuring Privoxy is not + entirely trivial. To help you get started, we provide you with + three different default action "profiles" in the web based actions file editor at + http://config.privoxy.org/show-status. See the User Manual for a list of actions, and how the + default profiles are set. +

+

+ Where the defaults are likely to break some sites, exceptions for + known popular "problem" sites are + included, but in general, the more aggressive your default settings + are, the more exceptions you will have to make later. New users are + best to start off in "Cautious" setting. + This is safest and will have the fewest problems. See the User + Manual for a more detailed discussion. +

+

+ It should be noted that the "Advanced" + profile (formerly known as the "Adventuresome" profile) is more aggressive, and + will make use of some of Privoxy's + advanced features. Use at your own risk! +

+
+
+

+ 3.10. Why can I change the configuration + with a browser? Does that not raise security issues? +

+

+ It may seem strange that regular users can edit the config files + with their browsers, although the whole /etc/privoxy hierarchy belongs to the user "privoxy", with only 644 permissions. +

+

+ When you use the browser-based editor, Privoxy itself is writing to the config files. + Because Privoxy is running as the + user "privoxy", it can update its own + config files. +

+

+ If you run Privoxy for multiple + untrusted users (e.g. in a LAN) or aren't entirely in control of + your own browser, you will probably want to make sure that the + web-based editor and remote toggle features are "off" by setting "enable-edit-actions 0" and "enable-remote-toggle 0" in the main configuration + file. +

+

+ As of Privoxy 3.0.7 these options + are disabled by default. +

+
+
+

+ 3.11. What is the default.filter file? What is a "filter"? +

+

+ The default.filter file is where filters as supplied by + the developers are defined. Filters are a special subset of actions + that can be used to modify or remove web page content or headers on + the fly. Content filters can be applied to anything in the page + source, header filters can be applied to either server or client + headers. Regular expressions are used to accomplish this. +

+

+ There are a number of pre-defined filters to deal with common + annoyances. The filters are only defined here, to invoke them, you + need to use the filter action in one of + the actions files. Content filtering is automatically disabled for + inappropriate MIME types, but if you know better than Privoxy what + should or should not be filtered you can filter any content you + like. +

+

+ Filters should not be confused with blocks, which is a completely different action, + and is more typically used to block ads and unwanted sites. +

+

+ If you are familiar with regular expressions, and HTML, you can + look at the provided default.filter with + a text editor and define your own filters. This is potentially a + very powerful feature, but requires some expertise in both regular + expressions and HTML/HTTP. You should place any modifications to + the default filters, or any new ones you create in a separate file, + such as user.filter, so they won't be + overwritten during upgrades. The ability to define multiple filter + files in config is a new feature as of v. + 3.0.5. +

+

+ There is no GUI editor option for this part of the configuration, + but you can disable/enable the various pre-defined filters of the + included default.filter file with the web-based actions file editor. Note that the custom + actions editor must be explicitly enabled in the main config file + (see enable-edit-actions). +

+

+ If you intend to develop your own filters, you might want to have a + look at Privoxy-Filter-Test. +

+
+
+

+ 3.12. How can I set up Privoxy to act as a + proxy for my LAN? +

+

+ By default, Privoxy only responds + to requests from 127.0.0.1 (localhost). To + have it act as a server for a network, this needs to be changed in + the main + configuration file. Look for the listen-address option, which may be commented out + with a "#" symbol. Make sure it is + uncommented, and assign it the address of the LAN gateway + interface, and port number to use. Assuming your LAN address is + 192.168.1.1 and you wish to run Privoxy on port 8118, this line should look + like: +

+

+

+ + + + +
+
+  listen-address  192.168.1.1:8118
+
+
+ +

+ Save the file, and restart Privoxy. Configure all browsers on the network + then to use this address and port number. +

+

+ Alternately, you can have Privoxy + listen on all available interfaces: +

+

+

+ + + + +
+
+  listen-address    :8118
+
+
+ +

+ And then use Privoxy's permit-access feature to limit connections. A firewall + in this situation is recommended as well. +

+

+ The above steps should be the same for any TCP network, regardless + of operating system. +

+

+ If you run Privoxy on a LAN with + untrusted users, we recommend that you double-check the access + control and security options! +

+
+
+

+ 3.13. Instead of ads, now I get a checkerboard + pattern. I don't want to see anything. +

+

+ The replacement for blocked images can be controlled with the set-image-blocker action. You + have the choice of a checkerboard pattern, a transparent 1x1 GIF + image (aka "blank"), or a redirect to a + custom image of your choice. Note that this choice only has effect + for images which are blocked as images, i.e. whose URLs match both + a handle-as-image and block action. +

+

+ If you want to see nothing, then change the set-image-blocker action to + "blank". This can be done by editing the + user.action file, or through the web-based + actions file editor. +

+
+
+

+ 3.14. Why would anybody want to see a checkerboard + pattern? +

+

+ Remember that telling which image + is an ad and which isn't, is an educated guess. While we hope + that the standard configuration is rather smart, it will make + occasional mistakes. The checkerboard image is visually decent, and + it shows you where images have been blocked, which can be very + helpful in case some navigation aid or otherwise innocent image was + erroneously blocked. It is recommended for new users so they can + "see" what is happening. Some people + might also enjoy seeing how many banners they don't have to see. +

+
+
+

+ 3.15. I see some images being replaced with text + instead of the checkerboard image. Why and how do I get rid of + this? +

+

+ This happens when the banners are not embedded in the HTML code of + the page itself, but in separate HTML (sub)documents that are + loaded into (i)frames or (i)layers, and these external HTML + documents are blocked. Being non-images they get replaced by a + substitute HTML page rather than a substitute image, which wouldn't + work out technically, since the browser expects and accepts only + HTML when it has requested an HTML document. +

+

+ The substitute page adapts to the available space and shows itself + as a miniature two-liner if loaded into small frames, or full-blown + with a large red "BLOCKED" banner if space allows. +

+

+ If you prefer the banners to be blocked by images, you must see to + it that the HTML documents in which they are embedded are not + blocked. Clicking the "See why" link + offered in the substitute page will show you which rule blocked the + page. After changing the rule and un-blocking the HTML documents, + the browser will try to load the actual banner images and the usual + image blocking will (hopefully!) kick in. +

+
+
+

+ 3.16. Can Privoxy run as a service on + Win2K/NT/XP? +

+

+ Yes. Version 3.0.5 introduces full Windows service functionality. See the User Manual for details on + how to install and configure Privoxy as a service. +

+

+ Earlier 3.x versions could run as a system service using srvany.exe. See the discussion at http://sourceforge.net/tracker/?func=detail&atid=361118&aid=485617&group_id=11118, + for details, and a sample configuration. +

+
+
+

+ 3.17. How can I make Privoxy work with other + proxies? +

+

+ This can be done and is often useful to combine the benefits of + Privoxy with those of a another + proxy, for example to cache content. See the forwarding + chapter in the User Manual which describes how to do this. If you + intend to use Privoxy with Tor, please also have a look at How do I use Privoxy together with Tor. +

+
+
+

+ 3.18. Can I just set Privoxy to use port 80 and + thus avoid individual browser configuration? +

+

+ No, its more complicated than that. This only works with special + kinds of proxies known as "intercepting" + proxies (see below). +

+
+
+

+ 3.19. Can Privoxy run as a "transparent" proxy? +

+

+ The whole idea of Privoxy is to modify client requests and server + responses in all sorts of ways and therefore it's not a transparent + proxy as described in RFC 2616. +

+

+ However, some people say "transparent + proxy" when they mean "intercepting + proxy". If you are one of them, please read the next entry. +

+
+
+

+ 3.20. Can Privoxy run as a "intercepting" proxy? +

+

+ Privoxy can't intercept traffic + itself, but it can handle requests that where intercepted and + redirected with a packet filter (like PF or iptables), as long as the Host header is present. +

+

+ As the Host header is required by HTTP/1.1 + and as most web sites rely on it anyway, this limitation shouldn't + be a problem. +

+

+ Please refer to your packet filter's documentation to learn how to + intercept and redirect traffic into Privoxy. Afterward you just have to configure + Privoxy to accept intercepted requests. +

+
+
+

+ 3.21. How can I configure Privoxy for use with + Outlook? +

+

+ Versions of Outlook prior to + Office 2007, use Internet Explorer + components to both render HTML, and fetch any HTTP requests that + may be embedded in an HTML email. So however you have Privoxy configured to work with IE, this + configuration should automatically be shared, at least with older + version of Internet Explorer. +

+

+ Starting with Office 2007, Microsoft is instead using the MS-Word + rendering engine with Outlook. It is unknown whether this can be + configured to use a proxy. +

+
+
+

+ 3.22. How can I have separate rules just for + HTML mail? +

+

+ The short answer is, you can't. Privoxy has no way of knowing which particular + application makes a request, so there is no way to distinguish + between web pages and HTML mail. Privoxy just blindly proxies all requests. In + the case of Outlook Express (see + above), OE uses IE anyway, and there is no way for Privoxy to ever be able to distinguish between + them (nor could any other proxy type application for that matter). +

+

+ For a good discussion of some of the issues involved (including + privacy and security issues), see http://sourceforge.net/tracker/?func=detail&atid=211118&aid=629518&group_id=11118. +

+
+
+

+ 3.23. I sometimes notice cookies sneaking + through. How? +

+

+ Cookies can be set in several ways. The classic method + is via the Set-Cookie HTTP header. This is + straightforward, and an easy one to manipulate, such as the Privoxy concept of session-cookies-only. There is also the possibility of + using Javascript to set cookies (Privoxy calls these content-cookies). This is trickier because the + syntax can vary widely, and thus requires a certain amount of + guesswork. It is not realistic to catch all of these short of + disabling Javascript, which would break many sites. And lastly, if + the cookies are embedded in a HTTPS/SSL secure session via + Javascript, they are beyond Privoxy's reach. +

+

+ All in all, Privoxy can help + manage cookies in general, can help minimize the loss of privacy + posed by cookies, but can't realistically stop all cookies. +

+
+
+

+ 3.24. Are all cookies bad? Why? +

+

+ No, in fact there are many beneficial uses of cookies. Cookies are just a method that browsers can use + to store data between pages, or between browser sessions. Sometimes + there is a good reason for this, and the user's life is a bit + easier as a result. But there is a long history of some websites + taking advantage of this layer of trust, and using the data they + glean from you and your browsing habits for their own purposes, and + maybe to your potential detriment. Such sites are using you and + storing their data on your system. That is why the privacy + conscious watch from whom those cookies come, and why they really + need to be + there. +

+

+ See the Wikipedia cookie definition for more. +

+
+
+

+ 3.25. How can I allow permanent cookies for + my trusted sites? +

+

+ There are several actions that relate to cookies. The default + behavior is to allow only "session + cookies", which means the cookies only last for the current + browser session. This eliminates most kinds of abuse related to + cookies. But there may be cases where you want cookies to last. +

+

+ To disable all cookie actions, so that cookies are allowed + unrestricted, both in and out, for example.com: +

+

+

+ + + + +
+
+ { -crunch-incoming-cookies -crunch-outgoing-cookies -session-cookies-only -filter{content-cookies} }
+  .example.com
+
+
+ +

+ Place the above in user.action. Note that + some of these may be off by default anyway, so this might be + redundant, but there is no harm being explicit in what you want to + happen. user.action includes an alias for + this situation, called allow-all-cookies. +

+
+
+

+ 3.26. Can I have separate configurations for + different users? +

+

+ Each instance of Privoxy has its + own configuration, including such attributes as the TCP port that + it listens on. What you can do is run multiple instances of Privoxy, each with a unique listen-address configuration setting, and configuration + path, and then each of these can have their own configurations. + Think of it as per-port configuration. +

+

+ Simple enough for a few users, but for large installations, + consider having groups of users that might share like + configurations. +

+
+
+

+ 3.27. Can I set-up Privoxy as a whitelist of + "good" sites? +

+

+ Sure. There are a couple of things you can do for simple + white-listing. Here's one real easy one: +

+ + +
+
+ ############################################################
  # Blacklist
  ############################################################
- { +block }
+ { +block }
  / # Block *all* URLs
- 
+
  ############################################################
  # Whitelist
  ############################################################
- { -block }
+ { -block }
   kids.example.com
   toys.example.com
-  games.example.com

This allows access to only those three sites by first blocking all URLs, and - then subsequently allowing three specific exceptions.

Another approach is Privoxy's - trustfile concept, which incorporates the notion of - "trusted referrers". See the Trust documentation - for details.

These are fairly simple approaches and are not completely foolproof. There - are various other configuration options that should be disabled (described - elsewhere here and in the User Manual) - so that users can't modify their own configuration and easily circumvent the - whitelist.

3.28. How can I turn off ad-blocking?

Ad blocking is achieved through a complex application of various Privoxy - actions. These - actions are deployed against simple images, banners, flash animations, - text pages, JavaScript, pop-ups and pop-unders, etc., so its not as simple as - just turning one or two actions off. The various actions that make up - Privoxy ad blocking are hard-coded into the default configuration files. It - has been assumed that everyone using Privoxy is interested in this - particular feature. -

If you want to do without this, there are several approaches you can take: - You can manually undo the many block rules in - default.action. Or even easier, just create your own - default.action file from scratch without the many ad - blocking rules, and corresponding exceptions. Or lastly, if you are not - concerned about the additional blocks that are done for privacy reasons, you - can very easily over-ride all blocking with the - following very simple rule in your user.action: -

 # Unblock everybody, everywhere
- { -block }
- / # UN-Block *all* URLs

- Or even a more comprehensive reversing of various ad related actions:

+ +
 # Unblock everybody, everywhere, and turn off appropriate filtering, etc
- { -block \
-  -filter{banners-by-size} \
-  -filter{banners-by-link} \
-  allow-popups \
+  games.example.com
+
+
+

+ This allows access to only those three sites by first blocking all + URLs, and then subsequently allowing three specific exceptions. +

+

+ Another approach is Privoxy's trustfile concept, which incorporates the + notion of "trusted referrers". See the + Trust + documentation for details. +

+

+ These are fairly simple approaches and are not completely + foolproof. There are various other configuration options that + should be disabled (described elsewhere here and in the User Manual) so that users + can't modify their own configuration and easily circumvent the + whitelist. +

+
+
+

+ 3.28. How can I turn off ad-blocking? +

+

+ Ad blocking is achieved through a complex application of various + Privoxy actions. These + actions are deployed against simple images, banners, flash + animations, text pages, JavaScript, pop-ups and pop-unders, etc., + so its not as simple as just turning one or two actions off. The + various actions that make up Privoxy ad blocking are hard-coded into the + default configuration files. It has been assumed that everyone + using Privoxy is interested in + this particular feature. +

+

+ If you want to do without this, there are several approaches you + can take: You can manually undo the many block rules in default.action. Or even easier, just create your + own default.action file from scratch + without the many ad blocking rules, and corresponding exceptions. + Or lastly, if you are not concerned about the additional blocks + that are done for privacy reasons, you can very easily over-ride + all blocking + with the following very simple rule in your user.action: +

+

+

+ + + + +
+
+ # Unblock everybody, everywhere
+ { -block }
+ / # UN-Block *all* URLs
+
+
+ +

+ Or even a more comprehensive reversing of various ad related + actions: +

+

+

+ + +
+
+ # Unblock everybody, everywhere, and turn off appropriate filtering, etc
+ { -block \
+  -filter{banners-by-size} \
+  -filter{banners-by-link} \
+  allow-popups \
  }
- / # UN-Block *all* URLs and allow ads

This last "action" in this compound statement, - allow-popups, is an alias that disables - various pop-up blocking features.

3.29. How can I have custom template pages, like the -BLOCKED page?

Privoxy "templates" are specialized text files utilized by - Privoxy for various purposes and can easily be modified using any text - editor. All the template pages are installed in a sub-directory appropriately - named: templates. Knowing something about HTML syntax - will of course be helpful.

Be forewarned that the default templates are subject to being overwritten - during upgrades. You can, however, create completely new templates, - place them in another directory and specify the alternate path in the main - config. For details, have a look at the templdir option.

3.30. How can I remove the "Go There Anyway" link from -the BLOCKED page?

There is more than one way to do it (although Perl is not involved).

Editing the BLOCKED template page (see above) may dissuade some users, but - this method is easily circumvented. Where you need this level of control, you - might want to build Privoxy from source, and disable various features that are - available as compile-time options. You should - configure the sources as follows:

 ./configure  --disable-toggle  --disable-editor  --disable-force

This will create an executable with hard-coded security features so that - Privoxy does not allow easy bypassing of blocked sites, or changing the - current configuration via any connected user's web browser.

Finally, all of these features can also be toggled on/off via options in - Privoxy's main config file which - means you don't have to recompile anything.


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Installation Miscellaneous
\ No newline at end of file + / # UN-Block *all* URLs and allow ads +
+
+ +

+ This last "action" in this compound + statement, allow-popups, is an alias + that disables various pop-up blocking features. +

+
+
+

+ 3.29. How can I have custom template pages, + like the BLOCKED page? +

+

+ Privoxy "templates" are specialized text files utilized by + Privoxy for various purposes and + can easily be modified using any text editor. All the template + pages are installed in a sub-directory appropriately named: templates. Knowing something about HTML + syntax will of course be helpful. +

+

+ Be forewarned that the default templates are subject to being + overwritten during upgrades. You can, however, create completely + new templates, place them in another directory and specify the + alternate path in the main config. For + details, have a look at the templdir + option. +

+
+
+

+ 3.30. How can I remove the "Go There Anyway" link from the BLOCKED page? +

+

+ There is more than one way to do it (although Perl is not + involved). +

+

+ Editing the BLOCKED template page (see above) may dissuade some + users, but this method is easily circumvented. Where you need this + level of control, you might want to build Privoxy from source, and disable various + features that are available as compile-time options. You should configure the sources as follows: +

+

+

+ + + + +
+
+ ./configure  --disable-toggle  --disable-editor  --disable-force
+
+
+ +

+ This will create an executable with hard-coded security features so + that Privoxy does not allow easy + bypassing of blocked sites, or changing the current configuration + via any connected user's web browser. +

+

+ Finally, all of these features can also be toggled on/off via + options in Privoxy's main config file which means you don't have to recompile + anything. +

+
+
+ + + +