Privoxy 3.0.10 User Manual
Prev		Next

8. Actions Files

The actions files are used to define what actions - Privoxy takes for which URLs, and thus determines - how ad images, cookies and various other aspects of HTTP content and - transactions are handled, and on which sites (or even parts thereof). - There are a number of such actions, with a wide range of functionality. - Each action does something a little different. - These actions give us a veritable arsenal of tools with which to exert - our control, preferences and independence. Actions can be combined so that - their effects are aggregated when applied against a given set of URLs.

There - are three action files included with Privoxy with - differing purposes: -

default.action - is the primary action file - that sets the initial values for all actions. It is intended to - provide a base level of functionality for - Privoxy's array of features. So it is - a set of broad rules that should work reasonably well as-is for most users. - This is the file that the developers are keeping updated, and making available to users. - The user's preferences as set in standard.action, - e.g. either Cautious (the default), - Medium, or Advanced (see - below). -
user.action - is intended to be for local site - preferences and exceptions. As an example, if your ISP or your bank - has specific requirements, and need special handling, this kind of - thing should go here. This file will not be upgraded. -

standard.action - is used only by the web based editor - at http://config.privoxy.org/edit-actions-list?f=default, - to set various pre-defined sets of rules for the default actions section - in default.action. -

Edit Set to Cautious Set to Medium Set to Advanced -

These have increasing levels of aggressiveness and have no - influence on your browsing unless you select them explicitly in the - editor. A default installation should be pre-set to - Cautious (versions prior to 3.0.5 were set to - Medium). New users should try this for a while before - adjusting the settings to more aggressive levels. The more aggressive - the settings, then the more likelihood there is of problems such as sites - not working as they should. -

The Edit button allows you to turn each - action on/off individually for fine-tuning. The Cautious - button changes the actions list to low/safe settings which will activate - ad blocking and a minimal set of Privoxy's features, and subsequently - there will be less of a chance for accidental problems. The - Medium button sets the list to a medium level of - other features and a low level set of privacy features. The - Advanced button sets the list to a high level of - ad blocking and medium level of privacy. See the chart below. The latter - three buttons over-ride any changes via with the - Edit button. More fine-tuning can be done in the - lower sections of this internal page. -

It is not recommend to edit the standard.action file - itself. -

The default profiles, and their associated actions, as pre-defined in - standard.action are: -

Table 1. Default Configurations

Feature	Cautious	Medium	Advanced
Ad-blocking Aggressiveness	medium	high	high
Ad-filtering by size	no	yes	yes
Ad-filtering by link	no	no	yes
Pop-up killing	blocks only	blocks only	blocks only
Privacy Features	low	medium	medium/high
Cookie handling	none	session-only	kill
Referer forging	no	yes	yes
GIF de-animation	no	yes	yes
Fast redirects	no	no	yes
HTML taming	no	no	yes
JavaScript taming	no	no	yes
Web-bug killing	no	yes	yes
Image tag reordering	no	yes	yes

The list of actions files to be used are defined in the main configuration - file, and are processed in the order they are defined (e.g. - default.action is typically processed before - user.action). The content of these can all be viewed and - edited from http://config.privoxy.org/show-status. - The over-riding principle when applying actions, is that the last action that - matches a given URL wins. The broadest, most general rules go first - (defined in default.action), - followed by any exceptions (typically also in - default.action), which are then followed lastly by any - local preferences (typically in user.action). - Generally, user.action has the last word. -

An actions file typically has multiple sections. If you want to use - "aliases" in an actions file, you have to place the (optional) - alias section at the top of that file. - Then comes the default set of rules which will apply universally to all - sites and pages (be very careful with using such a - universal set in user.action or any other actions file after - default.action, because it will override the result - from consulting any previous file). And then below that, - exceptions to the defined universal policies. You can regard - user.action as an appendix to default.action, - with the advantage that it is a separate file, which makes preserving your - personal settings across Privoxy upgrades easier.

- Actions can be used to block anything you want, including ads, banners, or - just some obnoxious URL whose content you would rather not see. Cookies can be accepted - or rejected, or accepted only during the current browser session (i.e. not - written to disk), content can be modified, some JavaScripts tamed, user-tracking - fooled, and much more. See below for a complete list - of actions.

8.1. Finding the Right Mix

Note that some actions, like cookie suppression - or script disabling, may render some sites unusable that rely on these - techniques to work properly. Finding the right mix of actions is not always easy and - certainly a matter of personal taste. And, things can always change, requiring - refinements in the configuration. In general, it can be said that the more - "aggressive" your default settings (in the top section of the - actions file) are, the more exceptions for "trusted" sites you - will have to make later. If, for example, you want to crunch all cookies per - default, you'll have to make exceptions from that rule for sites that you - regularly use and that require cookies for actually useful purposes, like maybe - your bank, favorite shop, or newspaper.

We have tried to provide you with reasonable rules to start from in the - distribution actions files. But there is no general rule of thumb on these - things. There just are too many variables, and sites are constantly changing. - Sooner or later you will want to change the rules (and read this chapter again :).

8.2. How to Edit

The easiest way to edit the actions files is with a browser by - using our browser-based editor, which can be reached from http://config.privoxy.org/show-status. - Note: the config file option enable-edit-actions must be enabled for - this to work. The editor allows both fine-grained control over every single - feature on a per-URL basis, and easy choosing from wholesale sets of defaults - like "Cautious", "Medium" or - "Advanced". Warning: the "Advanced" setting is more - aggressive, and will be more likely to cause problems for some sites. - Experienced users only! -

If you prefer plain text editing to GUIs, you can of course also directly edit the - the actions files with your favorite text editor. Look at - default.action which is richly commented with many - good examples.

8.3. How Actions are Applied to Requests

Actions files are divided into sections. There are special sections, - like the "alias" sections which will - be discussed later. For now let's concentrate on regular sections: They have a - heading line (often split up to multiple lines for readability) which consist - of a list of actions, separated by whitespace and enclosed in curly braces. - Below that, there is a list of URL and tag patterns, each on a separate line.

To determine which actions apply to a request, the URL of the request is - compared to all URL patterns in each "action file". - Every time it matches, the list of applicable actions for the request is - incrementally updated, using the heading of the section in which the - pattern is located. The same is done again for tags and tag patterns later on.

If multiple applying sections set the same action differently, - the last match wins. If not, the effects are aggregated. - E.g. a URL might match a regular section with a heading line of { - +handle-as-image }, - then later another one with just { - +block }, resulting - in both actions to apply. And there may well be - cases where you will want to combine actions together. Such a section then - might look like:

+ +
{ +handle-as-image +block{Banner ads.} } + + + + + Actions Files + + + + + + + + + + +
+ + + + + + + + + +
+ Privoxy 3.0.26 User Manual +
+ Prev + + + Next +
+
+
+
+
+ 8. Actions Files +
+
+ The actions files are used to define what actions Privoxy takes for which URLs, and thus + determines how ad images, cookies and various other aspects of HTTP + content and transactions are handled, and on which sites (or even + parts thereof). There are a number of such actions, with a wide range + of functionality. Each action does something a little different. + These actions give us a veritable arsenal of tools with which to + exert our control, preferences and independence. Actions can be + combined so that their effects are aggregated when applied against a + given set of URLs. +
+
+ There are three action files included with Privoxy with differing purposes: +
+
+
+
+
+
+ match-all.action - is used to define + which "actions" relating to + banner-blocking, images, pop-ups, content modification, cookie + handling etc should be applied by default. It should be the first + actions file loaded +
+
+
+
+ default.action - defines many + exceptions (both positive and negative) from the default set of + actions that's configured in match-all.action. It is a set of rules that + should work reasonably well as-is for most users. This file is + only supposed to be edited by the developers. It should be the + second actions file loaded. +
+
+
+
+ user.action - is intended to be for + local site preferences and exceptions. As an example, if your ISP + or your bank has specific requirements, and need special + handling, this kind of thing should go here. This file will not + be upgraded. +
+
+
+
+ Edit Set + to Cautious Set to Medium + Set to Advanced +
+
+ These have increasing levels of aggressiveness and have no influence on your + browsing unless you select them explicitly in the + editor. A default installation should be pre-set to + Cautious. New users should try this for + a while before adjusting the settings to more aggressive levels. + The more aggressive the settings, then the more likelihood there + is of problems such as sites not working as they should. +
+
+ The Edit button allows you to turn + each action on/off individually for fine-tuning. The Cautious button changes the actions list to + low/safe settings which will activate ad blocking and a minimal + set of Privoxy's features, and + subsequently there will be less of a chance for accidental + problems. The Medium button sets + the list to a medium level of other features and a low level set + of privacy features. The Advanced + button sets the list to a high level of ad blocking and medium + level of privacy. See the chart below. The latter three buttons + over-ride any changes via with the Edit button. More fine-tuning can be done in + the lower sections of this internal page. +
+
+ While the actions file editor allows to enable these settings in + all actions files, they are only supposed to be enabled in the + first one to make sure you don't unintentionally overrule earlier + rules. +
+
+ The default profiles, and their associated actions, as + pre-defined in default.action are: +
+
+
+
+ +
+ Table 1. Default Configurations +
+ + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + +

+ Feature + + Cautious + + Medium + + Advanced +
+ Ad-blocking Aggressiveness + + medium + + high + + high +
+ Ad-filtering by size + + no + + yes + + yes +
+ Ad-filtering by link + + no + + no + + yes +
+ Pop-up killing + + blocks only + + blocks only + + blocks only +
+ Privacy Features + + low + + medium + + medium/high +
+ Cookie handling + + none + + session-only + + kill +
+ Referer forging + + no + + yes + + yes +
+ GIF de-animation + + no + + yes + + yes +
+ Fast redirects + + no + + no + + yes +
+ HTML taming + + no + + no + + yes +
+ JavaScript taming + + no + + no + + yes +
+ Web-bug killing + + no + + yes + + yes +
+ Image tag reordering + + no + + yes + + yes +
+
+
+
+ +
+ The list of actions files to be used are defined in the main + configuration file, and are processed in the order they are defined + (e.g. default.action is typically processed + before user.action). The content of these + can all be viewed and edited from http://config.privoxy.org/show-status. The over-riding + principle when applying actions, is that the last action that matches + a given URL wins. The broadest, most general rules go first (defined + in default.action), followed by any + exceptions (typically also in default.action), which are then followed lastly by + any local preferences (typically in user.action). + Generally, user.action has the last word. +
+
+ An actions file typically has multiple sections. If you want to use + "aliases" in an actions file, you have to + place the (optional) alias + section at the top of that file. Then comes the default set of + rules which will apply universally to all sites and pages (be very careful with + using such a universal set in user.action + or any other actions file after default.action, because it will override the result + from consulting any previous file). And then below that, exceptions + to the defined universal policies. You can regard user.action as an appendix to default.action, with the advantage that it is a + separate file, which makes preserving your personal settings across + Privoxy upgrades easier. +
+
+ Actions can be used to block anything you want, including ads, + banners, or just some obnoxious URL whose content you would rather + not see. Cookies can be accepted or rejected, or accepted only during + the current browser session (i.e. not written to disk), content can + be modified, some JavaScripts tamed, user-tracking fooled, and much + more. See below for a complete + list of actions. +
+
+
+ 8.1. Finding the Right Mix +
+
+ Note that some actions, + like cookie suppression or script disabling, may render some sites + unusable that rely on these techniques to work properly. Finding + the right mix of actions is not always easy and certainly a matter + of personal taste. And, things can always change, requiring + refinements in the configuration. In general, it can be said that + the more "aggressive" your default + settings (in the top section of the actions file) are, the more + exceptions for "trusted" sites you will + have to make later. If, for example, you want to crunch all cookies + per default, you'll have to make exceptions from that rule for + sites that you regularly use and that require cookies for actually + useful purposes, like maybe your bank, favorite shop, or newspaper. +
+
+ We have tried to provide you with reasonable rules to start from in + the distribution actions files. But there is no general rule of + thumb on these things. There just are too many variables, and sites + are constantly changing. Sooner or later you will want to change + the rules (and read this chapter again :). +
+
+
+
+ 8.2. How to Edit +
+
+ The easiest way to edit the actions files is with a browser by + using our browser-based editor, which can be reached from http://config.privoxy.org/show-status. Note: the config + file option enable-edit-actions must be + enabled for this to work. The editor allows both fine-grained + control over every single feature on a per-URL basis, and easy + choosing from wholesale sets of defaults like "Cautious", "Medium" or + "Advanced". Warning: the "Advanced" setting is more aggressive, and will be + more likely to cause problems for some sites. Experienced users + only! +
+
+ If you prefer plain text editing to GUIs, you can of course also + directly edit the the actions files with your favorite text editor. + Look at default.action which is richly + commented with many good examples. +
+
+
+
+ 8.3. How Actions are Applied to + Requests +
+
+ Actions files are divided into sections. There are special + sections, like the "alias" sections which will + be discussed later. For now let's concentrate on regular sections: + They have a heading line (often split up to multiple lines for + readability) which consist of a list of actions, separated by + whitespace and enclosed in curly braces. Below that, there is a + list of URL and tag patterns, each on a separate line. +
+
+ To determine which actions apply to a request, the URL of the + request is compared to all URL patterns in each "action file". Every time it matches, the list of + applicable actions for the request is incrementally updated, using + the heading of the section in which the pattern is located. The + same is done again for tags and tag patterns later on. +
+
+ If multiple applying sections set the same action differently, the + last match wins. If not, the effects are aggregated. E.g. a URL + might match a regular section with a heading line of { +handle-as-image }, + then later another one with just { +block }, resulting in both actions to + apply. And there may well be cases where you will want to combine + actions together. Such a section then might look like: +
+
+
+ + +
+
+ { +handle-as-image +block{Banner ads.} } # Block these as if they were images. Send no block page. banners.example.com media.example.com/.*banners - .example.com/images/ads/
-
You can trace this process for URL patterns and any given URL by visiting http://config.privoxy.org/show-url-info.
Examples and more detail on this is provided in the Appendix, Troubleshooting: Anatomy of an Action section.
8.4. Patterns
- As mentioned, Privoxy uses "patterns" - to determine what actions might apply to which sites and - pages your browser attempts to access. These "patterns" use wild - card type pattern matching to achieve a high degree of - flexibility. This allows one expression to be expanded and potentially match - against many similar patterns.
Generally, an URL pattern has the form - <domain>/<path>, where both the - <domain> and <path> are - optional. (This is why the special / pattern matches all - URLs). Note that the protocol portion of the URL pattern (e.g. - http://) should not be included in - the pattern. This is assumed already!
The pattern matching syntax is different for the domain and path parts of - the URL. The domain part uses a simple globbing type matching technique, - while the path part uses more flexible - "Regular - Expressions" (POSIX 1003.2).
www.example.com/
is a domain-only pattern and will match any request to www.example.com, - regardless of which document on that server is requested. So ALL pages in - this domain would be covered by the scope of this action. Note that a - simple example.com is different and would NOT match. -
www.example.com
means exactly the same. For domain-only patterns, the trailing / may - be omitted. -
www.example.com/index.html
matches all the documents on www.example.com - whose name starts with /index.html. -
www.example.com/index.html$
matches only the single document /index.html - on www.example.com. -
/index.html$
matches the document /index.html, regardless of the domain, - i.e. on any web server anywhere. -
index.html
matches nothing, since it would be interpreted as a domain name and - there is no top-level domain called .html. So its - a mistake. -
8.4.1. The Domain Pattern
The matching of the domain part offers some flexible options: if the - domain starts or ends with a dot, it becomes unanchored at that end. - For example:
.example.com
matches any domain with first-level domain com - and second-level domain example. - For example www.example.com, - example.com and foo.bar.baz.example.com. - Note that it wouldn't match if the second-level domain was another-example. -
www.
matches any domain that STARTS with - www. (It also matches the domain - www but most of the time that doesn't matter.) -
.example.
matches any domain that CONTAINS .example.. - And, by the way, also included would be any files or documents that exist - within that domain since no path limitations are specified. (Correctly - speaking: It matches any FQDN that contains example as - a domain.) This might be www.example.com, - news.example.de, or - www.example.net/cgi/testing.pl for instance. All these - cases are matched. -
Additionally, there are wild-cards that you can use in the domain names - themselves. These work similarly to shell globbing type wild-cards: - "*" represents zero or more arbitrary characters (this is - equivalent to the - "Regular - Expression" based syntax of ".*"), - "?" represents any single character (this is equivalent to the - regular expression syntax of a simple "."), and you can define - "character classes" in square brackets which is similar to - the same regular expression technique. All of this can be freely mixed:
ad*.example.com
matches "adserver.example.com", - "ads.example.com", etc but not "sfads.example.com" -
*ad*.example.com
matches all of the above, and then some. -
.?pix.com
matches www.ipix.com, - pictures.epix.com, a.b.c.d.e.upix.com etc. -
www[1-9a-ez].example.c*
matches www1.example.com, - www4.example.cc, wwwd.example.cy, - wwwz.example.com etc., but not - wwww.example.com. -
While flexible, this is not the sophistication of full regular expression based syntax.
8.4.2. The Path Pattern
Privoxy uses "modern" POSIX 1003.2 - "Regular - Expressions" for matching the path portion (after the slash), - and is thus more flexible.
There is an Appendix with a brief quick-start into regular - expressions, you also might want to have a look at your operating system's documentation - on regular expressions (try man re_format).
Note that the path pattern is automatically left-anchored at the "/", - i.e. it matches as if it would start with a "^" (regular expression speak - for the beginning of a line).
Please also note that matching in the path is CASE INSENSITIVE - by default, but you can switch to case sensitive at any point in the pattern by using the - "(?-i)" switch: www.example.com/(?-i)PaTtErN.* will match - only documents whose path starts with PaTtErN in - exactly this capitalization.
.example.com/.*
Is equivalent to just ".example.com", since any documents - within that domain are matched with or without the ".*" - regular expression. This is redundant -
.example.com/.*/index.html$
Will match any page in the domain of "example.com" that is - named "index.html", and that is part of some path. For - example, it matches "www.example.com/testing/index.html" but - NOT "www.example.com/index.html" because the regular - expression called for at least two "/'s", thus the path - requirement. It also would match - "www.example.com/testing/index_html", because of the - special meta-character ".". -
.example.com/(.*/)?index\.html$
This regular expression is conditional so it will match any page - named "index.html" regardless of path which in this case can - have one or more "/'s". And this one must contain exactly - ".html" (but does not have to end with that!). -
.example.com/(.*/)(ads|banners?|junk)
This regular expression will match any path of "example.com" - that contains any of the words "ads", "banner", - "banners" (because of the "?") or "junk". - The path does not have to end in these words, just contain them. -
.example.com/(.*/)(ads|banners?|junk)/.*\.(jpe?g|gif|png)$
This is very much the same as above, except now it must end in either - ".jpg", ".jpeg", ".gif" or ".png". So this - one is limited to common image formats. -
There are many, many good examples to be found in default.action, - and more tutorials below in Appendix on regular expressions.
8.4.3. The Tag Pattern
Tag patterns are used to change the applying actions based on the - request's tags. Tags can be created with either the - client-header-tagger - or the server-header-tagger action.
Tag patterns have to start with "TAG:", so Privoxy - can tell them apart from URL patterns. Everything after the colon - including white space, is interpreted as a regular expression with - path pattern syntax, except that tag patterns aren't left-anchored - automatically (Privoxy doesn't silently add a "^", - you have to do it yourself if you need it).
To match all requests that are tagged with "foo" - your pattern line should be "TAG:^foo$", - "TAG:foo" would work as well, but it would also - match requests whose tags contain "foo" somewhere. - "TAG: foo" wouldn't work as it requires white space.
Sections can contain URL and tag patterns at the same time, - but tag patterns are checked after the URL patterns and thus - always overrule them, even if they are located before the URL patterns.
Once a new tag is added, Privoxy checks right away if it's matched by one - of the tag patterns and updates the action settings accordingly. As a result - tags can be used to activate other tagger actions, as long as these other - taggers look for headers that haven't already be parsed.
For example you could tag client requests which use the - POST method, - then use this tag to activate another tagger that adds a tag if cookies - are sent, and then use a block action based on the cookie tag. This allows - the outcome of one action, to be input into a subsequent action. However if - you'd reverse the position of the described taggers, and activated the - method tagger based on the cookie tagger, no method tags would be created. - The method tagger would look for the request line, but at the time - the cookie tag is created, the request line has already been parsed.
While this is a limitation you should be aware of, this kind of - indirection is seldom needed anyway and even the example doesn't - make too much sense.
8.5. Actions
All actions are disabled by default, until they are explicitly enabled - somewhere in an actions file. Actions are turned on if preceded with a - "+", and turned off if preceded with a "-". So a - +action means "do that action", e.g. - +block means "please block URLs that match the - following patterns", and -block means "don't - block URLs that match the following patterns, even if +block - previously applied."
- Again, actions are invoked by placing them on a line, enclosed in curly braces and - separated by whitespace, like in - {+some-action -some-other-action{some-parameter}}, - followed by a list of URL patterns, one per line, to which they apply. - Together, the actions line and the following pattern lines make up a section - of the actions file.
- Actions fall into three categories:

- Boolean, i.e the action can only be "enabled" or - "disabled". Syntax: -

+name # enable action name - -name # disable action name
-
- Example: +handle-as-image -
- Parameterized, where some value is required in order to enable this type of action. - Syntax: -
+ +
+name{param} # enable action and set parameter to param, + .example.com/images/ads/ +
+
+ +
+ You can trace this process for URL patterns and any given URL by + visiting http://config.privoxy.org/show-url-info. +
+
+ Examples and more detail on this is provided in the Appendix, Troubleshooting: Anatomy of an + Action section. +
+
+
+
+ 8.4. Patterns +
+
+ As mentioned, Privoxy uses "patterns" to determine what actions might apply to + which sites and pages your browser attempts to access. These "patterns" use wild card type pattern matching to + achieve a high degree of flexibility. This allows one expression to + be expanded and potentially match against many similar patterns. +
+
+ Generally, an URL pattern has the form <host><port>/<path>, where the <host>, the <port> and the <path> are optional. (This is why the special + / pattern matches all URLs). Note that the + protocol portion of the URL pattern (e.g. http://) should not be included in the pattern. This is + assumed already! +
+
+ The pattern matching syntax is different for the host and path + parts of the URL. The host part uses a simple globbing type + matching technique, while the path part uses more flexible "Regular Expressions" (POSIX + 1003.2). +
+
+ The port part of a pattern is a decimal port number preceded by a + colon (:). If the host part contains a + numerical IPv6 address, it has to be put into angle brackets (<, >). +
+
+
+
+ www.example.com/ +
+
+
+ is a host-only pattern and will match any request to www.example.com, regardless of which + document on that server is requested. So ALL pages in this + domain would be covered by the scope of this action. Note + that a simple example.com is + different and would NOT match. +
+
+
+ www.example.com +
+
+
+ means exactly the same. For host-only patterns, the trailing + / may be omitted. +
+
+
+ www.example.com/index.html +
+
+
+ matches all the documents on www.example.com whose name starts with /index.html. +
+
+
+ www.example.com/index.html$ +
+
+
+ matches only the single document /index.html on www.example.com. +
+
+
+ /index.html$ +
+
+
+ matches the document /index.html, + regardless of the domain, i.e. on any web server anywhere. +
+
+
+ / +
+
+
+ Matches any URL because there's no requirement for either the + domain or the path to match anything. +
+
+
+ :8000/ +
+
+
+ Matches any URL pointing to TCP port 8000. +
+
+
+ 10.0.0.1/ +
+
+
+ Matches any URL with the host address 10.0.0.1. (Note that the real URL uses plain + brackets, not angle brackets.) +
+
+
+ <2001:db8::1>/ +
+
+
+ Matches any URL with the host address 2001:db8::1. (Note that the real URL uses + plain brackets, not angle brackets.) +
+
+
+ index.html +
+
+
+ matches nothing, since it would be interpreted as a domain + name and there is no top-level domain called .html. So its a mistake. +
+
+
+
+
+
+ 8.4.1. The Host Pattern +
+
+ The matching of the host part offers some flexible options: if + the host pattern starts or ends with a dot, it becomes unanchored + at that end. The host pattern is often referred to as domain + pattern as it is usually used to match domain names and not IP + addresses. For example: +
+
+
+
+ .example.com +
+
+
+ matches any domain with first-level domain com and second-level domain example. For example www.example.com, example.com and foo.bar.baz.example.com. Note that it + wouldn't match if the second-level domain was another-example. +
+
+
+ www. +
+
+
+ matches any domain that STARTS with www. (It also matches the domain www but most of the time that doesn't + matter.) +
+
+
+ .example. +
+
+
+ matches any domain that CONTAINS .example.. And, by the way, also included + would be any files or documents that exist within that + domain since no path limitations are specified. (Correctly + speaking: It matches any FQDN that contains example as a domain.) This might be www.example.com, news.example.de, or www.example.net/cgi/testing.pl for instance. + All these cases are matched. +
+
+
+
+
+ Additionally, there are wild-cards that you can use in the domain + names themselves. These work similarly to shell globbing type + wild-cards: "*" represents zero or + more arbitrary characters (this is equivalent to the "Regular Expression" based + syntax of ".*"), "?" represents any single character (this is + equivalent to the regular expression syntax of a simple "."), and you can define "character classes" in square brackets which is + similar to the same regular expression technique. All of this can + be freely mixed: +
+
+
+
+ ad*.example.com +
+
+
+ matches "adserver.example.com", + "ads.example.com", etc but not + "sfads.example.com" +
+
+
+ *ad*.example.com +
+
+
+ matches all of the above, and then some. +
+
+
+ .?pix.com +
+
+
+ matches www.ipix.com, pictures.epix.com, a.b.c.d.e.upix.com etc. +
+
+
+ www[1-9a-ez].example.c* +
+
+
+ matches www1.example.com, www4.example.cc, wwwd.example.cy, wwwz.example.com etc., but not wwww.example.com. +
+
+
+
+
+ While flexible, this is not the sophistication of full regular + expression based syntax. +
+
+
+
+ 8.4.2. The Path Pattern +
+
+ Privoxy uses "modern" POSIX 1003.2 "Regular Expressions" for + matching the path portion (after the slash), and is thus more + flexible. +
+
+ There is an Appendix with a + brief quick-start into regular expressions, you also might want + to have a look at your operating system's documentation on + regular expressions (try man re_format). +
+
+ Note that the path pattern is automatically left-anchored at the + "/", i.e. it matches as if it would + start with a "^" (regular expression + speak for the beginning of a line). +
+
+ Please also note that matching in the path is CASE INSENSITIVE by + default, but you can switch to case sensitive at any point in the + pattern by using the "(?-i)" switch: + www.example.com/(?-i)PaTtErN.* will + match only documents whose path starts with PaTtErN in exactly this capitalization. +
+
+
+
+ .example.com/.* +
+
+
+ Is equivalent to just ".example.com", since any documents within + that domain are matched with or without the ".*" regular expression. This is redundant +
+
+
+ .example.com/.*/index.html$ +
+
+
+ Will match any page in the domain of "example.com" that is named "index.html", and that is part of some path. + For example, it matches "www.example.com/testing/index.html" but NOT + "www.example.com/index.html" + because the regular expression called for at least two + "/'s", thus the path + requirement. It also would match "www.example.com/testing/index_html", + because of the special meta-character ".". +
+
+
+ .example.com/(.*/)?index\.html$ +
+
+
+ This regular expression is conditional so it will match any + page named "index.html" + regardless of path which in this case can have one or more + "/'s". And this one must contain + exactly ".html" (but does not + have to end with that!). +
+
+
+ .example.com/(.*/)(ads|banners?|junk) +
+
+
+ This regular expression will match any path of "example.com" that contains any of the words + "ads", "banner", "banners" (because of the "?") or "junk". + The path does not have to end in these words, just contain + them. +
+
+
+ .example.com/(.*/)(ads|banners?|junk)/.*\.(jpe?g|gif|png)$ +
+
+
+ This is very much the same as above, except now it must end + in either ".jpg", ".jpeg", ".gif" + or ".png". So this one is + limited to common image formats. +
+
+
+
+
+ There are many, many good examples to be found in default.action, and more tutorials below in Appendix on regular expressions. +
+
+
+
+ 8.4.3. The Request Tag Pattern +
+
+ Request tag patterns are used to change the applying actions + based on the request's tags. Tags can be created based on HTTP + headers with either the client-header-tagger + or the server-header-tagger + action. +
+
+ Request tag patterns have to start with "TAG:", so Privoxy can tell them apart from other + patterns. Everything after the colon including white space, is + interpreted as a regular expression with path pattern syntax, + except that tag patterns aren't left-anchored automatically + (Privoxy doesn't silently add a + "^", you have to do it yourself if you + need it). +
+
+ To match all requests that are tagged with "foo" your pattern line should be "TAG:^foo$", "TAG:foo" + would work as well, but it would also match requests whose tags + contain "foo" somewhere. "TAG: foo" wouldn't work as it requires white + space. +
+
+ Sections can contain URL and request tag patterns at the same + time, but request tag patterns are checked after the URL patterns + and thus always overrule them, even if they are located before + the URL patterns. +
+
+ Once a new request tag is added, Privoxy checks right away if + it's matched by one of the request tag patterns and updates the + action settings accordingly. As a result request tags can be used + to activate other tagger actions, as long as these other taggers + look for headers that haven't already be parsed. +
+
+ For example you could tag client requests which use the POST method, then use this tag to activate + another tagger that adds a tag if cookies are sent, and then use + a block action based on the cookie tag. This allows the outcome + of one action, to be input into a subsequent action. However if + you'd reverse the position of the described taggers, and + activated the method tagger based on the cookie tagger, no method + tags would be created. The method tagger would look for the + request line, but at the time the cookie tag is created, the + request line has already been parsed. +
+
+ While this is a limitation you should be aware of, this kind of + indirection is seldom needed anyway and even the example doesn't + make too much sense. +
+
+
+
+ 8.4.4. The Negative Request Tag + Patterns +
+
+ To match requests that do not have a certain request tag, specify + a negative tag pattern by prefixing the tag pattern line with + either "NO-REQUEST-TAG:" or "NO-RESPONSE-TAG:" instead of "TAG:". +
+
+ Negative request tag patterns created with "NO-REQUEST-TAG:" are checked after all client + headers are scanned, the ones created with "NO-RESPONSE-TAG:" are checked after all server + headers are scanned. In both cases all the created tags are + considered. +
+
+
+
+ 8.4.5. The Client Tag Pattern +
+
+ + + + + + + +
+ Warning +
+
+ This is an experimental feature. The syntax is likely to + change in future versions. +
+
+
+
+ Client tag patterns are not set based on HTTP headers but based + on the client's IP address. Users can enable them themselves, but + the Privoxy admin controls which tags are available and what + their effect is. +
+
+ After a client-specific tag has been defined with the client-specific-tag, + directive, action sections can be activated based on the tag by + using a CLIENT-TAG pattern. The CLIENT-TAG pattern is evaluated + at the same priority as URL patterns, as a result the last + matching pattern wins. Tags that are created based on client or + server headers are evaluated later on and can overrule CLIENT-TAG + and URL patterns! +
+
+ The tag is set for all requests that come from clients that + requested it to be set. Note that "clients" are differentiated by + IP address, if the IP address changes the tag has to be requested + again. +
+
+ Clients can request tags to be set by using the CGI interface http://config.privoxy.org/client-tags. +
+
+ Example: +
+
+
+ + + + +
+
+# If the admin defined the client-specific-tag circumvent-blocks, +# and the request comes from a client that previously requested +# the tag to be set, overrule all previous +block actions that +# are enabled based on URL to CLIENT-TAG patterns. +{-block} +CLIENT-TAG:^circumvent-blocks$ + +# This section is not overruled because it's located after +# the previous one. +{+block{Nobody is supposed to request this.}} +example.org/blocked-example-page +
+
+
+
+
+
+ 8.5. Actions +
+
+ All actions are disabled by default, until they are explicitly + enabled somewhere in an actions file. Actions are turned on if + preceded with a "+", and turned off if + preceded with a "-". So a +action means "do that + action", e.g. +block means "please block URLs that match the following + patterns", and -block means "don't block URLs that match the following patterns, + even if +block previously + applied." +
+
+ Again, actions are invoked by placing them on a line, enclosed in + curly braces and separated by whitespace, like in {+some-action -some-other-action{some-parameter}}, + followed by a list of URL patterns, one per line, to which they + apply. Together, the actions line and the following pattern lines + make up a section of the actions file. +
+
+ Actions fall into three categories: +
+
+
+
+
+
+ Boolean, i.e the action can only be "enabled" or "disabled". Syntax: +
+
+
+ + + + +
+
+ +name # enable action name + -name # disable action name +
+
+ +
+ Example: +handle-as-image +
+
+
+
+ Parameterized, where some value is required in order to enable + this type of action. Syntax: +
+
+
+ + +
+
+ +name{param} # enable action and set parameter to param, # overwriting parameter from previous match if necessary - -name # disable action. The parameter can be omitted
-
Note that if the URL matches multiple positive forms of a parameterized action, - the last match wins, i.e. the params from earlier matches are simply ignored. -
- Example: +hide-user-agent{Mozilla/5.0 (X11; U; FreeBSD i386; en-US; rv:1.8.1.4) Gecko/20070602 Firefox/2.0.0.4} -
- Multi-value. These look exactly like parameterized actions, - but they behave differently: If the action applies multiple times to the - same URL, but with different parameters, all the parameters - from all matches are remembered. This is used for actions - that can be executed for the same request repeatedly, like adding multiple - headers, or filtering through multiple filters. Syntax: -
+ +
+name{param} # enable action and add param to the list of parameters - -name{param} # remove the parameter param from the list of parameters + -name # disable action. The parameter can be omitted +
+
+ +
+ Note that if the URL matches multiple positive forms of a + parameterized action, the last match wins, i.e. the params from + earlier matches are simply ignored. +
+
+ Example: +hide-user-agent{Mozilla/5.0 (X11; + U; FreeBSD i386; en-US; rv:1.8.1.4) Gecko/20070602 + Firefox/2.0.0.4} +
+
+
+
+ Multi-value. These look exactly like parameterized actions, but + they behave differently: If the action applies multiple times + to the same URL, but with different parameters, all the parameters + from all + matches are remembered. This is used for actions that can be + executed for the same request repeatedly, like adding multiple + headers, or filtering through multiple filters. Syntax: +
+
+
+ + +
+
+ +name{param} # enable action and add param to the list of parameters + -name{param} # remove the parameter param from the list of parameters # If it was the last one left, disable the action. - -name # disable this action completely and remove all parameters from the list
-
- Examples: +add-header{X-Fun-Header: Some text} and - +filter{html-annoyances} -
If nothing is specified in any actions file, no "actions" are - taken. So in this case Privoxy would just be a - normal, non-blocking, non-filtering proxy. You must specifically enable the - privacy and blocking features you need (although the provided default actions - files will give a good starting point).
Later defined action sections always over-ride earlier ones of the same type. - So exceptions to any rules you make, should come in the latter part of the file (or - in a file that is processed later when using multiple actions files such - as user.action). For multi-valued actions, the actions - are applied in the order they are specified. Actions files are processed in - the order they are defined in config (the default - installation has three actions files). It also quite possible for any given - URL to match more than one "pattern" (because of wildcards and - regular expressions), and thus to trigger more than one set of actions! Last - match wins.
The list of valid Privoxy actions are:
8.5.1. add-header
Typical use:
Confuse log analysis, custom applications
Effect:
Sends a user defined HTTP header to the web server. -
Type:
Multi-value.
Parameter:
Any string value is possible. Validity of the defined HTTP headers is not checked. - It is recommended that you use the "X-" prefix - for custom headers. -
Notes:
This action may be specified multiple times, in order to define multiple - headers. This is rarely needed for the typical user. If you don't know what - "HTTP headers" are, you definitely don't need to worry about this - one. -
Example usage:

+add-header{X-User-Tracking: sucks}
-
8.5.2. block
Typical use:
Block ads or other unwanted content
Effect:
Requests for URLs to which this action applies are blocked, i.e. the - requests are trapped by Privoxy and the requested URL is never retrieved, - but is answered locally with a substitute page or image, as determined by - the handle-as-image, - set-image-blocker, and - handle-as-empty-document actions. - -
Type:
Parameterized.
Parameter:
A block reason that should be given to the user.
Notes:
Privoxy sends a special "BLOCKED" page - for requests to blocked pages. This page contains the block reason given as - parameter, a link to find out why the block action applies, and a click-through - to the blocked content (the latter only if the force feature is available and - enabled). -
- A very important exception occurs if both - block and handle-as-image, - apply to the same request: it will then be replaced by an image. If - set-image-blocker - (see below) also applies, the type of image will be determined by its parameter, - if not, the standard checkerboard pattern is sent. -
It is important to understand this process, in order - to understand how Privoxy deals with - ads and other unwanted content. Blocking is a core feature, and one - upon which various other features depend. -
The filter - action can perform a very similar task, by "blocking" - banner images and other content through rewriting the relevant URLs in the - document's HTML source, so they don't get requested in the first place. - Note that this is a totally different technique, and it's easy to confuse the two. -
Example usage (section):
+ +
{+block{No nasty stuff for you.}} + -name # disable this action completely and remove all parameters from the list +
+
+ +
+ Examples: +add-header{X-Fun-Header: Some + text} and +filter{html-annoyances} +
+ + + +
+ If nothing is specified in any actions file, no "actions" are taken. So in this case Privoxy would just be a normal, non-blocking, + non-filtering proxy. You must specifically enable the privacy and + blocking features you need (although the provided default actions + files will give a good starting point). +
+
+ Later defined action sections always over-ride earlier ones of the + same type. So exceptions to any rules you make, should come in the + latter part of the file (or in a file that is processed later when + using multiple actions files such as user.action). For multi-valued actions, the actions + are applied in the order they are specified. Actions files are + processed in the order they are defined in config (the default installation has three actions + files). It also quite possible for any given URL to match more than + one "pattern" (because of wildcards and + regular expressions), and thus to trigger more than one set of + actions! Last match wins. +
+
+ The list of valid Privoxy actions + are: +
+
+
+ 8.5.1. add-header +
+
+
+
+ Typical use: +
+
+
+ Confuse log analysis, custom applications +
+
+
+ Effect: +
+
+
+ Sends a user defined HTTP header to the web server. +
+
+
+ Type: +
+
+
+ Multi-value. +
+
+
+ Parameter: +
+
+
+ Any string value is possible. Validity of the defined HTTP + headers is not checked. It is recommended that you use the + "X-" + prefix for custom headers. +
+
+
+ Notes: +
+
+
+ This action may be specified multiple times, in order to + define multiple headers. This is rarely needed for the + typical user. If you don't know what "HTTP headers" are, you definitely don't + need to worry about this one. +
+
+ Headers added by this action are not modified by other + actions. +
+
+
+ Example usage: +
+
+
+
+ + + + +
+
+# Add a DNT ("Do not track") header to all requests, +# event to those that already have one. +# +# This is just an example, not a recommendation. +# +# There is no reason to believe that user-tracking websites care +# about the DNT header and depending on the User-Agent, adding the +# header may make user-tracking easier. +{+add-header{DNT: 1}} +/ +
+
+
+
+
+
+
+
+ 8.5.2. block +
+
+
+
+ Typical use: +
+
+
+ Block ads or other unwanted content +
+
+
+ Effect: +
+
+
+ Requests for URLs to which this action applies are blocked, + i.e. the requests are trapped by Privoxy and the requested URL is never + retrieved, but is answered locally with a substitute page + or image, as determined by the handle-as-image, + set-image-blocker, + and handle-as-empty-document + actions. +
+
+
+ Type: +
+
+
+ Parameterized. +
+
+
+ Parameter: +
+
+
+ A block reason that should be given to the user. +
+
+
+ Notes: +
+
+
+ Privoxy sends a special + "BLOCKED" page for requests to + blocked pages. This page contains the block reason given as + parameter, a link to find out why the block action applies, + and a click-through to the blocked content (the latter only + if the force feature is available and enabled). +
+
+ A very important exception occurs if both block and handle-as-image, + apply to the same request: it will then be replaced by an + image. If set-image-blocker + (see below) also applies, the type of image will be + determined by its parameter, if not, the standard + checkerboard pattern is sent. +
+
+ It is important to understand this process, in order to + understand how Privoxy + deals with ads and other unwanted content. Blocking is a + core feature, and one upon which various other features + depend. +
+
+ The filter action can + perform a very similar task, by "blocking" banner images and other content + through rewriting the relevant URLs in the document's HTML + source, so they don't get requested in the first place. + Note that this is a totally different technique, and it's + easy to confuse the two. +
+
+
+ Example usage (section): +
+
+
+
+ + +
+
+{+block{No nasty stuff for you.}} # Block and replace with "blocked" page .nasty-stuff.example.com -{+block{Doubleclick banners.} +handle-as-image} +{+block{Doubleclick banners.} +handle-as-image} # Block and replace with image .ad.doubleclick.net .ads.r.us/banners/ -{+block{Layered ads.} +handle-as-empty-document} +{+block{Layered ads.} +handle-as-empty-document} # Block and then ignore - adserver.example.net/.*\.js$
-
8.5.3. client-header-filter
Typical use:
Rewrite or remove single client headers. -
Effect:
All client headers to which this action applies are filtered on-the-fly through - the specified regular expression based substitutions. -
Type:
Parameterized.
Parameter:
The name of a client-header filter, as defined in one of the - filter files. -
Notes:
Client-header filters are applied to each header on its own, not to - all at once. This makes it easier to diagnose problems, but on the downside - you can't write filters that only change header x if header y's value is z. - You can do that by using tags though. -
Client-header filters are executed after the other header actions have finished - and use their output as input. -
If the request URL gets changed, Privoxy will detect that and use the new - one. This can be used to rewrite the request destination behind the client's - back, for example to specify a Tor exit relay for certain requests. -
Please refer to the filter file chapter - to learn which client-header filters are available by default, and how to - create your own. -
Example usage (section):
+ +
# Hide Tor exit notation in Host and Referer Headers + adserver.example.net/.*\.js$ +
+
+
+
+
+
+
+
+ 8.5.3. + change-x-forwarded-for +
+
+
+
+ Typical use: +
+
+
+ Improve privacy by not forwarding the source of the request + in the HTTP headers. +
+
+
+ Effect: +
+
+
+ Deletes the "X-Forwarded-For:" + HTTP header from the client request, or adds a new one. +
+
+
+ Type: +
+
+
+ Parameterized. +
+
+
+ Parameter: +
+
+
+
+
+ "block" to delete the + header. +
+
+
+
+ "add" to create the header + (or append the client's IP address to an already + existing one). +
+
+
+
+
+ Notes: +
+
+
+ It is safe and recommended to use block. +
+
+ Forwarding the source address of the request may make sense + in some multi-user setups but is also a privacy risk. +
+
+
+ Example usage: +
+
+
+
+ + + + +
+
++change-x-forwarded-for{block} +
+
+
+
+
+
+
+
+ 8.5.4. client-header-filter +
+
+
+
+ Typical use: +
+
+
+ Rewrite or remove single client headers. +
+
+
+ Effect: +
+
+
+ All client headers to which this action applies are + filtered on-the-fly through the specified regular + expression based substitutions. +
+
+
+ Type: +
+
+
+ Multi-value. +
+
+
+ Parameter: +
+
+
+ The name of a client-header filter, as defined in one of + the filter files. +
+
+
+ Notes: +
+
+
+ Client-header filters are applied to each header on its + own, not to all at once. This makes it easier to diagnose + problems, but on the downside you can't write filters that + only change header x if header y's value is z. You can do + that by using tags though. +
+
+ Client-header filters are executed after the other header + actions have finished and use their output as input. +
+
+ If the request URI gets changed, Privoxy will detect that and use the + new one. This can be used to rewrite the request + destination behind the client's back, for example to + specify a Tor exit relay for certain requests. +
+
+ Please refer to the filter file + chapter to learn which client-header filters are + available by default, and how to create your own. +
+
+
+ Example usage (section): +
+
+
+
+ + +
+
+# Hide Tor exit notation in Host and Referer Headers {+client-header-filter{hide-tor-exit-notation}} / -
-
8.5.4. client-header-tagger
Typical use:
Block requests based on their headers. -
Effect:
Client headers to which this action applies are filtered on-the-fly through - the specified regular expression based substitutions, the result is used as - tag. -
Type:
Parameterized.
Parameter:
The name of a client-header tagger, as defined in one of the - filter files. -
Notes:
Client-header taggers are applied to each header on its own, - and as the header isn't modified, each tagger "sees" - the original. -
Client-header taggers are the first actions that are executed - and their tags can be used to control every other action. -
Example usage (section):
+ +
# Tag every request with the User-Agent header + +
+
+
+
+
+
+
+
+ 8.5.5. client-header-tagger +
+
+
+
+ Typical use: +
+
+
+ Block requests based on their headers. +
+
+
+ Effect: +
+
+
+ Client headers to which this action applies are filtered + on-the-fly through the specified regular expression based + substitutions, the result is used as tag. +
+
+
+ Type: +
+
+
+ Multi-value. +
+
+
+ Parameter: +
+
+
+ The name of a client-header tagger, as defined in one of + the filter files. +
+
+
+ Notes: +
+
+
+ Client-header taggers are applied to each header on its + own, and as the header isn't modified, each tagger "sees" the original. +
+
+ Client-header taggers are the first actions that are + executed and their tags can be used to control every other + action. +
+
+
+ Example usage (section): +
+
+
+
+ + +
+
+# Tag every request with the User-Agent header {+client-header-tagger{user-agent}} / @@ -2188,2439 +1676,2023 @@ TAG:^User-Agent: RPM APT-HTTP/ TAG:^User-Agent: fetch libfetch/ TAG:^User-Agent: Ubuntu APT-HTTP/ TAG:^User-Agent: MPlayer/ -
-
8.5.5. content-type-overwrite
Typical use:
Stop useless download menus from popping up, or change the browser's rendering mode
Effect:
Replaces the "Content-Type:" HTTP server header. -
Type:
Parameterized.
Parameter:
Any string. -
Notes:
The "Content-Type:" HTTP server header is used by the - browser to decide what to do with the document. The value of this - header can cause the browser to open a download menu instead of - displaying the document by itself, even if the document's format is - supported by the browser. -
The declared content type can also affect which rendering mode - the browser chooses. If XHTML is delivered as "text/html", - many browsers treat it as yet another broken HTML document. - If it is send as "application/xml", browsers with - XHTML support will only display it, if the syntax is correct. -
If you see a web site that proudly uses XHTML buttons, but sets - "Content-Type: text/html", you can use Privoxy - to overwrite it with "application/xml" and validate - the web master's claim inside your XHTML-supporting browser. - If the syntax is incorrect, the browser will complain loudly. -
You can also go the opposite direction: if your browser prints - error messages instead of rendering a document falsely declared - as XHTML, you can overwrite the content type with - "text/html" and have it rendered as broken HTML document. -
By default content-type-overwrite only replaces - "Content-Type:" headers that look like some kind of text. - If you want to overwrite it unconditionally, you have to combine it with - force-text-mode. - This limitation exists for a reason, think twice before circumventing it. -
Most of the time it's easier to replace this action with a custom - server-header filter. - It allows you to activate it for every document of a certain site and it will still - only replace the content types you aimed at. -
Of course you can apply content-type-overwrite - to a whole site and then make URL based exceptions, but it's a lot - more work to get the same precision. -
Example usage (sections):
+ +
# Check if www.example.net/ really uses valid XHTML + +
+
+ +
+
+ + + + +
+
+# Tag all requests with the Range header set +{+client-header-tagger{range-requests}} +/ + +# Disable filtering for the tagged requests. +# +# With filtering enabled Privoxy would remove the Range headers +# to be able to filter the whole response. The downside is that +# it prevents clients from resuming downloads or skipping over +# parts of multimedia files. +{-filter -deanimate-gifs} +TAG:^RANGE-REQUEST$ + +
+
+
+
+
+
+
+
+ 8.5.6. + content-type-overwrite +
+
+
+
+ Typical use: +
+
+
+ Stop useless download menus from popping up, or change the + browser's rendering mode +
+
+
+ Effect: +
+
+
+ Replaces the "Content-Type:" + HTTP server header. +
+
+
+ Type: +
+
+
+ Parameterized. +
+
+
+ Parameter: +
+
+
+ Any string. +
+
+
+ Notes: +
+
+
+ The "Content-Type:" HTTP server + header is used by the browser to decide what to do with the + document. The value of this header can cause the browser to + open a download menu instead of displaying the document by + itself, even if the document's format is supported by the + browser. +
+
+ The declared content type can also affect which rendering + mode the browser chooses. If XHTML is delivered as "text/html", many browsers treat it as + yet another broken HTML document. If it is send as "application/xml", browsers with XHTML + support will only display it, if the syntax is correct. +
+
+ If you see a web site that proudly uses XHTML buttons, but + sets "Content-Type: text/html", + you can use Privoxy to + overwrite it with "application/xml" and validate the web + master's claim inside your XHTML-supporting browser. If the + syntax is incorrect, the browser will complain loudly. +
+
+ You can also go the opposite direction: if your browser + prints error messages instead of rendering a document + falsely declared as XHTML, you can overwrite the content + type with "text/html" and have + it rendered as broken HTML document. +
+
+ By default content-type-overwrite + only replaces "Content-Type:" + headers that look like some kind of text. If you want to + overwrite it unconditionally, you have to combine it with + force-text-mode. + This limitation exists for a reason, think twice before + circumventing it. +
+
+ Most of the time it's easier to replace this action with a + custom server-header + filter. It allows you to activate it for every + document of a certain site and it will still only replace + the content types you aimed at. +
+
+ Of course you can apply content-type-overwrite to a whole site and + then make URL based exceptions, but it's a lot more work to + get the same precision. +
+
+
+ Example usage (sections): +
+
+
+
+ + +
+
+# Check if www.example.net/ really uses valid XHTML { +content-type-overwrite{application/xml} } www.example.net/ # but leave the content type unmodified if the URL looks like a style sheet {-content-type-overwrite} www.example.net/.*\.css$ -www.example.net/.*style
-
8.5.6. crunch-client-header
Typical use:
Remove a client header Privoxy has no dedicated action for.
Effect:
Deletes every header sent by the client that contains the string the user supplied as parameter. -
Type:
Parameterized.
Parameter:
Any string. -
Notes:
This action allows you to block client headers for which no dedicated - Privoxy action exists. - Privoxy will remove every client header that - contains the string you supplied as parameter. -
Regular expressions are not supported and you can't - use this action to block different headers in the same request, unless - they contain the same string. -
crunch-client-header is only meant for quick tests. - If you have to block several different headers, or only want to modify - parts of them, you should use a - client-header filter. -
Warning
Don't block any header without understanding the consequences. -
Example usage (section):
+ +
# Block the non-existent "Privacy-Violation:" client header +www.example.net/.*style +
+
+
+
+
+
+
+
+ 8.5.7. crunch-client-header +
+
+
+
+ Typical use: +
+
+
+ Remove a client header Privoxy has no dedicated action for. +
+
+
+ Effect: +
+
+
+ Deletes every header sent by the client that contains the + string the user supplied as parameter. +
+
+
+ Type: +
+
+
+ Parameterized. +
+
+
+ Parameter: +
+
+
+ Any string. +
+
+
+ Notes: +
+
+
+ This action allows you to block client headers for which no + dedicated Privoxy action + exists. Privoxy will + remove every client header that contains the string you + supplied as parameter. +
+
+ Regular expressions are not supported and you can't use this + action to block different headers in the same request, + unless they contain the same string. +
+
+ crunch-client-header is only meant + for quick tests. If you have to block several different + headers, or only want to modify parts of them, you should + use a client-header + filter. +
+
+ + + + + + + +
+ Warning +
+
+ Don't block any header without understanding the + consequences. +
+
+
+
+
+ Example usage (section): +
+
+
+
+ + +
+
+# Block the non-existent "Privacy-Violation:" client header { +crunch-client-header{Privacy-Violation:} } / -
-
8.5.7. crunch-if-none-match
Typical use:
Prevent yet another way to track the user's steps between sessions.
Effect:
Deletes the "If-None-Match:" HTTP client header. -
Type:
Boolean.
Parameter:
N/A -
Notes:
Removing the "If-None-Match:" HTTP client header - is useful for filter testing, where you want to force a real - reload instead of getting status code "304" which - would cause the browser to use a cached copy of the page. -
It is also useful to make sure the header isn't used as a cookie - replacement (unlikely but possible). -
Blocking the "If-None-Match:" header shouldn't cause any - caching problems, as long as the "If-Modified-Since:" header - isn't blocked or missing as well. -
It is recommended to use this action together with - hide-if-modified-since - and - overwrite-last-modified. -
Example usage (section):
+ +
# Let the browser revalidate cached documents but don't + +
+
+
+
+
+
+
+
+ 8.5.8. crunch-if-none-match +
+
+
+
+ Typical use: +
+
+
+ Prevent yet another way to track the user's steps between + sessions. +
+
+
+ Effect: +
+
+
+ Deletes the "If-None-Match:" + HTTP client header. +
+
+
+ Type: +
+
+
+ Boolean. +
+
+
+ Parameter: +
+
+
+ N/A +
+
+
+ Notes: +
+
+
+ Removing the "If-None-Match:" + HTTP client header is useful for filter testing, where you + want to force a real reload instead of getting status code + "304" which would cause the + browser to use a cached copy of the page. +
+
+ It is also useful to make sure the header isn't used as a + cookie replacement (unlikely but possible). +
+
+ Blocking the "If-None-Match:" + header shouldn't cause any caching problems, as long as the + "If-Modified-Since:" header + isn't blocked or missing as well. +
+
+ It is recommended to use this action together with hide-if-modified-since + and overwrite-last-modified. +
+
+
+ Example usage (section): +
+
+
+
+ + +
+
+# Let the browser revalidate cached documents but don't # allow the server to use the revalidation headers for user tracking. {+hide-if-modified-since{-60} \ +overwrite-last-modified{randomize} \ +crunch-if-none-match} -/
-
8.5.8. crunch-incoming-cookies
Typical use:
Prevent the web server from setting HTTP cookies on your system -
Effect:
Deletes any "Set-Cookie:" HTTP headers from server replies. -
Type:
Boolean.
Parameter:
N/A -
Notes:
This action is only concerned with incoming HTTP cookies. For - outgoing HTTP cookies, use - crunch-outgoing-cookies. - Use both to disable HTTP cookies completely. -
It makes no sense at all to use this action in conjunction - with the session-cookies-only action, - since it would prevent the session cookies from being set. See also - filter-content-cookies. -
Example usage:

+crunch-incoming-cookies
-
8.5.9. crunch-server-header
Typical use:
Remove a server header Privoxy has no dedicated action for.
Effect:
Deletes every header sent by the server that contains the string the user supplied as parameter. -
Type:
Parameterized.
Parameter:
Any string. -
Notes:
This action allows you to block server headers for which no dedicated - Privoxy action exists. Privoxy - will remove every server header that contains the string you supplied as parameter. -
Regular expressions are not supported and you can't - use this action to block different headers in the same request, unless - they contain the same string. -
crunch-server-header is only meant for quick tests. - If you have to block several different headers, or only want to modify - parts of them, you should use a custom - server-header filter. -
Warning
Don't block any header without understanding the consequences. -
Example usage (section):
+ +
# Crunch server headers that try to prevent caching +/ +
+
+
+
+
+
+
+
+ 8.5.9. + crunch-incoming-cookies +
+
+
+
+ Typical use: +
+
+
+ Prevent the web server from setting HTTP cookies on your + system +
+
+
+ Effect: +
+
+
+ Deletes any "Set-Cookie:" HTTP + headers from server replies. +
+
+
+ Type: +
+
+
+ Boolean. +
+
+
+ Parameter: +
+
+
+ N/A +
+
+
+ Notes: +
+
+
+ This action is only concerned with incoming HTTP + cookies. For outgoing HTTP cookies, use crunch-outgoing-cookies. + Use both to disable HTTP cookies + completely. +
+
+ It makes no + sense at all to use this action in conjunction + with the session-cookies-only + action, since it would prevent the session cookies from + being set. See also filter-content-cookies. +
+
+
+ Example usage: +
+
+
+
+ + + + +
+
++crunch-incoming-cookies +
+
+
+
+
+
+
+
+ 8.5.10. crunch-server-header +
+
+
+
+ Typical use: +
+
+
+ Remove a server header Privoxy has no dedicated action for. +
+
+
+ Effect: +
+
+
+ Deletes every header sent by the server that contains the + string the user supplied as parameter. +
+
+
+ Type: +
+
+
+ Parameterized. +
+
+
+ Parameter: +
+
+
+ Any string. +
+
+
+ Notes: +
+
+
+ This action allows you to block server headers for which no + dedicated Privoxy action + exists. Privoxy will + remove every server header that contains the string you + supplied as parameter. +
+
+ Regular expressions are not supported and you can't use this + action to block different headers in the same request, + unless they contain the same string. +
+
+ crunch-server-header is only meant + for quick tests. If you have to block several different + headers, or only want to modify parts of them, you should + use a custom server-header + filter. +
+
+ + + + + + + +
+ Warning +
+
+ Don't block any header without understanding the + consequences. +
+
+
+
+
+ Example usage (section): +
+
+
+
+ + +
+
+# Crunch server headers that try to prevent caching { +crunch-server-header{no-cache} } -/
-
8.5.10. crunch-outgoing-cookies
Typical use:
Prevent the web server from reading any HTTP cookies from your system -
Effect:
Deletes any "Cookie:" HTTP headers from client requests. -
Type:
Boolean.
Parameter:
N/A -
Notes:
This action is only concerned with outgoing HTTP cookies. For - incoming HTTP cookies, use - crunch-incoming-cookies. - Use both to disable HTTP cookies completely. -
It makes no sense at all to use this action in conjunction - with the session-cookies-only action, - since it would prevent the session cookies from being read. -
Example usage:

+crunch-outgoing-cookies
-
8.5.11. deanimate-gifs
Typical use:
Stop those annoying, distracting animated GIF images.
Effect:
De-animate GIF animations, i.e. reduce them to their first or last image. -
Type:
Parameterized.
Parameter:
"last" or "first" -
Notes:
This will also shrink the images considerably (in bytes, not pixels!). If - the option "first" is given, the first frame of the animation - is used as the replacement. If "last" is given, the last - frame of the animation is used instead, which probably makes more sense for - most banner animations, but also has the risk of not showing the entire - last frame (if it is only a delta to an earlier frame). -
You can safely use this action with patterns that will also match non-GIF - objects, because no attempt will be made at anything that doesn't look like - a GIF. -
Example usage:

+deanimate-gifs{last}
-
8.5.12. downgrade-http-version
Typical use:
Work around (very rare) problems with HTTP/1.1
Effect:
Downgrades HTTP/1.1 client requests and server replies to HTTP/1.0. -
Type:
Boolean.
Parameter:
N/A -
Notes:
This is a left-over from the time when Privoxy - didn't support important HTTP/1.1 features well. It is left here for the - unlikely case that you experience HTTP/1.1 related problems with some server - out there. Not all HTTP/1.1 features and requirements are supported yet, - so there is a chance you might need this action. -
Example usage (section):

{+downgrade-http-version} -problem-host.example.com
-
8.5.13. fast-redirects
Typical use:
Fool some click-tracking scripts and speed up indirect links.
Effect:
Detects redirection URLs and redirects the browser without contacting - the redirection server first. -
Type:
Parameterized.
Parameter:
"simple-check" to just search for the string "http://" - to detect redirection URLs. -
"check-decoded-url" to decode URLs (if necessary) before searching - for redirection URLs. -
Notes:
- Many sites, like yahoo.com, don't just link to other sites. Instead, they - will link to some script on their own servers, giving the destination as a - parameter, which will then redirect you to the final target. URLs - resulting from this scheme typically look like: - "http://www.example.org/click-tracker.cgi?target=http%3a//www.example.net/". -
Sometimes, there are even multiple consecutive redirects encoded in the - URL. These redirections via scripts make your web browsing more traceable, - since the server from which you follow such a link can see where you go - to. Apart from that, valuable bandwidth and time is wasted, while your - browser asks the server for one redirect after the other. Plus, it feeds - the advertisers. -
This feature is currently not very smart and is scheduled for improvement. - If it is enabled by default, you will have to create some exceptions to - this action. It can lead to failures in several ways: -
Not every URLs with other URLs as parameters is evil. - Some sites offer a real service that requires this information to work. - For example a validation service needs to know, which document to validate. - fast-redirects assumes that every URL parameter that - looks like another URL is a redirection target, and will always redirect to - the last one. Most of the time the assumption is correct, but if it isn't, - the user gets redirected anyway. -
Another failure occurs if the URL contains other parameters after the URL parameter. - The URL: - "http://www.example.org/?redirect=http%3a//www.example.net/&foo=bar". - contains the redirection URL "http://www.example.net/", - followed by another parameter. fast-redirects doesn't know that - and will cause a redirect to "http://www.example.net/&foo=bar". - Depending on the target server configuration, the parameter will be silently ignored - or lead to a "page not found" error. You can prevent this problem by - first using the redirect action - to remove the last part of the URL, but it requires a little effort. -
To detect a redirection URL, fast-redirects only - looks for the string "http://", either in plain text - (invalid but often used) or encoded as "http%3a//". - Some sites use their own URL encoding scheme, encrypt the address - of the target server or replace it with a database id. In theses cases - fast-redirects is fooled and the request reaches the - redirection server where it probably gets logged. -
Example usage:
+ +
{ +fast-redirects{simple-check} } - one.example.com +/ +
+
+
+
+
+
+
+
+ 8.5.11. + crunch-outgoing-cookies +
+
+
+
+ Typical use: +
+
+
+ Prevent the web server from reading any HTTP cookies from + your system +
+
+
+ Effect: +
+
+
+ Deletes any "Cookie:" HTTP + headers from client requests. +
+
+
+ Type: +
+
+
+ Boolean. +
+
+
+ Parameter: +
+
+
+ N/A +
+
+
+ Notes: +
+
+
+ This action is only concerned with outgoing HTTP + cookies. For incoming HTTP cookies, use crunch-incoming-cookies. + Use both to disable HTTP cookies + completely. +
+
+ It makes no + sense at all to use this action in conjunction + with the session-cookies-only + action, since it would prevent the session cookies from + being read. +
+
+
+ Example usage: +
+
+
+
+ + + + +
+
++crunch-outgoing-cookies +
+
+
+
+
+
+
+
+ 8.5.12. deanimate-gifs +
+
+
+
+ Typical use: +
+
+
+ Stop those annoying, distracting animated GIF images. +
+
+
+ Effect: +
+
+
+ De-animate GIF animations, i.e. reduce them to their first + or last image. +
+
+
+ Type: +
+
+
+ Parameterized. +
+
+
+ Parameter: +
+
+
+ "last" or "first" +
+
+
+ Notes: +
+
+
+ This will also shrink the images considerably (in bytes, + not pixels!). If the option "first" is given, the first frame of the + animation is used as the replacement. If "last" is given, the last frame of the + animation is used instead, which probably makes more sense + for most banner animations, but also has the risk of not + showing the entire last frame (if it is only a delta to an + earlier frame). +
+
+ You can safely use this action with patterns that will also + match non-GIF objects, because no attempt will be made at + anything that doesn't look like a GIF. +
+
+
+ Example usage: +
+
+
+
+ + + + +
+
++deanimate-gifs{last} +
+
+
+
+
+
+
+
+ 8.5.13. + downgrade-http-version +
+
+
+
+ Typical use: +
+
+
+ Work around (very rare) problems with HTTP/1.1 +
+
+
+ Effect: +
+
+
+ Downgrades HTTP/1.1 client requests and server replies to + HTTP/1.0. +
+
+
+ Type: +
+
+
+ Boolean. +
+
+
+ Parameter: +
+
+
+ N/A +
+
+
+ Notes: +
+
+
+ This is a left-over from the time when Privoxy didn't support important + HTTP/1.1 features well. It is left here for the unlikely + case that you experience HTTP/1.1-related problems with + some server out there. +
+
+ Note that enabling this action is only a workaround. It + should not be enabled for sites that work without it. While + it shouldn't break any pages, it has an (usually negative) + performance impact. +
+
+ If you come across a site where enabling this action helps, + please report it, so the cause of the problem can be + analyzed. If the problem turns out to be caused by a bug in + Privoxy it should be fixed + so the following release works without the work around. +
+
+
+ Example usage (section): +
+
+
+
+ + + + +
+
+{+downgrade-http-version} +problem-host.example.com +
+
+
+
+
+
+
+
+ 8.5.14. external-filter +
+
+
+
+ Typical use: +
+
+
+ Modify content using a programming language of your choice. +
+
+
+ Effect: +
+
+
+ All instances of text-based type, most notably HTML and + JavaScript, to which this action applies, can be filtered + on-the-fly through the specified external filter. By + default plain text documents are exempted from filtering, + because web servers often use the text/plain MIME type for all files whose + type they don't know.) +
+
+
+ Type: +
+
+
+ Multi-value. +
+
+
+ Parameter: +
+
+
+ The name of an external content filter, as defined in the + filter file. External + filters can be defined in one or more files as defined by + the filterfile option in the + config file. +
+
+ When used in its negative form, and without parameters, + all + filtering with external filters is completely disabled. +
+
+
+ Notes: +
+
+
+ External filters are scripts or programs that can modify + the content in case common filters aren't powerful + enough. With the exception that this action doesn't use + pcrs-based filters, the notes in the filter section + apply. +
+
+ + + + + + + +
+ Warning +
+
+ Currently external filters are executed with Privoxy's privileges. + Only use external filters you understand and trust. +
+
+
+
+ This feature is experimental, the syntax + may change in the future. +
+
+
+ Example usage: +
+
+
+
+ + + + +
+
++external-filter{fancy-filter} +
+
+
+
+
+
+
+
+ 8.5.15. fast-redirects +
+
+
+
+ Typical use: +
+
+
+ Fool some click-tracking scripts and speed up indirect + links. +
+
+
+ Effect: +
+
+
+ Detects redirection URLs and redirects the browser without + contacting the redirection server first. +
+
+
+ Type: +
+
+
+ Parameterized. +
+
+
+ Parameter: +
+
+
+
+
+ "simple-check" to just + search for the string "http://" to detect redirection URLs. +
+
+
+
+ "check-decoded-url" to + decode URLs (if necessary) before searching for + redirection URLs. +
+
+
+
+
+ Notes: +
+
+
+ Many sites, like yahoo.com, don't just link to other sites. + Instead, they will link to some script on their own + servers, giving the destination as a parameter, which will + then redirect you to the final target. URLs resulting from + this scheme typically look like: "http://www.example.org/click-tracker.cgi?target=http%3a//www.example.net/". +
+
+ Sometimes, there are even multiple consecutive redirects + encoded in the URL. These redirections via scripts make + your web browsing more traceable, since the server from + which you follow such a link can see where you go to. Apart + from that, valuable bandwidth and time is wasted, while + your browser asks the server for one redirect after the + other. Plus, it feeds the advertisers. +
+
+ This feature is currently not very smart and is scheduled + for improvement. If it is enabled by default, you will have + to create some exceptions to this action. It can lead to + failures in several ways: +
+
+ Not every URLs with other URLs as parameters is evil. Some + sites offer a real service that requires this information + to work. For example a validation service needs to know, + which document to validate. fast-redirects assumes that every URL + parameter that looks like another URL is a redirection + target, and will always redirect to the last one. Most of + the time the assumption is correct, but if it isn't, the + user gets redirected anyway. +
+
+ Another failure occurs if the URL contains other parameters + after the URL parameter. The URL: "http://www.example.org/?redirect=http%3a//www.example.net/&foo=bar". + contains the redirection URL "http://www.example.net/", followed by + another parameter. fast-redirects + doesn't know that and will cause a redirect to "http://www.example.net/&foo=bar". + Depending on the target server configuration, the parameter + will be silently ignored or lead to a "page not found" error. You can prevent this + problem by first using the redirect action to + remove the last part of the URL, but it requires a little + effort. +
+
+ To detect a redirection URL, fast-redirects only looks for the string + "http://", either in plain text + (invalid but often used) or encoded as "http%3a//". Some sites use their own URL + encoding scheme, encrypt the address of the target server + or replace it with a database id. In theses cases fast-redirects is fooled and the + request reaches the redirection server where it probably + gets logged. +
+
+
+ Example usage: +
+
+
+
+ + +
+
+ { +fast-redirects{simple-check} } + one.example.com { +fast-redirects{check-decoded-url} } - another.example.com/testing
-
8.5.14. filter
Typical use:
Get rid of HTML and JavaScript annoyances, banner advertisements (by size), - do fun text replacements, add personalized effects, etc.
Effect:
All instances of text-based type, most notably HTML and JavaScript, to which - this action applies, can be filtered on-the-fly through the specified regular - expression based substitutions. (Note: as of version 3.0.3 plain text documents - are exempted from filtering, because web servers often use the - text/plain MIME type for all files whose type they don't know.) -
Type:
Parameterized.
Parameter:
The name of a content filter, as defined in the filter file. - Filters can be defined in one or more files as defined by the - filterfile - option in the config file. - default.filter is the collection of filters - supplied by the developers. Locally defined filters should go - in their own file, such as user.filter. -
When used in its negative form, - and without parameters, all filtering is completely disabled. -
Notes:
For your convenience, there are a number of pre-defined filters available - in the distribution filter file that you can use. See the examples below for - a list. -
Filtering requires buffering the page content, which may appear to - slow down page rendering since nothing is displayed until all content has - passed the filters. (It does not really take longer, but seems that way - since the page is not incrementally displayed.) This effect will be more - noticeable on slower connections. -
"Rolling your own" - filters requires a knowledge of - "Regular - Expressions" and - "HTML". - This is very powerful feature, and potentially very intrusive. - Filters should be used with caution, and where an equivalent - "action" is not available. -
The amount of data that can be filtered is limited to the - buffer-limit - option in the main config file. The - default is 4096 KB (4 Megs). Once this limit is exceeded, the buffered - data, and all pending data, is passed through unfiltered. -
Inappropriate MIME types, such as zipped files, are not filtered at all. - (Again, only text-based types except plain text). Encrypted SSL data - (from HTTPS servers) cannot be filtered either, since this would violate - the integrity of the secure transaction. In some situations it might - be necessary to protect certain text, like source code, from filtering - by defining appropriate -filter exceptions. -
Compressed content can't be filtered either, unless Privoxy - is compiled with zlib support (requires at least Privoxy 3.0.7), - in which case Privoxy will decompress the content before filtering - it. -
If you use a Privoxy version without zlib support, but want filtering to work on - as much documents as possible, even those that would normally be sent compressed, - you must use the prevent-compression - action in conjunction with filter. -
Content filtering can achieve some of the same effects as the - block - action, i.e. it can be used to block ads and banners. But the mechanism - works quite differently. One effective use, is to block ad banners - based on their size (see below), since many of these seem to be somewhat - standardized. -
Feedback with suggestions for new or - improved filters is particularly welcome! -
The below list has only the names and a one-line description of each - predefined filter. There are more - verbose explanations of what these filters do in the filter file chapter. -
Example usage (with filters from the distribution default.filter file). - See the Predefined Filters section for - more explanation on each:
-
+filter{js-annoyances} # Get rid of particularly annoying JavaScript abuse.
-
-
+filter{js-events} # Kill all JS event bindings and timers (Radically destructive! Only for extra nasty sites).
-
-
+filter{html-annoyances} # Get rid of particularly annoying HTML abuse.
-
-
+filter{content-cookies} # Kill cookies that come in the HTML or JS content.
-
-
+filter{refresh-tags} # Kill automatic refresh tags (for dial-on-demand setups).
-
-
+filter{unsolicited-popups} # Disable only unsolicited pop-up windows. Useful if your browser lacks this ability.
-
-
+filter{all-popups} # Kill all popups in JavaScript and HTML. Useful if your browser lacks this ability.
-
-
+filter{img-reorder} # Reorder attributes in <img> tags to make the banners-by-* filters more effective.
-
-
+filter{banners-by-size} # Kill banners by size.
-
-
+filter{banners-by-link} # Kill banners by their links to known clicktrackers.
-
-
+filter{webbugs} # Squish WebBugs (1x1 invisible GIFs used for user tracking).
-
-
+filter{tiny-textforms} # Extend those tiny textareas up to 40x80 and kill the hard wrap.
-
-
+filter{jumping-windows} # Prevent windows from resizing and moving themselves.
-
-
+filter{frameset-borders} # Give frames a border and make them resizable.
-
-
+filter{demoronizer} # Fix MS's non-standard use of standard charsets.
-
-
+filter{shockwave-flash} # Kill embedded Shockwave Flash objects.
-
-
+filter{quicktime-kioskmode} # Make Quicktime movies saveable.
-
-
+filter{fun} # Text replacements for subversive browsing fun!
-
-
+filter{crude-parental} # Crude parental filtering. Note that this filter doesn't work reliably.
-
-
+filter{ie-exploits} # Disable some known Internet Explorer bug exploits.
-
-
+filter{site-specifics} # Cure for site-specific problems. Don't apply generally!
-
-
+filter{no-ping} # Removes non-standard ping attributes in <a> and <area> tags.
-
-
+filter{google} # CSS-based block for Google text ads. Also removes a width limitation and the toolbar advertisement.
-
-
+filter{yahoo} # CSS-based block for Yahoo text ads. Also removes a width limitation.
-
-
+filter{msn} # CSS-based block for MSN text ads. Also removes tracking URLs and a width limitation.
-
-
+filter{blogspot} # Cleans up some Blogspot blogs. Read the fine print before using this.
-
8.5.15. force-text-mode
Typical use:
Force Privoxy to treat a document as if it was in some kind of text format.
Effect:
Declares a document as text, even if the "Content-Type:" isn't detected as such. -
Type:
Boolean.
Parameter:
N/A -
Notes:
As explained above, - Privoxy tries to only filter files that are - in some kind of text format. The same restrictions apply to - content-type-overwrite. - force-text-mode declares a document as text, - without looking at the "Content-Type:" first. -
Warning
Think twice before activating this action. Filtering binary data - with regular expressions can cause file damage. -
Example usage:

+force-text-mode -
-
8.5.16. forward-override
Typical use:
Change the forwarding settings based on User-Agent or request origin
Effect:
Overrules the forward directives in the configuration file. -
Type:
Multi-value.
Parameter:
"forward ." to use a direct connection without any additional proxies.
"forward 127.0.0.1:8123" to use the HTTP proxy listening at 127.0.0.1 port 8123. -
"forward-socks4a 127.0.0.1:9050 ." to use the socks4a proxy listening at - 127.0.0.1 port 9050. Replace "forward-socks4a" with "forward-socks4" - to use a socks4 connection (with local DNS resolution) instead, use "forward-socks5" - for socks5 connections (with remote DNS resolution). -
"forward-socks4a 127.0.0.1:9050 proxy.example.org:8000" to use the socks4a proxy - listening at 127.0.0.1 port 9050 to reach the HTTP proxy listening at proxy.example.org port 8000. - Replace "forward-socks4a" with "forward-socks4" to use a socks4 connection - (with local DNS resolution) instead, use "forward-socks5" - for socks5 connections (with remote DNS resolution). -
Notes:
This action takes parameters similar to the - forward directives in the configuration - file, but without the URL pattern. It can be used as replacement, but normally it's only - used in cases where matching based on the request URL isn't sufficient. -
Warning
Please read the description for the forward directives before - using this action. Forwarding to the wrong people will reduce your privacy and increase the - chances of man-in-the-middle attacks. -
If the ports are missing or invalid, default values will be used. This might change - in the future and you shouldn't rely on it. Otherwise incorrect syntax causes Privoxy - to exit. -
Use the show-url-info CGI page - to verify that your forward settings do what you thought the do. -
Example usage:
+ +
# Always use direct connections for requests previously tagged as -# "User-Agent: fetch libfetch/2.0" and make sure + another.example.com/testing +
+
+
+
+
+
+
+
+ 8.5.16. filter +
+
+
+
+ Typical use: +
+
+
+ Get rid of HTML and JavaScript annoyances, banner + advertisements (by size), do fun text replacements, add + personalized effects, etc. +
+
+
+ Effect: +
+
+
+ All instances of text-based type, most notably HTML and + JavaScript, to which this action applies, can be filtered + on-the-fly through the specified regular expression based + substitutions. (Note: as of version 3.0.3 plain text + documents are exempted from filtering, because web servers + often use the text/plain MIME type + for all files whose type they don't know.) +
+
+
+ Type: +
+
+
+ Multi-value. +
+
+
+ Parameter: +
+
+
+ The name of a content filter, as defined in the filter file. Filters can be defined + in one or more files as defined by the filterfile option in the + config file. default.filter is the collection of filters + supplied by the developers. Locally defined filters should + go in their own file, such as user.filter. +
+
+ When used in its negative form, and without parameters, + all + filtering is completely disabled. +
+
+
+ Notes: +
+
+
+ For your convenience, there are a number of pre-defined + filters available in the distribution filter file that you + can use. See the examples below for a list. +
+
+ Filtering requires buffering the page content, which may + appear to slow down page rendering since nothing is + displayed until all content has passed the filters. (The + total time until the page is completely rendered doesn't + change much, but it may be perceived as slower since the + page is not incrementally displayed.) This effect will be + more noticeable on slower connections. +
+
+ "Rolling your own" filters + requires a knowledge of "Regular Expressions" + and "HTML". This is very + powerful feature, and potentially very intrusive. Filters + should be used with caution, and where an equivalent "action" is not available. +
+
+ The amount of data that can be filtered is limited to the + buffer-limit option in + the main config file. The default + is 4096 KB (4 Megs). Once this limit is exceeded, the + buffered data, and all pending data, is passed through + unfiltered. +
+
+ Inappropriate MIME types, such as zipped files, are not + filtered at all. (Again, only text-based types except plain + text). Encrypted SSL data (from HTTPS servers) cannot be + filtered either, since this would violate the integrity of + the secure transaction. In some situations it might be + necessary to protect certain text, like source code, from + filtering by defining appropriate -filter exceptions. +
+
+ Compressed content can't be filtered either, but if Privoxy is compiled with zlib + support and a supported compression algorithm is used (gzip + or deflate), Privoxy can + first decompress the content and then filter it. +
+
+ If you use a Privoxy + version without zlib support, but want filtering to work on + as much documents as possible, even those that would + normally be sent compressed, you must use the prevent-compression + action in conjunction with filter. +
+
+ Content filtering can achieve some of the same effects as + the block action, i.e. it + can be used to block ads and banners. But the mechanism + works quite differently. One effective use, is to block ad + banners based on their size (see below), since many of + these seem to be somewhat standardized. +
+
+ Feedback with suggestions for + new or improved filters is particularly welcome! +
+
+ The below list has only the names and a one-line + description of each predefined filter. There are more verbose + explanations of what these filters do in the filter file chapter. +
+
+
+ Example usage (with filters from the distribution default.filter file). See the Predefined Filters + section for more explanation on each: +
+
+
+ +
+ + + + +
+
++filter{js-annoyances} # Get rid of particularly annoying JavaScript abuse. +
+
+ +
+ +
+ + + + +
+
++filter{js-events} # Kill JavaScript event bindings and timers (Radically destructive! Only for extra nasty sites). +
+
+ +
+ +
+ + + + +
+
++filter{html-annoyances} # Get rid of particularly annoying HTML abuse. +
+
+ +
+ +
+ + + + +
+
++filter{content-cookies} # Kill cookies that come in the HTML or JS content. +
+
+ +
+ +
+ + + + +
+
++filter{refresh-tags} # Kill automatic refresh tags if refresh time is larger than 9 seconds. +
+
+ +
+ +
+ + + + +
+
++filter{unsolicited-popups} # Disable only unsolicited pop-up windows. +
+
+ +
+ +
+ + + + +
+
++filter{all-popups} # Kill all popups in JavaScript and HTML. +
+
+ +
+ +
+ + + + +
+
++filter{img-reorder} # Reorder attributes in <img> tags to make the banners-by-* filters more effective. +
+
+ +
+ +
+ + + + +
+
++filter{banners-by-size} # Kill banners by size. +
+
+ +
+ +
+ + + + +
+
++filter{banners-by-link} # Kill banners by their links to known clicktrackers. +
+
+ +
+ +
+ + + + +
+
++filter{webbugs} # Squish WebBugs (1x1 invisible GIFs used for user tracking). +
+
+ +
+ +
+ + + + +
+
++filter{tiny-textforms} # Extend those tiny textareas up to 40x80 and kill the hard wrap. +
+
+ +
+ +
+ + + + +
+
++filter{jumping-windows} # Prevent windows from resizing and moving themselves. +
+
+ +
+ +
+ + + + +
+
++filter{frameset-borders} # Give frames a border and make them resizable. +
+
+ +
+ +
+ + + + +
+
++filter{iframes} # Removes all detected iframes. Should only be enabled for individual sites. +
+
+ +
+ +
+ + + + +
+
++filter{demoronizer} # Fix MS's non-standard use of standard charsets. +
+
+ +
+ +
+ + + + +
+
++filter{shockwave-flash} # Kill embedded Shockwave Flash objects. +
+
+ +
+ +
+ + + + +
+
++filter{quicktime-kioskmode} # Make Quicktime movies saveable. +
+
+ +
+ +
+ + + + +
+
++filter{fun} # Text replacements for subversive browsing fun! +
+
+ +
+ +
+ + + + +
+
++filter{crude-parental} # Crude parental filtering. Note that this filter doesn't work reliably. +
+
+ +
+ +
+ + + + +
+
++filter{ie-exploits} # Disable some known Internet Explorer bug exploits. +
+
+ +
+ +
+ + + + +
+
++filter{site-specifics} # Cure for site-specific problems. Don't apply generally! +
+
+ +
+ +
+ + + + +
+
++filter{no-ping} # Removes non-standard ping attributes in <a> and <area> tags. +
+
+ +
+ +
+ + + + +
+
++filter{google} # CSS-based block for Google text ads. Also removes a width limitation and the toolbar advertisement. +
+
+ +
+ +
+ + + + +
+
++filter{yahoo} # CSS-based block for Yahoo text ads. Also removes a width limitation. +
+
+ +
+ +
+ + + + +
+
++filter{msn} # CSS-based block for MSN text ads. Also removes tracking URLs and a width limitation. +
+
+ +
+ +
+ + + + +
+
++filter{blogspot} # Cleans up some Blogspot blogs. Read the fine print before using this. +
+
+
+
+
+
+
+
+ 8.5.17. force-text-mode +
+
+
+
+ Typical use: +
+
+
+ Force Privoxy to treat a + document as if it was in some kind of text format. +
+
+
+ Effect: +
+
+
+ Declares a document as text, even if the "Content-Type:" isn't detected as such. +
+
+
+ Type: +
+
+
+ Boolean. +
+
+
+ Parameter: +
+
+
+ N/A +
+
+
+ Notes: +
+
+
+ As explained above, Privoxy tries to only filter files + that are in some kind of text format. The same restrictions + apply to content-type-overwrite. + force-text-mode declares a + document as text, without looking at the "Content-Type:" first. +
+
+ + + + + + + +
+ Warning +
+
+ Think twice before activating this action. + Filtering binary data with regular expressions can + cause file damage. +
+
+
+
+
+ Example usage: +
+
+
+
+ + + + +
+
++force-text-mode + +
+
+
+
+
+
+
+
+ 8.5.18. forward-override +
+
+
+
+ Typical use: +
+
+
+ Change the forwarding settings based on User-Agent or + request origin +
+
+
+ Effect: +
+
+
+ Overrules the forward directives in the configuration file. +
+
+
+ Type: +
+
+
+ Parameterized. +
+
+
+ Parameter: +
+
+
+
+
+ "forward ." to use a direct + connection without any additional proxies. +
+
+
+
+ "forward 127.0.0.1:8123" to + use the HTTP proxy listening at 127.0.0.1 port 8123. +
+
+
+
+ "forward-socks4a 127.0.0.1:9050 + ." to use the socks4a proxy listening at + 127.0.0.1 port 9050. Replace "forward-socks4a" with "forward-socks4" to use a socks4 + connection (with local DNS resolution) instead, use + "forward-socks5" for socks5 + connections (with remote DNS resolution). +
+
+
+
+ "forward-socks4a 127.0.0.1:9050 + proxy.example.org:8000" to use the socks4a proxy + listening at 127.0.0.1 port 9050 to reach the HTTP + proxy listening at proxy.example.org port 8000. Replace + "forward-socks4a" with "forward-socks4" to use a socks4 + connection (with local DNS resolution) instead, use + "forward-socks5" for socks5 + connections (with remote DNS resolution). +
+
+
+
+ "forward-webserver + 127.0.0.1:80" to use the HTTP server listening + at 127.0.0.1 port 80 without adjusting the request + headers. +
+
+ This makes it more convenient to use Privoxy to make + existing websites available as onion services as well. +
+
+ Many websites serve content with hardcoded URLs and + can't be easily adjusted to change the domain based on + the one used by the client. +
+
+ Putting Privoxy between Tor and the webserver (or an + stunnel that forwards to the webserver) allows to + rewrite headers and content to make client and server + happy at the same time. +
+
+ Using Privoxy for webservers that are only reachable + through onion addresses and whose location is supposed + to be secret is not recommended and should not be + necessary anyway. +
+
+
+
+
+ Notes: +
+
+
+ This action takes parameters similar to the forward directives in the + configuration file, but without the URL pattern. It can be + used as replacement, but normally it's only used in cases + where matching based on the request URL isn't sufficient. +
+
+ + + + + + + +
+ Warning +
+
+ Please read the description for the forward directives + before using this action. Forwarding to the wrong + people will reduce your privacy and increase the + chances of man-in-the-middle attacks. +
+
+ If the ports are missing or invalid, default values + will be used. This might change in the future and + you shouldn't rely on it. Otherwise incorrect + syntax causes Privoxy to exit. Due to design + limitations, invalid parameter syntax isn't + detected until the action is used the first time. +
+
+ Use the show-url-info CGI page to verify that + your forward settings do what you thought the do. +
+
+
+
+
+ Example usage: +
+
+
+
+ + +
+
+# Use an ssh tunnel for requests previously tagged as +# "User-Agent: fetch libfetch/2.0" and make sure # resuming downloads continues to work. +# # This way you can continue to use Tor for your normal browsing, # without overloading the Tor network with your FreeBSD ports updates # or downloads of bigger files like ISOs. +# # Note that HTTP headers are easy to fake and therefore their # values are as (un)trustworthy as your clients and users. -{+forward-override{forward .} \ +{+forward-override{forward-socks5 10.0.0.2:2222 .} \ -hide-if-modified-since \ -overwrite-last-modified \ } TAG:^User-Agent: fetch libfetch/2\.0$ -
-
8.5.17. handle-as-empty-document
Typical use:
Mark URLs that should be replaced by empty documents if they get blocked
Effect:
This action alone doesn't do anything noticeable. It just marks URLs. - If the block action also applies, - the presence or absence of this mark decides whether an HTML "BLOCKED" - page, or an empty document will be sent to the client as a substitute for the blocked content. - The empty document isn't literally empty, but actually contains a single space. -
Type:
Boolean.
Parameter:
N/A -
Notes:
Some browsers complain about syntax errors if JavaScript documents - are blocked with Privoxy's - default HTML page; this option can be used to silence them. - And of course this action can also be used to eliminate the Privoxy - BLOCKED message in frames. -
The content type for the empty document can be specified with - content-type-overwrite{}, - but usually this isn't necessary. -
Example usage:
+ +
# Block all documents on example.org that end with ".js", -# but send an empty document instead of the usual HTML message. + +
+
+
+
+
+
+
+
+ 8.5.19. + handle-as-empty-document +
+
+
+
+ Typical use: +
+
+
+ Mark URLs that should be replaced by empty documents if they get + blocked +
+
+
+ Effect: +
+
+
+ This action alone doesn't do anything noticeable. It just + marks URLs. If the block action also + applies, the presence or absence of this mark + decides whether an HTML "BLOCKED" page, or an empty document will be + sent to the client as a substitute for the blocked content. + The empty document isn't literally empty, + but actually contains a single space. +
+
+
+ Type: +
+
+
+ Boolean. +
+
+
+ Parameter: +
+
+
+ N/A +
+
+
+ Notes: +
+
+
+ Some browsers complain about syntax errors if JavaScript + documents are blocked with Privoxy's default HTML page; this + option can be used to silence them. And of course this + action can also be used to eliminate the Privoxy BLOCKED message in frames. +
+
+ The content type for the empty document can be specified + with content-type-overwrite{}, + but usually this isn't necessary. +
+
+
+ Example usage: +
+
+
+
+ + +
+
+# Block all documents on example.org that end with ".js", +# but send an empty document instead of the usual HTML message. {+block{Blocked JavaScript} +handle-as-empty-document} example.org/.*\.js$ -
-
8.5.18. handle-as-image
Typical use:
Mark URLs as belonging to images (so they'll be replaced by images if they do get blocked, rather than HTML pages)
Effect:
This action alone doesn't do anything noticeable. It just marks URLs as images. - If the block action also applies, - the presence or absence of this mark decides whether an HTML "blocked" - page, or a replacement image (as determined by the set-image-blocker action) will be sent to the - client as a substitute for the blocked content. -
Type:
Boolean.
Parameter:
N/A -
Notes:
The below generic example section is actually part of default.action. - It marks all URLs with well-known image file name extensions as images and should - be left intact. -
Users will probably only want to use the handle-as-image action in conjunction with - block, to block sources of banners, whose URLs don't - reflect the file type, like in the second example section. -
Note that you cannot treat HTML pages as images in most cases. For instance, (in-line) ad - frames require an HTML page to be sent, or they won't display properly. - Forcing handle-as-image in this situation will not replace the - ad frame with an image, but lead to error messages. -
Example usage (sections):
+ +
# Generic image extensions: + +
+
+
+
+
+
+
+
+ 8.5.20. handle-as-image +
+
+
+
+ Typical use: +
+
+
+ Mark URLs as belonging to images (so they'll be replaced by + images if they + do get blocked, rather than HTML pages) +
+
+
+ Effect: +
+
+
+ This action alone doesn't do anything noticeable. It just + marks URLs as images. If the block action also + applies, the presence or absence of this mark + decides whether an HTML "blocked" page, or a replacement image (as + determined by the set-image-blocker + action) will be sent to the client as a substitute for the + blocked content. +
+
+
+ Type: +
+
+
+ Boolean. +
+
+
+ Parameter: +
+
+
+ N/A +
+
+
+ Notes: +
+
+
+ The below generic example section is actually part of default.action. It marks all URLs + with well-known image file name extensions as images and + should be left intact. +
+
+ Users will probably only want to use the handle-as-image + action in conjunction with block, to block sources + of banners, whose URLs don't reflect the file type, like in + the second example section. +
+
+ Note that you cannot treat HTML pages as images in most + cases. For instance, (in-line) ad frames require an HTML + page to be sent, or they won't display properly. Forcing + handle-as-image in this situation + will not replace the ad frame with an image, but lead to + error messages. +
+
+
+ Example usage (sections): +
+
+
+
+ + +
+
+# Generic image extensions: # {+handle-as-image} /.*\.(gif|jpg|jpeg|png|bmp|ico)$ @@ -4629,1108 +3701,949 @@ CLASS="SCREEN" # blocked as images: # {+block{Nasty banners.} +handle-as-image} -nasty-banner-server.example.com/junk.cgi\?output=trash
-
8.5.19. hide-accept-language
Typical use:
Pretend to use different language settings.
Effect:
Deletes or replaces the "Accept-Language:" HTTP header in client requests. -
Type:
Parameterized.
Parameter:
Keyword: "block", or any user defined value. -
Notes:
Faking the browser's language settings can be useful to make a - foreign User-Agent set with - hide-user-agent - more believable. -
However some sites with content in different languages check the - "Accept-Language:" to decide which one to take by default. - Sometimes it isn't possible to later switch to another language without - changing the "Accept-Language:" header first. -
Therefore it's a good idea to either only change the - "Accept-Language:" header to languages you understand, - or to languages that aren't wide spread. -
Before setting the "Accept-Language:" header - to a rare language, you should consider that it helps to - make your requests unique and thus easier to trace. - If you don't plan to change this header frequently, - you should stick to a common language. -
Example usage (section):
+ +
# Pretend to use Canadian language settings. +nasty-banner-server.example.com/junk.cgi\?output=trash +
+
+
+
+
+
+
+
+ 8.5.21. hide-accept-language +
+
+
+
+ Typical use: +
+
+
+ Pretend to use different language settings. +
+
+
+ Effect: +
+
+
+ Deletes or replaces the "Accept-Language:" HTTP header in client + requests. +
+
+
+ Type: +
+
+
+ Parameterized. +
+
+
+ Parameter: +
+
+
+ Keyword: "block", or any user + defined value. +
+
+
+ Notes: +
+
+
+ Faking the browser's language settings can be useful to + make a foreign User-Agent set with hide-user-agent + more believable. +
+
+ However some sites with content in different languages + check the "Accept-Language:" to + decide which one to take by default. Sometimes it isn't + possible to later switch to another language without + changing the "Accept-Language:" + header first. +
+
+ Therefore it's a good idea to either only change the "Accept-Language:" header to languages + you understand, or to languages that aren't wide spread. +
+
+ Before setting the "Accept-Language:" header to a rare + language, you should consider that it helps to make your + requests unique and thus easier to trace. If you don't plan + to change this header frequently, you should stick to a + common language. +
+
+
+ Example usage (section): +
+
+
+
+ + +
+
+# Pretend to use Canadian language settings. {+hide-accept-language{en-ca} \ +hide-user-agent{Mozilla/5.0 (X11; U; OpenBSD i386; en-CA; rv:1.8.0.4) Gecko/20060628 Firefox/1.5.0.4} \ } -/
-
8.5.20. hide-content-disposition
Typical use:
Prevent download menus for content you prefer to view inside the browser.
Effect:
Deletes or replaces the "Content-Disposition:" HTTP header set by some servers. -
Type:
Parameterized.
Parameter:
Keyword: "block", or any user defined value. -
Notes:
Some servers set the "Content-Disposition:" HTTP header for - documents they assume you want to save locally before viewing them. - The "Content-Disposition:" header contains the file name - the browser is supposed to use by default. -
In most browsers that understand this header, it makes it impossible to - just view the document, without downloading it first, - even if it's just a simple text file or an image. -
Removing the "Content-Disposition:" header helps - to prevent this annoyance, but some browsers additionally check the - "Content-Type:" header, before they decide if they can - display a document without saving it first. In these cases, you have - to change this header as well, before the browser stops displaying - download menus. -
It is also possible to change the server's file name suggestion - to another one, but in most cases it isn't worth the time to set - it up. -
This action will probably be removed in the future, - use server-header filters instead. -
Example usage:
+ +
# Disarm the download link in Sourceforge's patch tracker +/ +
+
+
+
+
+
+
+
+ 8.5.22. + hide-content-disposition +
+
+
+
+ Typical use: +
+
+
+ Prevent download menus for content you prefer to view + inside the browser. +
+
+
+ Effect: +
+
+
+ Deletes or replaces the "Content-Disposition:" HTTP header set by + some servers. +
+
+
+ Type: +
+
+
+ Parameterized. +
+
+
+ Parameter: +
+
+
+ Keyword: "block", or any user + defined value. +
+
+
+ Notes: +
+
+
+ Some servers set the "Content-Disposition:" HTTP header for + documents they assume you want to save locally before + viewing them. The "Content-Disposition:" header contains the + file name the browser is supposed to use by default. +
+
+ In most browsers that understand this header, it makes it + impossible to just view the document, without + downloading it first, even if it's just a simple text file + or an image. +
+
+ Removing the "Content-Disposition:" header helps to + prevent this annoyance, but some browsers additionally + check the "Content-Type:" + header, before they decide if they can display a document + without saving it first. In these cases, you have to change + this header as well, before the browser stops displaying + download menus. +
+
+ It is also possible to change the server's file name + suggestion to another one, but in most cases it isn't worth + the time to set it up. +
+
+ This action will probably be removed in the future, use + server-header filters instead. +
+
+
+ Example usage: +
+
+
+
+ + +
+
+# Disarm the download link in Sourceforge's patch tracker { -filter \ +content-type-overwrite{text/plain}\ +hide-content-disposition{block} } - .sourceforge.net/tracker/download\.php
-
8.5.21. hide-if-modified-since
Typical use:
Prevent yet another way to track the user's steps between sessions.
Effect:
Deletes the "If-Modified-Since:" HTTP client header or modifies its value. -
Type:
Parameterized.
Parameter:
Keyword: "block", or a user defined value that specifies a range of hours. -
Notes:
Removing this header is useful for filter testing, where you want to force a real - reload instead of getting status code "304", which would cause the - browser to use a cached copy of the page. -
Instead of removing the header, hide-if-modified-since can - also add or subtract a random amount of time to/from the header's value. - You specify a range of minutes where the random factor should be chosen from and - Privoxy does the rest. A negative value means - subtracting, a positive value adding. -
Randomizing the value of the "If-Modified-Since:" makes - it less likely that the server can use the time as a cookie replacement, - but you will run into caching problems if the random range is too high. -
It is a good idea to only use a small negative value and let - overwrite-last-modified - handle the greater changes. -
It is also recommended to use this action together with - crunch-if-none-match, - otherwise it's more or less pointless. -
Example usage (section):
+ +
# Let the browser revalidate but make tracking based on the time less likely. + .sourceforge.net/tracker/download\.php +
+
+
+
+
+
+
+
+ 8.5.23. + hide-if-modified-since +
+
+
+
+ Typical use: +
+
+
+ Prevent yet another way to track the user's steps between + sessions. +
+
+
+ Effect: +
+
+
+ Deletes the "If-Modified-Since:" + HTTP client header or modifies its value. +
+
+
+ Type: +
+
+
+ Parameterized. +
+
+
+ Parameter: +
+
+
+ Keyword: "block", or a user + defined value that specifies a range of hours. +
+
+
+ Notes: +
+
+
+ Removing this header is useful for filter testing, where + you want to force a real reload instead of getting status + code "304", which would cause + the browser to use a cached copy of the page. +
+
+ Instead of removing the header, hide-if-modified-since can also add or + subtract a random amount of time to/from the header's + value. You specify a range of minutes where the random + factor should be chosen from and Privoxy does the rest. A negative + value means subtracting, a positive value adding. +
+
+ Randomizing the value of the "If-Modified-Since:" makes it less likely + that the server can use the time as a cookie replacement, + but you will run into caching problems if the random range + is too high. +
+
+ It is a good idea to only use a small negative value and + let overwrite-last-modified + handle the greater changes. +
+
+ It is also recommended to use this action together with crunch-if-none-match, + otherwise it's more or less pointless. +
+
+
+ Example usage (section): +
+
+
+
+ + +
+
+# Let the browser revalidate but make tracking based on the time less likely. {+hide-if-modified-since{-60} \ +overwrite-last-modified{randomize} \ +crunch-if-none-match} -/
-
8.5.22. hide-forwarded-for-headers
Typical use:
Improve privacy by not forwarding the source of the request in the HTTP headers.
Effect:
Deletes any existing "X-Forwarded-for:" HTTP header from client requests. -
Type:
Boolean.
Parameter:
N/A -
Notes:
It is safe and recommended to leave this on. -
Example usage:

+hide-forwarded-for-headers
-
8.5.23. hide-from-header
Typical use:
Keep your (old and ill) browser from telling web servers your email address
Effect:
Deletes any existing "From:" HTTP header, or replaces it with the - specified string. -
Type:
Parameterized.
Parameter:
Keyword: "block", or any user defined value. -
Notes:
The keyword "block" will completely remove the header - (not to be confused with the block - action). -
Alternately, you can specify any value you prefer to be sent to the web - server. If you do, it is a matter of fairness not to use any address that - is actually used by a real person. -
This action is rarely needed, as modern web browsers don't send - "From:" headers anymore. -
Example usage:

+hide-from-header{block}
or -
+hide-from-header{spam-me-senseless@sittingduck.example.com}
-
8.5.24. hide-referrer
Typical use:
Conceal which link you followed to get to a particular site
Effect:
Deletes the "Referer:" (sic) HTTP header from the client request, - or replaces it with a forged one. -
Type:
Parameterized.
Parameter:
"conditional-block" to delete the header completely if the host has changed.
"conditional-forge" to forge the header if the host has changed.
"block" to delete the header unconditionally.
"forge" to pretend to be coming from the homepage of the server we are talking to.
Any other string to set a user defined referrer.
Notes:
conditional-block is the only parameter, - that isn't easily detected in the server's log file. If it blocks the - referrer, the request will look like the visitor used a bookmark or - typed in the address directly. -
Leaving the referrer unmodified for requests on the same host - allows the server owner to see the visitor's "click path", - but in most cases she could also get that information by comparing - other parts of the log file: for example the User-Agent if it isn't - a very common one, or the user's IP address if it doesn't change between - different requests. -
Always blocking the referrer, or using a custom one, can lead to - failures on servers that check the referrer before they answer any - requests, in an attempt to prevent their content from being - embedded or linked to elsewhere. -
Both conditional-block and forge - will work with referrer checks, as long as content and valid referring page - are on the same host. Most of the time that's the case. -
- hide-referer is an alternate spelling of - hide-referrer and the two can be can be freely - substituted with each other. ("referrer" is the - correct English spelling, however the HTTP specification has a bug - it - requires it to be spelled as "referer".) -
Example usage:

+hide-referrer{forge}
or -
+hide-referrer{http://www.yahoo.com/}
-
8.5.25. hide-user-agent
Typical use:
Try to conceal your type of browser and client operating system
Effect:
Replaces the value of the "User-Agent:" HTTP header - in client requests with the specified value. -
Type:
Parameterized.
Parameter:
Any user-defined string. -
Notes:
Warning
This can lead to problems on web sites that depend on looking at this header in - order to customize their content for different browsers (which, by the - way, is NOT the right thing to do: good web sites - work browser-independently). -
Using this action in multi-user setups or wherever different types of - browsers will access the same Privoxy is - not recommended. In single-user, single-browser - setups, you might use it to delete your OS version information from - the headers, because it is an invitation to exploit known bugs for your - OS. It is also occasionally useful to forge this in order to access - sites that won't let you in otherwise (though there may be a good - reason in some cases). Example of this: some MSN sites will not - let Mozilla enter, yet forging to a - Netscape 6.1 user-agent works just fine. - (Must be just a silly MS goof, I'm sure :-). -
More information on known user-agent strings can be found at - http://www.user-agents.org/ - and - http://en.wikipedia.org/wiki/User_agent. -
Example usage:

+hide-user-agent{Netscape 6.1 (X11; I; Linux 2.4.18 i686)}
-
8.5.26. limit-connect
Typical use:
Prevent abuse of Privoxy as a TCP proxy relay or disable SSL for untrusted sites
Effect:
Specifies to which ports HTTP CONNECT requests are allowable. -
Type:
Parameterized.
Parameter:
A comma-separated list of ports or port ranges (the latter using dashes, with the minimum - defaulting to 0 and the maximum to 65K). -
Notes:
By default, i.e. if no limit-connect action applies, - Privoxy allows HTTP CONNECT requests to all - ports. Use limit-connect if fine-grained control - is desired for some or all destinations. -
The CONNECT methods exists in HTTP to allow access to secure websites - ("https://" URLs) through proxies. It works very simply: - the proxy connects to the server on the specified port, and then - short-circuits its connections to the client and to the remote server. - This means CONNECT-enabled proxies can be used as TCP relays very easily. -
Privoxy relays HTTPS traffic without seeing - the decoded content. Websites can leverage this limitation to circumvent Privoxy's - filters. By specifying an invalid port range you can disable HTTPS entirely. -
Example usages:
+ +
+limit-connect{443} # Port 443 is OK. +/ +
+
+
+
+
+
+
+
+ 8.5.24. hide-from-header +
+
+
+
+ Typical use: +
+
+
+ Keep your (old and ill) browser from telling web servers + your email address +
+
+
+ Effect: +
+
+
+ Deletes any existing "From:" + HTTP header, or replaces it with the specified string. +
+
+
+ Type: +
+
+
+ Parameterized. +
+
+
+ Parameter: +
+
+
+ Keyword: "block", or any user + defined value. +
+
+
+ Notes: +
+
+
+ The keyword "block" will + completely remove the header (not to be confused with the + block action). +
+
+ Alternately, you can specify any value you prefer to be + sent to the web server. If you do, it is a matter of + fairness not to use any address that is actually used by a + real person. +
+
+ This action is rarely needed, as modern web browsers don't + send "From:" headers anymore. +
+
+
+ Example usage: +
+
+
+
+ + + + +
+
++hide-from-header{block} +
+
+ or + + + + +
+
++hide-from-header{spam-me-senseless@sittingduck.example.com} +
+
+
+
+
+
+
+
+ 8.5.25. hide-referrer +
+ +
+
+
+ Typical use: +
+
+
+ Conceal which link you followed to get to a particular site +
+
+
+ Effect: +
+
+
+ Deletes the "Referer:" (sic) + HTTP header from the client request, or replaces it with a + forged one. +
+
+
+ Type: +
+
+
+ Parameterized. +
+
+
+ Parameter: +
+
+
+
+
+ "conditional-block" to + delete the header completely if the host has changed. +
+
+
+
+ "conditional-forge" to forge + the header if the host has changed. +
+
+
+
+ "block" to delete the header + unconditionally. +
+
+
+
+ "forge" to pretend to be + coming from the homepage of the server we are talking + to. +
+
+
+
+ Any other string to set a user defined referrer. +
+
+
+
+
+ Notes: +
+
+
+ conditional-block is the only + parameter, that isn't easily detected in the server's log + file. If it blocks the referrer, the request will look like + the visitor used a bookmark or typed in the address + directly. +
+
+ Leaving the referrer unmodified for requests on the same + host allows the server owner to see the visitor's "click path", but in most cases she + could also get that information by comparing other parts of + the log file: for example the User-Agent if it isn't a very + common one, or the user's IP address if it doesn't change + between different requests. +
+
+ Always blocking the referrer, or using a custom one, can + lead to failures on servers that check the referrer before + they answer any requests, in an attempt to prevent their + content from being embedded or linked to elsewhere. +
+
+ Both conditional-block and forge will work with referrer checks, + as long as content and valid referring page are on the same + host. Most of the time that's the case. +
+
+ hide-referer is an alternate + spelling of hide-referrer and the + two can be can be freely substituted with each other. + ("referrer" is the correct + English spelling, however the HTTP specification has a bug + - it requires it to be spelled as "referer".) +
+
+
+ Example usage: +
+
+
+
+ + + + +
+
++hide-referrer{forge} +
+
+ or + + + + +
+
++hide-referrer{http://www.yahoo.com/} +
+
+
+
+
+
+
+
+ 8.5.26. hide-user-agent +
+
+
+
+ Typical use: +
+
+
+ Try to conceal your type of browser and client operating + system +
+
+
+ Effect: +
+
+
+ Replaces the value of the "User-Agent:" HTTP header in client requests + with the specified value. +
+
+
+ Type: +
+
+
+ Parameterized. +
+
+
+ Parameter: +
+
+
+ Any user-defined string. +
+
+
+ Notes: +
+
+
+ + + + + + + +
+ Warning +
+
+ This can lead to problems on web sites that depend + on looking at this header in order to customize + their content for different browsers (which, by the + way, is NOT the right thing to do: + good web sites work browser-independently). +
+
+
+
+ Using this action in multi-user setups or wherever + different types of browsers will access the same Privoxy is not recommended. + In single-user, single-browser setups, you might use it to + delete your OS version information from the headers, + because it is an invitation to exploit known bugs for your + OS. It is also occasionally useful to forge this in order + to access sites that won't let you in otherwise (though + there may be a good reason in some cases). +
+
+ More information on known user-agent strings can be found + at http://www.user-agents.org/ and http://en.wikipedia.org/wiki/User_agent. +
+
+
+ Example usage: +
+
+
+
+ + + + +
+
++hide-user-agent{Netscape 6.1 (X11; I; Linux 2.4.18 i686)} +
+
+
+
+
+
+
+
+ 8.5.27. limit-connect +
+
+
+
+ Typical use: +
+
+
+ Prevent abuse of Privoxy + as a TCP proxy relay or disable SSL for untrusted sites +
+
+
+ Effect: +
+
+
+ Specifies to which ports HTTP CONNECT requests are + allowable. +
+
+
+ Type: +
+
+
+ Parameterized. +
+
+
+ Parameter: +
+
+
+ A comma-separated list of ports or port ranges (the latter + using dashes, with the minimum defaulting to 0 and the + maximum to 65K). +
+
+
+ Notes: +
+
+
+ By default, i.e. if no limit-connect action applies, Privoxy allows HTTP CONNECT requests + to all ports. Use limit-connect if + fine-grained control is desired for some or all + destinations. +
+
+ The CONNECT methods exists in HTTP to allow access to + secure websites ("https://" + URLs) through proxies. It works very simply: the proxy + connects to the server on the specified port, and then + short-circuits its connections to the client and to the + remote server. This means CONNECT-enabled proxies can be + used as TCP relays very easily. +
+
+ Privoxy relays HTTPS + traffic without seeing the decoded content. Websites can + leverage this limitation to circumvent Privoxy's filters. By specifying an + invalid port range you can disable HTTPS entirely. +
+
+
+ Example usages: +
+
+
+
+ + +
+
++limit-connect{443} # Port 443 is OK. +limit-connect{80,443} # Ports 80 and 443 are OK. +limit-connect{-3, 7, 20-100, 500-} # Ports less than 3, 7, 20 to 100 and above 500 are OK. +limit-connect{-} # All ports are OK -+limit-connect{,} # No HTTPS/SSL traffic is allowed
-
8.5.27. prevent-compression
Typical use:
Ensure that servers send the content uncompressed, so it can be - passed through filters. -
Effect:
Removes the Accept-Encoding header which can be used to ask for compressed transfer. -
Type:
Boolean.
Parameter:
N/A -
Notes:
More and more websites send their content compressed by default, which - is generally a good idea and saves bandwidth. But the filter and - deanimate-gifs - actions need access to the uncompressed data. -
When compiled with zlib support (available since Privoxy 3.0.7), content that should be - filtered is decompressed on-the-fly and you don't have to worry about this action. - If you are using an older Privoxy version, or one that hasn't been compiled with zlib - support, this action can be used to convince the server to send the content uncompressed. -
Most text-based instances compress very well, the size is seldom decreased by less than 50%, - for markup-heavy instances like news feeds saving more than 90% of the original size isn't - unusual. -
Not using compression will therefore slow down the transfer, and you should only - enable this action if you really need it. As of Privoxy 3.0.7 it's disabled in all - predefined action settings. -
Note that some (rare) ill-configured sites don't handle requests for uncompressed - documents correctly. Broken PHP applications tend to send an empty document body, - some IIS versions only send the beginning of the content. If you enable - prevent-compression per default, you might want to add - exceptions for those sites. See the example for how to do that. -
Example usage (sections):
+ +
# Selectively turn off compression, and enable a filter ++limit-connect{,} # No HTTPS/SSL traffic is allowed +
+
+
+
+
+
+
+
+ 8.5.28. limit-cookie-lifetime +
+
+
+
+ Typical use: +
+
+
+ Limit the lifetime of HTTP cookies to a couple of minutes + or hours. +
+
+
+ Effect: +
+
+
+ Overwrites the expires field in Set-Cookie server headers + if it's above the specified limit. +
+
+
+ Type: +
+
+
+ Parameterized. +
+
+
+ Parameter: +
+
+
+ The lifetime limit in minutes, or 0. +
+
+
+ Notes: +
+
+
+ This action reduces the lifetime of HTTP cookies coming + from the server to the specified number of minutes, + starting from the time the cookie passes Privoxy. +
+
+ Cookies with a lifetime below the limit are not modified. + The lifetime of session cookies is set to the specified + limit. +
+
+ The effect of this action depends on the server. +
+
+ In case of servers which refresh their cookies with each + response (or at least frequently), the lifetime limit set + by this action is updated as well. Thus, a session + associated with the cookie continues to work with this + action enabled, as long as a new request is made before the + last limit set is reached. +
+
+ However, some servers send their cookies once, with a + lifetime of several years (the year 2037 is a popular + choice), and do not refresh them until a certain event in + the future, for example the user logging out. In this case + this action may limit the absolute lifetime of the session, + even if requests are made frequently. +
+
+ If the parameter is "0", this + action behaves like session-cookies-only. +
+
+
+ Example usages: +
+
+
+
+ + + + +
+
++limit-cookie-lifetime{60} + +
+
+
+
+
+
+
+
+ 8.5.29. prevent-compression +
+
+
+
+ Typical use: +
+
+
+ Ensure that servers send the content uncompressed, so it + can be passed through filters. +
+
+
+ Effect: +
+
+
+ Removes the Accept-Encoding header which can be used to ask + for compressed transfer. +
+
+
+ Type: +
+
+
+ Boolean. +
+
+
+ Parameter: +
+
+
+ N/A +
+
+
+ Notes: +
+
+
+ More and more websites send their content compressed by + default, which is generally a good idea and saves + bandwidth. But the filter and deanimate-gifs + actions need access to the uncompressed data. +
+
+ When compiled with zlib support (available since Privoxy 3.0.7), content that + should be filtered is decompressed on-the-fly and you don't + have to worry about this action. If you are using an older + Privoxy version, or one + that hasn't been compiled with zlib support, this action + can be used to convince the server to send the content + uncompressed. +
+
+ Most text-based instances compress very well, the size is + seldom decreased by less than 50%, for markup-heavy + instances like news feeds saving more than 90% of the + original size isn't unusual. +
+
+ Not using compression will therefore slow down the + transfer, and you should only enable this action if you + really need it. As of Privoxy 3.0.7 it's disabled in all + predefined action settings. +
+
+ Note that some (rare) ill-configured sites don't handle + requests for uncompressed documents correctly. Broken PHP + applications tend to send an empty document body, some IIS + versions only send the beginning of the content. If you + enable prevent-compression per + default, you might want to add exceptions for those sites. + See the example for how to do that. +
+
+
+ Example usage (sections): +
+
+
+
+ + +
+
+# Selectively turn off compression, and enable a filter # { +filter{tiny-textforms} +prevent-compression } # Match only these sites @@ -5746,1076 +4659,803 @@ CLASS="SCREEN" # Then maybe make exceptions for broken sites: # { -prevent-compression } -.compusa.com/
-
8.5.28. overwrite-last-modified
Typical use:
Prevent yet another way to track the user's steps between sessions.
Effect:
Deletes the "Last-Modified:" HTTP server header or modifies its value. -
Type:
Parameterized.
Parameter:
One of the keywords: "block", "reset-to-request-time" - and "randomize" -
Notes:
Removing the "Last-Modified:" header is useful for filter - testing, where you want to force a real reload instead of getting status - code "304", which would cause the browser to reuse the old - version of the page. -
The "randomize" option overwrites the value of the - "Last-Modified:" header with a randomly chosen time - between the original value and the current time. In theory the server - could send each document with a different "Last-Modified:" - header to track visits without using cookies. "Randomize" - makes it impossible and the browser can still revalidate cached documents. -
"reset-to-request-time" overwrites the value of the - "Last-Modified:" header with the current time. You could use - this option together with - hided-if-modified-since - to further customize your random range. -
The preferred parameter here is "randomize". It is safe - to use, as long as the time settings are more or less correct. - If the server sets the "Last-Modified:" header to the time - of the request, the random range becomes zero and the value stays the same. - Therefore you should later randomize it a second time with - hided-if-modified-since, - just to be sure. -
It is also recommended to use this action together with - crunch-if-none-match. -
Example usage:
+ +
# Let the browser revalidate without being tracked across sessions +.compusa.com/ +
+
+
+
+
+
+
+
+ 8.5.30. + overwrite-last-modified +
+
+
+
+ Typical use: +
+
+
+ Prevent yet another way to track the user's steps between + sessions. +
+
+
+ Effect: +
+
+
+ Deletes the "Last-Modified:" + HTTP server header or modifies its value. +
+
+
+ Type: +
+
+
+ Parameterized. +
+
+
+ Parameter: +
+
+
+ One of the keywords: "block", + "reset-to-request-time" and + "randomize" +
+
+
+ Notes: +
+
+
+ Removing the "Last-Modified:" + header is useful for filter testing, where you want to + force a real reload instead of getting status code "304", which would cause the browser + to reuse the old version of the page. +
+
+ The "randomize" option + overwrites the value of the "Last-Modified:" header with a randomly + chosen time between the original value and the current + time. In theory the server could send each document with a + different "Last-Modified:" + header to track visits without using cookies. "Randomize" makes it impossible and the + browser can still revalidate cached documents. +
+
+ "reset-to-request-time" + overwrites the value of the "Last-Modified:" header with the current + time. You could use this option together with hide-if-modified-since + to further customize your random range. +
+
+ The preferred parameter here is "randomize". It is safe to use, as long as + the time settings are more or less correct. If the server + sets the "Last-Modified:" header + to the time of the request, the random range becomes zero + and the value stays the same. Therefore you should later + randomize it a second time with hided-if-modified-since, + just to be sure. +
+
+ It is also recommended to use this action together with crunch-if-none-match. +
+
+
+ Example usage: +
+
+
+
+ + +
+
+# Let the browser revalidate without being tracked across sessions { +hide-if-modified-since{-60} \ +overwrite-last-modified{randomize} \ +crunch-if-none-match} -/
-
8.5.29. redirect
Typical use:
Redirect requests to other sites. -
Effect:
Convinces the browser that the requested document has been moved - to another location and the browser should get it from there. -
Type:
Parameterized
Parameter:
An absolute URL or a single pcrs command. -
Notes:
Requests to which this action applies are answered with a - HTTP redirect to URLs of your choosing. The new URL is - either provided as parameter, or derived by applying a - single pcrs command to the original URL. -
This action will be ignored if you use it together with - block. - It can be combined with - fast-redirects{check-decoded-url} - to redirect to a decoded version of a rewritten URL. -
Use this action carefully, make sure not to create redirection loops - and be aware that using your own redirects might make it - possible to fingerprint your requests. -
In case of problems with your redirects, or simply to watch - them working, enable debug 128. -
Example usages:
+ +
# Replace example.com's style sheet with another one +/ +
+
+
+
+
+
+
+
+ 8.5.31. redirect +
+
+
+
+ Typical use: +
+
+
+ Redirect requests to other sites. +
+
+
+ Effect: +
+
+
+ Convinces the browser that the requested document has been + moved to another location and the browser should get it + from there. +
+
+
+ Type: +
+
+
+ Parameterized +
+
+
+ Parameter: +
+
+
+ An absolute URL or a single pcrs command. +
+
+
+ Notes: +
+
+
+ Requests to which this action applies are answered with a + HTTP redirect to URLs of your choosing. The new URL is + either provided as parameter, or derived by applying a + single pcrs command to the original URL. +
+
+ The syntax for pcrs commands is documented in the filter file section. +
+
+ Requests can't be blocked and redirected at the same time, + applying this action together with block is a + configuration error. Currently the request is blocked and + an error message logged, the behavior may change in the + future and result in Privoxy rejecting the action file. +
+
+ This action can be combined with fast-redirects{check-decoded-url} + to redirect to a decoded version of a rewritten URL. +
+
+ Use this action carefully, make sure not to create + redirection loops and be aware that using your own + redirects might make it possible to fingerprint your + requests. +
+
+ In case of problems with your redirects, or simply to watch + them working, enable debug + 128. +
+
+
+ Example usages: +
+
+
+
+ + +
+
+# Replace example.com's style sheet with another one { +redirect{http://localhost/css-replacements/example.com.css} } example.com/stylesheet\.css # Create a short, easy to remember nickname for a favorite site -# (relies on the browser accept and forward invalid URLs to Privoxy) -{ +redirect{http://www.privoxy.org/user-manual/actions-file.html} } +# (relies on the browser to accept and forward invalid URLs to Privoxy) +{ +redirect{https://www.privoxy.org/user-manual/actions-file.html} } a # Always use the expanded view for Undeadly.org articles # (Note the $ at the end of the URL pattern to make sure # the request for the rewritten URL isn't redirected as well) -{+redirect{s@$@&mode=expanded@}} -undeadly.org/cgi\?action=article&sid=\d*$ +{+redirect{s@$@&mode=expanded@}} +undeadly.org/cgi\?action=article&sid=\d*$ # Redirect Google search requests to MSN -{+redirect{s@^http://[^/]*/search\?q=([^&]*).*@http://search.msn.com/results.aspx?q=$1@}} +{+redirect{s@^http://[^/]*/search\?q=([^&]*).*@http://search.msn.com/results.aspx?q=$1@}} .google.com/search # Redirect MSN search requests to Yahoo -{+redirect{s@^http://[^/]*/results\.aspx\?q=([^&]*).*@http://search.yahoo.com/search?p=$1@}} +{+redirect{s@^http://[^/]*/results\.aspx\?q=([^&]*).*@http://search.yahoo.com/search?p=$1@}} search.msn.com//results\.aspx\?q= +# Redirect http://example.com/&bla=fasel&toChange=foo (and any other value but "bar") +# to http://example.com/&bla=fasel&toChange=bar +# +# The URL pattern makes sure that the following request isn't redirected again. +{+redirect{s@toChange=[^&]+@toChange=bar@}} +example.com/.*toChange=(?!bar) + +# Add a shortcut to look up illumos bugs +{+redirect{s@^http://i([0-9]+)/.*@https://www.illumos.org/issues/$1@}} +# Redirected URL = http://i4974/ +# Redirect Destination = https://www.illumos.org/issues/4974 +i[0-9][0-9][0-9][0-9]*/ + # Redirect remote requests for this manual # to the local version delivered by Privoxy {+redirect{s@^http://www@http://config@}} -www.privoxy.org/user-manual/
-
8.5.30. server-header-filter
Typical use:
Rewrite or remove single server headers. -
Effect:
All server headers to which this action applies are filtered on-the-fly - through the specified regular expression based substitutions. -
Type:
Parameterized.
Parameter:
The name of a server-header filter, as defined in one of the - filter files. -
Notes:
Server-header filters are applied to each header on its own, not to - all at once. This makes it easier to diagnose problems, but on the downside - you can't write filters that only change header x if header y's value is z. - You can do that by using tags though. -
Server-header filters are executed after the other header actions have finished - and use their output as input. -
Please refer to the filter file chapter - to learn which server-header filters are available by default, and how to - create your own. -
Example usage (section):
+ +
{+server-header-filter{html-to-xml}} +www.privoxy.org/user-manual/ +
+
+
+
+
+
+
+
+ 8.5.32. server-header-filter +
+
+
+
+ Typical use: +
+
+
+ Rewrite or remove single server headers. +
+
+
+ Effect: +
+
+
+ All server headers to which this action applies are + filtered on-the-fly through the specified regular + expression based substitutions. +
+
+
+ Type: +
+
+
+ Multi-value. +
+
+
+ Parameter: +
+
+
+ The name of a server-header filter, as defined in one of + the filter files. +
+
+
+ Notes: +
+
+
+ Server-header filters are applied to each header on its + own, not to all at once. This makes it easier to diagnose + problems, but on the downside you can't write filters that + only change header x if header y's value is z. You can do + that by using tags though. +
+
+ Server-header filters are executed after the other header + actions have finished and use their output as input. +
+
+ Please refer to the filter file + chapter to learn which server-header filters are + available by default, and how to create your own. +
+
+
+ Example usage (section): +
+
+
+
+ + +
+
+{+server-header-filter{html-to-xml}} example.org/xml-instance-that-is-delivered-as-html {+server-header-filter{xml-to-html}} example.org/instance-that-is-delivered-as-xml-but-is-not -
-
8.5.31. server-header-tagger
Typical use:
Enable or disable filters based on the Content-Type header. -
Effect:
Server headers to which this action applies are filtered on-the-fly through - the specified regular expression based substitutions, the result is used as - tag. -
Type:
Parameterized.
Parameter:
The name of a server-header tagger, as defined in one of the - filter files. -
Notes:
Server-header taggers are applied to each header on its own, - and as the header isn't modified, each tagger "sees" - the original. -
Server-header taggers are executed before all other header actions - that modify server headers. Their tags can be used to control - all of the other server-header actions, the content filters - and the crunch actions (redirect - and block). -
Obviously crunching based on tags created by server-header taggers - doesn't prevent the request from showing up in the server's log file. -
Example usage (section):
+ +
# Tag every request with the content type declared by the server + +
+
+
+
+
+
+
+
+ 8.5.33. server-header-tagger +
+
+
+
+ Typical use: +
+
+
+ Enable or disable filters based on the Content-Type header. +
+
+
+ Effect: +
+
+
+ Server headers to which this action applies are filtered + on-the-fly through the specified regular expression based + substitutions, the result is used as tag. +
+
+
+ Type: +
+
+
+ Multi-value. +
+
+
+ Parameter: +
+
+
+ The name of a server-header tagger, as defined in one of + the filter files. +
+
+
+ Notes: +
+
+
+ Server-header taggers are applied to each header on its + own, and as the header isn't modified, each tagger "sees" the original. +
+
+ Server-header taggers are executed before all other header + actions that modify server headers. Their tags can be used + to control all of the other server-header actions, the + content filters and the crunch actions (redirect and block). +
+
+ Obviously crunching based on tags created by server-header + taggers doesn't prevent the request from showing up in the + server's log file. +
+
+
+ Example usage (section): +
+
+
+
+ + +
+
+# Tag every request with the content type declared by the server {+server-header-tagger{content-type}} / -
-
8.5.32. session-cookies-only
Typical use:
Allow only temporary "session" cookies (for the current - browser session only). -
Effect:
Deletes the "expires" field from "Set-Cookie:" - server headers. Most browsers will not store such cookies permanently and - forget them in between sessions. -
Type:
Boolean.
Parameter:
N/A -
Notes:
This is less strict than crunch-incoming-cookies / - crunch-outgoing-cookies and allows you to browse - websites that insist or rely on setting cookies, without compromising your privacy too badly. -
Most browsers will not permanently store cookies that have been processed by - session-cookies-only and will forget about them between sessions. - This makes profiling cookies useless, but won't break sites which require cookies so - that you can log in for transactions. This is generally turned on for all - sites, and is the recommended setting. -
It makes no sense at all to use session-cookies-only - together with crunch-incoming-cookies or - crunch-outgoing-cookies. If you do, cookies - will be plainly killed. -
Note that it is up to the browser how it handles such cookies without an "expires" - field. If you use an exotic browser, you might want to try it out to be sure. -
This setting also has no effect on cookies that may have been stored - previously by the browser before starting Privoxy. - These would have to be removed manually. -
Privoxy also uses - the content-cookies filter - to block some types of cookies. Content cookies are not effected by - session-cookies-only. -
Example usage:

+session-cookies-only
-
8.5.33. set-image-blocker
Typical use:
Choose the replacement for blocked images
Effect:
This action alone doesn't do anything noticeable. If both - block and handle-as-image also - apply, i.e. if the request is to be blocked as an image, - then the parameter of this action decides what will be - sent as a replacement. -
Type:
Parameterized.
Parameter:
"pattern" to send a built-in checkerboard pattern image. The image is visually - decent, scales very well, and makes it obvious where banners were busted. -
"blank" to send a built-in transparent image. This makes banners disappear - completely, but makes it hard to detect where Privoxy has blocked - images on a given page and complicates troubleshooting if Privoxy - has blocked innocent images, like navigation icons. -
"target-url" to - send a redirect to target-url. You can redirect - to any image anywhere, even in your local filesystem via "file:///" URL. - (But note that not all browsers support redirecting to a local file system). -
A good application of redirects is to use special Privoxy-built-in - URLs, which send the built-in images, as target-url. - This has the same visual effect as specifying "blank" or "pattern" in - the first place, but enables your browser to cache the replacement image, instead of requesting - it over and over again. -
Notes:
The URLs for the built-in images are "http://config.privoxy.org/send-banner?type=type", where type is - either "blank" or "pattern". -
There is a third (advanced) type, called "auto". It is NOT to be - used in set-image-blocker, but meant for use from filters. - Auto will select the type of image that would have applied to the referring page, had it been an image. -
Example usage:
Built-in pattern: -

+set-image-blocker{pattern}
-
Redirect to the BSD daemon: -

+set-image-blocker{http://www.freebsd.org/gifs/dae_up3.gif}
-
Redirect to the built-in pattern for better caching: -

+set-image-blocker{http://config.privoxy.org/send-banner?type=pattern}
-
8.5.34. Summary
Note that many of these actions have the potential to cause a page to - misbehave, possibly even not to display at all. There are many ways - a site designer may choose to design his site, and what HTTP header - content, and other criteria, he may depend on. There is no way to have hard - and fast rules for all sites. See the Appendix for a brief example on troubleshooting - actions.
8.6. Aliases
Custom "actions", known to Privoxy - as "aliases", can be defined by combining other actions. - These can in turn be invoked just like the built-in actions. - Currently, an alias name can contain any character except space, tab, - "=", - "{" and "}", but we strongly - recommend that you only use "a" to "z", - "0" to "9", "+", and "-". - Alias names are not case sensitive, and are not required to start with a - "+" or "-" sign, since they are merely textually - expanded.
Aliases can be used throughout the actions file, but they must be - defined in a special section at the top of the file! - And there can only be one such section per actions file. Each actions file may - have its own alias section, and the aliases defined in it are only visible - within that file.
There are two main reasons to use aliases: One is to save typing for frequently - used combinations of actions, the other one is a gain in flexibility: If you - decide once how you want to handle shops by defining an alias called - "shop", you can later change your policy on shops in - one place, and your changes will take effect everywhere - in the actions file where the "shop" alias is used. Calling aliases - by their purpose also makes your actions files more readable.
Currently, there is one big drawback to using aliases, though: - Privoxy's built-in web-based action file - editor honors aliases when reading the actions files, but it expands - them before writing. So the effects of your aliases are of course preserved, - but the aliases themselves are lost when you edit sections that use aliases - with it.
Now let's define some aliases...
+ +
# Useful custom aliases we can use later. + +# If the response has a tag starting with 'image/' enable an external +# filter that only applies to images. +# +# Note that the filter is not available by default, it's just a +# silly example. +{+external-filter{rotate-image} +force-text-mode} +TAG:^image/ + +
+
+ + +
+
+
+
+ 8.5.34. session-cookies-only +
+
+
+
+ Typical use: +
+
+
+ Allow only temporary "session" + cookies (for the current browser session only). +
+
+
+ Effect: +
+
+
+ Deletes the "expires" field from + "Set-Cookie:" server headers. + Most browsers will not store such cookies permanently and + forget them in between sessions. +
+
+
+ Type: +
+
+
+ Boolean. +
+
+
+ Parameter: +
+
+
+ N/A +
+
+
+ Notes: +
+
+
+ This is less strict than crunch-incoming-cookies + / crunch-outgoing-cookies + and allows you to browse websites that insist or rely on + setting cookies, without compromising your privacy too + badly. +
+
+ Most browsers will not permanently store cookies that have + been processed by session-cookies-only and will forget about + them between sessions. This makes profiling cookies + useless, but won't break sites which require cookies so + that you can log in for transactions. This is generally + turned on for all sites, and is the recommended setting. +
+
+ It makes no + sense at all to use session-cookies-only together with crunch-incoming-cookies + or crunch-outgoing-cookies. + If you do, cookies will be plainly killed. +
+
+ Note that it is up to the browser how it handles such + cookies without an "expires" + field. If you use an exotic browser, you might want to try + it out to be sure. +
+
+ This setting also has no effect on cookies that may have + been stored previously by the browser before starting Privoxy. These would have to be + removed manually. +
+
+ Privoxy also uses the content-cookies + filter to block some types of cookies. Content cookies + are not effected by session-cookies-only. +
+
+
+ Example usage: +
+
+
+
+ + + + +
+
++session-cookies-only +
+
+
+
+
+
+
+
+ 8.5.35. set-image-blocker +
+
+
+
+ Typical use: +
+
+
+ Choose the replacement for blocked images +
+
+
+ Effect: +
+
+
+ This action alone doesn't do anything noticeable. If both block and handle-as-image + also + apply, i.e. if the request is to be blocked as an image, + then + the parameter of this action decides what will be sent as a + replacement. +
+
+
+ Type: +
+
+
+ Parameterized. +
+
+
+ Parameter: +
+
+
+
+
+ "pattern" to send a built-in + checkerboard pattern image. The image is visually + decent, scales very well, and makes it obvious where + banners were busted. +
+
+
+
+ "blank" to send a built-in + transparent image. This makes banners disappear + completely, but makes it hard to detect where Privoxy has blocked images + on a given page and complicates troubleshooting if + Privoxy has blocked + innocent images, like navigation icons. +
+
+
+
+ "target-url" to send a + redirect to target-url. You can redirect + to any image anywhere, even in your local filesystem + via "file:///" URL. (But + note that not all browsers support redirecting to a + local file system). +
+
+ A good application of redirects is to use special Privoxy-built-in URLs, which + send the built-in images, as target-url. This has the same + visual effect as specifying "blank" or "pattern" in the first place, but + enables your browser to cache the replacement image, + instead of requesting it over and over again. +
+
+
+
+
+ Notes: +
+
+
+ The URLs for the built-in images are "http://config.privoxy.org/send-banner?type=type", where type is either "blank" or "pattern". +
+
+ There is a third (advanced) type, called "auto". It is NOT to be used in set-image-blocker, but meant for use from filters. Auto will select the + type of image that would have applied to the referring + page, had it been an image. +
+
+
+ Example usage: +
+
+
+ Built-in pattern: +
+
+
+ + + + +
+
++set-image-blocker{pattern} +
+
+ +
+ Redirect to the BSD daemon: +
+
+
+ + + + +
+
++set-image-blocker{http://www.freebsd.org/gifs/dae_up3.gif} +
+
+ +
+ Redirect to the built-in pattern for better caching: +
+
+
+ + + + +
+
++set-image-blocker{http://config.privoxy.org/send-banner?type=pattern} +
+
+
+
+
+
+
+
+ 8.5.36. Summary +
+
+ Note that many of these actions have the potential to cause a + page to misbehave, possibly even not to display at all. There are + many ways a site designer may choose to design his site, and what + HTTP header content, and other criteria, he may depend on. There + is no way to have hard and fast rules for all sites. See the Appendix for a brief example + on troubleshooting actions. +
+
+
+
+
+ 8.6. Aliases +
+
+ Custom "actions", known to Privoxy as "aliases", can be defined by combining other + actions. These can in turn be invoked just like the built-in + actions. Currently, an alias name can contain any character except + space, tab, "=", "{" and "}", but we strongly recommend + that you only use "a" to "z", "0" to "9", "+", and "-". Alias names are not case sensitive, and + are not required to start with a "+" or + "-" sign, since they are merely + textually expanded. +
+
+ Aliases can be used throughout the actions file, but they must be defined in a special + section at the top of the file! And there can only be + one such section per actions file. Each actions file may have its + own alias section, and the aliases defined in it are only visible + within that file. +
+
+ There are two main reasons to use aliases: One is to save typing + for frequently used combinations of actions, the other one is a + gain in flexibility: If you decide once how you want to handle + shops by defining an alias called "shop", you can later change your policy on shops in + one place, + and your changes will take effect everywhere in the actions file + where the "shop" alias is used. Calling + aliases by their purpose also makes your actions files more + readable. +
+
+ Currently, there is one big drawback to using aliases, though: + Privoxy's built-in web-based + action file editor honors aliases when reading the actions files, + but it expands them before writing. So the effects of your aliases + are of course preserved, but the aliases themselves are lost when + you edit sections that use aliases with it. +
+
+ Now let's define some aliases... +
+
+
+ + +
+
+ # Useful custom aliases we can use later. # # Note the (required!) section header line and that this section # must be at the top of the actions file! @@ -6825,79 +5465,51 @@ CLASS="SCREEN" # These aliases just save typing later: # (Note that some already use other aliases!) # - +crunch-all-cookies = +crunch-incoming-cookies +crunch-outgoing-cookies - -crunch-all-cookies = -crunch-incoming-cookies -crunch-outgoing-cookies + +crunch-all-cookies = +crunch-incoming-cookies +crunch-outgoing-cookies + -crunch-all-cookies = -crunch-incoming-cookies -crunch-outgoing-cookies +block-as-image = +block{Blocked image.} +handle-as-image - allow-all-cookies = -crunch-all-cookies -session-cookies-only -filter{content-cookies} + allow-all-cookies = -crunch-all-cookies -session-cookies-only -filter{content-cookies} # These aliases define combinations of actions # that are useful for certain types of sites: # - fragile = -block -filter -crunch-all-cookies -fast-redirects -hide-referrer -prevent-compression + fragile = -block -filter -crunch-all-cookies -fast-redirects -hide-referrer -prevent-compression - shop = -crunch-all-cookies -filter{all-popups} + shop = -crunch-all-cookies -filter{all-popups} # Short names for other aliases, for really lazy people ;-) # c0 = +crunch-all-cookies - c1 = -crunch-all-cookies
...and put them to use. These sections would appear in the lower part of an - actions file and define exceptions to the default actions (as specified further - up for the "/" pattern):
+ +
# These sites are either very complex or very keen on + c1 = -crunch-all-cookies +
+
+ +
+ ...and put them to use. These sections would appear in the lower + part of an actions file and define exceptions to the default + actions (as specified further up for the "/" pattern): +
+
+
+ + +
+
+ # These sites are either very complex or very keen on # user data and require minimal interference to work: # {fragile} @@ -6908,7 +5520,7 @@ CLASS="SCREEN" # Shopping sites: # Allow cookies (for setting and retrieving your customer data) - # + # {shop} .quietpc.com .worldpay.com # for quietpc.com @@ -6918,128 +5530,140 @@ CLASS="SCREEN" # {-filter{all-popups} -filter{unsolicited-popups}} .dabs.com - .overclockers.co.uk
Aliases like "shop" and "fragile" are typically used for - "problem" sites that require more than one action to be disabled - in order to function properly.
8.7. Actions Files Tutorial
The above chapters have shown which actions files - there are and how they are organized, how actions are specified and applied - to URLs, how patterns work, and how to - define and use aliases. Now, let's look at an - example default.action and user.action - file and see how all these pieces come together:
8.7.1. default.action
Every config file should start with a short comment stating its purpose:

# Sample default.action file <ijbswa-developers@lists.sourceforge.net>
Then, since this is the default.action file, the -first section is a special section for internal use that you needn't -change or worry about:
+ +
########################################################################## + .overclockers.co.uk +
+
+ +
+ Aliases like "shop" and "fragile" are typically used for "problem" sites that require more than one action to + be disabled in order to function properly. +
+
+
+
+ 8.7. Actions Files Tutorial +
+
+ The above chapters have shown which + actions files there are and how they are organized, how actions + are specified and applied to URLs, how patterns work, and how to + define and use aliases. + Now, let's look at an example match-all.action, default.action and user.action file and see how all these pieces come + together: +
+
+
+ 8.7.1. match-all.action +
+
+ Remember all actions + are disabled when matching starts, so we have to + explicitly enable the ones we want. +
+
+ While the match-all.action file only + contains a single section, it is probably the most important one. + It has only one pattern, "/", but this pattern matches all URLs. Therefore, + the set of actions used in this "default" section will be applied to all requests as a start. + It can be partly or wholly overridden by other actions files like + default.action and user.action, but it will still be largely + responsible for your overall browsing experience. +
+
+ Again, at the start of matching, all actions are disabled, so + there is no need to disable any actions here. (Remember: a "+" preceding the action name enables the + action, a "-" disables!). Also note + how this long line has been made more readable by splitting it + into multiple lines with line continuation. +
+
+
+ + + + +
+
+{ \ + +change-x-forwarded-for{block} \ + +hide-from-header{block} \ + +set-image-blocker{pattern} \ +} +/ # Match all URLs +
+
+ +
+ The default behavior is now set. +
+
+
+
+ 8.7.2. default.action +
+
+ If you aren't a developer, there's no need for you to edit the + default.action file. It is maintained + by the Privoxy developers and if + you disagree with some of the sections, you should overrule them + in your user.action. +
+
+ Understanding the default.action file + can help you with your user.action, + though. +
+
+ The first section in this file is a special section for internal + use that prevents older Privoxy + versions from reading the file: +
+
+
+ + +
+
+########################################################################## # Settings -- Don't change! For internal Privoxy use ONLY. ########################################################################## - {{settings}} -for-privoxy-version=3.0
After that comes the (optional) alias section. We'll use the example -section from the above chapter on aliases, -that also explains why and how aliases are used:
+ +
########################################################################## +for-privoxy-version=3.0.11 +
+
+ +
+ After that comes the (optional) alias section. We'll use the + example section from the above chapter on aliases, that also + explains why and how aliases are used: +
+
+
+ + +
+
+########################################################################## # Aliases ########################################################################## {{alias}} @@ -7047,192 +5671,47 @@ CLASS="SCREEN" # These aliases just save typing later: # (Note that some already use other aliases!) # - +crunch-all-cookies = +crunch-incoming-cookies +crunch-outgoing-cookies - -crunch-all-cookies = -crunch-incoming-cookies -crunch-outgoing-cookies + +crunch-all-cookies = +crunch-incoming-cookies +crunch-outgoing-cookies + -crunch-all-cookies = -crunch-incoming-cookies -crunch-outgoing-cookies +block-as-image = +block{Blocked image.} +handle-as-image - mercy-for-cookies = -crunch-all-cookies -session-cookies-only -filter{content-cookies} + mercy-for-cookies = -crunch-all-cookies -session-cookies-only -filter{content-cookies} # These aliases define combinations of actions # that are useful for certain types of sites: # - fragile = -block -filter -crunch-all-cookies -fast-redirects -hide-referrer - shop = -crunch-all-cookies -filter{all-popups}
Now come the regular sections, i.e. sets of actions, accompanied - by URL patterns to which they apply. Remember all actions - are disabled when matching starts, so we have to explicitly - enable the ones we want.
The first regular section is probably the most important. It has only - one pattern, "/", but this pattern - matches all URLs. Therefore, the - set of actions used in this "default" section will - be applied to all requests as a start. It can be partly or - wholly overridden by later matches further down this file, or in user.action, - but it will still be largely responsible for your overall browsing - experience.
Again, at the start of matching, all actions are disabled, so there is - no need to disable any actions here. (Remember: a "+" - preceding the action name enables the action, a "-" disables!). - Also note how this long line has been made more readable by splitting it into - multiple lines with line continuation.
+ +
########################################################################## -# "Defaults" section: + fragile = -block -filter -crunch-all-cookies -fast-redirects -hide-referrer + shop = -crunch-all-cookies -filter{all-popups} +
+
+ +
+ The first of our specialized sections is concerned with "fragile" sites, i.e. sites that require + minimum interference, because they are either very complex or + very keen on tracking you (and have mechanisms in place that make + them unusable for people who avoid being tracked). We will simply + use our pre-defined fragile alias + instead of stating the list of actions explicitly: +
+
+
+ + +
+
########################################################################## - { \ - +deanimate-gifs \ - +filter{html-annoyances} \ - +filter{refresh-tags} \ - +filter{webbugs} \ - +filter{ie-exploits} \ - +hide-forwarded-for-headers \ - +hide-from-header{block} \ - +hide-referrer{forge} \ - +prevent-compression \ - +session-cookies-only \ - +set-image-blocker{pattern} \ - } - / # forward slash will match *all* potential URL patterns.
The default behavior is now set. -
The first of our specialized sections is concerned with "fragile" - sites, i.e. sites that require minimum interference, because they are either - very complex or very keen on tracking you (and have mechanisms in place that - make them unusable for people who avoid being tracked). We will simply use - our pre-defined fragile alias instead of stating the list - of actions explicitly:

########################################################################## # Exceptions for sites that'll break under the default action set: ########################################################################## @@ -7241,242 +5720,167 @@ CLASS="SCREEN" { fragile } .office.microsoft.com # surprise, surprise! .windowsupdate.microsoft.com -mail.google.com
Shopping sites are not as fragile, but they typically - require cookies to log in, and pop-up windows for shopping - carts or item details. Again, we'll use a pre-defined alias:
+ +
# Shopping sites: +mail.google.com +
+
+ +
+ Shopping sites are not as fragile, but they typically require + cookies to log in, and pop-up windows for shopping carts or item + details. Again, we'll use a pre-defined alias: +
+
+
+ + +
+
+# Shopping sites: # { shop } -.quietpc.com +.quietpc.com .worldpay.com # for quietpc.com .jungle.com -.scan.co.uk
The fast-redirects - action, which we enabled per default above, breaks some sites. So disable - it for popular sites where we know it misbehaves:
+ +
{ -fast-redirects } +.scan.co.uk +
+
+ +
+ The fast-redirects + action, which may have been enabled in match-all.action, breaks some sites. So disable + it for popular sites where we know it misbehaves: +
+
+
+ + +
+
+{ -fast-redirects } login.yahoo.com edit.*.yahoo.com .google.com .altavista.com/.*(like|url|link):http .altavista.com/trans.*urltext=http -.nytimes.com
It is important that Privoxy knows which - URLs belong to images, so that if they are to - be blocked, a substitute image can be sent, rather than an HTML page. - Contacting the remote site to find out is not an option, since it - would destroy the loading time advantage of banner blocking, and it - would feed the advertisers (in terms of money and - information). We can mark any URL as an image with the handle-as-image action, - and marking all URLs that end in a known image file extension is a - good start:
+ +
########################################################################## +.nytimes.com +
+
+ +
+ It is important that Privoxy + knows which URLs belong to images, so that if they are to be + blocked, a substitute image can be sent, rather than an HTML + page. Contacting the remote site to find out is not an option, + since it would destroy the loading time advantage of banner + blocking, and it would feed the advertisers information about + you. We can mark any URL as an image with the handle-as-image + action, and marking all URLs that end in a known image file + extension is a good start: +
+
+
+ + +
+
+########################################################################## # Images: ########################################################################## # Define which file types will be treated as images, in case they get # blocked further down this file: # -{ +handle-as-image } -/.*\.(gif|jpe?g|png|bmp|ico)$
And then there are known banner sources. They often use scripts to - generate the banners, so it won't be visible from the URL that the - request is for an image. Hence we block them and - mark them as images in one go, with the help of our - +block-as-image alias defined above. (We could of - course just as well use +block - +handle-as-image here.) - Remember that the type of the replacement image is chosen by the - set-image-blocker - action. Since all URLs have matched the default section with its - +set-image-blocker{pattern} - action before, it still applies and needn't be repeated:
+ +
# Known ad generators: +{ +handle-as-image } +/.*\.(gif|jpe?g|png|bmp|ico)$ +
+
+ +
+ And then there are known banner sources. They often use scripts + to generate the banners, so it won't be visible from the URL that + the request is for an image. Hence we block them and mark them as images + in one go, with the help of our +block-as-image alias defined above. (We could of + course just as well use +block +handle-as-image + here.) Remember that the type of the replacement image is chosen + by the set-image-blocker + action. Since all URLs have matched the default section with its + +set-image-blocker{pattern} + action before, it still applies and needn't be repeated: +
+
+
+ + +
+
+# Known ad generators: # { +block-as-image } -ar.atwola.com +ar.atwola.com .ad.doubleclick.net .ad.*.doubleclick.net .a.yimg.com/(?:(?!/i/).)*$ .a[0-9].yimg.com/(?:(?!/i/).)*$ bs*.gsanet.com -.qkimg.net
One of the most important jobs of Privoxy - is to block banners. Many of these can be "blocked" - by the filter{banners-by-size} - action, which we enabled above, and which deletes the references to banner - images from the pages while they are loaded, so the browser doesn't request - them anymore, and hence they don't need to be blocked here. But this naturally - doesn't catch all banners, and some people choose not to use filters, so we - need a comprehensive list of patterns for banner URLs here, and apply the - block action to them.
First comes many generic patterns, which do most of the work, by - matching typical domain and path name components of banners. Then comes - a list of individual patterns for specific sites, which is omitted here - to keep the example short:
+ +
########################################################################## +.qkimg.net +
+
+ +
+ One of the most important jobs of Privoxy is to block banners. Many of these + can be "blocked" by the filter{banners-by-size} + action, which we enabled above, and which deletes the references + to banner images from the pages while they are loaded, so the + browser doesn't request them anymore, and hence they don't need + to be blocked here. But this naturally doesn't catch all banners, + and some people choose not to use filters, so we need a + comprehensive list of patterns for banner URLs here, and apply + the block action to them. +
+
+ First comes many generic patterns, which do most of the work, by + matching typical domain and path name components of banners. Then + comes a list of individual patterns for specific sites, which is + omitted here to keep the example short: +
+
+
+ + +
+
+########################################################################## # Block these fine banners: ########################################################################## -{ +block{Banner ads.} } +{ +block{Banner ads.} } # Generic patterns: -# +# ad*. .*ads. banner?. @@ -7486,137 +5890,64 @@ count*. # Site-specific patterns (abbreviated): # -.hitbox.com
It's quite remarkable how many advertisers actually call their banner - servers ads.company.com, or call the directory - in which the banners are stored simply "banners". So the above - generic patterns are surprisingly effective.
But being very generic, they necessarily also catch URLs that we don't want - to block. The pattern .*ads. e.g. catches - "nasty-ads.nasty-corp.com" as intended, - but also "downloads.sourcefroge.net" or - "adsl.some-provider.net." So here come some - well-known exceptions to the +block - section above.
Note that these are exceptions to exceptions from the default! Consider the URL - "downloads.sourcefroge.net": Initially, all actions are deactivated, - so it wouldn't get blocked. Then comes the defaults section, which matches the - URL, but just deactivates the block - action once again. Then it matches .*ads., an exception to the - general non-blocking policy, and suddenly - +block applies. And now, it'll match - .*loads., where -block - applies, so (unless it matches again further down) it ends up - with no block action applying.
+ +
########################################################################## +.hitbox.com +
+
+ +
+ It's quite remarkable how many advertisers actually call their + banner servers ads.company.com, or call the directory in + which the banners are stored simply "banners". So the above generic patterns are + surprisingly effective. +
+
+ But being very generic, they necessarily also catch URLs that we + don't want to block. The pattern .*ads. + e.g. catches "nasty-ads.nasty-corp.com" as + intended, but also "downloads.sourcefroge.net" or "adsl.some-provider.net." So here + come some well-known exceptions to the +block section above. +
+
+ Note that these are exceptions to exceptions from the default! + Consider the URL "downloads.sourcefroge.net": Initially, all + actions are deactivated, so it wouldn't get blocked. Then comes + the defaults section, which matches the URL, but just deactivates + the block action once again. Then + it matches .*ads., an exception to the + general non-blocking policy, and suddenly +block applies. And now, + it'll match .*loads., where -block + applies, so (unless it matches again further down) it ends up with no block + action applying. +
+
+
+ + +
+
+########################################################################## # Save some innocent victims of the above generic block patterns: ########################################################################## # By domain: -# -{ -block } +# +{ -block } adv[io]*. # (for advogato.org and advice.*) adsl. # (has nothing to do with ads) adobe. # (has nothing to do with ads either) @@ -7631,147 +5962,100 @@ ad[ud]*. # (adult.* and add.*) # Site-specific: # www.globalintersec.com/adv # (adv = advanced) -www.ugu.com/sui/ugu/adv
Filtering source code can have nasty side effects, - so make an exception for our friends at sourceforge.net, - and all paths with "cvs" in them. Note that - -filter - disables all filters in one fell swoop!
+ +
# Don't filter code! +www.ugu.com/sui/ugu/adv +
+
+ +
+ Filtering source code can have nasty side effects, so make an + exception for our friends at sourceforge.net, and all paths with + "cvs" in them. Note that -filter + disables all filters in one fell swoop! +
+
+
+ + +
+
+# Don't filter code! # -{ -filter } +{ -filter } /(.*/)?cvs bugzilla. developer. wiki. -.sourceforge.net
The actual default.action is of course much more - comprehensive, but we hope this example made clear how it works.
8.7.2. user.action
So far we are painting with a broad brush by setting general policies, - which would be a reasonable starting point for many people. Now, - you might want to be more specific and have customized rules that - are more suitable to your personal habits and preferences. These would - be for narrowly defined situations like your ISP or your bank, and should - be placed in user.action, which is parsed after all other - actions files and hence has the last word, over-riding any previously - defined actions. user.action is also a - safe place for your personal settings, since - default.action is actively maintained by the - Privoxy developers and you'll probably want - to install updated versions from time to time.
So let's look at a few examples of things that one might typically do in - user.action:

# My user.action file. <fred@example.com>
As aliases are local to the actions - file that they are defined in, you can't use the ones from - default.action, unless you repeat them here:
+ +
# Aliases are local to the file they are defined in. +.sourceforge.net +
+
+ +
+ The actual default.action is of course + much more comprehensive, but we hope this example made clear how + it works. +
+
+
+
+ 8.7.3. user.action +
+
+ So far we are painting with a broad brush by setting general + policies, which would be a reasonable starting point for many + people. Now, you might want to be more specific and have + customized rules that are more suitable to your personal habits + and preferences. These would be for narrowly defined situations + like your ISP or your bank, and should be placed in user.action, which is parsed after all other + actions files and hence has the last word, over-riding any + previously defined actions. user.action + is also a safe place for your personal settings, + since default.action is actively + maintained by the Privoxy + developers and you'll probably want to install updated versions + from time to time. +
+
+ So let's look at a few examples of things that one might + typically do in user.action: +
+
+
+ + + + +
+
+# My user.action file. <fred@example.com> +
+
+ +
+ As aliases are local to + the actions file that they are defined in, you can't use the ones + from default.action, unless you repeat + them here: +
+
+
+ + +
+
+# Aliases are local to the file they are defined in. # (Re-)define aliases for this file: # {{alias}} -# -# These aliases just save typing later, and the alias names should +# +# These aliases just save typing later, and the alias names should # be self explanatory. # +crunch-all-cookies = +crunch-incoming-cookies +crunch-outgoing-cookies @@ -7793,83 +6077,67 @@ allow-ads = -block -filter{banners-by-size} -filter{banners-by-link} # Alias for specific file types that are text, but might have conflicting # MIME types. We want the browser to force these to be text documents. -handle-as-text = -filter +-content-type-overwrite{text/plain} +-force-text-mode -hide-content-disposition

Say you have accounts on some sites that you visit regularly, and - you don't want to have to log in manually each time. So you'd like - to allow persistent cookies for these sites. The - allow-all-cookies alias defined above does exactly - that, i.e. it disables crunching of cookies in any direction, and the - processing of cookies to make them only temporary.
+ +
{ allow-all-cookies } +handle-as-text = -filter +-content-type-overwrite{text/plain} +-force-text-mode -hide-content-disposition +
+
+
+ +
+ Say you have accounts on some sites that you visit regularly, and + you don't want to have to log in manually each time. So you'd + like to allow persistent cookies for these sites. The allow-all-cookies alias defined above does exactly + that, i.e. it disables crunching of cookies in any direction, and + the processing of cookies to make them only temporary. +
+
+
+ + +
+
+{ allow-all-cookies } sourceforge.net .yahoo.com .msdn.microsoft.com - .redhat.com
Your bank is allergic to some filter, but you don't know which, so you disable them all:

{ -filter } - .your-home-banking-site.com
Some file types you may not want to filter for various reasons:
+ +
# Technical documentation is likely to contain strings that might + .redhat.com +
+
+ +
+ Your bank is allergic to some filter, but you don't know which, + so you disable them all: +
+
+
+ + + + +
+
+{ -filter } + .your-home-banking-site.com +
+
+ +
+ Some file types you may not want to filter for various reasons: +
+
+
+ + +
+
+# Technical documentation is likely to contain strings that might # erroneously get altered by the JavaScript-oriented filters: # .tldp.org @@ -7878,355 +6146,217 @@ CLASS="SCREEN" # And this stupid host sends streaming video with a wrong MIME type, # so that Privoxy thinks it is getting HTML and starts filtering: # -stupid-server.example.com/
Example of a simple block action. Say you've - seen an ad on your favourite page on example.com that you want to get rid of. - You have right-clicked the image, selected "copy image location" - and pasted the URL below while removing the leading http://, into a - { +block{} } section. Note that { +handle-as-image - } need not be specified, since all URLs ending in - .gif will be tagged as images by the general rules as set - in default.action anyway:
+ +
{ +block{Nasty ads.} } +stupid-server.example.com/ +
+
+ +
+ Example of a simple block + action. Say you've seen an ad on your favourite page on + example.com that you want to get rid of. You have right-clicked + the image, selected "copy image + location" and pasted the URL below while removing the + leading http://, into a { +block{} } + section. Note that { +handle-as-image } + need not be specified, since all URLs ending in .gif will be tagged as images by the general rules + as set in default.action anyway: +
+
+
+ + +
+
+{ +block{Nasty ads.} } www.example.com/nasty-ads/sponsor\.gif - another.example.net/more/junk/here/
The URLs of dynamically generated banners, especially from large banner - farms, often don't use the well-known image file name extensions, which - makes it impossible for Privoxy to guess - the file type just by looking at the URL. - You can use the +block-as-image alias defined above for - these cases. - Note that objects which match this rule but then turn out NOT to be an - image are typically rendered as a "broken image" icon by the - browser. Use cautiously.
+ +
{ +block-as-image } + another.example.net/more/junk/here/ +
+
+ +
+ The URLs of dynamically generated banners, especially from large + banner farms, often don't use the well-known image file name + extensions, which makes it impossible for Privoxy to guess the file type just by + looking at the URL. You can use the +block-as-image alias defined above for these + cases. Note that objects which match this rule but then turn out + NOT to be an image are typically rendered as a "broken image" icon by the browser. Use + cautiously. +
+
+
+ + +
+
+{ +block-as-image } .doubleclick.net .fastclick.net /Realmedia/ads/ - ar.atwola.com/
Now you noticed that the default configuration breaks Forbes Magazine, - but you were too lazy to find out which action is the culprit, and you - were again too lazy to give feedback, so - you just used the fragile alias on the site, and - -- whoa! -- it worked. The fragile - aliases disables those actions that are most likely to break a site. Also, - good for testing purposes to see if it is Privoxy - that is causing the problem or not. We later find other regular sites - that misbehave, and add those to our personalized list of troublemakers:
+ +
{ fragile } + ar.atwola.com/ +
+
+ +
+ Now you noticed that the default configuration breaks Forbes + Magazine, but you were too lazy to find out which action is the + culprit, and you were again too lazy to give feedback, so you just used the fragile alias on the site, and -- whoa! -- it worked. The + fragile aliases disables those actions + that are most likely to break a site. Also, good for testing + purposes to see if it is Privoxy + that is causing the problem or not. We later find other regular + sites that misbehave, and add those to our personalized list of + troublemakers: +
+ + +
+
+{ fragile } .forbes.com webmail.example.com - .mybank.com
You like the "fun" text replacements in default.filter, - but it is disabled in the distributed actions file. - So you'd like to turn it on in your private, - update-safe config, once and for all:
{ +filter{fun} } - / # For ALL sites!
Note that the above is not really a good idea: There are exceptions - to the filters in default.action for things that - really shouldn't be filtered, like code on CVS->Web interfaces. Since - user.action has the last word, these exceptions - won't be valid for the "fun" filtering specified here.
You might also worry about how your favourite free websites are - funded, and find that they rely on displaying banner advertisements - to survive. So you might want to specifically allow banners for those - sites that you feel provide value to you:
+ +
{ allow-ads } + .mybank.com +
+
+ +
+ You like the "fun" text replacements + in default.filter, but it is disabled + in the distributed actions file. So you'd like to turn it on in + your private, update-safe config, once and for all: +
+ + + + +
+
+{ +filter{fun} } + / # For ALL sites! +
+
+ +
+ Note that the above is not really a good idea: There are + exceptions to the filters in default.action for things that really shouldn't + be filtered, like code on CVS->Web interfaces. Since user.action has the last word, these + exceptions won't be valid for the "fun" filtering specified here. +
+
+ You might also worry about how your favourite free websites are + funded, and find that they rely on displaying banner + advertisements to survive. So you might want to specifically + allow banners for those sites that you feel provide value to you: +
+ + +
+
+{ allow-ads } .sourceforge.net .slashdot.org - .osdn.net

Note that allow-ads has been aliased to - -block, - -filter{banners-by-size}, and - -filter{banners-by-link} above.
Invoke another alias here to force an over-ride of the MIME type application/x-sh which typically would open a download type - dialog. In my case, I want to look at the shell script, and then I can save - it should I choose to.
{ handle-as-text } - /.*\.sh$

user.action is generally the best place to define - exceptions and additions to the default policies of - default.action. Some actions are safe to have their - default policies set here though. So let's set a default policy to have a - "blank" image as opposed to the checkerboard pattern for - ALL sites. "/" of course matches all URL - paths and patterns:
{ +set-image-blocker{blank} } -/ # ALL sites
Prev Home Next
The Main Configuration File Filter Files
\ No newline at end of file + .osdn.net +
+
+ +

+ Note that allow-ads has been aliased to + -block, -filter{banners-by-size}, + and -filter{banners-by-link} + above. +

+ Invoke another alias here to force an over-ride of the MIME type + application/x-sh which typically would + open a download type dialog. In my case, I want to look at the + shell script, and then I can save it should I choose to. +

+ + + + +

+{ handle-as-text }
+ /.*\.sh$
+

+ +

+ user.action is generally the best place + to define exceptions and additions to the default policies of default.action. Some actions are safe to + have their default policies set here though. So let's set a + default policy to have a "blank" image + as opposed to the checkerboard pattern for ALL sites. "/" of course matches all URL paths and patterns: +

+ + + + +

+{ +set-image-blocker{blank} }
+/ # ALL sites
+

+ Prev +	+ Home +	+ Next +
+ The Main Configuration File +	+ +	+ Filter Files +