+ Allow access from any host on the 26-bit subnet 192.168.45.64 to anywhere,
+ with the exception that 192.168.45.73 may not access
+ www.dirty-stuff.example.com:
+
+ permit-access 192.168.45.64/26
+ deny-access 192.168.45.73 www.dirty-stuff.example.com
+
+-------------------------------------------------------------------------------
+
+7.4.7. buffer-limit
+
+Specifies:
+
+ Maximum size of the buffer for content filtering.
+
+Type of value:
+
+ Size in Kbytes
+
+Default value:
+
+ 4096
+
+Effect if unset:
+
+ Use a 4MB (4096 KB) limit.
+
+Notes:
+
+ For content filtering, i.e. the +filter and +deanimate-gif actions, it is
+ necessary that Privoxy buffers the entire document body. This can be
+ potentially dangerous, since a server could just keep sending data
+ indefinitely and wait for your RAM to exhaust -- with nasty consequences.
+ Hence this option.
+
+ When a document buffer size reaches the buffer-limit, it is flushed to the
+ client unfiltered and no further attempt to filter the rest of the document
+ is made. Remember that there may be multiple threads running, which might
+ require up to buffer-limit Kbytes each, unless you have enabled
+ "single-threaded" above.
+
+-------------------------------------------------------------------------------
+
+7.5. Forwarding
+
+This feature allows routing of HTTP requests through a chain of multiple
+proxies. It can be used to better protect privacy and confidentiality when
+accessing specific domains by routing requests to those domains through an
+anonymous public proxy. Or to use a caching proxy to speed up browsing. Or
+chaining to a parent proxy may be necessary because the machine that Privoxy
+runs on has no direct Internet access.
+
+Also specified here are SOCKS proxies. Privoxy supports the SOCKS 4 and SOCKS
+4A protocols.
+
+-------------------------------------------------------------------------------
+
+7.5.1. forward
+
+Specifies:
+
+ To which parent HTTP proxy specific requests should be routed.
+
+Type of value:
+
+ target_pattern http_parent[:port]
+
+ where target_pattern is a URL pattern that specifies to which requests
+ (i.e. URLs) this forward rule shall apply. Use / to denote "all URLs".
+ http_parent[:port] is the DNS name or IP address of the parent HTTP proxy
+ through which the requests should be forwarded, optionally followed by its
+ listening port (default: 8080). Use a single dot (.) to denote "no
+ forwarding".
+
+Default value:
+
+ Unset
+
+Effect if unset:
+
+ Don't use parent HTTP proxies.
+
+Notes:
+
+ If http_parent is ".", then requests are not forwarded to another HTTP
+ proxy but are made directly to the web servers.
+
+ Multiple lines are OK, they are checked in sequence, and the last match
+ wins.
+
+Examples:
+
+ Everything goes to an example anonymizing proxy, except SSL on port 443
+ (which it doesn't handle):
+
+ forward / anon-proxy.example.org:8080
+ forward :443 .
+
+ Everything goes to our example ISP's caching proxy, except for requests to
+ that ISP's sites:
+
+ forward / caching-proxy.example-isp.net:8000
+ forward .example-isp.net .
+
+-------------------------------------------------------------------------------
+
+7.5.2. forward-socks4 and forward-socks4a
+
+Specifies:
+
+ Through which SOCKS proxy (and to which parent HTTP proxy) specific
+ requests should be routed.
+
+Type of value:
+
+ target_pattern socks_proxy[:port] http_parent[:port]
+
+ where target_pattern is a URL pattern that specifies to which requests
+ (i.e. URLs) this forward rule shall apply. Use / to denote "all URLs".
+ http_parent and socks_proxy are IP addresses in dotted decimal notation or
+ valid DNS names (http_parent may be "." to denote "no HTTP forwarding"),
+ and the optional port parameters are TCP ports, i.e. integer values from 1
+ to 64535
+
+Default value:
+
+ Unset
+
+Effect if unset:
+
+ Don't use SOCKS proxies.
+
+Notes:
+
+ Multiple lines are OK, they are checked in sequence, and the last match
+ wins.
+
+ The difference between forward-socks4 and forward-socks4a is that in the
+ SOCKS 4A protocol, the DNS resolution of the target hostname happens on the
+ SOCKS server, while in SOCKS 4 it happens locally.
+
+ If http_parent is ".", then requests are not forwarded to another HTTP
+ proxy but are made (HTTP-wise) directly to the web servers, albeit through
+ a SOCKS proxy.
+
+Examples:
+
+ From the company example.com, direct connections are made to all "internal"
+ domains, but everything outbound goes through their ISP's proxy by way of
+ example.com's corporate SOCKS 4A gateway to the Internet.
+
+ forward-socks4a / socks-gw.example.com:1080 www-cache.example-isp.net:8080
+ forward .example.com .
+
+ A rule that uses a SOCKS 4 gateway for all destinations but no HTTP parent
+ looks like this:
+
+ forward-socks4 / socks-gw.example.com:1080 .
+
+ To chain Privoxy and Tor, both running on the same system, you should use
+ the rule:
+
+ forward-socks4 / 127.0.0.1:9050 .
+
+ The public Tor network can't be used to reach your local network, therefore
+ it's a good idea to make some exceptions:
+
+ forward 192.168.*.*/ .
+ forward 10.*.*.*/ .
+ forward 127.*.*.*/ .
+
+ Unencrypted connections to systems in these address ranges will be as (un)
+ secure as the local network is, but the alternative is that you can't reach
+ the network at all.
+
+ If you also want to be able to reach servers in your local network by using
+ their names, you will need additional exceptions that look like this:
+
+ forward localhost/ .
+
+-------------------------------------------------------------------------------
+
+7.5.3. Advanced Forwarding Examples
+
+If you have links to multiple ISPs that provide various special content only to
+their subscribers, you can configure multiple Privoxies which have connections
+to the respective ISPs to act as forwarders to each other, so that your users
+can see the internal content of all ISPs.
+
+Assume that host-a has a PPP connection to isp-a.net. And host-b has a PPP
+connection to isp-b.net. Both run Privoxy. Their forwarding configuration can
+look like this:
+
+host-a:
+
+ forward / .
+ forward .isp-b.net host-b:8118
+
+host-b:
+
+ forward / .
+ forward .isp-a.net host-a:8118
+
+Now, your users can set their browser's proxy to use either host-a or host-b
+and be able to browse the internal content of both isp-a and isp-b.
+
+If you intend to chain Privoxy and squid locally, then chain as browser ->
+squid -> privoxy is the recommended way.
+
+Assuming that Privoxy and squid run on the same box, your squid configuration
+could then look like this:
+
+ # Define Privoxy as parent proxy (without ICP)
+ cache_peer 127.0.0.1 parent 8118 7 no-query
+
+ # Define ACL for protocol FTP
+ acl ftp proto FTP
+
+ # Do not forward FTP requests to Privoxy
+ always_direct allow ftp
+
+ # Forward all the rest to Privoxy
+ never_direct allow all
+
+You would then need to change your browser's proxy settings to squid's address
+and port. Squid normally uses port 3128. If unsure consult http_port in
+squid.conf.
+
+You could just as well decide to only forward requests for Windows executables
+through a virus-scanning parent proxy, say, on antivir.example.com, port 8010:
+
+ forward / .
+ forward /.*\.(exe|com|dll|zip)$ antivir.example.com:8010
+
+-------------------------------------------------------------------------------
+
+7.5.4. forwarded-connect-retries
+
+Specifies:
+
+ How often Privoxy retries if a forwarded connection request fails.
+
+Type of value:
+
+ Number of retries.
+
+Default value:
+
+ 0
+
+Effect if unset:
+
+ Forwarded connections are treated like direct connections and no retry
+ attempts are made.
+
+Notes:
+
+ forwarded-connect-retries is mainly interesting for socks4a connections,
+ where Privoxy can't detect why the connections failed. The connection might
+ have failed because of a DNS timeout in which case a retry makes sense, but
+ it might also have failed because the server doesn't exist or isn't
+ reachable. In this case the retry will just delay the appearance of
+ Privoxy's error message.
+
+ Only use this option, if you are getting many forwarding related error
+ messages, that go away when you try again manually. Start with a small
+ value and check Privoxy's logfile from time to time, to see how many
+ retries are usually needed.
+
+Examples:
+
+ forwarded-connect-retries 1
+
+-------------------------------------------------------------------------------
+
+7.6. Windows GUI Options
+
+Privoxy has a number of options specific to the Windows GUI interface:
+
+If "activity-animation" is set to 1, the Privoxy icon will animate when
+"Privoxy" is active. To turn off, set to 0.
+
+ activity-animation 1
+
+
+If "log-messages" is set to 1, Privoxy will log messages to the console window:
+
+ log-messages 1
+
+
+If "log-buffer-size" is set to 1, the size of the log buffer, i.e. the amount
+of memory used for the log messages displayed in the console window, will be
+limited to "log-max-lines" (see below).
+
+Warning: Setting this to 0 will result in the buffer to grow infinitely and eat
+up all your memory!
+
+ log-buffer-size 1
+
+
+log-max-lines is the maximum number of lines held in the log buffer. See above.
+
+ log-max-lines 200
+
+
+If "log-highlight-messages" is set to 1, Privoxy will highlight portions of the
+log messages with a bold-faced font:
+
+ log-highlight-messages 1
+
+
+The font used in the console window:
+
+ log-font-name Comic Sans MS
+
+
+Font size used in the console window:
+
+ log-font-size 8
+
+
+"show-on-task-bar" controls whether or not Privoxy will appear as a button on
+the Task bar when minimized:
+
+ show-on-task-bar 0
+
+
+If "close-button-minimizes" is set to 1, the Windows close button will minimize
+Privoxy instead of closing the program (close with the exit option on the File
+menu).
+
+ close-button-minimizes 1
+
+
+The "hide-console" option is specific to the MS-Win console version of Privoxy.
+If this option is used, Privoxy will disconnect from and hide the command
+console.
+
+ #hide-console
+
+
+-------------------------------------------------------------------------------
+
+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 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 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 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 ad blocking 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 |medium |high |high |
+ |Aggressiveness | | | |
+ |------------------+-----------------+------------------+-----------------|
+ |Ad-filtering by |no |yes |yes |
+ |size | | | |
+ |------------------+-----------------+------------------+-----------------|
+ |Ad-filtering by |no |no |yes |
+ |link | | | |
+ |------------------+-----------------+------------------+-----------------|
+ |Pop-up killing |blocks only |blocks only |all |
+ |------------------+-----------------+------------------+-----------------|
+ |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 |yes |yes |
+ |------------------+-----------------+------------------+-----------------|
+ |JavaScript taming |no |yes |yes |
+ |------------------+-----------------+------------------+-----------------|
+ |Web-bug killing |no |yes |yes |
+ |------------------+-----------------+------------------+-----------------|
+ |Image tag |no |no |yes |
+ |reordering | | | |
+ +-------------------------------------------------------------------------+
+
+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 process 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 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 that 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, 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. 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 URLs
+
+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 patterns, each
+on a separate line.
+
+To determine which actions apply to a request, the URL of the request is
+compared to all patterns in each "action file" file. Every time it matches, the
+list of applicable actions for the URL is incrementally updated, using the
+heading of the section in which the pattern is located. If multiple matches for
+the same URL 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 }
+ # 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 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, a Privoxy 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 a more flexible "Regular Expressions (PCRE)" based syntax.
+
+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 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 that ENDS in .example.com
+
+www.
+
+ matches any domain that STARTS with www.
+
+.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 flexibile, this is not the sophistication of full regular expression
+based syntax.
+
+-------------------------------------------------------------------------------
+
+8.4.2. The Path Pattern
+
+Privoxy uses Perl compatible (PCRE) "Regular Expression" based syntax (through
+the PCRE library) 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, and
+full (very technical) documentation on PCRE regex syntax is available on-line
+at http://www.pcre.org/man.txt. You might also find the Perl man page on
+regular expressions (man perlre) useful, which is available on-line at http://
+perldoc.perl.org/perlre.html.
+
+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.
+
+-------------------------------------------------------------------------------
+
+8.5. 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: +block
+
+ * 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 1.0 }
+
+ * 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-anonymizing 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 actions always over-ride earlier ones. 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 pattern to match more than one pattern and thus 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:
+
+ Boolean.
+
+Parameter:
+
+ N/A
+
+Notes:
+
+ Privoxy sends a special "BLOCKED" page for requests to blocked pages. This
+ page contains links to find out why the request was blocked, and a
+ click-through to the blocked content (the latter only if compiled with the
+ force feature enabled). The "BLOCKED" page adapts to the available screen
+ space -- it displays full-blown if space allows, or miniaturized and
+ text-only if loaded into a small frame or window. If you are using Privoxy
+ right now, you can take a look at the "BLOCKED" page.
+
+ 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}
+ # Block and replace with "blocked" page
+ .nasty-stuff.example.com
+
+ {+block +handle-as-image}
+ # Block and replace with image
+ .ad.doubleclick.net
+ .ads.r.us/banners/
+
+ {+block +handle-as-empty-document}
+ # Block and then ignore
+ adserver.exampleclick.net/.*\.js$
+
+-------------------------------------------------------------------------------
+
+8.5.3. 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 enable filter-server-headers and replace
+ this action with a custom regular expression. 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
+
+-------------------------------------------------------------------------------
+
+8.5.4. 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
+ enable filter-client-headers and create your own 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:}}
+ /
+
+
+-------------------------------------------------------------------------------
+
+8.5.5. 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.
+
+ Blocking the "If-None-Match:" header shouldn't cause any caching problems,
+ as long as the "If-Modified-Since:" header isn't blocked 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 without being tracked across sessions
+ {+hide-if-modified-since {-60} \
+ +overwrite-last-modified {randomize} \
+ +crunch-if-none-match}
+ /
+
+-------------------------------------------------------------------------------
+
+8.5.6. crunch-incoming-cookies
+
+Typical use:
+
+ Prevent the web server from setting any 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 cookies. For outgoing cookies,
+ use crunch-outgoing-cookies. Use both to disable 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
+
+-------------------------------------------------------------------------------
+
+8.5.7. 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
+ enable filter-server-headers and create your own 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}}
+ /
+
+-------------------------------------------------------------------------------
+
+8.5.8. crunch-outgoing-cookies
+
+Typical use:
+
+ Prevent the web server from reading any 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 cookies. For incoming cookies,
+ use crunch-incoming-cookies. Use both to disable 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
+
+-------------------------------------------------------------------------------
+
+8.5.9. 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}
+
+-------------------------------------------------------------------------------
+
+8.5.10. 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
+ (optional) HTTP/1.1 features are supported yet, so there is a chance you
+ might need this action.
+
+Example usage (section):
+
+ {+downgrade-http-version}
+ problem-host.example.com
+
+-------------------------------------------------------------------------------
+
+8.5.11. 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. It is possible to fix
+ these redirected requests with filter-client-headers 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} }
+ .example.com
+
+ { +fast-redirects{check-decoded-url} }
+ another.example.com/testing
+
+-------------------------------------------------------------------------------
+
+8.5.12. filter
+
+Typical use:
+
+ Get rid of HTML and JavaScript annoyances, banner advertisements (by size),
+ do fun text replacements, etc.
+
+Effect:
+
+ All files of text-based type, most notably HTML and JavaScript, to which
+ this action applies, are 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.) By default,
+ filtering works only on the raw document content itself (that which can be
+ seen with View Source), not the headers.
+
+Type:
+
+ Parameterized.
+
+Parameter:
+
+ The name of a 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.
+ Use with caution.
+
+ 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.
+
+ At this time, Privoxy cannot uncompress compressed documents. If you want
+ filtering to work on all documents, even those that would normally be sent
+ compressed, use the prevent-compression action in conjunction with filter.
+
+ 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 (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
+
+ +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 resizeable
+
+ +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 savable
+
+ +filter{fun} # Text replacements for subversive browsing fun!
+
+ +filter{crude-parental} # Crude parental filtering (demo only)
+
+ +filter{ie-exploits} # Disable some known Internet Explorer bug exploits
+
+-------------------------------------------------------------------------------
+
+8.5.13. filter-client-headers
+
+Typical use:
+
+ To apply filtering to the client's (browser's) headers
+
+Effect:
+
+ By default, Privoxy's filters only apply to the document content itself.
+ This will extend those filters to include the client's headers as well.
+
+Type:
+
+ Boolean.
+
+Parameter:
+
+ N/A
+
+Notes:
+
+ Regular expressions can be used to filter headers as well. Check your
+ filters closely before activating this action, as it can easily lead to
+ broken requests.
+
+ These filters are applied to each header on its own, not to them 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.
+
+ The filters are used after the other header actions have finished and can
+ use their output as input.
+
+ Whenever possible one should specify ^, $, the whole header name and the
+ colon, to make sure the filter doesn't cause havoc to other headers or the
+ page itself. For example if you want to transform Galeon User-Agents to
+ Firefox User-Agents you shouldn't use:
+
+ s@Galeon/\d\.\d\.\d @@
+
+ but:
+
+ s@^(User-Agent:.*) Galeon/\d\.\d\.\d (Firefox/\d\.\d\.\d\.\d)$@$1 $2@
+
+Example usage (section):
+
+ {+filter-client-headers +filter{test_filter}}
+ problem-host.example.com
+
+
+-------------------------------------------------------------------------------
+
+8.5.14. filter-server-headers
+
+Typical use:
+
+ To apply filtering to the server's headers
+
+Effect:
+
+ By default, Privoxy's filters only apply to the document content itself.
+ This will extend those filters to include the server's headers as well.
+
+Type:
+
+ Boolean.
+
+Parameter:
+
+ N/A
+
+Notes:
+
+ Similar to filter-client-headers, but works on the server instead. To
+ filter both server and client, use both.
+
+ As with filter-client-headers, check your filters before activating this
+ action, as it can easily lead to broken requests.
+
+ These filters are applied to each header on its own, not to them 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.
+
+ The filters are used after the other header actions have finished and can
+ use their output as input.
+
+ Remember too, whenever possible one should specify ^, $, the whole header
+ name and the colon, to make sure the filter doesn't cause havoc to other
+ headers or the page itself. See above for example.
+
+Example usage (section):
+
+ {+filter-server-headers +filter{test_filter}}
+ problem-host.example.com
+
+
+-------------------------------------------------------------------------------
+
+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. 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.
+
+ 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 +handle-as-empty-document}
+ example.org/.*\.js$
+
+
+-------------------------------------------------------------------------------
+
+8.5.17. 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)$
+
+ # These don't look like images, but they're banners and should be
+ # blocked as images:
+ #
+ {+block +handle-as-image}
+ some.nasty-banner-server.com/junk.cgi?output=trash
+
+ # Banner source! Who cares if they also have non-image content?
+ ad.doubleclick.net
+
+-------------------------------------------------------------------------------
+
+8.5.18. 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} \
+ }
+ /
+
+-------------------------------------------------------------------------------
+
+8.5.19. 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.
+
+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
+
+-------------------------------------------------------------------------------
+
+8.5.20. 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 sure it isn't used
+ 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.
+
+Example usage (section):
+
+ # Let the browser revalidate without being tracked across sessions
+ {+hide-if-modified-since {-60}\
+ +overwrite-last-modified {randomize}\
+ +crunch-if-none-match}
+ /
+
+-------------------------------------------------------------------------------
+
+8.5.21. hide-forwarded-for-headers
+
+Typical use:
+
+ Improve privacy by hiding the true source of the request
+
+Effect:
+
+ Deletes any existing "X-Forwarded-for:" HTTP header from client requests,
+ and prevents adding a new one.
+
+Type:
+
+ Boolean.
+
+Parameter:
+
+ N/A
+
+Notes:
+
+ It is fairly safe to leave this on.
+
+ This action is scheduled for improvement: It should be able to generate
+ forged "X-Forwarded-for:" headers using random IP addresses from a
+ specified network, to make successive requests from the same client look
+ like requests from a pool of different users sharing the same proxy.
+
+Example usage:
+
+ +hide-forwarded-for-headers
+
+-------------------------------------------------------------------------------
+
+8.5.22. 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}
+
+-------------------------------------------------------------------------------
+
+8.5.23. 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.
+
+ + "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 valuable 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/}
+
+-------------------------------------------------------------------------------
+
+8.5.24. hide-user-agent
+
+Typical use:
+
+ 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 :-).
+
+ This action is scheduled for improvement.
+
+Example usage:
+
+ +hide-user-agent{Netscape 6.1 (X11; I; Linux 2.4.18 i686)}
+
+-------------------------------------------------------------------------------
+
+8.5.25. inspect-jpegs
+
+Typical use:
+
+ To protect against the MS buffer over-run in JPEG processing
+
+Effect:
+
+ Protect against a known exploit
+
+Type:
+
+ Boolean.
+
+Parameter:
+
+ N/A
+
+Notes:
+
+ See Microsoft Security Bulletin MS04-028. JPEG images are one of the most
+ common image types found across the Internet. The exploit as described can
+ allow execution of code on the target system, giving an attacker access to
+ the system in question by merely planting an altered JPEG image, which
+ would have no obvious indications of what lurks inside. This action
+ prevents unwanted intrusion.
+
+Example usage:
+
+ +inspect-jpegs
+
+-------------------------------------------------------------------------------
+
+8.5.26. kill-popups
+
+Typical use:
+
+ Eliminate those annoying pop-up windows (deprecated)
+
+Effect:
+
+ While loading the document, replace JavaScript code that opens pop-up
+ windows with (syntactically neutral) dummy code on the fly.
+
+Type:
+
+ Boolean.
+
+Parameter:
+
+ N/A
+
+Notes:
+
+ This action is basically a built-in, hardwired special-purpose filter
+ action, but there are important differences: For kill-popups, the document
+ need not be buffered, so it can be incrementally rendered while
+ downloading. But kill-popups doesn't catch as many pop-ups as filter
+ {all-popups} does and is not as smart as filter{unsolicited-popups} is.
+
+ Think of it as a fast and efficient replacement for a filter that you can
+ use if you don't want any filtering at all. Note that it doesn't make sense
+ to combine it with any filter action, since as soon as one filter applies,
+ the whole document needs to be buffered anyway, which destroys the
+ advantage of the kill-popups action over its filter equivalent.
+
+ Killing all pop-ups unconditionally is problematic. Many shops and banks
+ rely on pop-ups to display forms, shopping carts etc, and the filter
+ {unsolicited-popups} does a fairly good job of catching only the unwanted
+ ones.
+
+ If the only kind of pop-ups that you want to kill are exit consoles (those
+ really nasty windows that appear when you close an other one), you might
+ want to use filter{js-annoyances} instead.
+
+Example usage:
+
+ +kill-popups
+
+-------------------------------------------------------------------------------
+
+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 only allows
+ HTTP CONNECT requests to port 443 (the standard, secure HTTPS port). Use
+ limit-connect if more 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 can be a big
+ security hole, since CONNECT-enabled proxies can be abused 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. If you plan to
+ disable SSL by default, consider enabling
+ treat-forbidden-connects-like-blocks as well, to be able to quickly create
+ exceptions.
+
+Example usages:
+
+ +limit-connect{443} # This is the default and need not be specified.
+ +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
+
+-------------------------------------------------------------------------------
+
+8.5.28. 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 for the filter,
+ deanimate-gifs and kill-popups actions to work, Privoxy needs access to the
+ uncompressed data. Unfortunately, Privoxy can't yet(!) uncompress, filter,
+ and re-compress the content on the fly. So if you want to ensure that all
+ websites, including those that normally compress, can be filtered, you need
+ to use this action.
+
+ This will slow down transfers from those websites, though. If you use any
+ of the above-mentioned actions, you will typically want to use
+ prevent-compression in conjunction with them.
+
+ Note that some (rare) ill-configured sites don't handle requests for
+ uncompressed documents correctly (they send an empty document body). If you
+ use prevent-compression per default, you'll have to add exceptions for
+ those sites. See the example for how to do that.
+
+Example usage (sections):
+
+ # Set default:
+ #
+ {+prevent-compression}
+ / # Match all sites
+
+ # Make exceptions for ill sites:
+ #
+ {-prevent-compression}
+ www.debianhelp.org
+ www.pclinuxonline.com
+
+-------------------------------------------------------------------------------
+
+8.5.29. 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
+ {+hide-if-modified-since {-60}\
+ +overwrite-last-modified {randomize}\
+ +crunch-if-none-match}
+ /
+
+-------------------------------------------------------------------------------
+
+8.5.30. 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:
+
+ Any URL.
+
+Notes:
+
+ This action is useful to replace whole documents with ones of your
+ choosing. This can be used to enforce safe surfing, or just as a simple
+ convenience.
+
+ You can do the same by combining the actions block, handle-as-image and
+ set-image-blocker{URL}. It doesn't sound right for non-image documents, and
+ that's why this action was created.
+
+ This action will be ignored if you use it together with block.
+
+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
+ { +redirect{http://www.privoxy.org/user-manual/actions-file.html} }
+ a
+
+-------------------------------------------------------------------------------
+
+8.5.31. send-vanilla-wafer
+
+Typical use:
+
+ Feed log analysis scripts with useless data.
+
+Effect:
+
+ Sends a cookie with each request stating that you do not accept any
+ copyright on cookies sent to you, and asking the site operator not to track
+ you.
+
+Type:
+
+ Boolean.
+
+Parameter:
+
+ N/A
+
+Notes:
+
+ The vanilla wafer is a (relatively) unique header and could conceivably be
+ used to track you.
+
+ This action is rarely used and not enabled in the default configuration.
+
+Example usage:
+
+ +send-vanilla-wafer
+
+-------------------------------------------------------------------------------
+
+8.5.32. send-wafer
+
+Typical use:
+
+ Send custom cookies or feed log analysis scripts with even more useless
+ data.
+
+Effect:
+
+ Sends a custom, user-defined cookie with each request.
+
+Type:
+
+ Multi-value.
+
+Parameter:
+
+ A string of the form "name=value".
+
+Notes:
+
+ Being multi-valued, multiple instances of this action can apply to the same
+ request, resulting in multiple cookies being sent.
+
+ This action is rarely used and not enabled in the default configuration.
+
+Example usage (section):
+
+ {+send-wafer{UsingPrivoxy=true}}
+ my-internal-testing-server.void
+
+-------------------------------------------------------------------------------
+
+8.5.33. 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
+
+-------------------------------------------------------------------------------
+
+8.5.34. 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 devil:
+
+ +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}
+
+-------------------------------------------------------------------------------
+
+8.5.35. treat-forbidden-connects-like-blocks
+
+Typical use:
+
+ Block forbidden connects with an easy to find error message.
+
+Effect:
+
+ If this action is enabled, Privoxy no longer makes a difference between
+ forbidden connects and ordinary blocks.
+
+Type:
+
+ Boolean
+
+Parameter:
+
+ N/A
+
+Notes:
+
+ By default Privoxy answers forbidden "Connect" requests with a short error
+ message inside the headers. If the browser doesn't display headers (most
+ don't), you just see an empty page.
+
+ With this action enabled, Privoxy displays the message that is used for
+ ordinary blocks instead. If you decide to make an exception for the page in
+ question, you can do so by following the "See why" link.
+
+ For "Connect" requests the clients tell Privoxy which host they are
+ interested in, but not which document they plan to get later. As a result,
+ the "Go there anyway" link becomes rather useless: it lets the client
+ request the home page of the forbidden host through unencrypted HTTP, still
+ using the port of the last request.
+
+ If you previously configured Privoxy to do the request through a SSL
+ tunnel, everything will work. Most likely you haven't and the server will
+ respond with an error message because it is expecting HTTPS (SSL).
+
+Example usage:
+
+ +treat-forbidden-connects-like-blocks
+
+-------------------------------------------------------------------------------
+
+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. This is likely to change in future versions of
+Privoxy.
+
+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!
+ #
+ {{alias}}
+
+ # 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
+ +block-as-image = +block +handle-as-image
+ 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 -kill-popups
+ shop = -crunch-all-cookies -filter{all-popups} -kill-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
+ # user data and require minimal interference to work:
+ #
+ {fragile}
+ .office.microsoft.com
+ .windowsupdate.microsoft.com
+ .nytimes.com
+
+ # Shopping sites:
+ # Allow cookies (for setting and retrieving your customer data)
+ #
+ {shop}
+ .quietpc.com
+ .worldpay.com # for quietpc.com
+ .scan.co.uk
+
+ # These shops require pop-ups:
+ #
+ {shop -kill-popups -filter{all-popups}}
+ .dabs.com
+ .overclockers.co.uk
+
+Aliases like "shop" and "fragile" are often used for "problem" sites that
+require some actions 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:
+
+##########################################################################
+# 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:
+
+##########################################################################
+# Aliases
+##########################################################################
+{{alias}}
+
+ # 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
+ +block-as-image = +block +handle-as-image
+ 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 -kill-popups
+ shop = -crunch-all-cookies -filter{all-popups} -kill-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 real
+need to disable any actions here, but we will do that nonetheless, to have a
+complete listing for your reference. (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:
+##########################################################################
+ { \
+ -add-header \
+ -block \
+ -content-type-overwrite \
+ -crunch-client-header \
+ -crunch-if-none-match \
+ -crunch-incoming-cookies \
+ -crunch-server-header \
+ -crunch-outgoing-cookies \
+ +deanimate-gifs \
+ -downgrade-http-version \
+ +fast-redirects{check-decoded-url} \
+ +filter{js-annoyances} \
+ -filter{js-events} \
+ +filter{html-annoyances} \
+ -filter{content-cookies} \
+ +filter{refresh-tags} \
+ +filter{unsolicited-popups} \
+ -filter{all-popups} \
+ +filter{img-reorder} \
+ +filter{banners-by-size} \
+ -filter{banners-by-link} \
+ +filter{webbugs} \
+ -filter{tiny-textforms} \
+ +filter{jumping-windows} \
+ -filter{frameset-borders} \
+ -filter{demoronizer} \
+ -filter{shockwave-flash} \
+ -filter{quicktime-kioskmode} \
+ -filter{fun} \
+ -filter{crude-parental} \
+ +filter{ie-exploits} \
+ -filter-client-headers \
+ -filter-server-headers \
+ -force-text-mode \
+ -handle-as-empty-document \
+ -handle-as-image \
+ -hide-accept-language \
+ -hide-content-disposition \
+ -hide-if-modified-since \
+ +hide-forwarded-for-headers \
+ +hide-from-header{block} \
+ +hide-referrer{forge} \
+ -hide-user-agent \
+ -inspect-jpegs \
+ -kill-popups \
+ -limit-connect \
+ +prevent-compression \
+ -overwrite-last-modified \
+ -redirect \
+ -send-vanilla-wafer \
+ -send-wafer \
+ +session-cookies-only \
+ +set-image-blocker{pattern} \
+ -treat-forbidden-connects-like-blocks \
+ }
+ / # forward slash will match *all* potential URL patterns.
+
+The default behavior is now set. Note that some actions, like not hiding the
+user agent, are part of a "general policy" that applies universally and won't
+get any exceptions defined later. Other choices, like not blocking (which is
+understandably the default!) need exceptions, i.e. we need to specify
+explicitly what we want to block in later sections.
+
+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:
+##########################################################################
+
+# "Fragile" Use a minimum set of actions for these sites (see alias above):
+#
+{ fragile }
+.office.microsoft.com # surprise, surprise!
+.windowsupdate.microsoft.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
+.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 }
+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:
+
+##########################################################################
+# 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:
+#
+{ +block-as-image }
+ar.atwola.com
+.ad.doubleclick.net
+.ad.*.doubleclick.net
+.a.yimg.com/(?:(?!/i/).)*$
+.a[0-9].yimg.com/(?:(?!/i/).)*$
+bs*.gsanet.com
+bs*.einets.com
+.qkimg.net
+
+One of the most important jobs of Privoxy is to block banners. A huge bunch of
+them 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 a bunch of 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 }
+
+# Generic patterns:
+#
+ad*.
+.*ads.
+banner?.
+count*.
+/.*count(er)?\.(pl|cgi|exe|dll|asp|php[34]?)
+/(?:.*/)?(publicite|werbung|rekla(ma|me|am)|annonse|maino(kset|nta|s)?)/
+
+# Site-specific patterns (abbreviated):
+#
+.hitbox.com
+
+You wouldn't believe 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 }
+adv[io]*. # (for advogato.org and advice.*)
+adsl. # (has nothing to do with ads)
+ad[ud]*. # (adult.* and add.*)
+.edu # (universities don't host banners (yet!))
+.*loads. # (downloads, uploads etc)
+
+# By path:
+#
+/.*loads/
+
+# 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!
+#
+{ -filter }
+/.*cvs
+.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@foobar.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
+# be self explanatory.
+#
++crunch-all-cookies = +crunch-incoming-cookies +crunch-outgoing-cookies
+-crunch-all-cookies = -crunch-incoming-cookies -crunch-outgoing-cookies
+ allow-all-cookies = -crunch-all-cookies -session-cookies-only
+ allow-popups = -filter{all-popups} -kill-popups
++block-as-image = +block +handle-as-image
+-block-as-image = -block
+
+# These aliases define combinations of actions that are useful for
+# certain types of sites:
+#
+fragile = -block -crunch-all-cookies -filter -fast-redirects -hide-referrer -kill-popups
+shop = -crunch-all-cookies allow-popups
+
+# Allow ads for selected useful free sites:
+#
+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 }
+ 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
+# erroneously get altered by the JavaScript-oriented filters:
+#
+.tldp.org
+/(.*/)?selfhtml/
+
+# 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 }
+ www.example.com/nasty-ads/sponsor.gif
+ another.popular.site.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 }
+ .forbes.com
+ mail.example.com
+ .mybank.com
+
+You like the "fun" text replacements in default.filter, but it is disabled in
+the distributed actions file. (My colleagues on the team just don't have a
+sense of humour, that's why! ;-). 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
+
+-------------------------------------------------------------------------------
+
+9. Filter Files
+
+On-the-fly text substitutions that can be invoked through the filter action
+need to be defined in a "filter file". Once defined, they can then be invoked
+as an "action". Multiple filter files can be defined through the filterfile
+config directive. The filters as supplied by the developers will be found in
+default.filter. It is recommended that any locally defined or modified filters
+go in a separately defined file such as user.filter.
+
+Typical reasons for doing these kinds of substitutions are to eliminate common
+annoyances in HTML and JavaScript, such as pop-up windows, exit consoles,
+crippled windows without navigation tools, the infamous <BLINK> tag etc, to
+suppress images with certain width and height attributes (standard banner sizes
+or web-bugs), or just to have fun. The possibilities are endless.
+
+Filtering works on any text-based document type, including HTML, JavaScript,
+CSS etc. (all text/* MIME types, except text/plain). Substitutions are made at
+the source level, so if you want to "roll your own" filters, you should first
+be familiar with HTML syntax, and, of course, regular expressions. By default,
+filters are only applied to the raw document content, but can be extended to
+the HTTP headers with the supplemental actions: filter-client-headers and
+filter-server-headers.
+
+Just like the actions files, the filter file is organized in sections, which
+are called filters here. Each filter consists of a heading line, that starts
+with the keyword FILTER:, followed by the filter's name, and a short (one line)
+description of what it does. Below that line come the jobs, i.e. lines that
+define the actual text substitutions. By convention, the name of a filter
+should describe what the filter eliminates. The comment is used in the
+web-based user interface.
+
+Once a filter called name has been defined in the filter file, it can be
+invoked by using an action of the form +filter{name} in any actions file.
+
+A filter header line for a filter called "foo" could look like this:
+
+FILTER: foo Replace all "foo" with "bar"
+
+Below that line, and up to the next header line, come the jobs that define what
+text replacements the filter executes. They are specified in a syntax that
+imitates Perl's s/// operator. If you are familiar with Perl, you will find
+this to be quite intuitive, and may want to look at the PCRS documentation for
+the subtle differences to Perl behaviour. Most notably, the non-standard option
+letter U is supported, which turns the default to ungreedy matching.
+
+If you are new to "Regular Expressions", you might want to take a look at the
+Appendix on regular expressions, and see the Perl manual for the s///
+operator's syntax and Perl-style regular expressions in general. The below
+examples might also help to get you started.
+
+-------------------------------------------------------------------------------
+
+9.1. Filter File Tutorial
+
+Now, let's complete our "foo" filter. We have already defined the heading, but
+the jobs are still missing. Since all it does is to replace "foo" with "bar",
+there is only one (trivial) job needed:
+
+s/foo/bar/
+
+But wait! Didn't the comment say that all occurrences of "foo" should be
+replaced? Our current job will only take care of the first "foo" on each page.
+For global substitution, we'll need to add the g option:
+
+s/foo/bar/g
+
+Our complete filter now looks like this:
+
+FILTER: foo Replace all "foo" with "bar"
+s/foo/bar/g
+
+Let's look at some real filters for more interesting examples. Here you see a
+filter that protects against some common annoyances that arise from JavaScript
+abuse. Let's look at its jobs one after the other:
+
+FILTER: js-annoyances Get rid of particularly annoying JavaScript abuse
+
+# Get rid of JavaScript referrer tracking. Test page: http://www.randomoddness.com/untitled.htm
+#
+s|(<script.*)document\.referrer(.*</script>)|$1"Not Your Business!"$2|Usg
+
+Following the header line and a comment, you see the job. Note that it uses |
+as the delimiter instead of /, because the pattern contains a forward slash,
+which would otherwise have to be escaped by a backslash (\).
+
+Now, let's examine the pattern: it starts with the text <script.* enclosed in
+parentheses. Since the dot matches any character, and * means: "Match an
+arbitrary number of the element left of myself", this matches "<script",
+followed by any text, i.e. it matches the whole page, from the start of the
+first <script> tag.
+
+That's more than we want, but the pattern continues: document\.referrer matches
+only the exact string "document.referrer". The dot needed to be escaped, i.e.
+preceded by a backslash, to take away its special meaning as a joker, and make
+it just a regular dot. So far, the meaning is: Match from the start of the
+first <script> tag in a the page, up to, and including, the text
+"document.referrer", if both are present in the page (and appear in that
+order).
+
+But there's still more pattern to go. The next element, again enclosed in
+parentheses, is .*</script>. You already know what .* means, so the whole
+pattern translates to: Match from the start of the first <script> tag in a page
+to the end of the last <script> tag, provided that the text "document.referrer"
+appears somewhere in between.
+
+This is still not the whole story, since we have ignored the options and the
+parentheses: The portions of the page matched by sub-patterns that are enclosed
+in parentheses, will be remembered and be available through the variables $1,
+$2, ... in the substitute. The U option switches to ungreedy matching, which
+means that the first .* in the pattern will only "eat up" all text in between "
+<script" and the first occurrence of "document.referrer", and that the second .
+* will only span the text up to the first "</script>" tag. Furthermore, the s
+option says that the match may span multiple lines in the page, and the g
+option again means that the substitution is global.
+
+So, to summarize, the pattern means: Match all scripts that contain the text
+"document.referrer". Remember the parts of the script from (and including) the
+start tag up to (and excluding) the string "document.referrer" as $1, and the
+part following that string, up to and including the closing tag, as $2.
+
+Now the pattern is deciphered, but wasn't this about substituting things? So
+lets look at the substitute: $1"Not Your Business!"$2 is easy to read: The text
+remembered as $1, followed by "Not Your Business!" (including the quotation
+marks!), followed by the text remembered as $2. This produces an exact copy of
+the original string, with the middle part (the "document.referrer") replaced by
+"Not Your Business!".
+
+The whole job now reads: Replace "document.referrer" by "Not Your Business!"
+wherever it appears inside a <script> tag. Note that this job won't break
+JavaScript syntax, since both the original and the replacement are
+syntactically valid string objects. The script just won't have access to the
+referrer information anymore.
+
+We'll show you two other jobs from the JavaScript taming department, but this
+time only point out the constructs of special interest:
+
+# The status bar is for displaying link targets, not pointless blahblah
+#
+s/window\.status\s*=\s*(['"]).*?\1/dUmMy=1/ig
+
+\s stands for whitespace characters (space, tab, newline, carriage return, form
+feed), so that \s* means: "zero or more whitespace". The ? in .*? makes this
+matching of arbitrary text ungreedy. (Note that the U option is not set). The
+['"] construct means: "a single or a double quote". Finally, \1 is a
+back-reference to the first parenthesis just like $1 above, with the difference
+that in the pattern, a backslash indicates a back-reference, whereas in the
+substitute, it's the dollar.
+
+So what does this job do? It replaces assignments of single- or double-quoted
+strings to the "window.status" object with a dummy assignment (using a variable
+name that is hopefully odd enough not to conflict with real variables in
+scripts). Thus, it catches many cases where e.g. pointless descriptions are
+displayed in the status bar instead of the link target when you move your mouse
+over links.
+
+# Kill OnUnload popups. Yummy. Test: http://www.zdnet.com/zdsubs/yahoo/tree/yfs.html
+#
+s/(<body [^>]*)onunload(.*>)/$1never$2/iU
+
+Including the OnUnload event binding in the HTML DOM was a CRIME. When I close
+a browser window, I want it to close and die. Basta. This job replaces the
+"onunload" attribute in "<body>" tags with the dummy word never. Note that the
+i option makes the pattern matching case-insensitive. Also note that ungreedy
+matching alone doesn't always guarantee a minimal match: In the first
+parenthesis, we had to use [^>]* instead of .* to prevent the match from
+exceeding the <body> tag if it doesn't contain "OnUnload", but the page's
+content does.
+
+The last example is from the fun department:
+
+FILTER: fun Fun text replacements
+
+# Spice the daily news:
+#
+s/microsoft(?!\.com)/MicroSuck/ig
+
+Note the (?!\.com) part (a so-called negative lookahead) in the job's pattern,
+which means: Don't match, if the string ".com" appears directly following
+"microsoft" in the page. This prevents links to microsoft.com from being
+trashed, while still replacing the word everywhere else.
+
+# Buzzword Bingo (example for extended regex syntax)
+#
+s* industry[ -]leading \
+| cutting[ -]edge \
+| customer[ -]focused \
+| market[ -]driven \
+| award[ -]winning # Comments are OK, too! \
+| high[ -]performance \
+| solutions[ -]based \
+| unmatched \
+| unparalleled \
+| unrivalled \
+*<font color="red"><b>BINGO!</b></font> \
+*igx
+
+The x option in this job turns on extended syntax, and allows for e.g. the
+liberal use of (non-interpreted!) whitespace for nicer formatting.
+
+You get the idea?
+
+-------------------------------------------------------------------------------
+
+9.2. The Pre-defined Filters
+
+The distribution default.filter file contains a selection of pre-defined
+filters for your convenience:
+
+js-annoyances
+
+ The purpose of this filter is to get rid of particularly annoying
+ JavaScript abuse. To that end, it
+
+ + replaces JavaScript references to the browser's referrer information
+ with the string "Not Your Business!". This compliments the
+ hide-referrer action on the content level.
+
+ + removes the bindings to the DOM's unload event which we feel has no
+ right to exist and is responsible for most "exit consoles", i.e. nasty
+ windows that pop up when you close another one.
+
+ + removes code that causes new windows to be opened with undesired
+ properties, such as being full-screen, non-resizeable, without
+ location, status or menu bar etc.
+
+js-events
+
+ This is a very radical measure. It removes virtually all JavaScript event
+ bindings, which means that scripts can not react to user actions such as
+ mouse movements or clicks, window resizing etc, anymore.
+
+ We strongly discourage using this filter as a default since it breaks many
+ legitimate scripts. It is meant for use only on extra-nasty sites (should
+ you really need to go there).
+
+html-annoyances
+
+ This filter will undo many common instances of HTML based abuse.
+
+ The BLINK and MARQUEE tags are neutralized (yeah baby!), and browser
+ windows will be created as resizeable (as of course they should be!), and
+ will have location, scroll and menu bars -- even if specified otherwise.
+
+content-cookies
+
+ Most cookies are set in the HTTP dialog, where they can be intercepted by
+ the crunch-incoming-cookies and crunch-outgoing-cookies actions. But web
+ sites increasingly make use of HTML meta tags and JavaScript to sneak
+ cookies to the browser on the content level.
+
+ This filter disables HTML and JavaScript code that reads or sets cookies.
+ Use it wherever you would also use the cookie crunch actions.
+
+refresh tags
+
+ Disable any refresh tags if the interval is greater than nine seconds (so
+ that redirections done via refresh tags are not destroyed). This is useful
+ for dial-on-demand setups, or for those who find this HTML feature
+ annoying.
+
+unsolicited-popups
+
+ This filter attempts to prevent only "unsolicited" pop-up windows from
+ opening, yet still allow pop-up windows that the user has explicitly chosen
+ to open. It was added in version 3.0.1, as an improvement over earlier such
+ filters.
+
+ Technical note: The filter works by redefining the window.open JavaScript
+ function to a dummy function during the loading and rendering phase of each
+ HTML page access, and restoring the function afterward.
+
+all-popups
+
+ Attempt to prevent all pop-up windows from opening. Note this should be
+ used with more discretion than the above, since it is more likely to break
+ some sites that require pop-ups for normal usage. Use with caution.
+
+img-reorder
+
+ This is a helper filter that has no value if used alone. It makes the
+ banners-by-size and banners-by-link (see below) filters more effective and
+ should be enabled together with them.
+
+banners-by-size
+
+ This filter removes image tags purely based on what size they are.
+ Fortunately for us, many ads and banner images tend to conform to certain
+ standardized sizes, which makes this filter quite effective for ad
+ stripping purposes.
+
+ Occasionally this filter will cause false positives on images that are not
+ ads, but just happen to be of one of the standard banner sizes.
+
+banners-by-link
+
+ This is an experimental filter that attempts to kill any banners if their
+ URLs seem to point to known or suspected click trackers. It is currently
+ not of much value and is not recommended for use by default.
+
+webbugs
+
+ Webbugs are small, invisible images (technically 1X1 GIF images), that are
+ used to track users across websites, and collect information on them. As an
+ HTML page is loaded by the browser, an embedded image tag causes the
+ browser to contact a third-party site, disclosing the tracking information
+ through the requested URL and/or cookies for that third-party domain,
+ without the use ever becoming aware of the interaction with the third-party
+ site. HTML-ized spam also uses a similar technique to verify email
+ addresses.
+
+ This filter removes the HTML code that loads such "webbugs".
+
+tiny-textforms
+
+ A rather special-purpose filter that can be used to enlarge textareas
+ (those multi-line text boxes in web forms) and turn off hard word wrap in
+ them. It was written for the sourceforge.net tracker system where such
+ boxes are a nuisance, but it can be handy on other sites, too.
+
+ It is not recommended to use this filter as a default.
+
+jumping-windows
+
+ Many consider windows that move, or resize themselves to be abusive. This
+ filter neutralizes the related JavaScript code. Note that some sites might
+ not display or behave as intended when using this filter.
+
+frameset-borders
+
+ Some web designers seem to assume that everyone in the world will view
+ their web sites using the same browser brand and version, screen resolution
+ etc, because only that assumption could explain why they'd use static frame
+ sizes, yet prevent their frames from being resized by the user, should they
+ be too small to show their whole content.
+
+ This filter removes the related HTML code. It should only be applied to
+ sites which need it.
+
+demoronizer
+
+ Many Microsoft products that generate HTML use non-standard extensions
+ (read: violations) of the ISO 8859-1 aka Latin-1 character set. This can
+ cause those HTML documents to display with errors on standard-compliant
+ platforms.
+
+ This filter translates the MS-only characters into Latin-1 equivalents. It
+ is not necessary when using MS products, and will cause corruption of all
+ documents that use 8-bit character sets other than Latin-1. It's mostly
+ worthwhile for Europeans on non-MS platforms, if weird garbage characters
+ sometimes appear on some pages, or user agents that don't correct for this
+ on the fly.
+
+shockwave-flash
+
+ A filter for shockwave haters. As the name suggests, this filter strips
+ code out of web pages that is used to embed shockwave flash objects.
+
+quicktime-kioskmode
+
+ Change HTML code that embeds Quicktime objects so that kioskmode, which
+ prevents saving, is disabled.
+
+fun
+
+ Text replacements for subversive browsing fun. Make fun of your favorite
+ Monopolist or play buzzword bingo.
+
+crude-parental
+
+ A demonstration-only filter that shows how Privoxy can be used to delete
+ web content on a keyword basis.
+
+ie-exploits
+
+ A collection of text replacements to disable malicious HTML and JavaScript
+ code that exploits known security holes in Internet Explorer.
+
+ Presently, it only protects against Nimda and a cross-site scripting bug,
+ and would need active maintenance to provide more substantial protection.
+
+site-specifics
+
+ Some web sites have very specific problems, the cure for which doesn't
+ apply anywhere else, or could even cause damage on other sites.
+
+ This is a collection of such site-specific cures which should only be
+ applied to the sites they were intended for, which is what the supplied
+ default.action file does. Users shouldn't need to change anything regarding
+ this filter.
+
+-------------------------------------------------------------------------------
+
+10. Privoxy's Template Files
+
+All Privoxy built-in pages, i.e. error pages such as the "404 - No Such Domain"
+error page, the "BLOCKED" page and all pages of its web-based user interface,
+are generated from templates. (Privoxy must be running for the above links to
+work as intended.)
+
+These templates are stored in a subdirectory of the configuration directory
+called templates. On Unixish platforms, this is typically /etc/privoxy/
+templates/.
+
+The templates are basically normal HTML files, but with place-holders (called
+symbols or exports), which Privoxy fills at run time. You can edit the
+templates with a normal text editor, should you want to customize them. (Not
+recommended for the casual user). Note that just like in configuration files,
+lines starting with # are ignored when the templates are filled in.
+
+The place-holders are of the form @name@, and you will find a list of available
+symbols, which vary from template to template, in the comments at the start of
+each file. Note that these comments are not always accurate, and that it's
+probably best to look at the existing HTML code to find out which symbols are
+supported and what they are filled in with.
+
+A special application of this substitution mechanism is to make whole blocks of
+HTML code disappear when a specific symbol is set. We use this for many
+purposes, one of them being to include the beta warning in all our user
+interface (CGI) pages when Privoxy is in an alpha or beta development stage:
+
+<!-- @if-unstable-start -->
+
+ ... beta warning HTML code goes here ...
+
+<!-- if-unstable-end@ -->
+
+If the "unstable" symbol is set, everything in between and including
+@if-unstable-start and if-unstable-end@ will disappear, leaving nothing but an
+empty comment:
+
+<!-- -->
+
+There's also an if-then-else construct and an #include mechanism, but you'll
+sure find out if you are inclined to edit the templates ;-)
+
+All templates refer to a style located at http://config.privoxy.org/
+send-stylesheet. This is, of course, locally served by Privoxy and the source
+for it can be found and edited in the cgi-style.css template.
+
+-------------------------------------------------------------------------------
+
+11. Contacting the Developers, Bug Reporting and Feature Requests
+
+We value your feedback. In fact, we rely on it to improve Privoxy and its
+configuration. However, please note the following hints, so we can provide you
+with the best support:
+
+-------------------------------------------------------------------------------
+
+11.1. Get Support
+
+For casual users, our support forum at SourceForge is probably best suited:
+http://sourceforge.net/tracker/?group_id=11118&atid=211118
+
+All users are of course welcome to discuss their issues on the users mailing
+list, where the developers also hang around.
+
+-------------------------------------------------------------------------------
+
+11.2. Reporting Problems
+
+"Problems" for our purposes, come in two forms:
+
+ * Configuration issues, such as ads that slip through, or sites that don't
+ function properly due to one Privoxy "action" or another being turned "on".
+
+ * "Bugs" in the programming code that makes up Privoxy, such as that might
+ cause a crash.
+
+-------------------------------------------------------------------------------
+
+11.2.1. Reporting Ads or Other Configuration Problems
+
+Please send feedback on ads that slipped through, innocent images that were
+blocked, sites that don't work properly, and other configuration related
+problem of default.action file, to http://sourceforge.net/tracker/?group_id=
+11118&atid=460288, the Actions File Tracker.
+
+New, improved default.action files may occasionally be made available based on
+your feedback. These will be announced on the ijbswa-announce list and
+available from our the files section of our project page.
+
+-------------------------------------------------------------------------------
+
+11.2.2. Reporting Bugs
+
+Please report all bugs only through our bug tracker: http://sourceforge.net/
+tracker/?group_id=11118&atid=111118.
+
+Before doing so, please make sure that the bug has not already been submitted
+and observe the additional hints at the top of the submit form. If already
+submitted, please feel free to add any info to the original report that might
+help to solve the issue.
+
+Please try to verify that it is a Privoxy bug, and not a browser or site bug
+first. If unsure, try toggling off Privoxy, and see if the problem persists. If
+you are using your own custom configuration, please try the stock configs to
+see if the problem is configuration related.
+
+If not using the latest version, the bug may have been found and fixed in the
+meantime. We would appreciate if you could take the time to upgrade to the
+latest version (or even the latest CVS snapshot) and verify your bug.
+
+Please be sure to provide the following information:
+
+ * The exact Privoxy version of the proxy software (if you got the source from
+ CVS, please also provide the source code revisions as shown in http://
+ config.privoxy.org/show-version).
+
+ * The operating system and versions you run Privoxy on, (e.g. Windows XP
+ SP2), if you are using some kind of Unix flavour, sending the output of
+ "uname -a" should do.
+
+ * The name, platform, and version of the browser you were using (e.g.
+ Internet Explorer v5.5 for Mac).
+
+ * The URL where the problem occurred, or some way for us to duplicate the
+ problem (e.g. http://somesite.example.com/?somethingelse=123).
+
+ * Whether your version of Privoxy is one supplied by the developers of
+ Privoxy via SourceForge, or somewhere else.
+
+ * Whether you are using Privoxy in tandem with another proxy such as Tor. If
+ so, please try disabling the other proxy.
+
+ * Whether you are using a personal firewall product. If so, does Privoxy work
+ without it?
+
+ * Any other pertinent information to help identify the problem such as config
+ or log file excerpts (yes, you should have log file entries for each action
+ taken).
+
+ * Please provide your SF login, or email address, in case we need to contact
+ you.
+
+The appendix of the Privoxy User Manual also has helpful information on
+understanding actions, and action debugging.
+
+-------------------------------------------------------------------------------
+
+11.3. Request New Features
+
+You are welcome to submit ideas on new features or other proposals for
+improvement through our feature request tracker at http://sourceforge.net/
+tracker/?atid=361118&group_id=11118.
+
+-------------------------------------------------------------------------------
+
+11.4. Other
+
+For any other issues, feel free to use the mailing lists. Technically
+interested users and people who wish to contribute to the project are also
+welcome on the developers list! You can find an overview of all Privoxy-related
+mailing lists, including list archives, at: http://sourceforge.net/mail/?
+group_id=11118.
+
+-------------------------------------------------------------------------------
+
+12. Privoxy Copyright, License and History
+
+Copyright © 2001 - 2006 by Privoxy Developers <
+ijbswa-developers@lists.sourceforge.net>
+
+Some source code is based on code Copyright © 1997 by Anonymous Coders and
+Junkbusters, Inc. and licensed under the GNU General Public License.
+
+-------------------------------------------------------------------------------
+
+12.1. License
+
+Privoxy is free software; you can redistribute it and/or modify it under the
+terms of the GNU General Public License, version 2, as published by the Free
+Software Foundation.
+
+This program is distributed in the hope that it will be useful, but WITHOUT ANY
+WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A
+PARTICULAR PURPOSE. See the GNU General Public License for more details, which
+is available from the Free Software Foundation, Inc, 51 Franklin Street, Fifth
+Floor, Boston, MA 02110-1301, USA
+
+You should have received a copy of the GNU General Public License along with
+this program; if not, write to the
+
+ Free Software
+ Foundation, Inc. 51 Franklin Street, Fifth Floor
+ Boston, MA 02110-1301
+ USA
+
+-------------------------------------------------------------------------------
+
+12.2. History
+
+Along time ago, there was the Internet Junkbuster, by Anonymous Coders and
+Junkbusters Corporation. This saved many users a lot of pain in the early days
+of web advertising and user tracking.
+
+But the web, its protocols and standards, and with it, the techniques for
+forcing ads on users, give up autonomy over their browsing, and for tracking
+them, keeps evolving. Unfortunately, the Internet Junkbuster did not. Version
+2.0.2, published in 1998, was (and is) the last official release available from
+Junkbusters Corporation. Fortunately, it had been released under the GNU GPL,
+which allowed further development by others.
+
+So Stefan Waldherr started maintaining an improved version of the software, to
+which eventually a number of people contributed patches. It could already
+replace banners with a transparent image, and had a first version of pop-up
+killing, but it was still very closely based on the original, with all its
+limitations, such as the lack of HTTP/1.1 support, flexible per-site
+configuration, or content modification. The last release from this effort was
+version 2.0.2-10, published in 2000.
+
+Then, some developers picked up the thread, and started turning the software
+inside out, upside down, and then reassembled it, adding many new features
+along the way.
+
+The result of this is Privoxy, whose first stable version, 3.0, was released
+August, 2002.
+
+-------------------------------------------------------------------------------
+
+12.3. Authors
+
+Current Privoxy Team:
+
+ Fabian Keil, developer
+ David Schmidt, developer
+
+ Hal Burgiss
+ Ian Cummings
+ Félix Rauch
+ Roland Rosenfeld
+
+Former Privoxy Team Members:
+
+ Johny Agotnes
+ Rodrigo Barbosa
+ Moritz Barsnick
+ Brian Dessent
+ Jon Foster
+ Karsten Hopp
+ Alexander Lazic
+ Daniel Leite
+ Gábor Lipták
+ Adam Lock
+ Guy Laroche
+ Mark Martinec
+ Andreas Oesterhelt
+ Haroon Rafique
+ Georg Sauthoff
+ Thomas Steudten
+ Joerg Strohmayer
+ Rodney Stromlund
+ Sviatoslav Sviridov
+ Sarantis Paskalis
+ Stefan Waldherr
+
+Thanks to the many people who have tested Privoxy, reported bugs, made
+suggestions or contributed in some way. These include (in alphabetical order):
+
+ Ken Arromdee
+ Devin Bayer
+ Reiner Buehl
+ Andrew J. Caines
+ Clifford Caoile
+ Michael T. Davis
+ Mattes Dolak
+ Ulrich Drepper
+ Peter E
+ Aaron Hamid
+ Magnus Holmgren
+ Don Libes
+ Paul Lieverse
+ Jindrich Makovicka
+ David Mediavilla
+ Oliver Stoeneberg
+ Roberto Ragusa
+ Maynard Riley
+ Bart Schelstraete
+ Bobby G. Vinyard
+ Darren Wiebe
+ Jörg Weinmann
+ Oliver Yeoh
+ Jamie Zawinski
+
+Privoxy is based in part on code originally developed by:
+
+ Junkbusters Corp.
+ Anonymous Coders
+
+-------------------------------------------------------------------------------
+
+13. See Also
+
+Other references and sites of interest to Privoxy users:
+
+http://www.privoxy.org/, the Privoxy Home page.
+
+http://www.privoxy.org/faq/, the Privoxy FAQ.
+
+http://sourceforge.net/projects/ijbswa/, the Project Page for Privoxy on
+SourceForge.
+
+http://config.privoxy.org/, the web-based user interface. Privoxy must be
+running for this to work. Shortcut: http://p.p/
+
+http://sourceforge.net/tracker/?group_id=11118&atid=460288, to submit "misses"
+and other configuration related suggestions to the developers.
+
+http://www.junkbusters.com/ht/en/cookies.html, an explanation how cookies are
+used to track web users.
+
+http://www.junkbusters.com/ijb.html, the original Internet Junkbuster.
+
+http://privacy.net/, a useful site to check what information about you is
+leaked while you browse the web.
+
+http://www.squid-cache.org/, a very popular caching proxy, which is often used
+together with Privoxy.
+
+http://tor.eff.org/, Tor can help anonymize web browsing, web publishing,
+instant messaging, IRC, SSH, and other applications.
+
+http://www.privoxy.org/developer-manual/, the Privoxy developer manual.
+
+-------------------------------------------------------------------------------
+
+14. Appendix
+
+14.1. Regular Expressions
+
+Privoxy uses Perl-style "regular expressions" in its actions files and filter
+file, through the PCRE and PCRS libraries.
+
+If you are reading this, you probably don't understand what "regular
+expressions" are, or what they can do. So this will be a very brief
+introduction only. A full explanation would require a book ;-)
+
+Regular expressions provide a language to describe patterns that can be run
+against strings of characters (letter, numbers, etc), to see if they match the
+string or not. The patterns are themselves (sometimes complex) strings of
+literal characters, combined with wild-cards, and other special characters,
+called meta-characters. The "meta-characters" have special meanings and are
+used to build complex patterns to be matched against. Perl Compatible Regular
+Expressions are an especially convenient "dialect" of the regular expression
+language.
+
+To make a simple analogy, we do something similar when we use wild-card
+characters when listing files with the dir command in DOS. *.* matches all
+filenames. The "special" character here is the asterisk which matches any and
+all characters. We can be more specific and use ? to match just individual
+characters. So "dir file?.text" would match "file1.txt", "file2.txt", etc. We
+are pattern matching, using a similar technique to "regular expressions"!
+
+Regular expressions do essentially the same thing, but are much, much more
+powerful. There are many more "special characters" and ways of building complex
+patterns however. Let's look at a few of the common ones, and then some
+examples:
+
+. - Matches any single character, e.g. "a", "A", "4", ":", or "@".
+
+? - The preceding character or expression is matched ZERO or ONE times. Either/
+or.
+
++ - The preceding character or expression is matched ONE or MORE times.
+
+* - The preceding character or expression is matched ZERO or MORE times.
+
+\ - The "escape" character denotes that the following character should be taken
+literally. This is used where one of the special characters (e.g. ".") needs to
+be taken literally and not as a special meta-character. Example: "example
+\.com", makes sure the period is recognized only as a period (and not expanded
+to its meta-character meaning of any single character).
+
+[ ] - Characters enclosed in brackets will be matched if any of the enclosed
+characters are encountered. For instance, "[0-9]" matches any numeric digit
+(zero through nine). As an example, we can combine this with "+" to match any
+digit one of more times: "[0-9]+".
+
+( ) - parentheses are used to group a sub-expression, or multiple
+sub-expressions.
+
+| - The "bar" character works like an "or" conditional statement. A match is
+successful if the sub-expression on either side of "|" matches. As an example:
+"/(this|that) example/" uses grouping and the bar character and would match
+either "this example" or "that example", and nothing else.
+
+These are just some of the ones you are likely to use when matching URLs with
+Privoxy, and is a long way from a definitive list. This is enough to get us
+started with a few simple examples which may be more illuminating:
+
+/.*/banners/.* - A simple example that uses the common combination of "." and "
+*" to denote any character, zero or more times. In other words, any string at
+all. So we start with a literal forward slash, then our regular expression
+pattern (".*") another literal forward slash, the string "banners", another
+forward slash, and lastly another ".*". We are building a directory path here.
+This will match any file with the path that has a directory named "banners" in
+it. The ".*" matches any characters, and this could conceivably be more forward
+slashes, so it might expand into a much longer looking path. For example, this
+could match: "/eye/hate/spammers/banners/annoy_me_please.gif", or just "/
+banners/annoying.html", or almost an infinite number of other possible
+combinations, just so it has "banners" in the path somewhere.
+
+And now something a little more complex:
+
+/.*/adv((er)?ts?|ertis(ing|ements?))?/ - We have several literal forward
+slashes again ("/"), so we are building another expression that is a file path
+statement. We have another ".*", so we are matching against any conceivable
+sub-path, just so it matches our expression. The only true literal that must
+match our pattern is adv, together with the forward slashes. What comes after
+the "adv" string is the interesting part.
+
+Remember the "?" means the preceding expression (either a literal character or
+anything grouped with "(...)" in this case) can exist or not, since this means
+either zero or one match. So "((er)?ts?|ertis(ing|ements?))" is optional, as
+are the individual sub-expressions: "(er)", "(ing|ements?)", and the "s". The "
+|" means "or". We have two of those. For instance, "(ing|ements?)", can expand
+to match either "ing" OR "ements?". What is being done here, is an attempt at
+matching as many variations of "advertisement", and similar, as possible. So
+this would expand to match just "adv", or "advert", or "adverts", or
+"advertising", or "advertisement", or "advertisements". You get the idea. But
+it would not match "advertizements" (with a "z"). We could fix that by changing
+our regular expression to: "/.*/adv((er)?ts?|erti(s|z)(ing|ements?))?/", which
+would then match either spelling.
+
+/.*/advert[0-9]+\.(gif|jpe?g) - Again another path statement with forward
+slashes. Anything in the square brackets "[ ]" can be matched. This is using
+"0-9" as a shorthand expression to mean any digit one through nine. It is the
+same as saying "0123456789". So any digit matches. The "+" means one or more of
+the preceding expression must be included. The preceding expression here is
+what is in the square brackets -- in this case, any digit one through nine.
+Then, at the end, we have a grouping: "(gif|jpe?g)". This includes a "|", so
+this needs to match the expression on either side of that bar character also. A
+simple "gif" on one side, and the other side will in turn match either "jpeg"
+or "jpg", since the "?" means the letter "e" is optional and can be matched
+once or not at all. So we are building an expression here to match image GIF or
+JPEG type image file. It must include the literal string "advert", then one or
+more digits, and a "." (which is now a literal, and not a special character,
+since it is escaped with "\"), and lastly either "gif", or "jpeg", or "jpg".
+Some possible matches would include: "//advert1.jpg", "/nasty/ads/
+advert1234.gif", "/banners/from/hell/advert99.jpg". It would not match
+"advert1.gif" (no leading slash), or "/adverts232.jpg" (the expression does not
+include an "s"), or "/advert1.jsp" ("jsp" is not in the expression anywhere).
+
+We are barely scratching the surface of regular expressions here so that you
+can understand the default Privoxy configuration files, and maybe use this
+knowledge to customize your own installation. There is much, much more that can
+be done with regular expressions. Now that you know enough to get started, you
+can learn more on your own :/
+
+More reading on Perl Compatible Regular expressions: http://perldoc.perl.org/
+perlre.html
+
+For information on regular expression based substitutions and their
+applications in filters, please see the filter file tutorial in this manual.
+
+-------------------------------------------------------------------------------
+
+14.2. Privoxy's Internal Pages
+
+Since Privoxy proxies each requested web page, it is easy for Privoxy to trap
+certain special URLs. In this way, we can talk directly to Privoxy, and see how
+it is configured, see how our rules are being applied, change these rules and
+other configuration options, and even turn Privoxy's filtering off, all with a
+web browser.
+
+The URLs listed below are the special ones that allow direct access to Privoxy.
+Of course, Privoxy must be running to access these. If not, you will get a
+friendly error message. Internet access is not necessary either.
+
+ * Privoxy main page:
+
+ http://config.privoxy.org/
+
+ There is a shortcut: http://p.p/ (But it doesn't provide a fall-back to a
+ real page, in case the request is not sent through Privoxy)
+
+ * Show information about the current configuration, including viewing and
+ editing of actions files:
+
+ http://config.privoxy.org/show-status
+
+ * Show the source code version numbers:
+
+ http://config.privoxy.org/show-version
+
+ * Show the browser's request headers:
+
+ http://config.privoxy.org/show-request
+
+ * Show which actions apply to a URL and why:
+
+ http://config.privoxy.org/show-url-info
+
+ * Toggle Privoxy on or off. In this case, "Privoxy" continues to run, but
+ only as a pass-through proxy, with no actions taking place:
+
+ http://config.privoxy.org/toggle
+
+ Short cuts. Turn off, then on:
+
+ http://config.privoxy.org/toggle?set=disable
+
+ http://config.privoxy.org/toggle?set=enable
+
+These may be bookmarked for quick reference. See next.
+
+-------------------------------------------------------------------------------
+
+14.2.1. Bookmarklets
+
+Below are some "bookmarklets" to allow you to easily access a "mini" version of
+some of Privoxy's special pages. They are designed for MS Internet Explorer,
+but should work equally well in Netscape, Mozilla, and other browsers which
+support JavaScript. They are designed to run directly from your bookmarks - not
+by clicking the links below (although that should work for testing).
+
+To save them, right-click the link and choose "Add to Favorites" (IE) or "Add
+Bookmark" (Netscape). You will get a warning that the bookmark "may not be
+safe" - just click OK. Then you can run the Bookmarklet directly from your
+favorites/bookmarks. For even faster access, you can put them on the "Links"
+bar (IE) or the "Personal Toolbar" (Netscape), and run them with a single
+click.
+
+ * Privoxy - Enable
+
+ * Privoxy - Disable
+
+ * Privoxy - Toggle Privoxy (Toggles between enabled and disabled)
+
+ * Privoxy- View Status
+
+ * Privoxy - Why?
+
+Credit: The site which gave us the general idea for these bookmarklets is
+www.bookmarklets.com. They have more information about bookmarklets.
+
+-------------------------------------------------------------------------------
+
+14.3. Chain of Events
+
+Let's take a quick look at the basic sequence of events when a web page is
+requested by your browser and Privoxy is on duty:
+
+ * First, your web browser requests a web page. The browser knows to send the
+ request to Privoxy, which will in turn, relay the request to the remote web
+ server after passing the following tests:
+
+ * Privoxy traps any request for its own internal CGI pages (e.g http://p.p/)
+ and sends the CGI page back to the browser.
+
+ * Next, Privoxy checks to see if the URL matches any "+block" patterns. If
+ so, the URL is then blocked, and the remote web server will not be
+ contacted. "+handle-as-image" is then checked and if it does not match, an
+ HTML "BLOCKED" page is sent back. Otherwise, if it does match, an image is
+ returned. The type of image depends on the setting of "+set-image-blocker"
+ (blank, checkerboard pattern, or an HTTP redirect to an image elsewhere).
+
+ * Untrusted URLs are blocked. If URLs are being added to the trust file, then
+ that is done.
+
+ * If the URL pattern matches the "+fast-redirects" action, it is then
+ processed. Unwanted parts of the requested URL are stripped.
+
+ * Now the rest of the client browser's request headers are processed. If any
+ of these match any of the relevant actions (e.g. "+hide-user-agent", etc.),
+ headers are suppressed or forged as determined by these actions and their
+ parameters.
+
+ * Now the web server starts sending its response back (i.e. typically a web
+ page and related data).
+
+ * First, the server headers are read and processed to determine, among other
+ things, the MIME type (document type) and encoding. The headers are then
+ filtered as determined by the "+crunch-incoming-cookies",
+ "+session-cookies-only", and "+downgrade-http-version" actions.
+
+ * If the "+kill-popups" action applies, and it is an HTML or JavaScript
+ document, the popup-code in the response is filtered on-the-fly as it is
+ received.
+
+ * If a "+filter" or "+deanimate-gifs" action applies (and the document type
+ fits the action), the rest of the page is read into memory (up to a
+ configurable limit). Then the filter rules (from default.filter and any
+ other filter files) are processed against the buffered content. Filters are
+ applied in the order they are specified in one of the filter files.
+ Animated GIFs, if present, are reduced to either the first or last frame,
+ depending on the action setting.The entire page, which is now filtered, is
+ then sent by Privoxy back to your browser.
+
+ If neither "+filter" or "+deanimate-gifs" matches, then Privoxy passes the
+ raw data through to the client browser as it becomes available.
+
+ * As the browser receives the now (possibly filtered) page content, it reads
+ and then requests any URLs that may be embedded within the page source,
+ e.g. ad images, stylesheets, JavaScript, other HTML documents (e.g.
+ frames), sounds, etc. For each of these objects, the browser issues a new
+ request. And each such request is in turn processed as above. Note that a
+ complex web page may have many such embedded URLs.
+
+-------------------------------------------------------------------------------
+
+14.4. Troubleshooting: Anatomy of an Action
+
+The way Privoxy applies actions and filters to any given URL can be complex,
+and not always so easy to understand what is happening. And sometimes we need
+to be able to see just what Privoxy is doing. Especially, if something Privoxy
+is doing is causing us a problem inadvertently. It can be a little daunting to
+look at the actions and filters files themselves, since they tend to be filled
+with regular expressions whose consequences are not always so obvious.
+
+One quick test to see if Privoxy is causing a problem or not, is to disable it
+temporarily. This should be the first troubleshooting step. See the
+Bookmarklets section on a quick and easy way to do this (be sure to flush
+caches afterward!). Looking at the logs is a good idea too.
+
+Another easy troubleshooting step to try is if you have done any customization
+of your installation, revert back to the installed defaults and see if that
+helps. There are times the developers get complaints about one thing or
+another, and the problem is more related to a customized configuration issue.
+
+Privoxy also provides the http://config.privoxy.org/show-url-info page that can
+show us very specifically how actions are being applied to any given URL. This
+is a big help for troubleshooting.
+
+First, enter one URL (or partial URL) at the prompt, and then Privoxy will tell
+us how the current configuration will handle it. This will not help with
+filtering effects (i.e. the "+filter" action) from one of the filter files
+since this is handled very differently and not so easy to trap! It also will
+not tell you about any other URLs that may be embedded within the URL you are
+testing. For instance, images such as ads are expressed as URLs within the raw
+page source of HTML pages. So you will only get info for the actual URL that is
+pasted into the prompt area -- not any sub-URLs. If you want to know about
+embedded URLs like ads, you will have to dig those out of the HTML source. Use
+your browser's "View Page Source" option for this. Or right click on the ad,
+and grab the URL.
+
+Let's try an example, google.com, and look at it one section at a time in a
+sample configuration (your real configuration may vary):
+
+ Matches for http://google.com:
+
+ In file: default.action [ View ] [ Edit ]
+
+ {-add-header
+ -block
+ -content-type-overwrite
+ -crunch-client-header
+ -crunch-if-none-match
+ -crunch-incoming-cookies
+ -crunch-outgoing-cookies
+ -crunch-server-header
+ +deanimate-gifs {last}
+ -downgrade-http-version
+ +fast-redirects {check-decoded-url}
+ -filter {js-events}
+ -filter {content-cookies}
+ -filter {all-popups}
+ -filter {banners-by-link}
+ -filter {tiny-textforms}
+ -filter {frameset-borders}
+ -filter {demoronizer}
+ -filter {shockwave-flash}
+ -filter {quicktime-kioskmode}
+ -filter {fun}
+ -filter {crude-parental}
+ -filter {site-specifics}
+ +filter {js-annoyances}
+ +filter {html-annoyances}
+ +filter {refresh-tags}
+ +filter {unsolicited-popups}
+ +filter {img-reorder}
+ +filter {banners-by-size}
+ +filter {webbugs}
+ +filter {jumping-windows}
+ +filter {ie-exploits}
+ -filter-client-headers
+ -filter-server-headers
+ -force-text-mode
+ -handle-as-empty-document
+ -handle-as-image
+ -hide-accept-language
+ -hide-content-disposition
+ +hide-forwarded-for-headers
+ +hide-from-header {block}
+ -hide-if-modified-since
+ +hide-referrer {forge}
+ -hide-user-agent
+ -inspect-jpegs
+ -kill-popups
+ -limit-connect
+ -overwrite-last-modified
+ +prevent-compression
+ -redirect
+ -send-vanilla-wafer
+ -send-wafer
+ +session-cookies-only
+ +set-image-blocker {pattern}
+ -treat-forbidden-connects-like-blocks }
+/
+
+ { -session-cookies-only }
+ .google.com
+
+ { -fast-redirects }
+ .google.com
+
+In file: user.action [ View ] [ Edit ]
+(no matches in this file)
+
+This is telling us how we have defined our "actions", and which ones match for
+our test case, "google.com". Displayed is all the actions that are available to
+us. Remember, the + sign denotes "on". - denotes "off". So some are "on" here,
+but many are "off". Each example we try may provide a slightly different end
+result, depending on our configuration directives.
+
+The first listing is for our default.action file. The large, multi-line
+listing, is how the actions are set to match for all URLs, i.e. our default
+settings. If you look at your "actions" file, this would be the section just
+below the "aliases" section near the top. This will apply to all URLs as
+signified by the single forward slash at the end of the listing -- " / ".
+
+But we have defined additional actions that would be exceptions to these
+general rules, and then we list specific URLs (or patterns) that these
+exceptions would apply to. Last match wins. Just below this then are two
+explicit matches for ".google.com". The first is negating our previous cookie
+setting, which was for "+session-cookies-only" (i.e. not persistent). So we
+will allow persistent cookies for google, at least that is how it is in this
+example. The second turns off any "+fast-redirects" action, allowing this to
+take place unmolested. Note that there is a leading dot here -- ".google.com".
+This will match any hosts and sub-domains, in the google.com domain also, such
+as "www.google.com" or "mail.google.com". But it would not match
+"www.google.de"! So, apparently, we have these two actions defined as
+exceptions to the general rules at the top somewhere in the lower part of our
+default.action file, and "google.com" is referenced somewhere in these latter
+sections.
+
+Then, for our user.action file, we again have no hits. So there is nothing
+google-specific that we might have added to our own, local configuration. If
+there was, those actions would over-rule any actions from previously processed
+files, such as default.action. user.action typically has the last word. This is
+the best place to put hard and fast exceptions,
+
+And finally we pull it all together in the bottom section and summarize how
+Privoxy is applying all its "actions" to "google.com":
+
+ Final results:
+
+ -add-header
+ -block
+ -content-type-overwrite
+ -crunch-client-header
+ -crunch-if-none-match
+ -crunch-incoming-cookies
+ -crunch-outgoing-cookies
+ -crunch-server-header
+ +deanimate-gifs {last}
+ -downgrade-http-version
+ -fast-redirects
+ +filter {js-annoyances}
+ +filter {html-annoyances}
+ +filter {refresh-tags}
+ +filter {unsolicited-popups}
+ +filter {img-reorder}
+ +filter {banners-by-size}
+ +filter {webbugs}
+ +filter {jumping-windows}
+ +filter {ie-exploits}
+ -filter-client-headers
+ -filter-server-headers
+ -force-text-mode
+ -handle-as-empty-document
+ -handle-as-image
+ -hide-accept-language
+ -hide-content-disposition
+ +hide-forwarded-for-headers
+ +hide-from-header {block}
+ -hide-if-modified-since
+ +hide-referrer {forge}
+ -hide-user-agent
+ -inspect-jpegs
+ -kill-popups
+ -limit-connect
+ -overwrite-last-modified
+ +prevent-compression
+ -redirect
+ -send-vanilla-wafer
+ -send-wafer
+ -session-cookies-only
+ +set-image-blocker {pattern}
+ -treat-forbidden-connects-like-blocks
+
+Notice the only difference here to the previous listing, is to "fast-redirects"
+and "session-cookies-only", which are activated specifically for this site in
+our configuration, and thus show in the "Final Results".
+
+Now another example, "ad.doubleclick.net":
+
+ { +block }
+ ad*.
+
+ { +block }
+ .ad.
+
+ { +block +handle-as-image }
+ .[a-vx-z]*.doubleclick.net
+
+We'll just show the interesting part here - the explicit matches. It is matched
+three different times. Two "+block" sections, and a "+block +handle-as-image",
+which is the expanded form of one of our aliases that had been defined as:
+"+block-as-image". ("Aliases" are defined in the first section of the actions
+file and typically used to combine more than one action.)
+
+Any one of these would have done the trick and blocked this as an unwanted
+image. This is unnecessarily redundant since the last case effectively would
+also cover the first. No point in taking chances with these guys though ;-)
+Note that if you want an ad or obnoxious URL to be invisible, it should be
+defined as "ad.doubleclick.net" is done here -- as both a "+block" and an
+"+handle-as-image". The custom alias "+block-as-image" just simplifies the
+process and make it more readable.
+
+One last example. Let's try "http://www.example.net/adsl/HOWTO/". This one is
+giving us problems. We are getting a blank page. Hmmm ...
+
+ Matches for http://www.example.net/adsl/HOWTO/:
+
+ In file: default.action [ View ] [ Edit ]
+
+ {-add-header
+ -block
+ -content-type-overwrite
+ -crunch-client-header
+ -crunch-if-none-match
+ -crunch-incoming-cookies
+ -crunch-outgoing-cookies
+ -crunch-server-header
+ +deanimate-gifs
+ -downgrade-http-version
+ +fast-redirects{check-decoded-url}
+ +filter{html-annoyances}
+ +filter{js-annoyances}
+ +filter{kill-popups}
+ +filter{webbugs}
+ +filter{nimda}
+ +filter{banners-by-size}
+ +filter{hal}
+ +filter{fun}
+ -filter-client-headers
+ -filter-server-headers
+ -force-text-mode
+ -handle-as-empty-document
+ -handle-as-image
+ -hide-accept-language
+ -hide-content-disposition
+ +hide-forwarded-for-headers
+ +hide-from-header{block}
+ +hide-referer{forge}
+ -hide-user-agent
+ -inspect-jpegs
+ +kill-popups
+ -overwrite-last-modified
+ +prevent-compression
+ -redirect
+ -send-vanilla-wafer
+ -send-wafer
+ +session-cookies-only
+ +set-image-blocker{blank}
+ -treat-forbidden-connects-like-blocks }
+ /
+
+ { +block +handle-as-image }
+ /ads
+
+Ooops, the "/adsl/" is matching "/ads" in our configuration! But we did not
+want this at all! Now we see why we get the blank page. It is actually
+triggering two different actions here, and the effects are aggregated so that
+the URL is blocked, and Privoxy is told to treat the block as if it were an
+image. But this is, of course, all wrong. We could now add a new action below
+this (or better in our own user.action file) that explicitly un blocks ( "
+{-block}") paths with "adsl" in them (remember, last match in the configuration
+wins). There are various ways to handle such exceptions. Example:
+
+ { -block }
+ /adsl
+
+Now the page displays ;-) Remember to flush your browser's caches when making
+these kinds of changes to your configuration to insure that you get a freshly
+delivered page! Or, try using Shift+Reload.
+
+But now what about a situation where we get no explicit matches like we did
+with:
+
+ { +block +handle-as-image }
+ /ads
+
+That actually was very helpful and pointed us quickly to where the problem was.
+If you don't get this kind of match, then it means one of the default rules in
+the first section of default.action is causing the problem. This would require
+some guesswork, and maybe a little trial and error to isolate the offending
+rule. One likely cause would be one of the "+filter" actions. These tend to be
+harder to troubleshoot. Try adding the URL for the site to one of aliases that
+turn off "+filter":
+
+ { shop }
+ .quietpc.com
+ .worldpay.com # for quietpc.com
+ .jungle.com
+ .scan.co.uk
+ .forbes.com
+
+"{ shop }" is an "alias" that expands to "{ -filter -session-cookies-only }".
+Or you could do your own exception to negate filtering:
+
+ { -filter }
+ # Disable ALL filter actions for sites in this section
+ .forbes.com
+ developer.ibm.com
+ localhost
+
+This would turn off all filtering for these sites. This is best put in
+user.action, for local site exceptions. Note that when a simple domain pattern
+is used by itself (without the subsequent path portion), all sub-pages within
+that domain are included automatcially in the scope of the action.
+
+Images that are inexplicably being blocked, may well be hitting the "+filter
+{banners-by-size}" rule, which assumes that images of certain sizes are ad
+banners (works well most of the time since these tend to be standardized).
+
+"{ fragile }" is an alias that disables most actions that are the most likely
+to cause trouble. This can be used as a last resort for problem sites.
+
+ { fragile }
+ # Handle with care: easy to break
+ mail.google.
+ mybank.example.com
+
+Remember to flush caches! Note that the mail.google reference lacks the TLD
+portion (e.g. ".com". This will effectively match any TLD with google in it,
+such as mail.google.de, just as an example.
+
+If this still does not work, you will have to go through the remaining actions
+one by one to find which one(s) is causing the problem.
+