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->Privoxy 3.0.18 User Manual</TH
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-><DIV
-CLASS="SECT1"
-><H1
-CLASS="SECT1"
-><A
-NAME="APPENDIX"
->14. Appendix</A
-></H1
-><DIV
-CLASS="SECT2"
-><H2
-CLASS="SECT2"
-><A
-NAME="REGEX"
->14.1. Regular Expressions</A
-></H2
-><P
-> <SPAN
-CLASS="APPLICATION"
->Privoxy</SPAN
-> uses Perl-style <SPAN
-CLASS="QUOTE"
->"regular
- expressions"</SPAN
-> in its <A
-HREF="actions-file.html"
->actions
- files</A
-> and <A
-HREF="filter-file.html"
->filter file</A
->,
- through the <A
-HREF="http://www.pcre.org/"
-TARGET="_top"
->PCRE</A
-> and
- <SPAN
-CLASS="APPLICATION"
->PCRS</SPAN
-> libraries.</P
-><P
-> If you are reading this, you probably don't understand what <SPAN
-CLASS="QUOTE"
->"regular
- expressions"</SPAN
-> are, or what they can do. So this will be a very brief
- introduction only. A full explanation would require a <A
-HREF="http://www.oreilly.com/catalog/regex/"
-TARGET="_top"
->book</A
-> ;-)</P
-><P
-> 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 <SPAN
-CLASS="QUOTE"
->"meta-characters"</SPAN
-> have
- special meanings and are used to build complex patterns to be matched against.
- Perl Compatible Regular Expressions are an especially convenient
- <SPAN
-CLASS="QUOTE"
->"dialect"</SPAN
-> of the regular expression language.</P
-><P
-> To make a simple analogy, we do something similar when we use wild-card
- characters when listing files with the <B
-CLASS="COMMAND"
->dir</B
-> command in DOS.
- <TT
-CLASS="LITERAL"
->*.*</TT
-> matches all filenames. The <SPAN
-CLASS="QUOTE"
->"special"</SPAN
->
- character here is the asterisk which matches any and all characters. We can be
- more specific and use <TT
-CLASS="LITERAL"
->?</TT
-> to match just individual
- characters. So <SPAN
-CLASS="QUOTE"
->"dir file?.text"</SPAN
-> would match
- <SPAN
-CLASS="QUOTE"
->"file1.txt"</SPAN
->, <SPAN
-CLASS="QUOTE"
->"file2.txt"</SPAN
->, etc. We are pattern
- matching, using a similar technique to <SPAN
-CLASS="QUOTE"
->"regular expressions"</SPAN
->!</P
-><P
-> Regular expressions do essentially the same thing, but are much, much more
- powerful. There are many more <SPAN
-CLASS="QUOTE"
->"special characters"</SPAN
-> and ways of
- building complex patterns however. Let's look at a few of the common ones,
- and then some examples:</P
-><P
-><P
-></P
-><TABLE
-BORDER="0"
-><TBODY
-><TR
-><TD
-> <SPAN
-CLASS="emphasis"
-><I
-CLASS="EMPHASIS"
->.</I
-></SPAN
-> - Matches any single character, e.g. <SPAN
-CLASS="QUOTE"
->"a"</SPAN
->,
- <SPAN
-CLASS="QUOTE"
->"A"</SPAN
->, <SPAN
-CLASS="QUOTE"
->"4"</SPAN
->, <SPAN
-CLASS="QUOTE"
->":"</SPAN
->, or <SPAN
-CLASS="QUOTE"
->"@"</SPAN
->.
- </TD
-></TR
-></TBODY
-></TABLE
-><P
-></P
-></P
-><P
-><P
-></P
-><TABLE
-BORDER="0"
-><TBODY
-><TR
-><TD
-> <SPAN
-CLASS="emphasis"
-><I
-CLASS="EMPHASIS"
->?</I
-></SPAN
-> - The preceding character or expression is matched ZERO or ONE
- times. Either/or.
- </TD
-></TR
-></TBODY
-></TABLE
-><P
-></P
-></P
-><P
-><P
-></P
-><TABLE
-BORDER="0"
-><TBODY
-><TR
-><TD
-> <SPAN
-CLASS="emphasis"
-><I
-CLASS="EMPHASIS"
->+</I
-></SPAN
-> - The preceding character or expression is matched ONE or MORE
- times.
- </TD
-></TR
-></TBODY
-></TABLE
-><P
-></P
-></P
-><P
-><P
-></P
-><TABLE
-BORDER="0"
-><TBODY
-><TR
-><TD
-> <SPAN
-CLASS="emphasis"
-><I
-CLASS="EMPHASIS"
->*</I
-></SPAN
-> - The preceding character or expression is matched ZERO or MORE
- times.
- </TD
-></TR
-></TBODY
-></TABLE
-><P
-></P
-></P
-><P
-><P
-></P
-><TABLE
-BORDER="0"
-><TBODY
-><TR
-><TD
-> <SPAN
-CLASS="emphasis"
-><I
-CLASS="EMPHASIS"
->\</I
-></SPAN
-> - The <SPAN
-CLASS="QUOTE"
->"escape"</SPAN
-> character denotes that
- the following character should be taken literally. This is used where one of the
- special characters (e.g. <SPAN
-CLASS="QUOTE"
->"."</SPAN
->) needs to be taken literally and
- not as a special meta-character. Example: <SPAN
-CLASS="QUOTE"
->"example\.com"</SPAN
->, makes
- sure the period is recognized only as a period (and not expanded to its
- meta-character meaning of any single character).
- </TD
-></TR
-></TBODY
-></TABLE
-><P
-></P
-></P
-><P
-><P
-></P
-><TABLE
-BORDER="0"
-><TBODY
-><TR
-><TD
-> <SPAN
-CLASS="emphasis"
-><I
-CLASS="EMPHASIS"
->[ ]</I
-></SPAN
-> - Characters enclosed in brackets will be matched if
- any of the enclosed characters are encountered. For instance, <SPAN
-CLASS="QUOTE"
->"[0-9]"</SPAN
->
- matches any numeric digit (zero through nine). As an example, we can combine
- this with <SPAN
-CLASS="QUOTE"
->"+"</SPAN
-> to match any digit one of more times: <SPAN
-CLASS="QUOTE"
->"[0-9]+"</SPAN
->.
- </TD
-></TR
-></TBODY
-></TABLE
-><P
-></P
-></P
-><P
-><P
-></P
-><TABLE
-BORDER="0"
-><TBODY
-><TR
-><TD
-> <SPAN
-CLASS="emphasis"
-><I
-CLASS="EMPHASIS"
->( )</I
-></SPAN
-> - parentheses are used to group a sub-expression,
- or multiple sub-expressions.
- </TD
-></TR
-></TBODY
-></TABLE
-><P
-></P
-></P
-><P
-><P
-></P
-><TABLE
-BORDER="0"
-><TBODY
-><TR
-><TD
-> <SPAN
-CLASS="emphasis"
-><I
-CLASS="EMPHASIS"
->|</I
-></SPAN
-> - The <SPAN
-CLASS="QUOTE"
->"bar"</SPAN
-> character works like an
- <SPAN
-CLASS="QUOTE"
->"or"</SPAN
-> conditional statement. A match is successful if the
- sub-expression on either side of <SPAN
-CLASS="QUOTE"
->"|"</SPAN
-> matches. As an example:
- <SPAN
-CLASS="QUOTE"
->"/(this|that) example/"</SPAN
-> uses grouping and the bar character
- and would match either <SPAN
-CLASS="QUOTE"
->"this example"</SPAN
-> or <SPAN
-CLASS="QUOTE"
->"that
- example"</SPAN
->, and nothing else.
- </TD
-></TR
-></TBODY
-></TABLE
-><P
-></P
-></P
-><P
-> These are just some of the ones you are likely to use when matching URLs with
- <SPAN
-CLASS="APPLICATION"
->Privoxy</SPAN
->, 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:</P
-><P
-> <SPAN
-CLASS="emphasis"
-><I
-CLASS="EMPHASIS"
-><TT
-CLASS="LITERAL"
->/.*/banners/.*</TT
-></I
-></SPAN
-> - A simple example
- that uses the common combination of <SPAN
-CLASS="QUOTE"
->"."</SPAN
-> and <SPAN
-CLASS="QUOTE"
->"*"</SPAN
-> 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
- (<SPAN
-CLASS="QUOTE"
->".*"</SPAN
->) another literal forward slash, the string
- <SPAN
-CLASS="QUOTE"
->"banners"</SPAN
->, another forward slash, and lastly another
- <SPAN
-CLASS="QUOTE"
->".*"</SPAN
->. We are building
- a directory path here. This will match any file with the path that has a
- directory named <SPAN
-CLASS="QUOTE"
->"banners"</SPAN
-> in it. The <SPAN
-CLASS="QUOTE"
->".*"</SPAN
-> 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:
- <SPAN
-CLASS="QUOTE"
->"/eye/hate/spammers/banners/annoy_me_please.gif"</SPAN
->, or just
- <SPAN
-CLASS="QUOTE"
->"/banners/annoying.html"</SPAN
->, or almost an infinite number of other
- possible combinations, just so it has <SPAN
-CLASS="QUOTE"
->"banners"</SPAN
-> in the path
- somewhere.</P
-><P
-> And now something a little more complex:</P
-><P
-> <SPAN
-CLASS="emphasis"
-><I
-CLASS="EMPHASIS"
-><TT
-CLASS="LITERAL"
->/.*/adv((er)?ts?|ertis(ing|ements?))?/</TT
-></I
-></SPAN
-> -
- We have several literal forward slashes again (<SPAN
-CLASS="QUOTE"
->"/"</SPAN
->), so we are
- building another expression that is a file path statement. We have another
- <SPAN
-CLASS="QUOTE"
->".*"</SPAN
->, so we are matching against any conceivable sub-path, just so
- it matches our expression. The only true literal that <SPAN
-CLASS="emphasis"
-><I
-CLASS="EMPHASIS"
->must
- match</I
-></SPAN
-> our pattern is <SPAN
-CLASS="APPLICATION"
->adv</SPAN
->, together with
- the forward slashes. What comes after the <SPAN
-CLASS="QUOTE"
->"adv"</SPAN
-> string is the
- interesting part. </P
-><P
-> Remember the <SPAN
-CLASS="QUOTE"
->"?"</SPAN
-> means the preceding expression (either a
- literal character or anything grouped with <SPAN
-CLASS="QUOTE"
->"(...)"</SPAN
-> in this case)
- can exist or not, since this means either zero or one match. So
- <SPAN
-CLASS="QUOTE"
->"((er)?ts?|ertis(ing|ements?))"</SPAN
-> is optional, as are the
- individual sub-expressions: <SPAN
-CLASS="QUOTE"
->"(er)"</SPAN
->,
- <SPAN
-CLASS="QUOTE"
->"(ing|ements?)"</SPAN
->, and the <SPAN
-CLASS="QUOTE"
->"s"</SPAN
->. The <SPAN
-CLASS="QUOTE"
->"|"</SPAN
->
- means <SPAN
-CLASS="QUOTE"
->"or"</SPAN
->. We have two of those. For instance,
- <SPAN
-CLASS="QUOTE"
->"(ing|ements?)"</SPAN
->, can expand to match either <SPAN
-CLASS="QUOTE"
->"ing"</SPAN
->
- <SPAN
-CLASS="emphasis"
-><I
-CLASS="EMPHASIS"
->OR</I
-></SPAN
-> <SPAN
-CLASS="QUOTE"
->"ements?"</SPAN
->. What is being done here, is an
- attempt at matching as many variations of <SPAN
-CLASS="QUOTE"
->"advertisement"</SPAN
->, and
- similar, as possible. So this would expand to match just <SPAN
-CLASS="QUOTE"
->"adv"</SPAN
->,
- or <SPAN
-CLASS="QUOTE"
->"advert"</SPAN
->, or <SPAN
-CLASS="QUOTE"
->"adverts"</SPAN
->, or
- <SPAN
-CLASS="QUOTE"
->"advertising"</SPAN
->, or <SPAN
-CLASS="QUOTE"
->"advertisement"</SPAN
->, or
- <SPAN
-CLASS="QUOTE"
->"advertisements"</SPAN
->. You get the idea. But it would not match
- <SPAN
-CLASS="QUOTE"
->"advertizements"</SPAN
-> (with a <SPAN
-CLASS="QUOTE"
->"z"</SPAN
->). We could fix that by
- changing our regular expression to:
- <SPAN
-CLASS="QUOTE"
->"/.*/adv((er)?ts?|erti(s|z)(ing|ements?))?/"</SPAN
->, which would then match
- either spelling.</P
-><P
-> <SPAN
-CLASS="emphasis"
-><I
-CLASS="EMPHASIS"
-><TT
-CLASS="LITERAL"
->/.*/advert[0-9]+\.(gif|jpe?g)</TT
-></I
-></SPAN
-> - Again
- another path statement with forward slashes. Anything in the square brackets
- <SPAN
-CLASS="QUOTE"
->"[ ]"</SPAN
-> can be matched. This is using <SPAN
-CLASS="QUOTE"
->"0-9"</SPAN
-> as a
- shorthand expression to mean any digit one through nine. It is the same as
- saying <SPAN
-CLASS="QUOTE"
->"0123456789"</SPAN
->. So any digit matches. The <SPAN
-CLASS="QUOTE"
->"+"</SPAN
->
- 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: <SPAN
-CLASS="QUOTE"
->"(gif|jpe?g)"</SPAN
->.
- This includes a <SPAN
-CLASS="QUOTE"
->"|"</SPAN
->, so this needs to match the expression on
- either side of that bar character also. A simple <SPAN
-CLASS="QUOTE"
->"gif"</SPAN
-> on one side, and the other
- side will in turn match either <SPAN
-CLASS="QUOTE"
->"jpeg"</SPAN
-> or <SPAN
-CLASS="QUOTE"
->"jpg"</SPAN
->,
- since the <SPAN
-CLASS="QUOTE"
->"?"</SPAN
-> means the letter <SPAN
-CLASS="QUOTE"
->"e"</SPAN
-> 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 <SPAN
-CLASS="QUOTE"
->"advert"</SPAN
->, then one or more digits, and a <SPAN
-CLASS="QUOTE"
->"."</SPAN
->
- (which is now a literal, and not a special character, since it is escaped
- with <SPAN
-CLASS="QUOTE"
->"\"</SPAN
->), and lastly either <SPAN
-CLASS="QUOTE"
->"gif"</SPAN
->, or
- <SPAN
-CLASS="QUOTE"
->"jpeg"</SPAN
->, or <SPAN
-CLASS="QUOTE"
->"jpg"</SPAN
->. Some possible matches would
- include: <SPAN
-CLASS="QUOTE"
->"//advert1.jpg"</SPAN
->,
- <SPAN
-CLASS="QUOTE"
->"/nasty/ads/advert1234.gif"</SPAN
->,
- <SPAN
-CLASS="QUOTE"
->"/banners/from/hell/advert99.jpg"</SPAN
->. It would not match
- <SPAN
-CLASS="QUOTE"
->"advert1.gif"</SPAN
-> (no leading slash), or
- <SPAN
-CLASS="QUOTE"
->"/adverts232.jpg"</SPAN
-> (the expression does not include an
- <SPAN
-CLASS="QUOTE"
->"s"</SPAN
->), or <SPAN
-CLASS="QUOTE"
->"/advert1.jsp"</SPAN
-> (<SPAN
-CLASS="QUOTE"
->"jsp"</SPAN
-> is not
- in the expression anywhere).</P
-><P
-> We are barely scratching the surface of regular expressions here so that you
- can understand the default <SPAN
-CLASS="APPLICATION"
->Privoxy</SPAN
->
- 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 :/</P
-><P
-> More reading on Perl Compatible Regular expressions:
- <A
-HREF="http://perldoc.perl.org/perlre.html"
-TARGET="_top"
->http://perldoc.perl.org/perlre.html</A
-></P
-><P
-> For information on regular expression based substitutions and their applications
- in filters, please see the <A
-HREF="filter-file.html"
->filter file tutorial</A
->
- in this manual.</P
-></DIV
-><DIV
-CLASS="SECT2"
-><H2
-CLASS="SECT2"
-><A
-NAME="AEN5636"
->14.2. Privoxy's Internal Pages</A
-></H2
-><P
-> Since <SPAN
-CLASS="APPLICATION"
->Privoxy</SPAN
-> proxies each requested
- web page, it is easy for <SPAN
-CLASS="APPLICATION"
->Privoxy</SPAN
-> to
- trap certain special URLs. In this way, we can talk directly to
- <SPAN
-CLASS="APPLICATION"
->Privoxy</SPAN
->, and see how it is
- configured, see how our rules are being applied, change these
- rules and other configuration options, and even turn
- <SPAN
-CLASS="APPLICATION"
->Privoxy's</SPAN
-> filtering off, all with
- a web browser. </P
-><P
-> The URLs listed below are the special ones that allow direct access
- to <SPAN
-CLASS="APPLICATION"
->Privoxy</SPAN
->. Of course,
- <SPAN
-CLASS="APPLICATION"
->Privoxy</SPAN
-> must be running to access these. If
- not, you will get a friendly error message. Internet access is not
- necessary either.</P
-><P
-> <P
-></P
-><UL
-><LI
-><P
->
- Privoxy main page:
- </P
-><A
-NAME="AEN5650"
-></A
-><BLOCKQUOTE
-CLASS="BLOCKQUOTE"
-><P
->
- <A
-HREF="http://config.privoxy.org/"
-TARGET="_top"
->http://config.privoxy.org/</A
->
- </P
-></BLOCKQUOTE
-><P
-> There is a shortcut: <A
-HREF="http://p.p/"
-TARGET="_top"
->http://p.p/</A
-> (But it
- doesn't provide a fall-back to a real page, in case the request is not
- sent through <SPAN
-CLASS="APPLICATION"
->Privoxy</SPAN
->)
- </P
-></LI
-><LI
-><P
->
- Show information about the current configuration, including viewing and
- editing of actions files:
- </P
-><A
-NAME="AEN5658"
-></A
-><BLOCKQUOTE
-CLASS="BLOCKQUOTE"
-><P
->
- <A
-HREF="http://config.privoxy.org/show-status"
-TARGET="_top"
->http://config.privoxy.org/show-status</A
->
- </P
-></BLOCKQUOTE
-></LI
-><LI
-><P
->
- Show the source code version numbers:
- </P
-><A
-NAME="AEN5663"
-></A
-><BLOCKQUOTE
-CLASS="BLOCKQUOTE"
-><P
->
- <A
-HREF="http://config.privoxy.org/show-version"
-TARGET="_top"
->http://config.privoxy.org/show-version</A
->
- </P
-></BLOCKQUOTE
-></LI
-><LI
-><P
->
- Show the browser's request headers:
- </P
-><A
-NAME="AEN5668"
-></A
-><BLOCKQUOTE
-CLASS="BLOCKQUOTE"
-><P
->
- <A
-HREF="http://config.privoxy.org/show-request"
-TARGET="_top"
->http://config.privoxy.org/show-request</A
->
- </P
-></BLOCKQUOTE
-></LI
-><LI
-><P
->
- Show which actions apply to a URL and why:
- </P
-><A
-NAME="AEN5673"
-></A
-><BLOCKQUOTE
-CLASS="BLOCKQUOTE"
-><P
->
- <A
-HREF="http://config.privoxy.org/show-url-info"
-TARGET="_top"
->http://config.privoxy.org/show-url-info</A
->
- </P
-></BLOCKQUOTE
-></LI
-><LI
-><P
->
- Toggle Privoxy on or off. This feature can be turned off/on in the main
- <TT
-CLASS="FILENAME"
->config</TT
-> file. When toggled <SPAN
-CLASS="QUOTE"
->"off"</SPAN
->, <SPAN
-CLASS="QUOTE"
->"Privoxy"</SPAN
->
- continues to run, but only as a pass-through proxy, with no actions taking
- place:
- </P
-><A
-NAME="AEN5681"
-></A
-><BLOCKQUOTE
-CLASS="BLOCKQUOTE"
-><P
->
- <A
-HREF="http://config.privoxy.org/toggle"
-TARGET="_top"
->http://config.privoxy.org/toggle</A
->
- </P
-></BLOCKQUOTE
-><P
-> Short cuts. Turn off, then on:
- </P
-><A
-NAME="AEN5685"
-></A
-><BLOCKQUOTE
-CLASS="BLOCKQUOTE"
-><P
->
- <A
-HREF="http://config.privoxy.org/toggle?set=disable"
-TARGET="_top"
->http://config.privoxy.org/toggle?set=disable</A
->
- </P
-></BLOCKQUOTE
-><A
-NAME="AEN5688"
-></A
-><BLOCKQUOTE
-CLASS="BLOCKQUOTE"
-><P
->
- <A
-HREF="http://config.privoxy.org/toggle?set=enable"
-TARGET="_top"
->http://config.privoxy.org/toggle?set=enable</A
->
- </P
-></BLOCKQUOTE
-></LI
-></UL
-></P
-><P
-> These may be bookmarked for quick reference. See next. </P
-><DIV
-CLASS="SECT3"
-><H3
-CLASS="SECT3"
-><A
-NAME="BOOKMARKLETS"
->14.2.1. Bookmarklets</A
-></H3
-><P
-> Below are some <SPAN
-CLASS="QUOTE"
->"bookmarklets"</SPAN
-> to allow you to easily access a
- <SPAN
-CLASS="QUOTE"
->"mini"</SPAN
-> version of some of <SPAN
-CLASS="APPLICATION"
->Privoxy's</SPAN
->
- 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).</P
-><P
-> To save them, right-click the link and choose <SPAN
-CLASS="QUOTE"
->"Add to Favorites"</SPAN
->
- (IE) or <SPAN
-CLASS="QUOTE"
->"Add Bookmark"</SPAN
-> (Netscape). You will get a warning that
- the bookmark <SPAN
-CLASS="QUOTE"
->"may not be safe"</SPAN
-> - just click OK. Then you can run the
- Bookmarklet directly from your favorites/bookmarks. For even faster access,
- you can put them on the <SPAN
-CLASS="QUOTE"
->"Links"</SPAN
-> bar (IE) or the <SPAN
-CLASS="QUOTE"
->"Personal
- Toolbar"</SPAN
-> (Netscape), and run them with a single click. </P
-><P
-> <P
-></P
-><UL
-><LI
-><P
-> <A
-HREF="javascript:void(window.open('http://config.privoxy.org/toggle?mini=y&set=enabled','ijbstatus','width=250,height=100,resizable=yes,scrollbars=no,toolbar=no,location=no,directories=no,status=no,menubar=no,copyhistory=no').focus());"
-TARGET="_top"
->Privoxy - Enable</A
->
- </P
-></LI
-><LI
-><P
-> <A
-HREF="javascript:void(window.open('http://config.privoxy.org/toggle?mini=y&set=disabled','ijbstatus','width=250,height=100,resizable=yes,scrollbars=no,toolbar=no,location=no,directories=no,status=no,menubar=no,copyhistory=no').focus());"
-TARGET="_top"
->Privoxy - Disable</A
->
- </P
-></LI
-><LI
-><P
-> <A
-HREF="javascript:void(window.open('http://config.privoxy.org/toggle?mini=y&set=toggle','ijbstatus','width=250,height=100,resizable=yes,scrollbars=no,toolbar=no,location=no,directories=no,status=no,menubar=no,copyhistory=no').focus());"
-TARGET="_top"
->Privoxy - Toggle Privoxy</A
-> (Toggles between enabled and disabled)
- </P
-></LI
-><LI
-><P
-> <A
-HREF="javascript:void(window.open('http://config.privoxy.org/toggle?mini=y','ijbstatus','width=250,height=2,resizable=yes,scrollbars=no,toolbar=no,location=no,directories=no,status=no,menubar=no,copyhistory=no').focus());"
-TARGET="_top"
->Privoxy- View Status</A
->
- </P
-></LI
-><LI
-><P
-> <A
-HREF="javascript:void(window.open('http://config.privoxy.org/show-url-info?url='+escape(location.href),'Why').focus());"
-TARGET="_top"
->Privoxy - Why?</A
->
- </P
-></LI
-></UL
-></P
-><P
-> Credit: The site which gave us the general idea for these bookmarklets is
- <A
-HREF="http://www.bookmarklets.com/"
-TARGET="_top"
->www.bookmarklets.com</A
->. They
- have more information about bookmarklets. </P
-></DIV
-></DIV
-><DIV
-CLASS="SECT2"
-><H2
-CLASS="SECT2"
-><A
-NAME="CHAIN"
->14.3. Chain of Events</A
-></H2
-><P
-> Let's take a quick look at how some of <SPAN
-CLASS="APPLICATION"
->Privoxy's</SPAN
->
- core features are triggered, and the ensuing sequence of events when a web
- page is requested by your browser:</P
-><P
-> <P
-></P
-><UL
-><LI
-><P
-> First, your web browser requests a web page. The browser knows to send
- the request to <SPAN
-CLASS="APPLICATION"
->Privoxy</SPAN
->, which will in turn,
- relay the request to the remote web server after passing the following
- tests:
- </P
-></LI
-><LI
-><P
-> <SPAN
-CLASS="APPLICATION"
->Privoxy</SPAN
-> traps any request for its own internal CGI
- pages (e.g <A
-HREF="http://p.p/"
-TARGET="_top"
->http://p.p/</A
->) and sends the CGI page back to the browser.
- </P
-></LI
-><LI
-><P
-> Next, <SPAN
-CLASS="APPLICATION"
->Privoxy</SPAN
-> checks to see if the URL
- matches any <A
-HREF="actions-file.html#BLOCK"
-><SPAN
-CLASS="QUOTE"
->"+block"</SPAN
-></A
-> patterns. If
- so, the URL is then blocked, and the remote web server will not be contacted.
- <A
-HREF="actions-file.html#HANDLE-AS-IMAGE"
-><SPAN
-CLASS="QUOTE"
->"+handle-as-image"</SPAN
-></A
->
- and
- <A
-HREF="actions-file.html#HANDLE-AS-EMPTY-DOCUMENT"
-><SPAN
-CLASS="QUOTE"
->"+handle-as-empty-document"</SPAN
-></A
->
- are then checked, and if there is no match, an
- HTML <SPAN
-CLASS="QUOTE"
->"BLOCKED"</SPAN
-> page is sent back to the browser. Otherwise, if
- it does match, an image is returned for the former, and an empty text
- document for the latter. The type of image would depend on the setting of
- <A
-HREF="actions-file.html#SET-IMAGE-BLOCKER"
-><SPAN
-CLASS="QUOTE"
->"+set-image-blocker"</SPAN
-></A
->
- (blank, checkerboard pattern, or an HTTP redirect to an image elsewhere).
- </P
-></LI
-><LI
-><P
-> Untrusted URLs are blocked. If URLs are being added to the
- <TT
-CLASS="FILENAME"
->trust</TT
-> file, then that is done.
- </P
-></LI
-><LI
-><P
-> If the URL pattern matches the <A
-HREF="actions-file.html#FAST-REDIRECTS"
-><SPAN
-CLASS="QUOTE"
->"+fast-redirects"</SPAN
-></A
-> action,
- it is then processed. Unwanted parts of the requested URL are stripped.
- </P
-></LI
-><LI
-><P
-> Now the rest of the client browser's request headers are processed. If any
- of these match any of the relevant actions (e.g. <A
-HREF="actions-file.html#HIDE-USER-AGENT"
-><SPAN
-CLASS="QUOTE"
->"+hide-user-agent"</SPAN
-></A
->,
- etc.), headers are suppressed or forged as determined by these actions and
- their parameters.
- </P
-></LI
-><LI
-><P
-> Now the web server starts sending its response back (i.e. typically a web
- page).
- </P
-></LI
-><LI
-><P
-> 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
- <A
-HREF="actions-file.html#CRUNCH-INCOMING-COOKIES"
-><SPAN
-CLASS="QUOTE"
->"+crunch-incoming-cookies"</SPAN
-></A
->,
- <A
-HREF="actions-file.html#SESSION-COOKIES-ONLY"
-><SPAN
-CLASS="QUOTE"
->"+session-cookies-only"</SPAN
-></A
->,
- and <A
-HREF="actions-file.html#DOWNGRADE-HTTP-VERSION"
-><SPAN
-CLASS="QUOTE"
->"+downgrade-http-version"</SPAN
-></A
->
- actions.
- </P
-></LI
-><LI
-><P
-> If any <A
-HREF="actions-file.html#FILTER"
-><SPAN
-CLASS="QUOTE"
->"+filter"</SPAN
-></A
-> action
- or <A
-HREF="actions-file.html#DEANIMATE-GIFS"
-><SPAN
-CLASS="QUOTE"
->"+deanimate-gifs"</SPAN
-></A
->
- 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
- <TT
-CLASS="FILENAME"
->default.filter</TT
-> 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
- <SPAN
-CLASS="APPLICATION"
->Privoxy</SPAN
-> back to your browser.
- </P
-><P
-> If neither a <A
-HREF="actions-file.html#FILTER"
-><SPAN
-CLASS="QUOTE"
->"+filter"</SPAN
-></A
-> action
- or <A
-HREF="actions-file.html#DEANIMATE-GIFS"
-><SPAN
-CLASS="QUOTE"
->"+deanimate-gifs"</SPAN
-></A
->
- matches, then <SPAN
-CLASS="APPLICATION"
->Privoxy</SPAN
-> passes the raw data through
- to the client browser as it becomes available.
- </P
-></LI
-><LI
-><P
-> 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
- separate request (this is easily viewable in <SPAN
-CLASS="APPLICATION"
->Privoxy's</SPAN
->
- logs). And each such request is in turn processed just as above. Note that a
- complex web page will have many, many such embedded URLs. If these
- secondary requests are to a different server, then quite possibly a very
- differing set of actions is triggered.
- </P
-></LI
-></UL
-></P
-><P
-> NOTE: This is somewhat of a simplistic overview of what happens with each URL
- request. For the sake of brevity and simplicity, we have focused on
- <SPAN
-CLASS="APPLICATION"
->Privoxy's</SPAN
-> core features only.</P
-></DIV
-><DIV
-CLASS="SECT2"
-><H2
-CLASS="SECT2"
-><A
-NAME="ACTIONSANAT"
->14.4. Troubleshooting: Anatomy of an Action</A
-></H2
-><P
-> The way <SPAN
-CLASS="APPLICATION"
->Privoxy</SPAN
-> applies
- <A
-HREF="actions-file.html#ACTIONS"
->actions</A
-> and <A
-HREF="actions-file.html#FILTER"
->filters</A
->
- 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
- <SPAN
-CLASS="emphasis"
-><I
-CLASS="EMPHASIS"
->see</I
-></SPAN
-> just what <SPAN
-CLASS="APPLICATION"
->Privoxy</SPAN
-> is
- doing. Especially, if something <SPAN
-CLASS="APPLICATION"
->Privoxy</SPAN
-> 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
- <A
-HREF="appendix.html#REGEX"
->regular expressions</A
-> whose consequences are not
- always so obvious. </P
-><P
-> One quick test to see if <SPAN
-CLASS="APPLICATION"
->Privoxy</SPAN
-> is causing a problem
- or not, is to disable it temporarily. This should be the first troubleshooting
- step. See <A
-HREF="appendix.html#BOOKMARKLETS"
->the Bookmarklets</A
-> 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. (Note that both the toggle feature and logging are
- enabled via <TT
-CLASS="FILENAME"
->config</TT
-> file settings, and may need to be
- turned <SPAN
-CLASS="QUOTE"
->"on"</SPAN
->.)</P
-><P
-> 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.</P
-><P
-> <SPAN
-CLASS="APPLICATION"
->Privoxy</SPAN
-> also provides the
- <A
-HREF="http://config.privoxy.org/show-url-info"
-TARGET="_top"
->http://config.privoxy.org/show-url-info</A
->
- page that can show us very specifically how <SPAN
-CLASS="APPLICATION"
->actions</SPAN
->
- are being applied to any given URL. This is a big help for troubleshooting.</P
-><P
-> First, enter one URL (or partial URL) at the prompt, and then
- <SPAN
-CLASS="APPLICATION"
->Privoxy</SPAN
-> will tell us
- how the current configuration will handle it. This will not
- help with filtering effects (i.e. the <A
-HREF="actions-file.html#FILTER"
-><SPAN
-CLASS="QUOTE"
->"+filter"</SPAN
-></A
-> 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 <SPAN
-CLASS="QUOTE"
->"View
- Page Source"</SPAN
-> option for this. Or right click on the ad, and grab the
- URL.</P
-><P
-> Let's try an example, <A
-HREF="http://google.com"
-TARGET="_top"
->google.com</A
->,
- and look at it one section at a time in a sample configuration (your real
- configuration may vary):</P
-><P
-> <TABLE
-BORDER="0"
-BGCOLOR="#E0E0E0"
-WIDTH="100%"
-><TR
-><TD
-><PRE
-CLASS="SCREEN"
-> Matches for http://www.google.com:
-
- In file: default.action <SPAN
-CLASS="GUIBUTTON"
->[ View ]</SPAN
-> <SPAN
-CLASS="GUIBUTTON"
->[ Edit ]</SPAN
->
+<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"
+"http://www.w3.org/TR/html4/loose.dtd">
+
+<html>
+<head>
+ <title>Appendix</title>
+ <meta name="GENERATOR" content=
+ "Modular DocBook HTML Stylesheet Version 1.79">
+ <link rel="HOME" title="Privoxy 3.0.25 User Manual" href="index.html">
+ <link rel="PREVIOUS" title="See Also" href="seealso.html">
+ <link rel="STYLESHEET" type="text/css" href="../p_doc.css">
+ <meta http-equiv="Content-Type" content="text/html; charset=us-ascii">
+ <link rel="STYLESHEET" type="text/css" href="p_doc.css">
+</head>
+
+<body class="SECT1" bgcolor="#EEEEEE" text="#000000" link="#0000FF" vlink=
+"#840084" alink="#0000FF">
+ <div class="NAVHEADER">
+ <table summary="Header navigation table" width="100%" border="0"
+ cellpadding="0" cellspacing="0">
+ <tr>
+ <th colspan="3" align="center">Privoxy 3.0.25 User Manual</th>
+ </tr>
+
+ <tr>
+ <td width="10%" align="left" valign="bottom"><a href="seealso.html"
+ accesskey="P">Prev</a></td>
+
+ <td width="80%" align="center" valign="bottom"></td>
+
+ <td width="10%" align="right" valign="bottom"> </td>
+ </tr>
+ </table>
+ <hr align="left" width="100%">
+ </div>
+
+ <div class="SECT1">
+ <h1 class="SECT1"><a name="APPENDIX" id="APPENDIX">14. Appendix</a></h1>
+
+ <div class="SECT2">
+ <h2 class="SECT2"><a name="REGEX" id="REGEX">14.1. Regular
+ Expressions</a></h2>
+
+ <p><span class="APPLICATION">Privoxy</span> uses Perl-style
+ <span class="QUOTE">"regular expressions"</span> in its <a href=
+ "actions-file.html">actions files</a> and <a href=
+ "filter-file.html">filter file</a>, through the <a href=
+ "http://www.pcre.org/" target="_top">PCRE</a> and <span class=
+ "APPLICATION">PCRS</span> libraries.</p>
+
+ <p>If you are reading this, you probably don't understand what
+ <span class="QUOTE">"regular expressions"</span> are, or what they can
+ do. So this will be a very brief introduction only. A full explanation
+ would require a <a href="http://www.oreilly.com/catalog/regex/" target=
+ "_top">book</a> ;-)</p>
+
+ <p>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 <span class=
+ "QUOTE">"meta-characters"</span> have special meanings and are used to
+ build complex patterns to be matched against. Perl Compatible Regular
+ Expressions are an especially convenient <span class=
+ "QUOTE">"dialect"</span> of the regular expression language.</p>
+
+ <p>To make a simple analogy, we do something similar when we use
+ wild-card characters when listing files with the <b class=
+ "COMMAND">dir</b> command in DOS. <tt class="LITERAL">*.*</tt> matches
+ all filenames. The <span class="QUOTE">"special"</span> character here
+ is the asterisk which matches any and all characters. We can be more
+ specific and use <tt class="LITERAL">?</tt> to match just individual
+ characters. So <span class="QUOTE">"dir file?.text"</span> would match
+ <span class="QUOTE">"file1.txt"</span>, <span class=
+ "QUOTE">"file2.txt"</span>, etc. We are pattern matching, using a
+ similar technique to <span class="QUOTE">"regular
+ expressions"</span>!</p>
+
+ <p>Regular expressions do essentially the same thing, but are much,
+ much more powerful. There are many more <span class="QUOTE">"special
+ characters"</span> and ways of building complex patterns however. Let's
+ look at a few of the common ones, and then some examples:</p>
+
+ <table border="0">
+ <tbody>
+ <tr>
+ <td><span class="emphasis"><i class="EMPHASIS">.</i></span> -
+ Matches any single character, e.g. <span class=
+ "QUOTE">"a"</span>, <span class="QUOTE">"A"</span>, <span class=
+ "QUOTE">"4"</span>, <span class="QUOTE">":"</span>, or
+ <span class="QUOTE">"@"</span>.</td>
+ </tr>
+ </tbody>
+ </table>
+
+ <table border="0">
+ <tbody>
+ <tr>
+ <td><span class="emphasis"><i class="EMPHASIS">?</i></span> - The
+ preceding character or expression is matched ZERO or ONE times.
+ Either/or.</td>
+ </tr>
+ </tbody>
+ </table>
+
+ <table border="0">
+ <tbody>
+ <tr>
+ <td><span class="emphasis"><i class="EMPHASIS">+</i></span> - The
+ preceding character or expression is matched ONE or MORE
+ times.</td>
+ </tr>
+ </tbody>
+ </table>
+
+ <table border="0">
+ <tbody>
+ <tr>
+ <td><span class="emphasis"><i class="EMPHASIS">*</i></span> - The
+ preceding character or expression is matched ZERO or MORE
+ times.</td>
+ </tr>
+ </tbody>
+ </table>
+
+ <table border="0">
+ <tbody>
+ <tr>
+ <td><span class="emphasis"><i class="EMPHASIS">\</i></span> - The
+ <span class="QUOTE">"escape"</span> character denotes that the
+ following character should be taken literally. This is used where
+ one of the special characters (e.g. <span class=
+ "QUOTE">"."</span>) needs to be taken literally and not as a
+ special meta-character. Example: <span class=
+ "QUOTE">"example\.com"</span>, makes sure the period is
+ recognized only as a period (and not expanded to its
+ meta-character meaning of any single character).</td>
+ </tr>
+ </tbody>
+ </table>
+
+ <table border="0">
+ <tbody>
+ <tr>
+ <td><span class="emphasis"><i class="EMPHASIS">[ ]</i></span> -
+ Characters enclosed in brackets will be matched if any of the
+ enclosed characters are encountered. For instance, <span class=
+ "QUOTE">"[0-9]"</span> matches any numeric digit (zero through
+ nine). As an example, we can combine this with <span class=
+ "QUOTE">"+"</span> to match any digit one of more times:
+ <span class="QUOTE">"[0-9]+"</span>.</td>
+ </tr>
+ </tbody>
+ </table>
+
+ <table border="0">
+ <tbody>
+ <tr>
+ <td><span class="emphasis"><i class="EMPHASIS">( )</i></span> -
+ parentheses are used to group a sub-expression, or multiple
+ sub-expressions.</td>
+ </tr>
+ </tbody>
+ </table>
+
+ <table border="0">
+ <tbody>
+ <tr>
+ <td><span class="emphasis"><i class="EMPHASIS">|</i></span> - The
+ <span class="QUOTE">"bar"</span> character works like an
+ <span class="QUOTE">"or"</span> conditional statement. A match is
+ successful if the sub-expression on either side of <span class=
+ "QUOTE">"|"</span> matches. As an example: <span class=
+ "QUOTE">"/(this|that) example/"</span> uses grouping and the bar
+ character and would match either <span class="QUOTE">"this
+ example"</span> or <span class="QUOTE">"that example"</span>, and
+ nothing else.</td>
+ </tr>
+ </tbody>
+ </table>
+
+ <p>These are just some of the ones you are likely to use when matching
+ URLs with <span class="APPLICATION">Privoxy</span>, 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:</p>
+
+ <p><span class="emphasis"><i class="EMPHASIS"><tt class=
+ "LITERAL">/.*/banners/.*</tt></i></span> - A simple example that uses
+ the common combination of <span class="QUOTE">"."</span> and
+ <span class="QUOTE">"*"</span> 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 (<span class=
+ "QUOTE">".*"</span>) another literal forward slash, the string
+ <span class="QUOTE">"banners"</span>, another forward slash, and lastly
+ another <span class="QUOTE">".*"</span>. We are building a directory
+ path here. This will match any file with the path that has a directory
+ named <span class="QUOTE">"banners"</span> in it. The <span class=
+ "QUOTE">".*"</span> 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: <span class=
+ "QUOTE">"/eye/hate/spammers/banners/annoy_me_please.gif"</span>, or
+ just <span class="QUOTE">"/banners/annoying.html"</span>, or almost an
+ infinite number of other possible combinations, just so it has
+ <span class="QUOTE">"banners"</span> in the path somewhere.</p>
+
+ <p>And now something a little more complex:</p>
+
+ <p><span class="emphasis"><i class="EMPHASIS"><tt class=
+ "LITERAL">/.*/adv((er)?ts?|ertis(ing|ements?))?/</tt></i></span> - We
+ have several literal forward slashes again (<span class=
+ "QUOTE">"/"</span>), so we are building another expression that is a
+ file path statement. We have another <span class="QUOTE">".*"</span>,
+ so we are matching against any conceivable sub-path, just so it matches
+ our expression. The only true literal that <span class=
+ "emphasis"><i class="EMPHASIS">must match</i></span> our pattern is
+ <span class="APPLICATION">adv</span>, together with the forward
+ slashes. What comes after the <span class="QUOTE">"adv"</span> string
+ is the interesting part.</p>
+
+ <p>Remember the <span class="QUOTE">"?"</span> means the preceding
+ expression (either a literal character or anything grouped with
+ <span class="QUOTE">"(...)"</span> in this case) can exist or not,
+ since this means either zero or one match. So <span class=
+ "QUOTE">"((er)?ts?|ertis(ing|ements?))"</span> is optional, as are the
+ individual sub-expressions: <span class="QUOTE">"(er)"</span>,
+ <span class="QUOTE">"(ing|ements?)"</span>, and the <span class=
+ "QUOTE">"s"</span>. The <span class="QUOTE">"|"</span> means
+ <span class="QUOTE">"or"</span>. We have two of those. For instance,
+ <span class="QUOTE">"(ing|ements?)"</span>, can expand to match either
+ <span class="QUOTE">"ing"</span> <span class="emphasis"><i class=
+ "EMPHASIS">OR</i></span> <span class="QUOTE">"ements?"</span>. What is
+ being done here, is an attempt at matching as many variations of
+ <span class="QUOTE">"advertisement"</span>, and similar, as possible.
+ So this would expand to match just <span class="QUOTE">"adv"</span>, or
+ <span class="QUOTE">"advert"</span>, or <span class=
+ "QUOTE">"adverts"</span>, or <span class="QUOTE">"advertising"</span>,
+ or <span class="QUOTE">"advertisement"</span>, or <span class=
+ "QUOTE">"advertisements"</span>. You get the idea. But it would not
+ match <span class="QUOTE">"advertizements"</span> (with a <span class=
+ "QUOTE">"z"</span>). We could fix that by changing our regular
+ expression to: <span class=
+ "QUOTE">"/.*/adv((er)?ts?|erti(s|z)(ing|ements?))?/"</span>, which
+ would then match either spelling.</p>
+
+ <p><span class="emphasis"><i class="EMPHASIS"><tt class=
+ "LITERAL">/.*/advert[0-9]+\.(gif|jpe?g)</tt></i></span> - Again another
+ path statement with forward slashes. Anything in the square brackets
+ <span class="QUOTE">"[ ]"</span> can be matched. This is using
+ <span class="QUOTE">"0-9"</span> as a shorthand expression to mean any
+ digit one through nine. It is the same as saying <span class=
+ "QUOTE">"0123456789"</span>. So any digit matches. The <span class=
+ "QUOTE">"+"</span> 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: <span class="QUOTE">"(gif|jpe?g)"</span>. This
+ includes a <span class="QUOTE">"|"</span>, so this needs to match the
+ expression on either side of that bar character also. A simple
+ <span class="QUOTE">"gif"</span> on one side, and the other side will
+ in turn match either <span class="QUOTE">"jpeg"</span> or <span class=
+ "QUOTE">"jpg"</span>, since the <span class="QUOTE">"?"</span> means
+ the letter <span class="QUOTE">"e"</span> 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 <span class="QUOTE">"advert"</span>, then one or more digits,
+ and a <span class="QUOTE">"."</span> (which is now a literal, and not a
+ special character, since it is escaped with <span class=
+ "QUOTE">"\"</span>), and lastly either <span class=
+ "QUOTE">"gif"</span>, or <span class="QUOTE">"jpeg"</span>, or
+ <span class="QUOTE">"jpg"</span>. Some possible matches would include:
+ <span class="QUOTE">"//advert1.jpg"</span>, <span class=
+ "QUOTE">"/nasty/ads/advert1234.gif"</span>, <span class=
+ "QUOTE">"/banners/from/hell/advert99.jpg"</span>. It would not match
+ <span class="QUOTE">"advert1.gif"</span> (no leading slash), or
+ <span class="QUOTE">"/adverts232.jpg"</span> (the expression does not
+ include an <span class="QUOTE">"s"</span>), or <span class=
+ "QUOTE">"/advert1.jsp"</span> (<span class="QUOTE">"jsp"</span> is not
+ in the expression anywhere).</p>
+
+ <p>We are barely scratching the surface of regular expressions here so
+ that you can understand the default <span class=
+ "APPLICATION">Privoxy</span> 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 :/</p>
+
+ <p>More reading on Perl Compatible Regular expressions: <a href=
+ "http://perldoc.perl.org/perlre.html" target=
+ "_top">http://perldoc.perl.org/perlre.html</a></p>
+
+ <p>For information on regular expression based substitutions and their
+ applications in filters, please see the <a href=
+ "filter-file.html">filter file tutorial</a> in this manual.</p>
+ </div>
+
+ <div class="SECT2">
+ <h2 class="SECT2"><a name="INTERNAL-PAGES" id="INTERNAL-PAGES">14.2.
+ Privoxy's Internal Pages</a></h2>
+
+ <p>Since <span class="APPLICATION">Privoxy</span> proxies each
+ requested web page, it is easy for <span class=
+ "APPLICATION">Privoxy</span> to trap certain special URLs. In this way,
+ we can talk directly to <span class="APPLICATION">Privoxy</span>, and
+ see how it is configured, see how our rules are being applied, change
+ these rules and other configuration options, and even turn <span class=
+ "APPLICATION">Privoxy's</span> filtering off, all with a web
+ browser.</p>
+
+ <p>The URLs listed below are the special ones that allow direct access
+ to <span class="APPLICATION">Privoxy</span>. Of course, <span class=
+ "APPLICATION">Privoxy</span> must be running to access these. If not,
+ you will get a friendly error message. Internet access is not necessary
+ either.</p>
+
+ <ul>
+ <li>
+ <p>Privoxy main page:</p><a name="AEN5853" id="AEN5853"></a>
+
+ <blockquote class="BLOCKQUOTE">
+ <p><a href="http://config.privoxy.org/" target=
+ "_top">http://config.privoxy.org/</a></p>
+ </blockquote>
+
+ <p>There is a shortcut: <a href="http://p.p/" target=
+ "_top">http://p.p/</a> (But it doesn't provide a fall-back to a
+ real page, in case the request is not sent through <span class=
+ "APPLICATION">Privoxy</span>)</p>
+ </li>
+
+ <li>
+ <p>Show information about the current configuration, including
+ viewing and editing of actions files:</p><a name="AEN5861" id=
+ "AEN5861"></a>
+
+ <blockquote class="BLOCKQUOTE">
+ <p><a href="http://config.privoxy.org/show-status" target=
+ "_top">http://config.privoxy.org/show-status</a></p>
+ </blockquote>
+ </li>
+
+ <li>
+ <p>Show the source code version numbers:</p><a name="AEN5866" id=
+ "AEN5866"></a>
+
+ <blockquote class="BLOCKQUOTE">
+ <p><a href="http://config.privoxy.org/show-version" target=
+ "_top">http://config.privoxy.org/show-version</a></p>
+ </blockquote>
+ </li>
+
+ <li>
+ <p>Show the browser's request headers:</p><a name="AEN5871" id=
+ "AEN5871"></a>
+
+ <blockquote class="BLOCKQUOTE">
+ <p><a href="http://config.privoxy.org/show-request" target=
+ "_top">http://config.privoxy.org/show-request</a></p>
+ </blockquote>
+ </li>
+
+ <li>
+ <p>Show which actions apply to a URL and why:</p><a name="AEN5876"
+ id="AEN5876"></a>
+
+ <blockquote class="BLOCKQUOTE">
+ <p><a href="http://config.privoxy.org/show-url-info" target=
+ "_top">http://config.privoxy.org/show-url-info</a></p>
+ </blockquote>
+ </li>
+
+ <li>
+ <p>Toggle Privoxy on or off. This feature can be turned off/on in
+ the main <tt class="FILENAME">config</tt> file. When toggled
+ <span class="QUOTE">"off"</span>, <span class=
+ "QUOTE">"Privoxy"</span> continues to run, but only as a
+ pass-through proxy, with no actions taking place:</p><a name=
+ "AEN5884" id="AEN5884"></a>
+
+ <blockquote class="BLOCKQUOTE">
+ <p><a href="http://config.privoxy.org/toggle" target=
+ "_top">http://config.privoxy.org/toggle</a></p>
+ </blockquote>
+
+ <p>Short cuts. Turn off, then on:</p><a name="AEN5888" id=
+ "AEN5888"></a>
+
+ <blockquote class="BLOCKQUOTE">
+ <p><a href="http://config.privoxy.org/toggle?set=disable" target=
+ "_top">http://config.privoxy.org/toggle?set=disable</a></p>
+ </blockquote><a name="AEN5891" id="AEN5891"></a>
+
+ <blockquote class="BLOCKQUOTE">
+ <p><a href="http://config.privoxy.org/toggle?set=enable" target=
+ "_top">http://config.privoxy.org/toggle?set=enable</a></p>
+ </blockquote>
+ </li>
+ </ul>
+ </div>
+
+ <div class="SECT2">
+ <h2 class="SECT2"><a name="CHAIN" id="CHAIN">14.3. Chain of
+ Events</a></h2>
+
+ <p>Let's take a quick look at how some of <span class=
+ "APPLICATION">Privoxy's</span> core features are triggered, and the
+ ensuing sequence of events when a web page is requested by your
+ browser:</p>
+
+ <ul>
+ <li>
+ <p>First, your web browser requests a web page. The browser knows
+ to send the request to <span class="APPLICATION">Privoxy</span>,
+ which will in turn, relay the request to the remote web server
+ after passing the following tests:</p>
+ </li>
+
+ <li>
+ <p><span class="APPLICATION">Privoxy</span> traps any request for
+ its own internal CGI pages (e.g <a href="http://p.p/" target=
+ "_top">http://p.p/</a>) and sends the CGI page back to the
+ browser.</p>
+ </li>
+
+ <li>
+ <p>Next, <span class="APPLICATION">Privoxy</span> checks to see if
+ the URL matches any <a href="actions-file.html#BLOCK"><span class=
+ "QUOTE">"+block"</span></a> patterns. If so, the URL is then
+ blocked, and the remote web server will not be contacted. <a href=
+ "actions-file.html#HANDLE-AS-IMAGE"><span class=
+ "QUOTE">"+handle-as-image"</span></a> and <a href=
+ "actions-file.html#HANDLE-AS-EMPTY-DOCUMENT"><span class=
+ "QUOTE">"+handle-as-empty-document"</span></a> are then checked,
+ and if there is no match, an HTML <span class=
+ "QUOTE">"BLOCKED"</span> page is sent back to the browser.
+ Otherwise, if it does match, an image is returned for the former,
+ and an empty text document for the latter. The type of image would
+ depend on the setting of <a href=
+ "actions-file.html#SET-IMAGE-BLOCKER"><span class=
+ "QUOTE">"+set-image-blocker"</span></a> (blank, checkerboard
+ pattern, or an HTTP redirect to an image elsewhere).</p>
+ </li>
+
+ <li>
+ <p>Untrusted URLs are blocked. If URLs are being added to the
+ <tt class="FILENAME">trust</tt> file, then that is done.</p>
+ </li>
+
+ <li>
+ <p>If the URL pattern matches the <a href=
+ "actions-file.html#FAST-REDIRECTS"><span class=
+ "QUOTE">"+fast-redirects"</span></a> action, it is then processed.
+ Unwanted parts of the requested URL are stripped.</p>
+ </li>
+
+ <li>
+ <p>Now the rest of the client browser's request headers are
+ processed. If any of these match any of the relevant actions (e.g.
+ <a href="actions-file.html#HIDE-USER-AGENT"><span class=
+ "QUOTE">"+hide-user-agent"</span></a>, etc.), headers are
+ suppressed or forged as determined by these actions and their
+ parameters.</p>
+ </li>
+
+ <li>
+ <p>Now the web server starts sending its response back (i.e.
+ typically a web page).</p>
+ </li>
+
+ <li>
+ <p>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 <a href=
+ "actions-file.html#CRUNCH-INCOMING-COOKIES"><span class=
+ "QUOTE">"+crunch-incoming-cookies"</span></a>, <a href=
+ "actions-file.html#SESSION-COOKIES-ONLY"><span class=
+ "QUOTE">"+session-cookies-only"</span></a>, and <a href=
+ "actions-file.html#DOWNGRADE-HTTP-VERSION"><span class=
+ "QUOTE">"+downgrade-http-version"</span></a> actions.</p>
+ </li>
+
+ <li>
+ <p>If any <a href="actions-file.html#FILTER"><span class=
+ "QUOTE">"+filter"</span></a> action or <a href=
+ "actions-file.html#DEANIMATE-GIFS"><span class=
+ "QUOTE">"+deanimate-gifs"</span></a> 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
+ <tt class="FILENAME">default.filter</tt> 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 <span class=
+ "APPLICATION">Privoxy</span> back to your browser.</p>
+
+ <p>If neither a <a href="actions-file.html#FILTER"><span class=
+ "QUOTE">"+filter"</span></a> action or <a href=
+ "actions-file.html#DEANIMATE-GIFS"><span class=
+ "QUOTE">"+deanimate-gifs"</span></a> matches, then <span class=
+ "APPLICATION">Privoxy</span> passes the raw data through to the
+ client browser as it becomes available.</p>
+ </li>
+
+ <li>
+ <p>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 separate request (this is easily
+ viewable in <span class="APPLICATION">Privoxy's</span> logs). And
+ each such request is in turn processed just as above. Note that a
+ complex web page will have many, many such embedded URLs. If these
+ secondary requests are to a different server, then quite possibly a
+ very differing set of actions is triggered.</p>
+ </li>
+ </ul>
+
+ <p>NOTE: This is somewhat of a simplistic overview of what happens with
+ each URL request. For the sake of brevity and simplicity, we have
+ focused on <span class="APPLICATION">Privoxy's</span> core features
+ only.</p>
+ </div>
+
+ <div class="SECT2">
+ <h2 class="SECT2"><a name="ACTIONSANAT" id="ACTIONSANAT">14.4.
+ Troubleshooting: Anatomy of an Action</a></h2>
+
+ <p>The way <span class="APPLICATION">Privoxy</span> applies <a href=
+ "actions-file.html#ACTIONS">actions</a> and <a href=
+ "actions-file.html#FILTER">filters</a> 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 <span class="emphasis"><i class=
+ "EMPHASIS">see</i></span> just what <span class=
+ "APPLICATION">Privoxy</span> is doing. Especially, if something
+ <span class="APPLICATION">Privoxy</span> 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
+ <a href="appendix.html#REGEX">regular expressions</a> whose
+ consequences are not always so obvious.</p>
+
+ <p>One quick test to see if <span class="APPLICATION">Privoxy</span> is
+ causing a problem or not, is to disable it temporarily. This should be
+ the first troubleshooting step (be sure to flush caches afterward!).
+ Looking at the logs is a good idea too. (Note that both the toggle
+ feature and logging are enabled via <tt class="FILENAME">config</tt>
+ file settings, and may need to be turned <span class=
+ "QUOTE">"on"</span>.)</p>
+
+ <p>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.</p>
+
+ <p><span class="APPLICATION">Privoxy</span> also provides the <a href=
+ "http://config.privoxy.org/show-url-info" target=
+ "_top">http://config.privoxy.org/show-url-info</a> page that can show
+ us very specifically how <span class="APPLICATION">actions</span> are
+ being applied to any given URL. This is a big help for
+ troubleshooting.</p>
+
+ <p>First, enter one URL (or partial URL) at the prompt, and then
+ <span class="APPLICATION">Privoxy</span> will tell us how the current
+ configuration will handle it. This will not help with filtering effects
+ (i.e. the <a href="actions-file.html#FILTER"><span class=
+ "QUOTE">"+filter"</span></a> 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 <span class=
+ "QUOTE">"View Page Source"</span> option for this. Or right click on
+ the ad, and grab the URL.</p>
+
+ <p>Let's try an example, <a href="http://google.com" target=
+ "_top">google.com</a>, and look at it one section at a time in a sample
+ configuration (your real configuration may vary):</p>
+
+ <table border="0" bgcolor="#E0E0E0" width="100%">
+ <tr>
+ <td>
+ <pre class="SCREEN">
+ Matches for http://www.google.com:
+
+ In file: default.action <span class="GUIBUTTON">[ View ]</span> <span class=
+"GUIBUTTON">[ Edit ]</span>
{+change-x-forwarded-for{block}
+deanimate-gifs {last}
+session-cookies-only
+set-image-blocker {pattern}
/
-
+
{ -session-cookies-only }
.google.com
{ -fast-redirects }
.google.com
-In file: user.action <SPAN
-CLASS="GUIBUTTON"
->[ View ]</SPAN
-> <SPAN
-CLASS="GUIBUTTON"
->[ Edit ]</SPAN
->
-(no matches in this file) </PRE
-></TD
-></TR
-></TABLE
-></P
-><P
-> This is telling us how we have defined our
- <A
-HREF="actions-file.html#ACTIONS"
-><SPAN
-CLASS="QUOTE"
->"actions"</SPAN
-></A
->, and
- which ones match for our test case, <SPAN
-CLASS="QUOTE"
->"google.com"</SPAN
->.
- Displayed is all the actions that are available to us. Remember,
- the <TT
-CLASS="LITERAL"
->+</TT
-> sign denotes <SPAN
-CLASS="QUOTE"
->"on"</SPAN
->. <TT
-CLASS="LITERAL"
->-</TT
->
- denotes <SPAN
-CLASS="QUOTE"
->"off"</SPAN
->. So some are <SPAN
-CLASS="QUOTE"
->"on"</SPAN
-> here, but many
- are <SPAN
-CLASS="QUOTE"
->"off"</SPAN
->. Each example we try may provide a slightly different
- end result, depending on our configuration directives.</P
-><P
-> The first listing
- is for our <TT
-CLASS="FILENAME"
->default.action</TT
-> 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 <SPAN
-CLASS="QUOTE"
->"actions"</SPAN
-> file, this would be the
- section just below the <SPAN
-CLASS="QUOTE"
->"aliases"</SPAN
-> section near the top. This
- will apply to all URLs as signified by the single forward slash at the end
- of the listing -- <SPAN
-CLASS="QUOTE"
->" / "</SPAN
->.</P
-><P
-> 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 <SPAN
-CLASS="QUOTE"
->".google.com"</SPAN
->. The first is negating our previous
- cookie setting, which was for <A
-HREF="actions-file.html#SESSION-COOKIES-ONLY"
-><SPAN
-CLASS="QUOTE"
->"+session-cookies-only"</SPAN
-></A
->
- (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
- <SPAN
-CLASS="emphasis"
-><I
-CLASS="EMPHASIS"
->off</I
-></SPAN
-> any <A
-HREF="actions-file.html#FAST-REDIRECTS"
-><SPAN
-CLASS="QUOTE"
->"+fast-redirects"</SPAN
-></A
->
- action, allowing this to take place unmolested. Note that there is a leading
- dot here -- <SPAN
-CLASS="QUOTE"
->".google.com"</SPAN
->. This will match any hosts and
- sub-domains, in the google.com domain also, such as
- <SPAN
-CLASS="QUOTE"
->"www.google.com"</SPAN
-> or <SPAN
-CLASS="QUOTE"
->"mail.google.com"</SPAN
->. But it would not
- match <SPAN
-CLASS="QUOTE"
->"www.google.de"</SPAN
->! So, apparently, we have these two actions
- defined as exceptions to the general rules at the top somewhere in the lower
- part of our <TT
-CLASS="FILENAME"
->default.action</TT
-> file, and
- <SPAN
-CLASS="QUOTE"
->"google.com"</SPAN
-> is referenced somewhere in these latter sections.</P
-><P
-> Then, for our <TT
-CLASS="FILENAME"
->user.action</TT
-> 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 <TT
-CLASS="FILENAME"
->default.action</TT
->.
- <TT
-CLASS="FILENAME"
->user.action</TT
-> typically has the last word. This is the
- best place to put hard and fast exceptions,</P
-><P
-> And finally we pull it all together in the bottom section and summarize how
- <SPAN
-CLASS="APPLICATION"
->Privoxy</SPAN
-> is applying all its <SPAN
-CLASS="QUOTE"
->"actions"</SPAN
->
- to <SPAN
-CLASS="QUOTE"
->"google.com"</SPAN
->: </P
-><P
-> <TABLE
-BORDER="0"
-BGCOLOR="#E0E0E0"
-WIDTH="100%"
-><TR
-><TD
-><PRE
-CLASS="SCREEN"
-> Final results:
-
+In file: user.action <span class="GUIBUTTON">[ View ]</span> <span class=
+"GUIBUTTON">[ Edit ]</span>
+(no matches in this file)
+</pre>
+ </td>
+ </tr>
+ </table>
+
+ <p>This is telling us how we have defined our <a href=
+ "actions-file.html#ACTIONS"><span class="QUOTE">"actions"</span></a>,
+ and which ones match for our test case, <span class=
+ "QUOTE">"google.com"</span>. Displayed is all the actions that are
+ available to us. Remember, the <tt class="LITERAL">+</tt> sign denotes
+ <span class="QUOTE">"on"</span>. <tt class="LITERAL">-</tt> denotes
+ <span class="QUOTE">"off"</span>. So some are <span class=
+ "QUOTE">"on"</span> here, but many are <span class=
+ "QUOTE">"off"</span>. Each example we try may provide a slightly
+ different end result, depending on our configuration directives.</p>
+
+ <p>The first listing is for our <tt class=
+ "FILENAME">default.action</tt> 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 <span class="QUOTE">"actions"</span>
+ file, this would be the section just below the <span class=
+ "QUOTE">"aliases"</span> section near the top. This will apply to all
+ URLs as signified by the single forward slash at the end of the listing
+ -- <span class="QUOTE">" / "</span>.</p>
+
+ <p>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 <span class="QUOTE">".google.com"</span>.
+ The first is negating our previous cookie setting, which was for
+ <a href="actions-file.html#SESSION-COOKIES-ONLY"><span class=
+ "QUOTE">"+session-cookies-only"</span></a> (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 <span class="emphasis"><i class=
+ "EMPHASIS">off</i></span> any <a href=
+ "actions-file.html#FAST-REDIRECTS"><span class=
+ "QUOTE">"+fast-redirects"</span></a> action, allowing this to take
+ place unmolested. Note that there is a leading dot here -- <span class=
+ "QUOTE">".google.com"</span>. This will match any hosts and
+ sub-domains, in the google.com domain also, such as <span class=
+ "QUOTE">"www.google.com"</span> or <span class=
+ "QUOTE">"mail.google.com"</span>. But it would not match <span class=
+ "QUOTE">"www.google.de"</span>! So, apparently, we have these two
+ actions defined as exceptions to the general rules at the top somewhere
+ in the lower part of our <tt class="FILENAME">default.action</tt> file,
+ and <span class="QUOTE">"google.com"</span> is referenced somewhere in
+ these latter sections.</p>
+
+ <p>Then, for our <tt class="FILENAME">user.action</tt> 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
+ <tt class="FILENAME">default.action</tt>. <tt class=
+ "FILENAME">user.action</tt> typically has the last word. This is the
+ best place to put hard and fast exceptions,</p>
+
+ <p>And finally we pull it all together in the bottom section and
+ summarize how <span class="APPLICATION">Privoxy</span> is applying all
+ its <span class="QUOTE">"actions"</span> to <span class=
+ "QUOTE">"google.com"</span>:</p>
+
+ <table border="0" bgcolor="#E0E0E0" width="100%">
+ <tr>
+ <td>
+ <pre class="SCREEN">
+ Final results:
+
-add-header
-block
- +change-x-forwarded-for{block}
+ +change-x-forwarded-for{block}
-client-header-filter{hide-tor-exit-notation}
-content-type-overwrite
-crunch-client-header
-prevent-compression
-redirect
-server-header-filter{xml-to-html}
- -server-header-filter{html-to-xml}
+ -server-header-filter{html-to-xml}
-session-cookies-only
- +set-image-blocker {pattern} </PRE
-></TD
-></TR
-></TABLE
-></P
-><P
-> Notice the only difference here to the previous listing, is to
- <SPAN
-CLASS="QUOTE"
->"fast-redirects"</SPAN
-> and <SPAN
-CLASS="QUOTE"
->"session-cookies-only"</SPAN
->,
- which are activated specifically for this site in our configuration,
- and thus show in the <SPAN
-CLASS="QUOTE"
->"Final Results"</SPAN
->.</P
-><P
-> Now another example, <SPAN
-CLASS="QUOTE"
->"ad.doubleclick.net"</SPAN
->:</P
-><P
-> <TABLE
-BORDER="0"
-BGCOLOR="#E0E0E0"
-WIDTH="100%"
-><TR
-><TD
-><PRE
-CLASS="SCREEN"
-> { +block{Domains starts with "ad"} }
+ +set-image-blocker {pattern}
+</pre>
+ </td>
+ </tr>
+ </table>
+
+ <p>Notice the only difference here to the previous listing, is to
+ <span class="QUOTE">"fast-redirects"</span> and <span class=
+ "QUOTE">"session-cookies-only"</span>, which are activated specifically
+ for this site in our configuration, and thus show in the <span class=
+ "QUOTE">"Final Results"</span>.</p>
+
+ <p>Now another example, <span class=
+ "QUOTE">"ad.doubleclick.net"</span>:</p>
+
+ <table border="0" bgcolor="#E0E0E0" width="100%">
+ <tr>
+ <td>
+ <pre class="SCREEN">
+ { +block{Domains starts with "ad"} }
ad*.
{ +block{Domain contains "ad"} }
.ad.
{ +block{Doubleclick banner server} +handle-as-image }
- .[a-vx-z]*.doubleclick.net</PRE
-></TD
-></TR
-></TABLE
-></P
-><P
-> We'll just show the interesting part here - the explicit matches. It is
- matched three different times. Two <SPAN
-CLASS="QUOTE"
->"+block{}"</SPAN
-> sections,
- and a <SPAN
-CLASS="QUOTE"
->"+block{} +handle-as-image"</SPAN
->,
- which is the expanded form of one of our aliases that had been defined as:
- <SPAN
-CLASS="QUOTE"
->"+block-as-image"</SPAN
->. (<A
-HREF="actions-file.html#ALIASES"
-><SPAN
-CLASS="QUOTE"
->"Aliases"</SPAN
-></A
-> are defined in
- the first section of the actions file and typically used to combine more
- than one action.)</P
-><P
-> 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 <SPAN
-CLASS="QUOTE"
->"ad.doubleclick.net"</SPAN
->
- is done here -- as both a <A
-HREF="actions-file.html#BLOCK"
-><SPAN
-CLASS="QUOTE"
->"+block{}"</SPAN
-></A
->
- <SPAN
-CLASS="emphasis"
-><I
-CLASS="EMPHASIS"
->and</I
-></SPAN
-> an
- <A
-HREF="actions-file.html#HANDLE-AS-IMAGE"
-><SPAN
-CLASS="QUOTE"
->"+handle-as-image"</SPAN
-></A
->.
- The custom alias <SPAN
-CLASS="QUOTE"
->"<TT
-CLASS="LITERAL"
->+block-as-image</TT
->"</SPAN
-> just
- simplifies the process and make it more readable.</P
-><P
-> One last example. Let's try <SPAN
-CLASS="QUOTE"
->"http://www.example.net/adsl/HOWTO/"</SPAN
->.
- This one is giving us problems. We are getting a blank page. Hmmm ...</P
-><P
-> <TABLE
-BORDER="0"
-BGCOLOR="#E0E0E0"
-WIDTH="100%"
-><TR
-><TD
-><PRE
-CLASS="SCREEN"
-> Matches for http://www.example.net/adsl/HOWTO/:
-
- In file: default.action <SPAN
-CLASS="GUIBUTTON"
->[ View ]</SPAN
-> <SPAN
-CLASS="GUIBUTTON"
->[ Edit ]</SPAN
->
-
- {-add-header
+ .[a-vx-z]*.doubleclick.net
+</pre>
+ </td>
+ </tr>
+ </table>
+
+ <p>We'll just show the interesting part here - the explicit matches. It
+ is matched three different times. Two <span class=
+ "QUOTE">"+block{}"</span> sections, and a <span class="QUOTE">"+block{}
+ +handle-as-image"</span>, which is the expanded form of one of our
+ aliases that had been defined as: <span class=
+ "QUOTE">"+block-as-image"</span>. (<a href=
+ "actions-file.html#ALIASES"><span class="QUOTE">"Aliases"</span></a>
+ are defined in the first section of the actions file and typically used
+ to combine more than one action.)</p>
+
+ <p>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 <span class=
+ "QUOTE">"ad.doubleclick.net"</span> is done here -- as both a <a href=
+ "actions-file.html#BLOCK"><span class="QUOTE">"+block{}"</span></a>
+ <span class="emphasis"><i class="EMPHASIS">and</i></span> an <a href=
+ "actions-file.html#HANDLE-AS-IMAGE"><span class=
+ "QUOTE">"+handle-as-image"</span></a>. The custom alias <span class=
+ "QUOTE">"<tt class="LITERAL">+block-as-image</tt>"</span> just
+ simplifies the process and make it more readable.</p>
+
+ <p>One last example. Let's try <span class=
+ "QUOTE">"http://www.example.net/adsl/HOWTO/"</span>. This one is giving
+ us problems. We are getting a blank page. Hmmm ...</p>
+
+ <table border="0" bgcolor="#E0E0E0" width="100%">
+ <tr>
+ <td>
+ <pre class="SCREEN">
+ Matches for http://www.example.net/adsl/HOWTO/:
+
+ In file: default.action <span class="GUIBUTTON">[ View ]</span> <span class=
+"GUIBUTTON">[ Edit ]</span>
+
+ {-add-header
-block
- +change-x-forwarded-for{block}
+ +change-x-forwarded-for{block}
-client-header-filter{hide-tor-exit-notation}
-content-type-overwrite
-crunch-client-header
-crunch-incoming-cookies
-crunch-outgoing-cookies
-crunch-server-header
- +deanimate-gifs
- -downgrade-http-version
+ +deanimate-gifs
+ -downgrade-http-version
+fast-redirects {check-decoded-url}
-filter {js-events}
-filter {content-cookies}
-filter {no-ping}
-force-text-mode
-handle-as-empty-document
- -handle-as-image
+ -handle-as-image
-hide-accept-language
- -hide-content-disposition
- +hide-from-header{block}
- +hide-referer{forge}
- -hide-user-agent
+ -hide-content-disposition
+ +hide-from-header{block}
+ +hide-referer{forge}
+ -hide-user-agent
-overwrite-last-modified
- +prevent-compression
+ +prevent-compression
-redirect
-server-header-filter{xml-to-html}
- -server-header-filter{html-to-xml}
- +session-cookies-only
+ -server-header-filter{html-to-xml}
+ +session-cookies-only
+set-image-blocker{blank} }
/
{ +block{Path contains "ads".} +handle-as-image }
- /ads</PRE
-></TD
-></TR
-></TABLE
-></P
-><P
-> Ooops, the <SPAN
-CLASS="QUOTE"
->"/adsl/"</SPAN
-> is matching <SPAN
-CLASS="QUOTE"
->"/ads"</SPAN
-> 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 <SPAN
-CLASS="APPLICATION"
->Privoxy</SPAN
-> 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
- <TT
-CLASS="FILENAME"
->user.action</TT
-> file) that explicitly
- <SPAN
-CLASS="emphasis"
-><I
-CLASS="EMPHASIS"
->un</I
-></SPAN
-> blocks (
- <A
-HREF="actions-file.html#BLOCK"
-><SPAN
-CLASS="QUOTE"
->"{-block}"</SPAN
-></A
->) paths with
- <SPAN
-CLASS="QUOTE"
->"adsl"</SPAN
-> in them (remember, last match in the configuration
- wins). There are various ways to handle such exceptions. Example:</P
-><P
-> <TABLE
-BORDER="0"
-BGCOLOR="#E0E0E0"
-WIDTH="100%"
-><TR
-><TD
-><PRE
-CLASS="SCREEN"
-> { -block }
- /adsl</PRE
-></TD
-></TR
-></TABLE
-></P
-><P
-> 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 <TT
-CLASS="LITERAL"
->Shift+Reload</TT
->.</P
-><P
-> But now what about a situation where we get no explicit matches like
- we did with:</P
-><P
-> <TABLE
-BORDER="0"
-BGCOLOR="#E0E0E0"
-WIDTH="100%"
-><TR
-><TD
-><PRE
-CLASS="SCREEN"
-> { +block{Path starts with "ads".} +handle-as-image }
- /ads</PRE
-></TD
-></TR
-></TABLE
-></P
-><P
-> 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 <TT
-CLASS="FILENAME"
->default.action</TT
-> 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
- <A
-HREF="actions-file.html#FILTER"
-><SPAN
-CLASS="QUOTE"
->"+filter"</SPAN
-></A
-> actions.
- These tend to be harder to troubleshoot.
- Try adding the URL for the site to one of aliases that turn off
- <A
-HREF="actions-file.html#FILTER"
-><SPAN
-CLASS="QUOTE"
->"+filter"</SPAN
-></A
->:</P
-><P
-> <TABLE
-BORDER="0"
-BGCOLOR="#E0E0E0"
-WIDTH="100%"
-><TR
-><TD
-><PRE
-CLASS="SCREEN"
-> { shop }
+ /ads
+</pre>
+ </td>
+ </tr>
+ </table>
+
+ <p>Ooops, the <span class="QUOTE">"/adsl/"</span> is matching
+ <span class="QUOTE">"/ads"</span> 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 <span class=
+ "APPLICATION">Privoxy</span> 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 <tt class=
+ "FILENAME">user.action</tt> file) that explicitly <span class=
+ "emphasis"><i class="EMPHASIS">un</i></span> blocks ( <a href=
+ "actions-file.html#BLOCK"><span class="QUOTE">"{-block}"</span></a>)
+ paths with <span class="QUOTE">"adsl"</span> in them (remember, last
+ match in the configuration wins). There are various ways to handle such
+ exceptions. Example:</p>
+
+ <table border="0" bgcolor="#E0E0E0" width="100%">
+ <tr>
+ <td>
+ <pre class="SCREEN">
+ { -block }
+ /adsl
+</pre>
+ </td>
+ </tr>
+ </table>
+
+ <p>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 <tt class=
+ "LITERAL">Shift+Reload</tt>.</p>
+
+ <p>But now what about a situation where we get no explicit matches like
+ we did with:</p>
+
+ <table border="0" bgcolor="#E0E0E0" width="100%">
+ <tr>
+ <td>
+ <pre class="SCREEN">
+ { +block{Path starts with "ads".} +handle-as-image }
+ /ads
+</pre>
+ </td>
+ </tr>
+ </table>
+
+ <p>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 <tt class=
+ "FILENAME">default.action</tt> 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 <a href=
+ "actions-file.html#FILTER"><span class="QUOTE">"+filter"</span></a>
+ actions. These tend to be harder to troubleshoot. Try adding the URL
+ for the site to one of aliases that turn off <a href=
+ "actions-file.html#FILTER"><span class=
+ "QUOTE">"+filter"</span></a>:</p>
+
+ <table border="0" bgcolor="#E0E0E0" width="100%">
+ <tr>
+ <td>
+ <pre class="SCREEN">
+ { shop }
.quietpc.com
.worldpay.com # for quietpc.com
.jungle.com
.scan.co.uk
- .forbes.com</PRE
-></TD
-></TR
-></TABLE
-></P
-><P
-> <SPAN
-CLASS="QUOTE"
->"<TT
-CLASS="LITERAL"
->{ shop }</TT
->"</SPAN
-> is an <SPAN
-CLASS="QUOTE"
->"alias"</SPAN
-> that expands to
- <SPAN
-CLASS="QUOTE"
->"<TT
-CLASS="LITERAL"
->{ -filter -session-cookies-only }</TT
->"</SPAN
->.
- Or you could do your own exception to negate filtering: </P
-><P
-> <TABLE
-BORDER="0"
-BGCOLOR="#E0E0E0"
-WIDTH="100%"
-><TR
-><TD
-><PRE
-CLASS="SCREEN"
-> { -filter }
+ .forbes.com
+</pre>
+ </td>
+ </tr>
+ </table>
+
+ <p><span class="QUOTE">"<tt class="LITERAL">{ shop }</tt>"</span> is an
+ <span class="QUOTE">"alias"</span> that expands to <span class=
+ "QUOTE">"<tt class="LITERAL">{ -filter -session-cookies-only
+ }</tt>"</span>. Or you could do your own exception to negate
+ filtering:</p>
+
+ <table border="0" bgcolor="#E0E0E0" width="100%">
+ <tr>
+ <td>
+ <pre class="SCREEN">
+ { -filter }
# Disable ALL filter actions for sites in this section
.forbes.com
developer.ibm.com
- localhost</PRE
-></TD
-></TR
-></TABLE
-></P
-><P
-> This would turn off all filtering for these sites. This is best
- put in <TT
-CLASS="FILENAME"
->user.action</TT
->, 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
- automatically in the scope of the action.</P
-><P
-> Images that are inexplicably being blocked, may well be hitting the
-<A
-HREF="actions-file.html#FILTER-BANNERS-BY-SIZE"
-><SPAN
-CLASS="QUOTE"
->"+filter{banners-by-size}"</SPAN
-></A
->
- rule, which assumes
- that images of certain sizes are ad banners (works well
- <SPAN
-CLASS="emphasis"
-><I
-CLASS="EMPHASIS"
->most of the time</I
-></SPAN
-> since these tend to be standardized).</P
-><P
-> <SPAN
-CLASS="QUOTE"
->"<TT
-CLASS="LITERAL"
->{ fragile }</TT
->"</SPAN
-> 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. </P
-><P
-> <TABLE
-BORDER="0"
-BGCOLOR="#E0E0E0"
-WIDTH="100%"
-><TR
-><TD
-><PRE
-CLASS="SCREEN"
-> { fragile }
+ localhost
+</pre>
+ </td>
+ </tr>
+ </table>
+
+ <p>This would turn off all filtering for these sites. This is best put
+ in <tt class="FILENAME">user.action</tt>, 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
+ automatically in the scope of the action.</p>
+
+ <p>Images that are inexplicably being blocked, may well be hitting the
+ <a href="actions-file.html#FILTER-BANNERS-BY-SIZE"><span class=
+ "QUOTE">"+filter{banners-by-size}"</span></a> rule, which assumes that
+ images of certain sizes are ad banners (works well <span class=
+ "emphasis"><i class="EMPHASIS">most of the time</i></span> since these
+ tend to be standardized).</p>
+
+ <p><span class="QUOTE">"<tt class="LITERAL">{ fragile }</tt>"</span> 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.</p>
+
+ <table border="0" bgcolor="#E0E0E0" width="100%">
+ <tr>
+ <td>
+ <pre class="SCREEN">
+ { fragile }
# Handle with care: easy to break
mail.google.
- mybank.example.com</PRE
-></TD
-></TR
-></TABLE
-></P
-><P
-> <SPAN
-CLASS="emphasis"
-><I
-CLASS="EMPHASIS"
->Remember to flush caches!</I
-></SPAN
-> Note that the
- <TT
-CLASS="LITERAL"
->mail.google</TT
-> reference lacks the TLD portion (e.g.
- <SPAN
-CLASS="QUOTE"
->".com"</SPAN
->). This will effectively match any TLD with
- <TT
-CLASS="LITERAL"
->google</TT
-> in it, such as <TT
-CLASS="LITERAL"
->mail.google.de.</TT
->,
- just as an example.</P
-><P
->
- 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.</P
-></DIV
-></DIV
-><DIV
-CLASS="NAVFOOTER"
-><HR
-ALIGN="LEFT"
-WIDTH="100%"><TABLE
-SUMMARY="Footer navigation table"
-WIDTH="100%"
-BORDER="0"
-CELLPADDING="0"
-CELLSPACING="0"
-><TR
-><TD
-WIDTH="33%"
-ALIGN="left"
-VALIGN="top"
-><A
-HREF="seealso.html"
-ACCESSKEY="P"
->Prev</A
-></TD
-><TD
-WIDTH="34%"
-ALIGN="center"
-VALIGN="top"
-><A
-HREF="index.html"
-ACCESSKEY="H"
->Home</A
-></TD
-><TD
-WIDTH="33%"
-ALIGN="right"
-VALIGN="top"
-> </TD
-></TR
-><TR
-><TD
-WIDTH="33%"
-ALIGN="left"
-VALIGN="top"
->See Also</TD
-><TD
-WIDTH="34%"
-ALIGN="center"
-VALIGN="top"
-> </TD
-><TD
-WIDTH="33%"
-ALIGN="right"
-VALIGN="top"
-> </TD
-></TR
-></TABLE
-></DIV
-></BODY
-></HTML
->
+ mybank.example.com
+</pre>
+ </td>
+ </tr>
+ </table>
+
+ <p><span class="emphasis"><i class="EMPHASIS">Remember to flush
+ caches!</i></span> Note that the <tt class="LITERAL">mail.google</tt>
+ reference lacks the TLD portion (e.g. <span class=
+ "QUOTE">".com"</span>). This will effectively match any TLD with
+ <tt class="LITERAL">google</tt> in it, such as <tt class=
+ "LITERAL">mail.google.de.</tt>, just as an example.</p>
+
+ <p>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.</p>
+ </div>
+ </div>
+
+ <div class="NAVFOOTER">
+ <hr align="left" width="100%">
+
+ <table summary="Footer navigation table" width="100%" border="0"
+ cellpadding="0" cellspacing="0">
+ <tr>
+ <td width="33%" align="left" valign="top"><a href="seealso.html"
+ accesskey="P">Prev</a></td>
+
+ <td width="34%" align="center" valign="top"><a href="index.html"
+ accesskey="H">Home</a></td>
+
+ <td width="33%" align="right" valign="top"> </td>
+ </tr>
+
+ <tr>
+ <td width="33%" align="left" valign="top">See Also</td>
+
+ <td width="34%" align="center" valign="top"> </td>
+
+ <td width="33%" align="right" valign="top"> </td>
+ </tr>
+ </table>
+ </div>
+</body>
+</html>
projects / privoxy.git / blobdiff