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42 >Privoxy 3.0.9 User Manual</TH
83 >14.1. Regular Expressions</A
89 > uses Perl-style <SPAN
94 HREF="actions-file.html"
98 HREF="filter-file.html"
102 HREF="http://www.pcre.org/"
111 > If you are reading this, you probably don't understand what <SPAN
115 > are, or what they can do. So this will be a very brief
116 introduction only. A full explanation would require a <A
117 HREF="http://www.oreilly.com/catalog/regex/"
122 > Regular expressions provide a language to describe patterns that can be
123 run against strings of characters (letter, numbers, etc), to see if they
124 match the string or not. The patterns are themselves (sometimes complex)
125 strings of literal characters, combined with wild-cards, and other special
126 characters, called meta-characters. The <SPAN
128 >"meta-characters"</SPAN
130 special meanings and are used to build complex patterns to be matched against.
131 Perl Compatible Regular Expressions are an especially convenient
135 > of the regular expression language.</P
137 > To make a simple analogy, we do something similar when we use wild-card
138 characters when listing files with the <B
145 > matches all filenames. The <SPAN
149 character here is the asterisk which matches any and all characters. We can be
150 more specific and use <TT
153 > to match just individual
156 >"dir file?.text"</SPAN
164 >, etc. We are pattern
165 matching, using a similar technique to <SPAN
167 >"regular expressions"</SPAN
170 > Regular expressions do essentially the same thing, but are much, much more
171 powerful. There are many more <SPAN
173 >"special characters"</SPAN
175 building complex patterns however. Let's look at a few of the common ones,
176 and then some examples:</P
191 > - Matches any single character, e.g. <SPAN
229 > - The preceding character or expression is matched ZERO or ONE
252 > - The preceding character or expression is matched ONE or MORE
275 > - The preceding character or expression is matched ZERO or MORE
301 > character denotes that
302 the following character should be taken literally. This is used where one of the
303 special characters (e.g. <SPAN
306 >) needs to be taken literally and
307 not as a special meta-character. Example: <SPAN
309 >"example\.com"</SPAN
311 sure the period is recognized only as a period (and not expanded to its
312 meta-character meaning of any single character).
334 > - Characters enclosed in brackets will be matched if
335 any of the enclosed characters are encountered. For instance, <SPAN
339 matches any numeric digit (zero through nine). As an example, we can combine
343 > to match any digit one of more times: <SPAN
368 > - parentheses are used to group a sub-expression,
369 or multiple sub-expressions.
394 > character works like an
398 > conditional statement. A match is successful if the
399 sub-expression on either side of <SPAN
402 > matches. As an example:
405 >"/(this|that) example/"</SPAN
406 > uses grouping and the bar character
407 and would match either <SPAN
409 >"this example"</SPAN
423 > These are just some of the ones you are likely to use when matching URLs with
427 >, and is a long way from a definitive
428 list. This is enough to get us started with a few simple examples which may
429 be more illuminating:</P
441 that uses the common combination of <SPAN
448 denote any character, zero or more times. In other words, any string at all.
449 So we start with a literal forward slash, then our regular expression pattern
453 >) another literal forward slash, the string
457 >, another forward slash, and lastly another
462 a directory path here. This will match any file with the path that has a
463 directory named <SPAN
470 any characters, and this could conceivably be more forward slashes, so it
471 might expand into a much longer looking path. For example, this could match:
474 >"/eye/hate/spammers/banners/annoy_me_please.gif"</SPAN
478 >"/banners/annoying.html"</SPAN
479 >, or almost an infinite number of other
480 possible combinations, just so it has <SPAN
486 > And now something a little more complex:</P
494 >/.*/adv((er)?ts?|ertis(ing|ements?))?/</TT
498 We have several literal forward slashes again (<SPAN
502 building another expression that is a file path statement. We have another
506 >, so we are matching against any conceivable sub-path, just so
507 it matches our expression. The only true literal that <SPAN
514 > our pattern is <SPAN
518 the forward slashes. What comes after the <SPAN
522 interesting part. </P
527 > means the preceding expression (either a
528 literal character or anything grouped with <SPAN
532 can exist or not, since this means either zero or one match. So
535 >"((er)?ts?|ertis(ing|ements?))"</SPAN
536 > is optional, as are the
537 individual sub-expressions: <SPAN
543 >"(ing|ements?)"</SPAN
554 >. We have two of those. For instance,
557 >"(ing|ements?)"</SPAN
558 >, can expand to match either <SPAN
571 >. What is being done here, is an
572 attempt at matching as many variations of <SPAN
574 >"advertisement"</SPAN
576 similar, as possible. So this would expand to match just <SPAN
592 >"advertisement"</SPAN
596 >"advertisements"</SPAN
597 >. You get the idea. But it would not match
600 >"advertizements"</SPAN
604 >). We could fix that by
605 changing our regular expression to:
608 >"/.*/adv((er)?ts?|erti(s|z)(ing|ements?))?/"</SPAN
609 >, which would then match
618 >/.*/advert[0-9]+\.(gif|jpe?g)</TT
622 another path statement with forward slashes. Anything in the square brackets
626 > can be matched. This is using <SPAN
630 shorthand expression to mean any digit one through nine. It is the same as
634 >. So any digit matches. The <SPAN
638 means one or more of the preceding expression must be included. The preceding
639 expression here is what is in the square brackets -- in this case, any digit
640 one through nine. Then, at the end, we have a grouping: <SPAN
644 This includes a <SPAN
647 >, so this needs to match the expression on
648 either side of that bar character also. A simple <SPAN
651 > on one side, and the other
652 side will in turn match either <SPAN
662 > means the letter <SPAN
666 can be matched once or not at all. So we are building an expression here to
667 match image GIF or JPEG type image file. It must include the literal
671 >, then one or more digits, and a <SPAN
675 (which is now a literal, and not a special character, since it is escaped
679 >), and lastly either <SPAN
689 >. Some possible matches would
692 >"//advert1.jpg"</SPAN
696 >"/nasty/ads/advert1234.gif"</SPAN
700 >"/banners/from/hell/advert99.jpg"</SPAN
701 >. It would not match
705 > (no leading slash), or
708 >"/adverts232.jpg"</SPAN
709 > (the expression does not include an
715 >"/advert1.jsp"</SPAN
720 in the expression anywhere).</P
722 > We are barely scratching the surface of regular expressions here so that you
723 can understand the default <SPAN
727 configuration files, and maybe use this knowledge to customize your own
728 installation. There is much, much more that can be done with regular
729 expressions. Now that you know enough to get started, you can learn more on
732 > More reading on Perl Compatible Regular expressions:
734 HREF="http://perldoc.perl.org/perlre.html"
736 >http://perldoc.perl.org/perlre.html</A
739 > For information on regular expression based substitutions and their applications
740 in filters, please see the <A
741 HREF="filter-file.html"
742 >filter file tutorial</A
752 >14.2. Privoxy's Internal Pages</A
758 > proxies each requested
759 web page, it is easy for <SPAN
763 trap certain special URLs. In this way, we can talk directly to
768 configured, see how our rules are being applied, change these
769 rules and other configuration options, and even turn
773 > filtering off, all with
774 a web browser. </P
776 > The URLs listed below are the special ones that allow direct access
784 > must be running to access these. If
785 not, you will get a friendly error message. Internet access is not
804 HREF="http://config.privoxy.org/"
806 >http://config.privoxy.org/</A
811 > There is a shortcut: <A
816 doesn't provide a fall-back to a real page, in case the request is not
826 Show information about the current configuration, including viewing and
827 editing of actions files:
837 HREF="http://config.privoxy.org/show-status"
839 >http://config.privoxy.org/show-status</A
847 Show the source code version numbers:
857 HREF="http://config.privoxy.org/show-version"
859 >http://config.privoxy.org/show-version</A
867 Show the browser's request headers:
877 HREF="http://config.privoxy.org/show-request"
879 >http://config.privoxy.org/show-request</A
887 Show which actions apply to a URL and why:
897 HREF="http://config.privoxy.org/show-url-info"
899 >http://config.privoxy.org/show-url-info</A
907 Toggle Privoxy on or off. This feature can be turned off/on in the main
911 > file. When toggled <SPAN
918 continues to run, but only as a pass-through proxy, with no actions taking
929 HREF="http://config.privoxy.org/toggle"
931 >http://config.privoxy.org/toggle</A
936 > Short cuts. Turn off, then on:
946 HREF="http://config.privoxy.org/toggle?set=disable"
948 >http://config.privoxy.org/toggle?set=disable</A
960 HREF="http://config.privoxy.org/toggle?set=enable"
962 >http://config.privoxy.org/toggle?set=enable</A
970 > These may be bookmarked for quick reference. See next. </P
977 >14.2.1. Bookmarklets</A
980 > Below are some <SPAN
982 >"bookmarklets"</SPAN
983 > to allow you to easily access a
987 > version of some of <SPAN
991 special pages. They are designed for MS Internet Explorer, but should work
992 equally well in Netscape, Mozilla, and other browsers which support
993 JavaScript. They are designed to run directly from your bookmarks - not by
994 clicking the links below (although that should work for testing).</P
996 > To save them, right-click the link and choose <SPAN
998 >"Add to Favorites"</SPAN
1002 >"Add Bookmark"</SPAN
1003 > (Netscape). You will get a warning that
1006 >"may not be safe"</SPAN
1007 > - just click OK. Then you can run the
1008 Bookmarklet directly from your favorites/bookmarks. For even faster access,
1009 you can put them on the <SPAN
1012 > bar (IE) or the <SPAN
1016 > (Netscape), and run them with a single click. </P
1024 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());"
1026 >Privoxy - Enable</A
1033 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());"
1035 >Privoxy - Disable</A
1042 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());"
1044 >Privoxy - Toggle Privoxy</A
1045 > (Toggles between enabled and disabled)
1051 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());"
1053 >Privoxy- View Status</A
1060 HREF="javascript:void(window.open('http://config.privoxy.org/show-url-info?url='+escape(location.href),'Why').focus());"
1069 > Credit: The site which gave us the general idea for these bookmarklets is
1071 HREF="http://www.bookmarklets.com/"
1073 >www.bookmarklets.com</A
1075 have more information about bookmarklets. </P
1084 >14.3. Chain of Events</A
1087 > Let's take a quick look at how some of <SPAN
1091 core features are triggered, and the ensuing sequence of events when a web
1092 page is requested by your browser:</P
1099 > First, your web browser requests a web page. The browser knows to send
1100 the request to <SPAN
1103 >, which will in turn,
1104 relay the request to the remote web server after passing the following
1113 > traps any request for its own internal CGI
1118 >) and sends the CGI page back to the browser.
1126 > checks to see if the URL
1128 HREF="actions-file.html#BLOCK"
1134 so, the URL is then blocked, and the remote web server will not be contacted.
1136 HREF="actions-file.html#HANDLE-AS-IMAGE"
1139 >"+handle-as-image"</SPAN
1144 HREF="actions-file.html#HANDLE-AS-EMPTY-DOCUMENT"
1147 >"+handle-as-empty-document"</SPAN
1150 are then checked, and if there is no match, an
1154 > page is sent back to the browser. Otherwise, if
1155 it does match, an image is returned for the former, and an empty text
1156 document for the latter. The type of image would depend on the setting of
1158 HREF="actions-file.html#SET-IMAGE-BLOCKER"
1161 >"+set-image-blocker"</SPAN
1164 (blank, checkerboard pattern, or an HTTP redirect to an image elsewhere).
1169 > Untrusted URLs are blocked. If URLs are being added to the
1173 > file, then that is done.
1178 > If the URL pattern matches the <A
1179 HREF="actions-file.html#FAST-REDIRECTS"
1182 >"+fast-redirects"</SPAN
1185 it is then processed. Unwanted parts of the requested URL are stripped.
1190 > Now the rest of the client browser's request headers are processed. If any
1191 of these match any of the relevant actions (e.g. <A
1192 HREF="actions-file.html#HIDE-USER-AGENT"
1195 >"+hide-user-agent"</SPAN
1198 etc.), headers are suppressed or forged as determined by these actions and
1204 > Now the web server starts sending its response back (i.e. typically a web
1210 > First, the server headers are read and processed to determine, among other
1211 things, the MIME type (document type) and encoding. The headers are then
1212 filtered as determined by the
1214 HREF="actions-file.html#CRUNCH-INCOMING-COOKIES"
1217 >"+crunch-incoming-cookies"</SPAN
1221 HREF="actions-file.html#SESSION-COOKIES-ONLY"
1224 >"+session-cookies-only"</SPAN
1228 HREF="actions-file.html#DOWNGRADE-HTTP-VERSION"
1231 >"+downgrade-http-version"</SPAN
1240 HREF="actions-file.html#KILL-POPUPS"
1243 >"+kill-popups"</SPAN
1246 action applies, and it is an HTML or JavaScript document, the popup-code in the
1247 response is filtered on-the-fly as it is received.
1253 HREF="actions-file.html#FILTER"
1260 HREF="actions-file.html#DEANIMATE-GIFS"
1263 >"+deanimate-gifs"</SPAN
1266 action applies (and the document type fits the action), the rest of the page is
1267 read into memory (up to a configurable limit). Then the filter rules (from
1271 > and any other filter files) are
1272 processed against the buffered content. Filters are applied in the order
1273 they are specified in one of the filter files. Animated GIFs, if present,
1274 are reduced to either the first or last frame, depending on the action
1275 setting.The entire page, which is now filtered, is then sent by
1279 > back to your browser.
1283 HREF="actions-file.html#FILTER"
1290 HREF="actions-file.html#DEANIMATE-GIFS"
1293 >"+deanimate-gifs"</SPAN
1299 > passes the raw data through
1300 to the client browser as it becomes available.
1305 > As the browser receives the now (possibly filtered) page content, it
1306 reads and then requests any URLs that may be embedded within the page
1307 source, e.g. ad images, stylesheets, JavaScript, other HTML documents (e.g.
1308 frames), sounds, etc. For each of these objects, the browser issues a
1309 separate request (this is easily viewable in <SPAN
1313 logs). And each such request is in turn processed just as above. Note that a
1314 complex web page will have many, many such embedded URLs. If these
1315 secondary requests are to a different server, then quite possibly a very
1316 differing set of actions is triggered.
1322 > NOTE: This is somewhat of a simplistic overview of what happens with each URL
1323 request. For the sake of brevity and simplicity, we have focused on
1327 > core features only.</P
1335 >14.4. Troubleshooting: Anatomy of an Action</A
1343 HREF="actions-file.html#ACTIONS"
1346 HREF="actions-file.html#FILTER"
1349 to any given URL can be complex, and not always so
1350 easy to understand what is happening. And sometimes we need to be able to
1361 doing. Especially, if something <SPAN
1365 is causing us a problem inadvertently. It can be a little daunting to look at
1366 the actions and filters files themselves, since they tend to be filled with
1368 HREF="appendix.html#REGEX"
1369 >regular expressions</A
1370 > whose consequences are not
1371 always so obvious. </P
1373 > One quick test to see if <SPAN
1376 > is causing a problem
1377 or not, is to disable it temporarily. This should be the first troubleshooting
1379 HREF="appendix.html#BOOKMARKLETS"
1380 >the Bookmarklets</A
1381 > section on a quick
1382 and easy way to do this (be sure to flush caches afterward!). Looking at the
1383 logs is a good idea too. (Note that both the toggle feature and logging are
1387 > file settings, and may need to be
1393 > Another easy troubleshooting step to try is if you have done any
1394 customization of your installation, revert back to the installed
1395 defaults and see if that helps. There are times the developers get complaints
1396 about one thing or another, and the problem is more related to a customized
1397 configuration issue.</P
1404 HREF="http://config.privoxy.org/show-url-info"
1406 >http://config.privoxy.org/show-url-info</A
1408 page that can show us very specifically how <SPAN
1412 are being applied to any given URL. This is a big help for troubleshooting.</P
1414 > First, enter one URL (or partial URL) at the prompt, and then
1419 how the current configuration will handle it. This will not
1420 help with filtering effects (i.e. the <A
1421 HREF="actions-file.html#FILTER"
1427 one of the filter files since this is handled very
1428 differently and not so easy to trap! It also will not tell you about any other
1429 URLs that may be embedded within the URL you are testing. For instance, images
1430 such as ads are expressed as URLs within the raw page source of HTML pages. So
1431 you will only get info for the actual URL that is pasted into the prompt area
1432 -- not any sub-URLs. If you want to know about embedded URLs like ads, you
1433 will have to dig those out of the HTML source. Use your browser's <SPAN
1437 > option for this. Or right click on the ad, and grab the
1440 > Let's try an example, <A
1441 HREF="http://google.com"
1445 and look at it one section at a time in a sample configuration (your real
1446 configuration may vary):</P
1456 > Matches for http://www.google.com:
1458 In file: default.action <SPAN
1466 {+deanimate-gifs {last}
1467 +fast-redirects {check-decoded-url}
1468 +filter {refresh-tags}
1469 +filter {img-reorder}
1470 +filter {banners-by-size}
1472 +filter {jumping-windows}
1473 +filter {ie-exploits}
1474 +hide-forwarded-for-headers
1475 +hide-from-header {block}
1476 +hide-referrer {forge}
1477 +session-cookies-only
1478 +set-image-blocker {pattern}
1481 { -session-cookies-only }
1487 In file: user.action <SPAN
1494 (no matches in this file) </PRE
1500 > This is telling us how we have defined our
1502 HREF="actions-file.html#ACTIONS"
1508 which ones match for our test case, <SPAN
1512 Displayed is all the actions that are available to us. Remember,
1516 > sign denotes <SPAN
1526 >. So some are <SPAN
1533 >. Each example we try may provide a slightly different
1534 end result, depending on our configuration directives.</P
1540 > file. The large, multi-line
1541 listing, is how the actions are set to match for all URLs, i.e. our default
1542 settings. If you look at your <SPAN
1545 > file, this would be the
1546 section just below the <SPAN
1549 > section near the top. This
1550 will apply to all URLs as signified by the single forward slash at the end
1551 of the listing -- <SPAN
1556 > But we have defined additional actions that would be exceptions to these general
1557 rules, and then we list specific URLs (or patterns) that these exceptions
1558 would apply to. Last match wins. Just below this then are two explicit
1561 >".google.com"</SPAN
1562 >. The first is negating our previous
1563 cookie setting, which was for <A
1564 HREF="actions-file.html#SESSION-COOKIES-ONLY"
1567 >"+session-cookies-only"</SPAN
1570 (i.e. not persistent). So we will allow persistent cookies for google, at
1571 least that is how it is in this example. The second turns
1579 HREF="actions-file.html#FAST-REDIRECTS"
1582 >"+fast-redirects"</SPAN
1585 action, allowing this to take place unmolested. Note that there is a leading
1588 >".google.com"</SPAN
1589 >. This will match any hosts and
1590 sub-domains, in the google.com domain also, such as
1593 >"www.google.com"</SPAN
1596 >"mail.google.com"</SPAN
1600 >"www.google.de"</SPAN
1601 >! So, apparently, we have these two actions
1602 defined as exceptions to the general rules at the top somewhere in the lower
1610 > is referenced somewhere in these latter sections.</P
1615 > file, we again have no hits.
1616 So there is nothing google-specific that we might have added to our own, local
1617 configuration. If there was, those actions would over-rule any actions from
1618 previously processed files, such as <TT
1625 > typically has the last word. This is the
1626 best place to put hard and fast exceptions,</P
1628 > And finally we pull it all together in the bottom section and summarize how
1632 > is applying all its <SPAN
1649 > Final results:
1653 -client-header-filter{hide-tor-exit-notation}
1654 -content-type-overwrite
1655 -crunch-client-header
1656 -crunch-if-none-match
1657 -crunch-incoming-cookies
1658 -crunch-outgoing-cookies
1659 -crunch-server-header
1660 +deanimate-gifs {last}
1661 -downgrade-http-version
1664 -filter {content-cookies}
1665 -filter {all-popups}
1666 -filter {banners-by-link}
1667 -filter {tiny-textforms}
1668 -filter {frameset-borders}
1669 -filter {demoronizer}
1670 -filter {shockwave-flash}
1671 -filter {quicktime-kioskmode}
1673 -filter {crude-parental}
1674 -filter {site-specifics}
1675 -filter {js-annoyances}
1676 -filter {html-annoyances}
1677 +filter {refresh-tags}
1678 -filter {unsolicited-popups}
1679 +filter {img-reorder}
1680 +filter {banners-by-size}
1682 +filter {jumping-windows}
1683 +filter {ie-exploits}
1690 -handle-as-empty-document
1692 -hide-accept-language
1693 -hide-content-disposition
1694 +hide-forwarded-for-headers
1695 +hide-from-header {block}
1696 -hide-if-modified-since
1697 +hide-referrer {forge}
1702 -overwrite-last-modified
1703 -prevent-compression
1707 -server-header-filter{xml-to-html}
1708 -server-header-filter{html-to-xml}
1709 -session-cookies-only
1710 +set-image-blocker {pattern}
1711 -treat-forbidden-connects-like-blocks </PRE
1717 > Notice the only difference here to the previous listing, is to
1720 >"fast-redirects"</SPAN
1723 >"session-cookies-only"</SPAN
1725 which are activated specifically for this site in our configuration,
1726 and thus show in the <SPAN
1728 >"Final Results"</SPAN
1731 > Now another example, <SPAN
1733 >"ad.doubleclick.net"</SPAN
1750 { +block +handle-as-image }
1751 .[a-vx-z]*.doubleclick.net</PRE
1757 > We'll just show the interesting part here - the explicit matches. It is
1758 matched three different times. Two <SPAN
1764 >"+block +handle-as-image"</SPAN
1766 which is the expanded form of one of our aliases that had been defined as:
1769 >"+block-as-image"</SPAN
1771 HREF="actions-file.html#ALIASES"
1777 the first section of the actions file and typically used to combine more
1778 than one action.)</P
1780 > Any one of these would have done the trick and blocked this as an unwanted
1781 image. This is unnecessarily redundant since the last case effectively
1782 would also cover the first. No point in taking chances with these guys
1783 though ;-) Note that if you want an ad or obnoxious
1784 URL to be invisible, it should be defined as <SPAN
1786 >"ad.doubleclick.net"</SPAN
1788 is done here -- as both a <A
1789 HREF="actions-file.html#BLOCK"
1803 HREF="actions-file.html#HANDLE-AS-IMAGE"
1806 >"+handle-as-image"</SPAN
1809 The custom alias <SPAN
1813 >+block-as-image</TT
1816 simplifies the process and make it more readable.</P
1818 > One last example. Let's try <SPAN
1820 >"http://www.example.net/adsl/HOWTO/"</SPAN
1822 This one is giving us problems. We are getting a blank page. Hmmm ...</P
1832 > Matches for http://www.example.net/adsl/HOWTO/:
1834 In file: default.action <SPAN
1844 -client-header-filter{hide-tor-exit-notation}
1845 -content-type-overwrite
1846 -crunch-client-header
1847 -crunch-if-none-match
1848 -crunch-incoming-cookies
1849 -crunch-outgoing-cookies
1850 -crunch-server-header
1852 -downgrade-http-version
1853 +fast-redirects {check-decoded-url}
1855 -filter {content-cookies}
1856 -filter {all-popups}
1857 -filter {banners-by-link}
1858 -filter {tiny-textforms}
1859 -filter {frameset-borders}
1860 -filter {demoronizer}
1861 -filter {shockwave-flash}
1862 -filter {quicktime-kioskmode}
1864 -filter {crude-parental}
1865 -filter {site-specifics}
1866 -filter {js-annoyances}
1867 -filter {html-annoyances}
1868 +filter {refresh-tags}
1869 -filter {unsolicited-popups}
1870 +filter {img-reorder}
1871 +filter {banners-by-size}
1873 +filter {jumping-windows}
1874 +filter {ie-exploits}
1881 -handle-as-empty-document
1883 -hide-accept-language
1884 -hide-content-disposition
1885 +hide-forwarded-for-headers
1886 +hide-from-header{block}
1887 +hide-referer{forge}
1891 -overwrite-last-modified
1892 +prevent-compression
1896 -server-header-filter{xml-to-html}
1897 -server-header-filter{html-to-xml}
1898 +session-cookies-only
1899 +set-image-blocker{blank}
1900 -treat-forbidden-connects-like-blocks }
1903 { +block +handle-as-image }
1917 configuration! But we did not want this at all! Now we see why we get the
1918 blank page. It is actually triggering two different actions here, and
1919 the effects are aggregated so that the URL is blocked, and <SPAN
1923 to treat the block as if it were an image. But this is, of course, all wrong.
1924 We could now add a new action below this (or better in our own
1928 > file) that explicitly
1937 HREF="actions-file.html#BLOCK"
1946 > in them (remember, last match in the configuration
1947 wins). There are various ways to handle such exceptions. Example:</P
1964 > Now the page displays ;-)
1965 Remember to flush your browser's caches when making these kinds of changes to
1966 your configuration to insure that you get a freshly delivered page! Or, try
1972 > But now what about a situation where we get no explicit matches like
1983 > { +block +handle-as-image }
1990 > That actually was very helpful and pointed us quickly to where the problem
1991 was. If you don't get this kind of match, then it means one of the default
1992 rules in the first section of <TT
1996 the problem. This would require some guesswork, and maybe a little trial and
1997 error to isolate the offending rule. One likely cause would be one of the
1999 HREF="actions-file.html#FILTER"
2005 These tend to be harder to troubleshoot.
2006 Try adding the URL for the site to one of aliases that turn off
2008 HREF="actions-file.html#FILTER"
2025 .worldpay.com # for quietpc.com
2048 >{ -filter -session-cookies-only }</TT
2051 Or you could do your own exception to negate filtering: </P
2062 # Disable ALL filter actions for sites in this section
2071 > This would turn off all filtering for these sites. This is best
2076 exceptions. Note that when a simple domain pattern is used by itself (without
2077 the subsequent path portion), all sub-pages within that domain are included
2078 automatically in the scope of the action.</P
2080 > Images that are inexplicably being blocked, may well be hitting the
2082 HREF="actions-file.html#FILTER-BANNERS-BY-SIZE"
2085 >"+filter{banners-by-size}"</SPAN
2089 that images of certain sizes are ad banners (works well
2094 >most of the time</I
2096 > since these tend to be standardized).</P
2104 > is an alias that disables most
2105 actions that are the most likely to cause trouble. This can be used as a
2106 last resort for problem sites. </P
2117 # Handle with care: easy to break
2119 mybank.example.com</PRE
2129 >Remember to flush caches!</I
2135 > reference lacks the TLD portion (e.g.
2139 >). This will effectively match any TLD with
2143 > in it, such as <TT
2145 >mail.google.de.</TT
2147 just as an example.</P
2150 If this still does not work, you will have to go through the remaining
2151 actions one by one to find which one(s) is causing the problem.</P
2159 SUMMARY="Footer navigation table"