3 By: Junkbuster Developers
5 $Id: user-manual.txt,v 1.20 2002/03/03 01:33:50 hal9 Exp $
7 The user manual gives the users information on how to install and configure
8 Internet Junkbuster. Internet Junkbuster is an application that provides
9 privacy and security to users of the World Wide Web.
11 You can find the latest version of the user manual at http://
12 ijbswa.sourceforge.net/user-manual/.
14 Feel free to send a note to the developers at <
15 ijbswa-developers@lists.sourceforge.net>.
17 -------------------------------------------------------------------------------
33 3. Junkbuster Configuration
35 3.1. The Main Configuration File
37 3.1.1. Defining Other Configuration Files
38 3.1.2. Other Configuration Options
39 3.1.3. Access Control List (ACL)
41 3.1.5. Windows GUI Options
45 3.2.1. URL Domain and Path Syntax
52 4. Quickstart to Using Junkbuster
53 5. Contact the Developers
54 6. Copyright and History
62 8.1. Regular Expressions
66 Internet Junkbuster is a web proxy with advanced filtering capabilities for
67 protecting privacy, filtering and modifying web page content, managing cookies,
68 controlling access, and removing ads, banners, pop-ups and other obnoxious
69 Internet Junk. Junkbuster has a very flexible configuration and can be
70 customized to suit individual needs and tastes. Internet Junkbuster has
71 application for both stand-alone systems and multi-user networks.
73 This documentation is included with the current BETA version of Internet
74 Junkbuster and is incomplete at this point. The most up to date reference for
75 the time being is still the comments in the source files and in the individual
76 configuration files. Development of version 3.0 is currently nearing
77 completion, and includes many significant changes and enhancements over earlier
78 versions. The target release date for stable v3.0 RSN.
80 Since this is a BETA version, not all new features are well tested. This
81 documentation may be slightly out of sync as a result. And there may be bugs,
82 though hopefully not many!
84 -------------------------------------------------------------------------------
88 In addition to Junkbuster's traditional features of ad and banner blocking and
89 cookie management, this is a list of new features currently under development:
91 * Integrated browser based configuration and control utility (http://i.j.b).
92 Browser-based tracing of rule and filter effects.
94 * Modularized configuration that will allow for system wide settings, and
95 individual user settings. (not implemented yet, probably a 3.1 feature)
97 * Blocking of annoying pop-up browser windows.
99 * HTTP/1.1 compliant (most, but not all 1.1 features are supported).
101 * Support for Perl Compatible Regular Expressions in the configuration files,
102 and generally a more sophisticated and flexible configuration syntax over
107 * Web page content filtering (removes banners based on size, invisible
108 "web-bugs", JavaScript, pop-ups, status bar abuse, etc.)
110 * Bypass many click-tracking scripts (avoids script redirection).
112 * Multi-threaded (POSIX and native threads).
114 * Auto-detection and re-reading of config file changes.
116 * User-customizable HTML templates (e.g. 404 error page).
118 * Improved cookie management features (e.g. session based cookies).
120 * Builds from source on most UNIX-like systems. Packages available for: Linux
121 (RedHat, SuSE, or Debian), Windows, Sun Solaris, Mac OSX, OS/2.
123 * In addition, the configuration is much more powerful and versatile
126 -------------------------------------------------------------------------------
130 Junkbuster is available as raw source code, or pre-compiled binaries. See the
131 Junkbuster Home Page for current release info. Junkbuster is also available via
132 CVS. This is the recommended approach at this time. But please be aware that
133 CVS is constantly changing, and it may break in mysterious ways.
135 -------------------------------------------------------------------------------
139 For gzipped tar archives, unpack the source:
141 tar xzvf ijb_source_* [.tgz or .tar.gz]
142 cd ijb_source_2.9.10_beta
145 For retrieving the current CVS sources, you'll need the CVS package installed
146 first. To download CVS source:
148 cvs -d:pserver:anonymous@cvs.ijbswa.sourceforge.net:/cvsroot/ijbswa login
149 cvs -z3 -d:pserver:anonymous@cvs.ijbswa.sourceforge.net:/cvsroot/ijbswa co current
153 This will create a directory named current/, which will contain the source
156 Then, in either case, to build from tarball/CVS source:
158 ./configure (--help to see options)
159 make (the make from gnu, gmake for *BSD)
161 make -n install (to see where all the files will go)
162 make install (to really install)
165 For Redhat and SuSE Linux RPM packages, see below.
167 -------------------------------------------------------------------------------
171 To build Redhat RPM packages, install source as above. Then:
173 autoheader [suggested for CVS source]
174 autoconf [suggested for CVS source]
179 This will create both binary and src RPMs in the usual places. Example:
181 /usr/src/redhat/RPMS/i686/junkbuster-2.9.10-1.i686.rpm
183 /usr/src/redhat/SRPMS/junkbuster-2.9.10-1.src.rpm
185 To install, of course:
187 rpm -Uvv /usr/src/redhat/RPMS/i686/junkbuster-2.9.10-1.i686.rpm
190 This will place the Junkbuster configuration files in /etc/junkbuster/, and log
191 files in /var/log/junkbuster/.
193 -------------------------------------------------------------------------------
197 To build SuSE RPM packages, install source as above. Then:
199 autoheader [suggested for CVS source]
200 autoconf [suggested for CVS source]
205 This will create both binary and src RPMs in the usual places. Example:
207 /usr/src/packages/RPMS/i686/junkbuster-2.9.10-1.i686.rpm
209 /usr/src/packages/SRPMS/junkbuster-2.9.10-1.src.rpm
211 To install, of course:
213 rpm -Uvv /usr/src/packages/RPMS/i686/junkbuster-2.9.10-1.i686.rpm
216 This will place the Junkbuster configuration files in /etc/junkbuster/, and log
217 files in /var/log/junkbuster/.
219 -------------------------------------------------------------------------------
223 Junkbuster is packaged in a WarpIN self- installing archive. The
224 self-installing program will be named depending on the release version,
225 something like: ijbos2_setup_1.2.3.exe. In order to install it, simply run this
226 executable or double-click on its icon and follow the WarpIN installation
227 panels. A shadow of the Junkbuster executable will be placed in your startup
228 folder so it will start automatically whenever OS/2 starts.
230 The directory you choose to install Junkbuster into will contain all of the
233 If you would like to build binary images on OS/2 yourself, you will need a few
234 Unix-like tools: autoconf, autoheader and sh. These tools will be used to
235 create the required config.h file, which is not part of the source distribution
236 because it differs based on platform. You will also need a compiler. The
237 distribution has been created using IBM VisualAge compilers, but you can use
238 any compiler you like. GCC/EMX has the disadvantage of needing to be
239 single-threaded due to a limitation of EMX's implementation of the select()
242 In addition to needing the source code distribution as outlined earlier, you
243 will want to extract the os2seutp directory from CVS:
245 cvs -d:pserver:anonymous@cvs.ijbswa.sourceforge.net:/cvsroot/ijbswa login
246 cvs -z3 -d:pserver:anonymous@cvs.ijbswa.sourceforge.net:/cvsroot/ijbswa co os2setup
249 This will create a directory named os2setup/, which will contain the
250 Makefile.vac makefile and os2build.cmd which is used to completely create the
251 binary distribution. The sequence of events for building the executable for
252 yourself goes something like this:
259 nmake -f Makefile.vac
262 You will see this sequence laid out in os2build.cmd.
264 -------------------------------------------------------------------------------
268 Click-click. (I need help on this. Not a clue here. Also for configuration
271 -------------------------------------------------------------------------------
275 Some quick notes on other Operating Systems.
277 For FreeBSD (and other *BSDs?), the build will require gmake instead of the
278 included make. gmake is available from http://www.gnu.org. The rest should be
279 the same as above for Linux/Unix.
281 -------------------------------------------------------------------------------
283 3. Junkbuster Configuration
285 For Unix, *BSD and Linux, all configuration files are located in /etc/
286 junkbuster/ by default. For MS Windows, OS/2 and AmigaOS, these are all in the
287 same directory as the Junkbuster executable. The name and number of
288 configuration files has changed from previous versions, and is subject to
289 change as development progresses.
291 The installed defaults provide a reasonable starting point, though possibly
292 aggressive by some standards. For the time being, there are only three default
293 configuration files (this will change in time):
295 * The main configuration file is named config on Linux, Unix, BSD, OS/2,
296 and AmigaOS and config.txt on Windows.
298 * The ijb.action file is used to define various "actions" relating to images,
299 banners, pop-ups, access restrictions, banners and cookies. There is a CGI
300 based editor for this file that can be accessed via http://i.j.b. This is
301 the easiest method of configuring actions. (Other actions files are
302 included as well with differing levels of filtering and blocking, e.g.
305 * The re_filterfile file can be used to rewrite the raw page content,
306 including text as well as embedded HTML and JavaScript.
308 ijb.action and re_filterfile can use Perl style regular expressions for maximum
309 flexibility. All files use the "#" character to denote a comment. Such lines
310 are not processed by Junkbuster. After making any changes, there is no need to
311 restart Junkbuster in order for the changes to take effect. Junkbuster should
312 detect such changes automatically.
314 While under development, the configuration content is subject to change. The
315 below documentation may not be accurate by the time you read this. Also, what
316 constitutes a "default" setting, may change, so please check all your
317 configuration files on important issues.
319 -------------------------------------------------------------------------------
321 3.1. The Main Configuration File
323 Again, the main configuration file is named config on Linux/Unix/BSD and OS/2,
324 and config.txt on Windows. Configuration lines consist of an initial keyword
325 followed by a list of values, all separated by whitespace (any number of spaces
326 or tabs). For example:
328 blockfile blocklist.ini
331 Indicates that the blockfile is named "blocklist.ini".
333 A "#" indicates a comment. Any part of a line following a "#" is ignored,
334 except if the "#" is preceded by a "\".
336 Thus, by placing a "#" at the start of an existing configuration line, you can
337 make it a comment and it will be treated as if it weren't there. This is called
338 "commenting out" an option and can be useful to turn off features: If you
339 comment out the "logfile" line, junkbuster will not log to a file at all. Watch
340 for the "default:" section in each explanation to see what happens if the
341 option is left unset (or commented out).
343 Long lines can be continued on the next line by using a "\" as the very last
346 There are various aspects of Junkbuster behavior that can be tuned.
348 -------------------------------------------------------------------------------
350 3.1.1. Defining Other Configuration Files
352 Junkbuster can use a number of other files to tell it what ads to block, what
353 cookies to accept, etc. This section of the configuration file tells Junkbuster
354 where to find all those other files.
356 On Windows and AmigaOS, Junkbuster looks for these files in the same directory
357 as the executable. On Unix and OS/2, Junkbuster looks for these files in the
358 current working directory. In either case, an absolute path name can be used
361 When development goes modular and multi-user, the blocker, filter, and per-user
362 config will be stored in subdirectories of "confdir". For now, only confdir/
363 templates is used for storing HTML templates for CGI results.
365 The location of the configuration files:
367 confdir /etc/junkbuster # No trailing /, please.
370 The directory where all logging (i.e. logfile and jarfile) takes place. No
371 trailing "/", please:
373 logdir /var/log/junkbuster
376 Note that all file specifications below are relative to the above two
379 The "ijb.action" file contains patterns to specify the actions to apply to
380 requests for each site. Default: Cookies to and from all destinations are kept
381 only during the current browser session (i.e. they are not saved to disk).
382 Pop-ups are disabled for all sites. All sites are filtered if "re_filterfile"
383 specified. No sites are blocked. An empty image is displayed for filtered ads
384 and other images (formerly "tinygif"). The syntax of this file is explained in
387 actionsfile ijb.action
390 The "re_filterfile" file contains content modification rules. These rules
391 permit powerful changes on the content of Web pages, e.g., you could disable
392 your favorite JavaScript annoyances, rewrite the actual content, or just have
393 some fun replacing "Microsoft" with "MicroSuck" wherever it appears on a Web
394 page. Default: No content modification, or whatever the developers are playing
397 re_filterfile re_filterfile
400 The logfile is where all logging and error messages are written. The logfile
401 can be useful for tracking down a problem with Junkbuster (e.g., it's not
402 blocking an ad you think it should block) but in most cases you probably will
405 Your logfile will grow indefinitely, and you will probably want to periodically
406 remove it. On Unix systems, you can do this with a cron job (see "man cron").
407 For Redhat, a logrotate script has been included.
409 On SuSE Linux systems, you can place a line like "/var/log/junkbuster.* +1024k
410 644 nobody.nogroup" in /etc/logfiles, with the effect that cron.daily will
411 automatically archive, gzip, and empty the log, when it exceeds 1M size.
413 Default: Log to the a file named logfile. Comment out to disable logging.
418 The "jarfile" defines where Junkbuster stores the cookies it intercepts. Note
419 that if you use a "jarfile", it may grow quite large. Default: Don't store
425 If you specify a "trustfile", Junkbuster will only allow access to sites that
426 are named in the trustfile. You can also mark sites as trusted referrers, with
427 the effect that access to untrusted sites will be granted, if a link from a
428 trusted referrer was used. The link target will then be added to the
429 "trustfile". This is a very restrictive feature that typical users most
430 probably want to leave disabled. Default: Disabled, don't use the trust
436 If you use the trust mechanism, it is a good idea to write up some on-line
437 documentation about your blocking policy and to specify the URL(s) here. They
438 will appear on the page that your users receive when they try to access
439 untrusted content. Use multiple times for multiple URLs. Default: Don't display
440 links on the "untrusted" info page.
442 trust-info-url http://www.your-site.com/why_we_block.html
443 trust-info-url http://www.your-site.com/what_we_allow.html
446 -------------------------------------------------------------------------------
448 3.1.2. Other Configuration Options
450 This part of the configuration file contains options that control how
453 "Admin-address" should be set to the email address of the proxy administrator.
454 It is used in many of the proxy-generated pages. Default: fill@me.in.please.
456 #admin-address fill@me.in.please
459 "Proxy-info-url" can be set to a URL that contains more info about this
460 Junkbuster installation, it's configuration and policies. It is used in many of
461 the proxy-generated pages and its use is highly recommended in multi-user
462 installations, since your users will want to know why certain content is
463 blocked or modified. Default: Don't show a link to on-line documentation.
465 proxy-info-url http://www.your-site.com/proxy.html
468 "Listen-address" specifies the address and port where Junkbuster will listen
469 for connections from your Web browser. The default is to listen on the
470 localhost port 8000, and this is suitable for most users. (In your web browser,
471 under proxy configuration, list the proxy server as "localhost" and the port as
474 If you already have another service running on port 8000, or if you want to
475 serve requests from other machines (e.g. on your local network) as well, you
476 will need to override the default. The syntax is "listen-address
477 [<ip-address>]:<port>". If you leave out the IP address, junkbuster will bind
478 to all interfaces (addresses) on your machine and may become reachable from the
479 Internet. In that case, consider using access control lists (acl's) (see
480 "aclfile" above), or a firewall.
482 For example, suppose you are running Junkbuster on a machine which has the
483 address 192.168.0.1 on your local private network (192.168.0.0) and has another
484 outside connection with a different address. You want it to serve requests from
487 listen-address 192.168.0.1:8000
490 If you want it to listen on all addresses (including the outside connection):
495 If you do this, consider using ACLs (see "aclfile" above). Note: you will need
496 to point your browser(s) to the address and port that you have configured here.
497 Default: localhost:8000 (127.0.0.1:8000).
499 The debug option sets the level of debugging information to log in the logfile
500 (and to the console in the Windows version). A debug level of 1 is informative
501 because it will show you each request as it happens. Higher levels of debug are
502 probably only of interest to developers.
504 debug 1 # GPC = show each GET/POST/CONNECT request
505 debug 2 # CONN = show each connection status
506 debug 4 # IO = show I/O status
507 debug 8 # HDR = show header parsing
508 debug 16 # LOG = log all data into the logfile
509 debug 32 # FRC = debug force feature
510 debug 64 # REF = debug regular expression filter
511 debug 128 # = debug fast redirects
512 debug 256 # = debug GIF de-animation
513 debug 512 # CLF = Common Log Format
514 debug 1024 # = debug kill pop-ups
515 debug 4096 # INFO = Startup banner and warnings.
516 debug 8192 # ERROR = Non-fatal errors
519 It is highly recommended that you enable ERROR reporting (debug 8192), at least
520 until the next stable release.
522 The reporting of FATAL errors (i.e. ones which crash JunkBuster) is always on
523 and cannot be disabled.
525 If you want to use CLF (Common Log Format), you should set "debug 512" ONLY, do
526 not enable anything else.
528 Multiple "debug" directives, are OK - they're logical-OR'd together.
530 debug 15 # same as setting the first 4 listed above
537 debug 8192 # Errors - *we highly recommended enabling this*
540 Junkbuster normally uses "multi-threading", a software technique that permits
541 it to handle many different requests simultaneously. In some cases you may wish
542 to disable this -- particularly if you're trying to debug a problem. The
543 "single-threaded" option forces Junkbuster to handle requests sequentially.
544 Default: Multi-threaded mode.
549 "toggle" allows you to temporarily disable all Junkbuster's filtering. Just set
552 The Windows version of Junkbuster puts an icon in the system tray, which also
553 allows you to change this option. If you right-click on that icon (or select
554 the "Options" menu), one choice is "Enable". Clicking on enable toggles
555 Junkbuster on and off. This is useful if you want to temporarily disable
556 Junkbuster, e.g., to access a site that requires cookies which you would
557 otherwise have blocked. This can also be toggled via a web browser at the
558 Junkbuster internal address of http://i.j.b on any platform.
560 "toggle 1" means Junkbuster runs normally, "toggle 0" means that Junkbuster
561 becomes a non-anonymizing non-blocking proxy. Default: 1 (on).
566 For content filtering, i.e. the "+filter" and "+deanimate-gif" actions, it is
567 necessary that Junkbuster buffers the entire document body. This can be
568 potentially dangerous, since a server could just keep sending data indefinitely
569 and wait for your RAM to exhaust. With nasty consequences.
571 The buffer-limit option lets you set the maximum size in Kbytes that each
572 buffer may use. When the documents buffer exceeds this size, it is flushed to
573 the client unfiltered and no further attempt to filter the rest of it is made.
574 Remember that there may multiple threads running, which might require
575 increasing the "buffer-limit" Kbytes each, unless you have enabled
576 "single-threaded" above.
581 To enable the web-based ijb.action file editor set enable-edit-actions to 1, or
582 0 to disable. Note that you must have compiled JunkBuster with support for this
583 feature, otherwise this option has no effect. This internal page can be reached
586 Security note: If this is enabled, anyone who can use the proxy can edit the
587 actions file, and their changes will affect all users. For shared proxies, you
588 probably want to disable this. Default: enabled.
590 enable-edit-actions 1
593 Allow JunkBuster to be toggled on and off remotely, using your web browser. Set
594 "enable-remote-toggle"to 1 to enable, and 0 to disable. Note that you must have
595 compiled JunkBuster with support for this feature, otherwise this option has no
598 Security note: If this is enabled, anyone who can use the proxy can toggle it
599 on or off (see http://i.j.b), and their changes will affect all users. For
600 shared proxies, you probably want to disable this. Default: enabled.
602 enable-remote-toggle 1
605 -------------------------------------------------------------------------------
607 3.1.3. Access Control List (ACL)
609 Access controls are included at the request of some ISPs and systems
610 administrators, and are not usually needed by individual users. Please note the
611 warnings in the FAQ that this proxy is not intended to be a substitute for a
612 firewall or to encourage anyone to defer addressing basic security weaknesses.
614 If no access settings are specified, the proxy talks to anyone that connects.
615 If any access settings file are specified, then the proxy talks only to IP
616 addresses permitted somewhere in this file and not denied later in this file.
618 Summary -- if using an ACL:
620 Client must have permission to receive service.
622 LAST match in ACL wins.
624 Default behavior is to deny service.
626 The syntax for an entry in the Access Control List is:
628 ACTION SRC_ADDR[/SRC_MASKLEN] [ DST_ADDR[/DST_MASKLEN] ]
631 Where the individual fields are:
633 ACTION = "permit-access" or "deny-access"
635 SRC_ADDR = client hostname or dotted IP address
636 SRC_MASKLEN = number of bits in the subnet mask for the source
638 DST_ADDR = server or forwarder hostname or dotted IP address
639 DST_MASKLEN = number of bits in the subnet mask for the target
642 The field separator (FS) is whitespace (space or tab).
644 IMPORTANT NOTE: If the junkbuster is using a forwarder (see below) or a gateway
645 for a particular destination URL, the DST_ADDR that is examined is the address
646 of the forwarder or the gateway and NOT the address of the ultimate target.
647 This is necessary because it may be impossible for the local Junkbuster to
648 determine the address of the ultimate target (that's often what gateways are
651 Here are a few examples to show how the ACL features work:
653 "localhost" is OK -- no DST_ADDR implies that ALL destination addresses are OK:
655 permit-access localhost
658 A silly example to illustrate permitting any host on the class-C subnet with
659 Junkbuster to go anywhere:
661 permit-access www.junkbusters.com/24
664 Except deny one particular IP address from using it at all:
666 deny-access ident.junkbusters.com
669 You can also specify an explicit network address and subnet mask. Explicit
670 addresses do not have to be resolved to be used.
672 permit-access 207.153.200.0/24
675 A subnet mask of 0 matches anything, so the next line permits everyone.
677 permit-access 0.0.0.0/0
680 Note, you cannot say:
685 to allow all *.org domains. Every IP address listed must resolve fully.
687 An ISP may want to provide a Junkbuster that is accessible by "the world" and
688 yet restrict use of some of their private content to hosts on its internal
689 network (i.e. its own subscribers). Say, for instance the ISP owns the Class-B
690 IP address block 123.124.0.0 (a 16 bit netmask). This is how they could do it:
692 permit-access 0.0.0.0/0 0.0.0.0/0 # other clients can go anywhere
693 # with the following exceptions:
695 deny-access 0.0.0.0/0 123.124.0.0/16 # block all external requests for
696 # sites on the ISP's network
698 permit 0.0.0.0/0 www.my_isp.com # except for the ISP's main
701 permit 123.124.0.0/16 0.0.0.0/0 # the ISP's clients can go
705 Note that if some hostnames are listed with multiple IP addresses, the primary
706 value returned by DNS (via gethostbyname()) is used. Default: Anyone can access
709 -------------------------------------------------------------------------------
713 This feature allows chaining of HTTP requests via multiple proxies. It can be
714 used to better protect privacy and confidentiality when accessing specific
715 domains by routing requests to those domains to a special purpose filtering
716 proxy such as lpwa.com. Or to use a caching proxy to speed up browsing.
718 It can also be used in an environment with multiple networks to route requests
719 via multiple gateways allowing transparent access to multiple networks without
720 having to modify browser configurations.
722 Also specified here are SOCKS proxies. Junkbuster SOCKS 4 and SOCKS 4A. The
723 difference is that SOCKS 4A will resolve the target hostname using DNS on the
724 SOCKS server, not our local DNS client.
726 The syntax of each line is:
728 forward target_domain[:port] http_proxy_host[:port]
729 forward-socks4 target_domain[:port] socks_proxy_host[:port] http_proxy_host[:
731 forward-socks4a target_domain[:port] socks_proxy_host[:port] http_proxy_host[:
735 If http_proxy_host is ".", then requests are not forwarded to a HTTP proxy but
736 are made directly to the web servers.
738 Lines are checked in sequence, and the last match wins.
740 There is an implicit line equivalent to the following, which specifies that
741 anything not finding a match on the list is to go out without forwarding or
742 gateway protocol, like so:
744 forward .* . # implicit
747 In the following common configuration, everything goes to Lucent's LPWA, except
748 SSL on port 443 (which it doesn't handle):
750 forward .* lpwa.com:8000
754 See the FAQ for instructions on how to automate the login procedure for LPWA.
755 Some users have reported difficulties related to LPWA's use of "." as the last
756 element of the domain, and have said that this can be fixed with this:
758 forward lpwa. lpwa.com:8000
761 (NOTE: the syntax for specifying target_domain has changed since the previous
762 paragraph was written -- it will not work now. More information is welcome.)
764 In this fictitious example, everything goes via an ISP's caching proxy, except
765 requests to that ISP:
767 forward .* caching.myisp.net:8000
771 For the @home network, we're told the forwarding configuration is this:
773 forward .* proxy:8080
776 Also, we're told they insist on getting cookies and JavaScript, so you should
777 add home.com to the cookie file. We consider JavaScript a security risk. Java
780 In this example direct connections are made to all "internal" domains, but
781 everything else goes through Lucent's LPWA by way of the company's SOCKS
782 gateway to the Internet.
784 forward-socks4 .* lpwa.com:8000 firewall.my_company.com:1080
785 forward my_company.com .
788 This is how you could set up a site that always uses SOCKS but no forwarders:
790 forward-socks4a .* . firewall.my_company.com:1080
793 An advanced example for network administrators:
795 If you have links to multiple ISPs that provide various special content to
796 their subscribers, you can configure forwarding to pass requests to the
797 specific host that's connected to that ISP so that everybody can see all of the
798 content on all of the ISPs.
800 This is a bit tricky, but here's an example:
802 host-a has a PPP connection to isp-a.com. And host-b has a PPP connection to
803 isp-b.com. host-a can run a Junkbuster proxy with forwarding like this:
806 forward isp-b.com host-b:8000
809 host-b can run a Junkbuster proxy with forwarding like this:
812 forward isp-a.com host-a:8000
815 Now, anyone on the Internet (including users on host-a and host-b) can set
816 their browser's proxy to either host-a or host-b and be able to browse the
817 content on isp-a or isp-b.
819 Here's another practical example, for University of Kent at Canterbury students
820 with a network connection in their room, who need to use the University's Squid
823 forward *. ssbcache.ukc.ac.uk:3128 # Use the proxy, except for:
824 forward .ukc.ac.uk . # Anything on the same domain as us
825 forward * . # Host with no domain specified
826 forward 129.12.*.* . # A dotted IP on our /16 network.
827 forward 127.*.*.* . # Loopback address
828 forward localhost.localdomain . # Loopback address
829 forward www.ukc.mirror.ac.uk . # Specific host
832 If you intend to chain Junkbuster and squid locally, then chain as browser ->
833 squid -> junkbuster is the recommended way.
835 Your squid configuration could then look like this:
837 # Define junkbuster as parent cache
839 cache_peer 127.0.0.1 parent 8000 0 no-query
841 # Define ACL for protocol FTP
844 # Do not forward ACL FTP to junkbuster
845 always_direct allow FTP
847 # Do not forward ACL CONNECT (https) to junkbuster
848 always_direct allow CONNECT
850 # Forward the rest to junkbuster
851 never_direct allow all
854 -------------------------------------------------------------------------------
856 3.1.5. Windows GUI Options
858 Junkbuster has a number of options specific to the Windows GUI interface:
860 If "activity-animation" is set to 1, the Junkbuster icon will animate when
861 "Junkbuster" is active. To turn off, set to 0.
866 If "log-messages" is set to 1, Junkbuster will log messages to the console
872 If "log-buffer-size" is set to 1, the size of the log buffer, i.e. the amount
873 of memory used for the log messages displayed in the console window, will be
874 limited to "log-max-lines" (see below).
876 Warning: Setting this to 0 will result in the buffer to grow infinitely and eat
882 log-max-lines is the maximum number of lines held in the log buffer. See above.
887 If "log-highlight-messages" is set to 1, Junkbuster will highlight portions of
888 the log messages with a bold-faced font:
890 log-highlight-messages 1
893 The font used in the console window:
895 log-font-name Comic Sans MS
898 Font size used in the console window:
903 "show-on-task-bar" controls whether or not Junkbuster will appear as a button
904 on the Task bar when minimized:
909 If "close-button-minimizes" is set to 1, the Windows close button will minimize
910 Junkbuster instead of closing the program (close with the exit option on the
913 close-button-minimizes 1
916 The "hide-console" option is specific to the MS-Win console version of
917 JunkBuster. If this option is used, Junkbuster will disconnect from and hide
923 -------------------------------------------------------------------------------
925 3.2. The Actions File
927 The "ijb.action" file (formerly actionsfile) is used to define what actions
928 Junkbuster takes, and thus determines how images, cookies and various other
929 aspects of HTTP content and transactions are handled. Images can be anything
930 you want, including ads, banners, or just some obnoxious image that you would
931 rather not see. Cookies can be accepted or rejected, or accepted only during
932 the current browser session (i.e. not written to disk). Changes to ijb.action
933 should be immediately visible to Junkbuster without the need to restart.
935 To determine which actions apply to a request, the URL of the request is
936 compared to all patterns in this file. Every time it matches, the list of
937 applicable actions for the URL is incrementally updated. You can trace this
938 process by visiting http://i.j.b/show-url-info.
940 The actions file can be edited with a browser by loading http://i.j.b/, and
941 then select "Edit Actions".
943 There are four types of lines in this file: comments (begin with a "#"
944 character), actions, aliases and patterns, all of which are explained below, as
945 well as the configuration file syntax that Junkbuster understands.
947 -------------------------------------------------------------------------------
949 3.2.1. URL Domain and Path Syntax
951 Generally, a pattern has the form <domain>/<path>, where both the <domain> and
952 <path> part are optional. If you only specify a domain part, the "/" can be
955 www.example.com - is a domain only pattern and will match any request to
958 www.example.com/ - means exactly the same.
960 www.example.com/index.html - matches only the single document "/index.html" on
963 /index.html - matches the document "/index.html", regardless of the domain.
965 index.html - matches nothing, since it would be interpreted as a domain name
966 and there is no top-level domain called ".html".
968 The matching of the domain part offers some flexible options: if the domain
969 starts or ends with a dot, it becomes unanchored at that end. For example:
971 .example.com - matches any domain that ENDS in ".example.com".
973 www. - matches any domain that STARTS with "www".
975 Additionally, there are wild-cards that you can use in the domain names
976 themselves. They work pretty similar to shell wild-cards: "*" stands for zero
977 or more arbitrary characters, "?" stands for any single character. And you can
978 define character classes in square brackets and they can be freely mixed:
980 ad*.example.com - matches "adserver.example.com", "ads.example.com", etc but
981 not "sfads.example.com".
983 *ad*.example.com - matches all of the above, and then some.
985 .?pix.com - matches "www.ipix.com", "pictures.epix.com", "a.b.c.d.e.upix.com",
988 www[1-9a-ez].example.com - matches "www1.example.com", "www4.example.com",
989 "wwwd.example.com", "wwwz.example.com", etc., but not "wwww.example.com".
991 If Junkbuster was compiled with "pcre" support (default), Perl compatible
992 regular expressions can be used. See the pcre/docs/ directory or "man perlre"
993 (also available on http://www.perldoc.com/perl5.6/pod/perlre.html) for details.
994 A brief discussion of regular expressions is in the Appendix. For instance:
996 /.*/advert[0-9]+\.jpe?g - would match a URL from any domain, with any path that
997 includes "advert" followed immediately by one or more digits, then a "." and
998 ending in either "jpeg" or "jpg". So we match "example.com/ads/advert2.jpg",
999 and "www.example.com/ads/banners/advert39.jpeg", but not "www.example.com/ads/
1000 banners/advert39.gif" (no gifs in the example pattern).
1002 Please note that matching in the path is case INSENSITIVE by default, but you
1003 can switch to case sensitive at any point in the pattern by using the "(?-i)"
1006 www.example.com/(?-i)PaTtErN.* - will match only documents whose path starts
1007 with "PaTtErN" in exactly this capitalization.
1009 -------------------------------------------------------------------------------
1013 Actions are enabled if preceded with a "+", and disabled if preceded with a
1014 "-". Actions are invoked by enclosing the action name in curly braces (e.g.
1015 {+some_action}), followed by a list of URLs to which the action applies. There
1016 are three classes of actions:
1018 * Boolean (e.g. "+/-block"):
1020 {+name} # enable this action
1021 {-name} # disable this action
1024 * parameterized (e.g. "+/-hide-user-agent"):
1026 {+name{param}} # enable action and set parameter to "param"
1027 {-name} # disable action
1030 * Multi-value (e.g. "{+/-add-header{Name: value}}", "{+/-wafer{name=value}}
1033 {+name{param}} # enable action and add parameter "param"
1034 {-name{param}} # remove the parameter "param"
1035 {-name} # disable this action totally
1038 If nothing is specified in this file, no "actions" are taken. So in this case
1039 JunkBuster would just be a normal, non-blocking, non-anonymizing proxy. You
1040 must specifically enable the privacy and blocking features you need (although
1041 the provided default ijb.action file will give a good starting point).
1043 Later defined actions always over-ride earlier ones. For multi-valued actions,
1044 the actions are applied in the order they are specified.
1046 The list of valid Junkbuster "actions" are:
1048 * Add the specified HTTP header, which is not checked for validity. You may
1049 specify this many times to specify many different headers:
1051 +add-header{Name: value}
1054 * Block this URL totally.
1059 * De-animate all animated GIF images, i.e. reduce them to their last frame.
1060 This will also shrink the images considerably (in bytes, not pixels!). If
1061 the option "first" is given, the first frame of the animation is used as
1062 the replacement. If "last" is given, the last frame of the animation is
1063 used instead, which probably makes more sense for most banner animations,
1064 but also has the risk of not showing the entire last frame (if it is only a
1065 delta to an earlier frame).
1067 +deanimate-gifs{last}
1068 +deanimate-gifs{first}
1071 * "+downgrade" will downgrade HTTP/1.1 client requests to HTTP/1.0 and
1072 downgrade the responses as well. Use this action for servers that use HTTP/
1073 1.1 protocol features that Junkbuster doesn't handle well yet. HTTP/1.1 is
1074 only partially implemented. Default is not to downgrade requests.
1079 * Many sites, like yahoo.com, don't just link to other sites. Instead, they
1080 will link to some script on their own server, giving the destination as a
1081 parameter, which will then redirect you to the final target. URLs resulting
1082 from this scheme typically look like: http://some.place/some_script?http://
1085 Sometimes, there are even multiple consecutive redirects encoded in the
1086 URL. These redirections via scripts make your web browsing more traceable,
1087 since the server from which you follow such a link can see where you go to.
1088 Apart from that, valuable bandwidth and time is wasted, while your browser
1089 ask the server for one redirect after the other. Plus, it feeds the
1092 The "+fast-redirects" option enables interception of these requests by
1093 Junkbuster, who will cut off all but the last valid URL in the request and
1094 send a local redirect back to your browser without contacting the remote
1100 * Filter the website through the re_filterfile:
1105 * Block any existing X-Forwarded-for header, and do not add a new one:
1110 * If the browser sends a "From:" header containing your e-mail address, this
1111 either completely removes the header ("block"), or changes it to the
1112 specified e-mail address.
1115 +hide-from{spam@sittingduck.xqq}
1118 * Don't send the "Referer:" (sic) header to the web site. You can block it,
1119 forge a URL to the same server as the request (which is preferred because
1120 some sites will not send images otherwise) or set it to a constant string
1123 +hide-referer{block}
1124 +hide-referer{forge}
1125 +hide-referer{http://nowhere.com}
1128 * Alternative spelling of "+hide-referer". It has the same parameters, and
1129 can be freely mixed with, "+hide-referer". ("referrer" is the correct
1130 English spelling, however the HTTP specification has a bug - it requires it
1131 to be spelled "referer".)
1136 * Change the "User-Agent:" header so web servers can't tell your browser
1137 type. Warning! This breaks many web sites. Specify the user-agent value you
1138 want. Example, pretend to be using Netscape on Linux:
1140 +hide-user-agent{Mozilla (X11; I; Linux 2.0.32 i586)}
1143 * Treat this URL as an image. This only matters if it's also "+block"ed, in
1144 which case a "blocked" image can be sent rather than a HTML page. See
1145 "+image-blocker{}" below for the control over what is actually sent.
1150 * Decides what to do with URLs that end up tagged with "{+block +image}".
1151 There are 4 options. "-image-blocker" will send a HTML "blocked" page,
1152 usually resulting in a "broken image" icon. "+image-blocker{logo}" will
1153 send a "JunkBuster" image. "+image-blocker{blank}" will send a 1x1
1154 transparent GIF image. And finally, "+image-blocker{http://xyz.com}" will
1155 send a HTTP temporary redirect to the specified image. This has the
1156 advantage of the icon being being cached by the browser, which will speed
1159 +image-blocker{logo}
1160 +image-blocker{blank}
1161 +image-blocker{http://i.j.b/send-banner}
1164 * By default (i.e. in the absence of a "+limit-connect" action), Junkbuster
1165 will only allow CONNECT requests to port 443, which is the standard port
1166 for https as a precaution.
1168 The CONNECT methods exists in HTTP to allow access to secure websites
1169 (https:// URLs) through proxies. It works very simply: the proxy connects
1170 to the server on the specified port, and then short-circuits its
1171 connections to the client and to the remote proxy. This can be a big
1172 security hole, since CONNECT-enabled proxies can be abused as TCP relays
1175 If you want to allow CONNECT for more ports than this, or want to forbid
1176 CONNECT altogether, you can specify a comma separated list of ports and
1177 port ranges (the latter using dashes, with the minimum defaulting to 0 and
1180 +limit-connect{443} # This is the default and need no be specified.
1181 +limit-connect{80,443} # Ports 80 and 443 are OK.
1182 +limit-connect{-3, 7, 20-100, 500-} # Port less than 3, 7, 20 to 100
1183 #and above 500 are OK.
1186 * "+no-compression" prevents the website from compressing the data. Some
1187 websites do this, which can be a problem for Junkbuster, since "+filter",
1188 "+no-popup" and "+gif-deanimate" will not work on compressed data. This
1189 will slow down connections to those websites, though. Default is
1190 "nocompression" is turned on.
1195 * If the website sets cookies, "no-cookies-keep" will make sure they are
1196 erased when you exit and restart your web browser. This makes profiling
1197 cookies useless, but won't break sites which require cookies so that you
1198 can log in for transactions. Default: on.
1203 * Prevent the website from reading cookies:
1208 * Prevent the website from setting cookies:
1213 * Filter the website through a built-in filter to disable those obnoxious
1214 JavaScript pop-up windows via window.open(), etc. The two alternative
1215 spellings are equivalent.
1221 * This action only applies if you are using a jarfile for saving cookies. It
1222 sends a cookie to every site stating that you do not accept any copyright
1223 on cookies sent to you, and asking them not to track you. Of course, this
1224 is a (relatively) unique header they could use to track you.
1229 * This allows you to add an arbitrary cookie. It can be specified multiple
1230 times in order to add as many cookies as you like.
1235 The meaning of any of the above is reversed by preceding the action with a "-",
1236 in place of the "+".
1240 Turn off cookies by default, then allow a few through for specified sites:
1242 # Turn off all persistent cookies
1243 { +no-cookies-read }
1245 # Allow cookies for this browser session ONLY
1246 { +no-cookies-keep }
1248 # Exceptions to the above, sites that benefit from persistent cookies
1249 { -no-cookies-read }
1251 { -no-cookies-keep }
1258 # Alternative way of saying the same thing
1259 {-no-cookies-set -no-cookies-read -no-cookies-keep}
1264 Now turn off "fast redirects", and then we allow two exceptions:
1269 # Reverse it for these two sites, which don't work right without it.
1271 www.ukc.ac.uk/cgi-bin/wac\.cgi\?
1275 Turn on page filtering, with one exception for sourceforge:
1277 # Run everything through the default filter file (re_filterfile):
1280 # But please don't re_filter code from sourceforge!
1282 .cvs.sourceforge.net
1285 Now some URLs that we want "blocked", ie we won't see them. Many of these use
1286 regular expressions that will expand to match multiple URLs:
1290 /.*/(.*[-_.])?ads?[0-9]?(/|[-_.].*|\.(gif|jpe?g))
1291 /.*/(.*[-_.])?count(er)?(\.cgi|\.dll|\.exe|[?/])
1292 /.*/(ng)?adclient\.cgi
1293 /.*/(plain|live|rotate)[-_.]?ads?/
1294 /.*/(sponsor)s?[0-9]?/
1295 /.*/_?(plain|live)?ads?(-banners)?/
1297 /.*/ad(sdna_image|gifs?)/
1298 /.*/ad(server|stream|juggler)\.(cgi|pl|dll|exe)
1302 /.*/adv((er)?ts?|ertis(ing|ements?))?/
1306 /.*/cgi-bin/centralad/getimage
1307 /.*/images/addver\.gif
1308 /.*/images/marketing/.*\.(gif|jpe?g)
1312 /.*/sponsors?[0-9]?/
1313 /.*/advert[0-9]+\.jpg
1320 /graphics/defaultAd/
1322 /image\.ng/transactionID
1323 /images/.*/.*_anim\.gif # alvin brattli
1324 /ip_img/.*\.(gif|jpe?g)
1328 /cgi-bin/nph-adclick.exe/
1329 /.*/Image/BannerAdvertising/
1331 /.*/adlib/server\.cgi
1335 -------------------------------------------------------------------------------
1339 Custom "actions", known to Junkbuster as "aliases", can be defined by combining
1340 other "actions". These can in turn be invoked just like the built-in "actions".
1341 Currently, an alias can contain any character except space, tab, "=", "{" or "}
1342 ". But please use only "a"- "z", "0"-"9", "+", and "-". Alias names are not
1343 case sensitive, and must be defined before anything else in the ijb.actionfile
1344 ! And there can only be one set of "aliases" defined.
1346 Now let's define a few aliases:
1348 # Useful customer aliases we can use later. These must come first!
1350 +no-cookies = +no-cookies-set +no-cookies-read
1351 -no-cookies = -no-cookies-set -no-cookies-read
1353 -block -no-cookies -filter -fast-redirects -hide-referer -no-popups
1354 shop = -no-cookies -filter -fast-redirects
1355 +imageblock = +block +image
1357 #For people who don't like to type too much: ;-)
1360 c2 = -no-cookies-set +no-cookies-read
1361 c3 = +no-cookies-set -no-cookies-read
1362 #... etc. Customize to your heart's content.
1365 Some examples using our "shop" and "fragile" aliases from above:
1367 # These sites are very complex and require
1368 # minimal interference.
1370 .office.microsoft.com
1371 .windowsupdate.microsoft.com
1374 # Shopping sites - still want to block ads.
1377 .worldpay.com # for quietpc.com
1381 # These shops require pop-ups
1387 -------------------------------------------------------------------------------
1389 3.3. The Filter File
1391 The filter file defines what filtering of web pages Junkbuster does. The
1392 default filter file is re_filterfile, located in the config directory. In this
1393 file, any document content, whether viewable text or embedded non-visible
1394 content, can be changed.
1396 This file uses regular expressions to alter or remove any string in the target
1397 page. Some examples from the included default re_filterfile:
1399 Stop web pages from displaying annoying messages in the status bar by deleting
1402 # The status bar is for displaying link targets, not pointless buzzwords.
1403 # Again, check it out on http://www.airport-cgn.de/.
1404 s/status='.*?';*//ig
1407 Just for kicks, replace any occurrence of "Microsoft" with "MicroSuck":
1409 s/microsoft(?!.com)/MicroSuck/ig
1412 Kill those auto-refresh tags:
1414 # Kill refresh tags. I like to refresh myself. Manually.
1415 # check it out on http://www.airport-cgn.de/ and go to the arrivals page.
1417 s/<meta[^>]*http-equiv[^>]*refresh.*URL=([^>]*?)"?>/<link rev="x-refresh" href
1419 s/<meta[^>]*http-equiv="?page-enter"?[^>]*content=[^>]*>/<!
1420 --no page enter for me-->/i
1423 -------------------------------------------------------------------------------
1427 When Junkbuster displays one of its internal pages, such as a 404 Not Found
1428 error page, it uses the appropriate template. On Linux, BSD, and Unix, these
1429 are locate in /etc/junkbuster/templates by default. These may be customized, if
1432 -------------------------------------------------------------------------------
1434 4. Quickstart to Using Junkbuster
1436 Install package, then run and enjoy! JunkBuster accepts only one command line
1437 option -- the configuration file to be used. Example Unix startup command:
1440 # /usr/sbin/junkbuster /etc/junkbuster/config
1444 An init script is provided for SuSE and Redhat.
1446 For for SuSE: /etc/rc.d/junkbuster start
1448 For RedHat: /etc/rc.d/init.d/junkbuster start
1450 If no configuration file is specified on the command line, Junkbuster will look
1451 for a file named config in the current directory. Except on Win32 where it will
1452 try config.txt. If no file is specified on the command line and no default
1453 configuration file can be found, Junkbuster will fail to start.
1455 Be sure your browser is set to use the proxy which is by default at localhost,
1456 port 8000. With Netscape (and Mozilla), this can be set under Edit ->
1457 Preferences -> Advanced -> Proxies -> HTTP Proxy. For Internet Explorer: Tools
1458 > Internet Properties -> Connections -> LAN Setting. Then, check "Use Proxy"
1459 and fill in the appropriate info (Address: localhost, Port: 8000). Include if
1460 HTTPS proxy support too.
1462 The included default configuration files should give a reasonable starting
1463 point, though may be somewhat aggressive in blocking junk. You will probably
1464 want to keep an eye out for sites that require persistent cookies, and add
1465 these to ijb.action as needed. By default, most of these will be accepted only
1466 during the current browser session, until you add them to the configuration. If
1467 you want the browser to handle this instead, you will need to edit ijb.action
1468 and disable this feature. If you use more than one browser, it would make more
1469 sense to let Junkbuster handle this. In which case, the browser(s) should be
1470 set to accept all cookies.
1472 If a particular site shows problems loading properly, try adding it to the
1473 {fragile} section of ijb.action. This will turn off most actions for this site.
1475 HTTP/1.1 support is not fully implemented. If browsers that support HTTP/1.1
1476 (like Mozilla or recent versions of I.E.) experience problems, you might try to
1477 force HTTP/1.0 compatibility. For Mozilla, look under Edit -> Preferences ->
1478 Debug -> Networking. Or set the "+downgrade" config option in ijb.action.
1480 After running Junkbuster for a while, you can start to fine tune the
1481 configuration to suit your personal, or site, preferences and requirements.
1482 There are many, many aspects that can be customized. "Actions" (as specified in
1483 ijb.action) can be adjusted by pointing your browser to http://i.j.b/, and then
1484 follow the link to "edit the actions list". (This is an internal page and does
1485 not require Internet access.)
1487 In fact, various aspects of Junkbuster configuration can be viewed from this
1488 page, including current configuration parameters, source code version numbers,
1489 the browser's request headers, and "actions" that apply to a given URL. In
1490 addition to the ijb.action file editor mentioned above, Junkbuster can also be
1491 turned "on" and "off" from this page.
1493 If you encounter problems, please verify it is a Junkbuster bug, by disabling
1494 Junkbuster, and then trying the same page. Also, try another browser if
1495 possible to eliminate browser or site problems. Before reporting it as a bug,
1496 see if there is not a configuration option that is enabled that is causing the
1497 page not to load. You can then add an exception for that page or site. If a
1498 bug, please report it to the developers (see below).
1500 -------------------------------------------------------------------------------
1502 5. Contact the Developers
1504 Feature requests and other questions should be posted to the Feature request
1505 page at SourceForge. There is also an archive there.
1507 Anyone interested in actively participating in development and related
1508 discussions can join the appropriate mailing list here. Archives are available
1511 Please report bugs, using the form at Sourceforge. Please try to verify that it
1512 is a Junkbuster bug, and not a browser or site bug first. Also, check to make
1513 sure this is not already a known bug.
1515 -------------------------------------------------------------------------------
1517 6. Copyright and History
1521 Internet Junkbuster is free software; you can redistribute it and/or modify it
1522 under the terms of the GNU General Public License as published by the Free
1523 Software Foundation; either version 2 of the License, or (at your option) any
1526 This program is distributed in the hope that it will be useful, but WITHOUT ANY
1527 WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A
1528 PARTICULAR PURPOSE. See the GNU General Public License for more details, which
1529 is available from the Free Software Foundation, Inc, 59 Temple Place - Suite
1530 330, Boston, MA 02111-1307, USA.
1532 -------------------------------------------------------------------------------
1536 Junkbuster was originally written by Anonymous Coders and Junkbuster's
1537 Corporation, and was released as free open-source software under the GNU GPL.
1538 Stefan Waldherr made many improvements, and started the SourceForge project to
1539 rekindle development. The last stable release was v2.0.2, which has now grown
1542 -------------------------------------------------------------------------------
1546 http://sourceforge.net/projects/ijbswa
1548 http://ijbswa.sourceforge.net/
1552 http://www.junkbusters.com/ht/en/cookies.html
1554 http://www.waldherr.org/junkbuster/
1556 http://privacy.net/analyze/
1558 http://www.squid-cache.org/
1562 -------------------------------------------------------------------------------
1566 8.1. Regular Expressions
1568 Junkbuster can use "regular expressions" in various config files. Assuming
1569 support for "pcre" (Perl Compatible Regular Expressions) is compiled in, which
1570 is the default. Such configuration directives do not require regular
1571 expressions, but they can be used to increase flexibility by matching a pattern
1572 with wild-cards against URLs.
1574 If you are reading this, you probably don't understand what "regular
1575 expressions" are, or what they can do. So this will be a very brief
1576 introduction only. A full explanation would require a book ;-)
1578 "Regular expressions" is a way of matching one character expression against
1579 another to see if it matches or not. One of the "expressions" is a literal
1580 string of readable characters (letter, numbers, etc), and the other is a
1581 complex string of literal characters combined with wild-cards, and other
1582 special characters, called meta-characters. The "meta-characters" have special
1583 meanings and are used to build the complex pattern to be matched against. Perl
1584 Compatible Regular Expressions is an enhanced form of the regular expression
1585 language with backward compatibility.
1587 To make a simple analogy, we do something similar when we use wild-card
1588 characters when listing files with the dir command in DOS. *.* matches all
1589 filenames. The "special" character here is the asterisk which matches any and
1590 all characters. We can be more specific and use ? to match just individual
1591 characters. So "dir file?.text" would match "file1.txt", "file2.txt", etc. We
1592 are pattern matching, using a similar technique to "regular expressions"!
1594 Regular expressions do essentially the same thing, but are much, much more
1595 powerful. There are many more "special characters" and ways of building complex
1596 patterns however. Let's look at a few of the common ones, and then some
1599 . - Matches any single character, e.g. "a", "A", "4", ":", or "@".
1601 ? - The preceding character or expression is matched ZERO or ONE times. Either/
1604 + - The preceding character or expression is matched ONE or MORE times.
1606 * - The preceding character or expression is matched ZERO or MORE times.
1608 \ - The "escape" character denotes that the following character should be taken
1609 literally. This is used where one of the special characters (e.g. ".") needs to
1610 be taken literally and not as a special meta-character.
1612 [] - Characters enclosed in brackets will be matched if any of the enclosed
1613 characters are encountered.
1615 () - parentheses are used to group a sub-expression, or multiple
1618 | - The "bar" character works like an "or" conditional statement. A match is
1619 successful if the sub-expression on either side of "|" matches.
1621 s/string1/string2/g - This is used to rewrite strings of text. "string1" is
1622 replaced by "string2" in this example.
1624 These are just some of the ones you are likely to use when matching URLs with
1625 Junkbuster, and is a long way from a definitive list. This is enough to get us
1626 started with a few simple examples which may be more illuminating:
1628 /.*/banners/.* - A simple example that uses the common combination of "." and "
1629 *" to denote any character, zero or more times. In other words, any string at
1630 all. So we start with a literal forward slash, then our regular expression
1631 pattern (".*") another literal forward slash, the string "banners", another
1632 forward slash, and lastly another ".*". We are building a directory path here.
1633 This will match any file with the path that has a directory named "banners" in
1634 it. The ".*" matches any characters, and this could conceivably be more forward
1635 slashes, so it might expand into a much longer looking path. For example, this
1636 could match: "/eye/hate/spammers/banners/annoy_me_please.gif", or just "/
1637 banners/annoying.html", or almost an infinite number of other possible
1638 combinations, just so it has "banners" in the path somewhere.
1640 A now something a little more complex:
1642 /.*/adv((er)?ts?|ertis(ing|ements?))?/ - We have several literal forward
1643 slashes again ("/"), so we are building another expression that is a file path
1644 statement. We have another ".*", so we are matching against any conceivable
1645 sub-path, just so it matches our expression. The only true literal that must
1646 match our pattern is adv, together with the forward slashes. What comes after
1647 the "adv" string is the interesting part.
1649 Remember the "?" means the preceding expression (either a literal character or
1650 anything grouped with "(...)" in this case) can exist or not, since this means
1651 either zero or one match. So "((er)?ts?|ertis(ing|ements?))" is optional, as
1652 are the individual sub-expressions: "(er)", "(ing|ements?)", and the "s". The "
1653 |" means "or". We have two of those. For instance, "(ing|ements?)", can expand
1654 to match either "ing" OR "ements?". What is being done here, is an attempt at
1655 matching as many variations of "advertisement", and similar, as possible. So
1656 this would expand to match just "adv", or "advert", or "adverts", or
1657 "advertising", or "advertisement", or "advertisements". You get the idea. But
1658 it would not match "advertizements" (with a "z"). We could fix that by changing
1659 our regular expression to: "/.*/adv((er)?ts?|erti(s|z)(ing|ements?))?/", which
1660 would then match either spelling.
1662 /.*/advert[0-9]+\.(gif|jpe?g) - Again another path statement with forward
1663 slashes. Anything in the square brackets "[]" can be matched. This is using
1664 "0-9" as a shorthand expression to mean any digit one through nine. It is the
1665 same as saying "0123456789". So any digit matches. The "+" means one or more of
1666 the preceding expression must be included. The preceding expression here is
1667 what is in the square brackets -- in this case, any digit one through nine.
1668 Then, at the end, we have a grouping: "(gif|jpe?g)". This includes a "|", so
1669 this needs to match the expression on either side of that bar character also. A
1670 simple "gif" on one side, and the other side will in turn match either "jpeg"
1671 or "jpg", since the "?" means the letter "e" is optional and can be matched
1672 once or not at all. So we are building an expression here to match image GIF or
1673 JPEG type image file. It must include the literal string "advert", then one or
1674 more digits, and a "." (which is now a literal, and not a special character,
1675 since it is escaped with "\"), and lastly either "gif", or "jpeg", or "jpg".
1676 Some possible matches would include: "//advert1.jpg", "/nasty/ads/
1677 advert1234.gif", "/banners/from/hell/advert99.jpg". It would not match
1678 "advert1.gif" (no leading slash), or "/adverts232.jpg" (the expression does not
1679 include an "s"), or "/advert1.jsp" ("jsp" is not in the expression anywhere).
1681 s/microsoft(?!.com)/MicroSuck/i - This is a substitution. "MicroSuck" will
1682 replace any occurrence of "microsoft". The "i" at the end of the expression
1683 means ignore case. The "(?!.com)" means the match should fail if "microsoft" is
1684 followed by ".com". In other words, this acts like a "NOT" modifier. In case
1685 this is a hyperlink, we don't want to break it ;-).
1687 We are barely scratching the surface of regular expressions here so that you
1688 can understand the default Junkbuster configuration files, and maybe use this
1689 knowledge to customize your own installation. There is much, much more that can
1690 be done with regular expressions. Now that you know enough to get started, you
1691 can learn more on your own :/
1693 More reading on Perl Compatible Regular expressions: http://www.perldoc.com/
1694 perl5.6/pod/perlre.html