3 By: Junkbuster Developers
5 $Id: user-manual.sgml,v 1.29 2002/03/02 20:34:07 david__schmidt 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 web page content, managing cookies, controlling
68 access, and removing ads, banners, pop-ups and other obnoxious Internet Junk.
69 Junkbuster has a very flexible configuration and can be customized to suit
70 individual needs and tastes. Internet Junkbuster has application for both
71 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
250 This will create a directory named os2setup/, which will contain the
251 Makefile.vac makefile and os2build.cmd which is used to completely create the
252 binary distribution. The sequence of events for building the executable for
253 yourself goes something like this:
260 nmake -f Makefile.vac
263 You will see this sequence laid out in os2build.cmd.
265 -------------------------------------------------------------------------------
269 Click-click. (I need help on this. Not a clue here. Also for configuration
272 -------------------------------------------------------------------------------
276 Some quick notes on other Operating Systems.
278 For FreeBSD (and other *BSDs?), the build will require gmake instead of the
279 included make. gmake is available from http://www.gnu.org. The rest should be
280 the same as above for Linux/Unix.
282 -------------------------------------------------------------------------------
284 3. Junkbuster Configuration
286 For Unix, *BSD and Linux, all configuration files are located in /etc/
287 junkbuster/ by default. For MS Windows and OS/2, these are all in the same
288 directory as the Junkbuster executable. The name and number of configuration
289 files has changed from previous versions, and is subject to change as
290 development progresses.
292 The installed defaults provide a reasonable starting point, though possibly
293 aggressive by some standards. For the time being, there are only three default
294 configuration files (this will change in time):
296 * The main configuration file is named config on Linux, Unix, BSD, and OS/2,
297 and config.txt on Windows. On Amiga, it is AmiTCP:db/junkbuster/config.
299 * The ijb.action file is used to define various "actions" relating to images,
300 banners, pop-ups, access restrictions, banners and cookies. There is a CGI
301 based editor for this file that can be accessed via http://i.j.b. This is
302 the easiest method of configuring actions. (Other actions files are
303 included as well with differing levels of filtering and blocking, e.g.
306 * The re_filterfile file can be used to rewrite the raw page content,
307 including text as well as embedded HTML and JavaScript.
309 ijb.action and re_filterfile can use Perl style regular expressions for maximum
310 flexibility. All files use the "#" character to denote a comment. Such lines
311 are not processed by Junkbuster. After making any changes, there is no need to
312 restart Junkbuster in order for the changes to take effect. Junkbuster should
313 detect such changes automatically.
315 While under development, the configuration content is subject to change. The
316 below documentation may not be accurate by the time you read this. Also, what
317 constitutes a "default" setting, may change, so please check all your
318 configuration files on important issues.
320 -------------------------------------------------------------------------------
322 3.1. The Main Configuration File
324 Again, the main configuration file is named config on Linux/Unix/BSD and OS/2,
325 and config.txt on Windows. Configuration lines consist of an initial keyword
326 followed by a list of values, all separated by whitespace (any number of spaces
327 or tabs). For example:
329 blockfile blocklist.ini
332 Indicates that the blockfile is named "blocklist.ini".
334 A "#" indicates a comment. Any part of a line following a "#" is ignored,
335 except if the "#" is preceded by a "\".
337 Thus, by placing a "#" at the start of an existing configuration line, you can
338 make it a comment and it will be treated as if it weren't there. This is called
339 "commenting out" an option and can be useful to turn off features: If you
340 comment out the "logfile" line, junkbuster will not log to a file at all. Watch
341 for the "default:" section in each explanation to see what happens if the
342 option is left unset (or commented out).
344 Long lines can be continued on the next line by using a "\" as the very last
347 There are various aspects of Junkbuster behavior that can be tuned.
349 -------------------------------------------------------------------------------
351 3.1.1. Defining Other Configuration Files
353 Junkbuster can use a number of other files to tell it what ads to block, what
354 cookies to accept, etc. This section of the configuration file tells Junkbuster
355 where to find all those other files.
357 On Windows, Junkbuster looks for these files in the same directory as the
358 executable. On Unix and OS/2, Junkbuster looks for these files in the current
359 working directory. In either case, an absolute path name can be used to avoid
362 When development goes modular and multi-user, the blocker, filter, and per-user
363 config will be stored in subdirectories of "confdir". For now, only confdir/
364 templates is used for storing HTML templates for CGI results.
366 The location of the configuration files:
368 confdir /etc/junkbuster # No trailing /, please.
371 The directory where all logging (i.e. logfile and jarfile) takes place. No
372 trailing "/", please:
374 logdir /var/log/junkbuster
377 Note that all file specifications below are relative to the above two
380 The "ijb.action" file contains patterns to specify the actions to apply to
381 requests for each site. Default: Cookies to and from all destinations are kept
382 only during the current browser session (i.e. they are not saved to disk).
383 Pop-ups are disabled for all sites. All sites are filtered if "re_filterfile"
384 specified. No sites are blocked. An empty image is displayed for filtered ads
385 and other images (formerly "tinygif"). The syntax of this file is explained in
388 actionsfile ijb.action
391 The "re_filterfile" file contains content modification rules. These rules
392 permit powerful changes on the content of Web pages, e.g., you could disable
393 your favorite JavaScript annoyances, rewrite the actual content, or just have
394 some fun replacing "Microsoft" with "MicroSuck" wherever it appears on a Web
395 page. Default: No content modification, or whatever the developers are playing
398 re_filterfile re_filterfile
401 The logfile is where all logging and error messages are written. The logfile
402 can be useful for tracking down a problem with Junkbuster (e.g., it's not
403 blocking an ad you think it should block) but in most cases you probably will
406 Your logfile will grow indefinitely, and you will probably want to periodically
407 remove it. On Unix systems, you can do this with a cron job (see "man cron").
408 For Redhat, a logrotate script has been included.
410 On SuSE Linux systems, you can place a line like "/var/log/junkbuster.* +1024k
411 644 nobody.nogroup" in /etc/logfiles, with the effect that cron.daily will
412 automatically archive, gzip, and empty the log, when it exceeds 1M size.
414 Default: Log to the a file named logfile. Comment out to disable logging.
419 The "jarfile" defines where Junkbuster stores the cookies it intercepts. Note
420 that if you use a "jarfile", it may grow quite large. Default: Don't store
426 If you specify a "trustfile", Junkbuster will only allow access to sites that
427 are named in the trustfile. You can also mark sites as trusted referrers, with
428 the effect that access to untrusted sites will be granted, if a link from a
429 trusted referrer was used. The link target will then be added to the
430 "trustfile". This is a very restrictive feature that typical users most
431 probably want to leave disabled. Default: Disabled, don't use the trust
437 If you use the trust mechanism, it is a good idea to write up some on-line
438 documentation about your blocking policy and to specify the URL(s) here. They
439 will appear on the page that your users receive when they try to access
440 untrusted content. Use multiple times for multiple URLs. Default: Don't display
441 links on the "untrusted" info page.
443 trust-info-url http://www.your-site.com/why_we_block.html
444 trust-info-url http://www.your-site.com/what_we_allow.html
447 -------------------------------------------------------------------------------
449 3.1.2. Other Configuration Options
451 This part of the configuration file contains options that control how
454 "Admin-address" should be set to the email address of the proxy administrator.
455 It is used in many of the proxy-generated pages. Default: fill@me.in.please.
457 #admin-address fill@me.in.please
460 "Proxy-info-url" can be set to a URL that contains more info about this
461 Junkbuster installation, it's configuration and policies. It is used in many of
462 the proxy-generated pages and its use is highly recommended in multi-user
463 installations, since your users will want to know why certain content is
464 blocked or modified. Default: Don't show a link to on-line documentation.
466 proxy-info-url http://www.your-site.com/proxy.html
469 "Listen-address" specifies the address and port where Junkbuster will listen
470 for connections from your Web browser. The default is to listen on the
471 localhost port 8000, and this is suitable for most users. (In your web browser,
472 under proxy configuration, list the proxy server as "localhost" and the port as
475 If you already have another service running on port 8000, or if you want to
476 serve requests from other machines (e.g. on your local network) as well, you
477 will need to override the default. The syntax is "listen-address
478 [<ip-address>]:<port>". If you leave out the IP address, junkbuster will bind
479 to all interfaces (addresses) on your machine and may become reachable from the
480 Internet. In that case, consider using access control lists (acl's) (see
481 "aclfile" above), or a firewall.
483 For example, suppose you are running Junkbuster on a machine which has the
484 address 192.168.0.1 on your local private network (192.168.0.0) and has another
485 outside connection with a different address. You want it to serve requests from
488 listen-address 192.168.0.1:8000
491 If you want it to listen on all addresses (including the outside connection):
496 If you do this, consider using ACLs (see "aclfile" above). Note: you will need
497 to point your browser(s) to the address and port that you have configured here.
498 Default: localhost:8000 (127.0.0.1:8000).
500 The debug option sets the level of debugging information to log in the logfile
501 (and to the console in the Windows version). A debug level of 1 is informative
502 because it will show you each request as it happens. Higher levels of debug are
503 probably only of interest to developers.
505 debug 1 # GPC = show each GET/POST/CONNECT request
506 debug 2 # CONN = show each connection status
507 debug 4 # IO = show I/O status
508 debug 8 # HDR = show header parsing
509 debug 16 # LOG = log all data into the logfile
510 debug 32 # FRC = debug force feature
511 debug 64 # REF = debug regular expression filter
512 debug 128 # = debug fast redirects
513 debug 256 # = debug GIF de-animation
514 debug 512 # CLF = Common Log Format
515 debug 1024 # = debug kill pop-ups
516 debug 4096 # INFO = Startup banner and warnings.
517 debug 8192 # ERROR = Non-fatal errors
520 It is highly recommended that you enable ERROR reporting (debug 8192), at least
521 until the next stable release.
523 The reporting of FATAL errors (i.e. ones which crash JunkBuster) is always on
524 and cannot be disabled.
526 If you want to use CLF (Common Log Format), you should set "debug 512" ONLY, do
527 not enable anything else.
529 Multiple "debug" directives, are OK - they're logical-OR'd together.
531 debug 15 # same as setting the first 4 listed above
538 debug 8192 # Errors - *we highly recommended enabling this*
541 Junkbuster normally uses "multi-threading", a software technique that permits
542 it to handle many different requests simultaneously. In some cases you may wish
543 to disable this -- particularly if you're trying to debug a problem. The
544 "single-threaded" option forces Junkbuster to handle requests sequentially.
545 Default: Multi-threaded mode.
550 "toggle" allows you to temporarily disable all Junkbuster's filtering. Just set
553 The Windows version of Junkbuster puts an icon in the system tray, which also
554 allows you to change this option. If you right-click on that icon (or select
555 the "Options" menu), one choice is "Enable". Clicking on enable toggles
556 Junkbuster on and off. This is useful if you want to temporarily disable
557 Junkbuster, e.g., to access a site that requires cookies which you would
558 otherwise have blocked. This can also be toggled via a web browser at the
559 Junkbuster internal address of http://i.j.b on any platform.
561 "toggle 1" means Junkbuster runs normally, "toggle 0" means that Junkbuster
562 becomes a non-anonymizing non-blocking proxy. Default: 1 (on).
567 For content filtering, i.e. the "+filter" and "+deanimate-gif" actions, it is
568 necessary that Junkbuster buffers the entire document body. This can be
569 potentially dangerous, since a server could just keep sending data indefinitely
570 and wait for your RAM to exhaust. With nasty consequences.
572 The buffer-limit option lets you set the maximum size in Kbytes that each
573 buffer may use. When the documents buffer exceeds this size, it is flushed to
574 the client unfiltered and no further attempt to filter the rest of it is made.
575 Remember that there may multiple threads running, which might require
576 increasing the "buffer-limit" Kbytes each, unless you have enabled
577 "single-threaded" above.
582 To enable the web-based ijb.action file editor set enable-edit-actions to 1, or
583 0 to disable. Note that you must have compiled JunkBuster with support for this
584 feature, otherwise this option has no effect. This internal page can be reached
587 Security note: If this is enabled, anyone who can use the proxy can edit the
588 actions file, and their changes will affect all users. For shared proxies, you
589 probably want to disable this. Default: enabled.
591 enable-edit-actions 1
594 Allow JunkBuster to be toggled on and off remotely, using your web browser. Set
595 "enable-remote-toggle"to 1 to enable, and 0 to disable. Note that you must have
596 compiled JunkBuster with support for this feature, otherwise this option has no
599 Security note: If this is enabled, anyone who can use the proxy can toggle it
600 on or off (see http://i.j.b), and their changes will affect all users. For
601 shared proxies, you probably want to disable this. Default: enabled.
603 enable-remote-toggle 1
606 -------------------------------------------------------------------------------
608 3.1.3. Access Control List (ACL)
610 Access controls are included at the request of some ISPs and systems
611 administrators, and are not usually needed by individual users. Please note the
612 warnings in the FAQ that this proxy is not intended to be a substitute for a
613 firewall or to encourage anyone to defer addressing basic security weaknesses.
615 If no access settings are specified, the proxy talks to anyone that connects.
616 If any access settings file are specified, then the proxy talks only to IP
617 addresses permitted somewhere in this file and not denied later in this file.
619 Summary -- if using an ACL:
621 Client must have permission to receive service.
623 LAST match in ACL wins.
625 Default behavior is to deny service.
627 The syntax for an entry in the Access Control List is:
629 ACTION SRC_ADDR[/SRC_MASKLEN] [ DST_ADDR[/DST_MASKLEN] ]
632 Where the individual fields are:
634 ACTION = "permit-access" or "deny-access"
636 SRC_ADDR = client hostname or dotted IP address
637 SRC_MASKLEN = number of bits in the subnet mask for the source
639 DST_ADDR = server or forwarder hostname or dotted IP address
640 DST_MASKLEN = number of bits in the subnet mask for the target
643 The field separator (FS) is whitespace (space or tab).
645 IMPORTANT NOTE: If the junkbuster is using a forwarder (see below) or a gateway
646 for a particular destination URL, the DST_ADDR that is examined is the address
647 of the forwarder or the gateway and NOT the address of the ultimate target.
648 This is necessary because it may be impossible for the local Junkbuster to
649 determine the address of the ultimate target (that's often what gateways are
652 Here are a few examples to show how the ACL features work:
654 "localhost" is OK -- no DST_ADDR implies that ALL destination addresses are OK:
656 permit-access localhost
659 A silly example to illustrate permitting any host on the class-C subnet with
660 Junkbuster to go anywhere:
662 permit-access www.junkbusters.com/24
665 Except deny one particular IP address from using it at all:
667 deny-access ident.junkbusters.com
670 You can also specify an explicit network address and subnet mask. Explicit
671 addresses do not have to be resolved to be used.
673 permit-access 207.153.200.0/24
676 A subnet mask of 0 matches anything, so the next line permits everyone.
678 permit-access 0.0.0.0/0
681 Note, you cannot say:
686 to allow all *.org domains. Every IP address listed must resolve fully.
688 An ISP may want to provide a Junkbuster that is accessible by "the world" and
689 yet restrict use of some of their private content to hosts on its internal
690 network (i.e. its own subscribers). Say, for instance the ISP owns the Class-B
691 IP address block 123.124.0.0 (a 16 bit netmask). This is how they could do it:
693 permit-access 0.0.0.0/0 0.0.0.0/0 # other clients can go anywhere
694 # with the following exceptions:
696 deny-access 0.0.0.0/0 123.124.0.0/16 # block all external requests for
697 # sites on the ISP's network
699 permit 0.0.0.0/0 www.my_isp.com # except for the ISP's main
702 permit 123.124.0.0/16 0.0.0.0/0 # the ISP's clients can go
706 Note that if some hostnames are listed with multiple IP addresses, the primary
707 value returned by DNS (via gethostbyname()) is used. Default: Anyone can access
710 -------------------------------------------------------------------------------
714 This feature allows chaining of HTTP requests via multiple proxies. It can be
715 used to better protect privacy and confidentiality when accessing specific
716 domains by routing requests to those domains to a special purpose filtering
717 proxy such as lpwa.com. Or to use a caching proxy to speed up browsing.
719 It can also be used in an environment with multiple networks to route requests
720 via multiple gateways allowing transparent access to multiple networks without
721 having to modify browser configurations.
723 Also specified here are SOCKS proxies. Junkbuster SOCKS 4 and SOCKS 4A. The
724 difference is that SOCKS 4A will resolve the target hostname using DNS on the
725 SOCKS server, not our local DNS client.
727 The syntax of each line is:
729 forward target_domain[:port] http_proxy_host[:port]
730 forward-socks4 target_domain[:port] socks_proxy_host[:port] http_proxy_host[:
732 forward-socks4a target_domain[:port] socks_proxy_host[:port] http_proxy_host[:
736 If http_proxy_host is ".", then requests are not forwarded to a HTTP proxy but
737 are made directly to the web servers.
739 Lines are checked in sequence, and the last match wins.
741 There is an implicit line equivalent to the following, which specifies that
742 anything not finding a match on the list is to go out without forwarding or
743 gateway protocol, like so:
745 forward .* . # implicit
748 In the following common configuration, everything goes to Lucent's LPWA, except
749 SSL on port 443 (which it doesn't handle):
751 forward .* lpwa.com:8000
755 See the FAQ for instructions on how to automate the login procedure for LPWA.
756 Some users have reported difficulties related to LPWA's use of "." as the last
757 element of the domain, and have said that this can be fixed with this:
759 forward lpwa. lpwa.com:8000
762 (NOTE: the syntax for specifying target_domain has changed since the previous
763 paragraph was written -- it will not work now. More information is welcome.)
765 In this fictitious example, everything goes via an ISP's caching proxy, except
766 requests to that ISP:
768 forward .* caching.myisp.net:8000
772 For the @home network, we're told the forwarding configuration is this:
774 forward .* proxy:8080
777 Also, we're told they insist on getting cookies and JavaScript, so you should
778 add home.com to the cookie file. We consider JavaScript a security risk. Java
781 In this example direct connections are made to all "internal" domains, but
782 everything else goes through Lucent's LPWA by way of the company's SOCKS
783 gateway to the Internet.
785 forward-socks4 .* lpwa.com:8000 firewall.my_company.com:1080
786 forward my_company.com .
789 This is how you could set up a site that always uses SOCKS but no forwarders:
791 forward-socks4a .* . firewall.my_company.com:1080
794 An advanced example for network administrators:
796 If you have links to multiple ISPs that provide various special content to
797 their subscribers, you can configure forwarding to pass requests to the
798 specific host that's connected to that ISP so that everybody can see all of the
799 content on all of the ISPs.
801 This is a bit tricky, but here's an example:
803 host-a has a PPP connection to isp-a.com. And host-b has a PPP connection to
804 isp-b.com. host-a can run a Junkbuster proxy with forwarding like this:
807 forward isp-b.com host-b:8000
810 host-b can run a Junkbuster proxy with forwarding like this:
813 forward isp-a.com host-a:8000
816 Now, anyone on the Internet (including users on host-a and host-b) can set
817 their browser's proxy to either host-a or host-b and be able to browse the
818 content on isp-a or isp-b.
820 Here's another practical example, for University of Kent at Canterbury students
821 with a network connection in their room, who need to use the University's Squid
824 forward *. ssbcache.ukc.ac.uk:3128 # Use the proxy, except for:
825 forward .ukc.ac.uk . # Anything on the same domain as us
826 forward * . # Host with no domain specified
827 forward 129.12.*.* . # A dotted IP on our /16 network.
828 forward 127.*.*.* . # Loopback address
829 forward localhost.localdomain . # Loopback address
830 forward www.ukc.mirror.ac.uk . # Specific host
833 If you intend to chain Junkbuster and squid locally, then chain as browser ->
834 squid -> junkbuster is the recommended way.
836 Your squid configuration could then look like this:
838 # Define junkbuster as parent cache
840 cache_peer 127.0.0.1 parent 8000 0 no-query
842 # Define ACL for protocol FTP
845 # Do not forward ACL FTP to junkbuster
846 always_direct allow FTP
848 # Do not forward ACL CONNECT (https) to junkbuster
849 always_direct allow CONNECT
851 # Forward the rest to junkbuster
852 never_direct allow all
855 -------------------------------------------------------------------------------
857 3.1.5. Windows GUI Options
859 Junkbuster has a number of options specific to the Windows GUI interface:
861 If "activity-animation" is set to 1, the Junkbuster icon will animate when
862 "Junkbuster" is active. To turn off, set to 0.
867 If "log-messages" is set to 1, Junkbuster will log messages to the console
873 If "log-buffer-size" is set to 1, the size of the log buffer, i.e. the amount
874 of memory used for the log messages displayed in the console window, will be
875 limited to "log-max-lines" (see below).
877 Warning: Setting this to 0 will result in the buffer to grow infinitely and eat
883 log-max-lines is the maximum number of lines held in the log buffer. See above.
888 If "log-highlight-messages" is set to 1, Junkbuster will highlight portions of
889 the log messages with a bold-faced font:
891 log-highlight-messages 1
894 The font used in the console window:
896 log-font-name Comic Sans MS
899 Font size used in the console window:
904 "show-on-task-bar" controls whether or not Junkbuster will appear as a button
905 on the Task bar when minimized:
910 If "close-button-minimizes" is set to 1, the Windows close button will minimize
911 Junkbuster instead of closing the program (close with the exit option on the
914 close-button-minimizes 1
917 The "hide-console" option is specific to the MS-Win console version of
918 JunkBuster. If this option is used, Junkbuster will disconnect from and hide
924 -------------------------------------------------------------------------------
926 3.2. The Actions File
928 The "ijb.action" file (formerly actionsfile) is used to define what actions
929 Junkbuster takes, and thus determines how images, cookies and various other
930 aspects of HTTP content and transactions are handled. Images can be anything
931 you want, including ads, banners, or just some obnoxious image that you would
932 rather not see. Cookies can be accepted or rejected, or accepted only during
933 the current browser session (i.e. not written to disk). Changes to ijb.action
934 should be immediately visible to Junkbuster without the need to restart.
936 To determine which actions apply to a request, the URL of the request is
937 compared to all patterns in this file. Every time it matches, the list of
938 applicable actions for the URL is incrementally updated. You can trace this
939 process by visiting http://i.j.b/show-url-info.
941 The actions file can be edited with a browser by loading http://i.j.b/, and
942 then select "Edit Actions".
944 There are four types of lines in this file: comments (begin with a "#"
945 character), actions, aliases and patterns, all of which are explained below, as
946 well as the configuration file syntax that Junkbuster understands.
948 -------------------------------------------------------------------------------
950 3.2.1. URL Domain and Path Syntax
952 Generally, a pattern has the form <domain>/<path>, where both the <domain> and
953 <path> part are optional. If you only specify a domain part, the "/" can be
956 www.example.com - is a domain only pattern and will match any request to
959 www.example.com/ - means exactly the same.
961 www.example.com/index.html - matches only the single document "/index.html" on
964 /index.html - matches the document "/index.html", regardless of the domain.
966 index.html - matches nothing, since it would be interpreted as a domain name
967 and there is no top-level domain called ".html".
969 The matching of the domain part offers some flexible options: if the domain
970 starts or ends with a dot, it becomes unanchored at that end. For example:
972 .example.com - matches any domain that ENDS in ".example.com".
974 www. - matches any domain that STARTS with "www".
976 Additionally, there are wild-cards that you can use in the domain names
977 themselves. They work pretty similar to shell wild-cards: "*" stands for zero
978 or more arbitrary characters, "?" stands for any single character. And you can
979 define character classes in square brackets and they can be freely mixed:
981 ad*.example.com - matches "adserver.example.com", "ads.example.com", etc but
982 not "sfads.example.com".
984 *ad*.example.com - matches all of the above, and then some.
986 .?pix.com - matches "www.ipix.com", "pictures.epix.com", "a.b.c.d.e.upix.com",
989 www[1-9a-ez].example.com - matches "www1.example.com", "www4.example.com",
990 "wwwd.example.com", "wwwz.example.com", etc., but not "wwww.example.com".
992 If Junkbuster was compiled with "pcre" support (default), Perl compatible
993 regular expressions can be used. See the pcre/docs/ directory or "man perlre"
994 (also available on http://www.perldoc.com/perl5.6/pod/perlre.html) for details.
995 A brief discussion of regular expressions is in the Appendix. For instance:
997 /.*/advert[0-9]+\.jpe?g - would match a URL from any domain, with any path that
998 includes "advert" followed immediately by one or more digits, then a "." and
999 ending in either "jpeg" or "jpg". So we match "example.com/ads/advert2.jpg",
1000 and "www.example.com/ads/banners/advert39.jpeg", but not "www.example.com/ads/
1001 banners/advert39.gif" (no gifs in the example pattern).
1003 Please note that matching in the path is case INSENSITIVE by default, but you
1004 can switch to case sensitive at any point in the pattern by using the "(?-i)"
1007 www.example.com/(?-i)PaTtErN.* - will match only documents whose path starts
1008 with "PaTtErN" in exactly this capitalization.
1010 -------------------------------------------------------------------------------
1014 Actions are enabled if preceded with a "+", and disabled if preceded with a
1015 "-". Actions are invoked by enclosing the action name in curly braces (e.g.
1016 {+some_action}), followed by a list of URLs to which the action applies. There
1017 are three classes of actions:
1019 * Boolean (e.g. "+/-block"):
1021 {+name} # enable this action
1022 {-name} # disable this action
1025 * parameterized (e.g. "+/-hide-user-agent"):
1027 {+name{param}} # enable action and set parameter to "param"
1028 {-name} # disable action
1031 * Multi-value (e.g. "{+/-add-header{Name: value}}", "{+/-wafer{name=value}}
1034 {+name{param}} # enable action and add parameter "param"
1035 {-name{param}} # remove the parameter "param"
1036 {-name} # disable this action totally
1039 If nothing is specified in this file, no "actions" are taken. So in this case
1040 JunkBuster would just be a normal, non-blocking, non-anonymizing proxy. You
1041 must specifically enable the privacy and blocking features you need (although
1042 the provided default ijb.action file will give a good starting point).
1044 Later defined actions always over-ride earlier ones. For multi-valued actions,
1045 the actions are applied in the order they are specified.
1047 The list of valid Junkbuster "actions" are:
1049 * Add the specified HTTP header, which is not checked for validity. You may
1050 specify this many times to specify many different headers:
1052 +add-header{Name: value}
1055 * Block this URL totally.
1060 * De-animate all animated GIF images, i.e. reduce them to their last frame.
1061 This will also shrink the images considerably (in bytes, not pixels!). If
1062 the option "first" is given, the first frame of the animation is used as
1063 the replacement. If "last" is given, the last frame of the animation is
1064 used instead, which probably makes more sense for most banner animations,
1065 but also has the risk of not showing the entire last frame (if it is only a
1066 delta to an earlier frame).
1068 +deanimate-gifs{last}
1069 +deanimate-gifs{first}
1072 * "+downgrade" will downgrade HTTP/1.1 client requests to HTTP/1.0 and
1073 downgrade the responses as well. Use this action for servers that use HTTP/
1074 1.1 protocol features that Junkbuster doesn't handle well yet. HTTP/1.1 is
1075 only partially implemented. Default is not to downgrade requests.
1080 * Many sites, like yahoo.com, don't just link to other sites. Instead, they
1081 will link to some script on their own server, giving the destination as a
1082 parameter, which will then redirect you to the final target. URLs resulting
1083 from this scheme typically look like: http://some.place/some_script?http://
1086 Sometimes, there are even multiple consecutive redirects encoded in the
1087 URL. These redirections via scripts make your web browsing more traceable,
1088 since the server from which you follow such a link can see where you go to.
1089 Apart from that, valuable bandwidth and time is wasted, while your browser
1090 ask the server for one redirect after the other. Plus, it feeds the
1093 The "+fast-redirects" option enables interception of these requests by
1094 Junkbuster, who will cut off all but the last valid URL in the request and
1095 send a local redirect back to your browser without contacting the remote
1101 * Filter the website through the re_filterfile:
1106 * Block any existing X-Forwarded-for header, and do not add a new one:
1111 * If the browser sends a "From:" header containing your e-mail address, this
1112 either completely removes the header ("block"), or changes it to the
1113 specified e-mail address.
1116 +hide-from{spam@sittingduck.xqq}
1119 * Don't send the "Referer:" (sic) header to the web site. You can block it,
1120 forge a URL to the same server as the request (which is preferred because
1121 some sites will not send images otherwise) or set it to a constant string
1124 +hide-referer{block}
1125 +hide-referer{forge}
1126 +hide-referer{http://nowhere.com}
1129 * Alternative spelling of "+hide-referer". It has the same parameters, and
1130 can be freely mixed with, "+hide-referer". ("referrer" is the correct
1131 English spelling, however the HTTP specification has a bug - it requires it
1132 to be spelled "referer".)
1137 * Change the "User-Agent:" header so web servers can't tell your browser
1138 type. Warning! This breaks many web sites. Specify the user-agent value you
1139 want. Example, pretend to be using Netscape on Linux:
1141 +hide-user-agent{Mozilla (X11; I; Linux 2.0.32 i586)}
1144 * Treat this URL as an image. This only matters if it's also "+block"ed, in
1145 which case a "blocked" image can be sent rather than a HTML page. See
1146 "+image-blocker{}" below for the control over what is actually sent.
1151 * Decides what to do with URLs that end up tagged with "{+block +image}".
1152 There are 4 options. "-image-blocker" will send a HTML "blocked" page,
1153 usually resulting in a "broken image" icon. "+image-blocker{logo}" will
1154 send a "JunkBuster" image. "+image-blocker{blank}" will send a 1x1
1155 transparent GIF image. And finally, "+image-blocker{http://xyz.com}" will
1156 send a HTTP temporary redirect to the specified image. This has the
1157 advantage of the icon being being cached by the browser, which will speed
1160 +image-blocker{logo}
1161 +image-blocker{blank}
1162 +image-blocker{http://i.j.b/send-banner}
1165 * By default (i.e. in the absence of a "+limit-connect" action), Junkbuster
1166 will only allow CONNECT requests to port 443, which is the standard port
1167 for https as a precaution.
1169 The CONNECT methods exists in HTTP to allow access to secure websites
1170 (https:// URLs) through proxies. It works very simply: the proxy connects
1171 to the server on the specified port, and then short-circuits its
1172 connections to the client and to the remote proxy. This can be a big
1173 security hole, since CONNECT-enabled proxies can be abused as TCP relays
1176 If you want to allow CONNECT for more ports than this, or want to forbid
1177 CONNECT altogether, you can specify a comma separated list of ports and
1178 port ranges (the latter using dashes, with the minimum defaulting to 0 and
1181 +limit-connect{443} # This is the default and need no be specified.
1182 +limit-connect{80,443} # Ports 80 and 443 are OK.
1183 +limit-connect{-3, 7, 20-100, 500-} # Port less than 3, 7, 20 to 100
1184 #and above 500 are OK.
1187 * "+no-compression" prevents the website from compressing the data. Some
1188 websites do this, which can be a problem for Junkbuster, since "+filter",
1189 "+no-popup" and "+gif-deanimate" will not work on compressed data. This
1190 will slow down connections to those websites, though. Default is
1191 "nocompression" is turned on.
1196 * If the website sets cookies, "no-cookies-keep" will make sure they are
1197 erased when you exit and restart your web browser. This makes profiling
1198 cookies useless, but won't break sites which require cookies so that you
1199 can log in for transactions. Default: on.
1204 * Prevent the website from reading cookies:
1209 * Prevent the website from setting cookies:
1214 * Filter the website through a built-in filter to disable those obnoxious
1215 JavaScript pop-up windows via window.open(), etc. The two alternative
1216 spellings are equivalent.
1222 * This action only applies if you are using a jarfile for saving cookies. It
1223 sends a cookie to every site stating that you do not accept any copyright
1224 on cookies sent to you, and asking them not to track you. Of course, this
1225 is a (relatively) unique header they could use to track you.
1230 * This allows you to add an arbitrary cookie. It can be specified multiple
1231 times in order to add as many cookies as you like.
1236 The meaning of any of the above is reversed by preceding the action with a "-",
1237 in place of the "+".
1241 Turn off cookies by default, then allow a few through for specified sites:
1243 # Turn off all persistent cookies
1244 { +no-cookies-read }
1246 # Allow cookies for this browser session ONLY
1247 { +no-cookies-keep }
1249 # Exceptions to the above, sites that benefit from persistent cookies
1250 { -no-cookies-read }
1252 { -no-cookies-keep }
1259 # Alternative way of saying the same thing
1260 {-no-cookies-set -no-cookies-read -no-cookies-keep}
1265 Now turn off "fast redirects", and then we allow two exceptions:
1270 # Reverse it for these two sites, which don't work right without it.
1272 www.ukc.ac.uk/cgi-bin/wac\.cgi\?
1276 Turn on page filtering, with one exception for sourceforge:
1278 # Run everything through the default filter file (re_filterfile):
1281 # But please don't re_filter code from sourceforge!
1283 .cvs.sourceforge.net
1286 Now some URLs that we want "blocked", ie we won't see them. Many of these use
1287 regular expressions that will expand to match multiple URLs:
1291 /.*/(.*[-_.])?ads?[0-9]?(/|[-_.].*|\.(gif|jpe?g))
1292 /.*/(.*[-_.])?count(er)?(\.cgi|\.dll|\.exe|[?/])
1293 /.*/(ng)?adclient\.cgi
1294 /.*/(plain|live|rotate)[-_.]?ads?/
1295 /.*/(sponsor)s?[0-9]?/
1296 /.*/_?(plain|live)?ads?(-banners)?/
1298 /.*/ad(sdna_image|gifs?)/
1299 /.*/ad(server|stream|juggler)\.(cgi|pl|dll|exe)
1303 /.*/adv((er)?ts?|ertis(ing|ements?))?/
1307 /.*/cgi-bin/centralad/getimage
1308 /.*/images/addver\.gif
1309 /.*/images/marketing/.*\.(gif|jpe?g)
1313 /.*/sponsors?[0-9]?/
1314 /.*/advert[0-9]+\.jpg
1321 /graphics/defaultAd/
1323 /image\.ng/transactionID
1324 /images/.*/.*_anim\.gif # alvin brattli
1325 /ip_img/.*\.(gif|jpe?g)
1329 /cgi-bin/nph-adclick.exe/
1330 /.*/Image/BannerAdvertising/
1332 /.*/adlib/server\.cgi
1336 -------------------------------------------------------------------------------
1340 Custom "actions", known to Junkbuster as "aliases", can be defined by combining
1341 other "actions". These can in turn be invoked just like the built-in "actions".
1342 Currently, an alias can contain any character except space, tab, "=", "{" or "}
1343 ". But please use only "a"- "z", "0"-"9", "+", and "-". Alias names are not
1344 case sensitive, and must be defined before anything else in the ijb.actionfile
1345 ! And there can only be one set of "aliases" defined.
1347 Now let's define a few aliases:
1349 # Useful customer aliases we can use later. These must come first!
1351 +no-cookies = +no-cookies-set +no-cookies-read
1352 -no-cookies = -no-cookies-set -no-cookies-read
1354 -block -no-cookies -filter -fast-redirects -hide-referer -no-popups
1355 shop = -no-cookies -filter -fast-redirects
1356 +imageblock = +block +image
1358 #For people who don't like to type too much: ;-)
1361 c2 = -no-cookies-set +no-cookies-read
1362 c3 = +no-cookies-set -no-cookies-read
1363 #... etc. Customize to your heart's content.
1366 Some examples using our "shop" and "fragile" aliases from above:
1368 # These sites are very complex and require
1369 # minimal interference.
1371 .office.microsoft.com
1372 .windowsupdate.microsoft.com
1375 # Shopping sites - still want to block ads.
1378 .worldpay.com # for quietpc.com
1382 # These shops require pop-ups
1388 -------------------------------------------------------------------------------
1390 3.3. The Filter File
1392 The filter file defines what filtering of web pages Junkbuster does. The
1393 default filter file is re_filterfile, located in the config directory. In this
1394 file, any document content, whether viewable text or embedded non-visible
1395 content, can be changed.
1397 This file uses regular expressions to alter or remove any string in the target
1398 page. Some examples from the included default re_filterfile:
1400 Stop web pages from displaying annoying messages in the status bar by deleting
1403 # The status bar is for displaying link targets, not pointless buzzwords.
1404 # Again, check it out on http://www.airport-cgn.de/.
1405 s/status='.*?';*//ig
1408 Just for kicks, replace any occurrence of "Microsoft" with "MicroSuck":
1410 s/microsoft(?!.com)/MicroSuck/ig
1413 Kill those auto-refresh tags:
1415 # Kill refresh tags. I like to refresh myself. Manually.
1416 # check it out on http://www.airport-cgn.de/ and go to the arrivals page.
1418 s/<meta[^>]*http-equiv[^>]*refresh.*URL=([^>]*?)"?>/<link rev="x-refresh" href
1420 s/<meta[^>]*http-equiv="?page-enter"?[^>]*content=[^>]*>/<!
1421 --no page enter for me-->/i
1424 -------------------------------------------------------------------------------
1428 When Junkbuster displays one of its internal pages, such as a 404 Not Found
1429 error page, it uses the appropriate template. On Linux, BSD, and Unix, these
1430 are locate in /etc/junkbuster/templates by default. These may be customized, if
1433 -------------------------------------------------------------------------------
1435 4. Quickstart to Using Junkbuster
1437 Install package, then run and enjoy! JunkBuster accepts only one command line
1438 option -- the configuration file to be used. Example Unix startup command:
1441 # /usr/sbin/junkbuster /etc/junkbuster/config
1445 An init script is provided for SuSE and Redhat.
1447 For for SuSE: /etc/rc.d/junkbuster start
1449 For RedHat: /etc/rc.d/init.d/junkbuster start
1451 If no configuration file is specified on the command line, Junkbuster will look
1452 for a file named config in the current directory. Except on Amiga where it will
1453 look for AmiTCP:db/junkbuster/config and Win32 where it will try config.txt. If
1454 no file is specified on the command line and no default configuration file can
1455 be found, Junkbuster will fail to start.
1457 Be sure your browser is set to use the proxy which is by default at localhost,
1458 port 8000. With Netscape (and Mozilla), this can be set under Edit ->
1459 Preferences -> Advanced -> Proxies -> HTTP Proxy. For Internet Explorer: Tools
1460 > Internet Properties -> Connections -> LAN Setting. Then, check "Use Proxy"
1461 and fill in the appropriate info (Address: localhost, Port: 8000). Include if
1462 HTTPS proxy support too.
1464 The included default configuration files should give a reasonable starting
1465 point, though may be somewhat aggressive in blocking junk. You will probably
1466 want to keep an eye out for sites that require persistent cookies, and add
1467 these to ijb.action as needed. By default, most of these will be accepted only
1468 during the current browser session, until you add them to the configuration. If
1469 you want the browser to handle this instead, you will need to edit ijb.action
1470 and disable this feature. If you use more than one browser, it would make more
1471 sense to let Junkbuster handle this. In which case, the browser(s) should be
1472 set to accept all cookies.
1474 If a particular site shows problems loading properly, try adding it to the
1475 {fragile} section of ijb.action. This will turn off most actions for this site.
1477 HTTP/1.1 support is not fully implemented. If browsers that support HTTP/1.1
1478 (like Mozilla or recent versions of I.E.) experience problems, you might try to
1479 force HTTP/1.0 compatibility. For Mozilla, look under Edit -> Preferences ->
1480 Debug -> Networking. Or set the "+downgrade" config option in ijb.action.
1482 After running Junkbuster for a while, you can start to fine tune the
1483 configuration to suit your personal, or site, preferences and requirements.
1484 There are many, many aspects that can be customized. "Actions" (as specified in
1485 ijb.action) can be adjusted by pointing your browser to http://i.j.b/, and then
1486 follow the link to "edit the actions list". (This is an internal page and does
1487 not require Internet access.)
1489 In fact, various aspects of Junkbuster configuration can be viewed from this
1490 page, including current configuration parameters, source code version numbers,
1491 the browser's request headers, and "actions" that apply to a given URL. In
1492 addition to the ijb.action file editor mentioned above, Junkbuster can also be
1493 turned "on" and "off" from this page.
1495 If you encounter problems, please verify it is a Junkbuster bug, by disabling
1496 Junkbuster, and then trying the same page. Also, try another browser if
1497 possible to eliminate browser or site problems. Before reporting it as a bug,
1498 see if there is not a configuration option that is enabled that is causing the
1499 page not to load. You can then add an exception for that page or site. If a
1500 bug, please report it to the developers (see below).
1502 -------------------------------------------------------------------------------
1504 5. Contact the Developers
1506 Feature requests and other questions should be posted to the Feature request
1507 page at SourceForge. There is also an archive there.
1509 Anyone interested in actively participating in development and related
1510 discussions can join the appropriate mailing list here. Archives are available
1513 Please report bugs, using the form at Sourceforge. Please try to verify that it
1514 is a Junkbuster bug, and not a browser or site bug first. Also, check to make
1515 sure this is not already a known bug.
1517 -------------------------------------------------------------------------------
1519 6. Copyright and History
1523 Internet Junkbuster is free software; you can redistribute it and/or modify it
1524 under the terms of the GNU General Public License as published by the Free
1525 Software Foundation; either version 2 of the License, or (at your option) any
1528 This program is distributed in the hope that it will be useful, but WITHOUT ANY
1529 WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A
1530 PARTICULAR PURPOSE. See the GNU General Public License for more details, which
1531 is available from the Free Software Foundation, Inc, 59 Temple Place - Suite
1532 330, Boston, MA 02111-1307, USA.
1534 -------------------------------------------------------------------------------
1538 Junkbuster was originally written by Anonymous Coders and Junkbuster's
1539 Corporation, and was released as free open-source software under the GNU GPL.
1540 Stefan Waldherr made many improvements, and started the SourceForge project to
1541 rekindle development. The last stable release was v2.0.2, which has now grown
1544 -------------------------------------------------------------------------------
1548 http://sourceforge.net/projects/ijbswa
1550 http://ijbswa.sourceforge.net/
1554 http://www.junkbusters.com/ht/en/cookies.html
1556 http://www.waldherr.org/junkbuster/
1558 http://privacy.net/analyze/
1560 http://www.squid-cache.org/
1564 -------------------------------------------------------------------------------
1568 8.1. Regular Expressions
1570 Junkbuster can use "regular expressions" in various config files. Assuming
1571 support for "pcre" (Perl Compatible Regular Expressions) is compiled in, which
1572 is the default. Such configuration directives do not require regular
1573 expressions, but they can be used to increase flexibility by matching a pattern
1574 with wild-cards against URLs.
1576 If you are reading this, you probably don't understand what "regular
1577 expressions" are, or what they can do. So this will be a very brief
1578 introduction only. A full explanation would require a book ;-)
1580 "Regular expressions" is a way of matching one character expression against
1581 another to see if it matches or not. One of the "expressions" is a literal
1582 string of readable characters (letter, numbers, etc), and the other is a
1583 complex string of literal characters combined with wild-cards, and other
1584 special characters, called meta-characters. The "meta-characters" have special
1585 meanings and are used to build the complex pattern to be matched against. Perl
1586 Compatible Regular Expressions is an enhanced form of the regular expression
1587 language with backward compatibility.
1589 To make a simple analogy, we do something similar when we use wild-card
1590 characters when listing files with the dir command in DOS. *.* matches all
1591 filenames. The "special" character here is the asterisk which matches any and
1592 all characters. We can be more specific and use ? to match just individual
1593 characters. So "dir file?.text" would match "file1.txt", "file2.txt", etc. We
1594 are pattern matching, using a similar technique to "regular expressions"!
1596 Regular expressions do essentially the same thing, but are much, much more
1597 powerful. There are many more "special characters" and ways of building complex
1598 patterns however. Let's look at a few of the common ones, and then some
1601 . - Matches any single character, e.g. "a", "A", "4", ":", or "@".
1603 ? - The preceding character or expression is matched ZERO or ONE times. Either/
1606 + - The preceding character or expression is matched ONE or MORE times.
1608 * - The preceding character or expression is matched ZERO or MORE times.
1610 \ - The "escape" character denotes that the following character should be taken
1611 literally. This is used where one of the special characters (e.g. ".") needs to
1612 be taken literally and not as a special meta-character.
1614 [] - Characters enclosed in brackets will be matched if any of the enclosed
1615 characters are encountered.
1617 () - parentheses are used to group a sub-expression, or multiple
1620 | - The "bar" character works like an "or" conditional statement. A match is
1621 successful if the sub-expression on either side of "|" matches.
1623 s/string1/string2/g - This is used to rewrite strings of text. "string1" is
1624 replaced by "string2" in this example.
1626 These are just some of the ones you are likely to use when matching URLs with
1627 Junkbuster, and is a long way from a definitive list. This is enough to get us
1628 started with a few simple examples which may be more illuminating:
1630 /.*/banners/.* - A simple example that uses the common combination of "." and "
1631 *" to denote any character, zero or more times. In other words, any string at
1632 all. So we start with a literal forward slash, then our regular expression
1633 pattern (".*") another literal forward slash, the string "banners", another
1634 forward slash, and lastly another ".*". We are building a directory path here.
1635 This will match any file with the path that has a directory named "banners" in
1636 it. The ".*" matches any characters, and this could conceivably be more forward
1637 slashes, so it might expand into a much longer looking path. For example, this
1638 could match: "/eye/hate/spammers/banners/annoy_me_please.gif", or just "/
1639 banners/annoying.html", or almost an infinite number of other possible
1640 combinations, just so it has "banners" in the path somewhere.
1642 A now something a little more complex:
1644 /.*/adv((er)?ts?|ertis(ing|ements?))?/ - We have several literal forward
1645 slashes again ("/"), so we are building another expression that is a file path
1646 statement. We have another ".*", so we are matching against any conceivable
1647 sub-path, just so it matches our expression. The only true literal that must
1648 match our pattern is adv, together with the forward slashes. What comes after
1649 the "adv" string is the interesting part.
1651 Remember the "?" means the preceding expression (either a literal character or
1652 anything grouped with "(...)" in this case) can exist or not, since this means
1653 either zero or one match. So "((er)?ts?|ertis(ing|ements?))" is optional, as
1654 are the individual sub-expressions: "(er)", "(ing|ements?)", and the "s". The "
1655 |" means "or". We have two of those. For instance, "(ing|ements?)", can expand
1656 to match either "ing" OR "ements?". What is being done here, is an attempt at
1657 matching as many variations of "advertisement", and similar, as possible. So
1658 this would expand to match just "adv", or "advert", or "adverts", or
1659 "advertising", or "advertisement", or "advertisements". You get the idea. But
1660 it would not match "advertizements" (with a "z"). We could fix that by changing
1661 our regular expression to: "/.*/adv((er)?ts?|erti(s|z)(ing|ements?))?/", which
1662 would then match either spelling.
1664 /.*/advert[0-9]+\.(gif|jpe?g) - Again another path statement with forward
1665 slashes. Anything in the square brackets "[]" can be matched. This is using
1666 "0-9" as a shorthand expression to mean any digit one through nine. It is the
1667 same as saying "0123456789". So any digit matches. The "+" means one or more of
1668 the preceding expression must be included. The preceding expression here is
1669 what is in the square brackets -- in this case, any digit one through nine.
1670 Then, at the end, we have a grouping: "(gif|jpe?g)". This includes a "|", so
1671 this needs to match the expression on either side of that bar character also. A
1672 simple "gif" on one side, and the other side will in turn match either "jpeg"
1673 or "jpg", since the "?" means the letter "e" is optional and can be matched
1674 once or not at all. So we are building an expression here to match image GIF or
1675 JPEG type image file. It must include the literal string "advert", then one or
1676 more digits, and a "." (which is now a literal, and not a special character,
1677 since it is escaped with "\"), and lastly either "gif", or "jpeg", or "jpg".
1678 Some possible matches would include: "//advert1.jpg", "/nasty/ads/
1679 advert1234.gif", "/banners/from/hell/advert99.jpg". It would not match
1680 "advert1.gif" (no leading slash), or "/adverts232.jpg" (the expression does not
1681 include an "s"), or "/advert1.jsp" ("jsp" is not in the expression anywhere).
1683 s/microsoft(?!.com)/MicroSuck/i - This is a substitution. "MicroSuck" will
1684 replace any occurrence of "microsoft". The "i" at the end of the expression
1685 means ignore case. The "(?!.com)" means the match should fail if "microsoft" is
1686 followed by ".com". In other words, this acts like a "NOT" modifier. In case
1687 this is a hyperlink, we don't want to break it ;-).
1689 We are barely scratching the surface of regular expressions here so that you
1690 can understand the default Junkbuster configuration files, and maybe use this
1691 knowledge to customize your own installation. There is much, much more that can
1692 be done with regular expressions. Now that you know enough to get started, you
1693 can learn more on your own :/
1695 More reading on Perl Compatible Regular expressions: http://www.perldoc.com/
1696 perl5.6/pod/perlre.html