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   rblcheck Manual
   Copyright (C) 2001 Edward S. Marshall

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<!-- We call the book "index" to force db2html to produce an index.html. -->
<Book id="index">

<BookInfo>
 <Title>rblcheck</Title>
 <SubTitle>A command-line interface to RBL-style listings</SubTitle>
 <AuthorGroup>
  <Author>
   <FirstName>Edward</FirstName>
   <OtherName role="mi">S.</OtherName>
   <Surname>Marshall</Surname>
  </Author>
 </AuthorGroup>
 <Copyright>
  <Year>2001</Year>
  <Holder>Edward S. Marshall</Holder>
 </Copyright>
 <LegalNotice id="copyright">
  <Para>
   Permission is granted to copy, distribute and/or modify this document
   under the terms of the GNU Free Documentation License, Version 1.1
   or any later version published by the Free Software Foundation; with
   no Invariant Sections, no Front-Cover Texts, and no Back-Cover Texts.
   A copy of the license is included in <XRef linkend="fdl">.
  </Para>
 </LegalNotice>
</BookInfo>

<Part id="main">
<Title>rblcheck Manual</Title>

<Chapter id="about">
<Title>About rblcheck</Title>
<Para>
rblcheck is a very basic interface to
<ULink url="http://mail-abuse.org/rbl/">RBL</ULink>-style
DNS listings such as those operated by the
<ULink url="http://mail-abuse.org/">MAPS</ULink> and
<ULink url="http://www.orbs.org/">ORBS</ULink> projects.
</Para>

<Para>
The general idea behind RBL-style listings is rapid lookup of IP
addresses using DNS (for example, for blacklisting IP addresses because
of abuse). Each IP address is reversed and has a domain name attached to
it; for example, the IP address 127.0.0.2 would become 2.0.0.127, and then
a domain such as "relays.visi.com" would be added to it. You
would then try to resolve the result (ie. 2.0.0.127.relays.visi.com);
if you receive a positive reply, then you know that the address is listed.
Further information can also be queried, such as text descriptions of why
the address was listed.
</Para>

<Para>
rblcheck is licensed under the terms of the
<Link linkend="gpl">GNU General Public License</Link>, a free software
license.
</Para>
</Chapter>

<Chapter id="building">
<Title>Building</Title>

<Section id="building-platforms">
<Title>Supported Platforms</Title>

<Para>
I currently perform a manual build and test of rblcheck on the following
platforms prior to each release:
<ItemizedList>
<ListItem><Para>
<ULink url="http://www.redhat.com/">Red Hat</ULink> Linux 7.0/Intel
</Para></ListItem>
<ListItem><Para>
<ULink url="http://www.debian.org/">Debian</ULink> GNU/Linux 2.2r2/Intel
</Para></ListItem>
<ListItem><Para>
<ULink url="http://www.sun.com/">Sun</ULink> Solaris 7/SPARC
</Para></ListItem>
</ItemizedList>
</Para>

<Para>
I speculate that most releases will compile on the following platforms:
<ItemizedList>
<ListItem><Para>
<ULink url="http://www.sun.com/">Sun</ULink> SunOS 4.x
</Para></ListItem>
<ListItem><Para>
<ULink url="http://www.sun.com/">Sun</ULink> Solaris 2.x/7/8
</Para></ListItem>
<ListItem><Para>
<ULink url="http://www.ibm.com/">IBM</ULink> AIX 4.3.3
</Para></ListItem>
<ListItem><Para>
<ULink url="http://www.bsdi.com/">BSDI</ULink> BSD/OS 2.x/3.x/4.x
</Para></ListItem>
<ListItem><Para>
<ULink url="http://www.freebsd.org/">FreeBSD</ULink> 2.x/3.x/4.x
</Para></ListItem>
<ListItem><Para>
<ULink url="http://www.compaq.com/">Compaq</ULink> Digital UNIX/Tru64 4.0x
</Para></ListItem>
<ListItem><Para>
<ULink url="http://www.hp.com/">Hewlett-Packard</ULink> HP/UX 10.x/11.x
</Para></ListItem>
<ListItem><Para>
Most versions of <ULink url="http://www.linux.com/">Linux</ULink>
(libc5- and glibc-based)
</Para></ListItem>
<ListItem><Para>
Almost any relatively POSIX platform with a resolver library.
</Para></ListItem>
</ItemizedList>
</Para>

</Section>

<Section id="building-compiling">
<Title>Compiling</Title>

<Para>
Before building rblcheck, edit the file <Filename>sites.h</Filename> for
the listings you wish to check against (to un-comment a listing, remove
the <ComputerOutput>/*</ComputerOutput> and <ComputerOutput>*/</ComputerOutput>
around the <ComputerOutput>SITE(...)</ComputerOutput> line).
</Para>

<Para>
To compile rblcheck, just run <Application>./configure</Application> in
the main directory, followed by <Application>make</Application> when the
first command is complete.
</Para>

<Para>
To make sure that what you now have works correctly, run <Application>make
check</Application>; make sure that you have an Internet connection handy when
you do, or a large number of the tests will produce (non-fatal) failures.
</Para>

<Para>
When you are done, you can type <Application>make install</Application> to
install the software (by default, everything will be installed in
<Filename class="directory">/usr/local</Filename>.
</Para>

<Para>
For more details on how the <Application>configure</Application> command
works, please see the file <Filename>INSTALL</Filename> in the main directory,
which has a complete breakdown of all of your options.
</Para>
</Section>

<Section id="building-developers">
<Title>Note to developers</Title>
<Para>
You may have received the version of rblcheck that you're currently working
from via a nightly CVS snapshot (the file you downloaded would likely have
been called <Application>rblcheck-20020101.tar.gz</Application> or something
similar), or you might have downloaded a version of the source directly from
the <ULink url="http://sourceforge.net/cvs/?group_id=2081">CVS</ULink>
tree. The most distinguishing feature of these developer-only versions is
the lack of a <Application>configure</Application> script in the main
distribution directory, and the presense of a
<Application>bootstrap</Application> script instead. These releases are not
for the faint of heart, and you may very well be unable to build them
without a bit of work. As a matter of fact, the documentation you're reading
right now may not even apply to one of these experimental versions.
</Para>
<Para>
If you are not building a development release, you do NOT need to read this
section, as none of these instructions apply to you. Please read
<XRef linkend="building-compiling"> for instructions on how to build a
normal rblcheck release.
</Para>
<Para>
And with that out of the way, welcome to rblcheck development! You will need
a number of utilities to build a development release, above and beyond the
usual build requirements:
</Para>
<ItemizedList>
<ListItem><Para>
<ULink url="http://sources.redhat.com/autoconf/">Autoconf</ULink> 2.13
</Para></ListItem>
<ListItem><Para>
<ULink url="http://sources.redhat.com/automake/">Automake</ULink> 1.4
</Para></ListItem>
<ListItem><Para>
<ULink url="http://sources.redhat.com/docbook-tools/">docbook-tools</ULink>
0.6.8 (the Red Hat RPM package identifies itself as docbook-utils, other
distributions may name the package differently, if they include it at all)
</Para></ListItem>
</ItemizedList>
<Para>
Autoconf and automake are tools which make cross-platform development easier
by automatically checking for issues related to particular platforms. The
basic idea is to ensure that even though the primary developers of a piece
of software may not have access to a wide range of platforms, the chances of
a successful "out of the box" build will still work. The reality is a little
different, of course, but it works relatively well. If this sounds like your
cup of tea, you might be interested in reading the definitive book on GNU
Autotools: <ULink url="http://sources.redhat.com/autobook/">GNU Autoconf,
Automake, and Libtool</ULink>.
</Para>
<Para>
The docbook-tools package is required for building multiple formats of the
documentation included with rblcheck. The documentation is written entirely
in SGML (Docbook 4.1), and is located in the file
<Filename>docs/rblcheck.sgml</Filename>.
</Para>
<Para>
Once you've verified that you have these installed, you'll need to run
<Application>./bootstrap</Application> from the main rblcheck source
directory, which will create a number of the files you need to complete
the build. At this point, you should follow the usual instructions for
building the application (see <XRef linkend="building-compiling">).
</Para>
</Section>

<Section id="building-distributors">
<Title>Note to distributors and packagers</Title>

<Para>
If you're distributing a pre-built version of rblcheck for your users, I
strongly recommend leaving everything in <Filename>sites.h</Filename>
commented out. The ability to add sites there was only added as a convenience
feature for people building a personal copy for their own use, and was never
intended to be used to pre-set policy for people using pre-packaged versions.
</Para>
<Para>
Over the years, there has been a great deal of volatility in the RBL listing
"market"; even the venerable MAPS RBL is no longer publically available
without making special arrangements. Therefore, along with those pre-defined
lists of RBL services is built-in obsolescence.
</Para>
<Para>
As a side-note, I don't make new releases just to update the
<Filename>sites.h</Filename> file, and at some point in the future, I'll
probably stop seeding it with suggestions. As the package maintainer, you're
taking on the burden of keeping that up-to-date. Do you really want that
hassle, or would it just be easier to point your users at a list of RBL
services that is up-to-date (see the
<ULink url="http://rblcheck.sourceforge.net/">rblcheck homepage</ULink>
for links to several current listings)?
</Para>
<Para>
You're also making life a more difficult for the user; users will come to
depend on that pre-built list of sites. What happens when, by necessity, you
need to change that built-in list (because some listings are no longer
available, or because new ones are now online)? Your users will very likely
complain about the change in behavior, and rightly so. Even worse, what does
the user do when they disagree with your selection of services? Recompile
from source (which defeats the purpose of providing them with a pre-compiled
binary in the first place)? Let them pick their own listings. You and your
users will be much happier.
</Para>
<Para>
If you feel that you just can't release rblcheck without a built-in list,
may I suggest using the global <Filename>rblcheckrc</Filename> which the
<Application>rbl</Application> script uses? At least that way, the end
user can change your pre-selections on their own, without having to build
from source.
</Para>
</Section>
</Chapter>

<Chapter id="using">
<Title>Using</Title>

<Section id="using-rblcheck">
<Title>rblcheck basics</Title>

<Para>
The program has several command line options:
</Para>

<InformalTable frame="none">
<TGroup cols="2">
<TBody>
<Row>
<Entry><Option>-q</Option></Entry>
<Entry><Para>
Display only listed addresses, if none is listed then there is no output.
</Para></Entry>
</Row>
<Row>
<Entry><Option>-t</Option></Entry>
<Entry><Para>
Display, if available, a textual description of why the site was
originally placed in a particular listing.
</Para></Entry>
</Row>
<Row>
<Entry><Option>-m</Option></Entry>
<Entry><Para>
Stop checking listings after the first successful match of any IP
address against any listing.
</Para></Entry>
</Row>
<Row>
<Entry><Option>-l</Option></Entry>
<Entry><Para>List the currently defined RBL listings. By default, rblcheck has no pre-defined listings; you can change this behavior by editing the file <Filename>sites.h</Filename> as described in <XRef linkend="building">.</Para></Entry>
</Row>
<Row>
<Entry><Option>-c</Option></Entry>
<Entry><Para>
Clear the list of defined RBL listings. This is handy if you don't
want to use the default listings added by the installation of 
rblcheck on your system.
</Para></Entry>
</Row>
<Row>
<Entry><Option>-s</Option> <Parameter>&lt;service&gt;</Parameter></Entry>
<Entry><Para>
Toggle a service in the list of defined RBL listings.
</Para></Entry>
</Row>
<Row>
<Entry><Option>-h</Option>, <Option>-?</Option></Entry>
<Entry><Para>
Get help about rblcheck.
</Para></Entry>
</Row>
<Row>
<Entry><Option>-v</Option></Entry>
<Entry><Para>
Display the version of rblcheck.
</Para></Entry>
</Row>
</TBody>
</TGroup>
</InformalTable>

<Para>
You can check multiple addresses at once, to make life a little easier
with scripts; just add additional addresses on the command line after all
of the options. By specifying an address of "-", rblcheck will read from
stdin and perform a lookup on every line of input (if it is a valid IP
address).
</Para>
</Section>

<Section id="using-returncodes">
<Title>Return codes</Title>

<Para>
When invoked, rblcheck returns either 0 (to indicated error, or that the
address was not in any of the listings), or a positive number (indicating
the number of listings that the IP address was found in).
</Para>
</Section>

<Section id="using-verification">
<Title>Verifying your installation</Title>

<Para>
To verify that the program is working after you've compiled it, try the
following test:
</Para>

<Screen>$ ./rblcheck -s relays.ordb.org 127.0.0.1
127.0.0.1 not RBL filtered by relays.ordb.org
$ ./rblcheck -s relays.ordb.org 127.0.0.2
127.0.0.2 RBL filtered by relays.ordb.org</Screen>

<Para>
If you see any other result than the above, then something has gone wrong;
please see below about reporting bugs and finding help.
</Para>
</Section>

<Section id="using-rbl">
<Title>The rbl wrapper</Title>

<Para>
A recent addition to the rblcheck package is the <Application>rbl</Application>
shell script, which is a simple wrapper around rblcheck, with one special
feature: it will read a global <Filename>rblcheckrc</Filename> (usually
in <Filename class="directory">/etc</Filename> or
<Filename class="directory">/usr/etc</Filename>), and then
a <Filename>.rblcheckrc</Filename> from the current user's home directory.
These files can contain any of the usual <Application>rblcheck</Application>
command-line arguments (see <XRef linkend="using-rblcheck">), but are most
useful for setting the most common RBL-style listings you use day-to-day.
</Para>

<Para>
For example, your personal <Filename>.rblcheckrc</Filename> might contain:
</Para>

<Screen>-t
-m
-c
-s relays.ordb.org
-s relays.visi.com
-s some.future.rbl.listing</Screen>

<Para>
Please note that for mail filtering, or any performance-sensitive use, you
should use <Application>rblcheck</Application> directly, to avoid adding
additional latency to the process. <Application>rbl</Application> is
mainly intended as a convenience tool for interactive use.
</Para>
</Section>
</Chapter>

<Chapter id="thirdparty">
<Title>Third-Party Software</Title>
<Para>
rblcheck works well as a command-line tool for performing lookups, but it
also serves an important role working with other software, such as mail
servers and email filtering programs.
</Para>

<Section id="thirdparty-procmail">
<Title>Procmail</Title>

<Para>
rblcheck was really designed to be used with procmail, as long as you have
access to the IP address of the system sending you email. Surprisingly,
most MTAs make obtaining this information more difficult than it needs to
be. The procmail rule I present here assumes you've found some way to put
the IP address of the sender in the variable <EnVar>TCPREMOTEIP</EnVar>.
See the sections below on Sendmail and QMail for ideas on how you can get
ahold of this value.
</Para>

<Para>
The following procmail rule will, once you have <EnVar>TCPREMOTEIP</EnVar>,
use rblcheck to look up the IP address in the built-in filters:
</Para>

<ProgramListing>:0
* ! ? if [ -n "$TCPREMOTEIP" ]; then rblcheck -q "$TCPREMOTEIP"; fi
{
	EXITCODE=100
	LOGABSTRACT=all
	LOG="Filter: RBL-filtered address: \"$TCPREMOTEIP\"
"
	:0:
	$FILTER_FOLDER
}</ProgramListing>

<Para>
<EnVar>FILTERFOLDER</EnVar> is assumed to have been set up ahead of
time as the place to put email that you don't want to see (either another
incoming folder, /dev/null, or a 'formail' invokation that rewrites the
message and tacks on an extra header or munges the subject so you can
easily identify it.
</Para>

<Para>
Note that <EnVar>EXITCODE</EnVar> above is for QMail, and indicates a
permanent error. Under Sendmail, 77 is more appropriate. Under anything
else, it's hard to say; your best bet is to refer to the documentation
regarding execution of programs.
</para>

<Para>
One more thing: procmail has a nasty habit of munging the environment, but
most MTAs already do this for you. Hence, you should add the '-p' flag to
the invokation of procmail (either from a local delivery rule in Sendmail,
or from a .forward or .qmail file). This will ensure that procmail doesn't
clean out the value of <EnVar>TCPREMOTEIP</EnVar>.
</Para>

<Para>
To test the procmail recipe:
</Para>

<OrderedList>
<ListItem>
<Para>
Save any mail message, with full headers, to a file.
</Para>
</ListItem>
<ListItem>
<Para>
Run procmail with the environment variable <EnVar>TCPREMOTEIP</EnVar> set
to an offending address, and with the message you just saved as input:
<Screen>cat message | env - TCPREMOTEIP=127.0.0.2 procmail -p</Screen>
</Para>
</ListItem>
<ListItem>
<Para>
Check your procmail log and mailbox. If the message went through,
you have a problem. If you have a message in your logfile stating
that the message was bounced for being in the RBL, you're fine.
</Para>
</ListItem>
<ListItem>
<Para>
Run procmail with the environment variable <EnVar>TCPREMOTEIP</EnVar> set
to a non-filtered address, such as 127.0.0.1, and with the message as input:
<Screen>cat message | env - TCPREMOTEIP=127.0.0.1 procmail -p</Screen>
</Para>
</ListItem>
<ListItem>
<Para>
Check your procmail log and mailbox. If the message didn't go
through, you have a problem. If you have a copy of the message in
your mailbox, and no errors in your log file, you're fine.
</Para>
</ListItem>
</OrderedList>
</Section>

<Section id="thirdparty-sendmail">
<Title>Sendmail</Title>

<Para>
This solution for obtaining the IP address of the connecting host could be
considered to be a bit of a hack, but it works quite reliably. If you're
an ordinary user on your system, you won't be able to use this; talk to
your system administrator about the possibility of installing the
sendmail.cf patch below. Point them at this file as a source of
information.
</Para>

<Para>
Currently, in your sendmail.cf file, you'll probably have something like:
</Para>

<ProgramListing>
Mlocal,	P=/bin/mail, F=lsDFMAw5:/|@SnE, S=10/30, R=20/40,
	T=DNS/RFC822/X-Unix,
	A=mail -f $g -d $u
</ProgramListing>

<Para>
Or, if you're using procmail as the local delivery agent:
</Para>

<ProgramListing>
Mlocal,	P=/usr/bin/procmail, F=lsDFMAw5:/|@ShPfn, S=10/30, R=20/40,
	T=DNS/RFC822/X-Unix,
	A=procmail -a $h -d $u
</ProgramListing>

<Para>
This is the local delivery rule used to execute .forward scripts.  Your
system might use something like <Application>rsh</Application> or another
restricted shell instead of <Application>sh</Application> for running
programs. Don't let that scare you; they all basically work the same.
</Para>

<Para>
Change the above lines to look like this (there will also be Mprog lines
which look similar; you can modify them in exactly the same manner):
</Para>

<ProgramListing>
Mlocal,	P=/usr/bin/env, F=lsDFMAw5:/|@SnE, S=10/30, R=20/40,
	T=DNS/RFC822/X-Unix,
	A=env TCPREMOTEIP="${client_addr}" mail -f $g -d $u
</ProgramListing>

<Para>
(replacing "mail -f $g -d $u" with "procmail -a $h -d $u" appropriately.)
</Para>

<Para>
ONLY change the P=... and A=... entries. Most certainly do not mess with
F=... unless you know what you are doing.
</Para>

<Para>
This will create an environment variable <EnVar>TCPREMOTEIP</EnVar>, which
you can now use with rblcheck to determine if the address has been blocked.
To test this, set up an alias like:
</Para>

<Screen>foo: |mailx -s "$TCPREMOTEIP" user@domain.com</Screen>

<Para>
Then, send email to the alias "foo" (or whatever). You should
immediately get a piece of email with the IP address which sent the
message in the subject line. (Replace <Application>mailx</Application>
with <Application>mail</Application> on some systems.)
</Para>

<Para>
This is about the most efficient means of getting this information to
executed programs that I can see with sendmail. What would -really- be
nice here would be a way to program how Sendmail sets up the environment
before executing an external program, at the point of execution. Bug the
Sendmail developers if you agree with me. ;-)
</Para>
</Section>

<Section id="thirdparty-qmail">
<Title>QMail</Title>

<Para>
Getting this going under QMail turns out to be a real challenge, since
QMail doesn't have the same level of programmability that Sendmail has.
Hence, we need to employ an additional script to grab the IP address from
the headers. (Thanks to Russell Nelson for confirming QMail's behavior
here.)
</Para>

<Para>
QMail has a very specific means of adding Received: lines to messages,
making them relatively easy to parse. For example, the following headers
are typical:
</Para>

<ProgramListing>
Return-Path: &lt;emarshal@xnet.com&gt;
Delivered-To: emarshal@LOGIC.NET
Received: (qmail 26029 invoked from network); 13 Oct 1997 15:04:13 -0000
Received: from quake.xnet.com (HELO mail.xnet.com) (198.147.221.35)
  by labyrinth.logic.net with SMTP; 13 Oct 1997 15:04:13 -0000
</ProgramListing>

<Para>
We can disregard the Return-Path: and Delivered-To: lines; they're
unimportant to us. The Received: headers are the most interesting. The
first Received: line we'll see is the local delivery of the mail; hence,
the "qmail 2609 invoked from network". The second Received: line is the
most important to us; it's the one which contains the IP address of the
sender...in this case, 198.147.221.35. To complicate things, the "(HELO
mail.xnet.com)" section may not exist, and the IP address might have ident
information prepended to it (like "qmailr@198.147.221.35").
</Para>

<Para>
Two programs are provided to help you retrieve this information
automatically from the headers, both with the same semantics. "origip.c"
compiles into "origip", and for those who have trouble compiling it (if
you do, please email me with any errors), "origip.awk" is provided which
behaves the same way.
</Para>

<Para>
Essentially, you pass either of these programs an email message, and they
in turn extract the sending address and either print it back to you, or
exit with a non-zero return value.
</Para>

<Para>
To use this in procmail, just use:
</Para>

<Screen>TCPREMOTEIP=`origip || echo 127.0.0.1`</Screen>

<Para>
This will pipe the message through origip (replace origip with
"origip.awk" in the case of using the awk script), and will capture the
address. If there is an error, we'll default to 127.0.0.1, which will
allow the mail through.
</Para>

<Para>
(If you're undecided which program of the two you want to use, consider
that the C version is much faster, and will be maintained more than the
awk script. However, the C version is probably more prone to bugs. ;-)
</Para>

<Para>
Once you have that line in place, go ahead and use the procmail recipe
supplied above in good health.
</Para>
</Section>

<Section id="thirdparty-inetd-smtpd">
<Title>inetd and smtpd</Title>

<Para>
If you use an smtp server which runs from inetd (sendmail can operate this
way, as can QMail and a number of other MTAs), here's a good way to do
site-wide filtering using rblcheck; add the following to /etc/hosts.allow:
</Para>

<ProgramListing>
smtpd: ALL: spawn /usr/local/bin/rblcheck -q %a &amp;&amp; \
	exec /usr/local/bin/smtpd || /bin/echo \
	"469 Connection refused. See http://maps.vix.com/rbl/\r\b\r\n"
</ProgramListing>

<Para>
This gives you RBL support on a site-wide basis, even if native support
doesn't yet exist for your MTA of choice. This assumes that your inetd has
support for tcp_wrappers checks; many Linux variants fall into this
category, but other platforms may differ.
</Para>

<Para>
A word of warning, however: there are a number of very good reasons to not
run a production mail server from inetd, which I won't elaborate on here.  
You might want to investigate more secure and reliable alternatives, such
as tcpserver from D. J. Bernstein's excellent
<ULink url="http://cr.yp.to/daemontools.html">daemontools</ULink> package.
</Para>
</Section>

<Section id="thirdparty-other">
<Title>Other Software</Title>

<Para>
Don't ask me. If you figure out a way to make this work under another
setup, let me know how you did it, and I'll add it here. If you find
better ways of doing this than the ones I'm using above, let me know too,
and you'll see your idea show up in here in the next release.
</Para>
</Section>
</Chapter>

<Chapter id="future">
<Title>Future</Title>

<Section id="future-todo">
<Title>To Do</Title>

<Para>
There are a number of enhancements to rblcheck that are up for
consideration, in no particular order. Patches for any of the below
will earn you fame, fortune, and a warm fuzzy feeling for having
made the world a better place. ;-)
</Para>

<ItemizedList>
<ListItem><Para>
Follow CNAMEs from rblcheck(). This will let us get at the eventual
TXT RRs for a domain name.
</Para></ListItem>

<ListItem><Para>
Optional support for
<ULink url="http://www.gnu.org/software/adns/adns.html">adns</ULink>.
</Para></ListItem>

<ListItem><Para>
Timeout option. Should default to no timeout, but apparently there is
an issue with rblcheck hanging in an offline environment where the
nameserver in use is located off-site. This would compensate for the
misconfiguration, and provide a 'quick-fail' mode for people to play
with. I'm still not entirely convinced that this should be rblcheck's
problem, though; using a local cache like dnscache from
<ULink url="http://cr.yp.to/djbdns.html">djbdns</ULink> seems like a
much more reliable solution to what is a general misconfiguration.
</Para></ListItem>

<ListItem><Para>
(from Aaron Schrab <EMail>aaron@schrab.com</EMail>, era eriksson
<EMail>era@iki.fi</EMail>, and torben fjerdingstad
<EMail>tfj@fjerdingstad.dk</EMail>) Add the ability to only list successful
matches, and add a debug mode which outputs what is happening internally,
and any errors received. This could be best implemented with a '-v X'
option, where 'X' is a number between 0 and 9 (0 being silent, 4 being
default/ordinary output, 9 displaying heavy debugging info).
</Para></ListItem>

<ListItem><Para>
Add an option to display the PTR address returned by the original query,
prior to following it.
</Para></ListItem>

<ListItem><Para>
(from Craig Callender <EMail>craig@mosquitonet.com</EMAIL>)
Add the ability to specify a particular PTR address; for example, when
performing a lookup in ORBS, allow for matching against only a specific
returned address (such as 127.0.0.2). Perhaps allow a list of these
matches. The question is: is this better implemented here, or in the
caller via a filter (after the display of PTR addresses is added)?
</Para></ListItem>
</ItemizedList>

</Section>

<Section id="future-nottodo">
<Title>...or Not To Do?</Title>

<Para>
These are the features that you'll never see in the version of rblcheck
that I produce (rblcheck is GPL; you're free to produce your own version
if this doesn't suit you well), and the rationale behind why not. I'm
hoping that the explainations will make sense, but I'm always open to
criticism if you feel my logic is flawed.
</Para>

<VariableList>
<VarListEntry>
<Term>Support for doing lookups of FQDNs</Term>
<ListItem>
<Para>
This is a futile method of checking whether a particular system is
blackholed; if the originating system has control of reverse DNS for
their IP space, they can make their IP address resolve to anything
they want, such as system.network.com. If rblcheck were to do a lookup
on that, "system.network.com" might resolve to anything (such as
"127.0.0.1, which will always pass with every currently known
RBL-based blacklist). A compromise that I've considered would be
similar to TCP Wrapper's system of multiple lookups: take the IP
address, look up the reverse, then resolve the reverse to an IP
address. If both lookups match, then proceed, otherwise exit with a
failure. I'd consider integrating code from someone who implemented
this behavior.
</Para>
<Para>
(A note for the confused: some people might mistake this for my saying
that a tool for looking up hosts in DNSBL listings (a means of looking up
originating domains in a blacklist, much like the RBL) isn't a good idea.
On the contrary, I'd like to see a complimentary dnsblcheck to go along
with rblcheck. The problem I have is specifically with resolving the name
to an IP address for use by an RBL lookup tool.)
</Para>
</ListItem>
</VarListEntry>

<VarListEntry>
<Term>Return codes that identify a particular blacklist</Term>
<ListItem>
<Para>
This took a while to convince me it was wrong. Here are the questions I went
over when deciding against this:
</Para>
<ItemizedList>
<ListItem><Para>
What do you do with your scripts when the blacklist order changes, or new
blacklists appear (assuming a dynamic assignment of identifiers)?
</Para></ListItem>
<ListItem><Para>
If you hard-code a number for each and every blacklist, who becomes
responsible for being a registry for those numerical identifiers? What
happens to already-assigned values when blacklists shutdown or change
incompatibly?
</Para></ListItem>
<ListItem><Para>
How do you scale beyond 256 RBL services? With the advent of software such as
<ULink url="http://cr.yp.to/djbdns/rbldns.html">rbldns</ULink> (a part of the
<ULink url="http://cr.yp.to/djbdns.html">djbdns</ULink> package which allows
anyone to host an RBL-style service), and with nearly a dozen
<ULink url="http://relays.osirusoft.com/">OsiruSoft</ULink> domains alone,
does this limitation seem reasonable?
</Para></ListItem>
<ListItem><Para>
How do you report multiple matches with a return code, when the return code
can only hold one number?
</Para></ListItem>
</ItemizedList>
<Para>
Some of these can be solved, but not cleanly; you'll need no end of special
cases to accomodate them.
</Para>
</ListItem>
</VarListEntry>

<VarListEntry>
<Term>Integrated scanning of email and similar features</Term>
<ListItem>
<Para>
This is a question of UNIX philosophy: design one tool for one task,
and do it well. There are plenty of far more powerful text parsing
tools available which are more appropriate for the job (email parsing
is easily handled by tools such as formail, general text parsing is
better suited by tools such as sed, awk, perl, python, etc), and they
can do a much better job than something that I could integrate into
rblcheck while still maintaining a small footprint.
</Para>
</ListItem>
</VarListEntry>
</VariableList>

</Section>

</Chapter>

<Chapter id="origip">
<Title>Notes on origip</Title>

<Para>
Not convinced that you should use the C version of origip? Here's some
data (using test_origip.sh as a testbed) which definitely speaks volumes:
</Para>

<Para>
With origip.awk:
</Para>

<Screen>18.60user 22.46system 0:43.59elapsed 94%CPU (0avgtext+0avgdata 0maxresident)k
0inputs+0outputs (102172major+51041minor)pagefaults 0swaps</Screen>

<Para>
With origip.c:
</Para>

<Screen>13.16user 19.41system 0:33.73elapsed 96%CPU (0avgtext+0avgdata 0maxresident)k
0inputs+0outputs (71381major+46044minor)pagefaults 0swaps</Screen>

<Para>
10 seconds faster, 3 seconds less system time used, 5 seconds less user
time, and over 30,000 less page faults. In other words: a LOT easier on
the box you'll be running this on. This test was run on a little under 600
messages, from various mailing lists and private messages, on a Linux
2.0.31 system.
</Para>
</Chapter>

<Chapter id="problems">
<Title>Reporting Problems</Title>

<Para>
All software has bugs, and rblcheck has a place for you to report them if
you believe you've found one.
(<ULink url="https://github.com/rfc1036/rblcheck/issues">Bug tracker</ULink>)
</Para>

<Para>
If you have a SourceForge account already, please log in before reporting
a bug so that you can be notified of changes.
</Para>
</Chapter>

<Chapter id="credits">
<Title>Credits</Title>

<Para>Thanks, kudos, and other good stuff go to:</Para>

<Para>
<VariableList>
<VarListEntry>
<Term>Paul Vixie <EMail>paul@vix.com</EMail></Term>
<ListItem<Para>
For the original RBL, a fantastic tool for the prevention of spam. Often
duplicated, never repeated, and all that jazz.
</Para></ListItem>
</VarListEntry>
<VarListEntry>
<Term><ULink url="http://mail-abuse.org/">The MAPS Project</ULink></Term>
<ListItem><Para>
A great gathering point for protection services regarding email. Everyone
there should be given a pat on the back for the thankless hours they put
into maintaining an excellent resource for everyone.
</Para></ListItem>
</VarListEntry>
<VarListEntry>
<Term>Stephen R. van den Berg <EMail>srb@cuci.nl</EMail></Term>
<ListItem><Para>
For writing <ULink url="http://www.procmail.org/">Procmail</ULink>, a nifty
little mail filtering tool. While certainly not the only place to use
rblcheck, it's certainly one of the more useful.
</Para></ListItem>
</VarListEntry>
<VarListEntry>
<Term><ULink url="http://www.money-for-nothing.org/">Dire Straits</ULink></Term>
<ListItem><Para>
For writing good music to write code to. ;-) I wonder if spam qualifies as
a symptom of <ULink
url="http://gunther.simplenet.com/v/data/industri.htm">industrial
disease</ULink>?
</Para></ListItem>
</VarListEntry>
<VarListEntry>
<Term>...and a cast of thousands:</Term>
<ListItem><ItemizedList>
<ListItem><Para>
Russell Nelson <EMail>nelson@crynwr.com</EMail>
</Para></ListItem>
<ListItem><Para>
Frank Tegtmeyer <EMail>fte@iqweb.de</EMail>
</Para></ListItem>
<ListItem><Para>
Anders Eriksson <EMail>aer@cdt.luth.se</EMail>
</Para></ListItem>
<ListItem><Para>
Kevin Kadow <EMail>kadokev@ripco.com</EMail>
</Para></ListItem>
<ListItem><Para>
Ronald F. Guilmette <EMail>rfg@monkeys.com</EMail>
</Para></ListItem>
<ListItem><Para>
era eriksson <EMail>era@iki.fi</EMail>
</Para></ListItem>
<ListItem><Para>
Ophir Ronen <EMail>ophir@internap.com</EMail>
</Para></ListItem>
<ListItem><Para>
Brian Willoughby <EMail>brianw@sounds.wa.com</EMail>
</Para></ListItem>
<ListItem><Para>
Jeff A. Earickson <EMail>jaearick@colby.edu</EMail>
</Para></ListItem>
<ListItem><Para>
Gerald Pfeifer <EMail>pfeifer@dbai.tuwien.ac.at</EMail>
</Para></ListItem>
<ListItem><Para>
Pat Myrto <EMail>pat@rwing.COM</EMail>
</Para></ListItem>
<ListItem><Para>
William Yang <EMail>wyang@freenet.columbus.oh.us</EMail>
</Para></ListItem>
<ListItem><Para>
Dougal Campbell <EMail>dougal@advicom.net</EMail>
</Para></ListItem>
<ListItem><Para>
Jason Gunthorpe <EMail>jgg@gpu.srv.ualberta.ca</EMail>
</Para></ListItem>
<ListItem><Para>
Timothy J Luoma <EMail>luomat@peak.org</EMail>
</Para></ListItem>
<ListItem><Para>
Adam Shand <EMail>larry@alaska.net</EMail>
</Para></ListItem>
<ListItem><Para>
Andrew Kelley <EMail>kelleya@dimensional.com</EMail>
</Para></ListItem>
<ListItem><Para>
Thomas Meyer <EMail>tmeyer@ifi.unizh.ch</EMail>
</Para></ListItem>
<ListItem><Para>
Jonathan Bradshaw <EMail>jonathan@NrgUp.Com</EMail>
</Para></ListItem>
<ListItem><Para>
Jacques Distler <EMail>distler@golem.ph.utexas.edu</EMail>
</Para></ListItem>
<ListItem><Para>
Harlan Stenn <EMail>Harlan.Stenn@pfcs.com</EMail>
</Para></ListItem>
<ListItem><Para>
Marco d'Itri <EMail>md@Linux.IT</EMail>
</Para></ListItem>
</ItemizedList></ListItem>
</VarListEntry>
</VariableList>
</Para>
</Chapter>

</Part>

<Part id="appendixes">
<Title>Appendixes</Title>

<!-- 
     The GNU Public License 2 in DocBook
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<appendix id="gpl">
  <appendixinfo>
    <releaseinfo>
      Version 2, June 1991
    </releaseinfo>
    <copyright>
      <year>2000</year>
      <holder>Free Software Foundation, Inc.</holder>
    </copyright>
    <legalnotice id="gpl-legalnotice">
      <para>
	<address>Free Software Foundation, Inc. 
	  <street>59 Temple Place, Suite 330</street>, 
	  <city>Boston</city>, 
	  <state>MA</state> <postcode>02111-1307</postcode>
	  <country>USA</country>
	</address>.
      </para>
      <para>
	Everyone is permitted to copy and distribute verbatim copies
	of this license document, but changing it is not allowed.
      </para>
    </legalnotice>
  </appendixinfo>
  <title>GNU General Public License</title>

  <sect1 id="gpl-preamble">
    <title>Preamble</title>
    
    <para>
      The licenses for most software are designed to take away your 
      freedom to share and change it. By contrast, the GNU General Public 
      License is intended to guarantee your freedom to share and change 
      free software - to make sure the software is free for all its users. 
      This General Public License applies to most of the Free Software 
      Foundation's software and to any other program whose authors commit 
      to using it. (Some other Free Software Foundation software is covered 
      by the GNU Library General Public License instead.) You can apply it 
      to your programs, too.
    </para>

    <para>
      When we speak of free software, we are referring to freedom, not price. 
      Our General Public Licenses are designed to make sure that you have the 
      freedom to distribute copies of free software (and charge for this 
      service if you wish), that you receive source code or can get it if you 
      want it, that you can change the software or use pieces of it in new free 
      programs; and that you know you can do these things.
    </para>

    <para>
      To protect your rights, we need to make restrictions that forbid anyone 
      to deny you these rights or to ask you to surrender the rights. These 
      restrictions translate to certain responsibilities for you if you distribute 
      copies of the software, or if you modify it.
    </para>

    <para>
      For example, if you distribute copies of such a program, whether gratis or 
      for a fee, you must give the recipients all the rights that you have. You 
      must make sure that they, too, receive or can get the source code. And you 
      must show them these terms so they know their rights.
    </para>

    <para>
      We protect your rights with two steps:

      <orderedlist numeration="arabic">
	<listitem>
	  <para>
	    copyright the software, and
	  </para>
	</listitem>
	<listitem>
	  <para>
	    offer you this license which gives you legal permission to copy, 
	    distribute and/or modify the software.
	  </para>
	</listitem>
      </orderedlist>
    </para>

    <para>
      Also, for each author's protection and ours, we want to make certain that 
      everyone understands that there is no warranty for this free software. If 
      the software is modified by someone else and passed on, we want its 
      recipients to know that what they have is not the original, so that any 
      problems introduced by others will not reflect on the original authors' 
      reputations.
    </para>

    <para>
      Finally, any free program is threatened constantly by software patents. 
      We wish to avoid the danger that redistributors of a free program will 
      individually obtain patent licenses, in effect making the program 
      proprietary. To prevent this, we have made it clear that any patent must be 
      licensed for everyone's free use or not licensed at all.
    </para>

    <para>
      The precise terms and conditions for copying, distribution and modification 
      follow.
    </para>

  </sect1>

  <sect1 id="gpl-terms">
    <title>TERMS AND CONDITIONS FOR COPYING, DISTRIBUTION AND MODIFICATION</title>

    <sect2 id="gpl-sect0">
      <title>Section 0</title>
      <para>
	This License applies to any program or other work which contains a notice 
	placed by the copyright holder saying it may be distributed under the terms 
	of this General Public License. The "Program", below, refers to any such 
	program or work, and a <quote>work based on the Program</quote> means either 
	the Program or any derivative work under copyright law: that is to say, a 
	work containing the Program or a portion of it, either verbatim or with 
	modifications and/or translated into another language. (Hereinafter, translation 
	is included without limitation in the term <quote>modification</quote>.) Each 
	licensee is addressed as <quote>you</quote>.
      </para>

      <para>
	Activities other than copying, distribution and modification are not covered by 
	this License; they are outside its scope. The act of running the Program is not 
	restricted, and the output from the Program is covered only if its contents 
	constitute a work based on the Program (independent of having been made by running 
	the Program). Whether that is true depends on what the Program does.
      </para>
    </sect2>

    <sect2 id="gpl-sect1">
      <title>Section 1</title>
      <para>
	You may copy and distribute verbatim copies of the Program's source code as you 
	receive it, in any medium, provided that you conspicuously and appropriately 
	publish on each copy an appropriate copyright notice and disclaimer of warranty; 
	keep intact all the notices that refer to this License and to the absence of any 
	warranty; and give any other recipients of the Program a copy of this License 
	along with the Program.
      </para>
      
      <para>
	You may charge a fee for the physical act of transferring a copy, and you may at 
	your option offer warranty protection in exchange for a fee.
      </para>
    </sect2>

    <sect2 id="gpl-sect2">
      <title>Section 2</title>
      <para>
	You may modify your copy or copies of the Program or any portion of it, thus 
	forming a work based on the Program, and copy and distribute such modifications 
	or work under the terms of <link linkend="gpl-sect1">Section 1</link> above, provided 
	that you also meet all of these conditions:

	<orderedlist numeration="loweralpha">
	  <listitem>
	    <para>
	      You must cause the modified files to carry prominent notices stating that 
	      you changed the files and the date of any change.
	    </para>
	  </listitem>
	  <listitem>
	    <para>
	      You must cause any work that you distribute or publish, that in whole or 
	      in part contains or is derived from the Program or any part thereof, to be 
	      licensed as a whole at no charge to all third parties under the terms of 
	      this License.
	    </para>
	  </listitem>
	  <listitem>
	    <para>
	      If the modified program normally reads commands interactively when run, you 
	      must cause it, when started running for such interactive use in the most 
	      ordinary way, to print or display an announcement including an appropriate 
	      copyright notice and a notice that there is no warranty (or else, saying 
	      that you provide a warranty) and that users may redistribute the program 
	      under these conditions, and telling the user how to view a copy of this 
	      License. 

	      <note>
		<title>Exception:</title>
		<para>
		  If the Program itself is interactive but does not normally print such an 
		  announcement, your work based on the Program is not required to print an 
		  announcement.) 
		</para>
	      </note>

	    </para>
	  </listitem>
	</orderedlist>
      </para>

      <para>
	These requirements apply to the modified work as a whole. If identifiable sections 
	of that work are not derived from the Program, and can be reasonably considered 
	independent and separate works in themselves, then this License, and its terms, 
	do not apply to those sections when you distribute them as separate works. But when 
	you distribute the same sections as part of a whole which is a work based on the 
	Program, the distribution of the whole must be on the terms of this License, whose 
	permissions for other licensees extend to the entire whole, and thus to each and 
	every part regardless of who wrote it.
      </para>

      <para>
	Thus, it is not the intent of this section to claim rights or contest your rights 
	to work written entirely by you; rather, the intent is to exercise the right to control 
	the distribution of derivative or collective works based on the Program.
      </para>

      <para>
	In addition, mere aggregation of another work not based on the Program with the Program 
	(or with a work based on the Program) on a volume of a storage or distribution medium 
	does not bring the other work under the scope of this License.
      </para>
    </sect2>

    <sect2 id="gpl-sect3">
      <title>Section 3</title>

      <para>
	You may copy and distribute the Program (or a work based on it, under 
	<link linkend="gpl-sect2">Section 2</link> in object code or executable form under the terms of 
	<link linkend="gpl-sect1">Sections 1</link> and <link linkend="gpl-sect2">2</link> above provided that 
	you also do one of the following:

	<orderedlist numeration="loweralpha">
	  <listitem>
	    <para>
	      Accompany it with the complete corresponding machine-readable source code, which 
	      must be distributed under the terms of Sections 1 and 2 above on a medium 
	      customarily used for software interchange; or,
	    </para>
	  </listitem>
	  <listitem>
	    <para>
	      Accompany it with a written offer, valid for at least three years, to give any 
	      third party, for a charge no more than your cost of physically performing source 
	      distribution, a complete machine-readable copy of the corresponding source code, 
	      to be distributed under the terms of Sections 1 and 2 above on a medium customarily 
	      used for software interchange; or,
	    </para>
	  </listitem>
	  <listitem>
	    <para>
	      Accompany it with the information you received as to the offer to distribute 
	      corresponding source code. (This alternative is allowed only for noncommercial 
	      distribution and only if you received the program in object code or executable form 
	      with such an offer, in accord with Subsection b above.)
	    </para>
	  </listitem>
	</orderedlist>
      </para>

      <para>
	The source code for a work means the preferred form of the work for making modifications 
	to it. For an executable work, complete source code means all the source code for all modules 
	it contains, plus any associated interface definition files, plus the scripts used to control 
	compilation and installation of the executable. However, as a special exception, the source 
	code distributed need not include anything that is normally distributed (in either source or 
	binary form) with the major components (compiler, kernel, and so on) of the operating system 
	on which the executable runs, unless that component itself accompanies the executable.
      </para>
      
      <para>
	If distribution of executable or object code is made by offering access to copy from a 
	designated place, then offering equivalent access to copy the source code from the same place 
	counts as distribution of the source code, even though third parties are not compelled to 
	copy the source along with the object code.
      </para>
    </sect2>

    <sect2 id="gpl-sect4">
      <title>Section 4</title>
      
      <para>
	You may not copy, modify, sublicense, or distribute the Program except as expressly provided 
	under this License. Any attempt otherwise to copy, modify, sublicense or distribute the 
	Program is void, and will automatically terminate your rights under this License. However, 
	parties who have received copies, or rights, from you under this License will not have their 
	licenses terminated so long as such parties remain in full compliance.
      </para>
    </sect2>

    <sect2 id="gpl-sect5">
      <title>Section 5</title>

      <para>
	You are not required to accept this License, since you have not signed it. However, nothing 
	else grants you permission to modify or distribute the Program or its derivative works. 
	These actions are prohibited by law if you do not accept this License. Therefore, by modifying 
	or distributing the Program (or any work based on the Program), you indicate your acceptance 
	of this License to do so, and all its terms and conditions for copying, distributing or 
	modifying the Program or works based on it.
      </para>
    </sect2>

    <sect2 id="gpl-sect6">
      <title>Section 6</title>

      <para>
	Each time you redistribute the Program (or any work based on the Program), the recipient 
	automatically receives a license from the original licensor to copy, distribute or modify 
	the Program subject to these terms and conditions. You may not impose any further restrictions 
	on the recipients' exercise of the rights granted herein. You are not responsible for enforcing 
	compliance by third parties to this License.
      </para>
    </sect2>

    <sect2 id="gpl-sect7">
      <title>Section 7</title>

      <para>
	If, as a consequence of a court judgment or allegation of patent infringement or for any other 
	reason (not limited to patent issues), conditions are imposed on you (whether by court order, 
	agreement or otherwise) that contradict the conditions of this License, they do not excuse you 
	from the conditions of this License. If you cannot distribute so as to satisfy simultaneously 
	your obligations under this License and any other pertinent obligations, then as a consequence 
	you may not distribute the Program at all. For example, if a patent license would not permit 
	royalty-free redistribution of the Program by all those who receive copies directly or 
	indirectly through you, then the only way you could satisfy both it and this License would be 
	to refrain entirely from distribution of the Program.
      </para>

      <para>
	If any portion of this section is held invalid or unenforceable under any particular circumstance, 
	the balance of the section is intended to apply and the section as a whole is intended to apply 
	in other circumstances.
      </para>

      <para>
	It is not the purpose of this section to induce you to infringe any patents or other property 
	right claims or to contest validity of any such claims; this section has the sole purpose of 
	protecting the integrity of the free software distribution system, which is implemented by public 
	license practices. Many people have made generous contributions to the wide range of software 
	distributed through that system in reliance on consistent application of that system; it is up 
	to the author/donor to decide if he or she is willing to distribute software through any other 
	system and a licensee cannot impose that choice.
      </para>

      <para>
	This section is intended to make thoroughly clear what is believed to be a consequence of the 
	rest of this License.
      </para>
    </sect2>

    <sect2 id="gpl-sect8">
      <title>Section 8</title>

      <para>
	If the distribution and/or use of the Program is restricted in certain countries either by patents 
	or by copyrighted interfaces, the original copyright holder who places the Program under this License 
	may add an explicit geographical distribution limitation excluding those countries, so that 
	distribution is permitted only in or among countries not thus excluded. In such case, this License 
	incorporates the limitation as if written in the body of this License.
      </para>
    </sect2>

    <sect2 id="gpl-sect9">
      <title>Section 9</title>
      
      <para>
	The Free Software Foundation may publish revised and/or new versions of the General Public License 
	from time to time. Such new versions will be similar in spirit to the present version, but may differ 
	in detail to address new problems or concerns.
      </para>

      <para>
	Each version is given a distinguishing version number. If the Program specifies a version number of 
	this License which applies to it and "any later version", you have the option of following the terms 
	and conditions either of that version or of any later version published by the Free Software 
	Foundation. If the Program does not specify a version number of this License, you may choose any 
	version ever published by the Free Software Foundation.
      </para>
    </sect2>

    <sect2 id="gpl-sect10">
      <title>Section 10</title>

      <para>
	If you wish to incorporate parts of the Program into other free programs whose distribution 
	conditions are different, write to the author to ask for permission. For software which is copyrighted 
	by the Free Software Foundation, write to the Free Software Foundation; we sometimes make exceptions 
	for this. Our decision will be guided by the two goals of preserving the free status of all 
	derivatives of our free software and of promoting the sharing and reuse of software generally.
      </para>
    </sect2>

    <sect2 id="gpl-sect11">
      <title>NO WARRANTY</title>
      <subtitle>Section 11</subtitle>

      <para>
	BECAUSE THE PROGRAM IS LICENSED FREE OF CHARGE, THERE IS NO WARRANTY FOR THE PROGRAM, TO THE EXTENT 
	PERMITTED BY APPLICABLE LAW. EXCEPT WHEN OTHERWISE STATED IN WRITING THE COPYRIGHT HOLDERS AND/OR 
	OTHER PARTIES PROVIDE THE PROGRAM "AS IS" WITHOUT WARRANTY OF ANY KIND, EITHER EXPRESSED OR IMPLIED, 
	INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 
	PURPOSE. THE ENTIRE RISK AS TO THE QUALITY AND PERFORMANCE OF THE PROGRAM IS WITH YOU. SHOULD THE 
	PROGRAM PROVE DEFECTIVE, YOU ASSUME THE COST OF ALL NECESSARY SERVICING, REPAIR OR CORRECTION.
      </para>
    </sect2>

    <sect2 id="gpl-sect12">
      <title>Section 12</title>

      <para>
	IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING WILL ANY COPYRIGHT HOLDER, OR 
	ANY OTHER PARTY WHO MAY MODIFY AND/OR REDISTRIBUTE THE PROGRAM AS PERMITTED ABOVE, BE LIABLE TO YOU 
	FOR DAMAGES, INCLUDING ANY GENERAL, SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE 
	USE OR INABILITY TO USE THE PROGRAM (INCLUDING BUT NOT LIMITED TO LOSS OF DATA OR DATA BEING RENDERED 
	INACCURATE OR LOSSES SUSTAINED BY YOU OR THIRD PARTIES OR A FAILURE OF THE PROGRAM TO OPERATE WITH 
	ANY OTHER PROGRAMS), EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH 
	DAMAGES.
      </para>
    </sect2>
  </sect1>
</appendix>

<!--  
     The GNU Free Documentation License 1.1 in DocBook
     Markup by Eric Baudais <baudais@okstate.edu>
     Maintained by the GNOME Documentation Project
     http://developer.gnome.org/projects/gdp
     Version: 1.0.1
     Last Modified: Nov 16, 2000
-->

<appendix id="fdl">
  <appendixinfo>
    <releaseinfo>
      Version 1.1, March 2000
    </releaseinfo>
    <copyright>
      <year>2000</year><holder>Free Software Foundation, Inc.</holder>
    </copyright>
    <legalnotice id="fdl-legalnotice">
      <para>
	<address>Free Software Foundation, Inc. <street>59 Temple Place, 
        Suite 330</street>, <city>Boston</city>, <state>MA</state>  
        <postcode>02111-1307</postcode>  <country>USA</country></address> 
	Everyone is permitted to copy and distribute verbatim copies of this 
        license document, but changing it is not allowed.
      </para>
    </legalnotice>
  </appendixinfo>
  <title>GNU Free Documentation License</title>

  <sect1 id="fdl-preamble">
    <title>0. PREAMBLE</title>
    <para>
      The purpose of this License is to make a manual, textbook, or
      other written document <quote>free</quote> in the sense of
      freedom: to assure everyone the effective freedom to copy and
      redistribute it, with or without modifying it, either
      commercially or noncommercially. Secondarily, this License
      preserves for the author and publisher a way to get credit for
      their work, while not being considered responsible for
      modifications made by others.
    </para>
    
    <para>
      This License is a kind of <quote>copyleft</quote>, which means
      that derivative works of the document must themselves be free in
      the same sense. It complements the GNU General Public License,
      which is a copyleft license designed for free software.
    </para>
    
    <para>
      We have designed this License in order to use it for manuals for
      free software, because free software needs free documentation: a
      free program should come with manuals providing the same
      freedoms that the software does. But this License is not limited
      to software manuals; it can be used for any textual work,
      regardless of subject matter or whether it is published as a
      printed book. We recommend this License principally for works
      whose purpose is instruction or reference.
    </para>
  </sect1>
  <sect1 id="fdl-section1">
    <title>1. APPLICABILITY AND DEFINITIONS</title>
    <para id="fdl-document">
      This License applies to any manual or other work that contains a
      notice placed by the copyright holder saying it can be
      distributed under the terms of this License. The
      <quote>Document</quote>, below, refers to any such manual or
      work. Any member of the public is a licensee, and is addressed
      as <quote>you</quote>.
    </para>
    
    <para id="fdl-modified">
      A <quote>Modified Version</quote> of the Document means any work
      containing the Document or a portion of it, either copied
      verbatim, or with modifications and/or translated into another
      language.
    </para>
	
    <para id="fdl-secondary">
      A <quote>Secondary Section</quote> is a named appendix or a
      front-matter section of the <link
      linkend="fdl-document">Document</link> that deals exclusively
      with the relationship of the publishers or authors of the
      Document to the Document's overall subject (or to related
      matters) and contains nothing that could fall directly within
      that overall subject. (For example, if the Document is in part a
      textbook of mathematics, a Secondary Section may not explain any
      mathematics.)  The relationship could be a matter of historical
      connection with the subject or with related matters, or of
      legal, commercial, philosophical, ethical or political position
      regarding them.
    </para>

    <para id="fdl-invariant">
      The <quote>Invariant Sections</quote> are certain <link
      linkend="fdl-secondary"> Secondary Sections</link> whose titles
      are designated, as being those of Invariant Sections, in the
      notice that says that the <link
      linkend="fdl-document">Document</link> is released under this
      License.
    </para>
    
    <para id="fdl-cover-texts">
      The <quote>Cover Texts</quote> are certain short passages of
      text that are listed, as Front-Cover Texts or Back-Cover Texts,
      in the notice that says that the <link
      linkend="fdl-document">Document</link> is released under this
      License.
    </para>
	
    <para id="fdl-transparent">
      A <quote>Transparent</quote> copy of the <link
      linkend="fdl-document"> Document</link> means a machine-readable
      copy, represented in a format whose specification is available
      to the general public, whose contents can be viewed and edited
      directly and straightforwardly with generic text editors or (for
      images composed of pixels) generic paint programs or (for
      drawings) some widely available drawing editor, and that is
      suitable for input to text formatters or for automatic
      translation to a variety of formats suitable for input to text
      formatters. A copy made in an otherwise Transparent file format
      whose markup has been designed to thwart or discourage
      subsequent modification by readers is not Transparent.  A copy
      that is not <quote>Transparent</quote> is called
      <quote>Opaque</quote>.
    </para>
    
    <para>
      Examples of suitable formats for Transparent copies include
      plain ASCII without markup, Texinfo input format, LaTeX input
      format, SGML or XML using a publicly available DTD, and
      standard-conforming simple HTML designed for human
      modification. Opaque formats include PostScript, PDF,
      proprietary formats that can be read and edited only by
      proprietary word processors, SGML or XML for which the DTD
      and/or processing tools are not generally available, and the
      machine-generated HTML produced by some word processors for
      output purposes only.
    </para>
    
    <para id="fdl-title-page">
      The <quote>Title Page</quote> means, for a printed book, the
      title page itself, plus such following pages as are needed to
      hold, legibly, the material this License requires to appear in
      the title page. For works in formats which do not have any title
      page as such, <quote>Title Page</quote> means the text near the
      most prominent appearance of the work's title, preceding the
      beginning of the body of the text.
    </para>
  </sect1>
    
  <sect1 id="fdl-section2">
    <title>2. VERBATIM COPYING</title>
    <para>
      You may copy and distribute the <link
      linkend="fdl-document">Document</link> in any medium, either
      commercially or noncommercially, provided that this License, the
      copyright notices, and the license notice saying this License
      applies to the Document are reproduced in all copies, and that
      you add no other conditions whatsoever to those of this
      License. You may not use technical measures to obstruct or
      control the reading or further copying of the copies you make or
      distribute. However, you may accept compensation in exchange for
      copies. If you distribute a large enough number of copies you
      must also follow the conditions in <link
      linkend="fdl-section3">section 3</link>.
    </para>
    
    <para>
      You may also lend copies, under the same conditions stated
      above, and you may publicly display copies.
    </para>
    </sect1>
    
  <sect1 id="fdl-section3">
    <title>3. COPYING IN QUANTITY</title>
    <para>
      If you publish printed copies of the <link
      linkend="fdl-document">Document</link> numbering more than 100,
      and the Document's license notice requires <link
      linkend="fdl-cover-texts">Cover Texts</link>, you must enclose
      the copies in covers that carry, clearly and legibly, all these
      Cover Texts: Front-Cover Texts on the front cover, and
      Back-Cover Texts on the back cover. Both covers must also
      clearly and legibly identify you as the publisher of these
      copies. The front cover must present the full title with all
      words of the title equally prominent and visible. You may add
      other material on the covers in addition. Copying with changes
      limited to the covers, as long as they preserve the title of the
      <link linkend="fdl-document">Document</link> and satisfy these
      conditions, can be treated as verbatim copying in other
      respects.
    </para>
    
    <para>
      If the required texts for either cover are too voluminous to fit
      legibly, you should put the first ones listed (as many as fit
      reasonably) on the actual cover, and continue the rest onto
      adjacent pages.
    </para>
    
    <para>
      If you publish or distribute <link
      linkend="fdl-transparent">Opaque</link> copies of the <link
      linkend="fdl-document">Document</link> numbering more than 100,
      you must either include a machine-readable <link
      linkend="fdl-transparent">Transparent</link> copy along with
      each Opaque copy, or state in or with each Opaque copy a
      publicly-accessible computer-network location containing a
      complete Transparent copy of the Document, free of added
      material, which the general network-using public has access to
      download anonymously at no charge using public-standard network
      protocols. If you use the latter option, you must take
      reasonably prudent steps, when you begin distribution of Opaque
      copies in quantity, to ensure that this Transparent copy will
      remain thus accessible at the stated location until at least one
      year after the last time you distribute an Opaque copy (directly
      or through your agents or retailers) of that edition to the
      public.
    </para>
    
    <para>
      It is requested, but not required, that you contact the authors
      of the <link linkend="fdl-document">Document</link> well before
      redistributing any large number of copies, to give them a chance
      to provide you with an updated version of the Document.
    </para>
    </sect1>
    
  <sect1 id="fdl-section4">
    <title>4. MODIFICATIONS</title>
    <para>
      You may copy and distribute a <link
      linkend="fdl-modified">Modified Version</link> of the <link
      linkend="fdl-document">Document</link> under the conditions of
      sections <link linkend="fdl-section2">2</link> and <link
      linkend="fdl-section3">3</link> above, provided that you release
      the Modified Version under precisely this License, with the
      Modified Version filling the role of the Document, thus
      licensing distribution and modification of the Modified Version
      to whoever possesses a copy of it. In addition, you must do
      these things in the Modified Version:
    </para>
    
    <itemizedlist mark="opencircle">
      <listitem>
	<formalpara>
	  <title>A</title>
	  <para>
	    Use in the <link linkend="fdl-title-page">Title
	    Page</link> (and on the covers, if any) a title distinct
	    from that of the <link
	    linkend="fdl-document">Document</link>, and from those of
	    previous versions (which should, if there were any, be
	    listed in the History section of the Document). You may
	    use the same title as a previous version if the original
	    publisher of that version gives permission.
	  </para>
	</formalpara>
      </listitem>
      
      <listitem>
	<formalpara>
	  <title>B</title>
	  <para>
	    List on the <link linkend="fdl-title-page">Title
	    Page</link>, as authors, one or more persons or entities
	    responsible for authorship of the modifications in the
	    <link linkend="fdl-modified">Modified Version</link>,
	    together with at least five of the principal authors of
	    the <link linkend="fdl-document">Document</link> (all of
	    its principal authors, if it has less than five).
	  </para>
	</formalpara>
      </listitem>
      
      <listitem>
	<formalpara>
	  <title>C</title>
	  <para>
	    State on the <link linkend="fdl-title-page">Title
	    Page</link> the name of the publisher of the <link
	    linkend="fdl-modified">Modified Version</link>, as the
	    publisher.
	  </para>
	</formalpara>
      </listitem>
      
      <listitem>
	<formalpara>
	  <title>D</title>
	  <para>
	    Preserve all the copyright notices of the <link
	    linkend="fdl-document">Document</link>.
	  </para>
	</formalpara>
      </listitem>
      
      <listitem>
	<formalpara>
	  <title>E</title>
	  <para>
	    Add an appropriate copyright notice for your modifications
	    adjacent to the other copyright notices.
	  </para>
	</formalpara>
      </listitem>
      
      <listitem>
	<formalpara>
	  <title>F</title>
	  <para>
	    Include, immediately after the copyright notices, a
	    license notice giving the public permission to use the
	    <link linkend="fdl-modified">Modified Version</link> under
	    the terms of this License, in the form shown in the
	    Addendum below.
	  </para>
	</formalpara>
      </listitem>
      
      <listitem>
	<formalpara>
	  <title>G</title>
	  <para>
	    Preserve in that license notice the full lists of <link
	    linkend="fdl-invariant"> Invariant Sections</link> and
	    required <link linkend="fdl-cover-texts">Cover
	    Texts</link> given in the <link
	    linkend="fdl-document">Document's</link> license notice.
	  </para>
	</formalpara>
      </listitem>
      
      <listitem>
	<formalpara>
	  <title>H</title>
	  <para>
	    Include an unaltered copy of this License.
	  </para>
	</formalpara>
      </listitem>
      
      <listitem>
	<formalpara>
	  <title>I</title>
	  <para>
	    Preserve the section entitled <quote>History</quote>, and
	    its title, and add to it an item stating at least the
	    title, year, new authors, and publisher of the <link
	    linkend="fdl-modified">Modified Version </link>as given on
	    the <link linkend="fdl-title-page">Title Page</link>.  If
	    there is no section entitled <quote>History</quote> in the
	    <link linkend="fdl-document">Document</link>, create one
	    stating the title, year, authors, and publisher of the
	    Document as given on its Title Page, then add an item
	    describing the Modified Version as stated in the previous
	    sentence.
	  </para>
	</formalpara>
      </listitem>
      
      <listitem>
	<formalpara>
	  <title>J</title>
	  <para>
	    Preserve the network location, if any, given in the <link
	    linkend="fdl-document">Document</link> for public access
	    to a <link linkend="fdl-transparent">Transparent</link>
	    copy of the Document, and likewise the network locations
	    given in the Document for previous versions it was based
	    on. These may be placed in the <quote>History</quote>
	    section.  You may omit a network location for a work that
	    was published at least four years before the Document
	    itself, or if the original publisher of the version it
	    refers to gives permission.
	  </para>
	</formalpara>
      </listitem>
      
      <listitem>
	<formalpara>
	  <title>K</title>
	  <para>
	    In any section entitled <quote>Acknowledgements</quote> or
	    <quote>Dedications</quote>, preserve the section's title,
	    and preserve in the section all the substance and tone of
	    each of the contributor acknowledgements and/or
	    dedications given therein.
	  </para>
	</formalpara>
      </listitem>
      
      <listitem>
	<formalpara>
	  <title>L</title>
	  <para>
	    Preserve all the <link linkend="fdl-invariant">Invariant
	    Sections</link> of the <link
	    linkend="fdl-document">Document</link>, unaltered in their
	    text and in their titles.  Section numbers or the
	    equivalent are not considered part of the section titles.
	  </para>
	</formalpara>
      </listitem>
      
      <listitem>
	<formalpara>
	  <title>M</title>
	  <para>
	    Delete any section entitled
	    <quote>Endorsements</quote>. Such a section may not be
	    included in the <link linkend="fdl-modified">Modified
	    Version</link>.
	  </para>
	</formalpara>
      </listitem>
      
      <listitem>
	<formalpara>
	  <title>N</title>
	  <para>
	    Do not retitle any existing section as
	    <quote>Endorsements</quote> or to conflict in title with
	    any <link linkend="fdl-invariant">Invariant
	    Section</link>.
	  </para>
	</formalpara>
      </listitem>
    </itemizedlist>
    
    <para>
      If the <link linkend="fdl-modified">Modified Version</link>
      includes new front-matter sections or appendices that qualify as
      <link linkend="fdl-secondary">Secondary Sections</link> and
      contain no material copied from the Document, you may at your
      option designate some or all of these sections as invariant. To
      do this, add their titles to the list of <link
      linkend="fdl-invariant">Invariant Sections</link> in the
      Modified Version's license notice.  These titles must be
      distinct from any other section titles.
    </para>
    
    <para>
      You may add a section entitled <quote>Endorsements</quote>,
      provided it contains nothing but endorsements of your <link
      linkend="fdl-modified">Modified Version</link> by various
      parties--for example, statements of peer review or that the text
      has been approved by an organization as the authoritative
      definition of a standard.
    </para>
    
    <para>
      You may add a passage of up to five words as a <link
      linkend="fdl-cover-texts">Front-Cover Text</link>, and a passage
      of up to 25 words as a <link
      linkend="fdl-cover-texts">Back-Cover Text</link>, to the end of
      the list of <link linkend="fdl-cover-texts">Cover Texts</link>
      in the <link linkend="fdl-modified">Modified Version</link>.
      Only one passage of Front-Cover Text and one of Back-Cover Text
      may be added by (or through arrangements made by) any one
      entity. If the <link linkend="fdl-document">Document</link>
      already includes a cover text for the same cover, previously
      added by you or by arrangement made by the same entity you are
      acting on behalf of, you may not add another; but you may
      replace the old one, on explicit permission from the previous
      publisher that added the old one.
    </para>
    
    <para>
      The author(s) and publisher(s) of the <link
      linkend="fdl-document">Document</link> do not by this License
      give permission to use their names for publicity for or to
      assert or imply endorsement of any <link
      linkend="fdl-modified">Modified Version </link>.
    </para>
  </sect1>
    
  <sect1 id="fdl-section5">
    <title>5. COMBINING DOCUMENTS</title>
    <para>
      You may combine the <link linkend="fdl-document">Document</link>
      with other documents released under this License, under the
      terms defined in <link linkend="fdl-section4">section 4</link>
      above for modified versions, provided that you include in the
      combination all of the <link linkend="fdl-invariant">Invariant
      Sections</link> of all of the original documents, unmodified,
      and list them all as Invariant Sections of your combined work in
      its license notice.
    </para>
    
    <para>
      The combined work need only contain one copy of this License,
      and multiple identical <link linkend="fdl-invariant">Invariant
      Sections</link> may be replaced with a single copy. If there are
      multiple Invariant Sections with the same name but different
      contents, make the title of each such section unique by adding
      at the end of it, in parentheses, the name of the original
      author or publisher of that section if known, or else a unique
      number. Make the same adjustment to the section titles in the
      list of Invariant Sections in the license notice of the combined
      work.
    </para>
    
    <para>
      In the combination, you must combine any sections entitled
      <quote>History</quote> in the various original documents,
      forming one section entitled <quote>History</quote>; likewise
      combine any sections entitled <quote>Acknowledgements</quote>,
      and any sections entitled <quote>Dedications</quote>.  You must
      delete all sections entitled <quote>Endorsements.</quote>
    </para>
    </sect1>
    
  <sect1 id="fdl-section6">
    <title>6. COLLECTIONS OF DOCUMENTS</title>
    <para>
      You may make a collection consisting of the <link
      linkend="fdl-document">Document</link> and other documents
      released under this License, and replace the individual copies
      of this License in the various documents with a single copy that
      is included in the collection, provided that you follow the
      rules of this License for verbatim copying of each of the
      documents in all other respects.
    </para>
    
    <para>
      You may extract a single document from such a collection, and
      dispbibute it individually under this License, provided you
      insert a copy of this License into the extracted document, and
      follow this License in all other respects regarding verbatim
      copying of that document.
    </para>
    </sect1>
    
  <sect1 id="fdl-section7">
    <title>7. AGGREGATION WITH INDEPENDENT WORKS</title>
    <para>
      A compilation of the <link
      linkend="fdl-document">Document</link> or its derivatives with
      other separate and independent documents or works, in or on a
      volume of a storage or distribution medium, does not as a whole
      count as a <link linkend="fdl-modified">Modified Version</link>
      of the Document, provided no compilation copyright is claimed
      for the compilation.  Such a compilation is called an
      <quote>aggregate</quote>, and this License does not apply to the
      other self-contained works thus compiled with the Document , on
      account of their being thus compiled, if they are not themselves
      derivative works of the Document.  If the <link
      linkend="fdl-cover-texts">Cover Text</link> requirement of <link
      linkend="fdl-section3">section 3</link> is applicable to these
      copies of the Document, then if the Document is less than one
      quarter of the entire aggregate, the Document's Cover Texts may
      be placed on covers that surround only the Document within the
      aggregate. Otherwise they must appear on covers around the whole
      aggregate.
    </para>
    </sect1>
    
  <sect1 id="fdl-section8">
    <title>8. TRANSLATION</title>
    <para>
      Translation is considered a kind of modification, so you may
      distribute translations of the <link
      linkend="fdl-document">Document</link> under the terms of <link
      linkend="fdl-section4">section 4</link>. Replacing <link
      linkend="fdl-invariant"> Invariant Sections</link> with
      translations requires special permission from their copyright
      holders, but you may include translations of some or all
      Invariant Sections in addition to the original versions of these
      Invariant Sections. You may include a translation of this
      License provided that you also include the original English
      version of this License. In case of a disagreement between the
      translation and the original English version of this License,
      the original English version will prevail.
    </para>
    </sect1>
    
  <sect1 id="fdl-section9">
    <title>9. TERMINATION</title>
    <para>
      You may not copy, modify, sublicense, or distribute the <link
      linkend="fdl-document">Document</link> except as expressly
      provided for under this License. Any other attempt to copy,
      modify, sublicense or distribute the Document is void, and will
      automatically terminate your rights under this License. However,
      parties who have received copies, or rights, from you under this
      License will not have their licenses terminated so long as such
      parties remain in full compliance.
    </para>
    </sect1>
    
  <sect1 id="fdl-section10">
    <title>10. FUTURE REVISIONS OF THIS LICENSE</title>
    <para>
      The <ulink type="http"
      url="http://www.gnu.org/fsf/fsf.html">Free Software
      Foundation</ulink> may publish new, revised versions of the GNU
      Free Documentation License from time to time. Such new versions
      will be similar in spirit to the present version, but may differ
      in detail to address new problems or concerns. See <ulink
      type="http"
      url="http://www.gnu.org/copyleft">http://www.gnu.org/copyleft/</ulink>.
    </para>
    
    <para>
      Each version of the License is given a distinguishing version
      number. If the <link linkend="fdl-document">Document</link>
      specifies that a particular numbered version of this License
      <quote>or any later version</quote> applies to it, you have the
      option of following the terms and conditions either of that
      specified version or of any later version that has been
      published (not as a draft) by the Free Software Foundation. If
      the Document does not specify a version number of this License,
      you may choose any version ever published (not as a draft) by
      the Free Software Foundation.
    </para>
  </sect1>

  <sect1 id="fdl-using">
    <title>Addendum</title>
    <para>
      To use this License in a document you have written, include a copy of
      the License in the document and put the following copyright and
      license notices just after the title page:
    </para>
    
    <blockquote>
      <para>
	Copyright &copy; YEAR YOUR NAME.
      </para>
      <para>
	Permission is granted to copy, distribute and/or modify this
	document under the terms of the GNU Free Documentation
	License, Version 1.1 or any later version published by the
	Free Software Foundation; with the <link
	linkend="fdl-invariant">Invariant Sections</link> being LIST
	THEIR TITLES, with the <link
	linkend="fdl-cover-texts">Front-Cover Texts</link> being LIST,
	and with the <link linkend="fdl-cover-texts">Back-Cover
	Texts</link> being LIST.  A copy of the license is included in
	the section entitled <quote>GNU Free Documentation
	License</quote>.
      </para>
    </blockquote>
      
    <para>
      If you have no <link linkend="fdl-invariant">Invariant
      Sections</link>, write <quote>with no Invariant Sections</quote>
      instead of saying which ones are invariant.  If you have no
      <link linkend="fdl-cover-texts">Front-Cover Texts</link>, write
      <quote>no Front-Cover Texts</quote> instead of
      <quote>Front-Cover Texts being LIST</quote>; likewise for <link
      linkend="fdl-cover-texts">Back-Cover Texts</link>.
    </para>
    
    <para>
      If your document contains nontrivial examples of program code,
      we recommend releasing these examples in parallel under your
      choice of free software license, such as the <ulink type="http"
      url="http://www.gnu.org/copyleft/gpl.html"> GNU General Public
      License</ulink>, to permit their use in free software.
    </para>
  </sect1>
</appendix>  

</Part>

</Book>
