=head1 NAME

nnrpd - NNTP server for reader clients

=head1 SYNOPSIS

B<nnrpd> [B<-DfnoSt>] [B<-b> I<address>] [B<-c> I<configfile>]
[B<-g> I<shadowgroup>>] [B<-i> I<initial>] [B<-I> I<instance>] [B<-p> I<port>]
[B<-P> I<prefork>] [B<-r> I<reason>] [B<-s> I<padding>]

=head1 DESCRIPTION

B<nnrpd> is an NNTP server for newsreaders.  It accepts commands on its
standard input and responds on its standard output.  It is normally
invoked by innd(8) with those descriptors attached to a remote client
connection.  B<nnrpd> also supports running as a standalone daemon.

Unlike innd(8) B<nnrpd> supports all NNTP commands for user-oriented
reading and posting.  B<nnrpd> uses the F<readers.conf> file to control
who is authorized to access the Usenet database.

On exit, B<nnrpd> will report usage statistics through syslog(3).

B<nnrpd> only reads config files (both F<readers.conf> and F<inn.conf>)
when it is spawned.  You can therefore never change the behavior of a
client that's already connected.  If B<nnrpd> is run from B<innd> (the
default) or from inetd(8), xinetd(8), or some equivalent, a new B<nnrpd>
process is spawned for every connection and therefore any changes to
configuration files will be immediately effective for all new
connections.  If you are instead running B<nnrpd> with the B<-D> option,
any configuration changes won't take effect until B<nnrpd> is restarted.

The F<inn.conf> setting I<nnrpdflags> can be used to pass any of the
options below to instances of B<nnrpd> that are spawned directly from
B<innd>.  Many options only make sense when B<-D> is used, so these
options should not be used with I<nnrpdflags>.  See also the discussion
of I<nnrpdflags> in inn.conf(5).

When I<nnrpdloadlimit> in F<inn.conf> is not 0, it will also reject
connections if the load average is greater than that value (typically 16).
B<nnrpd> can also prevent high-volume posters from abusing your
resources. See the discussion of exponential backoff in inn.conf(5).

=head1 OPTIONS

=over 4

=item B<-b> I<address>

The B<-b> parameter instructs B<nnrpd> to bind to the specified IP
address when started as a standalone daemon using the B<-D> flag. This
has to be a valid IPv4 or IPv6 address belonging to an interface of
the local host.  It can also be ::0 (although the default is 0.0.0.0
if unspecified).

=item B<-c> I<configfile>

By default, B<nnrpd> reads the F<readers.conf> to determine how to
authenticate connections.  The B<-c> flag specifies an alternate file
for this purpose.  If the file name isn't fully qualified, it is taken
to be relative to I<pathetc> in F<inn.conf> (this is useful to have
several instances of B<nnrpd> running on different ports or IP
addresses with different settings.)

=item B<-D>

If specified, this parameter causes B<nnrpd> to operate as a
daemon. That is, it detaches itself and runs in the background,
forking a process for every connection. By default B<nnrpd> listens on
the NNTP port (119), so either innd(8) has to be started on another
port or B<nnrpd> B<-p> parameter.  Note that with this parameter,
B<nnrpd> continues running until killed.  This means that it reads
F<inn.conf> once on startup and never again until restarted. B<nnrpd>
should therefore be restarted if inn.conf is changed.

When started in daemon mode, B<nnrpd> will write its PID into a file in
the I<pathrun> directory.  The file will be named F<nnrpd-%d.pid>, where
C<%d> is replaced with the port that B<nnrpd> is configured to listen on
(119 unless the B<-p> option is given).

=item B<-f>

If specified, B<nnrpd> does not detach itself and runs in the
foreground when started as a standalone daemon using the B<-D> flag.

=item B<-g> I<shadowgroup>

On systems that have a shadow password file, B<nnrpd> tries to add the
group I<shadow> as a supplementary group if it is running in
standalone mode. On many systems, members of that group have read
permission for the shadow password file. The B<-g> parameter instructs
B<nnrpd> to try to add the named group as a supplementary group on
shadow systems instead of I<shadow>. This only works if
C<HAVE_GETSPNAM> in F<include/config.h> is defined and B<nnrpd> is
running in standalone mode since this call only works when B<nnrpd> is
started as root.

=item B<-i> I<initial>

Specify an initial command to B<nnrpd>. When used, I<initial> is taken
as if it were the first command received by B<nnrpd>.

=item B<-I> I<instance>

If specified I<instance> is used as an additional static portion
within MessageIDs generated by B<nnrpd>; typically this option would
be used where a cluster of machines exist with the same virtual
hostname and must be disambiguated during posts.

=item B<-n>

The B<-n> flag turns off resolution of IP addresses to names.  If you
only use IP-based restrictions in F<readers.conf> and can handle IP
addresses in your logs, using this flag may result in some additional
speed.

=item B<-o>

The B<-o> flag causes all articles to be spooled instead of sending
them to innd(8). B<rnews> with the B<-U> flag should be invoked from
cron on a regular basis to take care of these articles. This flag is
useful if innd(8) in accepting articles and B<nnrpd> is started
standalone or using inetd(8).

=item B<-p> I<port>

The B<-p> parameter instructs B<nnrpd> to listen on I<port> when
started as a standalone daemon using the B<-D> flag.

=item B<-P> I<prefork>

The B<-P> parameter instructs B<nnrpd> to prefork I<prefork> children
awaiting connections when started as a standalone daemon using the
B<-D> flag.

=item B<-r> I<reason>

If the B<-r> flag is used, then B<nnrpd> will reject the incoming
connection giving I<reason> as the text. This flag is used by innd(8)
when it is paused or throttled.

=item B<-s> I<padding>

As each command is received, B<nnrpd> tries to change its C<argv>
array so that ps(1) will print out the command being executed. To get
a full display, the B<-s> flag may be used with a long string as its
argument, which will be overwritten when the program changes its
title.

=item B<-S>

If specified, B<nnrpd> will start a negotiation for SSL session as
soon as connected. To use this flag, C<--with-openssl> must have been
specified at C<configure> time.

=item B<-t>

If the B<-t> flag is used then all client commands and initial
responses will be traced by reporting them in syslog. This flag is set
by innd(8) under the control of the ctlinnd(8) C<trace> command, and
is toggled upon receipt of a C<SIGHUP>; see signal(2).

=back

=head1 SSL SUPPORT

If INN is built with C<--with-openssl>, B<nnrpd> will support news reading
over TLS (also known as SSL).  For clients that use the STARTTLS command,
no special configuration is needed beyond creating a TLS/SSL certificate
for the server.  You should do this in exactly the same way that you would
generate a certificate for a web server.

If you're happy with a self-signed certificate (which will generate
warnings with some news reader clients), you can create and install one in
the default path by running C<make cert> after C<make install> when
installing INN, or by running the following commands:

    openssl req -new -x509 -nodes -out /usr/local/news/lib/cert.pem \
        -days 366 -keyout /usr/local/news/lib/key.pem
    chown news:news /usr/local/news/lib/cert.pem
    chmod 640 /usr/local/news/lib/cert.pem
    chown news:news /usr/local/news/lib/key.pem
    chmod 600 /usr/local/news/lib/key.pem

Replace the paths with something appropriate to your INN installation.
This will create a self-signed certificate that will expire in a year.
The B<openssl> program will ask you a variety of questions about your
organization.  Enter the fully qualified domain name of the server as the
name the certificate is for.

Most news clients currently do not use the STARTTLS command, however, and
instead expect to connect to a separate port (563) and start an SSL
negotiation immediately.  B<innd> does not, however, know how to listen
for connections to that port and then spawn B<nnrpd> the way that it does
for regular reader connections.  You will therefore need to arrange for
B<nnrpd> to listen on that port through some other means.  This can be
done with the B<-D> flag (and C<-P 563>), but the easiest way is probably
to add a line like:

    nntps stream tcp nowait news /usr/lib/news/bin/nnrpd nnrpd -S

to F</etc/inetd.conf> or the equivalent on your system and let B<inetd>
run B<nnrpd>.  (Change the path to B<nnrpd> to match your installation if
needed.)  You may need to replace C<nntps> with C<563> if C<nntps> isn't
defined in F</etc/services> on your system.

=head1 PROTOCOL DIFFERENCES

B<nnrpd> implements the NNTP commands defined in RFC 977, with the
following differences:

=over 4

=item 1.

The C<slave> command is not implemented.  This command has never been
fully defined.

=item 2.

The C<list> command may be followed by the optional word C<active.times>,
C<distributions>, C<distrib.pats>, C<moderators>, C<newsgroups>,
C<subscriptions>, or C<Ioverview.fmt> to get a list of when newsgroups
where created, a list of valid distributions, a file specifying default
distribution patterns, moderators list, a one-per-line description of the
current set of newsgroups, a list of the automatic group subscriptions, or
a listing of the F<overview.fmt> file.

The command C<list active> is equivalent to the C<list> command. This
is a common extension.

=item 3.

The C<xhdr>, C<authinfo user> and C<authinfo pass> commands are
implemented.  These are based on the reference Unix implementation.  See
RFC 2980.

=item 4.

A new command, C<xpat header range|MessageID pat [morepat...]>, is
provided.  The first argument is the case-insensitive name of the header
to be searched.  The second argument is either an article range or a
single Message-ID, as specified in RFC 977.  The third argument is a
C<uwildmat>(3)-style pattern; if there are additional arguments they are
joined together separated by a single space to form the complete pattern.
This command is similar to the C<xhdr> command.  It returns a C<221>
response code, followed by the text response of all article numbers that
match the pattern.

=item 5.

The C<listgroup group> command is provided.  This is a comment extension.
It is equivalent to the C<group> command, except that the reply is a
multi-line response containing the list of all article numbers in the
group.

=item 6.

The C<xgtitle [group]> command is provided. This extension is used by
ANU-News.  It returns a C<282> reply code, followed by a one-line
description of all newsgroups thatmatch the pattern.  The default is the
current group.

=item 7.

The C<xover [range]> command is provided. It returns a C<224> reply code,
followed by the overview data for the specified range; the default is to
return the data for the current article.

=item 8.

The C<xpath MessageID> command is provided; see innd(8).

=item 9.

The C<date> command is provided; this is based on the draft NNTP protocol
revision (draft-ietf-nntpext-imp-04.txt).  It returns a one-line response
code of C<111> followed by the GMT date and time on the server in the form
C<YYYYMMDDhhmmss>.

=back

=head1 HISTORY

Written by Rich $alz <rsalz@uunet.uu.net> for InterNetNews.  Overview
support added by Rob Robertston <rob@violet.berkeley.edu> and Rich in
January, 1993.  Exponential backoff (for posting) added by Dave Hayes in
Febuary 1998.

$Id: nnrpd.pod 7751 2008-04-06 14:35:40Z iulius $

=head1 SEE ALSO

ctlinnd(8), innd(8), inn.conf(5), signal(2), uwildmat(3).