NNRPD(8) InterNetNews Documentation NNRPD(8)
NAME
nnrpd - NNTP server for reader clients
SYNOPSIS
nnrpd [-BDfnoSt] [-4 address] [-6 address] [-b address] [-c configfile]
[-i initial] [-I instance] [-p port] [-P prefork] [-r reason] [-s
padding]
DESCRIPTION
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. nnrpd also supports running as a standalone daemon.
Unlike innd(8), nnrpd supports all NNTP commands for user-oriented
reading and posting. nnrpd uses the readers.conf file to control who
is authorized to access the Usenet database.
On exit, nnrpd will report usage statistics through syslog(3).
nnrpd is run from innd (the default) or from inetd(8), xinetd(8), or
some equivalent. As often as not, it is also run as a daemon, with the
-D option, to provide TLS support on a dedicated port.
nnrpd only reads config files (readers.conf, inn.conf and
inn-secrets.conf) when it is spawned. You can therefore never change
the behaviour of a client that's already connected. As a new nnrpd
process is spawned for every connection, any changes to these
configuration files will be immediately effective for all new
connections. There's only one exception: when nnrpd is run as a daemon
with the -D option, any configuration changes in inn.conf won't take
effect until nnrpd is restarted.
The inn.conf setting nnrpdflags can be used to pass any of the options
below to instances of nnrpd that are spawned directly from innd. Many
options only make sense when -D is used, so these options should not be
used with nnrpdflags. See also the discussion of nnrpdflags in
inn.conf(5).
When nnrpdloadlimit in inn.conf is not 0, it will also reject
connections if the load average is greater than that value (typically
16). nnrpd can also prevent high-volume posters from abusing your
resources. See the discussion of exponential backoff in inn.conf(5).
nnrpd injects articles into the local server running innd through a
UNIX domain socket, or an INET domain socket if not supported. If
another server should be used for injection, you can set it with the
nnrpdposthost parameter in inn.conf. In case authentication
credentials are requested during the injection, nnrpd will use the
passwd.nntp file in pathetc.
OPTIONS
-4 address
The -4 parameter instructs nnrpd to bind to the specified IPv4
address when started as a standalone daemon using the -D flag.
This has to be a valid IPv4 address belonging to an interface of
the local host. It can also be 0.0.0.0, saying to bind to all
addresses (this is the default).
-6 address
The -6 parameter instructs nnrpd to bind to the specified IPv6
address when started as a standalone daemon using the -D flag.
This has to be a valid IPv6 address belonging to an interface of
the local host. It can also be "::0", saying to bind to all IPv6
addresses.
By default, nnrpd in daemon mode listens to both IPv4 and IPv6
addresses. With this option, it will listen only to the specified
IPv6 addresses. On some systems however, a value of "::0" will
cause it to listen to all IPv4 addresses as well.
-b address
Similar to the -4 flag. -b is kept for backwards compatibility.
-B If specified, nnrpd will report login attempts to blocklistd(8) for
automatic blocking after a number of failed attempts. To use this
flag, the blocklist library must have been found at configure time,
or --with-blocklist specified at configure time. For more
information, see "BLACKLISTD SUPPORT" below.
-c configfile
By default, nnrpd reads the readers.conf configuration file to
determine how to authenticate connections. The -c flag specifies
an alternate file for this purpose. If the file name isn't fully
qualified, it is taken to be relative to pathetc in inn.conf.
(This is useful to have several instances of nnrpd running on
different ports or IP addresses with different settings.)
-D If specified, this parameter causes nnrpd to operate as a daemon.
That is, it detaches itself and runs in the background, forking a
process for every connection. By default, nnrpd listens on the
NNTP port (119), so either innd(8) has to be started on another
port or the -p parameter used. Note that with this parameter,
nnrpd continues running until killed. This means that it reads
inn.conf once on startup and never again until restarted. nnrpd
should therefore be restarted if inn.conf is changed.
When started in daemon mode, nnrpd will write its PID into a file
in the pathrun directory. The file will be named nnrpd.pid if
nnrpd listens on port 119 (default), or nnrpd-%d.pid, where %d is
replaced with the port that nnrpd is configured to listen on (-p
option is given and its argument is not 119).
You may also want to use -s when running nnrpd as a daemon.
-f If specified, nnrpd does not detach itself and runs in the
foreground when started as a standalone daemon using the -D flag.
-i initial
Specify an initial command to nnrpd. When used, initial is taken
as if it were the first command received by nnrpd. After having
responded, nnrpd will close the connection.
-I instance
If specified, instance is used as an additional static portion
within Message-IDs generated by nnrpd, when virtualhost is set in
access groups in readers.conf; typically this option would be used
where a cluster of machines exist with the same virtual hostname
and must be disambiguated during posts.
-n The -n flag turns off resolution of IP addresses to names. If you
only use IP-based restrictions in readers.conf and can handle IP
addresses in your logs, using this flag may result in some
additional speed.
-o The -o flag causes all articles to be spooled instead of sending
them to innd(8). rnews with the -U flag should be invoked from
cron on a regular basis to take care of these articles. This flag
is useful if innd is accepting articles and nnrpd is started
standalone or using inetd(8).
-p port
The -p parameter instructs nnrpd to listen on port when started as
a standalone daemon using the -D flag.
-P prefork
The -P parameter instructs nnrpd to prefork prefork children
awaiting connections when started as a standalone daemon using the
-D flag.
-r reason
If the -r flag is used, then nnrpd will reject the incoming
connection giving reason as the text. This flag is used by innd(8)
when it is paused or throttled. reason should be encoded in UTF-8.
-s padding
As each command is received from a client, nnrpd tries to change
its "argv" array containing the process title so that commands like
ps(1) will print out the hostname of the connected client and the
command being executed. To get a full display, the -s flag may be
used with a long string as its argument, which will be overwritten
when nnrpd changes its title.
When innd spawns nnrpd, this flag is used with an argument made of
48 spaces.
-S If specified, nnrpd will start a negotiation for a TLS session as
soon as connected. To use this flag, the OpenSSL SSL and crypto
libraries must have been found at configure time, or --with-openssl
specified at configure time. For more information on running nnrpd
with TLS support, see "TLS SUPPORT".
-t If the -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) "trace" command,
and is toggled upon receipt of a SIGHUP; see signal(2).
TLS SUPPORT
If INN is built with --with-openssl or if the OpenSSL SSL and crypto
libraries are found at configure time, 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 "make cert" after "make install" when
installing INN, or by running the following commands:
umask 077
openssl req -new -x509 -nodes -out <pathetc>/cert.pem \
-days 366 -keyout <pathetc>/key.pem
chown news:news <pathetc>/cert.pem
chmod 640 <pathetc>/cert.pem
chown news:news <pathetc>/key.pem
chmod 600 <pathetc>/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 openssl program will ask you a variety of questions about your
organization. Enter the fully qualified domain name of your news
service (either the server canonical name or a dedicated alias for the
news service) as the name the certificate is for.
You then have to set these inn.conf parameters with the right paths:
tlscapath: <pathetc>
tlscertfile: <pathetc>/cert.pem
tlskeyfile: <pathetc>/key.pem
If you want to use a complete certificate chain, you can directly put
it in tlscertfile (like Apache's SSLCertificateFile directive).
Alternately, you can put a single certificate in tlscertfile and use
tlscafile for additional certificates needed to complete the chain,
like a separate authority root certificate.
More concretely, when using Let's Encrypt certificates, Certbot's files
can be installed as follows:
tlscapath: /etc/letsencrypt/live/news.server.com
tlscertfile: /etc/letsencrypt/live/news.server.com/fullchain.pem
tlskeyfile: /etc/letsencrypt/live/news.server.com/privkey.pem
or:
tlscapath: /etc/letsencrypt/live/news.server.com
tlscafile: /etc/letsencrypt/live/news.server.com/chain.pem
tlscertfile: /etc/letsencrypt/live/news.server.com/cert.pem
tlskeyfile: /etc/letsencrypt/live/news.server.com/privkey.pem
Make sure that the permission rights are properly set so that the news
user or the news group can read these directories and files (typically,
he should access /etc/letsencrypt/live/news.server.com and
/etc/letsencrypt/archive/news.server.com where the real keys are
located, and the private key should not be world-readable).
There are two common ways for a news client to negotiate a TLS
connection: either via the use of a dedicated port (usually 563) on
which TLS is immediately negotiated upon connection, or via the now
discouraged way (per RFC 8143) to use the STARTTLS command on the usual
NNTP port (119) to dynamically upgrade from unencrypted to TLS-
protected traffic during an NNTP session. innd does not, however, know
how to listen for connections to that separate port (563). You will
therefore need to arrange for nnrpd to listen on that port through some
other means. This can be done with the -D flag along with "-p 563" and
put into your init scripts:
su news -s /bin/sh -c '<pathbin>/nnrpd -D -p 563 -S'
but the easiest way is probably to add a line like:
nntps stream tcp nowait news <pathbin>/nnrpd nnrpd -S
to /etc/inetd.conf or the equivalent on your system and let inetd run
nnrpd. (Change the path to nnrpd to match your installation.) You may
need to replace "nntps" with 563 if "nntps" isn't defined in
/etc/services on your system. You may also want to use the lowercase
-s flag with a long string as its argument to see more information
about incoming connections in ps(1) output.
Optionally, you may set the tlsciphers, tlsciphers13, tlscompression,
tlseccurve, tlspreferserverciphers, and tlsprotocols parameters in
inn.conf to fine-tune the behaviour of the TLS/SSL negotiation whenever
a new attack on the TLS protocol or some supported cipher suite is
discovered.
BLACKLISTD SUPPORT
blocklistd(8) is a FreeBSD/NetBSD daemon for preventing brute force
attacks by blocking attackers after a number of failed login attempts.
When nnrpd is built with blocklistd support, it will report login
attempts to the blocklistd daemon for potential blocking.
Adding the configuration below to /etc/blocklistd.conf under the
"[local]" section, assuming nnrpd is listening on port 563, would lead
to attackers being blocked for 10 minutes after 5 failed login
attempts.
# adr/mask:port type proto owner name nfail disable
563 stream * * * 5 10m
See the blocklistd(8) documentation for more information.
PROTOCOL DIFFERENCES
nnrpd implements the NNTP commands defined in RFC 3977 (NNTP), RFC 4642
updated by RFC 8143 (TLS/NNTP), RFC 4643 (NNTP authentication),
RFC 6048 (NNTP LIST additions) and RFC 8054 (NNTP compression) with the
following differences:
1. The XGTITLE [wildmat] command is provided. This extension is used
by ANU-News and documented in RFC 2980. It returns a 282 reply
code, followed by a one-line description of all newsgroups that
match the pattern. The default is the current group.
Note that LIST NEWSGROUPS should be used instead of XGTITLE.
2. The XHDR header [message-ID|range] command is implemented. It
returns a 221 reply code, followed by specific header fields for
the specified range; the default is to return the data for the
current article. See RFC 2980.
Note that HDR should be used instead of XHDR.
3. The XOVER [range] command is provided. It returns a 224 reply
code, followed by the overview data for the specified range; the
default is to return the data for the current article. See
RFC 2980.
Note that OVER should be used instead of XOVER.
4. A new command, XPAT header message-ID|range pattern [pattern ...],
is provided. The first argument is the case-insensitive name of
the header field to be searched. The second argument is either an
article range or a single message-ID, as specified in RFC 2980.
The third argument is a uwildmat-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 XHDR command. It returns a 221 response code, followed by
the text response of all article numbers that match the pattern.
5. A newsgroup name is case-sensitive for nnrpd.
6. If IHAVE has been advertised, it will not necessarily be advertised
for the entire session (contrary to section 3.4.1 of RFC 3977).
nnrpd only advertises the IHAVE capability when it is really
available.
7. nnrpd allows a wider syntax for wildmats and ranges (especially "-"
and "-article-number").
8. When keyword generation is used, an experimental feature enabled
with the keywords parameter in inn.conf, "Keywords:full" is
advertised in LIST OVERVIEW.FMT even though overview information is
computed and does not necessarily come from Keywords header fields.
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.
SEE ALSO
blocklistd(8), ctlinnd(8), innd(8), inn.conf(5), inn-secrets.conf(5),
libinn_uwildmat(3), nnrpd.track(5), passwd.nntp(5), readers.conf(5),
signal(2).
INN 2.7.1 2023-04-16 NNRPD(8)
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