NEWSFEEDS (5)
NAME
newsfeeds - determine where Usenet articles get sent
DESCRIPTION
The file <config$_PATH_NEWSFEEDS> (typically /var/news/etc/newsfeeds
specifies how incoming articles should be distributed to other sites. It
is parsed by the InterNetNews server innd(8) when it starts up, or when
directed to by ctlinnd(8) .
The file is interpreted as a set of lines according to the following
rules. If a line ends with a backslash, then the backslash, the newline,
and any whitespace at the start of the next line is deleted. This is
repeated until the entire ``logical'' line is collected. If the logical
line is blank, or starts with a number sign (``#''), it is ignored.
All other lines are interpreted as feed entries. An entry should consist
of four colon-separated fields; two of the fields may have optional sub-
fields, marked off by a slash. Fields or sub-fields that take multiple
parameters should be separated by a comma. Extra whitespace can cause
problems. Except for the site names, case is significant. The format of
an entry is:
sitename[/exclude,exclude,...]\
:pattern,pattern...[/distrib,distrib...]\
:flag,flag...\
:param
Each field is described below.
The sitename is the name of the site to which a news article can be sent.
It is used for writing log entries and for determining if an article
should be forwarded to a site. If sitename already appears in the
article's Path header, then the article will not be sent to the site.
The name is usually whatever the remote site uses to identify itself in
the Path line, but can be almost any word that makes sense; special local
entries (such as archivers or gateways) should probably end with an
exclamation point to make sure that they do not have the same name as any
real site. For example, ``gateway'' is an obvious name for the local
entry that forwards articles out to a mailing list. If a site with the
name ``gateway'' posts an article, when the local site receives the
article it will see the name in the Path and not send the article to its
own ``gateway'' entry. See also the description of the ``Ap'' flag,
below. If an entry has an exclusion sub-field, then the article will not
be sent to that site if any of the names specified as excludes appear in
the Path header. The same sitename can be used more than once -- the
appropriate action will be taken for each entry that should receive the
article, regardless of the name -- although this is recommended only for
program feeds to avoid confusion. Case is not significant in site names.
The patterns specify which groups to send to the site and are interpreted
to build a ``subscription list'' for the site. The default subscription
is to get all groups. The patterns in the field are wildmat(3) -style
patterns, and are matched in order against the list of newsgroups that
the local site receives. If the first character of a pattern is an
exclamation mark, then any groups matching the pattern are removed from
the subscription, otherwise any matching groups are added. For example,
to receive all ``comp'' groups, but only comp.sources.unix within the
sources newsgroups, the following set of patterns can be used:
comp.*,!comp.sources.*,comp.sources.unix
There are three things to note about this example. The first is that the
trailing ``.*'' is required. The second is that, again, the result of
the last match is the most important. The third is that
``comp.sources.*'' could be written as ``comp.sources*'' but this would
not have the same effect if there were a ``comp.sources-only'' group.
There is also a way to subscribe to a newsgroup negatively. That is to
say, do not send this group even if the article is cross-posted to a
subscribed newsgroup. If the first character of a pattern is an atsign
``@'', it means that any article posted to a group matching the pattern
will not be sent even though the article may be cross-posted to a group
which is subscribed. The same rules of precedence apply in that the last
match is the one which counts. For example, if you want to prevent all
articles posted to any "alt.binaries.warez" group from being propagated
even if it is cross-posted to another "alt" group or any other group for
that matter, then the following set of patterns can be used:
alt.*,@alt.binaries.warez.*,misc.*
If you reverse the alt.* and alt.binaries.warez.* patterns, it would
nullify the atsign because the result of the last match is the one that
counts. Using the above example, if an article is posted to one or more
of the alt.binaries.warez.* groups and is cross-posted to misc.test, then
the article is not sent.
See innd(8) for details on the propagation of control messages.
A subscription can be further modified by specifying ``distributions''
that the site should or should not receive. The default is to send all
articles to all sites that subscribe to any of the groups where it has
been posted , but if an article has a Distribution header and any
distribs are specified, then they are checked according to the following
rules:
1. If the Distribution header matches any of the values in the sub-
field, then the article is sent.
2. If a distrib starts with an exclamation point, and it matches the
Distribution header, then the article is not sent.
3. If Distribution header does not match any distrib in the site's
entry, and no negations were used, then the article is not sent.
4. If Distribution header does not match any distrib in the site's
entry, and any distrib started with an exclamation point, then the
article is sent.
If an article has more than one distribution specified, then each one is
according to the above rules. If any of the specified distributions
indicate that the article should be sent, it is; if none do, it is not
sent -- the rules are used as a ``logical or.'' It is almost definitely
a mistake to have a single feed that specifies distributions that start
with an exclamation point along with some that don't.
Distributions are text words, not patterns; entries like ``*'' or ``all''
have no special meaning.
The flags parameter specifies miscellaneous parameters. They may be
specified in any order; flags that take values should have the value
immediately after the flag letter with no whitespace. The valid flags
are:
<size
An article will only be sent to the site if it is less than size
bytes long. The default is no limit.
>size
An article will only be sent to the site if it is greater than size
bytes long. The default is no limit.
Achecks
An article will only be sent to the site if it meets the
requirements specified in the checks, which should be chosen from
the following set:
d Distribution header required
p Do not check Path header for the sitename before
propagating (the exclusions are still checked).
Bhigh/low
If a site is being fed by a file, channel, or exploder (see below),
the server will normally start trying to write the information as
soon as possible. Providing a buffer may give better system
performance and help smooth out overall load if a large batch of
news comes in. The value of the this flag should be two numbers
separated by a slash. The first specifies the point at which the
server can start draining the feed's I/O buffer, and the second
specifies when to stop writing and begin buffering again; the units
are bytes. The default is to do no buffering, sending output as
soon as it is possible to do so.
Fname
This flag specifies the name of the file that should be used if it
is necessary to begin spooling for the site (see below). If name is
not an absolute pathname, it is taken to be relative to
<config$_PATH_BATCHDIR> (typically /var/news/spool/out.going.)
Then, if the destination is a directory, the file togo in that
directory will be used as filename.
Gcount
If this flag is specified, an article will only be sent to the site
if it is posted to no more than count newsgroups.
Hcount
If this flag is specified, an article will only be sent to the site
if it has count or fewer sites in its Path line. This flag should
only be used as a rough guide because of the loose interpretation of
the Path header; some sites put the poster's name in the header, and
some sites that might logically be considered to be one hop become
two because they put the posting workstation's name in the header.
The default value for count is one.
Isize
The flag specifies the size of the internal buffer for a file feed.
If there are more file feeds then allowed by the system, they will
be buffered internally in least-recently-used order. If the
internal buffer grows bigger then size bytes, however, the data will
be written out to the appropriate file. The default value is
<config$SITE_BUFFER_SIZE> bytes (typically (16 * 1024 ) .)
Nmodifiers
The newsgroups that a site receives are modified according to the
modifiers, which should be chosen from the following set:
m Only moderated groups
u Only unmoderated groups
Ssize
If the amount of data queued for the site gets to be larger than
size bytes, then the server will switch to spooling, appending to a
file specified by the ``F'' flag, or <config$_PATH_BATCHDIR>/
sitename (typically /var/news/spool/out.going/ sitename) if the
``F'' flag is not specified. Spooling usually happens only for
channel or exploder feeds.
Ttype
This flag specifies the type of feed for the site. Type should be a
letter chosen from the following set:
c Channel
f File
l Log entry only
m Funnel (multiple entries feed into one)
p Program
x Exploder
Each feed is described below in the section on feed types. The
default is Tf.
Witems
If a site is fed by file, channel, or exploder, this flag controls
what information is written. If a site is fed by a program, only
the asterisk (``*'') has any effect. The items should be chosen
from the following set:
b Size of the article in bytes
f Article's full pathname
g The newsgroup the article is in;
if cross-posted, then the first of the groups this
site gets
m Article's Message-ID
n Article's pathname relative to the spool directory
p The time the article was posted as seconds since epoch.
s The site that fed the article to the server;
from the Path header, when <config$IPADDR_LOG> is DONT,
otherwise the IP address.
t Time article was received as seconds since epoch
* Names of the appropriate funnel entries;
or all sites that get the article
D Value of the Distribution header;
? if none present
H All headers
N Value of the Newsgroups header
O Overview data
R Information needed for replication
More than one letter can be used; the entries will be separated by a
space, and written in the order in which they are specified. The
default is Wn.
The ``H'' and ``O'' items are intended for use by programs that
create news overview databases. If ``H'' is present, then the all
the article's headers are written followed by a blank line. An Xref
header (even if one does not appear in the filed article) and a
Bytes header, specifying the article's size, will also be part of
the headers. If used, this should be the only item in the list; if
preceeded by other items, however, a newline will be written before
the headers. The ``O'' generates input to the overchan(8) program.
It, too, should be the only item in the list.
The asterisk has special meaning. It expands to a space-separated
list of all sites that received the current article. If the site is
the target of a funnel however (i.e., it is named by other sites
which have a ``Tm'' flag), then the asterisk expands to the names of
the funnel feeds that received the article. If the site is fed by a
program, then an asterisk in the param field will be expanded into
the list of funnel feeds that received the article. A site fed by a
program cannot get the site list unless it is the target of other
``Tm'' feeds.
The interpretation of the param field depends on the type of feed, and is
explained in more detail below in the section on feed types. It can be
omitted.
The site named ME is special. There should only be one such entry, and
it should be the first entry in the file. If the ME entry has a
subscription list, then that list is automatically prepended to the
subscription list of all other entries. For example,
``*,!control,!junk,!foo.*'' can be used to set up the initial
subscription list for all feeds so that local postings are not propagated
unless ``foo.* explicitly appears in the site's subscription list. Note
that most subscriptions should have ``!junk,!control'' in their pattern
list; see the discussion of ``control messages'' in innd(8) . (Unlike
other news software, it does not affect what groups are received; that is
done by the active(5) file.)
If the ME entry has a distribution subfield, then only articles that
match the distribution list are accepted; all other articles are
rejected. A commercial news server, for example, might have ``/!local''
to reject local postings from other, misconfigured, sites.
FEED TYPES
Innd provides four basic types of feeds: log, file, program, and channel.
An exploder is a special type of channel. In addition, several entries
can feed into the same feed; these are funnel feeds, that refer to an
entry that is one of the other types. Note that the term ``feed'' is
technically a misnomer, since the server does not transfer articles, but
reports that an article should be sent to the site.
The simplest feed is one that is fed by a log entry. Other than a
mention in the news logfile, no data is ever written out. This is
equivalent to a ``Tf'' entry writing to /dev/null except that no file is
opened.
A site fed by a file is simplest type of feed. When the site should
receive an article, one line is written to the file named by the param
field. If param is not an absolute pathname, it is taken to be relative
to <config$_PATH_BATCHDIR> (typically /var/news/spool/out.going.) If
empty, the filename defaults to <config$_PATH_BATCHDIR>/sitename
(typically /var/news/spool/out.going/sitename.) This name should be
unique.
When a site fed by a file is flushed (see ctlinnd), the following steps
are performed. The script doing the flush should have first renamed the
file. The server tries to write out any buffered data, and then closes
the file. The renamed file is now available for use. The server will
then re-open the original file, which will now get created.
A site fed by a program has a process spawned for every article that the
site receives. The param field must be a sprintf(3) format string that
may have a single %s parameter, which will be given a pathname for the
article, relative to the news spool directory. The full path name may be
obtained by prefixing the %s in the param field by the news spool
directory prefix. Standard input will be set to the article or /dev/null
if the article cannot be opened for some reason. Standard output and
error will be set to the error log. The process will run with the user
and group ID of the <config$_PATH_INNDDIR> directory (typically .
/var/news/run.) Innd will try to avoid spawning a shell if the command
has no shell meta-characters; this feature can be defeated by appending a
semi-colon to the end of the command. The full pathname of the program
to be run must be specified; for security, PATH is not searched.
If the entry is the target of a funnel, and if the ``W*'' flag is used,
then a single asterisk may be used in the param field where it will be
replaced by the names of the sites that fed into the funnel. If the
entry is not a funnel, or if the ``W*'' flag is not used, then the
asterisk has no special meaning.
Flushing a site fed by a program does no action.
When a site is fed by a channel or exploder, the param field names the
process to start. Again, the full pathname of the process must be given.
When the site is to receive an article, the process receives a line on
its standard input telling it about the article. Standard output and
error, and the user and group ID of the all sub-process are set as for a
program feed, above. If the process exits, it will be restarted. If the
process cannot be started, the server will spool input to a file named
<config$_PATH_BATCHDIR>/sitename (typically
/var/news/spool/out.going/sitename.) It will then try to start the
process some time later.
When a site fed by a channel or exploder is flushed, the server closes
down its end of the pipe. Any pending data that has not been written
will be spooled; see the description of the ``S'' flag, above. No signal
is sent; it is up to the program to notice EOF on its standard input and
exit. The server then starts a new process.
Exploders are a superset of channel feeds. In addition to channel
behavior, exploders can be sent command lines. These lines start with an
exclamation point, and their interpretation is up to the exploder. The
following messages are generated automatically by the server:
newgroup group
rmgroup group
flush
flush site
These messages are sent when the ctlinnd command of the same name is
received by the server. In addition, the ``send'' command can be used to
send an arbitrary command line to the exploder child-process. The
primary exploder is buffchan(8) .
Funnel feeds provide a way of merging several site entries into a single
output stream. For a site feeding into a funnel, the param field names
the actual entry that does the feeding.
For more details on setting up different types of news feeds, see the INN
installation manual.
EXAMPLES
## Initial subscription list and our distributions.
ME:*,!junk,!foo.*/world,usa,na,ne,foo,ddn,gnu,inet\
::
## Feed all moderated source postings to an archiver
source-archive!:!*,*sources*,!*wanted*,!*.d\
:Tc,Wn:<config$_PATH_NEWSBIN>/archive -f -i \
/usr/spool/news.archive/INDEX
## Watch for big postings
watcher!:*\
:Tc,Wbnm\
:exec awk '$1 > 1000000 { print "BIG", $2, $3 }' >/dev/console
## A UUCP feed, where we try to keep the "batching" between 4 and
1K.
ihnp4:/world,usa,na,ddn,gnu\
:Tf,Wnb,B4096/1024:
## Usenet as mail; note ! in funnel name to avoid Path conflicts.
## Can't use ! in "fred" since it would like look a UUCP address.
fred:!*,comp.sources.unix,comp.sources.bugs\
:Tm:mailer!
barney@bar.com:!*,news.software.nntp,comp.sources.bugs\
:Tm:mailer!
mailer!:!*\
:W*,Tp:/usr/ucb/Mail -s "News article" *
## NNTP feeds fed off-line via nntpsend or equivalent.
feed1::Tf,Wnm:feed1.domain.name
peer.foo.com:foo.*:Tf,Wnm:peer.foo.com
## Real-time transmission.
mit.edu:/world,usa,na,ne,ddn,gnu,inet\
:Tc,Wnm:<config$_PATH_NEWSBIN>/nntplink -i stdin mit.edu
## Two sites feeding into a hypothetical NNTP fan-out program:
nic.near.net:\
:Tm:nntpfunnel1
uunet.uu.net/uunet:!ne.*/world,usa,na,foo,ddn,gnu,inet\
:Tm:nntpfunnel1
nntpfunnel1:!*\
:Tc,Wmn*:<config$_PATH_NEWSBIN>/nntpfanout
## A UUCP site that wants comp.* and moderated soc groups
uucpsite!comp:!*,comp.*/world,usa,na,gnu\
:Tm:uucpsite
uucpsite!soc:!*,soc.*/world,usa,na,gnu\
:Tm,Nm:uucpsite
uucpsite:!*\
:Tf,Wnb:/usr/spool/batch/uucpsite
The last two sets of entries show how funnel feeds can be used. For
example, the nntpfanout program would receive lines like the following on
its standard input:
<123@litchi.foo.com> comp/sources/unix/888 nic.near.net uunet.uu.net
<124@litchi.foo.com> ne/general/1003 nic.near.net
Since the UUCP funnel is only destined for one site, the asterisk is not
needed and entries like the following will be written into the file:
<qwe#37x@snark.uu.net> comp/society/folklore/3
<123@litchi.foo.com> comp/sources/unix/888
HISTORY
Written by Rich $alz <rsalz@uunet.uu.net> for InterNetNews. This is
revision 1.35, dated 1996/12/17.
SEE ALSO
active(5) , buffchan(8) , ctlinnd(8) , innd(8) , wildmat(3) .
You can find a summary and links related to this topic
as part of the Mib Software Usenet RKT.