CONTROL.CTL(5) InterNetNews Documentation CONTROL.CTL(5)
NAME
control.ctl - Specify handling of Usenet control messages
DESCRIPTION
The file pathetc/control.ctl is used to determine what action is taken
when a control message is received. It is read by controlchan, which
is normally invoked as a channel program by innd. When control.ctl is
modified, controlchan notices this automatically and reloads it.
If a control.ctl.local file exists in pathetc, it is read by
controlchan after control.ctl (the resulting behaviour is as though the
contents of control.ctl.local were at the end of control.ctl). This
local file is formatted like control.ctl and is intended to contain
local customization. It is also automatically reloaded when modified.
Blank lines and lines beginning with a number sign ("#") are ignored.
All other lines should consist of four fields separated by colons:
<type>:<from>:<newsgroups>:<action>
Lines are matched in order and the last matching line in the file will
be used, except for checkgroups messages which are handled differently
(every matching line is used).
The first field, <type>, is the type of control message for which this
line is valid. It should either be the name of a control message or
the word "all" to indicate that it applies to all control messages.
Besides, the following special types are understood:
/encoding/
This type specifies the encoding of newgroup and checkgroups
control messages so that new descriptions could be decoded the
right way.
/encoding/:*:cn.*:gb18030
means that a description for a newsgroup in the Chinese cn.*
hierarchy will be decoded as though it were encoded in GB18030,
unless a charset is specified in the control message (in such a
case, the charset mentioned in the message is used). However, it
is possible to override the mentioned charset if "=force" is
appended after the encoding. For instance,
/encoding/:*:scout.forum.chinese:big5=force
means that the description for scout.forum.chinese will always be
decoded as though it were encoded in Big5, no matter the charset of
the corresponding control message.
The default value when no encoding is mentioned (or when the
specified encoding is unknown) is "CP1252".
The last matching line for a given newsgroup name in control.ctl
will be used.
/localencoding/
When this type is used, the line consist of only two fields. The
default value when this type does not appear in control.ctl (or
when the specified charset is unknown) is equivalent to:
/localencoding/:utf-8
It means that new descriptions in the newsgroups file will be
written using UTF-8. And controlchan will try to read existing
descriptions, so as to see whether they should be updated, as
though they were encoded in UTF-8.
The last matching line in control.ctl will be used.
/maxdocheckgroups/
This type specifies the maximum number of changes that could be
made at one time by a checkgroups before bailing and mailing the
changes to the admin if no log file was specified. The default
value is 10.
/maxdocheckgroups/:*:*:10
/maxdocheckgroups/:*:fr.*:20
Such a configuration means that a checkgroups containing 15 changes
for the French fr.* hierarchy (newgroups to add, remove or change
the status) will be automatically honoured whereas a checkgroups
containing 15 changes for france.* will only have the required
changes mailed or logged.
The last matching line for a given newsgroup name in control.ctl
will be used.
The second field, <from>, is a shell-style pattern that matches the
e-mail address of the person posting the message (with the address
first converted to lowercase). The matching is done with rules
equivalent to those of the shell's case statement; see sh(1) for more
details.
If the control message is a newgroup or rmgroup, the third field,
<newsgroups>, is a shell-style pattern matching the newsgroup affected
by the control message (especially "?" matches exactly one character,
"*" matches zero or more characters and "|" permits matching several
patterns on the same line -- for instance "comp.*|humanities.*"
matches every newsgroup whose name begins with "comp." or
"humanities."). If the control message is a checkgroups, the third
field is a shell-style pattern matching the newsgroups that should be
processed for checking. If the control message is of any other type,
the third field is ignored.
The fourth field, <action>, specifies what action to take with control
messages that match this line. The following actions are understood:
doit
The action requested by the control message should be performed.
It means that the change will be silently performed. For
checkgroups messages, depending on the value of /maxdocheckgroups/,
the shell commands that should be run may be mailed to the news
administrator (the argument to --with-news-master given at
configure time, "usenet" by default) instead of being performed.
If you always want notification of actions taken, use "doit=mail"
instead (see below).
doifarg
If the control message has an argument, this is equivalent to doit.
If it does not have an argument, this is equivalent to mail. This
is only useful for entries for sendsys control messages, allowing a
site to request its own newsfeeds entry by posting a "sendsys
mysite" control message, but not allowing the entire newsfeeds file
to be sent. This was intended to partially counter so-called
"sendsys bombs", where forged sendsys control messages were used to
mailbomb people.
Processing sendsys control messages is not recommended even with
this work-around unless they are authenticated in some fashion.
The risk of having news servers turned into anonymous mail bombing
services is too high.
doit=file
The action is performed as in doit, and additionally a log entry is
written to the specified log file file. If file is the word
"mail", the log entry is mailed to the news administrator instead.
An empty string is equivalent to /dev/null and says to log nothing.
If file starts with a slash, it is taken as the absolute filename
to use for the log file. Otherwise, the filename is formed by
prepending pathlog and a slash, and appending ".log". In other
words, an action of "doit=newgroup" will log to
pathlog/newgroup.log.
drop
No action is taken and the message is ignored. For checkgroups
messages, it means that the newsgroups mentioned will be considered
as not existent in the checkgroups for its subsequent process.
checkgroups:*:comp.*:doit
checkgroups:*:*binaries*:drop
will for instance remove every newsgroup whose name contains
"binaries" in the comp.* hierarchy, even though such groups are
mentioned in the checkgroups. (In that example, the removal is
performed by the doit action because drop does nothing by itself.)
verify-*
If the action starts with the string "verify-", as in:
verify-news.announce.newgroups
then PGP verification of the control message will be done and the
user ID of the key of the authenticated signer will be checked
against the expected identity defined by the rest of the string
("news.announce.newgroups" in the above example). This
verification is done via pgpverify; see pgpverify(8) for more
details.
If no logging is specified (with =file as mentioned below), logging
will be done the same as with doit as described above.
verify-*=mail
PGP verification is done as for the verify-* action described
above, and notification of successful newgroup and rmgroup control
messages and the output of checkgroups messages will be mailed to
the news administrator. (In the case of checkgroups messages, this
means that the shell script that should be run will be mailed to
the administrator. The subject of the mail will contain
information on whether the script has already been run, depending
on the value of /maxdocheckgroups/.)
verify-*=file
PGP verification is done as for the verify-* action described
above, and a log entry is written to the specified file as
described in doit=file above. (In the case of checkgroups
messages, this means that the shell script output of the
checkgroups message will be written to that file. The initial line
of the log will contain information on whether the script has
already been run, depending on the value of /maxdocheckgroups/.)
log A one-line log message is sent to standard error. innd normally
directs this to pathlog/errlog.
log=file
A log entry is written to the specified log file, which is
interpreted as in doit=file described above.
mail
A mail message is sent to the news administrator without taking any
other action.
One of the difference between a doit or verify action and a mail action
for a checkgroups control message lies in what e-mail is sent; doit or
verify will mail the news administrator a shell script (which may have
already been run) to create, delete, or modify newsgroups to match the
checkgroups message, whereas mail will just mail relevant lines of the
checkgroups for manual processing by the news administrator.
Use of the verify action for processing newgroup, rmgroup and
checkgroups messages is STRONGLY recommended. Abuse of control
messages is rampant, and authentication via PGP signature is currently
the only reliable way to be sure that a control message comes from who
it claims to be from. Most major hierarchies are now issuing PGP-
authenticated control messages.
In order to use verify actions, the PGP key ring of the news user must
be populated with the PGP keys of the hierarchy maintainers whose
control messages you want to honour. For more details on PGP-
authenticated control messages and the URL for downloading the PGP keys
of major hierarchies, see pgpverify(8).
Control messages of type cancel are handled internally by innd and
cannot be affected by any of the mechanisms described here.
EXAMPLES
With the following three lines in control.ctl:
newgroup:*:*:drop
newgroup:group-admin@isc.org:comp.*:verify-news.announce.newgroups
newgroup:kre@munnari.oz.au:aus.*:mail
a newgroup coming from "group-admin@isc.org" will be honoured if it is
for a newsgroup in the comp.* hierarchy and if it has a valid signature
corresponding to the PGP key with a user ID of
"news.announce.newgroups". If any newgroup claiming to be from
"kre@munnari.oz.au" for a newsgroup in the aus.* hierarchy is received,
it too will be honoured. All other newgroup messages will be ignored.
Besides, if a control.ctl.local file exists and contains:
newgroup:*:comp.lang.*:drop
then a newgroup control article for comp.lang.awk will not be honoured
even though it comes from "group-admin@isc.org" with a valid signature.
As for checkgroups, suppose your news server contains these groups for
foo.*, all of them being unmoderated ("y" status in the active file):
foo.bar1
foo.bar2.first
foo.bar2.second
foo.bar2.third
foo.bar3
foo.bar3.first
foo.bar3.second
foo.bar5
and you receive the following checkgroups by <foo@bar.com> for foo.*:
foo.bar1 A valid newsgroup.
foo.bar3.first Only one newsgroup in foo.bar3.*.
foo.bar4 A newsgroup you want.
foo.bar5 A newsgroup you do not want.
foo.bar5.first Another newsgroup you do not want.
with the following control.ctl entries:
/maxdocheckgroups/:*:foo.*:2
checkgroups:foo@bar.com:foo.*:verify-key-foo
checkgroups:foo@bar.com:foo.bar2.*:doit
checkgroups:foo@bar.com:foo.bar3.*:mail
checkgroups:foo@bar.com:foo.bar4|foo.bar4.*:doit
checkgroups:foo@bar.com:foo.bar5|foo.bar5.*:drop
Then, as control.ctl is processed from bottom, here is what happens:
1. The newsgroups foo.bar5 and foo.bar5.first are marked as unwanted.
But nothing is done yet: other control.ctl entries have to be
processed with a real action and a set of newsgroups containing
foo.bar5 and foo.bar5.first.
2. The newsgroup foo.bar4 is silently created on the news server, with
the description "A newsgroup you want." added to the newsgroups
file. In the absence of encoding values (either in the checkgroups
message or in /encoding/ and /localencoding), the default is to
decode the sentence as CP1242 and re-encode it as UTF-8.
If "doit=mail" was used, a mail would be sent to the news
administrator to inform him that foo.bar4 was successfully created.
3. The newsgroup foo.bar3.second is no longer present. A mail is sent
to the news administrator with a shell script to execute. When it
is manually executed, foo.bar3.second will be removed.
Note that the descriptions are handled differently and have already
been updated without any manual intervention (foo.bar3.first now
has the description "Only one newsgroup in foo.bar3.*." and
foo.bar3.second no longer has a description).
4. The newsgroups foo.bar2.first, foo.bar2.second and foo.bar2.third
are no longer present. However, as the maximum number of changes
that could be made at one time by a checkgroups before bailing and
mailing the changes to the news administrator is 2, these
newsgroups are not removed. A mail is sent with a shell script to
manually execute in order to remove these groups from the news
server.
Note that their descriptions are removed from the newsgroups file,
as well as any other possible descriptions for obsolete newsgroups
in foo.bar2.*.
5. The remaining entry is executed if the PGP verification of the
checkgroups message is successful. Otherwise, nothing is done
(especially, foo.bar5 remains on the news server).
In case the PGP signature is verified, foo.bar3 and foo.bar5 are
removed from the news server. This entry acts upon newsgroups
marked as dropped in its scope and newsgroups not already dealt
with by previous control.ctl entries (like foo.bar3 because only
foo.bar3.* was previously checked).
Note that if you had wanted to keep foo.bar3 or foo.bar5, you could
have added them to the localgroups file in pathetc.
HISTORY
Written by Rich $alz <rsalz@uunet.uu.net> for InterNetNews. Rewritten
in POD by Russ Allbery <eagle@eyrie.org>.
$Id: control.ctl.pod 10283 2018-05-14 12:43:05Z iulius $
SEE ALSO
controlchan(8), inn.conf(5), innd(8), newsfeeds(5), newsgroups(5),
pgpverify(8), sh(1).
INN 2.6.4 2018-05-15 CONTROL.CTL(5)