INND(8)

NAME
innd - InterNetNews daemon

SYNOPSIS
innd [-adfNrsSu] [-4 address] [-6 address] [-c days] [-H count] [-i count] [-l size] [-m mode] [-n flag] [-o count] [-P port] [-t timeout] [-T count] [-X seconds]

DESCRIPTION
innd, the InterNetNews daemon, handles all incoming NNTP feeds, coordinates the storage, retransmission, and overview generation for all accepted articles, and manages the active(5) and history(5) databases. It handles incoming connections on the NNTP port, and also creates and listens to a local Unix-domain stream socket in order to receive articles from local processes such as nnrpd(8) and rnews(1).

As the master daemon, innd should generally be started at boot and be always running. It listens to a Unix-domain datagram socket for commands to control its activities, commands that can be sent using ctlinnd(8). The current status of innd can be obtained by running "ctlinnd mode", or for more detailed output, innstat(8).

innd can be in one of three operating modes: running, paused, or throttled. Running is the normal mode; when the server is throttled, it closes connections and rejects new ones. Paused is like a temporary throttle, suspending innd's activities but not causing the server to shut down existing connections. The mode is normally changed via ctlinnd(8), either by various automated processes (such as nightly article expiration) or manually by the news administrator, but innd will also throttle itself if it encounters ENOSPC errors in writing data or an excessive number of I/O errors (among other problems).

innd normally takes care of spawning nnrpd(8) to handle connections from news reading clients, but it can be run on a separate port from nnrpd(8) so that feed connections and news reading connections are handled separately (this can often be faster). Normally, innd listens on port 119, the assigned port for NNTP; if it is desirable to run innd and nnrpd(8) on separate ports, it's recommended that nnrpd(8) be given port 119 (since many news reading clients connect only to that port) and that port 433 be used for innd.

The primary configuration files that control innd's activities are incoming.conf, which specifies what remote sites innd will accept connections from, newsfeeds, which specifies what is to be done with incoming articles besides storing them, and inn.conf, which sets a wide variety of configuration parameters. Some parameters in inn.conf(5) can also be set with command-line flags; for these, the command-line flags take precedence if used.

innd must be run as the news user and news group. It will check for this at startup and fail to start if not run properly. Normally it should be started via rc.news(8) as part of the system boot up process. It relies on the setuid root helper program innbind(8) to listen on a privileged port (119, 433 or 563).

OPTIONS
For the options below that override inn.conf settings, see inn.conf(5) for the default values if neither the inn.conf setting nor the command-line option is given.

-4 address
    Normally, innd binds to all local IP addresses (unless bindaddress is set in inn.conf). If this option is given, it specifies the IP address that INN should bind as. This is only relevant for servers with multiple local IP addresses. The IP address must be in dotted-quad ("nnn.nnn.nnn.nnn") format.

    If this option is specified, it's the same as setting bindaddress in inn.conf and may cause changes in whether INN binds to an IPv6 address as well. See inn.conf(5) for more details and also the -6 flag for innd.

    This option has no effect when systemd socket activation is used.

-6 address
    Only applies when INN has been built with IPv6 support. Normally innd binds to all local IP addresses (unless bindaddress6 is set in inn.conf). If this option is given, it specifies the IPv6 address that INN should bind to. The IPv6 address must be in colon-separated RFC 4291 format ("n:n:n:n:n:n:n:n").

    If this option is specified, it's the same as setting bindaddress6 in inn.conf and may cause changes in whether INN binds to an IPv4 address as well. See inn.conf(5) for more details and also the -4 flag for innd.

    This option has no effect when systemd socket activation is used.

-a  By default, if a host connects to innd but is not listed in incoming.conf, the connection is handed off to nnrpd (or rejected if noreader is set in inn.conf). If -a is given, incoming.conf is ignored and any host can connect and transfer articles. This flag should never be used with an accessible server connected to Usenet; it would open the server up for all sorts of abuse.

-c days
    innd normally rejects any article that is older (in days) than the value of artcutoff in inn.conf. This option, if given, overrides the value of that setting. If days is 0, this check is suppressed and innd will accept articles regardless of how old they are.

    Note that rejected articles are remembered during the number of days specified by the "/remember/" line in expire.ctl(5). You'll have to wait that number of days before being able to inject again an article with the same previously rejected Message-ID.

    In case you need re-injecting articles before that amount of time, you'll have to set "/remember/" to 0 in expire.ctl, run the expire process (for instance via news.daily called with the same parameters as in crontab, plus "notdaily") and undo the change in expire.ctl. All previously rejected or removed articles will then not be considered as duplicate if their Message-ID is proposed.

-d, -f
    innd normally puts itself into the background, points its standard output and error to log files, and disassociates itself from the terminal. Using -d prevents all of this, resulting in log messages being written to standard output; this is generally useful only for debugging. Using -f prevents the backgrounding and disassociation but still redirects output; it may be useful if you want to monitor innd with a program that would be confused by forks.

-H count, -T count, -X seconds
    These flags control the number of connections per seconds seconds that are allowed. This code is meant to protect your server from newsreader clients that make too many connections per minute (and therefore these flags are probably only useful when innd is spawning nnrpd). You probably should not use these options unless you're having problems. The table used for this check is fixed at 128 entries and is used as a ring; the size was chosen to make calculating the index easy and to be fairly sure that it won't run out of space. In practice, it is unlikely that even half the table will be used at any given moment.

    The -H flag limits the number of times a host is allowed to connect to the server per the time interval given by -X. The default is 2.

    The -T flag limits the total number of incoming connections per the time interval given by -X. The maximum value is 128, and the default is 60.

    Note that the time interval given by -X is set to 0 by default, that is to say no control is done on the number of connections.

-i count
    innd normally allows a maximum number of concurrent NNTP connections given by the value of maxconnections in inn.conf. This option, if given, overrides the value of that setting. If count is 0, this check is suppressed.

-l size
    innd normally rejects any article larger than the value of maxartsize in inn.conf. This option, if given, overrides the value of that setting and specifies a maximum article size of size. If size is 0, this check is suppressed.

-m mode
    Normally, innd starts in the "running" mode. If this option is given, it specifies what mode innd should start in. mode should begin with one of "g", "p", or "t", and the starting mode will be set to "running", "paused", or "throttled", respectively, based on that initial letter. ("g" is short for "go".)

-N  If this option is given, any filters (Perl or Python) are disabled before innd starts (normally, filters default to being enabled). The filters can be enabled after innd has started with ctlinnd(8).

-n flag
    Whether innd allows (and hands off to nnrpd) reader connections while paused or throttled is normally determined by the value of readerswhenstopped in inn.conf. This option, if given, overrides that value. If flag is "n", innd will not allow readers if it is paused or throttled. If flag is "y", readers will be allowed regardless of innd's operating mode.

-o count
    This flag limits the number of file descriptors that are available for outgoing file feeds. The default is the number of available file descriptors minus some reserved for internal use (which could potentially starve innd of descriptors to use for accepting new connections). If innd has more file feeds than count, some of them will be buffered and only written out periodically.

    Normally you never need to use this option, since the number of outgoing feeds is fixed, being the number of file feeds configured in newsfeeds, and is generally small (particularly given that innfeed(8) is now used for most outgoing feeds at large sites).

-P port
    The port innd should listen on is normally given by the value of port in inn.conf. This option, if given, overrides that value and specifies the port that innd should bind to.

-r  Instructs innd to renumber the active file after starting, just as if a "ctlinnd renumber" command were sent.

-s  Just check the syntax of the newsfeeds file and exit. innd will exit with a non-zero status if any errors are found; the actual errors will be reported via syslog(3).

-S  Report errors found in incoming.conf via syslog(3) and exit normally. (Yes, this is less useful than it should be.)

-t seconds
    Normally, innd will flush any changes to history and the active file after 300 seconds of inactivity. This option changes that timeout to seconds.

-u  The news log (the trace information for every article accepted by innd) is normally buffered. This option changes the log to be unbuffered.

CONTROL MESSAGES
Arriving articles that have a Control header field are called "control messages". Except for cancel messages, these messages are handled by controlchan(8) via a feed set up in newsfeeds.

(Cancel messages update the history database, so they must be handled internally; the cost of syncing, locking, then unlocking would be too high given the number of cancel messages that are received. Note that if an article is cancelled before it is received by the news server, it will be rejected when it arrives since the history database has been updated; it is useful for rejecting spam before it arrives.)

The distribution of control messages is different than that of standard articles. Control messages are normally filed into the pseudo-newsgroup named "control" regardless of which newsgroup they were actually posted to. If, however, a "control."command newsgroup exists that matches the control command, the control message will be filed into that group instead. For example, a newgroup control message will be filed in "control.newgroup" if that group exists; otherwise, it will be filed in "control".

If you want to specifically feed all control messages to a given site regardless of whether the control messages would affect the newsgroups you're feeding that site, you can put the appropriate control newsgroup in the subscription list. For example, to feed all cancel messages to a given remote site (normally a bad idea), add "control.cancel" to its subscription list. Normally it's best to exclude the control newsgroups from feeds to keep from sending your peers more control messages than they care about. That's why the newsfeeds pattern "!control,!control.*" is as often as not specified (adding this pattern do not prevent control messages which affect the newsgroups fed to a site from being sent to it).

checkgroups, newgroup and rmgroup control messages receive additional special treatment. If one of these control messages is approved and posted to the newsgroup being created or removed (or to the admin group to which the checkgroups is posted), the message will be sent to all sites whose subscription patterns would cause them to receive articles posted to that group. For example, if a newgroup control message for a nonexistent newsgroup "news.admin.meow" is received, it will be sent to any site whose subscription pattern would cause it to receive "news.admin.meow" if that newsgroup existed (such as a pattern of "news.admin.*"). For this reason, it is correct to post newgroup messages to the newsgroup that the control message would create. It is not generally correct to crosspost newgroup messages to some "well-propagated" newsgroup; not only will this not actually improve their propagation to sites that want such control messages, but it will also cause sites that do not want those control messages to receive them. Therefore, assuming that a newgroup control message is sent to the group "news.admin.meow" (specified in the Newsgroups header field body) in order to create the group "news.admin.meow", the sites with the following subscription patterns will receive it:

    *,@news.*
    news.*
    news.*,!control,!control.*
    control,control.*

As a matter of fact, for the first pattern, "control.newgroup" (or "control") is included in "*". However, the sites with the following subscription patterns will not receive it:

    *,@news.*,!control,!control.*
    comp.*,@news.*

If a control message is posted to a group whose name ends with the four characters ".ctl", this suffix is stripped off and the control message is propagated as if it were posted to the base group. For example, a cancel message posted to "news.admin.ctl" will be sent to all sites that subscribe to "control.cancel" (or "control" if that newsgroup doesn't exist) or "news.admin". This behavior is present for historical compatibility reasons and should be considered obsolete; support for the ".ctl" suffix may be removed in a future version of INN.

Finally, articles posted to newsgroups beginning with "to." are treated specially. Provided that either that newsgroup exists in the active file or mergetogroups is set in inn.conf, the remainder of the newsgroup is taken to be a site name, as configured in newsfeeds, and the article is sent to sites propagating "to.uunet". If mergetogroups is set, the article will be filed in the group named "to" (which must exist in the active file). For example, with mergetogroups set, an article posted to "to.uunet" will be filed in "to" and sent to the sites propagating "to.uunet".

PROTOCOL DIFFERENCES
innd implements the NNTP commands defined in RFC 3977 (NNTP), RFC 4643 (NNTP authentication), RFC 4644 (streaming NNTP feeds) and RFC 6048 (NNTP LIST additions) with the following differences:

1.  A batch transfer command, XBATCH byte-count, is provided. This command will read byte-count bytes and store them for later processing by rnews(1) (which must be run separately, probably from cron). See innxbatch(8) and sendxbatches for more details on this extension.

2.  As INN is a mode-switching news server, innd implements a limited subset of the protocol useful for transferring news. The remaining commands are mostly only useful for readers and are implemented by nnrpd(8). Use of the MODE READER command will cause innd to pass the connection to nnrpd.

3.  innd allows a wider syntax for wildmats.

4.  Three commands (IHAVE, CHECK and TAKETHIS) will continue, for interoperability reasons, to return a reject code (respectively 435, 438 and 439) when the command contains a syntax error (which normally leads to 501).

HEADER MODIFICATIONS
innd modifies as few article headers as possible, although it could be better in this area.

Empty header field bodies and header field bodies that consist of nothing but whitespace are dropped.

The local site's name (as set with the pathhost parameter in inn.conf) and an exclamation point are prepended to the Path header field body, provided the first site name in the Path header field body is different from the local one. In addition, pathalias and pathcluster may be similarly respectively prepended and appended as path identities immediately to the right or the left of pathhost in the Path header field body; see inn.conf(5) for the details.

The Xref header field is removed and a new one created.

innd does not rewrite incorrect header fields. For example, it will not replace an incorrect Lines header field, though it may reject such an article depending on the value of linecountfuzz in inn.conf.

CANCEL FEEDS
In order to efficiently apply a large number of local cancels (such as from processing NoCeMs or from some other external source), INN supports a special feed mode available only to connections to the local Unix-domain socket (not to connections to any network sockets).

To enter this mode, connect to the Unix-domain socket (pathrun/nntpin) and send the command MODE CANCEL. The response will have code 284. Every subsequent line sent on that connection should consist of a single message-ID. An attempt will be made to cancel that message-ID, and the server will reply 289 for success or 484 for failure. (Failure can occur, for example, if the server is paused or throttled, or the message-ID is corrupt. Failure does not occur if the article to be cancelled does not exist.)

LOGGING
innd reports all incoming articles in its log file (pathlog/news). This is a text file with a variable number of space-separated fields in one of the following formats:

    mon dd hh:mm:ss.mmm + feed <message-id> site ...
    mon dd hh:mm:ss.mmm j feed <message-id> site ...
    mon dd hh:mm:ss.mmm c feed <message-id> Cancelling <message-id>
    mon dd hh:mm:ss.mmm - feed <message-id> reason
    mon dd hh:mm:ss.mmm ? feed <message-id> reason

There may also be hostname and/or size fields after the message-ID depending on the settings of nntplinklog and logartsize in inn.conf.

The first three fields are the date and time to millisecond resolution. The fifth field is the site that sent the article (based on the Path header field body) and the sixth field is the article's Message-ID; they will be a question mark if the information is not available.

The fourth field indicates whether the article was accepted or not. If it is a plus sign, then the article was accepted. If it is the letter "j", then the article was accepted, providing all of the newsgroups to which the article was posted were set to status "j" in the active file (or not listed in the active file and wanttrash was set in inn.conf), and then the article was filed into the "junk" newsgroup. In both of these cases, the article has been accepted and the "site ..." field contains the space-separated list of sites to which the article is being sent.

If the fourth field is the letter "c", then a cancel message was accepted before the original article arrived, and a history entry for the cancelled message was created so that innd will reject that message if it arrives later.

If the fourth field is a minus sign, then the article was rejected. The reasons for rejection generated by innd include:

    "%s" header too long
    Article exceeds local limit of %s bytes
    Article posted in the future -- "%s"
    Bad "%s" header field
    Can't write history
    Duplicate
    Duplicate "%s" header field
    EOF in headers
    Linecount %s != %s +- %s
    Missing %s header field
    No body
    No colon-space in "%s" header field
    No matching newsgroups in cancel <%s>
    No space
    Space before colon in "%s" header field
    Too old -- "%s"
    Unapproved for "%s"
    Unwanted newsgroup "%s"
    Unwanted distribution "%s"
    Whitespace in "Newsgroups" header field -- "%s"

where %s, above, is replaced by more specific information. (The Perl and Python filters, if used, may reject articles with other reasons.)

If the fourth field is the letter "?", the article contains strange strings, such as CR without LF or LF without CR. (These characters should never occur in isolation, only together as CRLF to indicate the end of a line.) This log message is just informational, to give an idea of how widespread such articles are; innd does not reject such articles.

Note that when wanttrash is set to true in inn.conf and an article is received that isn't posted to any valid newsgroups, it will be accepted and logged with two lines, a "j" line and a minus sign line, unless the logtrash parameter is set to false (in which case only the "j" line is written).

innd also makes extensive reports through syslog(3). The first word of the log message will be the name of the site if the entry is site-specific (such as a "connected" message). The first word will be "SERVER" if the message relates to the server itself, such as when a read error occurs.

If the second word is the four letters "cant", then an error is being reported. (The absence of an apostrophe is intentional; it makes it easier to grep from the command line and easier to find error messages in FAQs using a search engine. However, "can't" is also used at a few places.) In this case, the next two words generally name the system call or library routine that failed and the object upon which the action was being performed. The rest of the line may contain other information.

In other cases, the second word attempts to summarize what change has been made, while the rest of the line gives more specific information. The word "internal" generally indicates an internal logic error.

SIGNALS
innd will catch SIGTERM and SIGHUP and shut down. If -d is used, SIGINT will also be caught and will result in an orderly shutdown.

innd will catch the SIGUSR1 signal and recreate the control channel used by ctlinnd(8).

BUGS
innd normally attempts to strip IP options from incoming connections, since it uses IP-based authentication and source routing can confuse that. However, this doesn't work on all systems, and it doesn't work at all in the presence of IPv6 support (and is disabled in that case). Hence, if using innd with IPv6 support, make sure that your kernel or router disables source routing.

HISTORY
Written by Rich $alz <rsalz@uunet.uu.net> for InterNetNews.

SEE ALSO
active(5), ctlinnd(8), history(5), incoming.conf(5), inn.conf(5), innbind(8), innfeed(8), innstat(8), libinn_dbz(3), libinn_inndcomm(3), newsfeeds(5), nnrpd(8), rnews(1), syslog(3).