Provided by: mosquitto_1.4.8-1build1_amd64 bug

NAME

       mosquitto - an MQTT broker

SYNOPSIS

       mosquitto [-c config file] [-d | --daemon] [-p port number] [-v]

DESCRIPTION

       mosquitto is a broker for the MQTT protocol version 3.1.

OPTIONS

       -c, --config-file
           Load configuration from a file. If not given, the default values as described in
           mosquitto.conf(5) are used.

       -d, --daemon
           Run mosquitto in the background as a daemon. All other behaviour remains the same.

       -p, --port
           Listen on the port specified instead of the default 1883. This acts in addition to the
           port setting in the config file. May be specified multiple times to open multiple
           sockets listening on different ports. This socket will be bound to all network
           interfaces.

       -v, --verbose
           Use verbose logging. This is equivalent to setting log_type to all in the
           configuration file. This overrides and logging options given in the configuration
           file.

CONFIGURATION

       The broker can be configured using a configuration file as described in mosquitto.conf(5)
       and this is the main point of information for mosquitto. The files required for SSL/TLS
       support are described in mosquitto-tls(7).

BROKER STATUS

       Clients can find information about the broker by subscribing to topics in the $SYS
       hierarchy as follows. Topics marked as static are only sent once per client on
       subscription. All other topics are updated every sys_interval seconds. If sys_interval is
       0, then updates are not sent.

       Note that if you are using a command line client to interact with the $SYS topics and your
       shell interprets $ as an environment variable, you need to place the topic in single
       quotes '$SYS/...' or to escape the dollar symbol: \$SYS/... otherwise the $SYS will be
       treated as an environment variable.

       $SYS/broker/bytes/received
           The total number of bytes received since the broker started.

       $SYS/broker/bytes/sent
           The total number of bytes sent since the broker started.

       $SYS/broker/clients/connected, $SYS/broker/clients/active (deprecated)
           The number of currently connected clients.

       $SYS/broker/clients/expired
           The number of disconnected persistent clients that have been expired and removed
           through the persistent_client_expiration option.

       $SYS/broker/clients/disconnected, $SYS/broker/clients/inactive (deprecated)
           The total number of persistent clients (with clean session disabled) that are
           registered at the broker but are currently disconnected.

       $SYS/broker/clients/maximum
           The maximum number of clients that have been connected to the broker at the same time.

       $SYS/broker/clients/total
           The total number of active and inactive clients currently connected and registered on
           the broker.

       $SYS/broker/connection/#
           When bridges are configured to/from the broker, common practice is to provide a status
           topic that indicates the state of the connection. This is provided within
           $SYS/broker/connection/ by default. If the value of the topic is 1 the connection is
           active, if 0 then it is not active. See the Bridges section below for more information
           on bridges.

       $SYS/broker/heap/current size
           The current size of the heap memory in use by mosquitto. Note that this topic may be
           unavailable depending on compile time options.

       $SYS/broker/heap/maximum size
           The largest amount of heap memory used by mosquitto. Note that this topic may be
           unavailable depending on compile time options.

       $SYS/broker/load/connections/+
           The moving average of the number of CONNECT packets received by the broker over
           different time intervals. The final "+" of the hierarchy can be 1min, 5min or 15min.
           The value returned represents the number of connections received in 1 minute, averaged
           over 1, 5 or 15 minutes.

       $SYS/broker/load/bytes/received/+
           The moving average of the number of bytes received by the broker over different time
           intervals. The final "+" of the hierarchy can be 1min, 5min or 15min. The value
           returned represents the number of bytes received in 1 minute, averaged over 1, 5 or 15
           minutes.

       $SYS/broker/load/bytes/sent/+
           The moving average of the number of bytes sent by the broker over different time
           intervals. The final "+" of the hierarchy can be 1min, 5min or 15min. The value
           returned represents the number of bytes sent in 1 minute, averaged over 1, 5 or 15
           minutes.

       $SYS/broker/load/messages/received/+
           The moving average of the number of all types of MQTT messages received by the broker
           over different time intervals. The final "+" of the hierarchy can be 1min, 5min or
           15min. The value returned represents the number of messages received in 1 minute,
           averaged over 1, 5 or 15 minutes.

       $SYS/broker/load/messages/sent/+
           The moving average of the number of all types of MQTT messages sent by the broker over
           different time intervals. The final "+" of the hierarchy can be 1min, 5min or 15min.
           The value returned represents the number of messages send in 1 minute, averaged over
           1, 5 or 15 minutes.

       $SYS/broker/load/publish/dropped/+
           The moving average of the number of publish messages dropped by the broker over
           different time intervals. This shows the rate at which durable clients that are
           disconnected are losing messages. The final "+" of the hierarchy can be 1min, 5min or
           15min. The value returned represents the number of messages dropped in 1 minute,
           averaged over 1, 5 or 15 minutes.

       $SYS/broker/load/publish/received/+
           The moving average of the number of publish messages received by the broker over
           different time intervals. The final "+" of the hierarchy can be 1min, 5min or 15min.
           The value returned represents the number of publish messages received in 1 minute,
           averaged over 1, 5 or 15 minutes.

       $SYS/broker/load/publish/sent/+
           The moving average of the number of publish messages sent by the broker over different
           time intervals. The final "+" of the hierarchy can be 1min, 5min or 15min. The value
           returned represents the number of publish messages sent in 1 minute, averaged over 1,
           5 or 15 minutes.

       $SYS/broker/load/sockets/+
           The moving average of the number of socket connections opened to the broker over
           different time intervals. The final "+" of the hierarchy can be 1min, 5min or 15min.
           The value returned represents the number of socket connections in 1 minute, averaged
           over 1, 5 or 15 minutes.

       $SYS/broker/messages/inflight
           The number of messages with QoS>0 that are awaiting acknowledgments.

       $SYS/broker/messages/received
           The total number of messages of any type received since the broker started.

       $SYS/broker/messages/sent
           The total number of messages of any type sent since the broker started.

       $SYS/broker/messages/stored
           The number of messages currently held in the message store. This includes retained
           messages and messages queued for durable clients.

       $SYS/broker/publish/messages/dropped
           The total number of publish messages that have been dropped due to inflight/queuing
           limits. See the max_inflight_messages and max_queued_messages options in
           mosquitto.conf(5) for more information.

       $SYS/broker/publish/messages/received
           The total number of PUBLISH messages received since the broker started.

       $SYS/broker/publish/messages/sent
           The total number of PUBLISH messages sent since the broker started.

       $SYS/broker/retained messages/count
           The total number of retained messages active on the broker.

       $SYS/broker/subscriptions/count
           The total number of subscriptions active on the broker.

       $SYS/broker/timestamp
           The timestamp at which this particular build of the broker was made. Static.

       $SYS/broker/uptime
           The amount of time in seconds the broker has been online.

       $SYS/broker/version
           The version of the broker. Static.

WILDCARD TOPIC SUBSCRIPTIONS

       In addition to allowing clients to subscribe to specific topics, mosquitto also allows the
       use of two wildcards in subscriptions.  + is the wildcard used to match a single level of
       hierarchy. For example, for a topic of "a/b/c/d", the following example subscriptions will
       match:

       ·   a/b/c/d

       ·   +/b/c/d

       ·   a/+/c/d

       ·   a/+/+/d

       ·   +/+/+/+

       The following subscriptions will not match:

       ·   a/b/c

       ·   b/+/c/d

       ·   +/+/+

       The second wildcard is # and is used to match all subsequent levels of hierarchy. With a
       topic of "a/b/c/d", the following example subscriptions will match:

       ·   a/b/c/d

       ·   #

       ·   a/#

       ·   a/b/#

       ·   a/b/c/#

       ·   +/b/c/#

       The $SYS hierarchy does not match a subscription of "#". If you want to observe the entire
       $SYS hierarchy, subscribe to $SYS/#.

       Note that the wildcards must be only ever used on their own, so a subscription of "a/b+/c"
       is not valid use of a wildcard. The # wildcard must only ever be used as the final
       character of a subscription.

BRIDGES

       Multiple brokers can be connected together with the bridging functionality. This is useful
       where it is desirable to share information between locations, but where not all of the
       information needs to be shared. An example could be where a number of users are running a
       broker to help record power usage and for a number of other reasons. The power usage could
       be shared through bridging all of the user brokers to a common broker, allowing the power
       usage of all users to be collected and compared. The other information would remain local
       to each broker.

       For information on configuring bridges, see mosquitto.conf(5).

SIGNALS

       SIGHUP
           Upon receiving the SIGHUP signal, mosquitto will attempt to reload configuration file
           data, assuming that the -c argument was provided when mosquitto was started. Not all
           configuration parameters can be reloaded without restarting. See mosquitto.conf(5) for
           details.

       SIGUSR1
           Upon receiving the SIGUSR1 signal, mosquitto will write the persistence database to
           disk. This signal is only acted upon if persistence is enabled.

       SIGUSR2
           The SIGUSR2 signal causes mosquitto to print out the current subscription tree, along
           with information about where retained messages exist. This is intended as a testing
           feature only and may be removed at any time.

FILES

       /etc/mosquitto/mosquitto.conf
           Configuration file. See mosquitto.conf(5).

       /var/lib/mosquitto/mosquitto.db
           Persistent message data storage location if persist enabled.

       /etc/hosts.allow, /etc/hosts.deny
           Host access control via tcp-wrappers as described in hosts_access(5).

BUGS

       mosquitto bug information can be found at
       https://bugs.eclipse.org/bugs/describecomponents.cgi?product=Mosquitto

SEE ALSO

       mqtt(7), mosquitto-tls(7), mosquitto.conf(5), hosts_access(5), mosquitto_passwd(1),
       mosquitto_pub(1), mosquitto_sub(1), libmosquitto(3)

THANKS

       Thanks to Andy Stanford-Clark for being one of the people who came up with MQTT in the
       first place. Thanks to Andy and Nicholas O'Leary for providing clarifications of the
       protocol.

       Thanks also to everybody at the Ubuntu UK Podcast and Linux Outlaws for organising
       OggCamp, where Andy gave a talk that inspired mosquitto.

AUTHOR

       Roger Light <roger@atchoo.org>