Provided by: mosquitto_0.15-2+deb7u3ubuntu0.1_amd64 
NAME
mosquitto.conf - the configuration file for mosquitto
SYNOPSIS
mosquitto.conf
DESCRIPTION
mosquitto.conf is the configuration file for mosquitto. This file can reside anywhere as
long as mosquitto can read it. By default, mosquitto does not need a configuration file
and will use the default values listed below. See mosquitto(8) for information on how to
load a configuration file.
FILE FORMAT
All lines with a # as the very first character are treated as a comment.
Configuration lines start with a variable name. The variable value is separated from the
name by a single space.
VARIABLES
acl_file file path
Set the path to an access control list file. If defined, the contents of the file
are used to control client access to topics on the broker.
If this parameter is defined then only the topics listed will have access. Topic
access is added with lines of the format:
topic [read|write] <topic>
The access type is controlled using "read" or "write". This parameter is optional -
if not given then the access is read/write. <topic> can contain the + or #
wildcards as in subscriptions.
The first set of topics are applied to anonymous clients, assuming allow_anonymous
is true. User specific topic ACLs are added after a user line as follows:
user <username>
The username referred to here is the same as in password_file. It is not the
clientid.
It is also possible to define ACLs based on pattern substitution within the topic.
The form is the same as for the topic keyword, but using pattern as the keyword.
pattern [read|write] <topic>
The patterns available for substition are:
• %c to match the client id of the client
• %u to match the username of the client
The substitution pattern must be the only text for that level of hierarchy. Pattern
ACLs apply to all users even if the "user" keyword has previously been given.
Example:
pattern write sensor/%u/data
Reloaded on reload signal. The currently loaded ACLs will be freed and reloaded.
Existing subscriptions will be affected after the reload.
allow_anonymous [ true | false ]
Boolean value that determines whether clients that connect without providing a
username are allowed to connect. If set to false then a password file should be
created (see the password_file option) to control authenticated client access.
Defaults to true.
Reloaded on reload signal.
autosave_interval seconds
The number of seconds that mosquitto will wait between each time it saves the in-
memory database to disk. If set to 0, the in-memory database will only be saved
when mosquitto exits or when receiving the SIGUSR1 signal. Note that this setting
only has an effect if persistence is enabled. Defaults to 1800 seconds (30
minutes).
Reloaded on reload signal.
bind_address address
Listen for incoming network connections on the specified IP address/hostname only.
This is useful to restrict access to certain network interfaces. To restrict access
to mosquitto to the local host only, use "bind_address localhost". This only
applies to the default listener. Use the listener variable to control other
listeners.
Not reloaded on reload signal.
clientid_prefixes prefix
If defined, only clients that have a clientid with a prefix that matches
clientid_prefixes will be allowed to connect to the broker. For example, setting
"secure-" here would mean a client "secure-client" could connect but another with
clientid "mqtt" couldn't. By default, all client ids are valid.
Reloaded on reload signal. Note that currently connected clients will be unaffected
by any changes.
connection_messages < true | false >
If set to true, the log will include entries when clients connect and disconnect.
If set to false, these entries will not appear.
Reloaded on reload signal.
listener port
Listen for incoming network connection on the specified port. A second optional
argument allows the listener to be bound to a specific ip address/hostname. If this
variable is used and neither bind_address nor port are used then the default
listener will not be started. This option may be specified multiple times. See also
the mount_point option.
Not reloaded on reload signal.
log_dest destinations
Send log messages to a particular destination. Possible destinations are: stdout
stderr syslog topic. stdout and stderr log to the console on the named output.
syslog uses the userspace syslog facility which usually ends up in
/var/log/messages or similar and topic logs to the broker topic
'$SYS/broker/log/<severity>', where severity is one of D, E, W, N, I which are
debug, error, warning, notice and information. Use "log_dest none" if you wish to
disable logging. Defaults to stderr. This option may be specified multiple times.
Reloaded on reload signal.
log_timestamp [ true | false ]
Boolean value, if set to true a timestamp value will be added to each log entry.
The default is true.
Reloaded on reload signal.
log_type types
Choose types of messages to log. Possible types are: debug, error, warning, notice,
information, none. Defaults to error, warning, notice and information. This option
may be specified multiple times. Note that the debug type (used for decoding
incoming network packets) is never logged in syslog or topics.
Reloaded on reload signal.
max_connections count
Limit the total number of clients connected for the current listener. Set to -1 to
have "unlimited" connections. Note that other limits may be imposed that are
outside the control of mosquitto. See e.g. limits.conf(5).
Not reloaded on reload signal.
max_inflight_messages count
The maximum number of QoS 1 or 2 messages that can be in the process of being
transmitted simultaneously. This includes messages currently going through
handshakes and messages that are being retried. Defaults to 20. Set to 0 for no
maximum. If set to 1, this will guarantee in-order delivery of messages.
Reloaded on reload signal.
max_queued_messages count
The maximum number of QoS 1 or 2 messages to hold in the queue above those messages
that are currently in flight. Defaults to 100. Set to 0 for no maximum (not
recommended).
Reloaded on reload signal.
mount_point topic prefix
This option is used with the listener option to isolate groups of clients. When a
client connects to a listener which uses this option, the string argument is
attached to the start of all topics for this client. This prefix is removed when
any messages are sent to the client. This means a client connected to a listener
with mount point example can only see messages that are published in the topic
hierarchy example and above.
Not reloaded on reload signal.
password_file file path
Set the path to a password file. If defined, the contents of the file are used to
control client access to the broker. Each line should be in the format
"username:password", where the colon and password are optional but recommended. If
allow_anonymous is set to false, only users defined in this file will be able to
connect. Setting allow_anonymous to true when password_file is defined is valid and
could be used with acl_file to have e.g. read only guest/anonymous accounts and
defined users that can publish.
Reloaded on reload signal. The currently loaded username and password data will be
freed and reloaded. Clients that are already connected will not be affected.
persistence [ true | false ]
Can be true or false. If true, connection, subscription and message data will be
written to the disk in mosquitto.db at the location dictated by
persistence_location. When mosquitto is restarted, it will reload the information
stored in mosquitto.db. The data will be written to disk when mosquitto closes and
also at periodic intervals as defined by autosave_interval. Writing of the
persistence database may also be forced by sending mosquitto the SIGUSR1 signal. If
false, the data will be stored in memory only. Defaults to false.
Reloaded on reload signal.
persistence_file file name
The filename to use for the persistent database. Defaults to mosquitto.db.
Reloaded on reload signal.
persistence_location path
The path where the persistence database should be stored. Must end in a trailing
slash. If not given, then the current directory is used.
Reloaded on reload signal.
pid_file file path
Write a pid file to the file specified. If not given (the default), no pid file
will be written. If the pid file cannot be written, mosquitto will exit. This
option only has an effect is mosquitto is run in daemon mode.
If mosquitto is being automatically started by an init script it will usually be
required to write a pid file. This should then be configured as
/var/run/mosquitto.pid
Not reloaded on reload signal.
port port number
Set the network port for the default listener to listen on. Defaults to 1883.
Not reloaded on reload signal.
retained_persistence [ true | false ]
This is a synonym of the persistence option.
Reloaded on reload signal.
retry_interval seconds
The integer number of seconds after a QoS=1 or QoS=2 message has been sent that
mosquitto will wait before retrying when no response is received. If unset,
defaults to 20 seconds.
Reloaded on reload signal.
store_clean_interval seconds
The integer number of seconds between the internal message store being cleaned of
messages that are no longer referenced. Lower values will result in lower memory
usage but more processor time, higher values will have the opposite effect. Setting
a value of 0 means the unreferenced messages will be disposed of as quickly as
possible. Defaults to 10 seconds.
Reloaded on reload signal.
sys_interval seconds
The integer number of seconds between updates of the $SYS subscription hierarchy,
which provides status information about the broker. If unset, defaults to 10
seconds.
Reloaded on reload signal.
user username
When run as root, change to this user and its primary group on startup. If
mosquitto is unable to change to this user and group, it will exit with an error.
The user specified must have read/write access to the persistence database if it is
to be written. If run as a non-root user, this setting has no effect. Defaults to
mosquitto.
This setting has no effect on Windows and so you should run mosquitto as the user
you wish it to run as.
Not reloaded on reload signal.
CONFIGURING BRIDGES
Multiple bridges (connections to other brokers) can be configured using the following
variables.
Bridges cannot currently be reloaded on reload signal.
address address[:port], addresses address[:port]
Specify the address and optionally the port of the bridge to connect to. This must
be given for each bridge connection. If the port is not specified, the default of
1883 is used.
Unlike rsmb, it is not currently possible to specify multiple addresses for a
single bridge connection here. This is true even if the name "addresses" is used.
cleansession [ true | false ]
Set the clean session option for this bridge. Setting to false (the default), means
that all subscriptions on the remote broker are kept in case of the network
connection dropping. If set to true, all subscriptions and messages on the remote
broker will be cleaned up if the connection drops. Note that setting to true may
cause a large amount of retained messages to be sent each time the bridge
reconnects.
clientid id
Set the client id for this bridge connection. If not defined, this defaults to
'name.hostname', where name is the connection name and hostname is the hostname of
this computer.
connection name
This variable marks the start of a new bridge connection. It is also used to give
the bridge a name which is used as the client id on the remote broker.
keepalive_interval seconds
Set the number of seconds after which the bridge should send a ping if no other
traffic has occurred. Defaults to 60. A minimum value of 5 seconds isallowed.
idle_timeout seconds
Set the amount of time a bridge using the lazy start type must be idle before it
will be stopped. Defaults to 60 seconds.
notifications [ true | false ]
If set to true, publish notification messages to the local and remote brokers
giving information about the state of the bridge connection. Retained messages are
published to the topic $SYS/bridge/connection/<clientid>/state. If the message is
1 then the connection is active, or 0 if the connection has failed. Defaults to
true.
password value
Configure a password for the bridge. This is used for authentication purposes when
connecting to a broker that support MQTT v3.1 and requires a username and/or
password to connect. This option is only valid if a username is also supplied.
start_type [ automatic | lazy | once ]
Set the start type of the bridge. This controls how the bridge starts and can be
one of three types: automatic, lazy and once. Note that RSMB provides a fourth
start type "manual" which isn't currently supported by mosquitto.
"automatic" is the default start type and means that the bridge connection will be
started automatically when the broker starts and also restarted after a short delay
(30 seconds) if the connection fails.
Bridges using the "lazy" start type will be started automatically when the number
of queued messages exceeds the number set with the "threshold" parameter. It will
be stopped automatically after the time set by the "idle_timeout" parameter. Use
this start type if you wish the connection to only be active when it is needed.
A bridge using the "once" start type will be started automatically when the broker
starts but will not be restarted if the connection fails.
threshold count
Set the number of messages that need to be queued for a bridge with lazy start type
to be restarted. Defaults to 10 messages.
topic pattern [ out | in | both ]
Define a topic pattern to be shared between the two brokers. Any topics matching
the pattern (which may include wildcards) are shared. The second parameter defines
the direction that the messages will be shared in, so it is possible to import
messages from a remote broker using "in", export messages to a remote broker using
"out" or share messages in both directions. If this parameter is not defined, the
default of "out" is used.
This option can be specified multiple times per bridge.
Care must be taken to ensure that loops are not created with this option. If you
are experiencing high CPU load from a broker, it is possible that you have a loop
where each broker is forever forwarding each other the same messages.
username name
Configure a username for the bridge. This is used for authentication purposes when
connecting to a broker that support MQTT v3.1 and requires a username and/or
password to connect. See also the password option.
EXTERNAL SECURITY CHECKS
The following options are available when external security checks have been compiled in.
Unless you have done this yourself it is unlikely to exist.
db_host hostname
Database host name.
Reloaded on reload signal.
db_port port
Database port.
Reloaded on reload signal.
db_name name
Database name.
Reloaded on reload signal.
db_username username
Database username.
Reloaded on reload signal.
db_password password
Database password.
Reloaded on reload signal.
FILES
mosquitto.conf
BUGS
mosquitto bug information can be found at http://launchpad.net/mosquitto
SEE ALSO
mosquitto(8) mqtt(7) limits.conf(5)
AUTHOR
Roger Light <roger@atchoo.org>
5 February 2012 mosquitto.conf(5)