Provided by: mosquitto_0.15-0ubuntu1_i386 bug


       mosquitto.conf - the configuration file for mosquitto




       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.


       All  lines  with  a  #  as  the  very  first character are treated as a

       Configuration lines start with a variable name. The variable  value  is
       separated from the name by a single space.


       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

              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.


              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

              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

              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

              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

              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/

              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.


       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.


       The following options are available when external security checks  have
       been  compiled in. Unless you have done this yourself it is unlikely to

       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.




       mosquitto      bug      information      can      be      found      at


       mosquitto(8) mqtt(7) limits.conf(5)


       Roger Light <>

                                5 February 2012              mosquitto.conf(5)