===== mosquitto =====
==== install ====
  sudo apt-get install mosquitto mosquitto-clients

==== 設定 ====
https://mosquitto.org/man/mosquitto-conf-5.html

/etc/mosquitto/conf.d/mymqtt.conf
  listener  1883
  listener 11883
  protocol websockets 
  #allow_anonymous false
  #password_file /etc/mosquitto/conf.d/passwd.txt

=== passwordファイル ===
/etc/mosquitto/conf.d/passwd.txt
  user:pass

以下のように暗号化する
  mosquitto_passwd -U password.txt


=== logging設定 ===
/etc/mosquitto/conf.d/logging.conf
  log_dest syslog
  log_dest file /var/log/mosquitto/mosquitto.log
  
  #log_type debug
  log_type error
  log_type warning
  log_type notice
  log_type information
  #log_type none
  log_type subscribe
  log_type unsubscribe
  #log_type websockets
  #log_type all
  
  # If set to true, client connection and disconnection messages will be included
  # in the log.
  connection_messages true
  
  # If set to true, add a timestamp value to each log message.
  log_timestamp true