Access denied for user 'root'@'localhost' (using password: NO)

[mariopraga]

This is what i got on my log when I try to start mosquitto .
In my /etc/mosquitto/mosquitto.conf I don't have root user but mqtt user and it's password.

1416657377: mosquitto version 1.3.4 (build date 2014-08-08 09:26:34+0000) starting
1416657377: Config loaded from /etc/mosquitto/mosquitto.conf.
1416657377: |-- *** auth-plug: startup
1416657377: |-- ** Configured order: mysql

1416657377: |-- }}}} MYSQL
Access denied for user 'root'@'localhost' (using password: NO)
1416657377: Opening ipv4 listen socket on port 1883.
1416657377: Opening ipv6 listen socket on port 1883.
1416657378: New connection from xx.xx.xx.xxx on port 1883.

[jpmens]

Without seeing your config it's hard to see what is happening. I'm assuming you configured credentials for MySQL backend incorrectly.

[mariopraga]

This is my mosquitto.conf and start command :
/usr/sbin/mosquitto -d -c /etc/mosquitto/mosquitto.conf > /var/log/mosquitto.log 2>&1 &

pid_file /var/run/mosquitto.pid

persistence true
persistence_location /var/lib/mosquitto/

include_dir /etc/mosquitto/conf.d

auth_plugin /usr/lib64/auth-plug.so
auth_opt_backends mysql

auth_opt_host localhost
auth_opt_port 3306
auth_opt_username mqtt
auth_opt_password mqtt
auth_opt_dbname mqttwarn_db
auth_opt_userquery SELECT pw FROM mosquitto-auth-users WHERE username = '%s'

[mariopraga]

Sorry, I have just found the problem

wrong:
auth_opt_username
auth_opt_password

correct:
auth_opt_user
auth_opt_pass

Still cannot connect with user and password ( have to do some checks ) , instead I noticed a big issue. When i run mosquitto_pub from my linux terminal without using user and password parameters the mosquitto daemon crash.

[jpmens]

You are going to have to give me more information. Linux disto, Mosquitto version, full configs (without your passwords) and exact testing procedures.