MariaDB debian 9.x

launch: mysql_secure_installation

#MariaDB on debian by default the root user has the plugin unix_socket enabled:

#check auth:
SELECT host,user,password,plugin FROM mysql.user;

#remove (only) unix_socket plugin on mysql internal database
UPDATE mysql.user SET plugin='' WHERE user='root';
FLUSH PRIVILEGES;
quit;

#Create user:
CREATE USER ''username'@'domain'' IDENTIFIED BY 'password_in_chiaro';
FLUSH PRIVILEGES;

#Grant privileges. As root user execute:
GRANT ALL PRIVILEGES ON *.* TO 'root'@'%' IDENTIFIED BY 'password';
GRANT ALL PRIVILEGES ON *.* TO 'root'@'my_ip' IDENTIFIED BY 'root_password' WITH GRANT OPTION;

GRANT ALL PRIVILEGES ON *.* TO 'root'@'%' IDENTIFIED BY 'root_password' WITH GRANT OPTION;
GRANT ALL PRIVILEGES ON *.* TO 'root'@'my_ip' IDENTIFIED BY 'root_password' WITH GRANT OPTION;

SHOW GRANTS FOR 'username'@'domain';

#Create user:
CREATE USER 'username'@'domain' IDENTIFIED BY 'password_in_chiaro';
GRANT ALL ON database.* TO 'username'@'domain';
FLUSH PRIVILEGES;


#delete user;
REVOKE ALL PRIVILEGES, GRANT OPTION FROM 'username'@'domain';
DROP USER DROP USER;

#set tcp access:
/etc/mysql/mariadb.conf.d/50-server.cnf

comment or edit:
#bind-address           = 127.0.0.1  
or 
bind-address = 0.0.0.0


Il campo dominio (dopo @) puo' assumere i valori:
    localhost per indicare che l'utente puo' connettersi solo dalla macchina locale;
    %  per indicare che l'utente puo' connettersi da qualunque IP;
    o altrimenti si puo' indicare la rete o l'IP per indicare che l'utente puo' connettersi da determinati IP;