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MySQL 8.4 Reference Manual  /  ...  /  NDB Cluster and MySQL Security Procedures NDB Cluster and MySQL Security Procedures

In this section, we discuss MySQL standard security procedures as they apply to running NDB Cluster.

In general, any standard procedure for running MySQL securely also applies to running a MySQL Server as part of an NDB Cluster. First and foremost, you should always run a MySQL Server as the mysql operating system user; this is no different from running MySQL in a standard (non-Cluster) environment. The mysql system account should be uniquely and clearly defined. Fortunately, this is the default behavior for a new MySQL installation. You can verify that the mysqld process is running as the mysql operating system user by using the system command such as the one shown here:

$> ps aux | grep mysql
root     10467  0.0  0.1   3616  1380 pts/3    S    11:53   0:00 \
  /bin/sh ./mysqld_safe --ndbcluster --ndb-connectstring=localhost:1186
mysql    10512  0.2  2.5  58528 26636 pts/3    Sl   11:53   0:00 \
  /usr/local/mysql/libexec/mysqld --basedir=/usr/local/mysql \
  --datadir=/usr/local/mysql/var --user=mysql --ndbcluster \
  --ndb-connectstring=localhost:1186 --pid-file=/usr/local/mysql/var/ \
jon      10579  0.0  0.0   2736   688 pts/0    S+   11:54   0:00 grep mysql

If the mysqld process is running as any other user than mysql, you should immediately shut it down and restart it as the mysql user. If this user does not exist on the system, the mysql user account should be created, and this user should be part of the mysql user group; in this case, you should also make sure that the MySQL data directory on this system (as set using the --datadir option for mysqld) is owned by the mysql user, and that the SQL node's my.cnf file includes user=mysql in the [mysqld] section. Alternatively, you can start the MySQL server process with --user=mysql on the command line, but it is preferable to use the my.cnf option, since you might forget to use the command-line option and so have mysqld running as another user unintentionally. The mysqld_safe startup script forces MySQL to run as the mysql user.


Never run mysqld as the system root user. Doing so means that potentially any file on the system can be read by MySQL, and thus—should MySQL be compromised—by an attacker.

As mentioned in the previous section (see Section, “NDB Cluster and MySQL Privileges”), you should always set a root password for the MySQL Server as soon as you have it running. You should also delete the anonymous user account that is installed by default. You can accomplish these tasks using the following statements:

$> mysql -u root

mysql> UPDATE mysql.user
    ->     SET Password=PASSWORD('secure_password')
    ->     WHERE User='root';

mysql> DELETE FROM mysql.user
    ->     WHERE User='';


Be very careful when executing the DELETE statement not to omit the WHERE clause, or you risk deleting all MySQL users. Be sure to run the FLUSH PRIVILEGES statement as soon as you have modified the mysql.user table, so that the changes take immediate effect. Without FLUSH PRIVILEGES, the changes do not take effect until the next time that the server is restarted.


Many of the NDB Cluster utilities such as ndb_show_tables, ndb_desc, and ndb_select_all also work without authentication and can reveal table names, schemas, and data. By default these are installed on Unix-style systems with the permissions wxr-xr-x (755), which means they can be executed by any user that can access the mysql/bin directory.

See Section 25.5, “NDB Cluster Programs”, for more information about these utilities.